城市轨道交通车辆及设备状态监测系统

针对车载设备和部件的实时检测需求,设计了一种由检测终端、车载无线网络、远程服务器组成的车辆及设备状态监测系统,采用无线通信技术和HTTP等网络通信协议,实现对温度、位置等多种传感参数的实时无线远程检测和监测,以及数据存储和智能处理等功能.该系统在城市轨道交通车辆的成功应用表明:有效数据成功传输比例与车辆Wi-Fi网络覆...     

集装箱车辆跟踪和管理

叙述对集装箱车辆跟踪和管理的重要性,介绍实现集装箱车辆跟踪和管理的方法,以及采用3G（GPS、GIS、GSM）高新技术开发而成的集装箱车辆跟踪和管理系统,最后展示应用实例。     

浅谈GPS技术与高等级公路测量

全球定位系统为公路勘测设计工作者提供了一个可靠的提高外业测量精度及进度的工具,随着GPS越来越多地出现在人们的生产、生活中,这一先进的测量手段会被更广泛地应用到公路勘测工作中,从而可提高作业效率,缩短设计周期,推动交通事业的发展和公路的建设.     

字符图像混合二值化方法研究

在模式识别中,二值化效果的好坏直接影响着识别率。针对几种常用的图像二值化自动选取阈值方法,通过计算机仿真试验比较,提出一种全局阈值法和局部阈值法相结合的新的图像混合阈值二值化方法。     

Tracking daily travel; Assessing discrepancies between GPS-derived and self-reported travel patterns

Global Positioning Systems (GPS) technologies have been used in conjunction with traditional one- or two-day travel diaries to audit respondent reporting patterns, but we used GPS-based monitoring to conduct the first assessment to our knowledge of travel reporting patterns using a seven-day travel log instrument, which could reduce response burden and provide multiple-day, policy-relevant information for evaluation studies. We found substantial agreement between participant-reported daily travel patterns and GPS-derived patterns among 116 adult residents of a largely low-income and non-white transportation corridor in urbanized Los Angeles in 2011–2013. For all modes, the average difference between daily GPS- and log-derived trip counts was only about 0.39 trips and the average difference between daily GPS- and log-derived walking duration was about −11.8 min. We found that the probability that a day would be associated with agreement or discrepancies between these measurement tools varied by travel mode and participant socio-demographic characteristics. Future research is needed to investigate the potential and limitations of this and other self-report instruments for a larger sample and a wider range of population groups and travel patterns.     

Technical innovation vs. sustainability – A case study from the Taiwanese automobile industry

The impact of global warming and climate change is the most critical challenge of the 21st century. The greenhouse effect caused by technological development and industrial pollution has accelerated the speed of global warming. To effectively reduce global warming and encourage sustainable enterprise development, a comparative analysis approach is used to examine various domestic automotive products which utilize the up-to-date innovative technology. Their contributions to fuel consumption and emissions of the greenhouse gas, carbon dioxide (CO₂), are then investigated. This study focuses on technical innovation in a conventional engine and output power. The results indicate that innovative engines (such as the Ford turbo petrol/diesel engine, the EcoBoost/TDCi) have improved energy consumption and CO₂ emissions. In addition, an improvement in output power (such as Toyota hybrid vehicles) has also improved energy consumption and CO₂ emissions.     

An empirical assessment of the feasibility of battery electric vehicles for day-to-day driving

Driven by sustainability objectives, Australia like many nations in the developed world, is considering the option of battery electric vehicles (BEVs) as an alternative to conventional internal combustion engine vehicles (ICEVs). In addition to issues of capital and running costs, crucial questions remain over the specifications of such vehicles, particularly the required driving range, recharge time, re-charging infrastructure, performance, and other attributes that will be of importance to consumers. With this in mind, this paper assesses (hypothetically) the extent to which current car travel needs could be met by BEVs for a sample of motorists in Sydney assuming a home-based charging set-up, which is likely to be the primary option for early adopters of the technology. The approach uses five weeks of driving data recorded by GPS technology and builds up home-home tours to assess the distances between (in effect) charging possibilities. An energy consumption model based on characteristics of the vehicle, and the speeds recorded by the GPS is adapted to determine the charge used, while a battery recharge function is used to determine charging times based on the current battery level. Among the most pertinent findings are that over the five weeks, (i) BEVs with a range as low as 60 km and a simple home-charge set-up would be able to accommodate well over 90% of day-to-day driving, (ii) however the incidence of tours requiring out-of-home charging increases markedly for vehicles below 24 kWh (170 km range), (iii) recharge time in itself has little impact on the feasibility of BEVs because vehicles spend the majority of their time parked and (iv) effective range can be dramatically impacted by both how a vehicle is driven and use of electrical auxiliaries, and (v) while unsuitable for long, high-speed journeys without some external re-charging options, BEVs appear particularly suited for the majority of day-to-day city driving in big cities where average journey speeds of 34 km/h are close to optimal in terms of maximising vehicle range. The paper has implications for both policy-makers and auto manufacturers in breaking down some of the (perceived) barriers to greater uptake of BEVs in the future.     

