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Many manufacturing processes require time-consuming setups before automation can begin. This paper investigates the applications of distributed-parameter computational thermal-fluid models for automating the design of a continuous manufacturing system, which aims at reducing process setup time. A generic draw process is used as an example throughout this paper, which involves practically all modes of heat transfer. Two physically accurate distributed-parameter models (semi-two-dimensional (2-D) and quaisi-one-dimensional (1-D) are derived and experimentally validated. In deriving these models, we relax a number of assumptions commonly made in modeling draw processes, and extend the models to allow for 2-D static/dynamic response predictions. The semi-2-D model provides a means to accurately predict the free surface geometry and the location at which the glass solidifies into a fiber, which also serves as a basis to derive the quais-1-D model. The quasi-1-D model that explicitly solves for the controlled variables is attractive for control system design and implementation. These results are particularly important in the optical-fiber industry because the difficulties in making precise in situ measurements in the harsh environment of the draw process have posed a significant challenge in the control of fiber diameter uniformity. Additionally, these numerically computed and experimentally measured neck-down profiles obtained in an industry setting can be used as benchmark data for future comparisons. The modeling approaches presented here are applicable to a variety of thermal-fluid systems, such as thermal processing of semiconductor wafer and food. Despite the emphasis in this paper on the faster draw of large-diameter glass that is a padicipating media in radiation, the technique for predicting the 2-D temperature distribution and the streamlines describing the fluid flow is equally applicable to processes involving nonparticipating media, such as composite, polymer, or synthetic fibers. Note to Practitioners—This paper is motivated by a problem in the fiber draw industry because of the progressive difficultly in maintaining the diameter uniformity resulting from the ever-increasing preform (or glass rod) diameter and draw speed. The larger diameter a preform is, the longer the fiber can be drawn in the furnace from a single preform and in much less time by drawing at a higher speed. The number of setups to initiate the draw can thus be drastically lowered. The tradeoff, however, is that the glass takes a longer distance to cool into a fiber after leaving the furnace, for which an insulated post-chamber is added to gradually cool the fiber to solidification in order to reduce optical losses in the final product. Existing models assuming a Dirichiet boundary condition at the furnace exit are valid only for drawing a small-diameter preform as long as the fiber solidifies inside the furnace. As larger preforms are drawn at higher speeds, it is necessary to locate the solidification for optimizing the post-chamber design, and to develop high-fidelity models for controlling the diameter uniformity. This paper formulates a general 2-D thermal-fluid dynamic model (which does not rely on assumptions commonly made for small preforms) to characterize the free-surface flow of the glass in both the furnace and the post-chamber. We demonstrated how a detailed description of the free surface geometry, temperature fields, and streamlines can be accurately computed from the 2-D model for process design, which also provides a basis to derive a distributed quasi-1-D model explicitly solving for the essential process state variables. Both models have been experimentally validated (with a 9-cm-diameter glass preform) by comparing against the data obtained (at 25 m/s) in an industry setting. These models have been successfully applied to the design of commercial draw towers. [ABSTRACT FROM AUTHOR]

In our earlier work, we introduced a state-based approach for the diagnosis of repeatedly occurring failures in discrete event systems (DESs). Since temporal logic provides a simpler way of specifying system properties; in this paper, a temporal- logic-based approach for diagnosing the occurrence of a repeated number of failures is developed. Linear-time temporal-logic (LTL) formulae are used to represent the specifications of DESs. Notions of prediagnosability for failures and diagnosability for repeated failures are introduced in the setting of temporal logic. A poly-nomial algorithm for the test of prediagnosability for failures is provided. The diagnosis problem for repeated failures in the temporal-Logic setting is reduced to one in a state-based setting, and so the prior results of a state-based repeated failure diagnosis can be applied. Finally, a simple example is given for illustration. Note to Practitioners—Certain failures in a system are repeats able, such as routing errors in a manufacturing system. A theory for the diagnosis of such failures was presented in an earlier work of Jiang et at The present paper uses temporal logic to specify such failures. It turns out that repeatable failures can be specified as violations of invariant properties (i.e., properties that must always hold). Given an invariant property that the system must always satisfy, an algorithm is presented to refine the system model and label those states of the refined system where the property is violated. The problem of repeated diagnosis then requires deter- mining, within a bounded delay, each time a "failure-state" is visited. For this analysis, the existing theory developed by Jiang et at is used. [ABSTRACT FROM AUTHOR]

Dual-head placement machines, which operate according to a highly complex logic, are commonly used in circuit-card assembly lines to place large components with a high degree of accuracy. The purpose of this paper is to present a unique approach for optimizing the picking operations of a dual-head placement machine with the ultimate goal of improving the efficiency of assembly operations. Research objectives are a model that reflects relevant, practical considerations; a solution method that can optimize problems effectively (i.e., within accept- able run times); and tests to establish computational benchmarks. We formulate a general integer, set covering model, and optimize it using column generation, generating columns by solving a specially designed, constrained shortest-path subproblems. Test results demonstrate the efficacy of our optimizing approach on problems of realistic size and scope. Note to Practitioners—The dual-head placement machine (DHPM) motivated this research because it is widely used in the circuit-card assembly industry and is an extremely intricate machine that operates according to a highly complex logic. No earlier study provided a method to optimize DHPM picking operations. This paper presents a novel solution methodology that formulates a unique model of picking operations and adapts ways to solve it progressively to optimize picking operations. The solution improves the efficiency and productivity of a DHPM by prescribing a process plan that minimizes the total time required to pick all components that are then placed on a circuit card. This paper relates key insights that allow the problem to be structured for solution, including certain rules that govern DHPM picking operations and ways in which components can be picked. Key contributions include methods to construct graphical representations of the complex logic of picking operations (e.g., representing nozzle changes and five types of picks, including gang picking), specialized solution algorithms, and computational benchmarks that illustrate the capabilities of the solution approach. The approach does not appear to be limited in representing picking operations but must be combined with other methods to prescribe a complete process plan, including assigning component types to feeder slots, placing operations, and sequencing pick/place operations. This work can be extended by adapting the column generation approach to prescribe optimal DHPM placing operations and to prescribe process plans for other types of placement machines. [ABSTRACT FROM AUTHOR]

