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| 1 | Cryospheric Science: research framework and disciplinary system显示文摘Cryospheric changes and their impacts have received increasing concern, extending the research to include the interactions between earth spheres and the impacts of and social adaptation to cryospheric changes. As a result, Cryospheric Science is rapidly developing. However, the research framework of Cryospheric Science has not completely been set up, and the intension and extension of Cryospheric Science are unclear.Following a literature review, the research framework for Cryospheric Science and the discipline components are analysed in this paper. We consider that Cryospheric Science is an inevitable product of international research on the earth and environmental changes as well as on human sustainable development. It will not only strengthen the linkage between the cryosphere and other earth spheres by deepening traditional research areas, but will also bring more focus on the critical roles of the cryosphere in interactions between earth spheres, and will enhance the relationship between cryospheric change and climate, ecology, hydrology, surface environment and sustainable development. The disciplinary tree of Cryospheric Science is developed following the mainstream of change-impacts adaptation. The disciplines of Cryospheric Science were teased out against characteristics of traditional branches and the developing interdisciplinary branches of cryosphere elements, which will provide reference to Cryospheric Science as it systematically grows to maturity. | Dahe Qin Yongjian Ding Cunde Xiao Shichang Kang Jianwen Ren Jianping Yang Shiqiang Zhang | 2018 | National Science Review2018,5,2: | 42 |
| 2 | Estimating biophysical parameters of rice with remote sensing data using support vector machines显示文摘Hyperspectral reflectance (350-2500 nm) measurements were made over two experimental rice fields containing two cultivars treated with three levels of nitrogen application.Four different transformations of the reflectance data were analyzed for their capability to predict rice biophysical parameters,comprising leaf area index (LAI;m-2 green leaf area m-2 soil) and green leaf chlorophyll density (GLCD;mg chlorophyll m 2 soil),using stepwise multiple regression (SMR) models and support vector machines (SVMs).Four transformations of the rice canopy data were made,comprising reflectances (R),first-order derivative reflectances (D1),second-order derivative reflectances (D2),and logarithm transformation of reflectances (LOG).The polynomial kernel (POLY) of the SVM using R was the best model to predict rice LAI,with a root mean square error (RMSE) of 1.0496 LAI units.The analysis of variance kernel of SVM using LOG was the best model to predict rice GLCD,with an RMSE of 523.0741 mg m-2.The SVM approach was not only superior to SMR models for predicting the rice biophysical parameters,but also provided a useful exploratory and predictive tool for analyzing different transformations of reflectance data. | YANG XiaoHua HUANG JingFeng WU YaoPing WANG JianWen WANG Pei WANG XiaoMing Alfredo R. HUETE | 2011 | Science China(Life Sciences)2011,54,3: | 12 |
| 3 | Two-dimensional heterostructure promoted infrared photodetection devices显示文摘It is a rapidly developed subject in expanding the fundamental properties and application of two-dimensional(2D)materials.The weak van der Waals interaction in 2D materials inspired researchers to explore 2D heterostructures(2DHs)based broadband photodetectors in the far-infrared(IR)and middle-IR regions with high response and high detectivity.This review focuses on the strategy and motivation of designing 2DHs based high-performance IR photodetectors,which provides a wide view of this field and new expectation for advanced photodetectors.First,the photocarriers'generation mechanism and frequently employed device structures are presented.Then,the 2DHs are divided into semimetal/semiconductor 2DHs,semiconductor/semiconductor 2DHs,and multidimensional semi-2DHs;the advantages,motivation,mechanism,recent progress,and outlook are discussed.Finally,the challenges for next-generation photodetectors are described for this rapidly developing field. | Gaofeng Rao Xuepeng Wang Yang Wang Peihua Wangyang Chaoyi Yan Junwei Chu Lanxin Xue Chuanhui Gong Jianwen Huang Jie Xiong Yanrong Li | 2019 | InfoMat2019,1,3: | 12 |
