The degradation mechanism of the all-inorganic perovskite solar cells in the ambient environment remains unclear.In this paper,water and oxygen molecule adsorptions on the all-inorganic perovskite(CsPbBr_(3))surface a...The degradation mechanism of the all-inorganic perovskite solar cells in the ambient environment remains unclear.In this paper,water and oxygen molecule adsorptions on the all-inorganic perovskite(CsPbBr_(3))surface are studied by density-functional theory calculations.In terms of the adsorption energy,the water molecules are more susceptible than the oxygen molecules to be adsorbed on the CsPbBr_(3)surface.The water molecules can be adsorbed on both the CsBr-and PbBr-terminated surfaces,but the oxygen molecules tend to be selectively adsorbed on the CsBr-terminated surface instead of the PbBr-terminated one due to the significant adsorption energy difference.While the adsorbed water molecules only contribute deep states,the oxygen molecules introduce interfacial states inside the bandgap of the perovskite,which would significantly impact the chemical and transport properties of the perovskite.Therefore,special attention should be paid to reduce the oxygen concentration in the environment during the device fabrication process so as to improve the stability and performance of the CsPbBr_(3)-based devices.展开更多
Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-...Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves.展开更多
A coupled(2+1)-dimensional variable coefficient Ginzburg-Landau equation is studied.By virtue of the modified Hirota bilinear method,the bright one-soliton solution of the equation is derived.Some phenomena of soliton...A coupled(2+1)-dimensional variable coefficient Ginzburg-Landau equation is studied.By virtue of the modified Hirota bilinear method,the bright one-soliton solution of the equation is derived.Some phenomena of soliton propagation are analyzed by setting different dispersion terms.The influences of the corresponding parameters on the solitons are also discussed.The results can enrich the soliton theory,and may be helpful in the manufacture of optical devices.展开更多
The atmosphere is an evolutionary agent essential to the shaping of a planet,while in oceanic science and daily life,liquids are commonly seen.In this paper,we investigate a generalized variable-coefficient Korteweg-d...The atmosphere is an evolutionary agent essential to the shaping of a planet,while in oceanic science and daily life,liquids are commonly seen.In this paper,we investigate a generalized variable-coefficient Korteweg-de Vriesmodified Korteweg-de Vries equation for the atmosphere,oceanic fluids and plasmas.With symbolic computation,beginning with a presumption,we work out certain scaling transformations,bilinear forms through the binary Bell polynomials and our scaling transformations,N solitons(with N being a positive integer)via the aforementioned bilinear forms and bilinear auto-Bäcklund transformations through the Hirota method with some solitons.In addition,Painlevé-type auto-Bäcklund transformations with some solitons are symbolically computed out.Respective dependences and constraints on the variable/constant coefficients are discussed,while those coefficients correspond to the quadratic-nonlinear,cubic-nonlinear,dispersive,dissipative and line-damping effects in the atmosphere,oceanic fluids and plasmas.展开更多
Owing to the high carrier mobility,two-dimensional(2D)gallium antimonite(GaSb)is a promising channel material for field-effect transistors(FETs)in the post-silicon era.We investigated the ballistic performance of the ...Owing to the high carrier mobility,two-dimensional(2D)gallium antimonite(GaSb)is a promising channel material for field-effect transistors(FETs)in the post-silicon era.We investigated the ballistic performance of the 2D GaSb metal-oxide-semiconductor FETs with a 10 nm-gate-length by the ab initio quantum transport simulation.Because of the wider bandgap and better gate-control ability,the performance of the 10-nm monolayer(ML)GaSb FETs is generally superior to the bilayer counterparts,including the three-to-four orders of magnitude larger on-current.Via hydrogenation,the delaytime and power consumption can be further enhanced with magnitude up to 35%and 57%,respectively,thanks to the expanded bandgap.The 10-nm ML GaSb FETs can almost meet the International Technology Roadmap for Semiconductors(ITRS)for high-performance demands in terms of the on-state current,intrinsic delay time,and power-delay product.展开更多
Tunneling field effect transistors(TFETs) based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low...Tunneling field effect transistors(TFETs) based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low power devices. Here,we investigate the TFETs based on two different integration types: in-plane and vertical heterostructures composed of two kinds of layered phosphorous(β-P and δ-P) by ab initio quantum transport simulations. NDR effects have been observed in both in-plane and vertical heterostructures, and the effects become significant with the highest peak-to-valley ratio(PVR)when the intrinsic region length is near zero. Compared with the in-plane TFET based on β-P and δ-P, better performance with a higher on/off current ratio of - 10-6 and a steeper subthreshold swing(SS) of - 23 mV/dec is achieved in the vertical TFET. Such differences in the NDR effects, on/off current ratio and SS are attributed to the distinct interaction nature of theβ-P and δ-P layers in the in-plane and vertical heterostructures.展开更多
