• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 684
  • 252
  • 79
  • 57
  • 42
  • 37
  • 30
  • 26
  • 25
  • 14
  • 9
  • 8
  • 7
  • 7
  • 7
  • Tagged with
  • 1505
  • 1031
  • 249
  • 238
  • 223
  • 215
  • 195
  • 185
  • 167
  • 163
  • 151
  • 124
  • 123
  • 122
  • 111
  • 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.
121

Fully modified least squares estimation and vector autoregression of models with seasonally integrated processes.

January 1997 (has links)
by Gilbert Chiu-sing Lui. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 112-117). / Chapter 1. --- Introduction --- p.1 / Chapter 2. --- Models and Assumptions --- p.4 / Chapter 3. --- Asymptotics of FM-SEA Estimators --- p.15 / Chapter 3.1. --- Model without Determinstic Trends --- p.15 / Chapter 3.2. --- Model with Determinstic Trends --- p.27 / Chapter 4. --- Asymptotics of FM-SEA Estimators of VAR System --- p.33 / Chapter 4.1. --- General Model --- p.33 / Chapter 4.2. --- Model with d = 4 --- p.44 / Chapter 5. --- Monte Carlo Experimental Results --- p.49 / Chapter 6. --- Conclusion --- p.54 / Chapter 7. --- Mathematical Appendix --- p.56 / Chapter 8. --- References --- p.112
122

Sensor network deployment as least squares problems.

January 2011 (has links)
Xu, Yang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 99-104). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background of Sensors and Sensor Networks --- p.2 / Chapter 1.2 --- Introduction to Coverage Problems --- p.6 / Chapter 1.3 --- Literature Review --- p.8 / Chapter 1.3.1 --- Deterministic Deployment Methods --- p.9 / Chapter 1.3.2 --- Dynamic Deployment Methods --- p.10 / Chapter 1.4 --- A Brief Introduction to Least Squares Analysis --- p.13 / Chapter 1.5 --- Thesis Outline --- p.15 / Chapter 2 --- Mobile Sensor Network Deployment Problem --- p.18 / Chapter 2.1 --- Sensor Coverage Models --- p.18 / Chapter 2.1.1 --- Binary Sensor Models --- p.19 / Chapter 2.1.2 --- Attenuated and Truncated Attenuated Disk Models --- p.20 / Chapter 2.2 --- Problem Statement --- p.23 / Chapter 3 --- Coverage Optimization as Nonlinear Least Squares Problems --- p.26 / Chapter 3.1 --- Introduction --- p.26 / Chapter 3.2 --- Network Deployment as Least Squares Problems --- p.28 / Chapter 3.2.1 --- Assignment of Sample Points --- p.28 / Chapter 3.2.2 --- Least Squares Function --- p.30 / Chapter 3.2.3 --- Gauss-Newton Method --- p.33 / Chapter 3.2.4 --- Solutions --- p.36 / Chapter 3.3 --- Extension to Binary Sensor Models --- p.39 / Chapter 3.3.1 --- Restrictions of Subgradient Methods --- p.40 / Chapter 3.3.2 --- Sigmoid Functions --- p.42 / Chapter 3.4 --- Convergence and Multiple Minima Issues --- p.44 / Chapter 3.4.1 --- Convergence --- p.44 / Chapter 3.4.2 --- Multiple Minima --- p.48 / Chapter 3.5 --- Stopping Criteria --- p.52 / Chapter 3.6 --- Summary --- p.53 / Chapter 4 --- Experimental Results --- p.55 / Chapter 4.1 --- Introduction --- p.55 / Chapter 4.2 --- Numerical Examples --- p.56 / Chapter 4.2.1 --- Examples of Attenuated Disk Models --- p.57 / Chapter 4.2.2 --- Examples of Binary Sensor Models --- p.63 / Chapter 4.3 --- Performance Metrics of Mobile Sensor Deployment Schemes --- p.68 / Chapter 4.4 --- Comparison to Existing Methods --- p.74 / Chapter 4.5 --- Summary --- p.81 / Chapter 5 --- Conclusions --- p.83 / Chapter 5.1 --- Conclusions --- p.83 / Chapter 5.2 --- Future Research Directions --- p.85 / Appendices --- p.87 / Chapter A --- An Overview of Existing Deployment Methods --- p.88 / Chapter A.1 --- Potential Fields and Virtual Forces --- p.88 / Chapter A.2 --- Distributed Self-Spreading Algorithm --- p.92 / Chapter A.3 --- VD-Based Deployment Algorithm --- p.96 / Bibliography --- p.99
123

Least median squares algorithm for clusterwise linear regression.

