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Dissertations / Theses on the topic 'Thread injection'
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1
Frei, Christian. "The thread injection : thread transport in circular pipe flow applied in a minimally invasive openporous implant system for endonasal surgery /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13549.
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Begleris, Philippos. "Three-dimensional flow predictions in motored diesel engines." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/7870.
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Attia, Usama M. "Micro-injection moulding of three-dimensional integrated microfluidic devices." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/4478.
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This thesis investigates the use of micro-injection moulding (μIM), as a high-volume process, for producing three-dimensional, integrated microfluidic devices. It started with literature reviews that covered three topics: μIM of thermoplastic microfluidics, designing for three-dimensional (3-D) microfluidics and functional integration in μIM. Research gaps were identified: Designing 3-D microfluidics within the limitations of μIM, process optimisation and the integration of functional elements. A process chain was presented to fabricate a three-dimensional microfluidic device for medical application by μIM. The thesis also investigated the effect of processing conditions on the quality of the replicated component. The design-of-experiments (DOE) approach is used to highlight the significant processing conditions that affect the part mass taking into consideration the change in part geometry. The approach was also used to evaluate the variability within the process and its effect on the replicability of the process. Part flatness was also evaluated with respect to post-filling process parameters. The thesis investigated the possibility of integrating functional elements within μIM to produce microfluidic devices with hybrid structures. The literature reviews highlighted the importance of quality control in high-volume micromoulding and in-line functional integration in microfluidics. A taxonomy of process integration was also developed based on transformation functions. The experimental results showed that μIM can be used to fabricate microfluidic devices that have true three-dimensional structures by subsequent lamination. The DOE results showed a significant effect of individual process variables on the filling quality of the produced components and their flatness. The geometry of the replicated component was shown to have effect on influential parameters. Other variables, on the other hand, were shown to have a possible effect on process variability. Optimization statistical tools were used to improve multiple quality criteria. Thermoplastic elastomers (TPE) were processed with μIM to produce hybrid structures with functional elements.
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Lundberg, Karl Johan. "Investigating the current state of securityfor small sized web applications." Thesis, Linköpings universitet, Databas och informationsteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-89160.
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It is not uncommon to read about hacker attacks in the newspaper today. The hackers are targeting governments and enterprises, and motives vary. It may be political or economic reasons, or just to gain reputation. News about smaller systems is, unsurprisingly, not as common. Does this mean that security is less relevant of smaller systems? This report investigates the threat model of smaller web applications, to answer that very question.Different attacks are described in the detail needed for explaining their threat but the intention is not to teach the reader to write secure code. The report does, however, provide the reader with a rich source of references for that purpose. After describing some of the worst threats, the general cloud threat model is analyzed. This is followed by a practical analysis of a cloud system, and the report is closed with general strategies for countering threats.The severe destruction that a successful attack may cause and the high prevalence of those attacks motivates some security practices to be performed whenever software is produced. Attacks against smaller companies are more common now than ever before
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Shahverdi, Hamidreza. "Characterization of three-phase flow and WAG injection in oil reservoirs." Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2549.
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Large quantities of oil usually remain in oil reservoirs after conventional water floods. A significant part of this remaining oil can still be economically recovered by Water- Alternating-Gas (WAG) injection. WAG injection involves drainage and imbibition processes taking place sequentially, hence the numerical simulation of the WAG process requires reliable knowledge of three-phase relative permeability (kr) accounting for cyclic hysteresis effects. In this study, the results of a series of unsteady-state two-phase displacements and WAG coreflood experiments were employed to investigate the behaviour of three-phase kr and hysteresis effects in the WAG process. The experiments were carried out on two different cores with different characteristics and wettability conditions, using a low IFT (interfacial tension) gas–oil system. The first part of this study, evaluates the current approach used in the oil industry for simulation of the WAG process, in which the two-phase relative permeability data are employed to generate three-phase kr values using correlations (e.g. Stone, Baker). The performance of each of the existing three-phase relative permeability models was assessed against the experimental data. The results showed that choosing inappropriate three-phase kr model in simulation of the WAG experiments can lead to large errors in prediction of fluid production and differential pressure. While some models perform better than others, all of the three-phase kr models examined in this study failed to adequately predict the fluid production behaviour observed in the experiments. The continued production of oil after the breakthrough of the gas, which was one of the features of gas and WAG injection experiments at low gas-oil IFT, was not captured with these models. The second aim of this research was to develop a method for obtaining the values of three-phase relative permeabilities directly from WAG core flood experiments. For this purpose, a new history matching method was devised based on a Genetic Algorithm to estimate three-phase kr from unsteady-state coreflood experiments. Based on this methodology, a three-phase coreflood optimizer was developed that generates best kr values by matching the experimentally obtained production and pressure data. First, the iii integrity of the developed software was successfully verified by using two sets of experimental three-phase kr data published in the literature. Then, the program was used to determine three-phase relative permeability of various cycles of the WAG experiments performed at different wettability conditions. Two key parameters affecting the WAG performance, including the hysteresis phenomena occurring between kr of the different WAG cycles and the impact of wettability of the rock, have been investigated. The data have been used to evaluate the existing hysteresis models published in the literature. Some of the shortcomings associated with the existing methods have been revealed and discussed. In the latter part of the thesis, a new methodology is proposed for modelling of threephase relative permeability for WAG injection. This approach addresses the hysteresis effects in the three-phase kr taking place during the WAG process and attempts to reduce the inadequacies observed in the existing models. The integrity of this technique has been validated against the three-phase kr data obtained from our WAG experiments.
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Xie, Kai, and 謝凱. "Volume quantification and visualization for spinal bone cement injection." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29807578.
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Lin, Chao-An. "Three-dimensional computations of injection into swirling cross-flow using second-moment closure." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280543.
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Kirk, Loren, Stacy D. Brown, and Paul Lewis. "Comparison of Stability Profiles of Three Generic Vancomycin Hcl for Injections Products." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/5284.
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Jacobs, Shawn. "Comparison of injection pain from the three mandibular block techniques and modulation by nitrous oxide." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63004.pdf.
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Wylonis, Edward M. (Edward Michael). "Production of injection molding tooling with conformal cooling channels using the three dimensional printing process." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/10727.
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Al-Honi, Mohamed Al-Arbi. "Three-dimensional physical model studies of air injection- in-situ combustion process : effect of reservoir heterogeneity." Thesis, University of Bath, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242786.
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Chuc, Alan, and Regina Miller. "A 12-Month Retrospective Analysis of Three Long-Acting Antipsychotic Injections in Patients with Schizophrenia: Comparison of Medication Adherence with Psychiatric Hospitalization Rates, Cost of Services, and Concomitant Medications." The University of Arizona, 2007. http://hdl.handle.net/10150/624325.
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Wallace, Michael Gary 1958. "A three-dimensional analysis of flow and solute transport resulting from deep well injection into faulted stratigraphic units." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277102.
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An analysis was performed of a Texas gulf coast hazardous waste injection well disposal system. The system was complicated by the presence of a fault which transected the injection interval. The existence of the fault presented the potential for enhanced vertical migration of the injected solutes via a tortuous path of interconnected, highly permeable sand units. Evaluation of this potential necessitated a fully three dimensional model which incorporated the arrangement of the alternating shales and sands and their associated discontinuities. Computer run time and memory limitations compelled a dissection of the problem into components, as well as the utilization of a specific mixture of conservative and realistic assumptions. The analysis indicated that within 10,000 years, the waste would advance vertically no further than one hundred feet into the overlying stratigraphy, and laterally no further than 24,000 feet from the point of injection.
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Pasquesoone, Gregory. "Controls for High Performance Three-Phase Switched Reluctance Motors." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1310874393.
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Al-Saghr, Abdulbaset Mohammed. "Three-dimensional physical model studies of air injection : in-situ combustion and downhole catalytic upgrading using horizontal wells." Thesis, University of Bath, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760710.
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Viera, Sotillo Juan Pablo. "Experimental study of the effect of nozzle geometry on the performance of direct-injection diesel sprays for three different fuels." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/81857.
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This thesis studies the influence of internal nozzle flow characteristics over a large spectrum of experimental conditions and diagnostics. Experiments were carried out for two nozzle geometries---cylindrical and conical single hole nozzles---and three different fuels. Two of the fuels are pure components---n-heptane and n-dodecane---while the third fuel consists of a three-component surrogate to better represent the physical and chemical properties of diesel fuel. Measurements include a complete hydraulic characterization consisting of instantaneous injection rate and spray momentum flux measurements; a high-speed visualization of isothermal liquid spray; a high-speed visualization of the evaporative inert spray, imaging liquid and vapor phases simultaneously and finally, a high-speed visualization of the high temperature reactive spray, imaging vapor phase and OH* chemiluminescence for each injection event. All high-temperature diagnostics were performed in a continuous flow test chamber that allows an accurate control on a wide range of thermodynamic conditions (up to 1000 K and 15 MPa).
The experimental findings from this work, and the large database obtained (available for download at: http://www.cmt.upv.es/DD01.aspx), could be used to validate CFD models that could help the community understand the fundamental driving mechanisms behind these observations.En esta tesis se estudia la influencia del flujo interno sobre un amplio espectro de condiciones y diagnósticos experimentales. Se realizaron experimentos para dos geometrías de tobera---toberas cilíndrica y cónica de un único orificio---y tres combustibles. Dos de los combustibles son puros---n-heptano y n-dodecano--- mientras el tercero es un combustible sustituto que consiste en una mezcla de tres componentes que busca representar mejor las propiedades físicas y químicas del diesel. Las medidas incluyen una caracterización hidráulica completa, compuesta por tasa de inyección y cantidad de movimiento instantáneas; una visualización de alta velocidad del chorro líquido isotermo; una visualización de alta velocidad del chorro inerte evaporativo, con captura simultánea de las fases líquida y vapor y, finalmente, una visualización del chorro reactivo a alta temperatura, con captura de la fase vapor y la quimioluminiscencia del radical OH* para cada evento de inyección. Todos los diagnósticos en condiciones de alta temperatura fueron realizados en una maqueta de alta presión y temperatura de flujo constante que permite controlar con precisión un rango amplio de condiciones termodinámicas (hasta 1000 K y 15 MPa). Los resultados experimentales y la gran base de datos obtenida en este trabajo (disponible en: http://www.cmt.upv.es/DD01.aspx), podrían ser utilizados para validar modelos CFD detallados que podrían ayudar a la comunidad científica a entender mejor los mecanismos fundamentales que producen los resultados observados.
