对称分段线性振子的次谐分叉分析

本文用Poincare映射法导出了对称分段线性振子的一个次谐分叉近似条件。数值仿真表明,由本文分叉条件得出的临界值与数值仿真值很接近。另外,用数值仿真法分析了对称分段线性振子的进一步次谐分叉。     

三阶边值问题解的存在性与唯一性

本文利用上下解方法研究了三阶边值问题解的存在性和唯一性。     

多轴非比例加载下低周疲劳损伤模型

本文用连续损伤力学方法分析了多轴非比例加载下的低周疲劳损伤累积和演化过程,并导出了预测非比例加载下低周疲劳寿命的Coffin-Manson型的修正公式。     

柴油机燃油电控喷射用快速电磁阀的动力学分析

本文分析了快速电磁阀的动力学特性及保证电磁阀快速动作的线圈外施电压波形:进而提出了在实际采用阶梯波外施电压条件下电磁阀动力学特性的计算机模拟计算方法。     

轮-轴组件的三维弹性接触分析

本文根据接触问题的参变量最小势能原理,建立了接触问题的有限元参数二次规划解,并以RE_2型车轴为例,按三维接触模型进行了计算分析。     

APOPTOSIS OF HYPERPLASIA AND CANCER OF THE GALLBLADDER WITH CALCULAS

Ｔｈｅｃａｎｃｅｒｏｆｇａｌｌｂｌａｄｄｅｒｉｓａｃｏｍｍｏｎｍａｌｉｇｎａｎｔｔｕｍｏｒｏｆｔｈｅｂｉｌｉａｒｙｔｒａｃｔ ,ｗｈｉｃｈｉｓｈａｒｄｔｏｄｉａｇｎｏｓｅａｎｄｈａｓａｐｏｏｒｐｒｏｇｎｏｓｉｓ .Ｉｔｉｓａｌｗａｙｓａｃｃｏｍｐａｎｉｅｄｂｙｃｈｏｌｅｃｙｓｔｏｌｉｔｈｉａｓｉｓ .Ｔｈｅ ｐａｔｈｏｌｏｇｉｃａｌｒｅｓｅａｒｃｈｆｏｒｃｈｏｌｅｃｙｓｔｏｌｉｔｈｉａｓｉｓ ,ａｄｉｓｅａｓｅｃｏｍｍｏｎｌｙａｎｄｆｒｅｑｕｅｎｔｌｙｗｅｒｅｆｏｕｎｄｉｎｃｌｉｎｉｃｓ ,ｓｈｏｗｅｄｔ…     

迫导向转向架低锥度失稳问题的研究

本文深入探讨了迫导向转向架所具有的低锥度失稳问题。以三轴、二轴迫导向转向架为对象建立数学模型,分析运动学失稳和动力学失稳两种模式。得到不同导向刚度下产生失稳的临界踏面锥度和不同锥度下的临界速度值。研究发现,通过参数的合理匹配,可使临界锥度降至常见最小锥度以下,从而可以避免低锥度失稳,为迫导向转向架的参数设计提出了一个新的准则。     

MODEL AND SIMULATION FOR A BRUSHLESS AC GENERATOR WITH AROTARY RECTIFIER

Objective For a brushless AC generator with a rotary rectifier, it is necessary and significant to model and simulate at normal and fault operation states. Methods Two new concepts, namely, Simulink signals and PSB (Power System Blockset) variables, are proposed, and the difference between the two concepts is clarified. Based on the new model for synchronous machines, a simulation model for a brushless AC generator with a rotary rectifier is constructed by Matlab/Simulink/PSB. This new model, which has a speed input terminal and an exciting voltage input one, can simulate the real electrical characters and direct mechanical connection between two synchronous machines perfectly. The rotary rectifier is a three-phase full-wave bridge rectifier which consists of six diodes. The model for the diodes is a macro-model which possesses much better accuracy than an ideal one of switches. Results Based on the present model, some simulation results such as exciting current waveform, phase current waveform and phase voltbge waveform are afftained at several operation conditions. Conclusion The simulation for a brushless AC generator with a rotary rectifier is demonstrated at normal and fault operation states, respectively. The results confirm the presented method.     

CLASSIFICATIONS OF EEG SIGNALS FOR MENTAL TASKS USING ADAPTIVE RBF NETWORK

Objective This paper presents classifications of mental tasks based on EEG signals using an adaptive Radial Basis Function (RBF) network with optimal centers and widths for the Brain-Computer Interface (BCI) schemes. Methods Initial centers and widths of the network are selected by a cluster estimation method based on the distribution of the training set. Using a conjugate gradient descent method, they are optimized during training phase according to a regularized error function considering the influence of their changes to output values. Results The optimizing process improves the performance of RBF network, and its best cognition rate of three task pairs over four subjects achieves 87.0%. Moreover, this network runs fast due to the fewer hidden layer neurons. Conclusion The adaptive RBF network with optimal centers and widths has high recognition rate and runs fast. It may be a promising classifier for on-line BCI scheme.     

冷板冷藏车振动分析及隔振措施

建立了冷板冷藏车的动力学模型，运用模态分析方法建立相应的数学模型，分析了冷板冷藏车的振动特性，提出了在刚性冲击前提下的隔振方法。计算分析表明，在刚性冲击前提下所采用的隔振方法可以达到隔振的目的。