Longitudinal train dynamics of electric multiple units under rescue

Once operating trains are disabled on the railway lines,an efficient manner is to utilize the train for train rescue.Owning to the different train and coupler types,it is difficult to formulate uniform regulations for train to train rescue.In this paper,the longitudinal train dynamics of electric multiple units under rescue were analyzed by field and laboratory tests.The angling behavior of the brakinginduced coupler under compressed in-train forces was analyzed.A dynamic model for the train and draft gear system was developed considering accurate boundary limitations and braking characteristics.The safety indices and their limits for the coupled rescue train were defined.Thedynamic evaluations of different train to train rescue scenarios were analyzed.It is indicated that the coupler vertical rotation occurs during the emergency braking applied by the assisting train.The vertical force components of intrain forces lead to the carbody pitch behavior and even cause local destructions to the coupler system.The carbody pitch motion can arise the inference of in-train devices.Based on the safety evaluation of train and coupler system,the regulations for typical train to train rescue scenarios were formulated.

Feasibility of replacing the 3-coach with a 1.5-coach grouping trainmodel in wind tunnel experiment at different yaw angles

The effects of different yaw angles on the aerodynamic performance of city electric multiple units(EMUs)were investigated in a wind tunnel using a 1:16.8 scaled model.Pressure scanning valve and six-component box-type aerodynamic balance were used to test the pressure distribution and aerodynamic force of the head car respectively from the 1.5-and 3-coach grouping city EMU models.Meanwhile,the effects of the yaw angles on the pressure distribution of the streamlined head as well as the aerodynamic forces of the train were analyzed.The experimental results showed that the pressure coefficient was the smallest at the maximum slope of the main shape-line.The side force coefficient and pressure coefficient along the head car cross-section were most affected by crosswind when the yaw angle was 55°,and replacing a 3-coach grouping with a 1.5-coach grouping had obvious advantages for wind tunnel testing when the yaw angle was within 24.2°.In addition,the relative errors of lift coefficient C_(L),roll moment coefficient C_(Mx),side force coefficient C_(S),and drag coefficient C_(D) between the 1.5-and 3-coach cases were below 5.95%,which all met the requirements of the experimental accuracy.

Passive Localization of Multiple Sources Using Joint RSS and AOA Measurements in Spectrum Sharing System

In spectrum sharing systems,locating mul-tiple radiation sources can efficiently find out the in-truders,which protects the shared spectrum from ma-licious jamming or other unauthorized usage.Com-pared to single-source localization,simultaneously lo-cating multiple sources is more challenging in prac-tice since the association between measurement pa-rameters and source nodes are not known.More-over,the number of possible measurements-source as-sociations increases exponentially with the number of sensor nodes.It is crucial to discriminate which measurements correspond to the same source before localization.In this work,we propose a central-ized localization scheme to estimate the positions of multiple sources.Firstly,we develop two computa-tionally light methods to handle the unknown RSS-AOA measurements-source association problem.One method utilizes linear coordinate conversion to com-pute the minimum spatial Euclidean distance sum-mation of measurements.Another method exploits the long-short-term memory(LSTM)network to clas-sify the measurement sequences.Then,we propose a weighted least squares(WLS)approach to obtain the closed-form estimation of the positions by linearizing the non-convex localization problem.Numerical re-sults demonstrate that the proposed scheme could gain sufficient localization accuracy under adversarial sce-narios where the sources are in close proximity and the measurement noise is strong.

Design of 2D-Bootlace Lens with Five Focal Feed for Multiple Beam Forming

Utility of microwave bootlace lens is well established. For broadband and wide scanning network, it is required to op-timize and use features of this lens for better communication and scanning device. This report presents the design of a compact 2D bootlace lens with five focal feed for multiple beam forming. This design will help in reducing phase error and will provide power efficiency and better resolution during target tracking. This design will provide better aperture efficiency and scanning angle.

