Rozprawy doktorskie na temat „Schéma passif”
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Mrad, Imed. "La méthode du recuit simulé pour la synthèse automatique de schéma électrique équivalent : Application à la modélisation de composant et à l'adaptation à large bande". Châtenay-Malabry, Ecole centrale de Paris, 1997. http://www.theses.fr/1997ECAP0588.
Pełny tekst źródłaLai, Dac Kien. "Contribution à l'Optimisation du Dimensionnement de Composants Passifs Intégrés pour l'Electronique de Puissance". Phd thesis, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00567450.
Pełny tekst źródłaAkhavanfoomani, Aria. "Derivative-free stochastic optimization, online learning and fairness". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAG001.
Pełny tekst źródłaIn this thesis, we first study the problem of zero-order optimization in the active setting for smooth and three different classes of functions: i) the functions that satisfy the Polyak-Łojasiewicz condition, ii) strongly convex functions, and iii) the larger class of highly smooth non-convex functions.Furthermore, we propose a novel algorithm that is based on l1-type randomization, and we study its properties for Lipschitz convex functions in an online optimization setting. Our analysis is due to deriving a new Poincar'e type inequality for the uniform measure on the l1-sphere with explicit constants.Then, we study the zero-order optimization problem in the passive schemes. We propose a new method for estimating the minimizer and the minimum value of a smooth and strongly convex regression function f. We derive upper bounds for this algorithm and prove minimax lower bounds for such a setting.In the end, we study the linear contextual bandit problem under fairness constraints where an agent has to select one candidate from a pool, and each candidate belongs to a sensitive group. We propose a novel notion of fairness which is practical in the aforementioned example. We design a greedy policy that computes an estimate of the relative rank of each candidate using the empirical cumulative distribution function, and we proved its optimal property
Lai, Dac Kien. "Contribution à l’optimisation du dimensionnement de composants passifs intégrés pour l’électronique de puissance". Grenoble INPG, 2010. https://hal.science/tel-00567450.
Pełny tekst źródłaDue to the trend of integration in power electronics, a hybrid device combining three conventional passive components including an inductor, a capacitor and a transformer has been studied at G2Elab since 2001. This component called LCT provides both advantages in size reduction and performance. However, classical design methods do not guarantee optimal results. Therefore this thesis proposes a new optimization approach. The optimization firstly base on an electromagnetic modeling developped from the Lumped Element Equivalent Circuit (LEEC) method that had already studied at G2Elab, then on an analytical thermal modeling. The design optimization tool can minimize the volume of LCT components in subjecting to principal thermal constraint. Experimental works is essential manner to validate these developed models
Jobic, Yann. "Numerical approach by kinetic methods of transport phenomena in heterogeneous media". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4723/document.
Pełny tekst źródłaA novel kinetic scheme satisfying an entropy condition is developed, tested and implemented for the simulation of practical problems. The construction of this new entropic scheme is presented. A classical hyperbolic system is approximated by a discrete velocity vector kinetic scheme (with the simplified BGK collisional operator), but applied to an inviscid compressible gas dynamics system with a small Mach number parameter, according to the approach of Carfora and Natalini (2008). The numerical viscosity is controlled, and tends to the physical viscosity of the Navier-Stokes system. The proposed numerical scheme is analyzed and formulated as an explicit finite volume flux vector splitting (FVS) scheme that is very easy to implement. It is close in spirit to Lattice Boltzmann schemes, but it has the advantage to satisfy a discrete entropy inequality under a CFL condition and a subcharacteristic stability condition involving a cell Reynolds number. The new scheme is proved to be second-order accurate in space. We show the efficiency of the method in terms of accuracy and robustness on a variety of classical benchmark tests. Some physical problems have been studied in order to show the usefulness of both schemes. The LB code was successfully used to determine the longitudinal dispersion of metallic foams, with the use of a novel indicator. The entropic code was used to determine the permeability tensor of various porous media, from the Fontainebleau sandstone (low porosity) to a redwood tree sample (high porosity). These results are pretty accurate. Finally, the entropic framework is applied to the advection-diffusion equation as a passive scalar
Soares, Carlos Walter Alves. "Metáforas e significados na composição musical : quando o compositor revisita e ressignifica seus passos". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/148285.
