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Efficient multicore-aware parallelization strategies for iterative stencil computations  [PDF]
Jan Treibig,Gerhard Wellein,Georg Hager
Computer Science , 2010, DOI: 10.1016/j.jocs.2011.01.010
Abstract: Stencil computations consume a major part of runtime in many scientific simulation codes. As prototypes for this class of algorithms we consider the iterative Jacobi and Gauss-Seidel smoothers and aim at highly efficient parallel implementations for cache-based multicore architectures. Temporal cache blocking is a known advanced optimization technique, which can reduce the pressure on the memory bus significantly. We apply and refine this optimization for a recently presented temporal blocking strategy designed to explicitly utilize multicore characteristics. Especially for the case of Gauss-Seidel smoothers we show that simultaneous multi-threading (SMT) can yield substantial performance improvements for our optimized algorithm.
Energy Efficient Military Mobile Base Station Placement  [PDF]
Thabet Mismar,Khaled Elleithy and Saikat Ray,Saikat Ray
International Journal of Wireless & Mobile Networks , 2010,
Abstract: This research deals with an energy efficient network for military mobile base station placement. Theproposed method is based on minimizing the energy loss of military communication networks where thebase station is moving along a preset path and the users are constantly moving in an independent speedand direction. It takes into account the free space loss and the knife edge effect for the energy loss toestablish a path weight for the shortest path model. Then, it evaluates the neighboring points to the basestation for the energy loss of the network in order to find the position at which the minimum energy lossoccurs. The results show a clear energy saving advantage when compared to Lloyd-Max’s method
An iterative merging placement algorithm for the fixed-outline floorplanning  [PDF]
Kun He,Pengli Ji,Chumin Li
Computer Science , 2014,
Abstract: Given a set of rectangular modules with fixed area and variable dimensions, and a fixed rectangular circuit. The placement of Fixed-Outline Floorplanning with Soft Modules (FOFSM) aims to determine the dimensions and position of each module on the circuit. We present a two-stage Iterative Merging Placement (IMP) algorithm for the FOFSM with zero deadspace constraint. The first stage iteratively merges two modules with the least area into a composite module to achieve a final composite module, and builds up a slicing tree in a bottom-up hierarchy. The second stage recursively determines the relative relationship (left-right or top-bottom) of the sibling modules in the slicing tree in a top-down hierarchy, and the dimensions and position of each leaf module are determined automatically. Compared with zero-dead-space (ZDS) algorithm, the only algorithm guarantees a feasible layout under some condition, we prove that the proposed IMP could construct a feasible layout under a more relaxed condition. Besides, IMP is more scalable in handling FOFSM considering the wirelength or without the zero deadspace constraint.
Computationally Efficient Iterative Pose Estimation for Space Robot Based on Vision  [PDF]
Xiang Wu,Ning Wu
Journal of Robotics , 2013, DOI: 10.1155/2013/692838
Abstract: In postestimation problem for space robot, photogrammetry has been used to determine the relative pose between an object and a camera. The calculation of the projection from two-dimensional measured data to three-dimensional models is of utmost importance in this vision-based estimation however, this process is usually time consuming, especially in the outer space environment with limited performance of hardware. This paper proposes a computationally efficient iterative algorithm for pose estimation based on vision technology. In this method, an error function is designed to estimate the object-space collinearity error, and the error is minimized iteratively for rotation matrix based on the absolute orientation information. Experimental result shows that this approach achieves comparable accuracy with the SVD-based methods; however, the computational time has been greatly reduced due to the use of the absolute orientation method. 1. Introduction Vision based methods have been applied to estimate the pose of space robot since 1990s. In these methods, the relative position and orientation between a camera and a robot target are determined with a set of feature points expressed in the three dimensional (3D) object coordinates and their two dimensional (2D) projection in the camera coordinate. The error in position and orientation is usually optimized using the noniterative or iterative algorithms. The noniterative algorithms give an analytical solution for the optimization [1–3], and a typical example of these algorithms includes the method to represent feature points as a linear combination of four virtual control points based on their coordinates [4]. The noniterative methods are generally less time consuming than the iterative methods with acceptable accuracy; however, they are sensitive to observation noise such as image noise, different lighting conditions, and even occlusion by outliers. The iterative approaches, however, achieve better accuracy than the noniterative methods by solving the rotation matrix with a nonlinear least-square method iteratively. A typical iterative method is the Levenberg-Marquardt (L-M) algorithm [5–7], and it has been widely used and accepted as a standard algorithm for least-square problem in photogrammetry. The L-M method is in essentially the combination of the steepest descent method and the Gauss-Newton method in different optimization stages. The steepest descent method is used at the early stage of optimization when the current value of error is still far from the minimum, while the Gauss-Newton method is used at
Performance Advancement of Wireless Sensor Networks using Low Power Techniques and Efficient Placement of Nodes  [PDF]
Fatma Almajadub,Khaled Elleithy
Computer Science , 2014,
Abstract: In this paper, we present optimization techniques for WSNs. Our main goal is to minimize the power consumption and latency. We address the problem of minimizing the energy consumption in WSNs including hardware. ZigBee protocol is used to design nodes on WSN to achieve a very low power consumption rate. Furthermore, we propose to use IRS protocol in WSN within a ZigBee technique to discover information from unaware locations and achieve efficiency of energy and sacrifices latency. Our main idea is to support WSNs with both ZigBee technique and IRS protocol. In addition, we address the problem of efficient node placement for congestion control in WSNs. Thus, we evaluate the performance of specific routing and some algorithms of congestion control when wireless sensor nodes are deployed under different placements of network. To demonstrate the strength of the used algorithms, our simulation in C# proves that ZigBee-IRS- ESRT-Flooding approaches reduce the power consumption from 10% to 19% when compared to existing techniques of low Power and node placement.
