Dissertations / Theses on the topic 'Multipass operation'
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Zhong, Yu Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "A study of the cutting performance in multipass abrasive waterjet machining of alumina ceramics with controlled nozzle oscillation." Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2008. http://handle.unsw.edu.au/1959.4/41216.
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An experimental investigation has been undertaken to study the depth of cut in multipass abrasive waterjet (AWJ) cutting of an 87% alumina ceramic with controlled nozzle oscillation. The experimental data have been statistically analysed to study the trends of the depth of cut with respect to the process parameters. It has been found that multipass cutting with controlled nozzle oscillation can significantly increase the depth of cut. Within the same cutting time and using the same cutting parameters other than the jet traverse speed, it has been found that multipass cutting with nozzle oscillation can increase the depth of cut by an average of 74.6% as compared to single pass cutting without nozzle oscillation. Furthermore, a multipass cutting with higher nozzle traverse speeds can achieve a larger depth of cut than a single pass cutting at a low traverse speed within the same cutting time. A recommendation has been made for the selection of appropriate process parameters for multipass cutting with nozzle oscillation. In order to estimate the depth of cut on a mathematical basis, predictive models for the depth of cut in multipass cutting with and without nozzle oscillation have been developed using a dimensional analysis technique. The model development starts with the models for single pass cutting which are then extended to multipass cutting where considerations are given to the change of the actual standoff distance after each pass and the variation of kerf width. These predictive models has been numerically studied for their plausibility by assessing their predicted trends with respect to the various process variables, and verified qualitatively and quantitatively based on the experimental data. The model assessment reveals that the developed models correlate very well with the experimental results and can give adequate predictions of this cutting performance measure in process planning.
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Guéguen, Arnaud, and David Auvray. "Multipath Mitigation on an Operational Telemetry Link." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595646.
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ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaTransmitter mobility and multipath propagation make the telemetry channel both time and frequency selective, which results in telemetry link errors, sometimes in crucial flight phases. Only part of these impairments are compensated by various diversity techniques, but a fast converging adaptive channel equalization is probably the best suited and most cost effective solution. This paper first presents an analysis of mobile multipath propagation in telemetry based on recorded operational signals, both at the transmitter and at the receiver sides. Then it provides performance evaluation of a novel blind equalizer, assessed by offline processing of the recorded signals. The paper focuses on typical environments at a flight test centre, which exhibit critical multipath channel characteristics, namely during parking, taxiway and flight. The channel analysis exploits the recorded signals as well as the time frequency response of the novel equalizer filter. Performance evaluation shows that the equalizer outperforms state of the art Constant Modulus Algorithm (CMA). In particular, it is shown to significantly increase the telemetry link availability even in severe conditions, sometimes from nearly 0% to almost 100%, whereas the CMA fails to improve the signal quality as soon as the channel varies in time.
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Jiang, Mo. "Pharmaceutical crystallization design using micromixers, multiphase flow, and controlled dynamic operations." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98708.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015.Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 198-214).
Crystallization is a key unit operation in the pharmaceutical industry. Control of crystallization processes can be challenging when undesirable phenomena such as particle attrition and breakage occur. This thesis describes the controlled crystallization of pharmaceuticals and amino acids for more efficient manufacturing processes and better efficacy of products. Crystallization equipment is designed so that (1) the undesirable phenomena do not occur at all, and/or (2) the phenomena that do occur are carefully controlled. One key strategy is to exploit dual-impinging jets and multiphase flow to decouple nucleation and growth so that they can be individually controlled. Various configurations of micromixers were designed to provide controlled nucleation. Based on the dual-impinging-jet (DIJ) configuration, a physical explanation was provided for the discovery that a cooling micromixer can generate small crystals of uniform size and shape. An alternative design replaces the micromixing with the application of ultrasonication to decouple nucleation and flow rates. Based on these nucleation methods, a novel continuous crystallizer is designed where the slurry flow is combined with an air flow to induce a multiphase hydrodynamic instability that spontaneously generates slugs where the crystals continue to grow. These slugs are well-mixed without having the mixing blades in traditional crystallizer designs that induce undesirable uncontrolled crystallization phenomena. Another key strategy is to increase the degrees of freedom in the dynamic operation of the crystallizers. In the slug-flow continuous crystallizer, extra degrees of freedom for control of the crystal growth are created by spatially varying the temperature profile along the tube. In a semi-continuous crystallizer configuration, continuous seeding using a DIJ mixer is combined with growth rate control in a stirred tank to experimentally demonstrate the manufacture of uniform-sized crystals. In addition, temperature-cycling experiments are designed in batch crystallizers to substantially change crystal shape with only a small number of cycles. Experimental validation confirms that the proposed crystallizer designs reduce production time and equipment cost by orders of magnitude while suppressing secondary nucleation, attrition, and aggregation/agglomeration-dominant but undesired phenomena that worsen the ability to control the properties of crystals produced by most existing crystallizer designs.
by Mo Jiang.
Ph. D.
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Bougas, Vassilis. "The development of a crystal modulator using a multipath reflection technique." Thesis, London Metropolitan University, 1993. http://repository.londonmet.ac.uk/3301/.
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An AOP lumped crystal transverse modulator has been developed, based upon a novel crystal cut, which operates at much lower driving voltages than presently available commercial state of the art modulators. With the latter, the modulation bandwidth is limited by the requirement for driving voltages in the range of 115V to 250V, which are difficult and expensive to produce using existing semiconductor technology. The reduction in driving voltage leads to an increased modulation bandwidth; low voltage wideband drivers are readily available. The modulator's novelty lies in a composite crystal scheme which allows a light beam to be reflected back and forth many times. The voltage requirement is reduced by a factor dependent on the number of times the light beam passes through the crystals. This modulator does not require a half wave plate and can therefore operate at any optical wavelength as is also the case with some of the existing designs. But in addition, unlike the existing designs, this novel modulator allows for multicolour multibeam operation. Using four AOP crystals (15.0mm length, 16.5mm width and 2.5mm thickness) a half wave voltage of 65V has been achieved after seven passes. The extinction ratios obtained were in the range of 50:1 to 100:1. A theory developed and supported by experimental results shows that the extinction ratio depends upon the angle of propagation of the light bean through the crystals. Improvements in this area are suggested. Finally, a technique for extending the operational bandwidth of any modulator is presented. The bandwidth of the multipath modulator was 70MHz.