In this paper, a generic model for the synthesis of tolerances for manufactured parts is presented. The model uses a method of transforming traditional tolerance specifications (as defined in ASME Y14.5M) to a generalized coordinate system (hereinafter referred to as deviation space). Small displacement torsors (SDTs) have been used for representing the deviations. The tolerance synthesis method is formulated as a constrained nonlinear optimization process. Three different types of constraints have been considered for the optimization process: 1) representation of assemblability; 2) mapping of tolerance specification to deviations; and 3) functional requirements. A new deviation-based cost of manufacturing model has been proposed. A working module of the scheme has been implemented and the process has been elaborated with two examples. The possibility of extension of the model and scope for further generalization have been discussed. Note to Practitioners-This paper presents an optimization method for finding tolerance values for different features of an assembly of manufactured parts. Determination of different types of tolerances and their exact values for critical features of any part has been an ad-hoc process; it has been mostly experience-based till recent time. In this paper, efforts have been made to establish a strong mathematically oriented method for synthesis of tolerances. The procedure attempts to minimize cost of manufacturing while the functionality and assemblability are satisfied. It is a generalized method and could be applied for designing rigid manufacture parts. For practical usage, this method should be integrated with three-dimensional computer-aided design packages as a tolerance synthesis module for integrated tolerance design. [ABSTRACT FROM AUTHOR]

This paper builds on our August 2004 paper where data fusion is used to combine results from multiple audio and video localizers in order to locate a talker in video conferencing applications. The two studies differ in the type of data fusion engine used. The former study explored using a summing voter for data fusion, whereas this study employs a Bayesian network. The novelty of both papers is the use of reliability estimates to improve the overall localization performance and robustness. Reliability estimates, which are derived based on known physical properties of each individual localizer, were used to gauge the trustworthiness of the current localization results. These reliability estimates were introduced into the fusion engines to achieve better performance. Although the summing voter fusion engine used in [1] improves the overall localization performance, it does not take into account the unique characteristics of each localizer. The Bayesian network allows the inclusion of these unique characteristics as part of the fusion process and therefore further improves the overall localization performance. When one or more localizers fails, the persistent erroneous data streams from the failed localizers can negatively affect a statistically based data fusion method, like the Bayesian network, resulting in poor localization accuracy [2]. The study described in this paper explores the use of the reliability estimates to automatically stop the failed devices from contributing in the data fusion process, hence improving the overall robustness of the system. In this paper, we investigate the impact of 1) using a Bayesian network as the data fusion engine, 2) adding reliability estimates into the fusion engine, and 3) using reliability estimates to stop the failed localizers from contributing in the fusion process. [ABSTRACT FROM AUTHOR]

A frequency domain analysis of the influence of non- linear distortions on linear frequency response function measurements performed using multisine test signals is presented in this paper. The aim is to provide a closer insight into the mechanisms at work when multisine signals are subjected to static power-series nonlinearities. Emphasis is given to the behavior of a class of nonlinear distortions, termed hype II contributions, when different types of multisine signals are applied to a cubic, fifth-, seventh-, and ninth-order static nonlinear element The original results presented in this paper are a development of work conducted by the current authors as well as other authors in this area. [ABSTRACT FROM AUTHOR]

This paper describes a novel power system laboratory at Birla Vishvakarma Mahavidyalaya (B.V.M.) Engineering College, Gujarat, India, where every experiment was designed, wired and commissioned through senior design projects. The experiments on power system protection are especially unique in terms of their design and implementation and will be highlighted in this paper. They provide a real substation-like operating environment. Through these projects, the students, in addition to getting familiar with the fundamentals of protection, learned how different protection schemes are wired and how they operate in a real power system. For the institute, a quality laboratory was established at a low cost, which is a crucial issue for most colleges in many parts of the world. [ABSTRACT FROM AUTHOR]

This paper describes an efficient method of teaching impulse voltage testing of power transformers to undergraduate students of power system groups in electrical engineering departments, as a part of a high-voltage course for senior undergraduate students. The paper shows how to simulate the power transformer and impulse generator to teach students the basics of impulse voltage testing of power transformers and to practice analyzing the test results. In the first part of the paper, the effect of wave shaping of the voltage waveform is simulated to teach the behavior of the impulse generator, and in the second part, impulse voltage testing of a transformer is simulated. Evaluation of the simulation over several semesters with more than 80 students is very positive in terms of their developing confidence in an understanding of this test. [ABSTRACT FROM AUTHOR]

Parallel and distributed processing has been broadly applied to scientific and engineering computing, including various aspects of power system analysis. This paper first presents a distributed processing approach of reliability index assessment (RIA) for distribution systems. Then, this paper proposes a balanced task partition approach to achieve better efficiency. Next, the distributed processing of RIA is applied to reliability-based network reconfiguration (NR), which employs an algorithm combining local search and simulated annealing to optimize system reliability. Testing results are presented to demonstrate the speeded execution of RIA and NR with distributed processing. [ABSTRACT FROM AUTHOR]

