Rectifying circuit,as a crucial component for converting alternating current into direct current,plays a pivotal role in energy harvesting microsystems.Traditional silicon-based or germanium-based rectifier diodes hin...Rectifying circuit,as a crucial component for converting alternating current into direct current,plays a pivotal role in energy harvesting microsystems.Traditional silicon-based or germanium-based rectifier diodes hinder system integration due to their specific manufacturing processes.Conversely,metal oxide diodes,with their simple fabrication techniques,offer advantages for system integration.The oxygen vacancy defect of oxide semiconductor will greatly affect the electrical performance of the device,so the performance of the diode can be effectively controlled by adjusting the oxygen vacancy concentration.This study centers on optimizing the performance of diodes by modulating the oxygen vacancy concentration within InGaZnO films through control of oxygen flows during the sputtering process.Experimental results demonstrate that the diode exhibits a forward current density of 43.82 A·cm^(−2),with a rectification ratio of 6.94×10^(4),efficiently rectifying input sine signals with 1 kHz frequency and 5 V magnitude.These results demonstrate its potential in energy conversion and management.By adjusting the oxygen vacancy,a methodology is provided for optimizing the performance of rectifying diodes.展开更多
Surface engineering plays a crucial role in improving the performance of high energy materials,and polydopamine(PDA)is widely used in the field of energetic materials for surface modification and functionalization.In ...Surface engineering plays a crucial role in improving the performance of high energy materials,and polydopamine(PDA)is widely used in the field of energetic materials for surface modification and functionalization.In order to obtain high-quality HMX@PDA-based PBX explosives with high sphericity and a narrow particle size distribution,composite microspheres were prepared using co-axial droplet microfluidic technology.The formation mechanism,thermal behavior,mechanical sensitivity,electrostatic spark sensitivity,compressive strength,and combustion performance of the microspheres were investigated.The results show that PDA can effectively enhance the interfacial interaction between the explosive particles and the binder under the synergistic effect of chemical bonds and the physical"mechanical interlocking"structure.Interface reinforcement causes the thermal decomposition temperature of the sample microspheres to move to a higher temperature,with the sensitivity to impact,friction,and electrostatic sparks(for S-1)increasing by 12.5%,31.3%,and 81.5%respectively,and the compressive strength also increased by 30.7%,effectively enhancing the safety performance of the microspheres.Therefore,this study provides an effective and universal strategy for preparing high-quality functional explosives,and also provides some reference for the safe use of energetic materials in practical applications.展开更多
To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying ...To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.展开更多
To investigate the overall performance of reverse energy bypass scramjet,firstly a variable spe⁃cific heat method combined with a chemical balance calculation module for combustion products were used to es⁃tablish a b...To investigate the overall performance of reverse energy bypass scramjet,firstly a variable spe⁃cific heat method combined with a chemical balance calculation module for combustion products were used to es⁃tablish a benchmark scramjet performance evaluation model.Based on the test data of typical flying point of Mach 7 with the altitude of 29 km,the reliability of the model was verified.The deviations of parameters such as the to⁃tal pressure loss of combustor between the model and the test data were analyzed.Furtherly,an analytical method for post-combustion magnetohydrodynamic power generation was established;by embedding the above method into the overall performance evaluation model,performance prediction considering the power generation effect was realized.Finally,based on the above model,variety regulations of the inlet and the outlet parameters of the power generation channel and performance parameters including the engine specific impulse and the unit thrust under different enthalpy extraction ratios and load factors were analyzed.It could be concluded that the model can reliably predict the variations of key parameters.As the value of the load factor increases,the value of the conduc⁃tivity required to reach the specified enthalpy extraction ratio first decreases and then increases,which is approxi⁃mately parabolic.In order to reduce the demand for the gas conductivity for MHD power generation,the load fac⁃tor should be around 0.5.When the load factor is 0.4 and the magnetic induction intensity is 2.5 T,if the enthalpy extraction ratio reaches 0.5%,the engine specific impulse performance reduces about 3.58%.展开更多
A low-cost 1D cobalt-based coordination polymer(CP)[Co(BGPD)(DMSO)_(2)(H_(2)O)_(2)](Co-BD;H2BGPD=N,N'-bis(glycinyl)pyromellitic diimide;DMSO=dimethyl sulfoxide)was synthesized by a simple method,and its crystal st...A low-cost 1D cobalt-based coordination polymer(CP)[Co(BGPD)(DMSO)_(2)(H_(2)O)_(2)](Co-BD;H2BGPD=N,N'-bis(glycinyl)pyromellitic diimide;DMSO=dimethyl sulfoxide)was synthesized by a simple method,and its crystal structure was characterized.In a three-electrode system,Co-BD,as the electrode material for supercapacitors,achieved a specific capacitance of 830 F·g^(-1)at 1 A·g^(-1),equivalent to a specific capacity of 116.4 mAh·g^(-1),and exhibited high-rate capability,reaching 212 F·g^(-1)at 20 A·g^(-1).Impressively,Co-BD||rGO(reduced graphene oxide),representing an asymmetrical supercapacitor,owns a higher energy density of 14.2 Wh·kg^(-1)at 0.80 kW·kg^(-1),and an excellent cycle performance(After 4000 cycles at 1 A·g^(-1),the capacitance retention was up to 94%).CCDC:2418872.展开更多
