|
|
Modal Analysis of the Classical Guitar Bridge
Ondečko, Adam ; Votava, Tomáš (referee) ; Hájek, Petr (advisor)
The bachelor thesis deals with the determination of the natural freqvencies and mode shapes of a classical guitar bridge and their influence on the function of the guitar. The function of the guitar is described by the oscillations of the individual oscillators: the strings, the air in the cavity of the guitar, the top and bottom plates, and then by their oscilation as a system. In the bachelor's thesis the roles of the guitar bridge are discussed and the different types of guitar bridges are presented. In the thesis, the guitar bridge is considered as a separate component and as part of the guitar's top plate. The mode shapes and natural freqvencies are obtained using modal analysis with the use of computational modelling using the finite element method. The natural freqvencies are determined for 2 types of guitar bridges, the effect of the guitar bridge on the mode shapes and natural freqvencies of the guitar top plate is further evaluated. The natural freqvencies of the classical guitar bridge affect the tone quality and the duration of oscilation of the string. Tones close to the natural freqvencies of the guitar bridge sound louder and last shorter amount of time than the others. The guitar bridge changes the stiffness of the top plate and thus influences its mode shapes and freqvencies.
|
|
|
Harmonic Analysis of the Double Bass Bridge
Čalkovský, Lukáš ; Votava, Tomáš (referee) ; Hájek, Petr (advisor)
This bachelor's thesis focuses on the research of string instruments and their mechanical properties. It explores the double bass bridge and its importance. On a model created in the SolidWorks program, modal analysis was performed using the ANSYS software, which determined the frequencies and shapes of the individual modes. Harmonic analysis was also performed and analysed. Part of the investigation was to analyze the possible cause of the formation of so-called wolf tones. The double bass bridge does not exhibit any special characteristics in the double bass range, so it is not the cause of this anomaly.
|
|
|
Stress-strain analysis of skull implant with fixators
Machala, Karel ; Votava, Tomáš (referee) ; Marcián, Petr (advisor)
A skull implant with fixators is used for the reconstruction of a damaged area of the skull, where a defect has occurred due to traumatic injury or disease. Nowadays, the production of a skull implant is preoperatively planned and employs modern technologies to achieve a patient-specific, customized approach. However, the manufacturing process of accurately fitting skull implants is associated with the challenge of achieving geometric precision and potential complications. The mechanical behaviour of the skull implant within the defect is a crucial factor that influences its functionality. This bachelor's thesis presents a comparison of distinct models of skull implant geometry at the interface between the implant and bone tissue, based on stress-strain analysis. Stress-strain states are determined using computational modelling utilizing the finite element method. Three variations of skull geometry models with the skull implant, considering different interfaces between the implant and bone tissue, were analysed. Additionally, for result comparison, a reference model of a skull without a defect was solved and analysed. The values of implant displacement were higher in cases where a gap was created at the interface between the implant and bone tissue. The stress values on the fixators were higher for the model variations with a gap created at the interface between the implant and bone tissue.
|
|
|
Stress-Strain Analysis of Plate for Fixing Proximal Tibial Fracture
Votava, Tomáš ; Chamrad, Jakub (referee) ; Marcián, Petr (advisor)
This master thesis is focused on stress-strain analysis of tibia with fixed proximal tibial fracture. Two types of fixation were considered, for each one two variants of solution were made. In the first part of this theses is presented a review of available literature connected with stress-strain analysis of tibia with fixed proximal tibia fracture. Next one is presented a research study of anatomy and biomechanics focused on lower limb. In the last part of research part are presented proximal tibial fractures and way of their fixation. Computational modeling using finite element method was used as solution method of stress-strain states. ANSYS software was used for solution. Total displacement, contanct pressure between femoral articular surface and meniscus, stress on plate and screws and strain in tibial bone tissue were analysed. Assesment of bone tissue state was made on the basis of Frost's hypothesis.
|
|
|
Determination of mechanical properties of cancellous bone tissue of skull bone
Votava, Tomáš ; Borák, Libor (referee) ; Marcián, Petr (advisor)
This bachelor thesis is focused on determination of mechanical properties of cancellous bone tissue of cranial bone. In research part of this study are described methods of medical imaging, mechanical properties of cranial bone tissue and anotomy of skull. Next one are described studies focused on determination mechanical properties of cancellous bone. Finally are decribed histomorphometric parameters and their measurement using software I$mageJ2$ and plugin $BoneJ2$. In practical part of this thesis, there are described measurement procedure, measurement results, 3D geometry modelling procedure by reconstruction micro-CT images and determination of mechanical properties solved by computational modeling using FEM. Five speciments are analyse predominantly from os occipitale. On first specimen is analyzed influence of thresholding settings.
