bluuebunny/crossref_metadata_2025_split huggingface dataset:
SPECIFICATION AND ANALYSIS OF REAL-TIME SYSTEMS USING CSP AND PETRI NETS
Authors: KAVI KRISHNA M. , SHELDON FREDERICK T. , REED SHERMAN 
Published: September 2004

Formal methods such as CSP (Communicating Sequential Processes) are widely used for reasoning about concurrency, communication, safety, and liveness issues. Some of these models have been extended to permit reasoning about real-time constraints. Yet, the research in formal specification and verification of complex systems has often ignored the specification of stochastic properties of the system under study. We are developing methods and tools to permit stochastic analyses of CSP-based specifications. Our basic objective is to evaluate candidate design specifications by converting formal systems descriptions into the information needed for analysis. In doing so, we translate a CSP-based specification into a Petri net which is analyzed to predict system behavior in terms of reliability and performability as a function of observable parameters (e.g., topology, fault-tolerance, deadlines, communications, and failure categories). This process can give insight into further refinements of the original specification (i.e., identify potential failure processes and recovery actions). Relating the parameters needed for performability analysis to user level specifications is essential for realizing systems that meet user needs in terms of cost, functionality, and other nonfunctional requirements. An example translation is given (in addition, some general examples of CSP → Petri net translations can be viewed in Appendix A). Based on this translation, we report both the discrete and continuous time Markovian analysis which provides reliability predictions for the candidate specification. The term “CSP-based” is used here to distinguish between the notation of Hoare’s original CSP and our textual representations which are similar to occum. Our CSP-based grammar does not restrict consideration of the properties of CSP (traces, refusal sets, livelock, etc.), but we are not considering those properties. We are only interested that the structural properties are preserved. We define performability as a measure of the system’s ability in meeting deadlines, in the presence of failures and variance in task execution times.
A DEVELOPMENT ENVIRONMENT FOR HARD REAL-TIME APPLICATIONS
Authors: ANCILOTTI PAOLO , BUTTAZZO GIORGIO , NATALE MARCO DI , SPURI MARCO 
Published: September 2004

In this paper, we describe an integrated environment to assist the development of hard real-time applications. It includes an interactive graphic interface which allows the user to describe the application requirements according to three hierarchical levels: the application level, the component level, and the object level. The development model we propose is based on an iterative process in which the real-time scheduling support is considered since the beginning of the design phases. Our graphic environment integrates several tools to analyse, test, and simulate the real-time application under development. In particular, the tools we have implemented are: a Design Tool, to describe the structure of the application, a Schedulability Analyser Tool (SAT), to verify off-line the feasibility of the schedule of a critical task set, a Scheduling Simulator, to test the average behaviour of the application, and a Maximum Execution Time (MET) estimator to bound the worst case duration of each task.
MODELING AND DEVELOPING REAL-TIME CONCURRENT APPLICATIONS
Authors: BRUNO GIORGIO , AGARWAL RAKESH 
Published: September 2004

The development of concurrent applications, which consist of several parallel, often distributed, activities that communicate and synchronize with each other, presents challenging logical and technological issues. In the common practice, technological aspects, which are related to the definition of concurrent processes as well as of their interactions, often place constraints on the logical ones. Consequently, the flexibility that could be attained during design is reduced and, further, an actual implementation where both aspects are deeply intermixed is usually obtained. This paper first presents an expressive and flexible language based on object-oriented high-level nets, which allows designers to naturally represent concurrency and synchronization. Then, it illustrates a powerful software engineering environment, CAB (Concurrent Applications Builder), which supports the building and the simulation/animation of models as well as the automatic generation of applications from models (by transforming the model’s objects into implementation processes). A case study from an actual project for automatic toll collection in motor-ways is illustrated.
OBJECT EXTENSIONS TO Z: A SURVEY
Authors: ACHEE B.L. , CARVER DORIS L. 
Published: September 2004

