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A Spectral Convolutional Neural Network Model Based on Adaptive Fick’s Law for Hyperspectral Image Classification
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作者 Tsu-Yang Wu Haonan Li +1 位作者 Saru Kumari Chien-Ming Chen 《Computers, Materials & Continua》 SCIE EI 2024年第4期19-46,共28页
Hyperspectral image classification stands as a pivotal task within the field of remote sensing,yet achieving highprecision classification remains a significant challenge.In response to this challenge,a Spectral Convol... Hyperspectral image classification stands as a pivotal task within the field of remote sensing,yet achieving highprecision classification remains a significant challenge.In response to this challenge,a Spectral Convolutional Neural Network model based on Adaptive Fick’s Law Algorithm(AFLA-SCNN)is proposed.The Adaptive Fick’s Law Algorithm(AFLA)constitutes a novel metaheuristic algorithm introduced herein,encompassing three new strategies:Adaptive weight factor,Gaussian mutation,and probability update policy.With adaptive weight factor,the algorithmcan adjust theweights according to the change in the number of iterations to improve the performance of the algorithm.Gaussianmutation helps the algorithm avoid falling into local optimal solutions and improves the searchability of the algorithm.The probability update strategy helps to improve the exploitability and adaptability of the algorithm.Within the AFLA-SCNN model,AFLA is employed to optimize two hyperparameters in the SCNN model,namely,“numEpochs”and“miniBatchSize”,to attain their optimal values.AFLA’s performance is initially validated across 28 functions in 10D,30D,and 50D for CEC2013 and 29 functions in 10D,30D,and 50D for CEC2017.Experimental results indicate AFLA’s marked performance superiority over nine other prominent optimization algorithms.Subsequently,the AFLA-SCNN model was compared with the Spectral Convolutional Neural Network model based on Fick’s Law Algorithm(FLA-SCNN),Spectral Convolutional Neural Network model based on Harris Hawks Optimization(HHO-SCNN),Spectral Convolutional Neural Network model based onDifferential Evolution(DE-SCNN),SpectralConvolutionalNeuralNetwork(SCNN)model,and SupportVector Machines(SVM)model using the Indian Pines dataset and PaviaUniversity dataset.The experimental results show that the AFLA-SCNN model outperforms other models in terms of Accuracy,Precision,Recall,and F1-score on Indian Pines and Pavia University.Among them,the Accuracy of the AFLA-SCNN model on Indian Pines reached 99.875%,and the Accuracy on PaviaUniversity reached 98.022%.In conclusion,our proposed AFLA-SCNN model is deemed to significantly enhance the precision of hyperspectral image classification. 展开更多
关键词 Adaptive fick’s law algorithm spectral convolutional neural network metaheuristic algorithm intelligent optimization algorithm hyperspectral image classification
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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 fick’s second diffusion law CHLORIDE diffusion coefficient
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Origin, Alternative Expressions of Newcomb-Benford Law and Deviations of Digit Frequencies
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作者 Gene Whyman 《Applied Mathematics》 2021年第7期576-586,共11页
