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The main causes of pressure ulcer are the unrelieved contact stresses between the cushion and the human body and the deterioration of the skin condition caused by the impregnation of sweat and urine, especially the region around ischial tuberosities where the local pressure concentration appears. Pressure ulcer-preventing cushion that relieves the pressure concentration in a seated situation could help to decrease the incidence of pressure ulcer. A new concept of such cushion is to fill the cushion with small polyethylene elastic beads, which can redistribute the sitting pressure onto a larger supporting area and help to improve microcirculation. Then the local maximum sitting pressure falls and the skin will be maintained in fine condition. Both the human body buttock thigh modal and the cushion modal are built with ANSYS 14.5 to simulate the sitting condition and analyze the local maximum pressure with different diameters of the polyethylene beads and different filling ratios. The equivalent Young’s modulus of the cushion is analyzed using the homogenization method. With the local maximum pressure for index, the influence of diameters and filling ratios of the polyethylene beads on the pressure relief performance has been thoroughly investigated. Those results could give guidance on the design of cushions with proper material characteristic to lower the pressure ulcer prevalence rate.

A self-calibration method of coupling error is presented for 3-DOF displacement measurement of a planar moving stage based on two planar gratings. The self-calibration method using Fourier series is developed to extract the periodic systematic errors from the coupling errors. The extracted periodic systematic errors are compensated. Experiments are conducted to validate the validity of the self-calibration method and experimental results indicate that the coupling errors in x and y directions are reduced by 2 and 1.5 times respectively. It can be therefore concluded that the self-calibration method is suitable for the 3-DOF displacement measurement of a planar moving stage to improve the positioning accuracy.

At present, use of computer aided engineering (CAE) software is rapidly expanding in the manufacturing industry. However, the CAE software is not an easy tool to use because of its versatility and amount of expertise required to understand and evaluate simulation results. So the operation is more complex, and the error rate is higher in the engineering analysis. A CAE Intelligent Assisted Expert System (IAES) that supports Finite Element analysis was proposed and implemented. The CAE IAS is implemented based on VS2012 development environment, which is based on case and rule based reasoning. It is used to guide and assist CAE engineers to analyze the project, so that the accuracy and efficiency of the analysis are greatly improved and the product performance is better optimized.

The stability of the tunnel portal section under poor terrain and geological condition has always been the focus of construction safety. The stability problem has become more complex for the erosion accumulation area under the valley. In this paper, firstly the stability of the tunnel portal is classified. Combined with engineering cases, the FEM numerical method is used to simulate the supporting structure and construction process of the tunnel. Based on the distribution of the plastic zone and displacement of surrounding rock, the mechanism of the instability of the tunnel portal is analyzed. Through the optimized construction scheme that arranges pile foundation in tunnel arch foundation, the bearing capacity of foundation has been greatly improved, which has effectively prevented the instability of surrounding rock caused by the slope deformation and foundation settlement. The conclusions that have been drawn in this paper can be used for reference for related projects.

Probabilistic method and fracture mechanics model were combined to analysis the failure probability of structure with multiple site cracks. Comparing the result with probabilistic model showed that, accounting the actual failure mode and the interaction of cracks, combination of probabilistic method and fracture mechanics model get better approaching to determine failure probability during structural integrity analysis.

Three-dimensional (3D) elastic-plastic finite element model (FEM) is adopted to research the effect of side groove on the crack-front J-integral for different size of Compact Tension (CT) specimens. Although the side-grooved CT specimen is widely used in the existing test method, such as ASTM E1820-13, the test data of fracture toughness is varying with the various geometric parameters. Before FE calculation, the material properties of Q345 steel were obtained by uniaxial tensile test, especially for the true stress-strain relationship. In this paper, it focuses on the numerical study of geometric parameter effects on the fracture toughness. Toward this end, the commercial FE software of ABAQUS is adopted to calculate the J-integral. Since the side groove of CT specimen is so important to make the fracture test success, the various parameters of side groove is intensively analyzed for obtaining the accurate J-integral along the crack front, including the effects of the angle, depth and root radius. In fact, the side groove effect is so significant around the crack front that cannot be ignored in the J-integral calculation. Through rigorous FE investigation, the influence of the side groove on the fracture toughness testing is fully disclosed, and the appropriate side groove configuration is recommended accordingly.

