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电弧等离子体一维非定常数值模拟 被引量:3
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作者 刘东尧 周彦煌 《高压物理学报》 EI CAS CSCD 北大核心 2001年第4期249-253,共5页
通过对毛细管内等离子体工作过程的分析给出了电弧等离子体的一维非定常数学模型 ,以热力学参量描述了非理想条件下等离子体的状态方程和电导率计算方法。利用差分法求解该数学方程组 ,给出了毛细管内电弧等离子体特征参量在毛细管内沿... 通过对毛细管内等离子体工作过程的分析给出了电弧等离子体的一维非定常数学模型 ,以热力学参量描述了非理想条件下等离子体的状态方程和电导率计算方法。利用差分法求解该数学方程组 ,给出了毛细管内电弧等离子体特征参量在毛细管内沿轴向随时间的变化规律。对数值模拟结果作相应的分析 ,并将部分模拟结果与实验数据作了比较。 展开更多
关键词 电热发射 等离子体 数值模拟 一维非定常数学模型 毛细管
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到两定直线的距离之比为常数的点的轨迹 被引量:1
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作者 张会凌 《甘肃联合大学学报(自然科学版)》 1996年第1期6-9,共4页
本文讨论了三维空间中到两定直线的距离之比为常数的点的轨迹。文章就二定直线平行、相交和异面三种情况给出了轨迹表示的曲面类型,并把二维平面上对应的轨迹问题作为所得结果的特殊情形进行了处理。
关键词 轨迹 到两直线距离之比为常数 图形类型
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非定常喷嘴射流形状预测研究 被引量:4
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作者 韩凤琴 林志文 +1 位作者 肖业祥 久保田乔 《水电能源科学》 2005年第3期14-16,i003,共4页
在对射流进行非定常CFD解析的基础上,提出了射流直径的计算公式和射流形状的统计预测方法,并由时间平均的射流形状确定了缩流位置、膨胀率等用于设计的重要参数。
关键词 冲击式水轮机 定常数 射流 多相流 数值解析
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修正的Navier-Stokes方程的定常解
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作者 张克伟 《内蒙古大学学报(自然科学版)》 CAS CSCD 1995年第6期657-663,共7页
考虑于1968年作为粘性不可压缩流的一个数学模型提出的修正的Navier-Stokes方程的定常解的存在性,唯一性和吸引性.定常的修正的Navier-Stokes方程是满足一定的单调性条件的拟线性椭圆方程组.利用逼近... 考虑于1968年作为粘性不可压缩流的一个数学模型提出的修正的Navier-Stokes方程的定常解的存在性,唯一性和吸引性.定常的修正的Navier-Stokes方程是满足一定的单调性条件的拟线性椭圆方程组.利用逼近建立了一个一般的存在性定理,进而看到,如果或者椭圆性常数足够大,或者具适当大的单调性参数,或者外力相当小,则有唯一的定常解,最后,我们在类似(仅仅是类似!)于上述的条件下证明了所有的定常解的集合是极小的紧的不变的可吸引相空间中任何有界集的吸引子. 展开更多
关键词 定常数 存在性 唯一性 吸引性 N-S方程
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大气定常波传播的运动学特征的时空变化 被引量:1
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作者 吴国雄 陈彪 吴正贤 《气象学报》 CSCD 北大核心 1990年第1期36-45,共10页
利用时间平均全球大气环流资料,本文计算了纬向平均位涡的南北梯度的时空分布,以及波动水平传播的临界波数n_s,和垂直传播的临界波数K_c的时空分布。由此研究全球大气定常波传播的运动学特征及其年变化。
关键词 大气 定常数 传播 运动学 年变化
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CINRAD/SB雷达回波强度定标调校方法 被引量:33
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作者 潘新民 柴秀梅 +3 位作者 崔柄俭 黄跃青 王全周 徐俊领 《应用气象学报》 CSCD 北大核心 2010年第6期739-746,共8页
回波强度定标和调校方法是保障CINRAD/SB回波强度测量精度的关键技术,方法不当会导致回波强度测量误差增大,直接影响雷达定量估测降水产品的可靠性。为了满足回波强度测量误差在±1 dBZ范围内的技术要求,根据雷达气象方程,通过对CIN... 回波强度定标和调校方法是保障CINRAD/SB回波强度测量精度的关键技术,方法不当会导致回波强度测量误差增大,直接影响雷达定量估测降水产品的可靠性。为了满足回波强度测量误差在±1 dBZ范围内的技术要求,根据雷达气象方程,通过对CINRAD/SB接收机测试通道、主通道、天馈系统相关影响回波强度测量误差的因素进行分析,提出了从接收机动态范围和雷达参数调整、线性通道增益定标目标常数定标,到测试通道参数调整的回波强度定标工作流程。总结出以线性通道增益定标目标常数定标为基准,采用测试通道参数测量法或基准法调校,以保证发射功率和接收机动态范围变化导致的回波强度测量误差得到在线实时校正,提高了CINRAD/SB回波强度测量精度。从接收机测试通道、主通道、天馈系统及发射功率4个方面,给出了回波异常的分析和诊断流程。并提出在接收机保护器前端增加机外信号注入口和定标信号功率检测功能,以利于机内外回波强度定标对比校准和消除测试通道参数变化导致回波强度测量误差的建议。 展开更多
关键词 CINRAD/SB雷达 回波强度 测量误差 线性通道增益标目标常数
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时滞系统的滤波器时间常数自调整内模控制 被引量:9
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作者 陈娟 潘立登 曹柳林 《系统仿真学报》 CAS CSCD 北大核心 2006年第6期1630-1633,共4页
对于工业控制过程中的大时滞和时变系统,利用Smith内模控制原理设计方法,建立了滤波器时间常数λ的自整定方法,并建立了滤波器时间常数λ的模糊整定规则;通过在线调整滤波器时间常数λ来改善其闭环特性。仿真结果表明,对于在控制过程中... 对于工业控制过程中的大时滞和时变系统,利用Smith内模控制原理设计方法,建立了滤波器时间常数λ的自整定方法,并建立了滤波器时间常数λ的模糊整定规则;通过在线调整滤波器时间常数λ来改善其闭环特性。仿真结果表明,对于在控制过程中过程对象与过程模型失配时,通过内模控制器的滤波器时间常数λ自整定;既改善了系统的控制品质又能提高控制系统的鲁棒性。且易于工程实现。 展开更多
关键词 内模控制 模糊规则 时间常数 鲁棒性
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具Logistic增长项的极小趋化系统的稳定性分析
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作者 李忠芳 韩亚洲 《中国计量学院学报》 2015年第4期495-500,共6页
利用扰动分析给出极小趋化系统的线性化系统,然后通过分析各个模态的振幅的长时间行为给出常数定态解的稳定性分析.发现平凡定态解总是不稳定,非平凡常数定态解的稳定性依赖于趋化系数,即当趋敏效应较强时,所有常数定态解都不稳定,从而... 利用扰动分析给出极小趋化系统的线性化系统,然后通过分析各个模态的振幅的长时间行为给出常数定态解的稳定性分析.发现平凡定态解总是不稳定,非平凡常数定态解的稳定性依赖于趋化系数,即当趋敏效应较强时,所有常数定态解都不稳定,从而预测了非常数定态解的存在性.最后结合数值实例,验证了理论分析的结果,且预测了非常数定态解的稳定性. 展开更多
关键词 极小趋化系统 常数态解 性分析 数值仿真
