A Mixed User‐Equilibrium and System‐Optimal Traffic Flow for Connected Vehicles Stated as a Complementarity Problem

Connected vehicles (CVs), be they autonomous vehicles or a fleet of cargo carriers or Uber, are a matter of when they become a reality and not if. It is not unreasonable to think that CV technology may have a far‐reaching impact, even to the genesis of a completely new traffic pattern. To this end, the literature has yet to address the routing behavior of the CVs, namely traffic assignment problem (TAP) (perhaps it is assumed, they ought to follow the traditional shortest possible paths, known as user equilibrium [UE]). It is possible that real‐time data could be derived from the vehicles’ communications that in turn could be used to achieve a better traffic circulation. In this article, we propose a mathematical formulation to ensure the CVs are seeking the system optimal (SO) principles, while the remainder continue to pursue the old‐fashioned UE pattern. The model is formulated as a nonlinear complementarity problem (NCP). This article contributes to the literature in three distinct ways: (i) mathematical formulation for the CVs’ routing, stated as a mixed UE‐SO traffic pattern, is proposed; (ii) a variety of realistic features are explicitly considered in the solution to the TAP including road capacity, elastic demand, multiclass and asymmetric travel time; and (iii) formal proof of the existence and uniqueness of the solutions are also presented. The proposed methodology is applied to the networks of Sioux‐Falls and Melbourne.     

城市公交车对双车道混合交通流的影响

城市道路上的车流主要是公交车和小汽车混合流,而一般交通流理论都是以小汽车流为对象进行研究和建模。基于运动波理论和线性元胞自动机模型,本文提出了一种宏观与微观空间表现尺度相结合的双车道混合交通流组合建模方法分析。     

Random Process Model for Urban Traffic Flow Using a Wavelet‐Bayesian Hierarchical Technique

Abstract: The existing well‐known short‐term traffic forecasting algorithms require large traffic flow data sets, including information on current traffic scenarios to predict the future traffic conditions. This article proposes a random process traffic volume model that enables estimation and prediction of traffic volume at sites where such large and continuous data sets of traffic condition related information are unavailable. The proposed model is based on a combination of wavelet analysis (WA) and Bayesian hierarchical methodology (BHM). The average daily “trend” of urban traffic flow observations can be reliably modeled using discrete WA. The remaining fluctuating parts of the traffic volume observations are modeled using BHM. This BHM modeling considers that the variance of the urban traffic flow observations from an intersection vary with the time‐of‐the‐day. A case study has been performed at two busy junctions at the city‐centre of Dublin to validate the effectiveness of the strategy.     

Evaluation of Information Applications of a Self‐Organizing Distributed Traffic Information System for a Large‐Scale Real‐World Traffic Network

Abstract: This article presents an evaluation of the system performance of a proposed self‐organizing, distributed traffic information system based on vehicle‐to‐vehicle information‐sharing architecture. Using microsimulation, several information applications derived from this system are analyzed relative to the effectiveness and efficiency of the system to estimate traffic conditions along each individual path in the network, to identify possible incidents in the traffic network, and to provide rerouting strategies for vehicles to escape congested spots in the network. A subset of vehicles in the traffic network is equipped with specific intervehicle communication devices capable of autonomous traffic surveillance, peer‐to‐peer information sharing, and self‐data processing. A self‐organizing traffic information overlay on the existing vehicular roadway network assists their independent evaluation of route information, detection of traffic incidents, and dynamic rerouting in the network based both on historical information stored in an in‐vehicle database and on real‐time information disseminated through intervehicle communications. A path‐based microsimulation model is developed for these information applications and the proposed distributed traffic information system is tested in a large‐scale real‐world network. Based on simulation study results, potential benefits both for travelers with such equipment as well as for the traffic system as a whole are demonstrated.     

Development of a Data‐Driven Framework for Real‐Time Travel Time Prediction

Travel time prediction is one of the most important components in Intelligent Transportation Systems implementation. Various related techniques have been developed, but the efforts for improving the applicability of long‐term prediction in a real‐time manner have been lacking. Existing methods do not fully utilize the advantages of the state‐of‐the‐art cloud system and large amount of data due to computation issues. We propose a new prediction framework for real‐time travel time services in the cloud system. A distinctive feature is that the prediction is done with the entire data of a road section to stably and accurately produce the long‐term (at least 6‐hour prediction horizon) predicted value. Another distinctive feature is that the framework uses a hierarchical pattern matching called Multilevel k‐nearest neighbor (Mk‐NN) method which is compared with the conventional k‐NN method and Nearest Historical average method. The results show that the method can more accurately and robustly predict the long‐term travel time with shorter computation time.     

