The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and ...The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and fluid mobility due to the influences of the northeast and northwest dual provenance systems.This study performed multiple experimental analyses on nine samples from the area to determine the petrological and petrophysical properties,as well as the PTS characteristics of reservoirs in different provenance-controlled regions.On this basis,the pore-throat size distribution(PSD)obtained from high-pressure mercury injection(HPMI)was utilized to convert the NMR movable fluid T2spectrum,allowing for quantitative characterization of the full PSD and the occurrence characteristics of movable fluids.A systematic analysis was conducted on the primary controlling factors affecting fluid mobility in the reservoir.The results indicated that the lithology in the eastern and western regions is lithic arkose.The eastern sandstones,being farther from the provenance,exhibit higher contents of feldspar and lithic fragments,along with the development of more dissolution pores.The reservoir possesses good petrophysical properties,low displacement pressure,and high pore-throat connectivity and homogeneity,indicating strong fluid mobility.In contrast,the western sandstones,being nearer to the provenance,exhibit poor grain sorting,high contents of lithic fragments,strong compaction and cementation effects,resulting in poor petrophysical properties,and strong pore-throat heterogeneity,revealing weak fluid mobility.The range of full PSD in the eastern reservoir is wider than that in the western reservoir,with relatively well-developed macropores.The macropores are the primary space for occurrence of movable fluids,and controls the fluid mobility of the reservoir.The effective porosity of movable fluids(EPMF)quantitatively represents the pore space occupied by movable fluids within the reservoir and correlates well with porosity,permeability,and PTS parameters,making it a valuable parameter for evaluating fluid mobility.Under the multi-provenance system,the eastern and western reservoirs underwent different sedimentation and diagenesis processes,resulting in differential distribution of reservoir mineral components and pore types,which in turn affects the PTS heterogeneity and reservoir quality.The composition and content of reservoir minerals are intrinsic factors influencing fluid mobility,while the microscopic PTS is the primary factor controlling it.Low clay mineral content,welldeveloped macropores,and weak pore-throat heterogeneity all contribute to the storage and seepage of reservoir fluids.展开更多
The development of sustainable electrode materials for energy storage systems has become very important and porous carbons derived from biomass have become an important candidate because of their tunable pore structur...The development of sustainable electrode materials for energy storage systems has become very important and porous carbons derived from biomass have become an important candidate because of their tunable pore structure,environmental friendliness,and cost-effectiveness.Recent advances in controlling the pore structure of these carbons and its relationship between to is energy storage performance are discussed,emphasizing the critical role of a balanced distribution of micropores,mesopores and macropores in determining electrochemical behavior.Particular attention is given to how the intrinsic components of biomass precursors(lignin,cellulose,and hemicellulose)influence pore formation during carbonization.Carbonization and activation strategies to precisely control the pore structure are introduced.Finally,key challenges in the industrial production of these carbons are outlined,and future research directions are proposed.These include the establishment of a database of biomass intrinsic structures and machine learning-assisted pore structure engineering,aimed at providing guidance for the design of high-performance carbon materials for next-generation energy storage devices.展开更多
This study analyzes the influence of TiO_(2) and Al_(2)O_(3) contents on the microstructure of CaO-SiO_(2)-MgO-xwt%Al_(2)O_(3)-ywt%TiO_(2)(14≤x≤22,0≤y≤10)blast furnace slag systems based on the change of slag visc...This study analyzes the influence of TiO_(2) and Al_(2)O_(3) contents on the microstructure of CaO-SiO_(2)-MgO-xwt%Al_(2)O_(3)-ywt%TiO_(2)(14≤x≤22,0≤y≤10)blast furnace slag systems based on the change of slag viscosity,Raman spectroscopy,and molecular dynamics.The Raman spectroscopy results indicate that an increase in TiO_(2) content leads to the gradual depolymerization of complex Q_(Si)^(3) Q_(Si)^(2) Q_(Si)^(0) Q_(Si)^(1)silicate structures(and)into simpler structures(and)in the slag.At the same time,the Al-O-Al bonds in the aluminate structures of the slag also depolymerize into simpler Al-O-forms,resulting in a decrease in the degree of polymerization of both silicates and aluminates.In contrast,an increase in Al_(2)O_(3) content generally results in an increased degree of polymerization for the silicates and aluminates.Molecular dynamics simulations of the polymerization and depolymerization processes in the microstructure of the blast fur-nace slag reveal that Si and Al mainly exist in tetrahedral[SiO_(4)]^(4-)and[AlO_(4)]^(4-),while Ti mainly exists in the form of simple pentaco-ordinate[TiO_(5)]^(6-)and hexacoordinate[TiO_(6)]^(8-).TiO_(2) exhibits basic properties in this system,whereas Al_(2)O_(3) demonstrates acidic behavior.The addition of TiO_(2) introduces free oxide ions into the system,causing the bridging oxygens to break into non-bridging oxygens,lead-Q_(Si)^(4) Q_(Si)^(3)ing to the depolymerization of complex structures and,which simplifies the slag structure.On the other hand,an increase in Al_(2)O_(3) content tends to capture or share the oxide ions within the system to form[AlO_(4)]^(4-),resulting in the polymerization of free oxygens into Q_(Si)^(0) Q_(Si)^(1)non-bridging oxygens,which further polymerize into bridging oxygens and lead to the consolidation of simple structures and,resulting in a more complex slag structure.Both Raman spectroscopy analysis and molecular dynamics simulation results indicate that the degree of polymerization of[SiO_(4)]^(4-) and[AlO_(4)]^(4-) in the slag network structure is a crucial factor determining the fluidity of the slag.展开更多
Sodium-ion batteries are the prominent device for stationary energy storage system and low-speed electric vehicles.However,the practical application is still limited by the unsatisfied performance and high cost of the...Sodium-ion batteries are the prominent device for stationary energy storage system and low-speed electric vehicles.However,the practical application is still limited by the unsatisfied performance and high cost of the cathode side,which strictly requires the development of high voltage,high capacity,and earth-abundant cathode material.Ni-Fe-Mn ternary layered oxide has been recognized as one of the most promising standard type of cathodes.However,the composition and phase structure on high-voltage characteristics have not been well investigated.Herein,selecting the typically high-voltage cathode of P2-Na_(0.67)Ni_(0.33)Mn_(0.67)O_(2)as a parent material,we fabricate ten Ni-Fe-Mn ternary layered oxides through replacing the Ni,Mn,or both Ni and Mn by Fe.The thermodynamically stable phase diagram for those materials is presented.The electrochemical properties for all the samples are investigated in detail.Three potential Ni-Fe-Mn ternary layered oxides are picked up considering the energy density,cycle stability,kinetics,cost price,and working voltage,which demonstrate great potential for surpassing the performance of lithium iron phosphate.The related electrochemical reaction and fading mechanism are well revealed.This work provides some new foundational Ni-Fe-Mn ternary layered materials for high-voltage sodium-ion batteries.展开更多
Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and...Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.展开更多
The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb_(7)Ti,which is the only dynamically stab...The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb_(7)Ti,which is the only dynamically stable ordered Nb-Ti compound under ambient pressure.Extensive first-principles calculations have provided insights into the electronic structure,bonding and superconducting properties of Nb_(7)Ti.The superconducting transition temperature(T_(c))for Nb_(7)Ti at ambient pressure is estimated within the framework of BCS theory to be about 17.5 K,which is significantly higher—nearly double—that of the widely utilized NbTi alloy.Furthermore,the results unveil that the high T_(c) is mainly attributed to the unique ordered lattice along with the strong electron-phonon coupling driven by interatomic interactions at mid-frequency and phonon softening induced by low-frequency Fermi surface nesting.Valuable insights are provided for the subsequent synthesis of application-oriented superconductors at low pressure.展开更多
Integrating wave energy converters(WECs)with offshore platforms offers numerous advantages,such as reducing wave loads,supplying energy to the platform,and cost-sharing in construction.This paper reports an experiment...Integrating wave energy converters(WECs)with offshore platforms offers numerous advantages,such as reducing wave loads,supplying energy to the platform,and cost-sharing in construction.This paper reports an experimental investigation focusing on the hydrodynamic characteristics of a proposed modular floating structure system integrated with WEC-type floating artificial reefs.The proposed system comprises several serially arranged hexagonal floating structures,anchored by tension legs,and integrated with outermost WEC-type floating artificial reefs.A simplified wave energy converter utilizing the relative pitch motion between adjacent modules for energy conversion was constructed in the scale model test.The effects of chain-type modular expansion on the multi-body motion response,mooring tension response,and WEC performance of the system have been thoroughly investigated.The experimental results indicate that increasing the number of hexagonal modules can notably reduce the system’s surge response,particularly under survival sea conditions.The connection of the outermost reef modules slightly increases the tension leg load of the adjacent module,whereas the tension leg load remains relatively consistent across the inner hexagonal modules.Furthermore,through a comparison of the dynamic responses of the hexagonal module connected and unconnected outermost reefs,the good performance in terms of energy conversion and wave attenuation of the WECtype floating artificial reef modules was effectively validated.The main results from this work can provide useful references for engineering applications involving modular floating structures integrated with WECs.展开更多
Currently,the Al_(2)O_(3)content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%,making it challenging to overcome this limitation.Unlike most studies that concentrated on...Currently,the Al_(2)O_(3)content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%,making it challenging to overcome this limitation.Unlike most studies that concentrated on managing the MgO/Al_(2)O_(3)ratio or basicity,this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO-MgO-Al_(2)O_(3)-SiO_(2)slag system,providing theoretical guidance and data to facilitate the application of high-alumina ores.The results revealed that the viscosity first decreased and then increased with higher MgO substitution,reaching a minimum at 15mol%MgO concentration.Fourier transform infrared spectroscopy(FTIR)results found that the depths of the troughs representing[SiO_(4)]tetrahedra,[AlO_(4)]tetrahedra,and Si-O-Al bending became progressively deeper with increased MgO substitution.Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the X_(Q^(3))/X_(Q^(2))(X_(Q^(i))is the molar fraction of Q^(i) unit,and i is the number of bridging oxygens in a[SiO_(4)]tetrahedral unit)ratio increased from 2.30 and 1.02 to 2.52 and 2.14,respectively,indicating a progressive polymerization of the silicate structure.X-ray photoelectron spectroscopy(XPS)results highlighted that non-bridging oxygen content decreased from 77.97mol% to 63.41mol% with increasing MgO concentration,whereas bridging oxygen and free oxygen contents increased.Structural analysis demonstrated a gradual increase in the polymerization degree of the tetrahedral structure with the increase in MgO substitution.However,bond strength is another important factor affecting the slag viscosity.The occurrence of a viscosity minimum can be attributed to the complex evolution of bond strengths of non-bridging oxygens generated during depolymerization of the[SiO_(4)]and[AlO_(4)]tetrahedral structures by CaO and MgO.展开更多
In order to provide a method for accurately detecting the concentration and types of heavy metal ions in water,a fluid ion detection system is designed.It consists of a side-polished fiber-assisted fluid structure and...In order to provide a method for accurately detecting the concentration and types of heavy metal ions in water,a fluid ion detection system is designed.It consists of a side-polished fiber-assisted fluid structure and a long-period fiber grating(LPFG)coated with a metal chelating agent membrane.In this study,both theoretical and experimental investigations are conducted to examine the sensing characteristics of the system towards copper ion and iron ion solutions.The results demonstrate that under the premise of ensuring solution flow,the system can achieve specific identification of different types of heavy metal ions.Furthermore,it exhibits concentration sensing sensitivities of 9.23×10^(4) mL·nm/mol and 7.13×10^(4) mL·nm/mol for copper sulfate(CuSO_(4))and ferric chloride(FeCl_(3))solutions,respectively.Therefore,this sensing system offers the potential for real-time detection of metal ions.展开更多
In this paper, we propose a novel anomaly detection method for data centers based on a combination of graphstructure and abnormal attention mechanism. The method leverages the sensor monitoring data from targetpower s...In this paper, we propose a novel anomaly detection method for data centers based on a combination of graphstructure and abnormal attention mechanism. The method leverages the sensor monitoring data from targetpower substations to construct multidimensional time series. These time series are subsequently transformed intograph structures, and corresponding adjacency matrices are obtained. By incorporating the adjacency matricesand additional weights associated with the graph structure, an aggregation matrix is derived. The aggregationmatrix is then fed into a pre-trained graph convolutional neural network (GCN) to extract graph structure features.Moreover, both themultidimensional time series segments and the graph structure features are inputted into a pretrainedanomaly detectionmodel, resulting in corresponding anomaly detection results that help identify abnormaldata. The anomaly detection model consists of a multi-level encoder-decoder module, wherein each level includesa transformer encoder and decoder based on correlation differences. The attention module in the encoding layeradopts an abnormal attention module with a dual-branch structure. Experimental results demonstrate that ourproposed method significantly improves the accuracy and stability of anomaly detection.展开更多
