Tesis sobre el tema "Signal efficiency"
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Berndsen, Kevin J. "Signal Optimization for Efficient High-Power Amplifier Operation". University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307985518.
Texto completoAlonso, Kevin. "A high efficiency method for exploiting an ultra fast opto-electric signal generator". FIU Digital Commons, 1999. http://digitalcommons.fiu.edu/etd/1109.
Texto completoPan, Lu. "Coding and Signal Processing Techniques for High Efficiency Data Storage and Transmission Systems". Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293753.
Texto completoGonzalez, Maria C. y George R. Branner. "EFFECTS OF NON- LINEAR AMPLIFICATION ON N-GMSK AND N-FQPSK SIGNAL STATISTICS". International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/605306.
Texto completoDigital modulation schemes that are power and bandwidth efficient are highly desirable. After non-linear amplification has been done, signal modulation schemes having constant or quasi-constant envelopes are not as susceptible to spectral regrowth as those with non-constant envelopes. Since such distortion generates interference in the adjacent channels, the power operation of the amplifier in non-constant envelope modulations is typically backed off, resulting in systems with reduced power efficiency. On the other hand, constant envelope modulation may have different bandwidth spectra. This paper examines the statistical characteristics of N-GMSK and N-FQPSK [1] signals to assess the bandwidth efficiency in the presence of amplifier nonlinearities.
Schmitz, Michael J. "Multisine Excitation Design to Increase the Efficiency of System Identification Signal Generation and Analysis". Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26701.
Texto completoQian, Hua. "Power Efficiency Improvements for Wireless Transmissions". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/11649.
Texto completoFlanagan, T. B. "Signal controlled roundabouts : An investigation into the efficiency of signal controlled roundabouts utilizing simulation techniques with particular reference to junctions with three approaches". Thesis, University of Bradford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376678.
Texto completoDeshpande, Vinit Vinod. "Evaluating the Impacts of Transit Signal Priority Strategies on Traffic Flow Characteristics:Case Study along U.S.1, Fairfax County, Virginia". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31319.
Texto completoMaster of Science
Kamdar, Vaibhavi Killol. "Evaluating the Transit Signal Priority Impacts along the U.S. 1 Corridor in Northern Verginia". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/30845.
Texto completoMaster of Science
Mallavarpu, Navin. "Large signal model development and high efficiency power amplifier design in cmos technology for millimeter-wave applications". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44711.
Texto completoNetzer, Gilbert. "Efficient LU Factorization for Texas Instruments Keystone Architecture Digital Signal Processors". Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170445.
Texto completoEnergiförbrukningen av storskaliga högpresterande datorsystem (HPC) har blivit ett av de främsta problemen för såväl ägare av dessa system som datortillverkare. Det har lett till ett förnyat intresse för alternativa datorarkitekturer som kan vara betydligt mer effektiva ur energiförbrukningssynpunkt. För detaljerade analyser av prestanda och energiförbrukning av dessa för HPC-industrin nya arkitekturer krävs väloptimerade implementationer av standard HPC-bänkmärkningsproblem. Syftet med detta examensarbete är att tillhandhålla ett sådant högkvalitativt verktyg i form av en implementation av ett bänkmärkesprogram för LU-faktorisering för den åttakärniga digitala signalprocessorn (DSP) TMS320C6678 från Texas Instruments. Bänkmärkningsproblemet är samma som för det inom HPC-industrin välkända bänkmärket “high-performance LINPACK” (HPL). Den här presenterade implementationen nådde upp till en prestanda av 30,9 GF/s vid 1,25 GHz klockfrekvens genom att samtidigt använda alla åtta kärnor i DSP:n. Detta motsvarar 77% av den teoretiskt uppnåbara prestandan, vilket är jämförbart med förväntningar på effektivteten av mer traditionella x86-baserade system. En detaljerad prestandaanalys visar att detta tillstor del uppnås genom den högoptimerade implementationen av den ingående matris-matris-multiplikationen. Användandet av specialiserade “direct memory access” (DMA) hårdvaruenheter för kopieringen av data mellan det externa DDR3 minnet och det interna kärn-privata och delade arbetsminnet tillät att överlappa dessa operationer med beräkningar. Optimerade mjukvaruimplementationer av dessa beräkningar, delvis utförda i maskinspåk, tillät att utföra matris-multiplikationen med upp till 95% av den teoretiskt nåbara prestandan. I rapporten ges en detaljerad beskrivning av dessa två nyckeltekniker. Energiförbrukningen vid exekvering av det implementerade bänkmärket kunde med hjälp av en för ändamålet anpassad Advantech TMDXEVM6678L evalueringsmodul bestämmas till maximalt 2,92 GF/J. Resultat från verifikationen av bänkmärkesimplementationen och en uppskattning av mätosäkerheten vid de experimentella mätningarna presenteras också.