Pełny tekst źródłaThis thesis presents technical elucidations and post-compositional interpretations of four pieces composed during my doctorate degree: "Io" and "Calisto", for solo piano, "Ganimedes" and "Europa" for two pianos. The music composition is approached in three steps: a) description of the musical and extra musical aspects of the first stages of the composition; b) investigation of the sonorous characteristics of the pieces; c) construction of fictional postcompositional interpretations, imagining Jupiter's moons as compositional and interpretative impetus. The third stage is achieved under the perspective of the contemporary theory of metaphor proposed by George Lakoff and Mark Johnson, and posteriorly developed by Mark Turner and Gilles Falconnier. Through the introduction of metaphor categories, the cross-domain mapping, the image schema, the invariance principle, the mental spaces and the conceptual blending, some connections are established between the metaphoric concepts and the metaphoric conceptualization of music. This contributes to the approximation between the main characteristics of the pieces and the scenes/actions proposed in the first step of the post-compositional interpretations. This work proposes a reflection about the attribution of meanings on the musical composition in a global perspective, where extra musical elements can expand the assimilation of the musical phenomenon, as well as to contribute to the pedagogy of musical composition and the production of collaborative works.
Smiley, W. J. "Collision detection scheme for unmanned aircraft using passive Panospheric§T§M Imaging sensor". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ44858.pdf.
Pełny tekst źródłaKubrak, Boris. "Direct numerical simulation of gas transfer at the air-water interface in a buoyant-convective flow environment". Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/10196.
Pełny tekst źródłaBoutiton, Sophie. "Généralisation des schémas GQ2 et Rabin-Williams : équivalence avec la factorisation des grands nombres". Limoges, 2006. http://aurore.unilim.fr/theses/nxfile/default/2f7cec9e-e03a-447e-bb17-8d20828d1a30/blobholder:0/2006LIMO0007.pdf.
Pełny tekst źródłaThis thesis is about the generalization of the GQ2 and Rabin-Williams schemes. Their security relies on the problem of factorization of large numbers. First we have a look at the security of the GQ2 protocol by giving an estimation of the power of cheating related to the power of factorizing the public key number. Then we prove the overwhelming probability to generate GQ2 keys from general RSA moduli, from moduli composed by more than two factors, or from larger public exponents. Up until now, none of Rabin-Williams type digital signatures have a unique signature exponent when considering any two-factor modulus. We present here a solution that also generalizes the previous schemes. The last chapter is based on an article by Gennaro, Micciancio and Rabin (CCS99). Their results are not improved here but a new proof is given, using technical tools, to prove the validity of some two-factor moduli
Faleh, Alaeddine. "Allocation stratégique d’actifs et ALM pour les régimes de retraites". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10084.
Pełny tekst źródłaThis thesis focuses on the strategic asset allocation models and on their application for the financial reserve management of a pay-as-you-go (PAYG) retirement schemes, especially those with partial provision. The study of the reserve utility for a PAYG system and of their management still leaves a lot to be explored. Classical hypothesis are usually considered too restrictive for the description of the complex reserve evolution. New models and new results have been developed over three levels : economic scenario generation (ESG), numerical optimization techniques and the choice of optimal strategic asset allocation in the case of an Asset-Liability Management (ALM). For the generation of financial and economic scenarios, some ESG performance indicators have been studied. Also, we detailed and proposed to improve ESG construction, notably the choice of the correlation matrix between modelled variables. Then, a set of tools were presented so that we could estimate ESG parameters variety. This thesis has also paid particular attention to numerical techniques of optimum research, which is an important step for the asset allocation implementation. We developed a reflexion about a global optimisation algorithm of a non convex and a noisy function. The algorithm allows for simple modulating, through two parameters, the reiteration of evaluations at an observed point or the exploration of the noisy function at a new unobserved point. Then, we presented new ALM techniques based on stochastic programming. An application to the strategic asset allocation of a retirement scheme with partial provision is developed. A specific methodology for the scenario tree generation was proposed at this level. Finally, a comparative study between proposed ALM model and Fixed-Mix strategy based model was achieved. We also made a variety of a sensitivity tests to detect the impact of the input values changes on the output results, provided by our ALM model
Mojsejenko, Dimitri. "ESTIMATING PASSIVE MATERIAL PROPERTIES AND FIBER ORIENTATION IN A MYOCARDIAL INFARCTION THROUGH AN OPTIMIZATION SCHEME USING MRI AND FE SIMULATION". UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/41.