A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in th...A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in the breech chamber,and the other is arranged in the barrel.The breech chamber charge was ignited first,and the charges in the auxiliary chambers were ignited by the high-temperature,highpressure combustible gas trailing the projectile.In this way,the combustible gas in the auxiliary chambers could compensate for the pressure drop caused by the movement of the projectile.The proposed device features the advantage of launching a projectile with high muzzle velocity without exceeding the maximum pressure in the chamber.In order to obtain some internal ballistic characteristics of the launch system,some critical structure,such as the length of the filter cartridge auxiliary charge,the combustion degree of the propellant in the chamber,and the length of the barrel,are discussed.The experimental results show that with the increased auxiliary charge length,a pressure plateau or even a secondary peak pressure can be formed,which is less than the peak pressure.The projectile velocity increased by 23.57%,14.64%,and 7.65%when the diaphragm thickness was 0 mm,1 mm,and2 mm,respectively.The muzzle velocity of the projectile can be increased by 13.42%by increasing the length of the barrel.Under the same charge condition,with the increase of barrel length,the energy utilization rate of propellant increases by 28.64%.展开更多
In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular...In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.展开更多
To enhance the mechanical properties of polypropylene random copolymer(PPR),polystyrene(PS)with four different contents were added to the PPR matrix through melt blending.Subsequently,using the Multi-Flow Vibration In...To enhance the mechanical properties of polypropylene random copolymer(PPR),polystyrene(PS)with four different contents were added to the PPR matrix through melt blending.Subsequently,using the Multi-Flow Vibration Injection Molding(MFVIM)technology,PPR/PS in situ microfiber composites(MFC)with different blending ratios were prepared.The results indicated that blending ratio had a great impact on the phase morphology and crystal structure of MFVIM samples,which was different from those of conventional injection molding(CIM)samples.PS ultrafine fibers could be formed under the shear field and could absorb the PPR molecular chains to form hybrid shish-kebab structures.Meanwhile,the PPR matrix could also form shish-kebab structures under the effect of strong shear.When the PS content reached 20%,under the combined action of PS in situ microfibers and highly oriented crystal structure,the tensile strength and Young’s modulus of the sample were obviously improved and the impact strength remained at a relatively high level.So a strong and tough balanced PPR based material was obtained.These results provide valuable insights for expanding the industrial and daily-life applications of PPR and show promising development prospects.展开更多
In this study,a novel equivalent damping ratio model that is suitable for reinforced concrete(RC)structures considering cyclic degradation behavior is developed,and a new equivalent linearization analysis method for i...In this study,a novel equivalent damping ratio model that is suitable for reinforced concrete(RC)structures considering cyclic degradation behavior is developed,and a new equivalent linearization analysis method for implementing the proposed equivalent damping ratio model for use in seismic damage evaluation is presented.To this end,Ibarra’s peak-oriented model,which incorporates an energy-based degradation rule,is selected for representing hysteretic behavior of RC structure,and the optimized equivalent damping for predicting the maximum displacement response is presented by using the empirical method,in which the effect of cyclic degradation is considered.Moreover,the relationship between the hysteretic energy dissipation of the inelastic system and the elastic strain energy of the equivalent linear system is established so that the proposed equivalent linear system can be directly integrated with the Park-Ang seismic model to implement seismic damage evaluation.Due to the simplicity of the equivalent linearization method,the proposed method provides an efficient and reliable way of obtaining comprehensive insight into the seismic performance of RC structures.The verification demonstrates the validity of the proposed method.展开更多
With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite h...With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.展开更多
The elimination of neonicotinoids(NEOs)from water has been a research priority due to their threats to human health and ecosystems.In this study,we established the heterogeneous peroxymonosulfate(PMS)activation system...The elimination of neonicotinoids(NEOs)from water has been a research priority due to their threats to human health and ecosystems.In this study,we established the heterogeneous peroxymonosulfate(PMS)activation system using manganese catalyst(Mn NC)and cobalt catalyst(Co NC)to trigger the nonradical oxidation and synergistic oxidation pathway,respectively to remove NEOs.The results showed that the nonradical oxidation system exhibited superior NEOs degradation capability.The composition of organic pollutants in wastewater significantly impacted subsequent degradation processes.The charge distribution and reaction sites of various NEOs were analyzed using density functional theory(DFT)calculations,and it demonstrated the electron distribution and activity of NEOs were significantly influenced by the type and number of substituents.Nitro group(–NO_(2))and cyanide group(–C≡N)were identified as strong electron-withdrawing groups and prone to be attacked by negatively charged radicals.The transformation of NEOs was analyzed,and result showed that the C and N sites adjacent to the nitro group and cyanide group were more susceptible to oxidation attacks.S and N atoms,which possess strong electronegativity and high electron cloud density,were identified as key active sites in the degradation pathway.The outcomes of this study provide valuable guidance for the oriented regulation of oxidation pathways towards efficient removal of NEOs in water.展开更多
Cracks,potholes,and other defects often occur on infrastructure such as bridges,among which cracks are one of the most frequent defects.They have diverse shapes and are difficult to detect.Traditional manual inspectio...Cracks,potholes,and other defects often occur on infrastructure such as bridges,among which cracks are one of the most frequent defects.They have diverse shapes and are difficult to detect.Traditional manual inspection methods are inefficient and have low accuracy,while automated inspection machines are bulky and inconvenient to carry and use.Based on the shortcomings of existing detection technologies,this paper proposes a portable structural surface crack detection system based on the Android platform using a portable hand-held image acquisition device.The system captures cracks on the structure's surface and obtains high-definition crack images.Then,these images are transmitted to portable smartphone terminals through Wi-Fi.Next,the image is pre-processed using weighted averaging,grayscale linear transformation,and adaptive median filtering.Then,the improved Canny edge detection algorithm is applied to identify crack information,and the edge segmentation algorithm is used to determine the crack width.Finally,based on camera calibration,the pixels are converted into the length data required for actual measurement.The results show that the system is easy to operate,and it not only has crack storage and tracking functions,but also can effectively measure the crack width on the surface of components.The measurement accuracy of this system reaches the sub-pixel level,and in actual testing,compared with the crack width gauge,the maximum relative error does notexceed6.25%.展开更多
