Modeling Crash Risk at Rail-Highway Grade Crossings by Track Class

The Federal Railroad Administration (FRA)’s Web Based Accident Prediction System (WBAPS) is used by federal, state and local agencies to get a preliminary idea on safety at a rail-highway grade crossing. It is an interactive and user-friendly tool used to make funding decisions. WBAPS is almost three decades old and involves a three-step approach making it difficult to interpret the contribution of the variables included in the model. It also does not directly account for regional/local developments and technological advancements pertaining to signals and signs implemented at rail-highway grade crossings. Further, characteristics of a rail-highway grade crossing vary by track class which is not explicitly considered by WBAPS. This research, therefore, examines and develops a method and models to estimate crashes at rail-highway grade crossings by track class using regional/local level data. The method and models developed for each track class as well as considering all track classes together are based on data for the state of North Carolina. Linear, as well as count models based on Poisson and Negative Binomial (NB) distributions, was tested for applicability. Negative binomial models were found to be the best fit for the data used in this research. Models for each track class have better goodness of fit statistics compared to the model considering data for all track classes together. This is primarily because traffic, design, and operational characteristics at rail-highway grade crossings are different for each track class. The findings from statistical models in this research are supported by model validation.

The CA model for traffic-flow at the grade roundabout crossing

The cellular automaton model is suggested to describe the traffic-flow at the grade roundabout crossing. After the simulation with computer, the fundamental properties of this model have been revealed. Analysing this kind of road structure, this paper transforms the grade roundabout crossing with inner-roundabout-lane and outer-roundabout-lane into a configuration with many bottlenecks. Because of the self-organization, the traffic flow remains unblocked under a certain vehicle density. Some results of the simulation are close to the actual design parameter.

Key factors contributing to crash severity at highway-rail grade crossings

The purpose of this paper is to develop and com- pare the preferred multinomial logit （MNL） and ordered logit （ORL） model in identifying factors that are important in making an injury severity difference and exploring the impact of such explanatory variables on three different severity levels of vehicle-related crashes at highway-rail grade crossings （HRGCs） in the United States. Vehicle-rail crash data on USDOT highway-rail crossing inventory and public crossing sites from 2005 to 2012 are used in this study. Preferred MNL and ORL models are developed and marginal effects are also calculated and compared. A majority of the variables have shown similar effects on the probability of the three different severity levels in both models. In addition, based on the Akaike information criterion, it is found that the MNL model is better than the ORL model in predicting the vehicle crash severity levels on HRGCs in this study. Therefore, the researchers recommend the use of MNL model in predicting severity levels of vehicle-rail crashes on HRGCs.

Accident and hazard prediction models for highway–rail grade crossings:a state-of-the-practice review for the USA

Highway–rail grade crossings(HRGCs)are one of the most dangerous segments of the transportation network.Every year numerous accidents are recorded at HRGCs between highway users and trains,between highway users and traffic control devices,and solely between highway users.These accidents cause fatalities,severe injuries,property damage,and release of hazardous materials.Researchers and state Departments of Transportation(DOTs)have addressed safety concerns at HRGCs in the USA by investigating the factors that may cause accidents at HRGCs and developed certain accident and hazard prediction models to forecast the occurrence of accidents and crossing vulnerability.The accident and hazard prediction models are used to identify the most hazardous HRGCs that require safety improvements.This study provides an extensive review of the state-of-the-practice to identify the existing accident and hazard prediction formulae that have been used over the years by different state DOTs.Furthermore,this study analyzes the common factors that have been considered in the existing accident and hazard prediction formulae.The reported performance and implementation challenges of the identified accident and hazard prediction formulae are discussed in this study as well.Based on the review results,the US DOT Accident Prediction Formula was found to be the most commonly used formula due to its accuracy in predicting the number of accidents at HRGCs.However,certain states still prefer customized models due to some practical considerations.Data availability and data accuracy were identified as some of the key model implementation challenges in many states across the country.

