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Showing papers by "Concordia University published in 2004"


Journal ArticleDOI
TL;DR: Detailed principles for making design choices during the process of selecting appropriate experts for the Delphi study are given and suggestions for theoretical applications are made.

3,510 citations


Journal ArticleDOI
TL;DR: A meta-analysis of the comparative distance education literature between 1985 and 2002 was conducted by as discussed by the authors, where 232 studies containing 688 independent achievement, attitude, and retention outcomes were analyzed.
Abstract: A meta-analysis of the comparative distance education (DE) literature between 1985 and 2002 was conducted. In total, 232 studies containing 688 independent achievement, attitude, and retention outcomes were analyzed. Overall results indicated effect sizes of essentially zero on all three measures and wide variability. This suggests that many applications of DE outperform their classroom counterparts and that many perform more poorly. Dividing achievement outcomes into synchronous and asynchronous forms of DE produced a somewhat different impression. In general, mean achievement effect sizes for synchronous applications favored classroom instruction, while effect sizes for asynchronous applications favored DE. However, significant heterogeneity remained in each subset.

1,577 citations


BookDOI
01 Jan 2004
TL;DR: Beyond Significance Testing as mentioned in this paper provides integrative and clear presentations about the limitations of statistical tests and reviews alternative methods of data analysis, such as effect size estimation (at both the group and case levels) and interval estimation (i.e., confidence intervals).
Abstract: Practices of data analysis in psychology and related disciplines are changing. This is evident in the longstanding controversy about statistical tests in the behavioral sciences and the increasing number of journals requiring effect size information. Beyond Significance Testing offers integrative and clear presentations about the limitations of statistical tests and reviews alternative methods of data analysis, such as effect size estimation (at both the group and case levels) and interval estimation (i.e., confidence intervals). Written in a clear and accessible style, the book is intended for applied researchers and students who may not have strong quantitative backgrounds. Readers will learn how to measure effect size on continuous or dichotomous outcomes in comparative studies with independent or dependent samples. They will also learn how to calculate and correctly interpret confidence intervals for effect sizes. Numerous research examples from a wide range of areas illustrate the application of these principles and how to estimate substantive significance instead of just statistical significance.

924 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined the relationship between employee personality and psychological contract type, perceptions of contract breach, and feelings of contract violation, and found that personality characteristics were positively associated with contract violation.
Abstract: This research examined the relationship between employee personality and psychological contract type, perceptions of contract breach, and feelings of contract violation. In general, personality cha...

764 citations


Journal ArticleDOI
TL;DR: The authors investigated the role of context of learning in second language (L2) acquisition and found that learners in the SA context made greater gains, both in terms of temporal and hesitation phenomena and in oral proficiency as measured by the oral proficiency interview (OPI).
Abstract: This study investigates the role of context of learning in second language (L2) acquisition. Participants were 40 native speakers of English studying Spanish for one semester in one of two different learning contexts—a formal classroom at a home university (AH) and a study abroad (SA) setting. The research looks at various indexes of oral performance gains—particularly gains in oral fluency as measured by temporal and hesitation phenomena and gains in oral proficiency based on the Oral Proficiency Interview (OPI). The study also examines the relation these oral gains bore to L2-specific cognitive measures of speed of lexical access (word recognition), efficiency (automaticity) of lexical access, and speed and efficiency of attention control hypothesized to underlie oral performance. The learners also provided estimates of the number of hours they spent in extracurricular language-contact activities. The results show that in some respects learners in the SA context made greater gains, both in terms of temporal and hesitation phenomena and in oral proficiency as measured by the OPI, than learners in the AH context. There were also, however, significant interaction effects and correlational patterns indicating complex relationships between oral proficiency, cognitive abilities, and language contact. The results demonstrate the importance of the dynamic interactions that exist among oral, cognitive, and contextual variables. Such interactions may help explain the enormous individual variation one sees in learning outcomes, and they underscore the importance of studying such variables together rather than in isolation.This research was funded in part by a grant to Barbara F. Freed from the Council on International Educational Exchange, New York, in part by a grant from the Natural Sciences and Engineering Research Council of Canada to Norman Segalowitz, and in part by a grant from the Dean's Office, Faculty of Arts and Science at Concordia University, to Segalowitz. The authors wish to thank Joe Collentine, Manuel Diaz-Campos, and Barbara Lafford, who are members of the research team involved in the larger project of which this study is one part. A special note of thanks is due to Nicole Lazar, who is also a member of the research team, for her invaluable statistical advice. Finally, the authors would like to thank Conchita Bueno, Hazel Casas, Elizabeth Gatbonton, Randall Halter, Guy Lacroix, Anne-Marie Linnen, Magnolia Negrete, Irene O'Brien, Laura Renteria-Diaz, Marlene Taube, and Naomi Yamasaki, who helped during various phases of this project.

