Guided Crowd Evacuation:Approaches and Challenges

Evacuation leaders and/or equipment provide route and exit information for people and guide them to the expected destinations, which could make crowd evacuation more efficient in case of emergency. The purpose of this paper is to provide an overview of recent advances in guided crowd evacuation. Different guided crowd evacuation approaches are classified according to guidance approaches and technologies. A comprehensive analysis and comparison of crowd evacuation with static signage, dynamic signage, trained leader, mobile devices, mobile robot and wireless sensor networks are presented based on a single guidance mode perspective. In addition, the different evacuation guidance systems that use high-tech means such as advanced intelligent monitoring techniques, AI techniques, computer technology and intelligent inducing algorithms are reviewed from a system’s perspective. Future researches in the area of crowd evacuation are also discussed.

Four Wheel Independent Drive Electric Vehicle Lateral Stability Control Strategy

In this paper,a kind of lateral stability control strategy is put forward about the four wheel independent drive electric vehicle.The design of control system adopts hierarchical structure.Unlike the previous control strategy,this paper introduces a method which is the combination of sliding mode control and optimal allocation algorithm.According to the driver’s operation commands(steering angle and speed),the steady state responses of the sideslip angle and yaw rate are obtained.Based on this,the reference model is built.Upper controller adopts the sliding mode control principle to obtain the desired yawing moment demand.Lower controller is designed to satisfy the desired yawing moment demand by optimal allocation of the tire longitudinal forces.Firstly,the optimization goal is built to minimize the actuator cost.Secondly,the weighted least-square method is used to design the tire longitudinal forces optimization distribution strategy under the constraint conditions of actuator and the friction oval.Beyond that,when the optimal allocation algorithm is not applied,a method of axial load ratio distribution is adopted.Finally,Car Sim associated with Simulink simulation experiments are designed under the conditions of different velocities and different pavements.The simulation results show that the control strategy designed in this paper has a good following effect comparing with the reference model and the sideslip angle is controlled within a small rang at the same time.Beyond that,based on the optimal distribution mode,the electromagnetic torque phase of each wheel can follow the trend of the vertical force of the tire,which shows the effectiveness of the optimal distribution algorithm.

The Indirect Shared Steering Control Under Double Loop Structure of Driver and Automation

Due to the critical defects of techniques in fully autonomous vehicles,man-machine cooperative driving is still of great significance in today’s transportation system.Unlike the previous shared control structure,this paper introduces a double loop structure which is applied to indirect shared steering control between driver and automation.In contrast to the tandem indirect shared control,the parallel indirect shared control put the authority allocation system of steering angle into the framework to allocate the corresponding weighting coefficients reasonably and output the final desired steering angle according to the current deviation of vehicle and the accuracy of steering angles.Besides,the active disturbance rejection controller(ADRC)is also added in the frame in order to track the desired steering angle fleetly and accurately as well as restrain the internal and external disturbances effectively which including the steering friction torque,wind speed and ground interference etc.Eventually,we validated the advantages of double loop framework through three sets of double lane change and slalom experiments,respectively.Exactly as we expected,the simulation results show that the double loop structure can effectively reduce the lateral displacement error caused by the driver or the controller,significantly improve the tracking precision and keep great performance in trajectory tracking characteristics when driving errors occur in one of driver and controller.

Measurement of the peripheral aberrations of human eyes:A comprehensive review

It has been nearly 50 years since the first glimpse of the relationship between myopia and peripheral refractive errors. According to experiments on both animals and humans, the eyes with hyperopic peripheral vision appear to be at higher risk of developing myopia than those with myopic peripheral refractive errors. Despite the first measurement of peripheral refraction being achieved by a modified manual optometer, the concept of emmetropization triggered a rapidly increasing number of studies on peripheral aberrations. Not only the horizontal off-axis aberrations but also the meridional aberrations at different angles are measured by researchers during the development of peripheral aberrations measuring techniques. According to the differences among the working principles, a variety of techniques have been adopted for performing such measurements. The methods developed to realize the high-performance measurement involve the subject cooperating actively by rotating the head or eyes, the rotation of the whole optical path, and the combination of measurements of many light paths. This paper provides a review of the peripheral aberrations measuring techniques and their current status. This article also highlights the development trend of the measuring techniques of peripheral aberrations and practical applications of peripheral aberration measurements, such as the control of the accommodation, the measuring time, and the dynamic range problem of the wavefront sensor. Although wavefront sensing peripheral measurement is widely recognized for its capability to reveal both lower-order aberrations and higher-order aberrations, the efficiency of an autorefractometer is incomparable. The current study reveals that the most widely used peripheral aberration measurement methods are the use of an open field autorefractometer and Hartman-shack wavefront sensor-based techniques.