Compressive residual stresses have been found to affect fatigue crack growth behavior by delaying the crack initiation and by decelerating the crack propagation rate. Therefore, various mechanical surface treatment techniques have been developed to produce the compressive residual stresses on the surface of components. However, the residual stresses will relax due to cyclic loading. Hence, the stability of residual stress during fatigue process is a great importance aspect for design of components. In this paper, the ultrasonic surface deep rolling was used to generate the compressive residual stress near the surface of Ti-6Al-4V. The stress relaxation behavior was identified during the low cycle fatigue process. The X-ray diffraction method was used to determine the magnitude and sign of residual stress. Results showed that under cyclic loading, the residual stress relaxation occurred fast in the first few cycles then became stable. Furthermore, it was found that relaxation rates of residual stress were depended on the applied stress.

This paper presents the global convergence theory of the discrete-time uniform pseudo projection anti-monotone network with the quasi–symmetric matrix, which removes the connection matrix constraints. The theory widens the range of applications of the discrete–time uniform pseudo projection anti–monotone network and is valid for many kinds of discrete recurrent neural network models.

For the study of first conveyor chain dynamics behavior when it is started and seek the theory basis for the chain breakage on first conveyor, set up the mathematical model of the first conveyor and its scraper chain by using finite-element method. And then did the dynamics characteristic analysis between scraper chains with material, set up the differential equation. Took advantage of the mathematical model and the differential equation, and combined with the type of EBZ160 road header's technical parameters, did dynamic simulation. It draw a conclusion that during the start-up process the chain speed fluctuates a large range between, the maximum stress value on scraper chain is 1.15×104N appeared after 1s, chain tension adjustment time is about 10s, the biggest adjustment time is 12s.

The paper established real-time computing algorithm of S Curve to control the process of acceleration and deceleration for step motor on the basis of a reasonable start frequency. Moreover, this paper used economic embedded ARM STM32F103RCT as the main control chip to control the step motor, which realized this designed real-time computing algorithm. Finally, the relevant testing indicated that the algorithm can realize the rapid response of start and stop for step motor, and can effectively avoid undesirable phenomenon of step losing, overshoot and oscillation.

In this paper, the low cycle fatigue crack initiation life was regarded as a process of damage accumulation and a damage accumulation model was established based on the Continuum Damage Mechanics. By the model, we analyzed how the variable amplitude applied at the crack initiation stage influenced the low cycle fatigue life of high temperature materials. With the parameters of GQGH4169 alloy at room temperature, we determined the specific values of damage parameters by finite element method and numerical analysis method. Then, the crack initiation life predictions were carried out. The results show that using this approach can not only predict the crack initiation life of CT specimen accurately, but also reflect a definite influence of variable amplitude on the crack propagation life combining with the Paris Law, and the test costs reduced consequently.

How to find most relative factor in multifactor system and how to find the function between relative factors and result are very important. In this paper, Bayes is used to find the most relative factors, then the training dataset is clustered by AGNES(Agglomerative Nesting) , then the section polynomial fitting is used to formulate multiple function for those most relative factors. Finally, this method is applied in the eye sight analysis system, and satisfying results can be obtained.

Digital Volumetric Speckle Photography (DVSP), which is the extension of 2D digital speckle photography, is applied to measure the interior deformation and strain of the object by 2-step 3D FFT. For using FFT, DVSP has some advantages in computational efficiency. With the special loading setup for Micro-CT, the coal specimen under different uniaxial loadings is scanned, and the volumetric images are acquired. By using DVSP, the interior 3D displacements of the specimen are obtained, and then the equivalent strains and volumetric strains are estimated. Based on the interior displacement and strain mappings, the process of deformation or strain localization in the coal specimen is studied.

In recent years, the research on the mesostructure of the concrete by using numerical simulation has been a hot topic. Mesoscopic research would contribute to reveal the concrete cracking failure mechanism. In this paper, the aggregate, the mortar , the interface and the pore are segmented based on CT images . With the aid of Mimics software, the numerical model for ANSYS is built. Besides this, the concrete specimen under uniaxial compression is scanned by using micro-CT in situ. The volumetric images under different loadings are acquired. By using digital volumetric speckle photography (DVSP) method, interior 3D deformation is obtained. Combined with the experiment results, the numerical model is optimized. Based on the optimized model, mesoscopic mechanics of concrete is analyzed by using numerical simulation.

