Automobile-Speed Estimation Using Movie-film Simulation

A silent movie film made by shooting through the windscreen of a car driven at different constant speeds was shown in an auditorium, and subjects asked to estimate the speed of the car. Of the 70 subjects who participated, 35 sat at the front and the remainder at the back.

The speed estimates of those seated at the back were, on average, some 11 per cent higher than those at the front. An explanation for this effect is given. It is shown that those at the correct perspective distance from the screen ( in the present case, those at the front) will receive an impression of speed which most closely resembles the actual speed of the car.

The speed estimates from the front of the auditorium most closely resembled those observed in an earlier field experiment when the subjects' hearing was diminished. It is concluded that the movie technique provides a good simulation of the task in the field experiment if the following two qualifications are made. First, the movie must be viewed from close to the correct perspective distance. Second, a silent movie corresponds to the real situation in which the observer is prevented from hearing.     

Motion extrapolation of auditory–visual targets

Many tasks involve the precise estimation of speed and position of moving objects, for instance to catch or avoid objects that cohabit in our environment. Many of these objects are characterised by signal representations in more than one modality, such as hearing and vision. The aim of this study was to investigate the extent to which the simultaneous presentation of auditory and visual signals enhances the estimation of motion speed and instantaneous position. Observers are asked to estimate the instant when a moving object arrives at a target spatial position by pressing a response button. This task requires observers to estimate the speed of the moving object and to calibrate the timing of their manual response such that it coincides with the true arrival time of the moving object. When both visual and auditory motion signals are available, the variability in estimating the arrival time of the moving object is significantly reduced compared to the variability in the unimodal conditions. This reduction in variability is consistent with optimal integration of the auditory and visual speed signals. The average bias in the estimated arrival times depends on the motion speed: for medium speeds (17 deg/s) observers’ subjective arrival times are earlier than the true arrival times; for high speeds (47 deg/s) observers exhibit a (much smaller) bias in the other direction. This speed-dependency suggests that the bias is due to an error in estimating the motion speeds rather than an error in calibrating the timing of the motor response. Finally, in this temporal localization task, the bias and variability show similar patterns for motion defined by vision, audition or both.     

动车组明线运行速度提高对空调工作的影响

为研究列车运行速度提高对空调工作的影响,采用三维定常不可压缩k-ε湍流模型,对不同运行速度下4辆编组的某新型动车组明线运行的空气动力学特性进行仿真,分析在不同运行速度下客室和司机室的空调冷凝器进、出口表面压力变化规律,预测冷凝风机通风量随列车运行速度提高的变化规律。计算结果表明:随着运行速度的提高,动车组车体表面和冷凝器进出口表面压力逐渐降低,冷凝器进、出口压差基本呈降低趋势,头车司机室和客室的前通风机通风量逐渐降低,尾车司机室和客室的后通风机压差为负且绝对值逐渐增大,说明通风机通风量逐渐提高。     

Minimum and comfortable driving headways: reality versus perception

A field study was conducted to evaluate drivers' actual headways in car-following situations, their relationship to the drivers' brake reaction times, and their relationship to the drivers' ability to estimate those headways using different metrics. Drivers were asked to maintain "minimum safe distance" and "comfortable, normal distance with no intention to pass" behind the car ahead. The lead car speeds varied from 50 to 100 km/hr. The results showed that under both sets of instructions, drivers adjusted their distance headways in relation to speed, maintaining constant time headways. A significant portion of the drivers maintained time headways that are considered unsafe in relation to drivers' reaction times. There was no significant relationship between the minimal headways maintained by the drivers and their brake reaction times under conditions of maximum attention and preparedness to apply brakes. Accuracy of spoken estimates of headways varied widely among the three measures used to report perceived headway; meters and car lengths yielded much lower estimates (and ones closer to the actual headways) than did seconds. The results have implications for headway perception, driving safety, driver education, and smart cruise-control design.     

