To see the other types of publications on this topic, follow the link: Electrostatic energy.
Dissertations / Theses on the topic 'Electrostatic energy'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Electrostatic energy.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Mur, Miranda José Oscar 1972. "Electrostatic vibration-to-electric energy conversion." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16609.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.<br>Includes bibliographical references (p. 193-197).<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Ultra-Low-Power electronics can perform useful functions with power levels as low as 170 nW. This makes them amenable to powering from ambient sources such as vibration. In this case, they can become autonomous. Motivated by this application, this thesis provides the necessary tools to analyze, design and fabricate MEMS devices capable of electrostatic vibration-to-electric energy conversion at the microwatt level. The fundamental means of en- ergy conversion is a variable capacitor that is excited through a generating energy conversion cycle with every vibration cycle of the converter. This thesis presents a road map on how to design MEMS electrostatic vibration-to- electric energy converters. A proposed converter is designed to illustrate the design process, and is based on vibration levels typical of rotating machinery, which are around 2% of the acceleration of gravity from 1-5 kHz. The converter consists of a square centimeter with a 195 mg proof mass which travels ±200 pm. This mass and travel can couple to a sinusoidal acceleration source of 0.02g at 2.5 kHz, typical of rotating machinery, so as to capture 24 nJ per cycle. This moving proof mass is designed to provide a variable capacitor ranging from 1 pF to 80 pF. Adding a capacitor of 88 pF in parallel with this device will result in a capacitance change from 168 pF to 89 pF that is required to extract 24 nJ using a charge-constrained cycle.<br>(cont.) This device can be attached to power electronics that implement a charge-constrained cycle and deliver 0.5 nJ back to the reservoir for a total power output of 1.3 [mu]/W at 2.5 kHz. The efficiency of the electrical conversion is 2%. Including packaging, the power per volume would be 0.87 [mu]W/cm3 and the power per mass would be 1.3 [mu]W/g. System improvements are also identified such as those that address the principal sources of loss. For example, decreasing the output capacitance of the MOSFET switches from 10 pF to 1 pF, while keeping the energy conversion cycle the same, results in an energy output of 13 nJ out of 24 nJ, for an efficiency of 54% and a power output of 33 [mu]W. This argues strongly for the use of integrated circuits in which the output capacitance of the MOSFET switches can be reduced for this application.<br>José Oscar Mur Miranda.<br>Ph.D.
2
Niu, Feifei. "Dynamic analysis of an electrostatic energy harvesting system." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82843.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 97-99).<br>Traditional small-scale vibration energy harvesters have typically low efficiency of energy harvesting from low frequency vibrations. Several recent studies have indicated that introduction of nonlinearity can significantly improve the efficiency of such systems. Motivated by these observations we have studied the nonlinear electrostatic energy harvester using a combination of analytical and numerical approaches. The analytical approach was based on the normal vibration mode analysis around an equilibrium point. The numerical model was implemented and tested using Modelica language. It was found that the efficiency of energy transfer strongly depends on three parameters: the ratio between the maximal electrical and mechanical energies in the system and ratio of natural frequencies of electric and mechanical modes, and finally the dimensionless degree of nonlinearity in the system. The dependence of the transfer factor on these three parameters was studied and characterized both theoretically and numerically. It was found that the transfer factor Tr has a sharply pronounced peak as a function of e providing a possibility of efficient energy conversion between modes with highly different normal frequencies.<br>by Feifei Niu.<br>S.M.
3
Aljadiri, R. T. "Modelling and design of electrostatic based wind energy harvester." Thesis, Coventry University, 2014. http://curve.coventry.ac.uk/open/items/9ee6a6e1-bd1d-4717-b48d-ee48fefb4657/1.
Full textAbstract:
Wireless sensor networks and portable electronic devices, such as mobile phones, media players, digital cameras and iPods, require local electric power supplies. Although these devices are operational all the time, they consume just a few milli-or micro-watts. This means energy harvesting from the environment is an attractive option for powering these devices. Mechanical energy harvesters can use electromagnet, electrostatic or piezoelectric approaches. Of these, electrostatic devices are found to be the most suitable approach for harvesting mechanical energy since they are compact, sensitive to low level mechanical energy, easier to integrate in small scale systems, not requiring smart materials, simple to fabricate, inexpensive and simply structured using less circuitry. Most of electrostatic harvesters proposed in previous studies use mechanical vibration. However, only a few studies have investigated harvesting rotational mechanical energy. The objective of this thesis is to investigate the possibility of harvesting rotational mechanical energy from wind using the electrostatic approach. The proposal involves capturing wind energy using a micro wind turbine then converting it into usable electrical energy. This work first considers general design considerations and the design procedure that must be followed to construct a suitable electrostatic based wind energy harvester. Second, it describes the operating principles of various parts needed to design a novel efficient electrostatic harvesting system. The new harvester consists of a micro wind turbine, a gearbox, a multi-pole variable capacitor or capacitor array, an LC to LC energy transfer circuit, a capacitance sensing system and a microcontroller. The harvesting process has three main steps. First, wind energy is captured and converted into mechanical power using the micro wind turbine. Second, mechanical power is converted into electrical power using the variable capacitor in three phases: pre-charge, harvest and reset. Third, the electrical energy is processed and stored in a Lithium ion battery. The proposed harvester was simulated using Matlab/Simulink to study energy transfer throughout the three energy harvesting phases. Energy analysis was then carried out to study the effect of varying the structure of the multi-pole capacitor on the amount of harvested energy. Results from the simulation for capacitance variation from 2.5 nF to 0.6 nF indicated that an eight-pole variable capacitor can produce 29.43 μJ/sec at a wind speed of 10 m/sec, while a capacitor array of the same capacitance variation with 10 capacitors in the array can produce 295 μJ/sec at a wind speed of 10 m/sec. The results of experiments were carried out to test wind harvesting using a two-pole capacitor proved that the proposed harvester is capable of powering an RF transmitter to transmit wind speed information wirelessly.
4
Karami, Armine. "Study of electrical interfaces for electrostatic vibration energy harvesting." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS134/document.
Full textAbstract:
Les récupérateurs d'énergie vibratoire électrostatiques (REV) sont des systèmes convertissant une partie de l'énergie cinétique de leur environnement en énergie électrique, afin d'alimenter de petits systèmes électroniques. Les REV inertiels sont constituées d'un sous-système mécanique bâti autour d'une masse mobile, ainsi que d'une interface électrique. Ces deux blocs sont couplés par un transducteur électrostatique. Cette thèse étudie l'amélioration des performances des REV par la conception optimisée de leur interface électrique. La première partie de cette thèse étudie une famille d'interfaces électriques appelées pompes de charge (PC). On commence par la construction d'une théorie formelle des PC. Des interfaces rapportées dans la littérature sont identifiées comme membres de cette famille. Cette dernière est ensuite complétée par une nouvelle topologie de PC. Une comparaison des différents PC est alors faite dans le domaine électrique, puis un outil semi-analytique est présenté pour la comparaison des PC en prenant en compte le couplage électromécanique. L'étude des PC se termine par la présentation d'une nouvelle méthode de mesure du potentiel d'électret des REV. La deuxième partie de la thèse présente une approche de conception radicalement différente de ce qui est présenté dans les travaux actuels sur les REV. Elle préconise une synthèse active de la dynamique de la masse des REV à travers leur interface électrique. Nous montrons d'abord que cela permet la conversion d'énergie en quantités proches des limites physiques, et ce à partir de vibrations d'entrée de forme arbitraire. Enfin, une architecture pour un tel REV est proposée et testée en simulation<br>Electrostatic vibration energy harvesters (e-VEHs) are systems that convert part of their surroundings' kinetic energy into electrical energy, in order to supply small-scale electronic systems. Inertial E-VEHs are comprised of a mechanical subsystem that revolves around a mobile mass, and of an electrical interface. The mechanical and electrical parts are coupled by an electrostatic transducer. This thesis is focused on improving the performances of e-VEHs by the design of their electrical interface. The first part of this thesis consists in the study of a family of electrical interfaces called charge-pumps conditioning circuits (CPCC). It starts by building a formal theory of CPCCs. State-of-the-art reported conditioning circuits are shown to belong to this family. This family is then completed by a new CPCC topology. An electrical domain comparison of different CPCCs is then reported. Next, a semi-analytical tool allowing for the comparison of CPCC-based e-VEHs accounting for electromechanical effects is reported. The first part of the thesis ends by presenting a novel method for the measurement of e-VEHs' built-in electret potential. The second part of the thesis presents a radically different design approach than what is followed in most of state-of-the-art works on e-VEHs. It advocates for e-VEHs that actively synthesize the dynamics of their mobile mass through their electrical interface. We first show that this enables to convert energy in amounts approaching the physical limits, and from arbitrary types of input vibrations. Then, a complete architecture such an e-VEH is proposed and tested in simulations submitted to human body vibrations
5
Karami, Armine. "Study of electrical interfaces for electrostatic vibration energy harvesting." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS134.pdf.
Full textAbstract:
Les récupérateurs d'énergie vibratoire électrostatiques (REV) sont des systèmes convertissant une partie de l'énergie cinétique de leur environnement en énergie électrique, afin d'alimenter de petits systèmes électroniques. Les REV inertiels sont constituées d'un sous-système mécanique bâti autour d'une masse mobile, ainsi que d'une interface électrique. Ces deux blocs sont couplés par un transducteur électrostatique. Cette thèse étudie l'amélioration des performances des REV par la conception optimisée de leur interface électrique. La première partie de cette thèse étudie une famille d'interfaces électriques appelées pompes de charge (PC). On commence par la construction d'une théorie formelle des PC. Des interfaces rapportées dans la littérature sont identifiées comme membres de cette famille. Cette dernière est ensuite complétée par une nouvelle topologie de PC. Une comparaison des différents PC est alors faite dans le domaine électrique, puis un outil semi-analytique est présenté pour la comparaison des PC en prenant en compte le couplage électromécanique. L'étude des PC se termine par la présentation d'une nouvelle méthode de mesure du potentiel d'électret des REV. La deuxième partie de la thèse présente une approche de conception radicalement différente de ce qui est présenté dans les travaux actuels sur les REV. Elle préconise une synthèse active de la dynamique de la masse des REV à travers leur interface électrique. Nous montrons d'abord que cela permet la conversion d'énergie en quantités proches des limites physiques, et ce à partir de vibrations d'entrée de forme arbitraire. Enfin, une architecture pour un tel REV est proposée et testée en simulation<br>Electrostatic vibration energy harvesters (e-VEHs) are systems that convert part of their surroundings' kinetic energy into electrical energy, in order to supply small-scale electronic systems. Inertial E-VEHs are comprised of a mechanical subsystem that revolves around a mobile mass, and of an electrical interface. The mechanical and electrical parts are coupled by an electrostatic transducer. This thesis is focused on improving the performances of e-VEHs by the design of their electrical interface. The first part of this thesis consists in the study of a family of electrical interfaces called charge-pumps conditioning circuits (CPCC). It starts by building a formal theory of CPCCs. State-of-the-art reported conditioning circuits are shown to belong to this family. This family is then completed by a new CPCC topology. An electrical domain comparison of different CPCCs is then reported. Next, a semi-analytical tool allowing for the comparison of CPCC-based e-VEHs accounting for electromechanical effects is reported. The first part of the thesis ends by presenting a novel method for the measurement of e-VEHs' built-in electret potential. The second part of the thesis presents a radically different design approach than what is followed in most of state-of-the-art works on e-VEHs. It advocates for e-VEHs that actively synthesize the dynamics of their mobile mass through their electrical interface. We first show that this enables to convert energy in amounts approaching the physical limits, and from arbitrary types of input vibrations. Then, a complete architecture such an e-VEH is proposed and tested in simulations submitted to human body vibrations
6
CHáVEZ, YZQUIERDO Jhordan. "Semi-passive conditionning circuits for efficient electrostatic energy harvesting." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST185.
