Models for basic warp knitted fabrics Part II: single guide bar fabrics (closed-lap and open-lap)

2018 ◽  
Vol 89 (10) ◽  
pp. 1886-1916 ◽  
Author(s):  
Arif Kurbak
Keyword(s):  
Two Dimensions ◽  
Present Series ◽  
Plane Model ◽  
Knitted Fabrics ◽  
Real Samples ◽  
Cubic Curves ◽  
Technical Textiles ◽  
Medical Textiles ◽  
Special Cases

Warp knitted fabrics are mainly used as household goods, technical textiles, medical textiles, etc. Modeling of these fabrics is necessary for predicting the desired technical or medical functions beforehand. In this context, the present series of papers is devoted to the modeling of basic warp knitted fabrics. In this, Part II of this series, models for single guide bar fabrics are created. There are mainly two types of single bar fabrics, namely closed-lap and open-lap single bar fabrics. Structures are also changed by having different lapping movements up to the five needle spaces. In this work, 1 and 1, 2 and 1, 3 and 1, 4 and 1 closed-lap and 1 and 1, 2 and 1, 3 and 1 open-lap single bar warp knitted fabrics are considered. During modeling, the loop leanings in the course-wise direction are considered, curvature equalities at the loop parts are attained as much as possible, two connected parabolas are taken as the fabric plane model of the loop connection part, loop heads are taken as parametric ellipses in two dimensions and the remaining loop parts are modeled by wrapping parabolic or cubic curves on imaginary cylindrical or conical objects. The models created are versatile and they can be changed and used for special cases. The models created are drawn to scale by using the 3DS-MAX computer graphical program. At first glance, it is seen that the shapes obtained by the models are similar to the ones that can be observed in real samples.

scholarly journals Edge detection with trigonometric polynomial shearlets

2021 ◽  
Vol 47 (1) ◽  
Author(s):  
Kevin Schober ◽  
Jürgen Prestin ◽  
Serhii A. Stasyuk
Keyword(s):  
Edge Detection ◽  
Trigonometric Polynomial ◽  
Two Dimensions ◽  
Characteristic Functions ◽  
Numerical Examples ◽  
Special Cases ◽  
Periodic Characteristic ◽  
Boundary Curves ◽  
Theoretical Results ◽  
De La Vallée Poussin

AbstractIn this paper, we show that certain trigonometric polynomial shearlets which are special cases of directional de la Vallée Poussin-type wavelets are able to detect step discontinuities along boundary curves of periodic characteristic functions. Motivated by recent results for discrete shearlets in two dimensions, we provide lower and upper estimates for the magnitude of the corresponding inner products. In the proof, we use localization properties of trigonometric polynomial shearlets in the time and frequency domain and, among other things, bounds for certain Fresnel integrals. Moreover, we give numerical examples which underline the theoretical results.

scholarly journals Knitted Meshes for Reinforcing Building Composites

2019 ◽  
Vol 27 (4(136)) ◽  
pp. 102-111
Author(s):  
Zbigniew Mikołajczyk ◽  
Katarzyna Pieklak ◽  
Aleksandra Roszak
Keyword(s):  
Concrete Beam ◽  
Bending Strength ◽  
Relative Elongation ◽  
Testing Machine ◽  
Strength Analysis ◽  
Knitted Fabrics ◽  
Three Point Bending ◽  
Concrete Mass ◽  
Frp Composites ◽  
Technical Textiles

Modern technical textiles, including knitted fabrics, are widely used in the construction industry. Regarding textiles in concrete reinforcement, methods based on shredded fibres, meshes, reinforcing mats, woven textiles and knitted DOStapes are frequently used as underlays of concrete constructions. Textiles are also used in the reinforcement of fibrous FRP composites. The research presented focused on producing composites made of MapeiMapefill concrete mass with reinforcement in the form of three variants of knitted meshes made of 228 tex polyamide threads, polypropylene threads of 6.3 tex and 203 tex glass threads, as well as identification of their mechanical properties. The mesh variant made of glass fibre is especially noteworthy, as its strength is more than three times higher than that of polyamide meshes. At the same time, a very small relative elongation of 3% is observed for this variant of knitted fabric, which is a desired property regarding the comparatively low stretching extension of concrete. In the process of making the composites, the adhesion of the concrete mass to the surface of the threads was analyzed. For this purpose, a "Sopro HE449" type agent was used. Composite beams were subjected to a three-point bending strength analysis on a testing machine. The results of strength measurements of the composites obtained prove that those with glass fibres demonstrate a threefold increase in strength compared to the original concrete beam.

scholarly journals Characterization of functional single jersey knitted fabrics using non-conventional yarns for sportswear

