Soil compaction often imposes stress on root development and plant survival.However,root anatomical responses that enable persistent root growth and functioning under soil compaction remain unclear.We grew 10 herbaceo...Soil compaction often imposes stress on root development and plant survival.However,root anatomical responses that enable persistent root growth and functioning under soil compaction remain unclear.We grew 10 herbaceous species differing substantially in lateral root diameter,in soils with low(1.0 g cm^(-3))and high(1.4 g cm^(-3))bulk density,and assessed root traits including root biomass,anatomical structures,and respiration rates.Greater root thickening upon soil compaction was found in species with thicker first-order lateral roots,mainly due to larger cortical cell size.Both xylem vessel diameter and wall thickness increased more in compacted soils in these species.Despite these anatomical shifts,root respiration rate responded little to soil compaction across most species,likely due to the opposite investment in cortical cells and xylem vessels.Notably,root biomass,independent of root respiration rate and anatomical structures,determined whole-plant growth under soil compaction.Our study reveals two independent strategies of root response to soil compaction:anatomical remodeling for mechanical and metabolic maintenance,and root biomass investment for resource acquisition.These findings offer new insights for breeding and selecting species tolerant to soil compaction and highlight multidimensional strategies of plant adaptation to physical stress.展开更多
Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain anal...Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.展开更多
Laser-assisted drilling combined with full-size polycrystalline diamond compact(PDC)bit is considered a feasible solution to enhance the drilling performance of engineering machinery.In this method,determining the opt...Laser-assisted drilling combined with full-size polycrystalline diamond compact(PDC)bit is considered a feasible solution to enhance the drilling performance of engineering machinery.In this method,determining the optimal collaborative control parameters that support rapid drilling is crucial for improving the combined performance.This study used average drilling speed,average torque,and total specificenergy for quantitative analysis to characterize the efficiencyand economy of combined rock breaking.Given the advantage of the response surface methodology in providing high-precision predictions with limited experimental data,regression models of the average drilling speed,average torque,and total specificenergy were established.The results showed that as the laser power and irradiation time increased,the average drilling speed firstincreased rapidly and then leveled off,while the average torque decreased sharply before decelerating.The total specificenergy initially decreased and then increased,with the combined drilling outperforming conventional mechanical drilling within specific parameter ranges.As the weight on bit increased,both the average torque and total specificenergy first decreased and then increased.With rising rotating speed,the average torque exhibited a trend of initial increase,then decrease,and finalincrease,whereas the total specificenergy increased slowly at firstand then sharply.Both parameters exhibited optimal values at which the average torque and total specific energy remained at minimal levels.For granite combined drilling,the optimal performance was achieved at a laser power of 3000 W,irradiation time of 31 s,the weight on bit of 2.4 kN,and the rotating speed of 97 r/min.展开更多
Coating uniform,compact and thin nanoshells on micro-sized particles is critical to various applications including anticorrosive broadband microwave absorbing materials(MAMs),yet effective processing methods remain la...Coating uniform,compact and thin nanoshells on micro-sized particles is critical to various applications including anticorrosive broadband microwave absorbing materials(MAMs),yet effective processing methods remain lacking.In this work,a turbulent sol-gel method is developed to coat the desired SiO2 nanoshells on flaky carbonyl iron(FCI)particles.The adding millimeter-sized zirconia balls,driven by the orbital shaking,squeeze the solution and create significant relative motion between the liquid and balls,which generates turbulent flows.This significantly promotes the heterogeneous nucleation rate and high nucleation density,ultimately forming highly compact and uniform SiO2 nanoshells covering FCI particles to enhance the electromagnetic absorption and anticorrosion properties.The as-obtained core-shell particles minimize the interface polarization and retain high magnetic loss,resulting in an improved impedance matching and a reflection loss<−10 dB with a bandwidth of 6.5 GHz at a thin thickness of 1 mm.Moreover,they also show a substantial order-of-magnitude improvement in anticorrosion performance.This work provides a promising method to fabricate anticorrosive,broadband and thin-thickness MAMs.The turbulent sol-gel method developed herein offers a facile and effective approach for fabricating uniform compact nanoshells on micro-sized particles.展开更多
