Yarn hairiness characterization using two orthogonal directions

We demonstrate that one can adequately characterize Yarn hairiness by imaging the yarn along a single projection direction using coherent optical processing. A system that simultaneously characterizes the yarn hairiness along two orthogonal projection directions was constructed. Provided that a sufficiently high number of yarn segments are sampled, a strong statistical correlation is obtained between the results in each direction. The resulting images are generated using coherent optical signal processing with a Fourier high-pass spatial filter. This filter blocks the yarn core and produces a signal that highlights the sharp transitions in the transmission of the yarn. Essentially, only the small fibres responsible for the hairiness and the yarn core contours are present. Experimental results are presented for a 62-g/km yarn possessing a high degree of hairiness. Index Terms—Electronic instrumentation, optical sensors, orthogonal directions, signal processing, yarn hairiness.Fundação para a Ciência e a Tecnologia (FCT) - BD/19028/2004

A comparison of mass parameters determination using capacitive and optical sensors

This paper presents a comparison study between the use of 1mmresolution capacitive and optical sensors for the determination of yarn mass parameters. A parallel plate capacitive sensor to determine yarn mass variations and a yarn diameter and hairiness determination solution using optical sensors and integrating optical signal processing based on Fourier analysis are described. As there is a high correlation between yarn diameter and yarn mass, it is possible to determine yarn mass and infer variations in yarn diameter and vice versa. Moreover, by optically detecting the degree of yarn hairiness, one can quantify its influence on the capacitive sensor mass variation measurements. Here we present the results of a signal processing analysis and statistical description of measurements carried out in two 100% cotton yarns with a linear mass of 59 and 295 g/km performed in yarn system quality (YSQ) machine. We conclude that an accurate yarn characterization can be carried out using optical sensors alone, reducing system’s cost and complexity and increasing efficiency.Fundação para a Ciência e a Tecnologia (FCT) - BD/19028/200

Yarn diameter characterization using two orthogonal directions

We have used a coherent optical signal processing technique based on Fourier optics to characterize yarn diameter using a single projection.Fundação para a Ciência e a Tecnologia (FCT) - BD/19028/200

A comparison of mass parameters determination using capacitive and optical sensors

AbstractThis paper presents a comparison study between the use of 1mm resolution capacitive and optical sensors for the determination of yarn mass parameters. A parallel plate capacitive sensor to determine yarn mass variations and a yarn diameter and hairiness determination solution using optical sensors and integrating optical signal processing based on Fourier analysis are described. As there is a high correlation between yarn diameter and yarn mass, it is possible to determine yarn mass and infer variations in yarn diameter and vice-versa. Moreover, by optically detecting the degree of yarn hairiness, one can quantify its influence on the capacitive sensor mass variation measurements. Here we present the results of a signal processing analysis and statistical description of measurements carried out on a 100% cotton 295 g/km linear mass yarn. We conclude that an accurate yarn characterization can be carried out using optical sensors alone, reducing systems cost, complexity and increasing efficiency

Digital image processing and illumination techniques for yarn characterization

This paper describes various illumination and image pro- cessing techniques for yarn characterization. Darkfield and back-lit illuminations are compared in terms of depth of field tolerance and image quality. Experiments show that back-lit illumination is superior in terms of depth of field tolerance and contrast. Three different back-lit illumination configurations are studied: one simply employ- ing a light source placed behind the yarn, the other incorporating a field lens to increase the light intensity passing through the aperture, and the third using a mirror placed at 45° to the optical axis to enable imaging of two orthogonal views of the yarn core. Problems in defining the hair–core boundaries in high resolution yarn pictures are addressed and a filtering process is introduced for back-lit im- ages. A comparison of the diameter and diameter coefficient of variation percentage measurements for different illumination and im- age processing techniques is given for several yarn samples. The data are also correlated with Premier 7000 diametric irregularity tester and Uster Tester 3 irregularity measurements. © 2005 SPIE and IS&T

Evaluation of yarn characteristics using computer vision and image processing

Irregularity, hairiness and twist are among the most important characteristics that define yarn quality. This thesis describes computer vision and image processing techniques developed to evaluate these characteristics. The optical and electronic aspects such as the illumination, lens parameters and aberrations play crucial role on the quality of yam images and on the overall performance of image processing. The depth of field limitation being the most important restraint in yam imaging as well as image distortion in line scan cameras arising from digitisation and yam movement are modelled mathematically and verified through experiments both for front-lit and back-lit illuminations. Various light sources and arrangements are tested and relative advantages and disadvantages are discussed based on the image quality. Known problems in defining the hair-core boundaries and determining the total hairiness from yam images are addressed and image enhancement and processing algorithms developed to overcome these problems are explained. A method to simulate various yam scanning resolution conditions is described. Using this method, the minimum scanning resolution limits to measure the hairiness and irregularity are investigated. [Continues.