Formal specification languages provide assistance to solving the problem of high maintenance costs caused by ineffective communication of a system’s requirements. Using a sound mathematical basis, a formal specification language provides a precise and definitive system description that can serve as a binding contract. Additionally, the integration of the object-oriented paradigm with a formal specification language provides increased potential for software reuse, conceptually cleaner specifications and a framework for defining interfaces. To this end, there has been significant work done to extend existing specification languages to allow object-oriented specifications. This paper provides a comparison of such object-oriented specification languages, specifically, those extending Z. The paper is organized into five major sections. After a brief introduction to the concepts of formal specification languages and Z, a simple library system is defined and used as an example throughout the paper. Each of the object-oriented specification languages is introduced and classified as either using Z in an object-oriented style or providing a true object-oriented extension of Z. For each language, the specification of the example library system is presented following a brief overview of the language’s features. An in-depth comparison is made of each of the languages which provide a true object-oriented extension of Z.
PARFORMAN—AN ASSERTION LANGUAGE FOR SPECIFYING BEHAVIOR WHEN DEBUGGING PARALLEL APPLICATIONS
Authors: AUGUSTON M. , FRITZSON P. 
Published: September 2004

PARFORMAN (PARallel FORMal ANnotation language) is a high-level specification language for expressing intended behavior or known types of error conditions when debugging or testing parallel programs. Models of intended or faulty target program behavior can be succinctly specified in PARFORMAN. These models are then compared with the actual behavior in terms of execution traces of events, in order to localize possible bugs. PARFORMAN can also be used as a general language for expressing computations over target program execution histories. PARFORM AN is based on a precise model of target program behavior. This model, called H-space (History-space), is formally defined through a set of general axioms about three basic relations, which may or may not hold between two arbitrary events: they may be sequentially ordered (SEQ), they may be parallel (PAR), or one of them might be included in another composite event (IN). The general notion of composite event is exploited systematically, which makes possible more powerful and succinct specifications. The notion of event grammar is introduced to describe allowed event patterns over a certain application domain or language. Auxiliary composite events such as Snapshots are introduced to be able to define the notion “occurred at the same time” at suitable levels of abstraction. Finally, patterns and aggregate operations on events are introduced to make possible short and readable specifications. In addition to debugging and testing, PARFORMAN can also be used to specify profiles and performance measurements.
AN ALGORITHM FOR DRAWING A HIERARCHICAL GRAPH
Authors: EADES PETER , LIN XUEMIN , TAMASSIA ROBERTO 
Published: September 2004

Hierarchical graphs appear in several graph drawing applications, where nodes are assigned layers for semantic reasons. More importantly, general methods for drawing directed graphs usually begin by transforming the input digraph into a hierarchical graph, then applying a hierarchical graph drawing algorithm. This paper introduces the Degree Weighted Barycentre (DWB) algorithm for drawing hierarchical graphs. We show that drawings output by DWB satisfy several important aesthetic criteria: under certain connectivity conditions, they are planar, convex, and symmetric whenever such drawings are possible. The algorithm can be implemented as a simple Gauss — Seidel iteration.
PLANAR UPWARD TREE DRAWINGS WITH OPTIMAL AREA
Authors: GARG ASHIM , GOODRICH MICHAEL T. , TAMASSIA ROBERTO 
Published: September 2004

Rooted trees are usually drawn planar and upward, i.e., without crossings and with-out any parent placed below its child. In this paper we investigate the area requirement of planar upward drawings of rooted trees. We give tight upper and lower bounds on the area of various types of drawings, and provide linear-time algorithms for constructing optimal area drawings. Let T be a bounded-degree rooted tree with N nodes. Our results are summarized as follows: • We show that T admits a planar polyline upward grid drawing with area O(N), and with width O(Nα) for any prespecified constant a such that 0<α<1. • If T is a binary tree, we show that T admits a planar orthogonal upward grid drawing with area O (N log log N). • We show that if T is ordered, it admits an O(N log N)-area planar upward grid drawing that preserves the left-to-right ordering of the children of each node. • We show that all of the above area bounds are asymptotically optimal in the worst case. • We present O(N)-time algorithms for constructing each of the above types of drawings of T with asymptotically optimal area. • We report on the experimentation of our algorithm for constructing planar polyline upward grid drawings, performed on trees with up to 24 million nodes.
SCALABLE PARALLEL COMPUTATIONAL GEOMETRY FOR COARSE GRAINED MULTICOMPUTERS
Authors: DEHNE FRANK , FABRI ANDREAS , RAU-CHAPLIN ANDREW 
Published: September 2004