Aquesta tesi estudia la influència del flux intern sobre un gran espectre de condicions i diagnòstics experimentals. Es van realitzar experiments per a dos geometries de tovera---toveres ci¿líndrica i cónica amb un únic orifici---i tres combustibles. Dos dels combustibles són purs---n-heptà i n-dodecà--- mentre el tercer combustible consisteix en una mescla de tres components que formen un combustible substitut que busca representar millor les propietats físiques i químiques del dièsel. Les mesures inclouen una caracterització hidràulica completa, composta per taxa d'injecció i quantitat de moviment instantanis; visualització d'alta velocitat del doll líquid isoterme; visualització d'alta velocitat del doll inert evaporatiu, capturant simultàniament les fases líquid i vapor i, finalment, una visualització del doll reactiu a alta temperatura, capturant la fase vapor i la quimioluminiscència del radical OH per a cada esdeveniment d'injecció. Tots els diagnòstics en condicions d'alta temperatura van ser realitzats en una insta¿lació d'alta pressió i temperatura amb flux constant que permet controlar amb precisió un ampli rang de condicions termodinàmiques (fins a 1000 K i 15 MPa). Els resultats experimentals i la gran base de dades obtinguda en aquest treball (disponible a la web en: http://www.cmt.upv.es/dd01.aspx), podrien ser utilitzats per tal de validar models CFD detallats que podrien ajudar a la comunitat científica a entendre millor els mecanismes fonamentals que produeixen aquestes observacions.
Viera Sotillo, JP. (2017). Experimental study of the effect of nozzle geometry on the performance of direct-injection diesel sprays for three different fuels [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/81857
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Strasser, Wayne Scott. "Seeking Understanding of Acoustics and Spray Character in a Three-Stream Pulsating Transonic Airblast Injector." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/77428.
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Despite the staggering volume of work in the open literature on primary and secondary atomization, there is nothing known that addresses the mechanisms for, and injector geometry implications for, primary atomization within a self-sustained pulsating transonic three-stream injector. Thus, a computational effort involving 86 simulations, including multiple validation exercises, has been executed in order to develop a numerical foundation and then study the effects of nozzle geometry, numerical methodology, grid resolution, modeled domain extent, feed rates, feed flow modulation, feed flow swirl, feed materials, and operating conditions. This is the first undertaking ever reported to disclose the intense details of transonic pulsating flows within the three-stream injector.
Metrics for assessment of acoustics and temporal spray character were numerous. Frequency responses among those metrics implied a common pulsation-driving mechanism. It has been discovered that liquid bridging with the production of a liquid fountain and shocklet-like structures in the retracted (pre-filming) zone, along with localized gas-liquid normal pressure gradients, are responsible for bulk pulsations. These findings were never reported in the literature, thus represent an important contribution of this study.
Unexpectedly, a new trend for temporal mean droplet size, when normalized by distance from the nozzle, versus distance from the nozzle has been found, which took a common form among all geometries and feed materials tested. Therefore, there is some value to simulate air-water flows, first, to scope general parameters and characteristics, before modeling more computationally challenging slurry flows. This represents an additional contribution of this work not previously reported in the literature.
Newly unveiled strong interactions between feed materials, geometry, and feed rate were discovered. Various combinations of inner nozzle retraction and slurry annular thickness were shown to be advantageous, depending on the goals of the injection system. The importance of either geometry variable for three-stream injectors has not been quantified until now.
The predictive power of various modeling frameworks has been assessed for the first time. Axi-symmetric (AS) simulations can successfully predict absolute acoustic details; remarkably and surprisingly, AS simulations can also be used for directional indicators of bulk droplet size. This is an especially powerful revelation given the massive reduction in computational requirements for AS models. Reduced order 3-D models are required for better droplet size estimates. A relatively simple eddy-viscosity turbulent model seems to be adequate for predicting droplet sizes for three-stream injectors, in which the primary energy source is bulk pulsations. For larger two-stream systems (atomization energy is sourced in local shear layer instability development), however, a state-of-the-art hybrid model (newly implemented for this effort) appeared to be necessary to capture the resulting droplet scales. Lastly, droplet size and characteristic flow length scale predictions for two open literature non-Newtonian liquid atomizers were made available.Ph. D.
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Reinhardt, Andreas [Verfasser], and Martin [Akademischer Betreuer] Maier. "Characterization of Rheology and Prediction of Three-dimensional Fiber Orientation during Injection Molding of Long Glass Fiber Reinforced Polypropylene / Andreas Reinhardt ; Betreuer: Martin Maier." Kaiserslautern : Technische Universität Kaiserslautern, 2019. http://d-nb.info/1185485260/34.
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Eismann, Ulrich. "A novel all-solid-state laser source for lithium atoms and three-body recombination in the unitary Bose gas." Paris 6, 2012. http://www.theses.fr/2012PA060078.
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Dans cette thèse, nous présentons des nouvelles techniques et leur application dans l’étude des gaz d’atomes de lithium ultrafroids. Dans la première partie de cette thèse, nous présentons le développement d’une nouvelle source laser de faible largeur spectrale, capable d’émettre 840 mW de puissance dans la gamme des longeurs d’ondes des raies D du lithium atomique à 671 nm. La source est basée sur un laser en anneau pompé par diode, fonctionnant sur la transition à 1342 nm dans le Nd:YVO, capable de produire 1. 3 W de lumière monomode dans un faisceau limité par la diffraction. Le faisceau de sortie est ensuite doublé en fréquence dans un cristal de phosphate de potassium titanyl (ppKTP) périodiquement polarisé dans une cavité externe. Nous obtenons un rendement du doublage de 86%. Une accordabilité de la fréquence de sortie sur plus de 400 GHz et le verrouillage de l’ensemble des cavités par rapport aux raies D du lithium sont accomplis. Nous avons mesuré la largeur de raie d’émission à 200+400-200kHz. Dans la deuxième partie de cette thèse, nous employons la source sur un dispositif expérimental pour refroidir et piéger des atomes de lithium. Nous réalisons des echantillons du gaz de Bose unitaire à température finie au voisinage d’une résonance de Fano-Feshbach, où les interactions entre les atomes sont maximales. Nous présentons des mesures du taux de pertes à trois corps en fonction de la température. Les pertes mésurées atteignent la valeur limite imposée par la mécanique quantique sans aucun paramètre ajustable. Cette mesure permet l’introduction d’un critère de quasi-équilibre. Dans ce régime, en utilisant une technique basée sur l’imagerie in-situ développée dans notre groupe, nous fournissons une première mesure de l’équation d’état du gaz de Bose unitaire à basse fugacitéIn this thesis we present novel techniques for the study of ultracold gases of lithium atoms. In the first part of this thesis, we present the development of a narrow-linewidth laser source emitting 840mW of output power in the vicinity of the lithium D-line resonances at 671 nm. The source is based on a diode-end-pumped unidirectional ring laser operating on the 1342-nm transition in Nd:YVO4, capable of producing 1. 3W of single-mode light delivered in a diffraction-limited beam. The output beam is subsequently frequency-doubled using periodically-poled potassium titanyl phosphate (ppKTP) in an external buildup cavity. We obtain doubling efficiencies of up to 86%. Tunability of the output frequency over more than 400GHz and frequency-locking of the cavity ensemble with respect to the lithium D-line transitions are accomplished. We measure the linewidth to be 200+400-200kHz. In the second part of this thesis, we employ the source in an experimental setup to produce to cool and trap lithium atoms. We realize samples of finite-temperature unitary Bose gases around the center of a Fano-Feshbach resonance, where interactions between the atoms are maximized. We present temperature-dependent measurements of the unitarity-limited three-body loss rate. The measured losses attain the limiting value imposed by quantum mechanics without adjustable parameters. This measurement allows for the introduction of a criterion for quasi-equilibrium. In this regime, by using technique based on in-situ imaging developed in our group, we provide a first measurement of the equation of state of the unitary Bose gas at low fugacities
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Singh, Bhanu Pratap. "Real-time detection of stator resistance unbalances in three phase drives." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286813.
