As the U.S.continues its proxy war with Russia in Ukraine and its escalation with China in the Asia-Pacific,the U.S.is also targeting a number of nationsnot only across Eurasia,but also far beyondit,including the Lati...As the U.S.continues its proxy war with Russia in Ukraine and its escalation with China in the Asia-Pacific,the U.S.is also targeting a number of nationsnot only across Eurasia,but also far beyondit,including the Latin American nation of Venezuela.展开更多
Amid overlapping crises and uncertainties as the world enters an era of turbulence and transformation,the countries of the Global South are swiftly emerging from the periphery of world politics to the forefront of int...Amid overlapping crises and uncertainties as the world enters an era of turbulence and transformation,the countries of the Global South are swiftly emerging from the periphery of world politics to the forefront of international cooperation,playing an increasingly vital role in advancing humanity’s collective progress.展开更多
As the accelerated changes on a scale unprecedented in a century are unfolding across the world,multipolarity of the international system is increasingly accepted as a fundamental trend.As a unique international actor...As the accelerated changes on a scale unprecedented in a century are unfolding across the world,multipolarity of the international system is increasingly accepted as a fundamental trend.As a unique international actor,the European Union,despite its initial strategic anxiety about multipolarity,has gradually come to terms with the growing reality of multipolarity and adjusted its foreign strategy to become one of the poles in the multipolar world.展开更多
China-Africa cooperation sets a benchmark for equitable development in a multipolar world Despite rising unilateralism and protectionism in the West and increasing uncertainties in global trade,China-Africa economic a...China-Africa cooperation sets a benchmark for equitable development in a multipolar world Despite rising unilateralism and protectionism in the West and increasing uncertainties in global trade,China-Africa economic and trade cooperation remains on a fast track,backed by concrete actions towards common modernisation.This collaboration reinforces solidarity across the Global South and contributes to greater stability and confidence in the global multilateral trading system.展开更多
The global clustering of inventive talent shapes innovation capacity and drives economic growth.For China,this process is especially crucial in sustaining its development momentum.This paper draws on data from the EPO...The global clustering of inventive talent shapes innovation capacity and drives economic growth.For China,this process is especially crucial in sustaining its development momentum.This paper draws on data from the EPO Worldwide Patent Statistical Database(PATSTAT)to extract global inventive talent mobility information and analyzes the spatial structural evolution of the global inventive talent flow network.The study finds that this network is undergoing a multi-polar transformation,characterized by the rising importance of a few central countries-such as the United States,Germany,and China-and the increasing marginalization of many peripheral countries.In response to this typical phenomenon,the paper constructs an endogenous migration model and conducts empirical testing using the Temporal Exponential Random Graph Model(TERGM).The results reveal several endogenous mechanisms driving global inventive talent flows,including reciprocity,path dependence,convergence effects,transitivity,and cyclic structures,all of which contribute to the network’s multi-polar trend.In addition,differences in regional industrial structures significantly influence talent mobility choices and are a decisive factor in the formation of poles within the multi-polar landscape.Based on these findings,it is suggested that efforts be made to foster two-way channels for talent exchange between China and other global innovation hubs,in order to enhance international collaboration and knowledge flow.We should aim to reduce the migration costs and institutional barriers faced by R&D personnel,thereby encouraging greater mobility of high-skilled talent.Furthermore,the government is advised to strategically leverage regional strengths in high-tech industries as a lever to capture competitive advantages in emerging technologies and products,ultimately strengthening the country’s position in the global innovation landscape.展开更多
Nanofluids or liquids with suspended nanoparticles are likely to be the future heat transfer media, as they exhibit higher thermal conductivity than those of liquids. It has been proposed that nanoparticles are apt to...Nanofluids or liquids with suspended nanoparticles are likely to be the future heat transfer media, as they exhibit higher thermal conductivity than those of liquids. It has been proposed that nanoparticles are apt to congregate and form clusters, and hence the interaction between nanoparticles becomes important. In this paper, by taking into account the interaction between nearest-neighbour inclusions, we adopt the multiple image method to investigate the effective thermal conductivity of nanofluids. Numerical results show that then the thermal conductivity ratio between the nanoparticles and fluids is large, and the two nanoparticles are close up and even touch, and the polnt-dipole theory such as Maxwell-Garnett theory becomes rough as many-body interactions are neglected. Our theoretical results on the effective thermal conductivity of CuO/water and Al2O3/water nanofluids are in good agreement with experimental data.展开更多
