bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of M/G/1/SRPT under transient overload
Authors: Bansal Nikhil , Harchol-Balter Mor
Published: January 2007

This short paper contains an approximate analysis for the M/G/1/SRPT queue under alternating periods of overload and low load. The result in this paper along with several other results on systems under transient overload are contained in our recent technical report [2].
Scheduling periodic task graphs with communication delays
Authors: Riabov Anton , Sethuraman Jay
Published: January 2007

We consider the problem of finding an optimal assignment of tasks, which constitute a parallel application, to an unlimited number of identical processors. The precedence constraints among the tasks are given in the form of a directed acyclic graph (DAG). We are given processing times for each task and the communication delays between precedence-constrained tasks, which are incurred if the corresponding tasks are executed on different processors. Furthermore, the system must be able to process real-time periodic input with a fixed period. This problem occurs, for example, in multiprocessor scheduling of video processing applications, where each frame has to be processed by a number of software filters, and some filters use data pre-processed by other filters, thus forming a DAG of data dependencies. We formulate several variants of this problem, and briefly discuss some of our results for special precedence graphs.
Stochastic online binpacking problem
Authors: Gamarnik David
Published: January 2007

We consider the following stochastic bin packing process: the items of different sizes arrive at times
t
= 0, 1, 2, … and are packed into unit size bins using "largest first" rule. The unpacked items form queues. Coffman and Stolyar [3] introduced this system and posed the following question: under which conditions expected queue lengths are bounded (system is stable)? We provide exact computable conditions for stability of this system using Lyapunov function technique. The result holds for a very general class of distributions of the arrival processes.
Mobile ad hoc networking and the IETF
Authors: Macker Joseph P. , Corson M. Scott
Published: January 2007

This article is part of a continuing series to discuss ongoing activities within the mobile ad hoc networking (manet) working group (WG) of the IETE This article provides a brief overview of recent events.
Constructing minimum energy mobile wireless networks
Authors: Li Xiang-Yang , Wan Peng-Jun
Published: January 2007

Energy conservation is a critical issue in designing wireless ad hoc networks, as the nodes are powered by batteries only. Given a set of wireless network nodes, the directed weighted transmission graph G
t
has an edge
uv
if and only if node
v
is in the transmission range of node
u
and the weight of
uv
is typically defined as ||
uv
||
α
+
c
for a constant
2
≤ α ≤
5
and c >
0
. The minimum power topology G
m
is the smallest subgraph of G
t
that contains the shortest paths between all pairs of nodes, i.e., the union of all shortest paths. In this paper, we described a distributed position-based networking protocol to construct an enclosure graph G
e
, which is an approximation of G
m
. The time complexity of each node
u
is O
(min(
d

G
t

(u)
d

G
e

(u),
d

G
t

(u)
log
d

G
t

(u))),
where d
G
(u)
is the degree of node
u
in a graph G. The space required at each node to compute the minimum power topology is O
(
d

G
t

(u)).
This improves the previous result that computes G
m
in O
(
d

G
t

(u)
3
)

time using O
(
d

G
t

(u)
2
)

spaces. We also show that the average degree d

G
e

(u)
is usually a constant, which is at most
6.
Our result is first developed for stationary network and then extended to mobile networks.
The golden rule of complementary feedback
Authors: Dambacher Jeffrey M. , Rossignol Philippe A.
Published: January 2007

This work demonstrates the occurrence of the Fibonacci sequence in the qualitative analysis of Lotka---Volterra dynamical systems. Herein we show the golden ratio to govern reciprocal effects between neighboring variables in simple food web models. Impacts to the entire community resulting from perturbation of a population variable can be predicted from the adjoint of the community (Jacobian) matrix, which we render in qualitative terms of complementary feedback cycles. Sequences of complementary feedback cycles follow the Fibonacci sequence, and are also configured as multiples and overlapping harmonics thereof. We derive an absolute-feedback matrix that clarifies the sequence. Patterns of complementary feedback cycles are determined by community structure, which can be portrayed and understood in terms of signed digraph structure.
Mobile ad hoc networking and the IETF
Authors: Macker Joseph P. , Corson M. Scott
Published: January 2007

This article is part of a continuing series to discuss ongoing activities within the mobile ad hoc networking (manet) working group (WG) of the IETF. This article provides a brief overview of recent events.
PC based precision timing without GPS
Authors: Pásztor Attila , Veitch Darryl
Published: January 2007

