Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy ...Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.展开更多
On the basis of computational fluid dynamics,the flow field characteristics of multi-trophic artificial reefs,including the flow field distribution features of a single reef under three different velocities and the ef...On the basis of computational fluid dynamics,the flow field characteristics of multi-trophic artificial reefs,including the flow field distribution features of a single reef under three different velocities and the effect of spacing between reefs on flow scale and the flow state,were analyzed.Results indicate upwelling,slow flow,and eddy around a single reef.Maximum velocity,height,and volume of upwelling in front of a single reef were positively correlated with inflow velocity.The length and volume of slow flow increased with the increase in inflow velocity.Eddies were present both inside and backward,and vorticity was positively correlated with inflow velocity.Space between reefs had a minor influence on the maximum velocity and height of upwelling.With the increase in space from 0.5 L to 1.5 L(L is the reef lehgth),the length of slow flow in the front and back of the combined reefs increased slightly.When the space was 2.0 L,the length of the slow flow decreased.In four different spaces,eddies were present inside and at the back of each reef.The maximum vorticity was negatively correlated with space from 0.5 L to 1.5 L,but under 2.0 L space,the maximum vorticity was close to the vorticity of a single reef under the same inflow velocity.展开更多
In this study, characteristics of flow field and wave propagation near submerged breakwater on a sloping bed are investigated with numerical model. The governing equations of the vertical two-dimensional model are Rey...In this study, characteristics of flow field and wave propagation near submerged breakwater on a sloping bed are investigated with numerical model. The governing equations of the vertical two-dimensional model are Reynolds Averaged Navier Stokes equations. The Reynolds stress terms are closed by a nonlinear k - ε turbulence transportation model. The free surface is traced through the PILC-VOF method. The proposed numerical model is verified with experimental results. The numerical result shows that the wave profile may become more asymmetrical when wave propagates over breakwater. When wave crest propagates over breakwater, the anticlockwise vortex may generate. On the contrary, when wave hollow propagates over breakwater, the clockwise vortex may generate. Meanwhile, the influenced zone of vortex created by wave crest is larger than that created by wave hollow. All the maximum values of the turbulent kinetic energy, turbulent dissipation and eddy viscosity occur on the top of breakwater. Both the turbulent dissipation and eddy viscosity increase as the turbulent kinetic energy increases. Wave energy may rapidly decrease near the breakwater because turbulent dissipation increases and energy in lower harmonics is transferred into higher harmonics.展开更多
A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Ru...A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Rushton turbine. The power consumption and flow field characteristics of the coaxial mixer in laminar and transitional flow are simulated numerically, and then the distribution of velocity field, shear rate and mass flow rate are analyzed. The simulation results indicate that the outer frame has little effect on the power consumption of the double inner impeller whether in laminar or transitional flow, whereas the inner combined impeller has a great effect on the power consumption of the outer frame. Compared with the single rotation mode, the power consumption of the outer frame will decrease in co-rotation mode and increase in counter-rotation mode. The velocity, shear rate and mass flow rate are relatively high near the inner impeller in all operating modes, and only under double-shaft agitation will the mixing performance near the free surface be improved.In addition, these distributions in the co-rotation and counter-rotation modes show little difference, but the co-rotation mode is recommended for the advantage of low power consumption.展开更多
The overburden failure causes the changes of the constant electric field, and the resistivity is the main parameter in these changes. The experimental simulation about tbe response relation between the overburden fail...The overburden failure causes the changes of the constant electric field, and the resistivity is the main parameter in these changes. The experimental simulation about tbe response relation between the overburden failure and its electrical parameter changes is made by building the similar material physics model of mining. The experiment results are used to analyze and test the in-situ detection. The research indicates that the resistivity changes with the electric characteristic of the rock in cracked zone and caving zone caused by overburden failure, the response characteristics of resistivity vary with the failure degrees at different overburden failure zone and that they are corresponding. The resistivity method used in monitoring the overburden failure can determine the height and the affecting scopes of the cracked zone and caving zone. This can provide reliable techaological guarantee for mining design and safe production.展开更多
The turbo air classifier is widely used powder classification equipment in a variety of fields. The flow field characteristics of the turbo air classifier are important basis for the improvement of the turbo air class...The turbo air classifier is widely used powder classification equipment in a variety of fields. The flow field characteristics of the turbo air classifier are important basis for the improvement of the turbo air classifier＇s structural design. The flow field characteristics of the rotor cage in turbo air classifiers were investigated trader different operating conditions by laser Doppler velocimeter（LDV）, and a measure diminishing the axial velocity is proposed. The investigation results show that the tangential velocity of the air flow inside the rotor cage is different from the rotary speed of the rotor cage on the same measurement point due to the influences of both the negative pressure at the exit and the rotation of the rotor cage. The tangential velocity of the air flow likewise decreases as the radius decreases in the case of the rotor cage＇s low rotary speed. In contrast, the tangential velocity of the air flow increases as the radius decreases in the case of the rotor cage＇s high rotary speed. Meanwhile, the vortex inside the rotor cage is found to occur near the pressure side of the blade when the rotor cage＇s rotary speed is less than the tangential velocity of air flow. On the contrary, the vortex is found to occur near the blade suction side once the rotor cage＇s rotary speed is higher than the tangential velocity of air flow. Inside the rotor cage, the axial velocity could not be disregarded and is largely determined by the distances between the measurement point and the exit.展开更多
