Neural network meta‐model of fibrous materials based on discrete‐event simulation. Part 1: discrete‐event simulation model of one‐dimensional fibrous material

We present a new approach to the simulation of one‐dimensional fibrous material irregularity. This approach is based on the idea of a random simulation step and the ability to trace each separate fiber or group of fibers during computer simulation. The simulation models developed are free of restrictions inherent in theoretical models and can simulate irregularity in a wide range of statistical distributions and simulation conditions. This paper presents the basic model of fibrous materials made from homogeneous separated fibers and its extension to blended fibrous materials, a model of thickness irregularity, and the extension of the basic model to a random group of fibers. The effects of the fiber length and fiber front ends were also simulated and analyzed.     

Discrete‐event simulation model of roll‐drafting process

This paper presents a model of the roll‐drafting process which is based on the concept of discrete‐event simulation (DES). This model is free of limitations and simplifications which are inherent in the known models of the roll‐drafting process and is able to trace each separated fiber within the roll‐drafting zone. Due to this feature DES model enables investigation of a wide range of roll‐drafting cases and representations. The influence of the parameters of the basic roll‐drafting model was studied. Models of the first and the second limit schemes, models with a randomly distributed velocity change point, and a model with a shifting velocity change point were elaborated and studied on the basis of the basic model of the roll‐drafting process. The effect of the feedback depth was simulated and analyzed in the frame of the model with the shifting velocity change point. The elaborated model and the obtained results will be useful for creating a neural network meta‐model of the roll‐drafting process.     

A non‐linear viscoelastic model for describing the fatigue behaviour of braided artificial ligaments

The objective of this paper is the determination of the dynamic fatigue behaviour of braided ligaments made of polypropylene by using a rheological model and an experimental fatigue tester. A non‐linear viscoelastic model has been proposed to describe the time‐dependent deformation behaviour of braided anterior cruciate ligament prosthesis. The elastic modulus and viscous modulus are calculated for different fatigue tests. The developed fatigue tester allows to combine simultaneous cyclic solicitations of bending and traction. These combined cyclic solicitations generate new mechanical properties of the prosthesis such as increasing of the dissipative factor, the material damping and the residual deformation with the number of fatigue cycles.     

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Eco‐friendly plasma treatment of linen‐containing fabrics

In the present work, linen‐containing fabrics were treated with atmospheric pressure plasmas of oxygen, air and nitrogen, and the impact of plasma treatment conditions on the surface chemistry and topography was evaluated. Plasma treatment is accompanied by a remarkable improvement in the hydrophilic properties: creation of new functional groups along with a noticeable increase in the affinity of treated substrates for subsequent H₂O₂‐bleaching. The extent of improvement in wettability as well as subsequent bleachability is governed by both the plasma gas, i.e. oxygen > air > nitrogen > none, and the discharge power, i.e. the higher the power supply, the shorter and greater was the modification extent. Oxygen or air plasma treatment significantly upgrades the hydrophilicity, enhances the subsequent bleachability, saves time, water and energy as well as prevents or decreases pollution at the source, i.e. an eco‐friendly substitute for conventional scouring of linen‐based textiles.     

Tensile characteristics of Dref‐III friction core‐spun yarns

The tensile characteristics of Dref‐III friction spun yarns with jute as core and cotton as sheath components have been studied. Three yarns with different core–sheath proportions such as 55/45, 65/35 and 75/25 jute/cotton friction spun yarns were produced by using the Dref‐III friction spinning system. The influence of core and sheath components on the tensile properties at three different traverse rates at 150 mm/min, 750 mm/min and 1500 mm/min, respectively, have been reported. The work of rupture and specific work of rupture at break of these yarns were also analysed. From the test results, the maximum work of rupture was found in 55/45 core–sheath (jute/cotton) friction spun yarn when compared to 65/35 and 75/25 core–sheath (jute/cotton) friction spun yarns. It is due to the higher core–sheath interaction factor (CSI_T = 26.14) and better yarn‐packing density because of higher proportion of cotton fibres in the sheath component. The breaking tenacity and contribution factor of core and sheath component (CSI_T) of jute/cotton friction spun yarns were also analysed using multivariable ANOVA analysis.     