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Aliaga, Rivera Cristhian Neil. "An unsteady multiphase approach to in-flight icing /." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112552.
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Ice accretion is a purely unsteady phenomenon that is presently approximated by most icing codes using quasi-steady modeling. The accuracy of ice prediction is thus directly related to the arbitrarily prescribed time span during which the impact of ice growth on both flow and droplets is neglected. The objective of this work is to remove this limitation by implementing a cost-effective unsteady approach. This is done by fully coupling, in time, a diphasic flow (interacting air and droplet particles) with the ice accretion model. The two-phase flow is solved using the Navier-Stokes and Eulerian droplet equations with dual-time stepping in order to improve computational time. The ice shape is either obtained from the conservation of mass and energy within a thin film layer for glaze and mixed icing conditions, or from a mass balance between water droplets impingement and mass flux of ice for rime icing conditions. The iced surface being constantly displaced in time, Arbitrary Lagrangian-Eulerian terms are added to the governing equations to account for mesh movement. Moreover, surface smoothing techniques are developed to prevent degradation of the iced-surface geometric discretization. For rime ice, the numerical results clearly show that the new full unsteady modeling improves the accuracy of ice prediction, compared to the quasi-steady approach, while in addition ensuring time span independence. The applicability of the unsteady icing model for predicting glaze ice accretion is also demonstrated by coupling the diphasic model to the Shallow Water Icing Model. A more rigorous analysis reveals that this model requires the implementation of local surface roughness and that previous quasi-steady validations cannot be carried out using a small number of shots, therefore the need for unsteady simulation.
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Tazi, Hemida Mohamed. "Regularite l**(p) maximale pour une classe d'operateurs a caracteristiques multiples." Rennes 1, 1988. http://www.theses.fr/1988REN10046.
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Il s'agit de regarder dans le 1er sujet la regularite l**(p) maximale pour une classe d'operateurs a characteristiques multiples. Dans le 2eme sujet, nous etudions l'hypoellipticite maximale d'un systeme d'operateurs pseudo-differentiels
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Skirpan, Zachary. "Multiphase CFD benchmark of experimental critical heat flux data at PWR operating conditions." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127300.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 85-89).
Critical Heat Flux (CHF) in flow boiling represents the fundamental upper limit for thermal hydraulic performance of PWR fuel. Currently, the nuclear industry relies on expensive, prototypical experiments using electrically heated, full-height rod assemblies to determine the limit of the boiling crisis. The development of next-generation Multiphase Computational Fluid Dynamics (M-CFD) approaches for the prediction of CHF seeks to represent the detailed physics of the boiling process up to its critical condition, rather than estimating it from ad-hoc thresholds. In this work we evaluate the advancement in M-CFD boiling attained by the Consortium for Advanced Simulation of Light water reactors (CASL). The CASL approach builds off an industry-lab-university collaboration with individual validation of interfacial momentum closures and wall boiling models.
The M-CFD simulations were implemented in the commercially available STAR-CCM+ software, and benchmarked against experimental observations of CHF collected at the University of Wisconsin by Duarte. In this work, 15 M-CFD simulations were completed. Boiling curves were generated for each test case. The modelled boiling characteristics were then compared to expected physical parameters to determine model accuracy. Structural spacers are the main driver of vapor accumulations leading to the breakdown of boiling heat transfer at CHF. Interestingly, M-CFD solutions indicate that the Departure from Nucleate Boiling (DNB) first occurs in areas not measured by the experimental thermal couples used to detect CHF, possibly resulting in a late experimental detection. Additionally, sensitivity studies are conducted for relevant model terms to understand their impact on CHF.
Leveraging the results from this sensitivity study, it is suggested that improved predictions could 1) increase the turbulent dispersion at the wall to account for turbulence under-prediction and 2) increase the minimum bubble size limiter to reflect physically observed coalesced bubble sizes after departure. For future work, higher spatial resolution measurements for detecting DNB are suggested for better experimental CHF predictions. A fully mechanistic approach for modeling the heat flux partitioning and subsequent wall boiling in M-CFD is also needed to more effectively simulate the proper heat transfer mechanisms and boiling physics before CHF. It is the hope that through this work and further M-CFD heat transfer investigations that similar methods may be validated for CHF detection and streamline the fuel design process in the nuclear industry.
by Zachary Skirpan.
S.M.
S.M. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering
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Zhu, Zhen. "CHARACTERIZATION OF GLOBAL POSITIONING SYSTEM EARTH SURFACE MULTIPATH AND CROSS CORRELATION FOR AIRCRAFT PRECISION APPROACH OPERATIONS USING SOFTWARE RADIO TECHNOLOGY." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1156276678.
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Bello, Oladele O. [Verfasser]. "Modelling particle transport in gas oil sand multiphase flows and its applications to production operations / submitted by Oladele O. Bello." [Clausthal-Zellerfeld] : [Univ.-Bibliothek], 2008. http://d-nb.info/990729931/34.
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Alwan, Abdulmalik Abdullah [Verfasser], and Wilhelm [Akademischer Betreuer] Dominik. "Numerical Reservoir Simulations of Multiphase Pump Operations on the Rütenbrock Sour Gas Field, Northwest-Germany / Abdulmalik Abdullah Alwan. Betreuer: Wilhelm Dominik." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2011. http://d-nb.info/1014827817/34.