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An estimated 30% of the faults in Induction Machine (IM) are related to its stator. These faults are mostly in the form of an Inter-Turn Short Circuit (ITSC) fault i.e., when two winding inside the stator of IM are shorted due to insulation failure. However, ITSC fault can be avoided by detecting them in advance and then scheduling the maintenance of the IM. This thesis studies two methods for detecting this incipient ITSC fault in a three-phase IM and then estimating the stator resistance unbalance due to the ITSC fault. The first method is based on the asymmetry caused in the IM by the ITSC fault. As a result of this asymmetry, the negative sequence components of the stator voltages and the stator currents are generated inside the IM. A healthy IM also have these negative sequence components due to the manufacturing process and the supply voltage unbalances. The characteristics and the compensation methods of these negative sequence components in a healthy IM are discussed. The results show that after compensating the negative sequence components in a healthy machine, they can be used for detecting an ITSC fault and then to calculate the fault quantities as well as the stator resistance unbalances. The second method for detecting an ITSC fault is based on analysing the stator resistance unbalances. A three-phase drive is used to inject DC voltage in the stationary reference frame. The DC current generated by this DC voltage is measured and then by applying Ohm’s law stator phase resistances are calculated. In a healthy IM, the phase resistances are balanced. However, in case of ITSC fault in any of the phases, the phase resistance of that phase deviates from those of the other two phases which can be utilized for detecting ITSC fault.Uppskattningsvis 30% av alla fel i induktionsmaskiner (IM) är kopplad till dess stator. Dessa fel är i huvudsak Inter-Turn Short Circuit (ITSC)-fel, dvs. två lindningar inom IM:ens stator blir kortsluta pga. ett isoleringsfel. Emellertid kan man undvika ITSC-fel genom att detektera dem i förhand och planera underhåll. Det här examensarbetet undersöker två metoder för att detektera ett förestående ITSC-fel i en tre-fas IM. Den första metoden är baserad på asymmetrin i IM:er pga. ITSC-felet. Resultatet av den här asymmetrin är att en negativ sekvens genereras i IM:ens statorspänning och statorström. En oskadad IM kan också visa dessa negativa sekvenser pga. tillverksprocessen och statorspänningsobalanser. Egenskaperna och kompensationsmetoderna för dessa negativa sekvenser i en oskadad IM kommer att diskuteras. Resultaten visar att efter kompenseringen av de negativa sekvenserna i en oskadad IM, kan de användas för att detektera ITSC-fel och efteråt för att beräkna felstorheter och även statormotståndobalanser. Den andra metoden för att detektera ITSC-fel är baserad på en undersökning av statormotståndobalanser. Ett tre-fas-drivsystem används för att injektera likspänning i den stationära referensramen. Likströmmen som följer av denna likspänning mäts och statorfasmotstånden beräkna efteråt med Ohms lag. I en oskadad IM är fasmotstånden balanserade. Däremot, när ett ITSC-fel uppstår i en fas, avviker fasmotståndet i den felaktiga fasen från de andra två fasernas, vilket kan användas för att detektera ITSC-fel.
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Starigazda, Michal. "Optimalizace testování pomocí algoritmů prohledávání prostoru." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-234928.
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Testing of multi-threaded programs is a demanding work due to the many possible thread interleavings one should examine. The noise injection technique helps to increase the number of tested thread interleavings by noise injection to suitable program locations. This work optimizes meta-heuristics search techniques in the testing of concurrent programs by utilizing deterministic heuristic in the application of genetic algorithms in a space of legal program locations suitable for the noise injection. In this work, several novel deterministic noise injection heuristics without dependency on the random number generator are proposed in contrary to the most of currently used heuristic. The elimination of the randomness should make the search process more informed and provide better, more optimal, solutions thanks to increased stability in the results provided by novel heuristics. Finally, a benchmark of programs, used for the evaluation of novel noise injection heuristics is presented.
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Абдулкеримов, Илимдар Диляверович. "Технологическое обеспечение качества резьбовых соединений в глухих отверстиях деталей из алюминиевых сплавов деформирующим инструментом." Thesis, НТУ "ХПІ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/20297.
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Диссертация на соискание учёной степени кандидата технических наук по специальности 05.02.08 – технология машиностроения. Национальный технический университет "Харьковский политехнический институт", Харьков, 2016.
Диссертация посвящена решению научно-технической задачи технологического обеспечения герметичности резьбовых соединений деталей из алюминиевых сплавов с газо-усадочной пористостью деформирующим инструментом. В работе проведен анализ существующих систем обработки глухих отверстий в алюминиевых сплавах из газо-усадочных материалов, выявлены основные факторы, определяющие качество и производительность процесса обработки отверстий. Показано, что для таких процессов как обеспечение необходимых эксплуатационных характеристик соединений нужно управлять параметрами состояния поверхностного слоя в процессе их изготовления, а также уметь рассчитывать их на стадии проектирования технологического процесса. Показано исследование технологических свойств алюминиевого сплава АК12М2, полученного литьем под давлением, а именно проведено моделирование ППД литейного алюминиевого сплава АК12М2, а также сравнение свойств поверхности до и после ППД и влияние угла деформации с учетом количества циклов ППД на качество поверхности. Результаты проведенных исследований позволили дать практические рекомендации по внедрению результатов работы на ОАО "Пневматика" (г. Симферополь), а именно показана обработка на примере детали корпус крана ПКР25 и получены герметичные разъемных соединения в деталях из алюминиевых сплавов с газо-усадочной пористостью. Проведено сравнение качества резьбовых соединений, получаемых по базовому и новому варианту обработки и оценка экономической эффективности. Это позволило снизить технологическую себестоимость и получить экономический эффект в размере 18207 грн., за счёт снижения трудоёмкости обработки, затрат на инструмент и технологические жидкости.The thesis for the degree of candidate of technical sciences, specialty 05.02.08 - technology of mechanical engineering. National Technical University "Kharkiv Polytechnic Institute", Kharkov, 2016. The dissertation is devoted to the processing to ensure the tightness of threaded connections of details from aluminum alloys deformed gas shrinkage porosity tool. Analytical and experimental research method of machining of the threaded holes in applying deforming tools based modeling of the process of forming a trumpet groove in blind holes deforming tool. Theoretically grounded possibility of the surface layer of quality blind holes after PPD alloy AK12M2. The new design tools and practical advice on selecting treatment regimes that ensure maximum processing efficiency deaf threaded holes. The economic effect of the introduction of the main provisions of the production of 18,207.44 UA.
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Zhong, Shan. "Measurement calibration/tuning & topology processing in power system state estimation." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1595.
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State estimation plays an important role in modern power systems. The errors in the telemetered measurements and the connectivity information of the network will greatly contaminate the estimated system state. This dissertation provides solutions to suppress the influences of these errors.
A two-stage state estimation algorithm has been utilized in topology error identification in the past decade. Chapter II discusses the implementation of this algorithm. A concise substation model is defined for this purpose. A friendly user interface that incorporates the two-stage algorithm into the conventional state estimator is developed.
The performances of the two-stage state estimation algorithms rely on accurate determination of suspect substations. A comprehensive identification procedure is described in chapter III. In order to evaluate the proposed procedure, a topology error library is created. Several identification methods are comparatively tested using this library.
A remote measurement calibration method is presented in chapter IV. The un-calibrated quantities can be related to the true values by the characteristic functions. The conventional state estimation algorithm is modified to include the parameters of these functions. Hence they can be estimated along with the system state variables and used to calibrate the measurements. The measurements taken at different time instants are utilized to minimize the influence of the random errors.
A method for auto tuning of measurement weights in state estimation is described in chapter V. Two alternative ways to estimate the measurement random error variances are discussed. They are both tested on simulation data generated based on IEEE systems. Their performances are compared. A comprehensive solution, which contains an initialization process and a recursively updating process, is presented.
Chapter VI investigates the errors introduced in the positive sequence state estimation due to the usual assumptions of having fully balanced bus loads/generations and continuously transposed transmission lines. Several tests are conducted using different assumptions regarding the availability of single and multi-phase measurements. It is demonstrated that incomplete metering of three-phase system quantities may lead to significant errors in the positive sequence state estimates for certain cases. A novel sequence domain three-phase state estimation algorithm is proposed to solve this problem.
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Абдулкерімов, Ілімдар Діляверович. "Технологічне забезпечення якості різьбових з'єднань у глухих отворах деталей з алюмінієвих сплавів деформуючим інструментом." Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/20295.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.02.08 – технологія машинобудування. Національний технічний університет "Харківський політехнічний інститут", Харків, 2016.
Дисертація присвячена вирішенню проблеми технологічного забезпечення герметичності різьбових з'єднань деталей з алюмінієвих сплавів з газо-усадковою пористістю деформуючим інструментом. У роботі проведено аналіз існуючих систем обробки глухих отворів у деталях з газо-усадкових матеріалів. Проведено аналітичне та експериментальне дослідження методу механічної обробки різьбових отворів при застосуванні деформуючого інструменту з урахуванням моделювання процесу формоутворення трубних різьб у глухих отворах деформуючим інструментом. Розроблено конструктивні й технологічні параметри деформуючого інструменту для глухих отворів під трубну різьбу в деталях з алюмінієвих сплавів з газо-усадковою пористістю. Теоретично обґрунтовано можливість забезпечення якісного поверхневого шару глухих отворів після ППД сплаву АК12М2. Запропоновано нові конструкції інструменту та практичні рекомендації щодо вибору режимів обробки, що забезпечують високу ефективність обробки глухих різьбових отворів. Економічний ефект від упровадження основних положень роботи у виробництво становить 18207 грн.The thesis for the degree of candidate of technical sciences, specialty 05.02.08 - technology of mechanical engineering. National Technical University "Kharkiv Polytechnic Institute", Kharkov, 2016. The dissertation is devoted to the processing to ensure the tightness of threaded connections of details from aluminum alloys deformed gas shrinkage porosity tool. Analytical and experimental research method of machining of the threaded holes in applying deforming tools based modeling of the process of forming a trumpet groove in blind holes deforming tool. Theoretically grounded possibility of the surface layer of quality blind holes after PPD alloy AK12M2. The new design tools and practical advice on selecting treatment regimes that ensure maximum processing efficiency deaf threaded holes. The economic effect of the introduction of the main provisions of the production of 18,207.44 UA.