Pełny tekst źródłaMohamed, Jessica Rose. "The development of a kernel to detect Ziphius cavirostris vocalizations and a performance assessment of an automated passive acoustic detection scheme". Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FMohamed.pdf.
Pełny tekst źródłaThesis Advisor(s): Chiu, Ching-Sang ; Miller, Christopher W. "September 2008." Description based on title screen as viewed on .November 4, 2008. Includes bibliographical references (p. 35-36). Also available in print.
Marchand, Nicolas. "Suivi de la température de surface dans les zones de pergélisol arctique par l'utilisation de données de télédétection inversées dans le schéma de surface du modèle climatique canadien (CLASS)". Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10591.
Pełny tekst źródłaAbstract : High latitude areas currently are the most sensitive to global warming effects. In the next 100 years, temperature could rise up to 3 to 8 ◦C at the North Pole. Permafrost (ground with negative temperatures two years in a row) represents 25% of northern hemisphere lands, and contains huge quantities of "frozen" carbon estimated at 1400 Gt (40 % of the global terrestrial carbon). Recent studies showed that a part (50 %) of the permafrost first few meters could melt by 2050, and 90 % by 2100. The goal of our study is to improve our understanding of ground temperature evolution in arctic areas, especially in snow covered regions. The objective is to discribe the ground temperature all year long with and without a snow cover, and to analyze the evolution of the permafrost’s active layer in relation with the climate variability. We use remote sensing data (fuzzed of MODIS "LST" surface temperatures and AMSR-E "Tb" brightness temperatures) assimilated in the canadian landscape surface scheme (CLASS) coupled to a simple radiative transfer model (HUT). This approach takes into account the advantages of each kind of data in order to achieve two objectives : 1 - build a solid methodology allowing to retrieve ground temperatures, with and without a snow cover, in tundra areas ; 2 - from those retrieved ground temperatures, derive the summer melting duration which can be linked to the permafrost active layer thickness. We describe the models coupling as well as the methodology allowing the adjustement of CLASS input meteorological parameters (essentially the air temperatures and precipitations from the NARR meteorological data base) in order to minimize the simulated LST and Tb in comparison to remote sensing data. By using meteorological station’s ground temperature measurments as a reference for validation in North America tundra areas, results show that the proposed method improves the simulation of ground temperatures when using LST MODIS and Tb at 10 and 19 GHz data to constrain the model, in comparison with model outputs without satellite data. Using the Tb polarization ratio H/V at 10 GHz allows an improvement of the constrain on winter period simulations. An analyze of the error is conducted for summer (1,7 - 3,6 K) and winter (1,8 - 3,5 K). We present climatic applications for future work that meets the second objective of the Ph.D. A better understanding of evolution processes of permafrost, and particularly of the impact of the snow cover, should allow us a better understanding of global warming effects on the permafrost’s melting and the future of their carbon stocks.
Élise, Simon. "Développement d’indices écoacoustiques pour caractériser et suivre l’état et le fonctionnement des écosystèmes coralliens". Thesis, La Réunion, 2019. http://www.theses.fr/2019LARE0041.
