The paper preseiits an investigation on vibrations of mechanical systems arising from unbalanced masses. At the experimental stage, a power transmission shaft is driven at different operating speeds, therefore, the paranieters, such as displacement, velocity and acceleration in vertical direction due to body vibrations are measured at various points on the frame before and after balancing. Balancing has provided a definite decrease in the amplitudes of vibration parameters.
In addition to these studies mentioned above, the use of Neural Network (NN) for vibration analysis of a frame due to unbalanced transmission shaft is also achieved. The results show that the NN approach exactly follows the foregoing results. This implies the necessity of the non-linear modelling capabilities of the NN for vibration problems of mechanical systems.
This paper presents an adroit utilization of dimensional analysis-based model theory by which the deformation of a structure - however complex - can be elegantly and easily obtained. The structure is loaded by a concentrated lateral load of arbitrary location and magnitude. The relevant technique is outlined in some details; therefore the reader is advised to follow the presented routine closely. By doing so, he will be impressed by the prowees and economy of the described process. In the Preamble, the more important relevant theorems and relations - without proofs - are given in greatly condensed forms. This summary will help the reader to understand the subsequent application presented. Full treatment of the theories and practice of applied dimensional model theory can be found in [1], which the interested and motivated reader is advised to consult. and Obsahuje seznam literatury
Estimation of shift between signals of two ultrasound images is the key of sonoelastography. Comparison of three methods - cross-correlation function and two versions of SAD (sum of absolute differences) has been conducted for various displacements and estimation parameters using a soft tissuemimicking gelatin phantom with harder inclusion. Resulting displacement maps were evaluated by comparison of average values and their standard deviations. and Obsahuje seznam literatury
The impact of the arrival of the exotic coccinellid Harmonia axyridis on the biological control and dispersion of apple mites and aphids, and on the vertical distribution of the established coccinellids Coccinella septempunctata and Coleomegilla maculata have been studied. Assemblages of adults of the three coccinellid species were tested on apple saplings and on apple trees against Aphis citricola and Tetranychus urticae. The presence or substitution of adults of H. axyridis for adults of C. maculata or C. septempunctata did not reduce the predation impact on mite or aphid prey. H. axyridis was a more efficient predator of mites than was C. septempunctata and generated lower prey dispersal from host plants. Substitutions of adults of H. axyridis for those of C. maculata, and in some cases of C. septempunctata, resulted in greater reduction in number of aphids. On apple trees, the three coccinellid species occurred at different heights. Neither C. maculata nor C. septempunctata modified their vertical distribution on apple tree over a 24 hour period in response to the presence of H. axyridis.
Recenzentka vítá české vydání knihy Andrease Kosserta Kalte Heimat: Die Geschichte der deutschen Vertriebenen nach 1945 (München 2008), předkládající relativně nový a ucelený pohled na osud poválečných německých vyhnanců ze střední a východní Evropy v obou částech rozděleného Německa, který je ve zdejším prostředí vnímán často zkresleně a na základě nedostatečných informací. Autor se však podle ní bohužel nevyhnul jistému zjednodušování, nepřesnostem a tendenčnosti, ve kterých se projevuje jednak jeho neznalost českých a polských pramenů a literatury, jednak osobní zainteresovanost na tématu. Odbourává sice navenek deklarovaný mýtus o úspěšné integraci vyhnanců ve Spolkové republice Německo, sám však vytváří schematický obraz „dobrých vyhnanců“ a ostatních „zlých Němců“., In her review of the Czech translation of Andreas Kossert’s Kalte Heimat: Die Geschichte der deutschen Vertriebenen nach 1945 (Munich, 2008), the reviewer welcomes the Czech edition, which presents a comparatively new and comprehensive view of the fate of the ethnic Germans who were expelled from central and eastern Europe after the Second World War and settled in both parts of divided Germany. In the Czech Republic, the perception of their fate is too often distorted, presented without sufficient information. According to the reviewer, however, the author has not avoided oversimplification, imprecision, and tendentiousness, manifesting on the one hand a lack of knowledge of Czech and Polish primary sources and secondary literature and, on the other, his personal involvement in the topic. Although he dispels the generally declared myth about the expellees’ successful integration into the Federal Republic of Germany, he paints an oversimplified picture of the ‘good expellees’ on the one hand and the ‘wicked Germans’ on the other., and [autor recenze] Sandra Kreisslová.