Angular momentum, a fundamental physical quantity, can be divided into spin angular momentum(SAM) and orbital angular momentum(OAM) in electromagnetic waves. Helically-phased or twisted light beams carrying OAM that e...Angular momentum, a fundamental physical quantity, can be divided into spin angular momentum(SAM) and orbital angular momentum(OAM) in electromagnetic waves. Helically-phased or twisted light beams carrying OAM that exploit the spatial structure physical dimension of electromagnetic waves have benefited wide applications ranging from optical manipulation to quantum information processing. Using the two distinct properties of OAM, i.e., inherent orthogonality and unbounded states in principle, one can develop OAM modulation and OAM multiplexing techniques for twisted optical communications. OAM multiplexing is an alternative space-division multiplexing approach employing an orthogonal mode basis related to the spatial phase structure. In this paper, we review the recent progress in twisted optical communications using OAM in free space and fiber. The basic concept of momentum, angular momentum, SAM, OAM and OAM-carrying twisted optical communications,key techniques and devices of OAM generation/(de)multiplexing/detection, high-capacity spectrally-efficient free-space OAM links, fiber-based OAM links, and OAM processing functions are presented. Ultra-high spectral efficiency and petabit-scale freespace data links are achieved benefiting from OAM multiplexing. The key techniques and challenges of twisted optical communications are also discussed. Twisted optical communications using OAM are compatible with other existing physical dimensions such as frequency/wavelength, amplitude, phase, polarization and time, opening a possible way to facilitate continuous increase of the aggregate transmission capacity and spectral efficiency through N-dimensional multiplexing.展开更多
Unsteady cavitating turbulent flow around twisted hydrofoil is simulated with Zwart cavitation model combined with the filter-based density correction model（FBDCM）.Numerical results simulated the entire process of t...Unsteady cavitating turbulent flow around twisted hydrofoil is simulated with Zwart cavitation model combined with the filter-based density correction model（FBDCM）.Numerical results simulated the entire process of the 3-D cavitation shedding including the re-entrant jet and side-entrant jet dynamics and were compared with the available experimental data.The distribution of finite-time Lyapunov exponent（FTLE） was used to analyze the 3-D behavior of the re-entrant jet from the Lagrangian viewpoint,which shows that it can significantly influence the particle trackers in the attached cavity.Further analysis indicates that the different flow behavior on the suction side with different attack angle can be identified with Lagrangian coherent structures（LCS）.For the area with a large attack angle,the primary shedding modifies the flow pattern on the suction side.With the decrease in attack angle,the attached cavity tends to be steady,and LCS A is close to the upper wall.A further decrease in attack angle eliminates LCS A in the boundary layer.The FTLE distribution also indicates that the decreasing attack angle induces a thinner boundary layer along the foil surface on the suction side.展开更多
This paper deals with the experimental investigation on Nusselt number,friction factor and thermal en-hancement factor of a double pipe heat exchanger equipped with twisted tape consisting wire nails(WN-TT) and plain ...This paper deals with the experimental investigation on Nusselt number,friction factor and thermal en-hancement factor of a double pipe heat exchanger equipped with twisted tape consisting wire nails(WN-TT) and plain twisted tapes(P-TT) with three different twist ratios of y 2.0,4.4 and 6.0. Test runs are conducted using the water as the working fluid with Reynolds number range between 2000 and 12000 for WN-TT and P-TT. It is found that Nusselt number,friction factor and thermal enhancement factor in the tube equipped with WN-TT appreciably higher than those in the tube fitted with P-TT and plain tube. Over the range considered Nusselt number,friction factor and thermal enhancement factor in a tube with WN-TT are respectively,1.08 to 1.31,1.1 to 1.75 and 1.05 to 1.13 times of those in tube with P-TT. The better performance of WN-TT is due to combined effects of the follow-ing factors:(1) common swirling flow generated by P-TT,(2) additional turbulence offered by the wire nails. Em-pirical correlations for Nusselt number,friction factor and thermal enhancement factor are also formulated from the experimental results of WN-TT and P-TT.展开更多