A New Accident Prediction Model for Highway-Rail Grade Crossings Using the USDOT Formula Variables

This paper presents the ZINDOT model,a methodology utilizing a zero-inflated negative binomial model with the variables used in the United States Department of Transportation(USDOT)accident prediction formula,to determine the expected accident count at a highway-rail grade crossing.The model developed contains separate formulas to estimate the crash prediction value depending on the warning device type installed at the crossing:crossings with gates,crossings with flashing lights and no gates,and crossings with crossbucks.The proposed methodology also accounts for the observed accident count at a crossing using the Empirical Bayes method.The ZINDOT model estimates were compared to the USDOT model estimates to rank the crossings based on the expected accident frequency.It is observed that the new model can identify crossings with a greater number of accidents with Gates and Flashing Lights and Crossbucks in both Illinois(data which were used to develop the model)and Texas(data which were used to validate the model).A practitioner already using the USDOT formulae to estimate expected accident count at a crossing could easily use the ZINDOT model as it employs the same variables used in the USDOT formula.This methodology could be used to rank highway-rail grade crossings for resource allocation and safety improvement.

多胎萨福克羊与哈萨克羊级进杂交后代生长性能、屠宰性能、肉品质及血液生理生化指标分析

【目的】了解天然放牧条件下多胎萨福克羊与哈萨克羊级进杂交羔羊的生长性能、屠宰性能和肉品质等,评估多胎萨福克羊对哈萨克羊的级进杂交改良效果。【方法】试验以3月龄体况、体型基本一致的多胎萨福克羊及其与哈萨克羊级进杂交F1、F2代和哈萨克公羊为研究对象,天然放牧条件下饲养,试验预试期10 d,正试期90 d。试验结束后选择接近组内平均体重羔羊各10只,屠宰前测定各试验羊体尺指标,屠宰后分别测定屠宰性能、肉品质、营养成分及血液生理生化指标。【结果】(1)多胎萨福克羊、级进杂交F1和F2代羔羊的体高、胸深、宰前活重、胴体重、屠宰率、肉骨比、眼肌面积均显著高于哈萨克羊(P<0.05);级进杂交F1代羔羊和哈萨克羊的背脂厚度、尾脂重显著高于多胎萨福克羊和级进杂交F2代羔羊(P<0.05)。(2)级进杂交F1代羔羊背最长肌水分含量显著高于多胎萨福克羊、级进杂交F2代羔羊和哈萨克羊(P<0.05);哈萨克羊背最长肌中铁、锌、镁和粗脂肪含量均显著高于多胎萨福克羊、级进杂交F1和F2代(P<0.05)。(3)多胎萨福克羊、级进杂交F1和F2代羔羊血液中白细胞数、嗜碱性粒细胞数、中性粒细胞数、嗜酸性粒细胞数、淋巴细胞数等显著高于哈萨克羊,嗜碱性粒细胞百分比、嗜酸性粒细胞百分比、血小板总数、平均血小板体积等均显著低于哈萨克羊(P<0.05)。(4)多胎萨福克羊、级进杂交F1和F2代羔羊血清中碱性磷酸酶活性显著高于哈萨克羊,总蛋白含量显著低于哈萨克羊(P<0.05);级进杂交F1代羔羊血清中谷丙转氨酶活性、铁含量均显著低于哈萨克羊(P<0.05);多胎萨福克羊血清白蛋白含量显著高于级进杂交F1、F2代和哈萨克羊(P<0.05)。【结论】天然放牧条件下,多胎萨福克羊及其级进杂交后代的产肉性能高于哈萨克羊,随着杂交代数的增加,屠宰性能明显提升、肉品质得到改善。

有轨电车通过平交路口车路协同速度控制系统

[目的]为解决有轨电车在平交路口必须降速的问题,提出一种有轨电车通过平交路口车路协同速度控制系统。[方法]分析了有轨电车平交路口运行特征;介绍了有轨电车通过平交路口车路协同速度控制系统的设计思路,以及控制算法模块的实现流程;对所提控制系统的实施效应进行分析。[结果及结论]所提控制系统通过车辆定位技术和清空区冲突检测技术,结合与路口交通信号机的通信,判定有轨电车通过路口的方式。当有轨电车获得通过路权且清空区无冲突时,采用可控实体隔离设施临时性地创建有轨电车通行的独享封闭区间,保障有轨电车安全高效地通过平交路口。所提控制系统可以实现有轨电车在信号绿灯条件下不减速通过路口。所提控制系统对于前后站台相距250 m以上的无站台平交路口适用性较好,其能提高约15%的运行速度,减少40%的区间运行能耗,同时还能减少因平交路口干扰造成站间运行时间的随机偏差。

