Research on visual differences of exits of different grades of tunnels based on machine learning

Tunnels are vital in connecting crucial transportation hubs as transportation infrastructure evolves.Variations in tunnel design standards and driving conditions across different levels directly impact driver visual perception and traffic safety.This study employs a Gaussian hybrid clustering machine learning model to explore driver gaze patterns in highway tunnels and exits.By utilizing contour coefficients,the optimal number of classification clusters is determined.Analysis of driver visual behavior across tunnel levels,focusing on gaze point distribution,gaze duration,and sweep speed,was conducted.Findings indicate freeway tunnel exits exhibit three distinct fixation point categories aligning with Gaussian distribution,while highway tunnels display four such characteristics.Notably,in both tunnel types,65%of driver gaze is concentrated on the near area ahead of their lane.Differences emerge in highway tunnels due to oncoming traffic,leading to 13.47%more fixation points and 0.9%increased fixation time in the right lane compared to regular highway tunnel conditions.Moreover,scanning speeds predominantly fall within the 0.25-0.3 range,accounting for 75.47%and 31.14%of the total sweep speed.

Pedestrian flow through exit:Study focused on evacuation pattern

Experiments are conducted on the evacuation rate of pedestrians through exits with queued evacuation pattern and random evacuation pattern. The experimental results show that the flow rate of pedestrians is larger with the random evacuation pattern than with the queued evacuation pattern. Therefore, the exit width calculated based on the minimum evacuation clear width for every 100 persons, which is on the assumption that the pedestrians pass through the exit in one queue or several queues, is conservative. The number of people crossing the exit simultaneously is greater in the random evacuation experiments than in the queued evacuation experiments, and the time interval between the front row and rear row of people is shortened in large-exit conditions when pedestrians evacuate randomly. The difference between the flow rate with a queued evacuation pattern and the flow rate with a random evacuation pattern is related to the surplus width of the exit, which is greater than the total width of all accommodated people streams. Two dimensionless quantities are defined to explore this relationship. It is found that the difference in flow rate between the two evacuation patterns is stable at a low level when the surplus width of the exit is no more than 45% of the width of a single pedestrian stream. There is a great difference between the flow rate with the queued evacuation pattern and the flow rate with the random evacuation pattern in a scenario with a larger surplus width of the exit. Meanwhile, the pedestrians crowd extraordinarily at the exit in these conditions as well, since the number of pedestrians who want to evacuate through exit simultaneously greatly exceeds the accommodated level. Therefore, the surplus width of exit should be limited especially in the narrow exit condition, and the relationship between the two dimensionless quantities mentioned above could provide the basis to some extent.

Logit-based exit choice model of evacuation in rooms with internal obstacles and multiple exits

A logit-based discrete choice model is proposed to study the exit choice behaviour of evacuees in rooms with internal obstacles and multiple exits. Several factors influencing the exit choice behaviour, including the information obtained by evacuees, the tendency of following others, the visibility and familiarity of exits and the physical conditions of nearby exits, are considered. Evacuees are allowed to re-select their target exits for minimizing the perceived disutility during evacuation process. Numerical results from applying the model to cellular automata simulation of evacuation are presented and the effects of some model parameters on evacuation time are investigated.

Exit selection strategy in pedestrian evacuation simulation with multi-exits

A mixed strategy of the exit selection in a pedestrian evacuation simulation with multi-exits is constructed by fusing the distance-based and time-based strategies through a cognitive coefficient, in order to reduce the evacuation imbalance caused by the asymmetry of exits or pedestrian layout, to find a critical density to distinguish whether the strategy of exit selection takes effect or not, and to analyze the exit selection results with different cognitive coefficients. The strategy of exit selection is embedded in the computation of the shortest estimated distance in a dynamic parameter model, in which the concept of a jam area layer and the procedure of step-by-step expending are introduced. Simulation results indicate the characteristics of evacuation time gradually varying against cognitive coefficient and the effectiveness of reducing evacuation imbalance caused by the asymmetry of pedestrian or exit layout. It is found that there is a critical density to distinguish whether a pedestrian jam occurs in the evacuation and whether an exit selection strategy is in effect. It is also shown that the strategy of exit selection has no effect on the evacuation process in the no-effect phase with a low density, and that evacuation time and exit selection are dependent on the cognitive coefficient and pedestrian initial density in the in-effect phase with a high density.

