The inferior conductivity and drastic volume expansion of silicon still remain the bottleneck in achieving high energy density Lithium-ion Batteries(LIBs).The design of the three-dimensional structure of electrodes by...The inferior conductivity and drastic volume expansion of silicon still remain the bottleneck in achieving high energy density Lithium-ion Batteries(LIBs).The design of the three-dimensional structure of electrodes by compositing silicon and carbon materials has been employed to tackle the above challenges,however,the exorbitant costs and the uncertainty of the conductive structure persist,leaving ample room for improvement.Herein,silicon nanoparticles were innovatively composited with eco-friendly biochar sourced from cotton to fabricate a 3D globally consecutive conductive network.The network serves a dual purpose:enhancing overall electrode conductivity and serving as a scaffold to maintain electrode integrity.The conductivity of the network was further augmented by introducing P-doping at the optimum doping temperature of 350℃.Unlike the local conductive sites formed by the mere mixing of silicon and conductive agents,the consecutive network can affirm the improvement of the conductivity at a macro level.Moreover,first-principle calculations further validated that the rapid diffusion of Li^(+)is attributed to the tailored electronic microstructure and charge rearrangement of the fiber.The prepared consecutive conductive Si@P-doped carbonized cotton fiber anode outperforms the inconsecutive Si@Graphite anode in both cycling performance(capacity retention of 1777.15 mAh g^(-1) vs.682.56 mAh g^(-1) after 150 cycles at 0.3 C)and rate performance(1244.24 mAh g^(-1) vs.370.28 mAh g^(-1) at 2.0 C).The findings of this study may open up new avenues for the development of globally interconnected conductive networks in Si-based anodes,thereby enabling the fabrication of high-performance LIBs.展开更多
The advent of the 5G era has stimulated the rapid development of high power electronics with dense integration.Three-dimensional(3D)thermally conductive networks,possessing high thermal and electrical conductivities a...The advent of the 5G era has stimulated the rapid development of high power electronics with dense integration.Three-dimensional(3D)thermally conductive networks,possessing high thermal and electrical conductivities and many different structures,are regarded as key materials to improve the performance of electronic devices.We provide a critical overview of carbonbased 3D thermally conductive networks,emphasizing their preparation-structure-property relationships and their applications in different scenarios.A detailed discussion of the microscopic principles of thermal conductivity is provided,which is crucial for increasing it.This is followed by an in-depth account of the construction of 3D networks using different carbon materials,such as graphene,carbon foam,and carbon nanotubes.Techniques for the assembly of two-dimensional graphene into 3D networks and their effects on thermal conductivity are emphasized.Finally,the existing challenges and future prospects for 3D carbon-based thermally conductive networks are discussed.展开更多
KTi_(2)(PO_(4))_(3)is a promising anode material for potassium storage,but suffers from low conductivity and difficult balance between high capacity and good structural stability.Herein,the Ti_(3)C_(2)T_(x)MXene is us...KTi_(2)(PO_(4))_(3)is a promising anode material for potassium storage,but suffers from low conductivity and difficult balance between high capacity and good structural stability.Herein,the Ti_(3)C_(2)T_(x)MXene is used as a multifunctional binder to fabricate the KTi_(2)(PO_(4))_(3)electrode by the traditional homogenizing-coating method.The MXene nanosheets,together with the conductive agent super P nanoparticles,construct a multiple conductive network for fast electron/ion transfer and high electrochemical kinet-ics.Moreover,the network ensures the structural stability of the KTi_(2)(PO_(4))_(3)electrode during the de-intercalation/intercalation of 4 K^(+)ions,which is beneficial for simultaneously achieving high capacity and good cycle performance.Therefore,the MXene-bonded KTi_(2)(PO_(4))_(3)electrode delivers a reversible capacity of 255.2 mAh/g at 50 mA/g,outstanding rate capability with 132.3 mAh/g at 2 A/g,and ex-cellent cycle performance with 151.6 mAh/g at 1 A/g after 2000 cycles.This work not only suggests a high-performance anode material for potassium-ion batteries,but also demonstrates that the MXene is a promising binder material for constructing conductive electrodes in rechargeable batteries.展开更多
Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability,grouting and seepage analysis of dam foundation.With the aim of reducing deviation between fracture network mode...Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability,grouting and seepage analysis of dam foundation.With the aim of reducing deviation between fracture network model and measured data,a 3-D fracture network dynamic modeling method based on error analysis was proposed.Firstly,errors of four fracture volume density estimation methods(proposed by ODA,KULATILAKE,MAULDON,and SONG)and that of four fracture size estimation methods(proposed by EINSTEIN,SONG and TONON)were respectively compared,and the optimal methods were determined.Additionally,error index representing the deviation between fracture network model and measured data was established with integrated use of fractal dimension and relative absolute error(RAE).On this basis,the downhill simplex method was used to build the dynamic modeling method,which takes the minimum of error index as objective function and dynamically adjusts the fracture density and size parameters to correct the error index.Finally,the 3-D fracture network model could be obtained which meets the requirements.The proposed method was applied for 3-D fractures simulation in Miao Wei hydropower project in China for feasibility verification and the error index reduced from 2.618 to 0.337.展开更多
