To see the other types of publications on this topic, follow the link: Output error.
Dissertations / Theses on the topic 'Output error'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Output error.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Tohme, Elie. "Initialization of output error identification algorithms." Poitiers, 2008. http://www.theses.fr/2008POIT2259.
Full textAbstract:
Cette thèse traite de l'initialisation des algorithmes à erreur de sortie pour approcher la convergence globale. Deux approches sont proposées. La première s'appuie sur les moments partiels réinitialisés. Cette approche de type erreur d'équation est comparée à d'autres méthodes par simulation stochastique dans les cas discrets et continus. Les résultats obtenus montrent l'efficacité des moments partiels réinitialisés pour l'initialisation des algorithmes à erreur de sortie. Dans la deuxième approche, les algorithmes proposés, dits à pseudo-erreur de sortie, sont construits à partir des méthodes standards d'erreur de sortie en tentant de respecter une hypothèse de passivité qui assure la convergence globale. Malgré un biais sur les paramètres obtenus, ceux-ci fournissent une bonne initialisation des algorithmes à erreur de sortieThis thesis deals with the initialization of output error identification algorithms in order to achieve the global convergence. Two approaches are proposed. The first approach is based on the reinitialized partial moments. This equation error type approach is compared with several methods using stochastic simulations in both discrete and continuous domains. The obtained results show the efficiency of the reinitialized partial moments to initialize output error algorithms. In the second approach, the proposed algorithms, named pseudo-output error algorithms, are built from the standard output error methods by trying to satisfy a particular positive realness condition that assures the global convergence. Despite the bias of the estimated parameters, these approaches provide a good initialization to the output error algorithms
2
Tidefelt, Henrik. "Applied Output Error Identification: SI Engine Under Normal Operating Conditions." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2380.
Full textAbstract:
This report presents work done in the field of output error identification, with application to spark ignition (SI) engine identification for the purpose of air to fuel ratio control. The generic parts of the project consist mainly in setting out the basis for the design of output error identification software. Efficiency issues related to linear state space models have also been explored, and although the software design is not made explicit in this report, many of the important concepts have been implemented in order to provide powerful abstractions for the application to SI engine identification.
The SI engine identification data was obtained under normal operating conditions. The goal is to re- estimate models without utilizing a virtual measurement which has been used successfully to estimate models in the past. This turns out to be a difficult problem much related to the lack of excitation in the system input, shortcomings of the fuel dynamics model and the unknown and hard to estimate exhaust sensor characteristics. Indeed, the larger of the previously estimated models are found not to be identifiable in the present situation. However, trivial restrictions of the models (not meaning restriction to trivial models) avoid that problem.
3
Carew, Warren D. "Multivariable control of a nonlinear process : output prioritisation by error redistribution." Doctoral thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/5255.
Full text
4
Carlstedt, Tobias. "Algorithms for analysis of GSM phones’ modulation quality." Thesis, Linköping University, Department of Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17248.
Full text
5
Zorian, Yervant. "Optimized error coverage in built-in self-test by output data modification." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75778.
Full textAbstract:
The concept of Built-In Self-Test (BIST) has recently become an increasingly attractive solution to the complex problem of testing VLSI chips. However, the realization of BIST faces some challenging problems of its own. One of these problems is to increase the quality of fault coverage of a BIST implementation, without incurring a large overhead. In particular, the loss of information in the output data compressor, which is typically a multi-input linear feedback shift register (MISR), is a major cause of concern.In the recent past, several researchers have proposed different schemes to reduce this loss of information, while maintaining the need for a small area overhead.
In this dissertation, a new BIST scheme, based on modifying the output data before compression, is developed. This scheme, called output data modification (ODM), exploits the knowledge of the functionality of the circuit under test to provide a circuit-specific BIST structure. This structure is developed so that it can conveniently be implemented for any general circuit under consideration. But more importantly, a proof of effectiveness is provided to show that ODM will, on the average, be orders of magnitude better than all existing schemes in its capability to reduce the information loss, for a given amount of area overhead.
Moreover, the constructive nature of the proof will allow one to provide a simple trade-off between the reduction tolerated in information loss to the area overhead needed to affect this reduction.
6
Elliott, Debra. "Corpus-based machine translation evaluation via automated error detection in output texts." Thesis, University of Leeds, 2006. http://etheses.whiterose.ac.uk/221/.
Full textAbstract:
Since the emergence of the first fully automatic machine translation (MT) systems over fifty years ago, the use of MT has increased dramatically. Consequently, the evaluation of MT systems is crucial for all stakeholders. However, the human evaluation of MT output is expensive and time-consuming, often relying on subjective quality judgements and requiring human `reference translations' against which the output is compared. As a result, interest in more recent years has turned towards automated evaluation methods, which aim to produce scores that reflect human quality judgements. As the majority of published automated evaluation methods still require human `reference translations' for comparison, the goal of this research is to investigate the potential of a method that requires access only to the translation. Based on detailed corpus analyses, the primary aim is to devise methods for the automated detection of particular error types in French-English MT output from competing systems and to explore correlations between automated error counts and human judgements of a translation as a whole. First, a French-English corpus designed specifically for MT evaluation was compiled. A sample of MT output from the corpus was then evaluated by humans to provide judgements against which automated scores would ultimately be compared. A datadriven fluency error classification scheme was subsequently developed to enable the consistent manual annotation of errors found in the English MT output, without access to the original French text. These annotations were then used to guide the selection of error categories for automated error detection, and to facilitate the analysis of particular error types in context so that appropriate methods could be devised. Manual annotations were further used to evaluate the accuracy of each automated approach. Finally, error detection algorithms were tested on English MT output from German, Italian and Spanish to determine the extent to which methods would need to be adapted for use with other language pairs.
7
Cuéllar, Fuentes Jesús Seaman John W. Tubbs Jack Dale. "Statistical monitoring of a process with autocorrlated output and observable autocorrelated measurement error." Waco, Tex. : Baylor University, 2008. http://hdl.handle.net/2104/5185.
Full text
8
Luo, Yurong. "The severity of stages estimation during hemorrhage using error correcting output codes method." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/406.
Full textAbstract:
As a beneficial component with critical impact, computer-aided decision making systems have infiltrated many fields, such as economics, medicine, architecture and agriculture. The latent capabilities for facilitating human work propel high-speed development of such systems. Effective decisions provided by such systems greatly reduce the expense of labor, energy, budget, etc. The computer-aided decision making system for traumatic injuries is one type of such systems that supplies suggestive opinions when dealing with the injuries resulted from accidents, battle, or illness. The functions may involve judging the type of illness, allocating the wounded according to battle injuries, deciding the severity of symptoms for illness or injuries, managing the resources in the context of traumatic events, etc. The proposed computer-aided decision making system aims at estimating the severity of blood volume loss. Specifically speaking, accompanying many traumatic injuries, severe hemorrhage, a potentially life-threatening condition that requires immediate treatment, is a significant loss of blood volume in process resulting in decreased blood and oxygen perfusion of vital organs. Hemorrhage and blood loss can occur in different levels such as mild, moderate, or severe. Our proposed system will assist physicians by estimating information such as the severity of blood volume loss and hemorrhage , so that timely measures can be taken to not only save lives but also reduce the long-term complications as well as the cost caused by unmatched operations and treatments. The general framework of the proposed research contains three tasks and many novel and transformative concepts are integrated into the system. First is the preprocessing of the raw signals. In this stage, adaptive filtering is adopted and customized to filter noise, and two detection algorithms (QRS complex detection and Systolic/Diastolic wave detection) are designed. The second process is to extract features. The proposed system combines features from time domain, frequency domain, nonlinear analysis, and multi-model analysis to better represent the patterns when hemorrhage happens. Third, a machine learning algorithm is designed for classification of patterns. A novel machine learning algorithm, as a new version of error correcting output code (ECOC), is designed and investigated for high accuracy and real-time decision making. The features and characteristics of this machine learning method are essential for the proposed computer-aided trauma decision making system. The proposed system is tested agasint Lower Body Negative Pressure (LBNP) dataset, and the results indicate the accuracy and reliability of the proposed system.
