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Shi, Wen Juan. "Dynamic frequency compensation for transducers." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316439.
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Jafaripanah, Mehdi. "Analogue adaptive techniques for dynamic sensor frequency compensation." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419164.
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Pérez, Alepuz Javier. "Dynamic visual servoing of robot manipulators: optimal framework with dynamic perceptibility and chaos compensation." Doctoral thesis, Universidad de Alicante, 2017. http://hdl.handle.net/10045/72433.
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This Thesis presents an optimal framework with dynamic perceptibility and chaos compensation for the control of robot manipulators. The fundamental objective of this framework is to obtain a variety of control laws for implementing dynamic visual servoing systems. In addition, this Thesis presents different contributions like the concept of dynamic perceptibility that is used to avoid image and robot singularities, the framework itself, that implements a delayed feedback controller for chaos compensation, and the extension of the framework for space robotic systems. Most of the image-based visual servoing systems implemented to date are indirect visual controllers in which the control action is joint or end-effector velocities to be applied to the robot in order to achieve a given desired location with respect to an observed object. The direct control of the motors for each joint of the robot is performed by the internal controller of the robot, which translates these velocities into joint torques. This Thesis mainly addresses the direct image-based visual servoing systems for trajectory tracking. In this case, in order to follow a given trajectory previously specified in the image space, the control action is defined as a vector of joint torques. The framework detailed in the Thesis allows for obtaining different kind of control laws for direct image-based visual servoing systems. It also integrates the dynamic perceptibility concept into the framework for avoiding image and robot singularities. Furthermore, a delayed feedback controller is also integrated so the chaotic behavior of redundant systems is compensated and thus, obtaining a smoother and efficient movement of the system. As an extension of the framework, the dynamics of free-based space systems is considered when determining the control laws, being able to determine trajectories for systems that do not have the base attached to anything. All these different steps are described throughout the Thesis. This Thesis describes in detail all the calculations for developing the visual servoing framework and the integration of the described optimization techniques. Simulation and experimental results are shown for each step, developing the controllers in an FPGA for further optimization, since this architecture allows to reduce latency and can be easily adapted for controlling of any joint robot by simply modifying certain modules that are hardware dependents. This architecture is modular and can be adapted to possible changes that may occur as a consequence of the incorporation or modification of a control driver, or even changes in the configuration of the data acquisition system or its control. This implementation, however, is not a contribution of this Thesis, but is necessary to briefly describe the architecture to understand the framework’s potential. These are the main objectives of the Thesis, and two robots where used for experimental results. A commercial industrial seven-degrees-of-freedom robot: Mitsubishi PA10, and another three-degrees-of-freedom robot. This last one’s design and implementation has been developed in the research group where the Thesis is written.
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Shivaprasad, Mala A. "Dynamic Dealy Compensation and Synchronisation Services for Continuous Media Streams." Thesis, Indian Institute of Science, 1995. http://hdl.handle.net/2005/144.
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Multimedia' nature of an application refers to the presence of several media streams in parallel. Whether it is receiving real-time data or retrieving stored data, there exists an end-to-end delay in data transfer from source to destination over the network. This delay experienced can be split into a fixed part and a variable part. Data processing time like coding and decoding at the source and destination are the fixed delays experienced. The variable delay occurs mainly due to queuing at the intermediate nodes during its flow through the network. The variable or unequal delays introduce gaps or discontinuities within a stream. In multi-stream applications where each stream may flow on different routes based on the bandwidth availability experiencing different delays, mismatch between them can also occur. These discontinuities and skews result in poor quality of playout. Clock drift and variations in drift rates between the source/s and destination/s, clock also lead to poor quality of play out. To eliminate these skews and discontinuities, there must be mechanisms, viz., and synchronisation services to convey, reintroduce and maintain the temporal relationship between the media streams for presentation throughout the playout, at the destination. The reintroduction of this lost temporal relationship within a stream and between various media streams for presentation at the destination is the object of multimedia synchronisation and is the subject matter of this thesis.
In the presence of synchronised clocks, the main cause of asynchronies between media streams is the difference in delays experienced and the jitter. In this work, to convey the temporal relationship between streams of an application to the playout site, each stream is assigned a priority л, based on its importance to the user. The media streams are then divided into synchronisation units called 'Groups' based on that stream's characteristics which has the highest priority л. A group may therefore consist of one video frame and other data which were generated in that interval. Or may consist of silence and talk-spurt periods of the voice stream with data units of other streams generated in the same interval.
Since the quality of playout of temporally related delay-sensitive streams depends upon the delay-experienced, the concept of QoS can be extended to describe the presentation requirements of uch data. Depending on the user perception and the delay experienced, an application can have a range of playout times, giving the best performance. The presentation of many real-time applications can be considered satisfactory even when the delay bound is exceeded by a small amount for a short period of time under varying network conditions. This property can be exploited by defining two sets of QoS parameters, namely QoS optimum and QoSlimit for each real-time application. As the delay and its variations increase, the optimum playout time range
decreases. QoS optimum specifies the performance parameters required to perceive 'realtime'. Multimedia data can be played out at its QoSlimit with a deterioration in quality under poor network conditions still maintaining the synchronisation between streams. To control the playout at two levels of QoS, and maintain intra-media and inter-media synchronisation, stream controllers and super stream controllers have been used.
The dynamic delay compensation algorithm and synchronisation services were simulated using network delay models and performances studied. It is shown that the proposed algorithm not only synchronised media streams and smoothened jitter but also optimised buffer space and buffer occupancy time while meeting the desired quality of service requirements
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Prasai, Anish. "Direct dynamic control of impedance for VAR and harmonic compensation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42816.
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Reactive power is critical to reliable operation of the modern AC power system. There is a plethora of motor-loads, transformers, and power-electronic loads connected to the power grid, which consume reactive power for normal operation. Transmission lines also consume reactive power when they are loaded above their surge impedance loading (SIL). Reactive power can exact opportunity cost due to reduced capacity of the lines to carry real power, which in turn lowers revenue. Most transmission owners (TOs) levy large penalties against load serving entities (LSEs), industrial facilities, and other end-use customers, who consume more than their allotted amount, as measured by their power factor. These penalties are to incentivize their customers to meet their reactive power needs locally as well as to recuperate the TOs' financial losses.
Harmonic pollution is another factor that prevents the optimal operation of the grid and the connected loads. Harmonics are attributable to proliferation of the diode-rectifier- or thyristor-rectifier-interfaced loads such as variable speed ac drives and power supplies in server farms, electric arc furnaces, and other non-linear loads, which are widely employed by the industrial sector. With wider adoption of harmonic-rich loads by the consumer sector as well, such as HDTVs and compact fluorescent lamps (CFLs), greater level of triplen harmonics associated with single-phase loads are also increasingly seen on the distribution grid. The increasing penetration of renewable resources and electrification of light-duty vehicles are expected to further aggravate the stresses and congestion on the utility grid.
Reactive power compensation is necessary for supporting the AC grid and maintaining a healthy voltage stability margin. Compensation can also enhance the utilization of system capacity, lower system losses, provide fault ride-through, and enable a quick fault recovery. Existing VAR and harmonic compensation technologies are either too expensive or inadequate to meet the dynamic needs of the modern and the future power system.
This dissertation presents a novel class of Dynamic VAR and Harmonic Compensators (DVHCs) for supplying or absorbing reactive power and providing harmonic filtering, where the compensation is in shunt with the line and the load. The underlying concept is based on augmenting a static or passive component like a capacitor or an inductor with a direct AC converter and imbuing the passive component with dynamic properties. The direct AC converter can be configured as a buck, a boost, or a buck-boost. A `fail-normal' switch is an integral part of the DVHCs that bypasses the converter when it fails, preserving the original functionality and the reliability of the passive component. The DVHCs are modular and scalable such that they can be employed in applications ranging from residential and industrial with voltages less than 480 V, to power distribution level with voltages as high as 35 kV. The Dynamic Inductor (D-IND) and the Dynamic Capacitor (D-CAP) are subclasses of the DVHCs. As the applications for supplying leading VARs are more prevalent, the primary focus of this work is on the buck, the boost, and the buck-boost configurations of the D-CAP.
To understand the characteristics and operation of the DVHCs, this work has developed time-domain models for analyzing the transient and dynamic behavior; frequency-domain models for understanding the harmonic interactions and the steady-state relationships between switch duty and current harmonics; and small-signal models for studying the dynamics of the converter due to various perturbations. The small-signal models also enable extraction of transfer functions in designing controllers and assessing stability margins.
Control architectures and techniques are presented for effectively controlling the D-CAP when commutating the semiconductor devices with both high and low switching frequencies.
In modularly scaling the DVHCs to higher voltages, three medium-voltage topologies are discussed. They are based on series-connecting fractionally-rated devices, AC flying capacitors, and series cascading multiple two-level cells. These implementations allow direct connect to the medium-voltage grid, thereby obviating the use of transformers, and subsequently reducing the losses, cost, complexity, and footprint. A novel AC snubber concept is proposed to provide safe commutation of the AC switches, fault tolerance by managing the energy trapped in parasitics and filters, and to enable dynamic and static voltage sharing when integrated around the series-connected devices.
Design equations for selecting and rating the devices and components in the buck, the boost, and the buck-boost configurations of the D-CAP are presented. Three sets of example designs, with one at low-voltage and two at medium-voltage, are discussed to demonstrate the typical size and ratings of the various components under realistic operating conditions.
