Most downloaded articles
2024, 25(4):5-12.
Abstract:
Aimed at the problems that structure and function of aero-engine are complex, construction of Bayesian network is difficult, and it is difficult to obtain the exact value of node conditional probability, in this paper, a knowledge graph with fuzzy Bayesian network (KG-FBN) inference fault diagnosis method is proposed. Firstly, on the basis of large-scale historical fault data, an aero-engine fault knowledge graph is constructed by using the knowledge graph technology. Secondly, a mapping method of “knowledge graph-Bayesian network” is proposed to rapidly construct Bayesian network, and introduce fuzzy set theory to solve the uncertainty problem of probability parameters in engineering practice. Finally, an example is given to verify the feasibility of the proposed method. The results show that the proposed method can improve the efficiency of Bayesian network construction and achieve uncertain inference in fault diagnosis, can be also used for optimizing diagnostic strategies, and can improve equipment reliability, and is strong in engineering application value.
Aimed at the problems that structure and function of aero-engine are complex, construction of Bayesian network is difficult, and it is difficult to obtain the exact value of node conditional probability, in this paper, a knowledge graph with fuzzy Bayesian network (KG-FBN) inference fault diagnosis method is proposed. Firstly, on the basis of large-scale historical fault data, an aero-engine fault knowledge graph is constructed by using the knowledge graph technology. Secondly, a mapping method of “knowledge graph-Bayesian network” is proposed to rapidly construct Bayesian network, and introduce fuzzy set theory to solve the uncertainty problem of probability parameters in engineering practice. Finally, an example is given to verify the feasibility of the proposed method. The results show that the proposed method can improve the efficiency of Bayesian network construction and achieve uncertain inference in fault diagnosis, can be also used for optimizing diagnostic strategies, and can improve equipment reliability, and is strong in engineering application value.
2024, 25(4):28-32.
Abstract:
Lightning breakdown voltage is a significant parameter in judging whether lightning spark is enabled to generate in the fuel tank when an aircraft is struck by lightning. To investigate the lightning breakdown voltage of small gaps in aircraft fuel pipes installation, a test setup is built, and an adjustable impulse voltage generator is adopted to generate the lightning voltage waveform in accordance to the standard SAE ARP5412B. The test results show that the minimum value of critical withstood breakdown voltage measured in the laboratory environment is 9.0 kV at the installation gap of 3 mm. The types of components around the fuel pipes in fuel tank and the installation forms of the fuel pipes are almost not affected by the lightning breakdown voltage of the installation gap. The effects of the lightning breakdown voltage on the fuel pipes in diameter and on the surface of fuel pipes paint layer are negligible. The installation gap of 3 mm should be in good keep. The withstood breakdown voltage value increases from 9.9 kV to 22.5 kV by applying 1 mm thick sealant on the component surface, showing that the voltage amplitude required for gap lightning breakdown is greatly increased. The researches indicate that coating sealant on the surface of fuel pipes is an effective measure to reduce the risk of lightning breakdown in small gaps. The tests results and research conclusions of this paper are available for reference and basis.
Lightning breakdown voltage is a significant parameter in judging whether lightning spark is enabled to generate in the fuel tank when an aircraft is struck by lightning. To investigate the lightning breakdown voltage of small gaps in aircraft fuel pipes installation, a test setup is built, and an adjustable impulse voltage generator is adopted to generate the lightning voltage waveform in accordance to the standard SAE ARP5412B. The test results show that the minimum value of critical withstood breakdown voltage measured in the laboratory environment is 9.0 kV at the installation gap of 3 mm. The types of components around the fuel pipes in fuel tank and the installation forms of the fuel pipes are almost not affected by the lightning breakdown voltage of the installation gap. The effects of the lightning breakdown voltage on the fuel pipes in diameter and on the surface of fuel pipes paint layer are negligible. The installation gap of 3 mm should be in good keep. The withstood breakdown voltage value increases from 9.9 kV to 22.5 kV by applying 1 mm thick sealant on the component surface, showing that the voltage amplitude required for gap lightning breakdown is greatly increased. The researches indicate that coating sealant on the surface of fuel pipes is an effective measure to reduce the risk of lightning breakdown in small gaps. The tests results and research conclusions of this paper are available for reference and basis.