An operating system course draws from a well-defined fundamental theory, but one needs to consider how more re- cent advances, not necessarily in the theory itself, can be applied to improve the course and the general body of knowledge of the student. The goal of this paper is to show how recent software engineering developments can be introduced to such a course to not only satisfy the theory requirements, but also make the theory more understandable. In particular, this paper focuses on how students can effectively learn the Unified Modeling Language, the object-oriented methodology, and the Java programming language in the context of an operating systems course. The goal is to form a systematic software engineering process for operating system design and implementation. [ABSTRACT FROM AUTHOR]

Voltage dips are often responsible for disrupting the operation of sensitive electronic equipment. In this paper, two solutions are presented to prevent sensitive equipment from disruptive operation. Both solutions make use of distributed generation systems to maintain the voltage across the equipment in the presence of voltage dips. The emphasis of this paper is on the transient re. spouse of both solutions to balanced as well as unbalanced voltage dips. Simulations have been carried out to provide a thorough analysis. [ABSTRACT FROM AUTHOR]

The focus of this paper is the modeling of materials that have both significant electric and magnetic losses, such as ferrites, using finite-difference time domain (FDTD). The primary contribution is identifying appropriate cell sizes when modeling these types of materials. It is shown that finite-differencing errors increase in lossy media compared to lossless media when sampling at the same number of cells per wavelength. Losses in a medium are defined by the ratio of the attenuation constant, α, to the phase constant, β, since that ratio accounts for all losses, whether they be electric or magnetic. In addition to a detailed finite-differencing error analysis, a simple approximation is given for selecting a cell size in a lossy material that will give the same finite-differencing error as ten cells per wavelength in a lossless material. This paper also presents a means for deriving pure real constitutive parameters from complex constitutive parameters. Being able to make such calculations is useful in cases where complex constitutive parameters are given for a material, and the FDTD model being used only accepts pure real constitutive parameters, as is the case for several contemporary models. Comparisons of theoretical and FDTD-modeled reflection and transmission show that the derived, real constitutive parameters are valid. [ABSTRACT FROM AUTHOR]

Most electrostatic discharge (ESD) generators are built in accordance with the IEC 61000-4-2 specifications. It is shown, that the voltage induced in a small loop correlates with the failure level observed in an ESD failure test on the systems comprised of fast CMOS devices, while rise time and derivative of the discharge current did not correlate well. The electric parameters of typical ESD generators and ESD generators that have been modified to reflect the current and field parameters of the human metal reference event are compared and the effect on the failure level of fast CMOS electronics is investigated. The consequences of aligning an ESD standard with the suggestions of the first paper, of this two-paper series, are discussed with respect to reproducibility and test severity. [ABSTRACT FROM AUTHOR]

Inductive learning of nonlinear functions plays an important role in constructing predictive models and classifiers from data. This paper explores a novel randomized approach to construct linear representations of nonlinear functions proposed elsewhere [14], [17]. This approach makes use of randomized codebooks, called the Genetic Code-Like Transformations (GCTs) for constructing an approximately linear representation of a nonlinear target function. This paper first derives some of the results presented elsewhere [17] in a more general context. Next, it investigates different probabilistic and limit properties of GCTs. It also presents several experimental results to demonstrate the potential of this approach. [ABSTRACT FROM AUTHOR]

This paper discusses some of the difficulties in the paper: "A BDD-based algorithm for reliability analysis of phased-mission systems" by X. Zang, H. Sun, and K. S. Trivedi. [ABSTRACT FROM AUTHOR]

The MPEG-4 standard enables the representation of video as a collection of objects. This paper describes an automatic system that exploits such a representation. Our system consists of two parts: real-time content extraction algorithms and a real-time multi-object rate control method. We present two approaches to content extraction: foreground segmentation based on two cameras and face segmentation based on a single camera. The main contributions of this paper are: 1) under a stereo camera setup, we improve a disparity estimation algorithm to obtain crisp and smooth boundaries of foreground objects; 2) for a single camera scenario, we propose a novel algorithm for face detection and tracking, combining facial color and structure information; and 3) we develop a constant-quality variable bitrate (CQ-VBR) control algorithm that guarantees the quality specification for each object obtained from the two content extraction methods. Both segmentation algorithms run in real-time on a low-cost media processor and have been tested extensively in various indoor environments. The CQ-VBR control algorithm is a useful tool for the evaluation of object-based coding. For low-bit-rate applications, we can achieve significant reduction in the overall bitrate, while maintaining the same visual quality of the foreground/face object as compared to conventional frame-based coding. Based on tests conducted on several sequences of different complexity levels, the bit-rate savings can be up to 48%. The satisfactory foreground segmentation (results presented) permits porting a live foreground object into arbitrary scenes to create composite video. [ABSTRACT FROM AUTHOR]

