Dissertations / Theses on the topic 'Space and time Design'
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Feldgoise, Jeffrey. "Thermal design through space and time." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/65983.
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Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1997.Includes bibliographical references (p. 89-90).
One of the primary roles of architecture is to control the environment at the service of a building's inhabitants. Thermal qualities are a significant factor in the overall experience one has inside and outside a building. However, thermal issues are not often considered within the context of the architectural design process, resulting in buildings that are not responsive to thermal concerns. Heat has the potential to influence the form of architectural space. The methods by which architects can use thermal energy as a formative element in design is open to further exploration. In this thesis, I explore new methods for architects to describe thermal intentions and visualize thermal qualities of design proposals. Beyond the economic issue of energy conservation, the thermal qualities of building spaces affect the quality of human inhabitation. The capability to describe and visualize heat would allow architects to adjust the building's thermal characteristics to modify a person's experience of the place. With a more complete understanding of thermal qualities of their building proposals, architects would be able to design for the complete gamut of thermal sensations that humans can experience. What is needed is a working vocabulary that describes the range of thermal conditions possible in buildings. In this work, I describe a vocabulary for a building's thermal qualities using four sets of measurable, opposing terms: open versus protected, bright versus dim, warm versus cool, and active versus still. Next, I then articulate the thermal qualities of a co-housing project to create a thermal experience that enhances the community aspects of co-housing. Using a variety of visualization techniques, I verify that the design proposal is achieving the intended thermal goals. Using the knowledge gained from this and future thermal design exercises, we can begin to reflect on the general relationships between thermal phenomena and physical building forms, learning about the thermal qualities of architecture.
Jeffrey Feldgoise.
M.Arch.
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Rouchy, Christophe. "Systematic Design of Space-Time Convolutional Codes." Thesis, University of California, Santa Cruz, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1554232.
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Space-time convolutional code (STCC) is a technique that combines transmit diversity and coding to improve reliability in wireless fading channels. In this proposal, we demonstrate a systematic design of multi-level quadrature amplitude modulation (M-QAM) STCCs utilizing quadrature phase shift keying (QPSK) STCC as component codes for any number of transmit antennas. Morever, a low complexity decoding algorithm is introduced, where the decoding complexity increases linearly by the number of transmit antennas. The approach is based on utilizing a group interference cancellation technique also known as combined array processing (CAP) technique.
Finally, our research topic will explore: with the current approach, a scalable STTC with better performance as compared to space- time block code (STBC) combined with multiple trellis coded modulation (MTCM) also known as STBC-MTCM; the design of low complexity decoder for STTC; the combination of our approach with multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM).
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Chopra, Sanjay. "Class hierarchy design for space time problems." Master's thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-10312009-020024/.
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Fitriani. "Multiscale Dynamic Time and Space Warping." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45279.
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Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2008.Includes bibliographical references (p. 149-151).
Dynamic Time and Space Warping (DTSW) is a technique used in video matching applications to find the optimal alignment between two videos. Because DTSW requires O(N4) time and space complexity, it is only suitable for short and coarse resolution videos. In this thesis, we introduce Multiscale DTSW: a modification of DTSW that has linear time and space complexity (O(N)) with good accuracy. The first step in Multiscale DTSW is to apply the DTSW algorithm to coarse resolution input videos. In the next step, Multiscale DTSW projects the solution from coarse resolution to finer resolution. A solution for finer resolution can be found effectively by refining the projected solution. Multiscale DTSW then repeatedly projects a solution from the current resolution to finer resolution and refines it until the desired resolution is reached. I have explored the linear time and space complexity (O(N)) of Multiscale DTSW both theoretically and empirically. I also have shown that Multiscale DTSW achieves almost the same accuracy as DTSW. Because of its efficiency in computational cost, Multiscale DTSW is suitable for video detection and video classification applications. We have developed a Multiscale-DTSW-based video classification framework that achieves the same accuracy as a DTSW-based video classification framework with greater than 50 percent reduction in the execution time. We have also developed a video detection application that is based on Dynamic Space Warping (DSW) and Multiscale DTSW methods and is able to detect a query video inside a target video in a short time.
by Fitriani.
S.M.
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Roggenkamp, Chrystal R. "Spatial Promenades: Sequential Experiences in Space and Time." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1306499060.
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Zhang, Tingting. "Space time transceiver design over multipath fading channels." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11964.
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The objective of the study is to develop novel space-time transceivers for OS-COMA (DirectSequence Code Division Multiple Access) arrayed MIMO (Multiple-Input Multiple-Output) systems operating in multiple-access multipath fading channels. The ever increasing demand for performance and capacity in cellular wireless systems has prompted the development of OS-COMA MIMO systems. Unlike other reported research on MIMO systems which often .assumes the use of multiple antennas, in this thesis, arrayed MIMO system frameworks are proposed, which, by harnessing the geometrical information of the antenna arrays and received signals, provide a richer description of the channel characteristics and additional degrees offreedom in designing communication systems. Firstly, the framework of MIMO arrayed system in a OS-COMA system is developed. Subspace type blind channel estimator and receiver based on Doppler Spatial-Temporal Array (Doppler-STAR) are developed for time varying frequency selective fading channels, providing the system with more accurate channel estimation, higher resolution and superior interference cancellation capabilities. Secondly, joint transmitter and receiver optimisation in multipath and multiple access downlink system is studied. The two dimensional Spatio-Temporal Array manifold matrix (STAR matrix) is introduced. An iterative and a closed-form solution are proposed to solve the optimisation problem of minimising the MSE over the entire network. The proposed schemes offer a performance advantage over transmitter only (Tx-beamforming) and receiver only (Rx-beamforming) beamforming techniques under the system framework. Finally, the framework of an OFOM-CDMA arrayed system is developed. With the aid of Circular Spatial-Temporal ARray (C-STAR) manifold vector, two types of receivers (Le. preFFT and post.;FFT) are proposed-to eliminate the effect of multiple access interference (MAl) and inter-symbol interference (lSI) in a comp,letely blind way.
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Guo, Xiaoyong. "Space-time code design for wireless communication systems." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 168 p, 2010. http://proquest.umi.com/pqdweb?did=1992441381&sid=9&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Vilaipornsawai, Usa. "Space-time coding and receiver design for unknown time-varying wireless channels." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66767.
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This thesis considers a joint channel estimation and data detection algorithm for Multiple Space-Time Trellis Codes (MSTTCs) over high Doppler fading channels. This algorithm belongs to the Per-Survivor Processing (PSP) family, where a survivor associated with a trellis state is used for channel estimation. We propose a smoothed data detection technique to increase the probability of the survivor being a correct data sequence. A symbol by symbol Maximum A Posteriori Probability (MAP) criterion, with a fixed delay $D$, is employed for data detection, combined with a Kalman Predictor (KP) for channel estimation. This novel algorithm, called Smoothed Data Detection and Kalman Estimation (SDD-KE), provides a significant performance gain when $D>0$ over $D=0$, with a linear increase in complexity when $D$ increases. Comparison with the Delayed Mixture Kalman Filtering (DMKF) technique shows that the SDD-KE algor ithm provides important performance and complexity advantages. Motivated by the fact that all joint channel estimation and data detection schemes suffer from the phase ambiguity problem, we developed a design method that can transform any phase ambiguity prone STTC into a Phase Ambiguity Diminishing STTC (PAD-STTC). A PAD-STTC can be considered as an MSTTC with special constellation mappings. The design criteria for these mappings are developed by trading among the PAD property, diversity, and coding gain. Two PAD-STTC structures termed PAD1-STTC and PAD2-STTC are proposed, where PAD2-STTC increases the number of states over the constituent STTC. Computer simulation results indicate that PAD-STTCs can solve the phase ambiguity problem and provide a larger diversity gain than the constituent STTC over high Doppler fading channels. Moreover, with the same constituent STTC, the PAD2-STTC outperforms the PAD1-STTC at the expense of increased complexity. This thesis also develops a joint channel estimationCette thése présente une méthode conjointe d'estimation de voie et de détection de données pour les codes multiples espace-temps en treillis (MSTTCs) sur des canauxà évanouissement avec gros effet Doppler. Cette méthode se base sur le principe du "traitement par survivant" (PSP), oùà chaque état du treillis, le chemin survivant est utilisé pour l'estimation de voie. Nous proposons une technique de détection de données lissées pour augmenter la probabilité que le survivant correspondeà la bonne séquence de données. Le processus de détection utilise le critére du maximum de probabilitéà posteriori (MAP) symbole par symbole avec un délai fixe $D$, tandis que le processus d'estimation se base sur un prédicteur de Kalman. Ce nouvel algorithme est appelé Détection de Données Lissées et Estimation Kalman (SDD-KE). Pour $D>0$, des gains significatifs sont obtenus comparativementà $D=0$, et la complexité de l'algorithme augmente linéairement avec $D$. D'autre part, comparéà la technique du Delayed Mixture Kalman Filter (DMKF), notre approche permet d'importantes améliorations en terme de performance et de complexité.Motivés par le fait que le probléme d'ambiguité sur les phases est communà toute méthode conjointe d'estimation de voie et de détection de données, nous avons developpé une méthode de conception capable de transformer n'importe quel STTC en un nouvel STTC Réduisant l'Ambiguité sur les Phases (PAD-STTC). Un PAD-STTC est en fait un MSTTC avec des mappages de constellation particuliers. Les critéres de conception de ces mappages sont obtenues en tenant compte de la réduction du probléme d'ambiguité sur les phases ainsi que des gains de diversité et de codage. Deux structures PAD-STTCs nommées PAD1-STTC et PAD2-STTC sont proposées, avec la distinction que PAD2-STTC utilise un plus grand nombre d'états que le STTC corresponda
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Karacayir, Murat. "Space-time Codes." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612028/index.pdf.