Full textAbstract:
La thèse explore la récupération d'énergie à petite échelle, en se concentrant sur les circuits de récupération d'énergie électrostatique. Elle vise à convertir l'énergie ambiante en électricité pour alimenter de manière durable des dispositifs électroniques et des capteurs, notamment dans des endroits éloignés ou inaccessibles.Cette technologie pourrait remplacer les batteries traditionnelles, qui souffrent de fuites, de capacité limitée et de sensibilité aux fluctuations de température. Elle prolonge la durée de vie des dispositifs et réduit la nécessité de recharges fréquentes, ce qui est crucial pour l'Internet des Objets (IoT). Les technologies de récupération d'énergie soutiennent l'autonomie et la flexibilité des déploiements IoT, réduisant les coûts de maintenance et permettant une surveillance en temps réel et une maintenance prédictive.La thèse analyse l'état de l'art des circuits de récupération d'énergie électrostatique, en se concentrant sur leur efficacité et leur mise en œuvre pratique à travers des diagrammes QV. Les circuits à cycle QV rectangulaire, bien que simples, sont moins efficaces, tandis que les circuits à cycle QV triangulaire offrent de meilleures performances mais sont plus complexes à mettre en œuvre.Une approche innovante combine les avantages des deux types de circuits, proposant une technique semi-passive où la charge et la décharge du transducteur sont synchronisées avec le mouvement structurel, utilisant des commutateurs contrôlables pour maintenir des cycles triangulaires. Cet équilibre entre simplicité et efficacité est une contribution clé de cette recherche.La thèse explore également différents types de transducteurs pour la récupération d'énergie électrostatique. Les transducteurs MEMS offrent une haute précision et une miniaturisation, mais rencontrent des problèmes d'efficacité à haute fréquence. Les condensateurs à base de polymères atteignent une haute capacitance mais ont des pertes d'énergie importantes dans le transducteur lui-même. Les condensateurs battants convertissent efficacement l'énergie vibratoire mais nécessitent une conception mécanique précise. Les Condensateurs Métalliques Accordables, utilisés dans des circuits résonants, sont simples à mettre en œuvre et ont des pertes d'énergie modérées (dans le transducteur lui-même), ce qui en fait une option fiable pour les circuits développés. Ainsi, le Condensateur Métallique Accordable est choisi pour valider les circuits développés.Un aspect particulier de la thèse est l'exploration de l'élément photocapacitif, utilisant des matériaux sensibles à la lumière pour convertir l'énergie lumineuse en électricité. Initialement conçu comme un condensateur variable, les expériences ont montré que cet élément fonctionne principalement comme un générateur de courant lorsqu'il est exposé à la lumière. Des tests avec le circuit doubleur de Bennet ont révélé que le transducteur génère du courant sans tension de polarisation appliquée, suggérant un mode de fonctionnement différent qui pourrait être exploré davantage.La recherche introduit la méthode SCDI (Charge et Décharge Synchronisées sur Inductance), équilibrant simplicité et efficacité dans la conversion d'énergie. Cette méthode synchronise les cycles de charge et de décharge à travers une inductance, améliorant la conversion des vibrations mécaniques en énergie électrique. Les tests ont montré que la méthode SCDI pouvait convertir environ 1 µJ d'énergie par cycle (avec un composant de stockage de 60V), nécessitant des transducteurs à faibles pertes pour un transfert d'énergie efficace.S'appuyant sur la méthode SCDI, la thèse présente la technique SCDIP (Charge et Décharge Synchronisées sur Inductance avec Cycle Positif), utilisant uniquement un cycle QV positif pour améliorer encore l'efficacité. Cette méthode réduit les pertes d'énergie dans le transducteur, améliorant significativement les performances de récupération d'énergie par rapport à la méthode SCDI<br>The thesis explores small-scale energy harvesting, focusing on electrostatic energy harvesting circuits. It aims to convert ambient energy into electricity to sustainably power electronic devices and sensors, especially in remote or inaccessible locations.This technology could replace traditional batteries, which suffer from leaks, limited capacity, and sensitivity to temperature fluctuations. It extends the lifespan of devices and reduces the need for frequent recharges, which is crucial for the Internet of Things (IoT). Energy harvesting technologies support the autonomy and flexibility of IoT deployments, reducing maintenance costs and enabling real-time monitoring and predictive maintenance.The thesis analyzes the state of the art in electrostatic energy harvesting circuits, focusing on their efficiency and practical implementation through QV (charge-voltage) diagrams. Rectangular QV cycle circuits, although simple, are less efficient, while triangular QV cycle circuits offer better performance but are more complex to implement.An innovative approach combines the advantages of both types of circuits, proposing a semi-passive technique where the transducer's charge and discharge are synchronized with structural movement, using controllable switches to maintain triangular cycles. This balance between simplicity and efficiency is a key contribution of this research.The thesis also explores various types of transducers for electrostatic energy harvesting. MEMS transducers offer high precision and miniaturization but they face efficiency issues at high frequencies. Polymer-based capacitors achieve high capacitance but they have lot of energy loss on the transducer itself. Flapping capacitors efficiently convert vibrational energy but require precise mechanical design. Adjustable Metal Capacitors, used in resonant circuits, are simple to implement and they have moderate energy loss (on the transducer itself), making them a reliable option for the developed circuits. Thus, the Adjustable Metal Capacitor is chosen to validate the developed circuits.A particular aspect of the thesis is the exploration of the photocapacitive element, using light-sensitive materials to convert light energy into electricity. Initially designed as a variable capacitor, experiments showed that this element functions primarily as a current generator when exposed to light. Tests with the Bennet doubler circuit revealed that the transducer generates current without an applied bias voltage, suggesting a different operating mode that could be further explored.The research introduces the SCDI method (Synchronized Charge and Discharge on Inductance), balancing simplicity and efficiency in energy conversion. This method synchronizes charge and discharge cycles through an inductance, improving the conversion of mechanical vibrations into electrical energy. Tests showed that the SCDI method could convert about 1 µJ of energy per cycle (with a 60V storage component), requiring low-loss transducers for efficient energy transfer.Building on the SCDI method, the thesis presents the SCDIP technique (Synchronized Charge and Discharge on Inductance with Positive Cycle), using only a positive QV cycle to further improve efficiency. This method reduces energy losses in the transducer, significantly enhancing energy harvesting performance compared to the SCDI method
7
Su, Yi-chuan. "Theoretical and experimental characterisation of energy in an electrostatic discharge." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63476/1/Yi-chuan_Su_Thesis.pdf.
Full textAbstract:
Electrostatic discharges have been identified as the most likely cause in a number of incidents of fire and explosion with unexplained ignitions. The lack of data and suitable models for this ignition mechanism creates a void in the analysis to quantify the importance of static electricity as a credible ignition mechanism. Quantifiable hazard analysis of the risk of ignition by static discharge cannot, therefore, be entirely carried out with our current understanding of this phenomenon.
The study of electrostatics has been ongoing for a long time. However, it was not until the wide spread use of electronics that research was developed for the protection of electronics from electrostatic discharges. Current experimental models for electrostatic discharge developed for intrinsic safety with electronics are inadequate for ignition analysis and typically are not supported by theoretical analysis.
A preliminary simulation and experiment with low voltage was designed to investigate the characteristics of energy dissipation and provided a basis for a high voltage investigation. It was seen that for a low voltage the discharge energy represents about 10% of the initial capacitive energy available and that the energy dissipation was within 10 ns of the initial discharge. The potential difference is greatest at the initial break down when the largest amount of the energy is dissipated. The discharge pathway is then established and minimal energy is dissipated as energy dissipation becomes greatly influenced by other components and stray resistance in the discharge circuit. From the initial low voltage simulation work, the importance of the energy dissipation and the characteristic of the discharge were determined.
After the preliminary low voltage work was completed, a high voltage discharge experiment was designed and fabricated. Voltage and current measurement were recorded on the discharge circuit allowing the discharge characteristic to be recorded and energy dissipation in the discharge circuit calculated. Discharge energy calculations show consistency with the low voltage work relating to discharge energy with about 30-40% of the total initial capacitive energy being discharged in the resulting high voltage arc.
After the system was characterised and operation validated, high voltage ignition energy measurements were conducted on a solution of n-Pentane evaporating in a 250 cm3 chamber.
A series of ignition experiments were conducted to determine the minimum ignition energy of n-Pentane. The data from the ignition work was analysed with standard statistical regression methods for tests that return binary (yes/no) data and found to be in agreement with recent publications.
The research demonstrates that energy dissipation is heavily dependent on the circuit configuration and most especially by the discharge circuit's capacitance and resistance. The analysis established a discharge profile for the discharges studied and validates the application of this methodology for further research into different materials and atmospheres; by systematically looking at discharge profiles of test materials with various parameters (e.g., capacitance, inductance, and resistance). Systematic experiments looking at the discharge characteristics of the spark will also help understand the way energy is dissipated in an electrostatic discharge enabling a better understanding of the ignition characteristics of materials in terms of energy and the dissipation of that energy in an electrostatic discharge.
8
McLellan, P. G. "Control of rectifier equipment used for electrostatic precipitation." Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375938.
Full text
9
Sakalli, Ilkay [Verfasser]. "Robust Finite Element Solver for Molecular Electrostatic Energy Computations / Ilkay Sakalli." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1074139518/34.
Full text
10
Kundrapu, Madhusudhan, Michael Keidar, and Charles Jones. "Electrostatic Approach for Mitigation of Communication Attenuation During Directed Energy Testing." International Foundation for Telemetering, 2009. http://hdl.handle.net/10150/606128.
Full textAbstract:
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada<br>Electrostatic approach is considered for mitigation of communication attenuation during the testing of laser powered directed energy weapon. Mitigation analysis is carried out for two target materials Al and Ti. Plasma parameters are obtained using one dimensional coupled analysis of laser-target interaction. Influence of laser beam frequency on plasma parameters is addressed. Sheath thickness is obtained using transient sheath calculations. It is found that uninterrupted telemetry can be achieved | using a maximum bias voltage of 10 kV, through Al plasma for fluences below 5 J/cm² and through Ti plasma for fluences below 2 J/cm².
11
Lee, Lee-Peng 1969. "Optimization of electrostatic binding free energy : application to barnase and barstar." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85331.
Full text
12
Holguín, Weber Eduardo Javier. "IP for electrostatic MEMS-based integrated energy harvester in GaN-on-Sitechnology." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS672.
Full textAbstract:
Cette étude porte sur le développement complet d'un système de récupération d'énergie utilisant un transducteur capacitif MEMS. L'accent est mis sur l'intégration de systèmes autonomes pour alimenter ces dispositifs grâce aux récupérateurs MEMS. La recherche explore le potentiel de la technologie GaN pour la récupération d'énergie, optimise les techniques de fabrication et évalue les performances des dispositifs.Une analyse détaillée du dispositif MEMS spécialement conçu pour la récupération d'énergie est présentée. Ce dispositif, le résonateur à peigne avec ressorts linéaires, offre une large bande passante de fonctionnement couvrant le spectre des basses fréquences (10-100 Hz), permettant la récupération d'énergie à faibles amplitudes d'excitation.La fabrication des MEMS se fait en salle blanche sur des plaquettes SOG, réduisant la capacité parasite et augmentant la capacité motrice. Un modèle analytique explique le comportement des MEMS. Les performances sont évaluées à travers des simulations et des analyses, offrant une vision complète du modèle computationnel.La recherche se penche sur la conception d'un récupérateur d'énergie vibratoire, en se concentrant sur le système de pompe de charge basé sur un dispositif MEMS capacitif. La capacité du circuit à convertir les variations de capacité dynamique en énergie électrique est soulignée, tout comme la relation entre la résistance de charge et les performances du système. L'intégration de la technologie GaN est explorée pour améliorer l'efficacité énergétique.L'étude présente une approche complète de la conception d'une unité de gestion de l'alimentation (PMU) pour les systèmes MEMS de récupération d'énergie par vibration. Cette PMU comprend une unité d'isolation et un comparateur à ultra-basse puissance, utilisant des technologies silicium et GaN. Le comparateur garantit une tension de sortie constante, adaptée aux besoins des circuits en aval, pour les deux paradigmes technologiques (silicium et GaN) présentant leurs avantages respectifs<br>This study involves a comprehensive research and design of an energy harvesting system using a electrostatic transducer based on microelectromechanical system (MEMS). The research focuses on integrating autonomous systems, with an emphasis on developing efficient techniques to power them using MEMS energy harvesters. The research extensively investigates the potential of GaN and Silicon technologies for energy harvesting, including a detailed analysis of its material properties, optimization of fabrication techniques, and characterization of device performance. In addition, the study undertakes an evaluation of various wafer substrates, with a special focus on their microscaling capabilities, while emphasizing the critical importance of wafer selection.This study presents a detailed analysis of the selection, characterization, and behavior of a special MEMS device designed for energy harvesting. This selected MEMS device, termed a comb drive resonator with linear springs that closes the gap, exhibits exceptional characteristics. Significantly, it has a wide operating bandwidth that spans the low-frequency spectrum from 10-100 Hz, allowing electrical energy to be harvested even at excitation amplitudes below 1g.The fabrication of MEMS is typically performed in a clean-room environment using silicon-on-glass (SOG) wafers as the base. This approach offers the advantage of reducing parasitic capacitance and increasing motional capacitance due to the thick layers of material. Additionally, in this work, we utilize an analytical model to explain the behavior of MEMS, including the assumptions, parameters, and techniques used, without directly fabricating them.The performance evaluation of the study uncovers innovative opportunities for autonomous systems, thereby establishing a fundamental platform for the design and optimization of vibration-based energy harvesting devices. The investigation includes extensive simulation and response analysis of the system, providing a holistic representation of the computational model. Specifically, the study describes the design of a charge pump and the careful selection of system components, incorporating both discrete methods and the use of commercially available components.Particular focus of the research focuses on the electronic design of a vibrational energy harvester, particularly the charge pump system based on an electrostatic MEMS device. The circuit's capability to convert the transducer's dynamic capacitance changes into electrical energy makes it suitable for low-power energy harvesting applications. Furthermore, the relationship between load resistance and system performance is thoroughly examined. These findings demonstrate the advantages of incorporating gallium nitride (GaN) technology and optimizing component integration to improve energy efficiency and system performance.This paper presents a comprehensive approach to the design and implementation of a power management unit (PMU) tailored for vibrational energy harvesting MEMS systems. This PMU consists of two key components: an isolation unit and an ultra-low-power comparator. It is implemented using two different technologies: a 180nm silicon PDK and a GaN PDK in SOI for high-voltage applications. The voltage comparator, the foundation of the system, guarantees a constant DC output voltage between 2 and 5 volts for silicon and 1.9V to 2.4 volts for GaN. It also controls the charging and discharging cycles of the system, which fulfills the needs of the downstream circuits. This operating profile makes it suitable for applications that require specific operating parameters. Through a sophisticated analysis, optimal performance is achieved for two different technology paradigms: silicon-based and GaN-based harvester systems, each with its own set of advantages and limitations
13
Chen, Yizhou. "Adhesion of Spider Glue on Different Surface Energy and Surface Potential Surfaces." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1462227997.
Full text
14
Torres, Erick Omar. "An electrostatic CMOS/BiCMOS Li ion vibration-based harvester-charger IC." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34823.
Full textAbstract:
The primary objective of this research was to investigate and develop an electrostatic energy-harvesting voltage-constrained CMOS/BiCMOS integrated circuit (IC) that harnesses ambient kinetic energy from vibrations with a vibration-sensitive variable capacitor and channels the extracted energy to charge an energy-storage device (e.g., battery). The proposed harvester charges and holds the voltage across the vibration-sensitive variable capacitor so that vibrations can induce it to generate current into the battery when capacitance decreases (as its plates separate). To that end, the research developed an energy-harvesting system that synchronizes to variable capacitor's state as it cycles between maximum and minimum capacitance by controlling each functional phase of the harvester and adjusting to different voltages of the on-board battery. One of the major challenges of the system was performing all of these duties without dissipating the energy harnessed and gained from the environment. Consequently, the system reduces losses by time-managing and biasing its circuits to operate only when needed and with just enough energy while charging the capacitor through an efficient inductor-based precharger. As result, the proposed energy harvester stores a net energy gain in the battery during each vibration cycle.
