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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Examining Machine Learning as an alternative for scalable video analysis / En utvärdering av maskininlärning som alternativ för skalbar videoanalys

Ragnar, Niclas, Tolic, Zoran January 2019 (has links)
Video is a large part of today’s society where surveillance cameras represent the biggest source of big data, and real-time entertainment is the largest network traffic category. There is currently a large interest in analysing the contents of video where video analysis is mainly conducted by people. This increase in video has for instance made it difficult for professional editors to analyse movies and series in a scalable way, and alternative solutions are needed. The media technology company June, want to explore scalable alternatives for extracting metadata from video. With recent advances in Machine Learning and the rise of machine-learning-asa-service platforms, June wished more specifically to explore how these Machine Learning services can be utilised for extracting metadata from videos, and from it construct a summary regarding its contents. This work examined Machine Learning as an option for scalable video summarisation which resulted in developing and evaluating an application that utilised transcription, summarisation, and translation services to produce a text based summarisation of video. Furthermore to examine the services current state of affairs, multiple services from different providers were tested, evaluated and compared to each other. Lastly, in order to evaluate the summarisation services an evaluation model was developed. The test results showed that the translation services were the only service that produced good results. Transcription and summarisation performed poorly in the tests which renders the suggested solution of combining the three services for video summarisation as impractical. / Video är en stor del av dagens samhälle där bland annat övervakningskameror är den största källan av data och underhållning i realtid är den kategori som står för mest nätverkstrafik. Det finns i dagsläget ett stort intresse i att analysera innehållet av video, denna videoanalys utförs även främst av människor. Ökningen av video har gjort det svårt för exempelvis professionella redaktörer att hinna analysera filmer och serier och mer skalbara alternativ behövs. Mediaföretaget June vill utforska alternativ för att extrahera metadata från video på ett skalbart sätt. Med de senaste framstegen inom maskininlärning och framväxten av machine-learningas-a-service plattformar, önskar June mer specifikt att utforska hur maskininlärning kan nyttjas för att extrahera metadata från video och med det konstruera en sammanfattning av innehållet. Det utförda arbetet undersökte maskininlärning som skalbart alternativ för att kunna sammanfatta videos innehåll. Arbetet resulterade i utvecklandet samt utvärderingen av en applikation som nyttjade maskininlärningstjänster för transkribering, sammanfattning samt översättning för att producera en textbaserad sammanfattning av videos innehåll. För att utvärdera tjänsternas nuvarande tillstånd så testades samt utvärderades tjänster från olika leverantörer för att sedan jämföras mot varandra. Slutligen framtogs en egenutvecklad modell för att kunna utvärdera tjänsterna för sammanfattning. Testresultaten visade att tjänsterna för översättning var de enda tjänsterna som gav bra resultat. Tjänsterna för transkribering och sammanfattning gav dåliga resultat vilket gör den föreslagna lösningen av att kombinera de tre tjänsterna för att sammanfatta videoinnehåll som opraktisk.
82

SOME PRACTICAL CONSIDERATIONS IN THE USE OF PSEUDO-RANDOM SEQUENCES FOR TESTING THE EOS AM-1 RECEIVER

O’Donnell, John 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / There are well-known advantages in using pseudo-random sequences for testing of data communication links. The sequences, also called pseudo-noise (PN) sequences, approximate random data very well, especially for sequences thousands of bits long. They are easy to generate and are widely used for bit error rate testing because it is easy to synchronize a slave pattern generator to a received PN stream for bit-by-bit comparison. There are other aspects of PN sequences, however, that are not as widely known or applied. This paper points out how some of the less familiar characteristics of PN sequences can be put to practical use in the design of a Digital Test Set and other specialbuilt test equipment used for checkout of the EOS AM-1 Space Data Receiver. The paper also shows how knowledge of these PN sequence characteristics can simplify troubleshooting the digital sections in the Space Data Receiver. Finally, the paper addresses the sufficiency of PN data testing in characterizing the performance of a receiver/data recovery system.
83