Chen, Xiaohui. "Bahadur Efficiencies for Statistics of Truncated P-value Combination Methods". Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/1238.
Texto completoAbdelghaffar, Hossam Mohamed Abdelwahed. "Developing and Testing a Novel De-centralized Cycle-free Game Theoretic Traffic Signal Controller: A Traffic Efficiency and Environmental Perspective". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/100681.
Texto completoPHD
Holmström, Johnny. "GOVERNOR ELECTRONICS FOR DIESEL ENGINES : High availability platform for real-time control and advanced fuel efficiency algorithms". Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-20282.
Texto completoFossila bränslen är en dyrbar råvara och förbränningen av detta bränsle leder till negativa miljöeffekter. Detta papper utvärderar och verifierar elektroniken som behövs för att beräkna intelligenta algoritmer som minskar bränsle konsumtionen för kommersiella fartyg. Detta görs genom att sammanfoga avancerade funktioner i en och samma elektroniska enhet som kontrollerar bränsle insprutningen på stora diesel motorer, denna elektronik är känd som en varvtals regulator. Kontroll systemet är klassificerat som ett säkerhetskritiskt system. Detta betyder att elektroniken måste utformas för att vara felsäker. För att tillåta framtida forskning och utveckling behöver plattformen vara flexibel. Den ska tillåta konfiguration av hårdvara och mjukvara ändringar. Samverkan mellan hårdvara och mjukvara. För effektiv installation samt drifttagning, måste systemet vara automat-kalibrerande och utrustat med programmerbara byglingar som möjliggör en kostnadseffektiv lösning. Beräkningen av bränsle optimeringen behöver en detaljerad modell av fartygets rörelse. Detta möjliggörs genom att integrera moderna sensorer och en mängd olika kommunikationsmedier. Bland annat så utvärderades gyroskop kontra accelerometrar för att hitta den bästa lösningen i förhållande till kostnad och kvalitet. Denna design ersätter den nuvarande produkten DEGO III. Den nya produkten behöver samma funktionalitet samt en mängd nya funktioner. Fokus har varit kommunikation, metoder för att samla sensordata och ökad beräknings kraft. När en ny generation av en produkt ska utvecklas finns uppgifter så som att välja komponenter, frågor gällande mönsterkorts layout och en utvärdering av leverantörs källor. Tillverkningen av prototypen inkluderar utvärdering av produktions metoder för att effektivisera tillverkning och verifiering.
Jang, Haedong. "NONLINEAR EMBEDDING FOR HIGH EFFICIENCY RF POWER AMPLIFIER DESIGN AND APPLICATION TO GENERALIZED ASYMMETRIC DOHERTY AMPLIFIERS". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406269587.
Texto completoSamy, Md Arif Abdulla. "Characterization of 3D Silicon Pixel Detectors for the ATLAS ITk". Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/347623.
Texto completoSchindler, Stefan [Verfasser]. "An improved signal model for a dual-phase xenon TPC using Bayesian inference and studies on the software trigger efficiency of the XENON1T DAQ system / Stefan Schindler". Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2021. http://d-nb.info/1227048599/34.
Texto completoJirattigalachote, Amornrat. "Provisioning Strategies for Transparent Optical Networks Considering Transmission Quality, Security, and Energy Efficiency". Doctoral thesis, KTH, Optical Network Laboratory (ON Lab), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94011.