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具有MICHAELIS-MENTEN饱和函数的趋化模型斑图分析 被引量:1
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作者 袁蕾 段震鸣 +1 位作者 许震宇 夏鹏 《湖南工业职业技术学院学报》 2023年第2期15-19,共5页
针对一类具有MICHAELIS-MENTEN饱和函数的趋化模型斑图存在性,利用偏微分方程线性稳定性理论,通过对模型的常数定态解进行稳定性研究,得到了模型斑图存在的条件。利用数值研究证明了非常数解的存在性,分析了模态与斑图解之间的关系,并... 针对一类具有MICHAELIS-MENTEN饱和函数的趋化模型斑图存在性,利用偏微分方程线性稳定性理论,通过对模型的常数定态解进行稳定性研究,得到了模型斑图存在的条件。利用数值研究证明了非常数解的存在性,分析了模态与斑图解之间的关系,并从数值上验证了该模型具有亚稳性结构。 展开更多
关键词 斑图 常数态解 饱和函数 趋化模型
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中国对OECD服装出口增长解析——CMS方法应用 被引量:1
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作者 陈红霞 顾庆良 《经济研究导刊》 2012年第34期183-186,共4页
运用定常数市场占有率法(CMS)解析中国对OECD服装出口增长中世界增长因素、产品、市场结构与竞争力因素的贡献和动态变化、研究发现中国服装出口增长主要来源于世界增长因素和竞争力因素,产品和市场结构因素贡献很小,在低成本优势逐渐... 运用定常数市场占有率法(CMS)解析中国对OECD服装出口增长中世界增长因素、产品、市场结构与竞争力因素的贡献和动态变化、研究发现中国服装出口增长主要来源于世界增长因素和竞争力因素,产品和市场结构因素贡献很小,在低成本优势逐渐减弱的现实下,中国必须优化出口结构,跳出传统低价竞争模式,转变增长方式。CMS法分析还揭示了MFA消亡和金融危机是全球服装贸易重大转折点,发达国家也能够从贸易自由化机制中受益。 展开更多
关键词 服装出口 贡献因素 定常数市场占有率
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直驱风力发电机翼型特性数值仿真 被引量:3
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作者 黄娜 关正伟 +1 位作者 党晓圆 李洁 《计算机仿真》 北大核心 2021年第10期124-127,132,共5页
目前的发电机翼型特性数值仿真方法中,由于对翼身的抖振非定常数的计算不足,影响最终结果的准确性,因此提出直驱风力发电机特性数值仿真方法研究。首先建立风力空气动力模型,作为仿真动力基础。其次确定风翼参数,计算翼身的抖振非定常数... 目前的发电机翼型特性数值仿真方法中,由于对翼身的抖振非定常数的计算不足,影响最终结果的准确性,因此提出直驱风力发电机特性数值仿真方法研究。首先建立风力空气动力模型,作为仿真动力基础。其次确定风翼参数,计算翼身的抖振非定常数,最后在数值仿真中将翼型实现实体化生成,并根据风力空气动力模型实现数值仿真。为了验证设计的数值仿真方法的可行性,利用某地直驱风力发电机的相关参数,使用不同对比数值仿真方法和设计方法进行翼型特性数值仿真。实验结果证明设计方法的特性系数更接近实际值,在仿真中准确性较高。 展开更多
关键词 风力发电机 翼型特性 数值仿真 风力空气动力模型 抖振非定常数
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Preparation and Physicochemical Characterization of Quercetin-HP-β-CD Inclusion Complexes 被引量:3
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作者 杨照罡 古丽斯坦.阿吾提 +6 位作者 曹轶 朱静 伍博深 王坚成 吕万良 张烜 张强 《Journal of Chinese Pharmaceutical Sciences》 CAS 2006年第2期69-75,共7页
Aim To prepare and characterize the QURC-HP-β-CD inclusion complexes and investigate the thermodynamic parameters of the process. Methods QURC-HP-β-CD inclusion complexes were prepared by the grinding method. The eq... Aim To prepare and characterize the QURC-HP-β-CD inclusion complexes and investigate the thermodynamic parameters of the process. Methods QURC-HP-β-CD inclusion complexes were prepared by the grinding method. The equilibrium inclusion constants and thermodynamic parameters were determinated by phase solubility analysis. Dissolution tests were performed to study the dissolution rate of inclusion complexes. The formation of inclusion complexes was confirmed by differential scanning calorimetry ( DSC), infrared spectroscopy (IR) , powder X-ray diffractometry (PXRD) and scanning electron microscopy (SEM). Results The aqueous solubility of quercetin was greatly increased ( about 37 folds) by inclusion technique, and the initial dissolution rate was markedly improved (10 folds) in the first 5 min. The results of DSC and SEM photographs showed that quercetin crystal disappeared in inclusion complexes, which indicated the formation of new phase. FT-IR spectra showed that the carbonyl quercetin crystal grinding method. absorption band of quercetin was shifted. PXRD showed that the diffraction peak of disappeared. Conclusion QURC-HP-β-CD inclusion complexes are produced by the The solubility of quercetin is improved by the inclusion technique. 展开更多
关键词 QUERCETIN HYDROXYPROPYL-Β-CYCLODEXTRIN inclusion complex inclusion constant Phase behavior
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Determination of Stability Constants of Cadmium-Glycine Complexes by a Unified Treatment for Potentiometric and Polarographic Data
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作者 张建民 石秋芝 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2006年第2期164-168,共5页
