bluuebunny/crossref_metadata_2025 huggingface dataset:
Memory management techniques for Time Warp on a distributed memory machine
Authors: Preiss Bruno R. , Loucks Wayne M.
Published: January 2007

This paper examines memory management issues associated with Time Warp synchronized parallel simulation on distributed memory machines. The paper begins with a summary of the techniques which have been previously proposed for memory management on various parallel processor memory structures. It then concentrates the discussion on parallel simulation executing on a distributed memory computer—a system comprised of separate computers, interconnected by a communications network. An important characteristic of the software developed for such systems is the fact that the dynamic memory is allocated from a pool of memory that is shared by all of the processes at a given processor.

This paper presents a new memory management protocol, pruneback, which recovers space by discarding previous states. This is different from all previous schemes such as artificial rollback and cancelback which recover memory space by causing one or more logical processes to roll back to an earlier simulation time.

The paper includes an empirical study of a parallel simulation of a closed stochastic queueing network showing the relationship between simulation execution time and amount of memory available. The results indicate that using pruneback is significantly more effective than artificial rollback (adapted for a distributed memory computer) for this problem. In the study, varying the memory limits over a 2:1 range resulted in a 1:2 change in artificial rollback execution time and almost no change in pruneback execution time.
An improved cost function for static partitioning of parallel circuit simulations using a conservative synchronization protocol
Authors: Kapp Kevin L. , Hartrum Thomas C. , Wailes Tom S.
Published: January 2007

Distributing computation among multiple processors is one approach to reducing simulation time for large VLSI circuit designs. However, parallel simulation introduces the problem of how to partition the logic gates and system behaviors of the circuit among the available processors in order to obtain maximum speedup. A complicating factor that is often ignored is the effect of the time-synchronization protocol (conservative [1] or optimistic [2]). Inherent in the partitioning problem is the question of how to effectively measure the relative quality of a partition. This paper describes an objective cost function for measuring the relative quality of a task partition that includes a synchronization factor for a conservative NULL-message protocol. A graph-based partitioning tool based on this cost function is used to perform the static task allocation for parallel simulation of a structural VHDL circuit. Results for two 1000 – 4000 gate circuits demonstrate that the additional consideration of the synchronization protocol in the cost function generates partitions that exhibit improved speedup.
A case study in simulating PCS networks using Time Warp
Authors: Carothers Christopher D. , Fujimoto Richard M. , Lin Yi-Bing
Published: January 2007

There has been rapid growth in the demand for mobile communications over the past few years. This has led to intensive research and development efforts for complex PCS (personal communication service) networks. Capacity planning and performance modeling is necessary to maintain a high quality of service to the mobile subscriber while minimizing cost to the PCS provider. The need for flexible analysis tools and the high computational requirements of large PCS network simulations make it an excellent candidate for parallel simulation.

Here, we describe our experiences in developing two PCS simulation models on a general purpose distributed simulation platform based on the Time Warp mechanism. These models utilize two widely used approaches to simulating PCS networks: (i) the call-initiated and (ii) the portable-initiated models. We discuss design decisions that were made in mapping these models to the Time Warp executive, and characterize the workloads resulting from these models in terms of factors such as communication locality and computation granularity. We then present performance measurements for their execution on a network of workstations. These measurements indicate that the call-initiated model generally outperforms the portable initiated model, but is not able to capture phenomenon such as the “busy line” effect. Moreover, these studies indicate that the high locality in large-scale PCS network simulations make them well-suited for execution on general purpose parallel and distributed simulation platforms.
Buffer management in shared-memory Time Warp systems
Authors: Fujimoto Richard M. , Panesar Kiran S.
Published: January 2007

Mechanisms for managing message buffers in Time Warp parallel simulations executing on cache-coherent shared-memory multiprocessors are studied. Two simple buffer management strategies called the sender pool and receiver pool mechanisms are examined with respect to their efficiency, and in particular, their interaction with multiprocessor cache-coherence protocols. Measurements of implementations on a Kendall Square Research KSR-2 machine using both synthetic workloads and benchmark applications demonstrate that sender pools offer significant performance advantages over receiver pools. However, it is also observed that both schemes, especially the sender pool mechanism, are prone to severe performance degradations due to poor locality of reference in large simulations using substantial amounts of message buffer memory. A third strategy called the partitioned buffer pool approach is proposed that exploits the advantages of sender pools, but exhibits much better locality. Measurements of this approach indicate that the partitioned pool mechanism yields substantially better performance than both the sender and receiver pool schemes for large-scale, small-granularity parallel simulation applications.

