An earlier time for inserting and/or accelerating tasks

In a periodic real-time system scheduled by the EDF (Earliest Deadline First) algorithm (Liu and Layland, J. ACM 20(1), 40–61, 1973; Barauh, Proc. of the 27th IEEE International Real-Time Systems Symposium, 379–387, 2006; Buttazzo, J. Real-Time Syst. 29(1), 5–26, 2005), when new tasks have to be inserted into the system at run-time and/or current tasks request to increase their rates in response to internal or external events, the new sum of the utilizations after the insertion and/or acceleration should be limited, otherwise, one or more current tasks should usually be compressed (their periods being prolonged) in order to avoid overload. Buttazzo offered a time from which on this kind of adjustment can be done without causing any deadline miss in the system (Buttazzo et al., IEEE Trans. Comput. 51(3), 289–302, 2002). It is, however, not early enough. In this paper, an earlier time is given and formally proved.

U-multimedia framework: a secure and intelligent multimedia service framework based on context information in U-home

In the last few years, intelligent secured multimedia services play a vital role along with ubiquitous home environment (Park et al. in Lecture Notes in Computer Science, vol. 4097, pp. 660–670, [2006]; Lecture Notes in Computer Science, vol. 4159, pp. 893–901, [2006]; IEICE Trans. Inf. Syst. E89-D(12):2831–2837, [2006]; Lecture Notes in Artificial Intelligence, vol. 4252, pp. 777–784, [2006]; Lecture Notes in Artificial Intelligence, vol. 3801, pp. 313–320, [2005]). There are certain constrains and limitations in providing effective and efficient services in U-home. The mechanism and applications are integrated to realize such services. Three different kinds of ubiquitous multimedia services are proposed in the framework. Based on the temporal and spatial context information, the surrounding situations are recognized. The contexts are collected and well analyzed with the preconditions to provide the final services. The proposed framework provides efficient services in the multimedia based deices based on the current context information.

An Improved LOT Model for Image Restoration

Some second order PDE-based image restoration models such as total variation (TV) minimization or ROF model of Rudin et al. (Physica D 60, 259–268, 1992) can easily give rise to staircase effect, which may produce undesirable blocky image. LOT model proposed by Laysker, Osher and Tai (IEEE Trans. Image Process. 13(10), 1345–1357, 2004) has alleviated the staircase effect successfully, but the algorithms are complicated due to three nonlinear second-order PDEs to be computed, besides, when we have no information about the noise, the model cannot preserve edges or textures well. In this paper, we propose an improved LOT model for image restoration. First, we smooth the angle θ rather than the unit normal vector n, where n=(cos θ,sin θ). Second, we add an edge indicator function in order to preserve fine structures such as edges and textures well. And then the dual formulation of TV-norm and TV _g -norm are used in the numerical algorithms. Finally, some numerical experiments prove our proposed model and algorithms to be effective.

Numerical study on gas–liquid nano-flows with pseudo-particle modeling and soft-particle molecular dynamics simulation

We couple pseudo-particle modeling (PPM, Ge and Li in Chem Eng Sci 58(8):1565–1585, 2003), a variant of hard-particle molecular dynamics, with standard soft-particle molecular dynamics (MD) to study an idealized gas–liquid flow in nano-channels. The coupling helps to keep sharp contrast between gas and liquid behaviors and the simulations conducted provide a reference frame for exploring more complex and realistic gas–liquid nano-flows. The qualitative nature and general flow patterns of the flow under such extreme conditions are found to be consistent with its macro-scale counterpart.

Approximate schemas,source-consistency and query answering

We use the Edit distance with Moves on words and trees and say that two regular (tree) languages are ε-close if every word (tree) of one language is ε-close to the other. A transducer model is introduced to compare tree languages (schemas) with different alphabets and attributes. Using the statistical embedding of Fischer et al. (Proceedings of 21st IEEE Symposium on Logic in Computer Science, pp. 421–430, 2006), we show that Source-Consistency and Approximate Query Answering are testable on words and trees, i.e. can be approximately decided within ε by only looking at a constant fraction of the input.

A message passing strategy for array redistributions in a torus network

The array redistribution problem occurs in many important applications in parallel computing. In this paper, we consider this problem in a torus network. Tori are preferred to other multidimensional networks (like hypercubes) due to their better scalability (IEE Trans. Parallel Distrib. Syst. 50(10), 1201–1218, [2001]). We present a message combining approach that splits any array redistribution problem in a series of broadcasts where all sources send messages of the same size, thus a balanced traffic load is achieved. Unlike existing array redistribution algorithms, the scheme introduced in this work eliminates the need for data reorganization in the memory of the source and target processors. Moreover, the processing of the scheduled broadcasts is pipelined, thus the total cost of redistribution is reduced.