The models constructed by particle flow simulation method can effectively simulate the heterogeneous substance characteristics and failure behaviors of rocks.However,existing contact models overlook the rock cracks,an...The models constructed by particle flow simulation method can effectively simulate the heterogeneous substance characteristics and failure behaviors of rocks.However,existing contact models overlook the rock cracks,and the various simulation methods that do consider cracks still exhibit certain limitations.In this paper,based on Flat-Joint model and Linear Parallel Bond model,a crack contact model considering linked substance in the crack is proposed by splitting the crack contact into two portions:linked portion and unlinked portion for calculation.The new contact model considers the influence of crack closure on the contact force-displacement law.And a better compressive tensile strength ratio(UCS/T)was obtained by limiting the failure of the contact bond to be solely controlled by the contact force and moment of the linked portion.Then,by employing the FISH Model tool within the Particle Flow Code,the contact model was constructed and verified through contact force–displacement experiments and loading-unloading tests with cracked model.Finally,the contact model was tested through simulations of rock mechanics experiments.The results indicate that the contact model can effectively simulate the axial and lateral strain laws of rocks simultaneously and has a relatively good reproduction of the bi-modularity of rocks.展开更多
Real-time assessment of subgrade compaction quality poses a significant challenge in the implementation of intelligent compaction(IC).Current compaction evaluation models are confined to specific scenarios and lack ro...Real-time assessment of subgrade compaction quality poses a significant challenge in the implementation of intelligent compaction(IC).Current compaction evaluation models are confined to specific scenarios and lack robustness.This study proposes a subgrade compaction strategy that utilizes a heterogeneous dataset to estimate compaction quality across diverse scenarios while maintaining model accuracy.Field compaction tests are conducted in four distinct scenarios,considering various construction parameters.Compaction models are developed using several machine learning algorithms.The datasets are thoroughly assessed in terms of quality,diversity and similarity.The proposed model exhibits good performance in new scenarios by incorporating an additional 5%e8%of new data for retraining.The model's generalization capability is enhanced by conducting a limited number of field tests,which are labor-saving and time-efficient.The model's accuracy consistently improves across diverse scenarios and optimal algorithms.The proposed compaction strategy adopts a physics-and-data dual-driven approach,aimed at practical engineering applications and guiding the compaction procedure.展开更多
In this paper,the authors study the fractional Calderon type commutator T_(Ω,α)^(A)and its maximal operator M_(Ω,α)^(A)with kernels having some kinds of Log-type Dini-condition and obtain the compactness on Morrey...In this paper,the authors study the fractional Calderon type commutator T_(Ω,α)^(A)and its maximal operator M_(Ω,α)^(A)with kernels having some kinds of Log-type Dini-condition and obtain the compactness on Morrey spaces L^(p,λ)(R^(n)).展开更多
We present a compact cold atom platform where an optical grating chip and planar coil chip are placed inside a compact vacuum chamber to create a magneto-optical trap.This approach significantly reduces the system vol...We present a compact cold atom platform where an optical grating chip and planar coil chip are placed inside a compact vacuum chamber to create a magneto-optical trap.This approach significantly reduces the system volume to about 20×20×20 cm^(3) compared to conventional vacuum systems and offers greater flexibility in accessing the trapped atoms.We demonstrate the trapping of 3×10^(5) cold rubidium atoms at a temperature of 100μK in a vacuum pressure below 10^(−7) mbar.The simplified optical geometry,low power consumption,and high degree of integration make this a promising platform for portable and versatile cold-atom devices in quantum sensing,timing,and information processing.展开更多
Purpose-The indoor vibration compaction test(IVCT)was a key step in controlling the compaction quality for high-speed railway graded aggregate(HRGA),which currently had a research gap on the assessment indicators and ...Purpose-The indoor vibration compaction test(IVCT)was a key step in controlling the compaction quality for high-speed railway graded aggregate(HRGA),which currently had a research gap on the assessment indicators and compaction parameters.Design/methodology/approach-To address these issues,a novel multi-indicator IVCT method was proposed,including physical indicator dry density(ρd)and mechanical indicators dynamic stiffness(Krb)and bearing capacity coefficient(K20).Then,a series of IVCTs on HRGA under different compaction parameters were conducted with an improved vibration compactor,which could monitor the physical-mechanical indicators in real-time.Finally,the optimal vibration compaction parameters,including the moisture content(ω),the diameter-to-maximum particle size ratio(Rd),the thickness-to-maximum particle size ratio(Rh),the vibration frequency(f),the vibration mass(Mc)and the eccentric distance(re),were determined based on the evolution characteristics for the physical-mechanical indicators during compaction.Findings-All results indicated that theρd gradually increased and then stabilized,and the Krb initially increased and then decreased.Moreover,the inflection time of the Krb was present as the optimal compaction time(Tlp)during compaction.Additionally,optimal compaction was achieved whenωwas the water-holding content after mud pumping,Rd was 3.4,Rh was 3.5,f was the resonance frequency,and the ratio between the excitation force and the Mc was 1.8.Originality/value-The findings of this paper were significant for the quality control of HRGA compaction.展开更多