Developing a true 3D experimental stress analysis technique has been the holy grail of solid mechanics researchers since the genesis of the field. Combined the high-resolution x-ray computer tomography (Micro CT) with the 2D speckle photography technique developed by one of us (Chiang), we recently proposed a new 3D strain analysis technique called Digital Volumetric Speckle Photography (DVSP). The elements of DVSP technique are as follows. A reference volumetric image of the specimen is recorded by a Micro-CT scan and stored as a reference. Under load the deformed CT image of the specimen is also recorded. Both volume images are divided into subimages of certain voxel arrays. Each corresponding pair of the subimages are ‘compared’ via a two-step 3D Fourier Transform analysis. The result is a 3D map of displacement vectors representing the collective displacement experienced by all the speckles within the subset of voxels. Strain distribution of the entire specimen can then be calculated using appropriate displacement strain relations. Application of this technique to strain mapping of red sandstone and composite are presented.

The feasibility of one strategy of bioaugmentation was assessed to enhance copper extraction from chalcopyrite. Bioaugmentation consisted of the re-addition of one iron/sulfur oxidizing acidophile (Acidithiobacillus caldus, Ferroplasma thermophilumorLeptospirillum ferriphilum) into the early stage (on the 5thday) of the bioleaching system. The strain selection and inoculum concentration of bioaugmentation were separately investigated by comparing changes in the bioleaching performance and leached solid residues. Results indicated that bioaugmentation with three augmented strains synergistically promoted the total microbial growth and increased the cell numbers, and then accelerated the iron/sulfur oxidation, thereby catalytically regenerated the copper leaching agents of Fe3+and H+compared to the unamended control. Finally, an enhancement in copper extraction was detected and moreover positively correlated with the introducing cell numbers. Particularly, re-addition ofL.ferriphilumon the 5thday showed the best improvement in copper leaching, which remarkably shortened the incubation time (12 days) of almost full copper extraction while only 85.8% of copper was leached after 24 days in the control. Therefore, bioaugmentation could be a useful bio-remedy to improve the bioleaching kinetics and level of copper ore.

Treatment technology of brominated epoxy resin (BER) is still a big challenge to waste printed circuit boards (PCBs) recycling. In order to make full use of the materials, ionic liquid 1-butyl-3-methyl imidazole chloride ([Bmim]Cl) was used to dissolve BER to separate glass fibers from PCB nonmetallic powders. The effects of dissolving parameters including temperature, time and solid/ liquid ratio on the dissolution rate of BER were investigated. The dissolved BER were regenerated and were characterized by FTIR and thermal analysis. Results showed that [Bmim]Cl was a good direct solvent for BER dissolution and at a suitable condition of 170°Cfor 6 hours with solid/liquid ratio of 1: 20 (g/g), nearly 90% of BER in original powders were dissolved. The possible dissolution mechanism was also discussed.

The most significant issues in printable electronics fabrication are the printing quality and efficiency delivered by drop-on-demand (DOD) industrial inkjet printhead. Aiming to characterize the nonlinear behaviors of piezoelectric inkjet printhead, the dynamic lumped element model (DLEM) is proposed to cast the original LEM into a time-varying and nonlinear fashion. At the same time , the PSO-based optimization for paramenters is incorporated in DLEM. Due to new characteristics, DLEM can accurately simulate the inkjet-printed nanosilver droplet formation process and effectively predicate optimal combinations of high-frequency driving waveform with high printing quality. From extensive experimental studies, the effectiveness and efficiency of the proposed DLEM is validated.

The use of wind power has been rising up rapidly due to its power potential and the improvement of technology. In order to extend the max capacity of power output, the size of wind turbine should grow simultaneously. Therefore, a cost effectiveness of wind power plant is needed to improve the performance. This paper aims at designing a novel hydraulic pitch actuator to implement pitch control effectively even if an impulsive wind peak appears. By developing a novel hydraulic pump control system, the creative design of hydraulic pump control system comprising a fixed displacement pump driven by a servo motor, two unsymmetrical hydraulic cylinders, and hydraulic circuits, could have an excellent response in operation. Furthermore, a feedback linearization controller was designed to compensate for the nonlinearity of hydraulic system and overcome the impulsive loadings from wind peaks. The turbine model was built through FAST released by NREL and the dynamic performance showed the excellent robustness and response with that proposed controller and mechanical design.