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Velmurugan, Naveen. "Distributed dynamics of influx during MPD operations : modelling and estimation." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLM018.
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Lors du forage d’un puits de pétrole, il est courant de subir un influx non désiré de fluides provenant du réservoir. Ce manuscrit porte sur l’étude de la dynamique de l’écoulement en résultant dans le réservoir et le puis, pendant les opérations de forage à pression contrôlée (MPD en anglais). La modélisation repose sur des équations de conservation, qui débouchent sur un modèle d’écoulement biphasique appelé modèle à dérive de flux. Celui-ci prend la forme d’un système hyperbolique d’équations de transport, alors que l’évolution de la pression dans le réservoir suit une dynamique gouvernée par une équation parabolique de diffusion. Nous proposons des schémas numériques permettant d’approcher les solutions de ces deux systèmes dynamiques. Nous synthétisons ensuite des observateurs permettant d’estimer le débit entrant depuis le réservoir. Ces observateurs du système couplé puits-réservoir prennent des formes différentes selon que le caractère distribué de chacune des dynamiques (puits ou réservoir) est négligé ou non. Nos estimateurs reposent sur la mesure de la pression en tête de puits, où un capteur est systématiquement installé dans les opérations de forage à pression contrôlée. L’existence d’un capteur de pression installé au fond du puits, plus rare, modifie la synthèse d’observateurs, d’une manière que nous détaillons. Pour chaque observateur, nous montrons la convergence des estimations de pression et de débit distribués vers leurs valeurs théoriquesWhile drilling an oil well, unwanted influx of fluids from the reservoir may occur. This manuscript studies the dynamics of the resulting fluid flow in the wellbore and the reservoir, during managed pressure drilling (MPD) operations. We study the phenomena using first-principle approach that leads to a modified two phase flow model called the drift-flux model (DFM). The model takes the form of a hyperbolic system of transport equations, whereas the reservoir pressure dynamics is given by a parabolic diffusion equation. We propose appropriate numerical schemes for both. Then, we propose different observer designs to estimate the influx from the reservoir into the wellbore. The observers for the coupled wellbore-reservoir system take different forms, as we combine the distributed and the reduced order models for each system. We propose to use the choke pressure as a measurement that is typically available on a MPD operational site, i.e. topside sensing. However, availability of the bottom hole pressure modifies the observer design, in ways we detail. We show convergence of the observers to the true values of reservoir pore pressure and influx, in each case
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Lang, Philipp [Verfasser], and Peter [Akademischer Betreuer] Woias. "Fabrication methods and unit operations for multiphase direct fluorination in mini- and microreactors = Herstellungsmethoden und Einheitsverfahren für Mehrphasen-Direktfluorierung in Mini- und Mikroreaktoren." Freiburg : Universität, 2012. http://d-nb.info/1123469512/34.
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Bermúdez, guzmán Mario. "Novel control techniques in multiphase drives : direct control methods (DTC and MPC) under limit situations." Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0061/document.
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Les entraînements électriques polyphasés ont acquis une importance particulière ces derniers temps pour leur utilisation dans des applications où la fiabilité présente un intérêt pour des raisons économiques et de sécurité. Cette thèse se centre sur le développement de techniques de commande en mode instantané pour contrôler de manière optimale les machines polyphasées, en analysant leur tolérance dans différentes conditions de fonctionnement, telles que lors de l’atteinte de limites électriques (limites de tension, de courant et de niveau maximum de magnétisation) ou de défauts de type phase ouverte. Tout d’abord, la technique DTC est proposée pour gérer le cas de défaut de type phase ouverte dans la machine polyphasée. Une comparaison de la tolérance à la défaillance des commandes de type DTC par rapport à d’autres techniques de commande est réalisée, permettant une conclusion sur les forces et les faiblesses des méthodes analysées. Enfin, un contrôleur de courant optimal est développé utilisant des techniques MPC permettant une utilisation optimale de la capacité de couple du système en cas de limitations électriques. Des résultats de simulation et des validations expérimentales sont effectués pour corroborer les approches initiales, en utilisant des cas particuliers d’entraînements pentaphasés commandés avec différents sous-espaces de commande dans le domaine fréquentielMultiphase drives have gained special relevance in recent times for their use in applications where reliability is of interest for economical and safety reasons. This Thesis focuses on the development of direct control techniques to optimally control multiphase machines, analyzing their tolerance to different limit operating conditions, such as electrical constraints (voltage, current and magnetization level limits) or failure situations such as an open-phase fault. First, the DTC technique is proposed to manage the open-phase fault operation of the multiphase machine. A comparison of the fault-tolerant capability of DTC with other control techniques is carried out, to conclude the strengths and weaknesses of the analyzed methods facing this limit operation. Finally, an optimal current controller is developed using MPC techniques that allows the optimal utilization of the system’s torque capability under electrical limitations. Simulation results and experimental validations are obtained to corroborate the initial approaches, through the use of particular cases of five-phase drives controlled using different frequency-domain control subspaces
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Coine, Clément. "Continuous linear and bilinear Schur multipliers and applications to perturbation theory." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD074/document.