2024, 25(4):1-4.
Abstract:
The Statute of an educational institution is the basic system that regulates the ground rules of the institution’s educational and training activities. Echoing the national and military laws and regulations, it plays a guiding role in the formulation of the institution’s internal rules and regulations. In the process of formulation, a holistic approach should be taken to promote the unity of the top-level design and specific measures,higher education and military education, requirements of the times and the function and mission, historical inheritance and long-term planning, and common requirements and individual development. Only in this way can the statutes effectively square with the development direction, pool the will and strength, stimulate the driving force, demonstrate the enterprising attitude, and therefore to support the high-quality development.
The Statute of an educational institution is the basic system that regulates the ground rules of the institution’s educational and training activities. Echoing the national and military laws and regulations, it plays a guiding role in the formulation of the institution’s internal rules and regulations. In the process of formulation, a holistic approach should be taken to promote the unity of the top-level design and specific measures,higher education and military education, requirements of the times and the function and mission, historical inheritance and long-term planning, and common requirements and individual development. Only in this way can the statutes effectively square with the development direction, pool the will and strength, stimulate the driving force, demonstrate the enterprising attitude, and therefore to support the high-quality development.
2024, 25(4):49-57.
Abstract:
In joint operation planning, there is an input information whose scientific nature, rationality and operability of joint operation conception should be fully verified. A qualitative verification mode of joint operation conception is formed based on the hierarchical DEMATEL algorithm and combined with “Wuli-Shili-Renli” methodology suitable for dealing with complex giant system problems. The essential characteristic, verification needs and verification methods of joint operation conception are analyzed, the qualitative evaluation index system of joint operation conception is set up, the analysis framework based on the three-attributes criteria of “Wuli-Shili-Renli” is constructed, and the analysis framework based on the five-dimension criteria of purpose, rationality, feasibility, coordination and risk are built. The case calculation and result analysis are made. Finally，the method is provided for the qualitative verification mode of joint operation conception.
In joint operation planning, there is an input information whose scientific nature, rationality and operability of joint operation conception should be fully verified. A qualitative verification mode of joint operation conception is formed based on the hierarchical DEMATEL algorithm and combined with “Wuli-Shili-Renli” methodology suitable for dealing with complex giant system problems. The essential characteristic, verification needs and verification methods of joint operation conception are analyzed, the qualitative evaluation index system of joint operation conception is set up, the analysis framework based on the three-attributes criteria of “Wuli-Shili-Renli” is constructed, and the analysis framework based on the five-dimension criteria of purpose, rationality, feasibility, coordination and risk are built. The case calculation and result analysis are made. Finally，the method is provided for the qualitative verification mode of joint operation conception.
2024, 25(4):58-65.
Abstract:
In view of the fidelity issue of moving target tracking simulation and RCS characteristics, a target tracking and RCS simulation method is proposed based on the improved particle swarm algorithm (PSO). Firstly, the basic principle of simulating the tracking of moving targets is analyzed by unmanned aerial vehicles (UAV), the motion model and coupling relationship between UAVs and simulated targets are discussed, and the coupling factors and control quantities are determined. And then, the constraint conditions for simulating the target tracking are analyzed, and the target optimization fitness function is given in consideration of UAV performance and energy consumption, and an optimal control model is established for simulating the target tracking. To improve the accuracy and practicality of the model solution, the particle swarm optimization algorithm is improved and embedded in the model solution, achieving an effective simulation of the target tracking. Finally, based on the simulated target tracking, the angle of altitude in simulating flight target is calculated through flight dynamics principles and coordinate system transformation, and the RCS of the simulated flight target is simulated by the electromagnetic calculation software. The simulation results show that this method is wide applicable for achieving tracking simulation of moving targets and RCS simulation.
