44084630
Distributed and Fail-Safe Routing Algorithms in Toroidal-Based Metropolitan Area Networks
Abstract A two-dimensional toroidal network is simply a rectangular mesh where opposite nodes on the left and right boundaries are connected to each other and opposite nodes on the upper and lower boundaries are also connected to each other. Examples of toroidal based metropolitan area networks are HR 4 -NET and Manhattan Street Network (MSN). The original routing algorithm for HR 4 -NET proposed by Borgonovo and Cadorin, however, does not direct packets through shortest paths. This paper presents shortest path routing algorithms for HR 4 -NET, which are distributed and fail-safe. These algorithms can also be applied to multiple traffic types. Simple routing rules that use of the regular structure of the network are compared to MSN.
19086803
Transaction management in design databases
Abstract Conventional data base systems are not suitable for handling advanced applications encountered in engineering, such as CAD/CAM, CASE, CAE, and VLSI design. The data bases in such environments, also called design data bases, are characterized by the presence of many complex data objects denoted by a large number of small tables, as opposed to a few large tables encountered in conventional data bases. The transaction model used in tracking data bases for banking, inventory control, and other such applications use view serializability as the correctness criterion. While view serializability is appropriate for tracking data bases, it is unnecessarily restrictive for engineering data bases. We propose a transaction model that is suitable for accessing shared design data based on coserializability. The transaction model supports long-duration transactions with intermediate commit points. In addition to the conventional nested transaction hierarchy, the model allows for cooperation between nested design transactions needed in a design environment.
8543519
Design and Implementation of National Engineering Education Delivery System
45515179
Distributed real-time nested transactions
Abstract We present the concepts of real-time nested transactions and priority propagation for a distributed transaction processing environment. Real-time nested transactions incorporate the deadline requirements in the hierarchical structure of nested transactions. Priority propagation addresses issues related to transaction aborts in real-time nested transaction processing. The notion of priority ceiling has been used to avoid the priority inversion problem. The proposed protocols exhibit freedom from deadlock and have tightly bounded waiting periods. Both of these properties make them very suitable for distributed real-time transaction processing environments.
29262099
Transaction models for design environments
Abstract Design data bases used in the design of engineering artifacts have characteristics quite different from conventional data bases. While conventional data bases have, at any given time, a single correct value for each of object, design data bases, due to the presence of design alternates or versions, have available several correct versions of design objects. However, during a design process, when several design objects are involved, the different versions of each object chosen for the design has to be controlled such that they are compatible or version consistent. This article formalizes the notion of version consistency and proposes two transaction models for design processes, where the notion of version consistency itself is used as a basis for scheduling design transactions. A mechanism for enforcing version control is also presented.
675655
Analysis of Broadcast Delivery in a Videotex System
Videotex is a system which provides users with low-cost real-time access to information. In such a system, user requests are forwarded to a service computer where the desired information is retrieved and sent back to the user. In this study, we investigate the response time behavior of a videotex system where information requested by one user is broadcast to all users. A novel queueing model for broadcast delivery is developed. Using this model, we first obtain an analytic expression for the mean response time, and then we develop an efficient algorithm for its computation. Numerical results illustrating the performance characteristics of broadcast delivery are presented.
10964676
SpecAlign - processing and alignment of mass spectra datasets
SUMMARY
Pre-processing of chromatographic profile or mass spectral data is an important aspect of many types of proteomics and biomarker discovery experiments. Here we present a graphical computational tool, SpecAlign, that enables simultaneous visualization and manipulation of multiple datasets. SpecAlign not only provides all common processing functions, but also uniquely implements an algorithm that enables the complete alignment of each mass spectrum within a loaded dataset. We demonstrate its utility by aligning two datasets each containing six spectra; one set was acquired prior to instrument calibration and the other following calibration.


AVAILABILITY
The software is free of charge and available for download from http://ptcl.chem.ox.ac.uk/~jwong/specalign. Supports Windows operating systems including Windows 9X/NT/2000/XP.
2430654
Watermarking graph partitioning solutions
The authors introduce an Intellectual Property Protection (IPP) technique for graph partitioning which watermarks solutions to the graph partitioning problems so that they carry an author's signature. This technique is completely transparent to the actual computer-aided design tool which does the partitioning and is implemented by preprocessing and postprocessing alone. The authors propose five different schemes for the watermarking of partitioning solutions. The goal is to construct a partitioning solution which not only has a small edge cut, but also encodes the signature of the author. The key idea of all of our schemes is to map the signature into a set of constraints and then satisfy a disproportionate number of these constraints. Four of our schemes are based upon the idea of encouraging groups of vertices to be in the same partition. The fifth is based upon the encouragement of certain edges to be cut by the partitioning. The fifth scheme shows superior performances on all of the cases which we tested, including both two-way and multiway partitioning. The watermarking scheme produces solutions that have very low-quality degradation levels, yet carry signatures that are convincingly unambiguous, extremely unlikely to be present by coincidence and difficult to detect or remove without completely resolving the partitioning problem.
17359298
Queueing Network Modeling of Computer Communication Networks
The application of queueing network models to the performance analysis of messageswitched (or packet-switched) commumcatmn networks m surveyed. The main topics covered are the analysis of end-to-end delay and the analysis of buffer management schemes. A brief discussmn on flow control is also included. A queueing network model is developed for a simple user-resource network. The mean response time of a host computer m this network is illustrated by a numerical example.
21841074
Delay Analysis of Broadcast Routing in Packet-Switching Networks
Broadcast addressing is the capability to send a packet from a source node to all other nodes in the network. Store-and-forward, packet-switching networks are not inherently designed to carry broadcast packets, and broadcasting has to be implemented by some sort of routing algorithm. In this paper, the source based forwarding algorithm is considered. With this algorithm, a spanning tree is defined for each node, and broadcast packets are sent along the branches of these trees. Approximation methods are presented to obtain a lower bound and estimates of the mean broadcast time. The accuracy of these methods is evaluated by comparison with simulation.