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Stability and Approximate Analytical Periodic Solution of a Structurally Orthotropic Stringer Shell 认领
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作者 Xia Liu Ruifang Wang Fabao Gao 《应用数学与应用物理(英文)》 2020年第3期481-491,共11页
Combined with real engineering, we mainly study the stability of the equilibrium state at the coordinate center of an orthotropic stringer shell system, and the approximate analytic periodic motion is presented around... Combined with real engineering, we mainly study the stability of the equilibrium state at the coordinate center of an orthotropic stringer shell system, and the approximate analytic periodic motion is presented around the studied equilibrium state. In addition the rationality of the obtained results is verified by numerical simulation. Furthermore we found that there are actually only four kinds of phase portrait of this type of shell. 展开更多
关键词 STABILITY Periodic Solution STRINGER SHELL SUCCESSOR Function
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Multiple Lagrange stability and Lyapunov asymptotical stability of delayed fractional-order Cohen-Grossberg neural networks 认领
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作者 黄玉娇 袁孝焰 +2 位作者 杨旭华 龙海霞 肖杰 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第2期196-205,共10页
This paper addresses the coexistence and local stability of multiple equilibrium points for fractional-order Cohen-Grossberg neural networks(FOCGNNs)with time delays.Based on Brouwer's fixed point theorem,sufficie... This paper addresses the coexistence and local stability of multiple equilibrium points for fractional-order Cohen-Grossberg neural networks(FOCGNNs)with time delays.Based on Brouwer's fixed point theorem,sufficient conditions are established to ensure the existence of Πi=1^n(2Ki+1)equilibrium points for FOCGNNs.Through the use of Hardy inequality,fractional Halanay inequality,and Lyapunov theory,some criteria are established to ensure the local Lagrange stability and the local Lyapunov asymptotical stability of Πi=1^n(Ki+1)equilibrium points for FOCGNNs.The obtained results encompass those of integer-order Hopfield neural networks with or without delay as special cases.The activation functions are nonlinear and nonmonotonic.There could be many corner points in this general class of activation functions.The structure of activation functions makes FOCGNNs could have a lot of stable equilibrium points.Coexistence of multiple stable equilibrium points is necessary when neural networks come to pattern recognition and associative memories.Finally,two numerical examples are provided to illustrate the effectiveness of the obtained results. 展开更多
关键词 FRACTIONAL-ORDER COHEN-GROSSBERG neural networks MULTIPLE Lagrange STABILITY MULTIPLE LYAPUNOV asymptotical STABILITY time DELAYS
刚性脉冲微分方程Runge-Kutta方法的稳定性和收敛性 认领
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作者 余越昕 文海洋 +1 位作者 肖荣 杨传影 《湘潭大学学报:自然科学版》 CAS 2020年第2期1-6,共6页
将Runge-Kutta方法用于求解刚性脉冲微分方程,获得了(k,l)-代数稳定的Runge-Kutta方法稳定及渐近稳定的条件.同时证明了求解刚性常微分方程r阶B-收敛的Runge-Kutta方法用于求解刚性脉冲微分方程也是r阶B-收敛的.
