Using first-principles calculations, we study the tailoring of the electronic and magnetic properties of gallium sulfide nanoribbons（Ga2S2NRs） by mechanical strain. Hydrogen-passivated armchair-and zigzag-edged NRs...Using first-principles calculations, we study the tailoring of the electronic and magnetic properties of gallium sulfide nanoribbons（Ga2S2NRs） by mechanical strain. Hydrogen-passivated armchair-and zigzag-edged NRs（ANRs and ZNRs）with different widths are investigated. Significant effects in band gap and magnetic properties are found and analyzed. First,the band gaps and their nature of ANRs can be largely tailored by a strain. The band gaps can be markedly reduced, and show an indirect-direct（I-D） transition under a tensile strain. While under an increasing compressive strain, they undergo a series transitions of I-D-I-D. Five strain zones with distinct band structures and their boundaries are identified. In addition,the carrier effective masses of ANRs are also tunable by the strain, showing jumps at the boundaries. Second, the magnetic moments of（ferromagnetic） ZNRs show jumps under an increasing compressive strain due to spin density redistribution,but are unresponsive to tensile strains. The rich tunable properties by stain suggest potential applications of Ga2S2 NRs in nanoelectronics and optoelectronics.展开更多
With the high theoretical specific capacity and energy density,lithium-sulfur batteries(LSBs)have been intensively studied as promising candidates for energy storage devices.However,LSBs are largely hindered by inferi...With the high theoretical specific capacity and energy density,lithium-sulfur batteries(LSBs)have been intensively studied as promising candidates for energy storage devices.However,LSBs are largely hindered by inferior sulfur utilization and uncontrollable dendritic growth.Herein,a hierarchical functionalization strategy of stepwise catalytic-adsorption-conversion for sulfur species via the synergetic of the efficiently catalytic host cathode and light multifunctional interlayer has been proposed to concurrently address the issues arising on the dual sides of the LSBs.The multi-layer SnS_(2) micro-flowers embedded into the natural three-dimensional(3D)interconnected carbonized bacterial cellulose(CBC)nanofibers are fabricated as the sulfur host that provides numerous catalytic sites for the rapid catalytic conversion of sulfur species.Moreover,the distinctive CBC-based SnO_(2)-SnS_(2) heterostructure network accompanied high conductive carbon nanofibers as the multifunctional interlayer promotes the rapid anchoringdiffusion-conversion of lithium polysulfides,Li^(+)flux redistribution,and uniform Li deposition.LSBs equipped with our strategy exhibit a high reversible capacity of 1361.5 m A h g^(-1)at 0.2 C and superior cycling stability with an ultra-low capacity fading of 0.031%per cycle in 1000 cycles at 1.5 C and 0.046%at 3 C.A favorable specific capacity of 859.5 m A h g^(-1)at 0.3 C is achieved with a high sulfur mass loading of 5.2 mg cm^(-2),highlighting the potential of practical application.The rational design in this work can provide a feasible solution for high-performance LSBs and promote the development of advanced energy storage devices.展开更多
Image segmentation of sea-land remote sensing images is of great importance for downstream applications including shoreline extraction,the monitoring of near-shore marine environment,and near-shore target recognition....Image segmentation of sea-land remote sensing images is of great importance for downstream applications including shoreline extraction,the monitoring of near-shore marine environment,and near-shore target recognition.To mitigate large number of parameters and improve the segmentation accuracy,we propose a new Squeeze-Depth-Wise UNet(SDW-UNet)deep learning model for sea-land remote sensing image segmentation.The proposed SDW-UNet model leverages the squeeze-excitation and depth-wise separable convolution to construct new convolution modules,which enhance the model capacity in combining multiple channels and reduces the model parameters.We further explore the effect of position-encoded information in NLP(Natural Language Processing)domain on sea-land segmentation task.We have conducted extensive experiments to compare the proposed network with the mainstream segmentation network in terms of accuracy,the number of parameters and the time cost for prediction.The test results on remote sensing data sets of Guam,Okinawa,Taiwan China,San Diego,and Diego Garcia demonstrate the effectiveness of SDW-UNet in recognizing different types of sea-land areas with a smaller number of parameters,reduces prediction time cost and improves performance over other mainstream segmentation models.We also show that the position encoding can further improve the accuracy of model segmentation.展开更多
The dissemination of information across various locations is an ubiquitous occurrence,however,prevalent methodologies for multi-source identification frequently overlook the fact that sources may initiate disseminatio...The dissemination of information across various locations is an ubiquitous occurrence,however,prevalent methodologies for multi-source identification frequently overlook the fact that sources may initiate dissemination at distinct initial moments.Although there are many research results of multi-source identification,the challenge of locating sources with varying initiation times using a limited subset of observational nodes remains unresolved.In this study,we provide the backward spread tree theorem and source centrality theorem,and develop a backward spread centrality algorithm to identify all the information sources that trigger the spread at different start times.The proposed algorithm does not require prior knowledge of the number of sources,however,it can estimate both the initial spread moment and the spread duration.The core concept of this algorithm involves inferring suspected sources through source centrality theorem and locating the source from the suspected sources with linear programming.Extensive experiments from synthetic and real network simulation corroborate the superiority of our method in terms of both efficacy and efficiency.Furthermore,we find that our method maintains robustness irrespective of the number of sources and the average degree of network.Compared with classical and state-of-the art source identification methods,our method generally improves the AUROC value by 0.1 to 0.2.展开更多
