The paper presents an issue of determination of the vertical index error of spatial optical scanners. The procedure for numerical calibration is presented and the methodology is verified with experimental data. The proposed procedure is basically intended for numerical calibrations of measured point-cloud data, and also to improve the output quality and to eliminate costs of mechanical calibrations of optical scanners. and V práci je analyzována problematika určení velikosti chyby čtení svislého úhlu při měření prostorovými optickými skenery. Je představen postup jejího numerického určení a metodika je aplikována a ověřena na experimentálních datech. Navržený postup může sloužit k numerickým kalibracím měřených dat mračen bodů, výrazně zvýšit kvalitu výstupů, a také eliminovat náklady vybrané mechanické kalibrace optických skenerů.
The paper presents results of investigations on modeling and optimizing dynamic features of drive systems in order to minimize amplitudes of forces occurring in kinematic pairs of an electromechanical system with an ansynchronous motor and a vector control unit. The genetic algorithm was applied for optimization of design features of the system. The obtained results of numerical calculations confirmed the accuracy of the applied models and research methods for estimation of dynamic feature of drive systems. The set of design variables selected in the optimization process contained parameters describing design features of gear shafts and settings of control units. and Obsahuje seznam literatury
Optimization methods are used to estimate parameters required for routing floods through open compound channels. Besides initial and boundary flow conditions, data required especially include, crosssectional area (A) of flow and conveyance (K) as functions of flow depth (y) for a representative crosssection of the study reach. Thus, instead of optimizing upon channel's geometric and hydraulic parameters, optimization is performed upon non-physical parameters in assumed A(y) and K(y) relationships. The optimization method selected for this application is the Nelder and Mead Simplex Algorithm. The objective function is expressed in terms of the relative differences between observed and simulated stages and discharges, which are evaluated based on the complete numerical solution of St Venant equations. This approach to formulating the optimization problem was applied to unsteady flow data sets for an experimental reach of the River Main in Northern Ireland. Based on statistical analysis, simulated and observed stages were found to be in good agreement. and Parametre potrebné pre kvantifikáciu transformácie povodňových vĺn v otvorených, zložených kanáloch, boli určené optimalizačnou metódou. Okrem počiatočných a okrajových podmienok sú potrebné ďalšie údaje, vrátane plochy priečneho rezu prúdom (A), ako aj vodivosť časti toku (K) ako funkcie hĺbky (y) pre reprezentatívny priečny rez. Namiesto optimalizácie geometrických a hydraulických parametrov kanála, optimalizácia sa vykonala pre nefyzické parametre, predpokladajúc závislosti A(y) a K(y). Vybranou metódou optimalizácie je Nelderov a Meadov Simplex Algoritmus. Funkcia je vyjadrená pomocou relatívnych rozdielov medzi pozorovanými a simulovanými vodnými stavmi a prietokmi, ktoré boli vyčíslené numerickým riešením rovníc St. Venanta. Tento spôsob formulácie optimalizačného problému bol aplikovaný na údaje pre neustálené prúdenie v experimentálnom priamom úseku rieky Main (River Main) v Severnom Írsku. Štatistickou analýzou bolo zistené, že simulované a merané vodné stavy boli veľmi blízke.
This work describes a quantitative evaluation of interference patterns applied for testing of optical surfaces. The proposed method is based on the correlation between measured and virtual (nominal) interferograms and employment of mathematical nonlinear optimization. In contrast to most of common phase evaluation methods the proposed method does not need a detailed analysis of the interference patterns and phase unwrapping. The deviation of the measured surface from its nominal shape is modeled using a suitable function with unknown parameters, which are calculated by optimization of the merit function. The merit function is the correlation coefficient between measured and nominal interferogram, which characterizes the similarity of both interferograms. The functionality of the method was verified both by computer simulations and practical experiments. The method is applicable for the interferometric testing of flat, spherical and aspherical surfaces. and V práci je popsána metoda kvantitativního vyhodnocování interferenčního pole při kontrole tvaru optických ploch. Navržená metoda využívá korelace mezi měřeným a virtuálním (nominálním) interferogramem a matematických metod nelineární optimalizace. Na rozdíl od většiny běžně používaných metod nevyžaduje navržená metoda detailní analýzu interferenčního pole a odstranění nespojitostí fázových hodnot (tzv. phase unwrapping). Odchylka kontrolované plochy od jejího nominálního tvaru je modelována pomocí vhodné funkce s neznámými parametry, které jsou získány optimalizací meritní funkce. Za meritní funkci je zvolen korelační koeficient mezi měřeným a virtuálním (nominálním) interferogramem, který charakterizuje podobnost obou interferogramů. Funkčnost metody byla ověřena jak pomocí počítačových simulací, tak i na reálných případech měření. Metoda je použitelná pro interferometrickou kontrolu rovinných, sférických i asférických ploch.
