随着国家对核电站安全运行的要求越来越高,为了在事前诊断出核电站的运行故障,及早采取相应的处理手段,并将安全事故的损害和经济损失降至最低,本研究提出核电站一回路的松动部件故障诊断在线监测问题。文中介绍一种核电站松动部件监测...随着国家对核电站安全运行的要求越来越高,为了在事前诊断出核电站的运行故障,及早采取相应的处理手段,并将安全事故的损害和经济损失降至最低,本研究提出核电站一回路的松动部件故障诊断在线监测问题。文中介绍一种核电站松动部件监测系统(Loose Parts Monitoring System,LPMS)和基于此系统应用的加速度传感器。详述松动部件产生的原因、监测系统的工作原理、系统功能、基于此应用而设计的加速度传感器的性能以及系统中测试区域和加速度计布置位置,并通过某大型回路试验,验证了该松动部件监测系统的功能和应用于此系统的加速度传感器的性能指标。展开更多
This paper presents two approaches for system-level simulation of force-balance accelerometers. The derivation of the system-level model is elaborated and simulation results are obtained from the implementation of tho...This paper presents two approaches for system-level simulation of force-balance accelerometers. The derivation of the system-level model is elaborated and simulation results are obtained from the implementation of those strategies on the fabricated silicon force-balance MEMS accelerometer. The mathematical model presented is implemented in VHDL- AMS and SIMULINK TM,respectively. The simulation results from the two approaches are compared and show a slight difference. Using VHDL-AMS is flexible,reusable,and more accurate. But there is not a mature solver developed for the language and this approach takes more time, while the simulation model can be easily built and quickly evaluated using SIMULINK.展开更多
A tunneling accelerometer is fabricated and characterized based on the extension of the silicon-glass anodic-bonding and deep etching releasing process provided by Peking University.The tunneling current under open lo...A tunneling accelerometer is fabricated and characterized based on the extension of the silicon-glass anodic-bonding and deep etching releasing process provided by Peking University.The tunneling current under open loop operation is tested in the air by HP4145B semiconductor analyzer,which verifies the presence of tunneling current and the exponential relationship between tunneling gap and tunneling current.The tunneling barrier is extrapolated to be from 1.182 to 2.177eV.The threshold voltages are tested to be 14～16V for most of the devices.The threshold voltages under -1,0,and +1g are tested,respectively,which shows the sensitivity of the accelerometer is about 87mV/g.展开更多
Based on the theory of elastic mechanics and material mechanics, the orientation precision of the hohl schaft kegel（HSK） tooling system in static and dynamic states is theoretically and experimentally studied. The r...Based on the theory of elastic mechanics and material mechanics, the orientation precision of the hohl schaft kegel（HSK） tooling system in static and dynamic states is theoretically and experimentally studied. The relation between the clamping force and the shank taper is obtained. And a proper clamping force is found to be essential to assure the axial and radial orientation precisions of the HSK tooling system in high speed machining （HSM）. Analytical results show that the reason why the HSK tooling system can keep high precision at the high rotational speed is that the actual axial clamping force keeps the two surfaces of the shank and the spindle in contact all the time.展开更多
Aim Using animals as object of experiment to acquire various patterns of low cerebral blood pressure and reduced blood capacity in cerebral tissues of astronauts due to the load of acceleration. Methods The isotope ...Aim Using animals as object of experiment to acquire various patterns of low cerebral blood pressure and reduced blood capacity in cerebral tissues of astronauts due to the load of acceleration. Methods The isotope tracking technique was applied to mark the blood and record the dynamic curves of cerebral blood flow changes under various accelerations, and the relevant mathematical model was set up using the method of system recognition. Also the method of factor analyzing was used to select two out of the data collected by eight sensors as two factors. Results One of the two factors reflects the various patterns in the astronaut's upper body, the other for the lower body. Parameters of rise time, delay time and steady value reflect the results under different acceleration. Conclusion Whether for the upper body or the lower body, blood flow changes can be considered as a second order system model. This method provides a new technique and method of doing research on astronaut's endurance of acceleration and selecting astronauts.展开更多
