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Chloride Diffusivity Analysis of Existing Concrete Based on Fick's Second Law
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作者 张俊芝 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第1期142-146,共5页
According to the existing concrete core samples obtained in site, chloride concentration and porosity of existing normal hydraulic concrete were measured, and chloride diffusivity in existing hydraulic concrete was st... According to the existing concrete core samples obtained in site, chloride concentration and porosity of existing normal hydraulic concrete were measured, and chloride diffusivity in existing hydraulic concrete was studied. By Fick’s second law, the chloride diffusion coefficients in the steady diffusion area were calculated. The chloride diffusion of different mix proportion concrete was tested, and chloride diffusion coefficients and porosities of freshly concrete were measured, moreover, the relationship between diffusion coefficient and porosity was analyzed. The results show that the varying law of chloride diffusion coefficient with exposure time of existing concrete can be predicted in a better way by Fick’s second law and water-cement ratios or porosity of concrete and chloride concentration in existing concrete. 展开更多
关键词 existing concrete ficks second diffusion law CHLORIDE diffusion coefficient
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Exact Solution of Fractional Diffusion Model with Source Term used in Study of Concentration of Fission Product in Uranium Dioxide Particle 被引量:2
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作者 房超 曹建主 孙立风 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第5期863-867,共5页
The exact solution of fractional diffusion model with a location-independent source term used in the study of the concentration of fission product in spherical uranium dioxide (U02) particle is built. The adsorption... The exact solution of fractional diffusion model with a location-independent source term used in the study of the concentration of fission product in spherical uranium dioxide (U02) particle is built. The adsorption effect of the fission product on the surface of the U02 particle and the delayed decay effect are also considered. The solution is given in terms of Mittag-Leffler function with finite Hankel integral transformation and Laplace transformation. At last, the reduced forms of the solution under some special physical conditions, which is used in nuclear engineering, are obtained and corresponding remarks are given to provide significant exact results to the concentration analysis of nuclear fission products in nuclear reactor. 展开更多
关键词 fractional diffusion fick's law source term finite Hankel transformation Laplace transformation
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Visual analysis of flow and diffusion of hemolytic agents and hematomas
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作者 Yafei Zhu Mengyao Bao +2 位作者 Miaomiao Jiang Jincai Chang Jianzhong Cui 《Visual Computing for Industry,Biomedicine,and Art》 EI 2021年第1期9-21,共13页
