纺纱过程中的几种特殊规律波的分析

文章指出了圈条波、加捻波、卷绕波等三种特殊规律波的形态,分析了产生原因,以及应该采取的措施。     

花生油高频剪切黏度超声检测

为对多次高温加热食用油品质进行评价,以反复煎炸花生油为研究对象,基于超声水平剪切波(SH波)在固体/黏弹性液体界面的复反射系数与液体黏弹性模量、黏度系数等关系模型,以固体/空气界面为参考,采用固/气、固/液界面回波对比方法,测量了不同劣化状态花生油在室温时的剪切黏度,并与流变仪测试结果进行比较。结果表明,超声SH波与流变仪均很好地反映了样品黏度随加热次数的变化关系。研究证明超声方法在线评价油品劣化状态具有可行性。     

纺纱过程中的几种特殊规律波及其分析

分析纺纱中圈条波、加捻波、卷绕波等特殊规律波的形态及其产生原因，同时提出要将“规律波”同“机械波”区别开来。探讨纤维通道、测试环境、设备器材、纺纱过程中的张力牵伸、工艺参数等对规律波的影响，为解决生产中出现的相关问题也提出了建议。     

石墨烯/磁性颗粒复合吸波材料的研究进展

石墨烯具有独特的二维材料性质,单以石墨烯作为功能粒子制备的吸波材料,吸波性能未达到预期值。为了开发"薄、轻、宽、强"的吸波材料,将不同磁性材料与石墨烯复合,可以改善单一石墨烯吸波材料的缺陷。分析了目前不同石墨烯/磁性颗粒复合吸波材料的吸波性能,主要介绍了石墨烯/磁性颗粒复合吸波材料的国内外最新研究进展,探讨了石墨烯/磁性颗粒复合材料的研究趋势。     

几种常见假波的分析与判断

简单介绍了纺纱生产和波谱试验中常出现的几种假波,如圈条效应波、粗纱加捻波、细纱张力波等.详细叙述了每种假波产生的原因,以及分析和判断方法.认为波谱分析相当复杂,必须仔细甄别,并应通过一定方法进行验证.     

低速冲击下纺织复合材料应力波平面传递研究

研究低速冲击下应力波在纺织复合材料中的传递特性。设计了低速冲击应力波测试平台,测试了应力波横向传递幅值在不同纤维材料和织物组织的纺织复合材料中的传递情况。试验结果表明:应力波在纺织复合材料平面传递时,其波幅随距离增加逐渐衰减;应力波在同种材料的单向布复合材料中的平面传递速度较机织物的快;在试验的碳纤维、玄武岩、超高分子量聚乙烯中,超高分子量聚乙烯复合材料应力波传递最快。认为:单向布复合材料较机织物复合材料更有利于应力波的平面传递和能量的扩散;应力波在超高分子量聚乙烯复合材料的平面传播速度较碳纤维、玄武岩复合材料快。     

纸基吸波材料的制备及其电磁性能探究

通过造纸法制备了一种可用于制备吸波蜂窝的纸基吸波材料,分别选用短切碳纤维(CF)、短切碳化硅纤维(SCF)和碳纳米管(CNT)作为吸波剂,对位芳纶浆粕(PPTA)作为基体,对比了不同吸波剂及其用量对纸基吸波材料电磁参数及吸波性能的影响。结果显示,吸波剂用量(对绝干基的质量分数)在0.1%~50%的范围内,SCF-PPTA纸基吸波材料的复介电常数实部小于CF-PPTA和CNT-PPTA纸基吸波材料的。当吸波剂用量大于3%时,CNT-PPTA纸基吸波材料的介电损耗大于另外2种材料的。当吸波剂用量分别为1%、20%和3%时,对应CF-PPTA、SCF-PPTA和CNT-PPTA纸基吸波材料的反射率最低分别可达-15.08、-28.49和-13.69d B,此时纸基吸波材料对应的厚度分别为2.45、4.35和2.98 mm。     

聚吡咯与石墨烯复合吸波材料的研究进展

为分析聚吡咯与石墨烯复合吸波材料的研究现状,首先阐述聚吡咯与石墨烯复合吸波材料的制备方法,介绍聚吡咯与石墨烯复合吸波材料的吸波机理,以及评价其吸波性能的重要电磁参数.然后分析影响聚吡咯与石墨烯复合吸波材料吸波性能的因素.系统归纳聚吡咯与石墨烯复合吸波材料的近期研究进展.最后对聚吡咯与石墨烯复合吸波材料的未来发展进行展望...     

