We consider a triple zero point of nonlinear equations with O(2 symmetry, where the Jacobian has a zero eigenvalue of geometric multiplicity one and algebraic multiplicity three. We show that this triple zero point e...We consider a triple zero point of nonlinear equations with O(2 symmetry, where the Jacobian has a zero eigenvalue of geometric multiplicity one and algebraic multiplicity three. We show that this triple zero point exhibits a new bifurcation phenomenon, that is, a mode interaction of the following three paths: bifurcation points from steady states, steady states and rotating waves to standing waves, rotating waves and modulated rotating waves respectively.展开更多
In the modern higher education music curriculum system,the teacher-student interaction mode is a key factor affecting the effectiveness of piano teaching.However,the current teacher-student interaction mode in piano t...In the modern higher education music curriculum system,the teacher-student interaction mode is a key factor affecting the effectiveness of piano teaching.However,the current teacher-student interaction mode in piano teaching still has limitations,such as one-way transmission and a lack of personalized feedback.Based on constructivist learning theory and social interaction theory,combined with information technology,this paper explores the optimization strategy of interaction mode in the piano teaching process of normal universities.This study adopts classroom observation and interview methods to analyze the impact of different interaction modes on students’piano learning effectiveness,learning engagement,and autonomous learning ability.The research results show that the constructivist interactive teaching mode supported by information technology can significantly enhance students’interest in learning and playing skills,optimize the classroom teaching atmosphere,and promote the improvement of their comprehensive literacy.展开更多
With the development of globalization,intercultural communicative competence has become one of the core qualities of modern college students.As an important platform to cultivate students’language skills and cultural...With the development of globalization,intercultural communicative competence has become one of the core qualities of modern college students.As an important platform to cultivate students’language skills and cultural literacy,the innovation of college English teaching mode is essential.Based on this,this paper mainly discusses methods to effectively cultivate students’intercultural communicative competence in college English teaching from the perspective of multimodal interactive teaching mode,hoping to provide references for improving the quality of college English teaching and students’comprehensive quality.展开更多
Complex phenomena such as prolongedly undamped ultra-low frequency oscillation(ULFO)and eigenmode re-excitation are observed in the simulations of hydroelectric power systems.Emphases are put on nonlinearities and mod...Complex phenomena such as prolongedly undamped ultra-low frequency oscillation(ULFO)and eigenmode re-excitation are observed in the simulations of hydroelectric power systems.Emphases are put on nonlinearities and mode interactions,which cannot be analyzed by traditional eigen-analysis methods.In order to investigate the mechanism of the evolvement of the nonlinear dynamic process in ULFO,this paper proposes a method to analyze the mode interactions quantificationally.First,a disturbed trajectory is decoupled into a set of time-varying components.Second,transfer matrices of eigenmodes are extracted along the trajectory.Third,consecutive sequences of eigenvalues and trajectories of components are formed by a proposed technique.Based on the decoupled components and transfer matrices,the mechanisms of mode interactions and inheritance relationships between eigenmodes are analyzed.The causes and developments of the above complex phenomena are revealed by the proposed method in a test two-machine system.Meanwhile,the accuracy of the eigenmode matching technique is verified in the New England system.展开更多
The underlying effect of vortex interaction characterized by the merging and non-merging on mixing enhancement is of fundamental significance to understand the flow dynamics of strut injectors in scramjets.Starting fr...The underlying effect of vortex interaction characterized by the merging and non-merging on mixing enhancement is of fundamental significance to understand the flow dynamics of strut injectors in scramjets.Starting from a simplified configuration of a vortex generator,this study focuses on the influence of geometric parameters on vortex structures and fluid mixing through compressible Navier-Stokes(NS)simulations.By adjusting the induction of outer vortices,the inner co-rotating vortex pair exhibits two modes of interaction(merging/separation regime)reflected by closer/farther vortex centers.Defined by the zero variation rate of the inner vortex spacing,the critical state of equilibrium is determined.The critical condition is well predicted by a theoretical model based on the Biot-Savart law.Through the introduction of mixedness and mixing time,the intrinsic impact of interaction modes on fluid mixing is revealed.Compared with the vortex dynamics in the merging regime,the one in the separation regime is more effective for passive scalar mixing augmentation.With efficient material stretching characterized by the higher interface stretching factor and averaging finite-time Lyapunov exponent(FTLE),the mixing time is shortened by as much as 2.5 times in the separation regime.The implication of the present two interaction regimes in mixing enhancement physically reflected by the averaging FTLE has the potential to improve the combustion performance and shorten the combustor chamber.展开更多
Due to the independency, variability, and tailorability of software service in the open environment, the research of middleware which supports software services multi-mode interaction is thus of great importance. In t...Due to the independency, variability, and tailorability of software service in the open environment, the research of middleware which supports software services multi-mode interaction is thus of great importance. In this paper, an agent-based multi-mode interaction middleware model and its supporting system for software services were proposed. This model includes an interaction feature decomposition and configuration model to enable interaction programming, an agent-based middleware model, and a programmable coordination media based on reflection technology. The decomposition and configuration model for interaction features can assist programmers in interaction programming by analyzing and synthesizing interaction features. The agent-based middleware model provides a runtime framework for service multi-mode interaction. The programmable coordination media is able to effectively support software service coordination based on multimode interaction. To verify feasibility and efficiency of the above method, the design, implementation and performance analysis of Artemis-M3C, a multi-mode interaction middleware for software services, were introduced. The result shows that the above method is feasible and that the Artemis-M3C system is practical and effective in multi-mode interaction.展开更多
