Multiparametric curve fitting XV. statistical analysis and goodness-of-fit test by the least-squares algorithm MINOPT

Estimation of nonlinear regression quality leads to examination of quality of parameter estimates, a degree of fit, a prediction ability of model proposed and quality of experimental data. Statistical analysis serves for computation of confidence intervals of parameters and confidence bands, the bias of parameters and bias of residuals. Goodness-of-fit test examines classical residuals using various diagnostics and identifies influential points. Mentioned topics of nonlinear model building and testing contained in MINOPT program from CHEMSTAT package are illustrated

Optické vláknové senzory fyzikálních veličin.

Tato disertační práce je zaměřena na využití vysoce dvojlomných optických vláken v optických vláknových senzorech, především ke sledování teploty. K tomuto účelu se využívá spektrální interferometrie v bílém světle. Práce uvádí principy šíření elektromagnetického pole v optických vláknech, popisuje speciální optická vlákna a analyzuje spektrální interferenci vln na výstupu experimentální sestavy. Dále jsou prezentovány a diskutovány výsledky měření spektrální interference s využitím různých experimentálních sestav a typů dvojlomných vláken. V experimentech se využívá interference optických vln, přičemž jde o ortogonálně polarizované vidy dvojlomných optických vláken, nebo o řádnou a mimořádnou vlnu dvojlomného krystalu. Výhodné je, že se jedná o vlny ve viditelné a blízké infračervené oblasti spektra, což snižuje nároky na použitý světelný zdroj i detektor. Popisované experimenty ukazují, jak lze využít optická vlákna v senzorech pro měření různých fyzikálních veličin, a demonstrují možnost využití Vernierova jevu ke zvýšení citlivosti daného měření. Kromě optických vláknových senzorů teploty se práce v experimentální části zabývá také optickým senzorem posunutí využívající Michelsonův interferometr ve standardní konfiguraci a v konfiguraci využívající Vernierův jev ke zvýšení citlivosti měření.This thesis deals with uzilization of highly birefringent optical fibers in fiber optic sensors, mainly in temperature sensing. For this purpose white-light spectral interferometry is exploited. The thesis introduces principles of guiding of electromagnetic field in optical fibers, describes special optical fibers and analyzes spectral interference of waves at the output of an experimental setup. Furthermore, results of measurements of spectral interference with utilization of diverse experimental setups and birefringent fibers types are presented and discussed. In experiments, interference of optical waves is exploited, whereas these are orthogonally polarised modes of birefringent optical fibers or ordinary and extraordinary wave of a birefringent crystal. It is advantageous that these waves are in visible or near infrared part of spectrum which lowers demands on used light source and detector. Described experiments show how optical fibers can be used in sensors for sensing diverse physical quantities and demonstrate a possibility of utilization of the Vernier effect for given measurement sensitivity enhancement. Beside optical fiber temperature sensors the thesis in experimental part also deals with an optical displacement sensor utilizing a Michelson interferometer in a standard configuration and in a configuration utilizing the Vernier effect to measurement sensitivity enhancement.USP - Univerzitní studijní programyvyhově

Ultimate strength of fibres and fibrous bundles

The main models for description of fibers ultimate strength based on the probabilistic approach are discussed. For identification of fiber strength type and estimation of corresponding parameters the modified quantile regression is proposed. The bundle strength predictions based on the simplest approach of uniform share of loading and knowledge of fiber strength distribution is described. The simulation approach starting from reliability of parallel system is used as well. These predictions are used for estimation of basalt roving strength. Predicted values are compared with experimental data

