机器学习在河流流量参数估计中的应用

针对经典水位流量关系模型在刻画河流动态变化特性时存在的局限性,提出采用局部加权回归算法估计河流流量;为了提高参数估计精度,提出一种聚类局部加权回归方法。首先对训练样本进行聚类,然后使用k-最近邻方法将新的水位样本划分进最恰当的聚类中,最后估计河流日流量。该方法在估计过程中,避免了不相关信息的干扰,从而提高了日流量数据估计的效率和精度。利用某水文站的实测数据对方法进行测试,仿真结果表明该方法估计精度较高,为水位流量关系模型参数估计提供了新的有效方法。     

脂肪胺聚氧乙烯醚与LAS复配体系的表面活性

研究了脂肪胺聚氧乙烯醚（AE18）和十二烷基苯磺酸钠（LAS）在水溶液中相互作用。通过表面张力法测定了AE18和LAS不同比例下的临界胶束浓度（CMC）。两种表面活性剂以任何比例复配时,复配体系的CMC都明皿低于LAS的CMC;并且在摩尔比n（LAS）：n（AE18）=1：9时,混合体系的CMC比任何单一表面活性剂CMC都低。复配体系达到CMC时的表面张力（γCNC）介于两种表面活性剂之间。运用Clint提出的理想混合胶团公式对CMC值进行了计算,与CMC实验值比较．发现随AE18摩尔分数的增加,CMC的实验值与计算值相近。     

一种与材料状态相关的砂土剪胀性理论模型

结合密砂和中密砂的相变点的概念,提出了以相变状态为参考状态的状态参量表达式,并将此状态参数引入剪胀比的计算公式.在修正剑桥模型的基础上,提出了新的塑性势函数和硬化参数表达式以消除应力路径的影响.在增量塑性理论的基础上,建立了一种适合于密砂和中密砂的与材料状态相关的剪胀性理论模型.     

利用CAE分析注塑工艺参数对薄壁塑件翘曲形变的影响

利用Moldflow软件,分别模拟分析了模温、熔体温度、保压压力和保压时间对聚丙烯（PP）薄壁塑件翘曲形变的影响。结果表明,总体上来说注塑件在中心处的翘曲量最小,而越靠近注塑件边缘则翘曲变形越大。模具温度从40℃提高到60℃,注塑件中心处的翘曲量变小,而注塑件边缘的翘曲量变化不大。熔体温度从230℃提高到250℃,注塑件的翘曲量减小,且对注塑件边缘的翘曲量影响较大。随保压压力提高,注塑件在总体上的翘曲量减小,而浇口区的翘曲量增加。保压时间过短时注塑件在总体上的翘曲量明显较大;保压时间过长则会引起浇口区的翘曲量变大。     

闭环Boost电路电解电容的故障预测方法研究

为了实现闭环Boost电路中电解电容的故障预测,本文采用基于特征参数退化的方法,利用LS-SVM及LS算法对电解电容的特征参数序列进行预测,实现了电解电容的故障预测与剩余寿命估计.仿真及物理实验均证明了本文方法的有效性及准确性.     

基于动力学理论的轿车悬架参数优化

为提高麦弗逊式独立悬架设计效率,解决悬架的参数对悬架稳定性产生的不良影响,针对某轿车麦弗逊前悬架,应用动力学理论建立轿车的1/4悬架模型,进行车轮随机激励的跳动仿真,验证模型的准确性,然后分别对悬架弹簧刚度、阻尼、前束角、前轮外倾角和主销后倾角进行优化,研究结果表明,该悬架布置方案的优化较好地解决了模型的不合理性.     

基于DSP他励直流电机模糊PID控制器仿真研究

针对他励直流电机调速系统参数模型的非线性、时变性,常规PID控制器参数离线整定带来的非优化的问题,提出一种基于DSP的模糊PID控制器算法,以电流反馈误差及误差的变化率作为模糊控制器的输入变量,采用参数自整定的模糊PID控制器实现PID参数在线优化。以DSP开发系统作为仿真平台,将他励直流电机传递函数转换为差分方程,构成基于模糊PID控制器的数字闭环他励直流电机仿真系统。利用DSP高速运算能力进行在线仿真,观察常规PID控制器和模糊PID控制器产生的系统输出波形。CCS2.0和MATLAB仿真实验表明：模糊PID控制器基本实现输出无超调,系统阶跃响应的上升时间和调整时间均比常规的PID控制器阶跃响应的小。模糊PID控制器应用于他励直流电机调速系统中,控制性能明显高于基于常规PID的调速系统。     

Designing similarity measurement with distance measure and application on laterally directional mode flight test

Similarity measure construction has been proposed as fault detection of flight test method in order to obtain the primary control surface stuck and the combination stuck of primary control. Similarity measures were obtained through analyzing the certainty and uncertainty of fuzzy membership functions, which were designed based on well-known Hamming distance. It was applied to the fault detection of primary control surface stuck of uninhabited aerial vehicle (UAV). At post-failure control surface, if the UAV is controllable and trimmable using other control surfaces, the UAV is able to fly or return to the safety region through reconfiguration of flight control system. To detect the fault, similarity measure computations were carried out. This result could be applicable with the real-time parameter estimation method. By monitoring the value of coefficients due to the control surface deviation, it becomes aware that the control surface fault occurs or not. The control surface stuck position and value were separated by comparing the trim value with the reference value. This is the advantage of increasing in reliability without adding sensors or with additional low cost.     

A modeling method of microburst based on multiple vortex ring

Microburst is a special kind of low-level wind shear, which may do great damage to aircrafts. Modelling of a microburst is significant for flight simulations. In this paper we adopt multiple vortex ring principle to model microburst and propose a new parameter selection method of multiple vortex ring model. We treat the parameters selection as an optimization problem, and introduce the differential evolution algorithm into it. A nested differential evolution algorithm is proposed to complete the two optimization process, objective optimization and intermediate optimization. The simulation results show that this method can flexibly generate microburst with any maximum wind velocity.