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The phenomenon of fading constitutes a fundamental problem in wireless communications. Researchers have proposed many methods to improve the reliability of communication over wireless channels in the presence of fading. Many studies on this topic have focused on diversity techniques. Transmit diversity is a common diversity type in which multiple antennas are employed at the transmitter. Space-time coding is a technique based on transmit diversity introduced by Tarokh et alii in 1998.
In this thesis, various types of space-time codes are examined. Since they were originally introduced in the form of trellis codes, a major part is devoted to space-time trellis codes where the fundamental design criteria are established. Then, space-time block coding, which presents a different approach, is introduced and orthogonal spacetime block codes are analyzed in some detail. Lastly, rank codes from coding theory
are studied and their relation to space-time coding are investigated.
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Alam, Syed Asad. "Design Space Exploration of Time-Multiplexed FIRFilters on FPGAs." Thesis, Linköping University, Department of Electrical Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54287.
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FIR (Finite-length Impulse Response) filters are the corner stone of many signalprocessing devices. A lot of research has gone into their development as wellas their effective implementation. With recent research focusing a lot on powerconsumption reduction specially with regards to FPGAs, it was found necessaryto explore FIR filters mapping on FPGAs.
Time multiplexed FIR filters are also a good candidate for examination withrespect to power consumption and resource utilization, for example when implementedin Field Programmable Gate Arrays (FPGAs). This is motivated by thefact that the usable clock frequency often is higher compared to the required datarate. Current implementations by, e.g., Xilinx FIR Compiler suffer from highpower consumption when the time multiplexing factor is low. Further, it needs tobe investigated how exploiting coefficient symmetry, scaling the coefficients andincreasing the time-multiplexing factor influences the performance.
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Ding, Zhiguo. "Receiver algorithm design for space time block coding systems." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420523.
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Sanders, Ralph Jarrett. "Space, time, and silence." Thesis, Virginia Polytechnic Institute and State University, 1990. http://hdl.handle.net/10919/56200.
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This thesis is a meditation upon silence, upon its ontological relationship to architecture. As such, it relies more upon insight and contemplation than analysis. It seeks to explore this realm through the making of a trappist monastery, to ask fundamental questions about the nature of human dwelling in the most complete sense, to stir the memory and perhaps to move the heart toward that silence which is beyond thought, which precedes and bounds and yet pervades all human experience.Master of Architecture
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Joshi, Prachi. "Design Space Exploration for Embedded Systems in Automotives." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82839.
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With ever increasing contents (safety, driver assistance, infotainment, etc.) in today's automotive systems that rely on electronics and software, the supporting architecture is integrated by a complex set of heterogeneous data networks. A modern automobile contains up to 100 ECUs and several heterogeneous communication buses (such as CAN, FlexRay, etc.), exchanging thousands of signals. The automotive Original Equipment Manufacturers (OEMs) and suppliers face a number of challenges such as reliability, safety and cost to incorporate the growing functionalities in vehicles. Additionally, reliability, safety and cost are major concerns for the industry.
One of the important challenges in automotive design is the efficient and reliable transmission of signals over communication networks such as CAN and CAN-FD. With the growing features in automotives, the OEMs already face the challenge of saturation of bus bandwidth hindering the reliability of communication and the inclusion of additional features. In this dissertation, we study the problem of optimization of bandwidth utilization (BU) over CAN-FD networks. Signals are transmitted over the CAN/CAN-FD bus in entities called frames. The signal-to-frame-packing has been studied in the literature and it is compared to the bin packing problem which is known to be NP-hard.
By carefully optimizing signal-to-frame packing, the CAN-FD BU can be reduced. In Chapter 3, we propose a method for offset assignment to signals and show its importance in improving BU. One of our contributions for an industrial setting is a modest improvement in BU of about 2.3%. Even with this modest improvement, the architecture's lifetime could potentially be extended by several product cycles, which may translate to saving millions of dollars for the OEM. Therefore, the optimization of signal-to-frame packing in CAN-FD is the major focus of this dissertation. Another challenge addressed in this dissertation is the reliable mapping of a task model onto a given architecture, such that the end-to-end latency requirements are satisfied. This avoids costly redesign and redevelopment due to system design errors.Ph. D.
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Haddadin, Baker. "Time domain space mapping optimization of digital interconnect circuits." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116004.
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Microwave circuit design including the design of Interconnect circuits are proving to be a very hard and complex process where the use of CAD tools is becoming more essential to the reduction in design time and in providing more accurate results. Space mapping methods, the relatively new and very efficient way of optimization which are used in microwave filters and structures will be investigated in this thesis and applied to the time domain optimization of digital interconnects. The main advantage is that the optimization is driven using simpler models called coarse models that would approximate the more complex fine model of the real system, which provide a better insight to the problem and at the same time reduce the optimization time. The results are always mapped back to the real system and a relation/mapping is found between both systems which would help the convergence time. In this thesis, we study the optimization of interconnects where we build certain practical error functions to evaluate performance in the time domain. The space mapping method is formulated to avoid problems found in the original formulation where we apply some necessary modifications to the Trust Region Aggressive Space Mapping TRASM for it to be applicable to the design process in time domain. This new method modified TRASM or MTRASM is then evaluated and tested on multiple circuits with different configuration and the results are compared to the results obtained from TRASM.
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Yadav, A. (Animesh). "Space-time constellation and precoder design under channel estimation errors." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526202143.
