Photoelectrochemical reduction of nitrate on p-Si coated with metallic Re thin films

In this study we examined the rhenium electrodeposition process onto p-Si(100) from acidic media. The study was carried out by means of cyclic voltammetry and the potential-steps method from which the corresponding nucleation and growth mechanism were determined. Both methods were performed under illumination using a solar simulator for electron photogeneration. A 3D progressive nucleation, diffusion-controlled growth of rhenium films was found. Likewise, a morphologic analysis was completed for the deposits obtained at different potential values by means of atomic force microscopy. An energetic characterization through capacitance measurements (Mott–Schottky plots and parallel capacitance) of the p-Si/NO₃⁻ and p-Si/Re/NO₃⁻ interfaces was done.The photoelectrochemical reduction of nitrate ions, PERN, on the different p-Si/Re electrode systems synthesized was studied. An overpotential decrease of 0.3 V and a photocurrent increase for the PERN on p-Si(100)/Re electrode systems compared with p-Si(100) and metallic Re was found. Finally, the kinetic parameters of the cathodic reactions in the p-Si and p-Si/Re acidic media were estimated using intensity modulated photocurrent spectroscopy. A brief analysis from this technique was done. According to these results, the p-Si/Re electrode system could be a potential photoelectrocatalyst for the PERN.     

Multiple Objective Genetic Algorithms for Path-planning Optimization in Autonomous Mobile Robots

This paper describes the use of a genetic algorithm (GA) for the problem of offline point-to-point autonomous mobile robot path planning. The problem consists of generating “valid” paths or trajectories, for an Holonomic Robot to use to move from a starting position to a destination across a flat map of a terrain, represented by a two-dimensional grid, with obstacles and dangerous ground that the Robot must evade. This means that the GA optimizes possible paths based on two criteria: length and difficulty. First, we decided to use a conventional GA to evaluate its ability to solve this problem (using only one criteria for optimization). Due to the fact that we also wanted to optimize paths under two criteria or objectives, then we extended the conventional GA to implement the ideas of Pareto optimality, making it a multi-objective genetic algorithm (MOGA). We describe useful performance measures and simulation results of the conventional GA and of the MOGA that show that both types of GAs are effective tools for solving the point-to-point path-planning problem.     

Using Broad Phonetic Group Experts for Improved Speech Recognition

In phoneme recognition experiments, it was found that approximately 75% of misclassified frames were assigned labels within the same broad phonetic group (BPG). While the phoneme can be described as the smallest distinguishable unit of speech, phonemes within BPGs contain very similar characteristics and can be easily confused. However, different BPGs, such as vowels and stops, possess very different spectral and temporal characteristics. In order to accommodate the full range of phonemes, acoustic models of speech recognition systems calculate input features from all frequencies over a large temporal context window. A new phoneme classifier is proposed consisting of a modular arrangement of experts, with one expert assigned to each BPG and focused on discriminating between phonemes within that BPG. Due to the different temporal and spectral structure of each BPG, novel feature sets are extracted using mutual information, to select a relevant time-frequency (TF) feature set for each expert. To construct a phone recognition system, the output of each expert is combined with a baseline classifier under the guidance of a separate BPG detector. Considering phoneme recognition experiments using the TIMIT continuous speech corpus, the proposed architecture afforded significant error rate reductions up to 5% relative     

Communal behaviors and psychological adjustment of family caregivers and persons with spinal cord injury.

Objective: Examined the influence of mutual communal behaviors on the adjustment reported by persons with spinal cord injury (SCI) and their family caregivers. Previous research has found that persons who have a history of mutually communal behaviors in relationships may react differently to relationship changes after an acquired physical disability than dyads with few communal behaviors. Method: Family caregivers and persons with SCI were administered measures of mutual communal behaviors, depression, and life satisfaction. Structural equation modeling was used to test the relations among caregivers' communal behaviors and care recipients' communal behaviors, depression, and life satisfaction. Results: Caregiver and care recipient reports of communal behaviors were not significantly correlated. Significant paths indicated that care recipients' communal behavior scores were positively associated with their life satisfaction, and care recipients' depression was inversely associated with their life satisfaction. Caregivers' communal behavior scores were unrelated to their self-reported adjustment. Conclusions: Caregiver-care recipient dyads may differ in their perceptions of communal behaviors in their relationships. Although care recipient reports of communal behavior may be related to their life satisfaction, communal behaviors may not serve a similar function among caregivers of persons with SCI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluating risk and functioning in persons with serious and persistent mental illness.