The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-εturbulence model,and compared with the ...The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-εturbulence model,and compared with the results of dedicated rock breaking drilling experiments.The numerical results show that the nozzle velocity and dynamic pressure of the nozzle decrease with an increase in the jet distance,and the axial velocity of the nozzle decays regularly with an increase in the dimensionless jet distance.Moreover,the axial velocity related to the nozzle with inclination angle 20°and 30°can produce a higher hole depth,while the radial velocity of the nozzle with 60°inclination can enlarge the hole diameter.The outcomes of the CFD simulations are consistent with the actual dynamic rock breaking and pore forming process,which lends credence to the present results and indicates that they could be used as a reference for the future optimization of systems based on the multi-hole combined external rotary bit technology.展开更多
The change rules of displacement field characteristics of coal seam and tunners surrounding rock were obtained by means of numerical simulation-FLAC^3D and site observation, and according to engineering geology and ex...The change rules of displacement field characteristics of coal seam and tunners surrounding rock were obtained by means of numerical simulation-FLAC^3D and site observation, and according to engineering geology and exploitation technology of 1151 （3） fully mechanized top coal caving （FMTC） face in Xieqiao colliery. The research＇s results show that the top coal displacement on the top of FMTC face is apparently larger than those of the middle and the bottom, the top coal begins to move in the front of the face＇s wall, and the sub-level top coal-rock moves ahead of the low-level top coal-rock, the vertical displacement of top coal-rock increases gradually as the decreasing of distance to face Top coal and overlying strata in vertical direction are always in compressed state in the front of face, then the top coal begins to separate from the overlying strata at the upside of face. The support loading at face is mainly the deformation pressure due to top coal and main roof＇s movement, and it is not suitable for the FMTC face with traditional support design. Surrounding rock movement of the face is of near-field effect, the surrounding rock deformation is acute greatly near to the face, the ideas of supporting design for the tailentry and headentry should be changed from loading control to deformation control.展开更多
The installed porcelain insulators on existing railway lines in China are prone to“snow flash”in winter.In order to prevent the occurrence of“snow flash”and improve the reliability of the insulators,a composite-po...The installed porcelain insulators on existing railway lines in China are prone to“snow flash”in winter.In order to prevent the occurrence of“snow flash”and improve the reliability of the insulators,a composite-porcelain insulator is designed.A multi-physics coupling simulation model is built based on numerical simulation methods of the electromagnetic field theory and computational fluid dynamics.Taking average electric field intensity on the surface of the insulator as the characteristic parameter of the electric field distortion degree and the snow crystal collision coefficient and distribution coefficient as the characteristic parameter of snow crystal deposition,the characteristics of snow crystal deposition under different wind speeds and wind direction angles and the electric field characteristics under two snow cover types are analyzed.The simulation results show that the average electric field intensity of composite-porcelain insulators is 10.4%and 13.8%,respectively,lower than that of porcelain insulators in vertical and horizontal wind snow covers,which can effectively reduce the degree of electric field distortion.The collision coefficient of snow crystals on the surface of the composite-porcelain insulator sheds is 16.0%higher than that of the porcelain insulator,and the collision coefficient of the trunk and the fittings are lower 20.2%and 11.9%than that of the porcelain insulator.There is almost no change in the distribution coefficient of the insulator sheds.展开更多
In order to research the field sensing characteristic of the carbon fiber smart material, the Tikhonov regularization principle and the modified Newton-Raphson(MNR) algorithm were adopted to solve the inverse problem ...In order to research the field sensing characteristic of the carbon fiber smart material, the Tikhonov regularization principle and the modified Newton-Raphson(MNR) algorithm were adopted to solve the inverse problem of the electrical resistance tomography(ERT). An ERT system of carbon fiber smart material was developed. Field sensing characteristic was researched with the experiment. The experimental results show that the specific resistance distribution of carbon fiber smart material is highly consistent with the distribution of structural strain. High resistance zone responds to high strain area, and the specific resistance distribution of carbon fiber smart material reflects the distribution of sample strain in covering area. Monitoring by carbon fiber smart material on complicated strain status in sample field domain is realized through theoretical and experimental study.展开更多
The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse colu...The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse column on the outside of working face has been a difficult problem. Based on this, numerical simulation and imaging research were carried out in this paper. The results indicate that when a seismic source near the roadway is excited, a part of seismic wave propagates along the roadway direction, namely direct P-wave, direct S-wave and direct Love channel wave.<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">When the body waves and Love channel wave propagating to the outside</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of working face meet the interface of collapse column, the reflected Love channel wave and reflected body waves are generated.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Reflection </span><span style="font-family:Verdana;">body </span><span style="font-family:Verdana;">waves and direct waves are mixed in time domain, which is difficult to identify in seismic records, while reflected Love channel wave whose amplitude is relatively strong. The </span><span style="font-family:Verdana;">reflected </span><span style="font-family:Verdana;">Love channel wave which has a large interval from other wave trains in the time domain is easily recognizable in seismic record,</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">which</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">makes it suitable for advanced detection of collapse column. The signal-to-noise ratio of X component is higher than that of Y component and Z component. According to the seismic records, polarization filtering was carried out to enhance the effective wave, which removed the interference waves, and the signal was migrated to get the position parameters of collapse column interface, which was basically consistent with the model position.</span>展开更多