The one-dimensional interacting Kitaev chain at half filling is studied. The symmetry of the Hamiltonian is examined by dual transformations, and various physical quantities as a function of the fermion-fermion intera...The one-dimensional interacting Kitaev chain at half filling is studied. The symmetry of the Hamiltonian is examined by dual transformations, and various physical quantities as a function of the fermion-fermion interaction U are calculated systematically using the density matrix renormalization group method. A special value of interaction Up is revealed in the topological region of the phase diagram. We show that at Up the ground states are strictly two-fold degenerate even though the chain length is finite and the zero-energy peak due to the Majorana zero modes is maximally enhanced and exactly localized at the end sites. Here Up may be attractive or repulsive depending on other system parameters. We also give a qualitative understanding of the effect of interaction under the self-consistent mean field framework.展开更多
Nonlinear interactions of the two-dimensional （2D） second mode with oblique modes are studied numerically in a Mach 6.0 fiat-plate boundary layer, focusing on its selective enhancement effect on amplification of dif...Nonlinear interactions of the two-dimensional （2D） second mode with oblique modes are studied numerically in a Mach 6.0 fiat-plate boundary layer, focusing on its selective enhancement effect on amplification of different oblique waves. Evolution of oblique modes with various frequencies and spanwise wavenumbers in the presence of 2D second mode is simulated successively, using a modified parabolized stability equation （PSE） method, which is able to simulate interaction of two modes with different frequen- cies efficiently. Numerical results show that oblique modes in a broad band of frequencies and spanwise wavenumbers can be enhanced by the finite amplitude 2D second mode instability wave. The enhancement effect is accomplished by interaction of the 2D second mode, the oblique mode, and a forced mode with difference frequency. Two types of oblique modes are found to be more amplified, i.e., oblique modes with frequency close to that of the 2D second mode and low-frequency first mode oblique waves. Each of them may correspond to one type of transition routes found in transition experiments. The spanwise wavenumber of the oblique wave preferred by the nonlinear interaction is also determined by numerical simulations.展开更多
A new copper（Ⅱ） compound with imino nitroxide radicals [Cu（IM-MeImz）2].（SCN）2 （IM-meImz =2-（5-methylimidazol-4-yl）-4,4,5,5-tetramethyl-2-imidazoline- 1-oxyl） has been synthesized and characterized structura...A new copper（Ⅱ） compound with imino nitroxide radicals [Cu（IM-MeImz）2].（SCN）2 （IM-meImz =2-（5-methylimidazol-4-yl）-4,4,5,5-tetramethyl-2-imidazoline- 1-oxyl） has been synthesized and characterized structurally and magnetically. It crystallizes in monoclinic, space group P21/c with a = 9.3604（7）, b = 10.3012（7）, c = 16.6684（12）A, β = 105.0290（10）^o, V = 1552.25（19）A3, C24H34CUN10O2S2, Mr = 622.27, Z = 2, Dc = 1.331 g/cm^3,μ（MoKα） = 0.876 mm^-1, F（000） = 650, the final R = 0.0374 and wR = 0.1079. X-ray analysis demonstrates that the IM-MeImz ligand is coordinated to the copper（Ⅱ） ion as an unusual didentate chelate with a k-2 N（MeImz）,O（IM） mode in the complex. The square-planar coordination sites at Cu（Ⅱ） are occupied by two 0 and two N atoms from the imino nitroxide radicals. The complex molecules are connected as a onedimensional polymer structure by intermolecular interactions. Magnetic measurements show that there are intramolecular antiferromagnetic interactions between the Cu（Ⅱ） ion and radicals.展开更多
The variability in the Southern Ocean（SO） sea surface temperature（SST） has drawn increased attention due to its unique physical features; therefore, the temporal characteristics of the SO SST anomalies（SSTA） and...The variability in the Southern Ocean（SO） sea surface temperature（SST） has drawn increased attention due to its unique physical features; therefore, the temporal characteristics of the SO SST anomalies（SSTA） and their influence on extratropical atmospheric circulation are addressed in this study. Results from empirical orthogonal function analysis show that the principal mode of the SO SSTA exhibits a dipole-like structure, suggesting a negative correlation between the SSTA in the middle and high latitudes, which is referred to as the SO Dipole（SOD） in this study. The SOD features strong zonal symmetry, and could reflect more than 50% of total zonal-mean SSTA variability. We find that stronger（weaker） Subantarctic and Antarctic polar fronts are related to the positive（negative） phases of the SOD index, as well as the primary variability of the large-scale SO SSTA meridional gradient. During December–January–February, the Ferrel cell and the polar jet shift toward the Antarctic due to changes in the SSTA that could be associated with a positive phase of the SOD, and are also accompanied by a poleward shift of the subtropical jet. During June–July–August, in association with a positive SOD, the Ferrel cell and the polar jet are strengthened, accompanied by a strengthened subtropical jet. These seasonal differences are linked to the differences in the configuration of the polar jet and the subtropical jet in the Southern Hemisphere.展开更多
The college students are the main force of contemporary youth, their involvement in the ideological and political course of study is very favorable on their personal development. But affected by the traditional educat...The college students are the main force of contemporary youth, their involvement in the ideological and political course of study is very favorable on their personal development. But affected by the traditional education ideas, in colleges there are many deficiencies appeared in the process of ideological and political education, which have restricted the promotion of college students＇ Ideological and political awareness. This paper firstly analyzes the deficiencies of the traditional ideological and political education, discusses the key points of creating the intemet interactive mode, and puts forward the creative decision on ideological and political education based on the internet interactive mode, in hopes of providing helps to the follow-up study.展开更多
