On the almost-sure sample stability of systems with randomly time-varying delays

In a large class of multi-loop control systems, many feedback loops are “closed” through a time-shared digital computer, by means of algorithms which require information from sources which are sampled at a rate which is not synchronized with the sampling of the individual “plants”. This mis-synchronization, coupled with variations in the computer's task load caused by “interrupts”, results in a randomly time-varying delay in the closing of the various feedback loops. Consequently, the dynamics of each controlled “plant” in such a system may be modeled by means of a stochastic delay-differential equation. This paper presents some new research results concerning the sample stability, as opposed to statistical, or ensemble stability, of linear stochastic delay-differential equations.     

Interactive applications of personal situation-aware assistants

Ultraportable mobile computers provide electronic assistance for environments and usage situations, where computer support up to now has not been feasible. For the first time, a true physical and cognitive integration of computer support into the everyday business of the real-world becomes possible, as envisioned in Mark Weiser's concept of “ubiquitous computing” (Weiser, Communication of the ICM 1993, 36 (12): 75–85). However, although Handheld-PC, etc. today; already support a good deal of personal information management and basic access to distributed multimedia information services such as the World-Wide Web, they are still surprisingly difficult to use in “full action”. Specifically, lengthy interaction sequences and the inability to find quickly that important piece of information which is embedded somewhere in the machine, makes using those devices sometimes a very disappointing experience. In this, paper, we outline a new approach to realizing an easy-to-use personal digital assistant systems, based on the concept of Situation Awareness. Using knowledge about task structures, situation dependencies, and task contexts, our concept allows a mobile assistant to proactively provide the right information at the right time and the right place, without intruding upon the users primary task: interacting with reality.     

“Paraprogramming” manufacturing information systems

Computer integrated manufacturing (CIM) is creating unexpected problems for a growing number of manufacturing companies. Manufacturers are finding it especially difficult to attract programmers who are both willing and able to develop the highly complex software that integrates existing accounting, sales, production, engineering, and quality control information subsystems. Consequently, many companies abdicate their responsibility for manufacturing information systems and seek third party support ranging from consulting assistance to a total takeover of the company's information resources and operations. Companies that “give away” their internal information system capabilities to third parties will ultimately lose control of their enterprise information, a danger to be avoided. Off-the-shelf software for desktop computers has become sufficiently powerful to help solve a major portion of this serious problem. We hypothesize that manufacturing engineers (and others) can be trained to use packaged software to leverage their company's systems programming capabilities. In effect they would become “paraprogrammers” who would help design, develop, and maintain manufacturing information systems. This new type of professional would not require a computer science or similar educational background, but could be trained to satisfy many specialized programming needs in a manner similar to how paramedics and paralegals are trained and used in the medical and legal professions, respectively. This paper reports on the early stages of research to determine whether or not product design engineers can use a desktop relational database management system and its various command languages to develop a master bill of material information system (BOMIS). The purpose of the research is to evaluate the amount of programming complexity reduction and increased operational effectiveness that can be achieved through paraprogramming by manufacturing engineers.     

Flexible Bytecode for Linking in .NET

Dynamic linking in modern execution environments like .NET is considerably more sophisticated than in the days of C shared libraries on UNIX. One aspect of this sophistication is that .NET assemblies embed type information about dynamically linked resources.This type information implicitly represents compile-time assumptions about the resources available at run-time. However, the resources available at run-time may differ from those available at compile-time. For example, the execution environment on a mobile phone might provide fewer, simpler classes than on a desktop PC. As bytecode cannot adapt to its execution environment, component reuse is restricted and development costs are increased.We have designed and implemented a “flexible” dynamic linking scheme that binds bytecode as late as possible to the assemblies and classes available in a .NET execution environment. We describe the scheme's integration with the .NET linking infrastructure, review important design decisions and report on experiences with the “Rotor” shared source version of .NET.     

