Journal of Applied Mathematics
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The latest articles from Hindawi Publishing Corporation
© 2015 , Hindawi Publishing Corporation . All rights reserved.

Approximate Solutions of the Generalized Abel’s Integral Equations Using the Extension Khan’s Homotopy Analysis Transformation Method
Wed, 04 Mar 2015 09:34:27 +0000
http://www.hindawi.com/journals/jam/2015/357861/
User friendly algorithm based on the optimal homotopy analysis transform method
(OHATM) is proposed to find the approximate solutions to generalized Abel’s integral equations. The
classical theory of elasticity of material is modeled by the system of Abel integral equations. It is observed that
the approximate solutions converge rapidly to the exact solutions. Illustrative numerical examples are given
to demonstrate the efficiency and simplicity of the proposed method. Finally, several numerical examples are
given to illustrate the accuracy and stability of this method. Comparison of the approximate solution with the
exact solutions shows that the proposed method is very efficient and computationally attractive. We can use
this method for solving more complicated integral equations in mathematical physical.
Mohamed S. Mohamed, Khaled A. Gepreel, Faisal A. AlMalki, and Maha AlHumyani
Copyright © 2015 Mohamed S. Mohamed et al. All rights reserved.

Hyperelliptic Curves for the Vector Decomposition Problem over Fields of Even Characteristic
Wed, 04 Mar 2015 08:37:44 +0000
http://www.hindawi.com/journals/jam/2015/197097/
We present an infinite family of hyperelliptic curves of genus two over a finite field of even characteristic which are suitable for the vector decomposition problem.
Seungkook Park
Copyright © 2015 Seungkook Park. All rights reserved.

Dynamic Output Feedback Robust Model Predictive Control via Zonotopic SetMembership Estimation for Constrained QuasiLPV Systems
Tue, 03 Mar 2015 13:51:14 +0000
http://www.hindawi.com/journals/jam/2015/875850/
For the quasilinear parameter varying (quasiLPV) system with bounded disturbance, a synthesis approach of dynamic output feedback robust model predictive control (OFRMPC) is investigated. The estimation error set is represented by a zonotope and refreshed by the zonotopic setmembership estimation method. By properly refreshing the estimation error set online, the bounds of true state at the next sampling time can be obtained. Furthermore, the feasibility of the main optimization problem at the next sampling time can be determined at the current time. A numerical example is given to illustrate the effectiveness of the approach.
Xubin Ping and Ning Sun
Copyright © 2015 Xubin Ping and Ning Sun. All rights reserved.

On a Nonlinear Degenerate Evolution Equation with Nonlinear Boundary Damping
Tue, 03 Mar 2015 10:01:09 +0000
http://www.hindawi.com/journals/jam/2015/281032/
This paper deals essentially with a nonlinear degenerate evolution equation of the form supplemented with nonlinear boundary conditions of Neumann type given by . Under suitable conditions the existence and uniqueness of solutions are shown and that the boundary damping produces a uniform global stability of the corresponding solutions.
A. T. Lourêdo, G. Siracusa, and C. A. Silva Filho
Copyright © 2015 A. T. Lourêdo et al. All rights reserved.

Reliability Analysis in Presence of Random Variables and Fuzzy Variables
Mon, 02 Mar 2015 09:33:46 +0000
http://www.hindawi.com/journals/jam/2015/365051/
For mixed uncertainties of random variables and fuzzy variables in engineering, three indices, that is, interval reliability index, mean reliability index, and numerical reliability index, are proposed to measure safety of structure. Comparing to the reliability membership function for measuring the safety in case of mixed uncertainties, the proposed indices are more intuitive and easier to represent the safety degree of the engineering structure, and they are more suitable for the reliability design in the case of the mixed uncertainties. The differences and relations among three proposed indices are investigated, and their applicability is compared. Furthermore, a technique based on the probability density function evolution method is employed to improve the computational efficiency of the proposed indices. At last, a numerical example and two engineering examples are illustrated to demonstrate the feasibility, reasonability, and efficiency of the computational technique of the proposed indices.
Cui Lijie, Lü Zhenzhou, and Li Guijie
Copyright © 2015 Cui Lijie et al. All rights reserved.

