Inter-crystalline pores, cavities, and fractures created from diagenetic shrinkage of dolomite are inter-connected each other, forming fine oil- and gas-bearing reservoirs. It is hard to predict these complex fracture...Inter-crystalline pores, cavities, and fractures created from diagenetic shrinkage of dolomite are inter-connected each other, forming fine oil- and gas-bearing reservoirs. It is hard to predict these complex fracture-cavity reservoirs because of their random distribution, different growth timing, and so on. Taking the lacustrine dolomite fracture-pore reservoir in the Lower Cretaceous Xiagou Formation in the Qingxi oilfield within the Jiuquan basin as an example, we put forward a comprehensive geophysical method to predict carbonate fractures.展开更多
Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO2 sequestration and in identifying the efficiency of CO2-enhanced oil recovery. Although geophysical monitoring techniq...Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO2 sequestration and in identifying the efficiency of CO2-enhanced oil recovery. Although geophysical monitoring techniques for CO2 sequestration have grown out of conventional oil and gas geophysical exploration techniques, it takes a long time to conduct geophysical monitoring, and there are many barriers and challenges. In this paper, with the initial objective of performing CO2 sequestration, we studied the geophysical tasks associated with evaluating geological storage sites and monitoring CO2 sequestration. Based on our review of the scope of geophysical monitoring techniques and our experience in domestic and international carbon capture and sequestration projects, we analyzed the inherent difficulties and our experiences in geophysical monitoring techniques, especially, with respect to 4D seismic acquisition, processing, and interpretation.展开更多
Density functional theory method has been employed to investigate the structures of the prototypical technetium-labeled diphosphonate complex 99mTc-MDP, where MDP represents methylenediphosphonic acid. A total of 14 t...Density functional theory method has been employed to investigate the structures of the prototypical technetium-labeled diphosphonate complex 99mTc-MDP, where MDP represents methylenediphosphonic acid. A total of 14 trial structures were generated by allowing for the geometric, conformational, charge, and spin isomerism. Based on the optimized structures and calculated energies at the B3LYP/LANL2DZ level, two stable isomers were determined for the title complex. And they were further studied systematically in comparison with the experimental structure. The basis sets 6-31G*(LANL2DZ for Tc), 6-31G*(cc-pVDZ-pp for Tc), and DGDZVP have also been employed in combination with the B3LYP functional to study the basis set effect on the geometries of isomers. The optimized structures agree well with the available experimental data, and the bond lengths are more sensitive to the basis set than the bond angles. The charge distributions were studied by the Mulliken population analysis and natural bond orbital analysis. The results reflect a significant ligand-to-metal electron donation.展开更多
The freshwater cyanobacterium, Cylindrospermopsis raciborskii (Woloszyflska) Seenayya and Subba Raju is a common species in lakes and reservoirs globally. In some areas of the world it can produce cytoand hepatotoxi...The freshwater cyanobacterium, Cylindrospermopsis raciborskii (Woloszyflska) Seenayya and Subba Raju is a common species in lakes and reservoirs globally. In some areas of the world it can produce cytoand hepatotoxins (cylindrospermopsins, saxitoxins), making blooms of this species a serious health concern for humans. In the last 10 15 years, there has been a considerable body of research conducted on the ecology, physiology and toxin production of this species and this paper reviews these studies with a focus on the cylindrospermopsin (CYN)-producing strains. C. raciborskii has low light requirements, close to neutral buoyancy, and a wide temperature tolerance, giving it the capacity to grow in many lentic waterbodies. It also has a flexible strategy with respect to nitrogen (N) utilisation; being able to switch between utilising fixed and atmospheric N as sources of N fluctuate. Additionally this species has a high phosphate (DIP) affinity and storage capacity. Like many cyanobacteria, it also has the capacity to use dissolved organic phosphorus (DOP). Changes in nutrient concentrations, light levels and temperature have also been found to affect production of the toxin CYN by this species. However, optimal toxin production does not necessarily occur when growth rates are optimal. Additionally, different strains of C. raciborskii vary in their cell quota of CYN, making it difficult to predict toxin concentrations, based on C. raciborskii cell densities. In summary, the ecological flexibility of this organism means that controlling blooms of C. raciborskii is a difficult undertaking. However, improved understanding of factors promoting the species and toxin production by genetically capable strains will lead to improved predictive models of blooms.展开更多