The central conclusions from this study are: (1) buffer management strategies play an important role in determining the overall efficiency of multiprocessor-based parallel simulators, and (2) the partitioned buffer pool organization offers significantly better performance than the sender and receiver pool schemes. These studies demonstrate that poor performance may result if proper attention is not paid to realizing an efficient buffer management mechanism.
Parallel gate-level circuit simulation on shared memory architectures
Authors: Bagrodia Rajive , Chen Yu-an , Jha Vikas , Sonpar Nicki
Published: January 2007

This paper presents the results of an experimental study to evaluate the effectiveness of parallel simulation in reducing the execution time of gate-level models of VLSI circuits. Specific contributions of this paper include (i) the design of a gate-level parallel simulator that can be executed, without any changes on both distributed memory and shared memory parallel architectures, (ii) demonstrated speedups with both conservative and optimistic simulation protocols (almost all previous studies on circuit simulation have failed to extract speedups with conservative protocols); in particular we showed that a speedup of about 3 was obtained on 8 processors of Sparc1000 for conservative algorithms and about 2 for optimistic algorithms for circuits in the ISCAS85 benchmark suite; and (iii) performance comparison between shared memory and distributed memory implementations of the simulator.
Effectiveness of global event queues in rollback reduction and load balancing
Authors: Prasad Sushil K. , Naqib Basem
Published: January 2007

Compared to highly optimized optimistic simulators which use local event queues for individual processors on a shared-memory computer, we demonstrate that employing a single global event queue drastically reduces the number of rollbacks, brings down the storage requirements, and achieves superior load balance. On a bus-based Silicon Graphics multiprocessor, these virtues consistently translated into faster execution times and higher speedups on those synthetic networks of medium- to coarse-grained logical processes which were ridden with rollbacks and load imbalance on local-queue-based simulators. A dynamic randomization-based load distribution scheme for local-event-queue simulators is also shown to be an effective improvement.
Distributed simulation with locality
Authors: Blanchard T. D. , Lake T. W.
Published: January 2007

We describe MOSS, a small language of mobile distributed objects and system-wide references, uncommitted to any distributed simulation protocol, but which can be executed as a distributed conservative simulation with automatic deduction of lookahead. We show how the MOSS programmer can control the dynamic distribution and locality of simulation objects by simple means which provide natural modelling functions. Preliminary results show how programmed locality can reduce communication costs in simulation.
Real time character scaling and rotation
Authors: Andrews David L. , Brown Randy , Caldwell Charles , Wheeler Andrew
Published: January 2007

This paper describes a real time signal processing subsystem used to perform character scaling and rotation. First, the algorithms used in the subsystem are described. The algorithms were developed for performing sorting decisions on mail for the USPS. The computational complexity of the algorithms implemented in the subsystem is then reviewed, and finally the implementation of the algorithms in discrete logic, DSP's, and FPGA's is discussed.
A low-cost, high-yield intelligent decision support system for Navy contract termination processing
Authors: Warkentin Merrill E. , Carlson Christopher K. , Ruth Stephen R.
Published: January 2007

This paper describes a contract termination processing model developed for the US Naval Supply Systems Command (NAVSUP). CONTERM serves as an intelligent decision support system for processing contracts recommended as termination candidates. The system employs a benefit-cost model formula, derived from domain experts, to evaluate prospective supply contract termination actions. It emulates expert decision behavior typical of competent contract administrators in this domain. System features are provided for documentation of the evaluation, processing, collection of data for subsequent analysis, and merging and reporting collective statistics from operation. Because of its low unit costs of development and its potential for rapid fanout into operational use in scores of Navy contracting sites, it may be a paradigm for other high yield --- low cost models.
Investigating DEs with CRACK and related programs
Authors: Wolf Thomas , Brand Andreas
Published: January 2007

The aim of the package to be described is to try modularizing the investigation of differential equations for which there are no complete algorithms available yet. All, that is available for such problems are algorithms for special situations, e.g. when first integrals with a simple structure exist (e.g. polynomial in first derivatives) or when the problem has infinitesimal symmetries. In all such cases, finally a system of differential equations has to be solved which is overdetermined in the sense that more conditions have to be satisfied than there are unknown functions. To do a variety of such investigations efficiently, like a symmetry analysis, application of symmetries, determination of first integrals, differential factors, equivalent Lagrangians, the strategy is to have one package (CRACK) for simplifying DEs and solving simple DEs as effective as possible and to use this program as the main tool for all the above mentioned investigations. For each investigation there is then only a short program necessary to just formulate the necessary conditions in form of an overdetermined DE-system and to call CRACK to solve this, possibly in a number of successive calls. The examples below shall indicate the range of possible applications.
Can information systems concepts be assimilated into non-IS courses?
Authors: Schell George P.
Published: January 2007

