对称矩阵和反对称矩阵的若干性质

在高等代数中矩阵是研究问题很重要的工具，在讨论矩阵转置时给出了对称矩阵和反对称矩阵的定义，但对它们的性质研究很少。对称矩阵和反对称矩阵作为特殊矩阵无论在矩阵理论方面，还是在实际应用方面都有重要的意义。我们在研究矩阵及学习有关数学知识时，经常要讨论这两种特殊矩阵的性质。本文先给出对称矩阵和反对称矩阵的定义，然后讨论了它们的若干性质。     

Influence of residual stress on stress concentration factor for high strength steel welded joints

In this study, a set of plate-to-plate T and Y joints specimens made from high strength steel plates with yield stress equal to 690 MPa is investigated. The joints are fabricated by SMAW welding procedure. Two groups of specimens with different welding procedures are included: one group is composed by the joints with welding completed at ambient temperature and the other group is composed by the joints with welding completed at a preheating temperature of 100 °C. The residual stress near the weld toe is investigated for both groups. Hole-drilling method is applied to investigate the residual stress distribution and variation in joints. Sequentially coupled thermal-stress analysis is then conducted with finite element package ABAQUS to investigate the residual stress distribution in the joints. Finally, the effects of residual stress on the stress concentration factor distributions of the joints are evaluated. A new parameter is put forward in stress concentration factor evaluation to combine the residual stress effect.     

保密传真通信系统的仿真实现

实际的保密传真通信系统是一个功能结构复杂的系统。在建立新系统前，通常需要对系统进行建模和仿真以消除系统中潜在的瓶颈，提高系统成功的概率。文中在分析了保密传真通信系统的工作原理之后，对保密传真通信系统的信源编码模块、加解密模块和调制解调模块进行了Matlab仿真实现，仿真结果达到了预期目标。     

由2自由度并联髋关节构成的脊柱式四足步行机器人步态规划和稳定性分析

针对四足机器人研究中的承载能力低、行走平稳性差问题,设计了一种由2自由度并联髋关节构成的脊柱式四足步行机器人。采用解析几何法和坐标变换法对机器人站立腿和摆动腿进行运动学建模,根据足端位置逆解求得了髋关节变量,进而提出一种无膝关节四足机器人的直行步态、定点转向步态和爬楼梯步态规划方法。基于运动学模型和步态规划方法,通过数值仿真分别得到步态周期内瞬时稳定裕度数据和重心高度变化数据,结果表明四足机器人有较好的稳定性。机器人步态试验验证了该步态规划方法的合理性和有效性。     

相关K分布法在氧气吸收被动测距中的应用

为快速、准确地解算氧气吸收被动测距技术中氧气吸收率所对应的路径长度,对该项技术中氧气吸收率与路径长度的数学模型进行了研究。首先证明了不同温度压强下氧气吸收系数分布的强相关性,给出了吸收系数分布随温度和压强的变化规律;其次利用相关K分布法和曲面地球模型建立了实际非均匀路径上氧气吸收率与路径长度的数学模型;最后对提出的模型进行了理论分析与实验验证。结果显示:本文数学模型不仅能够很好地适应不同大气模式的变化,而且能够快速、准确地计算出指定路径上的氧气吸收率曲线和目标距离;平均数学模型下的相对测距误差为4.4%,消除背景减小测量误差后数学模型解算距离的相对误差仅为1%。结论表明:利用相关K分布法建立的数学模型能够很好地解决氧气吸收被动测距技术中的距离反演问题,可为被动测距技术的进一步优化和应用提供理论支撑。     