Physical properties including refractive index, density, viscosity and conductivity for binary mixtures of l-butyl- 3-methyl imidazolium chloride ([BMIM]CI) and different organic solvents at 298.15 K have been inves...Physical properties including refractive index, density, viscosity and conductivity for binary mixtures of l-butyl- 3-methyl imidazolium chloride ([BMIM]CI) and different organic solvents at 298.15 K have been investigated. Ex- cess molar volumes have been calculated and obtained data has been fitted by the Redlich-Kister equation. The density and refractive index were found to increase with increasing concentration of [BMIM]CI, however, excep- tions do exist as in the case of dimethyl sulfoxide (DMSO)/[BMIM]CI. For DMSO/[BMIM]CI, the density decreases with increasing concentration. The addition of different organic solvents was able to disrupt the interactions within mixtures, leading to free mobility of ions. The free mobility of ions has been found to enhance conductivity and decrease viscosity to varying extents in all mixtures studied. It has been observed that solubility parameters, dielectric constants and composition of the solvents used play a vital role in determining the resultant properties. The data obtained will play an important role in understanding the effect of the addition of organic solvents in ILs to enhance their applicability.展开更多
The chemistry version of the Weather Re- search and Forecasting model (WRF/Chem) was coupled with the anthropogenic emission inventory of David Streets to investigate the impacts of secondary aerosols on a persisten...The chemistry version of the Weather Re- search and Forecasting model (WRF/Chem) was coupled with the anthropogenic emission inventory of David Streets to investigate the impacts of secondary aerosols on a persistent fog event from 25 to 26 October 2007, in Northem China. The spatial distribution of the simulated fog is consistent with satellite observations, and the time-height distributions of the simulated boundary layer where the fog formed are also in good agreement with these observations. The sensitivity studies show that the secondary aerosols of SO4, NO3, and NH4 formed from gaseous precursors of SO2, NOx, and NH3 had substantial impacts on the formation processes and microphysical structure of the fog event. The decrease of the secondary aerosols obviously reduced the liquid water path and column droplet number concentration of the fog below the 1-km layer, and the corresponding area-averaged liquid water path and droplet number concentration of the fog decreased by 43% and 79%, respectively. The concentra- tions of NOx and NO3 were found to be extremely high in this case. The concentration of interstitial aerosol NO3 was much higher than the SO4 and NH4, but the concentration of SO4 was highest in the cloud-borne aerosols. The average activation ratios for SO4, NO3, and NH4 were 34%, 31%, and 30%, respectively, and the maximum ra- tios reached 62%, 86%, and 55% during the fog episode.展开更多
observation data obtained in a mesoscale convective system are compared to Weather Research and Forecasting(WRF)model simulations using four microphysics schemes(Morrison,WSM6,P3,SBM)with different complexities.The ma...observation data obtained in a mesoscale convective system are compared to Weather Research and Forecasting(WRF)model simulations using four microphysics schemes(Morrison,WSM6,P3,SBM)with different complexities.The main purpose of this paper is to assess the performance of the microphysics ensemble in terms of cloud microphysical properties.Results show that although the vertical distributions of liquid water content(LWC)and ice water content(IWC)simulated by the four members are quite different in the convective cloud region,they are relatively uniform in the stratiform cloud region.Overall,the results of the Morrison scheme are very similar to the ensemble average,and both of them are closer to the observations compared to the other schemes.Besides,the authors also note that all members still overpredict the LWC by a factor of 2–8 in some regions,resulting in large deviation between the observation and ensemble average.展开更多
Energy consumption of block-cutting machines represents a major cost item in the processing of travertines and other natural stones. Therefore, determining the optimum sawing conditions for a particular stone is of ma...Energy consumption of block-cutting machines represents a major cost item in the processing of travertines and other natural stones. Therefore, determining the optimum sawing conditions for a particular stone is of major importance in the natural stone-processing industry. An experimental study was carried out utilizing a fully instrumented block-cutter to investigate the sawing performances of five different types of travertine blocks during cutting with a circular diamond saw. The sawing tests were performed in the down-cutting mode. Performance measurements were determined by measuring the cutting speed and energy consumption. Then, specific energy was determined. The one main cutting parameter, cutting speed, was varied in the investigation of optimum cutting performance. Furthermore, some physico-mechanical properties of file travertine blocks were determined in the laboratory. As a result, it is found that the energy consumption (specific energy) of block cutting machines is highly affected by cutting speed. It is determined that specific energy value usually decreases when cutting speed increases. When the cutting speed is higher than the determined value, the diamond saw can become stuck in the travertine block; this situation can be a problem for the block-cutting machine. As a result, the optimum cutting speed obtained for the travertine mines examined is approximately 1.5-2.0 m/min.展开更多
