In today's era of continuous advancement in materials science,the properties of materials are constantly being enhanced,and their application fields are also expanding continuously.SAF(Super Absorbent Fiber),one s...In today's era of continuous advancement in materials science,the properties of materials are constantly being enhanced,and their application fields are also expanding continuously.SAF(Super Absorbent Fiber),one such material,stands out.Compared to traditional SAP(Super Absorbent Polymer),SAF boasts a unique fibrous form and exceptional performance,presenting broad application prospects.展开更多
This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered ...This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered damping amplifier friction vibration absorbers(LDAFVAs)for controlling the structural vibrations and addressing the limitations of conventional tuned mass dampers(TMDs)and frictiontuned mass dampers(FTMDs).The closed-form analytical solution for the optimized design parameters is obtained using the H_(2)and H_(∞)optimization approaches.The efficiency of the recently established closed-form equations for the optimal design parameters is confirmed by the analytical examination.The closed form formulas for the dynamic responses of the main structure and the vibration absorbers are derived using the transfer matrix formulations.The foundation is provided by the harmonic and random-white noise excitations.Moreover,the effectiveness of the innovative dampers has been validated through numerical analysis.The optimal DAFVAs,CDAFVAs,NDAFVAs,and LDAFVAs exhibit at least 30%lower vibration reduction capacity compared with the optimal TMD.To demonstrate the effectiveness of the damping amplification mechanism,the novel absorbers are compared with a conventional FTMD.The results show that the optimized novel absorbers achieve at least 91%greater vibration reduction than the FTMD.These results show how the suggested designs might strengthen the structure's resilience to dynamic loads.展开更多
Optically transparent microwave absorbers and multi-band stealth have extensive potential applications in military defense and wireless communication fields, and thus have attracted considerable attention. So far,most...Optically transparent microwave absorbers and multi-band stealth have extensive potential applications in military defense and wireless communication fields, and thus have attracted considerable attention. So far,most related work is based on inorganic transparent conductive metasurfaces. In this paper, we proposed and experimentally demonstrated a flexible, broadband and optically transparent microwave absorber using an organic metasurface. The metasurface absorber is composed of a sandwich structure, in which electric resonances and magnetic resonances are induced resulting in broadband absorption. A spraying process was developed to prepare this metasurface absorber. Both simulations and experiment show that this metasurface has broadband microwave absorption and good optical transparency. We further found that by using a multi-layer structure, visible, radar,and infrared stealth(multi-band stealth) can be achieved simultaneously. With the advantages of excellent foldability and low cost, the proposed metasurfaces may have applications in military and wireless communication fields.展开更多
In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
Due to their unique physical properties,nonlinear materials are gradually demonstrating significant potential in the field of optics.Gold nanoparticles supported on carbon black(Au/CB),possessing low loss and high non...Due to their unique physical properties,nonlinear materials are gradually demonstrating significant potential in the field of optics.Gold nanoparticles supported on carbon black(Au/CB),possessing low loss and high nonlinear characteristics,serve as an excellent material for saturable absorber(SA) in ultrafast fiber lasers.In this study,we investigated the performance of Au/CB material and designed an ultrafast fiber laser based on Au/CB SA,successfully observing stable fundamental mode-locking and pulse bunch phenomena.Specifically,when the fiber laser operates in fundamental mode-locking state,the center wavelength of optical spectrum is 1 558.82 nm,with a 3 dB bandwidth of 2.26 nm.Additionally,to investigate the evolution of real-time spectra,the dispersive Fourier transform(DFT) technology is employed.On the other hand,the pulse bunch emitted by the laser is actually composed of numerous random sub-pulses,exhibiting high-energy characteristics.The number of sub-pulses increases with the increase of pump power.These findings contribute to further exploring the properties of Au/CB material and reveal its potential applications in ultrafast optics.展开更多
In the field of broadband metamaterial absorbers,most research efforts have focused on optimizing the resonant layers and designing multi-layer structures,but relatively little attention has been paid to the dielectri...In the field of broadband metamaterial absorbers,most research efforts have focused on optimizing the resonant layers and designing multi-layer structures,but relatively little attention has been paid to the dielectric layers themselves.This paper proposed a method using carbonyl iron powder to modify the dielectric layer.This method significantly enhances the electromagnetic wave attenuation capability of the dielectric layer with the X-band range for metamaterial absorbers.A broadband absorber with a reflection loss(RL)of less than-10 dB within the frequency range of 4.98-18 GHz and covering the C,X,and Ku band was designed.This work analyzed the surface current distribution and the power loss distribution to elucidate the absorption mechanism of the absorber.It was found that the modified dielectric layer accounted for more than 30%of the total loss in the 2-18 GHz frequency band,and the effective absorption bandwidth(RL≤-10 dB)was almost twice that of the unmodified dielectric layer.This enhancement in absorption bandwidth is attributed to the introduction of a new electromagnetic wave loss mechanism by carbonyl iron powder.Meanwhile,the absorber exhibited good angular stability,maintaining at least 80%absorption(RL≤-7 dB)in the 7.0-18.0 GHz range even when the incident angle was increased to 60°.The experimental results showed that the measured results matched the simulation results well.Furthermore,compared with other methods for broadening the absorption bandwidth,the metamaterial absorber obtained by this method offers several advantages,including wideband absorption,thin profile,and a simple manufacturing process.This approach provides a new and promising direction for the design of broadband absorbers.展开更多