The American Assembly of Collegiate Schools of Business (AACSB) is encouraging schools to teach core topics across a spectrum of courses. Subjects would not be artificially forced into a certain course because of departmental boundaries but would be introduced according to their relevance to the topic being presented. Information systems (IS) topics have received attention possibly because the wording of the current AACSB curriculum standards no longer implies that a separate course is required for information systems.Many discussions about curriculum changes affecting IS have been made without quantitative information. Evidence has not been gathered about the qualifications of non-IS faculty to teach IS topics or even faculty preferences for delivery of IS topics. The questionnaire used to gather data for this article revealed that non-IS faculty strongly prefer a separate, required IS course over integrating IS topics into non-IS courses. The introductory IS course provides the bulk of knowledge that most business students receive about information systems. If students are not well taught by qualified faculty then their ability to use and assimilate IS and IS technology is diminished. This article brings some quantitative evidence to the debate and argues that IS topics beyond computer literacy are best taught by IS faculty.
Growing pains—and successes—in transforming the information systems organization for client/server development
Authors: Nance William D.
Published: January 2007

Information systems (IS) groups are under increasing pressure to contribute to organizational performance and to support, or even drive, broad organizational transformation efforts through the successful exploitation of information technology (IT). Using a "sociocentric" model of organizational work, this paper analyzes the experiences of one company's IS group that recently embarked on a long-term, enterprise-wide client/server system development initiative designed to transform organizational decision support processes. Even though the client/server initiative is still in its infancy and has not yet delivered high-impact applications, it has brought about substantial changes in the nature of work in the IS group. These changes range from new philosophies, methodologies, and technologies to shifts in the skills, communication patterns, control structures and management styles required to develop and manage information systems.
An auxiliary processor to integrate MATLAB with APL
Authors: Gidh Kedar
Published: January 2007

To augment the functionality of APL, an auxiliary processor was implemented to access MATLAB. This provides APL users the capability to use MATLAB's presentation-quality graphics and application-specific toolboxes from within APL. Data arrays can be exchanged between APL and MATLAB using the auxiliary processor. The auxiliary processor was written in C to be used under Unix.
The practical management of computer ethics problems
Authors: Smith John W.
Published: January 2007

Ethics problems are as varied and diverse as the people and cultures of our institutions. There are certain characteristics of the problems, however, that are relatively common. Interestingly, the more intense the conflict, the more they seem to share these common properties. If you are aware of these characteristics you can recognize what you are getting into and take remedial action before the situation gets out of control.
Managing color on the desktop, from scanned image to the printed page
Authors: Galanter Philip
Published: January 2007

Current desktop computing systems support color graphics as a matter of course, and many support 24-bit color at an affordable price. But as artists and other media producers have found, having a 24-bit color card and monitor is only the first step towards a useful digital imaging system. On a typical desktop computer, simply scanning an image and then printing it out will usually result in colors that are faded, muddy, or just plain wrong.
Gopherspace
Authors: DeSimone Albert
Published: January 2007

Assembling and utilizing the creative and technical energy to conceive of and develop the Internet Gopher must have been an exciting and challenging task for the University of Minnesota's Internet Gopher Development Team. But with the popularity of Gopher throughout the world, the team members can certainly be proud of their efforts.
Delegation versus concatenation or cloning is inheritance too
Authors: Taivalsaari Antero
Published: January 2007

In this paper a simple prototype-based model of object-oriented programming is introduced. Unlike previous prototype-based systems, which use
delegation
to achieve incremental modification of objects, the suggested model is based on
concatenation:
linear composition of object interfaces. The model eliminates the notions of delegation and parent slots from prototype-based programming, and shows that the essence of object-oriented programming can be captured using only a small number of user-level language constructs.
A leaf-cell generator for silicon compilers
Authors: de Abreu Moreira D. , Walczowski L. T.
Published: January 2007