Internal polyhedral structures of a granular system can be investigated using the Voronoi tessellations.This technique has gained increasing recognition in research of kinetic properties of granular flows.For systems ...Internal polyhedral structures of a granular system can be investigated using the Voronoi tessellations.This technique has gained increasing recognition in research of kinetic properties of granular flows.For systems with mono-sized spherical particles,Voronoi tessellations can be utilized,while radial Voronoi tessellations are necessary for analyzing systems with multi-sized spherical particles.However,research about polyhedral structures of non-spherical particle systems is limited.We utilize the discrete element method to simulate a system of ellipsoidal particles,defined by the equation(x/a)^(2)+(y/1)^(2)+(z/1/a)^(2)=1,where a ranges from 1.1 to 2.0.The system is then dissected by using tangent planes at the contact points,and the geometric quantities of the resulting polyhedra in different shaped systems,such as surface area,volume,number of vertices,number of edges,and number of faces,are calculated.Meanwhile,the longitudinal and transverse wave velocities within the system are calculated with the time-of-flight method.The results demonstrate a strong correlation between the sound velocity of the system and the geometry of the dissected polyhedra.The sound velocity of the system increases with the increase in a,peaking at a=1.3,and then decreases as a continues to increase.The average volume,surface area,number of vertices,number of edges,and number of faces of the polyhedra decrease with the increase in sound velocity.That is,these quantities initially decrease with the increase in a,reaching minima at a=1.3,and then increase with further increase of a.The relationship between sound velocity and the geometric quantities of the dissected polyhedra can serve as a reference for acoustic material design.展开更多
The determination of stress distribution is important for the safe use of membrane structures in practical engineering,which is difficult to be obtained by existing measurement methods and analysis methods.This paper ...The determination of stress distribution is important for the safe use of membrane structures in practical engineering,which is difficult to be obtained by existing measurement methods and analysis methods.This paper proposes a rigid-membrane method to determine the stress distribution of the membrane,which expands the stiffness of the membrane,applies the load of the membrane in equilibrium to the membrane shape of the equilibrium state,and performs nonlinear finite element analysis.The rigid-membrane method inversely acquires the stress distribution of the membrane based only on the shape and load distribution in equilibrium obtained from the numerical simulation of a membrane structure under water loads,and determines the modulus magnitude and mesh size required to rigidize the membrane.The accuracy of the rigid-membrane method is verified by the small differences between the stress distributions obtained from the proposed method and numerical simulations.The equilibrium membrane shape in the actual project can be scanned and reconstructed by the laser scanner system without any pre-processing,and the load is determined by the water level,internal pressure,etc.Based on the actual membrane shape and water load distribution,the rigid-membrane method determines the real stress distribution of the membrane in the test of flat membrane subjected to ponding water,which verifies that the rigid-membrane method is a practical method to determine the stress distribution only by the membrane shape and external load distribution.展开更多
The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical models.B...The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical models.Based on the deep seismic tomography using long-period natural earthquake data,in this study,the deep structure and material circulation of the curved subduction system in Southeast Asia was studied,and the dynamic processes since 100 million years ago was reconstructed.It is pointed out that challenges still exist in the precise reconstruction of deep mantle structures of the study area,the influence of multi-stage subduction on deep material exchange and shallow magma activity,as well as the spatiotemporal evolution and coupling mechanism of multi-plate convergence.Future work should focus on high-resolution land-sea joint 3-D seismic tomography imaging of the curved subduction system in the Southeast Asia,combined with geochemical analysis and geodynamic modelling works.展开更多
文摘The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and fluid mobility due to the influences of the northeast and northwest dual provenance systems.This study performed multiple experimental analyses on nine samples from the area to determine the petrological and petrophysical properties,as well as the PTS characteristics of reservoirs in different provenance-controlled regions.On this basis,the pore-throat size distribution(PSD)obtained from high-pressure mercury injection(HPMI)was utilized to convert the NMR movable fluid T2spectrum,allowing for quantitative characterization of the full PSD and the occurrence characteristics of movable fluids.A systematic analysis was conducted on the primary controlling factors affecting fluid mobility in the reservoir.The results indicated that the lithology in the eastern and western regions is lithic arkose.The eastern sandstones,being farther from the provenance,exhibit higher contents of feldspar and lithic fragments,along with the development of more dissolution pores.The reservoir possesses good petrophysical properties,low displacement pressure,and high pore-throat connectivity and homogeneity,indicating strong fluid mobility.In contrast,the western sandstones,being nearer to the provenance,exhibit poor grain sorting,high contents of lithic fragments,strong compaction and cementation effects,resulting in poor petrophysical properties,and strong pore-throat heterogeneity,revealing weak fluid mobility.The range of full PSD in the eastern reservoir is wider than that in the western reservoir,with relatively well-developed macropores.The macropores are the primary space for occurrence of movable fluids,and controls the fluid mobility of the reservoir.The effective porosity of movable fluids(EPMF)quantitatively represents the pore space occupied by movable fluids within the reservoir and correlates well with porosity,permeability,and PTS parameters,making it a valuable parameter for evaluating fluid mobility.Under the multi-provenance system,the eastern and western reservoirs underwent different sedimentation and diagenesis processes,resulting in differential distribution of reservoir mineral components and pore types,which in turn affects the PTS heterogeneity and reservoir quality.The composition and content of reservoir minerals are intrinsic factors influencing fluid mobility,while the microscopic PTS is the primary factor controlling it.Low clay mineral content,welldeveloped macropores,and weak pore-throat heterogeneity all contribute to the storage and seepage of reservoir fluids.