文摘介绍了一种基于CPLD内置UFM(user flash memory)的嵌入式加速度数据采集系统,并给出了各个功能模块的实现方法。整个采集系统主要包括电荷放大器模块、信号调理模块、A/D转换模块、CPLD控制模块和电源模块。整个系统以EPM570T100C5为核心,由该CPLD控制A/D芯片MAX1311进行模数转换并根据相应的时序操作把转换到的数据存储到内置的UFM里。在设计电路板时,采用MAX II CPLD来合并逻辑和存储器(UFM),从而缩短了芯片至芯片延时,减小了电路板面积,降低了系统总成本。该系统可以稳定实现300k的采样速率,可以嵌入到设备内部进行加速度以及各种冲击信号的检测。
文摘随着国家对核电站安全运行的要求越来越高,为了在事前诊断出核电站的运行故障,及早采取相应的处理手段,并将安全事故的损害和经济损失降至最低,本研究提出核电站一回路的松动部件故障诊断在线监测问题。文中介绍一种核电站松动部件监测系统(Loose Parts Monitoring System,LPMS)和基于此系统应用的加速度传感器。详述松动部件产生的原因、监测系统的工作原理、系统功能、基于此应用而设计的加速度传感器的性能以及系统中测试区域和加速度计布置位置,并通过某大型回路试验,验证了该松动部件监测系统的功能和应用于此系统的加速度传感器的性能指标。
文摘This paper presents two approaches for system-level simulation of force-balance accelerometers. The derivation of the system-level model is elaborated and simulation results are obtained from the implementation of those strategies on the fabricated silicon force-balance MEMS accelerometer. The mathematical model presented is implemented in VHDL- AMS and SIMULINK TM,respectively. The simulation results from the two approaches are compared and show a slight difference. Using VHDL-AMS is flexible,reusable,and more accurate. But there is not a mature solver developed for the language and this approach takes more time, while the simulation model can be easily built and quickly evaluated using SIMULINK.
文摘A tunneling accelerometer is fabricated and characterized based on the extension of the silicon-glass anodic-bonding and deep etching releasing process provided by Peking University.The tunneling current under open loop operation is tested in the air by HP4145B semiconductor analyzer,which verifies the presence of tunneling current and the exponential relationship between tunneling gap and tunneling current.The tunneling barrier is extrapolated to be from 1.182 to 2.177eV.The threshold voltages are tested to be 14～16V for most of the devices.The threshold voltages under -1,0,and +1g are tested,respectively,which shows the sensitivity of the accelerometer is about 87mV/g.
文摘Based on the theory of elastic mechanics and material mechanics, the orientation precision of the hohl schaft kegel（HSK） tooling system in static and dynamic states is theoretically and experimentally studied. The relation between the clamping force and the shank taper is obtained. And a proper clamping force is found to be essential to assure the axial and radial orientation precisions of the HSK tooling system in high speed machining （HSM）. Analytical results show that the reason why the HSK tooling system can keep high precision at the high rotational speed is that the actual axial clamping force keeps the two surfaces of the shank and the spindle in contact all the time.
文摘Aim Using animals as object of experiment to acquire various patterns of low cerebral blood pressure and reduced blood capacity in cerebral tissues of astronauts due to the load of acceleration. Methods The isotope tracking technique was applied to mark the blood and record the dynamic curves of cerebral blood flow changes under various accelerations, and the relevant mathematical model was set up using the method of system recognition. Also the method of factor analyzing was used to select two out of the data collected by eight sensors as two factors. Results One of the two factors reflects the various patterns in the astronaut's upper body, the other for the lower body. Parameters of rise time, delay time and steady value reflect the results under different acceleration. Conclusion Whether for the upper body or the lower body, blood flow changes can be considered as a second order system model. This method provides a new technique and method of doing research on astronaut's endurance of acceleration and selecting astronauts.