A program for the design of leaf cells for silicon compilers of digital VLSI (Very Large Scale Integrated) circuits, is being developed. This program uses rule based reasoning and genetic algorithmic search techniques, whenever each is appropriate. Leaf cells are subcircuits of a complexity comparable with SSI (Small Scale Integration) components such as one-bit adders, flip-flops or multiplexers. They typically contain between 10 to 100 transistors. Silicon compilers can use libraries of ready designed leaf cells or each leaf cell can be automatically generated [1] by synthesis tools such as the program we are developing. The main advantage of the synthesis approach is that circuit performance will not be sacrificed since a new, optimal layout will be produced whatever the complexity of the circuit and whenever the fabrication process is upgraded.
Computer simulation
Authors: Nance Richard E. , Overstreet C. Michael
Published: January 2007

"Computer simulation" is a broadly used term that can take on different meanings depending often on the disciplinary context. Within statistics the term is applied to repetitive sampling, described in more specific terms as "Monte Carlo simulation." Those working with computational solutions of numerical systems, typically modeling fluid flow or ballistics, use the term in place of the more specific "continuous simulation." While those modeling queueing or inventory problems in computer science, operations research or management science, use the term in place of the more accurate descriptor "discrete event simulation." This third substitution has become more prevalent; because the problem domains addressed have emerged as the most prominent. That is not to say that no meaningful work is on-going in the other disciplinary areas; rather the other two identified more readily with disciplinary areas, have profited from their ready recognition as belonging to statistics or applied mathematics.
Key-based partitioned bit-sliced signature file
Authors: Zezula Pavel , Ciaccia Paolo , Tiberio Paolo
Published: January 2007

A new signature file organization is proposed as a combination of two orthogonal partitioning strategies, the key-based and the bit-sliced, respectively. The design results from theoretical analysis of these elementary approaches in which performance is analytically studied respecting a simplified abstract storage structure model. The new organization is able to achieve very high search performance for queries containing arbitrary number of query terms - bit-sliced (key-based) organization is good only for queries containing few (many) terms, quite bad performance is obtained in the other cases. Update performance is also discussed and a generalization of the method, able to adjust the trade-off between the search efficiency and the maintenance costs, is put forward for consideration. The proposal is also compared with similar approaches in the field of signature files.
Manufacturing resource planning on a PC local area network
Authors: Kee H. Clark , Post Roy L.
Published: January 2007

This paper details a large APL programming project of 12 man years. An integrated software system structured on the principles of MRP (manufacturing resource planning) was implemented by a Bristol-Myers in house team for use in a new manufacturing facility.

The system applies off-the-shelf technology in innovative ways, using STSC APL*PLUS/PC as the only programming language, to build a very sophisticated application on IBM/PCs fully sharing data in a secure environment via the NESTAR Plan 4000 local area network and file server.

The paper describes technical, application, and business aspects of the project. It should be of interest to (1) persons contemplating or involved in developing APL applications on a local area network, (2) persons developing or who want to develop an integrated manufacturing system, and (3) anyone interested in large APL applications.

The plant at which this system operates is located in Nijimegen, the Netherlands, and produces powdered infant formula and other nutritional beverages.

The authors believe that this paper is of value both in its description of technological hurdles and achievements, and in the details of the business application.
The scope of APL in nuclear measurements
Authors: Bastian C.
Published: January 2007

The whole range of data acquisition and analysis in experimental nuclear physics can be covered with a few APL application workspaces. Typical steps of the treatment of statistical data are highlighted and compared with nearly-equivalent solutions in other languages.
APL in quality business management
Authors: McKee Terence J.
Published: January 2007

Companies monitor their processes so that they can identify actions that need to be taken. Measures such as monthly sales, expenses by category, inventory levels, days debt and computer service availability are recorded and reported.

This paper introduces the application of quality control techniques to help you determine whether a process needs intervention. You will want to identify when a short term fluctuation becomes significant, when a longer term trend appears and most important, determine what sort of action is appropriate.

There are many potential pitfalls in presentation techniques even when the correct information is being used. Some are mentioned, but are not the prime purpose of this paper. There are good examples in reference 1.
Compiling optimized array operations at run-time
Authors: Christopher Thomas W. , Wallace Ralph W.
Published: January 2007

Experiments were performed for APL functions on a Vax-750 running UNIX to compare the execution times of two types of interpreted code run time run time compiled code for the dyadic function subtract. The data type and size varied over integer, real, one element, and a 5x5x5x5x5 (=3125) element arrays. The experiment showed a range of more than 2.5:1 in execution times of interpretive code to compiled code.
DELIS: A decision support system generator for frequency data
Authors: Butterworth Richard W. , Stephan Robert A.
Published: January 2007

