ppxscal/embedding_network huggingface dataset:
A terabit IP switch router using optoelectronic technology
Authors: H. Jonathan Chao, Xiaolei Guo, Cheuk-Hung Lam, Ti-Shiang Wang
Venue: Journal of High Speed Networks (1999)

Terabit IP switch router is a key to the success of next generation Internet (NGI) with its backbone capacity supporting exponentially increasing traffic. The challenges in designing a terabit IP switch router include (1) a large capacity switch fabric providing high speed interconnection for a number of smaller capacity router modules, and (2) a fast arbitration scheme resolving output contention within stringent time constraint while achieving high throughput and low delay. In this paper, an input-output buffered switch architecture with a speedup of two is employed; our simulation results show that it can nearly achieve the theoretic bound in average delay/throughput performance of an output buffered switch. We propose a 256\times 256 multicast optical interconnection network (OIN) based on advanced wavelength division multiplexing (WDM) technology as the switch fabric for terabit IP switch routers. Its component and interconnection complexity, and power budget are evaluated. A novel ping-pong arbitration (PPA) scheme is used to solve the output contention in the OIN. The arbitration time of an N-input switch can be achieved in the order of \log_4\lceil N/2\rceil. For instance, with N=256 the arbitration can be completed in 11 gates delay, less than 5 ns using the current CMOS technology, showing that the PPA scheme can support multiple terabit/s switch capacity.
The role of accounting information system in the sustainability of agricultural development projects in Nigeria
Authors: Taiwo Toluyemi
Venue: Information Technology for Development (1999)

It was noted that there is poor communication of accounting information in the Agricultural Development Projects (ADPs). This creates information gaps among the financial and non-financial managers. The gap is occasioned by ignorance, lack of trust and personality clash among ADPs&rsquo; staff. This hinders effective and efficient gathering and dissemination of accounting information in ADPs. The tripartite funding and controls of ADPs makes their accounting data processing and management different. Accounting information can assist in achieving sustainability of ADPs by providing information to support decision making, assisting in setting and allocating resources to prioritized areas, promoting industrial relations and cost reduction in the ADPs&rsquo; system. The paper also asserted that in establishing and implementing information processing system to fully realise these benefits, accounting information needs to be properly understood and managed. Accounting information requires management in much the same way as any large stock holdings. Hence accounting information should be such that it is uniquely stored, located, retrieved, updated, disseminated and consequently used to make informed decisions.
On Lower Bounds For Covering Codes
Authors: M. C. Bhandari, K. K. P. Chanduka, A. K. Lal
Venue: Designs, Codes and Cryptography (1998)

We study lower bounds on K(n,R), the minimum number of codewords of any binary code of length n such that the Hamming spheres of radius R with center at codewords cover the Hamming space \Fl_2^n. We generalize Honkala&lsquo;s idea to obtain further improvements only by using some simple observations of Zhang&lsquo;s result. This leads to nineteen improvements of the lower bound on K(n,R) within the range of 1 \leq n \leq 33, \; 1 \leq R \leq 10.
The Equations ATX\pm XTA=B
Authors: H. W. Braden
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

We give necessary and sufficient conditions for the matrix equations ATX\pm XTA=B to admit solutions and give their general solution. Because A may be singular, the solution involves the generalized inverse of A. The (-) equation underlies the modern R-matrix approach to completely integrable Hamiltonian systems. This paper provides a new and algorithmic approach to constructing such R-matrices.
Extracting and visualizing semantic structures in retrieval results for browsing
Authors: Katy Börner
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

The paper introduces an approach that organizes retrieval results semantically and displays them spatially for browsing. Latent Semantic Analysis as well as cluster techniques are applied for semantic data analysis. A modified Boltzman algorithm is used to layout documents in a two-dimensional space for interactive exploration. The approach was implemented to visualize retrieval results from two different databases: the Science Citation Index Expanded and theDido Image Bank.
Verification of Safety Properties Using IntegerProgramming: Beyond the State Equation
Authors: Javier Esparza, Stephan Melzer
Venue: Formal Methods in System Design (2000)