三级综合医院全科医学科会诊现状研究

背景全科医学科诊疗范围常涉及多系统、多器官疾病,申请会诊数量大,但目前关于全科医学科会诊现状的研究仍然较少。目的收集三级综合医院全科医学科会诊相关资料,分析首都医科大学附属复兴医院全科医学科会诊现状,以提高首都医科大学附属复兴医院全科医学科会诊工作质量,为疾病的分级诊疗提供参考。方法通过医院信息系统调取首都医科大学附属复兴医院2021—2022年全科医学科提请的会诊数据,对会诊基本情况、会诊科室、会诊原因、会诊诊断、会诊意见等进行分类总结。结果2021—2022年首都医科大学附属复兴医院全科医学科共收治住院患者1441例,908例有提请会诊记录,共计发出院内会诊2269例次,执行会诊1966例次,撤销会诊303例次;已执行会诊中,男987例次,女979例次;年龄17~101岁,平均年龄(77.4±13.9)岁;共涉及31个临床科室,其中会诊次数最多的前6位科室分别为康复中心、耳鼻喉科、眼科、皮肤科、感染科及精神科;康复科、耳鼻喉科、眼科、皮肤科、感染科及精神科顺位排名第一的会诊诊断分别为功能障碍、感音神经性耳聋、白内障、皮炎、肺部感染及焦虑状态;会诊原因包括制定初始诊疗方案、调整当前诊疗方案、完善专科检查、专科协助治疗、进行专科评估等;会诊处理意见可大致分为专业评估、完善检查、明确诊断、药物治疗、临床操作、手术治疗、营养治疗、康复针灸。结论全科医学科的诊疗范围包括各个系统常见病、多发病,会诊需求量大,会诊疾病谱体现了首都医科大学附属复兴医院全科医学科的临床需求和特点,分析会诊现状,有利于弥补全科诊疗短板,提高全科会诊工作质量,向全科与专科之间的转诊迈出第一步。

基于语义特征融合的作文自动评分方法

作文自动评分技术是一种利用机器学习进行自然语言处理的技术。目前,基于深度学习的端到端模型在作文自动评分领域已经广泛使用。然而,由于端到端模型难以获取不同特征之间的相关性,因此提出一种基于语义特征融合的作文自动评分方法(TSEF)。该方法主要分为特征提取和特征融合2个阶段。特征提取阶段,使用Bert模型对输入文本进行预训练,并使用多头注意力机制对输入文本进行自训练,以补充预训练的不足;特征融合阶段,使用交叉融合方法将获取的不同特征融合,以此获得更好性能的模型。在实验中,将TSEF与许多强基线进行比较,结果表明了本文方法的有效性和稳健性。

提升高等级公路交叉口通行能力的设计与研究

近年来国家为提高国省道的通行能力逐步将道路等级提高,道路等级提高后影响车辆通行能力的主要因素是较多的交叉口设置。目前公路行业针对平面交叉口的设计缺少相应的规范和量化标准,但交叉口一直是交通事故的多发点,人车混行严重、车辆通行缓慢,大大降低了高等级公路的通行能力。结合国道208线长治境内一级公路改扩建工程案例,通过分析影响平面交叉通行能力的因素(冲突点位置及数量),采用整体式路基分割岛法、整体式路基偏转岛法、分离式路基接线法三种新的设计理念来提高道路交叉口的通行能力,从而解决传统平面交叉口通行能力差的问题。

基于交通设计理念的道路平交口交通阻塞问题的道路精细化设计

基于交通设计理念,从交通阻塞问题与特征入手,进而对交通阻塞问题成因进行研究,然后通过交叉口车道匹配设计、合理设置掉头车道、通过交通标线加强交通疏导和慢行交通一体化设计来改善交通基础设施和通行条件,以此增强道路平面交叉口的交通供给能力,从而提高交叉口通行能力,改善交叉口阻塞问题。

