Yordan Kyosev

Algorithm for Solving Max-product Fuzzy Relational Equations

Analytical methods are proposed for solving fuzzy linear system of equations when the composition is max-product. These methods provide universal algorithm for computing the greatest solution and the set of all minimal solutions, when the system is consistent. In case of inconsistency, the equations that can not be satisfied are obtained.

Fuzzy Relational Calculus: Theory, Applications and Software(With CD-ROM)

Fuzzy Relations. Direct Problem Resolution Fuzzy Relation Equations Fuzzy Relational Inclusions Fuzzy Linear Systems -- Dual Approach Direct and Inverse Problems in Intuitionistic Fuzzy Relational Calculus L-Fuzzy Finite Machines Fuzzy Languages in Syntactic Pattern Recognition Applications as Inference Engine Software Description

Geometry modelling of warp knitted fabrics with 3D form

Warp knitted fabrics are widely used in medical and technical applications, as well as for clothing textiles. To predict their properties, it is useful to have knowledge about the yarn geometry and the yarn interactions within these fabrics. The geometrical modelling of warp knitted structures from single bed knitting machines is documented in the literature. This text concentrates on a computation of the geometry of warp knitted structures, which have complex 3D forms or which are draped over similar ones. The topological information about the structure produced on the machine, is used to create the basic geometry of this structure. After creating the basic geometry, it is transferred to a 3D deformed state of the relaxed fabric. The paper starts with a short overview of the research papers about simulation of warp knitted structures. General theoretical remarks about the transformation from basic structure to 3D structure are given. Examples of spacer fabric with constant or non-constant thickness and tubular fabrics are included. All the results concentrate on the topological representation of the geometry and at this stage do not take into account the influence of internal and external forces exerted on the fabric.

3D Modeling of Plain Weft Knitted Structures of Compressible Yarn

In this paper two methods for 3Dimensional modeling of the plain weft knitted structures are presented. The aim is models to be more realistic concerning yarn cross section properties. The first model is based on the assumption that yarn cross section changes to ellipse-like form in the areas with high curvature. The second one is a discrete particle model of the loops, which takes into account the local changes of the yarn following from the contact forces. It calculates actual yarn geometry on the contact places iteratively, as general nonlinear compression behavior of the yarn is assumed.

Generalized geometric modeling of tubular and flat braided structures with arbitrary floating length and multiple filaments

This paper provides a critical overview about the state of the art in the area of three-dimensional modeling of braided structures. It gives a generalized geometrical approach for modeling braided structures with arbitrary floating length and filaments in the yarn. The approach is tested with large set of structures of different types. Subsequently, one of the simulated geometries is compared with the real geometry of braided tube.

Modelling and visualization of knitted fabrics

Abstract: In this chapter an overview is presented of modelling methods for warp and weft knitted structures. The chapter begins with basic information about knitted structures, their classifications and the observation scales. After this introduction, the basic structural elements as main modelling elements at the meso-scale level are explained, followed by the basic problems and required steps during the modelling. The model generation is discussed in three main parts, checking the input data, topology generation and mechanics of the structure. For the mechanical model, two paths are presented, continuum and discrete. Some additional problems connected with the form of the yarn cross-section, yarn unevenness and contact treatment are followed. Finally, different ways of postprocessing the data are explained, including yarn volume rendering, visualization and other calculations, based on the modelled data and some application areas.

Experimental investigation of the influence of wool structures on the stab resistance of woven body armor panels

In the production of body armor panels, multilayer aramid fabrics are normally used. A main problem of these panels is the high weight and consequential lower comfort for the wearer. In a recent survey it was shown that most officers in the United States would prefer an improved comfort and also reduced weight in their ballistic vests. To reduce layers with a concomitance of the same safety standards, the panel has to be improved. One solution is to reduce the slippage of the yarns during the penetration of the knife and with this to increase the absorbed impact energy. The tests showed that the placement of a layer of wool fabric on the top of the aramid panel changes the penetration behavior. The main goal of this work is the investigation of the influence of the woven wool structure over the penetration of aramid panels. For this investigation, the stab resistance of five aramid fabrics with different properties and patterns combined with one layer of wool on the top and bottom of the panel has been tested and compared against pure aramid panels, according to the VPAM test instruction “Stab- and Impact Protection”. In addition, an optical evaluation of the stab tests has been done using a high-speed camera. Also, the stab recess in the aramid layers was evaluated optically, using a digital microscope. The experimental results confirm that wool can increase the stab resistance of body armor panels, but results are dependent on the properties and pattern of the aramid fabrics, too.

Development of Machine Configuration for T- and I-Profiles and Their Topological Modelling

This works presents a numerical investigation about the production and simulation of braided products with complex cross section. The geometrical modelling of tubular and flat braids is already well described in the literature and implemented in several scripts and commercial software like TexMind Braider. In the literature are reported as well several works about the modelling of 3D braided structures, created using different 3D braiding techniques. For the case of complex maypole braiding machine with horn gears are reported some works with the software TexMind Braiding Machine Configurator, which emulates the carrier motion for the creation of the 3D geometry of the braids. This work presents evaluation of the possibilities of the software for designing machines with large number of horn gears in custom arrangements and at the same time presents the results of a large set of tests of the possible combinations for arrangements of horn gears with different size for the production of complex multilayer braided structures like T-, and double-T-profiles. The investigation shows, that the possibilities for carrier arrangement are directly connected with the topology of the tracks of these carriers and for structures with multiple tracks more empty places in the arrangement is required. For the cases, where for such structures suitable machine configuration and carrier arrangement is found, an simplistic 3D geometry of the braid is generated and can be used for FEM calculations, relaxation and other computations of the properties.

Heat and mass transfer through outerwear clothing for protection from cold: influence of geometrical, structural and mass characteristics of the textile layers

This paper presents a comprehensive experimental study, conducted on a series of woven and non-woven fabric samples from different materials (cotton, polyester, and polyamide) and 14 three-layer systems of textile materials, used for production of outerwear clothing for protection from cold. Heat and mass transfer properties, related to the thermophysiological comfort of the outerwear clothing, namely conductive thermal resistance, water vapor resistance, relative water vapor permeability, air permeability, accumulative one-way transport of liquids, and overall moisture management capacity, were determined for the system of layers and the compound single layers. The transfer properties of the single layers were presented as a function of their thickness, mass per unit area, and areal porosity. The transfer properties of the system of layers were presented as a function of the thickness, mass per unit area, and bulk density of the systems. Regression analysis was applied to derive regression equations. The results obtained allowed assessment of the existence and trend of the influence, as well as evaluation of the strength of the dependences.

Selection of Clothing for a Cold Environment by Predicting Thermophysiological Comfort Limits

Results are presented from a study on the prediction of the insulation abilities of outerwear clothing for cold protection from the point of view of the thermophysiological comfort of the wearer. The Required Clothing Insulation (IREQ) index is used to simulate the abilities of 14 assemblies of layers designed for the production of winter jackets to protect the body in different cold environments. The calculations allow to assess the limits of applicability of the garments in terms of the thermophysiological comfort assured, the activities performed and the weather conditions. Discussions are presented on the correspondence between ISO11079:2007 and the online JavaScript code for calculation of IREQ based on it. The results predicted and their analysis have a practical use, as they allow to estimate the cold protection effectiveness of the textile layers used in an assembly at the design stage, thus giving room for necessary changes depending on the conditions of its use.