| 4 | STUDY ON PREPARATION AND CATALYTIC ACTIVITY OF A NEW POLYMER LEWIS ACID CATALYST显示文摘This paper reports the study on the polymer protected catalyst CPVC-FeCl3 used in esterification,transesterification,synthesis of acetals or ketals and rearrangement reaction of pinacol.The catalyst has the advantages of being simple in operation,non-corrosive,easy to separate from mixtures and good reusability. | YU Shanxin and YANG Jianwen (Department of Chemistry, Hunan Normal University,Changsha, P.R.China, 410081) | 1993 | Chinese Journal of Reactive Polymers1993,2,2: | 8 |
| 5 | Finite element modeling of pore-fluid flow in the Dachang ore district,Guangxi,China:Implications for hydrothermal mineralization显示文摘当温度坡度足够地高时,在地球的上面的外壳以内在多孔的岩石和破裂中与毛孔液体的发行量联系的对流的热转移是实质的。以便在 Guangxi 的 Dachang 矿石区域理解 Sn-polymetallic 矿化作用的过程,一个有限元素方法在这研究被使用了在这个区域模仿毛孔液体流动和热转移。根据相关地质、构造、地球物理的限制,一个计算模型被建立。它使计算模拟和敏感分析能为调查可以在这个区域影响热水的矿石开始的形成矿石的毛孔液体流动和其它钥匙因素被执行。相关模拟结果显示了那:(1 ) 在矿石区域能为毛孔液体作为优先的小径服务的 Dachang 的可渗透的差错地区流动在上一地区性规模;并且(2 ) 毛孔液体流动能影响咸度分发。这个后者因素是 Sn-polymetallic 矿化作用发生在这个区域的原因的部分。 | Minghui Ju Chongbin Zhao Tagen Dai Jianwen Yang | 2011 | Geoscience Frontiers2011,2,3: | 8 |
| 6 | Finite-time stabilization of switched dynamical networks with quantized couplings via quantized controller显示文摘This paper concerns the stabilization of switched dynamical networks with logarithmic quantization couplings in a settling time.The switching sequence is constrained by hybrid dwell time. Controller is designed by using limited information. Due to the quantization and switching, traditional finite-time analysis methods cannot be utilized directly. By designing multiple Lyapunov functions and constructing comparison systems, a general criterion formulated by matrix inequalities is first given. Then specific conditions in terms of linear matrix inequalities are established by partitioning the dwell time and using convex combination technique. An optimal algorithm is proposed for the estimation of settling time. Numerical simulations are given to verify the effectiveness of the theoretical results. | YANG XinSong CAO JinDe XU Chen FENG JianWen | 2018 | Science China(Technological Sciences)2018,61,2: | 7 |
| 7 | Whole-genome sequencing provides insights into the genetic diversity and domestication of bitter gourd(Momordica spp.)显示文摘Bitter gourd(Momordica charantia)is a popular cultivated vegetable in Asian and African countries.To reveal the characteristics of the genomic structure,evolutionary trajectory,and genetic basis underlying the domestication of bitter gourd,we performed whole-genome sequencing of the cultivar Dali-11 and the wild small-fruited line TR and resequencing of 187 bitter gourd germplasms from 16 countries.The major gene clusters(Bi clusters)for the biosynthesis of cucurbitane triterpenoids,which confer a bitter taste,are highly conserved in cucumber,melon,and watermelon.Comparative analysis among cucurbit genomes revealed that the Bi cluster involved in cucurbitane triterpenoid biosynthesis is absent in bitter gourd.Phylogenetic analysis revealed that the TR group,including 21 bitter gourd germplasms,may belong to a new species or subspecies independent from M.charantia.Furthermore,we found that the remaining 166 M.charantia germplasms are geographically differentiated,and we identified 710,412,and 290 candidate domestication genes in the South Asia,Southeast Asia,and China populations,respectively.This study provides new insights into bitter gourd genetic diversity and domestication and will facilitate the future genomics-enabled improvement of bitter gourd. | Junjie Cui Yan Yang Shaobo Luo Le Wang Rukui Huang Qingfang Wen Xiaoxia Han Nansheng Miao Jiaowen Cheng Ziji Liu Changyuan Zhang Chengcheng Feng Haisheng Zhu Jianwen Su Xinjian Wan Fang Hu Yu Niu Xiaoming Zheng Yulan Yang Dai Shan Zhensheng Dong Weiming He Narinder P.S.Dhillon Kailin Hu | 2020 | Horticulture Research2020,7,1: | 7 |
| 8 | Effects of elevated atmospheric CO_2 concentration and temperature on the soil profile methane distribution and diffusion in rice–wheat rotation system显示文摘The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice–wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments:ambient conditions(CKs), CO_2 concentration elevated to ~ 500 μmol/mol(FACE),temperature elevated by ca. 2°C(T) and combined elevation of CO_2 concentration and temperature(FACE + T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE + T and T treatments, respectively, at the 7 cm depth during the rice season(p < 0.05). Mean methane diffusion effluxes to the 7 cm depth were positive in the rice season and negative in the wheat season, resulting in the paddy field being a source and weak sink, respectively. Moreover, mean methane diffusion effluxes in the rice season were 0.94, 1.19 and 1.42 mg C/(m^2·hr) in the FACE,FACE + T and T treatments, respectively, being clearly higher than that in the CK. The results indicated that elevated atmospheric CO_2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice–wheat field annual rotation ecosystem(p < 0.05). | Bo Yang Zhaozhi Chen Man Zhang Heng Zhang Xuhui Zhang Genxing Pan Jianwen Zou Zhengqin Xiong | 2015 | Journal of Environmental Sciences2015,27,6: | 5 |
