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数字化管理在抚顺石油一厂动力计量中的应用 被引量:2
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作者 逄立新 《石油化工自动化》 CAS 2001年第4期39-40,47,共3页
在传统的炼油厂动力计量管理中 ,存在一定的被动局面 ,其关键原因是长期以来的器具管理带来的数据处理、信息反馈及其对生产的指导性滞后于现场管理。
关键词 炼油 数字化管理 动力计量 器具管理 “不明去向”量
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非递归式决策树在动力计量计费系统中的应用
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作者 戴龙平 戴莉萍 刘丽珍 《现代电子技术》 2014年第8期91-94,98,共5页
决策树算法的实现往往采用面向对象语言工具来实现,与数据库中的结构通常存在一定的差异,需要进行大量的数据转换。现在充分利用数据库中表结构特点和存储过程中PL/SQL语法的强大性及灵活性,采用一个动力计量计费系统中的数据,快速、有... 决策树算法的实现往往采用面向对象语言工具来实现,与数据库中的结构通常存在一定的差异,需要进行大量的数据转换。现在充分利用数据库中表结构特点和存储过程中PL/SQL语法的强大性及灵活性,采用一个动力计量计费系统中的数据,快速、有效且非递归地实现了决策树C4.5算法中的节点生成、扩展与剪枝主要过程;并进行了规则抽取。应用结果表明,该算法的实现方法具有一定的高效性、稳定性和普适性。 展开更多
关键词 C4 5算法 信息增益 存储过程 动力计量计费系统
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数字化技术在动力计量与节能中的应用
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作者 逄立新 《石油和化工节能》 2005年第2期38-40,共3页
在传统的炼油厂动力计量与节能管理中,存在一定的被动局面,其关键原因是长期以来的器具管理带来的数据处理、信息反馈及其对生产的指导性滞后于现场管理。文章就数字化管理在石油一厂的应用情况做一归纳和总结。
关键词 数字化技术 动力计量系统 节能技术 无线监测网络 频率 炼油行业
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速差动力学分光光度法同时测定苯酚和邻苯二酚
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作者 罗三华 《中国化工贸易》 2013年第12期292-292,共1页
本文根据3-甲基-2-苯并噻唑腙(MUTH)与酚发生偶合反应生产稳定有色配合物的特点,选取以MBTH为显色剂的显色体系,对废水中多组分酚的复合可见光谱运用化学计量学法进行解析。该反应速率适中,苯酚和邻苯二酚的线性范围为0.30—3.0g... 本文根据3-甲基-2-苯并噻唑腙(MUTH)与酚发生偶合反应生产稳定有色配合物的特点,选取以MBTH为显色剂的显色体系,对废水中多组分酚的复合可见光谱运用化学计量学法进行解析。该反应速率适中,苯酚和邻苯二酚的线性范围为0.30—3.0g/mL、0.2—1.8g/mL。 展开更多
关键词 苯酚邻 苯二酚MBTH速差动力学化学计量
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Verification and Improvement of the Ability of CFSv2 to Predict the Antarctic Oscillation in Boreal Spring 被引量:7
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作者 Dapeng ZHANG Yanyan HUANG +2 位作者 Bo SUN Fei LI Huijun WANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2019年第3期292-302,340,共12页
The boreal spring Antarctic Oscillation(AAO)has a significant impact on the spring and summer climate in China.This study evaluates the capability of the NCEP's Climate Forecast System,version 2(CFSv2),in predicti... The boreal spring Antarctic Oscillation(AAO)has a significant impact on the spring and summer climate in China.This study evaluates the capability of the NCEP's Climate Forecast System,version 2(CFSv2),in predicting the boreal spring AAO for the period 1983-2015.The results indicate that CFSv2 has poor skill in predicting the spring AAO,failing to predict the zonally symmetric spatial pattern of the AAO,with an insignificant correlation of 0.02 between the predicted and observed AAO Index(AAOI).Considering the interannual increment approach can amplify the prediction signals,we firstly establish a dynamical-statistical model to improve the interannual increment of the AAOI(DY AAOI),with two predictors of CFSv2-forecasted concurrent spring sea surface temperatures and observed preceding autumn sea ice.This dynamical-statistical model demonstrates good capability in predicting DY AAOI,with a significant correlation coeffcient of 0.58 between the observation and prediction during 1983-2015 in the two-year-out cross-validation.Then,we obtain an improved AAOI by adding the improved DY AAOI to the preceding observed AAOI.The improved AAOI shows a significant correlation coeffcient of 0.45 with the observed AAOI during 1983-2015.Moreover,the unrealistic atmospheric response to March-April-May sea ice in CFSv2 may be the possible cause for the failure of CFSv2 to predict the AAO.This study gives new clues regarding AAO prediction and short-term climate prediction. 展开更多
关键词 Antarctic Oscillation interannual-increment approach CFSv2 dynamical–statistical model prediction
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Study on hydrodynamic vibration in fluidic flowmeter 被引量:2
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作者 WANG Chi-yu ZOU Jun +1 位作者 FU Xin YANG Hua-yong 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第9期1422-1428,共7页
The characteristics of the fluidic flowmeter,which is a combination of impinged concave wall and bistable fluid amplifier,is investigated by experimental studies and numerical simulations. The numerical approaches are... The characteristics of the fluidic flowmeter,which is a combination of impinged concave wall and bistable fluid amplifier,is investigated by experimental studies and numerical simulations. The numerical approaches are utilized to examine the time dependent flow field and pressure field inside the proposed flowmeter. The effect of varying structural parameters on flow characteristics of the proposed fluidic flowmeter is investigated by computational simulations for the optimization. Both the simulation and experimental results disclose that the hydrodynamic vibration,with the same intensity,frequency and 180° phase shift,occurs at axisymmetric points in the feedback channel of the fluidic flowmeter. Using the structural combination of impinged concave wall and bistable fluid amplifier and differential signal processing technique,a novel fluidic flowmeter with excellent immunity and improved sensibility is developed. 展开更多