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Abstract Multiple-input multiple-output transmitted signal design for the partially coherent Rayleigh fading channels with discrete inputs under a given average transmit power constraint is consider in this thesis. The objective is to design the space-time constellations and linear precoders to adapt to the degradation caused by the imperfect channel estimation at the receiver and the transmit-receive antenna correlation. The system is partially coherent so that the multiple-input multiple-output channel coefficients are estimated at the receiver and its error covariance matrix is fed back to the transmitter. Two constellation design criteria, one for the single and another for the multiple transmit antennae are proposed. An upper bound on the average bit error probability for the single transmit antenna and cutoff rate, i.e., a lower bound on the mutual information, for multiple transmit antennae are derived. Both criteria are functions of channel estimation error covariance matrix. The designed constellations are called as partially coherent constellation. Additionally, to use the resulting constellations together with forward error control codes requires efficient bit mapping schemes. Because these constellations lack geometrical symmetry in general, the Gray mapping is not always possible in the majority of the constellations obtained. Moreover, different mapping schemes may lead to highly different bit error rate performances. Thus, an efficient bit mapping algorithm called the modified binary switching algorithm is proposed. It minimizes an upper bound on the average bit error probability. It is shown through computer simulations that the designed partially coherent constellation and their optimized bit mapping algorithm together with turbo codes outperform the conventional constellations. Linear precoder design was also considered as a simpler, suboptimal alternative. The cutoff rate expression is again used as a criterion to design the linear precoder. A linear precoder is obtained by numerically maximizing the cutoff rate with respect to the precoder matrix with a given average transmit power constraint. Furthermore, the precoder matrix is decomposed using singular-value-decomposition into the input shaping, power loading, and beamforming matrices. The beamforming matrix is found to coincide with the eigenvectors of the transmit correlation matrix. The power loading and input shaping matrices are solved numerically using the difference of convex functions programming algorithm and optimization under the unitary constraint, respectively. Computer simulations show that the performance gains of the designed precoders are significant compared to the cutoff rate optimized partially coherent constellations without precodingTiivistelmä Väitöskirjassa tarkastellaan lähetyssignaalien suunnittelua osittain koherenteissa Rayleigh-häipyvissä kanavissa toimiviin monitulo-monilähtöjärjestelmiin (MIMO). Lähettimen keskimääräinen lähetysteho oletetaan rajoitetuksi ja lähetyssignaali diskreetiksi. Tavoitteena on suunnitella tila-aikakonstellaatioita ja lineaarisia esikoodereita jotka mukautuvat epätäydellisen kanavaestimoinnin aiheuttamaan suorituskyvyn heikkenemiseen sekä lähetin- ja vastaanotinantennien väliseen korrelaatioon. Tarkasteltavien järjestelmien osittainen koherenttisuus tarkoittaa sitä, että MIMO-kanavan kanavakertoimet estimoidaan vastaanottimessa, josta niiden virhekovarianssimatriisi lähetetään lähettimelle. Työssä esitetään kaksi konstellaatiosuunnittelukriteeriä, toinen yhdelle lähetinantennille ja toinen moniantennilähettimelle. Molemmat kriteerit ovat kanavan estimaatiovirheen kovarianssimatriisin funktioita. Työssä johdetaan yläraja keskimääräiselle bittivirhetodennäköisyydelle yhden lähetinantennin tapauksessa sekä rajanopeus (cutoff rate), joka on alaraja keskinäisinformaatiolle, usean lähetinantennin tapauksessa. Konstellaatioiden käyttö yhdessä virheenkorjauskoodien kanssa edellyttää tehokaita menetelmiä, joilla bitit kuvataan konstellaatiopisteisiin. Koska tarvittavat konstellaatiot eivät ole tyypillisesti geometrisesti symmetrisiä, Gray-kuvaus ei ole yleensä mahdollinen.Lisäksi erilaiset kuvausmenetelmät voivat johtaa täysin erilaisiin bittivirhesuhteisiin. Tästä johtuen työssä esitetään uusi kuvausalgoritmi (modified bit switching algorithm), joka minimoi keskimääräisen bittivirhetodennäköisyyden ylärajan. Simulointitulokset osoittavat, että työssä kehitetyt konstellaatiot antavat paremman suorituskyvyn turbokoodatuissa järjestelmissä kuin perinteiset konstellaatiot. Työssä tarkastellaan myös lineaarista esikoodausta yksinkertaisena, alioptimaalisena vaihtoehtona uusille konstellaatioille. Esikoodauksen suunnittelussa käytetään samaa kriteeriä kuin konstellaatioiden kehityksessä eli rajanopeutta. Lineaarinen esikooderi löydetään numeerisesti maksimoimalla rajanopeus kun rajoitusehtona on lähetysteho. Esikoodausmatriisi hajotetaan singulaariarvohajotelmaa käyttäen esisuodatus, tehoallokaatio ja keilanmuodostusmatriiseiksi, jonka havaitaan vastaavan lähetyskorrelaatiomatriisin ominaisvektoreita. Tehoallokaatiomatriisi ratkaistaan numeerisesti käyttäen difference of convex functions -optimointia ja esisuodatusmatriisi optimoinnilla unitaarista rajoitusehtoa käyttäen. Simulaatiotulokset osoittavat uusien esikoodereiden tarjoavan merkittävän suorituskykyedun sellaisiin rajanopeusoptimoituihin osittain koherentteihin konstellaatioihin nähden, jotka eivät käytä esikoodausta
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Hesse, Matthias. "L2-orthogonal space-time code design for continuous phase modulation." Nice, 2010. http://www.theses.fr/2010NICE4008.
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Orthogonal Space-Time block codes (STBC) have been a popular way to implement wireless communications systems with full diversity and simple decoupled maximum-likelihood decoding. However, all these codes rely on pointwise orthogonality which leads to a well-known degradation of data rate for more than two antennas. In this thesis, we introduce the concept of L2-orthogonality for non-linear Space-Time codes (STC). Our approach generalizes code design based on pointwise orthogonality. Hence, we are able to derive new codes with the same advantages as pointwise orthogonal STBC, i. E. Low decoding complexity and diversity gain. At the same time, we are no longer limited by the restrictions of pointwise orthogonal codes, namely the reduction in data rate. Actually, we show how to construct full rate codes for any arbitrary number of transmit antennas. More precisely, a family of codes for continuous phase modulation (CPM) is detailed. The L2-orthogonality of these codes is ensured by a bank of phase correction functions which maintains the phase continuity but also introduces frequency offsets. We prove that these codes achieve full diversity and have full rate. Moreover, these codes don't put any restriction on the CPM parametersLes codes spatio-temporels orthogonaux par blocs (OSTBC) sont devenus populaires en ce qu'ils permettent de construire des systèmes de communications sans-fil à diversité maximale et à décodage simplifié par maximum de vraisemblance découplé. Cependant, ces codes reposent en général sur une orthogonalité ponctuelle, ce qui entraîne une dégradation bien connue du débit de transmission pour les systèmes à plus de deux antennes d'émission. Nous introduisons dans cette thèse le concept d'orthogonalité L2 pour les codes spatio-temporel (STC). Cette approche permet de généraliser naturellement la propriété d'orthogonalité ponctuelle pour des systèmes à codages spatio-temporels non-linéaires. Il devient alors possible de construire de nouveaux systèmes multi-antennes (MIMO) à faible complexité de décodage et gain de diversité maximal. De plus, contrairement aux systèmes reposant sur des codes linéaires orthogonaux, ces nouveaux systèmes ne présentent plus de limitation du débit de transmission pour plus de deux antennes. Nous détaillons la construction générale de diverses familles de codes spatio-temporels L2 à débit maximal reposant sur des modulations de phase continue (CPM) et ceci pour n'importe quel nombre d'antennes d'émission. L'orthogonalité L2 des systèmes construits est obtenue par un banc de fonctions de correction de phase qui induit la diversité par décalage en fréquence tout en maintenant la continuité de la phase pour chaque antenne. L'étude de ces codes permet de démontrer que les systèmes MIMO à décodage simplifié ainsi obtenus sont à diversité maximale et débit optimal. Enfin, notons que la construction de ces codes n'introduit aucune contrainte supplémentaire sur les paramètres des modulations de phase continue utilisées
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Jing, Yindi Doyle John Comstock. "Space-time code design and its applications in wireless networks /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-07232004-075729.
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dalton, timothy. "A Space for Absence." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1660.
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This thesis focuses on the evolution of my work created during my two years of study at Virginia Commonwealth University. Although I touch upon my influences what I am writing is a reflection after the fact that does not necessarily encompass my original intent or inspirations for these works. I find my inspiration from personal discoveries within my daily life. Light flickering through the rails of a fence as I walk by makes me more aware of my body's movement in space. Watching the steady condensation of water droplets forming on a fountain creates a moment of pause within the world. Through these discoveries preconceptions about the world are forgotten and instead I focus on my experience. The potential for translating these moments into installations for an audience fuels my work. Though everyone experiences the world differently the pursuit of a common ground creates situations for further discoveries. The process of writing this paper has helped me to find a common thread within my work. Thinking back through the experiential discoveries of each piece has furthered my understanding, just as it originally propelled my artistic productio
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Garcia-Albarado, J. Cruz. "Natural patterns in time and space : inspiration for ecological planting design." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419280.