The development of the fifth-generation(5G)mobile communication systems has entered the commercialization stage.5G has a high data rate,low latency,and high reliability that can meet the basic demands of most industri...The development of the fifth-generation(5G)mobile communication systems has entered the commercialization stage.5G has a high data rate,low latency,and high reliability that can meet the basic demands of most industries and daily life,such as the Internet of Things(IoT),intelligent transportation systems,positioning,and navigation.The continuous progress and development of society have aroused wide concern.Positioning accuracy is the core demand for the applications,especially in complex environments such as airports,warehouses,supermarkets,and basements.However,many factors also affect the accuracy of positioning in those environments,for example,multipath effects,non-line-of-sight,and clock synchronization errors.This paper provides a comprehensive review of the existing works about positioning for the future wireless network and discusses its key techniques and algorithms,as well as the current development and future directions.We first outline the current traditional positioning technologies and algorithms,which are discussed and analyzed with the relevant literature.In addition,we also discuss application scenarios for wireless localization.By comparing different positioning systems,the challenges and future development directions of existing wireless positioning systems are prospected.展开更多
Ab initio density functional theory calculations are carried out to predict the electronic properties and relative stability of gallium sulfide nanoribbons(Ga2S2-NRs) with either zigzag- or armchair-terminated edges. ...Ab initio density functional theory calculations are carried out to predict the electronic properties and relative stability of gallium sulfide nanoribbons(Ga2S2-NRs) with either zigzag- or armchair-terminated edges. It is found that the electronic properties of the nanoribbons are very sensitive to the edge structure. The zigzag nanoribbons(Ga2S2-ZNRs)are ferromagnetic(FM) metallic with spin-polarized edge states regardless of the H-passivation, whereas the bare armchair ones(Ga2S2-ANRs) are semiconducting with an indirect band gap. This band gap exhibits an oscillation behavior as the width increases and finally converges to a constant value. Similar behavior is also found in H-saturated Ga2S2-ANRs,although the band gap converges to a larger value. The relative stabilities of the bare ANRs and ZNRs are investigated by calculating their binding energies. It is found that for a similar width the ANRs are more stable than the ZNRs, and both are more stable than some Ga2S2nanoclusters with stable configurations.展开更多
The systematic trends of electrionic structure and optical properties of rutile （P42/mnm） RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory （DFT） method ...The systematic trends of electrionic structure and optical properties of rutile （P42/mnm） RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory （DFT） method within the generalised gradient approximation （GGA） for the exchange-correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on elec- tronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant （~1 and z2, respectively） and the refractive index （n）; and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.展开更多
This paper calculates the elastic, thermodynamic and electronic properties of pyrite （Pa^-3） RuO2 by the plane-wave pseudopotential density functional theory （DFT） method. The lattice parameters, normalized elasti...This paper calculates the elastic, thermodynamic and electronic properties of pyrite （Pa^-3） RuO2 by the plane-wave pseudopotential density functional theory （DFT） method. The lattice parameters, normalized elastic constants, Cauchy pressure, brittle-ductile relations, heat capacity and Debye temperature are successfully obtained. The Murnaghan equation of state shows that pyrite RuO2 is a potential superhard material. Internal coordinate parameter increases with pressure, which disagrees with experimental data. An analysis based on electronic structure and the pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonding. A study of the elastic properties indicates that the pyrite phase is isotropic under usual conditions. The relationship between brittleness and ductility shows that pyrite RuO2 behaves in a ductile matter at zero pressure and the degree of ductility increases with pressure.展开更多
The traditional orthogonal frequency divi-sion multiplexing(OFDM)transmitter is implemented by inverse fast Fourier transform(IFFT),up-sampling and low pass shaping filter(LPSF),which occupy a large number of hardware...The traditional orthogonal frequency divi-sion multiplexing(OFDM)transmitter is implemented by inverse fast Fourier transform(IFFT),up-sampling and low pass shaping filter(LPSF),which occupy a large number of hardware resources and have long la-tency.To further meet the 5G and future 6G commu-nication requirements,this paper proposes a novel di-rect digital synthesis(DDS)based OFDM transmitter structure that can replace these modules.Due to the strong parallelism of the system structure,it is very suitable for implementation on field programable gate array(FPGA)platform.After making two special sim-plifications to the primary structure,the refined struc-ture becomes very simple compared with the tradi-tional structures.Most attractively,the proposed struc-ture has the following three advantages that i)the data transformation from frequency domain to time domain has zero latency,ii)the transformation length does not need to be an integer power of 2 and iii)the struc-ture does not even need to use any multiplier,thus leading to low implementation complexity and high speed.Comparative experiments are carried out on Intel FPGA platform which show that our DDS based structure can save more than half of the resources com-pared with the traditional structures and can provide the same bit error rate(BER)performance under the condition without using any LPSF.展开更多
By using the B3P86/aug-cc-pvtz method, the accurate equilibrium geometry of the AlSO （Cs, X2AH） molecule has been calculated and compared with available theoreticM values. The obtained results show that the AlSO mol...By using the B3P86/aug-cc-pvtz method, the accurate equilibrium geometry of the AlSO （Cs, X2AH） molecule has been calculated and compared with available theoreticM values. The obtained results show that the AlSO molecule has a most stable structure with bond lengths of ROA1= 0.1864 nm, ROS=0.1623 nm, RAIS=0.2450 nm, together with a dissociation energy of 13.88 eV. The possible electronic states and their reasonable dissociation limits for the ground state of the AlSO molecule were determined based on the principle of atomic and molecular reaction statics. The analytic potential energy function of the AlSO molecule was derived by the many-body expansion theory and the contour lines were constructed for the first time, which show the internal information of the AlSO molecule, including the equilibrium structure and stable point. The analysis demonstrates that the obtained potential energy function of AlSO is reaSonable and successful and the present investigations provide important insights for further study on molecular reaction dynamics.展开更多
