EXPERIMENTAL RESEARCH ON VISCOELASTICITY OF HUMAN BLOOD- WITH REFERENCE TO THE EFFECT OF CELL HEMOTOCRIT     

Cai Shaoxi Wu Xi Xiao Jun Liu Yanhai Wu Yunpeng 《保鲜与加工》1992,(3):15-18

This paper describes a part of the experiments concerning the viscoelasticity of human blood, which are based upon the theories lead by the authors. The data from the experiments are compared with those in the literatures. The effect of cell hematocrit on viscoelasticity is especially discussed and a new viscoelasticity index is defined to eliminate this effect.  相似文献   

基于本构模型的颗粒饲料成型特性研究   总被引：1，自引：3，他引：1  

陈啸  孔丹丹  王红英  方鹏 《农业工程学报》2017,33(23):267-275

为研究饲料原料挤压成型特性,构建了非线性黏弹塑性颗粒饲料成型本构模型,针对主要饲料原料小麦,通过分析成型试验因素对其本构模型系数及其表征的流变学特性的影响,研究物料特性、加工参数等对小麦原料成型特性的影响规律,并分析了模型系数与颗粒成型质量的相关性关系。黏弹塑性本构模型由牛顿黏滞体(Newton viscous dashpot element)、应变硬化弹簧元件(strain hardening spring element)和库伦摩擦元件(Coulomb friction element)构成,基于小麦原料的实际成型试验完成模型构建;模型验证结果显示:数值结果中各应力区间模型决定系数R2在0.99以上,模型值与试验值较为吻合,相对误差总平均值为3.378%,并通过χ2检验进一步证明模型有效性;应用本构模型对小麦原料成型特性的分析结果显示,表征其流变学特性的模型系数表现出明显的应力函数规律,黏性系数绝对值随着挤压过程的进行逐渐减小,弹性模量值逐渐增大,集成塑性系数值则表现为先增后降,而各成型试验因素对模型系数产生了显著规律性影响,与宏观试验现象比较吻合;通过Pearson相关性分析可知颗粒成型密度、颗粒成型率、颗粒成型硬度等成型质量指标分别与黏性系数、塑性模量与弹性模量间达到了最高的相关系数,数值皆在0.80以上且为极显著相关性水平(P0.001),为基于本构模型对颗粒成型质量进行分析和控制提供依据。研究结果为颗粒饲料挤压成型特性研究提供了一种新方法和新角度,也为颗粒饲料的高效低耗生产和产品质量的改善提供基础数据和理论参考。  相似文献   

A rapid extensigraph protocol for measuring dough viscoelasticity and mixing requirement     

《Journal of Cereal Science》2017

The extensigraph is particularly useful in characterizing dough viscoelastic properties; however, testing throughput for standard method is low due to the prerequisite for farinograph water absorption, long dough resting and milling to prepare large amounts of flour. Therefore, a rapid extensigraph method was developed that reduced sample size (165 g wheat) for milling and more than tripled throughput. Wheat is milled in Quadrumat Junior mill with a modified sieving system. The resulting flour (100 g) was mixed with a pin mixer at constant water absorption to allow the evaluation of wheat genotypes at the absorption level they are expected to perform. Dough was subsequently stretched by an extensigraph after 15 min of floor time and 30 min resting. Strong correlations for extensigram R_max (r > 0.93), extensibility (r > 0.64) and area (r > 0.88) were found for the proposed method compared to the standard method. Mixing parameters (time and energy) obtained during dough preparation provided further information about dough strength and mixing requirement. By significantly reducing sample size requirement and increasing testing throughput, this rapid extensigraph method can be widely adopted in milling and baking industry and meets the need for a fast evaluation of dough strength in breeding trials.  相似文献   

番茄整果在常温贮藏中的蠕变特性试验   总被引：3，自引：0，他引：3  

陆秋君  王俊  黄会明  周莹 《浙江大学学报(农业与生命科学版)》2006,32(2):168-172

蠕变特性是评价番茄果实品质的一个重要指标.本试验应用Instron万能试验机对常温贮藏的整番茄进行了蠕变特性的试验,对蠕变特性四参数、压缩弹性模量E、坚实度Fi、糖度及pH值等指标的变化规律进行了分析.结果表明:蠕变特性的粘弹性系数与压缩特性指标出现先下降,后逐渐上升,至第9 d达到最高峰,然后呈急剧下降的趋势.在常温贮藏期间,番茄的糖度和酸度均缓慢增加.  相似文献   

Viscoelastic Model Analysis of In-situ Pressuremter Creep Test in Permafrost     

Zhang Hu  Zhang Jianming  Su Kai  Liu Shiwei 《保鲜与加工》2013,(6):22-27

In order to investigate the creep behavior of warm and ice-rich frozen soils, a number of pressuremeter tests were carried out in permafrost regions on the Qinghai-Tibetan Plateau with Menard pressuremeter. Then, the regression analysis results of the creep curves generated by Merchant model and relevant parameters were obtained. The test results indicate that the temperature plays a more important role than the water content in affecting the mechanical behavior of warm frozen soils. As pressure increases, the proportion of instantaneous strain in the total strain under each pressure decreases gradually. The regression results show that the instantaneous shear modulus increases linearly with decreasing temperature, but the delayed shear modulus as well as the viscous coefficient present a power function trend. Their peak values appear at the water content of 46%, which is rather different from the test result on lower temperature frozen soils.  相似文献   