658 citations


Journal ArticleDOI
TL;DR: The research on subtypes of OCD is reviewed, focusing on subtype schemes based upon overt symptom presentation and neuropsychological profiles, and research pertinent to alternative subtyping schemes are reviewed, both conceptually and methodologically.

555 citations


Journal ArticleDOI
TL;DR: A robust adaptive control scheme is developed without constructing the dead-zone inverse, which ensures global stability of the adaptive system and achieves desired tracking precision.

513 citations


Journal ArticleDOI
TL;DR: The authors compared the acquisition of various dimensions of fluency by 28 students of French studying in three different learning contexts: formal language classrooms in an at home (AH) institution, an intensive summer immersion (IM) program, and a study abroad (SA) setting.
Abstract: We compared the acquisition of various dimensions of fluency by 28 students of French studying in three different learning contexts: formal language classrooms in an at home (AH) institution, an intensive summer immersion (IM) program, and a study abroad (SA) setting. For the purpose of oral data collection, students participated in oral interviews (similar to the Oral Proficiency Interview) at the beginning and the end of the semester and provided information regarding language use and interactions. Analyses included comparisons of gain scores as a function of the learning context and as a function of the time reported using French outside of class. The main findings that reached statistical significance include: (a) The IM group made significant gains in oral performance in terms of the total number of words spoken, in length of the longest turn, in rate of speech, and in speech fluidity based on a composite of fluidity measures. When compared to the AH group, the SA group made statistically significant gains only in terms of speech fluidity but fewer gains than the IM group. The AH group made no significant gains. (b) The IM students reported that they spoke and wrote French significantly more hours per week than the other two groups. The SA group reported using English more than French (although the difference was not statistically significant) and reported using significantly more English in out-of-class activities than the IM group. (c) Multiple regression analyses revealed that reported hours per week spent writing outside of class was significantly associated with oral fluidity gains.Appreciation is expressed to a number of organizations and individuals without whom this project would not have been brought to completion. Contributions of funding, technical support and expertise, or both are acknowledged from: ACTFL (Elvira Spender and Robert Vicars); Carnegie Mellon University (The Office of the President and Bonnie Youngs in the Department of Modern Languages); The Natural Sciences and Engineering Research Council of Canada; Concordia University (International Initiatives Research Program, Office of the Dean of the Faculty of Arts and Science); Concordia University (Randall Halter, Eric Buisson, Christine Brassard, Eowyn Crisfield, Nilmini de Silva, Sarah Frenkiel, and Heather Wilcox); Middlebury College (Clara Yu, Michael Katz, Beth Karnes, Kara Gennarelli, Paula Schwartz, Carol Rifelj, Jean-Claude Redonnet, Guy Spielmann, Beverly Keim, Anna Sun, and Alex Chapin). The authors also thank Nicole Lazar for her helpful statistical advice.

