Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliabilit...Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliability centered maintenance of a launching system are presented in this paper. The common methods for functional impor- tant product determination, failure modes and effect analysis （ FMEA ） and logic decision analysis were illustrated and the basic methods for maintenance interval calculation models were studied based on availability. According to the research, the reliability centered maintenance plan of a certain launching system was given.展开更多
A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in th...A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in the breech chamber,and the other is arranged in the barrel.The breech chamber charge was ignited first,and the charges in the auxiliary chambers were ignited by the high-temperature,highpressure combustible gas trailing the projectile.In this way,the combustible gas in the auxiliary chambers could compensate for the pressure drop caused by the movement of the projectile.The proposed device features the advantage of launching a projectile with high muzzle velocity without exceeding the maximum pressure in the chamber.In order to obtain some internal ballistic characteristics of the launch system,some critical structure,such as the length of the filter cartridge auxiliary charge,the combustion degree of the propellant in the chamber,and the length of the barrel,are discussed.The experimental results show that with the increased auxiliary charge length,a pressure plateau or even a secondary peak pressure can be formed,which is less than the peak pressure.The projectile velocity increased by 23.57%,14.64%,and 7.65%when the diaphragm thickness was 0 mm,1 mm,and2 mm,respectively.The muzzle velocity of the projectile can be increased by 13.42%by increasing the length of the barrel.Under the same charge condition,with the increase of barrel length,the energy utilization rate of propellant increases by 28.64%.展开更多
High-altitude rescue is dangerous and difficult.A new rescue method is proposed here based on electromagnetically launched tethered nets.Four electromagnetic launching units are attached to a revolving platform,from w...High-altitude rescue is dangerous and difficult.A new rescue method is proposed here based on electromagnetically launched tethered nets.Four electromagnetic launching units are attached to a revolving platform,from which four projectiles are launched.The four projectiles are connected to a tethered net,bringing it into motion.As the tethered net approaches and comes into contact with the object,the object will be trapped,and the rescue task will then be completed as long as the tethered net can be restored along with the trapped object.The structural design of the electromagnetic launching unit is presented with the established mathematical model.The motion characteristics of the launched projectiles are studied and their exit velocities are modeled and measured.Terminal velocities of these projectiles are characterized,and the final shape and position of the projected tethered net are obtained.This study validates the feasibility of using electromagnetically launched tethered nets to perform high-altitude rescues.展开更多
As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canist...As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.展开更多
Underwater launch is a transient vibration process under the impact load.The hydrodynamic calculation is an important part of equipment research.In this paper,firstly,combining the theory of the Euler-Bernoulli beam a...Underwater launch is a transient vibration process under the impact load.The hydrodynamic calculation is an important part of equipment research.In this paper,firstly,combining the theory of the Euler-Bernoulli beam and the potential flow,the transfer equation of the Euler-Bernoulli beam considering the hydroelastic effect is derived,which expands the application scope of the transfer matrix.The correctness of the transfer matrix for the beam with hydroelastic behaviors is verified by comparison with the results of the finite element analysis.Then the dynamics model of the underwater launch system is established based on the multibody system transfer matrix method,and the beam with hydroelastic behaviors is employed as the external vehicle.Subsequently,the overall transfer and dynamic equation are derived,resulting in the solution of the wet natural frequency and the dynamic response under the impact load.The comparison with experimental data validates the dynamics model and simulation results and ensures its reliability in practical applications.The dynamic of the system demonstrates that the launching interval and adjacent tube effect will exert an influence on the subsequent emission.This research provides a fast and efficient method for the dynamic calculation of the underwater launch system.展开更多
At 11:00 p.m. on January 13, 2026, floodlights illuminated the launch pad at the Hainan Commercial Space Launch Site in Wenchang,south China’s Hainan Province. A Long March-8A (CZ-8A) carrier rocket lifted off with a...At 11:00 p.m. on January 13, 2026, floodlights illuminated the launch pad at the Hainan Commercial Space Launch Site in Wenchang,south China’s Hainan Province. A Long March-8A (CZ-8A) carrier rocket lifted off with a steady roar, its exhaust lighting up the night sky as it delivered a satellite into its designated orbit.The development of China’s first commercial space launch site has been striking. Since its inaugural launch in2024, it has completed 11 missions in less than 14 months—each a success.展开更多