We show that the support of an irreducible weight module over the twisted Heisenberg-Virasoro algebra, which has an infinite-dimensional weight space, coincides with the weight lattice and that all nontrivial weight s...We show that the support of an irreducible weight module over the twisted Heisenberg-Virasoro algebra, which has an infinite-dimensional weight space, coincides with the weight lattice and that all nontrivial weight spaces of such a module are infinite dimensional. As a corollary, we obtain that every irreducible weight module over the twisted Heisenber-Virasoro algebra, having a nontrivial finite-dimensional weight space, is a Harish-Chandra module （and hence is either an irreducible highest or lowest weight module or an irreducible module from the intermediate series）.展开更多
Heat transfer,friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes（STT） and plain twisted tapes（PTT） are investigated experimentally u...Heat transfer,friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes（STT） and plain twisted tapes（PTT） are investigated experimentally using the water as working fluid.The tapes（STT and PTT） have three twist ratios（y=2.0,4.4 and 6.0） and the Reynolds number ranges from 2000 to 12000.The experimental results reveal that heat transfer rate,friction factor and thermal enhancement factor in the tube equipped with STT are significantly higher than those fitted with PTT. The additional disturbance and secondary flow in the vicinity of the tube wall generated by STT are higher compared to that induced by the PTT is referred as the reason for better performance.Over the range considered,the Nusselt number,friction factor and thermal enhancement factor in a tube with STT are respectively,1.03 to 1.14,1.05 to 1.25 and 1.02 to 1.06 times of those in tube with PTT.An empirical correlation is also formulated to match with experimental data of Nusselt number and friction factor for STT and PTT.展开更多
This paper gives a sufficient and necessary condition for twisted products to be weak Hopf algebras, moreover, gives a description for smash products to be weak Hopf algebras. It respectively generalizes R.K.Molnar...This paper gives a sufficient and necessary condition for twisted products to be weak Hopf algebras, moreover, gives a description for smash products to be weak Hopf algebras. It respectively generalizes R.K.Molnar's major result and I.Boca's result.展开更多
We study molybdenum disulfide （MoS2） structures generated by folding single-layer and bilayer MoS2 flakes. We find that this modified layer stacking leads to a decrease in the interlayer coupling and an enhancement ...We study molybdenum disulfide （MoS2） structures generated by folding single-layer and bilayer MoS2 flakes. We find that this modified layer stacking leads to a decrease in the interlayer coupling and an enhancement of the photoluminescence emission yield. We additionally find that folded single-layer MoS2 structures show a contribution to photoluminescence spectra of both neutral and charged excitons, which is a characteristic feature of single-layer MoS2 that has not been observed in multilayer MoS2. The results presented here open the door to fabrication of multilayered MoS2 samples with high optical absorption while maintaining the advantageous enhanced photoluminescence emission of single-layer MoS2 by controllably twisting the MoS2 layers.展开更多
Let G be an abelian group, B the G-graded λ-Hopf algebra with A being a bicharacter on G. By introducing some new twisted algebras （coalgebras）, we investigate the basic properties of the graded antipode and the st...Let G be an abelian group, B the G-graded λ-Hopf algebra with A being a bicharacter on G. By introducing some new twisted algebras （coalgebras）, we investigate the basic properties of the graded antipode and the structure for B. We also prove that a G-graded λ-Hopf algebra can be embedded in a usual Hopf algebra. As an application, it is given that if G is a finite abelian group then the graded antipode of a finite dimensional G-graded A-Hopf algebra is invertible.展开更多