Characterization of viscoelastic,shrinkage and transverse anatomy properties of four Australian hardwood species     

《Wood material science & engineering》2013,8(3):95-104

Abstract

Several key wood properties of four Australian hardwood species: Corymbia citriodora, Eucalyptus pilularis, Eucalyptus marginata and Eucalyptus obliqua, were characterized using state-of-the-art equipment at AgroParisTech, ENGREF, France. The wood properties were measured for input into microscopic (cellular level) and macroscopic (board level) vacuum-drying models currently under development. Morphological characterization was completed using a combination of environmental scanning electron microscopy and image analysis software. A clear difference in fibre porosity, size, wall thickness and orientation was evident between species. Viscoelastic properties were measured in the tangential and radial directions using dynamic mechanical analysis instrumentation. The glass transition temperature was markedly different for each species owing to anatomical and chemical variations. The radial direction showed higher stiffness, internal friction and glass transition temperature than the tangential direction. A highly sensitive microbalance and laser technology were used to measure loss of moisture content in conjunction with directional shrinkage on microsamples. Collapse shrinkage was clearly evident with this method for E. obliqua, but not with other species, consistent with industrial seasoning experience. To characterize the wood–water relations of E. obliqua, free of collapse, thinner sample sections (in the radial–tangential plane) are recommended.  相似文献   

穴盘水稻秧苗茎秆蠕变与应力松弛特性的试验研究   总被引：2，自引：2，他引：0  

马瑞峻  萧金庆  郑普峰  张亚丽  陈瑜  邱志 《农业工程学报》2018,34(13):43-53

为深入了解穴盘水稻秧苗茎秆拉伸过程中的力学特性,该文利用微控电子万能试验机对穴盘水稻秧苗茎秆常规拉伸、蠕变与应力松弛特性进行测试与分析。试验表明:常规拉伸一般有2次断裂,1次断裂前,应力-应变为线性关系,没有明显的屈服过程,且平均断裂应力大小随加载速率的增加而呈线性增加;拉伸蠕变和应力松弛过程分别利用伯格斯四元件模型和麦克斯韦五元件模型进行描述。通过对曲线进行拟合,得到相关的模型参数,基于选用的流变模型和本构方程,结合秧苗茎秆的生物体特点,分别对蠕变速率、蠕变柔量和应力松弛速率、应力松弛时间进行分析,结果表明:蠕变和应力松弛过程都是弹性动力与黏滞阻力之间彼此牵制的过程;蠕变过程产生与蠕变时间和初始应力呈正相关的塑性应变,应力松弛过程导致茎秆大分子链发生变化,均对秧苗茎秆造成一定损伤;秧苗茎秆内部含有柔嫩与粗壮2种组织结构。研究结果可为秧苗机械拔取的损伤评估和相关仿真分析提供参考。  相似文献   

粘度对超高温灭菌奶中脂肪球上浮的影响   总被引：1，自引：0，他引：1  

杭锋  孟令洁  任璐  郭本恒  龚广予  王荫榆  陈卫  张灏 《乳业科学与技术》2009,32(1)

基于物理反射模型的背反射光检测技术研究不同瓜尔胶添加量对超高温灭菌乳体系粘度及乳脂肪球的稳定性.以0.02%添加量(w/w)的K-卡拉胶作为乳蛋白稳定剂.蔗糖酯SE-15、羟基化改性大豆磷脂及分子蒸馏单甘酯按一定比例进行复配并以0.1%(w/w)进行添加以稳定乳脂肪,在此基础上分别添加0%、0.02%、0.03%、0.04%的瓜尔胶以增加超高温灭菌乳的粘度.分别测定了样品的粘度及顶部脂肪球的迁移动力学并比较4者之间的稳定动力学.实验结果表明,随着瓜尔胶添加量的增加,样品粘度亦随之增加,顶部的脂肪浮油速率呈降低趋势,瓜尔胶添加量为0.03%时样品的稳定性达到最大值.因此,增加粘度可以抑制乳脂肪球上浮速率、增加产品的稳定性.  相似文献   

加工番茄粘稠度性状的配合力和遗传力分析     

许向阳  关法春  康立功  张贺  李景富 《东北农业大学学报》2008,39(3):26-28

试验以加工番茄7个品系为试验材料,采用Griffing第2种方案配制21个杂交组合,对番茄粘稠度性状进行配合力分析和遗传力分析。结果表明,粘稠度性状一般配合力较高的亲本80、77和81,其杂交后的组合77×80、77×81的特殊配合力也最高;粘稠度性状是以基因的非加性效应为主,狭义遗传力较低,不宜早期时代进行选择。但杂种一代值具有超亲优势现象,存在杂种优势。因此,高粘稠度品种育种应以优势育种为主,辅之以杂交育种。  相似文献   

胶凝原油粘弹性的试验研究     

李传宪  李琦瑰 《油气储运》2000,19(10):42-44

用控制应力流变仪RS75对新疆、胜利、长庆等胶凝原油进行了粘弹性试验，结果表明，胶凝原油具有典型的粘弹性固体特征，如具有蠕变／恢复特性，以及复数模量│G^*│大，损耗角δ小的特性等。小振幅剪切振荡粘弹性参数，可反映不同状态下原油的流变结构特点。  相似文献