In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Th...In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Three different coupling methods have been used in order to investigate the mode interaction between the two Turing modes. It is proved in the simulations that interaction between activators in the two sub-systems leads to spontaneous formation of black eye pattern and/or white eye patterns while interaction between inhibitors leads to spontaneous formation of super-hexagonal pattern. It is also demonstrated that the same symmetries of the two modes and suitable wavelength ratio of the two modes should also be satisfied to form superlattice patterns.展开更多
A triad mode resonance, or three-wave resonance, is typical of dynamical systems with quadratic nonlinearities. Suspended cables are found to be rich in triad mode resonant dynamics. In this paper, modulation equation...A triad mode resonance, or three-wave resonance, is typical of dynamical systems with quadratic nonlinearities. Suspended cables are found to be rich in triad mode resonant dynamics. In this paper, modulation equations for cable's triad resonance are formulated by the multiple scale method. Dynamic conservative quantities, i.e., mode energy and Manley-Rowe relations, are then constructed. Equilibrium/dynamic solutions of the modulation equations are obtained, and full investigations into their stability and bifurcation characteristics are presented. Various bifurcation behaviors are detected in cable's triad resonant responses, such as saddle-node, Hopf, pitchfork and period-doubling bifurcations. Nonlinear behaviors, like jump and saturation phenomena, are also found in cable's responses. Based upon the bifurcation analysis, two interesting properties associated with activation of cable's triad resonance are also proposed, i.e., energy barrier and directional dependence. The first gives the critical amplitude of high-frequency mode to activate cable's triad resonance, and the second characterizes the degree of difficulty for activating cable's triad resonance in two opposite directions, i.e., with positive or negative internal detuning parameter.展开更多
This paper proposes a modified centralized shifted Rayleigh filter（MCSRF） algorithm for tracking boost phase of ballistic missile（BM） trajectory with a highly nonlinear dynamical model based on bearings-only.This ...This paper proposes a modified centralized shifted Rayleigh filter（MCSRF） algorithm for tracking boost phase of ballistic missile（BM） trajectory with a highly nonlinear dynamical model based on bearings-only.This paper contributes three folds.Firstly,the mathematical model of an MCSRF for multiple passive sensors is derived.Then,minimum entropy based onedimensional optimization search to adaptively adjust the probability of the different filters for real time state estimation is deployed.Finally,the unscented transform（UT） is introduced to resolve the asymmetric state estimation problem.Simulation results show that the proposed algorithm can consecutively track the BM precisely during the boost phase.In comparison with the unscented Kalman filter（UKF） algorithm,the proposed algorithm effectively reduces the tracking position and velocity root mean square（RMS） errors,which will make more sense for early precision interception.展开更多
Developing a comprehensive understanding of inter-city interactions is crucial for regional planning.We therefore examined spatiotemporal patterns of population migration across the Qinghai-Tibet Plateau(QTP)using mig...Developing a comprehensive understanding of inter-city interactions is crucial for regional planning.We therefore examined spatiotemporal patterns of population migration across the Qinghai-Tibet Plateau(QTP)using migration big data from Tencent for the period between 2015 and 2019.We initially used decomposition and breakpoint detection methods to examine time-series migration data and to identify the two seasons with the strongest and weakest population migration levels,between June 18th and August 18th and between October 8th and February 15th,respectively.Population migration within the former period was 2.03 times that seen in the latter.We then used a variety of network analysis methods to examine population flow directions as well as the importance of each individual city in migration.The two capital cities on the QTP,Lhasa and Xining,form centers for population migration and are also transfer hubs through which migrants from other cities off the plateau enter and leave this region.Data show that these two cities contribute more than 35%of total population migration.The majority of migrants tend to move within the province,particularly during the weakest migration season.We also utilized interactive relationship force and radiation models to examine the interaction strength and the radiating energy of each individual city.Results show that Lhasa and Xining exhibit the strongest interactions with other cities and have the largest radiating energies.Indeed,the radiating energy of the QTP cities correlates with their gross domestic product(GDP)(Pearson correlation coefficient:0.754 in the weakest migration season,WMS versus 0.737 in the strongest migration season,SMS),while changes in radiating energy correlate with the tourism-related revenue(Pearson correlation coefficient:0.685).These outcomes suggest that level of economic development and level of tourism are the two most important factors driving the QTP population migration.The results of this analysis provide critical clarification guidance regarding huge QTP development differences.展开更多
Hydraulic fracturing is considered the main stimulation method to develop shale gas reservoirs. Due to its strong heterogeneity, the shale gas formation is typically embedded with geological discontinuities such as be...Hydraulic fracturing is considered the main stimulation method to develop shale gas reservoirs. Due to its strong heterogeneity, the shale gas formation is typically embedded with geological discontinuities such as bedding planes and natural fractures. Many researchers realized that the interaction between natural fractures and hydraulic fractures plays a crucial role in generating a complex fracture network. In this paper, true tri-axial hydraulic fracturing tests were performed on polymethyl methacrylate (PMMA), on which pre-existing fracture was pre-manufactured to simulate natural fracture. A cohesive model has been developed to verify the results of the experimental tests. The key findings demonstrate that the experimental results agreed well with the numerical simulation outcomes where three main interaction modes were observed: crossing;being arrested by opening the pre-existing fracture;being arrested without dilating the pre-existing fracture. Crossing behavior is more likely to occur with the approaching angle, horizontal stress difference, and injection rate increase. Furthermore, the higher flow rate might assist in reactivating the natural fractures where both sides of the pre-existing fractures were reactivated as the injection rate increased from 5 to 20 mL/min. Additionally, hydraulic fractures show a tendency to extend vertically rather than along the direction of maximum horizontal stress when they are first terminated at the interface. This research may contribute to the field application of hydraulic fracturing in shale gas formation.展开更多