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Loureiro, Pedro da Cruz. "Controle de tensão e harmônicos por compensador estático de reativos com ajuste de parâmetros via redes neurais artificiais." Universidade Federal de Juiz de Fora, 2012. https://repositorio.ufjf.br/jspui/handle/ufjf/1785.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Neste trabalho é proposta a aplicação de redes neurais artificiais para ajuste de parâmetros de um compensador estático de reativos, para controle de tensão e harmônicos. Devido à intensa produção de correntes harmônicas e possíveis afundamentos de tensão em instalações industriais como o forno a arco, é necessário um sistema de controle eficiente e robusto. Além disso, os sistemas elétricos de potência se encontram em um cenário com a presença cada vez maior de geração distribuída, cargas não-lineares e forte tendência à operação no contexto das smartgrids e microgrids. Sendo assim, o suporte de reativos deve ser adequado a esses sistemas, podendo atuar de forma rápida, precisa e confiável. Uma possível solução é a utilização de um compensador estático de reativos (CER) com função adicional de filtragem no ponto onde se deseja controlar a tensão e a distorção harmônica. Entretanto, para o correto funcionamento, é necessário um sistema preciso para o ajuste dos parâmetros do CER, ou seja, determinar os ângulos de disparo dos tiristores e o número de bancos de capacitores a serem ligados. Neste trabalho é proposta uma estratégia de controle via redes neurais artificiais, treinadas para o reconhecimento de padrões de operação em regime permanente e definição da configuração do CER, conferindo inteligência ao equipamento. Os desenvolvimentos propostos foram implementados no ambiente MatLab®. A validação do método é feita através de simulações em sistemas-teste, presentes na literatura técnica, utilizando o fluxo de potência pelo método de injeção de correntes trifásico harmônico. Os resultados obtidos mostram as vantagens da utilização da estratégia proposta.
In this work, an artificial neural network-based static var compensator tuning is proposed for voltage and harmonic distortion control. Due to intense harmonic current injection and possible voltage sags produced by industrial facilities such as arc furnaces, an efficient robust control system is needed. Besides, electrical power systems face a new scenario with high penetration of distributed generation and non-linear loads and increased smart grid and microgrid trends. Therefore, the available reactive power sources must be able to provide system control in order to operate the system in a fast, accurate and reliable way. The application of a static var compensator (SVC) with additional filtering function at the controlled node is a possible solution. However, a precise SVC parameters tuning is needed, in order to make the system to work properly. In this work, a control strategy based on artificial neural networks is proposed. The neural networks are trained to recognize steadystate operating patterns and give the SVC adjustment. The proposed technique was implemented in the MatLab® environment. The methodology is validated by simulations in test-systems available in technical literature, using the three-phase harmonic current injection method power flow. Results show the advantages of the proposed methodology.
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Bilha, Vitor Meira. "Análise do processo de retificação interna aplicado à fabricação de bicos injetores diesel." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1889.
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A utilização mais eficiente dos recursos naturais tem levado a indústria a aumentar a eficiência dos produtos manufaturados. Veículos de transporte Diesel estão incluídos neste cenário. Nos motores Diesel, um componente importante do sistema de injeção é o bico injetor. Uma legislação recente no Brasil introduziu limites de emissões EURO5. Estes novos parâmetros tiveram impacto no projeto do bico injetor com tolerâncias sendo reduzidas, em especial na área da sede do corpo do bico injetor, alterando o parâmetro funcional de pressão de abertura do produto. Neste cenário, o impacto desta superfície cônica retificada sobre a pressão de abertura é grande, bem como, sobre o desempenho do motor Diesel. Este estudo tem como objetivo analisar o defeito de topografia superficial típico e recorrente no processo de retificação interna cônica da sede do corpo dos bicos injetores. Um experimento planejado foi realizado de acordo com método Taguchi e determinou-se a relação sinal-ruído para dois parâmetros de topografia 2D. A superfície da sede também foi analisada utilizando análise topográfica 3D. Os resultados deste estudo incluem a indicação de possíveis causas do defeito recorrente, caracterização dos principais elementos do processo de retificação, caracterização da superfície retificada e otimização dos parâmetros do processo de retificação.Industries of manufactured products have increased their efficiency optimizing the natural resources usage and Diesel commercial vehicles are included in this scenario. For Diesel engines, one of the most important components of the injection system is the nozzle injector. In Brazil, EURO5 legislation was recently introduced, bringing new emission limits for Diesel engines. Because of this, the nozzle injector design has changed and some manufacturing tolerances were reduced, in special the body seat geometry. This also changed the nozzle opening pressure. In this new process, the body seat grinded conical surface impacts on this functional parameter and consequently the Diesel engine performance. This study has as target to analyze a recurrent defect in the internal conic grinding process of the nozzle body seat. A trial was performed in this process according to Taguchi method and signal / noise ratio for 2D topographic parameters were defined. The body seat surface was also analyzed using 3D topographic analysis. The results of this study include the possible cause of the recurrent failure, characterization of the ground surface, process main elements integrity assessment and optimization of the grinding process parameters.
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Abreu, Eduardo Cardoso de. "Modelagem e simulação computacional de escoamentos trifásicos em reservatórios de petróleo heterogêneos." Universidade do Estado do Rio de Janeiro, 2007. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=765.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorNeste trabalho é apresentado um novo método acurado com passo de tempo fracionário, baseado em uma técnica de decomposição de operadores, para a solução numérica de um sistema governante de equações diferenciais parciais que modela escoamento trifásico água-gás-óleo imiscível em reservatórios de petróleo heterogêneos no qual os efeitos de compressibilidade do gás não foram levados em conta. A técnica de decomposição de operadores em dois níveis permite o uso de passos de tempo distintos para os três problemas definidos pelo procedimento de decomposição: convecção, difusão e pressão-velocidade. Um sistema hiperbólico de leis de conservação que modela o transporte convectivo das fases fluidas é aproximado por um esquema central de diferenças finitas explícito, conservativo, não oscilatório e de segunda ordem. Este esquema é combinado com elementos finitos mistos, localmente conservativos, para a aproximação numérica dos sistemas de equações parabólico e elíptico associados aos problemas de transporte difusivo e de pressão-velocidade, respectivamente. O operador temporal associado ao sistema parabólico é resolvido fazendo-se uso de uma estratégia implícita de solução (Backward Euler). O modelo matemático para escoamento trifásico considerado neste trabalho leva em conta as forças de capilaridade e expressões gerais para as funções de permeabilidade relativa, campos variáveis de porosidade e de permeabilidade e os efeitos da gravidade. A escolha de expressões gerais para as funções de permeabilidade relativa pode levar à perda de hiperbolicidade escrita e, desta maneira, à existência de uma região elíptica ou de pontos umbílicos para o sistema não linear de leis de conservação hiperbólicas que descreve o transporte convectivo das fases fluidas. Como consequência, a perda de hiperbolicidade pode levar à existência de choques não clássicos (também chamados de choques transicionais ou choques subcompressivos) nas soluções de escoamentos trifásicos. O novo procedimento numérico foi usado para investigar a existência e a estabilidade de choques não clássicos, com respeito ao fenômeno de fingering viscoso, em problemas de escoamentos trifásicos bidimensionais em reservatórios heterogêneos, estendendo deste modo resultados disponíveis na literatura para problemas de escoamentos trifásicos unidimensionais. Experimentos numéricos, incluindo o estudo de estratégias de injeção alternada de água e gás (Water-Alternating-Gas (WAG)), indicam que o novo procedimento numérico proposto conduz com eficiência computacional a resultados numéricos com precisão. Perspectivas para trabalhos de pesquisa futuros são também discutidas, tomando como base os desenvolvimentos reportados nesta tese.
We present a new, accurate fractional time-step method based on an operator splitting technique for the numerical solution of a system of partial differential equations modeling three-phase immiscible water-gas-oil flow problems in heterogeneous petroleum reservoirs in which the compressibility effects of the gas was not take into account. A two-level operator splitting technique allows for the use of distinct time steps for the three problems defined by the splitting procedure: convection, diffusion and pressure-velocity. A system of hyperbolic conservation laws modelling the convective transport of the fluid phases is approximated by a high resolution, nonoscillatory, second-order, conservative central difference scheme in the convection step. This scheme is combined with locally conservative mixed finite elements for the numerical solution of the parabolic and elliptic problems associated with the diffusive transport of fluid phases and the pressure-velocity problem, respectively. The time discretization of the parabolic problem is performed by means of the implicit backward Euler method. The mathematical model for the three-phase flow considered in this work takes into account capillary forces and general expressions for the relative permeability functions, variable porosity and permeability fields, and the effect of gravity. The choice of general expressions for the relative permeability functions may lead to the loss of strict hyperbolicity and, therefore, to the existence of an elliptic region of umbilic points for the systems of nonlinear hyperbolic conservation laws describing the convective transport of the fluid phases. As a consequence, the loss of hyperbolicity may lead to the existence of nonclassical shocks (also called transitional shocks or undercompressive shocks) in three-phase flow solutions. The numerical procedure was used in an investigation of the existence and stability of nonclassical shocks with respect to viscous fingering in heterogeneous two-dimensional flows, thereby extending previous results for one-dimensional three-phase flow available in the literature. Numerical experiments, including the study of Water-Alternating-Gas (WAG) injection strategies, indicate that the proposed new numerical procedure leads to computational efficiency and accurate numerical results. Directions for further research are also discussed, based on the developments reported in this thesis.
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Loreti, Ludovico. "Pass The Hash attack. Panoramica, sperimentazione ed analisi." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/17297/.
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La tesi è incentrata sul noto attacco informatico Pass The Hash e sul suo sviluppo all'interno di un sistema Microsoft Active Directory. Viene descritta una panoramica dell'attacco accennando la sua storia ed evoluzione fino ad oggi, alcuni dei tanti attacchi informatici ad esso propedeutici ed un background tecnico in cui vengono spiegate le sue componenti principali: il tool che viene utilizzato oggigiorno per sperimentare questa tecnica (Mimikatz), le funzioni di hash, i sistemi Single Sign-On, la suddivisione in domini, alberi e foreste di Active Directory.
In seguito viene mostrato l'ambiente di test in cui l'attacco è stato sperimentato, specificando i software ed i computer utilizzati.
L'ultima parte della tesi è incentrata sulla realizzazione dell'attacco informatico in modo sperimentale in quanto l'attacco teoricamente si ferma alla versione di Windows 8 e Windows Server 2012. Qui è realizzato su sistemi aventi Windows 10 e Windows Server 2016 aggiornati al momento in cui si scrive.