略论城市中心区交通改善策略与道路交叉口交通改善设计

本文针对我国城市中心区交叉口存在的交通问题,在分析交通特性的基础上,提出中心区交叉口宏观和微观相结合改善思路,从交通需求管理、道路资源的整合以及交通与土地利用关系三个方面提出中心区宏观交通改善策略,微观上从网络系统、交叉口以及交叉口周边土地利用三个方面提出相应的改善措施。     

Hybrid Demand‐Driven and Cyclic Timetabling Considering Rolling Stock Circulation for a Bidirectional Railway Line

For dense railway lines, timetables are commonly designed periodically to provide regular services. However, such timetables may lead to many low‐occupancy departures and make it inefficient to a railway company. We combine the features of periodic timetabling with those of demand‐responsive timetabling design for a bidirectional rail transit line considering rolling stock circulation. A mixed‐integer programming model with the objective of minimizing total passenger waiting time and weighted total train travel time is formulated and a three‐phase heuristic algorithm is developed. Five performance indicators, namely, total train travel time, passenger average waiting time, event time deviation, event frequency deviation, and train connection time are introduced to evaluate the performance of the model. A case study on Jinshan railway corridor in Shanghai demonstrates that the proposed demand responsive periodic timetabling model can reduce passengers’ waiting time and keep periodicity in the meantime with short computational time     

An Automated Surveying and Marking System for Continuous Setting‐out of Tunnels

Setting‐out is a crucial and frequently repeated process in construction and civil engineering. It is carried out by qualified operators who, making use of surveying stations, identify reference points to guide workers in their tasks. In this paper, we focus on the particular case of setting‐out road/train tunnels and propose a system that automatically performs the setting‐out operation of the tunnel section to be perforated. The presented system, called Tunnel Continuous Setout (TCS), integrates a scanning device that surveys the excavation front and a laser projector that continuously displays the actual tunnel section computed as the intersection between the surveyed terrain and the planned tunnel section. Thus, the topographer intervention is only required for the precise positioning of the TCS device at the beginning of each working stretch, which depends on the operational range of its components (limited to 25 meters in the current implementation). A prototype of the TCS system has been employed in a real construction site proving its benefits and advantages with respect to the traditional setting‐out techniques.     

Spreading Patterns of Malicious Information on Single‐Lane Platooned Traffic in a Connected Environment

The connected vehicle can be easily attacked by cyber threats due to its communication through the wireless network in an open‐access environment. But very few studies have paid attention to the spreading of malicious information such as denial of service, message delay/replay, and eavesdropping generated by cyberattacks. To this end, this article introduces an analytical model, named vehicular malicious information propagation (VMIP), which integrates a classical epidemic model through two‐layer system structure, in which the upper layer describes the malicious information spreading and the lower describes the traffic flow dynamics. The proposed VMIP model is designated for platooned (one‐lane, particularly) traffic. Numerical experiments show the proposed model can efficiently describe the interactions between traffic dynamics and malicious information spreading; and the information propagation highly depends on traffic flow patterns. This article is expected to contribute to a better understanding of the impacts of cyberattacks on traffic and lays a foundation for future development of control strategies on mitigating the disastrous effects of cyberattacks.     

Seismic Data‐Driven Identification of Linear Models for Building Structures Using Performance and Stabilizing Objectives

A two‐stage dual‐objective structural identification method is presented in this article. The complexity of the identification of story‐level physical models for large‐scale building structures is first addressed through a comparative study. A stiffness variation‐based stabilizing objective is proposed to be necessarily incorporated into iterative optimization with the classical performance objectives to improve the model feasibility, and an area‐type evaluation index is subsequently proposed for the stopping criteria. Accordingly, a two‐stage differential evolution‐based dual‐objective optimization framework is presented for the computation of Pareto fronts for nondominated candidate solutions. Then, the proposed method is investigated using two illustrative examples, including a nine‐story benchmark structure, and a real‐world seven‐story reinforced concrete structure. A series of condensed models are identified from the nondominated solutions on the Pareto front. The prediction performance of the single‐objective optimal model and the dual‐objective acceptable models is compared using the overall discrepancies of acceleration, interstory drift, and modal properties, within both estimation and validation cases. Incorporation of the noise effect into the method is finally studied and discussed.     

