基于CPCIE的高速数据交换中心的设计

针对高速图像处理的需求,本文设计实现了一种混合结构的CPCIE交换板.根据高速串行通信的电气特性及CPCIE系统规范要求,将PCIE链路信号和高速串行图像信号合成一组,按照CPCIE交换板信号的拓扑关系,传到各个下游槽位.在标准的CPCIE机箱中,本系统单板实现了PCI Express系统扩展功能和高速光纤图像的动态交...     

公交车调度优化模型

本文主要研究了一条公交线路在其每时段内各个车站点的客流统计数据为已知情况下的车辆运行计划时刻表的制定问题.一般情况下,公交公司在调查研究取得一定数据的基础上都是按"接连开出"的方法安排工作日的车辆行车调度表,使得在运行期内,一组车辆"鱼贯而出,再鱼贯而入",而我们主要研究了随着时间和空间上客流不均衡性的变化,车辆应如何调度的规律,建立了目标规划模型.实现了"有早出,有晚出",车辆有多有少的调度计划.在保证一定效益和顾客满意的情况下,使在岗车辆的总运行时间最短.所有的计算都在计算机上实现,得出了调度时刻表,且最少的车辆数为42,顾客与公交公司的满意程度比为:0.68:0.46.     

A bi-objective optimization approach for exclusive bus lane selection and scheduling design

This study proposes a methodology to solve the integrated problems of selection and scheduling of the exclusive bus lane. The selection problem intends to determine which roads (links) should have a lane reserved for buses while the scheduling problem intends to find the time period of the application. It is formulated as a bi-objective optimization model that aims to minimize the total travel time of non-bus traffic and buses simultaneously. The proposed model formulation is solved by the hybrid non-dominated sorting genetic algorithm with Paramics. The results show that the proposed methodology is workable. Sets of Pareto solutions are obtained indicating that a trade-off between buses and non-bus traffic for the improvement of the bus transit system is necessary when the exclusive bus lane is applied. This allows the engineer to choose the best solutions that could balance the performance of both modes in a multimode transport system environment to achieve a sustainable transport system.     

用PCI9052实现的高性能CCD图像采集设备

在介绍PCI9052主要功能的基础上，以具体PCI图像采集卡设计为例给出了技术上的实现办法。采用旁路计算机系统内存，打破了记录系统的数据传输仅为为二分之一PCI总线带宽的速度限制，有效地提高了PCI总线上设备之间的传输率。     

公交车调度

本文利用多目标优化方法建立了公交车调度的数学模型.首先通过数据分析,并考虑到方案的可操作性,将一天划分为早高峰前,早高峰,早高峰和晚高峰之间,晚高峰及晚高峰后5个时段;引入车辆的平均满载率,乘客的等待抱怨程度及拥挤抱怨程度作为三个目标函数,建立了三目标优化模型;通过加权,将三个目标函数合并为一个目标函数.运用MATLAB数学软件计算出了上行、下行各个时段发车的时间间隔:上行各时段时间间隔分别为5、2、4、3、15,下行各时段时间间隔分别为10、2、5、3、8(单位:分钟);所需总车辆数为52辆,共发车534次,公交公司的平均满载率为82.094%,抱怨顾客的百分比为0.91%.通过模型检验得出所求模型较为稳定.最后,通过对原始数据的分析和处理,得出在进入和离开乘客高峰时期,局部缩短采集数据时间间隔是改善调度方案的有效方法.     

Another Look at the Process Capability Index

Process capability indices (PCIs) have been widely used in manufacturing industries. In this paper, we take a very specific view that a proper value of the process capacity index (PCI) represents the true yield of the process. Following this logic, a universal PCI, C_y, is proposed and derived. The superiority of the new PCI is presented in theory and demonstrated through examples. Copyright © 2005 John Wiley & Sons, Ltd.     