The elimination of intracranial hematomas has received widespread attention and the interactions between hemolytic agents and hematomas have become a hot research topic.In this study,we used the Navier-Stokes equation... The elimination of intracranial hematomas has received widespread attention and the interactions between hemolytic agents and hematomas have become a hot research topic.In this study,we used the Navier-Stokes equation to describe the flow control equation for hemolytic agents in a tube and used Fick’s law and the Maxwell-Stefan diffusion theory to describe the diffusion and mass transfer of hemolytic agents and hematomas.The physical fields and initial boundary conditions were set according to the parametric properties of the fluid and drainage tube.The COMSOL Multiphysics software was used to simulate the streamline distribution of hemolytic agents in a bifurcated drainage tube.Additionally,the diffusion behaviors of the hemolytic agents into hematomas were simulated and visual analysis of coupled multiphysics was performed to realize the digitization and visualization of engineering fluid problems and contribute to the field of medical engineering. 展开更多
关键词 Flow diffusion Navier-stokes equation Tube flow ficks law Maxwell-stefan diffusion equation VIsUALIZATION
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纸质玩具中BPA和BPS化合物的迁移 被引量:1
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作者 葛文亮 吴慧慧 +4 位作者 王领军 徐立伟 匡华 胥传来 刘丽强 《包装工程》 CAS 北大核心 2021年第23期84-91,共8页
目的研究纸质玩具中双酚A(BPA)和双酚S(BPS)经口暴露途径下的迁移规律,并考察BPA和BPS迁移的适用性。方法采用间接酶联免疫(IC-ELISA)检测方法和Fick第二定律研究不同温度(4,37,60℃)、盐浓度(0.001,0.01,0.1 mol/L)、pH(4,7,9)条件下... 目的研究纸质玩具中双酚A(BPA)和双酚S(BPS)经口暴露途径下的迁移规律,并考察BPA和BPS迁移的适用性。方法采用间接酶联免疫(IC-ELISA)检测方法和Fick第二定律研究不同温度(4,37,60℃)、盐浓度(0.001,0.01,0.1 mol/L)、pH(4,7,9)条件下双酚类物质经口暴露下的迁移规律,模拟纸质玩具中BPA和BPS的迁移过程。结果双酚类物质迁移量与温度和盐离子浓度呈正相关,且在酸性和碱性条件的模拟液中溶出增加,纸质玩具中BPA和BPS经口暴露途径下的迁移规律符合Fick第二定律。正常迁移模拟条件下(37℃、盐浓度0.01 mol/L、pH=7的唾液模拟液)测得BPA和BPS的迁移系数分别为1.3×10^(-17),6.6×10^(18)cm^(2)/s。结论基于酶免疫检测方法,构建了纸质玩具中BPA和BPS的迁移模型,并成功应用于预测纸质玩具中双酚类化合物的迁移情况,根据纸质玩具中双酚类物质的迁移模拟实验,计算双酚类物质在不同条件下的扩散系数,并拟合迁移模型,预测盲样中BPA和BPS的迁移情况,与实际迁移情况对比,结果表明理论预测值与实际迁移量基本一致,此项工作对于儿童纸质玩具中双酚类物质的风险性评估具有重要意义。 展开更多
关键词 双酚 IC-ELIsA fick第二定律 扩散系数 迁移模型
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Fick第二定律的应用研究现状与展望 被引量:10
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作者 胡玲 徐芸芸 吴瑾 《河北建筑科技学院学报》 2005年第3期50-53,共4页
Fick第二定律通常被用来描述氯离子在混凝土中的扩散性质,对于Fick第二定律在钢筋混凝土结构寿命预测的应用,已经有许多学者对其进行了研究。本文总结了他们的研究成果,分别从Fick第二定律公式中的各个影响参数出发,对公式进行讨论,并... Fick第二定律通常被用来描述氯离子在混凝土中的扩散性质,对于Fick第二定律在钢筋混凝土结构寿命预测的应用,已经有许多学者对其进行了研究。本文总结了他们的研究成果,分别从Fick第二定律公式中的各个影响参数出发,对公式进行讨论,并且根据公式中各个参数的不确定性,提出了Fick第二定律应用发展方向,即应用随机微分方程理论建立随机模型。 展开更多
关键词 fick第二定律 扩散系数 表面浓度 随机模型
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基于VTK的Fick第二定律动态扩散过程模拟 被引量:1
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作者 张建生 《计算机系统应用》 2012年第12期117-120,共4页
Fick第二定律是固体物理学中关于非稳态条件下的扩散宏观理论基础,动态扩散过程的可视化模拟将有助于研究人员直观快捷地了解和掌握物质扩散对周围物质和环境的影响.使用VTK实现了Fick第二定律在一维条件下动态扩散过程的可视化模拟,为... Fick第二定律是固体物理学中关于非稳态条件下的扩散宏观理论基础,动态扩散过程的可视化模拟将有助于研究人员直观快捷地了解和掌握物质扩散对周围物质和环境的影响.使用VTK实现了Fick第二定律在一维条件下动态扩散过程的可视化模拟,为研究人员应用Fick第二定律以及迅速地直观了解扩散结果提供了有益的参考和方法. 展开更多
关键词 fick第二定律 VTK 动态扩散 模拟
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Radionuclides in primary coolant of a fluoride salt-cooled hightemperature reactor during normal operation 被引量:1
