• Title/Summary/Keyword: Explicit Function

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Numerical Study of Natural Convection in a Rectangular Enclosure with Cooling Strip (냉각부(冷却部)를 갖는 사각형(四角形) 밀폐공간내(密閉空間內)의 자연대류(自然對流)에 관(關)한 수치해석(數値解析))

  • Lee, Cheong-Ouk;Seo, Jeong-Yun;Kim, Chong-Bo
    • Solar Energy
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    • v.6 no.2
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    • pp.54-61
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    • 1986
  • The influence on natural convection was studied by solving the partial differential equations within a rectangular enclosure which have a cooling strip at the right side wall of the space, a isothermally heated bottom plate and adiabatic two other walls. Computation was carried out for the range of Grashof number from $5*10^3$ to $2.5*10^5$ with Plandtl number of 0.73. The results have been obtained in cases of four aspect ratios and various strip sizes. Temperature and Stream function distributions have been plotted using explicit finite difference method in two dimensional, laminar flow, and also mean Nusselt number and Local Nusselt number have been obtained.

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The Numerical Analysis of Jeju Harbor Flow Considering Effect of Seasonal Wind

  • Kim, Nam-Hyeong;Park, Ji-Hun;Kang, Hyun-Woo
    • Journal of Navigation and Port Research
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    • v.31 no.9
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    • pp.793-799
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    • 2007
  • The effect of seasonal wind on the tidal circulation in Jeju harbor was examined by using a numerical shallow water model. A finite element for analyzing shallow water flow is presented. The Galerkin method is employed for spatial discretization. Two step explicit finite element scheme is used to discretize the time function, which has advantage in problems treating large numbers of elements and unsteady state. The numerical simulation is compared with three cases; Case 1 does not consider the effect of wind, Case 2 and Case 3 consider the effect of summer and winter seasonal wind, respectively. According to result considering effect of seasonal wind, velocity of current vector shows slightly stronger than that of case 1 in the flow field. It can be concluded that the present method is a useful and effective tool in tidal current analysis.

Latent Keyphrase Extraction Using Deep Belief Networks

  • Jo, Taemin;Lee, Jee-Hyong
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.15 no.3
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    • pp.153-158
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    • 2015
  • Nowadays, automatic keyphrase extraction is considered to be an important task. Most of the previous studies focused only on selecting keyphrases within the body of input documents. These studies overlooked latent keyphrases that did not appear in documents. In addition, a small number of studies on latent keyphrase extraction methods had some structural limitations. Although latent keyphrases do not appear in documents, they can still undertake an important role in text mining because they link meaningful concepts or contents of documents and can be utilized in short articles such as social network service, which rarely have explicit keyphrases. In this paper, we propose a new approach that selects qualified latent keyphrases from input documents and overcomes some structural limitations by using deep belief networks in a supervised manner. The main idea of this approach is to capture the intrinsic representations of documents and extract eligible latent keyphrases by using them. Our experimental results showed that latent keyphrases were successfully extracted using our proposed method.

THE LOGARITHMIC KUMARASWAMY FAMILY OF DISTRIBUTIONS: PROPERTIES AND APPLICATIONS

  • Ahmad, Zubair
    • Communications of the Korean Mathematical Society
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    • v.34 no.4
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    • pp.1335-1352
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    • 2019
  • In this article, a new family of lifetime distributions by adding two additional parameters is introduced. The new family is called, the logarithmic Kumaraswamy family of distributions. For the proposed family, explicit expressions for some mathematical properties are derived. Maximum likelihood estimates of the model parameters are also obtained. This method is applied to develop a new lifetime model, called the logarithmic Kumaraswamy Weibull distribution. The proposed model is very flexible and capable of modeling data with increasing, decreasing, unimodal or modified unimodal shaped hazard rates. To access the behavior of the model parameters, a simulation study has been carried out. Finally, the potentiality of the new method is proved via analyzing two real data sets.

Nonlinear vibration analysis of a type of tapered cantilever beams by using an analytical approximate method

  • Sun, Weipeng;Sun, Youhong;Yu, Yongping;Zheng, Shaopeng
    • Structural Engineering and Mechanics
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    • v.59 no.1
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    • pp.1-14
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    • 2016
  • In this paper, an alternative analytical method is presented to evaluate the nonlinear vibration behavior of single and double tapered cantilever beams. The admissible lateral displacement function satisfying the geometric boundary conditions of a single or double tapered cantilever beam is derived by using Rayleigh-Ritz method. Based on the Lagrange method and the Newton Harmonic Balance (NHB) method, analytical approximate solutions in closed and explicit form are obtained. These approximate solutions show excellent agreement with those of numeric method for small as well as large amplitude. Moreover, due to brevity of expressions, the present analytical approximate solutions are convenient to investigate effects of various parameters on the large amplitude vibration response of tapered beams.