The paper presents an experimental investigation on enhanced heat transfer and pressure loss characteristics by using single, double, triple, and quadruple twisted-tape inserts in a round tube having a uniform heat-fl...The paper presents an experimental investigation on enhanced heat transfer and pressure loss characteristics by using single, double, triple, and quadruple twisted-tape inserts in a round tube having a uniform heat-fluxed wall. The investigation has been conducted in the heat exchanger tube inserted with various twisted-tape numbers for co- and counter-twist arrangements for the turbulent air flow, Reynolds number （Re） from 5300 to 24000. The typical single twisted-tape inserts at two twist ratios, y/w = 4 and 5, are used as the base case, while the other multiple twisted-tape inserts are aty/w = 4 only. The experimental results of heat transfer and pressure drop in terms of Nusselt number （Nu） and friction factor 00, respectively, reveal that Nu increases with the increment of Re and of twisted-tape number. The values of Nu for the inserted tube are in a range of 1.15-2.12 times that for the plain tube while f is 1.9-4.1 times. The thermal enhancement factor of the inserted tube under similar pumping power is evaluated and found to be above unity except for the single and the double co-twisted tapes. The quadruple counter-twisted tape insert provides the maximum thermal performance.展开更多
Using exact quantum Monte Carlo method, we examine the recent novel electronic states seen in magicangle graphene superlattices. From the Hubbard model on a double-layer honeycomb lattice with a rotation angle θ=1:08...Using exact quantum Monte Carlo method, we examine the recent novel electronic states seen in magicangle graphene superlattices. From the Hubbard model on a double-layer honeycomb lattice with a rotation angle θ=1:08°, we reveal that an antiferromagnetically ordered Mott insulator emerges beyond a critical U_c at half filling, and with a small doping, the pairing with d+id symmetry dominates over other pairings at low temperature. The effective d+id pairing interaction strongly increases as the on-site Coulomb interaction increases, indicating that the superconductivity is driven by electron-electron correlation. Our non-biased numerical results demonstrate that the twisted bilayer graphene shares the similar superconducting mechanism of high temperature superconductors, which is a new and ideal platform for further investigating the strongly correlated phenomena.展开更多
Some basic properties of the antipode of an N0I-graded x-Hopf algebra are studied. Also, several equivalent conditions of an N0I-graded x-bialgebra (x-Hopf algebra) are given.
Recent advances in twisted van der Waals heterostructure superlattices have emerged as a powerful and attractive platform for exploring novel condensed matter physics due to the interplay between the moirépotenti...Recent advances in twisted van der Waals heterostructure superlattices have emerged as a powerful and attractive platform for exploring novel condensed matter physics due to the interplay between the moirépotential and Coulomb interactions.The moirésuperlattices act as a periodic confinement potential in space to capture interlayer excitons(IXs),resulting in moiréexciton arrays,which provide opportunities for quantum emitters and many-body physics.The observation of moiréIXs in twisted transition-metal dichalcogenide(TMD)heterostructures has recently been widely reported.However,the capture and study of the moiréintralayer excitons based on TMD twisted homobilayer(T-HB)remain elusive.Here,we report the observation of moiréintralayer excitons in a WSe_(2)/WSe_(2) T-HB with a small twist angle by measuring PL spectrum.The multiple split peaks with an energy range of 1.55-1.73 eV are different from that of the monolayer WSe_(2) exciton peaks.The split peaks were caused by the trapping of intralayer excitons via the moirépotential.The confinement effect of the moirépotential on the moiréintralayer excitons was further demonstrated by the changing of temperature,laser power,and valley polarization.Our findings provide a new avenue for exploring new correlated quantum phenomena and their applications.展开更多
Diagnosability of a multiprocessor system is one important study topic. In 2012, Peng et al. proposed the g-good-neighbor diagnosability that restrains every fault-free node to contain at least g fault-free neighbors....Diagnosability of a multiprocessor system is one important study topic. In 2012, Peng et al. proposed the g-good-neighbor diagnosability that restrains every fault-free node to contain at least g fault-free neighbors. The locally twisted cube LTQ_n has many good properties. In this paper, we show that the 1-good-neighbor connectivity κ~1(LTQ_n) = 2n-2 and the 1-good-neighbor diagnosability of LTQ_n is 2n-1 under the PMC model for n ≥ 4 and the MM~*model for n ≥ 5.展开更多
