Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure throug...Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.展开更多
To analyze the band gap characteristics of phononic crystals,a two-dimensional phononic crystal plate model with an elastic foundation was first established.The plane wave expansion method was used to compute the disp...To analyze the band gap characteristics of phononic crystals,a two-dimensional phononic crystal plate model with an elastic foundation was first established.The plane wave expansion method was used to compute the dispersion curves of this phononic crystal model,and the results were compared with those from the finite element method to verify their accuracy.Subsequently,a parameter study explored the effects of the elastic foundation coeffi-cient and coverage ratio on the band gap.The results indicate that as the coverage ratio of the elastic foundation increases,the band gap significantly expands,reaching its maximum value at 100%coverage.Additionally,as the elastic foundation stiffness increases,the band gap gradually widens and converges toward fixed boundary conditions.The study also investigated the band gap of phononic crystal plates with defects,finding that the vibrational energy concentrates at the defect unit cell.Furthermore,the defect band frequency can be effectively modulated by adjusting the coefficient of the elastic foundation,providing a theoretical basis for achieving efficient energy conversion.展开更多
This study investigates the nonlinear resonance responses of suspended cables subjected to multi-frequency excitations and time-delayed feedback.Two specific combinations and simultaneous resonances are selected for d...This study investigates the nonlinear resonance responses of suspended cables subjected to multi-frequency excitations and time-delayed feedback.Two specific combinations and simultaneous resonances are selected for detailed examination.Initially,utilizing Hamilton’s variational principle,a nonlinear vibration control model of suspended cables under multi-frequency excitations and longitudinal time-delayed velocity feedback is developed,and the Galerkin method is employed to obtain the discrete model.Subsequently,focusing solely on single-mode discretization,analytical solutions for the two simultaneous resonances are derived using the method of multiple scales.The frequency response equations are derived,and the stability analysis is presented for two simultaneous resonance cases.The results demonstrate that suspended cables exhibit complex nonlinearity under multi-frequency excitations.Multiple solutions under multi-frequency excitation can be distinguished through the frequency–response and the detuning-phase curves.By adjusting the control gain and time delay,the resonance range,response amplitude,and phase of suspended cables can be modified.展开更多
The advancement of imaging resolution has made the impact of multi-frequency composite jitter in satellite platforms on non-collinear time delay and integration(TDI)charge-coupled device(CCD)imaging systems increasing...The advancement of imaging resolution has made the impact of multi-frequency composite jitter in satellite platforms on non-collinear time delay and integration(TDI)charge-coupled device(CCD)imaging systems increasingly critical.Moreover,the accuracy of jitter detection is constrained by the limited inter-chip overlap region inherent to non-collinear TDI CCDs.To address these challenges,a multi-frequency jitter detection method is proposed,achieving sub-pixel level error extraction.Furthermore,a multi-frequency jitter fitting approach utilizing a scale-adjustable sliding window is introduced.For composite multi-frequency jitter,spectral analysis decomposes the relative jitter error curve,while the scale-adjustable sliding window enables frequency-division fitting and modeling.Validation experiments using Gaofen-8(GF-8)remote sensing satellite imagery detected jitter at 0.65,20,and 100 Hz in the cross-track direction and at 0.5,100,and 120 Hz in the along-track direction,demonstrating the method’s precision in detecting platform jitter at sub-pixel accuracy(<0.2 pixels)and its efficacy in fitting and modeling for non-collinear TDI CCD imaging systems subject to multi-frequency jitter.展开更多
Flat electronic bands in condensed matter provide a rich avenue for exploring novel quantum phenomena. Here, we report an optical spectroscopy study of a topological hourglass semimetal Nb_(3)SiTe_(6) with the electri...Flat electronic bands in condensed matter provide a rich avenue for exploring novel quantum phenomena. Here, we report an optical spectroscopy study of a topological hourglass semimetal Nb_(3)SiTe_(6) with the electric field of the incident light parallel to its crystalline ab-plane. The ab-plane optical conductivity spectra of Nb_(3)SiTe_(6) single crystals exhibit a remarkable peak-like feature around 1.20 eV, which is mainly contributed by the direct optical transitions between the two ab-initio-calculation-derived flat bands along the momentum direction Z–U. Our results pave the way for investigating exotic quantum phenomena based on the flat bands in topological hourglass semimetals.展开更多
BACKGROUND The generation of intrabony defects due to the iatrogenic use of elastic bands is an undesirable situation that can result in persistent gingival inflammation with subsequent bone degradation,thus ultimatel...BACKGROUND The generation of intrabony defects due to the iatrogenic use of elastic bands is an undesirable situation that can result in persistent gingival inflammation with subsequent bone degradation,thus ultimately leading to tooth loss.CASE SUMMARY This clinical case involved a 27-year-old male patient who complained of persistent inflammation and bleeding in the upper anterior region of the gums,despite having undergone dental cleaning for at least 4 years.The dental and medical history indicated the use of removable orthodontic appliances for 8 years,after which braces were placed for 2 years.The intraoral evaluation revealed inflammation and localized suppuration in teeth 11 and 12.Measurements of 2-7 mm for probing depth and 1-5 mm for clinical attachment loss were detected,and combined bone loss was observed via radiographs.Based on the clinical and radiographic findings,localized stage III,grade C periodontitis was diagnosed.During subgingival debridement,two elastic bands emerged around the involved teeth.The bone defects persisted;therefore,they were surgically addressed using a papilla preservation flap and guided tissue regeneration(GTR).CONCLUSION The use of elastic bands of various sizes and elasticities is often essential in multiple orthodontic treatments.However,it is crucial to perform a thorough check-up for each patient during treatment and at the end of treatment to remove any remaining residue of resin,metal bands,or orthodontic bands.Additionally,it is imperative to inform the patients of the importance of attending their follow-up appointments.The use of elastic bands in orthodontics requires special care;moreover,GTR is a management option for intrabony defects associated with the iatrogenic use of bands.展开更多
