• Title/Summary/Keyword: close-form solution

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Numerical investigation of RC structural walls subjected to cyclic loading

  • Cotsovos, D.M.;Pavlovic, M.N.
    • Computers and Concrete
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    • v.2 no.3
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    • pp.215-238
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    • 2005
  • This work is based on a nonlinear finite-element model with proven capacity for yielding realistic predictions of the response of reinforced-concrete structures under static monotonically-increasing loading. In it, the material description relies essentially on the two key properties of triaxiality and brittleness and, thus, is simpler than those of most other material models in use. In this article, the finite-element program is successfully used in investigating the behaviour of a series of RC walls under static cyclic loading. This type of loading offers a more strenuous test of the validity of the proposed program since cracks continuously form and close during each load cycle. Such a test is considered to be essential before attempting to use the program for the analysis of concrete structures under seismic excitation in order to ensure that the solution procedure adopted is numerically stable and can accurately predict the behaviour of RC structures under such earthquake-loading conditions. This is achieved through a comparative study between the numerical predictions obtained presently from the program and available experimental data.

Optimal Stocking for Age-replaced Non-repairable Items (수리 불가능한 품목의 수명교환을 위한 최적 재고정책)

  • Park, Young-Taek;Park, Kyung-Soo
    • Journal of the Korean Operations Research and Management Science Society
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    • v.14 no.2
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    • pp.75-86
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    • 1989
  • Joint stocking and preventive age replacement policy is considered for non-repairable items assuming instantaneous replenishment. A recursive relationship among the optimal preventive replacement ages is obtained, which shows that the preventive replacement ages in a replenishment cycle form an increasing sequence due to the inventory carrying cost. Using this relationship, a procedure is given for determining how many units to purchase on each order and when to replace each unit after it has begun operating so as to minimize the total cost per unit time over an infinite time span. The problem can be simplified if equal preventive replacement ages are assumed, and the solution is very close to that of the original unconstrained problem.

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K-Way Graph Partitioning: A Semidefinite Programming Approach (Semidefinite Programming을 통한 그래프의 동시 분할법)

  • Jaehwan, Kim;Seungjin, Choi;Sung-Yang, Bang
    • Proceedings of the Korean Information Science Society Conference
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    • 2004.10a
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    • pp.697-699
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    • 2004
  • Despite many successful spectral clustering algorithm (based on the spectral decomposition of Laplacian(1) or stochastic matrix(2) ) there are several unsolved problems. Most spectral clustering Problems are based on the normalized of algorithm(3) . are close to the classical graph paritioning problem which is NP-hard problem. To get good solution in polynomial time. it needs to establish its convex form by using relaxation. In this paper, we apply a novel optimization technique. semidefinite programming(SDP). to the unsupervised clustering Problem. and present a new multiple Partitioning method. Experimental results confirm that the Proposed method improves the clustering performance. especially in the Problem of being mixed with non-compact clusters compared to the previous multiple spectral clustering methods.

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Application of Step Length Technique To An Eigensolution Method for Non-proportionally Damped Systems (Step Length를 이용한 비비례감쇠시스템의 고유치 해석)

  • Thanh X. H;Kim, Byoung-Wan;Jung, Hyung-Jo;Lee, In-Won
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2003.03a
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    • pp.481-490
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    • 2003
  • This paper presents an efficient eigensolution method for non-proportionally damped systems. The proposed method is obtained by applying the accelerated Newton-Raphson technique and the orthonormal condition of the eigenvectors to the linearized form of the quadratic eigenproblem. A step length and a selective scheme are introduced to increase the convergence of the solution. The step length can be evaluated by minimizing the norm of the residual vector using the least square method. While the singularity may occur during factorizing process in other iteration methods such as the inverse iteration method and the subspace iteration method if the shift value is close to an exact eigenvalue, the proposed method guarantees the nonsingularity by introducing the orthonormal condition of the eigenvectors, which can be proved analytically. A numerical example is presented to demonstrate the effectiveness of the proposed method.

