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63篇 您的检索式:作者名="Xudong Fu"
    题名 作者 年代 出处 被引量
1Simulation of dam breach development for emergency treatment of the Tangjiashan Quake Lake in China显示文摘The Tangjiashan Quake Lake is the largest quake lake triggered by the 5.12 Wenchuan Earthquake that happened on May 12,2008 in China,posing high risk of catastrophic flash flood hazards to downstream human life and properties.A physics-based numerical simulation approach is proposed for real-time prediction of dam breach development of the Tangjiashan Quake Lake in the case of emergency treatment.Bed erosion and lateral development of the dam breach are represented through accounting for the underlying physics including selective sediment transport and gravitational collapse.Conceptualized breach erosion model that involves few parameters enables quick calibration based on the monitored hydrological data in emergency analysis where fully geotechnical information about the barrier dam is not available.The process of dam breach development is found to be nonlinear in cascades due to the combined effects of headcutting and bank collapse.The agreement between the simulation results and the observed data shows the applicability of the present approach for emergency analysis of quake lakes.Limitations will arise in the situation where the soil composition of barrier dam is significantly inhomogeneous.Incorporation of circular arc failure for cohesive soil and lateral seepage in bank slope will also enhance its applicability to complex situations.WANG GuangQian,LIU Fan,FU XuDong & LI TieJian State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China 2008Science China(Technological Sciences)2008,51,S2:25
2Current status of diagnosis and treatment of bladder cancer in China-Analyses of Chinese Bladder Cancer Consortium database显示文摘Objective:To investigate current status of diagnosis and treatment of bladder cancer in China.Methods:A database was generated by Chinese Bladder Cancer Consortium(CBCC).From January 2007 to December 2012,14,260 cases from 44 CBCC centers were included.Data of diagnosis,treatment and pathology were collected.Results:The average age was 63.5 year-old and most patients were male(84.3%).The most common histologic types were urothelial carcinoma(91.4%),adenocarcinoma(1.8%),and squamous carcinoma(1.9%).According to 1973 and 2004 WHO grading system,42.0%,41.0%,and 17.0% of patients were grade 1,2,and 3,and 16.0%,48.7%,and 35.3% of patients were papillary urothelial neoplasms of low malignant potential,low,and high grade,respectively.Non-muscle invasive bladder cancer(NMIBC)and muscle invasive bladder cancer(MIBC)were 25.2% and 74.1%,respectively(0.8% not clear).Carcinoma in situ was only 2.4%.Most patients were diagnosed by white-light cystoscopy with biopsy(74.3%).Fluorescence and narrow band imaging cystoscopy had additional detection rate of 1.0% and 4.0%,respectively.Diagnostic transurethral resection(TUR)provided detection rate of 16.9%.Most NMIBCs were treated with TUR(89.2%).After initial TUR,2.6%accepted second TUR,and 45.7%,69.9%,and 58.7% accepted immediate,induced,and maintenance chemotherapy instillation,respectively.Most MIBCs were treated with radical cystectomy(RC,59.7%).Laparoscopic RCs were 35.1%,while open RC 63.4%.Extended and standard pelvic lymph node dissection were 7% and 66%,respectively.Three most common urinary diversions were orthotopic neobladder(44%),ileal conduit(31%),and ureterocutaneostomy(23%).Only 2.3% of patients accepted neo-adjuvant chemotherapy and only 18%of T3 and T4 patients accepted adjuvant chemotherapy.Conclusion:Disease characteristics are similar to international reports,while differences of diagnosis and treatment exist.This study can provide evidences for revisions of the guideline on bladder cancer in China.Kaiwen Li Tianxin Lin Wei Xue Xin Mu Enci Xu Xu Yang Fubao Chen Guangyong Li Lulin Ma Guoliang Wang Chaozhao Liang Haoqiang Shi Ming Li Mao Tang Xueyi Xue Yisong Lv Yaoliang Deng Chengyang Li Zhiwen Chen Xiaozhou Zhou Fengshuo Jin Xudong Liu Jinxin Wei Lei Shi Xin Gou Weiyang He Liqun Zhou Lin Cai Baiye Jin Guanghou Fu Xiangbo Kong Hongyan Sun Ye Tian Lang