Needleless electrospinning is a versatile method to produce nanofibers.In particular,the rotary version of this technique has enjoyed widespread use because there is no need to clean the spinneret.The rotation speed i...Needleless electrospinning is a versatile method to produce nanofibers.In particular,the rotary version of this technique has enjoyed widespread use because there is no need to clean the spinneret.The rotation speed is limited by the potential deviation of the jet due to the centrifugal force.Other limitations are due to the fast volatilization of the solvent from the opened spinning system.In order to overcome these drawbacks,here a novel reciprocating system based on a moving spinning-plate is proposed.The spinning process is implemented in a half-closed system with the spinning-plate immersed in the solution tank.When the immersed spinning-plate moves up from the solution tank,multiple jets are ejected from the droplets on the tips of the spinning-plate under the effect of an electric field force.The morphology of the obtained nanofibers has been analyzed by scanning electron microscopy.The results indicated that the obtained fibers are uniform in structures and small in diameters.Both issues of needle clogging and intense solvent evaporation can be mitigated using this alternate approach.展开更多
The dynamical equations for a inertial reciprocating machine excited by two rotating eccentric weights were built by the matrix methodology for establishing dynamical equations of discrete systems. A mathematical mode...The dynamical equations for a inertial reciprocating machine excited by two rotating eccentric weights were built by the matrix methodology for establishing dynamical equations of discrete systems. A mathematical model of electromechanical coupling system for the machine was formed by combining the dynamical equations with the state equations of the two motors. The computer simulation to the model was performed for several values of the damping coefficient or the motor power, respectively. The substance of transient behavior of the machine is unveiled by analyzing the results of the computer simulation, and new methods are presented for diminishing the transient amplitude of the vibrating machine and improving the transient behavior. The reliable mathematical model is provided for intelligent control of the transient behavior and engineering design of the equipment.展开更多
The governing equation, together with the formulas of the averaged flux and the stability parameter for Newtonian fluid flowing in eccentric annulus via the axial reciprocation of the inner tube was established in the...The governing equation, together with the formulas of the averaged flux and the stability parameter for Newtonian fluid flowing in eccentric annulus via the axial reciprocation of the inner tube was established in the bipolar coordinate system. Numerical calculation was conducted for the measurement of water flow using the formulas above, of which the results agree well with the experimental data. It is shown that the flow instability can be induced by the increase of the stroke, the frequency, and the eccentricity of annulus, making the sucker rod more susceptible to partial abrasion. Some protecting methods, including adding centralizers, adjusting the stroke and frequency, are proposed to protect the sucker rod from the partial abrasion, and satisfactory results have been achieved in the oilfields.展开更多
Nonreciprocal optical devices are essential for laser protection,modern optical communication and quantum information processing by enforcing one-way light propagation.The conventional Faraday magneto-optical nonrecip...Nonreciprocal optical devices are essential for laser protection,modern optical communication and quantum information processing by enforcing one-way light propagation.The conventional Faraday magneto-optical nonreciprocal devices rely on a strong magnetic field,which is provided by a permanent magnet.As a result,the isolation direction of such devices is fixed and severely restricts their applications in quantum networks.In this work,we experimentally demonstrate the simultaneous one-way transmission and unidirectional reflection by using a magneto-optical Fabry-Pérot cavity and a magnetic field strength of 50 mT.An optical isolator and a three-port quasi-circulator are realized based on this nonreciprocal cavity system.The isolator achieves an isolation ratio of up to 22 dB and an averaged insertion loss down to 0.97 dB.The quasi-circulator is realized with a fidelity exceeding 99% and an overall survival probability of 89.9%,corresponding to an insertion loss of~0.46 dB.The magnetic field is provided by an electromagnetic coil,thereby allowing for reversing the light circulating path.The reversible quasi-circulator paves the way for building reconfigurable quantum networks.展开更多
