An ad hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any fixed network infrastructure or centralized administration. Due to the limitations in the wireless environment, it may be necessary for one mobile host to enlist the aid of other hosts in forwarding a packet to its destination. In order to enable communication within the network, a routing protocol is needed to discover routes between nodes. The primary goal of ad hoc network routing protocols is to establish routes between node pairs so that messages may be delivered reliably and in a timely manner. The basic access method in IEEE 802.11 ad hoc networks is the Distributed Coordination Function (DCF), which provides a fair medium access. Enhanced Distributed Coordination Function (EDCF) has been developed to provide service differentiation among different traffic flows. In this thesis, we investigate the performance of the EDCF with routing protocols / Direct Sequenced Distance Vector (DSDV) and Dynamic Source Routing (DSR) by simulations.

Energy performance in buildings has become one of the most broadly debated subjects in contemporary architecture / and current legislation has emphasized its importance by requiring buildings to possess an energy performance certificate. Due to the technological advances in computational tools, it is possible to analyze the energy performance of buildings before construction starts / however most energy performance evaluation tools, requiring complex solid models and high technical knowledge in the field, can be used only during the post design phases. Since any design decision has an important effect on the energy performance of a building, evaluation tools should be used from the very beginning of the design process. In this dissertation, a building energy performance evaluation program, entitled the Energy performance Advisor (EnAd), was developed for evaluating the energy performance of buildings considering not only the legal framework of Turkey, but also the building design process. The program does not need advanced expertise, and was developed to be usable in any phase of the design process. The program, using the monthly calculation method of TS EN ISO 13790, was developed based on the European Union Directive on Energy Performance in Buildings (EPBD) and the current Turkish legislation on the subject. EnAd integrates the legal framework with the energy performance criterion into the building design process, while providing rapid feedback on energy performance and related legislation, and guiding the designer to improve design decisions. This dissertation has also shown the effects of building size, exposed surfaces, ventilation and infiltration, window-wall ratio, U-values, set-point temperatures and temperature differences between the outside and inside spaces on energy performance of buildings through generic case studies while searching the reasons for discrepancies between the results derived from the four evaluation tools, three of which is highly acknowledged energy performance evaluation tools. The validity, reliability, precision and usability of EnAd as a design-support tool has been proved through the usability and convergence tests conducted. Finally, the thesis has pointed out the importance of the use of energy performance evaluation tools from early stages of architectural design process to achieve higher performances as well as the roles of decision makers in this process.

Data traffic has emerged as a big challenge for the standardization of traffic management mechanisms in ATM networks. In April 1996 the ATM Forum published the first version of the Available Bit Rate Service Category (ABR) to give support to this kind of traffic. ABR was designed with ambitious objectives: high network efficiency, fairness and inter-operability of different ABR switch mechanisms.The major part of this PhD Thesis has been devoted to ABR. Instead of focusing on one aspect of ABR, the main research topics involved in ABR have been covered, namely: (i) switching mechanisms, (ii) conformance definition, (iii) charging, (iv) ABR support to TCP traffic. In the following the main conclusions are summarized. Maybe, switch algorithms have been the most investigated topic of ABR. This has happened because the specification of ABR given by the ATM Forum allows a diversity of switch algorithms to be implemented. These range from the simplest binary switches to the more complex ER switches. In the PhD Thesis three of these switch algorithms are analyzed by means of simulation, showing the different degree of performance and complexity that can be achieved. The behavior of ER switches is also analyzed by means of real traces obtained with a commercial ER switch. The conformance definition is the formalism established to decide whether the source transmits according to the traffic contract. The conformance algorithm standardized for ABR is the Dynamic Generic Cell Rate Algorithm (DGCRA). The PhD Thesis gives a detailed description of the DGCRA. Furthermore, traces obtained by simulation are depicted showing that the algorithm given by the ATM Forum has a decreasing accuracy of the rate conformance with increasing feedback delay. A "UPC based on the CCR" is proposed to solve this drawback. The parameter dimensioning of the DGCRA is addressed in the PhD Thesis by means of two analytical approaches. Numerical results calculated with the analytical models are also obtained by simulation for validation. The analytical approaches are based on a novel queuing model of the DGCRA. The first analytical approach is based on a renewal assumption of the cell inter-arrival process at the UPC. This approach gives a simple but coarse approximation of the cell rejection probability at the UPC. The second analytical method consists of a Markov chain that accurately describes the stochastic variables involved in the queuing model of the DGCRA. The Markov chain is solved applying the matrix geometric technique. The complexity of this mathematical approach only allows investigating a simple network topology. However, the accuracy of the model allows taking into account the influence of the delay bounds that are negotiated with the DGCRA. This study shows that a major degradation of the cell rejection probability may be obtained if these delay bounds are not properly set. Another issue investigated in the PhD Thesis is the charging of ABR. Charging may have a decisive impact on the deployment, success and growth of a network. In fact, the research community has paid a great attention to this topic in recent years. Furthermore, pricing may be an essential condition for the users when submitting traffic. Some authors have used this fact to propose congestion control mechanisms based on a dynamic pricing. In such schemes, prices vary according to the demand of network resources by the sources. New prices are conveyed to the sources by means of a feedback mechanism. This charging scheme seems to fit well with ABR, since the RM-cells can be used to dynamically communicate the prices. In the PhD Thesis a dynamic pricing scheme is proposed and an analytical model is used to find out the evolution of the prices. Additionally, several charging schemes are confronted by simulation. This comparison shows that the dynamic pricing gives the best expected charging. Finally, the support of ABR to the traffic generated with the TCP protocol used in the Internet is investigated by simulation. Currently, the data communications are dominated by the Internet traffic transported by a variety of networks. The deployment of ATM technology has been located in the backbone networks and the end-to-end ATM systems appear remote. In fact, it is not clear whether the universal multi-service network will be built on the Internet rather than the B-ISDN. Simulations performed in the PhD Thesis confront the transport of TCP traffic in different scenarios using ABR and the simpler UBR Service Category. The main conclusion is that ABR can solve the severe fairness problems that can arise using UBR.