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Distretti, Emilio. "Materialities in circulation : Italy and its colonies across time and space." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/materialities-in-circulation(3c9d9bcd-035d-44fb-b25d-fc9891e57a52).html.
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In the context of Italian colonialism, relations between the colonisers and the colonised have often been constructed and conducted through materialities (objects, things and artefacts) as means for the transmission, exchange and exercise of power. Practices of architecture, infrastructure and spoliation have then created and intensified systems of circulation connecting the metropole to the periphery. Along this axis the movement of materialities justified the colonial order within a capitalist system of production, trade, migration, communication and conquest. This dissertation interrogates the relationship between ‘materiality’ and ‘circulation’ as central categories of analysis that allow the evaluation of Italian colonialism as a historical event and the deciphering of the complexities of Italy’s post-colonial present. It offers an in-depth analysis of specific materialities that from the earlier phases of Italian colonisation in the Horn of Africa and Libya up to the post-colonial present have circulated between Italy and its colonies, tying the centre to the periphery. This thesis reveals that as a parallel to the movement of humans between the metropole and the colonies, between the Global North and the Global South, an ensemble of materialities – road infrastructure, an obelisk, anthropometric artefacts and skeletal remains - seem to be epistemologically crucial in describing power relations between the colonisers and the colonised in both the colonial and post-colonial epochs. Formerly instrumental for civilisational claims of Italian superiority in relation to native populations, since decolonisation these materialities have turned into objects of dispute, emblems of postcolonial identities and bargaining chips for posthumous justice for colonial violence and pillage. Within such a context, the discourse on memory and the elaboration of the colonial past together with the definition of new power relations and techniques of government over ‘others’ – migration policies, development and humanitarianism – constantly develop while revolving around those same materialities that, in the first place, served the purposes of the colonial mission.
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Fleming, Andrew. "Real-time optimal slew maneuver design and control." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1197.
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Approved for public release; distribution in unlimited.This thesis considers the problem of time-optimal spacecraft slew maneuvers. Since the work of Bilimoria and Wie it has been known that the time-optimal reorientation of a symmetric rigid body was not the eigenaxis maneuver once thought to be correct. Here, this concept is extended to axisymmetric and asymmetric rigid body reorientations with idealized independent torque generating devices. The premise that the time-optimal maneuver is not, in general, an eigenaxis maneuver, is shown to hold for all spacecraft configurations. The methodology is then extended to include spacecraft control systems employing magnetic torque rods, a combination of pitch bias wheel with magnetic torque rods, and finally to control systems employing single gimbal control moment gyros. The resulting control solutions, designed within the limitations of the actuators, eliminate the requirement to avoid actuator singularities. Finally, by employing sampled-state feedback the viability of real-time optimal closed loop control is demonstrated.
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Chen, Tzu. "Light Force: An Exploration of Light Through Design." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32314.
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Nieh, Jo-Yen. "A systematic approach to design of space-time block coded MIMO systems." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FNieh.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2006.Thesis Advisor(s): Murali Tummala. "June 2006." Includes bibliographical references (p.103-104). Also available in print.
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Wang, Dong. "Space-time trellis code design with simple decoding for MIMO communication systems." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.87 Mb., 156 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3200526.
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Khan, Muhammad Kalimuddin. "The design of high rate space-time LDPC codes for IEEE 802.16d." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437935.
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Aktas, Defne. "Improved peformance measures for space-time coding with applications to code design /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486546889382825.
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Mohd, Sayuti M. Norazizi Sham. "Early design space exploration of hard real-time embedded networks-on-chip." Thesis, University of York, 2014. http://etheses.whiterose.ac.uk/8963/.
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Networks-On-Chip (NoC) is seen as a solution for addressing the limitation of the current bus-based communication in embedded systems. Some of these systems are designed for executing hard real-time services. In such systems, the services have to deliver output within strict timing constraints since the lateness in output delivery could cause severe consequences to human life. Task mapping is a crucial step for integrating an application and a hardware platform during system design. Existing schedulability analyses are available to evaluate the hard real-time performance of task mapping, but exploring the vast number of task mappings at the early design stage can be challenging due to several issues. These issues are caused by the influence of other design parameters on the hard real-time performance produced by task mapping, the existence of conflicting design objectives with the hard real-time system constraints, the restriction of the current hard real-time evaluation functions for searching alternative task mappings and the enormous evaluation of population-based search heuristics in the current task mapping techniques. This thesis proposes several design space exploration techniques to address these issues. The first technique is proposed for addressing the problem of optimising multiple design parameters while keeping all tasks and messages in the system fully schedulable. The second technique addresses the conflicting objectives problem using a multi-objective optimisation approach. The third technique yields a new metric that is useful for improving task mappings with unschedulable tasks and messages. Finally, the last technique is a new mapping algorithm for constructing a feasible task mapping rather than have to evaluate a population of task mappings to achieve the same objective.
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Grabner, Mitchell J. "A Cognitive MIMO OFDM Detector Design for Computationally Efficient Space-Time Decoding." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1538696/.
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In this dissertation a computationally efficient cognitive multiple-input multiple-output (MIMO) orthogonal frequency division duplexing (OFDM) detector is designed to decode perfect space-time coded signals which are able maximize the diversity and multiplexing properties of a rich fading MIMO channel. The adaptive nature of the cognitive detector allows a MIMO OFDM communication system to better meet to needs of future wireless communication networks which require both high reliability and low run-time complexity depending on the propagation environment. The cognitive detector in conjunction with perfect space-time coding is able to achieve up to a 2 dB bit-error rate (BER) improvement at low signal-to-noise ratio (SNR) while also achieving comparable runtime complexity in high SNR scenarios.
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Panagos, Adam G., and Kurt Kosbar. "A METHOD FOR FINDING BETTER SPACE-TIME CODES FOR MIMO CHANNELS." International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/604782.
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ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, NevadaMultiple-input multiple output (MIMO) communication systems can have dramatically higher throughput than single-input, single-output systems. Unfortunately, it can be difficult to find the space-time codes these systems need to achieve their potential. Previously published results located good codes by minimizing the maximum correlation between transmitted signals. This paper shows how this min-max method may produce sub-optimal codes. A new method which sorts codes based on the union bound of pairwise error probabilities is presented. This new technique can identify superior MIMO codes, providing higher system throughput without increasing the transmitted power or bandwidth requirements.
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Hertel, Thorsten Walter. "Analysis and design of conical spiral antennas in free space and over ground." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/15018.
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Parsafard, Mohsen. "Space-Time Transportation System Modelling: from Traveler’s Characteristics to the Network Design Problem." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6924.
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Traditional network design problems only consider the long-term stationary travel patterns (e.g., fixed OD demand) and short-term variations of human mobility are ignored. This study aims to integrate human mobility characteristics and travel patterns into network design problems using a space-time network structure. Emerging technologies such as location-based social network platforms provide a unique opportunity for understanding human mobility patterns that can lead to advanced modeling techniques. To reach our goal, at first multimodal network design problems are investigated by considering safety and flow interactions between different modes of transport. We develop a network reconstruction method to expand a single-modal transportation network to a multi-modal network where flow interactions between different modes can be quantified. Then, in our second task, we investigate the trajectory of moving objects to see how they can reveal detailed information about human travel characteristics and presence probability with high-resolution detail. A time geography-based methodology is proposed to not only estimate an individual’s space-time trajectory based on his/her limited space-time sample points but also to quantify the accuracy of this estimation in a robust manner. A series of measures including activity bandwidth and normalized activity bandwidth are proposed to quantify the accuracy of trajectory estimation, and cutoff points are suggested for screening data records for mobility analysis.
Finally, a space-time network-based modeling framework is proposed to integrate human mobility into network design problems. We construct a probabilistic network structure to quantify human’s presence probability at different locations and time. Then, a Mixed Integer Nonlinear Programming (MINLP) model is proposed to maximize the spatial and temporal coverage of individual targets. To achieve near optimal solutions for large-scale problems, greedy heuristic, Lagrangian relaxation and simulated annealing algorithms are implemented to solve the problem. The proposed algorithms are implemented on hypothetical and real world numerical examples to demonstrate the performance and effectiveness of the methodology on different network sizes and promising results have been obtained.