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作者 Guo-Qing Zhang Shuai Wang +5 位作者 Hai-Qing Zhang Xing-Wang Zhu Chao Peng Jun Cai Zhao-Zhong He Kun Chen 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第3期109-114,共6页
The release of fission products from coated particle fuel to primary coolant, as well as the activation of coolant and impurities, were analysed for a fluoride saltcooled high-temperature reactor(FHR) system, and the ... The release of fission products from coated particle fuel to primary coolant, as well as the activation of coolant and impurities, were analysed for a fluoride saltcooled high-temperature reactor(FHR) system, and the activity of radionuclides accumulated in the coolant during normal operation was calculated. The release rate(release fraction per unit time) of fission products was calculated with STACY code, which is modelled mainly based on the Fick's law, while the activation of coolant and impurities was calculated with SCALE code. The accumulation of radionuclides in the coolant has been calculated with a simplified model, which is generally a time integration considering the generation and decay of radionuclides. The results show that activation products are the dominant gamma source in the primary coolant system during normal operation of the FHR while fission products become the dominant source after shutdown. In operation condition,health-impacts related nuclides such as ~3H, and ^(14)C originate from the activation of lithium and coolant impurities including carbon, nitrogen, and oxygen. According to the calculated effective cross sections of neutron activation,~6Li and ^(14)N are the dominant ~3H production source and ^(14)C production source, respectively. Considering the high production rate,~3H and ^(14)C should be treated before being released to the environment. 展开更多
关键词 source TERM FHR PRIMARY COOLANT ficks law diffusion
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Brownian Motion of Decaying Particles: Transition Probability, Computer Simulation, and First-Passage Times 被引量:2
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作者 M. P. Silverman 《Journal of Modern Physics》 2017年第11期1809-1849,共41页
Recent developments in the measurement of radioactive gases in passive diffusion motivate the analysis of Brownian motion of decaying particles, a subject that has received little previous attention. This paper report... Recent developments in the measurement of radioactive gases in passive diffusion motivate the analysis of Brownian motion of decaying particles, a subject that has received little previous attention. This paper reports the derivation and solution of equations comparable to the Fokker-Planck and Langevin equations for one-dimensional diffusion and decay of unstable particles. In marked contrast to the case of stable particles, the two equations are not equivalent, but provide different information regarding the same stochastic process. The differences arise because Brownian motion with particle decay is not a continuous process. The discontinuity is readily apparent in the computer-simulated trajectories of the Langevin equation that incorporate both a Wiener process for displacement fluctuations and a Bernoulli process for random decay. This paper also reports the derivation of the mean time of first passage of the