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This paper presents fast algorithms for the type-II and -III discrete cosine transforms of composite sequence length. In particular, a radix-q algorithm, where q is an odd integer, is derived for uniform or mixed radix decomposition of the discrete cosine transform. By combining the radix-q and radix-2 algorithms, a general decomposition method for any composite length is developed. Reduction of computational complexity can be achieved for many sequence lengths compared with that needed by the well-known radix-2 algorithm. Furthermore, both the proposed and Chan and Siu's (1993) mixed radix algorithms achieve the same computational complexity for N=3*2p and 9*2P. However, our algorithm uses a simpler decomposition approach and provides a wider range of choices of sequence lengths 相似文献
53.
Based on a decimation-in-time decomposition, a fast split-radix algorithm for the 2D discrete Hartley transform is presented. Compared to other reported algorithms, the proposed algorithm achieves substantial savings on the number of operations and provides a wider choice of transform sizes 相似文献
54.
分析了OSI参考模型和B-ISDN协议参考模型之间的关系,为B-ISDN与以OSI为标准的数据网的互联打下了基础。 相似文献
55.
J.P. Zhang D.Y. Chu S.L. Wu W.G. Bi R.C. Tiberio R.M. Joseph A. Taflove C.W. Tu S.T. Ho 《Photonics Technology Letters, IEEE》1996,8(4):491-493
A strongly-guided one-dimensional (1-D) waveguide called a photonic wire has high spontaneous emission coupling efficiency, enabling one to realize low-threshold lasers. Combined with the use of 1-D photonic bandgap structures consisting of arrays of holes etched within the photonic wire, novel microcavity lasers can be realized. We report the nanofabrication of a photonic bandgap structure for 1.5 /spl mu/m wavelength along a InGaAsP photonic wire, and discuss numerical simulations for its electrodynamics. 相似文献
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J.P. Zhang D.Y. Chu S.L. Wu W.G. Bi R.C. Tiberio C.W. Tu S.T. Ho 《Photonics Technology Letters, IEEE》1996,8(8):968-970
We have obtained directional light output from a recently realized InGaAsP photonic-wire microcavity ring lasers. The output was achieved by fabricating a 0.45-/spl mu/m-wide U-shape waveguide next to a 10-/spl mu/m diameter microcavity ring laser. The laser has a threshold pump power of around 124 /spl mu/W when optically pumped at 514 nm. It is comparable to the former structure without output coupling. The output coupling efficiency can be controlled carefully by choosing the spacing between the laser cavity and the waveguide. 相似文献
58.
本文应用线性近似规化方法对汽油机的工作过程进行优化。分别以汽油机的燃油消耗率、氧化氮排放浓度和爆震指数作为目标函数进行优化计算.避免了单目标优化模型的局限性。初始点是通过网格法寻优获得,然后用修正的单纯形法求解。优化计算使汽油机的性能指标得到提高,表明这种方法可以为综合评价汽油机的工作过程提供理论依据。 相似文献
59.
Y.F. Li D. Bi 《Mechatronics, IEEE/ASME Transactions on》2003,8(4):476-482
Realistic dynamics models are important for haptic display for virtual reality systems. Such dynamic models are desirably obtained via experimental identification. However, traditional dynamics identification methods normally require large sized training data sets, which maybe difficult to meet in many practical applications. To obtain the dynamics models, we present, in this paper, an identification method using support vector machines regression algorithm which is more effective than traditional methods for sparse training data. This method can be used as a generic learning machine or as a special learning technique that can make full use of the available knowledge about the dynamics structure. The experimental results show the application of our method for identifying friction models for haptic display. 相似文献
60.