In view of low recognition rate of complex radar intra-pulse modulation signal type by traditional methods under low signal-to-noise ratio(SNR),the paper proposes an automatic recog-nition method of complex radar intr...In view of low recognition rate of complex radar intra-pulse modulation signal type by traditional methods under low signal-to-noise ratio(SNR),the paper proposes an automatic recog-nition method of complex radar intra-pulse modulation signal type based on deep residual network.The basic principle of the recognition method is to obtain the transformation relationship between the time and frequency of complex radar intra-pulse modulation signal through short-time Fourier transform(STFT),and then design an appropriate deep residual network to extract the features of the time-frequency map and complete a variety of complex intra-pulse modulation signal type recognition.In addition,in order to improve the generalization ability of the proposed method,label smoothing and L2 regularization are introduced.The simulation results show that the proposed method has a recognition accuracy of more than 95%for complex radar intra-pulse modulation sig-nal types under low SNR(2 dB).展开更多
The caries-preventive effects of arginine have been attributed to its impact on biofilm composition and pH.Recent in vitro studies suggest that arginine also affects the production of biofilm matrix components that co...The caries-preventive effects of arginine have been attributed to its impact on biofilm composition and pH.Recent in vitro studies suggest that arginine also affects the production of biofilm matrix components that contribute to virulence,but this mechanism has not been investigated clinically.This randomized,placebo-controlled,triple-blind,split-mouth in situ trial assessed arginine's impact on the microbial composition,matrix architecture,and microscale pH of biofilms from caries-active patients(N=10).We also examined whether individual differences in the pH response to arginine were related to biofilm composition and matrix structure.Biofilms were grown for four days on carriers attached to intraoral splints.Three times daily,the biofilms were treated extraorally with sucrose(5 min),followed by arginine or placebo(30 min),in a split-mouth design.After growth,the microscale biofilm p H response to sucrose was monitored by pH ratiometry.Microbial biofilm composition and carbohydrate matrix architecture were analyzed by 16S rRNA gene sequencing and fluorescence lectin-binding analysis,respectively.Arginine treatment significantly mitigated sucrose-induced pH drops,reduced total carbohydrate matrix production,and altered the spatial distribution of fucoseand galactose-containing carbohydrates.Both arginine-and placebo-treated biofilms were dominated by streptococci and Veillonella spp.Paired analyses showed a significant reduction in mitis/oralis group streptococci and a non-significant increase in several arginine metabolizers in arginine-treated biofilms.Individual pH responses were not significantly associated with the abundance of specific bacterial taxa or carbohydrate matrix components.In conclusion,arginine reduced the virulence of biofilms from caries-active patients through multiple mechanisms,including suppressing matrix carbohydrate production.展开更多
With the continuous improvement of China's science and technology, the design method of steel structure is also more and more, how to better apply the module building design method to the related buildings, is the...With the continuous improvement of China's science and technology, the design method of steel structure is also more and more, how to better apply the module building design method to the related buildings, is the current issue to focus on consideration. Therefore, this paper will focus on the design method of multi-layer steel structure module and steel frame composite building structure, and analyze and study its structure, so as to improve the utilization rate of steel structure and promote the development of the construction industry.展开更多
This study uses NCEP/NCAR daily reanalysis data,NOAA outgoing long-wave radiation(OLR) data,the real-time multivariate MJO(RMM) index from the Australian Bureau of Meteorology and Tibetan Plateau vortex(TPV)data from ...This study uses NCEP/NCAR daily reanalysis data,NOAA outgoing long-wave radiation(OLR) data,the real-time multivariate MJO(RMM) index from the Australian Bureau of Meteorology and Tibetan Plateau vortex(TPV)data from the Chengdu Institute of Plateau Meteorology to discuss modulation of the Madden-Julian Oscillation(MJO)on the Tibetan Plateau Vortex(TPV).Wavelet and composite analysis are used.Results show that the MJO plays an important role in the occurrence of the TPV that the number of TPVs generated within an active period of the MJO is three times as much as that during an inactive period.In addition,during the active period,the number of the TPVs generated in phases 1 and 2 is larger than that in phases 3 and 7.After compositing phases 1 and 7 separately,all meteorological elements in phase 1 are apparently conducive to the generation of the TPV,whereas those in phase 7 are somewhat constrained.With its eastward propagation process,the MJO convection centre spreads eastward,and the vertical circulation within the tropical atmosphere changes.Due to the interaction between the mid-latitude and low-latitude atmosphere,changes occur in the baroclinic characteristics of the atmosphere,the available potential energy and eddy available potential energy of the atmosphere,and the circulation structures of the atmosphere over the Tibetan Plateau(TP) and surrounding areas.This results in significantly different water vapour transportation and latent heat distribution.Advantageous and disadvantageous conditions therefore alternate,leading to a significant difference among the numbers of plateau vortex in different phases.展开更多