文摘The development of sustainable electrode materials for energy storage systems has become very important and porous carbons derived from biomass have become an important candidate because of their tunable pore structure,environmental friendliness,and cost-effectiveness.Recent advances in controlling the pore structure of these carbons and its relationship between to is energy storage performance are discussed,emphasizing the critical role of a balanced distribution of micropores,mesopores and macropores in determining electrochemical behavior.Particular attention is given to how the intrinsic components of biomass precursors(lignin,cellulose,and hemicellulose)influence pore formation during carbonization.Carbonization and activation strategies to precisely control the pore structure are introduced.Finally,key challenges in the industrial production of these carbons are outlined,and future research directions are proposed.These include the establishment of a database of biomass intrinsic structures and machine learning-assisted pore structure engineering,aimed at providing guidance for the design of high-performance carbon materials for next-generation energy storage devices.
基金financially supported by the National Natural Science Foundation of China(No.52174299)the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization,China(No.2024P4FZG10).
文摘This study analyzes the influence of TiO_(2) and Al_(2)O_(3) contents on the microstructure of CaO-SiO_(2)-MgO-xwt%Al_(2)O_(3)-ywt%TiO_(2)(14≤x≤22,0≤y≤10)blast furnace slag systems based on the change of slag viscosity,Raman spectroscopy,and molecular dynamics.The Raman spectroscopy results indicate that an increase in TiO_(2) content leads to the gradual depolymerization of complex Q_(Si)^(3) Q_(Si)^(2) Q_(Si)^(0) Q_(Si)^(1)silicate structures(and)into simpler structures(and)in the slag.At the same time,the Al-O-Al bonds in the aluminate structures of the slag also depolymerize into simpler Al-O-forms,resulting in a decrease in the degree of polymerization of both silicates and aluminates.In contrast,an increase in Al_(2)O_(3) content generally results in an increased degree of polymerization for the silicates and aluminates.Molecular dynamics simulations of the polymerization and depolymerization processes in the microstructure of the blast fur-nace slag reveal that Si and Al mainly exist in tetrahedral[SiO_(4)]^(4-)and[AlO_(4)]^(4-),while Ti mainly exists in the form of simple pentaco-ordinate[TiO_(5)]^(6-)and hexacoordinate[TiO_(6)]^(8-).TiO_(2) exhibits basic properties in this system,whereas Al_(2)O_(3) demonstrates acidic behavior.The addition of TiO_(2) introduces free oxide ions into the system,causing the bridging oxygens to break into non-bridging oxygens,lead-Q_(Si)^(4) Q_(Si)^(3)ing to the depolymerization of complex structures and,which simplifies the slag structure.On the other hand,an increase in Al_(2)O_(3) content tends to capture or share the oxide ions within the system to form[AlO_(4)]^(4-),resulting in the polymerization of free oxygens into Q_(Si)^(0) Q_(Si)^(1)non-bridging oxygens,which further polymerize into bridging oxygens and lead to the consolidation of simple structures and,resulting in a more complex slag structure.Both Raman spectroscopy analysis and molecular dynamics simulation results indicate that the degree of polymerization of[SiO_(4)]^(4-) and[AlO_(4)]^(4-) in the slag network structure is a crucial factor determining the fluidity of the slag.
基金financially supported by the National Natural Science Foundation of China(Grant No.52402215)the Anhui Provincial Natural Science Foundation(2408085QB036)+1 种基金the Natural Science Research Project of Anhui Province Education Department(Grant Nos.2022AH050334,2022AH030046,2023AH051119)the Scientific Research Foundation of Anhui University of Technology for Talent Introduction(DT2200001211)。
文摘Sodium-ion batteries are the prominent device for stationary energy storage system and low-speed electric vehicles.However,the practical application is still limited by the unsatisfied performance and high cost of the cathode side,which strictly requires the development of high voltage,high capacity,and earth-abundant cathode material.Ni-Fe-Mn ternary layered oxide has been recognized as one of the most promising standard type of cathodes.However,the composition and phase structure on high-voltage characteristics have not been well investigated.Herein,selecting the typically high-voltage cathode of P2-Na_(0.67)Ni_(0.33)Mn_(0.67)O_(2)as a parent material,we fabricate ten Ni-Fe-Mn ternary layered oxides through replacing the Ni,Mn,or both Ni and Mn by Fe.The thermodynamically stable phase diagram for those materials is presented.The electrochemical properties for all the samples are investigated in detail.Three potential Ni-Fe-Mn ternary layered oxides are picked up considering the energy density,cycle stability,kinetics,cost price,and working voltage,which demonstrate great potential for surpassing the performance of lithium iron phosphate.The related electrochemical reaction and fading mechanism are well revealed.This work provides some new foundational Ni-Fe-Mn ternary layered materials for high-voltage sodium-ion batteries.
基金Supported by the National Science and Technology Major Project of China(2024ZD1400101)China National Key Research and Development Project(2022YFF0801204)Major Science and Technology Project of CNPC(2023ZZ15YJ01,2021DJ0702)。
文摘Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.
