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矿山帷幕强动水通道注浆控制技术及工程应用 被引量:13
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作者 杨柱 赵恰 黄炳仁 《矿业研究与开发》 CAS 北大核心 2020年第12期117-121,共5页
矿山帷幕是大水矿山地下水治理的有效手段,而岩溶强动水通道的有效封堵直接决定帷幕工程的堵水效果。结合凡口铅锌矿第5段帷幕工程,采用示踪试验、加密钻探等手段查明待注岩溶通道的特征及地下水流速;基于地下水动力学及渗流理论,推导... 矿山帷幕是大水矿山地下水治理的有效手段,而岩溶强动水通道的有效封堵直接决定帷幕工程的堵水效果。结合凡口铅锌矿第5段帷幕工程,采用示踪试验、加密钻探等手段查明待注岩溶通道的特征及地下水流速;基于地下水动力学及渗流理论,推导得出骨料在地下水中的运动状态下的参数方程,以此计算骨料投放量。最终采用投注骨料、注入快凝膨胀材料、双液浆、最后普通水泥浆加固的4步动水注浆方案,一次性封堵过水量6000m^3/d的强动水通道。帷幕堵水率从67%提升至75%,年节省排水电费698.16万元。该技术可供类似帷幕工程强动水注浆施工借鉴。 展开更多
关键词 矿山帷幕 岩溶通道 强动水 注浆
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Dynamic tensile strength and failure mechanisms of thermally treated sandstone under dry and water-saturated conditions 被引量:8
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作者 Pin WANG Tu-bing YIN Bi-wei HU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第8期2217-2238,共22页
To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandston... To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandstone under dry and water-saturated conditions.Experimental results showed that high temperatures effectively weakened the tensile strength of sandstone specimens,and the P-wave velocity declined with increasing temperature.Overall,thermal damage of rock increased gradually with increasing temperature,but obvious negative damage appeared at the temperature of 100℃.The water-saturated sandstone specimens had lower indirect tensile strength than the dry ones,which indicated that water-rock interaction led to secondary damage in heat-treated rock.Under both dry and water-saturated conditions,the dynamic tensile strength of sandstone increased with the increase of strain rate.The water-saturated rock specimens showed stronger rate dependence than the dry ones,but the loading rate sensitivity of thermally treated rock decreased with increasing treatment temperature.With the help of scanning electron microscopy technology,the thermal fractures of rock,caused by extreme temperature,were analyzed.Hydro-physical mechanisms of sandstone under different loading rate conditions after heat treatment were further discussed. 展开更多
关键词 SANDSTONE dynamic tensile strength hydro-thermal coupling damage loading rate dependence failure mechanism
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Immersible ergocycle prescription as a function of relative exercise intensity
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作者 Mauricio Garzon Mathieu Gayda +2 位作者 Anil Nigam Alain-Steve Comtois Martin Juneau 《Journal of Sport and Health Science》 SCIE 2017年第2期219-224,共6页
Purpose: The purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake(%VO_(2max)), percentage of maximal heart rate(%HR_(ma... Purpose: The purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake(%VO_(2max)), percentage of maximal heart rate(%HR_(max)), %VO_2 reserve(%VO_2R), and %HR reserve(%HRR)) in order to obtain the more appropriate method for exercise intensity prescription when using an immersible ergocycle(IE) and to propose a prediction equation to estimate oxygen consumption(VO_2) based on IE pedaling rate(rpm) for an individualized exercise training prescription.Methods: Thirty-three healthy participants performed incremental exercise tests on IE and dryland ergocycle(DE) at equal external power output(Pext). Exercise on IE began at 40 rpm and was increased by 10 rpm until exhaustion. Exercise on DE began with an initial load of 25 W and increased by 25 W/min until exhaustion. VO_2 was measured with a portable gas analyzer(COSMED K4b^2) during both incremental tests. On IE and DE, %VO_2R, %HRmax, and %HRR at equal Pext did not differ(p > 0.05).Results: The %HRR vs. %VO_2R regression for both IE and DE did not differ from the identity line %VO_2R IE = 0.99 × HRR IE(%) + 0.01(r^2= 0.91, SEE = 11%); %VO_2R DE = 0.94 × HRR DE(%) + 0.01(r^2= 0.94, SEE = 8%). Similar mean values for %HRmax, %VO_2R, and %HRR at equal Pext were observed on IE and DE. Predicted VO_2 obtained according to rpm on IE is represented by: VO_2(L/min) = 0.000542 × rpm2-0.026 × rpm + 0.739(r = 0.91, SEE = 0.319 L/min).Conclusion: The %HRR–%VO_2R relationship appears to be the most accurate for exercise training prescription on IE. This study offers new tools to better prescribe, control, and individualize exercise intensity on IE. 展开更多
关键词 Exercise prescription Heart rate Immersed ergocycle Oxygen uptake Pedaling rate
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Effective approaches to extending medium-term forecasting of persistent severe precipitation in regional models
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作者 WANG Dong-Hai ZHAO Yan-Feng 《Atmospheric and Oceanic Science Letters》 CSCD 2018年第2期150-156,共7页