Nel capitolo conclusivo vengono ripresi i punti salienti dell'attacco realizzato poc'anzi e vengono descritte alcune tecniche pensate ad hoc per la mitigazione del Pass The Hash.
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李清貴. "Injection Moulding of a Plastic Bottle Cap with Inner Screw Thread." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/07168899045661265253.
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碩士國立中興大學
機械工程學系
87
ABSTRACT The technique of formation and unscrewing of a bottle cap with inner-thread in an injection mold is studied. The shrinkage of the bottle cap from injection molding with various packing pressures, mold and melting temperatures is analyzed. Two plastic materials, low density polyethylene (LDPE) and polypropylene (PP), are used in tests. Three plastics melting temperatures, 205℃,220℃ and 235℃, are considered. The minimum and maximum effective injection pressures and velocities are obtained and the results are represented on a P-V diagram. The optimum operating range is indicated. In the shrinkage analysis, the mold temperature individually is controlled at 30℃,45℃ and 60℃.The packing pressure is in the range 810 kg/cm2 to 1160 kg/cm2. The effects of pitch and screw thread depth on height, wall thickness, inner and outer diameters of the cap are investigated for various packing pressures, mold and melting temperatures. The measured shrinkage data of cap inner diameter and thickness are individually correlated in a polynomial equation. Four conventional devices for unscrewing of bottle cap in inner-thread die are discussed. The mold used in experiment is equipped with a chain-to-chain wheel unscrewing mechanism. keywords : melting temperature, shrinkage, injection mold, polyethylene, polypropylene。
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Grossman, Igor. "Applications of multi-threading paradigms to stimulate turbulent flows." Thesis, 2017. https://vuir.vu.edu.au/40454/.
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Flow structures in turbulent flows span many orders of magnitude of length and time scales. They range from the length scale at which very small eddies lose their coherence as their translational kinetic energy is dissipated into heat, up to eddies the size of which is related to that of the macroscopic system. The behaviour of the range of flow structures can be captured by assuming that the fluid is a continuum, and they can be described by solving the Navier-Stokes equations. However, analytical solutions of the Navier-Stokes equations exist only for simple cases.
A complete description of turbulent flow in which the flow variables velocity and pressure are resolved as a function of space and time can be obtained only numerically. The instantaneous range of scales in turbulent flows increases rapidly with the Reynolds number. As a result, most engineering problems have a wide range of scales that can be computed using direct numerical simulation (DNS). As the complexity of the calculated flows increases, an improvement in turbulence models is often needed. One way to overcome this problem is to search for models that better capture the features of turbulence.
Furthermore, the models should be parameterised in a way that allows flows to be simulated under a wide range of conditions. DNS is a useful tool in this endeavour, and it can be used to complement the long-established methodologies of experimental research. A large number of computational grids must be used to simulate a high Reynolds number inflows that occur in the complicated geometries often encountered in practical applications. This approach requires a considerable amount of computational power. For example, reducing the grid spacing in half increases the computational cost by a factor of about sixteen.
Challenges presented by limitations imposed by computer hardware significantly limit the number of practical numerical solutions required to satisfy engineering needs.
In this work, we propose an alternative approach. Rather than running an application that solves the Navier-Stokes equations on one computer, we have developed a platform that allows a group of computers to communicate with one another working together to obtain a solution of a specific flow problem.
This approach helps to overcome the problem of hardware limitations. However, to grasp these challenges, we must devise new strategies to computational paradigms associated with parallel computing. In the case of solving the Navier-Stokes equations, we have to deal with significant computational and memory requirements. To overcome these requirements, software should be able to be run on many high-performance computers simultaneously, and network communication may become a new limiting issue that is specific only to parallel environments. Translating to parallel environments triggers several scenarios that do not exist when developing software that executes sequential operations. For example, "racing conditions" may appear that result in many threads that attempt to use different values of a shared variable, or they simultaneously attempt to overwrite it. The order of executions may be random as the operating system can swap between the threads at any time. Attempts to synchronise the threads may result in "deadlock" when all resources become simultaneously locked. Debugging and problem-solving in parallel environments is quite often difficult due to the potentially random nature of the orders in which threads run. All of these features require the development of new paradigms, and we must transform our way of envisioning the development of software for parallel execution. The solution to this problem is the motivation for the work presented in this thesis.
A significant contribution of this work is to strategically use the ideas of thread injection to speed up the execution of sequential code. Bottlenecks are identified, and thread injection is used to parallelise the code that may be distributed to many different systems. This approach is implemented by creating a class that takes control over the sequential instructions that create the bottlenecks. The challenge to engineers and scientists is to determine how a given task can be split into components that can be run in parallel. The method is illustrated by applying it to Channelflow (Gibson, 2014), which is open-source Direct Numerical Simulation software used to simulate flows between two parallel plates.
Another challenge that arises when approaching representations of real geometries is the scale and magnitude of the data samples. For example, Johns Hopkins Turbulent Database (JHTB) contains results of the solution of direct numerical simulation (DNS) of isotropic turbulent flow in the incompressible fluid in 3D space and only requires 100 TB data. Much more data needed to perform a simulation, and this is just a straightforward model.
A natural answer to this challenge is to exploit the opportunities offered by contemporary applications of ‘database technology’ in computational fluid dynamics (CFD) and turbulence research. Direct numerical solution of the Navier-Stokes equations resolves all of the flow structures that influence turbulent flows. Still, in the case of Large Eddy Simulation, the Navier-Stokes equations are spatially filtered so that they are expressed in terms of the velocities of larger-scale structures. The rate of viscous dissipation is quantified by modelling the shear stress, and this process can lead to inaccuracies. A means of rapid testing and evaluation of models is therefore required, and this involves working with large data sets.
The contribution of this work is the development of a computational platform that allows LES models to be dynamically loaded and to be rapidly evaluated against DNS data. An idea permeating the methodology is that a core is defined that contains the ‘know-how’ associated with accessing and manipulating data, and which operates independently of a plug-in. The thesis presents an example that demonstrates how users can examine the accuracy of LES models and obtain results almost instantaneously. Such methods allow engineers or scientists to propose their own LES models and implement them as a plug- in with only a few lines of code. We have demonstrated how it can be done by converting the Smagorinsky model to a plug-in to be used on our platform.
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Wang, Bo-Huan, and 王博煥. "Current Injection Based Three Phase Optimal Power Flow." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/s29v59.
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碩士國立臺灣海洋大學
電機工程學系
102
In recent years there has been a tendency toward liberalization of power industry. For this reason, independent system operators in various countries have an urgent need for real-time simulation analysis software featuring system safety and economic operation .OPF ,one of the major analysis simulation tools. In the past power flow is used with three phase balance, but the system in parallel with an increasing number of large single-phase loads, or the user of each phase unbalanced load, among other factors, cause all of its system imbalance. In addition, smart grid technologies become more sophisticated, the control system equipment is also more flexible, the future may also be controlled with the device (for example, the capacitance of each phase injection control) to improve the safe operation of the system. Therefore, this thesis intends to develop a set of analytical tools for unbalanced transmission system. As in the general transmission system can through economic dispatch and power factor to determine the output of the generator, therefore this three-phase power flow program does not have a PV-BUS, by the generator as PQ-BUS, this thesis proposes a three-phase synchronous generator motor model. This thesis presents the model of three-phase power system components can reasonably analytical characteristics of the three-phase system components, such as three-phase synchronous generator, three-phase transformers, transmission lines, shunt capacitors and load, as well as considering the internal impedance of the generator, voltage unbalance at the generator terminal, copper losses and iron losses in the transformer, transformer phase shift and other issues, and lists nine different transformer wiring, in order to meet the demand of the three-phase analysis and the algorithm proposed in this thesis is based on Equivalent-Current-Injection, and then to find a Taylor expansion set of linear equations, and using linear programming to solve the set of linear equations, and can find the same solution.
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Lung, Su-Tz, and 蘇子龍. "Harmonic Injection Method for Single-Switch Three-Phase Boost Rectifier." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/72052520649551461900.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
91
The single-switch three-phase boost rectifier is an attractive solution because of its simplicity, relatively good performance and high efficiency. However the single-switch three-phase boost rectifier can not be pushed to high power levels due to the fifth harmonics of the input current. An approach employing harmonics injection is proposed to reduce the fifth harmonics to meet the IEC61000-3-2 class A requirement without significantly increasing the rectifier voltage output. In this thesis, the injection principle is analyzed firstly. Then, the relationships of the maximum rectifier input power and voltage gain with different harmonics injection are developed. At least, experimental results are performed to prove the proposed scheme.
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Chang, Wen-Ya, and 張汶雅. "A Three Dimensional CAE Analysis of Injection-Compression Molding Process." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/79822577229947972452.
Full textAbstract:
碩士國立清華大學
化學工程學系
88
In this paper, a numerical algorithm is developed to simulate the injection compression molding process. By using viscoelastic theory as describing P-V-T behavior of polymer material, and by using modified cross model as describing rheological behavior of polymer material, we can build up a complete formulation. By employing finite volume method, the governing equations are solved. We calculate 3-D velocity field and pressure field and thermal field by iterative solver. Combining formulation and numerical method ,a simulation program is got to predict the distribution of pressure, temperature, density and velocity during the injection compression process. Based on these simulation results, it was found suitable for the physical phenomena ,and it was found that the quality of product is well improved by this technology.