关键词 刚性脉冲微分方程 RUNGE-KUTTA方法 稳定性 渐近稳定性 收敛性
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70 nm: The most unstable grain size in Cu prepared by surface mechanical grinding treatment 认领
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作者 Xin Zhou Xiuyan Li Ke Lu 《纳米材料科学:英文版》 CAS 2020年第1期32-38,共7页
The stability of Cu with different average grain sizes prepared by surface mechanical grinding treatment were investigated under the conditions of isothermal annealing and uniaxial tension.In both conditions,experimen... The stability of Cu with different average grain sizes prepared by surface mechanical grinding treatment were investigated under the conditions of isothermal annealing and uniaxial tension.In both conditions,experimental results revealed that the stability of the grains decreased with the decrease of grain size when the grain size was above 70–75 nm,while the stability of the grains increased with the decrease of grain size when the grain size was below 70–75 nm.The grains of about 70–75 nm in size showed the worst stability in both thermal and mechanical conditions due to having the highest level of average atom free energy and their large amount of high energy grain boundary with large curvature.This size was very close to the calculated smallest size achievable by severe plastic deformation based on the grain refinement mechanism of dislocation evolution under present processing condition,at which both the highest density of dislocation and highest energy should be produced and induces poor stability.Below 70 nm,the deformation mechanism of nanograined Cu was transformed into a partial dislocation motion,which activated mechanically induced grain boundary(GB)relaxation accompanied by GB flattening and GB energy decrease and resulted in enhanced stability.This discovery offers the potential for developing nanograined metals with high strength and high stability. 展开更多
关键词 NANOGRAINS Thermal STABILITY Mechanical STABILITY ATOM free energy Copper SEVERE plastic deformation
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Influence of Wheelchair Cushions Fabricated by Therapists on Stability, Comfort, and Functionality 认领
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作者 Takeshi Oshikawa Seigo Koura +2 位作者 Nishikawa Chihoko Kazuho Nagao Kentaro Higashi 《康复医学(英文)》 2020年第1期1-11,共11页
“Ease of comfort” and “functionality” are important factors that have been cited to improve wheelchair seating. The ability to maintain balance and posture while seated in a wheelchair improves stability, comfort,... “Ease of comfort” and “functionality” are important factors that have been cited to improve wheelchair seating. The ability to maintain balance and posture while seated in a wheelchair improves stability, comfort, and functionality and is a prerequisite for daily activities. In this study, the authors used a sitting position measuring device to scientifically verify differences in sitting posture, comfort, and functionality depending on the presence or absence of cushions and the type of cushion in elderly individuals who used wheelchairs. Results suggested that a cushion fabricated by a therapist was more useful than a commercially available air cushion. While a commercially available air cushion was the most suitable, the therapist’s self-made cushion could be expected to demonstrate the same or better applicability than an air cushion. 展开更多
关键词 WHEELCHAIR SITTING STABILITY CUSHION COMFORT FUNCTIONALITY
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D3-C32F2的稳定性和振动光谱的理论研究 认领
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作者 查林 《山西化工》 2020年第3期6-9,共4页
