The problem of freeform surface reconstruction starting from a cloud of points measured by a laser scanning system is examined. The objective is to fully integrate reverse enginccring and laser scanning for rapid product development. The measuring principle and the configruation of the system are investigated. Based on non-uniform rational B-spline (NURBS) curve and surface, the freeform curve, the surface reconstruction method, the step and parameterization algorithms are introduced. The interfaces between initial graphic exchange specification (IGES) and sterco lithograpgy interface specification (STL) with CAD and rapid prototyping manufacturing (RPM) system are discussed. The system is developed bascd on an open graphics library (OPEN GL) software environment. A practical case is presented to illustrate the cffcctivenessof the approach.

It is a hard nut to crack how to ensure the sensors keep survives to measure the jet flow pressure with several hundred microseconds to about 20 milliseconds under the severe radiation condition with dose rate at 131013 rad (Si)/s and strong explosion shock. A novel method we have proposed with the plastic deformation principle of metal material and pressure threshold can solve the problem effectively, especially in the large scale chemical explosion test.

Aimed at the problems of inferior precision and bad maneuverability for three-dimensional (3D) measurement by projected fringe pattern, a flexible new 3D technique for performing system calibration and measuring was proposed. First, we analyzed the principle of conventional 3D measurement with projected fringe pattern, and pointed out the shortcoming of measurement system. Then, the CCD camera calibration technique is analyzed and we set up the perspective projection model which transforms the computer image coordinate to 3D world coordinate, and we get the coordinate of the CCD camera image lens. Third, the position of projection lens optical center can be obtained using the above model. At last, some experiment results presented show that this technique is more simple and robust in engineering than conventional measurement method.

A three-dimensional profile measurement sstem based on a projection coded grating technoque is presented. The system uses a designing and decoding technique for grey coded gratings. The coded grating has black, white and grey stripes. The period triples a conventional grating. lt greatly increcses the height measuring range without any decrease in stripe separation. The shape of object and be obtainde from only one grating image. The systm is suitable for instantaneous measurement of moving objects including human face. The technique proposed pedmites rapid 3D measurement and no moving parts are involvde in the system. The hardware is relatively simple. Special data processing software is develped. Results of a practical example confirm the effcetiveness of the proposed method.

Potentiodynamic polarization and impedance measurements are used to examine the effects of temperature on the passivation behavior and corrosion resistance of 13 Cr martensitic stainless steel in CO2 and Cl environment. Different specimens are tested during exposure to 90, 120 and 150℃. Reaction mechanisms are decided from polarization curves. The characteristics of the surface film are determined from impedance transfer function model, which involve the reactions occurring at the metal/passive film as well as diffusion processes. Information concerning system electrochemical parameters is used to interpret the effects of temperature on the passive film and corrosion resistance. These results are consistent with the SEM and XPS analysis.