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Dans le premier chapitre, nous commençons par définir certains produits tensoriels et identifions leur dual. Nous donnons ensuite quelques propriétés des classes de Schatten. La fin du chapitre est dédiée à l’étude des espaces de Bochner à valeurs dans l'espace des opérateurs factorisables par un espace de Hilbert. Le deuxième chapitre est consacré aux multiplicateurs de Schur linéaires. Nous caractérisons les multiplicateurs bornés sur B(Lp, Lq) lorsque p est inférieur à q puis appliquons ce résultat pour obtenir de nouvelles relations d'inclusion entre espaces de multiplicateurs. Dans le troisième chapitre, nous caractérisons, au moyen de multiplicateurs de Schur linéaires, les multiplicateurs de Schur bilinéaires continus à valeurs dans l'espace des opérateurs à trace. Dans le quatrième chapitre, nous donnons divers résultats concernant les opérateurs intégraux multiples. En particulier, nous caractérisons les opérateurs intégraux triples à valeurs dans l'espace des opérateurs à trace puis nous donnons une condition nécessaire et suffisante pour qu'un opérateur intégral triple définisse une application complètement bornée sur le produit de Haagerup de l'espace des opérateurs compacts. Enfin, le cinquième chapitre est dédié à la résolution des problèmes de Peller. Nous commençons par étudier le lien entre opérateurs intégraux multiples et théorie de la perturbation pour le calcul fonctionnel des opérateurs autoadjoints pour finir par la construction de contre-exemples à ces problèmesIn the first chapter, we define some tensor products and we identify their dual space. Then, we give some properties of Schatten classes. The end of the chapter is dedicated to the study of Bochner spaces valued in the space of operators that can be factorized by a Hilbert space.The second chapter is dedicated to linear Schur multipliers. We characterize bounded multipliers on B(Lp, Lq) when p is less than q and then apply this result to obtain new inclusion relationships among spaces of multipliers.In the third chapter, we characterize, by means of linear Schur multipliers, continuous bilinear Schur multipliers valued in the space of trace class operators. In the fourth chapter, we give several results concerning multiple operator integrals. In particular, we characterize triple operator integrals mapping valued in trace class operators and then we give a necessary and sufficient condition for a triple operator integral to define a completely bounded map on the Haagerup tensor product of compact operators. Finally, the fifth chapter is dedicated to the resolution of Peller's problems. We first study the connection between multiple operator integrals and perturbation theory for functional calculus of selfadjoint operators and we finish with the construction of counter-examples for those problems
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Galanis, Marlo, and Trim Gjana. "Grönt är skönt för planeten, men är det lönt för värderingen? : En studie om sambanden mellan företagens hållbarhetsarbete och deras värdering på den svenska aktiemarknaden." Thesis, Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-177726.
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Bakgrund: För att relativvärderingar inte skall bli missvisande sätts krav på att de jämförda bolagen faktiskt är tillräckligt lika för att tillåta en jämförelse. I praktiken väljs generellt bolag inom samma bransch, medan teorin förespråkar för att skillnader i finansiella variabler som bland annat tillväxt och risk måste kontrolleras för. Tidigare forskning har oftast endast studerat hur de finansiella variablerna påverkar multipelvärdet. Relativvärdering påverkas dock även av pågående marknadstrender, förutsatt att dessa trender influerar börsvärdet. Andra variabler än branschtillhörighet och finansiella sådana kan således påverka värdet och därmed även behöva kontrolleras för, innan en relativvärdering utförs. Hållbarhetsarbete är en sådan trend som vuxit sig väldigt stark på senare tid. Hållbarhetsarbete i allmänhet och ESG-betyg i synnerhet är områden som ännu inte är helt kartlagda, speciellt vad gäller deras påverkan på ett företags värdering. Syfte: Studiens syfte är att analysera om det föreligger några samband mellan ESG-betyg och multipelvärden samt hur dessa samband i så fall ser ut och varför, för svenska stora och medelstora bolag listade på Nasdaq Stockholm Large och Mid Cap. Metod: Studien har utförts med en kvantitativ strategi, där samband mellan ESG-betyg och multipelvärden undersökts för årsskiftet 2020/2021, genom multipla regressionsanalyser. Totalt 151 svenska bolag med erhållna ESG-betyg har analyserats genom att deras multipelvärden för fyra olika multiplar använts som beroende variabler, samt där ESG-betyg och ett antal finansiella kontrollvariabler utgjort oberoende variabler i regressionerna. Underlaget till studien har utgjorts av data från databasen Refinitiv samt årsredovisningar. Slutsats: Resultatet visar att ett statistiskt signifikant negativt samband föreligger mellan ESG-betyg och multipelvärden. Att lägre betyg går hand i hand med högre värdering och vice versa, är fallet genomgående för såväl Mid Cap som Large Cap.Background: In order for relative valuation not to be misleading, it is required that the companies compared are in fact sufficiently equal to allow a comparison. In practice, these companies are generally chosen within the same industry, while theory advocates that differences in financial variables such as growth and risk are more important and must be controlled for. Previous research has mostly only studied how these financial variables affect the value of multiples. However, relative valuation is also affected by ongoing market trends, provided that these trends influence market value. Variables other than financial ones and industry affiliation may thus affect the value and have to be controlled for, before a relative valuation using multiples is performed. Sustainability is one such trend that has grown tremendously strong in recent times. Sustainability work in general and ESG scores in particular are areas that have not yet been fully mapped, especially in terms of their impact on a company’s valuation. Purpose: The purpose of this study is to analyze potential relationships between ESG scores and values of multiples, how these relationships look and why, for large and medium-large Swedish companies listed on the Nasdaq Stockholm Large and Mid Cap lists. Methodology: A quantitative approach was used for the study, where the relationship between ESG scores and values of multiples was examined for the turn of the year 2020/2021, through multiple regression analyzes. A total of 151 Swedish companies, with published ESG scores, were analyzed using their multiples’ values for four different multiples as dependent variables in the regressions. ESG scores and a number of financial control variables constituted the independent variables in said regressions. The basis for the study has consisted of data from the Refinitiv database and annual reports. Conclusions: The results show that there is a statistically significant negative relationship between ESG scores and the values of multiples. The fact that lower ESG scores go hand in hand with higher valuations and vice versa, is the case throughout for both Mid Cap as well as Large Cap.
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Vacher, Blandine. "Techniques d'optimisation appliquées au pilotage de la solution GTP X-PTS pour la préparation de commandes intégrant un ASRS." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2566.