应用密度泛函理论在B3LYP/6-31G(d)水平上对D3-C32的二元氟化衍生异构体进行几何优化,对优化结构的反应热和前线轨道能级差的分析表明,D3-C32F2在热力学上是稳定的,最稳定的异构体是1-8加成的D3-C32F2-1-32,振动频率计算发现,对称性会... 应用密度泛函理论在B3LYP/6-31G(d)水平上对D3-C32的二元氟化衍生异构体进行几何优化,对优化结构的反应热和前线轨道能级差的分析表明,D3-C32F2在热力学上是稳定的,最稳定的异构体是1-8加成的D3-C32F2-1-32,振动频率计算发现,对称性会影响结构的最大振动频率及强度,衍生化位置对称性越高,振动强度越大。 展开更多
关键词 D3-C32F2 稳定性 振动光谱 密度泛函理论稳定性 振动光谱 密度泛函理论
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Genotype by Environment Interaction for Grain Yield and Association among Stability Parameters in Bread Wheat (<i>Triticum aestivum</i>L.) 认领
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作者 Alemayehu Balcha 《美国植物学期刊(英文)》 2020年第1期1-10,共10页
Bread wheat (Triticum aestivum L.) is most important cereal crop in Ethiopia. Lack of genotypes with wide stability across environments has been one of the most important constraints of wheat production in the country... Bread wheat (Triticum aestivum L.) is most important cereal crop in Ethiopia. Lack of genotypes with wide stability across environments has been one of the most important constraints of wheat production in the country. Field experiments were conducted in Halaba and Bule, South Ethiopia, in 2016 and 2017, in order to estimate grain yield stability and association among stability parameters. Fifteen improved bread wheat genotypes were grown under randomized complete block design with three replications. Mean yield for Halaba 2016, Halaba 2017, Bule 2016 and Bule 2017 was 3.83, 1.89, 2.90 and 3.59 tons/ha, respectively. Genotypes Lemu (3.25 tons/ha) and Mandoyu (3.18 tons/ha) had high mean yield, and low values of environmental variance (S2i), coefficient of variation (CVi), stability variance (δ2i), ecovalence (Wi) and deviation from regression (S2di). Genotypes Biqa (3.69 tons/ha) and Shorima (3.66 tons/ha) had high mean yield, coefficient of regression (bi) and coefficient of determination (R2i ≥ 0.94) as well as low values of δ2i, Wi and S2di. Grain yield had positive rank correlation with bi (r = 0.75, p 2i (r = 0.70, p δ2i, Wi and S2di was high (r ≥ 0.98, p , Mandoyu and Hidase, and Biqa and Shorima would be recommended for wide adaption, and for more favorable environments, respectively. It could also be suggested that one of Wi, δ2i, S2di and rank sum would be used for ranking of genotypes. 展开更多
关键词 Grain Yield Stability Rank Correlations Bread Wheat TRITICUM AESTIVUM
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A Class of Semi-Implicit Parallel Difference Method for Time Fractional Diffusion Equations 认领
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作者 Lifei Wu Jiake Sun Xiaozhong Yang 《应用数学与应用物理(英文)》 2020年第1期158-171,共14页
In this paper, we construct a class of semi-implicit difference method for time fractional diffusion equations—the group explicit (GE) difference scheme, which is a difference scheme with good parallelism constructed... In this paper, we construct a class of semi-implicit difference method for time fractional diffusion equations—the group explicit (GE) difference scheme, which is a difference scheme with good parallelism constructed using Saul’yev asymmetric scheme. The stability and convergence of the GE scheme of time fractional diffusion equation are analyzed by mathematical induction. Then, the theoretical analysis is verified by numerical experiments, which shows that the GE scheme is effective for solving the time fractional diffusion equation. 展开更多
关键词 Time FRACTIONAL Diffusion Equation Group EXPLICIT Scheme Stability PARALLEL COMPUTATION Numerical Experiment
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A finite-time 3D guidance law based on fixed-time convergence disturbance observer 认领