9
Park, Jong Il. "Trellis based soft output decoding algorithms for concatenated coding systems." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13898.
Full text
10
Potter, Chris. "Modeling Channel Estimation Error in Continuously Varying MIMO Channels." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604490.
Full textAbstract:
ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaThe accuracy of channel estimation plays a crucial role in the demodulation of data symbols sent across an unknown wireless medium. In this work a new analytical expression for the channel estimation error of a multiple input multiple output (MIMO) system is obtained when the wireless medium is continuously changing in the temporal domain. Numerical examples are provided to illustrate our findings.
11
Ding, Minhua. "Multiple-input multiple-output wireless system designs with imperfect channel knowledge." Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1335.
Full text
12
Sun, Huafei. "Impact of triangle shapes using high-order discretizations and direct mesh adaptation for output error." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54215.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 95-101).
The impact of triangle shapes, including angle sizes and aspect ratios, on accuracy and stiffness is investigated for simulations of highly anisotropic problems. The results indicate that for high-order discretizations, large angles do not have an adverse impact on solution accuracy. However, a correct aspect ratio is critical for accuracy for both linear and high-order discretizations. In addition, large angles are not problematic for the conditioning of the linear systems arising from discretization. They can be overcome through small increases in preconditioning costs. A direct adaptation scheme that controls the output error via mesh operations and mesh smoothing is also developed. The decision of mesh operations is solely based on output error distribution without any a priori assumption on error convergence rate. Anisotropy is introduced by evaluating the error changes due to potential edge split, and thus the anisotropies of both primal and dual solutions are taken into account. This scheme is demonstrated to produce grids with fewer degrees of freedom for a specified error level than the existing metric-based approach.
by Huafei Sun.
S.M.
13
Kestell, Colin D. "Active control of sound in a small single engine aircraft cabin with virtual error sensors." Title page, abstract and contents only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phk423.pdf.
Full text
14
Zhang, Yi. "Learning with Limited Supervision by Input and Output Coding." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/156.
Full textAbstract:
In many real-world applications of supervised learning, only a limited number of labeled examples are available because the cost of obtaining high-quality examples is high. Even with a relatively large number of labeled examples, the learning problem may still suffer from limited supervision as the complexity of the prediction function increases. Therefore, learning with limited supervision presents a major challenge to machine learning. With the goal of supervision reduction, this thesis studies the representation, discovery and incorporation of extra input and output information in learning.
Information about the input space can be encoded by regularization. We first design a semi-supervised learning method for text classification that encodes the correlation of words inferred from seemingly irrelevant unlabeled text. We then propose a multi-task learning framework with a matrix-normal penalty, which compactly encodes the covariance structure of the joint input space of multiple tasks. To capture structure information that is more general than covariance and correlation, we study a class of regularization penalties on model compressibility. Then we design the projection penalty, which encodes the structure information from a dimension reduction while controlling the risk of information loss.
Information about the output space can be exploited by error correcting output codes. Using the composite likelihood view, we propose an improved pairwise coding for multi-label classification, which encodes pairwise label density (as opposed to label comparisons) and decodes using variational methods. We then investigate problemdependent codes, where the encoding is learned from data instead of being predefined. We first propose a multi-label output code using canonical correlation analysis, where predictability of the code is optimized. We then argue that both discriminability and predictability are critical for output coding, and propose a max-margin formulation that promotes both discriminative and predictable codes.
We empirically study our methods in a wide spectrum of applications, including document categorization, landmine detection, face recognition, brain signal classification, handwritten digit recognition, house price forecasting, music emotion prediction, medical decision, email analysis, gene function classification, outdoor scene recognition, and so forth. In all these applications, our proposed methods for encoding input and output information lead to significantly improved prediction performance.
15
Thompson, Grant. "Effects of DEM resolution on GIS-based solar radiation model output: A comparison with the National Solar Radiation Database." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258663688.
Full text
16
Potter, Chris, Kurt Kosbar, and Adam Panagos. "Effects of Synchronization Error on Space Time Block Codes Equipped with FSK Waveforms." International Foundation for Telemetering, 2009. http://hdl.handle.net/10150/605966.
Full textAbstract:
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, NevadaSpace-time Coding (STC) for Multiple-Input Multiple-Output (MIMO) wireless communication systems is an effective technique for providing robust wireless link performance in telemetry systems. This paper investigates the degradation in system performance when synchronization errors between the transmitter and receiver are present. Specifically, expressions that quantify the increase in symbol-error-rate as a function of symbol synchronization error are derived for a two-transmit and single receive antenna MISO system using binary frequency shift keying waveforms. These results are then extended to the MIMO case. The analytic results are verified with simulation results that show close agreement between the theoretical expressions and Monte Carlo simulation runs.
17
Carson, Hugh Alexander. "A priori analysis of global and local output error estimates for CG, DG and HDG finite element discretizations." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105608.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 103-105).
In this thesis, a priori convergence estimates are developed for outputs, output error estimates, and localizations of output error estimates for Galerkin finite element methods. Specifically, Continuous Galerkin (CG), Discontinuous Galerkin (DG), and Hybridized DG (HDG) methods are analyzed for the Poisson problem. A mixed formulation for DG output error estimation is proposed with improved convergence rates relative to the common approach utilizing statically condensed, p-dependent lifting operators. The HDG output error estimates are new and include the impact of stabilization. Comparisons to numerical results demonstrate (1) the sharpness of the estimates and (2) that the HDG estimates are approximately an order of magnitude more accurate than CG and DG.
by Hugh Alexander Carson.
S.M.
18
Kulkarni, Aditya. "Performance Analysis of Zero Forcing and Minimum Mean Square Error Equalizers on Multiple Input Multiple Output System on a Spinning Vehicle." International Foundation for Telemetering, 2014. http://hdl.handle.net/10150/577482.
Full textAbstract:
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CAChannel equalizers based on minimum mean square error (MMSE) and zero forcing (ZF) criteria have been formulated for a general scalable multiple input multiple output (MIMO) system and implemented for a 2x2 MIMO system with spatial multiplexing (SM) for Rayleigh channel associated with additive white Gaussian noise. A model to emulate transmitters and receivers on a spinning vehicle has been developed. A transceiver based on the BLAST architecture is developed in this work. A mathematical framework to explain the behavior of the ZF and MMSE equalizers is formulated. The performance of the equalizers has been validated for a case with one of the communication entities being a spinning aero vehicle. Performance analysis with respect to variation of angular separation between the antennas and relative antenna gain for each case is presented. Based on the simulation results a setup with optimal design parameters for placement of antennas, choice of the equalizers and transmit power is proposed.
19
Zikmund, Pavel. "Identifikace aerodynamických charakteristik atmosférického letadla z výsledků letových měření." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-234162.
Full textAbstract:
The thesis deals with aerodynamic characteristics identification from flight measurement. The topic is part of flight mechanic – handling qualities. The first theoretic part consists of three identification methods description: Error equation method, Output error method and Filter error method. Mathematical model of an airplane is defined and restricted to the motion with 3 degree of freedom. There is also introduced simulation of flight measurement for identification software validation. Practical part is focused on experiment preparation, execution and evaluation. The airplane VUT 700 Specto had been chosen to carry out flight tests. The airplane was modified to the new electric powered VUT 700e Specto after first measurement flights with combustion engine. Data record from on-board measurement unit was completed by telemetric data from autopilot and remote control system. Flight tests were carried out in stabilised mode of autopilot in symmetric flight. The results were confronted with analytical analysis results and DATCOM+ software parameter estimation.
20
Dang, Xiaoyu. "An Optimum Detector for Space-Time Trellis Coded Differential MSK." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604515.