A highly accurate monitoring solution for active network measurement is provided without the need for GPS, based on an alternative software clock for PC's running Unix. With respect to clock
rate,
it's performance exceeds common GPS and NTP synchronized software clock accuracy. It is based on the TSC register counting CPU cycles and offers a resolution of around 1ns, a rate stability of 0.1PPM equal to that of the underlying hardware, and a processing overhead well under 1µs per timestamp. It is scalable and can be run in parallel with the usual clock. It is argued that accurate rate, and not synchronised offset, is the key requirement of a clock for network measurement. The clock requires an accurate estimation of the CPU cycle period. Two calibration methods which do not require a reference clock at the calibration point are given. To the TSC clock we add timestamping optimisations to create two high accuracy monitors, one based on Linux and the other on Real-Time Linux. The TSC-RT-Linux monitor has offset fluctuations of the order of 1µs. The clock is ideally suited for high precision active measurement.
Exact aggregate solutions for M/G/1-type Markov processes
Authors: Riska Alma , Smirni Evgenia
Published: January 2007

We introduce a new methodology for the exact analysis of M/G/1-type Markov processes. The methodology uses basic, well-known results for Markov chains by exploiting the structure of the repetitive portion of the chain and recasting the overall problem into the computation of the solution of a finite linear system. The methodology allows for the calculation of the aggregate probability of a finite set of classes of states from the state space, appropriately defined. Further, it allows for the computation of a set of measures of interest such as the system queue length or any of its higher moments. The proposed methodology is exact. Detailed experiments illustrate that the methodology is also numerically stable, and in many cases can yield significantly less expensive solutions when compared with other methods, as shown by detailed time and space complexity analysis.
Inferring client response time at the web server
Authors: Olshefski David P. , Nieh Jason , Agrawal Dakshi
Published: January 2007

As businesses continue to grow their World Wide Web presence, it is becoming increasingly vital for them to have quantitative measures of the client perceived response times of their web services. We present Certes (CliEnt Response Time Estimated by the Server), an online server-based mechanism for web servers to measure client perceived response time, as if measured at the client. Certes is based on a model of TCP that quantifies the effect that connection drops have on perceived client response time, by using three simple server-side measurements: connection drop rate, connection accept rate and connection completion rate. The mechanism does not require modifications to http servers or web pages, does not rely on probing or third party sampling, and does not require client-side modifications or scripting. Certes can be used to measure response times for any web content, not just HTML. We have implemented Certes and compared its response time measurements with those obtained with detailed client instrumentation. Our results demonstrate that Certes provides accurate server-based measurements of client response times in HTTP 1.0/1.1 [14] environments, even with rapidly changing workloads. Certes runs online in constant time with very low overhead. It can be used at web sites and server farms to verify compliance with service level objectives.
Search and replication in unstructured peer-to-peer networks
Authors: Lv Qin , Cao Pei , Cohen Edith , Li Kai , Shenker Scott
Published: January 2007

Decentralized and unstructured peer-to-peer networks such as Gnutella are attractive for certain applications because they require no centralized directories and no precise control over network topology or data placement. However, the flooding-based query algorithm used in Gnutella does not scale; each individual query generates a large amount of traffic and large systems quickly become overwhelmed by the query-induced load. This paper explores various alternatives to Gnutella's query algorithm and data replication strategy. We propose a query algorithm based on multiple random walks that resolves queries almost as quickly as Gnutella's flooding method while reducing the network traffic by two orders of magnitude in many cases. We also present a distributed replication strategy that yields close-to-optimal performance.
Web server benchmarking using parallel WAN emulation
Authors: Simmonds Rob , Williamson Carey , Bradford Russell , Arlitt Martin , Unger Brian
Published: January 2007

This paper discusses the use of a parallel discrete-event network emulator called the Internet Protocol Traffic and Network Emulator (IP-TNE) for Web server benchmarking. The experiments in this paper demonstrate the feasibility of high-performance WAN emulation using parallel discrete-event simulation techniques on shared-memory multiprocessors. Our experiments with the Apache Web server achieve 3400 HTTP transactions per second for simple Web workloads, and 1000 HTTP transactions per second for realistic Web workloads, for static document retrieval across emulated WAN topologies of up to 4096 concurrent Web/TCP clients. The results show that WAN characteristics, including round-trip delays, link speeds, packet losses, packet sizes, and bandwidth asymmetry, all have significant impacts on Web server performance. WAN emulation enables stress testing and benchmarking of Web server performance in ways that may not be possible in simple LAN test scenarios.
Polynomial solution of recurrence relation and differential equation
Authors: Ronveaux A. , Thiry G.
Published: January 2007

We propose a REDUCE implementation of the SHORE compatibility criterion between recurrence relation and second order linear homogenous differential equation both satisfied by orthogonal polynomials. We discuss some different strategies developed around the symbolic matrix triangularization in the light of meaningful classical and semi-classical cases.
With J for TeX
Authors: Reiter Cliff
Published: January 2007