Controlling the size and distribution of potential barriers within a medium of interacting particles can unveil unique collective behaviors and innovative functionalities.We introduce a unique superconducting hybrid d...Controlling the size and distribution of potential barriers within a medium of interacting particles can unveil unique collective behaviors and innovative functionalities.We introduce a unique superconducting hybrid device using a novel artificial spin ice structure composed of asymmetric nanomagnets.This structure forms a distinctive superconducting pinning potential that steers unconventional motion of superconducting vortices,thereby inducing a magnetic nonreciprocal effect,in contrast to the electric nonreciprocal effect commonly observed in superconducting diodes.Furthermore,the polarity of the magnetic nonreciprocity is in situ reversible through the tunable magnetic patterns of artificial spin ice.Our findings demonstrate that artificial spin ice not only precisely modulates superconducting characteristics but also opens the door to novel functionalities,offering a groundbreaking paradigm for superconducting electronics.展开更多
This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying delays.By i...This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying delays.By introducing two adjustable parameters and two free variables,a novel convex function greater than or equal to the quadratic function is constructed,regardless of the sign of the coefficient in the quadratic term.The developed lemma can also be degenerated into the existing quadratic function negative-determination(QFND)lemma and relaxed QFND lemma respectively,by setting two adjustable parameters and two free variables as some particular values.Moreover,for a linear system with time-varying delays,a relaxed stability criterion is established via our developed lemma,together with the quivalent reciprocal combination technique and the Bessel-Legendre inequality.As a result,the conservatism can be reduced via the proposed approach in the context of constructing Lyapunov-Krasovskii functionals for the stability analysis of linear time-varying delay systems.Finally,the superiority of our results is illustrated through three numerical examples.展开更多
We compare Newton’s force law of universal gravitation with a corrected simple approach based on Bhandari’s recently presented work, where the gravitation constant G is maintained. A reciprocity relation exists betw...We compare Newton’s force law of universal gravitation with a corrected simple approach based on Bhandari’s recently presented work, where the gravitation constant G is maintained. A reciprocity relation exists between both alternative gravity formulas with respect to the distances between mass centers. We conclude a one-to-one mapping of the two gravitational formulas. We don’t need Einstein’s construct of spacetime bending by matter.展开更多
Dear Editor,This letter examines the stability issue of generalized neural networks(GNNs) with time-varying delay based on a novel reciprocally convex combination(RCC). By considering a new matrix polynomial, the prop...Dear Editor,This letter examines the stability issue of generalized neural networks(GNNs) with time-varying delay based on a novel reciprocally convex combination(RCC). By considering a new matrix polynomial, the proposed novel reciprocally convex method leads to a tight bound for integral inequality combination and encompasses several existing approaches as special cases.展开更多
Variation in patterns of recombination in plant genomes provides information about species evolution,genetic diversity and crop improvement. We investigated meiotic crossovers generated in biparental segregating and r...Variation in patterns of recombination in plant genomes provides information about species evolution,genetic diversity and crop improvement. We investigated meiotic crossovers generated in biparental segregating and reciprocal backcross populations of the allopolyploid genome of rapeseed(Brassica napus)(AACC, 2n = 38). A structured set of 1445 intercrossed lines was derived from two homozygous de novo genome-assembled parents that represented the major genetic clusters of semi-winter Chinese and winter European rapeseeds, and was used to increase QTL resolution and achieve genomic reciprocal introgression. A high-density genetic map constructed with 6161 genetic bins and anchored centromere regions was used to establish the pattern of recombination variation in each chromosome. Around 93%of the genome contained crossovers at a mean rate of 3.8 c M Mb^(-1), with the remaining 7% attributed to centromeres or low marker density. Recombination hotspots predominated in the A genome, including two-thirds of those associated with breeding introgression from B. rapa. Genetic background might affect recombination variation. Introgression of genetic diversity from European winter to Chinese semi-winter rapeseed showed an increase in crossover rate under the semi-winter environment. Evidence for an elevated recombination rate having historically contributed to selective trait improvement includes accumulation of favorable alleles for seed oil content on hotspots of chromosome A10. Conversely, strong artificial selection may affect recombination rate variation, as appears to be the case with a coldspot resulting from strong selection for glucosinolate alleles on A09. But the cold region would be promptly reactivated by crossing design indicated by the pedigree analysis. Knowledge of recombination hotspots and coldspots associated with QTL for 22 traits can guide selection strategies for introgression breeding between the two gene pools. These results and rich genomic resources broaden our understanding of recombination behavior in allopolyploids and may advance rapeseed genetic improvement.展开更多
