Several organic reactions that could potentially involve coarctate transition states were investigated by a combination of experimental and theoretical studies. In the thermal fragmentation of ∆-1,3,4-oxadiazolines, the mechanism supported by kinetic isotope effects and theoretical calculations is a three-step process that does not demonstrate any special stabilization in coarctate transition states. Rather than undergoing a direct coarctate conversion to product, the mechanism avoids coarctate steps. The last step is a concerted coarctate reaction, but being concerted may be viewed as being enforced by the necessity to avoid high-energy intermediates. In the deoxygenation of epoxides with dichlorocarbene, the stabilization from the transition state aromaticity is not great enough to compete with the preference for asynchronous bonding changes. KIEs and calculations suggested that the reaction occurs in a concerted manner but with a highly asynchronous early transition state with much more Cα-O bond breaking than Cβ-O bond breaking. In the Shi epoxidation, a large β-olefinic 13C isotope effect and small α-carbon isotope effect indicated an asynchronous transition state with more advanced formation of the C-O bond to the β-olefinic carbon. The calculated lowest-energy transition structures are generally those in which the differential formation of the incipient C-O bonds, the "asynchronicity," resembles that of an unhindered model, and the imposition of greater or less asynchronicity leads to higher barriers. In reactions of cis-disubstituted and terminal alkenes using Shi's oxazolidinone catalyst, the asynchronicity of the epoxidation transition state leads to increased steric interaction with the oxazolidinone when a π-conjugating substituent is distal to the oxazolidinone but decreased steric interaction when the π-conjugating substituent is proximal to the oxazolidinone. Dynamic effects were studied in Diels-Alder reaction between acrolein and methyl vinyl ketone. This reaction yields two products in a ratio of 3.0 ± 0.5. Theoretical studies shows that only one transition structure is involved in the formation of both. Quasiclassical trajectory calculations on an MP2 surface give a prediction of a product ratio of 45:14 (3.2:1), which is in good agreement with the experimental observation.

A recently developed chemical vapor deposition (CVD) synthesis process called CoMoCAT yields single-wall carbon nanotubes (SWCNT)s of controlled diameter and chirality, making them extremely attractive for technological applications. In this dissertation, we use molecular dynamics simulations and density functional theory to study the selective growth mechanisms. In the CoMoCAT process, growth of SWCNTs happens on Co clusters with diameters of about 1 �. Effective force fields for Ni-C interactions developed by Yamaguchi and Maruyama for the formation of metallofullerenes and the reactive empirical bond order Brenner potential for C-C interactions are modified to describe interactions in such system. Classical molecular dynamics (MD) simulations using this force field are carried out to study the growth of SWCNT on floating and supported metal clusters. The effect of metal-cluster interactions on the growth process is discussed. The energy of forming one more ring at the open end of one-end-closed nanotubes with different chiralities, which is believed to be the basic step of nanotube elongation, are studied as a function of tube length. The energy and shape of the frontier highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of armchair nanotubes are studied and used to explain the change of reaction energy with tube length. Another property, the aromaticity of the rings forming a tube is also studied using Nucleus Independent Chemical Shift (NICS) as probe. NICS of rings in one-end-closed nanotubes with different chirality are studied as a function of tube length. NICS behavior of one-end-closed nanotube is compared with that of two-ends-open nanotube with the same chirality for nanotubes (6, 5) and (9, 1). Also (8, 3) nanotubes with one end open and the other end bonded to three different kinds of cap structures are compared. Since from both experimental observation and from our MD simulation results, the growth process of SWCNT can be affected by the interaction between Co clusters and their substrate, the performance of a series of CoN Clusters (N=1-4, 7, 10, 14, 15) adsorbed on MoC surface are studied with density functional theory.

