Abrasion evaluation of spliced and parent yarns with a new simulator abrader tester

In order to evaluate the abrasion effect on both spliced and parent yarn performances, a newly developed abrader tester simulating the real cumulative weaving stresses is used. Three weaving parameters: loom speed, splice positions during weaving and yarn tension are tested to simulate the mechanical behaviour of spliced and parent thread yarns. The results show that the spliced yarn’s abrasion resistance, expressed by lifetime cycle numbers, is more affected by the weaving parameters used in our developed abrader simulator tester than by others. In this work, the results obtained by our simulator abrader tester and the cyclical tensioning ones are compared to regression analysis models. According to the highest coefficients of determination ranging from 0.955 to 0.999, it is found that a good prediction of spliced and parent yarn breakages is possible. Comparing two interesting splice positions on the loom: the splice beat-up position and the splice shedding one, we conclude that the splice shedding position increases breakage rate.     

Optimization of textile parameters of plain woven vascular prostheses

This paper investigates and reports the effect of some textile parameters (yarn and fabric parameters) on the main performances of plain woven vascular prostheses in order to enhance their overall quality. We weaved tubular structures with different fabric densities using texturized Dacron® polyester filament yarns with different linear densities and filament counts, in warp and weft directions. The performances of the manufactured samples, such as wall porosity, water permeability and mechanical features, have been tested. By adopting a two‐level fractional factorial design of experiments, the responses were fitted to predictive models using a multiple linear regression method. The models were tested by variance analysis and validated by correlation between measured and predicted values. We determined the optimum settings of main textile parameters enhancing plain woven vascular prosthesis quality by contour plots method.     

Fabric wrinkling evaluation: a method developed using digital image analysis

The textile and clothing industry has conventionally used subjective methods for the assessment of fabric wrinkling. Indeed, the fabrics were usually evaluated subjectively in reference to a set of visual standards. However, the visual assessments of the wrinkling degree, often showing inconsistencies between wrinkle judgments of observers, are severely influenced by the color and the fabric texture which may exist. In this paper, an objective method which permits an evaluation of multidirectional wrinkling of any colored fabric has been developed using digital image analysis. This method consists in capturing images of the color wrinkled fabrics and processing them in simple steps using image‐processing software. The surface roughness, density, width, length, number, and height of the wrinkles, considered as wrinkling characteristics, were extracted. Wrinkle degree was selected to use as the comparative parameter of the result evaluation from conventional and digital methods. The wrinkle grade of each fabric sample obtained through the conventional technique was statistically compared with that obtained through the digital technique developed. This study demonstrates that the results of the digital method developed for wrinkle evaluation of colored fabrics were similar to those of conventional methods of wrinkling evaluation.     

Influence of grafting with acrylic acid on the dyeing properties of polyamide 6.6 fibres

Polyamide 6.6 fibres were modified for the improvement of dyeing affinity using a graft copolymerisation method. These fibres were grafted with acrylic acid as monomer. The influence of the chemical modification of polyamide 6.6 fibres on the dyeing properties was investigated using a cationic dye (Red Astrazon 5BL). It was shown that the dye uptake of the modified fibres was greater than that of the unmodified fibres. The kinetic study of the cationic dye used at various grafting percentages showed an improvement of the dye build‐up rate, such as its exhaustion. In addition, an increase in the adsorption of the dye quantity fixed on the surface layer of the fibre made up of the grafted molecules was announced. Colour fastness to washing was improved with the grafting percentage. The modelling of the adsorption isotherms using Langmuir, Freundlich and Jossen relations allows the determination of isotherm constants. The results obtained from this modelling study show the existence of several models corresponding to various percentages of grafting.     

Qualitative evaluation of the germination frequency in Zr–Fe binary alloy

Major thermo-physical properties data are of fundamental importance to accurate and reliable design of melting and casting processes. In this paper, we show that we can control the germination process using thermodynamics data. These data must be known for the entire period of time and temperature range of interest in any given condition. In addition, a kinetic approach is employed to predict the microstructure of alloys. Viscosity data for Zr₇₆Fe₂₄, are fitted with an empirical relation. The best fit allows to estimate, through the resistance to germination factor, thermodynamic proprieties of interest (i.e., namely the enthalpy of fusion, the surface tension, the molar volume and the glass temperature). From the values of these quantities, the parameters (T, t) can be estimated. The temperature T is found between 930 K and 1194 K and the time t can be derived from the plateau of the germination frequency–temperature profile.     

Occurrence of deoxynivalenol in durum wheat in Tunisia

Wheat is frequently contaminated by the deoxynivalenol (DON) which is a member of the trichotecene family, the most important group of mycotoxins produced by the Fusarium moulds. As Tunisian population is a big consumer of cereals mainly durum wheat, human exposure to DON can be, consequently high. This survey was performed to study the occurrence of DON in Tunisian durum wheat area during the crop of 2007. A total of 65 samples of durum wheat from five cultivating locations in the North of Tunisia, the major cropping area, were analysed. To detect and to quantify the mycotoxin DON, an efficient HPLC/UV method was developed, including immunoaffinity step for DON extraction from durum wheat followed by liquid chromatography (LC) for quantification. As DON is a water soluble toxin, the extraction procedure from wheat samples was performed using water. Samples were centrifuged then passed through the immunoaffinity columns. After column’s washing, the toxin was slowly eluted by methanol. Wheat sample extracts were injected to the LC system set at a wavelength of 220 nm. From 65 samples, 83% showed DON contamination with averages ranging from 12.8 ± 5% to 30.5 ± 13.3% μg/g exceeding the maximum permitted limit of 1.75 μg/g set by the European Commission in wheat.     

Consistency problems in ER-schemas for database systems

At a conceptual level data modelling consists in providing a structured form of relevant information and to accompany structures with constraints in order to capture more semantics. Cardinality constraints are among the most popular classes of constraints in database models. While each constraint class is now well understood, little is done about their interaction since possible conflicts among them may appear. The global coherence of these constraints must be considered before creating the physical corresponding database. In order to help in database design, our aim is then to propose a tool for reasoning about a set of Cardinality constraints. We will treat the global coherence using mathematical programming technique. The analyses and the detection of invalid sub-schemas will be done using Fourier-Motzkin elimination.     

Adaptive call admission control in 3GPP LTE networks

In this article, we propose new methods to reduce the handoff blocking probability in the 3rd Generation Partnership Project Long Term Evolution wireless networks. This reduction is based on an adaptive call admission control scheme that provides QoS guarantees and gives the priority of handoff call over new call in admission. The performance results of the proposed schemes are compared with other competing methods using simulation analysis. Simulation results show the major impact on the performance of the 3rd Generation Partnership Project Long Term Evolution network, which is reflected in increased resource utilization ratio to (99%) and in the ability in satisfying the requirements of QoS in terms of call blocking probability (less than 0.0628 for Voice over IP service) and dropping probability rate (less than 0.0558).Copyright © 2012 John Wiley & Sons, Ltd.