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| 1 | Seismic damage-cracking analysis of arch dams using different earthquake input mechanisms显示文摘In this study, a nonlinear model is presented for analysis of damage-cracking behavior in arch dams during strong earthquakes using different seismic input mechanisms. The nonlinear system includes a plastic-damage model for cyclic loading of concrete considering strain softening and a contact boundary model of contraction joint opening. Two different earthquake input mechanisms are used for comparison, including massless foundation input model and viscous-spring boundary model considering radiation damping due to infinite canyon. The results demonstrate that effects of seismic input mechanism and radiation damping on nonlinear response and damage-cracking of the dam are significant. Compared with the results of using massless foundation input model, the damage-cracking region and contraction joint opening are substantially reduced when using viscous-spring boundary model to take into account radiation damping. However, if the damping ratio of the dam is artificially increased to about 10%―15% for massless foundation input model, the joint opening and damage-cracking of the dam are comparable to the results obtained from the viscous-spring boundary model. | JianWen Pan ChuHan Zhang JinTing Wang YanJie Xu | 2009 | Science China(Technological Sciences)2009，52，2： | 18 |
| 2 | Meteorological mechanism for a large-scale persistent severe ozone pollution event over eastern China in 2017显示文摘An intensive and persistent regional ozone pollution event occurred over eastern China from 25 June to 5 July 2017.73 out of 96 selected cities,most located in the Beijing-TianjinHebei and the surrounding area(BTHS),suffered severe ozone pollution.A north-south contrast ozone distribution,with higher ozone(199±33μg/m3)in the BTHS and lower ozone(118±25μg/m^3)in the Yangtze River Delta(YRD),was found to be dominated by the position of the West Pacific Subtropical High(WPSH)and mid-high latitude wave activities.In the BTHS,the positive anomalies of geopotential height at 500 hPa and temperature at the surface indicated favorable meteorological conditions for local ozone formation.Prevailing northwesterly winds in the mid-high troposphere and warm advection induced by weak southerly winds in the low troposphere resulted in low-moderate relative humidity(RH),less total cloud cover(TGC),strong solar radiation and high temperatures.Moreover,southerly winds prevailing over the BTHS aggravated the pollution due to regional transportation of O3 and its precursors.On one hand,the deep sinking motion and inversion layer suppressed the dispersion of pollutants.On the other hand,O3-rich air in the upper layer was maintained at night due to temperature inversion,which facilitated O3 vertical transport to the surface in the next-day morning due to elevated convection.Generally,temperature,UV radiation,and RH showed good correlations with O3 in the BTHS,with rates of 8.51(μg/m^3)/℃(within the temperature range of 20-38℃),59.54(μg/m^3)/(MJ/m^2)and-1.93(μg/m^3)/%,respectively. | Jia Mao Lili Wang Chuhan Lu Jingda Liu Mingge Li Guiqian Tang Dongsheng Ji Nan Zhang Yuesi Wang | 2020 | Journal of Environmental Sciences2020，32，6： | 18 |
| 3 | A Modified Algorithm for Identifying and Tracking Extratropical Cyclones显示文摘In this study, a modified identification and tracking algorithm for extratropical cyclones is developed. This identification scheme is based on triangular-mesh contouring techniques combined with a connected-component labeling method in order to detect the outer boundaries and spatial domain characteristics of individual cyclones. A new tracking method allowing for the identification of cyclone merging and splitting events, as well as short-lived windstorms, is developed to reduce the uncertainty in the tracking of extratropical cyclones. I also show that this method excludes the tracks of open systems that would have been unnecessarily detected using conventional NCP methods. The climatological features of the distribution of cyclone frequencies are substantially larger over the traditional storm track regions compared to those seen in previous studies. Interestingly, a significant increase in the cyclone density in the Arctic occurs during all four seasons(up to 19%in summer) compared to that seen with a latitude–longitude gridded mesh analysis. I develop two new regional intensity indices(depth and vorticity) based on the cyclonic domain to better quantify the cyclonic activity in the Arctic region, and find that the interannual variabilities in these two indices are highly consistent. The results of this analysis may shed light on high-latitude cyclonic behavior studies via the newly detected 2D cyclone atlas derived from this cyclonic-domain-based algorithm. | Chuhan LU | 2017 | Advances in Atmospheric Sciences2017，34，7： | 10 |