Rwanda-China alliance launches youth innovation union,opening doors for African entrepreneurs On a warm afternoon in Kigali,students filled a conference hall at the University of Rwanda,sitting shoulder to shoulder wi...Rwanda-China alliance launches youth innovation union,opening doors for African entrepreneurs On a warm afternoon in Kigali,students filled a conference hall at the University of Rwanda,sitting shoulder to shoulder with lecturers and visitors from China,unsure at first how significant the moment would be.Some came out of curiosity.Others came with hope.By the end of the ceremony,many felt they had witnessed more than the launch of a new academic centre-they had watched a door open.展开更多
The proliferation of carrier aircraft and the integration of unmanned aerial vehicles(UAVs)on aircraft carriers present new challenges to the automation of launch and recovery operations.This paper investigates a coll...The proliferation of carrier aircraft and the integration of unmanned aerial vehicles(UAVs)on aircraft carriers present new challenges to the automation of launch and recovery operations.This paper investigates a collaborative scheduling problem inherent to the operational processes of carrier aircraft,where launch and recovery tasks are conducted concurrently on the flight deck.The objective is to minimize the cumulative weighted waiting time in the air for recovering aircraft and the cumulative weighted delay time for launching aircraft.To tackle this challenge,a multiple population self-adaptive differential evolution(MPSADE)algorithm is proposed.This method features a self-adaptive parameter updating mechanism that is contingent upon population diversity,an asynchronous updating scheme,an individual migration operator,and a global crossover mechanism.Additionally,comprehensive experiments are conducted to validate the effectiveness of the proposed model and algorithm.Ultimately,a comparative analysis with existing operation modes confirms the enhanced efficiency of the collaborative operation mode.展开更多
The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than prev...The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than previously reported for a recoverable nine-engine liquid-propellant rocket.Based on the Radiative Transfer Equation(RTE),this study employs the discrete transfer method to solve the transient RTE problem using physical properties to describe the problem while avoiding the need to directly solve mathematical equations.The proposed method can effectively determine the radiative heat flux of the flow field and is applicable to problems involving various geometries.Calculations reveal that during the ascent phase of the rocket,the radiative heat flux at the base of the vehicle reaches its maximum in the initial stages of the lift-off,reaching a maximum of~50 kW/m^(2),which is 2.24 times the maximum value during the return phase.During the deceleration stage of re-entry into the atmosphere,the maximum radiative heat flux recorded on the sidewall of the rocket is 29.1 kW/m^(2);the maximum heat flux on the bottom surface is approximately 22.3 kW/m^(2),accounting for 76.6%of that on the rocket's sidewall.This provides a basis for the thermal protection design of the rocket's bottom and walls as well as for the thermal management of cryogenic propellant tanks.Future research will involve ground engine testing and flight experiments to further validate the proposed model.展开更多
The relative characteristics of motion of the fuel and shell upon launching is analyzed. By means of mechanical analysis and calculation, it is proposed that relative motion exists not only in the ranges between the f...The relative characteristics of motion of the fuel and shell upon launching is analyzed. By means of mechanical analysis and calculation, it is proposed that relative motion exists not only in the ranges between the fuel and shell of the warhead, but also in the fuel in different positions. The result of study indicates that the position of the fuel in the warhead has a marked influence on the relative motion, while the frictional coefficient between the fuel and shell has less influence upon it.展开更多
This paper begins with a discussion on the significance of multi-physical fields in the research of railgun launching mechanism, followed by an introduction of research work about dynamic measurements and numerical si...This paper begins with a discussion on the significance of multi-physical fields in the research of railgun launching mechanism, followed by an introduction of research work about dynamic measurements and numerical simulations. The application of some measurement methods including the atomic emission spectrum, fiber-optic strain, optical level, pulsed X-ray, and high-speed video in observing the launching process was introduced. The models about the electromechanical dynamic processes and multi-physical fields in a railgun were developed. The mechanisms of the grooving, arc transition, and gouging were analyzed. These work provided a deeper understanding of launching mechanism of electromagnetic railgun. Some issues about the tactical railgun, such as the fiber composite overwrapped barrel, recoil,loading modes and eddy current loss were also discussed. Taking a medium-caliber launcher as an example, the basic process of design and analysis was introduced.展开更多