499 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the grain boundary serrations meet across the elongated thinned grains thus pinching them off into almost equiaxed grains containing a substructure, thus geometric DRX.
Abstract: Although hot working had been defined as deformation above the recrystallization temperature (determined after cold working), it was only about 1965 that dynamic recrystallization (DRX) was confirmed to be occurring during the deformation; two decades were required to clarify the similarities to, and the differences from, static recrystallization. In classical discontinuous DRX in Cu, Ni, and γ-Fe, successive necklaces of new grains cause work softening; however in steady-state, the nuclei are uniformly distributed as reestablished dislocation structure limits growth. In high recovery metals at high strains, the grain boundary (GB) serrations meet across the elongated thinned grains thus pinching them off into almost equiaxed grains containing a substructure, thus geometric DRX.

372 citations


Journal ArticleDOI
TL;DR: Soy hydrolysate and the soy-fermented foods, natto and tempeh, were dephosphorylated, deglycosylated and digested with a variety of endoproteases to generate oligopeptides, which demonstrated a range of biological activities – angiotensin converting enzyme (ACE) inhibitory, anti-thrombotic, surface tension and antioxidant properties.

368 citations


Journal ArticleDOI
TL;DR: In this article, the authors assess how management's perceptions regarding certain aspects of environmental reporting relate to the firm's actual reporting strategy and propose a model where a firm's environmental disclosure is conditional upon executive assessments of corporate concerns.
Abstract: This paper's purpose is to assess how management's perceptions regarding certain aspects of environmental reporting relate to the firm's actual reporting strategy. Toward that end, we propose a model where a firm's environmental disclosure is conditional upon executive assessments of corporate concerns. The study relies on a survey that was sent to environmental management executives from European and North American multinational firms enquiring about the determinants of corporate environmental disclosure. Responses from these executives were then contrasted with their firms' actual environmental reporting practices, which was measured using a comprehensive multi-criteria grid. Results show that there is a relationship between environmental managers' attitudes toward various stakeholder groups and how those managers respond to the stakeholders via the decision to disclose and the actual disclosures made. Our model provides a perspective as to how a firm responds to the numerous stakeholders to whom it must be accountable. This accountability in turn relates to how the company communicates its actions to society in order to achieve or maintain its social legitimacy.

Journal ArticleDOI
TL;DR: In this article, the major imperative emerges that the born global must utilize large channels provided by MNCs, networks, and/or the Internet to receive substantial revenues and cash flow rapidly.

Book
01 Nov 2004
TL;DR: In this article, the authors introduce 2-D wavelets via 1-D continuous wavelet transforms, which offer a number of advantages over discrete wavelet transform for analysis of real-time signals in such areas as medical imaging, fluid dynamics, shape recognition, image enhancement and target tracking.
Abstract: Two-dimensional wavelets offer a number of advantages over discrete wavelet transforms when processing rapidly varying functions and signals. In particular, they offer benefits for real-time applications such as medical imaging, fluid dynamics, shape recognition, image enhancement and target tracking. This book introduces 2-D wavelets via 1-D continuous wavelet transforms. The authors then describe the underlying mathematics before progressing to more advanced topics such as matrix geometry of wavelet analysis and three-dimensional wavelets. Practical applications and illustrative examples are employed extensively throughout, ensuring the book's value to engineers, physicists and mathematicians. Two-dimensional wavelets offer a number of advantages over discrete wavelet transforms, in particular, for analysis of real-time signals in such areas as medical imaging, fluid dynamics, shape recognition, image enhancement and target tracking.

Posted Content
TL;DR: In this article, the authors examined the effects of the multiple dimensions of intangibility on the various types of risk and found that, of the three dimensions, physical Intangibility was the least correlated to the consumers' perception of risk in most situations, whereas mentalIntangibility and generality had a great impact on most dimensions of perceived risk.
Abstract: Studies have found that product intangibility increases consumers’ perception of risk. However, most of these studies measured the intangibility and perceived risk constructs unidimensionally. The primary objective of this article is to examine the effects of the multiple dimensions of intangibility on the various types of risk. An empirical investigation revealed that, of the three intangibility dimensions, physical intangibility was the least correlated to the consumers’ perception of risk in most situations, whereas mental intangibility and generality had a great impact on most dimensions of perceived risk. However, there were variations in the strength of the relationships between the intangibility dimensions and the risk dimensions when contrasting goods and services, generic products and brands, and online and offline purchase contexts. Theoretical and practical contributions to the service marketing literature are discussed.

