It¡¦s easy to get the complication of shoulder by using the traditional type of driving a wheelchair, and the move speed of a wheelchair is upper with motor-driven, so makes shimmy or slide usually appearing on caster when the wheelchair is steering .On the other hand, the drive mechanism of wheelchair by single-wheel was developed by the members of MEVL at the same time that this paper was written. Because of these reasons above, this paper analyze the type of steering mechanism and the patents of wheelchair¡¦s steering mechanism first, secondly find the fittest steering mechanism type for a wheelchair. Furthermore, this paper also discusses some irregular conditions of a caster and theirs reasons and how to prove them when a wheelchair is steering or moving with high speed by using several simpler mode of mechanics, such as caster shimmy, the slip angle of a caster, and some irregular cases when wheelchair is driven by single wheel. Finally this paper will design a new type steering mechanism for wheelchair by applied the results of research that above-mentioned, this new steering mechanism not only improve the traditional steering mode of a wheelchair, also avoid several irregular condition above occurring in the caster, moreover, it can be enabled or disabled by user anytime. So this paper expects that the performance of a wheelchair will be raised after the new type steering mechanism is designed.

Consumers often have to wait during the process of acquiring and consuming many products and services. These waiting experiences are typically negative and have been known to affect customers¡¦ overall satisfaction with the product or service. To better manage these waiting experiences, many firms have instituted a variety of programs to reduce the actual duration of the wait. However, consumers are influenced by their perceptions of the waiting duration, not the actual one. Therefore, understanding how consumers perceive their waiting time is particularly important in the marketing of service. In this paper, I use laboratory experiment method and examine the impact of mood, distance to the goal state, and filled mechanism on consumers¡¦ perceptions of waiting time and their affective responses. A total of 206 students recruited at the university participated in the study. The results demonstrate that people in a positive mood tend to perceive shorter duration of the wait than those in a negative mood. Further, the distance to the goal state, i.e. the stage at which the delay occurs during the service encounter, has the impacts on consumers¡¦ time perception and affective responses. The delay produced longer time estimates and stronger affective responses at further from the goal state than at closer to the goal state. And filling time resulted in shorter time perception and less negative emotions. However, the relevance to the service of filled mechanism will not affect consumers¡¦ time estimates but only consumers¡¦ positive affective responses. The distance to the goal and different kind of filled mechanism have an interactive effect only on the time perceptions. Moreover, consumers¡¦ involvements toward service and time style have moderating effects. The higher the involvement, the longer the time estimates and the more negative responses. Qualitative subjects perceived longer waiting time, and quantitative ones have more positive affective responses.

Transition metal catalyzed reactions have an important place in synthetic chemistry, but the mechanistic details for many of these reactions remain undetermined. Through a combination of experimentally determined 13C kinetic isotope effects (KIEs) and density functional theory (DFT) calculations, some of these reactions have been investigated. The cyclopropanation of an olefin catalyzed by rhodium (II) tetrabridged complexes has been shown to proceed through an asynchronous, but concerted mechanism. DFT does not provide an accurate transition structure for the reaction of an unstabilized carbenoid with an olefin, but it does predict an early, enthalpically barrierless transition state which is consistent with the reactivity of unstabilized carbenoids. For the case of stabilized carbenoids, the theoretical structures predict the KIEs accurately and a new model is proposed to explain the selectivity observed in Rh2(S-DOSP)4-catalyzed cyclopropanations. The chain-elongation step of atom transfer radical polymerization (ATRP) has been shown to be indistinguishable from that of free radical polymerization (FRP) for the CuBr/2,2??-bipyridine system. While DFT calculations predict an earlier transition state than observed, the calculations suggest that with increasing levels of theory the predicted KIEs come closer to the observed KIEs. A recently proposed [2 + 2] mechanism for the cyclopropenation of alkynes catalyzed by Rh2(OAc)(DPTI)3 has been shown not to be a viable pathway. Rather, the experimental KIEs are predicted well by canonical variational transition state theory employing the conventional mechanism for cyclopropenation via a tetrabridged rhodium carbenoid. DFT calculations also suggest an alternative explanation for the observed enantioselectivity. The 13C KIEs for metal-catalyzed aziridination have been measured for three separate catalytic systems. While the KIEs do not completely define the mechanism, all of the reactions exhibit similar KIEs, implying similar mechanisms. A surprising feature of this system is the presumed nitrene intermediate??s triplet spin state. This complicates the DFT analysis of this system.

