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1
Hojný, Ondřej. „Evoluční návrh kombinačních obvodů“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442801.
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This diploma thesis deals with the use of Cartesian Genetic Programming (CGP) for combinational circuits design. The work addresses the issue of optimizaion of selected logic circuts, arithmetic adders and multipliers, using Cartesian Genetic Programming. The implementation of the CPG is performed in the Python programming language with the aid of NumPy, Numba and Pandas libraries. The method was tested on selected examples and the results were discussed.
2
Rogers, Derek. „Non-binary spread-spectrum multiple-access communications /“. Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phr725.pdf.
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3
Khalid, Abbas. „Coding for the multiple access binary channel“. Thesis, Lancaster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659445.
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Transmitting the maximum amount of information in minimum possible bandwidth is always desired . Multiple access (MA) communication is often used to achieve this objective. However, the mutual interference among the users handicaps the performance considerably. Addition of redundancy bits for reliable transmission demands more bandwidth. Power line communication (PLC) is considered an attractive candidate to overcome the scarcity of the bandwidth and the associated huge cost. PLC uses power lines as a communication medium which were originally designed for power distribution rather than data transmission and are more harsh compared to other communication media. Frequency-selective fading and inter-symbol-interference (ISI) due to multipaths degrade the bit error rate (BER) substantially. Furthermore, devices connected to the grid introduce impulsive noise on the network. Robust coding and modulation schemes are therefore required to increase the communication reliability. Multi-fold turbo coding is a technique used to improve the error performance of conventional turbo codes. Multi-fold turbo coding increases the randomness of a turbo code by dividing the long information sequence in small subsequences and making use of multiple pseudo random interleavers. Multiple interleavers spread the error burst over several symbols making the errors appear in random. Orthogonal frequency-division multiplex (OFDM) distributes the overall transmitted data in parallel on several orthogonal subcarriers and transforms a frequency-selective fading channel to a group of many flat-fading channels. OFDM possesses a unique property which disperses impulsive noise burst across its several sub-carriers; hence Abstract is able to cope better in an impulsive noise environment. This thesis presents multi-fold turbo coding scheme for MA channels. Specifically, a member of multi-fold family called two-fold has been adopted for the simplest MA channel, the two-user binary adder channel (2-BAC). Each user uses a distinct code to encode the information and the decoder employed uses iterative decoding to decode the received signal. Making use of distinct codes not only allows the correction of errors due to noise but also the correction of errors due to interference between users. Performance of multi-fold turbo codes has been evaluated under Gaussian and power-line conditions. Depedance of performance on number of iterations and blocklength is also presented. A simplified multipath model approach is introduced for complex power-line channels in which the power-line network is divided into number of small segments and each segment is considered as an independent sub-channel. Transfer function of each sub-channel is determined. The transfer function of the whole network is taken as a product of all component transfer functions. The approach has been applied to model two PLC networks that are used as reference channels for the work presented in the thesis. Multi-fold turbo codes can be modified to provide unequal error protection (UEP) levels to the information having different ranks of importance where the most significant information is protected more than the information with least importance. To demonstrate the practicality of the UEP mechanism for the 2-BAC, two test images are decomposed into luminance (£), saturation (8) and hue (if) components. The L component of each image is protected twice than the other two components. The performance of the modified multi-fold turbo codes is compared with the multi-fold turbo codes and conventional turbo codes in terms of pixel error rate (PER.) in Gaussian and power-line environments. The visual effects of PER. for each image are also presented.
4
Clarici, Georg. „Multiple quantum well binary-phase modulators : a feasibility study“. Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/458.
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5
Novak, Gregory S. „Simulated galaxy remnants produced by binary and multiple mergers /“. Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.
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Kubik, Lauren Ashley. „Simultaneously lifting multiple sets in binary knapsack integer programs“. Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1460.
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7
Crowley, William L. „Lossless compression using binary necklace classes and multiple huffman trees“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA397592.
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8
Benachour, Phillip. „Trellis decoding techniques for the multiple access binary adder channel“. Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314240.
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Merkl, Frank J. „Binary image compression using run length encoding and multiple scanning techniques /“. Online version of thesis, 1988. http://hdl.handle.net/1850/8309.
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10
Baxter, Rodney Charles. „The thermodynamics of binary liquid mixtures of compounds containing multiple bonds“. Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1016079.
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Excess thermodynamic properties have been determined for several binary liquid mixtures with the aim of testing various thermodynamic theories and postulates. Excess molar enthalpies, HEm, have been determined using an LKB flow microcalorimeter and excess molar volumes, VEm, have been determined using an Anton Paar vibrating tube densitometer. The activity coefficients at infinite dilution ƴ∞₁₃, have been determined using an atmospheric pressure gas-liquid chromatograph. The excess molar enthalpies and the excess molar volumes have been measured at 298.15 K for systems involving the bicyclic compounds decahydronaphthalene (decalin), 1,2,3,4-tetrahydronaphthalene (tetralin), bicyclohexyl, or cyclohexylbenzene mixed with 1- hexene, 1-hexyne, 1-heptene, 1-heptyne, cyclohexene, 1,3-cyclohexadiene, 1,4- cyclohexadiene, or benzene. These excess properties have also been measured for systems where the bicyclic compound has been replaced with benzene, cyclohexane or n-hexane. The results show defmite trends related to the size, shape, and the degree of unsaturation of the component molecules. The Flory theory has been used to predict excess molar enthalpies and excess molar volumes for {(a bicyclic compound or benzene or cyclohexane or n-hexane) +(an n-alkane or a 1-alkene or a 1-alkyne or a cycloalkane or cyclohexene or a cycloalkadiene or benzene)}. The one parameter equations offer reasonably good correlations between the predicted and the experimental results. More insight into the origins of the contnbutions to the excess thermodynamic properties for these systems has been gained by considering the approximate equations of Patterson and co-workers, which separate the interactional and the free volume contributions to the excess molar enthalpy and the excess molar volume. The one parameter equations have adequately rationalized a good deal of the observed behaviour for HEm and VEm. The theory of Liebermann and co-workers, which does not employ any adjustable parameters, has not been as successful at predicting the excess thermodynamic properties for the above systems. The activity coefficients at infinite dilution have been measured at 278.15 K, 288.15 K and 298.15 K for n-bexane, 1-bexene, 1-hexyne, n-heptane, 1-heptene, 1-heptyne, cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, and benzene, in decalin, tetralin, bicyclohexyl, and cyclohexylbenzene. Solvent losses from the column have been accounted for by an extrapolation procedure. The activity coefficient results together with the HEm and VEm values have been used to calculate the partial molar excess thermodynamic properties of mixing at infinite dilution. The partial molar excess properties at infinite dilution for decalin mixtures are similar to those for bicyclohexyl mixtures. There is also a similarity between the properties of the tetralin mixtures and the cyclohexylbenzene mixtures. The cycloalkadienes, benzene and the 1-alkynes exhibit a strong dissociation effect on being mixed with the saturated solvents, decalin and bicyclohexyl, but associate strongly with tetralin and with cyclohexylbenzene. The Flory theory bas been used to predict activity coefficients at infinite dilution from the experimentally determined HEm results for { (n-bexane or 1-hexene or 1-hexyne or naheptane or 1-heptene or 1-beptyne) + (a bicyclic compound)}. The theory is much better at predicting values for mixtures where both components are either saturated molecules or are unsaturated molecules than for {saturated + unsaturated} mixtures.
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Zhang, Qiaofu. „Use Diffusion Multiples to Investigate Diffusion and Precipitation Behavior in Binary Systems“. The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1483702959561522.
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12
Hu, Zhiguang, und 胡志光. „Binary latent variable modelling in the analysis of health data with multiple binary outcomes in an air pollution study in Hong Kong“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31237058.
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Hu, Zhiguang. „Binary latent variable modelling in the analysis of health data with multiple binary outcomes in an air pollution study in Hong Kong /“. Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19588975.
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14
Jiang, Fuhua. „SVM-Based Negative Data Mining to Binary Classification“. Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/cs_diss/8.