To investigate higher harmonics induced by a submerged obstacle in the presence of uniform current, a 2D fully nonlinear numerical wave flume（NWF） is developed by use of a time-domain higher-order boundary element m...To investigate higher harmonics induced by a submerged obstacle in the presence of uniform current, a 2D fully nonlinear numerical wave flume（NWF） is developed by use of a time-domain higher-order boundary element method（HOBEM） based on potential flow theory. A four-point method is developed to decompose higher bound and free harmonic waves propagating upstream and downstream around the obstacle. The model predictions are in good agreement with the experimental data for free harmonics induced by a submerged horizontal cylinder in the absence of currents. This serves as a benchmark to reveal the current effects on higher harmonic waves. The peak value of non-dimensional second free harmonic amplitude is shifted upstream for the opposing current relative to that for zero current with the variation of current-free incident wave amplitude, and it is vice versa for the following current. The second-order analysis shows a resonant behavior which is related to the ratio of the cylinder diameter to the second bound mode wavelength over the cylinder. The second-order resonant position slightly downshifted for the opposing current and upshifted for the following current.展开更多
Two novel mixed-ligand complexes, [M（phen）2（ans）2]·H2O （M = Cd（Ⅱ） 1, Zn（Ⅱ） 2; phen is 1, 10-phenanthroline, and ans is 4-aminonaphthalene-1-sulfonate）, were obtained from the reaction of 1, 10-phenant...Two novel mixed-ligand complexes, [M（phen）2（ans）2]·H2O （M = Cd（Ⅱ） 1, Zn（Ⅱ） 2; phen is 1, 10-phenanthroline, and ans is 4-aminonaphthalene-1-sulfonate）, were obtained from the reaction of 1, 10-phenanthroline, sodium 4-aminonaphthalene-1-sulfonate tetrahydrate and acetate in mixed solvents. Interaction of the complexes with calf thymus DNA （ctDNA） were investigated using UV-vis absorption spectra, luminescence titrations, steady-state emission quenching by [Fe（CN）6]4 , DNA competitive binding with ethidium bromide （EB） and viscosity measurements. The experimental results indicate that there exist two interaction modes between the complexes and DNA, namely the electrostatic interaction and intercalation, with the binding constants of 1.82 × 10^5 M-1 for 1 and 4.78 ×10^4 M^- 1 for 2 in buffer of 50 mM NaCl and 5 mM Tris-HCI （pH 7.0）.展开更多
CONSPECTUS:Metamaterials operating at infrared(IR)frequencies have garnered significant attention due to the opportunities for resonant interactions with vibrational modes of molecules and materials and manipulation o...CONSPECTUS:Metamaterials operating at infrared(IR)frequencies have garnered significant attention due to the opportunities for resonant interactions with vibrational modes of molecules and materials and manipulation of thermal emission.These metamaterials usually consist of periodic arrangements of subwavelength scale metallic or dielectric elements,patterned either top-down by nanolithographic methods or bottom-up by nanocrystal(NC)assembly.However,conventional metals are inherently constrained by their fixed electron concentrations,which limits the degrees of freedom in the design of the metaatom unit cells to achieve the desired optical response.In this context,doped metal oxide NCs,with the prototypical case being tin-doped indium oxide(ITO)NCs,are exceptional candidates for self-assembled IR metamaterials,owing to their relatively low and synthetically tunable electron concentrations that govern the frequencies of their IR plasmon resonances.Focusing on ITO NCs as building blocks,this Account describes recent progress in the synthetic tuning of NC optical properties,NC superlattice monolayer preparation methods for fabricating IR resonant metamaterials,and the emerging understanding of the optical response,facilitated by recently developed simulation methods.Based on experimental and simulation methods we helped develop,we are advancing a mechanistic understanding of how selfassembled NC metamaterials can produce distinctive near-and far-field optical properties not readily achievable in lithographically patterned structures.First,the impacts of the inevitable defects and disorder associated with self-assembly can be rationalized and,in some cases,recognized as advantageous.Second,self-assembly enables intimate nanoscale intermixing of different NC and molecular components.By incorporating probe molecules within the gaps between NCs where the electric field enhancement is the strongest,we show enhanced detection of molecular vibrations that can be optimized by tuning the size and resonance frequency of the NCs.We show how metasurfaces incorporating mixtures of NCs with different doping concentrations can achieve an epsilon-near-zero dielectric response over a broad frequency range.Finally,considering the NC metasurface itself as a building block,we show how photonic structures incorporating these assemblies can harness and amplify their distinctive properties.Through modeling the NC monolayer as a slab with an effective permittivity response,we designed a frequency-tunable IR perfect absorber by layering the NCs on a simple open cavity structure.Since the perfect absorption architecture further enhances the IR electric field localization strength,we expect that this integration strategy can enhance molecular vibration coupling or nonlinear optical response.The versatility of the NC assembly and integration approach suggests opportunities for various metal oxide NC superstructures,including mixing and stacking of NCs beyond a single monolayer,representing a vast parameter space for the design of linear and nonlinear IR optical components.展开更多
文摘We consider a triple zero point of nonlinear equations with O(2 symmetry, where the Jacobian has a zero eigenvalue of geometric multiplicity one and algebraic multiplicity three. We show that this triple zero point exhibits a new bifurcation phenomenon, that is, a mode interaction of the following three paths: bifurcation points from steady states, steady states and rotating waves to standing waves, rotating waves and modulated rotating waves respectively.