A sputtering-type microwave multipolar ECR plasma processing for preparing thin films, is built with Nd-Fe-B magnets and 2.45 GHz, TE<sub>10</sub> mode microwave. The plasma distributions in the axial dire...A sputtering-type microwave multipolar ECR plasma processing for preparing thin films, is built with Nd-Fe-B magnets and 2.45 GHz, TE<sub>10</sub> mode microwave. The plasma distributions in the axial direction, which is important for preparing thin films, are found to be very sensitive to the magnetic potential fields in plasma chamber. The plasma parameters are also influenced by the background gas pressure.展开更多
The acoustic focusing effect of metamaterial has a wide range of applications in medicine,acoustic imaging,signal detection,etc.This paper presents an acoustic metamaterial applied to the acoustic focusing effect.The ...The acoustic focusing effect of metamaterial has a wide range of applications in medicine,acoustic imaging,signal detection,etc.This paper presents an acoustic metamaterial applied to the acoustic focusing effect.The formation of acousticmetamaterial is designed into a cylindrical structure with three layers of ludox,cork and fluid rubber,which can produce a focusingphenomenon when acoustic waves propagate in air.For these strange phenomena,a scientific description is given theorietically.It can also be concluded that when the frequency of the incident acoustic wave increases?the number of peripheral bandsoutside the focusing poles will increase periodically.Besides,there are numerous groups of multipolar focusing phenomena inhigh frequency.The design of this acoustic metamaterial is successful through theorietical and experimental verification,therefore,it can be applied to acoustic communication and test.展开更多
Research of the acoustic local effect of metamaterial is widely used in the fields of environmental science,military industry and biomedicine.In this paper,the metamaterial is designed by annular columnar structures.T...Research of the acoustic local effect of metamaterial is widely used in the fields of environmental science,military industry and biomedicine.In this paper,the metamaterial is designed by annular columnar structures.The acoustic local effect in slender columnar structure with two layers of rings in air is investigated.Results prove that when the plane acoustic wave is incident into the model,complex interference and diffraction occur.And at different frequencies,multipolar acoustic local effect existes and cycle distribution phenomenon is observed.It is noteworthy that this phenomenon has very weak relatedness with the materials and acoustic parameters of the model.The research of this metamaterial design in this paper has definite reference significance in the acoustic communication and amplification of the acoustic signal detection.展开更多
The multipolar velocity field structures are investigated by 2D momentum conservation equation with 3D equilibrium sheared flows in the full toroidal system. Numerical results show that the non-existence of radial vel...The multipolar velocity field structures are investigated by 2D momentum conservation equation with 3D equilibrium sheared flows in the full toroidal system. Numerical results show that the non-existence of radial velocity field in equilibrium surfaces is suitable only for the zero-order term of our 2D simulation. The non-zero-order radial velocity field is still preserved, even when converted to conventional magnetic surface coordinates. The distribution of velocity field vectors of the order of 1, 2, and 3 are presented respectively in 2, 4, and 6 polar fields with the local vortex structure. The excitation mechanisms of these velocity vortices are the coupling effects of the magneto-fluid structure patterns and the toroidal effects. These results can help us understand the complexity of core physics, the transverse transport across magnetic field by the radial plasma flow and the formation of velocity vortices.展开更多
The multipolar magnetic field structure is investigated by the momentum conservation equation with self-c on sistent 3D sheared flows during transition of plasma properties from local paramagnetic to diamagnelic field...The multipolar magnetic field structure is investigated by the momentum conservation equation with self-c on sistent 3D sheared flows during transition of plasma properties from local paramagnetic to diamagnelic fields.Numerical results show that the traditional poloidal magnetic field(Bp)is one part of equilibrium magnetic fields.The non-zero-order quantities are originaled from the higher-order terms of 2D equilibrium treatment based on a Fourier expansion of 0(r,0).The distributions of magnetic field vectors of the order of 1,2,and 3 terms are presented respectively in two.four,and six polar fields with the local vortex structures(spontaneous magnetic conn ection).The excitation mechanisms of the magnetic vortices are the coupling effects of the magnetic fluid structure pattern and the toroidal effects.These results can help us understand the physical mechanism of the in teraction between the external perturbation fields and control tearing modes,as well as the radial plasma flow and magnetic vortices.展开更多