Robust Newsvendor Model with Customer Balking by the Bi-levels of Inventory Threshold (이중 재고한계점에 반응하는 고객이탈행위를 고려한 강건한 뉴스벤더 모델)

  • Jung, Uk;Lee, Se Won
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.36 no.1
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    • pp.36-43
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    • 2013
  • Many retailer store managers are experiencing the situation where some customers balk at purchasing products if the stock is low. In this paper, we extend the single period newsvendor model in an environment of customer balking behavior occurring at double threshold inventory levels assuming the chance of sales during balking is a discrete function of inventory level. Our analysis is based on the assumption that only the mean and the variance of demand are known, without assuming any specific distributional form. We derive the explicit general expression of optimal order quantity with unknown distribution of demand with double threshold inventory levels of customer balking. Then, we illustrate the concepts developed here through simple numerical examples and conclude the future research topics under balking situation.

AN EFFICIENT HYBRID NUMERICAL METHOD FOR THE TWO-ASSET BLACK-SCHOLES PDE

  • DELPASAND, R.;HOSSEINI, M.M.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.25 no.3
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    • pp.93-106
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    • 2021
  • In this paper, an efficient hybrid numerical method for solving two-asset option pricing problem is presented based on the Crank-Nicolson and the radial basis function methods. For this purpose, the two-asset Black-Scholes partial differential equation is considered. Also, the convergence of the proposed method are proved and implementation of the proposed hybrid method is specifically studied on Exchange and Call on maximum Rainbow options. In addition, this method is compared to the explicit finite difference method as the benchmark and the results show that the proposed method can achieve a noticeably higher accuracy than the benchmark method at a similar computational time. Furthermore, the stability of the proposed hybrid method is numerically proved by considering the effect of the time step size to the computational accuracy in solving these problems.

Numerical investigations on the effect of tortuosity on friction factor in superconducting CICC configuration

  • Vaghela, Hitensinh;Lakhera, Vikas;Bhatt, Kunal;Sarkar, Biswanath
    • Progress in Superconductivity and Cryogenics
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    • v.23 no.4
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    • pp.49-55
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    • 2021
  • The Cable in Conduit Conductor (CICC) configurations are designed, tested and realized to make high field superconducting (SC) magnets. The evolution of CICC design makes it challenging to forecast thermo-hydraulic behavior. A common objective of thermo-hydraulic studies is to obtain the most reliable predictive correlation for friction factor in CICC geometries and to reduce the dependency on the experiment. So far, only the void fraction and Reynolds number have been considered in the predictive correlations in an explicit way. In the present paper, the CICC twisting pattern dependency, called tortuosity (τ), on the pressure drop prediction, has been assessed through a numerical simulation approach. The CICC twisting pattern with 6+1 petals (solid conductor in the present study) with different twisting pitches is mimicked in the numerical simulation for the range 100 ≤ Re ≤10000 and 1 < τ < 1.08 and a correlation for friction factor, f, has been proposed as a function of Re and τ.

Classical Relativistic Extension of Kanai's Frictional Lagrangian

  • Dubey, Ritesh Kumar;Singh, B.K.
    • Journal of the Korean Physical Society
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    • v.73 no.12
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    • pp.1840-1844
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    • 2018
  • Working in an arbitrary Lorentz frame, we address the question of formulating the covariant variational principle for classical, single-particle, dissipative, relativistic mechanics. First, within a Minkowskian geometry, the basic properties of the proper time ${\tau}$ and the covariant velocity $u_{\mu}$ are recapitulated. Next, using a scalar function ${\psi}(x)$ and its negative derivatives ${\varphi}_{\mu}{^{\prime}}s$, we construct a covariant Lagrangian ${\Lambda}$ that generalizes the famous Bateman-Caldirola-Kanai Lagrangian of nonrelativistic frictional mechanics. Finally, we propose a deterministic model for ${\psi}$ (involving the drag coefficient A) whose explicit solution leads to relativistic damped Rayleigh motion in the rest frame of the medium.

Treatment of non-resonant spatial self-shielding effect of double heterogeneous region

  • Tae Young Han;Hyun Chul Lee
    • Nuclear Engineering and Technology
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    • v.55 no.2
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    • pp.749-755
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    • 2023
  • A new approximation method was proposed for treating the non-resonant spatial self-shielding effects of double heterogeneous region such as the double heterogeneous effect of VHTR fuel compact in the thermal energy range and that of BP compact with BISO. The method was developed based on the effective homogenization method and a spherical unit cell model with explicit coated layers and a matrix layer. The self-shielding factor was derived from the relation between the collision probabilities for a double heterogeneous compact and the effective cross section for the homogenized compact. First, the collision probabilities and transmission probabilities for all layers of the spherical model were calculated using conventional collision probability solver. Then, the effective cross section for the homogenized sphere cell representing the homogenized compact was obtained from the transmission probability calculated using the probability density function of a chord length. The verification calculations revealed that the proposed method can predict the self-shielding factor with a maximum error of 2.3% and the double heterogeneous effect with a maximum error of 200 pcm in the typical VHTR problems with various packing fractions and BP compact sizes.