关键词 FLOWMETER Fluidic Hydrodynamic vibration Coanda effect
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A new approach to quantifying vehicle induced turbulence for complex traffic scenarios 被引量:3
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作者 Yesul Kim Li Huang +1 位作者 Sunling Gong Charles Q.Jia 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第1期71-78,共8页
Traffic-related pollutants adversely affect air quality, especially in regions near major roadways. The vehicleinduced turbulence(VIT) is a significant factor that controls the initial dilution, dispersion, and ultima... Traffic-related pollutants adversely affect air quality, especially in regions near major roadways. The vehicleinduced turbulence(VIT) is a significant factor that controls the initial dilution, dispersion, and ultimately the chemical and physical fate of pollutants by altering the conditions in the microenvironment. This study used a computational fluid dynamics(CFD) software FLUENT to model the vehicle-induced turbulence(VIT) generated on roadways, with a focus on impact of vehicle-vehicle interactions, traffic density and vehicle composition on turbulent kinetic energy(TKE). We show, for the first time, that the overall TKE from multiple vehicles traveling in series can be estimated by superimposing the TKE of each vehicle, without considering the distance between them while the distance is greater than one vehicle length. This finding is particularly significant since it enables a new approach to VIT simulations where the overall TKE is calculated as a function of number of vehicles. We found that the interactions between vehicles traveling next to each other in adjacent lanes are insignificant,regardless the directions of the traffic flow. Consequently, simulations of different traffic scenarios can be substantially simplified by treating two-way traffic as one-way traffic, with less than 5% difference in the overall volume-averaged TKE. We also developed equations that allow the estimation of the overall volume-averaged TKE as a function of the number and the type of vehicles. 展开更多
关键词 Computational fluid dynamics Turbulent kinetic energy Vehicle-induced turbulence Road-induced turbulence Mixed traffic
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Non-locality of Entangled Coherent States and Its Evolution in a Thermal Reservoir
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作者 GONGRen-Shan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第3期413-416,共4页
Regarding the necessary and sufficient condition violating Bell-CHSH's inequality as criterion for nonlocality of entangled states, we present a perturbative calculation determining non-locality of evolving entang... Regarding the necessary and sufficient condition violating Bell-CHSH's inequality as criterion for nonlocality of entangled states, we present a perturbative calculation determining non-locality of evolving entangled states.Furthermore, by means of the perturbative calculation, the non-locality and its evolution of two kinds of entangled coherent states in a thermal reservoir are discussed. 展开更多
关键词 Bell inequality entangled coherent states perturbative calculation
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Absorptive Capacity and Knowledge Flows for Large International Finns: A Survey
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作者 Luigi Aldieri 《Chinese Business Review》 2011年第1期51-66,共16页
The main objective of this paper is that of surveying both theoretic and econometric models exploring the existence of knowledge spillovers and quantifying firm's ability to identify, assimilate, and exploit existing... The main objective of this paper is that of surveying both theoretic and econometric models exploring the existence of knowledge spillovers and quantifying firm's ability to identify, assimilate, and exploit existing information (absorptive capacity). In so doing, we explore different methodologies through which we may analyze the knowledge transmission: both the production function approach and the knowledge function approach. In order to construct the spillover stocks, different dimensions are considered: geographic and technological. 展开更多
关键词 R&D investments technological innovation knowledge diffusion absorptive capacity knowledgespillovers
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Theoretical Investigation on Internal Leakage and Its Effect on the Efficiency of Fluid Switcher-Energy Recovery Device for Reverse Osmosis Desalting Plant 被引量:2
