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Start Over Coverage 225-235

2. Development of the basic dynamical model of a squirrel cage motor

Creator:
Hajžman, Michal, Byrtus, Miroslav, and Zeman, Vladimír
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
squirrel cage motor, rotor dynamics, finite element method, modal analysis, and parameter tuning
Language:
English
Description:
This paper deals with the basic dynamical model of electromotor whose creation motivated by problems of electromotor vibrations and its subsequent fatigue. The model is chaacrterized by a flexible shaft with mounted padket of sheet metals that are equipped with parallel copper bars connected by end shortcircuit rings. Finite element analysis is used for the disretization of the shaft, while the sheet metal packet of cylindrical shape is modelled as a set of rigid bodies joined using chosen viscoelastic forces and torques. The shortcircuit rings are supposed to be rigid in this basic dynamical model and the pieces of copper bars are substituted by massless springs of calculated properties. Problematic model parameters are identified by means of performed experimental modal analysis. and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Endoparasitic mites of the genus Endotrombicula Ewing, 1931 (Acari: Prostigmata: Parasitengona: Trombiculidae) from African and Madagascan anurans, with description of a new species

Creator:
Wohltmann, Andreas, Preez, Louis du, Rödel, Mark-Oliver, Köhler, Jörn, and Vences, Miguel
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Amphibia, Anura, Mantellidae, Ptychadenidae, endoparasites, Endotrombicula ptychadenae, new species, Africa, and Madagascar
Language:
English
Description:
A sample of over 6,000 specimens of frogs belonging to about 120 species of all families occurring in West Africa and Madagascar were screened for parasitic mites. Three species of Endotrombicula Ewing, 1931 were found in representatives of two African and two Madagascan frog families. All Trombiculidae found in African frogs belonged to Endotrombicula pillersi (Sambon, 1928), whereas in Madagascar E. madagascariensis (Sambon, 1928) and E. ptychadenae sp. n. were sampled. These three species are described, data about their parasitic associations are provided, and their zoogeographical distribution is discussed. Only those frog species that spend a considerable time in terrestrial ground habitats were parasitized; neither arboreal nor strictly aquatic frogs were infected. The geographic distribution of Endotrombicula, restricted to Africa, the Arabian Peninsula and Madagascar, suggests that these mites invaded Madagascar from the African continent. This is supported by the observation that the ancestors of Ptychadena mascareniensis (Duméril et Bibron) (Ptychadenidae), the host of E. ptychadenae, colonized Madagascar from the African continent quite recently, possibly accompanied by its Endotrombicula parasites.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Extremal metrics and modulus

Creator:
Anić, I., Mateljević, M., and Šarić, Dragomir
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
extremal distance, conformal capacity, and Beurling theorem
Language:
English
Description:
We give a new proof of Beurling’s result related to the equality of the extremal length and the Dirichlet integral of solution of a mixed Dirichlet-Neuman problem. Our approach is influenced by Gehring’s work in $\mathbb{R}^3$ space. Also, some generalizations of Gehring’s result are presented.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

5. Sensitivity analysis of a blade couple under rotation

Creator:
Byrtus, Miroslav, Hajžman, Michal, and Zeman, Vladimír
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
sensitivity analysis, friction damper, blades, bladed disk, and harmonic balance method
Language:
English
Description:
The aim of the paper is to show the influence of design parameters on the suppression of rotating blade vibration. The derivation of nonlinear mathematical model of a blade couple mutually connected by a friction element is summarized. After that, the linearization of the mathematical model is performed by harmonic balance method. The linearized model is used for sensitivity analysis of real and imaginary parts of eigenvalues in the course of rotation and sensitivity analysis of stead-state response with respect to the design parameters of internal friction coupling. and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public