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The properties of training data set such as size, distribution and the number of attributes significantly contribute to the generalization error of a learning machine. A not well-distributed data set is prone to lead to a partial overfitting model. Two approaches proposed in this dissertation for the binary classification enhance useful data information by mining negative data. First, an error driven compensating hypothesis approach is based on Support Vector Machines (SVMs) with (1+k)-iteration learning, where the base learning hypothesis is iteratively compensated k times. This approach produces a new hypothesis on the new data set in which each label is a transformation of the label from the negative data set, further producing the positive and negative child data subsets in subsequent iterations. This procedure refines the base hypothesis by the k child hypotheses created in k iterations. A prediction method is also proposed to trace the relationship between negative subsets and testing data set by a vector similarity technique. Second, a statistical negative example learning approach based on theoretical analysis improves the performance of the base learning algorithm learner by creating one or two additional hypotheses audit and booster to mine the negative examples output from the learner. The learner employs a regular Support Vector Machine to classify main examples and recognize which examples are negative. The audit works on the negative training data created by learner to predict whether an instance is negative. However, the boosting learning booster is applied when audit does not have enough accuracy to judge learner correctly. Booster works on training data subsets with which learner and audit do not agree. The classifier for testing is the combination of learner, audit and booster. The classifier for testing a specific instance returns the learner's result if audit acknowledges learner's result or learner agrees with audit's judgment, otherwise returns the booster's result. The error of the classifier is decreased to O(e^2) comparing to the error O(e) of a base learning algorithm.
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Geoghegan, Mark. „IMPROVING THE DETECTION EFFICIENCY OF CONVENTIONAL PCM/FM TELEMETRY BY USING A MULTI-SYMBOL DEMODULATOR“. International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/607710.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaBinary PCM/FM has been widely adopted as a standard by the telemetry community. It offers a reasonable balance between detection efficiency and spectral efficiency, with very simple implementation in both the transmitter and receiver. Current technology, however, allows practical implementations of more sophisticated demodulators, which can substantially improve the detection efficiency of the waveform, with no changes to the modulator. This is accomplished by exploiting the memory inherent in the phase continuity of the waveform. This paper describes the implementation and performance of a noncoherent multi-symbol demodulator for PCM/FM. Sensitivity to offsets in carrier frequency, timing, and modulation index is also examined. Simulation results are presented which demonstrate improvements in detection efficiency of approximately 2.5 dB over traditional noncoherent single symbol detectors.
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Geoghegan, Mark. „EXPERIMENTAL RESULTS FOR MULTI-SYMBOL DETECTION OF PCM/FM“. International Foundation for Telemetering, 2001. http://hdl.handle.net/10150/607605.
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International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, NevadaIt has been previously shown, through computer simulations, that a multiple symbol detector can provide substantial gains in detection efficiency (nearly 3 dB) over traditional PCM/FM detectors. This is accomplished by performing correlations over multiple symbol intervals to take advantage of the memory inherent in the continuous phase PCM/FM signal. This paper presents measured hardware results, from a prototype developed for the Advanced Range Telemetry (ARTM) Project, that substantiate the previously published performance and sensitivity predictions. Furthermore, this work confirms the feasibility of applying this technology to high-speed commercial and military telemetry applications.
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Asar, Ozgur. „On Multivariate Longitudinal Binary Data Models And Their Applications In Forecasting“. Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614510/index.pdf.
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Longitudinal data arise when subjects are followed over time. This type of data is typically dependent, due to including repeated observations and this type of dependence is termed as within-subject dependence. Often the scientific interest is on multiple longitudinal measurements which introduce two additional types of associations, between-response and cross-response temporal dependencies. Only the statistical methods which take these association structures might yield reliable and valid statistical inferences. Although the methods for univariate longitudinal data have been mostly studied, multivariate longitudinal data still needs more work. In this thesis, although we mainly focus on multivariate longitudinal binary data models, we also consider other types of response families when necessary. We extend a work on multivariate marginal models, namely multivariate marginal models with response specific parameters (MMM1), and propose multivariate marginal models with shared regression parameters (MMM2). Both of these models are generalized estimating equation (GEE) based, and are valid for several response families such as Binomial, Gaussian, Poisson, and Gamma. Two different R packages, mmm and mmm2 are proposed to fit them, respectively. We further develop a marginalized multilevel model, namely probit normal marginalized transition random effects models (PNMTREM) for multivariate longitudinal binary response. By this model, implicit function theorem is introduced to explicitly link the levels of marginalized multilevel models with transition structures for the first time. An R package, bf pnmtrem is proposed to fit the model. PNMTREM is applied to data collected through Iowa Youth and Families Project (IYFP). Five different models, including univariate and multivariate ones, are considered to forecast multivariate longitudinal binary data. A comparative simulation study, which includes a model-independent data simulation process, is considered for this purpose. Forecasting independent variables are taken into account as well. To assess the forecasts, several accuracy measures, such as expected proportion of correct prediction (ePCP), area under the receiver operating characteristic (AUROC) curve, mean absolute scaled error (MASE) are considered. Mother's Stress and Children'
s Morbidity (MSCM) data are used to illustrate this comparison in real life. Results show that marginalized models yield better forecasting results compared to marginal models. Simulation results are in agreement with these results as well.
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陳子健 und Chi-kin John Baptist Chan. „A study of binary sequences for direct-sequence spread-spectrum multiple-access communication systems“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31212761.
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Chan, Chi-kin John Baptist. „A study of binary sequences for direct-sequence spread-spectrum multiple-access communication systems /“. Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B16043005.
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20
Cardoso, Catia Vanessa Varejao. „Observational properties of brown dwarfs : the low-mass end of the mass function“. Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3592.
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Brown dwarfs are objects with sub-stellar masses that are unable to sustain hydrogen burning, cooling down through out their lifetimes. This thesis presents two projects, the study of the IMF of the double cluster, h & χ Persei, and the determination of the dynamical masses of the brown dwarf binary, ε Indi Ba, Bb. The study of a cluster’s population distribution gives us the opportunity to study a statistically meaningful population of objects over a wide range of masses (from massive stars to brown dwarfs), with a similar age and chemical composition providing formation and dynamical evolution constraints. h & χ Persei is the largest double cluster known in our galaxy. Using optical and infrared photometric data we have produced the deepest mass function for the system. A study of the radial distribution shows evidence of mass segregation while the mass function shows that these clusters may be suffering from accelerated dynamical evolution due to their interaction, triggering the ejection of brown dwarfs. The physical parameterization of brown dwarfs is reliant on the use of interior and atmospheric models. The study of brown dwarf binaries can provide crucial model independent measurements, especially masses. ε Indi Ba, Bb (spectral types T1 and T6) is the closest known brown dwarf binary to Earth. The brown dwarf binary itself orbits a main sequence star allowing us to constrain the distance, metallicity and age of the system making it possible to break the sub-stellar mass-age-luminosity degeneracy. The relative motion of the brown dwarf binary has been studied with precision astrometry from infrared AO data, allowing the determination of the system mass, 121.16 ± 0.17 ± 1.08 MJup . The individual masses of the binary components were derived from the absolute movement of the binary to be MBa = 68.04±0.94 MJup and MBb = 53.12±0.32 MJup. We concluded that the isochronally-derived masses were underestimating the system mass by ∼ 60%, due to the likely underestimation of the age of the system. The evolutionary models are consistent with the parameters measured observationally if the system has an age ∼ 4 Gyr.
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Niu, Yue S., Ning Hao und Heping Zhang. „Multiple Change-Point Detection: A Selective Overview“. INST MATHEMATICAL STATISTICS, 2016. http://hdl.handle.net/10150/622820.
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Very long and noisy sequence data arise from biological sciences to social science including high throughput data in genomics and stock prices in econometrics. Often such data are collected in order to identify and understand shifts in trends, for example, from a bull market to a bear market in finance or from a normal number of chromosome copies to an excessive number of chromosome copies in genetics. Thus, identifying multiple change points in a long, possibly very long, sequence is an important problem. In this article, we review both classical and new multiple change-point detection strategies. Considering the long history and the extensive literature on the change-point detection, we provide an in-depth discussion on a normal mean change-point model from aspects of regression analysis, hypothesis testing, consistency and inference. In particular, we present a strategy to gather and aggregate local information for change-point detection that has become the cornerstone of several emerging methods because of its attractiveness in both computational and theoretical properties.
