bluuebunny/crossref_metadata_2025 huggingface dataset:
Incentives for content availability in memory-less peer-to-peer file sharing systems
Authors: Antoniadis Panayotis , Courcoubetis Costas , Strulo Ben
Published: January 2007

In this paper we address the issue of content availability in p2p file sharing systems. Content availability is a public good: the copying of a file by one peer does not prevent another peer also from copying it; but contributing files to the common pool is costly. The asymptotic analysis of certain public good models for p2p file sharing suggests that when the aim is to maximize social welfare, a fixed contribution scheme in terms of the number of files shared per unity of time can be asymptotically optimal as the number of participants
n
grows to infinity. However, the enforcement of such an incentive scheme is not straightforward in a realistic p2p system, where no trusted software or central entity accounting for peers' transactions can be assumed and peers are free to change their identity with no cost. We present a realistic version of the fixed contribution scheme, which does not require the use of system memory but relies only on the time peers are consuming resources to ensure that they contribute adequately. We describe the functionality that should be supported for enforcement and discuss the additional incentive issues that arise in this context, proposing some practical solutions to address them. We also formulate a suitable economic model to estimate the efficiency-loss of the proposed mechanism (compared to the one achieved using the theoretically optimal schemes under complete and incomplete information) and provide some insights for the correct tuning of its basic parameters. Our first results indicate that the proposed mechanism constitutes a good compromise between economic efficiency and implementability and should lead to some interesting and practical solutions for providing incentives for content availability in p2p systems.
A non-manipulable trust system based on EigenTrust
Authors: Abrams Zoë , McGrew Robert , Plotkin Serge
Published: January 2007

A fundamental consideration in designing successful trust scores in a peer-to-peer system is the self-interest of individual peers. We propose a strategyproof partition mechanism that provides incentives for peers to share files, is non-manipulable by selfish interests, and approximates trust scores based on EigenTrust. The basic idea behind the partition mechanism is that the peers are partitioned into peer groups and incentives are structured so that a peer only downloads from peers in one other peer group. We show that the total error in the trust values decreases exponentially with the number of peer groups. In addition to theoretically guaranteeing non-manipulability, in practice our trust system performs nearly as well as EigenTrust and has better load-balancing properties.
Challenges for efficient communication in underwater acoustic sensor networks
Authors: Akyildiz Ian F. , Pompili Dario , Melodia Tommaso
Published: January 2007

Ocean bottom sensor nodes can be used for oceanographic data collection, pollution monitoring, offshore exploration and tactical surveillance applications. Moreover, Unmanned or Autonomous Underwater Vehicles (UUVs, AUVs), equipped with sensors, will find application in exploration of natural undersea resources and gathering of scientific data in collaborative monitoring missions. Underwater acoustic networking is the enabling technology for these applications. Underwater Networks consist of a variable number of sensors and vehicles that are deployed to perform collaborative monitoring tasks over a given area.In this paper, several fundamental key aspects of underwater acoustic communications are investigated. Different architectures for two-dimensional and three-dimensional underwater sensor networks are discussed, and the underwater channel is characterized. The main challenges for the development of efficient networking solutions posed by the underwater environment are detailed at all layers of the protocol stack. Furthermore, open research issues are discussed and possible solution approaches are outlined.
Research challenges for wireless sensor networks
Authors: Stankovic John A.
Published: January 2007

Wireless sensor networks (WSN) are currently receiving significant attention due to their unlimited potential. However, it is still very early in the lifetime of such systems and many research challenges exist. In this brief article, I concentrate on six key research challenges for wireless sensor networks. I conclude with a brief mention of a number of other research challenges that must be met before WSN become pervasive.
FPGA based CPU instrumentation for hard real-time embedded system testing
Authors: Fryer Richard
Published: January 2007

The addition of system instrumentation features have been sporadically incorporated into processor architectures over the last several decades. Particular emphasis areas of high performance, embedded and real-time computing are reviewed in terms of software and hardware measurements and approaches representing active research directions. A novel approach is described that may be readily used with recent advances in Field Programmable Gate Array technology using embedded processors. The approach and preliminary results are described using a Xilinx device with a MicroBlaze
TM
32 bit architecture. Some system level problems are outlined and examined.
AGCMemory
Authors: Basanta-Val Pablo , García-Valls Marisol , Estévez-Ayres Iria
Published: January 2007