15
Gorur, Murat. "ECC-D4 Electostatic Oil Cleaner Design for Heavy-Duty Gas Turbine Applications." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-58523.
Full textAbstract:
The turbine technology improvements from 1980 onwards have considerably increased mechanical and thermal stresses on turbine oils which, cause oil oxidation and thereby turbine oil degradation (Livingstone et al., 2007; Sasaki & Uchiyama, 2002). If the oil degradation problem is ignored, this might result in serious turbine system erratic trips and start-up operational problems (Overgaag et al., 2009). Oil oxidation by-products, in other words, sludge and varnish contaminants, lead stated turbine operation-tribological problems. Hence, sludge and varnish presence in turbine oil become a major reason for declining turbine reliability and availability. In the power generation industry, heavy-duty gas turbines as well as steam turbines have been lubricated with mineral based turbine oils for many decades (Okazaki & Badal, 2005). First, generally Group I oils (mineral base oils produced by solvent extraction, dewaxing) were used. Nevertheless, this group of oils has lower oxidation resistance. Therefore, modern gas turbines demand oils which have better oil oxidation resistance, and lower sludge and varnish contaminants tendency (Hannon, 2009). Today, there are many turbine lubricants available on the market. Besides Group I oils, more and more Group II oils (mineral base oils produced by hydro cracking and hydro treating) are selected in service, and having increased oil oxidation resistance. However field inspections demonstrate that Group II oils also experience sludge and varnish problems as well as Group I oils. Primary reason for these phenomena is the antioxidant additive packages that are used in Group II oils (Overgaag et al., 2009). In any case with recent oil formulations, oil degradation products still exist in current turbine oils, and will continue to do so in natural process. These sludge and varnish contaminants are less than 1 micron in size. Thus, they can pass turbine oil system standard mechanical filters without obstruction. With regard to keep the turbine systems in best operational conditions, external turbine oil cleaning practices became crucial to remove these less than 1 micron size oil degradation products from turbine oils. Current effective method for removing the sludge and varnish is to use electrostatic oil cleaners (Moehle & Gatto et al., 2007). Since the majority of turbine user and operator population have been shifted to use Group II based oils to counter the increased sludge and varnish problems, traditional oil cleaners became insufficient to remove sludge and varnish from Group II. (Due to Group II oils have different oil characteristics such as oil oxidation stability and solvency capability). With this awareness, thesis project is looking for ways to introduce and develop an Advanced Electrostatic Oil Cleaner to increase the availability and reliability figures of heavy-duty gas turbines against the rising amount of oil degradation products in modern formulated turbine oils. ECC (Electrostatic Cooled Cleaner) is an electrostatic oil cleaner device to clean and cool mineral based turbine oils for heavy-duty gas turbine applications by removing the sludge and varnish - oil contaminants from turbine oils. The basic principle of the ECC is based on the electrostatic force produced by parallel positioned electrodes which are charged with a high D.C. voltage. Oil contaminants- sludge and varnish have polar nature. Therefore, they are attracted by electrostatic forces whose intensity is proportional to the voltage applied. With the oil flowing in parallel to these electrodes, the polar particles in the oil (which is only neutral /no polar) are caught by filter media positioned between these electrodes. Small investments on advanced oil cleaner result in big savings on turbine system performance. Increased turbine availability and reliability predominantly reduce maintenance costs and risks besides, and thus maximizing revenue by extending heavy-duty gas turbine operational life. An introduced prototype of the ECC-D4 model was tested using two Group II and one Group I oils. The amounts of 200 liter (each) test oils were circulated approximately 300 times through the ECC-D4. In each 3 oil cleaning test sessions, it is proved that the oil insolubles content decreased approximately 40% in tested turbine oils within about 240 ECC-D4 operating hours. With taken base of heavy-duty gas turbine characteristics such as 400 MW power production capacity, annually 8000 operating hours, and 15000 liter oil reservoir volume; it is estimated that the ECC-D4 can extend the oil service-life from 24000 to 48000 operating hours (which is approximately the oil service end-life). In addition to that, assuming the ECC-D4 investment cost as 30k€, about 15k€ savings per year through the new turbine oil and component replacement costs, besides turbine operation profit losses. Moreover, the ECC-D4 returns on investment with a rate of 39 % for defined heavy-duty gas turbine. In general perspective of ECC-D4, it makes heavy-duty gas turbine infrastructure innovative, fully integrated and committed to fulfilling the need for clean, efficient, reliable power production practices in an environmental manner.
16
Mahmood, Paracha Ayyaz. "Design and fabrication of Mems-based, vibration powered energy harvesting device using electrostatic transduction." Phd thesis, Université Paris-Est, 2009. http://tel.archives-ouvertes.fr/tel-00584339.
Full textAbstract:
Due to size effects, the microtechnologies that are used to manufacture micro-sensors, allowed a drastic reduction of electrical power consumption. This feature contributed to the emergence of the concept of autonomous sensors, which have the ability to take the energy needed for their operation from the environment where they are located. Among the different energy sources, our choice was made on ambient mechanical vibrations. The electromechanical conversion is done within a transducer integrated with a micromechanical structure. In this work, we have designed and fabricated an electrostatic transducer based on silicon-glass technology, which required the development of a dedicated deep etching process. The device was tested experimentally and we have obtained a conversion of mechanical energy into electrical energy, corresponding to a power of 61 nW, with a device whose surface area is only 66 mm². This device is the first miniaturized silicon converter based on electrostatic transduction which does not use an electret
17
Kieseritzky, Gernot [Verfasser]. "Shaping electrostatic energy computations in proteins : the ClC‐type proton‐chloride antiporter function / Gernot Kieseritzky." Berlin : Freie Universität Berlin, 2011. http://d-nb.info/1025354222/34.
Full text
18
Aono, Shinji. "Theoretical Study of Electrostatic Solvent Effects within Free Energy Expression and Application to Solvated Reaction." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/126827.
Full text
19
Ji, Ming Chao. "Molecular relaxation dynamics of Anthracene cations studied in an electrostatic storage ring." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10051.
Full textAbstract:
Les molécules hydrocarbures aromatiques polycycliques (HAP) sont à l'heure actuelle considérées comme probablement responsables des bandes d'émission infrarouge non identifiées du milieu interstellaire (MIS). La dynamique de refroidissement des molécules HAP est essentielle pour estimer leur photo-stabilité, leur durée de vie et les distributions de taille dans le MIS. Au cours des dernières années, les expériences s'appuyant sur le stockage électrostatique d'ions moléculaires ou d'agrégats sont devenus des outils puissants pour étudier leur refroidissement dans une large gamme de temps allant de la microseconde à quelques secondes. En général, l'étude des courbes de déclin associées aux processus de dissociation dans le cas des cations ou bien de détachement d'électrons dans le cas des anions fournit des informations sur l'évolution de l'énergie interne des ions stockés. Dans ce travail de thèse, le refroidissement de cations d'anthracène a été étudié dans un anneau de stockage électrostatique compact, le Mini-Ring, jusqu'à 8 ms. Les courbes de déclin spontané provenant de la dissociation par émission de fragment C2H2 ou H neutres montrent trois régions distinctives. Ces trois régions indiquent différents régimes de refroidissement en fonction du temps de stockage, la dissociation domine pour les temps inférieurs à 1 ms, l'effet de l'émission radiative entre alors en compétition avec la dissociation puis domine au-delà de 3 ms<br>The polycyclic aromatic hydrocarbon (PAH) molecules have been considered as possible carrier of the unidentified infrared emission bands from the interstellar medium (ISM) for about thirty years. The cooling dynamics of the PAH molecules which is essential to estimate their photostability and therefore their lifetime and size distributions in the ISM, has attracted numerous theoretical and experimental studies. In recent years, electrostatic storage devices (ESD) became powerful tool to investigate the cooling regime of molecules and clusters in a large time range from microseconds to seconds. Generally speaking, the decay of the emitted neutral yields due to dissociation of molecular cations or electron detachment of anions in such experiments carries information on the internal energy of the stored molecular ions. In this thesis work, the cooling regimes of anthracene cations are studied by following the time evolution of the internal energy distribution (IED) of the stored anthracene cations. A spontaneous neutral yield curve obtained from the stored molecular ions as a function of the storage time shows three distinguishable regions. The three regions indicate different cooling regimes at corresponding storage time range, i.e., the dissociation mechanism of the molecule dominates at storage time t < 1 ms, quenching of the dissociation by radiative cooling processes occurs during 1 < t < 3 ms and radiative cooling governs at t > 3 ms
20
Godbout, Lynda. "Atomic force microscopy studies on the electrostatic environment and energy levels of self-assembled quantum dots." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96933.
Full textAbstract:
The ability of quantum dots to confine single charges at discrete energy levels makes them a promising platform for novel electronic and optoelectronic devices. Self-assembled quantum dots are of considerable interest because their size, shape, and material can be controlled during growth. These properties influence the confinement potential, thereby controlling the energy levels of the dot. However, the method of growth does not allow for positioning of the quantum dots which end up randomly distributed over the sample surface, making it difficult for lithographic techniques to access the quantum dots to perform either charge transport or charge sensing measurements so that single dot properties can be measured. An atomic force microscope (AFM) can be used to spatially access individual dots, and by applying a voltage between cantilever tip and back-electrode, the energy levels of individual dots can be measured as electrons are added to the dot one-by-one in the Coulomb blockade regime. The oscillating cantilever in these experiments is responsible for both loading the dots through electrical gating and also detecting tunneling events through a change in cantilever resonance frequency and/or cantilever dissipation. We use an AFM to measure the energy levels in few electron self-assembled InAs quantum dots. The charging energy, level spacing, and shell structure of single dots are extracted experimentally. We compare our results to a theoretical model that describes in detail the mechanism behind the dissipative electrostatic interaction due to the tunneling single-electrons.Examples of the electrostatic influence of the environment on the dots are also presented, and a method for using an AFM for characterizing electrostatic noise is demonstrated. Charge fluctuations are known to compromise the operation of electronic devices, especially for electrical components which are built in the micron and nano regime. Super bandgap irradiation leads to generation-recombination noise over the sample surface but not over the self-assembled quantum dots. We measure the generation-recombination noise with an AFM and compare the noise on and off the dot to show sub-20~nm spatial resolution, demonstrating the ability of AFM for characterizing noise arising from charge fluctuations within the sample with high spatial resolution.<br>La propriété qu'ont les points quantiques de confiner des charges élémentaires à des niveaux discrets d'énergie en font une plate-forme prometteuse pour la conception de nouveaux appareils électroniques et opto-électroniques. Les points quantiques auto-assemblés sont d'autant plus intéressants puisque leur taille, forme et matériau peuvent être contrôlés lors de leur croissance. Ces propriétés influencent le potentiel de confinement modifiant ainsi les niveaux d'énergies du point quantique. Toutefois, cette méthode de croissance ne permet pas de positionner les points quantiques et ceux-ci se retrouvent distribués aléatoirement sur la surface de l'échantillon. Cela rend difficile l'accès aux points quantiques par des techniques lithographiques pour effectuer des mesures de transport ou de détection de charge permettant d'en déterminer les propriétés.Un microscope à force atomique (AFM) permet d'accéder spatialement à des points quantiques individuels et en appliquant une tension électrique entre la pointe du cantilever et une électrode arrière, leurs niveaux d'énergies peuvent être mesurés au fur et à mesure que des électrons sont ajoutés dans un régime de blocage de Coulomb. Dans ces expériences, le cantilever oscillant est responsable simultanément du chargement des points par l'application d'une tension de grille et de la détection du passage d'électron par « effet tunnel » par un changement de fréquence de résonance et/ou de dissipation du cantilever.Nous utilisons un AFM pour mesurer les niveaux d'énergie dans des points quantiques à quelques électrons d'InAs auto-assemblés. L'énergie de chargement, l'espacement des niveaux et la configuration électronique de points individuels sont obtenus expérimentalement. Nous comparons nos résultats à un modèle théorique qui décrit en détail le mécanisme derrière l'interaction électrostatique dissipative due au passage d'électrons par « effet tunnel ».Des exemples de l'influence électrostatique de l'environnement sur les points quantiques sont aussi présentés, ainsi qu'une méthode pour utiliser l'AFM pour caractériser le bruit électrostatique. Les fluctuations de charge sont connues pour compromettre le bon fonctionnement des appareils électroniques et particulièrement des composants micro et nanométriques. L'irradiation de larges bandes d'énergie interdites produit un bruit de génération et de recombinaison à la surface de l'échantillon, mais pas sur les points quantiques auto-assemblés. Nous mesurons ce bruit avec un AFM et comparons les résultats obtenus sur la surface du point quantique et en dehors en démontrant qu'une résolution spatiale inférieure à 20 nm est réalisée. Nous démontrons ainsi qu'un AFM permet de caractériser le bruit provenant des fluctuations de charge d'un échantillon avec une haute résolution spatiale.
21
Peters-Libeu, Clare Ann. "Structural and electrostatic contributions to differences in oxidation-reduction potentials of two mutants of the copper protein, pseudoazurin /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5683.
Full text
22
Dhanabalan, Abirami. "Tin Oxide Based Composites Derived Using Electrostatic Spray Deposition Technique as Anodes for Li-Ion Batteries." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/801.