The Current Evaluation of Risk and Functioning-Revised (CERF-R), an assessment instrument designed for use with adults with severe and persistent mental illness (SPMI) delineates 18 areas of risk and functioning along with judgments regarding level of care needs. Consensus treatment team ratings were obtained on 736 state hospital patients and 2,607 clients receiving public sector mental health services in the community. Results indicate that the CERF-R exhibits a high level of internal consistency, test-retest, and interrater reliability. Concurrent validity was evident for the functional subscale. The functional and risk items successfully discriminate level of service needs. Factor analysis of the CERF-R is consistent with the three primary reasons persons with SPMI need public mental health services. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An intelligent hybrid approach for industrial quality control combining neural networks, fuzzy logic and fractal theory

The application of type-2 fuzzy logic to the problem of automated quality control in sound speaker manufacturing is presented in this paper. Traditional quality control has been done by manually checking the quality of sound after production. This manual checking of the speakers is time consuming and occasionally was the cause of error in quality evaluation. For this reason, by applying type-2 fuzzy logic, an intelligent system for automated quality control in sound speaker manufacturing is developed. The intelligent system has a type-2 fuzzy rule base containing the knowledge of human experts in quality control. The parameters of the fuzzy system are tuned by applying neural networks using, as training data, a real time series of measured sounds produced by good sound speakers. The fractal dimension is used as a measure of the complexity of the sound signal.     

Assessment as an intervention in the child and family forensic setting.

Before a Children's Court decision is reached, a clinical assessment may be ordered by the court. This assessment often occurs when tension is high for the family and when well-established defenses may falter, and it can provide a prime, critical opportunity to facilitate positive change. Comprehensive psychological assessment at the Children's Court Clinic in Melbourne, Australia, indicates the intervention value of a serious attempt to understand the complexity of the psychological issues facing a child and family. With the aid of illustrative case studies, this article discusses the therapeutic aspects and implications of such assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting adsorption isotherms for aqueous organic micropollutants from activated carbon and pollutant properties

A method based on the Polanyi-Dubinin-Manes (PDM) model is presented to predict adsorption isotherms of aqueous organic contaminants on activated carbons. It was assumed that trace organic compound adsorption from aqueous solution is primarily controlled by nonspecific dispersive interactions while water adsorption is controlled by specific interactions with oxygen-containing functional groups on the activated carbon surface. Coefficients describing the affinity of water for the activated carbon surface were derived from aqueous-phase methyl tertiary-butyl ether (MTBE) and trichloroethene (TCE) adsorption isotherm data that were collected with 12 well-characterized activated carbons. Over the range of oxygen contents covered by the adsorbents (approximately 0.8-10 mmol O/g dry, ash-free activated carbon), a linear relationship between water affinity coefficients and adsorbent oxygen content was obtained. Incorporating water affinity coefficients calculated from the developed relationship into the PDM model, isotherm predictions resulted that agreed well with experimental data for three adsorbents and two adsorbates [tetrachloroethene (PCE), cis-1,2-dichloroethene (DCE)] that were not used to calibrate the model.     

Surface charge heterogeneities measured by atomic force microscopy

Unfavorable aggregation and deposition of colloidal particles in natural and engineered systems is still a subject of debate. Complicating factors such as surface roughness, secondary minimum aggregation, and the nature of discrete surface charge and surface potential make it difficult to attribute a specific cause to these phenomena. The presence of surface charge heterogeneity and its influence on interaction forces, which are responsible for aggregation and deposition, are studied in this work through the application of atomic force microscopy (AFM). Force-volume-mode AFM was used to map interaction forces on a surface and relate them to surface charge heterogeneities. The experimental system consisted of a silica plate and a standard silicon nitride AFM tip. Copper ions were used for sorption on the silica surface in order to modify the surface charge and cause charge reversal. Different concentrations of copper ions were selected to identify conditions of partial coverage of the silica surface. The pH and ionic strength of the solutions were varied, and the extension of the surface charge modification and its influence on the resulting interaction forces were monitored via AFM force measurements. Depending on the pH and ionic strength, the interaction force was found to change at certain regions on the surface from attraction to either weak or strong repulsion. Force imaging allowed the visual localization of zones of strong repulsive interaction that diminished in size with increasing ionic strength. X-ray photoelectron spectroscopy analysis was used to confirm the presence of copper on the surface. Local charge differences on a surface result in local differences in surface forces, not only in magnitude but also in direction. This behavior may explain the aggregation, deposition, and transport of colloidal particles under unfavorable chemical conditions.