January 2009 (has links)
Fung, Chun Yip. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 53-54). / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- The Exchange Algorithm Framework --- p.4 / Chapter 2.1 --- Ordinary Least Squares Linear Regression --- p.5 / Chapter 2.2 --- The Exchange Algorithm --- p.6 / Chapter 3 --- Methodology --- p.12 / Chapter 3.1 --- Least Median Squares Linear Regression --- p.12 / Chapter 3.2 --- Least Median Squares Algorithm for Clusterwise Linear Re- gression --- p.16 / Chapter 3.3 --- Measures of Performance --- p.20 / Chapter 3.4 --- An Illustrative Example --- p.24 / Chapter 4 --- Monte Carlo Simulation Study --- p.34 / Chapter 4.1 --- Simulation Plan --- p.34 / Chapter 4.2 --- Simulation Results --- p.41 / Chapter 4.2.1 --- Effects of the Six factors --- p.41 / Chapter 4.2.2 --- Comparisons between LMSA and the Exchange Algorithm --- p.47 / Chapter 4.2.3 --- Evaluation of the Improvement of Regression Parame- ters by Performing Stage 3 in LMSA --- p.50 / Chapter 5 --- Concluding Remarks --- p.51 / Bibliography --- p.52
124

Perceptions of Elementary Educators Toward Inclusion

Stanley, Laurel M 01 May 2015 (has links)
Since the late 1990s there has been a considerable increase in the number of students with disabilities who receive instruction in inclusive settings. The participation of students with disabilities in inclusion classrooms continued to grow with the passing of The No Child Left Behind Act (2001), formerly known as the Elementary and Secondary Education Act. While previous legislation called for students with disabilities to participate in all standardized testing, The No Child Left Behind Act called for the closing of the achievement gap between students with disabilities and their nondisabled peers. An accountability system with sanctions for individual schools and school division not showing gains towards closing the achievement gap was also established with the passing of the No Child Left behind Act, making the progress of students with disabilities a priority for all educators. This qualitative study examined the perceptions of general education teachers, special education teachers, and building level administrators regarding inclusion in the elementary setting. Indepth, structured interviews were conducted with the 12 participants at a time and location of their choosing. Ten interview questions guided the process and the participants’ responses were recorded and transcribed verbatim. Previous qualitative studies have been conducted with varying results. The review of the literature indicates that the perceptions of educators toward inclusion may impact the design and subsequent success of inclusion programs as well as the academic progress of students with disabilities. Many factors seem to contribute to the development of teacher perceptions of inclusion, including professional development training and special education classes taken by general education teachers. The data were analyzed by first coding themes found in the interview responses. The themes were then categorized by using ordering and sorting techniques that permitted emerging patterns to be documented. The findings indicate that the participants of this study do not perceive that inclusion is appropriate for all students with disabilities. The participants cited the following features as being necessary elements of inclusion: coplanning, collaboration, and coteaching between the general education teacher and the special education teacher. Recommendations for practice and for future research were based on the data analysis.
125

Analysis of the United States Hop Market

Dasso, Michael W 01 June 2015 (has links)
Hops are one of the four main ingredients used to produce beer. Many studies have been done to analyze the science behind growing and harvesting hops, creating hop hybrids, and how to brew beer with hops. However, there has been little research done revolving around the economic demand and supply model of the hop market. The objectives of this study are to create an econometric model of supply and demand of hops in the United States from 1981 to 2012, and to identify important exogenous variables that explain the supply and demand of hops using the two-stage least squares (2SLS) method of analysis. Using the 2SLS method, the demand model yielded that the US beer production variable is significant at the 10 percent level. For every 1 percent change in US beer production, there will be a 6.25 percent change in quantity of hops demanded in the same direction. The supply model showed that US acreage is significant at the 1 percent level. For every 1 percent change in US acreage, there will be a 0.889 percent change in quantity of hops supplied in the same direction. The implications of this study are viewed in relation to both producers and consumers.
126

The Least preferred co-worker scale as a predictor of leadership behavior in work settings

