利用激光细度仪快速检测棉纤维细度的探究

为了解决传统棉纤维线密度测量方法效率低、稳定性差的问题,探讨采用激光细度仪对棉纤维进行测量,并选用经典线密度测量方法——中段切断法验证激光法的准确性。选择6种不同马克隆值的棉样进行测试,利用激光细度仪得到投入样品的有效根数和平均直径,并结合线密度的定重制计算出棉样的平均线密度。与中段切断称重法测得的线密度值进行对比,发现细度仪结果比中段切断称重法的稳定性要差,其中对于较低马克隆值棉样两者没有明显差异。认为:细度仪得到的平均直径、根数和马克隆值,与中段法结果进行线性拟合,并通过新样品验证回归方程的准确性,两种方法具有一定的线性相关性。     

茧丝纤度曲线函数模型的构建与分析

构建合理的茧丝纤度曲线描述模型是开展蚕品种选育、缫丝工艺制定和计算机模拟缫丝的重要基础。文章在分析了茧丝纤度曲线形态特征的基础上,将茧丝纤度曲线呈"细-粗-细,最末处最细"的特征归咎于蚕吐丝时吐丝口逐渐张开和绢丝液或吐丝力持续减弱的综合结果,提出采用Logistic函数和二次函数的复合函数来模拟茧丝纤度曲线。经非线性回归分析和模拟生成验证,确认该复合函数模型具有良好的适用性,有望成为新的茧丝纤度曲线描述和模拟生成方案。     

文摘天地

浙江省蚕茧业发展的SWOT分析及其战略选择；家蚕丝素重链基因（fib—H）部分序列克隆及结构分析；茧丝线密度变化的拟合与预测；纤维素的活化对其溶解性能的影响；Creora氨纶拉伸性能的研究；棉涤锦混纺闪色针织纱的开发     

时间序列分析上的丝绸之路

为了实现计算机模拟缫丝,模拟缫丝技术条件对生丝质量的影响,需要对茧丝纤度序列（也称茧丝纤度曲线）进行研究。从早期茧丝纤度曲线概念的提出,到用生成多维正态随机数的方法得到曲线系数,再到用时间序列分析的方法对其进行研究,经历了一个较长的时期。近期,研究人员通过对茧丝纤度序列的趋势波动量与随机波动量进行分离,得到有限长度零均值的非平稳时间序列,并提出了适用于非平稳时间序列的时变参数自回归（TV-PAR）模型,获得良好的效果。     

棉织物透气性能的预测研究

采用两种计算孔径的方法,分别计算出织物孔径dp、dh。在特定纱线线密度下,研究织物孔径和织物透气率之间变化规律。其次改变纱线线密度,观察纱线线密度变化对织物透气率大小的影响。利用Origin软件拟合织物透气率与纱线线密度、织物经纬纱密度、孔径dp或孔径dh之间的函数关系。研究结果表明,当孔径分别采用dp、dh用作拟合参数时,所得函数计算的透气率与实测透气率的相关系数分别为0.9927、0.9952。由此可见,所建立的拟合函数可用于全棉织物的透气性预测。对于孔径计算方法的选择,采用dh时要比采用dp时,透气率的预测精度略高。     

计算机最佳分段线性校正

本文介绍了一种最佳分段线性校正的工程方法。它基于一致逼近的原理,采用不连续折线一致逼近非线性曲线。把非线性问题转化成最佳分段线性问题,然后建立相关数据表,把查表和运算结合起来用于微处理机中进行最佳分段线性校正。     

指纹曲线的拟合

在指纹识别中经常遇到的一些残缺的指纹，如何从这些残缺的指纹中复原出完整的指纹。这是指纹处理的一项重要工作。给出了利用广义延拓法对图像指纹的残缺曲线进行拟合的方法，得出完整的指纹曲线，并通过指纹图像曲线进行了验证。     

基于分数阶模型的纱线蠕变性能模拟与预测

针对现有纱线拉伸力学模型描述不准确问题,以分数阶微积分模型对纱线拉伸行为进行分析。首先,引入分数阶微积分理论改进的黏壶模型建立了分数阶纱线蠕变模型,使用XL-2型纱线强伸度仪对不同线密度及不同张力纱线进行蠕变实验,获得纱线蠕变的全过程曲线。通过对不同线密度下的试验曲线进行回归分析得到了模型参数以及蠕变模型参数与施加张力大小的变化关系。最后,利用不同模型对不同张力的纱线蠕变曲线进行拟合和预测。结果表明:分数阶纱线蠕变模型,相比于三元件模型、整数阶模型和Burgers模型,具有结构简单、参数少的特点,并且对纱线蠕变的拟合和预测也具备较高的精度。     

酿酒酵母工程菌分批发酵产UMP动力学模型

对酿酒酵母工程菌产UMP的分批发酵动力学进行了研究。通过对Logistic方程、Leudeking-Piret方程和类Luedeking-Piret方程进行参数估计和非线性数据拟合,分别得到发酵过程中菌体干重、UMP产量、残糖含量动力学模型及模型参数。对拟合曲线进行分析,结果表明模型值与实验值拟合性良好,线性拟合度大于98%,所建立模型能较好的反映UMP的分批发酵过程。     