Phonon lasers,as a novel kind of lasers for generating coherent sound oscillation,has attracted extensive attention.Here,we theoretically propose a nonreciprocal phonon laser in a hybrid optomechanical system,which is...Phonon lasers,as a novel kind of lasers for generating coherent sound oscillation,has attracted extensive attention.Here,we theoretically propose a nonreciprocal phonon laser in a hybrid optomechanical system,which is composed of an asymmetric Fabry-Pérot cavity,an ensemble of N identical two-level atoms,and a mechanical oscillator.The effective driving amplitude related to driving direction leads to an obvious difference in mechanical gain and threshold power,bringing about a nonreciprocal phonon laser.In addition,the dependence of the phonon laser on the atomic parameters is also discussed,including the decay rate of the atoms and the coupling strength between the atoms and the cavity field,which provides an additional degree of freedom to control the phonon laser action.Our work provides a path to realizing a phonon laser in an atoms-cavity optomechanical system and may aid the manufacture of directional coherent phonon sources.展开更多
Nonreciprocal effects are consistently observed in noncentrosymmetric materials due to the intrinsic symmetry breaking and in high-conductivity systems due to the extrinsic thermoelectric effect. Meanwhile, nonrecipro...Nonreciprocal effects are consistently observed in noncentrosymmetric materials due to the intrinsic symmetry breaking and in high-conductivity systems due to the extrinsic thermoelectric effect. Meanwhile, nonreciprocal charge transport is widely utilized as an effective experimental technique for detecting intrinsic unidirectional electrical contributions. Here, we show an unconventional nonreciprocal voltage transition in topological insulator Ag_(2)Te nanobelts. The nonreciprocal voltage develops from nearly zero to giant values under the applied current I_(ac) and external magnetic fields, while remaining unchanged under various current I_(dc). This unidirectional electrical contribution is further evidenced by the differential resistance(dV/dI) measurements. Furthermore, the transition possesses two-dimensional properties under a tilted magnetic field and occurs when the voltage between two electrodes exceeds a certain value. We propose a possible mechanism based on the development of edge channels in Ag_(2)Te nanobelts to interpret the phenomenon. Our results not only introduce a peculiar nonreciprocal voltage transition in topological materials but also enrich the understanding of the intrinsic mechanism that strongly affects nonreciprocal charge transport.展开更多
Inspired by the problem of biofilm growth,we numerically investigate clustering in a two-dimensional suspension of active(Janus)particles of finite size confined in a circular cavity.Their dynamics is regulated by a n...Inspired by the problem of biofilm growth,we numerically investigate clustering in a two-dimensional suspension of active(Janus)particles of finite size confined in a circular cavity.Their dynamics is regulated by a non-reciprocal mechanism that causes them to switch from active to passive above a certain threshold of the perceived near-neighbor density(quorum sensing).A variety of cluster phases,i.e.,glassy,solid(hexatic)and liquid,are observed,depending on the particle dynamics at the boundary,the quorum sensing range,and the level of noise.展开更多
Recent studies have identified plasma as a topological material.Yet,these researches often depict plasma as a fluid governed by electromagnetic fields,i.e.,a classical wave system.Indeed,plasma transport can be charac...Recent studies have identified plasma as a topological material.Yet,these researches often depict plasma as a fluid governed by electromagnetic fields,i.e.,a classical wave system.Indeed,plasma transport can be characterized by a unique diffusion process distinguished by its collective behaviors.We adopt a simplified diffusion-migration method to elucidate the topological plasma transport.Drawing parallels to the thermal conduction-convection system,we introduce a double-ring model to investigate the plasma density behaviors in the anti-parity-time reversal(APT) unbroken and broken phases.Subsequently,by augmenting the number of rings,we have established a coupled ring chain structure.This structure