In a multiprocessor systems, it is important to local and to replace the faulty processors to maintain systempsilas high reliability. The fault diagnosis, which is the process of identifying fault processors in a mult...In a multiprocessor systems, it is important to local and to replace the faulty processors to maintain systempsilas high reliability. The fault diagnosis, which is the process of identifying fault processors in a multiprocessor system through testing. The conditional diagnosis requires that for each processor u in a system, all the processors that are directly connected to u do not fail at the same time. In this paper, we study the conditional diagnosability of the n-dimensional locally twisted cubes. After showing some properties of the locally twisted cubes, we prove that it under the PMC model is 4n – 7 for n ≥ 5.展开更多
A certain variety of non-switched polynomials provides a uni-figure representation for a wide range of linear functional equations. This is properly adapted for the calculations. We reinterpret from this point of view...A certain variety of non-switched polynomials provides a uni-figure representation for a wide range of linear functional equations. This is properly adapted for the calculations. We reinterpret from this point of view a number of algorithms.展开更多
A novel semiconductor laser system is presented based on a twisted fiber.To study the period-control and chaos-anticontrol of the laser system,we design a type of optic path as a control setup using the combination of...A novel semiconductor laser system is presented based on a twisted fiber.To study the period-control and chaos-anticontrol of the laser system,we design a type of optic path as a control setup using the combination of the twisted fiber and the polarization controller while we present a physical dynamics model of the delayed dual-feedback laser containing the twisted fiber effect.We give an analysis of the effect of the twisted fiber on the laser.We use the effects of the delayed phase and the rotation angle of the twisted fiber and the characteristics of the system to achieve control of the laser.The laser is deduced to a stable state,a double-periodic state,a period-6 state,a period-8 state,a period-9 state,a multi-period state,beat phenomenon,and so on.The periodic laser can be anti-controlled to chaos.Some chaos-anti-control area is found.The laser system is very useful for the study of chaos-control of the laser setup and the applications of some physics effects.展开更多
In this paper,we show the relation between the existence of twisted conical K?hler-Ricci solitons and the greatest log Bakry-Emery-Ricci lower bound on Fano manifolds.This is based on our proofs of some openness theor...In this paper,we show the relation between the existence of twisted conical K?hler-Ricci solitons and the greatest log Bakry-Emery-Ricci lower bound on Fano manifolds.This is based on our proofs of some openness theorems on the existence of twisted conical Kahler-Ricci solitons,which generalize Donaldson’s existence conjecture and the openness theorem of the conical K?hler-Einstein metrics to the conical soliton case.展开更多
Let R be a ring and S a cancellative and torsion-free monoid and 〈 a strict order on S. If either （S,≤） satisfies the condition that 0 ≤ s for all s ∈ S, or R is reduced, then the ring [[R^S,≤]] of the generali...Let R be a ring and S a cancellative and torsion-free monoid and 〈 a strict order on S. If either （S,≤） satisfies the condition that 0 ≤ s for all s ∈ S, or R is reduced, then the ring [[R^S,≤]] of the generalized power series with coefficients in R and exponents in S has the same triangulating dimension as R. Furthermore, if R is a PWP ring, then so is [[R^S,≤]].展开更多