Fe-based superconductors represent a fascinating class of materials,extensively studied for their complex interplay of superconductivity,magnetism,spin density waves,and nematicity,along with the interactions among th...Fe-based superconductors represent a fascinating class of materials,extensively studied for their complex interplay of superconductivity,magnetism,spin density waves,and nematicity,along with the interactions among these orders.An intriguing yet unexplained phenomenon observed in Fe-based superconductors is the emergence of superconductivity below 25K in the non-superconducting parent compound SrFe_(2)As_(2)following exposure to water at its surface.In this study,we employed in situ angle-resolved photoemission spectroscopy and low-energy electron diffraction to meticulously examine the electronic structure evolution of SrFe_(2)As_(2)upon in situ water dosing.Our findings indicate that water dosing markedly attenuates the spin density wave phase and surface Sr reconstruction while preserving the nematic order in SrFe_(2)As_(2).Furthermore,we detected an enhancement in the spectral weight of bands near the Fermi level.Our observations highlight the critical role of the intricate interplay among various orders induced by water dosing,which effectively modifies the band structure and favors the emergence of superconductivity in SrFe_(2)As_(2).展开更多
Systems hosting flat bands offer a powerful platform for exploring strong correlation physics.Theoretically,topological degeneracy arising in systems with non-trivial topological orders on periodic manifolds of non-ze...Systems hosting flat bands offer a powerful platform for exploring strong correlation physics.Theoretically,topological degeneracy arising in systems with non-trivial topological orders on periodic manifolds of non-zero genus can generate ideal flat bands.However,experimental realization of such geometrically engineered systems is very difficult.In this work,we demonstrate that flat planes with strategically patterned hole defects can engineer ideal flat bands.We construct two families of models:singular flat band systems where degeneracy is stabilized by non-contractible loop excitations tied to hole defects and perfectly nested van Hove systems where degeneracy arises from line excitations in momentum space.These models circumvent the need for exotic manifolds while retaining the essential features of topological flat bands.By directly linking defect engineering to degeneracy mechanisms,our results establish a scalable framework for experimentally accessible flat band design.展开更多
The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics simulation.Remarkably,non-uniform plastic deformation was observed in the sample.At ...The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics simulation.Remarkably,non-uniform plastic deformation was observed in the sample.At high strain rates,amorphization occurred near the edge of the contact region where severe shear strain induced a large number of stacking faults(SFs)and dislocations.In contrast,the central part of the contact region underwent less deformation with significantly fewer dislocations.Moreover,instead of amorphization by consuming SFs and dislocations,there was a gradual increase in the density of dislocations and SFs during the process of amorphization.These local amorphous regions eventually grew into shear bands.展开更多
Extending the ionic conductivity is the pre-requisite of electrolytes in fuel cell technology for high-electrochemical performance.In this regard,the introduction of semiconductor-oxide materials and the approach of h...Extending the ionic conductivity is the pre-requisite of electrolytes in fuel cell technology for high-electrochemical performance.In this regard,the introduction of semiconductor-oxide materials and the approach of heterostructure formation by modulating energy bands to enhance ionic conduction acting as an electrolyte in fuel cell-device.Semiconductor(n-type;SnO_(2))plays a key role by introducing into p-type SrFe_(0.2)Ti_(0.8)O_(3-δ)(SFT)semiconductor perovskite materials to construct p-n heterojunction for high ionic conductivity.Therefore,two different composites of SFT and SnO_(2)are constructed by gluing p-and n-type SFT-SnO_(2),where the optimal composition of SFT-SnO_(2)(6∶4)heterostructure electrolyte-based fuel cell achieved excellent ionic conductivity 0.24 S cm^(-1)with power-output of 1004 mW cm^(-2)and high OCV 1.12 V at a low operational temperature of 500℃.The high power-output and significant ionic conductivity with durable operation of 54 h are accredited to SFT-SnO_(2)heterojunction formation including interfacial conduction assisted by a built-in electric field in fuel cell device.Moreover,the fuel conversion efficiency and considerable Faradaic efficiency reveal the compatibility of SFT-SnO_(2)heterostructure electrolyte and ruled-out short-circuiting issue.Further,the first principle calculation provides sufficient information on structure optimization and energy-band structure modulation of SFT-SnO_(2).This strategy will provide new insight into semiconductor-based fuel cell technology to design novel electrolytes.展开更多
Fe-Cr-Al alloys,owing to their absence of allotropic transformation,require multiple cycles of rolling and recrystallization annealing processes to achieve substantial grain refinement,ultimately leading to the attain...Fe-Cr-Al alloys,owing to their absence of allotropic transformation,require multiple cycles of rolling and recrystallization annealing processes to achieve substantial grain refinement,ultimately leading to the attainment of outstanding mechanical properties.However,the corresponding manufacturing costs will also increase greatly.In this work,we have proposed a new microstructural preparation process.Sim-ply using warm rolling for an ultra-coarse-grained Fe-Cr-Al alloy to introduce lamellar kink bands(KBs)into the matrix,the mechanical properties can be significantly improved.By using electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM),and combined with Schmid factor(SF)calculation,the formation mechanism of KBs has been revealed.When the slip plane and direction are nearly perpendicular to the loading force