基于物联网技术的长途客运车安全管理系统

物联网作为下一代信息网络的主体,是众多技术的融合体。本文设计了长途客运车安全管理系统模型,介绍了子系统的功能结构设计和子系统的主要功能,为解决长途客运车安全问题提供一种新的设想。该系统能有效地防止超载和超速,并且更好地监控驾驶员的状况和对客运车进行定位,使长途客运公司和交通管理部门更易于了解客运车的行车情况。     

The change in colour critical flicker fusion (CFF) values and accommodation times during experimental repetitive tasks with CRT display screens

Two groups of normal subjects were loaded an experimental visual task, or a calculating and discriminating task, on a CRT display screen under different work speeds and amounts. The colour (red, green and yellow) CFF values of the subjects were measured every 15 min during the task and their accommodative function, represented by the accommodation time, was measured before and after the task. The two groups of subjects showed no significant differences in the pattern of change in the colour CFF values. The green and yellow CFF deteriorated significantly at 30 min after the start of the task. The red CFF values decreased significantly at 15 min after the start of the task and this conditions continued to the end of the task. Both groups showed a lengthening accommodation relaxation time but no change in the accommodation relaxation time after the task. This increase in the relaxation time was larger in the group of subjects who were loaded a larger amount of work at a higher speed. The results suggest that the decrease in the CFF value of the subject, particularly when the subject sees light directly using a CRT display screen, does not signify the decline in the activity or consciousness level of the brain centre alone.     

一种基于单线圈速度估计的简单模型方法

实时准确的交通速度对于成功的快速路管理系统来说是至关重要的。然而,交通速度并不能直接从单线圈检测器测量出来。论文提出了一种基于单线圈输出量进行速度估计的简单模型方法。该方法考虑自由流和拥挤状态下分别采用不同的模型进行速度估计。利用该方法估计出来的速度非常接近于双线圈测量的速度观测值。与以往的算法相比,该方法简单实用并且明显地改善了速度估计。     

基于单线圈的速度估计混合模型

实时准确预测出交通速度对于成功的快速路管理系统来说足至关重要的。然而,交通速度并不能直接从单线圈检测器测量出来。该文提出了一种基于单线圈输出量进行速度估计的混合模型方法。该方法分别考虑自由流和拥挤两种不同状态下分别采用不同的模型进行交通速度的估计。模型系数的计算采用已知的单线圈输出量信息和交通流模型进行估计。整个算法采用matlab仿真软件仿真检验,结果表明利用该方法估计出来的速度非常接近于双线圈测量的速度观测值。与以往的算法相比,该方法简单实用并且明显地改善了速度估计。     

Estimation of Passenger Car Equivalents for single-lane roundabouts using a microsimulation-based procedure

Passenger car equivalents for heavy vehicles are required to carry out capacity calculations and perform operational analysis of any road entity (roadway segments or intersections). At single-lane roundabouts, the constraints to the vehicular trajectories imposed by the curvilinear geometric design and the driver's gap acceptance behaviour are expected to produce an impact of the heavy vehicles on the quality of traffic flow different from that produced on freeways and two-lane highways or other at-grade intersections. This is also because entering flow is opposed by the circulating flow which has priority and travels in an anticlockwise direction on a single-lane path around the central island.This paper addresses the question of how to estimate the passenger car equivalents for heavy vehicles on single-lane roundabouts. First, a comparison was performed between the empirical capacity functions based on a meta-analytic estimation of the critical and the follow up headways and the simulation outputs manually obtained for a single-lane roundabout built in Aimsun microscopic simulator. A genetic algorithm-based calibration procedure, therefore, was used to reach a better convergence between the simulation outputs and the empirical capacities. Based on the calibrated model, the passenger car equivalents were determined by comparing the capacity functions built for a fleet of passenger cars with the capacity functions calculated for different percentages of heavy vehicles. Differently from HCM 2010 which assumes a heavy vehicle to be equivalent to two passenger cars and sets as 2.0 the passenger car equivalents for heavy vehicles for roundabouts, a higher PCE effect would be expected on the quality of traffic conditions when the traffic stream contains a high number of heavy vehicles; this effect should be accounted for when calculating capacity and level-of-services.     

Intelligent Sound-Based Early Fault Detection System for Vehicles

An intelligent sound-based early fault detection system has been proposed for vehicles using machine learning. The system is designed to detect faults in vehicles at an early stage by analyzing the sound emitted by the car. Early detection and correction of defects can improve the efficiency and life of the engine and other mechanical parts. The system uses a microphone to capture the sound emitted by the vehicle and a machine-learning algorithm to analyze the sound and detect faults. A possible fault is determined in the vehicle based on this processed sound. Binary classification is done at the first stage to differentiate between faulty and healthy cars. We collected noisy and normal sound samples of the car engine under normal and different abnormal conditions from multiple workshops and verified the data from experts. We used the time domain, frequency domain, and time-frequency domain features to detect the normal and abnormal conditions of the vehicle correctly. We used abnormal car data to classify it into fifteen other classical vehicle problems. We experimented with various signal processing techniques and presented the comparison results. In the detection and further problem classification, random forest showed the highest results of 97% and 92% with time-frequency features.     