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作者 Feng YANG Guangqing XIA 《中国航空学报:英文版》 SCIE EI CAS CSCD 2020年第4期1299-1310,共12页
In order to achieve accurate interception of high-speed maneuvering targets,this paper presents a relative Line-of-Sight(LOS)velocity based finite-time three-dimensional guidance law design framework,and discusses the... In order to achieve accurate interception of high-speed maneuvering targets,this paper presents a relative Line-of-Sight(LOS)velocity based finite-time three-dimensional guidance law design framework,and discusses the application of fixed-time convergence disturbance observer in this framework.Firstly,a simple Lyapunov function is provided to show that the coupled terms in the relative kinematics can be ignored in the proposed guidance law design framework.Secondly,the realizations of several classical guidance laws are analyzed with the proposed framework,including TPN guidance law,finite-time Input-to-State Stability(ISS)guidance law,and sliding mode guidance law.Thirdly,fixed-time convergence disturbance observers are introduced to design the composite finite-time 3D guidance law,and Lyapunov method is employed to show the stability of the guidance system.Numerical simulations with different scenarios show that the proposed generalized guidance law performs high interception accuracy. 展开更多
关键词 DISTURBANCE Finite-time stability Fixed-time stability Guidance law OBSERVER
核桃乳的最佳存放条件探讨 认领
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作者 赵慧博 夏君霞 +3 位作者 齐兵 路敏 徐姗 吴彦兵 《现代食品科技》 EI CAS 北大核心 2020年第8期241-245,174,共6页
为探究PET装核桃乳的最佳存放条件,利用Turbiscan Lab稳定性分析仪测定了不同处理料液的稳定性,通过单因素实验、正交实验及验证实验确定了存放温度、时间及照度对料液稳定性的影响及其最佳条件组合,并解释了不同因素水平的选择、组合... 为探究PET装核桃乳的最佳存放条件,利用Turbiscan Lab稳定性分析仪测定了不同处理料液的稳定性,通过单因素实验、正交实验及验证实验确定了存放温度、时间及照度对料液稳定性的影响及其最佳条件组合,并解释了不同因素水平的选择、组合的可能机制。结果表明,核桃乳产品生产后常温、照度为30 lx条件下,放置10 d,稳定性指数值最小,即此时料液处于最佳保存状态,选定的三个因素中,稳定性影响力次序为:温度>时间>照度;其可能的机制是,此条件下,PET装核桃乳非均相液体体系,热力学上分子融合及动力学上重力分层所致不稳定性的影响因素之间的制约;料液稳定性的影响涉及乳化等具体加工工艺,因此,不同生产工艺的核桃乳最佳存放条件与本研究结果可能存在差异。 展开更多
关键词 核桃乳 稳定性 分散稳定性分析仪
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The Dynamical Behavior of a Predator-Prey System with Holling Type II Functional Response and Allee Effect 认领
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作者 Shuangte Wang Hengguo Yu +1 位作者 Chuanjun Dai Min Zhao 《应用数学(英文)》 2020年第5期407-425,共19页
In this paper, we mainly considered the dynamical behavior of a predator-prey system with Holling type II functional response and Allee-like effect on predator, including stability analysis of equilibria and Hopf bifu... In this paper, we mainly considered the dynamical behavior of a predator-prey system with Holling type II functional response and Allee-like effect on predator, including stability analysis of equilibria and Hopf bifurcation. Firstly, we gave some sufficient conditions to guarantee the existence, the local and global stability of equilibria as well as non-existence of limit cycles. By using the cobweb model, some cases about the existence of interior equilibrium are also illustrated with numerical outcomes. These existence and stability conclusions of interior equilibrium are also suitable in corresponding homogeneous reaction-diffusion system subject to the Neumann boundary conditions. Secondly, we theoretically deduced that our system has saddle-node bifurcation, transcritical bifurcation and Hopf bifurcation under certain conditions. Finally, for the Hopf bifurcation, we choose d as the bifurcation parameter and presented some numerical simulations to verify feasibility and effectiveness of the theoretical derivation corresponding to the existence of yk, respectively. The Hopf bifurcations are supercritical and limit cycles generated by the critical points are stable. 展开更多