We study scalable parallel computational geometry algorithms for the coarse grained multicomputer model: p processors solving a problem on n data items, were each processor has O(n/p)≫O(1) local memory and all processors are connected via some arbitrary interconnection network (e.g. mesh, hypercube, fat tree). We present O(Tsequential/p+Ts(n, p)) time scalable parallel algorithms for several computational geometry problems. Ts(n, p) refers to the time of a global sort operation. Our results are independent of the multicomputer’s interconnection network. Their time complexities become optimal when Tsequential/p dominates Ts(n, p) or when Ts(n, p) is optimal. This is the case for several standard architectures, including meshes and hypercubes, and a wide range of ratios n/p that include many of the currently available machine configurations. Our methods also have some important practical advantages: For interprocessor communication, they use only a small fixed number of one global routing operation, global sort, and all other programming is in the sequential domain. Furthermore, our algorithms use only a small number of very large messages, which greatly reduces the overhead for the communication protocol between processors. (Note however, that our time complexities account for the lengths of messages.) Experiments show that our methods are easy to implement and give good timing results.
CORRECTNESS PROOF OF A GEOMETRIC CONSTRAINT SOLVER
Authors: FUDOS IOANNIS , HOFFMANN CHRISTOPH M. 
Published: September 2004

We present a correctness proof of a graph-directed variational geometric constraint solver. First, we prove that the graph reduction that establishes the sequence in which to apply the construction steps defines a terminating confluent reduction system, in the case of well-constrained graphs. For overconstrained problems there may not be a unique normal form. Underconstrained problems, on the other hand, do have a unique normal form. Second, we prove that all geometric solutions found using simple root-selection rules must place certain triples of elements in the same topological order, no matter which graph reduction sequence they are based on. Moreover, we prove that this implies that the geometric solutions derived by different reduction sequences must be congruent. Again, this result does not apply to overconstrained problems.
INEXACT NEWTON METHODS FOR THE STEADY STATE ANALYSIS OF NONLINEAR CIRCUITS
Authors: GUGLIELMI NICOLA 
Published: September 2004

In this paper numerical problems arising from steady state analysis of nonlinear circuits with quasiperiodic excitation are discussed. The approach we consider is based on the piecewise harmonic balance techniques8,9 (HB), a methodology which has its theoretical foundations in Galerkin's procedure (see the paper by Urabe12). The original problem, which can be expressed in the form of a system of integro-differential equations in the time domain, is changed into a nonlinear algebraic system through a natural projection technique. Thus, one of the main issues we have investigated consists in the numerical solution of the specific nonlinear algebraic problem.
RKH SPACE METHODS FOR LOW LEVEL MONITORING AND CONTROL OF NONLINEAR SYSTEMS
Authors: COVER ALAN , RENEKE JAMES , FRYER MICHAEL , LENHART SUZANNE , PROTOPOPESCU VLADIMIR 
Published: September 2004

A monitor or controller is smart provided that the device is equipped with local computational resources for analyzing data, detecting changes, and making decisions. The problem for the monitoring function is to design algorithms to flag model shifts for dynamic systems in a context requiring many interacting system components and system reconfigurations. The problem for the control function is to improve system performance by updating control feedbacks after the model shift has been detected. Therefore it is desirable that smart monitors and controllers be adaptive and update with minimal intervention from a central director. We present here an approach to designing smart monitoring and control devices based on a stochastic linearization of the system whose dynamics is noisy and unknown. This linearization is obtained by factoring the discrete system covariance matrix, estimated from observations, and applying reproducing kernel Hilbert space techniques. The method is nonparametric which allows the smart devices to operate with only a low level logic.
SECOND-ORDER SCHEME FOR THE SPATIALLY HOMOGENEOUS BOLTZMANN EQUATION WITH MAXWELLIAN MOLECULES
Authors: STRUCKMEIER JENS , STEINER KONRAD 
Published: September 2004