Aluminum-doped ZnO(AZO) thin films with thin film metallic glass of Zr(50)Cu(50) as buffer are prepared on glass substrates by the pulsed laser deposition. The influence of buffer thickness and substrate temperature o...Aluminum-doped ZnO(AZO) thin films with thin film metallic glass of Zr(50)Cu(50) as buffer are prepared on glass substrates by the pulsed laser deposition. The influence of buffer thickness and substrate temperature on structural, optical, and electrical properties of AZO thin film are investigated. Increasing the thickness of buffer layer and substrate temperature can both promote the transformation of AZO from amorphous to crystalline structure, while they show(100)and(002) unique preferential orientations, respectively. After inserting Zr(50)Cu(50) layer between the glass substrate and AZO film, the sheet resistance and visible transmittance decrease, but the infrared transmittance increases. With substrate temperature increasing from 25℃ to 520℃, the sheet resistance of AZO(100 nm)/Zr(50)Cu(50)(4 nm) film first increases and then decreases, and the infrared transmittance is improved. The AZO(100 nm)/Zr(50)Cu(50)(4 nm) film deposited at a substrate temperature of 360℃ exhibits a low sheet resistance of 26.7 ?/, high transmittance of 82.1% in the visible light region, 81.6% in near-infrared region, and low surface roughness of 0.85 nm, which are useful properties for their potential applications in tandem solar cell and infrared technology.展开更多
In citric acid-based carbon dots,molecular fluorophore contributes greatly to the fluorescence emission.In this paper,the nitrogen and sulfur co-doped carbon dots(N,S-CDs)were prepared,and an independent sulfur source...In citric acid-based carbon dots,molecular fluorophore contributes greatly to the fluorescence emission.In this paper,the nitrogen and sulfur co-doped carbon dots(N,S-CDs)were prepared,and an independent sulfur source is selected to achieve the doping controllability.The influence of sulfur doping on the molecular fluorophore was systematically studied.The introduction of sulfur atoms may promote the formation of molecular fluorophore due to the increased nitrogen content in CDs.The addition surface states containing sulfur were produced,and S element exists as-SO_(3),and-SO_(4)groups.Appreciate ratio of nitrogen and sulfur sources can improve the fluorescence emission.The photoluminescence quantum yields(PLQY)is increased from 56.4%of the single N-doping CDs to 63.4%of double-doping CDs,which ascribes to the synergistic effect of molecular fluorophores and surface states.The sensitivity of fluorescence to pH response and various metal ions was also explored.展开更多
This paper derives the force of the electromagnetic radiation on left-handed materials （LHMs） by a direct application of the Lorentz law of classical electrodynamics. The expressions of radiation force are given for...This paper derives the force of the electromagnetic radiation on left-handed materials （LHMs） by a direct application of the Lorentz law of classical electrodynamics. The expressions of radiation force are given for TE-polarised and TM-polarised fields. The numerical results demonstrate that electromagnetic waves exert an inverse lateral radiation force on each edge of the beams, that is, the lateral pressure is expansive for TE-polarised beams and compressive for TM-polarised beams. The investigation of the radiation force will provide insights into the fundamental properties of LHMs and will provide to better understanding of the interaction of light with LHMs.展开更多
The morphologies of intermetallic phases(IMCs)during directional solidification of the Sn-Cu(L+Cu_(3)Sn→Cu_(6)Sn_(5))and Sn-Co(L+CoSn→CoSn_(2))peritectic systems were analyzed.The primary Cu_(3)Sn and peritectic Cu_...The morphologies of intermetallic phases(IMCs)during directional solidification of the Sn-Cu(L+Cu_(3)Sn→Cu_(6)Sn_(5))and Sn-Co(L+CoSn→CoSn_(2))peritectic systems were analyzed.The primary Cu_(3)Sn and peritectic Cu_(6)Sn_(5)phases in Sn-Cu alloy are IMCs whose solubility ranges are narrow,while both the primary CoSn and peritectic CoSn_(2)phases in Sn-Co alloy are IMCs whose solubility ranges are nil in equilibrium condition.The experimental results before acid corrosion shows that the dendritic morphology of both the Cu_(6)Sn_(5)and CoSn_(2)phases can be observed.The investigation on the local dendritic morphology after deep acid corrosion shows that these dendrites are composed of small sub-structures with faceted feature.Faceted growth of the primary Cu_(3)Sn and CoSn phases is also confirmed,and a faceted to non-faceted transition in their morphologies is observed with increasing growth velocities.Further analysis shows that the dendritic morphology is formed in the solidified phases whose solubility range is larger during peritectic solidification.展开更多
Differential polarization imaging has been widely used to selectively probe the target embedded in turbid medium.A thorough understanding of image quality involved in differential polarization imaging is essential for...Differential polarization imaging has been widely used to selectively probe the target embedded in turbid medium.A thorough understanding of image quality involved in differential polarization imaging is essential for practical use.Using polarized light Monte Carlo simulations,it has been investigated how the state of polarization of incident light and the optical properties of scattering medium affect the image contrast.The contrast for linear polarization is similar to that for circular polarization in the isotropic medium comprising small-particles.The image quality is more pronounced for circular polarization in the isotropic medium containing large-particles and the birefringent medium.Furthermore,differential polarization imaging provides better image quality for the birefringent medium compared with isotropic medium.The effect of particle-size and birefringence on the polarization characteristics of target light and backscattered light is investigated.With the help of numerical results,the polarization characteristics of target light and backscattered light,the image quality is well explained in the turbid medium mentioned above.展开更多
In this article,structural probabilistic and non-probabilistic reliability have been evaluated and compared under big data condition.Firstly,the big data is collected via structural monitoring and analysis.Big data is...In this article,structural probabilistic and non-probabilistic reliability have been evaluated and compared under big data condition.Firstly,the big data is collected via structural monitoring and analysis.Big data is classified into different types according to the regularities of the distribution of data.The different stresses which have been subjected by the structure are used in this paper.Secondly,the structural interval reliability and probabilistic pre-diction models are established by using the stress-strength interference theory under big data of random loads after the stresses and structural strength are comprehensively considered.Structural reliability is computed by using various stress types,and the minimum reliability is determined as structural reliability.Finally,the advan-tage and disadvantage of the interval reliability method and probability reliability method are shown by using three examples.It has been shown that the proposed methods are feasible and effective.展开更多
