ppxscal/embedding_network huggingface dataset:
The Local Discontinuous Galerkin Method for Time-Dependent Convection-Diffusion Systems
Authors: Bernardo Cockburn, Chi-Wang Shu
Venue: SIAM Journal on Numerical Analysis (1998)

In this paper, we study the local discontinuous Galerkin (LDG) methods for nonlinear, time-dependent convection-diffusion systems. These methods are an extension of the Runge--Kutta discontinuous Galerkin (RKDG) methods for purely hyperbolic systems to convection-diffusion systems and share with those methods their high parallelizability, high-order formal accuracy, and easy handling of complicated geometries for convection-dominated problems. It is proven that for scalar equations, the LDG methods are L2-stable in the nonlinear case. Moreover, in the linear case, it is shown that if polynomials of degree k are used, the methods are kth order accurate for general triangulations; although this order of convergence is suboptimal, it is sharp for the LDG methods. Preliminary numerical examples displaying the performance of the method are shown.
QoS provided by the IEEE 802.11 wireless LAN to advanced data applications: a simulation analysis
Authors: G. Anastasi, L. Lenzini
Venue: Wireless Networks (2000)

IEEE 802.11 is a Media Access Control &lpar;MAC&rpar; protocol which has been standardized by IEEE for Wireless Local Area Networks &lpar;WLANs&rpar;. The IEEE 802.11 MAC protocol offers two types of services to its users&colon; synchronous and asynchronous. This paper presents an in&dash;depth analysis, by simulation, of the asynchronous part alone. The analysis is performed by considering station data traffic patterns &lpar;hereafter advanced data traffic&rpar; which have a very similar shape to traffic generated by WWW applications. We carried out the simulation by taking into consideration two classes of scenarios&colon; balanced and unbalanced. In the former class each station has the same offered load while in the latter class a specific station is more loaded than the others. Our conclusion is that the IEEE 802.11 MAC protocol performs satisfactorily for both classes of scenarios, although performance measures with advanced traffic are worse than the corresponding performance measures with Poissonian traffic. Furthermore, we broadened our analysis to include higher medium capacities than those planned &lpar;i.e., 1 and 2 Mbit/sec&rpar; up to 10 Mbit/sec. This part of the analysis shows that the IEEE 802.11 MAC protocol is not adequate to work at speeds planned for the forthcoming ATM Wireless LAN.
On the efficient implementation of fair non-repudiation
Authors: Cheng-Hwee You, Jianying Zhou, Kwok-Yan Lam
Venue: ACM SIGCOMM Computer Communication Review (1998)

Due to the explosive growth of electronic businesses carried on the Internet, non-repudiation services turn out to be increasingly important. Non-repudiation services protect the transacting parties against any false denial that a particular event or action has taken place, in which evidence will be generated, collected and maintained to enable the settlement of disputes. Several fair non-repudiation protocols have been proposed, which support non-repudiation of origin and non-repudiation of receipt while neither the originator nor the recipient can gain an advantage by quitting prematurely or otherwise misbehaving during a transaction. However, a critical issue on how to maintain the validity of non-repudiation evidence efficiently during and after a transaction was not considered. This paper uses the idea of evidence chaining to address such a problem.
A special learning environment for repeat students
Authors: Judy Sheard, Dianne Hagan
Venue: Proceedings of the 4th annual SIGCSE/SIGCUE ITiCSE conference on Innovation and technology in computer science education (1999)

In 1997, surveys of a group of introductory programming students, in a class with a predominance of repeat students (i.e., students who had previously failed the subject), provided an opportunity to establish a profile of the weakest students. These students were the "alienated" ones who had not wanted to do this course in the first place, had little motivation to learn programming, and were characterised by poor class attendance and low work output. In 1998 a new learning environment, tailored to these students' special needs, was implemented to encourage them to achieve success. Improvement was observed in many aspects of the learning behaviour of these students.
Interactive Orthogonal Graph Drawing
Authors: Achilleas Papakostas, Ioannis G. Tollis
Venue: IEEE Transactions on Computers (1998)

Many applications require human interaction during the design process. The user is given the ability to alter the graph as the design progresses. Interactive Graph Drawing allows the user to dynamically interact with the drawing of a graph. In this paper, we discuss features that are essential for an interactive orthogonal graph drawing system. We also describe some possible interactive drawing scenarios, present results on two of them, and compare their performance.
Fast simulation of networks of queues with effective and decoupling bandwidths
Authors: Matthias Falkner, Michael Devetsikiotis, Ioannis Lambadaris
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1999)