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Kocakanat, Murat. „A direct sequence - code division multiple access/binary phase shift keying (DS-CDMA/BPSK) modem design“. Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/8270.
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Griot, Miguel. „Nonlinear codes for multiple access to binary channels and higher-order modulations over the AWGN channel“. Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1693067891&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Rakkarn, Sakchai. „OPERATION ASSIGNMENT WITH BOARD SPLITTING AND MULTIPLE MACHINES IN PRINTED CIRCUIT BOARD ASSEMBLY“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1201021027.
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Bailey, Brittney E. „Data analysis and multiple imputation for two-level nested designs“. The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531822703002162.
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Tchangnwa, Nya Fridolin. „Transition fluide-verre et verres multiples dans les suspensions colloïdales par la théorie du couplage de mode : rôle de la structure statique“. Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1161.
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La théorie de couplage de mode (MCT) est l'une des méthodes les plus utilisées pour étudier les transitions vitreuses dans les fluides classiques. Ses prédictions sont en général en accord semi quantitatif avec les simulations. Sa mise en oeuvre nécessite la détermination de la structure statique, généralement par résolution des équations d'Orsntein-Zernike avec une fermeture adéquate. Partant de fermetures utilisant des fonctions « bridges » déduites de la fonctionnelle de référence du mélange de sphères dures, notre travail a consisté d'abord à étudier l'influence de la qualité de cette structure statique sur les prédictions relatives aux états non ergodiques dans des mélanges binaires dissymétriques. Nous avons ensuite considéré les résultats de la théorie du couplage de modes dans sa version naïf (NMCT ) et complète, afin d'analyser les mécanismes d'arrêt, les comparer au fluide effectif et aux approches stochastiques (équations de Langevin généralisées). Enfin, nous proposons une version pragmatique de cette méthode qui fournit des prédictions en meilleur accord quantitatif avec les résultats des simulations pour une variété de potentiels d'interactionThe mode coupling theory (MCT) is one of the most widely used methods for studying the glass transition in classical fluids. Its predictions are usually in semi-quantitative agreement with simulation. Its implementation requires the determination of the static structure usually from the Ornstein-Zernike equations with a suitable closure. Starting from closures that use bridge functions deduced from the hard-sphere reference functional, our work consisted first in studying the influence of the quality of this static structure on the predictions concerning the non-ergodic states in asymmetric binary mixtures. We next considered the results of the mode coupling theory in its naive and full versions, in order to analyze the arrest mechanisms and compare them to the effective fluid and the stochastic approaches (generalized Langevin equations). Finally, we propose a pragmatic version of this method that provides predictions in better quantitative agreement with simulations for a variety of interaction potentials
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Basudhar, Anirban. „Computational Optimal Design and Uncertainty Quantification of Complex Systems Using Explicit Decision Boundaries“. Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/201491.
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This dissertation presents a sampling-based method that can be used for uncertainty quantification and deterministic or probabilistic optimization. The objective is to simultaneously address several difficulties faced by classical techniques based on response values and their gradients. In particular, this research addresses issues with discontinuous and binary (pass or fail) responses, and multiple failure modes. All methods in this research are developed with the aim of addressing problems that have limited data due to high cost of computation or experiment, e.g. vehicle crashworthiness, fluid-structure interaction etc.The core idea of this research is to construct an explicit boundary separating allowable and unallowable behaviors, based on classification information of responses instead of their actual values. As a result, the proposed method is naturally suited to handle discontinuities and binary states. A machine learning technique referred to as support vector machines (SVMs) is used to construct the explicit boundaries. SVM boundaries can be highly nonlinear, which allows one to use a single SVM for representing multiple failure modes.One of the major concerns in the design and uncertainty quantification communities is to reduce computational costs. To address this issue, several adaptive sampling methods have been developed as part of this dissertation. Specific sampling methods have been developed for reliability assessment, deterministic optimization, and reliability-based design optimization. Adaptive sampling allows the construction of accurate SVMs with limited samples. However, like any approximation method, construction of SVM is subject to errors. A new method to quantify the prediction error of SVMs, based on probabilistic support vector machines (PSVMs) is also developed. It is used to provide a relatively conservative probability of failure to mitigate some of the adverse effects of an inaccurate SVM. In the context of reliability assessment, the proposed method is presented for uncertainties represented by random variables as well as spatially varying random fields.In order to validate the developed methods, analytical problems with known solutions are used. In addition, the approach is applied to some application problems, such as structural impact and tolerance optimization, to demonstrate its strengths in the context of discontinuous responses and multiple failure modes.
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Benbakoura, Mansour. „Evolution des étoiles de faible masse en interaction : observations multi-techniques et modélisation des systèmes multiples“. Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7027.
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Cette thèse est consacrée à l'étude des étoiles de faible masse ayant dans leur environnement proche d'autres étoiles ou des planètes. Nous nous sommes concentrés sur l'influence des interactions avec ces compagnons sur l'évolution stellaire ainsi que leurs conséquences observables.Dans la première partie, nous présentons le modèle d'évolution des systèmes étoile–planète que nous avons développé au cours de cette thèse, nommé ESPEM (Évolution des Systèmes Planétaires Et Magnétisme). Ce modèle prend en compte de façon ab-initio des effets du vent stellaire magnétisé et de la dissipation de marée sur la rotation stellaire et l'orbite planétaire, simultanément avec l'évolution structurelle de l'étoile. Premièrement, nous l'utilisons pour étudier l'évolution séculaire de la rotation des étoiles hôtes de systèmes planétaires et montrons notamment que cette évolution peut être significativement différente de celle des étoiles isolées. Ensuite, nous examinons les prédictions de ce modèle concernant l'architecture orbitale des systèmes étoile–planète. Nos résultats suggèrent une interprétation aux distributions de périodes orbitales et de de rotation stellaire observées.Dans la deuxième partie, nous montrons en quoi l'observation d'étoiles binaires évoluées permet de tester les théories astrophysiques, notamment l'astérosismologie et l'interaction de marée. Dans un premier temps, nous présentons les résultats d'un programme d'observations que nous avons mené pendant plus de deux ans et qui nous a permis de caractériser 16 systèmes binaires à éclipses. Ensuite, nous comparons ces résultats avec ceux que nous avons obtenus en analysant cet échantillon à l'aide d'outils astérosismiques dans le but de vérifier l'exactitude de ces derniers. Enfin, en élargissant l'échantillon étudié à 30 autres étoiles binaires évoluées, nous testons la théorie de l'évolution de marée. Ceci nous permet à la fois de valider la théorie et de comprendre l'évolution des systèmes observés dans ce travail.Ce travail met en avant deux aspects de la spécificité des systèmes multiples. Premièrement, il montre en quoi l'évolution des étoiles est impactée par la présence d'un compagnon stellaire ou planétaire. Deuxièmement, il met en avant l'intérêt des étoiles binaires pour tester les théories astrophysiques et renforce la compréhension actuelle de l'évolution stellaireThis thesis is devoted to the study of low-mass stars having other stars or planets in their immediate environment. We focused on the influence of interactions with these companions on stellar evolution and their observable consequences.In the first part, we present the model of evolution of star–planet systems that we developed during this thesis, called ESPEM (French acronym for Evolution of Planetary Systems and Magnetism). This model incorporates ab-initio prescriptions to quantify the effects of magnetized stellar wind and tidal dissipation on stellar rotation and planetary orbit, simultaneously with the star's structural evolution. First, we use it to study the secular evolution of the rotation of planet-host stars and show that this evolution can be significantly different from that of isolated stars. Next, we examine the predictions of this model regarding the orbital architecture of star–planet systems. Our results suggest an interpretation to the observed distributions of orbital and stellar rotation periods.In the second part of the manuscript, we show how the observation of advanced binary stars allows us to test astrophysical theories, in particular asteroseismology and tidal interaction. First, we present the results of an observation program that we conducted for more than two years and that allowed us to characterize 16 eclipsing binary systems. Then, we compare these results with those obtained by analyzing this sample using asteroseismic tools to verify the accuracy of the latter. Finally, by extending the studied sample to 30 other advanced binary stars including an evolved primary, we test the theory of tidal evolution. This allows us both to validate the theory and to understand the evolution of the systems observed in this work.This work highlights two aspects of the specificity of multiple systems. First, it shows how the evolution of stars is affected by the presence of a stellar or planetary companion. Second, it emphasizes the interest of binary stars in testing astrophysical theories and reinforces the current understanding of stellar evolution
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Edjeou, René Tchalim. „Contribution à la réalisation d'un dispositif à transport acoustique de charges“. Valenciennes, 1999. https://ged.uphf.fr/nuxeo/site/esupversions/f6344825-6189-4bcd-a9c7-83534f301ffe.
