石英谐振力传感器的温度自测及温度补偿

石英谐振器的基频和 3次泛音频率都是力和温度的函数 ,利用二者各阶温度系数除一阶外均相同的特性 ,基频的 3倍频与 3次泛音的差频是温度的线性函数并且与力无关 ,因此测量差频可以实现力传感器的温度自测和温度补偿。与采用分立的温度传感器相比 ,该方法消除了由于温度传感器和谐振器热惯性和空间位置不同引起的测温误差 ,提高了动态温度过程中的补偿精度。

差动石英谐振式力传感器的温度特性及其温度自测

推导出了差动石英谐振式力传感器的一种输出表达式,考虑温度的影响进一步得到了温度影响下的传感器输出特性。并找到了一种新的温度自测方法———差动式温度自测法。结果表明:选择较高的泛音次数、合适的作用力方位,能够提高传感器的测力灵敏度,可使其达到单敏感型传感器的4 1倍;温度是影响传感器输出特性的一个主要因素,温度越高,影响越大,必须对输出特性进行补偿。选择合适的泛音次数、作用力方位能提高温度自测的灵敏度,可使其达到双频温度自测的2 7倍。

涂层刀具切削温度自测传感器

针对涂层刀具切削加工,研制出一种利用涂层刀具本身作为切削温度传感器的涂层刀具切削温度自测传感器。该传感器利用刀具的涂层和基体作为热电偶,基本上不影响刀具热量的传递。为了准确地标定该传感器,制作了专门的标定装置。对传感器的工作原理进行了分析,特别指出该传感器的两个引出导线应采用不同材料的导线。运用开发的涂层刀具温度自测传感器进行了切削试验,结果表明,这种新型的传感器能够用来实时测量刀具前刀面测试点的温度。温度自测传感器的研制为涂层刀具切削温度的实时测量提供了测试方法。

Sea water temperature auto-monitoring system based on general packet radio service (GPRS)

This paper introduces the design and implementation of sea-water temperature auto-monitoring system based on General Packet Radio Service （GPRS）. This system integrates modern wireless communication technology, the signal gathering technology and computer network technology. MSC1210 microcontroller is used in data collection device in order to make system accurate and fast. In addition, wireless and Internet technologies are used for transferring and displaying collected field data. A prototype system has been completed and tested in field trials. The results proved the feasibility and usefulness of this system for monitoring the temperature. By using this system, a lot of resources and money can be saved.

Magnetic field properties caused by stress concentration

Measurements of the effects of tensile stress on magnetic field properties, infrared thermography and (acoustic) emission of a cuboid sample with an elliptical hole in its center were presented. The tensile stress was applied perpendicularly to the sample by electro-tension machine according to a step-loading curve. The changes of the sample temperature was recorded by an infrared thermography system and the noise of domain reversal was inspected by two acoustic probes, which were placed on each end of the sample near the collets of the electro-tension machine, when the sample was in loading process. The magnetic fields on the surface of the sample were inspected with 8 mm lift-off when the loads were held. Valuable information about the changes of domains was obtained from analysis of acoustic emission signals in loading process. Infrared images of the sample provided complementary information about the state of the sample. The results show that stress concentration in ferromagnetic material affects the direction and structure of domain and generates net magnetic moment on its surface. The distribution and magnitude of the net magnetic moment are correlative with those of stress.

Design of Environmental Monitoring and Control System for Large-scale Pig House with Fermentation Bed

The design and assembly of environmental monitoring and control system for large-scale pig house with fermentation bed helped to solve the problem of environmental automatic control in piggery.The sensors would monitor the temperature,humidity,light,wind direction,wind speed,CO2,NH3and other parameters.On-line real-time data collection was achieved.The expert system was constructed to control the temperature in piggery below 30℃,to control the air and mattress humidities higher than 65%.Under the conditions of different season or different wind speed,even in day and night,the control actuators were different.The actuators included fanning wet curtain,lighting,micro spraying,spraying,propeller fan,electric aluminum alloy shutter and spraying systems on the roof.The actuators were integrated,and they control the piggery environment simultaneously.The system also designed the remote video monitor interface,parameter-monitoring curved interface and operation interface,which provided a good man-machine interface.

