The detection of hypersonic targets usually confronts range migration(RM)issue before coherent integration(CI).The traditional methods aiming at correcting RM to obtain CI mainly considers the narrow-band radar condit...The detection of hypersonic targets usually confronts range migration(RM)issue before coherent integration(CI).The traditional methods aiming at correcting RM to obtain CI mainly considers the narrow-band radar condition.However,with the increasing requirement of far-range detection,the time bandwidth product,which is corresponding to radar’s mean power,should be promoted in actual application.Thus,the echo signal generates the scale effect(SE)at large time bandwidth product situation,influencing the intra and inter pulse integration performance.To eliminate SE and correct RM,this paper proposes an effective algorithm,i.e.,scaled location rotation transform(ScLRT).The ScLRT can remove SE to obtain the matching pulse compression(PC)as well as correct RM to complete CI via the location rotation transform,being implemented by seeking the actual rotation angle.Compared to the traditional coherent detection algorithms,Sc LRT can address the SE problem to achieve better detection/estimation capabilities.At last,this paper gives several simulations to assess the viability of ScLRT.展开更多
Due to the complex high-temperature characteristics of hydrocarbon fuel,the research on the long-term working process of parallel channel structure under variable working conditions,especially under high heat-mass rat...Due to the complex high-temperature characteristics of hydrocarbon fuel,the research on the long-term working process of parallel channel structure under variable working conditions,especially under high heat-mass ratio,has not been systematically carried out.In this paper,the heat transfer and flow characteristics of related high temperature fuels are studied by using typical engine parallel channel structure.Through numeri⁃cal simulation and systematic experimental verification,the flow and heat transfer characteristics of parallel chan⁃nels under typical working conditions are obtained,and the effectiveness of high-precision calculation method is preliminarily established.It is known that the stable time required for hot start of regenerative cooling engine is about 50 s,and the flow resistance of parallel channel structure first increases and then decreases with the in⁃crease of equivalence ratio(The following equivalence ratio is expressed byΦ),and there is a flow resistance peak in the range ofΦ=0.5~0.8.This is mainly caused by the coupling effect of high temperature physical proper⁃ties,flow rate and pressure of fuel in parallel channels.At the same time,the cooling and heat transfer character⁃istics of parallel channels under some conditions of high heat-mass ratio are obtained,and the main factors affect⁃ing the heat transfer of parallel channels such as improving surface roughness and strengthening heat transfer are mastered.In the experiment,whenΦis less than 0.9,the phenomenon of local heat transfer enhancement and deterioration can be obviously observed,and the temperature rise of local structures exceeds 200℃,which is the risk of structural damage.Therefore,the reliability of long-term parallel channel structure under the condition of high heat-mass ratio should be fully considered in structural design.展开更多
This study systematically investigated the effects of experimental conditions,crystal phase,and microstructure on the preparation of V_(2)O_(3)for vanadium flow batteries by reducing ammonium metavanadate extracted fr...This study systematically investigated the effects of experimental conditions,crystal phase,and microstructure on the preparation of V_(2)O_(3)for vanadium flow batteries by reducing ammonium metavanadate extracted from waste catalyst.The optimized experimental conditions were determined as follows:the CO reduction temperature was set at 575℃,the reduction time was 1 hour,the CO flow rate was 50 mL/min,and furnace cooling was performed subsequently.Under these conditions,the samples obtained were predominantly composed of single-phase V_(2)O_(3).Microstructural analysis reveals tightly packed grain configurations exhibiting flake-like or block-like morphologies.Significantly,the as-synthesized V_(2)O_(3)demonstrates sufficient purity for fabricating high-performance electrolytes in all-vanadium flow batteries,showing promising electrochemical applicability.展开更多
