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- Genre: Doctoral Dissertation
- Creators: Shen, Wei
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 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
Description
Radio frequency (RF) transceivers require a disproportionately high effort in terms of test development time, test equipment cost, and test time. The relatively high test cost stems from two contributing factors. First, RF transceivers require the measurement of a diverse set of specifications, requiring multiple test set-ups and long test times, which complicates load-board design, debug, and diagnosis. Second, high frequency operation necessitates the use of expensive equipment, resulting in higher per second test time cost compared with mixed-signal or digital circuits. Moreover, in terms of the non-recurring engineering cost, the need to measure complex specfications complicates the test development process and necessitates a long learning process for test engineers. Test time is dominated by changing and settling time for each test set-up. Thus, single set-up test solutions are desirable. Loop-back configuration where the transmitter output is connected to the receiver input are used as the desirable test set- up for RF transceivers, since it eliminates the reliance on expensive instrumentation for RF signal analysis and enables measuring multiple parameters at once. In-phase and Quadrature (IQ) imbalance, non-linearity, DC offset and IQ time skews are some of the most detrimental imperfections in transceiver performance. Measurement of these parameters in the loop-back mode is challenging due to the coupling between the receiver (RX) and transmitter (TX) parameters. Loop-back based solutions are proposed in this work to resolve this issue. A calibration algorithm for a subset of the above mentioned impairments is also presented. Error Vector Magnitude (EVM) is a system-level parameter that is specified for most advanced communication standards. EVM measurement often takes extensive test development efforts, tester resources, and long test times. EVM is analytically related to system impairments, which are typically measured in a production test i environment. Thus, EVM test can be eliminated from the test list if the relations between EVM and system impairments are derived independent of the circuit implementation and manufacturing process. In this work, the focus is on the WLAN standard, and deriving the relations between EVM and three of the most detrimental impairments for QAM/OFDM based systems (IQ imbalance, non-linearity, and noise). Having low cost test techniques for measuring the RF transceivers imperfections and being able to analytically compute EVM from the measured parameters is a complete test solution for RF transceivers. These techniques along with the proposed calibration method can be used in improving the yield by widening the pass/fail boundaries for transceivers imperfections. For all of the proposed methods, simulation and hardware measurements prove that the proposed techniques provide accurate characterization of RF transceivers.
ContributorsNassery, Afsaneh (Author) / Ozev, Sule (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Kiaei, Sayfe (Committee member) / Kitchen, Jennifer (Committee member) / Arizona State University (Publisher)
Created2013
Description
Asymptotic and Numerical methods are popular in applied electromagnetism. In this work, the two methods are applied for collimated antennas and calibration targets, respectively. As an asymptotic method, the diffracted Gaussian beam approach (DGBA) is developed for design and simulation of collimated multi-reflector antenna systems, based upon Huygens principle and independent Gaussian beam expansion, referred to as the frames. To simulate a reflector antenna in hundreds to thousands of wavelength, it requires 1E7 - 1E9 independent Gaussian beams. To this end, high performance parallel computing is implemented, based on Message Passing Interface (MPI). The second part of the dissertation includes the plane wave scattering from a target consisting of doubly periodic array of sharp conducting circular cones by the magnetic field integral equation (MFIE) via Coiflet based Galerkin's procedure in conjunction with the Floquet theorem. Owing to the orthogonally, compact support, continuity and smoothness of the Coiflets, well-conditioned impedance matrices are obtained. Majority of the matrix entries are obtained in the spectral domain by one-point quadrature with high precision. For the oscillatory entries, spatial domain computation is applied, bypassing the slow convergence of the spectral summation of the non-damping propagating modes. The simulation results are compared with the solutions from an RWG-MLFMA based commercial software, FEKO, and excellent agreement is observed.
