With the acceleration of urbanization,environmental vibration and noise pollution have become increasingly severe,and traditional vibration and noise reduction technologies are insufficient to meet current vibration c...With the acceleration of urbanization,environmental vibration and noise pollution have become increasingly severe,and traditional vibration and noise reduction technologies are insufficient to meet current vibration control requirements.This study,based on locally resonant theory,designed a novel local resonance periodic block(LRPB).Using the plane wave expansion method(PWEM)and the finite element method(FEM),this study investigated the bandgap characteristics,formation mechanisms,and vibration and acoustic performance of an LRPB under different periodic structures and material selection.The vibration reduction and noise reduction performance of LRPB has been validated through the Qingdao metro project.The research results show that the LRPB is superior to other periodic structures in terms of wide bandgap.Furthermore,configuring soft scatterer material,increasing the unit size,enhancing the material filling rate,and adopting a honeycomb arrangement can effectively reduce bandgap frequency.In structural design,non-high symmetry demonstrates greater advantages.In a study of a subway tunnel,the LRPB demonstrated superior vibration and noise mitigation performance compared to wave impeding block(WIB),thereby demonstrating potential for use in the field of vibration and noise reduction with regard to structures.展开更多
Excessive vibration and noise radiation of the track structure can be caused by the operation of high speed trains.Though the track structure is characterized by obvious periodic properties and band gaps,the bandwidth...Excessive vibration and noise radiation of the track structure can be caused by the operation of high speed trains.Though the track structure is characterized by obvious periodic properties and band gaps,the bandwidth is narrow and the elastic wave attenuation capability within the band gap is weak.In order to effectively control the vibration and noise of track structure,the local resonance mechanism is introduced to broaden the band gap and realize wave propagation control.The locally resonant units are attached periodically on the rail,forming a new locally resonant phononic crystal structure.Then the tuning of the elastic wave band gaps of track structure is discussed,and the formation mechanism of the band gap is explicated.The research results show that a new wide and adjustable locally resonant band gap is formed after the resonant units are introduced.The phenomenon of coupling and transition can be observed between the new locally resonant band gap and the original band gap of the periodic track structure with the band gap width reaching the maximum at the coupling position.The broader band gap can be applied for vibration and noise reduction in high speed railway track structure.展开更多
The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural vibration reduction.In this paper,a novel sandwich-like pla...The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural vibration reduction.In this paper,a novel sandwich-like plate model with local resonator to acquire specific low-frequency bandgaps is proposed.The core layer of the present local resonator is composed by the simply supported overhanging beam,linear spring and mass block,and well connected with the upper and lower surface panels.The simply supported overhanging beam is free at right end,and an additional linear spring is added at the left end.The wave equation is established based on the Hamilton principle,and the bending wave bandgap is further obtained.The theoretical results are verified by the COMSOL finite element software.The bandgaps and vibration characteristics of the local resonance sandwich-like plate are studied in detail.The factors which could have effects on the bandgap characteristics,such as the structural damping,mass of vibrator,position of vibrator,bending stiffness of the beam,and the boundary conditions of the sandwich-like plates,are analyzed.The result shows that the stopband is determined by the natural frequency of the resonator,the mass ratio of the resonator,and the surface panel.It shows that the width of bandgap is greatly affected by the damping ratio of the resonator.Finally,it can also be found that the boundary conditions can affect the isolation efficiency.展开更多
In 1982, Professor Fang Guoliang found the "Non full resonance" phenomenon in a tool system while he use the thin-long tool ultrasonically machining deep-small hole. He called it as "local resonance&quo...In 1982, Professor Fang Guoliang found the "Non full resonance" phenomenon in a tool system while he use the thin-long tool ultrasonically machining deep-small hole. He called it as "local resonance". Also this "Non full resonance" phenomenon was discovered in the ultrasonic drilling and the ultrasonic honing system later. To its mechanism, professor Fang thought that the coupling of long-thin tool bar and driving system is weak, so the tool bar can vibrate independently, but the quantitative relation between the coupling factor and diameter ratio is not made certain. Then several theories come forth to interpret it but still haven’t a common conclusion. Through the systematic experimental and theoretical research, this paper reveals that the "local resonance" phenomenon of ultrasonic honing system has the same essence with the "local resonance" phenomenon in deep hole machining system: when the section area ratio of tool bar and driving system is small enough, some resonance frequencies of combined system are close to the resonance frequencies of "fixed-free" state tool bar, the combined system is still resonant. According to the given depth of hole and structure size, we can use the transfer matrix deduced in this paper to design flexible bar and oilstone seat not only satisfying mechanical structure size but also achieving enough magnitude. It greatly simplified the design. This new method can be named as "local resonance" design method for ultrasonic honing system. The experiment, deduction and design method have a certain common meaning to the study and design of other ultrasonic system.展开更多
To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes,a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed.First,an integrated design me...To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes,a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed.First,an integrated design method is proposed for the longitudinal and transverse wave control of fluid-conveying pipes,and a novel periodic structure unit model is constructed for vibration reduction.Based on the bandgap vibration reduction mechanism of the acoustic metamaterial periodic structure,the material parameters,structural parameters,and the arrangement interval of the periodic structure unit are optimized.The finite element method(FEM)is used to predict the vibration transmission characteristics of the fluid-conveying pipe installed with the vibration reduction periodic structure.Then,the wave/spectrum element method(WSEM)and experimental test are used to verify the calculated results above.Lastly,the vibration attenuation characteristics of the structure under different conditions,such as rubber material parameters,mass ring material,and fluid-structure coupling effect,are analyzed.The results show that the structure can produce a complete bandgap of 46 Hz-75 Hz in the low-frequency band below 100 Hz,which can effectively suppress the low broadband vibration of the fluidconveying pipe.In addition,a high damping rubber material is used in the design of the periodic structure unit,which realizes the effective suppression of each formant peak of the pipe,and improves the vibration reduction effect of the fluid-conveying pipe.Meanwhile,the structure has the effect of suppressing both bending vibration and longitudinal vibration,and effectively inhibits the transmission of transverse waves and longitudinal waves in the pipe.The research results provide a reference for the application of acoustic metamaterials in the multi-directional vibration control of fluid-conveying pipes.展开更多
