产品机械冲击脆值和耐振度研究

综述了破损边界理论及用Ｄｕｈａｍｅｌ积分得到的几种典型脉冲的冲击谱公式和破损边界曲线，提出了产品耐振度的概念．这些结果为产品的机械冲击和振动防护设计提供了理论基础．

解偏振度的测量及偏振成像探测识别

在对解偏振进行定义的基础上,用Mueller矩阵参数元表述了解偏振度,并根据斯托克斯-Mueller矩阵关系式,设计了实验装置测量两种硬币的解偏振度。用线偏振激光作光源、CCD相机做成像探测器的方法对包含有两硬币的目标进行主动成像实验,实验中,采集了六张不同偏振夹角的偏振图像和一张无检偏振器时的图像。实验证明,利用偏振技术并通过选取合适的偏振夹角对目标进行成像的方法,可以有效地提高成像探测的图像对比度,有利于目标的探测与识别。

混频器本振隔离度及增益对数字阵列雷达性能影响分析

根据数字阵列雷达收发链路模型,分析了本振噪声通过混频器隔离度对接收信噪比产生的影响、本振驱动电路增益(简称“本振增益”)在数字阵列雷达中频脉冲信号与本振脉冲信号无法完全对齐的情况下对发射输出波形及频谱产生的影响、本振隔离度及本振增益影响发射链路稳定性的机制,得出数字阵列雷达收发链路的设计应关注本振隔离度及本振增益的结论,以期为对混频器选型、设计以及收发链路的设计提供参考。

各向同性阶跃光纤的偏振椭圆度

利用全反射光在光纤包层中的横向偏移和相位变化 ,导出了各向同性阶跃光纤的全反射偏振椭圆度和偏振椭圆度长度计算公式 。

多自由度阻尼振系动力调谐减振器的参数计算

通过有阻尼多自由度振系幅频响应表达式的分析，获得较准确的最佳减振器结构参数计算公式及完全消振条件．从而实现在无需建立主振系动力学模型的情况下，通过测量主振系动力响应来进行动力调谐减振器的设计计算．

阻振质量阻抑结构声的传递

研究了无限板上受点激励时阻振质量对结构声传递的阻抑 ,采用基于能量观点的隔振度定义阻振质量的阻抑作用 .通过理论分析验证了隔振度简化公式的可行性 ,发现板平面弯曲波分别和阻振质量的弯曲波、扭转波达到最佳耦合时 ,平面弯曲波发生最大透射 .算例分析和试验研究论证了理论分析的正确性 ,为阻振质量应用于结构声传递途径的控制提供了理论和试验基础 .

阻振质量对板平面弯曲波传播的阻抑(英文)

研究了无限板上受点激励时阻振质量对结构声传递的阻抑, 采用基于能量观点的隔振度来定义阻振质量的阻抑作用。通过理论分析验证了隔振度简化公式的可行性。发现板平面弯曲波分别和阻振质量的弯曲波和扭转波达到最佳耦合时, 平面弯曲波发生最大透射。算例分析和试验研究论证了理论分析的正确性, 为阻振质量应用于结构声传递途径的控制提供了理论和试验基础。

航空大锻件煤气加热炉控温及防振系统设计

研究了供航空大锻件加热用煤气炉控温系统的结构。该控温系统，通过ＳＴＤ总线工业控制机，实现了炉温、流量、压力的综合控制，及煤气流量与空气流量间的比例控制。还设计了自动、手动等多种控温方式，及独立的记录、超温报警等系统。另外，还对变送器、计算机。

多点同时空间激光通信系统高效偏振分光技术研究

在多点同时空间激光通信系统中,为实现多信号光束的高效隔离,对系统中的收发分光分系统进行了研究与设计,采用了并不常用的偏振分光方式可有效减少系统波长数量。通过实验发现使用普通偏振分光棱镜的系统隔离度较低,约为-57.27d B,为此对普通棱镜进行了改进,将其非工作面削成斜角,使杂散光偏出接收探测器视场,得到异形分光棱镜,通过实验验证偏振隔离度为-64.1d B,有了一定的提高。

