The paper deals with the calibration methods for machines with parallel kinematics. The procedures are based on Newton method for numerical solution of overconstrained system of nonlinear equations. The methods are applied on redundantly actuated machine with planar kinematics named ‘Sliding Star‘. The redundant measurements of relative motions in joints allow on-line calibration in real time of machine tool operation. This could significantly improve the thermal inaccuracy of machine tools with parallel mechanisms. and Obsahuje seznam literatury
The paper deals with a problem of modeling discrete variables depending on continuous variables. This problem is known as the logistic regression estimated by numerical methods. The paper approaches the problem via the recursive Bayesian estimation of mixture models with the purpose of exploring a possibility of constructing the continuous data dependent switching model that should be estimated on-line. Here the model of the discrete variable dependent on continuous data is represented as the model of the mixture pointer dependent on data from mixture components via their parameters, which switch according to the activity of the components. On-line estimation of the data dependent pointer model has a great potential for tasks of clustering and classification. The specific subproblems include (i) the model parameter estimation both of the pointer and of the components obtained during the learning phase, and (ii) prediction of the pointer value during the testing phase. These two phases can be joined together in the case of necessity. A real-data experimental comparison with theoretical counterparts shows a competitiveness of the approach in the discussed field.
Motion planning of mobile robots is a complex problem. The complexity further increases when it comes to path planning in dynamic environments. This paper presents an algorithm for on-line path planning of mobile robots in unknown environments with moving obstacles. A mathematical model is established which considers all the current on-line information of robot as well as nearing obstacles. Particle Swarm Optimization technique is used to optimize the velocity parameters of the robot, to arrive at the shortest collision-free trajectory, satisfying dynamic constraints. Simulation results show that the proposed algorithm is computationally efficient and effective.
Previous studies on on-off intermittency in continuum systems are generally based on the synchronization of identical chaotic oscillators or in nonlinear systems driven by the Duffing oscillator. In this paper, one-state on-off intermittency and two-state on-off intermittency are observed in two five-dimensional continuum systems, respectively, where each system has a two-dimensional subsystem driven by the chaotic Chen system. The phenomenon of intermingled basins is observed below the blowout bifurcation. Basic statistical properties of the intermittency are investigated. It is shown that the distribution of the laminar phase follows a -3/2 power law, and that of the burst amplitudes follows a -1 power law, consistent with the basic statistical characteristics of on-off intermittency.
Oncocytic Schneiderian papilloma (OSP) is one of the three morphologically distinct tumors that arise from Schneiderian membrane (the others include exophytic papilloma and inverted papilloma). OSP almost always occurs unilaterally in the paranasal sinuses, usually in the maxillary sinus, ethmoid cells or sphenoid sinus. We report a case of a 64-year-old woman with OSP arising from the left frontal sinus. In the report herein, we describe an OSP originating in the region of frontal sinus, which, to the best of our knowledge, represents the first documented example in English literature of OSP developing in this anatomical site. and D. Kalfert, J. Laco, P. Celakovský, K. Smatanová, M. Ludvíková