We demonstrate a photonic analog of twisted bilayer graphene that has ultra-flat photonic bands and exhibits extreme slow-light behavior.Our twisted bilayer photonic device,which has an operating wavelength in the C-b...We demonstrate a photonic analog of twisted bilayer graphene that has ultra-flat photonic bands and exhibits extreme slow-light behavior.Our twisted bilayer photonic device,which has an operating wavelength in the C-band of the telecom window,uses two crystalline silicon photonic crystal slabs separated by a methyl methacrylate tunneling layer.We numerically determine the magic angle using a finite-element method and the corresponding photonic band structure,which exhibits a flat band over the entire Brillouin zone.This flat band causes the group velocity to approach zero and introduces light localization,which enhances the electromagnetic field at the expense of bandwidth.Using our original plane-wave continuum model,we find that the photonic system has a larger band asymmetry.The band structure can easily be engineered by adjusting the device geometry,giving significant freedom in the design of devices.Our work provides a fundamental understanding of the photonic properties of twisted bilayer photonic crystals and opens the door to the nanoscale-based enhancement of nonlinear effects.展开更多
基金supported by the National Basic Research Program of China(Grant No.2014CB340004)the National Natural Science Foundation of China(Grant Nos.11574001,61761130082,11774116,11274131,and61222502)+3 种基金the Royal Society-Newton Advanced Fellowshipthe National Program for Support of Top-notch Young Professionalsthe Yangtze River Excellent Young Scholars Program,the Natural Science Foundation of Hubei Province of China(Grant No.2018CFA048)the Program for HUST Academic Frontier Youth Team
文摘Angular momentum, a fundamental physical quantity, can be divided into spin angular momentum(SAM) and orbital angular momentum(OAM) in electromagnetic waves. Helically-phased or twisted light beams carrying OAM that exploit the spatial structure physical dimension of electromagnetic waves have benefited wide applications ranging from optical manipulation to quantum information processing. Using the two distinct properties of OAM, i.e., inherent orthogonality and unbounded states in principle, one can develop OAM modulation and OAM multiplexing techniques for twisted optical communications. OAM multiplexing is an alternative space-division multiplexing approach employing an orthogonal mode basis related to the spatial phase structure. In this paper, we review the recent progress in twisted optical communications using OAM in free space and fiber. The basic concept of momentum, angular momentum, SAM, OAM and OAM-carrying twisted optical communications,key techniques and devices of OAM generation/(de)multiplexing/detection, high-capacity spectrally-efficient free-space OAM links, fiber-based OAM links, and OAM processing functions are presented. Ultra-high spectral efficiency and petabit-scale freespace data links are achieved benefiting from OAM multiplexing. The key techniques and challenges of twisted optical communications are also discussed. Twisted optical communications using OAM are compatible with other existing physical dimensions such as frequency/wavelength, amplitude, phase, polarization and time, opening a possible way to facilitate continuous increase of the aggregate transmission capacity and spectral efficiency through N-dimensional multiplexing.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.51576143,11472197)Science and Technology on Water Jet Propulsion Laboratory(Grant No.61422230101162223002)
文摘Unsteady cavitating turbulent flow around twisted hydrofoil is simulated with Zwart cavitation model combined with the filter-based density correction model（FBDCM）.Numerical results simulated the entire process of the 3-D cavitation shedding including the re-entrant jet and side-entrant jet dynamics and were compared with the available experimental data.The distribution of finite-time Lyapunov exponent（FTLE） was used to analyze the 3-D behavior of the re-entrant jet from the Lagrangian viewpoint,which shows that it can significantly influence the particle trackers in the attached cavity.Further analysis indicates that the different flow behavior on the suction side with different attack angle can be identified with Lagrangian coherent structures（LCS）.For the area with a large attack angle,the primary shedding modifies the flow pattern on the suction side.With the decrease in attack angle,the attached cavity tends to be steady,and LCS A is close to the upper wall.A further decrease in attack angle eliminates LCS A in the boundary layer.The FTLE distribution also indicates that the decreasing attack angle induces a thinner boundary layer along the foil surface on the suction side.