Texto completoQC 20120508
Shehata, Mohamed. "Hybrid Analogue and digital techniques applied to massive MIMO systems for 5G transmission at millimeter waves". Thesis, Rennes, INSA, 2019. http://www.theses.fr/2019ISAR0026.
Texto completoThe main aim of this work is to analytically analyze the performance of Hybrid Beamforming (HBF) in Millimeter Wave (mmWave) massive Multiple Input Multiple Output (MIMO) systems, to develop low complexity HBF algorithms to adapt with such systems and finally to verify the practical validity of these algorithms. The massive MIMO antenna array provides high transmit gain overcoming the severe path-loss limitation of the mm Wave systems. On the other had applying HBF in sparse channels achieves close Spectral Efficiency (SE) perfonnance compared to the full digital beamforming, however with lower hardware cost and power consumption. In this thesis we start by defining the conditions for which bath the HBF and full digital beamfonning can achieve exactly similar SE performance. Then, we analyze the SE perfonnance gap that arise between them in sparse mmWave MIMO channels. Moreover, we provide closed form SE models for basic analog and HBF techniques in typical mmWave MIMO channels. Later we consider a Multi User (MU) massive MIMO HBF framework that considers multiple spatial signal processing techniques for the analog domain processing, digital domain processing, power allocation and users scheduling. We develop low complexity algorithms for such framework in order to provide a low complexity practical HBF framework for future wireless communication networks that can cope with the challenges of mm Wave channels
Anany, Hossam. "Effectiveness of a Speed Advisory Traffic Signal System for Conventional and Automated vehicles in a Smart City". Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-156650.
Texto completoRukpakavong, Wilawan. "Energy-efficient and lifetime aware routing in WSNs". Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14497.
Texto completoShibata, Takafumi, Masaaki Katayama y Akira Ogawa. "Performance of Asynchronous Band-Limited DS/SSMA Systems". IEICE, 1993. http://hdl.handle.net/2237/7200.
Texto completoChataut, Robin. "Optimization of Massive MIMO Systems for 5G Networks". Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1707262/.
Texto completoDallmeyer, Matthew John. "Reducing Fir Filter Costs: A Review of Approaches as Applied to Massive Fir Filter Arrays". University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417544448.
Texto completoKandukuri, Somasekhar Reddy. "Spatio-Temporal Adaptive Sampling Techniques for Energy Conservation in Wireless Sensor Networks". Thesis, La Réunion, 2016. http://www.theses.fr/2016LARE0021/document.
Texto completoWireless sensor networks (WSNs) technology have been demonstrated to be a usefulmeasurement system for numerous bath indoor and outdoor applications. There is avast amount of applications that are operating with WSN technology, such asenvironmental monitoring, for forest fire detection, weather forecasting, water supplies, etc. The independence nature of WSNs from the existing infrastructure. Virtually, the WSNs can be deployed in any sort of location, and provide the sensor samples accordingly in bath time and space. On the contrast, the manual deployments can only be achievable at a high cost-effective nature and involve significant work. ln real-world applications, the operation of wireless sensor networks can only be maintained, if certain challenges are overcome. The lifetime limitation of the distributed sensor nodes is amongst these challenges, in order to achieve the energy optimization. The propositions to the solution of these challenges have been an objective of this thesis. ln summary, the contributions which have been presented in this thesis, address the system lifetime, exploitation of redundant and correlated data messages, and then the sensor node in terms of usability. The considerations have led to the simple data redundancy and correlated algorithms based on hierarchical based clustering, yet efficient to tolerate bath the spatio-temporal redundancies and their correlations. Furthermore, a multihop sensor network for the implementation of propositions with more features, bath the analytical proofs and at the software level, have been proposed
Desmond, Allan Peter. "An analytical signal transform derived from the Walsh Transform for efficient detection of dual tone multiple frequency (DTMF) signals". Thesis, Bucks New University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401474.
Texto completoChiu, Leung Kin. "Efficient audio signal processing for embedded systems". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44775.
Texto completoBenjebbour, Anass. "Efficient Signal Processing Techniques for MIMO Systems". 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147580.
Texto completoZaidi, Syed Izhar Hussain. "Power Efficient Signal Processing in Reconf0igurable Computing". Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520204.
