Characterization of piezocrystals for practical configurations with temperature- and pressure-dependent electrical impedance spectroscopy

Piezoelectric single crystal materials such as (x)Pb(Mg(1/3)Nb(2/3))O(3-)(1-x)PbTiO(3) (PMN-PT) have, by some measures, significantly better performance than established piezoelectric ceramics for ultrasound applications. However, they are also subject to phase transitions affecting their behavior at temperatures and pressures encountered in underwater sonar and actuator applications and in non-destructive testing at elevated temperatures. Materials with modified compositions to reduce these problems are now under development, but application-oriented characterization techniques need further attention. Characterization with temperature variation has been reported extensively, but the range of parameters measured is often limited and the effects of pressure variation have received almost no attention. Furthermore, variation in properties between samples is now rarely reported. The focus of this paper is an experimental system set up with commercially available equipment and software to carry out characterization of piezoelectric single crystals with variation in temperature, pressure, and electrical bias fields found in typical practical use. We illustrate its use with data from bulk thickness-mode PMN-29%PT samples, demonstrating variation among nominally identical samples and showing not only the commonly reported changes in permittivity with temperature for bulk material but also significant and complicated changes with pressure and bias field and additional ultrasonic modes which are attributed to material phase changes. The insight this provides may allow the transducer engineer to accelerate new material adoption in devices.     

Balancing Multiple Criteria Incorporating Cost using Pareto Front Optimization for Split‐Plot Designed Experiments

Finding a D‐optimal design for a split‐plot experiment requires knowledge of the relative size of the whole plot (WP) and sub‐plot error variances. Since this information is typically not known a priori, we propose an optimization strategy based on balancing performance across a range of plausible variance ratios. This approach provides protection against selecting a design which could be sub‐optimal if a single initial guess is incorrect. In addition, options for incorporating experimental cost into design selection are explored. The method uses Pareto front multiple criteria optimization to balance these objectives and allows the experimenter to understand the trade‐offs between several design choices and select one that best suits the goals of the experiment. We present new algorithms for populating the Pareto front for the split‐plot situation when the number of WPs is either fixed or flexible. We illustrate the method with a case study and demonstrate how considering robustness across variance ratios offers improved performance. The Pareto approach identifies multiple promising designs, and allows the experimenter to understand trade‐offs between alternatives and examining their robustness to different ways of combining the objectives. New graphical summaries for up to four criteria are developed to help guide improved decision‐making. Copyright © 2012 John Wiley & Sons, Ltd.     

New charge-transfer salts for reversible resistive memory switching

We found novel organic charge-transfer salts that exhibit reversible resistive memory switching phenomena. Homogeneous layers of these complexes can be easily fabricated using solution processing. The copper-2,3-dichloro-5,6-dicyano-p-benzoquinone complex was investigated in more detail. Devices made of this complex can be reversibly switched between a high and a low resistance state by applying voltage pulses as short as 1 micros. The memory states remain stable for more than 15 h without an electricity source.     

Ex-offenders reentering the workforce.

Approximately 650,000 individuals will be released from incarceration in state and federal prisons this year. However, little is known about the challenges ex-offenders face when they endeavor to reenter the workforce. The authors used consensual qualitative research methods to analyze data from 2 focus groups: one for male (n=6) and another for female (n=9) nonviolent felony offenders, all of whom were receiving services at day reporting centers, which offer a nonresidential form of community corrections. Attendees discussed their reentry experiences, and 11 domains were identified, encompassing ex-offenders' needs for education, training, and practical assistance; challenges in obtaining and maintaining a job; and available support, including personal networks and resources from the correctional system. Findings suggest that counseling professionals should attend to ex-offenders' social networks, including social aspects of the workplace, as such networks can offer support or represent a liability for individuals in transition. Substance abuse issues impact ex-offenders' social viability as well as their career-related reentry attempts. Finally, career development practitioners should understand the internal and external impacts of the stigma associated with incarceration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Le questionnaire d'évaluation des relations parent/enfant (QéRPE): Une validation fran?aise de l'Egna Minnen Betr?ffende Uppfostran (EMBU).