A hybrid plasmonic waveguide, consisting of two dielectric nanowires symmetrically put at the opposite corner angles of a rhombic metM, is proposed and numerically analyzed by the finite-element method. Simulations sh...A hybrid plasmonic waveguide, consisting of two dielectric nanowires symmetrically put at the opposite corner angles of a rhombic metM, is proposed and numerically analyzed by the finite-element method. Simulations show that the present waveguide can achieve the millimeter propagation distance (1244 μm) and deep subwavelength mode area (5.5 × 10-3 μm2), simultaneously. Compared with the previous hybrid waveguides based on cylinder nanowires or fiat films, the rhombie corner angles enable our waveguide to achieve both longer propagation distance and smaller mode area. This is due to the enhanced coupling between the dielectric guided mode in nanowires and the surface plasmon polariton mode at rhombic surface. Furthermore, the extreme confinement near the rhombic corner angles can strengthen the light-matter interaction greatly and make the present waveguide useful in many applications, such as nonlinear photonics, high-quality nanolazers and nanophotonic waveguides.展开更多
A kind of pollution known as electromagnetic interference(EMI),which results from ubiquitous usage of various electronic communication and military radar equipment,has been receiving increasing attention recently.Howe...A kind of pollution known as electromagnetic interference(EMI),which results from ubiquitous usage of various electronic communication and military radar equipment,has been receiving increasing attention recently.However,large-area EMI shielding on transparent and/or curved surfaces,including building windows,curved glass wall,and special requirements spaces(SRSs),remains hard to achieve.In this paper,a silver nanofiber(AgNF)based flexible and transparent EMI shielding film was successfully assembled via a room-temperature roll-to-roll production method.For transparent application scenario,AgNF with 89%transmittance in visible range and 1μm thickness shows~20 dB shielding efficiency(EMI SE).On the other hand,total shielding(>50 dB)is obtained when the thickness of AgNF increases to 10μm,while its transmittance in visible range remains higher than 75%.Considering the facile and scale-free production technology,this material can be readily applied in large-scale,transparent,and/or SRSs EMI shielding.展开更多
Water waves are one of the most common phenomena in nature, the studies of which help energy development, marine/offshore engineering, hydraulic engineering, mechanical engineering, etc. Hereby, symbolic computation i...Water waves are one of the most common phenomena in nature, the studies of which help energy development, marine/offshore engineering, hydraulic engineering, mechanical engineering, etc. Hereby, symbolic computation is performed on the Boussinesq–Burgers system for shallow water waves in a lake or near an ocean beach. For the water-wave horizontal velocity and height of the water surface above the bottom, two sets of the bilinear forms through the binary Bell polynomials and N-soliton solutions are worked out, while two auto-B?cklund transformations are constructed together with the solitonic solutions, where N is a positive integer. Our bilinear forms, N-soliton solutions and B?cklund transformations are different from those in the existing literature. All of our results are dependent on the waterwave dispersive power.展开更多
In this paper, the(3+1)-dimensional generalized B-type Kadomtsev–Petviashvili equation for water waves is investigated. Through the Hirota method and Kadomtsev–Petviashvili hierarchy reduction, we obtain the first-o...In this paper, the(3+1)-dimensional generalized B-type Kadomtsev–Petviashvili equation for water waves is investigated. Through the Hirota method and Kadomtsev–Petviashvili hierarchy reduction, we obtain the first-order,higher-order, multiple rogue waves and lump solitons based on the solutions in terms of the Gramian. The first-order rogue waves are the line rogue waves which arise from the constant background and then disappear into the constant background again, while the first-order lump solitons propagate stably. Interactions among several first-order rogue waves which are described by the multiple rogue waves are presented. Elastic interactions of several first-order lump solitons are also presented. We find that the higher-order rogue waves and lump solitons can be treated as the superpositions of several first-order ones, while the interaction between the second-order lump solitons is inelastic.展开更多