The region-based memory model of The Real-time Specification for Java (RTSJ) is quite rigid, and it complicates the development of reusable predictable software for large-scale systems. In this paper, we propose an extension to the region model of the RTSJ called AGCMemory (Acyclic Garbage Collected Memory). This extension enables the transparent destruction of floating garbage created during the execution of Java methods. The integration within the memory model of the RTSJ and its automatic memory management algorithm, based on run-time barriers, are described.
Embedded systems education
Authors: Jackson David Jeff , Caspi Paul
Published: January 2007

In this paper we present the summary of and results from the 2005 Workshop on Embedded Systems Education (WESE2005). This workshop was held in conjunction with EMSOFT 2005, the leading conference for research in embedded systems software. The workshop focused on presenting experiences in embedded systems and embedded software education. Workshop sessions included a diverse set of international presenters leading discussions on embedded systems curricula and content; teaching experiences; and labs and platforms used in embedded systems education. A summary panel discussion concluded the workshop.
Demand-driven curriculum for embedded system software in Korea
Authors: Pak Suehee , Rho Eunha , Chang Juno , Kim Moon Hae
Published: January 2007

This paper describes how Korean Government has designed and driven the innovation of undergraduate curriculums to meet increasing industrial demand for quality IT experts in the computer-software field. The computer-software field has been categorized into five specialized areas, tracks. The embedded system software area is one among them. Educational contents (including track curriculums, detailed syllabuses, and class materials) have been designed and constructed for the tracks. First, a curriculum development methodology is described, which is used to develop curriculums in the computer-software field. Next, artifacts for the embedded software system track produced in the process are described. By applying iterative and incremental principles of the methodology, all artifacts will be continuously updated and constantly upgraded as related technologies progress rapidly.
A system for automatic testing of embedded software in undergraduate study exercises
Authors: Legourski Voin , Trödhandl Christian , Weiss Bettina
Published: January 2007

As student numbers in embedded systems lab courses increase, it becomes more and more time-consuming to verify the correctness of their homework and exam programs. Automatic verification can vastly improve the speed and quality of such tests. This paper describes a system that can carry out black-box tests to verify whether the embedded software running on a target system meets predefined requirements. To this aim, we employ a special test board using an ATmega128 microcontroller which is connected to both the target system and to a host computer. Tests can be selected and started remotely, the results are presented to the user on the host. Monitoring and control via Internet is also easily possible. A special meta-language is used to describe the correct behavior of the tested program, and this description is compiled and downloaded to the test system via a standard RS-232 interface, where the test is executed. The same interface is used to control the tests and for transfer of data and end results.
Experiences teaching an FPGA-based embedded systems class
Authors: Edwards Stephen A.
Published: January 2007

I describe a two-year-old embedded systems design course I teach at Columbia University. In it, the students learn low-level C programming and VHDL coding to design and implement a project of their own choosing. The students implement their projects using Xilinx FPGAs and tools running on Linux workstations.The main challenges the students face are understanding and complying with complex and often poorly-documented interfaces and protocols, personal time management, and teamwork. While all real-world challenges, this class is often the first time the students encounter them, which makes the class quite challenging, but very practical.In this paper, I describe the structure of the class, the configuration of our teaching laboratory, some of the more successful projects, and give suggestions to instructors wishing to implement the class elsewhere.
Diverse hardware platforms in embedded systems lab courses
Authors: Salewski Falk , Wilking Dirk , Kowalewski Stefan
Published: January 2007

Traditional methods for teaching the design of embedded systems usually deal with either a hardware or a software view of the system. In computer science it is mostly the software view. The hardware issues taught mostly deal with CPU based systems only and seldom with reconfigurable hardware. We recommend having a more general view at embedded systems in the way that it is always a programmable hardware platform (CPU based or reconfigurable hardware) which has to be programmed in a suitable programming language. In this context we offer a lab course where students should get familiar with different hardware platforms used in embedded systems. They should solve the same task both with a CPLD and a microcontroller each in order to clarify the differences between the two implementations. In this paper our experiences in this field of embedded systems education are described as well as our plans to continue.
Design patterns and Fortran 90/95
Authors: Markus Arjen
Published: January 2007

