We investigate the single-pulse emission variations of two pulsars,PSRs J0211+4235 and J0553+4111,observed with the Five-hundred-meter Aperture Spherical radio Telescope at the 1.25 GHz central frequency.The observati...We investigate the single-pulse emission variations of two pulsars,PSRs J0211+4235 and J0553+4111,observed with the Five-hundred-meter Aperture Spherical radio Telescope at the 1.25 GHz central frequency.The observation sessions span from 2020 December to 2021 July,with 21 and 22 observations for them respectively.The integrated pulse profile of PSR J0211+4235 shows that there is a weak pulse component following the main component,and PSR J0553+4111 displays a bimodal profile with a bridge component in the middle.PSR J0211+4235 presents significant nulling phenomenon with nulling duration lasting from 2 to 115 pulses and burst duration lasting from 2 to 113 pulses.The NF of each observation is determined to be 45%-55%.No emission greater than threeσis found in the mean integrated profile of all nulling pulses.In most cases,the pulse energy changes abruptly during the transition from null to burst,while in the transition from burst to null there are two trends:abrupt and gradual.We find that the nulling phenomenon of PSR J0211+4235 is periodic by the Fourier transform of the null and burst state.In addition,the single-pulse modulation characteristics of these two pulsars are investigated,and the distributions of modulation index,LRFS and 2DFS are analyzed with PSRSALSA.The left peak of PSR J0553+4111 has intensity modulation.Finally,the polarization properties of these two pulsars are obtained through polarization calibration,and their characteristics are analyzed.The possible physical mechanisms of these phenomena are discussed.展开更多
For the simultaneous wireless information and power transfer(SWIPT), the full-duplex MIMO system can achieve simultaneous transmission of information and energy more efficiently than the half-duplex. Based on the mean...For the simultaneous wireless information and power transfer(SWIPT), the full-duplex MIMO system can achieve simultaneous transmission of information and energy more efficiently than the half-duplex. Based on the mean-square-error(MSE) criterion, the optimization problem of joint transceiver design with transmitting power constraint and energy harvesting constraint is formulated. Next, by semidefinite relaxation(SDR) and randomization method, the SDRbased scheme is proposed. In order to reduce the complexity, the closed-form scheme is presented with some simplified measures. Robust beamforming is then studied considering the practical condition. The simulation results such as MSE versus signal-noise-ratio(SNR), MSE versus the iteration number, well prove the performance of the proposed schemes for the system model.展开更多
Deformation of coals under tectonic movements could cause reduction of mechanical strength and enhancement of gas adsorption,which might result in coal and gas outburst,and cause safety and environmental issues.In thi...Deformation of coals under tectonic movements could cause reduction of mechanical strength and enhancement of gas adsorption,which might result in coal and gas outburst,and cause safety and environmental issues.In this study,geophysical characteristics of coals with various structures were investigated with a special emphasis on characterization of pore size distribution,rock mechanical strength,acoustic emission,resistivity and acoustic velocity of anthracites with three types of structures in the Qinshui Basin,north China.The studied No.3 coal seam developed three types of structures,namely undeformed coal,cataclastic coal,and granular coal.Petrographic observations under scanning electron microscope and pore size distribution using N2 and CO_(2) adsorption of anthracites of three types show that the undeformed coal consists of primary micropores,and cataclastic coal is mainly composed of mesopores and well-connected fractures.In comparison,granular coal has the least mesopores.Rock mechanical strength,acoustic emission,resistivity and acoustic velocity of coals with three structure types were investigated under uniaxial and triaxial compression.With increasing degree of deformation of anthracites,compression strength,Young’s modulus,density,acoustic emission counting and acoustic velocity decreases,while resistivity increases.We suggest that the evolution of pore size distribution of anthracites with increasing degree of deformation contributed to variations of geophysical characteristics of coals with different structures to some extent.展开更多