孔隙度对具有不均匀横截面的功能分级多孔梁的自由振动和屈曲行为的影响

本文旨在研究孔隙度对具有不均匀横截面的功能分级多孔梁的自由振动和屈曲行为的影响。一般认为材料的性能沿厚度方向变化,而梁的横截面沿其长度方向分布不均匀。三种不同的孔隙度分布包括对称分布、非对称分布和均匀分布。利用经典的梁理论和Hamilton原理推导出了问题的控制方程,并用微分求积法推导出公式。通过已知方法和分析解法对所得结果进行了验证。通过网格独立性研究,确定了最优离散化设置。利用详细的参数化分析研究了不同力学参数,包括孔隙率系数、长径比和变化截面对基频和临界屈曲载荷的影响。结果表明,材料孔隙率的增加会导致梁的屈曲能力显著降低。然而,梁的自由振动行为完全取决于其孔隙度模式。此外,孔隙呈对称分布的梁其屈曲能力和基频性能最好。

国外主要地理信息安全管理模式分析与启示

随着地理信息数据深入渗透经济社会发展各领域,其安全保密问题与流通应用之间的矛盾越发尖锐。合理借鉴国外地理信息安全管理模式,对于我国管理实践具有重要的借鉴意义。本文通过调研国外政府网站发布的法律政策及国内外相关学术文献,对比分析美国、德国、英国、日本、韩国在地理信息安全立法、体制、分级管理、市场准入、跨境流动等方面基本情况,总结地理信息安全管理的美国模式、欧洲模式和东亚模式及其特点,并指出各管理模式间的共性和差异性。同时,从管理理念、政策制度、治理体系与防控监管四个方面指出了对我国未来地理信息安全管理实践的启示。

Development of combined transitional pavement structure for urban tram track-road grade crossings

The grade crossings and adjacent pavements of urban trams are generally subjected to complex load conditions and are susceptible to damage.Therefore,in this study,a novel pavement structure between tram tracks and roads constructed using polyurethane(PU)elastic concrete and ultra-high-performance concrete(UHPC),referred to as a track-road transitional pavement(TRTP),is proposed.Subsequently,its performance and feasibility are evaluated using experimental and numerical methods.First,the mechanical properties of the PU elastic concrete are evaluated.The performance of the proposed structure is investigated using a three-dimensional finite element model,where vehicleinduced dynamic and static loads are considered.The results show that PU elastic concrete and the proposed combined TRTP are applicable and functioned as intended.Additionally,the PU elastic concrete achieved sufficient performance.The recommended width of the TRTP is approximately 50 mm.Meanwhile,the application of UHPC under a PU elastic concrete layer significantly reduces vertical deformation.Results of numerical calculations confirmed the high structural performance and feasibility of the proposed TRTP.Finally,material performance standards are recommended to provide guidance for pavement design and the construction of tram-grade crossings in the future.

基于跨理论模型的分级干预在脑梗死溶栓治疗后患者中的应用

目的探讨基于跨理论模型的分级干预在脑梗死溶栓治疗后患者中的应用效果。方法前瞻性选取2021年1月—2022年12月巨野县人民医院收治的96例行溶栓治疗的脑梗死患者为研究对象,根据随机数表法分为干预组和对照组,每组48例。对照组采用常规护理联合分级干预护理,干预组采用基于跨理论模型分级护理干预,两组均干预4周,比较两组干预前后神经受损功能情况[神经功能缺损(NIHSS)评分]、肢体功能[Fugl-Meyer运动量表(FMA)评分]、自护能力[自护能力量表(ESCA)评分]、日常生活活动能力[Barthel指数(BI)评分]以及护理风险事件发生情况。结果干预3个月后,两组NIHSS评分明显降低,FMA评分明显升高,且干预组NIHSS评分低于对照组,FMA评分高于对照组,差异有统计学意义(P<0.05);干预3个月,两组自护能力各维度评分与BI评分均高于干预前,且干预组高于对照组,差异有统计学意义(P<0.05);护理后,干预组护理风险事件发生率明显低于对照组,差异有统计学意义(P<0.05)。结论基于跨理论模型的分级干预对脑梗死溶栓治疗后患者神经功能和肢体功能改善有明显成效,可提高患者自护能力及日常生活活动能力,并减少护理干预中风险事件的发生。

我国跨境电子商务综合试验区发展创新性研究——以2021年10家评估一档综试区为样本

2022年3月,我国商务部向社会发布“2021年跨境电子商务综合试验区评估”结果,在这次评估中,杭州、宁波、青岛、上海等10个跨境电子商务综合试验区建设“成效明显”,位列评估排行“第一档”,是我国跨境电子商务综合试验区发展的先进试点和标杆城市。本文经过认真对比和深入分析,发现这10个综试区在发展的创新性方面有“共性”和“特性”两个特征,通过分析这些特征总结其发展的先进经验,以示范引领我国现阶段已经批准建立的165个跨境电子商务综合试验区不断创新发展,尤其是在管理和服务方面、制度方面、技术方面等形成“创新高地”,进而促进我国对外贸易和经济的高质量发展。