serves as a medium for realizing the APT symmetric one-dimensional(1D) reciprocal model,representing the simplest tight-binding model with a trivial topology.To develop a model featuring topological properties,we should modify the APT symmetric 1D reciprocal model from the following two aspects:hopping amplitude and onsite potential.From the hopping amplitude,we incorporate the non-reciprocity to facilitate the non-Hermitian skin effect,an intrinsic non-Hermitian topology.Meanwhile,from the onsite potential,the quasiperiodic modulation has been adopted onto the APT symmetric 1D reciprocal model.This APT symmetric 1D Aubry–André–Harper model is of topological nature.Additionally,we suggest the potential applications for these diffusive plasma topological states.This study establishes a diffusion-based approach to realize topological states in plasma,potentially inspiring further advancements in plasma physics.展开更多
Beam splitters play a crucial role in a wide range of optical systems.A typical beam splitter consists of several transport channels,and an input beam from one channel is split into multiple output beams coupled into ...Beam splitters play a crucial role in a wide range of optical systems.A typical beam splitter consists of several transport channels,and an input beam from one channel is split into multiple output beams coupled into other channels.For traditional beam splitters,their transportation channels(either in free space or waveguides)are reciprocal,being sensitive to various perturbations caused by defects and obstacles.展开更多
This paper first attempts to solve the transient heat conduction problem by combining the recently proposed local knot method(LKM)with the dual reciprocity method(DRM).Firstly,the temporal derivative is discretized by...This paper first attempts to solve the transient heat conduction problem by combining the recently proposed local knot method(LKM)with the dual reciprocity method(DRM).Firstly,the temporal derivative is discretized by a finite difference scheme,and thus the governing equation of transient heat transfer is transformed into a non-homogeneous modified Helmholtz equation.Secondly,the solution of the non-homogeneous modified Helmholtz equation is decomposed into a particular solution and a homogeneous solution.And then,the DRM and LKM are used to solve the particular solution of the non-homogeneous equation and the homogeneous solution of the modified Helmholtz equation,respectively.The LKM is a recently proposed local radial basis function collocationmethod with themerits of being simple,accurate,and free ofmesh and integration.Compared with the traditional domain-type and boundary-type schemes,the present coupling algorithm could be treated as a really good alternative for the analysis of transient heat conduction on high-dimensional and complicated domains.Numerical experiments,including two-and three-dimensional heat transfer models,demonstrated the effectiveness and accuracy of the new methodology.展开更多
Promoting the co-constructing and sharing of organizational knowledge and improving organizational performance have always been the core research subject of knowledge management.Existing research focuses on the constr...Promoting the co-constructing and sharing of organizational knowledge and improving organizational performance have always been the core research subject of knowledge management.Existing research focuses on the construction of knowledge management systems and knowledge sharing and transfer mechanisms.With the rapid development and application of cloud computing and big data technology,knowledge management is faced with many problems,such as how to combine with the new generation of information technology,how to achieve integration with organizational business processes,and so on.To solve such problems,this paper proposes a reciprocal collaborative knowledge management model(RCKMmodel)based on cloud computing technology,reciprocity theory,and collaboration technology.RCKM model includes project group management and cloud computing technology,which can realize management,finance,communication,and quality assurance of multiple projects and solve the problem of business integration with knowledge management.This paper designs evaluation methods of tacit knowledge and reciprocity preference based on the Bayesian formula and analyzes their effect with simulation data.The methods can provide quantitative support for the integration of knowledge management and business management to realize reciprocity and collaboration in the RCKM model.The research found that RCKM model can fully use cloud computing technology to promote the integration of knowledge management and organizational business,and the evaluation method based on the Bayesian formula can provide relatively accurate data support for the evaluation and selection of project team members.展开更多
基金The work is supported by Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),National Natural Science Foundation of China under Grant No.11372205.