著者:张蔚出版社:劳特利奇(Routledge)出版社出版时间:2024年12月此英文专著是国际权威劳特利奇出版社当代中国系列(Routledge Contemporary China Series)的最新一本英文专著,也是劳特利奇出版社戏剧和表演研究系列(Theatre&Perfor...著者:张蔚出版社:劳特利奇(Routledge)出版社出版时间:2024年12月此英文专著是国际权威劳特利奇出版社当代中国系列(Routledge Contemporary China Series)的最新一本英文专著,也是劳特利奇出版社戏剧和表演研究系列(Theatre&Performance Studies)的最新著作。全书共七章,从文化的属性,历史的渊源,人种的迁移等视角切人,探讨比较了地缘关系、表演形态中的中国北方汉族与少数民族、中国与东亚、东南亚和南亚在宗教信仰、文化习俗方面的关联、传播和交融,体现在动律体态上的特点及其对表演形式与流派的变革性影响。展开更多
The purpose of this experiment was to investigate the effect and mechanism of quercetin on reproductive performance in perinatal sows.According to the similar principle of parity and body weight,24 perinatal sows were...The purpose of this experiment was to investigate the effect and mechanism of quercetin on reproductive performance in perinatal sows.According to the similar principle of parity and body weight,24 perinatal sows were randomly divided into four treatments with six replicates,including normal control and three treatments fed by a basal diet supplemented with 0,0.025%,0.050%,and 0.075%quercetin,respectively.The feeding trial was conducted from 100 days of gestation to 28 days post-partum.Reproductive performance,colostrum composition,serum indexes of antioxidation,inflammation,hormones,and the diversity and relative abundance of fecal microflora were determined in perinatal sows.Compared with the control,quercetin significantly reduced the rate of constipation,serum content of malondialdehyde(MDA),prolactin(PRL),and progesterone(PROG),and significantly increased the content of serum estradiol(E2)and insulin-like growth factor-1(IGF-1)in colostrum of perinatal sows(P<0.05).Meanwhile,0.025%quercetin significantly increased glutathione(GSH)content in serum(P<0.05),0.050%quercetin significantly reduced the rate of backfat loss(P<0.05),and 0.075%quercetin significantly increased immunoglobulin M(IgM)content in colostrum of perinatal sows(P<0.05).In addition,0.050%and 0.075%quercetin significantly shortened estrus interval(P<0.05)and significantly increased the content of IgA and IgG in colostrum(P<0.05)and dopamine(DA)content in serum of perinatal sows(P<0.05).Quercetin significantly decreased the content of nitric oxide(NO),IL-1β,IL-6,TNF-α,and MCP-1 in serum(P<0.05)and significantly improved microflora abundance and diversity in feces of perinatal sows(P<0.05).In conclusion,dietary supplementation of quercetin reduced oxidative stress and inflammatory responses and regulated intestinal microflora in perinatal sows,thus improved reproductive performance in perinatal sows.Under this experimental condition,the optimal supplementation with dietary quercetin was 0.075%in perinatal sows.展开更多
When the protective and protected systems are detached,the former can be allowed to absorb the kinetic energy of the impacting projectile through large deformation without considering the back face signature of the la...When the protective and protected systems are detached,the former can be allowed to absorb the kinetic energy of the impacting projectile through large deformation without considering the back face signature of the latter.This paper presents a novel double-face knitted fabric(DFKF)designed for this very impacting scenario.Shooting tests equipped with high-speed camera were used to characterize the ballistic performance with the impact velocities ranging from 100 m/s to 450 m/s.The results showed that the ballistic limits(V_(bl))of DFKF are approximately triple and double that of its counterpart UD and plain fabrics,respectively.For mass-normalized metrics,the specific energy absorption(SEA)is 250%and 350%greater than the UD and plain fabrics at their corresponding V_(bl)s.The quasi-static tests showed that the DFKF displayed greater resilience,crease recovery properties,and flexibility,which also made it an especially better candidate than UD and plain weaves for the design of umbrella surface cloth.It was also found that DFKF is dependent on yarn count and the incorporation of spandex.A prototype anti-ballistic umbrella is manufactured using DFKF made of 200D multi-filament yarn.The ballistic performance is also sensitive to the impact site when the umbrella is subjected to impact.展开更多
Detonation performance is crucial for evaluating the power of high explosives(HEs),and the equation of state(EOS)that accurately describes the high-temperature,high-pressure,and high-temperature,medium-pressure states...Detonation performance is crucial for evaluating the power of high explosives(HEs),and the equation of state(EOS)that accurately describes the high-temperature,high-pressure,and high-temperature,medium-pressure states of detonation products is key to assessing the damage efficiency of these energetic materials.This article examines the limitations of the VLW EOS in representing the thermodynamic states of explosive detonation gas products under high-temperature and medium-to high-pressure conditions.A new gas EOS for detonation products,called VHL(Virial-Han-Long),is proposed.The accuracy of VHL in describing gas states under high-temperature and medium-to high-pressure conditions is verified,and its performance in evaluating explosive detonation and working capabilities is explored.The results demonstrate that VHL exhibits high precision in calculating detonation performance.Subsequently,the detonation performance of three new HEs(ICM-101,ONC,and TNAZ)was calculated and compared to traditional HEs(TATB,CL-20,and HMX).The results indicate that ONC has superior detonation performance compared to the other explosives,while ICM-101 shows a detonation velocity similar to CL-20 but with slightly lower detonation pressure.The detonation characteristics of TNAZ are comparable to those of the standard HE HMX.From the perspective of products,considering the comprehensive work performance(mechanical work and detonation heat),both ONC and ICM-101demonstrate relatively superior performance.展开更多