2016 ◽  
Vol 88 (3) ◽  
pp. 275-292 ◽  
Author(s):  
Jefferson M Souza ◽  
Sandra Sampaio ◽  
Welter C Silva ◽  
Sidney G de Lima ◽  
Andrea Zille ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Water Vapor Permeability ◽  
Thermal Control ◽  
Vapor Permeability ◽  
Knitted Fabrics ◽  
Moisture Management ◽  
Antimicrobial Efficiency ◽  
Technical Textiles ◽  
Single Jersey

Eight functional single jersey plain knitted fabrics have been developed in order to assess a quantitative analysis of various comfort-related properties in terms of thermal control, air and water vapor permeability, wickability, coefficient of kinetic friction and antimicrobial efficiency, using eight different commercially available functional yarns: Polyester Craque® and viscose Craque® conventional yarns as controls; Finecool® and Coolmax® polyester yarns for moisture management and quick drying; Holofiber® polyester yarns containing an optical responsive material that the producer claims to improve body oxygenation; Airclo® polyester hollow yarns for efficient control of body temperature; and, finally, polyester Trevira® and viscose Seacell® for antimicrobial activity. According to the results, Coolmax® for moisture management, Airclo® for thermal control and Seacell® for antimicrobial activity present the best performances as technical textiles for sportswear for the respective specific functional property.

scholarly journals Quadratic algebra contractions and second-order superintegrable systems

2014 ◽  
Vol 12 (05) ◽  
pp. 583-612 ◽  
Author(s):  
Ernest G. Kalnins ◽  
W. Miller
Keyword(s):  
Constant Curvature ◽  
Two Dimensions ◽  
Second Order ◽  
Quadratic Algebra ◽  
Quadratic Algebras ◽  
Physical Systems ◽  
Special Cases ◽  
Superintegrable Systems ◽  
Wilson Polynomials ◽  
Symmetry Algebras

Quadratic algebras are generalizations of Lie algebras; they include the symmetry algebras of second-order superintegrable systems in two dimensions as special cases. The superintegrable systems are exactly solvable physical systems in classical and quantum mechanics. For constant curvature spaces, we show that the free quadratic algebras generated by the first- and second-order elements in the enveloping algebras of their Euclidean and orthogonal symmetry algebras correspond one-to-one with the possible superintegrable systems with potential defined on these spaces. We describe a contraction theory for quadratic algebras and show that for constant curvature superintegrable systems, ordinary Lie algebra contractions induce contractions of the quadratic algebras of the superintegrable systems that correspond to geometrical pointwise limits of the physical systems. One consequence is that by contracting function space realizations of representations of the generic superintegrable quantum system on the 2-sphere (which give the structure equations for Racah/Wilson polynomials) to the other superintegrable systems one obtains the full Askey scheme of orthogonal hypergeometric polynomials.

scholarly journals Yarn Damage Evaluation in the Flat Knitting Process

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Waqar Iqbal ◽  
Yaming Jiang ◽  
Ye-xiong Qi ◽  
Lei Xu
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Raw Materials ◽  
Frictional Coefficient ◽  
Microscopic Analysis ◽  
Significant Loss ◽  
Cross Sectional ◽  
Knitted Fabrics ◽  
Technical Textiles ◽  
Yarn Properties

AbstractTextile yarns are subjected to numerous types of forces during knitting, usually leading to yarn damages, such as decrease in tensile, bending, shearing, and surface properties, which are closely related to different yarn properties, knitted structures/actions, and machine settings. This article comprehensively evaluated yarn damages in the computerized flat knitting process. Five different commercially available and commonly used yarns including cotton, wool, polyester, acrylic, and viscose were selected as raw materials, and the tensile, bending, shear, and frictional properties were investigated and compared before knitting and after being unraveled from plain- and rib-knitted fabrics, respectively. The results show that knitting actions/structures exhibit different damage extents for all different raw materials. It has been observed that the modulus is declined by 3–30% for bending, 2–10% for tensile, and 8–80% for shearing due to flat knitting action, respectively. The frictional coefficient of yarns also increased from 6 to 23%. As compared to yarn before knitting, the yarns unroved from plain and rib structures have been damaged to a great extent as a result of the loss of mechanical properties. The results are completely in agreement with the statistical analysis that clearly represents the significant loss in yarn properties during the knitting process. The microscopic analysis of the yarns clearly illustrates the effect of knitting action on yarn surface and mechanical properties. For yarn’s cross-sectional shearing properties testing, this article self-designed an innovative “Yarn Shear Testing Device.” The methodology and results are of great importance for improving the quality of knitted products, evaluating knitting yarns’ knittability, and in the development of high-performance technical textiles.

scholarly journals The Flow of Ice, Treated as a Newtonian Viscous Liquid, around a Cylindrical Obstacle Near the Bed of a Glacier