A seafloor hydrothermal field, named Deyin-1 later, near 15°S southern Mid-Atlantic Ridge（SMAR） was newly found during the 22 nd cruise carried out by the China Ocean Mineral Resources Research ＆ Development A...A seafloor hydrothermal field, named Deyin-1 later, near 15°S southern Mid-Atlantic Ridge（SMAR） was newly found during the 22 nd cruise carried out by the China Ocean Mineral Resources Research ＆ Development Association（COMRA）. Sulfide samples were collected at three stations from the hydrothermal field during the26 th cruise in 2012. In this paper, mineralogical characteristics of the sulfides were analyzed with optical microscope, X-ray diffractometer, scanning electron microscope and electron microprobe to study the crystallization sequence of minerals and the process of hydrothermal mineralization. According to the difference of the ore-forming metal elements, the sulfide samples can be divided into three types：（1） the Ferich sulfide, which contains mainly pyrite and chalcopyrite;（2） the Fe-Cu-rich sulfide consisting predominantly of pyrite, chalcopyrite and isocubanite, with lesser amount of sphalerite, marmatite and pyrrhotine; and（3） the Fe-Zn-rich sulfide dominated by pyrite, sphalerite and marmatite, with variable amounts of chalcopyrite, isocubanite, pyrrhotine, marcasite, galena and gratonite. Mineral precipitations in these sulfides are in the sequence of chalcopyrite（isocubanite and possible coarse pyrite）, fine pyrite,sphalerite（marmatite）, galena, gratonite and then the minerals out of the dissolution. Two morphologically distinct generations（Py-I and Py-II） of pyrite are identified in each of the samples; inclusions of marmatite tend to exist in the coarse pyrite crystals（Py-I）. Sphalerite in the Fe-Zn-rich sulfide is characterized by a＂chalcopyrite disease＂ phenomenon. Mineral paragenetic relationships and a wide range of chemical compositions suggest that the environment of hydrothermal mineralization was largely changing. By comparison, the Fe-rich sulfide was formed in a relatively stable environment with a high temperature, but the conditions for the formation of the Fe-Cu-rich sulfide were variable. The Fe-Zn-rich sulfide was precipitated during the hydrothermal venting at relatively low temperature.展开更多
The Rehai geothermal field in Tengchong County, Yunnan Province is a significant high-temperaturehydrothermal convective system. The geothermal reservoir is composed of granite. Various geothermometersare used to eval...The Rehai geothermal field in Tengchong County, Yunnan Province is a significant high-temperaturehydrothermal convective system. The geothermal reservoir is composed of granite. Various geothermometersare used to evaluate the reservoir temperature. The most likely temperature of the reservoir as representedby T_(Na-K-Ca) is about 230℃. The chemical and isotopic compositions of fluids before boiling within the reser-voir are estimated. The mixing and dilution of cold and warm waters are discussed. The Rehai geothermal fieldis a high-temperature (hot) water system with the subsurface boiling zone close to the surface. The reservoirpressure at different depths is calculated. And finally the water-rock equilibration is inferred.展开更多
This paper describes field modeling and thermal modeling for magnetizing fixture. As the detailed characteristics of magnetizing fixture can be. obtained, the efficient design of magnetizer which produce desired magne...This paper describes field modeling and thermal modeling for magnetizing fixture. As the detailed characteristics of magnetizing fixture can be. obtained, the efficient design of magnetizer which produce desired magnet will be possible using our modeling. For field modeling finite-element analysis is used as part of the design and analysis process for magnetizing fixture. The thermal modeling method of magnetizing fixture resistor uses multi-lumped model with equivalent thermal resistance and thermal capacitance.展开更多
The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural...The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural trap. The mechanism has three major features: (1) timing of mineralization; (2) positioning of hostformation; and (3) dependence of ore-controlling structure on properties of rocks. The 'optimum surface' is adivisional structural plane which marks obvious difference in physical, chemical and mechanical properties andis favorable for mineralization. It is also a unity of structures. lithofacies and orebodies. The structural and geochemical characteristics of the ore deposits indicate the migration trend of the ma-jor characteristic clements in the ore-controlling fault belt: elements with a small radius (Si, Fe, Mg and Al)moved towards and concentrated at the center of the belt while large-radius ones (Ca, K and Na) were remotefrom the center.展开更多
