自相似网络业务流建模方法与比较

随着网络服务的发展．多媒体数据逐渐成为网络业务流的主要内容。基于多媒体数据的网络业务流对服务质量(QoS)提出了更高的要求。通常对服务质量的要求必然转化为对网络资源的需求，然而这个需求的量化必须基于一个能够准确描述网络变化的网络业务流数学模型。同时，网络业务流的不同特征以及研究目的的不同使得自相似网络业务流建模成为一个挑战性的问题。近来，一系列的方法被用于自相似网络业务流建模，本文的作者将这些方法分为两类共四种方法。本文全面分析比较了这些方法，并提出一种分类机制用于根据不同的研究需要确定相应的建模方法。     

基于Linux流控机制的QoS网络

对Linux内核中的流控机制进行剖析，以区分服务(DiffServ)模型为侧重点，根据区分服务模型的体系结构，提出了利用Linux流控机制实现加速转发逐跳行为的应用方案。实验表明，该方案适合于QoS网络的构建。     

交通流视频检测系统的设计与实现

本文描述了交通流视频检测系统的结构、功能和工作原理。根据系统的功能要求，对软件功能模块进行了设计和说明，并着重对车流量统计、车速计算和车类识别的算法进行了描述和实现；文章最后给出了实现结果并讨论了提高检测系统实时性的具体措施。     

"电子警察"管理信息系统初探

“电子警察”技术的发展和系统的扩展，到今天，各城市每天会采集大量的交通违法数据，原有的系统是难以对这些数据进行处理和管理，需要用新的系统来对这些数据进行管理。本文通过对广州市“电子警察”管理信息系统的现状及其存在问题进行了分析和探讨，并对系统体系架构和实现手段进行了研究，以供大家商榷。     

Reprint of “Media reporting of traffic legislation changes in British Columbia (2010)”

IntroductionIn 2010, British Columbia (BC) introduced new traffic laws designed to deter impaired driving, speeding, and distracted driving. These laws generated significant media attention and were associated with reductions in fatal crashes and in ambulance calls and hospital admissions for road trauma.ObjectiveTo understand the extent and type of media coverage of the new traffic laws and to identify how the laws were framed by the media.MethodsWe reviewed a database of injury related news coverage (May 2010–December 2012) and extracted reports that mentioned distracted driving, impaired driving, or speeding. Articles were classified according to: (i) Type, (ii) Issue discussed, (iii) ‘Reference to new laws’, and (iv) ‘Pro/anti traffic law’. Articles mentioning the new laws were reread and common themes in how the laws were framed were identified and discussed.ResultsOver the course of the study, 1848 articles mentioned distraction, impairment, or speeding and 597 reports mentioned the new laws: 65 against, 227 neutral, and 305 supportive. Reports against the new laws framed them as unfair or as causing economic damage to the entertainment industry. Reports in favor of the new laws framed them in terms of preventing impaired driving and related trauma or of bringing justice to drinking drivers. Growing evidence of the effectiveness of the new laws generated media support.ConclusionsBC's new traffic laws generated considerable media attention both pro and con. We believe that this media attention helped inform the public of the new laws and enhanced their deterrent effect.     

DYNAMIC RESOURCE ALLOCATION SCHEME UNDER TRAFFIC CONDITION IN SATELLITE SYSTEMS

As the traffic distribution in China mainland is far from uniform, a new traffic model in China mainland is presented on the basis of per-capita Gross Domestic Product (GDP) and density of population. Based on this characteristic traffic model, a new Traffic Dependent Dynamic Channel Allocation and Reservation (TDDCAR) technique is proposed, the simulation model is built, and the strategies’ performance is evaluated through computer simulation. The simulation results show that, compared to the conventional Fixed Channel Allocation (FCA), TDDCAR estimates the traffic con-ditions in every spot beam and frequently adjusts the traffic according to current traffic conditions. It has achieved a significant improvement in new call blocking probability, handover blocking probability, and fair index, particularly, in heavy traffic conditions. The building of traffic model in China mainland and the analysis of the simulation results has been a key foundation for the study of resource allocation schemes in the future.     

Comprehension and acceptability of on-board traffic information: Beliefs and driving behaviour

Co-Drive on-board traffic information system is a complementary tool providing a dynamic management of transportation infrastructure and traffic as well as the diffusion of accurate real-time information about the road environment and motorists’ driving behaviour. The aim of this study was to examine drivers’ acceptability of Co-Drive by investigating the impact of traffic information provided via on-board display devices on motorists’ beliefs and behaviour.     

Dynamic response of a beam to the train of moving forces driven by an Erlang renewal process

Dynamic response of a beam to a random train of moving forces moving with the same velocity is considered. Unlike a widely used Poisson process model, a more adequate Erlang renewal process is used as a process driving the train of forces. Normal-mode approach is used to convert the problem into that of a renewal driven train of general pulses. Consequently the modal responses are the filtered renewal processes and are expressed as integrals with respect to the response to a single pulse (passage of a force) and to the increments of the counting renewal process. The expressions for the mean values and cross-correlations of modal responses are obtained as single and double integrals, respectively. The results are presented in terms of the renewal density of the underlying Erlang counting process. Mean value and variance of the mid-span deflection of the beam are determined by numerical evaluation of the pertinent integrals. Numerical analysis is carried out for the Erlang processes with integer parameter $k=2$, $k=3$ and 4 and, for comparison, also for a Poisson process. Different traffic conditions such as the velocity and the mean arrival rate of vehicles are taken into account.     

铝合金在自行车上的应用

本文介绍铝合金在交通运输方面尤其在自行车、电动车等方面的应用和发展,并指出自行车这一传统工具在国内某些城市的新用途,成为城市低碳出行的最佳选择之一,间接地为城市交通的发展提供一种节能、环保和惠民的新思路。     

Tail Estimation for Window-Censored Processes

This article develops methods to estimate the tail and full distribution of the lengths of the 0-intervals in a continuous time stationary ergodic stochastic process that takes the values 0 and 1 in alternating intervals. The setting is that each of many such 0–1 processes has been observed during a short time window. Thus, the observed 0-intervals could be noncensored, right-censored, left-censored, or doubly-censored, and the lengths of 0-intervals that are ongoing at the beginning of the observation window have a length-biased distribution. We exhibit parametric conditional maximum likelihood estimators for the full distribution, develop maximum likelihood tail estimation methods based on a semiparametric generalized Pareto model, and propose goodness-of-fit plots. Finite sample properties are studied by simulation, and asymptotic normality is established for the most important case. The methods are applied to estimation of the length of off-road glances in the 100-car study, a big naturalistic driving experiment. Supplementary materials that include MatLab code for the estimation routines and a simulation study are available online.