Electromagnetic interference(EMI)shielding materials with superior shielding efficiency and low-reflection properties hold promising potential for utilization across electronic components,precision instruments,and fif...Electromagnetic interference(EMI)shielding materials with superior shielding efficiency and low-reflection properties hold promising potential for utilization across electronic components,precision instruments,and fifth-generation communication equipment.In this study,multistage microcellular waterborne polyurethane(WPU)composites were constructed via gradient induction,layer-by-layer casting,and supercritical carbon dioxide foaming.The gradient-structured WPU/ironcobalt loaded reduced graphene oxide(FeCo@rGO)foam serves as an impedance-matched absorption layer,while the highly conductive WPU/silver loaded glass microspheres(Ag@GM)layer is employed as a reflection layer.Thanks to the incorporation of an asymmetric structure,as well as the introduction of gradient and porous configurations,the composite foam demonstrates excellent conductivity,outstanding EMI SE(74.9 dB),and minimal reflection characteristics(35.28%)in 8.2-12.4 GHz,implying that more than 99.99999%of electromagnetic(EM)waves were blocked and only 35.28%were reflected to the external environment.Interestingly,the reflectivity of the composite foam is reduced to 0.41%at 10.88 GHz due to the resonance for incident and reflected EM waves.Beyond that,the composite foam is characterized by low density(0.47 g/cm^(3))and great stability of EMI shielding properties.This work offers a viable approach for craft-ing lightweight,highly shielding,and minimally reflective EMI shielding composites.展开更多
Continuous control protocols are extensively utilized in traditional MASs,in which information needs to be transmitted among agents consecutively,therefore resulting in excessive consumption of limited resources.To de...Continuous control protocols are extensively utilized in traditional MASs,in which information needs to be transmitted among agents consecutively,therefore resulting in excessive consumption of limited resources.To decrease the control cost,based on ISC,several LFC problems are investigated for second-order MASs without and with time delay,respectively.Firstly,an intermittent sampled controller is designed,and a sufficient and necessary condition is derived,under which state errors between the leader and all the followers approach zero asymptotically.Considering that time delay is inevitable,a new protocol is proposed to deal with the time-delay situation.The error system’s stability is analyzed using the Schur stability theorem,and sufficient and necessary conditions for LFC are obtained,which are closely associated with the coupling gain,the system parameters,and the network structure.Furthermore,for the case where the current position and velocity information are not available,a distributed protocol is designed that depends only on the sampled position information.The sufficient and necessary conditions for LFC are also given.The results show that second-order MASs can achieve the LFC if and only if the system parameters satisfy the inequalities proposed in the paper.Finally,the correctness of the obtained results is verified by numerical simulations.展开更多
Global challenges like epidemics,wars,and climate change expose humans to life-and-death threats daily,triggering death anxiety and subsequent death reflection,which involves deliberate cognitive processing of mortali...Global challenges like epidemics,wars,and climate change expose humans to life-and-death threats daily,triggering death anxiety and subsequent death reflection,which involves deliberate cognitive processing of mortality.While some studies have shown the positive impacts of death reflection,such as on well-being,the relationship between death reflection and existential well-being,closely related to life and death,remains unexplored.This study aimed to investigate the effects of death reflection on existential well-being and the mediating role of relational self-esteem.675 university students from Sichuan and Hubei,China,completed the death reflection scale,relational self-esteem scale,and the existential well-being subscale of the spiritual well-being scale.Results indicated that death reflection was positively correlated with both relational self-esteem and existential well-being,and relational self-esteem was positively related to existential well-being.Mediation analysis confirmed that relational self-esteem mediated the relationship between death reflection and existential well-being.This study not only enriches the research content on the positive effects of death reflection theoretically,but also holds significant practical value in guiding individuals who have experienced death or been exposed to death-related information in their psychological reconstruction and recovery.展开更多
In this paper,we investigate the phenomena of electromagnetically induced transparency and the generation of second-order sideband in a Laguerre–Gaussian cavity optorotational system with a Kerr nonlinear medium.Usin...In this paper,we investigate the phenomena of electromagnetically induced transparency and the generation of second-order sideband in a Laguerre–Gaussian cavity optorotational system with a Kerr nonlinear medium.Using the perturbation method,we analyze the first-and second-order sideband generations in the output field from the system under the actions of a strong control field and a weak probe field.Numerical simulations show that the Kerr nonlinearity can lead to the occurrence of the asymmetric line shape in the transmission of the probe field.Comparing with traditional scheme for generating the second-order sideband,our spectral shape of the second-order sideband is amplified and becomes asymmetric,which has potential applications in precision measurement,high-sensitivity devices,and frequency conversion.展开更多
