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
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
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
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
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
This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common...This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common miniaturization technique to replace the conventional quarter-wavelength transmission line with an equivalent low-pass filter loaded with parallel coupled line and radial stubs. Since the latter leads to produce higher order harmonics, parasitic open-ended stubs are then properly introduced in the structure not only to overcome the issue but also to produce controllable transmission zeros. A versatile analytical model is also developed taking into account manufacturing restrictions, which makes it possible to extract the physical parameters of the coupler unit-cell for a given desired compactness percentage with respect to the conventional rat-race coupler. A prototype is fabricated and measured to validate the design,demonstrating the predicted behavior fairly achieved by numerical analysis. A significant size reduction of about 86.1% was achieved compared to the conventional design, while effectively suppressing higher order modes up to 23.4 GHz(including the 13th harmonic based on |S11|>-5 dB and |S21|<-17 dB)with high isolation level(|S41|<-17 dB) between the ports.展开更多
In the present article,we introduce a completely new regular model for static,spherically symmetric celestial fluid spheres in embedding classⅠspacetime.In this regard,needfully,we propose a new suitable metric poten...In the present article,we introduce a completely new regular model for static,spherically symmetric celestial fluid spheres in embedding classⅠspacetime.In this regard,needfully,we propose a new suitable metric potential e^(λ(r))to generate the present model.The various analyses on energy density,pressure,anisotropic factor,mass,compactness parameter,redshift,and energy condition make sure the model is physically viable on the ground of model stars Vela X-1,Cen X-3,SMC X-4,and LMC X-4.The reported solutions also respect the equilibrium state by satisfying the Tolman-Oppenheimer-Volkoff(TOV)equation and ensure stability by satisfying the causality condition,condition on the adiabatic index,and Harrison-Zeldovich-Novikov condition.The generated M-R graph matches the ranges of masses and radii for the model compact stars.Additionally,this study provides estimates of the moment of inertia based on the I-M graph.展开更多
By combining a concave-convex multi-pass cavity with solid-state nonlinear media for spectral broadening and a post-compression grating setup,we generated femtosecond pulses with high peak power density.Compared to th...By combining a concave-convex multi-pass cavity with solid-state nonlinear media for spectral broadening and a post-compression grating setup,we generated femtosecond pulses with high peak power density.Compared to the other traditional pulse compression technologies,the configuration is very compact with large tolerance for beam direction and spot size.The pulses with an average power of 80 W,a pulse width of 10.7 ps,and a repetition rate of 500 kHz are compressed to 842 fs with the configuration,and the compressed pulse duration approaches the Fourier transform limited pulse duration of 707 fs.展开更多
Letϕbe a smooth radial weight that decays faster than the class Gaussian ones.We obtain certain estimates for the reproducing kernels and the Lp-estimates for solutions of theδ-equation on the weighted Fock spaces F_...Letϕbe a smooth radial weight that decays faster than the class Gaussian ones.We obtain certain estimates for the reproducing kernels and the Lp-estimates for solutions of theδ-equation on the weighted Fock spaces F_(ϕ)^(p)(1≤p≤∞),which extends the classical Hörmander Theorem.Furthermore,for a suitable f,we completely characterize the boundedness and compactness of the Hankel operator H_(f):F_(ϕ)^(p)→L^(q)(C,e^(qϕ(·))dm)for all possible 1≤p,q<∞and also characterize the Schatten-p class Hankel operator Hf from F_(ϕ)^(2)to L^(2)(C,E^(-2ϕ)dm) for all 0<p<∞. As an application, we give a complete characterization of the simultaneously bounded, compact and Schatten-p classes Hankel operators H_(f) and h_(f)^(-) on F_(ϕ)^(2).展开更多
Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were condu...Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.展开更多
Recently,Choe-Koo-Wang(J Funct Anal,2020,278)demonstrated the rigid phenomenon:The compact linear combination of composition operators under the Coefficient Non-cancellation Condition(CNC),implies that each difference...Recently,Choe-Koo-Wang(J Funct Anal,2020,278)demonstrated the rigid phenomenon:The compact linear combination of composition operators under the Coefficient Non-cancellation Condition(CNC),implies that each difference is compact on the weighted Bergman space in the unit disk.Motivated by the subtle connection of composition operator theory on the weighted Bergman spaces,Korenblum spaces and bounded holomorphic function spaces,we first explore the rigid phenomenon which also holds on the Korenblum space over the unit ball.Furthermore,we discuss which difference of composition operators is compact when the compact combination of composition operators does not satisfy the condition(CNC)on Korenblum spaces and bounded holomorphic function spaces over the unit ball setting.展开更多
