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Separation of rigid particles from heterogeneous suspension
Prax, Ondřej ; Debreczeni, Ondřej (referee) ; Pochylý, František (advisor)
The bachelor thesis contains a literature search dealing with the separation of solid particles from a heterogenic suspension. The first part is aimed at separation methods. Then, a chapter follows dealing with separation devices, which are used in waste water treatment plants. A more detailed description of the separator used for the separation of sand from waste waters is part of this paper. The described device serving to separate solid particles from a suspension uses the combination of sedimentation and separation methods. To visualize the separator a 3D model in Autodesk Inventor Professional 9 device was used in the presented paper.
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Optimizing of Polymer Surface Treatment for Microscopic Examination
Horská, Pavlína ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Supramolecular structure of eight commercial types of iPP, its blends with poly(L-lactide) (PP-PLLA) and copolymers with ethylene-propylene rubber (PP-EPR) together with four types of polyethylene (LDPE, HDPE) was uncovered and observed in this work. The spherulitic structure of iPP and PE homopolymers and PP copolymers was uncovered by etching of six different solutions of mineral acids with KMnO4 and by dissolution in four selected solvents. The latter was found to be ineffective. The structure of PP-PLLA blends was uncovered only after recrystallization (the change of structure by annealing and cooling rate). The uncovered crystalline structure was observed directly by confocal laser scanning microscope (CLSM) and SEM. Crystallinity together with a size distribution of crystallites was determined by DSC. It was proved that spherulitic supramolecular structure was easy to uncover by chemical etching only for molded samples and for fracture surfaces of injected samples. The efficiency of etchants varied but, generally, the samples with high degree of crystallinity were etched earlier. The etchants containing nitric acid and high content of sulphuric acid uncovered fine details of shperulites with respect to mixtures containing orthophosporic acid. It was also observed that not only the etchant (especially with nitric acid) itself but also its vapors were effective. The structure was revealed later but the appearance was plastic (3D) and the structure was very fine. The supramolecular structure of PP-PLLA blends differed with amount of each component. The ethylene-rubber phase came forth with increasing time of etching while PP spherulites disappeared in PP-EPR samples. CLSM was shown to be very good tool for observing supramolecular structure of studied samples with respect to SEM, which was proved to be entirely unsuitable for polyolefines. DSC is recommended to be performe before uncovering supramolecular structure for basic information about proportion of amorphous/crystalline phase and size of crystallites.
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Interaction between surfactants and hyaluronan with different molecular weight.
Vašíčková, Kamila ; Lehocký,, Marián (referee) ; Pekař, Miloslav (advisor)
The behavior of the system consisted by mixture of two different molecular weight hyaluronates and surfactant was investigated. Mixtures were 17 kDa hyaluronate with 1,46 MDa, 73 kDa with 1,46 MDa, 300 kDa with 1,46 MDa, 806 kDa with 1,46 MDa and 1800 kDa with 1,46 MDa. These compounds were always mixed in the weight ratios 70:30, 50:50 and 30:70. As the surfactant cetrimonium bromide and TWEEN 20 were used. Interactions were studied in aqueous solution with different ionic strength. Sudan red was used as hydrophobic dye. In all experimental series with cetrimonium bromide was observed phenomenon of discontinuous separated phases, described as pearls. Samples containing pearls were tested on stability, were dried and rehydrated back, as were also heated in solution. Subsequently, the particle size was measured in the remaining sample after pearls were filtrated. Mixtures of hyaluronate were characterized by measuring the viscosity using rheology microrheology. It was found that these compounds are heterogeneous and each sample point is not the same viscosity.
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The current effectivness of bankruptcy prediction models in the conditions of Central and Eastern Europe
Honzíček, Štěpán ; Kuběnka,, Michal (referee) ; Karas, Michal (advisor)
Bachelor’s thesis describes issues of bankruptcy risk. It fleshes out key concepts related to bankrupt, introduces financial analysis like a instrument of evaluation enterprise financial situation and specifically deals with prediction bankruptcy models. Metodology of model construction is introduced and ROC curves as an efficiency testing method. Case study makes evaluation of accuracy for five chosen models in sector small and medium enterprises manufacturing industry of central and eastern Europe. Concluding part narrates possibility modification of models for accuracy increase.