Journal ArticleDOI
TL;DR: The role of various mechanoreceptors in the human hand are discussed in relation to the stimuli like force, position, softness, and surface texture and the necessary engineering features of an artificial tactile sensor are reviewed.
Abstract: In this paper, we examine the most important features of human skin tactile properties with special emphasis on the characteristics which are vital in the design of artificial systems. Contrary to the visual and auditory senses, the touch signal is not a well-defined quantity. As a result, the researchers of this field are still dealing with the basics of collecting the most relevant data. Following this, mimicking the sense of touch by producing artificial tactile skin is a challenging process. Although the sense of touch is widely distributed all over the human body, the tactile perception in the human hand is of great importance in terms of surgical and medical robotics applications. In this study, the role of various mechanoreceptors in the human hand, such as, RA, SA I, SA II, and PC units are discussed in relation to the stimuli like force, position, softness, and surface texture. Taking human hand as a suitable tactile model, the necessary engineering features of an artificial tactile sensor, such as, spatial and temporal resolutions, force sensitivity, and linearity, are being reviewed. In this work, we also report on the current and possible future applications of tactile sensors in various surgical procedures.

Journal ArticleDOI
TL;DR: This paper examined the role that champions play in the generation and promotion of ideas in the innovation process, and considered the influence of flexible role orientation and contextual knowledge in this process, finding that the role of role orientation was positively related to idea generation.
Abstract: This study examined the role that champions play in the generation and promotion of ideas in the innovation process, and considered the influence of flexible role orientation and contextual knowledge in this process. Content analysis of interview transcripts from 19 matched pairs of champions and nonchampions revealed that flexible role orientation was positively related to idea generation, and contextual knowledge was positively related to packaging ideas for promotion. Idea generation was positively related to promoting ideas through informal and formal channels. Finally, in comparison with nonchampions, champions demonstrated more enthusiastic support for new ideas, tied the innovation to a greater variety of positive organizational outcomes, and used informal selling processes more often during idea promotion.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the effects of the multiple dimensions of intangibility on the various types of risk and found that, of the three dimensions, physical Intangibility was the least correlated to the consumers' perception of risk in most situations, whereas mentalIntangibility and generality had a great impact on most dimensions of perceived risk.
Abstract: Studies have found that product intangibility increases consumers’ perception of risk. However, most of these studies measured the intangibility and perceived risk constructs unidimensionally. The primary objective of this article is to examine the effects of the multiple dimensions of intangibility on the various types of risk. An empirical investigation revealed that, of the three intangibility dimensions, physical intangibility was the least correlated to the consumers’ perception of risk in most situations, whereas mental intangibility and generality had a great impact on most dimensions of perceived risk. However, there were variations in the strength of the relationships between the intangibility dimensions and the risk dimensions when contrasting goods and services, generic products and brands, and online and offline purchase contexts. Theoretical and practical contributions to the service marketing literature are discussed.

Journal ArticleDOI
O. Schwelb1
TL;DR: In this article, the transmission, group delay time and quadratic dispersion properties of the four basic building blocs of optical filters built using ring resonators are described, and explicit expressions to compute the complex amplitude of the circulating wave in the ring, the Q factor, the finesse and the insertion loss are also given.
Abstract: This tutorial describes the transmission, group delay time and quadratic dispersion properties of the four basic building blocs of optical filters built using ring resonators. These building blocs are single-ring resonators in either two-port (all-pass) or four-port (add/drop filter) configuration. The effect of waveguide and coupler loss is included throughout. Explicit expressions to compute the complex amplitude of the circulating wave in the ring, the Q factor, the finesse and the insertion loss are also given. Attention is drawn to the similarities between the ring resonator the Fabry-Pe/spl acute/rot resonator and the Gires-Tournois interferometer. Material properties and fabrication technology are not reviewed.