decaying particle to absorbing boundaries. Here, too, particle decay can lead to an outcome markedly different from that for stable particles. In particular, the first-passage time of the decaying particle is always finite, whereas the time for a stable particle to reach a single absorbing boundary is theoretically infinite due to the heavy tail of the inverse Gaussian density. The methodology developed in this paper should prove useful in the investigation of radioactive gases, aerosols of radioactive atoms, dust particles to which adhere radioactive ions, as well as diffusing gases and liquids of unstable molecules. 展开更多
关键词 BROWNIAN Motion Random Walk diffusion RADIOACTIVITY Transition Probability FOKKER-PLANCK EQUATION LANGEVIN EQUATION First Passage ficks law Wiener Process
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Oxidation Kinetics of Aluminum Powders in a Gas Fluidized Bed Reactor in the Potential Application of Surge Arresting Materials
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作者 Hong Shih 《Materials Sciences and Applications》 2019年第3期253-292,共40页
In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arre... In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general. 展开更多
关键词 Aluminum spherical Power GAs FLUIDIZATION Bed Oxidation Mechanism Oxide Growth Rate Gibbs Free Energy Ellingham Diagram Mathematical Modeling Dynamic system Plasma diffusion diffusion Coefficient Crystallographic Defect Vacancy Pressure Temperature Flow Laplace Transform Equation Boundary Condition ficks second law software Experimental Theoretical sURGE ARREsTING MATERIALs Analytical solution
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Theoretical Evidence for Wave Nature of Micro Particle and New Theory of Its Collective Motion in Material
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作者 Takahisa Okino 《Journal of Modern Physics》 2021年第3期260-283,共24页
Since a material is composed of micro particles, investigating behavior of those particles is essentially dominant for materials science. The diffusivity of diffusion equation is relevant to not only a collective moti... Since a material is composed of micro particles, investigating behavior of those particles is essentially dominant for materials science. The diffusivity of diffusion equation is relevant to not only a collective motion of micro particles but also a motion of single particle. An elementary process of diffusion was thus theoretically investigated in a local space and time. As a result, the investigation concluded that the wave nature of micro particle results from denying the mathematical density theorem of a real time in the Newton mechanics. In other words, the basic theory of quantum mechanics is established in accordance with the cause-and-effect relationship in the Newton mechanics, for the first time, regardless of the de Broglie hypothesis. In relation to the collective motion of micro particles, the new diffusion theory was also reasonably established using the universal expression of diffusivity obtained here. In the present paper, the new findings indispensable for the fundamental knowledge in physics are thus systematically discussed in accordance with the theoretical frame in physics. 展开更多