In recent years, Chinese Long March(LM) launchers have experienced several launch failures, most of which occurred in their propulsion systems, and this paper studies Autonomous Mission Reconstruction(AMRC) technology...In recent years, Chinese Long March(LM) launchers have experienced several launch failures, most of which occurred in their propulsion systems, and this paper studies Autonomous Mission Reconstruction(AMRC) technology to alleviate losses due to these failures. The status of the techniques related to AMRC, including trajectory and mission planning, guidance methods,and fault tolerant technologies, are reviewed, and their features are compared, which reflect the challenges faced by AMRC technology. After a brief introduction about the failure modes of engines that can occur during flight, and the fundamentals of trajectory planning and joint optimization of the target orbit and flight path, an AMRC algorithm is proposed for geostationary transfer orbit launch missions. The algorithm evaluates the residual performance onboard, and plans new objectives and corresponding flight path by iterative guidance mode or segmented state triggered optimization methods in real-time. Three failure scenarios that have occurred during previous LM missions are simulated to check the robustness of the algorithm: imminent explosion risk of the boosters’ engines, thrust drop during the first stage of flight, and being unable to start the engine during the second stage. The payloads would fall from space according to the current design under these conditions, but they were saved with the AMRC algorithm in the simulations, which allowed the rocket to get into the target orbit as intended or the payloads were deployed in other orbits without crashing. Although spaceflight can be very unforgiving, the AMRC algorithm has the potential to avoid the total loss of a launch mission when faced with these kinds of typical failures.展开更多
It’s very complicated to calculate and analyze the wave and current loads on naval architectures since the sea condition is uncertain and complicated and the determinants vary from different form types and dimensions...It’s very complicated to calculate and analyze the wave and current loads on naval architectures since the sea condition is uncertain and complicated and the determinants vary from different form types and dimensions. For calculating the wave and current loads on upright small-long-size pipe, the Morrison equation is practical and applied. Jacket platform is a kind of offshore space frame structure comprised of lots of poles that are circular cylinders with small diameter and in the oblique status relative to seabed. In this paper, based on Morrison equation, the specific method and procedure calculating the wave and current loads on launching jacket are given and applied on a typical launching jacket. The instance shows that the method and procedure are convenient and make the calculation and analysis in good agreement with actual launching.展开更多
Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include...Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include the business process construction of launching mission planning,validation of the effectiveness of the launching scheme,etc.This paper pro-poses the agile space emergency launching mission planning simulation and verification method,which systematically con-structs the overall technical framework of space emergency launching mission planning with multi-field area,multi-platform and multi-task parallel under the constraint of resource schedul-ing for the first time.It supports flexible reconstruction of mis-sion planning processes such as launching target planning,tra-jectory planning,path planning,action planning and launching time analysis,and can realize on-demand assembly of operation links under different mission scenarios and different plan condi-tions,so as to quickly modify and generate launching schemes.It supports the fast solution of rocket trajectory data and the accurate analysis of multi-point salvo time window recheck and can realize the fast conflict resolution of launching missions in the dimensions of launching position and launching window sequence.It supports lightweight scenario design,modular flexi-ble simulation,based on launching style,launching platform,launching rules,etc.,can realize the independent mapping of mission planning results to two-dimensional and three-dimen-sional visual simulation models,so as to achieve a smooth con-nection between mission planning and simulation.展开更多
In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure ...In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure from the muzzle)and the muzzle velocity are measured.Compared with the classical methods,the actual muzzle time is obtained by eliminating the ignition delay.The comparative analysis method is proposed with numerical simulations established by the transfer matrix method for multibody systems.The experiment results indicate that the proposed measurement system can effectively measure the actual muzzle time and reduce the error of classical methods,which match well with the simulation results showing the launch dynamics model is reliable and helpful for further analysis and design of the MLRS.展开更多