In view of the fidelity issue of moving target tracking simulation and RCS characteristics, a target tracking and RCS simulation method is proposed based on the improved particle swarm algorithm (PSO). Firstly, the basic principle of simulating the tracking of moving targets is analyzed by unmanned aerial vehicles (UAV), the motion model and coupling relationship between UAVs and simulated targets are discussed, and the coupling factors and control quantities are determined. And then, the constraint conditions for simulating the target tracking are analyzed, and the target optimization fitness function is given in consideration of UAV performance and energy consumption, and an optimal control model is established for simulating the target tracking. To improve the accuracy and practicality of the model solution, the particle swarm optimization algorithm is improved and embedded in the model solution, achieving an effective simulation of the target tracking. Finally, based on the simulated target tracking, the angle of altitude in simulating flight target is calculated through flight dynamics principles and coordinate system transformation, and the RCS of the simulated flight target is simulated by the electromagnetic calculation software. The simulation results show that this method is wide applicable for achieving tracking simulation of moving targets and RCS simulation.
2024, 25(4):41-48.
Abstract:
In order to achieve simultaneously excellent multiple moving target imaging quality and imaging efficiency, a SAR multiple moving target imaging method based on alternating direction method of multipliers (ADMM) is proposed by utilizing the multi-component linear frequency modulation signal form and sparse prior knowledge of synthetic aperture radar (SAR) multiple moving target signals, First, a sparse observation model of SAR multiple moving targets is established to formulate the multiple moving target imaging task into an inverse problem with the sparse feature constraint. Then the adaptive Chirplet decomposition method is applied to realize the estimation of target Doppler modulation frequencies for the observation matrix construction. The well-focused SAR image of multiple moving targets can be sparsely reconstructed based on ADMM decomposing the complex convex optimization problem into several simple subproblems which can be alternately solved. Finally, the simulations and the experiments on airborne SAR data show that the proposed method is superior to the existing moving target imaging methods in terms of imaging quality and imaging efficiency.
In order to achieve simultaneously excellent multiple moving target imaging quality and imaging efficiency, a SAR multiple moving target imaging method based on alternating direction method of multipliers (ADMM) is proposed by utilizing the multi-component linear frequency modulation signal form and sparse prior knowledge of synthetic aperture radar (SAR) multiple moving target signals, First, a sparse observation model of SAR multiple moving targets is established to formulate the multiple moving target imaging task into an inverse problem with the sparse feature constraint. Then the adaptive Chirplet decomposition method is applied to realize the estimation of target Doppler modulation frequencies for the observation matrix construction. The well-focused SAR image of multiple moving targets can be sparsely reconstructed based on ADMM decomposing the complex convex optimization problem into several simple subproblems which can be alternately solved. Finally, the simulations and the experiments on airborne SAR data show that the proposed method is superior to the existing moving target imaging methods in terms of imaging quality and imaging efficiency.
2024, 25(4):13-20.
Abstract:
In order to meet the different requirements of aerodynamic performance for Tailless Aerial Vehicle at different flight stages, this paper proposes a multi-objective control allocation method. Firstly, a TAV non-affine rudder effect model is established to mathematically describe the TAV control allocation problem, an incremental nonlinear control allocation method is proposed and its convergence is proved out. And then, the incremental form of the secondary performance indicators. Finally, the multi-objective nonlinear control allocation problem is solved by the effective set quadratic programming method, and simulated for verification. In the simulation scenario of this paper, compared with the minimum rudder deflection case, the average drag coefficient of the minimum drag case is reduced by 36.96%, and the average lift coefficient of the maximum lift case is increased by 7.76%.The experimental results show that the control allocation method can effectively achieve different sub-objectives such as minimum rudder deflection, minimum drag and maximum lift under conditions of minimum moment allocation error.