文摘In the modern higher education music curriculum system,the teacher-student interaction mode is a key factor affecting the effectiveness of piano teaching.However,the current teacher-student interaction mode in piano teaching still has limitations,such as one-way transmission and a lack of personalized feedback.Based on constructivist learning theory and social interaction theory,combined with information technology,this paper explores the optimization strategy of interaction mode in the piano teaching process of normal universities.This study adopts classroom observation and interview methods to analyze the impact of different interaction modes on students’piano learning effectiveness,learning engagement,and autonomous learning ability.The research results show that the constructivist interactive teaching mode supported by information technology can significantly enhance students’interest in learning and playing skills,optimize the classroom teaching atmosphere,and promote the improvement of their comprehensive literacy.
文摘With the development of globalization,intercultural communicative competence has become one of the core qualities of modern college students.As an important platform to cultivate students’language skills and cultural literacy,the innovation of college English teaching mode is essential.Based on this,this paper mainly discusses methods to effectively cultivate students’intercultural communicative competence in college English teaching from the perspective of multimodal interactive teaching mode,hoping to provide references for improving the quality of college English teaching and students’comprehensive quality.
基金supported by the Program of State Grid Corporation of China“Theoretical BasisAlgorithmand Application of Trajectory Eigenvalue Method”
文摘Complex phenomena such as prolongedly undamped ultra-low frequency oscillation(ULFO)and eigenmode re-excitation are observed in the simulations of hydroelectric power systems.Emphases are put on nonlinearities and mode interactions,which cannot be analyzed by traditional eigen-analysis methods.In order to investigate the mechanism of the evolvement of the nonlinear dynamic process in ULFO,this paper proposes a method to analyze the mode interactions quantificationally.First,a disturbed trajectory is decoupled into a set of time-varying components.Second,transfer matrices of eigenmodes are extracted along the trajectory.Third,consecutive sequences of eigenvalues and trajectories of components are formed by a proposed technique.Based on the decoupled components and transfer matrices,the mechanisms of mode interactions and inheritance relationships between eigenmodes are analyzed.The causes and developments of the above complex phenomena are revealed by the proposed method in a test two-machine system.Meanwhile,the accuracy of the eigenmode matching technique is verified in the New England system.
基金Project supported by the National Natural Science Foundation of China(Nos.91741113,91841303,and 91941301)。
文摘The underlying effect of vortex interaction characterized by the merging and non-merging on mixing enhancement is of fundamental significance to understand the flow dynamics of strut injectors in scramjets.Starting from a simplified configuration of a vortex generator,this study focuses on the influence of geometric parameters on vortex structures and fluid mixing through compressible Navier-Stokes(NS)simulations.By adjusting the induction of outer vortices,the inner co-rotating vortex pair exhibits two modes of interaction(merging/separation regime)reflected by closer/farther vortex centers.Defined by the zero variation rate of the inner vortex spacing,the critical state of equilibrium is determined.The critical condition is well predicted by a theoretical model based on the Biot-Savart law.Through the introduction of mixedness and mixing time,the intrinsic impact of interaction modes on fluid mixing is revealed.Compared with the vortex dynamics in the merging regime,the one in the separation regime is more effective for passive scalar mixing augmentation.With efficient material stretching characterized by the higher interface stretching factor and averaging finite-time Lyapunov exponent(FTLE),the mixing time is shortened by as much as 2.5 times in the separation regime.The implication of the present two interaction regimes in mixing enhancement physically reflected by the averaging FTLE has the potential to improve the combustion performance and shorten the combustor chamber.
基金the Major State Basic Research Development Program of China(973 Program)(Grant No.2002CB312002)the National Natural Science Foundation of China(Grant No.60403014)Nature Science Foundation of Jiangsu Province Project(Grant No.BK2006712)
文摘Due to the independency, variability, and tailorability of software service in the open environment, the research of middleware which supports software services multi-mode interaction is thus of great importance. In this paper, an agent-based multi-mode interaction middleware model and its supporting system for software services were proposed. This model includes an interaction feature decomposition and configuration model to enable interaction programming, an agent-based middleware model, and a programmable coordination media based on reflection technology. The decomposition and configuration model for interaction features can assist programmers in interaction programming by analyzing and synthesizing interaction features. The agent-based middleware model provides a runtime framework for service multi-mode interaction. The programmable coordination media is able to effectively support software service coordination based on multimode interaction. To verify feasibility and efficiency of the above method, the design, implementation and performance analysis of Artemis-M3C, a multi-mode interaction middleware for software services, were introduced. The result shows that the above method is feasible and that the Artemis-M3C system is practical and effective in multi-mode interaction.