Taking into account the effects of shadowing and jet quenching, the large transverse momentum distribution of K＋, π＋ and K＋/π＋ ratios at s = 200 GeV originating from resolved photoproduction processes is calcula...Taking into account the effects of shadowing and jet quenching, the large transverse momentum distribution of K＋, π＋ and K＋/π＋ ratios at s = 200 GeV originating from resolved photoproduction processes is calculated based on perturbative quantum chromodynamics. It is found that the contribution of K＋ and π＋ produced by photoproduction processes is evident. The K＋ /π＋ ratios in Au-Au collisions show an obvious enhancement compared with p p collisions. The numerical results indicate that the photoproduetion processes are good modification for kaon and pion production.展开更多
Converting solar energy into electric power or hydrogen fuel is a promising means to obtain renewable green energy.Here, we design a two-dimensional blue phosphorene(BlueP)/MoSi2N4van der Waals heterostructure(vdWH) a...Converting solar energy into electric power or hydrogen fuel is a promising means to obtain renewable green energy.Here, we design a two-dimensional blue phosphorene(BlueP)/MoSi2N4van der Waals heterostructure(vdWH) and investigate its potential application in photocatalysis and photovoltaics using first-principles calculations. We find that the BlueP/MoSi2N4vdWH possesses type-Ⅱ band structure with a large build-in electric field, thus endowing it with a potential ability to separate photogenerated electron–hole pairs. The calculated band-edge positions show that the heterostructure is a very promising water-splitting photocatalyst. Its solar-to-hydrogen efficiency(ηSTH) can reach up to 15.8%, which is quite promising for commercial applications. Furthermore, the BlueP/MoSi2N4vdWH shows remarkably light absorption capacity and distinguished maximum power conversion efficiency(ηPCE) up to 10.61%. Remarkably, its ηPCEcan be further enhanced by the external strain: the ηPCEof 21.20% can be obtained under a 4% tensile strain. Finally, we determine that adjusting the number of the BlueP sublayer is another effective method to modulate the band gaps and band alignments of the heterostructures. These theoretical findings indicate that BlueP/MoSi2N4vd WH is a promising candidate for photocatalyst and photovoltaic device.展开更多
Aqueous zinc ion batteries(AZIBs) have received great attention because of their non-toxicity,high safety,low cost,high abundance,and high specific power.However,their specific capacity is still low compared with lith...Aqueous zinc ion batteries(AZIBs) have received great attention because of their non-toxicity,high safety,low cost,high abundance,and high specific power.However,their specific capacity is still low compared with lithium ion battery,and current academic research interesting has been focused on developing new cathode materials with high specific capacity.In this study,a Mn/V hybrid polymer framework is designed by a simple self-polymerization scheme.During subsequent calcination,ultrafine VN quantum dots and MnO nanoparticles are generated in situ and stably encapsulated inside N-doped carbon(NC) shells to obtain a novel hybrid cathode NC@VN/MnO for AZIBs.According to the density functional theory(DFT) calculation,the hybrids of MnO and VN can generate both interfacial effects and built-in electric fields that significantly accelerate ion and electron transport by tuning the intrinsic electronic structure,thus enhancing electrochemical performance.A synergistic strategy of composition and structural design allows the rechargeable AZIBs to achieve low-cost and excellent long-cycle performance based on a relay type collaboration at different cycling stages.Consequently,the NC@VN/MnO cathode has output a capacity of 108.3 mA h g^(-1)after 12,000 cycles at 10 A g^(-1).These results clearly and fully demonstrate the advantages of the hybrid cathode NC@VN/MnO.展开更多
In the process of hot-dip Zn-Al-Mg alloy coating,the plating solution dissipates heat in the direction perpendicular to the steel plate,which is considered to be a process of directional solidification.To understand t...In the process of hot-dip Zn-Al-Mg alloy coating,the plating solution dissipates heat in the direction perpendicular to the steel plate,which is considered to be a process of directional solidification.To understand the relationship between microstructure and cooling rate of Zn-Al-Mg alloys,both the phase constitution and microstructure characteristic length scales of Zn-9.5Al-3Mg-0.01Ce(wt.%)alloy were investigated by the directional solidification experiments at different growth velocities(V=40,80,160,250μm·s^(-1)).The experimental results show that the microstructure of directionally solidified Zn-9.5Al-3Mg-0.01Ce alloy is composed of primary Al dendrites and(Zn-Al-Mg2Zn11)ternary eutectics at the growth velocities ranging from 40 to 250μm·s^(-1).The primary Al dendrites are aligned regularly along the growth direction,accompanied with obvious secondary dendrites.The relationship between the microstructure length scale and the thermal parameters of solidification is obtained:λ1=374.66V-0.383,andλ2=167.5V-0.563(λ1is the primary dendrite arm spacing,andλ2 is the secondary dendrit arm spacing).In addition,through the interface response function(IRF)and the nucleation and constitutional undercooling(NCU),the phase selection of Zn-9.5Al-3Mg-0.01Ce is obtained:(Zn+Al+Mg2Zn11)ternary eutectics in the Zn-9.5Al-3Mg-0.01Ce alloy will be replaced by ternary eutectics(Zn+Al+MgZn2)when the growth rate is lower than 7.53μm·s^(-1).展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174220 and 11374226)the Key Scientific Research Project of the Henan Institutions of Higher Learning,China(Grant No.16A140009)+2 种基金the Program for Innovative Research Team of Henan Polytechnic University,China(Grant Nos.T2015-3 and T2016-2)the Doctoral Foundation of Henan Polytechnic University,China(Grant No.B2015-46)the High-performance Grid Computing Platform of Henan Polytechnic University,China
文摘Using first-principles calculations, we study the tailoring of the electronic and magnetic properties of gallium sulfide nanoribbons（Ga2S2NRs） by mechanical strain. Hydrogen-passivated armchair-and zigzag-edged NRs（ANRs and ZNRs）with different widths are investigated. Significant effects in band gap and magnetic properties are found and analyzed. First,the band gaps and their nature of ANRs can be largely tailored by a strain. The band gaps can be markedly reduced, and show an indirect-direct（I-D） transition under a tensile strain. While under an increasing compressive strain, they undergo a series transitions of I-D-I-D. Five strain zones with distinct band structures and their boundaries are identified. In addition,the carrier effective masses of ANRs are also tunable by the strain, showing jumps at the boundaries. Second, the magnetic moments of（ferromagnetic） ZNRs show jumps under an increasing compressive strain due to spin density redistribution,but are unresponsive to tensile strains. The rich tunable properties by stain suggest potential applications of Ga2S2 NRs in nanoelectronics and optoelectronics.
