• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 166
  • 26
  • 18
  • 5
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 265
  • 265
  • 66
  • 40
  • 39
  • 31
  • 30
  • 24
  • 22
  • 21
  • 20
  • 18
  • 18
  • 17
  • 17
  • 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

Nonparameter density estimation and its application in communication theory

Wright, George Alfred, Jr. 05 1900 (has links)
No description available.
22

Matched-field source detection and localization in high noise environments a novel reduced-rank signal processing approach.

Riley, H. Bryan. January 1994 (has links)
Thesis (Ph. D.)--Ohio University, March, 1994. / Title from PDF t.p.
23

The perceived urgency and detection time of multi-tone and frequency-modulated warning signals in broadband noise /

Haas, Ellen Carla, January 1993 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 174-193). Also available via the Internet.
24

Fast optical signal detected in the prefrontal lobe with near-infrared spectroscopy during sleep

Zhao, Jun, January 2005 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 11, 2007) Includes bibliographical references.
25

Signal detection in unknown interference channels /

Li, Tao. January 2006 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 124-133). Also available in electronic version.
26

Fuzzy classification of biomedical signals

楊永生, Yang, Yongsheng. January 1996 (has links)
published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy
27

Coil array optimization and wireless transceiver design for MRI

Wei, Juan, 魏娟 January 2007 (has links)
published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
28

Pulsed laser ablation of piezoelectric materials.

January 1993 (has links)
by Fei Yang. / Title also in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 92-96). / ACKNOWLEDGEMENTS --- p.i / ABSTRACT --- p.ii / TABLE OF CONTENT --- p.iii / Chapter CHAPTER I. --- INTRODUCTION --- p.1 / Chapter §1.1 --- The Background of Pulsed Laser Ablation --- p.1 / Chapter §1.2 --- Properties of PZT --- p.3 / Chapter §1.3 --- Objectives of This Thesis --- p.7 / Chapter CHAPTER II. --- INTERACTION OF PULSED LASER RADIATION WITH A SOLID TARGET --- p.8 / Chapter §2.1 --- Introduction --- p.8 / Chapter §2.2 --- Absorption of Laser Radiation by the Target --- p.9 / Chapter §2.3 --- Absorption of Laser Radiation by the Plume --- p.11 / Chapter §2.4 --- Ablation Depth and Ablation Rate --- p.12 / Chapter §2.5 --- Formation and Evolution of the Plume --- p.14 / Chapter (a) --- Small-time Solution (c´Øt ζ) --- p.15 / Chapter (b) --- Large-time Solution (c´Øt ζ) --- p.15 / Chapter §2.6 --- Piezoelectric Signal --- p.17 / Chapter §2.7 --- Angular Distributions --- p.21 / Chapter §2.8 --- Target Surface Temperature --- p.26 / Chapter CHAPTER III. --- EXPERIMENTAL TECHNIQUES --- p.27 / Chapter §3.1 --- Pulsed Laser System --- p.27 / Chapter §3.2 --- Setup for Piezoelectric Detection of Laser Pulse --- p.28 / Chapter §3.3 --- Setup for Optical Measurement of Laser Plasma --- p.30 / Chapter §3.4 --- Setup for Ion Detection --- p.32 / Chapter §3.5 --- Sample Preparation --- p.35 / Chapter CHAPTER IV. --- PIEZOELECTRIC DETECTION OF LASER ABLATION --- p.38 / Chapter §4.1 --- Laser Ablation of a Piezoelectric Target --- p.38 / Chapter §4.1.1 --- Pyroelectric Effect --- p.38 / Chapter §4.1.2 --- Laser-induced Piezoelectric Signal (LIPS) --- p.39 / Chapter §4.2 --- Propagation of LIPS --- p.41 / Chapter §4.3 --- Laser Ablation Threshold --- p.45 / Chapter §4.4 --- Ablation Rate Measurement by LIPS --- p.47 / Chapter §4.5 --- Temperature Dependence of LIPS --- p.53 / Chapter §4.5.1 --- The Polarization Measurement --- p.53 / Chapter §4.5.2 --- The Piezoelectric Coefficient --- p.56 / Chapter CHAPTER V. --- STUDIES OF LASER PLASMA BY FARADAY PROBE METHOD --- p.59 / Chapter §5.1 --- Angular Distribution of The Plume Density --- p.59 / Chapter §5.2 --- The Plume Ionization Fraction --- p.64 / Chapter §5.3 --- The Plume Velocity Distribution and The Plume Temperature --- p.72 / Chapter §5.4 --- The Target Surface Temperature --- p.82 / Chapter §5.5 --- Plume Orientation Determination --- p.85 / Chapter CHAPTER VI. --- OVERALL CONCLUSION --- p.90 / REFERENCES --- p.92
29