Effect of a static pedestrian as an exit obstacle on evacuation

Building exit as a bottleneck structure is the last and the most congested stage in building evacuation.It is well known that obstacles at the exit affect the evacuation process,but few researchers pay attention to the effect of stationary pedestrians(the elderly with slow speed,the injured,and the static evacuation guide)as obstacles at the exit on the evacuation process.This paper explores the influence of the presence of a stationary pedestrian as an obstacle at the exit on the evacuation from experiments and simulations.We use a software,Pathfinder,based on the agent-based model to study the effect of ratios of exit width(D)to distance(d)between the static pedestrian and the exit,the asymmetric structure by shifting the static pedestrian upward,and types of obstacles on evacuation.Results show that the evacuation time of scenes with a static pedestrian is longer than that of scenes with an obstacle due to the unexpected hindering effect of the static pedestrian.Different ratios of D/d have different effects on evacuation efficiency.Among the five D/d ratios in this paper,the evacuation efficiency is the largest when d is equal to 0.75D,and the existence of the static pedestrian has a positive impact on evacuation in this condition.The influence of the asymmetric structure of the static pedestrian on evacuation efficiency is affected by D/d.This study can provide a theoretical basis for crowd management and evacuation plan near the exit of complex buildings and facilities.

Exit strategies in inflammatory bowel disease:Looking beyond antitumor necrosis factors

The long-term management of patients with inflammatory bowel disease(IBD)is still a matter of debate,and no clear guidelines have been issued.In clinical practice,gastroenterologists often have to deal with patients in prolonged remission after immunomodulatory or immunosuppressive therapies.When planning an exit strategy for drug withdrawal,the risk of disease relapse must be balanced against the risk of drug-related adverse events and healthcare costs.Furthermore,there is still a dearth of data on the withdrawal of novel biologics,such as the anti-α4β7 integrin antibody(vedolizumab)and anti-IL12/23 antibody(ustekinumab),as well as the small molecule tofacitinib.Models for estimating the risk of disease relapse and the efficacy of retreatment should be evaluated according to the patient's age and IBD phenotype.These models should guide clinicians in programming a temporary drug withdrawal after discussing realistic outcomes with the patient.This would shift the paradigm from an exit strategy to a holiday strategy.

Consequences of Exits from Political Unions on Dividend Policy: The Case of Ethiopian Split

This paper examines the consequences of exits from political unions or the split of countries on dividend policy decision,taking the Ethiopian split as a practical case,considered as a major factor in the increase of political tension with Eritrea especially after the secession,that led to the increase in successive political conflicts and dispute over the past years till now.This paper studies the impacts of political conflicts that have been companied with split to this day especially during the period between 2010 and 2019,using a database of six companies from different sectors,from Ethiopia.The results show that the political conflicts such as split have a direct impact on the dividend policy.

Consequences of Exits from Political Unions on Leverage: The Case of Sudan Split

This paper examines the consequences of exits from political unions and the split of countries on capital structure decision especially the leverage,taking Sudan split(2011)as a practical case.Where the split between the two countries presents a challenge to companies in Sudan,especially they have not faced such a situation before in their businesses.This paper studies the impacts of the split on the capital structure during the period before and after the split,between 2008 and 2015,using a database of five different companies from different sectors,from Sudan.A regression model was adopted to study the impact of the split on the variables in order to analyze the variation in the ratios before and after the split.The results show that the political decisions such as split have a lot of consequences on the capital structure.

Exit problem of stochastic SIR model with limited medical resource

Nonlinearity and randomness are both the essential attributes for the real world,and the case is the same for the models of infectious diseases,for which the deterministic models can not give a complete picture of the evolution.However,although there has been a lot of work on stochastic epidemic models,most of them focus mainly on qualitative properties,which makes us somewhat ignore the original meaning of the parameter value.In this paper we extend the classic susceptible-infectious-removed(SIR)epidemic model by adding a white noise excitation and then we utilize the large deviation theory to quantitatively study the long-term coexistence exit problem with epidemic.Finally,in order to extend the meaning of parameters in the corresponding deterministic system,we tentatively introduce two new thresholds which then prove rational.

