Twin-screw Extrusion of Corn Flour and Soy Protein Isolate (SPI) Blends: A Response Surface Analysis

The effects of feed moisture, screw speed, and barrel temperature on physical properties of extruded corn flour and soy protein isolate (SPI) blends were investigated in a co-rotating twin-screw extruder using a response surface methodology. Corn flour and SPI were mixed with a ratio of 4:1. The screw speed was set at five levels between 60 and 140 rpm, barrel temperature between 140 °C and 180 °C, and feed moisture between 18% and 38%. All physical properties of the extruded material evaluated—included expansion ratio, bulk density, breaking strength, water solubility index, rehydration ratio, and color—were significantly (p < 0.05) affected by the three process variables. Feed moisture was the most significant variable with quadratic effects on most of the physical properties. Response surface regression models were established to correlate the physical properties of the extruded product to the process variables. Understanding the effect of these variables on the product physical properties was deemed useful for the development of protein-rich extruded products.     

Dielectric Properties of Potato Puree in Microwave Frequency Range as Influenced by Concentration and Temperature

Dielectric properties of potato flour-water dispersions (slurry) were measured in the frequency range of 500–2500 MHz by the open-ended coaxial probe method using a network analyzer as a function of concentration (10–25% w/w) and temperature (20–75^oC). Both commercial and laboratory prepared samples of potato flours were used. Results indicated that the dielectric constant (ε′) decreased with temperature and frequency while increased with concentration. The loss factor (ε″) increased with frequency and concentration; however, temperature showed mixed effect. Both ε′ and ε″ data in conventionally used microwave frequencies (915 and 2450 MHz) were studied as function of concentration and temperature for two sample types using a response surface methodology and found to follow 2^nd order polynomial models. Temperature and concentration contributed significantly on dielectric spectra of potato slurry and the sample source had some effect. A change in ε′ and ε″ above 70^oC could be attributed by starch gelatinization. Penetration depth (D_p) decreased with an increase in frequency and non-systematic with temperature. Addition of salt substantially reduced D_p of potato slurry.     

Extended Petri net-based modeling,analysis and simulation of an intelligent materials handling system

This paper describes, models, analyzes and simulates an intelligent materials handling system with diagnostic intelligence capabilities using Extended Petri Nets (EPNs). The important modeled system properties of safeness, liveness and reversibility, which guarantee that the system operates in a stable, deadlock free and cyclic manner are verified and illustrated through the simulation results, obtained through an EPN based software package. A real system, the USL CIM system, modified to function as an intelligent materials handling system with on-line adaptation capabilities is used as a case study.This work has been partially supported by the LEQSF Research Grant LEQSF (91–93) — RD-A-40. A short version of this paper has been presented at the 31st IEEE CDC, Tucson, Arizona, December 1992.     

Numerical field solution for an arbitrary asymmetrical graded-index planar waveguide

We present a numerical solution for the field amplitudes in an asymmetrical graded-index planar waveguide with an arbitrary index profile. For small index differences between the surface and bulk indexes and for large differences between the cover and surface indexes, the modes of the diffused waveguides can be described entirely in terms of normalized mode index, diffusion depth, effective modal width, and theVnumber. The results show a high degree of accuracy when checked against exact published results for the parabolic and exponential index profiles. Universal charts for the modal fields in terms of the normalized quantities are presented for profiles of practical interest, namely, Gaussian and complimentary error function index profiles. We show that the modal width, while somewhat sensitive to theVnumber, is surprisingly insensitive to the index profile. Tailoring of the index profile, therefore, does not seem important for the efficient fiber-waveguide endfire coupling. Error involved in the estimation of the phase shift at the cover-surface boundary as function of the asymmetry parameter is shown to be rather small for practical cases. Also, the discrepancy in the field distribution between an almost symmetrical and a highly asymmetrical waveguide at the cover-surface boundary is illustrated with a practical example.     

An empirical approach to evaluating dependency locality in hierarchically structured software systems

In software development, especially component-based software development, dependency locality states that relevant software components should be at shorter distances than irrelevant components. This principle is used together with modularity and hierarchy to guide the design of large-scale complex software systems. In previous work, dependency locality and its correlation with design quality were studied by statically measuring the interactions between software components. This paper presents an empirical approach to evaluating the hierarchical structure of software systems through mining their revision history. Two metrics, spatial distance and temporal distance, are adapted to measure the dependencies between software components. The correlation of spatial distance and temporal distance between software components represents a factor that influences system design quality. More specially, a well designed system hierarchy should have a significant positive correlation while a non-significant positive correlation or a negative correlation would signify design flaws. In an application of this approach, we use Mantel test to study the dependency locality of six software systems from Apache projects.     

Synthesis and characterization of TS-48, a titanium containing silica analog of ZSM-48

Crystalline titanium containing silica analog of ZSM-48 (TS-48) samples were synthesized using soluble peroxytitanate, fumed silica and diamino octane. All samples were characterized using a variety of techniques including XRD, IR, AAS, SEM, UV-Vis, XANES and catalytic testing in hydroxylation of phenol. Data suggest that titanium in these materials is linked to the framework. However, it was impossible to incorporate more than about 2 wt% Ti in the zeolite lattice. TS-48 samples prepared by this method had no activity for hydroxylation of phenol in the presence of hydrogen peroxide. The lack of activity of this material even though it showed all of the regular characteristics of other catalytically active titanium silicalites (i.e., TS-1 and TS-2) could be due either to diffusional limitations or to subtle differences in titanium environment.     

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     

Application of rank analysis of covariance methods to analysis of multiple anatomical regions with treatment for seborrheic dermatitis

This paper presents the advantages of rank analysis of covariance in contrast to the Mantel-Haenszel procedure in the presence of a covariate. In this paper, data from a clinical trial with an indication for seborrheic dermatitis, which afflicts multiple anatomical regions, is presented. This paper presents analysis performed using both the Mantel-Haenszel procedure and rank analysis of covariance for separate anatomical regions, as well as for the combined anatomical regions. The analysis for the combined anatomical regions involves weighted sums over different strata.     

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.