The information era has brought upon us waves of change that brings affordable technology Within the reach of the average person. Computers connected to the Internet, part of our daily living, have led to the formation of online communities. In the spirit of communal efforts, a community cannot be controlled or managed into a specific form or direction. A community has a need to concentrate its efforts towards a common goal or vision, therefore sufficiently nonrestrictive infrastructure is needed to enable the community members to contribute towards their goal. We design and build infrastructure to support a virtual community, according to the needs of the community. Community members can easily locate and exchange files among each other, interact in private and public chat rooms by means of instant text messages, as well as make announcements and participate in group discussions in a Web based environment. Additional needs are identified and tended to by means of various value adding services. We also formulate a management strategy to lead the community towards self-sustenance / Thesis (M. Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2009.

The information era has brought upon us waves of change that brings affordable technology Within the reach of the average person. Computers connected to the Internet, part of our daily living, have led to the formation of online communities. In the spirit of communal efforts, a community cannot be controlled or managed into a specific form or direction. A community has a need to concentrate its efforts towards a common goal or vision, therefore sufficiently nonrestrictive infrastructure is needed to enable the community members to contribute towards their goal. We design and build infrastructure to support a virtual community, according to the needs of the community. Community members can easily locate and exchange files among each other, interact in private and public chat rooms by means of instant text messages, as well as make announcements and participate in group discussions in a Web based environment. Additional needs are identified and tended to by means of various value adding services. We also formulate a management strategy to lead the community towards self-sustenance / Thesis (M. Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2009.

ABSTRACT DESIGN OF A CONNECTED PIPE TEST FACILITY FOR RAMJET APPLICATIONS SARISIN, Mustafa Nevzat M.S., Department of Mechanical Engineering Supervisor: Asst. Prof. Dr. Abdullah ULAS Co-Supervisor: Prof. Dr. Kahraman ALBAYRAK April 2005, 164 pages Development of the combustor of a ramjet can be achieved by connected pipe testing. Connected pipe testing is selected for combustor testing because pressure, temperature, Mach number, air mass flow rate can be simulated by this type of testing. Real time trajectory conditions and transition from rocket motor (booster) to ramjet operation can also be tested. The biggest advantage of connected pipe testing is the low operation cost and simplicity. Air mass flow rate requirement is less than the others which requires less air storage space and some components like supersonic nozzle and ejector system is not necessary. In this thesis, design of a connected pipe test facility is implemented. Three main systems are analyzed / air storage system, air heater system and test stand. Design of air storage system includes the design of pressure vessel and pressure &amp / flow regulation system. Pressure and flow regulation system is needed to obtain the actual flow properties that the combustor is exposed to during missile flight. Alternatives for pressure and air mass flow rate regulation are considered in this study. Air storage system designed in this thesis is 27.8 m3 at 50 bar which allows a test duration of 200 seconds at an average mass flow rate of 3 kg/s. Air heater system is utilized to heat the air to simulate the aerodynamic heating of the inlet. Several different combustion chamber configurations with different flame holding mechanisms are studied. The most efficient configuration is selected for this study. Combustion analysis of the air heater is performed by FLUENT CFD Code. Combustion process and air heater designs are validated using experimental data. Designed air heater system is capable of supplying air at a temperature range of 400-1000 K and mass flow rate range of 1.5-8 kg/s at Mach numbers between 0.1-0.5 and pressure between 2-8 bar. Finally the design of the test stand and ramjet combustor analysis are completed. 3D CAD models of the test stand are generated. Ramjet combustor that will be tested in the test setup is modeled and combustion analysis is performed by FLUENT CFD Code. The ramjet engine cruise altitude is 16 km and cruise Mach number is 3.5. Key-words: Air Breathing Engines, Ramjet, Connected Pipe, Direct Connect, Vitiator.

We study Social Groups consisting of self-interested inter-connected nodes looking for common content. We can observe Social Groups in various socio-technological networks, such as Cellular Network assisted Device-to-Device communications, Cloud assisted Peer-to-Peer Networks, hybrid Peer-to-Peer Content Distribution Networks and Direct Connect Networks. Each node wants to acquire a universe of segments at least cost. Nodes can either access an expensive link to the content distributor for downloading data segments, or use the well-connected low cost inter-node network for exchanging segments among themselves. Activation of an inter-node link requires cooperation among the participating nodes and reduces the cost of downloading for the nodes. However, due to uploading costs, Non-Reciprocating Nodes are reluctant to upload segments, in spite of their interest in downloading segments from others. We define the Give-and-Take (GT) criterion, which prohibits non-reciprocating behaviour in Social Groups for all nodes at all instants. In the “Full Exchange” case studied, two nodes can exchange copies of their entire segment sets, if each node gains at least one new segment from the other. Incorporating the GT criterion in the Social Group, we study the problem of downloading the universe at least cost, from the perspective of a new node having no data segments. We analyze this NP-hard problem, and propose algorithms for choosing the initial segments to be downloaded from the content distributor and the sequence of nodes for exchange. We compare the performance of these algorithms with a few existing P2P downloading strategies in terms of cost and running time. In the second problem, we attempt to reduce the load on the content distributor by choosing a schedule of inter-node link activations such that the number of nodes with the universe is maximized. Link activation decisions are taken by a central entity, the facilitator, for achieving the social optimum. We present the asymptotically optimal Randomized algorithm. We also present other algorithms, such as the Greedy Links algorithm and the Polygon algorithm, which are optimal under special scenarios of interest. We compare the performances of all proposed algorithms with the optimal value of the objective. We observe that computationally intensive algorithms exhibit better performance. Further, we consider the problem of decentralized scheduling of links. The decisions of link activations are made by the participating nodes in a distributed manner. While conforming to the GT criterion for inter-node exchanges, each node's objective is to maximize its utility. Each node tries to find a pairing partner by preferentially exploring nodes for link formation. Unpaired nodes choose to download a segment using the expensive link with Segment Aggressiveness Probability (SAP). We present linear complexity decentralized algorithms for nodes to choose their best strategy. We present a decentralized randomized algorithm that works in the absence of the facilitator and performs close to optimal for large number of nodes. We define the Price of Choice to benchmark performance of Social Groups (consisting of non-aggressive nodes) with the optimal. We evaluate the performance of various algorithms and characterize the behavioural regime that will yield best results for node and Social Group as well.