The miniature design technology is an important trend in space exploration.Mass spectrometer is used extensively in the space environment detection.The miniature ion mass spectrometer utilizes a 127° cylindrical ...The miniature design technology is an important trend in space exploration.Mass spectrometer is used extensively in the space environment detection.The miniature ion mass spectrometer utilizes a 127° cylindrical electrostatic analyzer accompanied with a Time of Flight(TOF)unit based on ultrathin carbon foil to measure the energy spectra and composition of space plasma.The Time of Flight technique has been used broadly in space plasma measurement.A new type of miniature method for the ion mass spectrometer is introduced.The total mass of the instrument is1.8 kg and the total power consumption is 2.0 W.The calibration results show that the energy measurement range is 8.71~43550eV,the energy resolution is 1.86%and the ion mass from 1 amu(1 amu= 1.67 × 10^(-27)kg) to 58 amu can be resolved by the miniature mass spectrometer.The miniature ion mass spectrometer also has a potential to be increased in the field of view by an electrostatic deflecting system to extend its application in space plasma detection.The miniature ion mass spectrometer has been selected for pre-study of Chinese Strategic Priority Research Program on Space Science.展开更多
A novel space-borne antenna adaptive anti-jamming method based on the genetic algorithm (GA), which is combined with gradient-like reproduction operators is presented, to search for the best weight for pattern synth...A novel space-borne antenna adaptive anti-jamming method based on the genetic algorithm (GA), which is combined with gradient-like reproduction operators is presented, to search for the best weight for pattern synthesis in radio frequency (RF). Combined, the GA's the capability of the whole searching is, but not limited by selection of the initial parameter, with the gradient algorithm's advantage of fast searching. The proposed method requires a smaller sized initial population and lower computational complexity. Therefore, it is flexible to implement this method in the real-time systems. By using the proposed algorithm, the designer can efficiently control both main-lobe shaping and side-lobe level. Simulation results based on the spot survey data show that the algorithm proposed is efficient and feasible.展开更多
A new way is proposed to evaluate the influence of atmospheric turbulence on image resolution of airborne and space-borne optical remote sensing system, which is called as arrival angle-method. Applying this method, s...A new way is proposed to evaluate the influence of atmospheric turbulence on image resolution of airborne and space-borne optical remote sensing system, which is called as arrival angle-method. Applying this method, some engineering examples are selected to analyze the turbulence influences on image resolution based on three different atmospheric turbulence models quantificationally, for the airborne remote sensing system, the resolution errors caused by the atmospheric turbulence are less than 1 cm, and for the space-borne remote sensing system, the errors are around 1 cm. The results are similar to that obtained by the previous Friedmethod. Compared with the Fried-method, the arrival angle-method is rather simple and can be easily used in engineering fields.展开更多
To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky,a study on space luminous environment adaptability of missile-borne star sensor was carried out.By ...To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky,a study on space luminous environment adaptability of missile-borne star sensor was carried out.By Plank blackbody radiation law and some astronomic knowledge,irradiancies of the stray at the star sensor working height were estimated.By relative astrophysical and mathematics knowledge,included angles between the star sensor optical axis point and the stray at any moment were calculated.The calculation correctness was verified with the star map software of Stellarium.By combining the upper analysis with the baffle suppression effect,a real-time model for space luminous environment of missile-borne star sensor was proposed.By signal-noise rate(SNR)criterion,the adaptability of missile-borne star sensor to space luminous environment was studied.As an example,a certain type of star sensor was considered when imaging to