A hybrid approach is presented to investigate the dynamic behavior of anaxially slide-spin flexible rocket with nonlinear clearance. The equations of motion of the flexiblerocket are derived based upon Euler-Bernoulli...A hybrid approach is presented to investigate the dynamic behavior of anaxially slide-spin flexible rocket with nonlinear clearance. The equations of motion of the flexiblerocket are derived based upon Euler-Bernoulli beam theory and Hamilton principle and the finiteelement method. The characteristics of clearance between the spinning rocket and launcher areconsidered to be piecewise linear. Numerical solution is developed by direct integration method anddemonstrates the validity of the method. The coupled dynamic behavior of axial motion and transversevibrations of rocket are analyzed, and the influences of axially moving acceleration, spin speed,linking stiffness of elastic 'shoes', and the nonlinearity of clearance on the motion attitude ofrocket are studied.展开更多
The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational eff...The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled artillery.This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery.Recognizing the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system.This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery.Additionally,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process.Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.展开更多
For characterizing a series augmented railgun launching process,the simulation and experiment were done.In the experiment,only observation of muzzle voltage,current and armature position were insufficient to analyze l...For characterizing a series augmented railgun launching process,the simulation and experiment were done.In the experiment,only observation of muzzle voltage,current and armature position were insufficient to analyze launching process deeply since armature velocity,resistance force and voltage drop of armature were also important to the launching process.In the present work,based on MATLAB/SIMULINK software platform,the simulation model was built,and the dynamic characteristics of system were simulated.Furthermore,the variations of armature velocity,total resistance force and voltage drop of armature against time were investigated based on the data of B-dot probes(to measure position of armature),Rogowsky coil(to monitor current) and high voltage probes(to observe muzzle voltage).The results indicated that,the voltage drop of armature and the total resistance force showed roughly regulartendency.There were obvious stages observed in the two-turn series augmented railgun launching process.展开更多
The aim of this investigation is to research the initial ignition of the underwater-launching solid rocket motor.The MIXTURE multiple-phase model was set to simulate the initial ignition.The water vaporization was res...The aim of this investigation is to research the initial ignition of the underwater-launching solid rocket motor.The MIXTURE multiple-phase model was set to simulate the initial ignition.The water vaporization was researched and the energy transfer was added to the energy equations.The flow field and the vaporization were calculated coupled.The initial ignition process of the underwater solid rocket motor is obtained and the vaporization influence to the underwater launching is analyzed.The ＂neck＂,＂inverted jet＂ and ＂eruption＂ phenomenon of the bubble are observed.The bubble increases more rapidly because the steam mass added to the fuel.The temperature is lower considering the vaporization because the steam enthalpy is lower than the fuel enthalpy and the flow field of the initial ignition of the underwater-launching solid rocket motor is accordant well to the reference.展开更多
To solve the sequencing problem in mixed-model flexible assembly lines (MMFALs) with variable launching intervals, a mathematical model aiming to minimize the cost of utility and idle times is developed. To obtain hig...To solve the sequencing problem in mixed-model flexible assembly lines (MMFALs) with variable launching intervals, a mathematical model aiming to minimize the cost of utility and idle times is developed. To obtain high-quality sequences, an advanced scatter search (ASS) algorithm is proposed. A heuristic approach, i.e. launching intervals between products algorithm (LIBPA), is incorporated into the ASS algorithm to solve the launching interval problem for each sequence. Numerical experiments with different scales are conducted to compare the performance of ASS with genetic algorithm (GA). In addition, we compare the cost of variable launching intervals approach with fixed launching intervals approach. The results indicate that the ASS is efficient and effective, and considering variable launching intervals in mixed-model assembly lines (MMALs) sequencing problem can improve the performance of the line.展开更多
文摘Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliability centered maintenance of a launching system are presented in this paper. The common methods for functional impor- tant product determination, failure modes and effect analysis （ FMEA ） and logic decision analysis were illustrated and the basic methods for maintenance interval calculation models were studied based on availability. According to the research, the reliability centered maintenance plan of a certain launching system was given.