Following the fundamental characteristics of the porosity windbreak,this study suggests a new numerical investigation method for the wind field of the windbreak based on the porous medium physical model.This method ca...Following the fundamental characteristics of the porosity windbreak,this study suggests a new numerical investigation method for the wind field of the windbreak based on the porous medium physical model.This method can transform the reasonable matching problem of the porosity and windproof performance of the windbreak into a study of the relationship between the resistance coefficient of the porous medium and the aerodynamic load of the train.This study examines the influence of the hole type on the wind field behind the porosity windbreak.Then,the relationship between the resistance coefficient of the porous medium,the porosity of the windbreak,and the aerodynamic loads of the train is investigated.The results show that the porous media physical model can be used instead of the windbreak geometry to study the windbreak-train aerodynamic performance,and the process of using this method is suggested.展开更多
Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current r...Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current research on the anti-penetration of aramid fabrics mostly focuses unilaterally on the structure and performance of aramid fabrics or the shape and size of projectiles,with fewer studies on the coupled effect of both on ballistic performance.This study analyzes how the coupling relationship(or size effect)between the projectile and fiber bundle dimensions affects the fabric ballistic performance from a mesoscopic scale perspective.Taking plain weave aramid fabric as the research object,considering different diameter projectiles,through a large number of ballistic impact tests and numerical simulations,parameters such as ballistic limit velocity,average energy absorption of fabric,and specific energy absorption ratio(average energy absorption of fabric divided by projectile cross-sectional area)are obtained for ballistic performance analysis.The influence law of projectile size on the ballistic performance of high-performance fabrics is as follows:The relative range of fitted ballistic limit velocity at different target positions gradually decreases and then stabilizes as the projectile diameter increases,indicating that the fabric structure effect gradually disappears at a projectile diameter of 12 mm;The average ballistic limit velocity at three impact positions,P1,P2,and P3,provides the corresponding ballistic limit velocity for 1000D aramid fabric,which increases with projectile diameter but the rate of increase slows down at an inflection point,which in this study occurs where the fabric structure effect nearly disappears at a projectile diameter of 12 mm;The energy absorption ratio increases and then decreases as the projectile diameter increases from 4 mm to 20 mm,reaching a peak at the diameter of 12 mm due to the gradual disappearance of the fabric structural effect.The projectile diameter of 12 mm corresponds to the coupling size of 11.159,which provides a size design reference for the macroscopic-based continuum models of aramid plain weave fabrics.展开更多
The present study introduces a screw-pressing charging method to tackle deficiencies in automation and charge uniformity during the melt-casting of polymer-based energetic materials.To ensure the safety of the experim...The present study introduces a screw-pressing charging method to tackle deficiencies in automation and charge uniformity during the melt-casting of polymer-based energetic materials.To ensure the safety of the experiments,this study used inert materials with similar physical properties to partially substitute for the actual energetic components in the preparation of simulant materials.By thoroughly analyzing slurry physical properties,a simulation framework and an extensive performance evaluation method were developed.Such tools guide the design of the structure and configuration of process parameters.Results demonstrate that employing the Pin element significantly enhances radial mixing within the screw,minimizes temperature variations in the slurry,and improves both efficiency and safety in the mixing process.Further,adjustments such as widening the cone angle of the barrel,modifying the solid content of the slurry,and varying the speed of the screw can optimize the mechanical and thermal coupling in the flow field.These adjustments promote higher-quality slurry and create a safer production environment for the extrusion process.展开更多
Because of an unfortunate mistake by authors,the Project(5227010679)of Foundation item was wrong.The corrected Project is shown as follows:Project(52271073).
Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced in...Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of boron.The results indicated that the PDA coating formed a fishing net structure on the surface of boron particles.The heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw boron.Specifically,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw boron.Simultaneously,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were evaluated.It was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,respectively.The peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@AP.Therefore,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.展开更多
This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance system...This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance systems of missiles is challenging.As our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy.The global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional PPF.Then,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities.Meanwhile,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify disturbances.The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots.展开更多
The design of mini-missiles(MMs)presents several novel challenges.The stringent mission requirement to reach a target with a certain precision imposes a high guidance precision.The miniaturization of the size of MMs m...The design of mini-missiles(MMs)presents several novel challenges.The stringent mission requirement to reach a target with a certain precision imposes a high guidance precision.The miniaturization of the size of MMs makes the design of the guidance,navigation,and control(GNC)have a larger-thanbefore impact on the main-body design(shape,motor,and layout design)and its design objective,i.e.,flight performance.Pursuing a trade-off between flight performance and guidance precision,all the relevant interactions have to be accounted for in the design of the main body and the GNC system.Herein,a multi-objective and multidisciplinary design optimization(MDO)is proposed.Disciplines pertinent to motor,aerodynamics,layout,trajectory,flight dynamics,control,and guidance are included in the proposed MDO framework.The optimization problem seeks to maximize the range and minimize the guidance error.The problem is solved by using the nondominated sorting genetic algorithm II.An optimum design that balances a longer range with a smaller guidance error is obtained.Finally,lessons learned about the design of the MM and insights into the trade-off between flight performance and guidance precision are given by comparing the optimum design to a design provided by the traditional approach.展开更多
Carbonized melamine foam has been recognized as a promising material for microwave absorption due to its exceptional thermal stability,lightweight,and remarkable dielectric properties.In this study,we investigated the...Carbonized melamine foam has been recognized as a promising material for microwave absorption due to its exceptional thermal stability,lightweight,and remarkable dielectric properties.In this study,we investigated the impact of nitric acid oxidation on the surface of carbonized melamine foam and its microwave absorption properties.The treated foam exhibits optimal reflection loss of−21.51 dB at 13.20 GHz,with an effective absorption bandwidth of 7.04 GHz.The enhanced absorption properties are primarily attributed to the strengthened dielectric loss,improved impedance matching,and increased polarization losses resulting from the oxidized surfaces.This research demonstrates a promising new approach for research into surface treatments to improve the performances of microwave absorbers.展开更多
An adaptive control approach is presented in this paper for tracking desired trajectories in interactive manipulators. The controller design incorporates prescribed performance functions (PPFs) to improve dynamic perf...An adaptive control approach is presented in this paper for tracking desired trajectories in interactive manipulators. The controller design incorporates prescribed performance functions (PPFs) to improve dynamic performance. Notably, the performance of the output error is confined in an envelope characterized by exponential convergence, leading to convergence to zero. This feature ensures a prompt response from admittance control and establishes a reliable safety framework for interactions. Simulation results provide practical insights,demonstrating the viability of the control scheme proposed in this paper.展开更多
Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology...Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.展开更多