| 4 | Multi-scale Cyclone Activity in the Changjiang River–Huaihe River Valleys during Spring and Its Relationship with Rainfall Anomalies显示文摘Based on the recognition framework of the outermost closed contours of cyclones, an automated identification algorithm capable of identifying the multi-scale cyclones that occur during spring in the Changjiang River–Huaihe River valleys(CHV)were developed. We studied the characteristics of the multi-scale cyclone activity that affects CHV and its relationship with rainfall during spring since 1979. The results indicated that the automated identification algorithm for cyclones proposed in this paper could intuitively identify multi-scale cyclones that affect CHV. The algorithm allows for effectively describing the shape and coverage area of the closed contours around the periphery of cyclones. We found that, compared to the meso- and sub-synoptic scale cyclone activities, the synoptic-scale cyclone activity showed more intimate correlation with the overall activity intensity of multi-scale CHV cyclones during spring. However, the frequency of occurrence of sub-synoptic scale cyclones was the highest, and their effect on changes in CHV cyclone activity could not be ignored. Based on the area of impact and the depth of the cyclones, the sub-synoptic scale, synoptic scale and comprehensive cyclone intensity indices were further defined, which showed a positive correlation with rainfall in CHV during spring. Additionally, the comprehensive cyclone intensity index was a good indicator of strong rainfall events. | Yujing QIN Chuhan LU Liping LI | 2017 | Advances in Atmospheric Sciences2017，34，2： | 10 |
| 5 | On the interannual variation in spring atmospheric inter-hemispheric oscillation linked to synchronous climate in China显示文摘Based on NCEP/NCAR monthly mean reanalysis data and surface observations of Chinese stations, inter-hemispheric oscillations (IHO) of spring atmospheric mass on an interannual basis in conjunction with the linkage to the synchronous climate over China are studied. Results suggest that the spring IHO exhibits a significant seesaw pattern for air mass at bi-hemispheric mid-high latitudes, with a consistent vertical circulation structure. The EOF decomposition of zonally mean surface pressures without signals of Arctic Oscillation (AO) and Antarctic Oscillation (AAO) indicates that the EOF1 IHO feature is remarkable, with the corresponding time coeficients correlated with the spring IHO index (IIHO) at 0.93; the spring IHO bears a close relation to the synchronous climate in China, showing the surface pressure, temperature and relative humidity over the country to be in good correlation with IIHO; the spring duststorms in Qinghai, Gansu, Shaanxi and Inner Mongolia have bearing on IHO. Positive-phase IIHO promotes the strengthening of the Siberian high, during which zonal winds between 60°E and 150°W show a longitudinal teleconnection structure extending from the Arctic to Antarctica, leading to positive westerly wind anomalies over Asia, affecting the spring climate of China. | Chuhan Lu Zhaoyong Guan | 2009 | Progress in Natural Science:Materials International2009，19，9： | 8 |
| 6 | The seasonal cycle of interhemispheric oscillations in mass field of the global atmosphere显示文摘Using the daily and monthly data of surface air pressure, meridional wind, radiation and water vapor from NCEP/NCAR reanalysis for the period of 1979―2006, we have examined the seasonal variations of the interhemispheric oscillations (IHO) in mass field of the global atmosphere. Our results have demonstrated that IHO as observed in surface air pressure field shows the distinct seasonal cycle. This seasonal cycle has an interhemispheric seesaw structure with comparable annual ranges of surface air pressure in the Southern and Northern Hemispheres. Mass of water vapor changes out-of-phase between the Southern and Northern Hemispheres, showing clearly a seasonal cycle with its annual range almost equivalent to annual range of the IHO seasonal cycle. Amazingly, the cross-equatorial flow is found to be induced by annual changes in water vapor mass as a response of the atmosphere to seasonal cycle of forcing from hemispheric net surface short- and long-wave radiations. The IHO seasonality exhibits its larger variations in magnitude in mid-latitudes other than in other regions of the globe. Additionally, our results also show that the global air mass is redistributed seasonally not only between the Northern and Southern Hemispheres but also between land and sea. This land-sea air mass redis- tribution induces a zonal pattern of surface air pressure in the Northern Hemisphere but the meridional pattern in the Southern Hemisphere. | LU ChuHan GUAN ZhaoYong MEI ShiLong QIN YuJing | 2008 | Chinese Science Bulletin2008，53，20： | 8 |