Pełny tekst źródłaCoral reefs are the most complex of marine ecosystems, but also the most threatened by ecological disruption resulting directly or indirectly from human activities. Their conservation represents a huge challenge. While maintaining coral reefs as close as possible to their current configurations and dynamics is among the highest priorities, we must also prepare for rapid changes in their functioning and adapt monitoring tools and networks to this new situation. Recent technological advances enabled the emergence of innovative tools with the potential to drastically increase the spatio-temporal resolution of coral reef monitoring. Among these, Passive Acoustic Monitoring (PAM) is on the rise. The aim of this thesis was to improve and facilitate the use of PAM as a tool for the assessment and monitoring of coral reefs’ ecological states and functioning. Soundscape recordings and ecological surveys (reef fish assemblages and habitat) were performed at 31 outer reef slope sites around three Indo-Pacific islands with variable environmental characteristics, including contrasted anthropogenic pressures. Analysing the results obtained with multiple combinations of sampling settings (frequency bandwidth, time of sampling (day/night), and sample duration) allowed the selection of a sampling scheme based on the two types of indices mostly used in coral reef studies. This scheme enables a rapid and reliable categorisation of reef’s ecological states. Based on these sampling guidelines, the capacity of six ecoacoustic indices to evaluate coral reef key functions was demonstrated. By comparing the contributions of PAM and coarse environmental data that could be sampled remotely, the added value of using ecoacoustic indices to predict reef fish assemblage structure was identified and quantified. An application of ecoacoustics to the continuous monitoring of a remote site highlighted the strong potential of PAM as a supporting tool for managers in such context. In view of the amplitude and velocity of expected climatic changes, current observer-based monitoring methods are likely to be exceeded. Combined to other monitoring tools, PAM could contribute to promptly detect ecosystem disturbances, which is essential to understand their causes and put in place rapid and adapted responses
N'guessan, Marc-Arthur. "Space adaptive methods with error control based on adaptive multiresolution for the simulation of low-Mach reactive flows". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC017.
Pełny tekst źródłaWe address the development of new numerical methods for the efficient resolution of stiff Partial Differential Equations modelling multi-scale time/space physical phenomena. We are more specifically interested in low Mach reacting flow processes, that cover various real-world applications such as flame dynamics at low gas velocity, buoyant jet flows or plasma/flow interactions. It is well-known that the numerical simulation of these problems is a highly difficult task, due to the large spectrum of spatial and time scales caused by the presence of nonlinear The adaptive spatial discretization is coupled to a new 3rd-order additive Runge-Kutta method for the incompressible Navier-Stokes equations, combining a 3rd-order, A-stable, stiffly accurate, 4-stage ESDIRK method for the algebraic linear part of these equations, and a 4th-order explicit Runge-Kutta scheme for the nonlinear convective part. This numerical strategy is implemented from scratch in the in-house numerical code mrpy. This software is written in Python, and relies on the PETSc library, written in C, for linear algebra operations. We assess the capabilities of this mechanisms taking place into dynamic fronts. In this general context, this work introduces dedicated numerical tools for the resolution of the incompressible Navier-Stokes equations, an important first step when designing an hydrodynamic solver for low Mach flows. We build a space adaptive numerical scheme to solve incompressible flows in a finite-volume context, that relies on multiresolution analysis with error control. To this end, we introduce a new collocated finite-volume method on adaptive rectangular grids, with an original treatment of the spurious pressure and velocity modes that does not alter the precision of the discretization technique. new hydrodynamic solver in terms of speed and efficiency, in the context of scalar transport on adaptive grids. Hence, this study presents a new high-order hydrodynamics solver for incompressible flows, with grid adaptation by multiresolution, that can be extended to the more general low-Mach flow configuration
Dourado, Diego Marques. "Estratégias para aumento da eficiência espectral e energética em redes TWDM-PON". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-11092017-113611/.
