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Soil remediation potential of illite and Na-MMT for As and H_(3)AsO_(3) adsorption:Insights of ab initio calculations
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作者 LIU Zi-rou XU Xin-hang +2 位作者 ARMAGHANI Danial Jahed SPAGNOLI Dino QI Chong-chong 《Journal of Central South University》 2025年第5期1822-1837,共16页
Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium ... Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium montmorillonite(Na-MMT)(001)surfaces was investigated using first-principles calculations in this study,especially As atom and H_(3)AsO_(3) molecule.The adsorption energies of the As atom were−1.94 eV on the illite(001)and−0.56 eV on the Na-MMT(001),whereas,the adsorption energies of the H_(3)AsO_(3) molecule were−1.40 eV on illite(001)and−1.01 eV on Na-MMT(001).The above results indicate that the adsorption was more energetically favorable on illite(001).Additionally,compared to Na-MMT(001),there were more significant interactions between the atoms/molecules on the illite(001).After As atom and H_(3)AsO_(3) molecule adsorption,the electrons were transferred from mineral surface atoms to the adsorbates on both illite(001)and Na-MMT(001)surfaces.Moreover,the adsorption of As atom on illite(001)and Na-MMT(001)surfaces were more energy favorable compared to Hg,Cd,and Cr atoms.Overall,this work provides new insights into the adsorption behavior of As atoms and As molecules on illite and Na-MMT.The results indicate that illite rich soils are more prone to contamination by arsenic compared to soils primarily composed of Na-MMT minerals. 展开更多
关键词 soil contamination clay minerals ADSORPTION ab initio calculation ARSENIC
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Application of gurney and flight of fragment calculations for water jet velocities in explosive applications
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作者 Rachel L.Bauer Tate B.Friedrich Catherine E.Johnson 《Defence Technology(防务技术)》 2025年第7期68-78,共11页
This study investigates the application of Gurney and flight of fragment equations,typically used to predict metal fragment velocities,in modeling the water jet behavior.Three shotgun cartridge sizes were used as the ... This study investigates the application of Gurney and flight of fragment equations,typically used to predict metal fragment velocities,in modeling the water jet behavior.Three shotgun cartridge sizes were used as the energy source:2.59 g,5.83 g,and 7.13 g.Two configurations were tested:standard(full-barrel water load)and"negative 8"(partial water load).High-speed footage captured water column velocities,and Gurney models,including infinitely tamped and open-faced configurations,combined with the flight of fragment model were used to assess prediction accuracy.Results showed charge strength significantly affects water column velocity,with higher strengths yielding greater stability and velocity retention over distance.The infinitely tamped Gurney model closely predicted experimental velocities,deviating by as little as 1.4%for standard charges and 2.8% for negative 8 charges.Additionally,interesting dynamics such as a 1-2°rise in jet height and the rear overtaking the front was observed.These findings have significant implications for optimizing PAN disruptors and enhancing performance in high-velocity fluid applications and explosive breaching systems. 展开更多
关键词 Gurney calculations Water driven projectile Flight of fragment Incompressible fluid dynamics Optical velocity measurement
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High-resolution algorithm based on temporal-spatial extrapolation 被引量:3
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作者 Xueya Yang Baixiao Chen Feilin Qi 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第1期9-15,共7页
To enhance the resolution of parameter estimation with limited samples received by a short passive array, an iterative nonparametric algorithm for estimating the frequencies and direction-of-arrivals (DOAs) of signa... To enhance the resolution of parameter estimation with limited samples received by a short passive array, an iterative nonparametric algorithm for estimating the frequencies and direction-of-arrivals (DOAs) of signals is proposed. The cost function is constructed using 12-norm Gaussian entropy combined with an additional constraint, 12-norm constraint or linear constraint. By minimizing the cost functions in the temporal and the spatial dimensions using corresponding iteration algorithms respectively, the sparse discrete Fourier transforms (DFTs) of temporal and spatial samples are obtained to represent the extrapolated sequences with much larger sizes than the original samples. Then frequency and angle estimates are obtained by performing the traditional simple methods on the extrapolated sequences. It is shown that the proposed algorithm offers increased resolution and significantly reduced sidelobes compared with the periodogram and beamforming based methods. And it achieves high precision compared with the high-resolution method with lower computational burden. Some numerical simulations and real data processing results are presented to verify the effectiveness of the method. 展开更多
关键词 temporal-spatial extrapolation frequency estimation DIRECTION-OF-ARRIVAL discrete Fourier transform.