Speed is a great concern in the recursive shortest spanning tree (RSST) algorithm as its applications are focused on image segmentation and video coding, in which a large amount of data is processed. Several efficient RSST algorithms have been proposed in the literature, but the linking properties are not properly addressed and used in these algorithms and they are intended to produce a truncated RSST. This paper categorizes the linking process into three classes based on link weights. These linking processes are defined as the linking process for link weight equal to zero (LPLW-Z), the linking process for link weight equal to one (LPLW-O), and the linking process for link weight equal to real number (LFLW-R). We study these linking properties and apply them to an efficient RSST algorithm. The proposed efficient RSST algorithm is novel, as it makes use of linking properties, and its resulting shortest spanning tree is truly identical to that produced by the conventional algorithm. Our experimental results show that the percentages of links for the three classes are 17%, 27%, and 58%, respectively. This paper proposes a prediction method for LPLW-O, as a result of which the vertex weight of the next region can be determined by comparing sizes of the merging regions. It is also demonstrated that the proposed LPLW-O with prediction approach is applicable to the multiple-stage merging. Our experimental results show that the proposed algorithm has a substantial improvement over the conventional RSST algorithm. [ABSTRACT FROM AUTHOR]

This is one of a series of papers discussing the application and accuracy of different analysis techniques supporting the determination of industrial and commercial power system reliability and availability. There is a need recognized in the power industry to identify and utilize a standard tool, or a set of tools, to analyze the reliability of power systems. historically, the results of applying different reliability methodologies and tools varied significantly, and comparisons were difficult. The Reliability Analysis Techniques Working Group of the Gold Book (WEE Std. 493-1997) developed a standard network to enable comparison of analytical techniques. This paper describes the approach of simulations via reliability block diagrams as applied to the Gold Book standard network. Reliability indexes of the load points are presented, and are compared with ones obtained from other techniques in the series to determine the accuracy. [ABSTRACT FROM AUTHOR]

Current control in inverter-driven machine systems is the inner most component of the hierarchy of control loops. If the control of current in the machine is not fast and accurate then it is difficult, if not impossible, to build a high-performance drive system. Unfortunately, the implementation of current control in power electronic systems is not ideal. Practical effects can have a significant influence on its performance. This paper examines one of these effects, dead time, and considers the influence it has on the performance of predictive current controllers (PCCs). The paper presents analysis that shows that a PCC implicitly compensates for voltage loss due to dead time. Also, a modified PCC is introduced that reduces the zero-current-clamp problem caused by dead time. Simulation and experimental results are presented to verify the analysis and confirm the performance of the new algorithm. [ABSTRACT FROM AUTHOR]

Network flow problems cover a wide range of engineering and management applications. Many streamlined solution methods have been devised for solving different types of the problems. This paper investigates the network flow problems in that the arc lengths of the network are fuzzy numbers. Based on the integer-solution property of the network flow problem, the Yager ranking indices can be calculated for the fuzzy arcs to change the fuzzy formulation of the problem to a crisp formulation. Consequently, the conventional streamlined solution methods can still be applied to find an optimal solution. This optimal solution is proved to be the same as that derived from an exhaustive comparison of all possible solutions. Two examples, one shortest path and one transshipment, discussed in some previous studies illustrate that the method proposed in this paper is able to find the optimal solution. To show that the proposed method is useful in solving real-world problems, the problem of multimedia transmission over the Internet is exemplified. [ABSTRACT FROM AUTHOR]

This paper describes how HIV/AIDS education is being introduced into the curriculum of the Department of Electrical, Electronic, and Computer Engineering at the University of Pretoria, Pretoria, South Africa. Third- and fourth-year students were provided with an HIV/AIDS Educational CD developed at the university. Their knowledge of the subject was tested via two quizzes -- one written before they were exposed to the material on the CD and one after. In addition, a mathematical HIV/AIDS model is being incorporated into a third-year control systems course. This model is used to illustrate standard control systems engineering concepts, such as linearization, system stability, feedback, and dynamic compensation. This paper is an example of how topical nonengineering material can effectively be made part of a high-level undergraduate engineering course. Students benefit not only from the topical nature of the subject, hut also from an improved understanding of control engineering concepts which can be applied to many different fields. [ABSTRACT FROM AUTHOR]

This paper describes a wireless local area network laboratory project that provides senior and first-year graduate students in microwave engineering courses the opportunity to design, build, and test several passive microstrip components and integrate them into a working system. Students design filters, couplers, amplifiers, diode detectors, quarter-wave transformers, antennas, and stub matching networks in weekly labs that parallel-lectures in a one-semester microwave engineering course. This paper also describes simple inexpensive prototyping and testing methods that have been used in this course. Laboratory materials and technical details of the design are provided on the web for students and educators. [ABSTRACT FROM AUTHOR]

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material. [ABSTRACT FROM AUTHOR]

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material. [ABSTRACT FROM AUTHOR]

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material. [ABSTRACT FROM AUTHOR]

A testability transformation is a source-to-source transformation that aims to improve the ability of a given test generation method to generate test data for the original program. This paper introduces testability transformation, demonstrating that it differs from traditional transformation, both theoretically and practically, while still allowing many traditional transformation rules to be applied. The paper illustrates the theory of testability transformation with an example application to evolutionary testing. An algorithm for flag removal is defined and results are presented from an empirical study which show how the algorithm improves both the performance of evolutionary test data generation and the adequacy level of the test data so-generated. [ABSTRACT FROM AUTHOR]