The title of this paper suggests two concepts, namely Decision Support Systems (DSS) and frequency style data, that were built upon by the APL application called “DELIS”. DELIS was developed originally for interactive display of certain frequency data arrays, and has evolved over the past 8 years into a comprehensive system for developing a broad class of related applications. Our paper's objective is to explain the title concepts well enough to give the reader a feel for the DELIS design and to explain generally how APL was used in its implementation. The concepts work well together in a way that seems natural to APL users and that may have applicability for other designers and developers of APL based information systems.
Field results with the APL compiler
Authors: Wiedmann Clark
Published: January 2007

The STSC compiler is now in use at customer sites. We can finally answer the question of whether the compiler is effective at reducing CPU time for real applications, and whether it is cost effective to invest the extra effort to speed up applications with the compiler. We have found from numerous case studies that (1) it takes an APL programmer about 3 days to learn about the compiler and begin to use it effectively; (2) customers have speeded up whole applications by factors of 1.2 to 9; (3) usually about one-tenth of an application needs to be compiled to speed it up; (4) the extra effort to analyze an application and compile parts of it can be as low as 1% of the time required to develop it; (5) we have documented cases where the purchase price of the compiler is cost-justified in two months of use.
Writing multi-user applications in APL2
Authors: Brown James A.
Published: January 2007

This paper presents a general scheme for quickly implementing multi-user applications. Several facilities of
APL2
are discussed which make
APL2
a particularly suitable solution for such problems. The resulting implementation is used to demonstrate how the advanced facilities of
APL2
affect the writing of programs. The simplicity of the programs indicates how productive
APL2
can be. The paper does not discuss the necessary user-friendly front end that any application should have because that is no different from a single user application.
A perfect square root routine
Authors: McDonnell E. E.
Published: January 2007

To characterize a much larger effort, the design and implementation of a square root routine for IPSA APL is described. The routine is perfect in the sense that, if the result can be represented exactly, the exact result is given. If the result cannot be represented exactly, it is rounded to the nearest representable floating point number. The use of APL in designing and testing this routine is emphasized.
Collaborative realtime process management
Authors: Wærn Yvonne , Jones Patricia
Published: January 2007

Several situations in modern working life imply that people have to cooperate in order to handle dynamic systems. The work is distributed in several respects; people work with different tasks and have different expertise, they are often geographically distributed and they work at different times or cover different time scales. The activities are often time critical and cooperation has to be efficient. The problems involved in these situations have great economical and societal impacts. Approaches to the problems require expertise in several domains.The objectives of the workshop was to identify key features of collaborative process management and to identify critical needs in the domain of collaborative process management.
Equal access to information for all
Authors: Karshmer Arthur I. , Kaugars Karlis
Published: January 2007

On March 27th, 1995, the World Wide Web and the information super highway took a big step on the road to becoming the new window into the world of information. On that date MCI began its InternetMCI service. The net surfer can now shop, get critical information and news, get investment advice and much more. And this is only the first step. By a series of simple mouse clicks, the user has almost instant access to services and products almost anywhere in the world.The use of modern computers and software by the visually handicapped has become more difficult over the past few years. In earlier systems the user interface was a simple character based environment. In those systems, simple devices like screen readers, braille output and speech synthesizers were effective. Current systems now run Graphical User Interfaces (GUIs) which have rendered these simple aids almost useless. In no area has this problem become more important than in technologies for the handicapped. What has become enabling technology for the sighted has become disabling technology for the visually impaired.
Social integration of people with disabilities
Authors: Earls John A. M.
Published: January 2007

This research examines the use of a computer bulletin board as a means of facilitating the social integration of people with disabilities.The literature review identifies significant parallel research strands in the- Social Integration of People with Disabilities- Social Psychology of Information Technology.To develop a model which draws these important strands together three groups interact using a computer bulletin board. The groups are people with disabilities, tertiary computing students and speech and occupational therapists. The study conducts pre, post and long term attitude tests, collects data via the operating system, records all textual data generated over a three month period (almost 6000 pages) and ultimately carries out longitudinal case studies with the disabled participants.The short term (three months) attitude changes are inconclusive, but the longer term (two year) changes show a highly significant improvement in the attitude of people with disabilities who participated. The case studies showed that all participants with disabilities had improved their self image, their confidence and had made identifiable integrative gains. These included becoming politically active, living independently, gaining employment for over fifty percent of those involved, publishing literary works and taking up further study. In addition the clearly demonstrated benefits evoked very positive changes in their peer group, in structural changes within the organisation, in Federal Government Department of Community Services and Health service delivery and in the provision of an "Access Australia" innovative award to the Redcliffe City Municipal Library.Grounded Theory was used to identify a range of factors which supported or inhibited the Integrative process.The study demonstrated the value of integrating the two research streams, the benefits of the process (with minimal disadvantages) and the efficacy of the model. A significant issue emerging was the need for people with disabilities to be empowered, able to make their own choices and develop their own models. As a consequence the study concluded by outlining relevant areas of suggested future development in the mainstream and producing a skeletal model as a basis for future integrative work involving the participants themselves.
Book review: The Implementation of Prolog By Patrice Boizumault Translated from the original French by Ara M. Djamboulian and Jamal Fattouh (Princeton University Press, 1993)
Authors: Tinkham Nancy Lynn
Published: January 2007