direction(LFD)during the continuous grain rotation,the dislo-cation wall will evolve into the KBs boundaries.Simultaneously,a huge orientation separation between the matrix and KBs will be produced.As strain continues to rise,KBs undergo a transformation,tran-sitioning from low-angle-grain boundaries(LAGBs)to high-angle-grain boundaries(HAGBs),occasionally adopting a configuration as coincident site lattice(CSL)boundaries with reduced interface energy.Re-sults of the tensile test,cyclic loading-unloading-reloading tensile test,and the strengthening calculation show that KBs can pronouncedly enhance the strength by their heterogeneous refinement on the original grains and hetero-deformation induced(HDI)strengthening effect from the dislocation density discrep-ancy between the matrix and internal KBs,the grains containing KBs(KBGs)and the grains without KBs(or KBs-free-grains,KFGs).The theoretical calculation value of the strengthening contribution from KBs on yield strength can be up to 225.5 MPa,with a minimum value exceeding 153 MPa.On the other hand,the ductility can be retained to some extent through stimulating the KBs boundary delamination mecha-nism.The present study provides a low-cost and feasible processing method for fabricating Fe-Cr-Al alloy with high strength and good ductility.展开更多
The Floquet technology,a powerful way to manipulate quantum states,is employed to drive sidebands transition under large detuning.Our results demonstrate that high fidelities over 99%can be achieved through optimizing...The Floquet technology,a powerful way to manipulate quantum states,is employed to drive sidebands transition under large detuning.Our results demonstrate that high fidelities over 99%can be achieved through optimizing suitable modulation frequencies under large detuning.We observe high-fidelity transitions within a high bandwidth by utilizing a single modulation frequency and reveal that this capability is due to the emergence of a flat-band structure in the bandwidth range.The key finding of high-fidelity sideband manipulation under large detuning is experimentally confirmed in nuclear magnetic resonance platform.Finally,we propose a new parallel sideband cooling scheme that enables simultaneous cooling of multiple motional modes.This approach improves the cooling rate compared to conventional schemes with fixed laser frequency and power,and eliminates the need for mode-specific addressing.Our Floquet parallel scheme is applicable to any harmonic oscillator system and is not limited by bandwidth in theory.展开更多
Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include ele...Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include elemental filling to regulate the band.However,the influence of the most electronegative fluorine on the CoSb_(3) band remains unclear.We carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling,lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites.展开更多
Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, mic...Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, microscopic research on this novel superconducting material is still lacking. Here, we utilize scanning tunneling microscopy/spectroscopy to uncover the superconductivity and surface structure of LaRu_(2)As_(2). Two distinct terminating surfaces are identified on the cleaved crystals, namely, the As surface and the La surface. Atomic missing line defects are observed on the La surface. Both surfaces exhibit a superconducting gap of ~ 1.0 me V. By employing quasiparticle interference techniques, we observe standing wave patterns near the line defects on the La atomic plane. These patterns are attributed to quasiparticle scattering from two electron type parabolic bands.展开更多
In DSP-based SerDes application,it is essential for AFE to implement a pre-ADC equalization to provide a better sig-nal for ADC and DSP.To meet the various equalization requirements of different channel and transmitte...In DSP-based SerDes application,it is essential for AFE to implement a pre-ADC equalization to provide a better sig-nal for ADC and DSP.To meet the various equalization requirements of different channel and transmitter configurations,this paper presents a 112 Gbps DSP-Based PAM4 SerDes receiver with a wide band equalization tuning AFE.The AFE is realized by implementing source degeneration transconductance,feedforward high-pass branch and inductive feedback peaking TIA.The AFE offers a flexible equalization gain tuning of up to 17.5 dB at Nyquist frequency without affecting the DC gain.With the pro-posed AFE,the receiver demonstrates eye opening after digital FIR equalization and achieves 6×10^(-9) BER with a 29.6 dB inser-tion loss channel.展开更多
Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is considered to be the most potential light-absorbing material to replace CuInGaSe_(2)(CIGS),but the actual photoelectric conversion efficiency of such cells is much lower than that of CIG...Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is considered to be the most potential light-absorbing material to replace CuInGaSe_(2)(CIGS),but the actual photoelectric conversion efficiency of such cells is much lower than that of CIGS.One of the reasons is the high recombination rate of carriers at the interface.In this paper,in order to reduce the carrier recombination,a new solar cell structure with double absorber layers of Al-doped ZnO(AZO)/intrinsic(i)-ZnO/CdS/CZTS_(x1)Se_(1−x1)(CZTSSe_(1))/CZTS_(x2)Se_(1−x2)(CZTSSe_(2))/Mo was proposed,and the optimal conduction band offsets(CBOs)of CdS/CZTSSe_(1) interface and CZTSSe_(1)/CZTSSe_(2) interface were determined by changing the S ratio in CZTSSe_(1) and CZTSSe_(2),and the effect of thickness of CZTSSe_(1) on the performance of the cell was studied.The efficiencies of the optimized single and double absorber layers reached 17.97%and 23.4%,respectively.Compared with the single absorber layer structure,the proposed structure with double absorber layers has better cell performance.展开更多
A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generali...A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generalized differential quadrature rule(GDQR)method combined with the Bloch theorem is used to calculate the vibration band gaps of the structure.Results are verified by the forced vibration responses obtained using the GDQR method.Results indicate that the first two band gaps of the fluid-conveying pipe with periodic material arrangement can get close to each other and move to low frequency regions by changing the length of cantilever pipes.For high fluid velocity values in which the first band gap starts from zero frequency,since the second band is very close to the first band,this periodic structure can be used for vibration reduction over a wide band gap starting from zero frequency.Based on these results,it can be concluded that instead of increasing the total size of the periodic structure,these periodic arrays of cantilever pipes can be implemented to create a wide ultra-low-frequency band gap.Finally,verification of the GDQR method shows that it can be used as a precise numerical method for vibration analysis of the structures such as fluid-conveying pipes and moving belts.展开更多
