加料段固体塞的力学模型及其几何参数对输送能力的影响

以科学假设为基础，建立了单螺杆注射机加料段固体塞的力学模型，据此讨论了该段螺杆的几何参数，并给出了不同的几何参数在不同的取值范围内对加料段输送能力的影响，对注射机的发展具有理论指导意义。     

Modelling of heat transfer in a climbing-film evaporator: Part I

The absence in the literature of precise performance details and of any relationship between the heat transfer, the operating conditions and the physical and dynamic properties of the liquor fed to a climbing-film evaporator led us to develop a mathematical model to evaluate the performance of such an evaporator.The theory based on heat and mass balance equations is presented in this part of the paper: this model is validated by application to a pilotscale single-tube evaporator in part II. In part III the model is used to predict the performance of bigger industrial evaporators.     

基于DSP的纸张缺陷实时检测系统设计

基于DSP的纸张缺陷检测系统,分别对该系统的硬件和软件部分进行介绍。硬件部分采用高性能的DSP芯片作为图像处理的核心部分,为缺陷检测的实时性提供了保证;软件部分采用支持向量机算法,克服了传统方法的大样本要求和维数灾难及局部极小问题,又把非线性空间的问题转换到线性空间,降低了算法的复杂度,提高了计算速度。通过将支持向量机识别算法嵌入到高性能DSP芯片中,很好地实现了纸张缺陷的实时检测。     

高浓度锥形磨浆机力学模型

分析了高浓度锥形磨浆机磨浆区内的受力情况,提出了一种相应的力学模型。由于在高浓磨浆过程中,纸浆纤维除了受到磨盘作用力以外,还受到纤维间的作用力,故该模型由两大部分组成。其中,由于磨盘采用平面与锥面相结合的方式,为简化模型,在分析磨盘对纤维的作用力时,将平磨区和锥磨区分别考虑。     

注塑模具典型部件快速设计系统的开发

随着产品结构的复杂化和外观的多样化,注塑模具中典型部件的使用越来越广泛,而典型部件的设计建模工作对模具设计效率的影响较大。文章基于UGNX开发了注塑模具典型部件快速设计系统,该系统主要由典型部件管理系统和数据管理系统2个部分组成。系统的开发采用了系列关键技术,并为数据管理系统开发了大量数据模型,将以标准件为主体内容提升到以典型部件为主体内容,从而大幅提高了模具设计效率。图7参9     

工业发酵测控系统设计

设计了一套基于西门子PCS7及其BATCH配方系统的发酵过程测控系统,同时通过MES系统和报表系统来实现数据的集中管理。该系统由网络部分、硬件部分、软件部分以及数据处理部分组成。其中网络部分采用双层冗余环网结构,硬件部分采用CPU400冗余结构,软件设计部分采用PCS7和BATCH,数据处理部分采用MES和报表系统。各部分自下而上地构成了整个发酵测控系统,实现工业发酵的过程控制。     

Estimating the energetic cost of feeding excess dietary nitrogen to dairy cows

Feeding N in excess of requirement could require the use of additional energy to metabolize excess protein, and to synthesize and excrete urea; however, the amount and fate of this energy is unknown. Little progress has been made on this topic in recent decades, so an extension of work published in 1970 was conducted to quantify the effect of excess N on ruminant energetics. In part 1 of this study, the results of previous work were replicated using a simple linear regression to estimate the effect of excess N on energy balance. In part 2, mixed model methodology and a larger data set were used to improve upon the previously reported linear regression methods. In part 3, heat production, retained energy, and milk energy replaced the composite energy balance variable previously proposed as the dependent variable to narrow the effect of excess N. In addition, rumen degradable and undegradable protein intakes were estimated using table values and included as covariates in part 3. Excess N had opposite and approximately equal effects on heat production (+4.1 to +7.6 kcal/g of excess N) and retained energy (?4.2 to ?6.6 kcal/g of excess N) but had a larger negative effect on milk gross energy (?52 to ?68 kcal/g of excess N). The results suggest that feeding excess N increases heat production, but more investigation is required to determine why excess N has such a large effect on milk gross energy production.     