|
|
|
Analysis of implementation of governmental drug policy in Cheb region
Votava, Tomáš ; Radimecký, Josef (advisor) ; Běláčková, Vendula (referee)
The purpose of this thesis consists in describing and analyzing the state of implementation of anti-drug policy of the Government of the Czech Republic at the local level and in proposing possible measures to improve such state. Specifically, the Cheb region in Karlovy Vary Region is involved. In this bachelor's thesis, the anti-drug policy is described in its basic approaches, principles, international cooperation and institutional background and important documents. In the thesis, we also deal with the issue of the Czech drug scene, how and by which it was influenced, and how it was reflected in the anti-drug policy of the Czech Republic. It is later described in more detail in its coordination, strategy a respective documents. At the regional level, the thesis analyses the state of implementation of anti-drug policy of the Government of the Czech Republic, in particular with regard to its coordination and institutional background. The identified weaknesses of implementation of anti-drug policy in the Cheb region include financing drug services, lack of interest of the political representatives of cities and communities in anti-drug policy, non-existence of a specialized subsequent care facility and specialized out-patient care for people addicted to drugs, existence of a single K-centre in the...
|
|
|
Stress-strain analysis of skull implant with fixators
Machala, Karel ; Votava, Tomáš (referee) ; Marcián, Petr (advisor)
A skull implant with fixators is used for the reconstruction of a damaged area of the skull, where a defect has occurred due to traumatic injury or disease. Nowadays, the production of a skull implant is preoperatively planned and employs modern technologies to achieve a patient-specific, customized approach. However, the manufacturing process of accurately fitting skull implants is associated with the challenge of achieving geometric precision and potential complications. The mechanical behaviour of the skull implant within the defect is a crucial factor that influences its functionality. This bachelor's thesis presents a comparison of distinct models of skull implant geometry at the interface between the implant and bone tissue, based on stress-strain analysis. Stress-strain states are determined using computational modelling utilizing the finite element method. Three variations of skull geometry models with the skull implant, considering different interfaces between the implant and bone tissue, were analysed. Additionally, for result comparison, a reference model of a skull without a defect was solved and analysed. The values of implant displacement were higher in cases where a gap was created at the interface between the implant and bone tissue. The stress values on the fixators were higher for the model variations with a gap created at the interface between the implant and bone tissue.
|
|
|
Modal Analysis of the Flute
Vojtovič, Adam ; Votava, Tomáš (referee) ; Hájek, Petr (advisor)
The presented bachelor thesis deals with an influence of a fundamental shape and partial sections of flute on frequency of tones. A simple flute is designed and made according to the given formulas. The functionality of the flute is verified by measuring frequencies of each tone. These frequencies are compared with values given analytically and also with values of natural frequencies calculated by finite element method. General information about wind instruments is included in the thesis, too. Besides the clarification of fundamental principles of function of wind instruments, there are also derived fundamental formulas for calculation of natural frequencies of tubes.
|
|
|
Exchange rate risk in the execution of payment transactions in the Chinese yuan and the possibility of its hedging
VOTAVA, Tomáš
This diploma thesis analyses an exchange rate risk of Czech companies related with business transactions in Chinese yuan in specific type examples and determines possibilities of an exchange rate risk hedging. In its theoretical part the diploma thesis generally describes issues of the international trade, China, the Chinese yuan, the exchange rate risk and the hedging. In its practical part the work models and analyses three business transactions in the Chinese yuan for the purpose of analysis of the exchange rate risk using fictitious companies and a simulation of their management behaviour including making wrong steps. Next, the work analyses a hedging offer from banks and non-banking companies in the Czech Republic. Based on the findings, the diploma thesis proposes if and how the fictitious companies should use the exchange rate risk hedging in order to minimalize an exchange rate loss and suggests the path leading to the exchange risk management optimization of companies for example using sophisticated risk management methods or entering the financial markets. Last but not least, modelled transactions are tested by E-start application in order to propose an optimization in case of using of the application by fictitious companies.
|
|
|
Stress-Strain Analysis of Plate for Fixing Proximal Tibial Fracture
Votava, Tomáš ; Chamrad, Jakub (referee) ; Marcián, Petr (advisor)
This master thesis is focused on stress-strain analysis of tibia with fixed proximal tibial fracture. Two types of fixation were considered, for each one two variants of solution were made. In the first part of this theses is presented a review of available literature connected with stress-strain analysis of tibia with fixed proximal tibia fracture. Next one is presented a research study of anatomy and biomechanics focused on lower limb. In the last part of research part are presented proximal tibial fractures and way of their fixation. Computational modeling using finite element method was used as solution method of stress-strain states. ANSYS software was used for solution. Total displacement, contanct pressure between femoral articular surface and meniscus, stress on plate and screws and strain in tibial bone tissue were analysed. Assesment of bone tissue state was made on the basis of Frost's hypothesis.
|
guest ::
RSS feed.