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作者 乞炳蔚 王越 +3 位作者 王照成 张燕平 徐世昌 王世昌 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第11期1216-1223,共8页
This work is focused on the theoretical investigation of internal leakage of a newly developed pi lotscale fluid switcherenergy recovery device (FSERD) for reverse osmosis (RO) system. For the purpose of in creasi... This work is focused on the theoretical investigation of internal leakage of a newly developed pi lotscale fluid switcherenergy recovery device (FSERD) for reverse osmosis (RO) system. For the purpose of in creasing FSERD efficiency and reducing the operating cost of RO, it is required to control the internal leakage in a low level. In this work, the internal leakage rates at different leakage gaps and retentate brine pressures are investigated by computational fluid dynamics (CFD) method and validating experiments. It is found that the internal leak age has a linear relationship with the retentate brine pressure and a polynomial relationship with the scale of leakage gap. The results of the present work imply that low internal leakage and high retentate brine pressure bring benefits to achieve high FSRD efficiency. 展开更多
关键词 internal leakage rate fluid switcher-energy recovery device computational fluid dynamics energytransfer efficiency
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Balance Mechanism Design of Single Cylinder Engine Based on Continuous Mass Distribution of Connecting Rod 被引量:3
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作者 杨陈 郝志勇 郑光泰 《Transactions of Tianjin University》 EI CAS 2009年第4期255-259,共5页
For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and... For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism. In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces to improve the engine’s noise vibration and harshness performance. 展开更多
关键词 multibody dynamics reciprocating inertial force rotating inertial force primary balance shaft
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Fluent-based numerical simulation of flow centrifugal fan 被引量:2
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作者 LI Xian-zhang 《Journal of Coal Science & Engineering(China)》 2011年第2期198-200,共3页
Testing centrifugal fan flow field by physical laboratory is difficult because the testing system is complex and the workload is heavy, and the results observed by naked-eye deviates far from the actual value. To addr... Testing centrifugal fan flow field by physical laboratory is difficult because the testing system is complex and the workload is heavy, and the results observed by naked-eye deviates far from the actual value. To address this problem, the computational fluid dynamics software FLUENT was applied to establish three-dimensional model of the centrifugal fan. The numeral model was verified by comparing simulation data to experimental data. The pressure centrifugal fan and the speed changes in distribution in centrifugal fan was simulated by computational fluid dynamics soft-ware FLUENT. The simulation results show that the gas flow velocity in the impeller increases with impeller radius increase. Static pressure gradually increases when gas from the fan access is imported through fan impeller leaving fans. 展开更多
关键词 centrifugal fan numerical simulation flow field FLUENT software
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Comparison of SCS-CN Determination Methodologies in a Heterogeneous Catchment
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作者 Andrzej WALEGA Boguslaw MICHALEC +1 位作者 Agnieszka CUPAK Magdalena GRZEBINOGA 《Journal of Mountain Science》 SCIE CSCD 2015年第5期1084-1094,共11页
The aim of this study was to assess the runoff amount from a catchment characterized by diverse land uses by using the Soil Conservation Service Curve Number(SCS-CN) method based on Curve Number(CN) defined for domina... The aim of this study was to assess the runoff amount from a catchment characterized by diverse land uses by using the Soil Conservation Service Curve Number(SCS-CN) method based on Curve Number(CN) defined for dominant homogeneous elementary sub-regions.The calculations employed the SCS-CN method,involving the division of the catchment in two homogeneous parts and determining the runoff amount.The obtained results were compared with the results provided by three other CN determination methods,i.e.the Hawkins function,the kinetics equation,and a complementary error function peak.The catchment is located in a mountain dominated by forest land cover.Empirical CN-Precipitation(CN_(emp)-P) data pairs were analyzed using the mentioned methods,and the highest quality score was achieved from model 1.The results suggest that dividing a catchment into two homogeneous areas and determining their separate CN parameters,used later on to calculate the runoff by means of the presented approach,could be an alternative to the standard methods.The described method is relatively easy,and as it does not require an adoption of numerous parameters,and it can be employed for designing hydraulic facilities. 展开更多