As a programming language, Prolog was designed to reflect conceptual problem-solving methods rather than the architecture of any particular computer; it encourages the programmer to solve problems by describing facts and relationships, instead of trying to fit the problem into a set of memory locations and machine operations on a computer. Prolog is thus, by design, a step farther from the machine than most conventional imperative programming languages.
Book review: Robot Learning by Jonathan H. Connell and Sridhar Mahadevan (Kluwer Academic Publishers, 1993)
Authors: Demiris John
Published: January 2007

In this very good book, the editors Jonathan Connell and Sridhar Mahadevan have brought together several good researchers with good ideas creating a very interesting collection of eight papers on Robot Learning. This book is one of the first in this area and will serve well as a supplementary for courses in AI and Robotics.
The Graz digital library effort
Authors: Maurer H.
Published: January 2007

Tile Graz Digital Library effort is based on an extension of WWW, the "first second generation hypermedia system" Hyper-G. The reason for choosing Hyper-G is that it not only supports all kinds of searches, but allows to define arbitrary scopes for searches, tlnat it supports multitinguality and that, due to its link concept, allows to (a) conduct discussions around any part of any document and (b) allows to customize the data base for personal purposes. For more information on Hyper-G see http://hyperg.iicm.tu-graz.ac.at.
Hypertext links in Lotus Notes and the World Wide Web
Authors: Ehrlich Kate , Lee Alex , Ritari Phillip
Published: January 2007

At the Digital Libraries conference in Texas in 1994 we presented a paper describing an ethnographic study of information access in a customer support organization [1]. That study revealed the highly collaborative nature of information filtering and retrieval. In particular, support analysts relied on each other to fill in anecdotal and experiential information missing from written documentation and reason through that information to solve customer problems. Colleagues also routinely shared references to relevant sources of information. This behavior is very similar to what we have observed informally in which people will spontaneously share references to interesting documents with friends and colleagues. In fact, we found that workgroups often include at least one person who is especially skilled at browsing through large amounts of often diverse information and then making his or her findings available to others generally with some commentary on its relevance and/or intrinsic value. Based on these data and observations we developed a system in Lotus Notes to let people share references to on-line documents. The system automatically encoded contextual information such as the name of the document, its date and its source along with the hypertext link, and provided space for the person to add comments of any length [3]. The resulting "pointer" could be sent to colleagues in email or saved in a Notes database as a personal bookmark. These pointers were more useful than just sending doc links because the recipient would get some context that would help him/her decide whether to follow the link to the document. We also enhanced the basic doc link technology in Notes to automatically open or add and open the referenced database if the user did not have that database on their workspace. This enhancement meant that location and availability of the database was transparent to the user.
Building personal digital libraries from network sources
Authors: Goh Dion , Kacmar Chuck
Published: January 2007

Our work is focused on personal digital libraries and personal information spaces. In this context, a personal digital library (PDL) is a collection of multimedia objects (text, graphics and audio), created by an individual and/or drawn from resources elsewhere on the Internet. The benefits of this approach include a reduction in user disorientation and an increased likelihood that the user will find relevant material since the structure of the information space is defined and customized entirely by the user. This is achieved through metadata and cataloging facilities which allow for the creation and maintenance of the personal digital library.
Visual querying for digital libraries using dynamic hypertext aggregates
Authors: BenMrad Montassar , Coray Giovanni
Published: January 2007

In the last few years, digital libraries have received a lot of attention given a maturation of recent technological achievements, particularly in the case of wide-spread computer networks, high-capacity storage media and more powerful personal computers [I]. Nevertheless, user needs must often be expressed through cryptic command languages that are still difficult to learn and to master. Documents relevant to the query are usually presented as a fiat list of titles that can be called by the user.
The role of compression in document databases
Authors: Moffat Alistair , Zobel Justin , Witten Ian H. , Bell Timothy C.
Published: January 2007

