动态称重系统的动态补偿和校正

针对动态称重系统中的系统数学模型时变非线性强、传感器动态品质差、留空量和冲击力难以确定等一些造成称重系统快速性和精度难以提高的因素，提出了一种改善动态称重系统性能、提高测量精度的新方法。该方法通过在传感器后串联补偿环节对传感器进行动态补偿，同时，根据前几次称重误差在称重系统中引入具有仿人智能控制思想的模糊控制器。下料实验表明：采用上述方法后，动态称重系统的绝对误差小于25g，计量精度小于2．5‰FS，有效地提高了动态称重系统的快速性和精度。     

基于RBF神经网络的纸张定量水分解耦控制系统设计

抄纸过程中纸机系统具有大滞后、非线性、时变等特点,纸张定量与水分之间存在强耦合效应,针对这些问题,设计了一种基于RBF神经网络的PID解耦控制方法.利用RBF神经网络辨识定量与水分的数学模型,实时调整PID控制器的参数,实现系统的解耦功能.仿真结果表明,该方法具有良好的静态、动态性能和很强的自适应性,能有效解决纸张定量和水分之间的耦合作用.     

包装生产线电子秤动态称重性能分析与改进

为了改进旧包装生产线电子秤的动态称重性能,根据动态称重系统中的数学模型时变非线性强、传感器动态品质差以及被测对象冲力、秤体振动、空中余料难以确定等一些造成称重系统快速性和精度难以提高的因素,提出了零极点配置的自适应动态补偿和基于哈明窗的FIR低通滤波方法,实际应用表明:本方法能有效地改善称重精度,缩短信号衰减时间,提高称重速度。     

基于模糊神经网络PID控制的粉体包装计量控制系统

针对粉体包装计量控制系统由于传感器、螺杆的旋转惯性、零点漂移,下料冲击力等因素的影响而造成的系统延迟、非线性等问题,提出一种基于模糊神经网络PID控制粉体包装计量控制系统。利用模糊神经网络良好的动态控制特性和自学习能力来调整PID控制比例、积分、微分3个调整参数。借助MATLAB simulink仿真软件进行系统的模拟仿真。结果表明,该模糊神经网络PID控制系统稳定时间能缩短约45%,超调量约减少16%。由此可得模糊神经网络PID控制系统优于传统的PID控制系统。     

食品定量称重包装控制系统设计

为提高食品称重包装工艺效率、提升食品称重精度、降低工人劳动强度,设计一款基于PLC的食品定量称重控制系统。介绍食品称重控制系统总体结构,并分析实现精确称重的控制过程,在此基础上设计控制系统硬件。以威纶触摸屏为上位机设计人机画面,直接采集称重系统数据并实现系统全程监控,有效提高称重包装系统的可靠性和可视性。该控制系统能够显著提高称重包装效率,提升称重包装精度。     

基于BP神经网络算法的食品烘干机温度控制

以自动链板式茶叶烘干机为研究对象,为降低燃煤热风炉能耗、提高热效率、提高烘干机温度控制精度,提升茶叶品质,提出了一种基于改进BP神经网络的控制策略。分析了烘干机的结构和控制原理,在此基础上将BP神经网络与PID控制方法相结合,通过神经网络的自学习、加权系数的调整,优化PID控制器参数K_i、K_p、K_d,并将粒子群算法引入到神经网络中作为其学习算法,以有效提高BP神经网络算法的收敛速度。仿真结果表明,该控制方法响应速度快,超调量小,从而实现对热风温度的恒温控制。     

改进模糊PID的称重式包装机智能控制

针对称重式包装机称重控制系统存在非线性、时变、时滞的特性,导致称重精度低、稳定性差的问题,在传统模糊PID控制算法的基础上,引入模糊变量论域伸缩因子,提出域伸一种改进模糊PID算法。设计变量论缩因子使模糊变量论域跟随称重误差及误差率的变化而伸缩调整,将模糊变量论域调整为最佳范围,以避免因变量论域不恰当而引起的控制误差。利用改进模糊控制算法对PID参数进行在线整定,以实现称重控制系统高效、精确、稳定的控制效果。仿真结果表明改进模糊PID控制算法具有超调量小、响应速度快、抗干扰能力强的优点,该控制算法能够有效提升包装机称重效率和称重精度。     