The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissip...The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissipation(LED)law,a novel compressive damage constitutive model for brittle coal is proposed.Utilizing the energy-defined damage method for mate-rials,the LED law is innovatively introduced to accurately characterize the energy dissipation during the loading process,and a novel formula for characterizing the damage variable of brittle coal is proposed.On this basis,considering that the constitutive model based on the hypothesis of strain equivalence is incapable of accurately describing the compaction effect exhibited by coal material during the compression process,a correction coefficient is proposed and apply it in the novel damage constitutive model.The established conventional monotone loading and single-cyclic loading-unloading uniaxial compression damage constitutive models have been validated using experimental data from cylindrical and cuboid coal specimens.In addition,compared with the constitutive model obtained via the traditional energy calculation method based on the hypothesis that the unloading curve is a straight line,the constitutive model employing LED law can describe the stress-strain state of brittle coal more precisely.This approach introduces a new perspective and enhances the convenience for constructing the constitutive model based on energy theory.展开更多
Deep geological repository is typically situated at depths ranging from several hundred to 1000 m below ground,making bentonite engineered barrier potentially vulnerable to high water pressure and even inducing hydrau...Deep geological repository is typically situated at depths ranging from several hundred to 1000 m below ground,making bentonite engineered barrier potentially vulnerable to high water pressure and even inducing hydraulic fracturing.This study conducted injection tests on compacted GMZ(Gaomiaozi)bentonite with a self-developed visualization set-up.The objective was to unveil the roles of dry density,water content,and pressurization rate in hydraulic fracturing from the perspective of fracturing macromorphological dynamics and breakthrough characteristics.Moreover,the relationships between breakthrough characteristics and microstructure were examined by MIP(mercury intrusion porosimetry)analysis.Results showed that the fracturing dynamics were characterized by three stages:hydration,cracking,and fracturing stages.Compared to water content and pressurization rate,dry density exerted more pronounced effects on these stages.Increasing dry density can lead to an expansion of circular hydration zone,a more complex cracking network,and a change in fracturing patterns from long and clear to short and fuzzy.In terms of breakthrough characteristics,the breakthrough pressure was positively correlated with dry density and negatively correlated with water content.Interestingly,there is a good and unique logarithmic correlation between the breakthrough pressure and the ratio eM/em of inter-aggregate void ratio and intra-aggregate void ratio,regardless of dry density and water content.Within a certain range(i.e.200-50 kPa/min),breakthrough pressure showed slight dependency on pressurization rate.Nevertheless,an extremely low pressurization rate of 20 kPa/min caused a transition for the specimen from quasi-brittle to plastic state owning to more water infiltration,thereby hindering fracture initiation and propagation.展开更多
Optimization and simplification of optical systems represent a milestone in advancing the development of handheld and portable laser-induced breakdown spectroscopy(LIBS)systems towards smaller,more integrated forms.Th...Optimization and simplification of optical systems represent a milestone in advancing the development of handheld and portable laser-induced breakdown spectroscopy(LIBS)systems towards smaller,more integrated forms.This research,for the first time,conducted a comprehensive optimization design and comparative analysis of three compact LIBS system optical paths:the paraxial optical path(OP),the off-axis OP,and the reflective OP.The differences in spectral intensity and stability among these paths were revealed,providing a scientific basis for selecting the optimal OP for LIBS systems.The research found that the paraxial OP excels in spectral performance and quantitative analysis accuracy,making it the preferred choice for compact LIBS systems.Specifically,the paraxial OP significantly enhances spectral intensity,achieving a 6 times improvement over the off-axis OP and an even more remarkable 150 times increase compared to the reflective OP,greatly enhancing detection sensitivity.Additionally,the relative standard deviation,spectral stability index,maintains a consistently low level,ranging from 10.9%to 13.4%,significantly outperforming the other two OPs and ensuring the reliability of analytical results.In the field of quantitative analysis,the paraxial OP also demonstrates higher accuracy,precision,and sensitivity,comparing to other OPs.The quantitative analysis models for Si,Cu,and Ti elements exhibit excellent fitting,providing users with high-quality quantitative analysis results that are of great significance for applications in material science,environmental monitoring,industrial inspection,and other fields.In summary,this study not only confirms the enormous application potential of the paraxial OP in compact LIBS systems but also provides valuable practical experience and theoretical support for the miniaturization and integration of LIBS systems.Looking ahead,with continuous technological advancements,the design of the paraxial OP is expected to further propel the widespread adoption of LIBS technology in portable,on-site detection applications.展开更多
