Real-world gaseous and particle emissions of a Bi-fuel gasoline/CNG Euro 6 passenger car

The objective of the present study is the assessment of the environmental impact of a bivalent (bi-fuel) vehicle, running either on gasoline or compressed natural gas (CNG). To that aim, a Euro 6 passenger car was tested under various real-world driving conditions. In order to cover the full range of conventional powertrains currently in the market, the tests were also repeated on a Euro 6 diesel passenger car. Both cars were driven in two routes, the first complying with the regulation limits and the second going beyond them. Carbon monoxide (CO), nitrogen oxides (NO_x) and particle number (PN) emissions were recorded using a Portable Emissions Measurement System (PEMS). Apart from the aggregated emission levels, in g/km, the exact emission location along the route was also assessed. Natural gas proved beneficial for CO and PN emissions, the level of which always remained below the respective legislation limits. On the other hand, under the dynamic driving conditions with gasoline, the relevant limits were exceeded. Cold start, occurring at the beginning of the urban part, and motorway driving were identified as major contributors to total emissions, especially in gasoline mode. However, the application of natural gas was associated with a penalty in NO_x emissions, which were significantly increased as compared to gasoline. Local peaks within the urban part were identified in CNG mode. In any case, the diesel vehicle was by far the highest NO_x emitter.     

海洋核动力平台自然冷却供冷系统节能性分析

针对海洋核动力平台示范工程运行厂址及其堆舱区供冷需求特点,为提高运行经济性,设计了利用自然冷源——海水的供冷系统,通过建立系统能耗模型,分析了不同海水温度下系统运行工况及相应的能耗和能效比。根据运行厂址实测海水温度,计算了系统优化前后全年运行能耗,并分析了节能效果,系统优化后节能15.7%。     

Characterizing the fragmentation level of Italian’s National Parks due to transportation infrastructures

In the last decades, due to the population increase and the relative need of new land to cultivate, expand urban centers and develop transportation networks, most of the Italian natural protected areas are subject to different typologies of human pressures that generally cause habitat fragmentation. This process represents a major concern for biodiversity conservation and a key driver of species loss.The main purpose of this paper was to investigate levels of natural habitat fragmentation due to roads and railways networks in the Italian National Parks (INP_S) through the use of an Infrastructural Fragmentation Index (IFI).All the operations (geospatial analysis, image classification, and fragmentation analysis) were performed using a Geographic Information System (GIS) software for elaborating a national database. The obtained results include an IFI value for each natural territorial unit inside any INP. Moreover, in order to highlight which are the INP_S characterized by higher infrastructural fragmentations, an IFI weighted mean was calculated for each INP. These results represent important indicators for the prioritization of biodiversity conservation interventions and the planning of a INP_S sustainable management.     

System dynamics of urban traffic based on its parking-related-states

The urban parking and the urban traffic systems are essential components of the overall urban transportation structure. The short-term interactions between these two systems can be highly significant and influential to their individual performance. The urban parking system, for example, can affect the searching-for-parking traffic, influencing not only overall travel speeds in the network (traffic performance), but also total driven distance (environmental conditions). In turn, the traffic performance can also affect the time drivers spend searching for parking, and ultimately, parking usage. In this study, we propose a methodology to model macroscopically such interactions and evaluate their effects on urban congestion.The model is built on a matrix describing how, over time, vehicles in an urban area transition from one parking-related state to another. With this model it is possible to estimate, based on the traffic and parking demand as well as the parking supply, the amount of vehicles searching for parking, the amount of vehicles driving on the network but not searching for parking, and the amount of vehicles parked at any given time. More importantly, it is also possible to estimate the total (or average) time spent and distance driven within each of these states. Based on that, the model can be used to design and evaluate different parking policies, to improve (or optimize) the performance of both systems.A simple numerical example is provided to show possible applications of this type. Parking policies such as increasing parking supply or shortening the maximum parking duration allowed (i.e., time controls) are tested, and their effects on traffic are estimated. The preliminary results show that time control policies can alleviate the parking-caused traffic issues without the need for providing additional parking facilities. Results also show that parking policies that intend to reduce traffic delay may, at the same time, increase the driven distance and cause negative externalities. Hence, caution must be exercised and multiple traffic metrics should be evaluated before selecting these policies.Overall, this paper shows how the system dynamics of urban traffic, based on its parking-related-states, can be used to efficiently evaluate the urban traffic and parking systems macroscopically. The proposed model can be used to estimate both, how parking availability can affect traffic performance (e.g., average time searching for parking, number of cars searching for parking); and how different traffic conditions (e.g., travel speed, density in the system) can affect drivers ability to find parking. Moreover, the proposed model can be used to study multiple strategies or scenarios for traffic operations and control, transportation planning, land use planning, or parking management and operations.     

加强铁路法制建设促进铁路跨越式发展

加强铁路法制建设,是铁路跨越式发展战略的重要组成部分。近年来,铁道部围绕铁路跨越式发展对法制保障的需要,加大了法制建设力度,取得了一系列成果,立法取得重大突破,依法行政得到有序推进,企业的法治化管理得到加强。但也存在一些问题,铁路法规体系还不完整,依法行政理念还不深入,企业法律风险意识还不强。需要重点抓好:健全铁路法规体系、全面推进依法行政、依法推进铁路改革、依法规范铁路运输经营管理、依法保障大规模铁路建设的实施、加大法制宣传教育力度、加强法律队伍建设等工作,确保铁路跨越式发展战略的顺利实施。     

既有数字调度系统升级为FAS系统

通过工程实践,详细介绍了将既有线的数字调度设备经过添加少量设备和元件升级为固定接入交换系统(FAS)的方法,以实现调度系统数字调度和移动调度一体化。     

城市一卡通IC卡在线加值之解决方案

论文首先对城市一卡通IC卡在线加值解决方案的国内外发展背景进行了分析论述,提出IC卡在线加值要以住建部密钥系统为安全基础保证,并分析了IC卡在线加值安全保证的住建部密钥系统的的重要性,并对住建部密钥的结构进行分解分析；提出了IC卡在线加值系统的系统层次,安全容错方法,并归纳了在线充值的数据处理流程.     

Price of anarchy for non-atomic congestion games with stochastic demands

We generalize the notions of user equilibrium, system optimum and price of anarchy to non-atomic congestion games with stochastic demands. In this generalized model, we extend the two bounding methods from Roughgarden and Tardos (2004) and Correa et al. (2008) to bound the price of anarchy, and compare the upper bounds we have obtained. Our results show that the price of anarchy depends not only on the class of cost functions but also demand distributions and, to some extent, the network topology. The upper bounds are tight in some special cases, including the case of deterministic demands.     

船用交流电机基于DSP的软启动控制系统研究

交流电机在船舶上的应用非常广泛,但其启动冲击电流比较大,对电网和电机的冲击比较大,因此对电机启动控制的研究非常重要。本文分析介绍了软启动器的特点、用途和其在船舶上的应用,并根据软启动器的原理,利用DSP和晶闸管,设计了一个基于DSP控制的调速系统。通过控制晶闸管的导通角度和导通时间,来实现电机的平滑启动,以降低启动对电网和电机的冲击。最后对电机的软启动控制系统进行了分析。     

智能交通在城市交通中的应用探讨

智能交通的研究课题是如何把现代的高科技与交通联系起来.结合实际阐述了智能交通系统在城市交通管理中的作用和重要性,针对我国交通现状提出了一些建议,并对智能交通未来的发展进行了探讨.