In the literature on object oriented programming (OO), design patterns are a very popular subject. Apart from any hype that may be connected to the concept, they are supposed to help you look at a programming problem and come up with a robust design for its solution. The reason design patterns work is not that they are something new, but instead that they are time-honoured, well-developed solutions.I will not repeat the story about architectural design patterns and Christopher Alexander who recognised their potential. Instead I will try to explain how these (software) design patterns can be used in setting up Fortran 90/95 programs, despite the "fact" that Fortran 90/95 lacks certain OO features, such as inheritance and polymorphism. It may not be stressed in all OO literature, but design patterns help you find solutions that do not necessarily involve inheritance or polymorphism (cf. Shalloway and Trott, 2002).Design patterns come by fancy names such as the Adapter pattern or the Decorations pattern and explaining what they are and how to use them is best done via a few examples.
Localization of off-the-shelf mobile devices using audible sound
Authors: Lopes Cristina V. , Haghighat Amir , Mandal Atri , Givargis Tony , Baldi Pierre
Published: January 2007

Sound source localization will play a major role in the new location-aware applications envisioned in Ubiquitous Computing. We describe the design and performance of three architectures and corresponding protocols that use a variation of the Time-of-Flight method for localizing three different kinds of devices, namely 802.11-enabled PDAs, 3G cell phones, and PDAs without network connectivity. The quantitative assessment is based on the deployment made with 6 sensors in, a 20x9m room, sewing over 10,000 localization requests. Our experiments indicate that all architectures achieve localization within 70cm of the actual position 90% of the time. The accuracy is further improved to 40cm 90% of the time when geometric factors are taken into consideration. The effects of noise and obstructions are also analyzed. Within 1m localization error realistic noise degrades the accuracy by 6 to 10%. The presence of obstacles, such as humans and cement columns, has no observable effect on the performance.
Challenges in managing dependable data systems
Authors: Keeton Kimberly , Merchant Arif
Published: January 2007

Recent work shows how to automatically design storage systems that meet performance and dependability requirements by appropriately selecting and configuring storage devices, and creating snapshot, remote mirror, and traditional backup copies. Although this work represents a solid foundation, users demand an even higher level of functionality: the ability to cost-effectively manage data according to application-centric (or better, business process-centric) performance, dependability and manageability requirements, as these requirements evolve over the data's lifetime. In this paper, we outline several research challenges in managing dependable data systems, including capturing users' high-level goals; translating them into storage-level requirements; and designing, deploying, and analyzing the resulting data systems.
Data streaming algorithms for estimating entropy of network traffic
Authors: Lall Ashwin , Sekar Vyas , Ogihara Mitsunori , Xu Jun , Zhang Hui
Published: January 2007

Using entropy of traffic distributions has been shown to aid a wide variety of network monitoring applications such as anomaly detection, clustering to reveal interesting patterns, and traffic classification. However, realizing this potential benefit in practice requires accurate algorithms that can operate on high-speed links, with low CPU and memory requirements. In this paper, we investigate the problem of estimating the entropy in a streaming computation model. We give lower bounds for this problem, showing that neither approximation nor randomization alone will let us compute the entropy efficiently. We present two algorithms for randomly approximating the entropy in a time and space efficient manner, applicable for use on very high speed (greater than OC-48) links. The first algorithm for entropy estimation is inspired by the structural similarity with the seminal work of Alon et al. for estimating frequency moments, and we provide strong theoretical guarantees on the error and resource usage. Our second algorithm utilizes the observation that the performance of the streaming algorithm can be enhanced by separating the high-frequency items (or elephants) from the low-frequency items (or mice). We evaluate our algorithms on traffic traces from different deployment scenarios.
Automatic logging of operating system effects to guide application-level architecture simulation
Authors: Narayanasamy Satish , Pereira Cristiano , Patil Harish , Cohn Robert , Calder Brad
Published: January 2007

Modern architecture research relies heavily on application-level detailed pipeline simulation. A time consuming part of building a simulator is correctly emulating the operating system effects, which is required even if the goal is to simulate just the application code, in order to achieve functional correctness of the application's execution. Existing application-level simulators require manually hand coding the emulation of each and every possible system effect (e.g., system call, interrupt, DMA transfer) that can impact the application's execution. Developing such an emulator for a given operating system is a tedious exercise, and it can also be costly to maintain it to support newer versions of that operating system. Furthermore, porting the emulator to a completely different operating system might involve building it all together from scratch.In this paper, we describe a tool that can automatically log operating system effects to guide architecture simulation of application code. The benefits of our approach are: (a) we do not have to build or maintain any infrastructure for emulating the operating system effects, (b) we can support simulation of more complex applications on our application-level simulator, including those applications that use asynchronous interrupts, DMA transfers, etc., and (c) using the system effects logs collected by our tool, we can deterministically re-execute the application to guide architecture simulation that has reproducible results.
Understanding the management of client perceived response time
Authors: Olshefski David , Nieh Jason
Published: January 2007