利用推广的F一展开法求解（2＋1）维ZK方程

利用推广的F_展开法,研究了（2＋1）维ZK方程,获得了该方程的一些行波解和双周期波解．当模数优-0和m-1时,得到相应的单周期波解和孤立波解,从而丰富了该方程解的范围．     

天线罩用透波材料的研究进展

随着我国国防事业的快速发展,天线罩用透波材料成为材料领域的研究热点。天线罩用材料需保证飞行器在各种恶劣环境下的正常工作。为便于天线罩材料的选择和使用,本文综述了天线罩用透波材料的基本性能要求,概述了无机非金属透波材料、有机透波复合材料在国内外的研究现状,并详细介绍了陶瓷基透波材料与透波复合材料中常用的增强纤维和树脂基体,在此基础上提出了天线罩用透波材料目前存在的问题以及今后的发展方向。     

Design of falling-film evaporators in the dairy industry

The design of falling-film evaporators for dairy products has hitherto been based on empirical correlations for the heat transfer in the evaporator tubes. With a one-tube evaporator experiments with whole and skim milk were performed to determine the heat transfer and pressure drop in evaporator tubes. Two evaporation regimens are important for dairy products: convection boiling at lower heat fluxes and nucleate boiling at larger heat fluxes. Correlations have been derived. Based on the results obtained, a computer program, EvaDes (Evaporator Design), for the optimal design of multistage falling-film evaporators for dairy products has been developed. It quantifies the heat-transfer area of the stages for different arrangements, process conditions and dimensions of the evaporator tubes.     

Influence of heat transfer with tube methods on measured thermal inactivation parameters for Escherichia coli

The purpose of this study was to investigate the influence of heat transfer on measured thermal inactivation kinetic parameters of bacteria in solid foods when using tube methods. The bacterial strain selected for this study, Escherichia coli K-12, had demonstrated typical first-order inactivation characteristics under isothermal test conditions. Three tubes of different sizes (3, 13, and 20 mm outer diameter) were used in the heat treatments at 57, 60, and 63 degrees C with mashed potato as the test food. A computer model was developed to evaluate the effect of transit heat transfer behavior on microbial inactivation in the test tubes. The results confirmed that the survival curves of E. coli K-12 obtained in 3-mm capillary tubes were log linear at the three tested temperatures. The survival curves observed under nonisothermal conditions in larger tubes were no longer log linear. Slow heat transfer alone could only partially account for the large departures from log-linear behavior. Tests with the same bacterial strain after 5 min of preconditioning at a sublethal temperature of 45 degrees C revealed significantly enhanced heat resistance. Confirmative tests revealed that the increased heat resistance of the test bacterium in the center of the large tubes during the warming-up periods resulted in significantly larger D-values than those obtained with capillary tube methods.     

Polysaccharide additives in foods rich in proteins II. A simple, semi-quantitative technique of estimation (author's transl)]

Samples of foods rich in protein, after removal of lipids and of proteins by enzymatic hydrolysis, are partially demineralized and concentrated. In the concentrate polysaccharides are detected and semi-quantitively estimated by performing the precipitations in graduated tubes, which are especially suitable for this purpose, and the precipitates taken to comparable densities by centrifugation under standard conditions.     

Migration of di(2-ethylhexyl) phthalate from polyvinyl chloride tubes used in preparation of foods

Three samples of polyvinyl chloride products for food use were examined for di(2-ethylhexyl) phthalate (DEHP) migration levels under the conditions described in the Japanese Food Sanitation Law. These samples were two kinds of tubes and one stretched film, containing 12 to 41% DEHP by weight. DEHP migration levels from them were very low, all below 0.1 ppm, into 3 kinds of food simulant; water, 4% acetic acid and 20% ethanol. However, high levels of DEHP migrated into n-heptane, 12 ppm from the stretched film sample and more than 800 ppm from the tube samples. Migration from the 2 tubes was higher than 150 ppm, the limit of residues after evaporation in containers and wraps. Though the limit of residues after evaporation is not set for equipment used in the preparation of foods, the tested tubes were considered to be unsuitable for uses in which they come into direct contact with oils, fats or oily foods.     