Texto completoHwang, Suk-seung, John J. Shynk y Hua Lee. "Efficient AOA Estimation Techniques for GPS Signal". International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596458.
Texto completoGlobal Positioning System (GPS) interference signals are suppressed using angle-of-arrival (AOA) techniques, while at the same time the power of the GPS signal is enhanced. After estimating all AOAs from the received signal, we must determine which AOA corresponds to the GPS signal of interest, and in the presence of high-power interference signals. In this paper, we describe an algorithm for selecting the GPS AOA by first comparing all AOAs derived from the received signals before despreading. Although this approach has excellent performance, it has a high computational complexity. In order to overcome this drawback, we introduce a modification that yields an efficient GPS AOA estimation algorithm, which is based on a modified despreader and the constant modulus (CM) array cost function. The CM array is capable of selecting signals that have a constant modulus while rejecting non-CM interference signals. The modified despreader is the mechanism that allows this to be achieved, where unlike the interference signals, the GPS signal of interest maintains a constant modulus.
Gouba, Oussoulare. "Approche conjointe de la réduction du facteur de crête et de la linéarisation dans le contexte OFDM". Phd thesis, Supélec, 2013. http://tel.archives-ouvertes.fr/tel-00931304.
Texto completoWeaver, Ben. "Computationally-efficient Signal Processing Algorithms for Communications Systems". Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503326.
Texto completoHolm, Rasmus. "Energy-Efficient Mobile Communication with Cached Signal Maps". Thesis, Linköpings universitet, Programvara och system, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-124607.
Texto completoBrandon, Mathilde. "Optimisation conjointe de méthodes de linéarisation de l'émetteur pour des modulations multi-porteuses". Phd thesis, Université de Cergy Pontoise, 2012. http://tel.archives-ouvertes.fr/tel-00762747.
Texto completoManda, Manoj Sai. "Communication Channel Analysis for Efficient Beamforming". Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-20776.
Texto completoKawala-Janik, Aleksandra. "Efficiency evaluation of external environments control using bio-signals". Thesis, University of Greenwich, 2013. http://gala.gre.ac.uk/9810/.
Texto completoShoji, Seiichiro. "Efficient individualisation of binaural audio signals". Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442378.
Texto completoCui, Xian. "Efficient radio frequency power amplifiers for wireless communications". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195652135.
Texto completoAsai, Takahiro. "Spatiotemporal signal processing for highly-efficient broadband wireless communications". 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136019.
Texto completoVariyam, Pramodchandran. "Efficient testing techniques for analog and mixed-signal circuits". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13457.
Texto completoFisher, Andrew N. "Efficient, sound formal verification for analog/mixed-signal circuits". Thesis, The University of Utah, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10003590.
Texto completoThe increasing demand for smaller, more efficient circuits has created a need for both digital and analog designs to scale down. Digital technologies have been successful in meeting this challenge, but analog circuits have lagged behind due to smaller transistor sizes having a disproportionate negative affect. Since many applications require small, low-power analog circuits, the trend has been to take advantage of digital's ability to scale by replacing as much of the analog circuitry as possible with digital counterparts. The results are known as \emph{digitally-intensive analog/mixed-signal} (AMS) circuits. Though such circuits have helped the scaling problem, they have further complicated verification. This dissertation improves on techniques for AMS property specifications, as well as, develops sound, efficient extensions to formal AMS verification methods. With the \emph{language for analog/mixed-signal properties} (LAMP), one has a simple intuitive language for specifying AMS properties. LAMP provides a more procedural method for describing properties that is more straightforward than temporal logic-like languages. However, LAMP is still a nascent language and is limited in the types of properties it is capable of describing. This dissertation extends LAMP by adding statements to ignore transient periods and be able to reset the property check when the environment conditions change. After specifying a property, one needs to verify that the circuit satisfies the property. An efficient method for formally verifying AMS circuits is to use the restricted polyhedral class of \emph{zones}. Zones have simple operations for exploring the reachable state space, but they are only applicable to circuit models that utilize constant rates. To extend zones to more general models, this dissertation provides the theory and implementation needed to soundly handle models with ranges of rates. As a second improvement to the state representation, this dissertation describes how octagons can be adapted to model checking AMS circuit models. Though zones have efficient algorithms, it comes at a cost of over-approximating the reachable state space. Octagons have similarly efficient algorithms while adding additional flexibility to reduce the necessary over-approximations. Finally, the full methodology described in this dissertation is demonstrated on two examples. The first example is a switched capacitor integrator that has been studied in the context of transforming the original formal model to use only single rate assignments. Th property of not saturating is written in LAMP, the circuit is learned, and the property is checked against a faulty and correct circuit. In addition, it is shown that the zone extension, and its implementation with octagons, recovers all previous conclusions with the switched capacitor integrator without the need to translate the model. In particular, the method applies generally to all the models produced and does not require the soundness check needed by the translational approach to accept positive verification results. As a second example, the full tool flow is demonstrated on a digital C-element that is driven by a pair of RC networks, creating an AMS circuit. The RC networks are chosen so that the inputs to the C-element are ordered. LAMP is used to codify this behavior and it is verified that the input signals change in the correct order for the provided SPICE simulation traces.