The extensive use of compression means that the MG retrieval system is capable of managing multi-gigabyte document collections in an effective and efficient manner. This article reviews the main features of MG and notes its relevance to large hypermedia collections.
A digital library and network for electronic teaching and learning materials for the Australian University system
Authors: Greenhalgh Michael
Published: January 2007

ArtServe (http://rubens.anu.edu. all) went live on 4th January 1994, and currently gets about 2,800 accesses per day from all over the world. The material on offer consists of: (a) the Diocletian tutorial mentioned above; (b) 2,800 images of "Prints & Print History", together with their associated data files, available both with inline thumbnail images and via a fill-in-the-form database-query interface. The images date from the beginning of printmaking to about 1900, so as to avoid copyright problems; (c) 2,600 images of "Architecture of the Mediterranean Basin", currently available only via a fill-in-the-forms database-query interface; (d) a TextSearcher, commissioned by the author, which operates with plain ASCII text files and also with HTML files (see 6.2.2); (e) a 120,000-word book, written by the author, on "The Greek and Roman Cities of Western Turkey", "sliced up" into HTML format; (f) a further collection of images of Mediterranean art & architecture. Most images are accessible via a forms query interface, with the option of returning hotspotted records (i.e. for those with slow network connections) or records with inline GIFs as well.
A hypermedia approach to digital libraries
Authors: Balasubramanian V.
Published: January 2007

Digital libraries can provide users with fast access to large, complex, richly connected, and cross-referenced bodies of information. They can be considered as applications based on the hypermedia paradigm. Hypermedia is hypertext with multimedia. The principle behind hypertext or hypermedia is nodes of information (concepts) associated through links (relationships). It is essentially non-linear organization and presentation of information. Nodes can contain text, graphics, animation, audio, video, and even other applications.
TNT: a talking tutor 'n' trainer for teaching use of interactive computer systems
Authors: Nakatani L. H. , Egan D. E. , Ruedisueli L. W. , Hawley P. M. , Lewart D. K.
Published: January 2007

Tutor 'N' Trainer (TNT) is an automated tutor for vi, the UNIX™ system screen editor. TNT fosters learning by doing. The
Tutor
component guides the student's practice with spoken instruction and feedback. The
Trainer
component assures safety during practice by permitting only previously taught and appropriate operations. Individualization and effectiveness are achieved in two ways: special
helper keys
enable slow learners to get extra help and repeat troublesome tasks; and
practice loops
force slow learners to practice tasks repeatedly until competency is achieved.
A cognitive model of database querying: a tool for novice instruction
Authors: Schlager M. S. , Ogden W. C.
Published: January 2007

Two experiments examine the effects of incorporating user knowledge into the design of training materials for a database querying system. In Experiment 1 an informal cognitive model of a query language is derived from the verbal reports of expert users, and incorporated into existing documentation. Two groups of subjects were then asked to solve queries using either the revised or original manual. In Experiment 2 the cognitive model was formalized to explicitly describe the conceptual and procedural information that was incorporated into training materials. Three groups of subjects then received either a conceptual model, procedural model, or neither in addition to basic instructions, and then solved four sets of queries. The results show that whether or not a given type of information facilitates performance depends on the type of query, and whether the model is consistent with the operation of the query system.
The effects of structured, multi-level documentation
Authors: Holt R. W. , Boehm-Davis D. A. , Schultz A. C.
Published: January 2007

The effects of general global documentation, detailed step-by-step documentation, and combined global and detailed documentation were examined for high, medium, and low experienced students. The 198 students in this study used a word-processing program to complete two problems during a two-hour session. Results from univariate and multivariate analyses indicated that both general time measures for reading documentation and completing problems as well as the student users' reactions to the documentation, the program, and the computer system were affected by either the type of documentation, the level of experience, or both of these factors.
A formal interface design methodology based on user knowledge
Authors: McDonald J. E. , Dearholt D. W. , Paap K. R. , Schvaneveldt R. W.
Published: January 2007

In this paper we propose a formal interface design methodology based on user knowledge. The general methodology consists of 1) obtaining distance estimates for pairs of system units (objects, actions, concepts), 2) transforming the distance estimates using scaling techniques (e.g., Pathfinder network analysis), and 3) organizing the system interface based on the scaling solution. Thus, the organization of the system is based on the cognitive models of users rather than the intuitions of designers. As an example, we discuss the application of our methodology to the design of a network-based indexing aid for the UNIX on-line documentation system (MAN).
A model of mental model construction
Authors: Lewis C.
Published: January 2007

