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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.
21

Reserch on Channel Model and Frequency Offset for MC-CDMA System

Chen, Yue-Shuan 23 June 2001 (has links)
In mobile radio systems, the bandwidth of spread spectrum signals for CDMA system is very wide. If the bandwidth exceeds the coherence bandwidth of the channel, the signal is seriously distorted by the multiple propagation paths. The available bandwidth is divided into a lot of small parts in Multi-carrier-CDMA system. Selecting the number of subcarriers according to the environment of channel will make the bandwidth of spread spectrum signals smaller than the coherence bandwidth of channel. And then the system can overcome the question of multiple propagation paths. The performance of Multi-carrier CDMA system is sensitive to frequency offset. Frequency offset results from Doppler shift due to mobile movement, as well as from a mismatch between the carrier frequency of local oscillators at the transmitter and receiver. Consequently, the subcarriers¡¦ orthogonality are lost, causing Inter-carrier Interference (ICI). The interference of other subcarriers will make the error of estimated channel coefficients. Effect of frequency offset will lower the performance of the combing detector that needing channel estimated. In this thesis, we propose a method to correct the frequency offset. Using the relation of two continuous received signals to estimate the frequency and compensate it. We will analysis and compare this method in different condition. Simulation results will demonstrate the performance of this proposed method.
22

Attentional capture by sound disappearance

Brosowsky, Nicholaus Paul 07 April 2014 (has links)
Three experiments are reported in which the attentional capture effect of sound disappearance was assessed. In all experiments participants were required to judge the pitch of target sounds that were preceded by one or more context sounds. In Experiments 1 and 2, targets presented in the same location as a context sound that had abruptly terminated 100 ms before its presentation, were identified better than target sounds presented in a different location. This result was obtained both when targets followed a single context sound (Experiment 1) and when targets followed pairs of dichotically-presented context sounds that terminated at different points (Experiment 2). The results of Experiment 3 replicated those obtained in the previous experiments and showed that under some conditions the facilitative effect could persist at intervals longer than 100 ms. The results of these experiments suggest that under some conditions, the disappearance of a sound can capture attention.
23

Fluting in heatset web offset printing process /

Nagubadi, Rajendra, January 2007 (has links) (PDF)
Thesis (M.S.) in Chemical Engineering--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 62-63).
24

Fluting in Heatset Web Offset Printing Process

Nagubadi, Rajendra January 2007 (has links) (PDF)
No description available.
25

A Bit Error Rate Analysis of Offset QPSK over the Aeronautical Telemetry Multipath Channel

Dang, Xiaoyu 10 1900 (has links)
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The impact of multipath fading parameters on the probability of error for Offset QPSK (OQPSK) is derived. The multipath fading channel is modeled using the aeronautical telemetry channel model [1-2]. Expressions for the probability of bit error are derived that are a function of the multipath model parameters. The expressions are shown to agree with computer simulations and show that a strong multipath reflection with a short delay causes much more degradation than a weak multipath reflection with a long delay.
26

OVER QUANTIZING, THE NEXT STEP IN DIGITAL SIGNAL PROCESSING

Hicks, William T. 10 1900 (has links)
International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / Simplification of the analog front end of a signal conditioning circuit can be accomplished by over-quantizing the input signal and using DSP for gain and offset. In this case, a much higher precision A/D converter is used than required by the desired output accuracy. The excess bits are then used to allow the DSP math to give an effective gain to the signal. By a similar function, offset of over 100% can be mathematically removed as long as the input signal does not exceed the A/D input voltage range.
27

TELEMETRY TRANSCEIVER DESIGN USING BOC SIGNAL

Dongkai, Yang, Li, Du, Qishan, Zhang 10 1900 (has links)
ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper focuses on the transceiver design using BOC signal in the telemetry field, including the transmitter and receiver. The transmitter is similar as that using BPSK except from the sub-carrier modulation. But the receiver design is totally different because the BOC signal has different performance. The acquisition methods of BOC signal have been discussed such as the single-side BPSK-like, double-sides BPSK-like and hybrid processing methods, which can restrain side-peak and eliminate ambiguities. The three acquisition process principles and their performances include arithmetic complexity are described, compared and simulated using MATLAB.
28

Timing and frequency synchronization for orthogonal frequency division multiple-access systems

