The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on20...The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.展开更多
The reduction behavior of iron ore pellets containing carbon under non-isothermal condition in the temperature range from 573 to 1373 K was investigated in a laboratory scale setup. The test results show that carbon c...The reduction behavior of iron ore pellets containing carbon under non-isothermal condition in the temperature range from 573 to 1373 K was investigated in a laboratory scale setup. The test results show that carbon content has no obvious effect on reduction degree of composite pellets (C/O mole ratio=1.0) by CO in the temperature range from 573 to 1373 K under linear temperature-rising program; reduction degree of iron ore pellets containing carbon is large in 90%CO-10%CO2 mixture than that of in 100%CO atmosphere or in 80%CO-20%CO2 mixture; the s type temperature-rising program has a better effect than that of linear one in increasing the reduction degree; and reduction degree of slower linear temperature-rising program is greater than that of faster one, but the final reduction degrees, i.e., those at the highest temperature are about the same for various CO partial pressures or temperature-rising programs. The kinetic analysis also shows that the reduction of iron ore-carbon composite pellets by CO or CO-CO2 mixture under non-isothermal condition should be controlled by surface reaction, and the apparent reduction activation energy changes with the reduction progress under various test conditions.展开更多
Knot theory provides a powerful tool for understanding topological matters in biology,chemistry,and physics.Here knot theory is introduced to describe topological phases in a quantum spin system.Exactly solvable model...Knot theory provides a powerful tool for understanding topological matters in biology,chemistry,and physics.Here knot theory is introduced to describe topological phases in a quantum spin system.Exactly solvable models with long-range interactions are investigated,and Majorana modes of the quantum spin system are mapped into different knots and links.The topological properties of ground states of the spin system are visualized and characterized using crossing and linking numbers,which capture the geometric topologies of knots and links.The interactivity of energy bands is highlighted.In gapped phases,eigenstate curves are tangled and braided around each other,forming links.In gapless phases,the tangled eigenstate curves may form knots.Our findings provide an alternative understanding of phases in the quantum spin system,and provide insights into one-dimension topological phases of matter.展开更多
The mechanical behavior of seven different carbon nanotube(CNT)X-junctions with a varying number of bonds was investigated through molecular dynamics simulations.The X-junctions are composed of two(6,0)single-walled c...The mechanical behavior of seven different carbon nanotube(CNT)X-junctions with a varying number of bonds was investigated through molecular dynamics simulations.The X-junctions are composed of two(6,0)single-walled carbon nanotubes(SWNTs)created via vibration-assisted heat welding.The junctions,containing anywhere between one and seven bonds,are subject to uniaxial tensile,shear and torsional strain,and then the stiffness values are determined for each case.When subjected to tensile and shear strain,both the arrangement and orientation of bonds are found to affect the stiffness of junctions more substantially than the number of bonds,bond length or bond order.Surprisingly,anisotropic shear behavior is observed in the X-junctions,which can be attributed to the junction’s bond orientation.Also,the stiffness of X-junctions tested under an applied torque(torsion)differs from the stiffness under tensile and shear strain,however,in that it is more substantially affected by the number of bonds present in the junction than by any other property.展开更多
基金supported by the Einstein Probe project,a mission in the Strategic Priority Program on Space Science of CAS(grant Nos.XDA15310000,XDA15052100)in part been supported by the European Union’s Horizon 2020 Program under the AHEAD2020 project(grant No.871158).
文摘The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.
文摘The reduction behavior of iron ore pellets containing carbon under non-isothermal condition in the temperature range from 573 to 1373 K was investigated in a laboratory scale setup. The test results show that carbon content has no obvious effect on reduction degree of composite pellets (C/O mole ratio=1.0) by CO in the temperature range from 573 to 1373 K under linear temperature-rising program; reduction degree of iron ore pellets containing carbon is large in 90%CO-10%CO2 mixture than that of in 100%CO atmosphere or in 80%CO-20%CO2 mixture; the s type temperature-rising program has a better effect than that of linear one in increasing the reduction degree; and reduction degree of slower linear temperature-rising program is greater than that of faster one, but the final reduction degrees, i.e., those at the highest temperature are about the same for various CO partial pressures or temperature-rising programs. The kinetic analysis also shows that the reduction of iron ore-carbon composite pellets by CO or CO-CO2 mixture under non-isothermal condition should be controlled by surface reaction, and the apparent reduction activation energy changes with the reduction progress under various test conditions.
基金Supported by the National Natural Science Foundation of China(Grants Nos.11874225,11975128,and 11605094)。
文摘Knot theory provides a powerful tool for understanding topological matters in biology,chemistry,and physics.Here knot theory is introduced to describe topological phases in a quantum spin system.Exactly solvable models with long-range interactions are investigated,and Majorana modes of the quantum spin system are mapped into different knots and links.The topological properties of ground states of the spin system are visualized and characterized using crossing and linking numbers,which capture the geometric topologies of knots and links.The interactivity of energy bands is highlighted.In gapped phases,eigenstate curves are tangled and braided around each other,forming links.In gapless phases,the tangled eigenstate curves may form knots.Our findings provide an alternative understanding of phases in the quantum spin system,and provide insights into one-dimension topological phases of matter.
基金supported by NSF REU through grants(CMMI-0928094 and BRIGE-EEC-0926885)the Swanson School of Engineering at the University of Pittsburgh.
文摘The mechanical behavior of seven different carbon nanotube(CNT)X-junctions with a varying number of bonds was investigated through molecular dynamics simulations.The X-junctions are composed of two(6,0)single-walled carbon nanotubes(SWNTs)created via vibration-assisted heat welding.The junctions,containing anywhere between one and seven bonds,are subject to uniaxial tensile,shear and torsional strain,and then the stiffness values are determined for each case.When subjected to tensile and shear strain,both the arrangement and orientation of bonds are found to affect the stiffness of junctions more substantially than the number of bonds,bond length or bond order.Surprisingly,anisotropic shear behavior is observed in the X-junctions,which can be attributed to the junction’s bond orientation.Also,the stiffness of X-junctions tested under an applied torque(torsion)differs from the stiffness under tensile and shear strain,however,in that it is more substantially affected by the number of bonds present in the junction than by any other property.