ContributorsWang, Le, 1975- (Author) / Pan, George (Thesis advisor) / Yu, Hongyu (Committee member) / Aberle, James T., 1961- (Committee member) / Diaz, Rodolfo (Committee member) / Kitchen, Jennifer (Committee member) / Arizona State University (Publisher)
Created2012
Description
Programmable Metallization Cell (PMC) is a resistance-switching device based on migration of nanoscale quantities of cations in a solid electrolyte and formation of a conducting electrodeposit by the reductions of these cations. This dissertation presents electrical characterization results on Cu-SiO2 based PMC devices, which due to the na- ture of materials can be easily integrated into the current Complimentary metal oxide semiconductor (CMOS) process line. Device structures representing individual mem- ory cells based on W bottom electrode and n-type Si bottom electrode were fabricated for characterization. For the W bottom electrode based devices, switching was ob- served for voltages in the range of 500mV and current value as low as 100 nA showing the electrochemical nature and low power potential. The ON state showed a direct de- pendence on the programming current, showing the possibility of multi-bit storage in a single cell. Room temperature retention was demonstrated in excess of 105 seconds and endurance to approximately 107 cycles. Switching was observed for microsecond duration 3 V amplitude pulses. Material characterization results from Raman, X-ray diffraction, Rutherford backscattering and Secondary-ion mass spectroscopy analysis shows the influence of processing conditions on the Cu concentration within the film and also the presence of Cu as free atoms. The results seemed to indicate stress-induced void formation in the SiO2 matrix as the driving mechanism for Cu diffusion into the SiO2 film. Cu/SiO2
Si based PMC devices were characterized and were shown to have inherent isolation characteristics, proving the feasibility of such a structure for a passive array. The inherent isolation property simplifies fabrication by avoiding the need for a separate diode element in an array. The isolation characteristics were studied mainly in terms of the leakage current. The nature of the diode interface was further studied by extracting a barrier potential which shows it can be approximated to a Cu-nSi metal semiconductor Schottky diode.
Si based PMC devices were characterized and were shown to have inherent isolation characteristics, proving the feasibility of such a structure for a passive array. The inherent isolation property simplifies fabrication by avoiding the need for a separate diode element in an array. The isolation characteristics were studied mainly in terms of the leakage current. The nature of the diode interface was further studied by extracting a barrier potential which shows it can be approximated to a Cu-nSi metal semiconductor Schottky diode.
ContributorsPuthenthermadam, Sarath (Author) / Kozicki, Michael N (Thesis advisor) / Diaz, Rodolfo (Committee member) / Schroder, Dieter K. (Committee member) / Alford, Terry (Committee member) / Arizona State University (Publisher)
Created2011
Description本文对中国制药企业并购溢价影响因素进行了研究，提出了对制药企业并购非常重要的两个新的影响因素：可生产药品批文和在研新药批文。本文以2011年1月—2019年12月间我国制药行业上市公司并购事件为样本，对在研新药和可生产药品批文的价值从四个维度度量：是否有在研新药和可生产药品批文；在研新药数量及可生产药品批文数量；根据创新药和仿制药两个类别进行细分；标的企业所拥有的在研新药和可生产药品批文的市场价值。论文发现药品批文对企业并购溢价的影响不是很显著。进一步的，本文探究了药品批文对主并企业的对被并购公司的估值的影响。实证结果表明，我国制药企业在并购估值时确实会考虑到在研新药和可生产药品批文的价值。本文还发现对于可生产药品来说，相对创新药，被并购公司持有的仿制药批文影响更显著。而对于在研新药来说，主并企业更看重在研的创新药，在研仿制药对并购估值的影响不大。最后，本文选取了两个代表性案例进一步分析和探讨药品批文对企业并购的影响。
ContributorsYe, Tao (Author) / Shen, Wei (Thesis advisor) / Chang, Chun (Thesis advisor) / Jiang, Zhan (Committee member) / Gu, Bin (Committee member) / Arizona State University (Publisher)
Created2022
Description汽车行业属于国家支柱型产业，创造了高额的产值，增加了就业岗位。随着汽车生产行业竞争日趋激烈的趋势影响，汽车经销商在未来会出现明显的分化，并且逐步向头部集中。基于这样的行业背景，本项研究开展汽车经销商整体经营和盈利能力等方面的详细深入分析，即系统整合汽车经销商业务运营层面和财务层面数据，结合统计研究方法，对经销商盈利能力进行系统且详实归因分析，从而试别驱动盈利能力的关键业务要素。其研究成果能够完善对行业发展规律和经营模式系统性理解，从而进一步指导该领域的相关业务实践，提高经销商整体经营业绩。本课题通过四个阶段来开展经销商整体经营与盈利归因的相关研究。首先，本课题梳理了中国汽车消费行业发展的历史，同时阐述样本期内（2018-2020年）国内宏观经济和汽车消费市场的特征进行，并介绍X品牌汽车经销商的地理分布、资质和业绩评级体系、自身经营特征以及汽车生产商对经销商扶持政策等方面。在第二阶段，本课题聚焦研究假设、模型与方法，通过对X品牌汽车经销商的业务结构和运营管理开展分析，并逐步识别影响经销商盈利的关键指标变量，并提出研究假设和相关模型（即时间序列模型和面板回归模型）。在第三阶段，本课题首先开展经销商相关信息整体性统计分析，获得关键业务指标在样本期内动态特征，并结合时间序列回归模型探讨各项业务指标对经销商整体盈利能力的影响程度。在第四阶段，本课题采用（个体）固定效应的面板回归模型来研究不同组别（控制）条件下经销商盈利能力的影响因素以及其盈利能力对这些因素的敏感程度，从而更深入和全面地揭示影响经销商盈利能力的潜在因素。
基于上述四阶段的研究结果，本研究进一步就提升经销商盈利能力展开讨论，并提出相应对策。本课题相关结论仅从X品牌汽车经销商经营和财务数据进行定性和定量分析获得，但衷心希望本研究的成果能够对汽车经销商改善经营业务方面能起到实践上的借鉴和指导意义。
ContributorsPan, Guangxiong (Author) / Shen, Wei (Thesis advisor) / Wu, Fei (Thesis advisor) / Zhu, Qigui (Committee member) / Arizona State University (Publisher)
Created2022
Description
