Deposits in municipal waste incinerators are very inhomogeneous in structure and constitution. They cause corrosion and reduce the efficiency, so they need to be removed frequently. Among other systems, operators use water cannons for the deposit removal. Two different removal mechanisms of water-cannon cleaning are suggested: A direct shattering of the deposit by the impact of the water jet, as well as the cracking caused by thermal stresses where droplets cool the deposits. As the contribution of each of the aforementioned mechanisms to the overall cleaning efficiency is unknown, we performed empirical investigations to determine the dominating effect. In a first experimental setup focusing on thermal stress, cold droplets were applied onto hot deposits taken from a waste incinerator. Results showed that the cleaning effect strongly depends on the deposit thickness and structure, so that the deposits could be categorised in three different groups. A second measurement campaign focused on the influence of deposit material, deposit temperature and water jet momentum. It could be shown that both deposit material and temperature have a significant effect on the cleaning efficiency, whereas an increase in water jet momentum only led to modest improvements. The combination of these two parameter studies implies that the influence of the thermal stress outweighs that of the momentum. This knowledge is applicable to the cleaning setup by increasing the temperature gradient.

A planing catamaran is a high-powered, twin-hull water craft that develops the lift which supports its weight, primarily through hydrodynamic water pressure. Presently, there is increasing demand to further develop the catamaran's planing and seakeeping characteristics so that it is more effectively applied in today's modern military and pleasure craft, and offshore industry supply vessels. Over the course of the past ten years, Vorus (1994,1996,1998,2000) has systematically conducted a series of research works on planing craft hydrodynamics. Based on Vorus' planing monohull theory, he has developed and implemented a first order nonlinear model for planing catamarans, embodied in the computer code CatSea. This model is currently applied in planing catamaran design. However, due to the greater complexity of the catamaran flow physics relative to the monohull, Vorus's (first order) catamaran model implemented some important approximations and simplifications which were not considered necessary in the monohull work. The research of this thesis is for relieving the initially implemented approximations in Vorus's first order planing catamaran theory, and further developing and extending the theory and application beyond that currently in use in CatSea. This has been achieved through a detailed theoretical analysis, algorithm development, and careful coding. The research result is a new, complete second order nonlinear hydrodynamic theory for planing catamarans. A detailed numerical comparison of the Vorus's first order nonlinear theory and the second order nonlinear theory developed here is carried out. The second order nonlinear theory and algorithms have been incorporated into a new catamaran design code (NewCat). A detailed mathematical formulation of the base first order CatSea theory, followed by the extended second order theory, is completely documented in this thesis.

The main content of of this thesis is a construction design and analysis of a machine for cutting tires. The resulting solution emerges from the design options and the option that meets the best selection criteria is chosen. Then the thesis stops for a while at the choice of cutting technology and tries to exemine its suitability for cutting tires. In its other part there is an attempt to clarify the relevant parts of the machine, where the benefits of three-dimensional views is used. Basic design and check calculations are done in the selected machine parts.

This study deals with technology of abrasive water jet material cutting and influence of cutting head feed rate on surface topography of cut walls with regards to roughness. Eight parameters were chosen based on the CSN EN ISO 4288 standard representing quality of surface after AWJ cutting. When AWJ cutting the chosen material – commercially pure ASTM B265 grade 2 titanium – feed rate was being changed and in order to obtain information about each parameter´s distribution in various depths of the cut, surface composition was evaluated. It was found out that feed rate has significant influence on surface and that the profile elements´ width grows when increasing the feed rate and cut depth. Furthermore, two selected feed rate results were compared to laser beam technology and conclusion for the selected material was made that AWJ cutting is more preferable due to final roughness and no heat affect on the material.

This master’s thesis has been elaborated as a part of master’s studies of engineering technology M2I-K, major in M-STM – Engineering technology and industrial management and deals with the problem of a transition to a self-production of previously purchased distance washers. Distance washers were purchased in six different types of similar shape, each type in four different thicknesses. One of these types was chosen as a representative for this master’s thesis. We shall explore the possibilities of self-production with the emphasis on economical validation of the transition. The distance washer is a flat part, the intermediate being sheet metal. Technologies considered for manufacturing the washers correspond to the technical facilities and equipment available at the production hall of the company this project is planned for. The company possesses technology for CO2 laser cutting, cutting by CNC punching machine and cutting in the punching tool. To provide a complex overview we shall also enquire into cooperated technologies such as water jet and plasma cutting, oxy-acetyleny cutting and CNC working. All options are evaluated with regard to the production expenses and lead to a most economically plausible method of manufacturing or, if need be, give reasons for going back to purchasing the part from the current supplier.