铁路出发旅客衔接方式选择的复合异质性模型

鉴于多属性决策中存在的属性偏好和处理两类异质性现象,以铁路出发旅客衔接方式选择问题为对象,对两类异质性的效用表达进行了讨论,构建了能同时描述旅客属性偏好和处理异质性的复合异质性(Hybrid)非集计模型.采用成都东客站SP调查数据进行模型标定,结果表明,Hybrid模型的拟合度优于单一异质性模型.旅客属性处理规则自述结果与Hybrid模型分类结果的对比分析表明,模型对旅客属性处理特征的表达准确.进一步对不同类型旅客属性标定结果的分析显示,Hybrid模型可实现对衔接方式选择行为的精细化描述.     

基于异构模型的铁路出发旅客衔接时间价值

旅客时间价值是开展区域综合交通一体化研究的重要参数.本文针对现有文献中铁路旅客衔接时间价值研究较少、异构模型计算结果的比较不够充分等问题,以成都铁路东客站出发旅客衔接方式选择SP数据为依托,建立了MNL、ML、LCL、Hybrid等异构模型,对异构模型所得旅客个体和样本总体的等候时间价值、车内时间价值进行了比较.结果表明：模型结构对时间价值求解有较大影响,ML中单侧三角分布模型求解结果较为合理;Hybrid模型在拟合效果上表现优良,但在个体等候时间价值求解结果中呈现出较为明显的偏态性,给总体统计描述带来一定的困难.由于目前尚无关于时间价值的明确比选方法,应用中可考虑取异构模型计算结果的均值.     

A railway capacity determination model and rail access charging methodologies

This article discusses approaches to the determination of railway capacity and the significance of the following factors on capacity: mix of trains, length and weight of trains, direction of train travel, acceleration and deceleration, stopping protocols of trains, location and length of crossing loops, location of signals, length of sections, dwell times and sectional running times. A more accurate method to calculate railway capacity is developed using previously unaddressed aspects for capacity determination. Capacity and pricing are two key issues for organizations involved with open track access regimes. A train access charging methodology is therefore developed and incorporated into a railway capacity determination model.     

Design and evaluation of a grade-separated intersection: a case study of the proposed Belgrade ‘Hipodrom’

This paper presents the evaluation results of three traffic solutions for the complex grade-separated intersection located in the old part of Belgrade at the junction with the new bridge over the Sava River. The corridor to which the intersection belongs together with the new river bridge are parts of a great urban artery called the Inner Half Semi-Ring Road (IHSRR). The traffic solutions that are evaluated are defined in the preliminary design phase, based on two opposed concepts: a complete grade separation of all intersection legs (the CPV alternative – ‘grade-separated’) and a grade separation designed to minimise construction costs (DMC 1 and 2 alternatives – ‘minimise cost’). The evaluation procedure is conducted in three steps: first, the score based on expert assessment of the functionality of the design solutions is determined; second, the alternatives are ranked according to the value of a set of state indicators obtained by micro-simulation using PTV–VISSIM 4.10; and third, the final score is obtained by multi-criteria evaluation using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The results of the first evaluation step show a small advantage for DMC 2, a sub-alternative of the DMC 1 alternative. The results of the micro-simulation give advantage to the DMC 1 alternative. The multi-criteria evaluation provides a better ‘goodness factor’ for the CPV alternative against the DMC 1 alternative. At the same time, the least construction cost favours alternative DMC 1.     

大开口型散货船运木功能设计要点分析

针对37 000 DWT大开口散货/运木船,比较大开口型散货船与普通散货船特点,分析大开口型散货船运木功能的实现方面需要注意的绑扎系统的布置与强度、安全通道的布置与操作空间、甲板面布置与舾装件的保护等的设计要点,给出设计方案和建议。     

基于GPS、GPRS的货箱跟踪终端的设计和实现

为确保货箱在航海中的安全,研制了一种基于GPRS、GPS的货箱跟踪终端.该系统以ARM7TDMI-S LPC 2292为核心处理器,利用GPRS作为数据通信载体,同时终端提供继电器接口和密码键盘,可以实现对货柜的安全控制.介绍系统的硬件原理,并介绍具体的软硬件设计.     

北江白石窑水利枢纽下游引航道通航水力学试验研究

通过对原有白石窑水利枢纽船闸进行改扩建来提高航运能力,将原来的一线船闸改建,同时在改建船闸左岸增设二线船闸。根据白石窑水利枢纽通航建筑物的整体定床模型试验成果,研究该工程改扩建后的通航条件。针对由于枢纽下游主河槽与船闸轴线交角较大以及枢纽下游主河槽河床高出下引航道口门区较多而引起的船闸下游口门区及连接段的斜流、乱流等不利通航水流条件,提出了合理有效的整改措施。该试验成果可供以后类似工程参考和借鉴。     

多媒体教室网络接入设计与实现

伴随着教育信息化的发展,网络已经成为多媒体教学必不可少的教学手段.因此,对未接入网络的教学区教学设备进行网络布线、管理及升级显得非常必要.本文阐述了学院教学楼多媒体教室网络接入的设计思想和实施方案,对项目实施中的难点和关键点进行了深入分析和研究实现,为云空间的教学手段提供了优质的保障.     

A simulation study of service differentiation for the bandwidth request scheme in fixed IEEE 802.16 network

Various flexible mechanisms related to quality of service (QoS) provisioning have been specified for uplink traffic at the medium access control (MAC) layer in the IEEE 802.16 standards. Among the mechanisms, contention based bandwidth request scheme can be used to indicate bandwidth demands to the base station for the non-real-time polling and best-effort services. These two services are used for most applications with unknown traffic characteristics. Due to the diverse QoS requirements of those applications, service differentiation (SD) is anticipated over the contention based bandwidth request scheme. In this paper we investigate the SD with the bandwidth request scheme by means of assigning different channel access parameters and bandwidth allocation priorities at different packets arrival probability. The effectiveness of the differentiation schemes is evaluated by simulations. It is observed that the initial backoff window can be efficient in SD, and if combined with the bandwidth allocation priority, the SD performances will be better. Foundation item: the National Basic Research Program (973) of China (No. 2005C13321804)