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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.
51

Novel algorithms in wireless CDMA systems for estimation and kernel based equalization

Vlachos, Dimitrios January 2012 (has links)
A powerful technique is presented for joint blind channel estimation and carrier offset method for code- division multiple access (CDMA) communication systems. The new technique combines singular value decomposition (SVD) analysis with carrier offset parameter. Current blind methods sustain a high computational complexity as they require the computation of a large SVD twice, and they are sensitive to accurate knowledge of the noise subspace rank. The proposed method overcomes both problems by computing the SVD only once. Extensive simulations using MatLab demonstrate the robustness of the proposed scheme and its performance is comparable to other existing SVD techniques with significant lower computational as much as 70% cost because it does not require knowledge of the rank of the noise sub-space. Also a kernel based equalization for CDMA communication systems is proposed, designed and simulated using MatLab. The proposed method in CDMA systems overcomes all other methods.
52

ANALYTICAL AND EXPERIMENTAL CHARACTERIZATION OF SOQPSK AND MULTI-H CPM IN A MULTIPATH CHANNEL

Hill, Terrance J. 10 1900 (has links)
International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Shaped Offset QPSK (SOQPSK) has been shown to be nearly identical in performance to Feher-patented FQPSK, which is the Advanced Range Telemetry (ATRM) program's Tier I waveform. Multi-h CPM has been selected as the ARTM Tier II waveform, because it offers 50% better spectral efficiency than the Tier I waveform. Both the Tier I and Tier II waveforms must operate in a multipath channel in order to meet the range community's telemetry requirements. This paper presents an analytical and experimental characterization of SOQPSK and Multi-h CPM in the presence of multipath. Quantitative results are presented which demonstrate the relative robustness of the ARTM Tier I and Tier II waveforms, in channels representative of a typical range environment.
53

AN ENHANCED, CONSTANT ENVELOPE, INTEROPERABLE SHAPED OFFSET QPSK (SOQPSK) WAVEFORM FOR IMPROVED SPECTRAL EFFICIENCY

Hill, Terrance J. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Shaped BPSK (SBPSK) and Shaped Offset QPSK (SOQPSK), as defined in various MIL standards, are widely employed on SATCOM links because they offer an attractive combination of good spectral efficiency, constant envelope characteristics, and interoperability with legacy equipments. More recently, numerous terrestrial applications of OQPSK and similar waveforms (Feher-patented FQPSK) have been proposed. The present paper describes a simple non-proprietary modification of the MIL-STD SOQPSK waveform which offers spectral containment and detection efficiency comparable to or better than FQPSK-B (Revision A1), while preserving a constant envelope characteristic and backward compatibility with existing equipment.
54

Applications of impedance-based fault locating methods in power systems

Min, Kyung Woo 18 September 2014 (has links)
The concentration of this work is in estimating fault locations in power systems. After describing the basic concepts of fault locating methods, this work describes improving the fault location estimates, applying the fault locating methods, and implementing the methods in a software. Every work described in the Chapter will be evaluated whether by actual field data or simulated data based on field parameters. / text
55

Ink film splitting acoustics and tack on paper in offset printing

Voltaire, Joakim January 2004 (has links)
<p>This licentiate thesis comprises two complementary studiesdealing with the sheet-fed offset printing of paper. The firststudy addresses the further development of a practical methodto acoustically monitor and analyse the film splitting ofoffset inks. This method was tested on laboratory printingequipment, specifically monitoring the continuous ink splittingin the nip of an IGT ink distribution unit and the short-timeink splitting in the inked print disc-paper nip of the printingunit of an ISIT instrument. The study verified that the inksplitting component of the acoustic signal contributes to thehigher frequency range (10-20 kHz) of the audible spectrum, andcan thus be separated from the lower frequency machine noise.Furthermore, the film splitting component is sensitive tochanges in the ink and printing conditions, thus enabling itsuse in probing the fundamental mechanisms occurring during inktransfer and also suggesting its applicability fornon-intrusive monitoring of industrial printing presses. Anincrease in film thickness during ink distribution correspondsto an increased acoustic power, with the exception of very lowink amounts, which give reduced acoustic emission due to alubricating effect. The effect of the presence of fountainsolution was simulated by adding emulsion-forming, butnon-evaporative, ethylene glycol. This produces an increase inacoustic power at low amounts, due to resistance to glycol dropdeformation, followed by a decrease at higher amounts owing toexcess glycol lining the rolls. During test printing on paper,increasing ink amounts also display an increased acousticresponse.</p><p>The second study further developed a theoretical model toexplain and predict the evolution of ink tack in terms of inksetting directly after offset printing on coated paper. Asmeasured by the ISIT, the tack of the printed ink rises duringshorter time periods, attains a maximum, and then falls atlonger times. The proposed model described how the ink tack,characterised by the impulse during disc pull-off, dependsdynamically on the viscoelastic properties of the ink, thecontact with paper and disc, and the flow geometry. The inksetting was modelled as a diffusion-limited transport of theoil vehicle through the ink film and into the pores of thecoated paper. The coupling of the tack and setting models,compared to the ISIT experimental measurements, then provided adiffusion coeffcient for ink setting during the tack riseperiod. This coeffcient decreases with time, and increasinglyrapidly with decreasing ink amounts due to theconcentration-dependent diffusion. For an accurate descriptionthe elasticity and adhesion effects also have to be considered,at least for explaining the tack fall period.</p>
56