Full textAbstract:
ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaThe accuracy of channel estimation plays a crucial role in the demodulation of data symbols sent across an unknown wireless medium. In this work a new analytical expression for the channel estimation error of a multiple input multiple output (MIMO) system is obtained when the wireless medium is continuously changing in the temporal domain. Numerical examples are provided to illustrate our findings. Space-time (ST) coding using Continuous Phase Modulation (CPM) has spectral advantages relative to linear modulations. In spite of the spectral benefits, Space-Time Trellis Codes (STTC) using the CPM implementation of Minimum Shift Keying (MSK) scheme has inherent inphase and quadrature interference, when the received complex baseband signal is the input into the matchfilter to remove the shaped sinusoid pulses. In this paper a novel optimum transmitting and detecting structure for STTC-MSK is proposed. Treating the Alamouti scheme as an outer code, each STTC MSK waveform frame is immediately followed by the orthogonal conjugate waveform frame at the transmit side. At the receiver first orthogonal wave forming is applied, then a new time-variant yet simple trellis structure of the STTC-MSK signals is developed. This STTC-MSK detector is absolutely guaranteed to be I/Q interference-free and still keeps a smaller computation load compared with STTC-QPSK. Simulations are made over quasi-static AWGN fading channel. It is shown that our detector for ST-MSK has solved the I/Q interference problem and has around 2.8 dB gain compared with the Alamouti Scheme and 3.8 dB gain for bit error rate at 5 X 10^(-3) in a 2 by 1 Multiple Input Single Output system.
21
Han, Gang. "Modeling the output from computer experiments having quantitative and qualitative input variables and its applications." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1228326460.
Full text
22
Escalera, Guerrero Sergio. "Coding and Decoding Design of ECOCs for Multi-class Pattern and Object Recognition." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/5789.
Full textAbstract:
Molts problemes de la vida quotidiana estan plens de decisions multi-classe. En l'àmbit del Reconeixement de Patrons, s'han proposat moltes tècniques d'aprenentatge que treballen sobre problemes de dos classes. No obstant, la extensió de classificadors binaris al cas multi-classe és una tasca complexa. En aquest sentit, Error-Correcting Output Codes (ECOC) han demostrat ser una eina potent per combinar qualsevol nombre de classificadors binaris i així modelar problemes multi-classe. No obstant, encara hi ha molts punts oberts sobre les capacitats del framework d'ECOC. En aquesta tesis, els dos estats principals d'un disseny ECOC són analitzats: la codificació i la decodificació. Es presenten diferents alternatives de dissenys dependents del domini del problema. Aquests dissenys fan ús del coneixement del domini del problema per minimitzar el nombre de classificadors que permeten obtenir un alt rendiment de classificació. Per altra banda, l'anàlisi de la codificació de dissenys d'ECOC es emprada per definir noves regles de decodificació que prenen total avantatja de la informació provinent del pas de la codificació. A més a més, com que classificacions exitoses requereixen rics conjunts de característiques, noves tècniques de detecció/extracció de característiques es presenten i s'avaluen en els nous dissenys d'ECOC. L'avaluació de la nova metodologia es fa sobre diferents bases de dades reals i sintètiques: UCI Machine Learning Repositori, símbols manuscrits, senyals de trànsit provinents de sistemes Mobile Mapping, imatges coronàries d'ultrasò, imatges de la Caltech Repositori i bases de dades de malats de Chagas. Els resultats que es mostren en aquesta tesis mostren que s'obtenen millores de rendiment rellevants tant a la codificació com a la decodificació dels dissenys d'ECOC quan les noves regles són aplicades.Many real problems require multi-class decisions. In the Pattern Recognition field, many techniques have been proposed to deal with the binary problem. However, the extension of many 2-class classifiers to the multi-class case is a hard task. In this sense, Error-Correcting Output Codes (ECOC) demonstrated to be a powerful tool to combine any number of binary classifiers to model multi-class problems. But there are still many open issues about the capabilities of the ECOC framework. In this thesis, the two main stages of an ECOC design are analyzed: the coding and the decoding steps. We present different problem-dependent designs. These designs take advantage of the knowledge of the problem domain to minimize the number of classifiers, obtaining a high classification performance. On the other hand, we analyze the ECOC codification in order to define new decoding rules that take full benefit from the information provided at the coding step. Moreover, as a successful classification requires a rich feature set, new feature detection/extraction techniques are presented and evaluated on the new ECOC designs. The evaluation of the new methodology is performed on different real and synthetic data sets: UCI Machine Learning Repository, handwriting symbols, traffic signs from a Mobile Mapping System, Intravascular Ultrasound images, Caltech Repository data set or Chaga's disease data set. The results of this thesis show that significant performance improvements are obtained on both traditional coding and decoding ECOC designs when the new coding and decoding rules are taken into account.
23
Simmons, Benjamin Mason. "System Identification of a Nonlinear Flight Dynamics Model for a Small, Fixed-Wing UAV." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/95324.
Full textAbstract:
This thesis describes the development of a nonlinear flight dynamics model for a small, fixed-wing unmanned aerial vehicle (UAV). Models developed for UAVs can be used for many applications including risk analysis, controls system design and flight simulators. Several challenges exist for system identification of small, low-cost aircraft including an increased sensitivity to atmospheric disturbances and decreased data quality from a cost-appropriate instrumentation system. These challenges result in difficulties in development of the model structure and parameter estimation. The small size may also limit the scope of flight test experiments and the consequent information content of the data from which the model is developed. Methods are presented to improve the accuracy of system identification which include data selection, data conditioning, incorporation of information from computational aerodynamics and synthesis of information from different flight test maneuvers. The final parameter estimation and uncertainty analysis was developed from the time domain formulation of the output-error method using the fully nonlinear aircraft equations of motion and a nonlinear aerodynamic model structure. The methods discussed increased the accuracy of parameter estimates and lowered the uncertainty in estimates compared to standard procedures for parameter estimation from flight test data. The significant contributions of this thesis are a detailed explanation of the entire system identification process tailored to the needs of a small UAV and incorporation of unique procedures to enhance identification results. This work may be used as a guide and list of recommendations for future system identification efforts of small, low-cost, minimally instrumented, fixed-wing UAVs.MS
24
Brunot, Mathieu. "Identification of rigid industrial robots - A system identification perspective." Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/20776/1/BRUNOT_Mathieu_20776.pdf.
Full textAbstract:
In modern manufacturing, industrial robots are essential components that allow saving cost, increase quality and productivity for instance. To achieve such goals, high accuracy and speed are simultaneously required. The design of control laws compliant with such requirements demands high-fidelity mathematical models of those robots. For this purpose, dynamic models are built from experimental data. The main objective of this thesis is thus to provide robotic engineers with automatic tools for identifying dynamic models of industrial robot arms. To achieve this aim, a comparative analysis of the existing methods dealing with robot identification is made. That allows discerning the advantages and the limitations of each method. From those observations, contributions are presented on three axes. First, the study focuses on the estimation of the joint velocities and accelerations from the measured position, which is required for the model construction. The usual method is based on a home-made prefiltering process that needs a reliable knowledge of the system’s bandwidths, whereas the system is still unknown. To overcome this dilemma, we propose a method able to estimate the joint derivatives automatically, without any setting from the user. The second axis is dedicated to the identification of the controller. For the vast majority of the method its knowledge is indeed required. Unfortunately, for copyright reasons, that is not always available to the user. To deal with this issue, two methods are suggested. Their basic philosophy is to identify the control law in a first step before identifying the dynamic model of the robot in a second one. The first method consists in identifying the control law in a parametric way, whereas the second one relies on a non-parametric identification. Finally, the third axis deals with the home-made setting of the decimate filter. The identification of the noise filter is introduced similarly to methods developed in the system identification community. This allows estimating automatically the dynamic parameters with low covariance and it brings some information about the noise circulation through the closed-loop system. All the proposed methodologies are validated on an industrial robot with 6 degrees of freedom. Perspectives are outlined for future developments on robotic systems identification and other complex problems.
25
Mirzaee, Alireza. "Turbo Receiver for Spread Spectrum Systems Employing Parity Bit Selected Spreading Sequences." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20635.
Full textAbstract:
In spread spectrum systems employing parity bit selected spreading sequences, parity
bits generated from a linear block encoder are used to select a spreading code from
a set of mutually orthogonal spreading sequences. In this thesis, turbo receivers for
SS-PB systems are proposed and investigated. In the transmitter, data bits are rst
convolutionally encoded before being fed into SS-PB modulator. In fact, the parity
bit spreading code selection technique acts as an inner encoder in this system without
allocating any transmit energy to the additional redundancy provided by this technique.