基金Supported by the National Natural Science Foundation of China under Grant No 11274379the Research Funds of Renmin University of China under Grant No 14XNLQ07
文摘The one-dimensional interacting Kitaev chain at half filling is studied. The symmetry of the Hamiltonian is examined by dual transformations, and various physical quantities as a function of the fermion-fermion interaction U are calculated systematically using the density matrix renormalization group method. A special value of interaction Up is revealed in the topological region of the phase diagram. We show that at Up the ground states are strictly two-fold degenerate even though the chain length is finite and the zero-energy peak due to the Majorana zero modes is maximally enhanced and exactly localized at the end sites. Here Up may be attractive or repulsive depending on other system parameters. We also give a qualitative understanding of the effect of interaction under the self-consistent mean field framework.
基金Project supported by the National Natural Science Foundation of China(No.11332007)
文摘Nonlinear interactions of the two-dimensional （2D） second mode with oblique modes are studied numerically in a Mach 6.0 fiat-plate boundary layer, focusing on its selective enhancement effect on amplification of different oblique waves. Evolution of oblique modes with various frequencies and spanwise wavenumbers in the presence of 2D second mode is simulated successively, using a modified parabolized stability equation （PSE） method, which is able to simulate interaction of two modes with different frequen- cies efficiently. Numerical results show that oblique modes in a broad band of frequencies and spanwise wavenumbers can be enhanced by the finite amplitude 2D second mode instability wave. The enhancement effect is accomplished by interaction of the 2D second mode, the oblique mode, and a forced mode with difference frequency. Two types of oblique modes are found to be more amplified, i.e., oblique modes with frequency close to that of the 2D second mode and low-frequency first mode oblique waves. Each of them may correspond to one type of transition routes found in transition experiments. The spanwise wavenumber of the oblique wave preferred by the nonlinear interaction is also determined by numerical simulations.
基金This work was supported by the N N S F of China (No. 20471026)the Natural Science Foundation of Henan Province (No. 0311021200)
文摘A new copper（Ⅱ） compound with imino nitroxide radicals [Cu（IM-MeImz）2].（SCN）2 （IM-meImz =2-（5-methylimidazol-4-yl）-4,4,5,5-tetramethyl-2-imidazoline- 1-oxyl） has been synthesized and characterized structurally and magnetically. It crystallizes in monoclinic, space group P21/c with a = 9.3604（7）, b = 10.3012（7）, c = 16.6684（12）A, β = 105.0290（10）^o, V = 1552.25（19）A3, C24H34CUN10O2S2, Mr = 622.27, Z = 2, Dc = 1.331 g/cm^3,μ（MoKα） = 0.876 mm^-1, F（000） = 650, the final R = 0.0374 and wR = 0.1079. X-ray analysis demonstrates that the IM-MeImz ligand is coordinated to the copper（Ⅱ） ion as an unusual didentate chelate with a k-2 N（MeImz）,O（IM） mode in the complex. The square-planar coordination sites at Cu（Ⅱ） are occupied by two 0 and two N atoms from the imino nitroxide radicals. The complex molecules are connected as a onedimensional polymer structure by intermolecular interactions. Magnetic measurements show that there are intramolecular antiferromagnetic interactions between the Cu（Ⅱ） ion and radicals.
基金supported by a National Natural Science Foundation of China NSFC project (Grant No. 41405086)the strategic priority research program grant of the Chinese Academy of Sciences (Grant No. XDA19070402)the NSFC projects (41775090, 41705049)
文摘The variability in the Southern Ocean（SO） sea surface temperature（SST） has drawn increased attention due to its unique physical features; therefore, the temporal characteristics of the SO SST anomalies（SSTA） and their influence on extratropical atmospheric circulation are addressed in this study. Results from empirical orthogonal function analysis show that the principal mode of the SO SSTA exhibits a dipole-like structure, suggesting a negative correlation between the SSTA in the middle and high latitudes, which is referred to as the SO Dipole（SOD） in this study. The SOD features strong zonal symmetry, and could reflect more than 50% of total zonal-mean SSTA variability. We find that stronger（weaker） Subantarctic and Antarctic polar fronts are related to the positive（negative） phases of the SOD index, as well as the primary variability of the large-scale SO SSTA meridional gradient. During December–January–February, the Ferrel cell and the polar jet shift toward the Antarctic due to changes in the SSTA that could be associated with a positive phase of the SOD, and are also accompanied by a poleward shift of the subtropical jet. During June–July–August, in association with a positive SOD, the Ferrel cell and the polar jet are strengthened, accompanied by a strengthened subtropical jet. These seasonal differences are linked to the differences in the configuration of the polar jet and the subtropical jet in the Southern Hemisphere.
文摘The college students are the main force of contemporary youth, their involvement in the ideological and political course of study is very favorable on their personal development. But affected by the traditional education ideas, in colleges there are many deficiencies appeared in the process of ideological and political education, which have restricted the promotion of college students＇ Ideological and political awareness. This paper firstly analyzes the deficiencies of the traditional ideological and political education, discusses the key points of creating the intemet interactive mode, and puts forward the creative decision on ideological and political education based on the internet interactive mode, in hopes of providing helps to the follow-up study.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10975043, 10947166 and 10775037the Foundation of Bureau of Education, Hebei Province, China under Grant No. 2009108the Natural Science Foundation of Hebei Province, China under Grant No. A2008000564)
文摘In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Three different coupling methods have been used in order to investigate the mode interaction between the two Turing modes. It is proved in the simulations that interaction between activators in the two sub-systems leads to spontaneous formation of black eye pattern and/or white eye patterns while interaction between inhibitors leads to spontaneous formation of super-hexagonal pattern. It is also demonstrated that the same symmetries of the two modes and suitable wavelength ratio of the two modes should also be satisfied to form superlattice patterns.