The world has seen a revolution in cellular communication with the advent of 5G, which enables gigabits per second data speed with low latency, massive capacity, and increased availability. Complex modulated signals are used in these moderncommunication systems to achieve high spectral efficiency, and these signals exhibit high peak to average power ratios (PAPR). Design of cellular infrastructure hardware to support these complex signals therefore becomes challenging, as the transmitter’s radio frequency power amplifier (RF PA) needs to remain highly efficient at both peak and backed off power conditions. Additionally, these PAs should exhibit high linearity and support continually increasing bandwidths. Many advanced PA configurations exhibit high efficiency for processing legacy communications signals. Some of the most popular architectures are Envelope Elimination and Restoration (EER), Envelope Tracking (ET), Linear Amplification using Non-linear Component (LINC), Doherty Power Amplifiers (DPA), and Polar Transmitters. Among these techniques,
the DPA is the most widely used architecture for base-station applications because of its simple configuration and ability to be linearized using simple digital pre-distortion (DPD) algorithms. To support the cellular infrastructure needs of 5G and beyond, RF PAs, specifically DPA architectures, must be further enhanced to support broader bandwidths as well as smaller form-factors with higher levels of integration. The following four novel works are presented in this dissertation to support RF PA requirements for future cellular infrastructure:
1. A mathematical analysis to analyze the effects of non-linear parasitic capacitance (Cds) on the operation of continuous class-F (CCF) mode power amplifiers and identify their optimum operating range for high power and efficiency.
2. A methodology to incorporate a class-J harmonic trapping network inside the PA package by considering the effect of non-linear Cds, thus reducing the DPA footprint while achieving high RF performance.
3. A novel method of synthesizing the DPA’s output combining network (OCN) to realize an integrated two-stage integrated LDMOS asymmetric DPA.
4. A novel extended back-off efficiency range DPA architecture that engineers the mutual interaction between combining load and peaking off-state impedance. The theory and architecture are verified through a GaN-based DPA design.
ContributorsAhmed, Maruf Newaz (Author) / Kitchen, Jennifer (Thesis advisor) / Aberle, James (Committee member) / Bakkaloglu, Bertan (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2022
Description
Impedance is one of the fundamental properties of electrical components, materials, and waves. Therefore, impedance measurement and monitoring have a wide range of applications. The multi-port technique is a natural candidate for impedance measurement and monitoring due to its low overhead and ease of implementation for Built-in Self-Test (BIST) applications. The multi-port technique can measure complex reflection coefficients, thus impedance, by using scalar measurements provided by the power detectors. These power detectors are strategically placed on different points (ports) of a passive network to produce unique solution. Impedance measurement and monitoring is readily deployed on mobile phone radio-frequency (RF) front ends, and are combined with antenna tuners to boost the signal reception capabilities of phones. These sensors also can be used in self-healing circuits to improve their yield and performance under process, voltage, and temperature variations. Even though, this work is preliminary interested in low-overhead impedance measurement for RF circuit applications, the proposed methods can be used in a wide variety of metrology applications where impedance measurements are already used. Some examples of these applications include determining material properties, plasma generation, and moisture detection. Additionally, multi-port applications extend beyond the impedance measurement. There are applications where multi-ports are used as receivers for communication systems, RADARs, and remote sensing applications. The multi-port technique generally requires a careful design of the testing structure to produce a unique solution from power detector measurements. It also requires the use of nonlinear solvers during calibration, and depending on calibration procedure, measurement. The use of nonlinear solvers generates issues for convergence, computational complexity, and resources needed for carrying out calibrations and measurements in a timely manner. In this work, using periodic structures, a structure where a circuit block repeats itself, for multi-port measurements is proposed. The periodic structures introduce a new constraint that simplifies the multi-port theory and leads to an explicit calibration and measurement procedure. Unlike the existing calibration procedures which require at least five loads and various constraints on the load for explicit solution, the proposed method can use three loads for calibration. Multi-ports built with periodic structures will always produce a unique measurement result. This leads to increased bandwidth of operation and simplifies design procedure. The efficacy of the method demonstrated in two embodiments.