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Near Minimum-Time Trajectory Planning for Wheeled Mobile Robots with Piecewise Constant Voltages

  • Park, Jong-Suk;Kim, Munsang;Kim, Byung-Kook
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.30.6-30
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    • 2001
  • We build near minimum-time trajectory planning algorithm for Wheeled mobile robots (WMRs) With Piece-Wise Constant control voltages satisfying i) initial and final postures and velocities as well as ii) voltage constraints We consider trajectory planning problem for cornering motion with a path-deviation requirement for obstacle avoidance. We divide our trajectory planning algorithm for cornering motion into five ordered sections: translational, transient, rotational, transient, and translational sections. Transforming dynamics into uncorrelated form with respect to translational and rotational velocities, we can make controls for translation/rotational velocities to be independent. By planning each section with constant voltages, and integrating five sections with adjustment of numbers of steps, the overall trajectory is planned. The performance is very close to the minimum-time solution, which is validated via simulation studies.

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Stochastic along-wind response of nonlinear structures to quadratic wind pressure

  • Floris, Claudio;de Iseppi, Luca
    • Wind and Structures
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    • v.5 no.5
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    • pp.423-440
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    • 2002
  • The effects of the nonlinear (quadratic) term in wind pressure have been analyzed in many papers with reference to linear structural models. The present paper addresses the problem of the response of nonlinear structures to stochastic nonlinear wind pressure. Adopting a single-degree-of-freedom structural model with polynomial nonlinearity, the solution is obtained by means of the moment equation approach in the context of It$\hat{o}$'s stochastic differential calculus. To do so, wind turbulence is idealized as the output of a linear filter excited by a Gaussian white noise. Response statistical moments are computed for both the equivalent linear system and the actual nonlinear one. In the second case, since the moment equations form an infinite hierarchy, a suitable iterative procedure is used to close it. The numerical analyses regard a Duffing oscillator, and the results compare well with Monte Carlo simulation.

Random Noise Effect Upon 2nd Order Analog Phase-Locked Loop (Random Noise가 2차 Analog Phase-Locked Loop에 미치는 영향)

  • Kang, Jeoung Soo;Rhee, Man Young
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.23 no.5
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    • pp.605-615
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    • 1986
  • The phase-locked loop(PLL) is a communication receiver which operates as a coherent detector by continuously correcting the phase error. In this paper analysis for the Phase-error behavior of analog phase-locked loop (APLL) in the presence of additive white gaussian noise has been done theoretically and experimentally. A close form solution of the first-order loop is obtained and approximate solutions are derived for the second-order loops with RC, leadlag and perfect integrator filters. The perdormance of APLL's and their characteristics are also thoroughly investigated through experiments. In order to analyze the effect of the stochastic nature on nonlinear dynamics characteristics of the second order APLL, the phase error distribution and its variance have been obtained by using the Fokker-Planck equation. Theoretical results agree closely with those of experiment.

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Crack effect on the elastic buckling behavior of axially and eccentrically loaded columns

  • Zhou, L.;Huang, Y.
    • Structural Engineering and Mechanics
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    • v.22 no.2
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    • pp.169-184
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    • 2006
  • A close form solution of the maximum deflection for cracked columns with rectangular cross-sections was developed and thus the elastic buckling behavior and ultimate bearing capacity were studied analytically. First, taking into account the effect of the crack in the potential energy of elastic systems, a trigonometric series solution for the elastic deflection equation of an arbitrary crack position was derived by use of the Rayleigh-Ritz energy method and an analytical expression of the maximum deflection was obtained. By comparison with the rotational spring model (Okamura et al. 1969) and the equivalent stiffness method (Sinha et al. 2002), the advantages of the present solution are that there are few assumed conditions and the effect of axial compression on crack closure was considered. Second, based on the above solutions, the equilibrium paths of the elastic buckling were analytically described for cracked columns subjected to both axial and eccentric compressive load. Finally, as examples, the influence of crack depth, load eccentricity and column slenderness on the elastic buckling behavior was investigated in the case of a rectangular column with a single-edge crack. The relationship of the load capacity of the column with respect to crack depth and eccentricity or slenderness was also illustrated. The analytical and numerical results from the examples show that there are three kinds of collapse mechanisms for the various states of cracking, eccentricity and slenderness. These are the bifurcation for axial compression, the limit point instability for the condition of the deeper crack and lighter eccentricity and the fracture for higher eccentricity. As a result, the conception of critical transition eccentricity $(e/h)_c$, from limit-point buckling to fracture failure, was proposed and the critical values of $(e/h)_c$ were numerically determined for various eccentricities, crack depths and slenderness.

