In this study,the cylindrical finite-volume method(FVM)is advanced for the efficient and high-precision simulation of the logging while drilling(LWD)orthogonal azimuth electromagnetic tool(OAEMT)response in a three-di...In this study,the cylindrical finite-volume method(FVM)is advanced for the efficient and high-precision simulation of the logging while drilling(LWD)orthogonal azimuth electromagnetic tool(OAEMT)response in a three-dimensional(3 D)anisotropic formation.To overcome the ill-condition and convergence problems arising from the low induction number,Maxwell’s equations are reformulated into a mixed Helmholtz equation for the coupled potentials in a cylindrical coordinate system.The electrical fi eld continuation method is applied to approximate the perfectly electrical conducting(PEC)boundary condition,to improve the discretization accuracy of the Helmholtz equation on the surface of metal mandrels.On the base,the 3 D FVM on Lebedev’s staggered grids in the cylindrical coordinates is employed to discretize the mixed equations to ensure good conformity with typical well-logging tool geometries.The equivalent conductivity in a non-uniform element is determined by a standardization technique.The direct solver,PARDISO,is applied to efficiently solve the sparse linear equation systems for the multi-transmitter problem.To reduce the number of calls to PARDISO,the whole computational domain is divided into small windows that contain multiple measuring points.The electromagnetic(EM)solutions produced by all the transmitters per window are simultaneously solved because the discrete matrix,relevant to all the transmitters in the same window,is changed.Finally,the 3 D FVM is validated against the numerical mode matching method(NMM),and the characteristics of both the coaxial and coplanar responses of the EM field tool are investigated using the numerical results.展开更多
The Lancaster House negotiations from September 1979 to the close of the year sought to bring to an end the chapter of the Second Chimurenga of Zimbabwe. Outside discussions on the land issue, one of the agreements ma...The Lancaster House negotiations from September 1979 to the close of the year sought to bring to an end the chapter of the Second Chimurenga of Zimbabwe. Outside discussions on the land issue, one of the agreements made at the Lancaster was that 12 Assembly Points be set up throughout the country to house guerrillas and initiate a demobilising exercise. Each was to be manned by a small contingent of the British Army and all the Zimbabwean National Liberation Army （ZANLA） and Zimbabwe People＇s Revolution Army （ZIPRA） guerrillas, in any one area, were to go to the closest assembly point. The Assembly Points, which included Dzapasi/Foxtrot in Buhera, Chitungwiza, Connemara, and Mike in Lupane, at one time housed 17,000 guerrillas. Tension was very high inside and outside these Assembly Points. In 1980, there were sporadic outbursts of violence around these points all over the country. The fights recurred in 1983 killing over 300 people. This research proposes to pore over the nature of the violence in this historical epoch to try and understand its roots as well as to establish whether attempts at accountability, reconciliation, healing, and integration were made after the Assembly Points era and if not, whither Zimbabwe？展开更多
Since the turn of the 21st century, the central government in Zimbabwe encouraged community participation in natural resources utilization. The research intends to understand the efficacy of this paradigm shift on sus...Since the turn of the 21st century, the central government in Zimbabwe encouraged community participation in natural resources utilization. The research intends to understand the efficacy of this paradigm shift on sustainable wetland utilization in communal areas, focusing specifically on Chebvute wetland in Zvishavane district of Zimbabwe. Research data was gathered through questionnaires, semi-structured interviews, direct observations and field measurements. These instruments targeted 19 purposively selected plot holders, project chairperson, Environmental Management Agency officer, Agritex officer and the headman. Mapping of the wetland area and its landuse was done using global positioning system receivers and the map was produced using ILWIS, ArcView and Google Earth images. Research findings revealed that the conserved wetland increased its size and biodiversity. Generally, all crops grown had estimated yields higher than the national averages per hectare. The average maize yield was 2.726 tonnes per hectare compared to national average of 0.87. However, conflicts between plot holders, other community members and officials from government institutions such as Environmental Management Agency and Agritex should be ironed out in order to safeguard the wetland＇s future.展开更多