A set of methods designed to improve (i.e.extend) the medium-term forecasting of persistent severe rainfall (PSR) events in China using the regional Weather Research and Forecasting model are summarized.Simulation... A set of methods designed to improve (i.e.extend) the medium-term forecasting of persistent severe rainfall (PSR) events in China using the regional Weather Research and Forecasting model are summarized.Simulations show that achieving a more efficient use of large-scale atmospheric variations of the global model and retaining small-scale features in the regional model are critical for better forecasting PSR events.For precipitation,the larger the magnitude and longer the lead time,the more significant the improvement-especially for the methods of spectral nudging and updated initial conditions.In terms of large-scale circulation,the anomaly correlation coefficient can be distinctly improved for 1-5-day lead times by adopting the spectral nudging technique,whereas lateral boundary filtering results in marked improvement for 7-11-day lead times. 展开更多
关键词 Persistent severeprecipitation dynamicextended medium-termforecasting spectralnudging lateral boundaryfiltering updated initialconditions
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Controlled low-strength material incorporating recycled fine aggregate from urban red brick based construction waste 被引量:9
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作者 Ran Jin Zhang Jinxi +2 位作者 Yang Mijia Jia Dongdong Lu Shengdi 《Journal of Southeast University(English Edition)》 EI CAS 2017年第4期496-501,共6页
Sixteen controlled low-strength material( CLSM)mixtures with various cement-to-sand( C/Sa) ratios and water-to-solid( W/So) ratios were prepared using recycled fine aggregate from urban red brick based construction wa... Sixteen controlled low-strength material( CLSM)mixtures with various cement-to-sand( C/Sa) ratios and water-to-solid( W/So) ratios were prepared using recycled fine aggregate from urban red brick based construction waste.The fluidity and bleeding of the fresh CLSM mixtures were measured via the modified test methods, and the hardened CLSM mixtures were then molded to evaluate their compressive strength and durability. The results showthat the fluidity of the fresh CLSM mixtures is 105 to 227 mm with the corresponding bleeding rate of 3. 7% to 15. 5%, which increases with the increase in fluidity. After aging for 28 d,the compressive strength of the hardened CLSM mixtures reaches 1. 15 to 13. 96 M Pa, and their strength can be further enhanced with longer curing ages. Additionally, the strength increases with the increase of the C/Sa ratio, and decreases with the increase of the W/So ratio under the same curing age. Based on the obtained compressive strength, a fitting model for accurately predicting the compressive strength of the CLSM mixtures was established, which takes into account the above two independent variables( C/Sa and W/So ratios).M oreover, the durability of the hardened CLSM mixtures is enhanced for samples with higher C/Sa ratios. 展开更多
关键词 controlled low-strength material recycled fine aggregate fo m urban red brick based construction waste fluidity bleeding compressive strength durability
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Subsurface Flow Processes in Sloping Cropland of Purple Soil 被引量:7
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作者 TANG Jialilang ZHU Bo +3 位作者 WANG Tao CHENG Xunqiang GAO Meirong LIN Henry 《Journal of Mountain Science》 SCIE CSCD 2012年第1期1-9,共9页
Subsurface flow is a prominent runoff process in sloping lands of purple soil in the upper Yangtze River basin.However,it remains difficult to identify and quantify.In this study,in situ runoff experimental plots were... Subsurface flow is a prominent runoff process in sloping lands of purple soil in the upper Yangtze River basin.However,it remains difficult to identify and quantify.In this study,in situ runoff experimental plots were used to measure soil moisture dynamics using an array of time domain reflectometry(TDR) together with overland flow and subsurface flow using isolated collecting troughs.Frequency of preferential flow during rainfall events and the controls of subsurface flow processes were investigated through combined analysis of soil properties,topography,rainfall intensity,initial wetness,and tillage.Results showed that subsurface flow was ubiquitous in purple soil profiles due to welldeveloped macropores,especially in surface soils while frequency of preferential flow occurrence was very low(only 2 cases in plot C) during all 22 rainfall events.Dry antecedent moisture conditions promoted the occurrence of preferential flow.However,consecutive real-time monitoring of soil moisture at different depths and various slope positions implied the possible occurrence of multiple subsurface lateral flows during intensive storms.Rainfall intensity,tillage operation,and soil properties were recognized as main controls of subsurface flow in the study area,which allows the optimization of management practices for alleviating adverse environmental effects of subsurface flow in the region. 展开更多
关键词 Subsurface lateral flow Purple soil Soil moisture Sloping land Land use
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Study on Hydrography and Small-Scale Process over Zhoushan Sea Area
