Mathematical and Computer Modelling最新文献

The feasibility of applying rapid and non-destructive analysis based on Visible/ Near-Infrared Spectroscopy (VIS/NIR spectrometer) in detecting Malus Asiatica Nakai’s firmness during different shelf lives was discussed in this manuscript. Based on the best preprocessing technique found for each method, calibration models established by Partial Least-Square (PLS), Principal Component Regression (PCR), and Least Squares-Support Vector Machine (LS-SVM) were compared. The optimal models for firmness of Malus Asiatica Nakai were obtained by PLS with SNV as the best pretreatment. On the 1st day of shelf life, the correlation coefficients of prediction (Rp) and the Root-Mean-Square Errors of Prediction (RMSEP) were 0.7999 and 0.7994, respectively. On the 4th day of shelf life, the indexes were 0.7494 and 0.5856. But with the extension of shelf life, weightlessness rate of Malus Asiatica Nakai was reduced, the mealiness phenomenon became serious, quality had dropped sharply, hence the research of Malus Asiatica Nakai became insignificant. Results showed that, the potential of non-destructive measure for predicting accepted fruit parameters enabled the determination of optimum harvest date and fruit quality in different shelf lives.

In this paper, we consider two iterative algorithms for the Sylvester-conjugate matrix equation $AV+BW=E\overline{V}F+C$ and $AV+B\overline{W}=E\overline{V}F+C$. When these two matrix equations are consistent, for any initial matrices the solutions can be obtained within finite iterative steps in the absence of round off errors. Some lemmas and theorems are stated and proved where the iterative solutions are obtained. Two numerical examples are given to illustrate the effectiveness of the proposed method.

This paper proposes a developed bi-objective two-stage stochastic mixed-integer linear programming model for redesigning a reliable warehouse network. In this model, the warehouses capacity which should be phased out, remained, or relocated to other warehouses, and the shipment quantity of the product between the network nodes with a consideration for two delivery lead times is to be determined. Unlike most previous works, considering two delivery lead times, the maximum capacity for each warehouse location, reliability and uncertainty are taken into account in this study. The proposed bi-objective model includes: (1) minimizing average costs including the sum of fixed, production, transportation, relocation and capacity extension costs; (2) maximizing the coverage percentage of customer demand delivered within the preferred delivery lead time. In order to obtain Pareto optimal solutions, a novel version of $\epsilon$-constraint method (i.e., the augmented $\epsilon$-constraint) is applied. A real industrial case is applied to validate and verify the developed warehouse redesigning network model under reliability concept.

In this paper, we will employ some dynamic inequalities of Opial’s type on time scales to prove several results related to the spacing between consecutive zeros of a solution of a second order dynamic equation with a damping term. We also obtain several results related to the spacing between a zero of the solution and/or a zero of its derivative. As a special case, we will establish some new results for differential and difference equations with damping terms. For illustration, we will derive some well-known results obtained for differential equations without damping terms. The results yield conditions for disfocality and disconjugacy for dynamic equations with damping terms on time scales.

In this paper, the optimal homotopy asymptotic method (OHAM) and the traditional homotopy analysis method (HAM) are used to obtain analytical solution for a strongly nonlinear oscillation. Moreover, the homotopy-pade technique is employed to accelerate the convergence of solution series of traditional HAM. Results show that the second-order approximation by the OHAM is quick convergence and more accurate than the high-order of approximation by the homotopy-pade technique.

In this paper, we introduce viscosity approximation methods based on generalized contraction mappings for finding a set of common fixed points of a countable family of strict pseudo-contraction mappings, the common element of the set solutions of a general system of variational inequalities with Lipschitzian and relaxed cocoercive mappings and the set of solutions of a generalized mixed equilibrium problem. Furthermore, strong convergence theorems of the purposed iterative process are established in the framework of Banach spaces. The results presented in this paper improve and extend many recent important results.

This paper proposes a new complex-valued wavelet network based on Gabor transfer functions which have complex-valued weights, input/output variables and translation parameters. A learning algorithm is developed by using the technique of genetic algorithm to facilitate implementation of the network. The effectiveness of the proposed network is evaluated by applying the network to approximate several complicated nonlinear functions, and to tackle the 4-QAM (quadrature amplitude modulation) digital communications channel equalization and the image enhancement via feature extraction problems in signal processing. Indeed, the evaluation results obtained by testing the proposed wavelet network with real facial and textile fabric images clearly show that it is a very useful tool for solving problems in the field of complex-valued signal analysis.

An $m$-point boundary value problem with one-dimensional $p$-Laplacian at resonance on $[0,\infty )$ is considered. By establishing a continuation theorem and applying a suitable homotopy, Leray–Schauder degree, a priori estimate, the existence of solutions to the above problem is obtained.

In this paper, an analytical solution for boundary layer flow over a flat plate with slip flow and constant heat flux surface condition has been presented for the first time. The Navier–Stokes and energy equations are reduced by a similarity transform in order for a set of nonlinear ordinary differential equations to be formed. Then, governing equations will be solved analytically by using a kind of analytic technique for nonlinear problems which has been named the homotopy analysis method (HAM). The obtained results of this study have been compared with the results of differential quadrature method (DQM) as a promising numerical method. Very good agreement has been shown between analytical results and those obtained by DQ. Finally, effects of the Prandtl number and rarefaction parameter $K$ on velocity and temperature profiles are investigated.

In recent years, risk management and analysis has attracted a great deal of attention from both researchers and practitioners. Enterprise risk management has become an important topic in today’s more complex, interrelated global business environment, replete with threats from natural, political, economic, and technical sources. This survey and introductory article addresses computerized tools used for risk management and analysis. Risks are studied from perspectives of different disciplines, with a discussion of how various methods and tools are used to optimize risk management.