Objective evaluation of interior noise booming in a passenger car based on sound metrics and artificial neural networks

Booming sound is one of the important sounds in a passenger car. The aim of the paper is to develop the objective evaluation method of interior booming sound. The development method is based on the sound metrics and ANN (artificial neural network). The developed method is called the booming index. Previous work maintained that booming sound quality is related to loudness and sharpness - the sound metrics used in psychoacoustics - and that the booming index is developed by using the loudness and sharpness for a signal within whole frequency between 20 Hz and 20 kHz. In the present paper, the booming sound quality was found to be effectively related to the loudness at frequencies below 200 Hz; thus the booming index is updated by using the loudness of the signal filtered by the low pass filter at frequency under 200 Hz. The relationship between the booming index and sound metric is identified by an ANN. The updated booming index has been successfully applied to the objective evaluation of the booming sound quality of mass-produced passenger cars.     

The impact of hearing protection on sound localization and orienting behavior

The effect of hearing protection devices (HPDs) on sound localization was examined in the context of an auditory-cued visual search task. Participants were required to locate and identify a visual target in a field of 5, 20, or 50 visual distractors randomly distributed on the interior surface of a sphere. Four HPD conditions were examined: earplugs, earmuffs, both earplugs and earmuffs simultaneously (double hearing protection), and no hearing protection. In addition, there was a control condition in which no auditory cue was provided. A repeated measures analysis of variance revealed significant main effects of HPD for both search time and head motion data (p < .05), indicating that the degree to which localization is disrupted by HPDs varies with the type of device worn. When both earplugs and earmuffs are worn simultaneously, search times and head motion are more similar to those found when no auditory cue is provided than when either earplugs or earmuffs alone are worn, suggesting that sound localization cues are so severely disrupted by double hearing protection the listener can recover little or no information regarding the direction of sound source origin. Potential applications of this research include high-noise military, aerospace, and industrial settings in which HPDs are necessary but wearing double protection may compromise safety and/or performance.     

一种自适应在线核密度估计方法

给定一组观察数据,估计其潜在的概率密度函数是统计学中的一项基本任务,被称为密度估计问题.随着数据收集技术的发展,出现了大量的实时流式数据,其特点是数据量大,数据产生速度快,并且数据的潜在分布也可能随着时间而发生变化,对这类数据分布的估计也成为亟待解决的问题.然而,在传统的密度估计算法中,参数式算法因为有较强的模型假设导致其表达能力有限,非参数式算法虽然具有更好的表达能力,但其计算复杂度通常很高.因此,它们都无法很好地应用于这种流式数据的场景.通过分析基于竞争学习的学习过程,提出了一种在线密度估计算法来完成流式数据上的密度估计任务,并且分析了其与高斯混合模型之间的密切联系.最后,将所提算法与现有的密度估计算法进行对比实验.实验结果表明,与现有的在线密度估计算法相比,所提算法能够取得更好的估计结果,并且能够基本上达到当前最好的离线密度估计算法的估计性能.     

Passenger body vibration control in active quarter car model using ANFIS based super twisting sliding mode controller

This paper presents passenger body vibration control using an Adaptive Neuro Fuzzy Inference System (ANFIS) based super twisting sliding mode controller (ASTSMC) in active quarter car system. The proposed quarter car model is having three degrees of freedom composed of passenger body, sprung mass and unsprung mass. The random road profile is generated using ISO 8608 standard. The ride comfort of passenger body is calculated as per ISO 2631-1 standard. The simulation response is studied in time and frequency domain for passenger body acceleration and displacement in quarter car model. The response generated by ASTSMC controller for passenger body vibration suppression is compared with super twisting sliding mode controller and passive suspension system. The graphical and mathematical results proved the superiority of proposed ASTSMC controller in providing best ride comfort and safety to travelling passenger.     