The state equation is a verification technique that has been applied&mdash;not always under this name&mdash;to numerous systems modelled as Petri nets or communicating automata. Given a safety property P, the state equation is used to derive a necessary condition for P to hold which can be mechanically checked. The necessary conditions derived from the state equation are known to be of little use for systems communicating by means of shared variables, in the sense that many of these systems satisfy the property but not the conditions. In this paper, we use traps, a well-known notion of net theory, to obtain stronger conditions that can still be efficiently checked. We show that the new conditions significantly extend the range of verifiable systems.
Automated analysis and fine-tuning of timing properties in embedded real-time systems
Authors: David B. Stewart
Venue: ACM SIGSOFT Software Engineering Notes (2000)

An extremely time-consuming task of producing an embedded real-time system is the final analysis and fine-tuning of the system's timing. Existing CASE tools focus on the software specification and design of embedded systems. They provide little, if any, support after the software has been implemented. Even if the developer uses a CASE tool to design their system, it likely does not meet the timing specifications on the first try. This happens because the CASE tool's software design and real-time analysis is based only on estimated data and idealized models. The tools do not take into account practical concerns such as operatin system overhead, interrupt handling, limitations of the programming language or processor, inaccuracies in estimating worst-case execution time of each process, and software errors introduced at the implementation phase by the programmers.Performance monitoring tools allow developers to obtain raw data from the underlying embedded system in real-time. These tools provide most, if not all, of the data needed to pinpoint the problem. Such data, however, is not provided in a symbolic fashion, and thus could be very difficult to understand. The monitors only show what happened during run-time, without correlating those results to the original specifications. Performance monitors also do not perform any analysis on the data that is collected. As a result, there is no means to easily differentiate between parts of the execution that are "normal" versus those parts thathave difficult-to-detect timing errors. Only an expert's eye can quickly spot the differences.We are investigating tools that can help embedded system designers analyze, debug, and fine-tune the timing characteristics of their embedded implementations. Such a tool can have a major impact, by allowing designers whose expertise is in an area other than real-time system analysis, such as communications, controls, or hardware design, to use the tool and obtain valuable information on how to fix their code that is not performing according to specifications.
On the Relationship Between Inventory Costs and Variety Benefits in Retailassortments
Authors: Garrett Van Ryzin, Siddharth Mahajan
Venue: Management Science (1999)

Consider a category of product variants distinguished by some attribute such as color or flavor. A retailer must construct an assortment for the category, i.e., select a subset variants to stock and determine purchase quantities for each offered variant. We analyze this problem using a multinomial logit model to describe the consumer choice process and a newsboy model to represent the retailer's inventory cost. We show that the optimal assortment has a simple structure and provide insights on how various factors affect the optimal level of assortment variety. We also develop a formal definition of the level of fashion in a category using the theory of majorization and examine its implications for category profits.
A new heuristic for rectilinear Steiner trees
Authors: Ion I. Măndoiu, Vijay V. Vazirani, Joseph L. Ganley
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