Gul, Malik Muhammad Usman 27 August 2014 (has links)
Reliable timing and frequency synchronization is a major requirement in orthogonal frequency division multiple-access (OFDMA) systems as synchronization errors can result in inter-symbol-interference (ISI) and inter-carrier-interference (ICI) in the received signal, which severely degrade system performance. Thus, the objective of the proposed research is to develop, analyze, and prototype timing and frequency synchronization techniques for downlink (DL) and uplink (UL) OFDMA transmissions. For synchronization in DL OFDMA transmissions, we have developed conditions to select appropriate Zadoff-Chu sequences as training symbols that allow timing synchronization in the presence of large carrier frequency offsets (CFO). Using the proposed training block, we have designed training signal detection, timing synchronization, and integer CFO estimation algorithms. We have further proposed the training signal design for frequency synchronization in DL coordinated multi-point (COMP) transmissions, in which a user has to synchronize to multiple base-stations at the same time. In this respect, a frequency synchronization algorithm for DL COMP receiver has been designed using the proposed training signal along with its hardware implementation to analyze real-time performance. For frequency synchronization in UL OFDMA transmissions, we have proposed a null sub-carrier-based CFO estimation algorithm, and carried out its identifiability and acquisition range analysis. The proposed algorithm supports both sub-band and generalized sub-carrier allocations. We have also designed a CFO estimation and compensation algorithm for UL single-carrier frequency division multiple-access (SC-FDMA) transmissions. The proposed algorithm is based on parallel factor analysis and supports interleaved sub-carrier allocation. In addition, it guarantees the identifiability of CFO estimation and allows the system to operate on full load. Detailed simulations results have been provided along with discussions on computational requirements, which reveal that the proposed algorithms provide significant improvements in performance and efficiency compared to state of the art schemes in the literature.
29

Estimation of Steering Wheel Angle in Heavy-Duty Trucks

Fejes, Peter January 2016 (has links)
The project presented in this report is a master's thesis performed at Scania CV. The main purpose is to develop an algorithm that estimates the offset of the values that the steering wheel angle sensor reports in a truck or tractor, and also to investigate the possibility to estimate the steering wheel angle in real-time. The developed algorithm successfully estimates the offset to an accuracy on the order of degrees, and the uncertainty of the estimate is ultimately determined by the backlash in the steering system, which may range up to approximately 15 degrees or more depending on service standards. The investigation also shows that two general approaches to estimate the steering wheel angle in real-time can produce unbiased estimates only when the vehicle is cornering at low speeds.
30

Análise da compensação por perda de biodiversidade no setor de mineração de calcário. / Biodiversity offset in quarrying sector.

Souza, Barbara Almeida 20 September 2017 (has links)
Em resposta à crescente perda de biodiversidade, diversos países adotam políticas de compensação que buscam equilibrar a destruição do habitat local restaurando, aprimorando e / ou protegendo áreas. Tais mecanismos são cada vez mais importantes no setor de mineração, onde a perda de habitat pode ser inevitável devido à rigidez locacional dos recursos minerais e com a coincidência com as áreas de importância da biodiversidade. Buscando contribuir para o avanço da compreensão da prática atual de compensação por perda de biodiversidade, investigamos as práticas adotadas em três minerações de calcário, em conformidade com a Lei da Mata Atlântica, lei federal que visa proteger este hotspot. Foram adotados os mecanismos de proteção e restauração em razões de área de 1: 1 a 1: 5. As principais dificuldades relatadas pelos atores chave foi encontrar áreas adequadas, métodos para calcular perdas residuais e incertezas sobre o sucesso da restauração. As melhores práticas recomendadas internacionalmente são parcialmente seguidas, com maior aderência observada para o caso cuja avaliação de impacto ambiental foi mais detalhada e forneceu uma base mais forte para planejar a compensação. Os resultados sugerem que a qualidade do planejamento e implementação de compensações está diretamente relacionada à qualidade da avaliação de impacto ambiental e, portanto, do licenciamento ambiental. / In response to the increasing loss of biodiversity, several countries have adopted offsetting policies that seek to balance local habitat destruction by restoring, enhancing and/or protecting equivalent values offsite. Such mechanisms are increasingly important in quarrying, where habitat loss may be unavoidable due to colocation of mineral resources and areas of biodiversity importance. Seeking to contribute to advance understanding of the current practice of biodiversity offsetting, we investigated actions required for environmental approval of three limestone quarries in compliance with Brazil\'s Atlantic Forest Act, a federal law that aims at protecting this biodiversity hotspot. Both protection and restoration offsets were applied at area ratios from 1:1.1 to 1:5. The main difficulties reported by practitioners are to find suitable areas, methods to calculate residual losses and uncertainties about the success of restoration. Internationally recommended best practices are partially followed with the highest adherence observed for the case whose environmental impact statement was more detailed and provided a stronger basis for designing the offset. Results suggest that the quality of offset planning and implementation is directly related to the quality of the environmental impact assessment.

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