关键词 Asymptotic functions Curve Numberparameter Homogenous sub catchment Land cover Lumped model
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The Influence of Blocking Mass Parameters on the Vibration Isolation Performance of a Power Cabin 被引量:1
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作者 计方 姚熊亮 叶曦 《Journal of Marine Science and Application》 2011年第1期25-32,共8页
Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-... Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-band vibration and sound radiation reduction effect of vibration isolation masses located in a base structure was researched.The influence of the blocking mass’ cross-section size and shape parameters and the layout location of the base isolation performance was discussed.Furthermore,the effectiveness of rigid vibration isolation design of the base structure was validated.The results show that the medium and high frequency vibration and sound radiation of a power cabin are effectively reduced by a blocking mass.Concerning weight increment and section requirement,suitably increasing the blocking mass size and section height and reducing section width can result in an efficiency-cost ratio. 展开更多
关键词 rigid isolation blocking mass parameters power cabin vibration isolation performance efficiency-cost ratio
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Experimental research on influence of emulsifier on crystallization quantity of emulsion explosives under dynamic pressure
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作者 HUANG Wen-yao YAN Shi-long WU Hong-bo YUAN Sheng-fang 《Journal of Coal Science & Engineering(China)》 2011年第1期100-103,共4页
Dynamic pressure was applied on emulsion explosive by using an underwater explosion measuring apparatus, and the crystallization quantity was measured by dissolution method after emulsion explosive was pressed; the in... Dynamic pressure was applied on emulsion explosive by using an underwater explosion measuring apparatus, and the crystallization quantity was measured by dissolution method after emulsion explosive was pressed; the influence of emulsi- fier content and type was analyzed. The experimental results show that emulsifier content and type have an important effect on crystallization quantity of emulsion explosive. The crystallization quantity will reduce with Span-g0 content from 2% to 4%, so the demulsification and crystallization will decrease if the emulsifier content improves appropriately and the dynamic pressure resistance will increase. For emulsion explosive emulsified by T-152 and Span-g0, the crystallization quantity with T-152 is less than that of Span-g0 under the same dynamic pressure. This shows that the emulsifying effect ofT-152 is better than Soan-80. 展开更多
关键词 emulsion explosives CRYSTALLIZATION EMULSIFIER dynamic pressure applied chemistry
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Small Scale Refrigerators and Freezers: Thermal Improvements in the Envelope
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作者 Clito Afonso Joaquim Gabriel 《Journal of Environmental Science and Engineering(A)》 2017年第1期1-14,共14页
Like in other sectors of activity, the sustainability in refrigeration systems is a mandatory goal to achieve, namely at house holdings, bars and restaurants, where small-scale refrigerators and freezers are widely us... Like in other sectors of activity, the sustainability in refrigeration systems is a mandatory goal to achieve, namely at house holdings, bars and restaurants, where small-scale refrigerators and freezers are widely used. The aim of this work is to demonstrate experimentally, trough measurements carried out in these equipments, the improvement that can be achieved if several modifications are implemented in traditional household refrigeration systems. In addition, it was also simulated and analysed experimentally a slightly different equipment, a refrigeration system used for draught beverages. Both systems work on a single vapour compression refrigeration with R-134a as working fluid. In the end, by implemented the modifications tested in the virtual model, it was possible to improve their thermal behaviour, a decrease in electrical energy consumption, as well as, the associated CO2 emissions reduction can be attained. In this project, the CFD (Computational Fluid Dynamics) soffware--ANSYS Fluent was used to simulate the ambient temperature and velocity fields inside the refrigerator and in that way to validate the measured results. 展开更多
关键词 Small scalerefrigerators/freezer thermal efficiency air infiltration SUSTAINABILITY CO2 emissions reduction.