文摘Needleless electrospinning is a versatile method to produce nanofibers.In particular,the rotary version of this technique has enjoyed widespread use because there is no need to clean the spinneret.The rotation speed is limited by the potential deviation of the jet due to the centrifugal force.Other limitations are due to the fast volatilization of the solvent from the opened spinning system.In order to overcome these drawbacks,here a novel reciprocating system based on a moving spinning-plate is proposed.The spinning process is implemented in a half-closed system with the spinning-plate immersed in the solution tank.When the immersed spinning-plate moves up from the solution tank,multiple jets are ejected from the droplets on the tips of the spinning-plate under the effect of an electric field force.The morphology of the obtained nanofibers has been analyzed by scanning electron microscopy.The results indicated that the obtained fibers are uniform in structures and small in diameters.Both issues of needle clogging and intense solvent evaporation can be mitigated using this alternate approach.
文摘The dynamical equations for a inertial reciprocating machine excited by two rotating eccentric weights were built by the matrix methodology for establishing dynamical equations of discrete systems. A mathematical model of electromechanical coupling system for the machine was formed by combining the dynamical equations with the state equations of the two motors. The computer simulation to the model was performed for several values of the damping coefficient or the motor power, respectively. The substance of transient behavior of the machine is unveiled by analyzing the results of the computer simulation, and new methods are presented for diminishing the transient amplitude of the vibrating machine and improving the transient behavior. The reliable mathematical model is provided for intelligent control of the transient behavior and engineering design of the equipment.
基金the National Natural Science Foundation of China (Grand No. 50674019)the Natural Science Foundation of Heilongjiang Province (Grant No. A200501).
文摘The governing equation, together with the formulas of the averaged flux and the stability parameter for Newtonian fluid flowing in eccentric annulus via the axial reciprocation of the inner tube was established in the bipolar coordinate system. Numerical calculation was conducted for the measurement of water flow using the formulas above, of which the results agree well with the experimental data. It is shown that the flow instability can be induced by the increase of the stroke, the frequency, and the eccentricity of annulus, making the sucker rod more susceptible to partial abrasion. Some protecting methods, including adding centralizers, adjusting the stroke and frequency, are proposed to protect the sucker rod from the partial abrasion, and satisfactory results have been achieved in the oilfields.
基金supported by the National Key R&D Program of China(Grant No.2019YFA0308700)the National Natural Science Foundation of China(Grant Nos.11890704,92365107,and 12305020)+2 种基金the Program for Innovative Talents and Teams in Jiangsu(Grant No.JSSCTD202138)the Shccig-Qinling Program,the China Postdoctoral Science Foundation(Grant No.2023M731613)the Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2023ZB708)。
文摘Nonreciprocal optical devices are essential for laser protection,modern optical communication and quantum information processing by enforcing one-way light propagation.The conventional Faraday magneto-optical nonreciprocal devices rely on a strong magnetic field,which is provided by a permanent magnet.As a result,the isolation direction of such devices is fixed and severely restricts their applications in quantum networks.In this work,we experimentally demonstrate the simultaneous one-way transmission and unidirectional reflection by using a magneto-optical Fabry-Pérot cavity and a magnetic field strength of 50 mT.An optical isolator and a three-port quasi-circulator are realized based on this nonreciprocal cavity system.The isolator achieves an isolation ratio of up to 22 dB and an averaged insertion loss down to 0.97 dB.The quasi-circulator is realized with a fidelity exceeding 99% and an overall survival probability of 89.9%,corresponding to an insertion loss of~0.46 dB.The magnetic field is provided by an electromagnetic coil,thereby allowing for reversing the light circulating path.The reversible quasi-circulator paves the way for building reconfigurable quantum networks.