文摘This paper deals with the experimental investigation on Nusselt number,friction factor and thermal en-hancement factor of a double pipe heat exchanger equipped with twisted tape consisting wire nails(WN-TT) and plain twisted tapes(P-TT) with three different twist ratios of y 2.0,4.4 and 6.0. Test runs are conducted using the water as the working fluid with Reynolds number range between 2000 and 12000 for WN-TT and P-TT. It is found that Nusselt number,friction factor and thermal enhancement factor in the tube equipped with WN-TT appreciably higher than those in the tube fitted with P-TT and plain tube. Over the range considered Nusselt number,friction factor and thermal enhancement factor in a tube with WN-TT are respectively,1.08 to 1.31,1.1 to 1.75 and 1.05 to 1.13 times of those in tube with P-TT. The better performance of WN-TT is due to combined effects of the follow-ing factors:(1) common swirling flow generated by P-TT,(2) additional turbulence offered by the wire nails. Em-pirical correlations for Nusselt number,friction factor and thermal enhancement factor are also formulated from the experimental results of WN-TT and P-TT.
基金NSF Grants 10471096,10571120 of China"One Hundred Talents Program"from the University of Science and Technology of China
文摘We show that the support of an irreducible weight module over the twisted Heisenberg-Virasoro algebra, which has an infinite-dimensional weight space, coincides with the weight lattice and that all nontrivial weight spaces of such a module are infinite dimensional. As a corollary, we obtain that every irreducible weight module over the twisted Heisenber-Virasoro algebra, having a nontrivial finite-dimensional weight space, is a Harish-Chandra module （and hence is either an irreducible highest or lowest weight module or an irreducible module from the intermediate series）.
文摘Heat transfer,friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes（STT） and plain twisted tapes（PTT） are investigated experimentally using the water as working fluid.The tapes（STT and PTT） have three twist ratios（y=2.0,4.4 and 6.0） and the Reynolds number ranges from 2000 to 12000.The experimental results reveal that heat transfer rate,friction factor and thermal enhancement factor in the tube equipped with STT are significantly higher than those fitted with PTT. The additional disturbance and secondary flow in the vicinity of the tube wall generated by STT are higher compared to that induced by the PTT is referred as the reason for better performance.Over the range considered,the Nusselt number,friction factor and thermal enhancement factor in a tube with STT are respectively,1.03 to 1.14,1.05 to 1.25 and 1.02 to 1.06 times of those in tube with PTT.An empirical correlation is also formulated to match with experimental data of Nusselt number and friction factor for STT and PTT.
基金This work is supported by National Natural Science Foundation of Chinaby the excellent doctorate fund of Nanjing agricultural university
文摘This paper gives a sufficient and necessary condition for twisted products to be weak Hopf algebras, moreover, gives a description for smash products to be weak Hopf algebras. It respectively generalizes R.K.Molnar's major result and I.Boca's result.
文摘We study molybdenum disulfide （MoS2） structures generated by folding single-layer and bilayer MoS2 flakes. We find that this modified layer stacking leads to a decrease in the interlayer coupling and an enhancement of the photoluminescence emission yield. We additionally find that folded single-layer MoS2 structures show a contribution to photoluminescence spectra of both neutral and charged excitons, which is a characteristic feature of single-layer MoS2 that has not been observed in multilayer MoS2. The results presented here open the door to fabrication of multilayered MoS2 samples with high optical absorption while maintaining the advantageous enhanced photoluminescence emission of single-layer MoS2 by controllably twisting the MoS2 layers.
基金Supported by the National Natural Science Foundation of ChinaYangzhou University Natural Science Foundation
文摘Let G be an abelian group, B the G-graded λ-Hopf algebra with A being a bicharacter on G. By introducing some new twisted algebras （coalgebras）, we investigate the basic properties of the graded antipode and the structure for B. We also prove that a G-graded λ-Hopf algebra can be embedded in a usual Hopf algebra. As an application, it is given that if G is a finite abelian group then the graded antipode of a finite dimensional G-graded A-Hopf algebra is invertible.