In the traditional login systems, we use the username and the password to identify the legalities of users. It is a simple and convenient way to identify, but passwords could be stolen or copied by someone who tries to invade the system illegally. Adding one protective mechanism to identify users, the way of biometrics are brought out, such as keystroke dynamics, fingerprints, DNA, retinas and so on that are unique characteristics of each individuals, it could be more effective in preventing trespassing. This thesis uses keystroke biometrics as research aspects of user authentication. The advantages of this system are low-cost and high security to identify users using keyboard to calculate the time of keystrokes. In this thesis, we use statistical way to examine the researches and experiments. Chosen length of the username and password are greater than or equal to 9 characters, and learning sample sizes are 20 and adapting the sample adaptation mechanism, the results show that we achieved by False Acceptance Rate of 0.85%, False Rejection Rate of 1.51% and Average False Rate of 1.18%; all reach the high levels of safeties.

This paper studies the relation between the optimal capital structure and industry dynamic. First,we formulate a dynamic adjustment model. We specify and estimate the unobservable optimal capital structure using observable determinants Secondly,we apply dynamic factor demand model that assumes each firm derives an optimal plan such that the expected present value of current and future cost streams is minimized. In variables setting, capital inputs are divided into debt capital and equity capital. The empirical work is based on firm level data of Taiwan high-technology industries during 2003 ~2007. The empirical results show that (1) The capital structure of high- technology is adjusted dynamaic.(2) The contribution of debt on high-technology industries is negative.

In this study, Gordon Schaefer Model is used to evaluate for the optimal conduction of open access and dynamic optimization in equilibrium condition. The results of the models are further analyzed by the method of comparative static analysis. According to the Schnute's method, the intrinsic growth rate, the catchability coefficient and the environmental carrying capacity have been estimated in the way to evaluate the equilibrium values of the resource stock and the effort of yellowfin tuna. The result of the sensitivity analysis is based on the assumption that all parameters are varied within reasonable ranges. The results of comparative static analysis consist with the results of the sensitivity analysis that the fishing is comparatively cohered with the dynamic optimization model. This study aims to provide a useful reference for the policy making in sustainable development of the offshore fishery resources in Taiwan.

The diffusion of the Internet is the interest of many firms or individuals who see the Internet as an opportunity, a threat, or both. Huge amount of intellectual and real capital are invested on Internet. The more people understand the dynamics of Internet diffusion, the better they will manage the efforts put on it. The purpose of this study is to explore the extent to which the diffusion of the Internet-related innovation could be adequately described by the diffusion models and the effect of internal influence versus external influence described in the models. Two hypotheses of the Internet innovation diffusion are proposed. First, the number of potential adopters of the Internet innovation diffusion is dynamic, not constant. Second, in contrast to the traditional innovations, the diffusion of Internet innovation has stronger interpersonal communication influence than the promotional activity effect. Twelve Internet innovations are estimated in both the Bass model and the Dynamic model. The first hypothesis is fully supported, and the second hypothesis is partially supported. Based on the evidence, Internet innovations can be categorized into web-based versus non-web. The non-web Internet innovation of connection and communication like Internet, ADSL, and Skype has no significant difference of the ratio of the internal influence and the external influence effects to the traditional innovations. The segment-focused niche website, such as Amazon, eBay, and PayPal, has the strong internal influence effect. Understanding the various effects of Internet innovation diffusion can provide advantages in terms of enhancing functions and planning marketing strategies and tactics.

In login systems, a user is asked to enter his correct account and password in order to be allowed to enter to the system. The safety of systems is at the risk of leaking out the information, hence, the single mechanism of identity verification has not filled the bill at present. We study the personal typing behavior to get one¡¦s own specific features. In our thesis , we compare three methods and anlysis the advantages and shortcomings of those three. First one is to sort the twenty study data, and distribute the weights into the proper region. If the total weights is less than the threshold then this test data will be accepted, otherwise, it will be rejected. The second and third method are similar. Both of them are trying to rescale the data. The spirit of them is that the typing rate of a person will be faster when they type frequently and will be sloer when they are out of practice. However the relative positions of those keys, the lengths of ons¡¦s fingers, and the time that people making pauses in reading unpunctuated are unique. Those factors can be one¡¦s typing rhythm. There are twenty two individuals involved in this experiment. Each one choose his own proficient account and password to type and set up his typing model. The imposters are randomly choose legal user to imitate.

