No description available.

Creation of vacuum is very slow, energetically and technologicaly demanding process. Closing of valve is very simple and fast process which produces pressure surges when moving cylinder of fluid is stopped. The goal of this thesis is to find out, if it is possible to combine these processes. To reach this goal, 1D model of compressible gas flow and pressure surges in direct pipeline was made. Then follows experimental measurement evaluation and assessment of potential that the technology offers.

The thesis deals with the classification of the retinal blood vessels in retinal image data. The first part of the thesis deals with the anatomy of the human eye and focuses on the description of the retina and its blood circulation. It further describes the principle of fundus camera and experimental video ophthalmoscope. The second part of the thesis is devoted to a literature search of academic publications that deal with the classification of the retinal vessels into arteries and veins. Subsequently, the principle of selected machine learning methods is presented. Based on the literature research, two methods for the classification of the blood vessels were proposed, the first one using the SVM classifier and the second one using the convolutional neural network U-Net. At the end, the analysis of vascular pulsations was performed. The practical part of the thesis was carried out in Matlab programming interface and images from the RITE, IOSTAR and AFIO database were used for classification and the retinal video sequences taken with an experimental video ophthalmoscope were processed in the analysis of pulsations.

This dissertation work describes design and construction of simulated aorta device intended to demonstrate performance of the intra-aortal balloon catheter (IAB), and to test reaction of the contra-pulsation pump during simulated cardiac output in conditions of tachycardia, bradycardia and arrhythmia. The major part of the device is transparent plastic tube. The pressure pulses (waves) are generated inside this plastic tube to simulate real cardiac output. These pressure pulses are generated by step motor with membrane. The step motor is controlled by programmable control system AMiNi-E. Individual pressure pulses simulate cardiac output in conditions of tachycardia, bradycardia and arrhythmia. Required simulated cardiac output is selected by control switches. Generated pressure pulses are read by pressure sensor and are transferred to the control system of the configuration computer. Read data can be displayed as graphs in program Microsoft Excel. The intra-aortal balloon catheter (IAB) is inserted inside the aorta and is connected with contra-pulsation pump which on pressure pulse is responding.

The main goal of this thesis is a determination of an idle stray losses in induction machine and creation calculation program in MATLAB. The stray losses are caused especially by the eddy currents on the surface of stator and rotor, further by a pulsation of these currents owing to the periodical change of air-gap permeance, magnetic induction in stator and rotor teeth and a differential leakage. Value of stray losses are different of engine construction especially by it are scoring insulated, uninsulated, straight or slant.

Main issue of this master´s thesis deals with high-frequency pulsations caused by cavitating hydraulic components (in this case nozzle and throttle valve). In first measurement on the nozzle was not a high-frequency sensor set in the way, so the evaluation was incorrect. After re-setting of the way was the nozzle measured again and the pulsations were evaluated correct this time. During the last measurement was the sensor located behind the throttle valve, which was with gradual opening and cavitation treatment measured. Resulting dependencies worked out on time dependence. A special mathematical method, Fourier transformation, was used. It transformed pressure amplitudes into frequency dependence. Evaluation of dependecies is the basic step for frequency band assesment, in which the cavitation on particular components happens.

The thesis includes two main parts. The first part comprises the theoretical analysis, i.e. literary research. It has been focused on questions regarding compressive pulsation and possible damping elements. The second part focuses on the formation of mathematical model of transition of matrix gas accumulator, the hydraulic set formation by the transition matrix method, the deduction of innate and constrained values and the compressible liquid mode shapes in cylindrical space.

This thesis deals with turbulent flows in 90 degree curved pipes of circular cross-section. The flow cases investigated experimentally are turbulent flow with and without an additional motion, swirling or pulsating, superposed on the primary flow. The aim is to investigate these complex flows in detail both in terms of statistical quantities as well as vortical structures that are apparent when curvature is present. Such a flow field can contain strong secondary flow in a plane normal to the main flow direction as well as reverse flow. The motivation of the study has mainly been the presence of highly pulsating turbulent flow through complex geometries, including sharp bends, in the gas exchange system of Internal Combustion Engines (ICE). On the other hand, the industrial relevance and importance of the other type of flows were not underestimated. The geometry used was curved pipes of different curvature ratios, mounted at the exit of straight pipe sections which constituted the inflow conditions. Two experimental set ups have been used. In the first one, fully developed turbulent flow with a well defined inflow condition was fed into the pipe bend. A swirling motion could be applied in order to study the interaction between the swirl and the secondary flow induced by the bend itself. In the second set up a highly pulsating flow (up to 40 Hz) was achieved by rotating a valve located at a short distance upstream from the measurement site. In this case engine-like conditions were examined, where the turbulent flow into the bend is non-developed and the pipe bend is sharp. In addition to flow measurements, the effect of non-ideal flow conditions on the performance of a turbocharger was investigated. Three different experimental techniques were employed to study the flow field. Time-resolved stereoscopic particle image velocimetry was used in order to visualize but also quantify the secondary motions at different downstream stations from the pipe bend while combined hot-/cold-wire anemometry was used for statistical analysis. Laser Doppler velocimetry was mainly employed for validation of the aforementioned experimental methods. The three-dimensional flow field depicting varying vortical patterns has been captured under turbulent steady, swirling and pulsating flow conditions, for parameter values for which experimental evidence has been missing in literature. / QC 20120425

No description available.

No description available.