桑丝绫织物设计参数的探讨

统计分析桑丝绫织物的丝线线密度、经、纬纱线密度、织物紧度及缩率等规格设计参数的取值范围，与桑丝绫织物（β=1）的理论最大可织曲线进行比对，显示其结构区域特征。利用线性回归研究织物规格设计参数之间的相互关系，得到桑丝绫织物由成品质量设计其经纬纱线线密度与上机密度的简便方法，对桑丝绫织物设计有实用意义，也为此类织物计算机辅助设计建模提供数据支持。     

甲基丙烯酰胺接枝桑蚕丝接枝率的数学模型构建与定量分析

为建立蚕丝接枝率的定量分析方法,使用甲基丙烯酰胺(MAA)单体对桑蚕丝进行接枝反应,得到一系列不同接枝率的接枝蚕丝纤维组样.分别应用热重和红外光谱分析技术对系列接枝蚕丝纤维进行表征与分析发现,在表征曲线中出现了新的特征峰,且随接枝率的增加,新特征峰面积逐渐增大.采用Origin9.1数学分析软件中的Gaussian分峰...     

非线性曲线拟合法在食品应力松弛数据解析中的应用

通过非线性曲线拟合法解析硬质(火腿)、软质(奶酪)、鱼类(鲈鱼)、贝类(海螺)4种类型食品原料应力松弛曲线,并与传统的逐次近似法解析数据进行比较分析。结果表明：非线性曲线拟合法能够实现对广义Maxwell单元模型的拟合,可得到拟合程度高,稳定可靠的分析结果,而且操作简单、快捷,适合多种食品原料的应力松弛数据解析;对于水分含量高、黏弹性结构复杂的鱼类等食品,非线性曲线拟合法与逐次近似法相比更具优越性。     

Comparative evaluation of a new lactation curve model for pasture-based Holstein-Friesian dairy cows

Fourteen lactation models were fitted to average and individual cow lactation data from pasture-based dairy systems in the Australian states of Victoria and Tasmania. The models included a new "log-quadratic" model, and a major objective was to evaluate and compare the performance of this model with the other models. Nine empirical and 5 mechanistic models were first fitted to average test-day milk yield of Holstein-Friesian dairy cows using the nonlinear procedure in SAS. Two additional semiparametric models were fitted using a linear model in ASReml. To investigate the influence of days to first test-day and the number of test-days, 5 of the best-fitting models were then fitted to individual cow lactation data. Model goodness of fit was evaluated using criteria such as the residual mean square, the distribution of residuals, the correlation between actual and predicted values, and the Wald-Wolfowitz runs test. Goodness of fit was similar in all but one of the models in terms of fitting average lactation but they differed in their ability to predict individual lactations. In particular, the widely used incomplete gamma model most displayed this failing. The new log-quadratic model was robust in fitting average and individual lactations, and was less affected by sampled data and more parsimonious in having only 3 parameters, each of which lends itself to biological interpretation.     

Analysis of the effect of traffic exposure on the recovery properties of cut pile carpet using analytical and viscoelastic modeling

Viscoelastic models composing of different combination of spring and dashpot are usually used to explain the mechanical behavior of textile materials. In this work, a viscoelastic model was presented to analyze the effect of traffic exposure on the compression and recovery performance of the pile carpet. Wear test, performed by a Hexapod tumbling machine, was conducted to simulate the traffic exposure. Using a tensile tester, adjusted in compression mode, one cycle of compression–decompression was applied to the samples. The standard nonlinear model was presented to fit the experimental data. Best curve fitting based on the least square method was then used to fit the model to the experimental curve. Different attributions of compression were then analyzed and discussed. The results showed that the standard nonlinear model was fitted to the experimental curves with an acceptable coefficient of regression (R²). The district model parameters, i.e. the spring and dashpot constants, were both decreased as the wear cycles increased. At the higher level of wear cycles, the model parameters showed some increment. The initial compression modulus showed the same trend. This may be explained by the more compactness of the carpet at higher wear cycles. The decompression modulus, compression and the decompression work also decreased with the increase of wear cycles. However, no significant increase of the formers was observed at the higher wear cycles.     