The receiver implements a turbo processing by iteratively exchanging the soft information
on coded bits between a SISO detector and a SISO decoder. In this system,
detection is performed by incorporating the extrinsic information provided by the decoder
in the last iteration into the received signal to calculate the likelihood of each
detected bit in terms of LLR which is used as the input for a SISO decoder.
In addition, SISO detectors are proposed for MC-CDMA and MIMO-CDMA systems
that employ parity bit selected and permutation spreading. In the case of multiuser
scenario, a turbo SISO multiuser detector is introduced for SS-PB systems for both
synchronous and asynchronous channels. In such systems, MAI is estimated from the
extrinsic information provided by the SISO channel decoder in the previous iteration.
SISO multiuser detectors are also proposed for the case of multiple users in MC-CDMA
and MIMO-CDMA systems when parity bit selected and permutation spreading are used.
Simulations performed for all the proposed turbo receivers show a signi cant reduction
in BER in AWGN and fading channels over multiple iterations.
26
Haider, Iqbal Hasan, and MD Fazla Rabby. "Performance Analysis of Cognitive Radio Network over SIMO System." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3439.
Full textAbstract:
As resources are limited, radio spectrum becomes congested due to the growth of wireless applications. However, measurements address the fact that most of the licensed spectrums experience low utilization even in intensively teeming areas. In the exertion to improve the utilization of the limited spectrum resources, cognitive radio networks have emerged as a powerful technique to resolve this problem. There are two types of user in cognitive radio networks (CRNs) named as primary user (PU) and secondary user (SU). Therein, the CRN enables the SU to utilize the unused licensed frequency of the PU if it possibly finds the vacant spectrum or white space (known as opportunistic spectrum access). Alternatively, SU can transmit simultaneously with the PU provided that transmission power of SU does not cause any harmful interference to the PU (known as spectrum sharing systems). In this thesis work, we study fundamental knowledge of the CRNs and focus on the performance analysis of the single input multiple output (SIMO) system for spectrum sharing approach. We assume that a secondary transmitter (SU-Tx) has full channel state information (CSI). The SU-Tx can adjust its transmit power not to cause harmful interference to the PU and obtain an optimal transmit rate. In particular, we derive the closed-form expressions for the cumulative distribution function (CDF), outage probability and an analytical expression for symbol error probability (SEP).As resources are limited, radio spectrum becomes congested due to the growth of wireless applications. However, measurements address the fact that most of the licensed spectrums experience low utilization even in intensively teeming areas. In the exertion to improve the utilization of the limited spectrum resources, cognitive radio networks have emerged as a powerful technique to resolve this problem. There are two types of user in cognitive radio networks (CRNs) named as primary user (PU) and secondary user (SU). Therein, the CRN enables the SU to utilize the unused licensed frequency of the PU if it possibly finds the vacant spectrum or white space (known as opportunistic spectrum access). Alternatively, SU can transmit simultaneously with the PU provided that transmission power of SU does not cause any harmful interference to the PU (known as spectrum sharing systems). In this thesis work, we study fundamental knowledge of the CRNs and focus on the performance analysis of the single input multiple output (SIMO) system for spectrum sharing approach. We assume that a secondary transmitter (SU-Tx) has full channel state information (CSI). The SU-Tx can adjust its transmit power not to cause harmful interference to the PU and obtain an optimal transmit rate. In particular, we derive the closed-form expressions for the cumulative distribution function (CDF), outage probability and an analytical expression for symbol error probability (SEP).
Iqbal Hasan Haider, cell: +46704571807 MD. Fazla Rabby, cell: +46734965477
27
Dang, Xiaoyu. "Space-Time Shaped Offset QPSK." International Foundation for Telemetering, 2008. http://hdl.handle.net/10150/606190.
Full textAbstract:
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, CaliforniaThis paper describes the use of orthogonal space-time block codes to overcome the performance and complexity difficulties associated with the use of Shaped Offset QPSK (SOQPSK) modulation, a ternary continuous phase modulation (CPM), in multiple-input multiple-output telemetry systems. The orthogonal space-time block code is applied to SOQPSK waveforms in the same way it would be applied to symbols. The procedure allows the receiver to orthogonalize the link. The main benefits of this orthogonalization are the easy realization of the transmit diversity for the offset-featured SQOSPK, and the removal of the noise correlation at the input to the space-time decoder and the elimination of I/Q interference when space time orthogonalization is applied to the symbol level.
28
Marcassoli, Giulia. "Gli output dei sistemi di traduzione automatica neurale: valutazione della qualità di Google Translate e DeepL Translator nella combinazione tedesco-italiano." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19536/.
Full textAbstract:
MT is becoming a powerful tool for professional translators, language service providers and common users. The present work focuses on its quality, evaluating the translations produced by two neural MT systems – i.e. Google Translate and DeepL Translator – through manual error annotation. The data set used for this task is composed of semi-specialized German texts translated into Italian. Aim of the present work is to assess the quality of MT outputs for the data set considered and obtain a detailed overview of the type of errors made by the two neural MT systems examined. The first part of this work provides a theoretical background for MT and its evaluation. Chapter 1 deals with the definition of MT and summarizes its history. Moreover, a detailed analysis of the different MT architectures is provided, as well as an overview of the possible application scenarios and the different categories of users. Chapter 2 introduces the notion of quality in the translation field and the main automatic and manual methods applied to MT quality assessment tasks. A comprehensive analysis of some of the most significant studies on neural and phrase-based MT systems output quality is then provided. The second part of this work presents a quality assessment of the output produced by two neural MT systems, i.e. Google Translation and DeepL Translator. The evaluation was performed through manual error annotation based on a fine-grained error taxonomy. Chapter 3 outlines the methodology followed during the evaluation, with a description of the dataset, the neural MT systems chosen for the study, the annotation tool and the taxonomy used during the annotation task. Chapter 4 provides the results of the evaluation and a comment thereof, offering examples extracted from the annotated data set. The final part of this work summarizes the major findings of the present contribution. Results are then discussed, with a focus on their implication for future work.
29
Arustei, Adrian. "Development of a System Identification Tool for Subscale Flight Testing." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157292.
Full textAbstract:
Aircraft system identification has been widely used to this day in applications like control law design, building simulators or extending flight envelopes. It can also be utilized for determining flight-mechanical characteristics in the preliminary design phase of a flight vehicle. In this thesis, three common time-domain methods were implemented in MATLAB for determining the aerodynamic derivatives of a subscale aircraft. For parameter estimation, the equation-error method is quick, robust and can provide good parameter estimates on its own. The output-error method is computationally intensive but keeps account of the aircraft's evolution in time, being more suitable for fine-tuning predictive models. A new model structure is identified using multivariate orthogonal functions with a predicted squared error stopping criteria. This method is based on linear regression (equation-error). The code written is flexible and can also be used for other aircraft and with other aerodynamic models. Simulations are compared with experimental data from a previous flight test campaign for validation. In the future, this tool may help taking decisions in conceptual design after a prototype is tested.
30
Chester, Ryan T. "Error Sensor Strategies for Active Noise Control and Active Acoustic Equalization in a Free Field." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2298.pdf.
Full text
31
Chaudhari, Pragat. "Analytical Methods for the Performance Evaluation of Binary Linear Block Codes." Thesis, University of Waterloo, 2000. http://hdl.handle.net/10012/904.
Full textAbstract:
The modeling of the soft-output decoding of a binary linear block code using a Binary Phase Shift Keying (BPSK) modulation system (with reduced noise power) is the main focus of this work. With this model, it is possible to provide bit error performance approximations to help in the evaluation of the performance of binary linear block codes. As well, the model can be used in the design of communications systems which require knowledge of the characteristics of the channel, such as combined source-channel coding. Assuming an Additive White Gaussian Noise channel model, soft-output Log Likelihood Ratio (LLR) values are modeled to be Gaussian distributed. The bit error performance for a binary linear code over an AWGN channel can then be approximated using the Q-function that is used for BPSK systems. Simulation results are presented which show that the actual bit error performance of the code is very well approximated by the LLR approximation, especially for low signal-to-noise ratios (SNR). A new measure of the coding gain achievable through the use of a code is introduced by comparing the LLR variance to that of an equivalently scaled BPSK system. Furthermore, arguments are presented which show that the approximation requires fewer samples than conventional simulation methods to obtain the same confidence in the bit error probability value. This translates into fewer computations and therefore, less time is needed to obtain performance results. Other work was completed that uses a discrete Fourier Transform technique to calculate the weight distribution of a linear code. The weight distribution of a code is defined by the number of codewords which have a certain number of ones in the codewords. For codeword lengths of small to moderate size, this method is faster and provides an easily implementable and methodical approach over other methods. This technique has the added advantage over other techniques of being able to methodically calculate the number of codewords of a particular Hamming weight instead of calculating the entire weight distribution of the code.