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Chen, Yu-Sheng, and 陳昱升. "Wideband Voltage-Controlled Oscillator and Divide-by-Three Injection-Locked Frequency Divider." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/96487687201659753436.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
98
The voltage-controlled oscillator (VCO) and the frequency divider are main blocks of a frequency synthesizer’s. Bandwidth of a frequency synthesizer is dominated by operating frequency ranges of these two blocks, so we require wideband VCOs and frequency dividers for wideband applications. A good VCO must exhibit low-phase-noise characteristic to prevent noise in adjacent frequencies from being down-converted or up-converted. We generally apply an injection-locked frequency divider (ILFD) to perform frequency division at high frequency. The wider the locking range is, the better ILFD. We present a voltage-controlled oscillator and an injection-locked frequency divider in this thesis. The former is a VCO with 33 % frequency tuning range and is fabricated in UMC 90 nm process. The latter is a divide-by-three ILFD with 16.5 % locking range and 35 % operation range. This ILFD is implemented in TSMC 0.13 process. Both of the proposed circuits are low-power as the power consumption of the VCO and the ILFD are 1.32 mW and 2.05 mW respectively. At first, we present a wide-tuning-range VCO, which adopts stacked inductors to straighten out the absence of ultra-thick top metal in the standard digital process. Thus, the phase noise is lowered. Meanwhile, transistors with low threshold voltage and varactors with optimized tuning ratio are used to acquire a wide tuning range and low process variation. At the supply voltage 0.4 V, the tuning range is 3.62 GHz, ranging from 9.15 GHz to 12.77 GHz. Phase noise at 1 MHz offset frequency from the carrier frequency 10.13 GHz is -108.78 dBc/Hz. Figure of merit (FOM) and the figure of merit with tuning range (FOMT) are -187.68 dBc/Hz and -198.06 dBc/Hz respectively. Then, a wide-locking-range divide-by-three ILFD is presented. Its input transistors act as linearly mixing transistors. A signal, of which the frequency is twice that of the free-running signal, is extracted by the circuit itself. This signal is mixed into the input of the ILFD to solve the problem that the subharmonic is too weak in conventional structure. This results in a wider locking range. At the supply voltage of 1.3 V, the power consumption is 2.05 mW. At Vtune of 1.3 V, the locking range is from 14.5 GHz to 17.1 GHz. The operation range is from 12.0 GHz to 17.1 GHz, while Vtune varies from 0 V to 1.3 V. Percentage of the locking range and the operation range are 16.5 % and 35.1 % respectively.
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Araújo, Billy Jácome de. "Integrated three-dimensional flow and thermal simulation of the injection moulding process." Doctoral thesis, 2009. http://hdl.handle.net/1822/9941.
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Tese de doutoramento em Engenharia Mecânica (área do conhecimento em Mecânica dos Fluídos e Transferência do Calor)The injection moulding process is widely used for the production of plastic parts. To optimize part quality and design while reducing cost in a systematic manner can be achieved by employing injection moulding simulation during the design phase. Furthermore, the solution of problems using a trial and error approach at the end of the production phase may affect negatively both cost of the mould and delivery time. The use of accurate injection moulding simulation tools allow the mould-maker to add value to their clients and is an important step towards o offering integrated part and mould design solutions. In the present work, a parallel flow solver was developed to simulate the injection moulding process. The algorithm solves the three-dimensional Navier-Stokes equation on unstructured meshes using a segregated approach. The position of the melt-front was captured using the VOF method and the temperature was computed using a scalar transport equation. Two numerical methods were used to discretise the set of partial differential equations: finite element method and finite volume method. The numerical methods were tested for a variety of cases and results were compared with analytical and experimental solutions when possible. The solver was tested running up to 80 processors in parallel and the results show good scalability without the loss of precision. The proposed model presents good stability, accuracy and efficiency in the simulation of the non-isothermal flow of viscous fluids in complex three-dimensional domains.
A moldação por injecção é um processo bastante utilizado para a produção de peças plásticas. A optimização da qualidade e do design das peças e, simultaneamente, a redução do custo de um modo sistemático é possível recorrendo à simulação do processo de injecção durante a fase de projecto. Mais ainda, os processos de tentativa e erro no final da fase de produção podem afectar negativamente tanto o custo do molde como os prazos de entrega. A utilização de ferramentas precisas de simulação do processo de moldação por injecção permite ao fabricante de moldes acrescentar valor para os seus clientes e é um passo importante para a oferta de soluções integradas de desenho da peça e do molde. O presente trabalho apresenta o desenvolvimento de um código paralelo para a simulação do enchimento do processo de moldação por injecção. O algoritmo resolve a equação de Navier-Stokes em três dimensões em malhas não-estruturadas e recorrendo a um método sequencial. A posição da frente do fundido é captado pelo método VOF e a temperatura é calculada utilizando uma equação de transporte. Foram utilizados dois métodos para discretizar as equações de derivadas parciais: elementos finitos e volumes finitos. Estes métodos de discretização foram testados para uma variedade de casos e os resultados foram comparados com soluções analíticas e experimentais quando possível. O método de resolução foi testado recorrendo a 80 processadores em paralelo e os resultados mostram boa eficiência sem perda de precisão. O modelo proposto apresenta boa estabilidade, precisão e eficiência na simulação do fluxo não-isotérmico de fluidos viscosos em domínios tri-dimensionais complexos.
Fundação para a Ciência e Tecnologia (FCT) - Ref. SFRH/BD/19632/2004
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Shen, Chih-Lung, and 沈志隆. "SINGLE-PHASE THREE-WIRE INVERTER FOR PV POWER INJECTION AND POWER QUALITY CONTROL." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/65538699947797813823.
Full textAbstract:
博士國立中正大學
電機工程研究所
91
The objective of this dissertation is to develop a single-phase three-wire inverter system for PV power injection and power quality control. The proposed system can process PV power, improve power factor, eliminate current harmonics, fully or partially deal with re-active power and distortion power, balance real power at source sides, take into account highly distorted line voltages, and accommodate three-phase three-wire systems. To perform PV power injection, inverter current commands for drawing maximum power and in phase with mains voltages are derived. Based on the commands, the processed power between the two output ports of a single-phase three-wire inverter system is equal, which yields zero neutral current. To function as an active power filter, current commands are derived and an approach to determine the consumed power for a single-phase three-wire is discussed. In addition, a current controller for wave shaping is designed, which can be applied to un-/and balanced three-phase three-wire systems. For highly distorted line voltages, a minimum-apparent-power-point-tracking (MAPPT) algorithm is proposed to further improve power factor. For utilizing the maximum installation capacity of the inverter system and improving power quality, the proposed system can condition its output reactive power and distortion power dynamically. A limit sphere is defined to confine inverter power. Thus, this single-phase three-wire PV inverter system can not only draw maximum real power from PV arrays but can filter current harmonics and improve power factor. For further illustration, the proposed inverter system is designed to inject PV power into utility lines, balance real power at source sides and perform active power filtering even when the main voltages are highly deformed. To achieve the desired features, current commands are derived with nonlinear programming (NLP) method to obtain optimal inverter currents and a fast-zero-phase-detection (FZPD) algorithm is proposed to quickly find the phase of the fun-damental component of a distorted voltage. With the FZPD algorithm, the inverter system can yield better power quality over that with conventional zero-crossing detection (ZCD) method. Simulated and experimental results have verified that the single-phase three-wire PV inverter system can fulfill all the pre-mentioned features.
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Hsu, Chih-Chung, and 徐志忠. "Three-Dimensional Flow Analysis for the Simulation of Fluid-assisted Injection Molding Process." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/92g2vx.
Full textAbstract:
博士國立清華大學
化學工程學系所
105
Fluid-assisted injection molding (FAIM) process has brought a breakthrough development for the traditional injection molding industry. The fluid cores out a network of hollow channels throughout the mold cavity to reduce the cost of energy and plastic evidently. In the recent years, the improvements both in the numerical methods and computer hardware have promoted the application of CAE in the modeling of the injection molding process. The major drawbacks of the Hele-Shaw approximation, commonly used today as a means of simplifying the simulation of FAIM process, are the inherent loss of the ability to predict the important physical three-dimensional phenomena for fluid penetration such as blow-out behavior, corner effect, secondary penetration and the finger effect. This study presents an implicit finite volume approach to simulate the three-dimensional mold filling problems encountered during the injection molding. The described numerical model deals with the three-dimensional non-isothermal flow of incompressible, non-Newtonian fluids with moving interfaces. The collocated finite volume method and the SIMPLER (Semi-Implicit Method for Pressure Linked Equations Revised) segregated algorithm are used to discretize and solve the flow governing equations. All vector or tensor variables are computed in their Cartesian components, and hence no coordinate transformation is required, which considerably simplifies the complicated fully three-dimensional primitive variables flow calculation. In addition, a high resolution interface capturing scheme M-CICSAM (Modified-Compressive Interface Capturing Scheme for Arbitrary Meshes) is adopted to solve the advection equation to capture the sharp interface on a Eulerian framework. In order to verify the accuracy of this preliminary study, the study first review the predictability of this developed method in the general common free surface and fluid penetration calculation example. Further this study investigates the analysis on relatively simple geometry of three-dimensional mold to study the general 3D phenomena in FAIM process, such as primary and secondary fluid penetration, and fingering effect in order to verify the correctness of the current approach. Moreover, diverse full shot FAIM processes such as overflow and pushback molding process verify mutually with the experimental results on industrial applications. The results show that our novel three-dimensional numerical model is able to predict the complex fluid penetration behaviors in the real mold and the predictions are also consistent with the experimental results to further verify the accuracy of our approach.
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Yang, Wen-Hsien, and 楊文賢. "Three-Dimensional Finite Volume Method for the Simulaiton of Mold Filling in Injection Molding." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/25192241356459292417.