An emerging ZnO/CuInS_(2) S-scheme heterojunction enables the transformation of ZnO,originally limited to ultraviolet light absorption,into a composite with a strong near-infrared response.The charge transfer from the...An emerging ZnO/CuInS_(2) S-scheme heterojunction enables the transformation of ZnO,originally limited to ultraviolet light absorption,into a composite with a strong near-infrared response.The charge transfer from the p-type semiconductor CuInS_(2) to the n-type semiconductor ZnO leads to an increased hole concentration in the CuInS_(2) quantum dots at the heterojunction interface.Consequently,this enhancement not only amplifies the localized surface plasmon resonance effect but also enhances the near-infrared light absorption of CuInS_(2) quantum dots.This strategy effectively addresses common light response challenges,advancing the overarching objective of utilizing the full solar spectrum.展开更多
In this work, computational fluid dynamics (CFD)—based simulations and linear diffraction analysis are carried out to investigate the interaction between water waves and metamaterials composed of an array of C-shaped...In this work, computational fluid dynamics (CFD)—based simulations and linear diffraction analysis are carried out to investigate the interaction between water waves and metamaterials composed of an array of C-shaped cylinders. The flow visualization by CFD-based simulations reveals that local resonance is a result of constructive interference between the incident wave and the wave radiated from the cavity of the C-shaped cylinder. The wave-induced water motion inside the cavity acts as a source of generating this radiated wave, which has the same angular wave frequency and wavenumber but opposite propagation direction as the incident wave. In addition, it is found from the CFD-based simulations that the energy dissipation increases as the opening of the C-shaped cylinder becomes shorter and sharper, along with an increase in its outer radius, and the variation trend of energy dissipation is only affected by the outer radius. Meanwhile, except for very small opening lengths, variations in opening length, width, and outer radius do not significantly impact the wave attenuation effect of the C-shaped cylinder array. Moreover, the results obtained by CFD and the linear potential flow model are compared. The linear potential flow theory is proven to be a reliable approach for accurately predicting the local resonant frequency and transmission coefficients within the local resonant band across a range of geometric parameters. However, it is noted that this theory may have limitations when applied to cases with extremely small opening lengths, where it struggles to accurately predict the local resonant frequency and the intensity of local resonance.展开更多
In practical engineering structures,complex low-frequency vibrations are often encountered.However,most reported elastic metamaterials are designed for high-frequency ranges or rely on substantial additional mass to c...In practical engineering structures,complex low-frequency vibrations are often encountered.However,most reported elastic metamaterials are designed for high-frequency ranges or rely on substantial additional mass to control low-frequency vibrations,making them difficult to apply in real-world engineering scenarios.To address this limitation,we propose a homogeneous locally resonance metamaterial with tunable low-frequency bandgaps.This design overcomes the challenges associated with conventional local resonators,which are often large and heavy,making them impractical for engineering applications.By integrating resonator structures composed of elastic chiral spiral beams and mass blocks onto the supporting structure,we achieve lowfrequency vibration control within limited spaces,broadband absorption with gradient parameter units,and vibration control under different curvatures.The effectiveness of the proposed design is validated through comparative computational methods,dispersion curve calculations,frequency response simulations,and experimental tests.This study proposes a novel LRM structure with a full bandgap from 96.9 to 124 Hz.The transmittance is negative in most of the band gap range,which has been verified through numerical and experimental results.This approach effectively meets the complex low-frequency vibration control requirements of various curved structures in engineering applications,providing a viable solution for low-frequency vibration control of structures such as flat and cylindrical shells.展开更多
Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble...Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble metal nanoparticles (Au and Ag) with LSPR feature have found wide applications in solar energy conversion. Numerous metal-based photocatalysts have been proposed including metal/semiconductor heterostructures and plasmonic bimetallic or multimetallic nanostructures. However, high cost and scarce reserve of noble metals largely limit their further practical use, which drives the focus gradually shift to low-cost and abundant nonmetallic nanostructures. Recently, various heavily doped semiconductors (such as WO_(3-x), MoO_(3-x), Cu_(2-x)S, TiN) have emerged as potential alternatives to costly noble metals for efficient photocatalysis due to their strong LSPR property in visible-near infrared region. This review starts with a brief introduction to LSPR property and LSPR-enhanced photocatalysis, the following highlights recent advances of plasmonic photocatalysts from noble metal to semiconductor-based plasmonic nanostructures. Their synthesis methods and promising applicability in plasmon-driven photocatalytic reactions such as water splitting, CO_(2) reduction and pollution decomposition are also summarized in details. This review is expected to give guidelines for exploring more efficient plasmonic systems and provide a perspective on development of plasmonic photocatalysis.展开更多
A locally resonant sonic material （LRSM） is an elastic matrix containing a periodic arrangement of identical local resonators （LRs）, which can reflect strongly near their natural frequencies, where the wavelength ...A locally resonant sonic material （LRSM） is an elastic matrix containing a periodic arrangement of identical local resonators （LRs）, which can reflect strongly near their natural frequencies, where the wavelength in the matrix is still much larger than the structural periodicity. Due to the periodic arrangement, an LRSM can also display a Bragg scattering effect, which is a characteristic of phononic crystals. A specific LRSM which possesses both local resonance and Bragg scattering effects is presented. Via the layered-multiple-scattering theory, the complex band structure and the transmittance of such LRSM are discussed in detail. Through the analysis of the refraction behavior at the boundary of the composite, we find that the transmittance performance of an LRSM for oblique incidence depends on the refraction of its boundary and the transmission behaviors of different wave modes inside the composite. As a result, it is better to use some low-speed materials （compared with the speed of waves in surrounding medium） as the LRSM matrix for designing sound blocking materials in underwater applications, since their acoustic properties are more robust to the incident angle. Finally, a gap-coupled LRSM with a broad sub-wavelength transmission gap is studied, whose acoustic performance is insensitive to the angle of incidence.展开更多