Measurements and the related discussions of a 40 kVA buck D-CAP prototype built to validate the effectiveness of the proposed concepts are presented.
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Lau, Wai Keung. "Current-mode DC-DC buck converter with dynamic zero compensation /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?ECED%202006%20LAU.
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Balatsos, Aris. "Clock buffer IC with dynamic impedance matching and skew compensation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0012/MQ34127.pdf.
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Beasley, Andrew Stephen. "Digital compensation of the dynamic transfer characteristics of RF amplifiers." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/37939.
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Radermacher, Tobias, Jan Lübbert, and Jürgen Weber. "On the Compensation of Dynamic Reaction Forces in Stationary Machinery." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200212.
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This paper studies a method for active electrohydraulic force compensation in industrial scale high power applications. A valve controlled cylinder moves a mass using the force of inertia to compensate for the reaction forces of an industrial process. Two strategies for force compensation are developed and investigated in a 160 ton clamping unit of an injection moulding machine to significantly reduce the excitation. Results of the different strategies are shown and evaluated. Advantages and drawbacks of the developed electrohydraulic force compensation are discussed.
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Patil, Krishnat V. "Dynamic compensation of electrical power systems using a new BVSI STATCOM." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0008/NQ40284.pdf.
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Walters, Wesley F. "Dynamic analysis of the Low Power Atmospheric Compensation Experiment (LACE) spacecraft." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241361.
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Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, June 1990.Thesis Advisor(s): Kolar, Ramesh. "June 1990." Description based on title screen as viewed on October 15, 2009. DTIC Identifier(s): Flight Dynamics, Thermoelastic Effects, Chaotic Vibrations, Lace(Low Power Atmospheric Compensation Experiment). Author(s) subject terms: Dynamic Analysis, Thermoelastic Effects, Chaotic Vibrations. Includes bibliographical references (p. 205-207). Also available in print.
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Bokaris, Panagiotis-Alexandros. "Video-projected augmented reality : Photometric compensation for static and dynamic concealment." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS453/document.
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Cette thèse développe de nouvelles approches pour l'effacement et la révélation de la présence humaine en utilisant des techniques de réalité augmentée. Elle se concentre sur les systèmes projecteur-caméra (ProCams) et leur application dans les «projections intelligentes», où le contenu virtuel projeté est adapté en fonction de l'environnement. Nous nous appuyons sur les travaux antérieurs sur la compensation photométrique pour projeter sur une surface colorée fixe qui permet au spectateur d'observer la même image telle qu'elle apparaîtrait sur une surface blanche. Malgré les différentes méthodes de compensation des couleurs qui ont été proposées au cours de décennie, la compensation appliquée à monde réel avec des couleurs saturées et vives est encore une question ouverte. L'objectif principal de ce travail est la compensation photométrique sur un objet 3D en mouvement en utilisant un ProCam, ce qui est un scénario considérablement plus difficile. Une nouvelle méthode pour la compensation de couleur à l'aide d'une image d'entrée unique est proposée. Elle consiste à estimer la réflectance spectrale de la surface afin de compenser celle-ci en supposant que les réponses du projecteur sont connues ou mesurées précédemment. Cette méthode a été entièrement développée sur GPU pour permettre une compensation en temps réel. Les méthodes antérieures sur la compensation couleur sont discutées et comparées afin d'évaluer la performance de notre technique. L'étalonnage photométrique et géométrique précis d'un ProCam est essentiel pour une compensation précise. Une nouvelle technique de calibration géométrique entre un capteur de profondeur et un ProCam est présentée dans le but de réaliser la projection sur un objet en mouvement. Une calibration photométrique est décrite pour la transformation des valeurs RGB de la caméra et du projecteur (dépendantes du périphérique) vers l'espace couleur CIE XYZ 1931 (indépendantes du périphérique). Le potentiel artistique des techniques de réalité augmentée proposées est en outre exploré à travers l'installation interactive artistique “Gardien du Temple”. La révélation et l'effacement ont toujours été un terrain d'expérimentation commun aux artistes et aux scientifiques. Cette installation audiovisuelle utilise la réalité augmentée pour effacer la présence d'un poème écrit sur un tapis invitant le spectateur à le révéler. Dans de telles applications, la précision et la robustesse des méthodes utilisées sont cruciales. Cette installation artistique a donc permis de tester et d'évaluer les travaux de cette thèse dans un contexte collaboratif et exigeantThis thesis develops new approaches for human presence concealment and revelation using augmented reality techniques. It focuses on projector-camera systems (ProCams) and their application in “smart projections”, where the projected virtual content is adapted according to the environment. One previously-studied problem is the photometric compensation for projecting on a colored fixed surface that allows the viewer to observe the same image as it would appear on a white surface. Despite the various methods for color compensation that have been proposed the last decade, compensation on a real-world surface with saturated colors and sharp color boundaries is still an open issue. The main objective of this work is the color compensation on a moving 3D object using a ProCam, which is a dramatically more challenging scenario. A novel method for color compensation using a single input frame is proposed. It consists in estimating the spectral reflectance of the surface in order to compensate for it under the assumption that the projector responses are known or previously measured. This method was fully developed on GPU to enable real-time compensation. Previous methods on color compensation are discussed and compared in order to evaluate the performance of our technique. The accurate photometric and geometric calibration of a ProCam is essential for precise compensation. A new geometric calibration technique between a depth sensor and a ProCam is presented in order to make the projection on a moving object feasible. A photometric calibration is described for the transformation of the device-dependent camera and projector values to the device-independent CIE XYZ 1931 color space. The artistic potential of the proposed augmented reality techniques is further explored through the interactive art installation “Gardien du Temple”. Revelation and concealment has always been a common experimentation ground for both artists and scientists. This audio visual installation uses augmented reality to hide the presence of a written poem on a carpet inviting the spectator to reveal it. In such applications, the accuracy and robust performance of the methods employed is crucial and, thus, it offered a challenging ground for testing and evaluation
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Acarman, Tankut. "Frequency shaping and other dynamic compensation methods for sliding mode control /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486463321624227.
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Swanepoel, Pieter Frederick Renier. "Dynamic compensation for performance characteristic differences of wind generator coupled pumps." Thesis, Port Elizabeth Technikon, 2000. http://hdl.handle.net/10948/25.
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The lack of services such as electricity in the rural areas of South Africa has given rise to the use of pump water and the windmills. The ones in use currently are maintenance intensive. There is a corrosive element in water and this sometimes requires plastic or other non-corrosive materials to be used for pump components and pipes. Solar panels are expensive and have low efficiencies. Alternative energy systems such as diesel engine driven- mono pumps or -turbines or windmills are costly, which means that the overall efficiency must be maximized to reduce these costs.
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Guney, Metin G. "High Dynamic Range CMOS-MEMS Capacitive Accelerometer Array with Drift Compensation." Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1155.
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This thesis explains the design, fabrication and characterization steps of a high dynamic range CMOS-MEMS capacitive accelerometer array and on-chip environmental sensors for bias drift compensation. Inertial navigation under harsh environments requires a high dynamic range accelerometer that can survive and provide continuous readout accuracy through shock events, while having a large dynamic range to capture fine-scale motions. The dynamic range target is set as 156 dB in accordance with navigation standard macro-electromechanical accelerometers, which corresponds to around 1 mG acceleration resolution in 50 kG input range. The small accelerometer cell design ensures shock survivability (e.g. up to 50 kG) by keeping the stress at the anchors below the fracture strength of thin-film oxide. Arraying multiple accelerometer cells in parallel lowers the fundamental thermomechanical noise limit set by the small mass of the individual accelerometer cells. Resonance frequency staggering between accelerometer cells suppresses ring-down oscillations. Parasitic capacitance of the high-impedance transduction signal is important to mitigate; undercut of the underlying silicon substrate and an aluminum etch of the top metal layer, incorporated in the CMOS-MEMS process flow, reduces the parasitic capacitance and improves sensitivity. PTAT temperature sensors, piezoresistive stress sensors and resonator-oscillators integrated across the accelerometer chip provide high-resolution environmental measurements for the compensation of long-term bias and scale factor drift. Simultaneous measurements from the accelerometer and environmental sensors demonstrate the correlation between environmental variations and long-term drift. Finite-element analysis shows that the scale factor stability of the accelerometer can be improved up to 1 ppm given the sensor array’s measurement resolution. The CMOS-MEMS accelerometer system-on-chip is fabricated in a TowerJazz 0.18 μm CMOS process. The post-CMOS MEMS processing steps are tuned to reduce the top metal milling and sidewall polymer deposition. A reactive ion etch recipe is developed for the removal of the top metal in order to reduce the parasitic capacitance and eliminate the risk of metal creep at spring beam anchors, thereby improve the bias stability. The PTAT temperature sensors have 3.1 mV/K measured sensitivity and 7.1 mK resolution with high repeatability. The compensation of the accelerometer readout for temperature variations down to 7.1 mK translates to 2.6 ppm scale factor stability for the accelerometer. The characterization of the stress sensors through the application of normal stress on the device package leads to an uncertainty in the amount of stress transferred to the stress sensors on the chip surface. The maximum measured stress sensitivity is 36.5 pV/Pa, which leads to 24.7 kPa stress resolution and translates to 1.7 ppm scale factor stability for the accelerometer without taking the stress attenuation into account. The measured sensitivity sets a lower bound on the sensitivity of the stress sensors implying that the stress resolution and the corresponding accelerometer scale factor stability is higher in practice. The measured frequency stability of the resonator-oscillator is 0.4 ppm, thereby the resonance frequency based variations of the accelerometer readout can be compensated to reach up to 0.8 ppm scale factor stability. However, the initial drift in the resonance frequency of the oscillators due to dielectric charging requires a long wait-time before these sensors can be used for accelerometer drift compensation. The accelerometer array is demonstrated to have 23.7 mG/√Hz noise floor and 70 mG bias stability. The maximum input acceleration applied on the device is limited to 4 kG by the split Hopkinson bar test setup. Improvement of the setup to transfer acceleration amplitudes up to 50 kG should validate the designed input range of the accelerometer array and lead to 117 dB dynamic range for the current design. The measurement bandwidth is fundamentally set by the 126 kHz resonance frequency of the accelerometer cells and can be further limited by filtering the readout signal to attenuate the transient oscillations faster. The nonlinearity of the accelerometer response is better than 1.2% in ±10 kG input range; however, it gets up to 19.0% in ±50 kG maximum input range. The long term bias drift of the accelerometer is shown to be correlated with the temperature and stress variations. Compensation of the accelerometer readout based on the stress and temperature sensor measurements leads to an observable improvement in the long term drift. However, the bias stability of the accelerometer is limited by excessive flicker noise in the system, which is believed to result from noise folding from higher frequencies. Suppression of the flicker noise in the system should allow for a more detailed study of the effect of environmental variations on the accelerometer readout and evaluation of more elaborate fitting algorithms for model based prediction and compensation of the bias drift to reach the target bias stability and dynamic range.