In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in ...In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in projects susceptible to dynamic shear loads.In laboratory experiments,fully-grouted bolts and energy-absorbing bolts were used as research objects,and artificial rock specimens with rough joints were fabricated to analyze the shear characteristics and damage mechanisms of bolted rock joints under cyclic shear conditions and different shear velocities.The results showed that as the shear rate increased,the shear strength of bolted rock joint specimens decreased.Degradation of asperities resulted in no obvious peak shear stress in the specimens.Energy-absorbing bolts exhibited greater deformation capacity,with significant necking phenomena and the ability to withstand larger shear displacements.In contrast,fully-grouted bolts,which have threaded surfaces that provide higher bonding performance,exhibited a reduced capacity for plastic deformation and were prone to breaking under smaller shear displacements.Although the shear stiffness of specimens reinforced by energy-absorbing bolts was slightly lower than that of fully-grouted bolt specimens,they demonstrated greater stability under various shear rates.The absorbed shear energy showed that energy-absorbing bolts had superior coordinated deformation capabilities,thus exhibiting greater absorbed shear energy than fully-grouted bolts.Overall,fully-grouted bolts are more suitable for projects requiring higher rock shear strength and overall stiffness.In contrast,energy-absorbing bolts are more suitable for coping with dynamic or fluctuating load conditions to maintain the relative stability of jointed rock masses.展开更多
Gels and conductive polymer composites,including hydrogen bonds(HBs),have emerged as promising materials for electro-magnetic wave(EMW)absorption across various applications.However,the relationship between conduction...Gels and conductive polymer composites,including hydrogen bonds(HBs),have emerged as promising materials for electro-magnetic wave(EMW)absorption across various applications.However,the relationship between conduction loss in EMW-absorbing materials and charge transfer in HB remains to be fully understood.In this study,we developed a series of deep eutectic gels to fine-tune the quantity of HB by adjusting the molar ratio of choline chloride(ChCl)and ethylene glycol(EG).Owing to the unique properties of deep eutectic gels,the effects of magnetic loss and polarization loss on EMW attenuation can be disregarded.Our results indicate that the quantity of HB initially increases and then decreases with the introduction of EG,with HB-induced conductive loss following similar pat-terns.At a ChCl and EG molar ratio of 2.4,the gel labeled G22-CE2.4 exhibited the best EMW absorption performance,characterized by an effective absorption bandwidth of 8.50 GHz and a thickness of 2.54 mm.This superior performance is attributed to the synergistic ef-fects of excellent conductive loss and impedance matching generated by the optimal number of HB.This work elucidates the role of HB in dielectric loss for the first time and provides valuable insights into the optimal design of supramolecular polymer absorbers.展开更多
Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and control-lable preparation of metal oxide/carbon-based composite microwave absorption materials.In t...Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and control-lable preparation of metal oxide/carbon-based composite microwave absorption materials.In this study,a flake-like nickel cobaltate/re-duced graphene oxide/melamine-derived carbon foam(FNC/RGO/MDCF)was successfully fabricated through a combination of solvo-thermal treatment and high-temperature pyrolysis.Results indicated that RGO was evenly distributed in the MDCF skeleton,providing ef-fective support for the load growth of FNC on its surface.Sample S3,the FNC/RGO/MDCF composite prepared by solvothermal method for 16 h,exhibited a minimum reflection loss(RL_(min))of-66.44 dB at a thickness of 2.29 mm.When the thickness was reduced to 1.50 mm,the optimal effective absorption bandwidth was 3.84 GHz.Analysis of the absorption mechanism of FNC/RGO/MDCF revealed that its excellent absorption performance was primarily attributed to the combined effects of conduction loss,multiple reflection,scattering,in-terface polarization,and dipole polarization.展开更多
In this paper,a conventional soliton(CS)mode-locked erbium-doped fiber(EDF)laser was de-veloped using MAX phase material(MAX-PM)Nb_(4)AlC_(3)as a saturable absorber(SA).First,the liquid phase exfoliation(LPE)method wa...In this paper,a conventional soliton(CS)mode-locked erbium-doped fiber(EDF)laser was de-veloped using MAX phase material(MAX-PM)Nb_(4)AlC_(3)as a saturable absorber(SA).First,the liquid phase exfoliation(LPE)method was utilized to prepare Nb_(4)AlC_(3)nanosheets,and then a piece of tapered fiber was adopted to fabricate Nb_(4)AlC_(3)-SA.It was found that the saturation intensity and modulation depth of the Nb_(4)AlC_(3)-SA are 2.02 MW/cm^(2)and 1.88%.Based on the Nb_(4)AlC_(3)-SA,a conventional soliton(CS)mode-locked EDF laser was achieved.The central wavelength,pulse duration,and pulse repetition rate were found to be 1565.65 nm,615.37 fs,and 24.63 MHz,respectively.The performance is competitive and particularly superior in terms of pulse duration.This study fully confirms that Nb_(4)AlC_(3)possesses marvellous nonlinear saturable absorption properties and opens new possibilities for further research on air-stable ultrafast photon-ic devices.展开更多
