bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance prediction for random write reductions
Authors: Jin Ruoming , Agrawal Gagan
Published: January 2007

In this paper, we revisit the problem of performance prediction on shared memory parallel machines, motivated by the need for selecting parallelization strategy for
random write reductions.
Such reductions frequently arise in data mining algorithms.In our previous work, we have developed a number of techniques for parallelizing this class of reductions. Our previous work has shown that each of the three techniques,
full replication, optimized full locking,
and
cache-sensitive,
can outperform others depending upon problem, dataset, and machine parameters. Therefore, an important question is,
"Can we predict the performance of these techniques for a given problem, dataset, and machine?".
This paper addresses this question by developing an analytical performance model that captures a two-level cache, coherence cache misses, TLB misses, locking overheads, and contention for memory. Analytical model is combined with results from micro-benchmarking to predict performance on real machines. We have validated our model on two different SMP machines. Our results show that our model effectively captures the impact of memory hierarchy (two-level cache and TLB) as well as the factors that limit parallelism (contention for locks, memory contention, and coherence cache misses). The difference between predicted and measured performance is within 20% in almost all cases. Moreover, the model is quite accurate in predicting the relative performance of the three parallelization techniques.
High-density model for server allocation and placement
Authors: Cameron Craig W. , Low Steven H. , Wei David X.
Published: January 2007

It is well known that optimal server placement is NP-hard. We present an approximate model for the case when both clients and servers are dense, and propose a simple server allocation and placement algorithm based on high-rate vector quantization theory. The key idea is to regard the location of a request as a random variable with probability density that is proportional to the demand at that location, and the problem of server placement as source coding, i.e., to optimally map a source value (request location) to a code-word (server location) to minimize distortion (network cost). This view has led to a joint server allocation and placement algorithm that has a time-complexity that is linear in the number of clients. Simulations are presented to illustrate its performance.
Improving cluster availability using workstation validation
Authors: Heath Taliver , Martin Richard P. , Nguyen Thu D.
Published: January 2007

We demonstrate a framework for improving the availability of cluster based Internet services. Our approach models Internet services as a collection of interconnected components, each possessing well defined interfaces and failure semantics. Such a decomposition allows designers to engineer high availability based on an understanding of the interconnections and isolated fault behavior of each component, as opposed to ad-hoc methods. In this work, we focus on using the entire commodity workstation as a component because it possesses natural, fault-isolated interfaces. We define a failure event as a reboot because not only is a workstation unavailable during a reboot, but also because reboots are symptomatic of a larger class of failures, such as configuration and operator errors. Our observations of 3 distinct clusters show that the time between reboots is best modeled by a Weibull distribution with shape parameters of less than 1, implying that a workstation becomes more reliable the longer it has been operating. Leveraging this observed property, we design an allocation strategy which withholds recently rebooted workstations from active service, validating their stability before allowing them to return to service. We show via simulation that this policy leads to a 70-30 rule-of-thumb: For a constant utilization, approximately 70% of the workstation failures can be masked from end clients with 30% extra capacity added to the cluster, provided reboots are not strongly correlated. We also found our technique is most sensitive to the burstiness of reboots as opposed to absolute lengths of workstation uptimes.
Context-aware TCP/IP
Authors: Williamson Carey , Wu Qian
Published: January 2007

This paper discusses the design and evaluation of CATNIP, a Context-Aware Transport/Network Internet Protocol for the Web. This integrated protocol uses application-layer knowledge (i.e., Web document size) to provide explicit context information to the TCP and IP protocols. While this approach violates the traditional layered Internet protocol architecture, it enables informed decision-making, both at network endpoints and at network routers, regarding flow control, congestion control, and packet discard decisions.The ns-2 network simulator is used to evaluate the performance of the context-aware TCP/IP approach, using a simple network topology and a synthetic Web workload. Simulation results indicate a 10-20% reduction in TCP packet loss using simple endpoint control mechanisms. More importantly, using CATNIP context information at IP routers can produce 20-80% reductions in the mean Web page retrieval times, and 60-90% reductions in the standard deviation of retrieval times.
Case study
Authors: Raje Rajeev R. , Zhong Ming , Wang Tongyu
Published: January 2007

This paper presents a simple three-tier client/server application using two prototypes. The first prototype makes the use of a traditional OOP language, Java. The second prototype uses the Aspect-Oriented Programming (AOP) language AspectJ. The advantages and disadvantages of developing a concurrent system using the AOP paradigm are evaluated, as well as the potential of the AOP paradigm.
From the chairman
Authors: Brown Robert G.
Published: January 2007