Owing to the dynamic and competitive business environment, manufacturing companies take real-time monitoring and rapid decision making based on RFID applications, which brings huge volume of information and events generated in the defined manufacturing workflows. Complex Event Processing (CEP) is introduced to solve the problems mentioned above. CEP is applied to handle diverse and large amount of low-level multiple data and primitive events for the purpose of identifying meaningful event patterns. It is very important to integrate the CEP technology to the manufacturing workflows. In this paper, we provide a novel framework of RFID-based complex event processing system for assembly manufacturing applications like cars and high-speed trains. It bridges the hardware in workshops and enterprise applications. The Complex Event Management System (CEMS), which is the kernel of the framework, can filter the irrelevant events and work with uncertain data. Furthermore, a concrete example is used to describe the framework and validate the feasibility in assembly monitoring of the car manufacturing.

Geotextiles are made of polymers, and their conjunction with different processes and materials can provide geotextiles with desirable characteristics and functions, such as filtration, separation, and drainage, and thereby meets the environmental requirements. Chemical resistant and mechanical strong polymers, including polyester (PET) and polypropylene (PP), are thus used to prolong the service life of the products made by such materials. This study proposes highly air permeable geotextiles that are made with different thicknesses and various needle punching speeds, and the influences of these two variables over the pore structure and mechanical properties are then examined. PET fibers, PP fibers, and recycled Kevlar fibers are blended, followed by being needle punched with differing spaces and speeds to form geotextiles with various thicknesses and porosities. The textiles are then evaluated for their mechanical strength and porosity. The test results show that a thickness of 4.5 cm and 1.5 cm demonstrate an influence on the tensile strength of the geotextiles, which is ascribed to the webs that are incompletely needle punched. However, the excessive needle punching speed corresponding to a thickness of 0.2 cm results in a decrease in tensile strength, but there is also an increase in the porosity of the geotextiles.

To explore the isolation mechanism and optimize the performance of the porous material in a dynamic viewpoint, a nonlinear porous material vibration isolator is modeled in this work. The stiffness of the isolator is regarded to be a piecewise linear, according to the stress–strain characteristics of porous material. Averaging method is employed to analyze the amplitude-frequency characteristics when the system excited by harmonic excitation. It is found that the vibration system represents linear, bilinear and tri-linear characteristics, when the porous material isolator works in linear-elastic phase, plateau phase and densification phase, respectively. The result shows that the amplitude response of the system in the plateau stage is much less than the linear isolator.

In order to solve the potential safety risk of traditional industrial remote control, a deep research on embedded and wireless communication theory has been done and a wireless remote control system with the C8051F120 single chip as the main control chip has been invited. Data can be sent and received steadily between transmitting terminal and receiving terminal in this system even in unfavorable environment, which largely improves the safety and reliability for long-distance operation. This system, with the feature of small size, easy installment, low power consumption and excellent wireless transmission, can be applied to industrial machinery such as pump car and wall-climbing robot.

To study the fatigue damage of a cutter used for cutting cashew nut, the integratedsimulation platform is established with Hypermesh, LS-Dyna, LS-PrePost, and nCode GlyphWorks.The simulation model is established by Hypermesh. LS-Dyna is used to calculate the k file.LS-PrePost is used as the post-processing software. The rain-flow counting, load superposition andextrapolation are executed using Rainflow module in nCode GlyphWorks. The analysis of thefatigue damage of the cutter is executed using Stress Life module in nCode GlyphWorks. Theequivalent stress time history of different elements in the upper and lower cutters, rain-flowcounting histogram after load spectrum superposition, rain-flow counting histograms after loadspectrum extrapolation, and damage histogram of the cutter are obtained. The results show that thecutter has excellent mechanical properties, and the minimum fatigue life of the cutter is about 495days, which is a conservative solution.

Taking the effect of geometric errors on machining accuracy into consideration in the design of small precision machine tools, the thermal errors become the main factor affecting the machining accuracy of machine tools. Currently, how to quickly and effectively evaluate the impact of thermal error on machining precision, in order to make effective thermal error prediction and compensation method, is needed to solve for small precision machining. Based on stepwise regression algorithm theory, combined with the DBB measured and analyzed on MATLAB in this paper, a better thermal error fitting regression formula is obtained. Meanwhile, this mathematical model approach is also applicable in a variety of other areas, such as machine tool thermal error analysis, compensation and testing etc.