慢性病共病、相位角与老年人肌少症相关的肌肉质量减少的关系研究

目的·探讨慢性非传染性疾病(慢性病)共病、相位角与老年人肌少症相关的肌肉质量减少的相关性,以及慢性病共病、相位角对老年人肌肉质量减少的预测价值。方法·对2018年8月1日—2019年7月31日入住上海交通大学医学院附属仁济医院老年科,年龄≥60岁的患者进行回顾性筛查。收集患者基本情况(性别、年龄、用药数、共病数、有无骨质疏松症、有无吸烟史等),以及实验室检查指标(血红蛋白、白蛋白、血肌酐、血尿酸、铁蛋白、维生素D、三酰甘油、总胆固醇、高密度脂蛋白、低密度脂蛋白等)结果。计算年龄调整后查尔森合并症指数(age-adjusted Charlson comorbidity index,aCCI)。采用InBody S10生物电阻抗身体成分检测仪进行人体成分测试,记录身体质量指数(body mass index,BMI)、骨骼肌质量指数(skeletal muscle mass index,SMI)、相位角(phase angle,PhA)。部分患者接受握力测量。肌肉质量减少采用2019年亚洲肌肉减少症工作组(Asian Working Group for Sarcopenia,AWGS)推荐的SMI值(男性≤7.0 kg/m^(2)、女性≤5.7 kg/m^(2))进行诊断。根据测定的SMI值将患者分为肌肉质量正常组与肌肉质量减少组。采用单因素和多因素Logistic分析老年患者发生肌少症相关的肌肉质量减少的危险因素。并进一步运用受试者操作特征曲线(receiver operator characteristic curve,ROC曲线)及曲线下面积评估相关因素预测肌肉质量减少的价值。结果·共入组慢性病共病患者359例,其中男性226例,女性133例;肌肉质量正常组241例,肌肉质量减少组118例,老年人肌少症相关的肌肉质量减少发生率为32.9%。单因素Logistic回归分析提示年龄(OR=1.036,95%CI 1.013~1.060)、共病数(OR=1.117,95%CI1.025~1.217)、aCCI(OR=1.123,95%CI 1.031~1.222)、高密度脂蛋白(OR=3.688,95%CI 2.065~6.622)与老年人肌肉质量减少的风险呈正相关,BMI(OR=0.514,95%CI 0.443~0.597)、PhA(OR=0.195,95%CI 0.126~0.303)、血红蛋白(OR=0.984,95%CI 0.972~0.996)、三酰甘油(OR=0.606,95%CI 0.424~0.866)与老年人肌肉质量减少的风险呈负相关。多因素Logistic回归模型提示PhA(OR=0.338,95%CI 0.119~0.959)、BMI(OR=0.634,95%CI 0.476~0.844)与老年人肌肉质量减少的风险呈负相关。BMI、PhA预测老年人肌少症相关的肌肉质量减少的ROC曲线下面积分别为0.893(95%CI 0.855~0.931)和0.786(95%CI 0.736~0.837),敏感度分别为0.724和0.676,特异度分别为0.916和0.762;BMI联合PhA预测老年人肌肉质量减少的ROC曲线下面积为0.917(95%CI 0.883~0.951),敏感度为0.867,特异度为0.860。结论·aCCI与老年人肌少症相关的肌肉质量减少具有相关性。随着BMI、PhA的下降,老年人肌肉质量减少的风险升高。BMI联合PhA具有较高的老年人肌少症相关的肌肉质量减少的预测价值。未发现慢性病共病对其的预测价值。

基于Raptor编码的多输入多输出光通信系统设计

为了提高可见光通信(Visible Light Communication,VLC)系统的复用增益,本文提出一种基于多输入多输出(Multiple Input Multiple Output,MIMO)的固定比例像素化VLC系统。系统首先执行空间角度映射,使数据的传送可在角域中进行;同时利用Raptor编码方法来跟踪由于窗口截断而引起的数据信道特性变化;然后对于使用高速相机捕捉到的一系列时变图像,利用散景效应获得所有链路距离上的固定比例图像。实验利用液晶显示器和高速相机,对所提出的VLC系统进行了验证。与传统的像素化MIMO系统相比,本文所提出的系统在未对准朝向的情境下具有更高的鲁棒性,从而在多路复用场景有着广泛的应用前景。