We report an interesting and abnormal electromagnetic phenomenon with regard to a terajet(TJ)that is generated in a reflection mode,which is realized by placing a dielectric scatterer onto a metal reflection plate.We ...We report an interesting and abnormal electromagnetic phenomenon with regard to a terajet(TJ)that is generated in a reflection mode,which is realized by placing a dielectric scatterer onto a metal reflection plate.We show that the introduction of an air hollow into metal reflection plate beneath the scatterer does not induce an expected decrease but an abnormal increase of focal length of the TJ by as much as more than three times.This abnormal phenomenon takes place in case that the air hollow is shallow and there exists a critical hollow depth for a given lateral size of air hollow.Larger than the critical depth,the phenomenon no longer occurs.It is explained from viewpoints of both ray optics in terms of role of relative portion of central waves in TJ formation and electromagnetic field theory with regard to hollow-induced phase singularities.展开更多
Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodi...Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodicity.Here,we provide both numerical and analytical evidence that a depth gradient metasurface can achieve discrete ultra-broadband perfect anomalous reflection in the microwave range in the absence of geometric periodicity.Remarkably,by adjusting the operating frequency of the incident wave,the same effect can be steadily obtained via a physically equivalent phase periodicity in the PGM.Based on this mechanism,a perfect retroreflector with a broadband response ranging from 1 GHz to 40 GHz is realized.Our work has promising applications in communication,source tracking,and military satellites.展开更多
Curriculum ideological and political education is an important direction of higher education reform in the new era,aiming to realize the organic integration of professional knowledge imparting and ideological and poli...Curriculum ideological and political education is an important direction of higher education reform in the new era,aiming to realize the organic integration of professional knowledge imparting and ideological and political education.Taking preliminary landscape design course as an example,this paper expounded in detail the implementation of teaching reform from three aspects:the formulation of teaching objectives,the integration of teaching contents and the innovation of teaching methods.This paper systematically summarized the implementation effect of ideological and political education reform,and reflected on the excavation of ideological and political elements,integration degree,innovation of teaching methods,teachers’ideological and political ability and practical teaching.The exploration on curriculum ideological and political teaching provides useful reference and thinking for similar courses,and promotes the sustainable development of curriculum ideological and political education.展开更多
The power generation performance of a heaving body wave energy converter(HBWEC)can be enhanced through strategic deployment in proximity to natural or artificial coastal structures.In this study,coastal structures are...The power generation performance of a heaving body wave energy converter(HBWEC)can be enhanced through strategic deployment in proximity to natural or artificial coastal structures.In this study,coastal structures are represented by a partial reflection wall,enabling the device to harness additional reflected wave energy.However,the mechanisms by which the reflection coefficient and the clearance between the wall and the device affect energy conversion performance remain inadequately understood.This study experimentally investigates these effects.The findings demonstrate that the clearance impact on HBWEC power performance near partial reflection walls aligns with standing wave variation characteristics,with optimal positioning near the second antinode of the HBWEC's heaving natural period.Enhanced reflection coefficients improve energy conversion efficiency within the wave spectrum around the device's heaving natural period.Additionally,significant water sloshing observed within the clearance may diminish power performance,as verified through computational fluid dynamics(CFD)analysis.This phenomenon results from the multiplicative relationship of leeside clearance with 0.5λ(λis the wavelength).These insights suggest that practical engineering implementation requires balanced consideration of reflection coefficient,clearance,sloshing phenomenon,and heaving restriction system,rather than individual parameter optimization.展开更多
Polarization-dependent second harmonic generation is a widely utilized technique for characterizing symmetry.However,in collinear reflective geometry,the essential beam-splitting device significantly influences both t...Polarization-dependent second harmonic generation is a widely utilized technique for characterizing symmetry.However,in collinear reflective geometry,the essential beam-splitting device significantly influences both the polarization state of the fundamental and harmonic beams,thereby affecting the accuracy of the obtained second-order nonlinear susceptibility.Here,we propose a data correction method to solve this problem to obtain accurate secondorder nonlinear susceptibility.The feasibility and generality of the method are demonstrated through theoretical and experimental validation.展开更多
