A new model for propagation of long waves including the coastal area is introduced. This model considers only the motion of the surface of the sea under the condition of preservation of mass and the sea floor is inserted into the model as an obstacle to the motion. Thus we obtain a constrained hyperbolic free-boundary problem which is then solved numerically by a minimizing method called {\em the discrete Morse semi-flow}. The results of the computation in 1D show the adequacy of the proposed model.
In endoprosthesis surgery there are typically a high percentage of implant defects, these can lead to failure of the whole prosthesis. One type of total hip replacement function loss is acetabular cup loosening from the pelvic bone. This article examines manufacture perturbations as one of the possible reasons for this kind of failure. Both dimension and geometry manufacturing perturbations of ceramic head and polyethylen cup were analyzed. We find that perturbations in the variables analysed here affect considered values of contact pressure and frictional moment. Furthermore, contact pressure and frictonal moment are quantities affecting replacement success and durability. From obtained results we can recommend to fit head and cup with a clearance of between 0 mm andd 0.05 mm. We do not recommend using interference type of fit. Roundness perturbation of ceramic head should not exceed 0.025 mm. and Obsahuje seznam literatury
The presented work is focused on the biomechanical study of the dental disk implant. The first part of the study deals with the strain analysis of the affected bone tissue and the dental implant loaded in the coronoapical direction by force 190 N. The study includes three types of implant anchorge, four degrees (stages) of osseointegration and nine degrees describing the quality of the cancellous bone. Two types of the disk implant were researched: single-disk and double-disk implant. Biomechanical study of the implant was focused on a stress-strain analysis of the affected bone rissue. The highest influence on the stresses in the bone tissue was primarily an implant anchorage. By the application of correlation relationships between Young modulus and the apparent density of the bone tissue - which is measurable in patients - we achieved the variable presented in this study. and Obsahuje seznam literatury
The presented work follows the first part [1], which is focused on the analysis of bone tissue in terms of dependence of bone tissue 'quality' and its subsequent behaviour based on the stress around the disk implant when biting.
This second part is focused on the stress-strain analysis (and tolerability) of disk implants as loaded during the masticating process.
The study includes two types of disk implants (single-disk and double-disk), three types of anchorage, four degrees (stages) of osseointegration in three quality degrees of the cancellous bone. The study, as expected, has shown that the problematic area of he implants is a transition between the implant body and the disk component, where the equivalent stress in the analyzed implants reaches 700 MPa. and Obsahuje seznam literatury
The characterization of ultra-soft soil behavior is one of the most difficult challenges since the water content in such soils is very high. Hence, nondestructive or special measurement is required. Therefore, the behavior of untreated and treated ultra-soft soil was characterized using both miniature penetrometer and electrical methods. The ultra-soft soil was prepared with 2% to 10% bentonite. The soil with 10% bentonite was treated with 2% to 10% lime and with 1% to 10% polymer separately. The pH, CIGMAT miniature penetrometer, and electrical resistivity combined with the measured shear strength from the modified vane shear device were used to characterize the ultra-soft soils. The CIGMAT miniature penetrometer penetration varied linearly with the shear strength of the untreated and treated soft soils with 10% bentonite. Relative electrical resistivity decreased by 246% when the bentonite content was increased from 2% to 10% in the ultra-soft soil. The addition of 10% of the lime to the ultra-soft soil with 10% of bentonite content decreased the relative electrical resistivity by 171%. The addition of 10% of the polymer to the ultra-soft soil with 10% of bentonite content reduced the relative electrical resistivity by 545%. Power law, linear and hyperbolic models were used to predict the shear strength- electrical resistivity relationship for the untreated, lime-treated and polymer-treated ultra-soft soils respectively. The CIGMAT miniature penetrometer was modeled using 3-D axisymmetric finite element method, which predicted the penetration of CIGMAT penetrometer that agreed well with the experimental results of the ultra-soft soils.
