ppxscal/embedding_network huggingface dataset:
Positive Dependence Properties of Conditionally Independent Random Lifetimes
Authors: Moshe Shaked, Fabio Spizzichino
Venue: Mathematics of Operations Research (1998)

Conditions under which conditionally independent random variables are positive dependent are described in this paper. For example, it is shown that if the conditionally independent random variables increase in the hazard rate sense in the condition, th en they are WBF (weakened by failures). It is also shown that if the conditionally independent random variables increase in the likelihood ratio sense in the condition, then they are MTP2 (multivariate totally positive of order 2). The results are given for the cases in which the condition is either a random variable or a random vector. Some applications in the areas of imperfect repair, budget allocation, random environments, and discrete-time filtering, illustrate the theory.
Resource partitioning in general purpose operating systems: experimental results in Windows NT
Authors: D. G. Waddington, D. Hutchison
Venue: ACM SIGOPS Operating Systems Review (1999)

The principal role of the operating system is that of resource management. Its task is to present a set of appropriate services to the applications and users it supports. Traditionally, general-purpose operating systems, including Windows NT, federate resource sharing in a fair manner, with the predominant goal of efficient resource utilisation. As a result the chosen scheduling algorithms are not suited to applications that have stringent Quality-of-Service (QoS) and resource management requirements, such as continuous media streaming applications. Several approaches to resource management that are able to meet these requirements, including the use of deterministic schedulers, are well established. Operating systems already exist that provide services for fine-grained resource partitioning and QoS based allocations. Nevertheless, the question arises: can we introduce suitable management mechanisms into general-purpose operating systems that will provide adequate support for the majority of resource sensitive applications, particularly multimedia? Or are there inherent problems in general-purpose operating system architectures that demand significant re-engineering?We attempt to answer this question by proposing the Protected Virtual Machine (PVM) architecture. This introduces mechanisms into Windows NT that enable partitioning of resources and protection from resource interference. The functionality of the PVM architecture is two-fold. First it introduces the necessary scheduling mechanisms and atomic resource abstractions into the operating system, and second it provides a higher level reservation and admission service directly to applications. The resulting system is able to provide both a best-effort service for applications with less stringent needs and a guaranteed service for multimedia and other resource critical processing in a shared environment, By enhancing the existing operating system, legacy applications can still be supported, thus avoiding a prominent obstacle in existing real-time and multimedia operating systems.
The Computer Based Patient Record: A Strategic Issue in Process Innovation
Authors: Claude Sicotte, Jean Louis Denis, Pascale Lehoux
Venue: Journal of Medical Systems (1998)

Reengineering of the workplace through Information Technology is an important strategic issue for today's hospitals. The computer-based patient record (CPR) is one technology that has the potential to profoundly modify the work routines of the care unit. This study investigates a CPR project aimed at allowing physicians and nurses to work in a completely electronic environment. The focus of our analysis was the patient nursing care process. The rationale behind the introduction of this technology was based on its alleged capability to both enhance quality of care and control costs. This is done by better managing the flow of information within the organization and by introducing mechanisms such as the timeless and spaceless organization of the work place, de-localization, and automation of work processes. The present case study analyzed the implementation of a large CPR project (&dollar;45 million U.S.) conducted in four hospitals in joint venture with two computer firms. The computerized system had to be withdrawn because of boycotts from both the medical and nursing personnel. User-resistance was not the problem. Despite its failure, this project was a good opportunity to understand better the intricate complexity of introducing technology in professional work where the usefulness of information is short lived and where it is difficult to predetermine the relevancy of information. Profound misconceptions in achieving a tighter fit (synchronization) between care processes and information processes were the main problems.
Transporting voice traffic over packet networks
Authors: Larry Greenstein
Venue: International Journal of Network Management (1998)

POTS networks are being rapidly superceded by newer, packet-based ones, which allows a greater facility for voice traffic. This article explores the practical issues involved in deploying voice networks over ATM, frame relay and IP. &copy; 1998 by John Wiley & Sons, Ltd.
Evaluation and testing of internet firewalls
Authors: Khalid Al-Tawil
Venue: International Journal of Network Management (1999)

In this article we propose a testing methodology for evaluating Internet firewalls and apply it to compare two popular firewalls. Copyright &copy; 1999 John Wiley Sons, Ltd.
NetSP&mdash;Network Security Program
Authors: Jesper A. Nilausen
Venue: International Journal of Network Management (1996)