Pełny tekst źródłaThe problem studied is related to the planning of optical access networks TWDM (Time and Wavelength Division Multiplexing), aiming to provide means to meet the increasing bandwidth consumption and, at the same time, associating it to the lowest possible power consumption and providing quality services to the network users. In this context, following the presentation of a literature review, some studies were selected as a reference basis for the study. In this, some wavelength management techniques were analyzed aiming a possible technological migration of the network access equipment at the user side, the optical network units (ONU), whereas it is possible to use efficiently the ONUs distribution in each pair of wavelength. As a result, it becomes possible to switch off some management interfaces thus assuring a degree of power consumption save. In parallel, methods for providing an \"adaptive record\" of ONUs have been aggregated to improve the performance of those ONUs that are migrating and/or entering the network, avoiding collisions between their signals and increasing the chance of their registration in the optical line terminal (OLT). Furthermore, this work deals with the fulfillment of the service agreement (SLA) signed by telecommunications operators and proposes ways to design a passive optical network (PON) in order to offer services with quality metrics assurance (QoS). Different scenarios were treated to vary the percentage of active users on the network, and it was noticed that when the PON operates with low rate of activity (average 10% of active ONUs), it was possible to save over 80% energy in the management interfaces. Moreover, by involving more realistic scenarios in optical networks (50%, in average, of active ONUs), the TWDM-PON saved almost 50% of energy at the interfaces to be configured with low migration period (5 minutes). Additionally, it reached an SLA of approximately 100%, a value considered above the usual when it comes to compliance services. As an emerging technology, TWDM-PON stands out in a scenario that should be designed to be compatible with deployed technologies, and beyond that, to overcome the legacy of PON networks in energy saving and quality of services offered.
Hýl, Petr. "Slovinské národní divadlo v Lublani". Master's thesis, Vysoké učení technické v Brně. Fakulta architektury, 2009. http://www.nusl.cz/ntk/nusl-215582.
Pełny tekst źródłaChen, Shih-Yu, i 陳世又. "Low Power Driving Scheme for Passive Matrix-OLED". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/70083969293937549953.
Pełny tekst źródła國立臺灣大學
電子工程學研究所
91
Abstract Small size passive matrix organic light emitting display (PM-OLED) has the advantages of simple manufacture process and low total cost. Base on the PMOLED characteristics, a low power consumption column driver and row driver was developed for color PMOLED. We provide two methods for reducing the power consumption of driving system: low total current 16-gray scale pulse width modulation (PWM) output driving current control circuit, and a energy recovery design for precharge circuit.
Chen, Wei-Han, i 陳韋翰. "A Hybrid Checkpointing Scheme in Message Passing Systems". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/95930666895997913830.
Pełny tekst źródła國立成功大學
會計學系碩博士班
95
If we apply checkpoint-based protocols to achieve fault-tolerance, besides taking checkpoints, it is a significant issue to ensure that consistent global states can be recovered when failures occur. Additional failure-free coordination overheads are ineluctable so that reduce the performance. Recently, many intensive researches have been studied to eliminate such overheads including by analyzing distributed programs and statically inserting checkpoint statements at the proper places in the source code. In this thesis, we propose a hybrid checkpoint scheme to leverage the advantages of both static analysis and online checkpointing. An algorithm to find orphan-free coupling nodes in extended control flow graph is shown and we apply it to several commonly used inter-process interacting paradigms. Tightly coupling strategy is to avoid any trouble path that checkpoint X happened before checkpoint Y from different processes in the CFG. However,if the application being analyzed may have trouble paths while executing operations in loops, it is unnecessary for tightly coupling strategy to move the checkpoint statement outside the loop to avoid trouble paths. Under our hybrid checkpoint scheme, the extent of recovery from failures can be bounded to at most one checkpoint interval such that domino effect will never appear.
"A multicast overlay scheme for wavelength division multiplexed passive optical networks". 2009. http://library.cuhk.edu.hk/record=b5893893.
Pełny tekst źródłaThesis submitted in: December 2008.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.
Includes bibliographical references (leaves 56-60).
Abstracts in English and Chinese.
