Expressing Priorities and External Probabilities in Process Algebra via Mixed Open/Closed Systems

Defining operational semantics for a process algebra is often based either on labeled transition systems that account for interaction with a context or on the so-called reduction semantics: we assume to have a representation of the whole system and we compute unlabeled reduction transitions (leading to a distribution over states in the probabilistic case). In this paper we consider mixed models with states where the system is still open (towards interaction with a context) and states where the system is already closed. The idea is that (open) parts of a system “P” can be closed via an operator “P↑G” that turns already synchronized actions whose “handle” is specified inside “G” into prioritized reduction transitions (and, therefore, states performing them into closed states). We show that we can use the operator “P↑G” to express multi-level priorities and external probabilistic choices (by assigning weights to handles inside G), and that, by considering reduction transitions as the only unobservable τ transitions, the proposed technique is compatible, for process algebra with general recursion, with both standard (probabilistic) observational congruence and a notion of equivalence which aggregates reduction transitions in a (much more aggregating) trace based manner. We also observe that the trace-based aggregated transition system can be obtained directly in operational semantics and we present the “aggregating” semantics. Finally, we discuss how the open/closed approach can be used to also express discrete and continuous (exponential probabilistic) time and we show that, in such timed contexts, the trace-based equivalence can aggregate more with respect to traditional lumping based equivalences over Markov Chains.     

Control design for recycled, multi unit processes

An integrated multi-unit chemical plant presents a challenging control design problem due to the existence of recycling streams. In this paper, we develop a framework for analyzing the effects of recycling dynamics on closed-loop performance from which a systematic design of a decentralized control system for a recycled, multi-unit plant is established. In the proposed approach, the recycled streams are treated as unmodelled dynamics of the “unit” model so that their effects on closed-loop stability and performance can be analyzed using the robust control theory. As a result, two measures are produced: (1) the ν-gap metric, which quantifies the strength of recycling effects, and (2) the maximum stability margin of “unit” controller, which represents the ability of the “unit” controller to compensate for such effects. A simple rule for the “unit” control design is then established using the combined two measures in order to guarantee the attainment of good overall closed-loop performances. As illustrated by several design examples, the controllability of a recycled, multi unit process under a decentralized “unit” controller can be determined without requiring any detailed design of the “unit” controller because the simple rule is calculated from the open-loop information only.     

Basic Theory of F-Bounded Quantification

System F-bounded is a second-order typed lambda calculus, where the basic features of object-oriented languages can be naturally modelled. F-bounded extends the better known system F, in a way that provides an immediate solution for the treatment of the so-called “binary methods.” Although more powerful than F and also quite natural, system F-bounded has only been superficially studied from a foundational perspective and many of its essential properties have been conjectured but never proved in the literature. The aim of this paper is to give a solid foundation to F-bounded, by addressing and proving the key properties of the system. In particular, transitivity elimination, completeness of the type checking semi-algorithm, the subject reduction property for βη reduction, conservativity with respect to system F, and antisymmetry of a “full” subsystem are considered, and various possible formulations for system F-bounded are compared. Finally, a semantic interpretation of system F-bounded is presented, based on partial equivalence relations.     

Dynamic learning from multiple examples for semantic object segmentation and search

We present a novel “dynamic learning” approach for an intelligent image database system to automatically improve object segmentation and labeling without user intervention, as new examples become available, for object-based indexing. The proposed approach is an extension of our earlier work on “learning by example,” which addressed labeling of similar objects in a set of database images based on a single example. The proposed dynamic learning procedure utilizes multiple example object templates to improve the accuracy of existing object segmentations and labels. Multiple example templates may be images of the same object from different viewing angles, or images of related objects. This paper also introduces a new shape similarity metric called normalized area of symmetric differences (NASD), which has desired properties for use in the proposed “dynamic learning” scheme, and is more robust against boundary noise that results from automatic image segmentation. Performance of the dynamic learning procedures has been demonstrated by experimental results.     