Streeter, Jenell Arlene 01 January 1990 (has links)
This study evaluates the construct validity of the Least Preferred Co-worker (LPC) Scale by testing the predictions made by the motivational hierarchy hypothesis. The respondents were one hundred fifty-nine supervisors and managers. The LPC determined leadership style as either relationship-oriented or task-oriented. Situational control was measured by the Leader-Member Relations scale, Task Structure scale, and Position Power scale. Consideration behavior, measured by the adapted LBDQ, reflected a need for interpersonal success. Initiation of structure behaviors, measured by the adapted LBDQ, reflected a need for task success. Two hypotheses were tested: (1) High LPC leaders in high control situations engage in more task-oriented behaviors than high LPC leaders in low control situations. Low LPC leaders' task-oriented behaviors are consistent across situational control. (2) Low LPC leaders in high control situations engage in more consideration behaviors than low LPC leaders in low control situations. High LPC leaders' consideration behaviors are consistent across situational control. The results of this study supplements previous research (Green, Nebeker & Boni, 1976; Michaelson, 1973) supportive of the motivational hierarchy inteipretation of the LPC. Hypothesis 1 was not supported. However, a significant interaction effect supported Hypothesis 2. Criticisms concerning the construct validity of the LPC, the motivational hierarchy inteipretation of the LPC, and the Contingency Model of Leadership Effectiveness are discussed. Several recommendations for future research are suggested.
127

Real Time Digital Signal Processing Adaptive Filters for Correlated Noise Reduction in Ring Laser Gyro Inertial Systems

Doheny, David A. 01 April 2004 (has links)
Existing opportunities in advanced interceptor, satellite guidance and aircraft navigation technologies, requiring higher signal processing speeds and lower noise environments, are demanding Ring Laser Gyro (RLG) based Inertial Systems to reduce initialization and operational data latency as well as correlated noise magnitudes. Existing signal processing algorithms are often less than optimal when considering these requirements. Advancements in micro-electronic processes have made Application Specific Integrated Circuits (ASIC) a fundamental building block for system implementation when considering higher-level signal processing algorithms. Research of real time adaptive signal processing algorithms embedded in ASICs for use in RLG based inertial systems will help to understand the trade-off in finite register length effects to correlated noise magnitude, organizational complexity, computational efficiency, rate of convergence, and numerical stability. Adaptive filter structures selected will directly affect meeting inertial system performance requirements for data latency, residual noise budgets and real time processing throughput. Research in this area will help to target specific adaptive noise cancellation algorithms for RLG based inertial systems in a variety of military and commercial space applications. Of particular significance is an attempt to identify an algorithm embedded in an ASIC that will reduce the correlated noise components to the theoretical limit of the RLG sensor itself. This would support a variety of applications for the low noise space environments that the RLG based inertial systems are beginning to find promise for such as advanced military interceptor technology and commercial space satellite navigation, guidance and control systems.
128

Numerical properties of adaptive recursive least-squares (RLS) algorithms with linear constraints.

Huo, Jia Q. January 1999 (has links)
Adaptive filters have found applications in many signal processing problems. In some situations, linear constraints are imposed on the filter weights such that the filter is forced to exhibit a certain desired response. Several algorithms for linearly constrained least-squares adaptive filtering have been developed in the literature. When implemented with finite precision arithmetic, these algorithms are inevitably subjected to rounding errors. It is essential to understand how these algorithms react to rounding errors.In this thesis, the numerical properties of three linearly constrained least-squares adaptive filtering algorithms, namely, the linearly constrained fast least algorithm, the linear systolic array for MVDR beamforming and the linearly constrained QRD-RLS algorithm, are studied. It is shown that all these algorithms can be separated into a constrained part and an unconstrained part. The numerical properties of unconstrained least-squares algorithms (i.e., the unconstrained part of the linearly constrained algorithms under study) are reviewed from the perspectives of error propagation, error accumulation and numerical persistency. It is shown that persistent excitation and sufficient numerical resolution are needed to ensure the stability of the CRLS algorithm, while the QRD-RLS algorithm is unconditionally stable. The numerical properties of the constrained algorithms are then examined. Based on the technique of how the constraints are applied, these algorithms can be grouped into two categories. The first two algorithms admit a similar structure in that the unconstrained parts preceed the constrained parts. Error propagation analysis shows that this structure gives rise to unstable error propagation in the constrained part. In contrast, the constrained part of the third algorithm preceeds the unconstrained part. It is shown that this algorithm gives an ++ / exact solution to a linearly constrained least-squares adaptive filtering problem with perturbed constraints and perturbed input data. A minor modification to the constrained part of the linearly constrained QRD-RLS algorithm is proposed to avoid a potential numerical difficulty due to the Gaussian elimination operation employed in the algorithm.
129