Last summer I asked the Jforum for advice regarding the conversion of J text to a format suitable for placing J expressions and session logs into TeX word processing documents. There were a couple dozen follow-up posts to the Jforum and I received many private e-mail messages. There have been independent threads regarding TeX in comp.lang.apl too. I was quite surprised by the high level of interest and impressed by the number of sophisticated comments. I also enjoyed a few good laughs. This note offers some remarks on the Jforum discussion, what I eventually did, what the alternatives were, and what I might have done if I could have foreseen the future. While the core computation was simple escape sequence substitution, there also were subtle contexts for modifications when lines end and when box drawing characters appear. J's adverb facility helped with those situations and the use of J-defined function keys made the J to TeX conversion much easier.
A proposal for a namespace facility in APL+WIN
Authors: Siegel David E.
Published: January 2007

"Namespaces" have been implemented in some APL dialects, to reduce name scope and avoid name conflicts. Other implementations, including APL+WIN, do not yet support such a feature. This is an unofficial proposal for the design and implementation of such a feature. The design is, in the author's opinion, an improvement on those already implemented. It is presented in the hope of stimulating discussion, which might lead to further improvements in the proposal, and the decision, by language implementers, to adopt such an improved proposal.
Book Review: Artificial Intelligence Applications in Materials Science by Ralph J. Harrison and Lewis D. Roth (The Metallurgical Society, 1987)
Authors: Hedeen Alien
Published: January 2007

This volume assesses the state of the art in machine vision, emphasizing industrial applications. Topics covered include machine vision applications in manufacturing, smart sensors for machine vision, computation with parallel image processors, learning structural descriptions of shape, extracting of three-dimensional structure and motion from images, analysis of range images, and new approaches to computer architecture for machine vision applications.
A pictorial aid for programming expert systems
Authors: Schwartz Edward N.
Published: January 2007

The knowledge engineering and software development tasks involved in constructing software for an expert system are very different from the task of designing an imperative program. Some of the problems in the construction of a rule-based expert system include deducing the heuristics of the expert, converting these heuristics into a working taxonomy and rule base, and ordering the rule base so that the system performs efficiently and correctly. A pictorial method of knowledge representation that we call a "k-tree" greatly facilitates these tasks.
Book review: INTERFACING THOUGHT: COGNITIVE ASPECTS OF COMPUTER-HUMAN INTERACTION ed. by John M. Carroll (MIT Press)
Authors: Gray Wayne D. , Atwood Michael E.
Published: January 2007

With
Interfacing Thought
, editor John Carroll brings together some of the best cognitive scientists working in the field of human-computer interaction. (HCI). Individually, many of the papers in this book are very good and represent recent applied cognitive research in human-computer interaction. Collectively, the papers emphasize the research and theoretical side of the HCI equation and reflect the diversity of approaches for applying cognitive science to human-computer interaction.
The Cutplane: a tool for interactive solid modeling
Authors: Edwards Laurence , Kessler William , Leifer Larry
Published: January 2007

Today, most solid modeling systems are used only in the final stages of design, where iterations are driven by analysis rather than creative exploration of alternative solutions. These systems have complex interfaces, slow response, and do not provide a convenient way of specifying a three dimensional position using a two dimensional display screen. As such they are not viable alternatives to visualization methods traditionally used in early design.This paper presents a geometric modeling system which incorporates a new concept for intuitively and unambiguously specifying and manipulating points or features in three dimensional space. The central concept, the Cutplane, consists of a plane that moves through space under control of a mouse or similar input device. The intersection of the plane and any object is highlighted, and only this highlighted section can be selected for manipulation. Selection is accomplished with a crosshair that is constrained to remain within the plane, so that the relationship between the crosshair and the feature of interest is immediately evident. Although the idea of a section view is not new, previously it has been used as a way to reveal hidden structure, not as a means of manipulating objects or indicating spatial position, as is proposed here.
Preferences for power in expert systems by novice users
Authors: Coovert Michael D. , McNelis Kathleen , Ramakrishna Kamesh , Sala Eduardo
Published: January 2007

The focus in building expert systems has typically been to build them to be as powerful as possible. These systems continue to impact directly or indirectly on nearly every aspect of our lives. Among the myriad applications which currently exist, expert systems have been designed to diagnose medical problems (Buchnan & Shortliffe, 1984), instruct students (Freedman, 1987), and schedule airline reservations (Rich, 1981.
Evaluation of mental models and meta models through interactions between users and helpers about software usage problems
Authors: Dehdashti Parto
Published: January 2007

