Modeling of MOSFET parasitic capacitances, and their impact on circuit performance

We study layout dependent, parasitic capacitance contributions of MOSFETs with 3D simulations, and show that these contributions are for narrow and short devices comparable to intrinsic contributions. The performance of 65-nm technology is strongly affected by these components, and should therefore be modeled accurately in circuit simulations. We propose a methodology how to accurately and consistently model them in a design flow. The methodology is validated with ring oscillator measurements.     

Permittivity determination of liquid materials using waveguide measurements for industrial applications

There is a need for a simple and relatively inexpensive microwave method for complex permittivity, ?, determination of liquid materials in industrial applications. Measurement cables that connect the measurement cell to the measuring instrument (usually a vector network analyser) may be either subject to severe phase instability particularly if they are long or metrology-grade cables are not available, or subject to thermal variation. In these instances, calibration techniques based on complex scattering parameter measurements may drastically suffer from extension of the reference plane to the boundaries of the measurement cell or sample end surfaces. In such situations, amplitude-only methods based on simplified calibration techniques such as response calibration are appropriate and very feasible. These methods have applications in industry such as thickness measurement and disbonding and delamination detection. The motivation of this study is to investigate a suitable method for ? determination of liquid materials using amplitude-only waveguide measurements. The analysis is restricted to lossy dielectric materials, which possess large enough attenuation such that the multiple reflections between their two end surfaces can be neglected. We derived an equation in terms of the loss tangent of these materials for selecting a suitable material thickness. We presented two approximations (frequency-independent and power-series representation) for ? determination of these materials. For validation of the method, we measured the ? of methanol and commercially available antifreeze solution by our method using a simple (frequency response) calibration and by another waveguide method using the thru-reflect-line calibration.     

Polyphenol oxidase potentials of three wild mushroom species harvested from Lişer High Plateau,Trabzon

Crude enzyme extracts were prepared from Armillaria mellea (A. mellea), Lepista nuda (L. nuda) and Hypholoma fasciculare (H. fasciculare), which were harvested from the Li?er High Plateau-Maçka (Trabzon, Turkey). The crude polyphenol oxidase (PPO) extracts from each mushroom were highly active against 4-methylcatechol. Native polyacrylamide gel electrophoresis, stained by L-3,4-dihydroxyphenylalanine, showed the polyphenol oxidase potentials. The optimum pH value, for each enzyme, was 7.0. When enzyme extracts were incubated at pH 7.0 for 24 h at 4 °C, it was observed that L. nuda and H. fasciculare enzyme activities decreased by about 26% and 18%, respectively, but, A. mellea enzyme activity increased by about 11%. The temperature optima of A. mellea, L. nuda and H. fasciculare were, respectively, 30, 30 and 20 °C. Cr³⁺ and Cu²⁺ ions inhibited each activity. Also, sodium metabisulphite and ascorbic acid were strong inhibitors of the enzyme activities.     

A novel, robust DSP-based indirect rotor position estimation for permanent magnet AC motors without rotor saliency

This paper proposes and implements a novel rotor position sensorless technique for PM AC motor drives, which allows acceleration from standstill and can operate under various practical operating conditions including transient speed changes. The technique developed here relies on the measurement of the phase voltages and currents of the motor. It uses the incremental values of flux linkage, and the back-EMF functions to estimate incremental rotor position. Using a phase-locked loop (PLL) algorithm, an internal closed-loop correction algorithm can correct rotor position estimation drift, which may be due to the motor parameter variations or measurement inaccuracies. The method is implemented in closed-loop using a digital signal processor (DSP), and details of the implementation are provided in the paper. To demonstrate accuracy, robustness and reliability of the position estimation scheme, the paper presents a number of real-time experimental results, including dynamic operating conditions.     

Synthesis and characterization of conducting copolymers of quinoxaline derivatives

Electrochemical copolymerizations of 2,3‐di(2‐thienyl)quinoxaline (M1), 6‐methyl‐2,3‐di(2‐thienyl)quinoxaline (M2), and 2,3‐di(2‐thienyl)quinoxaline‐6‐yl)(phenyl)methanone (M3) with 3,4‐ethylenedioxy thiophene (EDOT) were carried out in CH₃CN/TBABF₄ (0.1M) solvent‐electrolyte couple via potentiodynamic electrolysis. The obtained copolymers were characterized by cyclic voltammetry (CV), Fourier transform‐infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry analyses (TGA). The conductivity measurements of copolymers and PEDOT were performed by the four‐probe technique. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of Deposition Pressure (O2) on the YBCO (Y123) Thin Films Prepared by Pulsed Laser Deposition