By combining with an improved model on engraving process,a two-phase flow interior ballistic model has been proposed to accurately predict the flow and energy conversion behaviors of pyrotechnic actuators.Using comput...By combining with an improved model on engraving process,a two-phase flow interior ballistic model has been proposed to accurately predict the flow and energy conversion behaviors of pyrotechnic actuators.Using computational fluid dynamics(CFD),the two-phase flow and piston engraving characteristics of a pyrotechnic actuator are investigated.Initially,the current model was utilized to examine the intricate,multi-dimensional flow,and energy conversion characteristics of the propellant grains and combustion gas within the pyrotechnic actuator chamber.It was discovered that the combustion gas on the wall's constant transition from potential to kinetic energy,along with the combined effect of the propellant motion,are what create the pressure oscillation within the chamber.Additionally,a numerical analysis was conducted to determine the impact of various parameters on the pressure oscillation and piston motion,including pyrotechnic charge,pyrotechnic particle size,and chamber structural dimension.The findings show that decreasing the pyrotechnic charge will lower the terminal velocity,while increasing and decreasing the pyrotechnic particle size will reduce the pressure oscillation in the chamber.The pyrotechnic particle size has minimal bearing on the terminal velocity.The results of this investigation offer a trustworthy forecasting instrument for comprehending and creating pyrotechnic actuator designs.展开更多
The melt stirring in a large copper smelting oxygen bottom-blown furnace is caused by the large amount of gas movement blown in by two rows of oxygen lances.At present,the two rows of oxygen lances provide oxygen of e...The melt stirring in a large copper smelting oxygen bottom-blown furnace is caused by the large amount of gas movement blown in by two rows of oxygen lances.At present,the two rows of oxygen lances provide oxygen of equal strength,and the stirring in the central area of the melt is insufficient,which restricts the efficient progress of the smelting reaction.This study proposes a strong-weak coupling oxygen supply method and establishes an equivalent model based on a large bottom-blown furnace(LBBF)of an enterprise to simulate the bubble characteristics and flow characteristics of the molten pool.The results show that adjusting the flow ratio between the two rows of oxygen lances can create a“strong”and a“weak”coexisting source of disturbance in an LBBF.It is worth noting that when the flow rate ratio of the two rows of oxygen lances is 1.6,the peak velocity generated by the“strong”distur bance source in the molten pool increases by 18.92%,and the disturbance range increases.This method effectively strengthens the stirring in the central area of the molten pool,improves smelting efficiency,and does not produce harmful melt splashes.It provides important guidance for optimizing production practice.展开更多
Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive r...Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive research on the effects of W-D cycles,the coupling influence of flow rates and W-D cycles on gypsum rocks remains poorly understood.This study investigates the mechanical behavior and deterioration mechanisms of gypsum rocks subjected to varying W-D cycles and flow rate conditions.Axial compression tests,along with nuclear magnetic resonance(NMR)techniques,were employed to analyze the stress-strain response and microstructural changes.Based on the disturbed state concept(DSC)theory,a W-D deterioration model and a DSC-based constitutive model were developed to describe the degradation trends and mechanical responses of gypsum rocks under different conditions.The results demonstrate that key mechanical indices,elastic modulus,cohesion,uniaxial compressive strength(UCS),and internal friction angle,exhibit logarithmic declines with increasing W-D cycles,with higher flow rates accelerating the deterioration process.The theoretical models accurately capture the nonlinear compaction behavior,peak stress,and post-peak response of gypsum specimens.This study provides valuable insights for predicting the mechanical behavior of gypsum rocks and improving the stability assessments of underground structures under complex environmental conditions.展开更多