汽车中控壳注塑模及其五次六元复合斜滑块设计

汽车中控壳塑件注塑模具设计中,因塑件正面和背面都需要采用斜向脱模方式脱模,特别是背面的特征组成中,特征多且构成复杂,因此为该区域特征的脱模创新设计了一种五次六元复合斜滑块机构在局部区域实施抽芯脱模,并构建了该机构的力学运动模型。该复合斜滑块机构的结构设计为:利用油缸驱动1个主体斜滑块实施主抽芯,主体斜滑块的上端设置了一个先抽芯斜滑块即上斜滑块,上斜滑块先抽芯时驱动3个斜顶、4根弹簧顶针和1个C4侧型芯镶件;主体斜滑块的下端还设置了一个先抽芯斜滑块即斜型芯,该斜型芯也先于主体斜滑块抽芯;在上斜滑块完成先抽芯后,主体斜滑块的驱动油缸先驱动斜型芯抽芯,而后再驱动主体斜滑块及其上其余5种脱模元件一起完成抽芯。为实现塑件的自动化生产,在此复合斜滑块机构设计基础上,塑件的模具结构设计成热流道两板式两次开模模具,模具中还设计了1个正面油缸斜抽芯机构和4个斜导柱滑块机构,较好地实现了塑件的自动化生产。

计及尾流的风电场智能等效建模及偏航优化控制

大型风电场中存在的尾流干扰会降低风电场整体输出功率,因此需要对风电场建立等效模型,并通过优化尾流分布来提升风电场整体功率输出能力。在所提出的新型风电场偏航优化框架中,提出了一种利用参数监督学习和正则化技术改进的径向基函数神经网络算法,并建立了面向多自由度偏航控制的风电场功率转换智能等效模型。在该模型的基础上,定义了以风电机组偏航角为决策变量的场级最大输出功率优化问题,提出了一种改进的精英多种群遗传算法并进行优化求解,得到各机组偏航角优化值以减少机组间尾流干扰。利用实际风电场布局和风况数据进行了仿真测试。结果表明:所建立的风电场功率转换智能等效模型与其实际特性吻合良好,在特定风况下,偏航优化控制使得风电场总功率提升718.79 kW;连续风况下,所提优化控制方法在不同风况下均有明显的优化效果,风电场总功率平均提升1208 kW,验证了所提出的新型风电场偏航优化框架在提升风电场整体输出功率上的优越性。

基于5G信号异步时钟误差补偿的多无人机协同定位方法

5G信号可为多无人机(UAV)提供精确的相对测距/测角信息,进而提升其在卫星接收机故障时的协同定位精度。然而,协同网络中各节点的5G通讯时钟往往是异步的,这会对测距/测角信息的精度产生较大影响,进而降低融合性能。针对上述问题,提出了一种基于5G信号异步时钟误差补偿的多无人机协同定位方法。首先,构建了基于5G信号异步时钟误差的相对测距模型,并利用相对测距/测角信息以及高度计信息建立了从机的位置观测方程。在此基础上,通过设计迭代扩展卡尔曼滤波器(IEKF)实现了对从机惯导系统(INS)误差以及异步时钟误差的联合最优估计,提高了从机定位精度。仿真结果表明,相比于传统方法,所提方法将从机的水平定位精度提高了25.3%。

多无人艇载舷外有源诱饵组合干扰及评估方法

舷外有源诱饵是应对主动雷达制导反舰导弹的重要干扰手段之一,但在使用上,其存在干扰响应时间短且干扰态势要求高的时空局限性。针对这一问题,本文基于无人艇平台,提出了多舷外有源诱饵组合干扰样式,通过无人化与集群化提升舷外有源诱饵的作战效能。首先,根据反舰导弹单脉冲主动雷达导引头的测角原理,从信号层面推导了多诱饵干扰下的角度响应。其次,从态势层面,分析了多诱饵组合干扰的有效性临界条件;接着,结合信号与态势,提出了多诱饵组合干扰评估方法。最后,通过仿真与数值分析,验证了多诱饵对干扰效果的提升作用以及评估方法的可行性,为舷外有源诱饵的集群化干扰提供了理论支撑。

