Some New Subclasses of Nonsingular H-matrices
In this paper, we obtain some new subclasses of non¬singular H-matrices by using a diagonally dominant matrix
H-matrix, diagonal dominance, a diagonally dominant matrix.
Parallel Alternating Two-stage Methods for Solving Linear System
In this paper, we present parallel alternating two-stage methods for solving linear system Ax = b, where A is a monotone matrix or an H-matrix. And we give some convergence results of these methods for nonsingular linear system.
Parallel, alternating two-stage, convergence, linear system.
Some Results on Parallel Alternating Methods
In this paper, we investigate two parallel alternating methods for solving the system of linear equations Ax = b and give convergence theorems for the parallel alternating methods when the coefficient matrix is a nonsingular H-matrix. Furthermore, we give one example to show our results.
Nonsingular H-matrix, parallel alternating method, convergence.
Parallel Multisplitting Methods for Singular Linear Systems
In this paper, we discuss convergence of the extrapolated iterative methods for linear systems with the coefficient matrices are singular H-matrices. And we present the sufficient and necessary conditions for convergence of the extrapolated iterative methods. Moreover, we apply the results to the GMAOR methods. Finally, we give one numerical example.
Singular H-matrix, linear systems, extrapolated iterative method, GMAOR method, convergence.
A New Preconditioned AOR Method for Z-matrices
In this paper, we present a preconditioned AOR-type iterative method for solving the linear systems Ax = b, where A is a Z-matrix. And give some comparison theorems to show that the rate of convergence of the preconditioned AOR-type iterative method is faster than the rate of convergence of the AOR-type iterative method.
Z-matrix, AOR-type iterative method, precondition, comparison.
Electrical Performance of a Solid Oxide Fuel Cell Unit with Non-Uniform Inlet Flow and High Fuel Utilization
This study investigates the electrical performance of a
planar solid oxide fuel cell unit with cross-flow configuration when the fuel utilization gets higher and the fuel inlet flow are non-uniform.
A software package in this study solves two-dimensional,
simultaneous, partial differential equations of mass, energy, and
electro-chemistry, without considering stack direction variation. The
results show that the fuel utilization increases with a decrease in the molar flow rate, and the average current density decreases when the
molar flow rate drops. In addition, non-uniform Pattern A will induce more severe happening of non-reaction area in the corner of the fuel
exit and the air inlet. This non-reaction area deteriorates the average
current density and then deteriorates the electrical performance to –7%.
Performance, Solid oxide fuel cell, non-uniform, fuelutilization
Convergence Analysis of the Generalized Alternating Two-Stage Method
In this paper, we give the generalized alternating twostage method in which the inner iterations are accomplished by a generalized alternating method. And we present convergence results of the method for solving nonsingular linear systems when the coefficient matrix of the linear system is a monotone matrix or an H-matrix.
Generalized alternating two-stage method, linear system, convergence.
Some Results on Parallel Alternating Two-stage Methods
In this paper, we present parallel alternating two-stage
methods for solving linear system Ax=b, where A is a symmetric
positive definite matrix. And we give some convergence results of
these methods for nonsingular linear system.
alternating two-stage, convergence, linear system,parallel.
Optimization of Three-dimensional Electrical Performance in a Solid Oxide Fuel Cell Stack by a Neural Network
By the application of an improved back-propagation
neural network (BPNN), a model of current densities for a solid oxide
fuel cell (SOFC) with 10 layers is established in this study. To build
the learning data of BPNN, Taguchi orthogonal array is applied to
arrange the conditions of operating parameters, which totally 7 factors
act as the inputs of BPNN. Also, the average current densities
achieved by numerical method acts as the outputs of BPNN.
Comparing with the direct solution, the learning errors for all learning
data are smaller than 0.117%, and the predicting errors for 27
forecasting cases are less than 0.231%. The results show that the
presented model effectively builds a mathematical algorithm to predict
performance of a SOFC stack immediately in real time.