32
Ganji, Saichand. "Space-Time Block Coding to Achieve Spatial Diversity in a Multiple Input Multiple Output System." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1534432423784957.
Full text
33
Fu, Wenjun. "From the conventional MIMO to massive MIMO systems : performance analysis and energy efficiency optimization." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/25672.
Full textAbstract:
The main topic of this thesis is based on multiple-input multiple-output (MIMO) wireless communications, which is a novel technology that has attracted great interest in the last twenty years. Conventional MIMO systems using up to eight antennas play a vital role in the urban cellular network, where the deployment of multiple antennas have significantly enhanced the throughput without taking extra spectrum or power resources. The massive MIMO systems “scales” up the benefits that offered by the conventional MIMO systems. Using sixty four or more antennas at the BS not only improves the spectrum efficiency significantly, but also provides additional link robustness. It is considered as a key technology in the fifth generation of mobile communication technology standards network, and the design of new algorithms for these two systems is the basis of the research in this thesis. Firstly, at the receiver side of the conventional MIMO systems, a general framework of bit error rate (BER) approximation for the detection algorithms is proposed, which aims to support an adaptive modulation scheme. The main idea is to utilize a simplified BER approximation scheme, which is based on the union bound of the maximum-likelihood detector (MLD), whereby the bit error rate (BER) performance of the detector for the varying channel qualities can be efficiently predicted. The K-best detector is utilized in the thesis because its quasi- MLD performance and the parallel computational structure. The simulation results have clearly shown the adaptive K-best algorithm, by applying the simplified approximation method, has much reduced computational complexity while still maintaining a promising BER performance. Secondly, in terms of the uplink channel estimation for the massive MIMO systems with the time-division-duplex operation, the performance of the Grassmannian line packing (GLP) based uplink pilot codebook design is investigated. It aims to eliminate the pilot contamination effect in order to increase the downlink achievable rate. In the case of a limited channel coherence interval, the uplink codebook design can be treated as a line packing problem in a Grassmannian manifold. The closed-form analytical expressions of downlink achievable rate for both the single-cell and multi-cell systems are proposed, which are intended for performance analysis and optimization. The numerical results validate the proposed analytical expressions and the rate gains by using the GLP-based uplink codebook design. Finally, the study is extended to the energy efficiency (EE) of the massive MIMO system, as the reduction carbon emissions from the information and communication technology is a long-term target for the researchers. An effective framework of maximizing the EE for the massive MIMO systems is proposed in this thesis. The optimization starts from the maximization of the minimum user rate, which is aiming to increase the quality-of-service and provide a feasible constraint for the EE maximization problem. Secondly, the EE problem is a non-concave problem and can not be solved directly, so the combination of fractional programming and the successive concave approximation based algorithm are proposed to find a good suboptimal solution. It has been shown that the proposed optimization algorithm provides a significant EE improvement compared to a baseline case.
34
Dittrich, Petr. "Odhad Letových Parametrů Malého Letounu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2017. http://www.nusl.cz/ntk/nusl-412582.
Full textAbstract:
Tato práce je zaměřena na odhad letových parametrů malého letounu, konkrétně letounu Evektor SportStar RTC. Pro odhad letových parametrů jsou použity metody "Equation Error Method", "Output Error Method" a metody rekurzivních nejmenších čtverců. Práce je zaměřena na zkoumání charakteristik aerodynamických parametrů podélného pohybu a ověření, zda takto odhadnuté letové parametry odpovídají naměřeným datům a tudíž vytvářejí předpoklad pro realizaci dostatečně přesného modelu letadla. Odhadnuté letové parametry jsou dále porovnávány s a-priorními hodnotami získanými s využitím programů Tornado, AVL a softwarovéverze sbírky Datcom. Rozdíly mezi a-priorními hodnotami a odhadnutými letovými paramatery jsou porovnány s korekcemi publikovanými pro subsonické letové podmínky modelu letounu F-18 Hornet.
35
Islam, Muhammad Adeel, and Khan Ahmad Shah. "Performance analysis of dual hop cellular networks." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3093.
Full textAbstract:
Explosive growth in wireless technology caused by development in digital and RF circuit fabrications put some serious challenges on wireless system designers and link budget planning. Low transmit power, system coverage and capacity, high data rates, spatial diversity and quality of services (QOS) are the key factors in future wireless communication system that made it attractive. Dual-hop relaying is the promising underlying technique for future wireless communication to address such dilemmas. Based on dual-hop relaying this thesis addresses two scenarios. In the first case the system model employs dual-hop amplify and forward (AF) multiple input multiple output (MIMO) relay channels with transmit and receive antenna selection over independent Rayleigh fading channels where source and destination contain multiple antennas and communicate with each other with help of single antenna relay. It is assumed that the source and destination has perfect knowledge of channel state information (CSI). Our analysis shows that full spatial diversity order can be achieved with minimum number of antennas at source and destination i.e. min{N_s N_d }. In the second case the performance analysis of dual-hop amplify and forward (AF) multiple relay cooperative diversity network with best relay selection schemes over Rayleigh fading channels is investigated where the source and destination communicate with each other through direct and indirect links. Only the performance of best relay is investigated which participates in the transmission alone. The relay node that achieves highest SNR at the destination is selected as a best relay. Once again our analysis shows that full diversity order can be achieved with single relay with fewer resources compare to the regular cooperative diversity system.Muhammad Adeel Islam 0046 700 412 343
36
Amoedo, Diego Alves, and 69-98468-0910. "Classificação automática de modulações mono e multiportadoras utilizando método de extração de características e classificadores SVM." Universidade Federal do Amazonas, 2017. http://tede.ufam.edu.br/handle/tede/6176.
Full textAbstract:
Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-02-23T14:45:53Z
No. of bitstreams: 2
Dissertação_Diego A. Amoedo.pdf: 21597862 bytes, checksum: a9e7494163dfed228afe8750f777a7fc (MD5)
license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-02-23T14:46:21Z (GMT) No. of bitstreams: 2 Dissertação_Diego A. Amoedo.pdf: 21597862 bytes, checksum: a9e7494163dfed228afe8750f777a7fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
Made available in DSpace on 2018-02-23T14:46:21Z (GMT). No. of bitstreams: 2 Dissertação_Diego A. Amoedo.pdf: 21597862 bytes, checksum: a9e7494163dfed228afe8750f777a7fc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-07-19
Cognitive radio is a new technology that aims to solve the spectrumunderutilization problem, through spectrum sensing, whose objective is to detect the so called spectrum holes. Automatic modulation classi cation plays an important role in this scenario, since it provides information about primary users, with the goal of aiding in spectrum sensing tasks. In the present dissertation, we propose a methodology for multiclass and hierarchical classi cation of modulated signal using support vector machines (SVM), with a set of prede ned parameters. In literature, other works deal with automatic modulation classi cation with SVM and other classi ers, however, few of them take a deep look at classi er design. SVM is known by its high discrimantion capacity, but its performance is very sensitive to the parameters used during classi ers design. With the use of a prede ned set of parameters, we seek to analyze the behavior of the classi er broadly and to investigate the in uence of parameter changes on the constitution of classi ers. In addition, we use one-versus-all and one-versus-one, error-correcting output codes and hierarchical decomposition. Finally, nine types of modulations (AM, FM, BPSK, QPSK, 16QAM, 64QAM, GMSK, OFDM and WCDMA) are used. The types of modulation as well as the decomposition techniques used cover almost all decomposition techniques and modulation classes present in the literature.
