The melting process of a phase change material(PCM) inside a capsule can be promising in the thermal management of spacecraft. Such spacecraft operate under various gravity conditions, but previous studies have mostly...The melting process of a phase change material(PCM) inside a capsule can be promising in the thermal management of spacecraft. Such spacecraft operate under various gravity conditions, but previous studies have mostly considered the influence of gravity conditions on the constrained melting process of a PCM and not on its unconstrained melting process. In this study, a numerical model was constructed to comprehensively analyze the constrained and unconstrained melting processes of a PCM inside a spherical capsule under low-gravity conditions. After validation, the model was then applied to investigating the effects of low-gravity conditions on the evolution of velocity, temperature, melt layer thickness, heat transfer, liquid fraction, and total melting time. For the unconstrained melting process, low-gravity conditions weaken buoyancy-driven natural convection and slow down the solid PCM downward trend, thereby limiting the melting rate. In addition, the melt layer thickness does not increase linearly with decreasing gravity. Specifically, the increase in melt layer thickness is smaller by about 1.06 mm when the gravity drops from 0.4g to 0.2g compared to when it drops from 0.2g to 0.1g. The local heat flux in the contact melting area gradually decreases with the reduction of gravity during the unconstrained melting process. During the constrained melting process, notable oscillations in the local heat flux were observed. Decreasing the gravity from g to 0g increased the total melting times of the constrained and unconstrained melting processes by 417% and 621%, respectively.展开更多
A novel method for noise removal from the rotating accelerometer gravity gradiometer(MAGG)is presented.It introduces a head-to-tail data expansion technique based on the zero-phase filtering principle.A scheme for det...A novel method for noise removal from the rotating accelerometer gravity gradiometer(MAGG)is presented.It introduces a head-to-tail data expansion technique based on the zero-phase filtering principle.A scheme for determining band-pass filter parameters based on signal-to-noise ratio gain,smoothness index,and cross-correlation coefficient is designed using the Chebyshev optimal consistent approximation theory.Additionally,a wavelet denoising evaluation function is constructed,with the dmey wavelet basis function identified as most effective for processing gravity gradient data.The results of hard-in-the-loop simulation and prototype experiments show that the proposed processing method has shown a 14%improvement in the measurement variance of gravity gradient signals,and the measurement accuracy has reached within 4E,compared to other commonly used methods,which verifies that the proposed method effectively removes noise from the gradient signals,improved gravity gradiometry accuracy,and has certain technical insights for high-precision airborne gravity gradiometry.展开更多
A novel process utilizing vertical wells to enhance heavy oil recovery during steam assisted gravity drainage has been developed. In the vertical well steam assisted gravity drainage (VWSAGD) process shown in Figure 1...A novel process utilizing vertical wells to enhance heavy oil recovery during steam assisted gravity drainage has been developed. In the vertical well steam assisted gravity drainage (VWSAGD) process shown in Figure 1, the vertical well includes two production strings which are separated by three packers (one dual and two single packers): the short injection string (SIS) is attached to the bottom of the annulus and completed in the top quarter of the perforated formation, while the long production string (LPS) is attached to the bottom of the production tubing and completed in the bottom quarter of the perforated formation. The new process (VWSAGD) requires an initial start-up period (warm-up stage) where the steam is injected into both of the injection strings and production string for a specified period of time of about 14-30 days;then both strings are closed to injection for a specified time period of approximately 7 - 10 days (soaking period). After the initial warm-up and the soaking period, the long production string is opened for production, and the short injection string is opened to continuous steam injection for the rest of the specified simulation time. A commercial simulator (CMG-STAR Simulator) was used to study the performance of the new VWSAGD process. A sensitivity analysis was performed for the grid density, soaking time, steam quality, bottom hole producing pressure, steam injection rate, reservoir thickness, reservoir area, and horizontal to vertical permeability anisotropy. The results of this study have shown that the new VWSAGD process is more preferable for reservoir conditions such as high horizontal to vertical permeability ratio and thick reservoir oil zones.展开更多
