Key Engineering Materials Vol. 667

Abstract: In order to detect the electrothermal heating tube internal electrothermal film resistance and the relationship between the two electrode gap, this thesis used design using a testing equipment: The two ends of the measurement period from two electrodes, and the probe spacing can be adjusted ; The two measuring points into hair heat pipe internal contact with the resistive film, using the bleeder circuit, the indirect measuring resistance membrane resistance and the relationship between the two measuring points spacing; then analyze the measurement data, the relationship between the two electrode gap and electrothermal film resistance. The use of such equipment, the measured data, we can analyze the electrothermal film heating pipe internal heating membrane resistance and two measurement of the end head distance is linear change. The linear relationship between the use of electrothermal film heating tube internal electrothermal membrane resistance, can estimate the range of internal electric heating film heating pipe resistance from two the distance between the electrodes, get the change range of heating tube power.

Abstract: In order to study magneto rheological fluid shear characteristics developing of magnetic field and temperature field under the actual condition (non-uniform composite field), Experimental device that test magneto rheological fluid (MRF) Shear yield stress under Non uniform composite field was developed. The device of the magnetic field distribution, temperature conductivity, shear yield stress are studied in theory and prototype production, and then testing the Shear yield stress of magneto rheological fluids of different magnetic field, temperature yield . The adjusting range of temperature of the experimental device is for 0-200, the magnetic field adjusting range by adjusting the current of the electromagnetic coil in the 0mt-300mt. Makes the air gap magnetic field intensity is 20mt, magneto rheological fluid in the shear rate at , the research of magneto rheological fluid shear yield stress with the magnetic field variation different temperatures (T=10, T=50, T=100,T=130, T=150, T=170) . The experimental results show that: in the 10-170, the temperature value basically does not affect the shear yield stress of the MR fluid, but the temperature is less than 10 and the temperature is greater than 170, the effects that temperature size on MRF Shear yield stress is relatively large.

Abstract: In order to detect weak chemiluminescence signal rapidly and high accurately, a chemiluminescence detection system is designed based on the core chip FPGA. The system uses a static injection mechanism as chemiluminescence reaction conduit. High-performance photodiode converts chemiluminescence signals into electrical signals replacing the traditional photomultiplier tube. It can meet the test requirements while reducing the cost of the detection system. The signal processing and storage system FPGA-based consists of A/D converter module, serial communication module, the keyboard scan control modules and memory modules. Nitrite ions in water samples are detected and the results show that in a certain concentration range the calibration curve of NO_2- concentration and luminescence intensity is linear, the linear regression equation is Y = 0.4148X + 2.6508, and the correlation coefficient is R² = 0.9832. The relative standard deviation values are 2.7%(n=11).

Abstract: Asphalt concrete is a typical road building material of advanced asphalt pavements. Under the reciprocating vehicle loading, fatigue cracks are reduced inevitably, which seriously affect road performance. Therefore, effective detection and diagnosis of fatigue crack propagation has become a hot research issue. Acoustic emission detection test is a new dynamic nondestructive testing technology which has some features of real-time, online and overall detection. The main purpose of this paper systematically analyses the development process of acoustic emission technology applied in health monitoring field of asphalt concrete pavement structure, and to state the acoustic emission source localization principle, the parameters of acoustic emission signal analysis method, the acoustic emission signal waveform analysis method, etc. Furthermore, from the aspects of the asphalt concrete fatigue performance, crack evolution process and positioning technology, this paper fundamentally discuss the future technological development prospect of acoustic emission technology which is applied in the field of monitoring and diagnosis of asphalt concrete pavement structure, and provide a new perspective for the whole dynamic maintenance of road , and the information implementation of pavement maintenance strategies at later stage.

Abstract: this paper introduced two parameters, step height and end face Angle by improving the structure of the prestressed combination concave die to improve mould work performance, Analyzed the step height of 0-10mm, end face Angle of 0-35^o, the change of stress, with the help of MATLAB software fitting the equivalent stress and the function relation between the step height and transverse Angle. Using stepwise slanting end face combination concave die can improve the bearing capacity and reduce the fracture and deformation of the die.

Abstract: According to the real structure and work condition of a high-flow mixed gas control valve used in recycling generating electricity project, a modal analysis model based on fluid-structure coupling system of control valve is set up. The natural frequency and mode of valve plug and stem is obtained. The structure damage diagnostic method of high-flow valve stem is put forward. According to the change of natural frequency of the valve stem to judge appearance of fracture cracks is explored. According to the amount by which the variation of natural frequency to determine the size of crack is discussed. It is the preliminary diagnosis to the damage of a high-Flow control valve stem in the special working environment, to avoid the gas leaks, the failure of valve action, adjust or commutation, etc.

Abstract: This thesis uses a kind of detection method: The two ends of the measurement period from two electrodes, and the probe spacing can be adjusted. Two measuring end head into the interior with electric heat pipe membrane contact ,used the voltage dividing circuit,relations indirect detection of electric resistance film ends with the two measuring pitch. Then the measured data analysis, obtains the relationship between the two electrode spacing and the electrothermal membrane resistance. Make this thought method may not be used to measure the electric heating film resistance, become a simple and practical method for measuring the electric heating film resistance. Using this method, the measured data can be analyzed, indirectly electrothermal film heating pipe internal resistance value and the two measurement of the end head distance is linear change. The linear relationship between the use of electrothermal film heating tube internal electric heating film resistance, the resistance can be estimated from the distance between the two electrodes, get the change range of heating tube power.

Abstract: The electro-hydraulic servo valve is the essential component of the electro-hydraulic servo control, and it was mainly used on many fields such as aviation, aerospace and navigation etc.People use the electro-hydraulic servo valve to drive plenty of loads. The electro-hydraulic servo valve has many advantages such as fast dynamic response, high control precision, and longevity. Hence, for the elastic element of the electro-hydraulic, which works as the significant feed-back component the characteristic of the stiffness has played an essential role in the electro-hydraulic servo. Based on the previous research of the technology automation and inspection experiment, this paper proposes an auto-stiffness admeasuring apparatus for the elastic element of the Hydraulic servo. and the experiment research has been proceeded. The experimental result shows that, the auto-stiffness admeasuring apparatus has the advantages of high precision, high automation; it can be well used in the productive practice.

Abstract: HLP type hydraulic oil has wide application in aerospace field. The existing measurement method of Laval nozzle throat diameter efficiency is low, and has the potential to cut parts surface. Therefore, a non-contact throat diameter measuring method based on the hydraulic oil is proposed. Then the flow field is simulated, and measurement parameters are calculated. The flow field analysis results show that this method is suitable for measuring Laval nozzle throat diameter.

Abstract: Research on biomechanical properties of skin and its detection method is significant in learning about and mastering the physiological function of the skin, assessing the degree of skin aging correctly as well as doing some appropriate care. As one of the important indexes for skin mechanics, viscoelastic can reflect the state of skin system timely, and play a guiding role in the treatment of diseases related. Meanwhile, surgery recuperation and cosmetics can be effectively measured and quantified. Due to the uniqueness and complexity of the structure of skin, the test method for its viscoelasticity is more complex than engineering meterial. In recent years, detection technology of skin viscoelastic has been paid great attention, especially to the non-invasive methods of skin viscoelastic. In this paper, the principle of non-invasive detection methods and their recent development are described, and the various detection methods and the major equipments are also analyzed.