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Shan, Yaping. "Essays on dynamic contracts." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3534.
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This dissertation analyzes the contracting problem between a firm and the research employees in its R&D department. The dissertation consists of two chapters. The first chapter addresses a simplified problem in which the R&D unit has only one agent. The second chapter studies a scenario in which the R&D unit consists of a team.
In the first chapter, I look at problem in which a principal hires an agent to do a multi-stage R&D project. The transition from one stage to the next is modeled by a Poisson-type process, whose arrival rate depends on the agents choice of effort. I assume that effort choice is binary and unobservable by the principal. To overcome the repeated moral-hazard problem, the principal offers the agent a long-term contract which specifies a flow of payments based on his observation of the outcome of the project. The optimal contract combines rewards and punishments: the payment to the agent decrease over time in case of failure and jumps up to a higher level after each success. I also show that the optimal contract can be implemented by using a risky security that has some of the features of the stocks of these firms, thereby providing a theoretical justification for the wide-spread use of stock-based compensation in firms that rely on R&D.
In the second chapter, I look at a scenario in which the R&D unit consists of a team, which I assume, for simplicity, comprises two risk-averse agents. Now, the Poisson arrival rate is jointly determined by the actions of both agents with the action of each remaining unobservable by both the principal and the other agent. I assume that when success in a phase occurs the principal can identify the agent who was responsible for it. In this model, incentive compatibility means that each agent is willing to exert effort conditional on his coworker putting in effort, and thus exerting effort continuously is a Nash-equilibrium strategy played by the agents. In this multiagent problem, each agents payment depends not only on his own performance, but is affected by the other agents performance as well. Similar to the single-agent case, an agent is rewarded when he succeeds, and his payment decreases over time when both agents fail. Regarding how an agents payment relates to his coworkers performance, I find that the optimal incentive regime is a function of the way in which agents efforts interact with one another: relative-performance evaluation is used when their efforts are substitutes whereas joint-performance evaluation is used when their efforts are complements. This result sheds new light on the notion of optimal incentive regimes, an issue that has been widely discussed in multi-agent incentive problems.
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Stöppler, Guido [Verfasser]. "Active compensation of structural oscillations on high dynamic gantry machines / Guido Stöppler." Aachen : Shaker, 2005. http://d-nb.info/1186588349/34.
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Nikaeen, Parastoo. "Digital compensation of dynamic acquisition errors at the front-end of ADCs /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Chen, Zhuo. "Dynamic compensation and sensor fusion for a GSM-based water quality monitoring network." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58372.
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With the increasing demand for water, access to clean water is becoming a more challenging problem for people, in both rural and urban communities. The quantity and quality of fresh water resources, both surface water and ground water, are of major concern worldwide. A continuous water quality monitoring system with access to accurate real-time data can play an important role in water quality tracking and environmental protection. However, evaluation of water quality is complicated; on the one hand, a great number of physical, chemical and biological parameters are usually involved. Hence, multi-sensors network is often deployed for collecting a variety of useful water quality information, such as pH value, ammonia concentration, oxidation-reduction potential, temperature, electrical conductivity, turbidity, and the concentration of dissolved oxygen. On the other hand, objectives of in situ testing are complex and dynamic, and the testing environment in the field is also dynamic and harsh. This thesis develops a wireless data transmission platform to solve the communication problem between the monitoring sensor nodes in the field and the base station. What’s more, an individual sensor is only able to make a judgment using a single parameter as evidence. Simplex information is neither sufficient nor reliable, and some parameters also have mutual interference with each other to some extent. Specifically, there should be a systematic way to integrate information from multiple sensors to obtain more accurate and reliable water quality information. Furthermore, allowance has to be made for the variation in the conditions of a sensor, which will affect the sensor accuracy. Therefore, compensation and fusion of sensory data from disparate sources are very necessary to secure a reliable, accurate, and comprehensive monitoring result. By applying Dempster-Shafer theory and Euclidean Distance, this thesis presents a method of assigning four different parameters in the same scale, and combining them into an integrated and reliable quality evaluation result. The necessary methodologies are systematically presented. They are applied to realistic sensory data to illustrate their application and effectiveness.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Harvilla, Mark J. "Compensation for Nonlinear Distortion in Noise for Robust Speech Recognition." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/437.
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The performance, reliability, and ubiquity of automatic speech recognition systems has flourished in recent years due to steadily increasing computational power and technological innovations such as hidden Markov models, weighted finite-state transducers, and deep learning methods. One problem which plagues speech recognition systems, especially those that operate offline and have been trained on specific in-domain data, is the deleterious effect of noise on the accuracy of speech recognition. Historically, robust speech recognition research has focused on traditional noise types such as additive noise, linear filtering, and reverberation. This thesis describes the effects of nonlinear dynamic range compression on automatic speech recognition and develops a number of novel techniques for characterizing and counteracting it. Dynamic range compression is any function which reduces the dynamic range of an input signal. Dynamic range compression is a widely-used tool in audio engineering and is almost always a component of a practical telecommunications system. Despite its ubiquity, this thesis is the first work to comprehensively study and address the effect of dynamic range compression on speech recognition. More specifically, this thesis treats the problem of dynamic range compression in three ways: (1) blind amplitude normalization methods, which counteract dynamic range compression when its parameter values allow the function to be mathematically inverted, (2) blind amplitude reconstruction techniques, i.e., declipping, which attempt to reconstruct clipped segments of the speech signal that are lost through non-invertible dynamic range compression, and (3) matched-training techniques, which attempt to select the pre-trained acoustic model with the closest set of compression parameters. All three of these methods rely on robust estimation of the dynamic range compression distortion parameters. Novel algorithms for the blind prediction of these parameters are also introduced. The algorithms' quality is evaluated in terms of the degree to which they decrease speech recognition word error rate, as well as in terms of the degree to which they increase a given speech signal's signal-to-noise ratio. In all evaluations, the possibility of independent additive noise following the application of dynamic range compression is assumed.
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Plasencia, Oscar. "Modeling and Analysis of a Four-Switch Buck-Boost Dynamic Capacitor." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/660.
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Modern electric power utilities are facing a variety of challenges introduced by the increasing complexity of their operation, structure, and consumer loads. One such challenge has been to supply the ever growing demand for reactive power which is essential for grid support. For this reason dynamic VAR technologies are becoming much more important to modern day power systems. A recent dynamic VAR technology known as the Dynamic Capacitor offers full quadrant capacitive VAR control through the combination of AC/AC buck and boost cells. This paper introduces a new topology deemed the “Four-Switch Buck-Boost Dynamic Capacitor” which promises to combine the performance of the AC/AC buck and boost cells into a single power electronic device. This is done in an effort to reduce the required component count and thus reduce the overall device footprint and implementation cost of the Dynamic Capacitor technology. Derivations and analysis will detail the workings of the Four-Switch Buck-Boost Dynamic Capacitor, while simulations in LTSpice and Matlab Simulink will demonstrate the functionality and performance of the proposed topology. The results of this thesis prove the Four-Switch Buck-Boost Dynamic Capacitor to be a feasible shunt reactive compensating device.
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Silva, Andre Espozel Pinheiro da. "Testing dynamic agency predictions to corporate finance." reponame:Repositório Institucional do FGV, 2017. http://hdl.handle.net/10438/18243.
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This papers tests theoretical predictions concerning to agent compensation, debt structure and investment in the models of dynamic agency in DeMarzo and Fishman (2007), DeMarzo and Sannikov (2006) and DeMarzo, Fishman, He and Wang (2012). The results related to agent compensation are consistent with the patterns predicted in the models, indicating that the firm-years that the models would have as more likely to pay dividends are indeed the ones more likely to pay; also, among firms that pay dividends, more profits generate higher dividend payments and higher executive compensation, as predicted in the models. The prediction that firms that go well and reach a payment threshold present marginal q equal to average q, and thus after controlling for average q cash flows would not explain investment is also supported by the tests in here. On the other hand, predictions related to the role of the credit line and to the debt structure are not compatible with the results in here. The credit line doesn’t seem to be the provider of financial slack that protects the firm from low cash flows and also doesn’t seem to have the dynamics of being paid when profits are high and being more used when profits are low.