Yield‐Based Capability Index for Evaluating the Performance of Multivariate Manufacturing Process

Process capability indices (PCIs) have been widely used in the manufacturing industry providing numerical measures on process precision, accuracy and performance. Capability indices measures for processes with a single characteristic have been investigated extensively. However, an industrial product may have more than one quality characteristic. In order to establish performance measures for evaluating the capability of a multivariate manufacturing process, multivariate PCIs should be introduced. In this paper, we analyze the relationship between PCI and process yield. The PCI EC_pk is proposed based on the idea of six sigma strategy, and there is a one‐to‐one relationship between EC_pk index and process yield. Following the same, idea we propose a PCI MEC_pk to measure processes with multiple characteristics. MEC_pk index can evaluate the overall process yield of both one‐sided and two‐sided processes. We also analyze the effect of covariance matrix on overall process yield and suggest a solution for improving overall process yield. Copyright © 2013 John Wiley & Sons, Ltd.     

The evidence of systematic noise in non-patent references: A study of New Zealand companies’ patents

Since the pioneering studies of Carpenter & Narin (1983), and Narin & Noma (1985), non-patent references (NPRs) in patent documents have been widely used as an indicator of science-technology links. Meyer (2000) reviewed previous work in the patent citation literature and found that citation links between patents and papers are, if not explicitly, at least implicitly viewed as an indication of the contribution of science to technology. Using a sample of 850 patents of New Zealand companies granted by the USPTO between 1976 and 2004, we find evidence of systematic noise in NPR data. We suggest that future research should pay close attention to heterogeneity among countries, and that one should demonstrate more caution in applying and interpreting results based on the NPR methodology.     

基于外围部件互连总线接口电路的实现及应用

设计一种基于PCI（Peripheral Componet Interconnect)总线的接口电路，对PCI接口的方式进行分析比较，研究PCI配置寄存器的配置方式，给出一个应用实例。利用专用PCI芯片可以很好地完成PCI接口，并可在本地端提供方便的应用接口。供用户完成自己的特定功能。该PCI接口电路是切实可行的，具有高效，低成本等优点，可以很方便地移植到用户系统中。     

龙芯2号原型系统北桥的设计与实现

针对龙芯2号原型系统中主要I/O数据通路上数据流的特点,设计并实现了一款适用于龙芯2号原型系统的北桥。在此北桥的设计中提出并实现了一种用于外部设备互连(PCI)主桥(PCI host bridge,PHB)的数据传输优化方法,这种方法通过自适应的写合并、PCI写数据及时收集重打包和采用固定开销的分阶段PCI读数据预取策略,提高了PCI主桥中数据传输的效率。实验结果表明,所设计的北桥可以充分的利用PCI总线带宽,并且在处理PCI总线上的直接内存访问(DMA)读数据流和处理器更新显卡显存的PCI写数据流时相对同类系统而言具有明显的性能优势。     

Factors influencing students' usage of school bus seat belts: an empirical analysis of the Alabama pilot project

The Alabama State Department of Education and the Governor's Study Group on School Bus Seat Belts authorized and funded a research project to investigate the effects of lap-shoulder seat belts on Alabama school buses. This article performs an empirical analysis to address an important component of the study – factors that impact students’ decisions about wearing seat belts or not on school buses. Discrete choice modeling framework is applied to quantify relative influences of various factors. To obtain the disaggregate level information on individual student's characteristics and trip properties, a new data collection protocol is developed. Eleven variables are investigated and eight of them are found to have significant impacts. They are age, gender, the home county of a student, a student's trip length, time of day, presence and active involvement of bus aide, and two levels of bus driver involvement. The resulting model fits the data well and reveals several trends that have been overlooked or underestimated in the literature. The model can also be used to predict the change of seat belt usage rate caused by the change of impact factors. This is helpful in identifying the most cost-effective ways to improve compliance rate, which is critical to bring the added safety benefit of seat belts into effect. This article is the first to quantify relative impacts of a range of variables using rigorous statistical modeling techniques. This study will contribute to the literature and provide valuable insights to the practice of school transportation management.     