In Hyperspectral Imaging(HSI),the detrimental influence of noise and distortions on data quality is profound,which has severely affected the following-on analytics and decisionmaking such as land mapping.This study pr...In Hyperspectral Imaging(HSI),the detrimental influence of noise and distortions on data quality is profound,which has severely affected the following-on analytics and decisionmaking such as land mapping.This study presents an innovative framework for assessing HSI band quality and reconstructing the low-quality bands,based on the Prophet model.By introducing a comprehensive quality metric to start,the authors approach factors in both spatial and spectral characteristics across local and global scales.This metric effectively captures the intricate noise and distortions inherent in the HSI data.Subsequently,the authors employ the Prophet model to forecast information within the low-quality bands,leveraging insights from neighbouring high-quality bands.To validate the effectiveness of the authors’proposed model,extensive experiments on three publicly available uncorrected datasets are conducted.In a head-to-head comparison,the framework against six state-ofthe-art band reconstruction algorithms including three spectral methods,two spatialspectral methods and one deep learning method is benchmarked.The authors’experiments also delve into strategies for band selection based on quality metrics and the quality evaluation of the reconstructed bands.In addition,the authors assess the classification accuracy utilising these reconstructed bands.In various experiments,the results consistently affirm the efficacy of the authors’method in HSI quality assessment and band reconstruction.Notably,the authors’approach obviates the need for manually prefiltering of noisy bands.This comprehensive framework holds promise in addressing HSI data quality concerns whilst enhancing the overall utility of HSI.展开更多
The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices...The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices. In this work, we propose the concept of a Lieb electride, where the non-bound electrons gather at the middle edges,behaving as the quasi-atoms of a Lieb lattice, enabling the emergence of flat bands. Using crystal structure prediction method MAGUS and first-principles calculations, we predict a stable candidate, Ca_(2)I, at ambient pressure. Distinct from conventional electrides with localized electrons at cavity centers, Ca_(2)I features interstitial electrons situated at cavity edges. The resultant flat bands lie close to the Fermi level, giving rise to a pronounced peak in the density of states and leading to Stoner-type ferromagnetism. With increasing pressures, we observe quantum phase transitions from ferromagnetic to non-magnetic and finally to antiferromagnetic orders in Ca_(2)I.Intriguingly, superconductivity emerges in the antiferromagnetic region, suggesting potential competition between these correlated states. Our study not only extends the concepts of electrides but also provides a novel strategy for realizing Lieb lattices through non-bound electrons. This work establishes Ca_(2)I as a promising platform for exploring flat-band physics and correlated electronic states, opening avenues for novel quantum phenomena in electride-based materials.展开更多
Refractory high-entropy alloys(RHEAs)exhibit outstanding strength at room temperature,but their high-temperature applications are hindered by severe strain-softening.Here,we report slip-band-driven dy-namic recrystall...Refractory high-entropy alloys(RHEAs)exhibit outstanding strength at room temperature,but their high-temperature applications are hindered by severe strain-softening.Here,we report slip-band-driven dy-namic recrystallization to enhance the high-temperature strain hardening of HfNbTaTiZr RHEA.By intro-ducing partial lattice defects through hot forging,we increase the nucleation sites for dynamic recrys-tallization during subsequent thermomechanical deformation,thus suppressing the strain-softening be-havior.We reveal that the high-temperature deformation is governed by the formation of heterogeneous bimodal grains along slip bands,which effectively constrain dislocation motion and improve strength,while microbands prevent premature failure.The fracture mode also changes from ductile to mixed to cleavage-dominated with increasing temperature.Our results demonstrate a simple and effective method for overcoming high-temperature strain-softening for BCC high entropy alloys.展开更多
基金supported by the program for National Natural Science Foundation of China (Nos. 52174173, 52274188, and 52104190)the Joint Funds of the National Natural Science Foundation of China (No. U24A2091)+1 种基金The Natural Science Foundation of Henan Polytechnic University (No. B2021-2)Double FirstClass Initiative of Safety and Energy Engineering (Henan Polytechnic University) (Nos. AQ20240703 and AQ20230304)。
文摘Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.
基金The National Natural Science Foundation of China(No.12002086)。
文摘To analyze the band gap characteristics of phononic crystals,a two-dimensional phononic crystal plate model with an elastic foundation was first established.The plane wave expansion method was used to compute the dispersion curves of this phononic crystal model,and the results were compared with those from the finite element method to verify their accuracy.Subsequently,a parameter study explored the effects of the elastic foundation coeffi-cient and coverage ratio on the band gap.The results indicate that as the coverage ratio of the elastic foundation increases,the band gap significantly expands,reaching its maximum value at 100%coverage.Additionally,as the elastic foundation stiffness increases,the band gap gradually widens and converges toward fixed boundary conditions.The study also investigated the band gap of phononic crystal plates with defects,finding that the vibrational energy concentrates at the defect unit cell.Furthermore,the defect band frequency can be effectively modulated by adjusting the coefficient of the elastic foundation,providing a theoretical basis for achieving efficient energy conversion.
