Robustness or fault-tolerance capability of a network is an important design parameter in both wired and wireless networks. Connectivity of a network is traditionally considered to be the primary metric for evaluation...
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Robustness or fault-tolerance capability of a network is an important design parameter in both wired and wireless networks. Connectivity of a network is traditionally considered to be the primary metric for evaluation of its fault-tolerance capability. However, connectivity κ(G) (for random faults) or region-based connectivity κ R (G) (for spatially correlated or region-based faults, where the faults are confined to a region R) of a network G, does not provide any information about the network state, (i.e., whether the network is connected or not) once the number of faults exceeds κ(G) or κ R (G). If the number of faults exceeds κ(G) or κ R (G), one would like to know, (i) the number of connected components into which G decomposes, (ii) the size of the largest connected component, (iii) the size of the smallest connected component. In this paper, we introduce a set of new metrics that computes these values. We focus on one particular metric called region-based component decomposition number (RBCDN), that measures the number of connected components in which the network decomposes once all the nodes of a region fail. We study the computational complexity of finding RBCDN of a network. In addition, we study the problem of least cost design of a network with a target value of RBCDN. We show that the optimal design problem is NP-complete and present an approximation algorithm with a performance bound of O(log K + 4log n), where n denotes the number of nodes in the graph and K denotes a target value of RBCDN. We evaluate the performance of our algorithm by comparing it with the performance of the optimal solution. Experimental results demonstrate that our algorithm produces near optimal solution in a fraction of time needed to find an optimal solution.
In recent years, elliptic curve cryptography (ECC) has gained widespread exposure and acceptance, and has already been included in many security standards. engineering of ECC is a complex, interdisciplinary research f...
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作者：
ALLEN, DWVINOSKI, WSOVERTON, BADavid W. Allen:is a senior computer scientist at the Machinery Technology Division
Westinghouse Electric Corporation Large Pa. He received the B.A. degree in mathematics from Grinnell College and the M.S. degree in computer science from the University of Pittsburgh. His career with Westinghouse has been divided between assignments in engineering and computer applications. Mr. Allen has published eight technical papers. He received the George Westinghouse Signature A ward of Excellence for his work on the development of the GAGES computer program for designing propeller gages. He is a member of the Association for Computing Machinery (ACM) and the Institute of Electrical and Electronics Engineers (IEEE). Walter S. Vinoski:is a project engineer at the Machinery Technology Division
Westinghouse Electric Corporation Large Pa. and was instrumental in the development of the GAGES computer program. He was awarded the George Westinghouse Signature Award of Excellence for his work on the GAGES program. Mr. Vinoski has six years of marine propulsion system experience specifically with propellers. He earned a B.S. degree in electronics engineering and minored in mathematics at the Ohio Institute of Technology. He is a member of the American Society of Naval Engineers. Bernard A. Overton:graduated from North Carolina Agricultural and Technical State University
Greensboro N.C. in 1958 with a B.S. degree in mechanical engineering. Within two years of joining the U.S. Army Mr. Overton was honorably discharged as a first lieutenant. Mr. Overton worked seven years at Philadelphia Naval Shipyard in the following areas: shafting shafting alignment bearing reactions noise and vibration surveys propellers and propeller blade gage designs. In 1967 Mr. Overton transferred to the Navy Engineering Center. He has worked on main propulsion devices such as water jets propellers (both submarine and surface ship) and propeller blade gages. Mr. Overton was responsible for the establishment of the Naval Inspectors Propeller Certif
One of the most complicated forms encountered in engineering design is that of the marine propeller. The complexities arise from the complicated hydrodynamic surfaces of the propeller blades and the complicated manner...
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One of the most complicated forms encountered in engineering design is that of the marine propeller. The complexities arise from the complicated hydrodynamic surfaces of the propeller blades and the complicated manner in which the blades are oriented with and attached to the hub. Where propeller blades are attached to the hub, the blade shape is blended into the shape of the hub. The geometry of this region is particularly complicated. The shape of the blend is called a fillet, and the blending region is called the fillet region. Sheet metal gages conforming to various blade surface contours are used in the manufacture and inspection of propellers. Five different types of gages define the shape of the propeller in different regions. Fillet gages are such gages that define the shape of propeller blades in the fillet region. This paper describes a new computer-aided method for designing fillet gages. Previous methods of fillet gage design required the designer to follow a complicated layout procedure of determining where a particular unfilleted blade contour intersected the hub. The design of the fillet was then done in another layout procedure. Newly developed numerical procedures incorporated in a computer program have reduced the time required to design a complete set of gages (including fillet gages) from up to several weeks to hours.
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