The subwavelength confinement feature of localized surface plasmon resonance（LSPR） allows plasmonic nanostructures to be functionalized as powerful platforms for detecting various molecular analytes as well as weak ...The subwavelength confinement feature of localized surface plasmon resonance（LSPR） allows plasmonic nanostructures to be functionalized as powerful platforms for detecting various molecular analytes as well as weak processes with nanoscale spatial resolution. One of the main goals of this field of research is to lower the absolute limit-of-detection（LOD）of LSPR-based sensors. This involves the improvement of（i） the figure-of-merit associated with structural parameters such as the size, shape and interparticle arrangement and,（ii） the spectral resolution. The latter involves advanced target identification and noise reduction techniques. By highlighting the strategies for improving the LOD, this review introduces the fundamental principles and recent progress of LSPR sensing based on different schemes including 1） refractometric sensing realized by observing target-induced refractive index changes, 2） plasmon rulers based on target-induced relative displacement of coupled plasmonic structures, 3） other relevant LSPR-based sensing schemes including chiral plasmonics,nanoparticle growth, and optomechanics. The ultimate LOD and the future trends of these LSPR-based sensing are also discussed.展开更多
The photocatalytic reduction of CO2 with H2O to fuels and chemicals using solar energy is one of the most attractive but highly difficult routes.Thus far,only a very limited number of photocatalysts has been reported ...The photocatalytic reduction of CO2 with H2O to fuels and chemicals using solar energy is one of the most attractive but highly difficult routes.Thus far,only a very limited number of photocatalysts has been reported to be capable of catalyzing the photocatalytic reduction of CO2 under visible light.The utilization of the localized surface plasmon resonance(LSPR)phenomenon is an attractive strategy for developing visible-light photocatalysts.Herein,we have succeeded in synthesizing plasmonic MoO3?x-TiO2 nanocomposites with tunable LSPR by a simple solvothermal method.The well-structured nanocomposite containing two-dimensional(2D)molybdenum oxide(MoO3?x)nanosheets and one-dimensional(1D)titanium oxide nanotubes(TiO2-NT)showed LSPR absorption band in the visible-light region,and the incorporation of TiO2-NT significantly enhanced the LSPR absorption band.The MoO3?x-TiO2-NT nanocomposite is promising for application in the photocatalytic reduction of CO2 with H2O under visible light irradiation.展开更多
The influences of the anisotropy of the outer spherically anisotropic （SA） layer on the far-field spectra and near- field enhancements of the silver nanoshells are investigated by using a modified Mie scattering the...The influences of the anisotropy of the outer spherically anisotropic （SA） layer on the far-field spectra and near- field enhancements of the silver nanoshells are investigated by using a modified Mie scattering theory. It is found that with the increase of the anisotropic value of the SA layer, the dipole resonance wavelength of the silver nanoshell first increases and then decreases, while the local field factor （LFF） reduces. With the decrease of SA layer thickness, the dipole wavelength of the silver nanoshell shows a distinct blue-shift. When the SA layer becomes very thin, the modulations of the anisotropy of the SA layer on the plasmon resonance energy and the near-field enhancement are weakened. We further find that the smaller anisotropic value of the SA layer is helpful for obtaining the larger near-field enhancement in the Ag nanoshell. The geometric average of the dielectric components of the SA layer has a stronger effect on the plasmon resonance energy of the silver nanoshell than on the near-field enhancement.展开更多
A fast and facile method of fabricating fiber-optic localized surface plasmon resonance sensors baseff on spherical gold nanoparticles was introduced in this study. The gold nanoparticles with an average diameter of 5...A fast and facile method of fabricating fiber-optic localized surface plasmon resonance sensors baseff on spherical gold nanoparticles was introduced in this study. The gold nanoparticles with an average diameter of 55 nm were synthesized via the Turkevich method and were then immobilized onto the surface of an uncladded sensor probe using a polydopamine layer. To obtain a sensor probe with high sensitivity to changes in the refractive index, a set of key optimization parameters, including the sensing length, coating time of the potydopamine layer, and coating time of the gold nanoparticles, were investigated. The sensitivity of the optimized sensor probe was 522.80 nm per refractive index unit, and the probe showed distinctive wavelength shifts when the refractive index was changed from 1.328 6 to 1.398 7. When stored in deionized water at 4 ℃, the sensor probe proved to be stable over a period of two weeks. The sensor also exhibited advantages, such as low cost, fast fabrication, and simple optical setup, which indicated its potential application in remote sensing and real-time detection.展开更多
Lanthanum hexaboride nanopartieles, with high emission electrons in cathode materials and peculiar blocking near infrared wavelengths, were applied for many aspects. Based on the quasi-static approximation of Mie theo...Lanthanum hexaboride nanopartieles, with high emission electrons in cathode materials and peculiar blocking near infrared wavelengths, were applied for many aspects. Based on the quasi-static approximation of Mie theory, the size dependent optical prop- erties of LaB6 nanoparticles were researched, such as refractive index n（ω）, extinction coefficient k（ω）, reflectivity R（ω）, absorption coefficient a（ω）, and electron energy loss L（ω）. Due to the localized surface plasmon resonance （LSPR）, the extinction coefficient k（ω） and absorption coefficient a（ω） depended on the size, and the LSPR peaks red-shifted with sizes increased, which was different from that of bulk materials. In addition, electron energy-loss spectrum L（co） showed electrons oscillation reinforced, since electrons absorbed the photon energy and generated resonance. Further, reftectivity R（ω） and refractive index n（ω） indicated that the light in near infrared region could not be propagated on the surface of LaB6 materials, which exhibited metallic behaviors. So the resonance peak of LaB6 nanoparticle was located in near-infrared region, making use of this property for solar control glazing and heat-shielding application.展开更多