In order to meet the different requirements of aerodynamic performance for Tailless Aerial Vehicle at different flight stages, this paper proposes a multi-objective control allocation method. Firstly, a TAV non-affine rudder effect model is established to mathematically describe the TAV control allocation problem, an incremental nonlinear control allocation method is proposed and its convergence is proved out. And then, the incremental form of the secondary performance indicators. Finally, the multi-objective nonlinear control allocation problem is solved by the effective set quadratic programming method, and simulated for verification. In the simulation scenario of this paper, compared with the minimum rudder deflection case, the average drag coefficient of the minimum drag case is reduced by 36.96%, and the average lift coefficient of the maximum lift case is increased by 7.76%.The experimental results show that the control allocation method can effectively achieve different sub-objectives such as minimum rudder deflection, minimum drag and maximum lift under conditions of minimum moment allocation error.
2024, 25(4):33-40.
Abstract:
Terahertz scattering characteristic acquisition of targets by radar imaging is an important way of scattering measurement, and its premise is to obtain the high resolution and fine imaging results.Aimed at the problems that measurement of imaging in terahertz radar system is difficult to guarantee a complete consistency between the target center and the turntable center during measurement,and the results of imaging are sensitive to position error of targets for the near field terahertz radar system, in this paper, a corresponding accurate imaging model is deduced and established, a method of distance error compensation based on prior information is presented, and a realization of imaging algorithm is proposed, achieving the target’s high resolution fine image acquisition under condition of near field and large rotation angle. The experimental results show that the proposed imaging method can accurately correct the image distortion and defocus caused by the positioning error and near-field factors of the target, and is not subject to the coincidence of the center of the target coordinate system and the radar coordinate system. The study could pave the way for image-based target scattering feature extraction and scattering center diagnosis in terahertz band.
Terahertz scattering characteristic acquisition of targets by radar imaging is an important way of scattering measurement, and its premise is to obtain the high resolution and fine imaging results.Aimed at the problems that measurement of imaging in terahertz radar system is difficult to guarantee a complete consistency between the target center and the turntable center during measurement,and the results of imaging are sensitive to position error of targets for the near field terahertz radar system, in this paper, a corresponding accurate imaging model is deduced and established, a method of distance error compensation based on prior information is presented, and a realization of imaging algorithm is proposed, achieving the target’s high resolution fine image acquisition under condition of near field and large rotation angle. The experimental results show that the proposed imaging method can accurately correct the image distortion and defocus caused by the positioning error and near-field factors of the target, and is not subject to the coincidence of the center of the target coordinate system and the radar coordinate system. The study could pave the way for image-based target scattering feature extraction and scattering center diagnosis in terahertz band.
9 Simulation Research Based on Gliding Arc Plasma Ignition in a Single Dome Model Combustion Chamber
CHEN Wei
,
CHEN Yi
,
QU Meijiao
,
HU Changhuai
,
ZHU Yifei
,
ZHANG Xiang
,
TANG Chaowei
,
HOU Haohao
2024, 25(4):21-27.
Abstract:
In order to obtain the characteristics of gliding arc plasma ignition in the combustion chamber of aero-engine, the gliding arc plasma ignition simulation of aero-engine single dome model combustor is studied by numerical simulation. The gliding arc plasma is simplified as a dynamic heat source, gliding arc plasma ignition is compared to electric spark ignition, a rule of temperature distribution and flame evolution in combustion chamber is made by the two ignition methods, and the characteristics of gliding arc plasma ignition are summed up. The calculation results show that the average temperature peaks of the two ignition methods are basically the same. For the gliding arc plasma ignition, when the discharge power is 200 W under conditions of air flow being 25 m3/h, the residual air coefficient is 1, and the ignition delay time is 224.6 ms. When the air coefficient is 2, the ignition delay time is 324.9 ms. And when the residual air coefficient is 4, the ignition delay time is 878.7 ms. In addition, when the discharge power is 200 W under conditions of the air coefficient being 1, and the air flow being 15 m3/h, the ignition delay time is 194 8 ms. When the air flow is 35 m3/h, the ignition delay time is 298 9 ms.
