Huang S.-M.,Dongguan University of Technology
International Journal of Thermal Sciences | Year: 2016
Membrane channels have been extensively used for air humidity control and energy recovery. The membranes are commonly parallel-plate type. However they probably are deformed because of their weak mechanical strengths and fluid pressure. Effects of the deformation heights (Δh) on the laminar flow and heat transfer in the plate membrane channels are studied based on two unit cells. Each one of them includes two neighboring membranes and a channel sandwiched by the membranes. The equations governing the momentum and heat transports are established together with a uniform wall temperature boundary condition and numerically solved by a finite volume approach. The mean (fRe) and Nusselt number (Num) are obtained. The influences of the deformation heights (Δh), aspect ratios (b/a), and Reynolds numbers (Re) on the (fRe)m and Num are calculated. It can be found that when the b/a is less than or equal to 25, the Num rises with the Δh increasing for the air channel. However the Num firstly rises, and then decreases with the Δh increasing when the b/a ranging from 30 to 40. For the water/LiCl solution channels, the Num for the LiCl solution is about 40%-56% larger than that for the water stream. © 2016 Elsevier Masson SAS. All rights reserved.
Yan X.,Dongguan University of Technology
International Journal of Control and Automation | Year: 2012
In this paper, we present an inventory model for perishable items with freshness-dependent demand rate and partial backlogging. Because the customers prefer to purchasing fresh items for given price, the demand rate is assumed to be decreasing in the age of the items. The existence and uniqueness of the optimal solution of the profit per unit time are examined although the profit function is not jointly concave. The results are illustrated through numerical example and sensitivity analysis is reported.
Yan X.,Dongguan University of Technology |
Wang Y.,Chongqing University
International Journal of Production Research | Year: 2014
We study a newsvendor problem with capital constraint and demand forecast update. The newsvendor has two instants to order from a supplier prior to a single selling season. While the demand is uncertain, the newsvendor can improve the forecast by utilizing the market signal observed between the first and second instants. We analyze the newsvendors optimal ordering policy in two cases: risk-neutrality and risk-aversion. Our analysis suggests that the optimal policy in each case is characterized by a critical value: A target safety capital. Under this policy, part of capital is left to use at instant 2 if and only if the initial capital is above the target safety capital. When this happens, the order quantity at instant 1 decreases as the initial capital increases. We further analyze the effect of information update on the newsvendors ordering policy. Our results indicate that more capital should be left to use at instant 2 when the correlation coefficient between market information and demand becomes large or when the newsvendor is more risk-averse. © 2014 Taylor & Francis.
Liu Q.,Dongguan University of Technology
Journal of Global Optimization | Year: 2013
In this paper, we discuss the performance of the DIRECT global optimization algorithm on problems with linear scaling. We show with computations that the performance of DIRECT can be affected by linear scaling of the objective function. We also provide a theoretical result which shows that DIRECT does not perform well when the absolute value of the objective function is large enough. Then we present DIRECT-a, a modification of DIRECT, to eliminate the sensitivity to linear scaling of the objective function. We prove theoretically that linear scaling of the objective function does not affect the performance of DIRECT-a. Similarly, we prove that some modifications of DIRECT are also unaffected by linear scaling of the objective function, while the original DIRECT algorithm is sensitive to linear scaling. Numerical results in this paper show that DIRECT-a is more robust than the original DIRECT algorithm, which support the theoretical results. Numerical results also show that careful choices of the parameter ε can help DIRECT perform well when the objective function is poorly linearly scaled. © 2012 Springer Science+Business Media, LLC.
Jian R.-Q.,Dongguan University of Technology
Letters in Mathematical Physics | Year: 2013
In this letter, we use quantum quasi-shuffle algebras to construct Rota-Baxter algebras, as well as tridendriform algebras. We also propose the notion of braided Rota-Baxter algebras, the relevant object of Rota-Baxter algebras in a braided tensor category. Examples of such new algebras are provided using quantum multi-brace algebras in a category of Yetter-Drinfeld modules. © 2013 Springer Science+Business Media Dordrecht.