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Hensel, Nicholas (Nicholas Charles). "Development of a human body upper arm dynamic model for compensation and control of a body mounted robot." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111755.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 77-78).
Supernumerary Robotic Limbs (SRLs) are robotic manipulators worn on the human body which seek to augment the abilities of their wearers. A critical element to the design and implementation of these robotic systems is the development of a control framework which allows for intuitive control. The control of SRLs is further complicated by the relative motion of the manipulator with respect to its environment due to motion of the human body. Developing a dynamic model of the human body on which an SRL is mounted can serve as a useful tool, both for understanding the configuration of the SRL with respect to its user and for controlling the mechanism given a well-structured task process model. Subspace identification was investigated as a possible technique for generating a dynamic model of the human body from a set of defined input and output data. To validate the potential applicability of this approach, a simulated system was developed to model simple human arm reaching motions. From this simulated system, a set of virtual measurements were made to construct input/ output data sets. Subspace identification applied to these data sets indicated the applicability of the approach. Further testing was then conducted via the development of an experimental system for measuring actual human reaching motions. Using appropriate measurements, the simulation framework was reproduced with a physical system. Applying subspace identification techniques to the real data, a dynamic model was produced which could effectively reproduce the arm configuration. The success of both the simulated and experimental systems indicates that subspace techniques may be appropriate for generating human body dynamic models.
by Nicholas Hensel.
S.M.
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Hamza-Lup, Felix George. "DYNAMIC SHARED STATE MAINTENANCE IN DISTRIBUTED VIRTUAL ENVIRONMENTS." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4407.
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Advances in computer networks and rendering systems facilitate the creation of distributed collaborative environments in which the distribution of information at remote locations allows efficient communication. Particularly challenging are distributed interactive Virtual Environments (VE) that allow knowledge sharing through 3D information. In a distributed interactive VE the dynamic shared state represents the changing information that multiple machines must maintain about the shared virtual components. One of the challenges in such environments is maintaining a consistent view of the dynamic shared state in the presence of inevitable network latency and jitter. A consistent view of the shared scene will significantly increase the sense of presence among participants and facilitate their interactive collaboration. The purpose of this work is to address the problem of latency in distributed interactive VE and to develop a conceptual model for consistency maintenance in these environments based on the participant interaction model. A review of the literature illustrates that the techniques for consistency maintenance in distributed Virtual Reality (VR) environments can be roughly grouped into three categories: centralized information management, prediction through dead reckoning algorithms, and frequent state regeneration. Additional resource management methods can be applied across these techniques for shared state consistency improvement. Some of these techniques are related to the systems infrastructure, others are related to the human nature of the participants (e.g., human perceptual limitations, area of interest management, and visual and temporal perception). An area that needs to be explored is the relationship between the dynamic shared state and the interaction with the virtual entities present in the shared scene. Mixed Reality (MR) and VR environments must bring the human participant interaction into the loop through a wide range of electronic motion sensors, and haptic devices. Part of the work presented here defines a novel criterion for categorization of distributed interactive VE and introduces, as well as analyzes, an adaptive synchronization algorithm for consistency maintenance in such environments. As part of the work, a distributed interactive Augmented Reality (AR) testbed and the algorithm implementation details are presented. Currently the testbed is part of several research efforts at the Optical Diagnostics and Applications Laboratory including 3D visualization applications using custom built head-mounted displays (HMDs) with optical motion tracking and a medical training prototype for endotracheal intubation and medical prognostics. An objective method using quaternion calculus is applied for the algorithm assessment. In spite of significant network latency, results show that the dynamic shared state can be maintained consistent at multiple remotely located sites. In further consideration of the latency problems and in the light of the current trends in interactive distributed VE applications, we propose a hybrid distributed system architecture for sensor-based distributed VE that has the potential to improve the system real-time behavior and scalability.Ph.D.
School of Computer Science;
Engineering and Computer Science;
Engineering and Computer Science
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Mao, Yincan. "Passive Balancing of Switching Transients between Paralleled SiC MOSFETs." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82203.
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The SiC MOSFET has attracted interest due to its superior characteristics compared to its Si counterpart. Several SiC MOSFETs are usually paralleled to increase current capability, considering cost effectiveness and manufacturability. Current unbalance among the MOSFETs is a concern as it affects reliability. The two main causes are asymmetrical layout and parameter mismatch. The variation in parameters, unlike circuit or module layout, is unavoidable during production. Among all the parameters of MOSFET, the spreads in on-state resistance (Rds(on)) and threshold voltage (Vth) are the major concerns during paralleling. The disparity in Rds(on) causes static current unbalance which is self-limited due to the positive temperature coefficient of Rds(on). Its influence is not investigated here. The threshold voltage Vth has a negative temperature coefficient, forcing the MOSFET with lower Vth to carry more current during switching transient. Paralleled MOSFETs are usually de-rated to guarantee safe operation. Balancing of peak currents during switching transient isthe goal of this work.
Integration of current/voltage sensors into paralleled structure is difficult in real application. Complicated feedback loop design and separate gate drivers also need to be avoided in perspective of cost and volume. Passive balancing solutions are investigated in this dissertation. The inductors and resistors most effective in improving current sharing are identified by parametric analysis. Their current balancing mechanisms are analyzed in circuit point of view. The design guidelines involving the magnitude of Vth mismatch, current rise time, and unbalance percentage are derived for the selection of passive components. The theory upholds well when substantial parasitics from device package and layout exist.
Several passive balancing structures are analyzed and compared in terms of current balancing capability, voltage stress, total switching loss, and switching loss difference. All of them can provide much better current and power balancing without increasing switching loss. Some of the them may increase the stress-inducing inductance, which can be reduced by negative magnetic coupling. Perfect coupling between power-source inductors would enable current matching without penalty on voltage stress.
Common-source inductance (Lcm) is effective in dynamic balancing, but at the expense of higher switching loss. It is not considered in power module application because Kelvin connection is normally applied. However, wire bond inside the package of discrete MOSFETs and part of the external leads are inevitable and add to Lcm. Peak-current and switching energy mismatches vary with operating conditions (including input voltage, input current, and switching speed). Design guidelines and procedures that are valid for wide operating range are provided for cases with and without Lcm.
This dissertation also models the switching energy and switching energy mismatch of paralleled MOSFETs. The influence of operating conditions, passive balancing components, layout and package parasitic inductances, nonlinear channel performance, and voltage dependent parasitic capacitors are included in the modeling process. The resulting high order system is simplified by reducing the number of passive components and number of devices without losing accuracy. The influence of current balancing components and magnitude of threshold voltage mismatch on sharing are discussed based on modeling results.
In conclusion, this dissertation balances the transient currents between paralleled SiC MOSFETs automatically by inductance, resistance and magnetic coupling. This procedure is done utilizing one gate driver without current/voltage sensors and feedback loop. Those solutions work for both polarities of Vth mismatch and force balancing from the first current peak. Design guidelines involving the magnitude of Vth mismatch, current rise time, and maximum peak-current difference are derived to guide the choice of passive components. The detail design procedures are recommended to force currents to share over wide operating range. The aforementioned benefits are demonstrated by two paralleled SiC MOSFETs (C2M0160120D) tested at variant operating conditions. The difference of peak currents can be reduced below 5% of steady-state current in every switching transient. Switching energy mismatch percentage can be reduced by 6 times without increasing total switching energy.Ph. D.
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Piwkowska, Zuzanna. "Interactions en temps réel entre neurones corticaux et modèles computationnels : analyse de conductances synaptiques et compensation numérique des artéfacts d'électrode." Paris 6, 2007. http://www.theses.fr/2007PA066250.
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Grâce au dynamic-clamp, une technique d’électrophysiologie pour l’injection en temps réel de conductances artificielles, nous avons validé in vitro des méthodes d’extraction des propriétés statistiques des conductances synaptiques à partir du potentiel de membrane de neurones corticaux, et montré que le ratio des variances des conductances excitatrices et inhibitrices déterminait leur contrôle relatif du déclenchement d’un potentiel d’action. Nous avons aussi développé une nouvelle technique de compensation active (AEC) de la réponse de l’électrode intracellulaire au passage du courant, basée sur un modèle numérique de l’électrode interagissant en temps réel avec le poste d’enregistrement. Nos tests avec des électrodes fines de haute résistance dans des neurones corticaux in vitro montrent une performance améliorée de l’AEC par rapport aux méthodes traditionnelles, ce qui permettra d’étendre à de nouvelles préparations l’application du dynamic-clamp à haute résolution temporelle
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Oturkar, Siddharth A. "Push Recovery of Humanoid Robot Using Thruster and Acceleration Compensation." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339752428.
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Hernandez, Lopezomoza Mario Andres. "Cadre de travail généralisé de compensation non-linéaire robuste : application à la rentrée atmosphérique." Thesis, Toulouse, ISAE, 2012. http://www.theses.fr/2012ESAE0022/document.