Color plays an important role in the daily chemical product market,and transparent packaging of daily chemical products are loved by consumers,but it is difficult to avoid fading,discoloration or photodegradation of t...Color plays an important role in the daily chemical product market,and transparent packaging of daily chemical products are loved by consumers,but it is difficult to avoid fading,discoloration or photodegradation of the inner material of the product.UV light is a major contributor to colorant fading,which can affect color stability by damaging chromogenic groups and producing free radicals.In view of this,the combination of four ultraviolet absorbers DHHB,OS,OMC,and MCE was investigated,and the photostability of five common colorants in cosmetics was studied.After 28 days of photostability test,the pigment preservation rate was analyzed,and the results showed that 0.1%of the UV absorber compound could have a certain protective effect on the colorant,and 0.5%of the compound could significantly improve the photostability of the colorant.Adding ultraviolet absorbers to daily chemical products can significantly improve the fading,discoloration or photodegradation of colorants caused by ultraviolet rays.展开更多
In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As...In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.展开更多
A lightweight composite resonator,consisting of a soft material acoustic black hole(SABH)and multiple vibration absorbers,is embedded in a plate to achieve localization and absorption of low-frequency vibration energy...A lightweight composite resonator,consisting of a soft material acoustic black hole(SABH)and multiple vibration absorbers,is embedded in a plate to achieve localization and absorption of low-frequency vibration energy.The combination of local and global admissible functions for displacement enhances the accuracy of the Ritz method in predicting vibration localization characteristics within the SABH domain.Utilizing soft materials for the SABH can reduce the mass and frequency of the composite resonator.Due to the lack of orthogonality between global vibration modes and localized modes,the low-frequency localized modes induced by the SABH are used to shape the initial global modes,thereby concentrating the global vibration of the plate in the SABH region.Consequently,the absorbers of the composite resonator only need to be a small fraction of the mass of the local SABH to achieve substantial vibration control of the host plate.This vibration localization strategy can significantly reduce the vibration amplitude of the host plate and enhance the effectiveness of lightweight absorbers in vibration reduction.展开更多
Sulfur trioxide(SO_(3))as a condensable particle matter has a significant influence on atmospheric visibility,which easily arouses formation of haze.It is imperative to control the SO_(3)emission from the industrial f...Sulfur trioxide(SO_(3))as a condensable particle matter has a significant influence on atmospheric visibility,which easily arouses formation of haze.It is imperative to control the SO_(3)emission from the industrial flue gas.Three commonly used basic absorbents,including Ca(OH)_(2),MgO and NaHCO_(3)were selected to explore the effects of temperature,SO_(2)concentration on the SO_(3)absorption,and the reaction mechanism of SO_(3)absorption was further illustrated.The suitable reaction temperature for various absorbents were proposed,Ca(OH)_(2)at the high temperatures above 500°C,MgO at the low temperatures below 320°C,and NaHCO_(3)at the temperature range of 320–500°C.The competitive absorption between SO_(2)and SO_(3)was found that the addition of SO_(2)reduced the SO_(3)absorption on Ca(OH)_(2)and NaHCO_(3),while had no effect on MgO.The order of the absorption selectivity of SO_(3)follows MgO,NaHCO_(3)and Ca(OH)_(2)under the given conditions in this work.The absorption process of SO_(3)on NaHCO_(3)follows the shrinking core model,thus the absorption reaction continues until NaHCO_(3)was exhausted with the utilization rate of nearly 100%.The absorption process of SO_(3)on Ca(OH)_(2)and MgO follows the grain model,and the dense product layer hinders the further absorption reaction,resulting in low utilization of about 50%for Ca(OH)_(2)and MgO.The research provides a favorable support for the selection of alkaline absorbent for SO_(3)removal in application.展开更多
Broadband and perfect terahertz absorber based on multilayer metamaterial using cross-ring patterned structures is proposed and investigated.The structure of the absorber is double absorption layers consisting of a ch...Broadband and perfect terahertz absorber based on multilayer metamaterial using cross-ring patterned structures is proposed and investigated.The structure of the absorber is double absorption layers consisting of a chromium cross ring and eight isosceles right triangles.The unique structure of the double absorbing layers excites the electric dipole multimode resonance,giving rise to high absorption performance.Meanwhile,the influence of construal parameters on absorber behavior is also discussed.The numerical results show that the absorption achieves over 90%ranging from 2.45 THz to 6.25 THz and 99%absorption in the range of 3.7—5.3 THz.The realization of broadband and perfect absorber is described using the impedance matching principle.It is obviously found that the absorber is insensitive to the high angle of incidence for both transverse electric(TE)and transverse magnetic(TM)polarizations.Compared with the former reports,this absorber has remarkable improved absorption efficiency and smaller period.The terahertz absorber may be found applications in the fields of energy capture and thermal detection.展开更多
