可重定位的基于事务的系统级验证

功能验证已经成为开发SoC的主要问题。随着一些复杂SoC的规模超过两千万门，以及对开发和集成嵌入式软件的需求持续增加，软件模拟器已经力所不及。在设计过程需要几百万个时钟周期来充分测试和验证软件功能的情况下，软件仿真器的性能下降到1-5Hz。按照这种速率，软件调试需要几年的时     

Accuracy of approximations in MOSFET charge models

This paper analyzes the results of common approximations made in MOSFET charge modeling. The basis for the comparison is a charge-sheet model that is valid in all regions of operation. We show that proper modeling of surface potential as a function of position along the channel is more important for capacitance coefficient modeling accuracy than partitioning of inversion charge between source and drain. In addition, we show that there is a numerical error in previous charge-sheet formulations, and provide a solution for this problem     

Informal learning with PDAs and smartphones

Abstract There has been increasing interest in informal learning in recent years alongside interest in how such learning can be supported by technology. However, relatively little is known about the extent to which adults make use of their own mobile devices to support informal learning. In this study, a survey was used to investigate whether, and to what extent, experienced users of mobile devices use their mobile devices to support intentional informal learning. If so, do they make use of mobile device connectivity to support opportunistic informal learning and does such connectivity support or encourage collaborative informal learning? Experienced mobile device users were recruited from web forums and business, and asked whether they used their devices to support informal learning. A pattern of learning uses emerged, some of which deployed the mobile device capabilities relatively unchanged, others triggered adaptations to typical learning activities to provide a better fit to the needs of the learner. These informal learning activities provided the basis for the design of a flexible mobile learning framework that can be extended to support developments in mobile technology, and increasing use of Web 2.0 technologies by informal learners.     

A Compact Model for Valence-Band Electron Tunneling Current in Partially Depleted SOI MOSFETs

The valence-band electron (EVB) tunneling current in partially depleted silicon-on-insulator (SOI) MOSFETs increases as the gate oxide gets thinner and affects the dynamic behavior of devices and circuits. We present an engineering model of EVB tunneling current based on the surface-potential formulation. The new model is implemented in a SOI MOSFET compact model and is used to study the impact of EVB tunneling on circuit performance. Simulations of stacked logic gates show that the EVB tunneling current not only boosts circuit switching speed but also mitigates the history dependence of propagation delays     

Maximal connected sets—application to microcell CDMA

Current trends in personal and data communication networks favour code division multiple access (CDMA) as a solution to spectral congestion. This is because of enhanced capacity, security, network flexibility, simplified protocol, and relative immunity to propagation induced errors such as multipath and interference, as compared with traditional frequency division multiple access (FDMA). Various CDMA schemes have been proposed and described in relation to VSAT systems, local area microcells,² and cellular telephones. Additionally, numerous product applications have emerged in the areas of modems, voice links and wireless local exchanges. These systems require inter- and intra-cell control. By contrast, the scheme presented in this paper places no reliance on intercell protocol. It enables new cells to be added to the network without any impact on the hardware. Network reconfiguration requires software changes only. Therefore, the scheme is appropriate to systems which demand flexibility with minimum overheads.     

A single-piece C∞-continuous MOSFET modelincluding subthreshold conduction

A simple yet powerful technique that transforms regional compact (algebraic) MOSFET models into single-piece C_∞-continuous models is introduced. The technique significantly improves MOSFET models by removing kinks and glitches at the boundaries between the subthreshold, triode, and saturation regions of operation. In addition, the technique adds subthreshold conduction modeling to models that lack such a capability. The authors show the technique by extending a simple MOSFET model, which is three piece and does not model subthreshold conduction, to become a single-piece model that includes subthreshold conduction     

Dynamic control and prototyping of parallel algorithms forintermediate- and high-level vision

Developing parallel algorithms for intermediate and high levels of computer vision systems is addressed. Because the algorithms are complex and the nature and size of the input and output data sets vary for each application, the authors have directly developed parallel algorithms for dynamic control of both processing and communication complexity during execution. They have also examined the merits of functional prototyping and transforming programs into imperative execution code for final implementation. To evaluate and give direction to their work, they have implemented algorithms for plane detection and object recognition on a flexible transputer network     

Afterburn Ignition Delay and Shock Augmentation in Fuel Rich Solid Explosives

We present experimental and computational results that explain some aspects of measured energy release in explosions of unconfined trinitrotoluene [TNT, C₆H₂(NO₂)₃CH₃], and an aluminum‐containing explosive formulation, and show how this energy release can influence shock wave velocities in air. In our interpretation, energy release is divided into early, middle, and late time regimes. An explanation is provided for the interdependence of the time regimes and their influence on the rate at which energy (detonation/explosion and afterburn) is released. We use a merging of the thermodynamic and chemical kinetic processes that predicts how chemical kinetics may determine the time delay of the afterburn of combustible gases produced by the initial detonation/explosion/fast reaction. The thermodynamic computer code CHEETAH is used to predict gaseous and solid products of early time energy release, and a chemical kinetic reaction mechanism (CHEMKIN format) is used to describe the subsequent afterburn of the gas phase products in air. Results of these calculations are compared with field measurements of unconfined explosions of 2 kg charge weights of TNT and an aluminum‐containing explosive formulation.     

3D modelling of Ti–6Al–4V linear friction welds

Linear friction welding (LFW) is a solid-state joining process that significantly reduces manufacturing costs when fabricating Ti–6Al–4V aircraft components. This article describes the development of a novel 3D LFW process model for joining Ti–6Al–4V. Displacement histories were taken from experiments and used as modelling inputs; herein is the novelty of the approach, which resulted in decreased computational time and memory storage requirements. In general, the models captured the experimental weld phenomena and showed that the thermo-mechanically affected zone and interface temperature are reduced when the workpieces are oscillated along the shorter of the two interface contact dimensions. Moreover, the models showed that unbonded regions occur at the corners of the weld interface, which are eliminated by increasing the burn-off.