Also, the calculating algorithms are applied to proceed with the
optimization of the average current density for a SOFC stack. The
operating performance window of a SOFC stack is found to be
between 41137.11 and 53907.89. Furthermore, an inverse predicting
model of operating parameters of a SOFC stack is developed here by
the calculating algorithms of the improved BPNN, which is proved to
effectively predict operating parameters to achieve a desired
performance output of a SOFC stack.
a SOFC stack, BPNN, inverse predicting model of
operating parameters, optimization of the average current density
Some New Upper Bounds for the Spectral Radius of Iterative Matrices
In this paper, we present some new upper bounds for
the spectral radius of iterative matrices based on the concept of
doubly α diagonally dominant matrix. And subsequently, we give
two examples to show that our results are better than the earlier ones.
doubly α diagonally dominant matrix, eigenvalue,iterative matrix, spectral radius, upper bound.
Some Results on New Preconditioned Generalized Mixed-Type Splitting Iterative Methods
In this paper, we present new preconditioned generalized mixed-type splitting (GMTS) methods for solving weighted linear least square problems. We compare the spectral radii of the iteration matrices of the preconditioned and the original methods. The comparison results show that the preconditioned GMTS methods converge faster than the GMTS method whenever the GMTS method is convergent. Finally, we give a numerical example to confirm our theoretical results.
Preconditioned, GMTS method, linear system, convergence, comparison.
Some Results on Preconditioned Modified Accelerated Overrelaxation Method
In this paper, we present new preconditioned modified accelerated overrelaxation (MAOR) method for solving linear systems. We compare the spectral radii of the iteration matrices of the preconditioned and the original methods. The comparison results show that the preconditioned MAOR method converges faster than the MAOR method whenever the MAOR method is convergent. Finally, we give one numerical example to confirm our theoretical results.
preconditioned, MAOR method, linear system, convergence, comparison.
Preconditioned Generalized Accelerated Overrelaxation Methods for Solving Certain Nonsingular Linear System
In this paper, we present preconditioned generalized
accelerated overrelaxation (GAOR) methods for solving certain
nonsingular linear system. We compare the spectral radii of the
iteration matrices of the preconditioned and the original methods. The
comparison results show that the preconditioned GAOR methods
converge faster than the GAOR method whenever the GAOR method
is convergent. Finally, we give two numerical examples to confirm our
Preconditioned, GAOR method, linear system, convergence, comparison.
Proxisch: An Optimization Approach of Large-Scale Unstable Proxy Servers Scheduling
Nowadays, big companies such as Google, Microsoft,
which have adequate proxy servers, have perfectly implemented
their web crawlers for a certain website in parallel. But due to
lack of expensive proxy servers, it is still a puzzle for researchers
to crawl large amounts of information from a single website in
parallel. In this case, it is a good choice for researchers to use
free public proxy servers which are crawled from the Internet. In
order to improve efficiency of web crawler, the following two issues
should be considered primarily: (1) Tasks may fail owing to the
instability of free proxy servers; (2) A proxy server will be blocked
if it visits a single website frequently. In this paper, we propose
Proxisch, an optimization approach of large-scale unstable proxy
servers scheduling, which allow anyone with extremely low cost to
run a web crawler efficiently. Proxisch is designed to work efficiently
by making maximum use of reliable proxy servers. To solve second
problem, it establishes a frequency control mechanism which can
ensure the visiting frequency of any chosen proxy server below the
website’s limit. The results show that our approach performs better
than the other scheduling algorithms.
Proxy server, priority queue, optimization approach,
distributed web crawling.
Simulation on Fuel Metering Unit Used for TurboShaft Engine Model
Fuel Metering Unit (FMU) in fuel system of an aeroengine sometimes has direct influence on the engine performance, which is neglected for the sake of easy access to mathematical model of the engine in most cases. In order to verify the influence of FMU on an engine model, this paper presents a co-simulation of a stepping motor driven FMU (digital FMU) in a turboshaft aeroengine, using AMESim and MATLAB to obtain the steady and dynamic characteristics of the FMU. For this method, mechanical and hydraulic section of the unit is modeled through AMESim, while the stepping motor is mathematically modeled through MATLAB/Simulink. Combining these two sub-models yields an AMESim/MATLAB co-model of the FMU. A simplified component level model for the turboshaft engine is established and connected with the FMU model. Simulation results on the full model show that the engine model considering FMU characteristics describes the engine more precisely especially in its transition state. An FMU dynamics will cut down the rotation speed of the high pressure shaft and the inlet pressure of the combustor during the step response. The work in this paper reveals the impact of FMU on engine operation characteristics and provides a reference to an engine model for ground tests.
Fuel metering unit, stepping motor, AMESim/MATLAB, full digital simulation.