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非线性水平动量平流作用对热带气旋运动的影响 被引量:10
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作者 杨平章 贺海晏 《中山大学学报(自然科学版)》 CAS CSCD 1995年第1期82-89,共8页
本文将热带气旋视为与环境间有动量交换的系统,着重分析了非线性水平动量平流作用对热带气旋运动的影响,从理论上解释了一些热带气旋路径异常变化的原因。
关键词 热带气旋 非线性 水平动量 平流作用
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台风移动规律的研究 Ⅲ.台风与外界水平动量交换的影响 被引量:10
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作者 贺海晏 董惠菁 《热带气象学报》 CSCD 1995年第3期193-202,共10页
着重分析了流场半非对称台风的流入层和流出层与外界的水平动量交换影响台风移动的定性特征。结果表明,主要流入通道或主要流出通道位于台风右(左)侧时,有利于台风加速、左折(减速、右折);当主要流入通道或主要流出通道位于台风... 着重分析了流场半非对称台风的流入层和流出层与外界的水平动量交换影响台风移动的定性特征。结果表明,主要流入通道或主要流出通道位于台风右(左)侧时,有利于台风加速、左折(减速、右折);当主要流入通道或主要流出通道位于台风后部(前部)时,有利于台风加速、右折(减速、左折)。 展开更多
关键词 水平动量交换 台风 移动规律
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水平动量注入型等离子体合成射流激励器工作特性 被引量:1
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作者 张宇超 谭慧俊 +4 位作者 程林 何小明 黄河峡 庄逸 张悦 《气体物理》 2017年第6期9-17,共9页
等离子体合成射流控制技术因其具有不需要外部气源、工作频带宽、射流速度高、射流净质量通量为零、低功耗、激励器形式多样、环境适应性强等特点成为了目前针对高速流场主动流动控制技术中应用潜能大、有望实现实际工程应用突破的流动... 等离子体合成射流控制技术因其具有不需要外部气源、工作频带宽、射流速度高、射流净质量通量为零、低功耗、激励器形式多样、环境适应性强等特点成为了目前针对高速流场主动流动控制技术中应用潜能大、有望实现实际工程应用突破的流动控制装置.传统的等离子体激励器的出口多为垂直于流向或与流向成一定夹角故垂直于流向的动量分量会对激励器的流动控制能力产生影响.为增强流向动量注入能力拟设计一种新型的水平动量注入型等离子体合成射流激励器.主要内容有采用外部电路电参数测量与高速纹影技术对激励器常压下单周期工作特性与重频工作特性进行了初步研究.对水平动量注入型等离子体合成射流激励器的射流结构进行了分析探究了该激励器工作频率对射流流场的流场特性与控制能力的影响.最后在高速纹影测量的基础上开展了激励器高频工作时均出口动压的研究.实验表明水平动量注入型激励器单周期射流初始速度达到220 m/s单周期激波初始速度达到477 m/s.此外工作频率对于激励器的影响主要体现在对激励器控制范围的影响当激励器工作频率增高时在相同位置时激励器的动压输入能力下降. 展开更多
关键词 等离子体合成射流 水平动量输入 高速纹影 动压测量 高频放电
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Variation Dynamics of Total Nitrogen and Nicotine of Burley Tobacco at Various Growing Stages under Different Nitrogen Nutrition Levels 被引量:2
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作者 柴家荣 《Agricultural Science & Technology》 CAS 2012年第11期2327-2331,共5页
[Objective] This study aimed to investigate the variation dynamics of total nitrogen and nicotine of burtey tobacco at various growing stages under different ni- trogen nutrition levels to provide reference for optimi... [Objective] This study aimed to investigate the variation dynamics of total nitrogen and nicotine of burtey tobacco at various growing stages under different ni- trogen nutrition levels to provide reference for optimizing fertilization technologies for burley tobacco. [Method] Fresh burley tobacco leaves were collected at various growing stages and dried to measure the content of total nitrogen, protein and nico- tine by using INTEGRAL automated chemical analyzer and analyze the correlation with nitrogen application level. [Result] Regardless of the nitrogen application level, the content of total nitrogen and protein showed a downward trend since root ex- tending stage and reached the minimum at mature stage; the content of nicotine showed an upward trend since early vigorous growing stage and increased to the maximum at mature stage; the content of total nitrogen, protein and nicotine all in- creased after air curing; the content of total nitrogen, protein and nicotine showed positive correlation with nitrogen application level, while total nitrogen/nicotine was negatively correlated. The results indicate that nitrogen level is closely related to the total nitrogen and nicotine of burley tobacco at growing period and post-air curing, rational application of nitrogen is an important measure to regulate the content of total nitrogen and nicotine of tobacco. [Conclusion] This study provides scientific ba- sis for rational fertilization of burley tobacco. 展开更多
关键词 Burley tobacco Nitrogen nutrition Growth period Total nitrogen NICOTINE
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Role of Downward Momentum Transport in the Formation of Severe Surface Winds 被引量:3
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作者 LIU Xiang-E GUO Xue-Liang 《Atmospheric and Oceanic Science Letters》 2012年第5期379-383,共5页
The Weather Research and Forecasting (WRF) model was used to investigate the role of downward momentum transport in the formation of severe surface winds for a squall line on 3-4 June 2009 across regions of the Henan ... The Weather Research and Forecasting (WRF) model was used to investigate the role of downward momentum transport in the formation of severe surface winds for a squall line on 3-4 June 2009 across regions of the Henan and Shandong Provinces of China. The results show that there was a strong westerly jet belt with a wind speed greater than 30 m s 1 and a thickness of 5 km at an altitude of 11-16 km. The jet belt was accelerated, and it descended while the squall line convective system occurred. It was found that the appearance of strong negative perturbation pressure accompanied by the squall line caused the acceleration of the upper-level westerly jet and increased the horizontal wind speed by a maximum of 18%. Meanwhile, the negative buoyancy due to the loading, melting, and evaporation of cloud hydrometeors induced the downward momentum transport from the upper levels. The downward momentum transport contributed approximately 70% and the surface cold pool 30% to the formation of severe surface winds. 展开更多