The asymptotic relation between the first crossing point and the last exit time of Gaussian order statistics sequences

In this paper,we study the asymptotic relation between the first crossing point and the last exit time for Gaussian order statistics which are generated by stationary weakly and strongly dependent Gaussian sequences.It is shown that the first crossing point and the last exit time are asymptotically independent and dependent for weakly and strongly dependent cases,respectively.The asymptotic relations between the first crossing point and the last exit time for stationary weakly and strongly dependent Gaussian sequences are also obtained.

机构投资者退出威胁能有效抑制高管机会主义减持吗?

本文以2007—2020年中国A股上市公司为研究样本,考察机构投资者退出威胁对高管机会主义减持行为的影响及作用机制。研究发现,机构投资者退出威胁能够有效抑制高管机会主义减持行为,具有显著的治理效应。机构投资者退出威胁有效降低了股价波动和股票错误定价,从而显著抑制了高管机会主义减持。环境不确定性和管理层自利性越强,则机构投资者退出威胁对高管机会主义减持的抑制效应越弱。进一步分析发现,上市公司机构投资者为交易型、发生股权质押以及产权性质为非国有企业时,机构投资者退出威胁对高管机会主义减持的影响更强;而且机构投资者退出威胁治理效应产生了积极的后果,显著抑制了高管减持寻租,提升了企业价值,降低了高管减持时的择机性。

Analysis of Interchange Exit Safety Technology

In order to improve the safety of the exit of expressway interchanges,the main problems and influencing factors of interchange exits are analyzed according to the number of traffic accidents at expressway interchange exits in China.Some suggestions and countermeasures are then put forward from the aspect of safety technology for future reference.

机构投资者退出威胁与企业绿色创新

提高企业绿色创新水平是实现高质量发展的重要途径。基于2010—2020年沪深A股上市公司数据,实证检验机构投资者退出威胁对企业绿色创新的影响。研究发现,机构投资者退出威胁能够推动企业绿色创新;而且,以机构投资者持股比例为门槛变量,机构投资者退出威胁对企业绿色创新的影响存在单门槛效应,当机构投资者持股比例超过门槛值后,退出威胁的正向作用得以显现。进一步的路径分析表明,机构投资者退出威胁能够促使企业加大研发投入、积极履行环境责任。此外,在机构投资者为抗压型、企业为非国有性质或重污染行业的情况下,机构投资者退出威胁的绿色创新赋能效应更显著。

Research on Traffic Safety at Tunnel Entrance and Exit

Highway tunnel entrances have a high rate of expressway traffic accidents.In this paper,the reasons for the high incidence of traffic accidents at highway tunnel entrances are analyzed in detail,and corresponding solutions are proposed,hoping to provide some reference to relevant parties.

盾构隧道进出洞施工渗漏诱发结构倒塌试验研究

为明确隧道进出洞施工时因渗漏而诱发的结构倒塌发展过程,设计并开展缩尺模型试验。根据相似关系设计模型试验,制作模型土体与模型盾构隧道。参考实际进出洞施工渗漏事故案例,触发模型盾构隧道渗漏,在模型箱内重现隧道结构倒塌的全过程,并观测事故发展过程中的地层响应、隧道外部土压力变化、隧道倒塌发展过程。通过分析隧道进出洞施工中不同位置发生渗漏后结构的倒塌响应,对比不同位置渗漏对隧道进出洞施工致灾发展过程的影响。试验研究发现:1)隧道进出洞施工发生渗漏后,外部土体由于渗流侵蚀产生不稳定土洞,土洞经历了形成—失稳—再现的循环过程;2)隧道结构倒塌是由不稳定土洞失稳坠落冲击隧道结构导致的;3)隧道顶部和腰部2种不同位置渗漏后外部土体侵蚀发展的本质相同,但是不同渗漏位置产生的土洞形状有明显差异,导致最终隧道倒塌位置有所差异。

