La掺杂BaTi_2O_5薄膜的制备及性能

采用溶胶-凝胶法在Pt/Ti/SiO2/Si衬底上成功制备了不同摩尔分数La掺杂BaTi2O5薄膜。研究了不同La掺量的BaTi2O5(Ba1-xLaxTi2O5)薄膜的物相组成、介电性能和铁电性能。XRD分析结果表明,采用溶胶-凝胶法经过850℃退火制备的Ba1-xLaxTi2O5(0≤x≤0.01)薄膜样品结晶较好,无杂相出现。La掺杂提高了薄膜的介电性能和铁电性能,当掺杂量0.004≤x≤0.008,测试频率为1MHz时,薄膜的介电常数约为630;当x=0.004时,掺La的BaTi2O5薄膜的剩余极化值最大,2Pr=2.1μC/cm2。     

全地形车车架静动态特性分析与轻量化设计

利用Hyper Mesh有限元软件建立某全地形车车架结构有限元模型,并运用RADIOSS分析其在多种工况下的应力分布和变形情况,校核了该车架的强度和刚度。通过RADIOSS求解器计算其自由模态,与已有的实验模态频率进行对比,验证了有限元模型的正确性。在满足车架强度、刚度和1阶频率的前提下对车架进行结构优化,使该全地形车车架减重5.05kg,达到了轻量化的目的,也验证了尺寸优化在结构优化中的有效性。     

基于模糊评判的中小微企业银行贷款风险控制

通过分析影响中小微企业银行贷款的诸多风险因素,建立层次分析模型,利用模糊评判和指数标度,构建中小微企业银行贷款风险控制指标体系。     

物面倾斜对激光三角法测量误差影响的分析研究

针对传统方法测量位移时出现的分辨率低、准确性差、操作不便捷等问题,提出采用激光三角法非接触测量物体位移,而物面倾斜是影响测量精度的主要因素。通过分析激光三角测量的基本原理,基于朗伯定律,利用光散射原理研究了物面倾斜角与光能质心之间的关系;由沙氏条件下的几何光路关系,推导得到测量误差与倾斜角之间的关系式;通过实验数据对激光扫描测量产生的误差进行分析,验证理论推导的结果,在测量中具有避免出现粗大误差的实际意义。     

重访Duffing系统中的对称破裂分岔与激变

借Duffing系统在简谐激励下发生的对称破裂分岔与激变的实例分析,推介对称系统非线性动力学现象的特色及其研究对策;解释了混沌鞍在混沌动力学分析中的作用。研究表明:周期解的对称破裂分岔只需通过一次鞍结分岔就可直接实现。而混沌吸引子的对称破裂激变往往需要通过边界激变、内部激变与吸引子融合激变等组合手段方能实现。     

Micro-motion feature analysis and parameter estimation methods for moving ship

Micro-motion parameter estimation is an important way to improve ability of radar to detect the ship target. Focusing on the difficulty and speed problems existing in the current parameter estimation method of a complex moving ship, based on the analytical result of the echo's time-frequency features, a novel method to estimate the micro-motion period by calculating the backward shift cross-correlation coefficients of the echo's sparse time-frequency matrix is proposed in this paper. Firstly, the backward shift cross-correlation coefficients of the echo's sparse time-frequency matrix are calculated using the FFT (fast Fourier transform) algorithm. The peaks positions of the cross-correlation coefficients matrix are then detected. Finally, the period can be figured out quickly. Compared with the general method, the proposed method can estimate the micro-motion period accurately and quickly. A computer simulation is given to illustrate the effectiveness of the proposed method.     

Optimization algorithm for dynamic spectrum access based on Q-learning in cognitive radio networks

Under the centralized cognitive radio network architecture, considering the network performance and users' demands. We propose an optimized dynamic spectrum access algorithm based on Q-learning. The proposed algorithm has two steps, which consist of user request according to Q-learning and the application process according to the overall system performance. Simulation results show that the proposed scheme can improve the overall system performance obviously, and that the user requirements could be satisfied at the same time.     

气流式微注射器萃取与气相色谱-质谱联用直接分析烟叶中菊酯类农药

将气流式微注射器萃取技术(GP-MSE)与气相色谱-质谱(GC-MS)联用,建立了一种快速、简单的检测烟叶中菊酯类农药的方法,并通过优化萃取条件和加标回收率实验评价了方法的准确性.结果表明,6种菊酯类农药的加标回收率在83.56%~95.87%之间,相对标准偏差在1.3%~7.6%之间,具有很好的回收率与重复性,说明本文方法可用于检测烟叶样品中的菊酯类农药.     

基于用户喜好的个性推荐系统优化

采用协同过滤方式的传统推荐系统具有一定实用性,但也存在未考虑用户个性喜好的问题。为提高推荐精度,特别针对用户个性化特点和需求,提出了采用改进相似度计算和回归分析方法对协同过滤推荐进行系统优化。实验结果表明,优化算法可明显改善系统的推荐效果,并加强基于协同过滤推荐的有效性。     

Optimal tracking control for automatic transmission shift process

In order to improve the shift quality, a linear quadratic optimal tracking control algorithm for automatic transmission shift process is proposed. The dynamic equations of the shift process are derived using a Lagrange method. And a powertrain model is built in the Matlab/Simulink and verified by the measurements. Considering the shift jerk and friction loss during the shift process, the tracking trajectories of the turbine speed and output shaft speed are defined. Furthermore, the linear quadratic optimal tracking control performance index is proposed. Based on the Pontryagin's minimum principle, the optimal control law of the shift process is presented. Finally, the simulation study of the 1-2 upshift process under different load conditions is carried out with the powertrain model. The simulation results demonstrate that the shift jerk and friction loss can be significantly reduced by applying the proposed optimal tracking control method.