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Temporal-spatial cross-correlation analysis of non-stationary near-surface wind speed time series 被引量:3
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作者 ZENG Ming LI Jing-hai +1 位作者 MENG Qing-hao ZHANG Xiao-nei 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第3期692-698,共7页
Temporal-spatial cross-correlation analysis of non-stationary wind speed time series plays a crucial role in wind field reconstruction as well as in wind pattern recognition.Firstly,the near-surface wind speed time se... Temporal-spatial cross-correlation analysis of non-stationary wind speed time series plays a crucial role in wind field reconstruction as well as in wind pattern recognition.Firstly,the near-surface wind speed time series recorded at different locations are studied using the detrended fluctuation analysis(DFA),and the corresponding scaling exponents are larger than 1.This indicates that all these wind speed time series have non-stationary characteristics.Secondly,concerning this special feature( i.e.,non-stationarity)of wind signals,a cross-correlation analysis method,namely detrended cross-correlation analysis(DCCA) coefficient,is employed to evaluate the temporal-spatial cross-correlations between non-stationary time series of different anemometer pairs.Finally,experiments on ten wind speed data synchronously collected by the ten anemometers with equidistant arrangement illustrate that the method of DCCA cross-correlation coefficient can accurately analyze full-scale temporal-spatial cross-correlation between non-stationary time series and also can easily identify the seasonal component,while three traditional cross-correlation techniques(i.e.,Pearson coefficient,cross-correlation function,and DCCA method) cannot give us these information directly. 展开更多
关键词 temporal-spatial cross-correlation near-surface wind speed time series detrended cross-correlation analysis (DCCA) cross-correlation coefficient Pearson coefficient cross-correlation function
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N-Calculator与NUFER耦合模型和组合预测法在食物氮足迹研究中的应用
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作者 乔森 赵骏廷 郑洪波 《安全与环境学报》 CAS CSCD 北大核心 2024年第2期778-786,共9页
为改善传统N-Calculator模型的局限性,加强食物氮足迹核算结果与环境影响的联系,提高活性氮管理预见性,将N-Calculator模型与食物系统养分流动(Nutrient Flows in Food Chains,Environment and Resources Use,NUFER)模型进行耦合,以估... 为改善传统N-Calculator模型的局限性,加强食物氮足迹核算结果与环境影响的联系,提高活性氮管理预见性,将N-Calculator模型与食物系统养分流动(Nutrient Flows in Food Chains,Environment and Resources Use,NUFER)模型进行耦合,以估算我国2001—2020年人均食物氮足迹,建立组合预测体系。结果显示:2001—2020年,我国人均食物氮足迹由16.04 kg N/a增至18.95 kg N/a;全国食物氮足迹由20.47 Mt N/a增至26.76 Mt N/a;居民饮食结构正由以植物源食物为主的低氮消费模式转向以动物源食物为主的高氮消费模式;食物生产过程产生的活性氮的最终归宿为大气(64.3%)、水体和深层土壤(35.7%);我国食物氮足迹与人均可支配收入、城市化率、动物源食物消费氮占比呈正相关性,与恩格尔系数呈负相关性;未来10 a我国人均食物氮足迹呈增长趋势,预测结果显示年均增幅为0.16 kg N/a。 展开更多
关键词 环境学 食物氮足迹 活性氮 N-calculator模型 NUFER模型 组合预测模型
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Fuzzy recognition of missile borne multi-line array infrared detection based on size calculating 被引量:2