Full textAbstract:
Recent advances in the electric & hybrid electric vehicles and rapid developments in the electronic devices have increased the demand for high power and high energy density lithium ion batteries. Graphite (theoretical specific capacity: 372 mAh/g) used in commercial anodes cannot meet these demands. Amorphous SnO2 anodes (theoretical specific capacity: 781 mAh/g) have been proposed as alternative anode materials. But these materials have poor conductivity, undergo a large volume change during charging and discharging, large irreversible capacity loss leading to poor cycle performances.
To solve the issues related to SnO2 anodes, we propose to synthesize porous SnO2 composites using electrostatic spray deposition technique. First, porous SnO2/CNT composites were fabricated and the effects of the deposition temperature (200,250, 300 oC) & CNT content (10, 20, 30, 40 wt %) on the electrochemical performance of the anodes were studied. Compared to pure SnO2 and pure CNT, the composite materials as anodes showed better discharge capacity and cyclability. 30 wt% CNT content and 250 oC deposition temperature were found to be the optimal conditions with regard to energy capacity whereas the sample with 20% CNT deposited at 250 oC exhibited good capacity retention. This can be ascribed to the porous nature of the anodes and the improvement in the conductivity by the addition of CNT. Electrochemical impedance spectroscopy studies were carried out to study in detail the change in the surface film resistance with cycling. By fitting EIS data to an equivalent circuit model, the values of the circuit components, which represent surface film resistance, were obtained. The higher the CNT content in the composite, lower the change in surface film resistance at certain voltage upon cycling. The surface resistance increased with the depth of discharge and decreased slightly at fully lithiated state.
Graphene was also added to improve the performance of pure SnO2 anodes. The composites heated at 280 oC showed better energy capacity and energy density. The specific capacities of as deposited and post heat-treated samples were 534 and 737 mAh/g after 70 cycles. At the 70th cycle, the energy density of the composites at 195 °C and 280 °C were 1240 and 1760 Wh/kg, respectively, which are much higher than the commercially used graphite electrodes (37.2-74.4 Wh/kg). Both SnO2/CNTand SnO2/grapheme based composites with improved energy densities and capacities than pure SnO2 can make a significant impact on the development of new batteries for electric vehicles and portable electronics applications.
23
Mukai, Toshifumi. "Study of Hemispherical Electrostatic Analyzers and Its Application to Rocket and Satellite Observations of Low Energy Electrons." Kyoto University, 1986. http://hdl.handle.net/2433/162202.
Full text
24
Rahman, M. Shafiqur. "A Hybrid Technique of Energy Harvesting from Mechanical Vibration and Ambient Illumination." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2220.
Full textAbstract:
Hybrid energy harvesting is a concept applied for improving the performance of the conventional stand-alone energy harvesters. The thesis presents the analytical formulations and characterization of a hybrid energy harvester that incorporates photovoltaic, piezoelectric, electromagnetic, and electrostatic mechanisms. The initial voltage required for electrostatic mechanism is obtained by the photovoltaic technique. Other mechanisms are embedded into a bimorph piezoelectric cantilever beam having a tip magnet and two sets of comb electrodes on two sides of its substructure. All the segments are interconnected by an electric circuit to generate combined output when subjected to vibration and solar illumination. Results for power output have been obtained at resonance frequency using an optimum load resistance. As the power transduced by each of the mechanisms is combined, more power is generated than those obtained by stand-alone mechanisms. The synergistic feature of this research is further promoted by adding fatigue analysis using finite element method.
25
Wilhelm, Patrick Udo [Verfasser], and Andreas [Akademischer Betreuer] Wolf. "First Studies of Low-Energy Electron Cooling of keV Energy Ion Beams at the Electrostatic Cryogenic Storage Ring CSR / Patrick Udo Wilhelm ; Betreuer: Andreas Wolf." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1191758532/34.
Full text
26
Green, David Francis 1975. "Optimization of electrostatic binding free energy : applications to the analysis and design of ligand binding in protein complexes." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16888.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2002.<br>Vita.<br>Includes bibliographical references (p. 279-298).<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Electrostatic interactions play an important role in determining the energetics of association in biomolecular complexes. Previous work has shown that, within a continuum electrostatic model, for any given complex there exists a ligand charge distribution which optimizes the electrostatic binding free energy - the electrostatic complement of the target receptor. This electrostatic affinity optimization procedure was applied to several systems both in order to understand the role of electrostatic interactions in natural systems and as a tool in the design of ligands with improved affinity. Comparison of the natural and optimal charges of several ligands of glutaminyl-tRNA synthetase from E. coli, an enzyme with a strong natural requirement for specificity, shows remarkable similarity in many areas, suggesting that the optimization of electrostatic interactions played a role in the evolution of this system. The optimization procedure was also applied to the design of improvements to two inhibitors of HIV-1 viral-cell membrane fusion. Two tryptophan residues that are part of a D-peptide inhibitor were identified as contributing most significantly to binding, and a novel computational screening procedure based on the optimization methodology was developed to screen a library of tryptophan derivatives at both positions. Additionally, the optimization methodology was used to predict four mutations to standard amino acids at three positions on 5-Helix, a protein inhibitor of membrane fusion. All mutations were computed to improve the affinity of the inhibitor, with a five hundred-fold improvement calculated for one triple mutant.<br>(cont.) In the complex of b-lactamase inhibitor protein with TEM1 b-lactamase, a novel type of electrostatic interaction was identified, with surface exposed charged groups on the periphery of the binding interface projecting significant energetic effects through as much as 10 A of solvent. Finally, a large number of ab initio methods for determining partial atomic charges on small molecules were evaluated in terms of their ability to reproduce experimental values in continuum electrostatic calculations, with several preferred methods identified.<br>by David Francis Green.<br>Ph.D.
27
Vogel, Stephen [Verfasser], and Andreas [Akademischer Betreuer] Wolf. "Developments at an Electrostatic Cryogenic Storage Ring for Electron-Cooled keV Energy Ion Beams / Stephen Vogel ; Betreuer: Andreas Wolf." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180610571/34.
Full text
28
Silva, Ruy Pepe da. "Transporte de partículas e energia no plasma do tokamak TBR-1: diagnósticos e estudo experimental." Universidade de São Paulo, 1989. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-16122013-153129/.
Full textAbstract:
Os estudos sobre o plasma na região da borda de máquinas tokamak têm se intensificado nos últimos anos em decorrência da constatação de que o comportamento do plasma na região central da máquina é bastante influenciado por processos que ocorrem na borda da coluna. Neste trabalho feito um estudo experimental das propriedades de transporte do plasma na região da sombra do limitador do TBR-l, um tokamak de pequeno porte em operação no Instituto de Física da Universidade de São Paulo. São também determinados os tempos de confinamento globais de partículas e energia. Três foram os diagnósticos usados neste trabalho. Inicialmente, é abordada a utilização de sondas de Langmuir para a obtenção de perfis radiais e temporais da temperatura de elétrons, densidade e potencial de plasma; descreve-se também o arranjo experimental usado para este diagnóstico. A seguir, discute-se o projeto e a construção de uma sonda sensível a íons associada a um sistema eletrônico que permitiu a determinação simultânea das temperaturas locais de íons e elétrons. Finalmente, é discutido o dimensionamento e a implantação de um interferômetro de microondas para medidas de densidade de elétrons na região central da coluna de plasma do TBR-1; o sistema opera em 65 GHz e toda a eletrônica associada foi projetada e construída em nosso Laboratório. Os resultados obtidos com as sondas foram analisados com o ajuda de um modelo não colisional de transporte de partículas e energia para a região da sombra do limitador de máquinas tokamak. A partir dos decaimentos radiais da termperatura de elétrons (\'lâmbda IND. e\' \'APROXIMADAMENTE IGUAL A\' 2,6cm) e da densidade (\'lâmbda IND. n\' \'APROXIMADAMENTE IGUAL A\' 1,4cm), bem como do fator de transmissão de energia para os elétrons (\'delta IND. e\' \'APROXIMADAMENTE IGUAL A\' 4), determinou-se o coeficiente de difusão perpendicular ao campo magnético (\'D IND. 1\' \'APROXIMADAMENTE IGUAL A\' 6 \'m POT. 2\'\'s POT. -1\') e a difusividade térmica dos elétrons (\'qui POT. e IND. 1\' \'APROXIMADAMENTE IGUAL A\' 8 \'m POT. 2\'\'s POT. -1\'), resultados que indicam valores próximos aos previstos pelo modelo de Bohm. As medidas das temperaturas de íons e elétrons mostram um claro desacoplamento térmico entre íons e elétrons (\'T IND. i\'/\'T IND. e\' \'APROXIMADAMENTE IGUAL A\' 2). As medidas de densidade obtidas no centro da coluna, em conjunto com as obtidas na borda, permitiram a determinação dos tempos de confinamento globais de partículas (\'tau IND. p\'\'APROXIMADAMENTE IGUAL A\' 1,8 x \'10 POT. -3\'s) e de energia (\'tau IND. E\'\'APROXIMADAMENTE IGUAL A\' 1,2 x \'10 POT. -4\'s). Os resultados foram comparados com os previstos por várias leis de escala.<br>The study of the plasma edge in Tokamak machines has increased in recent last years, since the recognition that the behavior of the plasma core is influenced by the Physical processes that occur in the edge region. This work develops an experimental stud) of plasma transport properties in the shadow region of TBR-l limiter. TBR-l is a small Tokamak in operation in the Physics Institute of São Paulo University. We have also determined the global confinement time of particles and energy. We have used three diagnostics: a Langmuir probe, an ion sensitive probe, and a microwave interferometer. Initially we discuss the use of Langmuir probes in Tokamak machines to obtain temporal and radial profiles of electron temperature, plasma density and potential; we show also the experimental arrangement used in the TBR-l for this diagnostic. Then, we discuss the design and construction of an ion sensitive probe associated with an electronic system, that was used to obtain, simultaneously, local ion and electron temperature. Finally we discuss a microwave interferometry system that has been built for the TBR-1. The microwave generator is a reflex Klystron (f = 65 GHz), and with the interferometer we obtained electron density time profiles of the center of TBR-l plasma column. All the electronics associated with the interferometer were designed and built in our laboratory. The results obtained with the probes are discussed with the help of a collisionless model for Tokamak scrape-off plasma. With the radial e-foldings of electron temperature (e 2.6 cm) and density (n 1.4 cm), and the sheath electron transmission coefficient (e 4) we have determined the cross-field diffusion coefficient (D1 6 m2s-1) and the electron cross-field thermal diffusivity (e1 8 m2s-1). These results indicate values near those predicted by the Bohm model. The measurements of electron and ion temperature shows a clear thermal decoupling between ions and electrons (T1/Te 2). The measurements of plasma parameters in the center of the plasma column, with that obtained with the probes permitted the determination of the particle (p 1.8 x 10-3s) and energy (e 1.2 x10-4s) global confinement times. These results were compared with those predicted by scaling laws.
29
Kuzema, O. S., and P. O. Kuzema. "Ion Probe with Primary ion Beam Prism Mass Separator." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35627.
Full textAbstract:
It has been considered the ion-optical properties and characteristics of ion microprobe analyzer in which the primary ion beam mass separation is realized by the magnetic prism, and the beam spherical capacitor is used in the secondary ion analyzing system as energy analyzer which form parallel ion beam at the mass analyzer inlet. It has allowed to improve the instrument parameters and to scale down its overall dimension.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35627
30
Tran, Ngoc Quang. "Optimisation of indoor environmental quality and energy consumption within office buildings." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/64114/1/Ngoc%20Quang_Tran_Thesis.pdf.
Full textAbstract:
This research investigated airborne particle characteristics and their dynamics inside and around the envelope of mechanically ventilated office buildings, together with building thermal conditions and energy consumption. Based on these, a comprehensive model was developed to facilitate the optimisation of building heating, ventilation and air conditioning systems, in order to protect the health of their occupants and minimise the energy requirements of these buildings.
31
Wei, Jie. "Circuits de récupération d’énergie très basse puissance pour transducteurs à capacité variable." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS220.
Full textAbstract:
La récupération d'énergie mécanique de vibration à l’aide de transducteurs à capacité variable mène à l’étude de systèmes non linéaires complexes, mais présente des perspectives applicatives très prometteuses. Notre travail a porté sur l’étude d’une nouvelle famille de circuits d'interface pour transducteurs capacitifs. Entre autres avantages, ces circuits sont réalisables avec des rendements élevés à très basse puissance, typiquement dès quelques dizaines de nano-watts de puissance moyenne, ce qui les distingue des solutions présentées dans de l’état de l’art. De plus, Les circuits étudiés dans cette thèse ne contiennent aucun composant magnétique, ce qui constitue un atout considérable en termes de miniaturisation et d’intégration et permet eu outre la compatibilité avec l’imagerie par résonance magnétique. Les différentes structures qui constituent la famille de circuits proposés permettent de répondre à différentes contraintes imposées par le transducteur capacitif, en particulier le rapport des capacités maximale et minimale Cmax/Cmin. A partir d’une tension de sortie donnée, la tension appliquée sur le transducteur capacitif peut être modifiée en utilisant différents circuits ou en utilisant un circuit unique dont la topologie est modifiée à l’aide d’un interrupteur électronique. Les modèles théoriques développés prennent en compte le couplage électromécanique du transducteur de manière à décrire le comportement global des systèmes étudiés. Les circuits étudiés ont été validés expérimentalement avec deux transducteurs capacitifs de structure différente. En pratique, le rendement de ces circuits est proche de 80% pour des puissances converties aussi basses que la centaine de nano watts<br>The mechanic vibration energy harvesting using variable capacitance transducers leads to the study of complex nonlinear systems but has very promising application perspectives. Our work focused on the study of a new family of interface circuits for capacitive transducers. Among all the advantages, these circuits are achievable with high efficiencies at very low power, typically a few tens of nanowatts average power, which distinguishes them from the solutions presented in the state of the art. Moreover, the circuits studied in this thesis do not contain any magnetic components, which is a considerable asset in terms of miniaturization and integration and also allows compatibility with magnetic resonance imaging. The various structures which constitute the family of circuits proposed make it possible to satisfy various constraints imposed by the capacitive transducer, in particular, the ratio of the maximum and minimum capacities Cmax / Cmin. For a given output voltage, the voltage applied to the capacitive transducer can be varied by using different circuits or by using a single circuit whose topology is modified by the operation of an electronic switch. In order to describe the overall behavior of the studied systems, the electromechanical coupling of the transducer is taken into account in the developed theoretical models. The studied circuits have been validated experimentally with two capacitive transducers of different structure. In practice, the output of these circuits is close to 80% for converted powers as low as the hundred nanowatts
32
Deterre, Martin. "Toward an energy harvester for leadless pacemakers." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00868838.