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Dans ce mémoire nous présentons une étude depuis la modélisation jusqu'à la réalisation et la caractérisation d'un dispositif de transport acoustique de charges base sur une structure hemt de la filière de l'arséniure de gallium (GaAs). Bénéficiant des propriétés semi-conductrice et piézoélectrique du GaAs, le dispositif utilise une onde acoustique de surface, générée et détectée directement par un transducteur à peignes interdigites, pour confiner et transporter les charges dans un canal à proximité de la surface. Après un rappel des caractéristiques des ondes acoustiques de surface (génération, propagation et détection) dans les hétéro structures piézoélectriques, nous avons exposé les bases physiques et le principe de fonctionnement de transport acoustique de charges. L’étude s'inscrit dans la perspective de la réalisation de circuits monolithiques à caractère innovant qui permet l'intégration sur un même substrat, d'autres composants. Nous développons, à partir d'un modèle de simulation bidimensionnelle, une analyse des phénomènes de transport de charge dans les hétéros structures. Ce modèle théorique est basé sur la résolution des équations fondamentales des semi-conducteurs déduites des équations de Poisson, de continuités et de densités de courant, pour les électrons et les trous. Basés sur ces études, nous avons mis au point les différentes étapes technologiques et réalisé deux prototypes a 178 MHz. Les mesures effectuées ont permis de vérifier la fréquence centrale de propagation de l'onde acoustique et les temps de retard, de déterminer les pertes d'insertions et les impédances des transducteurs, et enfin de confirmer le transport acoustique d'un signal injecte. Enfin sont présentés deux types de circuits mixtes : un modulateur multi-puits quantiques spatial bidimensionnel et un filtre transversal programmable, en cours de développement au laboratoire, pour répondre aux besoins des processeurs de signaux de haute vitesse utilisés dans les systèmes de communication moderne et radars.
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Tlich, Mohamed. „Augmentation des performances des systèmes DSL par allocation dynamique de spectre“. Phd thesis, Télécom ParisTech, 2006. http://pastel.archives-ouvertes.fr/pastel-00001889.
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Les systèmes DSL sont des technologies de transmission qui transportent des flux de données importants sur de simples lignes téléphoniques. Malheureusement, plusieurs phénomènes perturbateurs sont susceptibles de dégrader la qualité des liaisons. Les limitations sont principalement dues à l'affaiblissement ainsi qu'à des problèmes de compatibilité électromagnétique. Dans ce contexte, ce travail de thèse consiste à augmenter les performances marge de bruit/débit/portée des systèmes DSL par allocation dynamique de spectre (DSM: Dynamic Spectrum Management). Dans une première partie sont développées trois méthodes d'allocation discrète de bits entre les porteuses d'un système DSL à modulation DMT. La première est une simplification importante de l'algorithme de P.S. Chow à distribution plate d'énergie. La deuxième étant un processus de moindre complexité qui nous ramène à la distribution optimale d'énergie entre les porteuses, appelé "remplissage par Gammas croissants". Et la troisième est une méthode d'attribution de marges de bruit distinctes aux différents flux d'une même liaison DSL. Après cette amélioration de la technologie de transmission DSL qui constitue le niveau 0 de la DSM, l'atténuation de l'interférence entre les lignes d'un même câble DSL par allocation coordonnée de spectre (niveau 2 de la DSM) est abordée, et deux procédés sont proposés. Le premier est un procédé de réglage dynamique des DSP des porteuses les unes indépendamment des autres, de façon à réduire l'interférence provenant de certaines lignes dont le débit est supérieur au débit nécessaire aux services. Le deuxième procédé est une nouvelle architecture DSL, caractérisée par l'introduction d'éléments actifs dans la sous-répartition. Les performances des lignes, divisées en deux tronçons plus courts et séparés, sont ainsi améliorées. Dans une dernière partie est considérée la transmission vectorielle qui constitue le troisième niveau de la DSM. Des méthodes d'annulation d'interférence entre les lignes d'un même câble DSL sont présentées, et un modèle de détermination de la matrice de canal MIMO est développé.
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Schneider, Sebastian Olivier [Verfasser], Marcela [Akademischer Betreuer] Ibanez, Marcela [Gutachter] Ibanez, Martin [Gutachter] Schlather und Stephan [Gutachter] Klasen. „Advances and Applications of Experimental Measures to Test Behavioral Saving Theories and a Method to Increase Efficiency in Binary and Multiple Treatment Assignment / Sebastian Olivier Schneider ; Gutachter: Marcela Ibanez, Martin Schlather, Stephan Klasen ; Betreuer: Marcela Ibanez“. Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1149954671/34.
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Schneider, Sebastian O. [Verfasser], Marcela [Akademischer Betreuer] Ibanez, Marcela [Gutachter] Ibanez, Martin [Gutachter] Schlather und Stephan [Gutachter] Klasen. „Advances and Applications of Experimental Measures to Test Behavioral Saving Theories and a Method to Increase Efficiency in Binary and Multiple Treatment Assignment / Sebastian Olivier Schneider ; Gutachter: Marcela Ibanez, Martin Schlather, Stephan Klasen ; Betreuer: Marcela Ibanez“. Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1149954671/34.
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Huang, Shijie. „Waiting Lines and System Selection in Constrained Service Systems with Applications in Election Resource Allocation“. The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471541297.
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Pires, Daniela Maria Carvoeiro de Jesus. „Determinantes da confianca dos consumidores : evidência para Portugal entre 1998 e 2017“. Master's thesis, Instituto Superior de Economia e Gestão, 2018. http://hdl.handle.net/10400.5/16888.
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Mestrado em Métodos Quantitativos para a Decisão Económica e EmpresarialOs Inquéritos Qualitativos de Conjuntura às Empresas e aos Consumidores são elementos indispensáveis para apreender os aspetos económicos que não são diretamente quantificáveis. Estes inquéritos são importantes complementos às estatísticas quantitativas oficiais para detetar momentos de viragem no ciclo económico. A confiança dos consumidores é, assim, um tema essencial para a análise da atividade económica. Elaborou-se uma análise da sensibilidade do indicador de confiança dos consumidores aos ciclos da economia nacional, com base em modelos de regressão para dados mensais e trimestrais, que incluem variáveis explicativas relacionadas com indicadores macroeconómicos, políticos e sociais. Concluiu-se que os consumidores são mais sensíveis a fatores macroeconómicos com maior exposição mediática, como o desemprego e a informação sobre o comportamento do PIB.
The Conjunctural Qualitative Surveys conducted on Corporations and Consumers are considered essential elements to assess and apprehend the aspects of the economy which are not directly quantifiable. These surveys are important for detecting turning points in the economic cycle. Consumer Confidence is an important indicator when analysing the economic activity. Considering this, a sensitivity analysis was conducted of the Consumer Confidence Index to the national economy cycles, based on regression models with explanatory variables related to macroeconomic, political and social indicators which are considered relevant events. To summarize, consumers are more sensitive to macroeconomic factors with greater exposure to the media, such as unemployment and information on GDP.
info:eu-repo/semantics/publishedVersion
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Sarrazin-Baudoux, Christine. „Etude du mixage ionique dans un système à grande limite de solubilité : cas du Cuivre-Nickel, caractérisation de l'adhérence de ces revêtements sur substrat acier“. Poitiers, 1987. http://www.theses.fr/1987POIT2305.