Feng Tiejun Pan Yiyi Wu Dongwen Wang Hailong Hao Benkang Shi Yaofeng Zhu Qiang Wei Ping Han Changli Wu Dawei Tian Zhangqun Ye Zheng Liu Zhiping Wang Junqiang Tian Lin Qi Minfeng Chen Wei Li Jinchun Qi Gongxian Wang Longlong Fu Zhaolin Sun Guangheng Luo Zhoujun Shen Zhaowei Zhu Jinchun Xing Zhun Wu Dong Wei Xin Chen Yanqun Na Hongfeng Guo Chunxi Wang Zhihua Lu Chuize Kong Yang Liu Jin Yang Jianyun Hu Xin Gao Jielin Li Changjun Yin Pu Li Shan Chen Zhen Du Jiongming Li Yongji Yan Xu Zhang Shuang Huang Fangjian Zhou Zhiling Zhang Yinghao Sun Shuxiong Zeng Song Cen Jiaquan Zhou Hanzhong Li Jin Wen Jian Huang 2015Asian Journal of Urology2015,2,2:21
3Stereotactic aspiration for hypertensive intracerebral haemorrhage in a Chinese population:a retrospective cohort study显示文摘Objective We aimed to compare the therapeutic effects of stereotactic aspiration and best medical management in patients who developed supratentorial hypertensive intracerebral haemorrhage(HICH)with a volume of haemorrhage between 20 and 40 mL.Methods The clinical data of 220 patients with supratentorial HICH with a volume between 20 and 40 mL were retrospectively analysed.Among them,142 received stereotactic aspiration surgery(stereotactic aspiration group)and 78 received best medical management(conservative group).All were followed up for 6 months.Multivariate logistic regression and Kaplan-Meier survival curves were used to compare the outcome between the two groups.results The rebleeding rate was lower in the group that had stereotactic aspiration when compared with the group with medical treatment(6[4.2%]vs 9[11.5%],χ2=4.364,p=0.037).After 6 months,although the mortality rate did not differ significantly between the two groups(8 cases[5.6%]vs 10 cases[12.8%],χ2=3.461,p=0.063),the rate of a favourable outcome was higher in the group who received stereotactic aspiration(χ2=15.870,p=0.000).Logistic regression identified that medical treatment(OR=1.64,p=0.000)was an independent risk factor for an unfavourable outcome.The Kaplan-Meier curves indicated that the median favourable outcome time in the stereotactic aspiration group was 59.5 days compared with that in the medically treated group(87.0 days).The log-rank test indicated that the prognosis at 6 months was better for those treated with stereotactic haematoma aspiration(χ2=29.866,p=0.000).However,the 6-month survival rate was similar between the two groups(χ2=3.253,p=0.068).Conclusions Stereotactic haematoma aspiration significantly improved the quality of life,although did not effectively reduce the rate of mortality.When selected appropriately,patients with HICH may benefit from this type of surgical intervention.Xuyang Zhang Shaolong Zhou Qiang Zhang Xudong Fu Yuehui Wu Jiasheng Liu Bo Liang Zhuo Yang Xinjun Wang 2019Stroke & Vascular Neurology2019,4,1:19
4Optimal design of anchor cables for slope reinforcement based on stress and displacement fields显示文摘How to determine reasonable position and length of anchor cable is a frequently encountered but not well addressed problem in slope reinforcement projects. In this paper, the variable-modulus elastoplastic strength reduction method(SRM) is used to obtain the stress field, displacement field, and factor of safety of slope. Slope reinforcement using anchor cables is modeled by surface loading, i.e. different distributions of surface loading represent various reinforcement schemes. Optimal reinforcement scheme of anchor cables can be determined based on slope stress and displacement fields. By comparing the factor of safety and stress field before and after slope reinforcement, it is found that better reinforcement results can be achieved if strong reinforcement is applied upon the regions with high stress and large displacement. This method can well optimize the arrangement of anchor cables. In addition,several cases are employed to verify the proposed method.Guanghua Yang Zhihui Zhong Yucheng Zhang Xudong Fu 2015Journal of Rock Mechanics and Geotechnical Engineering2015,7,4:12