Maraš, Mirjana. "Learning efficient signal representation in sparse spike-coding networks". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEE023.
Texto completoThe complexity of sensory input is paralleled by the complexity of its representation in the neural activity of biological systems. Starting from the hypothesis that biological networks are tuned to achieve maximal efficiency and robustness, we investigate how efficient representation can be accomplished in networks with experimentally observed local connection probabilities and synaptic dynamics. We develop a Lasso regularized local synaptic rule, which optimizes the number and efficacy of recurrent connections. The connections that impact the efficiency the least are pruned, and the strength of the remaining ones is optimized for efficient signal representation. Our theory predicts that the local connection probability determines the trade-off between the number of population spikes and the number of recurrent synapses, which are developed and maintained in the network. The more sparsely connected networks represent signals with higher firing rates than those with denser connectivity. The variability of observed connection probabilities in biological networks could then be seen as a consequence of this trade-off, and related to different operating conditions of the circuits. The learned recurrent connections are structured, with most connections being reciprocal. The dimensionality of the recurrent weights can be inferred from the network’s connection probability and the dimensionality of the feedforward input. The optimal connectivity of a network with synaptic delays is somewhere at an intermediate level, neither too sparse nor too dense. Furthermore, when we add another biological constraint, adaptive regulation of firing rates, our learning rule leads to an experimentally observed scaling of the recurrent weights. Our work supports the notion that biological micro-circuits are highly organized and principled. A detailed examination of the local circuit organization can help us uncover the finer aspects of the principles which govern sensory representation
Heyne, Benjamin. "Efficient CORDIC based implementation of selected signal processing algorithms". Aachen Shaker, 2008. http://d-nb.info/991790073/04.
Texto completoYatawatta, Sarod Petropulu Athina P. "Efficient signal processing techniques for future wireless communications systems /". Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/374.
Texto completoGalluzzo, Francesca <1985>. "Efficient ultrasonic signal processing techniques for aided medical diagnostics". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5731/1/galluzzo_francesca_tesi.pdf.
