Diffused junction p+−n solar cells in bulk GaAs—II: Device characterization and modelling

The photovoltaic characteristics of p⁺-n junction solar cells fabricated on bulk GaAs by an open tube diffusion technique are presented in detail. Quantum efficiency measurements were analyzed and compared to computer simulations of the cell structure in order to determine material parameters such as diffusion length, surface recombination velocity and junction depth. From the results obtained it is projected that proper optimization of the cell parameters can increase the efficiency of the cells to close to 20%.     

Effect of counselor technique on Mexican-American and Anglo-American self-disclosure and counselor perception.

A counseling analog study examined the effects of 3 interviewing techniques on 124 Mexican-American and Anglo-American undergraduates' willingness to self-disclose and perception of the counselor. The interviewing techniques manipulated were probing, disclosing, and reflecting. No differences across intervention techniques were found on the total scores of the disclosure questionnaire. Females disclosed less than males on the Body subscale of the disclosure questionnaire, but no ethnic differences in willingness to disclose were found. There were no differences in scores on the Barrett-Lennard Relationship Inventory (BLRI). Significantly more Ss in the probing than the reflecting condition indicated they would return for a 2nd interview. A positive correlation between willingness to disclose and scores on the BLRI was found. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

PhD theses in Spain: A gender study covering the years 1990–2004

In this study we analyse gender equality in the preparation, supervision and defence of PhD theses in Spain in the period 1990–2004. The results indicate a tendency towards greater equality in the number of men and women successfully completing doctoral studies. However, the gender imbalance among thesis supervisors and on thesis assessment boards is more apparent, with a predominance of male academics. Moreover, the gender of the PhD student is clearly related to the gender of the supervisor, and both are related to the gender of the members of the assessment boards of PhD theses in Spain.     

Fatigue crack growth and crack closure in an AlMgSi alloy

This study reports an experimental investigation of fatigue crack propagation in AlMgSi1-T6 aluminium alloy using both constant and variable load amplitudes. Crack closure was monitored in all tests by the compliance technique using a pin microgauge. For the constant amplitude tests four different stress ratios were analysed. The crack closure parameter U was calculated and related with Δ K and the stress ratio, R . The threshold of the stress intensity factor range, Δ K _th , was also obtained. Fatigue crack propagation tests with single tensile peak overloads have been performed at constant load amplitude conditions. The observed transient post overload behaviour is discussed in terms of the overload ratio, Δ K baseline level and R . The crack closure parameter U trends are compared with the crack growth transients. Experimental support is given for the hypothesis that crack closure is the main factor determining the transient crack growth behaviour following overloads on AlMgSi1-T6 alloy for plane stress conditions.     

Engineering Education Research: Discipline,Community, or Field?

Engineering education research has experienced a notable scale‐up in recent years through the development of departments and degree programs, high‐profile publication outlets, research agendas, and meetings. We begin by reviewing these developments, contextualizing them historically, and clarifying some relevant terminology. We then use observational data collected at the 2007 inaugural International Conference on Research in Engineering Education (ICREE) to examine how engineering education is variously conceptualized as a discipline, community of practice, and/or field. We also examine how ICREE participants engaged with questions about the infrastructure and major goals of engineering education research. Our data reveals both an overall lack of clarity and continued sense of ambiguity about the identity and status of engineering education research. We conclude by recommending that participants and stakeholders work to clarify the goals and objectives of engineering education research, especially to inform the continued development of the field's identity and supporting infrastructures.     

Time Evolution of an AMD-Affected River Chemical Makeup

Acid mine drainage is the main problem encountered by sulphide mining operations, not only because of its ecological aspects, but also because, once it appears, it is very difficult to remediate both technologically and economically. This paper characterises the response of an acid mine drainage-affected channel in the Iberian Pyrite Belt (Southwest of the Iberian Peninsula, Huelva, Spain) to the stimulus of rainfall in its drainage basin by studying the cause–effect relationships between sulphate, iron, copper, zinc, manganese, arsenic and cadmium concentrations in water samples taken at three points and rainfall in the zone.     

Microbiological quality of natural waters

Several aspects of the microbiological quality of natural waters, especially recreational waters, have been reviewed. The importance of the water as a vehicle and/or a reservoir of human pathogenic microorganisms is also discussed. In addition, the concepts, types and techniques of microbial indicator and index microorganisms are established. The most important differences between faecal streptococci and enterococci have been discussed, defining the concept and species included. In addition, we have revised the main alternative indicators used to measure the water quality.     

Diffused junction p+−n solar cells in bulk GaAs—I: Fabrication and cell performance

This paper describes the fabrication of solar cells made by a simple open tube p⁺-diffusion into bulk n-GaAs. In addition, cell performance is provided as an indicator of the quality of bulk GaAs for this application. Initial results using this technique (12.2% efficiency at AM1 for 0.5 cm² cells) are promising, and indicate directions for materials improvement. It is shown that the introduction of the diffusant (zinc) with point defects significantly affects the material properties and results in an increase in current capability.