Reflection-based inversion that aims to reconstruct the low-to-intermediate wavenumbers of the subsurface model, can be a complementary to refraction-data-driven full-waveform inversion(FWI), especially for the deep t...Reflection-based inversion that aims to reconstruct the low-to-intermediate wavenumbers of the subsurface model, can be a complementary to refraction-data-driven full-waveform inversion(FWI), especially for the deep target area where diving waves cannot be acquired at the surface. Nevertheless, as a typical nonlinear inverse problem, reflection waveform inversion may easily suffer from the cycleskipping issue and have a slow convergence rate, if gradient-based first-order optimization methods are used. To improve the accuracy and convergence rate, we introduce the Hessian operator into reflection traveltime inversion(RTI) and reflection waveform inversion(RWI) in the framework of second-order optimization. A practical two-stage workflow is proposed to build the velocity model, in which Gauss-Newton RTI is first applied to mitigate the cycle-skipping problem and then Gauss-Newton RWI is employed to enhance the model resolution. To make the Gauss-Newton iterations more efficiently and robustly for large-scale applications, we introduce proper preconditioning for the Hessian matrix and design appropriate strategies to reduce the computational costs. The example of a real dataset from East China Sea demonstrates that the cascaded Hessian-based RTI and RWI have good potential to improve velocity model building and seismic imaging, especially for the deep targets.展开更多
Acoustic reflection imaging logging technology can detect and evaluate the development of reflection anomalies,such as fractures,caves and faults,within a range of tens of meters from the wellbore,greatly expanding th...Acoustic reflection imaging logging technology can detect and evaluate the development of reflection anomalies,such as fractures,caves and faults,within a range of tens of meters from the wellbore,greatly expanding the application scope of well logging technology.This article reviews the development history of the technology and focuses on introducing key methods,software,and on-site applications of acoustic reflection imaging logging technology.Based on the analyses of major challenges faced by existing technologies,and in conjunction with the practical production requirements of oilfields,the further development directions of acoustic reflection imaging logging are proposed.Following the current approach that utilizes the reflection coefficients,derived from the computation of acoustic slowness and density,to perform seismic inversion constrained by well logging,the next frontier is to directly establish the forward and inverse relationships between the downhole measured reflection waves and the surface seismic reflection waves.It is essential to advance research in imaging of fractures within shale reservoirs,the assessment of hydraulic fracturing effectiveness,the study of geosteering while drilling,and the innovation in instruments of acoustic reflection imaging logging technology.展开更多
Purpose – The vibration of the rails is a significant source of railway rolling noise, often forming the dominantcomponent of noise in the important frequency region between 400 and 2000 Hz. The purpose of the paper ...Purpose – The vibration of the rails is a significant source of railway rolling noise, often forming the dominantcomponent of noise in the important frequency region between 400 and 2000 Hz. The purpose of the paper is toinvestigate the influence of the ground profile and the presence of the train body on the sound radiation fromthe rail.Design/methodology/approach – Two-dimensional boundary element calculations are used, in which therail vibration is the source. The ground profile and various different shapes of train body are introduced in themodel, and results are observed in terms of sound power and sound pressure. Comparisons are also made withvibro-acoustic measurements performed with and without a train present.Findings – The sound radiated by the rail in the absence of the train body is strongly attenuated by shieldingdue to the ballast shoulder. When the train body is present, the sound from the vertical rail motion is reflectedback down toward the track where it is partly absorbed by the ballast. Nevertheless, the sound pressure at thetrackside is increased by typically 0–5 dB. For the lateral vibration of the rail, the effects are much smaller. Oncethe sound power is known, the sound pressure with the train present can be approximated reasonably well withsimple line source directivities.Originality/value – Numerical models used to predict the sound radiation from railway rails have generallyneglected the influence of the ground profile and reflections from the underside of the train body on the soundpower and directivity of the rail. These effects are studied in a systematic way including comparisons with measurements.展开更多
In this editorial,I present my comments on the article by Solarino et al.Conversion hip arthroplasty,which is an optional salvage procedure performed following unsuccessful fixation of intertrochanteric femur fracture...In this editorial,I present my comments on the article by Solarino et al.Conversion hip arthroplasty,which is an optional salvage procedure performed following unsuccessful fixation of intertrochanteric femur fractures in elderly pati-ents,entails more complex processes and higher rates of operative complications than primary arthroplasty.Hence,it is important to consider the appropriateness of the primary treatment choice,as well as the adequacy of nailing fixation for intertrochanteric fractures.This article briefly analyzes the possible factors contributing to the nailing failure of intertrochanteric fractures and attempts to find corresponding countermeasures to prevent fixation failures.It also analyzes the choice of treatment between nailing fixation and primary arthroplasty for intertrochanteric fractures.展开更多