A significant difficulty when using Monte Carlo simulation for the performance analysis of communication networks is the long runtime required to obtain accurate statistical estimates. Under the proper conditions, importance sampling (IS) is a technique that can speed up simulations involving rare events in network (queuing) systems. Large speed-up factors in simulation runtime can be obtained with IS if the modification or bias of the underlying probability measures of certain random processes is carefully chosen. Fast simulation methods based on large deviation theory (LTD) have been successfully applied in many cases.In this paper, we set up an IS-based simulation of various elementary network topologies. These configurations are frequenly encountered in broadband ATM-based network components such as switches and multiplexers. Our objective in this study is to obtain the optimal or near-optimal biasing parameter values of the arrival processes for the importance sampling simulation. For this purpose we appropriately apply a technique presented by Chang et al. for certain portions of the networks (intree) while we develop a new algorithm, inspired by the work of De Veciana et al. on decoupling bandwidths, for the non-intree portion of the network.
Towards an Intelligent Tutoring System Architecturethat Supports Remedial Tutoring
Authors: Julika Siemer, Marios C. Angelides
Venue: Artificial Intelligence Review (1998)

For successful teaching to take place an intelligent tutoring system has to be able to cope with any student errors that may occur during a tutoring interaction. Remedial tutoring is increasingly viewed as a central part of the overall tutoring process, and recent research calls for adaptive remedial tutoring. This paper discusses the issues of remedial tutoring that have been proposed or implemented to support efficient remedial tutoring. These issues serve to uncover any underlying principles of remediation that govern remedial tutoring with intelligent tutoring systems. In order to incorporate these principles of remediation into intelligent tutoring systems development processes this paper continues with the development of a model that can be employed in the development of an intelligent tutoring system that is capable of offering remedial tutoring according to these principles. This model is a formalisation of remedial interventions with intelligent tutoring systems. To demonstrate how the model can be employed in developing an intelligent tutoring system, INTUITION, the implementation of an existing business simulation game, has been developed. This paper concludes with an illustration of how the model for remedial operations provides for remedial tutoring within INTUITION. The evaluation of INTUITION shows that the model for remedial operations is a useful method for providing efficient remedial tutoring.
The Analysis of Under Water Vehicle Non-Stationary AcousticTransient Signals Using a New Fast Algorithm for ConstructingPositive Time-Frequency Distributions
Authors: Dale Groutage
Venue: Multidimensional Systems and Signal Processing (1998)

It is well know that under water vehicles emit many types of acoustic signals, including stationary as well as non-stationary. The non-stationary transient signals are receiving considerable attention, especially from the standpoint of detection and tracking of under water vehicles. Thus, modern methods for processing these non-stationary acoustic transient signals are required. This paper presents a very powerful method for analyzing acoustic transient signals, the positive time-frequency distribution. A fast algorithm that implements the minimum cross-entropy positive time-frequency distribution makes practical the processing of &rsquo;&rsquo;real world data&lsquo;&lsquo;, like under water vehicle acoustic transient signals. An example of such a signal is presented, which is a generic acoustic transient signal from a under water vehicle. The signal is only representative, as it is normalized in time, in frequency, and in amplitude. The positive time-frequency distribution constructed for this generic transient signal is contrasted with the one-third octave method, which is currently the primary method being used by the under water vehicle community to analyze under water vehicle transients. The positive distribution is also contrasted with broad band and narrow band spectrograms.
Providing Security and Interoperation of HeterogeneousSystems
Authors: Steven Dawson, Shelly Qian, Pierangela Samarati
Venue: Distributed and Parallel Databases (2000)

Interoperation and information sharing among databases independently developed and maintained by different organizations is today a pressing need, if not a practice. Governmental, military, financial, medical, and private institutions are more and more required to become part of a distributed infrastructure and selectively share their data with other organizations. This sharing process inevitably opens the local system to new vulnerabilities and enlarges the space of possible threats to the data and resources it maintains. As a complicating factor, in general, data sources are heterogeneous both in the data models they adopt and in the security models by which protection requirements are stated. We present a modeling and architectural solution to the problem of providing interoperation while preserving autonomy and security of the local sources based on the use of wrappers and a mediator. A wrapper associated with each source provides a uniform data interface and a mapping between the source's security lattice and other lattices. The mediator processes global access requests by interfacing applications and data sources. The combination of wrappers and mediator thus provides a uniform data model interface and allows the mapping between restrictions stated by the different security policies. We describe the practical application of these ideas to the problem of trusted interoperation of health care databases, targeted to enforcing security in distributed applications referring to independent heterogeneous sources protected by mandatory policy restrictions. We describe the architecture and operation of the system developed, and describe the tasks of the different components.
Requirements engineering in the year 00: a research perspective
Authors: Axel van Lamsweerde
Venue: Proceedings of the 22nd international conference on Software engineering (2000)