The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence...The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence-shell excitations in 4d, 4f, 5p, 5d, 6s, 6p, 7s ←4p of krypton atom have been determined. Their profiles are discussed, and the generalized oscillator strengths for the electric monopole and quadrupole excitations in 5p ← 4p are compared with the calculations of Amusia et al. （Phys. Rev. A 67 022703 （2003））. The differences between the experimental results and theoretical calculations show that more studies are needed.展开更多
The pursuit of a systematic frequency uncertainty beyond 10^(-18) clock has triggered a multitude of investigations on the multipolar and higher-order lattice light shifts.The Cd atom has been proposed as a new candid...The pursuit of a systematic frequency uncertainty beyond 10^(-18) clock has triggered a multitude of investigations on the multipolar and higher-order lattice light shifts.The Cd atom has been proposed as a new candidate for the development of a lattice clock because of its smaller blackbody radiation shift at room temperature.Here,we apply an improved combined method of the Dirac-Fock plus core polarization and relativistic configuration interaction methods to calculate the dynamic multipolar polarizabilities of the Cd clock states.The effects of the high-order core-polarization potentials on the energies,reduced matrix elements,and multipolar polarizabilities have been evaluated systematically.The detailed comparison with available literature demonstrates that taking into account of the high-order core-polarization potentials is a simple and effective approach to improve the results of atomic properties for heavy atoms.展开更多
A new method for plasma boundary reconstruction, based on the toroidal multipolar expansion （TME） scheme, is applied successfully in EAST. TME applies a limited number of toroidal multipolar moments based on toroida...A new method for plasma boundary reconstruction, based on the toroidal multipolar expansion （TME） scheme, is applied successfully in EAST. TME applies a limited number of toroidal multipolar moments based on toroidal coordinates to treat a two-dimensional problem of axisymmetric plasma equilibrium. The plasma boundary reconstructed by TME is consistent with the results by using EFIT. The method is sufficiently reliable and fast for real time shape control.展开更多
Purpose: Pulmonary vein isolation (PVI) is the accepted primary endpoint for catheter ablation of atrial fibrillation (AF). The aim of this study was to evaluate the level of PVI by PVAC, a multipolar circular cathete...Purpose: Pulmonary vein isolation (PVI) is the accepted primary endpoint for catheter ablation of atrial fibrillation (AF). The aim of this study was to evaluate the level of PVI by PVAC, a multipolar circular catheter utilizing bipolar/unipolar radiofrequency (RF) energy. Methods: Twenty patients with paroxysmal AF underwent PVAC ablation. PVI was validated by voltage reduction and pacing tests. Before and after RF ablation, left atrium (LA) and PV electroanatomic mapping (EAM) were performed by EnSite NavX system. Voltage abatement was considered for potentials 24mm: 9/20 (45%) vs 11/57 (19%),展开更多
The words that Xi Jinping said at the 47th World Economic Forum(WEF)have really surprised just the most inattentive people.During his visit to Davos,where leaders,entrepreneurs
At present,changes of great consequence for our world are unfolding in unprecedented ways.These changes present both strategic opportunities and serious challenges.Confronting the critical global issues facing the wor...At present,changes of great consequence for our world are unfolding in unprecedented ways.These changes present both strategic opportunities and serious challenges.Confronting the critical global issues facing the world today,such as the deficits in peace,development,security,and governance.展开更多
Spatiotemporal optical vortices(STOVs)exhibit characteristics of transverse orbital angular momentum(OAM)that is perpendicular to the direction of pulse propagation,indicating significant potential for diverse applica...Spatiotemporal optical vortices(STOVs)exhibit characteristics of transverse orbital angular momentum(OAM)that is perpendicular to the direction of pulse propagation,indicating significant potential for diverse applications.In this study,we employ vanadium dioxide and photonic crystal plates to design tunable transreflective dual-channel terahertz(THz)spatiotemporal vortex generation devices that possess multipolarization adaptability.In the reflection channel,we achieve active tunability of the topological dark lines by utilizing circularly polarized light,based on the topological dark phenomenon,and observe variations in the number of singularities across the parameter space from different observational perspectives.In the transmission channel,we generate independent vortex singularities using linearly polarized light.This multifunctional terahertz device offers a novel approach for the generation and active tuning of spatiotemporal vortices.展开更多
China and India mark 75 years of diplomatic ties,reflecting on past challenges and achievements while focusing on stabilization,cooperation and shaping a multipolar global future.
