高职院校《铁路线路与站场》课程建设思考

根据我国高等职业教育"以能力培养为主导"的教育方针,铁路高职院校开设《铁路线路与站场》课程也应积极做出调整,进行课程的改革建设,使课程更贴近铁路现场实际,更符合工作岗位职业能力的要求。对此,本文阐述了课程建设的几点思考。     

浅谈计算机专业学生企业顶岗实习期间的评价体系建立

本文通过对计算机应用技术专业学生在企业顶岗实习期间进行调查研究,总结出学生在企业顶岗实习中的管理评价体系,用以充分调动学生的积极性和主动性,更好地进行顶岗实习和实现校企合作。     

A saddlepoint approximation to the distribution of the sum of independent non‐identically uniform random variables

Calculating the probability of the corresponding significance point is important for finite sample sizes. However, it is difficult to evaluate this probability when the sample sizes are moderate to large. Under these circumstances, consideration of a more accurate approximation for the distribution function is extremely important. Herein, we performed a saddlepoint approximation in the upper tails for the distribution of the sum of independent non‐identically uniform random variables under finite sample sizes. Saddlepoint approximation results were compared with those for a normal approximation. Additionally, the order of errors of the saddlepoint approximation was derived. © 2014 The Authors. Statistica Neerlandica © 2014 VVS.     

建筑安装岗位能力分析,强化学生职业能力培养

建筑企业需要更多的高素质复合型、技术型人才,以增加企业的在市场中的竞争力。高等职业教育作为高等教育发展中的一个类型,它培养目标符合企业对人才的需求。通过对建筑安装岗位能力分析,强化高职院校在建筑安装专业人才培养过程中的学生职业能力的培养目标。     

Post encroachment time threshold identification for right-turn related crashes at unsignalized intersections on intercity highways under mixed traffic

Abstract

Unsignalized intersections in developing countries experience many serious conflicts between cross-traffic due to indiscipline traffic manoeuvrability. Historically, Post Encroachment Time (PET) has gained attention as a proximal indicator to analyze crossing conflicts. However, identifying an appropriate PET threshold to classify critical conflicts for highly heterogeneous traffic scenario is still an unexplored area. Consequently, this study proposes a novel approach of PET threshold identification with proof of application by collecting data from ten intersections located on four-lane intercity highways in the National Capital Region (NCR), India. Both crossing conflicts and right-turn related crash data (for the left-hand drive) are collected. Their correlations are thoroughly studied for each PET threshold using a quantitative technique considering all and individual vehicle categories. Finally, a qualitative analysis is done by ranking the sites based on cumulative PET and related crashes to verify the proposed quantitative technique. A PET threshold of 1?s is obtained from both the techniques which can be used to identify critical conflicts for unsignalized intersections located on four-lane intercity highways. The proposed methodology will serve as an alternative, faster and effective tool to evaluate the hazardousness of unsignalized intersections located on intercity highways under highly heterogeneous traffic condition.     

Dually sustainable urban mobility option: Shared-taxi operations with electric vehicles

Electric vehicles (EVs) are energy efficient and often presented as a zero-emission transport mode to achieve long-term decarbonization visions in the transport sector. The implementation of a sustainable transportation environment through EV utilization, however, requires the addressing of certain cost and environmental concerns such as limited driving range and battery-charging issues before its full potential can be realized. Nevertheless, a specific type of use of EVs, namely in taxi services, may elicit positive public opinion, as it promises a commitment toward sustainability in urban life. In light of this, this study proposes an integrated approach that combines EV operation with a conceptual design for shared-ride taxi services. As some productivity loss may be naturally expected due to the time spent in charging, it is important to look at whether such performance loss from the passenger and system standpoints can be offset with ingenuity in operational design. In this study, an EV taxi charge-replenishing scheme that can be coupled with a real-time taxi-dispatch algorithm is designed. The proposed EV charging schemes for taxi services are studied via simulations and the effects of the limited driving range and battery-charging details are examined from a system performance viewpoint. The simulation study also reveals illustrative results on the impact of the EV taxi fleet's operation on the charging system. Next, a real-time shared-taxi operation scheme that allows ride sharing with other passengers is proposed to maximize the operational efficiency. The simulation results suggest that the shared-taxi concept can be a viable option to improve on the limitations caused by EV operation. In addition, the importance of projected charging demands and queue delays at different charging locations are also addressed. Some limitations and a future research agenda are also discussed.     

