1,721,008 research outputs found
Highly accurate computation of spatial-dependent heat conductivity and heat capacity in inverse thermal problem
No full textThe optimization framework of identification for elastoplasticity
No full text本論文旨在研究彈塑性模式的識別問題,並且提出一致的方法來估測模式參數與初始狀態。本文特別注意實際收到的材料、既存的結構物，其內變數事實上不能假設初值為零。首先,提出一個廣泛的彈塑性模式。根據此模式,建立其彈塑性識別的動態最佳化架構。對於這個包含等式約束、不等式約束與互補約束的最佳化問題，本文獲得其正確的最佳化條件。文中所得結果之特色在於呈現凸與辛之特性。於現代實驗資料擷取朝向離散數位化之趨勢，本文除了處理識別之連續時間最佳化問題外,也考慮識別之離散時間最佳化問題,所得離散解條件也保有辛群之特性。依據實務的狀況，本文提出一個估測模式參數與初始狀態的演算法並且實際以實驗資料來識別模式之參數與初始狀態。The identification problem of elastoplastic models are addressed and a unified way to estimate the optimal values of model parameters and initial states is proposed. Special attention is drawn to materials as received and structures as existing for which initial values of internal state variables could no longer be assumed to vanish. A comprehensive model of elastoplasticity is formulated first and then a dynamic optimization framework for the identification problem of the elastoplastic model is established. A correct optimality condition of the dynamic optimization problem subjected to constraints in the forms of equalities, inequalities, and complementarity constraints is obtained. The important feature of our results is that they are convex and symplectic. In view of modern trends of digital data acquisition in experiments,e further consider the discrete-time version in addition to the continuous-time optimization problem, and obtain discrete conditions of solution which are proved to preserve the structure of a symplectic group.he algorithm of finding the optimal values of parameters and initial states is proposed. Experimental data were used to identify them in several testing and real cases.Contents試委員審定書 I謝 III要 IVotation convention VI Introduction 1 Dynamic optimization 4.1 Dynamic programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Variational method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 Relation between dynamic programming and variational method . . . . . . . 6.4 Treatment of equality and inequality constraints . . . . . . . . . . . . . . . . 8.5 Treatment of complementarity constraints and the mathematical programsith complementarity constraints . . . . . . . . . . . . . . . . . . . . . . . . . 10 Dynamic optimization study of elastoplastic model identification 13.1 A comprehensive model of elastoplasticity . . . . . . . . . . . . . . . . . . . . 13.2 The elastoplastic models included in the comprehensive model of elastoplasticity 14.3 Optimization framework of parameter identification problems . . . . . . . . . 16.4 Necessary and sufficient conditions in identification of elastoplastic model . . 18.5 Two point boundary value problem in identification of elastoplastic model . . 22.6 The role of costate variables in identification problem . . . . . . . . . . . . . 23 Group preserving scheme in identification of elastoplastic model 26.1 The symmetry property in dynamic optimization . . . . . . . . . . . . . . . . 26.2 Discrete symplectic formulation for identification of elastoplastic model . . . 27.3 Lie group preserving scheme in ordinary differential equations . . . . . . . . . 30 Numerical method for solving two point boundary value problem in identificationf elastoplastic model 33.1 Fictitious time integration method and its modified approach . . . . . . . . . 33.2 Numerical method for solving two point boundary value problem . . . . . . . 34.3 Numerical examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.3.1 Perfect elastoplasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.3.2 Prandtl-Reuss model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.3.3 Bilinear elastoplasticity . . . . . . . . . . . . . . . . . . . . . . . . . . 43.3.4 Material model consisting of bilinear elastoplasticity and linear elasticity 45.3.5 Material model consisting of Armstrong-Frederick elastoplasticity andinear elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.3.6 Material model consisting of M perfectly elastoplastic elements in parallelnd linear elastic element . . . . . . . . . . . . . . . . . . . . . . 47 Conclusion 49eferences 51 Dynamic programming 60 Derivation from Eq.(20) to Eq.(21) 65ist of Figures Stress-strain curves of pseudo-experimental data and simulation with perfectlylastoplastic model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Experiment of axial-torsional test on SS316 . . . . . . . . . . . . . . . . . . . 67 Stress-strain curves of axial-torsional test on SS316 and simulation with Prandtl-euss model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Stress-strain curves of pseudo-experimental data and simulation with bilinearlylastoplastic model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Stress-strain curves of axial-torsional test on SS316 and simulation with materialodel BL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Stress-strain curves of axial-torsional test on SS316 and simulation with materialodel AF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71X Comparison between Prandtl-Reuss model, material model BL, material modelF in stress history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Stress-strain curves of axial-torsional test on SS316 and simulation with materialodel PEIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
EMG classification for prehensile postures using cascaded architecture of neural networks with self-organizing maps
No full textDispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
On Yield Surface Detection, Experiments by Finite Element Method
No full textIn the submitted report it is described, how experiments by FEM are designed for\nmore precise detection of yield point. Content of report can be devided to these\nareas:\n- Intership travel report\n- Idea of research topic\n- Develop software tool
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