Requirements engineering (RE) is concerned with the identification of the goals to be achieved by the envisioned system, the operationalization of such goals into services and constraints, and the assignment of responsibilities for the resulting requirements to agents such as humans, devices, and software. The processes involved in RE include domain analysis, elicitation, specification, assessment, negotiation, documentation, and evolution. Getting high-quality requirements is difficult and critical. Recent surveys have confirmed the growing recognition of RE as an area of utmost importance in software engineering research and practice.The paper presents a brief history of the main concepts and techniques developed to date to support the RE task, with a special focus on modeling as a common denominator to all RE processes. The initial description of a complex safety-critical system is used to illustrate a number of current research trends in RE-specific areas such as goal-oriented requirements elaboration, conflict management, and the handling of abnormal agent behaviors. Opportunities for goal-based architecture derivation are also discussed together with research directions to let the field move towards more disciplined habits.
Interactive control for physically-based animation
Authors: Joseph Laszlo, Michiel van de Panne, Eugene Fiume
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

We propose the use of interactive, user-in-the-loop techniques for controlling physically-based animated characters. With a suitably designed interface, the continuous and discrete input actions afforded by a standard mouse and keyboard allow for the creation of a broad range of motions. We apply our techniques to interactively control planar dynamic simulations of a bounding cat, a gymnastic desk lamp, and a human character capable of walking, running, climbing, and various gymnastic behaviors. The interactive control techniques allows a performer's intuition and knowledge about motion planning to be readily exploited. Video games are the current target application of this work.
BIFEST: a built-in intermediate fault effect sensing and test generation system for CMOS bridging faults
Authors: Kuen-Jong Lee, Jing-Jou Tang, Tsung-Chu Huang
Venue: ACM Transactions on Design Automation of Electronic Systems (TODAES) (1999)

This paper presents BIFEST, an ATPG system that employs the built-in intermediate voltage test technique in an efficient ATPG process to deal with CMOS bridging faults. Fast and accurate calculations of the intermediate bridging voltages and the variant threshold tolerance margins on a resistive bridging fault model are presented. A PODEM-like, PPSFP-based ATPG process is developed to generate test patterns for faults that are conventionally logic-testable. The remaining faults are then dealt with by special circuits, called built-in intermediate voltage sensors (BIVSs). By this methodology, almost the same fault coverage as that employing IDDQ testing can be achieved with only logic monitoring required.
Efficiency of Characterizing Ellipses and Ellipsoids by Discrete Moments
Authors: Jovisa Zunic, Natasha Sladoje
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

In this paper, our studies are focused on ellipses and problems related to their representation and reconstruction from the data resulting from their digitization. The main result of the paper is that a finite number of discrete moments, corresponded to digital ellipses, is in one-to-one correspondence with digital ellipses, which enables coding of digital ellipses with an asymptotically optimal amount of memory. In addition, the problem of reconstruction, based on the same parameters, is considered. Since the digitization of real shapes causes an inherent loss of information about the original objects, the precision of the original shape estimation from the corresponding digital data is limited. We derive a sharp upper bound for the errors in reconstruction of the center position and half-axes of the ellipse, in function of the applied picture resolution (i.e., the number of pixels per unit). An extension of these results to the $3D$ case is also given.
Prediction of future world wide web traffic characteristics for capacity planning
Authors: Kenneth J. Christensen, Nandini J. Javagal
Venue: International Journal of Network Management (1997)

To plan for future network capacity requires an understanding of traffic. This article presents a traffic characterization and performance evaluation of future WWW protocols. &copy; 1997 John Wiley & Sons, Ltd.
Completion time multiple branch prediction for enhancing trace cache performance
Authors: Ryan Rakvic, Bryan Black, John Paul Shen
Venue: Proceedings of the 27th annual international symposium on Computer architecture (2000)

The need for multiple branch prediction is inherent to wide instruction fetching. This paper presents a completion time multiple branch predictor called the Tree-based Multiple Branch Predictor (TMP) that builds on previous single branch prediction techniques. It employs a tree structure of branch predictors, or tree-node predictors, and achieves accurate multiple branch prediction by leveraging the high accuracies of the individual branch predictors. A highly-efficient TMP design uses the 2-bit saturating counters for the tree-node predictors. To achieve higher prediction rate, the TMP employs two-level schemes for the tree-node predictors resulting in a three-level TMP design. Placing the TMP at completion time reduces the critical latency in the front-end of the pipeline; the resultant longer update latency does not significantly impact the overall performance. In this paper the TMP is applied to a trace cache design and shown to be very effective in increasing its performance. Results: A realistic-size TMP (72KB) can predict 1, 2, 3, and 4 consecutive blocks with compounded prediction accuracies of 96%, 93%, 87%, and 82%, respectively. The block-based trace cache with this TMP achieves 4.75 IPC for SPECint95 on an idealized machine, which is a 20% performance improvement over the original design [1]. This improved performance is 8% above that of a conventional I-cache design with perfect single branch prediction.
On Optimal Banded Preconditioners for the Five-Point Laplacian
Authors: Zhanye Tong, Ahmed Sameh
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