生丝电子检验中线密度变异系数的分布

生丝纤度变异系数是生丝电子检验分级标准中的一项主要质量检验指标。为了在生丝电子检验中合理设计生丝纤度变异系数（CVeven和CV5m）分级标准,需要准确了解其分布形态。通过对6批生丝进行电子检测试验,调查电子检验中CVeven和CV5m的频数分布,利用卡方检验进行正态分布拟合检验,运用KS统计量检验方法进行混合正态分布拟合检验,并对两分布拟合度进行比较分析。结果表明：生丝纤度变异系数分布反映了生丝质量、缫丝企业的管理水平;生丝纤度变异系数（CVeven和CV5m）服从由两个正态分布组成的混合分布。     

Comparison of models for describing the lactation curve of latxa sheep and an analysis of factors affecting milk yield

The objectives of this work were 1) to compare the goodness-of-fit of empirical models of the lactation curve and 2) to analyze the factors affecting the shapes of the lactation curves, the parameters describing them, and the overall milk yield of Latxa dairy sheep. A total of 14,699 records from 2711 ewes, collected during three consecutive years (1995 to 1997) by the milk recording program of the Latxa ewe of the Basque Country (Spain), were used. Six mathematical models and three fitting procedures were compared. The estimation of model parameters by nonlinear fitting procedures was superior to that by linear regression methods. A nonlinear variable decay model fitted the data better than the other models, as judged by lower mean square prediction error, residual sums of squares, and a lack of first-order positive autocorrelation as assessed by the Durbin Watson coefficient. The effects of the flock, flock-year interaction, month of lambing, length of lactation nested within month of lambing, parity, and number of live lambs born had significant effects on the parameters of the model and the total milk yield (P < 0.01). The prediction of milk yield from the selected model was similar to the estimates obtained with the Fleischmann method currently used by the national breeding program for the Latxa breed.     

Stress Relaxation Test for Monitoring Post Mortem Textural Changes of Ice-stored Cod (Gadus morhua L)

ABSTRACT: The possibilities of using the stress relaxation test as a nondestructive method to monitor post-mortem textural changes of ice-stored cod have been evaluated. The stress relaxation tests were performed in gutted cod. Fish were compressed by 5% and deformation was kept constant for 60 s. The relaxation curves obtained were fitted to nonlinear and linear regression models. Nonlinear regressions with 2 or 3 exponential terms and the linear regression model could be fitted to the relaxation curve of ice-stored cod, although the three-terms exponential models gave the best results for assessing the quality of ice-stored cod (maximum relative difference ≦ 2% and R 2 > 0.999). The highest differences were found between pre-rigor and in-rigor states.     

离子色谱法测定泡菜中亚硝酸盐的测量不确定度评定

为探索不同处理方法对化学测量不确定度评估精度的影响,分别用一般的线性拟合法和较严密的非线性拟合法评估校准曲线拟合浓度的不确定度分量,用一般的体胀系数法和较严密的密度修正法评估溶液体积变化的不确定度分量,用近似算式和较严密的算式评估加标回收率的不确定度分量。结果显示：严密法得到的扩展不确定度的精度较一般法高;对于接近符合限的检测结果,严密法可判定亚硝酸盐含量合格,而一般法无法判定。评估者只要遵循检测过程,按实际数据评估,则可获得较高且合理的评估精度。     

柞叶染料对柞蚕丝织物的染色及其吸附动力学研究

为有效利用废弃资源,制备生物基来源的功能性纺织品,采用柞树落叶为原料提取染料,探讨该染料对柞蚕丝的染色性能,测试了染色柞蚕丝织物的抗紫外线性能及染色牢度,研究了柞叶染料在柞蚕丝上的吸附动力学机制,对染色动力学曲线进行拟合并计算动力学参数。结果表明：柞叶染料在柞蚕丝上的提升性能良好,可以染得深浓色泽,且所测定各项色牢度均达到3级以上,最佳的染色条件为pH值3.0,在98℃下染色60 min;柞叶染料在柞蚕丝上的吸附动力学机制符合准二级动力学模型,随着染色温度升高,染料在纤维上的吸附速率常数及平衡吸附量均增大,半染时间缩短;染色织物具有抗紫外线性能,且其紫外线防护系数(UPF值)随着染料用量的增大而提高,当染料用量大于或等于7.5%(o.w.f)时,染色柞蚕丝织物的UPF值可达到40以上。     

Predicting initial base curve of the rigid contact lenses according to Javal keratometry findings in patients with keratoconus

PurposeTo find an appropriate correlation between the base curve (BC) of rigid gas permeable (RGP) contact lenses and manual keratometry findings in Iranian patients with keratoconus (KCN) in order to simplify the fitting process, reduce the time, and lower the costs.MethodThis retrospective study was done in 121 eyes of 69 patients with KCN fitted with a specific trial set of RGP contact lenses over a 7-year period. The specifications of the final lens parameters included power, total diameter (1), and BC, the first two of which were fixed in all of the lenses in the trial set while BC was changed in 0.1-mm steps. Javal keratometer was used to measure keratometric values. The final fit assessment was performed based on the standard criterion of "three-point touch".ResultSingle and multiple linear correlations were done and the result was the following equation: BC = 2.455 (constant of the final multiple regression model) + 0.280 (steep keratometry) + 0.368 (flat keratometry) + 0.047 (corneal astigmatism)ConclusionThe advantages of this study include simplifying the RGP fitting process, reducing the examination time, lowering the costs, enhancing the confidence of the examiners and patients, easier lens fitting in remote places where more advanced devices are not accessible.