So Kin Tai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 65-66). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The 0-1 sorter and concentrator --- p.1 / Chapter 1.2 --- Review of literature on constructions --- p.3 / Chapter 1.2.1 --- Odd-even merging network --- p.4 / Chapter 1.2.2 --- The Fast Knockout algorithm --- p.5 / Chapter 1.2.3 --- Reverse Banyan network prepended by running sum adder --- p.10 / Chapter 1.2.4 --- Recursive construction using iterative cells --- p.14 / Chapter 1.2.5 --- Comparison of construction algorithms --- p.17 / Chapter Chapter 2 --- Compressor based on baseline-swap network --- p.22 / Chapter 2.1 --- Bit permutation induced exchange --- p.22 / Chapter 2.2 --- Compressor --- p.26 / Chapter 2.3 --- The baseline-swap network --- p.28 / Chapter 2.4 --- New algorithm for running parity initialization --- p.31 / Chapter 2.5 --- Input fairness --- p.42 / Chapter Chapter 3 --- The general architecture of 0-1 sorter --- p.46 / Chapter 3.1 --- Recursive 2X-construction --- p.46 / Chapter 3.2 --- Control a 2X-interconnection network as a cyclic 0-1 sorter --- p.50 / Chapter 3.3 --- Recursive construction of larger 0-1 sorter --- p.56 / Chapter Chapter 4 --- Epilogue --- p.59 / Chapter 4.1 --- Directions of further studies --- p.59 / Chapter 4.1.1 --- Synchronization within the same stage --- p.59 / Chapter 4.1.2 --- Layout complexity --- p.60 / Chapter 4.1.3 --- Statistical initialization of running parity --- p.62 / Chapter 4.2 --- Conclusion --- p.63 / REFERENCES --- p.65

During this PhD study, metamaterials incorporating active devices such as varactors and non-Foster circuits, were researched and designed. Starting from the research on tuneable metamaterials, an electronically controlled leaky-wave (LW) antenna based on composite right/left handed (CRLH) transmission line (TL) structure was proposed which could perform a broadband beam-fixing function with the frequency range from 1 to 4 GHz. In addition, scanning from forward to backward at a fixed frequency can be achieved by manipulating the biasing voltage applied to the varactors. Most of this study has been devoted to the non-Foster active metamaterials. First, the characterization of active magnetic metamaterials with non-Foster loads was presented. Based on the equivalent circuit model, stability of an actively-loaded loop array was examined through different analysis techniques, further to give the design specifications to achieve the broadband non-dispersive negative-Re(μ) (MNG) or μ-near-zero (MNZ) magnetic properties. Moreover, the wave propagation in the actively-loaded medium was investigated. By relating the dispersion characteristics and the effective medium properties, we henceforth proposed the design of zero-loss and broadband metamaterials. This thesis also has covered the study of active high impedance surfaces (HIS) with non-Foster loads. As a two-dimensional metamaterial structure, HIS have been widely used in the microwave and antenna engineering. However it can be easily seen that the performance of a general passive HIS is always limited by the narrow bandwidth, thus making a broadband HIS desirable. In this work, an analytical solution to achieving a stable broadband HIS structure is given by incorporating appropriate negative impedance converter (NIC) circuits. Simulation results have verified the design approach. Finally, the design of NIC circuits was presented as the key part of the realization of active metamaterials. Two schemes have been adopted to realize the design of NICs, one is the operational amplifier (op-amp) based NIC, and another is based on discrete transistors. Both types of NICs were introduced and studied in this thesis.

Ngai Li. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 75-[78]). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The purpose of my diploma thesis is to determine whether regulation of fixed access electronic communications networks, as defined by the European regulatory framework, leads in Czech market to its objectives to be reached and possibly discuss the reasons for failure. For this purpose diploma thesis analyzed the development of two relevant markets focusing on competition in fixed telecommunications services. The work shows that the purpose of regulation is not completely filled, because there is no reduction in market share of incumbent at both markets. However, it is only because of settings of regulation. However, from the perspective of the end customer, competitive market exists. Author in the end proposes own solution to the problem in the form of deregulation of access obligation.

Since the progressive era, American cities have generally expanded their authority in policymaking and service provision. State governments have at times acted to preempt city authority on particular points of policy, but it is unclear whether the threat of this action inspires caution in the decision making of city leaders. The results of an experimental survey distributed to elected city officials across the United States show that a perceived threat of preemption does not significantly discourage city leaders in supporting a proposed broadband internet service provision. These results suggest that political pressure in the form of preemption is not persuasive to city leaders, and that local representational interests are likely more influential on municipal government.