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Elaboration de la technique de melange ionique associant l'evaporation de couches minces successives et l'implantation ionique. Etude du melange ionique des multicouches cu-ni. Mise en evidence de deux phenomenes principaux de diffusion en fonction de la temperature. Analyse des phases formees lors du melange ionique. Application de la technique de melange ionique comme procede de depot
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Raghavan, Deepak. „A Survey of Stellar Families: Multiplicity of Solar-type Stars“. unrestricted, 2009. http://etd.gsu.edu/theses/available/etd-04212009-165714/.
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Thesis (Ph. D.)--Georgia State University, 2009.Title from file title page. Harold A. McAlister, committee chair; Russel J. White, Brian D. Mason, Douglas R. Gies, David W. Latham, A.G. Unil Perera, Todd J. Henry, committee members. Description based on contents viewed Aug. 24, 2009. Includes bibliographical references (p. 391-410).
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Matos, Luís Miguel de Oliveira. „Lossless compression algorithms for microarray images and whole genome alignments“. Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14273.
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Doutoramento em InformáticaNowadays, in the 21st century, the never-ending expansion of information is a major global concern. The pace at which storage and communication resources are evolving is not fast enough to compensate this tendency. In order to overcome this issue, sophisticated and efficient compression tools are required. The goal of compression is to represent information with as few bits as possible. There are two kinds of compression, lossy and lossless. In lossless compression, information loss is not tolerated so the decoded information is exactly the same as the encoded one. On the other hand, in lossy compression some loss is acceptable. In this work we focused on lossless methods. The goal of this thesis was to create lossless compression tools that can be used in two types of data. The first type is known in the literature as microarray images. These images have 16 bits per pixel and a high spatial resolution. The other data type is commonly called Whole Genome Alignments (WGA), in particularly applied to MAF files. Regarding the microarray images, we improved existing microarray-specific methods by using some pre-processing techniques (segmentation and bitplane reduction). Moreover, we also developed a compression method based on pixel values estimates and a mixture of finite-context models. Furthermore, an approach based on binary-tree decomposition was also considered. Two compression tools were developed to compress MAF files. The first one based on a mixture of finite-context models and arithmetic coding, where only the DNA bases and alignment gaps were considered. The second tool, designated as MAFCO, is a complete compression tool that can handle all the information that can be found in MAF files. MAFCO relies on several finite-context models and allows parallel compression/decompression of MAF files.
Hoje em dia, no século XXI, a expansão interminável de informação é uma grande preocupação mundial. O ritmo ao qual os recursos de armazenamento e comunicação estão a evoluir não é suficientemente rápido para compensar esta tendência. De forma a ultrapassar esta situação, são necessárias ferramentas de compressão sofisticadas e eficientes. A compressão consiste em representar informação utilizando a menor quantidade de bits possível. Existem dois tipos de compressão, com e sem perdas. Na compressão sem perdas, a perda de informação não é tolerada, por isso a informação descodificada é exatamente a mesma que a informação que foi codificada. Por outro lado, na compressão com perdas alguma perda é aceitável. Neste trabalho, focámo-nos apenas em métodos de compressão sem perdas. O objetivo desta tese consistiu na criação de ferramentas de compressão sem perdas para dois tipos de dados. O primeiro tipo de dados é conhecido na literatura como imagens de microarrays. Estas imagens têm 16 bits por píxel e uma resolução espacial elevada. O outro tipo de dados é geralmente denominado como alinhamento de genomas completos, particularmente aplicado a ficheiros MAF. Relativamente às imagens de microarrays, melhorámos alguns métodos de compressão específicos utilizando algumas técnicas de pré-processamento (segmentação e redução de planos binários). Além disso, desenvolvemos também um método de compressão baseado em estimação dos valores dos pixéis e em misturas de modelos de contexto-finito. Foi também considerada, uma abordagem baseada em decomposição em árvore binária. Foram desenvolvidas duas ferramentas de compressão para ficheiros MAF. A primeira ferramenta, é baseada numa mistura de modelos de contexto-finito e codificação aritmética, onde apenas as bases de ADN e os símbolos de alinhamento foram considerados. A segunda, designada como MAFCO, é uma ferramenta de compressão completa que consegue lidar com todo o tipo de informação que pode ser encontrada nos ficheiros MAF. MAFCO baseia-se em vários modelos de contexto-finito e permite compressão/descompressão paralela de ficheiros MAF.
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Babinec, Adam. „Monitorování dopravy z leteckých videí“. Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-264938.
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This thesis proposes a system for extraction of vehicle trajectories from aerial video data for traffic analysis. The system is designed to analyse video sequence of a single traffic scene captured by an action camera mounted on an arbitrary UAV flying at the altitudes of approximately 150 m. Each video frame is geo-registered using visual correspondence of extracted ORB features. For the detection of vehicles, MB-LBP classifier cascade is deployed, with additional step of pre-filtering of detection candidates based on movement and scene context. Multi-object tracking is achieved by Bayesian bootstrap filter with an aid of the detection algorithm. The performance of the system was evaluated on three extensively annotated datasets. The results show that on the average, 92% of all extracted trajectories are corresponding to the reality. The system is already being used in the research to aid the process of design and analysis of road infrastructures.
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Alcober, Jesús. „Aportación al estudio de protocolos de acceso múltiple: El protocolo ALOHA estabilizado de ventana“. Doctoral thesis, Universitat Politècnica de Catalunya, 1997. http://hdl.handle.net/10803/7035.
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Aquesta tesi presenta una nova família de protocols basats en contesa, els algorismes ALOHA estabilitzats de finestra (window stabilized ALOHA, WSA). Aquests protocols d'accés aleatori tenen resolució dinàmica i probabilística i es poden seguir aplicant encara que el model de Poisson para el procés d'arribades no sigui vàlid. De partida, s'ha conjuntat la idea simple dels protocols ALOHA, amb l'eficiència dels protocols de resolució de col·lisions amb accés bloquejat, resultant una nova família de protocols que tenen unes prestacions millorades respecte als existents amb el mateix model de sistema.
Aquests protocols presentats i analitzats són una variant millorada del protocol Slotted-ALOHA estabilitzat, proposat per nombrosos autors, que aconseguien d'aquesta forma que l'algorisme arribés de forma estable a aconseguir un throughput de 0,36.
El càlcul analític dels seus paràmetres: throughput i retard, permet quantificar la bondat d'aquests algorismes i comparar-los amb els ja existents.
Els algorismes presentats aquí aconsegueixen un throughput de 0,4335 per al cas del feedback binari, 0,4365 per al cas del feedback ternario, i de 0,5052 per a un feedback òptim.
Esta tesis presenta una nueva familia de protocolos basados en contienda, los algoritmos ALOHA estabilizados de ventana (window stabilized ALOHA, WSA). Estos protocolos de acceso aleatorio tienen resolución dinámica y probabilística y se pueden seguir aplicando aún cuando el modelo de Poisson para el proceso de llegadas no sea válido.
De partida, se ha aunado la idea simple de los protocolos ALOHA, con la eficiencia de los protocolos de resolución de colisiones con acceso bloqueado, resultando una nueva familia de protocolos que tienen unas prestaciones mejoradas respecto a los existentes con el mismo modelo de sistema.
Estos protocolos presentados y analizados son una variante mejorada del protocolo Slotted-ALOHA estabilizado, propuesto por numerosos autores, que conseguían de esta forma que el algoritmo llegara de forma estable a conseguir un throughput de 0,36.
El cálculo analítico de sus parámetros: throughput y retardo, permite cuantificar la bondad de estos algoritmos y compararlos con los ya existentes.
Los algoritmos presentados aquí consiguen un throughput de 0,4335 para el caso del feedback binario, 0,4365 para el caso del feedback ternario, y de 0,5052 para un feedback óptimo.
This thesis introduces a new family of content-based protocols , the window stabilized ALOHA algorithms (WSA). These random access protocols have dynamic and probabilistic resolution and they can be applied even when the Poisson model for the arrival process would not be valid.
Initially, it has brought together the simple idea of ALOHA protocols , with the efficiency of the collision resolution protocols with blocked access , resulting in a new family of protocols that have improved performance with respect to the existing ones with the same system model.
These protocols are a improved variant protocol of Slotted-stabilized ALOHA , proposed by many authors, who get in this way that the algorithm arrive at the stable throughput of 0.36.