The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personn...The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personnel from firing artillery within the cab.To investigate the overpressure characteristics of the FFICC,a foreign trade equipment model was used as the research object,and a numerical model was established to analyze the propagation of muzzle blast from the muzzle to the interior of the crew compartment under extreme firing condition.For comparative verification,the muzzle blast experiment included overpressure data from both the flow field outside the crew compartment(FFOCC)and the FFICC,as well as the acceleration data of the crew compartment structure(Str-CC).The research findings demonstrate that the overpressure-time curves of the FFICC exhibit multi-peak characteristics,while the pressure wave shows no significant discontinuity.The enclosed nature of the cab hinders the dissipation of pressure wave energy within the FFICC,leading to sustained high-amplitude overpressure.The frameskin structure helps attenuate the impact of muzzle blast on the FFICC.Conversely,local high overpressure caused by the convex or concave features of the cab's exterior significantly amplifies the overpressure amplitude within the FFICC.展开更多
Lateral migration of fault activity in Weihe basin is a popular phenomenon and its characteristics are also typical. Taking the activity migrations of Wangshun Mountain piedmont fault toward Lishan piedmont fault and ...Lateral migration of fault activity in Weihe basin is a popular phenomenon and its characteristics are also typical. Taking the activity migrations of Wangshun Mountain piedmont fault toward Lishan piedmont fault and Weinan platform front fault, Dabaopi-Niujiaojian fault toward Shenyusi-Xiaojiazhai fault, among a serial of NE-trending faults from Baoji city to Jingyang County as examples, their migration time and process are analyzed and discussed in the present paper. It is useful for further understanding the structure development and physiognomy evolution history of Weihe basin.展开更多
Based on arbitrarily wide-angle wave equations,a reverse-time propagation scheme is developed by substituting the partial derivatives of depth and time with central differences. The partial derivative of horizontal di...Based on arbitrarily wide-angle wave equations,a reverse-time propagation scheme is developed by substituting the partial derivatives of depth and time with central differences. The partial derivative of horizontal direction is replaced with high order difference. The imaging condition is computed by solving the eikonal equations. On the basis of above techniques,a prestack reverse-time depth migration algorithm is developed. The processing exam-ples of synthetic data show that the method can remove unwanted internal reflections and decrease the migration noise. The method also has the advantage of fidelity and is applicable of dip angle reflector imaging.展开更多
OBJECTIVE To investigate the role and mechanism of G protein-coupled receptor kinase 2(GRK2)involving in hepatocel ular carcinoma(HCC)progression.METHODS Cel Counting Kit 8 and tumor colony formation assay were design...OBJECTIVE To investigate the role and mechanism of G protein-coupled receptor kinase 2(GRK2)involving in hepatocel ular carcinoma(HCC)progression.METHODS Cel Counting Kit 8 and tumor colony formation assay were designed to detect HCC cell proliferation,wound healing assay was to detect HCC migration.The correlation between GRK2 and early growth response-1(EGR1)were detected by RT-PCR and real-time PCR assays.Co-immunoprecipitation and Western blot assay were adopted to detect the relationship between GRK2and insulin-like growth factor 1 receptor(IGF-1R)signaling pathway.RESULTS In this study we find that GRK2plays an inhibition role in IGF1-induced HCC cell proliferation and migration.Overexpression of GRK2 causes a decrease in EGR1 expression,while knockdown of GRK2 leads to the dramatically increase in EGR1 expression in the treatment of IGF1.Through co-immunoprecipitation and Western blot assay,we confirm that GRK2can interact with IGF-1R and inhibiting IGF1-induced activation of IGF1R signaling pathway.Silencing EGR1attenuates GRK2 overexpression-caused inhibition of cell proliferation,tumor colony number and migrationactivity,while overexpressing of EGR1 restores the antiproliferative and migratory effect by GRK2 overexpression in HCCLM3 cells.CONCLUSION Taken together,these results suggest that GRK2 may inhibit IGF1-induced HCC cell growth and migration through down-regulation of EGR1 and indicate that enforced GRK2 may offer a potential therapeutic approach against HCC.展开更多