Understanding and managing the response time of web services is of key importance as dependence on the World Wide Web continues to grow. We present
Remote Latency-based Management
(RLM), a novel server-side approach for managing pageview response times as perceived by remote clients, in real-time. RLM passively monitors server-side network traffic, accurately tracks the progress of page downloads and their response times in real-time, and dynamically adapts connection setup behavior and web page content as needed to meet response time goals. To manage client perceived pageview response times, RLM builds a novel event node model to guide the use of several techniques for manipulating the packet traffic in and out of a web server complex, including fast SYN and SYN/ACK retransmission, and embedded object removal and rewrite. RLM operates as a stand-alone appliance that simply sits in front of a web server complex, without any changes to existing web clients, servers, or applications. We have implemented RLM on an inexpensive, commodity, Linux-based PC and present experimental results that demonstrate its effectiveness in managing client perceived pageview response times on transactional e-commerce web workloads.
The Erlang model with non-poisson call arrivals
Authors: Bonald Thomas
Published: January 2007

The Erlang formula is known to be insensitive to the holding time distribution beyond the mean. While calls are generally assumed to arrive as a Poisson process, we prove that it is in fact sufficient that users generate
sessions
according to a Poisson process, each session being composed of a random, finite number of calls and idle periods. A key role is played by the retrial behavior in case of call blocking. We illustrate the results by a number of examples.
On the way to a distributed systems calculus
Authors: Fidler Markus , Schmitt Jens B.
Published: January 2007

Network calculus is a min-plus system theory which facilitates the efficient derivation of performance bounds for networks of queues. It has successfully been applied to provide end-to-end quality of service guarantees for integrated and differentiated services networks. Yet, a true end-to-end analysis including the various components of end systems as well as taking into account mid-boxes like firewalls, proxies, or media gateways has not been accomplished so far. The particular challenge posed by such systems are transformation processes, like data processing, compression, encoding, and decoding, which may alter data arrivals drastically. The heterogeneity, which is reflected in the granularity of operation, for example multimedia applications process video frames which, however, are represented by packets in the network, complicates the analysis further. To this end this paper evolves a concise network calculus with scaling functions, which allow modelling a wide variety of transformation processes. Combined with the concept of packetizer this theory enables a true end-to-end analysis of distributed systems.
Flexible time-windows for advance reservation in LambdaGrids
Authors: Kaushik Neena R. , Figueira Silvia M. , Chiappari Stephen A.
Published: January 2007

Advance-reservation requests are an essential feature of LambdaGrids, where resources may need to be co-allocated at pre-determined times. In this paper, we discuss unconstrained advance reservations, which use flexible time-windows to lower blocking probability and, consequently, increase resource utilization. We claim and show using simulations that the minimum window size, which theoretically brings the blocking probability to 0, in a first-come-first-served advance reservation model without time-slots, equals the waiting time in a queue-based on-demand model. We also show, with simulations, the window sizes, which bring the blocking probability to its minimum, for an advance reservation model with time-slots.
Applying architectural vulnerability Analysis to hard faults in the microprocessor
Authors: Bower Fred A. , Hower Derek , Yilmaz Mahmut , Sorin Daniel J. , Ozev Sule
Published: January 2007

In this paper, we present a new metric, Hard-Fault Architectural Vulnerability Factor (H-AVF), to allow designers to more effectively compare alternate hard-fault tolerance schemes. In order to provide intuition on the use of H-AVF as a metric, we evaluate fault-tolerant level-1 data cache and register file implementations using error correcting codes and a fault-tolerant adder using triple-modular redundancy (TMR). For each of the designs, we compute its H-AVF. We then use these H-AVF values in conjunction with other properties of the design, such as die area and power consumption, to provide composite metrics. The derived metrics provide simple, quantitative measures of the cost-effectiveness of the evaluated designs.
Jordan algebras arising from intermolecular recombination
Authors: Bremner Murray R.
Published: January 2007

We use computer algebra to show that a linearization of the operation of intermolecular recombination from theoretical genetics satisfies a nonassociative polynomial identity of degree 4 which implies the Jordan identity. We use the representation theory of the symmetric group to decompose this new identity into its irreducible components. We show that this new identity implies all the identities of degree ≤ 6 satisfied by intermolecular recombination.
A dance of rounds
Authors: Benkhard J. Phillip
Published: January 2007