定量电子包装秤中关键误差解决方案

通过建立称重数学模型,分析在动态称重过程中产生误差的原因,并结合动态系统对称重速率和称重精度的整体要求,在国内外现有技术的基础上,提出了一套基于三料速时序控制和数字增量式PID算法的系统关键性误差解决方案。详细阐述了三料速时序控制流程以及各参数的设定办法,并对数字增量式PID算法进行了推导和对参数设定进行了讨论,给出了该算法动态校正的程序流程。     

称重式自动油墨灌装机的研究与设计

阐述了一种高精度的称重式自动油墨灌装机的设计方法,通过从理论上对油墨灌装过程进行分析,提出了有效提高油墨灌装精度的方法,并应用PID控制技术控制灌装压力和称重平台的下降速度,同时增加了灌装的自动纠偏功能,有效改善了"飞料误差"对油墨灌装精度产生的影响。     

提高定量包装称重精度的措施

动态称重包装在化工、饲料等行业有广阔的应用 ,本文从讨论饲料称重包装中的应用入手 ,给出了提高动态称重精度的思路和方法 ,并已经在饲料动态称重包装中得到了应用     

ICP/MS and ICP/AES elemental analysis (38 elements) of edible wild mushrooms growing in Poland

Thirty-eight elements, including toxic cadmium, lead, mercury, silver and thallium, were determined in 18 species of wild edible mushrooms collected from several sites in Pomorskie Voivodeship in northern Poland in 1994. Elements were determined by double focused high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), after wet digestion of the dried samples with concentrated nitric acid in closed PTFE vessels using a microwave oven. K, P and Mg were present at levels of mg/g dry matter; Na, Zn, Ca, Fe, Cu, Mn, Rb, Ag, Cd, Hg, Pb, Cs, Sr, Al and Si were present at µg/g levels, while Tl, In, Bi, Th, U, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, La, Lu and Ba were present at ng/g levels.     

蒽醌助剂对乙二醇溶剂脱胶苎麻纤维性能的影响

为解决苎麻在乙二醇有机溶剂脱胶中纤维易被氧化而导致性能下降的问题,在乙二醇溶剂中添加助剂蒽醌对苎麻进行脱胶,并对蒽醌不同添加量下制得的纤维进行结构和性能表征。结果表明:纤维中半纤维素含量随蒽醌添加量的增加而升高,纤维的聚合度、结晶度、物理力学性能先升高后降低,纤维的残胶率和线密度先降低后升高;当蒽醌质量分数为0.3% 时,这些性能均达到最佳值,此时纤维的聚合度、结晶度、制成率、断裂强度、断裂伸长率、断裂功比不加蒽醌时分别提高了7.32%、20.53%、1.46%、9.55%、6.89%、33.33%,纤维的残胶率、线密度比不加蒽醌时分别降低了17.91%、7.24%。     

Encapsulation of food ingredients

Microencapsulation is a relatively new technology that is used for protection, stabilization, and slow release of food ingredients. The encapsulating or wall materials used generally consist of starch, starch derivatives, proteins, gums, lipids, or any combination of them. Methods of encapsulation of food ingredients include spraydrying, freeze‐drying, fluidized bed‐coating, extrusion, cocrystallization, molecular inclusion, and coacervation. This paper reviews techniques for preparation of microencapsulated food ingredients and choices of coating material. Characterization of microcapsules, mechanisms of controlled release, and efficiency of protection/ stabilization of encapsulated food ingredients are also presented.     

Daily intake of trace metals through coffee consumption in India

The trace element contents of five varieties of instant coffee powder available in the Indian market have been analysed. Ca, Cr, Fe, K, Mg, Mn, Ni, Sr, Zn and Pb, Cd, Cu have been determined using atomic absorption spectrophotometry and differential pulse anodic stripping voltammetry, respectively. The metal levels in the coffee powders observed in this study are comparable with those reported for green coffee beans (Arabica and Robusta variety) reported worldwide with the exception of Sr and Zn, which were on the lower side of the reported values. Concentrations of these metals have been converted into intake figures based on coffee consumption. The daily intakes of the above metals through ingestion of coffee are 1.4mg, 1.58 mu g, 124 mu g, 41.5mg, 4.9mg, 17.9 mu g, 2.9 mu g, 3.8 mu g, 12.5 mu g, 0.2 mu g, 0.03 mu g and 15.5 mu g, respectively. The values, which were compared with the total dietary intake of metals through ingestion by the Mumbai population, indicate that the contribution from coffee is less than or around 1% for most of the elements except for Cr and Ni which are around 3% .     