基金supported by the National Natural Science Foundation of China(Grant Nos.62288101 and 62274086)the National Key R&D Program of China(Grant No.2021YFA0718802)the Jiangsu Outstanding Postdoctoral Program。
文摘Controlling the size and distribution of potential barriers within a medium of interacting particles can unveil unique collective behaviors and innovative functionalities.We introduce a unique superconducting hybrid device using a novel artificial spin ice structure composed of asymmetric nanomagnets.This structure forms a distinctive superconducting pinning potential that steers unconventional motion of superconducting vortices,thereby inducing a magnetic nonreciprocal effect,in contrast to the electric nonreciprocal effect commonly observed in superconducting diodes.Furthermore,the polarity of the magnetic nonreciprocity is in situ reversible through the tunable magnetic patterns of artificial spin ice.Our findings demonstrate that artificial spin ice not only precisely modulates superconducting characteristics but also opens the door to novel functionalities,offering a groundbreaking paradigm for superconducting electronics.
基金the National Natural Science Foundation of China(62273058,U22A2045)the Key Science and Technology Projects of Jilin Province(20200401075GX)the Youth Science and Technology Innovation and Entrepreneurship Outstanding Talents Project of Jilin Province(20230508043RC)。
文摘This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying delays.By introducing two adjustable parameters and two free variables,a novel convex function greater than or equal to the quadratic function is constructed,regardless of the sign of the coefficient in the quadratic term.The developed lemma can also be degenerated into the existing quadratic function negative-determination(QFND)lemma and relaxed QFND lemma respectively,by setting two adjustable parameters and two free variables as some particular values.Moreover,for a linear system with time-varying delays,a relaxed stability criterion is established via our developed lemma,together with the quivalent reciprocal combination technique and the Bessel-Legendre inequality.As a result,the conservatism can be reduced via the proposed approach in the context of constructing Lyapunov-Krasovskii functionals for the stability analysis of linear time-varying delay systems.Finally,the superiority of our results is illustrated through three numerical examples.
文摘We compare Newton’s force law of universal gravitation with a corrected simple approach based on Bhandari’s recently presented work, where the gravitation constant G is maintained. A reciprocity relation exists between both alternative gravity formulas with respect to the distances between mass centers. We conclude a one-to-one mapping of the two gravitational formulas. We don’t need Einstein’s construct of spacetime bending by matter.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,Information and Communications Technology(ICT),and Future Planning(2020 R1A2C2005709)the National Natural Science Foundation of China(618255304)the Key Project of Natural Science Foundation of Hebei Province(F2021203054)。
文摘Dear Editor,This letter examines the stability issue of generalized neural networks(GNNs) with time-varying delay based on a novel reciprocally convex combination(RCC). By considering a new matrix polynomial, the proposed novel reciprocally convex method leads to a tight bound for integral inequality combination and encompasses several existing approaches as special cases.
基金supported by the National Key Research and Development Program of China (2021YFF1000100)the National Natural Science Foundation of China (31970564 and 32171982)the National Key Research and Development Program of China (2016YFD0100305)。
文摘Variation in patterns of recombination in plant genomes provides information about species evolution,genetic diversity and crop improvement. We investigated meiotic crossovers generated in biparental segregating and reciprocal backcross populations of the allopolyploid genome of rapeseed(Brassica napus)(AACC, 2n = 38). A structured set of 1445 intercrossed lines was derived from two homozygous de novo genome-assembled parents that represented the major genetic clusters of semi-winter Chinese and winter European rapeseeds, and was used to increase QTL resolution and achieve genomic reciprocal introgression. A high-density genetic map constructed with 6161 genetic bins and anchored centromere regions was used to establish the pattern of recombination variation in each chromosome. Around 93%of the genome contained crossovers at a mean rate of 3.8 