Ground Penetrating Radar(GPR)is a widely used method that is non-destructive for underground or subsurface detection.It is used in various fields and has proved to be reliable and effective.This research focuses on de...Ground Penetrating Radar(GPR)is a widely used method that is non-destructive for underground or subsurface detection.It is used in various fields and has proved to be reliable and effective.This research focuses on detecting the presence of air cavities using GPR and analyzing the radargram output based on the compactness of soil and different frequencies.The compactness is used to illustrate the presence of cavities underground artificially.The research examines how variations in the compactness of soil affect the radargram response in showing the presence of cavities using different frequencies.Experimental results demonstrate that lower permittivity materials enhance signal penetration but reduce reflection contrast,whereas higher permittivity materials result in stronger reflections,improving cavity detection.The findings highlight the importance of frequency selection and material properties in optimizing GPR surveys for subsurface anomaly detection,and by having artificially created cavities,the results can be studied to see the changes.展开更多
As organic thin film transistors(OTFTs)are set to play a crucial role in flexible and cost-effective electronic applica-tions,this paper investigates a high-mobility 6,13-bis(triisopropylsilylethynyl)pentacene(TIPS-pe...As organic thin film transistors(OTFTs)are set to play a crucial role in flexible and cost-effective electronic applica-tions,this paper investigates a high-mobility 6,13-bis(triisopropylsilylethynyl)pentacene(TIPS-pentacene)OTFT for use in flexi-ble electronics.The development of such high-mobility devices necessitates precise device modeling to support technology opti-misation and circuit design.The details of numerical simulation technique is discussed,in which,the electrical behavior of the device is well captured by fine tuning basic semiconductor equations.This technology computer-aided design(TCAD)has been validated with exprimental data.In addition,we have discussed about compact model fitting of the devices as well as parameter extraction procedure employed.This includes verification of Silvaco ATLAS finite element method(FEM)based results against experimental data gained from fabricated OTFT devices.Simulations for p-type TFT-based inverter are also per-formed to assess the performance of compact model in simple circuit simulation.展开更多
In this study,compacted loess samples with varying compaction water content but identical dry density were prepared to investigate the evolution of their hydraulic conductivity and compression behavior.Additionally,en...In this study,compacted loess samples with varying compaction water content but identical dry density were prepared to investigate the evolution of their hydraulic conductivity and compression behavior.Additionally,environmental scanning electron microscopy(ESEM)and nuclear magnetic resonance(NMR)analyses were conducted to gain microstructural insights into loess behavior at the laboratory scale.The results indicate that the maximum saturated hydraulic conductivity is observed at the lowest compaction water content,particularly in the early stage of permeability tests.In particular,for loess compacted at water contents below the optimum(as determined by the modified Proctor compaction test),the hydraulic conductivity decreases throughout the permeability tests.Conversely,when the water content exceeds the optimum level,the hydraulic conductivity shows an increasing trend.In terms of compression behavior,when the as-compacted samples are loaded in oedometer conditions,an increase in material compressibility is observed with increasing compaction water content.Again,a different phenomenological behavior was observed when the compaction water content exceeded the optimum,i.e.an abrupt increase in loess compressibility.ESEM tests provide microstructural confirmation of this evidence,as the surface morphology of the compacted loess changes significantly with increasing compaction water content.The microstructural evolution was also quantified in terms of area ratio using image processing software.Finally,NMR was used to quantify the intra-and inter-aggregate water at different compaction water contents,once again highlighting a threshold for the presence or absence of inter-aggregate water similar to the optimum water content.展开更多
Myelin formation is considered the last true“invention”in the evolution of vertebrate nervous system cell structure.The rapid jumping pulse propagation achieved by myelin enables the high conduction speed that is th...Myelin formation is considered the last true“invention”in the evolution of vertebrate nervous system cell structure.The rapid jumping pulse propagation achieved by myelin enables the high conduction speed that is the basis of human movement,sensation,and cognitive function.As a key structure in the brain,white matter is the gathering place of myelin.However,with age,white matter-associated functions become abnormal and a large number of myelin sheaths undergo degenerative changes,causing serious neurological and cognitive disorders.Despite the extensive time and effort invested in exploring myelination and its functions,numerous unresolved issues and challenges persist.In-depth exploration of the functional role of myelin may bring new inspiration for the treatment of central nervous system(CNS)diseases and even mental illnesses.In this study,we conducted a comprehensive examination of the structure and key molecules of the myelin in the CNS,delving into its formation process.Specifically,we propose a new hypothesis regarding the source of power for myelin expansion in which membrane compaction may serve as a driving force for myelin extension.The implications of this hypothesis could provide valuable insights into the pathophysiology of diseases involving myelin malfunction and open new avenues for therapeutic intervention in myelin-related disorders.展开更多