Avena sativa (Oat), A Potential Neutraceutical and Therapeutic Agent: An Overview

The aim of the present review article is to summarize the available information related to the availability, production, chemical composition, pharmacological activity, and traditional uses of Avena sativa to highlight its potential to contribute to human health. Oats are now cultivated worldwide and form an important dietary staple for the people in number of countries. Several varieties of oats are available. It is a rich source of protein, contains a number of important minerals, lipids, β-glucan, a mixed-linkage polysaccharide, which forms an important part of oat dietary fiber, and also contains various other phytoconstituents like avenanthramides, an indole alkaloid-gramine, flavonoids, flavonolignans, triterpenoid saponins, sterols, and tocols. Traditionally oats have been in use since long and are considered as stimulant, antispasmodic, antitumor, diuretic, and neurotonic. Oat possesses different pharmacological activities like antioxidant, anti-inflammatory, wound healing, immunomodulatory, antidiabetic, anticholesterolaemic, etc. A wide spectrum of biological activities indicates that oat is a potential therapeutic agent.     

5—THE CONSTITUTION OF THE EPICUTICLE OF WOOL

Epicuticle, isolated from wool via the Allwörden reaction, was examined by electron microscopy and analysed chemically. It is proteinaceous; lipids and carbohydrates could not be detected. The component amino acids are: cystine, glycine, glutamic acid, serine, valine, alanine, lysine, α-amino-adipic acid, and threonine. A tentative model for the epicuticle is proposed.     

Matrix effects on flavour volatiles release in dark chocolates varying in particle size distribution and fat content using GC–mass spectrometry and GC–olfactometry

Influences of matrix particle size distribution (PSD) (18, 25, 35 and 50 μm) and fat content (25%, 30% and 35%) on flavour release of dark chocolate volatiles were quantified by static headspace gas chromatography using GC–MS. Sixty-eight (68) flavour compounds were identified, comprising alcohols, aldehydes, esters, ketones, furans, pyrans, pyrazines, pyridines, pyroles, phenols, pyrones and thiozoles. From GC–olfactometry, 2-methylpropanal, 2-methylbutanal and 3-methylbutanal had chocolate notes. With cocoa/roasted/nutty notes were trimethyl-, tetramethyl-, 2,3-dimethyl-, 2,5-dimethyl-, 3(or 2),5-dimethyl-2(or 3)-ethyl- and 3,5(or 6)-diethyl-2-methylpyrazine and furfuralpyrrole. Compounds with fruity/floral notes included 3,7-dimethyl-1,6-octadien-3-ol and 5-ethenyltetrahydro-R,R,5-trimethyl-cis-2-furanmethanol. Caramel-like, sweet and honey notes were conferred by 2-phenylethanol, phenylacetaldehyde, 2-phenylethylacetate, 2,3,5-trimethyl-6-ethylpyrazine, 2-carboxaldehyde-1H-pyrrole, furancarboxaldehyde, furfuryl alcohol and 2,5-dimethyl-4-hydroxy-3(2H)furanone. There were direct relationships of fat content with 3-methylbutanal and branched pyrazines but inverse ones with 2-phenylethanol, furfuryl alcohol, methylpyrazine, phenylacetaldehyde, 2, 3, 5-trimethyl-6-ethylpyrazine and 2-carboxaldehyde-1-H-pyrrole. Particle size influenced higher alcohol, aldehyde, ester, ketone and pyrazine concentrations at all fat contents. A multivariate product space suggested flavour effects of the interacting factors.     

Influence of different non-grain commodities on the population growth of Trogoderma granarium Everts (Coleoptera: Dermestidae)