c M Mb^(-1), with the remaining 7% attributed to centromeres or low marker density. Recombination hotspots predominated in the A genome, including two-thirds of those associated with breeding introgression from B. rapa. Genetic background might affect recombination variation. Introgression of genetic diversity from European winter to Chinese semi-winter rapeseed showed an increase in crossover rate under the semi-winter environment. Evidence for an elevated recombination rate having historically contributed to selective trait improvement includes accumulation of favorable alleles for seed oil content on hotspots of chromosome A10. Conversely, strong artificial selection may affect recombination rate variation, as appears to be the case with a coldspot resulting from strong selection for glucosinolate alleles on A09. But the cold region would be promptly reactivated by crossing design indicated by the pedigree analysis. Knowledge of recombination hotspots and coldspots associated with QTL for 22 traits can guide selection strategies for introgression breeding between the two gene pools. These results and rich genomic resources broaden our understanding of recombination behavior in allopolyploids and may advance rapeseed genetic improvement.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA1400700)the National Natural Science Foundation of China(Grant Nos.11774113and 12022507)the Fundamental Research Funds for the Central Universities(Grant No.2019kfy RCPY111)。
文摘Phonon lasers,as a novel kind of lasers for generating coherent sound oscillation,has attracted extensive attention.Here,we theoretically propose a nonreciprocal phonon laser in a hybrid optomechanical system,which is composed of an asymmetric Fabry-Pérot cavity,an ensemble of N identical two-level atoms,and a mechanical oscillator.The effective driving amplitude related to driving direction leads to an obvious difference in mechanical gain and threshold power,bringing about a nonreciprocal phonon laser.In addition,the dependence of the phonon laser on the atomic parameters is also discussed,including the decay rate of the atoms and the coupling strength between the atoms and the cavity field,which provides an additional degree of freedom to control the phonon laser action.Our work provides a path to realizing a phonon laser in an atoms-cavity optomechanical system and may aid the manufacture of directional coherent phonon sources.
基金supported by the National Natural Science Foundation of China (Grant Nos. 52225207, 11934005, and 52350001)the Shanghai Pilot Program for Basic Research-FuDan University21TQ1400100 (Grant No. 21TQ006)the Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01)。
文摘Nonreciprocal effects are consistently observed in noncentrosymmetric materials due to the intrinsic symmetry breaking and in high-conductivity systems due to the extrinsic thermoelectric effect. Meanwhile, nonreciprocal charge transport is widely utilized as an effective experimental technique for detecting intrinsic unidirectional electrical contributions. Here, we show an unconventional nonreciprocal voltage transition in topological insulator Ag_(2)Te nanobelts. The nonreciprocal voltage develops from nearly zero to giant values under the applied current I_(ac) and external magnetic fields, while remaining unchanged under various current I_(dc). This unidirectional electrical contribution is further evidenced by the differential resistance(dV/dI) measurements. Furthermore, the transition possesses two-dimensional properties under a tilted magnetic field and occurs when the voltage between two electrodes exceeds a certain value. We propose a possible mechanism based on the development of edge channels in Ag_(2)Te nanobelts to interpret the phenomenon. Our results not only introduce a peculiar nonreciprocal voltage transition in topological materials but also enrich the understanding of the intrinsic mechanism that strongly affects nonreciprocal charge transport.
基金supported by the National Natural Science Foundation of China(Grant Nos.12375037 and 11935010)。
文摘Inspired by the problem of biofilm growth,we numerically investigate clustering in a two-dimensional suspension of active(Janus)particles of finite size confined in a circular cavity.Their dynamics is regulated by a non-reciprocal mechanism that causes them to switch from active to passive above a certain threshold of the perceived near-neighbor density(quorum sensing).A variety of cluster phases,i.e.,glassy,solid(hexatic)and liquid,are observed,depending on the particle dynamics at the boundary,the quorum sensing range,and the level of noise.