TCP with header checksum option for wireless links: An analytical approach towards performance evaluation

TCP performs poorly in wireless mobile networks due to large bit error rates. Basically, the TCP sender responds to these losses as if they were due to congestion in the network, and reduces the congestion window unnecessarily. In earlier work, it has been shown that adding a TCP header checksum is very useful in differentiating between congestion loss and corruption loss. With the modified TCP, receivers can explicitly indicate corruption of received packets by generating “Explicit Loss Notifications (ELNs).” This paper focuses on an analytical study of this modified TCP protocol. We derive an expression for the probability of a receiver generating successful ELN, assuming a generic link layer protocol for data transfer over wireless links. Next, we develop an analytical approach for TCP throughput evaluation under the modified scheme. We compare the throughput results obtained by analysis and simulation, and find very close agreement between the two sets. We also compare the performance of the modified scheme with the standard NewReno TCP, and find considerable improvement in data throughput over wireless links.     

A computerized approach to the New York Cityschool bus routing problem

Transportation is an area where operations research has had a great impact on systems by improving service quality and reducing operating costs. In particular, one of the most visible applications is in routing and scheduling school buses. In this paper we investigate various issues related to the development of a computerized system to help route and schedule school buses throughout the five boroughs of New York City. The routing problem presents many challenges because of its magnitude, the vast resources involved and the intricacies one encounters when routing in a completely urban environment. We analyze various aspects of the problem including the generation of routes in the Borough of Manhattan and provide a solution requiring far fewer buses than are currently in use. The computerized system, called CATS, incorporating many of the results obtained in this research, is currently being used to route Special Education students.     

Assessing factors causing severe injuries in crashes of high-deck buses in long-distance driving on freeways

High-deck buses that have a higher center of gravity traveling at an excessive speed have a higher likelihood of causing serious and fatal accidents when drivers lose control of the vehicle. In addition, drivers who suffer from fatigue in long-distance driving increase the likelihood of serious accident. This paper examines the effects of risk factors contributing to severe crashes associated with high-deck buses used for long-distance driving on freeways. An ordered logit and latent class models are used to examine significant factors on the severity of injuries in crashes related to high-deck buses. Driver fatigue, drivers or passengers not wearing a seat belt, reckless driving, drunk driving, crashes occurred between midnight and dawn, and crashes occurred at interchange ramps were found to significantly affect the severity of injuries in crashes involving high-deck buses. Safety policies to prevent severe injuries in crashes involving high deck buses used for long-distance runs on freeways include: (1) restricting drivers from exceeding the limit of daily driving hours and mandating sufficient rest breaks; (2) installing an automatic sleep-warning device in the vehicle; (3) drivers with obstructive sleep apnea syndrome or sleep disorders should be tested and treated before they are allowed to perform long hours of driving tasks; (4) educating the public or even amending the seatbelt legislation to require all passengers to wear a seat belt and thus reduce the chance of ejection from a high-deck bus and prevent serious injuries in a crash while traveling at a higher speed on freeways.     

Cost savings from a sustained compulsory breath testing and media campaign in New Zealand

This paper evaluates three approaches to compulsory breath testing (CBT) where all drivers stopped are tested: (1) intensive, moderate-profile CBT (plus zero alcohol tolerance for drivers under age 20, which was implemented simultaneously, remains in effect, and unavoidably is commingled with CBT in the effectiveness estimates); (2) CBT plus an enhanced media campaign; and (3) shifting to aggressively visible booze buses, which also streamlined drunk-driver processing, plus enhanced community campaigns against drunk-driving. Approaches 1 and 2 were implemented throughout New Zealand (NZ) in 1993 and 1995. Booze buses and community programs were added for about one-third of the country in late 1996. ARIMA time series models estimated the impact on serious and fatal injury crashes between 10 p.m. and 3 a.m., a proxy for alcohol-related crashes. A benefit-cost analysis assessed return on investment. Cost savings were analyzed from four perspectives: societal, governmental, drunk-drivers', and people other than drunk-drivers (external cost). CBT plus zero tolerance reduced expected night-time crashes by 22.1% and enhanced media by 13.9%. Booze buses yielded a further 27.4% reduction where implemented. The program and associated crash reduction persisted until at least 2001 (the most recent data available). Estimated societal benefit-cost ratios were 14 for CBT, 19 for CBT plus enhanced media, and 26 for the comprehensive package. Government saved more than it spent on the program, especially with booze buses. Aggressive CBT plus zero alcohol tolerance for youth, media blitzes, and booze buses proved dramatically effective. Together, these four interventions halved late night serious and fatal injury crashes. Sustained effort seems to be critical. Better outcomes may be achieved with staged, increasingly visible and inescapable checkpoints than with an "ideal" initial program. It appears CBT is best implemented in conjunction with broader community-centered efforts to reduce drunk-driving.     