The minimum rectilinear Steiner tree (RST) problem is one of the fundamental problems in the field of electronic design automation. The problem is NP-hard, and much work has been devoted to designing good heuristics and approximation algorithms; to date, the champion in solution quality among RST heuristics is the Batched Iterated 1-Steiner (BI1S) heuristic of Kahng and Robins. In a recent development, exact RST algorithms have witnessed spectacular progress: The new release of the GeoSteiner code of Warme, Winter, and Zachariasen has average running time comparable to that of the fastest available BI1S implementation, due to Robins. We are thus faced with the paradoxical situation that an exact algorithm for an NP-hard problem is competitive in speed with a state-of-the-art heuristic for the problem.The main contribution of this paper is a new RST heuristic, which has at its core a recent 3/2 approximation algorithm of Rajagopalan and Vazirani for the metric Steiner tree problem on quasi-bipartite graphs&mdash;these are graphs that do not contain edges connecting paris of Steiner vertices. The RV algorithm is built around the linear programming relaxation of a sophisticated integer program formulation, called the bidirected cut relaxation. Our heuristic achieves a good running time by combining an efficient implementation of the RV algorithm with simple, but powerful geometric reductions.Experiments conducted on both random and real VLSI instances show that the new RST heuristic runs significantly faster than Robins' implementation of BI1S and than the GeoSteiner code. Moreover, the new heuristic typically gives higher-quality solutions than BI1S.
An implicit connection graph maze routing algorithm for ECO routing
Authors: Jason Cong, Jie Fang, Kei-Yong Khoo
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

ECO routing is a very important design capability in advanced IC, MCM and PCB designs when additional routings need to be made at the latter stage of the physical design. ECO is difficult in two aspects: first, there are a large number of existing interconnects which become obstacles in the region. A hierarchical approach is not applicable in this situation, and we need to search a large, congested region thoroughly. Second, advances in circuit designs require variable width and variable spacing on interconnects. Thus, a gridless routing algorithm is needed. In this paper, we propose to use an implicit representation of a non-uniform grid graph for gridless maze routing algorithm. A novel slit-tree plus interval-tree data structure is developed, combined with a cache structure, to support efficient queries into the connection graph. Our experiments show that this data structure is very small in memory usage while very fast in answering maze expansion related queries. This make the framework very useful in the ECO type of routing.
Understanding the link between IT project manager skills and project success research in progress
Authors: Nicole Haggerty
Venue: Proceedings of the 2000 ACM SIGCPR conference on Computer personnel research (2000)

Success in information systems project implementations remains an elusive goal for many organizations. One factor contributing to project outcomes is the skills employed by the IT project manager. This study develops a literature based model which seeks to describe the link between IT project managers skills and IT project success. Specifically, IT project managers skills are categorized as business competence, technical competence and relationship competence. The research model proposes that the IT project manager's use of these skills (both level and type of skill) results in different project outcomes. Project success is assessed by way of different perceptual measures as reported by the project manager. Pretest results are favorable and indicate an opportunity to advance our understanding of IT project implementation success factors and the role that IT project management skills play in that outcome. Selection of a pilot site is underway so that phase two of this three phase research program can continue.
High performance adaptive middleware for CORBA-based systems
Authors: E-Kai Shen, Shikharesh Majumdar, Istabrak Abdul-Fatah
Venue: Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing (2000)

Middleware provides inter-operability and transparent location of servers in a heterogeneous distributed environment. A careful design of the middleware software is required however for achieving high performance. This research proposes an adaptive middleware architecture for CORBA-based systems. The adaptive middleware agent that maps an object name to the object reference has two modes of operations. In the handle-driven mode it returns a reference for the requested object to the client that uses this reference to re-send the request for the desired operation to the server whereas in the forwarding mode it forwards the entire client request to the server. The server upon invocation performs the desired operation and returns the results to the client. An adaptive ORB dynamically switches between these two modes depending on the current system load. Using a commercial middleware product called Orbix-MT we have implemented a skeletal performance prototype for the adaptive ORB. Based on measurements made on a network of workstations and a synthetic workload we observe that the adaptive ORB can produce a substantial benefit in performance in comparison to a pure handle-driven or a pure forwarding ORB. Our measurements provide valuable insights into system behavior and performance.
A Process Algebraic Approach to the Schedulability Analysisof Real-Time Systems
Authors: Hanene Ben-Abdallah, Jin-Young Choi, Duncan Clarke, Young Si Kim, Insup Lee, Hong-Liang Xie
Venue: Real-Time Systems (1998)