The research centered on the groundwater quality parameters in five boreholes and three wells in residential urban areas of Zimbabwe. Ten runs of chemical analysis for water pH, EC （electrical conductivity）, water h...The research centered on the groundwater quality parameters in five boreholes and three wells in residential urban areas of Zimbabwe. Ten runs of chemical analysis for water pH, EC （electrical conductivity）, water hardness were carried out weekly and averages were calculated for each at Bindura University laboratory. Iron concentrations analysis was done at the Tobacco Research Station. The results from boreholes and wells were compared to the WHO （World Health Organisation） drinking water acceptable standards to measure the deviations. It was found that the boreholes had hard waters （112 mg/L）, EC （425 s/m） and iron concentration （0.49 ppm） outside the WHO standards （〉 64 mg/L; 400 s/m; 0.3 ppm respectively）. In contrary the wells had only the water pH slightly outside the acceptable ranges （5.8）; other parameters were in the acceptable ranges （EC 379 s/m; water hardness 0.38 mg/L as CaCO3 and iron concentration 0.38 ppm）. The difference in chemical composition between the boreholes and wells caused the borehole water rejection in favor of well water. High iron concentrations and water hardness in boreholes were major contributors to the water rejection by the residents.展开更多
A tablet consisting of direct-acting antiviral agents,ledipasvir（a NS5 A protein inhibitor） and sofosbuvir（a NS5 B polymerase inhibitor）,is the first fixed-dose preparation used in the antiviral therapy of hepatit...A tablet consisting of direct-acting antiviral agents,ledipasvir（a NS5 A protein inhibitor） and sofosbuvir（a NS5 B polymerase inhibitor）,is the first fixed-dose preparation used in the antiviral therapy of hepatitis C.A model-based meta-analysis of ledipasvir and GS331007,the primary metabolite of sofosbuvir,enabled the integration of pharmacokinetic（PK） information from separate clinical trials and the quantitative characterization of the population pharmacokinetics of these two drugs.A systematic publication search was conducted for the clinical studies of ledipasvir and sofosbuvir.A total of 401 arm-level aggregate concentrations of GS331007 and 188 concentrations of ledipasvir were used for PK modeling.A two-compartment disposition model was used for both ledipasvir and GS331007.Zero-order absorption was applied for ledipasvir PK modeling,and a combined zero- and first-order absorption was used for the modeling of GS331007.Absorption lag was observed in concentration-time profiles of both ledipasvir and GS331007.To aid the development of direct-acting antiviral drugs,our established PK models provided a basis for the further PK-viral kinetic studies of ledipasvir and sofosbuvir.展开更多
基金supported jointly by Strategic Pilot Science and Technology Project of Chinese Academy of Sciences (No. XDA14020102)National key research and development plan (No. 2017YFC0601805)+5 种基金National Natural Science Foundation of China (No. 41574110)Youth Foundation of Hebei Educational Committee (No. QN2018217)Hebei Higher Education Teaching Reform Research and Practice(No. 2018GJJG328)Zhangjiakou science and technology bureau(No. 1821011B)Doctoral Fund of Hebei Institute of Architecture and Civil Engineering (No. B-201606)Academic Team Innovation Ability Improvement Project of Hebei Institute of Architecture and Civil Engineering(TD202011)。
文摘In this study,the cylindrical finite-volume method(FVM)is advanced for the efficient and high-precision simulation of the logging while drilling(LWD)orthogonal azimuth electromagnetic tool(OAEMT)response in a three-dimensional(3 D)anisotropic formation.To overcome the ill-condition and convergence problems arising from the low induction number,Maxwell’s equations are reformulated into a mixed Helmholtz equation for the coupled potentials in a cylindrical coordinate system.The electrical fi eld continuation method is applied to approximate the perfectly electrical conducting(PEC)boundary condition,to improve the discretization accuracy of the Helmholtz equation on the surface of metal mandrels.On the base,the 3 D FVM on Lebedev’s staggered grids in the cylindrical coordinates is employed to discretize the mixed equations to ensure good conformity with typical well-logging tool geometries.The equivalent conductivity in a non-uniform element is determined by a standardization technique.The direct solver,PARDISO,is applied to efficiently solve the sparse linear equation systems for the multi-transmitter problem.To reduce the number of calls to PARDISO,the whole computational domain is divided into small windows that contain multiple measuring points.The electromagnetic(EM)solutions produced by all the transmitters per window are simultaneously solved because the discrete matrix,relevant to all the transmitters in the same window,is changed.Finally,the 3 D FVM is validated against the numerical mode matching method(NMM),and the characteristics of both the coaxial and coplanar responses of the EM field tool are investigated using the numerical results.
