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Main Ideas (main + idea)
Selected AbstractsCombining interface damage and friction in a cohesive-zone modelINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2006Giulio Alfano Abstract A new method to combine interface damage and friction in a cohesive-zone model is proposed. Starting from the mesomechanical assumption, typically made in a damage-mechanics approach, whereby a representative elementary area of the interface can be additively decomposed into an undamaged and a fully damaged part, the main idea consists of assuming that friction occurs only on the fully damaged part. The gradual increase of the friction effect is then a natural outcome of the gradual increase of the interface damage from the initial undamaged state to the complete decohesion. Suitable kinematic and static hypotheses are made in order to develop the interface model whereas no special assumptions are required on the damage evolution equations and on the friction law. Here, the Crisfield's interface model is used for the damage evolution and a simple Coulomb friction relationship is adopted. Numerical and analytical results for two types of constitutive problem show the effectiveness of the model to capture all the main features of the combined effect of interface damage and friction. A finite-step interface law has then been derived and implemented in a finite-element code via interface elements. The results of the simulations made for a fibre push-out test and a masonry wall loaded in compression and shear are then presented and compared with available experimental results. They show the effectiveness of the proposed model to predict the failure mechanisms and the overall structural response for the analysed problems. Copyright © 2006 John Wiley & Sons, Ltd. [source] ORGANIZATIONAL PORTFOLIO THEORY: PERFORMANCE-DRIVEN ORGANIZATIONAL CHANGECONTEMPORARY ECONOMIC POLICY, Issue 4 2000L DONALDSON The article outlines some of the main ideas of a new organizational theory: organizational portfolio theory. The literature has empirically established that organizations tend not to make needed adaptive changes until they suffer a crisis of low organizational performance. Organizational portfolio theory takes this idea and constructs a theory of the conditions under which organizational performance becomes low enough for adaptive organizational change to occur. The focus is on the interaction between organizational misfit and the other causes of organizational performance. To model these interactions use is made of the concepts of risk and portfolio. [source] Decision making beyond arrow's "impossibility theorem," with the analysis of effects of collusion and mutual attractionINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 1 2009Hung T. Nguyen In 1951, K.J. Arrow proved that, under certain assumptions, it is impossible to have group decision-making rules that satisfy reasonable conditions like symmetry. This Impossibility Theorem is often cited as a proof that reasonable group decision-making is impossible. We start our article by remarking that Arrow's result covers only those situations when the only information we have about individual preferences is their binary preferences between the alternatives. If we follow the main ideas of modern decision making and game theory and also collect information about the preferences between lotteries (i.e., collect the utility values of different alternatives), then reasonable decision-making rules are possible, e.g., Nash's rule in which we select an alternative for which the product of utilities is the largest possible. We also deal with two related issues: how we can detect individual preferences if all we have is preferences of a subgroup and how we take into account the mutual attraction between participants. © 2008 Wiley Periodicals, Inc. [source] Cross-cultural study on adult age-group differences in the recall of the literal and interpretive meanings of narrative text1JAPANESE PSYCHOLOGICAL RESEARCH, Issue 2 2006AYA HOSOKAWA Abstract:, This study examined cultural and age differences in the recall of the literal and interpretive meanings of narrative text. Twenty Japanese younger adults (age: M = 21.05, SD = 1.02), 20 Japanese older adults (age: M = 66.95, SD = 1.71), 20 American younger adults (age M = 21.7, SD = 1.76), and 16 American older adults (age M = 69.56, SD = 3.43) participated in this study. One story rich in both literal and interpretive content was used as a stimulus text for two recall tasks, to retell and interpret the story. The response task order was counterbalanced across the participants for each group. When asked to retell a story as close to the original as possible, the younger adults in both of the two cultural groups recalled more of the literal propositions than did the older adults. Both older and younger adults in the two cultural groups recalled more of the main ideas relative to the details; however, when asked to interpret the same story, more older than younger adults represented deep and synthetic representations of the story's interpretive meanings in the Japanese group. The interpretive responses by both the older and younger adults were almost to the same extent on depth; however, the younger adults' responses were slightly higher on synthesis in the American group. These interpretive patterns stem from cultural background. [source] Text genre as a factor in the formation of scientific literacyJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 4 2005Ayelet Baram-Tsabari Learning using primary literature may be a way of developing a capacity for scientific ways of thinking among students. Since