This paper describes a knowledge-based approach to automate a software design method for concurrent systems. The approach uses multiple paradigms to represent knowledge embedded in the design method. Semantic data modeling provides the means to represent concepts from a behavioral modeling technique, called Concurrent Object-Based Real-time Analysis (COBRA), which defines system behavior using data/control flow diagrams. Entity-Relationship modeling is used to represent a design metamodel based on a design method, called Concurrent Design Approach for Real-Time Systems (CODARTS), which represents concurrent designs as software architecture diagrams, task behavior specifications, and module specifications. Production rules provide the mechanism for codifying a set of CODARTS heuristics that can generate concurrent designs based on semantic concepts included in COBRA behavioral models and on entities and relationships included in CODARTS design metamodels. Together, the semantic data model, the entity-relationship model, and the production rules, when encoded using an expert-system shell, compose CODA, an automated designer's assistant. Other forms of automated reasoning, such as knowledge-based queries, can be used to check the correctness and completeness of generated designs with respect to properties defined in the CODARTS design metamodel. CODA is applied to generate 10 concurrent designs for four real-time problems. The paper reports the degree of automation achieved by CODA. The paper also evaluates the quality of generated designs by comparing the similarity between designs produced by CODA and human designs reported in the literature for the same problems. In addition, the paper compares CODA with four other approaches used to automate software design methods. [ABSTRACT FROM AUTHOR]

Requirements engineering is concerned with the elicitation of high-level goals to be achieved by the envisioned system, the refinement of such goals and their operationalization into specifications of services and constraints and the assignment of responsibilities for the resulting requirements to agents such as humans, devices, and software. Requirements engineering processes often result in goals, requirements, and assumptions about agent behavior that are too ideal; some of them are likely not to be satisfied from time to time in the running system due to unexpected agent behavior. The lack of anticipation of exceptional behaviors results in unrealistic, unachievable, and/or incomplete requirements. As a consequence, the software developed from those requirements will not be robust enough and will inevitably result in poor performance or failures, sometimes with critical consequences on the environment. This paper presents formal techniques for reasoning about obstacles to the satisfaction of goals, requirements, and assumptions elaborated in the requirements engineering process. A first set of techniques allows obstacles to be generated systematically from goal formulations and domain properties. A second set of techniques allows resolutions to be generated once the obstacles have been identified thereby. Our techniques are based on a temporal logic formalization of goals and domain properties; they are integrated into an existing method for goal-oriented requirements elaboration with the aim of deriving more realistic, complete, and robust requirements specifications. A key principle in this paper is to handle exceptions at requirements engineering time and at the goal level, so that more freedom is left for resolving them in a satisfactory way. The various techniques proposed are illustrated and assessed in the context of a real safety-critical system. [ABSTRACT FROM AUTHOR]

An electrical and mechanical design process for a traction motor in a hybrid bus application is studied. Usually, the design process of an electric machine calls for close cooperation between various engineering disciplines. Compromises may be required to satisfy the boundary conditions of electrical, thermal, and mechanical performances. From the mechanical point of view, the stress values and the safety factors should be at a reasonable level and the construction lifetime predicted by a fatigue analysis. In a vehicle application, the motor has to be capable of generating high torque when accelerating, and in normal operation, the losses of the machine should be low to be able to cool the machine. Minimization of the no-load iron losses becomes a very important electrical design requirement if the traction motor and the generator are mechanically connected with an internal combustion engine when it is operating as the only source of torque. The manufacturing costs of the motor are also taken into account in this paper. [ABSTRACT FROM PUBLISHER]

Collocated adaptive control of underactuated mechanical systems is still a concern for the control community. The main difficulty comes from the nonlinearity of the collocated inverse dynamics with respect to the base parameters, which forbids the direct application of classical adaptive control schemes. This paper extends and encompasses the Slotine's adaptive control, which was developed for fully actuated mechanical systems, to stabilize the collocated state space of an underactuated mechanical system. The key point is to define the sliding variable as the difference between the system's velocity and an exogenous state whose dynamics is considered as control input. We first revisit the Slotine's result in view of this definition and then show how to extend it to the underactuated case. Stability and convergence of time-varying reference trajectories for the collocated dynamics are shown to be in the sense of Lyapunov. Global well-posedness of the control laws is achieved by means of a new algebraic property of the mass matrix. Simulations, comparisons to existing control strategies, and experimental results on a two-link manipulator verify the soundness of the proposed approach. [ABSTRACT FROM PUBLISHER]

The China fusion engineering test reactor (CFETR) is an ITER-like tokamak system for fusion energy development. It could output 50-200 MW fusion power in phase I for demonstrating power generation with complete structure of fusion power plant, and 1 GW output power can be expected in phase II. Its ITER-like HV substation receives power from the 500 kV transmission grid for powering its pulsed power electric network (PPEN) and steady-state electric power network (SSEN). This paper describes the concept design of the electric power system, with emphasis on its turbine generator implemented with flexible doubly fed induction generator (DFIG). DFIG has ride through ability during the plasma-off period. Its capability diagram is configured to analyze its operation range. Similar to ITER, the CFETR also requires about 1 GVar reactive power to be compensated. Based on this requirement, the generator is expected to generate part of reactive power to compensate and stabilize the local power network. [ABSTRACT FROM PUBLISHER]

This paper analyzes the influences of the factors in a capacitor-driven multi-stage synchronous induction coilgun (SICG) and optimal combination of the design parameters based on orthogonal experiment design (OED). Finite element transient solver is used to calculate the motion characteristics of a multi-stage SICG. The muzzle speed is set to be the target of the optimization. System parameters (factors), levels and orthogonal array (OA) are determined by the order. Three optimization schemes are compared, including stage-by-stage optimization, section optimization and full optimization. Optimal combination of the three-stage SICG is obtained, as well as important order of factors. It shows that a set of comparatively better parameters and relatively higher efficiency could be achieved through orthogonal optimum. Wire diameter and coil diameter are the most important factors that influence the system efficiency of the launcher. Besides them, length of coil, trigger position and number of turns have less influence for the system in the important order. Section optimization could reduce the amount of computations compared to full optimization and a set of comparatively better parameters and relatively higher efficiency could be achieved. It is suggested to optimize a multi-stage SICG. How to choose the factors from lots of parameters is according to the engineering practice. Improper choices of the value in levels may cause unable to reach an optimum. The conclusion will be useful for coilgun design. [ABSTRACT FROM PUBLISHER]