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作者 Bing-shan Lei Jing Li +1 位作者 Wei-na Hao Ke-ding Yan 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2021年第4期1135-1142,共8页
In order to improve the infrared detection and discrimination ability of the smart munition to the dynamic armor target under the complex background,the multi-line array infrared detection system is established based ... In order to improve the infrared detection and discrimination ability of the smart munition to the dynamic armor target under the complex background,the multi-line array infrared detection system is established based on the combination of the single unit infrared detector.The surface dimension features of ground armored targets are identified by size calculating solution algorithm.The signal response value and the value of size calculating are identified by the method of fuzzy recognition to make the fuzzy classification judgment for armored target.According to the characteristics of the target signal,a custom threshold de-noising function is proposed to solve the problem of signal preprocessing.The multi-line array infrared detection can complete the scanning detection in a large area in a short time with the characteristics of smart munition in the steady-state scanning stage.The method solves the disadvantages of wide scanning interval and low detection probability of single unit infrared detection.By reducing the scanning interval,the number of random rendezvous in the infrared feature area of the upper surface is increased,the accuracy of the size calculating is guaranteed.The experiments results show that in the fuzzy recognition method,the size calculating is introduced as the feature operator,which can improve the recognition ability of the ground armor target with different shape size. 展开更多
关键词 Multi-line array infrared detection Size calculating Custom threshold de-noising Fuzzy comprehensive discrimination algorithm
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An Iterative Calculating Method for Inbreeding and Relationship Coefficient
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作者 HANDan-dan SONGRen-xue 《Journal of Northeast Agricultural University(English Edition)》 CAS 2001年第1期19-22,共4页
The iterative formulas of inbreeding and relationship coefficients were put forward by using numerator elationship. It is suitable for any none - generation - overlap pedigree. The inbreeding and relationship coeffi- ... The iterative formulas of inbreeding and relationship coefficients were put forward by using numerator elationship. It is suitable for any none - generation - overlap pedigree. The inbreeding and relationship coeffi- ient of offsprings can be calculated by those of parents. The deducing process of numerator relationship is simple and clear comparing with path analysis. An example shows the usage of these formulas. 展开更多
关键词 Inbreeding coefficient relationship coefficient numerator relationship iterative calculating