reading research articles is a difficult task for novices, we examined the possible benefits of learning using primary literature versus secondary literature, particularly with respect to their influence on the creation and formation of scientific literacy. We report on a comparison between four groups of high school students, each with differing degrees of prior knowledge in biology, who read a domain-related text written in either the scientific research article genre (adapted primary literature) or the popular-scientific genre (secondary literature). Although there was no significant difference in the students' ability to summarize the main ideas of each text, indicating that there was no eminent distinction in their content, we found that students who read adapted primary literature demonstrated better inquiry skills, whereas secondary literature readers comprehended the text better and demonstrated less negative attitudes toward the reading task. Since the scientific content of the two texts was essentially identical, we suggest that the differences in students' performances stem from the structure of the text, dictated by its genre. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 403,428, 2005 [source] The Effect of Frequency of Input-Enhancements on Word Learning and Text ComprehensionLANGUAGE LEARNING, Issue 2 2007Susanne Rott Research on second language lexical development during reading has found positive effects for word frequency, the provision of glosses, and elaborative word processing. However, findings have been inconclusive regarding the effect of such intervention tasks on long-term retention. Likewise, few studies have looked at the cumulative effect of interventions on word learning or text comprehension. This investigation sought to assess the effect of increased frequency of target words (TWs) comparing lexical gain of words that occurred once (F1) or four times (F4) in the input passage. The study further investigated the combined effect of frequency (F4) and semantic or visual enhancements. It compared the following reading conditions: (a) TWs were glossed four times in the text (four-gloss: 4G); (b) TWs were first glossed, then retrieved in the first language, and bolded twice (gloss-retrieval: GR); and (c) TWs were first glossed and then bolded three times (gloss-bolding: GB). In addition, the study assessed the effect of these interventions on long-term retention (4,6 weeks) of lexical knowledge and on text comprehension. Findings revealed that the GR and 4G reading conditions resulted in more productive word gain than the GB condition or when readers encountered a TW only once. Repeated visual enhancements seemed to have no effect on strengthening word encoding. The comprehension of main ideas was highest when the TW was glossed four times followed by the gloss-bolding reading condition and the gloss-retrieval task. [source] Justification as a Process of DiscoveryRATIO JURIS, Issue 4 2000Rauno Halttunen Legal decision-making interests theoreticians in our discipline largely in terms of how a legal decision is justified. In his book, Bruce Anderson (1996) has posited a distinction between how a decision is arrived at, on one hand, and how it is justified, on the other. Anderson seems to be suggesting that legal theory should set out to continue the work of the American realists, that is, to develop legal decision-making as a process of discovery towards a solution. In my presentation, I will be looking at legal decision-making as a process of finding or discovering knowledge. What I mean by "discovery," however, is the discovery of new scientific knowledge. (The theory of science draws a distinction between proving and discovering knowledge.) I submit that for a justification to be valid the arguments comprising it ought to fulfill the logical conditions stipulated for the discovery of knowledge. In the present paper, I also hope to share with you the main ideas of a book I am currently writing on the subject. [source] A tutorial on , -support vector machinesAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 2 2005Pai-Hsuen Chen Abstract We briefly describe the main ideas of statistical learning theory, support vector machines (SVMs), and kernel feature spaces. We place particular emphasis on a description of the so-called , -SVM, including details of the algorithm and its implementation, theoretical results, and practical applications. Copyright © 2005 John Wiley & Sons, Ltd. [source] A rhythm recognition computer program to advocate interactivist perceptionCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 1 2004Jean-Christophe Buisson Abstract This paper advocates the main ideas of the interactive model of representation of Mark Bickhard and the assimilation/accommodation framework of Jean Piaget, through a rhythm recognition demonstration program. Although completely unsupervised, the program progressively learns to recognize more and more complex rhythms struck on the user's keyboard. It does so without any recording of the input flow, and without any pattern matching in the usual sense. On the contrary, internal processes are dynamically constructed to follow and anticipate the user's actions. We show that these processes are representations of the rhythms in the interactivist sense, and that they emerge from non representational grounds, avoiding the symbol-grounding problem. They are not copies or transductions of reality, but ideal internal constructions of the agent, avoiding the circularity pointed out by Piaget. In practice, the active nature of this recognition process allows it to work even with noisy and complex input flows. [source] | ||||||||||