A numerical simulation study using the CMG-STAR Simulator was performed to compare the performance of the newly developed process (VWSAGD) utilizing vertical wells to enhance heavy oil recovery during steam assisted g...A numerical simulation study using the CMG-STAR Simulator was performed to compare the performance of the newly developed process (VWSAGD) utilizing vertical wells to enhance heavy oil recovery during steam assisted gravity drainage against the conventional steam assisted gravity drainage process which utilized horizontal wells (HWSAGD) under the same operating conditions. Two identical reservoir models were simulated for the two processes using 3-Dimensional, black heavy oil model (14° API). Each reservoir type consists of 49 × 49 × 20 grid blocks on a 5-acre model, which incorporated a typical heavy oil reservoir rock and fluid properties taken from the SPE case study, stspe001.dat (CMG 2015 release). A sensitivity analysis for both processes was performed for the grid density, soaking time, steam quality, bottom hole producing pressure, steam injection rate, reservoir thickness, reservoir area, and horizontal to vertical permeability anisotropy. More preferable reservoir conditions are those such as high horizontal to vertical permeability ratio, thick reservoir oil zones, as well as improved reservoir recovery for the VWSAGD process. Under unfavorable conditions such as thin reservoir oil zones, an improved reservoir recovery response was limited for the VWSAGD process and could be uneconomical in real field cases. Finally, the simulation results from this study include cumulative recoveries, Steam oil ratios, produced water-oil ratios, pressure and temperature distributions, and production rates. In addition, the results from this study have shown that the new VWSAGD process is more favorable than the conventional HWSAGD process.展开更多
Copper and cobalt were recovered from SICOMINES mining waste rock in the Democratic Republic of Congo.The process mineralogy of the samples was analyzed using scanning electron microscopy and energy dispersive spectro...Copper and cobalt were recovered from SICOMINES mining waste rock in the Democratic Republic of Congo.The process mineralogy of the samples was analyzed using scanning electron microscopy and energy dispersive spectroscopy.The results showed that copper minerals exhibited various forms and uneven particle sizes,while cobalt existed in the form of highly dispersed asbolane,and large amounts of easily slimed gangue minerals were filled in the samples,making it difficult to separate copper and cobalt minerals.The particle size range plays a decisive role in selecting the separation method for the copper−cobalt ore.Gravity separation was suitable for particles ranging from 43 to 246μm,while flotation was more effective for particles below 43μm.After ore grinding and particle size classification,applying a combined gravity separation(shaking table)−flotation method yielded concentrated minerals with a copper recovery of 72.83%and a cobalt recovery of 31.13%.展开更多
Coal gasification fine slag(CGFS)is a solid waste produced in the process of coal gasification.The separation of residue carbon in CGFS is essential for its resource utilization.In this study,the basic physical proper...Coal gasification fine slag(CGFS)is a solid waste produced in the process of coal gasification.The separation of residue carbon in CGFS is essential for its resource utilization.In this study,the basic physical properties of CGFS were analyzed and the effect of physical separation experiments were carried out.The gravity separation results indicated that the coarser particle size fraction achieved a good separation effect.The High-carbon product has a yield of 12.53% with an ash content of 16.84%,and the High-ash product has a yield of 17.85%with an ash content of 98.15% were obtained.Theoretical calculations indicated that the apparent density difference between residue carbon and ash minerals in the water phase environment was the basis for achieving separation.The Rich-ash product was further separated by magnetic separation,and both magnetic field characteristics,water elutriation frequency and grinding time had impacts on the magnetic separation effect.Compared to gravity separation alone,the combined gravity-magnetic separation further enhanced the separation effect of residue carbon and ash minerals.The ash content of the Rich-ash product decreased from 80.56% to 69.52% due to the removal of high-ash Fe oxides,and the yield of combined separation tailings increased from 17.85% to 41.75%.The characterization results obtained through SEM-EDS,VSM,XRD and XRF analysis demonstrated significant differences in saturation magnetization,mineral composition and peak intensity among magnetic separation products,confirming that the feasibility of magnetic separation.The research findings contribute to a better understanding of the separation mechanism and provide a new separation process for efficiently enriching residue carbon from CGFS,also facilitate the step utilization of separation products.展开更多