关键词 downward momentum transport severe surface winds WRF model
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Exact Solution of D-Dimensional Klein-Gordon Oscillator with Minimal Length
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作者 Y.Chargui L.Chetouani A.Trabelsi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第2期231-236,共6页
Specific modifications of the usual canonical commutation relations between position and momentumoperators have been proposed in the literature in order to implement the idea of the existence of a minimal observablele... Specific modifications of the usual canonical commutation relations between position and momentumoperators have been proposed in the literature in order to implement the idea of the existence of a minimal observablelength. Here, we study a consequence of this proposal in relativistic quantum mechanics by solving in the momentumspace representation the Klein-Gordon oscillator in arbitrary dimensions. The exact bound states spectrum and thecorresponding momentum space wave function are obtained. Following Chang et al. (Phys. Rev. D 65 (2002) 125027),we discuss constraint that can be placed on the minimal length by measuring the energy levels of an electron in a penningtrap. 展开更多
关键词 Klein-Gordon oscillator minimal length energy spectrum
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A NOVEL METHOD FOR CALCULATING VERTICAL VELOCITY:A RELATIONSHIP BETWEEN HORIZONTAL VORTICITY AND VERTICAL MOVEMENT 被引量:7
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作者 丁治英 赵向军 +1 位作者 高松 罗亚丽 《Journal of Tropical Meteorology》 SCIE 2016年第2期208-219,共12页
The present work provides a novel method for calculating vertical velocity based on continuity equations in a pressure coordinate system.The method overcomes the disadvantage of accumulation of calculating errors of h... The present work provides a novel method for calculating vertical velocity based on continuity equations in a pressure coordinate system.The method overcomes the disadvantage of accumulation of calculating errors of horizontal divergence in current kinematics methods during the integration for calculating vertical velocity,and consequently avoids its subsequent correction.In addition,through modifications of the continuity equations,it shows that the vorticity of the vertical shear vector(VVSV) is proportional to-ω,the vertical velocity in p coordinates.Furthermore,if the change of ω in the horizontal direction is neglected,the vorticity of the horizontal vorticity vector is proportional to-ω.When ω is under a fluctuating state in the vertical direction,the updraft occurs when the vector of horizontal vorticity rotates counterclockwise;the downdraft occurs when rotating clockwise.The validation result indicates that the present method is generally better than the vertical velocity calculated by the ω equation using the wet Q-vector divergence as a forcing term,and the vertical velocity calculated by utilizing the kinematics method is followed by the O'Brien method for correction.The plus-minus sign of the vertical velocity obtained with this method is not correlated with the intensity of d BZ,but the absolute error increases when d BZ is >=40.This method demonstrates that it is a good reflection of the direction of the vertical velocity. 展开更多
关键词 horizontal vorticity vertical velocity continuity equation Q-vector vorticity of vertical shear vector
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Effect of Solving Models on Euler Vectors 被引量:1
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作者 Zhan Wei Wu Yanqiang +3 位作者 Ding Xiaoguang Wang Ziyan Liu Zhiguang Meng Xiangang 《Earthquake Research in China》 2014年第1期73-78,共6页