The cadmium(Ⅱ)-glycine system was studied by the two experimental techniques, ion sensitive electrode (ISE) and differential pulse polarography (DPP), and the experimental data obtained were used by a unified m... The cadmium(Ⅱ)-glycine system was studied by the two experimental techniques, ion sensitive electrode (ISE) and differential pulse polarography (DPP), and the experimental data obtained were used by a unified mathematical treatment to calculate the complex stability constants. The combination of the two techniques is of many advantages as ISE can be performed at low [LT]:[MT] ratios and significantly higher [MT], whereas DPP could be used well at large [LT]:[MT] ratios and much smaller [MT]. This makes it possible to study a metal-ligand system in a relatively broader range of experimental conditions that, in turn, provides more information about the metakligand system of interest. Applying the unified mathematical treatment to the cadmium-glycine system, two new complexes MHL and ML2(OH) as well as three complexes ML, ML2 and ML3, reported in literatures, could be modeled and all their stability constants have been refined. 展开更多
关键词 Metal complex POLAROGRAPHY POTENTIOMETRY Stability constant
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运动粘度能力验证结果不满意的案例分析
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作者 吴瑾 《现代测量与实验室管理》 2010年第2期51-53,共3页
参加润滑油运动粘度能力验证时结果不满意,分析查找原因后,通过试验验证发现温度计插入恒温浴深度、粘度计检定常数对测定结果影响很大。
关键词 不满意 插入深度 定常数 Z比分数
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Pressure fluctuation and its influencing factors in circulating water pump 被引量:12
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作者 代翠 孔繁余 董亮 《Journal of Central South University》 SCIE EI CAS 2013年第1期149-155,共7页
In order to investigate the effect of sampling frequency and time on pressure fluctuations, the three-dimensional unsteady numerical simulations were conducted in a circulating water pump. Through comparison of turbul... In order to investigate the effect of sampling frequency and time on pressure fluctuations, the three-dimensional unsteady numerical simulations were conducted in a circulating water pump. Through comparison of turbulence models with hydraulic performance experiment, SST k-co model was confirmed to study the rational determination of sampling frequency and time better. The Fast Fourier Transform (FFT) technology was then adopted to process those fluctuating pressure signals obtained. On these bases, the characteristics of pressure fluctuations acting on the tongue were discussed. It is found that aliasing errors decrease at higher sampling frequency of 17 640 Hz, but not at a lower sampling frequency of 1 764 Hz. Correspondingly, an output frequency range ten-times wider is obtained at 17 640 Hz. Compared with 8R, when the sampling time is shorter, the amplitudes may be overvalued, and the frequencies and amplitudes of low-frequency fluctuations can not be well predicted. The frequencies at the tongue are in good agreement with the values calculated by formula and the frequency compositions less than the blade passing frequency are accurately predicted. 展开更多
关键词 circulating water pump turbulence model sampling frequency sampling time pressure fluctuation
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Unsteady Numerical Simulation of Flow around 2-D Circular Cylinder for High Reynolds Numbers 被引量:7
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作者 Yanhui Ai Dakui Feng +1 位作者 Hengkui Ye Lin Li 《Journal of Marine Science and Application》 2013年第2期180-184,共5页