Tyrosine hydroxylase (TyrH) catalyzes the pterin-dependent hydroxylation of tyrosine to form dihydroxyphenylalanine. The enzyme requires one atom of ferrous iron for activity. Using deuterated 4-methylphenylalanine substrates, intrinsic primary and secondary isotope effects of 9.6 ± 0.9 and 1.21 ± 0.08 have been determined for benzylic hydroxylation catalyzed by TyrH. The large, normal secondary isotope effect is consistent with a mechanism involving hydrogen atom abstraction to generate a radical intermediate. The similarity of the isotope effects to those measured for benzylic hydroxylation catalyzed by cytochrome P-450 suggests that a high-valent, ferryl-oxo species is the hydroxylating species in TyrH. Uncoupled mutant forms of TyrH have been utilized to unmask isotope effects on steps in the aromatic hydroxylation pathway which also implicate a ferryl-oxo intermediate. Inverse secondary isotope effects were seen when 3,5-2H2-tyrosine was used as a substrate for several mutant enzyme forms. This result is consistent with a direct attack by a ferryl-oxo species on the aromatic ring of tyrosine forming a cationic intermediate. Rapid-freeze quench Mössbauer studies have provided preliminary spectroscopic evidence for an Fe(IV) intermediate in the reaction catalyzed by TyrH. The role of the iron atom in the regulatory mechanism has also been investigated. The iron atom in TyrH, as isolated, is in the ferric form and must be reduced for activity. The iron can be reduced by a number of one-electron reductants including tetrahydrobiopterin, ascorbate, and glutathione; however, it appears that BH4 (kred = 2.8 ± 0.1 mM-1 s-1) is the most likely candidate for reducing the enzyme in vivo. A one-electron transfer would require a pterin radical. Rapid-freeze quench EPR experiments aimed at detecting the intermediate were unsuccessful, suggesting that it decays very rapidly by reducing another equivalent of enzyme. The active Fe(II) form can also become oxidized by oxygen (210 ± 30 M-1 s-1); this increases the affinity of catecholamine inhibitors. Serine 40 can be phosphorylated to relieve the inhibition; however, results with S40E TyrH show phosphorylation does not have an effect on the rate constant for reduction of the enzyme but causes a 40% decrease in the rate constant of oxidation.

The aggregate power of all resources on the Internet is enormous. The Internet can be viewed as a massive virtual organization that holds tremendous amounts of information and resources with different ownerships. However, little is known about how to run this organization efficiently. This dissertation studies the problems of distributed task and resource allocation among self-interested agents in virtual organizations. The developed solutions are not allocation mechanisms that can be imposed by a centralized designer, but decentralized interaction mechanisms that provide incentives to self-interested agents to behave cooperatively. These mechanisms also take computational tractability into consideration due to the inherent complexity of distributed task and resource allocation problems. Targeted allocation mechanisms can achieve global task allocation efficiency in a virtual organization and establish stable resource-sharing communities based on agents’ own decisions about whether or not to behave cooperatively. This high level goal requires solving the following problems: synthetic task allocation, decentralized coalition formation and automated multiparty negotiation. For synthetic task allocation, in which each task needs to be accomplished by a virtual team composed of self-interested agents from different real organizations, my approach is to formalize the synthetic task allocation problem as an algorithmic mechanism design optimization problem. I have developed two approximation mechanisms that I prove are incentive compatible for a synthetic task allocation problem. This dissertation also develops a decentralized coalition formation mechanism, which is based on explicit negotiation among self-interested agents. Each agent makes its own decisions about whether or not to join a candidate coalition. The resulting coalitions are stable in the core in terms of coalition rationality. I have applied this mechanism to form resource sharing coalitions in computational grids and buyer coalitions in electronic markets. The developed negotiation mechanism in the decentralized coalition formation mechanism realizes automated multilateral negotiation among self-interested agents who have symmetric authority (i.e., no mediator exists and agents are peers). In combination, the decentralized allocation mechanisms presented in this dissertation lay a foundation for realizing automated resource management in open and scalable virtual organizations.