5Turbulent burst around experimental spur dike显示文摘三维的狂暴的流动地被使用微声学的 Doppler 速度计在一个试验性的刺激堤附近测量。包括外面的相互作用的狂暴的爆炸事件的时间部分,喷射,里面的相互作用,并且扫在形成前后在堤的邻居在每个象限被分析搜索洞。床附近的超过 80% 爆炸事件有为扁平、搜索的床表面的大小降低顺序。喷射并且扫在本地人前是流行的搜索被开始,然后在 scour 洞被形成以后,外面的相互作用是主导的。有条件的雷纳兹压力和狂暴的速度的高顺序的时刻沿着 thalweg 被分析。uw 对的大小比在 scour 地区的 vw 对的那些大得多。在四个爆炸事件之中,喷射并且扫是贡献雷纳兹压力的更高的顺序事件。因为沉积乘火车和运输仔细在床附近与狂暴的爆炸被联系,发展极大地搜索洞在床附近取决于更高的顺序事件。Jennifer DUAN Li HE Guangqian WANG Xudong FU 2011International Journal of Sediment Research2011,26,4:7
6Sediment delivery ratio and its uncertainties on flood event scale:Quantification for the Lower Yellow River显示文摘Sediment delivery ratio(SDR)for fluvial rivers was formulated with sediment rating curve.The observed data of SDR on flood event scale of the Lower Yellow River(LYR)were adopted to examine the formulation and to calibrate the model parameters.A regression formula of SDR was then established and its 95%prediction interval was accordingly quantified to represent its overall uncertainties.Three types of factors including diversity of the incoming flow conditions,river self-regulation processes,and human activities were ascribed to the uncertainties.The following were shown:(1)With the incoming sediment coefficient(ISC)being a variable,it was not necessary to adopt the incoming flow discharge as the second variable in the formulation of SDR;and(2)ISC=0.003 and therefore SDR=2 might be a threshold for distinguishing the characteristics of sediment transport within the LYR.These findings would highlight sediment transport characteristics on the scale of flood event and contribute to uncertainty based analysis of water volume required for sediment transport and channel maintenance of the LYR.FU XuDong 1,JIANG LiWei 1,WU BaoSheng 1,HU ChunHong 2,WANG GuangQian 1 &FEI XiangJun 1 1State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China 2China Institute of Hydropower and Water Resources Research,Beijing 100044,China 2010Science China(Technological Sciences)2010,53,3:7
7An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow显示文摘The stall mechanism of the NASA Rotor 37 is investigated through the analysis of the critical flow structures near the stall under the transonic condition. The performance of the rotor with Circumferential Grooves Casing Treatment (CGCT) is also studied based on the Reynolds-Averaging Navier-Stokes approach. The study finds that stall margin improvement can be achieved without significant penalty on the efficiency for the two CGCT configurations applied. The effects of circumferential grooves on the critical flow structures are studied through the analysis of the tip leakage mass and momentum transport that further re-veal the CGCT mechanism.HUANG XuDong,CHEN HaiXin,SHI Ke & FU Song School of Aerospace,Tsinghua University,Beijing 100084,China 2010Science China(Physics,Mechanics & Astronomy)2010,53,2:7
8A large time step Godunov scheme for free-surface shallow water equations显示文摘An algorithm for simulating free surface flows is presented using large time step based on the wave-propagation method proposed by LeVeque,and an exact Riemann solver is used.A multiple wave approximation approach was suggested for eliminating the discontinuities found in the rarefaction fans of dam-breaking flows.In addition,we use the random choice method to reduce non-physical oscillations.Applications demonstrate that the algorithm proposed in this paper can considerably increase the CFL number up to 25when modeling dam-break flows,while retaining satisfactory accuracy and efficiency.This suggests that our algorithm has the potential to be applied to modeling free surface flows.Renyi Xu Deyu Zhong Baosheng Wu Xudong Fu Runze Miao 2014Chinese Science Bulletin2014,59,21:5
9Planar Velocity Distribution of Viscous Debris Flow at Jiangjia Ravine,Yunnan,China:A Field Measurement Using Two Radar Velocimeters显示文摘Characteristics of planar velocity distribution of vis-cous debris flow were analyzed using the measured data at Jiangjia Ravine,Yunnan,China. The velocity data were measured through using two radar velocimeters. The cross-sectional mean velocities were calculated and used to examine Kang et al's(2004) relation-ship,which was established for converting the flow velocity at river centerline measured by a radar velocimeter into the mean velocity based on the stop-watch method. The velocity coefficient,K,defined by the ratio of the mean velocity to the maximum ve-locity,ranges from 0.2 to 0.6. Kang et al's(2004) relationship was found being inapplicable to flows with K smaller than 0.43. This paper contributes to show the complexity of the planar velocity distribution of viscous debris flows and the applicability of Kang et al's relationship.FU Xudong WANG Guangqian KANG Zhicheng FEI Xiangjun 2007Wuhan University Journal of Natural Sciences2007,12,4:5
