The problem of inter symbol interference( ISI) in wireless communication systems caused by multipath propagation when using high order modulation like M-Q AMis solved. Since the wireless receiver doesn't require a ...The problem of inter symbol interference( ISI) in wireless communication systems caused by multipath propagation when using high order modulation like M-Q AMis solved. Since the wireless receiver doesn't require a training sequence,a blind equalization channel is implemented in the receiver to increase the throughput of the system. To improve the performances of both the blind equalizer and the system,a joint receiving mechanismincluding variable step size( VSS) modified constant modulus algorithms( MC-MA) and modified decision directed modulus algorithms( MD DMA) is proposed to ameliorate the convergence speed and mean square error( MSE) performance and combat the phase error when using high order QAM modulation. The VSS scheme is based on the selection of step size according to the distance between the output of the equalizer and the desired output in the constellation plane. Analysis and simulations showthat the performance of the proposed VSS-MCMA-MD DMA mechanismis better than that of algorithms with a fixed step size. In addition,the MCMA-MDDMA with VSS can performthe phase recovery by itself.展开更多
A novel inorganic-organic hybrid supramolecular compound,[(3-nitroanilinium^+)(18-crown-6)][IO4](CH3OH)(1),was discovered as phase-transition materials displaying dielectric anomalous behaviors.The yellow blo...A novel inorganic-organic hybrid supramolecular compound,[(3-nitroanilinium^+)(18-crown-6)][IO4](CH3OH)(1),was discovered as phase-transition materials displaying dielectric anomalous behaviors.The yellow block crystal formed by N-H…O hydrogen bonding that made contact through the cavity of 18-crown-6 was characterized by single-crystal X-ray diffraction,elemental analysis,infrared analysis,thermogravimetric analysis,differential scanning calorimetry,and potential-energy calculations.Differential scanning calorimetry measurements indicate that the compound experiences a reversible phase transition at around 220 K.Temperature-dependent dielectric measurements further confirm the phase transitions.Potential-energy calculations demonstrate that the phase transition occurs due to the molecular order-disorder rotation of CH3OH,whereas the space grouping of the crystal remains unchanged.展开更多
Ideal proportional navigation (IPN) is a natural choice for exoatmospheric interception for its mighty capture capability and ease of implementation. The closed-form solution of two- dimensional ideal proportional n...Ideal proportional navigation (IPN) is a natural choice for exoatmospheric interception for its mighty capture capability and ease of implementation. The closed-form solution of two- dimensional ideal proportional navigation was conducted in previous public literature, whereas the practical interception happens in the three-dimensional space. A novel set of relative dynamic equations is adopted in this paper, which is with the advantage of decoupling relative motion in the instantaneous rotation plane of the line of sight from the rotation of this plane. The dimension-reduced IPN is constructed in this instantaneous plane, which functions as a three-dimensional guidance law. The trajectory features of dimension-reduced IPN are explored, and the capture regions of dimension-reduced IPN with limited acceleration against nonmaneuvering and maneuvering targets are analyzed by using phase plane method. It is proved that the capture capability of IPN is much stronger than true proportional navigation (TPN), no matter the target maneuvers or not. Finally, simulation results indicate that IPN is more effective than TPN in exoatmospheric interception scenarios.展开更多
Array gain would be well exploited to improve power coverage if some powerful multipath components from different radio links can coherently combine at the receiver (Rx). Thus, in this paper, an algorithm is propose...Array gain would be well exploited to improve power coverage if some powerful multipath components from different radio links can coherently combine at the receiver (Rx). Thus, in this paper, an algorithm is proposed for transmission in simulcast system, where partial channel state information (CSI) is needed. Based on measured multipath channel, performance of the proposed algorithm is evaluated. According to simulation results, the proposed algorithm outperforms the direction summation (DS) scheme and multipath antenna diversity (MAD) algorithm, with 2~4 dB advantage over the latters. Especially in line of sight (LOS) scenario, the advantage is more obvious. Besides, the proposed algorithm brings more gain with increasing number of transmit antennas without additional power. Finally, robustness of the proposed algorithm is examined with imperfect CSI.展开更多
The feasibility of attaining a short-pulse-duration heavy ion beam with a nanosecond pulse length is studied in the main ring of the Heavy Ion Research Facility in Lanzhou (HIRFL). Such a heavy ion beam can be produ...The feasibility of attaining a short-pulse-duration heavy ion beam with a nanosecond pulse length is studied in the main ring of the Heavy Ion Research Facility in Lanzhou (HIRFL). Such a heavy ion beam can be produced by non-adiabatic compression, and it is implemented by fast rotation in the longitudinal phase space. In this paper, the possible beam parameters during longitudinal bunch compression are studied by using the envelope model. The result shows that a shortest heavy ion bunch 23Su2S+ of 29 ns with energy of 200 MeV/u can be obtained, which can satisfy high energy density physics research.展开更多
基金Supported by the National Natural Science Foundation of China(6100201461101129+1 种基金6122700161072050)
文摘The problem of inter symbol interference( ISI) in wireless communication systems caused by multipath propagation when using high order modulation like M-Q AMis solved. Since the wireless receiver doesn't require a training sequence,a blind equalization channel is implemented in the receiver to increase the throughput of the system. To improve the performances of both the blind equalizer and the system,a joint receiving mechanismincluding variable step size( VSS) modified constant modulus algorithms( MC-MA) and modified decision directed modulus algorithms( MD DMA) is proposed to ameliorate the convergence speed and mean square error( MSE) performance and combat the phase error when using high order QAM modulation. The VSS scheme is based on the selection of step size according to the distance between the output of the equalizer and the desired output in the constellation plane. Analysis and simulations showthat the performance of the proposed VSS-MCMA-MD DMA mechanismis better than that of algorithms with a fixed step size. In addition,the MCMA-MDDMA with VSS can performthe phase recovery by itself.
