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This paper presents a new calibration procedure to identify the geometric parameters which improve the kinematic model accuracy of a mechanism. This procedure has been applied to a 2-DOF spatial parallel mechanism, obtaining the identified parameters by means of the direct kinematic model and reducing the position error of the moving platform. Data acquisition is performed by measuring three standard spheres, fixed to the moving platform, by means of a coordinate measuring machine. The method implemented defines an objective function which is optimized though a numerical method based on the Levenberg-Marquardt algorithm. This function compares the measured and calculated moving platform coordinates and minimizes this difference. Results show that in both cases, identification and test position, the position error is reduced considerably. The method developed can be easily generalized to other parallel mechanism. [ABSTRACT FROM AUTHOR]

In the paper we test robustness of particular dynamic systems in a compact regions of a plane and a weak structural stability of one dynamic system of high order in a compact region of its phase space. The test was carried out based on the fundamental theory of dynamical systems on a plane and based on the conditions for weak structural stability of high order dynamic systems. A numerical algorithm for testing the weak structural stability of high order dynamic systems has been proposed. Based on this algorithm we assess the weak structural stability of one computable general equilibrium model. [ABSTRACT FROM AUTHOR]

This paper analyzes the effectiveness of various monotonic discretizations of an ODE in a parameter range reduction algorithm by considering the resulting ranges for the parameter λ obtained from the simple model x′ = λx. [ABSTRACT FROM AUTHOR]

Model reduction is an approach for fast and cost-efficient modelling of large-scale systems governed by Ordinary Differential Equations (ODEs). Multi-dimensional model reduction has been suggested for reduction of the linear systems simultaneously with respect to frequency and any other parameter of interest. Multi-dimensional model reduction is also used to reduce the weakly nonlinear systems based on Volterra theory. Multiple dimensions degrade the efficiency of reduction by increasing the size of the projection matrix. In this paper a new methodology is proposed to efficiently build the reduced model based on regression analysis. A numerical example confirms the validity of the proposed regression algorithm for model reduction. [ABSTRACT FROM AUTHOR]

Integer goal programming problems arise quite naturally in many real-world applications. In this paper, we propose a reference direction approach and interactive algorithm to solve integer goal programming problem. We use analytic hierarchy process (AHP) to get the reference direction. At each iteration, only one integer linear programming problem is solved to get an efficient solution. Through analytic hierarchy process the decision maker has to provide the preference point such that the original problem has been transformed into linear integer programming model. [ABSTRACT FROM AUTHOR]

Ductile damage mechanics is essential to predict failure during cold metal forming applications. Several damage models can be found in the literature. These damage models are coupled with the mechanical behavior so as to model the progressive softening of the material due to damage growth. However, the identification of damage parameters remains an issue. In this paper, an inverse analysis approach is set-up to identify ductile damage parameters, based on different kind of mechanical tests and observables. The Lemaitre damage model is used and damage is coupled with the material behavior. The Efficient Global Optimization (EGO) method is used in a parallel environment. This global algorithm based on kriging meta-model enables the identification of a set of damage parameters based on experimental observables. Global and local observables are used to identify these parameters and a special attention is paid to the computation of the cost function. Finally, an identification procedure based on displacement field measurements is presented and applied for damage parameters identification. [ABSTRACT FROM AUTHOR]

This paper presents the formulation of an axi-symmetric element based on an efficient method called 'Inverse Approach' (I.A.) for the numerical modeling of cold forging process. In contrast to the classical incremental methods, the Inverse Approach exploits the known shape of the final part and executes the calculation from the final part to the initial billet. The assumptions of the proportional loading and the simplified tool actions make the I.A. calculation very fast. The metal's incompressibility is ensured by the penalty method. The comparison with ABAQUS® and FORGE® shows the efficiency and limitations of the I.A. This simplified method will be a good tool for the preliminary preform design. [ABSTRACT FROM AUTHOR]