基金supported in part by the National Natural Science Foundation of China(Grant No.12432001)Natural Science Foundation of Hunan Province(Grant Nos.2023JJ60527,2023JJ30152,and 2023JJ30259)the Natural Science Foundation of Changsha(KQ2202133).
文摘This study investigates the nonlinear resonance responses of suspended cables subjected to multi-frequency excitations and time-delayed feedback.Two specific combinations and simultaneous resonances are selected for detailed examination.Initially,utilizing Hamilton’s variational principle,a nonlinear vibration control model of suspended cables under multi-frequency excitations and longitudinal time-delayed velocity feedback is developed,and the Galerkin method is employed to obtain the discrete model.Subsequently,focusing solely on single-mode discretization,analytical solutions for the two simultaneous resonances are derived using the method of multiple scales.The frequency response equations are derived,and the stability analysis is presented for two simultaneous resonance cases.The results demonstrate that suspended cables exhibit complex nonlinearity under multi-frequency excitations.Multiple solutions under multi-frequency excitation can be distinguished through the frequency–response and the detuning-phase curves.By adjusting the control gain and time delay,the resonance range,response amplitude,and phase of suspended cables can be modified.
文摘The advancement of imaging resolution has made the impact of multi-frequency composite jitter in satellite platforms on non-collinear time delay and integration(TDI)charge-coupled device(CCD)imaging systems increasingly critical.Moreover,the accuracy of jitter detection is constrained by the limited inter-chip overlap region inherent to non-collinear TDI CCDs.To address these challenges,a multi-frequency jitter detection method is proposed,achieving sub-pixel level error extraction.Furthermore,a multi-frequency jitter fitting approach utilizing a scale-adjustable sliding window is introduced.For composite multi-frequency jitter,spectral analysis decomposes the relative jitter error curve,while the scale-adjustable sliding window enables frequency-division fitting and modeling.Validation experiments using Gaofen-8(GF-8)remote sensing satellite imagery detected jitter at 0.65,20,and 100 Hz in the cross-track direction and at 0.5,100,and 120 Hz in the along-track direction,demonstrating the method’s precision in detecting platform jitter at sub-pixel accuracy(<0.2 pixels)and its efficacy in fitting and modeling for non-collinear TDI CCD imaging systems subject to multi-frequency jitter.
基金Project supported by the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2021B1515130007)the National Natural Science Foundation of China (Grant Nos. U21A20432 and 52273077)+1 种基金the National Key Research and Development Program of China (Grant No. 2022YFA1403800)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB33000000)。
文摘Flat electronic bands in condensed matter provide a rich avenue for exploring novel quantum phenomena. Here, we report an optical spectroscopy study of a topological hourglass semimetal Nb_(3)SiTe_(6) with the electric field of the incident light parallel to its crystalline ab-plane. The ab-plane optical conductivity spectra of Nb_(3)SiTe_(6) single crystals exhibit a remarkable peak-like feature around 1.20 eV, which is mainly contributed by the direct optical transitions between the two ab-initio-calculation-derived flat bands along the momentum direction Z–U. Our results pave the way for investigating exotic quantum phenomena based on the flat bands in topological hourglass semimetals.
文摘BACKGROUND The generation of intrabony defects due to the iatrogenic use of elastic bands is an undesirable situation that can result in persistent gingival inflammation with subsequent bone degradation,thus ultimately leading to tooth loss.CASE SUMMARY This clinical case involved a 27-year-old male patient who complained of persistent inflammation and bleeding in the upper anterior region of the gums,despite having undergone dental cleaning for at least 4 years.The dental and medical history indicated the use of removable orthodontic appliances for 8 years,after which braces were placed for 2 years.The intraoral evaluation revealed inflammation and localized suppuration in teeth 11 and 12.Measurements of 2-7 mm for probing depth and 1-5 mm for clinical attachment loss were detected,and combined bone loss was observed via radiographs.Based on the clinical and radiographic findings,localized stage III,grade C periodontitis was diagnosed.During subgingival debridement,two elastic bands emerged around the involved teeth.The bone defects persisted;therefore,they were surgically addressed using a papilla preservation flap and guided tissue regeneration(GTR).CONCLUSION The use of elastic bands of various sizes and elasticities is often essential in multiple orthodontic treatments.However,it is crucial to perform a thorough check-up for each patient during treatment and at the end of treatment to remove any remaining residue of resin,metal bands,or orthodontic bands.Additionally,it is imperative to inform the patients of the importance of attending their follow-up appointments.The use of elastic bands in orthodontics requires special care;moreover,GTR is a management option for intrabony defects associated with the iatrogenic use of bands.
基金supported by the National Nature Science Foundation of China[Grant Nos.92365204 and 12274298(Z.K.Liu)]the National Key R&D program of China[Grant No.2022YFA1604400/03(Z.K.Liu)]Zhangjiang Laboratory(Y.M.Zhang).The authors thank BL02B at the Shanghai Synchrotron Radiation Facility supported by the National Natural Science Foundation of China(Contract No.11227902).