| 9 | Formation and evolution of layered structure in dissimilar welded joints between ferritic-martensitic steel and 316L stainless steel with fillers显示文摘Dissimilar high-energy beam(HEB)welding is necessary in many industrial applications.Different composition of heat-affected zone(HAZ)and weld metal(WM)lead to variation in mechanical properties within the dissimilar joint,which determines the performance of the welded structure.In the present study,appropriate filler material was used during electron beam welding(EBW)to obtain a reliable dissimilar joint between reduced-activation ferritic-martensitic(RAFM)steel and 316L austenitic stainless steel.It was observed that the layered structure occurred in the weld metal with 310S filler(310S-WM),which had the inferior resistance to thermal disturbance,leading to severe hardening of 310S-WM after one-step tempering treatment.To further ameliorate the joint inhomogeneity,two-step heat treatment processes were imposed to the joints and optimized.δ-ferrite in the layered structure transformed intoγ-phase in the first-step normalizing and remained stable during cooling.In the second-step of tempering,tempered martensite was obtained in the HAZ of the RAFM steel,while the microstructure of 310S-WM was not affected.Thus,the optimized properties for HAZ and 310S-WM in dissimilar welded joint was both obtained by a two-step heat treatment.The creep failure position of two dissimilar joints both occurred in CLAM-BM. | Guoliang Liu Shanwu Yang Jianwen Ding Wentuo Han Lujun Zhou Mengqi Zhang Shanshan Zhou RDKMisra Farong Wan Chengjia Shang | 2019 | Journal of Materials Science & Technology2019,35,11: | 4 |
| 10 | Protection efficiency assessment and quality of coastal shelterbelt for Dongshan Island at the coastal section scale显示文摘The coastal shelter forest in China is under threat of destruction and degradation because of the impact of human activities. Protection efficiency assessment of the coastal shelterbelt is an important component of shelterforest remediation planning and sustainable management.In this study, a protection efficiency index(PEI) model was established using the projection pursuit method to assess the protective quality of the coastal shelter forest at the coastal section scale of Dongshan Island, China. Three criteria were used, including forest stand structure, forest belt structure, and windbreak effect; each criterion further comprised multiple factors. Based on survey data of 31 plots in the coastal shelter forest of Dongshan Island, we calculated PEI values using a projection of a pursuit model.The result showed 64.5 % of the PEIs fell at or below the middle level, which can indicate the status of the coastal shelterbelt is unsatisfactory. To further explore whether the different bays and land use types create significant differences in PEIs and evaluation indices, we used an ANOVA to test the influence of various bays and forms of land use on coastal shelterbelts. The results showed that PEI and most of the indices differed significantly by bay; mean tree height, mean DBH, mean crown width, stand density,vegetation coverage, and wind velocity reduction differed significantly by land use. Therefore, relevant measures for different locations, bays and surrounding land use can be proposed to improve the existing conditions of the coastal shelterbelt. The results of this study provide a theoretical and technical framework for future changes and sustainable management of coastal shelterbelt on Dongshan Island. | Liyun Wu Dongjin He Zhirong Ji Weibin You Yong Tan Xiaoyan Zhen Jianwen Yang | 2017 | Journal of Forestry Research2017,28,3: | 4 |
| 11 | Using Airgun Source Signals to Study Regional Wave Velocity Changes before and after the Yunlong M_S5.0 and Yangbi M_S5.1 Earthquakes显示文摘On the basis of the airgun source signals recorded by the stations from January,2016 to June,2017,we use cross-correlation detection technology to obtain the characteristics of the stable phase travel time change of each station.We used the Yunlong MS5.0 and Yangbi MS5.1 earthquakes as samples.According to regional characteristics,13 stations with high signal-to-noise ratios and complete data were selected(including 3 fixed stations and 10 active source stations).They are divided into four regions,and on the basis of the GNSS baseline data,the characteristics of regional wave velocity changes