带跳变时滞随机微分方程E-M方法指数稳定性

研究了带跳变时滞随机微分方程Euler-Maruyama方法的指数稳定性.在全局Lipschitz条件及解析解和数值解在均方有界的条件下,证明了SDVDEJs的指数稳定性的充要条件是Eul-er-Maruyama方法下构造的数值解是指数稳定性.避免了寻找Lyapunov函数的困难,将指数稳定性的等价关系推广到带跳变时滞情形.     

带Poisson跳和Markovian转换的随机时滞泛函微分方程数值解的收敛性

为了近一步研究带Poisson跳和Markovian转换的随机时滞泛函微分方程数值解的收敛性问题,文中给出带Poisson跳和 Markovian 转换的随机时滞泛函微分方程 Euler 数值解迭代格式。在弱条件下,利用Laypunov泛函方法和随机分析理论证明了数值解依概率收敛于方程的解。所得结果覆盖了许多非线性时滞微分方程已经存在的某些理论,而且实验说明此结论比以往的结论更容易验证。     

新控制条件下可数族非扩张映像的强收敛性

研究Banach空间中可数族非扩张映像的收敛性.对于可数族非扩张映像,用Halpern型迭代方法的强收敛性来寻找自反Banach空间中非扩张映像族的公共不动点.通过引入新的控制条件,证明了可数族非扩张映像的收敛性.改进了姚永红和宋义生等人的相应结果.     

中立型随机时滞微分方程截断Milstein数值解的强收敛性

研究非线性系数的Milstein中立型随机时滞微分方程数值解的收敛性问题。将截断思想和Milstein数值格式结合,对有高度非线性系数的中立型随机时滞微分方程,构建了截断Milstein数值格式。在局部Lipschitz条件及Khasminskii条件下,证明了中立型随机时滞微分方程截断Milstein数值解Lp强收敛于精确解。针对一个具体的中立型随机时滞微分方程,使用数值模拟验证了结论的正确性。     

求解带跳随机微分方程的一类全隐式方法

为更好地解决求解带跳的随机微分方程问题,将目前有关求解方程的隐式方法推广到跳跃项的隐式化,进而构造一类新的全隐式方法:补偿θ-Balanced数值方法.首先证明此数值方法是1.5阶均值相容,1阶均方相容;然后证明由此方法所得的数值解是收敛到解析解的,且收敛阶为0.5.最后,通过数值算例说明所构造的数值方法的有效性.     

超松驰方法在正实条件下的收敛性分析

研究使用超松驰（SOR）方法求解正实线性方程组时的收敛性，证明了在适当的选取松驰因子SOR方法是收敛的，进一步丰富了SOR理论，同时给出了SOR方法在对称正交条件下收敛的充要条件的又一新证明。     

Banach空间中渐近非扩张映象迭代序列的强收敛性

在一致Giteaux可微的实Banach空间中，研究一类渐近非扩张映象迭代序列的收敛性，给出强收敛的充分必要条件。     

基于非助剂增溶的分散染料微胶囊非条件配色

对配伍性能极不匹配的纯分散染料进行微胶囊化,改变壁材种类和芯壁比调节微胶囊对分散染料的释放速率,可基本实现非助剂增溶的分散染料微胶囊超细涤纶织物非条件配色。通过测定上染曲线,提升力曲线、K/S值,明暗度L值,红绿轴a值,黄蓝轴b值,色相角H值等相关染色参数考察分散染料的配伍性能,并比较相应染色样品的水洗牢度,摩擦牢度,匀染性。结果表明,常规条件下不能配色的分散染料其配伍性可在非助剂增溶条件下通过微胶囊化加以改善,并可获得与助剂增溶条件下染色样品相当的色牢度,匀染性接近5级。     

预条件(I+C_α)的USSOR迭代法收敛性定理

在预条件矩阵P=I+Cα下提出了新的USSOR迭代法,利用矩阵的分裂理论,讨论了新方法的收敛性,并得到了比较定理,最后给出一个例子来说明结论.     