An optical biosensor is a specialized analytical device that utilizes the principles of optics and light in bimolecular processes.Localized surface plasmon resonance(LSPR)is a phenomenon in the realm of nanophotonics ...An optical biosensor is a specialized analytical device that utilizes the principles of optics and light in bimolecular processes.Localized surface plasmon resonance(LSPR)is a phenomenon in the realm of nanophotonics that occurs when metallic nanoparticles(NPs)or nanostructures interact with incident light.Conversely,surface-enhanced Raman spectroscopy(SERS)is an influential analytical technique based on Raman scattering,wherein it amplifies the Raman signals of molecules when they are situated near specific and specially designed nanostructures.A detailed exploration of the recent groundbreaking developments in optical biosensors employing LSPR and SERS technologies has been thoroughly discussed along with their underlying principles and the working mechanisms.A biosensor chip has been created,featuring a high-density deposition of gold nanoparticles(AuNPs)under varying ligand concentration and reaction duration on the substrate.An ordinary description,along with a visual illustration,has been thoroughly provided for concepts such as a sensogram,refractive index shift,surface plasmon resonance(SPR),and the evanescent field,Rayleigh scattering,Raman scattering,as well as the electromagnetic enhancement and chemical enhancement.LSPR and SERS both have advantages and disadvantages,but widely used SERS has some advantages over LSPR,like chemical specificity,high sensitivity,multiplexing,and versatility in different fields.This review confirms and elucidates the significance of different disease biomarker identification.LSPR and SERS both play a vital role in the detection of various types of cancer,such as cervical cancer,ovarian cancer,endometrial cancer,prostate cancer,colorectal cancer,and brain tumors.This proposed optical biosensor offers potential applications for early diagnosis and monitoring of viral disease,bacterial infectious diseases,fungal diseases,diabetes,and cardiac disease biosensing.LSPR and SERS provide a new direction for environmental monitoring,food safety,refining impurities from water samples,and lead detection.The understanding of these biosensors is still limited and challenging.展开更多
Detection of local strain at the nanometer scale with high sensitivity remains challenging.Here we report near-field infrared nano-imaging of local strains in bilayer graphene by probing strain-induced shifts of phono...Detection of local strain at the nanometer scale with high sensitivity remains challenging.Here we report near-field infrared nano-imaging of local strains in bilayer graphene by probing strain-induced shifts of phonon frequency.As a non-polar crystal,intrinsic bilayer graphene possesses little infrared response at its transverse optical phonon frequency.The reported optical detection of local strain is enabled by applying a vertical electrical field that breaks the symmetry of the two graphene layers and introduces finite electrical dipole moment to graphene phonon.The activated phonon further interacts with continuum electronic transitions,and generates a strong Fano resonance.The resulted Fano resonance features a very sharp near-field infrared scattering peak,which leads to an extraordinary sensitivity of-0.002%for the strain detection.Our results demonstrate the first nano-scale near-field Fano resonance,provide a new way to probe local strains with high sensitivity in non-polar crystals,and open exciting possibilities for studying strain-induced rich phenomena.展开更多
Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through va...Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through varying the difference admittance ratio η[= （ε2 - ε0）/（ε1 - ε0）], we find that their optical responses are determined by the local resonance. There is a blueshift of absorption peaks with the increase of η- Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances, we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-component composites εe=ε0 （1＋∑^n n=1[（γn1＋ηγn2）/（ε0（s-sn））]） and the sum rule of cross sections：∑^n n=1（γn1＋ηγn2）=Nh1＋Nh2,, where Nh1and Nh2 are the numbers of εl and ε2 bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.展开更多
According to the plasmon hybridization theory, the plasmon resonance characteristics of the gold nanocrescent/nanoring(NCNR) structure are systematically investigated by the finite element method. It is found that the...According to the plasmon hybridization theory, the plasmon resonance characteristics of the gold nanocrescent/nanoring(NCNR) structure are systematically investigated by the finite element method. It is found that the extinction spectra of NCNR structure exhibit multiple plasmon resonance peaks, which could be attributed to the result of the plasmon couplings between the multipolar plasmon modes of nanocrescent and the dipolar, quadrupolar, hexapolar, octupolar,decapolar plasmon modes of nanoring. By changing the geometric parameters, the intense and separate multiple plasmon resonance peaks are obtained and can be tuned in a wide wavelength range. It is further found that the plasmon coupling induces giant multipole electric field enhancements around the tips of the nanocrescent. The tunable and intense multiple plasmon resonances of NCNR structure may provide effective applications in multiplex biological sensing.展开更多
Localized surface plasmon （LSPR） resonance and sensing properties of a novel nanostructure （sexfoil nanoparticle） are studied using the finite-difference time-domain method. For the sandwich sexfoil nanoparticle, ...Localized surface plasmon （LSPR） resonance and sensing properties of a novel nanostructure （sexfoil nanoparticle） are studied using the finite-difference time-domain method. For the sandwich sexfoil nanoparticle, the calculated extinction spectrum shows that with the thickness of the dielectric layer increasing, long-wavelength peaks blueshift, while short- wavelength peaks redshift. Strong near-field coupling of the upper and lower metal layers leads to electric and magnetic field resonances; as the thickness increases, the electric field resonance gradually increases, while the magnetic field resonance decreases. The obtained refractive index sensitivity and figure of merit are 332 nm/RIU and 3.91 RIU^-1, respectively. In order to obtain better sensing ability, we further research the LSPR character of monolayer Ag sexfoil nanoparticle. After a series of trials to optimize the thickness and shape, the refractive index sensitivity approximates 668 nm/RIU, and the greatest figure of merit value comes to 14.8 RIU^-1.展开更多
基金Natural Science Foundation of China under Grant No.42277130Natural Science Foundation of Shandong Province under Grant No.ZR2021ME144。
文摘With the acceleration of urbanization,environmental vibration and noise pollution have become increasingly severe,and traditional vibration and noise reduction technologies are insufficient to meet current vibration control requirements.This study,based on locally resonant theory,designed a novel local resonance periodic block(LRPB).Using the plane wave expansion method(PWEM)and the finite element method(FEM),this study investigated the bandgap characteristics,formation mechanisms,and vibration and acoustic performance of an LRPB under different periodic structures and material selection.The vibration reduction and noise reduction performance of LRPB has been validated through the Qingdao metro project.The research results show that the LRPB is superior to other periodic structures in terms of wide bandgap.Furthermore,configuring soft scatterer material,increasing the unit size,enhancing the material filling rate,and adopting a honeycomb arrangement can effectively reduce bandgap frequency.In structural design,non-high symmetry demonstrates greater advantages.In a study of a subway tunnel,the LRPB demonstrated superior vibration and noise mitigation performance compared to wave impeding block(WIB),thereby demonstrating potential for use in the field of vibration and noise reduction with regard to structures.
