27918831
Universality of mobility-gate field characteristics of electrons in the inversion charge layer and its application in MOSFET modeling
A mobility curve for electrons in a MOSFET inversion charge layer is determined from measured drain current of transistors produced by a wide range of MOS technologies. A comparison between this mobility curve and previously published results shows that a truly universal mobility curve does not exist and only local universal mobility curves can be expected, i.e. unique mobility curves which are valid over a finite range of MOS technologies and/or over a particular set of fabrication facilities. The curve's basic characteristic of being technology-independent over a wide range of process variation points out the potential of using such a local universal mobility curve as a powerful basis for developing predictive device modeling tools. This potential is demonstrated for an analytical MOSFET model and a two-dimensional device simulator where the mobility models have the general characteristics of experiment-based local universal mobility curves. >
30889656
A compact IGFET model-ASIM
A description is given of ASIM (ATT i.e. the effects of mobility reduction, carrier velocity saturation, and channel length modulation are included in both. The ASIM model accounts for effects due to device dimensions and temperature. The performance of ASIM under DC and transient conditions is evaluated by comparing the current and voltage at the terminals with that of detailed physical simulations and measurements. The results agreed well with that of two-dimensional device simulations and measurements. >
3673449
BestChoice: A Decision Support System for Supplier Selection in e-Marketplaces
A growing number of companies are outsourcing their purchasing processes to independent purchasing agencies. These agencies now have to process an ever increasing number of purchase requests each day. The conventional methods of selecting the right suppliers for the purchase requests incur heavy human and time costs. We have designed and implemented BestChoice, a decision support system for supplier selection. It allows the evaluator to create rules for supplier evaluation based on the Multi Attribute Utility Theory, a theory for evaluating the utility of alternatives. BestChoice provides rule structures that can be saved and reused for similar selection cases. The architecture and selection rules of BestChoice are presented. Performance of BestChoice at one of the largest procurement agencies is analyzed.
566220
Endomorphic modelling for two-dimensional time-varying autoregressive model signals
Physical signals are often non-stationary. We assume that images are non-stationary and each pixel is the output of a different set of two-dimensional autoregressive (AR) model coefficients; therefore, texture cannot be characterised by applying AR modelling techniques to the entire image. A multistage modelling technique, which appears in the literature as "endomorphic modelling", is applied to this kind of signal. The signal is divided into sub-sets of samples and each sub-set is modelled using an AR model. A new image is formed using the same AR model coefficient estimated from different blocks, then the new image is re-modelled using AR models again. This process ends when the variance of the estimated parameters is sufficiently small. The simulation results show that the variances obtained from the estimated coefficients at the second stage are much smaller than the ones from the first stage
15031491
Congestion controlled adaptive lightweight multicast in wireless mobile ad hoc networks
The use of contention-based MAC protocols combined with hidden terminal problems make multi-hop wireless ad hoc networks much more sensitive to load and congestion than wired networks or even wireless cellular networks. In such an environment, we argue that multicast reliability cannot be achieved solely by retransmission of lost packets as is typically done in wired networks with protocols such as SRM. We contend that in order to achieve reliable multicast delivery in such networks, besides reliability mechanisms, we must also consider jointly two components: reliability and congestion control. In this paper, we propose CALM, a congestion controlled, adaptive, lightweight multicast transport protocol and show that congestion control alone can significantly improve reliable packet delivery in ad hoc networks when compared to traditional "wired" reliable multicast protocols.
852427
Multisensor raster and vector data fusion based on uncertainty modeling
We propose a new methodology for fusing temporally changing multisensor raster and vector data by developing a spatially and temporally varying uncertainty model of acquired and transformed multisensor measurements. The proposed uncertainty model includes errors due to (1) each sensor by itself, e.g., sensor noise; (2) transformations of measured values to obtain comparable physical entities for data fusion and/or to calibrate sensor measurements; (3) vector data spatial interpolation that is needed to match different spatial resolutions of multisensor data; and (4) temporal interpolation that has to take place if multisensor acquisitions are not accurately synchronized. The proposed methodology was tested using simulated data with varying (a) amount of sensor noise, (b) spatial offset of point sensors generating vector data, and (c) model complexity of the underlying physical phenomenon. We demonstrated the multisensor fusion approach with a data set from a structural health monitoring application domain.
5959481
Grid services for earthquake science
We describe an information system architecture for the ACES (Asia–Pacific Cooperation for Earthquake Simulation) community. It addresses several key features of the field—simulations at multiple scales that need to be coupled together; real-time and archival observational data, which needs to be analyzed for patterns and linked to the simulations; a variety of important algorithms including partial differential equation solvers, particle dynamics, signal processing and data analysis; a natural three-dimensional space (plus time) setting for both visualization and observations; the linkage of field to real-time events both as an aid to crisis management and to scientific discovery. We also address the need to support education and research for a field whose computational sophistication is rapidly increasing and spans a broad range. The information system assumes that all significant data is defined by an XML layer which could be virtual, but whose existence ensures that all data is object-based and can be accessed and searched in this form. The various capabilities needed by ACES are defined as grid services, which are conformant with emerging standards and implemented with different levels of fidelity and performance appropriate to the application. Grid Services can be composed in a hierarchical fashion to address complex problems. The real-time needs of the field are addressed by high-performance implementation of data transfer and simulation services. Further, the environment is linked to real-time collaboration to support interactions between scientists in geographically distant locations. Copyright © 2002 John Wiley & Sons, Ltd.