999 resultados para Yarn quality


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To improve yarn quality in ring spinning frame, this paper examines transposal spinning with the movable balloon control ring. The left-transposal spinning and the right-transposal spinning were experimented to spin two yarns; after installing the movable balloon control ring, the two methods were respectively used to spin two other yarns again. All the experiments were on the same ring frame and the raw material was wool/polyester blend roving with a ration of 30/70. The main quality indexes of the four yarns were tested and analyzed, including hairiness, tensile property, evenness and usual faults. The results show that the yarn spun by the left-transposal spinning has a better quality than the right-transposal spinning, and after adding the movable balloon control ring, the improvement of yarn hairiness strength and evenness, as well usual faults, is very obvious. So, in the advantage of transposal spinning, the method of installing the movable balloon control ring can improve some deteriorative problems and make yarn quality better. In addition, the method gives new insight into energy efficiency. The research in this field in on the way and the result is in accord with the Low-carbon Economy.

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A novel method of improving yarn quality by improved incorporation of fibres into the yarn structure has been proposed and investigated. This methid enables spinning of finer, stronger, low twist, less hairy and more abarsion resistant yarns.

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Cover title.

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Bibliography: p. 17-18.

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This paper reports the effects of bleaching of alpaca tops and dyeing of bleached alpaca tops/yarns on the quality of tops and yarns. A dark brown alpaca top was bleached with hydrogen peroxide. Two bleaching methods were tried for effectiveness of color removal. A portion of each bleached top was dyed after bleaching. Color parameters were examined for unbleached, bleached and bleached/dyed tops, these tops were then converted into yarns of different twist levels and counts using a worsted spinning system. Some of the bleached yarn from each bleaching method was dyed in a package dye vat to compare the difference of top dyeing versus yarn package dyeing on yarn quality. Fiber diameter, yarn strength, yarn evenness, yarn hairiness and fiber degradation were tested to examine the effects of bleaching and dyeing on these properties at top and yarn stages. A processing route for bleaching and dyeing alpaca fiber was recommended.

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Different spinning mills use different raw materials, processing methodologies, and equipment, all of which influence the quality of the yarns produced. Because of many variables, there is a difficulty in developing a universal empirical/theoretical model. This work presents a multilayer perceptron algorithm (MLP) model for the purpose of building a mill specific worsted spinning performance prediction tool. Sixteen inputs are used to predict key yarn properties and spinning performance, including number of fibers in cross-section, unevenness (U%), thin places, neps, yarn tenacity, elongation at break, thick places, and spinning ends-down. Validation of the model on mill specific commercial data set shows that the general fit to the target values is good. Importantly, the performance of the MLP shows a certain degree of stability to different, random selections of independent test data. Subsequent comparison against the predicted outputs of Sirolan Yarnspec™ confirms the overall performance of the artificial neural network (ANN) method to be more accuratefor mill specific predictions.

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For a given fiber spun to pre-determined yarn specifications, the spinning performance of the yarn usually varies from mill to mill. For this reason, it is necessary to develop an empirical model that can encompass all known processing variables that exist in different spinning mills, and then generalize this information and be able to accurately predict yarn quality for an individual mill. This paper reports a method for predicting worsted spinning performance with an artificial neural network (ANN) trained with backpropagation. The applicability of artificial neural networks for predicting spinning performance is first evaluated against a well established prediction and benchmarking tool (Sirolan YarnspecTM). The ANN is then subsequently trained with commercial mill data to assess the feasibility of the method as a mill-specific performance prediction tool. Incorporating mill-specific data results in an improved fit to the commercial mill data set, suggesting that the proposed method has the ability to predict the spinning performance of a specific mill accurately.

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A novel spinning method: embeddable and locatable spinning, is reported for the first time in this paper. Analysis of the key restrictions of the conventional and some novel ring-spinning were studied; evolvement and principles of embeddable and locatable spinning were then introduced. Analysis indicated that embeddable and locatable spinning could overcome the existing restrictions of ring spinning and improve the spinning performance of fiber strands as well as the quality of the resulting yarn. Super-fine and colorful figured yarns could be produced successfully, and most fibers shorter than can be spun in traditional spinning could be well embedded into a yarn by embeddable and locatable spinning method; even staple fibers of low qualities could be used to produce a fine yarn of high qualities in the novel spinning system. This novel spinning method shows huge application potentials in textile industry by improving the yarn quality, developing super-fine yarn, and increasing fiber utilization rate.

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This work evaluated the following aspects of the use of exclusion netting in low chill stone fruit: the efficacy of protection from fruit fly for this highly susceptible crop; the effects on environmental factors; and the effects on crop development. Concurrently, an economic viability study on the use of exclusion netting was undertaken. The trial site was a 0.6-ha block of low chill stone fruit at Nambour, south-east Queensland, Australia. In this area, populations of Queensland fruit fly (Bactrocera tryoni) are known to be substantial, particularly in spring and summer. The trial block contained healthy 4-year-old trees as follows: 96 peach trees (Prunus persica cv. Flordaprince) and 80 nectarine trees (40 P. persica var. nucipersica cv. White Satin and 40 P. persica var. nucipersica cv. Sunwright). Exclusion netting was installed over approximately half of the block in february 2001. The net was a UV-stabilized structural knitted fabric made from high-density polyethylene yarn with a 10-year prorated UV degradation warranty. The results demonstrated the efficacy of exclusion netting in the control of fruit flies. Exclusion netting increased maximum temperatures by 4.4 deg C and decreased minimum temperatures by 0.5 deg C. Although exclusion netting reduced irradiance by approximately 20%, it enhanced fruit development by 7-10 days and improved fruit quality by increasing sugar concentration by 20-30% and colour intensity by 20%.

