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91.
翟俊祥 《西安建筑科技大学学报(自然科学版)》1992,(4)
本文指出目前组合逻辑电路分析方法的不足,提出了一种新的方法——条件通路法,使组合电路的逆向分析得以容易实现,从而完善了组合逻辑电路的分析方法。 相似文献
92.
In this paper we study the classical problem of finding disjoint paths in
graphs. This problem has been studied by a number of authors both for specific
graphs and general classes of graphs. Whereas for specific graphs many
(almost) matching upper and lower bounds are known for the competitiveness of
on-line algorithms, not much is known about how well on-line algorithms can
perform in the general setting. The best results obtained so far use the
expansion of a network to measure the algorithms performance. We use a
different parameter called the routing number that, as we will show, allows
more precise results than the expansion. It enables us to prove tight upper and
lower bounds for deterministic on-line algorithms. The upper bound is obtained
by surprisingly simple greedy-like algorithms. Interestingly, our upper bound
on the competitive ratio is even better than the best previous approximation
ratio for off-line algorithms. Furthermore, we introduce a refined variant of
the routing number and show that this variant allows us, for some classes of
graphs, to construct on-line algorithms with a competitive ratio significantly
below the best possible upper bound that could be obtained using the routing
number or the expansion of a network only. We also show that our on-line
algorithms can be transformed into efficient algorithms for the more general
unsplittable flow problem. 相似文献
93.
A VPN is an optical virtual private network (oVPN) built of wavelength paths within a multihop wavelength routing (WR) dense wavelength division multiplexing (DWDM) network. An efficient and general graph-theoretic model (the wavelength-graph (WG)) has been proposed along with an integer linear programming (ILP) formulation of setting up VPNs with given traffic requirements over a given WR-DWDM network with two protection scenarios. Here, we have exploited the advantages of traffic grooming, i.e., numerous traffic streams of a VPN can share a wavelength path. We have also generalized the model for setting up VPNs over a WR-DWDM system where multiple VPNs can share a single wavelength path. The objective of the optimization is in all cases to reduce resource usage at upper (electrical) layers (i.e., to reduce the load of the virtual routers), subject to constrained amount of capacity of each wavelength channel and limited number of wavelengths. Here, we propose and compare three basic methods for configuring oVPNs and investigate various parameter settings. 相似文献
94.
The hierarchical hypercube network is suitable for massively parallel systems. One of its appealing properties is the low number of connections per processor, which can facilitate the VLSI design and fabrication. Other alluring features include symmetry and logarithmic diameter, which can derive easy and fast algorithms for communication. In this paper, a maximal number of node-disjoint paths are constructed between every two distinct nodes of the hierarchical hypercube network. Their maximal length is not greater than max{2m+1+2m+1,2m+1+m+4}, where 2m+1 is the diameter. The effectiveness of node-disjoint paths is further verified by experiments. 相似文献
95.
Reliability of a computer network in case capacity weight varying with arcs, nodes and types of commodity 总被引:1,自引:0,他引:1
The computer network can be modeled as a capacitated-flow network. This paper concentrates on a two-commodity capacitated-flow network with three characters: (1) nodes as well as arcs have multiple possible capacities and may fail, (2) each component (arc/node) has both capacity and cost attributes; and (3) the capacity weight varies with arcs, nodes and types of commodity (or named file). We study the possibility that a given quantity of two types of files can be transmitted through this network simultaneously under the budget constraint. Such a possibility is named the system reliability which is a performance index to measure the quality level of supply demand systems such as computer, telecommunication, electric-power transmission and transportation systems. The approach of minimal paths is applied to describe the relationship among flow assignments and capacity vectors. A simple algorithm in terms of minimal paths is proposed to evaluate the system reliability. 相似文献
96.
Abdelhamid Mellouk Saïd Hoceïni Yacine Amirat 《International Journal of Communication Systems》2007,20(10):1113-1130
In this paper, we propose two adaptive routing algorithms based on reinforcement learning. In the first algorithm, we have used a neural network to approximate the reinforcement signal, allowing the learner to take into account various parameters such as local queue size, for distance estimation. Moreover, each router uses an online learning module to optimize the path in terms of average packet delivery time, by taking into account the waiting queue states of neighbouring routers. In the second algorithm, the exploration of paths is limited to N‐best non‐loop paths in terms of hops number (number of routers in a path), leading to a substantial reduction of convergence time. The performances of the proposed algorithms are evaluated experimentally with OPNET simulator for different levels of traffic's load and compared with standard shortest‐path and Q‐routing algorithms. Our approach proves superior to classical algorithms and is able to route efficiently even when the network load varies in an irregular manner. We also tested our approach on a large network topology to proof its scalability and adaptability. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
97.
98.
A recurrent formula and an ordinary formula are proposed for the number of Hamiltonian paths on special digraphs generated by a chain metric on n-permutations. 相似文献
99.
100.
K Lakshminarayana 《Sadhana》1997,22(3):383-391
Developments in mechanical power transmission have hinged around better materials and processes, new design ideas and effective
new application of enduring scientific design principles and ideas. The current presentation aims at showing how deliberate
measures to optimize load distribution have increased the compactness and capabilities of present day gear transmissions.
Exploitation of parallel power paths, packing of gears in annular spaces and the effective use of epicyclic action by reducing
the number of gear meshes and substituting rolling friction are explained.
Deceased 相似文献