基金supported by the National Natural Science Foundation of China(Grant Nos.12122405,12274169,and 11574109)the Fundamental Research Funds for the Central Universities。
文摘The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb_(7)Ti,which is the only dynamically stable ordered Nb-Ti compound under ambient pressure.Extensive first-principles calculations have provided insights into the electronic structure,bonding and superconducting properties of Nb_(7)Ti.The superconducting transition temperature(T_(c))for Nb_(7)Ti at ambient pressure is estimated within the framework of BCS theory to be about 17.5 K,which is significantly higher—nearly double—that of the widely utilized NbTi alloy.Furthermore,the results unveil that the high T_(c) is mainly attributed to the unique ordered lattice along with the strong electron-phonon coupling driven by interatomic interactions at mid-frequency and phonon softening induced by low-frequency Fermi surface nesting.Valuable insights are provided for the subsequent synthesis of application-oriented superconductors at low pressure.
基金financially supported by the National Natural Science Foundation of China(Grant No.52161041)the Natural Science Foundation of Hainan Province(Grant No.520RC552).
文摘Integrating wave energy converters(WECs)with offshore platforms offers numerous advantages,such as reducing wave loads,supplying energy to the platform,and cost-sharing in construction.This paper reports an experimental investigation focusing on the hydrodynamic characteristics of a proposed modular floating structure system integrated with WEC-type floating artificial reefs.The proposed system comprises several serially arranged hexagonal floating structures,anchored by tension legs,and integrated with outermost WEC-type floating artificial reefs.A simplified wave energy converter utilizing the relative pitch motion between adjacent modules for energy conversion was constructed in the scale model test.The effects of chain-type modular expansion on the multi-body motion response,mooring tension response,and WEC performance of the system have been thoroughly investigated.The experimental results indicate that increasing the number of hexagonal modules can notably reduce the system’s surge response,particularly under survival sea conditions.The connection of the outermost reef modules slightly increases the tension leg load of the adjacent module,whereas the tension leg load remains relatively consistent across the inner hexagonal modules.Furthermore,through a comparison of the dynamic responses of the hexagonal module connected and unconnected outermost reefs,the good performance in terms of energy conversion and wave attenuation of the WECtype floating artificial reef modules was effectively validated.The main results from this work can provide useful references for engineering applications involving modular floating structures integrated with WECs.
基金financially supported by the National Natural Science Foundation of China(Nos.52425408 and 52304345)the Fundamental Research Funds for the Central Universities,China(No.2023CDJXY-016)the Postdoctoral Science Foundation of Chongqing(No.CSTB2023NSCQ-BHX0174)。
文摘Currently,the Al_(2)O_(3)content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%,making it challenging to overcome this limitation.Unlike most studies that concentrated on managing the MgO/Al_(2)O_(3)ratio or basicity,this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO-MgO-Al_(2)O_(3)-SiO_(2)slag system,providing theoretical guidance and data to facilitate the application of high-alumina ores.The results revealed that the viscosity first decreased and then increased with higher MgO substitution,reaching a minimum at 15mol%MgO concentration.Fourier transform infrared spectroscopy(FTIR)results found that the depths of the troughs representing[SiO_(4)]tetrahedra,[AlO_(4)]tetrahedra,and Si-O-Al bending became progressively deeper with increased MgO substitution.Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the X_(Q^(3))/X_(Q^(2))(X_(Q^(i))is the molar fraction of Q^(i) unit,and i is the number of bridging oxygens in a[SiO_(4)]tetrahedral unit)ratio increased from 2.30 and 1.02 to 2.52 and 2.14,respectively,indicating a progressive polymerization of the silicate structure.X-ray photoelectron spectroscopy(XPS)results highlighted that non-bridging oxygen content decreased from 77.97mol% to 63.41mol% with increasing MgO concentration,whereas bridging oxygen and free oxygen contents increased.Structural analysis demonstrated a gradual increase in the polymerization degree of the tetrahedral structure with the increase in MgO substitution.However,bond strength is another important factor affecting the slag viscosity.The occurrence of a viscosity minimum can be attributed to the complex evolution of bond strengths of non-bridging oxygens generated during depolymerization of the[SiO_(4)]and[AlO_(4)]tetrahedral structures by CaO and MgO.
基金supported by the National Natural Science Foundation of China(Nos.61705027,62005033,11704053 and 52175531)the Basic Research Project of Chongqing Science and Technology Commission(No.CSTC-2020jcyj-msxm0603)the Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202000609 and KJZD-M202000602)。
文摘In order to provide a method for accurately detecting the concentration and types of heavy metal ions in water,a fluid ion detection system is designed.It consists of a side-polished fiber-assisted fluid structure and a long-period fiber grating(LPFG)coated with a metal chelating agent membrane.In this study,both theoretical and experimental investigations are conducted to examine the sensing characteristics of the system towards copper ion and iron ion solutions.The results demonstrate that under the premise of ensuring solution flow,the system can achieve specific identification of different types of heavy metal ions.Furthermore,it exhibits concentration sensing sensitivities of 9.23×10^(4) mL·nm/mol and 7.13×10^(4) mL·nm/mol for copper sulfate(CuSO_(4))and ferric chloride(FeCl_(3))solutions,respectively.Therefore,this sensing system offers the potential for real-time detection of metal ions.
基金the Science and Technology Project of China Southern Power Grid Company,Ltd.(031200KK52200003)the National Natural Science Foundation of China(Nos.62371253,52278119).
文摘In this paper, we propose a novel anomaly detection method for data centers based on a combination of graphstructure and abnormal attention mechanism. The method leverages the sensor monitoring data from targetpower substations to construct multidimensional time series. These time series are subsequently transformed intograph structures, and corresponding adjacency matrices are obtained. By incorporating the adjacency matricesand additional weights associated with the graph structure, an aggregation matrix is derived. The aggregationmatrix is then fed into a pre-trained graph convolutional neural network (GCN) to extract graph structure features.Moreover, both themultidimensional time series segments and the graph structure features are inputted into a pretrainedanomaly detectionmodel, resulting in corresponding anomaly detection results that help identify abnormaldata. The anomaly detection model consists of a multi-level encoder-decoder module, wherein each level includesa transformer encoder and decoder based on correlation differences. The attention module in the encoding layeradopts an abnormal attention module with a dual-branch structure. Experimental results demonstrate that ourproposed method significantly improves the accuracy and stability of anomaly detection.