关键词 PREDATOR-PREY System HOLLING Type II FUNCTIONAL Response Allee Effect Stability HOPF BIFURCATION
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大倾角“三软”煤层综放工作面支架稳定性分析 认领
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作者 徐龙龙 呼前广 《煤炭技术》 CAS 2020年第8期24-26,共3页
针对大倾角三软煤层走向长壁综放工作面支架稳定性,通过在不同状态下支架稳定性力学模型的构建,科学分析了长山子煤矿1121工作面倒架原因,并提出"液压油缸+绞车+单体液压支柱"的扶架措施,取得了很好的扶架效果。
关键词 大倾角 三软煤层 支架 稳定性 扶架措施
大跨度单线铁路连续梁拱空间稳定性分析 认领
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作者 龚俊虎 《交通科技》 2020年第2期20-23,40共5页
由于单线铁路大跨度连续梁拱组合结构横向宽度小,因此,需要重点关注结构的横向刚度和整体稳定性。文中以国内最大跨度的单线铁路连续梁拱——乐清湾铁路楠溪江特大桥主桥70 m+136 m+70 m连续梁拱为例,采用midas软件建立全桥空间有限元模... 由于单线铁路大跨度连续梁拱组合结构横向宽度小,因此,需要重点关注结构的横向刚度和整体稳定性。文中以国内最大跨度的单线铁路连续梁拱——乐清湾铁路楠溪江特大桥主桥70 m+136 m+70 m连续梁拱为例,采用midas软件建立全桥空间有限元模型,分析了结构的空间弹性稳定性,并对全桥横向倾覆稳定性进行了分析。结果表明,该单线铁路大跨度连续梁拱的拱肋面外稳定系数为6.396,面内竖向稳定系数为41.316,满足拱结构稳定系数不小于5的要求;拱肋的面外稳定储备远小于面内稳定储备,面外稳定性是单线连续梁拱的设计控制因素之一,应引起足够重视;在最不利荷载组合作用下,全桥横向倾覆稳定系数为3.95,满足横向倾覆稳定系数不小于1.3的要求。 展开更多
关键词 单线铁路 连续梁拱 钢管混凝土拱桥 稳定性 横向倾覆 稳定系数
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LEM-DEM coupling for slope stability analysis 认领
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作者 XU WenJie WANG Shi BILAL Manzoor 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2020年第2期329-340,共12页
Slope stability analysis is a keen area of interest to researchers of geotechnical engineering and geological hazards. To date, the most popular approach applied in slope engineering design is the limit equilibrium me... Slope stability analysis is a keen area of interest to researchers of geotechnical engineering and geological hazards. To date, the most popular approach applied in slope engineering design is the limit equilibrium method(LEM). However, for this method,some assumptions are required when obtaining the sliding force and the resistance force on the slide face. The discrete element method(DEM) presents an advantage in the calculation of the interaction forces between adjacent blocks without assumptions.This paper introduces a new slope stability analysis based on coupling of both approaches, herein referred to as LEM-DEM. The main LEM-DEM procedure is to transform the slice model of a slope in LEM into the DEM model and obtain the sliding force and the resistance force to calculate the factor of stability(Fos). The sensitivity analysis of the parameters in DEM, such as normal and shear stiffness, was conducted to illustrate that LEM-DEM suggests higher contact stiffness. A comparison between the Fos values in DEM and LEM-DEM was also conducted to indicate the rationality and advantages of LEM-DEM, especially for a gentle slope with a changing shear force direction in the slice model where the interslice forces in LEM are unreasonable.Furthermore, this study carried out a 3 D landslide stability analysis extension, along with the results, for the proposed method. 展开更多
关键词 limit EQUILIBRIUM method(LEM) discrete element method(DEM) SLOPE STABILITY factor of stability(Fos) coupling
提高变频器驱动型提升机运行稳定性的策略研究 认领
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作者 闫珂 《机械管理开发》 2020年第3期58-60,共3页
基于常规控制方式下提升机稳定域相对较小的问题,提出了一种以权重前馈为基础的提升机控制方案,并搭建了实验系统,通过实验验证了该种控制方案的可行性。实验结果表明,应用该方案可以确保提升机在弱电网背景下的运行稳定域得到不断扩大... 基于常规控制方式下提升机稳定域相对较小的问题,提出了一种以权重前馈为基础的提升机控制方案,并搭建了实验系统,通过实验验证了该种控制方案的可行性。实验结果表明,应用该方案可以确保提升机在弱电网背景下的运行稳定域得到不断扩大,确保变频器驱动型提升机具备较强的稳定性。 展开更多
关键词 提升机 稳定性 稳定域 滤波器 控制方案
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基于线性多步法的波形松弛方法的线性稳定性 认领
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作者 范振成 《数值计算与计算机应用》 2020年第1期58-67,共10页
波形松弛(WR)方法的研究成果丰富,但主要集中于收敛性,罕见关于稳定性的研究.研究基于线性多步法的WR方法的线性稳定性,获得了线性稳定的几个充分条件,给出了一些具体的线性稳定WR方法的例子,并提供了一些支持理论结果的数值算例.