In order to obtain the characteristics of gliding arc plasma ignition in the combustion chamber of aero-engine, the gliding arc plasma ignition simulation of aero-engine single dome model combustor is studied by numerical simulation. The gliding arc plasma is simplified as a dynamic heat source, gliding arc plasma ignition is compared to electric spark ignition, a rule of temperature distribution and flame evolution in combustion chamber is made by the two ignition methods, and the characteristics of gliding arc plasma ignition are summed up. The calculation results show that the average temperature peaks of the two ignition methods are basically the same. For the gliding arc plasma ignition, when the discharge power is 200 W under conditions of air flow being 25 m3/h, the residual air coefficient is 1, and the ignition delay time is 224.6 ms. When the air coefficient is 2, the ignition delay time is 324.9 ms. And when the residual air coefficient is 4, the ignition delay time is 878.7 ms. In addition, when the discharge power is 200 W under conditions of the air coefficient being 1, and the air flow being 15 m3/h, the ignition delay time is 194 8 ms. When the air flow is 35 m3/h, the ignition delay time is 298 9 ms.
2024, 25(4):66-71.
Abstract:
In this paper, we propose and implement a time-domain finite integral technique (TDFIT) for modeling thermal deformations and variable structures of any complexity. By employing a rapid 3D interpolation technology, we simultaneously solve the deformation mapping of diverse thermoelectric mesh models and parametric surfaces. Our approach ensures the accurate integrated simulation of thermoelectric properties, arbitrary thermal distributions, and minor shape variations. The proposed method is particularly suitable for materials characterized by electrically large scales, non-uniform temperature changes, and deformations. This study presents a thermoelectric integrated modeling approach and a practical simulation tool for analyzing the electromagnetic scattering and radiation properties of radomes and aircraft under high-temperature and high-pressure conditions.
In this paper, we propose and implement a time-domain finite integral technique (TDFIT) for modeling thermal deformations and variable structures of any complexity. By employing a rapid 3D interpolation technology, we simultaneously solve the deformation mapping of diverse thermoelectric mesh models and parametric surfaces. Our approach ensures the accurate integrated simulation of thermoelectric properties, arbitrary thermal distributions, and minor shape variations. The proposed method is particularly suitable for materials characterized by electrically large scales, non-uniform temperature changes, and deformations. This study presents a thermoelectric integrated modeling approach and a practical simulation tool for analyzing the electromagnetic scattering and radiation properties of radomes and aircraft under high-temperature and high-pressure conditions.
11 Identification Method Based on Binomial Entropy and Van der Waals Forces between Neighboring Nodes
2024, 25(4):72-78.
Abstract:
Ranking importance in nodes is a commonly used analysis method for identifying key nodes in complex networks, and importance of analyzing nodes in the network is a great help to a deeper understanding network characteristics. In order to further improve the accuracy of node evaluation based on existing methods, this paper introduces the concept of Binomial Entropy to quantify the importance of nodes in the network, measures the mutual influence between nodes through neighborhood similarity, and simultaneously uses Van der Waals force to abstract the interaction between nodes. Therefore, a key node identification method based on binomial entropy and Van der Waals force between neighboring nodes is proposed. This method is a comprehensive consideration of the local and global characteristics of nodes from the overall information flow of the network and the location and interaction relationship between adjacent nodes, and a selection from three similar algorithms to verify the performance through three evaluation indicators. The experimental results show that the algorithm in this paper is good in performance in judging important nodes.
Ranking importance in nodes is a commonly used analysis method for identifying key nodes in complex networks, and importance of analyzing nodes in the network is a great help to a deeper understanding network characteristics. In order to further improve the accuracy of node evaluation based on existing methods, this paper introduces the concept of Binomial Entropy to quantify the importance of nodes in the network, measures the mutual influence between nodes through neighborhood similarity, and simultaneously uses Van der Waals force to abstract the interaction between nodes. Therefore, a key node identification method based on binomial entropy and Van der Waals force between neighboring nodes is proposed. This method is a comprehensive consideration of the local and global characteristics of nodes from the overall information flow of the network and the location and interaction relationship between adjacent nodes, and a selection from three similar algorithms to verify the performance through three evaluation indicators. The experimental results show that the algorithm in this paper is good in performance in judging important nodes.
