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

Novel interactive systems such as Augmented Reality are promising tools considering the possibilities they offer, but no real development methods exist at the moment to help designers in their work. We present in this paper a design method for tightly coupling early interaction design choices and software design solutions. Based on an existing model used for abstract UI design, our work introduces a second model dedicated to the software UI specification and the model-based process used to derive one from the other. To achieve this, we present here a framework based on domain-specific models and transformations to link them and thus support the development process.

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Domain-Specific Methods and Tools for the Design of Advanced Interactive Techniques

In this study, a very dilute solution (NH4OH:H2O2:H2O 1:8:64 mixture) was employed to reduce the thickness of commercially available SOI wafers down to 3 nm. The etch rate is precisely controlled at 0.11 angstrom s(-1) based on the self- limited etching speed of the solution. The thickness uniformity of the thin film, evaluated by spectroscopic ellipsometry and by high-resolution x-ray reflectivity, remains constant through the thinning process. Moreover, the film roughness, analyzed by atomic force microscopy, slightly improves during the thinning process. The residual stress in the thin film is much smaller than that obtained by sacrificial oxidation. Mobility, measured by means of a bridge-type Hall bar on 15 nm film, is not significantly reduced compared to the value of bulk silicon. Finally, the thinned SOI wafers were used to fabricate Schottky-barrier metal-oxide-semiconductor field-effect transistors with a gate length down to 30 nm, featuring state-of-the-art current drive performance.

https://iopscience.iop.org/article/10.1088/0957-4484/19/16/165703/pdf

Characterization of ultrathin SOI film and application to short channel MOSFETs

In this paper, we demonstrate the top-down fabrication of vertical silicon nanowires networks with an ultra high density (4 x 10(10) cm(-2)), a yield of 100%, and a precise control of both diameter and location. Firstly, dense and well-defined networks of nanopillars have been patterned by e-beam lithography using a negative tone e-beam resist Hydrogen SylsesQuioxane (HSQ). A very high contrast has been obtained using a high acceleration voltage (100 kV), very small beam size at a current of 100 pA and a concentrated developer, 25% Tetramethylammonium Hydroxide. The patterns were transferred by reactive ion etching. Using chlorine based plasma chemistry and low pressure, etching anisotropy was guaranteed while avoiding the so-called 'grass effect'. This approach enabled the production of vertical silicon nanowires networks with a 20 nm diameter and a pitch of 30 nm. Lastly, the self-limited oxidation phenomenon in 1D structure has been used to perfectly control the shrinking of NWs and to obtain a Si surface free of defects induced by reactive ion etching. The silicon nanowires networks have been tapered by wet oxidation (850 degrees C) down to a diameter of 10 nm with a high aspect ratio 11.

Realization of vertical silicon nanowire networks with an ultra high density using a top-down approach.

In this paper we present a Monte Carlo research of the impact, on carrier transport, of including a dopant-segregated layer adjacent to the Schottky contact in back-to-back diodes. A comparison with a homogeneous structure is developed, evidencing that the doped layer boosts the tunneling current through the Schottky barrier, thus significantly improving the injection of carriers at the contact. We have carried out a complete study of carrier injection and transport in the region close to the reverse-biased contact together with the analysis of internal quantities such as conduction band, carrier density and electric field. The effect of temperature on the current is also evaluated. The study of the velocity distribution functions and the average number of scatterings undergone by the carriers reveals that devices with dopant segregation exhibit an enhancement of the ballistic transport in the first nanometers close to the Schottky contact.

http://iopscience.iop.org/article/10.1088/0268-1242/24/2/025022/pdf

Enhanced carrier injection in Schottky contacts using dopant segregation: a Monte Carlo research

Inefficient menu interfaces lead to system and application commands being tedious to execute in Immersive Environments. HoloBar is a novel approach to ease the interaction with multi-level menus in immersive environments: with HoloBar, the hierarchical menu splits between the field of view (FoV) of the Head Mounted Display and the smartphone (SP). Command execution is based on around-the-FoV interaction with the SP, and touch input on the SP display. The HoloBar offers a unique combination of features, namely rapid mid-air activation, implicit selection of top-level items and preview of second-level items on the SP, ensuring rapid access to commands. In a first study we validate its activation method, which consists in bringing the SP within an activation distance from the FoV. In a second study, we compare the HoloBar to two alternatives, including the standard HoloLens menu. Results show that the HoloBar shortens each step of a multi-level menu interaction (menu activation, top-level item selection, second-level item selection and validation), with a high success rate. A follow-up study confirms that these results remain valid when compared with the two validation mechanisms of HoloLens (Air-Tap and clicker).

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Emmanuel Dubois

Papers

Domain-Specific Methods and Tools for the Design of Advanced Interactive Techniques

Characterization of ultrathin SOI film and application to short channel MOSFETs

Realization of vertical silicon nanowire networks with an ultra high density using a top-down approach.

Enhanced carrier injection in Schottky contacts using dopant segregation: a Monte Carlo research

HoloBar: Rapid Command Execution for Head-Worn AR Exploiting Around the Field-of-View Interaction