国内企业小型挖掘机开发设计及制作流程控制策略探讨

1 对小型挖掘机市场的认识 　　目前我国小型专业挖掘机的市场“保有量“及“产销量“与发达国家相比相差甚远,这当然与中国发展国情不无关系,但近几年上升态势迅猛.15吨以下的小型挖掘机2003年至2006年产销量增势图如图1所示.……     

随机车流下连续梁桥冲击系数谱实测与分析

对1座连续梁桥在开放交通下的动响应进行了现场实测和分析。对试验桥的调查、测试和分析主要包括:路面粗糙度实测及功率谱密度分析、自振特性测试与分析、开放交通下的交通荷载观测以及相应的桥梁动位移和加速度实测。为了根据实测桥梁动位移响应确定冲击系数,采用低通Butterworth滤波器对实测动位移响应的动力部分进行滤除而保留了静力极值。此外,研究了冲击系数与车质量、车速之间的关系,采用K-S检验法分别按极值Ⅰ型分布类型对实测冲击系数进行了分布拟合检验,并基于统计方法确定了该桥的冲击系数,最后与各国规范确定的冲击系数进行了对比。结果表明:冲击系数随着车质量的增加而减小,冲击系数随着车速的增加在一个较宽的范围内整体上逐渐增大,实测冲击系数谱基本上服从极值Ⅰ型分布,采用统计方法确定的冲击系数小于很多国家规范确定值。     

Structural Disparities of Urban Traffic in Southern California: Implications for Vehicle‐Related Air Pollution Exposure in Minority and High‐Poverty Neighborhoods

Abstract: Structural inequalities provide an important context for understanding and responding to the impact of high traffic densities on disadvantaged neighborhoods. Emerging atmospheric science and epidemiological research indicates hazardous vehicle‐related pollutants (e.g., diesel exhaust) are highly concentrated near major roadways, and the prevalence of respiratory ailments and mortality are heightened in these high‐traffic corridors. This article builds on recent findings that low‐income and minority children in California disproportionately reside in high‐traffic areas by demonstrating how the urban structure provides a critical framework for evaluating the causes, characteristics, and magnitude of traffic, particularly for disadvantaged neighborhoods. We find minority and high‐poverty neighborhoods bear over two times the level of traffic density compared to the rest of the Southern California region, which may associate them with a higher risk of exposure to vehicle‐related pollutants. Furthermore, these areas have older and more multifamily housing, which is associated with higher rates of indoor exposure to outdoor pollutants, including intrusion of motor vehicle exhaust. We discuss the implications of these patterns on future planning and policy strategies for mitigating the serious health consequences of exposure to vehicle‐related air pollutants.     

Effect of a novel temperature‐controlled laminar airflow device on personal breathing zone aeroallergen exposure

Temperature‐controlled laminar airflow improves symptoms in atopic asthmatics, but its effects on personal allergen exposure are unknown. We aimed to evaluate its effects on personal cat allergen and particulate exposures in a simulated bedroom environment. Five healthy volunteers lay under an active and an inactive temperature‐controlled laminar airflow device for 175 min, in a simulated bedroom containing bedding from a cat owner. Total airborne particles (≥0.5 – ≥10 μm diameter) were quantified with a laser particle counter. Airborne allergen was sampled with Institute of Occupational Medicine filters. Inhaled exposure was sampled with nasal air samplers. Allergen‐containing particles were quantified by immunoassay. Treatment reduced total airborne particles (>0.5 μm diameter) by >99% (P < 0.001) and reduced airborne allergen concentration within the breathing zone (ratio of median counts = 30, P = 0.043). Treatment reduced inhaled allergen (ratio of median counts = 7, P = 0.043). Treatment was not associated with a change in airborne allergen concentration outside of the breathing zone (P = 0.160). Temperature‐controlled laminar airflow treatment of individuals in an allergen‐rich experimental environment results in significant reductions in breathing zone allergenic and non‐allergenic particle exposure, and in inhaled cat allergen exposure. These findings may explain the clinical benefits of temperature‐controlled laminar airflow.     

Wind tunnel test and field measurement study of wind effects on a 600‐m‐high super‐tall building

Ping An Finance Center with a height of 600 m and 118 storeys, located in Shenzhen, is currently the second tallest building in China. This paper presents a comprehensive study of wind effects on the supertall building through wind tunnel testing and field measurement. The wind‐induced loads and pressures on the skyscraper were measured by high‐frequency force balance technique and synchronous multipressure sensing system, respectively. In the wind tunnel study, a whole range of characteristic properties, including mean and r.m.s force coefficients, power spectral densities, coherences, correlations, and phase‐plane trajectories, wind‐induced displacement, and acceleration responses were presented and discussed. In addition, a field measurement study of the dynamic responses of Ping An Finance Center was conducted during a tropical cyclone, which aimed to verify the design assumptions and further the understanding of the dynamic properties and performance of the 600‐m‐high supertall building, including natural frequencies, damping ratios, and wind‐induced structural responses. Then, the serviceability of the skyscraper is assessed on the basis of the experimental results and field measurements. The outcomes of this combined model test and field measurement study are expected to be useful for the wind‐resistant design of future supertall buildings.     