Gearboxes and similar machines containing rotating parts are complex systems with complicated structure and couplings. Generally they can be decomposed into more simple subsystems. These subsystems are usually rotating shafts with gears joined
by gear couplings and housing coupled with rotating shafts by bearings. The paper is aimed at the mathematical modelling of gearboxes with spur helical gears considered including their interior rotating shaft system and housing. The used bearing model
respects real number of rolling elements and roller contact forces acting between the journals and the outer housing. The model of a complete gearbox is created using the modal synthesis method. The kinematic transmission errors in gear couplings are viewed as sources of excitation. Vibration and noise analysis of the gearbox housing is performed by means of the created model. Four types of objective functions suitable for optimization from the radiated noise point of view are proposed. The presented methodology is applied to the simple test-gearbox. and Obsahuje seznam literatury
Solar engine is discussed as integration of solar collector with linear heat loss and Curzon-Ahlborn engine is considered. This simple endoreversible model is used to discuss some applications of results of endoreversible heat engine in the field of solar engine. Optimum operating temperature of the solar collector and relevant maximum overall efficiency of solar engine is calculated, the results being compared with those by the models where Carnot and Curzon-Ahlborn efficiences were used. Conclusions obtained for endoreversible model are used for simple optimal design of solar engine. The size of heat engine for a given solar collector is optimized. The investment costs of solar collector and heat engine per unit of output power are used as optimization criterion. and Obsahuje seznam literatury
The paper deals with design optimization of a capacitive micromachined switch consisting of a thin membrane suspended over a central conductor. The aim is to achieve as small necessary electrostatic pull-in force as possibble while ensuring fast switching. Optimum parameters are searched using fast linear and nonlinear beam models verified by the finite element method. and Obsahuje seznam literatury
Positive Position Feedback (PPF) is one of the most attractive vibration control method due to its stability and ease of implementation. On the other hand, low robustness makes the PPF design more complicated in multimodal control case. It is known that a little change in optimal parameters setup, especially the change in controller frequency, can strongly degrade the control effort. Thus knowing a good approximation of optimal PPF parameters can be very helpful in practical implementations and simplified analytical relations between optimal parameters and modal properties of the structure are inevitable for efficient control design. In this paper derivation of such relations is introduced, based on simplified transfer function of controlled structure. Furthermore influence of the parallel PPF controllers in multimodal vibration suppression is analyzed and formulae for optimal parameters updating are suggested. Optimal multimodal PPF control design is demonstrated on experimental example of vibration suppression of beam structure. and Obsahuje seznam literatury
Performance of any machine tool is, under certain technological conditions, limited by chatter, which occurs during machining. The limit between machining without and with chatter is called limit of stability. It is expressed by so called stable depth of cut, which is defíned under certain conditions. The article deals with the investigation of optimal modal parameters for machine tool models. The criterion for this optimum is the highest limit of stability.
The contribution deals with a deterministic-based structural optimisation (DBSO). The instroductory part of the paper covers a short overview of optimisation algorithms applicable to deterministic-based problems, general DBSO formulation and a target function(s) pattern for structural design. The following part gives attention to particular problem of general RC (reinforced concrete) cross-sectional design subjected to normal force and bending moments (ULS, i.e. ultimate limit state), where basic cross-sectional characteristics (cross-sectional dimensions, steel bars profiles and types of materials constitute an optimisation space with discrete attributes. The target function (including economical and ecological aspects) and principle problem solution(s) is defined and an illlustrative numerical example of a simple rectangular cross-section design is presented. The solution approach is further augmented to RC frame structures problems and a numerical example of a collector tube design is presented. and Obsahuje seznam literatury