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Les travaux présentés dans ce document portent sur des problèmes d'optimisation dans le domaine de la logistique interne des entrepôts. Le domaine est soumis à une forte concurrence et est en plein essor, poussé par les besoins croissants du marché et favorisé par l'automatisation. L'entreprise SAVOYE construit des équipements et propose sa propre solution GTP (Goods-To-Person) pour la préparation de commandes. La solution utilise un système de stockage automatisé appelé X-Picking Tray System (X-PTS) et achemine les charges automatiquement à des postes de travail via des carrousels pour effectuer des opérations séquencées. C'est un système de systèmes particulièrement complexe qui offre de nombreuses applications aux techniques de la recherche opérationnelle. Tout cela définit le périmètre applicatif et théorique des travaux menés dans cette thèse. Nous avons d'abord traité un problème d'ordonnancement de type Job Shop avec des contraintes de précédences. Le contexte particulier du problème a permis de le résoudre en un temps polynomial avec un algorithme exact. Celui-ci a permis de calculer les dates d'injection des charges provenant des différents flux de sortie du stockage pour s'agréger sur un carrousel, dans un ordre donné. Ainsi, la gestion inter-allées du stockage PTS a été améliorée et le débit du flux de charges maximisé, depuis le stockage jusqu'à un poste. Nous avons ensuite étudié des algorithmes de tri tels que le tri par base et développé un algorithme de tri en ligne, utilisé pour piloter des systèmes autonomes de tri appelés Buffers Séquenceurs (BS). Placés en amont de chaque poste de travail dans la solution GTP, les BS permettent de délocaliser la fonction de tri en aval du stockage, augmentant de facto le débit des flux de sortie. Enfin, nous avons considéré un problème de séquencement consistant à trouver une extension linéaire d'un ordre partiel minimisant une distance avec un ordre donné. Nous proposons de le résoudre par une approche de programmation linéaire en nombres entiers, par la construction de programmes dynamiques et par des heuristiques de type glouton. Une heuristique efficace a été développée en se basant sur des appels itératifs d'un des programmes dynamiques, permettant d'atteindre une solution proche ou égale à l'optimum en un temps très court. L'application de ce problème aux flux de sortie non ordonnés du stockage X-PTS permet de réaliser un pré-tri au niveau des carrousels. Les diverses solutions développées ont été validées par simulation et certaines ont été brevetées et/ou déjà été mises en application dans des entrepôtsThe work presented in this PhD thesis deals with optimization problems in the context of internal warehouse logistics. The field is subject to strong competition and extensive growth, driven by the growing needs of the market and favored by automation. SAVOYE builds warehouse storage handling equipment and offers its own GTP (Goods-To-Person) solution for order picking. The solution uses an Automated Storage and Retrieval System (ASRS) called X-Picking Tray System (X-PTS) and automatically routes loads to workstations via carousels to perform sequenced operations. It is a highly complex system of systems with many applications for operational research techniques. All this defines the applicative and theoretical scope of the work carried out in this thesis. In this thesis, we have first dealt with a specific scheduling Job Shop problem with precedence constraints. The particular context of this problem allowed us to solve it in polynomial time with exact algorithms. These algorithms made it possible to calculate the injection schedule of the loads coming from the different storage output streams to aggregate on a carousel in a given order. Thus, the inter-aisle management of the X-PTS storage was improved and the throughput of the load flow was maximized, from the storage to a station. In the sequel of this work, the radix sort LSD (Least Significant Digit) algorithm was studied and a dedicated online sorting algorithm was developed. The second one is used to drive autonomous sorting systems called Buffers Sequencers (BS), which are placed upstream of each workstation in the GTP solution. Finally, a sequencing problem was considered, consisting of finding a linear extension of a partial order minimizing a distance with a given order. An integer linear programming approach, different variants of dynamic programming and greedy algorithms were proposed to solve it. An efficient heuristic was developed based on iterative calls of dynamic programming routines, allowing to reach a solution close or equal to the optimum in a very short time. The application of this problem to the unordered output streams of X-PTS storage allows pre-sorting at the carousel level. The various solutions developed have been validated by simulation and some have been patented and/or already implemented in warehouses
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Gao, Zhufeng. "Assembly and test operations with multipass requirement in semiconductor manufacturing." Thesis, 2014. http://hdl.handle.net/2152/24901.
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In semiconductor manufacturing, wafers are grouped into lots and sent to a separate facility for assembly and test (AT) before being shipped to the customer. Up to a dozen operations are required during AT. The facility in which these operations are performed is a reentrant flow shop consisting of several dozen to several hundred machines and up to a thousand specialized tools. Each lot follows a specific route through the facility, perhaps returning to the same machine multiple times. Each step in the route is referred to as a "pass." Lots in work in process (WIP) that have more than a single step remaining in their route are referred to as multi-pass lots. The multi-pass scheduling problem is to determine machine setups, lot assignments and lot sequences to achieve optimal output, as measured by four objectives related to key device shortages, throughput, machine utilization, and makespan, prioritized in this order. The two primary goals of this research are to develop a new formulation for the multipass problem and to design a variety of solution algorithms that can be used for both planning and real-time control. To begin, the basic AT model considering only single-pass scheduling and the previously developed greedy randomized adaptive search procedure (GRASP) along with its extensions are introduced. Then two alternative schemes are proposed to solve the multipass scheduling problem. In the final phase of this research, an efficient procedure is presented for prioritizing machine changeovers in an AT facility on a periodic basis that provides real-time support. In daily planning, target machine-tooling combinations are derived based on work in process, due dates, and backlogs. As machines finish their current lots, they need to be reconfigured to match their targets. The proposed algorithm is designed to run in real time.text
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Laporte, Pierre-André. "A wave pipeline-based WCDMA multipath searcher for a high speed operation." Thesis, 2007. http://spectrum.library.concordia.ca/975598/1/MR40887.pdf.