The biphasic solvent is a promising solution to reduce regeneration energy consumption in CO_(2) capture.However,most current biphasic solvents suffer from high viscosity and poor desorption of the rich phase.To the i...The biphasic solvent is a promising solution to reduce regeneration energy consumption in CO_(2) capture.However,most current biphasic solvents suffer from high viscosity and poor desorption of the rich phase.To the issues,a novel pentamethyldiethylenetriamine(PMDETA)-2-amino-2-methyl-1-propanol(AMP)/diethylenetriamine(DETA)-sulfolane biphasic solvent was developed.The mechanism of AMP affecting CO_(2) recycling capacity was analyzed.By adjusting the ratio of AMP and DETA,the absorption and desorption performance were balanced,and the recycling capacity and renewable energy consumption of the absorbent were improved.For the P_(2.4)A_(0.8)D_(0.8)S_(2) biphasic solvent,the CO_(2) loading of the rich phase was 5.87 mol/L,and the proportion of the rich phase volume ratio was 35%,which surpasses most reported biphasic solvents.The viscosity of the absorbent significantly decreased from 527.00 mPa·s to 92.26 mPa·s,attributed to the beneficial effect of AMP.Thermodynamic analysis showed that the biphasic solvent produced a lower regeneration energy consumption of 1.70 GJ/t CO_(2),which was 57%lower than that of monoethanolamine(MEA).Overall,the PMDETA-AMP/DETA-sulfolane biphasic solvent exhibited cycle capacity,which provided new insights for the designing of biphasic solvent.展开更多
Transition metal disulfides are widely applied as nonlinear optical materials for laser pulse generation.In this paper,TaS_(2)is successfully used for the first time to achieve a high-energy passively Q-switched erbiu...Transition metal disulfides are widely applied as nonlinear optical materials for laser pulse generation.In this paper,TaS_(2)is successfully used for the first time to achieve a high-energy passively Q-switched erbium-doped fiber(EDF)laser.TaS_(2)nanosheets are prepared by the liquid phase exfoliation method,and then the TaS_(2)solution is mixed with polyvinyl alcohol(PVA).TaS_(2)/PVA film is prepared,which is cut into 1 mm×1 mm flakes.TaS_(2)/PVA saturable absorber(SA)is obtained by sandwiching a small flake between two fiber optic patch cable connectors.With the TaS_(2)/PVA SA added to an EDF laser,a Q-switched fiber laser with a center wavelength of 1560 nm and a repetition rate ranging from 51.33 k Hz to 83.04 k Hz is realized.At the pump power of 231 m W,the maximum output power is 1094μW,and the shortest pulse duration is 3.48μs.The results confirm that the TaS_(2)material has excellent potential for application in nonlinear optics.展开更多
This study aims to investigate the impact of middle ear effusion(MEE)on sound transmission in the human ear and its potential diagnostic significance.Firstly,the material properties of specific structures were adjuste...This study aims to investigate the impact of middle ear effusion(MEE)on sound transmission in the human ear and its potential diagnostic significance.Firstly,the material properties of specific structures were adjusted based on the existing human ear finite element(FE)model,and the accuracy of the model was validated using experimental data.Secondly,six FE models were developed to simulate varying degrees of MEE by systematically altering the material properties of the middle ear cavity(MEC)at different anatomical locations.Finally,the effects of these six FE models,representing varying degrees of MEE,on sound transmission characteristics and energy absorption(EA)rate in the human ear were systematically analyzed.When the degree of MEE is less than 50%of the MEC volume,its impact on the sound transmission characteristics of the human ear remains minimal,resulting in an estimated hearing loss of approximately 3 dB,with EA rate remaining close to normal levels.Once the effusion exceeds 50%of the MEC volume,a significant deterioration in acoustic transmission is observed,accompanied by a flattening of the EA curve and a drop in EA rates to below 20%.When the effusion completely fills the MEC,the maximum hearing loss reaches 46.47 dB,and the EA rate approaches zero across the entire frequency range.These findings provide theoretical insights into the biomechanical effects of MEE on human auditory transmission and offer a reference for clinical diagnosis and evaluation.展开更多
Following publication of the original article[1],the authors found that they pasted the same data when drawing XRD for sample NCO-1 and NCO-2 in Fig.2a,however,the XRD of all four samples in the manuscript was tested,...Following publication of the original article[1],the authors found that they pasted the same data when drawing XRD for sample NCO-1 and NCO-2 in Fig.2a,however,the XRD of all four samples in the manuscript was tested,and XRD raw data were kept and can be offered.The correct Fig.2 has been provided in this Correction.展开更多
In order to meet the growing global energy demand and fulfill energy conservation and emission reduction goals, the efficient utilization of solar energy is becoming increasingly critical. However, the effects of high...In order to meet the growing global energy demand and fulfill energy conservation and emission reduction goals, the efficient utilization of solar energy is becoming increasingly critical. However, the effects of high temperatures on solar absorption are rarely considered in practical research. Therefore, this study presents a porous zinc and silver sulfide solar absorber with high-temperature radiative cooling capabilities. The solar absorption rate and radiative cooling efficiency in the high-temperature range(636 K–1060 K) are computed using the finite-difference time-domain method. Furthermore, the impact of parameters such as characteristic length, porosity, incident angle, and pore shape factor on both the absorption rate and efficiency of the solar absorber is analyzed. The mechanism is further examined from the perspective of microscopic thermal radiation. The results show that, in the high-temperature range, the solar absorption rate increases with higher porosity and incident angles, reaching its peak when the characteristic length is 1 μm. These findings highlight the significant potential of the solar absorber for efficient solar energy harvesting in photo-thermal conversion applications within a specific high-temperature range.展开更多
文摘In today's era of continuous advancement in materials science,the properties of materials are constantly being enhanced,and their application fields are also expanding continuously.SAF(Super Absorbent Fiber),one such material,stands out.Compared to traditional SAP(Super Absorbent Polymer),SAF boasts a unique fibrous form and exceptional performance,presenting broad application prospects.