In this manuscript,the neat epoxy(EP)and functionalized Fe_(3)O_(4)(G-Fe_(3)O_(4))reinforced epoxy(G-Fe_(3)O_(4)/EP)coatings were cured under different temperatures,and the effect of the low curing temperature on the ...In this manuscript,the neat epoxy(EP)and functionalized Fe_(3)O_(4)(G-Fe_(3)O_(4))reinforced epoxy(G-Fe_(3)O_(4)/EP)coatings were cured under different temperatures,and the effect of the low curing temperature on the anticorrosion performance was investigated.The experimental results show that the epoxy-amine ring-open addition reaction mainly exists in the curing process,and the activation energies of the reaction for the two coatings are 55.84 and 53.29 kJ/mol,respectively.For the coatings cured at the low temperature,almost no pores could be detected on the fracture surface,but the presentence of the rough regions reflects the poor curing state.As compared with the samples cured at the high temperature,the anticorrosion performance of the coatings with the low curing temperature is worse,and the decrease rate of the anticorrosion performance is slower,because of the poor curing state and low adhesion obtained at the low temperature.展开更多
文摘Rectifying circuit,as a crucial component for converting alternating current into direct current,plays a pivotal role in energy harvesting microsystems.Traditional silicon-based or germanium-based rectifier diodes hinder system integration due to their specific manufacturing processes.Conversely,metal oxide diodes,with their simple fabrication techniques,offer advantages for system integration.The oxygen vacancy defect of oxide semiconductor will greatly affect the electrical performance of the device,so the performance of the diode can be effectively controlled by adjusting the oxygen vacancy concentration.This study centers on optimizing the performance of diodes by modulating the oxygen vacancy concentration within InGaZnO films through control of oxygen flows during the sputtering process.Experimental results demonstrate that the diode exhibits a forward current density of 43.82 A·cm^(−2),with a rectification ratio of 6.94×10^(4),efficiently rectifying input sine signals with 1 kHz frequency and 5 V magnitude.These results demonstrate its potential in energy conversion and management.By adjusting the oxygen vacancy,a methodology is provided for optimizing the performance of rectifying diodes.
基金supported by the National Natural Science Foundation of China(Grant No.22005275).
文摘Surface engineering plays a crucial role in improving the performance of high energy materials,and polydopamine(PDA)is widely used in the field of energetic materials for surface modification and functionalization.In order to obtain high-quality HMX@PDA-based PBX explosives with high sphericity and a narrow particle size distribution,composite microspheres were prepared using co-axial droplet microfluidic technology.The formation mechanism,thermal behavior,mechanical sensitivity,electrostatic spark sensitivity,compressive strength,and combustion performance of the microspheres were investigated.The results show that PDA can effectively enhance the interfacial interaction between the explosive particles and the binder under the synergistic effect of chemical bonds and the physical"mechanical interlocking"structure.Interface reinforcement causes the thermal decomposition temperature of the sample microspheres to move to a higher temperature,with the sensitivity to impact,friction,and electrostatic sparks(for S-1)increasing by 12.5%,31.3%,and 81.5%respectively,and the compressive strength also increased by 30.7%,effectively enhancing the safety performance of the microspheres.Therefore,this study provides an effective and universal strategy for preparing high-quality functional explosives,and also provides some reference for the safe use of energetic materials in practical applications.
基金National Natural Science Foundation of China(No.22275150)。
文摘To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.
文摘To investigate the overall performance of reverse energy bypass scramjet,firstly a variable spe⁃cific heat method combined with a chemical balance calculation module for combustion products were used to es⁃tablish a benchmark scramjet performance evaluation model.Based on the test data of typical flying point of Mach 7 with the altitude of 29 km,the reliability of the model was verified.The deviations of parameters such as the to⁃tal pressure loss of combustor between the model and the test data were analyzed.Furtherly,an analytical method for post-combustion magnetohydrodynamic power generation was established;by embedding the above method into the overall performance evaluation model,performance prediction considering the power generation effect was realized.Finally,based on the above model,variety regulations of the inlet and the outlet parameters of the power generation channel and performance parameters including the engine specific impulse and the unit thrust under different enthalpy extraction ratios and load factors were analyzed.It could be concluded that the model can reliably predict the variations of key parameters.As the value of the load factor increases,the value of the conduc⁃tivity required to reach the specified enthalpy extraction ratio first decreases and then increases,which is approxi⁃mately parabolic.In order to reduce the demand for the gas conductivity for MHD power generation,the load fac⁃tor should be around 0.5.When the load factor is 0.4 and the magnetic induction intensity is 2.5 T,if the enthalpy extraction ratio reaches 0.5%,the engine specific impulse performance reduces about 3.58%.