基金financially supported by the National Natural Science Foundation of China (52073212,52272303)。
文摘With the high theoretical specific capacity and energy density,lithium-sulfur batteries(LSBs)have been intensively studied as promising candidates for energy storage devices.However,LSBs are largely hindered by inferior sulfur utilization and uncontrollable dendritic growth.Herein,a hierarchical functionalization strategy of stepwise catalytic-adsorption-conversion for sulfur species via the synergetic of the efficiently catalytic host cathode and light multifunctional interlayer has been proposed to concurrently address the issues arising on the dual sides of the LSBs.The multi-layer SnS_(2) micro-flowers embedded into the natural three-dimensional(3D)interconnected carbonized bacterial cellulose(CBC)nanofibers are fabricated as the sulfur host that provides numerous catalytic sites for the rapid catalytic conversion of sulfur species.Moreover,the distinctive CBC-based SnO_(2)-SnS_(2) heterostructure network accompanied high conductive carbon nanofibers as the multifunctional interlayer promotes the rapid anchoringdiffusion-conversion of lithium polysulfides,Li^(+)flux redistribution,and uniform Li deposition.LSBs equipped with our strategy exhibit a high reversible capacity of 1361.5 m A h g^(-1)at 0.2 C and superior cycling stability with an ultra-low capacity fading of 0.031%per cycle in 1000 cycles at 1.5 C and 0.046%at 3 C.A favorable specific capacity of 859.5 m A h g^(-1)at 0.3 C is achieved with a high sulfur mass loading of 5.2 mg cm^(-2),highlighting the potential of practical application.The rational design in this work can provide a feasible solution for high-performance LSBs and promote the development of advanced energy storage devices.
基金This paper is supported by the following funds:The National Key Research and Development Program of China(2018YFF01010100)The Beijing Natural Science Foundation(4212001)+1 种基金Basic Research Program of Qinghai Province under Grants No.2021-ZJ-704Advanced information network Beijing laboratory(PXM2019_014204_500029).
文摘Image segmentation of sea-land remote sensing images is of great importance for downstream applications including shoreline extraction,the monitoring of near-shore marine environment,and near-shore target recognition.To mitigate large number of parameters and improve the segmentation accuracy,we propose a new Squeeze-Depth-Wise UNet(SDW-UNet)deep learning model for sea-land remote sensing image segmentation.The proposed SDW-UNet model leverages the squeeze-excitation and depth-wise separable convolution to construct new convolution modules,which enhance the model capacity in combining multiple channels and reduces the model parameters.We further explore the effect of position-encoded information in NLP(Natural Language Processing)domain on sea-land segmentation task.We have conducted extensive experiments to compare the proposed network with the mainstream segmentation network in terms of accuracy,the number of parameters and the time cost for prediction.The test results on remote sensing data sets of Guam,Okinawa,Taiwan China,San Diego,and Diego Garcia demonstrate the effectiveness of SDW-UNet in recognizing different types of sea-land areas with a smaller number of parameters,reduces prediction time cost and improves performance over other mainstream segmentation models.We also show that the position encoding can further improve the accuracy of model segmentation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62103375,62006106,61877055,and 62171413)the Philosophy and Social Science Planning Project of Zhejinag Province,China(Grant No.22NDJC009Z)+1 种基金the Education Ministry Humanities and Social Science Foundation of China(Grant No.19YJCZH056)the Natural Science Foundation of Zhejiang Province,China(Grant Nos.LY23F030003,LY22F030006,and LQ21F020005).
文摘The dissemination of information across various locations is an ubiquitous occurrence,however,prevalent methodologies for multi-source identification frequently overlook the fact that sources may initiate dissemination at distinct initial moments.Although there are many research results of multi-source identification,the challenge of locating sources with varying initiation times using a limited subset of observational nodes remains unresolved.In this study,we provide the backward spread tree theorem and source centrality theorem,and develop a backward spread centrality algorithm to identify all the information sources that trigger the spread at different start times.The proposed algorithm does not require prior knowledge of the number of sources,however,it can estimate both the initial spread moment and the spread duration.The core concept of this algorithm involves inferring suspected sources through source centrality theorem and locating the source from the suspected sources with linear programming.Extensive experiments from synthetic and real network simulation corroborate the superiority of our method in terms of both efficacy and efficiency.Furthermore,we find that our method maintains robustness irrespective of the number of sources and the average degree of network.Compared with classical and state-of-the art source identification methods,our method generally improves the AUROC value by 0.1 to 0.2.
基金supported by the Key Project of Guizhou Science and Technology Support Program,Guizhou Key Science and Support[2021]-001supported by the Key Laboratory of Cognitive Radio and Information Processing,Ministry of Education(Guilin University of Electronic Technology)(CRKL220203)+2 种基金Key Laboratory of Middle Atmosphere and Global Environment Observation(LAGEO)Institute of Atmospheric Physics,Chinese Academy of Sciences(LAGEO-2022-02)Henan Province Key R&D and Promotion Special Project(No.212102210166)“Double First-Class”Discipline Creation Project of Surveying Science and Technology(GCCRC202306).