Two different methods of getting sums of rounded numbers to add up to the rounded sum are discussed. The case of cascaded rounding, in which each number is replaced by a set of numbers to be rounded to a conforming sum, with the sum of the conforming sums itself conforming to the sum of the whole, is covered. Geometric properties of are reviewed.
Extending structure, type, and expression in APL2
Authors: Benkhard J. Phillip
Published: January 2007

The two principal directions of
APL
today are discussed in the light of recent standards committee meetings. The approach often taken to an extended standard was to place features of both dialects into a work space and force them to work; this might be called a top down approach with hammer. Herein
APL2,
considered as a representative of nested array systems, is assumed as a base. A growth path is described toward a system which includes features similar to some found in boxed array systems. A parallel discussion beginning with a boxed system and extending toward nested arrays would be welcome. Perhaps working toward a common goal could provide more inspiration than striving to preserve pieces of the past.
Pure functions in APL and J
Authors: Cherlin Edward
Published: January 2007

Any expression in combinatory logic made up of combinators and variables can be abstracted into a pure combinator expression applied to a sequence of variables. Because there are great similarities between combinators and certain APL operators, a similar result obtains in many APL dialects. However, rewriting arbitrary APL expressions as pure functions requires new operators, not provided as primitives by any dialect. This paper defines functional completeness, gives a construction for achieving it, proves a conjecture of Kenneth Iverson that J is functionally complete, and shows how closely the major APL dialects have approached these conditions.
DSS structure and algorithmic transparency in APL
Authors: Cundiff W. E.
Published: January 2007

Earlier discussion focused on APL as an executable notation for understanding the inner-workings of dialogue generation and data/model base management in Decision Support Systems (DSS). The present work applies the notion of algorithmic transparency to the broader properties of system structure that connect the technology components of DSS. Using a concise set of idioms, embodying only the control construct of sequence, APL's direct definition form is employed in revealing patterns in the specification of a functional prototype Group DSS (GDSS).
How to manage large APL projects
Authors: Eller Richard R. N.
Published: January 2007

There is a common trend towards Graphical User Interfaces (GUI). Writing applications for such an environment puts new demands on designing software and managing its development. The applications software needs to be event based. It needs to have a special uniform "feel" and provide flexibility for both the novice and experienced user.Many of the new GUI oriented needs can be handled by traditional User Interface Toolkits or Libraries. However, using these will not solve the complexity of a good user interface design. Another approach is to choose or design a User Interface Management System (UIMS). UIMS is responsible for all user interface action and only when necessary will call actual application code for performing e.g. a calculation or data base operation.The paper describes the architecture of a large real-life UIMS based APL application project. Since a UIMS approach differs from traditional hierarchical programming, many of these differences are described in detail. Particular emphasis has been put on how this approach has affected project management and the various tasks of a software project. The paper ends by presenting some thoughts about future APL Application Development Systems.
CATS
Authors: Jordan Maurice
Published: January 2007

This paper describes the implementation of an automated test system for APL functions. It extends an implementation of assertive comments in APL to derive a notation for formal specification using pre and post conditions. These conditions are APL statements and so can be built into test functions. Data supplied to provide examples is captured and subjected to mutations to test behaviour under edge conditions. The techniques make extensive use of modern APL ideas such as defined operators, phrasal forms and function assignment.
A0 system
Authors: Miroshnikov Alexei I.
Published: January 2007

This paper describes an automation system for construction planning, named A0. A0 was developed for usage by big building companies at various stages of preparing and executing construction works. It supports different tasks starting with calculation of project estimates, bills of materials, and schedules of works and ending by providing the company executives with complete information for the supervision of the building process in their company. A0 includes also a DBMS for the All Union Data Base on Construction. The amount of data in the data base is about 45MB for the Leningrad region only. At present the system is used by the Leningrad Building Corporation.A0 is all written in APL★PLUS/PC. The system will be distributed with the run-time system of APL★PLUS for the Soviet customers just after the performance test. The A0 system was developed in market competition with six similar projects using different programming systems: FoxBase, Clipper, Turbo-Pascal, and the MS C-compiler. The advantages of the system under consideration were, in many ways, ensured by choosing APL. Some advantages and disadvantages of using APL for that kind of application system are discussed in the paper as well.
Supply-chain management at Rowntree
Authors: Smith Adrian
Published: January 2007

APL has been in use at Rowntree Mackintosh since late 1978; during this time it has developed from an initial application to "little local systems" to play a vital role in the supply-chain management of the company. APL systems are now deeply embedded in all stages of company operations, from recipe modelling to the scheduling of raw materials, from five-year planning to detailed shift-by-shift production scheduling.This paper sets out to explain the critical success factors which encouraged the directors of Rowntree Mackintosh to entrust such a vital part of their business operations to an obscure Greek language which executes backwards.
A control theory perspective on configuration management and Cfengine
Authors: Burgess Mark
Published: January 2007