BANDWIDTH EFFICIENCY AND BER PERFORMANCE OF ENHANCED AND FEC CODED FQPSK

Lin, Jinsong, Feher, Kamilo 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Bit error rate (BER) and bandwidth efficiency of several variations of enhanced Feher patented quadrature phase shift keying (FQPSK) [1] are described. An enhanced FQPSK increases the channel packing density of that of the IRIG 106-00 standardized FQPSK-B by approximately 50% in adjacent channel interference (ACI) environment. As the bandwidth efficiency of FQPSK-B DOUBLES (2×) that of pulse code modulation/Frequency modulation (PCM/FM) [5], the enhanced FQPSK, with a simpler transceiver than FQPSK-B, has a channel packing density of TRIPLE (3×) that of PCM/FM. One of the other enhanced FQPSK prototypes has an end to end system loss of only 0.4 dB at BER=1x10^(-3) and 0.5 dB at BER=1x10^(-4) from ideal linearly amplified QPSK theory. The enhanced FQPSK has a simple architecture, thus is inexpensive and has small size, for ultra high bit rate implementation. With low redundancy forward error correction (FEC) coding which expands the spectrum by approximately 10%, further improvement of about 3-4.5dB E N b o is attained with NLA FQPSK-B and enhanced FQPSK at BER=1x10^(-5) .
84

Simulation and analytic evaluation of false alarm probability of a non-linear detector

Amirichimeh, Reza, 1958- January 1991 (has links)
One would like to evaluate and compare complex digital communication systems based upon their overall bit error rate. Unfortunately, analytical expressions for bit error rate for even simple communication systems are notoriously difficult to evaluate accurately. Therefore, communication engineers often resort to simulation techniques to evaluate these error probabilities. In this thesis importance sampling techniques (variations of standard Monte Carlo methods) are studied in relation to both linear and non-linear detectors. Quick simulation, an importance sampling method based upon the asymptotics of the error estimator, is studied in detail. The simulated error probabilities are compared to values obtained by numerically inverting Laplace Transform expressions for these quantities.
85

Quaternary CLB a falul tolerant quaternary FPGA

Rhod, Eduardo Luis January 2012 (has links)
A diminuição no tamanho dos transistores vem aumentando cada vez mais o número de funções que os dispositivos eletrônicos podem realizar. Apesar da diminuição do tamanho mínimo dos transistores, a velocidade máxima dos circuitos não consegue seguir a mesma taxa de aumento. Um dos grandes culpados apontados pelos pesquisadores são as interconexões entre os transistores e também entre os componentes. O aumento no número de interconexões dos circuitos traz consigo um significativo aumento do cosumo de energia, aumento do atraso de propagação dos sinais, além de um aumento da complexidade e custo do projeto dos circuitos integrados. Como uma possível solução a este problema é proposta a utilização de lógica multivalorada, mais especificamente, a lógica quaternária. Os dispositivos FPGAs são caracterizados principalmente pela grande flexibilidade que oferecem aos projetistas de sistemas digitais. Entretanto, com o avanço nas tecnologias de fabricação de circuitos integrados e diminuição das dimensões de fabricação, os problemas relacionados ao grande número de interconexões são uma preocupação para as próximas tecnologias de FPGAs. As tecnologias menores que 90nm possuem um grande aumento na taxa de erros dos circuitos, na lógica combinacional e sequencial. Apesar de algumas potenciais soluções começara a ser investigadas pela comunidade, a busca por circuitos tolerantes a erros induzidos por radiação, sem penalidades no desempenho, área ou potência, ainda é um assunto de pesquisa em aberto. Este trabalho propõe o uso de circuitos quaternários com modificações para tolerar falhas provenientes de eventos transientes. Como principal contribuição deste trabalho destaca-se o desenvolvimento de uma CLB (do inglês Configurable Logic Block) quaternária capaz de suportar eventos transientes e, na possibilidade de um erro, evitá-lo ou corrigi-lo. / The decrease in transistor size is increasing the number of functions that can be performed by the electronic devices. Despite this reduction in the transistors minimum size, the circuit’s speed does not follow the same rate. One of the major reasons pointed out by researchers are the interconnections between the transistors and between the components. The increase in the number of circuit interconnections brings a significant increase in energy consumption, propagation delay of signals, and an increase in the complexity and cost of new technologies IC designs. As a possible solution to this problem the use of multivalued logic is being proposed, more specifically, the quaternary logic. FPGA devices are characterized mainly by offering greater flexibility to designers of digital systems. However, with the advance in IC manufacturing technologies and the reduced size of the minimum fabricated dimensions, the problems related to the large number of interconnections are a concern for future technologies of FPGAs. The sub 90nm technologies have a large increase in the error rate of its functions for the combinational and sequential logic. Although potential solutions are being investigated by the community, the search for circuits tolerant to radiation induced errors, without performance, area, or power penalties, is still an open research issue. This work proposes the use of quaternary circuits with modifications to tolerate faults from transient events. The main contribution of this work is the development of a quaternary CLB (Configurable Logic Block) able to withstand transient events and the occurrence of soft errors.
86