The southern part of the Kyushu-Palau Ridge(KPR)is located at the conjunction of the West Philippine Basin,the Parece Vela Basin,the Palau Basin,and the Caroline Basin.This area has extremely complex structures and is...The southern part of the Kyushu-Palau Ridge(KPR)is located at the conjunction of the West Philippine Basin,the Parece Vela Basin,the Palau Basin,and the Caroline Basin.This area has extremely complex structures and is critical for the research on the tectonic evolution of marginal seas in the Western Pacific Ocean.However,only few studies have been completed on the southern part,and the geophysical fields and deep structures in this part are not well understood.Given this,this study finely depicts the characteristics of the gravity and magnetic anomalies and extracts information on deep structures in the southern part of the KPR based on the gravity and magnetic data obtained from the 11th expedition of the deep-sea geological survey of the Western Pacific Ocean conducted by the Guangzhou Marine Geological Survey,China Geological Survey using the R/V Haiyangdizhi 6.Furthermore,with the data collected on the water depth,sediment thickness,and multichannel seismic transects as constraints,a 3D density model and Moho depths of the study area were obtained using 3D density inversion.The results are as follows.(1)The gravity and magnetic anomalies in the study area show distinct zoning and segmentation.In detail,the gravity and magnetic anomalies to the south of 11°N of the KPR transition from high-amplitude continuous linear positive anomalies into low-amplitude intermittent linear positive anomalies.In contrast,the gravity and magnetic anomalies to the north of 11°N of the KPR are discontinuous and show alternating positive and negative anomalies.These anomalies can be divided into four sections,of which the separation points correspond well to the locations of deep faults,thus,revealing different field-source attributes and tectonic genesis of the KPR.(2)The Moho depth in the basins in the study area is 6-12 km.The Moho depth in the southern part of KPR show segmentation.Specifically,the depth is 10‒12 km to the north of 11°N,12‒14 km from 9.5°N to 11°N,14-16 km from 8.5°N to 9.5°N,and 16‒25 km in the Palau Islands.(3)The KPR is a remnant intra-oceanic arc with the oceanic-crust basement.which shows noticeably discontinuous from north to south in geological structure and is intersected by NEE-trending lithospheric-scale deep faults.With large and deep faults F3 and F1(the Mindanao fault)as boundaries overall,the southern part of the KPR can be divided into three zones.In detail,the portion to the south of 8.5°N(F3)is a tectonically active zone,the KPR portion between 8.5°N and 11°N is a tectonically active transition zone,and the portion to the north of 11°N is a tectonically inactive zone.(4)The oceanic crust in the KPR is slightly thicker than that in the basins on both sides of the ridge,and it is inferred that the KPR formed from the thickening of the oceanic crust induced by the upwelling of deep magma in the process of rifting of remnant arcs during the Middle Oligocene.In addition,it is inferred that the thick oceanic crust under the Palau Islands is related to the constant upwelling of deep magma induced by the continuous northwestward subduction of the Caroline Plate toward the Palau Trench since the Late Oligocene.This study provides a scientific basis for systematically understanding the crustal attributes,deep structures,and evolution of the KPR.展开更多
By the utilization of monthly precipitation data from all stations in the Northern Hemisphere annexed to the 'World Survey of climatology, Vol. 1-15', the distributions of the maximum precipitation months (MPM...By the utilization of monthly precipitation data from all stations in the Northern Hemisphere annexed to the 'World Survey of climatology, Vol. 1-15', the distributions of the maximum precipitation months (MPM), the annual relative precipitation (ARP) and the monthly relative precipitation (percent of annual) in January and July are respectively mapped. Moreover the distributions of intermonthly relative precipitation variabilities from January to December are plotted as well. From these figures, the precipitation in the Northern Hemisphere may be classified into three types(continental, oceanic and transitional types) and 17 regions. The precipitation regime may also be divided into two patterns, the global and regional patterns. The global pattern consists of planetary front system and ITCZ and its inter-monthly variation shows the north-and-south shift of the rain belt; the regional pattern consists of the sea-land monsoon and plateau monsoon regime, in which the inter-monthly variation of rain belt shows a east-and-wcst shift.展开更多
The geothermal field is mainly controlled by the regional tectonic framework characterized by alternationsof uplifted and depressed basement. and exhibits a similar zoned distribution of temperatures. In the uplifteda...The geothermal field is mainly controlled by the regional tectonic framework characterized by alternationsof uplifted and depressed basement. and exhibits a similar zoned distribution of temperatures. In the upliftedarea the geothermal gradient （G） and terrestrial heat flow value（q） of the Cenozoic sedimentary cover are rela-tively high, with G=3.5-5.0℃/100m and q=63-84mW/m;; whereas in the depressions they are rela-tively low, with G=2.7-3.5℃/100m and q=46-59mW/m;. In the whole region, G=3.58℃/100m and q=61.5±13.4nW/m;, indicating a comparatively high geothermal background and the presence of localgeothermal anomalies. A comparison of the results of mathematical simulation of the geothermal field with themeasured values shows a good agrecment between them. The geothermal difference between various tectonicunits is caused chiefly by the lateral and vertical variation of thermal properties of shallow crustal rocks. Thisphenomenon can be regarded as the result of redistribution of relatively uniform heat flows from the deep crustin the surficial part of the crust in the process of their upward conduction.展开更多
The paper analyzes the variation characteristics of energy fields of seismicity 2.1≤M L ≤4.5 in Jiangsu and its neighboring areas during the period between January 1970 and December 2007.It also analyzes the variati...The paper analyzes the variation characteristics of energy fields of seismicity 2.1≤M L ≤4.5 in Jiangsu and its neighboring areas during the period between January 1970 and December 2007.It also analyzes the variations of time "weight" coefficients of the major typical energy fields,using random function theory with seismic energy fields as a space-time random function field based on Empirical Orthogonal Function (EOF) expansion methods.The results show that the expansion accuracy of the first seven typical fields is 0.9244.The strength of seismic energy varies remarkably in different tectonic blocks in the study area.High value areas are in middle and southern Jiangsu,and the south Yellow Sea.The distribution of the typical fields also shows that it is an area that affects most significantly the seismic energy fields of the study region.The time "weight" coefficients of the first six typical fields vary with time,and the amplitude of the variations has strong temporal correlations with moderate-strong earthquakes in the region.展开更多
基金financially supported by the Chang Jiang Scholar and Innovation Team Development Plan of China (IRT_15R29)the Basic Research Innovation Group Project of Gansu Province, China (21JR7RA347)the Natural Science Foundation of Gansu Province, China (20JR10RA231)。
文摘Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.