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Ce travail de thèse est consacré à l'extension de l'Inversion Dynamique non-linéaire (NDI-Nonlinear Dynamic Inversion) pour un ensemble plus grand de systèmes non-linéaires, tout en garantissant des conditions de stabilité suffisantes. La NDI a été étudiée dans le cas de diverses applications, y compris en aéronautique et en aérospatiale. Elle permet de calculer des lois de contrôle capables de linéariser et de découpler un modèle non-linéaire à tout point de fonctionnement de son enveloppe d'état. Cependant cette méthode est intrinsèquement non-robuste aux erreurs de modélisation et aux saturations en entrée. En outre, dans un contexte non-linéaire, l'obtention d'une garantie quantifiable du domaine de stabilité atteint reste à l'heure actuelle complexe. Contrairement aux approches classiques de la NDI, notre méthodologie peut être considérée comme un cadre de compensation non-linéaire généralisé qui permet d'intégrer les incertitudes et les saturations en entrée dans le processus de conception. En utilisant des stratégies de contrôle antiwindup, la loi de pilotage peut être calculée grâce à un simple processus en deux phases. Dans ce cadre de travail généralisé des transformations linéaires fractionnaires (LFT - Linear Fractional Transformations) de la boucle fermée non-linéaire peuvent être facilement déduites pour l'analyse de la stabilité robuste en utilisant des outils standards pour de systèmes linéaires. La méthode proposée est testée pour le pilotage d'un véhicule de rentrée atmosphérique de type aile delta lors de ses phases hypersonique, transsonique et subsonique. Pour cette thèse, un simulateur du vol incluant divers facteurs externes ainsi que des erreurs de modélisation a été développé dans SimulinkThis thesis work is devoted to extending Nonlinear Dynamic Inversion (NDI) for a large scale of nonlinear systems while guaranteeing sufficient stability conditions. NDI has been studied in a wide range of applications, including aeronautics and aerospace. It allows to compute nonlinear control laws able to decouple and linearize a model at any operating point of its state envelope. However, this method is inherently non-robust to modelling errors and input saturations. Moreover, obtaining a quantifiable guarantee of the attained stability domain in a nonlinear control context is not a very straightforward task. Unlike standard NDI approaches, our methodology can be viewed as a generalized nonlinear compensation framework which allows to incorporate uncertainties and input saturations in the design process. Paralleling anti-windup strategies, the controller can be computed through a single multichannel optimization problem or through a simple two-step process. Within this framework, linear fractional transformations of the nonlinear closed-loop can be easily derived for robust stability analysis using standard tools for linear systems. The proposed method is tested for the flight control of a delta wing type reentry vehicle at hypersonic, transonic and subsonic phases of the atmospheric reentry. For this thesis work, a Flight Mechanics simulator including diverse external factors and modelling errors was developed in Simulink
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Naeli, Kianoush. "Optimization of piezoresistive cantilevers for static and dynamic sensing applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28247.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Brand, Oliver; Committee Member: Adibi, Ali; Committee Member: Allen, Mark G.; Committee Member: Bottomley, Lawrence A.; Committee Member: Degertekin, F. Levent.
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Calvino, Flavio. "Employment dynamics and innovation." Thesis, Paris 1, 2016. http://www.theses.fr/2016PA01E034.
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Cette thèse de doctorat porte sur la dynamique de l’emploi dans les entreprises et sur la relation entre la dynamique de l’emploi et l’innovation, avec une attention particulière portée sur les entreprises nouvellement créées. Cette thèse conceptualise théoriquement et analyse empiriquement les différents aspects de l’interaction complexe entre le changement technologique et la dynamique de l’emploi, en se concentrant sur les effets hétérogènes des différents types d’innovation sur la croissance de l’emploi. Compte tenu le rôle primordial joué par les nouvelles et jeunes entreprises dans le processus de destruction créatrice et leur apport à la création globale de l’emploi, cette thèse fournit une caractérisation de la contribution nette d’emplois des nouvelles entreprises dans un nombre important de pays, en utilisant des données micro-agrégées issues d’une nouvelle base de données. En outre, elle analyse comment un certain nombre de caractéristiques institutionnelles affectent la création nette d’emplois dans les start-ups, en se concentrant sur les effets hétérogènes des politiques sur les nouvelles entreprises et les entreprises déjà existantes. Cette thèse étudie enfin une caractéristique particulière des lois de distribution des taux de croissance de l’emploi, c’est-à-dire la volatilité de la croissance de l’emploi, que non seulement se révèle être une médiation cruciale des effets des politiques sur la création nette d’emplois, mais a aussi d’importantes implications à la fois micro- et macroéconomiquesThis doctoral thesis focuses on employment dynamics in firms, and on the relationship between employment dynamics and innovation, with a particular focus on the entry process. It conceptualizes theoretically and analyses empirically different aspects of the complex interaction between technical change and employment dynamics, focusing on the heterogeneous effects of different types of innovation on employment growth. In the light of the prominent role of newly-born firms in shaping the creative destruction process and contributing to overall job creation, this thesis provides a characterization of the net job contribution by surviving entrants across a significant number of countries. Using newly collected representative micro-aggregated data, it further analyses whether and how a number of institutional characteristics affect start-ups’ net job creation, focusing on the heterogeneous effects of policies on entrants and incumbents. This thesis finally characterizes a particular feature of the employment growth distributions – employment growth volatility – that not only proves to be crucially mediating the effects of policies on entrants’ net job creation, but also has important micro and macroeconomic implications
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Momey, Fabien. "Reconstruction en tomographie dynamique par approche inverse sans compensation de mouvement." Phd thesis, Université Jean Monnet - Saint-Etienne, 2013. http://tel.archives-ouvertes.fr/tel-00842572.
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La tomographie est la discipline qui cherche à reconstruire une donnée physique dans son volume, à partir de l'information indirecte de projections intégrées de l'objet, à différents angles de vue. L'une de ses applications les plus répandues, et qui constitue le cadre de cette thèse, est l'imagerie scanner par rayons X pour le médical. Or, les mouvements inhérents à tout être vivant, typiquement le mouvement respiratoire et les battements cardiaques, posent de sérieux problèmes dans une reconstruction classique. Il est donc impératif d'en tenir compte, i.e. de reconstruire le sujet imagé comme une séquence spatio-temporelle traduisant son "évolution anatomique" au cours du temps : c'est la tomographie dynamique. Élaborer une méthode de reconstruction spécifique à ce problème est un enjeu majeur en radiothérapie, où la localisation précise de la tumeur dans le temps est un prérequis afin d'irradier les cellules cancéreuses en protégeant au mieux les tissus sains environnants. Des méthodes usuelles de reconstruction augmentent le nombre de projections acquises, permettant des reconstructions indépendantes de plusieurs phases de la séquence échantillonnée en temps. D'autres compensent directement le mouvement dans la reconstruction, en modélisant ce dernier comme un champ de déformation, estimé à partir d'un jeu de données d'acquisition antérieur. Nous proposons dans ce travail de thèse une approche nouvelle ; se basant sur la théorie des problèmes inverses, nous affranchissons la reconstruction dynamique du besoin d'accroissement de la quantité de données, ainsi que de la recherche explicite du mouvement, elle aussi consommatrice d'un surplus d'information. Nous reconstruisons la séquence dynamique à partir du seul jeu de projections courant, avec pour seules hypothèses a priori la continuité et la périodicité du mouvement. Le problème inverse est alors traité rigoureusement comme la minimisation d'un terme d'attache aux données et d'une régularisation. Nos contributions portent sur la mise au point d'une méthode de reconstruction adaptée à l'extraction optimale de l'information compte tenu de la parcimonie des données -- un aspect typique du problème dynamique -- en utilisant notamment la variation totale (TV) comme régularisation. Nous élaborons un nouveau modèle de projection tomographique précis et compétitif en temps de calcul, basé sur des fonctions B-splines séparables, permettant de repousser encore la limite de reconstruction imposée par la parcimonie. Ces développements sont ensuite insérés dans un schéma de reconstruction dynamique cohérent, appliquant notamment une régularisation TV spatio-temporelle efficace. Notre méthode exploite ainsi de façon optimale la seule information courante à disposition ; de plus sa mise en oeuvre fait preuve d'une grande simplicité. Nous faisons premièrement la démonstration de la force de notre approche sur des reconstructions 2-D+t à partir de données simulées numériquement. La faisabilité pratique de notre méthode est ensuite établie sur des reconstructions 2-D et 3-D+t à partir de données physiques "réelles", acquises sur un fantôme mécanique et sur un patient
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Zamperin, Joao Luiz Bergamo. "Método analítico para análise da estabilidade do gerador assíncrono através do monitoramento da tensão /." Ilha Solteira : [s.n.], 2011. http://hdl.handle.net/11449/99856.
