The article，which discusses the relationship between the policy of flourishing China by science and（3ducatlon and continuing education， Is divided Into two parts，
The evaluation of the hot workability and applying it to hot rolling process are crucial for the optimization of microstructure of steel.In this study,the hot workability of Q 1100 steel was studied by a combination o...The evaluation of the hot workability and applying it to hot rolling process are crucial for the optimization of microstructure of steel.In this study,the hot workability of Q 1100 steel was studied by a combination of hot compression tests,hot rolling application,and microstructure characterization.The results show that the established recrystallization kinetic models can effectively predict stress variation during hot deformation.The calculated DRX volume fraction is positively related to deformation temperature,and negatively related to the strain rate and Zener-Hollomon parameter.Then the relationship between hot working parameters and microstructure evolution was established by drawing the hot processing maps.The hot processing maps were further applied to hot rolling.When the steel is rolled inside the optimum hot processing window,the macroscopic surface of the steel plate is relatively flat,and its microstructure is mainly composed of continuous dynamic recrystallization(CDRX)grains.The orientation difference between CDRX grains and the adjacent grains is small.When the steel is rolled inside the flow instability region,cracks appear on the macroscopic surface,and the microstructure includes deformed grains and discontinuous dynamic recrystallization(DDRX)grains.The DDRX grains have a large orientation difference with adjacent grains.展开更多
High-overload shocks are very likely to cause damage to the microstructure of MEMS devices, especially the continuous multiple high-overload shocks generated by the penetration of the multilayer target environment pos...High-overload shocks are very likely to cause damage to the microstructure of MEMS devices, especially the continuous multiple high-overload shocks generated by the penetration of the multilayer target environment pose more stringent challenges to its protective structure. In this study, the kinetic response model of the protective structure under single-pulse and continuous double-pulse impact is established,and a continuous double-pulse high overload impact test impact platform based on the sleeve-type bullet is constructed, and the protective performance of the multi-layer structure under multi-pulse is analyzed based on the acceleration decay ratio, and the results show that the protective performance of the structure has a positive correlation with its thickness, and it is not sensitive to the change of the load of the first impact;the first impact under double-pulse impact will cause damage to the microstructure through the superposition of the second impact. The first impact under double-pulse impact will cause an increase in the overload amplitude of the second impact through superposition;compared with the single-layer structure, the acceleration attenuation ratio of the double-layer structure can be increased by up to 26.13%, among which the epoxy-polyurethane combination has the best protection performance, with an acceleration attenuation ratio of up to 44.68%. This work provides a robust theoretical foundation and experimental basis for the reliable operation of MEMS devices, as well as for the design of protective structures in extreme environments.展开更多
Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especial...Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especially continuous wave(CW)THz near-field scanning microscopy(THz-SNOM)with its nanoscale reso⁃lution,can be promising in biomedical imaging.In addition,compared with traditional THz time-domain spec⁃troscopy(TDS),portable solid-state source as the emission has higher power and SNR,lower cost,and can ob⁃tain more precise imaging.In this study,we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale.We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens,mainly due to the decrease in permittivity.This new approach offers valuable insights into the micro⁃scopic processes of enamel demineralization,laying the foundation for further research and treatment.展开更多
For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial...For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.展开更多