大跨度悬索桥多对刚性中央扣受力性能研究

中央扣对改善大跨度悬索桥动力特性、短吊杆弯折、主梁纵向位移等具有显著作用,但现有文献少见对中央扣自身力学行为的研究。该文以中央扣为研究对象,通过力学方法推导了中央扣侧移刚度的计算公式,通过敏感性分析确认了杆身倾角α以及杆身轴向刚度j是影响中央扣侧移刚度的主要因素;对设置多对刚性中央扣的情况进行了研究,因主缆与中央扣杆身轴向刚度相差不大,主缆对多对中央扣协调受力影响较大,中央扣与主缆组成串、并联弹簧体系,受力分配更加复杂,可通过调整杆身倾角及杆身轴向刚度,设置具有不同侧移刚度的多对中央扣以实现协调受力。

某大跨度带天窗双层网架结构风压分布研究

大跨结构杆件众多,形状较为复杂,而在我国规范中并没有涵盖所有复杂结构设计的相关参数,常导致结构设计时缺少参考依据,因此对大跨空间结构进行抗风设计的研究是很有必要的。以实际工程为背景,采用相对成本更低、效率更高的数值模拟(CFD)方法,对带有天窗的大跨网架结构进行风压研究。以网架结构辅助设计软件STADS与Fluent接口开发程序为基础,完成对带有天窗的网架结构的分区模型建立、数值风场计算域的生成以及计算结果的输出,极大提高了计算效率,最后通过对比分析总结了相应结构的风压分布规律;通过对结构天窗开闭合2种情况下的风压分布对比分析,发现2种结构形式总体风压分布规律一致,局部会有不同,结构开窗能有效降低总体风压值并减小结构所受的风吸力,但会对结构底部压力增大,使结构支座反力增加,为大跨度带天窗类网架结构的设计和施工提供了有利参考。

Multiple rotation averaging using only the relative rotation angle

In this work,we propose multiple rotation averaging using only the relative rotation angle,which is a straightforward camera pose optimization method.We use the axis-angle representation to parameterize the rotation and use only relative rotation angles to constrain absolute rotations instead of complete relative rotations.When used with an inertial measurement unit(IMU),our method can obviate the need to estimate and maintain extrinsic parameters between the camera and IMU.This advantage makes our method immune to extrinsic parameters and flexible.We performed extensive evaluations on both synthetic data and publicly available real datasets,which showed that our method was comparable with the state-of-the-art method and achieved a significant gain in accuracy for the visual measurement when applied to the case in which the camera and IMU are tightly fixed.

基于多空气槽新V型转子超高效NVRPM优化设计

依据指标优化设计一款额定功率22 kW、额定转速3000 r/min的压缩机用内置新V型转子永磁同步电机(NVRPM)。由于V型结构永磁电机较多的永磁体块数造成转子极间漏磁增大,以及气隙磁场含有较大的谐波分量易导致损耗增加、效率降低,在初始V型转子上进行3处结构的优化设计:转子面上添加多空气槽;余弦型非均匀气隙;转子分段斜极式。通过有限元仿真NVRPM的电磁特性,并且计算最佳斜极角、分析非均匀气隙中余弦函数的幅值,证明优化后新电机能够减少损耗22.6%、削弱齿槽转矩98.2%、降低转矩波动11.7%。另外,试制实验样机并测试效率高达96.32%且运行区域宽广高效。因此NVRPM的优化设计具有实践性,适合压缩机生产使用。

Angle estimation in bistatic MIMO radar using improved reduced dimension Capon algorithm

This paper discusses the problem of direction of departure （DOD） and direction of arrival （DOA） estimation for a bistatic multiple input multiple output （MIMO） radar, and proposes an improved reduced-dimension Capon algorithm therein. Compared with the reduced-dimension Capon algorithm which requires pair matching between the two-dimensional angle estimation, the pro- posed algorithm can obtain automatically paired DOD and DOA estimation without debasing the performance of angle estimation in bistatic MIMO radar. Furthermore, the proposed algorithm has a lower complexity than the reduced-dimension Capon algorithm, and it is suitable for non-uniform linear arrays. The complexity of the proposed algorithm is analyzed and the Cramer-Rao bound （CRB） is also derived. Simulation results verify the usefulness of the proposed algorithm.

