A new approach to gain-scheduling of H∞controllers is proposed for a cruise missile with variableswept wings( VSW) in bank-to-turn( BTT) mode. A nonlinear dynamic model is established and anticipant performance crite...A new approach to gain-scheduling of H∞controllers is proposed for a cruise missile with variableswept wings( VSW) in bank-to-turn( BTT) mode. A nonlinear dynamic model is established and anticipant performance criterions are given at first. For the selected operating points,feedback robust controllers of threechannels are designed independently to restrain cross-channel couple disturbances and aerodynamic perturbations. Then,the sweepback and Ma number are selected to schedule controller gains iteratively to ensure all closed-loop poles locating inside the desired region. The proposed method here attempts to extend the performance of initial design obtained for a single arbitrary point to the whole linearized domain while maintaining the expected stability over the entire range of sweepback and full flight envelope. Some time-domain analysis procedures based on the proposed method are carried out and assessed,while the performance of tracking and robustness to aerodynamic perturbations in different situations are contrasted by some nonlinear simulations. Finally,the numerical simulations demonstrate that the proposed autopilot design method has better tracking performance and is robust,effective and feasible.展开更多
Rare earth elements and yttrium(REY)in coal deposits are considered promising alternative sources for these resources owing to their increasing global demand.This paper reports the geochemical characteristics of REY i...Rare earth elements and yttrium(REY)in coal deposits are considered promising alternative sources for these resources owing to their increasing global demand.This paper reports the geochemical characteristics of REY in the Late Permian coals from an underground K1a seam section of the Zhongliangshan coalfield in Chongqing,southwestern China.The mineralogy,degree of enrichment,distribution patterns,modes of occurrence,and sediment origin of REY were investigated.Compared with the average of world coals,the concentration of REY in the K1a coals were normal,dominated by light REY(LREY),with less medium and heavy REY(MREY,HREY).The fractionation degree of the MREY and HREY are higher than that of LREY in most K1a coal samples,deduced from the mixed enrichment type of REY,mainly including M-H-type,and a few L-M type and H-type.In addition,the combination of anomalies of Ce,Eu,Gd,and Al_(2)O_(3)/TiO_(2) parameters,the terrigenous materials in the K1a coal were derived from the felsic-intermediate rocks at the top of the Emeishan basalt sequence,and the samples were affected by seawater intrusion during early peat accumulation.Although the minerals primarily consist of kaolinite,illite,pyrite,and small amounts of quartz,calcite and anatase,REY are correlated with ash yield,SiO2,and Al_(2)O_(3),revealing that the REY mainly occur in aluminosilicate minerals,especially kaolinite and illite.Meanwhile,REY positively relate to P_(2)O_(5) and Zr,which may exist in phosphate-containing minerals or zircon.Furthermore,most samples in the K1a coal or ash do not reach the cut-off grade for the beneficial recovery of REY.With the exception of central Guizhou,southwestern Chongqing,and the junction of western Guizhou and northeastern Yunnan,the REY content in coals from southwestern China are high,and its by-products are suitable as potential REY sources.展开更多
This paper proposes an artificial neural network to determine orientation using polarized skylight. This neural network has specific dilated convolution, which can extract light intensity information of different pola...This paper proposes an artificial neural network to determine orientation using polarized skylight. This neural network has specific dilated convolution, which can extract light intensity information of different polarization directions. Then, the degree of polarization (DOP) and angle of polarization (AOP) are directly extracted in the network. In addition, the exponential function encoding of orientation is designed as the network output, which can better reflect the insect’s encoding of polarization information and improve the accuracy of orientation determination. Finally, training and testing were conducted on a public polarized skylight navigation dataset, and the experimental results proved the stability and effectiveness of the network.展开更多
基金Sponsored by Armament Department Pre-Research Foundation of China(Grant No.9140A31010114JB25465)Natural Science Foundation of Jiangsu Province(Grant No.BK20140795)Chinese Aerospace CAST Innovation Foundation(Grant No.CAST2014-27)
文摘A new approach to gain-scheduling of H∞controllers is proposed for a cruise missile with variableswept wings( VSW) in bank-to-turn( BTT) mode. A nonlinear dynamic model is established and anticipant performance criterions are given at first. For the selected operating points,feedback robust controllers of threechannels are designed independently to restrain cross-channel couple disturbances and aerodynamic perturbations. Then,the sweepback and Ma number are selected to schedule controller gains iteratively to ensure all closed-loop poles locating inside the desired region. The proposed method here attempts to extend the performance of initial design obtained for a single arbitrary point to the whole linearized domain while maintaining the expected stability over the entire range of sweepback and full flight envelope. Some time-domain analysis procedures based on the proposed method are carried out and assessed,while the performance of tracking and robustness to aerodynamic perturbations in different situations are contrasted by some nonlinear simulations. Finally,the numerical simulations demonstrate that the proposed autopilot design method has better tracking performance and is robust,effective and feasible.
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.U1903207,42172191,41972176,and 42002184)Natural Science Foundation of Hebei(No.D2021402013)+1 种基金Fundamental research Funds of China University of Mining and Technology(No.2020CXNL11)Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Rare earth elements and yttrium(REY)in coal deposits are considered promising alternative sources for these resources owing to their increasing global demand.This paper reports the geochemical characteristics of REY in the Late Permian coals from an underground K1a seam section of the Zhongliangshan coalfield in Chongqing,southwestern China.The mineralogy,degree of enrichment,distribution patterns,modes of occurrence,and sediment origin of REY were investigated.Compared with the average of world coals,the concentration of REY in the K1a coals were normal,dominated by light REY(LREY),with less medium and heavy REY(MREY,HREY).The fractionation degree of the MREY and HREY are higher than that of LREY in most K1a coal samples,deduced from the mixed enrichment type of REY,mainly including M-H-type,and a few L-M type and H-type.In addition,the combination of anomalies of Ce,Eu,Gd,and Al_(2)O_(3)/TiO_(2) parameters,the terrigenous materials in the K1a coal were derived from the felsic-intermediate rocks at the top of the Emeishan basalt sequence,and the samples were affected by seawater intrusion during early peat accumulation.Although the minerals primarily consist of kaolinite,illite,pyrite,and small amounts of quartz,calcite and anatase,REY are correlated with ash yield,SiO2,and Al_(2)O_(3),revealing that the REY mainly occur in aluminosilicate minerals,especially kaolinite and illite.Meanwhile,REY positively relate to P_(2)O_(5) and Zr,which may exist in phosphate-containing minerals or zircon.Furthermore,most samples in the K1a coal or ash do not reach the cut-off grade for the beneficial recovery of REY.With the exception of central Guizhou,southwestern Chongqing,and the junction of western Guizhou and northeastern Yunnan,the REY content in coals from southwestern China are high,and its by-products are suitable as potential REY sources.
基金Funding was provided by the National Key Research and Development Program of China(Grant No.2021ZD0200300)National Natural Science Foundation of China(NSFC)(U2031138).
文摘This paper proposes an artificial neural network to determine orientation using polarized skylight. This neural network has specific dilated convolution, which can extract light intensity information of different polarization directions. Then, the degree of polarization (DOP) and angle of polarization (AOP) are directly extracted in the network. In addition, the exponential function encoding of orientation is designed as the network output, which can better reflect the insect’s encoding of polarization information and improve the accuracy of orientation determination. Finally, training and testing were conducted on a public polarized skylight navigation dataset, and the experimental results proved the stability and effectiveness of the network.