基金supported by National Natural Science Foundation of China (No. 21561030)Prophase-sustentation Fund of Xinjiang Agricultural University (Nos. XJAU201410 and XJAU201511)
文摘A novel inorganic-organic hybrid supramolecular compound,[(3-nitroanilinium^+)(18-crown-6)][IO4](CH3OH)(1),was discovered as phase-transition materials displaying dielectric anomalous behaviors.The yellow block crystal formed by N-H…O hydrogen bonding that made contact through the cavity of 18-crown-6 was characterized by single-crystal X-ray diffraction,elemental analysis,infrared analysis,thermogravimetric analysis,differential scanning calorimetry,and potential-energy calculations.Differential scanning calorimetry measurements indicate that the compound experiences a reversible phase transition at around 220 K.Temperature-dependent dielectric measurements further confirm the phase transitions.Potential-energy calculations demonstrate that the phase transition occurs due to the molecular order-disorder rotation of CH3OH,whereas the space grouping of the crystal remains unchanged.
基金co-supported by the National Science Foundation of China(No.11222215)the National Basic Research Program of China(No.2013CB733100)
文摘Ideal proportional navigation (IPN) is a natural choice for exoatmospheric interception for its mighty capture capability and ease of implementation. The closed-form solution of two- dimensional ideal proportional navigation was conducted in previous public literature, whereas the practical interception happens in the three-dimensional space. A novel set of relative dynamic equations is adopted in this paper, which is with the advantage of decoupling relative motion in the instantaneous rotation plane of the line of sight from the rotation of this plane. The dimension-reduced IPN is constructed in this instantaneous plane, which functions as a three-dimensional guidance law. The trajectory features of dimension-reduced IPN are explored, and the capture regions of dimension-reduced IPN with limited acceleration against nonmaneuvering and maneuvering targets are analyzed by using phase plane method. It is proved that the capture capability of IPN is much stronger than true proportional navigation (TPN), no matter the target maneuvers or not. Finally, simulation results indicate that IPN is more effective than TPN in exoatmospheric interception scenarios.
基金supported by the National Natural Science Foundation of China(61171105)China Information Technology Designing & Consulting Institute Ltd(CITC)-School of Information and Communication Engineering(SICE)in BUPT Graduate Innovation Fund for 2011
文摘Array gain would be well exploited to improve power coverage if some powerful multipath components from different radio links can coherently combine at the receiver (Rx). Thus, in this paper, an algorithm is proposed for transmission in simulcast system, where partial channel state information (CSI) is needed. Based on measured multipath channel, performance of the proposed algorithm is evaluated. According to simulation results, the proposed algorithm outperforms the direction summation (DS) scheme and multipath antenna diversity (MAD) algorithm, with 2~4 dB advantage over the latters. Especially in line of sight (LOS) scenario, the advantage is more obvious. Besides, the proposed algorithm brings more gain with increasing number of transmit antennas without additional power. Finally, robustness of the proposed algorithm is examined with imperfect CSI.
基金Supported by National Natural Science Foundation of China (10905082)
文摘The feasibility of attaining a short-pulse-duration heavy ion beam with a nanosecond pulse length is studied in the main ring of the Heavy Ion Research Facility in Lanzhou (HIRFL). Such a heavy ion beam can be produced by non-adiabatic compression, and it is implemented by fast rotation in the longitudinal phase space. In this paper, the possible beam parameters during longitudinal bunch compression are studied by using the envelope model. The result shows that a shortest heavy ion bunch 23Su2S+ of 29 ns with energy of 200 MeV/u can be obtained, which can satisfy high energy density physics research.