The existence and uniqueness of positive solutions for a class of nth order m point boundary value problem is studied by using the mixed monotone operators and fixed-point theorem;moreover an it-erative sequence is constructed to approximate this positive solution.
The system of three-level atom interacting with light field is studied by using the method of full quantum theory.Based on wave function,the dynamic evolution characteristics of different quantum states with the same coupling intensity are studied.In addition,the influence of different coupling intensi-ty of the same quantum state on the dynamic evolution characteristics of the system is discussed.The re-sults show that under the same coupling intensity,the population values of atoms in |b1＞states first de-crease and then increase with time,the population values of atoms in b2＞states and |b3＞states first in-crease and then decrease with time,and the corresponding population values of |b2＞states produce three peaks in the same period.The population values corresponding to the | b3＞states produce two peaks in the same period,and there is also a trough after the first peak,and the population values of different quantum states show periodic oscillations with time.In the same quantum state,with the increase of the coupling coefficient,the dynamic evolution oscillation characteristics of the quantum state between the light field and atoms are enhanced,and the system dynamic evolution pattern always maintains periodic changes with the increase of time.
Acoustically transmissive cloak is constructed with a combination of two labyrinthine type metasurfaces-phase-modulated metasurface and near-zero refractive index metasurface.The near-zero re-fractive index metasurface is verified by energy band calculation and equivalent medium theory to have zero refractive index property similar to phonon crystals,so that it can guide the acoustic waves to contin-ue to go around the obstacles in the original direction of the acoustic waves;the phase-modulated meta-surface,on the other hand,should have a high transmittance while having the role of phase-modulation to ensure that the acoustic waves can pass through in large quantities.The simulations and calculations show that the acoustic transmission cloak formed by the construction works well.
The method of using OF-DFT to study the ground-state density and work function of metal so-dium plates was explored.Through extensive numerical experiments,it was determined that a vW kinetic energy functional weight of 0.4 is required to obtain accurate ground-state properties for metal sodium plates,and this kinetic energy functional weight is applicable to different exchange-correlation potentials.
Based on the low-energy effective hamiltonian model under the tight-binding approximation,the modulation of the electronic band structure of weyl semimetals by applied electric and/or magnetic fields is investigated.The results show that:when only the positive(negative)electric field is applied,the weyl points of system gradually move towards the boundary(center)of the brillouin zone with the increasing of the electric field strength,and when the electric field strength increases to a certain extent,the semi-metal-semiconductor(insulator)transition can be relieazed;when only the magnetic field is applied,the weyl semimetal can form the discrete landau levels,the n=0 subband does not change with the increasing of magnetic length while the n≠0 subband gradually approaches the fermi level with the increasing of magnetic length,and the band gap between the conduction and valence bands with same indices gradually decrease;when the magnetic length remains unchanged,the weyl points of system gradually move to-wards the boundary(center)of the brillouin zone with the increasing of the positive(negative)electric field strength.Under the appropriate electric field,the n=0 subband can change from partially occupied valence band to first conduction band(fully occupied first valence band)and realize the semimetal-semi-conductor or semimetal-insulator transitions.
By normalizing the sample skewness and kurtosis of the received signal,a spectrum sensing al-gorithm based on joint detection of skewness and kurtosis(joint detection)is proposed.Utilizing the probability density function of the chi-square distribution,the theoretical false alarm performance of the algorithm is analyzed under non-asymptotic conditions,and the corresponding theoretical decision thresh-old is derived.In the simulation experiments,joint detection can still guarantee reliable detection results with small number of samples,and shows better detection performance than the classical Jarque-Bera(JB)spectrum sensing algorithm.
A video image pixel compensation method based on local convolution(local convolution com-pensation)is proposed to repair missing pixels in high-speed moving targets.The method introduces local convolution to segment the neural network model and reconstruct video image frames.It activates the source video image and its corresponding pixel space,applies linear mean compensation to fill the interpo-lated frame holes in the video image,and evaluates the matching degree of the video image to complete the pixel compensation.Comparative experimental results show that the average gradient of the local convolution compensation method is 11.239,significantly higher than the other three comparative meth-ods,which indicates that the video image after compensation using the local convolution method has higher clarity.