PPARγ基因外显子6多态性与PCOS的相关性研究

目的探讨过氧化物酶体增殖物激活受体7（PPAR7）基因外显子6多态性与多囊卵巢综合征（PCOS）的关系。方法抽取中国汉族111例PCOS患者（PCOS组）和92例非DCOS女性患者（对照组）静脉血;特异引物聚合酶链反应（PCR）扩增后限制性酶切（PCR—RFLP）,电泳分离,检测PPARγ基因外显子6的多态性,并分析其与P—COS患者各项临床特征的关系。结果PCOS组中CT／TT基因型频率、T等位基因频率明显高于对照组（P〈0．01）;PCOS患者中PPARγ基因外显子6突变者BMI、腰围、臀围、空腹血糖明显高于未突变者（P〈0．05）,肥胖型PCOS患者中突变（CT／TT）明显高于非肥胖型PCOS患者（P〈0．05）。结论PPAR7基因外显子6的多态性与PCOS肥胖的发生、空腹血糖升高有关。     

基于Matlab GUI的串口通信编程实现

Matlab不仅具有强大的科学计算功能,还内置了GUI工具用于进行界面开发。利用Matlab的GUI工具和内置的串口通信API,设计开发一个可视化的串口通信例程,实现IMU原始数据的接收采集,并利用Matlab强大的科学计算功能,对数据进行实时处理,图形化显示数据处理结果。最后介绍了编译发布Matlab程序的步骤与注意事项。     

有机蒙脱土对天然橡胶/丁苯橡胶的补强及增容作用

采用机械混炼法制备了天然橡胶(NR)/丁苯橡胶(SBR)/有机蒙脱土(OMMT)纳米复合材料,采用TEM和XRD对复合材料的亚微观结构进行了表征,并对复合材料的表观交联密度、静态力学性能、动态力学性能和硫化热效应进行了研究。结果表明,复合材料为剥离型纳米复合材料;OMMT能够明显提高纳米复合材料的交联密度和静态力学性能;OMMT导致NR/SBR共混胶动态损耗因子降低,并且能够促使NR和SBR玻璃化转变温度更为接近,起到了增容作用;OMMT实现了NR和SBR两相的同步硫化。     

Simultaneous tuning of the phase transition temperature and infrared optical properties of Mo-doped VO2 powders for intelligent infrared stealth materials

The development of an intelligent infrared camouflage material whose infrared emissivity can actively adapt to environmental changes is a key frontier in the field of infrared stealth. In this study, Mo-doped VO₂ powder was prepared via a hydrothermal method, which led to an intelligent infrared camouflage material whose infrared radiation characteristic can adaptively change with the environmental temperature. The samples were characterized by XRD, SEM, DSC, FTIR and infrared thermal imaging. Combined with the results of the first-principles calculation, the coupling effect mechanism of Mo⁶⁺ doping concentration on the phase transition temperature and infrared photoelectric properties of VO₂ material was systematically analyzed. The results showed that Mo⁶⁺ impurities had significant effects on the structure, morphology, composition, phase transition temperature and infrared reflectivity of VO₂ powder. The doping process effectively reduced the phase transition temperature of VO₂ and expanded the change range of infrared emissivity (△ε) before and after the metal-to-insulator (MIT) transition. With the increasing amount of Mo⁶⁺ doping, the infrared reflectance of VO₂(M) gradually decreased at low temperatures, while the infrared reflectance of VO₂(R) increased at high temperatures. The MIT transition temperature of Mo-doped VO₂ versus undoped VO₂ reduced to 31.5 °C, and the △ε increased by 153%, this is expected to meet the performance requirements of intelligent infrared stealth materials.     

矿山地质环境影响和土地损毁预测评估研究

为了给矿井生产提供良好的环境空间,研究了矿山地质环境影响和土地损毁预测评估,分析了研究区的地形地貌。基于此,对矿山地质环境影响进行了评估,主要包括评估范围与级别确定、矿山地质灾害、矿区含水层、矿区水土环境污染的现状分析与预测。并对矿山土地损毁进行预测与评估,主要包括土地损毁环节与时序、已损毁各类土地和拟损毁土地预测与评估。研究为促进矿区经济和社会的可持续发展创造了基础。