基金the postdoctoral research grant received from the University of Glasgow for the partial financial support for this research work。
文摘This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered damping amplifier friction vibration absorbers(LDAFVAs)for controlling the structural vibrations and addressing the limitations of conventional tuned mass dampers(TMDs)and frictiontuned mass dampers(FTMDs).The closed-form analytical solution for the optimized design parameters is obtained using the H_(2)and H_(∞)optimization approaches.The efficiency of the recently established closed-form equations for the optimal design parameters is confirmed by the analytical examination.The closed form formulas for the dynamic responses of the main structure and the vibration absorbers are derived using the transfer matrix formulations.The foundation is provided by the harmonic and random-white noise excitations.Moreover,the effectiveness of the innovative dampers has been validated through numerical analysis.The optimal DAFVAs,CDAFVAs,NDAFVAs,and LDAFVAs exhibit at least 30%lower vibration reduction capacity compared with the optimal TMD.To demonstrate the effectiveness of the damping amplification mechanism,the novel absorbers are compared with a conventional FTMD.The results show that the optimized novel absorbers achieve at least 91%greater vibration reduction than the FTMD.These results show how the suggested designs might strengthen the structure's resilience to dynamic loads.
基金supported by the National Key R&D Program of China (Grant Nos. 2023YFC3010703, 2020YFB1708800, and 2023YFC3010705)。
文摘Optically transparent microwave absorbers and multi-band stealth have extensive potential applications in military defense and wireless communication fields, and thus have attracted considerable attention. So far,most related work is based on inorganic transparent conductive metasurfaces. In this paper, we proposed and experimentally demonstrated a flexible, broadband and optically transparent microwave absorber using an organic metasurface. The metasurface absorber is composed of a sandwich structure, in which electric resonances and magnetic resonances are induced resulting in broadband absorption. A spraying process was developed to prepare this metasurface absorber. Both simulations and experiment show that this metasurface has broadband microwave absorption and good optical transparency. We further found that by using a multi-layer structure, visible, radar,and infrared stealth(multi-band stealth) can be achieved simultaneously. With the advantages of excellent foldability and low cost, the proposed metasurfaces may have applications in military and wireless communication fields.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
基金supported by the Natural Science Foundation of Guangdong Province (No.2023A1515010093)the Shenzhen Fundamental Research Program (Nos.JCYJ20220809170611004, JCYJ20231121110828001 and JCYJ20231121113641002)。
文摘Due to their unique physical properties,nonlinear materials are gradually demonstrating significant potential in the field of optics.Gold nanoparticles supported on carbon black(Au/CB),possessing low loss and high nonlinear characteristics,serve as an excellent material for saturable absorber(SA) in ultrafast fiber lasers.In this study,we investigated the performance of Au/CB material and designed an ultrafast fiber laser based on Au/CB SA,successfully observing stable fundamental mode-locking and pulse bunch phenomena.Specifically,when the fiber laser operates in fundamental mode-locking state,the center wavelength of optical spectrum is 1 558.82 nm,with a 3 dB bandwidth of 2.26 nm.Additionally,to investigate the evolution of real-time spectra,the dispersive Fourier transform(DFT) technology is employed.On the other hand,the pulse bunch emitted by the laser is actually composed of numerous random sub-pulses,exhibiting high-energy characteristics.The number of sub-pulses increases with the increase of pump power.These findings contribute to further exploring the properties of Au/CB material and reveal its potential applications in ultrafast optics.
基金supported by the Key Research and Development Projects of Shaanxi Province,China(No.2020 ZDGY01-01)the Fundamental Research Funds for the Central Universities,China(No.D5000220202).
文摘In the field of broadband metamaterial absorbers,most research efforts have focused on optimizing the resonant layers and designing multi-layer structures,but relatively little attention has been paid to the dielectric layers themselves.This paper proposed a method using carbonyl iron powder to modify the dielectric layer.This method significantly enhances the electromagnetic wave attenuation capability of the dielectric layer with the X-band range for metamaterial absorbers.A broadband absorber with a reflection loss(RL)of less than-10 dB within the frequency range of 4.98-18 GHz and covering the C,X,and Ku band was designed.This work analyzed the surface current distribution and the power loss distribution to elucidate the absorption mechanism of the absorber.It was found that the modified dielectric layer accounted for more than 30%of the total loss in the 2-18 GHz frequency band,and the effective absorption bandwidth(RL≤-10 dB)was almost twice that of the unmodified dielectric layer.This enhancement in absorption bandwidth is attributed to the introduction of a new electromagnetic wave loss mechanism by carbonyl iron powder.Meanwhile,the absorber exhibited good angular stability,maintaining at least 80%absorption(RL≤-7 dB)in the 7.0-18.0 GHz range even when the incident angle was increased to 60°.The experimental results showed that the measured results matched the simulation results well.Furthermore,compared with other methods for broadening the absorption bandwidth,the metamaterial absorber obtained by this method offers several advantages,including wideband absorption,thin profile,and a simple manufacturing process.This approach provides a new and promising direction for the design of broadband absorbers.