Full textAbstract:
The multiplexing technique of the Wideband-Code Division Multiple Access (WCDMA) is widely applied in the third generation (3G) of cellular systems. The WCDMA uses scrambling codes to differentiate the mobile terminals. In a channel, multipaths may occur when the transmitted signal is reflected from objects in the receiver's environment, so that multiple copies of the signal arrive at the antenna at different moments. Thus, a wideband signal may suffer frequency selective fading due to the multipath propagations. A Rake receiver is often used to combine the energies received on different paths, and a multipath searcher is needed to identify the multipath components and their associated delays. Correlating some shifted versions of the scrambling code with an incoming signal results in energy peaks at the multipath locations, when the locally generated scrambling sequence is aligned with the scrambling sequence of the incoming signal. A path acquisition in such a process requires a speed of millions of Multiply-Accumulate (MAC) cycles per second. The performances of the multipath searcher are mainly determined by the resolution and the acquisition time, which are often limited by the operation speed of the hardware resources. This thesis presents the design of a multipath searcher with a high resolution and a short acquisition time. The design consists of two aspects. The first aspect is of the searching algorithm. It is based on a double-dwell algorithm and a verification stage is introduced to lower the rate of false alarms. The second aspect in the design is the circuit of the searcher. This circuit is expected to operate at the chip rate of 3.84 MHz and the search period is chosen to be equal to the time interval of 5 slots, which requires a high operation speed of the computation units employed in the circuit. Moreover, in order to reduce the circuit complexity, only one Complex Multiplier-Accumulator (CMAC), instead of several ones in many existing searcher circuits, is employed to perform all the computation tasks without extending the search period, which make the computation time in the circuit more critical. Aiming at this challenge of the high speed requirement, a structure of the CMAC cell is designed with the technique of the wave pipeline, which permits the signal propagation through the circuit stages without constraints of clocks. For a good use of this technique, the circuit blocks are made to have equalized delay, by means of pass transistor logic cells, and by keeping such a delay short, the total computation time of the CMAC can be made within the required time limit of the searching. A complete circuit of the CMAC has been developed. It has two versions, with the Normal Process Complementary Pass Logic (NPCPL) and the Complementary Pass-Logic Transmission-Gates (CPL-TG), respectively. The structures of the arithmetic units have been chosen carefully so that the fan-in/fan-out constraints of the NPCPL and the CPL-TG logics are taken into consideration. The results of the simulation with a 0.18 om models have shown that this wave pipelined CMAC can process four inputs of 8 bits at a rate of 830 Mb/s. In order to evaluate the effectiveness of the searching algorithm, a Matlab simulation of the searcher circuit has been conducted. It has been observed that the proposed multipath searcher can lead to low probabilities of misdetection and false alarm for the test cases recommended by the 3 rd Generation Partnership Project (3GPP) standard. A test chip of the CMAC circuit has been fabricated in a CMOS 0.18 om technology process. The circuit is currently under test.
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hwa, Hanhe Jean, and 黃靜慧. "The Structure Analysis of Multiples of fractional Operations for Elementary Students." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/20161416699935533831.
Full textAbstract:
碩士國立臺中教育大學
數學教育學系在職進修教學碩士學位班
95
The purpose of this research is to establish a set of test questions regarding integral multiples of fractions. Moreover, to develop a structural graph based on the resulting scores analyzed by the IRS method in order to further study the students’ knowledge structure of fractions’ integral multiples. Based on the researcher’s references from the Fractional Integral Multiples Concept is divided into three sub-concepts: Common Fraction Multiplied by Integer, Improper Fraction Multiplied by Integer, and Mixed Fraction Multiplied by Integer. According to the sub-concepts, the researcher developed a set of self-composed test questions of Integral Multiples of Fractions. The subjects of this study are two classes of fifth grader students from a Taichung County elementary school. After taking the test, the IOSP computer program of Test Question Relationship Structure Analysis Method will be utilized to analyze the scoring data in order to obtain the resulting information from the structure graph of fractions multiplied by integers. According to the results of the structure graph, this research reached the following conclusion: Through the researcher’s written examination and graph analysis, the cognition sequence of the tested students’ fractions multiplied by integers. Concept was discovered. With respect to the common fraction being multiplied by the integer: (1) common fraction is multiplied by the integer, its integral number does not carry over, (2) common fraction is multiplied by the integer, its integral number carries over, (3) common fraction definition. With respect to the improper fraction being multiplied by the integer: (1) improper fraction is multiplied by the integer, its integral number carries over, (2) improper fraction is multiplied by the integer, its integral number does not carry over, (3) improper fraction definition. With respect to the mixed fraction being multiplied by the integer: (1) mixed fraction is multiplied by the integer, its integral number does not carry over, (2) mixed fraction definition, (3) mixed fraction is multiplied by the integer, its integral number carries over. This study also discovers that, within the fractions multiplied by integers, the mixed fraction is multiplied by the integer, its integral number carries over are the most difficult. It was also discovered that the students were not clear on the definition of fractions, as well as the relationship between the mixed fractions’ integers and common fractions The above results are combined to propose several suggestions to serve as a source of reference for educators and further studies.
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Hsu, Cheng-Lin, and 徐俊霖. "A Wideband High-Gain CMOS Operational Amplifier with Multipath Structure." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/20765603056683719752.
Full textAbstract:
碩士義守大學
電子工程學系
87
A CMOS operational amplifier utilizing multipath structure is described. By combining the low-frequency amplifier’s high dc gain and the high-frequency amplifier’s wide bandwidth, we are able to design a CMOS operational featured both high dc gain and wide unity-gain bandwidth. Unlike those with cascode output stages which suffer from reduced output voltage range, our op amp design has nearly rail-to-rail output swing. We design multipath op amp based on the UMC 0.5um CMOS technology. With this design, a gain of 80dB and a unity-gain bandwidth of 520MHz has been achieved. The circuit has been fabricated in a single chip, occupies an area of 1800*1800 .
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Kroupa, Ryan Daniel. "Investigation of a Multiphase Twin-screw Pump Operating at High Gas Volume Fractions." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9099.