| 7 | An unusual high ozone event over the North and Northeast China during the record-breaking summer in 2018显示文摘Under the background of global warming,the summer temperature of the North and Northeast China(NNEC)has significantly increased since 2017,which was accompanied by the aggravated ozone(O_(3))pollution.In 2018,the NNEC experienced a record-breaking summer of the past 40 years.Influenced by the abnormal high temperatures,a regional ozone event occurred on 2-3 August,over 63%of 79 selected cities in the NNEC were exposed to O_(3)pollution,and the maximum value of MDA8 O_(3)reached 268μg/m 3.Observations indicated that ozone concentrations agree well with the maximum temperature at 2 meters(MT2M)over NNEC with a correlation coefficient of 0.69.During the pollution episode,strong downdraft in the local high(35°N-42.5°N,112.5°E-132.5°E;LH)over the NNEC created the favourable meteorological conditions for O_(3)formation.By analyzing the horizontal wind and wave activity fluxes(WAFs)at 200 h Pa,we found that the LH formation was resulted from the Rossby wave propagation from upstream along the mid-latitude Asian jet.The split polar vortex intrusion further strengthened the amplitude of the Rossby wave and reinforced the LH.Moreover,a secondary circulation between Typhoon Jongdari and the LH contributed to the enhanced LH with strong subsidence.On the other hand,the stratospheric intrusions under the deep subsidence also contributed to the enhanced surface O_(3).In this study,the deep-seated meteorological dynamical mechanisms contributing to the abnormal high temperatures were investigated,which can lead to a better understanding of the regional O_(3)pollution over NNEC under the global-warming background. | Chuhan Lu Jia Mao Lili Wang Zhaoyong Guan Guangna Zhao Mingge Li | 2021 | Journal of Environmental Sciences2021，33，6： | 7 |
| 8 | Seismic safety of arch dams with aging effects显示文摘Arch dams suffer time-varying external loadings and harsh environment that harm their physical properties. With the aging of such dams, damage accumulates and concrete degradation inevitably appears. In this paper, a model is proposed for simulating concrete degradation with aging because of chemo-mechanical damage. The seismic response of an arch dam with aging effects is analyzed using the proposed model. The results show that the damage caused by the aging of arch dams may result in an increase in tensile cantilever stresses during earthquakes. Meanwhile, the dynamic displacement and joint opening also clearly increase in comparison with those without damage. Thus, the seismic safety of arch dams is reduced by aging effects. | WANG JinTing JIN Feng ZHANG ChuHan | 2011 | Science China(Technological Sciences)2011，54，3： | 6 |
| 9 | Bandgap prediction by deep learning in configurationally hybridized graphene and boron nitride显示文摘It is well-known that the atomic-scale and nano-scale configuration of dopants can play a crucial role in determining the electronic properties of materials.However,predicting such effects is challenging due to the large range of atomic configurations that are possible.Here,we present a case study of how deep learning algorithms can enable bandgap prediction in hybridized boron–nitrogen graphene with arbitrary supercell configurations.A material descriptor that enables correlation of structure and bandgap was developed for convolutional neural networks.Bandgaps calculated by ab initio calculations,and corresponding structures,were used as training datasets.The trained networks were then used to predict bandgaps of systems with various configurations.For 4×4 and 5×5 supercells they accurately predict bandgaps,with a R^(2) of >90% and root-mean-square error of~0.1 eV.The transfer learning was performed by leveraging data generated from small supercells to improve the prediction accuracy for 6×6 supercells.This work will pave a route to future investigation of configurationally hybridized graphene and other 2D materials.Moreover,given the ubiquitous existence of configurations in materials,this work may stimulate interest in applying deep learning algorithms for the configurational design of materials across different length scales. | Yuan Dong Chuhan Wu Chi Zhang Yingda Liu Jianlin Cheng Jian Lin | 2019 | npj Computational Materials2019，，1： | 5 |