Full textAbstract:
This work consists in the development and design of an energy harvesting device to supply power to the new generation pacemakers, miniaturized leadless implants without battery placed directly in heart chambers. After analyzing different mechanical energy sources in the cardiac environment and associated energy harvesting mechanisms, a concept based on regular blood pressure variation stood out: an implant with a flexible packaging that transmits blood forces to an internal transducer. Advantages compared to traditional inertial scavengers are mainly: greater power density, adaptability to heartbeat frequency changes and miniaturization potential. Ultra-flexible 10-µm thin metal bellows have been designed, fabricated and tested. These prototypes acting as implant packaging that deforms under blood pressure actuation have validated the proposed harvesting concept. A new type of electrostatic transducer (3D multi-layer out-of-plane overlap structure with interdigitated combs) has been introduced and fully analyzed. Promising numerical results and associated fabrication processes are presented. Also, large stroke optimized piezoelectric spiral transducers including their complex electrodes patterns have been studied through a design analysis, numerical simulations, prototype fabrication and experimental testing. Apower density of 3 µJ/cm3/cycle has been experimentally achieved. With further addressed developments, the proposed device should provide enough energy to power autonomously and virtually perpetually the next generation of pacemakers.
33
Borany, Johannes von, and Jochen Teichert. "Entwicklung einer Niederenergie-Implantationskammer mit einem neuartigen Bremslinsensystem." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-29706.
Full textAbstract:
In diesem Report wird eine Niederenergie-Implantationskammer (NEI-Kammer) beschrieben, die im Forschungszentrum Rossendorf entwickelt und aufgebaut wurde. Die Kammer ermöglicht es, die Implantation von Ionen bei niedrigen Energien (< 30 keV) mit einer Implantationsanlage für mittlere Energien durchzuführen. In der Kammer werden der Ionenstrahl, den der Implanter liefert, auf die erwünschte niedrige Energie abgebremst. Dazu wird ein elektrostatisches Bremslinsensystem eingesetzt, das auf einem neuartigen Prinzip basiert. Das System besteht aus einer Sammellinse und einer Zerstreuungslinse, wobei die Öffnungsfehler beider Linsen entgegengesetzte Vorzeichen besitzen und sich gegenseitig kompensieren. Dadurch ist es möglich, Wafer gebräuchlicher Größe bei geringer Energie mit hoher Dosishomogenität zu implantieren. Die NEI-Kammer ist insbesondere für Forschungseinrichtungen eine vorteilhafte Lösung, da sie eine wesentlich kostengünstigere und flexiblere Alternative zur Anschaffung einer Niederenergie-Implantationsanlage darstellt.
34
Borany, Johannes von, and Jochen Teichert. "Entwicklung einer Niederenergie-Implantationskammer mit einem neuartigen Bremslinsensystem." Forschungszentrum Rossendorf, 2001. https://hzdr.qucosa.de/id/qucosa%3A21797.
Full textAbstract:
In diesem Report wird eine Niederenergie-Implantationskammer (NEI-Kammer) beschrieben, die im Forschungszentrum Rossendorf entwickelt und aufgebaut wurde. Die Kammer ermöglicht es, die Implantation von Ionen bei niedrigen Energien (< 30 keV) mit einer Implantationsanlage für mittlere Energien durchzuführen. In der Kammer werden der Ionenstrahl, den der Implanter liefert, auf die erwünschte niedrige Energie abgebremst. Dazu wird ein elektrostatisches Bremslinsensystem eingesetzt, das auf einem neuartigen Prinzip basiert. Das System besteht aus einer Sammellinse und einer Zerstreuungslinse, wobei die Öffnungsfehler beider Linsen entgegengesetzte Vorzeichen besitzen und sich gegenseitig kompensieren. Dadurch ist es möglich, Wafer gebräuchlicher Größe bei geringer Energie mit hoher Dosishomogenität zu implantieren. Die NEI-Kammer ist insbesondere für Forschungseinrichtungen eine vorteilhafte Lösung, da sie eine wesentlich kostengünstigere und flexiblere Alternative zur Anschaffung einer Niederenergie-Implantationsanlage darstellt.
35
Bedier, Mohammed. "Circuits d’interface intégrés sur silicium pour une gestion optimale de la puissance dans les récupérateurs d’énergie vibratoire à transduction capacitive." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066376/document.
Full textAbstract:
Les vibrations ambiantes representent une source potentielle d'energie pour alimentation des capteurs sans fil autonomes. La transduction electrostatique est une des techniques utilisees pour la conversion de l'energie des vibrations en electricite. De nombreuses realisations des transducteurs et leurs circuits de conditionnement ont deja ete presentees dans la litterature. Pour transmettre l'energie convertie vers une charge utile des interfaces specifiques doivent etre concues. Ce dernier sujet a ete peu aborde dans la litterature. Ce travail etudie une interface avec la charge dans un dispositif de recuperation d'energie vibratoire. L'architecture proposee au cours de cette etude est adaptee aux circuits de conditionnement de type pompe de charge, qui fonctionne selon un cycle charge-tension rectangulaire. L'interface proposee accomplit deux taches. Premierement, il permet de transferer l'energie electrique du circuit de conditionnement vers une charge tout en abaissant la tension d'une maniere adiabatique, c.a.d., en minimisant les dissipations. Deuxiemement, il permet de reguler le debit d'extraction d'energie du circuit de conditionnement en ajustant dynamiquement la puissance de ce transfert. Cela est realise avec un circuit integree en technologie 0.35um CMOS haute tension dont l'architecture est inspiree d'un convertisseur DCDC de type Buck fonctionnant en regime discontinu. La consommation de l'interface est minimisee grace a l'utilisation du regime sous le seuil des transistors MOS pour pratiquement tous les blocs, grace a une alimentation reduite a 1.1V. L'interface consomme en dessous de 100nW, et est capable de gerer des sources d'energie a puissance < 1uW<br>Vibrational energy is an attractive power source for self-powered wireless sensors. A mainstream harvesting technique for vibrational energy is electrostatic MEMS harvesters. Various circuit architectures have already been introduced with many successful implementation, yet a load interface that efficiently manages the harvested energy has rarely been reported. In this work a load interface is proposed which is suited for any condition circuit (CC) implementing rectangular QV cycles. In general, a rectangular QV conditioning circuit has an optimum interval of which the energy harvested is maximised, thus the harvested energy should be periodically removed to maintain maximising the harvested energy. This is achieved through the load interface (LI). The LI proposed is a switched inductor capacitive architecture with a LI controller allowing the extraction of the energy in a multiple energy shot fashion. The LI controller incorporate an ultra low power clock for switching events and low power comparator for switching decision. Power consumption is reduced by operating at a low supply voltage (1.1V). The LI is implemented in AMS0.35HV technology with a mixed high voltage-low power control blocks. It takes into account the harvester operation to maximise its extracted energy. It overcomes the constrained limited biasing power, tackles resistive losses and power handling transistor long channels by transferring the energy in a multiple shots fashion. A CMOS implementation is proposed along with simulation results showing an average consumed power of the controller less than 100nW allowing the system to operate with input power levels as low as few hundreds of nano-watts
36
Wijngaart, Wouter van der. "Designing Microfluidic Control Components." Doctoral thesis, KTH, Signals, Sensors and Systems, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3352.
Full text
37
Kumar, Pushpendra. "Impact of 14/28nm FDSOI high-k metal gate stack processes on reliability and electrostatic control through combined electrical and physicochemical characterization techniques." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT114/document.
Full textAbstract:
Cette thèse concerne l’étude des procédés de fabrication des grilles HKMG des technologies FDSOI 14 et 28 nm sur les performances électriques des transistors MOS. Elle a porté spécifiquement sur l'aspect fiabilité et la maîtrise du travail de sortie effectif (WFeff), au travers de la diffusion des additifs comme le lanthane (La) et l’aluminium (Al). Ce travail combine des techniques de caractérisation électriques et physico-chimiques et leur développement. L'effet de l'incorporation de ces additifs sur la fiabilité et la durée de vie du dispositif a été étudié. Le lanthane dégrade les performances de claquage TDDB et de dérives suite aux tests aux tensions négatives. L’introduction d’aluminium améliore le claquage TDDB, mais dégrade les dérives aux tensions positives. Ces comportements ont été reliés à des mécanismes physiques. Par ailleurs, la diffusion de ces additifs dans l’empilement de grille a été étudiée pour différents matériaux high-k en fonction de la température et de la durée de recuit de diffusion. Les doses d’additifs ont pu être ainsi mesurées, comparées et corrélées au décalage de travail de sortie effectif de grille. On a également étudié, les influences des paramètres du procédé de dépôt de grille TiN sur leur microstructure et les propriétés électriques du dispositif, identifiant certaines conditions à même de réduire la taille de grain ou la dispersion d’orientation cristalline. Toutefois, les modulations obtenues sur le travail de sortie effectif de grille dépendent plus du ratio Ti/N, suggérant un changement du dipôle à l'interface SiO2 / high-k. Enfin, une technique éprouvée de mesure de spectroscopie à rayon X sous tension a pu être mise en place grâce des dispositifs spécifiques et une méthodologie adaptée. Elle permet de mesurer les positions relatives des bandes d’énergie à l'intérieur de l’empilement de grille. Cette technique a démontré que le décalage du travail de sortie effectif induits par des additifs (La or Al) ou par des variations d'épaisseur de grille métallique TiN provient de modifications du dipôle à l'interface SiO2/ high-k<br>This Ph.D. thesis is focused on the impact of the 14 and 28 nm FDSOI technologies HKMG stack processes on the electrical performance of MOS transistors. It concerns specifically the reliability aspect and the engineering of effective workfunction (WFeff ), through diffusion of lanthanum (La) and aluminum (Al) additives. This work combines electrical and physicochemical characterization techniques, and their development. The impact of La and Al incorporation, in the MOS gate stack, on reliability and device lifetime has been studied. La addition has a significant negative impact on device lifetime related to both NBTI and TDDB degradations. Addition of Al has a significant negative impact on lifetime related to PBTI, but on the contrary improves the lifetime for TDDB degradation. These impacts on device lifetime have been well correlated to the material changes inside the gate oxides. Moreover, diffusion of these additives into the HKMG stack with annealing temperature and time has been studied on different high-k materials. The diffused dose has been compared with the resulting shift in effective workfunction (WFeff), evidencing clear correlation. In addition, impact of TiN metal gate RF-PVD parameters on its crystal size and orientation, and device electrical properties has been studied. XRD technique has been used to obtain the crystal size and orientation information. These properties are significantly modulated by TiN process, with a low grain size and a unique crystal orientation obtained in some conditions. However, the WFeff modulations are rather correlated to the Ti/N ratio change, suggesting a change in the dipole at SiO2/high-k interface. Lastly, using specific test structures and a new test methodology, a robust and accurate XPS under bias technique has been developed to determine the relative band energy positions inside the HKMG stack of MOS devices. Using this technique, we demonstrated that WFeff shift induced by La and Al or by variations in gate thickness originates due to modifications of the dipole at SiO2/high-k interface
38
Hartmann, R. (Robert). "Flotation using cellulose-based chemicals." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526219806.
Full textAbstract:
Abstract Flotation is a well-known and widely used technique for the separation of particles smaller than 250 µm, but efficient performance requires the use of various synthetic chemicals which can potentially damage the health of humans and animals and pollute the environment. Consequently, their replacement through a more environment-friendly and sustainable alternative has been demanded. One promising candidate is cellulose, which is an abundant natural polymer that is environment-friendly and can be treated chemically and physically to yield tailored properties and thus a potential for use in processes such as flotation. This work focuses on the use of cellulose-based reagents in flotation processes to replace the often harmful conventional reagents derived from mineral oil, plant oils or animal fats. The physico-chemical properties of cellulose differ from those of conventional reagents, leading to differences in performance during flotation. In particular, the chemical and morphological heterogeneity of cellulose affects its properties and thus its interaction with minerals and water. Consequently, its use requires the study of the fundamentals of flotation and their application including the physico-chemical heterogeneity of cellulose to determine the optimum conditions and enable efficient performance. This work focuses on the determination of the thermodynamic surface energetics of solid particles and changes in this after reagent adsorption, using the inverse gas chromatography technique in a dry atmosphere. Furthermore, interactions between cellulose and minerals immersed in water are investigated using the DLVO theory, the interaction forces between cellulose and the minerals being derived and correlated with flotability. The importance of free surface charges is then considered by investigating the electric surface potential of cellulose-coated minerals in connection with particle-bubble attachment efficiency. At the same time, conventional amphiphilic reagents are used and its performances are related to cellulose-based reagents<br>Tiivistelmä Vaahdotus on kaivannaisteollisuudessa laajasti käytössä oleva prosessi, jonka avulla saadaan erotettua tehokkaasti pieniä, alle 250 µm kokoisia partikkeleita. Vaahdotuksen apuaineena käytetään erilaisia synteettisiä kemikaaleja, jotka voivat aiheuttaa harmia ympäristölle. Siksi niiden korvaaminen ympäristöystävällisemmillä vaihtoehdoilla on tärkeää. Yksi lupaava vaihtoehto korvaavaksi materiaaliksi on selluloosa. Selluloosa on uusiutuva ja ympäristöystävällinen luonnonpolymeeri, josta voidaan valmistaa kemiallisesti ja fysikaalisesti käsittelemällä erilaisia biokemikaaleja. Näitä voidaan soveltaa erilaisissa prosesseissa, myös vaahdotuksessa. Tässä työssä keskitytään selluloosapohjaisten kemikaalien käyttöön vaahdotuksessa tavanomaisten, usein haitallisten synteettisten kemikaalien korvaamiseksi. Selluloosan fysikaaliskemialliset ominaisuudet eroavat synteettisten vaahdotuskemikaalien ominaisuuksista, mikä vaikuttaa niiden vuorovaikutukseen mineraalien ja veden kanssa. Erityisesti selluloosan kemiallinen ja morfologinen heterogeenisuus on keskeinen tekijä. Selluloosan hyödyntäminen tulevaisuuden vaahdotuskemikaalina edellyttää selluloosan ja mineraalien vuorovaikutuksen syvällistä ymmärtämistä. Tässä työssä tutkitaan selluloosan ja mineraalien vuorovaikutusta sekä IGC-menetelmän avulla, että DLVO-teorian että pintavarausmittausten avulla. Lisäksi tutkitaan selluloosan ja mineraalien vuorovaikutusvoimien yhteyttä vaahdotusprosessin onnistumiseen ja saavutettuja tuloksia verrataan kaupallisten reagenssien toimintaan
39
Stoyanov, Hristiyan. "Soft nanocomposites with enhanced electromechanical response for dielectric elastomer actuators." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5119/.
