New Method for Confirming the Desired Safety Headway Distance and Desired Deceleration in ACC System

A new method of confirming the desired safety headway distance and desired deceleration is put forward according to the detected static or moving target and its simulation results in Matlab are also presented. The validity of the algorithm to calculate the reference speeds of both the ACC vehicle and the targeted car according to the vector quadrangle composed of the relative distance, the relative azimuth angle, the relative speeds of the vehicles has also been demonstrated through numerical example in Matlab. New laws to obtain the desired deceleration by estimating the braking force according to the vehicle analyses force equation are established too.

MMII程序模式在New Headway English Course语法教学中的应用

在英语教学中,语法占据着重要的位置,但我国的语法教学却越来越注重语言形式,脱离了语言的意义和交际。MMII程序模式是在认知法、学习层级理论以及MMC操练模式的基础上形成的,包括机械操练、有意义操练、互动活动和整体任务四个程序,突出了在真实情境中对学生语言运用能力的培养。该程序对于教师的语法教学有一定的启示。

Capacity of unsignalized intersection with mixed distribution headway

In order to describe the time-headway distribution more precisely in urban traffic network,the mixed distribution model was introduced which has been widely used in mathematical statistics,and a capacity model of unsignalized intersections was obtained based on gap acceptance theory.The new model is suitable for absolute and limited priority controlled conditions and can be regarded as a more general form which handles simple headway distributions including lognormal distribution,negative exponential distribution and shifted negative exponential distribution.Through analyses of the main influencing factors in this model,the proportion of free flowing and the standard variance of gaps between any two continuous following vehicles are high sensitivity with the capacity when major stream volume is low.Besides,the capacity is affected deeply by the mean value of following vehicle gaps when major stream value is fixed and the proportion of free flowing is small.At last,the observed minor stream capacity is obtained by the survey date in Changchun city,and the average relative error between the theoretical capacity proposed in this paper is 13.73%,meanwhile the accuracy increases by 16.68% compared with the theoretical value when major stream obeys shifted negative exponential distribution.

A Look at The Syllabus of New Headway Intermediate Students' book and Its Implementation on Chinese Middle School Students

The purpose of this assignment is to evaluate the course book New Headway intermediate students’book.The teaching context of using this book will be described clearly before discussing the syllabus terms and types which are related to the course book.In addition,the selection and ordering of elements in this course book will be analyzed,the problems and solutions of using this book in teaching context will also be discussed.

New Headway in China's Offshore Oil Cooperation with Foreign Firms

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Study on the pattern of train arrival headway time in high-speed railway

Purpose-The design goal for the tracking interval of high-speed railway trains in China is 3 min,but it is difficult to achieve,and it is widely believed that it is mainly limited by the tracking interval of train arrivals.If the train arrival tracking interval can be compressed,it will be beneficial for China's high-speed railway to achieve a 3-min train tracking interval.The goal of this article is to study how to compress the train arrival tracking interval.Design/methodologylapproach-By simulating the process of dense train groups arriving at the station and stopping,the headway between train arrivals at the station was calculated,and the pattern of train arrival headway was obtained,changing the traditional understanding that the train arrival headway is considered the main factor limiting the headway of trains.Findings-When the running speed of trains is high,the headway between trains is short,the length of the station approach throat area is considerable and frequent train arrivals at the station,the arrival headway for the first group or several groups of trains will exceed the headway,but the subsequent sets of trains will havea headway equal to the arrival headway.This convergence characteristic is obtained by appropriately increasing the running time.Originality/value-According to this pattern,there is no need to overly emphasize the impact of train arrival headway on the headway.This plays an important role in compressing train headway and improving high-speedrailwaycapacity.