O Rádio Cognitivo é uma nova tecnologia que busca resolver o problema de subutilização do espectro de radiofrequências, por meio do sensoriamento do espectro, cujo objetivo é detectar os buracos espectrais. A classi cação automática de modulação desempenha um papel importante neste cenário, pois, provém informa- ção sobre os usuários primários de modo a auxiliar nas tarefas de sensoriamento do espectro. Nesta dissertação, propomos uma metodologia para a classi cação multiclasse e hierárquica de sinais modulados utilizando SVM, com um conjunto de parâmetros pré-de nidos. Na literatura, outros trabalhos tratam da classi cação automática de modulação tanto com SVM como com outros tipos de classi cadores, porém, poucos fazem uma análise detalhada do projeto dos classi cadores. O SVM é conhecido por sua alta capacidade de discriminação, todavia, seu desempenho é bastante sensível aos parâmetros usados na geração dos classi cadores. Com a utilização de um conjunto pré-de nido de parâmetros, buscamos analisar o comportamento do classi cador de forma ampla e investigar a in uência das mudanças de parâmetros na constituição de classi cadores. Além disso, utiliza-se as técnicas de decomposição multiclasse um-contra-todos, um-contra-um, códigos de saída corretores de erros e hierárquica. Por m, foram utilizados nove tipos de modulações (AM, FM, BPSK, QPSK, 16QAM, 64QAM, GMSK, OFDM e WCDMA). Tanto os tipos de modulação quanto as técnicas de decomposição abrangem quase a totalidade de técnicas de decomposição e de classes de modulação presentes na literatura.
37
Chouaba, Seif Eddine. "Contribution à l'estimation des modèles linéaires à paramètres variants à temps continu. Application à la modélisation des échangeurs de chaleur." Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2257/document.
Full textAbstract:
Le travail de recherche présenté dans ce mémoire est une contribution à l'estimation des modèles Linéaires à Paramètres Variants (LPV) à temps continu. Dans un premier temps, il traite de façon originale la modélisation quasi-LPV des échangeurs de chaleur pour la détection d'encrassement durant les régimes transitoires. La méthodologie définie dans cette thèse est introduite pas à pas pour caractériser un échangeur à courants croisés puis pour celle d'un échangeur à contre-courants montrant ainsi la généricité de l'approche pour la modélisation des échangeurs thermiques. Une méthode locale basée sur une estimation initiale de modèles LTI en différents points du domaine de fonctionnement est utilisée pour construire le modèle LPV en agrégeant les paramètres des différents modèles locaux grâce à une méthode d'interpolation polynomiale liée aux débits massiques. Le modèle quasi-LPV de l'échangeur élaboré en fonctionnement sain permet ainsi d'envisager la détection de l'encrassement dans les échangeurs de chaleur en comparant ses sorties à ceux provenant du procédé. Dans un second temps, ce travail porte sur l'identification des systèmes LPV à représentation entrée-sortie à temps continu par une approche globale. Une solution pratique pour l'identification directe de tels systèmes est proposée. Elle est basée sur l'utilisation d'un algorithme à erreur de sortie initialisé par une approche à erreur d'équation, la méthode des Moments Partiels Réinitialisés. Des simulations illustrent les performances de l'approche proposéeThe research work presented in this thesis is a contribution to the estimation of Linear Parameter Varying (LPV) models in continuous-time. First, a quasi-LPV modeling of heat exchangers is tackled in an original way. This quasi-LPV model is meant to be used for fouling detection (during transient phases). A step-by-step description of the methodology is given on how to model a cross flow heat exchanger. Applying the same approach on a counter flow shows its genericity in the heat exchanger field. A local method, based on an estimation of LTI models for different operating points, is used to build the LPV model by interpolation of the various LTI model parameters. The resulting quasi-LPV model for a clean heat exchanger can thus be used for fouling detection by comparison of real and model outputs for the same input signals. Secondly, this work concerns the identification of continuous-time input-output LPV systems through a global approach. A practical solution for the direct identification of such systems is proposed. It is based on the use of an output-error algorithm initialized by an equation error based approach, the reinitialized partial moment's method. Simulations illustrate the performance of the proposed approach
38
Tran, Nguyen Duy. "Performance bounds in terms of estimation and resolution and applications in array processing." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00777503.
Full textAbstract:
This manuscript concerns the performance analysis in signal processing and consists into two parts : First, we study the lower bounds in characterizing and predicting the estimation performance in terms of mean square error (MSE). The lower bounds on the MSE give the minimum variance that an estimator can expect to achieve and it can be divided into two categories depending on the parameter assumption: the so-called deterministic bounds dealing with the deterministic unknown parameters, and the so-called Bayesian bounds dealing with the random unknown parameter. Particularly, we derive the closed-form expressions of the lower bounds for two applications in two different fields: (i) The first one is the target localization using the multiple-input multiple-output (MIMO) radar in which we derive the lower bounds in the contexts with and without modeling errors, respectively. (ii) The other one is the pulse phase estimation of X-ray pulsars which is a potential solution for autonomous deep space navigation. In this application, we show the potential universality of lower bounds to tackle problems with parameterized probability density function (pdf) different from classical Gaussian pdf since in X-ray pulse phase estimation, observations are modeled with a Poisson distribution. Second, we study the statistical resolution limit (SRL) which is the minimal distance in terms of the parameter of interest between two signals allowing to correctly separate/estimate the parameters of interest. More precisely, we derive the SRL in two contexts: array processing and MIMO radar by using two approaches based on the estimation theory and information theory. We also present in this thesis the usefulness of SRL in optimizing the array system.
39
Cortes-Pena, Luis Miguel. "Optimizing dense wireless networks of MIMO links." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52254.
Full textAbstract:
Wireless communication systems have exploded in popularity over the past few decades. Due to their popularity, the demand for higher data rates by the users, and the high cost of wireless spectrum, wireless providers are actively seeking ways to improve the spectral efficiency of their networks. One promising technique to improve spectral efficiency is to equip the wireless devices with multiple antennas. If both the transmitter and receiver of a link are equipped with multiple antennas, they form a multiple-input multiple-output (MIMO) link.
The multiple antennas at the nodes provide degrees-of-freedom that can be used for either sending multiple streams of data simultaneously (a technique known as spatial multiplexing), or for suppressing interference through linear combining, but not both. Due to this trade-off, careful allocation of how many streams each link should carry is important to ensure that each node has enough degrees-of-freedom available to suppress the interference and support its desired streams. How the streams are sent and received and how interference is suppressed is ultimately determined by the beamforming weights at the transmitters and the combining weights at the receivers. Determining these weights is, however, made difficult by their inherent interdependency.
Our focus is on unplanned and/or dense single-hop networks, such as WLANs and femtocells, where each single-hop network is composed of an access point serving several associated clients. The objective of this research is to design algorithms for maximizing the performance of dense single-hop wireless networks of MIMO links. We address the problems of determining which links to schedule together at each time slot, how many streams to allocate to each link (if any), and the beamforming and combining weights that support those streams.
This dissertation describes four key contributions as follows:
- We classify any interference suppression technique as either unilateral interference suppression or bilateral interference suppression. We show that a simple bilateral interference suppression approach outperforms all known unilateral interference suppression approaches, even after searching for the best unilateral solution.
- We propose an algorithm based on bilateral interference suppression whose goal is to maximize the sum rate of a set of interfering MIMO links by jointly optimizing which subset of transmitters should transmit, the number of streams for each transmitter (if any), and the beamforming and combining weights that support those streams.
- We propose a framework for optimizing dense single-hop wireless networks. The framework implements techniques to address several practical issues that arise when implementing interference suppression, such as the overhead of performing channel measurements and communicating channel state information, the overhead of computing the beamforming and combining weights, and the overhead of cooperation between the access points.
- We derive the optimal scheduler that maximizes the sum rate subject to proportional fairness.
Simulations in ns-3 show that the framework, using the optimal scheduler, increases the proportionally fair aggregate goodput by up to 165% as compared to the aggregate goodput of 802.11n for the case of four interfering single-hop wireless networks with two clients each.