基金partially funded by the National Natural Science Foundation of China(Grant Nos.52179098 and 41907251)the State Scholarship Fund of China(Grant No.202306650001).
文摘In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in projects susceptible to dynamic shear loads.In laboratory experiments,fully-grouted bolts and energy-absorbing bolts were used as research objects,and artificial rock specimens with rough joints were fabricated to analyze the shear characteristics and damage mechanisms of bolted rock joints under cyclic shear conditions and different shear velocities.The results showed that as the shear rate increased,the shear strength of bolted rock joint specimens decreased.Degradation of asperities resulted in no obvious peak shear stress in the specimens.Energy-absorbing bolts exhibited greater deformation capacity,with significant necking phenomena and the ability to withstand larger shear displacements.In contrast,fully-grouted bolts,which have threaded surfaces that provide higher bonding performance,exhibited a reduced capacity for plastic deformation and were prone to breaking under smaller shear displacements.Although the shear stiffness of specimens reinforced by energy-absorbing bolts was slightly lower than that of fully-grouted bolt specimens,they demonstrated greater stability under various shear rates.The absorbed shear energy showed that energy-absorbing bolts had superior coordinated deformation capabilities,thus exhibiting greater absorbed shear energy than fully-grouted bolts.Overall,fully-grouted bolts are more suitable for projects requiring higher rock shear strength and overall stiffness.In contrast,energy-absorbing bolts are more suitable for coping with dynamic or fluctuating load conditions to maintain the relative stability of jointed rock masses.
基金supported by the National Nat-ural Science Foundation of China(Nos.51872238,52074227,and 21806129)the Fundamental Research Funds for the Central Universities,China(Nos.3102018zy045 and 3102019AX11)+2 种基金the Guangdong Basic and Applied Basic Research Foundation,China(No.2024A1515010298)the Natural Science Basic Research Plan in Shaanxi Province of China(Nos.2017JQ5116 and 2020JM-118)the Key Laboratory of Icing and Anti/De-icing of CARDC(No.IADL20220401).
文摘Gels and conductive polymer composites,including hydrogen bonds(HBs),have emerged as promising materials for electro-magnetic wave(EMW)absorption across various applications.However,the relationship between conduction loss in EMW-absorbing materials and charge transfer in HB remains to be fully understood.In this study,we developed a series of deep eutectic gels to fine-tune the quantity of HB by adjusting the molar ratio of choline chloride(ChCl)and ethylene glycol(EG).Owing to the unique properties of deep eutectic gels,the effects of magnetic loss and polarization loss on EMW attenuation can be disregarded.Our results indicate that the quantity of HB initially increases and then decreases with the introduction of EG,with HB-induced conductive loss following similar pat-terns.At a ChCl and EG molar ratio of 2.4,the gel labeled G22-CE2.4 exhibited the best EMW absorption performance,characterized by an effective absorption bandwidth of 8.50 GHz and a thickness of 2.54 mm.This superior performance is attributed to the synergistic ef-fects of excellent conductive loss and impedance matching generated by the optimal number of HB.This work elucidates the role of HB in dielectric loss for the first time and provides valuable insights into the optimal design of supramolecular polymer absorbers.
基金support of the Key Science Research Project in Colleges and Universities of Anhui Province,China(No.2022AH050813)the Medical Special Cultivation Project of Anhui University of Science and Technology,China(No.YZ2023H2A002).
文摘Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and control-lable preparation of metal oxide/carbon-based composite microwave absorption materials.In this study,a flake-like nickel cobaltate/re-duced graphene oxide/melamine-derived carbon foam(FNC/RGO/MDCF)was successfully fabricated through a combination of solvo-thermal treatment and high-temperature pyrolysis.Results indicated that RGO was evenly distributed in the MDCF skeleton,providing ef-fective support for the load growth of FNC on its surface.Sample S3,the FNC/RGO/MDCF composite prepared by solvothermal method for 16 h,exhibited a minimum reflection loss(RL_(min))of-66.44 dB at a thickness of 2.29 mm.When the thickness was reduced to 1.50 mm,the optimal effective absorption bandwidth was 3.84 GHz.Analysis of the absorption mechanism of FNC/RGO/MDCF revealed that its excellent absorption performance was primarily attributed to the combined effects of conduction loss,multiple reflection,scattering,in-terface polarization,and dipole polarization.
文摘In this paper,a conventional soliton(CS)mode-locked erbium-doped fiber(EDF)laser was de-veloped using MAX phase material(MAX-PM)Nb_(4)AlC_(3)as a saturable absorber(SA).First,the liquid phase exfoliation(LPE)method was utilized to prepare Nb_(4)AlC_(3)nanosheets,and then a piece of tapered fiber was adopted to fabricate Nb_(4)AlC_(3)-SA.It was found that the saturation intensity and modulation depth of the Nb_(4)AlC_(3)-SA are 2.02 MW/cm^(2)and 1.88%.Based on the Nb_(4)AlC_(3)-SA,a conventional soliton(CS)mode-locked EDF laser was achieved.The central wavelength,pulse duration,and pulse repetition rate were found to be 1565.65 nm,615.37 fs,and 24.63 MHz,respectively.The performance is competitive and particularly superior in terms of pulse duration.This study fully confirms that Nb_(4)AlC_(3)possesses marvellous nonlinear saturable absorption properties and opens new possibilities for further research on air-stable ultrafast photon-ic devices.
