课程文献中心 更多>>

关键词： honey   botanical origin   front face fluorescence spectroscopy   chemometric   AMINO-ACID-COMPOSITION   GEOGRAPHIC ORIGIN   FLORAL ORIGIN   INFRARED-SPECTROSCOPY   PHENOLIC-COMPOUNDS   ELECTRONIC NOSE   CLASSIFICATION   CHEESES   FLAVOR   IDENTIFICATION  

摘要： This study reports the use of front face fluorescence spectroscopy as a tool for the classification of honey samples from Switzerland according to their botanical origins. Honey (n = 62) fluorescence spectra from seven floral origins, namely, acacia, alpine rose, chestnut, rape, honeydew, alpine polyfloral and lowland polyfloral were scanned after excitation set at 250 nm (emission: 280-480 nm), 290 nm (emission: 305-500 nm) and 373 nm (emission: 380-600 nm) and emission set at 450 nm (excitation: 290-440 nm). The first 10 principal components (PCs) of the principal component analysis (PCA) extracted from each data set were gathered together into one matrix and analysed by factorial discriminant analysis (FDA). Correct classification of 100% and 90% was observed for the calibration and the validation samples, respectively. The seven honey types were well discriminated indicating that the molecular environment and, for consequent, the physico-chemical properties of the investigated honeys were different. The obtained results showed that front face fluorescence spectroscopy might be a suitable and alternative technique to classify honey samples according to their botanical origins. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： REGRESSION analysis   CURRENCY crises   MONEY market funds -- Reserves   ECONOMICS   CAPITALISM   FOREIGN exchange  

摘要： This article tackles the issue of reserve adequacy measure by examining the interaction of high reserves and weak fundamentals in crises. The author extends the analysis of Sachs et al. (1996) by adopting on two-step regressions. The first helps find the significant weak fundamental variables. The second determines the appropriate adequate reserve level.

关键词： 模式识别   气体传感   人工电子鼻  

摘要： 人工电子鼻系统能够代替人类的嗅觉对气味进行识别,它可以代替人类在危险环境中执行气味识别任务,可以对食品品质进行评估,也可以将其运用在国家安全领域,如防止恐怖分子进行炸弹袭击。人工电子鼻系统是当前仿生学研究的一个方向。 本文对人工电子鼻系统中的模式识别方法进行研究。文中使用商用气体传感器搭建测试平台,采集数据后对其进行模式识别分析,主要的研究工作如下: 1.使用5个Figaro公司生产的不同型号的气体传感器构成阵列,将气体传感器的电导信号变化转换为电压信号变化;2.在LabVIEW中自行设计数据采集程序,配合PCI-6251数据采集卡对气体传感器调理电路中参考电阻上输出的电压信号变化量进行采集,将获得的数据存储为Excel能够读取的lvm文件;3.气体样本采集实验中对丙酮样品和乙醛样品（A组）的挥发性气体各进行150次实验,获得300组实验数据;此外自行配制体积比均为31%的甲醇溶液和二锅头溶液（B组）,对它们的挥发气体进行100次数据采集;4.为了降低数据维数,避免“维数灾难”,对所有实验数据进行特征数据提取,从每次实验1,500个数据点中提取出25个特征点来表征一种气体样品,并将结果提供给模式识别算法进行分类实验;5.总体分析三大类模式识别方法的基本原理。从中选取三种方法:线性判别函数法、聚类分析法和BP神经网络法,进一步分析这三种方法的计算原理和步骤。将这三种方法分别运用到A组和B组的分类实验中,其中BP神经网络法还使用多种训练函数,讨论不同训练算法对训练速度和对未知样本分类效果的影响,最终得出结论:三种方法对前一组样品能够正确分类,对后一组样品无法正确分类;6.对三种模式识别方法的优劣进行分析和对比,得出结论:在数据维数低的情况下,线性判别函数法和聚类分析法能够快速地分类,因为其算法简单,但是当维数增加时,由于线性判别函数法需要对矩阵求逆,聚类分析法如果选择较为复杂的相似性测度函数,二者的计算量会增加,致其不再具备快速简便的优点;BP神经网络具有高度的非线性,在理论上能够接近任意曲面,但是计算过程复杂,计算量大,不容易用程序代码实现。本文实验最合适的方法是聚类分析法。本文的主要特色: 1.自行设计数据采集软件,可以实时观测测量过程中参考电阻输出电压随气体浓度变化的曲线,在将采集获得的数据导入Excel后,可以清晰绘制不同气体样品的“图谱”;2.设计半开放的实验气室,充分利用气体样品的动态信息,为识别增加信息量,同时也加快实验的速度;3.特征数据提取过程完全自动化,无需过多的人工参与,特征提取代码采用模块化设计,Excel只作为数据显示和输入的用户接口,所有计算任务均由Matlab完成,并且在计算代码中也遵循模块化设计,将实现复杂功能的代码作为函数写入代码;4.提出遗传算法对线性判别函数法中分界点进行优化的思想。