基金financially supported by the National Natural Science Foundation of China under Project No.51874267 and No.12272374the Fundamental Research Funds for the Central Universities under Project Nos.WK2480000008,WK2480000007,and WK2320000049。
文摘A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in the breech chamber,and the other is arranged in the barrel.The breech chamber charge was ignited first,and the charges in the auxiliary chambers were ignited by the high-temperature,highpressure combustible gas trailing the projectile.In this way,the combustible gas in the auxiliary chambers could compensate for the pressure drop caused by the movement of the projectile.The proposed device features the advantage of launching a projectile with high muzzle velocity without exceeding the maximum pressure in the chamber.In order to obtain some internal ballistic characteristics of the launch system,some critical structure,such as the length of the filter cartridge auxiliary charge,the combustion degree of the propellant in the chamber,and the length of the barrel,are discussed.The experimental results show that with the increased auxiliary charge length,a pressure plateau or even a secondary peak pressure can be formed,which is less than the peak pressure.The projectile velocity increased by 23.57%,14.64%,and 7.65%when the diaphragm thickness was 0 mm,1 mm,and2 mm,respectively.The muzzle velocity of the projectile can be increased by 13.42%by increasing the length of the barrel.Under the same charge condition,with the increase of barrel length,the energy utilization rate of propellant increases by 28.64%.
基金Zhejiang Provincial Natural Science Foundation of China(No.LY22E050013)China Postdoctoral Science Foundation(No.2021M690545)National Natural Science Foundation of China(No.51805124).
文摘High-altitude rescue is dangerous and difficult.A new rescue method is proposed here based on electromagnetically launched tethered nets.Four electromagnetic launching units are attached to a revolving platform,from which four projectiles are launched.The four projectiles are connected to a tethered net,bringing it into motion.As the tethered net approaches and comes into contact with the object,the object will be trapped,and the rescue task will then be completed as long as the tethered net can be restored along with the trapped object.The structural design of the electromagnetic launching unit is presented with the established mathematical model.The motion characteristics of the launched projectiles are studied and their exit velocities are modeled and measured.Terminal velocities of these projectiles are characterized,and the final shape and position of the projected tethered net are obtained.This study validates the feasibility of using electromagnetically launched tethered nets to perform high-altitude rescues.
基金supported by National Natural Science Foundation of China(Grant No.92266201).
文摘As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.
基金supported by the National Natural Science Foundation of China(Grant No.92266201).