文摘The development of the fifth-generation(5G)mobile communication systems has entered the commercialization stage.5G has a high data rate,low latency,and high reliability that can meet the basic demands of most industries and daily life,such as the Internet of Things(IoT),intelligent transportation systems,positioning,and navigation.The continuous progress and development of society have aroused wide concern.Positioning accuracy is the core demand for the applications,especially in complex environments such as airports,warehouses,supermarkets,and basements.However,many factors also affect the accuracy of positioning in those environments,for example,multipath effects,non-line-of-sight,and clock synchronization errors.This paper provides a comprehensive review of the existing works about positioning for the future wireless network and discusses its key techniques and algorithms,as well as the current development and future directions.We first outline the current traditional positioning technologies and algorithms,which are discussed and analyzed with the relevant literature.In addition,we also discuss application scenarios for wireless localization.By comparing different positioning systems,the challenges and future development directions of existing wireless positioning systems are prospected.
基金supported by the National Natural Science Foundation of China(Grant Nos.11174220 and 11374226)the Key Scientific Research Project of the Henan Institutions of Higher Learning(Grant No.16A140009)+1 种基金the Program for Innovative Research Team of Henan Polytechnic University(Grant Nos.T2015-3 and T2016-2)the Doctoral Foundation of Henan Polytechnic University(Grant No.B2015-46)
文摘Ab initio density functional theory calculations are carried out to predict the electronic properties and relative stability of gallium sulfide nanoribbons(Ga2S2-NRs) with either zigzag- or armchair-terminated edges. It is found that the electronic properties of the nanoribbons are very sensitive to the edge structure. The zigzag nanoribbons(Ga2S2-ZNRs)are ferromagnetic(FM) metallic with spin-polarized edge states regardless of the H-passivation, whereas the bare armchair ones(Ga2S2-ANRs) are semiconducting with an indirect band gap. This band gap exhibits an oscillation behavior as the width increases and finally converges to a constant value. Similar behavior is also found in H-saturated Ga2S2-ANRs,although the band gap converges to a larger value. The relative stabilities of the bare ANRs and ZNRs are investigated by calculating their binding energies. It is found that for a similar width the ANRs are more stable than the ZNRs, and both are more stable than some Ga2S2nanoclusters with stable configurations.
基金supported by the China Scholarship Council (CSC) and the National Natural Science Foundation of China (Grant Nos. 10676025 and 10574096)the Science-Technology Foundation for Young Scientist of Sichuan Province,China (Grant No. 09ZQ026-049)
文摘The systematic trends of electrionic structure and optical properties of rutile （P42/mnm） RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory （DFT） method within the generalised gradient approximation （GGA） for the exchange-correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on elec- tronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant （~1 and z2, respectively） and the refractive index （n）; and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.
基金Project supported by the China Scholarship Council (CSC)the National Natural Science Foundation of China (Grant Nos 10676025 and 10574096)
文摘This paper calculates the elastic, thermodynamic and electronic properties of pyrite （Pa^-3） RuO2 by the plane-wave pseudopotential density functional theory （DFT） method. The lattice parameters, normalized elastic constants, Cauchy pressure, brittle-ductile relations, heat capacity and Debye temperature are successfully obtained. The Murnaghan equation of state shows that pyrite RuO2 is a potential superhard material. Internal coordinate parameter increases with pressure, which disagrees with experimental data. An analysis based on electronic structure and the pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonding. A study of the elastic properties indicates that the pyrite phase is isotropic under usual conditions. The relationship between brittleness and ductility shows that pyrite RuO2 behaves in a ductile matter at zero pressure and the degree of ductility increases with pressure.
基金the Natural Science Foun-dation of Hubei Province under Grant 2019CFB593National Natural Science Foundation of China un-der Grant 61961016Starting Fund for Doc-toral Research in Hubei Minzu University under Grant MY2018B018.
文摘The traditional orthogonal frequency divi-sion multiplexing(OFDM)transmitter is implemented by inverse fast Fourier transform(IFFT),up-sampling and low pass shaping filter(LPSF),which occupy a large number of hardware resources and have long la-tency.To further meet the 5G and future 6G commu-nication requirements,this paper proposes a novel di-rect digital synthesis(DDS)based OFDM transmitter structure that can replace these modules.Due to the strong parallelism of the system structure,it is very suitable for implementation on field programable gate array(FPGA)platform.After making two special sim-plifications to the primary structure,the refined struc-ture becomes very simple compared with the tradi-tional structures.Most attractively,the proposed struc-ture has the following three advantages that i)the data transformation from frequency domain to time domain has zero latency,ii)the transformation length does not need to be an integer power of 2 and iii)the struc-ture does not even need to use any multiplier,thus leading to low implementation complexity and high speed.Comparative experiments are carried out on Intel FPGA platform which show that our DDS based structure can save more than half of the resources com-pared with the traditional structures and can provide the same bit error rate(BER)performance under the condition without using any LPSF.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10974139 and 10964002)the Natural Science Foundation of Hainan Province,China(Grant No.110001)+3 种基金Guizhou Province,China(Grant No.[2009]2066)the Scientific Research Foundation by Zhejiang University of Technology,China(Grant No.109003729)the Science-Technology Foundation of Sichuan Province,China(Grant No.09ZQ026-049)the Fund of Aiding Elites' Research Condition of Guizhou Province, China(Grant No.TZJF-2008-42)
文摘By using the B3P86/aug-cc-pvtz method, the accurate equilibrium geometry of the AlSO （Cs, X2AH） molecule has been calculated and compared with available theoreticM values. The obtained results show that the AlSO molecule has a most stable structure with bond lengths of ROA1= 0.1864 nm, ROS=0.1623 nm, RAIS=0.2450 nm, together with a dissociation energy of 13.88 eV. The possible electronic states and their reasonable dissociation limits for the ground state of the AlSO molecule were determined based on the principle of atomic and molecular reaction statics. The analytic potential energy function of the AlSO molecule was derived by the many-body expansion theory and the contour lines were constructed for the first time, which show the internal information of the AlSO molecule, including the equilibrium structure and stable point. The analysis demonstrates that the obtained potential energy function of AlSO is reaSonable and successful and the present investigations provide important insights for further study on molecular reaction dynamics.