Conditional Persistence of Earnings Components and Accounting Anomalies

We suggest that the failure of investors to distinguish between an earnings component's autocorrelation coefficient (unconditional persistence) and the marginal contribution of that component's persistence to the persistence of earnings (conditional persistence) provides a partial explanation of post‐earnings‐announcement drift, post‐revenue‐announcement drift, and the accrual anomaly. When the conditional persistence of revenue surprises is high (low) relative to its unconditional persistence, both the post‐earnings‐announcement drift and the post‐revenue‐announcement drift are high (low), because investors’ under‐reaction to revenues and earnings is stronger when the persistence of revenue surprises is more strongly associated with the persistence of earnings surprises. Also, the mispricing of accruals decreases substantially when the conditional persistence of accruals is high relative to its unconditional persistence, because investors’ over‐reaction to accruals is mitigated when the persistence of accruals is indeed more strongly associated with the persistence of earnings. Our findings also suggest that financial analysts’ failure to distinguish between unconditional and conditional persistence of revenues and accruals results in more biased revenue and earnings predictions.     

Pareto efficient allocation of an in-motion wireless charging infrastructure for electric vehicles in a multipath network

Electric vehicles (EV) use an eco-friendly technology that limits the greenhouse gas emissions of the transport sector, but the limited battery capacity and the density of the battery are the major barriers to the widespread adoption of EV. To mitigate this, a good method seems to be the innovative wireless charging technology called ‘On-Line EV (OLEV)’, which is a contactless electric power transfer technology. This EV technology has the potential to charge the vehicle’s battery dynamically while the vehicle is in motion. This system helps to reduce not only the size of the battery but also its cost, and it also contributes to extending the driving range before the EV has to stop. The high cost of this technology requires an optimal location of the infrastructure along the route. For this reason, the objective of this paper is to study the problem of the location of the wireless charging infrastructure in a transport network composed of multiple routes between the origin and the destination. To find a strategic solution to this problem, we first and foremost propose a nonlinear integer programming solution to reach a compromise between the cost of the battery, which is related to its capacity, and the cost of installing the power transmitters, while maintaining the quality of the vehicle’s routing. Second, we adapt the multi-objective particle swarm optimization (MPSO) approach to our problem, as the particles were robust in solving nonlinear optimization problems. Since we have a multi-objective problem with two binary variables, we combine the binary and discrete versions of the particle swarm optimization approach with the multi-objective one. The port of Le Havre is presented as a case study to illustrate the proposed methodology. The results are analyzed and discussed in order to point out the efficiency of our resolution method.     

Broadband connected employees and labour productivity: a comparative analysis of 14 European countries based on distributed Microdata access

In this study, the association between information and communication technology (ICT) intensity in firms and labour productivity is explored across 14 European countries for the years 2001–2010. ICT intensity is approximated by the proportion of broadband internet-enabled employees, a novel indicator measuring not only adoption but also diffusion within and among firms. Data have been retrieved by means of the distributed microdata approach (DMD) from registers on business, trade and education as well as from surveys on production, ICT usage and innovation activities in firms held at the national statistical offices. This pioneering approach allows access to otherwise confidential linked firm-level information in dimensions not earlier available. Pooled OLS estimations based on approximately 400,000 observations in harmonised and representative datasets show that in a majority of countries there is a significant and positive relationship between the proportion of broadband internet-enabled employees and labour productivity in firms. However, the strength of the relationship varies across countries and industries. Manufacturing firms receive 50% larger estimates than the services firms, while the latter instead experience the positive association more frequently.     

Urban Geographies of Hesitant Transition: Tracing Socioeconomic Segregation in Post‐Ceauşescu Bucharest

Scholars have raised concerns about the social costs of the transition from state socialism to capitalism in Central and Eastern Europe, and geographers are particularly interested in the spatial expressions and implications of these costs, including apparently increasing residential segregation. Applying a range of segregation measures to 1992 and 2002 census data, this contribution studies socio‐occupational residential segregation in Bucharest. The conclusion is that Bucharest was relatively socio‐spatially mixed at both times; in fact, a modest, yet fully legible, decreasing overall trend is observable. This is at odds with many popular assumptions of the past 20 years.