Extracting a polyhedron from a single-view sketch: Topological construction of a wireframe sketch with minimal hidden elements

An essential prerequisite to construct a manifold trihedral polyhedron from a given natural (or partial-view) sketch is solution of the “wireframe sketch from a single natural sketch (WSS)” problem, which is the subject of this paper. Published solutions view WSS as an “image-processing”/“computer vision” problem where emphasis is placed on analyzing the given input (natural sketch) using various heuristics. This paper proposes a new WSS method based on robust tools from graph theory, solid modeling and Euclidean geometry. Focus is placed on producing a minimal wireframe sketch that corresponds to a topologically correct polyhedron.     

Dimension elevation formula for Chebyshevian blossoms

A given polynomial of degree less than or equal to n naturally “blossoms” into a function of n variables called its blossom. Considered as a polynomial function of degree less than or equal to (n+1) it “blossoms” into a “new” blossom which is now a function of (n+1) variables. A classical formula expresses any value of this new blossom as a strictly convex combination of (n+1) values of the initial one. We establish a similar formula for Chebyshevian blossoms.     

A Duality in Proof Systems for Recursive Type Equality and for Bisimulation Equivalence on Cyclic Term Graphs

This paper is concerned with a proof-theoretic observation about two kinds of proof systems for regular cyclic objects. It is presented for the case of two formal systems that are complete with respect to the notion of “recursive type equality” on a restricted class of recursive types in μ-term notation. Here we show the existence of an immediate duality with a geometrical visualization between proofs in a variant of the coinductive axiom system due to Brandt and Henglein and “consistency-unfoldings” in a variant of a 'syntactic-matching' proof system for testing equations between recursive types due to Ariola and Klop.Finally we sketch an analogous result of a duality between a similar pair of proof systems for bisimulation equivalence on equational specifications of cyclic term graphs.     

Overcoming Heterogeneity and Autonomy in Multidatabase Systems

A multidatabase system (MDBS) is a software system for integration of preexisting and independent local database management systems (DBMSs). The transaction management problem in MDBSs consists of designing appropriate software, on top of local DBMSs, such that users can execute transactions that span multiple local DBMSs without jeopardizing database consistency. The difficulty in transaction management in MDBSs arises due to the heterogeneity of the transaction management algorithms used by the local DBMSs, and the desire to preserve their local autonomy. In this paper, we develop a framework for designing fault-tolerant transaction management algorithms for MDBS environments that effectively overcomes the heterogeneity- and autonomy-induced problems. The developed framework builds on our previous work. It uses the approach described in S. Mehrotra et al. (1992, in “Proceedings of ACM–SIGMOD 1992 International Conference on Management of Data, San Diego, CA”) to overcome the problems in ensuring serializability that arise due to heterogeneity of the local concurrency control protocols. Furthermore, it uses a redo approach to recovery for ensuring transaction atomicity (Y. Breitbart et al., 1990, in “Proceedings of ACM–SIGMOD 1990 International Conference on Management of Data, Atlantic City, NJ;” Mehrotra et al., 1992, in “Proceedings of the Eleventh ACM SIGACT–SIGMOD–SIGART Symposium on Principles of Database Systems, San Diego, CA;” and A. Wolski and J. Veijalainen, 1990, in “Proceedings of the International Conference on Databases, Parallel Architectures and Their Applications”, pp. 321–330), that strives to ensure atomicity of transactions without the usage of the 2PC protocol. We reduce the task of ensuring serializability in MDBSs in the presence of failures to solving three independent subproblems, solutions to which together constitute a complete strategy for failure-resilient transaction management in MDBS environments. We develop mechanisms with which each of the three subproblems can be solved without requiring any changes be made to the preexisting software of the local DBMSs and without compromising their autonomy.     

A View on Decoherence Via Master Equations

This paper addresses the discussion on probabilistic features of the concept of decoherence as it appeared in quantum physics. Given a Lindblad-type generator of an open system dynamics, we derive applicable criteria to characterize decoherent behaviour.Presented at the International Conference “Entanglement, Information & Noise”, Krzyżowa, Poland, June 14-20, 2004.Partially supported by FONDECYT grant 1030552.     

