摘要：3D点云由于其无序性以及缺少拓扑信息使得点云的分类与分割仍具有挑战性.针对上述问题,我们设计了一种基于自注意力机制的3D点云分类算法,可学习点云的特征信息,用于目标分类与分割.首先,设计适用于点云的自注意力模块,用于点云的特征提取.通过构建领域图来加强输入嵌入,使用自注意力机制进行局部特征的提取与聚合.最后,通过多层感知机以及解码器-编码器的方式将局部特征进行结合,实现3D点云的分类与分割.该方法考虑了输入嵌入时单个点在点云中的局部语境信息,构建局部长距离下的网络结构,最终得到的结果更具区分度.在ShapeNetPart、RoofN3D等数据集上的实验证实所提方法的分类与分割性能较优.

摘要：从局部离散流场数据点重构全局流场信息对数据中心机房的节能节碳具备重要的研究意义。基于局部散点对数据中心进行气流组织温度场快速重构,可有效降低数据中心总能耗。主要通过发展一种基于多特征输入的三维U形神经网络架构(U-net),利用布设在数据中心机房的温度传感器数据值进行气流组织温度场重构。并研究了在不同学习率与数据集大小的设置下,该机器学习模型的训练预测能力。对比结果表明:不同学习率对于模型训练的结果有较大影响,应通过预实验选取最佳学习率。在同等条件下,应优先选取较大的数据集进行训练,便于提取高维物理特征。

摘要：A type of millimeter-wave antenna array with flexible design is proposed for a variety of applications at 60 *** antenna array can be adjusted to be linearly or circularly polarized by simply changing the radiation part of the antenna *** gain,wideband,and high radiation efficiency characteristics can be achieved by adopting a low insertion loss feeding network and broadband antenna *** the linearly polarized antenna array,simulation results show that the impedance bandwidth of the 2×2 antenna subarray reaches 21.6%,while the maximum gain achieves 15.1 dBi and has a fluctuation of less than 0.4 dBi within the working *** results of the 8×8 linearly polarized antenna array show a bandwidth of 21.6%and a gain of(26.1±1)dBi with an antenna efficiency of more than 80%.For the 8×8 circularly polarized antenna array,simulation results show that an impedance bandwidth of 18.2%and an axial ratio(AR)bandwidth of 13.3%are *** and efficiency of up to 27.6 dBi and 80%are achieved,respectively.A prototype of antenna array is fabricated,and results are compared and analyzed.

摘要：建立小熊猫紫色色杆菌PCR快速检测方法,根据紫色色杆菌毒力T3SS效应因子OspC家族蛋白的基因编码序列设计特异性引物,通过反应条件优化,引物特异性、灵敏性和重复性试验,建立PCR快速检测方法并应用于小熊猫病料和兽舍环境样品检测。结果表明,该PCR方法能特异性检测小熊猫紫色色杆菌,从小熊猫饲养环境和死亡小熊猫体内分离出其他菌株未扩增出条带;最低可检测出0.98 pg/μL的紫色色杆菌DNA,具有较好的重复性;用该检测方法从饲养环境和小熊猫病料中检测到的结果与传统的分离培养和测序比对的结果一致。所建立的PCR方法在实际应用中可快速高效检测出紫色色杆菌,可用于小熊猫紫色色杆菌病病原的检测。

摘要：制动软管是轨道车辆空气制动系统的重要组成部件,起到传递和存储制动风压的重要作用,其工作性能直接影响轨道车辆的制动安全.为此,本文针对地铁车辆典型软管结构开展了涵盖拉伸与弯曲力学性能的试验研究,通过对软管结构进行横向、纵向标准取样,对试样的初次断裂应力、二次断裂应力与拉伸伸长率等力学参数进行了对比分析;通过设计适用于不同尺寸规格的圆盘量具,测量并评估了不同规格软管在不同弯曲半径下的椭圆短径与外径变化率,确定了制动软管实车使用及扭转疲劳试验的最佳软管长度.研究成果为轨道车辆制动空气软管的设计选型和试验评估提供了科学依据和技术支撑.