Cfengine is an autonomous agent for the configuration of Unix-like operating systems. It works by implementing a hybrid feedback loop, with both disrcete and continuous elements.
Financial and operational aspects of a multivendor installation in a nonmetropolitan area
Authors: Cartlidge D. R. , Mann J. M.
Published: January 2007

The New Mexico State University Computer Center has recently installed a multivendor configuration of major system components. Although some special problems were anticipated because the University is not located in close proximity to metropolitan areas, the configuration has been profitable in terms of both economy and increased performance.The primary hardware, an IBM 360/65 computer, a quarter of a million bytes of core and channels were purchased from a non-IBM source, while other IBM components were leased or purchased from IBM. A third vendor supplied two million bytes of extended core storage, twelve disk and two tape drives. A major administrative teleprocessing service utilizes CRT terminals provided by a fourth vendor.The paper discusses the financial advantages of moving to a multivendor installation and explores maintenance problems arising from such an operation. Primary emphasis is given to unique problems which result from being in a location remote from vendor installations, and recommendations are made to others contemplating a multivendor installation.
The Wikipedia XML corpus
Authors: Denoyer Ludovic , Gallinari Patrick
Published: January 2007

Wikipedia is a well known free content, multilingual encyclopedia written collaboratively by contributors around the world. Anybody can edit an article using a wiki markup language that offers a simplified alternative to HTML. This encyclopedia is composed of millions of articles in different languages.
Incorporating context within the language modeling approach for
ad hoc
information retrieval
Authors: Azzopardi Leif
Published: January 2007

Using context to improve retrieval performance is a current challenge within the discipline and presents a major challenge to the research community. In this thesis, the context of documents formed via semantic associations is utilized within the Language Modeling (LM) approach for
ad hoc
Information Retrieval.
Text mining for product attribute extraction
Authors: Ghani Rayid , Probst Katharina , Liu Yan , Krema Marko , Fano Andrew
Published: January 2007

We describe our work on extracting attribute and value pairs from textual product descriptions. The goal is to augment databases of products by representing each product as a set of attribute-value pairs. Such a representation is beneficial for tasks where treating the product as a set of attribute-value pairs is more useful than as an atomic entity. Examples of such applications include demand forecasting, assortment optimization, product recommendations, and assortment comparison across retailers and manufacturers. We deal with both implicit and explicit attributes and formulate both kinds of extractions as classification problems. Using single-view and multi-view semi-supervised learning algorithms, we are able to exploit large amounts of unlabeled data present in this domain while reducing the need for initial labeled data that is expensive to obtain. We present promising results on apparel and sporting goods products and show that our system can accurately extract attribute-value pairs from product descriptions. We describe a variety of application that are built on top of the results obtained by the attribute extraction system.
The problem of disguised missing data
Authors: Pearson Ronald K.
Published: January 2007

Missing data is a well-recognized problem in large datasets, widely discussed in the statistics and data analysis literature. Many programming environments provide explicit codes for missing data, but these are not standardized and are not always used. This lack of standardization is one of the leading causes of the subtle problem of
disguised missing data
, in which unknown, inapplicable, or otherwise nonspecified responses are encoded as valid data values. Following a brief overview of the problem of explicitly coded missing data, this paper discusses sources, consequences, and detection of disguised missing data, including two real-world examples. As the first of these examples illustrates, the consequences of disguised missing data can be quite serious. The key to its detection lies in first, recognizing disguised missing data as a possibility and second, finding a sufficiently informative view of the data to reveal its presence.
Engineering management considerations in data center security
Authors: Wilk Robert J.
Published: January 2007

This paper presents an overview of some of the technical and managerial aspects of protecting the personnel, data processing systems and computer facility from deliberate or accidental damage by internal or external forces.With regard to site planning, the environmental compatibility between the computer system, its data communication and electric energy systems must be established. Electro-magnetic spectrum area profiles are utilized to detect high energy transmitters which could necessitate shielding of the facility and filtering of all incoming wire lines. The effects of magnetic fields on magnetic storage media is also discussed.The unique requirements of real-time, on-line systems, i.e. airline reservation, satellite tracking, require special solutions related to uniterruptable power systems (UPS). In this context this paper will also examine the management decisions which must be made regarding the cost effectiveness of a "fail safe" vs "fail soft" system.Data security is examined in light of the time-value relationship of information applied to programming changes, data transmission to remote terminals, available software and hardward cryptography systems.The application of various electro mechanical devices and computing systems for use in area control situations is examined. Additionally, the relatively new use of voice, hand and fingerprints for access control is surveyed.The use of closed circuit television and its effect on personnel management will also be considered. Low light level techniques and time-lapse video tape recording sub systems applied to unmanned surveillance of critical areas or processes is discussed.
The programmer selection interview
Authors: Scott Randall F.
Published: January 2007