Chinese Gini Coefficient from 2005 to 2012, Based on 20 Grouped Income Data Sets of Urban and Rural Residents
Mon, 02 Mar 2015 09:03:02 +0000
http://www.hindawi.com/journals/jam/2015/939020/
Data insufficiency has become the primary factor affecting research on income disparity in China. To resolve this issue, this paper explores Chinese income distribution and income inequality using distribution functions. First, it examines 20 sets of grouped data on family income between 2005 and 2012 by the China Yearbook of Household Surveys, 2013, and compares the fitting effects of eight distribution functions. The results show that the generalized beta distribution of the second kind has a high fitting to the income distribution of urban and rural residents in China. Next, these results are used to calculate the Chinese Gini ratio, which is then compared with the findings of relevant studies. Finally, this paper discusses the influence of urbanization on income inequality in China and suggests that accelerating urbanization can play an important role in narrowing the income gap of Chinese residents.
Jiandong Chen, Fuqian Fang, Wenxuan Hou, Fengying Li, Ming Pu, and Malin Song
Copyright © 2015 Jiandong Chen et al. All rights reserved.

Feng’s First Integral Method Applied to the ZKBBM and the Generalized Fisher SpaceTime Fractional Equations
Mon, 02 Mar 2015 07:38:30 +0000
http://www.hindawi.com/journals/jam/2015/191545/
The fractional derivatives in the sense of the modified RiemannLiouville derivative and Feng’s first integral method are employed to obtain the exact solutions of the nonlinear spacetime fractional ZKBBM equation and the nonlinear spacetime fractional generalized Fisher equation. The power of this manageable method is presented by applying it to the above equations. Our approach provides first integrals in polynomial form with high accuracy. Exact analytical solutions are obtained through establishing first integrals. The present method is efficient and reliable, and it can be used as an alternative to establish new solutions of different types of fractional differential equations applied in mathematical physics.
Huitzilin YépezMartínez, Ivan O. Sosa, and Juan M. Reyes
Copyright © 2015 Huitzilin YépezMartínez et al. All rights reserved.

Iterative Algorithms for Variational Inequalities Governed by Boundedly Lipschitzian and Strongly Monotone Operators
Sun, 01 Mar 2015 08:27:54 +0000
http://www.hindawi.com/journals/jam/2015/175254/
Consider the variational inequality of finding a point satisfying the property for all , where is a level set of a convex function defined on a real Hilbert space and is a boundedly Lipschitzian (i.e., Lipschitzian on bounded subsets of ) and strongly monotone operator. He and Xu proved that this variational inequality has a unique solution and devised iterative algorithms to approximate this solution (see He and Xu, 2009). In this paper, relaxed and selfadaptive iterative algorithms are proposed for computing this unique solution. Since our algorithms avoid calculating the projection (calculating by computing a sequence of projections onto halfspaces containing the original domain ) directly and select the stepsizes through a selfadaptive way (having no need to know any information of bounded Lipschitz constants of (i.e., Lipschitz constants on some bounded subsets of )), the implementations of our algorithms are very easy. The algorithms in this paper improve and extend the corresponding results of He and Xu.
Caiping Yang and Songnian He
Copyright © 2015 Caiping Yang and Songnian He. All rights reserved.

A FloatPath Theory and Its Application to the TimeCost Tradeoff Problem
Thu, 26 Feb 2015 08:41:19 +0000
http://www.hindawi.com/journals/jam/2015/539374/
Activity floats are vital for project scheduling, such as total floats which determine the maximum permissible delays of activities. Moreover, activity paths in activity networks present essences of many project scheduling problems; for example, the timecost tradeoff is to shorten long paths at lower costs. We discovered relationships between activity floats and paths and established a floatpath theory. The theory helps to compute path lengths using activity floats and analyze activity floats using paths, which helps to transmute a problem into the other simpler one. We discussed applications of the floatpath theory and applied it to solve the timecost tradeoff problem (TCTP), especially the nonlinear and discrete versions. We proposed a simplification from an angle of path as a preprocessing technique for the TCTP. The simplification is a difficult path problem, but we transformed it into a simple float problem using the floatpath theory. We designed a polynomial algorithm for the simplification, and then the TCTP may be solved more efficiently.
Zhixiong Su, Jianxun Qi, and Hanying Wei
Copyright © 2015 Zhixiong Su et al. All rights reserved.