We theoretically study the effect of Kerr effect on the second-order nonlinearity induced transparency in a double-resonant optical cavity system.We show that in the presence of the Kerr effect,as the strength of the ...We theoretically study the effect of Kerr effect on the second-order nonlinearity induced transparency in a double-resonant optical cavity system.We show that in the presence of the Kerr effect,as the strength of the Kerr effect increases,the absorption curve exhibits an asymmetric-symmetric-asymmetric transition,and the zero absorption point shifts with the increase of the Kerr effect.Furthermore,by changing the strength of the Kerr effect,we can control the width of the transparent window,and the position of the zero-absorption point and meanwhile change the left and right width of the absorption peak.The asymmetry absorption curve can be employed to improve the quality factor of the cavity when the frequency detuning is tuned to be around the right peak.The simple dependence of the zeroabsorption point on the strength of Kerr effect suggests that the strength of Kerr effect can be measured by measuring the position of the zero-absorption point in a possible application.展开更多
Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a&#...Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by SAM.The RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic principle.By comparing with the Raman spectrum,it is verified that the micropipes consist of edge dislocations.The different patterns of the RA images are due to the different orientations of the Burgers vectors.Besides,the strain distribution of the micropipes is also deduced.One can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using SAM.Therefore,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect.展开更多
Reducing the control error is vital for high-fidelity digital and analog quantum operations.In superconducting circuits,one disagreeable error arises from the reflection of microwave signals due to impedance mismatch ...Reducing the control error is vital for high-fidelity digital and analog quantum operations.In superconducting circuits,one disagreeable error arises from the reflection of microwave signals due to impedance mismatch in the control chain.Here,we demonstrate a reflection cancelation method when considering that there are two reflection nodes on the control line.We propose to generate the pre-distortion pulse by passing the envelopes of the microwave signal through digital filters,which enables real-time reflection correction when integrated into the field-programmable gate array(FPGA).We achieve a reduction of single-qubit gate infidelity from 0.67%to 0.11%after eliminating microwave reflection.Real-time correction of microwave reflection paves the way for precise control and manipulation of the qubit state and would ultimately enhance the performance of algorithms and simulations executed on quantum processors.展开更多
The field of terahertz devices is important in terahertz technology.However,most of the current devices have limited functionality and poor performance.To improve device performance and achieve multifunctionality,we d...The field of terahertz devices is important in terahertz technology.However,most of the current devices have limited functionality and poor performance.To improve device performance and achieve multifunctionality,we designed a terahertz device based on a combination of VO_(2)and metamaterials.This device can be tuned using the phase-transition characteristics of VO_(2),which is included in the triple-layer structure of the device,along with SiO_(2)and Au.The terahertz device exhibits various advantageous features,including broadband coverage,high absorption capability,dynamic tunability,simple structural design,polarization insensitivity,and incidentangle insensitivity.The simulation results showed that by controlling the temperature,the terahertz device achieved a thermal modulation range of spectral absorption from 0 to 0.99.At 313 K,the device exhibited complete reflection of terahertz waves.As the temperature increased,the absorption rate also increased.When the temperature reached 353 K,the device absorption rate exceeded 97.7%in the range of 5-8.55 THz.This study used the effective medium theory to elucidate the correlation between conductivity and temperature during the phase transition of VO_(2).Simultaneously,the variation in device performance was further elucidated by analyzing and depicting the intensity distribution of the electric field on the device surface at different temperatures.Furthermore,the impact of various structural parameters on device performance was examined,offering valuable insights and suggestions for selecting suitable parameter values in real-world applications.These characteristics render the device highly promising for applications in stealth technology,energy harvesting,modulation,and other related fields,thus showcasing its significant potential.展开更多
基金supported by the Natural Science Foundation of Anhui Province(No.2308085QE146 and 2208085ME116)the National Natural Science Foundation of China(No.52173039)+1 种基金the Natural Science Foundation of Jiangsu Province(No.BK20210894)the Anhui Provincial Universities Outstanding Youth Research Project(No.2023AH020018).
