基于行车安全场模型的交叉口车辆控制算法

为了提高网联环境无信号交叉口自动驾驶车辆的行车安全与通行效率问题,首先,建立无信号交叉口的行车安全场模型,构建包括车辆动力性能、制动性能以及通行交叉口所有车辆行车风险的目标函数,并设定相应的约束条件;然后,采用模型预测控制方法优化驶向交叉口车辆的行车策略;最后,基于VISSIM、MATLAB和NS3构建联合仿真试验平台,分别以车辆碰撞冲突类型、行车风险改善和道路拥堵程度验证并分析算法性能. 试验结果表明:在车流量和流量容积比大于1.0时,相比于传统的感应控制系统,本文提出的算法在延误时间、行程时间、冲突数目和通行能力的收益率分别大于90%、10%、10%和5%;在通信延迟低于100 ms,数据丢包在35%内,仍能够保证交叉口内车辆的通行效率.      

黔桂铁路双层集装箱运输必要性分析及改造方案

为提高西部陆海新通道的运输能力,综合考虑运输能力、陆海运输通道的协调性、节能降效等因素,结合陆海新通道双层集装箱运输不同径路在运行时长、运输能力等方面的对比,分析了黔桂铁路具备双层集装箱运输能力的必要性.针对黔桂铁路隧道地段建筑限界与接触网导高不满足双层集装箱运输要求的问题,通过方案比选,提出了合理的工程改造方案.为降...     

超软土地基浅层真空预压加固新技术现场试验及应用

对于新近吹填淤泥形成的超软土地基,常规浅层软基处理后表层形成的硬壳层承载力有限,还需吹填80~100 cm的粉砂作为满足后续机械插板施工的持力层。依托天津南港工业区港区航道、港池挖泥结合吹填造陆工程(B03路西侧造陆3区)软基处理工程,通过试验,对比分析3种浅层超软土加固处理新技术方案,并对3种方案进一步优化组合,在满足一定承载力的前提下,达到不吹填或少吹填粉砂的目的。     

欧Ⅳ标准催化转换器的结构设计

将催化转换器安装在发动机排气歧管出口位置,可以使催化剂快速起燃,充分发挥某些配方的催化剂效能,这被执行欧III和欧IV排放标准的车辆广泛应用。从催化转换器布置的角度,介绍这种催化转换器的结构设计,比较了布置方案,并对催化转换器中的零件如进气端管、壳体总成、出气端锥以及封装方案的设计要点作了描述。论述了该型催化转换器的气体流动特性、温度分布和塑性应变分布。     

深度学习在舰船前方障碍物图像识别中的应用

在舰船前方障碍物图像识别中,传统的图像识别系统漏检概率高、检测性能较差,难以满足舰船安全航行要求。深度学习是一种智能化技术,将其应用到障碍物图像识别中可以提高图像信息筛选、计算和检测效率。本文介绍深度学习中的神经网络模型和卷积神经网络,以及深度学习在舰船前方障碍物图像识别中的检测方法。基于传统深度学习算法的不足,提出改进后的Faster R-CNN方法在障碍物图像识别中的应用,并通过对比实验进行论证,实验结果表明改进后的图像识别模型具备检测精度高的应用优势。     

RADIOFREQUENCY ABLATION USING HYPERTONIC SALINE SOLUTION INSTILLATION: AN EX VIVO STUDY

Objective To determine whether radiofrequency ablation using hypertonic saline solution instillation can increase the extent of thermally mediated coagulation in ex vivo pig liver tissue. Methods Fifty-six radiofrequency ablation lesions were produced in fresh ex vivo pig's liver. According to different saline solutions, the lesions were divided into six groups: 25% acetic acid, 18% NaCl, 10% NaCl, 5% NaCl, 0.9% NaCl, and distilled water. After radiofrequency ablation, the lesions size and morphology were measured and compared.Results Using different instillation, the volume of coagulation necrosis was different: 25% acetic acid >18% NaCl >10% NaCl >5% NaCl >0.9% NaCl>distilled water. Conclusion Radiofrequency ablation using hypertonic saline solution instillation can increase the volume of radiofrequency ablation induced necrosis.     

EFFECT OF FUNDUS PIGMENT ON RESPONSE OF RABBIT RETINA TO TRANSPUPILLARY THERMOTHERAPY

Objective To study the effect of fundus pigment on the response of the retina to transpupillary thermotherapy (TTT). Methods The retina were irradiated with 810 nm diode laser in 16 eyes of 8 pigmented rabbits and 12 eyes of 6 albino rabbits. The spot size was 1.2 mm; the duration was 60 s; and powers were 50, 80, 150 and 300 mW for pigmented rabbits and 800, 1 200 and 1 500mW for albino rabbits. All of the eyes were followed up with ophthalmolscope. The fundus was photographed and examined histologically with optic microscope immediately and 1 month after TTT respectively. Results The changes of the fundus and the histological examination were not significant immediately and 1 month after TTT in 50 mW group of pigmented rabbit and 800 mW of albino rabbit. Grey spot on the retina was observed on the fundus in 80 mW group of pigmented rabbit and 1 200 mW of albino rabbit immediately after TTT. The structure of the retina remained intact and subretinal fluid was observed histologically. Grey spot was still visible on the fundus, though the fluid was absorbed after 1 month. As the power of diode laser was increased to 150 mW for pigmented rabbits and 1500 mW for albino rabbit, fundus white spots were observed and the outer retina was destroyed while photoreceptors existed immediately after TTT. Pigmentation was found in white lesions and the fibrous proliferation was found in choroid 1 month after TTT. Prominent white spot was seen on the fundus immediately after laser irradiation of 300 mW in pigmented rabbits and the structure of the retina was obscured. One month after TTT, dense pigmentation appeared at laser lesions. The retina was thinner. There was prominent fibrous proliferation in the choroid. Conclusion The fundus pigment seems to play an important role in the response of the retina to TTT. The reaction of the retina is in proportion to the intensity of laser.     

城市轨道交通列车车外噪声特性

基于统计能量分析(SEA)和半无限流体方法,建立6节编组的B型列车车外噪声预测仿真模型;通过试验提取车体SEA模型的振动激励和轮轨噪声激励,施加给车体并计算分析了车外噪声特性;以中国某城市轨道交通列车通过噪声试验对模型进行验证,并探讨了列车各板单元和轮轨噪声声源对车外场点声压的贡献量.研究结果表明:统计能量分析和半无限...     

基于改进模糊算子和形态学的舌体分割方法

舌诊是中医望诊中的重要内容,为了自动分析舌体的各项指标,必须将舌体从背景区域中分割出来.由于舌体与脸部等背景区域颜色较为接近,提出一种基于改进模糊算子和形态学的舌体分割方法,该方法根据由大津法确定的阈值定义隶属函数,取得了令人满意的分割效果.     

行人主动安全系统对交通流运行状态影响分析

行人主动安全系统能够有效降低人车碰撞风险,但其对交通流长时间运行状态的影响有待探究.运用Net Logo软件,基于智能体建模思想设置车辆和行人运动模式,选择平均车速波动情况和车辆等待时间、行人等待时间、行人速度分布评估传统车辆、行人检测系统车辆和人车通讯系统研究车辆运行时的交通流稳定性和通行效率.研究结果表明:行人主动...