With the increasing power density and integration of electronic devices,polymeric composites with high thermal conductivity(TC)are in urgent demand for solving heat accumulation issues.However,the direct introduction ...With the increasing power density and integration of electronic devices,polymeric composites with high thermal conductivity(TC)are in urgent demand for solving heat accumulation issues.However,the direct introduction of inorganic fillers into a polymer matrix at low filler content usually leads to low TC enhancement.In this work,an interconnected three-dimensional(3D)polysulfone/hexagonal boron nitride-carbon nanofiber(PSF/BN-CNF)skeleton was prepared via the salt templated method to address this issue.After embedding into the epoxy(EP),the EP/PSF/BN-CNF composite presents a high TC of 2.18 W m^(−1) K^(−1) at a low filler loading of 28.61 wt%,corresponding to a TC enhancement of 990%compared to the neat epoxy.The enhanced TC is mainly attributed to the fabricated 3D interconnected structure and the efficient synergistic effect of BN and CNF.In addition,the TC of the epoxy composites can be further increased to 2.85 W m^(−1) K^(−1) at the same filler loading through a post-heat treatment of the PSF/BN-CNF skeletons.After carbonization at 1500°C,the adhesive PSF was converted into carbonaceous layers,which could serve as a thermally conductive glue to connect the filler network,further decreasing the interfacial thermal resistance and promoting phonon transport.Besides,the good heat dissipation performance of the EP/C/BN-CNF composites was directly confirmed by thermal infrared imaging,indicating a bright and broad application in the thermal management of modern electronics and energy fields.展开更多
With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directi...With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directional entropic scale is used to measure the anisotropy of spatial order in different directions.Compared with the traditional connectivity indexes based on the statistics of fracture geometry,the directional entropic scale is capable to quantify the anisotropy of connectivity and hydraulic conductivity in heterogeneous 3D fracture networks.According to the numerical analysis of directional entrogram and fluid flow in a number of the 3D fracture networks,the hydraulic conductivities and entropic scales in different directions both increase with spatial order(i.e.,trace length decreasing and spacing increasing)and are independent of the dip angle.As a result,the nonlinear correlation between the hydraulic conductivities and entropic scales from different directions can be unified as quadratic polynomial function,which can shed light on the anisotropic effect of spatial order and global entropy on the heterogeneous hydraulic behaviors.展开更多
As one of the core components of a magnetic refrigerator,magnetic refrigeration materials are expected to have not only a considerable magnetocaloric effect but also excellent thermal conductivity.The poor thermal con...As one of the core components of a magnetic refrigerator,magnetic refrigeration materials are expected to have not only a considerable magnetocaloric effect but also excellent thermal conductivity.The poor thermal conductivity of many competitive oxide-based magnetic refrigerants,exemplified by EuTiO3-based compounds,acts as a major limitation to their practical application.Therefore,improving the thermal conductivity of magnetic refrigeration materials has become a research emphasis of magnetic refrigeration in recent years.In this work,a series of EuTiO_(3)(ETO)/Cu composites with different copper additives was prepared using a solid-phase reaction method by introducing appropriate amounts of copper powder.The influence of the introduction of copper on the phase composition,microstructure,thermal conductivity,and magnetocaloric effect of the composites was systematically investigated.Unexpectedly,the thermal conductivity of the composites is enhanced by up to 260%due to copper addition,accompanied by only a 5%decrease in magnetic entropy change and refrigerating capacity.Copper additive forms localized thermal conductive networks and promotes the densification process,resulting in significantly enhanced thermal conductivity of the composites.This work demonstrates the feasibility of improving the thermal conductivity of oxide-base d magnetic refrigeration materials by introducing highly thermally conductive substances.展开更多
The probability model is used to analyze the fault tolerance of mesh. To simplify its analysis, it is as-sumed that the failure probability of each node is independent. A 3-D mesh is partitioned into smaller submeshes...The probability model is used to analyze the fault tolerance of mesh. To simplify its analysis, it is as-sumed that the failure probability of each node is independent. A 3-D mesh is partitioned into smaller submeshes,and then the probability with which each submesh satisfies the defined condition is computed. If each submesh satis-fies the condition, then the whole mesh is connected. Consequently, the probability that a 3-D mesh is connected iscomputed assuming each node has a failure probability. Mathematical methods are used to derive a relationship be-tween network node failure probability and network connectivity probability. The calculated results show that the 3-D mesh networks can remain connected with very high probability in practice. It is formally proved that when thenetwork node failure probability is boutded by 0.45 %, the 3-D mesh networks of more than three hundred thousandnodes remain connected with probability larger than 99 %. The theoretical results show that the method is a power-ful technique to calculate the lower bound of the connectivity probability of mesh networks.展开更多