The compact torus injector(CTI)for the central fueling of the EAST tokamak has undergone significant upgrades to enhance its injection capability.During the initial phase of the platform testing phase,EAST-CTI demonst...The compact torus injector(CTI)for the central fueling of the EAST tokamak has undergone significant upgrades to enhance its injection capability.During the initial phase of the platform testing phase,EAST-CTI demonstrated relatively low performance,with a maximum velocity of 150 km s^(−1) and a single compact torus(CT)plasma mass of 90μg[Kong D et al 2023 Plasma Sci.Technol.25065601].These parameters were insufficient for conducting central fueling experiments on the EAST tokamak.Consequently,extensive upgrades were carried out to improve the performance of the EAST-CTI system.The compression region was extended from 280 mm to 700 mm to prevent rapid compression and deceleration of the CT plasma,along with an extension of the acceleration region to further increase the plasma acceleration.The power supply system has also been upgraded.These improvements elevated the operating voltage from 8 kV to 15 kV,increased the discharge current from 120 kA to 300 kA and enabled repetitive operation at a maximum rate of 2 Hz.As a result,significant advances in EAST-CTI performance were achieved,with the maximum velocity increasing to 330 km s^(−1) and the CT plasma density reaching 1.5×10^(22) m^(−3),thereby enhancing the system capability for future fueling experiments on EAST.This study offers valuable insights into CTI modification and the improvement of central fueling systems for prospective fusion reactors.展开更多
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.
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.
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.
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.
文摘This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common miniaturization technique to replace the conventional quarter-wavelength transmission line with an equivalent low-pass filter loaded with parallel coupled line and radial stubs. Since the latter leads to produce higher order harmonics, parasitic open-ended stubs are then properly introduced in the structure not only to overcome the issue but also to produce controllable transmission zeros. A versatile analytical model is also developed taking into account manufacturing restrictions, which makes it possible to extract the physical parameters of the coupler unit-cell for a given desired compactness percentage with respect to the conventional rat-race coupler. A prototype is fabricated and measured to validate the design,demonstrating the predicted behavior fairly achieved by numerical analysis. A significant size reduction of about 86.1% was achieved compared to the conventional design, while effectively suppressing higher order modes up to 23.4 GHz(including the 13th harmonic based on |S11|>-5 dB and |S21|<-17 dB)with high isolation level(|S41|<-17 dB) between the ports.
文摘In the present article,we introduce a completely new regular model for static,spherically symmetric celestial fluid spheres in embedding classⅠspacetime.In this regard,needfully,we propose a new suitable metric potential e^(λ(r))to generate the present model.The various analyses on energy density,pressure,anisotropic factor,mass,compactness parameter,redshift,and energy condition make sure the model is physically viable on the ground of model stars Vela X-1,Cen X-3,SMC X-4,and LMC X-4.The reported solutions also respect the equilibrium state by satisfying the Tolman-Oppenheimer-Volkoff(TOV)equation and ensure stability by satisfying the causality condition,condition on the adiabatic index,and Harrison-Zeldovich-Novikov condition.The generated M-R graph matches the ranges of masses and radii for the model compact stars.Additionally,this study provides estimates of the moment of inertia based on the I-M graph.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1604200 and 2022YFB4601101)the Beijing Municipal Commission of Science and Technology(Grant No.Z231100006623006)+1 种基金the Beijing Natural Science Foundation(Grant No.JQ21019)the National Natural Science Foundation of China(Grant Nos.12034020,11975001,12075034,and 12261131495)。
文摘By combining a concave-convex multi-pass cavity with solid-state nonlinear media for spectral broadening and a post-compression grating setup,we generated femtosecond pulses with high peak power density.Compared to the other traditional pulse compression technologies,the configuration is very compact with large tolerance for beam direction and spot size.The pulses with an average power of 80 W,a pulse width of 10.7 ps,and a repetition rate of 500 kHz are compressed to 842 fs with the configuration,and the compressed pulse duration approaches the Fourier transform limited pulse duration of 707 fs.