10KINETIC MODELING OF CONSTITUTIVE RELATIONS FOR PARTICLE MOTION IN LOW TO MODERATELY CONCENTRATED FLOWS显示文摘Formulating underlying mechanisms of concentrated solid-liquid flows is essential for simulation of various industrial processes and natural phenomena. A generalized constitutive model for particle motion in flows with low to moderate solids concentrations is developed. This generalized model facilitates characterization of inelastic collisions, particle-fluid interactions, and shearing effects. Moderately concentrated simple shear flows of a sand-water mixture are analyzed, and comparisons of model predictions and experimental data are in good agreement. This model exhibits sound performance in characterizing particle motion for wide ranges of concentration and shear rate, and may supply a reasonable and competent alternative to previous models developed for dilute and rapid-granular flows when applied to moderately concentrated situations. The concentration approaches zero (C → 0) asymptote is observed at a relatively high shear rate in model predictions. Assumption of low collisional dissipation of the particle phase as C → 0 is more reasonable for this observation, compared to that without the interstitial fluid effect. Accurately modeling energy dissipation is important for characterizing the stability of dilute simple shear flows of solid-liquid mixtures. Incorporating friction forces will also facilitate improvement of the applicability of this generalized model to flows at extremely high concentrations.Guangqian WANG Xudong FU Xingkui WANG 2005International Journal of Sediment Research2005,20,4:3
11Utilization and quality assessment of digestive endoscopy in China:results from 5-year consecutive nationwide surveys显示文摘Background:Worldwide,the volume and availability of digestive endoscopy have undergone dramatic development in recent years,with increasing attention on quality assurance.We investigated the utilization and quality of digestive endoscopy in China from 2015 to 2019 and developed a quantitative quality evaluation tool for medical institutions.Methods:We invited all tertiary/secondary hospitals in Chinese mainland to participate in the survey annually.The questionnaires included the personnel,annual volume,and quality indicators of endoscopy.An endoscopy quality index(EQI)was developed based on recorded quality indicators using principal component analysis to determine the relative weight.Results:From 2015 to 2019,806,1412,2644,2468,and 2541 hospitals were respectively enrolled in this study.The average annual volume of endoscopy increased from 12,445 to 16,206(1.30-fold)and from 2938 to 4255(1.45-fold)in tertiary and secondary hospitals,respectively.The most obvious growth was observed in diagnostic colonoscopy(1.44-fold for all hospitals after standardization).The proportion of early cancer among all esophageal and gastric cancers during diagnostic esophagogastroduodenoscopy increased from 12.3%(55,210/448,861)to 17.7%(85,429/482,647)and from 11.4%(69,411/608,866)to 16.9%(107,192/634,235),respectively.The adenoma detection rate of diagnostic colonoscopy increased from 14.9%(2,118,123/14,215,592)to 19.3%(3,943,203/20,431,104).The EQI model included 12 quality indicators,incorporating 64.9%(7.792/12)of the total variance into one comprehensive index.According to the EQI measurements,the quality of endoscopy was higher in tertiary hospitals and hospitals in developed areas with higher volume or more endoscopists than that in other hospitals.Conclusions:Digestive endoscopy in China has developed considerably in recent years in terms of both volume and quality.The EQI is a promising tool to quantify the quality of endoscopy at different hospitals.Lei Xin Ye Gao Zhiyuan Cheng Tianjiao Wang Han Lin Yanan Pang Chang Sun Zengjun Fu Zhaoshen Li Xudong Ma Luowei Wang 2022Chinese Medical Journal2022,135,16:3
