一种针对区间型数据的新主成分分析法

为了减少数据信息的损失,采用推迟区间型数据转换为数值型数据的方法,提出一种针对区间型数据的新的主成分分析方法.它和已有方法的区别在于协方差矩阵和相关矩阵的元素是区间数(从而相关的特征值和特征向量的元素也是区间数).最后用实例验证了该方法的优越性.     

基于模糊系数的投资组合选择模型

组合证券的期望收益率用区间数来描述,风险损失率用梯形模糊数来描述,由此提出组合证券投资的模糊线性规划模型.通过引入模糊数可能性均值的概念,以及区间数线性规划问题中的目标函数优化水平参数η,将目标函数和约束条件分别为区间数和梯形模糊数的模糊线性规划模型转化为普通的线性规划模型,进而求得模型的满意解.     

近红外光谱结合不同偏最小二乘法无损检测食醋中总酸含量

探讨了快速、无损检测食醋中总酸含量的建模方法,利用近红外光谱法分别结合间隔偏最小二乘法(iPLS)、反向区间偏最小二乘法(BiPLS)、联合间隔偏最小二乘算法(SiPLS)进行建模,对各算法在不同划分区间数及区间选择时对建立模型的影响进行比较.结果表明:BiPLS、SiPLS(2,3,4区间联合)建模效果较好于iPLS所建立的模型,其中BiPLS在选择43个子区间,5个子区间联合(3,4,6,7,16)最佳,其RMSECV和RMSEP分别为0.2876和0.2726,校正集和预测集相关系数分别为0.9343和0.938;SiPLS在选择3个区间联合,49个区间数(3、5、7区间联合)最佳,其RMSECV和RMSEP分别为0.2607和0.2802,校正集和预测集相关系数分别为0.9463和0.9371;iPLS在选择22个子区间,第三个子区间,主因子数为4时最佳,其RMSECV和RMSEP分别为0.2998和0.2977,校正集和预测集相关系数分别为0.928和0.9213.不同偏最小二乘算法所选取区域大多集中于5500～6000 cm-1范围内,证明该波数范围应该是总酸的相应特征区间.     

关于区间数绝对值运算的几个结果

新定义了区间数的一种绝对值运算。根据已有的区间数绝对值运算,进一步研究了区间数的绝对值运算以及区间数的中心的性质。同时根据实数的运算法则原理,将数的四则运算推广至区间数,讨论了区间数所满足的四则运算。由于区间数在表示和处理不确定性问题中具有重要意义,本文借助所定义的区间数的绝对值运算定义了区间数之间的距离。     

一种基于OWA算子的区间值模糊推理方法

提出了一种基于区间值模糊集近差的双阈值多重多维模糊推理方法.通过基于组合数的OWA算子赋权方法计算出区间值模糊规则前件的各个权值,并且在计算区间值模糊集近差的时候,考虑区间值的上限和下限对计算近差的影响程度不同,以及论域中各因素或属性对于结论的重要性不尽相同的情况,从而过滤掉一些不必要的规则.算例分析表明,该方法更接近实际推理,结果便于应用.     

基于区间层次分析法的食品安全网络舆情预警评价

针对食品安全网络舆情预警评价问题的不确定性,提出了一种新的食品安全网络舆情预警评价方法。建立了多层次的食品安全网络舆情预警评价指标体系,提出了食品安全网络舆情预警等级和区间数等级,利用区间层次分析法确定了食品安全网络舆情预警评价指标的区间数权重。结合区间数理论构建了基于区间层次分析法的食品安全网络舆情预警评价模型。结合评价实例对某食品安全事件的网络舆情预警等级进行了评价,验证了该综合评价模型的合理性和有效性。     

单张纸胶印机印张前深后淡及中间不平整分析

1.印张状况某型单张纸胶印机在进行实地满版印刷中,以咬口白过为始,0-150mm左右区间墨色较深;150-200mm左右区间墨色较淡且不平整,时有软墨杠,约3～4条;220mm以后区间,墨色较淡且平整。在进行网线满版印刷时也时有前部分深后部分淡现象,严重时,产生阴阳版,分界面在150—220mm间。2、印机几项参数2.1原始数据印版滚筒直径（加包村）：小250．4mm;印版滚筒缺口角度：100o串墨辊根数：4着墨辊根数：4匀墨辊根数：92．2扩展数据印版滚筒缺口弧长L—100／7t180x125．2。218．5四根着墨辊周长如表一。四根着辊在印版滚筒缺口部位能转…     

一个连续型不确定集结算子及其在多属性决策中的应用

将连续区间有序加权平均（C-OWA）算子与广义平均算子相结合,提出了一个连续型不确定的集结算子,广义连续区间数据有序加权平均（GC-OWA）算子.给出了基于此算子的不确定多属性决策方法,最后的实例说明方法的有效性和合理性.     

樱桃多品质数据分析与无损快速检测模型的建立

目的 研究樱桃多品质数据分布情况, 建立樱桃多品质无损快速检测方法。方法 对樱桃样品分别测试可溶性固形物含量、可滴定酸含量、果实硬度。采用统计分析方法对数据进行统计学描述, 分别绘制含量分布直方图并计算直方图分布频次百分比。以樱桃样品近红外光谱数据为自变量、品质数据参考值为因变量建立樱桃品质无损快速定量检测模型。结果 统计分析结果表明, 可溶性固形物含量11~17 Brix区间范围内的样品数占样品总数的约86.0%, 可滴定酸含量0.1%~0.8%区间范围内的样品数占样品总数的约90.4%, 果实硬度1.60~3.00 kg/cm2区间范围内的样品数占样品总数的约86.0%。多元回归建模结果表明, 剔除异常值有助于提高模型预测性能, 剔除异常值后可溶性固形物含量、可滴定酸含量、果实硬度模型的相对预测性能值分别提高了15.3%、32.9%、12.3%。结论 采用统计分析结合直方图分析可较直观地描述樱桃品质分布情况; 剔除异常值对提高樱桃可滴定酸含量近红外无损检测模型预测能力的作用最大。     

氨基硅油分子质量的测定

以α,ω-二羟基聚二甲基硅氧烷和N-哌嗪基丙基甲基二甲氧基硅烷为原料,在碱性催化剂存在的条件下合成哌嗪型氨基硅油.运用理论分子质量的方法即通过改变催化剂用量来控制氨基硅油的分子质量.利用1H-NMR跟踪进行定量和定性分析,确定反应是否完全.采用单点法和外推法测出特性粘数[η],并将哌嗪型氨基硅油理论分子质量与所测得的特性粘数数据进行处理,得出相应的MHS方程参数α和K,由此得到了适合哌嗪型结构氨基硅油的MHS方程.     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.