This thesis describes the research, design, and development of a mid-drive wheelchair for use by the elders living independently, in assisted living facilities, and in nursing homes created by a design team at Georgia Tech's Center for Assistive Technology and Environmental Access (CATEA). This wheelchair stands to significantly improve the mobility of elders through better drive wheel placement and design features that could stand to improve their quality of life.

Drive-by download is a sort of network attack which uses different techniques to plant malicious codes in their computers. It makes the traditional intrusion detection systems and firewalls nonfunctional in the reason that those devices could not detect web-based threats. The Crawler-based approach has been proposed by many studies to discover drive-by download sites. However, the Crawler-based approach could not simulate the real user behavior of web browsing when drive-by download attack happens. Therefore, this study proposes a new approach to detect drive-by download by sniffing HTTP flow. This study uses reputation system to improve the efficiency of client honeypots, and adjusts client honeypots to process the raw data of HTTP flow. In the experiment conducted in real network environment, this study show the performance of a single client honeypot could reach average 560,000 HTTP success access log per day. Even in the peak traffic, this mechanism reduced the process time to 22 hours, and detected drive-by download sites that users were actually browsing. Reputation system in this study is applicable to varieties of domain names because it does not refer to online WHOIS database. It established classification model on machine learning in 12 features. The correct classification rate of the reputation system applied in this study is 90.9%. Compared with other Reputation System studies, this study not only extract features from DNS A-Type but also extract features from DNS NS-Type. The experiment results show the Error Rate of the new features from DNS NS-Type is only 19.03%.

Induction motors are commonly used in numerous industrial applications. To maintain a reliable operation of the motor, it is important to identify the potential faults that may cause the motor to fail. Bearing failures are one of the main causes of motor breakdown. The causes of bearing damage have been studied in detail for a long time. In some cases, bearing failed due to the current passing through them. In this thesis, bearing currents in an inverter driven five-phase induction motor are studied and a new solution is proposed. First, theory of shaft voltage and bearing current are presented. The causes are identified and current solutions are discussed. Then, new switching patterns are proposed for the five-phase induction motor. The new schemes apply a modified algorithm for the space vector pulse-width-modulation (SVPWM). The system is simulated and the results of the new switching patterns are compared with the conventional switching pattern. Finally, the new schemes are experimentally tested using a digital signal processor (DSP) to drive the five-phase IGBT inverter. The experimental results verified that the new switching pattern could reduce shaft voltages and bearing current without affecting the performance.

The switched reluctance motor has the advantages of the low production cost, high operating efficiency, high stability, and high start torque. It can deliver a wide speed range, and therefore make it very attractive to the engineers and researchers. The double salient structure of SRM result in a non-linear stator inductance, so the output reluctance torque has a highly non-linear behavior. A digital signal processor based drive system for SRM is developed and implemented in this thesis using the TI TMS320F240 DSP system which is with universal peripheral interface circuits. The built-in pulse width modulation(PWM) module of the DSP system can auto-generate PWM output signal by setting the relative registers to simplify the hardware design. This research built a complete drive system for SRM, both the closed-loop velocity controller and current compensator were designed according to the proportional-integral(PI) control mechanism, and all schemes were coded in the DSP program. Simulation and experiment results demonstrate that the proposed drive system makes reluctance torque output very smoothly with a preferable velocity response.

This paper designs and implements a DSP-microprocessor based variable frequency motor drive. We control the induction motor with V/F scheme. This paper also analysis about Sine-PWM and Space-Vector-PWM. Compared with commonly used SPWM method, SVPWM has the advantages of higher voltage utilization, lower harmonic and lower switching loss. Also, it increases the efficiency of an inverter. To calculate duty cycle this paper support different update model, so symmetrical and asymmetrical PWM are generated. To analyse about spectra, and we can find the asymmetrical PWM restrain the harmonic.

Abstract: This paper designs and implements a DSP-microprocessor based motor driver. We control the induction motor with V/F scheme. And we module all circuits with PCB Layout.This Inverter is compose of digital board and analog-power board. We connect two parts, and we use a three phase induction motorto to be the load. Because the digital board is compose of DSP, it is to fit a lot of mathematics. It is easy to use the software to present the theory. So the paper compute the three phase gate signals with asymmetrical Pulse-Width-Modulation model.

The thesis will be established as digital Inverter with analog power board and DSP kernel. We can accomplish effective ac motor control with VVVF mode by powerful arithmetic ability of DSP. Furthermore, we can obtain rotor speed by calculating the feedback voltage and current of motor from sensors. We adopt the new integrator scheme to replace traditional pure integrator to solve the dc drift and initial value problems. Meanwhile, we can compensate the voltage distortion caused by dead time to decrease current ripple via judging the direction of current. Because we have modulized our circuits, it is very convenient that we can achieve modern control theories by software modification only.

Because of the convenience of the Internet, we rely closely on the Internet to do information searching and sharing, forum discussion, and online services. However, most of the websites we visit are developed by people with limited security knowledge, and this condition results in many vulnerabilities in web applications. Unfortunately, hackers have successfully taken advantage of these vulnerabilities to inject malicious JavaScript into compromised web pages to trigger drive-by download attacks. Based on our long time observation of malicious web pages, malicious web pages have unusual behavior for evading detection which makes malicious web pages different form normal ones. Therefore, we propose a client-side malicious web page detection mechanism named Web Page Checker (WPC) which is based on anomaly behavior tracing and analyzing to identify malicious web pages. The experimental results show that our method can identify malicious web pages and alarm the website visitors efficiently.