Two-dimensional(2D)materials have been recognized as a type of potential channel material to replace silicon in future field-effect transistors(FETs)by the International Technology Roadmap for Semiconductors(ITRS)and ...Two-dimensional(2D)materials have been recognized as a type of potential channel material to replace silicon in future field-effect transistors(FETs)by the International Technology Roadmap for Semiconductors(ITRS)and its succesor the International Roadmap for Devices and Systems(IRDS)[1−4].Substantial first principle quantum transport simulations have predicted that many 2D transistors,including those with MoS2,WSe2,phosphorene,and Bi2O2Se channels,own excellent device performance and are able to extend Moore’s law down to the sub-10 nm scale[4].展开更多
Twin-core optical fibers are applied in such fields as the optical sensing and optical communication,and propagation of the pulses,Gauss beams and laser beams in the non-Kerr media is reported.Studied in this paper ar...Twin-core optical fibers are applied in such fields as the optical sensing and optical communication,and propagation of the pulses,Gauss beams and laser beams in the non-Kerr media is reported.Studied in this paper are the coupled cubic-quintic nonlinear Schrodinger equations with variable coefficients,which describe the effects of quintic nonlinearity for the ultrashort optical pulse propagation in a twin-core optical fiber or non-Kerr medium.Based on the integrable conditions,bilinear forms are derived,and dark-dark soliton solutions can be constructed in terms of the Gramian via the Kadomtsev-Petviashvili hierarchy reduction.Propagation and interaction of the dark-dark solitons are presented and discussed through the graphic analysis.With different values of the delayed nonlinear response effect b(z),where z represents direction of the propagation,the linear-and parabolic-shaped one dark-dark soltions can be derived.Interactions between the parabolic-and periodic-shaped two dark-dark solitons are presented with b(z)as the linear and periodic functions,respectively.Directions of velocities of the two dark-dark solitons vary with z and the amplitudes of the solitons remain unchanged can be observed.Interactions between the two dark-dark solitons of different types are displayed,and we observe that the velocity of one soliton is zero and direction of the velocity of the other soliton vary with z.We find that those interactions are elastic.展开更多
Particulate matter(PM)pollution has become a serious problem worldwide and various kinds of nanofibrous filters aiming to solve the problem have been developed.It is urgent to remove PM from high-temperature pollution...Particulate matter(PM)pollution has become a serious problem worldwide and various kinds of nanofibrous filters aiming to solve the problem have been developed.It is urgent to remove PM from high-temperature pollution sources,such as industrial emissions,coal furnaces,and automobile exhaust gases.However,filtration at pollution sources remains challenging because most existing air filters are not resistant to high temperature.Herein,heat-resistant polyimide(PI)nanofibrous air filters are fabricated via a simple and scalable solution blow-spinning method.These air filters show excellent thermal stability at high temperature up to 420℃.They exhibit a filtration efficiency as high as 99.73%at ambient temperature and over 97%at 300℃.In addition,a field test shows that the filters remove>97%of PM from the car exhaust fumes.Hence,the blow-spun PI nanofibrous membranes combined with the facile preparation strategy have great potential in high temperature air filtration fields and other similar applications such as water purification and protein separation.展开更多
New-generation human body motion sensors for wearable electronics and intelligent medicine are required to comply with stringent requirements in terms of ultralight weight,flexibility,stability,biocompatibility,and ex...New-generation human body motion sensors for wearable electronics and intelligent medicine are required to comply with stringent requirements in terms of ultralight weight,flexibility,stability,biocompatibility,and extreme precision.However,conventional sensors are hard to fulfill all these criteria due to their rigid structure,high-density sensing materials used as the constituents,as well as hermetical and compact assembly strategy.Here,we report an ultralight sensing material based on radial anisotropic porous silver fiber(RAPSF),which has been manufactured by phase separation and temperature-controlled grain growth strategy on a modified blow-spinning system.The resistance of RAPSF could be dynamically adjusted depending on the deflected shape.Furthermore,an all-fiber motion sensor(AFMS)with an ultra-low density of 68.70 mg cm^(−3) and an overall weigh of 7.95 mg was fabricated via layer-by-layer assembly.The sensor exhibited outstanding flexibility,breathability,biocompatibility,and remarkable body motion recognition ability.Moreover,the AFMS was shown to have great potential as an artificial intelligence throat sensor for throat state identification at the accuracy above 85%,allowing one to spot the early onset of the viral throat illness.展开更多