This analysis explores China's quest for international legitimacy through its leadership in the BRICS+expansion,a strategic maneuver to foster a multipolar world that integrates diverse political and economic syst...This analysis explores China's quest for international legitimacy through its leadership in the BRICS+expansion,a strategic maneuver to foster a multipolar world that integrates diverse political and economic systems.The evolution into BRICS+is significant,with the collective GDP of member countries reaching $30.76 trillion,accounting for 30% of the global economy.This underscores the alliance's economic impact and challenges the existing world order.The inclusion of nations like Saudi Arabia,Iran,Ethiopia,Egypt,and the UAE offers a blueprint for shared benefits and mutual growth.China advocates for an alternative,inclusive pathway to legitimacy,promoting a world order that values sovereignty,cultural identity,and balanced global governance.展开更多
文摘As the U.S.continues its proxy war with Russia in Ukraine and its escalation with China in the Asia-Pacific,the U.S.is also targeting a number of nationsnot only across Eurasia,but also far beyondit,including the Latin American nation of Venezuela.
文摘Amid overlapping crises and uncertainties as the world enters an era of turbulence and transformation,the countries of the Global South are swiftly emerging from the periphery of world politics to the forefront of international cooperation,playing an increasingly vital role in advancing humanity’s collective progress.
文摘As the accelerated changes on a scale unprecedented in a century are unfolding across the world,multipolarity of the international system is increasingly accepted as a fundamental trend.As a unique international actor,the European Union,despite its initial strategic anxiety about multipolarity,has gradually come to terms with the growing reality of multipolarity and adjusted its foreign strategy to become one of the poles in the multipolar world.
文摘China-Africa cooperation sets a benchmark for equitable development in a multipolar world Despite rising unilateralism and protectionism in the West and increasing uncertainties in global trade,China-Africa economic and trade cooperation remains on a fast track,backed by concrete actions towards common modernisation.This collaboration reinforces solidarity across the Global South and contributes to greater stability and confidence in the global multilateral trading system.
基金supported by the Major Project of the National Social Science Fund of China,titled“Design Path Selection for the Mechanism of New and Old Growth Driver Conversion”(Grant No.18ZDA077)by the Joint Special Major Research Project of the Yangtze River Delta Economics and Social Development Research Center at Nanjing University and the Collaborative Innovation Center for China Economy(CICCE),titled“Practicing Innovation in China’s Development Economics for the Yangtze River Delta:From Industrial Clusters to Technological Clusters”(Grant No.CYD2022006).
文摘The global clustering of inventive talent shapes innovation capacity and drives economic growth.For China,this process is especially crucial in sustaining its development momentum.This paper draws on data from the EPO Worldwide Patent Statistical Database(PATSTAT)to extract global inventive talent mobility information and analyzes the spatial structural evolution of the global inventive talent flow network.The study finds that this network is undergoing a multi-polar transformation,characterized by the rising importance of a few central countries-such as the United States,Germany,and China-and the increasing marginalization of many peripheral countries.In response to this typical phenomenon,the paper constructs an endogenous migration model and conducts empirical testing using the Temporal Exponential Random Graph Model(TERGM).The results reveal several endogenous mechanisms driving global inventive talent flows,including reciprocity,path dependence,convergence effects,transitivity,and cyclic structures,all of which contribute to the network’s multi-polar trend.In addition,differences in regional industrial structures significantly influence talent mobility choices and are a decisive factor in the formation of poles within the multi-polar landscape.Based on these findings,it is suggested that efforts be made to foster two-way channels for talent exchange between China and other global innovation hubs,in order to enhance international collaboration and knowledge flow.We should aim to reduce the migration costs and institutional barriers faced by R&D personnel,thereby encouraging greater mobility of high-skilled talent.Furthermore,the government is advised to strategically leverage regional strengths in high-tech industries as a lever to capture competitive advantages in emerging technologies and products,ultimately strengthening the country’s position in the global innovation landscape.
基金Project supported by the National Natural Science Foundation of China （Grant No 10204017） and the Natural Science of Jiangsu Province, China （Grant No BK2002038）.
文摘Nanofluids or liquids with suspended nanoparticles are likely to be the future heat transfer media, as they exhibit higher thermal conductivity than those of liquids. It has been proposed that nanoparticles are apt to congregate and form clusters, and hence the interaction between nanoparticles becomes important. In this paper, by taking into account the interaction between nearest-neighbour inclusions, we adopt the multiple image method to investigate the effective thermal conductivity of nanofluids. Numerical results show that then the thermal conductivity ratio between the nanoparticles and fluids is large, and the two nanoparticles are close up and even touch, and the polnt-dipole theory such as Maxwell-Garnett theory becomes rough as many-body interactions are neglected. Our theoretical results on the effective thermal conductivity of CuO/water and Al2O3/water nanofluids are in good agreement with experimental data.