基金supported by the National Natural Science Foundation of China(No.32002442)the National Key R&D Program(No.2019YFD0902101).
文摘On the basis of computational fluid dynamics,the flow field characteristics of multi-trophic artificial reefs,including the flow field distribution features of a single reef under three different velocities and the effect of spacing between reefs on flow scale and the flow state,were analyzed.Results indicate upwelling,slow flow,and eddy around a single reef.Maximum velocity,height,and volume of upwelling in front of a single reef were positively correlated with inflow velocity.The length and volume of slow flow increased with the increase in inflow velocity.Eddies were present both inside and backward,and vorticity was positively correlated with inflow velocity.Space between reefs had a minor influence on the maximum velocity and height of upwelling.With the increase in space from 0.5 L to 1.5 L(L is the reef lehgth),the length of slow flow in the front and back of the combined reefs increased slightly.When the space was 2.0 L,the length of the slow flow decreased.In four different spaces,eddies were present inside and at the back of each reef.The maximum vorticity was negatively correlated with space from 0.5 L to 1.5 L,but under 2.0 L space,the maximum vorticity was close to the vorticity of a single reef under the same inflow velocity.
基金The National Natural Science Foundation of China under contract Nos 50979008 and 50909009Program for Hunan Province Key Laboratory of WaterSediment Sciences & Flood Hazard Prevention and Open Research Fund Program of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University No.2008490911
文摘In this study, characteristics of flow field and wave propagation near submerged breakwater on a sloping bed are investigated with numerical model. The governing equations of the vertical two-dimensional model are Reynolds Averaged Navier Stokes equations. The Reynolds stress terms are closed by a nonlinear k - ε turbulence transportation model. The free surface is traced through the PILC-VOF method. The proposed numerical model is verified with experimental results. The numerical result shows that the wave profile may become more asymmetrical when wave propagates over breakwater. When wave crest propagates over breakwater, the anticlockwise vortex may generate. On the contrary, when wave hollow propagates over breakwater, the clockwise vortex may generate. Meanwhile, the influenced zone of vortex created by wave crest is larger than that created by wave hollow. All the maximum values of the turbulent kinetic energy, turbulent dissipation and eddy viscosity occur on the top of breakwater. Both the turbulent dissipation and eddy viscosity increase as the turbulent kinetic energy increases. Wave energy may rapidly decrease near the breakwater because turbulent dissipation increases and energy in lower harmonics is transferred into higher harmonics.
基金Supported by the Fundamental Research Funds for the Central Universities(2012QNA4018)the National Natural Science foundation of China(21206144)the Program for Zhejiang Leading Team of S&T Innovation(2011R50005)
文摘A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Rushton turbine. The power consumption and flow field characteristics of the coaxial mixer in laminar and transitional flow are simulated numerically, and then the distribution of velocity field, shear rate and mass flow rate are analyzed. The simulation results indicate that the outer frame has little effect on the power consumption of the double inner impeller whether in laminar or transitional flow, whereas the inner combined impeller has a great effect on the power consumption of the outer frame. Compared with the single rotation mode, the power consumption of the outer frame will decrease in co-rotation mode and increase in counter-rotation mode. The velocity, shear rate and mass flow rate are relatively high near the inner impeller in all operating modes, and only under double-shaft agitation will the mixing performance near the free surface be improved.In addition, these distributions in the co-rotation and counter-rotation modes show little difference, but the co-rotation mode is recommended for the advantage of low power consumption.
文摘The overburden failure causes the changes of the constant electric field, and the resistivity is the main parameter in these changes. The experimental simulation about tbe response relation between the overburden failure and its electrical parameter changes is made by building the similar material physics model of mining. The experiment results are used to analyze and test the in-situ detection. The research indicates that the resistivity changes with the electric characteristic of the rock in cracked zone and caving zone caused by overburden failure, the response characteristics of resistivity vary with the failure degrees at different overburden failure zone and that they are corresponding. The resistivity method used in monitoring the overburden failure can determine the height and the affecting scopes of the cracked zone and caving zone. This can provide reliable techaological guarantee for mining design and safe production.