The Impact of a Primary Care Psychology Training Program on Medical Utilization in a Community Sample

Lanoye, Autumn 01 January 2014 (has links)
Mental illness and psychological distress is associated with higher rates of medical service usage and treatment of these issues results in more appropriate medical utilization rates. Little research has been conducted in an integrated care clinic, wherein health psychologists or behavioral health specialists work together with physicians to provide patient care. The current study examines the effects of brief behavioral and mental health interventions on patient medical utilization in this setting with care delivered by medical residents and doctoral psychology trainees. Access to the health system’s electronic billing records allowed for objective measures of annual healthcare utilization in terms of inpatient, outpatient, and emergency department use. A quasi-control group was constructed using propensity score matching in order to compare patients who had received a primary care psychology intervention to those who had not. Rates of inpatient utilization decreased significantly among treated patients overall as well as among treated patients identified as frequent attenders; there was no change in inpatient utilization among patients in the control group overall nor among frequent attenders in the control group, indicating that there is likely an effect of behavioral and mental health treatment on rates of inpatient visits. Rates of emergency department use and specialty outpatient visits were comparable between treated and control group patients, suggesting the lack of a treatment effect in these areas. Strengths, limitations, possible mechanisms, and implications for future research are discussed.
57

A compensação ambiental e os instrumentos da Política Nacional de Meio Ambiente

Giasson, Moara Menta 12 1900 (has links)
Submitted by FERNANDA DA SILVA VON PORSTER (fdsvporster@univates.br) on 2016-09-27T18:37:05Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2015MoaraMentaGiasson.pdf: 1049549 bytes, checksum: 138fa368551e11afcbab2608a74b071b (MD5) / Approved for entry into archive by Ana Paula Lisboa Monteiro (monteiro@univates.br) on 2016-09-29T18:32:10Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2015MoaraMentaGiasson.pdf: 1049549 bytes, checksum: 138fa368551e11afcbab2608a74b071b (MD5) / Made available in DSpace on 2016-09-29T18:32:10Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2015MoaraMentaGiasson.pdf: 1049549 bytes, checksum: 138fa368551e11afcbab2608a74b071b (MD5) Previous issue date: 2016-09 / As preocupações com a degradação ambiental cada vez mais visível em meados do século XX mobilizaram as Conferências da Organização das Nações Unidas (ONU) sobre meio ambiente em Estocolmo (1972) e no Rio de Janeiro (1992). Esse movimento deu origem às políticas ambientais no Brasil, marcadas pelas concepções de meio ambiente da época. A Política Nacional do Meio Ambiente, de 1981, cria instrumentos para compatibilizar o desenvolvimento econômico-social com a preservação da qualidade ambiental e do equilíbrio ecológico. O controle de empreendimentos poluidores é feito por meio do licenciamento e da avaliação de impactos ambientais. Já a criação de espaços territoriais especialmente protegidos é uma ferramenta da Política para a conservação da biodiversidade. No Brasil, estes instrumentos embasam a compensação ambiental, a qual garante recursos de empreendimentos licenciados para criação e manutenção de unidades de conservação. Internacionalmente, o objetivo da compensação é alcançar a equivalência entre perdas e ganhos em termos de biodiversidade, de forma mensurável. Nesta dissertação é investigada a possibilidade da compensação ambiental no Brasil ser considerada um mecanismo gerador de ganho ambiental ou que garanta, minimamente, não haver perda de biodiversidade na implantação de projetos licenciados. Os estudos de caso evidenciaram que o procedimento de licenciamento não aponta claramente a conexão entre os impactos identificados nos estudos ambientais, e as medidas de mitigação e compensação executadas. As compensações, no entanto, revelaram que há equivalência ecológica entre a área impactada e as unidades de conservação beneficiadas. Conclui-se que a ferramenta de compensação ambiental brasileira apresenta potencial de contribuição para a perda zero de biodiversidade nos empreendimentos licenciados, sendo necessária a adequação no procedimento de licenciamento para a utilização da hierarquia de mitigação, e a exigência de medidas compensatórias que sejam mensuráveis e que garantam a equivalência ecológica entre as áreas impactadas e protegidas. / Worries about the ever more visible environmental degradation in the mid-twentieth century ignited the United Nations’ (UN) Conferences on the Environment in Stockholm (1972) and in Rio de Janeiro (1992). This movement originated environmental policies in Brazil, marked by the period’s understanding of environment. The 1981 National Environmental Policy creates instruments to reconcile social-economic development and preserving environmental quality and ecologic balance. Polluting enterprises