Synthesizing multi-component composites via a straightforward,reliable,and scalable approach has been challenging.Herein,a three-dimensional nitrogen-doped porous carbon decorated with core-shell Ni_(3)Sn_(2)@carbon p...Synthesizing multi-component composites via a straightforward,reliable,and scalable approach has been challenging.Herein,a three-dimensional nitrogen-doped porous carbon decorated with core-shell Ni_(3)Sn_(2)@carbon particles(3D N-PC/Ni_(3)Sn_(2)@C)was customized through a simple salt-template pyrolysis approach.The formed Ni_(3)Sn_(2)particles are perfectly surrounded by crystalline carbon layers and em-bedded in 3D carbon walls during pyrolysis.The dual protection of crystalline carbon layers and porous carbon walls guarantees the electrical conductivity and stability of Ni_(3)Sn_(2).The intriguing 3D and core-shell structure coupled with the introduction of multiple components empowers the composite with rich heterogeneous interface and conductive network,and contributes to the lightweight,corrosion resistance,oxidation resistance,and superior stability of electromagnetic(EM)wave absorbers.The N-PC/Ni_(3)Sn_(2)@C possesses the minimum reflection loss(RL min)of-54.01 dB and wide effective absorption bandwidth(EAB)of 7.36 GHz under a low filler content of less than 10%.The concept in the work proposes a facile,eco-friendly,and scalable pathway for the synthesis of other heterogeneous structures of EM wave ab-sorbers.展开更多
Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is deter...Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly velocity zone exists in the western Sichuan plateau. The boundary between the positive and negative anomaly zones is the Longmenshan fault zone. The images of lower crust and upper mantle in the Longmenshan fault, Xianshuihe fault, Honghe fault and others show the characteristic of tectonic boundary, indicating that the faults likely penetrate the Moho discontinuity. The negative velocity anomalies at the depth of 50 km in the Tengchong volcanic area and the Panxi tectonic zone appear to be associated with the temperature and composition variations in the upper mantle. The overall features of the crustal and the upper mantle structures in the SichuanYunnan region are the lower average velocity in both crust and uppermost mantle, the large crustal thickness variations, and the existence of high conductivity layer in the crust or/and upper mantle, and higher geothermal value. All these features are closely related to the collision between the India and the Asia plates. The crustal velocity in the SichuanYunnan rhombic block generally shows normal value or positive anomaly, while the negative anomaly exists in the area along the large strike-slip faults as the block boundary. It is conducive to the crustal block side-pressing out along the faults. In the major seismic zones, the seismicity is relative to the negative anomaly velocity. Most strong earthquakes occurred in the upper-mid crust with positive anomaly or normal velocity, where the negative anomaly zone generally exists below.展开更多
Mobility metrics of wireless networks such as link availability, number of neighboring nodes, link duration, link state, and link stability make it difficult to provide a node with quality of services guarantee. In pr...Mobility metrics of wireless networks such as link availability, number of neighboring nodes, link duration, link state, and link stability make it difficult to provide a node with quality of services guarantee. In previous research on Quality of Service (QoS) for cellular networks especially for handling handoff connections, the design was based on a flat 2D hexagon cells. However, in reality Base Station antenna coverage is in a 3D space and there exists a blind spot;the area which is just above and bellow the radiated antenna. In this paper we introduce the concept of Blind Spot (BS) in which there is no signals to initiate a call or accepting a handoff one. In BS, the signal power equal zero. Even if there is enough bandwidth to initiate or accept a handoff call, it will be blocked or dropped respectively. We present an implementation of Static Borrowing Scheme (SBS) and we extend the dynamic-rate based borrowing scheme [1] into 3-Dimentional structure and call it 3-Dimensional Dynamic Based Borrowing Scheme (3D DBBS). The proposed new technique for resource sharing is to ensure the continuity for both originating and handoff connections in 3-D cellular networks based on Dynamic-Based Borrowing Scheme (3D BBS). This technique aims to minimize the blocking probability of the originating calls by minimizing the dropping probability of the handoff requests and maximizing the channel utilization. The results revealed that 3D DBBS outperformed the static based schemes by 5% on average even when the blind spot of the base station antenna is taken into consideration. When moving to a 3D space, the results of the simulation showed the 3D DBBS outperformed the static scheme by 2% on average. As a result, considering nodes in a 3D space will have better QoS guarantee as the blocking and dropping probabilities are decreased. Thus, the bandwidth utilization is increased.展开更多
In recent years,3D object detection using neural radiance fields(NeRF)has advanced significantly,yet challenges remain in effectively utilising the density field.Current methods often treat NeRF as a geometry learning...In recent years,3D object detection using neural radiance fields(NeRF)has advanced significantly,yet challenges remain in effectively utilising the density field.Current methods often treat NeRF as a geometry learning tool or rely on volume rendering,neglecting the density field's potential and feature dependencies.To address this,we propose NeRF-C3D,a novel framework incorporating a multi-scale feature fusion module with channel attention(MFCA).MFCA leverages channel attention to model feature dependencies,dynamically adjusting channel weights during fusion to enhance important features and suppress redundancy.This optimises density field representation and improves feature discriminability.Experiments on 3D-FRONT,Hypersim,and ScanNet demonstrate NeRF-C3D's superior performance validating MFCA's effectiveness in capturing feature relationships and showcasing its innovation in NeRF-based 3D detection.展开更多