食品机械基础件安全卫生标准的要求和分析

介绍了不锈钢钢管、管件、阀门等食品机械基础件类产品的安全卫生标准,根据国际标准要求和国内外应用情况,分析说明有关影响因素。     

Theoretical investigation of fructose 1,6-diphosphate production and simultaneous ATP regeneration by conjugated enzymes in an ultrafiltration hollow-fiber reactor

The performance of an ultrafiltration hollow-fiber reactor, in which enzymatic synthesis of fructose 1,6-diphosphate (FDP) from glucose and enzymatic ATP regeneration are performed simultaneously, was analyzed theoretically. The reaction system consists of three-step synthetic reactions catalyzed by glucokinase (GK), phosphoglucose isomerase and phosphofructokinase, and the ATP regeneration reaction catalyzed by acetate kinase. Based on a simple analytical model developed previously in which the liquid flowing in a tube was assumed to be plug flow and the radial concentration gradients in the tubes and shell side space were both neglected, a computer program was developed to calculate the concentration profiles of all the components along the flow direction in the tubes and shell side space of the reactor. From the FDP concentrations at the reactor outlet calculated under various operational conditions, reactor performances such as the FDP yield and the ATP recycle number were determined. The calculation showed the interesting phenomenon that under some conditions the FDP yield was higher when GK concentration was lower.     

A METHOD FOR TESTING THE EASE OF EXTRUSION OF ICING MARKETED IN PLASTIC TUBES1

An instrumental method for evaluating the ease of extrusion of a decorative cake icing marketed in plastic tubes is demonstrated. The force is measured to pull the tube between two rollers to extrude the contents through the tube nozzle or, by increasing the gap between the rollers, to back extrude the contents within the tube. The maximum force, used as a textural indexy correlated with sensory assessments. The instrumental readings were affected by sample temperature, deformation rate and nozzle size and shape so that these conditions must be standardized. The method has potential use in testing a variety of products marketed in tubes.     

智能纱管应用体会

为提升纺纱质量,介绍智能纱管的性能优势、探索其应用技术,从纺纱车间夜班、白班运转情况详述车间应用智能纱管的操作要点,以及对质量排查问题的处理措施。生产实践表明,应用智能纱管后,疵品纱显著减少、二等品纱由原来的0.08%降低到0.04%;细纱机和纺纱器材制造企业应积极研发自动化、智能化纺纱设备和器材,纺企积极引进并做好应用和管理,才能提升纺纱质量和市场竞争力。     

Bovine lactoferrin and lactoferricin on plasma-deposited coating against spoilage Pseudomonas spp.

Bovine lactoferrin and lactoferricin B, well-known for their antimicrobial properties, were individually immobilized on two different coatings functionalized with − COOH groups deposited in the inner part of polyethylene micro tubes by means of a plasma deposition (PE-CVD) process fed with ethylene and acrylic acid vapors. The resulting functionalized tubes were tested for antimicrobial activity against three Pseudomonas strains responsible for casein hydrolysis and cheese pigmentation. The cell counts of these spoilage bacteria, incubated for 30 h under their optimal growth conditions, were found to be significantly reduced after 24 h in micro tubes functionalized with lactoferricin B, whereas a very low antimicrobial activity against the same strains, often undistinguishable from that of control samples, was observed in tubes functionalized with lactoferrin.This is the first work in which a plasma coating functionalized by lactoferricin B was studied to make an active packaging useful to control cheese spoilage by Pseudomonas.Industrial relevanceThe current study describes a new method to immobilize two food grade proteinaceous natural compounds. The resulting plasma-functionalized lactoferricin B-immobilized coating is a promising tool for the control of spoilage microorganisms and shelf-life extension of cheeses.     

Alternatives to pilot plant experiments in cheese-ripening studies

Experimental studies on cheese have several objectives, from assessing the influence of the microflora and enzymes indigenous to milk to evaluating starters and adjuncts. Several studies have been undertaken to evaluate the influence of an individual ripening agent in the complex environment of cheese. Cheesemaking experiments, even on a pilot scale, are expensive and time-consuming, and when controlled bacteriological conditions are needed, pilot plant experiments are difficult to perform. Cheese curd slurries are simple models that can be prepared under sterile conditions in the laboratory and can be used as an intermediate between test tubes and cheese trials, but probably cannot replace the latter. Miniature model cheeses are similar to pilot plant cheeses and can be manufactured under sterile conditions. Several approaches to assess the role of cheese-ripening agents are reviewed in this paper.