This article takes us quickly through a relatively new IBM offering, NetSP &lpar;in fact two offerings&rpar;, which gives users easy access to distributed resources located in the network, and at the same time enables a very high level of access security to these resources.
Efficient Interprocedural Array Data-Flow Analysis for Automatic Program Parallelization
Authors: Junjie Gu, Zhiyuan Li
Venue: IEEE Transactions on Software Engineering (2000)

Since sequential languages such as Fortran and C are more machine-independent than current parallel languages, it is highly desirable to develop powerful parallelization-tools which can generate parallel codes, automatically or semiautomatically, targeting different parallel architectures. Array data-flow analysis is known to be crucial to the success of automatic parallelization. Such an analysis should be performed interprocedurally and symbolically and it often needs to handle the predicates represented by IF conditions. Unfortunately, such a powerful program analysis can be extremely time-consuming if not carefully designed. How to enhance the efficiency of this analysis to a practical level remains an issue largely untouched to date. This paper presents techniques for efficient interprocedural array data-flow analysis and documents experimental results of its implementation in a research parallelizing compiler. Our techniques are based on guarded array regions and the resulting tool runs faster, by one or two orders of magnitude, than other similarly powerful tools.
Collaboration or plagiarism: what happens when students work together
Authors: Janet Carter
Venue: ACM SIGCSE Bulletin (1999)

This paper describes the findings of a small-scale case study concerning the collaborative aspects of student working practices. It is a pilot investigation into the strategies that are employed by students when attempting Object Oriented programming exercises outside the formal classroom setting.Some of the collaborative practices are simple cases of copying, but others, despite falling within the definition of plagiarism, are a beneficial, and possibly useful, means of enhancing the learning process.Although this study only focuses upon a small group of students in one UK University, the practices highlighted are unlikely to be confined to this one setting.
Automatic Caption Localization in Compressed Video
Authors: Yu Zhong, Hongjiang Zhang, Anil K. Jain
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

We present a method to automatically localize captions in JPEG compressed images and the I-frames of MPEG compressed videos. Caption text regions are segmented from background images using their distinguishing texture characteristics. Unlike previously published methods which fully decompress the video sequence before extracting the text regions, this method locates candidate caption text regions directly in the DCT compressed domain using the intensity variation information encoded in the DCT domain. Therefore, only a very small amount of decoding is required. The proposed algorithm takes about $0.006$ second to process a $240 \times 350$ image and achieves a recall rate of $99.17$ percent while falsely accepting about $1.87$ percent nontext DCT blocks on a variety of MPEG compressed videos containing more than $2,300$ I-frames.
A Punctuated-Equilibrium Model of Technology Diffusion
Authors: Christoph H. Loch, Bernardo A. Huberman
Venue: Management Science (1999)

We present an evolutionary model of technology diffusion in which an old and a new technology are available, both of which improve their performance incrementally over time. Technology adopters make repeated choices between the established and the new technology based on their perceived performance, which is subject to uncertainty. Both technologies exhibit positive externalities, or performance benefits from others using the same technology. We find that the superior technology will not necessarily be broadly adopted by the population. Externalities cause two stable usage equilibria to exist, one with the old technology being the standard and the other with the new technology the standard. Punctuations, or sudden shifts, in these equilibria determine the patterns of technology diffusion. The time for an equilibrium punctuation depends on the rate of incremental improvement of both technologies, and on the system's resistance to switching between equilibria. If the new technology has a higher rate of incremental improvement, it is adopted faster, and adoption may precede performance parity if the system's resistance to switching is low. Adoption of the new technology may trail performance parity if the system's resistance to switching is high.
A Second-Order Rosenbrock Method Applied to Photochemical Dispersion Problems
Authors: J. G. Verwer, E. J. Spee, J. G. Blom, W. Hundsdorfer
Venue: SIAM Journal on Scientific Computing (1999)

A second-order, L-stable Rosenbrock method from the field of stiff ordinary differential equations is studied for application to atmospheric dispersion problems describing photochemistry, advective, and turbulent diffusive transport. Partial differential equation problems of this type occur in the field of air pollution modeling. The focal point of the paper is to examine the Rosenbrock method for reliable and efficient use as an atmospheric chemical kinetics box-model solver within Strang-type operator splitting. In addition, two W-method versions of the Rosenbrock method are discussed. These versions use an inexact Jacobian matrix and are meant to provide alternatives for Strang-splitting. Another alternative for Strang-splitting is a technique based on so-called source-splitting. This technique is briefly discussed.
A fully reusable class of objects for synchronization and communication in Ada 95
Authors: Patrick de Bondeli
Venue: ACM SIGAda Ada Letters (1999)

