Vehicle Ego-Localization Based on Streetscape Image Database Under Blind Area of Global Positioning System

Vehicle positioning is critical for inter-vehicle communication, navigation, vehicle monitoring and tracking. They are regarded as the core technology ensuring safety in everyday-driving. This paper proposes an enhanced vehicle ego-localization method based on streetscape image database. It is most useful in the global positioning system(GPS) blind area. Firstly, a database is built by collecting streetscape images, extracting dominant color feature and detecting speeded up robust feature(SURF) points. Secondly, an image that the vehicle shoots at one point is analyzed to find a matching image in the database by dynamic programming(DP)matching. According to the image similarity, several images with higher probabilities are selected to realize coarse positioning. Finally, different weights are set to the coordinates of the shooting location with the maximum similarity and its 8 neighborhoods according to the number of matching points, and then interpolating calculation is applied to complete accurate positioning. Experimental results show that the accuracy of this study is less than 1.5 m and its running time is about 3.6 s. These are basically in line with the practical need. The described system has an advantage of low cost, high reliability and strong resistance to signal interference, so it has a better practical value as compared with visual odometry(VO) and radio frequency identification(RFID) based approach for vehicle positioning in the case of GPS not working.

METALLOGENIC REGULARITIES OF LARGE CONCEALED AND BLIND URANIUM DEPOSITS AND METALLOGENIC PROGNOSIS BY SYNTHETIC INFORMATION IN GRANITIC EXOCONTACT ZONES──Taking Eastern Hunan and Adjacent Areas as Examples

Under the guide of advanced theories of geosciences, new technology and methods of prospecting, integrating sedimentation, magmatic emplacement, metamorphism and deformation with mineralization by means of intersectional subjects, the author has revealed that the geodynamic setting of formation of uranium deposits of granitic exocontact zone type in eastern Hunan and neighbouring areas has a specia1 stretching strike-slip structure, a special thermal rock series,a special texture and composition of the crust and mantle, elaborated the macroscopic and microscopic features of stretching decollement faults in the Mingyuefeng area, and summed up the metallogenic regularities of typical uranium deposits, factors for a genetic mode1 and the criteria for prospecting by synthetic information, on the basis of which he has made prognosis of concealed and blind uranium deposits.

Reconstruction of hollow areas in density profiles from frequency swept reflectometry

The standard density profile reconstruction techniques are based on the WKB approximation of the probing wave’s phase,making them unable to properly reconstruct blind areas in the cut-off frequency profile.The reconstruction suffers a significant immediate error that is not rapidly damped.It is demonstrated that even though no reflections occur inside the hollow region causing the blind area,the higher probing frequencies that propagate through it carry information that can be used to estimate its properties.The usually ignored full-wave effects were investigated with the use of full-wave simulations in 1 D,with special attention paid to the frequency band where they are dominant.A database of perturbation signals was simulated onfive-dimensions of parameters and an application of the database inversion was demonstrated for a magnetic island in a Tore Supra discharge.The new adapted reconstruction scheme improved the description of the density profile inside the hollow region and also along 10 cm after it.

低频脉冲磁场慢性暴露对健康成年股四头肌收缩力及形态的影响

背景:目前已有关于低频脉冲磁场对骨骼肌结构形态影响研究发现了骨骼肌质量变化,但对接受慢性暴露后的形态变化未见相关研究。目的:观察低频脉冲磁场慢性暴露对腿部股四头肌最大自主收缩力与形态指标的影响,为使用该技术作为肌肉功能改善策略提供组织形态变化的参考依据。方法:招募普通健康受试者70名,随机分为接受磁场刺激的试验组与进行假治疗的对照组,每组35名,试验时长共计4周,试验组受试者每隔48 h进行1次15 min的低频脉冲磁刺激干预,对照组进行假治疗,干预间隔与时长与试验组一致,干预4周后观察不同组别受试者股四头肌最大自主收缩力值变化,利用B型超声影像作为评估手段,观察肌肉厚度、肌肉横截面积及羽状角指标的变化。结果与结论:①经过4周的低频脉冲磁场慢性暴露,68名受试者完成试验,试验组受试者股四头肌最大自主收缩力测试值显著增长(P=0.000),提升幅度显著高于对照组(P=0.008);②试验组受试者的肌肉形态3项指标均显著高于试验前测(P=0.000),而对照组肌肉厚度指标呈显著性下降(P=0.020),羽状角无显著性变化,横截面积显著性提升(P=0.000);③组间对比发现,试验组关于肌肉形态的肌肉厚度(P=0.012)、羽状角(P=0.003)及横截面积(P=0.049)3项指标均显著高于对照组;④上述数据证实,健康成年受试者经过4周的低频脉冲磁场慢性暴露,股四头肌的最大自主收缩力显著提升,同时观察到试验组的肌肉厚度、横截面积及羽状角3项肌肉形态指标的显著增长,对使用该技术作为肌肉改善的运动替代与医疗策略提供了肌组织形态改善的支持依据。