基金Project(2016YFE0205200)supported by the National Key Research and Development Program of ChinaProjects(51425804,51508479)supported by the National Natural Science Foundation of China+1 种基金Project(2016310019)supported by the Doctorial Innovation Fund of Southwest Jiaotong University,ChinaProject(2017GZ0373)supported by the Research Fund for Key Research and Development Projects in Sichuan Province,China
文摘Excessive vibration and noise radiation of the track structure can be caused by the operation of high speed trains.Though the track structure is characterized by obvious periodic properties and band gaps,the bandwidth is narrow and the elastic wave attenuation capability within the band gap is weak.In order to effectively control the vibration and noise of track structure,the local resonance mechanism is introduced to broaden the band gap and realize wave propagation control.The locally resonant units are attached periodically on the rail,forming a new locally resonant phononic crystal structure.Then the tuning of the elastic wave band gaps of track structure is discussed,and the formation mechanism of the band gap is explicated.The research results show that a new wide and adjustable locally resonant band gap is formed after the resonant units are introduced.The phenomenon of coupling and transition can be observed between the new locally resonant band gap and the original band gap of the periodic track structure with the band gap width reaching the maximum at the coupling position.The broader band gap can be applied for vibration and noise reduction in high speed railway track structure.
基金the National Natural Science Foundation of China(Nos.11872127,11832002,11732005)Qin Xin Talents Cultivation Program of Beijing Information Science and Technology University(No.QXTCP A201901)the Project High-Level Innovative Team Building Plan for Beijing Municipal Colleges and Universities(No.IDHT20180513)。
文摘The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural vibration reduction.In this paper,a novel sandwich-like plate model with local resonator to acquire specific low-frequency bandgaps is proposed.The core layer of the present local resonator is composed by the simply supported overhanging beam,linear spring and mass block,and well connected with the upper and lower surface panels.The simply supported overhanging beam is free at right end,and an additional linear spring is added at the left end.The wave equation is established based on the Hamilton principle,and the bending wave bandgap is further obtained.The theoretical results are verified by the COMSOL finite element software.The bandgaps and vibration characteristics of the local resonance sandwich-like plate are studied in detail.The factors which could have effects on the bandgap characteristics,such as the structural damping,mass of vibrator,position of vibrator,bending stiffness of the beam,and the boundary conditions of the sandwich-like plates,are analyzed.The result shows that the stopband is determined by the natural frequency of the resonator,the mass ratio of the resonator,and the surface panel.It shows that the width of bandgap is greatly affected by the damping ratio of the resonator.Finally,it can also be found that the boundary conditions can affect the isolation efficiency.
文摘In 1982, Professor Fang Guoliang found the "Non full resonance" phenomenon in a tool system while he use the thin-long tool ultrasonically machining deep-small hole. He called it as "local resonance". Also this "Non full resonance" phenomenon was discovered in the ultrasonic drilling and the ultrasonic honing system later. To its mechanism, professor Fang thought that the coupling of long-thin tool bar and driving system is weak, so the tool bar can vibrate independently, but the quantitative relation between the coupling factor and diameter ratio is not made certain. Then several theories come forth to interpret it but still haven’t a common conclusion. Through the systematic experimental and theoretical research, this paper reveals that the "local resonance" phenomenon of ultrasonic honing system has the same essence with the "local resonance" phenomenon in deep hole machining system: when the section area ratio of tool bar and driving system is small enough, some resonance frequencies of combined system are close to the resonance frequencies of "fixed-free" state tool bar, the combined system is still resonant. According to the given depth of hole and structure size, we can use the transfer matrix deduced in this paper to design flexible bar and oilstone seat not only satisfying mechanical structure size but also achieving enough magnitude. It greatly simplified the design. This new method can be named as "local resonance" design method for ultrasonic honing system. The experiment, deduction and design method have a certain common meaning to the study and design of other ultrasonic system.
基金supported by the National Natural Science Foundation of China(Nos.11991032 and 52241103)。
文摘To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes,a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed.First,an integrated design method is proposed for the longitudinal and transverse wave control of fluid-conveying pipes,and a novel periodic structure unit model is constructed for vibration reduction.Based on the bandgap vibration reduction mechanism of the acoustic metamaterial periodic structure,the material parameters,structural parameters,and the arrangement interval of the periodic structure unit are optimized.The finite element method(FEM)is used to predict the vibration transmission characteristics of the fluid-conveying pipe installed with the vibration reduction periodic structure.Then,the wave/spectrum element method(WSEM)and experimental test are used to verify the calculated results above.Lastly,the vibration attenuation characteristics of the structure under different conditions,such as rubber material parameters,mass ring material,and fluid-structure coupling effect,are analyzed.The results show that the structure can produce a complete bandgap of 46 Hz-75 Hz in the low-frequency band below 100 Hz,which can effectively suppress the low broadband vibration of the fluidconveying pipe.In addition,a high damping rubber material is used in the design of the periodic structure unit,which realizes the effective suppression of each formant peak of the pipe,and improves the vibration reduction effect of the fluid-conveying pipe.Meanwhile,the structure has the effect of suppressing both bending vibration and longitudinal vibration,and effectively inhibits the transmission of transverse waves and longitudinal waves in the pipe.The research results provide a reference for the application of acoustic metamaterials in the multi-directional vibration control of fluid-conveying pipes.
