摘要 :
In view of the characteristics of strong coupling and strong nonlinearity for angle of attack and aiming at the problem of high angle of attack(AOA) control for UAV, the paper designs a high AOA maneuver controller based on Active...
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In view of the characteristics of strong coupling and strong nonlinearity for angle of attack and aiming at the problem of high angle of attack(AOA) control for UAV, the paper designs a high AOA maneuver controller based on Active Disturbance Rejection Control (ADRC). Taking a certain type of unmanned aerial vehicle (UAV) as the control object, based on the method by linear design but by nonlinear using in engineering practice, two sets of linear aircraft models with different characteristics are obtained by selecting one state point of low angle of attack and another state point of high AOA. By ADRC method and engine thrust vector control, a large maneuvering angle of attack controller is designed. It is verified by digital simulation that the controller in this paper has a good control quality compared to PID control method for UAV during flying at high AOA.
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The conception of chirality in physics and chemistry might be merely an academic one if it were not for the stunning fact that most of biochemistry is chiral. Proteins, DNA, amino acid, sugars and many natural products such as ste...
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The conception of chirality in physics and chemistry might be merely an academic one if it were not for the stunning fact that most of biochemistry is chiral. Proteins, DNA, amino acid, sugars and many natural products such as steroids, hormones and pheromones possess chirality. Indeed, classes of molecules such as amino acids are largely found to be homo-chiral. The exact origin of homochirality is one of the great-unanswered questions in evolutionary science. Mechanism and process that lead to transitions from a chiral symmetric state to a totally asymmetric state are thus of general interest. The nucleation of achiral NaClO_3 molecules to form optically chiral crystals is an example of symmetry breaking. The previous researches have been shown that there are some chiral perturbations profoundly to alter the chiral distribution. These include the seeding, the addition of the optically active co-solutes, the chiral beta particles and positrons et al. Although these findings are important for understanding mechanism of the chiral symmetry breaking, there are many opening problems to be resolved. One of the questions is that if an applied force influences the chiral distribution? We become aware of the question and investigated chiral symmetry breaking during growth process of NaClO_3 crystal under DC electric field. This paper will report the experimental results.
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摘要 :
The conception of chirality in physics and chemistry might be merely an academic one if it were not for the stunning fact that most of biochemistry is chiral. Proteins, DNA, amino acid, sugars and many natural products such as ste...
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The conception of chirality in physics and chemistry might be merely an academic one if it were not for the stunning fact that most of biochemistry is chiral. Proteins, DNA, amino acid, sugars and many natural products such as steroids, hormones and pheromones possess chirality. Indeed, classes of molecules such as amino acids are largely found to be homo-chiral. The exact origin of homochirality is one of the great-unanswered questions in evolutionary science. Mechanism and process that lead to transitions from a chiral symmetric state to a totally asymmetric state are thus of general interest. The nucleation of achiral NaClO_3 molecules to form optically chiral crystals is an example of symmetry breaking. The previous researches have been shown that there are some chiral perturbations profoundly to alter the chiral distribution. These include the seeding, the addition of the optically active co-solutes, the chiral beta particles and positrons et al. Although these findings are important for understanding mechanism of the chiral symmetry breaking, there are many opening problems to be resolved. One of the questions is that if an applied force influences the chiral distribution? We become aware of the question and investigated chiral symmetry breaking during growth process of NaClO_3 crystal under DC electric field. This paper will report the experimental results.
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摘要 :
A set of nucleation experiments on α-LiIO_3 crystal from aqueous solution has been completed in space and on the ground. Preliminary results from α-LiIO_3 study promoted us to consider the problem of asymmetric synthesis. The cr...
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A set of nucleation experiments on α-LiIO_3 crystal from aqueous solution has been completed in space and on the ground. Preliminary results from α-LiIO_3 study promoted us to consider the problem of asymmetric synthesis. The crystals of NaClO_3 were adopted for investigated the role of convection during process of asymmetric synthesis of crystal on the ground. More than 1000 of α-LiIO_3 and 15,000 small NaClO_3 crystals were grown. The probability distribution function (PDF) of 1- and d-handed crystals has been presented. The nucleation mechanism is progressing by PDF data. The fluid convection might pay an important role during process of asymmetric synthesis of crystal. It was found that the pH value in solution could be influenced the crystal chirality of NaClO_3, but the effect is weak if it is comparison with stirring perturbations.
