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悬浮式磁流体惯性传感粘阻可控机理分析
磁流体 惯性传感 粘阻尼
2014/2/28
实现悬浮式磁流体惯性传感的量程控制关键在于分析基于经典粘性流体力学理论的动态粘度特性和流固系统运动特性。在质量块作简谐运动下，建立惯性传感结构中间隙的流动模型并对理论方程进行求解。在不同动力粘度下，对作简谐运动的传感运动块进行流阻力进行数值计算，结果表明：质量块所受粘阻力主要是两侧压力差，压力差随时间呈现简谐特性，幅值与磁流体动力粘度有较好的线性关系；在选定实验参数后研究结果为压差相位超前22°～...
模态节点对用小波系数检测拱损伤的影响
模态节点 损伤检测 拱模态 小波分析
2014/2/28
数值模拟了不同损伤位置时拱的前2阶径向位移模态。结合小波变换理论对振型进行分析，对比了1、2模态在不同损伤位置时的小波系数，并讨论了小波变化尺度对损伤处小波系数的影响。结果表明：小波系数的突变点反映了结构的损伤位置，损伤位置远离模态节点时小波系数较大，由于各阶模态节点对应的位置不同，可通过多个模态的小波系数来综合判定损伤。
介绍了波纹壳的研究进展,重点综述了波纹膜片非线性弯曲、振动和稳定性研究方法及方法比较。最后提出了波纹壳非线性力学研究中值得关注的几个重点研究方向。
为提高大尺寸箭弹质量特性的测量精度，对产品测量位姿的标定方法进行了研究。建立测量设备运动学模型，在模型基础上分析了测量位姿误差对测量结果的影响。阐述了基于运动学原理的标定方法和标定步骤，并对标定模型中参数进行分析和分类，将神经网络与运动学相结合进行位姿的标定。实验结果表明，采用运动学方法标定位姿后将质心测量误差减小到原来的10%，转动惯量和惯性积测量误差减小到原来的90%和23%；而采用神经网络与...
在光束整形衍射光学元件的设计中，为提高目标衍射图样的重构精度，提出了一种基于相位混合的迭代算法。该算法采用复振幅每次迭代循环的初始相位与返回相位的加权和为驱动函数，并以每次循环开始和结束时的光强比较作为光束相位变换的判据。简单讨论了Gerchberg-Saxton（GS）算法的缺陷，并以高斯分布-均匀分布和高斯分布-环分布为例，对比了改进算法与GS算法的设计结果。计算机仿真结果表明，改进算法的极限...
Ad-hoc网络的负载自适应MAC协议
MAC协议 负载因子 CSMA/CA机制 Token-Ring机制 接入延时
2014/6/9
基于Ad-hoc网络，提出一种负载自适应MAC协议——LAP。该协议综合考虑了站点个数、帧长度和帧到达率对网络负载的影响，并引入负载因子评估当前网络的负载状况。当负载因子小于切换阈值时，LAP采用基于竞争的CSMA/CA机制；反之，则采用基于非竞争的Token/Ring机制。仿真证明，该协议能在重负载和轻负载环境中有效控制接入延时，最终提高网络实时性。
Axisymmetric Grazing-Incidence Focusing Optics for Small-Angle Neutron Scattering
Atom and neutron optics X-ray optics small-angle neutron scattering
2012/5/17
We propose and design novel axisymmetric focusing mirrors, known as Wolter optics, for small-angle neutron scattering instruments. Ray-tracing simulations show that using the mirrors can result in mor...
硅微陀螺仪闭环正交校正研究
硅微陀螺仪 正交误差 校正电极 闭环控制
2014/4/22
针对硅微陀螺仪中正交误差的来源进行了分析，设计了一种基于正交校正电极的闭环控制回路。该电路通过正交校正电极产生静电耦合刚度，以此来抵消结构耦合刚度，从而抑制正交误差。给出了设计方案的原理框图，利用simulink对整个控制回路进行仿真，仿真结果表明该方案能够较好地抑制正交误差。对加入正交校正前后的硅微陀螺仪样机进行了测试，实验结果表明加入闭环正交校正后，陀螺仪样机的正交误差信号减小了约一个量级。
SPHERES, Julich's High-Flux Neutron Backscattering Spectrometer at FRM II
SPHERES Julich's High-Flux Neutron FRM II Instrumentation and Detectors
2012/4/24
SPHERES (SPectrometer with High Energy RESolution) is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Juelich Centre for N...
From x-ray telescopes to neutron scattering: using axisymmetric mirrors to focus a neutron beam
atom and neutron optics x-ray optics Instrumentation and Detectors
2012/4/24
We demonstrate neutron beam focusing by axisymmetric mirror systems based on a pair of mirrors consisting of a confocal ellipsoid and hyperboloid. Such a system, known as a Wolter mirror configuration...
Critical components in 0.14 THz communication systems
Critical components 0.14 THz communication systems Instrumentation and Detectors
2012/4/24
In the super-heterodyne terahertz communication system, the proper design of the critical components like mixers and filters are of great importance for enhancing its performance. In this work, some i...
The 10 Tesla muSR instrument: detector solutions
muon-spin rotation muonium scintillation detector time resolution Geiger-mode Avalanche Photodiode
2012/4/24
Solutions to the detector system of the High-Field muSR instrument at the Paul Scherrer Institut (PSI) in Switzerland are presented. The strict technical requirements are fulfilled through the applica...
Wide-band current preamplifier for conductance measurements with large input capacitance
Wide-band current preamplifier conductance measurements large input capacitance
2012/4/20
A wide-band current preamplifier based on a composite operational amplifier is proposed. It has been shown that the bandwidth of the preamplifier can be significantly increased by enhancing the effect...
The Jefferson Lab Frozen Spin Target
frozen-spin target polarized target dilution refrigerator internal holding coil
2012/4/19
A frozen spin polarized target, constructed at Jefferson Lab for use inside a large acceptance spectrometer, is described. The target has been utilized for photoproduction measurements with polarized ...
Energy Loss Signals in the ALICE TRD
Ionization energy loss dE/dx Transition radiation TR Cosmic muon
2012/4/19
We present the energy loss measurements with the ALICE TRD in the $\beta\gamma$ range 1--10$^{4}$, where $\beta=v/c$ and $\gamma=1/\sqrt{1-\beta^2}$. The measurements are conducted in three different ...