化工热力学在测定织物热阻中的应用

对润湿状态下织物热阻的研究，能更好的了解人体显性出汗后服装热阻的变化。根据化工热力学中平壁热传导理论，研究了润湿棉织物热阻的变化。通过理论得知，局部润湿织物的总热阻的倒数等于润湿部分和未润湿部分热阻倒数之和，这与实测结果吻合较好。对着装后润湿服装热阻进行了预测。     

Activation Volume from Stress Relaxation Curves in Raw and Cooked Potato

Abstract

Stress relaxation in two varieties (Nicola and Panda) of potato tubers (raw and cooked) was studied with the aim to specify fine structure of the activation volume obtained during the test. It is shown that activation volume decreases during the most part of stress relaxation test. The whole test was divided into five parts with quasi‐linear plots of activation volume vs. the actual stress. Different strain rates used in the pre‐stress (PS) part influenced mainly two first parts of the plot. Part 3 plays crucial role in the whole stress‐relaxation process. In raw state, this part is relatively insensitive to the variety and its slope decreases with increasing PS (from about 3 to about 2). In cooked state this part depends on the tested variety. The slope of the Relative apparent activation volume (RAAV)–Relative actual stress (RAS) plot in part 3 is changed dramatically with increasing pre‐stress in cooked Nicola. This is the main source of big difference in the slope and in this manner also in relaxation rate between cooked Nicola and cooked Panda.     

Alkali treatment on nettle fibers

This work deals with alkali treatment on nettle fibers. The first part of this work examines structure and properties of alkali-treated nettle fibers, while the second part reports on optimization of alkali treatment to improve tensile properties of nettle fibers. In this part, the alkali-treated nettle fibers were examined for their chemical, structural, physical, and mechanical characteristics and compared to untreated fibers. The alkali treatment appeared to remove lignin from the fiber, thereby resulting in increase in its crystallinity, improvement in its appearance, and decrease in its width and linear density. The untreated fiber was quite strong but less flexible and less extensible. A mild alkali treatment resulted in increase in tensile strength and elongation at break, without much changing initial modulus. On the other hand, a severe alkali treatment resulted in reduction in fiber strength as well as initial modulus without much change in elongation at break.     

Colour stabilization of red wines by microoxygenation treatment before malolactic fermentation

Microoxygenation allows the addition of small, continuous and controlled amounts of oxygen, in order to improve wine quality. Then, the effect of this treatment on colour stabilization and phenolic composition was studied. Four single varietal red wines were elaborated during three consecutive vintages. One part of them was microoxygenated before malolactic fermentation, the other part being maintained in stainless steel tanks without microoxygenation.     

The influence of cyclic deformation on the strength and elongation at break of carded and combed wool yarns

There are various factors that influence yarn strength. Yarn breaking is due to fiber breakages and fiber’s slippages. In reality, a part of the fibers slip while the other part breaks. In this study, we have shown that fatigue yarn, resulting in a fundamental way impact on the number of breaks on the weaving machine, and sometimes on the physical properties of fabrics. Given the importance of the issue and the very limited directed research number in this direction, a tests series were carried out with the aim to highlight the changes to the physical characteristics of the yarn resulting from mechanical treatment comparable to that which they are subjected on the weaving machine. In the first part of our investigation, the residual deformation, tensile strength, and elongation at break of combed and carded threads were measured. In the second part, the influence of the extensions number, their amplitudes, and frequencies were analyzed. In order to examine the influence of these parameters, carded and combed yarns, with different characteristics were prepared. Therefore, based on the separate treatment results of three test series, it appears that: the warp yarns subjected to repeated extensions undergo the phenomenon of fatigue. Yarns fatigue reduces their elasticity and resistance and it is the cause for break yarn during weaving. The fatigue of wool yarns is very low compared to other textile materials.     

基于西门子S7-300的干燥部DCS应用一例

介绍了西门子S7-300在造纸车间干燥部DCS的应用,主要包括网络结构、硬件组成、控制系统及专家算法.该系统实现了整个干燥部的自动控制,并降低能耗.     