文摘A low-cost 1D cobalt-based coordination polymer(CP)[Co(BGPD)(DMSO)_(2)(H_(2)O)_(2)](Co-BD;H2BGPD=N,N'-bis(glycinyl)pyromellitic diimide;DMSO=dimethyl sulfoxide)was synthesized by a simple method,and its crystal structure was characterized.In a three-electrode system,Co-BD,as the electrode material for supercapacitors,achieved a specific capacitance of 830 F·g^(-1)at 1 A·g^(-1),equivalent to a specific capacity of 116.4 mAh·g^(-1),and exhibited high-rate capability,reaching 212 F·g^(-1)at 20 A·g^(-1).Impressively,Co-BD||rGO(reduced graphene oxide),representing an asymmetrical supercapacitor,owns a higher energy density of 14.2 Wh·kg^(-1)at 0.80 kW·kg^(-1),and an excellent cycle performance(After 4000 cycles at 1 A·g^(-1),the capacitance retention was up to 94%).CCDC:2418872.
文摘著者:张蔚出版社:劳特利奇(Routledge)出版社出版时间:2024年12月此英文专著是国际权威劳特利奇出版社当代中国系列(Routledge Contemporary China Series)的最新一本英文专著,也是劳特利奇出版社戏剧和表演研究系列(Theatre&Performance Studies)的最新著作。全书共七章,从文化的属性,历史的渊源,人种的迁移等视角切人,探讨比较了地缘关系、表演形态中的中国北方汉族与少数民族、中国与东亚、东南亚和南亚在宗教信仰、文化习俗方面的关联、传播和交融,体现在动律体态上的特点及其对表演形式与流派的变革性影响。
基金Supported by the National Natural Science Foundation of China(32072749)。
文摘The purpose of this experiment was to investigate the effect and mechanism of quercetin on reproductive performance in perinatal sows.According to the similar principle of parity and body weight,24 perinatal sows were randomly divided into four treatments with six replicates,including normal control and three treatments fed by a basal diet supplemented with 0,0.025%,0.050%,and 0.075%quercetin,respectively.The feeding trial was conducted from 100 days of gestation to 28 days post-partum.Reproductive performance,colostrum composition,serum indexes of antioxidation,inflammation,hormones,and the diversity and relative abundance of fecal microflora were determined in perinatal sows.Compared with the control,quercetin significantly reduced the rate of constipation,serum content of malondialdehyde(MDA),prolactin(PRL),and progesterone(PROG),and significantly increased the content of serum estradiol(E2)and insulin-like growth factor-1(IGF-1)in colostrum of perinatal sows(P<0.05).Meanwhile,0.025%quercetin significantly increased glutathione(GSH)content in serum(P<0.05),0.050%quercetin significantly reduced the rate of backfat loss(P<0.05),and 0.075%quercetin significantly increased immunoglobulin M(IgM)content in colostrum of perinatal sows(P<0.05).In addition,0.050%and 0.075%quercetin significantly shortened estrus interval(P<0.05)and significantly increased the content of IgA and IgG in colostrum(P<0.05)and dopamine(DA)content in serum of perinatal sows(P<0.05).Quercetin significantly decreased the content of nitric oxide(NO),IL-1β,IL-6,TNF-α,and MCP-1 in serum(P<0.05)and significantly improved microflora abundance and diversity in feces of perinatal sows(P<0.05).In conclusion,dietary supplementation of quercetin reduced oxidative stress and inflammatory responses and regulated intestinal microflora in perinatal sows,thus improved reproductive performance in perinatal sows.Under this experimental condition,the optimal supplementation with dietary quercetin was 0.075%in perinatal sows.
基金support from the following for aspects of the research,authorship,and/or publication of this article:National Natural Science Foundation of China(Grant No.12302187)Innovation Program of Wuhan-Shuguang Project(Grant No.202201080102).
文摘When the protective and protected systems are detached,the former can be allowed to absorb the kinetic energy of the impacting projectile through large deformation without considering the back face signature of the latter.This paper presents a novel double-face knitted fabric(DFKF)designed for this very impacting scenario.Shooting tests equipped with high-speed camera were used to characterize the ballistic performance with the impact velocities ranging from 100 m/s to 450 m/s.The results showed that the ballistic limits(V_(bl))of DFKF are approximately triple and double that of its counterpart UD and plain fabrics,respectively.For mass-normalized metrics,the specific energy absorption(SEA)is 250%and 350%greater than the UD and plain fabrics at their corresponding V_(bl)s.The quasi-static tests showed that the DFKF displayed greater resilience,crease recovery properties,and flexibility,which also made it an especially better candidate than UD and plain weaves for the design of umbrella surface cloth.It was also found that DFKF is dependent on yarn count and the incorporation of spandex.A prototype anti-ballistic umbrella is manufactured using DFKF made of 200D multi-filament yarn.The ballistic performance is also sensitive to the impact site when the umbrella is subjected to impact.