This research investigates the concept of mental models by concentrating on the conversations between student users who as a result of encountering a problem on a software ask for assistance from student helpers who are assigned to support computer use. The research question is whether a human helper provides appropriate help for the user (problem solved in user's mind) if the helper understands the problem and the software from the user's view in addition to his/her own. A user's understanding of a software, user's mental model, and a helper's understanding of a user's understanding of that software, helper's meta model, are compared through software characteristics: objects, syntax, semantics, and actions.
Dialing a name: alphabetic entry through a telephone keypad
Authors: Fast Lisa , Ballantine Roy
Published: January 2007

Problem:---The standard home telephone has an extremely limited user interface device (few keys, no 'Q' or 'Z' etc.)--- People are reluctant to read manuals, remember codes or use prompt cards--- Given these, is it possible to provide sopisticated character-based features such as personal directories on basic residential sets, and with the right interface, would people be able to use them without documentation support?
An authoring system for the creation of interfaces for disabled users
Authors: Ferrier Linda , Fell Harriet
Published: January 2007

This authoring system is intended to aid teachers, health practitioners and parents of severely disabled children in the creation of software accessible to these children. Using our system, care providers will be able to interactively create their own teaching, testing, communication and play programs to suit the needs of children who are dependent on alternative interfaces.
Problem solving performance and display preference for information displays depicting numerical functions
Authors: LaLomia Mary J. , Coovert Michael D. , Salas Eduardo
Published: January 2007

As the amount of information accessible via computer systems increases, so do problems associated with presenting information that can be assimilated easily and accurately. Many researchers advocate the graphical presentation of information to allow for effortless perception and organization of information. Research in many diverse areas has focused on determining effective information presentation. Educational researchers compared graphical and tabular displays in classroom settings (Rigney & Lutz, 1976; Washburne, 1927) and results indicate pictorial or graphical representations effectively aid problem solving performance. Statisticians contributing to this area have concentrated on design aspects of graphs and tables, and have produced manuals describing design guidelines. Research generated by statisticians (Carter, 1947;1948a;1948b) indicates that graphs enhanced performance for tasks requiring data interpolation, while tables enhanced performance for tasks requiring the reading of specific values. The major focus from the Human Factors perspective concerns general design issues, such as brightness, contrast, and color. Tullis (1981) compared tabular and graphical displays for a telephone diagnostic task and found no differences for type of display. Schutz (1961) compared line, vertical bar, and horizontal bar graphs for a trend analysis task and found subjects performed best with the line graph, followed by the vertical bar and lastly with the horizontal bar graph.
Triangular solution of linear systems in tensor product format
Authors: Fernandes Paulo , Plateau Brigitte
Published: January 2007

This paper presents an algorithm to solve linear systems expressed by a matrix stored in a tensor product format. The proposed solution is based on a LU decomposition of the matrix keeping the tensor product structure. It is shown that the complexity of the decomposition is negligible and the backward and forward substitutions are no more complex than two standard vector-matrices multiplications. Finally, applications of the proposed algorithm and the comparison with other similar techniques are discussed.
On the use of partial symmetries for lumping Markov chains
Authors: Capra L. , Dutheillet C. , Franceschinis G. , Ilié J. M.
Published: January 2007

In this paper a method is proposed, to exploit partially symmetric behavior of systems for efficient performance evaluation. The method works on performance models described with the Stochastic Well-Formed Nets (SWN) formalism: it allows to automatically discover partial symmetries in the model behavior, and directly derive a lumped Markov chain from it, suitable for performance analysis purposes. With respect to previous works on automatic exploitation of symmetries in SWNs, the proposed approach allows a significantly higher reduction of the state space size in many practical cases.
Computer algebra
Authors: Buchberger Bruno
Published: January 2007

Mathematical software systems, such as Mathematica, Maple, Derive, and so on, are substantially based on enormous advances in the area of mathematics known as
Computer Algebra
or
Symbolic Mathematics.
In fact, everything taught in high school and in the first semesters of a university mathematical education, is available in these systems 'at the touch of the button'. Will mathematics become unnecessary because of this? In the three sections of this essay, I answer this question for non-mathematicians, for mathematicians and for (future) students of mathematics.
The user interface in text retrieval systems
Authors: Drori Offer
Published: January 2007

Ever since the advent of on-line computer systems, the development of the user interface has been a key issue in research and applications. The main function of the user interface is to mediate between the system operator and the computer programs that run the information systems.The nature of the interface required by information systems and the functions with which it must provide the user has been studied. It can be said that there are certain rules to be adhered to in the design of any information system, and that there are certain rules characteristic of specific information systems only. (MicrosoftG, 1995)(Galitz, 1994) (MicrosoftU, 1995) (Shneiderman, 1998).The aim of this article is to define the user interface characteristic of text retrieval systems, which generally differ in nature from other information systems.
Better structured control in J
Authors: van Batenburg F. H. D.
Published: January 2007