The analytical calculation of parameters, throughput and delay, allows quantify the goodness of these algorithms and compare them with existing ones.
The algorithms presented here provide a throughput of 0.4335 to the case of binary feedback, 0.4365 to the case of ternary feedback, and 0.5052 to optimal feedback.
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Voll, Sarah. „Functional Genetic Analysis Reveals Intricate Roles of Conserved X-box Elements in Yeast Transcriptional Regulation“. Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30168.
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Understanding the functional impact of physical interactions between proteins and
DNA on gene expression is important for developing approaches to correct disease-associated gene dysregulation. I conducted a systematic, functional genetic analysis of protein-DNA interactions in the promoter region of the yeast ribonucleotide reductase
subunit gene RNR3. I measured the transcriptional impact of systematically
perturbing the major transcriptional regulator, Crt1, and three X-box sites on the
DNA known to physically bind Crt1. This analysis revealed interactions between
two of the three X-boxes in the presence of Crt1, and unexpectedly, a significant
functional role of the X-boxes in the absence of Crt1. Further analysis revealed Crt1-
independent regulators of RNR3 that were impacted by X-box perturbation. Taken
together, these results support the notion that higher-order X-box-mediated interactions
are important for RNR3 transcription, and that the X-boxes have unexpected roles in the regulation of RNR3 transcription that extend beyond their interaction with Crt1.
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Ollivier, Benjamin. „Acoustique longue portée pour transmission et localisation de signaux“. Thesis, Télécom Bretagne, 2016. http://www.theses.fr/2016TELB0413/document.
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Le positionnement d'objets sous-marins représente un enjeu stratégique pour des applications militaires, industrielles et scientifiques. Les systèmes de positionnement reposent sur des signaux de type SONAR « Sound Navigation and Ranging ». Plusieurs émetteurs synchrones avec des temps d'émission connus sont alors considérés, l'objectif étant que la position d'un récepteur se fasse en fonction des positions des émetteurs. Nous avons la main mise sur la détection des signaux en réception d'une part, et sur le choix des formes d'ondes à l'émission d'autre part. La méthode de détection, basée sur le filtrage adapté, se veut robuste aux différentes perturbations engendrées par le canal de propagation (pertes par transmission, multi-trajets) et par le système lui-même (environnement multi-émetteurs). De plus, la détection restreinte à une somme de tests d'hypothèses binaires, nécessite un fonctionnement en temps réel. A l'émission, les formes d'ondes doivent permettre d'identifier indépendamment les émetteurs les uns des autres. Ainsi les travaux portent essentiellement sur les modulations FHSS, les paramètres de construction de ces signaux étant alors choisis de sorte à optimiser la méthode de détection étudiée. Enfin, l'implémentation des algorithmes issus de ces travaux sur des systèmes embarqués a permis leur validation sur des données enregistrées, puis en conditions réelles. Ces essais ont été réalisés avec l'entreprise ALSEAMAR, dans le cadre de la thèse CIFRE-DGAThere is an increasing interest in underwater positioning system in industry (off-shore, military, and biology). In order to localize a receiver relative to a grid of transmitters, thanks to the knowledge of positions and transmission time, it needs to detect each signal and estimate the TOA (Time Of Arrival). Thus, a range between a transmitter and receiver can be deduced by estimation of TOA. When receiver knows three ranges at least, it can deduce its position by triangulation. This work takes into account signal detection, and waveform choice. Detection method, based on matched filter, needs to be robust face to propagation channel (transmission loss, multi-paths) and to the system (multi-users environment). Moreover, the detection structure, being a combination of binary hypothesis testing, must work in real time. In a CDMA context which requires to distinguish each transmitter, the FHSS (Frequency Hopped Spread Spectrum) modulation, allocating one code per user, is adapted. FHSS signals performance, depending of the number of frequency shifts N and the time-bandwidth product, are analyzed from detection criterion point of view. Moreover, detection method and adapted signal is tested in a shallow water environment.The research was supported by ALSEAMAR and DGA-MRIS scholarship
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Jeangoudoux, Clothilde. „Génération automatique de tests logiciels dans le contexte de la certification aéronautique“. Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS148.
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Ces travaux de thèse s'inscrivent dans le contexte de la validation et vérification de logiciels numériques dans pour la certification aéronautique. Dans cette thèse, nous proposons une solution de génération automatique de tests numériques fiables qui respectent les règles de développement imposées par le processus de certification. Les tests, composés de stimulations associées à un comportement attendu, sont ainsi générés à partir d'une spécification du comportement fonctionnel du logiciel. Valider le logiciel par le test revient à lui donner les stimulations en entrée et comparer le résultat obtenu (binaire) au comportement déterminé à l'aide de la spécification fonctionnelle (décimal). La solution proposée utilise la programmation par contraintes (numériques) et une méthode combinatoire de résolution en domaine continu (intervalles) pour construire un pavage de l'espace réalisable par des boîtes intérieures (ne contenant que des solutions) et des boîtes frontières englobant généralement la frontière de la zone réalisable. L'ensemble des tests est ensuite élaboré à l'aide du test par mutation sur les contraintes, qui permet d'évaluer la qualité de la campagne de test courante et d'ajouter de nouveaux tests si nécessaire. Les conversions entre les formats binaires et décimaux sont inévitables et introduisent des erreurs de calculs pouvant avoir un impact sur la fiabilité des résultats des tests. Nous renforçons notre solution grâce à l'utilisation et le développement d'arithmétiques fiables (arithmétique d'intervalles décimale multi-précision et arithmétique en bases mixtes binaire/décimale)This work is done in the context of the validation and verification of numerical software for aircraft certification. In this thesis we develop an automatic generator of relaiable numerical test, according to the development rules mandated by the certification process. The tests, composed of stimulations associated with an expected behavior, are thus generated from a specification of the functional behavior of the software. Validation by test of the software means that given the simultations are inputs of the software, we compare the obtained result (binary) with the expected behavior identified using the functional specification (decimal). This work uses Constraint Programming (numerical constraints) and a combinatorial method of continuous domain resolution (intervals) to construct a paving of the feasible set by inner boxes (containing only solutions) and outer boxes encompassing the boundary of the feasible region. All tests are then developed using the Mutation Testing on constraints, which evaluates the quality of the current test campaign and adds new tests if needed. Conversions between binary and decimal formats are inevitable and introduce computational errors which can impact the reliability of test results. We strengthen our solution through the development and use of reliable arithmetic (multi-precision decimal interval arithmetic and binary/decimal mixed-radix arithmetic)
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Ben, Chikha Haithem. „Etude et Amélioration de Turbo-Codage Distribué pour les Réseaux Coopératifs“. Thesis, Valenciennes, 2012. http://www.theses.fr/2012VALE0011/document.