基金supported by the National Natural Science Foundation of China(62101099)the Chinese Postdoctoral Science Foundation(2021M690558,2022T150100,2018M633352,2019T120825)+3 种基金the Young Elite Scientist Sponsorship Program(YESS20200082)the Aeronautical Science Foundation of China(2022Z017080001)the Open Foundation of Science and Technology on Electronic Information Control Laboratorythe Natural Science Foundation of Sichuan Province(2023NSFSC1386)。
文摘The detection of hypersonic targets usually confronts range migration(RM)issue before coherent integration(CI).The traditional methods aiming at correcting RM to obtain CI mainly considers the narrow-band radar condition.However,with the increasing requirement of far-range detection,the time bandwidth product,which is corresponding to radar’s mean power,should be promoted in actual application.Thus,the echo signal generates the scale effect(SE)at large time bandwidth product situation,influencing the intra and inter pulse integration performance.To eliminate SE and correct RM,this paper proposes an effective algorithm,i.e.,scaled location rotation transform(ScLRT).The ScLRT can remove SE to obtain the matching pulse compression(PC)as well as correct RM to complete CI via the location rotation transform,being implemented by seeking the actual rotation angle.Compared to the traditional coherent detection algorithms,Sc LRT can address the SE problem to achieve better detection/estimation capabilities.At last,this paper gives several simulations to assess the viability of ScLRT.
文摘Due to the complex high-temperature characteristics of hydrocarbon fuel,the research on the long-term working process of parallel channel structure under variable working conditions,especially under high heat-mass ratio,has not been systematically carried out.In this paper,the heat transfer and flow characteristics of related high temperature fuels are studied by using typical engine parallel channel structure.Through numeri⁃cal simulation and systematic experimental verification,the flow and heat transfer characteristics of parallel chan⁃nels under typical working conditions are obtained,and the effectiveness of high-precision calculation method is preliminarily established.It is known that the stable time required for hot start of regenerative cooling engine is about 50 s,and the flow resistance of parallel channel structure first increases and then decreases with the in⁃crease of equivalence ratio(The following equivalence ratio is expressed byΦ),and there is a flow resistance peak in the range ofΦ=0.5~0.8.This is mainly caused by the coupling effect of high temperature physical proper⁃ties,flow rate and pressure of fuel in parallel channels.At the same time,the cooling and heat transfer character⁃istics of parallel channels under some conditions of high heat-mass ratio are obtained,and the main factors affect⁃ing the heat transfer of parallel channels such as improving surface roughness and strengthening heat transfer are mastered.In the experiment,whenΦis less than 0.9,the phenomenon of local heat transfer enhancement and deterioration can be obviously observed,and the temperature rise of local structures exceeds 200℃,which is the risk of structural damage.Therefore,the reliability of long-term parallel channel structure under the condition of high heat-mass ratio should be fully considered in structural design.
文摘This study systematically investigated the effects of experimental conditions,crystal phase,and microstructure on the preparation of V_(2)O_(3)for vanadium flow batteries by reducing ammonium metavanadate extracted from waste catalyst.The optimized experimental conditions were determined as follows:the CO reduction temperature was set at 575℃,the reduction time was 1 hour,the CO flow rate was 50 mL/min,and furnace cooling was performed subsequently.Under these conditions,the samples obtained were predominantly composed of single-phase V_(2)O_(3).Microstructural analysis reveals tightly packed grain configurations exhibiting flake-like or block-like morphologies.Significantly,the as-synthesized V_(2)O_(3)demonstrates sufficient purity for fabricating high-performance electrolytes in all-vanadium flow batteries,showing promising electrochemical applicability.
基金supported by the National Natural Science Foundation of China(Grant No.11972194).