关键词 diffusion ficks laws de Broglie’s Hypothesis schrödinger’s Equation Matter-Wave
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玄武岩纤维混凝土力学性能及氯盐侵蚀行为
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作者 季自刚 任效坤 +3 位作者 孙涛 黄绍宁 周益云 李福海 《混凝土》 CAS 北大核心 2024年第3期57-60,67,共5页
为探究氯盐侵蚀对玄武岩纤维混凝土力学性能的影响及氯盐在混凝土中的侵蚀行为,以抗压强度、劈裂抗拉强度、氯离子沉积量为表征手段进行盐雾侵蚀试验,并根据Fick第二定律计算得到不同侵蚀龄期下氯离子扩散系数。结果表明:混凝土强度在... 为探究氯盐侵蚀对玄武岩纤维混凝土力学性能的影响及氯盐在混凝土中的侵蚀行为,以抗压强度、劈裂抗拉强度、氯离子沉积量为表征手段进行盐雾侵蚀试验,并根据Fick第二定律计算得到不同侵蚀龄期下氯离子扩散系数。结果表明:混凝土强度在氯盐侵蚀过程中呈现先上升后下降的趋势;通过氯盐侵蚀的玄武岩纤维与普通混凝土相比,能有效提高混凝土的抗压及劈裂抗拉强度,降低混凝土劣化速率;在相同深度及侵蚀龄期下玄武岩纤维混凝土氯离子含量均低于普通混凝土;此外,氯离子扩散系数随着侵蚀龄期的增加而降低,且相同龄期下玄武岩纤维混凝土氯离子扩散系数均低于普通混凝土。 展开更多
关键词 玄武岩纤维 力学性能 氯离子含量 fick第二定律 氯离子扩散系数
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Test and prediction of chloride diffusion in recycled aggregate concrete 被引量:5
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作者 XIAO Jian Zhuang YING Jing Wei +1 位作者 TAM Vivian W.Y GILBERT Ian R 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第12期2357-2370,共14页
Recycled aggregate concrete (RAC) specimens with different recycled zoarse aggregate replacement ratios by mass (R) are fully immersed in a 10% chloride solution for 235 days. Both free chloride concentration (CI... Recycled aggregate concrete (RAC) specimens with different recycled zoarse aggregate replacement ratios by mass (R) are fully immersed in a 10% chloride solution for 235 days. Both free chloride concentration (CI) and total chloride concentration (Ct) are then measured employing a rapid chloride test (RCT) system. The Fick's second diffusion law is verified by the test data and used to predict chloride concentration distribution at different immersion periods. Addilionally, pore structures of the new and old mortar in RAC are tested by mercury intrusion porosimetrV (MIP). It is found that bind- ing chloride concentration (Cb) linearly increases with Cf. In natural aggregate concrete (NAC), Cf is obviously smaller than that in the RAC in the same testing environment and this is different from the test results of Ct and Cb. Furthermore, the effects of R on the chloride concentration of RAC become severe for specimens subjected to long immersion periods, which can be explained in terms of the pore structures of the new mortar and old adhesive mortar in RAC. 展开更多
关键词 recycled aggregate concrete (RAC) chloride diffusion rapid chloride test (RCT) pore structure fick's second diffu-sion law chloride binding
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Effect of laminate thickness on moisture diffusion of polymer matrix composites in artificial seawater ageing 被引量:2
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作者 Ratna PAL H.N.NARASIMHA MURTHY +2 位作者 M.SREEJlTHz,K.R.VISHNU MAHESH M.KRISHNA IS.C.SHARMA 《Frontiers of Materials Science》 SCIE CSCD 2012年第3期225-235,共11页
