A simple and efficient parallel FFT algorithm using the BSP model

We present a new parallel radix-4 FFT algorithm based on the BSP model. Our parallel algorithm uses the group-cyclic distribution family, which makes it simple to understand and easy to implement. We show how to reduce the communication cost of the algorithm by a factor of 3, in the case that the input/output vector is in the cyclic distribution. We also show how to reduce computation time on computers with a cache-based architecture. We present performance results on a Cray T3E with up to 64 processors, obtaining reasonable efficiency levels for local problem sizes as small as 256 and very good efficiency levels for local sizes larger than 2048.     

Ten Ideas for Policymakers to Drive Digital Progress

Innovators continue to find new ways to use information technology (IT) to make our lives better. And looking forward, IT will continue to be a critical component of solutions to many social challenges. But policymakers must create the right environment for technological progress. This article offers ten guiding principals to create technology policy that spurs and sustains digital progress.     

选择低价FPGA开发板付出的高昂代价

在电子产品设计行业，随着FPGA等可编程器件的兴起，一向举止明智的企业开始有点失常。他们竟不对成本与效果、长期影响与工作流程效率进行综合而全面的考虑，仅着眼于短期效益，便对FPGA开发硬件与工具匆匆做出选择。     

Speed Scaling of Tasks with Precedence Constraints

We consider the problem of speed scaling to conserve energy in a multiprocessor setting where there are precedence constraints between tasks, and where the performance measure is the makespan. That is, we consider an energy bounded version of the classic problem Pm | prec | C _max. We extend the standard 3-field notation and denote this problem as Sm | prec, energy | C _max. We show that, without loss of generality, one need only consider constant power schedules. We then show how to reduce this problem to the problem Qm | prec | C _max to obtain a poly-log(m)-approximation algorithm. A preliminary version of this paper appears in Proceedings of the 3rd Workshop on Approximation and Online Algorithms (WAOA 2005). Research of K. Pruhs supported in part by NSF grants CCR-0098752, ANI-0123705, CNS-0325353, CCF-0448196, CCF-0514058, and IIS-0534531. Research of R. van Stee supported by Alexander von Humboldt-Stiftung.     

Non-Discriminatory Automatic Registration of Knock-On Train Delays

Incidents and waiting for train connections are registered by dispatchers as sources of train delays, but route and headway conflicts are not always clearly recognized. Moreover, traffic management and route setting are the primary task of dispatchers and signallers, whilst monitoring and incident registration is not allowed to take up too much of their time. This paper describes a tool that automatically and without discrimination identifies route conflicts and the train numbers involved. It is based on standard train describer and infrastructure messages recorded on the Dutch railway network. The logic of these messages is captured in a coloured Petri net (CPN) model on which a prototype tool for route conflict identification and estimation of knock-on delay has been developed.     

Does regulation stimulate productivity? The effect of air quality policies on the efficiency of US power plants

This research examines the effect of air quality regulations on the productivity of US power plants based on both economic and environmental outputs. Using data envelopment analysis (DEA) to estimate an efficiency measure incorporating both economic and environmental outcomes, we look at changes in efficiency in US power plants over an eleven-year time period (1994–2004) during which several different regulations were implemented for the control of nitrogen oxides (NO_x) and sulfur dioxide (SO₂). The paper then models how estimated efficiency behaves over time as a function of regulatory changes. Findings suggest mixed effects of regulations on power plant efficiency when pollution abatement and electricity generation are both included as outputs.     

ECAD-MCAD协同设计——面向变革的机制

本文介绍了产品设计中电子-机械设计的常规方法,提出了目前ECAD-MCAD协同设计中存在的问题并给出了更加完善的新方案.