Full textAbstract:
博士國立清華大學
化學工程學系
89
Injection molding process has been extensively applied to the production of plastic parts. In the recent years, the improvements both in the numerical methods and computer hardware have promoted the application of CAE in the modeling of the injection molding process. The major drawbacks of the Hele-Shaw approximation, commonly used today as a means of simplifying the simulation of injection molding process, are the inherent loss of the ability to predict the important physical three-dimensional phenomena, and the ambiguity involved in the definition of a mid-plane. This work presents an implicit finite volume approach to simulate the three-dimensional mold filling problems encountered during the injection molding. The described numerical model deals with the three-dimensional non-isothermal flow of incompressible, non-Newtonian fluids with moving interfaces. The collocated finite volume method and the SIMPLE segregated algorithm are used to discretize and solve the flow governing equations. All vector or tensor variables are computed in their Cartesian components, and hence no coordinate transformation is required, which considerably simplifies the complicated fully three-dimensional primitive variables flow calculation. In addition, a bounded compressive high-resolution differencing scheme is adopted to solve the advection equation to capture the interface on a Eulerian framework. This approach effectively solves the flow field in terms of CPU time and memory storage as well as the complicated three-dimensional melt front topology. Extensive calculations were performed for several two- and three-dimensional examples to assess the accuracy, efficiency and robustness of the proposed numerical model. To validate the proposed methodology, several typical examples of free-surface testing problems were analyzed. Moreover, the accuracy of the present three-dimensional model is further confirmed through the comparison with the Hele-Shaw model in the simulation of mold filling of several thin mold cavities. Examples of the filling simulations of traditional injection molding, gas-assisted injection molding and IC plastic encapsulation were presented to illustrate the capabilities of the current numerical method. The analysis results of traditional injection molding indicate that the present approach can accurately predict the critical three-dimensional flow phenomena i.e., fountain effect, side wall effect and lateral flows in thickness-change regions. Moreover, for the simulation of real industrial cases of complex geometries, the prediction results are in good agreement with experimental data. In the simulation of gas-assisted injection molding, the three-dimensional model can predict both the polymer and gas injection phases. Moreover, the critical gas penetration behaviors such as penetration length, blow-through, corner effect, fingering effect and gravity effect can also be simulated. Finally, a fully three-dimensional analysis without model simplifications was performed to simulate the plastic encapsulation of a TSOP II of highly-complicated leadframe layout. In this case, the chemorheology of EMC is also included to consider simultaneously the effects of degree-of-cure, temperature and shear-rate on the viscosity of EMC during encapsulation. The analysis results presented in this work indicates that the proposed methodology is a powerful fully three-dimensional analysis tool not only for injection molding but also for the other engineering applications with free-surface flow.
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Ren-HaoLiu and 劉人豪. "Application of In-mold Decoration of Injection Molding in Three-Dimensional Molded Interconnect Devices." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/23403394113877342313.
Full textAbstract:
博士國立成功大學
航空太空工程學系
103
Three Dimensional Molded Interconnect Devices, also known as 3D-MID, integrate both mechanical and electrical functions on plastic substrates. The products are characterized with mechanical structures and electric circuits. This research is based on In-Mold Decoration, also known as IMD, process for 3D-MID. IMD process prints electric circuits on plastic films which are subsequently thermoformed to 3D surface for final products. The thermoformed 3D plastic film is then trimmed and inserted into mold cavity for injection molding to make the final 3D-MID product with electric circuits and mechanical structures. In the first phase of printing ink on plastic films, it ran into an issue of high cost by using conductive silver ink paste for printing. In this research, a new process had been developed to increase the conductivity and lowered the cost by using conductive ink with electroplating process. Experiment results showed that after adding 20% of conductive carbon black, the resistance was 104 for printed lines of 0.9mm in width 40mm in length on PC films. The resistance dropped to 1.3 if treated with electroplating. The issue of phase 2 was the deformation of the plastic films during thermoforming because of the high temperature of punch and die. The film was then deformed by tensile stress and the printed circuits were distorted. A semispherical thermoforming die with a diameter of 100 mm had been developed for the study. PC films with 0.178 mm thick were used to investigate the transformation of 2D electric circuits to 3D surface and the mapping from 3D to 2D. The experiment results showed that the deformation is sever along the sides. The deformation ratio from the experiment was 47.6% versus 49.4% from the simulation of deformation model. The errors of the deformation model were 10.3 ＆ 5.8% in X- ＆ Y- directions; respectively, while the errors of T-SIM, a commercially available deformation model, were 17.2 ＆ 20.0% in X- ＆ Y- directions, respectively. The challenge was burrs on the cutting edge of the plastic films in phase 3 for trimming. A trimming die was developed to study the phenomenon with PC films of 1 mm thick. The results showed that there were four distinctive areas in the cross section of film cutting edge (1) Roll-over; (2) Shear zone or burnish; (3) Rupture zone or fracture; (4) Burr. There were always burrs of 63±17.4 m long on PC-film edges after trimming. The burr’s length increased with film temperature or the clearance between die and film. When the clearance became small, the zones of burnish and fracture had bigger portion. If it got large, the zones of burnish and fracture became narrow. In phase 4, there were warpage of the plastic films during heating and cooling because of the difference of surface temperatures. The product was then hard to assemble. A round-plate die and 80% PC ＆ 20% ABS had been used to study the effect. PC films of 0.178 mm was inserted in mold cavity for injection molding. Control of the mold temperature was the major factor that affected the warpage. The experiment results showed that material temperature of 250℃ would cause short shots and the worst warpage of 3.2 mm. Warpage was improved to 0.63 mm if mold temperature dropped to 90℃.
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Lin, Lung-Shing, and 林龍星. "Design and Implementation of Single-Switch Three-Phase Wind Power Converter with Harmonic Injection Mechanism." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/72w399.
Full textAbstract:
碩士國立成功大學
電機工程學系
102
This thesis presents design and implementation of the single-switch three-phase wind power converter with harmonic injection mechanism. In order to obtain optimal output power of the wind turbine generator (WTG) at different wind speeds, a maximum-power-point-tracking (MPPT) mechanism is required. Furthermore, to improve the input power-factor of the wind energy conversion system (WECS), the conventional single-switch three-phase boost rectifier is employed. However, the input current of the conventional single-switch boost rectifier exhibits a relatively large fifth-order harmonic, which leads to low input PF. Therefore, in order to improve the conversion efficiency for WECS, a MPPT mechanism is employed and proposed in the single-switch three-phase boost rectifier. Moreover, the input fifth-order harmonic current of the single-switch boost rectifier can be reduced by adopting the harmonic injection mechanism. Finally, a 1kW prototype circuit of the single-switch three-phase wind power converter is built to verify the performances using MPPT and harmonic injection mechanisms.
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HSU, DENG-FENG, and 許登豐. "Design and Implementation of Three-Phase Vienna Rectifier Using Zero-Sequence Voltage Injection on SPWM." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/34720002880759502184.
Full textAbstract:
碩士南臺科技大學
電機工程系
105
Power electronic converter technology is widely used in electrical appliances, in which the diode rectifier circuit on the power system to bring serious current total harmonics distortion (THD) and reactive power that resulting in lower power utilization. Research on high power factor (PF) and low input current harmonics is an important project for the Rectifier technology, the input current of an active three-phase power-factor-correction (PFC) rectifier is required to have a total harmonic distortion less than 5% and a power factor greater than 0.99. Active three-phase Vienna Rectifier is two-phasor midpoint-clamped three-level rectifier architecture. The Three-phase Vienna Rectifier is with high power factor, low input current harmonics, less switching elements, and lower power switch and diode voltage stress. This Vienna Rectifier do not consider the upper and lower leg short circuit, thus the delay time of the drive signal for the upper and lower arm does not need to consider. In the conditional three-phase six-switch PFC Rectifier using state space pulse width modulation (SVPWM) technology has eight state-space. When a three-phase Vienna Rectifier operated, the potential at the switch side depends on the switching state of the switch relative to the direction of the corresponding current path, the SVPWM technology has 27 state-spaces, and the calculation of the switch state control is quite complicated. This thesis proposes a zero-sequence voltage injection in SPWM basic voltage modulated quantity in the current control loop of the Vienna Rectifier. Thus, the three-phase Vienna Rectifier switching state have the similar 27 states of SVPWM technology. The zero-sequence voltage injection method can simplify to write the program or easily to design by the hardware circuit, simultaneously the Vienna Rectifier voltage range is higher than SPWM, the input voltage can be raised to 260V and to enhance the utilization of the power system. Finally, a prototype of three-phase Vienna Rectifier with an input voltage of 200-260V, output voltage of 400V, and output power of 3000W is built to verify the correctness and feasibility of zero-sequence voltage injection method.
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Enouy, Robert. "Continuum Approach to Two- and Three-Phase Flow during Gas-Supersaturated Water Injection in Porous Media." Thesis, 2010. http://hdl.handle.net/10012/5659.
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Degassing and in situ formation of a mobile gas phase takes place when an aqueous phase equilibrated with a gas at a pressure higher than the subsurface pressure is injected in water-saturated porous media. This process, which has been termed supersaturated water injection (SWI), is a novel and hitherto unexplored means of introducing a gas phase into the subsurface. Herein is a first macroscopic account of the SWI process on the basis of continuum scale simulations and column experiments with CO2 as the dissolved gas. A published empirical mass transfer correlation (Nambi and Powers, Water Resour Res, 2003) is found to adequately describe the non-equilibrium transfer of CO2 between the aqueous and gas phases. Remarkably, the dynamics of gas-water two-phase flow, observed in a series of SWI experiments in homogeneous columns packed with silica sand or glass beads, are accurately predicted by traditional two-phase flow theory which allows the corresponding gas phase relative permeability to be determined. A key consequence of the finding, that the displacement of the aqueous phase by gas is compact at the macroscopic scale, is consistent with pore scale simulations of repeated mobilization, fragmentation and coalescence of large gas clusters (i.e., large ganglion dynamics) driven entirely by mass transfer. The significance of this finding for the efficient delivery of a gas phase below the water table in relation to the alternative process of in-situ air sparging and the potential advantages of SWI are discussed.