This issue of APL Quote-Quad is the first of a series to be published in very rapid order. I would like to take this space to explain exactly what is going on, and provide some background into my thinking on other topics.
APL2 and the internet
Authors: Liebtag David
Published: January 2007

From the very beginning, the APL community has struggled with displaying and printing APL characters. People normally use specialized programs and fonts to edit APL code. The fonts usually work by providing APL characters for code points originally intended for other characters. This technique is troublesome when sharing data with other applications because it often can't be determined reliably whether a particular code point represents an APL character or some other character. To make matters worse, the different APL vendors assign the APL characters to different code points.Recently these problems have arisen on the Internet. People want to use APL on web pages, in email, and in news groups. A variety of schemes have been proposed to address the problem. However, most of these schemes use keywords and require extra effort on the part of the users.With the widespread acceptance of Unicode, it is now easy to use APL characters on the Internet. Simple Mail Transfer Protocol (SMTP), Network News Transfer Protocol (NNTP), and Hypertext Transfer Protocol (HTTP) provide unambiguous, reliable support for Unicode APL characters.The APL2 NETTOOLS workspace provides an HTTP/1.1 conditionally compliant server. This server is Unicode enabled and so provides native support for APL characters in web pages. Using the APL2 Keyboard Handler, APL characters can even be typed in web browsers.
An information retrieval system for software components
Authors: Wood M. , Sommerville I.
Published: January 2007

This paper describes an information retrieval system which is specifically designed to be used for storing and retrieving information about software components. Rather than use a retrieval mechanism which is simply based on keyword descriptions, we have made use of developments in natural language research to represent component information in a form which encodes semantics as well as syntax. We call this the component descriptor frame. The paper describes the basic ideas which underlie our system and describes how it can be used for component information retrieval. An example of the system in use is presented. The version of the system described here has been fully implemented and is now being developed as part of a more general reuse support system.
Navigational aids and learning styles: structural optimal training for computer users
Authors: Cohan Lori A. , Newsome Sandra L.
Published: January 2007

In this highly technical world, computers have become increasingly important in many phases of our lives, including the traditional office. With the influx of computers and automation, many workers previously unfamiliar with sophisticated technology must now learn how to use relatively complex computer systems. For these workers, learning a computer system may be achieved through personal (or class) instruction, reading, direct "hands-on" experience with the computer or some combination of these methods. In order to achieve effective training programs, more attention must be devoted to evaluating learning styles (e.g., active versus passive) and training (e.g., graphical versus textual descriptions).
Development of a three-dimensional auditory display system
Authors: Wenzel Elizabeth M. , Wightman Frederic L. , Foster Scott H.
Published: January 2007

We propose that the most powerful method of auditory cueing takes direct advantage of human perceptual capabilities, providing a dynamic, multidimensional pattern of events which conveys meaning about objects in the spatial world. Applications of such a three-dimensional auditory display involve any context in which the user's situational awareness is critical, particularly when visual cues are limited or absent. Examples include air traffic control displays, advanced teleconferencing environments, and monitoring telerobotic activities in hazardous situations.
Analysis of queues under correlated arrivals with applications to web server performance
Authors: Squillante Mark S. , Woo Baffelly , Zhang Li
Published: January 2007

The complexity of many high-volume Web sites often makes it difficult to mathematically analyze various performance measures. Since these complex behaviors can have a significant impact on performance, it is important to capture them in sufficient detail in the analysis of the corresponding queueing systems.We consider the access logs from a particular class of high-volume Web sites serving dynamic content to obtain a better understanding of the complexities of user request patterns in such environments. Our analysis demonstrates that these arrival patterns exhibit strong dependence structures which can be accurately represented by an arrival process with strong (short-range) correlations, at least for the class of Web sites motivating our study [2]. Based on these results, we develop a methodology for approximating this class of dependent arrival processes by a set of phase-type distributions. Our approach consists of formulating and solving a nonlinear optimization problem that fits a set of dependent stochastic models to approximate the interarrival time patterns from the data, which includes matching the autocorrelation function. To evaluate the effectiveness of our approach, we conduct a large number of statistical tests and experiments showing that our methodology provides an excellent match between the real user request data and the fitted approximate arrival process.Given this dependent arrival process as input, we then derive an exact matrix-analytic analysis of a general multi-server queue under two server queueing disciplines. This analysis yields results that provide significant reductions in the numerical computation required to solve the queueing models. To demonstrate the accuracy of the performance measures obtained under these methods, a large number of experiments were performed and detailed comparisons were made between the sojourn time measures from our analysis and the corresponding measures obtained from simulation of the queueing system under the actual user request data. These results show both sets of performance measures to be in excellent agreement, with relative errors consistently less than 5%, and further demonstrate the robustness of our approach. We also conduct a set of numerical experiments that exploit our matrix-analytic analysis and its computational efficiency, which are then used to establish some important results for multi-server queues under dependent arrival processes. This includes the notion of effective stability where the point at which the mean sojourn time of the queue exceeds a large constant (e.g., 1000) multiplied by the mean service time occurs well before the theoretical stability condition for the queue.Due to space limitations, we simply summarize a subset of our results in this extended abstract. We refer the interested reader to [1] for additional details, references and results.
The
n
th derivative
Authors: Benghorbal Mhenni , Corless Robert M.
Published: January 2007