Full textAbstract:
Electromechanical transducers based on elastomer capacitors are presently considered for many soft actuation applications, due to their large reversible deformation in response to electric field induced electrostatic pressure. The high operating voltage of such devices is currently a large drawback, hindering their use in applications such as biomedical devices and biomimetic robots, however, they could be improved with a careful design of their material properties. The main targets for improving their properties are increasing the relative permittivity of the active material, while maintaining high electric breakdown strength and low stiffness, which would lead to enhanced electrostatic storage ability and hence, reduced operating voltage. Improvement of the functional properties is possible through the use of nanocomposites. These exploit the high surface-to-volume ratio of the nanoscale filler, resulting in large effects on macroscale properties.
This thesis explores several strategies for nanomaterials design. The resulting nanocomposites are fully characterized with respect to their electrical and mechanical properties, by use of dielectric spectroscopy, tensile mechanical analysis, and electric breakdown tests. First, nanocomposites consisting of high permittivity rutile TiO2 nanoparticles dispersed in thermoplastic block copolymer SEBS (poly-styrene-coethylene-co-butylene-co-styrene) are shown to exhibit permittivity increases of up to 3.7 times, leading to 5.6 times improvement in electrostatic energy density, but with a trade-off in mechanical properties (an 8-fold increase in stiffness). The variation in both electrical and mechanical properties still allows for electromechanical improvement, such that a 27 % reduction of the electric field is found compared to the pure elastomer. Second, it is shown that the use of nanofiller conductive particles (carbon black (CB)) can lead to a strong increase of relative permittivity through percolation, however, with detrimental side effects. These are due to localized enhancement of the electric field within the composite, which leads to sharp reductions in electric field strength. Hence, the increase in permittivity does not make up for the reduction in breakdown strength in relation to stored electrical energy, which may prohibit their practical use. Third, a completely new approach for increasing the relative permittivity and electrostatic energy density of a polymer based on 'molecular composites' is presented, relying on chemically grafting soft π-conjugated macromolecules to a flexible elastomer backbone. Polarization caused by charge displacement along the conjugated backbone is found to induce a large and controlled permittivity enhancement
(470 % over the elastomer matrix), while chemical bonding, encapsulates the PANI chains manifesting in hardly any reduction in electric breakdown strength, and hence resulting in a large increase in stored electrostatic energy. This is shown to lead to an improvement in the sensitivity of the measured electromechanical response (83 % reduction of the driving electric field) as well as in the maximum actuation strain (250 %). These results represent a large step forward in the understanding of the strategies which can be employed to obtain high permittivity polymer materials with practical use for electro-elastomer actuation.<br>Die Palette von elektro-mechanischen Aktuatoren, basierend auf dem Prinzip weicher dehnbarer Kondensatoren, scheint besonders für Anwendungen in der Medizin und für biomimetische Applikationen unbegrenzt. Diese Wandler zeichnen sich sowohl durch hohe Reversibilität bei großer mechanischer Deformation als auch durch ihre Flexibilität aus, wobei die mechanischen Deformationen durch elektrische Felder induziert werden. Die Notwendigkeit von hoher elektrischer Spannung zur Erzeugung dieser mechanischen Deformationen verzögert jedoch die technisch einfache und breite Markteinführung dieser Technologie. Diesem Problem kann durch eine gezielte Materialmodifikation begegnet werden. Eine Modifikation hat das Ziel, die relative Permittivität zu erhöhen, wobei die Flexibilität und die hohe elektrische Durchbruchsfeldstärke beibehalten werden sollten. Durch eine Materialmodifikation kann die Energiedichte des Materials bedeutend erhöht und somit die notwendige Betriebsspannung des Aktuators herabgesetzt werden. Eine Verbesserung der funktionalen Materialeigenschaften kann durch die Verwendung von Nanokompositen erzielt werden, welche die fundamentalen Eigenschaften der Nanopartikel, d.h. ein gutes Verhältnis von Oberfläche zu Volumen nutzen, um eine gezielte makroskopische Materialmodifikation zu bewirken.
Diese Arbeit behandelt die Anwendung innovativer Strategien für die Erzeugung von Nanomaterialien mit hoher Permittivität. Die so erzeugten Materialien und deren relevante Aktuatorkenngrößen werden durch elektrische und mechanische Experimente vollständig erfasst. Mittels der klassischen Mischansätze zur Erzeugung von Kompositmaterialen mit hoher Permittivität konnte durch nichtleitendes Titaniumdioxid TiO2 (Rutile) in einem Thermoplastischen-Block-Co-Polymer SEBS (poly-styrene-co-ethylene-cobutylene-co-styrene) die Permittivität bereits um 370 % erhöht und die elektrische Energiedichte um 570 % gesteigert werden. Diese Veränderungen führten jedoch zu einem signifikanten Anstieg der Steifigkeit des Materials. Aufgrund der positiven Rückkopplung von elektrischen und mechanischen Eigenschaften des Kompositmaterials ermöglicht bereits dieser einfache Ansatz eine Verbesserung der Aktuation, bei einer 27 %-igen Reduktion der Aktuatorbetriebsspannung. Eine direkte Verwendung von leitfähigen Nanopartikeln kann ebenso zu einem Anstieg der relativen Permittivität beitragen, wobei jedoch die Leitfähigkeit dieser Nanopartikel bedeutende Wechselwirkungen verursacht, welche somit die Energiedichte des Materials negativ beeinflusst und die praktische Verwendung dieses Kompositsystems ausschließt. Als ein völlig neuer Ansatz zur Steigerung der relativen Permittivität und Energiedichte und abweichend vom klassischen Mischverfahren, wird die Herstellung eines "Molekularen Komposits", basierend auf einem chemischen Propfverfahren, präsentiert. In diesem Ansatz wird ein π-konjugiertes leitfähiges Polymer (PANI) an die Hauptkette des Elastomers der Polymermatrix gebunden. Die daraus resultierende Ladungsverteilung entlang der Elastomerhauptkette bewirkt eine 470 %-ige Steigerung der Permittivität des "Molekularen Komposits" im Vergleich zur Permittivität des unbehandelten Elastomermaterials. Aufgrund der Verkapselung der chemischen Bindungen der PANI-Kette entstehen kaum negative Rückwirkungen auf die elektrischen und mechanischen Eigenschaften des so erzeugten Komposits. Diese Materialeigenschaften resultieren in einem signifikanten Anstieg der Energiedichte des Materials. Das mittels dieses Verfahrens erzeugte Komposit zeigt sowohl eine Steigerung der Sensitivität der elektromechanischen Antwort (Reduktion des elektrischen Felds um 83 %) als auch eine bedeutende Steigerung der maximalen Aktuation (250 %). Die Ergebnisse und Ideen dieser Arbeit stellen einen wesentlichen Sprung im Verständnis zur Permittivitätssteigerung in Polymermaterialien dar und werden deshalb in der Erforschung und Entwicklung von Elastomeraktuatoren Beachtung finden.
40
Schaufuß, Jörg. "Energieversorgung autarker Sensorsysteme im industriellen Umfeld durch kinetische Energiewandler mit Schwerpunkt auf dem elektrostatischen Wandlerprinzip." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-129344.
Full textAbstract:
In der vorliegenden Arbeit wird die Entwicklung eines kinetischen Energy Harvesters vorgestellt, der auf Grundlage des elektrostatischen Wandlerprinzips aus Vibrationen elektrische Energie generiert. Für die Umsetzung wurde eine Siliziummikrostruktur entworfen, die für Arbeitsfrequenzen unter 100 Hz ausgelegt ist. Die Zahnstruktur der verwendeten Elektroden ermöglicht Spaltabstände im Submikrometerbereich und folglich große Kapazitätsänderungen, die durch die Elektrodengeometrie zusätzlich mit einer höheren Frequenz als die mechanische Bewegung stattfinden. Vergleichsweise große Leistungsausbeuten und geringe Quellimpedanzen sind dadurch erreichbar. Die geometrischen Parameter der Elektroden wurden unter Berücksichtigung der auftretenden Fertigungstoleranzen und Wechselwirkungen zueinander optimiert. Für die Ausnutzung einer ausreichend großen Inertialmasse wurde ein feinwerktechnisch hergestellter Hebelmechanismus an die Mikrostruktur angekoppelt. Über diesen wird zusätzlich ein neuer Ansatz zur Abstimmung der Eigenfrequenz des Harvesters umgesetzt. Experimentelle Untersuchungen zeigten Ausgangsleistungen im einstelligen Mikrowattbereich bei Anregungen im Zehntel m/s²-Bereich. Durch fortschreitende Optimierungen der Fertigungstechnologie sind noch deutliche Leistungssteigerungen um mindestens zwei Größenordnungen möglich. Weiterhin wird ein Energiemanagementsystem vorgestellt, welches die effiziente Übertragung der Energie auf den Verbraucher ermöglicht<br>In this work the development of a kinetic energy harvester using the electrostatic conversion principle is presented. The silicon microstructure is designed to work in frequency ranges below 100Hz. Its toothed electrode structure enables gap distances in the sub micrometer range and consequently high changes of capacitance. Additionally, due to the electrode geometry the frequency of the capacitance changes is higher then the frequency of the mechanical movement. Thus high power outputs and low source impedances can be reached. The electrodes geometric parameters were optimized considering manufacturing tolerances and interactions of the parameters. To reach a sufficient inertial mass, a lever mechanism manufactured by precision engineering was connected to the microstructure. This mechanism also allows the implementation of a new method of frequency tuning. In experimental tests power outputs in the single digit microwatt range under excitations of 0.3 m/s² were reached. In accordance of further optimizations of the manufacturing technology significantly higher outputs, by at least two orders of magnitude, are possible,. Furthermore an energy management system is presented, that allows the efficient transfer of the electrical energy to the consumer
41
Bedier, Mohammed. "Circuits d’interface intégrés sur silicium pour une gestion optimale de la puissance dans les récupérateurs d’énergie vibratoire à transduction capacitive." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066376.
Full textAbstract:
Les vibrations ambiantes representent une source potentielle d'energie pour alimentation des capteurs sans fil autonomes. La transduction electrostatique est une des techniques utilisees pour la conversion de l'energie des vibrations en electricite. De nombreuses realisations des transducteurs et leurs circuits de conditionnement ont deja ete presentees dans la litterature. Pour transmettre l'energie convertie vers une charge utile des interfaces specifiques doivent etre concues. Ce dernier sujet a ete peu aborde dans la litterature. Ce travail etudie une interface avec la charge dans un dispositif de recuperation d'energie vibratoire. L'architecture proposee au cours de cette etude est adaptee aux circuits de conditionnement de type pompe de charge, qui fonctionne selon un cycle charge-tension rectangulaire. L'interface proposee accomplit deux taches. Premierement, il permet de transferer l'energie electrique du circuit de conditionnement vers une charge tout en abaissant la tension d'une maniere adiabatique, c.a.d., en minimisant les dissipations. Deuxiemement, il permet de reguler le debit d'extraction d'energie du circuit de conditionnement en ajustant dynamiquement la puissance de ce transfert. Cela est realise avec un circuit integree en technologie 0.35um CMOS haute tension dont l'architecture est inspiree d'un convertisseur DCDC de type Buck fonctionnant en regime discontinu. La consommation de l'interface est minimisee grace a l'utilisation du regime sous le seuil des transistors MOS pour pratiquement tous les blocs, grace a une alimentation reduite a 1.1V. L'interface consomme en dessous de 100nW, et est capable de gerer des sources d'energie a puissance < 1uW<br>Vibrational energy is an attractive power source for self-powered wireless sensors. A mainstream harvesting technique for vibrational energy is electrostatic MEMS harvesters. Various circuit architectures have already been introduced with many successful implementation, yet a load interface that efficiently manages the harvested energy has rarely been reported. In this work a load interface is proposed which is suited for any condition circuit (CC) implementing rectangular QV cycles. In general, a rectangular QV conditioning circuit has an optimum interval of which the energy harvested is maximised, thus the harvested energy should be periodically removed to maintain maximising the harvested energy. This is achieved through the load interface (LI). The LI proposed is a switched inductor capacitive architecture with a LI controller allowing the extraction of the energy in a multiple energy shot fashion. The LI controller incorporate an ultra low power clock for switching events and low power comparator for switching decision. Power consumption is reduced by operating at a low supply voltage (1.1V). The LI is implemented in AMS0.35HV technology with a mixed high voltage-low power control blocks. It takes into account the harvester operation to maximise its extracted energy. It overcomes the constrained limited biasing power, tackles resistive losses and power handling transistor long channels by transferring the energy in a multiple shots fashion. A CMOS implementation is proposed along with simulation results showing an average consumed power of the controller less than 100nW allowing the system to operate with input power levels as low as few hundreds of nano-watts
42
Svärd, Michael. "Crystal Polymorphism of Substituted Monocyclic Aromatics." Licentiate thesis, KTH, Chemical Engineering and Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10501.