文摘By combining with an improved model on engraving process,a two-phase flow interior ballistic model has been proposed to accurately predict the flow and energy conversion behaviors of pyrotechnic actuators.Using computational fluid dynamics(CFD),the two-phase flow and piston engraving characteristics of a pyrotechnic actuator are investigated.Initially,the current model was utilized to examine the intricate,multi-dimensional flow,and energy conversion characteristics of the propellant grains and combustion gas within the pyrotechnic actuator chamber.It was discovered that the combustion gas on the wall's constant transition from potential to kinetic energy,along with the combined effect of the propellant motion,are what create the pressure oscillation within the chamber.Additionally,a numerical analysis was conducted to determine the impact of various parameters on the pressure oscillation and piston motion,including pyrotechnic charge,pyrotechnic particle size,and chamber structural dimension.The findings show that decreasing the pyrotechnic charge will lower the terminal velocity,while increasing and decreasing the pyrotechnic particle size will reduce the pressure oscillation in the chamber.The pyrotechnic particle size has minimal bearing on the terminal velocity.The results of this investigation offer a trustworthy forecasting instrument for comprehending and creating pyrotechnic actuator designs.
基金Project(2022YFC3901501)supported by the National Key R&D Program of ChinaProject(U20A20273)supported by the National Natural Science Foundation of China+1 种基金Project(2022JJ10078)supported by the Natural Science Foundation for Distinguished Young Scholars of Hunan Province,ChinaProject(2021RC3005)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘The melt stirring in a large copper smelting oxygen bottom-blown furnace is caused by the large amount of gas movement blown in by two rows of oxygen lances.At present,the two rows of oxygen lances provide oxygen of equal strength,and the stirring in the central area of the melt is insufficient,which restricts the efficient progress of the smelting reaction.This study proposes a strong-weak coupling oxygen supply method and establishes an equivalent model based on a large bottom-blown furnace(LBBF)of an enterprise to simulate the bubble characteristics and flow characteristics of the molten pool.The results show that adjusting the flow ratio between the two rows of oxygen lances can create a“strong”and a“weak”coexisting source of disturbance in an LBBF.It is worth noting that when the flow rate ratio of the two rows of oxygen lances is 1.6,the peak velocity generated by the“strong”distur bance source in the molten pool increases by 18.92%,and the disturbance range increases.This method effectively strengthens the stirring in the central area of the molten pool,improves smelting efficiency,and does not produce harmful melt splashes.It provides important guidance for optimizing production practice.
基金Projects(52378392,52478390)supported by the National Natural Science Foundation of ChinaProject(2024J08213)supported by the Natural Science Foundation of Fujian Province,China+1 种基金Project(00387088)supported by the“Foal Eagle Program”Youth Top-notch Talent Project of Fujian Province,ChinaProject(GY-Z23072)supported by the Scientific Research Foundation of Fujian University of Technology,China。
文摘Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive research on the effects of W-D cycles,the coupling influence of flow rates and W-D cycles on gypsum rocks remains poorly understood.This study investigates the mechanical behavior and deterioration mechanisms of gypsum rocks subjected to varying W-D cycles and flow rate conditions.Axial compression tests,along with nuclear magnetic resonance(NMR)techniques,were employed to analyze the stress-strain response and microstructural changes.Based on the disturbed state concept(DSC)theory,a W-D deterioration model and a DSC-based constitutive model were developed to describe the degradation trends and mechanical responses of gypsum rocks under different conditions.The results demonstrate that key mechanical indices,elastic modulus,cohesion,uniaxial compressive strength(UCS),and internal friction angle,exhibit logarithmic declines with increasing W-D cycles,with higher flow rates accelerating the deterioration process.The theoretical models accurately capture the nonlinear compaction behavior,peak stress,and post-peak response of gypsum specimens.This study provides valuable insights for predicting the mechanical behavior of gypsum rocks and improving the stability assessments of underground structures under complex environmental conditions.