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Study on Calculating Blockage Probability and Entry Angle Error of Intelligence Missile to Runway
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作者 崔乃刚 韦常柱 +1 位作者 郭继峰 赵彪 《Defence Technology(防务技术)》 SCIE EI CAS 2009年第4期261-266,共6页
The blockage effectiveness problem for the runway cut-blanked modes of intelligence missile is described using probability integral method,when entry angle error and open cabin position error exist. On the condition o... The blockage effectiveness problem for the runway cut-blanked modes of intelligence missile is described using probability integral method,when entry angle error and open cabin position error exist. On the condition of determined open cabin position error,the allowable range of entry angle error is inversely calculated with interdiction probability. The calculated results indicate that the method mentioned can estimate the intelligence missile interdiction efficiency to the runway and the range of entry angle error,which provides available basis for analyzing the intelligence missile attack assignment on the way. 展开更多
关键词 operational research intelligence missile blockage probability inverse calculation bullet-district
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Three-stage approach for dynamic traffic temporal-spatial model
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作者 陆化普 孙智源 屈闻聪 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第10期2728-2734,共7页
In order to describe the characteristics of dynamic traffic flow and improve the robustness of its multiple applications, a dynamic traffic temporal-spatial model(DTTS) is established. With consideration of the tempor... In order to describe the characteristics of dynamic traffic flow and improve the robustness of its multiple applications, a dynamic traffic temporal-spatial model(DTTS) is established. With consideration of the temporal correlation, spatial correlation and historical correlation, a basic DTTS model is built. And a three-stage approach is put forward for the simplification and calibration of the basic DTTS model. Through critical sections pre-selection and critical time pre-selection, the first stage reduces the variable number of the basic DTTS model. In the second stage, variable coefficient calibration is implemented based on basic model simplification and stepwise regression analysis. Aimed at dynamic noise estimation, the characteristics of noise are summarized and an extreme learning machine is presented in the third stage. A case study based on a real-world road network in Beijing, China, is carried out to test the efficiency and applicability of proposed DTTS model and the three-stage approach. 展开更多
关键词 dynamic traffic flow temporal-spatial model big-data driven
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Syntheses,crystal structures,and quantum chemistry calculation of two Ni(Ⅱ)coordination polymers 被引量:2
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作者 LI Xiumei HUANG Yanju +1 位作者 LIU Bo PAN Yaru 《无机化学学报》 SCIE CAS CSCD 北大核心 2024年第10期2031-2039,共9页