Resources of wind power due to its presence greater volatility, increasing the difficulty of regulating for the power grid. In the supply side, by installing thermal storage device to the cogeneration units so as to increase the adjusting capacity in the supply side of the power system, in the load side, the wind power heating system added heat storage device, increasing the load that can be adjusted. These two measures could be better to solve the problem that part of the abandoned wind. In this paper, analyzed the theoretical basis of each system briefly, added thermal storage device in electric –thermal combine system, and the thermal storage device installation position has been described too. Due mostly theoretical on thermal storage device is about the thermodynamic aspects, it is rather strange for electricity workers, so in this electrical-thermal combined system, its thermal storage devices and electric boiler thermal model have been made a simple analysis and described its control strategy. The control strategy was a comprehensive coordination to the power grid, meanwhile, taking into account the hysteresis characteristics, delay effects and daily regulation plan features of the thermodynamic parameters of thermal storage system make a reasonable start-stop control strategy finally.

This paper is concerned with the design and implementation of a ZigBee based wireless sensor and actuator networks, which has been applied in our service robot intelligent space successfully. Firstly, an overview of ZigBee protocol is given, and then the design and implementation of hardware module and software stack of ZigBee based wireless sensor and actuator networks are addressed in detail. Some representative devices are described, including environmental sensors for environmental perception, home devices controllers for device control, IMU module for abnormal behaviors detection, locating system for node localization and laser robot control for service robot navigation. Application example is described to demonstrate how the devices in ZigBee based wireless sensor and actuator networks to provide service cooperatively. Finally, we conclude this paper and discuss the future directions.

As wind power generation rapid development in china, wind power prediction is the key to the system operate safely. Given significant uncertainties involved in wind generation, probabilistic interval forecasting provides a unique solution to estimate and quantify the potential impacts and risks facing system operation with wind penetration beforehand. this paper based on the point forecast, calculate wind power prediction error, formulate the distribution of prediction error, you can get the historical probabilistic distribution of prediction error, use the distribution of error to build the risk assessment of wind power after prediction, give the fluctuate range of predicted values. Probabilistic interval forecasting can obtain the probably of power system operation safely and reliability assessment criterion.

With the rapid development of mobile communication technology, mobile e-commerce market transaction scale has exploded. The O2O model is facing great opportunities that an effective combination of Online to Offline. As the largest instant messaging software users of the Asian area, the wechat is bringing unlimited business opportunities for O2O model. This paper constructs a wechat platform system taking "the wechat public platform" as the core, the paper discusses the realization strategy of the O2O model based on the wechat platform technology, and it analyses the long-term operation mechanism of the second development of this platform system.

Based on the feature of large thickness and poor drawing characteristics in extremely thick coal seam top-coal caving method, combined with numerous practical examples analyses, the primarily six factors influence the drawing characteristics were found out which are mining depth, coal seam strength, joint crack development, parting thickness in top-coal, caving ratios, immediate roof filling coefficient. According to 45 typical top-coal caving in extremely thick coal seam samples, the prediction of top-coal caving and drawing characteristics based on artificial neural networks was established and training samples and testing samples was determined. Use SPSS statistical software training the network model. Then select No. 9 coal seam first mining area of Tiaohu mine as the application case. The drawing property was forecast according to the established network model. Application results show that the use of artificial neural networks for top-coal caving and drawing characteristic prediction is effective and feasible.

With the improvement of requirements for vehicle comfort, people put forward higher requirements on the noise control of automotive air conditioning. As the power source of the automobile air conditioner, the compressor is also the main noise sources, so it is the major objective of vibration damping and noise reduction. In this paper, with analyzing the noise mechanism of compressor, introduces four identification methods of automotive air conditioning compressor noise source, providing theoretical basis for automobile air conditioning damping and noise reduction.

A new flash boiling spray model whose atomization criterion based on the void fraction and superheat while evaporation model based on the dual-zone method is established to simulate the flashing sprays. The model function is implemented in KIVA program. Flash boiling spray model predicts spray penetration and spray cone angle and its development trend, in good agreement with the experimental results. The model has a good capability in simulating flash sprays at low superheat conditions, which breakup is controlled by void fraction, as well as high superheat transition process. It can also predict flare flashing sprays to some extent at higher superheat conditions.

ZigBee is a low-rate, low-power-consumption wireless communication technology, which can be widely used in the Wireless Sensor Network (WSN). ZigBee wireless network is applied to the monitoring system of gas flow meters in this paper. The design of hardware and software of the system based on Zigbee chip is given. The gas flow data is uploaded to the terminal node via RS485 serial port, and the terminal node transmits the data to the coordinator by the ZigBee wireless network, and then the coordinator sends the data to the PC by using RS232 serial port. In this way, the monitoring center can manage and analyze the data, so the real-time monitoring can be realized. It has been proved that the system has strong anti-interference ability, safe and reliable and stable operation.

