The DLBSW（ dual laser-beam bilateral synchronous welding） technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanica...The DLBSW（ dual laser-beam bilateral synchronous welding） technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanical behavior of this process, it is necessary to establish a reasonable heat source model. Two different surface-body combination heat source models are adopted in this paper. Both models use the Gaussian surface heat source model and one is combined with the cone body heat source model and the other is combined with Gaussian rotator body heat source model. The simulation results of these two different models are investigated. And the temperature field results of DLBSW process for T-joint with two different heat sources are discussed. It is indicated that the combination heat source model is effective to simulate the DLBSW process and the current study is useful for more profound research in this field.展开更多
Free electron lasers provide high-power and ultrashort pulses with extreme brightness. In order to improve a facility's capabilities and explore the possibility of performing high-resolution time-resolved experime...Free electron lasers provide high-power and ultrashort pulses with extreme brightness. In order to improve a facility's capabilities and explore the possibility of performing high-resolution time-resolved experiments, a beam arrival time resolution under 100 fs is required. In this article, a novel beam arrival time monitor(BAM)equipped with two cavities has been designed and a beam flight time measurement scheme based on the BAM prototype has been proposed to estimate phase jitter in the signal measurement system. The two BAM cavities work at different frequencies and the frequency difference is designed to be 35 MHz. Therefore, a self-mixing intermediate frequency signal can be generated using the two cavities. The measured beam flight time shows a temporal deviation of 37 fs(rms).展开更多
As a kind of special acoustic field, the helical wavefront of an acoustic vortex（AV） beam is demonstrated to have a pressure zero with phase singularity at the center in the transverse plane. The orbital angular mom...As a kind of special acoustic field, the helical wavefront of an acoustic vortex（AV） beam is demonstrated to have a pressure zero with phase singularity at the center in the transverse plane. The orbital angular momentum of AVs can be applied to the field of particle manipulation, which attracts more and more attention in acoustic researches. In this paper,by using the simplified circular array of point sources, dual coaxial AV beams are excited by the even-and odd-numbered sources with the topological charges of l_E and l_O based on the phase-coded approach, and the composite acoustic field with an on-axis center-AV and multiple off-axis sub-AVs can be generated by the superimposition of the AV beams for｜l_E｜ ≠ ｜l_O｜. The generation of edge phase dislocation is theoretically derived and numerically analyzed for l_E=-l_O. The numbers and the topological charges as well as the locations of the center-AV and sub-AVs are demonstrated, which are proved to be determined by the topological charges of the coaxial AV beams. The proposed approach breaks through the limit of only one on-axis AV with a single topological charge along the beam axis, and also provides the feasibility of off-axis particle trapping with multiple AVs in object manipulation.展开更多
In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. Th...In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. The XRD and TEM results show that the deposited films have an amorphous structure. In the XPS result, we find N 1s spectra consist of one symmetric single peak at 397.8 eV, indicating that the nitrogen atoms are mainly bonded to silicon. It is in agreement to the result of FTIR. In SiOxNy films, an intense single PL peak at 590 nm is observed. Furthermore, with the increase of the N content in the SiOxNy films, the intensity of the PL peak at 590 nm increases a lot. The PL peak of 590 nm is suggested to originate from N-related defects.展开更多
Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the i...Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the increase in substrate temperature (TS). The magnetic properties of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).展开更多
A long-/long-wave dual-color detector with N-M-π-B-π-M-N structure was developed based on a type-Ⅱ InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The devic...A long-/long-wave dual-color detector with N-M-π-B-π-M-N structure was developed based on a type-Ⅱ InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The device could be operated as a single detector for sequential detection and showed high quantum efficiencies. The peak quantum efficiencies of long-wavelength infrared band-1(blue channel) and long-wavelength infrared band-2(red channel) were 44% at 6.3 μm under 20 mV and 57% at 9.1 μm under-60 mV, respectively. The optical performance for each channel was achieved using a 2 μm thickness absorber. Due to the high QE, the specific detectivities of the blue and red channels reached5.0×10^(11) cm·Hz^(1/2)/W at 6.8 μm and 3.1×10^(11) cm·Hz1^(1/2)/W at 9.1 μm, respectively, at 77 K.展开更多
Bi-function Compact graphene lens antenna in terahertz (THz) band has been investigated. The array function is switched between two status, reflectarray and/or transmitarray. The tunability of graphene conductivity in...Bi-function Compact graphene lens antenna in terahertz (THz) band has been investigated. The array function is switched between two status, reflectarray and/or transmitarray. The tunability of graphene conductivity introduces the bi-function characteristics of a single array structure in the THz band. The design depends on changing the graphene DC biasing voltage to transform the transmitting antenna to reflecting antenna. The compact structure of the antenna array saves the cost and the allocation area for the terahertz communication applications. A 13 × 13 reflectarray/ transmitarray antenna covering an area of 364 × 364 μm<sup>2</sup> is proposed. A dual-beams reflectarray/transmitarray antenna is achieved by rearranging the cell elements of the array successively. Finally, a single structure is used to work as reflectarray and transmitarray antenna at the same time by rearranging the applied voltages between the different pieces of the graphene sheet using chess board arrangement. The phases of the successive unit-cells are kept the same of their locations in the original full array. The radiation characteristics of the array are investigated using the CST Microwave Studio for the bi-function operation.展开更多
基金The research is sponsored by the Shanghai STCSM Project of the Postdoctoral Science Research Assistant Plan （10R21421200）, the National Natural Science Foundation of China （50904038） and the China Postdoctoral Science Foundation （20100470064）.