Increasing the sintering rate of powder compact is a critical challenge of powder metallurgical materials,and adjusting component distribution in particles aggregate present significant effect on the microstructure of...Increasing the sintering rate of powder compact is a critical challenge of powder metallurgical materials,and adjusting component distribution in particles aggregate present significant effect on the microstructure of sintered product,especially for multi-phase compact with local heterogeneity.Here,a case study of W–Ni–Co powder compact was adopted to illustrate the novel strategy to enhance the sintering of multi-phase compact with desired microstructure by adjusting the particle configurations.The plasma synthesis route was developed for the first time to independently adjust the configurations of W–Ni–Co nanopowders with core-shell and homogeneous structures,which facilitates to ascertain the sintering response induced exclusively by particle configurations.Comparison on sintering response further indicates that core-shell powder presents greatly promoted sintering than homogeneous one,and full-dense and uniform compact with grain size of 1.37μm was obtained by solid sintering,which is several to dozens of times smaller than that obtained by conventional liquid sintering.Theoretical and experimental Investigation on elemental immigration visualized the distinct mass diffusion behavior of powder compacts,and clarified the mass transport path promoted densification mechanism determined by powder configurations.Importantly,full-coherent phase interface induced superior strength and plasticity in alloy sintered using core-shell powder,which highlights the importance of microstructural regulation on improving the mechanical property that superior than most of previously reported tungsten heavy alloys.In summary,this work paves a new way for fast sintering of multi-phase compacts,and provides intrinsic understandings on densification mechanism of powder compact.展开更多
In this study,CiteSpace software is used to carry out visual analysis on the three-dimensional research literature on urban recreation space from the perspective of compact city theory in the past 20 years,exploring t...In this study,CiteSpace software is used to carry out visual analysis on the three-dimensional research literature on urban recreation space from the perspective of compact city theory in the past 20 years,exploring the scientific development trend and research hotspots in this field.The results show that the number of published documents shows a fluctuating upward trend,and the significant growth rate reflects the role of policy orientation in promoting the concept of compact city.The co-occurrence analysis of keywords reveals the research hotspots of“compact city”,“recreation space”and“urban park”,while the emergence of new keywords such as“vertical city”and“spatial justice”indicates the new trend of recent research.The cluster analysis and timeline map further show the evolution of research themes,with“compact city”being the largest cluster and having rich connections with other themes such as“urban design”and“urban park”.展开更多
Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonitebased buffer,backfill,and sealing systems in deep geological dispos...Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonitebased buffer,backfill,and sealing systems in deep geological disposal of high-level radioactive wastes.Motivated by such applications,most past experimental studies were focused on highly compacted and high-quality bentonite.Such degrees of dry densities may not be economically or technically feasible for other emerging applications,including as an alternative material to cement in plugging and abandonment of wells.A bespoke high-pressure high-temperature constant rate of strain(CRS)apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro-mechanical response of compacted bentonite to elevated temperatures.Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities(1.1,1.4,and 1.7 Mg/m^(3))and temperatures between 20 and 80℃.The results show that temperature increase leads to the decrease of swelling pressure for all studied densities.Larger reductions of swelling pressure were observed with increasing dry densities,suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay.The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high-density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.展开更多
A thin compact broadband coplanarfed rectangular-ring monopole antenna parasiticallyloaded by three nested concentric rectangle rings and aπ-shaped stub is proposed suitable for modern communication needs.It has an o...A thin compact broadband coplanarfed rectangular-ring monopole antenna parasiticallyloaded by three nested concentric rectangle rings and aπ-shaped stub is proposed suitable for modern communication needs.It has an overall area of only 25 mm×6 mm(0.29λ_(0)×0.07λ_(0)at 3.5 GHz),which can be the base radiating element of the MIMO array,being easily integrated into any wireless device.Its measured(simulated)fractional bandwidth is 24.6%(31.6%)ranging from 3.25(3.09)to 4.16(4.25)GHz,being applicable to the 5G N48,N77,and N78 bands.Practical guidelines are also provided to make the proposed design operate on some other additional 5G bands(e.g.,N41 or N46)without compromising its overall size.As far as the radiation properties are concerned,the antenna with such small dimensions radiates nearly bidirectionally and omnidirectionally in the E-and H-plane,respectively,and has an average measured(simulated)peak realized gain of-0.1(1.8)dBi over the band of interest.The proposed antenna is wideband,physically small and relatively easy to manufacture,making it straightforward to integrate with the RF electronics in IoT sensors.展开更多
基金funded by the National Natural Science Foundation of China(32471824,32171746,31870522,42477227,and 32560282)the leading talents of basic research in Henan Province(24XM0375)+6 种基金Excellent Youth Creative Research Group Project in Henan Province(252300421002)Foreign Scientists Studio in Henan Province(GZS2025011)MOHRSS National Foreign Expert Individual Projectsand(110000264820258001)Natural Science Foundation of Henan(242300420604)supported by the Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control(2023B1212060002)the High-level University Special Fund(G03050K001)the China Postdoctoral Science Foundation(No.2021M690922).