Abstract At present, most of the enterprises make use of a set of software system of Enterprise Resource Planning (ERP) in order to improve the internal management, and regards it as the nuclear information system. Their goal is to promote the enterprise's operational benefits (Hong and Kim, 2002) by the synthetic effects. Some enterprises induct do brings certain benefits after using the EPR. However, faces the current violent and competitive environment, the majority of ERP are not able to arrange the uses of resources effectively, which causes the enterprises unable to make the delivery dates of the customers¡¦ orders punctually or causes the enterprises¡¦ original profits reduced due to storing up too much stock for satisfy the delivery dates of the customers¡¦ orders. This research take a T Corporation, one of small and medium manufactures of Taiwan, as an example, this company uses the domestic well-known brand system of ERP as the main information system of the enterprise. After using the producing and managing module of ERP to plan its purchase policy of raw materials for a long time, the material inventory stay at a high level even after several years¡¦ adjustment. In addition, due to the price of copper fluctuated heavily frequently in recent years, not only the inventory cost can¡¦t be controlled well but also the orders are missed usually involving being unable to reflect the cost of raw materials on the customers¡¦ quotes immediately. Therefore, this research takes the System Dynamics which is good at solving the problems of dynamic complexity as a simulated research to practice the models¡¦ constructions and simulations and add the prosperity of system thinking into the business strategy to provides the quantifiable analogue result in order to strengthen the insufficient aspects of products and materials of EPR and to assist the enterprises¡¦ boss to solve those problems of dynamic complexity which are easily been neglect when makes operational strategies.

Web services are becoming the dominant way to provide access to on-line information. Web services have a lot of applications, like e-mail, web search engine, auction network and internet banking. On the web services, web application technology and dynamic webpage technology are very important, but hackers take advantage of web application vulnerabilities and dynamic webpage technology to inject malicious codes into webpages. However, a part of the web sites have neglected the issue of security. In this paper, we propose a novel approach for detecting malicious webpages by URL features, anomaly semantics, potential dangerous tags and tag attributes. This research proposed approach mainly consists of three parts: (1) scripting language and automatic link filter. (2) malicious feature. (3) scoring mechanism. By first part, this step can filter out normal webpages to increae detection speed. Second part can identify some known malicious attacks. Third part can search some unknown malicious webpages by scoring. Our experimental results show that the proposed approach achieves low false positive rate and low false negative rate.

In recent years, road navigational devices equipped with GPS technologies are becoming more and more popular. These devices can facilitate drivers to guide the way to reach their destinations. In this Thesis, we propose a dynamic route navigational algorithm (DNA) that can be combined with GPS, electronic map system, and wireless technologies (such as DSRC, VANET, 802.11p, WLAN, WiMAX ..., etc.). By calculating metric from road type, road length, average distance, and average speed of each available candidate road, DNA generates road score table and choose the route with the highest score among candidate routes to reach destination. Additionally, in DNA, a Dynamic Block re-Broadcasting (DBB) scheme is designed to carry out Road-Request message (R-REQ) rebroadcast function. The R-REQ rebroadcast function provides two advantages: (i) It can broadcast R-REQ to a specific coverage area with least hop counts; (ii) It can reduce the number of R-REQ broadcast packets significantly. Although DNA takes more processing time than other navigational algorithms, it can greatly reduce the traveling time by determining the best route to destination. For the purpose of performance evaluation, we develop a simulator by using C++ programming language to compare the performance of DNA with other navigational algorithms. Simulation results have shown that DNA performs much better than other navigational algorithms in reaching destination with shorter travel distance and shorter traveling time.