文摘A sputtering-type microwave multipolar ECR plasma processing for preparing thin films, is built with Nd-Fe-B magnets and 2.45 GHz, TE<sub>10</sub> mode microwave. The plasma distributions in the axial direction, which is important for preparing thin films, are found to be very sensitive to the magnetic potential fields in plasma chamber. The plasma parameters are also influenced by the background gas pressure.
基金National Natural Science Foundation of China(No.61671414)Natural Science Foundation for Young Scientists of Shanxi Province,China(No.201601D202035)
文摘The acoustic focusing effect of metamaterial has a wide range of applications in medicine,acoustic imaging,signal detection,etc.This paper presents an acoustic metamaterial applied to the acoustic focusing effect.The formation of acousticmetamaterial is designed into a cylindrical structure with three layers of ludox,cork and fluid rubber,which can produce a focusingphenomenon when acoustic waves propagate in air.For these strange phenomena,a scientific description is given theorietically.It can also be concluded that when the frequency of the incident acoustic wave increases?the number of peripheral bandsoutside the focusing poles will increase periodically.Besides,there are numerous groups of multipolar focusing phenomena inhigh frequency.The design of this acoustic metamaterial is successful through theorietical and experimental verification,therefore,it can be applied to acoustic communication and test.
基金National Natural Science Foundation of China(No.61671414)Natural Science Foundation for Young Scientists of Shanxi Province,China(No.201601D202035)
文摘Research of the acoustic local effect of metamaterial is widely used in the fields of environmental science,military industry and biomedicine.In this paper,the metamaterial is designed by annular columnar structures.The acoustic local effect in slender columnar structure with two layers of rings in air is investigated.Results prove that when the plane acoustic wave is incident into the model,complex interference and diffraction occur.And at different frequencies,multipolar acoustic local effect existes and cycle distribution phenomenon is observed.It is noteworthy that this phenomenon has very weak relatedness with the materials and acoustic parameters of the model.The research of this metamaterial design in this paper has definite reference significance in the acoustic communication and amplification of the acoustic signal detection.
基金Supported by National Natural Science Foundation of China under Grant No.11575066Domestic ITER under Grant No.2009GB105003
文摘The multipolar velocity field structures are investigated by 2D momentum conservation equation with 3D equilibrium sheared flows in the full toroidal system. Numerical results show that the non-existence of radial velocity field in equilibrium surfaces is suitable only for the zero-order term of our 2D simulation. The non-zero-order radial velocity field is still preserved, even when converted to conventional magnetic surface coordinates. The distribution of velocity field vectors of the order of 1, 2, and 3 are presented respectively in 2, 4, and 6 polar fields with the local vortex structure. The excitation mechanisms of these velocity vortices are the coupling effects of the magneto-fluid structure patterns and the toroidal effects. These results can help us understand the complexity of core physics, the transverse transport across magnetic field by the radial plasma flow and the formation of velocity vortices.
文摘The multipolar magnetic field structure is investigated by the momentum conservation equation with self-c on sistent 3D sheared flows during transition of plasma properties from local paramagnetic to diamagnelic fields.Numerical results show that the traditional poloidal magnetic field(Bp)is one part of equilibrium magnetic fields.The non-zero-order quantities are originaled from the higher-order terms of 2D equilibrium treatment based on a Fourier expansion of 0(r,0).The distributions of magnetic field vectors of the order of 1,2,and 3 terms are presented respectively in two.four,and six polar fields with the local vortex structures(spontaneous magnetic conn ection).The excitation mechanisms of the magnetic vortices are the coupling effects of the magnetic fluid structure pattern and the toroidal effects.These results can help us understand the physical mechanism of the in teraction between the external perturbation fields and control tearing modes,as well as the radial plasma flow and magnetic vortices.
基金Project supported by the National Natural Science Foundation of China （Grant No 10474089）.
文摘The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence-shell excitations in 4d, 4f, 5p, 5d, 6s, 6p, 7s ←4p of krypton atom have been determined. Their profiles are discussed, and the generalized oscillator strengths for the electric monopole and quadrupole excitations in 5p ← 4p are compared with the calculations of Amusia et al. （Phys. Rev. A 67 022703 （2003））. The differences between the experimental results and theoretical calculations show that more studies are needed.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0304402)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grants No.XDB21030300)the Hubei Province Science Fund for Distinguished Young Scholars,China(Grant No.2019CFA058).
