Effect of pre-annealing treatment temperature on compactibility of gas-atomized Al-27%Si alloy powders was investigated. Microstructure and hardness of the annealed powders were characterized. Pre-annealing results in...Effect of pre-annealing treatment temperature on compactibility of gas-atomized Al-27%Si alloy powders was investigated. Microstructure and hardness of the annealed powders were characterized. Pre-annealing results in decreasing Al matrix hardness, dissolving of needle-like eutectic Si phase, precipitation and growth of supersaturated Si atoms, and spheroidisation of primary Si phase. Compactibility of the alloy powders is gradually improved with increasing the annealing temperature to 400 ℃. However, it decreases when the temperature is above 400 ℃ owing to the existence of Si-Si phase clusters and the densely distributed Si particles. A maximum relative density of 96.1% is obtained after annealing at 400 ℃ for 4 h. In addition, the deviation of compactibility among the pre-annealed powders reaches a maximum at a pressure of 175 MPa. Therefore, a proper pre-annealing treatment can significantly enhance the cold compactibility of gas-atomized Al-Si alloy powders.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
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
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
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
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
If 2024 has taught me anything,it’s that digital is an irrefutable force for unity—a much-needed catalyst for global cooperation in an increasingly fragmented world.This truth has been on display all year long,somet...If 2024 has taught me anything,it’s that digital is an irrefutable force for unity—a much-needed catalyst for global cooperation in an increasingly fragmented world.This truth has been on display all year long,sometimes against the odds.And it’s evident in the adoption of the Pact for the Future and Global Digital Compact at the United Nations General Assembly,in the outcomes of the World Telecommunication Standardization Assembly(WTSA-24),and in the wide endorsement of the COP29 Declaration on Green Digital Action.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
Following the work of Li-Shi-Qing, we propose the definition of the relative volume function for an AH manifold. It is not a constant function in general and we study the regularity of this function. We use this funct...Following the work of Li-Shi-Qing, we propose the definition of the relative volume function for an AH manifold. It is not a constant function in general and we study the regularity of this function. We use this function to provide an accurate characterization of the height of the geodesic defining function for the AH manifold with a given boundary metric. Furthermore, it is shown that such functions are uniformly bounded from below at infinity and the bound only depends on the dimension. In the end, we apply this function to study the capacity of balls in AH manifolds and demonstrate that the “relative p—capacity function” coincides with the relative volume function under appropriate curvature conditions.展开更多
This paper presents a compact ultra-low-power phase-locked loop (PLL) based binary phase-shift keying(BPSK)demodulator. The loop-filter-less(LPF-less) PLL is proposed to make phase of PLL output carrier signal track t...This paper presents a compact ultra-low-power phase-locked loop (PLL) based binary phase-shift keying(BPSK)demodulator. The loop-filter-less(LPF-less) PLL is proposed to make phase of PLL output carrier signal track the phase of BPSK signal in real time. Thus, the maximum date rate can be significantly extended to the half of the carrier frequency(f_(carrier)) with a very compact size compared to prior PLL-based BPSK demodulators. Furthermore, eliminating all the static power in our LPF-less PLL, the energy efficiency is obviously improved. Fabricated in a 40-nm CMOS process, our prototype occupies 0.0012-mm^(2)core active area, and achieves the maximum data rate of 6.78 Mb/s (f_(carrier)/2) at f_(carrier)of 13.56 MHz. The power consumption and energy efficiency is 4.47 μW and 0.66 pJ/bit at 6.78-Mb/s data rate, respectively.展开更多
基金Project(JPPT-125-GJGG-14-016)supported by Military Supporting Projects of National Defense Science and Technology Industry Committee,China
文摘Effect of pre-annealing treatment temperature on compactibility of gas-atomized Al-27%Si alloy powders was investigated. Microstructure and hardness of the annealed powders were characterized. Pre-annealing results in decreasing Al matrix hardness, dissolving of needle-like eutectic Si phase, precipitation and growth of supersaturated Si atoms, and spheroidisation of primary Si phase. Compactibility of the alloy powders is gradually improved with increasing the annealing temperature to 400 ℃. However, it decreases when the temperature is above 400 ℃ owing to the existence of Si-Si phase clusters and the densely distributed Si particles. A maximum relative density of 96.1% is obtained after annealing at 400 ℃ for 4 h. In addition, the deviation of compactibility among the pre-annealed powders reaches a maximum at a pressure of 175 MPa. Therefore, a proper pre-annealing treatment can significantly enhance the cold compactibility of gas-atomized Al-Si alloy powders.
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.
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.
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”.
文摘If 2024 has taught me anything,it’s that digital is an irrefutable force for unity—a much-needed catalyst for global cooperation in an increasingly fragmented world.This truth has been on display all year long,sometimes against the odds.And it’s evident in the adoption of the Pact for the Future and Global Digital Compact at the United Nations General Assembly,in the outcomes of the World Telecommunication Standardization Assembly(WTSA-24),and in the wide endorsement of the COP29 Declaration on Green Digital Action.
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).
文摘Following the work of Li-Shi-Qing, we propose the definition of the relative volume function for an AH manifold. It is not a constant function in general and we study the regularity of this function. We use this function to provide an accurate characterization of the height of the geodesic defining function for the AH manifold with a given boundary metric. Furthermore, it is shown that such functions are uniformly bounded from below at infinity and the bound only depends on the dimension. In the end, we apply this function to study the capacity of balls in AH manifolds and demonstrate that the “relative p—capacity function” coincides with the relative volume function under appropriate curvature conditions.
基金supported by the National Natural Science Foundation of China under grant 62222409 and 62174153by Key Research Program of Frontier Sciences, CAS, under grant ZDBS-LY-JSC008。
文摘This paper presents a compact ultra-low-power phase-locked loop (PLL) based binary phase-shift keying(BPSK)demodulator. The loop-filter-less(LPF-less) PLL is proposed to make phase of PLL output carrier signal track the phase of BPSK signal in real time. Thus, the maximum date rate can be significantly extended to the half of the carrier frequency(f_(carrier)) with a very compact size compared to prior PLL-based BPSK demodulators. Furthermore, eliminating all the static power in our LPF-less PLL, the energy efficiency is obviously improved. Fabricated in a 40-nm CMOS process, our prototype occupies 0.0012-mm^(2)core active area, and achieves the maximum data rate of 6.78 Mb/s (f_(carrier)/2) at f_(carrier)of 13.56 MHz. The power consumption and energy efficiency is 4.47 μW and 0.66 pJ/bit at 6.78-Mb/s data rate, respectively.