文摘Letϕbe a smooth radial weight that decays faster than the class Gaussian ones.We obtain certain estimates for the reproducing kernels and the Lp-estimates for solutions of theδ-equation on the weighted Fock spaces F_(ϕ)^(p)(1≤p≤∞),which extends the classical Hörmander Theorem.Furthermore,for a suitable f,we completely characterize the boundedness and compactness of the Hankel operator H_(f):F_(ϕ)^(p)→L^(q)(C,e^(qϕ(·))dm)for all possible 1≤p,q<∞and also characterize the Schatten-p class Hankel operator Hf from F_(ϕ)^(2)to L^(2)(C,E^(-2ϕ)dm) for all 0<p<∞. As an application, we give a complete characterization of the simultaneously bounded, compact and Schatten-p classes Hankel operators H_(f) and h_(f)^(-) on F_(ϕ)^(2).
基金the National Natural Science Foundation of China(Grant Nos.42172298,42002289)the Shanghai Geological Star Program for their financial support.
文摘Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.
基金supported by National Science Foundations of China(Grant No.11771340,12171373).
文摘Recently,Choe-Koo-Wang(J Funct Anal,2020,278)demonstrated the rigid phenomenon:The compact linear combination of composition operators under the Coefficient Non-cancellation Condition(CNC),implies that each difference is compact on the weighted Bergman space in the unit disk.Motivated by the subtle connection of composition operator theory on the weighted Bergman spaces,Korenblum spaces and bounded holomorphic function spaces,we first explore the rigid phenomenon which also holds on the Korenblum space over the unit ball.Furthermore,we discuss which difference of composition operators is compact when the compact combination of composition operators does not satisfy the condition(CNC)on Korenblum spaces and bounded holomorphic function spaces over the unit ball setting.
基金supported by the National Science Fund for Distinguished Young Scholars(52225403)the National Natural Science Foundation of China(42077244).
文摘The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissipation(LED)law,a novel compressive damage constitutive model for brittle coal is proposed.Utilizing the energy-defined damage method for mate-rials,the LED law is innovatively introduced to accurately characterize the energy dissipation during the loading process,and a novel formula for characterizing the damage variable of brittle coal is proposed.On this basis,considering that the constitutive model based on the hypothesis of strain equivalence is incapable of accurately describing the compaction effect exhibited by coal material during the compression process,a correction coefficient is proposed and apply it in the novel damage constitutive model.The established conventional monotone loading and single-cyclic loading-unloading uniaxial compression damage constitutive models have been validated using experimental data from cylindrical and cuboid coal specimens.In addition,compared with the constitutive model obtained via the traditional energy calculation method based on the hypothesis that the unloading curve is a straight line,the constitutive model employing LED law can describe the stress-strain state of brittle coal more precisely.This approach introduces a new perspective and enhances the convenience for constructing the constitutive model based on energy theory.
基金supported by the National Natural Science Foundation of China(Grant Nos.42430713 and 42125701)Innovation Program of Shanghai Municipal Education Commission(Grant No.2023ZKZD26)。
文摘Deep geological repository is typically situated at depths ranging from several hundred to 1000 m below ground,making bentonite engineered barrier potentially vulnerable to high water pressure and even inducing hydraulic fracturing.This study conducted injection tests on compacted GMZ(Gaomiaozi)bentonite with a self-developed visualization set-up.The objective was to unveil the roles of dry density,water content,and pressurization rate in hydraulic fracturing from the perspective of fracturing macromorphological dynamics and breakthrough characteristics.Moreover,the relationships between breakthrough characteristics and microstructure were examined by MIP(mercury intrusion porosimetry)analysis.Results showed that the fracturing dynamics were characterized by three stages:hydration,cracking,and fracturing stages.Compared to water content and pressurization rate,dry density exerted more pronounced effects on these stages.Increasing dry density can lead to an expansion of circular hydration zone,a more complex cracking network,and a change in fracturing patterns from long and clear to short and fuzzy.In terms of breakthrough characteristics,the breakthrough pressure was positively correlated with dry density and negatively correlated with water content.Interestingly,there is a good and unique logarithmic correlation between the breakthrough pressure and the ratio eM/em of inter-aggregate void ratio and intra-aggregate void ratio,regardless of dry density and water content.Within a certain range(i.e.200-50 kPa/min),breakthrough pressure showed slight dependency on pressurization rate.Nevertheless,an extremely low pressurization rate of 20 kPa/min caused a transition for the specimen from quasi-brittle to plastic state owning to more water infiltration,thereby hindering fracture initiation and propagation.