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Study on the Determination of Trace Ni(II) by the Catalytic Kinetic Spectrophotometric Method
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作者 JI Hongwei CAO Hengxia XIN Huizhen LI Shuang 《Journal of Ocean University of China》 SCIE CAS 2010年第1期25-30,共6页
A new kinetic spectrophotometric method has been developed for the determination of trace Ni (Ⅱ in natural water. The method is based on the catalytic effect of Ni (Ⅱ) on the oxidation of weak acid brilliant blue... A new kinetic spectrophotometric method has been developed for the determination of trace Ni (Ⅱ in natural water. The method is based on the catalytic effect of Ni (Ⅱ) on the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 in acid medium. The concentration of nickel (Ⅱ) can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The influencing factors are investigated by the orthogonal experimental design. The obtained optimum analytical conditions are: pH = 2.00, CRAWL = 5.00×10^-5 mol·L^-1, c KlO4 = 2.00× 10^-5 mol·L^-1, the reaction time t= 10min and the temperature T = 25 ℃. Under the optimum conditions, the developed method allows the measurement of Ni (Ⅱ) in a range of 0 - 40.0ngmL1. The standard deviation of eleven independent measurements of blank reaction is S = 3.08× 10^-3 and the limit of detection is 2.20ng·mL^-1. The relative standard deviations (RSDs) in six replicate determinations of 5 ngmL-1 and 8 ngmL1 Ni (Ⅱ) are 2.87% and 1.11%, respectively. Moreover, the experiments show few cations and anions can interfere with the measurement of Ni (Ⅱ). The recovery efficiencies of this method are in a range of 97.0%-102.5% in freshwater samples. But there is a decreasing effect, which is about 0.2 times the added Ni (Ⅱ) in seawater medium. After reasonable calibration this processing method is used for the determination of Ni (Ⅱ) in seawater samples successfully. The results show this developed method has high accuracy and precision, high sensitivity, large range of linearity and high speed. The method can, therefore, be employed at room temperature. 展开更多
关键词 Ni(Ⅱ) kinetic-spectrophotometry catalytic effect weak acid brilliant blue dye (RAWL) potassium periodate decreasing effect
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Experimental Study on Jet Blast at Laboratory Scale
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作者 Masato Taguchi Naoki Semba +2 位作者 Koichi Mori Yoshiaki Nakamura Keiichi Ishiko 《Journal of Energy and Power Engineering》 2014年第8期1386-1392,共7页
The flow field of 3D (three-dimensional) wall-jet is investigated. Jet-blast from airplane is simulated by wall-jet setup using a sonic nozzle at a laboratory scale. Farfield velocity and fluctuation distributions a... The flow field of 3D (three-dimensional) wall-jet is investigated. Jet-blast from airplane is simulated by wall-jet setup using a sonic nozzle at a laboratory scale. Farfield velocity and fluctuation distributions are measured by using X-type hot wire anemometer at four measurement planes. As a result, the flow properties of streamwise component are consistent with data which are obtained in previous researches. The secondary flow is also measured on each measurement plane. Reynolds stresses, v'v' and w' w', are analyzed from the fluctuation of the secondary flow. The law of similarity is observed in the dimensionless distributions of mean velocity and fluctuation. However, the distributions in nearer field (i.e., in the measurement plane at X/D = 100) tend to disobey the similarity law, especially in the cases of fluctuation. It seems that jet-blast is not fully developed by reaching X/D = 100. The experimental results are compared with computational results which are obtained by CFD (computational fluid dynamics) with SST (shear-stress transport) turbulence model. And it is shown that the results by the simulation with SST turbulence model do not follow the similarity law. The present database of the Reynolds stresses is critically important for development of a new turbulence model of RANS (reynolds-averaged navier-atokes) simulations on wall-jet. 展开更多
