单轴双轮自平衡小车的设计研究

通过物理建模得到了单轴双轮自平衡系统的运动学特性,并结合传感器技术和自动控制理论提出了新的单轴双轮自平衡小车的设计方案.采用陀螺仪和加速度传感器分别对车体倾角进行检测,利用对称互补滤波算法对检测到的数据进行融合得到精确的车体倾角,再引入PID技术对车体姿态进行精确控制.设计的单轴双轮自平衡小车车体的倾角的获取不依赖于小车所处的环境,可在实验过程中调整参量,具有普遍的适用性.     

基于产业关联分析的日本北九州产业结构调整

产业结构调整体现了经济发展的客观要求。日本北九州1990年到2000年的产业关联系数变化趋势,反映了其产业结构调整的特征：产业素质高级化。如何认识和借鉴北九州产业结构调整的经验,对加快实现我国产业结构的优化具有重要启示。     

Interlaminar Crack Propagation Analysis of ENF Specimens Based on the Cohesive Zone Model北大核心CSCD

Based on the classical laminated plate theory and the cohesive zone model, a theoretical model for general delamination cracked laminates was established for crack propagation of pure mode Ⅱ ENF specimens. Compared with the conventional beam theory, the proposed model fully considered the softening process of the cohesive zone and introduced the nonlinear behavior of ENF specimens before failure. The predicted failure load is smaller than that under the beam theory and closer to the experimental data in literatures. Compared with the beam theory with only fracture toughness considered, the proposed model can simultaneously analyze the influences of the interface strength, the fracture toughness and the initial interface stiffness on the load-displacement curves in ENF tests. The results show that, the interface strength mainly affects the mechanical behavior of specimens before failure, but has no influence on crack propagation. The fracture toughness is the main parameter affecting crack propagation, and the initial interface stiffness only affects the linear elastic loading stage. The cohesive zone length increases with the fracture toughness and decreases with the interface strength. The effect of the interface strength on the cohesive zone length is more obvious than that of the fracture toughness. When the adhesive zone tip reaches the half length of the specimen, the adhesive zone length will decrease to a certain extent. Copyright ©2022 Applied Mathematics and Mechanics. All rights reserved.     

矩形坯三角区裂纹的成因与控制

针对Q235钢矩形坯出现的三角区裂纹,通过低倍分析、数值模拟等方法研究了裂纹的特征、成因,并讨论了工艺条件对裂纹的影响.结果表明,三角区裂纹的产生与铸坯鼓肚、窄面凹陷密切相关.降低窄面水量、优化二冷配水制度、改进喷嘴质量能够有效控制矩形坯三角区裂纹.     

热塑性淀粉/聚丁二酸丁二醇酯合金的制备和结构性能表征

制备了高填充的甘油塑化淀粉（GTPS）/聚丁二酸丁二醇酯（PBS）合金,并对其结构性能进行了表征。结果表明：GTPS/PBS在合金加工过程中其扭矩以及力学性能随PBS质量分数的增加及甘油质量分数的减小而增大;扫描电镜（SEM）显示甘油可提高合金的相容性;动态力学分析（DMA）表明合金在玻璃态时的储存模量高于纯PBS,黏流态时则相反;合金的热稳定性随PBS和甘油质量分数的增加而有所提高;PBS的加入将合金的吸水率由100%以上降低到10%以下;淀粉和甘油的存在则均可提高PBS的降解率。     

分布式光网络中的波长和端口数目优化分析

研究了分布式Mesh光网络中动态业务疏导问题中的波长和端口优化问题,通过对分布式Mesh光网络中不同业务和网络拓扑情况下的网络结点波长和端口使用数目的仿真分析,得出网络中的合理波长和端口数目配置,为网络规划和设计提供依据.     

三元团簇X_3(X=S,Se,Te)的结构与芳香性(英文)

使用B3LYP,MP2和CCSD(T)3种方法研究了三元团簇X3(X=S,Se,Te)的几何结构,振动频率,原子化能和总能量.计算的核独立化学位移(NICS)指出在三元结构上存在强的电子环流.详细的分子轨道分析指出有一个高度离域化的σ和一个π分子轨道,它们在多重芳香性中有重要的作用.     

多泵浦光纤喇曼放大器的模拟分析

通过使用综合理论模型对不同配置条件下的多泵浦分布式光纤喇曼放大器的增益谱进行了数值模拟研究,该理论模型包含了瑞利散射、放大自发辐射和不同交互效应,包括泵浦与泵浦、泵浦与信号和信号与信号之间的交互与能量转移.模拟研究了泵浦源功率、泵浦源波长间隔及光纤损耗对喇曼增益谱的影响,结果表明设计多泵浦光纤喇曼放大器需要对泵浦源功率、泵浦源波长间隔光纤损耗谱进行综合考虑,需对泵浦源功率、泵浦源波长间隔进行合理配置.在本文的泵浦源波长设定条件下,考虑实际光纤的损耗谱特性,为了获得大的增益带宽和小的增益不平坦度,短波长泵浦源和最长波长的泵浦源需要更高的泵浦功率,中间波长泵浦源的功率应较低.     

Performance analysis of a novel architecture for contention resolution of OPS

Optical packet switching (OPS) technology can rapidly deliver the enormous network bandwidth and offer high-speed data rate and format transparency. In this paper we propose a novel architecture using all-optical tunable wavelength converters (TWCs) and fiber delay-lines (FDLs) to address the contention problem for OPS in wavelength and time domains. This architecture improves packet switching speed but significantly decreases the number of optical switches comparing with existing architectures. A simulation is also conducted to evaluate the performance of the architecture. The simulation results show that the packet loss probability of this architecture is lower than general architectures.