Applied Mechanics and Materials Vols. 333-335

Abstract: A wide range of suspended sediment concentration can be obtained by satellite remote sensing. According to the multi-temporal remote sensing data and quasi-simultaneously surface sediment concentration data, research works on the surface suspended sediment distribution and movement trends of Matakong coastal area, Africa were carried out. The results showed that the suspended sediment concentration of the studied area is not large, and the sediment movement is not active. The sediment source comes from the nearshore shallow flats, where they could be entrained by the wind waves and then diffuses by the tidal currents.

Abstract: Pockets are widely applied in the design of the aircraft structural parts. For achieving aggressive weight targets, pockets are always designed by thin walls and webs. When machining a pocket, the web is created at the face of the end mill, as opposed to ribs, which are created at the periphery of the end mill. However, difficulty exists for control the thickness tolerance when machining these thin-webs. In this paper, the on the machine measurement technology is adopted to help control the thickness accuracy of thin webs. A typical part is taken to illustrate the proposed method and test results show that the proposed method efficiently improves the machining accuracy of thin webs.

Abstract: Microwave power standard adopts calorimetry techniques to calibrate the effective efficiency of the thermistor mount. Correction factor is the key of calibration thermistor mount.The microwave power standard mainly adopted short-circuited mode to determine the correction factor so far, but it must consider the effects of microwave power absorbed by short plate to thermopile, so the method that how to get the power dissipated in the short plate is the key to calculating correction factor and its uncertainty. This paper presents a new method based on electromagnetic field theory to consider the short-circuit dissipation power. A detailed analysis of its superiority over the traditional method is shown. It reduces the uncertainty of the correction factor reasonably, in other words, reduces the uncertainty of the microwave power standard.

Abstract: R temperature measurement in electrical equipment is more and more used in temperature measurement, but accuracy of temperature measurement is susceptible to outside interference. The main factors affecting the accuracy of measuring temperature, such as environmental factors, equipment emissivity and distance coefficient, are analyzed, the solution has been put forward. In the environmental conditions under the condition of relatively unchanged ,change rule of the temperature value along with the temperature measuring distance changing from 0.7 to 5 meters is found, and temperature value is calibrated . The result after calibrating shows that the method is valid,and error of temperature is less than 0.7°C within 5 meters.

Abstract: The principle of an ultrasonic distance measurement system is introduced. The system adopts non-contact measurement method and it consists of signal generator, echo receiver circuit, microcontroller, time sequential logic control circuit, target distance detection circuit, temperature measurement circuit, RS-485 serial interface circuit, ultrasonic sensor and its driver circuit, etc. The results show that the system has high precision within measuring range from 20cm to 15m.

Abstract: Obtaining valid data of accelerating propeller cavitation noise is benifial for finding the relationship between the ship feature and its radiated sound souce. This paper studies the criteria ruling the measurement of accelerating propeller noise signal in cavitation tunnel, and analyzes the signal model of the measured noise. Based on the signal model, the paper studies the fractional Fourier domain analysis method to extract interested cavitation noise from the measured noise.

Abstract: A new technique for evaluating a microcalorimeter is presented in this paper. Its measurement principle is to change a thermistor mounts mismatch status by changing the reference resistance of its power meter bridge, measure a microcalorimeter in different mismatch status so that effective efficiency of the thermistor mount measured by the microcalorimeter can be used as the transfer value. This technique will shorten the measurement time and simplify the assembling procedure, while not reducing the evaluation accuracy. Its measurement principle and a experimental result are reported in this paper.

Abstract: The paper presents the construction of the sensor array and do research on the spatial resolution of EMT system. As it directly determines the detection performance of the system. Rigorous experiment schemes have been designed to test and verify the spatial resolution of EMT system. And then, the application performance of the EMT system is shown.

Abstract: In order to overcome the limits of visual observation widely used in ship draft survey, a digital measurement system based on image acquisition and processing is presented. The images of drafts are obtained by an image acquisition unit containing a high definition camera extended to the shipboard from the deck. The draft marks are digitalized in use of a multilayer neural network, and the draft lines are detected by means of color image segmentation algorithm. Finally, the ship's trim are identified based on the relative position of the draft line located at the digitalized draft marks, where the artificial influences are eliminated. The influences of wave may also be reduced by calculating the mean value of the ship's trim obtained from different images.

Abstract: In order to eliminate the measurement error caused by working voltage fluctuation of weighing sensor, a dynamic voltage compensation method for improving the weighing accuracy was proposed in the paper. The method takes strain gauge type pressure sensor as the weighing sensor and corrects Wheatstone bridge circuit. By synchronously detecting output voltage signal and working voltage of the weighing sensor, the method dynamically compensates the working voltage fluctuation of the weighing sensor, corrects the measurement error caused by the voltage fluctuation of external source and calculates the weight in real time. A weighing system based on the digital signal processor (DSP) was designed. Results of simulation experiment verify the feasibility of the proposed method.