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Orientador: Laurence Duarte ColvaraBanca: Dionizio Paschoareli Junior
Banca: Walmir de Freitas Filho
Resumo: Propõe-se neste trabalho o desenvolvimento de uma metodologia analítica para análise do desempenho dinâmico/transitório dos geradores de indução conectados ao sistema de energia elétrica. O método proposto para o estudo da estabilidade das máquinas de indução baseia-se no monitoramento da tensão interna E' durante o período transitório do sistema, a qual pode comprometer a capacidade de transmissão de potência na linha, com consequente colapso da estabilidade da máquina. Deste modo, faz-se a análise do desempenho transitório da máquina pela observação da grandeza em que efetivamente reside a causa da instabilidade. O método desenvolvido foi validado por meio de simulações digitais, em duas configurações do sistema: o primeiro caso, desprezando o suporte de potência reativa, para efeito de análise nos estudos de estabilidade transitória. No segundo, é realizada a compensação dinâmica de potência reativa via SVC (Static Var Compensator). Neste caso, mesmo na presença do compensador variável de reativo, o método da tensão interna revelou-se capaz de avaliar novos limites de estabilidade para o sistema. Considerados os resultados obtidos, observa-se que o método proposto apresenta resultados suficientemente precisos para avaliar o comportamento dos geradores de indução conectados à rede elétrica
Abstract: This dissertation proposes the development of an analytical methodology for analysis of dynamic/transient performance of an induction generator connected to a bulk power system. The proposed method for studying the stability of induction machines is based on monitoring the internal voltage named E' since during the transient system, its magnitude may decrease and so causing degeneration of the transmission system capability, with consequent collapse of machine stability. Thus it is the analysis of transient performance of the machine by observing the variable that is actually the cause of instability. The analytical method was validated by means of digital simulations, in two system configurations: in the first case, no reactive support is considered, and the purpose is to analyse the machine transient stability itself. In the second, a reactive support is provided by means of the dynamic reactive compensation via SVC (Static Var Compensator). In this case, even in the presence of variable reactive compensator, the method of internal voltage proved to be able to properly assess new stability limits. The results so obtained lead to the indication that the proposed method results are accurate enough in order to evaluate the behavior of induction generators, connected to the power grid
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Wang, Yonglian. "Speech Recognition under Stress." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1968468151&sid=9&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Schwartz, Timothée. "Les dispositifs artificiels au service de la restauration et de la compensation écologique : de l’évaluation du risque de piège écologique aux recommandations de bonnes pratiques." Thesis, Université Paris sciences et lettres, 2020. https://tel.archives-ouvertes.fr/tel-03177394.
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Pour faire face aux changements rapides de l’environnement induits par l’Homme, de nombreuses politiques publiques de protection de la nature ont été mises en place. Parmi celles-ci, les mesures compensatoires conduisent à restaurer des habitats d’espèces, qui peuvent cependant créer des pièges écologiques. Ce risque est particulièrement grand pour les dispositifs artificiels, largement plébiscités, dont il est aujourd’hui crucial d’évaluer l’impact sur les populations. Dans cette thèse, à travers les exemples du Rollier d’Europe et des Laridés coloniaux nichant dans le Sud de la France, je montre que le test de l’hypothèse de piège écologique est bien adapté à l’évaluation des dispositifs artificiels, et est généralisable à d’autres contextes. L’étude de mécanismes de création des pièges permet également la formulation de recommandations. Je propose une démarche adaptative pour la conception, la mise en œuvre et l’évaluation des projets de restauration et de compensation écologiqueIn order to cope with the human induced rapid environmental changes, many public actions for the protection of nature have been undertaken. Among these are those biodiversity offsetting measures that can enable the restoration of species habitats. These can however create ecological traps. This risk is particularly great for artificial devices which have been widely acclaimed but whose impact on the target populations is often untested. In this thesis, I use the examples of the European roller and the colonial Laridae breeding in the south of France, to show that the test of the ecological trap hypothesis is well adapted to the evaluation of artificial devices, and is generalizable to other contexts. The study of trap creation mechanisms also allows the formulation of good practice recommendations. I propose an adaptive approach for the design, implementation and evaluation of restoration and biodiversity offsetting projects
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Zimouche, Hakim. "Capteur de vision CMOS à réponse insensible aux variations de température." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00656381.
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Les capteurs d'images CMOS sont de plus en plus utilisés dans le domaine industriel : la surveillance, la défense, le médical, etc. Dans ces domaines, les capteurs d'images CMOS sont exposés potentiellement à de grandes variations de température. Les capteurs d?images CMOS, comme tous les circuits analogiques, sont très sensibles aux variations de température, ce qui limite leurs applications. Jusqu'à présent, aucune solution intégrée pour contrer ce problème n'a été proposée. Afin de remédier à ce défaut, nous étudions, dans cette thèse, les effets de la température sur les deux types d'imageurs les plus connus. Plusieurs structures de compensation sont proposées. Elles reprennent globalement les trois méthodes existantes et jamais appliquées aux capteurs d'images. La première méthode utilise une entrée au niveau du pixel qui sera modulée en fonction de l'évolution de la température. La deuxième méthode utilise la technique ZTC (Zero Température Coefficient). La troisième méthode est inspirée de la méthode de la tension de référence bandgap. Dans tous les cas, nous réduisons de manière très intéressante l'effet de la température et nous obtenons une bonne stabilité en température de -30 à 125°C. Toutes les solutions proposées préservent le fonctionnement initial de l'imageur. Elles n'impactent également pas ou peu la surface du pixel
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Schaal, Peter. "Observer-based engine air charge characterisation : rapid, observer-assisted engine air charge characterisation using a dynamic dual-ramp testing method." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/33247.
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Characterisation of modern complex powertrains is a time consuming and expensive process. Little effort has been made to improve the efficiency of testing methodologies used to obtain data for this purpose. Steady-state engine testing is still regarded as the golden standard, where approximately 90% of testing time is wasted waiting for the engine to stabilize. Rapid dynamic engine testing, as a replacement for the conventional steady-state method, has the potential to significantly reduce the time required for characterisation. However, even by using state of the art measurement equipment, dynamic engine testing introduces the problem that certain variables are not directly measurable due to the excitation of the system dynamics. Consequently, it is necessary to develop methods that allow the observation of not directly measurable quantities during transient engine testing. Engine testing for the characterisation of the engine air-path is specifically affected by this problem since the air mass flow entering the cylinder is not directly measurable by any sensor during transient operation. This dissertation presents a comprehensive methodology for engine air charge characterisation using dynamic test data. An observer is developed, which allows observation of the actual air mass flow into the engine during transient operation. The observer is integrated into a dual-ramp testing procedure, which allows the elimination of unaccounted dynamic effects by averaging over the resulting hysteresis. A simulation study on a 1-D gas dynamic engine model investigates the accuracy of the developed methodology. The simulation results show a trade-off between time saving and accuracy. Experimental test result confirm a time saving of 95% compared to conventional steady-state testing and at least 65% compared to quasi steady-state testing while maintaining the accuracy and repeatability of conventional steady-state testing.
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El, bitar Khalil. "Clearing vectors in financial networks." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2079/document.
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Le risque systémique menaçant le système financier est une préoccupation majeure pour les régulateurs. Les indicateurs adéquats de risque systémique devraient vraiment les aider à accomplir les lois réglementaires appropriées. La thèse propose un modèle dynamique du système bancaire pour calculer un indicateur de risque systémique de deux composantes :La probabilité d'un évènement déclencheur qui provient de la baisse des prix des actifs, et les pertes correspondantes dans le système Financier.La thèse prouve également l'existence et l'unicité de deux modèles d'équilibre de compensation : Le premier avec un modèle de différentes hiérarchies de dette et le second modèle avec plusieurs stratégies de liquidationSystemic risk threatening the financial system is a major concern for regulators. Adequate indicators of systemic risk would help them perform appropriate regulatory laws.The thesis proposes a dynamic model of banking system to calculate a systemic risk indicator of two components : The probability of a triggering event originated from external asset price decline, and the corresponding losses through the financial system. The thesis also proves the existence and uniqueness of two clearing equilibrium: the first deals with a model of différent debt seniorities, the second with a model of several illiquid asset following a proportional liquidation strategy
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Horenský, Martin. "Dynamická kompenzace." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220932.
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This master’s thesis is focusing on compensation of reactive power, especially on creating demonstrative model of static var compensation unit (SVC). Main topic of thesis is to apply this device for fast balancing dynamic conversions of recieved reactive power. In theoretical part is described suitable method for determination of instantaneous power. Next, there is basic description of all means used for compensation of reactive power and detailed description of the SVC compensator. Practical part includes design of compensation unit and control program in LabVIEW. The pq theory is implemented for detection instantaneous power. The results of validating functionality of compensator are presented in the last part of thesis.
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Hoarau, Gwenaël. "Étude de la limite de détection et des fausses alarmes émises par les moniteurs de mesure de la contamination radioactive atmosphérique dans les chantiers de démantèlement." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP055.