In this paper, the influence of oxygen pressure on film quality and superconducting properties of YBa₂Cu₃O_7?δ (YBCO-Y123) thin films prepared by Pulsed Laser Deposition (PLD) was investigated. For this purpose, YBCO thin films were deposited on polished LaAlO₃ (l00) (LAO) substrates at three different oxygen pressures (150, 200, and 250 mTorr). X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques were used to make comparative studies of film microstructure. Except for oxygen pressures, all other variables such as number of pulses, repetition rate, deposition temperature, heating and cooling rate, target-substrate distance, laser excitation energy, annealing temperature, and annealing pressure were fixed. For this fixed set of parameters, SEM, XRD analysis, and AC susceptibility measurements of these films revealed that the crystal structure quality and superconducting properties of YBCO thin films are optimum at the oxygen deposition pressure of 150 mTorr. As the deposition pressure increased, Y₂BaCuO₅ (Y211) phase peaks were seen in XRD patterns. The reason for this was believed to be caused by decreased concentration of CuO and BaO as determined by Energy Dispersive X-Ray Spectroscopy (EDX) of thin films.     

Fuzzy multiple objective decision making approach to prioritize design requirements in quality function deployment

Quality function deployment (QFD) is a customer-oriented design tool for developing new or improved products to increase customer satisfaction by integrating marketing, design engineering, manufacturing, and other related functions of an organization. QFD focuses on delivering value by taking into account customer needs and then deploying this information throughout the development process. Although QFD aims to maximize customer satisfaction, technology and cost considerations limit the number and the extent of the possible design requirements that can be incorporated into a product. This paper presents a fuzzy multiple objective programming approach that incorporates imprecise and subjective information inherent in the QFD planning process to determine the level of fulfilment of design requirements. Linguistic variables are employed to represent the imprecise design information and the importance degree of each design objective. The fuzzy Delphi method is utilized to achieve the consensus of customers in determining the importance of customer needs. A pencil design example illustrates the application of the multiple objective decision analysis.     

DETERMINATION OF ADSORPTION AND KINETIC PARAMETERS FOR SYNTHESIS OF ISOBUTYL ACETATE CATALYZED BY AMBERLITE IR-122

In the present study, the kinetics of esterification of acetic acid with isobutanol was studied by using Amberlite IR-122 as an acid catalyst. Experiments were carried out in a stirred batch reactor in dioxane at different temperatures (323 to 348 K) under atmospheric pressure. The equilibrium constant was found to be constant as 4 in the temperatures ranging from 323 to 367 K. The possible mechanism of reaction was mathematically treated using the theories of the Eley-Rideal model based on inhibition by water and isobutanol on the resins. The reaction rate constants and the adsorption coefficients for isobutanol and water were determined from the experimental data at the same temperature intervals. Furthermore, the activation energy of the esterification reaction was found to be 50.5 kJ/mol. The heat of adsorption for isobutanol and water was also calculated as ? 50.9 kJ/mol and ? 18.9 kJ/mol, respectively.     

Field-weakening performance of interior permanent-magnet motors

This paper compares the field-weakening performance under rated and overload conditions of synchronous reluctance and interior permanent-magnet motors against that of a baseline 2.2-kW induction machine. Four prototype rotors based on axially laminated and multiple-barrier designs were built and tested in the same induction machine stator. Field-weakening performance was estimated based on 50-Hz load tests at reduced voltage. It was found that the performance of the axially laminated synchronous reluctance machine was comparable with the induction machine while the interior permanent-magnet motors offered significantly better output power above rated speed. The multiple-barrier interior permanent-magnet motor design gave the most promising field-weakening performance.     

Integrative analysis of cancer pathway progression and coherence

We analyzed the cancer pathways in the KEGG (Kyoto Encyclopedia of Genes and Genomes) database. The database provides a collective of signaling pathway members involved in cancer progression. However, the KEGG cancer pathways, unlike signaling pathways, have not been analyzed extensively with gene expression and mutation data. We transformed the colorectal cancer pathway into discrete X and Y scales and analyzed the relative expression levels of adenoma and carcinoma samples as well as the distribution of mutation targets. The X scale corresponds to the downstream location in a pathway, whereas the Y scale corresponds to the stage of the tumor. The gene expression values of the early stage pathway members are significantly higher than of the rest of the pathway members in colorectal adenoma tissues. The colorectal cancer pathway shows some degree of coherence in the carcinoma samples. The correlated gene pairs responsible for the coherence of the colorectal cancer pathway in the carcinoma samples are supported, in part, by the literature and may suggest novel regulatory associations. Finally, there are more mutation targets in the nucleus as well as the late tumor stages of the KEGG colorectal cancer pathway.