文摘Soil compaction often imposes stress on root development and plant survival.However,root anatomical responses that enable persistent root growth and functioning under soil compaction remain unclear.We grew 10 herbaceous species differing substantially in lateral root diameter,in soils with low(1.0 g cm^(-3))and high(1.4 g cm^(-3))bulk density,and assessed root traits including root biomass,anatomical structures,and respiration rates.Greater root thickening upon soil compaction was found in species with thicker first-order lateral roots,mainly due to larger cortical cell size.Both xylem vessel diameter and wall thickness increased more in compacted soils in these species.Despite these anatomical shifts,root respiration rate responded little to soil compaction across most species,likely due to the opposite investment in cortical cells and xylem vessels.Notably,root biomass,independent of root respiration rate and anatomical structures,determined whole-plant growth under soil compaction.Our study reveals two independent strategies of root response to soil compaction:anatomical remodeling for mechanical and metabolic maintenance,and root biomass investment for resource acquisition.These findings offer new insights for breeding and selecting species tolerant to soil compaction and highlight multidimensional strategies of plant adaptation to physical stress.
基金supported in part by the National Natural Science Foundation of China Grant 11962006the Natural Science Foundation of Jiangxi Province of China Grant 20232BAB204067.
文摘Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.
基金funded by the National Natural Science Foundation of China(Grand No.52325904)National Key Research and Development Program of China(Grant No.2023YFB2390200)the National Natural Science Foundation of China(Grant No.52309134).
文摘Laser-assisted drilling combined with full-size polycrystalline diamond compact(PDC)bit is considered a feasible solution to enhance the drilling performance of engineering machinery.In this method,determining the optimal collaborative control parameters that support rapid drilling is crucial for improving the combined performance.This study used average drilling speed,average torque,and total specificenergy for quantitative analysis to characterize the efficiencyand economy of combined rock breaking.Given the advantage of the response surface methodology in providing high-precision predictions with limited experimental data,regression models of the average drilling speed,average torque,and total specificenergy were established.The results showed that as the laser power and irradiation time increased,the average drilling speed firstincreased rapidly and then leveled off,while the average torque decreased sharply before decelerating.The total specificenergy initially decreased and then increased,with the combined drilling outperforming conventional mechanical drilling within specific parameter ranges.As the weight on bit increased,both the average torque and total specificenergy first decreased and then increased.With rising rotating speed,the average torque exhibited a trend of initial increase,then decrease,and finalincrease,whereas the total specificenergy increased slowly at firstand then sharply.Both parameters exhibited optimal values at which the average torque and total specific energy remained at minimal levels.For granite combined drilling,the optimal performance was achieved at a laser power of 3000 W,irradiation time of 31 s,the weight on bit of 2.4 kN,and the rotating speed of 97 r/min.
基金supported by the Innovation Team in Key Areas of the Innovation Talent Promotion Plan(2021)of MOST,Chinathe National Natural Science Foundation of China(Nos.52473078,52071239,52311530074)the Cultivation Program of Wuhan Institute of Photochemistry and Technology(No.GHY2023KF004).
文摘Coating uniform,compact and thin nanoshells on micro-sized particles is critical to various applications including anticorrosive broadband microwave absorbing materials(MAMs),yet effective processing methods remain lacking.In this work,a turbulent sol-gel method is developed to coat the desired SiO2 nanoshells on flaky carbonyl iron(FCI)particles.The adding millimeter-sized zirconia balls,driven by the orbital shaking,squeeze the solution and create significant relative motion between the liquid and balls,which generates turbulent flows.This significantly promotes the heterogeneous nucleation rate and high nucleation density,ultimately forming highly compact and uniform SiO2 nanoshells covering FCI particles to enhance the electromagnetic absorption and anticorrosion properties.The as-obtained core-shell particles minimize the interface polarization and retain high magnetic loss,resulting in an improved impedance matching and a reflection loss<−10 dB with a bandwidth of 6.5 GHz at a thin thickness of 1 mm.Moreover,they also show a substantial order-of-magnitude improvement in anticorrosion performance.This work provides a promising method to fabricate anticorrosive,broadband and thin-thickness MAMs.The turbulent sol-gel method developed herein offers a facile and effective approach for fabricating uniform compact nanoshells on micro-sized particles.
基金supported by the Natural Science Foundation of Heilongjiang Province(No.ZD2021E006)the National Natural Science Foundation of China(Nos.52174075 and 52074110).