Investigation of engine fault diagnosis using discrete wavelet transform and neural network

An investigation of a fault diagnostic technique for internal combustion engines using discrete wavelet transform (DWT) and neural network is presented in this paper. Generally, sound emission signal serves as a promising alternative to the condition monitoring and fault diagnosis in rotating machinery when the vibration signal is not available. Most of the conventional fault diagnosis techniques using sound emission and vibration signals are based on analyzing the signal amplitude in the time or frequency domain. Meanwhile, the continuous wavelet transform (CWT) technique was developed for obtaining both time-domain and frequency-domain information. Unfortunately, the CWT technique is often operated over a longer computing time. In the present study, a DWT technique which is combined with a feature selection of energy spectrum and fault classification using neural network for analyzing fault signal is proposed for improving the shortcomings without losing its original property. The features of the sound emission signal at different resolution levels are extracted by multi-resolution analysis and Parseval’s theorem [Gaing, Z. L. (2004). Wavelet-based neural network for power disturbance recognition and classification. IEEE Transactions on Power Delivery 19, 1560–1568]. The algorithm is obtained from previous work by Daubechies [Daubechies, I. (1988). Orthonormal bases of compactly supported wavelets. Communication on Pure and Applied Mathematics 41, 909–996.], the“db4”, “db8” and “db20” wavelet functions are adopted to perform the proposed DWT technique. Then, these features are used for fault recognition using a neural network. The experimental results indicated that the proposed system using the sound emission signal is effective and can be used for fault diagnosis of various engine operating conditions.     

Internal stabilizability of the Navier–Stokes equations

One shows that the steady-state solutions to Navier–Stokes equations in d-dimensional domains Ω, d=2,3 with Dirichlet and slip curl boundary conditions are exponentially stabilizable by proportional controllers with the support in open subsets ωΩ such that Ωω is sufficiently “small”.     

Preprocessing of Intractable Problems

Some computationally hard problems, e.g., deduction in logical knowledge bases– are such that part of an instance is known well before the rest of it, and remains the same for several subsequent instances of the problem. In these cases, it is useful to preprocess off-line this known part so as to simplify the remaining on-line problem. In this paper we investigate such a technique in the context of intractable, i.e., NP-hard, problems. Recent results in the literature show that not all NP-hard problems behave in the same way: for some of them preprocessing yields polynomial-time on-line simplified problems (we call them compilable), while for other ones their compilability implies some consequences that are considered unlikely. Our primary goal is to provide a sound methodology that can be used to either prove or disprove that a problem is compilable. To this end, we define new models of computation, complexity classes, and reductions. We find complete problems for such classes, “completeness” meaning they are “the less likely to be compilable.” We also investigate preprocessing that does not yield polynomial-time on-line algorithms, but generically “decreases” complexity. This leads us to define “hierarchies of compilability,” that are the analog of the polynomial hierarchy. A detailed comparison of our framework to the idea of “parameterized tractability” shows the differences between the two approaches.     

‘Because it’s boring, irrelevant and I don’t like computers’: Why high school girls avoid professionally-oriented ICT subjects

The current paper details results from the Girls and ICT survey phase of a three year study investigating factors associated with low participation rates by females in education pathways leading to professional level information and communications technology (ICT) professions. The study is funded through the Australian Research Council’s (ARC) Linkage Grants Scheme. It involves a research partnership between Education Queensland (EQ), industry partner Technology One and academic researchers at (affiliation removed for review purposes). Respondents to the survey were 1453 senior high school girls. Comparisons were drawn between Takers (n = 131) and Non Takers (n = 1322) of advanced level computing subjects. Significant differences between the groups were found on four questions: “The subjects are interesting”; “I am very interested in computers”; “The subject will be helpful to me in my chosen career path after school”; and “It suited my timetable”. The research has demonstrated that senior high school girls tend to perceive advanced computing subjects as boring and they express a strong aversion to computers.     

A simple algorithm for the unique characterization of convex polygons

A simple method for specifying the shape and orientation of a convex polygon is described. The method utilizes eigenvalues and eigenvectors of a “moment of inertia” or mass matrix computed from the nodal coordinates of the polygon. The “shape” is characterized then by the parameter ( , where ξ₁ and ξ₂ are the eigenvalues (ξ₁ ξ₂), and the orientation by the axial direction of the first eigenvector. FORTRAN subroutines are provided for this algorithm.     