Next generation data centres are expected to support both advance resource reservation and on-demand access, but the system performance for such a computing environment has not been well-investigated. A reservation request is characterized by a start time, duration, and resource requirement. Discrete event simulation is used to study the performance characteristics of reservation systems. The basic strategy is to accept a request if resources are available and reject the request otherwise. The performance metrics considered are resource utilization and blocking probability. Results showing the impact of input parameters on these performance metrics are presented. It is found that the resource utilization is quite low. Two strategies that can be used to improve the performance for advance reservation are evaluated. The first strategy allows the start time to be delayed up to some maximum value, while the second allows the possibility of non-uniform resource allocation over the duration of the reservation. Simulation results showing the performance improvements of these two strategies are presented. Resources not used by advance reservation are used to support on-demand access. The performance metrics of interest is the mean response time. Simulation results showing the impact of resource availability and its variation over time on the mean response time are presented. These results provide valuable insights into the performance of systems with time-varying processing capacity. They can also be used to develop guidelines for the non-uniform resource allocation strategy for advance reservation in case the reserved resources are used for interactive access.

The purpose of this research was to investigate the implications of networked public management on the design, implementation, and utilization of federal performance measurement systems. A multiple, instrumental case study of four public health programs funded by CDC and implemented nationally through vertical and horizontal network structures was conducted. Cross-case findings suggest that the networked implementation structures for the four federal-level, public health programs have important implications for the design of the performance measurement systems. Specifically, the performance measurement systems were affected by four consequences of the implementation networks: the political influence of collaborative stakeholders; network variability; dependencies on voluntary, horizontal network partners to achieve outputs and outcomes; and jointly produced outcomes that compromise assigning agency-specific attribution and accountability. While these four factors did not deter the use of performance measurement by any of the programs, all had important consequences for the development and subsequent design of the performance measurement systems, including limiting the choice and types of measures, level of measurement, potential uses of the measures, and resources needed to implement and support the systems.

公務人員考績淘汰機制為考績法修法重點，本研究運用質性研究方法，對公務人員、學者、企業主管及媒體人員進行訪談，藉此瞭解各界對於考績淘汰機制之看法，探討改善的方向與建議。 本研究之改善建議如下： 法制面： 一、 強化考績考核公平性 二、 淘汰條件必須能篩選出不適任之公務人員 三、 強化各項配套措施 四、 保訓會適當提高審查密度 執行面 一、 淘汰機制應重視宣導與溝通 二、 淘汰機制應對相關人員施予專業訓練 三、 逐步漸進改善淘汰機制 / Elimination mechanism is the most important part of Civil Service Performance Evaluation Act. I have interviewed with some civil servants, scholars,executives and journalists about their opinions on elimination mechanism in civil service performance evaluation system hoping to reform the system. The suggestions of research are stated below: A. the dimension of legal formation： 1. To strengthen the fairness of evaluation. 2. To eliminate unqualified civic servants through appropriate competition. 3. To strengthen other systems in order to fit out the goal of Civil Service Performance Evaluation Act. 4. To enhance examination density by Civil Service Protection and Training Commission. B. the dimension of execution： 1. To pay much attention to publicize and communicate the Elimination mechanism. 2. To train relevant staff to realize how to operate the elimination mechanism. 3. To evaluate the elimination mechanism progressively.