文摘The models constructed by particle flow simulation method can effectively simulate the heterogeneous substance characteristics and failure behaviors of rocks.However,existing contact models overlook the rock cracks,and the various simulation methods that do consider cracks still exhibit certain limitations.In this paper,based on Flat-Joint model and Linear Parallel Bond model,a crack contact model considering linked substance in the crack is proposed by splitting the crack contact into two portions:linked portion and unlinked portion for calculation.The new contact model considers the influence of crack closure on the contact force-displacement law.And a better compressive tensile strength ratio(UCS/T)was obtained by limiting the failure of the contact bond to be solely controlled by the contact force and moment of the linked portion.Then,by employing the FISH Model tool within the Particle Flow Code,the contact model was constructed and verified through contact force–displacement experiments and loading-unloading tests with cracked model.Finally,the contact model was tested through simulations of rock mechanics experiments.The results indicate that the contact model can effectively simulate the axial and lateral strain laws of rocks simultaneously and has a relatively good reproduction of the bi-modularity of rocks.
基金supported by the National Natural Science Foundation of China(Grant Nos.52038005 and 52278342)the Natural Science Foundation of Tianjin Municipal(Grant No.23JCJQJC00160).
文摘Real-time assessment of subgrade compaction quality poses a significant challenge in the implementation of intelligent compaction(IC).Current compaction evaluation models are confined to specific scenarios and lack robustness.This study proposes a subgrade compaction strategy that utilizes a heterogeneous dataset to estimate compaction quality across diverse scenarios while maintaining model accuracy.Field compaction tests are conducted in four distinct scenarios,considering various construction parameters.Compaction models are developed using several machine learning algorithms.The datasets are thoroughly assessed in terms of quality,diversity and similarity.The proposed model exhibits good performance in new scenarios by incorporating an additional 5%e8%of new data for retraining.The model's generalization capability is enhanced by conducting a limited number of field tests,which are labor-saving and time-efficient.The model's accuracy consistently improves across diverse scenarios and optimal algorithms.The proposed compaction strategy adopts a physics-and-data dual-driven approach,aimed at practical engineering applications and guiding the compaction procedure.
文摘A survey of recent progress on the multiplicity and stability problems for closed characteristics on compact convex hypersurfaces in R^(2n) is given.
文摘In this paper,the authors study the fractional Calderon type commutator T_(Ω,α)^(A)and its maximal operator M_(Ω,α)^(A)with kernels having some kinds of Log-type Dini-condition and obtain the compactness on Morrey spaces L^(p,λ)(R^(n)).
基金supported by the National Key R&D Program(Grant Nos.2021YFA1402004 and 2021YFF0603701)the National Natural Science Foundation of China(Grant Nos.12134014,U21A20433,U21A6006,and 92265108)+1 种基金the Fundamental Research Funds for the Central Universitiesthe University of Science and Technology of China(USTC)Research Funds of the Double First-Class Initiative。
文摘We present a compact cold atom platform where an optical grating chip and planar coil chip are placed inside a compact vacuum chamber to create a magneto-optical trap.This approach significantly reduces the system volume to about 20×20×20 cm^(3) compared to conventional vacuum systems and offers greater flexibility in accessing the trapped atoms.We demonstrate the trapping of 3×10^(5) cold rubidium atoms at a temperature of 100μK in a vacuum pressure below 10^(−7) mbar.The simplified optical geometry,low power consumption,and high degree of integration make this a promising platform for portable and versatile cold-atom devices in quantum sensing,timing,and information processing.
基金funded by the National Key R&D Program“Transportation Infrastructure”project(No.2022YFB2603400)the Technology Research and Development Plan Program of China State Railway Group Co.,Ltd.(No.Q2024T001)the National project pre research project of Suzhou City University(No.2023SGY019).
文摘Purpose-The indoor vibration compaction test(IVCT)was a key step in controlling the compaction quality for high-speed railway graded aggregate(HRGA),which currently had a research gap on the assessment indicators and compaction parameters.Design/methodology/approach-To address these issues,a novel multi-indicator IVCT method was proposed,including physical indicator dry density(ρd)and mechanical indicators dynamic stiffness(Krb)and bearing capacity coefficient(K20).Then,a series of IVCTs on HRGA under different compaction parameters were conducted with an improved vibration compactor,which could monitor the physical-mechanical indicators in real-time.Finally,the optimal vibration compaction parameters,including the moisture content(ω),the diameter-to-maximum particle size ratio(Rd),the thickness-to-maximum particle size ratio(Rh),the vibration frequency(f),the vibration mass(Mc)and the eccentric distance(re),were determined based on the evolution characteristics for the physical-mechanical indicators during compaction.Findings-All results indicated that theρd gradually increased and then stabilized,and the Krb initially increased and then decreased.Moreover,the inflection time of the Krb was present as the optimal compaction time(Tlp)during compaction.Additionally,optimal compaction was achieved whenωwas the water-holding content after mud pumping,Rd was 3.4,Rh was 3.5,f was the resonance frequency,and the ratio between the excitation force and the Mc was 1.8.Originality/value-The findings of this paper were significant for the quality control of HRGA compaction.