The following problem is one that many first year calculus students find quite difficult:Given a formula for a function
f
in a variable
x,
find a formula for its
n
th derivative.
Example 1.1:
[1, p. 229] If
f
(
x
) =

x
m
,

(1)then its
n
th derivative is
f

(
n
)

(
x
) =

m-
n
x
m-n
,

(2)where

m-
n
= m

(
m
- 1) (
m
- 2) ⋅⋅⋅ (
m - n
+ 1).The difficulties for students include, first, the discovery of a formula valid for all integers
n
and, second, the proof (for example, by induction) that the formula is correct. Can computer algebra systems do better?It is certain that Macsyma could (we remember commands for infinite Taylor series expansion of elementary functions, and that necessarily involves discovering a correct formula for the
n
th derivative of the input). Currently, Maple cannot---at least, not without help, just with one command, now that the Formal Power Series package in the share library is no longer supported.
The effects of visual proxemic information in video mediated communication
Authors: Grayson David , Coventry Lynne
Published: January 2007

One of the simplest examples of non-verbal communication is that of proximity, i.e. the distance at which conversants stand (or sit) from each other when interacting. This is known to be guided by certain social rules which take into account personal relationships, culture, personality and the purpose of the discussion, violation of which leads to various psychological and behavioural effects.One such effect is persuasion. Sales people will tend to approach customers closer than other business people. Video has in the past been shown to lead to more effective negotiation and bargaining than audio only conditions in experimental tasks. So far though, it remains unknown whether or not similar effects of proximity exist within video-mediated communication --- or indeed even whether or not proximity can be conveyed through video. This study investigates the role of the proxemic information within the video image in a formal persuasion environment using both subjective and objective measures of attitude and behaviour.A simulation of a customer seeking financial advice from an advisor across a live video link had two proxemic conditions --- the image of the advisor appearing either very close or far away. Subjective impressions of both the task and technology were analysed by questionnaire and showed no subjective differences between conditions. Structural analysis of the dialogues however, indicated customers to be more interactive in the close condition. When the advisor appeared close the customer spoke more often, said more, took longer and made more instances of overlapping speech. The similarity between these results and those of familiarity studies are discussed and a hypothesis of perceived close proximity resulting in perceived familiarity is offered.The study shows that proxemic information is preserved in video conferencing and produces effects similar to those of face-to-face interactions but less pronounced. This is explained by the video conveying only visual proxemic information compared to the multimodal information available in face-to-face interaction.
Dynamic analysis for reverse engineering and program understanding
Authors: Stroulia Eleni , Systä Tarja
Published: January 2007

The main focus of program understanding and reverse engineering research has been on modeling the structure of a program by examining its code. This has been the result of the nature of the systems investigated and the perceived goals of the reverse engineering activities. The types of systems under investigation have changed, however, and the maintenance objectives have evolved. Many legacy systems today are object-oriented and component-based. One of the most prominent maintenance objectives is system migration to distributed environments, most notably the World Wide Web, for interoperation with other systems. This new maintenance objective has a great impact on the types of models expected as products of reverse engineering. As the traditional static software analysis techniques keep their valuable role in program comprehension, additional techniques, especially those focusing on run-time analysis of the subject systems, become equally important. In this paper, we focus on the analysis of the system's dynamic behavior, as it pertains to understanding the system's processes and uses. We give an overview of currently used dynamic reverse engineering techniques and identify some challenges yet to be tackled.
Communication skills of technical professionals
Authors: Becker Jack D. , Insley Robert G. , Endres Megan L.
Published: January 2007