Based on density functional theory combined with non-equilibrium Greens function,the voltam-metric properties of transition metal Cu-Cr,Cu-V and Cu-Ti co-doped CdTe nanoelectronic devices were systematically investigated.The results show that the voltammetric curves of the three different co-doped CdTe nanodevices exhibit diode voltammetric curves and produce strong rectification effects in the bias voltage range of[+0.4 V,+0.8 V].The highest rectification ratios are 5.4 X 104,3.8 × 105,and 2.1X106,respectively.The projected density of states further confirms the high rectification ratio of the device at+1.0 V bias.Under the Cu-Cr co-doping condition,the device current decreases somewhat at+0.9 V bias with increasing channel length in the center region,but the overall rectification performance is significantly improved in the[+0.5 V,+0.7 V]bias range.
In order to solve the problem of low precision and original network information lose in commu-nity detection of bipartite network,a new spectral clustering algorithm named SVD-MS is proposed.This method maps Barber's problem of maximizing the module size of bipartite networks to the problem of singular value vector decomposition,and combines heuristic algorithms to quickly solve vector partitio-ning problems.Experimental results show that,the SVD-MS algorithm can effectively partition the com-munity structure of bipartite networks and preserve the original network information.
Based on the method of Green's function presolvation operator,the spontaneous radiation dy-namics of V-type three-level atoms near silver nanospheres are studied.The effects of atomic transition frequency and atomic distance on the surface of the nanosphere on the spontaneous radiation dynamics are investigated systematically.The results show that when the transition frequency of the atom is far a-way from the resonant frequency of the isoplasmon,the evolution spectrum of the atom is half high and narrow,the dynamic oscillation is enhanced,and the decay rate is slow with time.When the two transi-tion frequencies are close to the formant frequency,the kinetic oscillation of the atom is weakened,and the attenuation rate is faster with time.The distance between the atom and the surface of the nanosphere plays an important role in the coherent oscillation.The closer the distance,the stronger the coherent os-cillation;and the farther the distance,the weaker the coherent oscillation.
Based on the quasi-normal mode(QNM)theory,in the local photoresponse model,fluid dynam-ics model and generalized non-local photoresponse model of free electrons in metals,the spontaneous e-mission enhancement characteristics of two-level atoms in the nano-column structure are studied.With efficient coupled QNM theory,the effects of quantum dot position and double-column gap distance on the enhancement properties of spontaneous emission are investigated.The results show that compared with the full-wave method,the quasi-canonical mode method can efficiently and accurately calculate the en-hanced characteristics of spontaneous emission,and the nanopillar gap has an important influence on the resonance frequency of the quasi-canonical mode.These studies have important guiding significance for understanding the nanoscale dimer structure to enhance light-matter interaction.
The influence of the transition frequency and position of a two-level atom in the vicinity the convex structure on the resonant casimir-polder force is studied by using COMSOL Multiphysics soft-ware.The results show that compared with the cross-sectional silver nanospheres,the convex structure produces a new surface plasmon resonance mode,which greatly enhances the resonance casimir-polder force on the atom.In addition,when the atom is close to the surface of the convex structure,the new res-onance mode plays a leading role in the regulation of the resonant casimir-polder force,and the contribu-tion of the new resonant mode to the resonant casimir-polder force decreases sharply with the increase of the distance.and the contribution of the resonance mode produced by the bulge is faster than that pro-duced by the cross-section silver nanospheres.
A tunable dual-frequency perfect absorber consisting of a graphene resonator,a SiO2 dielectric layer and a metal reflector layer has been designed by utilizing the excellent tunable optical properties of graphene.The effects of graphene chemical potential,polarization angle and size on the absorber absorp-tion performance were systematically investigated,and the electric field pattern at the resonance frequen-cy was analyzed to further explain the principle of absorber absorption.The results show that the absorb-er has an absorption rate of 99.98％and 99.99％at 6.363 and 8.987,respectively.The absorption peak position of the absorber can be effectively adjusted by changing the chemical potential of graphene,and the peak absorption rate can reach more than the peak absorption rate at any polarization angle in the range of 0°～80°.The thickness of the SiO2 dielectric layer has almost no effect on the resonance peak po-sition of this absorber,but it has some effect on the peak absorption rate,which increases and then de-creases with the gradual increase of the thickness,and perfect absorption is achieved near the thickness of 3.1 µm.The high absorption rate of this absorber stems mainly from the electromagnetic resonance effect.