文摘Underwater launch is a transient vibration process under the impact load.The hydrodynamic calculation is an important part of equipment research.In this paper,firstly,combining the theory of the Euler-Bernoulli beam and the potential flow,the transfer equation of the Euler-Bernoulli beam considering the hydroelastic effect is derived,which expands the application scope of the transfer matrix.The correctness of the transfer matrix for the beam with hydroelastic behaviors is verified by comparison with the results of the finite element analysis.Then the dynamics model of the underwater launch system is established based on the multibody system transfer matrix method,and the beam with hydroelastic behaviors is employed as the external vehicle.Subsequently,the overall transfer and dynamic equation are derived,resulting in the solution of the wet natural frequency and the dynamic response under the impact load.The comparison with experimental data validates the dynamics model and simulation results and ensures its reliability in practical applications.The dynamic of the system demonstrates that the launching interval and adjacent tube effect will exert an influence on the subsequent emission.This research provides a fast and efficient method for the dynamic calculation of the underwater launch system.
文摘At 11:00 p.m. on January 13, 2026, floodlights illuminated the launch pad at the Hainan Commercial Space Launch Site in Wenchang,south China’s Hainan Province. A Long March-8A (CZ-8A) carrier rocket lifted off with a steady roar, its exhaust lighting up the night sky as it delivered a satellite into its designated orbit.The development of China’s first commercial space launch site has been striking. Since its inaugural launch in2024, it has completed 11 missions in less than 14 months—each a success.
文摘Rwanda-China alliance launches youth innovation union,opening doors for African entrepreneurs On a warm afternoon in Kigali,students filled a conference hall at the University of Rwanda,sitting shoulder to shoulder with lecturers and visitors from China,unsure at first how significant the moment would be.Some came out of curiosity.Others came with hope.By the end of the ceremony,many felt they had witnessed more than the launch of a new academic centre-they had watched a door open.
文摘The proliferation of carrier aircraft and the integration of unmanned aerial vehicles(UAVs)on aircraft carriers present new challenges to the automation of launch and recovery operations.This paper investigates a collaborative scheduling problem inherent to the operational processes of carrier aircraft,where launch and recovery tasks are conducted concurrently on the flight deck.The objective is to minimize the cumulative weighted waiting time in the air for recovering aircraft and the cumulative weighted delay time for launching aircraft.To tackle this challenge,a multiple population self-adaptive differential evolution(MPSADE)algorithm is proposed.This method features a self-adaptive parameter updating mechanism that is contingent upon population diversity,an asynchronous updating scheme,an individual migration operator,and a global crossover mechanism.Additionally,comprehensive experiments are conducted to validate the effectiveness of the proposed model and algorithm.Ultimately,a comparative analysis with existing operation modes confirms the enhanced efficiency of the collaborative operation mode.
文摘The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than previously reported for a recoverable nine-engine liquid-propellant rocket.Based on the Radiative Transfer Equation(RTE),this study employs the discrete transfer method to solve the transient RTE problem using physical properties to describe the problem while avoiding the need to directly solve mathematical equations.The proposed method can effectively determine the radiative heat flux of the flow field and is applicable to problems involving various geometries.Calculations reveal that during the ascent phase of the rocket,the radiative heat flux at the base of the vehicle reaches its maximum in the initial stages of the lift-off,reaching a maximum of~50 kW/m^(2),which is 2.24 times the maximum value during the return phase.During the deceleration stage of re-entry into the atmosphere,the maximum radiative heat flux recorded on the sidewall of the rocket is 29.1 kW/m^(2);the maximum heat flux on the bottom surface is approximately 22.3 kW/m^(2),accounting for 76.6%of that on the rocket's sidewall.This provides a basis for the thermal protection design of the rocket's bottom and walls as well as for the thermal management of cryogenic propellant tanks.Future research will involve ground engine testing and flight experiments to further validate the proposed model.
文摘The relative characteristics of motion of the fuel and shell upon launching is analyzed. By means of mechanical analysis and calculation, it is proposed that relative motion exists not only in the ranges between the fuel and shell of the warhead, but also in the fuel in different positions. The result of study indicates that the position of the fuel in the warhead has a marked influence on the relative motion, while the frictional coefficient between the fuel and shell has less influence upon it.