关键词： atherosclerosis   partial least squares data analysis   principal components regression   Mahalanobis distance   infrared reflectance microscopy   attenuated total reflectance infrared spectroscopy   LASER-INDUCED FLUORESCENCE   TRANSFORM RAMAN-SPECTROSCOPY   ATTENUATED TOTAL REFLECTANCE   FT-IR MICROSPECTROSCOPY   HUMAN ARTERY   INFRARED-SPECTRA   HUMAN TISSUE   PLAQUE   VIVO   CHOLESTEROL  

摘要： Atherosclerotic and normal rabbit aorta samples show a marked difference in chemical composition governed by the water, lipid, and protein content. The strongly overlapping infrared absorption features of the different constituents, and the complexity of the tissue matrix, render tissue classification by direct evaluation of molecular spectroscopic characteristics obtained from IR reflectance or attenuated total reflectance (ATR) measurements virtually impossible. We apply multivariate analysis and classification techniques based on partial least squares regression (PLS) and linear discriminant analysis to IR spectroscopic data obtained by IR-ATR measurements and reflectance IR microscopy with high predictive accuracy during blind testing. Training data are collected from atherosclerotic and normal rabbit aorta samples. These results demonstrate the potential of IR spectroscopy combined with multivariate classification strategies for the in-vitro identification of normal and atherosclerotic aorta tissue. The prospect for future in-vivo measurement concepts is also discussed. (C) 2007 Society of Photo-Optical Instrumentation Engineers.

关键词： 票据法律关系   涉外票据   涉外票据特征  

摘要： 伴随着科学技术的进步,国际间经济关系的日益密切,各固人民交往的频繁和资本的日益固际化,票据关系也越来越多地具有了国际性。因此,从国际私法的角度来讨论涉外票据关系问题显得日益重要。只有首先解决这些问题,才能够正确的认识涉外票据,进而正确定位其独特的法律适用规则。

关键词： 电子商务   电子合同   成立时间  

摘要： 随着近年来电子商务的迅猛发展,电子合同作为一种新的商业活动形式,得到极为广泛的应用。由于电子合同与传统合同的极大不同,引发了诸多新的法律问题。本文拟从电子合同成立时间的确定方面做一些初步探讨。

关键词： 市场采购出口货物   检验检疫   标准化   技术规范  

摘要： 随着我国玩具市场的多元化,玩具产品的花样出新,到我国进行市场采购玩具出口的国际商人也日益增多。然而一些经销商片面追求利润,没有选择性地采购实施国家规定的强制性产品认证的玩具,在降低成本的同时也降低了质量,使在市场上采购的出口玩具存在越来越多的质量隐患;这使得这些打上"中国制造"标签的玩具在国际市场上声名狼藉,严重损害中国在国际上的形象和地位。检验检疫部门应当利用其行政执法部门的优势地位,充分发挥积极有效的监管作用,做好为中国对外贸易企业的服务工作,推动我国各类产品的顺利出口,维护国家和人民的利益。

关键词： purge & trap   GC-MS   pine honey   KSOM   FLORAL ORIGIN MARKERS   GC-MS   STRAWBERRY AROMA   DISCRIMINATION   VARIETIES   CHESTNUT   QUALITY   FLAVOR  

摘要： Forty-four samples of pine honey were analysed, 22 from Greece and 22 from Turkey. A purge & trap-gas chromatograph-mass spectrometer system was used for the extraction, separation and identification of volatile, and semi-volatile compounds. In all, 77 compounds were extracted and identified. Two of them, the 3-carene, and one unidentified compound (m/z 55, 79, 91, 107, 123, 165) were found to be specific to Turkish honeys and may be considered as markers characterising the Turkish origin of samples. Beyond this result, and by using the Kohonen self-organizing map (KSOM), a clear differentiation was obtained between the Turkish and Greek pine honey samples from a global consideration of all the analysed volatile constituents. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： 进出口   价格核算   国际贸易实务   综合实验   学生   实践能力   增强   课程   技能  

摘要： <进出口价格核算综合实验>是<国际贸易实务>课程中一个重要的内容,它对于增强学生的实践能力,提高学生进出口价格核算的技能具有现实意义.

关键词： 质押合同   债权合同   诺成合同   不要式合同  

摘要： 质权作为一种重要的担保物权,在现实的经济生活中发挥着重要的作用。质押合同是质权设定的要件,其性质和形式关乎质权的成立生效,但是由于我国《担保法》规定的某些缺陷,让人们对质权的设定要件产生误解,尤其是对质权设定的核心要件质押合同存在较多的误解。因此,以《担保法》的规定为基础,探讨质押合同的性质和形式,无疑具有重要的意义。