Communication Resource-Efficient Vehicle Platooning Control With Various Spacing Policies

Platooning represents one of the key features that connected automated vehicles may possess as it allows multiple automated vehicles to be maneuvered cooperatively with small headways on roads. However, a critical challenge in accomplishing automated vehicle platoons is to deal with the effects of intermittent and sporadic vehicle-to-vehicle data transmissions caused by limited wireless communication resources. This paper addresses the co-design problem of dynamic event-triggered communication scheduling and cooperative adaptive cruise control for a convoy of automated vehicles with diverse spacing policies. The central aim is to achieve automated vehicle platooning under various gap references with desired platoon stability and spacing performance requirements, while simultaneously improving communication efficiency. Toward this aim, a dynamic event-triggered scheduling mechanism is developed such that the intervehicle data transmissions are scheduled dynamically and efficiently over time. Then, a tractable co-design criterion on the existence of both the admissible event-driven cooperative adaptive cruise control law and the desired scheduling mechanism is derived. Finally, comparative simulation results are presented to substantiate the effectiveness and merits of the obtained results.

Headway duo微导管联合Onyx胶在脑膜瘤切除术前栓塞治疗中的应用分析

目的评价Headway duo微导管联合Onyx胶在脑膜瘤切除术前栓塞治疗中的应用价值。方法深圳市人民医院神经外科自2015年12月至2017年3月在脑膜瘤切除术前应用Headway duo微导管联合Onyx胶栓塞脑膜瘤12例，按Manelfe脑膜瘤供血方式分型显示Ⅰ型5例，Ⅱ型3例，Ⅲ型2例，Ⅳ型2例。回顾性分析患者的临床资料，通过比较栓塞前后的数字减影血管造影（DSA）肿瘤染色结果评估肿瘤的栓塞程度并记录栓塞相关并发症。结果栓塞术后DSA显示：肿瘤少部分栓塞者0例，部分栓塞者2例，大部分栓塞者5例，肿瘤完全栓塞者5例。仅2例患者在栓塞过程中出现头面部疼痛感觉，操作停止后即消失；本组脑膜瘤切除术中平均出血量为685mL，平均手术时间为4．45h。结论脑膜瘤切除术前应用Headway duo微导管联合Onyx胶栓塞治疗安全、有效，可以起到良好的血流阻断作用，值得临床推广。

Will Crash Experience Affect Driver’s Behavior? An Observation and Analysis on Time Headway Variation Before and After a Traffic Crash

Research into the impact of road accidents on drivers is essential to effective post-crash interventions.However,due to limited data and resources,the current research focus is mainly on those who have suffered severe injuries.In this paper,we propose a novel approach to examining the impact that being involved in a crash has on drivers by using traffic surveillance data.In traffic video surveillance systems,the locations of vehicles at different moments in time are captured and their headway,which is an important indicator of driving behavior,can be calculated from this information.It was found that there was a sudden increase in headway when drivers return to the road after being involved in a crash,but that the headway returned to its pre-crash level over time.We further analyzed the duration of the decay using a Cox proportional hazards regression model,which revealed many significant factors(related to the driver,vehicle,and nature of the accident)behind the survival time of the increased headway.Our approach is able to reveal the crash impact on drivers in a convenient and economical way.It can enhance the understanding of the impact of a crash on drivers,and help to devise more effective re-education programs and other interventions to encourage drivers who are involved in crashes to drive more safely in the future.

Comparison of Vehicle Departure Headways in Beijing and Atlanta

Two characteristics of traffic flows make the vehicle departure headways in Beijing, China different from that in Atlanta, USA. Urban traffic flows in China are often hindered by pedestrians at intersections and queuing vehicles often cannot be totally discharged during the green time, so most signalized intersections are over-saturated in the day time. The first characteristic makes the departure headways of the first and second vehicles in Beijing depend heavily on the start-up situations （with or without interference）. The departure headways of the 3rd to 5th vehicles in Beijing have similar characteristics to those in Atlanta. The second characteristic makes the departure headways after the 5th vehicle significantly different from those in Atlanta. These comparisons show that the conventional delay estimate methods and signal control algorithms may not fit Chinese scenarios, which makes imported intelligent traffic control systems not work well in China without calibrations.