We developed the China Regional Gravity Information System（RGIS） using mixed language programming in Visual Basic,Visual C＋＋,and FORTRAN.The software is based on the MapInfo platform with OLE technology.With this ...We developed the China Regional Gravity Information System（RGIS） using mixed language programming in Visual Basic,Visual C＋＋,and FORTRAN.The software is based on the MapInfo platform with OLE technology.With this system,we achieve visual data management for the database with spatial geography,geology data and gravity data as well as graphical data editing and data table operations over the whole of China.We are able to perform normalized gravity reduction,gravity and magnetic field transforms,gravity anomaly inversion and interpretation,thematic mapping and so on.展开更多
Absolute and relative gravity data during 1998 to 2008 were used to study gravity field and temporal variation in the North-South seismic-belt region, and their correlation with seismic activities before and after Wen...Absolute and relative gravity data during 1998 to 2008 were used to study gravity field and temporal variation in the North-South seismic-belt region, and their correlation with seismic activities before and after Wenchuan Ms8.0 earthquake. The temporal variation of gravity field shows that the portentous information of the gravity field reflects the development and occurrence of earthquake more clearly. The variations of gravity field are inhomogeneous in the space-time distribution, and are associated with the development and occurrence of the Wenchuan Ms8.0 earthquake, also closely connected with active fault tectonics.展开更多
In this work,we report an innovative route for the synthesis of rare-earth doped calcium molybdate(CaMoO4)nanophosphors by using high gravity rotating packed bed(RPB)technology and paraffin liquid as the solvent.The s...In this work,we report an innovative route for the synthesis of rare-earth doped calcium molybdate(CaMoO4)nanophosphors by using high gravity rotating packed bed(RPB)technology and paraffin liquid as the solvent.The significant intensified mass transfer and micromixing of reactants in the RPB reactor are benefiting for homogeneous doping of rare-earth ions in the host materials,leading to nanophosphors with high quantum efficiency.The use of liquid paraffin as the solvent eliminates the safety risks associated with volatile organic compounds,increasing the potential for clean production of nanophosphors.Under excitation of deep ultraviolet(DUV)light,the CaMoO4:Na+,Eu3+nanophosphors exhibit red emission at peak wavelength of 615 nm and quantum yield of up to 35.01%.The CaMoO4:Na+,Tb3+nanophosphors exhibit green emission at peak wavelength of543 nm with quantum yield of up to 30.66%.The morphologies of the nanophosphors are tunable from nanofibers through nanorods to nanodots and the possible mechanism of controlling the formation of different nanostructures is proposed on the basis of experimental results and theoretical analysis of mesoscience.These nanophosphors are highly dispersible in organic solvents and utilized for fabricating fabrication of flexible,freestanding luminescent films based on silicone resin.We also demonstrate the red LEDs consisting of the hybrid films of CaMoO4:Na+,Eu3+nanoparticles as color-converting phosphors and DUV LEDs as illuminators,offering strong potential for future nanophosphors-basedsolid-state lighting systems.展开更多
The comprehensive evaluation of Tahe medium gravity crude has demonstrated that this type of crude belongs to a intermediate base sour crude, featuring high vanadium content (103ppm), high carbon residue content, low ...The comprehensive evaluation of Tahe medium gravity crude has demonstrated that this type of crude belongs to a intermediate base sour crude, featuring high vanadium content (103ppm), high carbon residue content, low pour point, and low acid value. Based on the crude processing conditions at SINOPEC Luoyang Petrochemical Branch Company, a proposal on the appropriate process flow scheme for processing Tahe crude oil has been raised with the main ideas presented as follows. The IBP-175 fraction is not an ideal feedstock for catalytic reforming; the 75-250 fraction is a qualified feedstock for zeolite de-waxing; the 140-230 fraction can be used to manufacture the No. 3 jet fuel through appropriate distillation range adjustment and product refining; the 175-350 fraction can be directly used to manufacture No.-10 diesel through proper refining; the atmospheric resid boiling over 350 is not suited to be used as the RFCC feedstock; the 350-520 vacuum distillate oil can be used as the FCC feedstock; and the vacuum residuum boiling over 520 is a good feedstock for manufacture of asphalt.展开更多