Factors affecting the probability of bus drivers being at-fault in bus-involved accidents

Previous research has provided little insight into factors that influence the probability of bus drivers being at-fault in bus-involved accidents. In this study, an analysis was conducted on accident data compiled by a bus company that include an assessment on whether the bus driver was deemed by the company to hold primary responsibility for accident occurrence. Using a mixed logit modelling approach, roadway/environmental, vehicle and driver related variables that were identified to be influential were road type, speed limit, traffic/lighting conditions, bus priority, bus age/length and driver's age/gender/experience/historic at-fault accident record. Results were indicative of possible confined road-space issues that bus drivers face along routes with roadside traffic friction and point to the provision of exclusive right of way for buses as a possible way to address this. Results also suggest benefits in assigning routes comprising mainly divided roads as well as newer and shorter buses to less experienced drivers.     

Parallel algorithms and architectures based on pipelined optical buses

Optical signals have some unique properties, such as unidirectional propagation and precisely predictable path delays in waveguides, which are not shared with their electronic counterparts. By taking advantage of these unique properties, we can use optical interconnections to achieve speed improvements in single-instruction stream, multiple-data streams (SIMD) computations. We first show how optical buses can be utilized advantageously in SIMD architectures to obtain fast solutions to several computational problems, including integer addition, counting and logical XOR, sorting, and fast Fourier transforms. We then present a new implementation of the optical buses to meet the unique requirements in highperformance optical-electronic computing systems. Such an implementation allows the transmission of messages at speeds ideal for optics and, in the meantime, the processing of data at speeds ideal for electronics, dealing successfully with the speed limitation by electronics in optical-electronic computers. The primary effects of this bimodal optical bus are twofold: reduction of fiber lengths and reduction of system latency. Reduced latency is a unique advantage to an optical bimodal bus. Together, these observations make optical-bus-based architectures appear to be a promising approach to SIMD processing.     

用于计算机总线并行互连的高速光互连链路

设计和实现了基于计算机ＰＣＩ总线的高速光互连链路。链路的网络接口卡具有３２位并行输入／输出接口,中间采用时分复用同步传输技术,在一根光纤中实现了ＰＣＩ总线数据的虚拟并行传输。链路的最高数据传输速率为１２５０Ｍｂｉｔ／ｓ,使用多模光纤时最大传输距离为６４０ｍ,在１０米传输距离时,通信延迟低于２００ｎｓ。     

A Method of Estimating the Process Capability Index from the First Four Moments of Non‐normal Data

A method is presented to estimate the process capability index (PCI) for a set of non‐normal data from its first four moments. It is assumed that these four moments, i.e. mean, standard deviation, skewness, and kurtosis, are suitable to approximately characterize the data distribution properties. The probability density function of non‐normal data is expressed in Chebyshev–Hermite polynomials up to tenth order from the first four moments. An effective range, defined as the value for which a pre‐determined percentage of data falls within the range, is solved numerically from the derived cumulative distribution function. The PCI with a specified limit is hence obtained from the effective range. Compared with some other existing methods, the present method gives a more accurate PCI estimation and shows less sensitivity to sample size. A simple algebraic equation for the effective range, derived from the least‐square fitting to the numerically solved results, is also proposed for PCI estimation. Copyright © 2004 John Wiley & Sons, Ltd.