Many organizations have very elaborate techniques for selecting new employees. Most of these are screening processes to select applicants who will eventually be given the opportunity of an interview with a program project manager or supervisor. This interview is frequently the final determining factor in the selection process of a new computer programmer. Unless the interview is conducted in a manner that is both fair and revealing, a course of action will be begun that will be difficult to change at a later time. With the cost of personnel now being the most expensive item in program development projects, this personnel selection decision is now more critical than ever before.
Symbolic computation of Fenchel conjugates
Authors: Bauschke Heinz H. , Mohrenschildt Martin v.
Published: January 2007

Convex optimization deals with certain classes of mathematical optimization problems including least-squares and linear programming problems. This area has recently been the focus of considerable study and interest due to the facts that convex optimization problems can be solved efficiently by interior-point methods and that convex optimization problems are actually much more prevalent in practice that previously thought.Key notions in convex optimization are the Fenchel conjugate and the subdifferential of a convex function. In this paper, we build a new bridge between convex optimization and symbolic mathematics by describing the Maple package fenchel, which allows for the symbolic computation of these objects for numerous convex functions defined on the real line. We are able to symbolically reproduce computations for finding Fenchel conjugates and subdifferentials for numerous nontrivial examples found in the literature.
Listener training for speech-output applications
Authors: Rosson Mary Beth
Published: January 2007

The specificity of the adaptation to synthetic speech known to occur with practice was examined by giving listeners selective exposure to a subset of English phonemes (a control group was “trained” on analogous materials produced by a human speaker), and then testing their ability to identify words created from both the previously heard and novel phonemes. The results indicated that while synthetic voice training was generally facilitative, it was most helpful in the identification of the sounds heard before. However, this specific learning effect occured for only certain phonemes. The findings imply that one way to maximize early adaptation to synthetic speech is to identify the “learnable” sounds, and to increase users' exposure to them during introductory or training dialogs.
A theory of stimulus-response compatibility applied to human-computer interaction
Authors: John Bonnie E. , Rosenbloom Paul S. , Newell Allen
Published: January 2007

A GOMS theory of stimulus-response compatibility is presented and applied to remembering computer command abbreviations. Two abbreviation techniques, vowel-deletion and special-character-plus-first-letter, are compared in an encoding task. Significant differences are found in the time to type the first letter of the abbreviation, and in the time to complete the typing of the abbreviation. These differences are analyzed using the theory which produces an excellent quantitative fit to the data (r
2
= 0.97).
An evaluation of an eye tracker as a device for computer input2
Authors: Ware Colin , Mikaelian Harutune H.
Published: January 2007

Since humans direct their visual attention by means of eye movements, a device which monitors eye movements should be a natural “pick” device for selecting objects visually present on a monitor. The results from an experimental investigation of an eye tracker as a computer input device are presented. Three different methods were used to select the object looked at; these were a button press, prolonged fixation or “dwell” and an on screen select button. The results show that an eye tracker can be used as a fast selection device providing that the target size is not too small. If the targets are small speed declines and errors increase rapidly.
Modular implementation of presentations
Authors: Szekely Pedro
Published: January 2007

The presentation of an application program specifies how the data and operations provided by an application are presented to users. Most traditional techniques for implementing presentations lead to unstructured, unmodular implementations that are hard to construct and change. We present a model of presentation that identifies the dependencies between the presentation and functionality portions of an application. Based on this model, we show how several implementation techniques can be used to construct presentations in a modular way.
Evaluating user and system models
Authors: Kellogg Wendy A. , Breen Timothy J.
Published: January 2007

A user's mental model of a system should be an important determinant of performance and as well as a means of understanding why particular user errors occur. In particular, experienced users' models should be in closer agreement with the system than less experienced users' models, and deviations of expert models from the system should correspond to difficulties in performance and suggest ways that system usability could be improved. The present study explored the utility of scaling techniques for defining and comparing user and system models. The results support the assertion that with experience users' mental models approach the system model. However, even experienced users had significant deviations from the system model, leading to predictions of where experts would have difficulty using the system and suggestions for improving usability.
Social and psychological factors influencing the design of office communications systems
Authors: Ehrlich Susan F.
Published: January 2007