基金Supporting Program for Young Investigators,Hunan UniversityNational Science Foundation of China(Grant Nos.11502076 and 11572117)
文摘A triad mode resonance, or three-wave resonance, is typical of dynamical systems with quadratic nonlinearities. Suspended cables are found to be rich in triad mode resonant dynamics. In this paper, modulation equations for cable's triad resonance are formulated by the multiple scale method. Dynamic conservative quantities, i.e., mode energy and Manley-Rowe relations, are then constructed. Equilibrium/dynamic solutions of the modulation equations are obtained, and full investigations into their stability and bifurcation characteristics are presented. Various bifurcation behaviors are detected in cable's triad resonant responses, such as saddle-node, Hopf, pitchfork and period-doubling bifurcations. Nonlinear behaviors, like jump and saturation phenomena, are also found in cable's responses. Based upon the bifurcation analysis, two interesting properties associated with activation of cable's triad resonance are also proposed, i.e., energy barrier and directional dependence. The first gives the critical amplitude of high-frequency mode to activate cable's triad resonance, and the second characterizes the degree of difficulty for activating cable's triad resonance in two opposite directions, i.e., with positive or negative internal detuning parameter.
基金supported by the Aerospace Science and Technology Innovation Foundation (CASC0202-3)
文摘This paper proposes a modified centralized shifted Rayleigh filter（MCSRF） algorithm for tracking boost phase of ballistic missile（BM） trajectory with a highly nonlinear dynamical model based on bearings-only.This paper contributes three folds.Firstly,the mathematical model of an MCSRF for multiple passive sensors is derived.Then,minimum entropy based onedimensional optimization search to adaptively adjust the probability of the different filters for real time state estimation is deployed.Finally,the unscented transform（UT） is introduced to resolve the asymmetric state estimation problem.Simulation results show that the proposed algorithm can consecutively track the BM precisely during the boost phase.In comparison with the unscented Kalman filter（UKF） algorithm,the proposed algorithm effectively reduces the tracking position and velocity root mean square（RMS） errors,which will make more sense for early precision interception.
基金National Natural Science Foundation of China(41590845)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA19040501)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20040401)National Key Research and Development Program of China(2017YFB0503605)National Key Research and Development Program of China(2017YFC1503003)。
文摘Developing a comprehensive understanding of inter-city interactions is crucial for regional planning.We therefore examined spatiotemporal patterns of population migration across the Qinghai-Tibet Plateau(QTP)using migration big data from Tencent for the period between 2015 and 2019.We initially used decomposition and breakpoint detection methods to examine time-series migration data and to identify the two seasons with the strongest and weakest population migration levels,between June 18th and August 18th and between October 8th and February 15th,respectively.Population migration within the former period was 2.03 times that seen in the latter.We then used a variety of network analysis methods to examine population flow directions as well as the importance of each individual city in migration.The two capital cities on the QTP,Lhasa and Xining,form centers for population migration and are also transfer hubs through which migrants from other cities off the plateau enter and leave this region.Data show that these two cities contribute more than 35%of total population migration.The majority of migrants tend to move within the province,particularly during the weakest migration season.We also utilized interactive relationship force and radiation models to examine the interaction strength and the radiating energy of each individual city.Results show that Lhasa and Xining exhibit the strongest interactions with other cities and have the largest radiating energies.Indeed,the radiating energy of the QTP cities correlates with their gross domestic product(GDP)(Pearson correlation coefficient:0.754 in the weakest migration season,WMS versus 0.737 in the strongest migration season,SMS),while changes in radiating energy correlate with the tourism-related revenue(Pearson correlation coefficient:0.685).These outcomes suggest that level of economic development and level of tourism are the two most important factors driving the QTP population migration.The results of this analysis provide critical clarification guidance regarding huge QTP development differences.
基金support from Major Program of the National Natural Science Foundation of China(Grant No.52192621)the National Natural Science Foundation of China for Major International(Regional)Joint Research Project(Grant No.52020105001)+1 种基金Major Science and Technology Project of Yunnan Province(Grant No.202302AF080001)Beijing Outstanding Young Scientist Program(Grant No.BJJWZYJH01201911414038).
文摘Hydraulic fracturing is considered the main stimulation method to develop shale gas reservoirs. Due to its strong heterogeneity, the shale gas formation is typically embedded with geological discontinuities such as bedding planes and natural fractures. Many researchers realized that the interaction between natural fractures and hydraulic fractures plays a crucial role in generating a complex fracture network. In this paper, true tri-axial hydraulic fracturing tests were performed on polymethyl methacrylate (PMMA), on which pre-existing fracture was pre-manufactured to simulate natural fracture. A cohesive model has been developed to verify the results of the experimental tests. The key findings demonstrate that the experimental results agreed well with the numerical simulation outcomes where three main interaction modes were observed: crossing;being arrested by opening the pre-existing fracture;being arrested without dilating the pre-existing fracture. Crossing behavior is more likely to occur with the approaching angle, horizontal stress difference, and injection rate increase. Furthermore, the higher flow rate might assist in reactivating the natural fractures where both sides of the pre-existing fractures were reactivated as the injection rate increased from 5 to 20 mL/min. Additionally, hydraulic fractures show a tendency to extend vertically rather than along the direction of maximum horizontal stress when they are first terminated at the interface. This research may contribute to the field application of hydraulic fracturing in shale gas formation.
