Prediction of warp and weft yarn crimp in cotton woven fabrics

The aim of this study was to develop statistical models for the prediction of warp and weft crimp percentage of cotton woven fabrics. The developed models are based on the empirical data obtained from carefully developed 60 fabric samples with different yarn linear densities, fabric densities, and weave designs. The predictability and accuracy of the developed models was assessed by correlation analysis of the predicted and actual crimp values of another set of eight fabric samples which was not used for the development of models. The results show fairly good capability and accuracy of the prediction models.     

Study of tensile properties of plain-woven fabrics in all-directional using energy method,Part II: experimental verification

Abstract

In the previous part of this series, ‘Comprehensive Tensile Modulus (CTM)’ was introduced as an important modulus to express the force-elongation behavior of plain-woven fabrics when the force is imposed on the fabric and extended it simultaneously in all directions. A theoretical model was presented to predict this modulus in the initial elastic region. In order to verify the accuracy of the model, a novel tensile test method was developed to measure load-extension curve of the fabric samples under the proposed loading condition. Thereafter, six plain-woven fabrics were produced with different raw materials and densities then were washed and dried to reach the relaxed state. Fabric samples were tested using the new method. The fabric’s experimental Comprehensive Tensile Modulus (CTMs) were determined from the results of the tests in all directions by the nine-point central difference method, and the calculated data were analyzed statistically to obtain the experimental CTM of fabrics. Reasonable agreement between theoretical and experimental results confirmed that the generated model is capable to predict the CTM index as a tensile property of plain-woven fabrics, adequately. The comparison between results of the theoretical model and experimental test shows that maximum error of prediction is 8.5% which is recorded for the grey fabric sample constructed from the OE Cotton yarn with nominal yarn count 24 Ne. Also, maximum experimental comprehensive tensile modulus (17.9 N/mm) is for the grey fabric sample constructed from the high tenacity continuous filament of Nylon with nominal yarn count 900den, in one millimeter extension with maximum modulus in warp and weft directions, that is, 5.6 N/mm and 6.6 N/mm in the same extension in the initial linear elastic region, respectively.     

仓储粮堆内热湿耦合传递的数值模拟

本文通过理论分析与数值模拟相结合的方法,以典型吸湿性多孔介质—小麦为研究对象,根据小麦吸湿和解吸湿曲线,建立了吸湿性多孔介质内部热湿耦合传递的数学模型,通过与相关实验数据比较验证了数学模型的合理性。基于有限元的方法模拟分析了外界气温和小麦分别为273K(0℃)和293K(20℃),小麦初始水分为14%和18%时直径为10m高度为10m的充满小麦的圆柱仓内部热湿迁移过程,重点探究了近似冬季和夏季仓储粮堆内部温度和水分的动态变化规律。研究结果表明,冬季工况下水分从粮堆内部向顶部和右侧壁面迁移,聚集在相对狭窄的壁面边界附近,形成低温高水分区域,最大水分值出现在右上部侧壁面附近。夏季工况下水分从顶部和侧面向内迁移,而内部又朝右上部区域扩散,形成较宽的高温高水分区域(r <4.5m, 8.0m 相似文献   

Evaluation of convective heat transfer coefficient between fluids and particles in suspension as food model systems for natural convection using two methodologies

This study was conducted to evaluate the convective heat transfer coefficient between Newtonian and non-Newtonian fluids and food particles inside of a glass vessel and to assess the effect of controlled variables: convection phenomena, heating temperature, immersion fluid, and different food particles. The coefficient was evaluated from the sample temperature as a function of the heating time by two approaches: a lumped parameter method and an analytical methodology. High values corresponded to heating in Newtonian fluids (70–181, 57–248 W/m² K), and lower corresponded in non Newtonian fluids (31–169, 28–167 W/m² K). Similarly, major heat transfer coefficient corresponded to the heating of mushrooms (32–110, 28–132 W/m² K), followed by tomatoes (30–181, 35–183 W/m² K) and potatoes (31–148, 34–248 W/m² K), respectively. Fluid properties were more important than the thermal properties of the particles. This coefficient was higher at 85 °C in both types of fluids. Both methods generated satisfactory values, but the analytical approach showed more accuracy.     