关键词 稳定 线性稳定 波形松弛方法 线性多步法
建筑工程钢结构稳定性设计分析 认领
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作者 梁冠华 《建材技术与应用》 2020年第2期34-36,共3页
通过对钢结构固有的特性和钢结构稳定性设计的理论进行阐述,结合部分容易产生的钢结构稳定性不足的原因,提出了优化钢结构稳定性设计的措施。
关键词 钢结构 稳定性 稳定性设计 计算
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抚顺西露天矿边坡治理中不同疏干排水方案的对比 认领
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作者 马熹焱 《露天采矿技术》 CAS 2020年第2期73-75,78共4页
对抚顺西露天矿北帮研究区进行水文地质调查,找出出水点及出水原因,提出了水平疏干孔、疏干井、疏干巷道3种边坡水疏干方案并对疏干前后露天矿边坡稳定性进行研究。结果显示,疏干排水对于提高边坡稳定有显著的效果,并选定水平放水孔为... 对抚顺西露天矿北帮研究区进行水文地质调查,找出出水点及出水原因,提出了水平疏干孔、疏干井、疏干巷道3种边坡水疏干方案并对疏干前后露天矿边坡稳定性进行研究。结果显示,疏干排水对于提高边坡稳定有显著的效果,并选定水平放水孔为最终疏干方案。可为露天矿研究区的疏干排水研究和安全生产提供理论依据。 展开更多
关键词 露天矿 边坡 疏干排水方案 稳定性 稳定系数
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浅谈新形势下如何稳定青年员工队伍 认领
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作者 石湘玉 《中小企业管理与科技》 2020年第5期126-127,共2页
青年员工是保证企业可持续发展的生力军,构建稳定的青年员工队伍关系到企业的长远发展。随着社会经济的不断发展,青年员工的诉求日趋多元化。如何立足于新形势构建稳定的青年员工队伍是企业经营管理的重要内容。论文以新形势下青年员工... 青年员工是保证企业可持续发展的生力军,构建稳定的青年员工队伍关系到企业的长远发展。随着社会经济的不断发展,青年员工的诉求日趋多元化。如何立足于新形势构建稳定的青年员工队伍是企业经营管理的重要内容。论文以新形势下青年员工队伍建设面临的机遇与挑战作为切入点,阐述影响青年员工稳定性的因素,最后提出稳定青年员工的具体对策,以期提升企业后备军的质量。 展开更多
关键词 新形势 青年员工 稳定 思想政治教育
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响应面法优化紫兰草紫色素提取工艺及其稳定性研究 认领
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作者 李云婷 陈炼红 +1 位作者 王琳琳 张岩 《中国食品添加剂》 CAS 2020年第5期87-94,共8页
为优化紫兰草紫色素提取工艺并对其稳定性进行研究,在单因素试验基础之上,以提取温度、料液比和提取时间为影响因素,蒸馏水为提取剂,吸光度值为响应值,利用Box-Behnken中心组合法进行三因素三水平响应面分析试验;同时,研究pH、光照、蔗... 为优化紫兰草紫色素提取工艺并对其稳定性进行研究,在单因素试验基础之上,以提取温度、料液比和提取时间为影响因素,蒸馏水为提取剂,吸光度值为响应值,利用Box-Behnken中心组合法进行三因素三水平响应面分析试验;同时,研究pH、光照、蔗糖、NaCl、金属离子、氧化剂和还原剂等因素对紫色素稳定性的影响。结果表明:经响应面法优化得到最佳提取工艺条件为提取温度38℃、料液比1∶24g/mL、提取时间60min,该工艺条件所得响应值与理论值相对误差为0.28;同时,此条件下提取的紫色素具耐酸性,易受光照影响,耐受蔗糖能力较强,NaCl具增色作用,除了Cu^2+以外,对大部分金属离子较稳定;在氧化剂中稳定性较好。本研究用响应面法优化了紫兰草紫色素的提取工艺,并验证出所提取的紫色素具有良好的稳定性。 展开更多
关键词 紫兰草 紫色素 响应面法 提取工艺 稳定性
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