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Hard‐to‐cook phenomenon in common beans — A review

Legumes are one of the world's most important sources of food supply, especially in developing countries, in terms of food energy as well as nutrients. Common beans are a good source of proteins, vitamins (thiamine, riboflavin, niacin, vitamin B₆) and certain minerals (Ca, Fe, Cu, Zn, P, K, and Mg). They are an excellent source of complex carbohydrates and polyunsaturated free fatty acids (linoleic, linolenic). However, common beans have several undesirable attributes, such as long cooking times, being enzyme inhibitors, phytates, flatus factors, and phenolic compounds, having a “beany” flavor, and being lectins and allergens, which should be removed or eliminated for effective utilization.

Grain quality of common beans is determined by factors such as acceptability by the consumer, soaking characteristics, cooking quality, and nutritive value. Acceptability characteristics include a wide variety of attributes, such as grain size, shape, color, appearance, stability under storage conditions, cooking properties, quality of the product obtained, and flavor.

Storage of common beans under adverse conditions of high temperature and high humidity renders them susceptible to a hardening phenomenon, also known as the hard‐to‐cook (HTC) defect. Beans with this defect are characterized by extended cooking times for cotyledon softening, are less acceptable to the consumer, and are of lower nutritive value. Mechanisms involved in the HTC defect have not been elucidated satisfactorily. Attempts to provide a definitive explanation of this phenomenon have not been successful. The most important hypotheses that have been proposed to explain the cause of bean hardening are (1) lipid oxidation and/or polymerization, (2) formation of insoluble pectates, (3) lignification of middle lamella, and (4) multiple mechanisms. Most researchers have reported that the defect develops in the cotyledons. Recently, some authors have suggested that the seed coat plays a significant role in the process of common bean hardening. A better knowledge of cotyledon and seed coat microstructure may lead to a better understanding of the causes of seed hardness.

In order to prevent the development of the HTC defect several procedures have been proposed: (1) appropriate storage, (2) controlled atmospheres, and (3) pretreatments. Probably, the most workable solution to the hardening phenomenon may be the development of materials less prone to HTC phenomenon.

Decreasing cooking time, increasing nutritive value, and improving sensory properties of seeds with HTC defect would have great nutritional and economical impact. Furthermore, an understanding of the mechanisms leading to reversibility of this phenomenon would provide insight into the development of the defect itself and would aid in the search for appropriate methods to prevent it.

Efforts to develop technological processes are needed in order to transform the HTC beans into edible and useful products. Several economic alternatives to utilize HTC common beans have been proposed: (1) dehulling, (2) extrusion, (3) solid state fermentation, (4) quick‐cooking beans, and (5) production of protein concentrates and isolates and starch fractions.     

The mechanics of buckling fiber in relation to fabric‐evoked prickliness: a theory model of single fiber prickling human skin

The simple Euler model of buckling of a slender rod has been commonly used to explain the mechanics in relation to the buckling of fabric‐evoked prickliness. Unfortunately, few works have paid attention to its applicability into the buckling behavior of fiber prickling human skin to evoke prickliness, though the friction between the fiber end and the skin and the firmness of a fiber end held in fabric (denoted as elastic stiffness) are considered to be among the main factors for fabric‐evoked prickliness. To model the mechanics of buckling of a fiber in relation to fabric‐evoked prickliness, the fiber–skin friction, the elastic stiffness, and the initial inclined angle of the fiber are introduced into the simple Euler model of buckling of a slender rod. Then, a sensitivity analysis is performed on these three factors to observe their role in the buckling behavior of a fiber. The results demonstrate that the fiber–skin friction and the elastic stiffness have a significant effect on the buckling behavior of fiber end prickling skin and the stimulus intensity to skin. Additionally, the fiber with an initial inclined angle can exert compression force on skin above the average force threshold of nociceptors responsible for fabric‐evoked prickliness, and the force size depends on the fiber property and its end‐restraint intensity. Therefore, it is not appropriate for the assumption of a fixed‐hinged boundary of the fiber end prickling human skin. In this sense, a developed fiber–skin coupling model provides a good modeling for the buckling behavior of fiber end pricking human skin.     