文摘Ground Penetrating Radar(GPR)is a widely used method that is non-destructive for underground or subsurface detection.It is used in various fields and has proved to be reliable and effective.This research focuses on detecting the presence of air cavities using GPR and analyzing the radargram output based on the compactness of soil and different frequencies.The compactness is used to illustrate the presence of cavities underground artificially.The research examines how variations in the compactness of soil affect the radargram response in showing the presence of cavities using different frequencies.Experimental results demonstrate that lower permittivity materials enhance signal penetration but reduce reflection contrast,whereas higher permittivity materials result in stronger reflections,improving cavity detection.The findings highlight the importance of frequency selection and material properties in optimizing GPR surveys for subsurface anomaly detection,and by having artificially created cavities,the results can be studied to see the changes.
基金The DST government of India is appreciated by the researchers for giving them the early career research grant under the project ECR/2017/000179。
文摘As organic thin film transistors(OTFTs)are set to play a crucial role in flexible and cost-effective electronic applica-tions,this paper investigates a high-mobility 6,13-bis(triisopropylsilylethynyl)pentacene(TIPS-pentacene)OTFT for use in flexi-ble electronics.The development of such high-mobility devices necessitates precise device modeling to support technology opti-misation and circuit design.The details of numerical simulation technique is discussed,in which,the electrical behavior of the device is well captured by fine tuning basic semiconductor equations.This technology computer-aided design(TCAD)has been validated with exprimental data.In addition,we have discussed about compact model fitting of the devices as well as parameter extraction procedure employed.This includes verification of Silvaco ATLAS finite element method(FEM)based results against experimental data gained from fabricated OTFT devices.Simulations for p-type TFT-based inverter are also per-formed to assess the performance of compact model in simple circuit simulation.
基金the China Postdoctoral Science Foundation(Grant No.2024MD753992)Shaanxi Geotechnical Mechanics and Engineering Young Talent Support Program Project(Grant No.YESS2024005)the National Natural Science Foundation of China(Grant No.41931285).
文摘In this study,compacted loess samples with varying compaction water content but identical dry density were prepared to investigate the evolution of their hydraulic conductivity and compression behavior.Additionally,environmental scanning electron microscopy(ESEM)and nuclear magnetic resonance(NMR)analyses were conducted to gain microstructural insights into loess behavior at the laboratory scale.The results indicate that the maximum saturated hydraulic conductivity is observed at the lowest compaction water content,particularly in the early stage of permeability tests.In particular,for loess compacted at water contents below the optimum(as determined by the modified Proctor compaction test),the hydraulic conductivity decreases throughout the permeability tests.Conversely,when the water content exceeds the optimum level,the hydraulic conductivity shows an increasing trend.In terms of compression behavior,when the as-compacted samples are loaded in oedometer conditions,an increase in material compressibility is observed with increasing compaction water content.Again,a different phenomenological behavior was observed when the compaction water content exceeded the optimum,i.e.an abrupt increase in loess compressibility.ESEM tests provide microstructural confirmation of this evidence,as the surface morphology of the compacted loess changes significantly with increasing compaction water content.The microstructural evolution was also quantified in terms of area ratio using image processing software.Finally,NMR was used to quantify the intra-and inter-aggregate water at different compaction water contents,once again highlighting a threshold for the presence or absence of inter-aggregate water similar to the optimum water content.
基金supported by the National Natural Science Foundation of China(No.U21A20400)the Natural Science Foundation of Beijing(No.8217153264)the Key Project of Beijing University of Chinese Medicine(No.2022-JYB-JBZR-004),China.
文摘Myelin formation is considered the last true“invention”in the evolution of vertebrate nervous system cell structure.The rapid jumping pulse propagation achieved by myelin enables the high conduction speed that is the basis of human movement,sensation,and cognitive function.As a key structure in the brain,white matter is the gathering place of myelin.However,with age,white matter-associated functions become abnormal and a large number of myelin sheaths undergo degenerative changes,causing serious neurological and cognitive disorders.Despite the extensive time and effort invested in exploring myelination and its functions,numerous unresolved issues and challenges persist.In-depth exploration of the functional role of myelin may bring new inspiration for the treatment of central nervous system(CNS)diseases and even mental illnesses.In this study,we conducted a comprehensive examination of the structure and key molecules of the myelin in the CNS,delving into its formation process.Specifically,we propose a new hypothesis regarding the source of power for myelin expansion in which membrane compaction may serve as a driving force for myelin extension.The implications of this hypothesis could provide valuable insights into the pathophysiology of diseases involving myelin malfunction and open new avenues for therapeutic intervention in myelin-related disorders.