the starry sky on June 22,2011(the Summer Solstice)and September 20,2011(August 23 of the lunar year,last quarter moon)in Beijing.The space luminous environment and the adaptability to it were simulated and analyzed at the star sensor working height.In each period of time,the stray suppression of the baffle is analyzed by comparing the calculated included angle between the star sensor optical axis point and the stray with the shielded provided by system index.When the included angle is larger than the shielded angle and less than 90°,the stray is restrained by the baffle.The stray effect on star point target identification is analyzed by comparing the irradiancy of 6 magnitude star with that of the stray on star sensor sensitization surface.When the irradiancy of 6 magnitude star is 5 times more than that of the stray,there is no effect on the star point target identification.The simulation results are identical with the actual situation.The space luminous environment of the missile-borne star sensor can be estimated real-timely by this model.The adaptability of the star sensor to space luminous environment can be analyzed conveniently.A basis for determining the relative star sensor indexes,the navigation star chosen strategy and the missile launch window can be provided.展开更多
Large range cell migration is a severe challenge to imaging algorithm for spaceborne SAR. Based on design of Finite Impulse Response (FIR) filter and Range Doppler (RD) algorithm,a realization of quick-look imaging fo...Large range cell migration is a severe challenge to imaging algorithm for spaceborne SAR. Based on design of Finite Impulse Response (FIR) filter and Range Doppler (RD) algorithm,a realization of quick-look imaging for large range cell migration is proposed. It realized quicklook imaging of 8 times reduced resolution with parallel processing on memory shared 8 CPU SGI server. According to simulation experiment, this quick-look imaging algorithm with parallel processing can image 16384× 16384 SAR raw data within 6 seconds. It reaches the requirement of real-time imaging.展开更多
Aiming at the potential presence of mixing automatic identification system(AIS) signals,a new demodulation scheme was proposed for separating other interfering signals in satellite systems.The combined iterative cross...Aiming at the potential presence of mixing automatic identification system(AIS) signals,a new demodulation scheme was proposed for separating other interfering signals in satellite systems.The combined iterative cross-correlation demodulation scheme,referred to as CICCD,yielded a set of single short signals based on the prior information of AIS,after the frequency,code rate and modulation index were estimated.It demodulates the corresponding short codes according to the maximum peak of cross-correlation,which is simple and easy to implement.Numerical simulations show that the bit error rate of proposed algorithm improves by about 40% compared with existing ones,and about 3 dB beyond the standard AIS receiver.In addition,the proposed demodulation scheme shows the satisfying performance and engineering value in mixing AIS environment and can also perform well in low signal-to-noise conditions.展开更多
The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technolog...The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technologies suitable for the wind lidar measurement from an orbital platform become mature. However, there are still some problems to be solved. In order to obtain the optimal performance in wind detection, great importance is being attached to the simulation of a virtual space-borne wind lidar system on computer as developed by NASA and ESA.展开更多
A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of contro...A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the po- sition and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane's equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters be- ing estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov's method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach.展开更多