Dynamic analysis and prototyping of coilgun

Tato práce se zabývá popisem principu Gaussovy pušky. Je zde popsán fyzikální princip, na kterém zařízení funguje, provedení konstrukce a její výhody a omezení. Dále je vytvořen výpočtový model v prostředí Matlab Simulink, který simuluje chování projektilu během výstřelu. Na základě tohoto modelu je navržen a zkonstruován prototyp Gaussovy pušky. Prototyp je následně testován a porovnáván s výpočtovým modelem pro určení celkové účinnosti vytvořené pušky.This thesis deals with the description of the Gaussian rifle principle. It describes the physical principle, on which the device works, the design of the structure and its advantages and limitations. Furthermore, a computational model is created in the Matlab Simulink environment, which simulates the behavior of a projectile during a shot. Based on this model, a prototype Gaussian rifle is designed and constructed. The prototype is then tested and compared with a computational model to determine the overall effectiveness of the created rifle.

Multiparametric curve fitting XIV. Modus operandi of the least-squares algorithm MINOPT

Hybrid least-squares algorithm MINOPT for a nonlinear regression is introduced. MINOPT from CHEMSTAT package combines fast convergence of the Gauss-Newton method in a vicinity of minimum with good convergence of gradient methods for location far from a minimum. Quality of minimization and an accuracy of parameter estimates for six selected models are examined and compared with different derivative least-squares methods of five commercial regression packages

Tensile, surface and thermal characterization of jute fibres after novel treatments

Jute fibres have been treated with enzymes, CO2 pulsed infra red laser, ozone and plasma to study the effect of these treatments on their tensile, surface and thermal properties. Surface characteristics of jute fibres have been examined by scanning electron microscopy and Fourier transform infrared spectroscopy while thermal characteristics using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). No significant reduction in the tensile strength of treated jute fibres is observed. Changes in the surface chemical composition and increase in surface roughness are observed after the treatments. DSC data show a decrease in decomposition temperature of hemicellulose of all treated jute fibres. DSC and TGA analyses show no marginal difference in the cellulose decomposition temperature of untreated and treated jute fibres. The study shows a change in the surface chemistry and morphology after treatments without any substantial change in the thermal stability and tensile properties of jute fibres. The study also reveals the potential use of infrared laser and ozone treatments for the modification of natural fibres besides the conventional treatments using enzymes and plasma

Ultimate mechanical properties of thermally exposed basalt filament yarns

Fresh basalt fibers are practically amorphous. Due to high temperature action these fibers have ability to partially crystallize. This form of basalt fibers can be more brittle and their strength can be too low. In this contribution the strength of basalt filament yarns is investigated at room temperature and after tempering to the 50, 100, 200, 300, 400 and 500°C. Structural changes of fibers are identified by scanning electron microscopy. The strength drop of basalt filaments after long term temperature exposition is described by the linear spline nonparametric model

Some open problems of hand evaluation

This report discusses the reproducibility of subjective hand evaluation and the prediction, of subjective hand. For reliable subjective hand evaluation, the reproducibility of results and their good presentation are important. An approach based on categorized variables is used. The ordinal median and a 95% confidence interval are applied. The set of fabric properties associated with hand is specified. The method of forecasting subjective hand based on these properties is described. The whole procedure is demonstrated in relation to polyester/wool fabrics for men's winter suits

Electromagnetic shielding properties of woven fabrics made from high-performance fibers

The expansion of the electronic industry and the extensive use of electronic equipment in communications, computations, automations, biomedicine, space, and other purposes have led to problems such as electromagnetic interference of electronic devices and health issues. For the reasons given above, the demand for the protection of human beings and sensitive electronic and electrotechnic appliances against the undesirable influence of electromagnetic signals and troublesome charges has been increasing. This paper presents the present state of fabrication and characterization of multifunctional high-performance metal/m-aramid hybrid fabrics with increased resistivity to electromagnetic smog while preserving basic properties of textile structures designated for clothing or technical purposes. In this paper, hybrid electromagnetic shielding fabrics made of high-performance fibers are introduced. An effect of metal content is studied and a form of relation between resistivity and total shielding effectiveness is proposed. Furthermore, chosen mechanical properties of developed fabric are evaluated