基金Project supported by the National Natural Science Foundation of China(Grant No.51571085)the Key Science and Technology Program of Henan Province,China(Grant No.19212210210)+1 种基金the Foundation of Henan Educational Committee,China(Grant No.13B430019)the Henan Postdoctoral Science Foundation,China。
文摘Aluminum-doped ZnO(AZO) thin films with thin film metallic glass of Zr(50)Cu(50) as buffer are prepared on glass substrates by the pulsed laser deposition. The influence of buffer thickness and substrate temperature on structural, optical, and electrical properties of AZO thin film are investigated. Increasing the thickness of buffer layer and substrate temperature can both promote the transformation of AZO from amorphous to crystalline structure, while they show(100)and(002) unique preferential orientations, respectively. After inserting Zr(50)Cu(50) layer between the glass substrate and AZO film, the sheet resistance and visible transmittance decrease, but the infrared transmittance increases. With substrate temperature increasing from 25℃ to 520℃, the sheet resistance of AZO(100 nm)/Zr(50)Cu(50)(4 nm) film first increases and then decreases, and the infrared transmittance is improved. The AZO(100 nm)/Zr(50)Cu(50)(4 nm) film deposited at a substrate temperature of 360℃ exhibits a low sheet resistance of 26.7 ?/, high transmittance of 82.1% in the visible light region, 81.6% in near-infrared region, and low surface roughness of 0.85 nm, which are useful properties for their potential applications in tandem solar cell and infrared technology.
基金Project supported by the National Natural Science Foundation of China(Grant No.51571085)the Key Scientific Research Projects of Colleges and Universities in Henan Province,China(Grant No.20A430015).
文摘In citric acid-based carbon dots,molecular fluorophore contributes greatly to the fluorescence emission.In this paper,the nitrogen and sulfur co-doped carbon dots(N,S-CDs)were prepared,and an independent sulfur source is selected to achieve the doping controllability.The influence of sulfur doping on the molecular fluorophore was systematically studied.The introduction of sulfur atoms may promote the formation of molecular fluorophore due to the increased nitrogen content in CDs.The addition surface states containing sulfur were produced,and S element exists as-SO_(3),and-SO_(4)groups.Appreciate ratio of nitrogen and sulfur sources can improve the fluorescence emission.The photoluminescence quantum yields(PLQY)is increased from 56.4%of the single N-doping CDs to 63.4%of double-doping CDs,which ascribes to the synergistic effect of molecular fluorophores and surface states.The sensitivity of fluorescence to pH response and various metal ions was also explored.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10974063)the Research Foundation of Wuhan National Laboratory (Grant No. P080008)the National "973" Project (Grant No. 2007CB310403)
文摘This paper derives the force of the electromagnetic radiation on left-handed materials （LHMs） by a direct application of the Lorentz law of classical electrodynamics. The expressions of radiation force are given for TE-polarised and TM-polarised fields. The numerical results demonstrate that electromagnetic waves exert an inverse lateral radiation force on each edge of the beams, that is, the lateral pressure is expansive for TE-polarised beams and compressive for TM-polarised beams. The investigation of the radiation force will provide insights into the fundamental properties of LHMs and will provide to better understanding of the interaction of light with LHMs.
基金the support of the National Natural Science Foundation of China (Grant No. 51871118)the Fast Support Project (Grant No. JZX7Y20210162400301)the fund of State Key Laboratory of Special Rare Metal Materials (Grant No. SKL2020K003)
文摘The morphologies of intermetallic phases(IMCs)during directional solidification of the Sn-Cu(L+Cu_(3)Sn→Cu_(6)Sn_(5))and Sn-Co(L+CoSn→CoSn_(2))peritectic systems were analyzed.The primary Cu_(3)Sn and peritectic Cu_(6)Sn_(5)phases in Sn-Cu alloy are IMCs whose solubility ranges are narrow,while both the primary CoSn and peritectic CoSn_(2)phases in Sn-Co alloy are IMCs whose solubility ranges are nil in equilibrium condition.The experimental results before acid corrosion shows that the dendritic morphology of both the Cu_(6)Sn_(5)and CoSn_(2)phases can be observed.The investigation on the local dendritic morphology after deep acid corrosion shows that these dendrites are composed of small sub-structures with faceted feature.Faceted growth of the primary Cu_(3)Sn and CoSn phases is also confirmed,and a faceted to non-faceted transition in their morphologies is observed with increasing growth velocities.Further analysis shows that the dendritic morphology is formed in the solidified phases whose solubility range is larger during peritectic solidification.
基金Doctoral Fund Project of Henan Polytechnic University(No.B2019-20)Key Scientific Research Projects of Henan Colleges and Universities(Nos.21A510004,20B430005)Natural Science Basic Research Plan in Shaanxi Province of China(No.2018JM6008)。
文摘Differential polarization imaging has been widely used to selectively probe the target embedded in turbid medium.A thorough understanding of image quality involved in differential polarization imaging is essential for practical use.Using polarized light Monte Carlo simulations,it has been investigated how the state of polarization of incident light and the optical properties of scattering medium affect the image contrast.The contrast for linear polarization is similar to that for circular polarization in the isotropic medium comprising small-particles.The image quality is more pronounced for circular polarization in the isotropic medium containing large-particles and the birefringent medium.Furthermore,differential polarization imaging provides better image quality for the birefringent medium compared with isotropic medium.The effect of particle-size and birefringence on the polarization characteristics of target light and backscattered light is investigated.With the help of numerical results,the polarization characteristics of target light and backscattered light,the image quality is well explained in the turbid medium mentioned above.