Research progresses of artificial intelligence in MRI of lumbar degenerative diseases

The incidence of lumbar degenerative diseases is increasing year by year,and MRI is often used in clinical diagnosis.In recent years,artificial intelligence(AI)has rapidly developed in medical field and can be used for image segmentation and auxiliary diagnosis of lumbar degenerative diseases.The research progresses of AI in MRI of lumbar degenerative diseases were reviewed in this article.

大米真空包装件在流通过程中抵抗外力能力的研究

真空包装是大米销售包装常用的一种保鲜技术。为减少真空包装大米在流通过程中的破袋问题,就不同真空度对大米包装件在流通过程中抵抗外力能力进行深入的研究,以解决大米真空包装流通过程中的破袋问题。

Theoretical and Experimental Research of High-Static-Low Dynamic Torsional Vibration Isolator for Ship Shafting

High-static-low-dynamic stiffness (HSLDS) vibration isolators have been demonstrated to be an effective means of attenuating low-frequency vibrations, and may be utilized for ship shafting applications to mitigate torsional vibration. This paper presents the construction of a highly compact HSLDS torsional vibration isolator by connecting positive and negative stiffness components in paral lel. Based on mechanical model analysis, the restoring torque of negative stiffness components is de rived from their springs and connecting rods, while that of positive stiffness components is obtained through their circular section flexible rods. The quasizero stiffness characteristics of the HSLDS iso lator are achieved through a combination of static structural simulation and experimental test. The tor sional vibration isolation performance is assessed by means of numerical simulation and theory analy sis. Finally, the frequency-sweep vibration test is conducted. The test results indicate that the HSLDS torsional vibration isolator exhibits superior low-frequency isolation performance compared to its linear counterpart, rendering it a promising solution for mitigating low-frequency torsional vi bration in ship shafting.

Multi-dimension and multi-modal rolling mill vibration prediction model based on multi-level network fusion

Mill vibration is a common problem in rolling production,which directly affects the thickness accuracy of the strip and may even lead to strip fracture accidents in serious cases.The existing vibration prediction models do not consider the features contained in the data,resulting in limited improvement of model accuracy.To address these challenges,this paper proposes a multi-dimensional multi-modal cold rolling vibration time series prediction model(MDMMVPM)based on the deep fusion of multi-level networks.In the model,the long-term and short-term modal features of multi-dimensional data are considered,and the appropriate prediction algorithms are selected for different data features.Based on the established prediction model,the effects of tension and rolling force on mill vibration are analyzed.Taking the 5th stand of a cold mill in a steel mill as the research object,the innovative model is applied to predict the mill vibration for the first time.The experimental results show that the correlation coefficient(R^(2))of the model proposed in this paper is 92.5%,and the root-mean-square error(RMSE)is 0.0011,which significantly improves the modeling accuracy compared with the existing models.The proposed model is also suitable for the hot rolling process,which provides a new method for the prediction of strip rolling vibration.

Design and implementation of digital closed-loop drive control system of a MEMS gyroscope

In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system （MEMS） gyroscope are analyzed in principle. A novel drive circuit for the MEMS gyroscope in digital closed-loop control is proposed, which utilizes a digital phase-locked loop （PLL） in frequency control and an automatic gain control （AGC） method in amplitude control. A digital processing circuit with a field programmable gate array （FPGA） is designed and the experiments are carried out. The results indicate that when the temperature changes, the drive frequency can automatically track the resonant frequency of gyroscope in drive mode and that of the oscillating amplitude holds at a set value. And at room temperature, the relative deviation of the drive frequency is 0.624 ×10^-6 and the oscillating amplitude is 8.0 ×10^-6, which are 0. 094% and 18. 39% of the analog control program, respectively. Therefore, the control solution of the digital PLL in frequency and the AGC in amplitude is feasible.