Energy Efficient Iterative Waterfilling for the MIMO Broadcasting Channels  [PDF]
Jie Xu,Ling Qiu,Shunqing Zhang
Mathematics , 2012,
Abstract: Optimizing energy efficiency (EE) for the MIMO broadcasting channels (BC) is considered in this paper, where a practical power model is taken into account. Although the EE of the MIMO BC is non-concave, we reformulate it as a quasiconcave function based on the uplink-downlink duality. After that, an energy efficient iterative waterfilling scheme is proposed based on the block-coordinate ascent algorithm to obtain the optimal transmission policy efficiently, and the solution is proved to be convergent. Through simulations, we validate the efficiency of the proposed scheme and discuss the system parameters' effect on the EE.
Multiple Node Placement Strategy for Efficient Routing in Wireless Sensor Networks  [PDF]
Kirankumar Y. Bendigeri, Jayashree D. Mallapur
Wireless Sensor Network (WSN) , 2015, DOI: 10.4236/wsn.2015.78009
Abstract: The advances in recent technology have lead to the development of wireless sensor nodes forming a wireless network, which over the years is used from military application to industry, household, medical etc. The deployment pattern of sensor nodes in Wireless Sensor Network (WSN) is always random for most of the applications. Such technique will lead to ineffective utilization of the network; for example fewer nodes are located at far distance and dense nodes are located at some reason and part of the region may be without the surveillance of any node, where the networks do consume additional energy or even may not transfer the data. The proposed work is intended to develop the optimized network by effective placement of nodes in circular and grid pattern, which we call as uniformity of nodes to be compared with random placement of nodes. Each of the nodes is in optimized positions at uniform distance with neighbors, followed by running a energy efficient routing algorithm that saves an additional energy further to provide connectivity management by connecting all the nodes. Simulation results are compared with the random placement of nodes, the residual energy of a network, lifetime of a network, energy consumption of a network shows a definite improvement for uniform network as that of with the random network.
Efficient Iterative Processing in the SciDB Parallel Array Engine  [PDF]
Emad Soroush,Magdalena Balazinska,Simon Krughoff,Andrew Connolly
Computer Science , 2015,
Abstract: Many scientific data-intensive applications perform iterative computations on array data. There exist multiple engines specialized for array processing. These engines efficiently support various types of operations, but none includes native support for iterative processing. In this paper, we develop a model for iterative array computations and a series of optimizations. We evaluate the benefits of an optimized, native support for iterative array processing on the SciDB engine and real workloads from the astronomy domain.
Methodology for standard cell compliance and detailed placement for triple patterning lithography  [PDF]
Bei Yu,Xiaoqing Xu,Jhih-Rong Gao,David Z. Pan
Computer Science , 2014,
Abstract: As the feature size of semiconductor process further scales to sub-16nm technology node, triple patterning lithography (TPL) has been regarded one of the most promising lithography candidates. M1 and contact layers, which are usually deployed within standard cells, are most critical and complex parts for modern digital designs. Traditional design flow that ignores TPL in early stages may limit the potential to resolve all the TPL conflicts. In this paper, we propose a coherent framework, including standard cell compliance and detailed placement to enable TPL friendly design. Considering TPL constraints during early design stages, such as standard cell compliance, improves the layout decomposability. With the pre-coloring solutions of standard cells, we present a TPL aware detailed placement, where the layout decomposition and placement can be resolved simultaneously. Our experimental results show that, with negligible impact on critical path delay, our framework can resolve the conflicts much more easily, compared with the traditional physical design flow and followed layout decomposition.
A Connectivity-Based Legalization Scheme for Standard Cell Placement  [PDF]
Antonios N. Dadaliaris, Panagiotis Oikonomou, Maria G. Koziri, Evangelia Nerantzaki, Thanasis Loukopoulos, Georgios I. Stamoulis
Circuits and Systems (CS) , 2017, DOI: 10.4236/cs.2017.88013
Abstract: Standard cell placement algorithms have been at the forefront of academic research concerning the physical design stages of VLSI design flows. The penultimate step of a standard cell placement procedure is legalization. In this step the manufacturability of the design is directly settled, and the quality of the solution, in terms of wirelength, congestion, timing and power consumption is indirectly defined. Since the heavy lifting regarding processing is performed by global placers, fast legalization solutions are protruded in state-of-the-art design flows. In this paper we propose and evaluate a legalization scheme that surpasses in execution speed two of the most widely used legalizers, without not only corrupting the quality of the final solution in terms of interconnection wirelength but improving it in the process.
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