This research proposes a methodology to solve distributed optimization problems where quasi-autonomous decision entities directly interact with each other for partial information sharing. In the distributed system we study the quasi-autonomy arising from the assumption that each decision entity has complete and unique responsibility for a subset of decision variables. However, when solving a decision problem locally, consideration is given to how the local decisions affect overall system performance such that close-to-optimal solutions are obtained among all participating decision entities. Partial information sharing refers to the fact that no entity has the complete information access needed to solve the optimization problem globally. This condition hinders the direct application of traditional optimization solution methods. In this research, it is further assumed that direct interaction among the decision entities is allowed. This compensates for the lack of complete information access with the interactive exchange of non-private information. The methodology is tested in different application contexts: manufacturing capacity allocation, single machine scheduling, and jobshop scheduling. The experimental results show that the proposed method generates close-to optimal solutions in the tested problem settings.

In this thesis, we first propose a modified version of the CDPthread to eliminate the restriction on the number of execution engines supported¡Xby dynamically instead of statically allocating the execution engines to a process. Then, we describe a method to balance the workload among nodes under the control of the modified CDPthread to improve its performance. The proposed method keeps track of the workload of each node and decides to which node the next job is to be assigned. More precisely, the number of jobs assigned to each node is proportional to, but not limited to, the number of cores in each node. Our experimental results show that with a small loss of performance compared to the original CDPthread, which uses a static method for allocating the execution engines to a process, the modified CDPthread with load balancing outperforms the modified CDPthread without load balancing by about 25 to 45 percent in terms of the computation time. Moreover, the modified CDPthread can now handle as many threads as necessary.

Botnet is a combination of Cyber Attack, infection, and dissemination. Cross the Internet, the infected hosts might launch DDoS (Distributed Denial-of-Service) Attack, become a proxy sending SPAM according to commands from botmasters via some public services such as IRC, P2P or Web (HTTP) protocol. Among these command and control channel, Web-based Botnet is much difficult to detect because the command and control messages of Web-based Botnet are spread through HTTP protocol and hide behind normal Flows. In this research, we focus on analysis and detection of Web-based Botnet, detection by features - Timeslot, calculation of NetFlow, B2S(Bot to Server) and S2B(Server to Bot) of Web-based Botnet. The experimental result shows the proposed approach which uses the features mention above is good in many different topology designs. In addition, we also got nice detection rate in real network design.

Indian Institute of Science / This dissertation discusses the principles, techniques and approaches adopted in the design of task scheduling algorithms for Distributed Parallel Processing Computer Systems (DPCSs) connected with network of front-end systems (FSs), The primary goal in the design of scheduling algorithms is to minimise the total turnaround time of the jobs to be scheduled by maximizing the utilisation of the resources of the DPCS with minimum data communication overhead, The users present their jobs to be scheduled at the FS, The FS receives a job and generates a finite set of independent tasks based on mutually independent sections having inherent parallelism, Each task could be scheduled to different available processors of DPCS for concurrent execution, The tasks are of three groups viz,, compute intensive tasks, input. output intensive tasks and the combination of compute and input-output intensive tasks. They may have the execution time almost the same. Some of the tasks may have the execution time larger due to precedence constraints than that of other tasks and they are provided with logical breakpoints which can be utilised to further break the tasks into subtasks during scheduling, The technique of using breakpoint of the tasks is more appropriate when the number of available processors is more than the number of tasks to be scheduled. The tasks of a job thus generated are sent to the front-end processor (FEP or the host processor) of the DPCS in the form of data flow graph (DFG), The DFG is used to model the tasks and represent the precedence (or data dependencies) among the tasks, In order to preserve the constraints among the tasks during scheduling and realise efficient utilisation of the resources of DPCS, the DFG is structured in the form of levels, The FBP of DPCS has a resident Task Manager (TM). The key function of the TM is to schedule the tasks to the appropriate processors of DPCS either statically or dynamically based on the required resources. To realise efficient scheduling and utilisation of the processors of DPCS, the TM uses a set of buffers known as Task Forwarding Buffer (TFB), Task Output Buffer (TOB) and Task Status Buffer (TSB) maintained by the FEP of DPCS. The tasks of a job from the FS are received at the TFB. The TM picks up a set of tasks pertaining to a level for scheduling into a temporary buffer C and obtains the status of the processors of DPCS. In order to realise both static and dynamic approaches of allocation, task to processor relation is considered in the scheduling algorithm. If the number of tasks in C is equal to or greater than the number of processors available, one task per processor is allocated, the remaining tasks of C are scheduled subsequently as and when the processors become available. This method of allocation is called static approach. If the number of tasks in C is less than the number of processors available, the TM makes use of the logical breakpoints of the tasks to generate subtasks equal to the number of available processors. Each subtask is scheduled to a processor. This method of scheduling is called the dynamic approach. In all the case the precedence constraints among the tasks are preserved by scheduling the successor task to the parent processor or near neighbouring processor, maintaining minimum data communication between them. Various examples of Computational Fluid Dynamics problems' were tested and the objective of reduced total turnaround time and maximum utilisation of the processors was achieved. The total turnaround time achieved for different jobs varies between 51% and 86% with static approach and 16% and 89% with dynamic approach. The utilisation of the processors varies between the 50% and 92.5%. Hence a speed-up of 5 to 8 folds is realised.

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<p>This paper will expose the serious phenonomen Distributed Denial of Service (DDoS). Businesses without a good security policy are easy targets for attackers. We will cover why its hard to protect yourself, present previous attacks and ways for individuals and businesses to secure themselves. We have based our paper on previous cases and done intervjues with companies who specialize in dealing with these kind of threats. Then come up with guidelines wich will be helpful for businesses when they want to strengthen there security against Distributed Denial of Service-attacks.</p> / <p>Detta arbete upplyser om hur allvarligt fenomenet Distributed Denial of Service (DDoS) är. Företag utan ett väl fungerande säkerhetstänkande kan råka riktigt illa ut vid en DDoS-attack. Vi kommer att berätta om problemet och ta upp tidigare attacker samt förslag på åtgärder för att öka säkerheten för både privatpersoner och företag. Vi kommer att utgå från tidigare Case om DDoS och intervjua säkerhetsföretag för att kunna framställa en skyddsstrategi. Därmed hoppas vi att vår uppsats kommer att vara till hjälp för företag som står inför valet att öka säkerheten mot Distributed Denial of Service.</p>

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph.D.)--City University of Hong Kong, 2009. / "Submitted to Department of Manufacturing Engineering and Engineering Management in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 167-187)

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 62 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 46-48).

Thesis (M.S.)--Tennessee Technological University, 2009. / Title from title page screen (viewed on Mar. 3, 2010). Bibliography: leaves 84-89.