基金supported by National Natural Science Foundation of China (Grant No. 50474035)
文摘The turbo air classifier is widely used powder classification equipment in a variety of fields. The flow field characteristics of the turbo air classifier are important basis for the improvement of the turbo air classifier＇s structural design. The flow field characteristics of the rotor cage in turbo air classifiers were investigated trader different operating conditions by laser Doppler velocimeter（LDV）, and a measure diminishing the axial velocity is proposed. The investigation results show that the tangential velocity of the air flow inside the rotor cage is different from the rotary speed of the rotor cage on the same measurement point due to the influences of both the negative pressure at the exit and the rotation of the rotor cage. The tangential velocity of the air flow likewise decreases as the radius decreases in the case of the rotor cage＇s low rotary speed. In contrast, the tangential velocity of the air flow increases as the radius decreases in the case of the rotor cage＇s high rotary speed. Meanwhile, the vortex inside the rotor cage is found to occur near the pressure side of the blade when the rotor cage＇s rotary speed is less than the tangential velocity of air flow. On the contrary, the vortex is found to occur near the blade suction side once the rotor cage＇s rotary speed is higher than the tangential velocity of air flow. Inside the rotor cage, the axial velocity could not be disregarded and is largely determined by the distances between the measurement point and the exit.
基金the Science and Technology Innovation and Entrepreneurship Fund of China Coal Technology Engineering Group(2019-TD-QN038,2019-TDQN017)Enterprise Independent Innovation Guidance Project(2018ZDXM05,2019YBXM30).
文摘The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-εturbulence model,and compared with the results of dedicated rock breaking drilling experiments.The numerical results show that the nozzle velocity and dynamic pressure of the nozzle decrease with an increase in the jet distance,and the axial velocity of the nozzle decays regularly with an increase in the dimensionless jet distance.Moreover,the axial velocity related to the nozzle with inclination angle 20°and 30°can produce a higher hole depth,while the radial velocity of the nozzle with 60°inclination can enlarge the hole diameter.The outcomes of the CFD simulations are consistent with the actual dynamic rock breaking and pore forming process,which lends credence to the present results and indicates that they could be used as a reference for the future optimization of systems based on the multi-hole combined external rotary bit technology.
基金National Natural Science Foundation of China(50674003)National Basic Research Program(973)
文摘The change rules of displacement field characteristics of coal seam and tunners surrounding rock were obtained by means of numerical simulation-FLAC^3D and site observation, and according to engineering geology and exploitation technology of 1151 （3） fully mechanized top coal caving （FMTC） face in Xieqiao colliery. The research＇s results show that the top coal displacement on the top of FMTC face is apparently larger than those of the middle and the bottom, the top coal begins to move in the front of the face＇s wall, and the sub-level top coal-rock moves ahead of the low-level top coal-rock, the vertical displacement of top coal-rock increases gradually as the decreasing of distance to face Top coal and overlying strata in vertical direction are always in compressed state in the front of face, then the top coal begins to separate from the overlying strata at the upside of face. The support loading at face is mainly the deformation pressure due to top coal and main roof＇s movement, and it is not suitable for the FMTC face with traditional support design. Surrounding rock movement of the face is of near-field effect, the surrounding rock deformation is acute greatly near to the face, the ideas of supporting design for the tailentry and headentry should be changed from loading control to deformation control.
基金National Natural Science Foundation of China(No.51867013)。
文摘The installed porcelain insulators on existing railway lines in China are prone to“snow flash”in winter.In order to prevent the occurrence of“snow flash”and improve the reliability of the insulators,a composite-porcelain insulator is designed.A multi-physics coupling simulation model is built based on numerical simulation methods of the electromagnetic field theory and computational fluid dynamics.Taking average electric field intensity on the surface of the insulator as the characteristic parameter of the electric field distortion degree and the snow crystal collision coefficient and distribution coefficient as the characteristic parameter of snow crystal deposition,the characteristics of snow crystal deposition under different wind speeds and wind direction angles and the electric field characteristics under two snow cover types are analyzed.The simulation results show that the average electric field intensity of composite-porcelain insulators is 10.4%and 13.8%,respectively,lower than that of porcelain insulators in vertical and horizontal wind snow covers,which can effectively reduce the degree of electric field distortion.The collision coefficient of snow crystals on the surface of the composite-porcelain insulator sheds is 16.0%higher than that of the porcelain insulator,and the collision coefficient of the trunk and the fittings are lower 20.2%and 11.9%than that of the porcelain insulator.There is almost no change in the distribution coefficient of the insulator sheds.
基金Funded by the National High-tech Research and Development Program of China(863 Program)(No.2013AA031306)
文摘In order to research the field sensing characteristic of the carbon fiber smart material, the Tikhonov regularization principle and the modified Newton-Raphson(MNR) algorithm were adopted to solve the inverse problem of the electrical resistance tomography(ERT). An ERT system of carbon fiber smart material was developed. Field sensing characteristic was researched with the experiment. The experimental results show that the specific resistance distribution of carbon fiber smart material is highly consistent with the distribution of structural strain. High resistance zone responds to high strain area, and the specific resistance distribution of carbon fiber smart material reflects the distribution of sample strain in covering area. Monitoring by carbon fiber smart material on complicated strain status in sample field domain is realized through theoretical and experimental study.