A composition-modulated （HfO2）x（Al2O3）1-x charge trapping layer is proposed for charge trap flash memory by controlling the A1 atom content to form a peak and valley shaped band gap. It is found that the memory de...A composition-modulated （HfO2）x（Al2O3）1-x charge trapping layer is proposed for charge trap flash memory by controlling the A1 atom content to form a peak and valley shaped band gap. It is found that the memory device using the composition-modulated （HfO2）x（Al2O3）l-x as the charge trapping layer exhibits a larger memory window of 11.5 V, improves data retention even at high temperature, and enhances the program/erase speed. Improvements of the memory characteristics are attributed to the special band-gap structure resulting from the composition-modulated trapping layer. Therefore, the composition-modulated charge trapping layer may be useful in future nonvolatile flash memory device application.展开更多
Broadband absorbers based on resonant acoustic metamaterials often require intricate designs,yet this complexity inherently restricts their bandwidth,robustness,and manufacturability.To overcome these constraints,we p...Broadband absorbers based on resonant acoustic metamaterials often require intricate designs,yet this complexity inherently restricts their bandwidth,robustness,and manufacturability.To overcome these constraints,we present a composite sound-absorbing metamaterial that combines multiple resonance coupling with quality factor modulation,leveraging micro-perforated plates and porous materials.This metamaterial exhibits near-perfect broadband sound absorption across a frequency range spanning from 340 to 3200Hz.In addition,composite metamaterials exhibit greater robustness compared to resonant metamaterials,demonstrating better noise control capabilities in diffuse sound fields.This work uses a new mechanism to revitalize traditional sound-absorbing materials and bring them back to prominence in noise control.We anticipate that this innovative solution will address noise control challenges in demanding environments and provide a reference for further development of soundabsorbing metamaterials.展开更多
TiO-2/SiO-2 mesoporous composite was synthesized by soaking_hydrolyzing method and its structure was characterized. The relationship between the shift of absorption edge and the amount of TiO-2 nanoparticles within th...TiO-2/SiO-2 mesoporous composite was synthesized by soaking_hydrolyzing method and its structure was characterized. The relationship between the shift of absorption edge and the amount of TiO-2 nanoparticles within the mesopores of SiO-2 as well as the annealing temperature was investigated. The results indicate that the extent of the blue shift of absorption edge increases with the decreasing amount of nanoparticles and decreases wtih the increasing annealing temperature.展开更多
Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering impleme...Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering implementation,for instance in aerospace structural components.This work achieved a transfor-mative improvement of room-temperature tensile ductility in Ti-V-Zr-Nb MEAs with densities of 5.4-6.5 g/cm3,via ingenious composition modulation.Through the systematic co-adjustment of Ti and V contents,an intrinsic ductility mechanism was unveiled,manifested by a transition from predominant intergranular brittle fracture to pervasive ductile dimpled rupture.Notably,the modulated deformation mechanisms evolved from solitary slip toward collaborative multiple slip modes,without significantly compromising strength.Compared to equimolar Ti-V-Zr-Nb,a(Ti1.5V)3ZrNb composition demonstrated an impressive 360%improvement in elongation while sustaining a high yield strength of around 800 MPa.Increasing Ti and V not only purified the grain boundaries by reducing detrimental phases,but also tai-lored the deformation dislocation configurations.These insights expanded the applicability of lightweight HEAs to areas demanding combined high strength and ductility.展开更多
A melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties.Sintered at 960℃,the Ba2CuGe2O7 ceramic had a high relative density 97%,a low relative permitt...A melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties.Sintered at 960℃,the Ba2CuGe2O7 ceramic had a high relative density 97%,a low relative permittivity(εr)9.43,a quality factor(Q×f)of 20,000 GHz,and a temperature coefficient of resonance frequency(τf)-76 ppm/℃.To get a deep understanding of the relationship between composition,structure,and dielectric performances,magnesium substitution for copper in Ba2CuGe2O7 was conducted.Influences of magnesium doping on the sintering behavior,crystal structure,and microwave dielectric properties were studied.Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure,grain morphology,and size distribution,while induced visible variation in the local structure as revealed by Raman analysis.Microwave dielectric properties exhibit a remarkable dependence on composition.On increasing the magnesium content,the relative permittivity featured a continuous decrease,while both the quality factor and the temperature coefficient of resonance frequency increased monotonously.Such variations in dielectric performances were clarified in terms of the polarizability,packing fraction,and band valence theory.展开更多
ZrCoSb based half-Heusler(HH)alloys have been widely studied as a p-type thermoelectric(TE)material for power generation applications in the mid-temperature regime.However,their intrinsically high thermal conductivity...ZrCoSb based half-Heusler(HH)alloys have been widely studied as a p-type thermoelectric(TE)material for power generation applications in the mid-temperature regime.However,their intrinsically high thermal conductivity has been found to be detrimental for the improvement in their thermoelectric figure-of-merit(ZT),which presently is far below unity.In the current work,a state-of-the-art ZT~1.1 at 873 K was realized in an optimized composition of nanostructured Zr1-xHfxCoSb_(0.9)Sn_(0.1) HH alloys by employing compositional modulation i.e.grain-by-grain compositional variations,which leads to a substantial increase in its power factor coupled with a concurrent decrease in its thermal conductivity.Significant reduction in the phonon mean-free-path is observed on Hf substitution,which is comparable to the average crystallite size(~25 nm),thus leading to a very low thermal conductivity of~2.2Wm^(-1)K^(-1) at 873 K,which is amongst the lowest reported in HH alloys.The TE device characteristics,estimated using cumulative temperature dependence model for quantitative evaluation of TE performance,yielded an output power density of~10 Wcm2 with a leg efficiency of~10%in the optimized composition of nanostructured Zr_(1-x)Hf_(x)CoSb_(0.9)Sn_(0.1) HH alloys,which is comparable to the reported efficiencies of other state-of-the-art TE materials.展开更多
文摘In view of low recognition rate of complex radar intra-pulse modulation signal type by traditional methods under low signal-to-noise ratio(SNR),the paper proposes an automatic recog-nition method of complex radar intra-pulse modulation signal type based on deep residual network.The basic principle of the recognition method is to obtain the transformation relationship between the time and frequency of complex radar intra-pulse modulation signal through short-time Fourier transform(STFT),and then design an appropriate deep residual network to extract the features of the time-frequency map and complete a variety of complex intra-pulse modulation signal type recognition.In addition,in order to improve the generalization ability of the proposed method,label smoothing and L2 regularization are introduced.The simulation results show that the proposed method has a recognition accuracy of more than 95%for complex radar intra-pulse modulation sig-nal types under low SNR(2 dB).
基金supported by the Faculty of Health,Aarhus University,Denmark。
文摘The caries-preventive effects of arginine have been attributed to its impact on biofilm composition and pH.Recent in vitro studies suggest that arginine also affects the production of biofilm matrix components that contribute to virulence,but this mechanism has not been investigated clinically.This randomized,placebo-controlled,triple-blind,split-mouth in situ trial assessed arginine's impact on the microbial composition,matrix architecture,and microscale pH of biofilms from caries-active patients(N=10).We also examined whether individual differences in the pH response to arginine were related to biofilm composition and matrix structure.Biofilms were grown for four days on carriers attached to intraoral splints.Three times daily,the biofilms were treated extraorally with sucrose(5 min),followed by arginine or placebo(30 min),in a split-mouth design.After growth,the microscale biofilm p H response to sucrose was monitored by pH ratiometry.Microbial biofilm composition and carbohydrate matrix architecture were analyzed by 16S rRNA gene sequencing and fluorescence lectin-binding analysis,respectively.Arginine treatment significantly mitigated sucrose-induced pH drops,reduced total carbohydrate matrix production,and altered the spatial distribution of fucoseand galactose-containing carbohydrates.Both arginine-and placebo-treated biofilms were dominated by streptococci and Veillonella spp.Paired analyses showed a significant reduction in mitis/oralis group streptococci and a non-significant increase in several arginine metabolizers in arginine-treated biofilms.Individual pH responses were not significantly associated with the abundance of specific bacterial taxa or carbohydrate matrix components.In conclusion,arginine reduced the virulence of biofilms from caries-active patients through multiple mechanisms,including suppressing matrix carbohydrate production.