The business community has frequently complained about the poor quality of college graduates' communication skills, with information systems and computer science graduates often criticized most severely. The purpose of this research was to investigate and analyze the communication skills of information systems (IS) personnel in terms of current and desired skill levels as perceived by their managers. This paper presents a survey of IS managers which revealed findings concerning: (1) the perceived importance of communication skills to technical professionals, (2) the perceived communication skills levels of these employees as compared to those of employees in nontechnical fields, and (3) the expected levels of communication skills of college graduates in technical fields. For example, the findings reconfirm the need for more communication skills education and training for IS students. The findings and their implications for graduates and professionals in technical fields are discussed.
Project manager's influence tactics and authority
Authors: Rivard Suzanne , Raymond Louis , Bergeron François , Aubin Marie-Claude
Published: January 2007

Ever since firms started using computers for processing their business data, researchers and practitioners have been preoccupied by the successful implementation of information systems (IS). Over the years, researchers have studied several aspects of IS implementation, be it measuring success or developing and testing models that explain IS project success or failure. However, up to now, few IS implementation studies have focused on the role played by the project leader. This paper presents the results of a study of 139 IS project managers. The study examined both the tactics adopted by these project managers to influence people, and their level of decision authority. It then attempted to determine if these two characteristics varied along with the project's organizational structure. The findings of the study point to the mediating role played by project managers' level of decision authority in linking organization structures to influence tactics. While influence tactics used do not vary across project structures, they do so across various levels of decision authority. In turn, the level of authority of project leaders varies across structures and steadily increases on the functional-project continuum. Three influence profiles emerged from the study, namely, the humanist, the political and the authoritarian project manager, providing further interpretation to influence tactics and behavior in an IS development context.
Implementing a small business information resource management course
Authors: Lesjak Dušan
Published: January 2007

This describes the implementation of an Information Resources Management course in a Small Business Management program at the School of Business and Economics, University of Maribor, Slovenia. The aim of the course is to provide students with knowledge and experience to deal with information technology in small business from a managerial perspective. The theoretical part of the course is conducted in a classroom and the practical part is experienced in mentor firms. Thus students have an opportunity to compare, combine and verify "theory" and "practice" instantly and develop capability to transfer the acquired knowledge and skills into practice.
Systems development education and methodology adoption
Authors: Kautz Karlheinz , Pries-Heje Jan
Published: January 2007

The adoption of systems development methodologies has been a subject for research and a topic for discussion for a number of years. One factor, which is often emphasized, is education and training. However, very little research has been focused on the role of formal university education and the dissemination of systems development methodologies. This is the background for this study. It investigates the extent to which a methodology, as well as its encompassing component methods and techniques, taught at the Copenhagen Business School, has been adopted by students and the organizations they are working for. The main result is that very few examples of direct adoption of the methodology taught have been found, but that the training has in general positive influence on the students' utilization of methodologies. The reasons for adoption and non-adoption are discussed based on a grounded theory analysis.
Ethnic diversity in IS
Authors: Payton Fay Cobb , Jackson Cynthia
Published: January 2007

Much attention has been focused on creating diversity in research in the Information Systems (IS) discipline (DeSanctis, 1993; King, 1993; Benbasat and Weber, 1996; Robey, 1996). However, ethnic diversity among the IS faculty has not been a primary research focus. African-, Hispanic- and Native-Americans represent only 4.9% of the more than 24,000 business school professors and only 2.8% of the more than 2,000 Information Systems professors. Many universities attribute this nominal minority representation to the difficulty in finding qualified, tenurable faculty members from these ethnic groups.We replicate the research of Hammond (1995) using the survey and commenter features of a group support system, GroupSystems. In particular, we explore cultural issues that may contribute to the small number of African- and Hispanic-Americans who pursue doctoral degrees in information systems/technology (IS/IT). Our results confirmed some of the cultural differences found in earlier research-such as social isolation and lack of minority faculty mentors. Our results also identified family responsibilities and the need to give back to ethnic communities as important cultural issues affecting minorities' IS/IT doctoral students.
Discovery in multi-attribute data with user-defined constraints
Authors: Perng Chang-Shing , Wang Haixun , Ma Sheng , Hellerstein Joseph L.
Published: January 2007

There has been a growing interest in mining frequent itemsets in relational data with multiple attributes. A key step in this approach is to select a set of attributes that group data into transactions and a separate set of attributes that labels data into items. Unsupervised and unrestricted mining, however, is stymied by the combinatorial complexity and the quantity of patterns as the number of attributes grows. In this paper, we focus on leveraging the semantics of the underlying data for mining frequent itemsets. For instance, there are usually taxonomies in the data schema and functional dependencies among the attributes. Domain knowledge and user preferences often have the potential to significantly reduce the exponentially growing mining space. These observations motivate the design of a user-directed data mining framework that allows such domain knowledge to guide the mining process and control the mining strategy. We show examples of tremendous reduction in computation by using domain knowledge in mining relational data with multiple attributes.
A real-time assistive computer interface for users with motor disabilities
Authors: Barreto A. B. , Scargle S. D. , Adjouadi M
Published: January 2007