For a physics system which exhibits memory,if memory is preserved only at points of random self-similar fractals,we define random memory functions and give the connection between the expectation of flux and the fracti...For a physics system which exhibits memory,if memory is preserved only at points of random self-similar fractals,we define random memory functions and give the connection between the expectation of flux and the fractional integral.In particular,when memory sets degenerate to Cantor type fractals or non-random self-similar fractals our results coincide with that of Nigmatullin and Ren et al.展开更多
Shear wave velocity Vs is measured by the surface geophysical survey like MASW (multi-channel surface wave analysis) or RWM (refraction wave method) and by the subsurface method like PS logging. PS logging and RWM...Shear wave velocity Vs is measured by the surface geophysical survey like MASW (multi-channel surface wave analysis) or RWM (refraction wave method) and by the subsurface method like PS logging. PS logging and RWM are direct methods to derive shear wave velocity and MASW retrieves shear wave through the inversion of the surface wave. In this work, the effectiveness of surface methods (MASW and RWM) is compared with PS logging in determining shear wave velocity. For this purpose, shear wave velocity results Vs30 of 12 PS logging and MASW surveys conducted in Mymensingh Municipality in Bangladesh have been utilized. Additionally, the shear wave velocity results of three PS logging have been compared with the refraction profiles of RWM survey conducted in Rooppur nuclear power plant site in Bangladesh. The relative discrepancy between RWM and PS logging is found less (ranges from -3.92 to 0.93) compared to MASW and PS logging (+/-0.88 to 33.92). The correlation coefficient of Vs30 derived from RWM and PS logging is observed much better (0.60) compared to MASW and PS logging (0.40). The result is good considering the lateral lithologic variability and inherent differences among techniques. It is evident from the comparison that the RWM can be used as a cost-effective alternative to traditional borehole PS logging method for Vs30 determination and thus the number of down-hole logging tests might be significantly reduced.展开更多
The seismic velocities are strongly influenced by porosity and degree of water saturation, as well as other petrophysical properties, such as density and elastic properties of the rocks. In this paper, the saturation ...The seismic velocities are strongly influenced by porosity and degree of water saturation, as well as other petrophysical properties, such as density and elastic properties of the rocks. In this paper, the saturation of water percentage for sandstones (SW%) has been calculated by mathematical equation, which is based on the relation between the seismic velocity of water to the seismic velocity obtained in the field (for p-wave velocity only). The results of this equation which ranged between (30% to 100%) are connected with the results of seismic velocity-porosity relation for saturated sandstone through model, this model can be used for determining the porosity (Φ) and water saturation percentage (SW%) of the sandstones in the same time.展开更多
文摘Inter-crystalline pores, cavities, and fractures created from diagenetic shrinkage of dolomite are inter-connected each other, forming fine oil- and gas-bearing reservoirs. It is hard to predict these complex fracture-cavity reservoirs because of their random distribution, different growth timing, and so on. Taking the lacustrine dolomite fracture-pore reservoir in the Lower Cretaceous Xiagou Formation in the Qingxi oilfield within the Jiuquan basin as an example, we put forward a comprehensive geophysical method to predict carbonate fractures.
基金supported by National 863 Program Grant 2012AA050103 and Grant 2011KTCQ03-09
文摘Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO2 sequestration and in identifying the efficiency of CO2-enhanced oil recovery. Although geophysical monitoring techniques for CO2 sequestration have grown out of conventional oil and gas geophysical exploration techniques, it takes a long time to conduct geophysical monitoring, and there are many barriers and challenges. In this paper, with the initial objective of performing CO2 sequestration, we studied the geophysical tasks associated with evaluating geological storage sites and monitoring CO2 sequestration. Based on our review of the scope of geophysical monitoring techniques and our experience in domestic and international carbon capture and sequestration projects, we analyzed the inherent difficulties and our experiences in geophysical monitoring techniques, especially, with respect to 4D seismic acquisition, processing, and interpretation.
基金This work was supported by the National Natural Science Foundation of China (No.20801024 and No.21001055), the Natural Science Foundation of Jiangsu Province (No.BK2009077), and the Science Foundation of Health Department of Jiangsu Province (No.H200963).