The influence of laminate thickness of polymer matrix composites on moisture diffusion in seawater immersion, as well as the resulting mechanical property degradation for composites of glass/isopolyester (G/IPE), ca... The influence of laminate thickness of polymer matrix composites on moisture diffusion in seawater immersion, as well as the resulting mechanical property degradation for composites of glass/isopolyester (G/IPE), carbon/isopolyester (C/IPE), glass/vinylester (G/VE) and carbon/vinylester (CNE), was investigated in this paper. Laminates 3 and 10 mm in thickness, fabricated using the wet hand lay-up technique, were characterized for moisture absorption in artificial seawater medium, and their flexural strength and interlaminar shear strength (ILSS) degradations were studied. Moisture diffusion was observed to be anamolous to the Fick's law for both 3 and 10 mm thick samples in the later stage of diffusion. Moisture permeability of 10 mm thick samples was two to three order greater than that of 3 mm thick ones, while the time to moisture saturation remained unchanged. With the increase of laminate thickness, moisture saturation increased by 1.4% for CNE and 7% for GriPE. The residual flexural strength and ILSS were greater in case of 10 mm thick specimens after 200 days of exposure. SEM examination of the fractured specimens showed greater levels of fibre/matrix debonding in 10 mm thick specimens. 展开更多
关键词 polymer matrix composite diffusion coefficient fick's law DEGRADATION
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甲烷及二氧化碳在不同煤阶煤内部的吸附扩散行为 被引量:51
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作者 张登峰 崔永君 +2 位作者 李松庚 宋文立 林伟刚 《煤炭学报》 EI CAS CSCD 北大核心 2011年第10期1693-1698,共6页
采用容量法确定吸附量的方法,基于Fick第二定律,在吸附平衡压力约为1.4 MPa,温度为35~65℃的实验条件下,研究了甲烷(CH4)和二氧化碳(CO2)在不同煤阶煤内部的吸附扩散行为。研究结果表明:Fick第二定律能够很好地描述CH4及CO2在不同煤阶... 采用容量法确定吸附量的方法,基于Fick第二定律,在吸附平衡压力约为1.4 MPa,温度为35~65℃的实验条件下,研究了甲烷(CH4)和二氧化碳(CO2)在不同煤阶煤内部的吸附扩散行为。研究结果表明:Fick第二定律能够很好地描述CH4及CO2在不同煤阶煤内部的扩散行为;CH4和CO2有效扩散系数随着吸附温度的升高而增大,同时有效扩散系数和煤阶(利用镜质组最大反射率Ro,max表征)之间呈现"U"形关系;相同条件下,同种煤样的CO2有效扩散系数高于CH4;CH4和CO2在不同煤阶煤内部的扩散主要受微孔内部的表面扩散控制。 展开更多
关键词 甲烷 二氧化碳 吸附 扩散 fick第二定律
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盐雾环境下氯离子在混凝土中的扩散 被引量:17
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作者 刘军 邢锋 +2 位作者 董必钦 丁铸 马红岩 《深圳大学学报(理工版)》 EI CAS 北大核心 2010年第2期192-198,共7页
通过模拟滨海盐雾环境,采用不同配合比的混凝土试样,进行盐雾环境下的腐蚀试验,研究盐雾氯离子在混凝土中的扩散模型.研究发现,盐雾氯离子在混凝土中的扩散与Fick第二定律的解析解存在一定差距.实验引入环境系数概念,提出经修正的Fick... 通过模拟滨海盐雾环境,采用不同配合比的混凝土试样,进行盐雾环境下的腐蚀试验,研究盐雾氯离子在混凝土中的扩散模型.研究发现,盐雾氯离子在混凝土中的扩散与Fick第二定律的解析解存在一定差距.实验引入环境系数概念,提出经修正的Fick第二定律,推导出修正后的解析解.实验结果显示,实测数据和修正的Fick第二定律符合很好.在实际滨海环境下,选取两处有代表性的钢筋混凝土结构,在典型部位抽取芯样,考察了实际盐雾氯离子对混凝土结构的作用,结合当地环境特征,通过拟合数据点,确定环境系数,验证了环境系数在实际混凝土结构中的应用及其评价意义. 展开更多
关键词 混凝土 耐久性 滨海环境 氯离子 盐雾 fick第二定律 扩散模型
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植物油纸绝缘的微水扩散特性 被引量:13
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作者 李剑 陈晓陵 +2 位作者 张召涛 廖瑞金 杨丽君 《高电压技术》 EI CAS CSCD 北大核心 2010年第6期1379-1384,共6页
植物油纸绝缘的微水扩散特性研究,是采用植物绝缘油作为绝缘材料的高压电气设备内部微水质量分数监测与危险性评估的基础。为此,采用费克第二扩散定律一维模型,推导出菜籽绝缘油浸纸微水扩散方程;设计了菜籽绝缘油浸纸微水扩散实验系统... 植物油纸绝缘的微水扩散特性研究,是采用植物绝缘油作为绝缘材料的高压电气设备内部微水质量分数监测与危险性评估的基础。为此,采用费克第二扩散定律一维模型,推导出菜籽绝缘油浸纸微水扩散方程;设计了菜籽绝缘油浸纸微水扩散实验系统及实验方法,根据实验结果拟合出菜籽绝缘油浸纸中微水扩散系数;根据定解条件并采用分离变量法求解,得出菜籽绝缘油浸纸中微水质量分数分布计算公式,并对菜籽绝缘油浸纸微水质量分数动态分布进行了仿真计算,并与矿物绝缘油浸纸微水质量分数分布计算结果进行对比分析。研究结果表明,由于菜籽绝缘油能通过界面粘滞力、亲水性和氢键作用等方式,对微水从菜籽绝缘油向绝缘纸中的扩散具有明显的抑制作用。 展开更多
关键词 植物绝缘油 油纸绝缘 费克第二定律 微水扩散实验 扩散系数 动态分布
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弯曲荷载作用对混凝土中氯离子扩散的影响 被引量:69
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作者 何世钦 贡金鑫 《建筑材料学报》 EI CAS CSCD 2005年第2期134-138,共5页
为研究弯曲荷载对混凝土中氯离子扩散速度的影响,测试了在持续弯曲荷载作用下的混凝土于NaCl溶液中浸泡30,70,120,200 d后的自由氯离子含量.结果表明,持续弯曲荷载作用增加了氯离子在混凝土中的含量,氯离子扩散系数与荷载作用有一定的关系.