before and after the earthquake are analyzed.The results show that the station phase travel time change and the regional stress characteristics represented by the GNSS baseline data have good correlation in the short-term.Due to different degrees of regional stress,there are differences in the travel time changes of different stations in the four regions.Before the Yunlong MS5.0 and Yangbi MS5.1 earthquakes,with regional stress adjustment,there is an upward trend in the travel time changes of related stations in the adjacent areas of up to 0.02 s.The difference is that there are differences in the time nodes and duration of the travel time anomalies,and there is a reverse descent process after the Yangbi MS5.1 earthquake.There are different degrees of travel time fluctuations in the relevant stations before and after the two earthquakes,but the fluctuation range before and after the earthquake was small.Compared with the water level change of the reservoir,the adjustment of the regional stress is more likely to have a substantial impact on the travel time changes of the relevant stations. | YANG Jianwen LI Lei ZHANG Pengying YE Beng HE Yingwen CHEN Jia CHA Wenjian | 2019 | Earthquake Research in China2019,33,2: | 4 |
| 12 | Safety and efficacy of Yupingfeng granules in children with recurrent respiratory tract infection:A randomized clinical trial显示文摘Importance:Recurrent respiratory tract infection(RRTI)is common in children.Inappropriate RRTI treatment will lead to asthma and other diseases,thereby seriously affecting the growth and physical health of children.Immune function modulation can prevent and alleviate childhood RRTI.Yupingfeng(YPF),a patented traditional Chinese medicine(TCM),has immunomodulatory effects and is widely used in China to treat children with RRTI.Objective:To evaluate the safety and efficacy of YPF monotherapy in treating children with RRTI.Methods:This multicenter,randomized,double-blind,double-simulation,noninferiority clinical trial was conducted from January 2015 to August 2017,with an 8-week treatment period and 52-week follow-up after the drug withdrawal.Children aged 2–6 years with RRTI meeting the inclusion and exclusion criteria were enrolled in 13 hospitals in China and divided randomly into three groups(2:2:1 ratio)to receive YPF,pidotimod,or placebo.The primary outcome was the proportion of RRTI returning to normal standard level during the follow-up.The secondary outcomes were reduction in the number of RRTI recurrences,effect on clinical symptoms(in accord with TCM practice),effect per symptom,and safety.The trial was registered at the Chinese Clinical Trials Registry(www.chictr.org.cn)under the unique identifier ChiCTR-IPR-15006847.Results:Three hundred and fifty-one children were enrolled and randomly assigned to 3 groups;124,125,and 61 children in the YPF,pidotimod,and placebo groups,respectively,had completed the trial.During the follow-up,the proportion of RRTI returning to normal standard level was 73.13%,67.15%,and 38.81%with YPF,pidotimod,and placebo,respectively(P<0.0001).The proportion of cases who returned to normal standard level in the YPF group was 34.32%higher than that in the placebo group.The safety profile did not significantly differ among the groups.Interpretation:YPF granules were noninferior to the active control drug pidotimod oral solution for the treatment of RRTI in children,and were superior to placebo,with a high safety profile. | Baoping Xu Xinmin Li Siyuan Hu Yixiao Bao Fengmei Chen Zhimin Chen Yonggang Du Enmei Liu Yufeng Liu Qinghui Mou Baoling Su Bo Wang Jianwen Xu Guiping Xu Qiaozhi Yang Liwei Gao Xiaohui Liu Lei Li Rong Ma Kunling Shen | 2022 | Pediatric Investigation2022,6,2: | 3 |
| 13 | Analysis of Ground Motion Attenuation Characterization for Moderate Earthquakes in the Sichuan-Yunnan Region显示文摘The ground motion attenuation models for PGA,PGV and response spectrum at rock sites and soils sites are derived separately from the digital strong motion records of moderate earthquakes in the Sichuan-Yunnan region after 2007. By comparison with Yu Yanxiangs attenuation model for rock sites in western China,reliability of the model is verified for moderate earthquake. According to the distribution of strong motion data against magnitude and epicentral distance,the applicability and reliability of the results in this paper are discussed. | Yu Tian Cui Jianwen Li Xiaojun Yang Liwei | 2015 | Earthquake Research in China2015,29,2: | 3 |