The insensitive munitions compound nitroguanidine(NQ)is used by the U.S.Army to avoid unintended explosions.However,NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aq...The insensitive munitions compound nitroguanidine(NQ)is used by the U.S.Army to avoid unintended explosions.However,NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aquatic organisms,indicating the need for effective remediation strategies.Thus,we investigated the feasibility of treating water contaminated with NQ in continuous-flow columns packed with zero-valent iron(ZVI)or iron sulfide(FeS).Initially,the impact of pH on NQ transformation by ZVI or FeS was evaluated in batch experiments.The pseudo first-order rate constant for NQ transformation(k_(1,NQ))by ZVI was 8-10 times higher at pH 3.0 compared to pH 5.5 and 7.0,whereas similar k_(1,NQ)values were obtained for FeS at pH 5.5-10.0.Based on these findings,the influent p H fed to the ZVIand Fe S-packed columns was adjusted to 3.0 and 5.5,respectively.Both reactors transformed NQ into nitrosoguanidine(Nso Q).Further transformation of Nso Q by ZVI produced aminoguanidine,guanidine,and cyanamide,whereas Nso Q transformation by Fe S produced guanidine,ammonium,and traces of urea.ZVI outperformed Fe S as a reactive material to remove NQ.The ZVI-packed column effectively removed NQ below detection even after 45 d of operation(490 pore volumes,PV).In contrast,NQ breakthrough(removal efficiency<85%)was observed after 18 d(180 PV)in the Fe S-packed column.The high NQ removal efficiency and long service life of the ZVI-packed column(>490 PV)suggest that the technology is a promising approach for NQ treatment in packed-bed reactors and in situ remediation.展开更多
Range-azimuth imaging of ground targets via frequency-modulated continuous wave(FMCW)radar is crucial for effective target detection.However,when the pitch of the moving array constructed during motion exceeds the phy...Range-azimuth imaging of ground targets via frequency-modulated continuous wave(FMCW)radar is crucial for effective target detection.However,when the pitch of the moving array constructed during motion exceeds the physical array aperture,azimuth ambiguity occurs,making range-azimuth imaging on a moving platform challenging.To address this issue,we theoretically analyze azimuth ambiguity generation in sparse motion arrays and propose a dual-aperture adaptive processing(DAAP)method for suppressing azimuth ambiguity.This method combines spatial multiple-input multiple-output(MIMO)arrays with sparse motion arrays to achieve high-resolution range-azimuth imaging.In addition,an adaptive QR decomposition denoising method for sparse array signals based on iterative low-rank matrix approximation(LRMA)and regularized QR is proposed to preprocess sparse motion array signals.Simulations and experiments show that on a two-transmitter-four-receiver array,the signal-to-noise ratio(SNR)of the sparse motion array signal after noise suppression via adaptive QR decomposition can exceed 0 dB,and the azimuth ambiguity signal ratio(AASR)can be reduced to below-20 dB.展开更多
Better Medicines through Global Education and Research October 12,2015Dear Professor Du：On behalf of the International Union of Basic and Clinical Pharmacology（IUPHAR）we wish to extend our best wishes and congratul...Better Medicines through Global Education and Research October 12,2015Dear Professor Du：On behalf of the International Union of Basic and Clinical Pharmacology（IUPHAR）we wish to extend our best wishes and congratulations to you and your colleagues as you celebrate the 30th anni-versary of the founding of the Chinese Pharmacological Society（CNPHARS）.展开更多
With increasing globalization and a trend towards international harmonization of standards for the care and use of animals in research and testing,there is a significant need to assist and support countries to develop...With increasing globalization and a trend towards international harmonization of standards for the care and use of animals in research and testing,there is a significant need to assist and support countries to develop training programs for laboratory animal veterinarians.Although formal educational opportunities for training laboratory animal veterinarians exist through well-established specialty colleges of laboratory animal medicine such as ACLAM,ECLAM,JCLAM,and KCLAM or through other professional organisations,such as the Federation of European Laboratory Animal Science Associations(FELASA),opportunities for participating in these programs are often limited to veterinarians in North America,Western Europe and specific regions of Asia.Creative thinking is required to develop cost-effective,practical,entry-level and advanced continuing education and applied training programs for veterinarians working in the field of laboratory animal medicine around the world.This paper will describe one potential solution for this issue,the use of a distance education program that provides theoretical information in a virtual classroom with applied training modules to deliver knowledge and practical skills to laboratory animal veterinarians.This type of program takes advantage of the online learning environment and can be an effective means to deliver training at the grassroots level to adult learners.展开更多