This study introduces the design of an integrated assistive real-time system developed as an alternate input device to computers that can be used by individuals with severe motor disabilities. An assistive technology device as defined by the Assistive Technology Act of 1998 is "any item, piece of equipment, or product system, whether acquired commercially, modified, or customized, that is used to increase, maintain, or improve the functional capabilities of individuals with disabilities". The proposed real-time system design utilizes electromyographic (EMG) biosignals from cranial muscles and electroencephalographic (EEG) biosignals from the cerebrum's occipital lobe, which are transformed into controls for two-dimensional (2-D) cursor movement, the Left-Click (Enter) command, and an ON/OFF switch for the cursor-control functions. This HCI system classifies biosignals into "mouse" functions by applying amplitude thresholds and performing power spectral density (PSD) estimations on discrete windows of data, Spectral power summations are aggregated over several frequency bands between 8 and 500 Hz and then compared to produce the correct classification. The result is an affordable DSP-based system that, when combined with an on-screen keyboard, enables the user to fully operate a computer without using any extremities.
Interfacing users with very severe mobility restrictions with a semi-automatically guided wheelchair
Authors: Abascal Julio , Cagigas Daniel , Garay Nestor , Gardeazabal Luis
Published: January 2007

TetraNauta is an on-going R&D project aimed to develop a controller for standard electric-powered wheelchairs that permits users with very severe mobility restrictions (such as people with tetraplegy) to easily navigate in closed environments (home, hospital, school, etc.). This project intends to design a non-expensive guidance system to help this kind of users to drive the wheelchair with the minimum effort, but maintaining the user as active as possible. For this reason the design of the user interface is a key factor. Some characteristic of this interface can be taken as a workbench for the design of more complex and security critical mobile systems.
Using a cyberlink mental interface for relaxation and controlling a robot
Authors: Doherty Eamon , Stephenson Gary , Engel Walter
Published: January 2007

This paper discusses a brain computer interface technology that allows disabled persons with physical and/or mental disabilities to control a computer to play games and communicate at a basic level. It was interesting that a head administrator at the institution where the research took place noted that it was her opinion that the people who took part in the research seemed more relaxed, a little more self confident, and many appeared to really reduce their involuntary movements during game playing. The researcher asked a group of people to relax at the beginning and end of each test session over a period of approximately a year. A data capture program using a FFT (fast fourier transform) averaged the amplitude of EMG (Electromyograph) signal waves over five seconds to measure relaxation. The data was tabulated by and the results are displayed. The Cyberlink target audience was found to be intelligent persons with no other method of operating input devices or controlling their environment. It was discovered during formal interviews and during experiments that quadriplegic persons wished to use the Cyberlink not only for communication and recreation but to also power a robotic arm much as one uses a prosthetic arm.
The need for a 'universal accessibility' engineering tool
Authors: Lindenberg J. , Neerincx M. A.
Published: January 2007

The countries of the European Union generally want to enhance self-support for the elderly and disabled and consequently strive for accessibility of 'mainstream' Information and Communication Technology (ICT) for these inhabitants. The 'universal accessibility' approach is advocated as a possibility to include all user groups in the software development process.The European Union supports research in this area, for example by funding the project Assessing the Awareness of the Design for All Approach (AADAA consortium, 1998).However, the 'universal accessibility' approach is not as widely spread in the design community, as it should be. Several reasons have been identified. First, the phenomenon that 'universal accessibility' products are perceived as dull by the designers creates serious problems for the acceptance of the 'universal accessibility' paradigm. This might, however, be a self-fulfilling prophecy. Second, the cost of involving elderly and disabled users in software development can be higher than for involving the rest of the population. On the other hand, a broader perspective comprises also the advantages of the 'universal accessibility' approach: The involvement of elderly in the design process often results in better products for all kind of users so that the overall utility of this approach is high (Gleiss et al., 1995). Furthermore, the number of potential users of the 'universal accessible' product also increases so it might very well be a good investment. Third, the extra constraints on design possibilities are another objection. However, it could be that the constraints force the designers to be creative, bringing about new ideas that enrich the total design space (Newell & Gregor, 1997). In sum, the three problems of dullness, design costs and design constraints can be solved by evoking positive attitudes, widened cost-benefit analyses and creative design solutions. However, to realise 'universal accessibility', the corresponding human factors knowledge should be incorporated into the design practice. Currently, designers take insufficiently account of human-factors knowledge on elderly and disabled (Neerincx, 1998). This paper provides a cognitive engineering approach to solve this problem.
Computing the minimal telescoper for sums of hypergeometric terms
Authors: Le H. Q.
Published: January 2007