The Newcomb-Benford law, which describes the uneven distribution of the frequencies of digits in data sets, is by its nature probabilistic. Therefore, the main goal of this work was to derive formulas for the permissi... The Newcomb-Benford law, which describes the uneven distribution of the frequencies of digits in data sets, is by its nature probabilistic. Therefore, the main goal of this work was to derive formulas for the permissible deviations of the above frequencies (confidence intervals). For this, a previously developed method was used, which represents an alternative to the traditional approach. The alternative formula expressing the Newcomb-Benford law is re-derived. As shown in general form, it is numerically equivalent to the original Benford formula. The obtained formulas for confidence intervals for Benford’s law are shown to be useful for checking arrays of numerical data. Consequences for numeral systems with different bases are analyzed. The alternative expression for the frequencies of digits at the second decimal place is deduced together with the corresponding deviation intervals. In general, in this approach, all the presented results are a consequence of the positionality property of digital systems such as decimal, binary, etc. 展开更多
关键词 Benford’s law Confidence Intervals in Benford’s law Alternative Expression of Benford’s law Benford’s law for Different Numeral systems Frequencies of Digits at the second Decimal Place
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New Interpretation of Newton’s Law of Universal Gravitation
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作者 Dalgerti L. Milanese 《Journal of High Energy Physics, Gravitation and Cosmology》 2017年第4期600-623,共24页
Elliptical motions of orbital bodies are treated here using Fourier series, Fortescue sequence components and Clarke’s instantaneous space vectors, quantities largely employed on electrical power systems analyses. Us... Elliptical motions of orbital bodies are treated here using Fourier series, Fortescue sequence components and Clarke’s instantaneous space vectors, quantities largely employed on electrical power systems analyses. Using this methodology, which evidences the analogy between orbital systems and autonomous second-order electrical systems, a new theory is presented in this article, in which it is demonstrated that Newton’s gravitational fields can also be treated as a composition of Hook’s elastic type fields, using the superposition principle. In fact, there is an identity between the equations of both laws. Furthermore, an energy analysis is conducted, and new concepts of power are introduced, which can help a better understanding of the physical mechanism of these quantities on both mechanical and electrical systems. The author believes that, as a practical consequence, elastic type gravitational fields can be artificially produced with modern engineering technologies, leading to possible satellites navigation techniques, with less dependency of external sources of energy and, even, new forms of energy sources for general purposes. This reinterpretation of orbital mechanics may also be complementary to conventional study, with implications for other theories such as relativistic, quantum, string theory and others. 展开更多
关键词 ORBITAL MOTIONs Gravity Newton’s second law Hook’s Elastic FORCEs Fourier Electrical Circuits TRANsFORMATIONs of Fortescue and Clarke Instantaneous space VECTORs Instantaneous Complex Power
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用Fick第二定律描述混凝土中氯离子浓度分布的适用性 被引量:15
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作者 刘芳 宋志刚 +1 位作者 潘仁泉 金伟良 《混凝土与水泥制品》 2005年第4期7-10,共4页