Air permeability and bursting strength of weft-knitted fabrics from glass yarn. Part II: knit architecture effect

In this study; the effects of loop, skip, and tuck stitch types, and weft-inlay yarn, on air permeability and bursting strength of weft-knitted fabrics from glass yarn were revealed. Due to clockwise rotation of wales and their arrangement being one on top of the other, besides the dramatic shortening of fabrics after their removal from the machine; fabrics with tuck stitches exhibited the highest stitch density, fiber content, and the shortest loop length. This caused the lowest air permeability and the highest bursting strength. Contrary to expectations, weft-inlay yarn did not contribute to bursting strength as much as tuck stitch did. An overall negative correlation between air permeability and bursting strength was disrupted by structures with tuck stitches. While tuck stitches from cotton yarn increased air permeability and decreased bursting strength in previous studies; this study indicated that tuck stitches from glass yarn decreased air permeability and increased bursting strength.     

Analysis of warp-knitted fabric structure. Part II: theoretical study on initial modulus of warp-knitted fabrics (tricot,locknit, and satin)

In the first part of this series, a 3D straight line model was presented for the geometry of two-guide-bar warp-knitted fabrics. In this part, first, the variation of unit cell geometry under uniaxial tension in the range of elastic deformation is investigated. In the present study, the energy method and Castiglianos's theorem were used to derive the fabric's initial modulus. Energy terms which are considered in this study are extension, bending, and compression energies. Also, the friction phenomenon is taken into account by using frictional energy term. For this purpose, the loop of each bar is divided into eight elements. Free-body diagrams of elements are drawn to show the relative magnitude and direction of all forces acting upon an object in a given situation. After obtaining the force details, strain energy of each element is calculated. Finally, the initial modulus of warp-knitted fabrics is obtained. To verify the model, samples of tricot fabrics were produced and tested. Results showed that the generated model can predict precisely the initial modulus of aforementioned warp-knitted structures.     

Heat transfer and lethality considerations in aseptic processing of liquid/particle mixtures: A review

Consumer awareness and demand for nutritious yet inexpensive food products call for innovative processing techniques that have both safety and quality as primary objectives. These challenges appear to have been met by aseptic processing techniques, especially for liquid and high‐acid foods. However, the extension of aseptic processing principles to low‐acid foods containing discrete particles in viscous sauces has not been approved by regulatory agencies, particularly in North America. This apparent limitation is due primarily to the lack of adequate temperature monitoring devices to keep track of particles in dynamic motion, as well as to the residence time distribution of particles flowing in the continuous heat‐hold‐cool sections of the aseptic processing system. These problems have prompted active research to describe the phenomenal behavior of particulates through sound mathematical modeling and computer simulators. The accuracy of mathematical models depends heavily on how accurate input parametric values are. These parameters include the thermophysical properties of the carrier fluid and particles, as well as the aseptic processing system characteristics in relation to residence time distribution and the fluid‐to‐particle interfacial heat transfer coefficient. Apparently, several contradictory findings have been reported in the literature with respect to the effect of various processing parameters on the above‐mentioned input parametric values. The need therefore arises for more collaborative studies involving the industry and academia. This review brings to perspective, the current status on the aseptic processing of particulate foods with respect to the critical processing parameters which affect the fluid‐to‐particle convective heat transfer coefficient associated with particulate laden products.     