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摘要 :
A set of nucleation experiments on α-LiIO_3 crystal from aqueous solution has been completed in space and on the ground. Preliminary results from α-LiIO_3 study promoted us to consider the problem of asymmetric synthesis. The cr...
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A set of nucleation experiments on α-LiIO_3 crystal from aqueous solution has been completed in space and on the ground. Preliminary results from α-LiIO_3 study promoted us to consider the problem of asymmetric synthesis. The crystals of NaClO_3 were adopted for investigated the role of convection during process of asymmetric synthesis of crystal on the ground. More than 1000 of α-LiIO_3 and 15,000 small NaClO_3 crystals were grown. The probability distribution function (PDF) of 1- and d-handed crystals has been presented. The nucleation mechanism is progressing by PDF data. The fluid convection might pay an important role during process of asymmetric synthesis of crystal. It was found that the pH value in solution could be influenced the crystal chirality of NaClO_3, but the effect is weak if it is comparison with stirring perturbations.
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The research way is discussed in this paper is to use digital image processing technology to measure the coordinates (x0, y0), the radius distribution for industrial product with cylinder Holes, as well as the machining dimension ...
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The research way is discussed in this paper is to use digital image processing technology to measure the coordinates (x0, y0), the radius distribution for industrial product with cylinder Holes, as well as the machining dimension error which forms as a result of all sorts of disturbances in machining course, as the small eccentricity, the ellipticity, three side prism, four side prism and so on, by this we can also find a just way to improve the numerical control machining precision.
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摘要 :
The research way is discussed in this paper is to use digital image processing technology to measure the coordinates (x0, y0), the radius distribution for industrial product with cylinder Holes, as well as the machining dimension ...
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The research way is discussed in this paper is to use digital image processing technology to measure the coordinates (x0, y0), the radius distribution for industrial product with cylinder Holes, as well as the machining dimension error which forms as a result of all sorts of disturbances in machining course, as the small eccentricity, the ellipticity, three side prism, four side prism and so on, by this we can also find a just way to improve the numerical control machining precision.
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Presents two reaching laws of sliding mode for discrete-time variable structure control systems to solve the problem in designing the system control input. Considering the system control input is restricted, the reaching laws prop...
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Presents two reaching laws of sliding mode for discrete-time variable structure control systems to solve the problem in designing the system control input. Considering the system control input is restricted, the reaching laws proposed in this paper adopt the approach angle and the distance to the sliding surface to regulate the system control input properly. By applying the proposed reaching laws of sliding mode to discrete-time variable structure control systems, the stability of the origin can be ensured, the dynamic performance of the system movement is improved. Finally two simulation examples are given to show the effectiveness of the two reaching laws proposed.
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In view of the fact that single mode auto-drilling can not meet the requirements of different targets and different drilling stages for automatic drilling, several kinds of auto-drilling technology in multi-mode are studied, inclu...
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In view of the fact that single mode auto-drilling can not meet the requirements of different targets and different drilling stages for automatic drilling, several kinds of auto-drilling technology in multi-mode are studied, including constant rate of penetration (ROP) control, constant weight on bit (WOB) control, constant pump pressure control, constant power control and constant torque control, and corresponding auto-drilling control systems are constructed respectively. In view of the complexity of drilling process and the difficulty in establishing mathematical model, the active disturbance rejection control (ADRC) strategy is proposed after analyzing the relationship among various factors affecting the drilling. The algorithm does not need the precise mathematical model of the control object, and can modify the control parameters in real time through self-learning. The experiment results show that the control effect is good, the auto-drilling can be realized on the basis of multi-mode target, and the control algorithm is also universal.
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摘要 :
In view of the fact that single mode auto-drilling can not meet the requirements of different targets and different drilling stages for automatic drilling, several kinds of auto-drilling technology in multi-mode are studied, inclu...
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In view of the fact that single mode auto-drilling can not meet the requirements of different targets and different drilling stages for automatic drilling, several kinds of auto-drilling technology in multi-mode are studied, including constant rate of penetration (ROP) control, constant weight on bit (WOB) control, constant pump pressure control, constant power control and constant torque control, and corresponding auto-drilling control systems are constructed respectively. In view of the complexity of drilling process and the difficulty in establishing mathematical model, the active disturbance rejection control (ADRC) strategy is proposed after analyzing the relationship among various factors affecting the drilling. The algorithm does not need the precise mathematical model of the control object, and can modify the control parameters in real time through self-learning. The experiment results show that the control effect is good, the auto-drilling can be realized on the basis of multi-mode target, and the control algorithm is also universal.
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