Research of the Exploitation of Human Resources in Blind Prevention and Primary Eye Care

Purpose:This research studied how to establish a relatively advanced blindness prevention and eye care cause in economically underdeveloped countryside.Methods:Ophthalmic vocational schools and professional lectures were held to train“practical type”primary eye care workers for the coumtryside.Further study in high-level(above provincial)hospitals was taken to train blindness preention &eye care backbones and leaders.Results:In 1986,the ratio of the number of the eye care workers of all levels to the number of the whole population in the prefecture was1:26000.In1992,it roseto1:17000.Aneye care network of 222stations had been established in tb countryside.Ten in the 13county hospitals had a seperated ophthalmology ed- partment,in which 3were awarded“National advanced blindness prevention County”.Twenty one hospitals were appointed as the Unit of Surgical Vision-Rehabilitation of Cataract.Blindness prevention and eye care convered1000000population(eye care avaliable within 5kilometers),23.5%of the whol popula-tion.Conclusions:In a demographically large but economically underdexeloped country-side area,the key to wide-range blindness prevention and eye oare is to exploti human resources effectively.We should train“Practical type”primary eye care workers,and have a number of edpartment leaders who are authoritive,influential in this field and ready to sacrifice to this cause.

Discussion on the application prospect of the transient electromagnetic method based on the dual launcher and mine advanced detection

The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is rarely reported in the detection of pipelines in urban geophysical exploration and the application of coal mines. Based on this, this paper realizes the equivalent anti-magnetic flux transient electromagnetic method based on the dual launcher. The suppression effect of this method on the blind area is analyzed by physical simulation. And the detection experiment of underground pipelines is carried out outdoors. The results show that the dual launcher can significantly reduce the turn-off time, thereby effectively reducing the impact of the blind area on the detection results, and the pipeline detection results verify the device’s effectiveness. Finally, based on the ground experimental results, the application prospect of mine advanced detection is discussed. Compared with other detection fields, the formation of blind areas is mainly caused by the equipment. If the dual launcher can be used to reduce the blind area, the accuracy of advanced detection can be improved more effectively. The above research results are of great significance for improving the detection accuracy of the underground transient electromagnetic method.

交替极化阵列对消盲区分析与验证

当干扰信号的空域和极化域特征与目标信号相似时,采用空极化域联合抗干扰技术在消除干扰的同时也会抑制目标信号,导致干扰对消后信干噪比(signal to interference plus noise ratio,SINR)低于雷达系统需求,从而形成干扰对消盲区。针对这一现象,通过在空域、极化域与空极化域分别建立交替极化阵列对消盲区模型,推导了对消盲区位置和大小的数学表达式,从而给出了交替极化阵列对消盲区的数学表征方法。进而分析了交替极化阵列对消盲区的分布规律与影响因素,研究发现阵元间距能够显著影响交替极化阵列对消盲区的分布,在相同条件下交替极化阵列对消盲区大于共点极化阵列对消盲区,结果表明交替极化阵列虽然通过减少天线数目降低了设备成本,但增大了阵列的对消盲区。然后,对消盲区模型进行了数值仿真,仿真结果验证了理论分析。最后,利用信道模拟器搭建了实验平台,信道模拟实验测得的对消盲区与理论值基本一致,再次证明了分析结论的有效性。

动态膜厚的超声实时测量方法及测量盲区影响因素

基于超声波技术的弹簧模型与共振模型之间存在一段膜厚测量盲区,本文中提出了1种复合模型可覆盖测量盲区.为实现膜厚在线监测,自主搭建了动态膜厚的超声实时测量系统,并研究了配副类型和润滑剂种类对测量盲区的影响.构建了超声测量试验的理论模型,对超声波在介质内的传播规律进行了仿真分析.结果表明,自主搭建的膜厚实时测量系统可精密跟踪不同周期及不同波形的膜厚;提出的复合模型可实现单个探头对宽范围膜厚的全域测量;随着下摩擦副声阻抗和润滑剂声阻抗的增大,膜厚测量盲区逐步缩小;但当润滑剂声阻抗过小时,容易出现无法监测的“测量真空区”.本文工作可为金属摩擦副在实际工况下的动态膜厚在线监测提供理论和技术参考.