文摘The Lancaster House negotiations from September 1979 to the close of the year sought to bring to an end the chapter of the Second Chimurenga of Zimbabwe. Outside discussions on the land issue, one of the agreements made at the Lancaster was that 12 Assembly Points be set up throughout the country to house guerrillas and initiate a demobilising exercise. Each was to be manned by a small contingent of the British Army and all the Zimbabwean National Liberation Army （ZANLA） and Zimbabwe People＇s Revolution Army （ZIPRA） guerrillas, in any one area, were to go to the closest assembly point. The Assembly Points, which included Dzapasi/Foxtrot in Buhera, Chitungwiza, Connemara, and Mike in Lupane, at one time housed 17,000 guerrillas. Tension was very high inside and outside these Assembly Points. In 1980, there were sporadic outbursts of violence around these points all over the country. The fights recurred in 1983 killing over 300 people. This research proposes to pore over the nature of the violence in this historical epoch to try and understand its roots as well as to establish whether attempts at accountability, reconciliation, healing, and integration were made after the Assembly Points era and if not, whither Zimbabwe？
文摘Since the turn of the 21st century, the central government in Zimbabwe encouraged community participation in natural resources utilization. The research intends to understand the efficacy of this paradigm shift on sustainable wetland utilization in communal areas, focusing specifically on Chebvute wetland in Zvishavane district of Zimbabwe. Research data was gathered through questionnaires, semi-structured interviews, direct observations and field measurements. These instruments targeted 19 purposively selected plot holders, project chairperson, Environmental Management Agency officer, Agritex officer and the headman. Mapping of the wetland area and its landuse was done using global positioning system receivers and the map was produced using ILWIS, ArcView and Google Earth images. Research findings revealed that the conserved wetland increased its size and biodiversity. Generally, all crops grown had estimated yields higher than the national averages per hectare. The average maize yield was 2.726 tonnes per hectare compared to national average of 0.87. However, conflicts between plot holders, other community members and officials from government institutions such as Environmental Management Agency and Agritex should be ironed out in order to safeguard the wetland＇s future.
文摘The research centered on the groundwater quality parameters in five boreholes and three wells in residential urban areas of Zimbabwe. Ten runs of chemical analysis for water pH, EC （electrical conductivity）, water hardness were carried out weekly and averages were calculated for each at Bindura University laboratory. Iron concentrations analysis was done at the Tobacco Research Station. The results from boreholes and wells were compared to the WHO （World Health Organisation） drinking water acceptable standards to measure the deviations. It was found that the boreholes had hard waters （112 mg/L）, EC （425 s/m） and iron concentration （0.49 ppm） outside the WHO standards （〉 64 mg/L; 400 s/m; 0.3 ppm respectively）. In contrary the wells had only the water pH slightly outside the acceptable ranges （5.8）; other parameters were in the acceptable ranges （EC 379 s/m; water hardness 0.38 mg/L as CaCO3 and iron concentration 0.38 ppm）. The difference in chemical composition between the boreholes and wells caused the borehole water rejection in favor of well water. High iron concentrations and water hardness in boreholes were major contributors to the water rejection by the residents.
基金Janssen Research & DevelopmentChina，Pfizer Scholarship for Pharmacometrics during this project
文摘A tablet consisting of direct-acting antiviral agents,ledipasvir（a NS5 A protein inhibitor） and sofosbuvir（a NS5 B polymerase inhibitor）,is the first fixed-dose preparation used in the antiviral therapy of hepatitis C.A model-based meta-analysis of ledipasvir and GS331007,the primary metabolite of sofosbuvir,enabled the integration of pharmacokinetic（PK） information from separate clinical trials and the quantitative characterization of the population pharmacokinetics of these two drugs.A systematic publication search was conducted for the clinical studies of ledipasvir and sofosbuvir.A total of 401 arm-level aggregate concentrations of GS331007 and 188 concentrations of ledipasvir were used for PK modeling.A two-compartment disposition model was used for both ledipasvir and GS331007.Zero-order absorption was applied for ledipasvir PK modeling,and a combined zero- and first-order absorption was used for the modeling of GS331007.Absorption lag was observed in concentration-time profiles of both ledipasvir and GS331007.To aid the development of direct-acting antiviral drugs,our established PK models provided a basis for the further PK-viral kinetic studies of ledipasvir and sofosbuvir.