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The goal of this study was to characterize the image quality of our dedicated, quasi-monochromatic spectrum, cone beam breast imaging system under scatter corrected and non-scatter corrected conditions for a variety of breast compositions. CT projections were acquired of a breast phantom containing two concentric sets of acrylic spheres that varied in size (1-8mm) based on their polar position. The breast phantom was filled with 3 different concentrations of methanol and water, simulating a range of breast densities (0.79-1.0g/cc); acrylic yarn was sometimes included to simulate connective tissue of a breast. For each phantom condition, 2D scatter was measured for all projection angles. Scatter-corrected and uncorrected projections were then reconstructed with an iterative ordered subsets convex algorithm. Reconstructed image quality was characterized using SNR and contrast analysis, and followed by a human observer detection task for the spheres in the different concentric rings. Results show that scatter correction effectively reduces the cupping artifact and improves image contrast and SNR. Results from the observer study indicate that there was no statistical difference in the number or sizes of lesions observed in the scatter versus non-scatter corrected images for all densities. Nonetheless, applying scatter correction for differing breast conditions improves overall image quality.

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SolospunTM is a spinning technology which provides the means to produce a singles yarn that can be successfully woven as either warp or weft. The technology is a versatile and cost effective alternative to two-folding, Sirospun or sizing. It offers significant benefits in terms of efficiency and productivity. SolospunTM is a simple, inexpensive, clip-on attachment for the spinning of long staple, weavable singles yarns. The technology is the result of a joint development between CSIRO Textile and Fibre Technology, The Woolmark Company and WRONZ and was commercially released in 1998. It is now successfully operating in worsted mills worldwide. The SolospunTM hardware consists of a pair of rollers held in a bracket, which is clipped onto the front of the pendulum-drafting arm. Each roller is positioned immediately below, and parallel to, each top front draft roller where it interacts with the emerging drafted fibre strand before twist insertion. The roller-fibre interaction subtly changes the structure of the yarn, which dramatically increases its abrasion resistance. This allows Solospun yarns to be woven without twofolding or sizing, providing significant cost savings. Depending on fabric structure, weaving performance is equivalent to that of conventional two-fold yarns. Fabrics woven from SolospunTM yarns are of good quality and appearance. Some aspects, including preferred hand and FAST results, are equal or superior to two-fold yarn fabrics. As with compact and condensed spinning, SolospunTM offers significant reductions in yarn
hairiness. However, Solospun can be simply implemented on existing spinning frames and goes much further by making the singles yarns weavable.

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Yarn hairiness affects not only the quality of products, but also the productivity in spinning and weaving. Too much yarn hairiness is undesirable for many end uses as well as the spinning and post spinning processes. The main aims of this project are to examine the hairiness features of various yarns and to reduce yarn hairiness. The thesis covers five related areas – hairiness assessment, factors affecting yarn hairiness, the hairiness of newly developed yarns, yarn hairiness reduction, and effect of yarn hairiness on the energy consumption in ring spinning. The worsted cashmere, pure wool and wool/cashmere blend yarns were employed to investigate the effect of some fibre parameters on the yarn hairiness. A single exponential distribution of the hair-length was confirmed first, using the data from the Zweigle G565 Hairiness Meter. A linear relationship was observed between the blend ratio and the hairiness indexes. In particular, the effect of fibre crimp or curvature on yarn hairiness is examined. The theory of yarn hairiness composition was also developed further. The effect of draft ratio and spindle speed on the hairiness of worsted wool yarn was examined next with a factorial experiment design. Several new hairiness indexes, namely the relative hairiness indexes, have been used to explain the results obtained. In the investigation of the hairiness of newly developed yarns, the hairiness of the Compact Spun and Roller-Jet-Spun yarns was examined first. The composition of the yarn hairiness, the hair-length distribution, and the effect of test speed on yarn hairiness were then studied. An important finding is that for both yarns, the predominant hairiness feature is the looped hairs. A comparison of the hairiness of Solospun yarns and the equivalent ring spun wool yarns was undertaken. The hair-length distribution of the Solospun yarn was examined first. The Solospun yarns used had fewer hairs in most hair-length groups and lower variations in hairiness. In addition, the effect of twist level and spindle speed on the hairiness of Solospun and conventional ring spun yarns has also been discussed. A novel approach of reducing yarn hairiness – spinning with a ‘Diagonal’ yarn path was examined next. Both ‘Left Diagonal’ and ‘Right Diagonal’ yarn arrangements were studied. A new finding is that the ‘Right Diagonal’ yarn path leads to reduced hairiness for the Z-twist yarn, while yarn evenness and tenacity are not as sensitive to the modified yarn path. The mechanism of hairiness reduction with the ‘Diagonal’ yarn path has been discussed. The spinning performance of “Right Diagonal” yarn arrangement has also been evaluated. Finally, the effect of yarn hairiness on the energy consumption in ring spinning has been investigated theoretically and experimentally. A theoretical model has been developed, which represents the first attempt at theoretically investigating the influence of yarn hairiness on energy consumption during the winding stage of ring spinning. The experimental results have generally confirmed predictions of this model. Recommendations for further research in this area have also been made in the concluding chapter of this thesis.

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Hairiness is an important quality parameter of spun yarns. It not only affects the quality of yarns, but also the weaving and knitting performance of yarns as well as the quality of the resultant fabrics. Various developments regarding yarn hairiness have been reported in the last decade. These cover aspects such as hairiness measurement, modeling, simulation, spinning modifications and post spinning treatments to reduce hairiness. This study is an attempt to critically review all significant recent developments regarding yarn hairiness. Further possibilities of research and future work are also briefly discussed.