Essay on Form and Function Design (디자인의 형태와 기능에 관한 연구)

  • 이재국
    • Archives of design research
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    • v.2 no.1
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    • pp.63-97
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    • 1989
  • There is nothing more important than the form and function in design, because every design product can be done on the basis of them. Form and Function are already existed before the word of design has been appeared and all the natural and man-made things' basic organization is based on their organic relations. The organic relations is the source of vitality which identifies the subsistance of all the objects and the evolution of living creatures has been changed their appearances by the natural law and order. Design is no exception. Design is a man-made organic thing which is developed its own way according to the purposed aim and given situations. If so, what is the ultimate goal of design. It is without saying that the goal is to make every effort to contribute to the -human beings most desirable life by the designer who is devoting himself to their convenience and well-being. Therefore, the designer can be called the man of rich life practitioner. This word implies a lot of meanings since the essence of design is improving the guality of life by the man-made things which are created by the designer. Also, the things are existed through the relations between form and function, and the things can keep their value when they are answered to the right purpose. In design, thus, it is to be a main concern how to create valuable things and to use them in the right way, and the subject of study is focused on the designer's outlook of value and uk relations between form and function. Christopher Alexander mentioned the importance of form as follows. The ultimate object of design is form. Every design problem begins with an effort to achieve fittness between the form and its context. The form is the solution to the problem: the context defmes the problem. In other words, when we speak of design, the real object of discussion is not form alone, but the ensemble comprising the form and its context. Good fit is a desirable property of this ensemble which relates to some particular division of the ensemble into form and context. Max Bill mainatined how important form is in design. Form represents a self-contained concept, and its embodiment in an object results in that object becoming a work of art. Futhermore, this explains why we use form so freguently in a comparative sense for determining whether one thing is less or more beautiful than another, and why the ideal of absolute beauty is always the standard by which we appraise form, and through form, art itself. Hence form has became synonymous with beauty. On the other hand, Laszlo Moholy-Nagy stated the importance of function as follows. Function means the task an object is designed to fulfill the task instrument is shaping the form. Unfortunately, this principle was not appreciated at the same time but through the endeavors of Frank Lloyd Wright and of the Bauhaus group and its many collegues in Europe, the idea of functionalism became the keynote of the twenites. Functionalism soon became a cheap slogan, however, and its original meaning blurred. It is neccessary to reexamine it in the light of present circumstances. Charles William Eliot expressed his idea on the relations between function and beauty. Beauty often results chiefly from fittness: indeed it is easy to manitain that nothing is fair except what is fit its uses or functions. If the function of the product of a machine be useful and valuable, an the machine be eminently fit for its function, it conspicuously has the beauty of fittness. A locomotive or a steamship has the same sort of beauty, derived from the supreme fittness for its function. As functions vary, so will those beauty..vary. However, it is impossible to study form and function in separate beings. Function can't be existed without form, and without function, form is nothing. In other words, form is a function's container, and function is content in form. It can be said that, therefore, the form and function are indispensable and commensal individuals which have coetemal relations. From the different point of view, sometimes, one is more emphasized than the other, but in this case, the logic is only accepted on the assumption of recognizing the importance of the other's entity. The fact can be proved what Frank Hoyd wright said that form and function are one. In spite of that, the form and function should be considered as independent indivisuals, because they are too important to be treated just as the simple single one. Form and function have flexible properties to the context. In other words, the context plays a role as the barometer to define the form and function, also which implies every meaning of surroun'||'&'||'not;dings. Thus, design is formed under the influence of situations. Situations are dynamic, like the design process itself, in which fixed focus can be cripping. Moreover, situations control over making the good design. Judging from the respect, I defined the good design in my thesis An Analytic Research on Desigh Ethic, "good design is to solve the problem by the most proper way in the situations." Situations are changeable, and so is design. There is no progress without change, but change is not neccessarily progress. It is highly desirable that there changes be beneficial to mankind. Our main problem is to be able to discriminate between that which should be discarded and that which should be kept, built upon, and improved. Form and Function are no exception. The practical function gives birth to the inevitable form and the $$\mu$ti-classified function is delivered to the varieties of form. All of these are depended upon changeable situations. That is precisely the situations of "situation de'||'&'||'not;sign", the concept of moving from the design of things to the design of the circumstances in which things are used. From this point of view, the core of form and function is depended upon how the designer can manage it efficiently in given situations. That is to say that the creativity designer plays an important role to fulfill the purpose. Generally speaking, creativity is the organization of a concept in response to a human need-a solution that is both satisfying and innovative. In order to meet human needs, creative design activities require a special intuitive insight which is set into motion by purposeful imagination. Therefore, creativity is the most essential quality of every designer. In addition, designers share with other creative people a compulsive ingenuity and a passion for imaginative solutions which will meet their criteria for excellence. Ultimately, it is said that the form and function is the matter which belongs to the desire of creative designers who constantly try to bring new thing into being to create new things. In accordance with that the main puppose of this thesis is to catch every meaning of the form and function and to close analyze their relations for the promotion of understanding and devising practical application to gradual progression in design. The thesis is composed of four parts: Introduction, Form, Function and Conclusion. Introduction, the purpose and background of the research are presented. In Chapter I, orgin of form, perception of form, and classification of form are studied. In Chapter II, generation of function, development of function, and diversification of function are considered. Conclusion, some concluding words are mentioned.ioned.