文摘Density functional theory method has been employed to investigate the structures of the prototypical technetium-labeled diphosphonate complex 99mTc-MDP, where MDP represents methylenediphosphonic acid. A total of 14 trial structures were generated by allowing for the geometric, conformational, charge, and spin isomerism. Based on the optimized structures and calculated energies at the B3LYP/LANL2DZ level, two stable isomers were determined for the title complex. And they were further studied systematically in comparison with the experimental structure. The basis sets 6-31G*(LANL2DZ for Tc), 6-31G*(cc-pVDZ-pp for Tc), and DGDZVP have also been employed in combination with the B3LYP functional to study the basis set effect on the geometries of isomers. The optimized structures agree well with the available experimental data, and the bond lengths are more sensitive to the basis set than the bond angles. The charge distributions were studied by the Mulliken population analysis and natural bond orbital analysis. The results reflect a significant ligand-to-metal electron donation.
文摘The freshwater cyanobacterium, Cylindrospermopsis raciborskii (Woloszyflska) Seenayya and Subba Raju is a common species in lakes and reservoirs globally. In some areas of the world it can produce cytoand hepatotoxins (cylindrospermopsins, saxitoxins), making blooms of this species a serious health concern for humans. In the last 10 15 years, there has been a considerable body of research conducted on the ecology, physiology and toxin production of this species and this paper reviews these studies with a focus on the cylindrospermopsin (CYN)-producing strains. C. raciborskii has low light requirements, close to neutral buoyancy, and a wide temperature tolerance, giving it the capacity to grow in many lentic waterbodies. It also has a flexible strategy with respect to nitrogen (N) utilisation; being able to switch between utilising fixed and atmospheric N as sources of N fluctuate. Additionally this species has a high phosphate (DIP) affinity and storage capacity. Like many cyanobacteria, it also has the capacity to use dissolved organic phosphorus (DOP). Changes in nutrient concentrations, light levels and temperature have also been found to affect production of the toxin CYN by this species. However, optimal toxin production does not necessarily occur when growth rates are optimal. Additionally, different strains of C. raciborskii vary in their cell quota of CYN, making it difficult to predict toxin concentrations, based on C. raciborskii cell densities. In summary, the ecological flexibility of this organism means that controlling blooms of C. raciborskii is a difficult undertaking. However, improved understanding of factors promoting the species and toxin production by genetically capable strains will lead to improved predictive models of blooms.
基金the National Natural Science Foundation of China(51273041)
文摘Physical properties including refractive index, density, viscosity and conductivity for binary mixtures of l-butyl- 3-methyl imidazolium chloride ([BMIM]CI) and different organic solvents at 298.15 K have been investigated. Ex- cess molar volumes have been calculated and obtained data has been fitted by the Redlich-Kister equation. The density and refractive index were found to increase with increasing concentration of [BMIM]CI, however, excep- tions do exist as in the case of dimethyl sulfoxide (DMSO)/[BMIM]CI. For DMSO/[BMIM]CI, the density decreases with increasing concentration. The addition of different organic solvents was able to disrupt the interactions within mixtures, leading to free mobility of ions. The free mobility of ions has been found to enhance conductivity and decrease viscosity to varying extents in all mixtures studied. It has been observed that solubility parameters, dielectric constants and composition of the solvents used play a vital role in determining the resultant properties. The data obtained will play an important role in understanding the effect of the addition of organic solvents in ILs to enhance their applicability.
基金supported by the National Meteorology Public Welfare Industry Research Project(GYHY200806001)the National Science and Technology Support Program (2006BAC12B03)
文摘The chemistry version of the Weather Re- search and Forecasting model (WRF/Chem) was coupled with the anthropogenic emission inventory of David Streets to investigate the impacts of secondary aerosols on a persistent fog event from 25 to 26 October 2007, in Northem China. The spatial distribution of the simulated fog is consistent with satellite observations, and the time-height distributions of the simulated boundary layer where the fog formed are also in good agreement with these observations. The sensitivity studies show that the secondary aerosols of SO4, NO3, and NH4 formed from gaseous precursors of SO2, NOx, and NH3 had substantial impacts on the formation processes and microphysical structure of the fog event. The decrease of the secondary aerosols obviously reduced the liquid water path and column droplet number concentration of the fog below the 1-km layer, and the corresponding area-averaged liquid water path and droplet number concentration of the fog decreased by 43% and 79%, respectively. The concentra- tions of NOx and NO3 were found to be extremely high in this case. The concentration of interstitial aerosol NO3 was much higher than the SO4 and NH4, but the concentration of SO4 was highest in the cloud-borne aerosols. The average activation ratios for SO4, NO3, and NH4 were 34%, 31%, and 30%, respectively, and the maximum ra- tios reached 62%, 86%, and 55% during the fog episode.