The computational model of the reed-based element is in scope of this article. This element is studied for its potential suitability to generate an arfificial source voice. Compressed air is being used like a source of the energy to produce the voiced speech (similar to the healthy voiced speech). Two-way iteraction of solid and fluid part of the computational model has been considered for the solution. Computation has been performed by the finite element method (Ansys) and results have been processed by the sofsware MATLAB. Basic characteristics like a frequency spectrum and a fundamental frequency of generated source voice are evaluated. Relationship between deformation of the reed and the pressure in front of the reed is presented. This characteristic represents one of the basic phonation theories which are in our scope. This theory is based on the compressed air ‘bubble‘. and Obsahuje seznam literatury
Hyperspectral imaging as a tool for obtaining information about the world around us is rapidly developing field of modern technology. The desired information in such systems is obtained by processing ofstored spectral information of a measured scene. The main advantage of the hyperspectral systems is the use of a wide spectral range encompassing both the visible and adjacent spectral regions(primarily infrared). The main element in these systemsis a spectrally selective element which provides separation of the individual spectral components. This element can be based on number of physical principles, in this paper we will discuss the design and fabrication of a spectral element based on a diffraction grating. The main requirements for this system were: spectral division function for LWIR (7 mm - 14 mm), the highest possible efficiency in this spectral region with respect to the spectral emission of a black body with temperature 350 K, and avoidance of the restrictions given by the production. Design of the grating was done with the use of a scalar theory and the results were compared with RCWAand finite element method. Fabrication of the grating was carried out using single-point diamond turning. The grating was made of germanium. and Hyperspektrální zobrazování, jakožto nástroj pro získávání informací o světě kolem nás, je rychle se rozvíjející oblast moderní techniky. Požadovaná informace se v takových systémech získává zpracováním uložené spektrální informace z měřené scény. Jednou z výhod hyperspektrálního systému je užití širokého spektrální rozsahu obepínajícího jak viditelné, tak i přilehlé spektrální oblasti světla (především infračervenou). Hlavní prvek v těchto systémech je spektrálně selektivní člen zajišťující separaci jednotlivých spektrálních komponent. Tento člen může být založen na různých fyzikálních principech, v rámci tohoto příspěvku diskutujeme návrh a výrobu spektrálního elementu založeného na difrakční mřížce. Hlavní požadavky na tento systém jsou spektrálně selektivní funkce pro LWIR (7 mm - 14 mm), co možná nejvyšší účinnost v dané spektrální oblasti vzhledem k spektrálnímu vyzařování černého tělesa o teplotě 350 K a vyhnutí se omezení daných výrobou. Návrh mřížky vychází ze skalární teorie elektromagnetického pole a výsledek je porovnán s RCWA a metodou konečných prvků. Vlastní výroba mřížky se provedla jednobodovým diamantovým soustružením do germania.
We introduce a new way of computation of time dependent partial differential equations using hybrid method FEM in space and FDM in time domain and explicit computational scheme. The key idea is quick transformation of standard basis functions into new simple basis functions. This new way is used for better computational efficiency. We explain this way of computation on an example of elastodynamic equation using quadrilateral elements. However, the method can be used for more types of elements and equations.
Presented paper is focused on description of algorithm for fast analysis of leveling process in detail and on verification of obtained results. The main idea is based on using Finite Element Method (FEM) and solving its fundamental equation. The algorithm is programmed using software MATLAB. The program has modular structure, so it is not complicated to modify any setting or utility. Leveling process of long semi products respecting the Eulerian approach is considered. Curved material passes through laterally offset rollers so repeated elasto-plastic bending occurs. Plastic deformation causes redistribution of residual stress. The semi product is straightened when rollers are appropriately positioned. Given problem is complicated due to high inherent nonlinearity and sensitivity, caused by cyclic plasticity. Useful setting of the leveling machine is found by iterative process, based on input measured geometrical data and material characteristics. and Obsahuje seznam literatury
The problem of thermal fatigue in pipe connections under the influence of streams mixing is one of the most discussed problems on international conferences. Numerous failures occur in industry as a result of this damage mechanism. It is caused by frequent stress changes developed by an effect of non-stationary thermal fields. The degree of damage is greatly dependent on characteristic of material geometrical design of a pipe connection in operational conditions. The report is dealing with influence of temperature differences of mixing media streams upon pipe material damage cumulation. It is focused on a perpendicular T-junction made of ferritic steel, which is protected inside with an anticorrosive weld deposit from austenitic steel. Six cases of temperature differences will be considered for particular operational conditions with a step of 50 °C, and the damage cumulation process will be observed. Thanks to it, it will be possible to judge better the meaning of streams temperature differences. and Obsahuje seznam literatury