文摘With the continuous improvement of China's science and technology, the design method of steel structure is also more and more, how to better apply the module building design method to the related buildings, is the current issue to focus on consideration. Therefore, this paper will focus on the design method of multi-layer steel structure module and steel frame composite building structure, and analyze and study its structure, so as to improve the utilization rate of steel structure and promote the development of the construction industry.
基金National Basic Research Program of China(2012CB417202)National Natural Science Foundation of China(41175045,91337215,Ul 133603)Special Fund for Meteorological Research in the Public Interest(GYHY201206042)
文摘This study uses NCEP/NCAR daily reanalysis data,NOAA outgoing long-wave radiation(OLR) data,the real-time multivariate MJO(RMM) index from the Australian Bureau of Meteorology and Tibetan Plateau vortex(TPV)data from the Chengdu Institute of Plateau Meteorology to discuss modulation of the Madden-Julian Oscillation(MJO)on the Tibetan Plateau Vortex(TPV).Wavelet and composite analysis are used.Results show that the MJO plays an important role in the occurrence of the TPV that the number of TPVs generated within an active period of the MJO is three times as much as that during an inactive period.In addition,during the active period,the number of the TPVs generated in phases 1 and 2 is larger than that in phases 3 and 7.After compositing phases 1 and 7 separately,all meteorological elements in phase 1 are apparently conducive to the generation of the TPV,whereas those in phase 7 are somewhat constrained.With its eastward propagation process,the MJO convection centre spreads eastward,and the vertical circulation within the tropical atmosphere changes.Due to the interaction between the mid-latitude and low-latitude atmosphere,changes occur in the baroclinic characteristics of the atmosphere,the available potential energy and eddy available potential energy of the atmosphere,and the circulation structures of the atmosphere over the Tibetan Plateau(TP) and surrounding areas.This results in significantly different water vapour transportation and latent heat distribution.Advantageous and disadvantageous conditions therefore alternate,leading to a significant difference among the numbers of plateau vortex in different phases.
基金supported by the Science and Technology Research Key Project of Education Department of Henan, China (Grant No. 13A140021)the National Natural Science Foundation of China (Grant Nos. 50972054 and 61176124)+1 种基金the National Basic Research Program of China (Grant No. 2010CB934201)the State Key Program for Science and Technology of China (Grant No. 2009ZX02039-004)
文摘A composition-modulated （HfO2）x（Al2O3）1-x charge trapping layer is proposed for charge trap flash memory by controlling the A1 atom content to form a peak and valley shaped band gap. It is found that the memory device using the composition-modulated （HfO2）x（Al2O3）l-x as the charge trapping layer exhibits a larger memory window of 11.5 V, improves data retention even at high temperature, and enhances the program/erase speed. Improvements of the memory characteristics are attributed to the special band-gap structure resulting from the composition-modulated trapping layer. Therefore, the composition-modulated charge trapping layer may be useful in future nonvolatile flash memory device application.
基金supported by the Local Science and Technology Development Fund Project(Grant No.YDZX20233100004002)the Shanghai 3-year Action Plan(No.GWVI11.1-37)+1 种基金the Shanghai Pilot Program for Basic Research,the National Natural Science Foundation of China(NSFC)(Grant Nos.12404508,12404509,and 124B2087)the Xiaomi Young Talents Program.
文摘Broadband absorbers based on resonant acoustic metamaterials often require intricate designs,yet this complexity inherently restricts their bandwidth,robustness,and manufacturability.To overcome these constraints,we present a composite sound-absorbing metamaterial that combines multiple resonance coupling with quality factor modulation,leveraging micro-perforated plates and porous materials.This metamaterial exhibits near-perfect broadband sound absorption across a frequency range spanning from 340 to 3200Hz.In addition,composite metamaterials exhibit greater robustness compared to resonant metamaterials,demonstrating better noise control capabilities in diffuse sound fields.This work uses a new mechanism to revitalize traditional sound-absorbing materials and bring them back to prominence in noise control.We anticipate that this innovative solution will address noise control challenges in demanding environments and provide a reference for further development of soundabsorbing metamaterials.
文摘TiO-2/SiO-2 mesoporous composite was synthesized by soaking_hydrolyzing method and its structure was characterized. The relationship between the shift of absorption edge and the amount of TiO-2 nanoparticles within the mesopores of SiO-2 as well as the annealing temperature was investigated. The results indicate that the extent of the blue shift of absorption edge increases with the decreasing amount of nanoparticles and decreases wtih the increasing annealing temperature.