文摘Color plays an important role in the daily chemical product market,and transparent packaging of daily chemical products are loved by consumers,but it is difficult to avoid fading,discoloration or photodegradation of the inner material of the product.UV light is a major contributor to colorant fading,which can affect color stability by damaging chromogenic groups and producing free radicals.In view of this,the combination of four ultraviolet absorbers DHHB,OS,OMC,and MCE was investigated,and the photostability of five common colorants in cosmetics was studied.After 28 days of photostability test,the pigment preservation rate was analyzed,and the results showed that 0.1%of the UV absorber compound could have a certain protective effect on the colorant,and 0.5%of the compound could significantly improve the photostability of the colorant.Adding ultraviolet absorbers to daily chemical products can significantly improve the fading,discoloration or photodegradation of colorants caused by ultraviolet rays.
基金Project supported by the National Natural Science Foundation of China(Grant No.12164030)Young Science and Technology Talents of Inner Mongolia,China(Grant No.NJYT22101)+1 种基金the Central Government Guides Local Science,the Technology Development Fund Projects(Grant No.2023ZY0005)the Science and Technology Plan Projects of Inner Mongolia Autonomous Region of China(Grant No.2023KYPT0012)。
文摘In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.
基金supported by the National Natural Science Foundation of China(Grant Nos.12302006,12132002,and 62188101).
文摘A lightweight composite resonator,consisting of a soft material acoustic black hole(SABH)and multiple vibration absorbers,is embedded in a plate to achieve localization and absorption of low-frequency vibration energy.The combination of local and global admissible functions for displacement enhances the accuracy of the Ritz method in predicting vibration localization characteristics within the SABH domain.Utilizing soft materials for the SABH can reduce the mass and frequency of the composite resonator.Due to the lack of orthogonality between global vibration modes and localized modes,the low-frequency localized modes induced by the SABH are used to shape the initial global modes,thereby concentrating the global vibration of the plate in the SABH region.Consequently,the absorbers of the composite resonator only need to be a small fraction of the mass of the local SABH to achieve substantial vibration control of the host plate.This vibration localization strategy can significantly reduce the vibration amplitude of the host plate and enhance the effectiveness of lightweight absorbers in vibration reduction.
基金supported by the National Natural Science Foundation of China(No.52000172)the National Key R&D Program of China(Nos.2017YFB0304300 and 2017YFB0304303).
文摘Sulfur trioxide(SO_(3))as a condensable particle matter has a significant influence on atmospheric visibility,which easily arouses formation of haze.It is imperative to control the SO_(3)emission from the industrial flue gas.Three commonly used basic absorbents,including Ca(OH)_(2),MgO and NaHCO_(3)were selected to explore the effects of temperature,SO_(2)concentration on the SO_(3)absorption,and the reaction mechanism of SO_(3)absorption was further illustrated.The suitable reaction temperature for various absorbents were proposed,Ca(OH)_(2)at the high temperatures above 500°C,MgO at the low temperatures below 320°C,and NaHCO_(3)at the temperature range of 320–500°C.The competitive absorption between SO_(2)and SO_(3)was found that the addition of SO_(2)reduced the SO_(3)absorption on Ca(OH)_(2)and NaHCO_(3),while had no effect on MgO.The order of the absorption selectivity of SO_(3)follows MgO,NaHCO_(3)and Ca(OH)_(2)under the given conditions in this work.The absorption process of SO_(3)on NaHCO_(3)follows the shrinking core model,thus the absorption reaction continues until NaHCO_(3)was exhausted with the utilization rate of nearly 100%.The absorption process of SO_(3)on Ca(OH)_(2)and MgO follows the grain model,and the dense product layer hinders the further absorption reaction,resulting in low utilization of about 50%for Ca(OH)_(2)and MgO.The research provides a favorable support for the selection of alkaline absorbent for SO_(3)removal in application.
基金supported by the National Natural Science Foundation of China(No.61505160)the Innovation Capability Support Program of Shaanxi(No.2018KJXX-042)+1 种基金the Natural Science Basic Research Program of Shaanxi(No.2019JM-084)the State Key Laboratory of Transient Optics and Photonics(No.SKLST202108)。
文摘Broadband and perfect terahertz absorber based on multilayer metamaterial using cross-ring patterned structures is proposed and investigated.The structure of the absorber is double absorption layers consisting of a chromium cross ring and eight isosceles right triangles.The unique structure of the double absorbing layers excites the electric dipole multimode resonance,giving rise to high absorption performance.Meanwhile,the influence of construal parameters on absorber behavior is also discussed.The numerical results show that the absorption achieves over 90%ranging from 2.45 THz to 6.25 THz and 99%absorption in the range of 3.7—5.3 THz.The realization of broadband and perfect absorber is described using the impedance matching principle.It is obviously found that the absorber is insensitive to the high angle of incidence for both transverse electric(TE)and transverse magnetic(TM)polarizations.Compared with the former reports,this absorber has remarkable improved absorption efficiency and smaller period.The terahertz absorber may be found applications in the fields of energy capture and thermal detection.