Parallelism of iterative CT reconstruction based on local reconstruction algorithm

An iterative algorithm is suited to reconstruct CT images from noisy or truncated projection data. However, as a disadvantage, the algorithm requires significant computational time. Although a parallel technique can be used to reduce the computational time, a large amount of communication overhead becomes an obstacle to its performance (Li et al. in J. X-Ray Sci. Technol. 13:1–10, 2005). To overcome this problem, we proposed an innovative parallel method based on the local iterative CT reconstruction algorithm (Wang et al. in Scanning 18:582–588, 1996 and IEEE Trans. Med. Imaging 15(5):657–664, 1996). The object to be reconstructed is partitioned into a number of subregions and assigned to different processing elements (PEs). Within each PE, local iterative reconstruction is performed to recover the subregion. Several numerical experiments were conducted on a high performance computing cluster. And the FORBILD head phantom (Lauritsch and Bruder ) was used as benchmark to measure the parallel performance. The experimental results showed that the proposed parallel algorithm significantly reduces the reconstruction time, hence achieving a high speedup and efficiency.

A unifying framework for robot control with redundant DOFs

Recently, Udwadia (Proc. R. Soc. Lond. A 2003:1783–1800, 2003) suggested to derive tracking controllers for mechanical systems with redundant degrees-of-freedom (DOFs) using a generalization of Gauss’ principle of least constraint. This method allows reformulating control problems as a special class of optimal controllers. In this paper, we take this line of reasoning one step further and demonstrate that several well-known and also novel nonlinear robot control laws can be derived from this generic methodology. We show experimental verifications on a Sarcos Master Arm robot for some of the derived controllers. The suggested approach offers a promising unification and simplification of nonlinear control law design for robots obeying rigid body dynamics equations, both with or without external constraints, with over-actuation or underactuation, as well as open-chain and closed-chain kinematics.

A software tool for verification of Spiking Neural P Systems

The formal verification of a Spiking Neural P System (SN P Systems, for short) designed for solving a given problem is usually a hard task. Basically, the verification process consists of the search of invariant formulae such that, once proved their validity, show the right answer to the problem. Even though there does not exist a general methodology for verifying SN P Systems, in (Păun et al., Int J Found Comput Sci 17(4):975–1002, 2006) a new tool based on the transition diagram of the P system has been developed for helping the researcher in the search of invariant formulae. In this paper we show a software tool which allows to generate the transition diagram of an SN P System in an automatic way, so it can be considered as an assistant for the formal verification of such computational devices.

Comparative analysis of simple facial features extractors

In the article a certain class of feature extractors for face recognition is presented. The extraction is based on simple approaches: image scaling with pixel concatenation into a feature vector, selection of a small number of points from the face area, face image’s spectrum, and finally pixel intensities histogram. The experiments performed on several facial image databases (BioID [4], ORL face database [27], FERET [30]) show that face recognition using this class of extractors is particularly efficient and fast, and can have straightforward implementations in software and hardware systems. They can also be used in fast face recognition system involving feature-integration, as well as a tool for similar faces retrieval in 2-tier systems (as initial processing, before exact face recognition).

Invariant Signatures of Closed Planar Curves

We prove that any subset of ℝ² parametrized by a C ¹ periodic function and its derivative is the Euclidean invariant signature of a closed planar curve. This solves a problem posed by Calabi et al. (Int. J. Comput. Vis. 26:107–135, 1998). Based on the proof of this result, we then develop some cautionary examples concerning the application of signature curves for object recognition and symmetry detection as proposed by Calabi et al.

Supporting scenario evolution

Scenarios have been shown to be very helpful in identifying and communicating requirements for computer-based systems (CBSs). However, they appear not to be applicable to the rest of the CBS development process. Making scenarios more useful for the entire software development lifecycle requires integrating scenarios to other representations used during CBS development. This integration is achieved with tracing technology. Having integrated scenarios into the entire software development lifecycle creates the necessity to maintain scenarios through the inevitable changes that they and other documents undergo and to subject them to configuration management. We have prototyped automated support for full-lifecycle scenario management and have applied it to some non-trivial systems.This paper is an amalgamation and extension of the conference papers numbered 8, 9, 10, and 11 in the bibliography of this paper.

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Sensation seeking and e-shoppers

The concept of sensation seeking has been extensively researched. However, a few studies have been carried out on the relationship between sensation seeking and e-commerce. More specifically, it studied the purchase of leisure products, which usually have a higher frequency of purchase on the Internet. With this in mind, the Brief Sensation Seeking Scale (BSSS) created by Hoyle et al. (Pers. Individ. Differ. 32:401–414, 2002) is used, which adapts items from the SSS-V (Zuckerman et al., J. Consult. Clin. Psychol. 46:139–149, 1978). The results, based on a sample of 393 participants, explain that significant differences exist between e-shoppers and non-e-shoppers of leisure products with respect to the subscale of thrill and adventure seeking. Also, it is observed that there are significant differences between shoppers and non-shoppers only with women.

Zero-Automatic Networks

We continue the study of zero-automatic queues first introduced in Dao-Thi and Mairesse (Adv Appl Probab 39(2):429–461, 2007). These queues are characterized by a special buffering mechanism evolving like a random walk on some infinite group or monoid. The simple M/M/1 queue and Gelenbe’s G-queue with positive and negative customers are the two simplest 0-automatic queues. All stable 0-automatic queues have an explicit “multiplicative” stationary distribution and a Poisson departure process (Dao-Thi and Mairesse, Adv Appl Probab 39(2):429–461, 2007). In this paper, we introduce and study networks of 0-automatic queues. We consider two types of networks, with either a Jackson-like or a Kelly-like routing mechanism. In both cases, and under the stability condition, we prove that the stationary distribution of the buffer contents has a “product-form” and can be explicitly determined. Furthermore, the departure process out of the network is Poisson.

