1,721,178 research outputs found
Optomechatronic technology: The characteristics and perspectives
No full textIn recent years, optical technology has been incorporated into mechatronic systems at an accelerated rate, and as a result, a great number of machines/systems with smart optical components have been introduced. This integrated technology is termed "optomechatronics." This paper introduces the fundamental concept, definition, and characteristics of the technology by analyzing the characteristics of a variety of practical optomechatronic systems. The introduction describes how optical and mechatronic components are physically coupled to each other to form optomechatronic integration. With this observation, we describe the nature and integration concept of the technology, from which we can derive the technology-driven fundamental functionalities in some detail. Based upon the knowledge on basic optomechatronic integration and functions, we analyze optomechatronic systems in general from the viewpoint of system configuration and design and, thus, the roles of optical technology in overall system performance being learned and the synergistic effects due to its fusion with mechatronics being understood
Analysis of radiative transfer in cylindrical enclosures using the finite volume method
No full textRadiative heat transfer in a cylindrical enclosure with or without a concentric cylinder containing absorbing-, emitting-, and isotropically- or anisotropically-scattering media is studied by using the finite volume method (FVM) for radiation. Since the unit direction vector is defined with respect to the Cartesian base vectors, the intrinsic difficulty in treating an angular derivative encountered in the discrete ordinates method (DOM) does not arise in the FVM. For the special case of an axisymmetric cylinder, a mapping, which transforms the dependence of intensity on two-spatial and two-angular to three-spatial and one-angular variables, was adopted. The scattering phase function is approximated by a finite series of Legendre polynomials, Several solutions are obtained in axisymmetric as well as three-dimensional cylindrical geometries with participating media and compared with others obtained by different methods, which are unique in this work. The computational efficiency of the FVM is discussed by comparison with the DOM. The problem of control angle overlaps is also examined in the last example by changing the angular grid systems
Modification of the discrete-ordinates method in an axisymmetric cylindrical geometry
No full textThe conventional discrete-ordinates method is modified and developed for the analysis of two-dimensional axisymmetric cylindrical enclosure with absorbing, emitting, and either isotropically or anisotropically scattering gray medium. The main characteristic of the present method is that the control angles can be arbitrarily specified pertaining to each problem dealt with. The scattering phase function is approximated by a finite series of Legendre polynomials. In order to validate the formulations, four benchmark problems are considered and their results are compared with other predictions or experimental data. It is shown that the present method is quite accurate, computationally efficient, and easy to use for the analysis of axisymmetric radiation heat transfer
Modeling of radiative heat transfer in an axisymmetric cylindrical enclosure with participating medium
No full textRadiative heat transfer in an axisymmetric enclosure with absorbing, emitting, and scattering medium is studied here by using the different methods such as MDOM, FVM, and MFVM with emphasis on the treatment of angular derivative term, which appears in curvilinear coordinates due to angular redistribution. After final discretization equation for MFVM is introduced by using the step scheme and directional weights, the present approach is validated by applying it to three different benchmarking problems with absorbing, emitting, and scattering medium. All of the results presented here support its accuracy as well as moderate efficiency. Finally, the present approaches are applied to a truncated cone-shaped enclosure as a body-fitted geometry case. (C) 2004 Elsevier Ltd. All rights reserved.This paper was supported by research funds of Chonbuk National University
Analysis of radiative heating of a rocket plume base with the finite-volume method
No full textThe finite-volume method for radiation is applied to investigate a radiative heating of rocket base plane due to searchlight and plume emissions. The exhaust plume is assumed to absorb, emit and scatter the radiant energy isotropically, as well as anisotropically, while the medium between the plume boundary and the base plane is cold and nonparticipating. The scattering phase function is modeled by a finite series of Legendre polynomials. After validating the benchmark solution by comparison with that of previous works obtained by the Monte-Carlo method, further investigations have been done by changing various parameters, such as plume cone angle, scattering albedo, scattering phase function, optical radius and nozzle exit temperature. The results show that the base plane is predominantly heated by the plume emission, rather than the searchlight emission, when the nozzle exit temperature is the same as that of plume. Copyright (C) 1996 Elsevier Science Ltd.The financial assistance by the Objective Research Fund of the Korea Science and Engineering Foundation is gratefully acknowledged
Numerical analysis of conduction, convection, and radiation in a gradually expanding channel
No full textThe problem with simultaneous conductive, convective, and radiative heat transfer is analyzed in a two-dimensional gradual expansion channel flow. The main objective is to generate a program to attack the radiation in a curvilinear coordinate system with momentum and energy equations involved. The governing equations are transformed into generalized coordinates. Whereas the SIMPLE algorithm developed in a body-fitted coordinate system is used to obtain the flow field solution, the finite volume method is applied to solve the radiative transfer equation. The accuracy and performance of the finite volume method for the radiation are validated in a well-known combined heat transfer problem by using a curvilinear grid system. Then detailed thermal characteristics are investigated in a gradually expanding channel through various parameters such as Prandtl number, conduction to radiation parameter, wall emissivity, and scattering albedo. Results show that radiation plays a significant role in the gradually expanding channel flow
Radiative heat transfer in a body-fitted axisymmetric cylindrical enclosure
No full textThe authors are grateful for the financial support by the Korea Science and Engineering Foundation under Contract KOSEF 971-1006-036-2
KNOWLEDGE-ASSISTED OPTIMIZATION MODEL FORMULATION - UNIK-OPT
No full textIn this paper, we describe a knowledge-assisted optimization model formulation system UNIK-OPT (UNIfied Knowledge-OPTimization). To envision the desirable features of UNIK-OPT, we first establish the design criteria of knowledge-assisted modeling systems. The most distinctive criterion pursued in this research is the independent management of knowledge base from multiple optimization models. To achieve these criteria, we articulate four levels of modeling views: semantic view, modeling language view, mathematical notational view and tabular view. In semantic view, the associations between attributes, blocks of terms and constraints are represented in a constraint network, and a block of terms is represented as a pair of coefficient and variable. Thus, the formulation reasoning is esteemed as a process of helping the construction of a specific semantic model by adding user's problem definition to the extracted relevant semantic level modeling knowledge. Then the specific semantic model can be transformed into other views of model automatically. The prototype UNIK-OPT is developed to realize this idea, and is illustrated with a refinery plant
CASE-BASED LEARNING FOR KNOWLEDGE-BASED OPTIMIZATION MODELING SYSTEM - UNIK-CASE
No full textThis article explores how the previously built optimization models can be used as a medium for automatic learning. To explain the learning process, we describe the target representation of common modeling knowledge base in UNIK-OPT and the representations of specific optimization model cases. Both are represented in frames. The common modeling knowledge is represented by the potential linkability between attributes and indices, attributes and blocks of terms, and blocks of terms and constraints. There are also no fixed indices on blocks of terms and constraint sets. Therefore, the learning process includes the addition of new frames, generalization of linkability, generalization of attribute's role (constant or variable), and context identification in terms of period, time units, usage, perspectives, and so forth. To realize the learning process, the UNIK-CASE is under development as a front end the modeling system UNIK-OPT
- …