文摘The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse column on the outside of working face has been a difficult problem. Based on this, numerical simulation and imaging research were carried out in this paper. The results indicate that when a seismic source near the roadway is excited, a part of seismic wave propagates along the roadway direction, namely direct P-wave, direct S-wave and direct Love channel wave.<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">When the body waves and Love channel wave propagating to the outside</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of working face meet the interface of collapse column, the reflected Love channel wave and reflected body waves are generated.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Reflection </span><span style="font-family:Verdana;">body </span><span style="font-family:Verdana;">waves and direct waves are mixed in time domain, which is difficult to identify in seismic records, while reflected Love channel wave whose amplitude is relatively strong. The </span><span style="font-family:Verdana;">reflected </span><span style="font-family:Verdana;">Love channel wave which has a large interval from other wave trains in the time domain is easily recognizable in seismic record,</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">which</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">makes it suitable for advanced detection of collapse column. The signal-to-noise ratio of X component is higher than that of Y component and Z component. According to the seismic records, polarization filtering was carried out to enhance the effective wave, which removed the interference waves, and the signal was migrated to get the position parameters of collapse column interface, which was basically consistent with the model position.</span>
基金The National Basic Research Program(973 Program)of China under contract No.2013CB429702the National Oceanic Major Project of 12th Five Year under contract No.DY125-11-R-05
文摘A seafloor hydrothermal field, named Deyin-1 later, near 15°S southern Mid-Atlantic Ridge（SMAR） was newly found during the 22 nd cruise carried out by the China Ocean Mineral Resources Research ＆ Development Association（COMRA）. Sulfide samples were collected at three stations from the hydrothermal field during the26 th cruise in 2012. In this paper, mineralogical characteristics of the sulfides were analyzed with optical microscope, X-ray diffractometer, scanning electron microscope and electron microprobe to study the crystallization sequence of minerals and the process of hydrothermal mineralization. According to the difference of the ore-forming metal elements, the sulfide samples can be divided into three types：（1） the Ferich sulfide, which contains mainly pyrite and chalcopyrite;（2） the Fe-Cu-rich sulfide consisting predominantly of pyrite, chalcopyrite and isocubanite, with lesser amount of sphalerite, marmatite and pyrrhotine; and（3） the Fe-Zn-rich sulfide dominated by pyrite, sphalerite and marmatite, with variable amounts of chalcopyrite, isocubanite, pyrrhotine, marcasite, galena and gratonite. Mineral precipitations in these sulfides are in the sequence of chalcopyrite（isocubanite and possible coarse pyrite）, fine pyrite,sphalerite（marmatite）, galena, gratonite and then the minerals out of the dissolution. Two morphologically distinct generations（Py-I and Py-II） of pyrite are identified in each of the samples; inclusions of marmatite tend to exist in the coarse pyrite crystals（Py-I）. Sphalerite in the Fe-Zn-rich sulfide is characterized by a＂chalcopyrite disease＂ phenomenon. Mineral paragenetic relationships and a wide range of chemical compositions suggest that the environment of hydrothermal mineralization was largely changing. By comparison, the Fe-rich sulfide was formed in a relatively stable environment with a high temperature, but the conditions for the formation of the Fe-Cu-rich sulfide were variable. The Fe-Zn-rich sulfide was precipitated during the hydrothermal venting at relatively low temperature.
基金This paper is one or the results of Project D14021 sponsored by the National Natural Science Foundation.
文摘The Rehai geothermal field in Tengchong County, Yunnan Province is a significant high-temperaturehydrothermal convective system. The geothermal reservoir is composed of granite. Various geothermometersare used to evaluate the reservoir temperature. The most likely temperature of the reservoir as representedby T_(Na-K-Ca) is about 230℃. The chemical and isotopic compositions of fluids before boiling within the reser-voir are estimated. The mixing and dilution of cold and warm waters are discussed. The Rehai geothermal fieldis a high-temperature (hot) water system with the subsurface boiling zone close to the surface. The reservoirpressure at different depths is calculated. And finally the water-rock equilibration is inferred.
文摘This paper describes field modeling and thermal modeling for magnetizing fixture. As the detailed characteristics of magnetizing fixture can be. obtained, the efficient design of magnetizer which produce desired magnet will be possible using our modeling. For field modeling finite-element analysis is used as part of the design and analysis process for magnetizing fixture. The thermal modeling method of magnetizing fixture resistor uses multi-lumped model with equivalent thermal resistance and thermal capacitance.
文摘The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural trap. The mechanism has three major features: (1) timing of mineralization; (2) positioning of hostformation; and (3) dependence of ore-controlling structure on properties of rocks. The 'optimum surface' is adivisional structural plane which marks obvious difference in physical, chemical and mechanical properties andis favorable for mineralization. It is also a unity of structures. lithofacies and orebodies. The structural and geochemical characteristics of the ore deposits indicate the migration trend of the ma-jor characteristic clements in the ore-controlling fault belt: elements with a small radius (Si, Fe, Mg and Al)moved towards and concentrated at the center of the belt while large-radius ones (Ca, K and Na) were remotefrom the center.