This paper describes a 2D/3D vision chip with integrated sensing and processing capabilities.The 2D/3D vision chip architecture includes a 2D/3D image sensor and a programmable visual processor.In this architecture,we...This paper describes a 2D/3D vision chip with integrated sensing and processing capabilities.The 2D/3D vision chip architecture includes a 2D/3D image sensor and a programmable visual processor.In this architecture,we design a novel on-chip processing flow with die-to-die image transmission and low-latency fixed-point image processing.The vision chip achieves real-time end-to-end processing of convolutional neural networks(CNNs)and conventional image processing algo-rithms.Furthermore,an end-to-end 2D/3D vision system is built to exhibit the capacity of the vision chip.The vision system achieves real-timing applications under 2D and 3D scenes,such as human face detection(processing delay 10.2 ms)and depth map reconstruction(processing delay 4.1 ms).The frame rate of image acquisition,image process,and result display is larger than 30 fps.展开更多
Composite solid electrolytes hold the promise of merging complementary merits of solid polymer electrolytes and ceramic fillers to achieve solid batteries with comprehensive performance.Especially,three-dimensional in...Composite solid electrolytes hold the promise of merging complementary merits of solid polymer electrolytes and ceramic fillers to achieve solid batteries with comprehensive performance.Especially,three-dimensional inorganic electrolyte frameworks,such as Li_(7)La_(3)Zr_(2)O_(12),with fast and continuous lithium ion migration channels demonstrate great promise in composite solid electrolytes.Nevertheless,brittle ceramic conductor skeletons are incapable of providing sufficient mechanical adaptability,which restricts their practical application.Herein,a flexible,ion-conducting network which integrates Li_(7)La_(3)Zr_(2)O_(12)nanoparticles in polyacrylonitrile nanofibers is fabricated through electrospinning method.Subsequently,a composite electrolyte with three-dimensional continuous structure is achieved via in situ polymerizing of 1,3-dioxolane within the ionic conduction framework.The highly conductive Li7La3Zr2O12 reinforced polymer nanofibers are not only available to promote transportation of lithium ion,but also provide structural flexibility and mechanical robustness for composite electrolyte.Accordingly,the obtained composite electrolyte combines enhanced room temperature ionic conductivity(4.38×10^(-4)S·cm^(-1))with structural flexibility and mechanical robustness,supported by exceptional interfacial compatibility with lithium metal,enabling ultra-stable lithium symmetric battery operation(3000 h at 0.1 mA·cm^(-2)).Furthermore,as-prepared LiFePO_(4)and LiCoO_(2)/lithium solid-state batteries deliver high capacity retention of 96%after 350 cycles and capacity retention of 82%after 600 cycles at room temperature.This work provides a new avenue in design of advancing composite solid electrolytes.展开更多
The Tetrahedral Network(TEN) is a powerful 3-D vector structure in GIS, which has a lot of advantages such as simple structure, fast topological relation processing and rapid visualization. The difficulty of TEN appli...The Tetrahedral Network(TEN) is a powerful 3-D vector structure in GIS, which has a lot of advantages such as simple structure, fast topological relation processing and rapid visualization. The difficulty of TEN application is automatic creating data structure. Although a raster algorithm has been introduced by some authors, the problems in accuracy, memory requirement, speed and integrity are still existent. In this paper, the raster algorithm is completed and a vector algorithm is presented after a 3-D data model and structure of TEN have been introducted. Finally, experiment, conclusion and future work are discussed.展开更多
High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the norma...High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.展开更多
A novel manganese（H） coordination polymer [Mn（pdc）]n （pdc = pyridine-2,4- dicarboxylate） has been synthesized under hydrothermal conditions. The crystal is of monoclinic, space group P211n with a = 6.506（4）, b...A novel manganese（H） coordination polymer [Mn（pdc）]n （pdc = pyridine-2,4- dicarboxylate） has been synthesized under hydrothermal conditions. The crystal is of monoclinic, space group P211n with a = 6.506（4）, b = 9.392（6）, c = 11.217（7） A, β = 105.650（12）°, V= 660.0（7）A3, Z = 4, Mr = 220.04, Dc = 2.215 g/cm3,μ = 1.971 mm-1, F（000） = 436, Rint = 0.0345, R = 0.0360 and wR = 0.0778 for 1259 observed reflections with I 〉 2σ（I）. In the structure, the Mn（Ⅱ） atom is coordinated in a distorted octahedral arrangement by one pyridine N and five carboxylate O atoms from five pdc ligands, each of which coordinates to five Mn atoms to propagate a three-dimensional layered framework.展开更多
Currently,the practical application of SiO_(x) still has a huge hindrance in the area of lithium ion battery,because it is unable to achieve an effective contact with surrounding conducting materials,resulting in fail...Currently,the practical application of SiO_(x) still has a huge hindrance in the area of lithium ion battery,because it is unable to achieve an effective contact with surrounding conducting materials,resulting in failure to form lithium ion migration tunnels.In this work,we presented a facile method to synthesize the B-doped SiOx composite by adhering SiO_(x) particles with MWCNT(multi-walled carbon nanotube)under the assistance of lithium metaborate(LiBO_(2)).LiBO_(2),as a sintering aid,not only can react with SiO_(x) to form a compacted framework,but also build a three-dimensional(3D)conductive network for ions transportation.Furthermore,B-SiO_(x)@CNT@LBO anode delivers a remarkable lithium storage performance in terms of long cycles and high rate capability.A full cell coupled with NCM622 cathode achieves a high energy density of 429.5 Wh kg^(-1) based on the total mass of cathode.展开更多
基金supported by the National Natural Science Foundation of China(No.12205252)the Basic Public Welfare Re-search Special Project of Zhejiang Province(No.LZY22B040001)+4 种基金the Quzhou Science and Technology Plan Project(No.2022K39)Science and Technology Project of Quzhou Research Institute,Zhejiang University(Nos.IZQ2021KJ2032,IZQ2022KJ3014,and IZQ2022KJ3002)Independent scientific Research Project of Quzhou Research Institute,Zhejiang University(No.IZQ2021RCZX007)New“115 talents”Project ofQuzhou,National Nature Science Foundation of China(No.52172244)Fundamental Research Funds for the Central University(No.226202200053).