基金supported by the National Natural Science Foundation of China(No.52130407,52174342,52441408)Beijing Natural Science Foundation(No.2232044,IS23050).
文摘Increasing the sintering rate of powder compact is a critical challenge of powder metallurgical materials,and adjusting component distribution in particles aggregate present significant effect on the microstructure of sintered product,especially for multi-phase compact with local heterogeneity.Here,a case study of W–Ni–Co powder compact was adopted to illustrate the novel strategy to enhance the sintering of multi-phase compact with desired microstructure by adjusting the particle configurations.The plasma synthesis route was developed for the first time to independently adjust the configurations of W–Ni–Co nanopowders with core-shell and homogeneous structures,which facilitates to ascertain the sintering response induced exclusively by particle configurations.Comparison on sintering response further indicates that core-shell powder presents greatly promoted sintering than homogeneous one,and full-dense and uniform compact with grain size of 1.37μm was obtained by solid sintering,which is several to dozens of times smaller than that obtained by conventional liquid sintering.Theoretical and experimental Investigation on elemental immigration visualized the distinct mass diffusion behavior of powder compacts,and clarified the mass transport path promoted densification mechanism determined by powder configurations.Importantly,full-coherent phase interface induced superior strength and plasticity in alloy sintered using core-shell powder,which highlights the importance of microstructural regulation on improving the mechanical property that superior than most of previously reported tungsten heavy alloys.In summary,this work paves a new way for fast sintering of multi-phase compacts,and provides intrinsic understandings on densification mechanism of powder compact.
基金Sponsored by the Project of Sichuan Landscape and Recreation Research Center(JGYQ2020037).
文摘In this study,CiteSpace software is used to carry out visual analysis on the three-dimensional research literature on urban recreation space from the perspective of compact city theory in the past 20 years,exploring the scientific development trend and research hotspots in this field.The results show that the number of published documents shows a fluctuating upward trend,and the significant growth rate reflects the role of policy orientation in promoting the concept of compact city.The co-occurrence analysis of keywords reveals the research hotspots of“compact city”,“recreation space”and“urban park”,while the emergence of new keywords such as“vertical city”and“spatial justice”indicates the new trend of recent research.The cluster analysis and timeline map further show the evolution of research themes,with“compact city”being the largest cluster and having rich connections with other themes such as“urban design”and“urban park”.
基金University of Manchester and the China Scholarship Council,Royal Society,UK,Grant/Award Number:IECNSFC211366National Natural Science Foundation of China,Grant/Award Numbers:5247415,52174133Natural Science Foundation of Jiangsu Province of China,Grant/Award Number:BK20240107。
文摘Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonitebased buffer,backfill,and sealing systems in deep geological disposal of high-level radioactive wastes.Motivated by such applications,most past experimental studies were focused on highly compacted and high-quality bentonite.Such degrees of dry densities may not be economically or technically feasible for other emerging applications,including as an alternative material to cement in plugging and abandonment of wells.A bespoke high-pressure high-temperature constant rate of strain(CRS)apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro-mechanical response of compacted bentonite to elevated temperatures.Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities(1.1,1.4,and 1.7 Mg/m^(3))and temperatures between 20 and 80℃.The results show that temperature increase leads to the decrease of swelling pressure for all studied densities.Larger reductions of swelling pressure were observed with increasing dry densities,suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay.The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high-density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.
文摘A thin compact broadband coplanarfed rectangular-ring monopole antenna parasiticallyloaded by three nested concentric rectangle rings and aπ-shaped stub is proposed suitable for modern communication needs.It has an overall area of only 25 mm×6 mm(0.29λ_(0)×0.07λ_(0)at 3.5 GHz),which can be the base radiating element of the MIMO array,being easily integrated into any wireless device.Its measured(simulated)fractional bandwidth is 24.6%(31.6%)ranging from 3.25(3.09)to 4.16(4.25)GHz,being applicable to the 5G N48,N77,and N78 bands.Practical guidelines are also provided to make the proposed design operate on some other additional 5G bands(e.g.,N41 or N46)without compromising its overall size.As far as the radiation properties are concerned,the antenna with such small dimensions radiates nearly bidirectionally and omnidirectionally in the E-and H-plane,respectively,and has an average measured(simulated)peak realized gain of-0.1(1.8)dBi over the band of interest.The proposed antenna is wideband,physically small and relatively easy to manufacture,making it straightforward to integrate with the RF electronics in IoT sensors.