In the process of solving Euler vectors based on GNSS horizontal movement field,the number of estimated parameters can affect Euler vector results. This issue is analyzed through theoretical deduction and practical ex... In the process of solving Euler vectors based on GNSS horizontal movement field,the number of estimated parameters can affect Euler vector results. This issue is analyzed through theoretical deduction and practical example in this paper. Firstly,the difference between the results of Euler vectors in different solving models is deduced. Meanwhile, based on GNSS horizontal movement field in the Chinese mainland from 2004 to 2007,two common models( RRM and REHSM) are used to discuss the impact of solving models on Euler vectors and the follow-up study. The result shows that the maximum value of the difference in a block's entire rotation can reach 2. 6mm /a,and should not be ignored. Therefore,the results of horizontal movement are different using different kinematic block models,and this should be paid more attention in the analysis of crustal horizontal movement. 展开更多
关键词 GNSS horizontal movement field Euler vector Solving model STRAIN
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Liquid nitrogen level meter for high-temperature superconductor (HTS) 被引量:1
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作者 PARK Heecheol JEONG Hwanjun +3 位作者 LEE Changyeung KIM Purn CHO Jangwon KIM Seokho 《Journal of Central South University》 SCIE EI CAS 2012年第11期3100-3104,共5页
Many kinds of high temperature superconductor (HTS) power machines such as HTS cable, HTS fault current limitcr and HTS magnet are cooled by liquid nitrogen. The level of liquid nitrogen should be monitored and cont... Many kinds of high temperature superconductor (HTS) power machines such as HTS cable, HTS fault current limitcr and HTS magnet are cooled by liquid nitrogen. The level of liquid nitrogen should be monitored and controlled to ensure the thermal stability and the dielectric strength as well. To measure the level, capacitance method and differential pressure method are usually used. However, each method has installation difficulties and measurement errors for unsteady state operation with varying system pressure. A new liquid level meter using a 2G HTS conductor is described, which has similar structure with the liquid helium level meter with NbTi filament. The level meter is fabricated with a parallel connected heater, which helps the separation of the superconducting region and normal region, considering the critical temperature, large heat capacity of conductor and cooling characteristics. The level of liquid nitrogen can be obtained from the measured voltage signal along the 2G HTS conductor. Design, fabrication and test results of the new liquid nitrogen level meter are presented. 展开更多
关键词 high temperature superconductivity liquid nitrogen level meter QUENCH
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Non-invasive glucose measuring apparatus based on conservation of energy method 被引量:1
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作者 陈真诚 金星亮 +2 位作者 朱健铭 王弟亚 张婷婷 《Journal of Central South University》 SCIE EI CAS 2009年第6期982-986,共5页
A new non-invasive blood glucose measuring apparatus (NBGMA) made up of MSP430F149 SCM (single chip micyoco) was developed,which can measure blood glucose level (BGL) frequently,conveniently and painlessly. The hardwa... A new non-invasive blood glucose measuring apparatus (NBGMA) made up of MSP430F149 SCM (single chip micyoco) was developed,which can measure blood glucose level (BGL) frequently,conveniently and painlessly. The hardware and software of this apparatus were designed,and detecting algorithms based on conservation of energy method (COEM) were presented. According to the law of conservation of energy that the energy derived by human body equals energy consumed by metabolism,and the relationship between convection,evaporation,radiation and the BGL was established. The sensor module was designed. 20 healthy volunteers were involved in the clinical experiment. The BGL measured by an automatic biochemical analyzer (ABA) was set as the reference. Regression analysis was performed to compare the conservation of energy method with the biochemical method,using the 20 data points with blood glucose concentrations ranging from 680 to 1 100 mg/L. Reproducibility was measured for healthy fasting volunteers. The results show that the means of BGL detected by NBGMA and ANA are very close to each other,and the difference of standard deviation (SD) is 24.7 mg/L. The correlative coefficient is 0.807. The coefficient of variation (CV) is 4% at 921.6 mg/L. The resultant regression is evaluated by the Clarke error grid analysis (EGA) and all data points are included in the clinically acceptable regions (region A:100%,region B:0%). Accordingly,it is feasible to measure BGL with COEM. 展开更多
关键词 single chip non-invasive measurement blood glucose conservation of energy method
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Concept Design of a New Deep Draft Platform
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作者 李彬彬 欧进萍 《Journal of Marine Science and Application》 2010年第3期241-249,共9页