Hybridní tkané struktury

Tato disertační práce poskytuje podrobnější informace o vlastnostech čedičových vláken vedle běžně používaných vláken, a to pro návrh a vývoj hybridních tkaných textilií určených pro výrobu kompozitních materiálů, zejména betonu vyztuženého textilií (TRC). Zkoumány jsou různé kombinace čedičové hybridní tkaniny s ohledem na mechanické, tepelné, akustické, elektrické a jiné vlastnosti, přičemž vliv hybridizace a struktury tkaných textilií je studován detailněji. Mechanické vlastnosti jsou predikovány s použitím a strukturální modely korelovány s výsledky získanými z provedených experimentů. Čedičová vlákna jsou velmi perspektivním materiálem díky jejich ohnivzdornosti spojené s lávovým původem, vynikajícím mechanickým vlastnostem a relativně nízké ceně. Na druhou stranu, tato vlákna doposud nebyla podrobena rozsáhlejšímu průzkumu, protože je možno je považovat za relativně nový typ vlákna. V technických článcích je možno nalézt jen omezené množství údajů o jejich chování po zpracování, jež je spojeno se stárnutím materiálu. Disertační práce prozkoumává možnosti využití čedičových vláken v kombinaci s jinými typy přízí a následně také vliv hybridní tkané struktury na nosnost kompozitu a dobu jeho životnosti. V této studii je vyšetřeno nosné chování TRC kompozitu (kompozitní systém tvořený jemnozrnnou betonovou matricí a výztuží složenou z vysoce funkčních vláken zpracovaných do plošné textilie) při jednoosém namáhání tahem. Průzkum je zaměřen na výztužnou schopnost hybridní tkané struktury. Při začleňování textilní struktury do betonu je zřejmé, že veškeré příze nejsou impregnovány cementovou matricí kompletně, což vede k heterogenitě systému beton - příze přispívajícímu ke komplexní nosnosti a defektnímu chování TRC kompozitu. Hlavním cílem této práce je tedy průzkum hybridizačních efektů na nosné chování TRC kompozitu.This thesis conveys a better insight into characteristics of Basalt fibers specifically, alongside commonly used fibers to design and develop hybrid woven fabrics for TRC composite materials. Various combinations of basalt hybrid fabrics are investigated with respect to mechanical, thermal, acoustic, electrical and other functional properties. The influence of hybridization and structure of woven fabric is studied in detail. The tensile properties are predicted by using structural model and correlated to the results obtained through experiments. Basalt fibers are very promising materials due to their fire resistance related to magmatic origin, superior mechanical properties and relatively low cost. On the other hand, being a relatively new kind of fiber, they are still not studied extensively. There are very few indications in technical papers about their behavior after aging treatments. The current study investigates the possibility of using basalt with other types of yarns and consequently the effect of hybrid woven structure on load bearing capacity and durability. In the present work, the load-bearing behavior of Textile Reinforced Concrete (TRC), which is a composite of a fine-grained concrete matrix and a reinforcement of high-performance fibers processed to textiles, when exposed to uniaxial tensile loading was investigated. The investigations are focused on reinforcement of hybrid woven fabrics. When textile yarns are embedded in concrete, they are not entirely impregnated with cementitious matrix, which leads to associated heterogeneity of the concrete and the yarns to a complex load-bearing and failure behavior of the composite system. The main objective of the work is the investigation of hybridization effects in the load-bearing behavior of TRC

Microplastic pollution from synthetic textiles: quantitative evaluation and mitigation strategies

The present thesis focuses on microplastic pollution from synthetic textiles. Microplastics are defined as plastic fragments with dimensions less than 5 mm, which are gaining much attention due to their ubiquitous and possibly dangereous presence in marine environment. Washing processes of synthetic garments have been lately identified as responsible for about 35% of primary microplastic release in oceans and seas. Microplastics represent a threat for marine ecosystems, and consequently for humans, since they may be ingested by fauna, adsorb persistent organic pollutants and leach toxic additives. Moreover, recent concern has arisen regarding the possibility for humans to inhale microplastics released to air from wearing of synthetic garments, with still not understood consequences on health. In such scenario, this work has three major objectives: developing experimental procedures to quantify microfibres released to water and to air from synthetic clothes, investigating the role of textile characteristics and washing conditions in the release of microfibres, implementing mitigation strategies. First of all, two quantitative methods were developed to evaluate the amount of microfibres released during washing processes at lab and real scale. The two developed procedures were compared in terms of results, effectiveness, costs and time consume and proved to be a useful tool for the evaluation of the extent of the release from textiles, allowing the identification of specific trends in the microplastic release, as a function of the textile nature and geometry, different detergents and washing conditions. Then, a protocol involving tests with volunteers wearing commercial synthetic garments was set up to assess if microfibres are actually released by wearing clothes and if the quantities and dimensions pose a real threat for human health. Finally, mitigation actions were proposed, based on the development of innovative finishing treatments of synthetic textiles, aimed at creating a thin coating on the surface of fabrics that could protect them during the stresses of wearing and washing, reducing the release of microfibres. The ecosustainability of such treatments was ensured by using natural or biodegradable polymers as finishing materials, instead of the conventional synthetic ones. The effectiveness of such treatments in mitigating the release of microfibres was tested by washing tests at lab scale, showing a very promising reduction of almost 90% of microfibres released by untreated fabrics