结合室内试验及现场试验所测得的氯离子浓度分布,与Fick第二定律给出的氯离子浓度分布曲线进行比较,分析了不同侵蚀环境下氯离子浓度分布的特点并计算了其与Fick分布两者间的相关性。结果表明,Fick第二定律适用于室内试验环境、现场盐... 结合室内试验及现场试验所测得的氯离子浓度分布,与Fick第二定律给出的氯离子浓度分布曲线进行比较,分析了不同侵蚀环境下氯离子浓度分布的特点并计算了其与Fick分布两者间的相关性。结果表明,Fick第二定律适用于室内试验环境、现场盐雾作用环境和海水浸泡环境,经适当修正后,还可适用于有碳化或硫酸根影响的环境,但不适用于海水反复淋溅作用下的环境。 展开更多
关键词 混凝土 耐久性 氯离子 fick第二定律 淋溅作用
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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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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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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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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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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 fick’s law Diffusion
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基于Fick-小波包变换方法对土壤CO_2浓度时间序列的去噪处理 被引量:3
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作者 谢宝良 胡军国 +2 位作者 李烨斐 陈芳 毛国平 《传感技术学报》 CAS CSCD 北大核心 2019年第5期715-722,共8页
土壤CO_2浓度时间序列的数据质量易受到外界环境及土壤监测仪质量的影响,导致不能精确的测定土壤呼吸。针对土壤CO_2浓度时间序列的数据质量问题,本文提出小波包变换和Fick第二定律结合的方法对时间序列进行去噪分析。实验结果显示,无... 土壤CO_2浓度时间序列的数据质量易受到外界环境及土壤监测仪质量的影响,导致不能精确的测定土壤呼吸。针对土壤CO_2浓度时间序列的数据质量问题,本文提出小波包变换和Fick第二定律结合的方法对时间序列进行去噪分析。实验结果显示,无论从均值,信噪比,均方根误差和斜率距离来看,本文算法都优于由传统方法计算得到的结果。同时,在研究区域分别测量了早中晚三个时间段的土壤CO_2浓度,对其进行去噪处理之后,利用Fick第一定律计算获得的土壤碳通量与LI-8100测得的仅相距1μmol/m^2/s左右。说明通过本文算法不仅精确算得了开放型气室内任意时间任意位置的CO_2浓度时间序列,并且通过计算处理后的时间序列获得了与LI-8100相近的土壤碳通量。 展开更多
关键词 小波包变换 时间序列去噪 fick定律 土壤CO2浓度 土壤碳通量
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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 fick’s law Wiener Process
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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 fick’s law Maxwell-stefan diffusion equation VIsUALIZATION
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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 fick’s 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 fick’s laws de Broglie’s Hypothesis schrödinger’s Equation Matter-Wave
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The San Francisco Peace Treaty and the Problems Regarding Japan’s Exemption from Blame for the Colonization of Korea
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作者 YI Tae-Jin 《Cultural and Religious Studies》 2018年第1期33-50,共18页
The 1951 San Francisco Peace Treaty was the one and only international opportunity that would have allowed demanding for Japan’s responsibility of the colonization of Korea.However,the United States did not demand of... The 1951 San Francisco Peace Treaty was the one and only international opportunity that would have allowed demanding for Japan’s responsibility of the colonization of Korea.However,the United States did not demand of such to be done.Soon,Korea and Japan resumed their diplomatic relationship and had their first summit in 1952.After numerous negotiations,finally in 1965,the“Korea-Japan Treaty”was agreed upon.Even in this treaty,the interpretation of the colonization was different for both countries and ultimately resulted as an unresolved issue.This is because of the Japanese dependence to the San Francisco Peace Treaty.On the other hand,the League of Nations,founded in 1920,believed that the systematization of international law was vital to keeping international peace.Therefore,they put much effort in and successfully carried out the codification of international law.The“Report on the law of Treaties”which was completed in 1935,noted that the“1905 Protectorate Treaty”,which was the ultimate treaty that led to Korea being annexed by the Japanese,was one of the three treaties that had no effective standing.This decision was carried out to the International Law Commission of the United Nations in 1963 and became a Resolution after being submitted to the General Assembly in the end of the same year.Using the decisions of the League of Nations and the United Nations as evidence,this paper critically reviews the San Francisco Peace Treaty’s lack of reviewing the Japanese responsibility of the colonization of Korea. 展开更多