| 14 | CATALYTIC ESTERIFICATION OF CARBOXYLIC ACIDS WITH ALCOHOLS BY SULFO-POLYVINYL CHLORIDE显示文摘Polyvinyl Chloride reacted with chlorosulfonic acid to from a polymer catalyst PVC-SO3H.This polymer catalyst was found to have high activity for resterification reaction between carboxylic acids and alcohols.This paper deals with the conditions in synthesis of n-butlyacetate catalyzed with PVC-SO3H.The PVC-SO3H was used as a catalyst for preparing 11 esters of acetic acid,propionic acid and butyric acid with the yields of 82-92%. | Yu Shanxin ZHAO Zongbao YANG Jianwen (Department of Chemistry, Hunan Normal University, Changsha 410081, China) | 1993 | Chinese Journal of Reactive Polymers1993,2,2: | 3 |
| 15 | Digital fixed-frequency hysteresis current control of a BLDC motor applied for aerospace electrically powered actuators显示文摘In the conventional cascade control structure of aerospace electrically powered actuators, the current(or electromagnetic torque) loop plays a critical role in realizing a rapid response for a digitally controlled Brush Less Direct Current(BLDC) motor. Hysteresis Current Control(HCC) is an effective method in improving the performance of current control for a BLDC motor.Nevertheless, the varying modulating frequency in the traditional HCC causes severe problems on the safety of power devices and the electromagnetic compatibility design. A triangular carrier-based fixed-frequency HCC strategy is expanded by relaxing the constraints on the rising and descending rates of the winding current to advance the capability of HCC to realize fixed-frequency modulation in the steady state. Based on that, a new flexible-bound-size quasi-fixed-frequency HCC is proposed, and the range feasible to realize fixed-frequency modulation control can cover the entire running process in the steady state. Meanwhile, a corresponding digital control strategy is designed,and four digitalization rules are proposed to extend the capacity to achieve fixed-frequency modulation control to the unsteady working state, that is, a novel fixed-frequency modulation is realized.Simulation and experimental results prove the effectiveness of this improved fixed-frequency HCC strategy. | Jian FU Yongling FU Liming YU Jianwen GUO Rongrong YANG Mingkang WANG | 2018 | Chinese Journal of Aeronautics2018,31,6: | 3 |
| 16 | Practice and understanding of developing new technologies and equipment for green and low-carbon production of oilfields显示文摘The core of China’s low-carbon development includes optimization of industrial structure,clean energy technologies,emission reduction technologies,and innovation of relevant systems and institutions.China National Petroleum Corporation(CNPC)has always been a proactive participant in developing low-carbon economy,shouldering the responsibilities of safeguarding oil and gas supply,conserving energy,and reducing emission.Therefore,CNPC fulfills those responsibilities as a substantial part of its overall strategy.Guided by low carbon and driven by innovation,petroleum corporations have taken constant innovation of low-carbon technologies,especially the development of green and low-carbon petroleum engineering technologies and equipment,as major measures for energy conservation and emission reduction.Large-scale development mode o f unconventional resource anhydrous fracturing should be innovated.And supercritical C 02 should be used to replace water for fracturing operation,in order to achieve multiple objectives of C 02 burying,conserve water resource,improve single well production and ultimate recovery,realizing reduced emission and efficient utilization o f C 02 resources.Artificial lifting energy-saving and efficiencyincreasing technologies and injection-production technology in the same well should also be innovated.Energy consumption of high water-cut wells is reduced to support the new low-carbon operation mode of high water-cut oilfields and realize energy saving and efficiency improvement during oil production by developing the operation efficiency of the lifting system and reducing the ineffective lifting of formation water.These technologies have been widely recognized by local and international experts and have greatly enhanced CNPC's international influence.This study expounds the key technologies and equipment with regard to the development of green and low-carbon petroleum engineering and provide relevant suggestions. | He LIU Jianwen YAN Siwei MENG Qinghai YANG Zixiu YAO Shijia ZHU | 2019 | Frontiers of Engineering Management2019,6,4: | 3 |