A clustering method to distribute a database on a grid

Clusters and grids of workstations provide available resources for data mining processes. To exploit these resources, new distributed algorithms are necessary, particularly concerning the way to distribute data and to use this partition. We present a clustering algorithm dubbed Progressive Clustering that provides an “intelligent” distribution of data on grids. The usefulness of this algorithm is shown for several distributed datamining tasks.     

Integration of neural networks and genetic algorithms for an intelligent manufacturing controller

This paper addresses the development and implementation of a “controller” for a single manufacturing machine. This prototype will serve as an important tool to study the integration of several functions and the utilization of status data to evaluate scheduling and control decision alternatives. The emphasis is on creating a prediction capability to aid in assessing the long-term system performance impact resulting from decisions made and environmental changes. This prediction capability is implemented by using neural networks, simulation, and genetic algorithms. Neural networks predict the behavior of different sequencing policies available in the system. The contribution of the genetic algorithms to the decision-making process is the development of a “new” scheduling rule based on a “building blocks” procedure initiated by the neural networks     

Applying abstraction and formal specification in numerical software design

Numerical software development tends to struggle with an increasing complexity. This is, on the one hand, due to the integration of numerical models, and on the other hand, due to change of hardware. Parallel computers seem to fulfill the need for more and more computer resources, but they are more complex to program.

The article shows how abstraction is used to combat complexity. It motivates that separating a specification, “what,” its realisation, “how,” and its implementation, “when, where,” is of vital importance in software development. The main point is that development steps and levels of abstraction are identified, such that the obtained software has a clear and natural structure.

Development steps can be cast into a formal, i.e., mathematical framework, which leads to rigourous software development. This way of development leads to accurate and unambiguous recording of development steps, which simplifies maintenance, extension and porting of software. Portability is especially important in the field of parallel computing where no universal parallel computer model exists.     

Computer aided drafting with refresh graphics

Practically all the “turn-key” CAD/CAM systems now marketed use a storage tube for the interactive graphics display. The major disadvantages of the storage tube are that the draftsman cannot immediately see the effect of any erasing routines that he has used and he may have a wait of many seconds for a complete redraw of his work. The paper describes a system which was developed for the benefit of undergraduate and postgraduate courses as no “turn-key” system is accessible for demonstration purposes. It is mounted on a desk-top computer with refresh graphics which have been fully exploited as an aid to rapid drafting.     

Constructive logics Part I: A tutorial on proof systems and typed λ-calculi

The purpose of this paper is to give an exposition of material dealing with constructive logics, typed λ-calculi, and linear logic. The emergence in the past ten years of a coherent field of research often named “logic and computation” has had two major (and related) effects: firstly, it has rocked vigorously the world of mathematical logic; secondly, it has created a new computer science discipline, which spans a range of subjects from what is traditionally called the theory of computation, to programming language design. Remarkably, this new body of work relies heavily on some “old” concepts found in mathematical logic, like natural deduction, sequent calculus, and λ-calculus (but often viewed in a different light), and also on some newer concepts. Thus, it may be quite a challenge to become initiated to this new body of work (but the situation is improving, and there are now some excellent texts on this subject matter). This paper attempts to provide a coherent and hopefully “gentle” initiation to this new body of work. We have attempted to cover the basic material on natural deduction, sequent calculus, and typed λ-calculus, but also to provide an introduction to Girard's linear logic, one of the most exciting developments in logic these past six years. The first part of these notes gives an exposition of the background material (with some exceptions, such as “contraction-free” systems for intuitionistic propositional logic and the Girard translation of classical logic into intuitionistic logic, which is new). The second part is devoted to more current topics such as linear logic, proof nets, the geometry of interaction, and unified systems of logic (LU).     

Group technology applications in manufacturing operations through the computer system

The typical manufacturing facility is constantly developing new product designs and related manufacturing processes. The increased volume of new designs and processes causes rapid and inefficient construction of product designs and manufacturing processes. Many parts and manufacturing processes are developed over the life cycle of a production facility with no organized means of cataloging this past and present data. This procedure is extremely ineffective because there is no way to determine if a part or process has been previously developed. The constant “reinventing of the wheel” creates a tremendous waste of manpower and cost.