文摘The DLBSW（ dual laser-beam bilateral synchronous welding） technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanical behavior of this process, it is necessary to establish a reasonable heat source model. Two different surface-body combination heat source models are adopted in this paper. Both models use the Gaussian surface heat source model and one is combined with the cone body heat source model and the other is combined with Gaussian rotator body heat source model. The simulation results of these two different models are investigated. And the temperature field results of DLBSW process for T-joint with two different heat sources are discussed. It is indicated that the combination heat source model is effective to simulate the DLBSW process and the current study is useful for more profound research in this field.
基金supported by the National Natural Science Foundation of China(No.11575282)
文摘Free electron lasers provide high-power and ultrashort pulses with extreme brightness. In order to improve a facility's capabilities and explore the possibility of performing high-resolution time-resolved experiments, a beam arrival time resolution under 100 fs is required. In this article, a novel beam arrival time monitor(BAM)equipped with two cavities has been designed and a beam flight time measurement scheme based on the BAM prototype has been proposed to estimate phase jitter in the signal measurement system. The two BAM cavities work at different frequencies and the frequency difference is designed to be 35 MHz. Therefore, a self-mixing intermediate frequency signal can be generated using the two cavities. The measured beam flight time shows a temporal deviation of 37 fs(rms).
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474166 and 11604156)the Science and Technology Cooperation Projects of People’s Republic of China–Romania(Grant No.42-23)+2 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161013)the Postdoctoral Science Foundation of China(Grant No.2016M591874)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘As a kind of special acoustic field, the helical wavefront of an acoustic vortex（AV） beam is demonstrated to have a pressure zero with phase singularity at the center in the transverse plane. The orbital angular momentum of AVs can be applied to the field of particle manipulation, which attracts more and more attention in acoustic researches. In this paper,by using the simplified circular array of point sources, dual coaxial AV beams are excited by the even-and odd-numbered sources with the topological charges of l_E and l_O based on the phase-coded approach, and the composite acoustic field with an on-axis center-AV and multiple off-axis sub-AVs can be generated by the superimposition of the AV beams for｜l_E｜ ≠ ｜l_O｜. The generation of edge phase dislocation is theoretically derived and numerically analyzed for l_E=-l_O. The numbers and the topological charges as well as the locations of the center-AV and sub-AVs are demonstrated, which are proved to be determined by the topological charges of the coaxial AV beams. The proposed approach breaks through the limit of only one on-axis AV with a single topological charge along the beam axis, and also provides the feasibility of off-axis particle trapping with multiple AVs in object manipulation.
基金The project supported by the Nature Science Foundation of University of Jiangsu Province(No. 03KJB140116 )
文摘In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. The XRD and TEM results show that the deposited films have an amorphous structure. In the XPS result, we find N 1s spectra consist of one symmetric single peak at 397.8 eV, indicating that the nitrogen atoms are mainly bonded to silicon. It is in agreement to the result of FTIR. In SiOxNy films, an intense single PL peak at 590 nm is observed. Furthermore, with the increase of the N content in the SiOxNy films, the intensity of the PL peak at 590 nm increases a lot. The PL peak of 590 nm is suggested to originate from N-related defects.
基金Jiangsu Province key laboratory of thin film with Grant No. K2021.
文摘Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the increase in substrate temperature (TS). The magnetic properties of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).
基金supported by the National Key Technology R&D Program of China(Grant Nos.2018YFA0209104 and 2016YFB0402403)
文摘A long-/long-wave dual-color detector with N-M-π-B-π-M-N structure was developed based on a type-Ⅱ InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The device could be operated as a single detector for sequential detection and showed high quantum efficiencies. The peak quantum efficiencies of long-wavelength infrared band-1(blue channel) and long-wavelength infrared band-2(red channel) were 44% at 6.3 μm under 20 mV and 57% at 9.1 μm under-60 mV, respectively. The optical performance for each channel was achieved using a 2 μm thickness absorber. Due to the high QE, the specific detectivities of the blue and red channels reached5.0×10^(11) cm·Hz^(1/2)/W at 6.8 μm and 3.1×10^(11) cm·Hz1^(1/2)/W at 9.1 μm, respectively, at 77 K.
文摘Bi-function Compact graphene lens antenna in terahertz (THz) band has been investigated. The array function is switched between two status, reflectarray and/or transmitarray. The tunability of graphene conductivity introduces the bi-function characteristics of a single array structure in the THz band. The design depends on changing the graphene DC biasing voltage to transform the transmitting antenna to reflecting antenna. The compact structure of the antenna array saves the cost and the allocation area for the terahertz communication applications. A 13 × 13 reflectarray/ transmitarray antenna covering an area of 364 × 364 μm<sup>2</sup> is proposed. A dual-beams reflectarray/transmitarray antenna is achieved by rearranging the cell elements of the array successively. Finally, a single structure is used to work as reflectarray and transmitarray antenna at the same time by rearranging the applied voltages between the different pieces of the graphene sheet using chess board arrangement. The phases of the successive unit-cells are kept the same of their locations in the original full array. The radiation characteristics of the array are investigated using the CST Microwave Studio for the bi-function operation.
