Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Learn the basic properties and designs of modern VLSI devices, as well as the factors affecting performance, with this thoroughly updated second edition. The first edition has been widely adopted as a standard textbook in microelectronics in many major US universities and worldwide. The internationally-renowned authors highlight the intricate interdependencies and subtle tradeoffs between various practically important device parameters, and also provide an in-depth discussion of device scaling and scaling limits of CMOS and bipolar devices. Equations and parameters provided are checked continuously against the reality of silicon data, making the book equally useful in practical transistor design and in the classroom. Every chapter has been updated to include the latest developments, such as MOSFET scale length theory, high-field transport model, and SiGe-base bipolar devices.

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Fundamentals of Modern VLSI Devices

A prevalent and pervasive view of designing is that it can be modeled using variables and decisions made about what values should be taken by these variables. The activity of designing is carried out with the expectation that the designed artifact will operate in the natural world and the social world. These worlds impose constraints on the variables and their values; so, design could be described as a goal-oriented, constrained, decision- making activity. However, design distinguish- es itself from other similarly described activities not only by its domain but also by additional necessary features. Designing involves exploration, exploring what variables might be appropriate. The process of explo- ration involves both goal variables and deci- sion variables. In addition, designing involves learning: Part of the exploration activity is learning about emerging features as a design proceeds. Finally, design activity occurs within two contexts: the context within which the designer operates and the context produced by the developing design itself. The designer’s perception of what the context is affects the implication of the context on the design. The context shifts as the designer’s perceptions change. Design activity can be now characterized as a goal-oriented, con- strained, decision-making, exploration, and learning activity that operates within a con- text that depends on the designer’s percep- tion of the context.

Design Prototypes: A Knowledge Representation Schema for Design

Creativity: Flow and the Psychology of Discovery and Invention

Cognitive engineering

Statistical analysis is gradually entering all areas of society, be in academia or in the private sector. Statistical software is used by statisticians but also by non-experts (medical doctors, psychologists...). Unfortunately, this kind of software is integrated into obsolete interfaces that completely ignore the principles of HCI and are poorly adapted to non-expert users.

R++, User-Friendly Statistical Software

Process simulation are performed in order to simulate the full fabrication process of an alternative nano-flash memory in order to optimise it and to improve the understanding of the dot storage formation. The influence of various parameters (oxidation temperature, nanowire shape) have been investigated.

Optimisation and Simulation of an Alternative nano-flash Memory: the SASEM device

Hormis pour les jeux video, l’utilisation d’environnement virtuel 3D (EV 3D) sur Smartphone n’est pas encore democratisee. Ceci est du au manque de techniques d’interaction proposees pour in- teragir avec un EV 3D compose de nombreux objets. Dans cet article, nous nous interessons a la selection d’objets dans des EV 3D denses. Nous proposons DichotoZoomqui permet la selection d’objets parmi un ensemble d’objets deja preselectionnes, en un nombre d’actions limite. Dans une premiere etude, nous comparons notre technique a la technique Circulation, proposee par la littera- ture. Celle-ci montre l’efficacite de DichotoZoomlorsque l’ensemble presente un nombre d’elements important. Enfin, nous avons etudie son usage avec differentes modalites d’interaction utilisables sur Smartphone : utilisation de boutons physiques ou sous forme de composants graphiques, interactions gestuelles au moyen de l’ecran tactile ou du Smartphone lui-meme.

DichotoZoom : Technique de sélection d'objets dans un environnement virtuel 3D affiché sur Smartphone

Recent advances in multi-display environments (MDE) has led researchers to develop separated interaction techniques for separated MDE tasks. However, these techniques were not adapted to realistic usage situations. Additionally, when the use of a pen tablet is required, to annotate a document for example, its use in combination with the standard keyboard and mouse often results in homing time cost. In this paper we explore a bimanual approach to support major MDE tasks: it is based on the combination of a multi-degree of freedom device and a pen. Moreover, we explain our approach and current implementation. Finally, we discuss our future work and envisioned studies to evaluate the usability of such an approach.

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A pen-based bimanual approach for interaction in multi-display environments

Systems combining the real and the virtual are becoming more and more prevalent. The Augmented Reality (AR) paradigm illustrates this trend. In comparison with traditional interactive systems, such AR systems involve real entities and virtual ones. And the duality of the two types of entities involved in the interaction has to be studied during the design. We therefore present the ASUR notation: The ASUR description of a system adopts a task-centered point of view and highlights the links between the real world and the virtual world. Based on the characteristics of the ASUR components and relations, predictive usability analysis can be performed by considering the ergonomic property of consistency. We illustrate this analysis on the redesign of a computer assisted surgical application, CASPER.

Emmanuel Dubois

Papers

R++, User-Friendly Statistical Software

Optimisation and Simulation of an Alternative nano-flash Memory: the SASEM device

DichotoZoom : Technique de sélection d'objets dans un environnement virtuel 3D affiché sur Smartphone

A pen-based bimanual approach for interaction in multi-display environments

Consistency in Augmented Reality systems. Discussion