12A physics-based hydro-geomorphologic simulation utilizing cluster parallel computing显示文摘To conduct a large-scale hydrologic-response and landform evolution simulation at high resolution,a complex physics-based numerical model,the Integrated Hydrology Model(InHM),was revised utilizing cluster parallel computing.The parallelized InHM(ParInHM) divides the simulated area into multiple catchments based on geomorphologic features,and generates boundary-value problems for each catchment to construct simulation tasks,which are then dispatched to different computers to start the simulation.Landform evolution is considered during simulating and implemention in one framework.The dynamical Longest-Processing-Time(LPT) first scheduling algorithm is applied to job management.In addition,a pause-integratedivide-resume routine method is used to ensure the hydrologic validity during the simulation period.The routine repeats until the entire simulation period is finished.ParInHM has been tested in a computer cluster that uses 16 processors for the calculation,to simulate 100 years' hydrologic-response and soil erosion for the 117-km2 Kaho'olawe Island in the Hawaiian Islands under two different mesh resolutions.The efficiency of ParInHM was evaluated by comparing the performance of the cluster system utilizing different numbers of processors,as well as the performance of non-parallelized system without domain decomposition.The results of this study show that it is feasible to conduct a regional-scale hydrologic-response and sediment transport simulation at high resolution without demanding significant computing resources.RAN QiHua SU DanYang FU XuDong WANG GuangQian 2013Science China(Technological Sciences)2013,56,8:3
13Particulate matter pollution in Kunshan High-Tech zone: Source apportionment with trace elements, plume evolution and its monitoring显示文摘Particulate matter(PM) in the Kunshan High-Tech zone is studied during a three-month campaign. PM and trace elements are measured by the online pollution monitoring, forecastwarning and source term retrieval system AS3. Hourly measured concentrations of PM_(10), PM_(2.5) and 16 trace elements in the PM_(2.5) section(Ca, Pb, Cu, Cl, V, Cr, Fe, Ti, Mn, Ni, Zn, Ga, As, Se, Sr, Ba)are focused. Source apportionment of trace elements by Positive Matrix Factorization modeling indicates that there are five major sources, including dust, industrial processing, traffic,combustion, and sea salt with contribution rate of 23.68%, 21.66%, 14.30%, 22.03%, and 6.89%,respectively. Prediction of plume dispersion from concrete plant and traffic emissions shows that PM_(10) pollution of concrete plant is three orders of magnitude more than that of the traffic. The influence range can extend to more than 3 km in 1 hr. Because the footprint of the industrial plumes is constantly moving according to the local meteorological conditions, the fixed monitoring sites scattered in a few hundred meters haven't captured the heaviest pollution plume at the local scale of a few km^2. As a more intensive monitoring network is not operationally possible, the use of online modeling gives accurate and quantitative information of plume location, which increases the spatial pollution monitoring capacity and improves the understanding of measurement data. These results indicate that the development of the AS3 system, which combines monitoring equipment and air pollution modeling systems, is beneficial to the real-time pollution monitoring in the industrial zone.Suwei Zhang Qijie Zhang Armand Albergel Didier Buty Liangmin Yu Haiting Wang Wuxia Bi Peng Cheng Fu Chen Jun Fang Ruirui Hou Xudong Luan Changgan Shu Jingjing Su 2018Journal of Environmental Sciences2018,30,9:3