2011(2):57-61.
Abstract:
Atmospheric makes the receiver produce laser power attenuation, light intension scintillant beam excursion phenomenon. The operating performances of the laser communication, laser range finder systems and etc. are seriously limited. Now the commonly used theory and research methods in atmosphere transmission characteristics are all based on the research results of foreign countries. Therefore, the research on atmosphere characteristics in the laser transmission channel is very important and necessary. The theory model of the attenuation effect caused by atmosphere absorption, atmosphere scattering, and the effect model of atmospheric turbulence caused by strong light, drifting and expanding of beam and so on are established. Based on the analysis of the above each model, the simulations are focused on the theory model of atmospheric absorption and scattering, and on the effect model of the atmospheric turbulence on the laser transmission characteristics. The simulation results show that atmospheric absorption and scattering will cause power attenuation. Atmospheric jitter of laser speckles effect, beam bending and expanding will influence the tracking accuracy and precision ship-swaying alignment. The fluctuation of power by atmospheric turbulence will affect communication rate and bit error rate. Finally the research on the laser transmission characteristics in the atmosphere is prospected.
Atmospheric makes the receiver produce laser power attenuation, light intension scintillant beam excursion phenomenon. The operating performances of the laser communication, laser range finder systems and etc. are seriously limited. Now the commonly used theory and research methods in atmosphere transmission characteristics are all based on the research results of foreign countries. Therefore, the research on atmosphere characteristics in the laser transmission channel is very important and necessary. The theory model of the attenuation effect caused by atmosphere absorption, atmosphere scattering, and the effect model of atmospheric turbulence caused by strong light, drifting and expanding of beam and so on are established. Based on the analysis of the above each model, the simulations are focused on the theory model of atmospheric absorption and scattering, and on the effect model of the atmospheric turbulence on the laser transmission characteristics. The simulation results show that atmospheric absorption and scattering will cause power attenuation. Atmospheric jitter of laser speckles effect, beam bending and expanding will influence the tracking accuracy and precision ship-swaying alignment. The fluctuation of power by atmospheric turbulence will affect communication rate and bit error rate. Finally the research on the laser transmission characteristics in the atmosphere is prospected.
2000(1):1-5.
Abstract:
The newest advances m ultrashort pulse laser technology are brief1y revlewed , and the several most lmportant applicatlOns of ultrashort pulse laser , such as ultra-high speed optical commumcatlOn , storage of great capaclty informatlOn , study of photosynthesis and chemical interactlOns by means of femtosecond laser are also discussed.
The newest advances m ultrashort pulse laser technology are brief1y revlewed , and the several most lmportant applicatlOns of ultrashort pulse laser , such as ultra-high speed optical commumcatlOn , storage of great capaclty informatlOn , study of photosynthesis and chemical interactlOns by means of femtosecond laser are also discussed.
2009(1):9-12.
Abstract:
To fulfill the need of computer assistant decision-making and simulating battle drilling, based on the basic helicopter spot performance and a few of original data, the paper makes a model of the Algorithm of rotor's power. By analyzing the characteristics of dynamics and using the momentum theory and blade theory, a computational method of helicopter rotor power and available power is deduced. The rotor power will be respectively calculated as several parts. The pull's calculation model is established with the remnant power by using the linear outer insert method. Finally,a calculated example proves the feasibility of the simplified arithmetic model,thus the problems of flight performance assurance and dynamics simulation are solved.This algorithm is of applied importance.