Stability Results for an AgeStructured SIS Epidemic Model with Vector Population
Tue, 24 Feb 2015 14:52:29 +0000
http://www.hindawi.com/journals/jam/2015/838312/
We formulate an agestructured SIS epidemic model with periodic parameters, which includes host population and vector population. The host population is described by two partial differential equations, and the vector population is described by a single ordinary differential equation. The existence problem for endemic periodic solutions is reduced to a fixed point problem of a nonlinear integral operator acting on locally integrable periodic functions. We obtain that if the spectral radius of the Fréchet derivative of the fixed point operator at zero is greater than one, there exists a unique endemic periodic solution, and we investigate the global attractiveness of diseasefree steady state of the normalized system.
HeLong Liu, JingYuan Yu, and GuangTian Zhu
Copyright © 2015 HeLong Liu et al. All rights reserved.

Generalized WellPosedness for Symmetric Vector QuasiEquilibrium Problems
Tue, 24 Feb 2015 09:08:34 +0000
http://www.hindawi.com/journals/jam/2015/108357/
We introduce and study wellposedness in connection with the symmetric vector quasiequilibrium problem, which unifies its Hadamard and LevitinPolyak wellposedness. Using the nonlinear scalarization function, we give some sufficient conditions to guarantee the existence of wellposedness for the symmetric vector quasiequilibrium problem.
Weibing Zhang, Nanjing Huang, and Donal O’Regan
Copyright © 2015 Weibing Zhang et al. All rights reserved.

Infinitely Many Eigenfunctions for Polynomial Problems: Exact Results
Mon, 23 Feb 2015 07:24:38 +0000
http://www.hindawi.com/journals/jam/2015/516159/
Let be a realvalued polynomial function in which the degree of in is greater than or equal to 1. For any polynomial , we assume that is a nonlinear operator with . In this paper, we will find an eigenfunction to satisfy the following equation: for some eigenvalue and we call the problem a fixed point like problem. If the number of all eigenfunctions in is infinitely many, we prove that (i) any coefficients of , are all constants in and (ii) is an eigenfunction in if and only if .
YiChou Chen
Copyright © 2015 YiChou Chen. All rights reserved.

Computing Assortative Mixing by Degree with the Metric in Networks Using Linear Programming
Sun, 22 Feb 2015 15:46:34 +0000
http://www.hindawi.com/journals/jam/2015/580361/
Calculation of assortative mixing by degree in networks indicates whether nodes with similar degree are connected to each other. In networks with scalefree distribution high values of assortative mixing by degree can be an indication of a hublike core in networks. Degree correlation has generally been used to measure assortative mixing of a network. But it has been shown that degree correlation cannot always distinguish properly between different networks with nodes that have the same degrees. The socalled metric has been shown to be a better choice to calculate assortative mixing. The metric is normalized with respect to the class of networks without selfloops, multiple edges, and multiple components, while degree correlation is always normalized with respect to unrestricted networks, where selfloops, multiple edges, and multiple components are allowed. The challenge in computing the normalized metric is in obtaining the minimum and maximum value within a specific class of networks. We show that this can be solved by using linear programming. We use Lagrangian relaxation and the subgradient algorithm to obtain a solution to the metric problem. Several examples are given to illustrate the principles and some simulations indicate that the solutions are generally accurate.
Lourens J. Waldorp and Verena D. Schmittmann
Copyright © 2015 Lourens J. Waldorp and Verena D. Schmittmann. All rights reserved.

