Hugh Gong

Twisting Mechanisms of Open-End Rotor Spun Hybrid Yarns:

We have developed a mechanical hybrid yam spinning system that produces different kinds of yam on a modified open-end rotor spinning frame. In order to understand the characteristics of hybrid yam and produce novel yarns, it is necessary to investigate yarn formation and the twisting mechanism in the spinning rotor during yam production. Our results reveal that the rotor revolution generally results in combining the filament yam and the staple fiber strand. The fiber twist angle of the strand in a hybrid yarn is smaller than that of a rotor spun single yam with the same spinning conditions. Although a fed filament yam has a false twist inserted by increasing the filament over-feed, the filament yarn in the hybrid yarn has a smaller level of fiber twist angle in the same direction as the twist of the staple fiber strand due to untwisting of the false twist.

Yarn geometry in woven fabrics

Geometrical models of textile structures are important to the design, manufacture and performance prediction of textile related products. The models existing in the textile literature do not take into account the variable deformation of the yarn cross-section along the yarn path and this seriously limits the accuracy of these models. The main aim of our study was to investigate how the yarn cross-section shape changes along the yarn path in the woven fabrics and how these changes relate to the yarn and fabric parameters such as yarn linear density, twist factor, warp and weft cover factors. Based on the elliptical cross-section model, models that describe how major and minor radii were affected by the control factors were developed.

Effect of wool surface modification on fluorocarbon chain re-orientation

There is an increasing demand for air-dry performance of fluorocarbon finished materials. Thus, surface modifications of wool fabrics were evaluated. Untreated, gaseous fluorinated, Chlorine/Hercosett processed 100 % wool fabrics were treated with different fluorochemicals and their liquid repellency after washing, and dry cleaning were evaluated. The results indicated that Chlorine-Hercosett treated samples, wool with a positive charge, after few washing cycles, showed better air dry performance with higher level of repellent properties. In addition, the comparison of the wool surface modifications treatment with different applied fluorochemicals, with different commercial formulations, illustrated that the fluorocarbon chain re-orientation and fastness properties are more affected by the nature of the wool surface while the used fluorocarbons showed more or less similar behaviours. In general, the fluorination increases fabric stiffness with lower fabric formability. The surface interface was effectively probed by X-ray Photoelectron Spectroscopy, XPS, which enabled the characterisation of the loss of surface lipids, the nature of the fibre oxidation and the deposition of fluoropolymers.

Modelling of Yarn Flattening in Woven Fabrics

The main aim of the study is to investigate how the yarn cross-section changes along the yarn path in woven fabrics and how these changes relate to the yarn and fabric parameters such as yarn linear density, twist factor, warp and weft cover factors. Based on the elliptical cross-section model, yarn flattening coefficients were calculated along the yarn path. A general equation of change in yarn flattening coefficient was developed in the form of e = a1 + a 2cosN(x) and the equation coefficients were analysed to find out the effects of the control factors. Twist factor was found to be the primary factor that had effects on a1 and a2, whereas the yarn linear density caused the highest change in N value.

Effects of finishing on the mechanical and thermal properties of fabrics from wool and hollow polyester fibres

The effects of finishing steps on hollow and solid polyester/wool have been studied in order to establish the processing behaviour and performance characteristics of fabrics from these fibres. The effect of hollow fibres on fabric tensile strength, pilling, and crease recovery were studied. In addition, the water vapour permeability, air permeability, thermal properties and fabric handle were investigated. The results show that finishing has no adverse effects on fabric strength. By using hollow fibres in the fabrics, the extent of pilling was reduced. Among the different steps of finishing, scouring has the most significant effect on fabric hand due mainly to the large reduction in both bending, and shear rigidity and hysteresis. The results on crease recovery, water vapour permeability and air permeability revealed that the fabric properties are more affected by the fabric structure than the type of polyester fibre. In addition, while the hollow fibre fabrics always have lower thermal conductivity than similar fabrics with solid polyester fibres, their thermal properties are greatly affected by the dyeing process.