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Les moniteurs de mesure de la contamination radioactive atmosphérique sont utilisés dans les installations nucléaires afin d’assurer la radioprotection des travailleurs vis-à-vis de l’exposition aux aérosols radioactifs. Les performances de ces moniteurs sont évaluées dans des conditions normatives IEC, lesquelles couvrent une large gamme d’atmosphères de travail. Dans des situations typiques de celles mesurées en chantier de démantèlement nucléaire, lesquelles sont d’ailleurs hors cadre IEC, un comportement inattendu des moniteurs de mesure de la contamination radioactive atmosphérique est souvent observé. Celui-ci correspond à l’émission d’une alarme de type faux positif. L’objectif de ce travail de thèse est d’améliorer les connaissances sur le comportement des moniteurs de mesure de la contamination radioactive atmosphérique dans des situations hors conditions normative IEC. Pour ce faire, un dispositif expérimental spécifique a été conçu, à l’intérieur duquel la reproduction d’atmosphères typiques de celles mesurées en chantier de démantèlement est possible. Ainsi, ce dispositif a rendu possible l’étude en laboratoire du comportement d’un moniteur de mesure de la contamination radioactive atmosphérique de type ABPM203M. Cette étude expérimentale a permis d’une part, de mettre en avant les conditions qui conduisent à un comportement inattendu du moniteur et d’autre part, de démontrer les raisons pour lesquelles une alarme de type faux positif est souvent émise dans ces conditions hors IEC. A la synthèse des résultats de l’étude, un procédé nouveau de mesure a été proposé, lequel permet d’une part, de considérer à la fois les caractéristiques des aérosols non-radioactifs et celles des aérosols radioactifs et d’autre part, d’améliorer la mesure effectuée par le moniteur permettant de toujours assurer la radioprotection des travailleursThe Continuous Air monitors are used in the nuclear facilities for ensuring the radiation protection of workers who are likely to be confronted to radioactive aerosols. The CAM behavior are evaluated under IEC normative conditions. In atmospheric conditions as measured in decommissioning nuclear sites, outside of IEC, wrongs CAM behavior are observed. Which correspond to the false positives triggering. The aim of this thesis work is to enhance the knowledge about the CAM behavior when it is faced to outside IEC normative conditions. A specific experimental chamber has been designed, inside which the reproduction of the dismantling nuclear site atmosphere is achievable. Thus, this experimental chamber made it possible, in the laboratory, the study of the behavior of a CAM type ABPM203M. With the results we have, on the one hand, highlighted the conditions which lead to unexpected behavior of the CAM and, on the other hand, demonstrated the reasons why a false positive alarm is often emitted under these conditions, outside IEC. At the synthesis of the results of the study, a new measurement process was proposed, which makes it possible, on the one hand, to consider both the characteristics of non-radioactive aerosols and those of radioactive aerosols and on the other hand, to improve the measurement achieved out by the CAM to always ensure the radiation protection of workers
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Zamperin, João Luiz Bergamo [UNESP]. "Método analítico para análise da estabilidade do gerador assíncrono através do monitoramento da tensão." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/99856.
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Propõe-se neste trabalho o desenvolvimento de uma metodologia analítica para análise do desempenho dinâmico/transitório dos geradores de indução conectados ao sistema de energia elétrica. O método proposto para o estudo da estabilidade das máquinas de indução baseia-se no monitoramento da tensão interna E' durante o período transitório do sistema, a qual pode comprometer a capacidade de transmissão de potência na linha, com consequente colapso da estabilidade da máquina. Deste modo, faz-se a análise do desempenho transitório da máquina pela observação da grandeza em que efetivamente reside a causa da instabilidade. O método desenvolvido foi validado por meio de simulações digitais, em duas configurações do sistema: o primeiro caso, desprezando o suporte de potência reativa, para efeito de análise nos estudos de estabilidade transitória. No segundo, é realizada a compensação dinâmica de potência reativa via SVC (Static Var Compensator). Neste caso, mesmo na presença do compensador variável de reativo, o método da tensão interna revelou-se capaz de avaliar novos limites de estabilidade para o sistema. Considerados os resultados obtidos, observa-se que o método proposto apresenta resultados suficientemente precisos para avaliar o comportamento dos geradores de indução conectados à rede elétrica
This dissertation proposes the development of an analytical methodology for analysis of dynamic/transient performance of an induction generator connected to a bulk power system. The proposed method for studying the stability of induction machines is based on monitoring the internal voltage named E' since during the transient system, its magnitude may decrease and so causing degeneration of the transmission system capability, with consequent collapse of machine stability. Thus it is the analysis of transient performance of the machine by observing the variable that is actually the cause of instability. The analytical method was validated by means of digital simulations, in two system configurations: in the first case, no reactive support is considered, and the purpose is to analyse the machine transient stability itself. In the second, a reactive support is provided by means of the dynamic reactive compensation via SVC (Static Var Compensator). In this case, even in the presence of variable reactive compensator, the method of internal voltage proved to be able to properly assess new stability limits. The results so obtained lead to the indication that the proposed method results are accurate enough in order to evaluate the behavior of induction generators, connected to the power grid
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Oueslati, Marouene. "Contribution à la modélisation dynamique, l'identification et la synthèse de lois de commande adaptées aux axes flexibles d'un robot industriel." Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2013. http://pastel.archives-ouvertes.fr/pastel-01016462.
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Les robots industriels représentent un moyen de production sophistiqués pour l'industrie manufacturière d'aujourd'hui. Ces manipulateurs sont plus agiles, plus flexibles et moins coûteux que les machines-outils spécialisées. L'exploitation de ces avantages fait l'objet d'une demande croissante de l'industrie. La dynamique de ces manipulateurs est soumise à des nombreuses sources d'imprécision. En effet les défauts de la chaîne de transmission, ou encore les éléments de liaisons peuvent être le siège de déformations et de vibrations dégradant sensiblement leur précision. Ces phénomènes physiques sont d'autant plus difficiles à compenser que seul un sous ensemble des états du système est mesuré par les codeurs moteurs. La structure de commande industrielle actuelle d'un robot n'agit donc pas directement sur ces phénomènes. Il est nécessaire alors de progresser sur le front de l'amélioration de la précision par l'adaptation de la commande à ces nouvelles exigences. Un état de l'art met en évidence un manque de travaux qui traitent de l'élaboration d'anticipations adaptées aux axes d'un robot et intégrant les phénomènes de déformation. En outre, la planification de trajectoire n'est classiquement pas remise en cause et peu évoquée. Elle représente pourtant un moyen d'action éprouvé afin d'améliorer les performances dynamiques en suivi de profil. L'approche proposée dans ce mémoire se veut une alternative à ces méthodes. Elle est basée sur une exploitation d'un modèle dynamique représentatif et détaillé. Il intègre les principaux phénomènes physiques mis en évidence tels que les effets de la gravité, les systèmes mécaniques de compensation, les forces de frottement et la flexibilité articulaire. Cette modélisation associée à des méthodes d'identification expérimentale est exploitée afin de déduire une structure de commande. Elle permet la réduction des déformations élastiques et des vibrations par une action sur la précommande et sur la loi de mouvement adaptée. Ainsi, nous introduisons une méthode d'estimation non asymptotique appliquée en robotique, afin d'estimer rapidement les paramètres vibratoires de ce dernier et contribue à une réactualisation des modèles exploités. Des résultats expérimentaux montrent que cette méthodologie mène à une amélioration des performances de positionnement par rapport à la commande industrielle.
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Ramalingam, Nagarajan. "Non-contact multispectral and thermal sensing techniques for detecting leaf surface wetness." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1104392582.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxii, 271 p.; also includes graphics (some col.) Includes bibliographical references (p. 206-214).
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George, Kiranraj. "Design and Performance Evaluation of 1 Giga Hertz Wideband Digital Receiver." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1183662240.
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Fu, Shiming. "Dynamic Capital Budgeting, Compensation, and Security Design." Diss., 2015. http://hdl.handle.net/10161/10454.
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This thesis examines how various agency frictions affect corporate financing, capital budgeting, managerial compensation and investment in dynamic settings. In the internal capital budgeting process, the agency issues considered are (i) the division manager privately observes project arrival and quality, and (ii) he can divert allocated capital. The optimal capital budgeting and compensation policies are jointly designed to mitigate agency costs that are endogenously determined. When the division's financial slack is low, positive NPV investments are possibly forgone and manager's pay-performance sensitivity is kept small. When the division's financial slack is high, projects are funded more efficiently and steeper incentives are provided. In the process of external financing, the key friction considered is that the agent has persistent private information about firm performance. In the optimal contract, the firm is financed by outside equity and a credit line contingent on compliance with a cash flow covenant. The agent is compensated via a combination of equity and stock options. As the level of persistence increases, the agent holds less equity and more stock options; the investors hold more equity. Investment is possibly efficient in the constrained firm and is varying with cash flow in the unconstrained firm.
Dissertation
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Chang, Yun, and 常雲. "Dynamic and Unbalance Voltage Compensation Using STATCOM." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/77864677544321383466.
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碩士國立中正大學
電機工程所
96
The high-precision devices become increasingly popular as the high-tech industry rises. This brings much attention to the problems of power quality. Commonly seen problems are mainly caused by fluctuations on heavy loads, non-linear loads, faults and many others. This thesis will address problems of voltage quality, focusing on voltage flicker, voltage sag/dip, voltage unbalance, and investigate their causes, standards and impacts to power systems. Among all Flexible AC Transmission Systems (FACTS), which are only recently being widely utilized, we applied a so-called Static Synchronous Compensator (STATCOM) to mitigate the voltage variation problems as aforementioned. This device possesses characteristics such as rapid response, and the ability to provide reactive power at low voltage. These characteristics help to actively supply or absorb reactive power to or from the system, ultimately achieving the function of voltage regulation. This thesis employs a Space Vector Pulse Width Modulation based controller to provide solutions for problems in voltage flicker and voltage sag/dip. In addition, solutions in voltage unbalance are also provided with two types of controllers; one controller compensates for the amplitude variation for phase voltages, the other controller compensates for the voltage of negative sequence. Controllers are then built in a software called Power System Computer Aided Design/ElectroMagnetic Trasient for DC (PSCAD/EMTDC), where various simulations of dynamic voltage variations are carried out. Investigations on the feasibilities of the control framework and the extent of the voltage quality improvements are also included. Lastly, the actual voltages measurements of an electric arc furnace taken from a steelwork factory are input into the PSCAD environment. Using the designed compensator to carry out simulations, STATCOM''s compensation outcome on the voltage of the actual electric arc furnace, and the extent to which it is capable of exerting its effect, are observed.