文摘Fe-based superconductors represent a fascinating class of materials,extensively studied for their complex interplay of superconductivity,magnetism,spin density waves,and nematicity,along with the interactions among these orders.An intriguing yet unexplained phenomenon observed in Fe-based superconductors is the emergence of superconductivity below 25K in the non-superconducting parent compound SrFe_(2)As_(2)following exposure to water at its surface.In this study,we employed in situ angle-resolved photoemission spectroscopy and low-energy electron diffraction to meticulously examine the electronic structure evolution of SrFe_(2)As_(2)upon in situ water dosing.Our findings indicate that water dosing markedly attenuates the spin density wave phase and surface Sr reconstruction while preserving the nematic order in SrFe_(2)As_(2).Furthermore,we detected an enhancement in the spectral weight of bands near the Fermi level.Our observations highlight the critical role of the intricate interplay among various orders induced by water dosing,which effectively modifies the band structure and favors the emergence of superconductivity in SrFe_(2)As_(2).
基金supported by the Ministry of Science and Technology(Grant No.2022YFA1403901)the National Natural Science Foundation of China(Grant Nos.12494594,11888101,12174428,and 12504192)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000)the New Cornerstone Investigator Program,the Chinese Academy of Sciences through the Youth Innovation Promotion Association(Grant No.2022YSBR-048)the Shanghai Science and Technology Innovation Action Plan(Grant No.24LZ1400800).
文摘Systems hosting flat bands offer a powerful platform for exploring strong correlation physics.Theoretically,topological degeneracy arising in systems with non-trivial topological orders on periodic manifolds of non-zero genus can generate ideal flat bands.However,experimental realization of such geometrically engineered systems is very difficult.In this work,we demonstrate that flat planes with strategically patterned hole defects can engineer ideal flat bands.We construct two families of models:singular flat band systems where degeneracy is stabilized by non-contractible loop excitations tied to hole defects and perfectly nested van Hove systems where degeneracy arises from line excitations in momentum space.These models circumvent the need for exotic manifolds while retaining the essential features of topological flat bands.By directly linking defect engineering to degeneracy mechanisms,our results establish a scalable framework for experimentally accessible flat band design.
基金the National Natural Science Foundation of China(U2241245,91960202 and 52271012)the National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(6142902220301)+2 种基金the Aeronautical Science Foundation of China(2022Z053092001)the Shanghai Engineering Research Center of High-Performance Medical Device Materials(20DZ2255500)the Opening Project of National Key Laboratory of Shock Wave and Detonation Physics(2022JCJQLB05702).
文摘The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics simulation.Remarkably,non-uniform plastic deformation was observed in the sample.At high strain rates,amorphization occurred near the edge of the contact region where severe shear strain induced a large number of stacking faults(SFs)and dislocations.In contrast,the central part of the contact region underwent less deformation with significantly fewer dislocations.Moreover,instead of amorphization by consuming SFs and dislocations,there was a gradual increase in the density of dislocations and SFs during the process of amorphization.These local amorphous regions eventually grew into shear bands.
基金supported by the National Natural Science Foundation of China(Grant No.32250410309 and 52105582)Natural Science Foundation of Guangdong Province(Grant No.2022A1515010894 and 2022B0303040002)+1 种基金Fundamental Research Foundation of Shenzhen(JCYJ20210324095210030 and JCYJ20220818095810023)Shenzhen-Hong Kong-Macao S&T Program(Category C:SGDX20210823103200004)
文摘Extending the ionic conductivity is the pre-requisite of electrolytes in fuel cell technology for high-electrochemical performance.In this regard,the introduction of semiconductor-oxide materials and the approach of heterostructure formation by modulating energy bands to enhance ionic conduction acting as an electrolyte in fuel cell-device.Semiconductor(n-type;SnO_(2))plays a key role by introducing into p-type SrFe_(0.2)Ti_(0.8)O_(3-δ)(SFT)semiconductor perovskite materials to construct p-n heterojunction for high ionic conductivity.Therefore,two different composites of SFT and SnO_(2)are constructed by gluing p-and n-type SFT-SnO_(2),where the optimal composition of SFT-SnO_(2)(6∶4)heterostructure electrolyte-based fuel cell achieved excellent ionic conductivity 0.24 S cm^(-1)with power-output of 1004 mW cm^(-2)and high OCV 1.12 V at a low operational temperature of 500℃.The high power-output and significant ionic conductivity with durable operation of 54 h are accredited to SFT-SnO_(2)heterojunction formation including interfacial conduction assisted by a built-in electric field in fuel cell device.Moreover,the fuel conversion efficiency and considerable Faradaic efficiency reveal the compatibility of SFT-SnO_(2)heterostructure electrolyte and ruled-out short-circuiting issue.Further,the first principle calculation provides sufficient information on structure optimization and energy-band structure modulation of SFT-SnO_(2).This strategy will provide new insight into semiconductor-based fuel cell technology to design novel electrolytes.