Let
T
(
n, k
) be a hypergeometric term of
n
and
k.
We present in this paper an algorithm to construct the minimal telescoper for
U
(
n, k
) = ∑

m=b

n
-1

T
(
m, k
),
b
ε ℤ, if it exists. We show a Maple implementation of this method and discuss the problem of finding closed forms of definite sums of
U
(
n, k
).
Solving systems of algebraic equations
Authors: Lazard Daniel
Published: January 2007

Let
f
1
,…,

f
k

be
k
multivariate polynomials which have a finite number of common zeros in the algebraic closure of the ground field, counting the common zeros at infinity. An algorithm is given and proved which reduces the computations of these zeros to the resolution of a single univariate equation whose degree is the number of common zeros. This algorithm gives the whole algebraic and geometric structure of the set of zeros (multiplicities, conjugate zeros,…). When all the polynomials have the same degree, the complexity of this algorithm is polynomial relative to the generic number of solutions.
Collaborative environmental education using distributed virtual environment accessible from real and virtual worlds
Authors: Okada Masaya , Tarumi Hiroyuki , Yoshimura Tetsuhiko , Moriya Kazuyuki
Published: January 2007

We have designed and implemented a support system for collaborative environmental education, DigitalEE, which realizes distributed virtual environment accessible from real and virtual worlds. This system introduces the following diverse features into environmental education: global arguments supported by the Internet, giving learners pseudo experiences by virtual reality, supplementing real natural experiences by augmented reality, and giving learners experts' valuable knowledge by distance education. Shared virtual space in the distributed virtual environment is "3D virtual nature", which is a VRML world representing the real nature. Learners learning through direct experiences can enter the 3D virtual nature from the real world with mobile computers, whereas experts and other participants can enter the 3D virtual nature from distant locations with their personal computers. People throughout the world can communicate with each other while sharing the same place virtually between real and virtual worlds. Learners' observation, experts' knowledge, and other participants' information are continuously accumulated in the shared 3D virtual nature as VRML objects and web pages, and the world is being updated dynamically in the learning process. With these ideas, DigitalEE realizes a new style of environmental education such as collaborative outdoor learning supported by knowledgeable experts throughout the world and interactive virtual tours to inaccessible natural environment.
The active collections framework
Authors: Raj Rajendra K.
Published: January 2007

Sharing enterprise data consistently in near-real-time is a common computing problem increasingly faced by large distributed enterprises today. Enterprise data is typically stored in persistent data stores such as relational databases, and enterprise-wide distributed applications continually retrieve, create, modify, or delete this data. The Active Collections Framework (ACF) is proposed as a mechanism to solve this problem. ACF provides uniform application access to both enterprise data and subsequent data changes through the concept of an
Active Collection.
This paper describes the basic features of ACF, illustrates its usefulness in building enterprise applications, and briefly discusses ACF implementation issues.
Interest made simple with arrays
Authors: Brown Richard L. W.
Published: January 2007

A better financial calculator
Students of the mathematics of finance seem to be comfortable using calculators to evaluate formulas or numerical expressions. They are typically much less comfortable writing programs in BASIC (or C or Java etc.) even in situations where the calculator solution is tedious and a short program would do the job efficiently. Spreadsheet models, with an emphasis on formulas as opposed to programs, are quite a reasonable and intuitive tool. But spreadsheet formulas seem to be about cells rather than money, time, and interest rates.The ideal tool would be a better calculator. APL and J can be used in calculator mode and therefore should be marketable to students as advanced calculators ideally suited to financial mathematics. This is especially true now that APL and J can be run on a variety of palm-sized computers.This paper presents a few ideas on how students might use J in the mathematics of finance. The emphasis is on using J as a calculator that has lots of memory and can store and compute with arrays. Therefore data will be entered and expressions evaluated but no programs will be presented in the classroom. (However, two utility programs and a few names for J primitives will be used as noted in the next subsection.)
J Definitions used in what follows
The J examples below are presented in the plain Courier font. Certain definitions are assumed and these are displayed in
Courier italics.
The definitions of these italicized functions are given in the
Appendix
at the end of the paper. In particular, frequent use is made of a dollar format function
Df
to display numbers in dollar currency format. When dates are part of the input data, the
dayno
function can be used to compute a day number.All examples in this paper (except for Example 7, which uses the sparse arrays of J version 4.04) can be done with versions of J going back (at least) to J FreeWare, version 3.02.
Noun phrase chunking with APL2
Authors: Manandhar Suresh , Alfonseca Enrique
Published: January 2007