基金financially supported by the National Natural Science Foundation of China(No.22268003)the projects from Yunnan Province(No.202305AF150116).
文摘An emerging ZnO/CuInS_(2) S-scheme heterojunction enables the transformation of ZnO,originally limited to ultraviolet light absorption,into a composite with a strong near-infrared response.The charge transfer from the p-type semiconductor CuInS_(2) to the n-type semiconductor ZnO leads to an increased hole concentration in the CuInS_(2) quantum dots at the heterojunction interface.Consequently,this enhancement not only amplifies the localized surface plasmon resonance effect but also enhances the near-infrared light absorption of CuInS_(2) quantum dots.This strategy effectively addresses common light response challenges,advancing the overarching objective of utilizing the full solar spectrum.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U22A20242,52271260 and 52371263).
文摘In this work, computational fluid dynamics (CFD)—based simulations and linear diffraction analysis are carried out to investigate the interaction between water waves and metamaterials composed of an array of C-shaped cylinders. The flow visualization by CFD-based simulations reveals that local resonance is a result of constructive interference between the incident wave and the wave radiated from the cavity of the C-shaped cylinder. The wave-induced water motion inside the cavity acts as a source of generating this radiated wave, which has the same angular wave frequency and wavenumber but opposite propagation direction as the incident wave. In addition, it is found from the CFD-based simulations that the energy dissipation increases as the opening of the C-shaped cylinder becomes shorter and sharper, along with an increase in its outer radius, and the variation trend of energy dissipation is only affected by the outer radius. Meanwhile, except for very small opening lengths, variations in opening length, width, and outer radius do not significantly impact the wave attenuation effect of the C-shaped cylinder array. Moreover, the results obtained by CFD and the linear potential flow model are compared. The linear potential flow theory is proven to be a reliable approach for accurately predicting the local resonant frequency and transmission coefficients within the local resonant band across a range of geometric parameters. However, it is noted that this theory may have limitations when applied to cases with extremely small opening lengths, where it struggles to accurately predict the local resonant frequency and the intensity of local resonance.
基金supported by the National Key Research and Development Plan of China(Grant No.2023YFB3406302)the National Natural Science Foundation of China(Grant No.52175120)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515011126)。
文摘In practical engineering structures,complex low-frequency vibrations are often encountered.However,most reported elastic metamaterials are designed for high-frequency ranges or rely on substantial additional mass to control low-frequency vibrations,making them difficult to apply in real-world engineering scenarios.To address this limitation,we propose a homogeneous locally resonance metamaterial with tunable low-frequency bandgaps.This design overcomes the challenges associated with conventional local resonators,which are often large and heavy,making them impractical for engineering applications.By integrating resonator structures composed of elastic chiral spiral beams and mass blocks onto the supporting structure,we achieve lowfrequency vibration control within limited spaces,broadband absorption with gradient parameter units,and vibration control under different curvatures.The effectiveness of the proposed design is validated through comparative computational methods,dispersion curve calculations,frequency response simulations,and experimental tests.This study proposes a novel LRM structure with a full bandgap from 96.9 to 124 Hz.The transmittance is negative in most of the band gap range,which has been verified through numerical and experimental results.This approach effectively meets the complex low-frequency vibration control requirements of various curved structures in engineering applications,providing a viable solution for low-frequency vibration control of structures such as flat and cylindrical shells.
基金supported by the National Natural Science Foundation of China (Nos. 11904133, 51872125)Guangdong Natural Science Funds for Distinguished Young Scholar (No. 2018B030306004) and GDUPS (2018)+1 种基金the Fundamental Research Funds for the Central Universities (No. 21619322)Regional Joint Foundation in Guangdong Province (No. 2019A1515110210)。
文摘Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble metal nanoparticles (Au and Ag) with LSPR feature have found wide applications in solar energy conversion. Numerous metal-based photocatalysts have been proposed including metal/semiconductor heterostructures and plasmonic bimetallic or multimetallic nanostructures. However, high cost and scarce reserve of noble metals largely limit their further practical use, which drives the focus gradually shift to low-cost and abundant nonmetallic nanostructures. Recently, various heavily doped semiconductors (such as WO_(3-x), MoO_(3-x), Cu_(2-x)S, TiN) have emerged as potential alternatives to costly noble metals for efficient photocatalysis due to their strong LSPR property in visible-near infrared region. This review starts with a brief introduction to LSPR property and LSPR-enhanced photocatalysis, the following highlights recent advances of plasmonic photocatalysts from noble metal to semiconductor-based plasmonic nanostructures. Their synthesis methods and promising applicability in plasmon-driven photocatalytic reactions such as water splitting, CO_(2) reduction and pollution decomposition are also summarized in details. This review is expected to give guidelines for exploring more efficient plasmonic systems and provide a perspective on development of plasmonic photocatalysis.
基金the China Scholarship Council for funding him to study at the University of Southampton in the UK
文摘A locally resonant sonic material （LRSM） is an elastic matrix containing a periodic arrangement of identical local resonators （LRs）, which can reflect strongly near their natural frequencies, where the wavelength in the matrix is still much larger than the structural periodicity. Due to the periodic arrangement, an LRSM can also display a Bragg scattering effect, which is a characteristic of phononic crystals. A specific LRSM which possesses both local resonance and Bragg scattering effects is presented. Via the layered-multiple-scattering theory, the complex band structure and the transmittance of such LRSM are discussed in detail. Through the analysis of the refraction behavior at the boundary of the composite, we find that the transmittance performance of an LRSM for oblique incidence depends on the refraction of its boundary and the transmission behaviors of different wave modes inside the composite. As a result, it is better to use some low-speed materials （compared with the speed of waves in surrounding medium） as the LRSM matrix for designing sound blocking materials in underwater applications, since their acoustic properties are more robust to the incident angle. Finally, a gap-coupled LRSM with a broad sub-wavelength transmission gap is studied, whose acoustic performance is insensitive to the angle of incidence.