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作者 WU He DU Min +1 位作者 WANG Xiaoyong MENG Jie 《Journal of Ocean University of China》 SCIE CAS 2015年第5期829-834,共6页
This paper mainly analyzes the tidal characteristics and small-scale mixing process near Zhoushan Islands. First, the spectral analysis and wavelet analysis are adopted for the measured tide level data and tidal curre... This paper mainly analyzes the tidal characteristics and small-scale mixing process near Zhoushan Islands. First, the spectral analysis and wavelet analysis are adopted for the measured tide level data and tidal current data from the Zhoushan sea area, which indicate that the main tidal cycle near Hulu Island and Taohua Island is semi-diurnal cycle, the diurnal cycle is subordinate. Both their intensities are changed periodically, meanwhile, the diurnal tide becomes stronger when semi-diurnal tide becomes weak. The intensity of baroclinie tidal current weakens at first and then strengthens from top to bottom. Then, in this paper, the Gregg-Henyey (G-H) parameterization method is adopted to calculate the turbulent kinetic energy dissipation rate based on the measured temperature and tidal current data. The results of which shown that the turbulent kinetic energy dissipation rate around Hulu Island is higher than that around Taohua Island. In most cases, the turbulent kinetic energy dissipation rate during spring tide is larger than that during the neap tide; the turbulent kinetic energy dissipation rate in the surface layer and the bottom layer are higher than that in the intermediate water; the changes of turbulent kinetic energy dissipation rate and tidal current are basically synchronous The modeled turbulent kinetic energy dissipation rate gets smaller with the increase of the stratification, however, gets larger with the increase of shearing. 展开更多
关键词 tidal characteristics parameterization method turbulent kinetic energy dissipation rate
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A numerical study on heat transfer enhancement and design of a heat exchanger with porous media in continuous hydrothermal flow synthesis system 被引量:2
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作者 Pedram Karimi Pour-Fard Ebrahim Afshari +1 位作者 Masoud Ziaei-Rad Shahed Taghian-Dehaghani 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第10期1352-1359,共8页
The aim of this study is to use a new configuration of porous media in a heat exchanger in continuous hydrothermal flow synthesis(CHFS)system to enhance the heat transfer and minimize the required length of the heat e... The aim of this study is to use a new configuration of porous media in a heat exchanger in continuous hydrothermal flow synthesis(CHFS)system to enhance the heat transfer and minimize the required length of the heat exchanger.For this purpose,numerous numerical simulations are performed to investigate performance of the system with porous media.First,the numerical simulation for the heat exchanger in CHFS system is validated by experimental data.Then,porous media is added to the system and six different thicknesses for the porous media are examined to obtain the optimum thickness,based on the minimum required length of the heat exchanger.Finally,by changing the flow rate and inlet temperature of the product as well as the cooling water flow rate,the minimum required length of the heat exchanger with porous media for various inlet conditions is assessed.The investigations indicate that using porous media with the proper thickness in the heat exchanger increases the cooling rate of the product by almost 40% and reduces the required length of the heat exchanger by approximately 35%.The results also illustrate that the most proper thickness of the porous media is approximately equal to 90% of the product tube's thickness.Results of this study lead to design a porous heat exchanger in CHFS system for various inlet conditions. 展开更多
关键词 Continuous hydrothermal flow synthesis Heat exchanger Heat transfer enhancement Porous media Numerical simulation
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Study on the Recurrence Probability of Strong Earthquakes of Faults
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作者 Zhu Yuanqing Xie Chaodi +1 位作者 Song Xiuqing Qin Haowen 《Earthquake Research in China》 2014年第2期152-163,共12页
Based on the physical model of Brownian passage time,the probabilities of recurrence of strong earthquakes on the major active faults in China are calculated in different predictive time spans,based mainly on the anal... Based on the physical model of Brownian passage time,the probabilities of recurrence of strong earthquakes on the major active faults in China are calculated in different predictive time spans,based mainly on the analysis of the earthquake preparation process before a strong earthquake occurs. Furthermore,the seismic risks on active faults are studied. The results show that the earthquake probabilities on the Xianshuihe fault,the Altyn Tagh fault,the east Kunlun fault and Xiaojiang fault are significantly greater than other faults in the Chinese mainland,which indicates that the level of stress accumulation on these faults are higher than on other faults. Therefore,these faults may have a seismic risk for strong earthquake in future. 展开更多