To engineer reliable real-time systems, it is desirable to detect timing anomalies early in the development process. However, there is little work addressing the problem of accurately predicting timing properties of real-time systems before implementations are developed. This paper describes an approach to the specification and schedulability analysis of real-time systems based on the timed process algebra ACSR-VP, which is an extension of ACSR with value-passing communication and dynamic priorities. Combined with the existing features of ACSR for representing time, synchronization and resource requirements, ACSR-VP is capable of specifying a variety of real-time systems with different scheduling disciplines in a modular fashion. Moreover, we can use VERSA, a toolkit we have developed for ACSR, to perform schedulability analysis on real-time systems specified in ACSR-VP automatically by checking for a certain bisimulation relation.
New methods for speeding up computation of Newton updates in harmonic balance
Authors: M. Gourary, S. Ulyanov, M. Zharov, S. Rusakov
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

A new adaptive approach to solving large dimension harmonic balance (HB) problems is presented. The method is based on adjusting the order of the equation system according to the degree of nonlinearity of each node in the circuit. A block-diagonal preconditioner is used to construct an algorithm for order reducing during the iterative HB process.
High-speed protocol for an all-optical packet switched metropolitan area network
Authors: Mohsen Guizani
Venue: International Journal of Network Management (1997)

An optical metropolitan area network employing packet switching and wavelength division multi-accessing is discussed in this article. Two variations are presented. One employs a preassigned TDM scheme in conjunction with WDM. The other also uses TDM but assigns slots on a packet&hyphen;by&hyphen;packet basis. &copy; 1997 John Wiley Sons, Ltd.
The Explicit-Jump Immersed Interface Method: Finite Difference Methods for PDEs with Piecewise Smooth Solutions
Authors: Andreas Wiegmann, Kenneth P. Bube
Venue: SIAM Journal on Numerical Analysis (2000)

Many boundary value problems (BVPs) or initial BVPs have nonsmooth solutions, with jumps along lower-dimensional interfaces. The explicit-jump immersed interface method (EJIIM) was developed following Li's fast iterative immersed interface method (FIIIM), recognizing that the foundation for the efficient solution of many such problems is a good solver for elliptic BVPs. EJIIM generalizes the class of problems for which FIIIM is applicable. It handles interfaces between constant and variable coefficients and extends the immersed interface method (IIM) to BVPs on irregular domains with Neumann and Dirichlet boundary conditions. Proofs of second order convergence for a one-dimensional (1D) problem with piecewise constant coefficients and for two-dimensional (2D) problems with singular sources are given. Other problems are reduced to the singular sources case, with additional equations determining the source strengths. The advantages of EJIIM are high quality of solutions even on coarse grids and easy adaptation to many problems with complicated geometries, while still maintaining the efficiency of the FIIIM.
Variational Principles and Well-Posedness in Optimization and Calculus of Variations
Authors: Alexander D. Ioffe, Alexander J. Zaslavski
Venue: SIAM Journal on Control and Optimization (2000)

The concluding result of the paper states that variational problems are generically solvable (and even well-posed in a strong sense) without the convexity and growth conditions always present in individual existence theorems. This and some other generic well-posedness theorems are obtained as realizations of a general variational principle extending the variational principle of Deville--Godefroy--Zizler.
On Representations and Integrability of Mathematical Structures in Energy-Conserving Physical Systems
Authors: Morten Dalsmo, Arjan vander Schaft
Venue: SIAM Journal on Control and Optimization (1999)