Modifications of the Weyl-Heisenberg algebra are proposed where the classical limit corresponds to a metric in (curved) momentum spaces. In the simplest scenario, the 2D de Sitter metric of constant curvature in momen...Modifications of the Weyl-Heisenberg algebra are proposed where the classical limit corresponds to a metric in (curved) momentum spaces. In the simplest scenario, the 2D de Sitter metric of constant curvature in momentum space furnishes a hierarchy of modified uncertainty relations leading to a minimum value for the position uncertainty . The first uncertainty relation of this hierarchy has the same functional form as the stringy modified uncertainty relation with a Planck scale minimum value for at . We proceed with a discussion of the most general curved phase space scenario (cotangent bundle of spacetime) and provide the noncommuting phase space coordinates algebra in terms of the symmetric and nonsymmetric metric components of a Hermitian complex metric , such . Yang’s noncommuting phase-space coordinates algebra, combined with the Schrodinger-Robertson inequalities involving angular momentum eigenstates, reveals how a quantized area operator in units of emerges like it occurs in Loop Quantum Gravity (LQG). Some final comments are made about Fedosov deformation quantization, Noncommutative and Nonassociative gravity.展开更多
A novel approach to design Internal Model Controller(IMC)is proposed in this paper directly from measuredinput and output plant data,which are assumed to becontaminated by measurement noise.In order to avoidthe compli...A novel approach to design Internal Model Controller(IMC)is proposed in this paper directly from measuredinput and output plant data,which are assumed to becontaminated by measurement noise.In order to avoidthe complicated structure-identification problem inmost cases,two Finite Impulse Response(FIR)modelsare taken to represent the plant model and the internalmodel controller respectively.Taking account of mea-surement noise both in the plant input and its output,anESD based Total Least Squares(TLS)solution is appliedfor the unbiased identification of the plant model and itsinverse model,the latter constitutes the internal modelcontroller according to the principle that the internalmodel controller approximates the inverse dynamics ofthe plant model.Simulations are given for a testifica-tion.展开更多
使用热带测雨卫星(TRMM)搭载的测雨雷达(PR)2004—2014年长达11a的连续观测资料对青藏高原东南缘川渝地区不同季节不同降水类型的垂直结构特征进行了统计分析,并建立了相应的气候态反射率垂直廓线(Vertical Profiles of Reflectivity,简...使用热带测雨卫星(TRMM)搭载的测雨雷达(PR)2004—2014年长达11a的连续观测资料对青藏高原东南缘川渝地区不同季节不同降水类型的垂直结构特征进行了统计分析,并建立了相应的气候态反射率垂直廓线(Vertical Profiles of Reflectivity,简称VPR)。结果表明,由于不同的微物理及动力过程,降水类型对反射率垂直廓线的结构特征影响很大,90%的层云0℃层亮带峰值强度低于32dBz,50%的对流云最大反射率强度超过35dBz。降水类型及强度均对反射率垂直廓线的形状影响很大,层云系统发生中及大雨时其冰雪区的聚合反应效率明显较发生小雨时高。反射率垂直廓线特征参数具有一定的区域性和季节特征,且地表加热和地形高度的作用会加强上升气流对反射率垂直廓线形态的影响,上升气流的强度影响着冰雪及雨水区的碰并增长率以及低层的蒸发作用,从而进一步影响低层雨区的反射率垂直廓线斜率,边界层的相对湿度是另一个影响雨区反射率垂直廓线斜率及蒸发率的重要因素。星载测雨雷达的云分类算法在青藏高原东南缘地区受到一定的挑战,仍有改进的空间;未来可以将基于星载测雨雷达建立气候态层云典型反射率垂直廓线应用于联合地基天气雷达网观测以弥补后者在复杂地形条件下探测范围及能力受限的缺陷,从而改进雷达定量降水估测的误差。展开更多
遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near In...遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near Infra-red)、SWIR(Short wave-length Infra-red)、TIR(Thermal Infra-red)]、波段多(14个波段)、性价比合理等因素,ASTER数据的研究迅速发展。长久以来,对覆盖区进行蚀变遥感异常信息提取一直是遥感找矿的关注点之一。笔者等利用ASTER数据对浅覆盖区——包古图斑岩铜矿的Ⅱ号、Ⅴ号斑岩体进行蚀变遥感异常提取,提取的蚀变异常与野外地质情况吻合性好。分别提取了光谱特征谱带差异明显的2组蚀变矿物的异常信息:第一组是蒙脱石、埃洛石、伊利石与绢云母;第二组是方解石、黑云母与绿泥石。提出了需要进一步工作的异常靶区。展开更多
基金Supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(XDA04071700,XDA04060202)
文摘The miniature design technology is an important trend in space exploration.Mass spectrometer is used extensively in the space environment detection.The miniature ion mass spectrometer utilizes a 127° cylindrical electrostatic analyzer accompanied with a Time of Flight(TOF)unit based on ultrathin carbon foil to measure the energy spectra and composition of space plasma.The Time of Flight technique has been used broadly in space plasma measurement.A new type of miniature method for the ion mass spectrometer is introduced.The total mass of the instrument is1.8 kg and the total power consumption is 2.0 W.The calibration results show that the energy measurement range is 8.71~43550eV,the energy resolution is 1.86%and the ion mass from 1 amu(1 amu= 1.67 × 10^(-27)kg) to 58 amu can be resolved by the miniature mass spectrometer.The miniature ion mass spectrometer also has a potential to be increased in the field of view by an electrostatic deflecting system to extend its application in space plasma detection.The miniature ion mass spectrometer has been selected for pre-study of Chinese Strategic Priority Research Program on Space Science.
基金the National Natural Science Foundation of China (60502045).