关键词 Protectorate TREATY of November 1905 International PEACE activists in 1900s The second Hague PEACE Conference William T.stead FRANCIs Rey James Garner Manley O.Hudson Harvard Draft Convention on the law of Treaties
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冻融-干湿作用下装配式结构节点部位的氯离子传输特性 被引量:1
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作者 包龙生 赵家康 +2 位作者 李练武 包宇扬 杨宇豪 《沈阳建筑大学学报(自然科学版)》 CAS 北大核心 2023年第2期271-277,共7页
目的 研究冻融-干湿循环作用下装配式混凝土结构节点部位的氯离子传输特性,为北方寒区装配式结构的发展提供理论基础。方法 在Fick第二定律的基础上推导氯离子在扩散和冻融作用下的偏微分方程,建立数值模型模拟冻融与氯盐干湿侵蚀交替... 目的 研究冻融-干湿循环作用下装配式混凝土结构节点部位的氯离子传输特性,为北方寒区装配式结构的发展提供理论基础。方法 在Fick第二定律的基础上推导氯离子在扩散和冻融作用下的偏微分方程,建立数值模型模拟冻融与氯盐干湿侵蚀交替作用下氯离子在装配式混凝土结构节点部位的传输过程。结果 在冻融-干湿循环作用下氯离子逐渐向混凝土内部扩散,随着侵蚀深度的增加,氯离子质量分数逐渐降低;在侵蚀深度10 mm处,冻融-干湿循环50次后的氯离子质量分数为0.246%,可以发现经历100次、150次、200次、250次、300次循环后,节点部位氯离子质量分数分别较经历50次循环增加了66.3%、99.2%、134.6%、164.2%、173.6%。结论 节点与其他部位相比受到氯离子的侵蚀作用更强;随着冻融-干湿循环次数的增加,氯离子质量分数增速放缓,各部位冻融破坏程度均增加。 展开更多
关键词 装配式混凝土结构 节点 干湿循环 冻融循环 氯离子 fick第二定律
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基于侵蚀扩散模型的混凝土硫酸根离子传输模拟
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作者 甘磊 陈官运 +1 位作者 沈振中 张文兵 《混凝土》 CAS 北大核心 2023年第5期39-43,共5页
探讨盐湖、盐渍土地区混凝土内硫酸根离子(SO_(4)^(2-))侵蚀问题,基于Fick第二定律,考虑扩散系数随混凝土孔隙率及曲折度变化,建立受侵蚀混凝土硫酸根离子侵蚀扩散模型,结合COMSOL Multiphysics软件仿真分析不同溶度SO_(4)^(2-)溶液浸... 探讨盐湖、盐渍土地区混凝土内硫酸根离子(SO_(4)^(2-))侵蚀问题,基于Fick第二定律,考虑扩散系数随混凝土孔隙率及曲折度变化,建立受侵蚀混凝土硫酸根离子侵蚀扩散模型,结合COMSOL Multiphysics软件仿真分析不同溶度SO_(4)^(2-)溶液浸泡条件下混凝土内SO_(4)^(2-)与铝酸钙类物质(CA)分布演化规律。结果表明:受侵蚀混凝土内SO_(4)^(2-)分布数值结果与试验值吻合较好;溶液浓度越高SO_(4)^(2-)扩散速度越快;相同侵蚀时间下SO_(4)^(2-)浓度与侵蚀深度呈负指数关系,CA含量由表及里变化,侵蚀表面CA含量最少;相同侵蚀深度下SO_(4)^(2-)浓度随侵蚀时间增加呈S型增长趋势,而CA含量则显著减小。 展开更多
关键词 混凝土 硫酸盐侵蚀 fick定律 扩散 数值模拟
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基于菲克第二定律的再生沥青中新旧沥青扩散融合研究
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作者 田小革 姚世林 +2 位作者 卢雪蓉 窦文利 昶慧芹 《重庆交通大学学报(自然科学版)》 CAS CSCD 北大核心 2023年第11期21-27,共7页
为了研究不同扩散时间、温度下新旧沥青扩散融合程度,制备了直径为25 mm,厚度为2 mm的老化沥青与新沥青双层沥青试样进行动态剪切流变试验;采用复数剪切模量G*作为双层沥青试样性能的表征参数,基于菲克第二定律理论计算了具有不同融合... 为了研究不同扩散时间、温度下新旧沥青扩散融合程度,制备了直径为25 mm,厚度为2 mm的老化沥青与新沥青双层沥青试样进行动态剪切流变试验;采用复数剪切模量G*作为双层沥青试样性能的表征参数,基于菲克第二定律理论计算了具有不同融合程度双层试样的G*理论值,从而采用迭代法并根据G*实测值计算出双层沥青试样中新旧沥青的融合程度;利用双因素方差分析评价了时间、温度对扩散融合程度的显著性。结果表明:复数剪切模量可以描述再生沥青中新旧沥青扩散融合且与新沥青掺量具有很好的线性关系,可作为性能变化的表征参数;70#基质沥青与90#基质沥青具有相同量级的扩散速率,均为10^(-7)左右,两种再生沥青的扩散速率随温度变化均呈指数增长;由双因素方差分析看出,扩散时间及温度对新旧沥青扩散融合程度都具有显著影响。 展开更多
关键词 道路工程 复数剪切模量 菲克第二定律 扩散模型 扩散系数
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早龄期受硫酸盐侵蚀下的混凝土分层腐蚀模型 被引量:3
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作者 管忠正 宋鹏飞 +3 位作者 王宁 王鹏 郇君虹 李勇 《科学技术与工程》 北大核心 2023年第6期2567-2572,共6页
为研究早龄期受硫酸盐侵蚀下混凝土的损伤劣化规律,采用压汞法(mercury intrusion porosimetry, MIP)测定了清水环境和硫酸盐环境下不同腐蚀龄期混凝土试样的孔隙率,利用分光光度法测定了混凝土中硫酸根离子的分布,并测试了不同腐蚀龄... 为研究早龄期受硫酸盐侵蚀下混凝土的损伤劣化规律,采用压汞法(mercury intrusion porosimetry, MIP)测定了清水环境和硫酸盐环境下不同腐蚀龄期混凝土试样的孔隙率,利用分光光度法测定了混凝土中硫酸根离子的分布,并测试了不同腐蚀龄期混凝土的超声波声速值。结果表明:清水组中混凝土的孔隙率先降低后逐渐趋于一个定值,硫酸钠溶液中混凝土的孔隙率则先降低后增加;混凝土超声波声速值的变化规律与孔隙率的变化规律呈负相关性。最后,结合硫酸根离子的分布规律和Fick第二定律,建立了腐蚀混凝土分层理论计算模型,并利用混凝土密实速率系数评估了混凝土的损伤劣化进程。 展开更多
关键词 混凝土 硫酸盐 超声波声速值 fick第二定律 分层理论计算模型
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