Litter decomposition and the degradation of recalcitrant components in Pinus massoniana plantations with various canopy densities

To understand the decomposition characteristics of Pinus massoniana foliar litter and the degradation of its refractory compounds in plantations under five canopy densities,a litter bag experiment over a decomposition time of 392 days was carried out.The results show that canopy density significantly affected decomposition rates of litter and degradation rate of lignin and cellulose.Litter decomposition rates decreased significantly with decreasing canopy density.Both lignin and cellulose degradation rates were lower with canopy densities of 0.62 and 0.74 as compared with the three other densities.Lignin and cellulose losses were more rapid in the first 118 days.Soil fauna had significant impacts on litter decomposition and the degradation of refractory compounds.Canopy density had significant effects on factors such as soil properties and soil fauna community structure,which could be conducive to the decomposition of litter and the degradation of litter recalcitrant components.Canopy density between 0.6 and 0.7 might be a favorable management practice promoting litter decomposition and beneficial for the sustainable development of P.massoniana plantations.

Integrated hydrologic modeling in the inland Heihe River Basin, Northwest China

As a typical inland river basin in arid Northwest China, having distinct hydrological characteristics and severe and repre- sentative water problems, the Heihe River Basin （HRB） has attracted considerable research interest worldwide and in 2007 became a pilot basin of the G-WADI network of UNESCO/1HR Many research programs have been conducted in the HRB since the 1980s, producing rich knowledge and data about the basin, which will be very helpful to further studies. This paper reviews research efforts related to hydrologic modeling and ongoing model integration studies performed in the HRB in re- cent years. Recently, an observation network covering the whole area and a Web-based data-sharing system have been estab- lished which can greatly improve data acquisition. This paper tabulates modeling activities in past years, including model ap- plications, model modifications and enhancements, and model coupling efforts. Also described is a preliminary modeling in- tegration tool designed to quickly build new models, which has been developed for hydrologic modeling purposes. Challeng- es and issues confronted in current studies are discussed, pointing toward key research directions in the future.

Wetland Purification Pattern for Surface Runoff Pollution of Coastal Highway in Liaoning Province

Taking surface runoff of Coastal Highway in Liaoning Province as research object,this paper analyzed water quality characteristics of runoff and flow rules of pollutants. It proposed using constructed wetland treatment technique in the drainage system from the perspective of effectively removing major pollutants. Using the constructed wetland k- C* model and relevant experience,parameters of constructed wetland can be obtained. The basic model is as follows: constructed wetland lies in two sides of the road,and surface runoff sewage is collected and treated separately with 1 km road section as the collection unit. The wetland area in one side is 191. 6 m2,average water depth is 0. 5 m,wetland width is 8 m,and wetland length is 24 m.

稀土配合物圆偏振发光性能研究进展

圆偏振发光不仅能直观地反映手性发光体系的激发态结构信息,而且在3D显示、手性识别、信息存储、光电器件及生物探针等领域具有广泛的应用.近年来,圆偏振发光材料引起了人们越来越多的关注,是当前发光材料领域新的研究热点.本综述从配合物和配体角度详细介绍了提高发光量子效率的结构设计策略,系统地总结了手性稀土发光配合物圆偏振发光性能的研究进展.本综述探讨了创新的结构设计策略,旨在开发性能卓越、结构稳定的手性稀土配合物,促进圆偏振发光材料领域的发展.