In the first embodiment, a multi-port is directly embedded into a matching network to measure impedance of the load.
In the second embodiment, periodic structures are used to compare two loads without requiring any calibration.
ContributorsAvci, Muslum Emir (Author) / Ozev, Sule (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Kitchen, Jennifer (Committee member) / Trichopoulos, Georgios (Committee member) / Arizona State University (Publisher)
Created2023
Description
Modern-day automobiles are becoming more connected and reliant on wireless connectivity. Thus, automotive electronics can be both a cause of and highly sensitive to electromagnetic interference (EMI), and the consequences of failure can be fatal. Technology advancements in engineering have brought several features into the automotive field but at the expense of electromagnetic compatibility issues. Automotive EMC problems are the result of the emissions from electronic assemblies inside a vehicle and the susceptibility of the electronics when exposed to external EMI sources. In both cases, automotive EMC problems can cause unintended changes in the automotive system operation. Robustness to electromagnetic interference (EMI) is one of the primary design aspects of state-of-the-art automotive ICs like System Basis Chips (SBCs) which provide a wide range of analog, power regulation and digital functions on the same die. One of the primary sources of conducted EMI on the Local Interconnect Network (LIN) driver output is an integrated switching DC-DC regulator noise coupling through the parasitic substrate capacitance of the SBC. In this dissertation an adaptive active EMI cancellation technique to cancel the switching noise of the DC-DC regulator on the LIN driver output to ensure electromagnetic compatibility (EMC) is presented. The proposed active EMI cancellation circuit synthesizes a phase synchronized cancellation pulse which is then injected onto the LIN driver output using an on-chip tunable capacitor array to cancel the switching noise injected via the substrate. The proposed EMI reduction technique can track and cancel substrate noise independent of process technology and device parasitics, input voltage, duty cycle, and loading conditions of the DC-DC switching regulator. The EMI cancellation system is designed and fabricated on a 180nm Bipolar-CMOS-DMOS (BCD) process with an integrated power stage of a DC-DC buck regulator at a switching frequency of 2MHz along with an automotive LIN driver. The EMI cancellation circuit occupies an area of 0.7 mm2, which is less than 3% of the overall area in a standard SBC and consumes 12.5 mW of power and achieves 25 dB reduction of conducted EMI in the LIN driver output’s power spectrum at the switching frequency and its harmonics.
ContributorsRay, Abhishek (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Kitchen, Jennifer (Committee member) / Seo, Jae-Sun (Committee member) / Arizona State University (Publisher)
Created2023
Description新世纪以来中国电影的产业化改革与探索愈发呈现良好的态势，国产院线电影也在实践中努力赢得观众和票房市场。其中类型喜剧电影，最符合商业电影规律、最顺应影视市场需求、最能获得票房收益而备受影视创投机构、制作公司青睐。本论文研究对象聚焦类型喜剧电影，通过“欢声笑语里的财富”现象，探究类型喜剧电影内部本体构成要素与外部客观促成要素的关联；以通过分析自变量与因变量因素对中国电影票房之类型喜剧影响因素进行实证研究，为影视创投和影视制作总结并提供可靠建议。
本论文整体结构包括：第一部分为导论，包括研究背景、目的意义，相关文献综述与文献评述和论文创新性。第二部分聚焦类型喜剧本身，从电影学范畴的电影本体出发，探究“笑”的心理、社会与文化内涵，并分析将“笑”对经济领域的延伸。第三部分以影视投资、票房为依托，从现象和数据中探寻影响类型喜剧电影的因素，为展开中国电影票房之类型喜剧影响因素实证研究做好理论的铺垫。第四与第五部分则基于上述理论进行实证检验，选用2013-2020年电影样本，采用多元线性回归模型研究喜剧类型对票房的吸引力，以及不同种类型喜剧对电影票房的提振效果作用差异。研究发现喜剧电影对电影票房有显著的提振作用；以及研究电影的外部影响因素（续集效应）对电影票房的作用。发现续集电影有更好的票房表现，续集效应的票房提升作用在喜剧电影中表现的更加明显。
本论文研究成果最终将回归到“欢声笑语里的财富”本身；即“类型复合喜剧”对促进电影与金融产业的互动关联、实现更加可持续化发展，以及进而推动经济及文化业的发展。
ContributorsLiu, Yongqian (Author) / Shen, Wei (Thesis advisor) / Zhu, Ning (Thesis advisor) / Dong, Xiaodan (Committee member) / Arizona State University (Publisher)
Created2022