Chapter Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Telecommunications network hierarchy --- p.2
Chapter 1.2 --- PON architectures for access networks --- p.4
Chapter 1.2.1 --- TDM-PON --- p.5
Chapter 1.2.2 --- WDM-PON --- p.7
Chapter 1.3 --- Data delivery mode in WDM-PON --- p.8
Chapter 1.3.1 --- Point-to-point --- p.8
Chapter 1.3.2 --- Broadcast --- p.9
Chapter 1.3.3 --- Multicast --- p.10
Chapter 1.4 --- Motivation of this thesis --- p.10
Chapter 1.5 --- Outline of this thesis --- p.13
Chapter Chapter 2 --- Previous Multicast Architectures in WDM-PON --- p.14
Chapter 2.1 --- Introduction --- p.15
Chapter 2.2 --- Previous WDM-PON architectures with multicast capability --- p.15
Chapter 2.2.1 --- Subcarrier multiplexing --- p.16
Chapter 2.2.2 --- All-optical based multicast enabled architecture --- p.18
Chapter 2.3 --- Summary --- p.21
Chapter Chapter 3 --- A Multicast enabled WDM-PON Architecture Using ASK-DPSK Orthogonal Modulation --- p.23
Chapter 3.1 --- Introduction --- p.24
Chapter 3.2 --- System architecture --- p.25
Chapter 3.3 --- Experimental Demonstration --- p.27
Chapter 3.4 --- Discussion --- p.31
Chapter 3.5 --- Summary --- p.36
Chapter Chapter 4 --- A WG filtering and its suppression in quaternary ASK-DPSK based multicast enabled WDM-PON --- p.37
Chapter 4.1 --- Introduction --- p.38
Chapter 4.2 --- Principle of narrowband filtering --- p.38
Chapter 4.3 --- Simulation model --- p.40
Chapter 4.4 --- Simulation results and discussion --- p.42
Chapter 4.4.1 --- Different extinction ratios --- p.43
Chapter 4.4.2 --- Different AWG filter shape and bandwidth --- p.47
Chapter 4.5 --- Summary --- p.50
Chapter Chapter 5 --- Summary and Future Works --- p.51
Chapter 5.1 --- Summary of the thesis --- p.52
Chapter 5.2 --- Future works --- p.53
List of Publications --- p.55
BIBLIOGRAPHY --- p.56
Shieh, Bing-shun, i 謝炳順. "Dynamic Wavelength Allocation Scheme for Applications of Ethernet Passive Optical Networks". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/x8sewd.
Pełny tekst źródła國立中央大學
光電科學研究所碩士在職專班
96
This work proposes the dynamic wavelength allocation mechanism to solve the problem of sudden traffic loading for the Ethernet passive optical networks(PON). Ethernet PON has recently been considered as the most prospective application technology in access network. It is adopted the point-to-multi-point(P2MP) topology construction,Which can greatly reduce the amount of optical fiber and the disbursement. Moreover the DWA mechanism provides the bandwidth sharing across multiple physical PONs. A flexible new optical access solution is reached by combing the tunable lasers, the arrayed waveguide gratings, and the coarse/fine filters. The excellent stability of the network can bridge the gap between conventional TDM PONs and WDM PONs, and the powerful architecture is a promising candidate of the optical access networks for the next generation. This structure is composed of the single mode laser, the tunable laser, the array waveguide, and the buffer storage device. The probability model distribution is calculated by the MATLAB, and the mechanism of optimal separation is determined by the computer simulation. This system is tested through the measured reaction time or the flow capacity of network on campus network when the traffic load increases up to a loading level. It is shown that the DWA system, can effectively solve the problems when the load increases, Which is the most economical and simplest local network infrastructure for the PONs.
Chang, Ruey-Rong, i 張瑞榮. "The implementation of message passing Scheme and developing environment of Macro C". Thesis, 1990. http://ndltd.ncl.edu.tw/handle/68726057670432028234.
Pełny tekst źródłaChuen-Yi, Lin. "A New Credit-Based Dynamic Bandwidth Allocation Scheme for Ethernet Passive Optical Networks". 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0005-2906200613082300.
Pełny tekst źródłaLin, Chuen-Yi, i 林純儀. "A New Credit-Based Dynamic Bandwidth Allocation Scheme for Ethernet Passive Optical Networks". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/39581720346483782506.
Pełny tekst źródła中興大學
資訊科學系所
94
Ethernet Passive Optical Network (EPON) has been considered as a promising solution for next-generation broadband access networks due to its low cost, simplicity, and scalability. A critical issue of EPONs is bandwidth allocation of the shared upstream channel between end users. Some bandwidth allocation schemes based on interleaved polling have been proposed. However, none of them outperforms the others under all traffic loads. The credit-based scheme has an edge over the others in the case of light load, while the limited scheme prevails in the case of heavy load. We propose a new credit-based bandwidth allocation scheme that performs well under all traffic loads. In the proposed scheme, the size of the credit is dynamically determined by the OLT (Optical Line Terminal) according to each ONU''s (Optical Network Unit''s) traffic situation and the entire system load. Besides, the OLT has a maximum transmission window size limit for each ONU. Every ONU can transmit data up to the maximum window size per cycle. Simulation results verify that our proposed scheme has impressive performance under all traffic loads.