Headway on the Maritime Silk Road

Headway on the Maritime Silk Road is a book generously illustrated with photos from the documentary film of same name on CCTV.It tells the stories of more than 30 figures from around a dozen countries along the Maritime SiLk Road.Inheriting the piioneering spirit of their enterprising ancestors,these figures have received family businesses or passed them on.

Feedback control scheme of traffic jams based on the coupled map car-following model

Based on the pioneering work of Konishi et al. [Phys. Rev. E （1999） 60 4000], a new feedback control scheme is presented to suppress traffic jams based on the coupled map car-following model under the open boundary condition. The effect of the safe headway on the traffic system is considered. According to the control theory, the condition under which traffic jams can be suppressed is analyzed. The results are compared with the previous results concerning congestion control. The simulations show that the suppression performance of our scheme on traffic jams is better than those of the previous schemes, although all the schemes can suppress traffic jams. The simulation results are consistent with theoretical analyses.

Interval Type-2 Fuzzy Hierarchical Adaptive Cruise Following-Control for Intelligent Vehicles

Intelligent vehicles can effectively improve traffic congestion and road traffic safety.Adaptive cruise followingcontrol(ACFC)is a vital part of intelligent vehicles.In this paper,a new hierarchical vehicle-following control strategy is presented by synthesizing the variable time headway model,type-2 fuzzy control,feedforward+fuzzy proportion integration(PI)feedback(F+FPIF)control,and inverse longitudinal dynamics model of vehicles.Firstly,a traditional variable time headway model is improved considering the acceleration of the lead car.Secondly,an interval type-2 fuzzy logic controller(IT2 FLC)is designed for the upper structure of the ACFC system to simulate the driver's operating habits.To reduce the nonlinear influence and improve the tracking accuracy for the desired acceleration,the control strategy of F+FPIF is given for the lower control structure.Thirdly,the lower control method proposed in this paper is compared with the fuzzy PI control and the traditional method(no lower controller for tracking desired acceleration)separately.Meanwhile,the proportion integration differentiation(PID),linear quadratic regulator(LQR),subsection function control(SFC)and type-1 fuzzy logic control(T1 FLC)are respectively compared with the IT2 FLC in control performance under different scenes.Finally,the simulation results show the effectiveness of IT2 FLC for the upper structure and F+FPIF control for the lower structure.

Estimation of Passenger Car Equivalents for Basic Freeway Sections at Different Traffic Conditions

Passenger car equivalent (PCE) is an important factor which is used to convert traffic volumes containing proportions of heavy good vehicles (HGVs) to a unify measure containing only passenger cars units (PCU). This paper uses large data base of real traffic raw data extracted from loop detector before being aggregated to estimate PCEs. These detectors are located on the M25 and the M42 motorway sites in the United Kingdom. The selected sites represent basic freeway segments as they are far away from the influence of entrance (on ramp) and exit (off ramp) sections. The data are filtered properly so as to estimate passenger car equivalents (PCEs) using lagging headway method for close following situations at different speed ranges. The results suggest that for the same location, the equivalency factors are varies significantly based traffic speed. However, it is proved that such variation with traffic speed is influenced by the differences in lengths between HGVs and cars. Regression models have also been developed linking the PCEs with traffic speed.

Smartphones and traffic signals:A quantitative assessment for phone usage behavior on performance of signalized intersections