In this paper, we investigate a(3+1)-dimensional generalized variable-coefficient Kadomtsev–Petviashvili equation, which can describe the nonlinear phenomena in fluids or plasmas. Painlev′e analysis is performed for...In this paper, we investigate a(3+1)-dimensional generalized variable-coefficient Kadomtsev–Petviashvili equation, which can describe the nonlinear phenomena in fluids or plasmas. Painlev′e analysis is performed for us to study the integrability, and we find that the equation is not completely integrable. By virtue of the binary Bell polynomials,bilinear form and soliton solutions are obtained, and B¨acklund transformation in the binary-Bell-polynomial form and bilinear form are derived. Soliton collisions are graphically discussed: the solitons keep their original shapes unchanged after the collision except for the phase shifts. Variable coefficients are seen to affect the motion of solitons: when the variable coefficients are chosen as the constants, solitons keep their directions unchanged during the collision; with the variable coefficients as the functions of the temporal coordinate, the one soliton changes its direction.展开更多
In the biased guest-host photorefractive polymer,the Manakov equations can be used to describe the optical soliton propagation and interaction.Hereby for such equations,via the Hirota method and symbolic computation,a...In the biased guest-host photorefractive polymer,the Manakov equations can be used to describe the optical soliton propagation and interaction.Hereby for such equations,via the Hirota method and symbolic computation,analytic soliton solutions in the bright-dark and dark-dark forms are obtained.Based on the choice of photorefractive polymer parameter and incident-optical-beam parameter,the bright-dark and dark-dark solitons as well as their interaction can occur in the polymer when the total intensity is much lower than the background illumination,and our analysis indicates that the incident light with different polarization directions influence little on the soliton propagation.γ,representing the soliton intensity far away from the soliton center,determines the appearance of bright or dark soliton under the background illumination.Through the graphic and asymptotic analysis on the two-soliton solutions along with the different γ,we find that there exist the elastic and inelastic interactions between the bright-dark solitons,while the interactions between the dark-dark solitons are always elastic.展开更多
Under investigation in this paper is a(3 + 1)-dimensional variable-coefficient Kadomtsev–Petviashvili equation, which describes the propagation of surface and internal water waves. By virtue of the binary Bell polyno...Under investigation in this paper is a(3 + 1)-dimensional variable-coefficient Kadomtsev–Petviashvili equation, which describes the propagation of surface and internal water waves. By virtue of the binary Bell polynomials,symbolic computation and auxiliary independent variable, the bilinear forms, soliton solutions, B¨acklund transformations and Lax pair are obtained. Variable coefficients of the equation can affect the solitonic structure, when they are specially chosen, while curved and linear solitons are illustrated. Elastic collisions between/among two and three solitons are discussed, through which the solitons keep their original shapes invariant except for some phase shifts.展开更多
Investigation in this paper is given to the reduced Maxwell-Bloch equations with variable coefficients,describing the propagation of the intense ultra-short optical pulses through an inhomogeneous two-level dielectric...Investigation in this paper is given to the reduced Maxwell-Bloch equations with variable coefficients,describing the propagation of the intense ultra-short optical pulses through an inhomogeneous two-level dielectric medium.We apply the Hirota method and symbolic computation to study such equations. With the help of the dependent variable transformations, we present the variable-coefficient-dependent bilinear forms. Then, we construct the one-, two-and N-soliton solutions in analytic forms for them.展开更多
The Korteweg-de Vries(Kd V)-type equations have been seen in fluid mechanics,plasma physics and lattice dynamics,etc. This paper will address the bilinearization problem for some higher-order Kd V equations. Based on ...The Korteweg-de Vries(Kd V)-type equations have been seen in fluid mechanics,plasma physics and lattice dynamics,etc. This paper will address the bilinearization problem for some higher-order Kd V equations. Based on the relationship between the bilinear method and Bell-polynomial scheme,with introducing an auxiliary independent variable,we will present the general bilinear forms. By virtue of the symbolic computation,one-and two-soliton solutions are derived.展开更多
基金Supported by the National Natural Science Foundation of China under Grants Nos 11374041 and 11374042, the National Basic Research Program of China under Grants No 2010CB923202, and the Fund of State Key Laboratory of Information Photonics and Optical Communications of Beijing University of Posts and Telecommunications.
