The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and freque...The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and frequency of the wireless signal between different receivers.Therefore,ground monitoring stations need to be equipped with more than two antenna receiving stations,and multiple satellites should be able to simultaneously relay the distress signal from the target source in order to achieve the geolocation function.However,when the ground receiving system has only one antenna receiving station,or the target source is in a heavily obscured environment,the ground side is unable to receive the forwarded signals from multiple satellites at the same time,which will make it impossible to locate.To address these problems,in this paper,a time-sharing single satellite geolocations method based on different orbits is proposed for the first time.This method uses one or several low-earth orbit satellites(LEO)and mediumearth orbit satellites(MEO)in the visible area,and the receiving station only needs one pair of receiving antennas to complete the positioning.It can effectively compensate for the shortcomings of the traditional TDOA using the same moment and have better positioning accuracy compared with the single satellite in the same orbit.Due to the limited experimental conditions,this paper tests the navigation satellite using different orbit time-sharing single satellite geolocations,and proves that the positioning method has high positioning accuracy and has certain promotion and application value.展开更多
A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze.This method is used to estimate the mixing coefficients of de-noised signals thro...A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze.This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals,solve the candidate data set by the mixing coefficients and signal analytical form,and resolve the problem of vector ambiguity by analyzing the phase differences.The signal separation is realized by exchanging data of the solutions.The waveform similarity coefficients are calculated,and the time鈥攆requency distributions of separated signals are analyzed.The results show that the proposed method is effective.展开更多
Considering the temperature difference of displacement cooking characterized by severe non-linearity, large time delay, and real-time control, a cascade PID adaptive control strategy composed of a single neuron is pro...Considering the temperature difference of displacement cooking characterized by severe non-linearity, large time delay, and real-time control, a cascade PID adaptive control strategy composed of a single neuron is proposed to ensure cooking temperature uniformity. The control strategy introduces expert experiences to adjust the single neuron gain K, while a single neuron PID self-learning and adaptive ability, as well as cascade advantage can be combined to realize the real-time and fast temperature difference control. In the Simulink, the s-function of this control strategy is used to carry out a dynamic simulation experiment with temperature difference characteristics and verify the robustness and response to model mismatch. Compared to conventional temperature difference-flow PID cascade control and single neuron PID cascade control, this control strategy has better robustness and stronger adaptability. The results of real-time control on the THJSK-1 experiment platform indicate this control strategy is feasible.展开更多
Using similar single-difference methodology(SSDM) to solve the deformation values of the monitoring points, there is unstability of the deformation information series, at sometimes.In order to overcome this shortcomin...Using similar single-difference methodology(SSDM) to solve the deformation values of the monitoring points, there is unstability of the deformation information series, at sometimes.In order to overcome this shortcoming, Kalman filtering algorithm for this series is established,and its correctness and validity are verified with the test data obtained on the movable platform in plane. The results show that Kalman filtering can improve the correctness, reliability and stability of the deformation information series.展开更多
This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency sh...This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency shift and path difference,the virtual path difference is calculated from the measured value of Doppler frequency shift by means of mean value correction.Then,under the assumption that the target is moving at a constant speed along a straight line,two coaxial virtual double base arrays are constructed by using the moving track of the moving target based on the method of fixed period time difference.On this basis,the moving distance of the moving target can be calculated by using the ratio relationship between the frequency difference and the radial distance between the two adjacent detection points in the middle of the array,and the linear solution of the two double base path difference positioning equations.At this point,the relative coordinate position of the moving target can be obtained by directly using the linear solution of the double base path difference positioning equation again.展开更多
[Objective] The aim was to explore the reasons of false positives in Different Display Reverse Transcription(DDRT)analysis.[Method] Soybean varieties "Jilin 30" and "Tongnong 13" were used as materials to carry ...[Objective] The aim was to explore the reasons of false positives in Different Display Reverse Transcription(DDRT)analysis.[Method] Soybean varieties "Jilin 30" and "Tongnong 13" were used as materials to carry out analysis on false positives in DDRT analysis.[Result] An important origin of false positives appeared in DDRT analysis was the non-specific amplification caused by the combination of single primer and cDNA.The parallel PCR test of single primer should be set so as to verify whether the obtained fragments were the false positives or the PCR productions combined with single primer.[Conclusion] This study had provided basis for improving the success rate of DDRT experiment.展开更多