某三甲医院跨省异地患者医保结算情况及问题分析

目的随着我国各统筹区跨省异地就医联网结算工作的不断推深推进,跨省异地就医更便捷高效,分析某三甲医院跨省异地就诊患者住院情况、医保结算情况以及跨省异地就医患者所遇到的问题。方法采用回顾性调查方法,分析某三甲医院2017年1月—2021年12月跨省异地就医患者数据以及医保结算数据。结果跨省异地就医患者以中老年患者居多;平均住院日逐年递减,跨省异地就医联网结算率在逐年提高,但结算过程中仍会遇到各种问题。结论跨省异地就医工作的开展给百姓带来便利,为医保工作创造了机遇,同时患者就诊过程所遇的问题也展示了诸多挑战与压力,仍需集合多方力量,进一步简化跨省就医流程,打通信息交互障碍,让信息跑腿,患者少走路,提高跨省异地医保结算率,提升就医体验感。

八大综合经济区人力资本水平的测度、差距分解及时空演变

文章使用纵横向拉开档次法测度八大综合经济区2003—2018年的人力资本水平,采用Dagum基尼系数和核密度估计法探究人力资本的差异来源、空间演变特征。研究发现:八大综合经济区的人力资本水平都呈上升趋势,健康资本的增长速度远低于教育资本和文化资本;八大综合经济区的整体差异呈扩大趋势,区域间差异是整体差异的主要来源;各地区人力资本水平的绝对差异呈扩大趋势,存在显著的极化特征,大多数地区由多极化向单极化过渡。

有轨电车平交路口过渡段路面病害机理与对策

现代有轨电车平交路口段市政路面承受社会车辆和有轨电车两种荷载作用,介于道路与钢轨之间过渡区域的路面受力特征复杂,病害频发,成为市政道路上的薄弱部位。为探究平交路口过渡段路面的病害机理,在现场病害调研的基础上,对病害类型进行了统计与分类,同时建立了路-轨过渡区三维有限元模型,考虑社会汽车和有轨电车双重荷载,分析了轨侧路面结构的力学响应。现场调研结果表明,过渡区病害主要分布在轨侧30 cm范围,轨道附近路面沉降值大多分布在0~10 mm范围,裂缝和轨道周边材料剥落是主要的病害类型。力学分析结果表明,路面结构的承载力和强度不足、路面结构变形不协调、路面沉降下车辆荷载的冲击作用,是造成路-轨过渡区发生破坏的重要内在机理。针对病害产生机理,提出在路面结构下方铺设高模量混凝土以及在道路与轨道之间增设过渡区材料的处治对策。

相对腰大肌横截面积与椎间盘退变程度的关系

目的 分析相对腰大肌横截面积与其对应平面椎间盘退变程度的相关性。方法 回顾分析112例腰腿疼痛或麻木患者的影像资料,使用Image J软件测量患者MRI影像上L3~S1腰椎间盘的横截面积及相对应层面的腰大肌横截面积;将测得的腰大肌面积除以同平面腰椎间盘的面积,计算相对腰大肌横截面积,椎间盘退变程度以Pfirrmann标准分级进行评价,分别比较同层面不同腰椎间盘的退变程度间的相对腰大肌横截面积间的差异,分析同平面腰椎间盘退变程度与相对腰大肌横截面积的相关性,并分析探究相对腰大肌横截面积的影响因素。结果 同一层面上,腰椎间盘的不同退变程度间相对腰大肌横截面积的差异均有统计学意义。L_(5)/S_(1)、L_(4)/L_(5)、L_(3)/L_(4)三个平面上,腰椎间盘退变程度与同层面的相对腰大肌横截面积均存在相关性,相关系数如下:-0.406,-0.538,-0.575,P均<0.001;腰椎间盘退变程度是相对腰大肌横截面积的独立影响因素。结论 腰椎间盘退变程度与相对腰大肌横截面积呈负相关;腰椎间盘的退变是腰大肌肌肉萎缩的危险因素。