文摘The inferior conductivity and drastic volume expansion of silicon still remain the bottleneck in achieving high energy density Lithium-ion Batteries(LIBs).The design of the three-dimensional structure of electrodes by compositing silicon and carbon materials has been employed to tackle the above challenges,however,the exorbitant costs and the uncertainty of the conductive structure persist,leaving ample room for improvement.Herein,silicon nanoparticles were innovatively composited with eco-friendly biochar sourced from cotton to fabricate a 3D globally consecutive conductive network.The network serves a dual purpose:enhancing overall electrode conductivity and serving as a scaffold to maintain electrode integrity.The conductivity of the network was further augmented by introducing P-doping at the optimum doping temperature of 350℃.Unlike the local conductive sites formed by the mere mixing of silicon and conductive agents,the consecutive network can affirm the improvement of the conductivity at a macro level.Moreover,first-principle calculations further validated that the rapid diffusion of Li^(+)is attributed to the tailored electronic microstructure and charge rearrangement of the fiber.The prepared consecutive conductive Si@P-doped carbonized cotton fiber anode outperforms the inconsecutive Si@Graphite anode in both cycling performance(capacity retention of 1777.15 mAh g^(-1) vs.682.56 mAh g^(-1) after 150 cycles at 0.3 C)and rate performance(1244.24 mAh g^(-1) vs.370.28 mAh g^(-1) at 2.0 C).The findings of this study may open up new avenues for the development of globally interconnected conductive networks in Si-based anodes,thereby enabling the fabrication of high-performance LIBs.
文摘The advent of the 5G era has stimulated the rapid development of high power electronics with dense integration.Three-dimensional(3D)thermally conductive networks,possessing high thermal and electrical conductivities and many different structures,are regarded as key materials to improve the performance of electronic devices.We provide a critical overview of carbonbased 3D thermally conductive networks,emphasizing their preparation-structure-property relationships and their applications in different scenarios.A detailed discussion of the microscopic principles of thermal conductivity is provided,which is crucial for increasing it.This is followed by an in-depth account of the construction of 3D networks using different carbon materials,such as graphene,carbon foam,and carbon nanotubes.Techniques for the assembly of two-dimensional graphene into 3D networks and their effects on thermal conductivity are emphasized.Finally,the existing challenges and future prospects for 3D carbon-based thermally conductive networks are discussed.
基金support by National Natural Science Foundation of China(No.U2004212).
文摘KTi_(2)(PO_(4))_(3)is a promising anode material for potassium storage,but suffers from low conductivity and difficult balance between high capacity and good structural stability.Herein,the Ti_(3)C_(2)T_(x)MXene is used as a multifunctional binder to fabricate the KTi_(2)(PO_(4))_(3)electrode by the traditional homogenizing-coating method.The MXene nanosheets,together with the conductive agent super P nanoparticles,construct a multiple conductive network for fast electron/ion transfer and high electrochemical kinet-ics.Moreover,the network ensures the structural stability of the KTi_(2)(PO_(4))_(3)electrode during the de-intercalation/intercalation of 4 K^(+)ions,which is beneficial for simultaneously achieving high capacity and good cycle performance.Therefore,the MXene-bonded KTi_(2)(PO_(4))_(3)electrode delivers a reversible capacity of 255.2 mAh/g at 50 mA/g,outstanding rate capability with 132.3 mAh/g at 2 A/g,and ex-cellent cycle performance with 151.6 mAh/g at 1 A/g after 2000 cycles.This work not only suggests a high-performance anode material for potassium-ion batteries,but also demonstrates that the MXene is a promising binder material for constructing conductive electrodes in rechargeable batteries.
基金Project(51321065)supported by the Innovative Research Groups of the National Natural Science Foundation of ChinaProject(2013CB035904)supported by the National Basic Research Program of China(973 Program)Project(51439005)supported by the National Natural Science Foundation of China
文摘Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability,grouting and seepage analysis of dam foundation.With the aim of reducing deviation between fracture network model and measured data,a 3-D fracture network dynamic modeling method based on error analysis was proposed.Firstly,errors of four fracture volume density estimation methods(proposed by ODA,KULATILAKE,MAULDON,and SONG)and that of four fracture size estimation methods(proposed by EINSTEIN,SONG and TONON)were respectively compared,and the optimal methods were determined.Additionally,error index representing the deviation between fracture network model and measured data was established with integrated use of fractal dimension and relative absolute error(RAE).On this basis,the downhill simplex method was used to build the dynamic modeling method,which takes the minimum of error index as objective function and dynamically adjusts the fracture density and size parameters to correct the error index.Finally,the 3-D fracture network model could be obtained which meets the requirements.The proposed method was applied for 3-D fractures simulation in Miao Wei hydropower project in China for feasibility verification and the error index reduced from 2.618 to 0.337.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(No.51925403)the Major Research Plan of the National Natural Science Foundation of China(No.91934302)+1 种基金the National Natural Science Foundation of China(Nos.21676052,21606042)the Funding for Exploratory Projects of the National Key Laboratory of Chemical Engineering(SKL-ChE-20T07).