文摘This paper begins with a discussion on the significance of multi-physical fields in the research of railgun launching mechanism, followed by an introduction of research work about dynamic measurements and numerical simulations. The application of some measurement methods including the atomic emission spectrum, fiber-optic strain, optical level, pulsed X-ray, and high-speed video in observing the launching process was introduced. The models about the electromechanical dynamic processes and multi-physical fields in a railgun were developed. The mechanisms of the grooving, arc transition, and gouging were analyzed. These work provided a deeper understanding of launching mechanism of electromagnetic railgun. Some issues about the tactical railgun, such as the fiber composite overwrapped barrel, recoil,loading modes and eddy current loss were also discussed. Taking a medium-caliber launcher as an example, the basic process of design and analysis was introduced.
基金co-supported by International Academy of Astronautics (IAA) study group SG 3.32the National Natural Science Foundation of China (No. 61773341)
文摘In recent years, Chinese Long March(LM) launchers have experienced several launch failures, most of which occurred in their propulsion systems, and this paper studies Autonomous Mission Reconstruction(AMRC) technology to alleviate losses due to these failures. The status of the techniques related to AMRC, including trajectory and mission planning, guidance methods,and fault tolerant technologies, are reviewed, and their features are compared, which reflect the challenges faced by AMRC technology. After a brief introduction about the failure modes of engines that can occur during flight, and the fundamentals of trajectory planning and joint optimization of the target orbit and flight path, an AMRC algorithm is proposed for geostationary transfer orbit launch missions. The algorithm evaluates the residual performance onboard, and plans new objectives and corresponding flight path by iterative guidance mode or segmented state triggered optimization methods in real-time. Three failure scenarios that have occurred during previous LM missions are simulated to check the robustness of the algorithm: imminent explosion risk of the boosters’ engines, thrust drop during the first stage of flight, and being unable to start the engine during the second stage. The payloads would fall from space according to the current design under these conditions, but they were saved with the AMRC algorithm in the simulations, which allowed the rocket to get into the target orbit as intended or the payloads were deployed in other orbits without crashing. Although spaceflight can be very unforgiving, the AMRC algorithm has the potential to avoid the total loss of a launch mission when faced with these kinds of typical failures.
基金Supported by Item of Doctor Subject of Colleges and University (No.2000014125) and the Education Office of Liaoning Province (No.05l091).
文摘It’s very complicated to calculate and analyze the wave and current loads on naval architectures since the sea condition is uncertain and complicated and the determinants vary from different form types and dimensions. For calculating the wave and current loads on upright small-long-size pipe, the Morrison equation is practical and applied. Jacket platform is a kind of offshore space frame structure comprised of lots of poles that are circular cylinders with small diameter and in the oblique status relative to seabed. In this paper, based on Morrison equation, the specific method and procedure calculating the wave and current loads on launching jacket are given and applied on a typical launching jacket. The instance shows that the method and procedure are convenient and make the calculation and analysis in good agreement with actual launching.
文摘Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include the business process construction of launching mission planning,validation of the effectiveness of the launching scheme,etc.This paper pro-poses the agile space emergency launching mission planning simulation and verification method,which systematically con-structs the overall technical framework of space emergency launching mission planning with multi-field area,multi-platform and multi-task parallel under the constraint of resource schedul-ing for the first time.It supports flexible reconstruction of mis-sion planning processes such as launching target planning,tra-jectory planning,path planning,action planning and launching time analysis,and can realize on-demand assembly of operation links under different mission scenarios and different plan condi-tions,so as to quickly modify and generate launching schemes.It supports the fast solution of rocket trajectory data and the accurate analysis of multi-point salvo time window recheck and can realize the fast conflict resolution of launching missions in the dimensions of launching position and launching window sequence.It supports lightweight scenario design,modular flexi-ble simulation,based on launching style,launching platform,launching rules,etc.,can realize the independent mapping of mission planning results to two-dimensional and three-dimen-sional visual simulation models,so as to achieve a smooth con-nection between mission planning and simulation.