文摘The pursuit of a systematic frequency uncertainty beyond 10^(-18) clock has triggered a multitude of investigations on the multipolar and higher-order lattice light shifts.The Cd atom has been proposed as a new candidate for the development of a lattice clock because of its smaller blackbody radiation shift at room temperature.Here,we apply an improved combined method of the Dirac-Fock plus core polarization and relativistic configuration interaction methods to calculate the dynamic multipolar polarizabilities of the Cd clock states.The effects of the high-order core-polarization potentials on the energies,reduced matrix elements,and multipolar polarizabilities have been evaluated systematically.The detailed comparison with available literature demonstrates that taking into account of the high-order core-polarization potentials is a simple and effective approach to improve the results of atomic properties for heavy atoms.
基金supported by the Major State Basic Research Development Program of China （973 program, No. 2009GB103000）, National Natural Science Foundation of China （No. 10835009）, and the Chinese Academy of Sciences with grant ID of KJCX3.SYW.N4
文摘A new method for plasma boundary reconstruction, based on the toroidal multipolar expansion （TME） scheme, is applied successfully in EAST. TME applies a limited number of toroidal multipolar moments based on toroidal coordinates to treat a two-dimensional problem of axisymmetric plasma equilibrium. The plasma boundary reconstructed by TME is consistent with the results by using EFIT. The method is sufficiently reliable and fast for real time shape control.
文摘Purpose: Pulmonary vein isolation (PVI) is the accepted primary endpoint for catheter ablation of atrial fibrillation (AF). The aim of this study was to evaluate the level of PVI by PVAC, a multipolar circular catheter utilizing bipolar/unipolar radiofrequency (RF) energy. Methods: Twenty patients with paroxysmal AF underwent PVAC ablation. PVI was validated by voltage reduction and pacing tests. Before and after RF ablation, left atrium (LA) and PV electroanatomic mapping (EAM) were performed by EnSite NavX system. Voltage abatement was considered for potentials 24mm: 9/20 (45%) vs 11/57 (19%),
文摘The words that Xi Jinping said at the 47th World Economic Forum(WEF)have really surprised just the most inattentive people.During his visit to Davos,where leaders,entrepreneurs
文摘At present,changes of great consequence for our world are unfolding in unprecedented ways.These changes present both strategic opportunities and serious challenges.Confronting the critical global issues facing the world today,such as the deficits in peace,development,security,and governance.
基金National Natural Science Foundation of China(62375158,62105187)Natural Science Foundation of Shandong Province(ZR2021QF010,ZR2020MF107)Development Plan of Youth Innovation Team in Colleges and Universities of Shandong Province(2022KJ216)。
文摘Spatiotemporal optical vortices(STOVs)exhibit characteristics of transverse orbital angular momentum(OAM)that is perpendicular to the direction of pulse propagation,indicating significant potential for diverse applications.In this study,we employ vanadium dioxide and photonic crystal plates to design tunable transreflective dual-channel terahertz(THz)spatiotemporal vortex generation devices that possess multipolarization adaptability.In the reflection channel,we achieve active tunability of the topological dark lines by utilizing circularly polarized light,based on the topological dark phenomenon,and observe variations in the number of singularities across the parameter space from different observational perspectives.In the transmission channel,we generate independent vortex singularities using linearly polarized light.This multifunctional terahertz device offers a novel approach for the generation and active tuning of spatiotemporal vortices.
文摘China and India mark 75 years of diplomatic ties,reflecting on past challenges and achievements while focusing on stabilization,cooperation and shaping a multipolar global future.
文摘This analysis explores China's quest for international legitimacy through its leadership in the BRICS+expansion,a strategic maneuver to foster a multipolar world that integrates diverse political and economic systems.The evolution into BRICS+is significant,with the collective GDP of member countries reaching $30.76 trillion,accounting for 30% of the global economy.This underscores the alliance's economic impact and challenges the existing world order.The inclusion of nations like Saudi Arabia,Iran,Ethiopia,Egypt,and the UAE offers a blueprint for shared benefits and mutual growth.China advocates for an alternative,inclusive pathway to legitimacy,promoting a world order that values sovereignty,cultural identity,and balanced global governance.