The identification of phrases in a sentence can be useful as a pre-processing step before attempting the full parsing. There is already much literature about finding simple non-recursive non-overlapping Noun Phrases. We have modified the learning paradigm CLOG [4] to produce transformation lists, and we arrived to several interesting conclusions about Noun Phrase chunking. IBM APL2 was used to build a prototype that was later rewritten in C++ for performance purposes.
Visual representation of document-oriented information on the web
Authors: Zlobin Dmitriy , Roudometkine Alexei
Published: January 2007

Ever increasing volumes of data motivate us to find new processing and storage methods for provide quick retrieval of information. Users of conventional text-based search engines have faced the problem of digging through thousands of hits returned from keyword searches. There are alternative ways of storing and searching document-related data; these techniques support more direct and simplified document searches guiding the user towards fewer but higher quality selections.One such method is known as WebSOM, Web Self-Organizing Maps, which are based on Kohonen's neural network approach and modern graphical user interfaces. We will show, through the use of APL with this and other methods of information analysis, how to visualize this type of search.
Variable precision arithmetic
Authors: Schonfelder J. L.
Published: January 2007

This paper describes the design and development of a software package supporting variable precision arithmetic as a semantic extension to the core FORTRAN language. The working precision of the arithmetic supported by this package can be dynamically and arbitrarily variable. The facility exploits the data-abstraction capabilities of Fortran 95 and allows the operations to be used elementally with array operands as well as with scalars.The number system is defined in such a way as to be closed under all of the basic operations of normal arithmetic; no program-terminating numerical exceptions can occur. Precision loss situations like underflow and overflow are handled by defining special value representations that preserve as much of the numeric information as is practical and the operation semantics are defined so that these exceptional values propagate as appropriate to reflect this loss of information.The number system uses an essentially conventional variable precision floating-point representation. Where operations can be performed exactly within the currently-set working precision limit, the excess trailing zero digits are not stored, nor do they take part in future operations. This is both economical in storage and improves efficiency. By judiciously managing the working precision, arithmetic operations that are potentially exact can be performed exactly.
A view from the SIGCPR conference
Authors: Niederman Fred , Moore Jo Ellen , Yager Susan E.
Published: January 2007

Previous research on computer personnel, or the "people part" of the computer technology equation, has stimulated understanding of the interaction between people and technology. This paper presents the results of quantitative and qualitative analysis of proceedings from the 1991 through 1999 annual conference of the Association for Computing Machinery's Special Interest Group on Computer Personnel Research. The study develops a framework defining the domain of management information systems personnel research, summarizes lessons learned, organizes and presents research questions from the past decade's research, and identifies exemplary research streams that provide support for expanding theory and application knowledge in this field. While the continual evolution of technology sets the stage for future research, the need for development of new knowledge in several specific areas is suggested.
An on-demand minimum energy routing protocol for a wireless ad hoc network
Authors: Doshi Sheetalkumar , Bhandare Shweta , Brown Timothy X
Published: January 2007

A minimum energy routing protocol reduces the energy consumption of the nodes in a wireless ad hoc network by routing packets on routes that consume the minimum amount of energy to get the packets to their destination. This paper identifies the necessary features of an
on-demand
minimum energy routing protocol and suggests mechanisms for their implementation. We highlight the importance of efficient caching techniques to store the minimum energy route information and propose the use of an 'energy aware' link cache for storing this information. We compare the performance of an
on-demand
minimum energy routing protocol in terms of energy savings with an existing
on-demand
ad hoc routing protocol via simulation. We discuss the implementation of Dynamic Source Routing (DSR) protocol using the Click modular router on a real life test-bed consisting of laptops and wireless Ethernet cards. Finally we describe the modifications we have made to the DSR router to make it energy aware.
Pro-active route maintenance in DSR
Authors: Qin Liang , Kunz Thomas
Published: January 2007