For the readers of White Noise, the first issue he or she has to deal with is the relationship between the society and the individual. But DeLillo was never straightforward in Jack¡¦s narrative. From time to time, the reader is asked to judge by themselves about the authorial intention and the narrator¡¦s attitude toward the characters¡¦ suffering. As both the narrator and a character, Jack Gladney typifies the tension of locating the hope of resistance in a seemingly hopeless situation. As the narrator, Jack¡¦s attitude toward the corrupting force of the society would seem to vacillate among indifference and affirmation. Yet, his indifference would appear to be sarcastic or even accusatory if one remembers that he or she is reading one of DeLillo¡¦s novels. The interpretive deadlock, then, can be summarized into the following question: if DeLillo intended to posit the possibility of resistance through the process of writing and reading, how can it be realized in the protagonist with whom the reader is invited to identify? Numerous approaches are adopted by the critics, and yet the enigmatic ending of the novel continues to challenge the results of their efforts. With ease, Jack Gladney returns to his normal routine after he nearly kills a man, but it is indicated that he is never the same person as exhibited in the previous chapters. To determine the nature of transformation and its implication for the existence of hope, this thesis sets out to dissect the important elements in the last chapter. As the novel ends in Jack¡¦s shopping, the chapter two of this thesis traces the influence of capitalism on the characters. It is found that the characters¡¦ enjoyment of the consumerism is correlative with a fundamental imperfection in their sense of self. In narrating the stories about him, Jack Gladney cannot hide his anxiety for failing to be a good professor, husband and father. From a Lacanian perspective, the disjointedness reveals the failure of the system to provide all his needs. Still, Jack and others are spurred to immerse harder in the ever-revolutionizing mode of enjoyment, endlessly deferring from confronting the void inherent in all their pursuits. Before Jack returns to shop for the last time in the novel, however, he is infected by toxic substance that causes him to eye the capitalist system with suspicion. During the outbreak of the disaster, the New Age belief system, painful enjoyment and environmental crisis are associated with the oppressive force of capitalist development. They all reappear in the end of the novel, yet they are no longer threats for Jack; instead, he finds them enjoyable. In the chapter three of this thesis, my analysis recounts how the characters¡¦ reluctance to depart from their routine of enjoyment contributes to their intentional disavowals of the injuries the system brings to them. In Jack¡¦s case, the biopolitical control that results in the elevation of the status of medical science and enjoyment causes him to resubmit himself more violently to the system. He becomes a killer and enjoys seeing himself as such who seems to contribute to all the subjects in the capitalist society. It is after such sad transformation that the final chapter begins, suddenly deflating the emotional turbulences accumulated throughout the previous chapters. The enigmatic vacuum is still accompanied by signs of Jack¡¦s transformation. However, the omnipresence of death in the chapter seems to weaken the certainty for a pessimistic future of suffering in the capitalist system. Waiting before the checking out point, Jack is in fact facing to the end of vicious circle symbolically. The unfathomable death corresponds with the impossibility the reader encounters when interpreting the text. As the readers cannot determine what will happen after the terminal, they are actually freed from chopping the text for constructing hopes that will be contradicted by the remaining paragraphs at one point or another, while they have to put down the novel and go on living with the similar situations the novel portrays. Herein resides the hope: externalizing the deadlock of life for the reader, the end of White Noise testifies the ongoing procession of human history that cannot be anticipated beforehand.

Modern technologies coupled with advanced research have allowed model predictive control (MPC) to be applied to new and often experimental systems. The purpose of this research is to develop a model predictive control algorithm for tip-jet reaction drive system. This system's faster dynamics require an extremely short sampling rate, on the order of 20ms, and its slower dynamics require a longer prediction horizon. This coupled with the fact that the tip-jet reaction drive system has multiple control inputs makes the integration of an online MPC algorithm challenging. In order to apply a model predictive control to the system in question, an algorithm is proposed that combines multiplexed inputs and a feasible cooperative MPC algorithm. In the proposed algorithm, it is hypothesized that the computational burden will be reduced from approximately Hp(Nu + Nx)3 to pHp(Nx+1)3 while maintaining control performance similar to that of a centralized MPC algorithm. To capture the performance capability of the proposed controller, a comparison its performance to that of a multivariable proportional-integral (PI) controller and a centralized MPC is executed. The sensitivity of the proposed MPC to various design variables is also explored. In terms of bandwidth, interactions, and disturbance rejection, the proposed MPC was very similar to that of a centralized MPC or PI controller. Additionally in regards to sensitivity to modeling error, there is not a noticeable difference between the two MPC controllers. Although the constraints are handled adequately for the proposed controller, adjustments can be made in the design and sizing process to improve the constraint handling, so that it is more comparable to that of the centralized MPC. Given these observations, the hypothesis of the dissertation has been confirmed. The proposed MPC does in fact reduce computational burden while maintaining close to centralized MPC performance.