企业社会责任的“责任”究竟是什么

企业社会责任是从企业主体性出发,在保持好组织绩效的基础上,对员工和在地社区负责,并传递、展示和倡导积极的社会公共价值。企业社会责任是“有限”责任。企业是一种具有特殊性质的组织形式,负担的社会责任也必须与企业组织的固有特征以及特定企业的目标与使命相关。社会也应当适当降低对企业社会责任的预期,大致界定企业与其他社会组织的边界,防止企业承担无限责任。企业社会责任的履行应当寻求内生性的约束机制。传统的外部监管机制成本巨大,且不可能消除监管漏洞。企业社会责任履行机制的设计应当更多地考虑利用企业的存续高度依赖于其他社会成员合作的特性,以社会信用机制提高企业的合作成本与自律成本,形成有效约束力。为克服企业社会责任的履行困境,应改变观念,并从内生性约束角度规约企业行为,而不是通过无节制地加强监管或惩罚去实现,那样做只会耗费更多的社会成本却收效甚微。管理者必须做出根本的改变,理解企业组织和管理者自身的存在意义,拒绝功利主义的诱惑,敢于承担企业的“有限”社会责任,不负企业使命。

高速列车突出隧道过程中横风效应研究

为研究横风效应对突然驶出隧道过程中高速列车气动特性的影响,基于列车流场的三维、可压缩性的非定常特性,建立隧道-列车-横风三维数值模模型,研究横风效应对驶出隧道过程中高速列车流场分布和列车表面压力的影响,揭示列车气动荷载变化机理。通过与动模型试验结果进行对比,验证数值模拟的合理性。研究结果表明:横风下列车驶出隧道过程中流场分布具有显著空间效应,受列车与隧道相互作用影响,隧道出口附近流场具有明显非定常特性;相较于无风情形,横风下列车底部压力变化幅值增大60%,列车迎风面、顶部压力变化幅值分别增大38.1%和28.6%,背风面压力变化幅值差异为4.8%,背风面压力分布受横风影响最小;横风效应导致列车气动特性发生显著变化,气动荷载变化幅值远比无风情形的大,无风时尾车横向力、升力变化幅值最大,横风作用下头车横向力变化幅值最大,倾覆风险最大。

隧道类型对驶出隧道高速列车横风效应影响研究

基于横风下高速列车流场的非定常特性,建立横风-隧道-列车数值模型进行计算,研究隧道类型对横风下高速列车驶出过程中气动压力、流场特性和列车气动荷载的影响.结果表明:隧道出口处气动压力受隧道类型影响最为显著,单线隧道列车迎、背风侧气动压力变化幅值比双线隧道气动压力变化幅值分别大15.7%和22.6%;在列车类型、车速和横风条件相同情况下,阻塞比是导致单线隧道气动压力较大的根本原因;列车背风侧分离涡形成位置到头车鼻尖距离相同,但双线隧道列车背风侧流场偏移程度更大;头车与中车周围流场分布规律基本相同,受隧道类型影响较小,而尾车流场分布特性受隧道类型影响较大.尾车气动荷载对隧道类型更加敏感,双线隧道尾车横向力系数、升力系数变化幅值分别比单线隧道大27.3%和7.1%.当高速列车在横风环境中驶出隧道时,建议考虑隧道类型对列车气动性能的影响.

职业教育“双师型”教师资格认定的“结”与“解”

“双师型”教师是推进职业教育高质量发展的第一资源,是加速实现职业教育现代化的重要力量。我国职业教育“双师型”教师经过了概念内涵逐步清晰、教师数量逐年增多、资格认定标准逐渐完善、相关法律制度体系日趋严密的发展历程。“双师型”教师资格的取得与丧失,事关教师切身利益,关乎职业教育师资队伍整体素质与建设水平。建立完备的职业教育“双师型”教师资格准入退出机制,将为建设一支符合中国实际、体现职教特色的“双师型”教师队伍,提供充足的制度支持和法律保障。为此,需要分层分类细化标准要求,建立健全认证与评价机制,强化彰显职业教育跨界属性,补强优化法律制度保障。

土木工程学科博士研究生培养质量提升的体系构建研究

高层次人才培养和创新创造是研究生教育的重要使命。近期,多部门联合发文要求加快新时代研究生教育改革。只有按照“四个面向”为国家破解“卡脖子”技术,取得原创新科技成果才能成为国家战略科技力量。围绕“立德树人、服务需求、提高质量、追求卓越”的新发展思路,结合同济大学深化综合改革方案和建设世界一流大学的总体需要,对于土木工程学科博士研究生培养质量提升体系的构建进行研究,进一步突显人才培养的质量与内涵,着重强调课程和培养中间环节的质量保证和过程监督、研究生培养分流退出机制、学院和导师的主体责任,构建闭环管理体系以提升博士研究生培养质量。