Fixed Point Approximation for Asymptotically Nonexpansive Type Mappings in Uniformly Convex Hyperbolic Spaces
Sun, 22 Feb 2015 15:32:27 +0000
http://www.hindawi.com/journals/jam/2015/510798/
We use a modified Siterative process to prove some strong and convergence results for asymptotically nonexpansive type mappings in uniformly convex hyperbolic spaces, which includes Banach spaces and CAT(0) spaces. Thus, our results can be viewed as extension and generalization of several known results in Banach spaces and CAT(0) spaces (see, e.g., Abbas et al. (2012), Abbas et al. (2013), Bruck et al. (1993), and Xin and Cui (2011)) and improve many results in the literature.
Shin Min Kang, Samir Dashputre, Bhuwan Lal Malagar, and Young Chel Kwun
Copyright © 2015 Shin Min Kang et al. All rights reserved.

On a System of Equations of a NonNewtonian Micropolar Fluid
Thu, 19 Feb 2015 15:28:55 +0000
http://www.hindawi.com/journals/jam/2015/481754/
We investigate a problem for a model of a nonNewtonian micropolar fluid coupled system. The problem has been considered in a bounded, smooth domain of with Dirichlet boundary conditions. The operator stress tensor is given by . To prove the existence of weak solutions we use the method of FaedoGalerkin and compactness arguments. Uniqueness and periodicity of solutions are also considered.
G. M. de Araújo, M. A. F. de Araújo, and E. F. L. Lucena
Copyright © 2015 G. M. de Araújo et al. All rights reserved.

Offline Model Predictive Control Based on Weighted Projection over Polytopes
Wed, 18 Feb 2015 08:42:48 +0000
http://www.hindawi.com/journals/jam/2015/741348/
This work presents a novel offline model predictive control technique for tracking of constrained systems. The quadratic programming problem, commonly found in constrained control methods, is replaced by sequential offline set projections based on priority given to the decision variables. If a preference is established in terms of which decision variables are more desirable, the optimization problem can be solved by sequentially choosing the most important variables and performing a membership test with the projection of the constraint closed set over the related dimensions. Thus, realtime optimization is replaced by offline projection operations and online onedimensional membership tests. This concept of decision variable prioritization is then applied to a form of model predictive control: feasible target tracking. Three quadratic programming problems are replaced by the proposed method. In the first problem, attainable steadystate demands are computed based on the performance of the plant. The reachable target command is then filtered in terms of dynamic admissibility, creating feasible inputs to the plant. Finally, the control is computed considering the current state and disturbance vectors along with the feasible and attainable command. Simulations of the method executing a pathfollowing task are presented, demonstrating its benefits with negligible online computational burden.
Fabio Andrade de Almeida
Copyright © 2015 Fabio Andrade de Almeida. All rights reserved.

Degeneralization Algorithm for Generation of Büchi Automata Based on Contented Situation
Tue, 10 Feb 2015 08:54:45 +0000
http://www.hindawi.com/journals/jam/2015/516104/
We present onthefly degeneralization algorithm used to transform generalized Büchi automata (GBA) into Büchi Automata (BA) different from the standard degeneralization algorithm. Contented situation, which is used to record what acceptance conditions are satisfiable during expanding LTL formulae, is attached to the states and transitions in the BA. In order to get the deterministic BA, the Shannon expansion is used recursively when we expand LTL formulae by applying the tableau rules. Onthefly degeneralization algorithm is carried out in each step of the expansion of LTL formulae. Ordered binary decision diagrams are used to represent the BA and simplify LTL formulae. The temporary automata are stored as syntax directed acyclic graph in order to save storage space. These ideas are implemented in a conversion algorithm used to build a property automaton corresponding to the given LTL formulae. We compare our method to previous work and show that it is more efficient for four sets of random formulae generated by LBTT.
Laixiang Shan, Jun Qin, Mingshi Chen, and Zheng Qin
Copyright © 2015 Laixiang Shan et al. All rights reserved.