13—AN INVESTIGATION OF THE TAPER OF COTTON FIBRES. PART III: VARIATION IN THE MECHANICAL PROPERTIES OF A COTTON FIBRE ALONG ITS LENGTH

The pattern of distribution of the mechanical properties and structural reversals along the fibre and their dependence on the fibre profile are reported in this paper. Experiments on twelve cottons showed that both the fibre tenacity and the percentage elongation increased steadily from the root part to the middle region and then decreased to a minimum value at the tip part of the fibre. The decrease in tenacity from the middle to the tip part of the fibre was found to be influenced by the fibre profile. The structural reversals increased from the root to the tip through the middle, and the maximum variation was observed in fibres having the highest uniformity in the cross-sectional shape of the fibre along its length. The variation in the structural reversals is shown to be a factor responsible for the observed distribution of tenacity along the fibre.     

《世界动物卫生组织传染病诊断PCR方法验证和质量控制指南》摘译

本文摘译自世界动物卫生组织(OIE)2008年出版的《陆生动物手册》第1.1.5章中关于核酸检测方法验证和质量控制的内容。世界动物卫生组织成立于1924年,主要职能是收集并通报全世界动物疫病的发生发展情况及相应控制措施;促进并协调各成员加强对动物疫病监测和控制的研究;制定动物及动物产品国际贸易中的动物卫生标准和规则。该章节由A-G共7部分组成。A部分是对常规分子诊断技术的介绍;B部分介绍核酸检测方法验证原则;C-G部分是方法验证过程的具体指南。由于篇幅所限,本文对A部分的综述性内容略去,重点围绕方法验证的具体流程进行摘译。目前,我国生物学检测方法(以PCR方法为主)验证的相关研究和标准化程序的制定正处于起步阶段。本文可作为我国食品分析专业人员研发和验证分子生物学检测方法提供借鉴。     

复合材料单边缝合机械手系统的机构动作规划与分析

为了能够在复合材料预制件的单边缝合操作过程中,获得预期理想的缝合线迹,本文针对单边缝合机械手中的引线、钩线及挑线机构在时间上的动作配合关系进行了设计与规划,通过分析机构转角与针杆位移的一般关系,确定了曲柄转角之间相位差的关系式,并利用仿真软件对各机构的位移变化规律进行了分析,仿真结果中引线、钩线及挑线机构在几个特殊时刻的位置,反映了三者在时间上的动作配合关系,验证了动作规划的合理有效性,为设备在工作中的调试并形成预期理想的线迹提供了理论参考。     

Appetite,hunger, and satiety in the elderly

Food intake declines with age and the elderly frequently report a decrease in appetite. Social and physical factors as well as decreased energy expenditure may be part of the explanation for the decreased food intake; however, it is possible that changes in hunger mechanisms are also involved, but more studies similar to those conducted on thirst are needed. The consumption of a varied diet depends in part on sensory‐specific satiety, that is, the decrease in the pleasantness of a food as it is consumed. We have shown that sensory‐specific satiety changes with age such that it was absent in individuals over the age of 65 and this could be part of the explanation of why the elderly consume more monotonous diets. Additional basic studies on how aging affects the controls of food intake will suggest ways to improve the nutritional status of the elderly.     

Development of mathematical model to predict vertical wicking behaviour. Part I: flow through yarn

Theoretical models have been proposed in this article (Parts I and II) to predict the vertical wicking behaviour of yarns and fabrics based on different fibre, yarn and fabric parameters. The first part of this article deals with the modelling of flow through yarn during vertical wicking, whereas the second part deals with the modelling of vertical wicking through the fabric. The yarn model has been developed based on the Laplace equation and the Hagen–Poiseuille’s equation on fluid flow; pore geometry has been determined as per the yarn structure. Factors such as fibre contact angle, number of filaments in a yarn, fibre denier, fibre cross‐sectional shape, yarn denier and twist level in the yarn have been taken into account for development of the model. Lambertw, a mathematical function, has been incorporated, which helps to predict vertical wicking height at any given time, considering the gravitational effects. Experimental verification of the model has been carried out using polyester yarns. The model was found to predict the wicking height with time through the yarns with reasonable accuracy. Based on the proposed yarn model, a mathematical model has been developed to predict the vertical wicking through plain woven fabric in the second part of this article.