基金supported by the Fundamental Research Funds for the Central Universities,and the National Natural Science Foundation of China(Grant Nos.91964101 and 11905016)a Project of Shandong Provincial Higher Educational Science and Technology Program(Grant No.J18KB108)+2 种基金the Fund from the State Key Laboratory of Artificial Microstructure&Mesoscopic Physicsthe Fund of the State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)the support from the High-performance Computing Platform of Peking University。
文摘The degradation mechanism of the all-inorganic perovskite solar cells in the ambient environment remains unclear.In this paper,water and oxygen molecule adsorptions on the all-inorganic perovskite(CsPbBr_(3))surface are studied by density-functional theory calculations.In terms of the adsorption energy,the water molecules are more susceptible than the oxygen molecules to be adsorbed on the CsPbBr_(3)surface.The water molecules can be adsorbed on both the CsBr-and PbBr-terminated surfaces,but the oxygen molecules tend to be selectively adsorbed on the CsBr-terminated surface instead of the PbBr-terminated one due to the significant adsorption energy difference.While the adsorbed water molecules only contribute deep states,the oxygen molecules introduce interfacial states inside the bandgap of the perovskite,which would significantly impact the chemical and transport properties of the perovskite.Therefore,special attention should be paid to reduce the oxygen concentration in the environment during the device fabrication process so as to improve the stability and performance of the CsPbBr_(3)-based devices.
基金Project supported by the BUPT Excellent Ph.D.Students Foundation(Grant No.CX2019201)the National Natural Science Foundation of China(Grant Nos.11772017 and 11805020)+1 种基金the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China(Grant No.IPOC:2017ZZ05)the Fundamental Research Funds for the Central Universities of China(Grant No.2011BUPTYB02)。
文摘Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674036 and 11875008)Beijing Youth Top Notch Talent Support Program,China(Grant No.2017000026833ZK08)+1 种基金Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications,Grant No.IPOC2019ZZ01)Fundamental Research Funds for the Central Universities,China(Grant No.500419305).
文摘A coupled(2+1)-dimensional variable coefficient Ginzburg-Landau equation is studied.By virtue of the modified Hirota bilinear method,the bright one-soliton solution of the equation is derived.Some phenomena of soliton propagation are analyzed by setting different dispersion terms.The influences of the corresponding parameters on the solitons are also discussed.The results can enrich the soliton theory,and may be helpful in the manufacture of optical devices.
基金the National Natural Science Foundation of China(Grant No.11871116)the Fundamental Research Funds for the Central Universities of China(Grant No.2019XD-A11)the BUPT Innovation and Entrepreneurship Support Program,Beijing University of Posts and Telecommunications,and the National Scholarship for Doctoral Students of China.
文摘The atmosphere is an evolutionary agent essential to the shaping of a planet,while in oceanic science and daily life,liquids are commonly seen.In this paper,we investigate a generalized variable-coefficient Korteweg-de Vriesmodified Korteweg-de Vries equation for the atmosphere,oceanic fluids and plasmas.With symbolic computation,beginning with a presumption,we work out certain scaling transformations,bilinear forms through the binary Bell polynomials and our scaling transformations,N solitons(with N being a positive integer)via the aforementioned bilinear forms and bilinear auto-Bäcklund transformations through the Hirota method with some solitons.In addition,Painlevé-type auto-Bäcklund transformations with some solitons are symbolically computed out.Respective dependences and constraints on the variable/constant coefficients are discussed,while those coefficients correspond to the quadratic-nonlinear,cubic-nonlinear,dispersive,dissipative and line-damping effects in the atmosphere,oceanic fluids and plasmas.
基金supported by the National Natural Science Foundation of China(No.91964101)the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)and the Research Innovation Fund for College Students of Beijing University of Posts and Telecommunications.
文摘Owing to the high carrier mobility,two-dimensional(2D)gallium antimonite(GaSb)is a promising channel material for field-effect transistors(FETs)in the post-silicon era.We investigated the ballistic performance of the 2D GaSb metal-oxide-semiconductor FETs with a 10 nm-gate-length by the ab initio quantum transport simulation.Because of the wider bandgap and better gate-control ability,the performance of the 10-nm monolayer(ML)GaSb FETs is generally superior to the bilayer counterparts,including the three-to-four orders of magnitude larger on-current.Via hydrogenation,the delaytime and power consumption can be further enhanced with magnitude up to 35%and 57%,respectively,thanks to the expanded bandgap.The 10-nm ML GaSb FETs can almost meet the International Technology Roadmap for Semiconductors(ITRS)for high-performance demands in terms of the on-state current,intrinsic delay time,and power-delay product.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11604019,61574020,and 61376018)the Ministry of Science and Technology of China(Grant No.2016YFA0301300)+1 种基金the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),Chinathe Fundamental Research Funds for the Central Universities,China(Grant No.2016RCGD22)
文摘Tunneling field effect transistors(TFETs) based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low power devices. Here,we investigate the TFETs based on two different integration types: in-plane and vertical heterostructures composed of two kinds of layered phosphorous(β-P and δ-P) by ab initio quantum transport simulations. NDR effects have been observed in both in-plane and vertical heterostructures, and the effects become significant with the highest peak-to-valley ratio(PVR)when the intrinsic region length is near zero. Compared with the in-plane TFET based on β-P and δ-P, better performance with a higher on/off current ratio of - 10-6 and a steeper subthreshold swing(SS) of - 23 mV/dec is achieved in the vertical TFET. Such differences in the NDR effects, on/off current ratio and SS are attributed to the distinct interaction nature of theβ-P and δ-P layers in the in-plane and vertical heterostructures.