In the present paper we elaborate on the underlying Hamiltonian structure of interconnected energy-conserving physical systems. It is shown that a power-conserving interconnection of port-controlled generalized Hamiltonian systems leads to an implicit generalized Hamiltonian system, and a power-conserving partial interconnection to an implicit port-controlled Hamiltonian system. The crucial concept is the notion of a (generalized) Dirac structure, defined on the space of energy-variables or on the product of the space of energy-variables and the space of flow-variables in the port-controlled case. Three natural representations of generalized Dirac structures are treated. Necessary and sufficient conditions for closedness (or integrability) of Dirac structures in all three representations are obtained. The theory is applied to implicit port-controlled generalized Hamiltonian systems, and it is shown that the closedness condition for the Dirac structure leads to strong conditions on the input vector fields.
Web proxy caching: the devil is in the details
Authors: Ramón Cáceres, Fred Douglis, Anja Feldmann, Gideon Glass, Michael Rabinovich
Venue: ACM SIGMETRICS Performance Evaluation Review (1998)

Much work in the analysis of proxy caching has focused on high-level metrics such as hit rates, and has approximated actual reference patterns by ignoring exceptional cases such as connection aborts. Several of these low-level details have a strong impact on performance, particularly in heterogeneous bandwidth environments such as modem pools connected to faster networks. Trace-driven simulation of the modem pool of a large ISP suggests that "cookies" dramatically affect the cachability of resources; wasted bandwidth due to aborted connections can more than offset the savings from cached documents; and using a proxy to keep from repeatedly opening new TCP connections can reduce latency more than simply caching data.
New topology designs for the future expansion of the academic network of the Gulf countries
Authors: Rana Ejaz Ahmed, Saad Haj Bakry
Venue: International Journal of Network Management (1997)

This article describes several new design aspects for the future expansion of GULFNET&mdash;the research information network of the Gulf countries. The design methodology developed in the paper takes into account expected traffic growth, technology considerations and user demands. Several scenarios for future GULFNET topologies are presented and evaluated. &copy; 1997 John Wiley Sons, Ltd.
Dynamic ceiling priorities and Ada 95
Authors: Jorge Real, Andy Wellings
Venue: ACM SIGAda Ada Letters (1999)

Ada 95 provides dynamic priorities for tasks but ceiling priorities for protected objects are statically assigned by means of a pragma. The semantic complexity as well as the potential inefficiency of any resulting implementation seem to have been the main objections to including dynamic ceilings in Ada 95. Nevertheless, in frequent scenarios such as multi-moded real-time systems, it is desirable for ceiling priorities to be dynamic, to accommodate the different priority assignments given to tasks in the different modes. This problem is usually worked around by applying the so-called ceiling of ceilings as a static ceiling for all modes, which may result in lower schedulability as extra blocking potentially occurs. In this paper we investigate on how to use a hypothetical Set_Ceiling dynamic operation, without incurring the risk of semantic ambiguities, and how a multi-moded system can benefit from its existence.
Incident Wave Source for Finite-Difference Time-Domain Computation of Electromagnetic Scattering for Objects Embedded in Layered Dispersive Media
Authors: Michael S. Yeung
Venue: Journal of Scientific Computing (1999)

An incident wave source for finite-difference time-domain (FDTD) computation of electromagnetic scattering involving layered dispersive media is described. The method is based on the decomposition of an arbitrary incident wave into its frequency components and computing the corresponding steady-state fields in the FDTD lattice analytically. The wave source can in principle generate an incident wave obeying the dispersion relations and reflection and transmission relations of the FDTD lattice exactly. Numerical results show that, in practical computation, the accuracy of the generated incident wave is limited by FFT aliasing error occurring during waveform synthesis.
A Global Regularization Method for Solving the Finite Min-Max Problem
Authors: O. Barrientos
Venue: Computational Optimization and Applications (1998)

A method is presented for solving the finite nonlinear min-max problem. Quasi-Newton methods are used to approximately solve a sequence of differentiable subproblems where, for each subproblem, the cost function to minimize is a global regularization underestimating the finite maximum function. Every cluster point of the sequence generated is shown to be a stationary point of the min-max problem and therefore, in the convex case, to be a solution of the problem. Moreover, numerical results are given for a large set of test problems which show that the method is efficient in practice.