The authors analyzed requirements for a new deepwater platform, from conceptual design to hydrodynamic analysis.The design incorporated Deep Draft Multi-Spar (DDMS) that allowed easy fabrication, reduced costs, and pr... The authors analyzed requirements for a new deepwater platform, from conceptual design to hydrodynamic analysis.The design incorporated Deep Draft Multi-Spar (DDMS) that allowed easy fabrication, reduced costs, and provided favorable motion performance.It also provided a dry tree system and other benefits.The conceptual design process included dimension estimation, general arrangements, weight estimation, weight distribution, stability analysis, etc.A high order boundary element method based on potential theory and the modified Morison equation was used to predict the hydrodynamic and viscous effects of this new concept platform.The response amplitude operators (RAOs) were acquired and compared with those of a typical Truss Spar.The response of the platform to the JONSWAP spectra of 3 different extreme ocean conditions was analyzed to evaluate the seakeeping ability of the new concept.The results revealed favorable motion performance due to all the degrees of freedom available. 展开更多
关键词 Spar potential theory Morison equation deepwater platform mooring line heave plate
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Host Engineering for Red Electrophosphorescent Devices
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作者 Li Huiying Luo Yang +1 位作者 Chen.Ping Duan YU 《China Communications》 SCIE CSCD 2012年第2期66-71,共6页
In this paper, we demonstrate that controlled dopantoncentration is an essential issue for charge carriers transporting in red Phosphorescent Organic Light-Emitting Device (PHOLED). Carriers transport via dopant mol... In this paper, we demonstrate that controlled dopantoncentration is an essential issue for charge carriers transporting in red Phosphorescent Organic Light-Emitting Device (PHOLED). Carriers transport via dopant molecules in the emitting layer with a single host, however, via both dopant and host molecules when their energy levels are well aligned. Conditions for reduced driving-voltage and enhanced efficiency of red PHOLED are obtained by employing a mixed host structure. A pure red PHOLED with color coordinates of (0.67, 0.33) has been realized by using only 4 wt% dopant, The device achieves 100 cd/cm2 at 2.9 V, with correspond- ing power efficiency of 9.3im/W and external quantum efficiency of 14.3%. 展开更多
关键词 carriers-transporting red phosphores-cent host-dopant
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Terrestrial water variations in the North China Plain revealed by the GRACE mission 被引量:16
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作者 SU XiaoLi PING JinSong YE QiXin 《Science China Earth Sciences》 SCIE EI CAS 2011年第12期1965-1970,共6页
Using eight years of time-variant gravity measurements from the GRACE gravity satellite mission, we estimate monthly terrestrial water storage variations in the North China Plain between August 2002 and August 2010. W... Using eight years of time-variant gravity measurements from the GRACE gravity satellite mission, we estimate monthly terrestrial water storage variations in the North China Plain between August 2002 and August 2010. We find that during this period, the water storage is not constant but accelerate at a rate of -1.1 cm/yr over time. The study confirms that the relatively long-term trend of water storage in the North China Plain (by 13-point moving average) is consistent well with that by linear fitting. Two hydrological models, CPC and GLDAS, are adopted in calculating surface water variations, with results indicating that they agree with those of GRACE. Furthermore, rates of -0.6 cm/yr for surface water variations and -0.5 cm/yr for groundwater variations are found in the North China Plain during the study period. Decrease of rainfall and the groundwater over-exploitation are possibly the main causes for groundwater depletion in the North China Plain. The results will be helpful for better understanding climatic changes and provide reference for the management of water resources and the establishment of policies on preventing and alleviating natural hazards. 展开更多
关键词 GRACE gravity measurements GROUNDWATER the North China Plain
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Horizontal crustal movement in China fitted by adaptive collocation with embedded Euler vector 被引量:10
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作者 YANG YuanXi ZENG AnMin WU FuMei 《Science China Earth Sciences》 SCIE EI CAS 2011年第12期1822-1829,共8页
