Comparison of semiconductor transport models using a Monte Carloconsistency test

This paper proposes a scheme to compare different transport models which are used to simulate submicron semiconductor devices. The procedure requires self-consistent Monte Carlo simulation data for a particular test device. We have compared four different hydrodynamic transport models which have been proposed recently. All four sets of hydrodynamic equations can be cast into a single form by selecting appropriate models for various transport parameters. The advantage is that we can use the same discretized set of equations to implement different transport models. We have also compared the results obtained from the Monte Carlo consistency test with those obtained by the hydrodynamic equation solver. The consistency test has been used to highlight the merits and demerits of the transport models on a common platform     

Computer-aided roll pass design for continuous billet mill

A mathematical model has been developed for computing the geometrical dimensions of square-diamond square pass sequence for a continuous billet mill. The model is based on derivation of shape and size factor from the geometry of the pass taking into account pass filling, pass rounding etc. Using these factors and a basic equation of spread for flat rolling, a governing equation incorporating angle of diamond and reduction in consecutive passes has been formulated. Newton’s substitution method has been used to solve the equation. With known reduction between consecutive passes, geometrical dimension of square and diamond passes are computed. A model has been used to calculate pass design of a finishing train of a continuous billet mill producing 60 mm square billet from 120 mm square bloom. The elongation values have been optimized by varying the apex angle of diamond. A close agreement between computed and actual values shows the validity of the model.     

Epoxidation of indene and cyclooctene on nanocrystalline anatase titania catalyst

Nanocrystalline anatase titania samples of different crystallite sizes were prepared by sol gel method using ultrasonication and calcination at different temperatures. The calcined samples were treated with H₂O₂ in order to study the role of surface hydroxyl groups present on titania in generating reactive oxygen species responsible for the epoxidation reaction. The crystallite size of the calcined samples increased from 4 to 18 nm as the calcination temperature increased from 473 to 773 K, respectively. More uniform distribution/dispersion of the nanoparticles (SEM), marginally higher surface area, better thermal stability and phase purity are some of the advantages of preparation of nanocrystalline TiO₂ by using ultrasonication. EPR spectral data on the H₂O₂-treated samples confirmed the presence of superoxide radical species. The two distinct UV bands observed at 400 and 450 nm are assigned to charge transfer of peroxide (O ₂ ²⁻ ) to Ti. FT-IR spectral data show that the surface hydroxyl groups are the active sites in the generation of reactive oxygen species. The catalytic activity was evaluated in a series of epoxidation reactions using indene and cyclooctene as substrates and aqueous H₂O₂ as oxidant. The activity was found to decrease with increase in the calcination temperature of the samples, obviously due to an increase in crystallite size and a decrease in surface hydroxyl groups. The nanoparticle titania samples show better conversion and selectivity than the standard titania (Degussa P-25). The kinetic studies revealed that the reaction followed a pseudo first order kinetics in excess of H₂O₂.     

Role of Biomaterials and Controlled Architecture on Tendon/Ligament Repair and Regeneration

Engineering synthetic scaffolds to repair and regenerate ruptured native tendon and ligament (T/L) tissues is a significant engineering challenge due to the need to satisfy both the unique biological and biomechanical properties of these tissues. Long-term clinical outcomes of synthetic scaffolds relying solely on high uniaxial tensile strength are poor with high rates of implant rupture and synovitis. Ideal biomaterials for T/L repair and regeneration need to possess the appropriate biological and biomechanical properties necessary for the successful repair and regeneration of ruptured tendon and ligament tissues.     

Augmenting the house of quality with engineering models

To develop successful products the Voice of the Customer must be explicitly considered in the design process. The House of Quality (HOQ) is an increasingly popular structured methodology for ensuring customer focus. Two important steps of the product development process in which the HOQ is used are (1) setting engineering targets and (2) identifying the inherent tradeoffs in a design. We believe that these two activities cannot be performed reliably in actual practice unless the HOQ is used in conjunction with objective engineering models of product performance. In this paper, we substantiate this claim using an example drawn from a real design project. The potential benefits of augmenting the HOQ with engineering models are explained and a single representation which facilitates their combined use is presented.     

Neural network classification of late gamma band electroencephalogram features

This paper investigates the feasibility of using neural network (NN) and late gamma band (LGB) electroencephalogram (EEG) features extracted from the brain to identify the individuality of subjects. The EEG signals were recorded using 61 active electrodes located on the scalp while the subjects perceived a single picture. LGB EEG signals occur with jittering latency of above 280 ms and are not time-locked to the triggering stimuli. Therefore, LGB EEG could only be computed from single trials of EEG signals and the common method of averaging across trials to remove undesired background EEG (i.e. noise) is not possible. Here, principal component analysis has been used to extract single trials of EEG signals. Zero phase Butterworth filter and Parsevals time-frequency equivalence theorem were used to compute the LGB EEG features. These features were then classified by backpropagation and simplified fuzzy ARTMAP NNs into different categories that represent the individuality of the subjects. The results using a tenfold cross validation scheme gave a maximum classification of 97.33% when tested on 800 unseen LGB EEG features from 40 subjects. This pilot investigation showed that the method of identifying the individuality of subjects using NN classification of LGB EEG features is worth further study.

A Novel Single Step Selective Synthesis of 4-Hydroxybenzophenone (4-HBP) Using Zeolite H-Beta

The single step selective synthesis of 4-hydroxybenzophenone (4-HBP/2-HBP = 2.1, selectivity for 4-HBP among 2- and 4-HBP = 67.7 wt%) at 95.3 wt% conversion level of benzoic anhydride has been investigated for the first time by the benzoylation of phenol using benzoic anhydride as benzoylating agent and zeolite H-beta as catalyst at 493 K in a Parr autoclave at autogenous pressure.