基金supported by the Key R&D Program of Yunnan Province(No.202303AC100008)the National Natural Science Foundation of China(No.52100133)the Major Science and Technology-Special Plan“Unveiling and Leading”Project of Shanxi Province(No.202201050201011).
文摘The biphasic solvent is a promising solution to reduce regeneration energy consumption in CO_(2) capture.However,most current biphasic solvents suffer from high viscosity and poor desorption of the rich phase.To the issues,a novel pentamethyldiethylenetriamine(PMDETA)-2-amino-2-methyl-1-propanol(AMP)/diethylenetriamine(DETA)-sulfolane biphasic solvent was developed.The mechanism of AMP affecting CO_(2) recycling capacity was analyzed.By adjusting the ratio of AMP and DETA,the absorption and desorption performance were balanced,and the recycling capacity and renewable energy consumption of the absorbent were improved.For the P_(2.4)A_(0.8)D_(0.8)S_(2) biphasic solvent,the CO_(2) loading of the rich phase was 5.87 mol/L,and the proportion of the rich phase volume ratio was 35%,which surpasses most reported biphasic solvents.The viscosity of the absorbent significantly decreased from 527.00 mPa·s to 92.26 mPa·s,attributed to the beneficial effect of AMP.Thermodynamic analysis showed that the biphasic solvent produced a lower regeneration energy consumption of 1.70 GJ/t CO_(2),which was 57%lower than that of monoethanolamine(MEA).Overall,the PMDETA-AMP/DETA-sulfolane biphasic solvent exhibited cycle capacity,which provided new insights for the designing of biphasic solvent.
基金Project supported by the National Natural Science Foundation of China(Grant No.12075190)the Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant No.23JSY019)。
文摘Transition metal disulfides are widely applied as nonlinear optical materials for laser pulse generation.In this paper,TaS_(2)is successfully used for the first time to achieve a high-energy passively Q-switched erbium-doped fiber(EDF)laser.TaS_(2)nanosheets are prepared by the liquid phase exfoliation method,and then the TaS_(2)solution is mixed with polyvinyl alcohol(PVA).TaS_(2)/PVA film is prepared,which is cut into 1 mm×1 mm flakes.TaS_(2)/PVA saturable absorber(SA)is obtained by sandwiching a small flake between two fiber optic patch cable connectors.With the TaS_(2)/PVA SA added to an EDF laser,a Q-switched fiber laser with a center wavelength of 1560 nm and a repetition rate ranging from 51.33 k Hz to 83.04 k Hz is realized.At the pump power of 231 m W,the maximum output power is 1094μW,and the shortest pulse duration is 3.48μs.The results confirm that the TaS_(2)material has excellent potential for application in nonlinear optics.
基金supported by the National Natural Science Foundation of China(52275296)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘This study aims to investigate the impact of middle ear effusion(MEE)on sound transmission in the human ear and its potential diagnostic significance.Firstly,the material properties of specific structures were adjusted based on the existing human ear finite element(FE)model,and the accuracy of the model was validated using experimental data.Secondly,six FE models were developed to simulate varying degrees of MEE by systematically altering the material properties of the middle ear cavity(MEC)at different anatomical locations.Finally,the effects of these six FE models,representing varying degrees of MEE,on sound transmission characteristics and energy absorption(EA)rate in the human ear were systematically analyzed.When the degree of MEE is less than 50%of the MEC volume,its impact on the sound transmission characteristics of the human ear remains minimal,resulting in an estimated hearing loss of approximately 3 dB,with EA rate remaining close to normal levels.Once the effusion exceeds 50%of the MEC volume,a significant deterioration in acoustic transmission is observed,accompanied by a flattening of the EA curve and a drop in EA rates to below 20%.When the effusion completely fills the MEC,the maximum hearing loss reaches 46.47 dB,and the EA rate approaches zero across the entire frequency range.These findings provide theoretical insights into the biomechanical effects of MEE on human auditory transmission and offer a reference for clinical diagnosis and evaluation.
文摘Following publication of the original article[1],the authors found that they pasted the same data when drawing XRD for sample NCO-1 and NCO-2 in Fig.2a,however,the XRD of all four samples in the manuscript was tested,and XRD raw data were kept and can be offered.The correct Fig.2 has been provided in this Correction.
基金Project supported by the National Natural Science Foundation of China (Grant No. 52406102)Shandong Provincial Natural Science Foundation (Grant No. ZR2023QE258)。
文摘In order to meet the growing global energy demand and fulfill energy conservation and emission reduction goals, the efficient utilization of solar energy is becoming increasingly critical. However, the effects of high temperatures on solar absorption are rarely considered in practical research. Therefore, this study presents a porous zinc and silver sulfide solar absorber with high-temperature radiative cooling capabilities. The solar absorption rate and radiative cooling efficiency in the high-temperature range(636 K–1060 K) are computed using the finite-difference time-domain method. Furthermore, the impact of parameters such as characteristic length, porosity, incident angle, and pore shape factor on both the absorption rate and efficiency of the solar absorber is analyzed. The mechanism is further examined from the perspective of microscopic thermal radiation. The results show that, in the high-temperature range, the solar absorption rate increases with higher porosity and incident angles, reaching its peak when the characteristic length is 1 μm. These findings highlight the significant potential of the solar absorber for efficient solar energy harvesting in photo-thermal conversion applications within a specific high-temperature range.
