Preface: Volume 68, Number 3

Modern information systems rely more and more on combining concurrent, distributed, mobile and heterogenous components. This move from old systems, typically conceived in isolation, induces the need for new languages and software architectures. In particular, coordination languages have been proposed to cleanly separate computational aspects and communication. On the other hand, software architects face the problem of specifying and reasoning about non-functional requirements. All these issues are widely perceived as fundamental to improve software productivity, to enhance maintainability, to advocate modularity, to promote reusability, and to lead to systems more tractable and more amenable to verification and global analysis.The FOCLASA workshop was organized on August 24th 2002 as a satellite event of Concur'02 with the aim of bringing together researchers working on the foundations of component-based computing, coordination, and software architectures.This volume contains selected 12 papers presented at the workshop. They were reviewed by the program committee, consisting, besides the editors, of

• Rocco De Nicola (University of Firenze, Italy)

• Jos Luiz Fiadeiro (ATX Software and University of Lisbon, Portugal)

• Roberto Gorrieri (University of Bologna, Italy)

• Paola Inverardi (University L'Aquila, Italy)

• Joost Kok (University of Leiden, The Netherlands)

• Antonio Porto (New University of Lisbon, Portugal)

We would like to thank them together with the authors of the papers for their contribution to the meeting. We would also like to thank Michael Mislove for his help in editing this volume. Finally, we are grateful to L. Brim, M. Kretinsky, and A. Kucera for their help in organizing the workshop in Brno.     

On extended P4-reducible and extended P4-sparse graphs

A graph G was defined in [16] as P₄-reducible, if no vertex in G belongs to more than one chordless path on four vertices or P₄. A graph G is defined in [15] as P₄-sparse if no set of five vertices induces more than one P₄, in G. P₄-sparse graphs generalize both P₄-reducible and the well known class of p₄-free graphs or cographs. In an extended abstract in [11] the first author introduced a method using the modular decomposition tree of a graph as the framework for the resolution of algorithmic problems. This method was applied to the study of P₄-sparse and extended P₄-sparse graphs.

In this paper, we begin by presenting the complete information about the method used in [11]. We propose a unique tree representation of P₄-sparse and a unique tree representation of P₄-reducible graphs leading to a simple linear recognition algorithm for both classes of graphs. In this way we simplify and unify the solutions for these problems, presented in [16–19]. The tree representation of an n-vertex P₄-sparse or a P₄-reducible graph is the key for obtaining O(n) time algorithms for the weighted version of classical optimization problems solved in [20]. These problems are NP-complete on general graphs.

Finally, by relaxing the restriction concerning the exclusion of the C₅ cycles from P₄-sparse and P₄-reducible graphs, we introduce the class of the extended P4-sparse and the class of the extendedP₄-reducible graphs. We then show that a minimal amount of additional work suffices for extending most of our algorithms to these new classes of graphs.     

Power MOSFET quality and robustness enhancement with a new QBD characterization performed at probe–die–wafer level

The quality of the gate oxide is a central parameter for power MOSFET devices dedicated to automotive applications. Reliability is systematically evaluated through electrical tests. The purpose of this study is to apply the Q_BD test directly at probe–die–wafer level and to correlate its results with reliability test conclusions. In other words, this new kind of Q_BD test is a monitor of power MOSFET robustness which helps identify extrinsic failures and the process steps responsible. In summary, it is an accurate and fast measurement method of identifying weakened parts and enhancing device quality.     

Evaluation of the quality of collaboration between the client and the therapist in phobia treatments

A growing number of empirical studies evaluate the influence of Mental Health (MH) technology on the clinical effectiveness, the therapeutic relationship (i.e., therapeutic alliance), and usability issues. However, to the authors’ knowledge, no studies have yet been performed regarding the influence of technology on the therapeutic process in terms of collaboration. This study evaluates the quality of collaboration between the client and therapist in Augmented Reality Exposure Therapy (ARET) context and the traditional, In Vivo Exposure Therapy (IVET) context with the Therapeutic Collaborative Scale (TCS). Twenty participants received an intensive session of cognitive behavioral therapy in either a technology-mediated therapeutic context or in a traditional therapeutic context. The results indicate that both therapeutic conditions show high collaboration scores. However, the asymmetry of roles between the therapist and the client under both conditions were detected. Also, a greater level of distraction was observed for therapists in ARET, which affected the quality of the therapists’ involvement in the therapeutic session. The implications of these results are discussed.     