We prove the following theorem, which includes a conjecture by Greenbaum and Rodrigue [[ BIT, 29 (1989), pp. 610--634] as a special case: Let Ah be the five-point Laplace matrix on a unit square for grid size h, and let Mh be any symmetric positive definite preconditioner for Ah with half bandwidth k=O(1). Then the condition number $\kappa(M_h^{-{1\over 2}}A_hM_h^{-{1\over 2}})$ satisfies $\kappa(M_h^{-{1\over 2}}A_hM_h^{-{1\over 2}}) = O(h^{-2}).
On Bivariate Hermite Interpolation with Minimal Degree Polynomials
Authors: Mariano Gasca, Thomas Sauer
Venue: SIAM Journal on Numerical Analysis (2000)

A Newton-type approach is used to deal with bivariate polynomial Hermite interpolation problems when the data are distributed in the intersections of two families of straight lines, as a generalization of regular grids. The interpolation operator is degree-reducing and the interpolation space is a minimal degree space. Integral remainder formulas are given for the Lagrange case, then extended to the Hermite case, and finally used to obtain error estimates.
Hole-Cutting for Three-Dimensional Overlapping Grids
Authors: N. Anders Petersson
Venue: SIAM Journal on Scientific Computing (1999)

A hole-cutting technique for assembling overlapping grid systems for solving partial differential equations is presented. In the present method, the closed surfaces on the boundary of the three-dimensional computational domain are represented by hybrid surface grids. The hybrid grids are composed of nonoverlapping structured surface grids joined by an unstructured layer of triangles. Each hybrid grid is constructed from a subset of the physical boundary points on the faces of the component grids.The holes in the component grids are made by using a two-step mark-and-fill method. We first locate all grid cells that intersect the hybrid surface grids. We then apply the ray method to determine whether the grid points in these intersected grid cells are inside or outside the region bounded by the hybrid surface grids. As a result, the boundary of the hole region will be marked and it is a simple matter to then remove all points from the hole by starting from the outside points and traversing along all three grid directions until an inside point is found. To locate the intersecting grid cells, we employ the ray method augmented by an octree-based search technique together with Newton's method to invert the mappings corresponding to each component grid.We demonstrate the hole-cutting method by running the code Chalmesh to generate overlapping grids for a sphere in a box, around the stern of a ship, and around a three-bladed ship propeller.
94%-Effective Policies for a Two-Stage Serial Inventory System with Stochastic Demand
Authors: Niklas Kohl, Jacques Desrosiers, Oli B. G. Madsen, Marius M. Solomon, Francois Soumis, Fangruo Chen
Venue: Management Science (1999)

A two-stage inventory system is considered where Poisson demand occurs at Stage 1, and Stage 1 replenishes its inventory from Stage 2, which in turn orders from an outside supplier with unlimited stock. Each shipment, either to Stage 2 or to Stage 1, incurs a fixed setup cost. Under the assumption that the supply leadtime at Stage 2 is zero, we characterize a simple heuristic policy whose long-run average cost is guaranteed to be within 6% of optimality, i.e., a 94%-effective policy. The paper also provides heuristic policies for more general inventory systems and reports computational results.
A Methodology for Network Topology Design with Link and Node Failures Tolerance
Authors: Adel J. Al-Rumaih, Rana Ejaz Ahmed, Saad Haj Bakry, Abdullah Haj Al-Dhelaan
Venue: International Journal of Network Management (1996)

This article describes a new methodology for network topology design considering the problems of single link-failure and single node-failure tolerances.
Basic compiler algorithms for parallel programs
Authors: Jaejin Lee, David A. Padua, Samuel P. Midkiff
Venue: ACM SIGPLAN Notices (1999)

Traditional compiler techniques developed for sequential programs do not guarantee the correctness (sequential consistency) of compiler transformations when applied to parallel programs. This is because traditional compilers for sequential programs do not account for the updates to a shared variable by different threads. We present a concurrent static single assignment (CSSA) form for parallel programs containing cobegin/coend and parallel do constructs and post/wait synchronization primitives. Based on the CSSA form, we present copy propagation and dead code elimination techniques. Also, a global value numbering technique that detects equivalent variables in parallel programs is presented. By using global value numbering and the CSSA form, we extend classical common subexpression elimination, redundant load/store elimination, and loop invariant detection to parallel programs without violating sequential consistency. These optimization techniques are the most commonly used techniques for sequential programs. By extending these techniques to parallel programs, we can guarantee the correctness of the optimized program and maintain single processor performance in a multiprocessor environment.