Learning to control a computer system from limited experience with it seems to require constructing a mental model adequate to indicate the causal connections between user actions, system responses, and user goals. While many kinds of knowledge could be used in building such a model, a small number of simple, low-level heuristics is adequate to interpret some common computer interaction patterns. Designing interactions so that they fall within the scope of these heuristics may lead to easier mastery by learners.
Intelligent interfaces: user models and planners
Authors: Quinn L. , Russell D. M.
Published: January 2007

To meet the challenge of constructing interfaces for increasingly complex multifunctional products, designers will be attracted by the promise offered by “intelligent” systems. However, the value of such sophisticated systems must be measured in terms of the quality of their user's models. One such intelligent interface — an Expert Help System — has been designed, implemented, and evaluated. We argue that the operability problems noted in users' interactions with this system are attributable to lack of a strong user model in the system interface. Such a model plays a critical role in determining the effectiveness of the system's ability to monitor the user's planning activities. We discuss the requirements of a strong user model and provide an example of how such a model might be integrated into a planner-based intelligent interface.
A traffic for MPEG-coded VBR streams
Authors: Krunz Marwan , Hughes Herman
Published: January 2007

Compression of digital video is the only viable means to transport real-time full-motion video over BISDN/ATM networks. Traffic streams generated by video compressors exhibit complicated patterns which vary from one compression scheme to another. In this paper we investigate the traffic characteristics of video streams which are compressed based on the MPEG standard. Our study is based on 23 minutes of video obtained from an entertainment movie. A particular significance of our data is that it contains all types of coded frames, namely: Intra-coded (I), Prediction (P), and Bidirectional (B) MPEG frames. We describe the statistical behavior of the VBR stream using histograms and autocorrelation functions. A procedure is developed to determine the instants of a scene change based on the changes in the size of successive
I
frames. It is found that the length of a scene can be modeled by a geometric distribution.A model for an MPEG traffic source is developed in which frames are generated according to the compression pattern of the captured video stream. For each frame type, the number of cells per frame is fitted by a lognormal distribution whose parameters are determined by the frame type. The appropriateness and limitations of the model are examined by studying the multiplexing performance of MPEG streams. Simulations of an ATM multiplexer are conducted, in which traffic sources are derived from the measured VBR trace as well as the proposed model. The queueing performance in both cases is found to be relatively close.
A case for two-level distributed recovery schemes
Authors: Vaidya Nitin H.
Published: January 2007

Most distributed and multiprocessor recovery schemes proposed in the literature are designed to tolerate arbitrary number of failures. In this paper, we demonstrate that, it is often advantageous to use "two-level" recovery schemes. A
two-level
recovery scheme tolerates the
more probable
failures with low performance overhead, while the less probable failures may be tolerated with a higher overhead. By minimizing the overhead for the more frequently occurring failure scenarios, our approach is expected to achieve lower performance overhead (on average) as compared to existing recovery schemes.To demonstrate the advantages of two-level recovery, we evaluate the performance of a recovery scheme that takes two different types of checkpoints, namely, 1-checkpoints and
N
-checkpoints. A single failure can be tolerated by rolling the system back to a 1-checkpoint, while multiple failure recovery is possible by rolling back to an
N
-checkpoint. For such a system, we demonstrate that to minimize the average overhead, it is often necessary to take
both
1-checkpoints and
N
-checkpoints.While the conclusions of this paper are intuitive, the work on design of appropriate recovery schemes is lacking. The objective of this paper is to motivate research into recovery schemes that can provide multiple levels of fault tolerance.
Fundamental results on the performance of ATM multiplexers with applications to video teleconferencing
Authors: Elwalid Anwar , Heyman Daniel , Lakshman T. V. , Mitra Debasis , Weiss Alan
Published: January 2007

The main contributions of this paper are two-fold. First, we prove fundamental, similarly behaving lower and upper bounds, and give an approximation based on the bounds, which is effective for analyzing ATM multiplexers, even when the traffic has many, possibly heterogeneous, sources and their models are of high dimension. Second, we apply our analytic approximation to statistical models of video teleconference traffic, obtain the multiplexing system's capacity as determined by the number of admissible sources for given cell loss probability, buffer size and trunk bandwidth, and, finally, compare with results from simulations, which are driven by actual data from coders. The results are surprisingly close. Our bounds are based on Large Deviations theory. Our approximation has two easily calculated parameters, one is from Chernoff's theorem and the other is the system's dominant eigenvalue. A broad range of systems are analyzed and the time for analysis in each case is a fraction of a second.