Applied Mechanics and Materials Vol. 620

Abstract: In order to obtain higher cam quality, the research on the cam contour error is studied. The cam is machined in the way of X-C biaxial linkage motions. The linear motor drives the grinding wheel mechanism to get the motion of X axis, and the motion of C axis is the rotating of cam driven by the torque motor. Because of the servo-system-lag of the two axes, the cam contour error is formed in the X-C biaxial linkage motions. Moreover, the following position error of X axis and C axis is not same as the cam contour error. The relationship between axis following position error and cam contour error is studied. The mathematical model of cam contour error is constructed, the relationship between the cam contour error and the following position error are obtained. At last, the conclusion which the cam contour error can be controlled is made, although the following position error exists at the same time. To design the contour error controller for higher quality cam is based on the above conclusion.

Abstract: The stability of high rock slopes under the flood discharge atomization and rainfall is an in-negligible problem especially for the hydropower station with high head during the flood discharge. According to the complicated geological conditions of a high rock slope with the flood discharge problem in China, the method of the saturated-unsaturated unsteady seepage if used, thus the finite element model for the high rock slope in the downstream of the power station is set up. Based on the model, the distribution regularities of the unsteady seepage field of the rock slope is studied under the different discharge atomization and rainfall intensity. Moreover, based on the theory of continuous-discontinuous deformation, the finite element model is set up to analyze the stability of the slope, thus the deformation law of slopes under the flood discharge atomization and rainfall is studied and the safety of the slope is evaluated, and what's more, the engineering measures for improve the stability of the stability of the slope is put forward.

Abstract: The intelligent model of micro gird got more and more attention, which is believed to be the development trend of low carbon intelligent micro grid. In this paper, we construct a stand-alone AC-DC micro gird with wind/photovoltaic/battery resources under off-grid model, and discuss the strategy of micro grid monitoring to realize reasonable allocation of power energy by the control system of unified micro grid dispatching. The electricity generation is integrated to the building grid by 380V low voltage, mainly to meet the self-occupied. The excess electricity can also be stored or connected to the network according to technology and management requirements of countries distributed photovoltaic systems.

Abstract: In order to overcome the shortcomings of traditional quartz crystal microbalance (QCM) network measuring method, such as high requirements for hardware devices, low measurement speed and high challenge to curve fitting, a method based on the Quadrature Demodulation was proposed to design a rapid and accurate measuring system for QCM parameters, which mainly took the advantages of Quadrature Demodulation to remove the intermediate frequency component while reserve the low frequency component. Furthermore, the effectiveness of this method was proved by contrasting the Matlab simulation results with the actual measurement results based on the modified measuring system, which indicated that the frequency resolution could reach 0.1Hz with high testing speed of 0.02s per cycle, the relative deviations of resonance frequencies were less than 0.01% and the deviation of the differences between series and parallel resonant frequency points was 0.38%.

Abstract: This paper introduces the broken shaft failure problem of vacuum pump often encountered, and through the failure mechanism analysis of broken shaft in several aspects, the paper not only summarizes the cause of broken shaft vacuum pump, which is found in five main aspects of broken shaft vacuum p

Abstract: Wireless video surveillance command system is widely used in the public security, transportation, water conservancy, urban management, electrical repair, emergency response projects and other industries. Vehicle-mounted wireless video surveillance system can promptly return the scene to command center using wireless networks. So it is easy for remote visualization, command and control. And it will greatly shorten the reaction time of the accident processing and enhance emergency response capabilities. Mobile evidence obtaining front-end is the most important part of the wireless video surveillance command system. The performance of front-end equipment determines the efficiency of the whole system. So the mobile evidence obtaining front-end is a system design difficult. The following is about the design and implementation of the mobile evidence obtaining front-end of the wireless video surveillance system.

Abstract: The statistical histogram algorithm is one of the common background update algorithms. Considering the statistical histogram algorithm disadvantages of large complex computation, the paper proposes an improved method named fixed window statistical background updating algorithm. The algorithm sets a window which contains N records for each pixel point firstly, every record records value in the permissible range of error and the number of pixel point occurrence, and then counting pixel values for every record through statistical histogram algorithm. When the window is full, the new pixel values will replace the smaller counting, while the pixel which counting larger will be adaptively updated by adaptive background updating formula. The experimental result shows that this method has a high real-time performance and robustness in background updating.

Abstract: Structure’s strain reflects the stability of the project, the excessive structural strain will destroy the stability of the structure. Fiber Bragg Grating has many features, such as, strong anti-interference ability, low optical loss, and it can be used for a long time in the project, etc. Base on the features, the Fiber Bragg Grating Strain Sensor can be used in slope and other projects for the long-term monitoring. In this paper, we develop a Fiber Bragg Grating Strain Sensor based on the spring-steel pipe, FBG be fixed to the inner of the steel pipe by epoxy glue, it is protected by a stainless steel pipe outside, the Flange be fixed to the both side of the spring-steel pipe. When the tension acting one the flanges, the spring-steel pipe occurs an axial strain, this axial strain makes the center wavelength of the Fiber Bragg Grating change, measuring the wavelength shift amount of the Fiber Bragg Grating can calculate the strain. The loading experiment indicates that the sensitivity of the Spring-steel pipe Fiber Bragg Grating Strain Sensor is 0.81pm/με, the linearity of the sensor is 2.1%FS, and the repeatability error of the sensor is 2.29%FS.

Abstract: Seepage control is one of the important problems when designing a hydropower station. The upper reservoir of one hydropower station was built by excavation and backfill partly. Its impermeable program is the combination by concrete panel, geomembrane and vertical curtain. With the finite element method , the model of the dam has been built. The potential distribution of groundwater in the library on the seepage filed is analyzed. It also analyzes the seepage slope of dam body, dam foundation and reservoir and calculates the seepage discharge and replenishment at the situation of normal storage level. The results show that potential distribution law of reservoir seepage field is clear and definite. The effect of cutting water head by anti-seepage curtain and curtain downstream under protective layer at the bottom of the coarse sand and back packing drainage is remarkable. The panel and geomembrane have an effect on cutting waterhead. The seepage flow of upper reservoir is 488.16m³/d and the supply flow is 1019.52m³/d. So the control scheme of the upstream seepage is reasonable technically.

Abstract: This paper starts from the influence of vehicle exhaust, first introduces a major vehicle exhaust monitoring technology--Remote Sensing Technology, gives its monitoring principles and then analyzes the advantages and disadvantages of this method. Then,it takes the most abundant types of substances in vehicle exhaust (NO_x) as example,illustrates the principles and methods for monitoring. Finally,it introduces a new vehicle exhaust monitoring method and makes a full summary.