In the standard approach particle methods for the Boltzmann equation are obtained using an explicit time discretization of the spatially homogeneous Boltzmann equation. This kind of discretization leads to a restriction on the discretization parameter as well as on the differential cross-section in the case of the general Boltzmann equation. Recently, construction of an implicit particle scheme for the Boltzmann equation with Maxwellian molecules was shown. This paper combines both approaches using a linear combination of explicit and implicit discretizations. It is shown that the new method leads to a second-order particle method when using an equiweighting of explicit and implicit discretization.
ON THE STABILITY OF A STELLAR STRUCTURE IN ONE DIMENSION
Authors: DUCOMET B. 
Published: September 2004

We describe in this paper the stability of the interface in a free-boundary problem for a self-gravitating gas in one space dimension, with an external pressure P, and a Fourier coefficient λ, for the thermal flux. In the first part, we consider the pure gaseous limit (perfect gas), and we find different possible asymptotic behaviors: if λ > 0, the gas tends to collapse; if λ = 0, we show that, when P > 0, the solution converges, for large time to the isothermal solution of the corresponding stationary problem, while for P = 0, the system is unstable, and the gas tends to fill all the space. In the second part, we consider the same problem for the pure radiative limit (photon gas), and we show that analogous asymptotics hold.
ACCURATE PARALLEL INTEGRATION OF LARGE SPARSE SYSTEMS OF DIFFERENTIAL EQUATIONS
Authors: ESTEP DONALD J. , WILLIAMS ROY D. 
Published: September 2004

We describe a MIMD parallel code to solve a general class of ordinary differential equations, with particular emphasis on the large, sparse systems arising from space discretization of systems of parabolic partial differential equations. The main goals of this work are sharp bounds on the accuracy of the computed solution and flexibility of the software. We discuss the sources of error in solving differential equations, and the resulting constraints on time steps. We also discuss the theory of a posteriori error analysis for the Galerkin finite element methods, and its implementation in error control and estimation. The software is designed in a matrix-free fashion, which enables the solver to effectively tackle large sparse systems with minimal memory consumption and an easy and natural transition to MIMD (distributed memory) parallelism. In addition, there is no need for the choice of a particular representation of a sparse matrix. All memory is dynamically allocated, with a new expandable array object used for archiving results. The implicit solution of the discrete equations is carried out by replaceable modules: the nonlinear solver module may be a full Newton scheme or a quasi-Newton; these in turn are implemented with a linear solver, for which we have used both a direct solver and QMR, an iterative (Krylov space) method. Three computations are presented: the Lorenz system, which has dimension three and the discretized versions of the (partial-differential) bistable equation in one and two dimensions. The Lorenz system demonstrates the quality of the error estimation. The discretized bistable examples provide large sparse systems, and our precise error estimation shows, contrary to standard error estimates, that reliable computation is possible for large times.
CDM: AN APPROACH TO LEARNING IN TEXT CATEGORIZATION
Authors: GOLDBERG JEFFREY L. 
Published: September 2004

The Category Discrimination Method (CDM) is a new machine learning algo rithm designed specifically for text categorization. The motivation is there are sta tistical problems associated with natural language text when it is applied as input to existing machine learning algorithms (too much noise, too many features, skewed distribution). The bases of the CDM are research results about the way that humans learn categories and concepts vis-à-vis contrasting concepts. The essential formula is cue validity borrowed from cognitive psychology, and used to select from all possible single word-based features the best predictors of a, given category. The, hypothesis that CDM’s performance. will exceed two non-domain specific al gorithms, Bayesian classification and decision tree learners, is empirically tested.
GROWTH INTENTIONS AND ACTUAL GROWTH: THE IMPACT OF ENTREPRENEURIAL CHOICE
Authors: KOLVEREID LARS , BULLVAG ERLEND 
Published: September 2004

