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混凝土暴露试验的稳定时长与试验分析方法 被引量:1
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作者 杨绿峰 龙凤波 +1 位作者 孙继玮 陈俊武 《材料导报》 EI CSCD 北大核心 2024年第2期132-138,共7页
混凝土自然暴露试验通常用于研究混凝土的氯离子扩散系数,但需要选择合适的分析方法,并确定稳定暴露时长。为此,首先系统研究混凝土的氯离子瞬时扩散和平均扩散理论,明确扩散方程中不同参数的时变特性,揭示了瞬时扩散解析解在分析混凝... 混凝土自然暴露试验通常用于研究混凝土的氯离子扩散系数,但需要选择合适的分析方法,并确定稳定暴露时长。为此,首先系统研究混凝土的氯离子瞬时扩散和平均扩散理论,明确扩散方程中不同参数的时变特性,揭示了瞬时扩散解析解在分析混凝土中氯离子扩散过程和浓度分布时与平均扩散解析解等价。然后,引入随机数模拟混凝土取样误差,利用蒙特卡洛法分析氯盐环境下混凝土暴露时长、取样误差以及不同回归分析方法对扩散系数计算结果的影响,研究表明瞬时扩散解用于混凝土自然暴露试验分析时容易受到参数迭代初值的影响,导致初始扩散系数计算结果不稳定,而平均扩散解可以避免该问题,因而平均扩散解更适合于混凝土自然暴露试验数据的回归分析。在此基础上,研究确定了不同取样误差下的混凝土稳定暴露时长。最后,通过工程实例分析验证了回归分析方法以及稳定暴露时长在氯盐环境下混凝土自然暴露试验数据分析中的合理性和必要性。 展开更多
关键词 混凝土 氯离子 扩散方程 初始扩散系数 稳定暴露时长
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粉尘测量仪检定准确性和效率的主要影响因素初探
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作者 肖承川 张雯 +3 位作者 李思梦 邱婷婷 曾令平 卿永泉 《计量与测试技术》 2024年第3期57-60,共4页
粉尘测量仪作为监测环境空气受颗粒物污染程度的重要工具,被广泛用于疾控、环保和工矿企业中。为保证其量值的准确可靠,需定期进行计量检定或校准。为了提高其检定或校准的准确性和效率,本文探讨了几个主要影响因素,如检定中仪器放置方... 粉尘测量仪作为监测环境空气受颗粒物污染程度的重要工具,被广泛用于疾控、环保和工矿企业中。为保证其量值的准确可靠,需定期进行计量检定或校准。为了提高其检定或校准的准确性和效率,本文探讨了几个主要影响因素,如检定中仪器放置方式、被检仪器系数设置方式、尘棒质量、发尘控制方式、粉尘浓度稳定时长等。 展开更多
关键词 粉尘测量仪 放置方式 仪器系数设置 尘棒质量 发尘控制方式 稳定时长
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The Constitution and Working Mechanism of the Fast Fashion Enterprise Financial Competitiveness
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作者 YANG Guang 《International English Education Research》 2015年第10期81-83,共3页
With the Pearson Correlation Coefficient measurement method, this paper studies the correlation between the various elements influencing the financial competitiveness of the fast fashion enterprieses and the long-term... With the Pearson Correlation Coefficient measurement method, this paper studies the correlation between the various elements influencing the financial competitiveness of the fast fashion enterprieses and the long-term financial stability, which shows that the financial resilience has the biggest correlation with the long-term financial stability, which is followed in sequence by financial management capacity, financial resources capacity, financial performance capacity, and financial activity capacity. This is due to the fact that such factors as financial solvency, financial operations, profitability, growth capacity and the ability to generate cash exert effect upon the long-term stability of the financial competitiveness. 展开更多
关键词 fast fashion financial competitiveness financial resilience
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ALMOST SURE AND MOMENT EXPONENTIAL STABILITY OF PREDICTOR-CORRECTOR METHODS FOR STOCHASTIC DIFFERENTIAL EQUATIONS 被引量:4
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作者 Yuanling NIU Chengjian ZHANG 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2012年第4期736-743,共8页
This paper deals with almost sure and moment exponential stability of a class of predictor- corrector methods applied to the stochastic differential equations of Ito-type. Stability criteria for this type of methods a... This paper deals with almost sure and moment exponential stability of a class of predictor- corrector methods applied to the stochastic differential equations of Ito-type. Stability criteria for this type of methods are derived. The methods are shown to maintain almost sure and moment exponential stability for all sufficiently small timesteps under appropriate conditions. A numerical experiment further testifies these theoretical results. 展开更多
关键词 Almost sure stability moment exponential stability numerical experiment stochastic differential equations.