Journal ArticleDOI
TL;DR: This article examined the influence of culture on the measurement of service quality and satisfaction in dentists' office settings and found that Japanese consumers are more conservative in their evaluations of superior service but are less critical (or more forgiving) of inferior service.
Abstract: The authors examine the influence of culture on the measurement of service quality and satisfaction in dentists’ office settings. Respondents from the United States, Canada, and Japan participated in a 2 × 2 factorial experiment in which the authors manipulated both expectations (high/low) and service performance (high/low) in a series of scenarios. With partial metric invariance, latent mean comparisons revealed that regardless of expectations, Japanese respondents reported lower quality perceptions and satisfaction ratings when performance was high and higher satisfaction ratings when performance was low than did their U.S. and Canadian counterparts. Thus, there is some evidence that Japanese consumers are more conservative in their evaluations of superior service but are less critical (or more forgiving) of inferior service. The authors also discuss managerial implications and future research directions.

Journal ArticleDOI
TL;DR: A model of the ways in which dyadic interactions between employees who occupy 1 of 4 archetypal social roles in organizations can lead to either episodic or institutionalized patterns of victimization is proposed.
Abstract: This article proposes a model of the ways in which dyadic interactions between employees who occupy 1 of 4 archetypal social roles in organizations can lead to either episodic or institutionalized patterns of victimization. The model shows how the occurrence of victimization involving these 4 role types is influenced by organizational variables such as power differences, culture, and access to social capital. The model integrates behavioral and social structural antecedents of victimization to develop a relational perspective on the dynamics of harmful behavior in the workplace.

Journal ArticleDOI
22 Jan 2004-Nature
TL;DR: St isotopic analyses to graphitic black carbon samples isolated from pre-industrial marine and terrestrial sediments find that this material is terrestrially derived and almost entirely depleted of radiocarbon, suggesting that it is graphite weathered from rocks, rather than a combustion product.
Abstract: Marine sediments act as the ultimate sink for organic carbon, sequestering otherwise rapidly cycling carbon for geologic timescales. Sedimentary organic carbon burial appears to be controlled by oxygen exposure time in situ, and much research has focused on understanding the mechanisms of preservation of organic carbon. In this context, combustion-derived black carbon has received attention as a form of refractory organic carbon that may be preferentially preserved in soils and sediments. However, little is understood about the environmental roles, transport and distribution of black carbon. Here we apply isotopic analyses to graphitic black carbon samples isolated from pre-industrial marine and terrestrial sediments. We find that this material is terrestrially derived and almost entirely depleted of radiocarbon, suggesting that it is graphite weathered from rocks, rather than a combustion product. The widespread presence of fossil graphitic black carbon in sediments has therefore probably led to significant overestimates of burial of combustion-derived black carbon in marine sediments. It could be responsible for biasing radiocarbon dating of sedimentary organic carbon, and also reveals a closed loop in the carbon cycle. Depending on its susceptibility to oxidation, this recycled carbon may be locked away from the biologically mediated carbon cycle for many geologic cycles.