Next generation data centres are expected to support both advance resource reservation and on-demand access, but the system performance for such a computing environment has not been well-investigated. A reservation request is characterized by a start time, duration, and resource requirement. Discrete event simulation is used to study the performance characteristics of reservation systems. The basic strategy is to accept a request if resources are available and reject the request otherwise. The performance metrics considered are resource utilization and blocking probability. Results showing the impact of input parameters on these performance metrics are presented. It is found that the resource utilization is quite low. Two strategies that can be used to improve the performance for advance reservation are evaluated. The first strategy allows the start time to be delayed up to some maximum value, while the second allows the possibility of non-uniform resource allocation over the duration of the reservation. Simulation results showing the performance improvements of these two strategies are presented. Resources not used by advance reservation are used to support on-demand access. The performance metrics of interest is the mean response time. Simulation results showing the impact of resource availability and its variation over time on the mean response time are presented. These results provide valuable insights into the performance of systems with time-varying processing capacity. They can also be used to develop guidelines for the non-uniform resource allocation strategy for advance reservation in case the reserved resources are used for interactive access.

The problem of providing Quality of Service (QoS) in the Internet has been an extremely active area of research and various mechanisms have been proposed related to this subject. Developing network applications have requirements such as bounded delay, jitter, minimum bandwidth and maximum loss rate. There is also a need to support large bandwidth networks because of growing link speeds. Previous QoS efforts did not fully satisfy all these needs of future networks but more recent approaches aim to be both scalable and rich in the provision of guaranteed services. Consequently core-stateless systems received much attention in recent years because of their scalability in supporting per-flow QoS. The property of not maintaining any per-flow state in the core routers is known as being core-stateless. In this thesis study, the need for core-stateless network architectures is pointed out and a literature survey about these schemes is carried out. Core-Stateless Guaranteed Fair (CSGF) network architecture, which provides deterministic fairness guarantees in a work-conserving manner, is selected and evaluated. Simulation studies about stateful Virtual Clock (VC) algorithm and CSGF&rsquo / s sub-protocols Core-Stateless Virtual Clock (CSVC), Core-Stateless Guaranteed Throughput (CSGT) and Core-Stateless Guaranteed Fairness (CSGF) are presented. Finally, the deficiencies in fairness of CSGF are demonstrated.

Most of the older reinforced concrete (RC) buildings have columns that are deficient when the current code requirements are considered. Therefore, performance of the columns determines the performance of the structure under the effects of earthquake induced lateral loads. It is recognized that no provision is proposed in TEC2007 to estimate the failure type called flexure-shear. Behavior of columns having probability of failing in flexure-shear failure mode is mostly underestimated by TEC2007 procedures. In addition, failure type classification of columns performed according to the linear and nonlinear procedures of TEC2007 needs to be examined with respect to the test results to cover all failure types including flexure-shear failure in order to lead the engineers develop economical and realistic retrofit solutions. In this study, different methods are explored to obtain reliable estimates for the performance of code deficient shear critical RC columns. Special considerations are given to Axial-Shear-Flexure interaction (ASFI) approach due to its mechanical background. After examination of different approaches, ASFI method with proposed modifications was selected as the most reliable model and lateral load-displacement analyses were performed on a database of shear critical columns. Findings were compared with the estimations of the nonlinear procedure given in Turkish Earthquake Code (TEC2007) for database columns. In addition, drift capacity equations and simplified safe drift capacity equations are proposed in light of statistical studies on the selected column specimens. In the last part of the study, performance evaluation of columns according to nonlinear procedures of FEMA 356, TEC2007, ASCE/SEI 41 update supplement, and EUROCODE 8 were conducted.

The main topic that is researched in this study is: what performative architecture is and its role in the design process and product. In the scope of performative architecture the aim is to focus what a building does rather than what it is and the fact that architecture should have the capability of being adaptable to changing time, conditions and environment. A design problem is taken under consideration and designed from the scope of performative architecture. The design problem is the transformation of the Defence Line around Amsterdam, designing new buildings with the recent technologies as additions to the forts remaining from 1900&rsquo / s. A &ldquo / performative model&rdquo / , which supports design from the conceptual stage until production of scale prototypes is structured by the author for this specific design problem. This performative model is used as a case study for the research of the role of the computational design tools in the design process and product of performative architecture. In addition to the design process, the role of using computer