New Forward and Inverse Solutions for Wet Fins Generalized Profiles With All Nonlinear Phenomena

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Ranjan Das ◽  
Balaram Kundu

Abstract This study establishes forward closed-form and inverse analyses of wet fins of various profiles involving all modes of heat transfer. Existing limitations in the literature are addressed here by choosing the appropriate nonlinear variation of thermal conductivity and radiation effects. The error between linear and nonlinear methodologies is found to be within 60%. Furthermore, the maximum error between the closed-form solution based on the differential transformation method (DTM), and the numerical solution is observed as 0.5%. After necessary validations, optimization of various fin profiles is carried out by the maximization of the net fin heat transmission rate under a defined fin volume and thermogeometrical constraints. For the optimum criterion, the suitability of the artificial bee colony (ABC)-based metaheuristic technique is established. The identification of thermogeometrical parameters is realized by analyzing combinations obtained from 100 runs of ABC and the decision-making criterion is adopted on the basis of the maximum thermal performance. Among the studied profiles, concave parabolic geometry yields the maximum heat transport rate, which is followed by triangular, convex, and rectangular geometries for the same fin volume. The present combination of DTM and ABC techniques is proposed to be useful in practical applications toward design and the selection of evaporator fins for air-conditioning and refrigeration appliances operating under wet conditions in a more accurate and optimized manner.

2011 ◽  
Vol 89 (7) ◽  
pp. 761-767 ◽  
Author(s):  
H. Al-Qahtani ◽  
B.S. Yilbas

The wave nature of the heating model is considered, incorporating the Cattaneo equation with the presence of a volumetric heat source. The volumetric heat generation resembles the step input laser short-pulse intensity. The governing of the heat equation is solved analytically using the Laplace transformation method. The stress field generated due to thermal contraction and expansion of the substrate material is formulated and the closed-form solution is presented. It is found that the wave nature of the heating is dominant during the period of the irradiated short-pulse; however, in the late cooling period, the wave nature of heating is replaced by diffusional heat conduction, governed by Fourier’s law. The stress field during the heating cycle is compressive and becomes tensile in the cooling cycle.


2017 ◽  
Vol 15 (08) ◽  
pp. 1740008
Author(s):  
Francesco A. Raffa ◽  
Mario Rasetti

The unitary transformation method is utilized for the closed form solution of the nonlinear generalization of the Jaynes–Cummings (JC) model, which includes arbitrary multiphoton and intensity-dependent interactions between radiation and matter. Specifically, the unitary transformation leading to the diagonalization of the relevant Hamiltonian is established and energy levels and eigenstates are derived. It is also shown that the results for the JC model can be extended to the anti-Jaynes–Cummings (AJC) model through the map between the two models.


2013 ◽  
Vol 40 (2) ◽  
pp. 106-114
Author(s):  
J. Venetis ◽  
Aimilios (Preferred name Emilios) Sideridis

2021 ◽  
Vol 10 (7) ◽  
pp. 435
Author(s):  
Yongbo Wang ◽  
Nanshan Zheng ◽  
Zhengfu Bian

Since pairwise registration is a necessary step for the seamless fusion of point clouds from neighboring stations, a closed-form solution to planar feature-based registration of LiDAR (Light Detection and Ranging) point clouds is proposed in this paper. Based on the Plücker coordinate-based representation of linear features in three-dimensional space, a quad tuple-based representation of planar features is introduced, which makes it possible to directly determine the difference between any two planar features. Dual quaternions are employed to represent spatial transformation and operations between dual quaternions and the quad tuple-based representation of planar features are given, with which an error norm is constructed. Based on L2-norm-minimization, detailed derivations of the proposed solution are explained step by step. Two experiments were designed in which simulated data and real data were both used to verify the correctness and the feasibility of the proposed solution. With the simulated data, the calculated registration results were consistent with the pre-established parameters, which verifies the correctness of the presented solution. With the real data, the calculated registration results were consistent with the results calculated by iterative methods. Conclusions can be drawn from the two experiments: (1) The proposed solution does not require any initial estimates of the unknown parameters in advance, which assures the stability and robustness of the solution; (2) Using dual quaternions to represent spatial transformation greatly reduces the additional constraints in the estimation process.


Author(s):  
Puneet Pasricha ◽  
Anubha Goel

This article derives a closed-form pricing formula for the European exchange option in a stochastic volatility framework. Firstly, with the Feynman–Kac theorem's application, we obtain a relation between the price of the European exchange option and a European vanilla call option with unit strike price under a doubly stochastic volatility model. Then, we obtain the closed-form solution for the vanilla option using the characteristic function. A key distinguishing feature of the proposed simplified approach is that it does not require a change of numeraire in contrast with the usual methods to price exchange options. Finally, through numerical experiments, the accuracy of the newly derived formula is verified by comparing with the results obtained using Monte Carlo simulations.


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