Real-Time Monitoring and Flagging of Extreme Value Forecasts A Practical Example and Interesting Findings

Forecasts of record values are usually avoided unless expected to occur with great confidence within less than 48 hours, or in association with an extreme event such as a hurricane. Otherwise the risk of a high visibility false alarm outweighs the benefit of a correct early hit. Yet automated forecasts may occasionally include record values beyond day 2, which forecasters may choose to downplay, or not. In Canada, forecasters keep their focus on high impact weather for days l and 2, so that forecasts for day 3 and beyond are mostly automated and usually released after a quick glance. So a process was designed to bring up cases where automated temperature forecasts exceed known records for a number of sites, with the sole purpose of alerting the forecasters who may decide whether or not modifications are needed before release. As a by-product it is found that some record temperature forecasts are issued every day in Canada, even more records are actually observed, and in recent years there have been twice as many new high records as low ones. We discuss the origin of the process, its logics, its current status, interesting findings, and possible improvements.

Experiment study of optimization on prediction index gases of coal spontaneous combustion

The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as "K". The ratio of each index gas and value of "K", and the ratio of combination index gases and value of "K", were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C_2H_4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C_2H_6)/Φ(C_2H_2) and Φ(C_2H_6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.

Methods of data processing in multi-wavelength thermometry

Three kinds of methods for processing the data of the multi-wavelength pyrometer are presented in this paper and are named curve auto-search method, curve auto-regression method and neural network method. Tbe experimental results indicate that the calculated temperature and the spectral emissivity compared with the true target temperature and spectral emissivity have significant deviation using the curve auto-search and the curve auto-regression methods. However, the calculated temperature and the spectral emissivity with higher accuracy can be obtained using the neural network method.

The effect of the boron-ions implantation on the performance of RADFETs

In this work, we studied on the boron-ions implantation, including the implant dose and post-annealing temperature on the performance of PMOS radiation field-effect transistors(RADFETs) in experimental. The possible traps and defects induced by ions implantation in the gate-oxide and their further impacting on the sensitivity and dose range of RADFETs were analyzed qualitatively. Our devices had the dry/wet/dry sandwich gate-oxide of 420 nm thick. Different ion-implanting doses and post-annealing temperatures were carried out during the RADFETs fabrication. We built a real time auto-measurement system to realize the auto-state-switch between irradiation and read-out modes, and in-situ measurement of output voltage for ten devices in turn at once of radiation experiment. The threshold voltage, dose range and sensitivity of RADFETs were extracted and analyzed in detail. The results showed that the highest sensitivity of 229 mV/Gy achieved when the implant dose was2.2×1011 cm.2 and the post-annealing temperature was 1000°C, and the dose range of 34 Gy as well.

Design and simulation of self-powered radio frequency identification (RFID) tags for mobile temperature monitoring

This paper presents a design for a self-powered radio frequency identification (RFID) tag with a thin film bulk acoustic reso- nating piezoelectric power supply (PPS), which can be used for portable remote temperature monitoring. We call this system a PPS-RFID for short. The RFID systems have been found to have many applications in the internet of things (IOT) in the past decade. But semi-active RFID tags require an onboard battery which limits their applications in many fields. For these reasons, our research focuses on power sources for the RFID tags. This paper emphasizes the circuit design and simulation of PPS. In our tests, 0.283 mW was generated by PPS at 1 Hz vibration by a 650 N impact force. The results showed that the integrated PPS could supply sufficient power for the designed PPS-RFID tag. The PPS-RFID tag can be widely used for temperature monitoring during mobile transport of perishable items such as medicines or food.

Charge density wave transition in Na_2Ti_2Sb_2O probed by^(23)Na NMR

Herein we investigated the electronic properties of layered transition-metal oxides NazTi2Sb2O by 23Na nuclear magnetic reso- nance （NMR） measurement. The resistivity, susceptibility and specific heat measurements show a phase transition at approxi- mately 114 K （TA）. No splitting or broadening in the central line of 23Na NMR spectra is observed below and above the transi- tion temperature indicating no internal field being detected. The spin-lattice relaxation rate divided by T （I/T1T） shows a sharp drop at about 110 K which suggests a gap opening behavior. Below the phase transition temperature zone, I/T1T shows Fermi liquid behavior but with much smaller value indicating the loss of large part of electronic density of states （DOS） because of the gap. No signature of the enhancement of spin fluctuations or magnetic order is found with the decreasing temperature. These results suggest a commensurate charge-density-wave （CDW） phase transition occurring.