40
Thomas, Robin Rajan. "Optimisation of adaptive localisation techniques for cognitive radio." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/27076.
Full textAbstract:
Spectrum, environment and location awareness are key characteristics of cognitive radio (CR). Knowledge of a user’s location as well as the surrounding environment type may enhance various CR tasks, such as spectrum sensing, dynamic channel allocation and interference management. This dissertation deals with the optimisation of adaptive localisation techniques for CR. The first part entails the development and evaluation of an efficient bandwidth determination (BD) model, which is a key component of the cognitive positioning system. This bandwidth efficiency is achieved using the Cramer-Rao lower bound derivations for a single-input-multiple-output (SIMO) antenna scheme. The performances of the single-input-single-output (SISO) and SIMO BD models are compared using three different generalised environmental models, viz. rural, urban and suburban areas. In the case of all three scenarios, the results reveal a marked improvement in the bandwidth efficiency for a SIMO antenna positioning scheme, especially for the 1×3 urban case, where a 62% root mean square error (RMSE) improvement over the SISO system is observed. The second part of the dissertation involves the presentation of a multiband time-of arrival (TOA) positioning technique for CR. The RMSE positional accuracy is evaluated using a fixed and dynamic bandwidth availability model. In the case of the fixed bandwidth availability model, the multiband TOA positioning model is initially evaluated using the two-step maximum-likelihood (TSML) location estimation algorithm for a scenario where line-of-sight represents the dominant signal path. Thereafter, a more realistic dynamic bandwidth availability model has been proposed, which is based on data obtained from an ultra-high frequency spectrum occupancy measurement campaign. The RMSE performance is then verified using the non-linear least squares, linear least squares and TSML location estimation techniques, using five different bandwidths. The proposed multiband positioning model performs well in poor signal-to-noise ratio conditions (-10 dB to 0 dB) when compared to a single band TOA system. These results indicate the advantage of opportunistic TOA location estimation in a CR environment.Dissertation (MEng)--University of Pretoria, 2012.
Electrical, Electronic and Computer Engineering
unrestricted
41
Amate, Jorge Farid. "Modelos Polinomiais para Detecção de Efeito Anódico." Universidade Federal do Maranhão, 2009. http://tedebc.ufma.br:8080/jspui/handle/tede/414.
Full textAbstract:
Made available in DSpace on 2016-08-17T14:53:03Z (GMT). No. of bitstreams: 1
Jorge Farid Amate.pdf: 1076998 bytes, checksum: 7c54d6bc2833288f1945368aa6976936 (MD5)
Previous issue date: 2009-02-06Conselho Nacional de Desenvolvimento Científico e Tecnológico
In industrial processes, where parameters estimation and standard recognition are desired, digital filters technology is used to do estimation. The digital filter is responsible for prediction and filtering process. Then, the filter behavior can be analyzed based on performance, gains and others variables linked to the specified model. However, to obtain trusty variables and data to estimate the process in question, a model that represents well the physics plant is needed. To do this, are applied techniques based on Systems Identification where we obtain the ARX, ARMAX, Output-Error and Box-Jenkins models of the electrolytic pot. Results, validation and their analysis, applied in standard recognition, using different structures are presented.
Em processos industriais, onde deseja-se a estimação de parâmetros e reconhecimento de padrões, utiliza-se da tecnologia de filtros digitais para tal fim. O filtro digital é responsável pelo processo de predição e filtragem. Assim, pode-se fazer uma análise do comportamento do filtro baseada no desempenho, ganhos e outras variáveis ligadas ao modelo especificado. Porém, para obtenção de variáveis e dados confiáveis para estimar-se o processo em questão, necessita-se de um modelo que represente bem a planta física. Para isto, são aplicadas técnicas baseadas em Identificação de Sistemas, onde são obtidos os modelos ARX, ARMAX, Output-Error e Box-Jenkins da cuba eletrolítica. São apresentados os resultados, validações dos modelos e análise dos mesmos, aplicados ao reconhecimento de padrões, utilizando-se diferentes estruturas.
42
Baysse, Arnaud. "Contributions à l'identification paramétrique de modèles à temps continu : extensions de la méthode à erreur de sortie, développement d'une approche spécifique aux systèmes à boucles imbriquées." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0047/document.
Full textAbstract:
Les travaux de recherche présentés dans ce mémoire concernent des contributions à l'identification paramétrique de modèles à temps continu. La première contribution est le développement d'une méthode à erreur de sortie appliquée à des modèles linéaires, en boucle ouverte et en boucle fermée. Les algorithmes sont présentés pour des modèles à temps continu, en utilisant une approche hors ligne ou récursive. La méthode est étendue à l'identification de systèmes linéaires comprenant un retard pur. La méthode développée est appliquée à différents systèmes et comparée aux méthodes d'identification existantes. La deuxième contribution est le développement d'une nouvelle approche d'identification de systèmes à boucles imbriquées. Cette approche est développée pour l'identification de systèmes électromécaniques. Elle se base sur l'utilisation d'un modèle d'identification paramétrique générique d'entraînements électromécaniques en boucle fermée, sur la connaissance du profil des lois de mouvement appliquées appelées excitations, et sur l'analyse temporelle de signaux internes et leurs corrélations avec les paramètres à identifier. L'approche est développée dans le cadre de l'identification d'entraînements à courant continu et synchrone. L'application de cette approche est effectuée au travers de simulations et de tests expérimentaux. Les résultats sont comparés à des méthodes d'identification classiquesThe research works presented in this thesis are about contributions in continuous time model parametric identication. The rst work is the development of an output error method applied on linear models, in open and closed loop. The algorithms are presented for continuous time models, using in-line or oine approaches. The method is extended to the case of the linear systems containing pure time delay. The developed method is applied to several systems and compared to the best existing methods. The second contribution is the development of a new identication approach for cascaded loop systems. This approach is developed for identifying electromechanical systems. It is based on the use of a generic parametric model of electromechanical drives in closed loop, on the knowledge of the movement laws applied and called excitations, and on the analyse of the time internal signals and their correlations with the parameters to identify. This approach is developed for identifying direct current and synchronous drives. The approach is applied with simulations and experimental tests. The obtained results are compared to best identifying known methods
43
Balasubramanian, Ravishankar. "Adjoint-based error estimation and grid adaptation for functional outputs from CFD simulations." Diss., Mississippi State : Mississippi State University, 2005. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.
Full text
44
Balsubramanian, Ravishankar. "Error estimation and grid adaptation for functional outputs using discrete-adjoint sensitivity analysis." Master's thesis, Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-10032002-113749.
Full text
45
Ozkinaci, Mehmet Erdal. "Finding Malformed Html Outputs And Unhandled Execution Errors Of Asp.net Applications." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613199/index.pdf.
Full textAbstract:
As dynamic web applications are becoming widespread nearly in every area, ASP.NET is one of the popular development languages in this domain. The errors in these web applications can reduce the credibility of the site and cause possible loss of a number of clients. Therefore, testing these applications becomes significant. We present an automated tool to test ASP.NET web applications against execution errors and HTML errors that cause displaying inaccurate and incomplete information. Our tool, called Mamoste, adapts concolic testing technique which interleaves concrete and symbolic executions to generate test inputs dynamically. Mamoste also considers page events as inputs which cannot be handled with concolic testing. We have performed experiments on a subset of an heavily used ASP.NET application of a government office. We have found 366 HTML errors and a faulty component which is used almost every ASP.NET page in this application. In addition, Mamoste discovered that a common user control is misused in several generated pages.
46
Nasser, Eddine Achraf. "Modélisation fractionnaire et identification d'impédance d'accumulateurs électrochimiques." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2307.
