Browsing by Author "Šafářová, Veronika"
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- ItemComparison of methods for evaluating the electromagnetic shielding of textiles(2012) Šafářová, Veronika; Militký, JiříMaterials with electromagnetic shielding efficiency are widely used to attenuate the strength of electromagnetic fields as functional elements in electrotechnic devices and also as supporting elements for electromagnetic interference reduction. One of modern application is not only technical protection, but also protection of human being while operating specific electric equipments. In these days, instead of metallic shields it is more common to use various types of textile materials due to their desirable flexibility and lightweight. The results of shielding effectiveness measurements depend on the method, frequency and properties of the material itself. The current state of work in the field of standardization and measurement methods for the shielding effectiveness of thin planar materials is presented in this paper. Testing of textile samples shielding was performed by different methods and scope of application, their limitations and possibilities for comparison of results are discussed.
- ItemDevelopment of a hybrid electromagnetic shielding fabric(2011) Šafářová, Veronika; Militký, JiříAccording to World Health Organization [1], exposure to electromagnetic fields is not a new phenomenon. However, during the 20th century, environmental exposure to man-made electromagnetic fields has been steadily increasing as growing electricity demand, ever-advancing technologies and changes in social behavior. Everyone is exposed to a complex mix of weak electric and magnetic fields, both at home and at work. Sources of such emissions could include generation and transmission of electricity, domestic appliances and industrial equipment, telecommunications and broadcasting. If the electromagnetic waves are not isolated effectively, they will cause interference with each other and result in technical errors. If somebody gets exposed under the electromagnetic, radiate environment, physical harms may occur on human body [2,3]. Metal is considered to be the best electromagnetic shielding material due its conductivity and permeability, but it is expensive, heavy, and may also have thermal expansion and metal oxidation, or corrosion problems associated with its use. In contrast, most synthetic fabrics are electrically insulating and transparent to electromagnetic radiation [4]. In recent years, conductive fabrics have obtained increased attention for electromagnetic shielding and anti-electrostatic purposes. This is mainly due to their desirable flexibility and lightweight. One way how conductive fabrics can be created is by using minute electrically conductive fibers. They can be produced in filament or staple lengths and can be incorporate with traditional non-conductive fibers to create yarns that possess varying degrees of conductivity. Another way represents conductive coatings which can transform substrates into electrically conductive materials without significantly altering the existing substrate properties. They can be applied to the surface of fibers, yarns or fabrics. The most common are metal and conductive polymer coatings. In this paper, a hybrid electromagnetic shielding fabrics are introduced. An effect of metal content is studied and a form of relation between resistivity and total shielding effectiveness ST is proposed. First group of fabrics is made of hybrid yarns containing metal staple fibers, second group of fabric are polypropylene twill with mesh composed of hybrid yarns containing POP and metal fiber.
- ItemElectromagnetic field shielding fabrics with increased comfort properties(2013) Šafářová, Veronika; Militký, JiříThe 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.
- ItemElectromagnetic shielding properties of woven fabrics made from high-performance fibers(Sage Publications Ltd, 2014) Šafářová, Veronika; Militký, JiříThe 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.
- ItemMultifunctional metal composite textile shields against electromagnetic radiation-effect of various parameters on electromagnetic shielding effectiveness(John Wiley and Sons Inc., 2015) Šafářová, Veronika; Militký, JiříOver the last few years, there has been mounting concern about the possibility of adverse health effects resulting from exposure to radiofrequency electromagnetic fields, such as those emitted by wireless communication devices. For the reason given above, a demand for protection of human beings against influence of electromagnetic signals and troublesome charges, has been increasing. Therefore textile structures with increased electromagnetic shielding ability, which satisfy the requirements for casual dress or preserve air circulation at workplace, is suitable. This article presents the present state of fabrication and characterization of multifunctional light weight flexible fabrics with increased resistance to electromagnetic radiation while preserving basic properties of textile structures designated for clothing or technical purposes. In this article, an effect of metal content, a placement of conductive yarn, geometry, moisture content and correlation with frequencies is studied. In addition, percolation thresholds are identified and a form of relation between conductive component and total shielding effectiveness is proposed. © 2015 Society of Plastics Engineers.