Journal ArticleDOI
TL;DR: It is proposed that satellite cells can be induced to re‐enter the cell growth cycle after a single bout of unaccustomed high intensity exercise, however, a one bout of exercise is not sufficient for the satellite cell to undergo terminal differentiation.
Abstract: No studies to date have reported activation of satellite cells in vivo in human muscle after a single bout of high intensity exercise. In this investigation, eight individuals performed a single bout of high intensity exercise with one leg, the contralateral leg being the control. A significant increase in mononuclear cells staining for the neural cell adhesion molecule (N-CAM) and fetal antigen 1 (FA1) were observed within the exercised human vastus lateralis muscle on days 4 and 8 post exercise. In addition, a significant increase in the concentration of the FA1 protein was determined in intramuscular dialysate samples taken from the vastus lateralis muscle of the exercising leg (day 0: 1.89 +/- 0.82 ng ml(-1); day 2: 1.68 +/- 0.37 ng ml(-1); day 4: 3.26 +/- 1.29 ng ml(-1), P < 0.05 versus basal; day 8: 4.68 +/- 2.06 ng ml(-1), P < 0.05 versus basal and control). No change was noted in the control leg. Despite this increase in N-CAM- and FA1-positive mononuclear cells, an increased expression of myogenin and the neonatal isoform of the myosin heavy chain (MHCn) was not observed. Interestingly, myofibre lesions resulting from extensive damage to the proteins within the myofibre, particularly desmin or dystrophin, were not observed, and hence did not appear to induce the expression of either N-CAM or FA1. We therefore propose that satellite cells can be induced to re-enter the cell growth cycle after a single bout of unaccustomed high intensity exercise. However, a single bout of exercise is not sufficient for the satellite cell to undergo terminal differentiation.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the strength and specificity of the relationship between intolerance of uncertainty (IU) and worry with regards to depression in a nonclinical sample, and found that worry was more highly and specifically related to IU than to dysfunctional attitudes (a cognitive process involved in depression).
Abstract: This study examined the strength and specificity of the relationship between intolerance of uncertainty (IU) and worry with regards to depression in a nonclinical sample. The hypotheses were the following: (1) IU would be more highly and specifically related to worry than to depression; and (2) worry would be more highly and specifically related to IU than to dysfunctional attitudes (a cognitive process involved in depression). Two-hundred and forty (240) undergraduate students completed self-report questionnaires that assessed worry, intolerance of uncertainty, depression, and dysfunctional attitudes. Both hypotheses were confirmed: IU was more highly (although not significantly) and specifically related to worry than to depression; and worry was more highly and specifically related to IU than to dysfunctional attitudes. The findings are discussed in terms of their theoretical and clinical implications.

Journal ArticleDOI
TL;DR: This review discusses recent conceptual models and findings from longitudinal studies concerning the intergenerational transfer of psychosocial risk, including interGenerational continuity, and the processes whereby a generation of parents may place their offspring at elevated risk for social, behavioral, and health problems.
Abstract: The recurrence of social, behavioral, and health problems in successive generations of families is a prevalent theme in both the scientific and popular literatures. This review discusses recent conceptual models and findings from longitudinal studies concerning the intergenerational transfer of psychosocial risk, including intergenerational continuity, and the processes whereby a generation of parents may place their offspring at elevated risk for social, behavioral, and health problems. Key findings include the mediational effects of parenting and environmental factors in the transfer of risk. In both girls and boys, childhood aggression and antisocial behavior appear to predict long-term trajectories that place offspring at risk. Sequelae of childhood aggression that may threaten the well-being of offspring include school failure, adolescent risk-taking behavior, early and single parenthood, and family poverty. These childhood and adolescent behavioral styles also predict harsh, aggressive, neglectful, and unstimulating parenting behavior toward offspring. Buffering factors within at-risk families include maternal educational attainment and constructive parenting practices (e.g., emotional warmth, consistent disciplinary practices, and cognitive scaffolding). These findings highlight the potential application and relevance of intergenerational studies for social, educational, and health policy.