A wide range of inconsistencies can arise during requirements engineering as goals and requirements are elicited from multiple stakeholders. Resolving such inconsistencies sooner or later in the process is a necessary condition for successful development of the software implementing those requirements. The paper first reviews the main types of inconsistency that can arise during requirements elaboration, defining them in an integrated framework and exploring their interrelationships. It then concentrates on the specific case of conflicting formulations of goals and requirements among different stakeholder viewpoints or within a single viewpoint. A frequent, weaker form of conflict called divergence is introduced and studied in depth. Formal techniques and heuristics are proposed for detecting conflicts and divergences from specifications of goals/ requirements and of domain properties. Various techniques are then discussed for resolving conflicts and divergences systematically by introduction of new goals or by transformation of specifications of goals/objects toward conflict-free versions. Numerous examples are given throughout the paper to illustrate the practical relevance of the concepts and techniques presented. The latter are discussed in the framework of the KAOS methodology for goal-driven requirements engineering. [ABSTRACT FROM AUTHOR]

In this paper, we present a case study of evolution (or vertical reuse) in the domain of visual interactive software tools. We introduce an architecture suitable for this purpose, called orthogonal architecture. The paper describes the architecture itself, the reverse engineering process by which it was obtained, and the forward engineering process by which it was evolved. [ABSTRACT FROM AUTHOR]

Software productivity has been steadily increasing over the past 30 years, but not enough to close the gap between the demands placed on the software industry and what the state of the practice can deliver [22], [39]; nothing short of an order of magnitude increase in productivity will extricate the software industry from its perennial crisis [39], 1671. Several decades of intensive research in software engineering and artificial intelligence left few alternatives but software reuse as the (only) realistic approach to bring about the gains of productivity and quality that the software industry needs. In this paper, we discuss the implications of reuse on the production, with an emphasis on the technical challenges. Software reuse involves building software that is reusable by design and building with reusable software. Software reuse includes reusing both the products of previous software projects and the processes deployed to produce them, leading to a wide spectrum of reuse approaches, from the building blocks (reusing products) approach, on one hand, to the generative or reusable processor (reusing processes), on the other 1681. We discuss the implication of such approaches on the organization, control, and method of software development and discuss proposed models for their economic analysis. Software reuse benefits from methodologies and tools to: 1) build more readily reusable software and 2) locate, evaluate, and tailor reusable software, the last being critical for the building blocks approach. Both sets of issues are discussed in this paper, with a focus on application generators and OO development for the first and a thorough discussion of retrieval techniques for software components, component composition (or bottom-up design), and transformational systems for the second. We conclude by highlighting areas that, in our opinion, are worthy of further investigation. [ABSTRACT FROM AUTHOR]

The interpretations of logical expressions found in most introductory textbooks are not suitable for use in software engineering applications because they do not deal with partial functions. More advanced papers and texts deal with partial functions in a variety of complex ways. This paper proposes a very simple change to the classic interpretation of predicate expressions, one that defines their value for all values of all variables, yet is almost identical to the standard definitions. It then illustrates the application of this interpretation in software documentation. [ABSTRACT FROM AUTHOR]

The paper deals with the performance analysis of parallel algorithms and systems. For these, numerical solution methods quickly show their limits because of the enormous state-space growth. The proposed methodology and software tool (LISPACK, an acronym for List-manipulation Parallel-modeling Package) uses string manipulation, lumping, and recursive elimination as a means for the definition of the large Markovian process, its restructuring and efficient solution. Initially, the enormous stage space is conveniently collapsed and the large transition matrix is reduced. Subsequently, the reduced matrix is recursively block banded, and an efficient recursive, symbolic Gauss elimination is applied. No relevant costs are incurred for the state-space collapsing and restructuring, nor for the matrix block banding. The analysis of a typical parallel system and algorithm model is developed as a case study, to discuss the features of the method. The paper has two contributions. The first, symbolic-approach methodology, is proposed for the performance analysis of parallel algorithms and systems. Second, a tool is introduced that exploits the capabilities of the symbolic approach in the solution of parallel models, where the numerical techniques reveal their limits. [ABSTRACT FROM AUTHOR]

Software size estimates provide a basis for soft- ware cost estimation during software development. Hence, it is important to measure the system size reliably as early as possible, i.e., during the requirements specification. Two best known specification level metrics are Albrecht's Function Points and DeMarco's Function Bang. One problem in using these metrics has been that there are only few tools that can calculate them during the specification phase. We have built one such tool. Another problem has been that no research data is available how these metrics correlate with one another. The paper compares these two metrics by a simulation study in which automatically generated randomized dataflow diagrams (DED's) were used as a statistical sample to count automatically function points and function bang in a built CASE environment. These value counts were correlated statistically using correlation coefficients and regression analysis. The simulation study permits sufficient variation in the base material to cover most types of system specifications. Moreover, it allows sufficient sampling sizes to make statistical analysis of data. The obtained results show that in certain cases there is a relatively good statistical correlation between these metrics. No overall general correlation exists, however. The paper does not show which one of the two metrics fares better as a size metric. Yet, our study suggests to use in many cases Function Bang metric, because its automatic calculation is simpler and depends less on judgement. Moreover, the study demonstrates that correlations depend upon a system type. This implies that in software projects one must be careful with size estimates while using these metrics. In order to know when one needs to calibrate the size estimate we need to develop algorithms which help to detect logical system types and make adjustments accordingly. The results also point out the need of empirical research in which we can better derive the connection between specification level metrics and the number of lines of code. [ABSTRACT FROM AUTHOR]