基金The work described in this paper was supported in part by the Foundation from the Science Foundation,Guizhou,China(Qian Kehe[2018]1055)Research Foundation for Talented Scholars in Ningxia Normal University.
文摘In this article,structural probabilistic and non-probabilistic reliability have been evaluated and compared under big data condition.Firstly,the big data is collected via structural monitoring and analysis.Big data is classified into different types according to the regularities of the distribution of data.The different stresses which have been subjected by the structure are used in this paper.Secondly,the structural interval reliability and probabilistic pre-diction models are established by using the stress-strength interference theory under big data of random loads after the stresses and structural strength are comprehensively considered.Structural reliability is computed by using various stress types,and the minimum reliability is determined as structural reliability.Finally,the advan-tage and disadvantage of the interval reliability method and probability reliability method are shown by using three examples.It has been shown that the proposed methods are feasible and effective.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11065010 and 11465021
文摘Taking into account the effects of shadowing and jet quenching, the large transverse momentum distribution of K＋, π＋ and K＋/π＋ ratios at s = 200 GeV originating from resolved photoproduction processes is calculated based on perturbative quantum chromodynamics. It is found that the contribution of K＋ and π＋ produced by photoproduction processes is evident. The K＋ /π＋ ratios in Au-Au collisions show an obvious enhancement compared with p p collisions. The numerical results indicate that the photoproduetion processes are good modification for kaon and pion production.
基金supported by the National Natural Science Foundation of China (Grant No. 11374226)the Fundamental Research Funds for the Universities of Henan Province of China (Grant No. NSFRF200331)+1 种基金the Foundation of Henan Educational Committee (Grant No. 20A140013)by the High-performance Grid Computing Platform of Henan Polytechnic University。
文摘Converting solar energy into electric power or hydrogen fuel is a promising means to obtain renewable green energy.Here, we design a two-dimensional blue phosphorene(BlueP)/MoSi2N4van der Waals heterostructure(vdWH) and investigate its potential application in photocatalysis and photovoltaics using first-principles calculations. We find that the BlueP/MoSi2N4vdWH possesses type-Ⅱ band structure with a large build-in electric field, thus endowing it with a potential ability to separate photogenerated electron–hole pairs. The calculated band-edge positions show that the heterostructure is a very promising water-splitting photocatalyst. Its solar-to-hydrogen efficiency(ηSTH) can reach up to 15.8%, which is quite promising for commercial applications. Furthermore, the BlueP/MoSi2N4vdWH shows remarkably light absorption capacity and distinguished maximum power conversion efficiency(ηPCE) up to 10.61%. Remarkably, its ηPCEcan be further enhanced by the external strain: the ηPCEof 21.20% can be obtained under a 4% tensile strain. Finally, we determine that adjusting the number of the BlueP sublayer is another effective method to modulate the band gaps and band alignments of the heterostructures. These theoretical findings indicate that BlueP/MoSi2N4vd WH is a promising candidate for photocatalyst and photovoltaic device.
基金supported by the National Natural Science Foundation of China,China (51772205, 52073212)。
文摘Aqueous zinc ion batteries(AZIBs) have received great attention because of their non-toxicity,high safety,low cost,high abundance,and high specific power.However,their specific capacity is still low compared with lithium ion battery,and current academic research interesting has been focused on developing new cathode materials with high specific capacity.In this study,a Mn/V hybrid polymer framework is designed by a simple self-polymerization scheme.During subsequent calcination,ultrafine VN quantum dots and MnO nanoparticles are generated in situ and stably encapsulated inside N-doped carbon(NC) shells to obtain a novel hybrid cathode NC@VN/MnO for AZIBs.According to the density functional theory(DFT) calculation,the hybrids of MnO and VN can generate both interfacial effects and built-in electric fields that significantly accelerate ion and electron transport by tuning the intrinsic electronic structure,thus enhancing electrochemical performance.A synergistic strategy of composition and structural design allows the rechargeable AZIBs to achieve low-cost and excellent long-cycle performance based on a relay type collaboration at different cycling stages.Consequently,the NC@VN/MnO cathode has output a capacity of 108.3 mA h g^(-1)after 12,000 cycles at 10 A g^(-1).These results clearly and fully demonstrate the advantages of the hybrid cathode NC@VN/MnO.
基金funded by the Key Science and Technology Projects of Gansu Province(Grant No.22ZD6GB019)the fund of the State Key Laboratory of Solidification Processing in NPU(Grant No.SKLSP202204)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2022-ey15)。
文摘In the process of hot-dip Zn-Al-Mg alloy coating,the plating solution dissipates heat in the direction perpendicular to the steel plate,which is considered to be a process of directional solidification.To understand the relationship between microstructure and cooling rate of Zn-Al-Mg alloys,both the phase constitution and microstructure characteristic length scales of Zn-9.5Al-3Mg-0.01Ce(wt.%)alloy were investigated by the directional solidification experiments at different growth velocities(V=40,80,160,250μm·s^(-1)).The experimental results show that the microstructure of directionally solidified Zn-9.5Al-3Mg-0.01Ce alloy is composed of primary Al dendrites and(Zn-Al-Mg2Zn11)ternary eutectics at the growth velocities ranging from 40 to 250μm·s^(-1).The primary Al dendrites are aligned regularly along the growth direction,accompanied with obvious secondary dendrites.The relationship between the microstructure length scale and the thermal parameters of solidification is obtained:λ1=374.66V-0.383,andλ2=167.5V-0.563(λ1is the primary dendrite arm spacing,andλ2 is the secondary dendrit arm spacing).In addition,through the interface response function(IRF)and the nucleation and constitutional undercooling(NCU),the phase selection of Zn-9.5Al-3Mg-0.01Ce is obtained:(Zn+Al+Mg2Zn11)ternary eutectics in the Zn-9.5Al-3Mg-0.01Ce alloy will be replaced by ternary eutectics(Zn+Al+MgZn2)when the growth rate is lower than 7.53μm·s^(-1).