基金Project supported by the National Key Basic Research Program(Grant No.2015CB932400)the National Key Research and Development Program of China(Grant Nos.2017YFA0205800 and 2017YFA0303504)the National Natural Science Foundation of China(Grant Nos.11674255 and 11674256)
文摘The subwavelength confinement feature of localized surface plasmon resonance（LSPR） allows plasmonic nanostructures to be functionalized as powerful platforms for detecting various molecular analytes as well as weak processes with nanoscale spatial resolution. One of the main goals of this field of research is to lower the absolute limit-of-detection（LOD）of LSPR-based sensors. This involves the improvement of（i） the figure-of-merit associated with structural parameters such as the size, shape and interparticle arrangement and,（ii） the spectral resolution. The latter involves advanced target identification and noise reduction techniques. By highlighting the strategies for improving the LOD, this review introduces the fundamental principles and recent progress of LSPR sensing based on different schemes including 1） refractometric sensing realized by observing target-induced refractive index changes, 2） plasmon rulers based on target-induced relative displacement of coupled plasmonic structures, 3） other relevant LSPR-based sensing schemes including chiral plasmonics,nanoparticle growth, and optomechanics. The ultimate LOD and the future trends of these LSPR-based sensing are also discussed.
文摘The photocatalytic reduction of CO2 with H2O to fuels and chemicals using solar energy is one of the most attractive but highly difficult routes.Thus far,only a very limited number of photocatalysts has been reported to be capable of catalyzing the photocatalytic reduction of CO2 under visible light.The utilization of the localized surface plasmon resonance(LSPR)phenomenon is an attractive strategy for developing visible-light photocatalysts.Herein,we have succeeded in synthesizing plasmonic MoO3?x-TiO2 nanocomposites with tunable LSPR by a simple solvothermal method.The well-structured nanocomposite containing two-dimensional(2D)molybdenum oxide(MoO3?x)nanosheets and one-dimensional(1D)titanium oxide nanotubes(TiO2-NT)showed LSPR absorption band in the visible-light region,and the incorporation of TiO2-NT significantly enhanced the LSPR absorption band.The MoO3?x-TiO2-NT nanocomposite is promising for application in the photocatalytic reduction of CO2 with H2O under visible light irradiation.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB921504)the National Natural Science Foundation of China(Grant Nos.10904052,11174113,and 11104319)+1 种基金the Jiangsu Planned Projects for Postdoctoral Research Funds,China(Grant No.1002075C)the Senior Talent Foundation of Jiangsu University,China(Grant No.09JDG073)
文摘The influences of the anisotropy of the outer spherically anisotropic （SA） layer on the far-field spectra and near- field enhancements of the silver nanoshells are investigated by using a modified Mie scattering theory. It is found that with the increase of the anisotropic value of the SA layer, the dipole resonance wavelength of the silver nanoshell first increases and then decreases, while the local field factor （LFF） reduces. With the decrease of SA layer thickness, the dipole wavelength of the silver nanoshell shows a distinct blue-shift. When the SA layer becomes very thin, the modulations of the anisotropy of the SA layer on the plasmon resonance energy and the near-field enhancement are weakened. We further find that the smaller anisotropic value of the SA layer is helpful for obtaining the larger near-field enhancement in the Ag nanoshell. The geometric average of the dielectric components of the SA layer has a stronger effect on the plasmon resonance energy of the silver nanoshell than on the near-field enhancement.
基金Supported by the Ministry of Science and Technology of China(No.2012YQ090194)the National Natural Science Foundation of China(No.51473115)
文摘A fast and facile method of fabricating fiber-optic localized surface plasmon resonance sensors baseff on spherical gold nanoparticles was introduced in this study. The gold nanoparticles with an average diameter of 55 nm were synthesized via the Turkevich method and were then immobilized onto the surface of an uncladded sensor probe using a polydopamine layer. To obtain a sensor probe with high sensitivity to changes in the refractive index, a set of key optimization parameters, including the sensing length, coating time of the potydopamine layer, and coating time of the gold nanoparticles, were investigated. The sensitivity of the optimized sensor probe was 522.80 nm per refractive index unit, and the probe showed distinctive wavelength shifts when the refractive index was changed from 1.328 6 to 1.398 7. When stored in deionized water at 4 ℃, the sensor probe proved to be stable over a period of two weeks. The sensor also exhibited advantages, such as low cost, fast fabrication, and simple optical setup, which indicated its potential application in remote sensing and real-time detection.
基金supported by National Natural Science Foundation of China(60907021,60977035,60877029)Tianjin Natural Science Foundation(11JCYBJC00300)
文摘Lanthanum hexaboride nanopartieles, with high emission electrons in cathode materials and peculiar blocking near infrared wavelengths, were applied for many aspects. Based on the quasi-static approximation of Mie theory, the size dependent optical prop- erties of LaB6 nanoparticles were researched, such as refractive index n（ω）, extinction coefficient k（ω）, reflectivity R（ω）, absorption coefficient a（ω）, and electron energy loss L（ω）. Due to the localized surface plasmon resonance （LSPR）, the extinction coefficient k（ω） and absorption coefficient a（ω） depended on the size, and the LSPR peaks red-shifted with sizes increased, which was different from that of bulk materials. In addition, electron energy-loss spectrum L（co） showed electrons oscillation reinforced, since electrons absorbed the photon energy and generated resonance. Further, reftectivity R（ω） and refractive index n（ω） indicated that the light in near infrared region could not be propagated on the surface of LaB6 materials, which exhibited metallic behaviors. So the resonance peak of LaB6 nanoparticle was located in near-infrared region, making use of this property for solar control glazing and heat-shielding application.