提取脉冲响应函数的小波变换法及时域法分析

针对有关文献提出的利用小波变换来求取结构系统脉冲响应函数的方法,指出利用小波变换的方法与传统的基于Duharmal积分的时域法具有一致性,并且时域法具有更高的效率。文中简要地介绍了这两种方法的原理,并且在小波分解层数的意义上从多层分解到一层分解以及到时域法,详细分析了利用小波分解的实质,指出时域法是小波分解方法在层数上的延伸,因此是效率最高的。用矩阵广义逆的方法克服了时域法在对输入信号采样时存在的问题。用四自由度的弹簧-质量-阻尼系统进行了仿真,并且在悬臂梁上进行了实验,结果都表明本文得出的结论是正确的。

Vibration control of pedestrian-bridge vertical dynamic coupling interaction based on biodynamic model

The human-induced vertical vibration serviceability of low-frequency and lightweight footbridges is studied based on the moving mass-spring-damper（MMSD） biodynamic model, and the mass damper（TMD） with different optimal model parameters being used to control the vertical vibration.First, the MMSD biodynamic model is employed to simulate the pedestrians, and the time-varying control equations of the vertical dynamic coupling system of the pedestrian-bridgeTMD are established with the consideration of pedestrianbridge dynamic interaction; and the equations are solved by using the Runge-Kutta-Felhberg integral method with variable step size. Secondly, the footbridge dynamic response is calculated under the model of pedestrian-structure dynamic interaction and the model of moving load when the pedestrian pace frequency is consistent with the natural frequency of footbridge. Finally, a comparative study and analysis are made on the control effects of the vertical dynamic coupling system in different optimal models of the TMD. The calculation results show that the pedestrian-bridge dynamic interaction cannot be ignored when the vertical human-induced vibration serviceability of low-frequency and light-weight footbridge is evaluated. The TMD can effectively reduce the vibration under the resonance of pedestrian-bridge, and TMD parameters are recommended for the determination by the Warburton optimization model.

Bulk-Silicon Resonant Accelerometer

Resonant accelerometer is designed,which includes two double-ended tuning forks,a proof mass,four-leverage system amplifying inertial force,and drive/sense combs.Each tuning fork is electrostatically actuated and sensed at resonance using comb electrodes.The device is fabricated using MEMS bulk-silicon technology,whose sensitive degree is 27 3Hz/g,and the resolution is 167 8μg.

Deposition of High Quality GaN Film Under High ECR Plasma Density

Aim To investigate the influence of ion density( n i) on the deposition of wurtzite GaN films on the substrate of α Al 2O 3(0001) by electron cyclotron resonance plasma. Methods Langmuir probe measurement, Double crystal X ray diffraction and Hall measurement were used. Results The quality of GaN film strongly depended on its growth condition. The higher ion density resulted in a higher amount ratio of N/Ga and a lower background electron concentration of GaN film. When the GaN was prepared in the ion density of 2 0×10 11 cm -3 , the amount ratio of N/Ga was close to 1, the electron background density was 3 7×10 18 cm -3 and its full width at half magnitude(FWHM) was 16?arcmin. Conclusion The quality of GaN film can be improved by raising the plasma density.

Thermostability of Vane Absorber

Aim To improve the thermostability of vane absorbers while designing and manu- facturing. Methods Having considered the structural features of vane absorbers, measures that could reduce the force decay ratio of vane absorbers were discussed. A kind of practical auto temperature compensation apparatus, whose theoretical basis had been discussed, was designed. Results Compared to the prototype vane absorber, this kind of apparatus could decrease force decay ratio sharply. Thus, the thermostability of vane absorbers was improved greatly The accuracy of theoretical analysis and the effectiveness and feasibility of the apparatus was proved by actual testing Conclusion changing vane absorber's configuration, its performance is improved.