关键词 Experimental fluid dynamics CFD 3D wall jet Reynolds stress secondary flow
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中国省际劳动力流动的主要影响因素分析 被引量:10
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作者 佟新华 孙丽环 《吉林大学社会科学学报》 CSSCI 北大核心 2014年第5期65-72,173,共8页
劳动力是基本的生产要素,其流动性对区域经济发展具有非常重要的作用。目前,中国尚处于市场经济初级阶段,缺乏一体化的资本、技术等要素市场,而劳动力流动性的提高恰恰有助于打破地区间的贸易壁垒,推动区域经济协调发展。因此,政府应该... 劳动力是基本的生产要素,其流动性对区域经济发展具有非常重要的作用。目前,中国尚处于市场经济初级阶段,缺乏一体化的资本、技术等要素市场,而劳动力流动性的提高恰恰有助于打破地区间的贸易壁垒,推动区域经济协调发展。因此,政府应该进一步减少劳动力流动的政策障碍,降低劳动力流动成本,从而提高劳动力流动的资源配置效率,这将对中国经济以及地区间的协调发展具有非常重要的意义。根据多区域劳动力流动决策计量模型,对中国30个省、市、自治区的截面数据进行的检验分析,结果表明:地区间实际收入差异是中国劳动力流动的主要驱动因素,流动限制性政策、流动距离所带来的流动成本对中国劳动力流动模式影响显著,而贸易与劳动力流动存在明显的相互促进作用。 展开更多
关键词 动力流动 迁移成本 多区域劳动力流动决策计量模型
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Multi-spacecraft observations of earthward flow bursts 被引量:8
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作者 MA YuDuan CAO JinBin +3 位作者 REME Henry DANDOURAS Iannis DUNLOP Malcolm LUCEK Elisabeth 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第5期1305-1311,共7页
On the basis of the plasma, electric and magnetic fields jointly observed by Cluster and the Double Star TC-I spacecraft in the Earth's magnetotail, we have investigated the earthward flow bursts by introducing the m... On the basis of the plasma, electric and magnetic fields jointly observed by Cluster and the Double Star TC-I spacecraft in the Earth's magnetotail, we have investigated the earthward flow bursts by introducing the momentum equation in the X-direction in the ideal conditions of magneto hydrodynamics (MHD). One earthward flow burst with a peak in excess of 500 km/s was selected, when the four spacecraft of Cluster were located around -16 RE and TC-1 was located around -10 RE in the X-direction. The inter-spacecraft distances in Y and Z directions were smaller than the statistical spatial scales of the bursty bulk flows. When the Y components of E and -VxB were compared, there was no clear breakdown of the frozen-in condition during the earthward flow burst. With the measured plasma and magnetic parameters from two spacecraft at different positions in the magnetotail, the X component of the pressure gradient was calculated. Magnetic tension was calculated using the mag- netic field measured at four points, which could be compared with the assumed constant in the past research with single satel- lite. When the pressure gradient and the magnetic tension were put into the MHD momentum equation, some samples of the earthward flow bursts were accelerated and some were decelerated. The braking process of the earthward flow burst was more complicated than what the past results had shown. The accelerated samples accounted for about one third of the whole earth- ward flow bursts and discontinuously located among the decelerated elements. The original single earthward flow burst event might be split into several short flow bursts when it was moving to the Earth. Our results may partly illustrate that the duration of fast flows during three phases of substorm becomes short near the Earth. The results are consistent with the past results that fast flows intrude to places earthward the typical braking region. 展开更多
关键词 flow burst pressure gradient magnetic tension BRAKING
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