are controlled through licensing and the environmental impact assessment. The creation of protected areas is tool in the policy for biodiversity conservation. In Brazil, these instruments are the foundation of environmental compensation (offset), which guarantees resources from licensed enterprises to create and maintain conservation units. Internationally, the goal of offset is to reach the equivalency between gains and losses in terms of biodiversity in a measurable way. In this dissertation, the possibility of environmental compensation in Brazil being considered a mechanism to generate environmental gain and to guarantee, at a minimum, no loss of biodiversity in the establishment of licensed projects is investigated. Case studies show that the licensing procedure has no clear connection between impacts identified by environmental studies and executed mitigation and compensation measures. Compensations, nevertheless, reveal that there is ecologic equivalency between the impacted area and the benefited conservation units. In conclusion, Brazil’s environmental compensation tool presents the potential to contribute to zero net loss of biodiversity in licensed enterprises. However, it is necessary to adjust the licensing procedure in order to use mitigation hierarchy, and the requirement of measurable compensatory ecologic equivalency measures.
58

Os contratos de offset como instrumento da política pública de inovação: estudo sobre a efetividade das compensações tecnológicas no setor de defesa

Álvares, João Gabriel January 2016 (has links)
Submitted by Fernanda Weschenfelder (fernanda.weschenfelder@uniceub.br) on 2018-06-11T19:37:55Z No. of bitstreams: 1 61400186.pdf: 1981131 bytes, checksum: 0bbd150df7b7568d9cc07d76356ec261 (MD5) / Approved for entry into archive by Fernanda Weschenfelder (fernanda.weschenfelder@uniceub.br) on 2018-06-11T19:38:02Z (GMT) No. of bitstreams: 1 61400186.pdf: 1981131 bytes, checksum: 0bbd150df7b7568d9cc07d76356ec261 (MD5) / Made available in DSpace on 2018-06-11T19:38:02Z (GMT). No. of bitstreams: 1 61400186.pdf: 1981131 bytes, checksum: 0bbd150df7b7568d9cc07d76356ec261 (MD5) Previous issue date: 2016 / O tema do presente trabalho são os contratos de compensação, mais especificamente, aqueles que incluem transferência de tecnologia. Os contratos de offset foram analisados consoante sua instrumentalidade e procedimentalidade. O estudo teve como foco o setor de defesa brasileiro em virtude da experiência adquirida por este setor no emprego do instituto contratual das compensações. Partiu-se das seguintes indagações: de que maneira as compras públicas no setor de defesa podem contribuir com o desenvolvimento tecnológico nacional? E ainda: quais fatores impactam a efetividade das compensações tecnológicas? Realizou-se inicialmente pesquisa bibliográfica e documental. Na sequência, realizou-se pesquisa empírica, cujos instrumentos de coleta de dados utilizados foram o painel de especialistas e o questionário on-line. Identificou-se que há grande interação entre o setor de defesa e a inovação tecnológica, e que as compras públicas de defesa podem estimular o desenvolvimento tecnológico a partir de acordos de compensação tecnológica. Outrossim, os órgãos integrantes da defesa já dispõem de estrutura capaz de apoiar o desenvolvimento tecnológico nacional e balizam seus projetos e setores estratégicos por tecnologias inovadoras. No que tange às espécies compensatórias, identificou-se que os offsets tecnológicos são os que possibilitam benefícios mais expressivos para o caso brasileiro, dado o hiato tecnológico que separa o país dos Estado desenvolvidos. Dada a complexidade das compensações tecnológicas, foram identificados doze critérios para avaliação das propostas de offsets tecnológicos, divididos em noventa e seis subcritérios. A partir do processo analítico hierárquico, os critérios e subcritérios foram submetidos ao painel de especialistas. Obteve-se como resultado uma matriz de avaliação de propostas de compensações tecnológicas, a qual contém o valor percentual correspondente à contribuição de cada subcritério para a meta institucional de promover o desenvolvimento tecnológico nacional. Realizou-se estudo de caso do projeto piloto do Sistema Integrado de Monitoramento de Fronteiras (SISFRON), que é um projeto estratégico do Exército Brasileiro. A matriz de avaliação foi validada a partir da sua aplicação às propostas das compensações tecnológicas em execução no referido projeto, obtendo-se um valor numérico para cada proposta, possibilitando priorizar as propostas com base em dados objetivos. A partir das respostas ao questionário on-line, constatou-se que os fiscais dos contratos de compensação tecnológica têm baixo grau de concordância com o painel de especialistas, o que indica que o processo de avaliação de propostas de compensação tecnológica depende de um conjunto de expertises que incluem conhecimentos jurídicos, técnicos e gerenciais. Concluiu-se que as compensações tecnológicas resultantes de compras públicas em defesa podem contribuir com a política pública de inovação desde que esta seja ampla o suficiente para abarcar a defesa e outras áreas de atuação estatal.
59