Adaptive TimeStepping Using Control Theory for the Chemical Langevin Equation
Mon, 09 Feb 2015 09:51:48 +0000
http://www.hindawi.com/journals/jam/2015/567275/
Stochastic modeling of biochemical systems has been the subject of intense research in recent years due to the large
number of important applications of these systems. A critical stochastic model of wellstirred biochemical systems in
the regime of relatively large molecular numbers, far from the thermodynamic limit, is the chemical Langevin equation.
This model is represented as a system of stochastic differential equations, with multiplicative and noncommutative
noise. Often biochemical systems in applications evolve on multiple timescales; examples include slow transcription
and fast dimerization reactions. The existence of multiple timescales leads to mathematical stiffness, which is a major
challenge for the numerical simulation. Consequently, there is a demand for efficient and accurate numerical methods to
approximate the solution of these models. In this paper, we design an adaptive timestepping method, based on control
theory, for the numerical solution of the chemical Langevin equation. The underlying approximation method is the
Milstein scheme. The adaptive strategy is tested on several models of interest and is shown to have improved efficiency
and accuracy compared with the existing variable and constantstep methods.
Silvana Ilie and Monjur Morshed
Copyright © 2015 Silvana Ilie and Monjur Morshed. All rights reserved.

An Introduction to Fuzzy Testing of Multialternative Hypotheses for Group of Samples with the Single Parameter: Through the Fuzzy Confidence Interval of Region of Acceptance
Sun, 08 Feb 2015 11:12:53 +0000
http://www.hindawi.com/journals/jam/2015/365304/
Classical statistics and many data mining methods rely on “statistical significance” as a sole criterion for evaluating alternative hypotheses. It is very useful to find out the significant difference existing between the samples as well as the population or between two samples. But in this paper, the researchers try to apply the concepts of fuzzy group testing of hypothesis problem between multi group of samples of same size or different, through comparing the parameters like mean, standard deviation, and so forth. Hence we can compare multigroups such that they have the significant difference in their mean or standard deviation or other parameters through the fuzzy group testing of multihypotheses. The authors introduced and investigated the concepts very first time through fuzzy analysis that can decide which group(s) or samples can be taken for further investigation and either is rejected or accepted and hence the next discussion provides the properties of group of samples which may result in the optimized solution for the problem.
Manikandan Harikrishnan, Jeyabharathi Sundarrajan, and Muthuraj Rengasamy
Copyright © 2015 Manikandan Harikrishnan et al. All rights reserved.

Multiobjective Optimization Method Based on Adaptive Parameter Harmony Search Algorithm
Thu, 05 Feb 2015 09:13:46 +0000
http://www.hindawi.com/journals/jam/2015/165601/
The present trend in industries is to improve the techniques currently used in design and manufacture of products in order to meet the challenges of the competitive market. The crucial task nowadays is to find the optimal design and machining parameters so as to minimize the production costs. Design optimization involves more numbers of design variables with multiple and conflicting objectives, subjected to complex nonlinear constraints. The complexity of optimal design of machine elements creates the requirement for increasingly effective algorithms. Solving a nonlinear multiobjective optimization problem requires significant computing effort. From the literature it is evident that metaheuristic algorithms are performing better in dealing with multiobjective optimization. In this paper, we extend the recently developed parameter adaptive harmony search algorithm to solve multiobjective design optimization problems using the weighted sum approach. To determine the best weightage set for this analysis, a performance index based on least average error is used to determine the index of each weightage set. The proposed approach is applied to solve a biobjective design optimization of disc brake problem and a newly formulated biobjective design optimization of helical spring problem. The results reveal that the proposed approach is performing better than other algorithms.
P. Sabarinath, M. R. Thansekhar, and R. Saravanan
Copyright © 2015 P. Sabarinath et al. All rights reserved.

Epidemic Models with Immunization and Mutations on a Finite Population
Thu, 05 Feb 2015 07:56:30 +0000
http://www.hindawi.com/journals/jam/2015/239767/
We propose two variants of a stochastic epidemic model in which the disease is spread by mobile particles performing random walks on the complete graph. For the first model, we study the effect on the epidemic size of an immunization mechanism that depends on the activity of the disease. In the second model, the transmission agents can gain lives at random during their existences. We prove limit theorems for the final outcome of these processes. The epidemic model with mutations exhibits phase transition, meaning that if the mutation parameter is sufficiently large, then asymptotically all the individuals in the population are infected.
Elcio Lebensztayn
Copyright © 2015 Elcio Lebensztayn. All rights reserved.