基金financially supported by the National Natural Science Foundation of China under Project No.51874267 and No.12272374the Fundamental Research Funds for the Central Universities under Project Nos.WK2480000008,WK2480000007,and WK2320000049。
文摘A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in the breech chamber,and the other is arranged in the barrel.The breech chamber charge was ignited first,and the charges in the auxiliary chambers were ignited by the high-temperature,highpressure combustible gas trailing the projectile.In this way,the combustible gas in the auxiliary chambers could compensate for the pressure drop caused by the movement of the projectile.The proposed device features the advantage of launching a projectile with high muzzle velocity without exceeding the maximum pressure in the chamber.In order to obtain some internal ballistic characteristics of the launch system,some critical structure,such as the length of the filter cartridge auxiliary charge,the combustion degree of the propellant in the chamber,and the length of the barrel,are discussed.The experimental results show that with the increased auxiliary charge length,a pressure plateau or even a secondary peak pressure can be formed,which is less than the peak pressure.The projectile velocity increased by 23.57%,14.64%,and 7.65%when the diaphragm thickness was 0 mm,1 mm,and2 mm,respectively.The muzzle velocity of the projectile can be increased by 13.42%by increasing the length of the barrel.Under the same charge condition,with the increase of barrel length,the energy utilization rate of propellant increases by 28.64%.
基金supported by National Natural Science Foundation of China,China(No.51901117,51801116)Youth Innovation and Technology Support Program of Shandong Provincial Colleges and Universities,China(No.2020KJA002)+2 种基金Youth Fund of Shandong Academy of Sciences,China(2020QN0021)Innovation Pilot Project for Fusion of Science,Education and Industry(International Cooperation)from Qilu University of Technology(Shandong Academy of Sciences),China(No.2020KJC-GH03)Several Policies on Promoting Collaborative Innovation and Industrialization of Achievements in Universities and Research Institutes,China(No.2019GXRC030)。
文摘In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.
基金supported by the National Natural Science Foundation of China(No.21627804).
文摘To enhance the mechanical properties of polypropylene random copolymer(PPR),polystyrene(PS)with four different contents were added to the PPR matrix through melt blending.Subsequently,using the Multi-Flow Vibration Injection Molding(MFVIM)technology,PPR/PS in situ microfiber composites(MFC)with different blending ratios were prepared.The results indicated that blending ratio had a great impact on the phase morphology and crystal structure of MFVIM samples,which was different from those of conventional injection molding(CIM)samples.PS ultrafine fibers could be formed under the shear field and could absorb the PPR molecular chains to form hybrid shish-kebab structures.Meanwhile,the PPR matrix could also form shish-kebab structures under the effect of strong shear.When the PS content reached 20%,under the combined action of PS in situ microfibers and highly oriented crystal structure,the tensile strength and Young’s modulus of the sample were obviously improved and the impact strength remained at a relatively high level.So a strong and tough balanced PPR based material was obtained.These results provide valuable insights for expanding the industrial and daily-life applications of PPR and show promising development prospects.
基金National Natural Science Foundation of China under Grant No.51978125Open Fund Project of Research Center for Geotechnical and Structural Engineering Technology of Liaoning Province under Grant No.DLSZD2023[007]。
文摘In this study,a novel equivalent damping ratio model that is suitable for reinforced concrete(RC)structures considering cyclic degradation behavior is developed,and a new equivalent linearization analysis method for implementing the proposed equivalent damping ratio model for use in seismic damage evaluation is presented.To this end,Ibarra’s peak-oriented model,which incorporates an energy-based degradation rule,is selected for representing hysteretic behavior of RC structure,and the optimized equivalent damping for predicting the maximum displacement response is presented by using the empirical method,in which the effect of cyclic degradation is considered.Moreover,the relationship between the hysteretic energy dissipation of the inelastic system and the elastic strain energy of the equivalent linear system is established so that the proposed equivalent linear system can be directly integrated with the Park-Ang seismic model to implement seismic damage evaluation.Due to the simplicity of the equivalent linearization method,the proposed method provides an efficient and reliable way of obtaining comprehensive insight into the seismic performance of RC structures.The verification demonstrates the validity of the proposed method.
基金sponsored by National Natural Science Foundation of China(No.52302121,No.52203386)Shanghai Sailing Program(No.23YF1454700)+1 种基金Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664).
文摘With vigorous developments in nanotechnology,the elaborate regulation of microstructure shows attractive potential in the design of electromagnetic wave absorbers.Herein,a hierarchical porous structure and composite heterogeneous interface are constructed successfully to optimize the electromagnetic loss capacity.The macro–micro-synergistic graphene aerogel formed by the ice template‑assisted 3D printing strategy is cut by silicon carbide nanowires(SiC_(nws))grown in situ,while boron nitride(BN)interfacial structure is introduced on graphene nanoplates.The unique composite structure forces multiple scattering of incident EMWs,ensuring the combined effects of interfacial polarization,conduction networks,and magnetic-dielectric synergy.Therefore,the as-prepared composites present a minimum reflection loss value of−37.8 dB and a wide effective absorption bandwidth(EAB)of 9.2 GHz(from 8.8 to 18.0 GHz)at 2.5 mm.Besides,relying on the intrinsic high-temperature resistance of SiC_(nws) and BN,the EAB also remains above 5.0 GHz after annealing in air environment at 600℃ for 10 h.