基金Supported by the National Natural Science Foundation of China under Grant No 11374041, the National Basic Research Program of China under Grant No 2010CB923202, and the Fund of State Key Laboratory of Information Photonics and Optical Communications of Bei]ing University of Posts and Telecommunications.
文摘A hybrid plasmonic waveguide, consisting of two dielectric nanowires symmetrically put at the opposite corner angles of a rhombic metM, is proposed and numerically analyzed by the finite-element method. Simulations show that the present waveguide can achieve the millimeter propagation distance (1244 μm) and deep subwavelength mode area (5.5 × 10-3 μm2), simultaneously. Compared with the previous hybrid waveguides based on cylinder nanowires or fiat films, the rhombie corner angles enable our waveguide to achieve both longer propagation distance and smaller mode area. This is due to the enhanced coupling between the dielectric guided mode in nanowires and the surface plasmon polariton mode at rhombic surface. Furthermore, the extreme confinement near the rhombic corner angles can strengthen the light-matter interaction greatly and make the present waveguide useful in many applications, such as nonlinear photonics, high-quality nanolazers and nanophotonic waveguides.
基金This study was supported by the National Basic Research of China(Grants 2015CB932500)National Natural Science Foundations of China(Grant 51661135025 and 51522207)+1 种基金BUPT Excellent Ph.D.Students Foundation(Grant GX2017205)State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications).
文摘A kind of pollution known as electromagnetic interference(EMI),which results from ubiquitous usage of various electronic communication and military radar equipment,has been receiving increasing attention recently.However,large-area EMI shielding on transparent and/or curved surfaces,including building windows,curved glass wall,and special requirements spaces(SRSs),remains hard to achieve.In this paper,a silver nanofiber(AgNF)based flexible and transparent EMI shielding film was successfully assembled via a room-temperature roll-to-roll production method.For transparent application scenario,AgNF with 89%transmittance in visible range and 1μm thickness shows~20 dB shielding efficiency(EMI SE).On the other hand,total shielding(>50 dB)is obtained when the thickness of AgNF increases to 10μm,while its transmittance in visible range remains higher than 75%.Considering the facile and scale-free production technology,this material can be readily applied in large-scale,transparent,and/or SRSs EMI shielding.
基金supported by the National Nature Science Foundation of China under Grant No.11871116Fundamental Research Funds for the Central Universities of China under Grant No. 2019XD-A11。
文摘Water waves are one of the most common phenomena in nature, the studies of which help energy development, marine/offshore engineering, hydraulic engineering, mechanical engineering, etc. Hereby, symbolic computation is performed on the Boussinesq–Burgers system for shallow water waves in a lake or near an ocean beach. For the water-wave horizontal velocity and height of the water surface above the bottom, two sets of the bilinear forms through the binary Bell polynomials and N-soliton solutions are worked out, while two auto-B?cklund transformations are constructed together with the solitonic solutions, where N is a positive integer. Our bilinear forms, N-soliton solutions and B?cklund transformations are different from those in the existing literature. All of our results are dependent on the waterwave dispersive power.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11772017,11272023,and 11471050by the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China(IPOC:2017ZZ05)by the Fundamental Research Funds for the Central Universities of China under Grant No.2011BUPTYB02
文摘In this paper, the(3+1)-dimensional generalized B-type Kadomtsev–Petviashvili equation for water waves is investigated. Through the Hirota method and Kadomtsev–Petviashvili hierarchy reduction, we obtain the first-order,higher-order, multiple rogue waves and lump solitons based on the solutions in terms of the Gramian. The first-order rogue waves are the line rogue waves which arise from the constant background and then disappear into the constant background again, while the first-order lump solitons propagate stably. Interactions among several first-order rogue waves which are described by the multiple rogue waves are presented. Elastic interactions of several first-order lump solitons are also presented. We find that the higher-order rogue waves and lump solitons can be treated as the superpositions of several first-order ones, while the interaction between the second-order lump solitons is inelastic.