In this paper we attempt to formalize some properties which any reasonable control-flow complexity measure must satisfy, and our work is in the same spirit of an earlier paper by Weyuker in this TRANSACTIONS [18]. Since large programs are often built by sequencing and nesting of simpler constructs, we explore how control-flow complexity measures behave under such compositions. Our analysis reveals the strengths and weaknesses of some of the existing control flow complexity measures. [ABSTRACT FROM AUTHOR]

This paper describes a new method, called mutant unification, for high-performance software testing. The method is aimed at supporting program mutation on parallel machines based on the Single Instruction Multiple Data stream (SIMD) paradigm. Several parameters that affect the performance of unification have been identified and their effect on the time to completion of a mutation test cycle and speedup has been studied. Program mutation analysis provides an effective means for determining the reliability of large software systems. It also provides a systematic method for measuring the adequacy of test data. However, it is likely that testing large software systems using mutation is computation bound and prohibitive on traditional sequential machines. Current implementations of mutation tools are unacceptably slow and are only suitable for testing relatively small programs. The unification method reported in this paper provides a practical alternative to the current approaches. It also opens up a new application domain for SIMD machines. [ABSTRACT FROM AUTHOR]

There are two main contributions of this paper. First, this paper introduces the concept of a processor working set (pws) as a single value parameter for characterizing the parallel program behavior. Through detailed experimental studies of different algorithms on a transputer-based multiprocessor machine, it is shown that the pws is indeed a robust measure for characterizing the workload of a multiprocessor system. Small deviations in the performance of algorithms arising due to communication overhead are captured in this parameter. The second contribution of this paper relates to the study of static processor allocation strategies. It is shown that processor allocation strategies based on the pws provide significantly better throughput-delay characteristics. The robustness of pws is further demonstrated by showing that allocation policies that allocate processors more than the pws are inferior in performance to those that never allocate more than the pws—even at a moderately low load. Based on the results, a simple static allocation policy that allocates the pws at low load and adaptively fragments at high load to one processor per job is proposed. This allocation strategy is shown to possess the best throughput-delay characteristic over a wide range of loads. [ABSTRACT FROM AUTHOR]

The concept of multiway rendezvous has been proposed to implement synchronous communication among an arbitrary number of concurrent, asynchronous processes. The synchronization and exclusion problems associated with implementing multiway rendezvous are expressed succinctly in the context of the committee coordination problem. A variety of techniques to solve the synchronization and exclusion problems may be combined to design algorithms for the committee coordination problem. This paper presents a simple solution for the problem and shows how it can be implemented to develop a family of algorithms. The algorithms use message counts to solve synchronization and solve the exclusion problem by using a circulating token, or by using auxiliary resources as in the solutions for the dining or drinking philosophers problems. The paper also presents the results of a simulation study on the performance of the algorithms. The experiments measured the response time and message complexity of each algorithm as a result of variations in different model parameters including network topology and level of conflict in the system. The results from the study show that the response time for algorithms proposed in this paper is significantly better than an existing algorithm, whereas the message complexity is considerably worse. [ABSTRACT FROM AUTHOR]

For the development of communications software com- posed of many modules, protocol validation is essential to detect errors in the interactions among the modules. A number of protocol validation techniques were proposed in the past, but the validation time required by these techniques is too long for many actual protocols. This paper proposes a new fast protocol validation technique to overcome this drawback. The proposed technique is to construct the minimum acyclic form of state transitions in individual processes of the protocol, and to detect protocol errors such as system deadlocks and channel overflows fast. This paper also presents a protocol validation system based on the proposed technique to confirm its feasibility and shows validation results for some actual protocols obtained with this system. As a result, the protocol validation system is expected to contribute to a great extent to the improvement of the productivity in development and maintenance of communications software. [ABSTRACT FROM AUTHOR]

ALMA is an environment kernel supporting the elaboration, analysis, documentation, and maintenance of the various products developed during an entire software lifecycle. Its central component is an environment database n which properties about software objects and relations are collected. These properties include texts written in various formalisms. Two kinds of tools are provided: 1) high- level tools for updating, querying, reporting and maintaining multiple versions of software objects and relations consistently in the database, and 2) syntax-directed tools like structural editors for manipulating the formal texts attached to software objects and relations in the database. A basic feature of the ALMA kernel is its genericity. Tools of the first kind are parameterized on software lifecycle models while tools of the second kind are parameterized on formalisms. Instantiated versions of them for specific models arid formalisms are generated by a meta-environment, which also generates the environment database structure tailored to the desired lifecycle model. This paper concentrates on the database support meta-system and the instantiated database support 5) stems it generates. Our main concern is to discuss the architectural design decisions we made and the mechanisms we introduced for achieving parameterization on lifecycle models. In particular, we describe the entity-relationship meta-model we designed for meta-defining a particular lifecycle model as input to the meta-system. This meta-model is an extension of standard entity-relationship models in that n-ary relations can have attributes, they can be defined on unions of entity types, type specialization with multiple inheritance is supported, and a mechanism is provided for defining views yielding different environment subdatabases associated with different classes of users and/or tools. The crucial role played by this meta-model will be stressed all along the paper. [ABSTRACT FROM AUTHOR]