14Radiation belt electron scattering by whistler-mode chorus in the Jovian magnetosphere: Importance of ambient and wave parameters显示文摘Whistler-mode chorus waves are regarded as an important acceleration mechanism contributing to the formation of relativistic and ultra-relativistic electrons in the Jovian radiation belts. Quantitative determination of the chorus wave driven electron scattering effect in the Jovian magnetosphere requires detailed information of both ambient magnetic field and plasma density and wave spectral property, which however cannot be always readily acquired from observations of existed missions to Jupiter. We therefore perform a comprehensive analysis of the sensitivity of chorus induced electron scattering rates to ambient magnetospheric and wave parameters in the Jovian radiation belts to elaborate to which extent the diffusion coefficients depend on a number of key input parameters. It is found that quasi-linear electron scattering rates by chorus can be strongly affected by the ambient magnetic field intensity, the wave latitudinal coverage, and the peak frequency and bandwidth of the wave spectral distribution in the Jovian magnetosphere, while they only rely slightly on the background plasma density profile and the peak wave normal angle, especially when the wave emissions are confined at lower latitudes. Given the chorus wave amplitude, chorus induced electron scattering rates strongly depend on Jovian L-shell to exhibit a tendency approximately proportional to L_J^3. Our comprehensive analysis explicitly demonstrates the importance of reliable information of both the ambient magnetospheric state and wave distribution property to understanding the dynamic electron evolution in the Jovian radiation belts and therefore has implications for future mission planning to explore the extreme particle radiation environment of Jupiter and its satellites.BinBin Ni Jing Huang YaSong Ge Jun Cui Yong Wei XuDong Gu Song Fu Zheng Xiang ZhengYu Zhao 2018Earth and Planetary Physics2018,2,1:3
15Reduced intensity conditioning and co-transplantation of unrelated peripheral stem cells combined with umbilical cord mesenchymal stem/stroma cells for young patients with refractory severe aplastic anemia显示文摘Yuewen Fu Qian Wang Jian Zhou Shengquan Liu Baijun Fang Xudong Wei Yongping Song 2013International Journal of Hematology2013,,6:2
16Stochastic formulation of particle kinetics in wall-bounded two-phase flows显示文摘This paper presents a generalized framework of stochastic modeling for particle kinetics in wall-bounded flow.We modified a reflected Brownian motion process and straightforwardly obtained a Kramers equation for particle probability density function(PDF).After the wall effects were accounted for as a drift from zero in the mean displacement and suppression in the diffusivity of a particle,an analytical solution was worked out for PDF.Three distinguishable mechanisms were identified to affect the profile of particle probability distribution:external forces,turbophoresis effect,and wall-drift effect.The proposed formulation covers the Huang et al.(2009)model of a wall that produces electrostatic repulsion force and van der Waals force,as well as Monte-Carlo solutions for the Peter and Barenbrug(2002)model under a variety of relaxation times.Moreover,it successfully reproduces the two patterns of particle concentration profiles observed in experiments of sediment-laden open-channel flows.The strength of the wall-drift effect was found to be connected with the interaction frequency between particle and wall.Further exploration of the relationship among flow turbulence,particle inertia,and particle concentration is worthwhile.MA HongBo FU XuDong 2014Science China(Technological Sciences)2014,57,10:2
17An empirical model of the global distribution of plasmaspheric hiss based on Van Allen Probes EMFISIS measurements显示文摘Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves.To reproduce these empirical results,we establish a fitting model that is a thirdorder polynomial function of L-shell,magnetic local time(MLT),magnetic latitude(MLAT),and AE*.Quantitative comparisons indicate that the model’s fitting functions can reflect favorably the major empirical features of the global distribution of hiss wave intensity,including substorm dependence and the MLT asymmetry.Our results therefore provide a useful analytic model that can be readily employed in future simulations of global radiation belt electron dynamics under the impact of plasmaspheric hiss waves in geospace.JingZhi Wang Qi Zhu XuDong Gu Song Fu JianGuang Guo XiaoXin Zhang Juan Yi YingJie Guo BinBin Ni Zheng Xiang 2020Earth and Planetary Physics2020,4,3:2