To fulfill the need of computer assistant decision-making and simulating battle drilling, based on the basic helicopter spot performance and a few of original data, the paper makes a model of the Algorithm of rotor's power. By analyzing the characteristics of dynamics and using the momentum theory and blade theory, a computational method of helicopter rotor power and available power is deduced. The rotor power will be respectively calculated as several parts. The pull's calculation model is established with the remnant power by using the linear outer insert method. Finally,a calculated example proves the feasibility of the simplified arithmetic model,thus the problems of flight performance assurance and dynamics simulation are solved.This algorithm is of applied importance.
2003(1):68-70.
Abstract:
Through demonstrating the influence of discrimination coefficient on grey incidence coefficient in the grey incidence analysis,this paper presents some conclusions defined in selecting discrimination coefficient and the improvement in selecting discrimination coefficient and the improvement in selecting the discrimination coefficient in usual grey incidence analysis literature which is changed from
Through demonstrating the influence of discrimination coefficient on grey incidence coefficient in the grey incidence analysis,this paper presents some conclusions defined in selecting discrimination coefficient and the improvement in selecting discrimination coefficient and the improvement in selecting the discrimination coefficient in usual grey incidence analysis literature which is changed from
2011(6):8-12.
Abstract:
The test capability of AEDC and CIRA icing wind tunnel are analyzed. The present situation of building the icing wind tunnel and that of icing test in China are analyzed. The measurements of the important parameters of liquid water content (LWC) and the water droplets median volume diameter (MVD) are researched. In numerical simulation aspect, four parts of icing numerical calculation are summarized, the virtues and defects of different methods are compared. At last, the development trend of the research for icing on aircraft engine is put forward based on the current research actualities.
The test capability of AEDC and CIRA icing wind tunnel are analyzed. The present situation of building the icing wind tunnel and that of icing test in China are analyzed. The measurements of the important parameters of liquid water content (LWC) and the water droplets median volume diameter (MVD) are researched. In numerical simulation aspect, four parts of icing numerical calculation are summarized, the virtues and defects of different methods are compared. At last, the development trend of the research for icing on aircraft engine is put forward based on the current research actualities.
2010(6):1-6.
Abstract:
Prognostics and health management technology, more advanced than the traditional fault diagnosis technology, is about fault diagnosis, prognostic and health management. It is of great significance in cutting down failure rate and maintenance cost. More and more attention is paid to the reliability of electronic system, especially avionics system. Applying PHM technology to electronic system has been one of the most important trends of PHM technology. Based on the analysis of current research, the four implementation methods of prognostics and health management technology of electronics are summarized. They are monitoring precursors, using canary structures, monitoring environmental and usage loads and integration. Then, the key technologies related to PHM technology of electronics are presented, and the future problems and challenges for PHM technology of electronics in the field of precursors capture, physical degradation model and quality of electronic component are discussed. Finally, several suggestions, about design for testability, standard and estimation of PHM technology, are given for future development of PHM technology of electronics.
Prognostics and health management technology, more advanced than the traditional fault diagnosis technology, is about fault diagnosis, prognostic and health management. It is of great significance in cutting down failure rate and maintenance cost. More and more attention is paid to the reliability of electronic system, especially avionics system. Applying PHM technology to electronic system has been one of the most important trends of PHM technology. Based on the analysis of current research, the four implementation methods of prognostics and health management technology of electronics are summarized. They are monitoring precursors, using canary structures, monitoring environmental and usage loads and integration. Then, the key technologies related to PHM technology of electronics are presented, and the future problems and challenges for PHM technology of electronics in the field of precursors capture, physical degradation model and quality of electronic component are discussed. Finally, several suggestions, about design for testability, standard and estimation of PHM technology, are given for future development of PHM technology of electronics.
2016, 17(4):52-58.
Abstract:
Space backbone network is an integrated network composed by the space-air-ground largescale backbone nodes, and the core of supporting space information network. On the basis of analyzing the status quo of research on space information network of the Europe and the United States of America, space backbone network architecture and protocol framework are proposed according to the relevant characteristics and overall requirements. The network is composed of spacebased network, airbased network, and groundbased network. By so doing, this realizes mutual communication and cooperation through intersatellite links, satelliteair links, satelliteground links, airtoair links, airground links and terrestrial communications lines. The spacebased backbone network based on multilayer satellite network and airbased backbone network based on wireless mesh are mainly studied. Finally, the paper explores the key technologies such as network structure, routing protocols, data transmission technique, heterogeneous compatibility, and network management. This research has some contributions for reference at a certain degree to the construction of future space backbone network.