The gravity gradient is a secondary derivative of gravity potential,containing more high-frequency information of Earth’s gravity field.Gravity gradient observation data require deducting its prior and intrinsic part...The gravity gradient is a secondary derivative of gravity potential,containing more high-frequency information of Earth’s gravity field.Gravity gradient observation data require deducting its prior and intrinsic parts to obtain more variational information.A model generated from a topographic surface database is more appropriate to represent gradiometric effects derived from near-surface mass,as other kinds of data can hardly reach the spatial resolution requirement.The rectangle prism method,namely an analytic integration of Newtonian potential integrals,is a reliable and commonly used approach to modeling gravity gradient,whereas its computing efficiency is extremely low.A modified rectangle prism method and a graphical processing unit(GPU)parallel algorithm were proposed to speed up the modeling process.The modified method avoided massive redundant computations by deforming formulas according to the symmetries of prisms’integral regions,and the proposed algorithm parallelized this method’s computing process.The parallel algorithm was compared with a conventional serial algorithm using 100 elevation data in two topographic areas(rough and moderate terrain).Modeling differences between the two algorithms were less than 0.1 E,which is attributed to precision differences between single-precision and double-precision float numbers.The parallel algorithm showed computational efficiency approximately 200 times higher than the serial algorithm in experiments,demonstrating its effective speeding up in the modeling process.Further analysis indicates that both the modified method and computational parallelism through GPU contributed to the proposed algorithm’s performances in experiments.展开更多
Rapid solidification of Cu-Pb monotectic alloys has been accomplished during free fall in a 3 m drop tube. Both macrosegregated and uniformly dispersed structures are observed in Cu-40 wt pct Pb alloy droplets, wherea...Rapid solidification of Cu-Pb monotectic alloys has been accomplished during free fall in a 3 m drop tube. Both macrosegregated and uniformly dispersed structures are observed in Cu-40 wt pct Pb alloy droplets, whereas droplets of composition Cu-64 wt pct Pb exhibit only macrosegregation morphologies. The microstructures are strongly dependent on droplet size. The higher undercooling tends to facilitate liquid phase separation and results in more extensive macrosegregation in smaller droplets. There exists a pronounced tendency for the Pb-rich liquid to occupy the surface of the droplets of both compositions, resulting from the quite lower surface tension of the Pb-rich phase and causing a Pb-rich layer at the surface of the solidified droplet. The nucleation of monotectic cells in the Cu-40 wt pct Pb droplets with dispersed structures preferentially occurs at the droplet surface. A single nucleation event takes place more frequently as droplet size is reduced.展开更多
In combination with the Bagnold's shearing theory and the principle of Markov process,a mathematical model of sluice type's gravity concentrators has been developed based on the transfer probabilities of miner...In combination with the Bagnold's shearing theory and the principle of Markov process,a mathematical model of sluice type's gravity concentrators has been developed based on the transfer probabilities of mineral particles.According to the transfer probabilities,the quanti- tative relationship between the final separation results and feed variables has been established and verified by experimental data.The availability of this model is vital for process design and optimization or mill control of gravity concentration circuits.展开更多
In this paper, the adaptation process in low latitude atmosphere is discussed by means of a two-layer baroclinic model on the equator b plane, showing that the adaptation process in low latitude is mainly dominated by...In this paper, the adaptation process in low latitude atmosphere is discussed by means of a two-layer baroclinic model on the equator b plane, showing that the adaptation process in low latitude is mainly dominated by the internal inertial gravity waves. The initial ageostrophic energy is dispersed by the internal inertial gravity waves, and as a result, the geostrophic motion is obtained in zonal direction while the ageostro-phic motion maintains in meridional direction, which can be called semi-geostrophic balance in barotropic model as well as semi-thermal-wind balance in baroclinic model. The vertical motion is determined both by the distribution of the initial vertical motion and that of the initial vertical motion tendency, but it is unrelated to the initial potential vorticity. Finally, the motion tends to be horizontal. The discussion of the physical mecha-nism of the semi-thermal-wind balance in low latitude atmosphere shows that the achievement of the semi-thermal-wind balance is due to the adjustment between the stream field and the temperature field through the horizontal convergence and divergence which is related to the vertical motion excited by the internal inertial gravity waves. The terminal adaptation state obtained shows that the adaptation direction between the mean temperature field and the shear flow field is determined by the ratio of the scale of the initial ageostrophic dis-turbance to the scale of one character scale related to the baroclinic Rossby radius of deformation. The shear stream field adapts to the mean temperature field when the ratio is greater than 1, and the mean temperature field adapts to the shear stream field when the ratio is smaller than 1.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.52376181)。
