This paper deals with the global position control problem of robot manipulators in joint space, a new family of control schemes consisting of a suitable combination of hyperbolic functions is presented. The proposed control family includes a large class of bounded hyperbolic-type control schemes to drive both position error and derivative action terms plus gravity compensation. To ensure global asymptotic stability of closed-loop system equilibrium point, we propose an energy-shaping based strict Lyapunov function. To verify the efficiency of the proposed control algorithm, an experimental comparative analysis between the well known unbounded linear PD control and three hyperbolic-type control schemes of the proposed family on a three degrees of freedom direct-drive robot manipulator is analysed.
We investigate the category $\text{mod}\Lambda $ of finite length modules over the ring $\Lambda =A\otimes _k\Sigma $, where $\Sigma $ is a V-ring, i.e. a ring for which every simple module is injective, $k$ a subfield of its centre and $A$ an elementary $k$-algebra. Each simple module $E_j$ gives rise to a quasiprogenerator $P_j=A\otimes E_j$. By a result of K. Fuller, $P_j$ induces a category equivalence from which we deduce that $\text{mod}\Lambda \simeq \coprod _jbad hbox P_j$. As a consequence we can (1) construct for each elementary $k$-algebra $A$ over a finite field $k$ a nonartinian noetherian ring $\Lambda $ such that $\text{mod}A\simeq \text{mod}\Lambda $, (2) find twisted versions $\Lambda $ of algebras of wild representation type such that $\Lambda $ itself is of finite or tame representation type (in mod), (3) describe for certain rings $\Lambda $ the minimal almost split morphisms in $\text{mod} \Lambda $ and observe that almost all of these maps are not almost split in $\text{Mod}\Lambda $.
In this paper, we demonstrate the computational consequences of making a simple assumption on production cost structures in capacitated lot-size problems. Our results indicate that our cost assumption of increased productivity over time has dramatic effects on the problem sizes which are solvable. Our experiments indicate that problems with more than 1000 products in more than 1000 time periods may be solved within reasonable time. The Lagrangian decomposition algorithm we use does of course not guarantee optimality, but our results indicate surprisingly narrow gaps for such large-scale cases - in most cases significantly outperforming CPLEX. We also demonstrate that general CLSP's can benefit greatly from applying our proposed heuristic.
The paper presents a simple method to check a positiveness of symmetric multivariate polynomials on the unit multi-circle. The method is based on the sampling polynomials using the fast Fourier transform. The algorithm is described and its possible applications are proposed. One of the aims of the paper is to show that presented algorithm is significantly faster than commonly used method based on the semi-definite programming expression.
The absolute gravity measurements are an important tool for reliable monitoring geodynamic phenomena. Based on the experience with the absolute gravimeter FG5#215 (gravimeter of the Center for Earth Dynamics Research), the accuracy of FG5 absolute gravimeters is presented in this study. The instrumental reproducibility of this meter is characterized by the value of 0.7 μGal. Discussed are important environmental effects on gravity measurements, such as atmospheric and hydrological effects, understanding of which is necessary for correct and reliable interpretation of the repeated absolute gravity measurements in geodynamics., Vojtech Pálinkáš, Jakub Kostelecký and Jaroslav Šimek., and Obsahuje bibliografii
The perturbed Laplacian matrix of a graph G is defined as DL = D−A, where D is any diagonal matrix and A is a weighted adjacency matrix of G. We develop a Fiedler-like theory for this matrix, leading to results that are of the same type as those obtained with the algebraic connectivity of a graph. We show a monotonicity theorem for the harmonic eigenfunction corresponding to the second smallest eigenvalue of the perturbed Laplacian matrix over the points of articulation of a graph. Furthermore, we use the notion of Perron component for the perturbed Laplacian matrix of a graph and show how its second smallest eigenvalue can be characterized using this definition., Israel Rocha, Vilmar Trevisan., and Obsahuje seznam literatury
Matrix polynomials play an important role in the theory of matrix differential equations. We develop a fixed point method to compute solutions of matrix polynomials equations, where the matricial elements of the matrix polynomial are considered separately as complex polynomials. Numerical examples illustrate the method presented.
For a $C^1$-function $f$ on the unit ball $\mathbb B \subset \mathbb C ^n$ we define the Bloch norm by $\|f\|_\mathfrak B=\sup \|\tilde df\|,$ where $\tilde df$ is the invariant derivative of $f,$ and then show that $$ \|f\|_\mathfrak B= \sup _{z,w\in {\mathbb B} \atop z\neq w} (1-|z|^2)^{1/2}(1-|w|^2)^{1/2}\frac {|f(z)-f(w)|}{|w-P_wz-s_wQ_wz|}.$$.
† Pyrenicocephalus jarzembowskii, gen. et sp. n. (Hemiptera: Heteroptera: Enicocephalomorpha: Enicocephalidae: Enicocephalinae) from Early Eocene, London Clay, England, Isle of Sheppey, is described and illustrated according to the unique pyritized adult head reported as a larval enicocephalid head by Jarzembowski (1986). The head anatomy of similar and related genera of Enicocephalinae is compared and the close relationship of the new genus to a clade including the extant genera Oncylocotis, Embolorrhinus and Hoplitocoris is suggested, most probably as the sister genus to Hoplitocoris (presently with Afrotropical, East Palaearctic and Oriental range).