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

In this paper, we propose a collaborative design method combining the informal power of creative session and the formal generative power of a mixed interaction model called MACS (Model Assisted Creativity Session). By using a formal notation during creative sessions, interdisciplinary teams systematically explore combinations between the physical and digital spaces and remain focused on the design problem to address. In this paper, we introduce the MACS method principles and illustrate its application on two case studies.

MACS: combination of a formal mixed interaction model with an informal creative session

This paper presents an architecture to support fast prototyping of augmented reality systems, based on virtual reality. The architecture defines simulation services separated from other aspects of the system. These services support incremental evolution of simulated prototypes into nonsimulated systems. Focus is also placed on user interaction,through the definition of an interaction architecture that uniformly handles both input and tracking. Both architectures are component-oriented, favoring white-box reuse.

Virtual Reality Simulation for Prototyping Augmented Reality

Recent technological advances in immersive devices open up many opportunities for users to visualize data in their environments. However, current interactive solutions fail at providing a convenient approach to manipulate such complex immersive visualizations. In this article, we present a new approach to interact in these environments, that we call On-Body Tangible interaction (OBT): using the body to physically support the manipulation of an input device. The use of the body to support the interaction allows the user to move in his environment and avoid the inherent fatigue of mid-air interactions. In this paper, we explore the use of a rolling device, which fits well on-body interaction thanks to its form factor and offers enough degrees of freedom (DoF) for data manipulation. We first propose a new design space for OBT interactions, and specifically on the forearm. Then we validate the feasibility of such an approach through an experiment aimed at establishing the range, stability and comfort of gestures performed with the device on the forearm. Our results reveal that on-body tangible interaction on the forearm is stable and offers multiple DoFs with little fatigue. We illustrate the benefits of our approach through sample applications where OBT interactions are used to select and execute space-time cube operations.

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On-Body Tangible Interaction: Using the Body to Support Tangible Manipulations for Immersive Environments

This paper describes a multidisciplinary approach to the modelling of the mixed reality systems domain. Such modelling, useful for structuring such a recent interaction domain, and to facilitate design and evaluation from both software engineering and ergonomics perspectives, is based on the combination of two approaches: the ASUR notation and an ergonomic recommendations-based model. Both approaches are presented as well as the results of their combination. The resulting model, an extension of the ASUR notation, is described as well as its limits and perspectives.

Un modèle préliminaire du domaine des systèmes mixtes

New forms of interactive systems, hereafter referred to as Mixed Interactive Systems (MIS), are based on the use of physical artefacts present in the environment. Mixing the digital and physical worlds affects the development of interactive systems, especially from the point of view of the design resources which need to express new dimensions. Consequently, there is a crucial need to clearly describe the content and utility of the recent models associated to these new interaction forms. Based on existing initiatives in the field of HCI, this chapter first highlights the interest of using a Model-Driven Engineering (MDE) approach for the design of MIS. Then, this chapter retraces the application of a MDE approach on a specific Mixed Interaction design resource. The resulted contribution is a motivated, explicit, complete and standardized definition of the ASUR model, a model for mixed interaction design. This definition constitutes a basis to promote the use of this model, to support its diffusion and to derive design tools from this model. The model-driven development of a flexible ASUR editor is finally introduced, thus facilitating the insertion of model extensions and articulations.

Emmanuel Dubois

Papers

MACS: combination of a formal mixed interaction model with an informal creative session

Virtual Reality Simulation for Prototyping Augmented Reality

On-Body Tangible Interaction: Using the Body to Support Tangible Manipulations for Immersive Environments

Un modèle préliminaire du domaine des systèmes mixtes

Taking Advantage of Model-Driven Engineering Foundations for Mixed Interaction Design