Effect of ion energy on hydrogen diffusion in n- and p-GaAs

The ion energy during electron cyclotron resonance (ECR) plasma hydrogenation is found to have a strong effect on both the effective diffusivity and solubility of hydrogen in n⁺ and p⁺ GaAs. For fixed plasma exposure conditions (30 min, 250°C) the diffusion depths for -150 V acceleration voltage are ~50 and ~100% larger, respectively, in p⁺- and n⁺-GaAs compared to 0 V acceleration voltage. The smaller incorporation depths at lower ion energy coincide with much larger peak hydrogen concentrations and higher apparent thermal stability of passivated dopants     

Resurgence of derived stimulus relations

Resurgence has been shown in human and nonhuman operant behavior, but not in derived relational responses. The present study examined this issue. Twenty-three undergraduates were trained to make conditional discriminations in a three-choice matching-to-sample paradigm. The training resulted in three equivalence classes, each consisting of four arbitrarily configured visual stimuli. The same 12 stimuli were then reorganized, and the conditional discrimination training was repeated such that three new classes were possible. In a subsequent test of derived relations, most subjects showed response patterns that were consistent with the altered conditional discriminations. Subjects were then exposed to conditional discrimination trials under extinction. Most subjects continued to respond consistently with the most recently reinforced conditional discrimination trials. During the next phase, subjects were exposed to symmetry and equivalence trials. Responses consistent with the most recent training produced feedback saying that the responses were incorrect, whereas other responses produced no feedback. Most subjects showed a resurgence of responding that was consistent with their earlier training. Finally, subjects were exposed to conditional discrimination trials carried out in extinction. Most subjects continued to show a resurgence of responding that was consistent with their early training.     

The future of behavior therapy.

Predicts the future of behavior therapy, focusing on theoretical development, therapeutic techniques, and empirical research. The importance of cognitive and affective processes in behavior change will attract increasing attention. Already one of the most widely adopted approaches, behavior therapy will be used to treat an expanded range of psychiatric disorders and health problems. Research will focus on comparative outcome studies and provide probes for investigating the nature of specific disorders and the mechanisms of therapeutic change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An investigation into the performance and cost effectiveness of thermosyphon solar water heaters

In this paper, the TRNSYS Simulation Program is used to investigate the monthly and annual solar fraction of a Thermosyphon Solar Water Heater and to evaluate its economic viability in terms of its life cycle savings over a conventional water heating system. The results of the simulation indicate that the yearly solar contribution of the system ranges from 63% for a high hot water consumption profile to 89% for a low consumption pattern. The payback period of the system is as low as 3 years when compared to electric water heating systems. As long as the competitor is diesel oil, the payback period increases to 7–9 years, depending on the hot water consumption profile used.     

An LP-based heuristic procedure for the generalized assignment problem with special ordered sets

The generalized assignment problem with special ordered sets (GAPS2), is the problem of allocating n tasks to m time-periods, where each task must be assigned to a time-period, or shared between two consecutive time-periods. For reasonably large values of m and n the NP-hard combinatorial problem GAPS2 becomes intractable for standard mathematical programming software, hence there is a need for heuristic algorithms to solve such problems. It will be shown how an LP-based heuristic developed previously for the well-established generalized assignment problem can be modified and extended to solve GAPS2. Encouraging results, in terms of speed and accuracy, in particular when compared to an existing heuristic for GAPS2, are described.     

A wavelet-based procedure for process fault detection

To detect faults in a time-dependent process, we apply a discrete wavelet transform (DWT) to several independently replicated data sets generated by that process. The DWT can capture irregular data patterns such as sharp "jumps" better than the Fourier transform and standard statistical procedures without adding much computational complexity. Our wavelet coefficient selection method effectively balances model parsimony against data reconstruction error. The few selected wavelet coefficients serve as the "reduced-size" data set to facilitate an efficient decision-making method in situations with potentially large-volume data sets. We develop a general procedure to detect process faults based on differences between the reduced-size data sets obtained from the nominal (in-control) process and from a new instance of the target process that must be tested for an out-of-control condition. The distribution of the test statistic is constructed first using normal distribution theory and then with a new resampling procedure called "reversed jackknifing" that does not require any restrictive distributional assumptions. A Monte Carlo study demonstrates the effectiveness of these procedures. Our methods successfully detect process faults for quadrupole mass spectrometry samples collected from a rapid thermal chemical vapor deposition process     

Magnetism in SiC implanted with high doses of Fe and Mn

High concentrations (0.1–5 at.%) of Mn or Fe were introduced into the near-surface region (≤2000 Å) of 6H-SiC substrates by direct implantation at ～300°C. After annealing at temperatures up to 1000°C, the structural properties were examined by transmission electron microscopy (TEM) and selected-area diffraction pattern (SADP) analysis. The magnetic properties were examined by SQUID magnetometry. While the Mn-implanted samples were paramagnetic over the entire dose range investigated, the Fe-implanted material displayed a ferromagnetic contribution present at <175 K for the highest dose conditions. No secondary phases were detected, at least not to the sensitivity of TEM or SADP.     

Development and characterization of magnetorheological polymer gels

Magnetorheological materials have been used in many applications in recent years. To develop new materials, polyurethane and silicone polymer gels were investigated. Rheology is qualitatively controlled for each system by controlling the concentration of reactants and diluents. The resulting polymers have solid, gel, or liquid states, depending on the crosslinking and dilution. The gels were characterized through kinetic analysis. Differential scanning calorimetry (DSC) was used with analysis methods to find the kinetic properties for diluted and undiluted polyurethane systems. Heat of reaction, order of reaction, preexponential constant, and activation energy were obtained from the experimental DSC data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2733–2742, 2002