基金supported by the National Natural Science Foundation of China(Gant Nos.11372291 and 11902298)。
文摘Detonation performance is crucial for evaluating the power of high explosives(HEs),and the equation of state(EOS)that accurately describes the high-temperature,high-pressure,and high-temperature,medium-pressure states of detonation products is key to assessing the damage efficiency of these energetic materials.This article examines the limitations of the VLW EOS in representing the thermodynamic states of explosive detonation gas products under high-temperature and medium-to high-pressure conditions.A new gas EOS for detonation products,called VHL(Virial-Han-Long),is proposed.The accuracy of VHL in describing gas states under high-temperature and medium-to high-pressure conditions is verified,and its performance in evaluating explosive detonation and working capabilities is explored.The results demonstrate that VHL exhibits high precision in calculating detonation performance.Subsequently,the detonation performance of three new HEs(ICM-101,ONC,and TNAZ)was calculated and compared to traditional HEs(TATB,CL-20,and HMX).The results indicate that ONC has superior detonation performance compared to the other explosives,while ICM-101 shows a detonation velocity similar to CL-20 but with slightly lower detonation pressure.The detonation characteristics of TNAZ are comparable to those of the standard HE HMX.From the perspective of products,considering the comprehensive work performance(mechanical work and detonation heat),both ONC and ICM-101demonstrate relatively superior performance.
基金Projects(52302447,52388102,52372369)supported by the National Natural Science Foundation of China。
文摘Following the fundamental characteristics of the porosity windbreak,this study suggests a new numerical investigation method for the wind field of the windbreak based on the porous medium physical model.This method can transform the reasonable matching problem of the porosity and windproof performance of the windbreak into a study of the relationship between the resistance coefficient of the porous medium and the aerodynamic load of the train.This study examines the influence of the hole type on the wind field behind the porosity windbreak.Then,the relationship between the resistance coefficient of the porous medium,the porosity of the windbreak,and the aerodynamic loads of the train is investigated.The results show that the porous media physical model can be used instead of the windbreak geometry to study the windbreak-train aerodynamic performance,and the process of using this method is suggested.
基金National Natural Science Foundation of China(Grant Nos.12172179,11802141 and U2341244)National Natural Science Foundation for Young Scientists of China(Grant No.12202207)+3 种基金China Postdoctoral Science Foundation(Grant No.2022M711623)Natural Science Foundation of Jiangsu Province(Grant No.BK20220968)Open Funds for Key Laboratory of Impact and Safety Engineering(Ningbo University),Ministry of Education(Grant No.CJ202201)Open Funds for Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province(Grant No.22kfgk03)。
文摘Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current research on the anti-penetration of aramid fabrics mostly focuses unilaterally on the structure and performance of aramid fabrics or the shape and size of projectiles,with fewer studies on the coupled effect of both on ballistic performance.This study analyzes how the coupling relationship(or size effect)between the projectile and fiber bundle dimensions affects the fabric ballistic performance from a mesoscopic scale perspective.Taking plain weave aramid fabric as the research object,considering different diameter projectiles,through a large number of ballistic impact tests and numerical simulations,parameters such as ballistic limit velocity,average energy absorption of fabric,and specific energy absorption ratio(average energy absorption of fabric divided by projectile cross-sectional area)are obtained for ballistic performance analysis.The influence law of projectile size on the ballistic performance of high-performance fabrics is as follows:The relative range of fitted ballistic limit velocity at different target positions gradually decreases and then stabilizes as the projectile diameter increases,indicating that the fabric structure effect gradually disappears at a projectile diameter of 12 mm;The average ballistic limit velocity at three impact positions,P1,P2,and P3,provides the corresponding ballistic limit velocity for 1000D aramid fabric,which increases with projectile diameter but the rate of increase slows down at an inflection point,which in this study occurs where the fabric structure effect nearly disappears at a projectile diameter of 12 mm;The energy absorption ratio increases and then decreases as the projectile diameter increases from 4 mm to 20 mm,reaching a peak at the diameter of 12 mm due to the gradual disappearance of the fabric structural effect.The projectile diameter of 12 mm corresponds to the coupling size of 11.159,which provides a size design reference for the macroscopic-based continuum models of aramid plain weave fabrics.
基金financially supported by the Fundamental Research Funds for the Central Universities(Grant No.30923011018)。
文摘The present study introduces a screw-pressing charging method to tackle deficiencies in automation and charge uniformity during the melt-casting of polymer-based energetic materials.To ensure the safety of the experiments,this study used inert materials with similar physical properties to partially substitute for the actual energetic components in the preparation of simulant materials.By thoroughly analyzing slurry physical properties,a simulation framework and an extensive performance evaluation method were developed.Such tools guide the design of the structure and configuration of process parameters.Results demonstrate that employing the Pin element significantly enhances radial mixing within the screw,minimizes temperature variations in the slurry,and improves both efficiency and safety in the mixing process.Further,adjustments such as widening the cone angle of the barrel,modifying the solid content of the slurry,and varying the speed of the screw can optimize the mechanical and thermal coupling in the flow field.These adjustments promote higher-quality slurry and create a safer production environment for the extrusion process.