Since London Stock Exchange introduced bookbuilding in IPO in 1992, more and more countries also allowed companies to go IPO through bookbuilding or bookbuilding hybrid with other IPO mechanism. About 90% of the countries in the world allow bookbuilding, and it has formed a potential trend. There were about 60% of IPOs using bookbuilding in LSE, and almost 90% of the investors in the market were institutional investors. Under the main board is Alternative Investment Market (AIM) without any listing criteria, companies are qualified for listing just by designating a nominated advisor (NOMAD), and about 40%-50% of the investors on AIM are institutional investors. The growth of AIM were so amazing in recent years, especially, the number of IPOs has maintained above 150 issues per year during past five years, and 90% of them were through bookbuiling. The main purpose of this study is to figure out why companies tend to use bookbuilding. From the evidence of LSE, we found that the smaller company or issue is, the more possible that they would choose bookbuilding. When the market is less liquid, bookbuilding would likely be used, and stocks that sold through bookbuilding are usually less liquid. Companies listed on AIM are usually small and mediun ones, and choosing bookbuiling sometimes signals a good sign about the quality of a company for getting through with the examination from institutional investors. In addition, companies can designated a NOMAD as an underwriter, too. From the view point of maximizing underwriting profit and maintaining the relationship with institutional clients, the underwriter would also tend to use bookbuilding. Besides, we proposed that after-market cumulative abnormal return would be one of the reasons that company chooses bookbuilding, and we found evidence showing after-market cumulative abnormal return under bookbuilding is higher than under offer for subscription.

Abstract The main purpose of this research is to explore the development characteristics, types, functions and operating mechanisms of incubation center in Taiwan and to analyze their relationships. The research processes mainly through case study.And Incubation Center of Taiwan University is selected for data collection and interview because of its outstanding performance. We analyze the operating mechanisms and the current state of our research target.To obtain more objective conclusions, we also interview and collect data from some tenants as comparation. The results and suggestions are as followed: 1.The float rate of the prjoect manager will influence the Incubation Center. 2.Government's relevant policies will influence the operating mechanisms and goals of Incubation Center. 3.The extent the school supports their own Incubation Center will influence the elasticity. 4.The completeness of incubation system will promote the efficiency of Incubation Center. 5.The operating model that Incubation Center, together with Incubation Company, channels into flexible and efficient corporatization management can plurally extend their targets and methods of service. 6.Because of the slow progress of the government¡¦s efforts in revising relevant law, the realistic operation can not be integrated. 7.The operations of the incubation center need to be set up on the basis of cooperartion in the manufacturer, school and incubation center to reach sustainablity.

Epicyclic-type automatic transmissions are widely used in automobiles, it provide different speed ratio by control different elements to be an input or a fixedness with clutches and brakes. There are many researches about the Epicyclic-type automatic transmissions, but the research of the arrangement of clutches and brakes is fewer, and lacked for a method for arranging the desired clutches and brakes quickly. Therefore, the purpose of this research is to develop a methodology for arranging the desired clutches and brakes. First, introduce a planar-graph representation and a number sequence which had been used in arranging desired clutches and brake for years. Second, explore the relationship between contracted graph and epicyclic gear mechanisms based on topology theorem. Then provide a systematical procedure to arrange desired clutches and brakes into epicyclic gear mechanisms. With the above method, can find seven types of feasible clutching sequence that havn¡¦t been discovered in 94 types of feasible clutching sequence. Then, the number of the teeth of all gears can be calculated, as a result, five types of six-speed automatic transmissions are found. Finally, build the model of all the nine-link two-DOF epicylic gear mechanism that can be used in six-speed automatic transmissions.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: MEMS; suspension; gyroscope; folded springs; statics. Includes bibliographical references (p. 182-187).

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 214-223). Available also in a digital version from Dissertation Abstracts.