Combination effects of open-end rotor spun hybrid yarns

We have developed a mechanical hybrid yarn spinning system that produces different yam types on a modified open-end rotor spinning frame. In order to improve yam properties and produce novel yams, we investigate the effects of combinations with typical hybrid yams by inserting two filament yarns with varying filament over-feeds. The results are a new rotor spun loop (RSL) yam made by combining two aspects of typical hybrid yarn production into one process, and an RSL yam where a filament yam, fed with a core filament over-feed (CFOF), is located in the center of one yarn and the other filament yam, fed with the effect filament over-feed (EFOF), makes a loop on the yarn surface. The stable conditions of RSL yam production are within a range of EFOF ≧ 4 (m/min) and -6.0 << CFOF << -4.0 (m/min).

Capillary flow of liquid water through yarns: a theoretical model

In extreme weather conditions and activity levels of human subjects, evaporation of sweat is critical for maintaining the sensorial and thermal comfort. Fabrics, from which clothes worn next to the skin are made, play an important role in facilitating the transfer of body liquid perspiration away from the skin to the environment through the mechanisms of capillary flow and evaporation. This work is a theoretical and experimental investigation of water flow characteristics of yarns with relevance to their structure geometry and constituent fiber chemistry. A theoretical model to predict the capillary flow of liquid water through yarns was proposed. The model is based on the Kozeny–Carman equation, which represents interfiber pores in terms of the hydraulic radius theory. Cotton, polyester and cotton/polyester yarns were produced by systematically varying different production parameters, including fiber type, yarn twist, yarn linear density and blend ratio. Plain knitted fabrics were produced and yarns taken from the produced fabrics were tested for horizontal linear flow of liquid water. The experimental results showed a strong correlation with the estimated results based on the theoretical model. The model predicts that as the ratio of interfiber pore space area to the total fiber perimeter within yarn increases, the flow rate is expected to increase.

The influence of component stiffness on the structure of multi-thread fancy bouclé yarn

This study examines the relationships between the structure of fancy bouclé yarns and the bending stiffness of the input threads that are used to make those fancy yarns. Four fancy bouclé yarns and an extra two confirmation bouclé yarns were made to test the impact of the bending stiffness of the effect input threads. Six fancy yarns were made to test the impact of bending stiffness of the core thread on the fancy yarn structure. The structure of the fancy yarn was defined by the number of fancy profiles, the size of fancy profile, the circularity ratio of fancy profile and the shape factor of fancy yarn. It was found that increasing the value of the stiffness of the effect thread increased the size of fancy profile but decreased both the number of fancy profiles and the shape factor of fancy yarn. Those relationships were represented by regression models that were significant at α = 0.10. The deviation between the theoretical values and the real values was −14.39% and 2.07%. Further, up to a value of 8.636 g mm2, the bending stiffness of the core thread appeared not to have an effect on the structure of the fancy yarns. This study is important as it is the first that accounts statistically for the impact of bending stiffness of the input threads on the structure of the resultant fancy yarns. Therefore, it aids fancy yarn manufacturers when designing fancy yarns with predicted structures.

Recognition of sketching from surface electromyography

The main objective of this study is to recognize sketching precisely and effectively in human–computer interaction. A surface electromyography (sEMG)-based sketching recognition method is proposed. We conducted an experiment in which we recorded the sEMG signals from the forearm muscles of two participants who were instructed to sketch seven basic one-stroke shapes. Subsequently, seven features of the sEMG time domain were extracted. After reducing data dimensionality using principal component analysis, these features were used as input vectors to a sketching recognition model based on support vector machines (SVMs). The performance of this model was compared to two other recognition models based on multilayer perceptron (MLP) neural networks and self-organization feature map (SOFM) neural networks. The average recognition rates for the seven basic one-stroke shapes of two participants achieved by the SVM-based and MLP-based models were both 98.5% in the test set, which were slightly superior to the performance of the SOFM classifier. Our results demonstrate the feasibility of converting forearm sEMG signals into sketching patterns.

A New Integrated Grey Water Footprint Assessment Method

Water footprint is a volumetric indicator of freshwater appropriation. The grey water footprint (GWF) provides a tool to assess the water volume needed to assimilate a pollutant. However, evaluating the impact on water environment cannot rely solely on volumetric consumption of freshwater. It demands accurate assessment criteria to reflect its environmental and ecological effects on ambient water resource. In this paper, a new assessment method is proposed: the effluent toxicity and the Potential Eco-toxic Effects Probe (PEEP) index of aquatic environment are taken into consideration. This method provides a comprehensive indicator for evaluating water footprint, specified in effluents’ ecological impact on ambient water sources.