文摘Electromagnetic interference(EMI)shielding materials with superior shielding efficiency and low-reflection properties hold promising potential for utilization across electronic components,precision instruments,and fifth-generation communication equipment.In this study,multistage microcellular waterborne polyurethane(WPU)composites were constructed via gradient induction,layer-by-layer casting,and supercritical carbon dioxide foaming.The gradient-structured WPU/ironcobalt loaded reduced graphene oxide(FeCo@rGO)foam serves as an impedance-matched absorption layer,while the highly conductive WPU/silver loaded glass microspheres(Ag@GM)layer is employed as a reflection layer.Thanks to the incorporation of an asymmetric structure,as well as the introduction of gradient and porous configurations,the composite foam demonstrates excellent conductivity,outstanding EMI SE(74.9 dB),and minimal reflection characteristics(35.28%)in 8.2-12.4 GHz,implying that more than 99.99999%of electromagnetic(EM)waves were blocked and only 35.28%were reflected to the external environment.Interestingly,the reflectivity of the composite foam is reduced to 0.41%at 10.88 GHz due to the resonance for incident and reflected EM waves.Beyond that,the composite foam is characterized by low density(0.47 g/cm^(3))and great stability of EMI shielding properties.This work offers a viable approach for craft-ing lightweight,highly shielding,and minimally reflective EMI shielding composites.
基金supported by the National Natural Science Foundation of China under Grants 62476138 and 42375016.
文摘Continuous control protocols are extensively utilized in traditional MASs,in which information needs to be transmitted among agents consecutively,therefore resulting in excessive consumption of limited resources.To decrease the control cost,based on ISC,several LFC problems are investigated for second-order MASs without and with time delay,respectively.Firstly,an intermittent sampled controller is designed,and a sufficient and necessary condition is derived,under which state errors between the leader and all the followers approach zero asymptotically.Considering that time delay is inevitable,a new protocol is proposed to deal with the time-delay situation.The error system’s stability is analyzed using the Schur stability theorem,and sufficient and necessary conditions for LFC are obtained,which are closely associated with the coupling gain,the system parameters,and the network structure.Furthermore,for the case where the current position and velocity information are not available,a distributed protocol is designed that depends only on the sampled position information.The sufficient and necessary conditions for LFC are also given.The results show that second-order MASs can achieve the LFC if and only if the system parameters satisfy the inequalities proposed in the paper.Finally,the correctness of the obtained results is verified by numerical simulations.
文摘Global challenges like epidemics,wars,and climate change expose humans to life-and-death threats daily,triggering death anxiety and subsequent death reflection,which involves deliberate cognitive processing of mortality.While some studies have shown the positive impacts of death reflection,such as on well-being,the relationship between death reflection and existential well-being,closely related to life and death,remains unexplored.This study aimed to investigate the effects of death reflection on existential well-being and the mediating role of relational self-esteem.675 university students from Sichuan and Hubei,China,completed the death reflection scale,relational self-esteem scale,and the existential well-being subscale of the spiritual well-being scale.Results indicated that death reflection was positively correlated with both relational self-esteem and existential well-being,and relational self-esteem was positively related to existential well-being.Mediation analysis confirmed that relational self-esteem mediated the relationship between death reflection and existential well-being.This study not only enriches the research content on the positive effects of death reflection theoretically,but also holds significant practical value in guiding individuals who have experienced death or been exposed to death-related information in their psychological reconstruction and recovery.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174344 and 12175199)Foundation of Department of Science and Technology of Zhejiang Province(Grant No.2022R52047)。
文摘In this paper,we investigate the phenomena of electromagnetically induced transparency and the generation of second-order sideband in a Laguerre–Gaussian cavity optorotational system with a Kerr nonlinear medium.Using the perturbation method,we analyze the first-and second-order sideband generations in the output field from the system under the actions of a strong control field and a weak probe field.Numerical simulations show that the Kerr nonlinearity can lead to the occurrence of the asymmetric line shape in the transmission of the probe field.Comparing with traditional scheme for generating the second-order sideband,our spectral shape of the second-order sideband is amplified and becomes asymmetric,which has potential applications in precision measurement,high-sensitivity devices,and frequency conversion.