Parents influence a child's development and his or her success in academic, sports or musical matters. Their support is essential for success. However, some of their behaviours may also have a negative impact. We need to better define parent/child relationships and their influence on the success and well-being of the child. Questionnaires are helpful in this respect, but few valid tools in French exist. Those available do not focus on evaluating dimensions central to child development. This article is aimed at validating the French translation of the EMBU questionnaire (Egna Minnen Betr?ffende Uppfostran, Perris, Jacobsson, Lindstr??m, von Knorring & Perris, 1980), the Questionnaire d'évaluation des relations parents/enfant (QéRPE), Questionnaire to Evaluate Parent/Child Relationships. It assesses the levels of parental support, overprotection and rejection experienced by children. We applied it to relationships between parents and sports-lovers. We tested the factorial structure (exploratory and confirmatory analyses) and the internal consistency of the QéRPE, and conducted external validation. Our results demonstrated that the psychometric qualities of the QéRPE are very acceptable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

WASTE MINIMIZATION IN BATCH VESSEL CLEANING

Although the cleaning of processing vessels has always been a significant source of waste, only recently have fundamental studies been undertaken to understand the cleaning process. The study described here began with a review of the literature on industrial cleaning practices. The literature was found to be mainly empirical. In order to provide a practical direction for research into the cleaning process, observations were made of a commercial batch processing facility. Based on these observations, short-term process improvements are suggested, and a new area for fundamental research is identified. @KEYWORDS Waste minimization Reflux cleaning Reactor Batch vessel.     

View Definition and Positioning in DOOD Systems

Because there is no difference between derivation rules and view definitions, DOOD systems are the best candidates to support an object-oriented view mechanism. Yet, to combine expressive power (i.e. no restriction on queries defining views), reusability and modeling accuracy (i.e. insertion of views into the generalization hierarchy), and consistency (stability in oid generation) is still an open challenging domain for OO research. This paper is a contribution to improve existing solutions while simplifying the task of users in the view definition process.     

DSP Implementation of Antenna Array Algorithms for OFDM-Based Wireless LAN

Motivated by the theoretical results on multi-antenna signal processing techniques promising substantial performance gains, a feasible reconfigurable hardware architecture for OFDM-based Wireless LANs is presented in this paper. The ultimate objective of the platform is to support single-antenna links, as well as antenna arrays at the receiver and/or at the transmitter, taking into account the limitations caused by a real-time implementation. After a brief overview of the implemented multi-antenna algorithms, we present the hardware platform that has been built based on both fixed point and floating point DSPs from Texas Instruments, together with the evaluation of the complexity associated to the operations, and their scheduling. The performance indicates that a multi-antenna architecture supporting up to four antennas at the receiver side might accomplish the real-time requirements.     

Selective sparing after lesions of visual cortex in newborn kittens.

Previous findings are discordant regarding the effects of perinatal lesions of Cortical Areas 17 and 18 on visual discrimination learning in cats. Three potential determinants of such sparing were investigated: age at lesion (4 or 181 days), age at testing (3 or 9 months), and stimulus complexity. Age at testing was not significant, but performance varied with stimulus complexity and cortical damage, and there was an interaction between stimulus complexity and age at lesion. Both operated groups were transiently impaired in discriminating objects and subsequently learned to discriminate simple 2-dimensional patterns as well as done by controls, but the lesion groups were permanently impaired in discriminating similiar patterns circumscribed by irrelevant lines. The age-at-lesion groups differed, however, in discriminating patterns masked by superimposed lines. The group lesioned at 181 days was severely impaired at both acquisition and subsequent intercurrent performance; the group lesioned at 4 days was impaired only at intercurrent performance. This study suggests that sparing after early postnatal damage of Areas 17 and 18 occurs only under limited circumstances. (PsycINFO Database Record (c) 2010 APA, all rights reserved)