Both Booker T.Washington and W.E.B.Du Bois are the prominent thinkers who provide inspirations for African Americans on their way to strive for political,economic and social emancipations.Their ideas arise from the sp...Both Booker T.Washington and W.E.B.Du Bois are the prominent thinkers who provide inspirations for African Americans on their way to strive for political,economic and social emancipations.Their ideas arise from the specific determinants of the historical period where they respectively live.People are often more aware of and interested in the differences and even conflicts of their propositions.In essence,thinking of the latter is a logic continuity of that of the former.Their ideas share a logic commonality,which is that they are conservative in the base,and reformist in the implementing steps.展开更多
Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete ...Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load.Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.展开更多
文摘The article，which discusses the relationship between the policy of flourishing China by science and（3ducatlon and continuing education， Is divided Into two parts，
基金Project(2018XK2301)supported by the Chang-Zhu-Tan National Independent Innovation Demonstration Zone Special Program,China。
文摘The evaluation of the hot workability and applying it to hot rolling process are crucial for the optimization of microstructure of steel.In this study,the hot workability of Q 1100 steel was studied by a combination of hot compression tests,hot rolling application,and microstructure characterization.The results show that the established recrystallization kinetic models can effectively predict stress variation during hot deformation.The calculated DRX volume fraction is positively related to deformation temperature,and negatively related to the strain rate and Zener-Hollomon parameter.Then the relationship between hot working parameters and microstructure evolution was established by drawing the hot processing maps.The hot processing maps were further applied to hot rolling.When the steel is rolled inside the optimum hot processing window,the macroscopic surface of the steel plate is relatively flat,and its microstructure is mainly composed of continuous dynamic recrystallization(CDRX)grains.The orientation difference between CDRX grains and the adjacent grains is small.When the steel is rolled inside the flow instability region,cracks appear on the macroscopic surface,and the microstructure includes deformed grains and discontinuous dynamic recrystallization(DDRX)grains.The DDRX grains have a large orientation difference with adjacent grains.
基金supported by Fund of the National Natural Science Foundation of China (Grant No. 52375553)。
文摘High-overload shocks are very likely to cause damage to the microstructure of MEMS devices, especially the continuous multiple high-overload shocks generated by the penetration of the multilayer target environment pose more stringent challenges to its protective structure. In this study, the kinetic response model of the protective structure under single-pulse and continuous double-pulse impact is established,and a continuous double-pulse high overload impact test impact platform based on the sleeve-type bullet is constructed, and the protective performance of the multi-layer structure under multi-pulse is analyzed based on the acceleration decay ratio, and the results show that the protective performance of the structure has a positive correlation with its thickness, and it is not sensitive to the change of the load of the first impact;the first impact under double-pulse impact will cause damage to the microstructure through the superposition of the second impact. The first impact under double-pulse impact will cause an increase in the overload amplitude of the second impact through superposition;compared with the single-layer structure, the acceleration attenuation ratio of the double-layer structure can be increased by up to 26.13%, among which the epoxy-polyurethane combination has the best protection performance, with an acceleration attenuation ratio of up to 44.68%. This work provides a robust theoretical foundation and experimental basis for the reliable operation of MEMS devices, as well as for the design of protective structures in extreme environments.
基金Supported by the National Natural Science Foundation of China(61988102,62401113,92463308)。
文摘Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especially continuous wave(CW)THz near-field scanning microscopy(THz-SNOM)with its nanoscale reso⁃lution,can be promising in biomedical imaging.In addition,compared with traditional THz time-domain spec⁃troscopy(TDS),portable solid-state source as the emission has higher power and SNR,lower cost,and can ob⁃tain more precise imaging.In this study,we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale.We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens,mainly due to the decrease in permittivity.This new approach offers valuable insights into the micro⁃scopic processes of enamel demineralization,laying the foundation for further research and treatment.
基金Supported by Projects from Chongqing Municipal Science and Technology Commission(CSTB2022NSCQ-MSX0445)。
文摘For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.