Effect of filler material on local and global behaviour of buckling‐restrained braces

The nonlinear response of buildings has attracted a tremendous amount of attention in recent years. Braces, as lateral force‐resisting elements of a structure, are designed to not only react in the elastic region, but also to exhibit nonlinear response beyond the elastic limit. However, buckling in compression drastically degrades the performance of braces under earthquake loading. Buckling restrained braces (BRBs) have been evolved into very effective systems for severe seismic applications. They prevent buckling in compression through the encasing of core steel into a steel tube and confining infill concrete. The effect of infill material is investigated in this research through the use of experimental tests. Filler material may be concrete, grout or mortar, as well as granular material such as compacted aggregate. Moreover, lightweight concrete or lean concrete may be utilized as filler to reduce the overall structural weight. Furthermore, the need for unbonding material may not arise when sand and gravel mixture is used. Nevertheless, the strength of the aggregate should be such that no buckling or strength deterioration is observed. Parametric studies on BRB characteristics are carried out in this research. Results of cyclic loading tests are then provided for individual cases to characterize the effect of response parameters of BRB assemblages. Copyright © 2009 John Wiley & Sons, Ltd.     

The Effect of Overbank Flow in a Meandering River on its Conveyance and the Transport of Graded Sediments

A large-scale model hydraulic study of inbank and over-bank river flow, using a regular sinuous river channel with a mobile bed, was carried out in the Flood Channel Facility at HR Wallingford, UK. The selected sediment had a wide range of particle sizes present over the 'fine sand to coarse sand'range. Flow velocity, local and global sediment transport rates, and channel conveyance were all measured. The resulting bed forms were determined and used to explain the secondary circulation in the sinuous channel as well as the size sorting of the sediment. The paper gives an early overview of this major project.     

Identification of damping ratio and its influences on wind‐ and earthquake‐induced effects for large cooling towers

Standard 5% damping ratio for high‐rise concrete structures is generally used for dynamic analysis under the action of wind and earthquakes in the existing cooling tower regulations and researches. But considering the unique configuration and material attributes of large cooling towers, the actual damping ratio must be far smaller than the recommended. However, only a few field measurements of damping ratio for large cooling towers have been conducted; neither are there thorough investigation into the qualitative and quantification of wind and seismic effects under different damping ratio. To fill this gap, field measurements of a large cooling tower standing 179 m in northwestern China was performed and acceleration vibration signals at representative positions of the tower under ambient excitation were obtained. The vibration signals were preprocessed combining random decrement technique and natural excitation technique. Three pattern recognition methods (auto‐regressive and moving mean model, Ibrahim time domain, and spare time domain (STD)) were applied to analyze the frequencies, damping ratios, and modes of vibration for the first 10 order modes. Following the line of thought of modal combination, the equivalent synthetic damping ratio was derived. Under 5 damping ratios (0.5%, 1%, 2%, 3%, and 5%), a comparative analysis on the dynamic responses of the cooling tower to wind and single seismic loading by using full transient method was performed. On this basis, the patterns of influence of damping ratio on wind‐induced vibration, wind vibration coefficient, and time history and extrema of seismic responses were extracted. Finally, different combinations of dead weight, wind, temperature in winter, sunshine duration, and seismic intensity and those of accidental seismic effects (8 working conditions) were considered, using equivalent synthetic damping ratio and standard damping ratio. Thus, the most unfavorable working conditions were identified under actual and standard damping ratios for the large cooling tower. Our research findings provide reference for determining the value of damping ratio in large cooling towers and deepening the understanding on the influence mechanism of damping ratio.     

Experimental study on a novel replaceable yielding‐based energy dissipater for rocking and seesaw buildings

The use of energy dissipaters for creation of earthquake‐resilient buildings has been paid more and more attention in recent years, and some newly developed structural fuses or dampers have been proposed to be employed in rocking and seesaw buildings. In this study, a new type of yielding‐based dampers, called curved‐yielding‐plates energy dissipater (CYPED), is introduced. CYPEDs are installed at the bottom of rocking or seesaw building's circumferential columns at the lowest story and have hysteretic behavior in their deformation occurring in vertical direction. The initial curvature of the yielding plates prevents them from buckling and gives the device a smooth force–deformation behavior. First, by performing a set of cyclic tests on three specimens of CYPED, their hysteretic force–displacement behavior was investigated. Then, to show the efficiency of this energy dissipating device in reducing the seismic response of buildings, they were employed numerically as multilinear plastic springs in the computer models of a sample seesaw steel building, and a series of nonlinear time history analysis (NLTHA) were performed on both seesaw building and its conventional counterpart. Results of NLTHA show that the proposed seesaw structural system equipped with appropriate CYPEDs not only gives the building a longer natural period, leading to lower seismic demand, but also leads to remarkable energy dissipation capacity in the building structure at base level and, therefore, keeping the seismic drifts in elastic range in all stories of the building. In this way, the building structure does not need any major repair work, even after a large earthquake, while the conventional building suffers from heavy damage and is not usable after the earthquake.