Efficient Detection of Patterns in 2D Trajectories of Moving Points

Moving point object data can be analyzed through the discovery of patterns in trajectories. We consider the computational efficiency of detecting four such spatio-temporal patterns, namely flock, leadership, convergence, and encounter, as defined by Laube et al., Finding REMO—detecting relative motion patterns in geospatial lifelines, 201–214, (2004). These patterns are large enough subgroups of the moving point objects that exhibit similar movement in the sense of direction, heading for the same location, and/or proximity. By the use of techniques from computational geometry, including approximation algorithms, we improve the running time bounds of existing algorithms to detect these patterns.

Content-based image retrieval using fuzzy perceptual feedback

In this paper, a new framework called fuzzy relevance feedback in interactive content-based image retrieval (CBIR) systems is introduced. Conventional binary labeling scheme in relevance feedback requires a crisp decision to be made on the relevance of the retrieved images. However, it is inflexible as user interpretation of visual content varies with respect to different information needs and perceptual subjectivity. In addition, users tend to learn from the retrieval results to further refine their information requests. It is, therefore, inadequate to describe the user’s fuzzy perception of image similarity with crisp logic. In view of this, we propose a fuzzy relevance feedback approach which enables the user to make a fuzzy judgement. It integrates the user’s fuzzy interpretation of visual content into the notion of relevance feedback. An efficient learning approach is proposed using a fuzzy radial basis function (FRBF) network. The network is constructed based on the user’s feedbacks. The underlying network parameters are optimized by adopting a gradient-descent training strategy due to its computational efficiency. Experimental results using a database of 10,000 images demonstrate the effectiveness of the proposed method.

Level sets and the representation theorem for intuitionistic fuzzy sets

We discuss the concept of a level set of a fuzzy set and the related ideas of the representation theorem and Zadeh’s extension principle. We then describe the extension of these ideas to the case of interval valued fuzzy sets (IVFS). We then recall the formal equivalence between IVFS and intuitionistic fuzzy sets (IFS). This equivalence allows us to naturally extend the concepts of level sets, representation theorem and extension principle from the domain of IVFS to the domain of IFS. What is important to note here is that in the case of these non-standard fuzzy sets, interval valued and intuitionistic, the number of distinct level sets can be greater then the number of distinct membership grades of the fuzzy set being represented. This is a result of the fact that the distinct level sets are generated by the power set of the membership grades. In particular, the minimum of each subset of membership grades provides a level set. In the case of the standard fuzzy sets the minimum of a subset of membership grades results in one of the elements in the subset. In the case of the non-standard fuzzy sets, the membership grades are not linearly ordered and hence taking the minimum of a subset of these can result in a value that was not one of the members of the subset.

Periodicity and stability issues of a <Emphasis Type="Italic">chaotic</Emphasis> pattern recognition neural network

Traditional pattern recognition (PR) systems work with the model that the object to be recognized is characterized by a set of features, which are treated as the inputs. In this paper, we propose a new model for PR, namely one that involves chaotic neural networks (CNNs). To achieve this, we enhance the basic model proposed by Adachi (Neural Netw 10:83–98, 1997), referred to as Adachi’s Neural Network (AdNN), which though dynamic, is not chaotic. We demonstrate that by decreasing the multiplicity of the eigenvalues of the AdNN’s control system, we can effectively drive the system into chaos. We prove this result here by eigenvalue computations and the evaluation of the Lyapunov exponent. With this premise, we then show that such a Modified AdNN (M-AdNN) has the desirable property that it recognizes various input patterns. The way that this PR is achieved is by the system essentially sympathetically “resonating” with a finite periodicity whenever these samples (or their reasonable resemblances) are presented. In this paper, we analyze the M-AdNN for its periodicity, stability and the length of the transient phase of the retrieval process. The M-AdNN has been tested for Adachi’s dataset and for a real-life PR problem involving numerals. We believe that this research also opens a host of new research avenues. Research partially supported by the Natural Sciences and Engineering Research Council of Canada.

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Perfect Simulation of a Class of Stochastic Hybrid Systems with an Application to Peer to Peer Systems

In this paper we present a class of hybrid systems made of deterministic differential equations and random discrete jumps. We then show how to construct a simulation of such a stochastic hybrid system that provides perfect samples of its asymptotic behavior based on the extension to continuous state-space of coupling-from-the-past techniques introduced by Foss and Tweedie (Stoch Models 14:187–204, 1998) and using suitable envelope trajectories to tackle non-monotonicity. The applicability of the method is illustrated by showing how this framework can be used to model the Squirrel peer to peer system and by reporting a simulation study based on this approach. This paper provides both a framework on how to carry simulation based experimental studies of large and complex hybrid systems and its application in the Squirrel model demonstrating how versatile and powerful this approach can be over a typical example.