基金supported by the National Natural Science Foundation of China(Grant Nos.12035004 and 12320101004)the Science and Technology Commission of Shanghai Municipality(Grant No.20JC1414700)the Innovation Program of Shanghai Municipal Education Commission(Grant No.2023ZKZD06)。
文摘Recent studies have identified plasma as a topological material.Yet,these researches often depict plasma as a fluid governed by electromagnetic fields,i.e.,a classical wave system.Indeed,plasma transport can be characterized by a unique diffusion process distinguished by its collective behaviors.We adopt a simplified diffusion-migration method to elucidate the topological plasma transport.Drawing parallels to the thermal conduction-convection system,we introduce a double-ring model to investigate the plasma density behaviors in the anti-parity-time reversal(APT) unbroken and broken phases.Subsequently,by augmenting the number of rings,we have established a coupled ring chain structure.This structure serves as a medium for realizing the APT symmetric one-dimensional(1D) reciprocal model,representing the simplest tight-binding model with a trivial topology.To develop a model featuring topological properties,we should modify the APT symmetric 1D reciprocal model from the following two aspects:hopping amplitude and onsite potential.From the hopping amplitude,we incorporate the non-reciprocity to facilitate the non-Hermitian skin effect,an intrinsic non-Hermitian topology.Meanwhile,from the onsite potential,the quasiperiodic modulation has been adopted onto the APT symmetric 1D reciprocal model.This APT symmetric 1D Aubry–André–Harper model is of topological nature.Additionally,we suggest the potential applications for these diffusive plasma topological states.This study establishes a diffusion-based approach to realize topological states in plasma,potentially inspiring further advancements in plasma physics.
文摘Beam splitters play a crucial role in a wide range of optical systems.A typical beam splitter consists of several transport channels,and an input beam from one channel is split into multiple output beams coupled into other channels.For traditional beam splitters,their transportation channels(either in free space or waveguides)are reciprocal,being sensitive to various perturbations caused by defects and obstacles.
基金supported by the NationalNatural Science Foundation of China (No.11802151)the Natural Science Foundation of Shandong Province of China (No.ZR2019BA008)the China Postdoctoral Science Foundation (No.2019M652315).
文摘This paper first attempts to solve the transient heat conduction problem by combining the recently proposed local knot method(LKM)with the dual reciprocity method(DRM).Firstly,the temporal derivative is discretized by a finite difference scheme,and thus the governing equation of transient heat transfer is transformed into a non-homogeneous modified Helmholtz equation.Secondly,the solution of the non-homogeneous modified Helmholtz equation is decomposed into a particular solution and a homogeneous solution.And then,the DRM and LKM are used to solve the particular solution of the non-homogeneous equation and the homogeneous solution of the modified Helmholtz equation,respectively.The LKM is a recently proposed local radial basis function collocationmethod with themerits of being simple,accurate,and free ofmesh and integration.Compared with the traditional domain-type and boundary-type schemes,the present coupling algorithm could be treated as a really good alternative for the analysis of transient heat conduction on high-dimensional and complicated domains.Numerical experiments,including two-and three-dimensional heat transfer models,demonstrated the effectiveness and accuracy of the new methodology.
基金supported by the research project of the Jiangsu water conservancy science and technology project (Contract Number:2021067).
文摘Promoting the co-constructing and sharing of organizational knowledge and improving organizational performance have always been the core research subject of knowledge management.Existing research focuses on the construction of knowledge management systems and knowledge sharing and transfer mechanisms.With the rapid development and application of cloud computing and big data technology,knowledge management is faced with many problems,such as how to combine with the new generation of information technology,how to achieve integration with organizational business processes,and so on.To solve such problems,this paper proposes a reciprocal collaborative knowledge management model(RCKMmodel)based on cloud computing technology,reciprocity theory,and collaboration technology.RCKM model includes project group management and cloud computing technology,which can realize management,finance,communication,and quality assurance of multiple projects and solve the problem of business integration with knowledge management.This paper designs evaluation methods of tacit knowledge and reciprocity preference based on the Bayesian formula and analyzes their effect with simulation data.The methods can provide quantitative support for the integration of knowledge management and business management to realize reciprocity and collaboration in the RCKM model.The research found that RCKM model can fully use cloud computing technology to promote the integration of knowledge management and organizational business,and the evaluation method based on the Bayesian formula can provide relatively accurate data support for the evaluation and selection of project team members.