文摘Because of an unfortunate mistake by authors,the Project(5227010679)of Foundation item was wrong.The corrected Project is shown as follows:Project(52271073).
文摘Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of boron.The results indicated that the PDA coating formed a fishing net structure on the surface of boron particles.The heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw boron.Specifically,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw boron.Simultaneously,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were evaluated.It was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,respectively.The peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@AP.Therefore,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.
基金the National Natural Science Foundation of China(Grant No.12072090).
文摘This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance systems of missiles is challenging.As our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy.The global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional PPF.Then,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities.Meanwhile,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify disturbances.The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots.
文摘The design of mini-missiles(MMs)presents several novel challenges.The stringent mission requirement to reach a target with a certain precision imposes a high guidance precision.The miniaturization of the size of MMs makes the design of the guidance,navigation,and control(GNC)have a larger-thanbefore impact on the main-body design(shape,motor,and layout design)and its design objective,i.e.,flight performance.Pursuing a trade-off between flight performance and guidance precision,all the relevant interactions have to be accounted for in the design of the main body and the GNC system.Herein,a multi-objective and multidisciplinary design optimization(MDO)is proposed.Disciplines pertinent to motor,aerodynamics,layout,trajectory,flight dynamics,control,and guidance are included in the proposed MDO framework.The optimization problem seeks to maximize the range and minimize the guidance error.The problem is solved by using the nondominated sorting genetic algorithm II.An optimum design that balances a longer range with a smaller guidance error is obtained.Finally,lessons learned about the design of the MM and insights into the trade-off between flight performance and guidance precision are given by comparing the optimum design to a design provided by the traditional approach.
基金Project(2023RC3066)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(2023JJ50079)supported by the Hunan Provincial Natural Science Foundation,China。
文摘Carbonized melamine foam has been recognized as a promising material for microwave absorption due to its exceptional thermal stability,lightweight,and remarkable dielectric properties.In this study,we investigated the impact of nitric acid oxidation on the surface of carbonized melamine foam and its microwave absorption properties.The treated foam exhibits optimal reflection loss of−21.51 dB at 13.20 GHz,with an effective absorption bandwidth of 7.04 GHz.The enhanced absorption properties are primarily attributed to the strengthened dielectric loss,improved impedance matching,and increased polarization losses resulting from the oxidized surfaces.This research demonstrates a promising new approach for research into surface treatments to improve the performances of microwave absorbers.
基金supported by the National Natural Science Foundation of China (6207319761933006)National International Science and Technology Cooperation Base on Railway Vehicle Operation Engineering of Beijing Jiaotong University (BMRV20KF08)。
文摘An adaptive control approach is presented in this paper for tracking desired trajectories in interactive manipulators. The controller design incorporates prescribed performance functions (PPFs) to improve dynamic performance. Notably, the performance of the output error is confined in an envelope characterized by exponential convergence, leading to convergence to zero. This feature ensures a prompt response from admittance control and establishes a reliable safety framework for interactions. Simulation results provide practical insights,demonstrating the viability of the control scheme proposed in this paper.
基金sponsored by the National Key Research and Development Program of China[Grant Nos.2020YFC0826804 and 2022YFC3320504]the National Natural Science Foundation of China[Grant No.11772059]。
文摘Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.
基金Project(U2106216)supported by the National Natural Science Foundation of China。
文摘In this manuscript,the neat epoxy(EP)and functionalized Fe_(3)O_(4)(G-Fe_(3)O_(4))reinforced epoxy(G-Fe_(3)O_(4)/EP)coatings were cured under different temperatures,and the effect of the low curing temperature on the anticorrosion performance was investigated.The experimental results show that the epoxy-amine ring-open addition reaction mainly exists in the curing process,and the activation energies of the reaction for the two coatings are 55.84 and 53.29 kJ/mol,respectively.For the coatings cured at the low temperature,almost no pores could be detected on the fracture surface,but the presentence of the rough regions reflects the poor curing state.As compared with the samples cured at the high temperature,the anticorrosion performance of the coatings with the low curing temperature is worse,and the decrease rate of the anticorrosion performance is slower,because of the poor curing state and low adhesion obtained at the low temperature.