Texto completoL’ecografia è una tecnica diagnostica per immagini utilizzata nella pratica clinica, non invasiva, poco costosa e in tempo reale. La bassa qualità delle immagini rende l’interpretazione complessa e soggettiva. Per supportare i medici nella diagnosi è possibile utilizzare sistemi Computer Aided Detection (CAD). La tesi discute tecniche efficienti di elaborazione dei segnali ultrasonici per diagnostica medica supportata da computer. Vengono trattate due tematiche: (i) la caratterizzazione tissutale basata su ultrasuoni, finalizzata al miglioramento del protocollo bioptico per la diagnosi del tumore alla prostata; (ii) la segmentazione di immagini ecocardiografiche, finalizzata all’individuazione dei contorni delle strutture cardiache per misurare in modo automatico le dimensioni dell’organo e calcolare indici di funzionalità clinicamente rilevanti. Nell’ambito del primo tema è stato sviluppato un sistema CAD. I contributi in quest’ambito sono: (i) lo sviluppo di un robusto sistema di classificazione, (i) l’utilizzo di elaborazione parallela su GPU per ottenere prestazioni in tempo reale; (iii) l’introduzione di un nuovo algoritmo di apprendimento semi-supervisionato e di una procedura di addestramento capace di utilizzare tutti i dati raccolti. Il sistema guida il medico indirizzando il campionamento bioptico verso zone potenzialmente patologiche. Una validazione con dati clinici ha dimostrato la validità del sistema come strumento di supporto alla diagnosi in grado di consentire una riduzione del numero di campioni necessari per una diagnosi accurata. Nell’ambito del secondo tema è stato sviluppato uno strumento per la diagnosi dei malfunzionamenti cardiaci tramite ecocardiografia 3D real-time. I contributi della tesi sono: (i) lo sviluppo di un framework di segmentazione automatica per immagini 3D basato sulla tecnica level-set e operante su GPU; (ii) la sua applicazione ad immagini ecocardiografiche tridimensionali. Risultati sperimentali ne hanno dimostrato l’elevata efficienza e flessibilità. Una validazione su dati clinici ne ha dimostrato l’efficacia come strumento di supporto al medico per l’analisi quantitativa della morfologia e della funzionalità cardiaca.
Galluzzo, Francesca <1985>. "Efficient ultrasonic signal processing techniques for aided medical diagnostics". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5731/.
Texto completoL’ecografia è una tecnica diagnostica per immagini utilizzata nella pratica clinica, non invasiva, poco costosa e in tempo reale. La bassa qualità delle immagini rende l’interpretazione complessa e soggettiva. Per supportare i medici nella diagnosi è possibile utilizzare sistemi Computer Aided Detection (CAD). La tesi discute tecniche efficienti di elaborazione dei segnali ultrasonici per diagnostica medica supportata da computer. Vengono trattate due tematiche: (i) la caratterizzazione tissutale basata su ultrasuoni, finalizzata al miglioramento del protocollo bioptico per la diagnosi del tumore alla prostata; (ii) la segmentazione di immagini ecocardiografiche, finalizzata all’individuazione dei contorni delle strutture cardiache per misurare in modo automatico le dimensioni dell’organo e calcolare indici di funzionalità clinicamente rilevanti. Nell’ambito del primo tema è stato sviluppato un sistema CAD. I contributi in quest’ambito sono: (i) lo sviluppo di un robusto sistema di classificazione, (i) l’utilizzo di elaborazione parallela su GPU per ottenere prestazioni in tempo reale; (iii) l’introduzione di un nuovo algoritmo di apprendimento semi-supervisionato e di una procedura di addestramento capace di utilizzare tutti i dati raccolti. Il sistema guida il medico indirizzando il campionamento bioptico verso zone potenzialmente patologiche. Una validazione con dati clinici ha dimostrato la validità del sistema come strumento di supporto alla diagnosi in grado di consentire una riduzione del numero di campioni necessari per una diagnosi accurata. Nell’ambito del secondo tema è stato sviluppato uno strumento per la diagnosi dei malfunzionamenti cardiaci tramite ecocardiografia 3D real-time. I contributi della tesi sono: (i) lo sviluppo di un framework di segmentazione automatica per immagini 3D basato sulla tecnica level-set e operante su GPU; (ii) la sua applicazione ad immagini ecocardiografiche tridimensionali. Risultati sperimentali ne hanno dimostrato l’elevata efficienza e flessibilità. Una validazione su dati clinici ne ha dimostrato l’efficacia come strumento di supporto al medico per l’analisi quantitativa della morfologia e della funzionalità cardiaca.
Tervo, O. (Oskari). "Transceiver optimization for energy-efficient multiantenna cellular networks". Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526219356.