In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54&#... In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54×106. The calculations were performed by means of solving the 2-D Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with a k-ε turbulence model. The calculated results, produced flow structure drag and lift coefficients, as well as Strouhal numbers. The findings were in good agreement with previous published data, which also supplied us with a good understanding of the flow across cylinders of different high Reynolds numbers. Meanwhile, an effective measure was presented to control the lift force on a cylinder, which points the way to decrease the vortex induced vibration of marine structure in future. 展开更多
关键词 circular cylinder vortex shedding high Reynolds number Strouhal numbers lift control measure marine structure unsteady numerical simulation
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Coherence of wind pressure on domes 被引量:3
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作者 尼尼昂 叶继红 《Journal of Southeast University(English Edition)》 EI CAS 2010年第1期100-106,共7页
The concept of the coherence function is adopted to find the wind pressure correlation of two points on domes of different rise-span ratios. The pressure measurements are made on the dome roof models by the wind tunne... The concept of the coherence function is adopted to find the wind pressure correlation of two points on domes of different rise-span ratios. The pressure measurements are made on the dome roof models by the wind tunnel test. The coherence functions for different separation distances at several directions of the domes from different wind directions are examined. The results show that there is a strong correlation for two adjacent points at low frequency, but not for non-adjacent points. The coherence of the wind pressure increases with the decrease in the separation distance. Moreover, the coherence of the wind pressure is in the strongest correlation on the along-wind direction at the same separation, but the lowest correlation is on the cross-wind direction. The detailed derivation of the proposed exponential coherence model of the wind pressure from experimental data is also discussed. It is found that the proposed exponential coherence model can be appropriate, especially, for small separations and the change in the directions on domes. Based on the quasi-steady theory, the relationship between the wind pressure and the wind velocity on the basis of the coherence model is also examined. The coherence observed between the wind pressure and the wind velocity is not adequately predicted by the quasi-steady theory. 展开更多
关键词 DOMES coherence of wind pressure exponential coherence model of wind pressure quasi-steady theory
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Stability constants of Sb^5+with Cl−and thermodynamics of Sb−S−Cl−H2O system involving complex behavior of Sb with Cl 被引量:1
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作者 Gang LI Yun-tao XIN +3 位作者 Xiao-dong Lü Qing-hua TIAN Kang YAN Long-gang YE 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第12期3379-3389,共11页
The stability constants of Sb^5+with Cl−as well as thermodynamics of the Sb−S−Cl−H2O system were calculated.The stability constants of Sb5+with Cl−were obtained by theoretical calculations of the absorbance of a Sb5+-... The stability constants of Sb^5+with Cl−as well as thermodynamics of the Sb−S−Cl−H2O system were calculated.The stability constants of Sb5+with Cl−were obtained by theoretical calculations of the absorbance of a Sb5+-containing solution at different Cl^−concentrations,which was detected by spectrophotometric analysis at certain wavelengths of light(380 nm).The logarithmic values versus 10 of stability constants of Sb^5+with Cl−were 1.795,3.150,4.191,4.955,5.427 and 5.511,respectively,and partly filled the data gaps in the hydrometallurgy of antimony.The presence and distribution of pentavalent antimony compounds under different conditions were analyzed based on equilibrium calculations.Thermodynamic equilibrium calculations were performed for Sb−S−Cl−H2O system,which included the complex behavior of Sb with Cl,and the equilibrium equations of related reactions in this system were integrated into the potential−pH diagram. 展开更多
