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University of Macau / Faculty of Arts and Humanities. / Department of English

University of Macau / Faculty of Arts and Humanities. / Department of English

This thesis describes a study into the performance of both opening and closing switches, as used in pulsed-power networks. It also discusses the important energy storage and compression techniques that are used in the generation of high-energy pulsed power. Various different types of switches are involved in these applications, and particular consideration is paid to the performance of the MESS (Magnetic Energy Switching System) switch, used both in isolation and as part of a pulse-forming network. Exploding wires and foils are also investigated in some detail, since important features from the action of these are present in most opening switches.

Firstly, for a optical switch that suffers from the intrinsic crosstalk problem when two optical signals cross at the same switch element, active connections must be node-disjoint in the switching network to avoid crosstalk. Applying a sequence of decomposition and merge operations, called crosstalk-free conjugate transformation, on each switch element to tackle this problem, the network resulting from this transformation is called crosstalk-free conjugate network. By using the numbering schemes of networks, we prove that if the route assignments in the original network are link-disjoint, their corresponding ones in the conjugate network would be node-disjoint. Thus, traditional nonblocking switching networks can be transformed into crosstalk-free optical switches in a routine manner. / Furthermore, we show that crosstalk-free or wavelength interleaving multicast switches can also be obtained from existing nonblocking multicast switches via the same crosstalk-free or wavelength-interleaving conjugate transformation in a straightforward manner, respectively. / On the other hand, high speed and easy integrated arrayed waveguide gratings (AWGs) and tunable wavelength converters (TWCs) are promising optical devices to construct wavelength division multiplexing (WDM) optical switches. In order to practically realize a WDM switch, the core research issue is how to provide wavelength-interleaving connections throughout the entire switch network of these optical devices. In this way, the topological transformation consisting of decomposition and merge operations can convert nonblocking space-division networks into wavelength-interleaving conjugate networks. The principle of this transformation relies on the parallel characters of internal contentions of space switches and wavelength interferences of WDM switches. We show that any nonblocking route assignments in the original space-division network can be mapped into the conjugate network and become wavelength interleaving under this topological transformation. / The emerging all optical network (AON) calls for the realization of high speed (user data rates from 10 Mbps to 10 Gbps), high capacity (∼NTbps) transparent optical network. One of the major obstacles of AON is the deployment of high-speed optical switching systems that can switch optical signals at the rate of several terabits per second. In all optical switches constructed by different optical devices, the crosstalk or wavelength interference may happen when any two optical signals cross at a single optical device or when two signals carried by the same wavelength in a single link, respectively. In the past serval decades, the nonblocking electronic switching networks have been widely studied and a mature theory has been erected. In this thesis, we propose an easy-to-implement conjugate transformation applied to the traditional nonblocking switching networks in two opposite manners to tackle these two problems, respectively. / Deng Yun. / "January 2007." / Adviser: Tony Tong Lee. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 6176. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 101-108). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

IP address lookup is an important processing function of Internet routers. The challenge lies in finding the longest prefix that matches the packets destination address. One of the issues concerning IP address lookups is the average lookup time. In previous works, caching was shown to be an effective method to minimize the average lookup time. Caching involves storing information on recent IP lookup results in order to decrease average lookup times. In this thesis, we present two architectures that contain a prefix cache and a dynamic substride cache. The dynamic substride cache stores longest possible substrides from previous lookups, and is used in conjunction with a prefix cache. Successful hits in both the caches help reduce the number of worst-case lookups in the low level memory containing the IP routing table in a trie data structure. From simulations, we show that the two architectures show up to 99.9%global hit rate. Furthermore we present analytical models to find optimal designs for the two architectures. We also show that the architectures can support incremental updates once appropriate modifications are made to the trie data structure.

One of the most famous problem of finding optimal weight to maximize an agent's expected terminal utility in finance literature is Merton's optimal portfolio problem. Classic solution to this problem is given by stochastic Hamilton-Jacobi-Bellman Equation where we briefly review it in chapter 1. Similar idea has found many applications in other finance literatures and we will focus on its application to the high-frequency trading using limit orders in this thesis. In [1], major analysis using the constant volatility arithmetic Brownian motion stock price model with exponential utility function is described. We re-analyze the solution of HJB equation in this case using different asymptotic expansion. And then, we extend the model to the regime-switching volatility model to capture the status of market more accurately.

One of the most famous problem of finding optimal weight to maximize an agent's expected terminal utility in finance literature is Merton's optimal portfolio problem. Classic solution to this problem is given by stochastic Hamilton-Jacobi-Bellman Equation where we briefly review it in chapter 1. Similar idea has found many applications in other finance literatures and we will focus on its application to the high-frequency trading using limit orders in this thesis. In [1], major analysis using the constant volatility arithmetic Brownian motion stock price model with exponential utility function is described. We re-analyze the solution of HJB equation in this case using different asymptotic expansion. And then, we extend the model to the regime-switching volatility model to capture the status of market more accurately.

With the increasing demand for multi-media,multi-core system architecture used in parallel processing of large amounts of data to carry out operations,in the past,large amounts of data is transferred through an independent control of DMA,and often have the following shortcomings,(1)As a result of the transmission of data is completed by reading and writing,caused the burden of memory clock singnal,(2)A large number of occupied bandwidth,caused the collision with processor by using the data bus. Based on the above shortcomings, this paper proposed an internal fast data switching mechanism through AMBA instruction by integrating the memory controller and DMA function. With the high transmission clock rate of DDR2, to achieve (1) transfer data by the original memory clock rate between memory and memory, (2) transmission between memory and device can be reached by bridge of the controller. Can significantly reduce not only the System Bus in the workload and provide the purpose of handling large amounts of data, to reduce the transmission of data on the amount of time spent and release of the right to use the Bus to other peripheral devices and to enhance the efficiency of the overall system.We also achieved the interface of SATA bridge in the controller. Through the DDR2 memory buffer to enhance the efficiency of accessing information and to provide strong type on the data buffer mechanism, can effectively reduce the number of solid-state hard disk access, the extension of its work life. According to the simulation results show that the use of traditional DMA transfer mechanism for the rapid exchange of data, compared to provide a minimum bandwidth in DDR2, you can save about 51% of transmission time, in the DDR2 maximum bandwidth available, you can save 87% of transmission time.