A new primitive is proposed to replace the various keywords that are now necessary for structured programming. Furthermore, an associated primitive is suggested to take care of all types of jumping. At the end of this paper, several programs are presented in their original programming style together with the alternative where the conventional control keywords are replaced by the new primitive.
A collaborative demonstration of reverse engineering tools
Authors: Storey Margaret-Anne D. , Sim Susan Elliott , Wong Kenny
Published: January 2007

This paper describes a
collaborative structured demonstration
of reverse engineering tools that was presented at a working session at WCRE 2001 in Stuttgart, Germany. A
structured demonstration
is a hybrid tool evaluation technique that combines elements from experiments, case studies, technology demonstrations, and benchmarking. The essence of the technique is to facilitate learning about software engineering tools using a common set of tasks. The collaborative experience discussed at WCRE involved several peer and complementary technologies that were applied in concert to solve a real life reverse engineering problem. For the most part, the tool developers themselves applied their own tools to this problem. Preliminary results have shown to the research community that we still have much to learn about our tools and how they can be applied as part of a reverse engineering and reengineering process. Consequently, the participants agreed to continue participation in this demonstration beyond the WCRE event.
Knowledge worker constraints in the productive use of information technology
Authors: Drury D. H. , Farhoomand A.
Published: January 2007

The impact of Information Technology on managing enterprises continues unabated. Realizing the potential of IT has become a critical concern as the investments mount exponentially. The prosperity of organizations requires that IT resources are used productively by people.This study tests for constraints in the productive use of Information Technology by knowledge workers in organizations. The QRS® NUD*IST™ analysis package is used to analyze one hundred and twenty-five knowledge workers' written assessments. The non-directive assessments identified infrastructure, technical, information, and task categories of issues. The sub-categories of these issues lead to the identification of the structure of constraints.Information Technology can be better utilized to address users needs. The analyses reveal that infrastructure issues are critical. Organizations are not providing support necessary to utilize IT effectively. Technical issues are also important. The expected advantages of IT, such as speed and reliability, do not match knowledge workers expectations. Instead, they are perceived as constraints. The gap between expected and realized IT capabilities is much larger than expected. This leads to difficulties in alienation, anxiety, overload, and lower productivity. Knowledge workers offered their own solutions to resolving the principal, and sub-categories of constraints. Their views provide the basis for addressing practical problems and future research directions in improving knowledge worker productivity using Information Technology.
Classification trees for problems with monotonicity constraints
Authors: Potharst R. , Feelders A. J.
Published: January 2007

For classification problems with ordinal attributes very often the class attribute should increase with each or some of the explaining attributes. These are called classification problems with monotonicity constraints. Classical decision tree algorithms such as CART or C4.5 generally do not produce monotone trees, even if the dataset is completely monotone. This paper surveys the methods that have so far been proposed for generating decision trees that satisfy monotonicity constraints. A distinction is made between methods that work only for monotone datasets and methods that work for monotone and non-monotone datasets alike.
Learning missing values from summary constraints
Authors: Wu Xintao , Barbará Daniel
Published: January 2007

Real-world data sets often contain errors and inconsistency. Even though this is a very important problem it has received relatively little attention in the research community. In this paper we examine the problem of learning missing values when some summary information is available. We use linear algebra and constraint programming techniques to learn the missing values using apriori-known summary information and that derived from the raw data. We reconstruct the missing values by different methods in three scenarios: ideal-constrained, under-constrained, and over-constrained. Furthermore, for a range query involving missing values, we also give the lower bound and upper bound for the values using constraint programming techniques. We believe that theory of linear algebra and constraint programming constitutes a sound basis for learning missing values when summary information is available.
Exploiting succinct constraints using FP-trees
Authors: Leung Carson Kai-Sang , Lakshmanan Laks V. S. , Ng Raymond T.
Published: January 2007

Since its introduction, frequent-set mining has been generalized to many forms, which include constrained data mining. The use of
constraints
permits user focus and guidance, enables user exploration and control, and leads to effective pruning of the search space and efficient mining of frequent itemsets. In this paper, we focus on the use of
succinct constraints.
In particular, we propose a novel algorithm called
FPS
to mine frequent itemsets satisfying succinct constraints. The FPS algorithm avoids the generate-and-test paradigm by exploiting succinctness properties of the constraints in a FP-tree based framework. In terms of functionality, our algorithm is capable of handling not just the succinct aggregate constraint, but any succinct constraint in general. Moreover, it handles multiple succinct constraints. In terms of performance, our algorithm is more efficient and effective than existing FP-tree based constrained frequent-set mining algorithms.
Is pushing constraints deeply into the mining algorithms really what we want?
Authors: Hipp Jochen , Güntzer Ulrich
Published: January 2007