Aim of this paper is to develop an adaptive technique for modeling an ammunition trajectory fired from gun to hit a desired aerial target (Surface-to-Air) accurately. The proposed technique for fire control system would follow the estimated trajectory based on ballistic data provided. The essential components of a modern fire control system of a gun required for computational modeling, their connectivity and requirements have also been discussed. The ballistic data of gun ammunition has been exploited in four parameters to get the ballistic solution by modeling. These four parameters are: azimuth angle, elevation angle, initial velocity and miss distance. The target interception depends upon proposed miss-distance concept, hence, the mathematical model computes future position of the target on the basis of present position of target. [ABSTRACT FROM AUTHOR]

Gaussian beam tracing methods have emerged as a standard approach for modeling sound propagation in the ocean. The first implementations were developed in the 1970's by Bucker and evolved significantly. Today there are actually some four different types of Gaussian beam algorithms. They are quite different in terms of both the beam characteristics and their performance. This paper will review the development of the methods and their application to typical ocean acoustic problems. [ABSTRACT FROM AUTHOR]

Methods which provide good conditioning of model identification task in immune inspired, steady-state controller SILO (Stochastic Immune Layer Optimizer) are presented in this paper. These methods are implemented in a model based optimization algorithm. The first method uses a safe model to assure that gains of the process’s model can be estimated. The second method is responsible for elimination of potential linear dependences between columns of observation matrix. Moreover new results from one of SILO implementation in polish power plant are presented. They confirm high efficiency of the presented solution in solving technical problems. [ABSTRACT FROM AUTHOR]

In this paper a computational method and numerical algorithm is developed for finding the optimal control policy for a partially observable system subject to random failure. The condition of the system is modeled by an unobservable continuous-time homogeneous Markov chain. Multivariate data stochastically related to the system state is collected at equidistant sampling times. The system is controlled by a multivariate Bayesian control chart, i.e. full inspection followed by maintenance is performed when the posterior probability that the system is in the warning state exceeds a control limit. A statistical constraint is considered which bounds the probability of a true alarm given by the control chart. The objective is to minimize the long-run expected average cost per unit time by determining the optimal values of the control limit and sampling interval subject to the statistical constraint. The stochastic evolution of the posterior probability process is analyzed and computational algorithm is developed in the semi-Markov decision process framework. Numerical examples are provided which illustrate the effect of the statistical constraint and the performance of the Bayesian control chart is compared with the traditional multivariate χ2 control chart. [ABSTRACT FROM AUTHOR]

A simple algorithm finds the partition of a data interval optimizing the fitness of a model that represents the underlying signal as constant over the elements of the partition. Using dynamic programming the exponentially large space of partitions of N data points is implicitly but exhaustively searched in time O(N2). This paper also describes an extension to optimal partitions of higher dimensional data spaces, with application to multivariate signal processing, image processing, cluster analysis, density estimation in 3-dimensional redshift surveys, etc. The algorithm finds the exact global optimum, automatically determines the model order (the number of segments), and has a convenient real-time mode. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

To better predict the polycrystalline behavior at large deformations, a robust time integration algorithm at the single crystal level is of vital importance. The present paper analyzes often-used integration approaches for rate-dependent single crystal plasticity in the area and classifies them into three representative approaches. Three different formulations are grouped into the first approach, which is based up the deformation gradient. The second approach is defined in terms of the slip rates. A modification is proposed to alleviate the numerical stabilities to the second approach upon analyzing the Jacobian. Comparisons between these two approaches show that they demonstrate very similar phenomenology in terms of kinematics and kinetics. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this paper, we present results from an experimental evaluation of centroiding algorithms, simple center of gravity (CoG) and weighted center of gravity (WCoG) in a Shack Hartmann wavefront sensor at different light levels and background noise conditions. CoG performs better than WCoG at good light conditions. WCoG performs better than CoG algorithm at low light level conditions and in cases of high intensity. [ABSTRACT FROM AUTHOR]

The inverse problem associated with reconstruction of Poisson blurred images has attracted attention in recent years. In this paper, we propose an alternative unified approach to blind image deconvolution problem using fuzzy median filter as Gibbs prior to model the nature of inter pixel interaction for better edge preserving reconstruction. The performance of the algorithm at various SNR levels has been studied quantitatively using PSNR, RMSE and universal quality index (UQI). Comparative analysis with existing methods has also been carried out. [ABSTRACT FROM AUTHOR]