文摘With the increasing power density and integration of electronic devices,polymeric composites with high thermal conductivity(TC)are in urgent demand for solving heat accumulation issues.However,the direct introduction of inorganic fillers into a polymer matrix at low filler content usually leads to low TC enhancement.In this work,an interconnected three-dimensional(3D)polysulfone/hexagonal boron nitride-carbon nanofiber(PSF/BN-CNF)skeleton was prepared via the salt templated method to address this issue.After embedding into the epoxy(EP),the EP/PSF/BN-CNF composite presents a high TC of 2.18 W m^(−1) K^(−1) at a low filler loading of 28.61 wt%,corresponding to a TC enhancement of 990%compared to the neat epoxy.The enhanced TC is mainly attributed to the fabricated 3D interconnected structure and the efficient synergistic effect of BN and CNF.In addition,the TC of the epoxy composites can be further increased to 2.85 W m^(−1) K^(−1) at the same filler loading through a post-heat treatment of the PSF/BN-CNF skeletons.After carbonization at 1500°C,the adhesive PSF was converted into carbonaceous layers,which could serve as a thermally conductive glue to connect the filler network,further decreasing the interfacial thermal resistance and promoting phonon transport.Besides,the good heat dissipation performance of the EP/C/BN-CNF composites was directly confirmed by thermal infrared imaging,indicating a bright and broad application in the thermal management of modern electronics and energy fields.
基金supported by the National Natural Science Foundation of China(Nos.42077243,52209148,and 52079062).
文摘With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directional entropic scale is used to measure the anisotropy of spatial order in different directions.Compared with the traditional connectivity indexes based on the statistics of fracture geometry,the directional entropic scale is capable to quantify the anisotropy of connectivity and hydraulic conductivity in heterogeneous 3D fracture networks.According to the numerical analysis of directional entrogram and fluid flow in a number of the 3D fracture networks,the hydraulic conductivities and entropic scales in different directions both increase with spatial order(i.e.,trace length decreasing and spacing increasing)and are independent of the dip angle.As a result,the nonlinear correlation between the hydraulic conductivities and entropic scales from different directions can be unified as quadratic polynomial function,which can shed light on the anisotropic effect of spatial order and global entropy on the heterogeneous hydraulic behaviors.
基金Project supported by the National Key R&D Program of China(2021YFB3501204)the National Science Fund for Distinguished Young Scholars(51925605)+1 种基金the National Science Foundation for Excellent Young Scholars(52222107)the National Natural Science Foundation of China(52171195,52201036)。
文摘As one of the core components of a magnetic refrigerator,magnetic refrigeration materials are expected to have not only a considerable magnetocaloric effect but also excellent thermal conductivity.The poor thermal conductivity of many competitive oxide-based magnetic refrigerants,exemplified by EuTiO3-based compounds,acts as a major limitation to their practical application.Therefore,improving the thermal conductivity of magnetic refrigeration materials has become a research emphasis of magnetic refrigeration in recent years.In this work,a series of EuTiO_(3)(ETO)/Cu composites with different copper additives was prepared using a solid-phase reaction method by introducing appropriate amounts of copper powder.The influence of the introduction of copper on the phase composition,microstructure,thermal conductivity,and magnetocaloric effect of the composites was systematically investigated.Unexpectedly,the thermal conductivity of the composites is enhanced by up to 260%due to copper addition,accompanied by only a 5%decrease in magnetic entropy change and refrigerating capacity.Copper additive forms localized thermal conductive networks and promotes the densification process,resulting in significantly enhanced thermal conductivity of the composites.This work demonstrates the feasibility of improving the thermal conductivity of oxide-base d magnetic refrigeration materials by introducing highly thermally conductive substances.
基金Project (69928201) supported by the National Science Fund for Distinguished Young Scholars+1 种基金project (90104028) by the National Natural Science Foundation of China Project by Changjiang Scholar Re-ward Project
文摘The probability model is used to analyze the fault tolerance of mesh. To simplify its analysis, it is as-sumed that the failure probability of each node is independent. A 3-D mesh is partitioned into smaller submeshes,and then the probability with which each submesh satisfies the defined condition is computed. If each submesh satis-fies the condition, then the whole mesh is connected. Consequently, the probability that a 3-D mesh is connected iscomputed assuming each node has a failure probability. Mathematical methods are used to derive a relationship be-tween network node failure probability and network connectivity probability. The calculated results show that the 3-D mesh networks can remain connected with very high probability in practice. It is formally proved that when thenetwork node failure probability is boutded by 0.45 %, the 3-D mesh networks of more than three hundred thousandnodes remain connected with probability larger than 99 %. The theoretical results show that the method is a power-ful technique to calculate the lower bound of the connectivity probability of mesh networks.
基金financially supported by the Natural Science Foundation of Shandong Province(No.ZR2019YQ24)the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites).