关键词 混凝土 弯曲 荷载作用 氯离子扩散系数 NACL溶液 氯离子含量 扩散速度
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中药提取过程的动力学 被引量:62
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作者 储茂泉 刘国杰 《药学学报》 CAS CSCD 北大核心 2002年第7期559-562,共4页
目的 为中药提取工艺设计提供理论依据。方法 基于Fick扩散第二定律 ,建立中药提取过程的动力学方程 ,并以实验对其进行检验。结果 中药提取过程的动力学服从一级动力学方程 ,甘草、五味子、麦冬中有效成分以及丹参中丹参酮的提取等... 目的 为中药提取工艺设计提供理论依据。方法 基于Fick扩散第二定律 ,建立中药提取过程的动力学方程 ,并以实验对其进行检验。结果 中药提取过程的动力学服从一级动力学方程 ,甘草、五味子、麦冬中有效成分以及丹参中丹参酮的提取等实验结果与动力学方程能较好地吻合 ,乙醇提取丹参酮的过程为内扩散控制的 ,其提取表观活化能为 2 0 2 6kJ·mol- 1 。结论 建立的中药提取过程的动力学方程是可靠的。 展开更多
关键词 动力学方程 fick扩散第二定律 丹参酮 有效成分提取 中药生产
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乳清蛋白抗菌薄膜中山梨酸钾的扩散性研究 被引量:6
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作者 张玉亭 雷桥 +2 位作者 包建强 潘家祯 黄志英 《食品工业科技》 CAS CSCD 北大核心 2015年第13期262-265,287,共5页
将山梨酸钾添加至乳清分离蛋白成膜液中制成抗菌包装薄膜,通过扩散实验并结合菲克扩散理论,研究了在不同浓度、温度、p H条件下抗菌蛋白薄膜中山梨酸钾的扩散行为。根据幂律模型的扩散指数,发现p H3.8时山梨酸钾的初期释放动力学属于非... 将山梨酸钾添加至乳清分离蛋白成膜液中制成抗菌包装薄膜,通过扩散实验并结合菲克扩散理论,研究了在不同浓度、温度、p H条件下抗菌蛋白薄膜中山梨酸钾的扩散行为。根据幂律模型的扩散指数,发现p H3.8时山梨酸钾的初期释放动力学属于非菲克扩散,而在其他条件下基本符合菲克第一扩散定律。扩散系数研究表明:抗菌膜中山梨酸钾浓度增加,温度升高,p H降低,扩散系数呈非线性增大;模拟液p H3.8时,由于薄膜溶胀性较大,山梨酸钾的扩散系数在35℃条件下高达5.722×10-12m2/s;通过阿伦尼乌斯公式中活化能比较,发现山梨酸钾的扩散系数在p H为3.8的模拟液中最易受温度影响。 展开更多
关键词 山梨酸钾 乳清蛋白膜 溶胀 菲克定律 扩散性
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典型油纸绝缘微水扩散特性仿真分析及试验研究 被引量:7
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作者 彭倩 李先浪 +3 位作者 姚晓 王晓剑 陈凌 吴广宁 《高压电器》 CAS CSCD 北大核心 2014年第1期31-36,共6页
绝缘纸受潮将严重影响变压器的内绝缘特性,变压器油纸绝缘体系中微水含量及微水分布状况是评估变压器绝缘状态的重要依据。基于菲克第二定律建立了油纸绝缘微水扩散的3种典型模型,并采用分离变量法和有限元方法对模型进行了仿真模拟。... 绝缘纸受潮将严重影响变压器的内绝缘特性,变压器油纸绝缘体系中微水含量及微水分布状况是评估变压器绝缘状态的重要依据。基于菲克第二定律建立了油纸绝缘微水扩散的3种典型模型,并采用分离变量法和有限元方法对模型进行了仿真模拟。模拟了有化学反应参与的微水扩散过程,更符合绝缘纸长时间老化的微水扩散过程。搭建了微水随绝缘纸厚度梯度分布时测试实验平台,采用微水测试传感器测量微水含量。结合实验测量数据和微水扩散的有限元模型以及广泛采用的微水扩散系数经验公式,采用遗传算法寻优,获得了优化的微水扩散分布曲面。 展开更多
关键词 油纸绝缘 微水分布 菲克第二定律 绝缘纸老化 有限元分析 遗传算法
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