文摘A novel space-borne antenna adaptive anti-jamming method based on the genetic algorithm (GA), which is combined with gradient-like reproduction operators is presented, to search for the best weight for pattern synthesis in radio frequency (RF). Combined, the GA's the capability of the whole searching is, but not limited by selection of the initial parameter, with the gradient algorithm's advantage of fast searching. The proposed method requires a smaller sized initial population and lower computational complexity. Therefore, it is flexible to implement this method in the real-time systems. By using the proposed algorithm, the designer can efficiently control both main-lobe shaping and side-lobe level. Simulation results based on the spot survey data show that the algorithm proposed is efficient and feasible.
文摘A new way is proposed to evaluate the influence of atmospheric turbulence on image resolution of airborne and space-borne optical remote sensing system, which is called as arrival angle-method. Applying this method, some engineering examples are selected to analyze the turbulence influences on image resolution based on three different atmospheric turbulence models quantificationally, for the airborne remote sensing system, the resolution errors caused by the atmospheric turbulence are less than 1 cm, and for the space-borne remote sensing system, the errors are around 1 cm. The results are similar to that obtained by the previous Friedmethod. Compared with the Fried-method, the arrival angle-method is rather simple and can be easily used in engineering fields.
文摘To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky,a study on space luminous environment adaptability of missile-borne star sensor was carried out.By Plank blackbody radiation law and some astronomic knowledge,irradiancies of the stray at the star sensor working height were estimated.By relative astrophysical and mathematics knowledge,included angles between the star sensor optical axis point and the stray at any moment were calculated.The calculation correctness was verified with the star map software of Stellarium.By combining the upper analysis with the baffle suppression effect,a real-time model for space luminous environment of missile-borne star sensor was proposed.By signal-noise rate(SNR)criterion,the adaptability of missile-borne star sensor to space luminous environment was studied.As an example,a certain type of star sensor was considered when imaging to the starry sky on June 22,2011(the Summer Solstice)and September 20,2011(August 23 of the lunar year,last quarter moon)in Beijing.The space luminous environment and the adaptability to it were simulated and analyzed at the star sensor working height.In each period of time,the stray suppression of the baffle is analyzed by comparing the calculated included angle between the star sensor optical axis point and the stray with the shielded provided by system index.When the included angle is larger than the shielded angle and less than 90°,the stray is restrained by the baffle.The stray effect on star point target identification is analyzed by comparing the irradiancy of 6 magnitude star with that of the stray on star sensor sensitization surface.When the irradiancy of 6 magnitude star is 5 times more than that of the stray,there is no effect on the star point target identification.The simulation results are identical with the actual situation.The space luminous environment of the missile-borne star sensor can be estimated real-timely by this model.The adaptability of the star sensor to space luminous environment can be analyzed conveniently.A basis for determining the relative star sensor indexes,the navigation star chosen strategy and the missile launch window can be provided.
文摘Large range cell migration is a severe challenge to imaging algorithm for spaceborne SAR. Based on design of Finite Impulse Response (FIR) filter and Range Doppler (RD) algorithm,a realization of quick-look imaging for large range cell migration is proposed. It realized quicklook imaging of 8 times reduced resolution with parallel processing on memory shared 8 CPU SGI server. According to simulation experiment, this quick-look imaging algorithm with parallel processing can image 16384× 16384 SAR raw data within 6 seconds. It reaches the requirement of real-time imaging.
基金Project(9140C860304) supported by the National Defense Key Laboratory Foundation of China
文摘Aiming at the potential presence of mixing automatic identification system(AIS) signals,a new demodulation scheme was proposed for separating other interfering signals in satellite systems.The combined iterative cross-correlation demodulation scheme,referred to as CICCD,yielded a set of single short signals based on the prior information of AIS,after the frequency,code rate and modulation index were estimated.It demodulates the corresponding short codes according to the maximum peak of cross-correlation,which is simple and easy to implement.Numerical simulations show that the bit error rate of proposed algorithm improves by about 40% compared with existing ones,and about 3 dB beyond the standard AIS receiver.In addition,the proposed demodulation scheme shows the satisfying performance and engineering value in mixing AIS environment and can also perform well in low signal-to-noise conditions.
基金supported by National High Tech 863 Project(No.2002AA135280)National Natural Science Foundation of China No.40176011International Bureau of BMBF
文摘The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technologies suitable for the wind lidar measurement from an orbital platform become mature. However, there are still some problems to be solved. In order to obtain the optimal performance in wind detection, great importance is being attached to the simulation of a virtual space-borne wind lidar system on computer as developed by NASA and ESA.