This paper presents a very general class which can be reused to specify and implement any type exporting synchronization or communication properties. The new Ada 95 features modelling inheritance, polymorphism and hierarchies of library units are used extensively in describing the architecture of the class and other new features (access to subprograms, protected types, hellip;) are used for the specification and implementation of the components of the class.Section 2 presents the general architecture of our class. Sections 3, 4, 5 respectively give examples of specification, use and implementation of its components. Section 6 concludes on recalling the full role of formal techniques in our approach (they appear in the present paper only to show that the semantics of our class is defined at a more abstract level than its implementation) and discussing a few interesting points about the way Ada 95 is used here.
Scheduling issues in high-performance computing
Authors: L. W. Dowdy, E. Rosti, G. Serazzi, E. Smirni
Venue: ACM SIGMETRICS Performance Evaluation Review (1999)

In this paper we consider the problem of scheduling computational resources across a range of high-performance systems, from tightly coupled parallel systems to loosely coupled ones like networks of workstations and geographically dispersed meta-computing environments. We review the role of architecture issues in the choice of scheduling discipline and we present a selected set of policies that address different aspects of the scheduling problem. This discussion serves as the motivation for addressing the success of academic research in scheduling as well as its common criticisms.
Is a Bird in the Hand Worth More than Two in the Bush? Limitations of Priority Cognizance in Conflict Resolution for Firm Real-Time Database Systems
Authors: Anindya Datta, Sang H. Son, Vijay Kumar
Venue: IEEE Transactions on Computers (2000)

After a ¿boom¿ period from the late 80s to the early 90s, there appears to have been a reduction in the amount of work published on Concurrency Control (CC) in real-time database systems (RTDBS) in general and firm RTDBS in particular. This may be because existing paradigms (e.g., Optimistic CC) have been pushed to their limits and it is difficult to extract additional meaningful performance. One of the last unresolved bastions of real-time CC is the successful incorporation of priority cognizance. Researchers have speculated that priority cognizant optimistic concurrency control (OCC) algorithms, if designed well, could outperform priority insensitive ones in real-time database systems. So far, however, there is a distinct lack of conclusive proof available on this topic and the priority cognizant OCC algorithms that have appeared so far in the literature cannot claim unilateral superiority over their priority insensitive relatives. We thus surmise that successful incorporation of priority cognizance may lead to an increase in the performance of OCC protocols in firm RTDBSs. Based on this premise, we analyze the issue of priority cognizance and identify a critical condition that must hold for priority cognizant conflict resolution to work. The condition is that, on the average, the conflict sets of validating transactions should have a ¿large¿ number of transactions: We call this a bird in hand more than two in the bush phenomenon. Subsequently, we design a smart priority cognizant OCC variant, which we call OCC-APR, and analyze its performance, as well as that of several other concurrency control algorithms across a wide range of resource contention and system loading parameters. Surprisingly, it turns out that it is very difficult for priority cognizance to work as the above mentioned condition does not, usually, hold. We explain why this occurs and conclude that priority cognizance does not appear to be a promising technique to increase real-time CC performance. The contribution of this paper, thus, is to have laid to rest the ¿priority cognizance¿ issue with regard to real-time CCMs.
Pedagogical power tools for teaching Java
Authors: Jeff Raab, Richard Rasala, Viera K. Proulx
Venue: ACM SIGCSE Bulletin (2000)

We describe a Java toolkit that is designed to support the creation of powerful and extensible GUI interfaces during the first year computer science course. The goals of this toolkit are to provide: bull; an infrastructure for creating well designed programs that illustrates the concepts of computer science and its practical applications bull; an environment for learning the basic ideas of interface design and for experimenting with a variety of designs bull; a paradigm for building interfaces in Java that scales from individual data items to large structures, using recursively displayable container classesAdditionally, the toolkit classes themselves can be studied as examples of proper object oriented design, and of building event listeners.
A feedback based rate control algorithm for multicast transmitted video conferencing
Authors: Hugh M. Smith, Matt W. Mutka, Diane T. Rover
Venue: Journal of High Speed Networks (1998)