The advancement of small satellites is promoting the development of distributed satellite systems,and for the latter,it is essential to coordinate the spatial and temporal relations between mutually visible satellites...The advancement of small satellites is promoting the development of distributed satellite systems,and for the latter,it is essential to coordinate the spatial and temporal relations between mutually visible satellites.By now,dual one-way ranging(DOWR)and two-way time transfer(TWTT)are generally integrated in the same software and hardware system to meet the limitations of small satellites in terms of size,weight and power(SWaP)consumption.However,studies show that pseudo-noise regenerative ranging(PNRR)performs better than DOWR if some advanced implementation technologies are employed.Besides,PNRR has no requirement on time synchronization.To apply PNRR to small satellites,and meanwhile,meet the demand for time difference measurement,we propose the round-way time difference measurement,which can be combined with PNRR to form a new integrated system without exceeding the limits of SWaP.The new integrated system can provide distributed small satellite systems with on-orbit high-accuracy and high-precision distance measurement and time difference measurement in real time.Experimental results show that the precision of ranging is about 1.94 cm,and that of time difference measurement is about 78.4 ps,at the signal to noise ratio of 80 dBHz.展开更多
An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved....An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved. These potentials were clarified with some experimental extraction-data reported before on the M = Ag(I), Ca(II), Sr(II) and Ba(II) extraction with 18-crown-6 ether (18C6) and benzo-18C6 into 1,2-dichloroethane (DCE) and nitrobenzene (NB). Consequently, it was demonstrated that the? values from the extraction-experimentally obtained logKD,Pic ones are in agreement with or close to those calculated from charge balance equations in many cases, where the symbol, KD,Pic, denotes an individual distribution constant of Pic﹣ into the DCE or NB phase. Also, it was experimentally shown that extraction constants based on the overall extraction equilibria do not virtually contain the? terms in their functional expressions.展开更多
不对称接地故障占所有线路故障的90%以上,接地距离保护在应对此类故障方面发挥了不可替代的作用。随着新能源高比例渗透,各种传统单端工频量保护性能显著下降已成为共识。基于故障分量线模和零模波速差的保护判据理论上仅需利用到故障...不对称接地故障占所有线路故障的90%以上,接地距离保护在应对此类故障方面发挥了不可替代的作用。随着新能源高比例渗透,各种传统单端工频量保护性能显著下降已成为共识。基于故障分量线模和零模波速差的保护判据理论上仅需利用到故障初始行波到达时刻信息,是一种原理简单可靠的单端量快速保护判据,已经在直流电网中成功实践。但在尝试将这类保护应用于交流电网时发现,受波头前陡较缓而难以精确定位波到时刻、依赖高采样率等诸多不利因素影响,存在过大的模糊判别区,除了特长线路外,对绝大部分线路几乎没有应用可行性。波到时刻的精准辨识是一个复杂的非线性问题,利用人工智能的方法进行辨识是一条可行的解决思路,对此,该文提出一种新的单端暂态量主保护判据。首先,分析波达时刻与波形关系,并指出这种关系能够采用机器学习来映射;其次,引入高斯过程回归(Gaussian process regression,GPR),在对初始行波数据进行预处理得到样本集后,输入GPR预测模型进行训练;然后,依据模型评估指标得到最优训练模型以输出高可信性的线-零模波达时差,据此实现了基于行波模量传输时间差的保护判据;最后,在利用PSCAD仿真验证所提保护判据有效性和普适性的基础上,进一步利用现场实测数据对判据进行测试,验证其实用性。该文工作为新能源交流系统下单端暂态量保护的性能提升提供新的解决思路。展开更多
基金supported by National Science Foundation of China(No.91738201,U21A20450)。
文摘The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and frequency of the wireless signal between different receivers.Therefore,ground monitoring stations need to be equipped with more than two antenna receiving stations,and multiple satellites should be able to simultaneously relay the distress signal from the target source in order to achieve the geolocation function.However,when the ground receiving system has only one antenna receiving station,or the target source is in a heavily obscured environment,the ground side is unable to receive the forwarded signals from multiple satellites at the same time,which will make it impossible to locate.To address these problems,in this paper,a time-sharing single satellite geolocations method based on different orbits is proposed for the first time.This method uses one or several low-earth orbit satellites(LEO)and mediumearth orbit satellites(MEO)in the visible area,and the receiving station only needs one pair of receiving antennas to complete the positioning.It can effectively compensate for the shortcomings of the traditional TDOA using the same moment and have better positioning accuracy compared with the single satellite in the same orbit.Due to the limited experimental conditions,this paper tests the navigation satellite using different orbit time-sharing single satellite geolocations,and proves that the positioning method has high positioning accuracy and has certain promotion and application value.
文摘A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze.This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals,solve the candidate data set by the mixing coefficients and signal analytical form,and resolve the problem of vector ambiguity by analyzing the phase differences.The signal separation is realized by exchanging data of the solutions.The waveform similarity coefficients are calculated,and the time鈥攆requency distributions of separated signals are analyzed.The results show that the proposed method is effective.
文摘Considering the temperature difference of displacement cooking characterized by severe non-linearity, large time delay, and real-time control, a cascade PID adaptive control strategy composed of a single neuron is proposed to ensure cooking temperature uniformity. The control strategy introduces expert experiences to adjust the single neuron gain K, while a single neuron PID self-learning and adaptive ability, as well as cascade advantage can be combined to realize the real-time and fast temperature difference control. In the Simulink, the s-function of this control strategy is used to carry out a dynamic simulation experiment with temperature difference characteristics and verify the robustness and response to model mismatch. Compared to conventional temperature difference-flow PID cascade control and single neuron PID cascade control, this control strategy has better robustness and stronger adaptability. The results of real-time control on the THJSK-1 experiment platform indicate this control strategy is feasible.