基金the Thailand Research Fund(TRF)(Grant No.Ph D/0143/2552)
文摘The paper presents an experimental investigation on enhanced heat transfer and pressure loss characteristics by using single, double, triple, and quadruple twisted-tape inserts in a round tube having a uniform heat-fluxed wall. The investigation has been conducted in the heat exchanger tube inserted with various twisted-tape numbers for co- and counter-twist arrangements for the turbulent air flow, Reynolds number （Re） from 5300 to 24000. The typical single twisted-tape inserts at two twist ratios, y/w = 4 and 5, are used as the base case, while the other multiple twisted-tape inserts are aty/w = 4 only. The experimental results of heat transfer and pressure drop in terms of Nusselt number （Nu） and friction factor 00, respectively, reveal that Nu increases with the increment of Re and of twisted-tape number. The values of Nu for the inserted tube are in a range of 1.15-2.12 times that for the plain tube while f is 1.9-4.1 times. The thermal enhancement factor of the inserted tube under similar pumping power is evaluated and found to be above unity except for the single and the double co-twisted tapes. The quadruple counter-twisted tape insert provides the maximum thermal performance.
基金supported by the National Natural Science Foundation of China(11374034 and 11334012)Beijing Natural Science Foundation(1192011)+1 种基金support of HSCC of Beijing Normal Universitythe Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund
文摘Using exact quantum Monte Carlo method, we examine the recent novel electronic states seen in magicangle graphene superlattices. From the Hubbard model on a double-layer honeycomb lattice with a rotation angle θ=1:08°, we reveal that an antiferromagnetically ordered Mott insulator emerges beyond a critical U_c at half filling, and with a small doping, the pairing with d+id symmetry dominates over other pairings at low temperature. The effective d+id pairing interaction strongly increases as the on-site Coulomb interaction increases, indicating that the superconductivity is driven by electron-electron correlation. Our non-biased numerical results demonstrate that the twisted bilayer graphene shares the similar superconducting mechanism of high temperature superconductors, which is a new and ideal platform for further investigating the strongly correlated phenomena.
基金This paper is supported by the Chinese National Natural Science Foundation
文摘Some basic properties of the antipode of an N0I-graded x-Hopf algebra are studied. Also, several equivalent conditions of an N0I-graded x-bialgebra (x-Hopf algebra) are given.
基金support from the Naional Natural Science Foundation of China(Grant No.61775241)Hunan province key research and development project(Grant No.2019GK2233)+5 种基金Hunan Provincial Science Fund for Distinguished Young Scholars(Grant No.2020JJ2059)the Youth Innovaticn Team(Grant No.2019012)of CSU,the Science and Technolgy Innovaton Basic Research Project of Shenzhen(Grant No.JCY120190806144418859)the National Natural Science Foundation of China (Nos.62090035,U19A2090)the Key Program of Science and Technology Department of Hunan Province(2019XK2001,2020XK2001)support of the High-Performance Complex Manufacturing Key State Lab Project,Central South University(Grant No.ZZYJKT2020-12)ZWL.thanks the support from the Australian Research Council(ARC Discovery Project,DP180102976).
文摘Recent advances in twisted van der Waals heterostructure superlattices have emerged as a powerful and attractive platform for exploring novel condensed matter physics due to the interplay between the moirépotential and Coulomb interactions.The moirésuperlattices act as a periodic confinement potential in space to capture interlayer excitons(IXs),resulting in moiréexciton arrays,which provide opportunities for quantum emitters and many-body physics.The observation of moiréIXs in twisted transition-metal dichalcogenide(TMD)heterostructures has recently been widely reported.However,the capture and study of the moiréintralayer excitons based on TMD twisted homobilayer(T-HB)remain elusive.Here,we report the observation of moiréintralayer excitons in a WSe_(2)/WSe_(2) T-HB with a small twist angle by measuring PL spectrum.The multiple split peaks with an energy range of 1.55-1.73 eV are different from that of the monolayer WSe_(2) exciton peaks.The split peaks were caused by the trapping of intralayer excitons via the moirépotential.The confinement effect of the moirépotential on the moiréintralayer excitons was further demonstrated by the changing of temperature,laser power,and valley polarization.Our findings provide a new avenue for exploring new correlated quantum phenomena and their applications.
