Abdella Battou

On M-strong fuzzy graphs

The cartesian product and disjoint sum of graphs play a prominent role and have numerous interesting algebraic properties. In this note, we consider operations on fuzzy graphs under which M-strong property is preserved. If G1 and G2 are M-strong fuzzy graphs then we prove that G1 × G2, G1 [G2] and G1 + G2 are also M-strong but G1 ∪ G2 need not be M-strong. If G1 × G2 is M-strong then we show that at least one factor must be M-strong. We show that the product of a M-strong fuzzy graph G1 with a non-M-strong fuzzy graph G2 remains M-strong if and only if G2 satisfies special condition. For any fuzzy graph G, Gcc is the smallest M-strong fuzzy graph that contains G and G = Gcc if and only if G is M-strong. We further show that M-strong fuzzy graph G is a fuzzy tree if and only if the support(G) is a tree.

An application of fuzzy relations to image enhancement

Abstract When images are converted from one form to another they are subject to nonlinear transformations that reduce the output quality. This paper presents an image enhancement technique based on fuzzy relations that can be applied to improve the appearance of these images. A grey-scale image I with M rows and N columns is viewed as a weighted relation from a set X with M elements into a set Y with N elements with g ( x , y ) representing the grey-value at location ( x , y ) in I . An appropriate choice of two thresholds corresponding to pixels close to black and white pixels is made which partitions the image into crisp and fuzzy pixels. The fuzzy pixels correspond to pixels which are either black or white with a certain degree of membership between 0 and 1. The original image is transformed into an enhanced image by forming its dual complement. This is achieved by first constructing fuzzy sets σ x and σ y on X and Y respectively and applying these fuzzy sets to manipulate only the fuzzy pixels in I . After the entire transformation, the maximally fuzzy pixels, that is, pixels with membership value equal to 1 2 , get enhanced towards either black or white, depending on the neighborhood pixels of the segment to which they belong. The performance of the proposed technique is demonstrated on several images. Enhanced images obtained using other techniques are also presented for comparison.

Two Approaches for Aggregation of Peer Group Topology in Hierarchical PNNI Networks

ABSTRACTWe propose two methods for aggregation of peer group topology in hierarchical ATM networks. Both proposed aggregation methods transform a given peer group into a star graph representation. Our first approach optimally preserves, in a least square sense, the original costs of routing through the peer group. Our second approach assigns a weighted vector to the nucleus of the Logical Group Node, which quantifies the error in the compact representation. The two schemes are dual, in the sense that the first is best suited for peergroups where traffic patterns are unpredictable, and the second is suited for peergroups where traffic patterns can be characterized. Both the proposed schemes are practical: For peer groups with nodes V, links E, and n border nodes B ⊂ V, the approaches run in O(n|V|log|V| + n|E|+ poly(n)) time. The size of the final representation is small (linear in the number of border nodes) and can be computed efficiently. The scalability of the proposed algorithms makes them well-suited...

CASiNO: component architecture for simulating network objects

We describe the Component Architecture for Simulating Network Objects (CASiNO) useful for the implementation of communication protocol stacks and network simulators. This framework implements a rich, modular coarse‐grained dataflow architecture, with an interface to a reactor kernel that manages the applications handlers for asynchronous I/O, real timers and custom interrupts. These features enable developers to write applications that are driven by both data flow and asynchronous event delivery, while allowing them to keep these two functionalities distinct. We provide an example program and expository comments on the program to illustrate the use of the CASiNO framework. Published in 2002 by John Wiley & Sons, Ltd.

The effect of wavelength advertisement on the performance of an optical routing protocol

This paper investigates the efficiency of wavelength selection in an optical network when it is conducted without knowledge of wavelength utilization, and compares it to the case when switches exchange wavelength availability through a routing protocol such as OSPR. We describe a series of experiments to determine the effect of wavelength advertisement on connection blocking probability in heterogeneous networks consisting of both wavelength converter and nonconverter switches. Based on these experiments, we describe some consequences of advertising wavelength availability, and quantify when it is advantageous to advertise wavelength availability within the routing protocol.

Introducing PRouST: the PNNI routing and simulation toolkit

Despite the increased availability of affordable ATM hardware, the scientific research community has often found it difficult to engage in much needed basic research in the areas of ATM protocol design and network performance optimization. We believe that one major cause for this has been the absence of affordable, publicly available source-level implementations of the ATM switch protocol stack. The PNNI routing and simulation toolkit (PRouST) attempts to remedy this. PRouST is a freely distributed, extensible environment for research and development in ATM switch signaling and routing. PRouST includes a complete source-level release of the ATM switch PNNI protocol stack, conformant to version 1.0 of the ATM Forum specification. It is our hope that PRouST will serve as the starting point for bold new initiatives in research and development for ATM technologies. We describe the design of PRouST and the features it supports.

TRON: the toolkit for routing in optical networks

The toolkit for routing in optical networks (TRON) is a freely available library developed to facilitate research experiments on OSPF-based routing protocols for optical networks. Currently, TRON supports the lightwave-OSPF routing protocol, which is our adaptation of the optical extensions to OSPF proposed in the Internet drafts of Kompella et al and Wang et al. TRON is implemented in C++ using the component architecture for simulating network objects (CASiNO). TRON software can be used in either simulation or emulation mode. In this paper, we describe lightwave-OSPF and the architecture of the TRON software.

Optical Switching: Networking and Computing for Multimedia Systems

Optical networking capabilities for the next-generation Internet analysis of multimedia access protocols for shared medium networks the design and performance of a lightwave data storage network using computer analysis and simulation routed wavelength WDM networks the optical network control plane routing and path establishment for point-to-point and point-to-multipoint communications over WDM networks routing in multihop optical WDM networks with limited wavelength conversion optical ATM switch architectures scalable electro-optical clos switch arhitectures parallel free-space optical interconnection.

SEAN for Modeling and Simulating ATM Signaling

SEAN (signaling entity for ATM networks) is freely distributed, object-oriented, extensible software for research and development in host ATM signaling. SEAN software is object-oriented and can be used for simulation, experimentation, and operation. SEAN includes a complete source-level release of the host native ATM protocol stack and implements the ATM User Network Interface, compliant to the ITU Q.2931 specification for point-to-point calls, the ITU Q.2971 extension for point-to-multipoint calls, and the ATM Forum extension UNI-4.0 for leaf-initiated join calls. SEAN also includes software that models and simulates an ATM switch with an arbitrary number of ports performing the signaling functions. SEAN provides APIs to the programmers writing application programs that require ATM signaling. Developers can easily modify and extend SEAN, using the framework library released together.

Introducing SEAN: Signaling Entity for ATM networks

SEAN is freely distributed, object-oriented, extensible software for research and development in host ATM signaling. SEAN includes a complete source-level release of the host native ATM protocol stack, and implements the ATM user network interface, compliant to the ITU Q.2931 specification for point-to-point calls, the ITU Q.2971 extension for point-to-multipoint calls, and the ATM Forum extension UNI-4.0 for leaf initiated join calls, SEAN provides APIs to the programmers writing application programs that require ATM signaling. Developers can easily modify and extend SEAN, using the framework library released together. This paper describes essential parts of SEANs architecture and guides the users and protocol developers.