基金Project supported by the National Natural Science Foundation of China(Grant No.61875148)the Key Awards Program of Cultivating Outstanding Innovative Postgraduates in Arts and Sciences of Tianjin University(Grant No.C1-2022002)+3 种基金the Talent Project of Anhui Science and Technology University(Grant No.DQYJ202304)the University-Level Research Project of Tianjin Sino-German University of Applied Sciences(Grant No.zdkt2018-007)China Association for Science and Technology Young Talent Support Project Doctoral Special Programthe National High-level University Scholarship Program for Graduate Students of China Scholarship Council(Grant No.202406250166)。
文摘We report an interesting and abnormal electromagnetic phenomenon with regard to a terajet(TJ)that is generated in a reflection mode,which is realized by placing a dielectric scatterer onto a metal reflection plate.We show that the introduction of an air hollow into metal reflection plate beneath the scatterer does not induce an expected decrease but an abnormal increase of focal length of the TJ by as much as more than three times.This abnormal phenomenon takes place in case that the air hollow is shallow and there exists a critical hollow depth for a given lateral size of air hollow.Larger than the critical depth,the phenomenon no longer occurs.It is explained from viewpoints of both ray optics in terms of role of relative portion of central waves in TJ formation and electromagnetic field theory with regard to hollow-induced phase singularities.
基金supported by the National Natural Science Foundation of China(Grant Nos.12274313,62275184,and 62411540033)Collaborative Innovation Center of Suzhou Nano Science and Technology,Suzhou Basic Research Project(Grant No.SJC2023003)+1 种基金the Gusu Leading Talent Plan for Scientific and Technological Innovation and Entrepreneurship(Grant No.ZXL2024400)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodicity.Here,we provide both numerical and analytical evidence that a depth gradient metasurface can achieve discrete ultra-broadband perfect anomalous reflection in the microwave range in the absence of geometric periodicity.Remarkably,by adjusting the operating frequency of the incident wave,the same effect can be steadily obtained via a physically equivalent phase periodicity in the PGM.Based on this mechanism,a perfect retroreflector with a broadband response ranging from 1 GHz to 40 GHz is realized.Our work has promising applications in communication,source tracking,and military satellites.
基金Sponsored by Teaching Research Project of Yangtze University(JY2023028).
文摘Curriculum ideological and political education is an important direction of higher education reform in the new era,aiming to realize the organic integration of professional knowledge imparting and ideological and political education.Taking preliminary landscape design course as an example,this paper expounded in detail the implementation of teaching reform from three aspects:the formulation of teaching objectives,the integration of teaching contents and the innovation of teaching methods.This paper systematically summarized the implementation effect of ideological and political education reform,and reflected on the excavation of ideological and political elements,integration degree,innovation of teaching methods,teachers’ideological and political ability and practical teaching.The exploration on curriculum ideological and political teaching provides useful reference and thinking for similar courses,and promotes the sustainable development of curriculum ideological and political education.
基金supported by the National Natural Science Foundation of China(Grant Nos.52201322,52401323,and52222109)the Fundamental Research Funds for the Central Universities(Grant No.2024ZYGXZR042)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022B1515020036 and 2023A1515012144)the Project of State Key Laboratory of Subtropical Building and Urban Science(Grant No.2023ZB14)。
文摘The power generation performance of a heaving body wave energy converter(HBWEC)can be enhanced through strategic deployment in proximity to natural or artificial coastal structures.In this study,coastal structures are represented by a partial reflection wall,enabling the device to harness additional reflected wave energy.However,the mechanisms by which the reflection coefficient and the clearance between the wall and the device affect energy conversion performance remain inadequately understood.This study experimentally investigates these effects.The findings demonstrate that the clearance impact on HBWEC power performance near partial reflection walls aligns with standing wave variation characteristics,with optimal positioning near the second antinode of the HBWEC's heaving natural period.Enhanced reflection coefficients improve energy conversion efficiency within the wave spectrum around the device's heaving natural period.Additionally,significant water sloshing observed within the clearance may diminish power performance,as verified through computational fluid dynamics(CFD)analysis.This phenomenon results from the multiplicative relationship of leeside clearance with 0.5λ(λis the wavelength).These insights suggest that practical engineering implementation requires balanced consideration of reflection coefficient,clearance,sloshing phenomenon,and heaving restriction system,rather than individual parameter optimization.
基金This work was supported by the National Natural Science Foundation of China(No.U2230203)the Fundamental Research Funds for the Central Universities.
文摘Polarization-dependent second harmonic generation is a widely utilized technique for characterizing symmetry.However,in collinear reflective geometry,the essential beam-splitting device significantly influences both the polarization state of the fundamental and harmonic beams,thereby affecting the accuracy of the obtained second-order nonlinear susceptibility.Here,we propose a data correction method to solve this problem to obtain accurate secondorder nonlinear susceptibility.The feasibility and generality of the method are demonstrated through theoretical and experimental validation.