A cross‐cluster and cross‐region analysis of fashion brand extensions

To obtain sustainable growth in revenue and market share, many fashion brands deploy category extensions and line extensions. In this paper, we examine how different fashion brands in Europe, North America, and Asia execute their brand extension strategies over different periods. By classifying different fashion brands into four clusters according to different price points and fashion contents, we conduct a cross‐region and cross‐cluster analysis to examine how different fashion brands execute their brand extension strategies. Our analysis is based on publicly available data associated with 48 fashion brands over a 90‐year period. We discuss our findings along with managerial insights.     

我国地区乳品抗生素残留的meta分析

探讨了2000~2014年之间我国地区乳品中抗生素残留问题以及乳品中抗生素检测中SNAP和TTC两种检测方法的优劣问题。利用meta分析的方法对国内发表文献中的乳品中抗生素残留情况进行分析,找出我国地区乳品抗生素残留情况的特点和规律,旨为国内奶农、乳品生产企业和监管部门进行乳品安全管理和乳品抗生素检测提供参考和指导建议。利用Review Manager 5.3软件对中国部地区乳品抗生素残留情况以及SNAP法和TTC法检测情况进行meta分析。Meta分析结果显示,东部地区乳品抗生素残留情况比西部较好,而北部地区乳品抗生素残留比南部地区较差。对于乳品抗生素检测方法,其meta分析结果显示SNAP方法总体上优于TTC法。我国东南地区乳品抗生素残留情况比西北地区情况好,SNAP法对于乳品中抗生素检测更为精确。     

基于偏正态分布的随机效应meta回归

将随机效应meta回归模型进行推广,构造基于偏正态分布的随机效应meta回归模型．在模型中同时考虑偏倚和异质性,以及二者对合并效应估计和回归系数估计的影响．在该模型下,对合并效应量和回归系数采用加权最小二乘估计,并进一步修正为无偏估计．与以往基于正态分布的随机效应meta回归模型相比,该模型将偏倚进行量化,并从合并效应估计和回归系数估计中予以剔除,消除了偏倚对合并效应量和回归系数的影响．提出的模型较基于正态分布的随机效应meta回归模型可以有效提高合并效应量和回归系数的估计精度．     

Novel sericin‐fixing agent containing rare‐earth ion for weighting silk fiber

Silk fibers were weighted with different weight gain rate by using a novel sericin‐fixing agent containing rare‐earth ion. Laser Raman spectra, scanning electron microscope (SEM), and amino acid analysis were studied to characterize the structures of weighted fibers. Laser Raman spectra verified that the content of the highly oriented β‐sheet conformation decreased in the weighted fibers. Amino acid analyses showed that the content of polar amino acid increased with the increase in weight gain rate. SEM analyses showed that the sericin was successfully fixed on the surface of the fibroin. Moreover, the mechanical and dyeing properties of the weighted fibers were also investigated. The results indicate that there was no significant difference in breaking strength and elongation between the weighted fibers and the control; the equilibrium moisture content and the color strength value (K/S) of the weighted fibers increased with increasing weight gain rate.     