We investigated the population growth of the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) on seven groups of commercially available non-grain commodities. Six powdered spices were used in the first group of experiments: black pepper, clove, nutmeg, allspice, cinnamon and turmeric. The second group of the tested commodities included seven animal products: powdered cow milk, powdered pork zelatin, sheeps’ wool, goat’s skin, ducks’ feathers, dry dog food and dry cat food. The third group of commodities was consisted of six herbs: oregano, spearmint, basil, coriander, laurel and marjoram. The fourth group of commodities contained ten pulses: chickpeas, lentil, split peas, black-eyed peas, beans, soybean flour and whole kernels, lima beans, mung bean, and broad beans. The fifth group comprised six dried fruits: Corinthian currants, sultanas, banana chips, melons, apricots and figs. The sixth group was consisted of five non-grain commodities: cottonseed cake, tobacco, black tea, Turk kahvesi and potato flour. The seventh group included seven nuts: sunflower seeds, pumpkin seeds, pistachios, roasted chickpeas (yellow), almonds, hazelnuts and walnuts. Finally, six cracked containment categories (0% cracked kernels, 5% cracked kernels and 95% intact kernels, 10% cracked kernels and 90% intact kernels, 25% cracked kernels and 75% intact kernels, 50% cracked kernels and 50% intact kernels and 100% cracked kernels) from five pulses were tested: chickpeas, black-eyed peas, mung bean, soybean and split peas. The highest progeny production (3.01 individuals per vial) was recorded on powdered cow milk. On pistachios, split peas, sunflower seeds, soybean flour, pumpkin seeds, walnuts, almonds and coriander, T. granarium built high population densities rapidly, while on roasted chickpeas, cottonseed cake, hazelnuts, chickpeas, dog food and lentils, its population growth was much less. Broad beans, melons, figs, lima beans, beans, Corinthian currants, pork zelatin and potato flour were less suitable diets for the development of this species. On black pepper, clove, nutmeg, allspice, cinnamon, turmeric, sheeps’ wool, goat’s skin, ducks’ feathers, cat food, sultanas, banana chips, apricots, tobacco, black tea, Turk kahvesi, oregano, spearmint, basil, laurel and marjoram, no progeny production was recorded. The proportion of 100% cracked black-eyed peas or mung beans was more suitable for the population growth of T. granarium. Also, the percentages of 50% cracked chickpeas or 10% cracked soybeans enhanced the development of the species, in comparison with the whole kernels of each pulse. Our study indicated that several non-grain commodities are beneficial for the population growth of T. granarium, a fact that should be seriously taken into account in international trade, as this pest may utilize them as “vehicles” of expansion.     

Bioactivation of Phytoestrogens: Intestinal Bacteria and Health

Phytoestrogens are polyphenols similar to human estrogens found in plants or derived from plant precursors. Phytoestrogens are found in high concentration in soya, flaxseed and other seeds, fruits, vegetables, cereals, tea, chocolate, etc. They comprise several classes of chemical compounds (stilbenes, coumestans, isoflavones, ellagitannins, and lignans) which are structurally similar to endogenous estrogens but which can have both estrogenic and antiestrogenic effects. Although epidemiological and experimental evidence indicates that intake of phytoestrogens in foods may be protective against certain chronic diseases, discrepancies have been observed between in vivo and in vitro experiments. The microbial transformations have not been reported so far in stilbenes and coumestans. However, isoflavones, ellagitanins, and lignans are metabolized by intestinal bacteria to produce equol, urolithins, and enterolignans, respectively. Equol, urolithin, and enterolignans are more bioavailable, and have more estrogenic/antiestrogenic and antioxidant activity than their precursors. Moreover, equol, urolithins and enterolignans have anti-inflammatory effects and induce antiproliferative and apoptosis-inducing activities. The transformation of isoflavones, ellagitanins, and lignans by intestinal microbiota is essential to be protective against certain chronic diseases, as cancer, cardiovascular disease, osteoporosis, and menopausal symptoms. Bioavailability, bioactivity, and health effects of dietary phytoestrogens are strongly determined by the intestinal bacteria of each individual.     

Evaluation of mycotoxin-contaminated cereals for their use in animal feeds in Hungary

In the period between December 5, 1991 and September 17, 1998, 760 maize, 367 wheat, 119 soybean, 222 barley, 85 bran, 32 triticale, 60 oat, 14 rye and 22 sunflower samples were investigated for the presence and concentration of seven fusariotoxins (T-2 toxin, zearalenone, deoxynivalenol, nivalenol, diacetoxyscirpenol, HT-2 toxin, fusarenone-X) and OTA. The comparison of analytical data with those of the relevant literature revealed that although the incidence rate and/ or concentration of Fusarium mycotoxins and OTA in Hungarian-grown cereals is occasionally considerable, the position of the country is not worse than the average of countries. Our findings indicate that soybean tends to be good substrate for trichothecene-producing fungi and the rate of contamination is regarded as substantial. The commodities were assorted into one of three quality categories. The proportion of objectionable samples was only 3.0, 2.2, 2.3 and 1.7% in maize, wheat, barley and soybean samples, respectively. However, this low rate of objection might still be a source of great economic loss. The proportion of objectionable samples was much higher in the case of bran, oat and triticale (7.1, 6.7, and 6.3%, respectively). The results of the present investigation indicate a need for regular screening for mycotoxins of importance and individual appraisal of each commodity from the point of their use in animal feeds.