Two new coordination polymers,[Ni(Hpdc)(bib)(H_(2)O)]_(n)(1)and{[Ni(bib)_(3)](ClO_(4))_(2)}_(n)(2),were prepared by mixing Ni^(2+),3,5⁃pyrazoledicarboxylic acid(H3pdc)/p⁃nitrobenzoic acid and 1,4⁃bis(imidazol⁃1⁃ylmeth... Two new coordination polymers,[Ni(Hpdc)(bib)(H_(2)O)]_(n)(1)and{[Ni(bib)_(3)](ClO_(4))_(2)}_(n)(2),were prepared by mixing Ni^(2+),3,5⁃pyrazoledicarboxylic acid(H3pdc)/p⁃nitrobenzoic acid and 1,4⁃bis(imidazol⁃1⁃ylmethyl)butane(bib)by a hydrothermal method,respectively.X⁃ray crystallography reveals a 2D network constructed by six⁃coordinated Ni(Ⅱ)centers,bib,and Hpdc2-ligands in complex 1,while a 2D network is built by Ni(Ⅱ)and bib ligands in 2.Furthermore,the quantum⁃chemical calculations have been performed on‘molecular fragments’extracted from the crystal structure of 1 using the PBE0/LANL2DZ method in Gaussian 16 and the VASP program.CCDC:2343794,1;2343798,2. 展开更多
关键词 coordination polymer nickel(Ⅱ)complex crystal structure quantum⁃chemical calculation
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Coupling model for calculating prestress loss caused by relaxation loss,shrinkage,and creep of concrete
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作者 曹国辉 胡佳星 张锴 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第2期470-478,共9页
The calculation model for the relaxation loss of concrete mentioned in the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts(JTG D62—2004) was modified according to experime... The calculation model for the relaxation loss of concrete mentioned in the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts(JTG D62—2004) was modified according to experimental data. Time-varying relaxation loss was considered in the new model. Moreover, prestressed reinforcement with varying lengths(caused by the shrinkage and creep of concrete) might influence the final values and the time-varying function of the forecast relaxation loss. Hence, the effects of concrete shrinkage and creep were considered when calculating prestress loss, which reflected the coupling relation between these effects and relaxation loss in concrete. Hence, the forecast relaxation loss of prestressed reinforcement under the effects of different initial stress levels at any time point can be calculated using the modified model. To simplify the calculation, the integral expression of the model can be changed into an algebraic equation. The accuracy of the result is related to the division of the periods within the ending time of deriving the final value of the relaxation loss of prestressed reinforcement. When the time division is reasonable, result accuracy is high. The modified model works excellently according to the comparison of the test results. The calculation result of the modified model mainly reflects the prestress loss values of prestressed reinforcement at each time point, which confirms that adopting the finding in practical applications is reasonable. 展开更多
关键词 PRESTRESS relaxation loss shrinkage and creep theoretical analysis calculation model