A structured organisation of tasks, possibly hierarchical, is necessary in a BISDN network due to the complexity of the system, its large dimension and its physical distribution in space. Feedback (possibly supplemented by feedforward) control has an essential role in the effective and efficient control of BISDN. Additionally, due to the nonstationarity of the network and its complexity, a number of different (dynamic) modelling techniques are required at each level of the hierarchy. Also, to increase the efficiency of the network and allow flexibility in the control actions (by extending the control horizon) the (dynamic) tradeoff between service-rate, buffer-space, cell-delay and cell-loss must be exploited. In this thesis we take account of the above and solve three essential control problems, required for the effective control of BISDN. These solutions are suitable for both stationary and nonstationary conditions. Also, they are suitable for implementation in a decentralised coordinated form, that can form a part of a hierarchical organisation of control tasks. Thus, the control schemes aim for global solutions, yet they are not limited by the propagation delay, which can be high in comparison to the dynamics of the controlled events. Specifically, novel control approaches to the problems of Connection Admission Control (CAC), flow control and service-rate control are developed. We make use of adaptive feedback and adaptive feedforward control methodologies to solve the combined CAC and flow control problem. Using a novel control concept, based on only two groups of traffic (the controllable and uncontrollable group) we formulate a problem aimed at high (unity) utilisation of resources while maintaining quality of service at prescribed levels. Using certain assumptions we have proven that in the long term the regulator is stable and that it converges to zero regulation error. Bounds on operating conditions are also derived, and using simulation we show that high utilisation can be achieved as suggested by the theory, together with robustness for unforeseen traffic connections and disconnections. Even with such a high efficiency and strong properties on the quality of service provided, the only traffic descriptor required from the user is that of the peak rate of the uncontrollable traffic. A novel scheme for the dynamic control of service-rate is formulated, using feedback from the network queues. We use a unified dynamic fluid flow equation to describe the virtual path (VP) and hence formulate two illustrative examples for the control of service-rate (at the VP level). One is a nonlinear optimal multilevel implementation, that features a coordinated decentralised solution. The other is a single level implementation that turns out to be computationally complex. Therefore, for the single level implementation the costate equilibrium solution is also derived. For the optimal policies derived, we discuss their implementation complexity and provide implementable solutions. Their performance is evaluated using simulation. Additionally, using an ad hoc approach we have extended previous published works on the decentralised coordinated control of large scale nonlinear systems to also deal with time-delayed systems.

ATM is based on the efforts of the ITU-T Broadband Integrated Services Digital Network (B-ISDN) standard. It was originally conceived as a high-speed transfer technology for voice, video, and data over public networks. The ATM Forum has broadened the ITU-T�s vision of ATM for extended use over public and private networks, multi-protocol support and mobile ATM. There are also some ATM applications in High Performance Computing (HPC). ATM is a packet switching technique based on a virtual circuit mechanism. Data flows are statistically multiplexed and communication resources are dynamically shared. Therefore the high performance ATM switch is essential for quality of services (QoS). This thesis introduces typical ATM switch architecture design and analyses design problems. The research objective is to propose a switch architecture design that can solve or improve those existing problems to achieve a superior performance. The research goal is an integrated ATM switch architecture that will handle both unicast and multicast packets. Unlike the usual design for the multicast ATM switch which concentrates on a cell copy network with a unicast switching network, the proposed switch architecture processes the network packets in a single switching block, and allows unicast and multicast packets to co-exist without competing. The switch design has a simple topology and operation principle and is easy to implement. Furthermore, no copy network is required. Three major components are proposed to form the core of the new switch architecture: the parallel buffering strategy for improved buffer performance, the fast table lookup algorithm for packet duplication and routing, and the relay ring controller for solving the contention problem associated with multiple packets destined for the same output port. A mathematical model is presented and its numerical results are analysed. In addition, the simulation algorithms for the proposed switching design are presented and compared against the switching design with input and output buffering strategies. The simulation results are also compared and analysed against the numerical results. A multicast traffic model is also presented. Its performance calculation for the proposed switch is achieved through simulation. Performance analysis is compared against the output buffering switch under the same multicast traffic model. The performance analysis shows that the proposed switch architecture achieves high throughput with low cell loss rate and low time delay. Its performance can be as good as the output buffering strategy or better. Therefore the proposed switch design has solved the problems associated with input and output buffering. This thesis also analyses the complexity of the proposed switch architecture and suggests a topology to build a large scale ATM switch. The suitability and feasibility for production implementation are also addressed.