Finite element simulation of three‐dimensional angle‐interlock woven fabric undergoing ballistic impact

This paper presents finite element simulations of three‐dimensional (3D) angle‐interlock woven fabric (3DAWF) undergoing ballistic impact. A micro‐structure model of the 3DAWF was established at the fiber tow level. Incorporated with commercial finite element code, ABAQUS/Explicit, the ballistic impact damage of the 3DAWF was simulated and compared with that in the experiment. Residual velocities of the conically cylindrical steel projectile (Type 56 in Chinese Military Standard) with different strike velocities were calculated and verified with those in the experiment. There are good agreements of the impact damage of the 3DAWF and the residual velocities of the projectile between finite element results and experimental results. The acceleration fluctuation record of the projectile and the stress wave propagation in the 3DAWF obtained from the simulation reveal the impact damage mechanisms of the 3DAWF. The strain rate effect of the fiber tows on the ballistic performance are also discussed. Such a micro‐structure model could be extended to the design of the impact behavior of the 3DAWF composites.     

Fabrication of poly(vinylidenefluoride‐co‐hexafluoropropylene) nanofiber yarns by conjugate electrospinning

Conventional electrospinning is an efficient method to fabricate polymer nanofibers which are usually collected as non‐woven mats. Recently, in order to fabricate a nanofiber yarn, conjugate electrospinning has been developed using coupled spinnerets applied with two high electrical voltages of opposite polarities In this paper, poly(vinylidenefluoride‐co‐hexafluoropropylene) (PVDF‐HFP) nanofiber yarns are prepared by conjugate electrospinning. The effects of the concentration and delivery rate of polymer solution and the distance between coupled spinnerets on the structure of PVDF‐HFP nanofiber yarns are investigated. The structure of the nanofiber yarns is observed by scanning electron microscopy (SEM). The mechanical properties of the nanofiber yarns are measured by electronic fiber strength tester. The results show that the PVDF‐HFP nanofiber yarn consists of a large number of nanofibers aligned well along the longitudinal axis of the yarn, and the nanofibers have diameters ranging from several hundred nanometers to a few microns. The diameter of nanofibers in yarns increases with the increase in the polymer concentration, which significantly affects the structure of nanofiber yarns. The PVDF‐HFP nanofiber yarn electrospun from the polymer solution with a concentration of 45% has the highest tensile strength of 0.25 cN/dtex and an elongation of 180.13%.     

A new approach to de‐curling force of single jersey weft‐knitted fabric

In this work, the curling behavior of cotton single jersey weft‐knitted fabric was studied using a new non‐destructive test method. Eighteen series of dry‐relaxed weft‐knitted fabric samples were produced with three different yarn twist levels (724.5 tpm, 807 tpm, and 890 tpm), two yarn twist directions (Z and S), and three different loop lengths (2.7 mm, 2.85 mm, and 3.2 mm). Curling behavior was characterized in terms of curling distance (CD), de‐curling force, and de‐curling energy. The results show that weft‐knitted fabric samples with a lower loop length and higher yarn twist level exhibited higher de‐curling force and de‐curling energy. It is indicated that the de‐curling force of weft‐knitted fabric samples produced from the Z‐twist cotton ring‐spun yarn is higher than that of the samples produced from the S‐twist cotton ring‐spun yarn. The regression analysis results also illustrate that de‐curling force and de‐curling energy are non‐linearly correlated with edge CD, and variation trends follow polynomial equations. The result of this research suggests that the curling behavior of weft‐knitted fabric can be predicted in terms of de‐curling properties.     

Effect of heating–cooling cycle on the opto‐structural properties of low‐density polyethylene fibres using two‐beam interference microscopy

A hot stage attached with a two‐beam interference (Pluta) microscope was used to apply a heating–cooling cycle (HCC) on low‐density polyethylene fibres (LDPE). The variation of the refractive indices (n ^∥ and n ^⊥) with the temperature was carried out during the heating and cooling of the LDPE fibres. The activation energy (E _a) and thermooptic coefficient (dn/dT) were calculated for the investigated LDPE fibres. The spectral dispersion curves, percent crystallinity and orientation function were determined for the treated LDPE fibres. It was found that the HCC for LDPE fibre implies: a reversible behaviour of both optical and structural properties against temperature and an improvement in the fibre crystallinity.