Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 139-140). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 139-140). Also available on the Internet.

No description available.

In cooperative networked haptic systems, some distributed distant users may decide to leave or join the cooperation while other users continue to manipulate the shared virtual object (SVO). Cooperative haptic systems that support interaction among a variable number of users, called scalable haptic cooperation systems herein, are the focus of this research. In this thesis, we develop distributed control strategies that provide stable and realistic force feedback to a varying number of users manipulating a SVO when connected across a computer network with imperfections (such as limited packet update rate, delay, jitter, and packet-loss). We fi rst propose the average position (AP) scheme to upper bound the effective stiff ness of the SVO coordination and thus, to enhance the stability of the distributed multi-user haptic cooperation. For constant and small communication delays and over power-domain communications, the effectiveness of the proposed AP paradigm is compared with the traditional proportional-derivative (PD) scheme via multi-rate stability and performance analyses supported with experimental verif cations. Next, in a passivity-based approach, the scalability is pursued by implementing the AP scheme over wave-domain communication channels along with passive simulation of the dynamics. By constructing a passive distributed SVO in closed-loop with passive human users and haptic devices, we guarantee the stability of the distributed haptic cooperation system. However, energy leak at joining/leaving instances may compromise the passivity of the SVO. We examine the preservation of passivity of the proposed SVO scheme for such situations. A switching algorithm is then introduced in order to improve the performance of the cooperative haptic system. Experiments in which three users take turn in leaving or joining the cooperation over a network with varying delay and packet-loss will support the theoretical results. / Graduate / 0771 / 0548 / 0537 / 0544 / rrakhsha@uvic.ca

This thesis is concerned with the synthesis of passive networks, motivated by the recent invention of a new mechanical component, the inerter, which establishes a direct analogy between mechanical and electrical networks. We investigate the minimum numbers of inductors, capacitors and resistors required to synthesise a given impedance, with a particular focus on transformerless network synthesis. The conclusions of this thesis are relevant to the design of compact and cost-effective mechanical and electrical networks for a broad range of applications. In Part 1, we unify the Laplace-domain and phasor approach to the analysis of transformerless networks, using the framework of the behavioural approach. We show that the autonomous part of any driving-point trajectory of a transformerless network decays to zero as time passes. We then consider the trajectories of a transformerless network, which describe the permissible currents and voltages in the elements and at the driving-point terminals. We show that the autonomous part of any trajectory of a transformerless network is bounded into the future, but need not decay to zero. We then show that the value of the network's impedance at a particular point in the closed right half plane can be determined by finding a special type of network trajectory. In Part 2, we establish lower bounds on the numbers of inductors and capacitors required to realise a given impedance. These lower bounds are expressed in terms of the extended Cauchy index for the impedance, a property defined in that part. Explicit algebraic conditions are also stated in terms of a Sylvester and a Bezoutian matrix. The lower bounds are generalised to multi-port networks. Also, a connection is established with continued fraction expansions, with implications for network synthesis. In Part 3, we first present four procedures for the realisation of a general impedance with a transformerless network. These include two known procedures, the Bott-Duffin procedure and the Reza-Pantell-Fialkow-Gerst simplification, and two new procedures. We then show that the networks produced by the Bott-Duffin procedure, and one of our new alternatives, contain the least possible number of reactive elements (inductors and capacitors) and resistors, for the realisation of a certain type of impedance (called a biquadratic minimum function), among all series-parallel networks. Moreover, we show that these procedures produce the only series-parallel networks which contain exactly six reactive elements and two resistors and realise a biquadratic minimum function. We further show that the networks produced by the Reza-Pantell-Fialkow-Gerst simplification, and the second of our new alternatives, contain the least possible number of reactive elements and resistors for the realisation of almost all biquadratic minimum functions among the class of transformerless networks. We group the networks obtained by these two procedures into two quartets, and we show that these are the only quartets of transformerless networks which contain exactly five reactive elements and two resistors and realise all of the biquadratic minimum functions. Finally, we investigate the minimum number of reactive elements required to realise certain impedances, of greater complexity than the biquadratic minimum function, with series-parallel networks.

The ability to passivate metallic surfaces under non-UHV conditions is not only of fundamental interests, but also of growing practical importance in catalysis and microelectronics. In this work, the passivation effect of a surface iodine layer on air-exposed Ta for the copper electroless deposition was investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Although the passivation effect was seriously weakened by the prolonged air exposure, iodine passivates the Ta substrate under brief air exposure conditions so that enhanced copper wetting and adhesion are observed on I-passivated Ta relative to the untreated surface.

Human-robot interaction is an important and broad area of study. To achieve success- ful interaction, we have to study human decision making rules. This work investigates human learning rules in games with the presence of intelligent decision makers. Par- ticularly, we analyze human behavior in a congestion game. The game models traffic in a simple scenario where multiple vehicles share two roads. Ten vehicles are con- trolled by the human player, where they decide on how to distribute their vehicles on the two roads. There are hundred simulated players each controlling one vehicle. The game is repeated for many rounds, allowing the players to adapt and formulate a strategy, and after each round, the cost of the roads and visual assistance is shown to the human player. The goal of all players is to minimize the total congestion experienced by the vehicles they control. In order to demonstrate our results, we first built a human player simulator using Fictitious play and Regret Matching algorithms. Then, we showed the passivity property of these algorithms after adjusting the passivity condition to suit discrete time formulation. Next, we conducted the experiment online to allow players to participate. A similar analysis was done on the data collected, to study the passivity of the human decision making rule. We observe different performances with different types of virtual players. However, in all cases, the human decision rule satisfied the passivity condition. This result implies that human behavior can be modeled as passive, and systems can be designed to use these results to influence human behavior and reach desirable outcomes.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23158号 / 工博第4802号 / 新制||工||1751(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 大村 善治, 特定講師 木村 真之 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Asian international students (AIS) are becoming increasingly more populous in American universities each year. While AIS are enrolled in the same required classes as American students, it has been observed that frequent interaction between AIS and American students is rather uncommon. Due to obvious social hesitation between the two groups of students during classroom discussion, the study presented was initiated in order to unveil possible reasons for this social integration dilemma. Social Attractiveness, Perceived Homophily and Attributional Confidence scales were selected in order to determine possible factors contributing to this dilemma. In order to pursue explanations for the dormant socialization between the two groups of students during class, a survey was administered to a convenience sampling of 426 undergraduate students enrolled in upper-level courses at the University of Central Florida. Results indicated that passive classroom behavior was perceived as less socially desirable by American students. In fact, participants determined that students reflecting passive classroom behavior were less socially attractive, less similar, and less predictable than students that demonstrated active classroom behavior. Ethnicity factors did not play a key role in determining social appeal. These findings provide evidence that the social integration dilemma facing AIS and American students has much more to do with perceived social behavior and cultural differences regarding classroom behavior than with racial prejudice or ethnicity factors.