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Varadarajan, Badri. "The Design of Linear Space-Time Codes for Quasi-static Flat-fading Channels." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5030.
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The reliability and data rate of wireless communication have traditionally been limited by the presence of multipath fading in wireless channels. However, dramatic performance improvements can be obtained by the use of multiple transmit and receive antennas. Specifically, multiple antennas increase reliability by providing diversity gain, namely greater immunity to deep channel fades. They also increase data rates by providing multiplexing gain, i.e., the ability to multiplex multiple symbols in one signaling interval.
Harvesting the potential benefits of multiple antennas requires the use of specially designed space-time codes at the transmitter front-end. Space-time codes introduce redundancy in the transmitted signal across two dimensions, namely multiple transmit antennas and multiple signaling intervals. In this work, we focus on linear space-time codes, which linearly combine the real and imaginary parts of their complex inputs to obtain transmit vectors for multiple signaling intervals.
We aim to design optimum linear space-time codes. Optimality metrics and design principles for space-time codes are shown to depend strongly on the codes' function in the overall transmitter architecture. We consider two cases, depending on whether or not the space-time code is complemented by a powerful outer error-control code.
In the absence of an outer code, the multiplexing gain of a space-time code is measured by its rate, while its diversity gain is measured by its raw diversity order. To maximize multiplexing and diversity gains, the space-time code must have maximum possible rate and raw diversity order. We show that there is an infinite set of maximum-rate codes, almost all of which also have maximum raw diversity order. However, different codes in this set have different error rate for a given input alphabet and SNR. Therefore, we develop analytical and numerical optimization techniques to find the code in this set which has the minimum union bound on error rate. Simulation results indicate that optimized codes yield significantly lower error rates than unoptimized codes, at the same data rate and SNR.
In a concatenated architecture, a powerful outer code introduces redundancy in the space-time code inputs, obtaining additional diversity. Thus, the raw diversity order of the space-time inner code is only a lower limit to the total diversity order of the concatenated transmitter. On the other hand, we show that the rate of the space-time code places an upper limit on the multiplexing ability of the concatenated architecture. We conclude that space-time inner codes should have maximum possible rate but need not have high raw diversity order. In particular, the serial-to-parallel converter, which introduces no redundancy at all, is a near-optimum space-time inner code. This claim is supported by simulation results.
On the receiver side, we generalize the well known sphere decoder to develop new detection algorithms for stand-alone space-time codes. These new algorithms are extended to obtain efficient soft-output decoding algorithms for space-time inner codes.
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Iltis, Ronald A. "Adaptive Space-Time Waveform Design in Ad hoc Networks using the IMMSE Algorithm." International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/605789.
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International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, CaliforniaAn Ad hoc network with unicasting is considered, in which each node has an M element antenna array. Transmission from node l(i) to i is quasi-synchronous, so that code acquisition is not required. Space-Time (S-T) waveforms are transmitted with temporal dimension Ns Nyquist samples. An adaptive, distributed S-T waveform design algorithm is developed, which maintains QoS while attempting to minimize transmit power. The resulting Iterative Minimum Mean-Square Error{Time Reversal algorithm (IMMSE-TR) sets the transmit S-T vector at node i to the conjugate time-reverse of the linear MMSE S-T detector. It is shown that IMMSE-TR corresponds to a noncooperative game which attempts to minimize transmit power while paying an interference tax. Simulation results are presented demonstrating high power efficiencies for heavily-loaded systems.
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Giroudot, Frédéric. "NoC-based Architectures for Real-Time Applications : Performance Analysis and Design Space Exploration." Thesis, Toulouse, INPT, 2019. https://oatao.univ-toulouse.fr/25921/1/Giroudot_Frederic.pdf.
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Les architectures mono-processeur montrent leurs limites en termes de puissance de calcul face aux besoins des systèmes actuels. Bien que les architectures multi-cœurs résolvent partiellement ce problème, elles utilisent en général des bus pour interconnecter les cœurs, et cette solution ne passe pas à l'échelle. Les architectures dites pluri-cœurs ont été proposées pour palier les limitations des processeurs multi-cœurs. Elles peuvent réunir jusqu'à des centaines de cœurs sur une seule puce, organisés en dalles contenant une ou plusieurs entités de calcul. La communication entre les cœurs se fait généralement au moyen d'un réseau sur puce constitué de routeurs reliés les uns aux autres et permettant les échanges de données entre dalles. Cependant, ces architectures posent de nombreux défis, en particulier pour les applications temps-réel. D'une part, la communication via un réseau sur puce provoque des scénarios de blocage entre flux, ce qui complique l'analyse puisqu'il devient difficile de déterminer le pire cas. D'autre part, exécuter de nombreuses applications sur des systèmes sur puce de grande taille comme des architectures pluri-cœurs rend la conception de tels systèmes particulièrement complexe. Premièrement, cela multiplie les possibilités d'implémentation qui respectent les contraintes fonctionnelles, et l'exploration d'architecture résultante est plus longue. Deuxièmement, une fois une architecture matérielle choisie, décider de l'attribution de chaque tâche des applications à exécuter aux différents cœurs est un problème difficile, à tel point que trouver une une solution optimale en un temps raisonnable n'est pas toujours possible. Ainsi, nos premières contributions s'intéressent à cette nécessité de pouvoir calculer des bornes fiables sur le pire cas des latences de transmission des flux de données empruntant des réseaux sur puce dits "wormhole". Nous proposons un modèle analytique, BATA, prenant en compte la taille des mémoires tampon des routeurs et applicable à une configuration de flux de données périodiques générant un paquet à la fois. Nous étendons ensuite le domaine d'applicabilité de BATA pour couvrir un modèle de traffic plus général ainsi que des architectures hétérogènes. Cette nouvelle méthode, appelée G-BATA, est basée sur une structure de graphe pour capturer les interférences possibles entre flux de données. Elle permet également de diminuer le temps de calcul de l'analyse, améliorant la capacité de l'approche à passer à l'échelle. Dans une seconde partie, nous proposons une méthode pour la conception d'applications temps-réel s'exécutant sur des plateformes pluri-cœurs. Cette méthode intègre notre modèle d'analyse G-BATA dans un processus de conception systématique, faisant en outre intervenir un outil de modélisation et de simulation de systèmes reposant sur des concepts d'ingénierie dirigée par les modèles, TTool, et un logiciel pour l'analyse de performance pire-cas des réseaux, WoPANets. Enfin, nous proposons une validation de nos contributions grâce à (a) une série d'expériences sur une plateforme physique et (b) deux études de cas d'applications réelle; le système de contrôle d'un véhicule autonome et une application de décodeur 5GMonoprocessor architectures have reached their limits in regard to the computing power they offer vs the needs of modern systems. Although multicore architectures partially mitigate this limitation and are commonly used nowadays, they usually rely on intrinsically non-scalable buses to interconnect the cores. The manycore paradigm was proposed to tackle the scalability issue of bus-based multicore processors. It can scale up to hundreds of processing elements (PEs) on a single chip, by organizing them into computing tiles (holding one or several PEs). Intercore communication is usually done using a Network-on-Chip (NoC) that consists of interconnected onchip routers allowing communication between tiles. However, manycore architectures raise numerous challenges, particularly for real-time applications. First, NoC-based communication tends to generate complex blocking patterns when congestion occurs, which complicates the analysis, since computing accurate worst-case delays becomes difficult. Second, running many applications on large Systems-on-Chip such as manycore architectures makes system design particularly crucial and complex. On one hand, it complicates Design Space Exploration, as it multiplies the implementation alternatives that will guarantee the desired functionalities. On the other hand, once a hardware architecture is chosen, mapping the tasks of all applications on the platform is a hard problem, and finding an optimal solution in a reasonable amount of time is not always possible. Therefore, our first contributions address the need for computing tight worst-case delay bounds in wormhole NoCs. We first propose a buffer-aware worst-case timing analysis (BATA) to derive upper bounds on the worst-case end-to-end delays of constant-bit rate data flows transmitted over a NoC on a manycore architecture. We then extend BATA to cover a wider range of traffic types, including bursty traffic flows, and heterogeneous architectures. The introduced method is called G-BATA for Graph-based BATA. In addition to covering a wider range of assumptions, G-BATA improves the computation time; thus increases the scalability of the method. In a second part, we develop a method addressing design and mapping for applications with real-time constraints on manycore platforms. It combines model-based engineering tools (TTool) and simulation with our analytical verification technique (G-BATA) and tools (WoPANets) to provide an efficient design space exploration framework. Finally, we validate our contributions on (a) a serie of experiments on a physical platform and (b) two case studies taken from the real world: an autonomous vehicle control application, and a 5G signal decoder application
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Holdar, Magdalena. "Scenography in Action : Space, Time and Movement in Theatre Productions by Ingmar Bergman." Doctoral thesis, Stockholm : Konstvetenskapliga institutionen, Stockholms universitet, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-427.