The common approach to exploit mining constraints is to push them deeply into the mining algorithms. In our paper we argue that this approach is based on an understanding of KDD that is no longer up-to-date. In fact, today KDD is seen as a human centered, highly interactive and iterative process. Blindly enforcing constraints already during the mining runs neglects the process character of KDD and therefore is no longer state of the art. Constraints can make a single algorithm run faster but in fact we are still far from response times that would allow true interactivity in KDD. In addition we pay the price of repeated mining runs and moreover risk reducing data mining to some kind of hypothesis testing. Taking all the above into consideration we propose to do exactly the contrary of constrained mining: We accept an initial (nearly) unconstrained and costly mining run. But instead of a sequence of subsequent and still expensive constrained mining runs we answer all further mining queries from this initial result set. Whereas this is straight forward for constraints that can be implemented as filters on the result set, things get more complicated when we restrict the underlying mining data. Actually in practice such constraints are very important, e.g. the generation of rules for certain days of the week, for families, singles, male or female customers etc. We show how to postpone such row-restriction constraints on the transactions from rule generation to rule retrieval from the initial result set.
Designing earcons with musical grammars
Authors: Hankinson John C. K. , Edwards Alistair D. N.
Published: January 2007

Many blind and partially-sighted computer users have come to rely on auditory computer interfaces to interact with their computer. By recognising sounds made by the computer, blind users can extract information from the auditory display which is presented visually to sighted users. Sighted users can also benefit from using an auditory interface in conjunction with their existing visual display.Earcons have evolved as a means of representing concepts in such auditory displays as short sound motives. These motives usually consist of a small number of notes, with a distinct rhythm and dynamic contour. They are constructed according to rules devised by Blattner [1] and developed by Brewster et al. [2, 3]. Although they appear to be musical fragments, many fundamental musical concepts are not taken into account during their design.In fact, many early earcon designers tended restrict the maximum number of notes within an earcon to four, as any longer sequence would have a melodic connotation. The presence of a tune was thought to be distracting and hence the use of musical tensions, etc. was avoided. Instead of shying away from the powerful capabilities music affords, it is postulated here that musical structures should be used to our advantage, to remove the tight restrictions placed upon the design of earcons.It is proposed that the use of a musical grammar during the design of a set of earcons can impose a number of valuable constraints upon the choice of earcon motif. These constraints are advantageous as they allow a basic structure to be built into the surface form of each earcon. This in turn allows only certain combinations of earcons to combine with each other. A grammatical property is therefore imposed upon the interface which provides extra feedback to the user when inappropriate combinations occur.
Problems in making telecommunications services accessible
Authors: Maguire Martin
Published: January 2007

Information technology is continually developing and in the last few years there has been a rapid growth in electronic telecommunications to provide Internet and other network-based services. Interest in using telecommunications to provide services to the public is growing, with a number of pilot services being set up across the country to explore market potential and/or stimulate demand.Administrations across Europe are now using telecommunications technology to provide citizens with information (Hoare, 1998). The British Government, for instance, has issued a directive that 25% of all civil service communications must be on-line by 2002. This is intended to provide savings in paperwork and a streamlined service.An area of possible government assistance is to provide the public with on-line information about welfare benefit entitlement. This may have benefits for all members of society but could be of particular value for retired and older members of the public, many of whom do not always claim their entitlement. It is estimated in the UK, for example, that one million pensioners could be entitled to Income Support that they are not claiming (Benefits Agency, 1998). To provide information to the public, the Benefits Agency produces a website of over 1,000 pages for customers to browse through which can be viewed at http://www.dss.gov.uk/ba. Yet while many people are now connected to the Internet, and the EU average is 25 computers connected per thousand people, (Lennon, 1999) the number of older or retired people using it is still quite small. An indication of this is given by the results of the worldwide 10th Georgia Tech web survey (GVU, 1999). The survey, conducted in 1998, received 5,022 responses of which only 2.7% were from people who were 66 years of age and over.This raises the key question of whether older people will be able to benefit from the promise of the connected future, with information available electronically on tap, or whether they will get left behind. This also represents a lost opportunity for suppliers as, according to Oftel (the UK telephone watchdog organisation) and disability campaign groups, A growing grey market containing millions of potential customers is being ignored in the telecoms boom, Dawe (1998). This paper, therefore, discusses a number of issues relating to making telecommunication services accessible to the population as a whole.
Raising awareness among designers accessibility issues
Authors: Velasco Carlos A. , Verelst Tony
Published: January 2007