In order to study the working features of automotive air conditioning scroll compressor, this paper uses mathematical model of working process to analyze it. After studying working process, a equation of suction volume is given. The thermodynamic model of compression chamber and back pressure chamber includes mass conservation and energy conservation. Based on Hydromechanics, leakage models of radial leakage and tangential leakage are discussed. The model lays a foundation of automotive air conditioning scroll compressor performance simulation.

The energy of the nodes in wireless sensor network is very limited. Power supply module power supply, not only need to give themselves also need to collect data of the sensor power supply, monitoring data sending and receiving, processing, also need to consume energy. If the node due to run out of battery and enter a state of "death", can cause the node collection data loss; If the node is terminal nodes, only this node data loss; But if the node is routing nodes, not only can cause data loss of this node, also can cause by all nodes of the node for data transmission loss of data. So, the question of energy consumption becomes a research focus in the field. Through the architecture of wireless sensor network and the analysis of the wireless sensor network protocol stack, according to the characteristics of the wireless sensor network (WSN) and energy optimization strategy of background points out the necessity of energy optimization. By analyzing the energy consumption of wireless sensor network, the wireless sensor network energy optimization strategy is given.

Based on the hurricane evacuation process, the dynamic characteristics of hurricane disaster risk were analyzed. The degree of harm and endanger regional are the two aspects of dynamic characteristics of hurricane disaster risk and by use the hurricane center and hurricane levels, the risk measurement method for a given point was proposed. The new emergency evacuation strategy was based on the largest decline of unit risk which was also the main idea of vehicle steering decision function. By the hurricane evacuation examples, the case that traffic net with traffic bottlenecks was studied by simulation. The results show that the proposed hurricane emergency evacuation strategy of this paper is feasible and have practical implications.

The paper extends the traditional lumped parameter analysis method of unsteady-state. Under the convection boundary 0

According to the vehicle after geomagnetic disturbances cause of this phenomenon, in-depth theoretical study of the anisotropic magnetoresistance AMR sensors, using triaxial anisotropic magnetoresistive sensor HMC5883L design a vehicle detection system. The system consists of a sensor module, wireless communication module. Sensor nodes through wireless communication module connected with the host computer, to achieve the detection of vehicle information.

Sediment layer can change the dynamic property of reservoir water. As a result, the dynamic response of dam body would be affected. In this paper, the sediment layer is simulated as saturated liquid-solid two-phase media, and the finite element model of gravity dam-reservoir water-sediment system is established with the gradual enlargement mesh method. Then the influence of sediment layer on seismic wave motion is studied with this model. The calculation result shows that the energy radiation of far field of foundation, reservoir water and sediment can be considered efficiently in this model, and with the thickening of sediment layer the dynamic water pressure on dam face decreases.

In this paper, a new method using wavelet packet energy spectrum to identify transformer inrush and internal fault current was proposed. Wavelet packet transform respectively decomposed inrush and fault current, then calculated the energy of each frequency band of decomposed signal. Finally, the conclusion showed that the energy of internal fault in high frequency band is much less than that of inrush. The difference was quantified and it could be observed intuitively. Through extensive simulations, this paper proves that the method in terms of identifying transformer inrush is accurate and effective.

For getting the coordinate of contactor on CCL, the measurement system transformed resistance into voltage by providing constant current on CCL. The system includes MCU, 3A constant current source, MOSFET switch circuit, signal amplifier circuit and A/D converter. By the curve-fitting method, the equipotent lines of CCL were simulated with MATLAB according to the discrete data. The equations of equipotent lines were obtained with second-order polynomial fitting method. The two curves which the contactor located in were acquired with local linearization method, and the coordinate was gained by calculating solving equation groups.

The structure of cast iron specimen and the temperature control unit of the engine coolant ultrasonic cavitation apparatus were improved in this paper. The broken problem of cast iron specimen was solved by split-structure design, which also solved the loose binding problem between specimen and sonotrode. The temperature control unit included a beaker with water circulating jacket, water bath, circulating pump and connection hose. The temperature control unit overcame the difficulty of the temperature control of test coolant solution. More important, the temperature control inside the soundproof box was realized, which avoided the effect of ultrasonic vibration noise on the health of operator. The unit has the characteristics of simple, practical and easy to use.