One approach to solving this problem is through the use of group technoogy. Group technology is the identification and grouping of similar parts and processes in order to take avantage of their similarities in the design and manufacturing process. Parts and processes can be grouped under a classification and implemented with a coding system. Concurrently, the number of parts and processes can be reduced by putting them in a “family.” This “family” has common characteristics such as shape, size, color, tolerance or production operations.

For handling and manipulation of this data, a computer system has been developed. The computer system would set up a reporting format that would classify, code and group the parts and processes, so the user can analyze if a previously designed process or part can be used in the current system and/or if a better layout can be feasible.

Many advantages such as reduced inventory cost, increased facility space and better utilization of manpower are but a few of the benefits from this system.     

Algorithms for parallel processing: curve and surface definition with Q-splines

The emergence of parallel array processing, both in software methodology and hardware technology, opens new avenues for the implementation and optimization of systems for interactive computer graphics. The Q-spline interpolation method is presented, designed for incremental curve definition, local curve modification, “on-the-curve” control points and computational efficiency in array processing environment. The implementation and performance of the algorithms in the environment of a general purpose interactive computer graphics system is described.     

Personalization of internet telephony services for presence with SIP and extended CPL

This paper discusses issues of personalization of presence services in the context of Internet Telephony. Such services take into consideration the willingness and ability of a user to communicate in a network, as well as possibly other factors such as time, address, etc. Via a three-layer service architecture for communications in the session initiation protocol (SIP) standard, presence system basic services and personalized services (personal policies) are clearly separated and discussed. To enrich presence related services, presence information is illustratively extended from the well known “online” and “offline” indicators to a much broader meaning that includes “location”, “lineStatus”, “role”, “availability”, etc. Based on this, the call processing language (CPL) is extended in order to describe presence related personalized services for both call processing systems and presence systems using information such as a person’s presence status, time, address, language, or any of their combinations. A web-based system is designed and implemented to simulate these advanced services. In the implementation, personal policies are programmed by end users via a graphic user interface (GUI) and are automatically translated into extended CPL. The simulation system clearly displays when, where and what CPL policies should be used for the provision of personalized presence services and call processing services. Policy conflicts are also addressed by setting policy priorities in the system.     

Towards agent systems engineering

The term “ ” has became a buzzword these days, not only in academic circles, but also in some computer magazines and application fields of computer science like manufacturing and logistics. Hence, there is a pressing need for a design methodology for multi-agent systems. Or even stronger, there is a demand for an agent engineering technology, which includes computer assistance during the design phases, for the validation of the designed system, and for the implementation of the multi-agent system as a physically distributed system. This status report will introduce the field of multi-agent systems and its design. Three prominent applications will serve as a first motivation of the theme. Based on the ideas of the agent examples a discussion on the term agent will serve as a first motivation of the theme. Based of the theme. Based on the ideas of the agent architecture of an agent, its communication capabilities, and planning in a multi-agent context. After this broad technical introduction the main topic of this work will be tackled. An introduction to five methodologies for the design of multi-agent systems will be given and a new one, the method, will be presented. Eventually a brief discussion about the multi-agent design approaches will be given, the missing correlations to the task definitions will be critizised, and further research directions will be proposed.     

Linking microcomputers and dedicated word processing systems for increased productivity

With the decline in cost of hardware, more and more professionals are acquiring personal computers at their desk. Most common uses of these office computers are word processing and spreadsheet (e.g. LOTUS 123, MULTIMATE, FRAMEWORK, etc.¹) applications. Professionals typically generate text directly on the personal computer (in lieu of hand written copy) and use spreadsheet programs to tabulate and analyze collected field data. A problem in some offices is integrating text and data prepared on the personal computer with existing dedicated word processing systems which have existed in many office environments for some time. One solution is to have the text and tabulated data retyped into the word processing system, however, this approach is not an effective use of resources.