基金supported by the National Natural Science Foundation of China(91964101,12274002)the Fundamental Research Funds for the Central Universities,the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),the Foundation of He’nan Educational Committee(23A430015)+1 种基金the open research fund of National Center for International Research on Intelligent Nano-Materials and Detection Technology in Environmental Protection(SDGH2106)the High-performance Computing Platform of Peking University and the MatCloud+high throughput materials simulation engine.
文摘Two-dimensional(2D)materials have been recognized as a type of potential channel material to replace silicon in future field-effect transistors(FETs)by the International Technology Roadmap for Semiconductors(ITRS)and its succesor the International Roadmap for Devices and Systems(IRDS)[1−4].Substantial first principle quantum transport simulations have predicted that many 2D transistors,including those with MoS2,WSe2,phosphorene,and Bi2O2Se channels,own excellent device performance and are able to extend Moore’s law down to the sub-10 nm scale[4].
基金the National Natural Science Foundation of China under Grant Nos.11772017,11805020,11272023 and 11471050the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China(IPOC:2017ZZ05)the Fundamental Research Funds for the Central Universities of China under Grant No.2011BUPTYB02
文摘Twin-core optical fibers are applied in such fields as the optical sensing and optical communication,and propagation of the pulses,Gauss beams and laser beams in the non-Kerr media is reported.Studied in this paper are the coupled cubic-quintic nonlinear Schrodinger equations with variable coefficients,which describe the effects of quintic nonlinearity for the ultrashort optical pulse propagation in a twin-core optical fiber or non-Kerr medium.Based on the integrable conditions,bilinear forms are derived,and dark-dark soliton solutions can be constructed in terms of the Gramian via the Kadomtsev-Petviashvili hierarchy reduction.Propagation and interaction of the dark-dark solitons are presented and discussed through the graphic analysis.With different values of the delayed nonlinear response effect b(z),where z represents direction of the propagation,the linear-and parabolic-shaped one dark-dark soltions can be derived.Interactions between the parabolic-and periodic-shaped two dark-dark solitons are presented with b(z)as the linear and periodic functions,respectively.Directions of velocities of the two dark-dark solitons vary with z and the amplitudes of the solitons remain unchanged can be observed.Interactions between the two dark-dark solitons of different types are displayed,and we observe that the velocity of one soliton is zero and direction of the velocity of the other soliton vary with z.We find that those interactions are elastic.
基金This study was supported by the National Natural Science Foundation of China(Nos.51788104 and 51661135025)the National Basic Research Program of China(No.2015CB932500)China Postdoctoral Science Foundation(Nos.2018M640124 and 2019T120083).
文摘Particulate matter(PM)pollution has become a serious problem worldwide and various kinds of nanofibrous filters aiming to solve the problem have been developed.It is urgent to remove PM from high-temperature pollution sources,such as industrial emissions,coal furnaces,and automobile exhaust gases.However,filtration at pollution sources remains challenging because most existing air filters are not resistant to high temperature.Herein,heat-resistant polyimide(PI)nanofibrous air filters are fabricated via a simple and scalable solution blow-spinning method.These air filters show excellent thermal stability at high temperature up to 420℃.They exhibit a filtration efficiency as high as 99.73%at ambient temperature and over 97%at 300℃.In addition,a field test shows that the filters remove>97%of PM from the car exhaust fumes.Hence,the blow-spun PI nanofibrous membranes combined with the facile preparation strategy have great potential in high temperature air filtration fields and other similar applications such as water purification and protein separation.
基金supported by the Fundamental Research Funds for the Central Universities (2021XD-A04-1)National Natural Science Foundations of China (Grant 62104051,51661135025,51706117 and U1564205)National Basic Research of China (Grants 2018YFB0104404).
文摘New-generation human body motion sensors for wearable electronics and intelligent medicine are required to comply with stringent requirements in terms of ultralight weight,flexibility,stability,biocompatibility,and extreme precision.However,conventional sensors are hard to fulfill all these criteria due to their rigid structure,high-density sensing materials used as the constituents,as well as hermetical and compact assembly strategy.Here,we report an ultralight sensing material based on radial anisotropic porous silver fiber(RAPSF),which has been manufactured by phase separation and temperature-controlled grain growth strategy on a modified blow-spinning system.The resistance of RAPSF could be dynamically adjusted depending on the deflected shape.Furthermore,an all-fiber motion sensor(AFMS)with an ultra-low density of 68.70 mg cm^(−3) and an overall weigh of 7.95 mg was fabricated via layer-by-layer assembly.The sensor exhibited outstanding flexibility,breathability,biocompatibility,and remarkable body motion recognition ability.Moreover,the AFMS was shown to have great potential as an artificial intelligence throat sensor for throat state identification at the accuracy above 85%,allowing one to spot the early onset of the viral throat illness.
