Applied Mechanics and Materials Vols. 198-199

Abstract: This paper proposes a method to control the gain of an amplifier. A 6-bit digital signal is used to control the gain of the amplifier by adjusting the resistance of a potentiometer. The change of the digital signal is allowed to change the gain of the amplifier only if the input signal of the amplifier crosses alternating current (AC) zero. The gain of the amplifier could be reduced or restored, which is based on whether the output signal of the amplifier exceeds a predetermined value or not. The method is verified in a class D amplifier. Road test shows that the method may eliminate the glitch caused by gain change, and the clamp caused by a too large gain.

Abstract: In this paper, a study and analysis of a distance measure method based on single vision with the aid of a laser pen is proposed. In the method, a camera and a laser pen are used as measurement device. By comparing the lightness of the pixels, the laser point projected on the object is found out in the image. Then an orthogonal triangle using the distance between laser point and CCD center as one edge is set up. And Pythagorean Theorem is applied to calculate the distance between camera and measured object. Experiments in different lightness are carried out and encouraging results are obtained which prove that the device has nice measuring performance in appropriate lightness.

Abstract: A single mode fiber assembled with a specified length graded index multimode fiber as a collimator, which is used in common-path optical coherence tomography (CPOCT) is described in this paper. Compared with conventional collimator lens, this assembled fibers structure possesses the advantages of small volume, easy to be fused or connected with other part of the CPOCT system. Furthermore, with this assembled structure an all fiber CPOCT system is constructed which has the potential to detect the internal bodily organs and tissues of human being. Numerical simulation and experiments are implemented to verify the effectiveness of this method.

Abstract: In this paper, a novel charge pumped clock generator is proposed, which can pump the reference cock to a level as high as double Vcc, while keeping the low level of the clock unchanged. The proposed circuit is very suitable for low voltage IC design to attain low on-resistance of MOS switch while keeping the parasitic capacitance small, which results in high speed of the circuit. The stimulated results show that the pumped clock has rising and falling time of 50ps and 67ps respectively.

Abstract: Aiming at the problem of high energy consuming and failure rate on traditional AC contactor, the implement method of intelligent AC contactor is presented. The smart structures concept is introduced into the domain of AC contactor and the microcontroller C8051F040 is used as the control core. The intelligent AC contactor is a comprehensive system which assembles data acquisition and control, fault self-diagnosis and protection Function, etc. DC operation and on-line monitoring of the running state is also realized. Experiments show that the system has characteristics of low cost , accurate indication for running state and fault location, good protecting function, completely eliminating the noise and vibration operation, good performance in energy-saving , etc.

Abstract: The deflection which reflects the bridge linear variety is an important parameter for the evaluation of bridge safety. According to the structural characteristics of urban bridges, the connected pipe optoelectronic liquid level sensor system is a novel kind of sensor for detecting the connected pipe liquid level, which can be applied for multipoint, long-period, online, remote, automatic measurement of bridge deflection, it is not affected by the dust, humidity and fog in the urban bridge health monitoring and maintenance. At present, the system has been integrated and applied in the project of main roads bridge Online Safety Monitoring Management System in Hangzhou (Phase II), a web-based urban bridge cluster monitoring system have been established since 2007. According to a tied arch bridge case studies, the measuring data show that the system not only can accurately collect the bridge normal deflection information and variety, but also successfully monitored the structural responses due to the Wenchuan earthquake on May 12, 2008. About two-minute abrupt changes in displacement amplitude were observed in the measured signals starting at 14:37, about 9 minutes later than the earthquake’s occurring. The results shows, it is an effective method for the real-time monitoring of urban bridge deflection.

Abstract: The correction methods of LED displays are aiming to address the uniform issues which includes brightness aspect and color aspect. The correction method use a 3×3 correction coefficients matrix to reshape the pulse width of each LED.To calculate the correction coefficients, a linear system is established, which includes a color CCD and a LED display. And a correction algorithm is introduced based on the color CCD. This algorithm describes the relationships of the main color components of a LED, when the gray level of a LED is increasing or decreasing, the three main color components would change according to the correction coefficients. The results shows that the correction based on this algorithm improved the performance of LED displays.

Abstract: The thesis analyses the noise of the strain gauge driving circuit in order to obtain high resolutions. With the analysis the thesis points out the methods to reduce the noise. The thesis also draws the conclusion that an amplifier with lower noise spectral density but wide bandwidth perhaps is not suitable for the driving circuit.

Abstract: Speckle correlation fringes include a large quantity of speckle noise. It is first to consider how to reduce speckle noise before using phase formula to calculate. Filter is usually used to reduce speckle noise. From two aspects of frequency domain and space domain, we adopted mean filter, medium filter, Butterworth low-pass filter and homomorphism filter to process the speckle correlation fringes obtained by experiment. It is shown that the speckle correlation fringes are clearer and more easily interpreted and automatic processed after being filtered.

Abstract: This paper introduced the MULTISIM software and its application of electronic technology curriculum design method. The complex circuit analysis and design are finished using circuit simulation completion, changed the traditional design method.