The use of the microstrip antenna has grown rapidly for the last two decades, because of the increasing demand for a low profile antenna with small size, low cost, and high performance over a large spectrum of frequencies. However, despite the advantages microstrip antennas provide, a number of technical challenges remain to be solved for microstrip antennas to reach their full potential, particularly if they are to be interfaced with monolithic circuits. The objective of this thesis is to examine novel methods for integrating and constructing broadband microstrip antennas, particularly at high microwave and millimeter wave frequencies where dimensions get very small and fabrication tolerances are critical. The first stage of the thesis investigates techniques to reduce the spurious feed radiation and surface wave generation from edge-fed patch antennas. A technique to reduce the spurious radiation from the edge-fed patch antenna by using a dielectric filled cavity behind the radiating element is explored. From this, a single element edge-fed cavity backed patch antenna was developed. Measured results showed low levels of cross polarization, making it suitable for dual or circular polarization applications. A 2 x 2 edge-fed cavity backed patch antenna array was also developed, which benefited greatly from this new technique due to the extensive feed network required. Furthermore, investigation into edge-fed cavity backed patches on high dielectric materials was also conducted. The measured impedance bandwidth of this edge-fed cavity backed patch is three times greater than the conventional edge-fed patch, and the gain increases to 5.1 dBi compared to 3.6 dBi. Further bandwidth enhancement of the single element edge-fed cavity backed antenna on high dielectric material was achieved by applying the hi-lo substrate structure. The hi-lo substrate structure produced an increase in the bandwidth to 26% from the 1.7% of the single element edge-fed cavity backed patch, while maintaining pattern integrity and radiation efficiency. Next, the development of a flip-chip bonding technique was investigated to enhance the fabrication accuracy and robustness of multilayer antennas on high dielectric materials. This technique was proven through simulation and experiment to provide good impedance and radiation performance via the high accuracy placement of the superstrate layer. The single element flip-chip patch antenna uses a high dielectric constant material for both the base and the patch superstrate, whereas the stacked flip-chip patch again uses a high and low permittivity material combination to achieve efficient wideband performance. Due to the high permittivity feed material, these antennas display the attributes required for integration with MMICs. The measured 10 dB return loss bandwidth of the single element was 4% with a gain of 4.6 dBi, whereas the stacked flip-chip patch showed very broadband performance, with a bandwidth of 23% with a gain of 8.5 dBi. The high accuracy placement and rigid attachment of the upper superstrat e layer via the flip-chip bonding technique also enables these antennas to be scaled up to millimeter-wave operational frequencies. The final section of this thesis is focused on developing a fabrication technique to enable the creation of a low permittivity layer at a nominated thickness.

Outpatient consultations form a large part of the healthcare of patients at tertiary hospitals, both as a precursor to in-patient treatment and for the management of on-going health conditions or long-term rehabilitation and monitoring after treatment. These outpatient consultations are generally conducted at the hospitals, most often located in large cities. Patients who live outside these cities face extensive travel to attend these consultations, placing a burden on themselves and on their families or carers. An ability of a tertiary hospital to deliver outpatient consultations in a telehealth mode to regional or remote locations closer to the patients’ homes would potentially relieve much of this burden of travel. Tertiary healthcare is highly complex. It can involve multiple clinicians, can require long time periods for its completion and often includes the patients and their families in the management of the healthcare situation. Outpatient consultations typically involve high levels of interpersonal discussion supported by access to data about the patient. Telehealth methods of delivering these outpatient consultations will be very demanding on the network connection between hospital and remote telehealth nodes. The next generation of Internet or intranet, often referred to as “broadband”, will have the capacity to deliver multiple high-quality, low-latency video streams and to provide shared access to large data sets. The prospective match of the capabilities of broadband networks and the needs of tertiary-level telehealth opens the possibility of effective, tertiary-level outpatient consultations in a telehealth mode of delivery. In this thesis I use a case-study-based approach to evaluate the development and pilot trial of a broadband telehealth system in a tertiary paediatric context. I use the data from these case studies to explore the way that a human-centred approach can be used to evaluate outpatient telehealth trials at a tertiary level of healthcare. My results show that human-centred evaluation for this level of telehealth must take a broad approach; that the telehealth activities must take place in a realistic setting; that qualitative and quantitative responses from participants must be complemented by observational data; that data must be gathered from all the participants; and that their competence to give meaningful responses must be recognised and their multiple, and possibly differing, points of view must be taken into account. Finally, my results show that the researchers must take into account the wider clinical and hospital contexts and in particular the participants’ view of these contexts, when interpreting evaluation data. My overall prediction is that telehealth applications for tertiary-level outpatient consultations will have important, transient phases in their development, and that a human-centred evaluation approach is the appropriate way to evaluate telehealth applications during these phases. These transient phases are not reported in conventional telehealth literature but my analysis of my case studies suggests that they are central to this class of tertiary level telehealth delivery.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.