基金supported by the National Natural Science Foundation of China(Grant Nos.51179028,51222902,and 51221961)the National Basic Research Program of China(973 Program,Grant No.2011CB013703)+1 种基金the Program for New Century Excellent Talents in University(Grant No.NCET-13-0076)the Fundamental Research Funds for the Central Universities(Grant No.DUT13YQ104)
文摘To investigate higher harmonics induced by a submerged obstacle in the presence of uniform current, a 2D fully nonlinear numerical wave flume（NWF） is developed by use of a time-domain higher-order boundary element method（HOBEM） based on potential flow theory. A four-point method is developed to decompose higher bound and free harmonic waves propagating upstream and downstream around the obstacle. The model predictions are in good agreement with the experimental data for free harmonics induced by a submerged horizontal cylinder in the absence of currents. This serves as a benchmark to reveal the current effects on higher harmonic waves. The peak value of non-dimensional second free harmonic amplitude is shifted upstream for the opposing current relative to that for zero current with the variation of current-free incident wave amplitude, and it is vice versa for the following current. The second-order analysis shows a resonant behavior which is related to the ratio of the cylinder diameter to the second bound mode wavelength over the cylinder. The second-order resonant position slightly downshifted for the opposing current and upshifted for the following current.
基金Funded by Key Project of the National Natural Science Foundation of China (No. 60537050)
文摘Two novel mixed-ligand complexes, [M（phen）2（ans）2]·H2O （M = Cd（Ⅱ） 1, Zn（Ⅱ） 2; phen is 1, 10-phenanthroline, and ans is 4-aminonaphthalene-1-sulfonate）, were obtained from the reaction of 1, 10-phenanthroline, sodium 4-aminonaphthalene-1-sulfonate tetrahydrate and acetate in mixed solvents. Interaction of the complexes with calf thymus DNA （ctDNA） were investigated using UV-vis absorption spectra, luminescence titrations, steady-state emission quenching by [Fe（CN）6]4 , DNA competitive binding with ethidium bromide （EB） and viscosity measurements. The experimental results indicate that there exist two interaction modes between the complexes and DNA, namely the electrostatic interaction and intercalation, with the binding constants of 1.82 × 10^5 M-1 for 1 and 4.78 ×10^4 M^- 1 for 2 in buffer of 50 mM NaCl and 5 mM Tris-HCI （pH 7.0）.
基金primarily supported by the National Science Foundation through the Center for Dynamics and Control of Materials:an NSF MRSEC under Cooperative Agreement Nos.DMR-1720595 and DMR-2308817support from the Welch Foundation(F-1696 and F-1848)+1 种基金support from the Defense Advanced Research Projects Agency(DARPA)under the Optomechanical Thermal Imaging(OpTIm)program(HR00112320022)the Multidisciplinary University Research Initiative of the Air Force Office of Scientific Research(AFOSR MURI Award No.FA9550-22-1-0307).
文摘CONSPECTUS:Metamaterials operating at infrared(IR)frequencies have garnered significant attention due to the opportunities for resonant interactions with vibrational modes of molecules and materials and manipulation of thermal emission.These metamaterials usually consist of periodic arrangements of subwavelength scale metallic or dielectric elements,patterned either top-down by nanolithographic methods or bottom-up by nanocrystal(NC)assembly.However,conventional metals are inherently constrained by their fixed electron concentrations,which limits the degrees of freedom in the design of the metaatom unit cells to achieve the desired optical response.In this context,doped metal oxide NCs,with the prototypical case being tin-doped indium oxide(ITO)NCs,are exceptional candidates for self-assembled IR metamaterials,owing to their relatively low and synthetically tunable electron concentrations that govern the frequencies of their IR plasmon resonances.Focusing on ITO NCs as building blocks,this Account describes recent progress in the synthetic tuning of NC optical properties,NC superlattice monolayer preparation methods for fabricating IR resonant metamaterials,and the emerging understanding of the optical response,facilitated by recently developed simulation methods.Based on experimental and simulation methods we helped develop,we are advancing a mechanistic understanding of how selfassembled NC metamaterials can produce distinctive near-and far-field optical properties not readily achievable in lithographically patterned structures.First,the impacts of the inevitable defects and disorder associated with self-assembly can be rationalized and,in some cases,recognized as advantageous.Second,self-assembly enables intimate nanoscale intermixing of different NC and molecular components.By incorporating probe molecules within the gaps between NCs where the electric field enhancement is the strongest,we show enhanced detection of molecular vibrations that can be optimized by tuning the size and resonance frequency of the NCs.We show how metasurfaces incorporating mixtures of NCs with different doping concentrations can achieve an epsilon-near-zero dielectric response over a broad frequency range.Finally,considering the NC metasurface itself as a building block,we show how photonic structures incorporating these assemblies can harness and amplify their distinctive properties.Through modeling the NC monolayer as a slab with an effective permittivity response,we designed a frequency-tunable IR perfect absorber by layering the NCs on a simple open cavity structure.Since the perfect absorption architecture further enhances the IR electric field localization strength,we expect that this integration strategy can enhance molecular vibration coupling or nonlinear optical response.The versatility of the NC assembly and integration approach suggests opportunities for various metal oxide NC superstructures,including mixing and stacking of NCs beyond a single monolayer,representing a vast parameter space for the design of linear and nonlinear IR optical components.