Global convergence of the trial-and-error method for the traffic-restraint congestion-pricing scheme with day-to-day flow dynamics

The traffic-restraint congestion-pricing scheme (TRCPS) aims to maintain traffic flow within a desirable threshold for some target links by levying the appropriate link tolls. In this study, we propose a trial-and-error method using observed link flows to implement the TRCPS with the day-to-day flow dynamics. Without resorting to the origin–destination (O–D) demand functions, link travel time functions and value of time (VOT), the proposed trial-and-error method works as follows: tolls for the traffic-restraint links are first implemented each time (trial) and they are subsequently updated using observed link flows in a disequilibrium state at any arbitrary time interval. The trial-and-error method has the practical significance because it is necessary only to observe traffic flows on those tolled links and it does not require to wait for the network flow pattern achieving the user equilibrium (UE) state. The global convergence of the trial-and-error method is rigorously demonstrated under mild conditions. We theoretically show the viability of the proposed trial-and-error method, and numerical experiments are conducted to evaluate its performance. The result of this study, without doubt, enhances the confidence of practitioners to adopt this method.     

一种新型的船舶航行试验系统

船舶航行实验是船舶完工以后,验收时按规定进行交船试验的重要部分。传统的试验方法是通过GPS定位、人工测量和记录,再进行分析,耗费许多人力、物力。本试验方法是在GPS定位技术、电子海图技术、计算机处理技术基础上设计的新型试验系统。在航行试验时由GPS获取实时的位置信息,将位置信息显示到电子海图上,另外由数据库存储试验数据,试验结束时由计算机自动处理得出试验结果并可打印。使用情况表明该系统可以准确、方便地完成航行试验,试验结束后还可以离线分析,为未来的船舶设计积累相关的资料。     

The Mercator global ocean operational analysis system: Assessment and validation of an 11-year reanalysis

This paper presents Prototype Système 2 Global (PSY2G), the first Mercator global Ocean General Circulation Model (OGCM) to assimilate along-track sea level anomaly (SLA) satellite data. Based on a coarse resolution ocean model, this system was developed mainly for climatic purposes and will provide, for example, initial oceanic states for coupled ocean-atmosphere seasonal predictions. It has been operational since 3 September 2003 and produces an analysis and a two-week forecast for the global ocean every week. The PSY2G system uses an incremental assimilation scheme based on the Cooper and Haines [Cooper, M., Haines, K., 1996. Data assimilation with water property conservation. J. Geophys. Res., 101, 1059-1077.] lifting–lowering of isopycnals. The SLA increment is obtained using an optimal interpolation method then the correction is partitioned into baroclinic and barotropic contributions. The baroclinic ocean state correction consists of temperature, salinity and geostrophic velocity increments and the barotropic correction is a barotropic velocity increment. A reanalysis (1993–2003) was carried out that enabled the PSY2G system to perform its first operational cycle. All available SLA data sets (TOPEX/Poséïdon, ERS2, Geosat-Follow-On, Jason1 and Envisat) were assimilated for the 1993–2003 period. The major objective of this study is to assess the reanalysis from both an assimilation and a thermodynamic point of view in order to evaluate its realism, especially in the tropical band which is a key region for climatic studies. Although the system is also able to deliver forecasts, we have mainly focused on analysis. These results are useful because they give an a priori estimation of the qualities and capabilities of the operational ocean analysis system that has been implemented. In particular, the reanalysis identifies some regional biases in sea level variability such as near the Antarctic Circumpolar Current, in the eastern Equatorial Pacific and in the Norwegian Sea (generally less than 1 cm) with a small seasonal cycle. This is attributed to changes in mean circulation and vertical stratification caused by the assimilation methodology. But the model's low resolution, inaccurate physical parameterisations (especially for ocean–ice interactions) and surface atmospheric forcing also contribute to the occurrence of the SLA biases. A detailed analysis of the thermohaline structure of the ocean reveals that the isopycnal lifting–lowering tends to diffuse vertically the main thermocline. The impact on temperature is that the surface layer (0–200 m) becomes cooler whereas in deeper waters (from 500 to 1500 m), the ocean becomes slightly warmer. This is particularly true in the tropics, between 30°N and 30°S. However it can be demonstrated that the assimilation improves the variability in both surface currents and sub-surface temperature in the Equatorial Pacific Ocean.