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.

/pdf/fundamentals-of-modern-vlsi-devices-471xd7l9pf.pdf

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

Electron microscopy analysis of MOSFET structures

Initially designed for TV broadcasting, DVB standard families have become mature technologies for Internet communications via satellite access networks. A generic encapsulation protocol is therefore required for the forward link, the return link, and for mesh satellite systems. Moreover, because of the cost and the scarcity of resources, this should be as efficient and light as possible. The GSE (Generic Stream Encapsulation) protocol enables efficient transport of any protocol, originally designed for DVB-S2, that is to say on Quasi Error Free (QEF) forward links of satellite systems. This paper addresses limitations in GSE for the return link context and examines the requirements for an encapsulation mechanism for satellite systems using multiple access. This includes the return link but also mesh satellite systems and any satellite systems that uses multiple access. This paper also analyses approaches to derive requirements and provides a first analysis of these requirements.

Encapsulation Requirements for Return Links and Mesh Systems over Satellite

This paper analyses the congestion on a LEO satellite architecture with intermittent connectivity. The satellites are used to sense and gather data from ground terminals. The DTN (Delay Tolerant Networking) architecture allows the terminals to wait for the next contact when the satellite is not in the line of sight. The lack of connectivity of the network may create starvations for some stations. A model of the network is provided using Queueing Theory which allows to determine a probability of loss. This derivation proves that loss depends more on the number of terminals than on packet lifetime. The proposed scheduler and protocol allow to distribute traffic and loss fairly among stations. A testbed has been designed to validate the protocol.

http://irt.enseeiht.fr/dhaou/REFERENCES/WD_13.pdf

Martinet: A disciplinarian protocol for resource access in DTN

Bien que l'analyse ubiquitaire de donnees soit une approche prometteuse, l'analyse des donnees dans des tableurs sur des tablettes est une tâche fastidieuse en raison de la taille limitee de l'affichage et du vocabulaire tactile. Dans cet article, nous presentons la conception et l'evaluation de nouvelles techniques d'interaction reposant sur la combinaison d'une tablette contenant les donnees et d'un smartphone utilise comme mediateur entre l'utilisateur et la tablette. Pour ce faire, nous proposons d'utiliser des gestes de "stacking", c'est-a-dire de poser une arrete d'un smartphone sur l'ecran de la tablette. Le stacking est un moyen peu couteux, facile a mettre en oeuvre, efficace, et base sur l'utilisation des smartphones toujours disponibles pour ameliorer l'analyse des donnees sur des tablettes, en augmentant le vocabulaire utilise et en elargissant la surface d'affichage. Nous explorons d'abord des solutions basees sur le stacking pour delimiter le vocabulaire d'interaction possible et presenter la fabrication d'une coque conductive pour smartphone. Ensuite, nous proposons de nouvelles techniques basees sur le stacking pour realiser l'analyse de donnees d'un tableur, c'est-a-dire la creation de tableaux croises dynamiques et leur manipulation. Nous evaluons nos techniques de stacking par rapport aux interactions tactiles fournies par les applications de tableur mobiles actuelles. Nos etudes revelent que certaines de nos techniques d'interaction sont 30% plus rapides que le toucher pour creer des tableaux croises dynamiques.

Combination of tactile devices for data analytics

The Accumulation Low Schottky Barrier MOSFET (ALSB-SOI-MOS) is shown to provide a pragmatic solution to the aforementioned limitations: the junction depth issue is inherently removed as Schottky contacts do not require doped source/drain extensions silicide penetration and silicon consumption is not limited and can even provide enhanced performances material engineering provides extremely low Schottky barriers high channel doping and related effects (dopant f luctuation, hot carriers) are minimized.

Emmanuel Dubois

Papers

Electron microscopy analysis of MOSFET structures

Encapsulation Requirements for Return Links and Mesh Systems over Satellite

Martinet: A disciplinarian protocol for resource access in DTN

Combination of tactile devices for data analytics

Advanced Source/Drain Architecture using Very Low Schottky Barriers: Device Design and Material Engineering