基金financially supported by the Strategic Environmental Research and Development Program(Grant No.ER19-1075)。
文摘The insensitive munitions compound nitroguanidine(NQ)is used by the U.S.Army to avoid unintended explosions.However,NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aquatic organisms,indicating the need for effective remediation strategies.Thus,we investigated the feasibility of treating water contaminated with NQ in continuous-flow columns packed with zero-valent iron(ZVI)or iron sulfide(FeS).Initially,the impact of pH on NQ transformation by ZVI or FeS was evaluated in batch experiments.The pseudo first-order rate constant for NQ transformation(k_(1,NQ))by ZVI was 8-10 times higher at pH 3.0 compared to pH 5.5 and 7.0,whereas similar k_(1,NQ)values were obtained for FeS at pH 5.5-10.0.Based on these findings,the influent p H fed to the ZVIand Fe S-packed columns was adjusted to 3.0 and 5.5,respectively.Both reactors transformed NQ into nitrosoguanidine(Nso Q).Further transformation of Nso Q by ZVI produced aminoguanidine,guanidine,and cyanamide,whereas Nso Q transformation by Fe S produced guanidine,ammonium,and traces of urea.ZVI outperformed Fe S as a reactive material to remove NQ.The ZVI-packed column effectively removed NQ below detection even after 45 d of operation(490 pore volumes,PV).In contrast,NQ breakthrough(removal efficiency<85%)was observed after 18 d(180 PV)in the Fe S-packed column.The high NQ removal efficiency and long service life of the ZVI-packed column(>490 PV)suggest that the technology is a promising approach for NQ treatment in packed-bed reactors and in situ remediation.
基金supported by the National Natural Science Foundation of China under Grant 62301051.
文摘Range-azimuth imaging of ground targets via frequency-modulated continuous wave(FMCW)radar is crucial for effective target detection.However,when the pitch of the moving array constructed during motion exceeds the physical array aperture,azimuth ambiguity occurs,making range-azimuth imaging on a moving platform challenging.To address this issue,we theoretically analyze azimuth ambiguity generation in sparse motion arrays and propose a dual-aperture adaptive processing(DAAP)method for suppressing azimuth ambiguity.This method combines spatial multiple-input multiple-output(MIMO)arrays with sparse motion arrays to achieve high-resolution range-azimuth imaging.In addition,an adaptive QR decomposition denoising method for sparse array signals based on iterative low-rank matrix approximation(LRMA)and regularized QR is proposed to preprocess sparse motion array signals.Simulations and experiments show that on a two-transmitter-four-receiver array,the signal-to-noise ratio(SNR)of the sparse motion array signal after noise suppression via adaptive QR decomposition can exceed 0 dB,and the azimuth ambiguity signal ratio(AASR)can be reduced to below-20 dB.
文摘Better Medicines through Global Education and Research October 12,2015Dear Professor Du：On behalf of the International Union of Basic and Clinical Pharmacology（IUPHAR）we wish to extend our best wishes and congratulations to you and your colleagues as you celebrate the 30th anni-versary of the founding of the Chinese Pharmacological Society（CNPHARS）.
文摘With increasing globalization and a trend towards international harmonization of standards for the care and use of animals in research and testing,there is a significant need to assist and support countries to develop training programs for laboratory animal veterinarians.Although formal educational opportunities for training laboratory animal veterinarians exist through well-established specialty colleges of laboratory animal medicine such as ACLAM,ECLAM,JCLAM,and KCLAM or through other professional organisations,such as the Federation of European Laboratory Animal Science Associations(FELASA),opportunities for participating in these programs are often limited to veterinarians in North America,Western Europe and specific regions of Asia.Creative thinking is required to develop cost-effective,practical,entry-level and advanced continuing education and applied training programs for veterinarians working in the field of laboratory animal medicine around the world.This paper will describe one potential solution for this issue,the use of a distance education program that provides theoretical information in a virtual classroom with applied training modules to deliver knowledge and practical skills to laboratory animal veterinarians.This type of program takes advantage of the online learning environment and can be an effective means to deliver training at the grassroots level to adult learners.
文摘Both Booker T.Washington and W.E.B.Du Bois are the prominent thinkers who provide inspirations for African Americans on their way to strive for political,economic and social emancipations.Their ideas arise from the specific determinants of the historical period where they respectively live.People are often more aware of and interested in the differences and even conflicts of their propositions.In essence,thinking of the latter is a logic continuity of that of the former.Their ideas share a logic commonality,which is that they are conservative in the base,and reformist in the implementing steps.
基金Project(51378503)supported by the National Natural Science Foundation of ChinaProject(2014M552158)supported by China Postdoctoral Science Foundation
文摘Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load.Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.