Analysis of muscle length effect on an S type motor-unit fractional multi-model

Muscle models are useful in bio-inspired robotic, because they allow to reproduce accurately natural motion. When they are used for robotic issue, they need to be compact and embeddable. The non-integer model order has the advantage to ensure a parametrical parsimony that permits to implant it easily on an embedded system. Thus, a fractional multi-model of muscle was identified and presented in later paper. This model is able to predict the response of a motor unit to an electrical stimulation, considering isometric contractions (that is to say, muscle length is constant). There are three different physiological types of motor unit (FR, FF, and S). The aim of this work is to study muscle length impact on the multi-model and the limitations of the linear multi-model. Previous paper was published using FR type motor unit. In this paper, the results of the study using S type motor unit are presented.     

Friction and solid-solid adhesion on complex metallic alloys

The discovery in 1987 of stable quasicrystals in the Al–Cu–Fe system was soon exploited to patent specific coatings that showed reduced friction in ambient air against hard antagonists. Henceforth, it was possible to develop a number of applications, potential or commercially exploited to date, that will be alluded to in this topical review. A deeper understanding of the characteristics of complex metallic alloys (CMAs) may explain why material made of metals like Al, Cu and Fe offers reduced friction; low solid–solid adhesion came later. It is linked to the surface energy being significantly lower on those materials, in which translational symmetry has become a weak property, that is determined by the depth of the pseudo-gap at the Fermi energy. As a result, friction is anisotropic in CMAs that builds up according to the translation symmetry along one direction, but is aperiodic along the other two directions. A review is given in this article of the most salient data found along these lines during the past two decades or so.     

Arylene bisimides with triarylamine N-substituents as new solution processable organic semiconductors: Synthesis,spectroscopic, electrochemical and electronic properties

New solution processable organic semiconductors, consisting of pyrromelitic, naphthalene or perylene bisimide core and triarylamine N-substituents, have been synthesized. All three compounds are electrochemically active and undergo quasi-reversible oxidation and reduction as evidenced by cyclic voltammetry investigations. The oxidation process involves the transformation of the triarylamine substituents into radical cations as proven spectroscopically and spectroelectrochemically. The reduction process occurs at the arylene bisimide core leading to the formation of a radical anion and eventually a dianion in the second step. These findings are in perfect agreement with the DFT calculations which show that in the synthesized molecules the HOMO orbital is located on the triarylamine moiety whereas the LUMO one on the bisimide core. In all molecules studied the electrochemically determined ionization potential (IP) is slightly higher than 5.0 eV whereas in naphthalene and perylene derivatives the electron affinity (EA) is close to ?3.9 eV. These values fulfill the requirements for n-type (electron) semiconductors in air operating n-channel field effect transistors (FETs) as well as for p-type (hole) conductors in p-channel FETs. To verify whether the newly synthesized compounds exhibit the expected electrical transport properties all organic (CYTOP dielectric) test transistors were fabricated. All three semiconductors showed no field effect in the n-channel configuration. To the contrary, they could be used in p-channel FETs showing, in the saturation regime, the hole mobility approaching 10^?4 cm² V^?1 s^?1 – the value which slightly exceeds that measured for low molecular weight, amorphous triarylamine semiconductors.     

Technique for delaying splashing in jet wiping process

The current study presents an experimental investigation of a technique for delaying the occurrence of splashing in jet wiping process by means of a side jet. Gas jet wiping is a hydrodynamic method of controlling the film thickness applied on a substrate in coating processes. It consists of a turbulent slot jet impinging on a moving surface coated with a liquid film. The process is limited by splashing; a rather violent film instability which is characterized by the ejection of droplets from the runback flow and results in the detachment of the film from the substrate. In the present study an additional side jet is used close to the main wiping jet in order to stabilize the runback flow and avoid splashing. The mean film thickness after wiping is measured using a light absorption method and the results are compared for the single jet wiping and two jet configuration. It is shown that the use of the side jet allows for stronger wiping, resulting in lower values of the final film thickness which cannot be achieved with a single jet.