The crustal movements of the Chinese mainland include an average regional movement trend of the mainland and complex local deformations. Thus, both trends in the crustal movement of the mainland and local distortions ... The crustal movements of the Chinese mainland include an average regional movement trend of the mainland and complex local deformations. Thus, both trends in the crustal movement of the mainland and local distortions should be simultaneously taken into consideration in crustal movement estimations. A combined collocation model based on Euler vector (taken as trend parameters) and local distortions (taken as signals) is proposed in this paper. We assume that prior covariance matrices between signals and observations should be consistent with their uncertainties. Otherwise, the station movement estimates provided by the collocation will be distorted. Thus, an adaptive collocation estimator based on simplified Helmert variance components is applied. This means that the contributions of signals and observations to estimates of crustal movements are balanced and reasonable, and consistent covariance matrices of the signals and observations are achieved through the adjustment of the adaptive factor. The calculation of actual horizontal movements of the Chinese crust shows that the estimates of horizontal crustal movement velocities are made more accurate by the adaptive collocation model. 展开更多
关键词 adaptive collocation variance component estimation velocity field crustal deformation Euler vector
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Energy evolution in complex impacts with friction 被引量:1
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作者 ZHANG HongJian LIU CaiShan +1 位作者 ZHAO Zhen BROGLIATO Bernard 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第5期875-881,共7页
In this paper, we base a theory established in an impulse-energy level to solve a problem of a disk-bail system, in which a moving ball collides perpendicularly against an disk staying on a horizontal surface. The imp... In this paper, we base a theory established in an impulse-energy level to solve a problem of a disk-bail system, in which a moving ball collides perpendicularly against an disk staying on a horizontal surface. The impact process is an ensemble con- sisting of a point impact coupled with a line contact between bodies of the disk, the ball and the fixed horizontal surface. We experimentally and theoretically show that the post-impact states of the disk dramatically vary with the impacting position of the ball. Explanations are given by investigating the evolutions of the potential energies resided in the points involved in the complex frictional impacts. Good agreements between numerical and experimental results strongly suggest that the evolution of energy together with the dissipation must be reflected in mathematical models if a precise description for the post-impact state of systems is expected. 展开更多
关键词 complex impact FRICTION non-smooth mechanics disk-ball system experiments
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A Physicoempirical Model for Soil Water Simulation in Crop Root Zone
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作者 SHANG Song-Hao MAO Xiao-Min 《Pedosphere》 SCIE CAS CSCD 2011年第4期512-521,共10页
To predict soil water variation in the crop root zone, a general exponential recession (GER) model was developed to depict the recession process of soil water storage. Incorporating the GER model into the mass balan... To predict soil water variation in the crop root zone, a general exponential recession (GER) model was developed to depict the recession process of soil water storage. Incorporating the GER model into the mass balance model for soil water, a GER-based physicoempirical (PE-GER) model was proposed for simulating soil water variation in the crop root zone. The PE-GER model was calibrated and validated with experimental data of winter wheat in North China. Simulation results agreed well with the field experiment results, as well as were consistent with the simulation results from a more thoroughly developed soil water balance model which required more detailed parameters and inputs. Compared with a previously developed simple exponential recession (SER) based physicoempirical (PF^SER) model, PE-GER was more suitable f0r application in a broad range of soil texture, from light soil to heavy soil. Practical application of PE-GER showed that PE-GER could provide a convenient way to simulate and predict the variation of soil water storage in the crop root zone, especially in case of insufficient data for conceptual or hydrodynamic models. 展开更多
关键词 general exponential recession model irrigation scheduling recession process soil texture
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