基于BP神经网络的机采原棉品质指标预测模型

为了对脱籽后的机采原棉品质指标进行预测并实现优化控制,设计了用于机采原棉品质指标预测的BP神经网络模型。以南疆地区机采棉为研究对象,以影响原棉品质的主控因素籽棉回潮率和轧花速度为BP神经网络模型的基本特征量,建立了机采原棉品质指标的BP神经网络预测模型。结果表明:该BP神经网络模型能较好表达机采原棉各品质指标与主控因素之间的非线性关系,预测结果与实测值之间误差小,测试样本的网络输出值与网络目标值的相关系数均接近1,模型预测效果较佳。认为:该BP神经网络模型可作为机采原棉品质预测与调控的新方法,也可应用于机采籽棉轧花在线原棉品质监控。     

基于模拟退火遗传算法优化的BP网络在质量预测中的应用

翘曲量预测精度是注塑成形优化的难点。文章以某零件翘曲量为对象,选取注射温度、模具温度、保压压力、保压时间、注射速度等参数,进行数值模拟实验,建立BP神经网络的翘曲量预测模型。针对BP神经网络易陷入局部最优解的缺陷,设计一种基于模拟退火遗传算法优化的BP网络模型,与BP网络的预测精度对比。结果表明,基于模拟退火遗传算法优化的BP网络模型预测精度高于BP网络模型,同时加快收敛速度,增强全局搜索能力。     

基于免疫遗传算法的BP神经网络在纱线条干预测上的应用

为了避免因随机生成BP神经网络初始权值和阈值而带来的不确定性,以及得到更好的预测纱线条干CV值的精度和速度,借助免疫遗传算法对传统单一的BP神经网络进行权值和阈值的优化。免疫算法中特有的浓度调节机制有效地解决了遗传算法后期未成熟收敛的问题。利用Matlab构建单一的BP神经网络模型、遗传BP神经网络模型和免疫遗传BP神经网络模型进行纱线条干CV值的预测实验,通过仿真训练结果的对比分析可得出,免疫遗传算法优化的BP神经网络能够更准确、更快速、更稳定地完成纱线条干CV值的预测。     

原棉性能与成纱质量的WEKA-人工神经网络预测

采用WEKA特征选择法分析了原棉的性能指标对成纱质量的影响,并结合BP人工神经网络对成纱条干、成纱强度和成纱强度不匀进行了预测。采用WEKA特征选择法可以减少BP神经网络的输入节点数,与单纯的BP神经网络的预测结果相比,WEKA特征选择法结合BP神经网络预测结果较准确,预测值与实测值之间的平均相对误差较小。     

棉花性能指标对成纱质量的预测模型研究

探讨基于遗传算法和主成分分析法与BP神经网络相结合的棉花性能指标对成纱质量的预测模型。分别采用单一BP神经网络(模型1)、主成分分析加BP神经网络(模型2)、主成分分析加遗传算法优化隐层节点数后的BP神经网络(模型3),依据实测原棉数据对成纱品质作预报,并以平均相对误差百分率指标最小为原则,对比了三种模型的优劣。结果表明:模型3的平均相对误差百分率值最小;主成分分析表面上在降维,但对神经网络来说仍是高维的计算,最优结果的隐层节点数均高于经验公式确定的隐层节点数,接近于13个原始变量数。认为:基于遗传算法和主成分分析法与BP神经网络相结合进行预报,能够使预测精度得到明显提高。     

不同拓扑结构原棉品质指标预测模型的预测效果对比

采用BP神经网络预测手摘籽棉脱籽后原棉的多个品质指标。以南疆库尔勒地区某轧花厂为试验场,选择籽棉回潮率、轧花速度和喂花量3个关键因素作为输入层自变量,建立手摘籽棉的3个轧花品质指标(UHML、Str、SF)预测模型。试验结果表明:3-3-2-2-3网络拓扑结构的BP神经网络模型能较好表达轧花原棉3个品质指标与关键因素之间的复杂关系,轧花品质指标预测模型的预测输出值与试验目标值的相关系数接近0.984 1,BP神经网络模型可实现籽棉多个轧花品质指标的有效预测。     

基于思维进化神经网络的细纱断裂强度预测

探讨一种基于思维进化算法优化BP神经网络的细纱断裂强度预测方法。利用思维进化算法对BP神经网络的阈值和权值进行优化,发挥在全局寻优方面的优势。试验结果表明:基于思维进化算法优化BP神经网络预测模型比单一的BP神经网络预测模型具有更高的准确性,该模型的细纱断裂强度预测值与实测值之间的平均绝对百分比误差和均方根误差下降明显。认为:基于思维进化算法优化BP神经网络模型具有更好的综合预测性能。     

提高3C钢腐蚀速度预测准确度的方法研究

针对BP神经网络模型对3C钢腐蚀速度的预测存在精度低问题,建立了基于遗传算法的3C钢神经网络预测模型。该模型采用遗传算法优化BP神经网络的初始权值和阈值。实例对比分析表明:采用遗传神经网络预测3C钢的腐蚀速度,提高了准确率,具有应用可行性。     

基于人工神经网络的纱线断裂伸长预测

使用HVI测试原棉指标和USTER TENSOJET 4测试成纱指标.分别用标准BP、LMBP算法建立断裂伸长预测的神经网络模型,进行纱线的断裂伸长预测,结果表明LMBP算法建立的模型预测速度和精度明显高于标准的BP算法.     

BP神经网络优化Stearns-Noechel模型的羊毛色纺纱配色

为了提升羊毛色纺纱配色的精确度,通过数理统计方法研究颜色特征中的色相、明度、饱和度与Stearns-Noechel模型参数M值之间的关系,采用BP神经网络对Stearns-Noechel模型参数M值进行优化,并与传统的最优平均M值和波长优化M值等方法进行对比。结果表明：采用BP神经网络优化Stearns-Noechel模型的配色方法比其他2种传统优化方法在颜色预测精确度上都有提高。在99个羊毛混色纱试验样本中,BP神经网络优化方法得到的平均色差最小,为1.177 3,其中色差小于1的样本占54%,结合颜色特征采用BP神经网络优化的Stearns-Noechel模型参数具有较好的效果,对羊毛色纺纱的颜色预测精确度有较大的提高。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.