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Calculating detonation performance of explosives by VLWR thermodynamics code introduced with universal VINET equation of state
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作者 Qin Liu Ying-liang Duan +3 位作者 Wei Cao Hong-hao Ma Xin-ping Long Yong Han 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第6期1041-1051,共11页
Thermodynamic calculation is the theoretical basis for the study of initiation and detonation,as well as the prerequisite for forecasting the detonation performance of unknown explosives.Based on the VLWR(Virial-Wu)th... Thermodynamic calculation is the theoretical basis for the study of initiation and detonation,as well as the prerequisite for forecasting the detonation performance of unknown explosives.Based on the VLWR(Virial-Wu)thermodynamic code,this paper introduced the universal solid equation of state(EOS)VINET.In order to truly reflect the compressibility of nanocarbon under the extremely high-temperature and high-pressure environment in detonation,an SVM(support vector machine)was utilized to optimize the input parameters of carbon.The detonation performance of several explosives with different densities was calculated by the optimized universal EOS,and the results show that the thermodynamic code coupled with the universal solid EOS VINET can predict the detonation performance parameters of explosives well.To investigate the application of the thermodynamic code with the improved VINET EOS in the working capacity of explosives,the interrelationship between pressure P-particle velocity u and pressure P-volume V were computed for the detonation products of TNT and HMX-based PBX(HMX:binder:insensitive agent=95:4.3:0.7)in the CJ isentropic state.A universal curve proposed by Cooper was used to compared the computed isentropic state,where the ratio of pressure to CJ state were plotted against the ratio of velocity to CJ state.The parameters of the JWL(Jones-Wilkins-Lee)EOS for detonation products were obtained by fitting the P-V curve.The cylinder tests of TNT and HMX-based PBX were numerically simulated using the LS-DYNA,it is verified that,within a certain range,the improved algorithm has superiority in describing the working capacity of explosives. 展开更多
关键词 Detonation performance Thermodynamic calculation VINET equation of state VLWR thermodynamics Code Support vector machine Cylinder test
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The Minimum Rotor Rotation Angle for Calculating On-Load Electromotive Force Waveform of Synchronous Generators
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作者 XIAYonghong WANG Shanming +1 位作者 HUANG Shaogang QIU Arui 《中国电机工程学报》 EI CSCD 北大核心 2012年第30期I0013-I0013,15,共1页
为了快速计算同步发电机负载运行时的稳态性能,希望在转子相对定子旋转的角度尽可能小的情况下就能够准确得到电枢绕组电动势波形。根据电机理论,针对分数槽绕组同步发电机负载运行时的气隙磁通密度进行分析,得到了准确计算电枢绕组电... 为了快速计算同步发电机负载运行时的稳态性能,希望在转子相对定子旋转的角度尽可能小的情况下就能够准确得到电枢绕组电动势波形。根据电机理论,针对分数槽绕组同步发电机负载运行时的气隙磁通密度进行分析,得到了准确计算电枢绕组电动势波形的转子最小旋转角。应用有限元法计算最小旋转角范围内定、转子不同位置下的电磁场,通过对电磁场计算结果进行后处理,得到了定子每个齿磁通在一个或者多个周期的变化波形,从而快速计算电枢绕组电动势波形。对两台不同电枢绕组形式的永磁同步发电机负载电动势波形进行了计算,通过对计算结果进行比较,验证了方法的正确性。在一台电机上进行了实验,计算结果和实验结果较吻合。该方法具有计算准确以及计算量小的优点。 展开更多
