PENNANT: an unstructured mesh mini‐app for advanced architecture research

This paper describes PENNANT, a mini‐app that operates on general unstructured meshes (meshes with arbitrary polygons), and is designed for advanced architecture research. It contains mesh data structures and physics algorithms adapted from the Los Alamos National Laboratory radiation‐hydrodynamics code FLAG and gives a sample of the typical memory access patterns of FLAG. The basic capabilities and optimization approaches of PENNANT are presented. Results are shown from sample performance experiments run on serial, multicore, and graphics processing unit implementations, giving an indication of how PENNANT can be a useful tool for studies of new architectures and programming models. Copyright © 2014 John Wiley & Sons, Ltd.     

High resolution finite volume computations on unstructured grids using solution dependent weighted least squares gradients

An improved high resolution finite volume method based on linear and quadratic variable reconstructions using solution dependent weighted least squares (SDWLS) gradients has been presented here. An extended stencil consisting of vertex-based neighbours of a cell is used in the higher order reconstructions for inviscid flux computations. A QR algorithm with Householder transformation is used to solve the weighted least squares problem. In case of Navier–Stokes equations, viscous fluxes are discretized in a central differencing manner based on the Coirier’s diamond path. A few inviscid and viscous test cases are solved in order to demonstrate the efficacy of the present method. Progressive improvements in solution accuracy are observed with the increase in the order of variable reconstructions. In most cases, results of quadratic reconstruction show significant improvements over that of linear reconstruction.     

基于蚁群优化算法的虚拟现场可编程门阵列部署策略

针对可重构密码资源池中,如何在最少的现场可编程门阵列（FPGA）上部署虚拟FPGA （vFPGA）的问题,结合FPGA的工作特点和应用场景的需求,在传统蚁群算法的基础上进行了优化,提出了一个基于蚁群优化（ACO）算法的vFPGA部署策略。首先,通过赋予蚂蚁资源状态感知的能力实现各个FPGA之间的负载均衡,同时避免频繁的vFPGA迁移;其次,设计预留空间,有效减少因为租户需求动态变化带来的服务等级协议（SLA）冲突;最后,对CloudSim进行功能扩展,使用合成的工作流进行仿真实验,对该策略性能进行评估。实验结果表明,所提策略可以在保证系统服务质量的前提下,提高FPGA资源利用率,减少FPGA使用量。     

Impact of amplitude weights on power focusing for near‐field‐focused planar arrays

Near‐field‐focused (NFF) arrays have gained great interest owing to its ability to focus the electromagnetic power at a point near to the antenna. The power focusing can basically be reflected by the sidelobe level and the area of the ?3‐dB focal spot at the focal plane. For an ordinary NFF array with the given phase tapering, it would be an effective way to realize the changing of focused power by controlling the feeding‐current amplitude of the array element. In this article, the effects of the amplitude weights of array element rings on the power focusing with reference to an original NFF array are investigated to address this issue. The focus is on the power focusing changing introduced by amplitude weights changing of element rings, in which different cases of amplitude weights changing are considered. The results from amplitude weights changing are compared with that from an original amplitude weights combination, and compared among those from different cases of amplitude weights changing.     

Active‐matrix field‐emission display based on a CNT emitter and a‐Si TFTs

Abstract— An active‐matrix field‐emission display (AMFED), based on carbon‐nanotube (CNT) emitters and amorphous‐silicon thin‐film transistors (a‐Si TFTs), was developed. The AMFED pixels consisted of a high‐voltage a‐Si TFT and mesh‐gated CNT emitters. The AMFED panel demonstrated high performance for a driving voltage less than 15 V. The low‐cost large‐area AMFED approach using a metal‐mesh technology is proposed.     

Active Vibration Control for a Flexible‐Link Manipulator with Input Constraint Based on a Disturbance Observer

This paper mainly focuses on designing an active vibration control for a flexible‐link manipulator in the presence of input constraint and unknown spatially infinite dimensional disturbances. The manipulator we studied can be taken as an Euler–Bernoulli beam, the dynamic model of which has the form of partial differential equations. As the existence of spatially infinite dimensional disturbances on the beam, we first design a disturbance observer to estimate infinite dimensional disturbances. The proposed disturbance observer is guaranteed exponentially stable. Then, taking input saturation into account, a novel disturbance‐observer‐based controller is developed to regulate the joint angular position and rapidly suppress vibrations on the beam, which is the main contribution of this study. The closed‐loop system is validated asymptotically stable by theoretical analysis. The effectiveness of the proposed scheme is demonstrated by numerical simulations.     

一种基于偏微分方程的车辆加速度信号自适应降噪方法

提出一种针对MEMS加速度计信号的基于偏微分方程的自适应降噪方法,该方法不仅能有效克服由于传感器本身原因及车载环境振动噪声带来的影响,获得准确的加速度信号,而且实现容易、实时性好.通过对车辆加速度信号进行建模并叠加真实加速度噪声作为仿真信号,将该方法与选用db6小波基、heursure自适应阈值、4层分解的最佳小波进行降噪性能对比,证明在车辆正常行驶的加速度幅值下,该方法不仅能够取得和小波近似的降噪性能,而且很大程度上减少了运算时间.最后通过对实际车载加速度信号的降噪处理和倾角测量中的应用,再次证明该方法在滤除噪声的同时能够较好体现细节信息,很适合应用在对实时性和准确性要求高的实际工程中.     

Low dimensional disturbance observer‐based control for nonlinear parabolic PDE systems with spatio‐temporal disturbances

In this paper, a design problem of low dimensional disturbance observer‐based control (DOBC) is considered for a class of nonlinear parabolic partial differential equation (PDE) systems with the spatio‐temporal disturbance modeled by an infinite dimensional exosystem of parabolic PDE. Motivated by the fact that the dominant structure of the parabolic PDE is usually characterized by a finite number of degrees of freedom, the modal decomposition method is initially applied to both the PDE system and the PDE exosystem to derive a low dimensional slow system and a low dimensional slow exosystem, which accurately capture the dominant dynamics of the PDE system and the PDE exosystem, respectively. Then, the definition of input‐to‐state stability for the PDE system with the spatio‐temporal disturbance is given to formulate the design objective. Subsequently, based on the derived slow system and slow exosystem, a low dimensional disturbance observer (DO) is constructed to estimate the state of the slow exosystem, and then a low dimensional DOBC is given to compensate the effect of the slow exosystem in order to reject approximately the spatio‐temporal disturbance. Then, a design method of low dimensional DOBC is developed in terms of linear matrix inequality to guarantee that not only the closed‐loop slow system is exponentially stable in the presence of the slow exosystem but also the closed‐loop PDE system is input‐to‐state stable in the presence of the spatio‐temporal disturbance. Finally, simulation results on the control of temperature profile for catalytic rod demonstrate the effectiveness of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.