18PCR-based approaches for identification of multi-copy transgene integration sites in mouse genome显示文摘Generation of transgenic mice by DNA microinjection has become one of the most important technologies in studying gene function in vivo. Ran- dom integration of transgene often results in inser- tional mutation which may complicate phenotype analysis of transgenic mice and/or create a good opportunity to study the function of endogenous gene. However,the utilization of these potentially valuable resources is hampered due to lack of efficient ap- proaches for rapid identification of multi-copy trans- gene integration sites. Here we propose two PCR-based approaches to identifying trans- gene/genome junction sequences. The efficiency of these two strategies was tested in 9 independent transgenic mouse lines. Among them,the transgene in 8 mouse lines was clearly localized to certain chromosome regions. These rapid and efficient ap- proaches will greatly facilitate the study of insertional mutation due to transgene integration.ZHAO Xudong DANG Suying LIANG Bin LEI Xia CHEN Zheng WANG Long YAN Lanzhen SUN Hantang FU Jiliang FEI Jian WANG Zhugang 2006Chinese Science Bulletin2006,51,18:2
19On the loss mechanisms of radiation belt electron dropouts during the 12 September 2014 geomagnetic storm显示文摘Radiation belt electron dropouts indicate electron flux decay to the background level during geomagnetic storms,which is commonly attributed to the effects of wave-induced pitch angle scattering and magnetopause shadowing.To investigate the loss mechanisms of radiation belt electron dropouts triggered by a solar wind dynamic pressure pulse event on 12 September 2014,we comprehensively analyzed the particle and wave measurements from Van Allen Probes.The dropout event was divided into three periods:before the storm,the initial phase of the storm,and the main phase of the storm.The electron pitch angle distributions(PADs)and electron flux dropouts during the initial and main phases of this storm were investigated,and the evolution of the radial profile of electron phase space density(PSD)and the(μ,K)dependence of electron PSD dropouts(whereμ,K,and L^*are the three adiabatic invariants)were analyzed.The energy-independent decay of electrons at L>4.5 was accompanied by butterfly PADs,suggesting that the magnetopause shadowing process may be the major loss mechanism during the initial phase of the storm at L>4.5.The features of electron dropouts and 90°-peaked PADs were observed only for>1 MeV electrons at L<4,indicating that the wave-induced scattering effect may dominate the electron loss processes at the lower L-shell during the main phase of the storm.Evaluations of the(μ,K)dependence of electron PSD drops and calculations of the minimum electron resonant energies of H+-band electromagnetic ion cyclotron(EMIC)waves support the scenario that the observed PSD drop peaks around L^*=3.9 may be caused mainly by the scattering of EMIC waves,whereas the drop peaks around L^*=4.6 may result from a combination of EMIC wave scattering and outward radial diffusion.Xin Ma Zheng Xiang BinBin Ni Song Fu Xing Cao Man Hua DeYu Guo YingJie Guo XuDong Gu ZeYuan Liu Qi Zhu 2020Earth and Planetary Physics2020,4,6:2
20Mechanisms of particle vertical diffusion in sediment-laden flows显示文摘Diffusion coefficient of natural sediments andeffects of lift force and gradient in particle velocity fluctua-tions were investigated through using a closed kinetic model.Comparison against experimental data of Einstein & Chien(1955) validated the model. The diffusion coefficient εyy ofmedium and large sediments distinctly exceeds fluid eddyviscosity V^tf, while εyy of fine sediments approximately equals V^tf. In the measured region of 0.03WANG Guangqian FU Xudong Key Lab for Water and Sediment Sciences of Ministry of Education, Tsinghua University, Beijing 100084, China Correspondence should be addressed to Wang Guanqian 2004Chinese Science Bulletin2004,49,10:2
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