Lee, Li-an, i 李禮安. "Protecting User Privacy with Dynamic Identity-Based Scheme for Low-cost Passive RFID Tags". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/64576290045410787799.
Pełny tekst źródła國立交通大學
資訊科學與工程研究所
94
Radio Frequency Identification (RFID) is said to be the next generation bar code, which features contactless identification without visibility. We benefit greatly by adopting RFID in a variety of daily applications such as warehouse management, toll collection, library management, etc. However, RFID transmits data through radio frequency signals; therefore, attackers could analyze the radio frequency signals to acquire private data from users. If user privacy is not protected, users will be susceptible to personal identification and tracking by an adversary. User privacy may include data privacy and location privacy. To protect both of them, the output of tags must be encrypted and unpredictable. Furthermore, the acceptable cost of a passive RFID tag, which is no more than five cents, severely restricts the resources available for security. Schemes that protect user privacy in RFID applications are classified into three main categories: authentication, encryption, and dynamic identity. However, authentication-based schemes are easily broken. Because low-cost RFID tags do not contain tamper-resistant mechanisms, an adversary can steal the key for the authentication protocol. Encryption-based schemes can protect data privacy, but location privacy is still vulnerable since the ciphertext remains the same. Dynamic identity schemes are limited by exhaustive search problem, and the tag is still traceable in the period between identity updates. In this thesis, we proposed a feasible scheme based on one-way hash function for low-cost passive RFID tags. Each tag has a dynamic identity. Therefore the output of tag changes each time. We also proved that the scheme can protect both data privacy and location privacy against threats of replay attacks, eavesdropping, spoofing, man-in-the-middle attack, and message loss.
Chuang, Yo-Hsuan, i 莊祐軒. "A V2V-Based Fast Handoff Scheme Using IP Address Passing for Vehicular Ad-Hoc Networks". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/47731195931156909439.
Pełny tekst źródła國立高雄應用科技大學
資訊管理系
99
In VANETs, each vehicle should obtain an IP address for its identification before connecting to the Internet or getting some information from the Internet. Due to the rapid movement of vehicles, each vehicle must perform a handoff procedure between different access points. To ensure that the transmission of packets is not interrupted, the handoff scheme for VANETs is a key design issue. In view of this, we design a V2V-based fast handoff scheme using IP address passing for VANETs in this thesis. The proposed scheme allows a leaving vehicle in the exit area to pass an IP address which has been identified by the duplicate address detection (DAD) procedure to the vehicles in the entry area directly. In addition, the leaving vehicle in the exit area can also pass an IP address to the vehicles in the middle area if there is no vehicles in the entry area. Therefore, our scheme can reduce the use of Dynamic Host Configuration Protocol (DHCP) to obtain an IP address. Because DAD results in the largest delay of the whole DHCP procedure, our scheme can thus improve the utilization of IP address, reduce the time of acquiring an IP address, and reduce the whole handoff time.
Hassani, Hossein. "Microseismic event location and passive seismic imaging of crustal structures". 2019. https://tubaf.qucosa.de/id/qucosa%3A34788.
Pełny tekst źródła"A remodulation scheme for wavelength-division multiplexing passive optical network using time-interleaved differential phase shift keying modulation format". 2011. http://library.cuhk.edu.hk/record=b5894827.
Pełny tekst źródłaThesis (M.Phil.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (p. 60-66).
Abstracts in English and Chinese.