基金financially supported by the National Natural Science Foundation of China(No.U1867201)Key Project of Nuclear Safety and Advanced Nuclear Technology(No.2019YFB1901002)“the Project supported by State Key Laboratory of Powder Metallurgy”,Central South University,Changsha,China。
文摘Fe-Cr-Al alloys,owing to their absence of allotropic transformation,require multiple cycles of rolling and recrystallization annealing processes to achieve substantial grain refinement,ultimately leading to the attainment of outstanding mechanical properties.However,the corresponding manufacturing costs will also increase greatly.In this work,we have proposed a new microstructural preparation process.Sim-ply using warm rolling for an ultra-coarse-grained Fe-Cr-Al alloy to introduce lamellar kink bands(KBs)into the matrix,the mechanical properties can be significantly improved.By using electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM),and combined with Schmid factor(SF)calculation,the formation mechanism of KBs has been revealed.When the slip plane and direction are nearly perpendicular to the loading force direction(LFD)during the continuous grain rotation,the dislo-cation wall will evolve into the KBs boundaries.Simultaneously,a huge orientation separation between the matrix and KBs will be produced.As strain continues to rise,KBs undergo a transformation,tran-sitioning from low-angle-grain boundaries(LAGBs)to high-angle-grain boundaries(HAGBs),occasionally adopting a configuration as coincident site lattice(CSL)boundaries with reduced interface energy.Re-sults of the tensile test,cyclic loading-unloading-reloading tensile test,and the strengthening calculation show that KBs can pronouncedly enhance the strength by their heterogeneous refinement on the original grains and hetero-deformation induced(HDI)strengthening effect from the dislocation density discrep-ancy between the matrix and internal KBs,the grains containing KBs(KBGs)and the grains without KBs(or KBs-free-grains,KFGs).The theoretical calculation value of the strengthening contribution from KBs on yield strength can be up to 225.5 MPa,with a minimum value exceeding 153 MPa.On the other hand,the ductility can be retained to some extent through stimulating the KBs boundary delamination mecha-nism.The present study provides a low-cost and feasible processing method for fabricating Fe-Cr-Al alloy with high strength and good ductility.
基金supported by the National Natural Science Foundation of China(Grant Nos.11904402,12174447,12074433,12004430,and 12174448)。
文摘The Floquet technology,a powerful way to manipulate quantum states,is employed to drive sidebands transition under large detuning.Our results demonstrate that high fidelities over 99%can be achieved through optimizing suitable modulation frequencies under large detuning.We observe high-fidelity transitions within a high bandwidth by utilizing a single modulation frequency and reveal that this capability is due to the emergence of a flat-band structure in the bandwidth range.The key finding of high-fidelity sideband manipulation under large detuning is experimentally confirmed in nuclear magnetic resonance platform.Finally,we propose a new parallel sideband cooling scheme that enables simultaneous cooling of multiple motional modes.This approach improves the cooling rate compared to conventional schemes with fixed laser frequency and power,and eliminates the need for mode-specific addressing.Our Floquet parallel scheme is applicable to any harmonic oscillator system and is not limited by bandwidth in theory.
基金supported by the National Natural Science Foundation of China (Grant Nos.52171220,92163212,and 92163119)the Research Funding of Wuhan Polytechnic University (Grant No.2022RZ059)the National Innovation and Entrepreneurship Training Program for College Students (Grant No.S202310497202)。
文摘Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include elemental filling to regulate the band.However,the influence of the most electronegative fluorine on the CoSb_(3) band remains unclear.We carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling,lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62488201 and 52072401)the National Key R&D Program of China(Grant No.2019YFA0308500)+1 种基金the Chinese Academy of Sciences(Grant No.YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, microscopic research on this novel superconducting material is still lacking. Here, we utilize scanning tunneling microscopy/spectroscopy to uncover the superconductivity and surface structure of LaRu_(2)As_(2). Two distinct terminating surfaces are identified on the cleaved crystals, namely, the As surface and the La surface. Atomic missing line defects are observed on the La surface. Both surfaces exhibit a superconducting gap of ~ 1.0 me V. By employing quasiparticle interference techniques, we observe standing wave patterns near the line defects on the La atomic plane. These patterns are attributed to quasiparticle scattering from two electron type parabolic bands.
基金supported by National Key R&D Program of China No.2022YFB2803401.
文摘In DSP-based SerDes application,it is essential for AFE to implement a pre-ADC equalization to provide a better sig-nal for ADC and DSP.To meet the various equalization requirements of different channel and transmitter configurations,this paper presents a 112 Gbps DSP-Based PAM4 SerDes receiver with a wide band equalization tuning AFE.The AFE is realized by implementing source degeneration transconductance,feedforward high-pass branch and inductive feedback peaking TIA.The AFE offers a flexible equalization gain tuning of up to 17.5 dB at Nyquist frequency without affecting the DC gain.With the pro-posed AFE,the receiver demonstrates eye opening after digital FIR equalization and achieves 6×10^(-9) BER with a 29.6 dB inser-tion loss channel.
基金supported by the Science and Technology Innovation Development Program(No.70304901).
文摘Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is considered to be the most potential light-absorbing material to replace CuInGaSe_(2)(CIGS),but the actual photoelectric conversion efficiency of such cells is much lower than that of CIGS.One of the reasons is the high recombination rate of carriers at the interface.In this paper,in order to reduce the carrier recombination,a new solar cell structure with double absorber layers of Al-doped ZnO(AZO)/intrinsic(i)-ZnO/CdS/CZTS_(x1)Se_(1−x1)(CZTSSe_(1))/CZTS_(x2)Se_(1−x2)(CZTSSe_(2))/Mo was proposed,and the optimal conduction band offsets(CBOs)of CdS/CZTSSe_(1) interface and CZTSSe_(1)/CZTSSe_(2) interface were determined by changing the S ratio in CZTSSe_(1) and CZTSSe_(2),and the effect of thickness of CZTSSe_(1) on the performance of the cell was studied.The efficiencies of the optimized single and double absorber layers reached 17.97%and 23.4%,respectively.Compared with the single absorber layer structure,the proposed structure with double absorber layers has better cell performance.