Modern smartphones differ vastly from classic cellphones with enormous capabilities,changing cellphones from making phone calls and short messages to pocket-sized computers with full internet connectivity.The downside of modern phone evolution is changing drivers’behavior and phone usage addiction.Several researchers have investigated the safety implications of phone usage while driving on accidents risk.Nevertheless,the effect of phone usage on the performance of traffic facilities did not receive equal attention.Hence,this research aims to study the impact of smartphone usage on traffic signal operations.The parameters considered in the study were drivers’activity while waiting at the signal,startup lost time,and saturation flow rate.The study team covered 25 intersections in the study area,observed the activities of over 6800 drivers while waiting at the signal,and recorded their corresponding discharge headways.The study team then supplemented field data with a behavioral survey questionnaire for drivers living in the study area to interpret field observations.Finally,the collected data were processed and analyzed,resulting in mathematical models for the relationship between the reduction in saturation flow rate and the red time interval.The team found two primary conclusions.The study’s first finding was that the traditional concept for estimating startup lost time adopted by the highway capacity manual(HCM)appears inaccurate.The field results revealed that the lost times caused by other distracted drivers upstream in the queue were comparable to the estimated startup lost time following the HCM method for estimating startup lost time.The second finding was that the reduction in saturation flow rate at the traffic signal is an exponential function of the red time interval,reducing the overall capacity for the intersection and increasing the average delay.Finally,the authors suggest mitigating the problem and making recommendations for future research.

Research on head way control of a guided transport system based on intersection condition evaluation

ln order to ensure the safety and efficiency of the section tracking operation of a guided transport system,a safety headway control method of section tracking based on intersection conditions is proposed in this paper.Considering the difference of signal phase,the evaluation model of road conditions was established based on a fuzzy comprehensive evaluation method,FAGT.Based on the artificial potential field method,the time-varying hybrid artificial potential field(TH-APF)method was proposed,and the tracking headway control algorithm was designed to realize the dynamic control of the tracking headway of the guide transport vehicle.The simulation results verified the effectiveness and applicability of the evaluation model of intersection road conditions;the tracking headway can be maintained at about 120 s.The tracking headway control algorithm of guided transport vehicles can respond to the road conditions and avoid the local optimum of the artificial potential field method,thus improving the operating efficiency.

Capacity of Multi- vehicle- types Mixed Traffic Flow

：Based on the gap acceptance theory, the mixed traffic flow composed of r representative typesflows on the unsignalized intersection is set up. It is an extension of capacity model for one type vehicletraffic flow, and it is very fitter to the Chinese highway traffic condition than the other models.

Dangerous Driving Behavior Recognition and Prevention Using an Autoregressive Time-Series Model

Time headway is an important index used in characterizing dangerous driving behaviors. This research focuses on the decreasing tendency of time headway and investigates its association with crash occurrence. An autoregressive（AR） time-series model is improved and adopted to describe the dynamic variations of average daily time headway. Based on the model, a simple approach for dangerous driving behavior recognition is proposed with the aim of significantly decreasing headway. The effectivity of the proposed approach is validated by means of empirical data collected from a medium-sized city in northern China. Finally, a practical early-warning strategy focused on both the remaining life and low headway is proposed to remind drivers to pay attention to their driving behaviors and the possible occurrence of crash-related risks.

nvestigating the role of exiting vehicles and turn indicator usage in gap acceptance at single-lane roundabouts

Roundabouts are becoming a preferred form of intersection control type due to their safety and capacity benefits. Yield control at roundabout entries inherently reduces fuel consumption and emissions when compared to other conventional intersection types. However, these benefits can be limited by poor driver behavior and judgment when entering the roundabout. This research addresses the nature of gap distributions and use of turn indicators by exiting vehicles at three single-lane roundabouts in Vermont, New York, and Alaska. Presented here is a comparison of vehicle headways measured at two different locations in each roundabout. Rejected headways are analyzed in the context of priority abstaining events when entering drivers yield to vehicles exiting on the same leg of the roundabout suggesting that ＂true＂ critical gaps are being overestimated. Results indicate that exiting vehicles, particularly those that do not use their turn indicators when departing from the major-stream of traffic have an influence on the entry decision of drivers on the same approach. This behavior is of particular concern for intersection efficiency （i.e., delay） and sustainability （i.e., excess fuel consumption and emissions）. Results prompt the consideration of more consistent guidance on and enforcement of turn indicator use during roundabout negotiations.