The fast Fourier transform(FFT)method may encounter spectral leakage and picket fence effect in harmonic detection,resulting in low accuracy in detecting harmonic and inter-harmonic parame-ters.To improve the detection accuracy,based on the maximum side lobe decay window(MSLD)with excellent sidelobe characteristics,we have constructe an MSLD self-multiplication-convolution window(MSLDSMC)by multiplication and convolution operations.On this basis we propos a high-precision esti-mation algorithm for harmonic and inter-harmonic parameters of three spectral line interpolation.Simula-tion experiments conducted in different complex scenarios verify the accuracy of harmonic and inter-har-monic parameter estimation algorithms based on MSLDSMC window three spectral line interpolation.
The trapping mechanism of microbubbles is analyzed based on microbubble acoustic radiation force theory and numerical simulation,and the acoustic radiation force of microbubbles in microcavities is studied.The theoretical analysis showed that when the driving frequency of the sound field is lower than the resonant frequency of the microbubble,the force direction of the microbubble points to the maximum value of the sound field.When the driving frequency of the sound field is higher than the resonant fre-quency of the microbubble,the force direction of the microbubble points to the minimum value of the sound field.Combined with finite element simulation of the quartz cavity,it is verified that the resonance properties exhibited by microbubbles of different sizes in the same acoustic field are different.Smaller microbubbles move towards the acoustic field minimum under the action of standing waves,while larger microbubbles move in the opposite direction.
Taking Guanshe Village in Fujian Province as a research case,an evaluation index system for the vulnerability of tourism based ethnic minority characteristic villages was constructed from two lev-els:internal reasons and external influences,using literature review,questionnaire survey,and other methods.The explanatory structure model was used to systematically analyze the impact of each factor on the vulnerability of ethnic minority villages.The results indicate that the changes in traditional cultur-al customs and natural environmental disasters directly affect the vulnerability of tourism oriented ethnic minority villages;The alienation of traditional architectural renewal and the unsustainable investment in construction are indirect impacts;Excessive tourism development is an important aspect of the vulnera-bility of tourism oriented ethnic minority villages;The insufficient awareness of residents'protection and the process of urbanization are the fundamental impacts on the vulnerability of tourism oriented ethnic minority villages.Based on the current development issues and future development needs,this paper pro-poses protection strategies for tourism oriented ethnic minority characteristic villages in the new era from five perspectives:ideological understanding,coordinated development,cultural inheritance,cultural tourism integration,and safety management.
N-propyl-3,4,9,10-perylene terephthalic-3,4-alcohol ester-9,10-bisimide was synthesized under ultrasonic microwave radiation with N-propyl-3,4,9,10-perylene terephthalic acid and alkyl halide,ali-phatic alcohol as solvent.Results showed that this reaction afforded corresponding compound with 65.7％yields.The optimized reaction condition was as follows:700 W of microwave power,60 min of re-action time,90℃of reaction temperature,and 80％of ultrasonic power.
Based on the Krasnoselskii fixed point theorem,existence of positive solutions to two-point boundary value problems for fractional differential equations involving the Caputo-Fabrizio derivative is discussed,and some sufficient conditions are established to ensure the existence of at least one positive solutions to the boundary problem.
In order to find possible key genes related to the synthesis of polysaccharides in Polygonatum,this study explored the correlation between the expression patterns of core genes in leaves and rhizomes of Polygonatum cyrtonema Hua and Polygonatum odoratum(Mill.)Druce in combination with poly-saccharide synthesis pathways from KEGG database using transcriptome data with expression difference and weighted gene co-expression network analysis(WGCNA).Our results indicated that FBA(fructose-bisphosphate aldolase)and GOLS(galactinol synthase)showed a strong correlation in Pearson linear re-gression calculation,which demonstrated that they are possible key genes for polysaccharide synthesis pathway in Polygonatum.
To address the issues of heterogeneous content,high complexity,and inability to recognize con-textual semantics in diabetic patient-patient online health communities,the BERT-embedded BiLSTM-CRF model is used to recognize six types of entities from the text of the diabetic community"Sweet Home":disease,clinical manifestation,medicine,test,body parts,and emotion.The results demonstrate that the model achieved an accuracy rate of 90.8％,a recall rate of 76％,and a F1 value of 82.8％.The BERT-BiLSTM-CRF model has been shown to be useful for recognition and to serve as a benchmark for more personalized health information and services.