| 10 | Detecting the Relationship Between Summer Rainfall Anomalies in Eastern China and the SSTA in the Global Domain with a New Significance Test Method显示文摘It is suggested that the multiple samples in a correlation map or a set of correlation maps should be examined with significance tests as per the Bernoulli probability model. Therefore, both the contemporaneous and lag correlations of summertime precipitation R in any one of the three regions of Northern China (NC), the Changjiang-Huaihe River Valley (CHRV), and Southern China (SC) with the SSTA in the global domain have been tested in the present article, using our significance test method and the method proposed by Livezey and Chen (1983) respectively. Our results demonstrate that the contemporaneous correlations of summer R in CHRV with the SSTA are larger than those in NC. Significant correlations of SSTA with CHRV R are found to be in some warm SST regions in the tropics, whereas those of SSTA with NC R, which are opposite in sign as compared to the SSTA-CHRV R correlations, are found to be in some regions where the mean SSTs are low. In comparison with the patterns of the contemporaneous correlations, the 1 to 12 month lag correlations between NC R and SSTA, and those between CHRV summer R and SSTA show similar patterns, including the magnitudes and signs, and the spatial distributions of the coefficients. However, the summer rainfall in SC is not well correlated with the SSTA, no matter how long the lag interval is. The results derived from the observations have set up a relationship frame connecting the precipitation anomalies in NC, CHRV, and SC with the SSTA in the global domain, which is critically useful for our understanding and predicting the climate variabilities in different parts of China. Both NC and CHRV summer R are connected with El Nio events, showing a ‘––’pattern in an El Nio year and a ‘+ +’ pattern in the subsequent year. | LU Chuhan GUAN Zhaoyong WANG Panxing DUAN Mingken | 2009 | Journal of Ocean University of China2009，8，1： | 4 |
| 11 | Interhemispheric atmospheric mass oscillation and its relation to interannual variations of the Asian monsoon in boreal summer显示文摘Using NCEP/NCAR reanalysis and precipitation records of Chinese stations, we have investigated the relationship of interhemispheric oscillation of air mass (IHO) with global lower-level circulation and monsoon anomalies in boreal summer. Our results show that the summer IHO explains a greater portion of variance in the abnormal distribution of atmospheric mass over 30°S-60°N as well as the Antarctic. The IHO strongly correlates to the variations of sea level pressure (SLP) in these regions. It is shown that IHO has some influences on both atmospheric mass transports and water vapor fluxes over 30°S-60°N in association with three anomalous cyclonic circulations over land areas of the eastern hemisphere, which is in close relation to the changes in summer monsoon intensity in eastern Asia and western Africa. Composites of summer rainfall anomalies in China for high and low IHO-index years indicate that the eastern Asian summer monsoon is more intense, with positive precipitation anomaly centers in northern and northeastern parts of China, as opposed to the negative center over the mid-lower reaches of the Yangtze River (MLRYR) in stronger IHO years. In weak IHO years, a feeble summer monsoon appears in eastern Asia, leading to positive center of precipitation anomalies displaced into the MLRYR. Furthermore, a teleconnection in wind fields between the western African and eastern Asian monsoon regions was observed in the middle and higher troposphere in the scenario of IHO. The anomalous cyclonic (anticyclonic) circulations along the path of this Africa-East Asia teleconnection were found to be just over the diabatic heating (cooling) centers, suggesting that diabatic forcings are responsible for the formation of this Africa-East Asia teleconnection. | LU ChuHan, GUAN ZhaoYong & CAI JiaXi Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China | 2010 | Science China Earth Sciences2010，53，9： | 4 |