Full textAbstract:
The use of twin-screw pumps for moving fluids is not new technology but its application to wet gas compression (high gas volume fraction [GVF]) is still considered relatively new. There are many advantages for using twin-screw pumps for oil field applications; three of the immediate improvements include reducing hardware costs, reducing well bore pressure, and producing a pressure boost to move the product to a central collection facility.
While there are many advantages to using twin-screw pumps in wet gas applications, there are some problems that have been encountered while operating at high GVFs. When operating at high GVF, over 95 percent twin-screw pumps experience a severe loss of efficiency and an increase of operating temperature. A common way to increase the efficiency while operating in the high GVF range includes adding a liquid recirculation system where a portion of liquid is stored downstream of the pump and is injected into the pump inlet. These systems lower the effective GVF of the multiphase fluid below 95 percent in order to increase the pump efficiency.
The first objective is to characterize the performance of a twin-screw pump fitted with a liquid recirculation system while operating under high GVF conditions. The second objective is to investigate the transient heat rise associated with high GVF operation.
While traditional twin-screw pumps can be fitted with a liquid recirculation system to allow them to operate under high GVF conditions the pumps themselves are not optimized for wet gas compression and still suffer performance penalties. The results of this investigation show that the liquid recirculation system can allow the pump to operate under high GVF but the heat added to the system reduces the systems efficiency. Without a method of removing the heat generated in the pumping process the pump will not run at its optimal efficiency. The following investigation provides recommendations for further research in area of multiphase pumping using twin-screw pumps based on the characterization and transient studies provided in this thesis.
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YANG, YU O., and 楊玉娥. "Operational Meaning of Time for Multipara during the Early Postpartum at Home." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/95573955911331346588.
Full textAbstract:
碩士國立臺灣大學
護理學研究所
81
The purpose of this study explores the operational meaning of time for multipara during the early postpartum at home. This study is conducted by field method. In the process of research, the researcher,as a care-giver of the multipara following the first postpartum day till discharge. Collected the data by in- depth interviews on the 2nd, 4th, 10th, 14th days after the subjects discharged.Meanwhile, the researcher recorded the verbal expressions of those multipara mothers. By means of content analysis, the verbal behaviors of the subjects were systematically analyzed and categorized. The results show that the operational meaning of time for multipara during the early postpartum at home can be categorized as follows:The referrents include the women themselves, new-born babies, older children, and other family members. The rates are 36.1％ (583/1614),49.7％(802/1614), 9.7％(157/1614),4.8％(72/1614). The assessment encompasses both quantatative and qualitative meanings.The rates are 27％(435/1614), 73％(1179/1614). On the one hand,the quantitative meaning implicates that time is an important resource of life that the multipara evaluate their new life patherns according to the sufficency and efficency of the amount or fast or slow of the disposal velocity through their subjective experiences. Most multipara complain about the pressure of time.Amazingly, the rate is as high as 96.7％. On the other hand,the qualitative meaning indicates that time is a Marker of life events. The women regard time a means to orient, modify,and depict their living patterns after change. The result of this study can be applied as a references for nurses when taking care of multipara during postpartum.
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解文明. "A study on the operation strategies of customized plastic machinery industry manufacturer-a case of the multiplas enginery co.,ltd." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/21812891425728642918.
Full textAbstract:
碩士國立政治大學
經營管理碩士學程(EMBA)
99
As the polymer materials industry's rapid growth, plastic materials are widely used in daily life in many different areas, and provides plastic materials processing products required equipment for plastic machinery industry increasingly important role. The plastic machinery industry's annual output of more than 400 million, and in the export ratio is as high as 80%, is only next to the machine tools - the second largest of the general mechanical engineering industry; However, because of the development of economic globalization, and the Mainland China, and so the impact of the rise of emerging countries, makes plastic machinery industry severely affected and move out. In this turbulent rapid, enterprises will no longer be able to meet with the status quo of ivory, Instead, the enterprises must continuously by innovation development increase energy, set up an enterprise product differentiation, creativity to meet customer demand for customized orders entity value, to enhance the competitive advantage of corporate self; In the case of the company policy of doing, according to the enterprise's external environment of industrial and enterprise itself has a condition, and then examine its strategy of trading on the formation and the resulting policy effects. This last line to policy six dimensions theory as policy analysis of the case, for taking different from planned volume production of the plastic machinery industry firms, and to customized to operating mode of representation firms, by depth interviews of research methods, to conduct research on enterprise policy cases; in the face of increasingly fierce international competition environment, for the future development of the environment, using for cases of operation of the enterprise strategy, will bring together the cases previously operating experience, provide relevant industry operators reference scenario, common around the world to market niche, to really improve the domestic plastic machinery industry in the world of competitive advantage, as well as industrial companies in the sustainable development lay the cornerstone.
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Glier, Michael W. "An Experimental Examination of a Progressing Cavity Pump Operating at Very High Gas Volume Fractions." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9238.
Full textAbstract:
The progressing cavity pump is a type of positive displacement pump that is capable of moving nearly any fluid. This type of pump transports fluids in a series of discrete cavities formed by the helical geometries of its rigid rotor and elastomeric stator. With appropriate materials for the rotor and stator, this pump can move combinations of liquids, suspended solids, and gasses equally well. Because of its versatility, the progressing cavity pump is widely used in the oil industry to transport mixtures of oil, water, and sediment; this investigation was prompted by a desire to extend the use of progressing cavity pumps to wet gas pumping applications.
One of the progressing cavity pump's limitations is that the friction between the rotor and stator can generate enough heat to damage the rotor if the pump is not lubricated and cooled by the process fluid. Conventional wisdom dictates that this type of pump will overheat if it pumps only gas, with no liquid in the process fluid. If a progressing cavity pump is used to boost the output from a wet gas well, it could potentially be damaged if the well's output is too dry for an extended period of time. This project seeks to determine how a progressing cavity pump behaves when operating at gas volume fractions between 0.90 and 0.98.