文摘Synthesizing multi-component composites via a straightforward,reliable,and scalable approach has been challenging.Herein,a three-dimensional nitrogen-doped porous carbon decorated with core-shell Ni_(3)Sn_(2)@carbon particles(3D N-PC/Ni_(3)Sn_(2)@C)was customized through a simple salt-template pyrolysis approach.The formed Ni_(3)Sn_(2)particles are perfectly surrounded by crystalline carbon layers and em-bedded in 3D carbon walls during pyrolysis.The dual protection of crystalline carbon layers and porous carbon walls guarantees the electrical conductivity and stability of Ni_(3)Sn_(2).The intriguing 3D and core-shell structure coupled with the introduction of multiple components empowers the composite with rich heterogeneous interface and conductive network,and contributes to the lightweight,corrosion resistance,oxidation resistance,and superior stability of electromagnetic(EM)wave absorbers.The N-PC/Ni_(3)Sn_(2)@C possesses the minimum reflection loss(RL min)of-54.01 dB and wide effective absorption bandwidth(EAB)of 7.36 GHz under a low filler content of less than 10%.The concept in the work proposes a facile,eco-friendly,and scalable pathway for the synthesis of other heterogeneous structures of EM wave ab-sorbers.
基金Foundation item: National Scientific and Technological Development Program (95-973-02-02) the Climb Program (95-S-05-01) of National Scientific and Technological Ministry of China and the State Natural Sciences Foundation of China (49874021).
文摘Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly velocity zone exists in the western Sichuan plateau. The boundary between the positive and negative anomaly zones is the Longmenshan fault zone. The images of lower crust and upper mantle in the Longmenshan fault, Xianshuihe fault, Honghe fault and others show the characteristic of tectonic boundary, indicating that the faults likely penetrate the Moho discontinuity. The negative velocity anomalies at the depth of 50 km in the Tengchong volcanic area and the Panxi tectonic zone appear to be associated with the temperature and composition variations in the upper mantle. The overall features of the crustal and the upper mantle structures in the SichuanYunnan region are the lower average velocity in both crust and uppermost mantle, the large crustal thickness variations, and the existence of high conductivity layer in the crust or/and upper mantle, and higher geothermal value. All these features are closely related to the collision between the India and the Asia plates. The crustal velocity in the SichuanYunnan rhombic block generally shows normal value or positive anomaly, while the negative anomaly exists in the area along the large strike-slip faults as the block boundary. It is conducive to the crustal block side-pressing out along the faults. In the major seismic zones, the seismicity is relative to the negative anomaly velocity. Most strong earthquakes occurred in the upper-mid crust with positive anomaly or normal velocity, where the negative anomaly zone generally exists below.
文摘Mobility metrics of wireless networks such as link availability, number of neighboring nodes, link duration, link state, and link stability make it difficult to provide a node with quality of services guarantee. In previous research on Quality of Service (QoS) for cellular networks especially for handling handoff connections, the design was based on a flat 2D hexagon cells. However, in reality Base Station antenna coverage is in a 3D space and there exists a blind spot;the area which is just above and bellow the radiated antenna. In this paper we introduce the concept of Blind Spot (BS) in which there is no signals to initiate a call or accepting a handoff one. In BS, the signal power equal zero. Even if there is enough bandwidth to initiate or accept a handoff call, it will be blocked or dropped respectively. We present an implementation of Static Borrowing Scheme (SBS) and we extend the dynamic-rate based borrowing scheme [1] into 3-Dimentional structure and call it 3-Dimensional Dynamic Based Borrowing Scheme (3D DBBS). The proposed new technique for resource sharing is to ensure the continuity for both originating and handoff connections in 3-D cellular networks based on Dynamic-Based Borrowing Scheme (3D BBS). This technique aims to minimize the blocking probability of the originating calls by minimizing the dropping probability of the handoff requests and maximizing the channel utilization. The results revealed that 3D DBBS outperformed the static based schemes by 5% on average even when the blind spot of the base station antenna is taken into consideration. When moving to a 3D space, the results of the simulation showed the 3D DBBS outperformed the static scheme by 2% on average. As a result, considering nodes in a 3D space will have better QoS guarantee as the blocking and dropping probabilities are decreased. Thus, the bandwidth utilization is increased.
基金funded by the Qiyuan Innovation Foundation(Grant S20210201067)sub‐themes(No.9072323404).
文摘In recent years,3D object detection using neural radiance fields(NeRF)has advanced significantly,yet challenges remain in effectively utilising the density field.Current methods often treat NeRF as a geometry learning tool or rely on volume rendering,neglecting the density field's potential and feature dependencies.To address this,we propose NeRF-C3D,a novel framework incorporating a multi-scale feature fusion module with channel attention(MFCA).MFCA leverages channel attention to model feature dependencies,dynamically adjusting channel weights during fusion to enhance important features and suppress redundancy.This optimises density field representation and improves feature discriminability.Experiments on 3D-FRONT,Hypersim,and ScanNet demonstrate NeRF-C3D's superior performance validating MFCA's effectiveness in capturing feature relationships and showcasing its innovation in NeRF-based 3D detection.
基金supported in part by the National Key Research and Development Program of China(Grant No.2019YFB2204300)in part by the National Natural Science Foundation of China(Grant Nos.62334008 and 62274154)in part by the Key Program of National Natural Science Foundation of China(Grant No.62134004).