文摘A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generalized differential quadrature rule(GDQR)method combined with the Bloch theorem is used to calculate the vibration band gaps of the structure.Results are verified by the forced vibration responses obtained using the GDQR method.Results indicate that the first two band gaps of the fluid-conveying pipe with periodic material arrangement can get close to each other and move to low frequency regions by changing the length of cantilever pipes.For high fluid velocity values in which the first band gap starts from zero frequency,since the second band is very close to the first band,this periodic structure can be used for vibration reduction over a wide band gap starting from zero frequency.Based on these results,it can be concluded that instead of increasing the total size of the periodic structure,these periodic arrays of cantilever pipes can be implemented to create a wide ultra-low-frequency band gap.Finally,verification of the GDQR method shows that it can be used as a precise numerical method for vibration analysis of the structures such as fluid-conveying pipes and moving belts.
基金National Natural Science Foundation Major Project of China,Grant/Award Number:42192580Guangdong Province Key Construction Discipline Scientific Research Ability Promotion Project,Grant/Award Number:2022ZDJS015。
文摘In Hyperspectral Imaging(HSI),the detrimental influence of noise and distortions on data quality is profound,which has severely affected the following-on analytics and decisionmaking such as land mapping.This study presents an innovative framework for assessing HSI band quality and reconstructing the low-quality bands,based on the Prophet model.By introducing a comprehensive quality metric to start,the authors approach factors in both spatial and spectral characteristics across local and global scales.This metric effectively captures the intricate noise and distortions inherent in the HSI data.Subsequently,the authors employ the Prophet model to forecast information within the low-quality bands,leveraging insights from neighbouring high-quality bands.To validate the effectiveness of the authors’proposed model,extensive experiments on three publicly available uncorrected datasets are conducted.In a head-to-head comparison,the framework against six state-ofthe-art band reconstruction algorithms including three spectral methods,two spatialspectral methods and one deep learning method is benchmarked.The authors’experiments also delve into strategies for band selection based on quality metrics and the quality evaluation of the reconstructed bands.In addition,the authors assess the classification accuracy utilising these reconstructed bands.In various experiments,the results consistently affirm the efficacy of the authors’method in HSI quality assessment and band reconstruction.Notably,the authors’approach obviates the need for manually prefiltering of noisy bands.This comprehensive framework holds promise in addressing HSI data quality concerns whilst enhancing the overall utility of HSI.
基金supported by the National Natural Science Foundation of China(Grant Nos.12125404,T2495231,123B2049,and 12204138)the National Key R&D Program of China(Grant No.2022YFA1403201)+7 种基金the Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0607000)the Basic Research Program of Jiangsu (Grant Nos.BK20233001 and BK20241253)the Jiangsu Funding Program for Excellent Postdoctoral Talent (Grant Nos.2024ZB002,2024ZB075,2025ZB440 and2025ZB852)the China Postdoctoral Science Foundation (Grant No.2025M773331)the Postdoctoral Fellowship Program of CPSF (Grant No.GZC20240695 and GZC20252202)the AI&AI for Science Program of Nanjing UniversityArtificial Intelligence and Quantum physics (AIQ) program of Nanjing Universitythe Fundamental Research Funds for the Central Universities。
文摘The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices. In this work, we propose the concept of a Lieb electride, where the non-bound electrons gather at the middle edges,behaving as the quasi-atoms of a Lieb lattice, enabling the emergence of flat bands. Using crystal structure prediction method MAGUS and first-principles calculations, we predict a stable candidate, Ca_(2)I, at ambient pressure. Distinct from conventional electrides with localized electrons at cavity centers, Ca_(2)I features interstitial electrons situated at cavity edges. The resultant flat bands lie close to the Fermi level, giving rise to a pronounced peak in the density of states and leading to Stoner-type ferromagnetism. With increasing pressures, we observe quantum phase transitions from ferromagnetic to non-magnetic and finally to antiferromagnetic orders in Ca_(2)I.Intriguingly, superconductivity emerges in the antiferromagnetic region, suggesting potential competition between these correlated states. Our study not only extends the concepts of electrides but also provides a novel strategy for realizing Lieb lattices through non-bound electrons. This work establishes Ca_(2)I as a promising platform for exploring flat-band physics and correlated electronic states, opening avenues for novel quantum phenomena in electride-based materials.
基金supported by the Aviation Foundation(No.2023Z0530S6004)Program 173(No.2020-JCIQ-ZD-186-01)+4 种基金the Space Utilization System of China Manned Space Engineering(No.KJZ-YY-NCL08)the Shanghai“Super Postdoc”Incentive Program(No.2023314)the National High-end Foreign Experts Introduction Program(No.G2023014006)the Zhenjiang International Science and Technology Cooperation Program(No.GJ2023011)the Jiangsu University(High-tech ship)Collaborative Innovation Center Program(No.XTCX202401).
文摘Refractory high-entropy alloys(RHEAs)exhibit outstanding strength at room temperature,but their high-temperature applications are hindered by severe strain-softening.Here,we report slip-band-driven dy-namic recrystallization to enhance the high-temperature strain hardening of HfNbTaTiZr RHEA.By intro-ducing partial lattice defects through hot forging,we increase the nucleation sites for dynamic recrys-tallization during subsequent thermomechanical deformation,thus suppressing the strain-softening be-havior.We reveal that the high-temperature deformation is governed by the formation of heterogeneous bimodal grains along slip bands,which effectively constrain dislocation motion and improve strength,while microbands prevent premature failure.The fracture mode also changes from ductile to mixed to cleavage-dominated with increasing temperature.Our results demonstrate a simple and effective method for overcoming high-temperature strain-softening for BCC high entropy alloys.