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Owojaiye, Gbenga Adetokunbo. "Design and performance analysis of distributed space time coding schemes for cooperative wireless networks." Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/8970.
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In this thesis, space-time block codes originally developed for multiple antenna systems are extended to cooperative multi-hop networks. The designs are applicable to any wireless network setting especially cellular, adhoc and sensor networks where space limitations preclude the use of multiple antennas. The thesis first investigates the design of distributed orthogonal and quasi-orthogonal space time block codes in cooperative networks with single and multiple antennas at the destination. Numerical and simulation results show that by employing multiple receive antennas the diversity performance of the network is further improved at the expense of slight modification of the detection scheme. The thesis then focuses on designing distributed space time block codes for cooperative networks in which the source node participates in cooperation. Based on this, a source-assisting strategy is proposed for distributed orthogonal and quasi-orthogonal space time block codes. Numerical and simulation results show that the source-assisting strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs.Motivated by the problem of channel state information acquisition in practical wireless network environments, the design of differential distributed space time block codes is investigated. Specifically, a co-efficient vector-based differential encoding and decoding scheme is proposed for cooperative networks. The thesis then explores the concatenation of differential strategies with several distributed space time block coding schemes namely; the Alamouti code, square-real orthogonal codes, complex-orthogonal codes, and quasiorthogonal codes, using cooperative networks with different number of relay nodes. In order to cater for high data rate transmission in non-coherent cooperative networks, differential distributed quasi-orthogonal space-time block codes which are capable of achieving full code-rate and full diversity are proposed. Simulation results demonstrate that the differential distributed quasi-orthogonal space-time block codes outperform existing distributed space time block coding schemes in terms of code rate and bit-error-rate performance. A multidifferential distributed quasi-orthogonal space-time block coding scheme is also proposed to exploit the additional diversity path provided by the source-destination link.A major challenge is how to construct full rate codes for non-coherent cooperative broadband networks with more than two relay nodes while exploiting the achievable spatial and frequency diversity. In this thesis, full rate quasi-orthogonal codes are designed for noncoherent cooperative broadband networks where channel state information is unavailable. From this, a generalized differential distributed quasi-orthogonal space-frequency coding scheme is proposed for cooperative broadband networks. The proposed scheme is able to achieve full rate and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of the proposed scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, sufficient conditions are derived for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity. In order to exploit the additional diversity paths provided by the source-destination link, a novel multidifferential distributed quasi-orthogonal space-frequency coding scheme is proposed. The overall objective of the new scheme is to improve the quality of the detected signal at the destination with negligible increase in the computational complexity of the detector.Finally, a differential distributed quasi-orthogonal space-time-frequency coding scheme is proposed to cater for high data rate transmission and improve the performance of noncoherent cooperative broadband networks operating in highly mobile environments. The approach is to integrate the concept of distributed space-time-frequency coding with differential modulation, and employ rotated constellation quasi-orthogonal codes. From this, we design a scheme which is able to address the problem of performance degradation in highly selective fading environments while guaranteeing non-coherent signal recovery and full code rate in cooperative broadband networks. The coding scheme employed in this thesis relaxes the assumption of constant channel variation in the temporal and frequency dimensions over long symbol periods, thus performance degradation is reduced in frequencyselective and time-selective fading environments. Simulation results illustrate the performance of the proposed differential distributed quasi-orthogonal space-time-frequency coding scheme under different channel conditions.
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Ben-Asher, Joseph Z. "Time optimal slewing of flexible spacecraft." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53910.
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The time optimal slewing problem for flexible spacecraft is considered. We study single-axis rotational maneuvers for a simple flexible system, consisting of a rigid hub with an elastic appendage. The equations of motions are derived by Hamilton’s Principle, and a discrete nonlinear model is obtained by the assumed modes method. The problem is first solved in a discrete linearized space by parameter optimization. Optimality is verified by Pontryagin’s Maximum Principle. The linear solutions are then used to obtain time optimal solutions for the non-linear problem by a multiple-shooting algorithm. Although this approach is applicable to arbitrary boundary conditions, this work is confined, almost exclusively, to rest-to-rest maneuvers. These maneuvers are shown to possess some interesting symmetric and asymptotic properties. The problem is further analyzed in infinite-dimensional space, and the convergence of the finite-dimensional approximations is studied. Finally, a soft version of the time optimal slewing problem is considered, where the control is bounded only by a penalty term in the cost functional. A perturbation technique is applied to further simplify this problem.Ph. D.
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Chen, Junying, and 陈俊颖. "Design space exploration of real-time bedside and portable medical ultrasound adaptive beamformer acceleration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B50434354.
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This work explored the design considerations on the real-time medical ultrasound adaptive beamformer implementations using different computing platforms: CPU, GPU and FPGA. Adaptive beamforming has been well considered as an advanced solution for improving the image quality of medical ultrasound imaging machines. Although it provides promising improvements in lateral resolution, image contrast and imaging penetration depth, the use of adaptive beamforming is substantially more computationally demanding than conventional delay-and-sum beamformers. In order not to compromise the real-time performance of medical ultrasound systems, an accelerated solution is desirable.
In this work, CPU implementation was used as a baseline implementation, based on which the intrinsic characteristics of the algorithm were analyzed. After the analysis of a particular adaptive beamforming algorithm, minimum-variance adaptive beamforming, two design parameters M and L were found to affect the implementation performance in two aspects: computational demand and image quality. The trends of the two aspects were contradictory with respect to the increment of M and L values. In our experiments, when M and L increased, the computational demand increased in a cubic curve; meanwhile, the image quality did not have much improvement when the increased values of M and L entered certain ranges. Since we targeted at a real-time solution without sacrificing the good image quality that adaptive beamforming proposed, a tradeoff was made on the selection of M and L values to balance the two contradictory requirements.
Built upon the theoretical algorithmic analysis of the real-time adaptive beamformer realization, the implementations were developed with FPGA and GPU. While a dedicated hardware solution might be able to address the computational demand of the particular design, the need for an efficient algorithm exploration framework demanded a reprogrammable platform solution that was high-performance and easily reconfigurable. Besides, although a simple processor could provide convenient algorithm exploration via software development environment, real-time performance was usually not achievable. As a result, a reprogrammable medical ultrasound research platform for investigating advanced imaging algorithms was constructed in our project. The use of FPGA and GPU for implementing the real-time adaptive beamformer on our platform was explored. In our test cases, both FPGA- and GPUbased solutions achieved real-time throughput exceeding 80 frames-per-second, and over 38x improvement when compared to our baseline CPU implementation.
Moreover, the implementations were also evaluated in terms of portability, data accuracy, programmability, and system integration. Due to its high power consumption, high-performance GPU solution is best suited for bedside applications, while FPGAs are more suitable for portable and hand-held medical ultrasound machines. Besides, while the development time on GPU platform remains much lower than its FPGA counterpart, the FPGA solution is effective in providing the necessary I/O bandwidth to enable an end-to-end real-time reconfigurable medical ultrasound image formation system.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Hemadeh, Ibrahim. "Transceiver design for millimetre-wave communications : a space-time-frequency multi-functional processing approach." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/418979/.