基金supported by National Key Research and Development Program of China(2022YFC2205203)the Major Science and Technology Program of Xinjiang Uygur Autonomous Region(No.2022A03013-1)+3 种基金the National Natural Science Foundation of China(NSFC,Grant Nos.U1838109,12041304)supported by the 2021 project Xinjiang Uygur autonomous region of China for Tianshan elitesthe Youth Innovation Promotion Association of CAS under No.2023069support from the Natural Science Foundation of Shanghai(Grant No.20ZR1467600)。
文摘We investigate the single-pulse emission variations of two pulsars,PSRs J0211+4235 and J0553+4111,observed with the Five-hundred-meter Aperture Spherical radio Telescope at the 1.25 GHz central frequency.The observation sessions span from 2020 December to 2021 July,with 21 and 22 observations for them respectively.The integrated pulse profile of PSR J0211+4235 shows that there is a weak pulse component following the main component,and PSR J0553+4111 displays a bimodal profile with a bridge component in the middle.PSR J0211+4235 presents significant nulling phenomenon with nulling duration lasting from 2 to 115 pulses and burst duration lasting from 2 to 113 pulses.The NF of each observation is determined to be 45%-55%.No emission greater than threeσis found in the mean integrated profile of all nulling pulses.In most cases,the pulse energy changes abruptly during the transition from null to burst,while in the transition from burst to null there are two trends:abrupt and gradual.We find that the nulling phenomenon of PSR J0211+4235 is periodic by the Fourier transform of the null and burst state.In addition,the single-pulse modulation characteristics of these two pulsars are investigated,and the distributions of modulation index,LRFS and 2DFS are analyzed with PSRSALSA.The left peak of PSR J0553+4111 has intensity modulation.Finally,the polarization properties of these two pulsars are obtained through polarization calibration,and their characteristics are analyzed.The possible physical mechanisms of these phenomena are discussed.
基金supported by the National Great Science Specif ic Project (Grants No. 2014ZX03002002-004)National Natural Science Foundation of China (Grants No. NSFC-61471067)
文摘For the simultaneous wireless information and power transfer(SWIPT), the full-duplex MIMO system can achieve simultaneous transmission of information and energy more efficiently than the half-duplex. Based on the mean-square-error(MSE) criterion, the optimization problem of joint transceiver design with transmitting power constraint and energy harvesting constraint is formulated. Next, by semidefinite relaxation(SDR) and randomization method, the SDRbased scheme is proposed. In order to reduce the complexity, the closed-form scheme is presented with some simplified measures. Robust beamforming is then studied considering the practical condition. The simulation results such as MSE versus signal-noise-ratio(SNR), MSE versus the iteration number, well prove the performance of the proposed schemes for the system model.
基金supported by the National Natural Science Foundation of China(Grant No.42102194).
文摘Deformation of coals under tectonic movements could cause reduction of mechanical strength and enhancement of gas adsorption,which might result in coal and gas outburst,and cause safety and environmental issues.In this study,geophysical characteristics of coals with various structures were investigated with a special emphasis on characterization of pore size distribution,rock mechanical strength,acoustic emission,resistivity and acoustic velocity of anthracites with three types of structures in the Qinshui Basin,north China.The studied No.3 coal seam developed three types of structures,namely undeformed coal,cataclastic coal,and granular coal.Petrographic observations under scanning electron microscope and pore size distribution using N2 and CO_(2) adsorption of anthracites of three types show that the undeformed coal consists of primary micropores,and cataclastic coal is mainly composed of mesopores and well-connected fractures.In comparison,granular coal has the least mesopores.Rock mechanical strength,acoustic emission,resistivity and acoustic velocity of coals with three structure types were investigated under uniaxial and triaxial compression.With increasing degree of deformation of anthracites,compression strength,Young’s modulus,density,acoustic emission counting and acoustic velocity decreases,while resistivity increases.We suggest that the evolution of pore size distribution of anthracites with increasing degree of deformation contributed to variations of geophysical characteristics of coals with different structures to some extent.