基金Supported by the National Natural Science Foundation of China under Grant No.11272023the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)under GrantNo.IPOC2013B008the Fundamental Research Funds for the Central Universities of China under Grant No.2011BUPTYB02
文摘In this paper, we investigate a(3+1)-dimensional generalized variable-coefficient Kadomtsev–Petviashvili equation, which can describe the nonlinear phenomena in fluids or plasmas. Painlev′e analysis is performed for us to study the integrability, and we find that the equation is not completely integrable. By virtue of the binary Bell polynomials,bilinear form and soliton solutions are obtained, and B¨acklund transformation in the binary-Bell-polynomial form and bilinear form are derived. Soliton collisions are graphically discussed: the solitons keep their original shapes unchanged after the collision except for the phase shifts. Variable coefficients are seen to affect the motion of solitons: when the variable coefficients are chosen as the constants, solitons keep their directions unchanged during the collision; with the variable coefficients as the functions of the temporal coordinate, the one soliton changes its direction.
基金Supported by the National Natural Science Foundation of China under Grant No.11272023the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)Supported by the Fundamental Research Funds for the Central Universities of China under Grant No.2011BUPTYB02
文摘In the biased guest-host photorefractive polymer,the Manakov equations can be used to describe the optical soliton propagation and interaction.Hereby for such equations,via the Hirota method and symbolic computation,analytic soliton solutions in the bright-dark and dark-dark forms are obtained.Based on the choice of photorefractive polymer parameter and incident-optical-beam parameter,the bright-dark and dark-dark solitons as well as their interaction can occur in the polymer when the total intensity is much lower than the background illumination,and our analysis indicates that the incident light with different polarization directions influence little on the soliton propagation.γ,representing the soliton intensity far away from the soliton center,determines the appearance of bright or dark soliton under the background illumination.Through the graphic and asymptotic analysis on the two-soliton solutions along with the different γ,we find that there exist the elastic and inelastic interactions between the bright-dark solitons,while the interactions between the dark-dark solitons are always elastic.
基金Supported by the National Natural Science Foundation of China under Grant No.11272023the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)under Grant No.IPOC2013B008the Fundamental Research Funds for the Central Universities of China under Grant No.2011BUPTYB02
文摘Under investigation in this paper is a(3 + 1)-dimensional variable-coefficient Kadomtsev–Petviashvili equation, which describes the propagation of surface and internal water waves. By virtue of the binary Bell polynomials,symbolic computation and auxiliary independent variable, the bilinear forms, soliton solutions, B¨acklund transformations and Lax pair are obtained. Variable coefficients of the equation can affect the solitonic structure, when they are specially chosen, while curved and linear solitons are illustrated. Elastic collisions between/among two and three solitons are discussed, through which the solitons keep their original shapes invariant except for some phase shifts.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11772017,11272023,11471050the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China(IPOC:2017ZZ05)the Fundamental Research Funds for the Central Universities of China under Grant No.2011BUPTYB02
文摘Investigation in this paper is given to the reduced Maxwell-Bloch equations with variable coefficients,describing the propagation of the intense ultra-short optical pulses through an inhomogeneous two-level dielectric medium.We apply the Hirota method and symbolic computation to study such equations. With the help of the dependent variable transformations, we present the variable-coefficient-dependent bilinear forms. Then, we construct the one-, two-and N-soliton solutions in analytic forms for them.
基金Supported by the National Natural Science Foundation of China under Grant No.11272023the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)by the Fundamental Research Funds for the Central Universities of China under Grant No.2011BUPTYB02
文摘The Korteweg-de Vries(Kd V)-type equations have been seen in fluid mechanics,plasma physics and lattice dynamics,etc. This paper will address the bilinearization problem for some higher-order Kd V equations. Based on the relationship between the bilinear method and Bell-polynomial scheme,with introducing an auxiliary independent variable,we will present the general bilinear forms. By virtue of the symbolic computation,one-and two-soliton solutions are derived.