Advanced Materials Research Vols. 301-303

Abstract: There are many faults in microwave power measurement in the working spots. In this paper, the novel technique of microwave power measurement and Schottky detector and the technique of soft-measuring based on improved BP neural network are presented. Making use of directional coupler, the part of power of microwave signal in transmission line was taken in the certain proportion. Then, the microwave power meter indicated the magnitude of power. The microwave power measurement system was composed of tuneable attenuator, directional coupler, matching load, peak-peak value detector, oscillograph, thermocouple, soft-measuring algorithm and so on. The low microwave power meter obtained the sample data of training BP neuron network. Then, the output of trained BP neural network may represent the result of high microwave power measurement. The experiments and applications in practice project prove that this new method has many advantages.

Abstract: Photometric stereo is a widely-used non-contact optical technology for surface shape measurement in industry. However, it is subject two limitations: (1) all light directions used should be known; (2) reflection on the surface to be measured should obey the Lambertian model. In this paper, an extended photometric stereo is proposed to overcome these limitations. Firstly, initial light directions are estimated in terms of normals of those points on the silhouette; secondly, an iterative process is established to refine alternately both the normals and all light directions, with specular pixels removed; at last, the final surface shape is worked out by integrating the normals. Experimental results show the considerable feasibility of this algorithm.

Abstract: Due to the lack of valid testability evaluation methods for complex equipment in the final phase, a new testability evaluation method based on test data in development phase is proposed. The problems that classic statistic method can produce the conclusion with low confidence level and high risk under the condition of small sample are effectively solved. This method adopts mixed prior distribution and determines the inheritance factor by using chi-square goodness of fit between the history test information and the field information. Finally, the fault detection rate of certain large-scale radar equipment is validated. The analysis result of the practical case proves that this method can produce evaluation conclusion with high confidence level, and shows that this method is more rational than the classical statistical method and the traditional Bayes method.

Abstract: This paper presents the high-speed ultrasonic testing methods for steel pipes currently, and points the existing difficulties, such as the instability in signal transmission, the problem of water coupling, and so on. Then the inspection method based on linear reciprocating probes is proposed to achieve the purpose of fewer probes and higher detecting speed. The mathematics model which adopts the slider-crank mechanism to realize the probes swinging fast in line is established as there is blind spot between the adjacent probes in high-speed inspection. With the help of simulation of Matlab, the relation curve between the rotation speed of crank and the rotation angle of crank is acquired, as well as the line speed of the steel pipe and the rotation angle of crank. The experiment platform is set up according to the simulation data, and the results verify the feasibility of the method.

Abstract: Since there are few methods to evaluate the qualitative index in dam safety monitoring and the evaluation system is imperfect, in this paper a new quantitative and comprehensive evaluation method for qualitative index is explored with the introduction of the method of interval marking, Set-Valued Statistics, grey theory and Jousselme distance function. Firstly, the interval marking method and Set-Valued Statistics are used to obtain the comprehensive quantitative value; then the evaluation class of the comprehensive quantitative value is quantified and the evidence vector is obtained through grey theory; next the weights of all qualitative indices are obtained through Jousselme distance function; finally the comprehensive influence of the qualitative indices on dam safety is determined by using the evidence vector and weights. The case study proves that this method is feasible which can reasonably determine the influence of qualitative index on dam safety.

Abstract: The high precision surveying control network provides the positional and orientation datum for the construction and measure-control system of the Five- hundred-meter Aperture radio Sphere Telescope(FAST), which is deployed at the typical Karst depression. The design of the control network is in accordance with the 1:1000 topographic maps. The issues about the control station site selection ,distribution and construction are analyzed and discussed, and the initial results are provided in this paper.

Abstract: Experimental research on transition and flow separation of laminar airfoil and the influence of transition and flow separation on the performance of laminar airfoil are carried through. The experimental device and instruments used in the research are introduced. It is shown from the experimental results that at certain scope of attack angle, flow transition shifts from 50%c to 30%c on the upper surface of airfoil model along with 1 degree increase of airfoil attack angle; For flow speed of 35m/s and 50m/s with attack angle from 4 degree to 8 degree, flow separation position don’t vary but only separation scope increase; For flow speed of 15m/s laminar flow separation on the upper surface of airfoil take place at attack angle of 4 degree, flow become attaching at attack angle of 6 degree and turbulent flow separation take place at attack angle of 8 degree.

Abstract: Spherical swashplate type axial piston pump slipping shoe hole shape and reasonable position design is key points for pump working. Current calculation method which adapted average parameters as final size is not accurate in theory. In this paper ,according to the relationship between geometry and motion of piston pump, coordinate transformation is used three times to deduce motion trajectory equation,and drive motion trajectory curve. The method discussed is precise ，it can be used to provide reference for slipping shoe hole design.

Abstract: The CSIRO overcoring stress relief and hydraulic fracturing methods are the most popular methods used for the measurement of in-situ stress at depth. One major advantage of the CSIRO overcoring stress relief method is that the three dimensional state of stress can be obtained, but the measurement must be done in an excavated tunnel^[1]. Hydraulic fracturing method can be carried out on the ground surface, but it assumed that one of the principal stresses direction is vertical^[2,3]. In terms of the disadvantages of the two methods, the techniques based on core orientation and acoustic emission behavior of rocks are incorporated in the in-situ stress measurement in order to obtain the in-situ stress conditions at depth in Shuichang Iron Mine. According to the comparison of the measurement data obtained from the acoustic emission test in the laboratory and CSIRO overcoring stress relief measurement in the field, effectiveness of the acoustic emission test is confirmed. In addition, the relationships between in-situ stresses and tectonic settings are analyzed. Finally, the distribution of in-situ stresses in Shuichang Iron Mine is given, which provides a meaningful guideline for the following mining and design.

Abstract: In this page, arc imaging system was estabished with the double agglutination lens ,screen , dimmer glasses, aperture and precise mobile platform. The imaging system was aligned by laser, so that clear and magnified image could be shown on receiving screen basing on this system which is helpful for the specific position of measuring temperature . Spectroscopic diagnostics about welding arc plasma were carried out with this system and spectrometer HR4000CG-UV-NIR . Argon I spectral lines were chosen for calculation from welding arc spectrum collected and the modified double-line method was used to calculate arc temperature . The arc temperature measured with this method in this paper is similar to the result reported in the literatures. The experiment results show that the system established to measure the arc plasma axis temperature at fixed point is possible.