Full text
43
Saddi, Zied. "Conception d'un dispositif de récupération d'énergie mixte vibratoire-électromagnétique pour l'alimentation des dispositifs à faible consommation." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1065/document.
Full textAbstract:
L’alimentation des systèmes communicants à partir des sources d’énergies existantes dans l’environnement est une solution pertinente pour prolonger leur autonomie énergétique. Cela peut permettre de s’affranchir des sources d’énergie embarquées comme les piles et les batteries, qui présentent une durée de vie limitée, nécessite un remplacement périodique et un coût de recyclage. Parmi les sources d’énergies récupérables, les ondes électromagnétiques et les vibrations mécaniques sont considérées parmi les plus prometteuses en raison de leur disponibilité notamment dans les milieux urbains. Notre contribution porte sur l’étude et la réalisation d’un dispositif de récupération d’énergie vibratoire par transduction électrostatique. Ce type de système, basé sur une variation de capacité, nécessite une tension de pré-charge provenant d’une source auxiliaire. Afin d’éviter les matériaux piézoélectriques et les électrets caractérisés par une durée de vie limité, la phase d’initialisation a été assurée par une rectenna (Rectifying antenna).Deux rectennas ont été développées pour assurer la pré-charge du transducteur électrostatique. Une première structure bi-bande (2.45 GHz et 1.8 GHz) basée sur un anneau hybride a été proposée. Elle permet, non seulement d’augmenter la puissance RF captée, mais aussi de simplifier les problèmes d’adaptation. Une tension de 320 mV et un rendement de 40.6 % ont été mesurés, respectivement pour des densités surfaciques de puissance de 1.13 et 1.87 µW/cm2 aux fréquences 1.85 et 2.45 GHz. Une deuxième structure élévatrice de tension en topologie Cockcroft-Walton a été conçue et caractérisée expérimentalement. Une tension de 1.06 V a été mesurée pour une densité surfacique de puissance de 1.55 µW/cm².Un dispositif de récupération d’énergie mixte électromagnétique vibratoire complet a été par la suite étudié, conçu et caractérisé expérimentalement. Le transducteur électrostatique a été couplé à un circuit de conditionnement de Bennet pré-chargé par la rectenna. Une tension de 23 V a été obtenue à la sortie du système pour une tension de pré-charge de 0.5 V (1.55 µW/cm²) et à partir d’une vibration mécanique de fréquence 25 Hz et une accélération 1.5g.Une modélisation du transducteur électrostatique adaptée à différentes structures a été proposée. En se basant sur les équivalences mécaniques électriques, un modèle électrique équivalent est déduit en utilisant le logiciel LTspice de façon à étudier le comportement du système et prévoir la tension et la puissance récupérée.Mots clés : récupération d’énergie, rectenna, antenne microruban, circuit de conversion RF-DC, transducteur électrostatique, circuit de conditionnement de Bennet, modélisation<br>Energy harvesting is an attractive solution to power supply low-power electronics and wireless communication devices avoiding the use of power sources like batteries which have a limited life, requires periodic replacements and have a cost of recycling. Among the available ambient energy sources, electromagnetic waves and mechanical vibrations are the most suitable because of their availability particularly in the urban areas. Our contribution focuses on the study and implementation of a vibrational energy harvesting device using the electrostatic transduction. This system, based on a capacitance modulation, requires a voltage pre-charge given by an auxiliary source. To avoid electret or piezoelectric materials characterized by a limited lifetime, the initialization step was provided by a rectenna (Rectifying antenna).A new structure of dual-band rectenna (2.45 GHz and 1.8 GHz) based on a hybrid ring has been proposed. It allows to increase the received RF power but also to simplify the matching circuit. It experimentally achieves 320 mV voltage and 40 % efficiency when the power densities are 1.13 and 1.87 mW/cm2 at 1.85 and 2.45 GHz, respectively. A Cockcroft-Walton voltage multiplier rectenna was also designed and experimentally characterized. A voltage of 1.06 V was measured at a power density of 1.55 mW/cm².A macro-scale electrostatic vibration harvester (e-VEH), wirelessly pre-charged with a 2.45 GHz Cockcroft-Walton rectenna, was studied, designed and experimentally characterized. The e-VEH uses the Bennet doubler as conditioning circuit. A voltage of 23 V across the transducer terminal has been measured when the vibration harvester is excited at 25 Hz and 1,5g of external acceleration. An energy of 275 µJ and a maximum power of 0.4 µW are available across the load. A lumped element model of the electrostatic transducer has been proposed. Based on mechanical/electrical equivalent equations, an equivalent electrical circuit is derived using the LTspice simulator to study the behavior of the system and provide the voltage and the power converted.Keywords: Energy harvesting, rectenna, microstrip antenna, RF-to-dc converter, electrostatic transduction, Bennet’s doubler, modélization
44
Risquez, Sarah. "Microsystème électrostatique tridimensionnel de récupération d'énergie pour alimenter un stimulateur cardiaque sans sonde." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS044/document.
Full textAbstract:
Cette thèse s’inscrit dans un contexte d’activité en forte croissance dans le domaine des implants médicaux, stimulée par de nombreux progrès dans le domaine des micro-capteurs et de la micro-électronique. L’autonomie en énergie des implants demeure cependant un facteur limitant. Notre travail a pour objectif de repousser les limites actuelles en termes de miniaturisation et de durée de vie. Il contribue au développement d’une solution basée sur la récupération d’énergie mécanique du cœur pour alimenter durablement un pacemaker miniaturisé sans sonde de nouvelle génération, dit « pacemaker leadless ».Le microsystème de récupération d’énergie étudié est composé d’un résonateur mécanique de type masse-ressort associé à un transducteur électrostatique. Il a pour particularité une architecture tridimensionnelle, dont la forme permet de profiter au maximum de l’espace disponible dans la capsule cylindrique du pacemaker. L'utilisation de la troisième dimension associée à un design original permet en outre d’obtenir un effet de pseudo multiplication de fréquence qui doit conduire, d’après les modèles que nous avons développés, à des densités de puissance nettement supérieures à celles présentées dans l'état de l'art. Pour réaliser ce microsystème tridimensionnel, nous avons développé un procédé de fabrication additif qui repose sur des étapes de micro moulage d'un matériaux structurel obtenu par croissance électrolytique (nickel), de croissance d'un matériau sacrificiel (cuivre) et de polissage. L’identification d’imperfections géométriques dues au procédé et aux matériaux utilisés nous a amené à améliorer la conception du transducteur. Par ailleurs, de nombreux verrous de fabrication ont été levés au cours de cette thèse grâce à la mise en œuvre d’une instrumentation dédiée. Ce procédé nous a permis de fabriquer un premier prototype tridimensionnel du micro-transducteur électrostatique composé de 10 couches de nickel. D’autres métaux élaborés par croissance électrolytique pourraient être envisagés pour réaliser des microsystèmes tridimensionnels, suivant les besoins de l’application considérée. Afin d’anticiper d’éventuels problèmes de compatibilité des micro-dispositifs avec l'imagerie par résonance magnétique, nous avons mis au point le procédé de croissance électrolytique d’un matériau non-magnétique à base de nickel dopé au phosphore<br>This thesis contributes to the medical implants field, which is stimulated by many advances in the fields of microelectronics and microsensors. However, electrical energy lifespan of implants and large size of batteries are still a problem. Our work aims at pushing back these limits. It contributes to the development of a solution based on mechanical energy harvesting from the heart motion. The objective is to sustainably power a new generation of pacemakers without lead, so-called "leadless pacemakers."The studied energy harvesting microsystem consists in a spring-mass-type mechanical resonator associated with an electrostatic transducer. Its originality comes from a three-dimensional architecture, whose shape fits pretty well with the cylindrical shape of the pacemaker capsule. The use of the third dimension combined with an original design enables to get a pseudo multiplication frequency effect. Thanks to this effect, our simulation models predict power densities significantly higher than state-of-the-art figures reported in literature. To fabricate this three-dimensional microsystem, we have developed an additive manufacturing process based on steps of micro-molding of a structural material (electroplated nickel), electroplating of a sacrificial material (copper) and planarization. Identification of imperfections related to the fabrication process and the materials used allowed us to improve the design of the transducer. Moreover, many manufacturing obstacles were overcome during this thesis through the implementation of dedicated instrumentation. This new process has enabled us to fabricate a first three-dimensional prototype of the electrostatic micro-transducer made of 10 layers of nickel. Other electroplated metals can be envisaged to achieve three-dimensional microsystems, depending on the application requirements. In order to anticipate any compatibility issue of our microsystem with magnetic resonance imaging, we have developed the electrodeposition process of a nonmagnetic material: phosphorous doped nickel
45
Guillemet, Raphaël. "Etude et réalisation d'un récupérateur d'énergie vibratoire par transduction électrostatique en technologie MEMS silicium." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1082/document.
Full textAbstract:
Une solution pertinente afin d'alimenter des capteurs isolés consiste à récupérer l'énergie disponible dans leur environnement immédiat. Parmi les sources d'énergie envisageables, notre choix s'est porté sur les vibrations mécaniques ambiantes. Notre contribution porte sur l'étude et la réalisation, par un procédé de fabrication collective, d'un transducteur électrostatique sans électrets en technologie MEMS Silicium. Nous proposons une étude analytique permettant d'optimiser l'efficacité du générateur électrostatique, tout en considérant une limite sur la tension maximale aux bornes du transducteur afin de ne pas endommager le circuit de conditionnement. Le design proposé prend également en compte d'éventuelles variations de l'amplitude des vibrations externes. Le dispositif a été fabriqué au sein de ESIEE Paris et présente un volume total de moins de 100 mm3.Les tests expérimentaux ont montré un comportement fortement non-linéaire de la structure. Nous avons obtenu une conversion d'énergie mécanique en énergie électrique correspondant à une puissance maximale de 2.3 μW à 260 Hz, pour une accélération de 1 g et à une pression de 0.15 Torr, lorsque le système est pré-chargé avec une tension de 10 V. Une fois implémenté dans un circuit de pompe de charge et pour les mêmes conditions d'accélération et de pression, le système peut fonctionner en complète autonomie pendant plus de 500 secondes pendant lesquelles la puissance délivrée varie de 1.4 μW à 940 nW avec une tension de pré-charge de 10.6 V<br>A relevant solution to power isolated sensors is to harvest the energy available in their immediate environment. Among the possible sources of energy, our choice was made on ambient mechanical vibrations. We have designed and fabricated a silicon-based and batch-processed MEMS electrostatic transducer which does not use an electret. We present an analytical method to optimize the efficiency of the electrostatic generator, while a voltage limitation on the transducer's terminal is set to prevent any damage in the conditioning electronics. The proposed design also takes into account some possible variations in the amplitude of external vibration. The device was fabricated in ESIEE Paris and its volume is less than 100 mm3. The device was tested experimentally and exhibits a strong non-linear behavior. We obtained a conversion of mechanical energy into electrical energy corresponding to a power of 2.3 μW at 260 Hz, with an acceleration of 1 g and a pressure of 0.15 Torr, when the system is pre-charged with a voltage of10 V. When the device is implemented in a charge pump circuit and under the same parameters of acceleration and pressure, the system can operate in autonomous mode for more than 500 seconds during which the output power varies from 1.4 μW to 940 nW when the pre-charge voltage is 10.6 V
46
Boisseau, Sébastien. "Récupération d'énergie vibratoire à électrets." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00644697.
Full textAbstract:
Issus de l'industrie de la microélectronique, les MEMS (Micro Electro Mechanical Systems) envahissent progressivement le marché avec des applications dans de nombreux domaines tels que l'aérospatiale, la médecine, l'industrie ou encore le grand public. Une des vocations de ces microstructures est de permettre le déploiement de réseaux de capteurs autonomes, c'est-à-dire d'un ensemble de systèmes capables de collecter des informations de leur environnement, de les traiter, de les transmettre et d'interagir entre eux, et ceci, sans intervention humaine. Comment rendre ces microsystèmes énergétiquement autonomes ? Utiliser des piles... Malheureusement, le défaut majeur des piles est leur durée de vie, puisqu'il faudra à un moment ou à un autre les recharger ou les remplacer. En fait, avec la miniaturisation, les systèmes deviennent de moins en moins consommateurs d'énergie et ceci permet de concevoir de nouvelles sources d'énergie basées sur la récupération de l'énergie ambiante (soleil, gradients de température,...). Il est par exemple possible de récupérer l'énergie des vibrations ambiantes à l'aide de systèmes piézoélectriques, électromagnétiques ou encore électrostatiques. Dans ce travail de thèse, nous nous concentrons sur l'étude de structures électrostatiques utilisant les électrets (diélectriques chargés électriquement). De l'étude des électrets à la réalisation et à l'optimisation de structures de récupération d'énergie, nous exposons dans ce mémoire, les résultats obtenus au cours de ce travail de thèse.
47
TERRA, FEDERICA. "Simulazione della propagazione del pacchetto di elettroni in una streak-camera ultra veloce." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/883.
Full textAbstract:
Il lavoro contenuto in questa tesi è volto a fornire le linee guida per la progettazione di una streak camera. Tramite simulazioni, sviluppate con il programma Simion 3-D, è stato possibile determinare quali parametri influenzino maggiormente le performance di questo strumento e, poiché lâ evoluzione del pacchetto di elettroni allâ interno del canale di una streak camera è influenzata da vari e molteplici fattori, le simulazioni sono organizzate per ottenere lâ andamento delle dimensioni e delle caratteristiche del fascio in funzione di ciascuno di questi parametri ed in ognuna delle regioni del canale.