Texto completoTiivistelmä Tämä väitöskirja keskittyy ajankohtaiseen energiatehokkaaseen lähetinsuunnitteluun langattomissa solukkoverkoissa, joissa suorituskykymittarina käytetään energiatehokkuuden (energy efficiency (EE)) maksimointia, eli kuinka monta bittiä pystytään lähettämään yhtä energiayksikköä kohti. Työn painopiste on lähettimien keilanmuodostuksen (beamforming (BF)) ja aktiivisten lähetinantennien optimoinnissa. EE-optimoinnin uutuusarvo on ottaa lähettimien prosessoinnin tehonkulutus huomioon keilanmuodostuksen suunnittelussa, varsinaisen lähetystehon lisäksi. Työ antaa hyvän käsityksen erityisesti tämänhetkisten solukkoverkkojen energiatehokkuudesta, ja luo työkaluja EE-optimointiin tulevaisuuden järjestelmissä. Ensin suunnitellaan keilanmuodostus yksisolumallissa, jossa tehonkulutus kasvaa lähetystehon ja aktiivisten radiotaajuusketjujen lukumäärän mukana. Ongelmaan johdetaan optimaalinen ratkaisu, ja kaksi käytännöllistä menetelmää perustuen nollaanpakotukseen tai peräkkäinen konveksi approksimaatio (successive convex approximation (SCA)) -ideaan. Seuraavaksi keskitytään keilanmuodostuksen ja antenninvalinnan yhteisoptimointiin (joint beamforming and antenna selection (JBAS)), jossa radiotaajuusketjuja voidaan sulkea EE:n parantamiseksi. Tähän ehdotetaan optimaalinen menetelmä ja kaksi käytännöllistä SCA-menetelmää perustuen binääristen ja jatkuvien muuttujien yhteisoptimointiongelman relaksaatioon, tai harvan vektorin optimointiin. Monisoluverkon EE-optimoinnissa käytetään yksityiskohtaisempaa tehonkulutusmallia, joka skaalautuu myös datanopeuden ja prosessoinnin monimutkaisuuden mukaan. Työssä käytetään kahta suorituskyvyn mittaria: 1) koko verkon energiatehokkuuden, ja 2) painotettujen energiatehokkuuksien summien maksimointia (weighted sum EEmax (WsumEEmax)). Ensin johdetaan keskitetyt ratkaisut SCA-ideaa käyttäen. Tämän jälkeen keskitytään hajautettuun optimointiin, joka pystytään toteuttamaan paikallisen kanavatiedon avulla, kun matalanopeuksinen skalaariarvojen jako on käytettävissä tukiasemien välillä. Ensin WsumEEmax-ongelma ratkaistaan yhdistämällä SCA ja kerrointen vaihtelevan suunnan menetelmä, ja lisäksi ehdotetaan iteratiivinen suljetun muodon ratkaisu molempiin ongelmiin, joka mahdollistaa tarkan laskennallisen monimutkaisuuden määrityksen. Lopussa työ laajennetaan monisoluverkkoon, jossa tukiasemat palvelevat käyttäjäryhmiä ryhmälähetyksenä. Keskittymällä JBAS-ongelmaan, ensin ehdotetaan lähestymistapa parantaa SCA-menetelmän suorituskykyä yhteisoptimointiongelman relaksaation ratkaisemisessa. Toinen yksinkertaisempi lähestymistapa perustuu harvan vektorin optimointiin, joka ei vaadi binäärisiä muuttujia. Lisäksi menetelmiä muunnellaan myös energiatehokkuuden ja summadatanopeuden kompromissin optimointiin. Lopussa työ ottaa huomioon vielä moniantennivastaanottimet, joka mahdollistaa sekä täsmälähetyksen että ryhmälähetyksen samanaikaisesti. Menetelmien suorituskykyä arvioidaan laajamittaisilla tietokonesimulaatioilla. Tulokset näyttävät väitöskirjan menetelmien lisäävän energiatehokkuutta 30-300% verrattuna lukuisiin perinteisiin menetelmiin BF-optimoinnissa, ja JBAS-menetelmät antavat vielä yli 100% lisää suorituskykyä
Nordlund, Per-Johan. "Efficient Estimation and Detection Methods for Airborne Applications". Doctoral thesis, Linköpings universitet, Institutionen för systemteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15826.
Texto completoMahdi, Abdul-Hussain Ebrahim. "Efficient generalized transform algorithms for digital implementation". Thesis, Bangor University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277612.
Texto completoTurnes, Christopher Kowalczyk. "Efficient solutions to Toeplitz-structured linear systems for signal processing". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51878.
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