基金supported by the National Natural Science Foundation of China(11272027)
文摘A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the po- sition and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane's equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters be- ing estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov's method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach.
文摘Modifications of the Weyl-Heisenberg algebra are proposed where the classical limit corresponds to a metric in (curved) momentum spaces. In the simplest scenario, the 2D de Sitter metric of constant curvature in momentum space furnishes a hierarchy of modified uncertainty relations leading to a minimum value for the position uncertainty . The first uncertainty relation of this hierarchy has the same functional form as the stringy modified uncertainty relation with a Planck scale minimum value for at . We proceed with a discussion of the most general curved phase space scenario (cotangent bundle of spacetime) and provide the noncommuting phase space coordinates algebra in terms of the symmetric and nonsymmetric metric components of a Hermitian complex metric , such . Yang’s noncommuting phase-space coordinates algebra, combined with the Schrodinger-Robertson inequalities involving angular momentum eigenstates, reveals how a quantized area operator in units of emerges like it occurs in Loop Quantum Gravity (LQG). Some final comments are made about Fedosov deformation quantization, Noncommutative and Nonassociative gravity.
文摘A novel approach to design Internal Model Controller(IMC)is proposed in this paper directly from measuredinput and output plant data,which are assumed to becontaminated by measurement noise.In order to avoidthe complicated structure-identification problem inmost cases,two Finite Impulse Response(FIR)modelsare taken to represent the plant model and the internalmodel controller respectively.Taking account of mea-surement noise both in the plant input and its output,anESD based Total Least Squares(TLS)solution is appliedfor the unbiased identification of the plant model and itsinverse model,the latter constitutes the internal modelcontroller according to the principle that the internalmodel controller approximates the inverse dynamics ofthe plant model.Simulations are given for a testifica-tion.
文摘使用热带测雨卫星(TRMM)搭载的测雨雷达(PR)2004—2014年长达11a的连续观测资料对青藏高原东南缘川渝地区不同季节不同降水类型的垂直结构特征进行了统计分析,并建立了相应的气候态反射率垂直廓线(Vertical Profiles of Reflectivity,简称VPR)。结果表明,由于不同的微物理及动力过程,降水类型对反射率垂直廓线的结构特征影响很大,90%的层云0℃层亮带峰值强度低于32dBz,50%的对流云最大反射率强度超过35dBz。降水类型及强度均对反射率垂直廓线的形状影响很大,层云系统发生中及大雨时其冰雪区的聚合反应效率明显较发生小雨时高。反射率垂直廓线特征参数具有一定的区域性和季节特征,且地表加热和地形高度的作用会加强上升气流对反射率垂直廓线形态的影响,上升气流的强度影响着冰雪及雨水区的碰并增长率以及低层的蒸发作用,从而进一步影响低层雨区的反射率垂直廓线斜率,边界层的相对湿度是另一个影响雨区反射率垂直廓线斜率及蒸发率的重要因素。星载测雨雷达的云分类算法在青藏高原东南缘地区受到一定的挑战,仍有改进的空间;未来可以将基于星载测雨雷达建立气候态层云典型反射率垂直廓线应用于联合地基天气雷达网观测以弥补后者在复杂地形条件下探测范围及能力受限的缺陷,从而改进雷达定量降水估测的误差。
文摘遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near Infra-red)、SWIR(Short wave-length Infra-red)、TIR(Thermal Infra-red)]、波段多(14个波段)、性价比合理等因素,ASTER数据的研究迅速发展。长久以来,对覆盖区进行蚀变遥感异常信息提取一直是遥感找矿的关注点之一。笔者等利用ASTER数据对浅覆盖区——包古图斑岩铜矿的Ⅱ号、Ⅴ号斑岩体进行蚀变遥感异常提取,提取的蚀变异常与野外地质情况吻合性好。分别提取了光谱特征谱带差异明显的2组蚀变矿物的异常信息:第一组是蒙脱石、埃洛石、伊利石与绢云母;第二组是方解石、黑云母与绿泥石。提出了需要进一步工作的异常靶区。