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Dans les systèmes radio mobiles, la diversité représente une technique efficace pour lutter contre l’évanouissement dû aux multi-trajets. La pleine diversité spatiale est atteinte dans les systèmes multiple-input multiple-output (MIMO). Mais, souvent l’intégration d’antennes multiples au niveau de l’émetteur ou du récepteur est coûteuse. Comme alternative, dans les réseaux sans fil multi-hop, la diversité coopérative garantit des gains de diversité spatiale en exploitant les techniques MIMO traditionnelles sans avoir besoin d’antennes multiples. En outre, la diversité coopérative fournit au réseau : un débit important, une énergie réduite et une couverture d’accès améliorée.Dans ce contexte, l’objectif de cette thèse est de concevoir des schémas de codage pour le canal à relais afin de réaliser une meilleure performance en termes de gain de diversité et de gain de codage. D’abord, nous étudions un système de turbo-codage distribué à L-relais en mode soft-decode-and-forward. Ensuite, nous proposons un système de turbocodage coopératif distribué à L-relais en utilisant la concaténation en parallèle des codes convolutifs. Enfin, afin d’améliorer la fiabilité de détection au niveau du noeud relais, nous proposons la technique de sélection d’antenne/relayage-soft. Pour une modulation BPSK, nous dérivons des expressions de la borne supérieure de la probabilité d’erreurbinaire où les différents sous-canaux sont supposés à évanouissement de Rayleigh, indépendants et pleinement entrelacés avec une information instantanée d’état de canal idéal. Une validation des résultats théoriques est également menée par la simulationDiversity provides an efficient method for combating multipath fading in mobile radio systems. One of the most common forms of spatial diversity is multiple-input multipleoutput (MIMO), where full diversity is obtained. However, embedding multiple antennas at the transmitter or the receiver can sometimes be expensive. As an alternative to collocated antennas, cooperative diversity in wireless multi-hop networks confirms their ability to achieve spatial diversity gains by exploiting the spatial diversity of the traditional MIMO techniques, without each node necessarily having multiple antennas. In addition, cooperative diversity has been shown to provide the network with importantthroughput, reduced energy requirements and improved access coverage.In light of this, the objective of this thesis is to devise coding schemes suitable for relay channels that aim at showing the best compromise between performance of diversity and coding gains. Firstly, we investigate a distributed turbo coding scheme dedicated to L-relay channels operating in the soft-decode-and-forward mode. Then, we present a proposed distributed turbo coded cooperative (DTCC) scheme, called parallel concatenated convolutional-based distributed coded cooperation. Finally, we investigate antenna/soft-relaying selection for DTCC networks in order to improve their end-to-end performance. Assuming BPSK transmission for fully interleaved channels with ideal channel state information, we define the explicit upper bounds for error probability inRayleigh fading channels with independent fading. Both theoretical limits and simulation results are presented to demonstrate the performances
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Vergnat, Michel. „Hydrogénation d'alliages semi-conducteurs amorphes : Structure et propriétés électroniques des alliages amorphes hydrogènes SI::(1-X)SN::(X):H“. Nancy 1, 1988. http://www.theses.fr/1988NAN10322.
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Les atomes d'hydrogène sont introduits dans les couches durant leur élaboration par évaporation. L'influence des paramètres de préparation est mise en évidence sur les propriétés physiques de couches de SI pur. Les alliages SI::(1-X)SN::(X) et SI::(1-X)SN::(X) : H peuvent être préparés à l'état amorphe dans une large gamme de compositions. Des études de diffraction électronique, de spectrométrie moessbauer et des mesures de densité massique montrent que ces alliages possèdent une structure tétraédrique. Cette méthode a également permis d'élaborer des multicouches SI/SI : H, de l'étain semiconducteur et de l'hydrure de titane
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Rouxel, Yann. „Coévaporation avec masquage mécanique de ZnSe et de LaF3, pour la réalisation de couches minces à profils d'indice continus périodiques“. Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10096.
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Dans une etude theorique des structures a profil d'indice continu, il est montre que l'essentiel des proprietes spectrales des filtres a profil d'indice sinusoidal peut etre etudie de maniere analytique a partir de certaines proprietes de l'equation de mathieu. L'etude experimentale de ces structures a ete realisee a l'aide d'une technique de coevaporation par masquage mecanique. L'equipement de depot realisant la coevaporation a ete developpe pour permettre la realisation de couches sur substrat chaud pour des profils d'indice quelconques. Un systeme de mesure optique multispectral in-situ en reflectivite a egalement ete mis au point. Les proprietes des couches minces de melanges de znse et de laf3 ont ete etudiees pour toute la gamme de composition. Un schema d'evolution de la structure cristalline et de la porosite des couches en fonction de leur composition est propose. Les contraintes qui s'y developpent sont aussi analysees ainsi que leur evolution en fonction de l'environnement. L'etude des proprietes optiques a permis de definir les lois de melange ainsi que de mettre en evidence l'existence d'une birefringence evoluant avec la composition des melanges. Enfin, plusieurs types de structures periodiques ont ete realisees, comportant jusqu'a 20 periodes pour une epaisseur superieure a 5m. Les resultats ont permis de montrer que la modulation par masquage mecanique est une technique fiable et precise et que c'est le choix du couple de materiaux qui va conditionner la precision du controle du profil d'indice
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Okouyi, Antsina W'Ampoumou Rodrigue. „Faisabilité d'un système basé sur le DS-CDMA pour les futurs réseaux locaux sans fil à 60 GHz“. Lille 1, 2006. http://www.theses.fr/2005LIL12024.
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L'objectif de ce travail est d'étudier l'utilisation de la bande millimétrique autour de 60 GHz pour les futurs réseaux intra-bâtiment. Les contraintes imposées sont la simplicité des architectures, la souplesse d'utilisation et l'asynchronisme dès utilisateurs. Le choix, de la méthode d'accès multiples est la division par codes à séquence directe (DS-CDMA) sur des bandes de 250 MHz. Dans un premier temps, une étude théorique, qui repose sur un modèle statistique du canal développé à l'IEMN à partir de mesures, permet de déterminer la qualité de la transmission. Le réseau est centralisé et le récepteur mono-utilisateur. Notre étude unifie les calculs de taux d'erreur pour différentes techniques de diversité. Le contrôle de puissance est pris en compte et, s'il est parfait, les résultats montrent des capacités de l'ordre de 17 utilisateurs avec un débit de 8 Mbits/s par sous bande, pour un taux d'erreur binaire sans codage canal de 10-2 et une portée d'une dizaine de mètres. Nous proposons ensuite des méthodes de simulation du système. Elles nous permettent d'introduire différentes formes d'ondes, des défauts de synchronisation et ainsi d'en étudier les impacts. Enfin, la technique à étalement de spectre par combinaison parallèle a été adoptée pour gérer les débits variables. Cette technique permet à un utilisateur de changer son débit à la demande sans modifier la qualité des liens des autres utilisateurs. Par sa conception, elle assure de bonnes performances et nous l'avons modifiée afin d'obtenir une réduction de la complexité du système. A l'issue de cette étude, le DS-CDMA apparaît comme une technique de partage de la ressource du canal intéressante pour les futurs réseaux locaux sans fil dans la bande millimétrique des 60 GHz.
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Kaddoum, Georges. „Contributions à l’amélioration des systèmes de communication multi-utilisateur par chaos : synchronisation et analyse des performances“. Toulouse, INSA, 2008. http://eprint.insa-toulouse.fr/archive/00000245/.
