Self-adaptive algorithms for quasiconvex programming and applications to machine learning

For solving a broad class of nonconvex programming problems on an unbounded constraint set, we provide a self-adaptive step-size strategy that does not include line-search techniques and establishes the convergence of a generic approach under mild assumptions. Specifically, the objective function may not satisfy the convexity condition. Unlike descent line-search algorithms, it does not need a known Lipschitz constant to figure out how big the first step should be. The crucial feature of this process is the steady reduction of the step size until a certain condition is fulfilled. In particular, it can provide a new gradient projection approach to optimization problems with an unbounded constrained set. The correctness of the proposed method is verified by preliminary results from some computational examples. To demonstrate the effectiveness of the proposed technique for large-scale problems, we apply it to some experiments on machine learning, such as supervised feature selection, multi-variable logistic regressions and neural networks for classification

First principle modeling of alcohol fuel cell catalysis

Ph.DDOCTOR OF PHILOSOPH

Determinants of Preference/Intention to Use Condoms Among Unmarried Youths in Vietnam

Introduction: This dissertation examined determinants of "condom preference/intention" by unmarried youths in Vietnam. Method: Data were collected in August 2004 using interviews with structured questionnaires. Analysis involved 1337 young unmarried people aged 15-24 years. Logistic regression models were used to examine associations of the following independent variables: perceived accessibility to contraceptive and HIV information; exposure to information about contraceptives, HIV and STIs; and discussion about contraceptives, HIV and STIs with "condom preference/intention". Logistic regression models, together with plotting techniques, were used to examine moderation effects of perceived availability and perceived accessibility to contraceptives on the relationships between conception knowledge, contraceptive awareness, and HIV/STIs knowledge with "condom preference/intention". Finally, Structural Equation Modeling technique (SEM) was used to examine mediation effects of conception knowledge, contraceptive awareness, and HIV/STIs knowledge on the relationships between each of the independent variables with "condom preference/intention". Results: Perceived accessibility to contraceptive information, perceived accessibility to HIV information, and exposure to contraceptive information were found as the strongest determinants of "condom preference/intention". Conception knowledge was found to mediate the relationships between perceived accessibility to contraceptive information, perceived accessibility to HIV information, and exposure to contraceptive information with "condom preference/intention". Contraceptive awareness was found to mediate the relationship between perceived accessibility to HIV information, and exposure to contraceptive information with "condom preference/intention". HIV/STIs knowledge was found to mediate the relationships between perceived accessibility to contraceptive information, and between perceived accessibility to HIV information with condom preference/intention. Finally, perceived availability of contraceptives was found to moderate the relationship between conception knowledge and condom preference/intention. Implications: Evaluation needs to pay close attention to the mediation and moderation relationships among factors explaining intended condom use. Interventions should address multiple channels to disseminate and make highly accessible and available the amount of information about conception, contraceptives, HIV, and STIs. Close attention should be paid in order to ensure effective discussions about these topics through different sources. Condoms should be highly available within an effective communication system

Full-Duplex Enabled Mobile Edge Caching: From Distributed to Cooperative Caching

Mobile edge caching (MEC) has received much attention as a promising technique to overcome the stringent latency and data hungry requirements in future generation wireless networks. Meanwhile, full-duplex (FD) transmission can potentially double the spectral efficiency by allowing a node to receive and transmit in the same time/frequency block simultaneously. In this paper, we investigate the delivery time performance of full-duplex enabled MEC (FD-MEC) systems, in which the users are served by distributed edge nodes (ENs), which operate in FD mode and are equipped with a limited storage memory. Firstly, we analyse the FD-MEC with different levels of cooperation among the ENs and take into account a realistic model of self-interference cancellation. Secondly, we propose a framework to minimize the system delivery time of FD-MEC under both linear and optimal precoding designs. Thirdly, to deal with the non-convexity of the formulated problems, two iterative optimization algorithms are proposed based on the inner approximation method, whose convergence is analytically guaranteed. Finally, the effectiveness of the proposed designs are demonstrated via extensive numerical results. It is shown that the cooperative scheme mitigates inter-user and self interference significantly better than the distributed scheme at an expense of inter-EN cooperation. In addition, we show that minimum mean square error (MMSE)-based precoding design achieves the best performance-complexity trade-off, compared with the zero-forcing and optimal designs

Real-time wavefront processors for the next generation of adaptive optics systems: a design and analysis

Adaptive optics (AO) systems currently under investigation will require at least two orders of magitude increase in the number of actuators, which in turn translates to effectively a 104 increase in compute latency. Since the performance of an AO system invariably improves as the compute latency decreases, it is important to study how today's computer systems will scale to address this expected increase in actuator utilization. This paper answers this question by characterizing the performance of a single deformable mirror (DM) Shack-Hartmann natural guide star AO system implemented on the present-generation digital signal processor (DSP) TMS320C6701 from Texas Instruments. We derive the compute latency of such a system in terms of a few basic parameters, such as the number of DM actuators, the number of data channels used to read out the camera pixels, the number of DSPs, the available memory bandwidth, as well as the inter-processor communication (IPC) bandwidth and the pixel transfer rate. We show how the results would scale for future systems that utilizes multiple DMs and guide stars. We demonstrate that the principal performance bottleneck of such a system is the available memory bandwidth of the processors and to lesser extent the IPC bandwidth. This paper concludes with suggestions for mitigating this bottleneck

Improvement of Tuning Fork Gyroscope Drive-mode Oscillation Matched using a Differential Driving Suspension Frame

This paper presents a novel design of a vibration tuning fork gyroscope (TFG) based on a differential driving suspension coupling spring between two gyroscopes. The proposed TFG is equivalent to a transistor differential amplifier circuit. The mechanical vibrations of driving frames are, therefore, well matched. The matching level depends on stiffness of spring. When three various TFG structures respond to differential stiffness of spring, their the driving frame mechanical vibration is well matched in case the input excitation driving differential phase is less than 3.5°, 2.5°, and 4°, respectively. The fabricated tuning fork gyroscope linearly operates in the range from -200 to +200 degree/s with the resolution of about 0.45 mV/degree/s

Some properties of the positive boolean dependencies in the database model of block form

The report proposes the concept of positive boolean dependency in the database model of block form, proving equivalent theorem of three derived types, necessary and sufficient criteria of the derived type, the member problem... In addition, some properties related to this concept in the case of block r degenerated into relation are also expressed and demonstrated here