We present the theoretical results on using the spontaneous emission which is induced from a two-level atom embedded in a photonic crystal with two bands and one forbidden gap. It is shown that the emission field from the atom is composed of two parts, one is a localized field, which always exists, and the other is one or two propagating modes. The emission of the propagating mode depends on the gap size and the relative position of the upper-level of the atom with respect to the edges of the two bands. The propagating modes have a sudden jump from zero to a certain value when the gap or the related position of the upper level changes. This jump can be used to design an active optical two-channel or four-channel switch. Due to the localized field being within a few dozen atoms, the switch can be designed in a few micrometers.

The loosely-coupled reconfigurable computing model includes the host microprocessor in conjunction with an external stand-alone reconfigurable hardware which takes advantage of low cost in technology and development time. It can work as a fast emulation approach to study reconfigurable computing prototype system. One of the key features of such emulation system is the ability to perform the communication. In this paper, we proposed a high speed hardware channel with direct memory access(DMA) transaction method based on Xilinx ML555 development kit and PCI-express(peripheral component interconnection express) endpoint block IP. Experiments show that both read and write transaction speed in this design meet the theoretical maximum speed.

In company with medical instruments ' development, the corresponding software plays more and more role in the application. And medical image processing software has become an important component of the medical ultrasonic instruments. Image segmentation plays an important role in both qualitative and quantitative analysis of medical ultrasound images. But state-of-arts methods in the aspect of segmentation can not get satisfactory results. We propose an intelligent image segmentation method for medical ultrasonic images. The algorithm improved active contour model with relevance vector machine, where the advantages of supervised learning classification and the global region distribution information can be exploited to enhance the performance. In order to improve the segmentation speed and get precise initial contour, relevance vector machine also is used to obtain initial contour firstly. A large amount of experimental results have proved that our method outperforms many state-of-arts methods in the aspect of segmentation, and the method can be used in ultrasonic instruments effectively.