关键词 complex behavior stability constant thermodynamics Sb−S−Cl−H2O system
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Method of Calculation of Stability Constants of Fulvic Complexes on the Example of Copper 被引量:1
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作者 Giorgi Makharadze Tamar Makharadze 《Journal of Chemistry and Chemical Engineering》 2014年第2期108-111,共4页
On the example of copper fulvate, it is discussed the method of calculation of stability constants of fulvic complexes. At pH = 8, the complex formation of copper(ll) ions with fulvic acids was studied by the solubi... On the example of copper fulvate, it is discussed the method of calculation of stability constants of fulvic complexes. At pH = 8, the complex formation of copper(ll) ions with fulvic acids was studied by the solubility method. Fulvic acids were separated from the river Mtkvari by the adsorption-chromotographic method. The charcoal (BAU, Russia) was used as a sorbent. The suspension of copper(If) hydroxide was used as the solid phase, on which was added the increasing quantity of standard solution of fulvic acids. In diluted solutions, at pH = 8 the dominant form of copper(lI) is copper dihydroxo complex Cu(OH)^zO. It was established that in the Cu(OH)2 (solid)-Cu(OH)^20 (solution)-FA^2-H20 system, dominates copper dyhydroxo fulvate complex with the structure 1:1, [Cu(OH)2FA]^2. The average stability constant of copper dyhydroxo fulvate complex was calculated based on experimental data fl [Cu(OH)2FAJ^2 = 4.5× l0^5. 展开更多
关键词 COPPER fulvic acids the average stability constant copper fulvate water.
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Experimental Study on Calculation of Hydro-Geological Parameters for Unsteady Flow 被引量:1
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作者 熊春宝 陈雯 叶作安 《Transactions of Tianjin University》 EI CAS 2013年第5期351-355,共5页
After the linear analytical method of unsteady flow theory is further improved,an innovative and faster algorithm is introduced.The water storage in a confined aquifer is derived from the water transmissivity coeffici... After the linear analytical method of unsteady flow theory is further improved,an innovative and faster algorithm is introduced.The water storage in a confined aquifer is derived from the water transmissivity coefficient and the water-pressure conductivity coefficient.The water transmissivity coefficient is approximated by a Taylorseries expansion of drawdown,and the water-pressure conductivity coefficient is obtained by the average drawdown.In this algorithm,the distance of the observation points from the pumping well must be short.When the distance is as short as the radius of the main pumping well,the data of the drawdown difference between the sidewall and the center of pumping well are difficult to measure,but the same results can be achieved based on the assumption that the drawdown difference approximates to the drawdown of the observation wells at a radial distance from the pumping well according to the algorithm.Without the help of charts,this algorithm is more concise and efficient,which has been verified by the test of water pumping project in Tianjin Binhai International Airport. 展开更多
关键词 pumping test unsteady flow theory improved linear analytical method hydro-geological parameter
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