Surface effects in sem measurements of hole diffusion length in n-GaAs

In scanning-electron microscope injection measurements of hole diffusion lengths in n-type gallium arsenide Schottky barrier junctions the results obtained depend strongly on the surface treatment (exposure to air, H₂0, or HC1 treatments) after cleaving. The effect is attributed to band bending causing a p-region on the surface which allows collection of minority carriers produced far from the junction. Scanning of the semiconductor surface by the 25 keV electron beam for a few minutes prior to diffusion length measurements is found to remove these contamination effects and give reliable and consistent results.     

Judgments of consensus during group discussion.

6 groups of Ss held discussions during which the individuals' opinions and estimates of the group consensus were privately taken on various issues. "The degree of estimation accuracy achieved was not noticeably different from the accuracy found by other investigators under conditions of no discussion." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantifying Software Validity by Sampling

The point of all validation techniques is to raise assurance about the program under study, but no current methods can be realistically thought to give 100% assurance that a validated program will perform correctly. There are currently no useful ways for quantifying how 'well-validated' a program is. One measure of program correctness is the proportion of elements in the program's input domain for which it fails to execute correctly, since the proportion is zero i.f.f. the program is correct. This proportion can be estimated statistically from the results of program tests and from prior subjective assessments of the program's correctness. Three examples are presented of methods for determining s-confidence bounds on the failure proportion. It is shown that there are reasonable conditions (for programs with a finite number of paths) for which ensuring the testing of all paths does not give better assurance of program correctness.     

Area decomposition for electromechanical models of power systems

Coherency and time scale properties of power system models are shown to be related by the dichotomic solution of a matrix Riccati equation. A grouping algorithm is proposed which reduces the area decomposition problem to obtaining a basis for the slow subsystem and performing a Gaussian elimination. Since the slow coherency measure allows for a lack of coherency in fast parts of machine transients, the resulting area decomposition is independent of fault locations. The procedure is illustrated by a 16-machine example.     

Singular perturbation analysis of systems with sustained high frequency oscillations

Using singular perturbation techniques, a system with high frequency oscillations is decomposed into two lower order subsystems, one containing only the slowly varying part and the other containing only the fast oscillatory part. Eigenvalue and state approximations achieved by the subsystems are given. A mass-spring-damper example shows that a stiff spring can be regarded as a perturbation of a rigid rod and an interconnected power system example illustrates the occurrence of coherency and inter-machine oscillations.     

Surface modification by electron beam glazing

Experiments were conducted with three common steels, namely AISI 1045, AISI 4150 and AISI 1090, using an electron beam as an energy source to provide rapid superficial surface fusion. Beam scanning velocities of 75–2592 cm s^-1 were used. Increasing the beam scan rate resulted in an increased hardness for scan rates of up to 1300 cm s^-1. This scan rate gives a calculated cooling rate in excess of 10⁷ °Cs^-1.Microhardness was used as a measure of the performance resulting from the rapid solidification rates obtained. The measured Vickers hardness was converted to and reported as the Rockwell C scale hardness.The fused layer appears as a metastable solid solution with a fine precipitate associated with the overlap of fused paths. The Vickers hardness was found to be significantly harder (1100 HV compared with 700 HV) than that of the same materials treated by a conventional quench. The treated layer also appears to have good fracture toughness in that adjacent and superimposed hardness indentations and those near an edge did not induce cracking.Post-fusion thermal treatments at 200 and 590 °C and a complete quench and temper all resulted in a lower measured hardness.     

Second phase formation at microvoids and gas atom entrapment at fusion reactor first wall surfaces

Results of cascade production and annealing studies for iron are projected to the currently considered fusion reactor first wall materials. Collision cascades initiated by primary knock-on atoms (PKA) with energies above 50 keV, in iron, separate into distinct subregions. Most PKA produced during fission reactor neutron irradiation have energies below 50 keV, but the energies of PKA produced by 14.1 MeV neutron irradiation commonly lie in the 50–500 keV range in iron and vanadium alloys. Computer experiment simulation indicates that, when present, carbon, silicon, and nitrogen, freed by irradiation from bulk precipitates, should tend to re-precipitate on the facets of microvoids which form in cascade subregions during short-term annealing.     

Multiattribute Water Resources Decision Making

Field reconnaissance with decision makers in San Angelo, Texas led to the selection of dependability, environmental degradation, economic growth potential, quantity, quality, cost, social acceptance and flexibility as the important attributes to be considered in their supplementary water resource development decision problem. The decision analysis solution to San Angelo's decision problem has been determined and is presented. A sensitivity analysis of utility assessments was conducted with the use of Monte-Carlo simulation.     

A Review of infrared spectroscopic studies of vapor-deposited dielectric glass films on silicon

Vibrational studies of a variety of thin dielectric glass films relevant to the silicon technology are reviewed. Attention is focused on those results and structural infor-mation obtained by direct transmission of materials vapor-deposited on single-crystal silicon substrates in the infra-red region 250 to 4000 cm^-1. In particular, the structure and bonding in some simple CVD binary silicate films are discussed in some detail in light of the recent vibrational analyses performed on the borosilicate and phosphosilicate systems.     

Multiprocessor Architecture for Rapid EEG Frequency Analysis

A multicomputer array is described that speeds up the processing of spectral representation for the EEG.