Sharif Digital Repository

In this paper, a method for fast processing of data stream tuples in parallel execution of continuous queries over a multiprocessing environment is proposed. A copy of the query plan is assigned to each of processing units in the multiprocessing environment. Dynamic and continuous routing of input data stream tuples among the graph constructed by these copies (called the QueryMega Graph) for each input tuple determines that, after getting processed by each processing unit (e.g., processor), to which next processor it should be forwarded. Selection of the proper next processor is performed such that the destination processor imposes the minimum tuple latency to the corresponding tuple, among... 

The main purpose of this work is to improve the efficiency and performance of a primitive finite volume element method which provides superior capability on a single platform. This method is suitably extended in order to use the advantages of parallel computing on multiprocessors or multicomputers. The method is fully implicit which renders huge sparse linear algebraic kernels. Nevertheless, the attention is focused on solving the sparse system rather than constructing it. The current method is a cell-centered scheme. Since the grid is unstructured, each non-boundary node engages with nodes on three or more surrounding elements around that node. Depending on global node numbering, the... 

The plausibility of embedding cycles of different lengths in the graphs of a network (known as the pancyclicity property) has important applications in interconnection networks, parallel processing systems, and the implementation of a number of either computational or graph problems such as those used for finding storage schemes of logical data structures, layout of circuits in VLSI, etc. In this paper, we present the sufficient condition of the pancyclicity property of OTIS networks. The OTIS network (also referred to as two-level swapped network) is composed of n clones of an n-node original network constituting its clusters. It has received much attention due to its many favorable... 

The plausibility of embedding cycles of different lengths in the graphs of a network (known as the pancyclicity property) has important applications in interconnection networks, parallel processing systems, and the implementation of a number of either computational or graph problems such as those used for finding storage schemes of logical data structures, layout of circuits in VLSI, etc. In this paper, we present the sufficient condition of the pancyclicity property of OTIS networks. The OTIS network (also referred to as two-level swapped network) is composed of n clones of an n-node original network constituting its clusters. It has received much attention due to its many favorable... 

Decision models are essential tools for coastal groundwater management (CGM). A combined simulation-optimization framework is employed to develop these models. One of the main barriers in the widespread application of these models for real-world cases is their large computational burden. Recent advances in efficient computational approaches and robust optimization methods can crack this barrier. This study surveys the scientific basis of CGM to provide an overview on this subject and reviews the-state-of-the-art to clarify recent developments and to outline ideas for improving the computational performance. Key details are presented on the performance and choice of possible robust tools such... 

New methods for the Inverse and forward kinematic analysis of the novel six Degrees of Freedom (6DOF) parallel manipulator which has only two legs are presented. The actuation of the new mechanism is through two base-mounted spherical actuators. In the inverse pose kinematic, active joint variables are directly calculated with no need for the evaluation of passive joint variables. In the forward pose kinematic, closed form solution adopting a new approach is presented. It is shown that the inverse and forward pose kinematic have sixteen and four different solutions, respectively. Moreover, closed form equations for the rate kinematic analysis are proposed. Finally, two different categories... 

In this paper, a parallel algorithm for computing the roots of a given polynomial of degree n on a ring of processors is proposed. The algorithm implements Durand-Kerner's method and consists of two phases: initialisation, and iteration. In the initialisation phase all the necessary preparation steps are realised to start the parallel computation. It includes register initialisation and initial approximation of roots requiring 3n - 2 communications, 2 exponentiation, one multiplications, 6 divisions, and 4n - 3 additions. In the iteration phase, these initial approximated roots are corrected repeatedly and converge to their accurate values. The iteration phase is composed of some iteration... 

By occurring failures in computer networks, routing protocols are triggered to update routing and forwarding tables. Because of invalid tables during update-time, transient loop may occur and packet-drop rate and end-to-end delay increase which means that the quality of service decreases. This paper proposes a parallel architecture for a router to recalculate and update routing table. Simulation results show that with dual-processor architecture, this update time could be up to 40% improved, depending on the network topology and the size of tables. This paper also studies the effect of this speed-up on networks' performability, i.e. the ability to deliver services at predefined level. A... 

Recently, Grid infrastructures have provided wide integrated use of resources. DotGrid intends to introduce required Grid services and toolkits that are implemented as a layer wrapped over the existing operating systems. Our DotGrid has been developed based on Microsoft .NET in Windows and MONO .NET in Linux and UNIX. Using DotGrid APIs, Grid middlewares and applications can be implemented easily. We evaluated our DotGrid capabilities by implementing some applications including a grid-based distributed cryptographic engine and also a typical computational problem. © 2006 IEEE