摘要：为解决强采动条件下巷道大变形难题,以新上海一号矿1806N工作面辅运顺槽为工程背景,采用实地勘探、理论分析、数值模拟的方法分析强采动巷道变形破坏原因及围岩大变形机理,提出相应的控制对策进行现场工业性试验。研究发现:1806N工作面辅运顺槽大变形主要影响因素为岩石强度低、节理裂隙发育、完整性差、顶板富水严重、围岩遇水泥化,强采动高集中应力。基于围岩大变形断顶控制机理,形成辅运顺槽深部爆破定向预裂断顶结合补强加固的设计方案。借助数值模拟对断顶及未断顶巷道应力变化规律进行对比分析,断顶巷道端头最大垂直应力14.6 MPa,断顶后巷道端头最大垂直应力12.5 MPa,断顶后端头处垂直应力减小14%,断顶具有一定切断应力传递及减小巷道收缩的效果。开展现场工业性试验,断顶后端头顶底板位移减小37%,两帮变形减小19%,底臌发育长度减小92%,结果表明断顶可有效减少端头巷道变形以及超前底臌发育长度和高度,可为相似工程地质条件巷道建设提供参考。

摘要：The immersed tube tunnel section of the Shenzhen-Zhongshan Link exhibits complex geological conditions and high back sludge strength. The tunnel cushion adopts the gravel and flaky stone combined cushion. The major influencing factors of the mechanical deformation characteristics of the gravel and flaky stone composite cushion are studied through a physical model experiment. The following results are reported.(1) The load–settlement curves of the flaky stone cushion become more compact with a dense increment under the design load. These curves can be regarded as nonlinear mechanical characteristics. The load–settlement curves of the gravel cushion and the gravel and flaky stone composite cushion exhibit the characteristics of a two-stage linear change.(2) The flatness of the top of flaky stone cushion considerably affects settlement and secant modulus. The flatness of the top of flaky stone should be ensured during construction.(3) Gradation and thickness exert no evident effect on the compressibility of a cushion. The preloading pressure caused by the construction height difference of the cushion materials plays an important role in improving the initial stiffness of a cushion and reducing initial settlement and overall settlement.(4) This study investigates the preloading under 30 kPa of the 0.7-m flaky stone and 1.0-m gravel combination cushion. It recommends the following secant modulus values: 48.89 MPa for the section of 0–30 kPa and 10.47 MPa for the section of 30–110 kPa.

摘要：Variable stiffness composite laminates(VSCLs)are promising in aerospace engineering due to their designable material properties through changing fiber angles and stacking *** to control the thermal postbuckling and nonlinear panel flutter motions of VSCLs,a full-order numerical model is developed based on the linear quadratic regulator(LQR)algorithm in control theory,the classical laminate plate theory(CLPT)considering von Kármán geometrical nonlinearity,and the first-order Piston *** critical buckling temperature and the critical aerodynamic pressure of VSCLs are parametrically *** location and shape of piezoelectric actuators for optimal control of the dynamic responses of VSCLs are determined through comparing the norms of feedback control gain(NFCG).Numerical simulations show that the temperature field has a great effect on aeroelastic tailoring of VSCLs;the curvilinear fiber path of VSCLs can significantly affect the optimal location and shape of piezoelectric actuator for flutter suppression;the unstable panel flutter and the thermal postbuckling deflection can be suppressed effectively through optimal design of piezoelectric patches.

摘要：普鲁士蓝(PB)材料及其类似物(PBAs)具有理论容量高、离子交换能力优越、电化学稳定性好等优势,被广泛应用于环境等诸多领域,具有重要研究意义。结合近年来的研究热点,综述了普鲁士蓝及其类似物在电池、环境、医疗、催化剂、检测等领域的研究进展及具体应用,详细介绍了普鲁士蓝的特点与性能优化方法,为重金属吸附剂、比面积优化的电极材料等设计与开发提供了新思路,且为深入了解类普鲁士蓝吸附机理、电催化析氧性能增添了新见解,并结合目前尚存在的不足,对普鲁士蓝材料的未来应用空间和发展前景进行了展望。

摘要：为明确云南省瑞丽雪茄烟区土壤合理施肥方案,采用“3414”肥料试验设计,通过熵权法和回归分析,计算了各处理对应的烟株农艺性状综合得分,探究了N、P、K对雪茄烟株长势和烟叶产量的影响,筛选出最佳施肥方案。结果表明:(1)株高对雪茄烟株农艺性状的得分所占权重最大,处理6(N_(2)P_(2)K_(2))对应的得分最高。(2)在一定范围内增加N、P、K的施用量,对雪茄烟的产量有积极作用,然而随着施肥量的增加产量又有所下降。(3)构建了N、P、K施用量对雪茄烟产量的二元二次和三元二次回归模型,最佳施肥方案为N施用量在118.7~126.9 kg/hm^(2)之间,P_(2)O_(5)施用量在75.7~81.4 kg/hm^(2)之间,K_(2)O施用量在342.1~366.5 kg/hm^(2)之间,目标产量在1816.3~1812.5 kg/hm^(2)之间。