Journal ArticleDOI
01 Jun 2004
TL;DR: A new technique for facial expression recognition is proposed, which uses the two-dimensional DCT over the entire face image as a feature detector and a constructive one-hidden-layer feedforward neural network as a facial expression classifier and the input-side weights of the constructed network are reduced by approximately 30% using the pruning method.
Abstract: A new technique for facial expression recognition is proposed, which uses the two-dimensional (2D) discrete cosine transform (DCT) over the entire face image as a feature detector and a constructive one-hidden-layer feedforward neural network as a facial expression classifier. An input-side pruning technique, proposed previously by the authors, is also incorporated into the constructive learning process to reduce the network size without sacrificing the performance of the resulting network. The proposed technique is applied to a database consisting of images of 60 men, each having five facial expression images (neutral, smile, anger, sadness, and surprise). Images of 40 men are used for network training, and the remaining images of 20 men are used for generalization and testing. Confusion matrices calculated in both network training and generalization for four facial expressions (smile, anger, sadness, and surprise) are used to evaluate the performance of the trained network. It is demonstrated that the best recognition rates are 100% and 93.75% (without rejection), for the training and generalizing images, respectively. Furthermore, the input-side weights of the constructed network are reduced by approximately 30% using our pruning method. In comparison with the fixed structure back propagation-based recognition methods in the literature, the proposed technique constructs one-hidden-layer feedforward neural network with fewer number of hidden units and weights, while simultaneously provide improved generalization and recognition performance capabilities.

Journal ArticleDOI
TL;DR: This article collected data of various sorts (demographics, language-learning history, contact with native speakers, use of the language in the field, etc.) as they relate to participants in SLA research studies to understand more about language acquisition and use.
Abstract: Efforts to gather data of various sorts—demographics, language-learning history, contact with native speakers, use of the language in the field—as they relate to participants in SLA research studies are inherent to understanding more about language acquisition and use. Scholars frequently develop questionnaires of their own, which are rarely shared widely in the profession. Consequently, much time and effort is invested in reinventing the process of gathering the types of data that are commonly needed. This research was funded in part by a grant to Barbara F. Freed from the Council for International Educational Exchange (New York), in part by a grant from the Natural Sciences and Engineering Research Council of Canada to Norman Segalowitz, and in part by a grant from the Dean's Office, Faculty of Arts and Science, at Concordia University to Segalowitz.

Proceedings ArticleDOI
20 Jun 2004
TL;DR: In this article, a new implementation of a perturbation and observation (P&O) maximum power point tracking (MPPT) algorithm that can mitigate/reduce the main drawbacks commonly related to the P&O method is discussed.
Abstract: This paper discusses a new implementation of a perturbation and observation (P&O) maximum power point tracking (MPPT) algorithm that can mitigate/reduce the main drawbacks commonly related to the P&O method. This is achieved with peak current control, small perturbation values and sampling of instantaneous values, instead of averaged, to speed up the system response and reduce the oscillations around the maximum power point (MPP). The number of samples per switching cycle, type (synchronized/ unsynchronized) and ideal instant for sampling (maximum or minimum current) are investigated in order to obtain fast calculation of the direction of the next perturbation. Experimental results with the proposed control scheme implemented in a DSP are presented.

Journal ArticleDOI
TL;DR: The authors applied expectancy theory to integrate the numerous and disparate explanations that researchers and educators have proposed to account for teacher resistance to implementing cooperative learning as an educational innovation, and found that increased emphasis on professional development should be used to enhance teachers' beliefs that they can succeed in implementing an innovation in their own context.
Abstract: This study applied expectancy theory to integrate the numerous and disparate explanations that researchers and educators have proposed to account for teacher resistance to implementing cooperative learning as an educational innovation. The cooperative learning implementation questionnaire (CLIQ) contained 48 items grouped under three broad motivational categories: perceived value of the innovation, expectancy of success, and perceived cost. These items accounted for 42.3% of the total variance in self-reported use of cooperative learning among 933 teachers. Expectancy of success issues were most important in differentiating users and non-users, suggesting that increased emphasis on professional development should be used to enhance teachers' beliefs that they can succeed in implementing an innovation in their own context. This may require both follow-up support and adaptation of the innovation.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the relationship between the comfort level of typical human activities and major weather parameters through questionnaire surveys, field measurements and statistical analyses, revealing the integrated effects of wind speed, air temperature, relative humidity and solar radiation on the human perception, preference and overall comfort in an urban environment.