Studies of Extensions of HRM-SDT for Constructed Responses

Zhou, Xiaoliang January 2019 (has links)
This research examines an ordered perception rater model, an extension of the equal perception signal detection theory (SDT) latent class rater model. The expectation-maximization algorithm and the Newton-Raphson algorithm are used to estimate parameters. Four simulation studies are conducted to answer three research questions. Simulation studies 1 and 2 fit correct models to the data. Simulation study 1 generates one hundred data sets from the equal perception rater model, both with fully-crossed design and BIB design, and both without and with rater effects, and fits the equal perception model. Parameter recovery is excellent for fully-crossed design and reasonable for BIB design, and all rater effects are detected. Simulation study 2 generates one hundred simulated data sets from the ordered perception model, both with fully-crossed design and BIB design, and both without and with rater effects, and fits the ordered perception rater model. Although parameter recovery is biased for some parameters in the BIB design, all rater effects are recovered. Simulation studies 3 and 4 fit wrong models to the data. Simulation study 3 fits equal perception models to the fully-crossed and BIB ordered perception data sets generated in simulation study 2. All rater effects are revealed, although rater effects are distorted to some extent in the BIB design. Simulation study 4 fits ordered perception models to the fully-crossed and BIB equal perception data sets generated in study 1. All rater effects are recovered. Using essay scores from a large-scale language test, an empirical study is conducted. Both the equal and the ordered perception models are fitted. Information criteria favor the equal perception model.
30

Advanced precoding and detection techniques for large MIMO systems.