基金supported by the National Key R&D Program of Chinagrant number 2018YFC1507900the Demonstration Project of Artificial Precipitation Enhancement and Hail Suppression Operation Technology at the Eastern Side of the Taihang Mountains grant number hbrywcsy-2017-2sponsored by the National Natural Science Foundation of China grant numbers 41530427 and 41875172。
文摘observation data obtained in a mesoscale convective system are compared to Weather Research and Forecasting(WRF)model simulations using four microphysics schemes(Morrison,WSM6,P3,SBM)with different complexities.The main purpose of this paper is to assess the performance of the microphysics ensemble in terms of cloud microphysical properties.Results show that although the vertical distributions of liquid water content(LWC)and ice water content(IWC)simulated by the four members are quite different in the convective cloud region,they are relatively uniform in the stratiform cloud region.Overall,the results of the Morrison scheme are very similar to the ensemble average,and both of them are closer to the observations compared to the other schemes.Besides,the authors also note that all members still overpredict the LWC by a factor of 2–8 in some regions,resulting in large deviation between the observation and ensemble average.
文摘Energy consumption of block-cutting machines represents a major cost item in the processing of travertines and other natural stones. Therefore, determining the optimum sawing conditions for a particular stone is of major importance in the natural stone-processing industry. An experimental study was carried out utilizing a fully instrumented block-cutter to investigate the sawing performances of five different types of travertine blocks during cutting with a circular diamond saw. The sawing tests were performed in the down-cutting mode. Performance measurements were determined by measuring the cutting speed and energy consumption. Then, specific energy was determined. The one main cutting parameter, cutting speed, was varied in the investigation of optimum cutting performance. Furthermore, some physico-mechanical properties of file travertine blocks were determined in the laboratory. As a result, it is found that the energy consumption (specific energy) of block cutting machines is highly affected by cutting speed. It is determined that specific energy value usually decreases when cutting speed increases. When the cutting speed is higher than the determined value, the diamond saw can become stuck in the travertine block; this situation can be a problem for the block-cutting machine. As a result, the optimum cutting speed obtained for the travertine mines examined is approximately 1.5-2.0 m/min.
文摘For a physics system which exhibits memory,if memory is preserved only at points of random self-similar fractals,we define random memory functions and give the connection between the expectation of flux and the fractional integral.In particular,when memory sets degenerate to Cantor type fractals or non-random self-similar fractals our results coincide with that of Nigmatullin and Ren et al.
文摘Shear wave velocity Vs is measured by the surface geophysical survey like MASW (multi-channel surface wave analysis) or RWM (refraction wave method) and by the subsurface method like PS logging. PS logging and RWM are direct methods to derive shear wave velocity and MASW retrieves shear wave through the inversion of the surface wave. In this work, the effectiveness of surface methods (MASW and RWM) is compared with PS logging in determining shear wave velocity. For this purpose, shear wave velocity results Vs30 of 12 PS logging and MASW surveys conducted in Mymensingh Municipality in Bangladesh have been utilized. Additionally, the shear wave velocity results of three PS logging have been compared with the refraction profiles of RWM survey conducted in Rooppur nuclear power plant site in Bangladesh. The relative discrepancy between RWM and PS logging is found less (ranges from -3.92 to 0.93) compared to MASW and PS logging (+/-0.88 to 33.92). The correlation coefficient of Vs30 derived from RWM and PS logging is observed much better (0.60) compared to MASW and PS logging (0.40). The result is good considering the lateral lithologic variability and inherent differences among techniques. It is evident from the comparison that the RWM can be used as a cost-effective alternative to traditional borehole PS logging method for Vs30 determination and thus the number of down-hole logging tests might be significantly reduced.
文摘The seismic velocities are strongly influenced by porosity and degree of water saturation, as well as other petrophysical properties, such as density and elastic properties of the rocks. In this paper, the saturation of water percentage for sandstones (SW%) has been calculated by mathematical equation, which is based on the relation between the seismic velocity of water to the seismic velocity obtained in the field (for p-wave velocity only). The results of this equation which ranged between (30% to 100%) are connected with the results of seismic velocity-porosity relation for saturated sandstone through model, this model can be used for determining the porosity (Φ) and water saturation percentage (SW%) of the sandstones in the same time.