1979 ◽  
Vol 23 (89) ◽  
pp. 117-129 ◽  
Author(s):  
E. M. Morris
Keyword(s):  
Boundary Conditions ◽  
Viscous Liquid ◽  
Equations Of Motion ◽  
Two Dimensions ◽  
Plane Boundary ◽  
Solid Inclusion ◽  
Special Cases ◽  
Cylindrical Solid ◽  
Rock Bed ◽  
Glacier Ice

AbstractThis paper describes an analytical solution of the equations of motion and heat conduction for ice flowing around a cylindrical solid inclusion and over a solid plane boundary. This is intended to be a simplified representation of the flow of clean glacier ice around a stone and over a rigid rock bed. The ice is treated as a Newtonian viscous liquid and the equations are solved in two dimensions. Regelation boundary conditions are applied at both ice–rock interfaces. It is found that finite solutions for the temperature and stream function only exist for the special cases in which two dimensionless critical wavelengths are zero. That is, unless the stone is very far from the glacial bed, the classical regelation boundary conditions cannot be obeyed over the whole of its surface.

Softening Instability: Part II—Localization Into Ellipsoidal Regions

1988 ◽  
Vol 55 (3) ◽  
pp. 523-529 ◽  
Author(s):  
Zdeneˇk P. Bazˇant
Keyword(s):  
Strain Softening ◽  
Finite Size ◽  
Elastic Solid ◽  
Two Dimensions ◽  
The Body ◽  
Three Dimensions ◽  
Strain Diagram ◽  
Equilibrium Path ◽  
Special Cases ◽  
Localization Instability

Extending the preceding study of exact solutions for finite-size strain-softening regions in layers and infinite space, exact solution of localization instability is obtained for the localization of strain into an ellipsoidal region in an infinite solid. The solution exploits Eshelby’s theorem for eigenstrains in elliptical inclusions in an infinite elastic solid. The special cases of localization of strain into a spherical region in three dimensions and into a circular region in two dimensions are further solved for finite solids — spheres in 3D and circles in 2D. The solutions show that even if the body is infinite the localization into finite regions of such shapes cannot take place at the start of strain-softening (a state corresponding to the peak of the stress-strain diagram) but at a finite strain-softening slope. If the size of the body relative to the size of the softening region is decreased and the boundary is restrained, homogeneous strain-softening remains stable into a larger strain. The results also can be used as checks for finite element programs for strain-softening. The present solutions determine only stability of equilibration states but not bifurcations of the equilibrium path.

scholarly journals Rational Cubics and Conics Representation: A Practical Approach

1970 ◽  
Vol 1 (2) ◽  
Author(s):  
M. Sarfraz ◽  
Z. Habib
Keyword(s):  
Computer Graphics ◽  
Cubic Spline ◽  
Practical Approach ◽  
Shape Parameters ◽  
Conic Sections ◽  
Interpolation Spline ◽  
Cubic Curves ◽  
Spline Curve ◽  
Special Cases

A rational cubic spline, with one family of shape parameters, has been discussed with the view to its application in Computer Graphics. It incorporates both conic sections and parametric cubic curves as special cases. The parameters (weights), in the description of the spline curve can be used to modify the shape of the curve, locally and globally, at the knot intervals. The rational cubic spline attains parametric   smoothness whereas the stitching of the conic segments preserves visually reasonable smoothness at the neighboring knots. The curve scheme is interpolatory and can plot parabolic, hyperbolic, elliptic, and circular splines independently as well as bits and pieces of a rational cubic spline.Key Words: Computer Graphics, Interpolation, Spline, Conic, Rational Cubic

scholarly journals Application of Knitting Structure Textiles in Medical Areas

2018 ◽  
Vol 18 (2) ◽  
pp. 181-191 ◽  
Author(s):  
Xiaohui Zhang ◽  
Pibo Ma
Keyword(s):  
Present Article ◽  
High Tech ◽  
Flexible Structure ◽  
Knitted Fabrics ◽  
Artificial Blood ◽  
Forming Technology ◽  
Medical Textiles ◽  
Artificial Blood Vessels ◽  
Expandable Metallic Stents ◽  
Support Devices

Abstract There are many kinds of medical textiles, such as woven textiles, non-woven textiles, braided textiles and knitted textiles. Non-woven medical textiles constitute more than 60% of the total medical textiles used, but are almost disposable ordinary medical textiles. While knitted fabrics forms a small part of the medical textiles, but are greatly applied in high-tech medical textiles, containing artificial blood vessels, hernia patches, cardiac support devices, knitted medical expandable metallic stents and tendon scaffolds. Knitting structures, including weft knitting structure and warp knitting structure. The knitted textiles are popular for their loose structure, greater flexibility, higher porosity, more flexible structure and better forming technology. The present article will introduce some knitting structures and materials applied in the medical textiles in accordance with non-implantable, implantable, extra-corporeal textiles and healthcare and hygiene products.

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