Acknowledgements: We would like to thank the Norwegian Royal Ministry of Industry and the Bodø Graduate School of Business for the financial support that made this research possible. We would also like to thank the Society of Associated Researchers in Entrepreneurship under whose auspices the data for this study was collected. An earlier version of this paper was presented at the 3rd Annual Global Entrepreneurship Conference, Lyon, France, March 1993. The present research investigated: (1) the relationship between entrepreneurs’ growth intentions and actual firm growth, (2) the stability of growth intentions, and (3) the relationship between changes in intentions and actual firm growth. Using a longitudinal design, data were collected from Norwegian entrepreneurs for 1990 and 1992. The results indicate that growth intentions may be used to predict actual growth, that past intentions are related to later intentions, and that changes in growth intentions are associated with changes in growth patterns.
PUBLIC POLICY AND ENTREPRENEURSHIP DEVELOPMENT - SINGAPORE STYLE
Authors: GOH MARK , CHEW IRENE 
Published: September 2004

In the recent attempt to add an external wing to its economy, Singapore has been using its various agencies and instruments to promote the growth of micro enterprises and other types of Small and Medium-sized Enterprises (SMEs). Recognising the potential contribution by entrepreneurs to help sustain economic growth for the country, the Singapore government is now embarking on a proactive public policy to motivate new business entrepreneurship. This paper shows how the government has worked with industry to encourage entrepreneurship development. Particular attention is paid to the activities of various government agencies in relation to new business entrepreneurship and to the barriers of this activity in Singapore. The Singapore experience and programme offer useful insights for policy development and management by other countries in the region.
CRISIS IN MEXICO: ITS EFFECTS ON FAMILY OWNED BUSINESSES
Authors: GRABINSKY SALO 
Published: September 2004

In December 1994, Mexico suffered a deep financial crisis which caused a sustantial devaluation of the peso. The new government as well as millions of entrepreneurs were caught by surprise. This paper will review: 1. An austerity measures, changes in attitude, adaptability and other adjustments forced by this crisis on several representative Mexican family businesses. 2. Conflicts within family members owning to financial, succession and psychological factors. 3. Evolving corporate and family strategies being used by several businesses for survival. 4. Effects of this situation on women entrepreneurs, both in their businesses and in relation to their families. The author will focus on several financial strategies, boards of directors and advisors of family businesses and their effectiveness in conflict resolution and strategic planning. This paper is based on author’s exprience with several dozen firms in Mexico, before and during this still ongoing crisis. Changes in attitudes, family dynamics and management strategies forced by this unexpected “meltdown” will help viable companies survive and grow in the next generation. Moreover, it could mean an important starting point for entrepreneurs and their families everywhere who wish to embark in new ventures in these turbulent times.
USING PRIORITIES TO COMBINE KNOWLEDGE BASES
Authors: PRADHAN SHEKHAR , MINKER JACK 
Published: September 2004

Two or more companies, each with its own knowledge base, may merge. In that case one option is to merge the knowledge bases into one knowledge base. It can happen that some of the information contained in one or more knowledge bases may be in conflict with information in the other knowledge bases. There may be several such points of conflict and any information may be involved in several different such points of conflict. In that case, the integrator of the knowledge bases may prefer a certain claim to another in one conflict-point without necessarily preferring that claim in another conflict-point. Our work constructs a framework within which the consequences of a set of such preferences (expressed as priorities among sets of statements) can be computed. We give three types of semantics for priorities, two of which are shown to be equivalent to one another. The third type of semantics for priorities is shown to be more cautious than the other two. In terms of these semantics for priorities, we give a function for combining knowledge from different sources such that the combined knowledge is conflict-free and satisfies all the priorities.