文摘The melting process of a phase change material(PCM) inside a capsule can be promising in the thermal management of spacecraft. Such spacecraft operate under various gravity conditions, but previous studies have mostly considered the influence of gravity conditions on the constrained melting process of a PCM and not on its unconstrained melting process. In this study, a numerical model was constructed to comprehensively analyze the constrained and unconstrained melting processes of a PCM inside a spherical capsule under low-gravity conditions. After validation, the model was then applied to investigating the effects of low-gravity conditions on the evolution of velocity, temperature, melt layer thickness, heat transfer, liquid fraction, and total melting time. For the unconstrained melting process, low-gravity conditions weaken buoyancy-driven natural convection and slow down the solid PCM downward trend, thereby limiting the melting rate. In addition, the melt layer thickness does not increase linearly with decreasing gravity. Specifically, the increase in melt layer thickness is smaller by about 1.06 mm when the gravity drops from 0.4g to 0.2g compared to when it drops from 0.2g to 0.1g. The local heat flux in the contact melting area gradually decreases with the reduction of gravity during the unconstrained melting process. During the constrained melting process, notable oscillations in the local heat flux were observed. Decreasing the gravity from g to 0g increased the total melting times of the constrained and unconstrained melting processes by 417% and 621%, respectively.
文摘A novel method for noise removal from the rotating accelerometer gravity gradiometer(MAGG)is presented.It introduces a head-to-tail data expansion technique based on the zero-phase filtering principle.A scheme for determining band-pass filter parameters based on signal-to-noise ratio gain,smoothness index,and cross-correlation coefficient is designed using the Chebyshev optimal consistent approximation theory.Additionally,a wavelet denoising evaluation function is constructed,with the dmey wavelet basis function identified as most effective for processing gravity gradient data.The results of hard-in-the-loop simulation and prototype experiments show that the proposed processing method has shown a 14%improvement in the measurement variance of gravity gradient signals,and the measurement accuracy has reached within 4E,compared to other commonly used methods,which verifies that the proposed method effectively removes noise from the gradient signals,improved gravity gradiometry accuracy,and has certain technical insights for high-precision airborne gravity gradiometry.
文摘A novel process utilizing vertical wells to enhance heavy oil recovery during steam assisted gravity drainage has been developed. In the vertical well steam assisted gravity drainage (VWSAGD) process shown in Figure 1, the vertical well includes two production strings which are separated by three packers (one dual and two single packers): the short injection string (SIS) is attached to the bottom of the annulus and completed in the top quarter of the perforated formation, while the long production string (LPS) is attached to the bottom of the production tubing and completed in the bottom quarter of the perforated formation. The new process (VWSAGD) requires an initial start-up period (warm-up stage) where the steam is injected into both of the injection strings and production string for a specified period of time of about 14-30 days;then both strings are closed to injection for a specified time period of approximately 7 - 10 days (soaking period). After the initial warm-up and the soaking period, the long production string is opened for production, and the short injection string is opened to continuous steam injection for the rest of the specified simulation time. A commercial simulator (CMG-STAR Simulator) was used to study the performance of the new VWSAGD process. A sensitivity analysis was performed for the grid density, soaking time, steam quality, bottom hole producing pressure, steam injection rate, reservoir thickness, reservoir area, and horizontal to vertical permeability anisotropy. The results of this study have shown that the new VWSAGD process is more preferable for reservoir conditions such as high horizontal to vertical permeability ratio and thick reservoir oil zones.