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Les radiocommunications constituent actuellement un domaine en plein essor. Depuis quelques années, de nombreux chercheurs étudient la possibilité d'utiliser des signaux chaotiques pour transmettre des données, en particulier dans un contexte multi-utilisateurs. Parmi les différentes techniques d'accès multiple, le CDMA (Code Division Multiple Access) permet à différents utilisateurs de transmettre simultanément sur la même bande de fréquence. Les séquences utilisées actuellement pour l'étalement du spectre sont des séquences dites pseudo-aléatoires binaires à faible intercorrélation générées sur la base d'un registre à décalage (les séquences de Gold) ou bien des séquences binaires orthogonales (les séquences de Walsh). Cette thèse porte sur l’étude d’un système de communication multi-utilisateurs par étalement de spectre utilisant des générateurs de chaos. Les signaux chaotiques peuvent être générés par des systèmes itératifs discrets modélisés par des transformations ponctuelles. Dans un premier temps, nous avons étudié les signaux chaotiques issus de différents systèmes dynamiques, /a priori/ définis par des fonctions classiques continues ou continues par morceaux. En se basant sur les propriétés de corrélation et sur les distributions des énergies des signaux chaotiques, une étude comparative entre les différentes séquences chaotiques a été faite dans le cadre d’une transmission DS-CDMA par séquence chaotique. Le but de cette comparaison est de fournir des éléments permettant de choisir la séquence la mieux adaptée à l’étalement du spectre. Une méthode simple rapide et précise pour prédire le taux d’erreurs binaires pour des systèmes DS-CDMA basé sur le chaos a été proposée en mode mono et multi-utilisateur. Une étude plus poussée sur la distribution de l’énergie a permis d’établir une expression analytique du taux d’erreurs binaires. Ces calculs de performances ont été étendus à un canal de transmission à multi-trajets en mode multi-utilisateurs. Nous avons exploré ensuite le processus de synchronisation des systèmes dynamiques chaotiques. Tout d’abord, nous avons porté notre attention sur l’étude des différentes méthodes d’intégration numérique afin de déterminer une méthode adaptée permettant de réaliser la synchronisation chaotique par couplage avec une faible charge de calcul. Enfin, toujours dans l’idée d’établir la synchronisation du chaos pour les systèmes de transmission de type DS-CDMA. Nous avons proposé des récepteurs intégrant des unités de synchronisation similaires aux unités de synchronisations (/acquisition et poursuite/) utilisées dans les systèmes classiques à étalement du spectre. Ces unités de synchronisations utilisent simultanément une séquence binaire pseudo-aléatoire classique et une séquence chaotique pour établir et maintenir la synchronisation. Ces techniques ont été comparées à une méthode similaire de la littérature, ce qui a permis de montrer l’amélioration de la performance des systèmes proposés, et notamment le fait qu’ils soient opérationnels en mode asynchroneRadiocommunications field is currently in full development. In recent years, many researchers have explored the possibility of using chaotic signals to transmit data, especially in a multi-user case. Among the various multiple access techniques, the CDMA (Code Division Multiple Access) allows different users to transmit simultaneously on the same frequency band. The sequences currently used for classical spread spectrum are the sequences known as pseudo-random binary sequences with low cross-correlation generated on the basis of a shift linear register (Gold sequences) or binary orthogonal sequences (Walsh codes). This thesis has focused on the study of a communication system with multi-user spread spectrum using chaotic generators as spreading sequences. The chaotic signals can be generated by iterative discrete systems modelled by discrete transformations. In a first step, we have studied various chaotic signals from different dynamical systems, / a priori / defined by traditional functions continuous or piece wise linear functions. Relying on the correlation properties and the energy distribution of chaotic signals, a comparative study between different chaotic sequences was made in the framework of chaos-based DS-CDMA systems. The purpose of this comparison is to provide necessary elements to choose the best sequence for a spread spectrum system under an Additive White Gaussian Noise (AWGN) channel. A simple method to rapidly and accurately predict the bit error rate for chaos-based DS-CDMA was proposed in single and multi-user cases. Further study on the energy distribution has resulted in an analytical expression of the bit error rate. These performances have been also been studied and extended to the multi-user case. In a second part, we have explored the synchronization process of chaotic dynamical systems. After reviewing the existing approaches in the literature, we have focused our attention on the study of different methods of digital integration in order to determine an appropriate method to achieve synchronization using coupling with a low a low computing charge. Finally, we have studied the synchronization process for chaos-based DS-CDMA system. We have proposed receivers incorporating synchronization units similar to the synchronization units (/ acquisition and tracking /) used in conventional spread spectrum systems. These synchronization units are using simultaneously a classical binary pseudo-random sequence together with a chaotic sequence in order to achieve and maintain synchronization. These techniques were compared to a similar existing method recently proposed in literature. We have demonstrate the improvement in performance brought by our proposed system, including the fact that this system is also operational in the asynchronous case
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Hitchcock, Yvonne Roslyn. „Elliptic Curve Cryptography for Lightweight Applications“. Queensland University of Technology, 2003. http://eprints.qut.edu.au/15838/.
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Elliptic curves were first proposed as a basis for public key cryptography in the mid 1980's. They provide public key cryptosystems based on the difficulty of the elliptic curve discrete logarithm problem (ECDLP) , which is so called because of its similarity to the discrete logarithm problem (DLP) over the integers modulo a large prime. One benefit of elliptic curve cryptosystems (ECCs) is that they can use a much shorter key length than other public key cryptosystems to provide an equivalent level of security. For example, 160 bit ECCs are believed to provide about the same level of security as 1024 bit RSA. Also, the level of security provided by an ECC increases faster with key size than for integer based discrete logarithm (dl) or RSA cryptosystems. ECCs can also provide a faster implementation than RSA or dl systems, and use less bandwidth and power. These issues can be crucial in lightweight applications such as smart cards. In the last few years, ECCs have been included or proposed for inclusion in internationally recognized standards. Thus elliptic curve cryptography is set to become an integral part of lightweight applications in the immediate future. This thesis presents an analysis of several important issues for ECCs on lightweight devices. It begins with an introduction to elliptic curves and the algorithms required to implement an ECC. It then gives an analysis of the speed, code size and memory usage of various possible implementation options. Enough details are presented to enable an implementer to choose for implementation those algorithms which give the greatest speed whilst conforming to the code size and ram restrictions of a particular lightweight device. Recommendations are made for new functions to be included on coprocessors for lightweight devices to support ECC implementations Another issue of concern for implementers is the side-channel attacks that have recently been proposed. They obtain information about the cryptosystem by measuring side-channel information such as power consumption and processing time and the information is then used to break implementations that have not incorporated appropriate defences. A new method of defence to protect an implementation from the simple power analysis (spa) method of attack is presented in this thesis. It requires 44% fewer additions and 11% more doublings than the commonly recommended defence of performing a point addition in every loop of the binary scalar multiplication algorithm. The algorithm forms a contribution to the current range of possible spa defences which has a good speed but low memory usage. Another topic of paramount importance to ECCs for lightweight applications is whether the security of fixed curves is equivalent to that of random curves. Because of the inability of lightweight devices to generate secure random curves, fixed curves are used in such devices. These curves provide the additional advantage of requiring less bandwidth, code size and processing time. However, it is intuitively obvious that a large precomputation to aid in the breaking of the elliptic curve discrete logarithm problem (ECDLP) can be made for a fixed curve which would be unavailable for a random curve. Therefore, it would appear that fixed curves are less secure than random curves, but quantifying the loss of security is much more difficult. The thesis performs an examination of fixed curve security taking this observation into account, and includes a definition of equivalent security and an analysis of a variation of Pollard's rho method where computations from solutions of previous ECDLPs can be used to solve subsequent ECDLPs on the same curve. A lower bound on the expected time to solve such ECDLPs using this method is presented, as well as an approximation of the expected time remaining to solve an ECDLP when a given size of precomputation is available. It is concluded that adding a total of 11 bits to the size of a fixed curve provides an equivalent level of security compared to random curves. The final part of the thesis deals with proofs of security of key exchange protocols in the Canetti-Krawczyk proof model. This model has been used since it offers the advantage of a modular proof with reusable components. Firstly a password-based authentication mechanism and its security proof are discussed, followed by an analysis of the use of the authentication mechanism in key exchange protocols. The Canetti-Krawczyk model is then used to examine secure tripartite (three party) key exchange protocols. Tripartite key exchange protocols are particularly suited to ECCs because of the availability of bilinear mappings on elliptic curves, which allow more efficient tripartite key exchange protocols.
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Muralidhar, Shubha. „Systolic integer divider for Sunar-Koc ONB type II multiplier“. Thesis, 2017. http://hdl.handle.net/1828/7882.
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This thesis focuses on the Binary Integer Modulo-Division Algorithm that is essential for the
permutation process in Sunar-Koc ONB Type II Multiplier and also for other general purposes.
This thesis explains the new algorithm developed based on the systolic array architecture which gives a systematic approach to the iterative process for the Modulo-Division. The scheduling and projection timing functions are proposed for the processor array allocation and the matlab code has been implemented to verify the efficiency of the algorithm. The thesis also explores the possibility of word based algorithm for design optimisation.Graduate
0544
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m.shubha8@gmail.com
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Wu, Sheng-Lun, und 吳聖倫. „Time-Area Efficient Digital-Serial Montgomery Multiplier Using Karatsuba Algorithm and Redundant Binary Representation over 2n-1“. Thesis, 2019. http://ndltd.ncl.edu.tw/handle/d5qfe2.
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碩士國立交通大學
資訊學院資訊學程
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In this thesis, we will propose a time-area efficient digital-serial montgomery multiplier over 2^n-1 to improve the computing performance. According to the embedded system is growing, how to keep the security in limited resource and computing power will be an important topic. The combination of Karatsuba’s algorithm and redundant binary representation (RBR) eliminates the carry-chain issue. The digital-serial structure can simplify the complexity of reconstruction further. From the simulation results, in prime field multiplier, there are improvements with 69.9% for the Radix-8 Booth Encoded 64-bit [9]. We also have an improvement up to 46.9% compared with the binary field multiplier [11] can be attained.