The Industrial Hygiene Section, Industrywide Studies Branch (DSHEFS), NIOSH has developed procedures for electronically linking personal microcomputers with an office-wide word processing system. Using a commercially available hardware “board” (which may be inserted into an open slot in an IBM-PC or compatible), the rough copy report and tabulated spreadsheet data can be electronically linked and “uploaded” from a microcomputer to the word processing system. At NIOSH, a WANG word processing system is the office-wide system for preparing and publishing final reports. This system is not readily compatible with IBM-PC (or similar) microcomputers; however, using MULTIMATE (a commercially available word processing program) and the hardware board, documents can be readily transferred to the WANG virtually unchanged from the copy generated on the microcomputer. Importantly, spreadsheet data can be similarly transferred and linked to a document on the WANG wordprocessing system.

This paper describes the sequence of steps, along with necessary hardware and software, to achieve the integration of written documents and numerical data (analyzed by LOTUS 123) from a microcomputer to a office-wide WANG word processing system.     

A simulation of U.S. Navy training pipelines

The system by which the U.S. Navy trains personnel is modeled using the SLAM computer language. By incorporating both network simulation techniques and discrete event logic, the flow of students from a Recruit Training Center (RTC) through the Basic Electricity and Electronics (BEE) schools, the “A” schools and eventually to the fleet, is modeled to a level of detail represented by an individual BEE/“A” school classroom. Inputs for the model include the daily influx of trainees into an RTC for each classification, as well as the various drop, attrition and setback rates.

Since the objective of the study was to allow Navy representation to identify potential bottlenecks prior to their occurrence, the output variables depict both resources utilization and queuing statistics. The simulation model was executed, and the resulting outputs were used to test hypotheses.     

The etiology of computerphobia

Computerphobics, Uncomfortable Computer Users, and Control Group subjects were interviewed on their retrospective computer and mechanical experiences, personality style, and media influence on the development of computer feelings. Results indicated that psychological reactions to early mechanical and computer experiences differed between the three groups with etiological roots of computerphobia evident as early as childhood. Gender and attitude of the technology “introducer” were important in predicting later psychological reactions to computers. Computerphobics appeared to suffer from a more generalized “technophobia” while Uncomfortable Computer Users were apprehensive only about computers. Personality styles differed only slightly between the three groups with Computerphobics being less persistent in problem solving and less likely to seek assistance. Prevention and intervention implications include: effective nonevaluative introduction of technology in the school system by “introducers” who are comfortable and skilled with computer technology; and identification and treatment of current Computerphobics.     

Color enhancement of highly correlated images. I. Decorrelation and HSI contrast stretches

Conventional enhancements for the color display of multispectral images are based on independent contrast modifications or “stretches” of three input images. This approach is not effective if the image channels are highly correlated or if the image histograms are strongly bimodal or more complex. Any of several procedures that tend to “stretch” color saturation while leaving hue unchanged may better utilize the full range of colors for the display of image information. Two conceptually different enhancements are discussed: the “decorrelation stretch”, based on principal-component (PC) analysis, and the “stretch” of “hue”-“saturation”-intensity (HSI) transformed data. The PC transformation is scene-dependent, but the HSI transformation is invariant. Examples of images enhanced by conventional linear stretches, decorrelation stretch, and by stretches of HSI transformed data are compared. Schematic variation diagrams or two- and three-dimensional histograms are used to illustrate the “decorrelation stretch” method and the effect of the different enhancements.     

Constrained multibody system dynamics an automated approach

The governing equations for constrained multibody systems are formulated in a manner suitable for their automated, numerical development and solution. Specifically, the “closed loop” problem of multibody chain systems is addressed.

The governing equations are developed by modifying dynamical equations obtained from Lagrange's form of d'Alembert's principle. This modification, which is based upon a solution of the constraint equations obtained through a “zero eigenvalues theorem,” is, in effect, a contraction of the dynamical equations.

It is observed that, for a system with n generalized coordinates and m constraint equations, the coefficients in the constraint equations may be viewed as “constraint vectors” in n-dimensional space. Then, in this setting the system itself is free to move in the n−m directions which are “orthogonal” to the constraint vectors.