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The Origin and Mineralogy of the Dongyang Talc Deposit (동양활석광상(東洋滑石鑛床)에서 산출(産出)되는 활석(滑石)에 대한 광물화학적(鑛物化學的) 및 성인적(成因的) 연구(硏究))

  • Moon, Hi-soo;Kim, Seong Tae
    • Economic and Environmental Geology
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    • v.21 no.3
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    • pp.235-255
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    • 1988
  • Talc deposit of pipe-like form occurrs in the lower part of the Hyangsanri Dolomite with a strike of N40 -50 E and a dip of 40 -50 NW which is one formation of the Ogcheon Super Croup. The pipi-like ore body plunge at about $40^{\circ}$ to the west and are parallel to the lineation developed in the area. Structural formulae of tales occurred in this deposit are close to the ieal composition $Mg_6Si_8O_{20}(OH)_4$ showing limited deviation from ideal one. Substitution of Al for Si in tetrahedral site is of little or nothing ranging 0-0.04 and octahedral occupancy is close to six ranging 5.88-5.98 atoms per unit cell. Predominant octahedaral cation is Mg and proportion of divalent cations is generally over 97percent. Calcite -dolomite thermometry is obtained by determining the mol % $MgCO_3$using of EPMA and XRD methods. The peak metamorphic temperature can be estimated at $470{\pm}30^{\circ}C$ in the area whereas carbonates occurred at near talc ore show lower temperature than $400^{\circ}C$ that the calcite solvus limit is not well established. It indicates that the talc deposit was formed at the lower temperature that the metamorphic temperature. Cosequently, the formation of talc by metamorphism is questionable and the alteratin zone developed around the talc ore is very limited. The occurrence of talc ore in the dolomite as well as mineralogy, calcite-dolomite geothermometry, chlorite geothermometry, field and microscopic evidence suggest that siliceous ascending hydrothermal solution along the fracture is responsible for the formation of talc. It was considered that the slight fracturing of dolomite was formed by deformation prior to the mineralization.

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