We are in the middle of a revolution similar to that of the industrial revolution of the 19

th

century, the Information Society. This revolution is affecting the way we work, the way we study, the way we shop, and many other aspects of our daily life. Concepts such as teleworking, e---commerce, co-operative work, tele---cottage or tele---training are becoming part of our regular vocabulary.The birth of this new society has many implications for everybody. It will open new opportunities, but it will close many others. Information is the keyword. Society might be split into two sectors: those who are wired and those who will stay un---wired. Although while you are an active participant in the events, it is difficult to analyze the facts happening in your world with some perspective, we feel that people with disabilities cannot afford to stay out of the loop.The concern of many people on these issues was the seed of ISdAC International Association. It was obvious that we had to inform our constituency about these changes. Conventional channels were no longer effective, and new approaches had to be found. In the middle of the fight, we must be aware of many accessibility issues. We realized that we had a twofold target: not only we had to reach our constituency, but we had to deal with content providers and software developers as well. We knew that we shall play the role of a bridge between the designers and a market sector which influence will not be negligible.This presentation will not focus in a particular technical issue, but will present some snapshots of our experience in relation with the topics of this workshop: Web design and software development.
Establishing quality control in software agents
Authors: Benedicenti Luigi , Wang Victor Wei , Lee Peter , Paranjape Raman
Published: January 2007

This paper illustrates the results of a research effort to measure the quality of software agents written in Java using extreme programming. A factoring of quality has been chosen in accordance with the properties and limitations of the type of products and development method considered. The use of the representational theory of measurement gave quantitative measures. The measure itself is then used to identify quality clusters that define an ordinal quality taxonomy. The result is a measure of quality that depends only on code, that is easy to implement and to take, and that also gives an indication of the improvements to low-quality classes.
Quick-tests for characterizing distributed systems
Authors: Cormier Rick , Guy Ed , Ruddock David E
Published: January 2007

This paper discusses some problems caused by inadequately characterizing distributed and system architectures. It presents a classification system for decomposing distributed systems and presents a few simple test cases. To allow system designers to characterize different aspects of their environments, we have started a collection of simple Quick-Tests.
A note on the use of Java in scientific computing
Authors: Villacis Juan
Published: January 2007

Java provides an easy-to-use language and platform for writing distributed, network-aware applications. For the scientific computing community, Java has the potential of extending the range and usefulness of scientific codes, as well as widening the codes current user base. However, certain features of Java may limit its usefulness as a platform in which to develop and deploy scientific codes. In this paper, we analyze where Java could be used within scientific computing, and examine several Java-based systems that aim to provide tools and runtimes suitable for programming scientific codes within distributed computing environments.
An optimal service ordering for a world wide web server
Authors: Dalal Amy Csizmar , Jordan Scott
Published: January 2007

We consider alternative service policies in a web server with impatient users. User-perceived performance is modeled as an exponentially decaying function of the user's waiting time, reflecting the probability that the user aborts the download before the page is completely received. The web server is modeled as a single server queue, with Poisson arrivals and exponentially distributed file lengths. The server objective is to maximize average revenue per unit time, where each user is assumed to pay a reward proportional to the perceived performance. When file lengths are i.i.d., we prove that the optimal service policy is greedy, namely that the server should choose the job with the highest potential reward. However, when file lengths are independently drawn from a set of exponential distributions, we show the optimal policy need not be greedy; in fact, processor sharing policies sometimes outperform the best greedy policy in this case.
Boosting I/O performance of internet servers with user-level custom file systems
Authors: Wang Jun , Min Rui , Wu Zhuying , Hu Yiming
Published: January 2007

Previous studies have shown that disk I/O times are one of the major performance bottlenecks of Internet servers such as proxy cache servers. Most conventional file systems do not work well for such systems because of their very high overheads. Although Special-purpose operating systems may achieve high performance, it is very difficult and expensive to design and maintain. They also have very poor portability. In this paper we propose to built user-space, customized file systems for Internet servers so as to achieve high-performance, low-implementation-cost and good portability at the same time. To provide an example of such systems, we presented a novel scheme called
WPSFS
that can drastically improve I/O performance of proxy servers and other applications. WPSFS is an application-level software component of a proxy server which manages data on a raw disk or disk partition. Since the entire system runs in the user space, it is easy and inexpensive to implement. It also has good portability and maintainability. With efficient in-memory meta-data data structures and a novel file system called
Page-structured file system(PFS)
, WPSFS achieves 9-20 times better I/O performance than the state-of-the-art SQUID server running on a Unix Fast File System, and 4-10 times better than the improved SQUIDML.
Equivalent differentiated services for AODVng
Authors: Montenegro Gabriel , Gaidioz Benjamin , Primet Pascale , Tourancheau Bernard
Published: January 2007