Random Matrix Theory Analysis of Fixed and Adaptive Linear Receivers

Peacock, Matthew James McKenzie January 2006 (has links)
Doctor of Philosophy (PhD) / This thesis considers transmission techniques for current and future wireless and mobile communications systems. Many of the results are quite general, however there is a particular focus on code-division multiple-access (CDMA) and multi-input multi-output (MIMO) systems. The thesis provides analytical techniques and results for finding key performance metrics such as signal-to-interference and noise power ratios (SINR) and capacity. This thesis considers a large-system analysis of a general linear matrix-vector communications channel, in order to determine the asymptotic performance of linear fixed and adaptive receivers. Unlike many previous large-system analyses, these results cannot be derived directly from results in the literature. This thesis considers a first-principles analytical approach. The technique unifies the analysis of both the minimum-mean-squared-error (MMSE) receiver and the adaptive least-squares (ALS) receiver, and also uses a common approach for both random i.i.d. and random orthogonal precoding. The approach is also used to derive the distribution of sums and products of free random matrices. Expressions for the asymptotic SINR of the MMSE receiver are derived, along with the transient and steady-state SINR of the ALS receiver, trained using either i.i.d. data sequences or orthogonal training sequences. The results are in terms of key system parameters, and allow for arbitrary distributions of the power of each of the data streams and the eigenvalues of the channel correlation matrix. In the case of the ALS receiver, we allow a diagonal loading constant and an arbitrary data windowing function. For i.i.d. training sequences and no diagonal loading, we give a fundamental relationship between the transient/steady-state SINR of the ALS and the MMSE receivers. We demonstrate that for a particular ratio of receive to transmit dimensions and window shape, all channels which have the same MMSE SINR have an identical transient ALS SINR response. We demonstrate several applications of the results, including an optimization of information throughput with respect to training sequence length in coded block transmission.
130

Shooter Localization in a Wireless Sensor Network / Lokalisering av skytt i ett trådlöst sensornätverk

Wilsson, Olof January 2009 (has links)
<p>Shooter localization systems are used to detect and locate the origin of gunfire. A wireless sensor network is one possible implementation of such a system. A wireless sensor network is sensitive to synchronization errors. Localization techniques that rely on the timing will give less accurate or even useless results if the synchronization errors are too large.</p><p>This thesis focuses on the influence of synchronization errors on the abilityto localize a shooter using a wireless sensor network. A localization algorithm</p><p>is developed and implemented and the effect of synchronization errors is studied. The localization algorithm is evaluated using numerical experiments, simulations, and data from real gunshots collected at field trials.</p><p>The results indicate that the developed localization algorithm is able to localizea shooter with quite good accuracy. However, the localization performance is to a high degree influenced by the geographical configuration of the network as well as the synchronization error.</p> / <p><p>Skottlokaliseringssystem används för att upptäcka och lokalisera ursprunget för avlossade skott. Ett trådlöst sensornätverk är ett sätt att utforma ett sådant system.Trådlösa sensornätverk är känsliga för synkroniseringsfel. Lokaliseringsmetoder som bygger på tidsobservationer kommer med för stora synkroniseringsfel ge dåliga eller helt felaktiga resultat.</p><p>Detta examensarbete fokuserar på vilken inverkan synkroniseringsfel har på möjligheterna att lokalisera en skytt i ett trådlöst sensornätverk. En lokaliseringsalgoritm utvecklas och förmågan att korrekt lokalisera en skytt vid olika synkroniseringsfel undersöks. Lokaliseringsalgoritmen prövas med numeriska experiment, simuleringar och även för data från riktiga skottljud, insamlade vid fältförsök.</p><p>Resultaten visar att lokaliseringsalgoritmen fungerar tillfredställande, men att lokaliseringsförmågan till stor del påverkas av synkroniseringsfel men även av sensornätverkets geografiska utseende.</p></p>

Page generated in 0.056 seconds