非等温条件下啮合同向双螺杆挤出过程数值模拟分析

采用SolidWorks建立啮合同向双螺杆三维物理模型,通过改变螺杆挤出机加工聚乳酸时的转速,在非等温的模拟条件下,通过polyflow软件对其进行相应的模拟分析,对比不同转速对聚乳酸加工时产生的影响。结果表明:在非等温条件下,温度在挤出方向上线性增加,并且温度在Z轴截面上沿径向向外逐渐增大。通过对比不同转速下的流场分析,发现随着转速的增大,螺槽内出现较大的温差,当转速达到240r/min时,聚合物出现部分降解,对生产加工产生影响;对剪切速率场和黏度场的对比分析也进一步验证了两者的相关性。     

马尔可夫切换型随机微分方程解的几乎必然稳定性判据

近年来,马尔可夫切换型随机微分方程(MSDE)解的稳定性问题得到了广泛关注,但是用线性矩阵不等式(LMI)的方法来研究MSDE的几乎必然稳定性问题还未见报道.应用LMI来研究MSDE解的几乎必然稳定性问题,首先证明了MSDE解的几乎必然稳定性的一个Lyapunov定理,进而转化为LMI判据,最后通过一个数值例子说明了如何应用,其结果易于用Matlab工具箱进行检验.     

Determination of expressions for the thermal diffusivity of canned foodstuffs by the inverse method and numerical simulations of heat penetration

This paper deals with the determination of expressions to estimate the thermal diffusivity of foodstuffs placed in cans during their pasteurisation. To this end, experimental data of the temperature in the geometric centre of the can were compared with data obtained by simulations of heat penetration. For these simulations, the diffusion equation was numerically solved by using the finite volume method, with fully implicit formulation. The numerical solution was coupled to an optimiser based on the inverse method, in order to fit this solution to the experimental data obtained during the pasteurisation of tomato puree and custard cream placed within sealed cans. In the literature, the assumption of constant thermal diffusivity during the pasteurisation is common but for the analysed cases such hypothesis resulted in biased fits. Better results were obtained supposing an increasing expression for the thermal diffusivity, as function of the local temperature. In this case, the errors of the experimental data about of the numerical solution can be considered randomly distributed.     

A comparison of solid-phase microextraction (SPME) with simultaneous distillation-extraction (SDE) for the analysis of volatile compounds in heated beef and sheep fats

A comparison has been made on the application of SPME and SDE for the extraction of volatile compounds from heated beef and sheep fats with separation and measurement by gas chromatography-mass spectrometry. As far as we know, this report represents the first time that such a comparison has been made for the measurement of volatile compounds in heated sheep fat. Approximately 100 compounds (in relatively high abundance) were characterised in the volatile profiles of heated beef and sheep fats using both techniques. Differences were observed in the volatile profiles obtained from each technique, independent of compound class. Rather than rate one technique as superior to another, the techniques can be regarded as complementary to each other.     

Development and validation of an RP-HPLC method for the analysis of anthraquinones in noni fruits and leaves

Noni fruits and leaves, which have been used traditionally for thousands of years to improve health, are increasingly attracting the interests of consumers and researchers. A selective and validated HPLC method for the analysis of anthraquinones in noni fruits and leaves has been developed and is reported for the first time. Four anthraquinones, 5,15-dimethylmorindol (5,15-DMM, 1), lucidin (2), and alizarin (3), and rubiadin (4) are examined. The limits of detection of 1–4 were in the range of 1.0 and 20.0 ng. Intra- and inter-day precisions of 1 were determined to be less than 5.3%. The accuracy, expressed as the percent recovery of 1 after spiking at three concentrations ranged from 83.0% to 93.3%. Further, the linear correlation coefficient was >0.999, within the range of concentration investigated. The 5,15-DMM content of noni fruit puree and noni leaf infusion are between 0.186 to 0.202 μg/mL (ppm), and 5.82 to 20.93 ng/mL (ppb), respectively. Lucidin, rubiadin and alizarin were not detected in any of the noni samples. The presence of only trace amounts in the noni fruits and leaves may help to eliminate safety concerns regarding anthraquinone contents.     