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In this thesis, we investigate a suite of transceiver designs for transmission over millimetre wave (mmWave) channels. Furthermore, we conceive the philosophy of Layered Multi-Group (LMG) arrangements relying on the concept of Multi-Functional Multiple- Input Multi-Output (MF-MIMO) systems. More specifically, we propose an amalgam of various MIMO techniques, namely diversity, multiplexing and beamforming techniques as well as Multi-User MIMO (MU-MIMO), user grouping and antenna layering methods, which are capable of simultaneously gleaning various MIMO advantages for the sake of overcoming the unfavourable propagation characteristics of mmWave signals. The mm- Wave channel suffers both from high path loss and sparse scattering, which results in reduced receiver diversity. To mitigate these problems, we propose the LMG Steered Space-Time Shift Keying (LMG-SSTSK) system. More specifically, the LMG-SSTSK system is capable of achieving an enhanced multiplexing gain and an improved diversity gain by relying on STSK, and a beamforming gain with the aid of analogue beamforming. Additionally, LMG-SSTSK is capable of supporting multi-user communication using MU Transmit Precoding (MUTPC) as well as an increased number of served users with the aid of sophisticated antenna layering and user grouping. We opt for STSK as the main transmission scheme, since it is an MF-MIMO, which is capable striking a design trade-off between the achievable throughput and the attainable diversity gain. Additionally, the system employs Orthogonal Frequency-Division Multiplexing (OFDM) for transmitting over the mmWave wideband channel, which imposes frequency selective fading due to its high bandwidth, where time dispersion is imposed by the delay of the sparse multipath components. The above-mentioned antenna grouping and user grouping concepts were introduced into the LMG-SSTSK system in order to overcome the restrictions imposed by the mmWave channel in MU scenarios, where due to the high path loss and the beamforming employed, the system cannot simultaneously support angularly dispersed users. Hence, the users are partitioned into groups and the proposed MF-MIMO communicates with all users by conceiving antenna layering. On the other hand, in order to enhance the LMG-SSTSK’s achievable throughput, we propose the novel Multi-Set Space-Time Shift Keying (MS-STSK) scheme. The MSSTSK system constitutes an improved version of STSK and has the potential of outperforming other MIMO arrangements by appropriately choosing the MS-STSK’s parameters. In MS-STSK, a single dispersion matrix is activated using a classical PSK/QAM symbol and transmitted by activating a single Antenna Combination (AC), where an AC is defined as a unique set of multiple antenna elements out of those available at the transmitter. The achievable throughput of MS-STSK depends on the AC allocation technique employed. Hence, the Distinct Antenna Allocation (DAC) technique and the Shared Antenna Allocation (SAC) technique are conceived. The DAC technique requires a distinct set of antenna elements in each antenna combination, while the antenna elements are shared among the available ACs with the aid of SAC, hence MS-STSK associated with DAC achieves an enhanced performance at the cost of a reduced throughput compared to its SAC counterpart, which strikes a design trade-off between them. Furthermore, in order to transmit over the mmWave channel, we intrinsically amalgamate both OFDM and analogue beamforming with MS-STSK using our OFDM-aided MS-STSK system, leading to our OFDM-MS-STSK system. We further exploit the frequency dimension for enhancing the achievable throughput of the OFMD-aided MS-STSK system by introducing the Multi-Space-Frequency STSK (MSF-STSK) system. Accordingly, we introduce our MU Steered MS-STSK (MU-SMS-STSK) system by employing MU-TPC in OFDMMS- STSK for simultaneously supporting multiple users. Finally, to mitigate the angular selectivity of the beamforming-aided mmWave channel, we reintroduce the LMG structure in the LMG-SMS-STSK arrangement. Additionally, in order to achieve near-capacity performance using the classical MSSTSK scheme, we conceive a serially-concatenated channel coding assisted MS-STSK scheme. More specifically, we devise a soft-decision-aided MS-STSK decoder associated with an iterative two-stage serially-concatenated inner detector and outer decoder, which is designed by relying on EXtrinsic Information Transfer (EXIT) charts. Finally, in order to transmit over the mmWave channel, our soft-decision-aided scheme is combined with wideband techniques, such as OFDM and Single-Carrier Frequency Division Equalisation (SC-FDE), as well as beamforming, where due to the DFT and IDFT mismatch introduced by OFDM, we opt for SC-FDE to retain the advantage of MS-STSK having to rely on a reduced number of RF-chains.
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Kobayashi, Minoru. "Design of dynamic soundscape : mapping time to space for audio browsing with simultaneous listening." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/29117.
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Rezaiesarlak, Reza. "Design and Detection Process in Chipless RFID Systems Based on a Space-Time-Frequency Technique." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73506.
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Recently, Radio Frequency Identification (RFID) technology has become commonplace in many applications. It is based on storing and remotely retrieving the data embedded on the tags. The tag structure can be chipped or chipless. In chipped tags, an integrated IC attached to the antenna is biased by an onboard battery or interrogating signal. Compared to barcodes, the chipped tags are expensive because of the existence of the chip. That was why chipless RFID tags are demanded as a cheap candidate for chipped RFID tags and barcodes. As its name expresses, the geometry of the tag acts as both modulator and scatterer. As a modulator, it incorporates data into the received electric field launched from the reader antenna and reflects it back to the receiving antenna. The scattered signal from the tag is captured by the antenna and transferred to the reader for the detection process.
By employing the singularity expansion method (SEM) and the characteristic mode theory (CMT), a systematic design process is introduced by which the resonant and radiation characteristics of the tag are monitored in the pole diagram versus structural parameters. The antenna is another component of the system. Taking advantage of ultra-wideband (UWB) technology, it is possible to study the time and frequency domain characteristics of the antenna used in chipless RFID system. A new omni-directional antenna element useful in wideband and UWB systems is presented. Then, a new time-frequency technique, called short-time matrix pencil method (STMPM), is introduced as an efficient approach for analyzing various scattering mechanisms in chipless RFID tags. By studying the performance of STMPM in early-time and late-time responses of the scatterers, the detection process is improved in cases of multiple tags located close to each other. A space-time-frequency algorithm is introduced based on STMPM to detect, identify, and localize multiple multi-bit chipless RFID tags in the reader area. The proposed technique has applications in electromagnetic and acoustic-based detection of targets.Ph. D.
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Dokur, Omkar. "Embedded System Design of a Real-time Parking Guidance System." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5939.
Full textAbstract:
The primary objective of this work is to design a parking guidance system to reliably detect entering/exiting vehicles to a parking garage in a cost-efficient manner. Existing solutions (inductive loops, RFID based systems, and video image processors) at shopping malls, universities, airports etc., are expensive due to high installation and maintenance costs. There is a need for a parking guidance system that is reliable, accurate, and cost-effective. The proposed parking guidance system is designed to optimize the use of parking spaces and to reduce wait times. Based on a literature review we identify that the ultrasonic sensor is suitable to detect an entering/exiting vehicle. Initial experiments were performed to test the sensor using an Arduino based embedded system. Detection logic was then developed to identify a car after analyzing the initial test results. This logic was extended to trigger a camera to take an image of the vehicle for validation purposes. This system consists of Arduino, ultrasonic sensor, and a temperature sensor. It was installed and tested in Richard Beard Garage at the University of South Florida for five days. The test results of each trial are provided and average error for all the trials is calculated. The error cases occur due to golf carts, straddling cars on both entry/exit lanes, and people walking under the sensor. The average error of the system is 5.36% over five days (120 hrs). The estimated cost for one detector per lane is approximately $30.
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Wu, Ren. "Multiple-antenna wireless communications: detection and estimation with smart antennas, and space-time code design considerations." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32616.
