城市轨道交通直流牵引供电系统接触网残压

对于城市轨道交通来讲,在运行的过程中,直流牵引供电系统是使用最为主要的部件之一。在该系统应用的过程中,接触网残压问题是较为严重的问题,也是当前所出现问题当中比较普遍的一种。对于直流牵引供电系统来讲,当出现接触网残压问题时,可能会对人的生命安全造成严重威胁,同时也会使检修施工和接触网送电保护闭锁等相关工作受到影响,严重拖慢工作进度。因此,论文通过测试、仿真分析和模拟验证等方法,对城市轨道交通直流牵引供电系统接触网残压问题进行了研究与论述。     

Design of limited-stop bus service with capacity constraint and stochastic travel time

This paper develops a mathematical model for the optimal stopping design of limited-stop bus service, which allows each bus vehicle to skip some stops. To better reflect the reality, this paper considers the vehicle capacity and stochastic travel time. Also, vehicles are all allowed to skip stops whereas any stop is not allowed to be skipped by two consecutive vehicles. A hybrid artificial bee colony (ABC) and Monte Carlo method is developed to solve the optimal stopping strategy. Finally, the model and solution method are validated by a numerical example, and a sensitivity analysis is performed on the passenger demand.     

基于模块化多电平的海上风力发电系统的研究

针对海上风力发电远距离传输问题,本文提出了基于模块化多电平的高压直流输电系统(MMC-HVDC)。文章首先介绍了MMC-HVDC的基本工作原理和数学模型,然后提出了一种新型的功率解耦控制算法和电容电压平衡控制策略;利用MATLAB/SIMULINK进行仿真研究,仿真结果表明,MMC-HVDC具有传输功率高,动态响应速度快等优点,是一种具有工程应用价值的高压直流输电拓扑。     

72205综采工作面3300V高压供电技术改造

随着工作面功率的加大,矿井电压过低造成设备启动困难或不启动现象,甚至造成欠电压跳闸,因此1140V电压等级升高到3300V将是煤矿发展的前进方向。     

ROFIBUS现场总线在彩涂板生产线中的研究与实践

现今,我国的彩色涂层钢板的生产已经有了一定的发展,但是其生产水平还是比较低下,不能满足现代社会产业发展理念的需求,不能满足低碳发展、可持续发展的价值理念,PROFIBUS现场总线技术在生产中极大地满足了企业对彩涂板生产的需求。     

Impact of bus rapid transit on housing price and accessibility changes in Sydney: A repeat sales approach

ABSTRACT

New public transport infrastructure is expected to improve accessibility for local residents, and thus contribute to increased land value. The contribution that a bus rapid transit (BRT) system can make to increased land value is less certain than for rail-based systems, with the literature mostly containing bus-based examples from developing countries with extensive BRT networks. This article considers a BRT system named the Liverpool–Parramatta Transitway (LPT) that was implemented in southwestern Sydney in 2003 to improve public transport accessibility in the local area. A repeat sales model is constructed to investigate the impact of the LPT on residential housing prices and accessibility changes using repeat sales data from before and after the opening of the LPT. This identified little price difference between properties close to LPT stations and outside of the area that could be considered as affected by the LPT service coverage. This outcome is at variance with the theoretical underpinning of land value uplift and other empirical evidence relating to the LPT. Hedonic models using the same repeat sales data investigate the study area in more detail, stratifying the sample by housing type and by comparing separate before and after models. These research outcomes identify the extent to which the BRT system has an impact on local housing prices through accessibility improvements to the study area and provide a deeper understanding as to how the quantification of land value uplift from BRT represents one element of the wider economic benefits of a BRT system.     

Do regional house prices converge or diverge in China?

This paper aims to test whether the regional house prices are convergent or divergent in China using a monthly panel data set of China’s 70 large and medium-sized cities from July 2005 to December 2010. This issue is closely related to understanding the efficiency of the country-level housing policies made by China’s central government. The test results suggest that the regional house prices in China are generally divergent, and thereby the country-level policies may be inefficient since they do not explicitly take the strong heterogeneity of China’s regional housing markets into consideration. As a consequence, it may be better for China’s central government to further decentralize and devolve its governance toward the housing market to the local governments.     

Electrification of a city bus network—An optimization model for cost-effective placing of charging infrastructure and battery sizing of fast-charging electric bus systems

The deployment of battery-powered electric bus systems within the public transportation sector plays an important role in increasing energy efficiency and abating emissions. Rising attention is given to bus systems using fast charging technology. This concept requires a comprehensive infrastructure to equip bus routes with charging stations. The combination of charging infrastructure and bus batteries needs a reliable energy supply to maintain a stable bus operation even under demanding conditions. An efficient layout of the charging infrastructure and an appropriate dimensioning of battery capacity are crucial to minimize the total cost of ownership and to enable an energetically feasible bus operation. In this work, the central issue of jointly optimizing the charging infrastructure and battery capacity is described by a capacitated set covering problem. A mixed-integer linear optimization model is developed to determine the minimum number and location of required charging stations for a bus network as well as the adequate battery capacity for each bus line. The bus energy consumption for each route segment is determined based on individual route, bus type, traffic, and other information. Different scenarios are examined in order to assess the influence of charging power, climate, and changing operating conditions. The findings reveal significant differences in terms of required infrastructure. Moreover, the results highlight a trade-off between battery capacity and charging infrastructure under different operational and infrastructure conditions. This paper addresses upcoming challenges for transport authorities during the electrification process of the bus fleets and sharpens the focus on infrastructural issues related to the fast charging concept.     

现金余额型职业养老金计划及其对我国的启示

现金余额型养老金计划是美国职业养老金近年衍生出的创新模式之一,作为混合型计划的一种,其兼具确定给付型和确定缴费型养老金制度的特点。本文运用比较法分析了现金余额型养老金计划的运行机理,进而在分析我国目前职业养老金面,临的困境的基础上,指出现金余额型养老金计划对我国职业养老金建设的借鉴意义,具体包括：DC计划不是职业养老金...     

Multiple Temporalities of Policy Circulation: Gradual,Repetitive and Delayed Processes of BRT Adoption in South African Cities

In 2006, bus rapid transit (BRT) swept across South African cities. Within three years of learning of the Bogotá model of BRT, Johannesburg's Rea Vaya opened, followed shortly by Cape Town's MyCiTi, while several other cities are at various stages of planning and implementation. This article traces the circulation of BRT across the South African urban context to expose the multiple and varied temporalities through which BRT came to appear as the only available solution. These earlier encounters, which include the first published discussion of BRT in South Africa in a 1973 conference report, study visits to Curitiba in the 1990s and a failed attempt to implement a Bogotá‐style BRT system in Cape Town in 2003, were instrumental in creating a fertile ground for later adoption practices. While it may appear as if circulated policies shorten the gestation time from policy introduction to policy adoption, these repeated attempts to implement circulated innovations ensure that the turnover only seems accelerated. This article unravels the story of BRT adoption, departing from the theoretical discussions of the policy circulation process as a rapid phenomenon, instead demonstrating that it is gradual, repetitive and at times delayed.