基金funded by National Natural Science Foundation of China(No.42177382)。
文摘The elimination of neonicotinoids(NEOs)from water has been a research priority due to their threats to human health and ecosystems.In this study,we established the heterogeneous peroxymonosulfate(PMS)activation system using manganese catalyst(Mn NC)and cobalt catalyst(Co NC)to trigger the nonradical oxidation and synergistic oxidation pathway,respectively to remove NEOs.The results showed that the nonradical oxidation system exhibited superior NEOs degradation capability.The composition of organic pollutants in wastewater significantly impacted subsequent degradation processes.The charge distribution and reaction sites of various NEOs were analyzed using density functional theory(DFT)calculations,and it demonstrated the electron distribution and activity of NEOs were significantly influenced by the type and number of substituents.Nitro group(–NO_(2))and cyanide group(–C≡N)were identified as strong electron-withdrawing groups and prone to be attacked by negatively charged radicals.The transformation of NEOs was analyzed,and result showed that the C and N sites adjacent to the nitro group and cyanide group were more susceptible to oxidation attacks.S and N atoms,which possess strong electronegativity and high electron cloud density,were identified as key active sites in the degradation pathway.The outcomes of this study provide valuable guidance for the oriented regulation of oxidation pathways towards efficient removal of NEOs in water.
基金Supported by Shaanxi Provincial Key Research and Development Program(2024GX-YBXM-288)the National Natural Science Foundation of China(52172324)+1 种基金Beilin District Science and Technology Program(GX2350)the Special Fund Project for Basic Research Business Expenses of Central level Public Welfare Research Institutes(2023-9062)。
文摘Cracks,potholes,and other defects often occur on infrastructure such as bridges,among which cracks are one of the most frequent defects.They have diverse shapes and are difficult to detect.Traditional manual inspection methods are inefficient and have low accuracy,while automated inspection machines are bulky and inconvenient to carry and use.Based on the shortcomings of existing detection technologies,this paper proposes a portable structural surface crack detection system based on the Android platform using a portable hand-held image acquisition device.The system captures cracks on the structure's surface and obtains high-definition crack images.Then,these images are transmitted to portable smartphone terminals through Wi-Fi.Next,the image is pre-processed using weighted averaging,grayscale linear transformation,and adaptive median filtering.Then,the improved Canny edge detection algorithm is applied to identify crack information,and the edge segmentation algorithm is used to determine the crack width.Finally,based on camera calibration,the pixels are converted into the length data required for actual measurement.The results show that the system is easy to operate,and it not only has crack storage and tracking functions,but also can effectively measure the crack width on the surface of components.The measurement accuracy of this system reaches the sub-pixel level,and in actual testing,compared with the crack width gauge,the maximum relative error does notexceed6.25%.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12262005,11962003,and 11602062)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(Grant No.YJS2024AL138)the Graduate Education Reform Project of Henan Province(Grant No.2023SJGLX096Y).
文摘Internal polyhedral structures of a granular system can be investigated using the Voronoi tessellations.This technique has gained increasing recognition in research of kinetic properties of granular flows.For systems with mono-sized spherical particles,Voronoi tessellations can be utilized,while radial Voronoi tessellations are necessary for analyzing systems with multi-sized spherical particles.However,research about polyhedral structures of non-spherical particle systems is limited.We utilize the discrete element method to simulate a system of ellipsoidal particles,defined by the equation(x/a)^(2)+(y/1)^(2)+(z/1/a)^(2)=1,where a ranges from 1.1 to 2.0.The system is then dissected by using tangent planes at the contact points,and the geometric quantities of the resulting polyhedra in different shaped systems,such as surface area,volume,number of vertices,number of edges,and number of faces,are calculated.Meanwhile,the longitudinal and transverse wave velocities within the system are calculated with the time-of-flight method.The results demonstrate a strong correlation between the sound velocity of the system and the geometry of the dissected polyhedra.The sound velocity of the system increases with the increase in a,peaking at a=1.3,and then decreases as a continues to increase.The average volume,surface area,number of vertices,number of edges,and number of faces of the polyhedra decrease with the increase in sound velocity.That is,these quantities initially decrease with the increase in a,reaching minima at a=1.3,and then increase with further increase of a.The relationship between sound velocity and the geometric quantities of the dissected polyhedra can serve as a reference for acoustic material design.
基金the National Natural Science Foundation of China(No.51978395)。
文摘The determination of stress distribution is important for the safe use of membrane structures in practical engineering,which is difficult to be obtained by existing measurement methods and analysis methods.This paper proposes a rigid-membrane method to determine the stress distribution of the membrane,which expands the stiffness of the membrane,applies the load of the membrane in equilibrium to the membrane shape of the equilibrium state,and performs nonlinear finite element analysis.The rigid-membrane method inversely acquires the stress distribution of the membrane based only on the shape and load distribution in equilibrium obtained from the numerical simulation of a membrane structure under water loads,and determines the modulus magnitude and mesh size required to rigidize the membrane.The accuracy of the rigid-membrane method is verified by the small differences between the stress distributions obtained from the proposed method and numerical simulations.The equilibrium membrane shape in the actual project can be scanned and reconstructed by the laser scanner system without any pre-processing,and the load is determined by the water level,internal pressure,etc.Based on the actual membrane shape and water load distribution,the rigid-membrane method determines the real stress distribution of the membrane in the test of flat membrane subjected to ponding water,which verifies that the rigid-membrane method is a practical method to determine the stress distribution only by the membrane shape and external load distribution.
基金Support by the National Natural Science Foundation of China(No.92258303)the Project of Donghai Laboratory(No.DH-2022ZY0005)。
文摘The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical models.Based on the deep seismic tomography using long-period natural earthquake data,in this study,the deep structure and material circulation of the curved subduction system in Southeast Asia was studied,and the dynamic processes since 100 million years ago was reconstructed.It is pointed out that challenges still exist in the precise reconstruction of deep mantle structures of the study area,the influence of multi-stage subduction on deep material exchange and shallow magma activity,as well as the spatiotemporal evolution and coupling mechanism of multi-plate convergence.Future work should focus on high-resolution land-sea joint 3-D seismic tomography imaging of the curved subduction system in the Southeast Asia,combined with geochemical analysis and geodynamic modelling works.