文摘A numerical simulation study using the CMG-STAR Simulator was performed to compare the performance of the newly developed process (VWSAGD) utilizing vertical wells to enhance heavy oil recovery during steam assisted gravity drainage against the conventional steam assisted gravity drainage process which utilized horizontal wells (HWSAGD) under the same operating conditions. Two identical reservoir models were simulated for the two processes using 3-Dimensional, black heavy oil model (14° API). Each reservoir type consists of 49 × 49 × 20 grid blocks on a 5-acre model, which incorporated a typical heavy oil reservoir rock and fluid properties taken from the SPE case study, stspe001.dat (CMG 2015 release). A sensitivity analysis for both processes was performed for the grid density, soaking time, steam quality, bottom hole producing pressure, steam injection rate, reservoir thickness, reservoir area, and horizontal to vertical permeability anisotropy. More preferable reservoir conditions are those such as high horizontal to vertical permeability ratio, thick reservoir oil zones, as well as improved reservoir recovery for the VWSAGD process. Under unfavorable conditions such as thin reservoir oil zones, an improved reservoir recovery response was limited for the VWSAGD process and could be uneconomical in real field cases. Finally, the simulation results from this study include cumulative recoveries, Steam oil ratios, produced water-oil ratios, pressure and temperature distributions, and production rates. In addition, the results from this study have shown that the new VWSAGD process is more favorable than the conventional HWSAGD process.
基金National Key Research and Development Program of China(No.2020YFC1909202)Major Science and Technology Program of Yunnan Province,China(No.202202AB080012)for financial support。
文摘Copper and cobalt were recovered from SICOMINES mining waste rock in the Democratic Republic of Congo.The process mineralogy of the samples was analyzed using scanning electron microscopy and energy dispersive spectroscopy.The results showed that copper minerals exhibited various forms and uneven particle sizes,while cobalt existed in the form of highly dispersed asbolane,and large amounts of easily slimed gangue minerals were filled in the samples,making it difficult to separate copper and cobalt minerals.The particle size range plays a decisive role in selecting the separation method for the copper−cobalt ore.Gravity separation was suitable for particles ranging from 43 to 246μm,while flotation was more effective for particles below 43μm.After ore grinding and particle size classification,applying a combined gravity separation(shaking table)−flotation method yielded concentrated minerals with a copper recovery of 72.83%and a cobalt recovery of 31.13%.
基金supported by the National Natural Science Foundation of China(52104262)the Joint Funds of the National Natural Science Foundation of China(U23A20131)the National Key Research and Development Plan(2023YFB4103501,2022YFB4101604).
文摘Coal gasification fine slag(CGFS)is a solid waste produced in the process of coal gasification.The separation of residue carbon in CGFS is essential for its resource utilization.In this study,the basic physical properties of CGFS were analyzed and the effect of physical separation experiments were carried out.The gravity separation results indicated that the coarser particle size fraction achieved a good separation effect.The High-carbon product has a yield of 12.53% with an ash content of 16.84%,and the High-ash product has a yield of 17.85%with an ash content of 98.15% were obtained.Theoretical calculations indicated that the apparent density difference between residue carbon and ash minerals in the water phase environment was the basis for achieving separation.The Rich-ash product was further separated by magnetic separation,and both magnetic field characteristics,water elutriation frequency and grinding time had impacts on the magnetic separation effect.Compared to gravity separation alone,the combined gravity-magnetic separation further enhanced the separation effect of residue carbon and ash minerals.The ash content of the Rich-ash product decreased from 80.56% to 69.52% due to the removal of high-ash Fe oxides,and the yield of combined separation tailings increased from 17.85% to 41.75%.The characterization results obtained through SEM-EDS,VSM,XRD and XRF analysis demonstrated significant differences in saturation magnetization,mineral composition and peak intensity among magnetic separation products,confirming that the feasibility of magnetic separation.The research findings contribute to a better understanding of the separation mechanism and provide a new separation process for efficiently enriching residue carbon from CGFS,also facilitate the step utilization of separation products.