智能汽车变道盲区影像对驾驶员认知负荷与安全性的影响

智能汽车变道盲区影像在为驾驶员提供更多环境信息的同时也可能增加驾驶员的认知负荷。针对这一问题,提出改进AttenD算法,建立认知负荷与驾驶员注视点分布的关系模型,对3种智能汽车品牌车辆开展实车路测实验,分析多种外部条件下驾驶员与不同变道盲区影像交互过程中注视特征、驾驶行为特征以及认知负荷的差异。结果表明,增大盲区影像面积、提高盲区影像面积占中控屏面积的比例、减少扫视路径冗余能降低变道过程中的认知负荷。

自卸车右转盲区风险目标动态检测算法研究

针对自卸车外形尺寸大导致车辆右转弯时存在较大视野盲区的问题,提出一种自卸车右转盲区风险目标动态检测算法,该算法利用YOLOv8模型的C2f模块和损失计算模块,提高了模型的检测精确率。同时,在盲区中预设4条位置阈值线,增加盲区风险预警模块,建立了自卸车右转盲区辅助驾驶系统。结果表明:所提出的风险目标动态检测算法能够识别小型乘用车、载货汽车、公交车、行人和电动自行车等多种类型的目标,且所有类别目标的50%交并比阈值下的平均精度均值(mAP50)为0.87;自卸车右转盲区辅助驾驶系统能够根据图像中风险目标框的位置进行不同程度的预警。

基于四开关升降压变换器的三模式设计

四开关升降压(four-switch buck-boost,FSBB)变换器具有宽范围电压输入的优势。由于开关频率高,变换器工作在降压(Buck)模式或者升压(Boost)模式下效率最高,但是在输入电压改变时,两种模式之间的切换会产生转换盲区。文中采用脉宽调制(pulse width modulation,PWM)技术,对传统的两模式控制方法加以改进,设计加入了第三种升降压(Buck-Boost)模式进行平滑过渡。实验结果表明,瞬时改变输入电压时,输出电压波形波动小,证明新的控制方法有效地解决了转换盲区问题,保证了输出电压的稳定。

大型局域网安全盲区探析

提出了大型局域网安全相关的网络盲区、资产盲区和安全盲区,分析了3个盲区产生的原因,阐述了3个盲区的形态,指出了3个盲区对大型局域网安全的影响,为解决大型局域网的安全问题提供了新的角度.

机车乘务员辅助瞭望及障碍物智能预警系统研究

近年来随着铁路运输任务的加重,对机车运行的可靠性、安全性也提出更高的要求。因机车设计原因造成司机瞭望视角存在较大盲区,同时机车运行路线存在非封闭区间路口等,机车乘务员远距离瞭望存在困难。该文以解决机车瞭望盲区问题、机车乘务员远距离瞭望问题为目标,利用探测雷达技术与视频影像分析系统相结合的方式,对机车瞭望盲区内的人员、车辆、障碍物进行探测感知,同时将告警信息向机车乘务员提示,达到提示机车乘务员安全驾驶,最大限度地降低安全事故发生的目的。

起伏薄煤层顺层孔工艺研究

我国南方地区的煤层赋存条件复杂,煤层较薄,倾角变化大,常规钻进工艺无法有效完成工作面顺层孔施工要求,存在抽采空白带。为了消除肥田矿111601工作面抽采盲区,在111601工作面进行顺层孔施工工艺试验研究。试验采用扶正器保直钻具组合和定向钻进2种施工工艺,根据钻孔轨迹分析了偏移规律及煤层赋存条件。现场试验表明,单一的保直钻具组合无法满足消除抽采盲区的目的;定向钻进工艺能通过分支孔施工,适应煤层起伏,使钻孔从一侧覆盖整个工作面宽度,有效消除了工作面中部抽采盲区,对于后续该工作面抽放钻孔施工具有指导作用。