| 17 | On the role of buoyancy force in the ore genesis of SEDEX deposits:Example from Northern Australia显示文摘Finite element modeling on a highly conceptualized 2-D model of fluid flow and heat transport is un-dertaken to simulate the paleo-hydrological system as if the Mount Isa deposits were being formed in the Mount Isa basin, Northern Australia, and to evaluate the potential of buoyancy force in driving ba-sin-scale fluid flow for the formation of sedimentary-exhalative (SEDEX) deposits. Our numerical case studies indicate that buoyancy-driven fluid flow is controlled mainly by the fault penetration depth and its spatial relation with the aquifer. Marine water recharges the basin via one fault and flows through the aquifer where it is heated from below. The heated metalliferous fluid discharges to the basin floor via the other fault. The venting fluid temperatures are computed to be in the range of 115 to 160℃, with fluid velocities of 2.6 to 4.1 m/year over a period of 1 Ma. These conditions are suitable for the formation of a Mount Isa-sized zinc deposit, provided a suitable chemical trap environment is present. Buoyancy force is therefore a viable driving mechanism for basin-scale ore-forming hydrothermal fluid migration, and it is strong enough to lead to the genesis of supergiant SEDEX deposits like the Mount Isa deposit, Northern Australia. | YANG JianWen FENG ZuoHai LUO XianRong CHEN YuanRong | 2009 | Science China Earth Sciences2009,52,4: | 3 |
| 18 | Strongly coupled Te-SnS_(2)/MXene superstructure with self-autoadjustable function for fast and stable potassium ion storage显示文摘Potassium-ion batteries(PIBs)are a promising candidate for next-generation electric energy storage applications because of the abundance and low cost of potassium.However,the development of PIBs is limited by sluggish kinetics and huge volume expansion of anodes,leading to poor rate capability and cycling stability.Herein,an advanced superstructure anode,including Te-doped SnS_(2) nanosheets uniformly anchored on MXene surface(Te-SnS_(2)/MXene),is rationally designed for the first time to boost K^(+)storage performance.Featuring with strong interface interaction and self-autoadjustable interlayer spacings,the Te-SnS_(2)/MXene can efficiently accelerate electron/ion transfer,accommodate volume expansion,inhibit crack formation,and improve pseudocapacitive contribution during cycling.Thus,the novel Te-SnS_(2)/MXene anode delivers a high reversible capacity(343.2 mAh g^(-1) after 50 cycles at0.2 A g^(-1)),outstanding rate capability(186.4 mAh g^(-1) at 20 A g^(-1)),long cycle stability(165.8 mAh g^(-1)after 5000 cycles at 10 A g^(-1) with a low electrode swelling rate of only 15.4%),and reliable operation in flexible full battery.The present Te-SnS_(2)/MXene becomes among the best transition metal-based anode materials for PIBs reported to date. | Hongyang Sun Yelong Zhang Xiaodan Xu Jianwen Zhou Fan Yang Hao Li Hao Chen Yucheng Chen Zheng Liu Zhenping Qiu Da Wang Lipo Ma Jiawei Wang Qingguang Zeng Zhangquan Peng | 2021 | Journal of Energy Chemistry2021,30,10: | 2 |
| 19 | Preparation of basic lead oxide from spent lead acid battery paste via chemical conversion显示文摘 | Xinfeng Zhu Lei Li Xiaojuan Sun Danni Yang Linxia Gao Jianwen Liu R. Vasant Kumar Jiakuan Yang | 2012 | Hydrometallurgy2012,,: | 2 |
| 20 | Numerically quantifying the relative importance of topography and buoyancy in driving groundwater flow显示文摘Both topography and buoyancy can drive groundwater flow;however,the interactions between them are still poorly understood.In this paper,the authors conduct numerical simulations of variable-density fluid flow and heat transport to quantify their relative importance.The finite element modeling experiments on a 2-D conceptual model reveal that the pattern of groundwater flow depends largely upon the relative magnitude of the flow rate due to topography alone and the flow rate due to buoyancy alone.When fluid velocity due to topography is greater than that due to buoyancy at large water table gradients,topography-driven 'forced convection' overwhelms buoyancy-driven 'free convection'.When flow velocity due to buoyancy is greater than that due to topography at small water table gradients,mixed free and forced convection takes place.In this case,free convection becomes dominant,but topography-driven flow still plays an important role since it pushes the free convection cells to migrate laterally in the downhill direction.Consequently,hydrothermal fluid flow remains changing periodically with time and no steady state can be reached.The presence of a low-permeability layer near the surface helps eliminate the topography effect on the underlying free convection. | YANG JianWen 1,2,FENG ZuoHai 1,LUO XianRong 1 & CHEN YuanRong 1 1 Faculty of Earth Sciences,Guilin University of Technology,Guilin 541004,China 2 Department of Earth and Environmental Sciences,University of Windsor,Windsor,Ontario,N9B 3P4,Canada | 2010 | Science China Earth Sciences2010,53,1: | 2 |