Unconditional Positive Stable Numerical Solution of Partial Integrodifferential Option Pricing Problems
Wed, 04 Feb 2015 13:45:08 +0000
http://www.hindawi.com/journals/jam/2015/960728/
This paper is concerned with the numerical solution of partial integrodifferential equation for
option pricing models under a tempered stable
process known as CGMY model. A double
discretization finite difference scheme is used for the treatment
of the unbounded nonlocal integral term. We also introduce in the
scheme the Patankartrick to guarantee unconditional nonnegative
numerical solutions. Integration formula of open type is used in
order to improve the accuracy of the approximation of the integral
part. Stability and consistency are also studied. Illustrative examples are included.
M. Fakharany, R. Company, and L. Jódar
Copyright © 2015 M. Fakharany et al. All rights reserved.

On Fuzzy Solutions for Diffusion Equation
Sat, 31 Jan 2015 16:59:00 +0000
http://www.hindawi.com/journals/jam/2015/874931/
Our main goal is to define a fuzzy solution for problems involving diffusion. To this end, the solution of fuzzy diffusionreactionadvection equation will be defined as Zadeh’s extension of deterministic solution of the associated problem. Important aspects such as unity and stability of these solutions will also be studied. Graphical representations of these solutions will be presented.
Jefferson Leite, Moiseis Cecconello, Jackellyne Leite, and R. C. Bassanezi
Copyright © 2015 Jefferson Leite et al. All rights reserved.

Almost Periodic Time Scales and Almost Periodic Functions on Time Scales
Thu, 29 Jan 2015 14:23:47 +0000
http://www.hindawi.com/journals/jam/2015/730672/
We propose some new concepts of almost periodic time scales and almost periodic functions on time scales and give some basic properties of these new types of almost periodic time scales and almost periodic functions on time scales. We also give some comments on a recent paper by Wang and Agarwal (2014) concerning a new almost periodic time scale.
Yongkun Li and Bing Li
Copyright © 2015 Yongkun Li and Bing Li. All rights reserved.

Shear Current Effects on Monochromatic Water Waves Crossing Trenches
Thu, 29 Jan 2015 13:32:21 +0000
http://www.hindawi.com/journals/jam/2015/256084/
The reflection coefficients of monochromatic water waves over trenches with shear current are estimated analytically. The diffraction of waves by an abrupt depth change and shear current is formulated by the matched eigenfunction expansion method. The proper number of steps and evanescent modes are proposed by a series of convergence tests. The accuracy of the predicted reflection coefficients is checked by estimating the wave energy. Reflection and transmission characteristics are studied for various shear current conditions. The different combinations of strength, width of shear current, and incident wave angle with constant water depth topography are examined. The optimal figure of the trench with shear current is obtained by estimating the reflection coefficients for various sloped transitions. The resonant reflection of the water waves is found by multiarrayed optimal trenches and the interaction of sinusoidally varying topography with shear current.
JunWhan Lee, KooYong Park, and YongSik Cho
Copyright © 2015 JunWhan Lee et al. All rights reserved.

A Filled Function Method Dominated by Filter for Nonlinearly Global Optimization
Wed, 28 Jan 2015 16:47:11 +0000
http://www.hindawi.com/journals/jam/2015/245427/
This work presents a filled function method based on the filter technique for global optimization. Filled function method is one of the effective methods for nonlinear global optimization, since it can effectively find a better minimizer. Filter technique is applied to local optimization methods for its excellent numerical results. In order to optimize the filled function method, the filter method is employed for global optimizations in this method. A new filled function is proposed first, and then the algorithm and its properties are proved. The numerical results are listed at the end.
Wei Wang, Xiaoshan Zhang, and Min Li
Copyright © 2015 Wei Wang et al. All rights reserved.