This paper presents a feedback based rate control algorithm for video conferencing on the Internet. This algorithm adaptively controls the transmission rate of a video stream, which is being multicast to a heterogeneous group of receivers. The fact that the sender is transmitting a single video stream to many receivers introduces a number of issues. These issues include the variable nature of the available network resources and the fact that there is no easy way to determine the availability of these resources. In addition, even if we were able to track closely the changing network conditions, the best transmission rate for the aggregate means a trade off between high and low end receivers. The algorithm presented in this paper, called the Target Bandwidth Rate Control Algorithm, dynamically controls the output rate of the video coder by receiving and processing bandwidth levels from each receiver in the videoconference. The goal of this algorithm is to maximize the aggregate amount of video displayable at the receivers. This algorithm also allows us to limit the worst case loss experienced by the low-end receivers. In addition to considering the available network bandwidth in the feedback information, this algorithm allows for workstation and user requirements to be considered when determining the senders output rate. In order to show the effectiveness of this approach, we first analyze the algorithms performance in a simulation environment. In this set of tests we study the effects of different configurations of receivers in terms of the number of receivers and availability of resources. Additionally, we have implemented this algorithm in the VIC video conferencing system in order to analyze its effectiveness under real network conditions.
Learning to Improve Coordinated Actions in Cooperative Distributed Problem-Solving Environments
Authors: Toshiharu Sugawara, Victor Lesser
Venue: Machine Learning (1998)

Coordination is an essential technique in cooperative, distributed multiagent systems. However, sophisticated coordination strategies are not always cost-effective in all problem-solving situations. This paper presents a learning method to identify what information will improve coordination in specific problem-solving situations. Learning is accomplished by recording and analyzing traces of inferences after problem solving. The analysis identifies situations where inappropriate coordination strategies caused redundant activities, or the lack of timely execution of important activities, thus degrading system performance. To remedy this problem, situation-specific control rules are created which acquire additional nonlocal information about activities in the agent networks and then select another plan or another scheduling strategy. Examples from a real distributed problem-solving application involving diagnosis of a local area network are described.
Directional Routing via Generalized st-Numberings
Authors: Fred S. Annexstein, Kenneth A. Berman
Venue: SIAM Journal on Discrete Mathematics (2000)

We present a mathematical model for network routing based on generating paths in a consistent direction. Our development is based on an algebraic and geometric framework for defining a directional coordinate system for real vector spaces. Our model, which generalizes graph st-numberings, is based on mapping the nodes of a network to points in multidimensional space and ensures that the paths generated in different directions from the same source are node-disjoint. Such directional embeddings encode the global disjoint path structure with very simple local information. We prove that all 3-connected graphs have 3-directional embeddings in the plane so that each node outside a set of extreme nodes has a neighbor in each of the three directional regions defined in the plane. We conjecture that the result generalizes to k-connected graphs. We also show that a directed acyclic graph (dag) that is k-connected to a set of sinks has a k-directional embedding in (k-1)-space with the sink set as the extreme nodes.
An overview and classification of mediated query systems
Authors: Ruxandra Domenig, Klaus R. Dittrich
Venue: ACM SIGMOD Record (1999)

Multimedia technology, global information infrastructures and other developments allow users to access more and more information sources of various types. However, the &ldquo;technical&rdquo; availability alone (by means of networks, WWW, mail systems, databases, etc.) is not sufficient for making meaningful and advanced use of all information available on-line. Therefore, the problem of effectively and efficiently accessing and querying heterogeneous and distributed data sources is an important research direction. This paper aims at classifying existing approaches which can be used to query heterogeneous data sources. We consider one of the approaches &mdash; the mediated query approach &mdash; in more detail and provide a classification framework for it as well.
Using ASIS for data base insulation
Authors: Pace Drury
Venue: ACM SIGAda Ada Letters (1999)

The SIDPERS-3 project uses ASIS (Ada Semantic Interface Specification) to create Ada code that insulates the typical developer from the intimate details of, and any variations in, COTS (Commercial Off The Shelf) generated Ada code for data base interaction.
Poster session. Internet curriculum. two courses: introductory and advanced
Authors: Ernest Ackermann
Venue: ACM SIGCSE Bulletin (1999)

We describe two courses that deal with the Internet. One is an introductory course with no prerequisites and the other is more advanced and focuses on providing Web services.
Two-handed input using a PDA and a mouse
Authors: Brad A. Myers, Kin Pou Lie, Bo-Chieh Yang
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (2000)

We performed several experiments using a Personal Digital Assistant (PDA) as an input device in the non-dominant hand along with a mouse in the dominant hand. A PDA is a small hand-held palm-size computer like a 3Com Palm Pilot or a Windows CE device. These are becoming widely available and are easily connected to a PC. Results of our experiments indicate that people can accurately and quickly select among a small numbers of buttons on the PDA using the left hand without looking, and that, as predicted, performance does decrease as the number of buttons increases. Homing times to move both hands between the keyboard and devices are only about 10% to 15% slower than times to move a single hand to the mouse, suggesting that acquiring two devices does not cause a large penalty. In an application task, we found that scrolling web pages using buttons or a scroller on the PDA matched the speed of using a mouse with a conventional scroll bar, and beat the best two-handed times reported in an earlier experiment. These results will help make two-handed interactions with computers more widely available and more effective.