The paper presents the structure of remote fault diagnosis and maintenance system based on Internet, and it is deeply studied
to the realization of data acquisition and information integration by means of OPC and XML technology and it also makes a
brief discussion for the design of remote maintenance center. The key point technology and system structure presented in
this paper establishes the technique basis of resolving the bottleneck problem of remote fault diagnosis system.
Measuring the shape of a model is important for reverse engineering. The rapid measurement of a free surface and the rapid reconstruction of graphics has been studied. The rectangle grating projection method was applied to the rapid measurement of the free surface of an object. Fourier transforms of a light field in which rectangular gratings were projected on a measured free surface was processed. Phase offset was acquired by computing the modulated raster phase distribution of the measured free surface and a reference plane. As a result, by analysis of the light route of the rectangular grating projection, the relation between phase offset and height of measured free surface was acquired. Sequentially, the height information of the measured object was computed. For rapid reconstruction, a rectangle region of each scatter data point on the parameter plane was constructed. The coordinates of each grating point were computed from the region boundary and the grating space. The measured scattered data were interpolated with a special Hermite algorithm, and the height of each grating point in each functionary field was computed. The new surface with rectangle gridding was formed by the accumulation of several overlapped rectangles. The method was applied to the rapid reverse engineering of an automobile engine cover, and shown to result in great improvement.
An image has directional selection capability with high frequency through wavelet transformation. It is coincident with the visual characteristics of human eyes. The most important visual characteristic in human eyes is the visual covering effect. The embedded Zero-tree Wavelet (EZW) coding method completes the same level coding for a whole image. In an image, important regions (regions of interest) and background regions (indifference regions) are coded through the same levels. On the basis of studying the human visual characteristics, that is, the visual covering effect, this paper employs an image-compressing method with regions of interest, i.e., an algorithm of Embedded Zero-tree Wavelet with Regions of Interest (EZWROI Algorism) to encode the regions of interest and regions of non-interest separately. In this way, the lost important information in the image is much less. It makes full use of channel resource and memory space, and improves the image quality in the regions of interest. Experimental study showed that a resumed image using an EZW_ROI algorithm is better in visual effects than that of EZW on condition of high compression ratio.
In the paper, development on MBE-based SiGe/Si heterojunction bipolar transistors (HBT) is described. The SiGe/Si film used in the present work was grown by SIVA32 molecular beam epitaxy system made in Riber, France. 3 micrometers process technology with poly-silicon emitter was used to develop SiGe HBT devices. The experimental results indicated that both the direct current characteristics and the cutoff frequency of SiGe HBT are satisfactory. The current gain (beta) of HBT devices is 50, when the collector voltage V<SUB>c</SUB> equals 2V and the collector current I<SUB>c</SUB> equals 5 mA. The cutoff frequency f<SUB>T</SUB> equals 5.1 GH<SUB>z</SUB>. And the uniformity of the cutoff frequency of HBT is quite good.