基金supported by the National Natural Science Foundation of China(Grant No.U2341269)。
文摘The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personnel from firing artillery within the cab.To investigate the overpressure characteristics of the FFICC,a foreign trade equipment model was used as the research object,and a numerical model was established to analyze the propagation of muzzle blast from the muzzle to the interior of the crew compartment under extreme firing condition.For comparative verification,the muzzle blast experiment included overpressure data from both the flow field outside the crew compartment(FFOCC)and the FFICC,as well as the acceleration data of the crew compartment structure(Str-CC).The research findings demonstrate that the overpressure-time curves of the FFICC exhibit multi-peak characteristics,while the pressure wave shows no significant discontinuity.The enclosed nature of the cab hinders the dissipation of pressure wave energy within the FFICC,leading to sustained high-amplitude overpressure.The frameskin structure helps attenuate the impact of muzzle blast on the FFICC.Conversely,local high overpressure caused by the convex or concave features of the cab's exterior significantly amplifies the overpressure amplitude within the FFICC.
基金Chinese Joint Seismological Science Foundation (100120) and State Key Basic Research Development and Programming Project of China (G199804070102).
文摘Lateral migration of fault activity in Weihe basin is a popular phenomenon and its characteristics are also typical. Taking the activity migrations of Wangshun Mountain piedmont fault toward Lishan piedmont fault and Weinan platform front fault, Dabaopi-Niujiaojian fault toward Shenyusi-Xiaojiazhai fault, among a serial of NE-trending faults from Baoji city to Jingyang County as examples, their migration time and process are analyzed and discussed in the present paper. It is useful for further understanding the structure development and physiognomy evolution history of Weihe basin.
文摘Based on arbitrarily wide-angle wave equations,a reverse-time propagation scheme is developed by substituting the partial derivatives of depth and time with central differences. The partial derivative of horizontal direction is replaced with high order difference. The imaging condition is computed by solving the eikonal equations. On the basis of above techniques,a prestack reverse-time depth migration algorithm is developed. The processing exam-ples of synthetic data show that the method can remove unwanted internal reflections and decrease the migration noise. The method also has the advantage of fidelity and is applicable of dip angle reflector imaging.
基金The project supported by National Natural Science Foundation of China(81502123,81330081,81202596)Natural Science Foundation of Anhui Province(1308085QH130)+3 种基金Anhui Province Natural Science Foundation in University(KJ2014A119)Grants for Scientific Research of BSKY from Anhui Medical University(XJ201212)Specialized Research Fund for the Doctoral Program of Higher Education(20113420120006,20123420110003)Program for Tackling Key Problems in Science and Technology by Anhui Province(1301042098)
文摘OBJECTIVE To investigate the role and mechanism of G protein-coupled receptor kinase 2(GRK2)involving in hepatocel ular carcinoma(HCC)progression.METHODS Cel Counting Kit 8 and tumor colony formation assay were designed to detect HCC cell proliferation,wound healing assay was to detect HCC migration.The correlation between GRK2 and early growth response-1(EGR1)were detected by RT-PCR and real-time PCR assays.Co-immunoprecipitation and Western blot assay were adopted to detect the relationship between GRK2and insulin-like growth factor 1 receptor(IGF-1R)signaling pathway.RESULTS In this study we find that GRK2plays an inhibition role in IGF1-induced HCC cell proliferation and migration.Overexpression of GRK2 causes a decrease in EGR1 expression,while knockdown of GRK2 leads to the dramatically increase in EGR1 expression in the treatment of IGF1.Through co-immunoprecipitation and Western blot assay,we confirm that GRK2can interact with IGF-1R and inhibiting IGF1-induced activation of IGF1R signaling pathway.Silencing EGR1attenuates GRK2 overexpression-caused inhibition of cell proliferation,tumor colony number and migrationactivity,while overexpressing of EGR1 restores the antiproliferative and migratory effect by GRK2 overexpression in HCCLM3 cells.CONCLUSION Taken together,these results suggest that GRK2 may inhibit IGF1-induced HCC cell growth and migration through down-regulation of EGR1 and indicate that enforced GRK2 may offer a potential therapeutic approach against HCC.