A progressing cavity pump manufactured by seepex, model no. BN 130-12, is tested at half and full speed using air-water mixtures with gas volume fractions of 0.90, 0.92, 0.94, 0.96, and 0.98. The pump's inlet and outlet conditions are controlled to produce suction pressures of 15, 30, and 45 psi and outlet pressures 0, 30, 60, 90, 120, and 150 psi higher than the inlet pressure. A series of thermocouples, pressure transducers, and turbine flow meters measures the pump's inlet and outlet conditions, the flow rates of water and air entering the pump, and pressures and temperatures at four positions within the pump's stator.
Over all test conditions, the maximum recorded temperature of the pump stator did not exceed the maximum safe rubber temperature specified by the manufacturer. The pump’s flow rate is independent of both the fluid's gas volume fraction and the pressure difference across the pump, but it increases slightly with the pump's suction pressure. The pump's mechanical load, however, is dependent only on the pressure difference across the pump and increases linearly with that parameter. Pressure measurements within the stator demonstrated that the leakage between the pump's cavities increases with the fluids gas volume fraction, indicating that liquid inside the pump improves its sealing capability. However, those same measurements failed to detect any appreciable leakage between the two pressure taps nearest the pump's inlet. This last observation suggests that the pump could be shortened by as much as 25 percent without losing any performance in the range of tested conditions; shortening the pump should increase its efficiency by decreasing its frictional mechanical load.
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Bento, Catia Sofia Cruz. "Adaptação da exploração de albufeiras a cenários climáticos futuros." Master's thesis, 2019. http://hdl.handle.net/10316/86422.
Full textAbstract:
Dissertação de Mestrado Integrado em Engenharia do Ambiente apresentada à Faculdade de Ciências e TecnologiaAo longo dos anos, a variabilidade climática ganhou importância devido aos impactos negativos no planeta Terra. A partir dos fenómenos meteorológicos extremos e da incerteza destes eventos, surgiu a necessidade de analisar o comportamento e disponibilidade dos recursos hídricos para conseguir satisfazer as necessidades hídricas. Na presente dissertação, pretendeu se avaliar diferentes estratégias e reduzir os efeitos dos eventos de escassez de recursos, a partir da simulação e adaptação da exploração do empreendimento de fins múltiplos de Odeleite-Beliche, para diferentes cenários climáticos futuros no período de 2021/2050, com a aplicação de diferentes regras de exploração alternativas. O desempenho do sistema é simulado com base num sistema de apoio à decisão, o software AQUATOOL+. De forma a ir ao encontro do objetivo da dissertação, a metodologia considerada envolveu: a caracterização do empreendimento de fins múltiplos de Odeleite-Beliche; a análise dos cenários climáticos futuros a utilizar; a definição de regras de exploração; a simulação do comportamento da albufeira; e a análise do desempenho do sistema com recurso a indicadores de desempenho. Para além da simulação do sistema com a regra de exploração padrão (SOP, do inglês Standard Operating Policy), foram experimentadas quatro regras de exploração diferentes, nas quais se impuseram restrições crescentes à satisfação da procura para menores volumes armazenados, variando a condição de ativação dessas mesmas restrições. No estudo de caso, a condição de ativação foi definida em função de volumes armazenados, tendo-se experimentado quatro valores diferentes para o início da imposição de restrições à satisfação da procura. Os resultados obtidos mostram que, a simulação com a regra SOP apresenta um menor número de situações de défices, contudo a gravidade desses défices pode ser elevada. Com as outras regras, à medida que as restrições se iniciam com um volume armazenado na albufeira superior, a quantidade de défices gerados é superior, contudo a gravidade dos défices é menor. No geral, os resultados mais positivos foram obtidos com a regra SOP e com a regra de exploração com o nível de ativação mais baixo. Importante realçar que para a população é preferível, em geral, confrontar-se com pequenos défices em largos períodos de tempo do que grandes défices em curtos períodos de tempo. Concluindo, todas as simulações com aplicação de regras de exploração apresentam vantagens e desvantagens, a sua aplicação deve ser devidamente fundamentada e estudada caso a caso.
Over the years, climate variability has become increasingly important due to its negative impacts on the planet Earth. Therefore, from the extreme weather phenomena and the uncertainty of these events, appeared the necessity to analyze the behavior and disponibility of water resources, to allow the satisfaction of the basic water needs. In this dissertation, it is intended to study and evaluate different strategies to prevent and reduce the effect of water scarcity events, through the simulation and adaptation of the multipurpose system of Odeleite-Beliche operation to different future climate scenarios in the period 2021/2050, with the application of different operating rules. The simulation of the system performance is based on a decision support system, software AQUATOOL+. To meet the objectives, the methodology used involved: the characterization of the multipurpose system of Odeleite-Beliche; the analysis of the future climate scenarios; definition of the operating rules; simulation of the water resource system; and system performance evaluation with performance criteria. Beyond the system simulation with the standard operating rule, SOP (Standard Operating Policy), four different rules were evaluated, each one with increasing restrictions imposed on the demand satisfaction for smaller storage volumes, varying the activation condition for the restrictions. In the case of study, the activation condition was defined from the storage volume, having tested four different values for the beginning of the imposition of restrictions on demand satisfaction. The results showed that the simulation with the rule SOP, show a lower number of deficit situations, however the severity of those deficits can be bigger. With the other rules, when the restrictions initiate with a volume storage in the water resource system higher, the amount of deficits is higher, however the severity of the deficits is lower. The most positive results were obtained with the rule SOP, and with the operating rule with the activation level with the smaller storage volume. To the population, in general, it is better to have smaller deficits for a large period of time, than big deficits for a shorter period of time. In conclusion, all the simulations with application of operating rules introduce advantages and disadvantages, however to be applied the system must be studied case by case.