文摘In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure from the muzzle)and the muzzle velocity are measured.Compared with the classical methods,the actual muzzle time is obtained by eliminating the ignition delay.The comparative analysis method is proposed with numerical simulations established by the transfer matrix method for multibody systems.The experiment results indicate that the proposed measurement system can effectively measure the actual muzzle time and reduce the error of classical methods,which match well with the simulation results showing the launch dynamics model is reliable and helpful for further analysis and design of the MLRS.
基金This project is supported by Science Foundation of Shanghai Municipal Co-mmission of Education, China(No.98AJ01) Provincial Natural Science Foundation of Shanghai, China(No.03ZR14032).
文摘A hybrid approach is presented to investigate the dynamic behavior of anaxially slide-spin flexible rocket with nonlinear clearance. The equations of motion of the flexiblerocket are derived based upon Euler-Bernoulli beam theory and Hamilton principle and the finiteelement method. The characteristics of clearance between the spinning rocket and launcher areconsidered to be piecewise linear. Numerical solution is developed by direct integration method anddemonstrates the validity of the method. The coupled dynamic behavior of axial motion and transversevibrations of rocket are analyzed, and the influences of axially moving acceleration, spin speed,linking stiffness of elastic 'shoes', and the nonlinearity of clearance on the motion attitude ofrocket are studied.
基金supported by the National Natural Science Foundation of China (Grant Number:12372093)。
文摘The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled artillery.This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery.Recognizing the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system.This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery.Additionally,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process.Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.
文摘For characterizing a series augmented railgun launching process,the simulation and experiment were done.In the experiment,only observation of muzzle voltage,current and armature position were insufficient to analyze launching process deeply since armature velocity,resistance force and voltage drop of armature were also important to the launching process.In the present work,based on MATLAB/SIMULINK software platform,the simulation model was built,and the dynamic characteristics of system were simulated.Furthermore,the variations of armature velocity,total resistance force and voltage drop of armature against time were investigated based on the data of B-dot probes(to measure position of armature),Rogowsky coil(to monitor current) and high voltage probes(to observe muzzle voltage).The results indicated that,the voltage drop of armature and the total resistance force showed roughly regulartendency.There were obvious stages observed in the two-turn series augmented railgun launching process.
文摘The aim of this investigation is to research the initial ignition of the underwater-launching solid rocket motor.The MIXTURE multiple-phase model was set to simulate the initial ignition.The water vaporization was researched and the energy transfer was added to the energy equations.The flow field and the vaporization were calculated coupled.The initial ignition process of the underwater solid rocket motor is obtained and the vaporization influence to the underwater launching is analyzed.The ＂neck＂,＂inverted jet＂ and ＂eruption＂ phenomenon of the bubble are observed.The bubble increases more rapidly because the steam mass added to the fuel.The temperature is lower considering the vaporization because the steam enthalpy is lower than the fuel enthalpy and the flow field of the initial ignition of the underwater-launching solid rocket motor is accordant well to the reference.
基金the National Natural Science Foundation of China(No.71071115)the National High Technology Research and Development Program (863) of China(No.2009AA043000)
文摘To solve the sequencing problem in mixed-model flexible assembly lines (MMFALs) with variable launching intervals, a mathematical model aiming to minimize the cost of utility and idle times is developed. To obtain high-quality sequences, an advanced scatter search (ASS) algorithm is proposed. A heuristic approach, i.e. launching intervals between products algorithm (LIBPA), is incorporated into the ASS algorithm to solve the launching interval problem for each sequence. Numerical experiments with different scales are conducted to compare the performance of ASS with genetic algorithm (GA). In addition, we compare the cost of variable launching intervals approach with fixed launching intervals approach. The results indicate that the ASS is efficient and effective, and considering variable launching intervals in mixed-model assembly lines (MMALs) sequencing problem can improve the performance of the line.