A well-known research challenge is the establishment of some quality of service in an ad hoc network. Such a fluid and dynamic environment does not lend itself to extensive state-building approachess like Intserv. Diffserv, in which packets are treated according to some class aggregation seems to be a better match. Diffserv provides strong guarantees to applications by being mainly based on admission control, policing and provisioning. In this paper, we present the "Equivalent Differentiated Services" (EDS) per-hop behavior. EDS provides a set of best-effort services with differentiated performances. We show how EDS could benefit ad hoc networks.
Using computer algebra methods to determine the chemical dimension of finitely ramified Sierpinski carpets
Authors: Franz Astrid , Schulzky Christian , Hoffmann Karl Heinz
Published: January 2007

We present a new algorithm for calculating the chemical dimension
d
1
of finitely ramified Sierpinski carpets. Using an algorithm of Dijkstra, we compute iteratively, using
Mathematica
, the shortest paths through a carpet. The scaling exponent of the lengths of these shortest paths over the linear size of the carpet is
d
min
the minimum path dimension, which is related to the chemical dimension.
A fast dynamic channel assignment algorithm for packet services in DECT
Authors: Capone Antonio , Musumeci Luigi
Published: January 2007

In this paper we consider the use of DECT access for packet data services. DECT systems are characterized by a dynamic channel selection algorithm which allows to reuse the available radio resources in a flexible way. The standard channel allocation procedure results inefficient for packet data applications characterized by short and frequent messages, which determine fast varying traffic conditions. We propose an enhanced dynamic channel selection algorithm, which allows to fulfil the requirements of packet access in a more efficient way. The performance characteristics of the new and standard algorithm have been evaluated by simulation, and refer both to a scenario for only packet data services and an integrated scenario for voice and data services.
GSM network signaling
Authors: Lin Yi-Bing
Published: January 2007

GSM is a wireless digital signaling network standard designed by standardization committees from the major European telecommunications operators and manufacturers. This article introduces the software platform for GSM network signaling protocol called Mobile Application Part (MAP). We describe the MAP services, the MAP protocol machine, the MAP dialog model, and then illustrate the MAP specific service primitives by an example.
Subscriber-assisted handoff support in multimedia PCS
Authors: Jiang Shengming , Tsang Danny H. K. , Li Bo
Published: January 2007

Handoff support is one of the key elements in cellular Personal Communication Systems (PCS). Traditional approaches hide handoff support from the subscriber. However, the main difficulty in handoff support stems from terminal mobility which can only be controlled by the subscriber, who may again have different requirements of mobility support under different environments. Therefore, we suggest that the subscriber should participate in handoff support in the following manner: first, the subscriber is encouraged to declare the requirement of mobility support at call setup time; second, when a handoff cannot be supported, the subscriber should be informed in advance so that (s)he can decide whether or not to control movement since a subscriber may sacrifice mobility for maintaining communication in progress. This approach can reduce call dropping rate and improve resource utilization. We will describe this approach and propose a service classification for mobility support in this paper.
Interworking of a distributed architecture for wireless PCS networks with conventional networks
Authors: Kalbag R. S. , Medhi D.
Published: January 2007

A distributed architecture for wireless PCS networks is appealing due to the separation of call and connection control and the use of operations which run in parallel that can result in reduced data management load, signaling load as well as reduced post-dial delay; the Distributed Architecture for Wireless PCS Networks (DAWN) we have recently developed is such an architecture. On the other hand, centralized architecture such as IS-41 has already been deployed in several wireless networks. Thus, due to imbedded base of conventional architecture such as the IS-41 architecture, the successful deployment of a distributed architecture such as DAWN is highly dependent on the ability to phase in the new architecture and, consequently, to provide seamless interworking capabilities so that a mobile user can move between any two areas where the architectures are different. In this paper, we address the interworking aspects of DAWN with IS-41 based networks. Various IS-41 call scenarios are presented to demonstrate the workings of the interworking function. Interworking with PSTN (public switched telephone network) and handling of intersystem handoffs is also discussed.
A one-way packet communication channel with retransmissions
Authors: Davidson Boris , Bostian Charles
Published: January 2007

The goal of any strategy used to share a communication link is to provide a maximally reliable channel for the greatest possible number of users. It is of particular interest to have an efficient method of resource sharing for one-way communication channels. This paper concerns an application in which a large population of users transmits on a common radio channel to a single central receiver. The channel provides for no return path indicating successful reception. Each user makes an initial transmission, and then the message is repeated some number of times. A technique with retransmissions that increases the probability of successful one-way message transmission is proposed, its theory is formulated, and the results are analyzed and discussed. This technique presents a method for achieving certain throughput on a one-way packet transmission channel with anticipated traffic loading by trading off between various channel parameters. In addition, a computer simulation is performed verifying the developed channel model, and its confidence intervals are determined.