It is being recognized that recent programming environments have made significant progress towards improving the programming process. In adhering to this goal of software engineering, this paper introduces a new basis for programming environments. This basis encourages development of software in fragments of various types, called fragtypes. Fragtypes range from a simple expression type to a complete subsystem type. As a result, they are suited to the development of software in an enlarged scope that includes both programming in the small and programming in the large; The paper shows how new proposed operations on fragtypes can achieve unusual effects on the software development process. Fragtypes and their associated construction rules form the basis of the programming environment MUPE- 2, which is currently under development at McGill University. The target and the implementation language of this environment is the programming language Modula-2. [ABSTRACT FROM AUTHOR]

One of the best features of the UNIXTM Shell is that it provides a framework which can be used to build complex programs by interconnecting existing simple programs. However, it is limited to linear combinations of programs, and building of more complex programs must be accomplished by executing sequences of commands. This paper introduces Backus' FP (Functional Programming) as an alter- native command language for UNIX. In FP, programs are true functions and another distinctive feature of FP languages is that they contain functional forms, which are constructs for combining programs to build new programs. Also, the functional style of programming provides a natural way of exploiting parallel machine architecture. In this paper it is shown how to enhance the power of the UNIX Shell by the inclusion of the FP functional forms. The FP-Shell is fully implemented in "C" under UNIX. It interprets standard UNIX commands as FP primitive functions and standard UNIX files as FP system objects. It also serves as a framework for the study of functional programming languages. [ABSTRACT FROM AUTHOR]

This paper discusses the goals and methods of the Toolpack project and in this context discusses the architecture and design of the software system being produced as the focus of the project. Toolpack is presented as an experimental activity in which a large software tool environment is being created for the purpose of general distribution and then careful study and analysis. The paper begins by explaining the motivation for building integrated tool sets. It then proceeds to explain the basic requirements that an integrated system of tools must satisfy in order to be successful and to remain useful both in practice and as an experimental object. The paper then summarizes the tool capabilities that will be incorporated into the environment. It then goes on to present a careful description of the actual architecture of the Toolpack integrated tool system. Finally the Toolpack project experimental plan is presented, and future plans and directions are summarized. [ABSTRACT FROM AUTHOR]

One of the most important problems faced by software developers and users is the prediction of the size of a programming system and its development effort. As an alternative to "size," one might deal with a measure of the "function" that the software is to perform. Albrecht [1] has developed a methodology to estimate the amount of the "function" the software is to perform, in terms of the data it is to use (absorb) and to generate (produce). The "function" is quantified as "function points," essentially, a weighted sum of the numbers of "inputs," "outputs," master files," and "inquiries" provided to, or generated by, the software. This paper demonstrates the equivalence between Albrecht's external input/output data flow representative of a program (the "function points" metric) and Halstead's [2] "software science" or "software linguistics" model of a program as well as the "soft content" variation of Halstead's model suggested by Gaffney [7]. Further, the high degree of correlation between "function points" and the eventual "SLOC" (source lines of code) of the program, and between "function points" and the work-effort required to develop the code, is demonstrated. The "function point" measure is thought to be more useful than "SLOC" as a prediction of work effort because "function points" are relatively easily estimated from a statement of basic requirements for a program early in the development cycle. The strong degree of equivalency between "function points" and "SLOC" shown in the paper suggests a two-step work-effort validation procedure, first using "function points" to estimate "SLOC," and then using "SLOC" to estimate the work-effort. This approach would pro- vide validation of application development work plans and work-effort estimates early in the development cycle. The approach would also more effectively use the existing base of knowledge on producing "SLOC" until a similar base is developed for "function points." The paper assumes that the reader is familiar with the fundamental theory of "software science" measurements and the practice of validating estimates of work-effort to design and implement software applications (programs). If not, a review of [1] -[3] is suggested. [ABSTRACT FROM AUTHOR]

Conservation voltage reduction (CVR) and distributed-generation (DG) integration are popular strategies implemented by utilities to improve energy efficiency. This paper investigates the interactions between CVR and DG placement to minimize load consumption in distribution networks, while keeping the lowest voltage level within the predefined range. The optimal placement of DG units is formulated as a stochastic optimization problem considering the uncertainty of DG outputs and load consumptions. A sample average approximation algorithm-based technique is developed to solve the formulated problem effectively. A multiple replications procedure is developed to test the stability of the solution and calculate the confidence interval of the gap between the candidate solution and optimal solution. The proposed method has been applied to the IEEE 37-bus distribution test system with different scenarios. The numerical results indicate that the implementations of CVR and DG, if combined, can achieve significant energy savings. [ABSTRACT FROM AUTHOR]

This paper presents a novel time-domain fault location algorithm on HVDC transmission lines. The Bergeron line model is adopted to construct a time-domain fault location equation, considering unsynchronized two-end measurement and uncertain line parameters. The zero time reference point is set to the sample point of arrival at each end for the traveling wave-head. Time-tags of all sample points change with the zero time reference. So the time difference of two-end measurements has changed also, and equals the time difference between arrivals at two ends for the traveling wave-head. That makes it possible to mix the traveling wave theory with the Bergeron time-domain fault location method. Besides, the ratio coefficient of wave velocities between different frequencies and digital band-pass filter are presented for better performance of the proposed method. Simulations and tests demonstrate that the proposed method can locate faults accurately on the HVDC lines even in the case of loss of signals from GPS. [ABSTRACT FROM AUTHOR]