Advanced Materials Research Vols. 655-657

Abstract: The effect process between femtosecond laser and matter had been introduced first. Then introduce the theory of strain pulse and the experiment set up.We detect transient reflectivity change on surface of GaAs at different delayed time using femtosecond transient reflection spectroscopy.We found it was made up of three parts: original scattering process of 100fs, carriers-lattice thermal equilibrium of 1.5ps and recombination process of 500ps.

Abstract: In this paper, the self-levitation force of ferrofluid in sensor is simulated calculation under different magnets core in ferrofluid sensor. The relationship between self-levitation force and height under different radius of magnet core, and the relationship between self-levitation height and length of magnet core are obtained.

Abstract: Aiming at the problems such as slow speed and low measuring accuracy existing in measuring length precision of pin parts in mass production, a new approach of high speed and precise measurement is proposed based on the research of the length measuring methods such as parallel laser length measuring method and area array CCD measuring method, etc. Application of (machine vision system and computer measurement & control technology) digital image processing technology can perform automatic high speed measurement and separation of workpiece effectively and accurately. The experimental results show that the machine speed could reach 4-5 pieces/second, with length measuring accuracy of around 10 microns, indicating that the approach proposed in this paper has important practical value.

Abstract: With the domestic aircraft to continuously improve the level of production, digitalization and automation of airplane ground test adjustment technology is transforming it into a requirement, flight test technology will move towards digitization, Integrated ,and commom direction of development. Automation of aircraft wing deflection measurement platform through the development of PLC control system experiment and pc with experimental realization of the process control and real-time monitoring, Established a complete set of data acquisition channel, Promote the development of aircraft wing deflection angle of automated measurement technology.

Abstract: Use electromagnetic simulation software PSCAD/EMTDC to 6 kV power distribution lines for lightning protection research. Resarch the influence of the different measures for the lightning protection level. Finally get a comprehensive lightning protection program.

Abstract: Positioning algorithm in automatic identification system (AIS) is being investigated in the literature due to the importance in safety and national security services. Nowadays, position information in AIS originates from the navigational sensors in extern system. In this paper, we introduce a novel algorithm for ship positioning using both time and time difference estimates, which lead to enhanced versions of the time of arrivals and time difference of arrivals positioning method. Moreover, the accuracy of the proposed hybrid positioning algorithm is evaluated. Finally the simulation results have shown the validity of this novel positioning algorithm.

Abstract: Underwater localization is a key element in most underwater communication applications. Since GPS signals highly attenuate in water, precise ranging based techniques for localization need to be developed. In this paper we describe a modified Short Baseline (SBL) acoustic localization system, in which a scheme of multi-channel data acquisition based on LabVIEW, the Generalized Cross Correlation (GCC) algorithm, and the hyperbolic positioning algorithm are used. Simulation results show that the modified SBL acoustic localization system that we proposed can adapt to the underwater harsh environment better, and also can reduce the position statistical error of underwater target significantly.

Abstract: Geometric dimensioning measurement is a very important application in metrology. In this paper, we focus on the geometric dimensioning automatic detection of tubular member based on the laser displacement sensor. An automatic detection system of tubular member is designed using line laser scanning principle. The system includes base, swivel table, servo motor, motor driver, servo pack, motor controller, laser displacement sensor, data acquisition card, and computer. The system first gathers the displacement information by laser displacement sensor, then performs coordinate transformation and three dimension reconstruction of the tubular member. The external diameter and the roundness error can also be measured. The experimental results show that the geometric dimensioning parameters measurement is effective and accurate using this method.

Abstract: Against the poor accuracy of the vehicle counters extracted by existing vehicle detection technology, a motion vehicle detection method based on self-adaptive background subtraction with cumulative inter-frame difference is proposed in this paper. Cumulative inter-frame difference is used to subtract binary object mask. According to the binary object mask, in the area of moving objects the pixels of last background are used to modify the current background, otherwise the pixels of current image are used. The result of this operation is the current background. Then the background difference method is used to detect moving vehicles.

Abstract: The 3D coordinates of measured point is embodied in 2D image coordinate of the optical characteristic point via the visual measurement system. Based on the gray square weighted centroid localization algorithm, the paper presents bicubic interpolation gray square weighted centroid localization algorithm, increases the number of effective pixels around the optical characteristic point imaging center, and reduces noise error via the gray square weighted, improves the imaging center location accuracy of optical characteristic point, realizes the accurate location of the optical characteristic points. Results indicate application of the proposed algorithm to location, the standard tolerance along the direction of x is 0.0022 Pixel, the standard tolerance along the direction of y is 0.0023 Pixel, compared with the others, the standard tolerance is minimum and discrete to a lesser degree distancing ideal image point, that is, the proposed algorithm has higher location accuracy. The maximum tolerance along the direction of x is 0.008 Pixel, the one along the direction of y is 0.007 Pixel, compared with the other two algorithms, the maximum tolerance is minimum .Results indicate that the stability of the proposed algorithm is better.