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Parameter Extraction (parameter + extraction)

Distribution by Scientific Domains

Physics and Astronomy	37%

Selected Abstracts

Optimizing process allocation of parallel programs for heterogeneous clusters

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 4 2009
Shuichi Ichikawa
Abstract The performance of a conventional parallel application is often degraded by load-imbalance on heterogeneous clusters. Although it is simple to invoke multiple processes on fast processing elements to alleviate load-imbalance, the optimal process allocation is not obvious. Kishimoto and Ichikawa presented performance models for high-performance Linpack (HPL), with which the sub-optimal configurations of heterogeneous clusters were actually estimated. Their results on HPL are encouraging, whereas their approach is not yet verified with other applications. This study presents some enhancements of Kishimoto's scheme, which are evaluated with four typical scientific applications: computational fluid dynamics (CFD), finite-element method (FEM), HPL (linear algebraic system), and fast Fourier transform (FFT). According to our experiments, our new models (NP-T models) are superior to Kishimoto's models, particularly when the non-negative least squares method is used for parameter extraction. The average errors of the derived models were 0.2% for the CFD benchmark, 2% for the FEM benchmark, 1% for HPL, and 28% for the FFT benchmark. This study also emphasizes the importance of predictability in clusters, listing practical examples derived from our study. Copyright © 2008 John Wiley & Sons, Ltd. [source]

High-Performance Organic Field-Effect Transistors

ADVANCED MATERIALS, Issue 14-15 2009
Daniele Braga
Abstract With the advent of devices based on single crystals, the performance of organic field-effect transistors has experienced a significant leap, with mobility now in excess of 10,cm2 V,1 s,1. The purpose of this review is to give an overview of the state-of-the-art of these high-performance organic transistors. The paper focuses on the problem of parameter extraction, limitations of the performance by the interfaces, which include the dielectric,semiconductor interface, and the injection and retrieval of charge carriers at the source and drain electrodes. High-performance devices also constitute tools of choice for investigating charge transport phenomena in organic materials. It is shown how the combination of field-effect measurements with other electrical characterizations helps in elucidating this still unresolved issue. [source]

Novel broadband asymptotic waveform evaluation method and its applications in parameter extraction

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2007
Guo-Bing Han
Abstract A new technique to estimate the effective bandwidth of the asymptotic waveform evaluation (AWE) method is proposed, which guarantees the reliable application of AWE in a certain region. Furthermore, based on the effective bandwidth estimation, we develop a novel broadband AWE method, which is an extension and improvement of the conventional AWE method. The new method selects the multiple expansion points automatically by a simple compare algorithm and then implements the AWE process on every expansion point, thereby expanding the variable bandwidth of the AWE greatly. The variable here can be frequency, structure dimension, material parameter, etc. In the end, two examples of parameter extraction of microwave structures are given, which demonstrate that the new method has high efficiency and good accuracy in a broad band. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. [source]

Model description and parameter extraction of on-chip spiral inductors for MMICs

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2004
W. Y. Yin
Abstract A statistical description of the global performance of on-chip spiral inductors, based on extensive measurement is presented. These inductors were fabricated with different turn numbers or track lengths/track widths, but with the same spacing. From the S parameters measured using a de-embedding technique, the inductance L, Q factor, self-resonance frequency, and figure-of-merit indicator (FMI) of these inductors are determined. Various local scalable formulas are obtained in order to describe the features of these inductors. Based on extensive parametric studies, certain ways to improve these inductor performances can be found. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 111,121, 2004. [source]

Light as a Controlling Tool

LASER TECHNIK JOURNAL, Issue 1 2010
White Light Interferometry in Quality Assurance of Photovoltaic Samples
The photovoltaic industry is characterized by a permanent, substantial growing during the last years. Today improving efficiencies and reduction of manufacturing cost of solar cells is essential for the success in the competitive market. The reduction of manufacturing costs is associated with high volume manufacturing of the solar cells by perpetuation of high quality standards and requirements for small tolerances. Measurements of the topography of solar cells now start to play an important role in the quality assurance of the manufacturing process. It allows the three-dimensional mapping of a complete area with subsequent parameter extraction: so the efficiency of a solar cell depends on the wafer structure: Perfect smooth surfaces absorb less photons than surfaces with a certain, optimized roughness, whereas protecting layers should be as smooth and flat as possible. Similar to all Microsystems the structures can be investigated and compared to the target values: examples are layer thickness, widths and depths of structured lines, the volume-determination of hollows, defects, pores or abrasion/deposition rates. It also encompasses the 3D profile of printed circuit board tracks or special structures for sophisticated high efficiency photovoltaic elements. [source]

Simplified heat exchange model for semiconductor laser diodes thermal parameters extraction

LASER PHYSICS LETTERS, Issue 11 2005
P. S. André
Abstract By investigating the heat flow mechanism in a semiconductor laser diode, we demonstrate a comprehensive technique for optical device thermal parameters extraction to be used in the prediction of the laser performance This accurate and precise heat exchange model takes into account the relevant heat exchange mechanism and mechanical considerations of the laser diode mounting. We measured the thermal response of a semiconductor laser diode attach to a substrate, deriving from those the device thermal parameters such as heat capacity and thermal conductance for the device and subtract. From the estimated values a prediction of the real laser temperature response is obtained directly from the measurements realized in the substrate. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]