Mental workload and cognitive task automaticity: an evaluation of subjective and time estimation metrics

Abstract

The evaluation of mental workload is becoming increasingly important in system design and analysis. The present study examined the structure and assessment of mental workload in performing decision and monitoring tasks by focusing on two mental workload measurements: subjective assessment and time estimation. The task required the assignment of a series of incoming customers to the shortest of three parallel service lines displayed on a computer monitor. The subject was either in charge of the customer assignment (manual mode) or was monitoring an automated system performing the same task (automatic mode). In both cases, the subjects were required to detect the non-optimal assignments that they or the computer had made. Time pressure was manipulated by the experimenter to create fast and slow conditions. The results revealed a multi-dimensional structure of mental workload and a multi-step process of subjective workload assessment. The results also indicated that subjective workload was more influenced by the subject's participatory mode than by the factor of task speed. The time estimation intervals produced while performing the decision and monitoring tasks had significantly greater length and larger variability than those produced while either performing no other tasks or performing a well practised customer assignment task. This result seemed to indicate that time estimation was sensitive to the presence of perceptual/cognitive demands, but not to response related activities to which behavioural automaticity has developed.     

Fuzzy Longitudinal Controller Design and Experimentation for Adaptive Cruise Control and Stop&;Go

This paper presents a fuzzy longitudinal control system with car-following speed ranging from 0 to 120 km/h, thereby achieving the main functions of both adaptive cruise control (ACC) and Stop&Go control. A fuzzy longitudinal controller is synthesized by inputting the difference of the actual relative distance and the safe distance obtained from the preceding vehicle, and the relative speed, and then outputting the pulse-width-modulation (PWM) signal to control the output forces of the vacuum boosters. With the use of the high-level controller from dSPACE, the fuzzy control law is easily and rapidly implemented using Matlab/Simulink for the experimental car, and the controller’s parameters can be changed and updated by analyzing data based on the relative distance using Lidar, the speed of the host vehicle, the opening of the throttle and the position of the braking pedal. For the sake of safe driving, experimental results are conducted by simulating the various possible car-following conditions for the ACC and Stop&Go controllers, thereby obtaining virtually relative distances and speeds to tune the controller’s parameters and ensure the safety of the controller. Several car following experiments are conducted to show that the proposed fuzzy longitudinal controller is capable of achieving the requirements of comfort and safety, and giving a satisfactory performance at high and low speed conditions.     

Simulation and analysis of the interior permanent magnet synchronous motor as a brushless AC-drive

In the present paper the behavior of the interior permanent magnet synchronous motor (IPMSM) fed by a current controlled voltage source inverter under static and dynamic conditions is presented. A method is explained, which estimates the rotor position angles and rotating speeds at several conditions by measuring the instantaneous values of stator voltages and currents. The estimator is an extended Kalman filter (EKF). The simulation results under four different dynamic conditions, namely the starting, loading of the motor, reversing of speed, and starting with unknown initial rotor position value, are presented.     

客车照明与信号灯多路传输控制系统的设计

本文以客车照明与信号灯的位置分布和安全性要求作为节点划分依据,采用控制器局域网CAN(ControllerAreaNet-work)构建了客车照明与信号灯多路传输控制系统,设计了系统结构、节点、相关流程图与硬件结构图,并采取指令控制——状态检测——状态指示的控制方式,实现车灯状态自动检测,增强客车行驶安全性。     

声速误差对平面波成像质量的影响

在医学超声成像系统中,大多都采用假定声速进行成像.假定声速和真实声速的误差会造成超声图像的空间相位偏移和散焦,降低图像质量.定量分析了声速误差对平面波成像质量的影响.通过Matlab里的k-wave仿真工具箱,获取仿真数据,假定不同声速,通过延迟累加波束形成技术来获得二维超声图像.通过对比度(Contrast Ratio,CR)、对比噪声比(Contrast-to-Noise Ratio,CNR)和点扩散函数(Point Spread Function,PSF)来评价平面波成像质量.在均一介质中,假定了21组不同的声速,其误差范围为±100 m/s;在复杂介质中,选择6种不同的乳腺模型,假定声速为1540 m/s,通过CR、CNR、PSF分别定量分析成像质量.在均一介质中,随着声速误差的增大,成像质量变差.在复杂介质中,成像质量比均一介质中使用正确声速的成像质量差.     

GUIDED PRACTICE IN DIRECT AND REVERSED SERIAL TRACKING

Abstract

A discrete tracking task was arranged in which movements of a lever extinguished a series of stimulus lights, using either compatible or incompatible display-control relationships. Movement of the lever could be controlled by the subject, or made automatic in order to provide guidance. Six groups of subjects were given nine, one or no guided runs before beginning normal practice on either the direct or reversed form of the task.

As expected, the reversed task was more difficult than the direct version. On both forms of the task guidance formed effective pretraining, although nine trials of guidance wore not nine times as effective as one such trial. Guidance tended to have a greater effect upon the reversed form of task, as would be expected were its main function to prevent the commission of errors.