基金financially supported by National Natural Science Foundation of China (Nos.62305392 and 62305123)Independent Research and Development Project of Naval Engineering University (No.2023504050)the Nursery Plan Project of Navel University of Engineering (2022)。
文摘Optimization and simplification of optical systems represent a milestone in advancing the development of handheld and portable laser-induced breakdown spectroscopy(LIBS)systems towards smaller,more integrated forms.This research,for the first time,conducted a comprehensive optimization design and comparative analysis of three compact LIBS system optical paths:the paraxial optical path(OP),the off-axis OP,and the reflective OP.The differences in spectral intensity and stability among these paths were revealed,providing a scientific basis for selecting the optimal OP for LIBS systems.The research found that the paraxial OP excels in spectral performance and quantitative analysis accuracy,making it the preferred choice for compact LIBS systems.Specifically,the paraxial OP significantly enhances spectral intensity,achieving a 6 times improvement over the off-axis OP and an even more remarkable 150 times increase compared to the reflective OP,greatly enhancing detection sensitivity.Additionally,the relative standard deviation,spectral stability index,maintains a consistently low level,ranging from 10.9%to 13.4%,significantly outperforming the other two OPs and ensuring the reliability of analytical results.In the field of quantitative analysis,the paraxial OP also demonstrates higher accuracy,precision,and sensitivity,comparing to other OPs.The quantitative analysis models for Si,Cu,and Ti elements exhibit excellent fitting,providing users with high-quality quantitative analysis results that are of great significance for applications in material science,environmental monitoring,industrial inspection,and other fields.In summary,this study not only confirms the enormous application potential of the paraxial OP in compact LIBS systems but also provides valuable practical experience and theoretical support for the miniaturization and integration of LIBS systems.Looking ahead,with continuous technological advancements,the design of the paraxial OP is expected to further propel the widespread adoption of LIBS technology in portable,on-site detection applications.
基金supported by the National MCF Energy R&D Program of China(Nos.2024YFE03130001 and 2024YFE03130002)the Institute of Energy,Hefei Comprehensive National Science Center(Anhui Energy Laboratory)(Nos.21KZS202 and 23KHH140)+3 种基金the University Synergy Innovation Program of Anhui Province(Nos.GXXT-2021-014 and GXXT-2021-029)National Natural Science Foundation of China(Nos.12105088 and 12305247)the Fundamental Research Funds for the Central Universities of China(No.PA2024GDSK0097)the Anhui Province Key Research and Development Plan Program(Nos.202304a05020006 and 2021006).
文摘The compact torus injector(CTI)for the central fueling of the EAST tokamak has undergone significant upgrades to enhance its injection capability.During the initial phase of the platform testing phase,EAST-CTI demonstrated relatively low performance,with a maximum velocity of 150 km s^(−1) and a single compact torus(CT)plasma mass of 90μg[Kong D et al 2023 Plasma Sci.Technol.25065601].These parameters were insufficient for conducting central fueling experiments on the EAST tokamak.Consequently,extensive upgrades were carried out to improve the performance of the EAST-CTI system.The compression region was extended from 280 mm to 700 mm to prevent rapid compression and deceleration of the CT plasma,along with an extension of the acceleration region to further increase the plasma acceleration.The power supply system has also been upgraded.These improvements elevated the operating voltage from 8 kV to 15 kV,increased the discharge current from 120 kA to 300 kA and enabled repetitive operation at a maximum rate of 2 Hz.As a result,significant advances in EAST-CTI performance were achieved,with the maximum velocity increasing to 330 km s^(−1) and the CT plasma density reaching 1.5×10^(22) m^(−3),thereby enhancing the system capability for future fueling experiments on EAST.This study offers valuable insights into CTI modification and the improvement of central fueling systems for prospective fusion reactors.