Characterization and evaluation of ZigBee modules

Ramazanali, Hawar January 2006 (has links)
<p>This thesis work started with an extensive literature study in several areas, ZigBee, instruments and measuring methods. The knowledge was implemented in use with the ZigBee modules from the two manufacturers ITN and Chipcon along with ZigBee Software Stack. Measuring methods were developed and software in ZigBee software Stack was developed to use in the ZigBee modules for the measurements. Developing measurement methods and performing measurements was an iterative process for the different measurements. The aim was to characterize the ZigBee modules in the most important areas during the extent of this master thesis work.</p>
87

Transparent Satellite Switching using Flexible Frequency-band Reallocation

Yagüe, Edgar Cámara, Carretero, José Manuel Menéndez January 2006 (has links)
<p>The society expects a global interconected digital communication system offering multimedia services, information on demand and interchange of information with a high data rates and low cost. </p><p>All this can not be realized with the terrestrial nets used nowadays cause it is necessary a high economic inversion to get a competitive capacity to interchange information between server and user. The next generation of satellite must have characteristics which improve the current generation, one important requirement is that the same satellite could make a treatment of the different input signals. With this we can avoid a spent of lots of money and time because we do not need terrestrial stations which modify the signals before the information is sent to the satellite.</p><p>For all this, we need an on board treatment of the information in the satellite. We design a frequency bank reallocation (FBR) network by using a filter bank system. This is the first step of the thesis. After we get FBR we introduce some different input signals and analyze the output, using parameters like symbol error rate and variance.</p><p>One important part in the thesis is the QAM signals used to test our system. For this, we design a modulator and a demodulator of QAM4, 16 and 64, paying more attention in the QAM64, cause is the modulation where more errors can appear due to we have got more possible chances which means more precision in the recovery of the signal.</p>
88

Transparent Satellite Switching using Flexible Frequency-band Reallocation

Yagüe, Edgar Cámara, Carretero, José Manuel Menéndez January 2006 (has links)
The society expects a global interconected digital communication system offering multimedia services, information on demand and interchange of information with a high data rates and low cost. All this can not be realized with the terrestrial nets used nowadays cause it is necessary a high economic inversion to get a competitive capacity to interchange information between server and user. The next generation of satellite must have characteristics which improve the current generation, one important requirement is that the same satellite could make a treatment of the different input signals. With this we can avoid a spent of lots of money and time because we do not need terrestrial stations which modify the signals before the information is sent to the satellite. For all this, we need an on board treatment of the information in the satellite. We design a frequency bank reallocation (FBR) network by using a filter bank system. This is the first step of the thesis. After we get FBR we introduce some different input signals and analyze the output, using parameters like symbol error rate and variance. One important part in the thesis is the QAM signals used to test our system. For this, we design a modulator and a demodulator of QAM4, 16 and 64, paying more attention in the QAM64, cause is the modulation where more errors can appear due to we have got more possible chances which means more precision in the recovery of the signal.
89

Characterization and evaluation of ZigBee modules

Ramazanali, Hawar January 2006 (has links)
This thesis work started with an extensive literature study in several areas, ZigBee, instruments and measuring methods. The knowledge was implemented in use with the ZigBee modules from the two manufacturers ITN and Chipcon along with ZigBee Software Stack. Measuring methods were developed and software in ZigBee software Stack was developed to use in the ZigBee modules for the measurements. Developing measurement methods and performing measurements was an iterative process for the different measurements. The aim was to characterize the ZigBee modules in the most important areas during the extent of this master thesis work.
90

A Novel Precoding Scheme for Systems Using Data-Dependent Superimposed Training

Chen, Yu-chih 31 July 2012 (has links)
For channel estimation without data-induced interference in data-dependent superimposed training (DDST) scheme, the data sequence is shifted by subtracting a data-dependent sequence before added to training sequence at transmitter. The distorted term causes the data identification problem (DIP) at the receiver. In this thesis, we propose two precoding schemes based on previous work. To maintain low peak-to-average power ratio (PAPR), the precoding matrix is restricted to a diagonal matrix. The first scheme is proposed to enlarge the minimum distance between the closest codewords, termed as efficient diagonal scheme. Conditions to make sure the precoding matrix is efficient for M-ary phase shift keying (MPSK) and M-ary quadrature amplitude modulation (MQAM) modulation are listed in this paper. The second scheme pursues a lowest complexity at receiver which means the amount of searching set is reduced. It is a trade-off between the better bit error rate (BER) performance and a lower complexity at receiver. The simulation results show that PAPR have been improved and the DIP is solved in both schemes.

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