ETDs

This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.

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A sparsity enforcing framework with TVL1 regularization and its application in MR imaging and source localization

Description
The theme for this work is the development of fast numerical algorithms for sparse optimization as well as their applications in medical imaging and source localization using sensor array processing. Due to the recently proposed theory of Compressive Sensing (CS), the $\ell_1$ minimization problem attracts more attention for its ability…

The theme for this work is the development of fast numerical algorithms for sparse optimization as well as their applications in medical imaging and source localization using sensor array processing. Due to the recently proposed theory of Compressive Sensing (CS), the $\ell_1$ minimization problem attracts more attention for its ability to exploit sparsity. Traditional interior point methods encounter difficulties in computation for solving the CS applications. In the first part of this work, a fast algorithm based on the augmented Lagrangian method for solving the large-scale TV-$\ell_1$ regularized inverse problem is proposed. Specifically, by taking advantage of the separable structure, the original problem can be approximated via the sum of a series of simple functions with closed form solutions. A preconditioner for solving the block Toeplitz with Toeplitz block (BTTB) linear system is proposed to accelerate the computation. An in-depth discussion on the rate of convergence and the optimal parameter selection criteria is given. Numerical experiments are used to test the performance and the robustness of the proposed algorithm to a wide range of parameter values. Applications of the algorithm in magnetic resonance (MR) imaging and a comparison with other existing methods are included. The second part of this work is the application of the TV-$\ell_1$ model in source localization using sensor arrays. The array output is reformulated into a sparse waveform via an over-complete basis and study the $\ell_p$-norm properties in detecting the sparsity. An algorithm is proposed for minimizing a non-convex problem. According to the results of numerical experiments, the proposed algorithm with the aid of the $\ell_p$-norm can resolve closely distributed sources with higher accuracy than other existing methods.
ContributorsShen, Wei (Author) / Mittlemann, Hans D (Thesis advisor) / Renaut, Rosemary A. (Committee member) / Jackiewicz, Zdzislaw (Committee member) / Gelb, Anne (Committee member) / Ringhofer, Christian (Committee member) / Arizona State University (Publisher)
Created2011
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新冠疫情背景下按揭压力与自雇卡车司机经营行为研究

Description自雇司机是公路货运司机中比例人数最多、最基层的一员，他们在公路物流行业中扮演着极为重要的角色，他们承担着各种来源的压力。本文以疫情前后按揭购买卡车的自雇司机为研究样本，基于本研究收集到的独特数据，研究发现自雇卡车司机在面临按揭压力时，倾向采取更为激进的经营及驾驶行为，表现为更少的休息天数、更长的工作时长以及更危险的高速驾驶行为，并在一系列稳健性检验中基本结论仍然存在；基于新冠疫情事件研究发现，新冠疫情带来的非预期性经济停摆和收入中断，导致疫情前的发生的按揭贷款的卡车司机面临更强的还款压力，在经济恢复后面对按揭压力更有可能采用激进的经营和驾驶行为；进一步，通过机制检验研究本文发现这种按揭压力主要表现为担心当前或者未来发生不能及时偿还按揭款。再者，基于人格性征和家庭支持的调节效应检验，本文发现神经质人格特征、谨慎尽责性人格特征以及工作压力感没有在按揭压力与自雇卡车司机激进的经营和驾驶选择上起到调节作用，这可能是自雇卡车司机面临的按揭压力都很大，个体性格特征很大程度无法缓和其压力感，而家庭的支持和家庭-工作平衡可以有效缓解自雇卡车司机面临按揭压力时提高工作时长和危险驾驶行为的倾向。 最后，本文设计一项随机对照干预实验，向自雇卡车司机发送短息或者微信，提醒他们避免疲劳驾驶和危险超速驾驶，然后观察发送短信微信前后自雇卡车司机经营及驾驶行为的变化，识别考察外界积极主动的关心和提醒能否起到相应的后果。本文发现对自雇卡车司机获得外部主动积极地的关心和提醒，在面临按揭压力时意识到简单地减少休息增加运营时长以及采用危险驾驶行为抢时间的策略可能给其带来很大的风险，从而相应地缓解对按揭压力的过度反应；进一步调节作用检验表明，短信干预实验在神经质和谨慎尽责性人格司机中起到更大的减缓作用，同时家庭支持较少时短信干预实现效应也更为明显。
ContributorsMa, Liqun (Author) / Shen, Wei (Thesis advisor) / Wu, Fei (Thesis advisor) / Zhang, Zhen (Committee member) / Arizona State University (Publisher)
Created2021
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激情如何影响高校毕业生就业方向？—以中国音乐类硕士研究生为例

Description进入新时代，我国的经济、社会、文化和教育事业迅速发展，艺术类生源肩负着我国优秀传统文化复兴、保护、传承与发展的历史使命。“艺考热”持续多年不衰，但艺术类生源的就业率近年却持续走低，学艺期望与就业失望的矛盾突出。本论文以影响音乐类硕士研究生就业的相关自变量和因变量因素为出发点，通过文献梳理、数据分析、比较研究、问卷调查与口述访谈等研究方法，对 300 余名音乐类硕士研究生的就业情况及相关因素，进行了大量的数据收集、建模和实证分析，研究了“激情” 这一关键因素对音乐类硕士研究生就业的影响。 本论文通过实证研究，对国家艺术教育政策的改进与完善；对艺术类高校人才培养模式的优化；对艺术类人才自身质量的提升等，提出一系列具有数据支撑的意见和建议。
ContributorsJin, Tingting (Author) / Shen, Wei (Thesis advisor) / Wu, Fei (Thesis advisor) / Zhang, Zhen (Committee member) / Arizona State University (Publisher)
Created2021