Chapter Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Overview of wavelength division multiplexed passive optical network (WDM-PON) and colorless optical network unit (ONU) --- p.1
Chapter 1.2 --- Implementation of colorless ONU --- p.4
Chapter 1.3 --- Rayleigh backscattering in WDM-PON --- p.6
Chapter 1.4 --- Motivation of this thesis --- p.9
Chapter 1.5 --- Outline of this thesis --- p.11
Chapter Chapter 2 --- Previous works of remodulation for WDM-PON --- p.12
Chapter 2.1 --- Introduction --- p.12
Chapter 2.2 --- Devices utilized by colorless ONU in remodulation schemes --- p.13
Chapter 2.2.1 --- Injection-locked Fabry-Perot laser diode at ONU --- p.13
Chapter 2.2.2 --- Reflective semiconductor optical amplifier --- p.15
Chapter 2.2.3 --- Reflective electro-absorption modulator and semiconductor optical amplifier (REAM-SOA) --- p.17
Chapter 2.3 --- Modulation methods in remodulation schemes --- p.18
Chapter 2.4 --- Summary --- p.23
Chapter Chapter 3 --- A remodulation scheme based on time-interleaved DPSK modulation format --- p.25
Chapter 3.1 --- Introduction --- p.25
Chapter 3.2 --- Operation principle: time-interleaving technology for phase-modulated signal --- p.27
Chapter 3.3 --- System architecture --- p.28
Chapter 3.4 --- Experimental results and discussion --- p.31
Chapter 3.5 --- Effect of timing misalignment on proposed remodulation scheme --- p.33
Chapter 3.6 --- Summary --- p.35
Chapter Chapter 4 --- Enhanced Tolerance to Rayleigh Backscattering in Remodulation Scheme Using Time-Interleaved DPSK Format --- p.37
Chapter 4.1 --- Introduction --- p.37
Chapter 4.2 --- Studies on Rayleigh backscattering suppression in optical domain --- p.39
Chapter 4.2.1 --- RB suppression in carrier-distributed schemes --- p.39
Chapter 4.2.2 --- RB suppression in remodulation schemes --- p.40
Chapter 4.2 --- Experimental setup and results --- p.42
Chapter 4.3 --- Discussion on RB suppression effect of the proposed scheme --- p.46
Chapter 4.3.1 --- Theoretical study and simulation results --- p.46
Chapter 4.3.2 --- Experimental demonstration of spectral relationship between signals and RB crosstalk --- p.49
Chapter 4.4 --- Summary --- p.53
Chapter Chapter 5 --- Conclusion and Future Works --- p.55
Chapter 5.1 --- Conclusion of this thesis --- p.55
Chapter 5.2 --- Future works --- p.57
List of Publications --- p.59
Bibliography --- p.60
Margueron, Xavier. "Elaboration sans prototypage du circuit équivalent de transformateurs de type planar". Phd thesis, 2006. http://tel.archives-ouvertes.fr/tel-00151063.
Pełny tekst źródłaAu long de ce mémoire, on apprend à représenter ces composants par un circuit équivalent et à identifier ce circuit équivalent par des mesures d'impédances. Compte tenu du grand nombre de paramètres ajustables, l'optimisation d'un tel transformateur serait compromise s'il fallait compter sur des simulations à éléments finis pour déduire les éléments du circuit équivalent. C'est pourquoi nous essayons de déduire, par des moyens analytiques, les éléments de ce circuit en partant des caractéristiques physiques et géométriques du composant. Le but est atteint pour tous les éléments du transformateur de fuites obtenus à l'aide d'un calcul original exploitant les formules de la méthode PEEC.
Nous étudions ensuite les problèmes posés par la mise en parallèle de spires, inévitable lorsqu'on veut faire circuler des centaines d'Ampères. Une approche analytique simple s'avère alors très efficace et, grâce à elle, la meilleure disposition des spires peut être recherchée à l'aide d'un logiciel de simulation de circuits de type PSpice.
Enfin, diverses solutions sont envisagées et testées par simulation fem pour réduire les pertes par courants induits dans les transformateurs et dans les conducteurs méplats. Le développement multipolaire du champ magnétique est largement mis à contribution pour mener ces études.
Hassan, Wan Hafiza Binti Wan. "Effects of enhancing performance in fiber-wireless networks". Thesis, 2015. https://vuir.vu.edu.au/30148/.
Pełny tekst źródła