Space backbone network is an integrated network composed by the space-air-ground largescale backbone nodes, and the core of supporting space information network. On the basis of analyzing the status quo of research on space information network of the Europe and the United States of America, space backbone network architecture and protocol framework are proposed according to the relevant characteristics and overall requirements. The network is composed of spacebased network, airbased network, and groundbased network. By so doing, this realizes mutual communication and cooperation through intersatellite links, satelliteair links, satelliteground links, airtoair links, airground links and terrestrial communications lines. The spacebased backbone network based on multilayer satellite network and airbased backbone network based on wireless mesh are mainly studied. Finally, the paper explores the key technologies such as network structure, routing protocols, data transmission technique, heterogeneous compatibility, and network management. This research has some contributions for reference at a certain degree to the construction of future space backbone network.
2012(4):21-25.
Abstract:
For analyzing the takeoff and landing process of airplane accurately and finding the basis of the runway length design, the differential equations for takeoff and landing running process are established and resolved. The running performance model is built by Simulink program based on the differential equations. The Simulation model is validated to be effective by the contrast in speed and acceleration data, the theoretic results and the simulation results. The running process of the airplane is analyzed by using the model; the results show that the takeoff process and landing process without drogue parachute could be approximately considered as a uniformly accelerated rectilinear motion, the landing process with drogue parachute is relatively complicated. Finally, the affections of three main factors are studied and the results show that the relationships between running length and airfield altitude or wind speed are approximately linear, the relationship between running length and attack angle is nonlinear and the minimum point of running length appears at the attack angle of 8°. The analysis of airplane running state can be taken as basis for runway length and taxiway high speed exit position design.
For analyzing the takeoff and landing process of airplane accurately and finding the basis of the runway length design, the differential equations for takeoff and landing running process are established and resolved. The running performance model is built by Simulink program based on the differential equations. The Simulation model is validated to be effective by the contrast in speed and acceleration data, the theoretic results and the simulation results. The running process of the airplane is analyzed by using the model; the results show that the takeoff process and landing process without drogue parachute could be approximately considered as a uniformly accelerated rectilinear motion, the landing process with drogue parachute is relatively complicated. Finally, the affections of three main factors are studied and the results show that the relationships between running length and airfield altitude or wind speed are approximately linear, the relationship between running length and attack angle is nonlinear and the minimum point of running length appears at the attack angle of 8°. The analysis of airplane running state can be taken as basis for runway length and taxiway high speed exit position design.
2010(5):90-94.
Abstract:
Through strictly proving the equivalence of the least squares method and Gram-Schimdt algorithm in fitting interference wave-front with Zernike polynomials, it is demonstrated that all algorithms of solving Zernike polynomial coefficients in the solving process are the same in stability. That is, when one of these algorithms is interrupted or a mutation appears in fitted interference wave-front in the solving process, then it is also not possible for the other algorithms to fit interference wave-front correctly. The research results show that no algorithm is superior to other algorithms in fitting the interference wave surface with Zernike polynomials. All these algorithms are equivalent in reliability except that their fitting processes are different.
Through strictly proving the equivalence of the least squares method and Gram-Schimdt algorithm in fitting interference wave-front with Zernike polynomials, it is demonstrated that all algorithms of solving Zernike polynomial coefficients in the solving process are the same in stability. That is, when one of these algorithms is interrupted or a mutation appears in fitted interference wave-front in the solving process, then it is also not possible for the other algorithms to fit interference wave-front correctly. The research results show that no algorithm is superior to other algorithms in fitting the interference wave surface with Zernike polynomials. All these algorithms are equivalent in reliability except that their fitting processes are different.
