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

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

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

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

Numerical and experimental study of the shielding effectiveness of hybrid fabrics

The electromagnetic interference shielding efficiency measurement needs to use special devices and in addition results are dramatically affected by applied measuring method. Measurements of surface or volume resistivity are simpler. It is known from theory that it is possible to measure characteristics of electrical part of electromagnetic field only at sufficiently high frequencies and therefore there should be mathematical relation between total shielding effectiveness SE [dB] and fabric resistivity or conductivity. One of modern application of materials with increased electromagnetic shielding efficiency is not only technical protection, but also protection of human being while operating specific electric equipments. The main aim of this work is investigation of the form of relation between electrical characteristics and total shielding effectiveness SE for special types of fabrics containing extremely thin metal fibers in its structure

Electromagnetic field shielding fabrics with increased comfort properties

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 reasons given above, a demand for protection of human being, sensitive electronic and electrotechnic appliances against undesirable influence electromagnetic signals and troublesome charges raised. This paper presents the present state of a fabrication and characterization of multifunctional metal hybrid fabrics with increased resistivity to electromagnetic smog at conserving basic properties of textile structures designated for clothing purposes. The parameters influencing electromagnetic (EM) shielding properties of the hybrid fabrics were investigated. It was shown that the EM shielding effectiveness of the fabrics could be tailored by modifying the metal content, metal grid size and geometry. Furthermore, correlation between electrical properties and EM shielding effectiveness and comfort properties was studied. © (2013) Trans Tech Publications, Switzerland