基金supported by National Geological Survey Projects (No. 1212010510903 and 200214100027)
文摘We developed the China Regional Gravity Information System（RGIS） using mixed language programming in Visual Basic,Visual C＋＋,and FORTRAN.The software is based on the MapInfo platform with OLE technology.With this system,we achieve visual data management for the database with spatial geography,geology data and gravity data as well as graphical data editing and data table operations over the whole of China.We are able to perform normalized gravity reduction,gravity and magnetic field transforms,gravity anomaly inversion and interpretation,thematic mapping and so on.
基金supported by the Special Earthquake Research ProjectGrant by China Earthquake Administration(201008007)NationalNatural Science Foundation of China(40874035)
文摘Absolute and relative gravity data during 1998 to 2008 were used to study gravity field and temporal variation in the North-South seismic-belt region, and their correlation with seismic activities before and after Wenchuan Ms8.0 earthquake. The temporal variation of gravity field shows that the portentous information of the gravity field reflects the development and occurrence of earthquake more clearly. The variations of gravity field are inhomogeneous in the space-time distribution, and are associated with the development and occurrence of the Wenchuan Ms8.0 earthquake, also closely connected with active fault tectonics.
基金financial support from the National Key Research and Development Program of China(2017YFB0404302/2017YFB0404300)National Natural Science Foundation of China(21808009,91934303)the Beijing Natural Science Foundation(2182051)。
文摘In this work,we report an innovative route for the synthesis of rare-earth doped calcium molybdate(CaMoO4)nanophosphors by using high gravity rotating packed bed(RPB)technology and paraffin liquid as the solvent.The significant intensified mass transfer and micromixing of reactants in the RPB reactor are benefiting for homogeneous doping of rare-earth ions in the host materials,leading to nanophosphors with high quantum efficiency.The use of liquid paraffin as the solvent eliminates the safety risks associated with volatile organic compounds,increasing the potential for clean production of nanophosphors.Under excitation of deep ultraviolet(DUV)light,the CaMoO4:Na+,Eu3+nanophosphors exhibit red emission at peak wavelength of 615 nm and quantum yield of up to 35.01%.The CaMoO4:Na+,Tb3+nanophosphors exhibit green emission at peak wavelength of543 nm with quantum yield of up to 30.66%.The morphologies of the nanophosphors are tunable from nanofibers through nanorods to nanodots and the possible mechanism of controlling the formation of different nanostructures is proposed on the basis of experimental results and theoretical analysis of mesoscience.These nanophosphors are highly dispersible in organic solvents and utilized for fabricating fabrication of flexible,freestanding luminescent films based on silicone resin.We also demonstrate the red LEDs consisting of the hybrid films of CaMoO4:Na+,Eu3+nanoparticles as color-converting phosphors and DUV LEDs as illuminators,offering strong potential for future nanophosphors-basedsolid-state lighting systems.
文摘The comprehensive evaluation of Tahe medium gravity crude has demonstrated that this type of crude belongs to a intermediate base sour crude, featuring high vanadium content (103ppm), high carbon residue content, low pour point, and low acid value. Based on the crude processing conditions at SINOPEC Luoyang Petrochemical Branch Company, a proposal on the appropriate process flow scheme for processing Tahe crude oil has been raised with the main ideas presented as follows. The IBP-175 fraction is not an ideal feedstock for catalytic reforming; the 75-250 fraction is a qualified feedstock for zeolite de-waxing; the 140-230 fraction can be used to manufacture the No. 3 jet fuel through appropriate distillation range adjustment and product refining; the 175-350 fraction can be directly used to manufacture No.-10 diesel through proper refining; the atmospheric resid boiling over 350 is not suited to be used as the RFCC feedstock; the 350-520 vacuum distillate oil can be used as the FCC feedstock; and the vacuum residuum boiling over 520 is a good feedstock for manufacture of asphalt.