关键词 同步发电机 角度计算 旋转角度 电动势 波形 转子 空载 负载特性
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计及铁心非线性的变压器空间动态磁场加速计算方法 被引量:1
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作者 司马文霞 孙佳琪 +3 位作者 杨鸣 邹德旭 彭庆军 王劲松 《电工技术学报》 北大核心 2025年第5期1559-1574,共16页
快速获得变压器空间磁场动态分布是构建变压器数字孪生体的基础之一,然而现有快速计算方法难以快速、准确地获得铁心饱和工况下的磁场分布特性。因此,该文提出了计及铁心非线性的变压器空间动态磁场加速计算方法。首先,构建变压器电磁... 快速获得变压器空间磁场动态分布是构建变压器数字孪生体的基础之一,然而现有快速计算方法难以快速、准确地获得铁心饱和工况下的磁场分布特性。因此,该文提出了计及铁心非线性的变压器空间动态磁场加速计算方法。首先,构建变压器电磁场路耦合仿真模型,对关键变量进行参数化扫描,仿真获得不同非线性工况下的大量磁场数据,构建涉及铁心非线性工况的主磁通和漏磁通数据集;其次,提出融合卷积神经网络(CNN)和长短期记忆网络(LSTM)的双分支深度学习模型,训练提取磁场数据的空间和时间特征,解决主、漏磁通差异大造成的模型训练难题;最后,利用模型获得输入电压、电流与内部空间磁场分布的非线性映射关系,实现空间动态磁场的加速计算,为变压器数字孪生体的构建提供了快速获得磁场数据的方法。 展开更多
关键词 非线性 卷积神经网络 长短期记忆网络 磁场 加速计算
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RMC在“华龙一号”堆内屏蔽计算中的应用研究
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作者 应栋川 肖锋 +3 位作者 唐松乾 谭怡 田超 尚晓通 《核科学与工程》 北大核心 2025年第3期395-399,共5页
面对国外主流蒙特卡罗分析程序对我国技术封锁的现状,针对核电厂反应堆屏蔽设计和高精度屏蔽计算分析的刚性需求,中国核动力研究设计院与清华大学在反应堆用蒙特卡罗模拟程序(RMC)已有堆物理计算分析功能的基础上,联合开发了屏蔽计算功... 面对国外主流蒙特卡罗分析程序对我国技术封锁的现状,针对核电厂反应堆屏蔽设计和高精度屏蔽计算分析的刚性需求,中国核动力研究设计院与清华大学在反应堆用蒙特卡罗模拟程序(RMC)已有堆物理计算分析功能的基础上,联合开发了屏蔽计算功能,并通过系列算例验证程序的正确性和有效性。然而,已有验证算例仍在几何尺度、几何和材料构成上相对简单,RMC面对大尺度复杂几何和材料构成的实际工程屏蔽计算问题的应用能力仍待检验。为检验RMC屏蔽计算功能在核电厂实际工程问题中的计算分析能力,以“华龙一号”为应用对象,采用RMC程序充分模拟了中子和γ射线在反应堆内的耦合输运过程,并将计算结果与国际通用程序蒙特卡罗N粒子输运代码(MCNP)进行了对比,屏蔽计算结果符合良好,初步验证了RMC程序屏蔽计算结果的正确性及应用于核电厂反应堆堆内屏蔽计算分析的有效性。 展开更多
关键词 “华龙一号” 屏蔽计算 RMC
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UHPC免拆模板钢筋混凝土柱抗震性能参数分析及承载力计算 被引量:1
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作者 王朋 尤学辉 +3 位作者 史庆轩 陶毅 戎翀 黄杰 《建筑科学与工程学报》 北大核心 2025年第1期41-50,共10页
为研究UHPC免拆模板钢筋混凝土柱在不同参数影响下的抗震性能,基于ABAQUS软件中混凝土塑性损伤(CDP)模型,考虑模板与后浇混凝土的界面接触滑移建立了数值分析模型;讨论了轴压比、普通混凝土强度、配筋率和模板厚度等参数对UHPC免拆模板... 为研究UHPC免拆模板钢筋混凝土柱在不同参数影响下的抗震性能,基于ABAQUS软件中混凝土塑性损伤(CDP)模型,考虑模板与后浇混凝土的界面接触滑移建立了数值分析模型;讨论了轴压比、普通混凝土强度、配筋率和模板厚度等参数对UHPC免拆模板-RC柱承载力和延性的影响;基于平截面假定,给出了UHPC免拆模板-RC柱的承载力计算公式。结果表明:建立的有限元模型能较好地模拟试件的承载力、骨架曲线和混凝土损伤情况;随着轴压比的增大,试件的承载力和延性均先增大后减小,轴压比为0.7时承载力和延性均最高;随着混凝土强度的提高,试件的承载力逐渐增大,但增长幅度却逐渐降低;提高配筋率可以提高试件的承载力,但对延性影响不大;模板的厚度对试件的承载力和延性影响显著,当模板厚度从10 mm增加到25 mm时,试件的承载力提高了24.1%,但其延性降低了43.8%,在保证试件拥有足够的承载力和变形能力下,建议UHPC模板厚度选择15~20 mm;基于平截面假定得到的承载力计算方法可以很好地预测试件的承载能力,计算值与模拟值(试验值)的比值均值为0.97,标准差为0.04。 展开更多
关键词 UHPC免拆模板 钢筋混凝土柱 抗震性能 数值模拟 承载力计算
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长时间跨度下中国出生人口数量模拟测算研究 被引量:1
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作者 胡耀岭 荀月康 原新 《人口学刊》 北大核心 2025年第1期1-15,共15页
在长时间跨度下,生育模式不变假设将不再成立。本文在研究方法上摒弃传统的总和生育率法,拓展真实队列年龄别生育率估算方法,应用历次全国人口普查数据和抽样调查数据,间接估计相关出生队列育龄妇女年龄别生育率,采用人口间接估计技术,... 在长时间跨度下,生育模式不变假设将不再成立。本文在研究方法上摒弃传统的总和生育率法,拓展真实队列年龄别生育率估算方法,应用历次全国人口普查数据和抽样调查数据,间接估计相关出生队列育龄妇女年龄别生育率,采用人口间接估计技术,测算1975-2085年出生队列女性人口的年龄别生育率及其在育龄期的人口规模,以及未来80年长时间跨度下的中国出生人口数量。考察分析不同生育水平下的未来出生人口数量变化情况,如果保持测算所得出生队列育龄妇女年龄别生育率,出生人口数量将从2024年的1 010万人震荡下降到2050年的944万人,之后快速降至2100年的495万人;如果出生队列生育率保持1.5不变,2047年之前的出生人口数量处于1 100万人以上,之后快速下降至2100年的600万人;如果出生队列生育率保持1.8不变,2045年之前的出生人口数量处于1 400万人以上,2100年时的出生人口数量保持在1 000万人以上;如果出生队列生育率保持更替水平2.1不变,2024-2100年出生人口数量稳定保持在1 600万人以上。