Suggestion of advanced regression model on friction angle of fault gouge in South Korea

Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than those of soils or rocks due to its high heterogeneity and low strength.Therefore,to improve the accuracy of analysis results,we conducted simple regression analysis and structural equation model analysis and selected major influential factors of friction characteristics among many factors,and then we deduced advanced regression model with the highest coefficient of determination(R^(2)) via multiple regression analysis.Whereas most coefficients of determination in simple regression analysis are below0.3-0.4,coefficient of determination in multiple regression analysis is remarkably large as 0.657.

Non-fluctuating target detection in low-grazing angle with MIMO radar

The non-fluctuating target detection in low-grazing angle using multiple-input multiple-output(MIMO) radar systems was studied, where the multipath effects are very abundant. The performance of detection can be improved via utilizing the multipath echoes. First, the reflection coefficient considering the curved earth effect is derived. Then, the general signal model for MIMO radar is introduced for non-fluctuating target in low-grazing angle. Using the generalized likelihood ratio test(GLRT) criterion, the detector of non-fluctuating target with multipath was analyzed. The simulation results demonstrate that the MIMO radar outperforms the conventional radar in non-fluctuating target detection and show that the performance can be enhanced markedly when the multipath effects are considered.

Multiple Angles Of Approach

The Sixth Beijing Forum on Human Rights was held on September 12 and 13 with the theme being＂construction of an environment for sustainable human rights development.＂The forum attracted more than100officialsandhumanrightsexpertsfromthe United Nations and 33 countries and regions.

新疆大倾角多煤组煤矿区煤层气开发利用进展与前景

煤层气是非常规天然气的重要组成部分,新疆作为我国十四个特大型煤炭产业基地之一,煤层气资源储量丰富,约占全国煤层气资源总量的26%。为分析归纳新疆特殊的大倾角多煤组煤矿区煤层气资源特征,总结了“十三五”以来,新疆煤矿区煤层气开发利用在理论、技术及装备方面取得的突破性研究进展,并对未来新疆煤矿区煤层气开发利用潜力和应用前景作出长远的展望。结果表明:新疆煤矿区资源具有“倾角大、煤层多、煤阶低、含气高”的特征。取得的突破性研究进展主要包括:提出了基于“三孔四区五量”的大倾角多煤组煤矿区时空协同煤与煤层气协调开发模式;阐明了大倾角采动地面井变形模式及高危位置确定方法,提出了“避、抗、让、疏、护”五字理念的地面井设计技术;研发了大倾角碎软煤层下向递进式抽采钻孔成套技术与装备;构建了新疆高寒地区煤层气利用蓄热氧化供暖技术;上述研究成果在现场试验中成功应用,提升了新疆煤矿区煤层气开发利用的整体水平。然而,规模化的煤层气开发利用产业尚未大面积形成。因此,亟需总结推广典型的大倾角多煤组煤矿区三区联动煤层气开发模式;加强多煤组煤矿区的地面井均匀超前预抽;研发井下煤层气高效抽采技术及装备;基于非对称采动卸压作用实现靶向精准抽采煤层气;拓展适用于高寒地区的全浓度范围煤层气利用技术;重点加快推进国家级“新疆准噶尔盆地南缘煤层气产业化基地”建设,实现新疆丰富煤层气资源的规模有效开发利用。

SPSS软件在钻孔弯曲规律预测中的应用研究

随着定向钻进技术应用越来越广泛,钻孔轨迹的控制技术变得尤为重要。为了研究钻孔自然弯曲规律,找到顶角和方位角的变化趋势,进而预测待钻钻孔轨迹的变化,使用SPSS软件对安徽省一号矿区的钻孔测斜数据进行多元方程回归统计分析。在考虑孔深、开孔点空间位置信息(x、y、z坐标)对顶角和方位角影响的基础上,建立了四元八次多项式回归方程,并采用均角全距法,将回归拟合的钻孔轴线空间位置与实际钻孔空间位置进行对比。结果表明:将钻孔原始数据进行线性处理后,用四元八次多项式进行回归,能得到较好的效果,若按照钻孔所处地层产状的不同进行分类后进行回归,拟合程度将进一步提高。利用拟合度高的回归方程,能用来预测未开孔地区的钻孔自然弯曲轨迹,对工程施工控制钻孔轨迹也起到了良好的作用,能更好指导工程的施工。