基金supported by the National Natural Science Foundation of China(Nos.51925103,52271149,52171159)the Innovation Program of Shanghai Municipal Education Commission(No.2021-01-07-00-09-E00114)+5 种基金the Natural Science Foundation of Shanghai(22ZR1422500)the Innovation Program of Shanghai Science and Technology(No.23520760700)the Aviation Foundation(No.2023Z0530S6004)the Fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP202221)the financial support from Program 173(No.2020-JCIQ-ZD-186-01)the Space Utilization System of China Manned Space Engineering(No.KJZ-YY-NCL08).
文摘Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering implementation,for instance in aerospace structural components.This work achieved a transfor-mative improvement of room-temperature tensile ductility in Ti-V-Zr-Nb MEAs with densities of 5.4-6.5 g/cm3,via ingenious composition modulation.Through the systematic co-adjustment of Ti and V contents,an intrinsic ductility mechanism was unveiled,manifested by a transition from predominant intergranular brittle fracture to pervasive ductile dimpled rupture.Notably,the modulated deformation mechanisms evolved from solitary slip toward collaborative multiple slip modes,without significantly compromising strength.Compared to equimolar Ti-V-Zr-Nb,a(Ti1.5V)3ZrNb composition demonstrated an impressive 360%improvement in elongation while sustaining a high yield strength of around 800 MPa.Increasing Ti and V not only purified the grain boundaries by reducing detrimental phases,but also tai-lored the deformation dislocation configurations.These insights expanded the applicability of lightweight HEAs to areas demanding combined high strength and ductility.
基金National Natural Science Foundation of China(No.62061011)National Key R&D Program of China(No.2017YFB0406300)+1 种基金Natural Science Foundation of Guangxi Zhuang Autonomous Region(No.2018GXNSFAA281253)high-level innovation team and outstanding scholar program of Guangxi institutes.
文摘A melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties.Sintered at 960℃,the Ba2CuGe2O7 ceramic had a high relative density 97%,a low relative permittivity(εr)9.43,a quality factor(Q×f)of 20,000 GHz,and a temperature coefficient of resonance frequency(τf)-76 ppm/℃.To get a deep understanding of the relationship between composition,structure,and dielectric performances,magnesium substitution for copper in Ba2CuGe2O7 was conducted.Influences of magnesium doping on the sintering behavior,crystal structure,and microwave dielectric properties were studied.Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure,grain morphology,and size distribution,while induced visible variation in the local structure as revealed by Raman analysis.Microwave dielectric properties exhibit a remarkable dependence on composition.On increasing the magnesium content,the relative permittivity featured a continuous decrease,while both the quality factor and the temperature coefficient of resonance frequency increased monotonously.Such variations in dielectric performances were clarified in terms of the polarizability,packing fraction,and band valence theory.
基金the Board of Research in Nuclear Sciences,India for the financial support under the Scheme:37(3)/14/22/2016-BRNS with BSC.Nagendra S.Chauhan acknowledges CSIR-Senior Research Fellowship.(Grant No:31/001(0430)/2014-EMR-1)The technical support rendered by Dr.Vidya Nand Singh,Mr.Radhey Shyam,and Mr.Naval Kishor Upadhyay is also gratefully acknowledged.
文摘ZrCoSb based half-Heusler(HH)alloys have been widely studied as a p-type thermoelectric(TE)material for power generation applications in the mid-temperature regime.However,their intrinsically high thermal conductivity has been found to be detrimental for the improvement in their thermoelectric figure-of-merit(ZT),which presently is far below unity.In the current work,a state-of-the-art ZT~1.1 at 873 K was realized in an optimized composition of nanostructured Zr1-xHfxCoSb_(0.9)Sn_(0.1) HH alloys by employing compositional modulation i.e.grain-by-grain compositional variations,which leads to a substantial increase in its power factor coupled with a concurrent decrease in its thermal conductivity.Significant reduction in the phonon mean-free-path is observed on Hf substitution,which is comparable to the average crystallite size(~25 nm),thus leading to a very low thermal conductivity of~2.2Wm^(-1)K^(-1) at 873 K,which is amongst the lowest reported in HH alloys.The TE device characteristics,estimated using cumulative temperature dependence model for quantitative evaluation of TE performance,yielded an output power density of~10 Wcm2 with a leg efficiency of~10%in the optimized composition of nanostructured Zr_(1-x)Hf_(x)CoSb_(0.9)Sn_(0.1) HH alloys,which is comparable to the reported efficiencies of other state-of-the-art TE materials.