文摘This paper describes a 2D/3D vision chip with integrated sensing and processing capabilities.The 2D/3D vision chip architecture includes a 2D/3D image sensor and a programmable visual processor.In this architecture,we design a novel on-chip processing flow with die-to-die image transmission and low-latency fixed-point image processing.The vision chip achieves real-time end-to-end processing of convolutional neural networks(CNNs)and conventional image processing algo-rithms.Furthermore,an end-to-end 2D/3D vision system is built to exhibit the capacity of the vision chip.The vision system achieves real-timing applications under 2D and 3D scenes,such as human face detection(processing delay 10.2 ms)and depth map reconstruction(processing delay 4.1 ms).The frame rate of image acquisition,image process,and result display is larger than 30 fps.
基金National Key Research and Development Program of China(No.2019YFA0705700)the National Natural Science Foundation of China(No.52472186)。
文摘Composite solid electrolytes hold the promise of merging complementary merits of solid polymer electrolytes and ceramic fillers to achieve solid batteries with comprehensive performance.Especially,three-dimensional inorganic electrolyte frameworks,such as Li_(7)La_(3)Zr_(2)O_(12),with fast and continuous lithium ion migration channels demonstrate great promise in composite solid electrolytes.Nevertheless,brittle ceramic conductor skeletons are incapable of providing sufficient mechanical adaptability,which restricts their practical application.Herein,a flexible,ion-conducting network which integrates Li_(7)La_(3)Zr_(2)O_(12)nanoparticles in polyacrylonitrile nanofibers is fabricated through electrospinning method.Subsequently,a composite electrolyte with three-dimensional continuous structure is achieved via in situ polymerizing of 1,3-dioxolane within the ionic conduction framework.The highly conductive Li7La3Zr2O12 reinforced polymer nanofibers are not only available to promote transportation of lithium ion,but also provide structural flexibility and mechanical robustness for composite electrolyte.Accordingly,the obtained composite electrolyte combines enhanced room temperature ionic conductivity(4.38×10^(-4)S·cm^(-1))with structural flexibility and mechanical robustness,supported by exceptional interfacial compatibility with lithium metal,enabling ultra-stable lithium symmetric battery operation(3000 h at 0.1 mA·cm^(-2)).Furthermore,as-prepared LiFePO_(4)and LiCoO_(2)/lithium solid-state batteries deliver high capacity retention of 96%after 350 cycles and capacity retention of 82%after 600 cycles at room temperature.This work provides a new avenue in design of advancing composite solid electrolytes.
基金Project supported by the National Natural Science Foundation of China (No.69833010)
文摘The Tetrahedral Network(TEN) is a powerful 3-D vector structure in GIS, which has a lot of advantages such as simple structure, fast topological relation processing and rapid visualization. The difficulty of TEN application is automatic creating data structure. Although a raster algorithm has been introduced by some authors, the problems in accuracy, memory requirement, speed and integrity are still existent. In this paper, the raster algorithm is completed and a vector algorithm is presented after a 3-D data model and structure of TEN have been introducted. Finally, experiment, conclusion and future work are discussed.
基金Foundation of National Natural Science Foundation of China,Grant/Award Number:51903145Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China,Grant/Award Number:2019JC-11Wang L.would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,Grant/Award Number:CX202053。
文摘High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.
基金This project was supported by the NNSFC (No. 20471061)the Science & Technology Innovation Foundation for the Young Scholar of Fujian Province (No. 2005J059)
文摘A novel manganese（H） coordination polymer [Mn（pdc）]n （pdc = pyridine-2,4- dicarboxylate） has been synthesized under hydrothermal conditions. The crystal is of monoclinic, space group P211n with a = 6.506（4）, b = 9.392（6）, c = 11.217（7） A, β = 105.650（12）°, V= 660.0（7）A3, Z = 4, Mr = 220.04, Dc = 2.215 g/cm3,μ = 1.971 mm-1, F（000） = 436, Rint = 0.0345, R = 0.0360 and wR = 0.0778 for 1259 observed reflections with I 〉 2σ（I）. In the structure, the Mn（Ⅱ） atom is coordinated in a distorted octahedral arrangement by one pyridine N and five carboxylate O atoms from five pdc ligands, each of which coordinates to five Mn atoms to propagate a three-dimensional layered framework.
基金sponsored by the National Natural Science Foundation of China(21875107,U1802256,51672128,52072173 and 21773118)Jiangsu Specially-Appointed Professors Program,Jiangsu Province Outstanding Youth Fund(SBK2020010215)+4 种基金Leading Edge Technology of Jiangsu Province(BK20202008)Key Research and Development Program in Jiangsu Province(BE2018122)Natural Science Foundation of Jiangsu Province(BK20170778)Fundamental Research Funds for the Central Universities(NE2016005)and the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)W.H.acknowledges support from Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX20_0192).
文摘Currently,the practical application of SiO_(x) still has a huge hindrance in the area of lithium ion battery,because it is unable to achieve an effective contact with surrounding conducting materials,resulting in failure to form lithium ion migration tunnels.In this work,we presented a facile method to synthesize the B-doped SiOx composite by adhering SiO_(x) particles with MWCNT(multi-walled carbon nanotube)under the assistance of lithium metaborate(LiBO_(2)).LiBO_(2),as a sintering aid,not only can react with SiO_(x) to form a compacted framework,but also build a three-dimensional(3D)conductive network for ions transportation.Furthermore,B-SiO_(x)@CNT@LBO anode delivers a remarkable lithium storage performance in terms of long cycles and high rate capability.A full cell coupled with NCM622 cathode achieves a high energy density of 429.5 Wh kg^(-1) based on the total mass of cathode.