An Empirical Study of Hybrid DEA and Grey System Theory on Analyzing Performance: A Case from Indian Mining Industry
Tue, 27 Jan 2015 12:36:50 +0000
http://www.hindawi.com/journals/jam/2015/395360/
India, which has long been recognized as a wellendowed nation in natural mineral resources, is a major minerals producer. According to the report of Indian Ministry of Mines 2013, Indian mining and metals sector ranked the fourth among the mineral producer countries, behind China, United States, and Russia and had in fact led the economy into recovery from the global financial crisis. Since this industry has turned into a significant issue, this paper attempts to rank the performance of 23 Indian mining and metal companies and to evaluate and measure the productivity change of these sectors during different time periods (2010–2014). Besides, the authors would like to choose one advanced model of MPI to see the performance of these companies in the pastpresent period and the 4year future period (2015–2018) by using forecasting results of Grey system theory. The results revealed that from the past to future period the National Mineral Development Corporation, Hindalco Industries Limited, and Coal India always keep their highest best rankings among 23 DMUs regarding performance scores. This study contributes better insights of Indian mining industry as it is the core of the economy.
LaiWang Wang, ThanhTuyen Tran, and NhuTy Nguyen
Copyright © 2015 LaiWang Wang et al. All rights reserved.

Simulation and Modeling of Flow in a Gas Compressor
Wed, 21 Jan 2015 06:32:50 +0000
http://www.hindawi.com/journals/jam/2015/682469/
The presented research demonstrates the results of a series of numerical simulations of gas flow through a singlestage centrifugal compressor with a vaneless diffuser. Numerical results were validated with experiments consisting of eight regimes with different mass flow rates. The steadystate and unsteady simulations were done in ANSYS FLUENT 13.0 and NUMECA FINE/TURBO 8.9.1 for oneperiod geometry due to periodicity of the problem. Firstorder discretization is insufficient due to strong dissipation effects. Results obtained with secondorder discretization agree with the experiments for the steadystate case in the region of high mass flow rates. In the area of low mass flow rates, nonstationary effects significantly influence the flow leading stationary model to poor prediction. Therefore, the unsteady simulations were performed in the region of low mass flow rates. Results of calculation were compared with experimental data. The numerical simulation method in this paper can be used to predict compressor performance.
Anna Avramenko, Alexey Frolov, and Jari Hämäläinen
Copyright © 2015 Anna Avramenko et al. All rights reserved.

Nonlinearities Distribution Homotopy Perturbation Method Applied to Solve Nonlinear Problems: ThomasFermi Equation as a Case Study
Tue, 20 Jan 2015 14:26:16 +0000
http://www.hindawi.com/journals/jam/2015/405108/
We propose an approximate solution of TF equation, obtained by using the nonlinearities distribution homotopy perturbation method (NDHPM). Besides, we show a table of comparison, between this proposed approximate solution and a numerical of TF, by establishing the accuracy of the results.
U. FilobelloNino, H. VazquezLeal, K. Boubaker, A. SarmientoReyes, A. PerezSesma, A. DiazSanchez, V. M. JimenezFernandez, J. CervantesPerez, J. SanchezOrea, J. HuertaChua, L. J. MoralesMendoza, M. GonzalezLee, C. HernandezMejia, and F. J. GonzalezMartinez
Copyright © 2015 U. FilobelloNino et al. All rights reserved.

Data Transformation Technique to Improve the Outlier Detection Power of Grubbs’ Test for Data Expected to Follow Linear Relation
Wed, 14 Jan 2015 11:17:44 +0000
http://www.hindawi.com/journals/jam/2015/708948/
Grubbs test (extreme studentized deviate test, maximum normed residual test) is used in various fields to identify outliers in a data set, which are ranked in the order of . However, ranking of data eliminates the actual sequence of a data series, which is an important factor for determining outliers in some cases (e.g., time series). Thus in such a data set, Grubbs test will not identify outliers correctly. This paper introduces a technique for transforming data from sequence bound linear form to sequence unbound form . Applying Grubbs test to the new transformed data set detects outliers more accurately. In addition, the new technique improves the outlier detection capability of Grubbs test. Results show that, Grubbs test was capable of identifing outliers at significance level 0.01 after transformation, while it was unable to identify those prior to transforming at significance level 0.05.
K. K. L. B. Adikaram, M. A. Hussein, M. Effenberger, and T. Becker
Copyright © 2015 K. K. L. B. Adikaram et al. All rights reserved.