| 12 | Applying resolved-scale linearly forced isotropic turbulence in rational subgrid-scale modeling显示文摘In previous attempts of rational subgrid-scale (SGS) modeling by employing the Kolmogorov equation of filtered (KEF) quantities, it was necessary to assume that the resolved-scale second-order structure function is stationary. Forced isotropic turbulence is often used as a framework for establishing and validating such SGS models based on stationary restrictions, for it generates statistical stationary samples. However, traditional forcing method at low wavenumbers cannot provide an analytic form of forcing term for a complete KEF in physical space, which has been illustrated to be essential in the modeling of such SGS models. Thus, an alternative forcing method giving an analytic forcing term in physical space is needed for rational SGS modeling. Giving an analytic linear driving term in physical space, linearly forced isotropic turbulence should be considered an ideal theoretical framework for rational SGS modeling. In this paper, we demonstrate the feasibility of establishing a rational SGS model with stationary restriction based on linearly forced isotropic turbulence. The performance of this rational SGS model is validated. We, therefore, propose the use of linearly forced isotropic turbulence as a complement to free-decaying isotropic turbulence and low-wavenumber forced isotropic turbulence for SGS model validations. | Chuhan Wang Mingwei Ge | 2019 | Acta Mechanica Sinica2019，35，3： | 3 |
| 13 | Accuracy of the half-power bandwidth method with a third-order correction for estimating damping in multi-DOF systems显示文摘A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems.This paper analyzes the accuracy of the half-power bandwidth method with the third-order correction in damping estimation for multi-DOF linear systems.Damping ratios in a two-DOF linear system are estimated using its displacement and acceleration frequency response curves,respectively.A wide range of important parameters that characterize the shape of these response curves are taken into account.Results show that the third-order correction may greatly improve the accuracy of the half-power bandwidth method in estimating damping in a two-DOF system.In spite of this,the half-power bandwidth method may significantly overestimate the damping ratios of two-DOF systems in some cases. | Wang Jinting Lü Dandan Jin Feng Zhang Chuhan | 2013 | Earthquake Engineering and Engineering Vibration2013，12，1： | 3 |
| 14 | Chemo-damage modeling and cracking analysis of AAR-affected concrete dams显示文摘A chemo-damage model for cracking analysis of concrete dams affected by alkali-aggregate reaction (AAR) is proposed, which combines the plastic-damage model for concrete with the AAR kinetics law. The chemo-damage model is first verified by a stress-free AAR expansion test. The expansion deformation obtained from the simulation is in good agreement with the measurement, demonstrating that the proposed model has a sufficient accuracy to predict the expansion of AAR-affected concrete. Subsequently, the expansion deformation and cracking process of the AAR-affected Fontana gravity dam is analyzed. It shows that permanent displacements in the upstream direction and the vertical direction are gradually increased during the long-term operation period, and that their maximal values reach 1.6 and 3.6 cm, respectively. A crack is observed on the wall in the foundation drainage gallery, and extends towards the downstream face of the dam. With the further development of AAR, another crack forms on the downstream face, and then intersects with the gallery crack to penetrate the downstream side profile of the dam. The third crack occurs in the upstream side wall of the gallery and propagates a short distance towards the upstream face of the dam. The simulated cracking pattern in the dam due to AAR is similar to the in situ observation. | PAN JianWen FENG YunTian XU YanJie JIN Feng ZHANG ChuHan ZHANG BingYin | 2013 | Science China(Technological Sciences)2013，56，6： | 3 |
| 15 | Closed-system burial diagenesis in reservoir sandstones:Examples from the Garn Formation at Haltenbanken area,Offshore Mid-Norway显示文摘 | Chuhan F A Bj?rlkke K Lowrey C J | 2001 | Journal of Sedimentary Research2001，71，1： | 1 |
| 16 | Closed-system burial dia genesis in reservoir sandstones:examples from the Garn Formation at Haltenbanken area, offshore mid-Norway显示文摘 | Chuhan F A Bj~rlykke K Lowrey C J | 2001 | Journal of Sedimentary Research2001，70，1： | 1 |
| 17 | Seismic fracture analysis of concrete gravity dams based on nonlinear fracture mechanics显示文摘 | Wang Guanglun Pekau O A Zhang Chuhan Wang Shaomin | 2000 | Engineering Fracture Mechanics2000，65，： | 1 |
| 18 | Application of distinct element method in dynamic analysis of high rock slopes and blocky structures显示文摘 | Zhang Chuhan O.A. Pekau Jin Feng Wang Guanglun | 1997 | Soil Dynamics and Earthquake Engineering1997，，6： | 1 |
| 19 | Endovascular treatment for pediatric intracranial aneurysms显示文摘 | Xianli LV Chuhan Jiang Youxiang Li | 2009 | Neuroradiology2009，51，11： | 1 |
| 20 | Experimental tests of rolled compacted concrete and fracture analysis of rolled compacted concrete dams显示文摘 | ZHANG Chuhan WANG Guanglun WANG Shaomin | 2002 | Journal of Ma- terials in Civil Engineering2002，14，2： | 1 |
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