基金supported by National Natural Science Foundation of China (42074157)the National Key Research and Development Program of China (2018YFC0310104)the Strategic Priority Research Program of the Chinese Academy of Science(XDA14010203)。
文摘Reflection-based inversion that aims to reconstruct the low-to-intermediate wavenumbers of the subsurface model, can be a complementary to refraction-data-driven full-waveform inversion(FWI), especially for the deep target area where diving waves cannot be acquired at the surface. Nevertheless, as a typical nonlinear inverse problem, reflection waveform inversion may easily suffer from the cycleskipping issue and have a slow convergence rate, if gradient-based first-order optimization methods are used. To improve the accuracy and convergence rate, we introduce the Hessian operator into reflection traveltime inversion(RTI) and reflection waveform inversion(RWI) in the framework of second-order optimization. A practical two-stage workflow is proposed to build the velocity model, in which Gauss-Newton RTI is first applied to mitigate the cycle-skipping problem and then Gauss-Newton RWI is employed to enhance the model resolution. To make the Gauss-Newton iterations more efficiently and robustly for large-scale applications, we introduce proper preconditioning for the Hessian matrix and design appropriate strategies to reduce the computational costs. The example of a real dataset from East China Sea demonstrates that the cascaded Hessian-based RTI and RWI have good potential to improve velocity model building and seismic imaging, especially for the deep targets.
基金Supported by the PetroChina Science and Technology Project(2021DJ4002,2022DJ3908)。
文摘Acoustic reflection imaging logging technology can detect and evaluate the development of reflection anomalies,such as fractures,caves and faults,within a range of tens of meters from the wellbore,greatly expanding the application scope of well logging technology.This article reviews the development history of the technology and focuses on introducing key methods,software,and on-site applications of acoustic reflection imaging logging technology.Based on the analyses of major challenges faced by existing technologies,and in conjunction with the practical production requirements of oilfields,the further development directions of acoustic reflection imaging logging are proposed.Following the current approach that utilizes the reflection coefficients,derived from the computation of acoustic slowness and density,to perform seismic inversion constrained by well logging,the next frontier is to directly establish the forward and inverse relationships between the downhole measured reflection waves and the surface seismic reflection waves.It is essential to advance research in imaging of fractures within shale reservoirs,the assessment of hydraulic fracturing effectiveness,the study of geosteering while drilling,and the innovation in instruments of acoustic reflection imaging logging technology.
基金supported by the TRANSIT project(funded by EU Horizon 2020 and the Europe’s Rail Joint Undertaking under Grant Agreement 881771).
文摘Purpose – The vibration of the rails is a significant source of railway rolling noise, often forming the dominantcomponent of noise in the important frequency region between 400 and 2000 Hz. The purpose of the paper is toinvestigate the influence of the ground profile and the presence of the train body on the sound radiation fromthe rail.Design/methodology/approach – Two-dimensional boundary element calculations are used, in which therail vibration is the source. The ground profile and various different shapes of train body are introduced in themodel, and results are observed in terms of sound power and sound pressure. Comparisons are also made withvibro-acoustic measurements performed with and without a train present.Findings – The sound radiated by the rail in the absence of the train body is strongly attenuated by shieldingdue to the ballast shoulder. When the train body is present, the sound from the vertical rail motion is reflectedback down toward the track where it is partly absorbed by the ballast. Nevertheless, the sound pressure at thetrackside is increased by typically 0–5 dB. For the lateral vibration of the rail, the effects are much smaller. Oncethe sound power is known, the sound pressure with the train present can be approximated reasonably well withsimple line source directivities.Originality/value – Numerical models used to predict the sound radiation from railway rails have generallyneglected the influence of the ground profile and reflections from the underside of the train body on the soundpower and directivity of the rail. These effects are studied in a systematic way including comparisons with measurements.
文摘In this editorial,I present my comments on the article by Solarino et al.Conversion hip arthroplasty,which is an optional salvage procedure performed following unsuccessful fixation of intertrochanteric femur fractures in elderly pati-ents,entails more complex processes and higher rates of operative complications than primary arthroplasty.Hence,it is important to consider the appropriateness of the primary treatment choice,as well as the adequacy of nailing fixation for intertrochanteric fractures.This article briefly analyzes the possible factors contributing to the nailing failure of intertrochanteric fractures and attempts to find corresponding countermeasures to prevent fixation failures.It also analyzes the choice of treatment between nailing fixation and primary arthroplasty for intertrochanteric fractures.