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Continual double-helicoidal mixer
Černý, Jan ; Malach, František (referee) ; Malášek, Jiří (advisor)
This work focuses on the process of mixing particulate materials and the design of the screw mixer for this activity. The theoretical part describes the mixing and properties of particulate matter. Subsequently, individual devices serving for different types of mixing are analyzed. The practical part contains calculations of the main dimensions and the required power consumption. The choice of suitable drive, bearings and gear is followed. Finally, the analysis of the blade shaft load and the strength analysis of the mixer blade using Autodesk Inventor are performed. Part of this work is enclosed drawing documentation of equipment assembly and selected partial components.
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Engine Motormanagement Software
Huška, Lukáš ; Kuchyňková, Hana (referee) ; Hájek, Vítězslav (advisor)
This master thesis deals with ignition systems which are used in cars vehicles with gas engines and also with setting of the best moment of ignition of gasoline-air mixture in cylinders of engine. Ways of gas injection at diesel engines and their control systems are also described in this thesis. Next chapter deals with control unit and describes main actions which are necessary for today’s motor vehicles. As illustration is used example of succession of actions which are necessary for calculation and setting regular value of pre-ignition. At the end is shown animation, which can be used for practice lessons in a subject Automobile Electric and Electronic Systems as a example. It will simplify understanding of described activities which are all accomplished by central control unit. For purposes of laboratory lessons is in this thesis also discussed measuring of engine performance with changes of parameter of central control unit.
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Stress and mobbing in SMEs
PLZÁKOVÁ, Kristýna
The aim of this diploma thesis is to assess stress and mobbing in small and medium sized enterprises and to make suggestions for possible future changes that would improve and eliminate stress and mobbing in SMEs. Furthermore, a questionnaire survey was used to determine the current state of stress and mobbing in SMEs. Subsequently, the questionnaire, which was completed by the employees of the selected SMEs, was quantitative in nature and included closed, semi-open, and open-ended questions in an electronic format. The research focused on stress factors, stress symptoms, and anti-stress techniques as well as on mobbing or bossing in the workplace. The paper concludes with proposing recommendations and solutions for SMEs dealing with stress and mobbing that companies can use to improve the current situation.
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Three Essays on Asymmetric Information in SME Finance and Microfinance
Wang, Yao ; Drábek, Zdenek (advisor) ; Janda, Karel (referee) ; Brada, Josef C. (referee) ; Kutan, Ali M. (referee)
This dissertation thesis consists of three essays on asymmetric information problem in small and medium sized enterprises (SMEs) finance and Microfinance. The aim of the thesis is to address the key problem in the credit rationing in the SME finance and microfinance and strive to improve the credit analyzing model with the help of soft information. The first essay investigates the factors that hinder the growth of SMEs using a World Bank dataset, and access to finance is found to be their biggest constrain to growth. Asymmetric information between small business owners and banks generates high interest rates, complex application procedures and high collateral requirements, which are found to be the biggest obstacles business owners face when they seek external financing. Small business owners who cannot get loans from banks will turn to microfinance as an alternative source of funds. In the second essay, a new dataset from disintermediated Peer to Peer (P2P) lending market is used to investigate credit rationing efficiency when there is no financial intermediary. The results show the existence of adverse selection where investors are predisposed to making inaccurate diagnoses of signals and gravitate to borrowers with low creditworthiness, while inadvertently screening out those with high...
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The current effectivness of bankruptcy prediction models in the conditions of Central and Eastern Europe
Honzíček, Štěpán ; Kuběnka,, Michal (referee) ; Karas, Michal (advisor)
Bachelor’s thesis describes issues of bankruptcy risk. It fleshes out key concepts related to bankrupt, introduces financial analysis like a instrument of evaluation enterprise financial situation and specifically deals with prediction bankruptcy models. Metodology of model construction is introduced and ROC curves as an efficiency testing method. Case study makes evaluation of accuracy for five chosen models in sector small and medium enterprises manufacturing industry of central and eastern Europe. Concluding part narrates possibility modification of models for accuracy increase.
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