文摘An optical biosensor is a specialized analytical device that utilizes the principles of optics and light in bimolecular processes.Localized surface plasmon resonance(LSPR)is a phenomenon in the realm of nanophotonics that occurs when metallic nanoparticles(NPs)or nanostructures interact with incident light.Conversely,surface-enhanced Raman spectroscopy(SERS)is an influential analytical technique based on Raman scattering,wherein it amplifies the Raman signals of molecules when they are situated near specific and specially designed nanostructures.A detailed exploration of the recent groundbreaking developments in optical biosensors employing LSPR and SERS technologies has been thoroughly discussed along with their underlying principles and the working mechanisms.A biosensor chip has been created,featuring a high-density deposition of gold nanoparticles(AuNPs)under varying ligand concentration and reaction duration on the substrate.An ordinary description,along with a visual illustration,has been thoroughly provided for concepts such as a sensogram,refractive index shift,surface plasmon resonance(SPR),and the evanescent field,Rayleigh scattering,Raman scattering,as well as the electromagnetic enhancement and chemical enhancement.LSPR and SERS both have advantages and disadvantages,but widely used SERS has some advantages over LSPR,like chemical specificity,high sensitivity,multiplexing,and versatility in different fields.This review confirms and elucidates the significance of different disease biomarker identification.LSPR and SERS both play a vital role in the detection of various types of cancer,such as cervical cancer,ovarian cancer,endometrial cancer,prostate cancer,colorectal cancer,and brain tumors.This proposed optical biosensor offers potential applications for early diagnosis and monitoring of viral disease,bacterial infectious diseases,fungal diseases,diabetes,and cardiac disease biosensing.LSPR and SERS provide a new direction for environmental monitoring,food safety,refining impurities from water samples,and lead detection.The understanding of these biosensors is still limited and challenging.
基金Supported by the National Key Research and Development Program of China (Grant No.2016YFA0302001)the National Natural Science Foundation of China (Grant Nos.11774224,12074244,11521404,and 61701394)+1 种基金support from the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learningadditional support from a Shanghai talent program。
文摘Detection of local strain at the nanometer scale with high sensitivity remains challenging.Here we report near-field infrared nano-imaging of local strains in bilayer graphene by probing strain-induced shifts of phonon frequency.As a non-polar crystal,intrinsic bilayer graphene possesses little infrared response at its transverse optical phonon frequency.The reported optical detection of local strain is enabled by applying a vertical electrical field that breaks the symmetry of the two graphene layers and introduces finite electrical dipole moment to graphene phonon.The activated phonon further interacts with continuum electronic transitions,and generates a strong Fano resonance.The resulted Fano resonance features a very sharp near-field infrared scattering peak,which leads to an extraordinary sensitivity of-0.002%for the strain detection.Our results demonstrate the first nano-scale near-field Fano resonance,provide a new way to probe local strains with high sensitivity in non-polar crystals,and open exciting possibilities for studying strain-induced rich phenomena.
基金Project supported by the National Natural Science Foundation of China（Grant Nos 10304001, 10334010, 10521002, 10434020, 10328407 and 90501007）.
文摘Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through varying the difference admittance ratio η[= （ε2 - ε0）/（ε1 - ε0）], we find that their optical responses are determined by the local resonance. There is a blueshift of absorption peaks with the increase of η- Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances, we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-component composites εe=ε0 （1＋∑^n n=1[（γn1＋ηγn2）/（ε0（s-sn））]） and the sum rule of cross sections：∑^n n=1（γn1＋ηγn2）=Nh1＋Nh2,, where Nh1and Nh2 are the numbers of εl and ε2 bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.
基金supported by the National Natural Science Foundation of China(Grant Nos.61275153 and 61320106014)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY12A04002)+1 种基金the Natural Science Foundation of Ningbo City,China(Grant Nos.2010D10018 and 2012A610107)the K.C.Wong Magna Foundation of Ningbo University,China
文摘According to the plasmon hybridization theory, the plasmon resonance characteristics of the gold nanocrescent/nanoring(NCNR) structure are systematically investigated by the finite element method. It is found that the extinction spectra of NCNR structure exhibit multiple plasmon resonance peaks, which could be attributed to the result of the plasmon couplings between the multipolar plasmon modes of nanocrescent and the dipolar, quadrupolar, hexapolar, octupolar,decapolar plasmon modes of nanoring. By changing the geometric parameters, the intense and separate multiple plasmon resonance peaks are obtained and can be tuned in a wide wavelength range. It is further found that the plasmon coupling induces giant multipole electric field enhancements around the tips of the nanocrescent. The tunable and intense multiple plasmon resonances of NCNR structure may provide effective applications in multiplex biological sensing.
基金supported by the Sichuan Provincial Department of Education,China(Grant No.16ZA0047)the State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,China(Grant No.201509)+1 种基金the Large Precision Instruments Open Project Foundation of Sichuan Normal University,China(Grant Nos.DJ201557,DJ201558 and DJ201560)the State Key Laboratory of Optical Technologies on Nano Fabrication and Micro Engineering,Institute of Optics and Electronics,Chinese Academy of Sciences
文摘Localized surface plasmon （LSPR） resonance and sensing properties of a novel nanostructure （sexfoil nanoparticle） are studied using the finite-difference time-domain method. For the sandwich sexfoil nanoparticle, the calculated extinction spectrum shows that with the thickness of the dielectric layer increasing, long-wavelength peaks blueshift, while short- wavelength peaks redshift. Strong near-field coupling of the upper and lower metal layers leads to electric and magnetic field resonances; as the thickness increases, the electric field resonance gradually increases, while the magnetic field resonance decreases. The obtained refractive index sensitivity and figure of merit are 332 nm/RIU and 3.91 RIU^-1, respectively. In order to obtain better sensing ability, we further research the LSPR character of monolayer Ag sexfoil nanoparticle. After a series of trials to optimize the thickness and shape, the refractive index sensitivity approximates 668 nm/RIU, and the greatest figure of merit value comes to 14.8 RIU^-1.