基金Supported by the Key Scientific Research Plan of Colleges and Universities in Henan Province(23B140006)the National Natural Science Foundation of China(11965017)。
文摘We theoretically study the effect of Kerr effect on the second-order nonlinearity induced transparency in a double-resonant optical cavity system.We show that in the presence of the Kerr effect,as the strength of the Kerr effect increases,the absorption curve exhibits an asymmetric-symmetric-asymmetric transition,and the zero absorption point shifts with the increase of the Kerr effect.Furthermore,by changing the strength of the Kerr effect,we can control the width of the transparent window,and the position of the zero-absorption point and meanwhile change the left and right width of the absorption peak.The asymmetry absorption curve can be employed to improve the quality factor of the cavity when the frequency detuning is tuned to be around the right peak.The simple dependence of the zeroabsorption point on the strength of Kerr effect suggests that the strength of Kerr effect can be measured by measuring the position of the zero-absorption point in a possible application.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFE0204001,2018YFA0209103,2016YFB0400101,and 2016YFB0402303)the National Natural Science Foundation of China(Grant Nos.61627822,61704121,61991430,and 62074036)Postdoctoral Research Program of Jiangsu Province(Grant No.2021K599C).
文摘Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by SAM.The RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic principle.By comparing with the Raman spectrum,it is verified that the micropipes consist of edge dislocations.The different patterns of the RA images are due to the different orientations of the Burgers vectors.Besides,the strain distribution of the micropipes is also deduced.One can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using SAM.Therefore,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect.
基金the National Natural Science Foun-dation of China(Grant Nos.12034018 and 11625419).
文摘Reducing the control error is vital for high-fidelity digital and analog quantum operations.In superconducting circuits,one disagreeable error arises from the reflection of microwave signals due to impedance mismatch in the control chain.Here,we demonstrate a reflection cancelation method when considering that there are two reflection nodes on the control line.We propose to generate the pre-distortion pulse by passing the envelopes of the microwave signal through digital filters,which enables real-time reflection correction when integrated into the field-programmable gate array(FPGA).We achieve a reduction of single-qubit gate infidelity from 0.67%to 0.11%after eliminating microwave reflection.Real-time correction of microwave reflection paves the way for precise control and manipulation of the qubit state and would ultimately enhance the performance of algorithms and simulations executed on quantum processors.
基金support from the National Natural Science Foundation of China(Nos.51606158,11604311,and 12074151)Sichuan Science and Technology Program(No.2021JDRC0022)+3 种基金Natural Science Foundation of Fujian Province(No.2021J05202)Research Project of Fashu Foundation(No.MFK23006)Open Fund of the Key Laboratory of Metallurgical Equipment and Control Technology of Ministry of Education in Wuhan University of Science and Technology(No.MECOF2022B01)the project supported by Guangxi Key Laboratory of Precision Navigation Technology and Application,Guilin University of Electronic Technology(No.DH202321).
文摘The field of terahertz devices is important in terahertz technology.However,most of the current devices have limited functionality and poor performance.To improve device performance and achieve multifunctionality,we designed a terahertz device based on a combination of VO_(2)and metamaterials.This device can be tuned using the phase-transition characteristics of VO_(2),which is included in the triple-layer structure of the device,along with SiO_(2)and Au.The terahertz device exhibits various advantageous features,including broadband coverage,high absorption capability,dynamic tunability,simple structural design,polarization insensitivity,and incidentangle insensitivity.The simulation results showed that by controlling the temperature,the terahertz device achieved a thermal modulation range of spectral absorption from 0 to 0.99.At 313 K,the device exhibited complete reflection of terahertz waves.As the temperature increased,the absorption rate also increased.When the temperature reached 353 K,the device absorption rate exceeded 97.7%in the range of 5-8.55 THz.This study used the effective medium theory to elucidate the correlation between conductivity and temperature during the phase transition of VO_(2).Simultaneously,the variation in device performance was further elucidated by analyzing and depicting the intensity distribution of the electric field on the device surface at different temperatures.Furthermore,the impact of various structural parameters on device performance was examined,offering valuable insights and suggestions for selecting suitable parameter values in real-world applications.These characteristics render the device highly promising for applications in stealth technology,energy harvesting,modulation,and other related fields,thus showcasing its significant potential.
