Research study of „Tilt pad bearings“ (computational and experimental modelling)

Bakalářská práce je zaměřena na výpočtové a experimentální modelování naklápěcích segmentových ložisek. Výpočtové i experimentální modelování vychází z řešení problematiky mazání anglickým profesorem Osbornem Reynoldsem, publikované roku 1886. Hlavní částí práce tvoří popis v současnosti nejpoužívanějších výpočtových modelů, v čele s TEHD analýzou, a dále jediných dvou experimentálních zařízení pro testování naklápěcí segmentová ložiska. Práce je doplněna o predikce vývoje výpočtových modelů u naklápěcích segmento-vých ložisek.The bachelor’s thesis is focused on the computational and experimental modelling of the tilting pad bearings. The computational and experimental modelling is based on solving the lubrication theory provided by English professor Osborn Reynolds, published in 1886. The main part of the thesis is the description of the most widely used computational models, especially TEHD analysis, and the description of the only two experimental devices for the testing of the tilting pad bearings. The thesis is supplemented with the prediction of the development of the computational modelling in the near future.

Energetical utilization of waste, especially sewage sludge

Tato bakalářská práce pojednává o energetickém využití kalu. Proces je popsán od úpravy kalu až po čištění spalin. Hlavní důraz je kladen na spalování, které se řídí legislativou. Nejdříve jsou uvedeny technologie úprav a nakládání s kalem, kam spadá i termické zpracování, ve kterém je důkladněji popsán proces spalování. Dále jsou uvedeny metody pro spoluspalování kalu a zařízení pro přímé spalování. Práce je zakončena kapitolou čištění spalin.This bachelor´s work discusses about energetical utilization of sewage sludge. The process is described from sludge treatment to flue gas cleaning. The main emphasis is on incineration, which are governed by legislation. First are listed sludge treatment and utilization technology which included thermal processing in which is thoroughly described the process of incineration. The following are methods for co-incineration of sludge and devices for direct incineration. Work is finished by chapter about flue gas cleaning.

SIZE EFFECT ON THE ULTIMATE DRYING SHRINKAGE OF CONCRETE - EXPERIMENTAL EVIDENCE AND ENGINEERING PRACTICE

The design and behavior of creep-sensitive structures can be to a large extent dependent on the evolution of drying shrinkage. Drying shrinkage of concrete measured on standard laboratory specimens is very time demanding, furthermore, the extrapolation based on the short-term measurements is an ill-posed problem and can lead to large errors. Additionally, the final magnitude of shrinkage is size-dependent which makes the transition from the laboratory data to real structure even more challenging. The present paper evaluates this size effect based on the data gathered in the Creep and shrinkage database developed at the Northwestern university and the data from the literature. Finally, this size effect is compared against the current codes of practice and recommendations

MODELING TIME-DEPENDENT DEFORMATIONS OF CONCRETE MEMBERS SUBJECTED TO SYMMETRIC AND ASYMMETRIC DRYING

The time-dependent behavior of concrete members with uniform cross-section subjected to symmetric drying can be predicted with one of many models anchored in the design codes. Since these models use the cross-sectional approach, only the average quantities can be obtained. More complex phenomena can be investigated by means of a coupled hygro-mechanical finite element analysis. Owing to insufficient or missing experimental data, the input parameters for the moisture transport model are often tuned to match the development of axial shrinkage or moisture loss measured on small-scale laboratory specimens. In this paper it is assessed whether this approach leads to a unique set of parameters of the Bažant-Najjar model for moisture diffusion. Additionally, for the selected sets of parameters the analysis is repeated with modified size and/or boundary conditions leading to asymmetric drying and the results are discussed

Benchmark VERCORS 2022: blind prediction of time-dependent behavior of concrete containment building with low and high-fidelity models