混料设计优化龙眼、红枣和姜粉复合果蔬粉配方

目的 优化龙眼、红枣和姜复合果蔬粉配方。方法 采用混料设计优化复合果蔬粉配方,将龙眼粉(80%~90%),红枣粉(1%~10%)和姜粉(1%~10%)按不同质量配比组合的复合果蔬粉配方,利用5段嗜好尺度感官评定法评定复合果蔬粉的香气、滋味、溶解性和总体评价4个感官指标,建立配料组成成分与复合果蔬粉感官评价指标之间的回归方程,采用Design Expert统计软件优化得到最佳的配方。结果 龙眼复合果蔬粉优化配方的质量百分比为：龙眼粉90.0%、红枣粉8.4%、姜粉1.6%。经验证实验,此优化配方样品的香气、滋味、溶解性和总体感官评价指标分值分别为3.80、4.00、2.90和3.67,与预测值相符。结论 本研究结果为龙眼复合果蔬粉的实际生产提供了参考依据。     

A developed pre-column derivatization method for the determination of free fatty acids in edible oils by reversed-phase HPLC with fluorescence detection and its application to Lycium barbarum seed oil

Free fatty acids (FFAs) in edible oils are one of the most frequently determined quality indices during production, storage, and marketing. In this study, a simple, stable and sensitive method for the simultaneous determination of saturated and unsaturated FFAs from edible oils using 2-(11H-benzo[a]carbazol-11-yl)-ethyl-4-methylbenzenesulphonate (BCETS) as labelling reagent with fluorescence detection has been established. FFAs are derivatized by BCETS and separated on a reversed-phase Eclipse XDB-C₈ column with a gradient elution. The results indicated that all FFAs were found to be given an excellent linear response with correlation coefficients of >0.9994. The detection limits at a signal-to-noise ratio of 3 were in the range of 0.22–1.06 ng/mL. When applied to Lycium barbarum seed oils, the developed method showed good reproducibility. The effect of extraction methods including supercritical CO₂ and organic solvent extraction on the FFAs composition has also been investigated. Meanwhile, this method exhibits powerful potential for the trace analysis of short- and long-chain free fatty acids from edible oils, foodstuff and other complex samples.     

碎米双酶解成注射用葡萄糖的液化糖化工艺研究

目的:对碎米双酶解法制成注射用葡萄糖的制备工艺中液化与糖化工序展开研究,探求适宜此制备工艺中最佳的液化与糖化工艺条件;方法:采用双酶解法,利用米氏方程数学模型,选用DE值、蛋白质含量、透光率等指标展开研究;结果:碎米的最佳粉碎度为60⁸0目;液化酶的最佳用量为160U·g-1;液化最佳工艺为碎米粉至60目,调浆浓度25%～30%,液化时间30min,CaCl2用量为0.3%,pH为6.0,温度为90～95℃,鸿鹰祥酶用量为160U/g;糖化最佳工艺为鸿鹰祥糖化酶用量为150U/g干物质,普鲁兰酶用量为0.25U/g物质,糖化时间为24h,pH为4.2,温度为60℃。结论:通过本研究,解决了碎米酶解成注射用葡萄糖的液化糖化的最佳工艺条件,为碎米制成注射用葡萄糖奠定了基础。      

SDE-GC-MS与P&T-TD-GC-MS提取分析不同香型凤凰单丛茶香气比较

分别采用同时蒸馏萃取(simultaneous distillation extraction,SDE)法和吹扫捕集热脱附解吸(purge and trap thermal desorption,PT-TD)法提取黄栀香和肉桂香两种香型凤凰单丛茶的香气成分并用气相色谱-质谱进行分析比较。结果表明,2种方法提取的香气成分和相对含量比例有很大差异,两者各有优劣,相互补充,结合分析更加完整,更有利于准确地进行香型分类,并发现PT-TD法有更大的运用空间。SDE法提取的萜烯类化合物较多,脂肪族和芳香族的化合物较少,不同香型的区别主要是成分的相对含量比例;PT-TD法提取得到的成分种类多,不同香型的茶区别较大。通过萜酯指数可得PT-TD法提取的香气更为清香,SDE法提取的香气较为浓烈,但两者都体现了凤凰茶清高持久的幽香特性。SDE法的高温加热可能引起成分的改变,PT-TD提取法的成分较能真实地反应茶汤冲泡的特点。结合2种方法分析得出,黄栀香与肉桂香茶的区别明显,黄栀香茶以荜澄茄醇、橙花叔醇等为主,并特有丙酸芳樟酯、δ-杜松烯、萜品油烯等成分;肉桂香茶是吲哚、δ-壬内酯、苯乙腈相对含量多,且含有苯乙醇、苯甲醇、1,5,8-对-薄荷三烯、戊醛等特有成分。