Eâ stata simulata la propagazione degli elettroni sotto lâ effetto dellâ accelerazione della griglia e poi sotto lâ effetto focalizzante delle lenti elettrostatiche, prendendo in considerazione gli effetti della carica spaziale, della distribuzione di energia, angolare e temporale dei foto-elettroni e le caratteristiche geometriche e costruttive del sistema fotocatodo-griglia e del sistema di focheggiamento.
Ciascun passaggio dellâ impulso luminoso, prima, e dei foto-elettroni, dopo, è stato analizzato e studiato a fondo per arrivare allâ elaborazione di un prototipo di streak camera per il progetto FASTEST-CAM. Questo rivelatore sarà capace di misurare lâ andamento dellâ intensità , verso il tempo oppure verso lo spazio, di fenomeni ultraveloci con una risoluzione temporale che si suppone possa essere di 200fs.
Tra le possibili applicazioni di questa streak camera, ci sarà lo studio della radiazione proveniente dallâ interazione dei progetti PLASMONX (PLasma Acceleration at Sparc and MONochromatic X-ray generation project) e SPARC (Sorgente Pulsata Auto-amplificata di Radiazione Coerente): impulsi laser e pacchetti di elettroni di alta brillanza, sincronizzati fra loro, potranno interagire consentendo di realizzare esperimenti di accelerazione a plasma e sorgenti X-gamma basate sullo scattering Thomson.<br>This research study aims at providing the guidelines to design a streak camera. Through simulations, developed with the software Simion 3-D, the parameters that most influence this tool were determined. Furthermore, since the evolution of the electron bunch inside a streak camera is influenced by numerous factors, the simulations were organized in order to obtain the trend of the dimensions and characteristics of the bunch according to the function of each parameter and in each part of such tool.
The propagation of photo-electrons under the effect of the extraction mesh and later under the focusing electrostatic lens effect was simulated taking into consideration the effects of space-charge, of energy, angular and temporal initial distributions of photo-electrons and the geometrical and constructive characteristics of the photocathode-to-mesh and lens focusing systems.
Each passage of light pulse, first, and of photo-electrons, later, was analyzed and carefully investigated in order to elaborate a streak camera prototype for the FASTEST-CAM project. Such detector shall be able to measure the intensity versus time or space, of ultrafast phenomena with a temporal resolution that presumably amounts to 200fs.
Among the various uses of this streak camera, there will be the analysis of the radiation coming from the interaction of PLASMONX (PLasma Acceleration at Sparc and MONochromatic X-ray generation project) and SPARC (Sorgente Pulsata Auto-amplificata di Radiazione Coerente) projects: synchronised ultraintense laser pulses and high-quality electron bunches, might interact thus giving the opportunity to explore Thomson scattering physics and applications.
48
Xin, W. (Weidong). "Continuum electrostatics of biomolecular systems." Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514287602.
Full textAbstract:
Abstract
Electrostatic interactions are very important in biomolecular systems. Electrostatic forces have received a great deal of attention due to their long-range nature and the trade-off between desolvation and interaction effects. It remains a challenging task to study and to predict the effects of electrostatic interactions in biomolecular systems. Computer simulation techniques that account for such interactions are an important tool for the study of biomolecular electrostatics.
This study is largely concerned with the role of electrostatic interactions in biomolecular systems and with developing novel models to estimate the strength of such interactions.
First, a novel formulation based upon continuum electrostatics to compute the electrostatic potential in and around two biomolecules in a solvent with ionic strength is presented. Many, if not all, current methods rely on the (non)linear Poisson-Boltzmann equation to include ionic strength. The present formulation, however, describes ionic strength through the inclusion of explicit ions, which considerably extends its applicability and validity range. The method relies on the boundary element method (BEM) and results in two very similar coupled integral equations valid on the dielectric boundaries of two molecules, respectively. This method can be employed to estimate the total electrostatic energy of two protein molecules at a given distance and orientation in an electrolyte solution with zero to moderately high ionic strength.
Secondly, to be able to study interactions between biomolecules and membranes, an alternative model partly based upon the analytical continuum electrostatics (ACE) method has been also formulated. It is desirable to develop a method for calculating the total solvation free energy that includes both electrostatic and non-polar energies. The difference between this model and other continuum methods is that instead of determining the electrostatic potential, the total electrostatic energy of the system is calculated by integrating the energy density of the electrostatic field. This novel approach is employed for the calculation of the total solvation free energy of a system consisting of two solutes, one of which could be an infinite slab representing a membrane surface.
49
Svärd, Michael. "Structural, Kinetic and Thermodynamic Aspects of the Crystal Polymorphism of Substituted Monocyclic Aromatic Compounds." Doctoral thesis, KTH, Teknisk strömningslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33836.
Full textAbstract:
This work concerns the interrelationship between thermodynamic, kinetic and structural aspects of crystal polymorphism. It is both experimental and theoretical, and limited with respect to compounds to substituted monocyclic aromatics. Two polymorphs of the compound m-aminobenzoic acid have been experimentally isolated and characterized by ATR-FTIR spectroscopy, X-ray powder diffraction and optical microscopy. In addition, two polymorphs of the compound m-hydroxybenzoic acid have been isolated and characterized by ATR-FTIR spectroscopy, high-temperature XRPD, confocal Raman, hot-stage and scanning electron microscopy. For all polymorphs, melting properties and specific heat capacity have been determined calorimetrically, and the solubility in several pure solvents measured at different temperatures with a gravimetric method. The solid-state activity (ideal solubility), and the free energy, enthalpy and entropy of fusion have been determined as functions of temperature for all solid phases through a thermodynamic analysis of multiple experimental data. It is shown that m-aminobenzoic acid is an enantiotropic system, with a stability transition point determined to be located at approximately 156°C, and that the difference in free energy at room temperature between the polymorphs is considerable. It is further shown that m-hydroxybenzoic acid is a monotropic system, with minor differences in free energy, enthalpy and entropy. 1393 primary nucleation experiments have been carried out for both compounds in different series of repeatability experiments, differing with respect to solvent, cooling rate, saturation temperature and solution preparation and pre-treatment. It is found that in the vast majority of experiments, either the stable or the metastable polymorph is obtained in the pure form, and only for a few evaluated experimental conditions does one polymorph crystallize in all experiments. The fact that the polymorphic outcome of a crystallization is the result of the interplay between relative thermodynamic stability and nucleation kinetics, and that it is vital to perform multiple experiments under identical conditions when studying nucleation of polymorphic compounds, is strongly emphasized by the results of this work. The main experimental variable which in this work has been found to affect which polymorph will preferentially crystallize is the solvent. For m-aminobenzoic acid, it is shown how a significantly metastable polymorph can be obtained by choosing a solvent in which nucleation of the stable form is sufficiently obstructed. For m-hydroxybenzoic acid, nucleation of the stable polymorph is promoted in solvents where the solubility is high. It is shown how this partly can be rationalized by analysing solubility data with respect to temperature dependence. By crystallizing solutions differing only with respect to pre-treatment and which polymorph was dissolved, it is found that the immediate thermal and structural history of a solution can have a significant effect on nucleation, affecting the predisposition for overall nucleation as well as which polymorph will preferentially crystallize. A set of polymorphic crystal structures has been compiled from the Cambridge Structural Database. It is found that statistically, about 50% crystallize in the crystallographic space group P21/c. Furthermore, it is found that crystal structures of polymorphs tend to differ significantly with respect to either hydrogen bond network or molecular conformation. Molecular mechanics based Monte Carlo simulated annealing has been used to sample different potential crystal structures corresponding to minima in potential energy with respect to structural degrees of freedom, restricted to one space group, for each of the polymorphic compounds. It is found that all simulations result in very large numbers of predicted structures. About 15% of the predicted structures have excess relative lattice energies of <=10% compared to the most stable predicted structure; a limit verified to reflect maximum lattice energy differences between experimentally observed polymorphs of similar compounds. The number of predicted structures is found to correlate to molecular weight and to the number of rotatable covalent bonds. A close study of two compounds has shown that predicted structures tend to belong to different groups defined by unique hydrogen bond networks, located in well-defined regions in energy/packing space according to the close-packing principle. It is hypothesized that kinetic effects in combination with this structural segregation might affect the number of potential structures that can be realized experimentally. The experimentally determined crystal structures of several compounds have been geometry-optimized (relaxed) to the nearest potential energy minimum using ten different combinations of common potential energy functions (force fields) and techniques for assigning nucleus-centred point charges used in the electrostatic description of the energy. Changes in structural coordinates upon relaxation have been quantified, crystal lattice energies calculated and compared with experimentally determined enthalpies of sublimation, and the energy difference before and after relaxation computed and analysed. It is found that certain combinations of force fields and charge assignment techniques work reasonably well for modelling crystal structures of small aromatics, provided that proper attention is paid to electrostatic description and to how the force field was parameterized. A comparison of energy differences for randomly packed as well as experimentally determined crystal structures before and after relaxation suggests that the potential energy function for the solid state of a small organic molecule is highly undulating with many deep, narrow and steep minima.<br>QC 20110527
50
Vuković, Vedran. "Calculs électrostatiques rapides dans l'analyse énergétique : Développement de la méthode, applications aux études de cristaux organiques et organométalliques et de complexes protéine/ligand." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0163.
Full textAbstract:
La nature électrostatique des atomes est généralement prise en compte pour explorer les interactions intermoléculaires. Le modèle multipolaire de Hansen-Coppens est largement utilisé pour obtenir une description détaillée de la distribution des électrons. Il s'agit donc d'un point de départ pour étudier le comportement de systèmes chimiques. Le choix du système donne accès à des informations microscopiques qui permettent d'élucider les propriétés des matériaux à l'échelle macroscopique. L'une de ces propriétés est l'énergie d'interaction électrostatique, qui indique la force avec laquelle deux charges s'attirent ou se repoussent. Le modèle multipolaire donne une image claire de la distribution des charges à l'intérieur des molécules. Les énergies obtenues à partir de ce modèle sont plus fiables que celles provenant de méthodes traditionnelles (comme les charges ponctuelles). Des méthodes existent déjà pour calculer l'énergie d'interaction électrostatique à partir du modèle multipolaire, mais leur point faible est qu'elles prennent du temps pour calculer les intégrales sous-jacentes. La méthode discutée dans cette thèse (potentiel analytique exact / moments pseudo-multipolaires, aEP/pMM) propose une intégration analytique rapide à la place de l'intégration numérique de l'ancienne méthode. Cette nouvelle méthode a été intégrée dans le programme Charger. Le gain de vitesse provient du remplacement d'une cubature 3D par une intégrale unidimensionnelle, grâce aux propriétés mathématiques du modèle multipolaire. Ce gain varie d'un facteur 4 à 200, et les énergies résultantes sont presque indiscernables de celles obtenues par l'ancienne méthode. L'objectif était également d'estimer le potentiel de Charger en termes d'application. Il a été testé sur des complexes protéine-ligand, des molécules organiques et des complexes métal-organique impliquant de nombreux éléments des trois premières rangées du tableau périodique. Un complexe organométallique contenant des atomes de nickel dans son cœur a également été analysé. Dans toutes ces applications, Charger domine sur l'ancienne approche en termes de temps de calcul, tout en conservant une précision exceptionnelle. L'analyse du complexe protéine/ligand a permis de distinguer les environnements favorables et défavorables à la fixation du ligand. Elle a également révélé un candidat possible à la mutation qui confère un pouvoir prédictif à l'approche Charger. Le complexe métal-organique contenait un contact particulier que Charger a aidé dans sa caractérisation. Il a également permis le calcul de l'énergie électrostatique de la maille cristalline pour un composé organique et un composé organométallique. L'auteur espère que la nouvelle approche aEP/pMM recevra un accueil positif et contribuera à de nombreuses découvertes dans divers domaines qui reposent sur la modélisation moléculaire<br>One usually considers the electrostatic nature of atoms to explore intermolecular interactions. The Hansen-Coppens multipolar model is widely used to bring a detailed view of electron distribution on an atomic scale. It is thus a common starting point to investigate chemical behaviour of selected systems, giving access to microscopic insights that elucidate material properties on the large scale.One such property is the electrostatic interaction energy, which tells how strongly two charges attract or repel each other. The multipolar model brings forward a clear picture of charge distributions inside molecules, so a calculation of electrostatic energy based on it provides a better estimate than by using traditional methods (simplifications like point charges). The methods already exist to calculate electrostatic interaction energy, but their weak point is that they take their time to calculate the underlying integrals.The method discussed in this thesis (analytical exact potential / pseudo-multipolar moments, aEP/pMM) replaces the slow numerical integration inherent to the older method with analytical integration. It was integrated in the program Charger. The boost of speed comes from replacing a 3D cubature with a one-dimensional integral, due to favourable mathematical properties of the underlying multipolar model. The improvement in speed goes from 4 to 200 times, and the resulting energies are almost indistinguishable from those obtained by the older method.The goal was also to see how wide one can cast the net of this new Charger approach. It was tested on protein/ligand complexes, organic molecules and metal-organic complexes involving many elements of the first three rows in the periodic table. It was also applied on an organometallic complex containing nickel atoms in its core. In all of these applications, Charger reigned supreme over the old approach in terms of computational time, while guarding exceptional accuracy.The application on the protein/ligand complex pointed to residues which are the major contributors and detractors to ligand binding. It also revealed a possible mutation candidate that could show the predictive power of the Charger approach. The metal-organic complex contained a peculiar contact: Charger helped to characterise it. Charger also unveiled the electrostatic energy of crystal packing for an organic and an organometallic compound. The author hopes that the new aEP/pMM approach will encounter a positive reception and contribute to many an interesting finding across various fields that rely on molecular modeling