文摘The gravity gradient is a secondary derivative of gravity potential,containing more high-frequency information of Earth’s gravity field.Gravity gradient observation data require deducting its prior and intrinsic parts to obtain more variational information.A model generated from a topographic surface database is more appropriate to represent gradiometric effects derived from near-surface mass,as other kinds of data can hardly reach the spatial resolution requirement.The rectangle prism method,namely an analytic integration of Newtonian potential integrals,is a reliable and commonly used approach to modeling gravity gradient,whereas its computing efficiency is extremely low.A modified rectangle prism method and a graphical processing unit(GPU)parallel algorithm were proposed to speed up the modeling process.The modified method avoided massive redundant computations by deforming formulas according to the symmetries of prisms’integral regions,and the proposed algorithm parallelized this method’s computing process.The parallel algorithm was compared with a conventional serial algorithm using 100 elevation data in two topographic areas(rough and moderate terrain).Modeling differences between the two algorithms were less than 0.1 E,which is attributed to precision differences between single-precision and double-precision float numbers.The parallel algorithm showed computational efficiency approximately 200 times higher than the serial algorithm in experiments,demonstrating its effective speeding up in the modeling process.Further analysis indicates that both the modified method and computational parallelism through GPU contributed to the proposed algorithm’s performances in experiments.
基金Financial support from the National Natural Science Founda tion of China(No.59871040 and 50071009)is gratefuly acknowledged.
文摘Rapid solidification of Cu-Pb monotectic alloys has been accomplished during free fall in a 3 m drop tube. Both macrosegregated and uniformly dispersed structures are observed in Cu-40 wt pct Pb alloy droplets, whereas droplets of composition Cu-64 wt pct Pb exhibit only macrosegregation morphologies. The microstructures are strongly dependent on droplet size. The higher undercooling tends to facilitate liquid phase separation and results in more extensive macrosegregation in smaller droplets. There exists a pronounced tendency for the Pb-rich liquid to occupy the surface of the droplets of both compositions, resulting from the quite lower surface tension of the Pb-rich phase and causing a Pb-rich layer at the surface of the solidified droplet. The nucleation of monotectic cells in the Cu-40 wt pct Pb droplets with dispersed structures preferentially occurs at the droplet surface. A single nucleation event takes place more frequently as droplet size is reduced.
文摘In combination with the Bagnold's shearing theory and the principle of Markov process,a mathematical model of sluice type's gravity concentrators has been developed based on the transfer probabilities of mineral particles.According to the transfer probabilities,the quanti- tative relationship between the final separation results and feed variables has been established and verified by experimental data.The availability of this model is vital for process design and optimization or mill control of gravity concentration circuits.
基金Foundation for Doctor Station of the State Education Council and Natural Science Founda-tion of China (No.19775260)
文摘In this paper, the adaptation process in low latitude atmosphere is discussed by means of a two-layer baroclinic model on the equator b plane, showing that the adaptation process in low latitude is mainly dominated by the internal inertial gravity waves. The initial ageostrophic energy is dispersed by the internal inertial gravity waves, and as a result, the geostrophic motion is obtained in zonal direction while the ageostro-phic motion maintains in meridional direction, which can be called semi-geostrophic balance in barotropic model as well as semi-thermal-wind balance in baroclinic model. The vertical motion is determined both by the distribution of the initial vertical motion and that of the initial vertical motion tendency, but it is unrelated to the initial potential vorticity. Finally, the motion tends to be horizontal. The discussion of the physical mecha-nism of the semi-thermal-wind balance in low latitude atmosphere shows that the achievement of the semi-thermal-wind balance is due to the adjustment between the stream field and the temperature field through the horizontal convergence and divergence which is related to the vertical motion excited by the internal inertial gravity waves. The terminal adaptation state obtained shows that the adaptation direction between the mean temperature field and the shear flow field is determined by the ratio of the scale of the initial ageostrophic dis-turbance to the scale of one character scale related to the baroclinic Rossby radius of deformation. The shear stream field adapts to the mean temperature field when the ratio is greater than 1, and the mean temperature field adapts to the shear stream field when the ratio is smaller than 1.