Using the Offset Panel Technique to Develop Innovative Origami-Based Applications

Morgan, Michael Robert 01 June 2015 (has links)
Origami, the art of folding paper, was once only an art form. In recent years, it has collided with the world of engineering and is acting as a source of inspiration for solutions to various engineering problems. Paper, the typical material used in the art form, is thin and works well for origami, but is not often suitable for use in engineering. Researchers have developed a handful of methods for accommodating thick/rigid materials in origami design. Most of these preserve only the kinematics of the model or its range of motion. Not only does the offset panel technique (OPT) preserve both the kinematics and the range of motion, it also allows for flexibility in design. This work focuses on the further development of the OPT and its potential to be implemented in real-world applications. The OPT provides design flexibility by allowing for the use of various and multiple materials, the modification of panel geometry, and the utilization of any rigid-foldable origami pattern. These and other capabilities are demonstrated in several application examples.
60

Contributions to Frequency Offset and Time Delay Estimation

Olsson, Mattias January 2006 (has links)
<p>The demand for reliable high rate and efficient communication is ever increasing. In this thesis we look at two different problems in such systems, and their possible solutions.</p><p>In recent years orthogonal frequency division multiplexing (OFDM) has gone from a promising data transmission technique to become a mainstream technique used in several current and future standards. The main attractive property of OFDM is that it is inherently resilient to multipath reflections because of its long symbol time. However, this comes at the cost of a relatively high sensitivity to carrier frequency offsets (CFOs).</p><p>In this thesis we present a technique for CFO estimation in OFDM systems that is based on locating the spectral minimas within so-called null or virtual subcarriers embedded in the spectrum.~The spectral minimas are found iteratively over a number of symbols and is therefore mainly useful for frequency offset tracking or in systems where an estimate is not immediately required, such as in TV or radio broadcasting systems. However, complexity wise the estimator is relatively easy to implement and it does not need any extra redundancy beside a nonmodulated subcarrier. The estimator performance is studied both in a channel with additive white Gaussian noise and in a frequency selective channel environment.</p><p>A goal for many years has been to be able to implement as much as possible of a radio system in the digital domain, the ultimate goal being so called software defined radio (SDR). One important part of an SDR receiver is the high speed analog-to-digital converter(ADC) and one path to reach this goal is to use a number of parallel, time-interleaved, ADCs. Such ADCs are, however, sensitive to sampling instant offsets, DC offset and gain offset.</p><p>This thesis also discusses iterative time-delay estimators (TDEs) utilizing adjustable fractional-delay filters. The TDEs could for example be used to estimate and calibrate the relative delay between the ADCs comprising the time interleaved ADC. TDEs using a direct correlator and an average squared difference function are compared. Furthermore, an analysis of the effects of the batch length dependence is presented.</p> / Report code: LiU-Tek-Lic-2006:33.

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