基于PC-Crash的大型车辆转弯盲区预警控制模型仿真研究

大型车辆在转弯的时候,前后车轮的运动轨迹并不一致,形成内轮差,车子的后半部分车轮对弯道内侧的行人及车辆产生巨大的威胁。针对大型车辆转弯盲区智能预警系统的控制模型开展仿真研究。首先PC-Crash仿真软件构建车辆模型,选取车辆轴距和转弯半径参数进行转弯行驶内轮差影响规律仿真分析,当转弯半径和轴距对内轮差影响的变化规律如下:随着转弯半径的增大,半挂汽车转弯的内轮差逐渐减小;随着轴距的增加,半挂汽车转弯的内轮差逐渐增大的变化规律。然后利用PreScan仿真试验确定车辆不同转弯角度的转弯盲区以及相应的车载雷达探测角度,并建立转弯角度-内轮差-雷达探测角度模型方程,用于大型车辆转弯盲区智能预警方案设计,以降低或消除汽车在转弯行驶时行车安全风险。

复合地层矩形顶管开挖盲区处理技术探索研究

为解决组合式旋转刀盘矩形顶管掘进机在复合地层中顶推施工的局限性,依据顶管掘进范围内岩体物理力学性质、横断面及纵轴向分布范围、埋深、地下水赋存情况及地面环境条件等的不同,提出从设备优化设计和盲区预处理两个方面来解决复合地层矩形顶管盲区处理问题。在设备优化设计方面,针对矩形顶管掘进机设计与制造环节,提出从优化刀盘布置和盲区位置增设辅助切削系统两种方法来增强其在复合地层中的适应性;在盲区预处理方面,针对预处理技术,提出3种水平处理方法及地面处理方法。为矩形顶管掘进机复合地层掘进施工提供了新的解决方案。

基于前视摄像头和角雷达的盲区报警制动系统研究

为了探索以更智能、更方便为目的的盲区监测提醒制动系统,结合前视摄像头和超声波配合仪表显示系统进行盲区行人和车辆报警及提醒。探索一种基于前视摄像头,在超声波和环视的基础上增加角雷达盲区报警制动系统的研究,且该方案可作为后续车型功能开发设计参考方案。该方案硬件可以共用,只需改动软件部分即可实现。结果显示,基于前视摄像头和角雷达的盲区报警制动系统可以及时报警或制动,提醒驾驶员注意盲区目标,进而避免交通事故发生。

黑山铁矿井下采场切割与回采过渡期损失贫化控制方法

针对黑山铁矿无底柱分段崩落法开采切割与回采过度期矿石损失贫化大的问题,分析了该时期盲区块产生及矿石损失贫化大的原因,认为下水平切割边壁对上水平布孔阻隔作用,生产中单方面考虑切割槽空间补偿作用而增大自由空间,忽略了切割边壁对上水平的后续影响,是造成扇形自由面失效形成盲区块的主要原因。由于大块主要聚集在放出体顶部,随着放矿的进行,大块提前到达眉线,不得不组织下一次爆破,导致二次矿量损失;同时,大块的存在导致其上部覆盖层小块废石沿着块体间空隙先到达出矿口,造成矿石贫化率较大。从消除盲区块与控制矿石损失贫化角度入手,根据上下水平切巷投影情况,明确了每种情况下的过渡关系,并根据上下两水平切割巷位置关系,提出了合理优化切割巷布孔参数及有效消除盲区块的矿石损失与贫化控制方法。通过现场实践,黑山铁矿井下采矿切割与回采过渡期矿石贫化率与损失率分别降低26.2%与29.3%,同时为类似条件矿山生产提供了借鉴。

黄土高速铁路路基注浆扩散范围模型试验研究

为研究黄土高速铁路路基注浆加固中浆液扩散规律,以大西高速铁路沿线典型湿陷性黄土路基为研究对象,开展注浆模型试验及Edem-Fluent耦合数值仿真,得到黄土注浆扩散范围及注浆盲区参数。试验结果表明:随着注浆压力的增大,浆液的扩散范围逐渐扩大,加固体长度与注浆压力近似幂指数关系。Edem-Fluent耦合仿真分析得到的注浆扩散范围与试验相符合。力链分析表明注浆压力越大,土体间的微观作用力作用越分散,在浆液劈裂方向上,注浆压力是呈消散分布。在此基础上推导了黄土注浆浆液扩散范围及注浆扩散盲区计算公式。

基于紫外脉冲法的绝缘子污秽状态监测

为及时监测绝缘子的污秽状态,根据绝缘子污秽程度与放电脉冲的关系和绝缘子放电时紫外脉冲的特性,提出了一种基于紫外脉冲法的绝缘子污秽状态在线监测技术,通过绝缘子放电强度和次数的变化判断绝缘子污秽程度。110kV线路试验的结果表明,在线监测表面放电时的紫外脉冲可监测绝缘子的污秽状态,且不需接触绝缘子,与绝缘子的距离可以达到4m。