ADVANCES IN MATHEMATICAL MODELING
Year:2015 | Volume:5 | Issue:1|Papers Count:6

This paper was devoted to numerical solution of capillary formation in tumor angiogenesis with time fractional derivative. A time discretization approach based on the q-weighted fractional finite difference scheme was employed for time fractional derivative and a mesh free process was applied by using radial basis functions (RBFs). Stability analysis of the method was also investigated and some numerical cases were studied.

Censored samples are discussed in experiments of life-testing; i.e. whenever the experimenter does not observe the failure times of all units placed on a life test. In recent years, inference based on censored sampling is considered, so that about the parameters of various distributions such as, normal, exponential, gamma, Rayleigh, Weibull, log normal, inverse Gaussian, logistic, Laplace, and Pareto, has been inferred based on censored sampling. In this paper, a generalization of the progressive joint Type-II censoring scheme is introduced. Application of this scheme is in the case that the lifetimes of first units of two samples are missing or lost and also because of preventing of long time of the test, some units are removed during the test. After introducing the scheme, for parameters of two Weibull populations, maximum likelihood estimators and confidence interval using procedures such as asymptotic normality and bootstrap methods, under the scheme, are obtained. Finally, by means a simulation study these estimations are evaluated and also all confidence intervals are compared in terms of coverage probabilities.

One key issue in the theory of the OWA operator is to determine its associated weights. In this paper, based upon the M-Entropy measures, new models for obtaining the ordered weighted averaging (OWA) operators are proposed. In the models it is assumed, according to available information that the OWA weights are in decreasing or increasing order. Some properties of the models are analyzed and the method of Lagrange multipliers is used to provide a direct way to find these weights. The models are solved with specific level of Orness comparing the results with some other related models and with the other maximum M-entropy model. The results demonstrate the efficiency of the M-Entropy models in generating the OWA operator weights. Also, the obtained weights of the two M-entropy models confirm the difference between two types of the models. Finally, an applied example is presented to illustrate the applications of the proposed model.

The drainage length can be artificially decreased using vertical drains where need to accelerate in the consolidation settlement, so that the flow can be drained radially and vertically. In this research, the three dimensional consolidation equation with appropriate boundary conditions was used in cylindrical coordinates, and then was solved analytically. After the analytical solution, analysis of the results was done on using MATLAB software. Moreover, the average degree of consolidation versus time was obtained and compared with the results of one-dimensional method. Findings showed that, the analytical method in this research is in accordance with another numerical method in the previous researches.

In studying some phenomena, the researchers are usually encountered with data that are not Euclidean in nature. To investigate the properties of these data, it is required to use some new statistical tools. Statistical methods to analysis these typical data are called non-linear statistics. Circular statistics is an example of this field. After explaining some circular distributions that are able to model skew circular data, probabilistic modeling of wind direction data related to meteorological stations of Kurdistan province is studied in this paper.

This study investigates the natural convection heat transfer in a horizontal annulus with discrete heating using a mesh-free lattice Boltzmann method. The lattice Boltzmann method has become an alternative to the conventional computational fluid dynamics methods for simulation of complex fluid flows. The major advantages of the lattice Boltzmann method are the explicit feature of the governing equation, easy for parallel computation, and simple implementation of boundary conditions on curved boundaries. Despite well viability of standard LBM for the uniform mesh, it cannot be directly applied to problems with complex geometry and non-uniform mesh. An efficient method for removing this limitation is to use Taylor series expansion and least squares-based LBM (TLLBM). The final form of the TLLBM is an algebraic formulation with no limitation on the mesh structure. This method can also be applied to any lattice velocity model. In the present work, the TLLBM with D2Q9 lattice model is used to simulate natural convection heat transfer in a horizontal annulus with discrete heating. The effects of Rayleigh number and different arrangement of two heat source-sink pairs on the fluid flow and heat transfer characteristics are investigated.