基金supported by the National Natural Science Foundation of China(61772010)
文摘Diagnosability of a multiprocessor system is one important study topic. In 2012, Peng et al. proposed the g-good-neighbor diagnosability that restrains every fault-free node to contain at least g fault-free neighbors. The locally twisted cube LTQ_n has many good properties. In this paper, we show that the 1-good-neighbor connectivity κ~1(LTQ_n) = 2n-2 and the 1-good-neighbor diagnosability of LTQ_n is 2n-1 under the PMC model for n ≥ 4 and the MM~*model for n ≥ 5.
文摘In a multiprocessor systems, it is important to local and to replace the faulty processors to maintain systempsilas high reliability. The fault diagnosis, which is the process of identifying fault processors in a multiprocessor system through testing. The conditional diagnosis requires that for each processor u in a system, all the processors that are directly connected to u do not fail at the same time. In this paper, we study the conditional diagnosability of the n-dimensional locally twisted cubes. After showing some properties of the locally twisted cubes, we prove that it under the PMC model is 4n – 7 for n ≥ 5.
文摘A certain variety of non-switched polynomials provides a uni-figure representation for a wide range of linear functional equations. This is properly adapted for the calculations. We reinterpret from this point of view a number of algorithms.
文摘A novel semiconductor laser system is presented based on a twisted fiber.To study the period-control and chaos-anticontrol of the laser system,we design a type of optic path as a control setup using the combination of the twisted fiber and the polarization controller while we present a physical dynamics model of the delayed dual-feedback laser containing the twisted fiber effect.We give an analysis of the effect of the twisted fiber on the laser.We use the effects of the delayed phase and the rotation angle of the twisted fiber and the characteristics of the system to achieve control of the laser.The laser is deduced to a stable state,a double-periodic state,a period-6 state,a period-8 state,a period-9 state,a multi-period state,beat phenomenon,and so on.The periodic laser can be anti-controlled to chaos.Some chaos-anti-control area is found.The laser system is very useful for the study of chaos-control of the laser setup and the applications of some physics effects.
基金supported by National Natural Science Foundation of China(Grant No.12001532)supported by the Special Priority Program SPP 2026“Geometry at Infinity”from the German Research Foundation(DFG)。
文摘In this paper,we show the relation between the existence of twisted conical K?hler-Ricci solitons and the greatest log Bakry-Emery-Ricci lower bound on Fano manifolds.This is based on our proofs of some openness theorems on the existence of twisted conical Kahler-Ricci solitons,which generalize Donaldson’s existence conjecture and the openness theorem of the conical K?hler-Einstein metrics to the conical soliton case.
基金National Natural science Foundation of China(10171082)the Cultivation Fund of the Key Scientific Technical Innovation Project,Ministry of Education of ChinaTRAPOYT
文摘Let R be a ring and S a cancellative and torsion-free monoid and 〈 a strict order on S. If either （S,≤） satisfies the condition that 0 ≤ s for all s ∈ S, or R is reduced, then the ring [[R^S,≤]] of the generalized power series with coefficients in R and exponents in S has the same triangulating dimension as R. Furthermore, if R is a PWP ring, then so is [[R^S,≤]].
文摘We demonstrate a photonic analog of twisted bilayer graphene that has ultra-flat photonic bands and exhibits extreme slow-light behavior.Our twisted bilayer photonic device,which has an operating wavelength in the C-band of the telecom window,uses two crystalline silicon photonic crystal slabs separated by a methyl methacrylate tunneling layer.We numerically determine the magic angle using a finite-element method and the corresponding photonic band structure,which exhibits a flat band over the entire Brillouin zone.This flat band causes the group velocity to approach zero and introduces light localization,which enhances the electromagnetic field at the expense of bandwidth.Using our original plane-wave continuum model,we find that the photonic system has a larger band asymmetry.The band structure can easily be engineered by adjusting the device geometry,giving significant freedom in the design of devices.Our work provides a fundamental understanding of the photonic properties of twisted bilayer photonic crystals and opens the door to the nanoscale-based enhancement of nonlinear effects.