基金This work was supported by the project of China Geological Survey(DD20191002)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0208)the National Natural Science Foundation of China(41606080,41576068)。
文摘The southern part of the Kyushu-Palau Ridge(KPR)is located at the conjunction of the West Philippine Basin,the Parece Vela Basin,the Palau Basin,and the Caroline Basin.This area has extremely complex structures and is critical for the research on the tectonic evolution of marginal seas in the Western Pacific Ocean.However,only few studies have been completed on the southern part,and the geophysical fields and deep structures in this part are not well understood.Given this,this study finely depicts the characteristics of the gravity and magnetic anomalies and extracts information on deep structures in the southern part of the KPR based on the gravity and magnetic data obtained from the 11th expedition of the deep-sea geological survey of the Western Pacific Ocean conducted by the Guangzhou Marine Geological Survey,China Geological Survey using the R/V Haiyangdizhi 6.Furthermore,with the data collected on the water depth,sediment thickness,and multichannel seismic transects as constraints,a 3D density model and Moho depths of the study area were obtained using 3D density inversion.The results are as follows.(1)The gravity and magnetic anomalies in the study area show distinct zoning and segmentation.In detail,the gravity and magnetic anomalies to the south of 11°N of the KPR transition from high-amplitude continuous linear positive anomalies into low-amplitude intermittent linear positive anomalies.In contrast,the gravity and magnetic anomalies to the north of 11°N of the KPR are discontinuous and show alternating positive and negative anomalies.These anomalies can be divided into four sections,of which the separation points correspond well to the locations of deep faults,thus,revealing different field-source attributes and tectonic genesis of the KPR.(2)The Moho depth in the basins in the study area is 6-12 km.The Moho depth in the southern part of KPR show segmentation.Specifically,the depth is 10‒12 km to the north of 11°N,12‒14 km from 9.5°N to 11°N,14-16 km from 8.5°N to 9.5°N,and 16‒25 km in the Palau Islands.(3)The KPR is a remnant intra-oceanic arc with the oceanic-crust basement.which shows noticeably discontinuous from north to south in geological structure and is intersected by NEE-trending lithospheric-scale deep faults.With large and deep faults F3 and F1(the Mindanao fault)as boundaries overall,the southern part of the KPR can be divided into three zones.In detail,the portion to the south of 8.5°N(F3)is a tectonically active zone,the KPR portion between 8.5°N and 11°N is a tectonically active transition zone,and the portion to the north of 11°N is a tectonically inactive zone.(4)The oceanic crust in the KPR is slightly thicker than that in the basins on both sides of the ridge,and it is inferred that the KPR formed from the thickening of the oceanic crust induced by the upwelling of deep magma in the process of rifting of remnant arcs during the Middle Oligocene.In addition,it is inferred that the thick oceanic crust under the Palau Islands is related to the constant upwelling of deep magma induced by the continuous northwestward subduction of the Caroline Plate toward the Palau Trench since the Late Oligocene.This study provides a scientific basis for systematically understanding the crustal attributes,deep structures,and evolution of the KPR.
文摘By the utilization of monthly precipitation data from all stations in the Northern Hemisphere annexed to the 'World Survey of climatology, Vol. 1-15', the distributions of the maximum precipitation months (MPM), the annual relative precipitation (ARP) and the monthly relative precipitation (percent of annual) in January and July are respectively mapped. Moreover the distributions of intermonthly relative precipitation variabilities from January to December are plotted as well. From these figures, the precipitation in the Northern Hemisphere may be classified into three types(continental, oceanic and transitional types) and 17 regions. The precipitation regime may also be divided into two patterns, the global and regional patterns. The global pattern consists of planetary front system and ITCZ and its inter-monthly variation shows the north-and-south shift of the rain belt; the regional pattern consists of the sea-land monsoon and plateau monsoon regime, in which the inter-monthly variation of rain belt shows a east-and-wcst shift.
文摘The geothermal field is mainly controlled by the regional tectonic framework characterized by alternationsof uplifted and depressed basement. and exhibits a similar zoned distribution of temperatures. In the upliftedarea the geothermal gradient （G） and terrestrial heat flow value（q） of the Cenozoic sedimentary cover are rela-tively high, with G=3.5-5.0℃/100m and q=63-84mW/m;; whereas in the depressions they are rela-tively low, with G=2.7-3.5℃/100m and q=46-59mW/m;. In the whole region, G=3.58℃/100m and q=61.5±13.4nW/m;, indicating a comparatively high geothermal background and the presence of localgeothermal anomalies. A comparison of the results of mathematical simulation of the geothermal field with themeasured values shows a good agrecment between them. The geothermal difference between various tectonicunits is caused chiefly by the lateral and vertical variation of thermal properties of shallow crustal rocks. Thisphenomenon can be regarded as the result of redistribution of relatively uniform heat flows from the deep crustin the surficial part of the crust in the process of their upward conduction.
基金the Key Projects in the National S&T Pillar Program during the Eleventh "Five-year Plan" Period(2006BAC01B03-03-01),China Earthquake AdministrationYouth Fund of Earthquake Administration of Jiangsu Province(2009),China
文摘The paper analyzes the variation characteristics of energy fields of seismicity 2.1≤M L ≤4.5 in Jiangsu and its neighboring areas during the period between January 1970 and December 2007.It also analyzes the variations of time "weight" coefficients of the major typical energy fields,using random function theory with seismic energy fields as a space-time random function field based on Empirical Orthogonal Function (EOF) expansion methods.The results show that the expansion accuracy of the first seven typical fields is 0.9244.The strength of seismic energy varies remarkably in different tectonic blocks in the study area.High value areas are in middle and southern Jiangsu,and the south Yellow Sea.The distribution of the typical fields also shows that it is an area that affects most significantly the seismic energy fields of the study region.The time "weight" coefficients of the first six typical fields vary with time,and the amplitude of the variations has strong temporal correlations with moderate-strong earthquakes in the region.