The VERCORS program aims to acquire an extensive experimental dataset collected to provide a solid basis for numerical modeling of concrete containment buildings (CCBs). In order to cover the entire life-span of a real containment, the measurements are done on 3× smaller mock-up which leads to 9-fold acceleration of all processes related to drying. The goal for the participants of the third VERCORS benchmark was to predict the behaviour of the CCB based on standard laboratory measurements on VERCORS concrete. The previous paper [1] presented the calibration procedure of material models for moisture transport and time-dependent behavior of concrete and summarized the results obtained with a computationally efficient low-fidelity model (LFM). The present paper compares the responses of the LFM and a high-fidelity model (HFM) with a detailed geometry of the entire containment and presents a comparison with the experimental data collected over the last 8 years on the VERCORS mockup

Modeling of Concrete Creep Based on Microprestress-solidification Theory

Creep of concrete is strongly affected by the evolution of pore humidity and temperature, which in turn depend on the environmental conditions and on the size and shape of the concrete member. Current codes of practice take that into account only approximately, in a very simplified way. A more realistic description can be achieved by advanced models, such as model B3 and its improved version that uses the concept of microprestress. The value of microprestress is influenced by the evolution of pore humidity and temperature. In this paper, values of parameters used by the microprestress-solidification theory (MPS) are recommended and their influence on the creep compliance function is evaluated and checked against experimental data from the literature. Certain deficiencies of MPS are pointed out, anda modified version of MPS is proposed

Benchmark VERCORS 2022: mechanical response of the prestressed concrete containment wall to ambient conditions

The VERCORS benchmark was developed to provide a solid experimental basis for numerical modeling of concrete containment buildings (CCBs) to extend their lifespan. The goal of the first phase of the third benchmark is to present a blind prediction of CCB’s behavior across the whole lifespan and under periodic pressure tests. This paper summarizes the calibration of the material model based on the Microprestress-solidification (MPS) theory according to the provided laboratory experimental data. A special emphasis is given to the influence of the ambient conditions on drying creep and transient thermal creep of concrete and the calibration of the corresponding material parameters. These phenomena are studied on a representative section of the containment wall using weakly coupled thermo-hygro-mechanical analyses

COMPARISON OF DRYING SHRINKAGE AND DRYING CREEP KINETICS IN CONCRETE

The aim of this paper is to show and compare the time evolution of drying shrinkage and drying creep in concrete from three different perspectives. The first one analyzes the basic equations defined in the most common design codes and prediction models for the description of the long-term behavior of concrete (ACI 209, EC2, Model Code 2010, B3, B4). Next, the evolution of drying creep and shrinkage is examined by processing suitable experimental data available from the database developed at the Northwestern University. Finally, the last point of view investigates the results obtained from the finite element simulations employing the material point approach, in particular, the material model based on the Microprestress-Solidification theory

Behavior of predried mature concrete beams subject to partial wetting and drying cycles

The presented research focuses on the behavior of predried concrete beams with 2.5 m span subjected to cycles of nonsymmetric wetting and drying. Wetting is induced by partially immersing the specimens in a water basin. The submerged portion of the specimens was relatively low (1/5 to 1/10 of their height) leading to a highly nonuniform and nonsymmetric distribution of eigenstrains due to concrete swelling. Unlike conventional experiments on the volume changes of concrete, the measured quantity is not the axial deformation but the vertical displacement instead. This paper presents the experimental data obtained within two wetting and drying cycles, running over 1 year

Business Plan

Bakalářská práce se zabývá vypracováním podnikatelského plánu na založení nového restauračního zařízení ve vybrané lokalitě, konkrétně město Rosice. V teoretické části jsou definovány pojmy “podnikání“ a “podnikatelský plán“. Analytická část se zaměřuje na identifikaci stávající konkurence a potencionálních zákazníků. Část praktická se zaměřuje na předpokládané náklady a výnosy. Účelem práce je vytvoření návodu, jak založit co nejefektivněji podnik a začít podnikat.This bachelor thesis deals with developing a business plan to establish a new restaurant facility in the chosen location, specifically the city Rosice. In the theoretical part, the terms "business" and "business plan" are defined. The analytical part focuses on the identification of existing competition and potential customers. The practical part is focused on the anticipated costs and revenues. The main object of this thesis is a guide how to start a business as efficiently as possible and start a business.