Full textAbstract:
L’impédance d’un accumulateur électrochimique est principalement caractérisée par trois phénomènes : la conduction électronique, le transfert de charge et la diffusion ionique. La modélisation de ces phénomènes fait intervenir des fonctions de transfert non rationnelles et non directement simulables dans le domaine temporel. Leur approximation par des modèles fractionnaires (ou modèles d’ordre non entier) devient alors judicieuse pour estimer les caractéristiques de l’impédance à partir non seulement de mesures fréquentielles (spectroscopie), mais aussi de mesures temporelles (chronopotentiométrie). La chronopotentiométrie permet en effet de s’affranchir des contraintes de la spectroscopie pour laquelle les mesures nécessitent un équipement plus complexe et des durées d’acquisition plus longues, en particulier aux basses fréquences. Des stratégies d’identification de ces modèles ont été développées et appliquées expérimentalement sur une cellule électrochimique de type Ferri ferrocyanure ainsi que sur des accumulateurs Lithium-ion et Nickel Métal-Hydrure. Les essais de caractérisation de ces éléments sont effectués à différents états de charge et les résultats obtenus montrent l’intérêt et la pertinence de la méthodologie utiliséeThe impedance of an electrochemical accumulator is mainly characterized by three phenomena: the electronic conduction, the charge transfer and the ionic diffusion. The modeling of these phenomena involves non-rational transfer functions that cannot be directly simulated in the time domain. Then, their approximation by fractional models (also known as non-integer order models) becomes relevant to estimate the impedance characteristics from not only frequency measurements (spectroscopy), but also time measurements (chronopotentiometry). Moreover, the long-time required by the spectroscopy to measure at low frequencies, as well as the complexity of the equipment used can be avoided by using chronopotentiometry. Models identification strategies have been developed and validated experimentally on a Ferri ferrocyanide electrochemical cell, on Lithium-ion and on Nickel Metal-Hydride accumulators. The characterization tests of these elements are carried out at different states of charge and obtained results show the interest and the relevance of the methodology
47
Domingues, Tiago Paixão Moreira. "Forecasting unemployment errors by the troika : evidence from the adjustment programmes for Greece." Master's thesis, Instituto Superior de Economia e Gestão, 2017. http://hdl.handle.net/10400.5/14675.
Full textAbstract:
Mestrado em Economia Monetária e FinanceiraO objetivo desta dissertação é o de estudar os erros na previsão do desemprego que estão presentes nos programas de ajustamento para a economia grega. O estudo começa por uma revisão teórica dos principais aspectos relacionados com as interacções entre a política monetária e fiscal na Zona Euro com especial atenção ao caso da Grécia. De seguida, utilizei duas metodologias para testar a performance das previsões feitas pela Troika: O modelo Vector Error Correcting (VEC) e o modelo Leontief Input-Output. Foi encontrada evidencia para o modelo econométrico subestimar o desemprego, como sugerido nas previsões da Troika, mas ainda assim com mais precisão quando comparado com as previsões apresentadas nos programas de ajustamento. Em contraste, o modelo IO tende a sobrestimar o desemprego para o mesmo período. Contudo, depois de ajustado para os dados da Organização para a Cooperação e Desenvolvimento Económico (OCDE), a sua performance é substancialmente melhorada. É possível concluir que tal boom no desemprego seria relativamente difícil de prever, especialmente através de simples técnicas econométricas, mas poderia ter sido melhor entendido através de uma análise sectorial como aquela que foi aplicada neste trabalho.
The aim of this dissertation is to study the unemployment errors present in the troika´s economic adjustment programs for the Greek economy. I start by reviewing theoretical aspects of the fiscal and monetary interactions in the European Monetary Union (EMU) and the particular case of Greece. Then, I use two methodologies to test the performance of troika?s economic adjustment programs: a Vector Error Correcting (VEC) model and the Leontief Input-Output (IO) model. I found evidence for the econometric model to underestimate unemployment, as troika's forecasts did, but with a slightly higher accuracy when compared to troika's programs. In contrast, the Input-Output application tends to overestimate the unemployment rate for the same period. However, after adjusting to the figures available from the Organization for Economic and Cooperation and Development (OECD), its performance is substantially improved. We conclude that such unemployment boom was relatively hard to predict, especially when using simple standard econometric techniques, but it could have been better assessed with an inter-sectoral analysis such as the one we apply in this work.
info:eu-repo/semantics/publishedVersion
48
Guerberof, Arenas Ana. "Productivity and quality in the post-editing of outputs from translation memories and machine translation." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/90247.
Full textAbstract:
This study presents empirical research on no-match, machine-translated and translation-memory segments, analyzed in terms of translators’ productivity, final quality and prior professional experience. The findings suggest that translators have higher productivity and quality when using machine-translated output than when translating on their own, and that the productivity and quality gained with machine translation are not significantly different from the values obtained when processing fuzzy matches from a translation memory in the 85-94 percent range. The translators’ prior experience impacts on the quality they deliver but not on their productivity. These quantitative findings are triangulatedwith qualitative data from an online questionnaire and from one-to-one debriefings with the translators.
Este estudio presenta una investigación empírica sobre la traducción de segmentos nuevos y aquellos procesados con traducción automática y memorias de traducción analizados en relación a la productividad, calidad final y experiencia profesional de un grupo de traductores. Los resultados sugieren que los traductores obtienen una productividad y calidad más altas cuando procesan segmentos de traducción automática que cuando traducen sin ninguna ayuda y que dicha productividad y calidad no son significativamente diferentes a la que se obtiene cuando procesan coincidencias parciales de una memoria de traducción (del 85 al 94 por ciento). La experiencia profesional previa de los traductores influye en la calidad pero no así en la productividad obtenidas. Los resultados cuantitativos se triangulan, además, con datos cualitativos obtenidos a través de un cuestionario en línea y de entrevistas individuales realizadas a los trad
49
Shang, Lei, and lei shang@ieee org. "Modelling of Mobile Fading Channels with Fading Mitigation Techniques." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20061222.113303.
Full textAbstract:
This thesis aims to contribute to the developments of wireless communication systems. The work generally consists of three parts: the first part is a discussion on general digital communication systems, the second part focuses on wireless channel modelling and fading mitigation techniques, and in the third part we discuss the possible application of advanced digital signal processing, especially time-frequency representation and blind source separation, to wireless communication systems. The first part considers general digital communication systems which will be incorporated in later parts. Today's wireless communication system is a subbranch of a general digital communication system that employs various techniques of A/D (Analog to Digital) conversion, source coding, error correction, coding, modulation, and synchronization, signal detection in noise, channel estimation, and equalization. We study and develop the digital communication algorithms to enhance the performance of wireless communication systems. In the Second Part we focus on wireless channel modelling and fading mitigation techniques. A modified Jakes' method is developed for Rayleigh fading channels. We investigate the level-crossing rate (LCR), the average duration of fades (ADF), the probability density function (PDF), the cumulative distribution function (CDF) and the autocorrelation functions (ACF) of this model. The simulated results are verified against the analytical Clarke's channel model. We also construct frequency-selective geometrical-based hyperbolically distributed scatterers (GBHDS) for a macro-cell mobile environment with the proper statistical characteristics. The modified Clarke's model and the GBHDS model may be readily expanded to a MIMO channel model thus we study the MIMO fading channel, specifically we model the MIMO channel in the angular domain. A detailed analysis of Gauss-Markov approximation of the fading channel is also given. Two fading mitigation techniques are investigated: Orthogonal Frequency Division Multiplexing (OFDM) and spatial diversity. In the Third Part, we devote ourselves to the exciting fields of Time-Frequency Analysis and Blind Source Separation and investigate the application of these powerful Digital Signal Processing (DSP) tools to improve the performance of wireless communication systems.
50
Koeslag, Francois. "A detailed analysis of the imperfections of pulsewidth modulated waveforms on the output stage of a class D audio amplifier." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/3972.
Full textAbstract:
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.Although the Class D topology offers several advantages, its use in audio amplification has previously been limited by the lack of competitiveness in fidelity compared to its linear counterparts. During the past decade, technological advances in semiconductor technology have awakened new interest since competitive levels of distortion could now be achieved. The output stage of such an amplifier is the primary limiting factor in its performance. In this dissertation, four non-ideal effects existing in this stage are identified and mathematically analysed. The analytical analysis makes use of a well-established mathematical model, based on the double Fourier series method, to model the imperfections introduced into a naturally sampled pulsewidth modulated waveform. The analysis is complemented by simulation using a strategy based on Newton’s numerical method. The theory is verified by a comparison between the analytical-, simulated- and experimental results.