Full textAbstract:
The main theme of this thesis is wireless communications using multiple antennas. The thesis consists of four topics on smart antenna technology, its applications to direct sequence code division multiple access (DS/CDMA) communications, and multiple-input multiple-output wireless communications. The first problem under consideration is the joint estimation of direction-of-arrival (DoA), propagation delay, and complex channel gain for antenna-array DS/CDMA communications over frequency selective multipath channels. We propose a subspace based MUSIC-type estimation algorithm which utilizes the spatial smoothing preprocessing technique. The proposed algorithm essentially breaks the multipath induced coherency within the received signals and recovers the full signal subspace spanned by the dominant signal paths of all users. This allows for the use of MUSIC-type DoA and delay estimators for individual paths of a particular user. We then describe a new criterion for detecting the number of signals impinging on a uniform linear array (ULA), which exploits eigenvector information of the sample array covariance matrix and makes explicit use of the peak information of the MUSIC spectrum. In the third part we present an iterative weight matrix approximation (IWMA) algorithm. IWMA computes an approximation to the optimum weight matrix used by weighted spatial smoothing (WSS) to completely decorrelate input sources and generate a diagonal source covariance matrix. A useful observation regarding IWMA is that the generated matrix is suitable as a basis for subspace-type DoA estimation. In the last part we discuss two deterministic measures for designing linear processing space-timeLes communications sans fil utilisant des antennes multiples constituent le thème principal de cette thèse qui traite de quatre sujets concernant la technologie des antennes intelligentes, son application aux communications à séquence directe CDMA, et des communications à entrées multiples et sorties multiples (MIMO). Le premier sujet est celui de l'estimation simultanée des directions d'arrivée, du retard de propagation et du gain complexe du canal pour des communications CDMA sur des canaux multi-trajets à fréquences sélectives. Nous proposons un algorithme d'estimation de type MUSIC à base de sous-espaces, utilisant un prétraitement par lissage spatial. L'algorithme proposé brise essentiellement la cohérence induite par les trajets multiples pour recouvrer entièrement le sous-espace du signal créé par les signaux dominants de tous les utilisateurs. Ceci permet l'utilisation d'estimateurs MUSIC des directions d'arrivée et du retard pour les signaux d'un utilisateur donné. Nous décrivons un nouveau critère pour détecter le nombre de signaux captés sur un réseau d'antennes uniforme et linéaire qui exploite le vecteur propre de la matrice de covariance des échantillons et qui utilise l'information des pics de spectre de MUSIC. Troisièmement, nous présentons un algorithme itératif d'approximation de la matrice des poids (IWMA) qui calcule une approximation de la matrice des poids optimale utilisée pour le lissage spatial (WSS), afin de complètement décorréler les sources d'entrées. Avec IWMA la matrice qui est générée peut être utilisée comme base de l'estimation de type sous-espace des directions d'arrivée. Nous discutons finalem
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Shaw, Kwok-wah Roddy, and 邵國華. "Gay desire and the politics of space." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31953700.
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Anderson, Tiffany Christine. "Spatiality redeemed the redemption of created space in Jesus Christ and possible implications for architectural design /." Theological Research Exchange Network (TREN), 1995. http://www.tren.com.
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Héliot, F. "Design and analysis of space-time block and trellis coding schemes for single-band UWB communications systems." Thesis, King's College London (University of London), 2006. http://epubs.surrey.ac.uk/2588/.
Full textAbstract:
Ultra Wide-Band (UWB) technology has recently attracted much research interest due to its appealing features in short-range mobile communications. These features include high-data rates, low power consumption, multiple-access communications and precise positioning capabilities. Space-Time Coding (STC) techniques, such as block coding and trellis coding, are known to be simple and practical ways to increase both the spectral efficiency and the capacity in wireless communications. The the- sis aims at designing robust and efficient space-time coding schemes well adapted to single-band UWB signalling. Thus, this work incorporates a fine analysis of a stan- dard Single Input Single Output (SISO) single-band UWB system, scrutinising every important aspect of this system including transceiver structure, channel modelling, multiple-access techniques and detection process. Research also leads to the deriva- tion of a novel closed-form approximation for the average probability of bit-error for single-band UWB systems. This in-depth study highlights drawbacks inherent to UWB systems such as time-jitter effects or rake-receiver complexity and proposes schemes that benefit from spatial diversity to mitigate these problems. Thus, the thesis concentrates on the design of new multiple-antenna space-time coding systems tailored for UWB communications. As a result, this work derives and generates gen- eralised full-rate space-time block codes based on orthogonal pulses to capture both spatial and multipath diversities. Space-time trellis coded modulation is then revis- ited to further improve the spectral efficiency limit and to deliver the high-data rates promised by UWB technology. A new version of space-time trellis coding is developed for the peculiar UWB signalling structure. Finally, thanks to a novel closed-form ap- proximation, a theoretical comparison is undertaken between any SISO-UWB system and the multiple antenna UWB systems proposed in this thesis. The results clearly underline the impact of STC on a single-band UWB system in terms of enhanced robustness against timing-jitter effects, higher spectral efficiency and capacity im- provement. These advantages are finally confirmed through the numerical evaluation of the error-rate performance.
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Lee, Kuan-Yi, and 李冠儀. "Systematic Design of Space-Time Codes." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/94963496935057269977.
Full textAbstract:
碩士國立中正大學
電機工程研究所
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In this thesis, we examine the properties of modulation signal constellation and then make use of these properties. By taking advantage of the properties among the modulation points, we design the orthogonal space-time codes and the corresponding generator matrix to produce those orthogonal codes. From simulation, we discover the orthogonal space-time codes found in this thesis are the kernel of discrete time Fourier transformation. Based on the observation and signal design flow, we propose the two-stage configuration and the index matrix generator for the orthogonal space-time encoder. By this way, we can obtain the orthogonal space-time codes systematically.
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Li, Kun-Tai, and 李昆泰. "Design of Group-Theoretical Space-Time Codes." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/50410702430123994248.
Full textAbstract:
碩士國立中正大學
電機工程研究所
93
Differential transmission schemes are well tailored for unknown channels between transmitters and receivers. In a space-time coded (STC) system, the diversity product of a signal constellation and the number of matrices in the constellation will influence system performance, decoder complexity and the overall transmission rate. To achieve a low error probability at high SNR’s, the signal constellation must have full diversity and the minimum diversity product must be as large as possible. On the other hand, the encoders of group-based space-time codes share an elegant mathematical structure with a simple formula for diversity products. This thesis focuses on the encoder design of unitary space-time codes by examining space-time codes based on Cayley transform, fixed-point-free (FPF) finite groups, and special symplectic group Sp(2).
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Zhang, Qing. "Differential space-time modulation and unitary constellation design /." 2006. http://wwwlib.umi.com/dissertations/fullcit/3198421.
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Elkhazin, Akrum. "Space-time Coded Modulation Design in Slow Fading." Thesis, 2009. http://hdl.handle.net/1807/19320.
Full textAbstract:
This dissertation examines multi-antenna transceiver design over flat-fading wireless channels. Bit Interleaved Coded Modulation
(BICM) and MultiLevel Coded Modulation (MLCM) transmitter structures are considered, as well as the used of an optional spatial precoder under slow and quasi-static fading conditions. At the receiver, MultiStage Decoder (MSD) and Iterative Detection and Decoding (IDD) strategies are applied. Precoder, mapper and
subcode designs are optimized for different receiver structures over the different antenna and fading scenarios.
Under slow and quasi-static channel conditions, fade resistant multi-antenna transmission is achieved through a combination of linear spatial precoding and non-linear multi-dimensional mapping. A time-varying random unitary precoder is proposed, with significant performance gains over spatial interleaving. The fade resistant properties of multidimensional random mapping are also analyzed. For MLCM architectures, a group random labelling
strategy is proposed for large antenna systems.
The use of complexity constrained receivers in BICM and MLCM transmissions is explored. Two multi-antenna detectors are proposed based on a group detection strategy, whose complexity can be adjusted through the group size parameter. These detectors show
performance gains over the the Minimum Mean Squared Error (MMSE)detector in spatially multiplexed systems having an excess number
of transmitter antennas.
A class of irregular convolutional codes is proposed for use in BICM transmissions. An irregular convolutional code is formed by
encoding fractions of bits with different puncture patterns and mother codes of different memory. The code profile is designed with the aid of extrinsic information transfer charts, based on
the channel and mapping function characteristics. In multi-antenna
applications, these codes outperform convolutional turbo codes under independent and quasi-static fading conditions.
For finite length transmissions, MLCM-MSD performance is affected by the mapping function. Labelling schemes such as set
partitioning and multidimensional random labelling generate a large spread of subcode rates. A class of generalized Low Density
Parity Check (LDPC) codes is proposed, to improve low-rate subcode performance. For MLCM-MSD transmissions, the proposed generalized LDPC codes outperform conventional LDPC code construction over a
wide range of channels and design rates.