光缆中光纤余长测试方法探讨

本文提出了一种具有实用意义的既能保证测试重复性,又能准确地测量各种结构光缆中光纤余长的方法。     

A Necessary and Sufficient Condition for the Construction of 2-to-1 Optical FIFO Multiplexers by a Single Crossbar Switch and Fiber Delay Lines

In this paper, we prove a necessary and sufficient condition for the construction of 2-to-1 optical buffered first-in-first-out (FIFO) multiplexers by a single crossbar switch and fiber delay lines. We consider a feedback system consisting of an (M+2)times(M+2) crossbar switch and M fiber delay lines with delays d₁,d₂,...,d_M. These M fiber delay lines are connected from M outputs of the crossbar switch back to M inputs of the switch, leaving two inputs (respectively, two outputs) of the switch for the two inputs (respectively, two outputs) of the 2-to-1 multiplexer. The main contribution of this paper is the formal proof that d₁=1 and d_i les d_i+1 les 2d _i, i=1,2,...,M-1, is a necessary and sufficient condition on the delays d₁,d₂,...,d_M for such a feedback system to be operated as a 2-to-1 FIFO multiplexer with buffer Sigma_i=1 ^Md_i under a simple packet routing policy. Specifically, the routing of a packet is according to a specific decomposition of the packet delay, called the C- transform in this paper. Our result shows that under such a feedback architecture a 2-to-1 FIFO multiplexer can be constructed with M=O(log B), where B is the buffer size. Therefore, our construction improves on a more complicated construction recently proposed by Sarwate and Anantharam that requires M=O(radicB) under the same feedback architecture (we note that their design is more general and works for priority queues)     

A Criterion for the Construction of a Regularization Function in Sparse Component Analysis

With the application of regularization, sparse component analysis (SCA) becomes an effective approximate method for finding the sparsest solution of signal decomposition in an overcomplete dictionary. In this paper, the authors present some conditions on a family of regularization functions indexed by a hyperparameter so that these functions are applicable and can be effectively optimized in SCA. For a given signal, with these conditions it is proven that there exists at least one hyperparameter such that the global minimum of the corresponding regularization function can theoretically lead to the sparsest representation of the signal. Based on these propositions, a general principle is presented for the construction of regularization functions, and several kinds of function families are recommended for the purpose of sparse signal representation. The paper gives a numerical example that indicates that, for a synthesized signal, minimizing the regularization function proposed in this paper provides the correct sparse solution, whereas the method of basis pursuit fails.     

深入贯彻落实党的十六大精神全面开创中国网通集团工作新局面

2003年是我国全面贯彻落实党的十六大精神的第一年,也是中国网络通信集团公司(以下简称"中国网通集团")面临展开全面实质性竞争的第一年.