January 2014 (has links)
多輸入多輸出傳輸在過去二十多年來無線通信研究中一直處於中心地位。人們對信息需求的爆炸性增長導致大規模多輸入多輸出系統的出現與發展。在大規模多輸入多輸出系統中有幾十甚至上百的天線與用戶。這種大規模天線能夠極大地提高系統容量及對噪聲的魯棒性。然而,大規模天線系統的物理實現卻是十分困難的。一方面,最優的信號處理算法通常需要指數增長的複雜度。另一方面,數目繁多的天線意味大量包括功率放大器和數模轉換器在內的硬件開銷。這篇論文的研究重點在於能夠降低信號處理複雜度和硬件開銷的信號檢測和預編碼算法。具體而言,本論文的研究包括三部分: / 在第一部分中,我們考慮多輸入多輸出系統中的一個基本問題信號檢測。格型解碼是信號檢測中的一種傳統方法。但是格型解碼(以及其快速近似算法格基規約輔助算法)放鬆了信號檢測中的符號邊界約束因而受到性能限制。我們提出一種自適應的正則化方法來避免格型解碼中邊界約束鬆弛帶來的負面影響。這種方法是基於最大似然解碼器的拉格朗日對偶鬆弛。我們發現了格型解碼和最大似然解碼的一個十分有趣的關係,而這個關係在現有的文獻中並沒有被提及。數值仿真結果顯示拉格朗日對偶鬆弛方法比現有的格型解碼更為優勝。 / 在第二部分中,我們考慮多用戶信號廣播中的矢量擾動方法。矢量擾動是一種能夠接近信道總容量以及簡化用戶數據處理方法。然而,傳統的矢量擾動會導致每根傳輸天線上都有相當大的功率, 導致天線模擬前端的硬件實現有相當大的難度。我們提出一種每天線功率受限的矢量擾動方法來解決這個問題。在這個方法中,我們需要解決一個整數規劃問題。然而,求解這個整數規劃問題需要用到複雜度十分高的枚舉算法。我們用拉格朗日對偶鬆弛方法把這個整數規劃轉化為標準的整數最小二乘問題,然後採用快速的近似算法來求解。數值仿真顯示提出的方法能夠顯著地降低高每天線功率造成的功率回饋。 / 在最後一部分,我們考慮單用戶通信中的恆定包絡預編碼。恆定包絡預編碼是一種最近被提出用於超大規模多輸入多輸出系統的方法。恆定包絡預編碼的優點在於能夠利用價格低廉但是功率效率高的功率放大器。但是恆定包絡預編碼中的一些信號處理問題在之前的文獻中只是得到了部分解答。我們為這些信號處理問題提供了一個完整的解決方案。更進一步地,我們用天線子集選擇來加強恆定包絡預編碼以優化天線傳輸信號及進一步降低天線成本。數值仿真結果顯示包絡預編碼的性能只稍遜於傳統的波束成型方法,但是能恆定包絡傳輸和降低活動的天線數目。 / Multiple-input multiple-output (MIMO) transmission has been at the core of wireless communication research for the past two decades. Driven by the explosive increase of data demand, the development of MIMO systems has entered a large-scale realm where there are dozens of or even more than a hundred antennas and users. The large number of antennas can significantly boost the system throughput and robustness against noise. However, the physical realization of such a large MIMO system can be very complicated and expensive. On the one hand, optimal signal processing algorithms usually have complexities that increase rapidly in the numbers of antennas and users. On the other hand, large number of antennas means increased hardware overheads, such as those of power amplifiers and D/A converters. This thesis considers efficient precoding and detection algorithms that can reduce implementation complexity and cost. Specifically, the thesis consists of the following three parts: / In the first part, we consider a fundamental problem in MIMO communication, namely MIMO detection. The traditional lattice decoding methods, as well as its efficient approximations by lattice reduction aided (LRA) methods, relax the symbol bounds in detection and thus suffer from performance loss. We propose a systematic adaptive regularization approach to lattice decoding to alleviate the adverse effect of symbol bound relaxation, which is based on the study of a Lagrangian dual relaxation (LDR) of the optimal maximum-likelihood (ML) detector. We find an intriguing relationship between lattice decoding and ML, which was not reported in the previous literature. Simulation results show that the proposed LDR approach can significantly outperform existing lattice decoding and LRA methods. / In the second part, we consider the vector perturbation approach which is a promising technique to achieve near-sum capacity and allows simple user processing in the multiuser multiple-input single-output (MISO) downlink scenario. However, the conventional vector perturbation designs can have very high perantenna powers, which causes significant difficulty to power amplifier implementations. To tackle this problem, we propose a vector perturbation design with per-antenna power constraints (VP-PAPC). The resulting optimization problem is an integer program which requires a computationally demanding enumeration process. Lagrangian dual relaxation is used to transform the VP-PAPC problem into standard integer least square problems which may have efficient approximations. Simulation results show that the proposed method can effectively reduce the power back-off caused by high per-antenna power in conventional vector perturbation. / In the last part, we consider constant envelope (CE) precoding in the singleuser MISO downlink scenario. CE precoding is recently proposed as a mean to utilize cheap but power-efficient power amplifiers in very large MIMO systems. We provide complete solutions to some fundamental signal processing issues in CE precoding which were only partially solved in the previous literature. In addition, we enhance CE precoding with antenna subset selection for transmit optimization and implementation cost reduction. Simulation results reveal that the proposed method only exhibits moderate power loss compared to non-CE beamforming but have the advantages of CE transmission and fewer active transmitting antennas. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Pan, Jiaxian. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 135-147). / Abstracts also in Chinese.

Page generated in 0.1129 seconds