On the controllability of linear juggling mechanical systems

This paper deals with the controllability of a class of nonsmooth complementarity mechanical systems. Due to their particular structure they can be decomposed into an “object” and a “robot”, consequently they are named juggling systems. It is shown that the accessibility of the “object” can be characterized by nonlinear constrained equations, or generalized equations. Examples are presented, including a simple model of backlash. The main focus of the work is about linear jugglers.     

Multidimensional visualisation for process historical data analysis: a comparative study with multivariate statistical process control

This paper describes a comparative study of a multidimensional visualisation technique and multivariate statistical process control (MSPC) for process historical data analysis. The visualisation technique uses parallel coordinates which visualise multidimensional data using two dimensional presentations and allow identification of clusters and outliers, therefore, can be used to detect abnormal events. The study is based on a database covering 527 days of operation of an industrial wastewater treatment plant. It was found that both the visualisation technique and MSPC based on T² chart captured the same 17 days as “clearly abnormal” and another eight days as “likely abnormal”. Pattern recognition using K-means clustering was also applied to the same data in literature and was found to have identified 14 out of the 17 “clearly abnormal” days.     

An Effective Coalgebraic Bisimulation Proof Method

The bisimulation “up-to-…” technique provides an effective way to relieve the amount of work in proving bisimilarity of two processes. This paper develops a fresh and direct approach to generalize this set-theoretic “up-to-...” principle to the setting of coalgebra theory. The notion of consistent function is introduced, as a generalization of Sangiorgi's sound function. Then, in order to prove that there are only bisimilar pairs in a relation, it is sufficient to find a morphism from it to the “lifting” of its image under some consistent function. One example is given showing that every self-bisimulation in normed BPA is just such a relation. What's more, we investigate the connection between span-bisimulation and ref-bisimulation. As a result, λ-bisimulation turns out to be covered by our new principle.     

It's more than just use: An exploration of telemedicine use quality

“Simply saying that more use will yield more benefits without considering the nature of this use (and context) is clearly insufficient” [W.H. DeLone, E.R. McLean, The DeLone and McLean model of information system success: a ten-year update, Journal of Management Information Systems 19 (4) (2003) 9–30, p. 16]. Our research specifies the use quality construct in the context of a mission critical system deployment—namely, the use of medical video conferencing for patient exams. The product of this field study is a socio-technical framework for use quality in telemedicine service encounters. We also propose generalized categories (which may extend across domains) for identified attributes, provide a comparative overview of patient and provider perspectives, and discuss the effects of and remedies for selected attribute deficiencies.     

Variable structure exponential stabilization of chained systems based on the extended nonholonomic integrator

In this paper, a new variable structure control strategy for exponentially stabilizing chained systems is presented based on the extended nonholonomic integrator model, the discontinuous coordinate transformation and the “reaching law method” in variable structure control design. The proposed approach converts the stabilization problem of an n-dimensional chained system into the pole-assignment problem of an (n−3)-dimensional linear time-invariant system and consequently simplifies the stabilization controller design of nonholonomic chained systems.     

Completeness of Continuation Models for λμ-Calculus

We show that a certain simple call-by-name continuation semantics of Parigot's λ_μ-calculus is complete. More precisely, for every λ_μ-theory we construct a cartesian closed category such that the ensuing continuation-style interpretation of λ_μ, which maps terms to functions sending abstract continuations to responses, is full and faithful. Thus, any λ_μ-category in the sense of L. Ong (1996, in “Proceedings of LICS '96,” IEEE Press, New York) is isomorphic to a continuation model (Y. Lafont, B. Reus, and T. Streicher, “Continuous Semantics or Expressing Implication by Negation,” Technical Report 93-21, University of Munich) derived from a cartesian-closed category of continuations. We also extend this result to a later call-by-value version of λ_μ developed by C.-H. L. Ong and C. A. Stewart (1997, in “Proceedings of ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, Paris, January 1997,” Assoc. Comput. Mach. Press, New York).