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Feng, Felix Zhiyu. "Dynamic Compensation and Investment with Limited Commitment." Diss., 2014. http://hdl.handle.net/10161/8721.
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In this dissertation I study the role of limited commitment in dynamic models. In the first part, I consider firms that face uncertainty shocks in a principal-agent setting but have only limited ability to commit to long-term contracts. Limited commitment firms expedite payments to their managers when uncertainty is high, a finding that helps to explain the puzzling large bonuses observed during the recent financial crisis. In the second part, I examine a dynamic investment model where firms invest in a risky asset but cannot hedge the risk of their investment because they lack the ability to commit to future repayments of debt. Once firms have access to exogenous supply of risk free assets they may, on the aggregate level, invest more in the risky asset because risk free technology allows them to grow richer in equilibrium. This result helps to explain the asset price booms in emerging countries when those countries experience substantial capital outflow.
Dissertation
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Chen, Yen-Bo, and 陳彥博. "A Dynamic Compensation Method for Biomedical Signal." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/xzgc56.
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碩士國立中興大學
資訊科學與工程學系
103
With the development of the wearable devices, the demand for personal physiological signal measurement devices will become more and more popular. We hope to provide users a wearable device with long time measurement capability. In this thesis, a front-end circuit of measurement for various biomedical signal is discussed to cope with the issues of external stray capacitance, common mode noise from environment, and DC offset existing in the circuit. We propose the compensation capacitance mechanism to neutralize the effect of stray capacitance, remove DC offset in low frequency component to avoid the signal saturation, and eliminate common mode noise with feedback approach. Our measurement uses piezo resistive sensor to capture vibration movement of radial artery on the wrist. In addition, we use wet electrode adhesive on the chest in Lead I to get the measurement of ECG signal. Finally, the output signal of the circuit is obtained as an input signal to the A/D interface of embedded platform. The wrist pulse and ECG signals can be obtained with qualified quality for back-end analysis by using an adjustable feedback mechanism.
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Akila, S. "Orbit Model Analysis And Dynamic Filter Compensation For Onboard Autonomy." Thesis, 2006. http://hdl.handle.net/2005/398.
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Orbit of a spacecraft in three dimensional Inertial Reference Frame is in general represented by a standard set of six parameters like Keplerian Orbital Elements namely semimajor axis, eccentricity, inclination, argument of perigee, right ascension of ascending node,
and true anomaly. An orbit can also be represented by an equivalent set of six parameters namely the position and velocity vectors, hereafter referred as orbit-vectors. The process of
determining the six orbital parameters from redundant set of observations (more than the required minimum observations) is known as Orbit Determination (OD) process. This is, in
general, solved using Least Squares principle. Availability of accurate, almost continuous, space borne observations provide tremendous scope for simplifications and new directions in Autonomous OD (AOD). The objective of this thesis is to develop a suitable scheme for
onboard autonomy in OD, specifically for low-earth-orbit-missions that are in high demand in the immediate future.
The focus is on adopting a simple orbit model by a thorough study and analysis by considering the individual contributions from the different force models or component accelerations acting on the spacecraft. Second step in this work is to address the application of an onboard estimation scheme like Kalman Filter for onboard processing. The impact of the approximation made in the orbit model for filter implementation manifests as propagation error or estimation residuals in the estimation. The normal procedure of tuning the filter is by
getting an appropriate state and measurement noise covariance matrices by some means, sometimes through trial and error basis. Since this tuning is laborious and the performance may vary with different contexts, it is attempted to propose a scheme on a more general footing, with dynamically compensating for the model simplification. There are three parts of this problem namely (i) Analysis of different Orbit Dynamics Models and selection of a
simplified Onboard Model (ii) Design of an Estimator Filter based on Kalman Filter approach for Onboard Applications and (iii) Development of a suitable Filter Compensation procedure to ensure best estimates of orbit vectors even with the simplified orbit model.
Development of a Numerical Integration scheme (and a software tool) and extensive simulation exercises to justify the conclusion on the simple model to be used in the estimation procedure forms the first part of the thesis.
Tables quantify the effect of individual accelerations and demonstrate the effects of various model components on orbit propagation. In general, it is well known that the atmospheric drag is a non-conservative force and reduces energy; it is also known that the effect of first zonal harmonic term is predominant than any other gravity parameters; such anticipated trends in the accuracies are obtained. This particular exercise is carried out for orbits of different altitudes and different inclinations. The analysis facilitates conclusions on a limited model orbit dynamics suitable for onboard OD. Procedures and results of this model selection analysis is published in Journal of Spacecraft Technology, Vol. 16, No.1,pp 8-30, Jan 2006, titled “Orbit Model Studies for Onboard Orbit Estimation” [69].
Design of Estimator based on Kalman Filter
There are two steps involved in dealing with the next part of the defined work:
• Design and implementation of Extended Kalman Filter Estimation (EKF) scheme
• Steps to compensate for approximation made in the reduced orbit dynamics
The GPS receivers on board some of the IRS satellites (for example, the Resource-Sat-1), output the GPS Navigation Solutions (GPSNS) namely the position and velocity vectors of
the IRS satellite along with the Pseudo-range measurements. These are recorded onboard for about two orbits duration, and are down loaded. An Extended Kalman Filter Algorithm for the estimation of the orbit vectors using these GPSNS observations is developed. Estimation is carried out assuming a Gaussian white noise models for the state and observation noises. The results show a strong dependence on the initial covariance of the noise involved; reconstruction of the observations results only if the assumption of realistic noise
characteristics (which are unknown) is strictly adhered. Hence this simple non-adaptive EKF is found inadequate for onboard OD scheme.
Development of the Dynamics Filter Compensation (DFC) Scheme
In next part of the thesis, the problem of dealing with the un-modeled accelerations has been addressed. A suitable model-compensation scheme that was first developed by D.S Ingram el at [60] and successfully applied to Lunar missions, has been modified suitably to treat the problem posed by the reduced orbit dynamics. Here, the un-modeled accelerations are approximated by the OU stochastic process described as the solution of the Langavin stochastic differential equation. A filter scheme is designed where the coefficients of the un-
modeled acceleration components are also estimated along with the system state yielding a better solution. Further augmentation to the filter include a standard Adaptive Measurement Noise covariance update; results are substantiated with actual data of IRS-P6 (Resource–Sat
1, see chapter 4).
Classified as the Structured Adaptive Filtering Scheme, this results in a Dynamic Filter Compensation(DFC) Scheme which provides distinctly improved results in the position of
the state.
First, the estimation is carried out using actual GPS Navigation Solutions as observations. What is to be estimated itself is observed; the State-Observation relation is simple. The
results are seen to improve the orbit position five times; bringing down the position error from 40 meters to about 8 meters. However, this scheme superimposes an extra factor of
noise in the velocity vector of the GPSNS solutions. It is noted that this scheme deals only with the process noise covariance. To tackle the noise introduced in the velocity components, modifications of the original scheme by introducing an adaptive measurement noise covariance update is done. This improves the position estimate further by about 2 meters and
also removes the noise introduced in the velocity components and reconstructs the orbit velocity vector output of the GPSNS. The results are confirmed using one more set of actual data corresponding to a different date. This scheme is shown to be useful for obtaining
continuous output –without data gaps- of the GPSNS output.
Next, the estimation is carried out taking the actual GPS observations which are the Pseudo Range, Range rate measurements from the visible GPS satellites (visible to the GPS receiver onboard ). Switching over to the required formulation for this situation in the state-measurement relation profile, estimation is carried out. The results are confirmed in this case
also. Clear graphs of comparisons with definitive orbital states (considered as actual) versus estimated states show that the model reduction attempted at the first part has been successfully tackled in this method.
In this era of space-borne GPS observations, where frequent sampling of the orbiting body is suggestive of reduced orbit models, an attempt for replacement of the conventional treatment of expensive and elaborate OD procedure is proved feasible in this thesis work.
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Yoder, Michael. "Adaptive compensation of dynamic characteristics of mechanical presses." 1994. http://catalog.hathitrust.org/api/volumes/oclc/33022755.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1994.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 91).
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Su, Guan-Yu, and 蘇冠宇. "Dynamic Analysis and Compensation for Micro-Machining Center." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/34451569279156462522.
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碩士國立雲林科技大學
機械工程系碩士班
97
The industrial products nowadays and in the future are becoming lighter, thinner, shorter and smaller. The shapes and structures of them are becoming much more complicated. However, the cost of components used in the equipment to manufacture these parts, such as linear PM motors, air-static bearings, and CNC control systems are very expensive. In this chapter, we investigated the methods of constructing precision machine tool with high positioning accuracy at comparatively low cost. In this study, we successfully integrated a commercial PC-Based Control System and a special linkage feed platform with very simple construction. To improve the static accuracy of the machine, laser measurement was used to obtain compensation data and the software is configured to achieve a maximum error of below 0.5 um. While the static accuracy was proven to be sufficient for micro-machining center, we have found the dynamic error has a very different characteristic compared to traditional ball screw feed system. Theoretical analysis, simulation and experiments were performed to explain the behavior. Finally, we compared the machine with linear motors and air-static bearings with the proposed machine with linkage mechanism. Results showed that the new structure can reach the precision required for micro-machining. The new machine has been demonstrated in the 2009 Taipei International Machine Tool Show ( 2009 TIMTOS ) and has earned a great deal of acclamations from both industry and academia.