SWI has been shown to mobilize a previously immobile oil phase in the subsurface of 3-phase systems (oil, water and gas). A macroscopic account of the SWI process is given on the basis of continuum-scale simulations and column experiments using CO2 as the dissolved gas and kerosene as the trapped oil phase. Experimental observations show that the presence of oil ganglia in the subsurface alters gas phase mobility from 2-phase predictions. A corresponding 3-phase gas relative permeability function is determined, whereas a published 3-phase relative permeability correlation (Stone, Journal of Cana Petro Tech, 1973) is found to be inadequate for describing oil phase flow during SWI. A function to predict oil phase relative permeability is developed for use during SWI at high aqueous phase saturations with a disconnected oil phase and quasi-disconnected gas phase. Remarkably, the dynamics of gas-water-oil 3-phase flow, observed in a series of SWI experiments in homogeneous columns packed with silica sand or glass beads, are accurately predicted by traditional continuum-scale flow theory. The developed relative permeability function is compared to Stone’s Method and shown to approximate it in all regions while accurately describing oil flow during SWI. A published validation of Stone’s Method (Fayers and Matthews, Soc of Petro Eng Journal, 1984) is cited to validate this approximation of Stone’s Method.
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Lin, Yu-Wan, and 林鈺婉. "Study of Gas Penetration Characteristics in Gas-Assisted Injection Molding by Three-Dimensional Computer-Aided Engineering." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/ea3977.
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碩士中原大學
機械工程研究所
91
Gas-assisted injection molding is an innovative molding process. Although GAIM can greatly improve product quality, it is difficult to control gas penetration in a desired way. Therefore, mold designers must try and error repeatedly in order to obtain optimal processing conditions. Commercial CAE software can offer solutions to design products better and economically. But gas penetration characteristics are not appeared in 2.5D simulation, so 3D real elements are necessary to be used in simulation of gas-assisted injection molding. In this research, we study gas penetration by 3D simulation and use Cluster Computing system to reduce calculation time. The application of a finite volume discretization and volume-of-fluid method has been demonstrated to simulate three-dimensional gas-assisted injection molding processes. An effective fluid concept is to compute segregated multi-fluid flows. The modified Cross model and Arrhenius temperature equation are implemented in the numerical scheme in order to describe the rheological properties of polymer flows. Before simulating a plate, gas injection parameter should be set in a right way. So we chose to set gas velocity. In addition, without considering gas compressibility, the simulated result on a spiral part showed that temperature of gas front was so high that polymer becomes melted. And gas penetration slanted seriously. This phenomenon was over and should be corrected. In this study, 3D simulation results for the plate model were similar to real observation in experiment. The forecast length of gas first penetration was 113mm, almost the same as the experiment.
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Chen, Ying-Chang, and 陳穎昌. "Development of Three-dimensional In-mold Decoration Technology Combining Roll-to-roll, Thermoforming and Injection Molding." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/10569601242219619893.
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碩士國立高雄應用科技大學
模具工程系
99
IMD(In-Mold Decoration) makes melt in filling process to form with pattern structure of plastic and simplify the process. It`s satisfied to require mass production by injection molding technology.IMD technology are classified to three part that is IMR (In-Mold Roller),IML (In-Mold Label ) and IMF (In-Mold Forming). IML are used to rules or simple flat pieces of plastic surfaces. IML are used to mass production but small changes in curvature sample. Lastly IMF are used to sample that is few, exquisite, varied and big Curvature.First IMF`s steps used micro-structure or pattern printed copying to the film, then through hot pressed form film of structure. Lastly using forming film put into injection cavity to IMD process by injection molding. This technology can breakthrough traditional design of the injection and improve the appearance of sample , increased durability, etc. IMF process products affected by shape, mold design, the impact of parameters come up the case of rupturing, stress concentration or wrinkled that resulting in poor appearance of the product. In this study, UV-cure embossing process, thermoforming and injection molding design, process planning and product testing. Traditions IMD only apply to plane or on the surface relaxation if the curvature is bigger that it is easy to cause wrinkled or structural break. IMF`s molding is considerable different with tradition molding, for such a process must be to design a series of mold. Mold design and produce of IMF can`t effectively control the material deformation because the absence of IMF process flow analysis of plastic materials. Having to test mold many times and mold repair, to get the desired quality. The purpose of the study are IMF mold design and the use of UV-curable roll forming micro-structure, thermoforming and injection molding experimental analysis in the IMF process to discuss the effects of process parameters, the parameter optimization. Finally, the use of mold sensor discuss the effects of mold temperature, flow and pressure difference and scanning electron microscopy observation watching appearance, to find the best mold design and process design criteria.
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Tung, Feng-Hsuan, and 董豐瑄. "Reactive Power and Capacitor Voltage Controls for Three-phase Vienna Converters Using Zero-sequence Voltage Injection." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/84z36q.
Full textAbstract:
碩士國立中山大學
電機工程學系研究所
106
This thesis presents a reactive power and capacitor voltage controls method for the Vienna converters in three-phase three-wire system. The control method can realize rectification and low current total harmonic distortion (THD), which can make converter operate with power factor correction (PFC)mode, PF leading mode, PF lagging mode and achieve two loads output power balance or unbalance. This control method can enhance converter ability and make it more flexible to application. Furthermore, the reactive power and capacitor voltage balance controls operation limit had been analyzed. In addition, the converter operation principle had been derived and either reactive power or unbalance load controls method were analyzed. Besides, the relation and limitations between both control is investigated. This method used the carrier-based pulse width modulation and zero-sequence injection method to achieve the requirements. Finally, a three-phase Vienna converters was built with DSP TMS320F28335. All the key concepts and ideas developed in this thesis is implemented in this hardware system and verified by the experimental results.
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Kim, Sang-Woo. "Three-dimensional simulations for the filling stage of the polymer injection molding process using the finite element method." 2005. http://catalog.hathitrust.org/api/volumes/oclc/70832718.html.
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Yuan, Chengwu. "A new relative permeability model for compositional simulation of two and three phase flow." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2517.
Full textAbstract:
Chemical treatments using solvents and surfactants can be used to increase the productivity of gas-condensate wells with condensate banks. CMG’s compositional simulator GEM was used to simulate such treatments to gain a better understanding of design questions such as how much treatment solution to inject and to predict the benefits of such treatments. GEM was used to simulate treatments in vertical wells with and without hydraulic fractures and also horizontal wells. However, like other commercial compositional simulators, the flash calculations used to predict the phase behavior is limited to two phases whereas a three-phase flash is needed to accurately model the complex phase behavior that occurs during and after the injection of treatment solutions. UTCOMP is a compositional simulator with three-phase flash routine and attempts were made to use it to simulate such well treatments. However, this is a very difficult problem to simulate and all previous attempts failed because of numerical problems caused by inconsistent phase labeling (so called phase flipping) and the discontinuities this causes in the relative permeability values.
In this research, a new relative permeability model based on molar Gibbs free energy was developed, implemented in a compositional simulator and applied to several difficult three-phase flash problems. A new way of modeling the residual saturations was needed to ensure a continuous variation of the residual saturations from the three-phase region to the two-phase region or back and was included in the new model. The new relative permeability model was implemented in the compositional reservoir simulator UTCOMP. This new relative permeability model makes it is unnecessary to identify and track the phases. This method automatically avoids the previous phase flipping problems and thus is physically accurate as well as computationally faster due to the improved numerical performance. The new code was tested by running several difficult simulation problems including a CO2 flood with three-hydrocarbon phases and a water phase.
A new framework for doing flash calculations was also developed and implemented in UTCOMP to account for the multiple roots of the cubic equation-of-state to ensure a global minimum in the Gibbs free energy by doing an exhaustive search for the minimum value for one, two and three phases. The purpose was to determine if the standard method using a Gibbs stability test followed by a flash calculation was in fact resulting in the true minimum in the Gibbs free energy. Test problems were run and the results of the standard algorithm and the exhaustive search algorithm compared.
The updated UTCOMP simulator was used to understand the flow back of solvents injected in gas condensate wells as part of chemical treatments. The flow back of the solvents, a short-term process, affects how well the treatment works and has been an important design and performance question for years that could not be simulated correctly until now due to the limitations of both commercial simulators and UTCOMP. Different solvents and chase gases were simulated to gain insight into how to improve the design of the chemical treatments under different conditions.text
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Marotta, Phillip. "Assessing the impact of criminal justice system involvement on injection drug and sexual HIV risks in three key-affected populations." Thesis, 2019. https://doi.org/10.7916/d8-k0bt-a096.
Full textAbstract:
Despite increased involvement in the criminal justice system among populations of migrants, people who inject drugs, and drug-involved men in community corrections, few studies investigate associations between involvement in the criminal justice system and sexual and injection drug risks among these key-affected populations and their intimate partners. To address these gaps the following dissertation study investigated the association between exposures to the criminal justice system and sexual and injection drug risks among three key affected populations: 1) male labor migrants in Almaty, Kazakhstan, 2) people who inject drugs and their intimate partners in Almaty, Kazakhstan, and 3) drug-involved men in community corrections in New York City, NY in the United States. Using the three-paper model, the following dissertation sheds new insights into how exposures to the risk environment shape sexual and injection HIV risks to inform HIV prevention research and practice with populations disproportionately involved in criminal justice systems.
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Whiteside, Benjamin R., Ken B. Howell, Michael T. Martyn, and Robert Spares. "Micromoulding: extreme process monitoring and in-line product assessment." 2009. http://hdl.handle.net/10454/2782.
Full textAbstract:
NoAdvances in micromoulding technology are now allowing mass production of complex, three-dimensional functional products having sub-milligram masses and carefully tailored surface finishes. In order to create a viable manufacturing process for these components, accurate process monitoring and product evaluation are essential in order to highlight process problems and production of substandard parts. The present study describes work implementing a suite of sensors on a commercial micromoulding machine for detailed process interrogation. Evaluation of demoulded products is performed with a single camera based system combined with custom software to allow for three-dimensional characterisation of products during the process.