近期出生人口数量主要受到生育水平偏低的影响,中远期出生人口数量不仅受到生育水平偏低的影响,还会因近期出生人口数量下降而使中远期育龄妇女规模进一步减少,进而引致中远期出生人口数量下降速度更快。同时,本文还分析了保持一定出生人口数量所需要的生育水平,如果出生人口数量保持1 000万人不变,需要出生队列生育率从2024年的1.137快速增至2069年的2.105,之后保持在更替水平2.1左右;如果出生人口数量保持1 500万人不变,需要出生队列生育率从2024年的1.705增至2056年的2.194,之后缓慢下降到更替水平2.1左右;如果出生人口数量保持2 000万人不变,需要出生队列生育率从2024年的2.274增至2048年的2.674,之后快速下降到更替水平2.1左右。近期加大生育政策激励力度,增强生育政策支持效果,保持尽量高的生育水平,可以缓解未来提升生育水平的政策调整压力,为未来增加出生人口数量预留空间和蓄积能量。2024-2050年是我国提升生育水平的重要窗口期,也是实现中长期人口发展战略目标的关键机遇期,建议国家充分把握生育政策激励的黄金阶段,采取更加积极的生育激励政策措施,为实现人口高质量发展奠定坚实基础。 展开更多
关键词 长时间跨度 出生人口数量 出生队列生育率 模拟测算
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基于CVT电路模型的谐波还原方法研究 被引量:1
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作者 郭树永 江海 +3 位作者 戴甲水 郝良收 胡广富 朱豪帅 《高压电器》 北大核心 2025年第1期129-135,共7页
电容式电压互感器(CVT)是电力系统中重要的电压状态监测设备,其在测量工频电压时具有较高精度。但是当电力系统中发生次同步谐振等复杂工况时,CVT中间变压器的铁心将会发生饱和,CVT的电压传输特性将会随铁心电感的改变而改变,进而导致CV... 电容式电压互感器(CVT)是电力系统中重要的电压状态监测设备,其在测量工频电压时具有较高精度。但是当电力系统中发生次同步谐振等复杂工况时,CVT中间变压器的铁心将会发生饱和,CVT的电压传输特性将会随铁心电感的改变而改变,进而导致CVT在测量谐波时的测量误差增大。现有的基于电压传输特性的谐波测量方法难以在电压传输特性发生变化时动态计算CVT谐波。因此,文中搭建了计及中间变压器铁心饱和特性和杂散电容的CVT电路模型,通过逆向求解该模型,实现谐波的精准还原,最后对35 kV CVT进行谐波仿真验证,结果表明,与传统电压传递系数法相比,文中提出的谐波还原方法将谐波分量误差由94.6%降至7.1%,能够准确地计算出中间变压器铁心处于非线性状态时一次侧电压的实际谐波分量。 展开更多
关键词 电容式电压互感器 谐波测量 逆向求解 杂散电容
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基于2D-3D电磁场-路耦合新计算方法的百万千瓦级半速汽轮发电机端部区域多物理场研究 被引量:1
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作者 韩继超 王昕宇 +1 位作者 邱家玉 戈宝军 《中国电机工程学报》 北大核心 2025年第1期217-227,I0018,共12页
核能相对于传统火电具有更加广阔的应用前景,发展高效安全的核电半速汽轮发电机是核电技术发展的关键。作为电力系统的核心装备,随着百万千瓦级核电半速汽轮发电机单机容量的不断提高,其端部区域损耗和发热问题日趋严重。为了提高核电... 核能相对于传统火电具有更加广阔的应用前景,发展高效安全的核电半速汽轮发电机是核电技术发展的关键。作为电力系统的核心装备,随着百万千瓦级核电半速汽轮发电机单机容量的不断提高,其端部区域损耗和发热问题日趋严重。为了提高核电半速汽轮发电机端部电磁场和损耗的计算精度,提出一种2D-3D电磁场-路耦合新计算方法,研究1 407 MV·A核电半速汽轮发电机端部区域内电磁场和端部构件损耗的分布规律,采用磁场储能法和解析法计算得到定子端部漏抗,将定子端部漏抗应用于核电半速汽轮发电机外电路中,对二维瞬态电磁场、三维端部瞬态电磁场以及负载外电路进行了耦合计算,考虑转子旋转、材料特性以及复杂端部构件实际尺寸等因素,研究核电半速汽轮发电机端部电磁场、端部构件磁密和涡流密度的分布情况,确定核电半速汽轮发电机端部构件的损耗。建立了核电半速汽轮发电机三维端部区域流固耦合模型,将新计算方法得到的端部结构件损耗值作为热源,流体网络计算得到端部区域入口速度和出口压力值作为边界条件,计算得到端部区域内复杂流体流动和端部构件温度的分布规律,并与实测值进行对比,验证了所提计算方法的可行性。 展开更多
关键词 半速汽轮发电机 新计算方法 端部电磁场 损耗 温度分布
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含氟芳香查尔酮衍生物的合成与三阶非线性光学性质
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作者 王桂林 郝建峰 +2 位作者 石玉芳 王迎进 赵明根 《应用化学》 北大核心 2025年第1期86-94,共9页
合成4种查尔酮衍生物:1-(2,3-二氟苯基)-3-(3-氯噻吩-2-基)-2-丙烯-1-酮(0208#)、1-(2,4-二氟苯基)-3-(5-苯基噻吩-2-基)-2-丙烯-1-酮(0809#)、1-(2,3-二氟苯基)-3-(5-苯基噻吩-2-基)-2-丙烯-1-酮(0808#)和1-(2,6-二氟苯基)-3-(5-苯基噻... 合成4种查尔酮衍生物:1-(2,3-二氟苯基)-3-(3-氯噻吩-2-基)-2-丙烯-1-酮(0208#)、1-(2,4-二氟苯基)-3-(5-苯基噻吩-2-基)-2-丙烯-1-酮(0809#)、1-(2,3-二氟苯基)-3-(5-苯基噻吩-2-基)-2-丙烯-1-酮(0808#)和1-(2,6-二氟苯基)-3-(5-苯基噻吩-2-基)-2-丙烯-1-酮(0812#)。通过核磁共振氢谱(1H NMR)和碳谱(13C NMR)、液相色谱-质谱联用质谱(LC-MS)、紫外-可见吸收光谱(UV-Vis)、荧光发射(EM)光谱和Z-扫描技术对化合物的结构和性质进行了表征。采用密度泛函理论方法计算获得了该4种化合物的最高占据分子轨道与最低空分子轨道能量和极化率,从轨道电子云图发现存在显著的分子内电荷转移现象。大π共轭和电荷转移的结构效应使这4种芳香基查尔酮衍生物表现出良好的三阶非线性光学性质。它们可作为非线性吸收(NLA)和激光防护候选材料,具有潜在应用前景。 展开更多
关键词 查尔酮衍生物 理论计算 光学性质
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