文摘Using similar single-difference methodology(SSDM) to solve the deformation values of the monitoring points, there is unstability of the deformation information series, at sometimes.In order to overcome this shortcoming, Kalman filtering algorithm for this series is established,and its correctness and validity are verified with the test data obtained on the movable platform in plane. The results show that Kalman filtering can improve the correctness, reliability and stability of the deformation information series.
文摘This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency shift and path difference,the virtual path difference is calculated from the measured value of Doppler frequency shift by means of mean value correction.Then,under the assumption that the target is moving at a constant speed along a straight line,two coaxial virtual double base arrays are constructed by using the moving track of the moving target based on the method of fixed period time difference.On this basis,the moving distance of the moving target can be calculated by using the ratio relationship between the frequency difference and the radial distance between the two adjacent detection points in the middle of the array,and the linear solution of the two double base path difference positioning equations.At this point,the relative coordinate position of the moving target can be obtained by directly using the linear solution of the double base path difference positioning equation again.
文摘[Objective] The aim was to explore the reasons of false positives in Different Display Reverse Transcription(DDRT)analysis.[Method] Soybean varieties "Jilin 30" and "Tongnong 13" were used as materials to carry out analysis on false positives in DDRT analysis.[Result] An important origin of false positives appeared in DDRT analysis was the non-specific amplification caused by the combination of single primer and cDNA.The parallel PCR test of single primer should be set so as to verify whether the obtained fragments were the false positives or the PCR productions combined with single primer.[Conclusion] This study had provided basis for improving the success rate of DDRT experiment.
基金supported by the National Natural Science Foundation of China(61401389).
文摘The advancement of small satellites is promoting the development of distributed satellite systems,and for the latter,it is essential to coordinate the spatial and temporal relations between mutually visible satellites.By now,dual one-way ranging(DOWR)and two-way time transfer(TWTT)are generally integrated in the same software and hardware system to meet the limitations of small satellites in terms of size,weight and power(SWaP)consumption.However,studies show that pseudo-noise regenerative ranging(PNRR)performs better than DOWR if some advanced implementation technologies are employed.Besides,PNRR has no requirement on time synchronization.To apply PNRR to small satellites,and meanwhile,meet the demand for time difference measurement,we propose the round-way time difference measurement,which can be combined with PNRR to form a new integrated system without exceeding the limits of SWaP.The new integrated system can provide distributed small satellite systems with on-orbit high-accuracy and high-precision distance measurement and time difference measurement in real time.Experimental results show that the precision of ranging is about 1.94 cm,and that of time difference measurement is about 78.4 ps,at the signal to noise ratio of 80 dBHz.
文摘An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved. These potentials were clarified with some experimental extraction-data reported before on the M = Ag(I), Ca(II), Sr(II) and Ba(II) extraction with 18-crown-6 ether (18C6) and benzo-18C6 into 1,2-dichloroethane (DCE) and nitrobenzene (NB). Consequently, it was demonstrated that the? values from the extraction-experimentally obtained logKD,Pic ones are in agreement with or close to those calculated from charge balance equations in many cases, where the symbol, KD,Pic, denotes an individual distribution constant of Pic﹣ into the DCE or NB phase. Also, it was experimentally shown that extraction constants based on the overall extraction equilibria do not virtually contain the? terms in their functional expressions.
文摘不对称接地故障占所有线路故障的90%以上,接地距离保护在应对此类故障方面发挥了不可替代的作用。随着新能源高比例渗透,各种传统单端工频量保护性能显著下降已成为共识。基于故障分量线模和零模波速差的保护判据理论上仅需利用到故障初始行波到达时刻信息,是一种原理简单可靠的单端量快速保护判据,已经在直流电网中成功实践。但在尝试将这类保护应用于交流电网时发现,受波头前陡较缓而难以精确定位波到时刻、依赖高采样率等诸多不利因素影响,存在过大的模糊判别区,除了特长线路外,对绝大部分线路几乎没有应用可行性。波到时刻的精准辨识是一个复杂的非线性问题,利用人工智能的方法进行辨识是一条可行的解决思路,对此,该文提出一种新的单端暂态量主保护判据。首先,分析波达时刻与波形关系,并指出这种关系能够采用机器学习来映射;其次,引入高斯过程回归(Gaussian process regression,GPR),在对初始行波数据进行预处理得到样本集后,输入GPR预测模型进行训练;然后,依据模型评估指标得到最优训练模型以输出高可信性的线-零模波达时差,据此实现了基于行波模量传输时间差的保护判据;最后,在利用PSCAD仿真验证所提保护判据有效性和普适性的基础上,进一步利用现场实测数据对判据进行测试,验证其实用性。该文工作为新能源交流系统下单端暂态量保护的性能提升提供新的解决思路。