Office automation is used by groups of people with complex communication needs to help them reach business goals such as scheduling, tracking, reviewing, and delegating. Effective individual and group decisions are heavily dependent on communication protocols and social conventions. Because these conventions are so ingrained, they are sometimes not readily available to conscious inspection during the design of communication systems. Even more problematic, system designers may not have first hand knowledge of the conventions and protocol for the range of environments in which their systems will be used. Nevertheless, office systems must work in tandem with these conventions. Wang Laboratories has a continuing program of research directed at identifying the psychological and social factors that come into play during the adoption and use of computer communication systems and the implications of these factors for the design of those systems. Highlights of a three year program of research are presented covering implications for voice mail, electronic mail, and electronic calendars.
Designing optimum CRT text blinking video image presentation
Authors: Kitakaze Seiji , Kasahara Yutaka
Published: January 2007

A reference scale has been established to assist in the determination of optimum text blinking times for portions of video image texts being presented on CRT display systems. Optimum text blinking time herein is considered to be that time which most effectively catches and holds viewer attention and quickens his understanding of message import. Three experiments involving questions of the psychology of blinking time were conducted. The first experiment examined subjects' preconceived notions of optimum blinking time, i.e. what they imagined, within their own minds, such times would be for specific text portions. The second experiment determined the gap between those preconceived notions and the subjects' changed concepts of optimum blinking times, based on their experience of visual trials. The third experiment applied a scale of blinking times, based on the experience gained in the second experiment, to a new set of subjects in order to further refine our understanding of optimum intervals. For the portions of text used here, optimum blinking times centered about 1.0 second.

Moreover, through an adaptation to the video image presentation system, the effectiveness of the optimum text blinking times and the psychological scale was confirmed.
A case example of human factors in product definition: needs finding for a voice output workstation for the blind
Authors: Kane Richard M. , Yuschik Matthew
Published: January 2007

Human factors efforts can contribute to product design at every design phase from conception through evaluation of a product in the field. Early human factors involvement has certain advantages. The major advantage is that it can have greater “leverage” by influencing more far-reaching aspects of a product. Input at later design phases, on the other hand, may delay product schedules or require a major re-design effort. Input at earlier stages can diminish these problems. As a case example, a needs finding study for a voice output workstation for the blind is described. Users of these workstations participated in a semi-structured interview to determine their needs. Results identified specific features needed. The findings also indicated that the original scope of the project, word processing, should be broadened to include other applications.
Towards universality of access: interfacing physically disabled students to the Icon educational microcomputer
Authors: Verburg Gerbrand , Field Debbie , St. Pierre Francois , Naumann Stephen
Published: January 2007

A micro-processor based Interface Unit and Teacher Utility have been developed at the Hugh MacMillan Medical Centre that will facilitate physically disabled users' access to the Icon educational microcomputer. The Interface Unit allows a variety of alternate input devices to be used with the Icon computer. Evaluations of the use of the Icon by physically disabled students without and with the Interface Unit were completed. The Teacher Utility offers on-line instruction and support for teachers with physically disabled students who have problems accessing the Icon. The design of the Teacher Utility is presented from three perspectives: the teacher, the physically disabled student, and the developers.
A self-regulating adaptive system
Authors: Trevellyan Robert , Browne Dermot P.
Published: January 2007

The viability of providing adaptive user interfaces has been demonstrated ([3], [5]). Such systems identify differences between users in order to provide purposeful change at the user interface. Thus, adaptive systems have objectives, as indicated by the term 'purposeful.' The research reported here takes an important step forward by demonstrating that adaptive systems can be built that regulate their own behaviour by assessing whether their adaptations are being successful in meeting these objectives.
Positioning human factors in the user interface development chain
Authors: Grudin Jonathan , Ehrlich Susan F. , Shriner Rick
Published: January 2007

Human factors professionals are not completely free to support the optimization of user interface design within the time span of individual software development projects. Interface design is constrained by conservative forces, such as the expectations of users of existing systems in the installed base and emerging de facto or formal standards. At the same time, human factors involvement with a particular product may ultimately have its greatest impact on future product releases. In this paper we explore an expanded time line for influencing product design. This time line brings middle- and upper-management concerns into focus, revealing critical opportunities for effectively positioning and applying human factors resources.