Preweaned heifer management on US dairy operations: Part II. Factors associated with colostrum quality and passive transfer status of dairy heifer calves

Passive transfer of immunity is essential for the short- and long-term health of dairy calves. The objective of this study was to evaluate factors associated with colostrum quality and passive transfer status of US heifer calves. This study included 104 operations in 13 states that participated in the calf component of the National Animal Health Monitoring System's Dairy 2014 study. This 18-mo longitudinal study included 1,972 Holstein heifer calves from birth to weaning. Multivariable mixed linear regression models were selected using backward elimination model selection after univariate screening to determine which factors were associated with colostrum IgG and serum IgG concentrations. The mean colostrum IgG concentration was 74.4 g/L with 77.4% of colostrum samples having IgG concentrations >50 g/L. The final model for colostrum IgG included colostrum source and a categorized temperature-humidity index value (cTHI) for the month before calving. Mean colostrum IgG concentrations were highest for dams in third and higher lactations (84.7 g/L) and lowest for commercial colostrum replacers (40.3 g/L). Colostrum IgG concentrations were highest for cTHI ≥70 (72.6 g/L) and lowest for cTHI <40 (64.2 g/L). The mean serum IgG concentration was 21.6 g/L, with 73.3% of calves having serum IgG concentrations >15 g/L. The final model for serum IgG concentration included region, heat treatment of colostrum, colostrum source, timing to first feeding, volume of colostrum fed in the first 24 h, age of the calf at blood sampling, and colostrum IgG concentration. Mean serum IgG concentrations were highest for calves that received colostrum from first-lactation dams (25.7 g/L) and lowest for calves fed commercial colostrum replacer (16.6 g/L). Serum IgG concentrations were higher for calves fed heat-treated colostrum (24.4 g/L) than for calves fed untreated colostrum (20.5 g/L). Serum IgG concentration was positively associated with the volume of colostrum fed in the first 24 h and colostrum IgG concentration, and negatively associated with the number of hours from birth to colostrum feeding and age (days) at blood collection. Dairy producers should be encouraged to measure the quality of colostrum before administering it to calves and to measure serum IgG or a proxy such as serum total protein or Brix to evaluate passive immunity and colostrum management programs.     

Improving passive transfer of immunoglobulins in calves. II: Interaction between feeding method and volume of colostrum fed

The objective of this study was to investigate the effect of method of feeding (nipple bottle vs. esophageal tube feeder) on passive transfer of immunoglobulin (Ig) G when either a large or small volume of colostrum was fed. Newborn bull calves were removed from the dam before suckling and randomly assigned to 1 of 4 colostrum replacer (CR) treatment groups: 1.5 L (100 g of IgG) of CR fed using a nipple bottle (group 1; n = 24); 1.5 L (100 g of IgG) of CR fed using an esophageal tube feeder (group 2; n = 24); 3.0 L (200 g of IgG) of CR fed using a nipple bottle (group 3; n = 24), or 3.0 L (200 g of IgG) of CR fed using an esophageal tube feeder (group 4; n = 25). Blood samples collected at 24 h of age showed that serum IgG levels were significantly greater in calves fed large (3 L) volumes of CR compared with calves fed small (1.5 L) volumes of CR, regardless of feeding method. These differences were attributed to the larger mass of IgG ingested by calves fed 3 L of CR (200 g of IgG) compared with calves fed 1.5 L of CR (100 g of IgG). For calves fed small (1.5 L) volumes of colostrum, serum total protein (TP, g/dL), serum IgG (IgG, mg/mL), acceptable passive transfer rates (APT, %), and apparent efficiency of absorption of IgG (AEA, %) were significantly greater for calves fed with a bottle (TP = 5.3 g/dL; IgG = 12.5 mg/mL; APT = 100%; AEA = 51.1%) compared with calves fed with an esophageal tube feeder (TP = 5.0 g/dL; IgG = 9.8 mg/mL; APT = 41.7%; AEA = 40.5%). However, for calves fed large (3 L) volumes of colostrum, there was no difference in passive transfer indices for calves fed with a bottle (TP = 5.8 g/dL; IgG = 19.7 mg/mL; APT = 100%; AEA = 41.1%) compared with calves fed with an esophageal tube feeder (TP = 5.9 g/dL; IgG = 18.7 mg/mL; APT = 100%; AEA = 39.0%).