Most existing on-demand mobile ad hoc network routing protocols continue using a route until a link breaks. During the route reconstruction, packets can be dropped, which may cause significant throughput degradation. In this paper, we add a link breakage prediction algorithm to the Dynamic Source Routing (DSR) protocol. The mobile node uses signal power strength from the received packets to predict the link breakage time, and sends a warning to the source node of the packet if the link is soon-to-be-broken. The source node can perform a pro-active route rebuild to avoid disconnection. Experiments demonstrate that adding link breakage prediction to DSR can significantly reduce the total number of dropped data packets (by at least 20%). The tradeoff is an increase in the number of control messages by at most 33.5%. We also found that the pro-active route maintenance does not cause significant changes in average packet latency and average route length.
Wireless media access control for highly mobile information servers
Authors: Mok Kui W. , Lim Alvin S.
Published: January 2007

Innovations of modern digital radio technology has enabled many large mobile and distributed information systems, such as inventory tracking systems, to provide readily accessible voice and data services to end users despite mobility of data servers. These systems often contain components that are equipped with radio frequency identification (RFID) tags and interrogators for wireless connectivity. However, there are usually large number of these tagged items in these systems that are highly mobile. The wireless connections among them are also prone to failure. In this paper, we evaluate and compare the performance of two RF tag data access protocols in a single channel per cell implementation: slotted ALOHA Time Division Multiple Access (slotted ALOHA/TDMA) and Direct Sequence Code Division Multiple Access (DS/CDMA).We use a discrete event simulation model to study the impact of these protocols on data service under a diversity of highly mobile operating conditions. Mobile conditions are captured separately by various levels of burst error, uplink and downlink disconnections, and tag population. The results show that performance of DS/CDMA dominates in all mobile conditions. In the most general cases, DS/CDMA outperforms slotted ALOHA/TDMA by 1.5 times faster message time. DS/CDMA is particularly superior in the case of pure uplink disconnections. For burst error and pure downlink disconnections, DS/CDMA renders as much as 2.0 times and 4.5 times faster message time respectively.
Saving portable computer battery power through remote process execution
Authors: Rudenko Alexey , Reiher Peter , Popek Gerald J. , Kuenning Geoffrey H.
Published: January 2007

We describe a new approach to power saving and battery life extension on an untethered laptop through wireless remote processing of power-costly tasks. We ran a series of experiments comparing the power consumption of processes run locally with that of the same processes run remotely. We examined the trade-off between communication power expenditures and the power cost of local processing. This paper describes our methodology and results of our experiments. We suggest ways to further improve this approach, and outline a software design to support remote process execution.
A location management technique to support lifelong numbering in personal communications services
Authors: Lam Derek , Cui Yingwei , Cox Donald C. , Widom Jennifer
Published: January 2007

This paper presents a novel
location management technique,
HOPPER, that is designed to support in a scalable and efficient manner non-geographical (lifelong) personal numbers in Personal Communications Services (PCS). Performance comparisons between our scheme and previous schemes are derived from large scale simulations using a realistic traffic modeling framework for the ten largest cities of the United States. Results show that, in addition to inherently providing nongeographical numbers, the proposed scheme significantly improves lookup performance and requires relatively little database access and network signaling resources.
Mobile ad hoc networking and the IETF
Authors: Macker Joseph P. , Corson M. Scott
Published: January 2007

This article is the first in a series intended to chronicle the status of work underway within the Mobile Ad hoc NETworks (MANET) Working Group of the Internet Engineering Task Force (IETF). This article provides a short history and high-level, conceptual tutorial of MANET technology. We present an overview of the working group's vision and charter, and a glimpse into a technical architecture under consideration for achieving this vision.
RDRN
Authors: Sánchez Ricardo J. , Evans Joseph B. , Minden Gary J. , Frost Victor S. , Shanmugan K. Sam
Published: January 2007

This paper reports on the initial implementation of an experimental wireless ATM network architecture called RDRN (Rapidly Deployable Radio Network). The RDRN architecture consists of two types of transportable nodes, remote nodes (RNs) and edge nodes (ENs), which utilize GPS-derived location information to rapidly configure themselves into a high capacity wireless network operating at 1--10 Mb/s over distances as far as 10 kilometers. The initial prototype has been deployed and early experiments have been conducted to validate hardware, software, and protocol design and implementation. In addition to describing the RDRN architecture and protocols, this paper details experiences at the DARPA GLOMO '97 demonstration of the RDRN project.
RMDP
Authors: Rizzo Luigi , Vicisano Lorenzo
Published: January 2007

In this paper we present a Reliable Multicast data Distribution Protocols (RMDP), and discuss its performance. The protocol is based on the use of FEC techniques to drastically reduce the impact of independent losses for different receivers, which make ARQ-based protocols perform very poorly as the number of receivers grows. The protocol is well-suited to the use with mobile equipment because of its simplicity, robustness to losses, moderate demand for feedback, and scalability.