关键词 Seismic risk Brownian passage time model Conditional probability FAULT Earthquake recurrence
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Modeling stationary and moving cracks in shells by X-FEM with CB shell elements 被引量:7
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作者 ZENG QingLei LIU ZhanLi +1 位作者 XU DanDan ZHUANG Zhuo 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第7期1276-1284,共9页
The continuum-based(CB)shell theory is combined with the extended finite element method(X-FEM)in this paper to model crack propagation in shells under static and dynamic situations.Both jump function and asymptotic cr... The continuum-based(CB)shell theory is combined with the extended finite element method(X-FEM)in this paper to model crack propagation in shells under static and dynamic situations.Both jump function and asymptotic crack tip solution are adopted for describing the discontinuity and singularity of the crack in shells.Level set method(LSM)is used to represent the crack surface and define the enriched shape functions.Stress intensity factors(SIFs)are calculated by the displacement interpolation technique to prove the capability of the method and the maximum strain is applied for the fracture criterion.Also,an efficient integration scheme for the CB shell element with cracks is proposed. 展开更多
关键词 CB shell element X-FEM level set method crack propagation
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Atomic resolution scanning tunneling microscope imaging up to 27 T in a water-cooled magnet 被引量:2
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作者 Wenjie Meng Ying Guo +1 位作者 Yubin Hou Qingyou Lu 《Nano Research》 SCIE EI CAS CSCD 2015年第12期3898-3904,共7页
We report the first atomically resolved scanning tunneling microscope (STM) imaging in a water-cooled magnet (WM), for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM f... We report the first atomically resolved scanning tunneling microscope (STM) imaging in a water-cooled magnet (WM), for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM features an ultra-rigid and compact scan head in which the coarse approach is driven by our newly designed TunaDrive piezoelectric motor. A three-level spring hanging system is used for vibration isolation. Room-temperature raw-data images of graphite with quality atomic resolution were acquired in the presence of very strong magnetic fields, with a field strength up to 27 T, in a 32-mm-diameter bore WM with a maximum field strength of 27.5 T at a power rating of 10 MW, calibrated by nuclear magnetic resonance (NMR). This record field strength of 27 T exceeds the maximal field strength achieved by the conventional supercon- ducting magnets. Besides, our WM-STM has paved the way to STM imaging using a 45 T, 32-mm-diameter bore hybrid magnet, which is the world's flagship magnet, producing the strongest steady magnetic field. 展开更多
关键词 scanning tunnelingmicroscopy water-cooled magnet strong magnetic field TunaDriver piezoelectricmotor highly oriented pyrolyticgraphite
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Phase transformation and shape evolution of iron oxide nanocrystals synthesized in the ethylene glycol-water system
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作者 LIU RongZheng ZHAO YuZhen +2 位作者 HUANG RongXia ZHAO YongJie ZHOU HePing 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第7期1271-1276,共6页
Iron oxide particles with various shapes,sizes and phase concentrations(including--Fe2O3 and Fe3O4) have been synthesized through a simple hydrothermal method in the ethylene glycol(EG)-water system.In the preparation... Iron oxide particles with various shapes,sizes and phase concentrations(including--Fe2O3 and Fe3O4) have been synthesized through a simple hydrothermal method in the ethylene glycol(EG)-water system.In the preparation conditions,ferric chloride(FeCl3.6H2O) was used as the iron source in the presence of sodium hydroxide(NaOH) without any surfactants.By adjusting the experimental parameters(EG/H2O ratio,base content,iron ions concentration,etc.),the shape,the size,the phase and the magnetic property of the products could be easily controlled.The products were characterized by using X-ray diffraction(XRD),scanning electron microscopy(SEM),and a vibrating sample magnetometer(VSM).A further investigation revealed that high EG content and high alkaline condition favored the formation of Fe3O4 phase.A possible growth mechanism was proposed based on the experimental results.The magnetic properties were deeply affected by the morphology and phase of the as-synthesized products.The controlled shape,size and phase structure of the iron oxides through simple synthetic procedures provides potential opportunities to realize the promising size and shape-dependent applications. 展开更多
关键词 iron oxide SHAPE SIZE phase transformation magnetic property
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