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QUALITATIVE ANALYSIS OF A STOCHASTIC PREDATOR-PREY SYSTEM WITH DISEASE IN THE PREDATOR 被引量:2
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作者 SHUANG LI XINAN ZHANG 《International Journal of Biomathematics》 2013年第1期115-127,共13页
A stochastic predator prey system with disease in the predator population is proposed, the existence of global positive solution is derived. When the white noise is small, there is a stationary distribution. In additi... A stochastic predator prey system with disease in the predator population is proposed, the existence of global positive solution is derived. When the white noise is small, there is a stationary distribution. In addition, conditions of global stability for the determin- istic system are also established from the above result. By Lyapunov function, the long time behavior of solution around the disease-free equilibrium of deterministic system is derived. These results mean that stochastic system has the similar property with the corresponding deterministic system. When the white noise is small, however, large envi- ronmental noise makes the result different. Finally, numerical simulations are carried out to support our findings. 展开更多
关键词 PREDATOR-PREY stochastic perturbation stationary distribution stability extinct.
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An unconditionally energy stable finite difference scheme for a stochastic Cahn-Hilliard equation 被引量:7
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作者 LI Xiao QIAO ZhongHua ZHANG Hui 《Science China Mathematics》 SCIE CSCD 2016年第9期1815-1834,共20页
In this work, the MMC-TDGL equation, a stochastic Cahn-Hilliard equation, is solved numerically by using the finite difference method in combination with a convex splitting technique of the energy functional.For the n... In this work, the MMC-TDGL equation, a stochastic Cahn-Hilliard equation, is solved numerically by using the finite difference method in combination with a convex splitting technique of the energy functional.For the non-stochastic case, we develop an unconditionally energy stable difference scheme which is proved to be uniquely solvable. For the stochastic case, by adopting the same splitting of the energy functional, we construct a similar and uniquely solvable difference scheme with the discretized stochastic term. The resulted schemes are nonlinear and solved by Newton iteration. For the long time simulation, an adaptive time stepping strategy is developed based on both first- and second-order derivatives of the energy. Numerical experiments are carried out to verify the energy stability, the efficiency of the adaptive time stepping and the effect of the stochastic term. 展开更多
关键词 Cahn-Hilliard equation stochastic term energy stability convex splitting adaptive time stepping
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DYNAMICS OF AN HIV-1 INFECTION MODEL WITH CELL-MEDIATED IMMUNE RESPONSE AND STOCHASTIC PERTURBATION 被引量:4
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作者 CHUNYAN JI DAQING JIANG 《International Journal of Biomathematics》 2012年第5期103-127,共25页
In this paper, we introduce the stochasticity into an HIV-1 infection model with cytotoxic T lymphocytes (CTLs) immune response via the technique of parameter perturbation. We show that there is a positive solution ... In this paper, we introduce the stochasticity into an HIV-1 infection model with cytotoxic T lymphocytes (CTLs) immune response via the technique of parameter perturbation. We show that there is a positive solution as desired in any population dynamics. Then we analyze the long time behavior of this model. We obtain a sufficient condition for the stochastic asymptotic stability in the large of the infection-free equilibrium and give the conditions for the solution fluctuating around the two infection equilibria (one without CTLs being activated and the other with). Finally, we make sinmlations to conform to our analytical results. 展开更多
关键词 HIV-1 infection the infection-free equilibrium the CTL^inactivated infectionequilibrium the interior equilibrium stochastic asymptotic stability in the large.
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