The operating principle of a lead screw linear ultrasonic motor using bending vibration modes is analyzed. The simplified beam bending vibration model is used to analyze the dynamics characteristics of the motor. Moti...The operating principle of a lead screw linear ultrasonic motor using bending vibration modes is analyzed. The simplified beam bending vibration model is used to analyze the dynamics characteristics of the motor. Motion trajectory equations are derived for driving points of the stator. The motor operation and driving mechanisms are investigated. The vibration modes and the construction of the motor are analyzed by using the finite element method （FEM）. A prototype motor is built and its stator dimension is 13 mm × 13 mm× 30 mm. The motor is experimentally characterized and the maximum output force of 5- 2 N is obtained.展开更多
The structure and the acoustic medium of a passenger vehicle are modeled using the finite element method(FEM), and the interior noise is studied the help of the modal synthesis method (MSM). Sound pressure level (Lp) ...The structure and the acoustic medium of a passenger vehicle are modeled using the finite element method(FEM), and the interior noise is studied the help of the modal synthesis method (MSM). Sound pressure level (Lp) of the noise is calculated in several conditions of the models, and has good agreements with its test results. The MSM am be consequently used for predicting the vehicle interior noise in dssign stage so that the structure may be optimized for the Purpose of the most reduction of noise.展开更多
文摘首先通过声振无损检测系统获取香梨响应信号,对信号进行经验模态分解并采用不同方法抑制其端点效应和模态混叠以实现信号分解效果最优;然后将香梨声振信号分解的分量作为输入,构建基于空间金字塔池化的卷积神经网络(convolutional neural networks with space pyramid pooling,CNN-SPP)判别模型。结果表明,改进斜率法能更有效抑制香梨声振信号分解端点效应,进一步采用互补自适应噪声完备集合经验模态分解(complementary complete ensemble empirical mode decomposition with adaptive noise,CCEEMDAN)方法可获得模态混叠抑制最佳的信号分量,以此为输入构建CCEEMDAN-CNN-SPP判别模型对香梨黑心病的总体分类准确率为93.66%,对亚健康香梨判别准确率达94.44%,病害果误判率为6.35%,提高了声振法对梨果早期轻度病害的判别精度,为声振法应用于亚健康水果在线检测系统研发提供了研究基础。
基金Supported by the National Natural Science Foundation of China(50575103, 50735002)~~
文摘The operating principle of a lead screw linear ultrasonic motor using bending vibration modes is analyzed. The simplified beam bending vibration model is used to analyze the dynamics characteristics of the motor. Motion trajectory equations are derived for driving points of the stator. The motor operation and driving mechanisms are investigated. The vibration modes and the construction of the motor are analyzed by using the finite element method （FEM）. A prototype motor is built and its stator dimension is 13 mm × 13 mm× 30 mm. The motor is experimentally characterized and the maximum output force of 5- 2 N is obtained.
文摘The structure and the acoustic medium of a passenger vehicle are modeled using the finite element method(FEM), and the interior noise is studied the help of the modal synthesis method (MSM). Sound pressure level (Lp) of the noise is calculated in several conditions of the models, and has good agreements with its test results. The MSM am be consequently used for predicting the vehicle interior noise in dssign stage so that the structure may be optimized for the Purpose of the most reduction of noise.
