Applied Mechanics and Materials Vols. 635-637

Abstract: In this paper, three wire structure of the airflow level posture sensor is described. Using ANSYS-FLOTRAN CFD program, the temperature field and the stream field in sensing element of three wire structure and two wire structure under the effect of the different tilt state, has been obtained by a series of procedure, such as model building, meshing, loads applying and equation solving. The results are as follow: In tilt status, the airflow rate difference of three wire structure is nearly five times bigger than two wire structure in the two heat sources. Three wire structure makes heating wire separated from detection wire, solves the contradiction between operating current and output sensitivity, and decrease operating current. The test results show: The compare between three wire structure of the airflow level posture sensor and two wire structure of the airflow level posture sensor is that the sensitivity increases from 10 mV /° to 18mV/°,response time decreases from 100mS to 40mS,operating current decreases from 80mA to 40mA, so three wire structure is better than two wire structure.

Abstract: Optical encoders have been used for decades as displacement measuring devices. As far as image measurement is concerned, CCD and CMOS are gradually used in metrology fields. In practice, performance of image ultraprecise optical encoders are related to environmental temperature, humidity, data processor speed, and vibration, thus measurement precision of encoders will be affected, and these factors limit their usage scale. Among these factors, the vibration is the largest effect factor. Here, a new experiment system was built to study vibration effect of measurement. Experiments indicated that the effects of vibration mainly exist in two aspects. Firstly, vibration induced deformation of glass grating, so distance of adjacent grating lines got uncertain. Secondly, random vibration affected CMOS image sharpness, and it reduced accuracy of encoding and decoding. Finally, some methods are provided to reduce the vibration of the grating encoder.

Abstract: Expound the importance of soil shear strength measurement at mudslide hidden point to release the loss caused by the disaster, explain the relationship between shear wave velocity, moisture content and shear strength, design the shear strength monitoring system combining the shear wave velocity measured by Piezoelectric bender elements and moisture content.

Abstract: Signal processing circuits are proposed for the electric field type time grating sensors. The proposed design scheme integrates sampling function and processing function into a signal field programmable gate array (FPGA) based on system on programmable chip (SOPC) technology. Employing NiosII technology and adding self-defined instructions improve data processing speed for time grating sensors. The proposed signal processing circuits are simple and stabile. The proposed signal processing circuits are applied to electric field type linear time grating sensors, the experiments results that the peak-to peak measuring error is 0.3um within 200mm without any corrections.

Abstract: In order to solve the problem of the complexity satellite temperature acquisition network cabling connectivity, diversity in temperature acquisition circuits, low temperature acquisition accuracy, complicated computation of temperature formula and so on. A single bus thermometry technology based on 1-wire commercial temperature measurement sensor DS18B20 instead of the conventional thermometry technology on the satellite was proposed. In the study, the space measurement system based on DS18B20 including the design of measurement temperature circuit, software and reliability was designed, and space environment adaptability experiment system was built to study on the temperature measurement performance and spatial adaptation of the commercial sensor DS18B20 in the space environment. The results show that commercial temperature measurement sensor DS18B20 is accurate in a vacuum environment at-50~100°C; the new temperature measurement circuit design makes the temperature collection network cabling easier, and makes solving formula simpler by directly reading the temperature value.

Abstract: As a result of the large-scale components' measuring environment complex, the workers measuring operation not reliably and so on factor influences, uses the non-contact electro-optic measuring technique is the main development direction of the large size components measuring. In this paper, iron tower component is taken as measuring object, online automatic detection is aimed to achieve, and the system frame is constructed to carry out electro-optic automatic detection of the iron tower component, then designing of large size examination machine will be accomplished.

Abstract: This study proposes a pre-stressed dual-layer six-axis force sensor with eight limbs, and discusses the structure analysis of the sensor. The number of measuring limbs is determined and the structure characteristics are introduced. Force distribution analysis of the sensor is presented based on the mathematical model and force mapping matrix. The forces on the measuring limbs are decomposed into particular solution and homogeneous solution. The results of the paper are useful for the development and further research of the pre-stressed six-axis force sensor.

Abstract: According to the industrial site of precision measurement and control systems, the demand for real-time monitoring and multi-task, the paper studied and designed an industrial site monitoring and control system based on Labview; overall structure of software and hardware, the system was designed system, the system platform-level and user-level using a two-stage multi-task scheduling strategy to achieve the industrial field parallel scheduling and control system to improve the operating efficiency of monitoring and control systems; practice shows that the system has high accuracy, strong and stable real-time, etc., to meet the monitoring needs of the industrial field, with a good prospect.

Abstract: The flow and temperature fields caused by point heat source were obtained with the method of FEA (finite element analysis), and the pendulum characteristic of nature convection gas in two-dimensional enclosure with small size was validated and explained. The results are as follow: (1) Whether in horizontal status or in tilting status, under the function of buoyancy lift, the direction of nature convection gas always keeps vertical upwards in two-dimensional enclosure, and it has the pendulum characteristic.(2)The temperatures of two points on the same isotherm are no longer equal. When the tilt angle is 10°, the temperature difference is 20K; when the tilt angle is 20°, the temperature difference is 40K.The tilt angle can be measured by using this characteristic of MEMS airflow level posture sensor.

Abstract: The main factors influencing the output wavelength of semiconductor are drift of working temperature and changes of working current. Therefore, the key technology of semiconductor frequency stabilization is to detect frequency shifts and convert the shifts into electrical signal, then feedback control the working current and the temperature in order to ensure that the output frequency basically remains unchanged. So, a laser wavelength measuring system based on DSP is designed in this paper. The measurement theory of the system and the design of hardware are given in this paper. The system is composed of DSP, optical grating, CCD and so on. This measurement method introduced in this paper makes the measurement intelligent and has high degree of accuracy of measurement.