Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation o...Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation of intelligent ships,route planning technologies have developed many route planning algorithms that prioritize economy and safety.This paper conducts an in-depth study of algorithm efficiency for a route planning problem,proposing an intelligent ship route planning algorithm based on the adaptive step size Informed-RRT^(*).This algorithm can quickly plan a short route according to automatic obstacle avoidance and is suitable for planning the routes of intelligent ships.Results show that the adaptive step size Informed-RRT^(*) algorithm can shorten the optimal route length by approximately 13.05%while ensuring the running time of the planning algorithm and avoiding approximately 23.64%of redundant sampling nodes.The improved algorithm effectively circumvents unnecessary calculations and reduces a large amount of redundant sampling data,thus improving the efficiency of route planning.In a complex water environment,the unique adaptive step size mechanism enables this algorithm to prevent restricted search tree expansion,showing strong search ability and robustness,which is of practical significance for the development of intelligent ships.展开更多
An improved version of the sparse A^(*)algorithm is proposed to address the common issue of excessive expansion of nodes and failure to consider current ship status and parameters in traditional path planning algorith...An improved version of the sparse A^(*)algorithm is proposed to address the common issue of excessive expansion of nodes and failure to consider current ship status and parameters in traditional path planning algorithms.This algorithm considers factors such as initial position and orientation of the ship,safety range,and ship draft to determine the optimal obstacle-avoiding route from the current to the destination point for ship planning.A coordinate transformation algorithm is also applied to convert commonly used latitude and longitude coordinates of ship travel paths to easily utilized and analyzed Cartesian coordinates.The algorithm incorporates a hierarchical chart processing algorithm to handle multilayered chart data.Furthermore,the algorithm considers the impact of ship length on grid size and density when implementing chart gridification,adjusting the grid size and density accordingly based on ship length.Simulation results show that compared to traditional path planning algorithms,the sparse A^(*)algorithm reduces the average number of path points by 25%,decreases the average maximum storage node number by 17%,and raises the average path turning angle by approximately 10°,effectively improving the safety of ship planning paths.展开更多
In recent years,graphene-based composite films have been greatly developed in the field of electromagnetic shielding interference(EMI).However,it is still a huge challenge to prepare graphene-based composite films wit...In recent years,graphene-based composite films have been greatly developed in the field of electromagnetic shielding interference(EMI).However,it is still a huge challenge to prepare graphene-based composite films with excellent mechanical properties,conductivity and electromagnetic shielding properties.In this work,we adopted a facile and effective method by annealing the alkali-treated polyacrylonitrile(aPAN)nanofibers reinforced graphene oxide(GO)composite films at 2000°C to obtain graphene-carbon nanofibers composite films(GCFs).Microscopically,carbon nanofibers(CNFs)were intercalated into the graphene sheets,and microgasbags structure was formed during the heat treatment process.The special structure makes GCFs have superior tensile strength(10.4 MPa)at 5%strain.After repeated folding over1000 times,the films still demonstrate excellent structural integrity and flexibility performance.Interestingly,the graphene-based composite films with 10 wt%a PAN nanofibers exhibit an extremely low density of about 0.678 g/cm^(3)and excellent electrical conductivity of 1.72×10^(5)S/m.Further,an outstanding electromagnetic shielding effectiveness(SE)of 55–57 d B was achieved,and the corresponding value of the specific SE/thickness can reach 67,601–70,059 d B·cm^(2)/g,which is the highest among reported graphenebased shielding materials.The significant electromagnetic shielding performance is due to the synergistic enhancement effect brought by the excellent conductivity of carbon nanofibers and graphene,the formed effective conductive network and the microgasbags structure.Electromagnetism simulation further clarified that the underlying mechanism should be mainly attributed to the conduction loss and multiple reflections caused by the special structure of GCFs.This work will provide new solutions for low density,high flexibility and excellent electromagnetic shielding properties materials in the next generation of foldable and wearable electronics.展开更多
Although lightweight and three-dimensional(3 D) graphene aerogels are highly desirable for microwave absorption(MA) due to their high porosity,specific surface area,and 3 D conductive network,it still remains a large ...Although lightweight and three-dimensional(3 D) graphene aerogels are highly desirable for microwave absorption(MA) due to their high porosity,specific surface area,and 3 D conductive network,it still remains a large challenge to construct a multifunctional application framework to quickly adapt to the complex practical environment,making it to be efficiently applied in a variety of complex situation.Herein,multifunctional aramid nanofibers(ANFs) reinforced reduced graphene oxide aerogels(RGO@ANF) have been achieved by in-situ gel reaction,freeze-drying,and thermal annealing processes.The introduced ANFs in RGO aerogels can prevent the graphene sheets from over-stacking and enhance the connectivity of cell walls,thus leading to excellent compression resistance,MA,sound absorption,and thermal insulation performance.Under 70% strain,the maximum compressive stress of RGO@ANF aerogel reaches78.8 kPa,and reversible compressibility with reliable resistance to fatigue for 100 compressive cycles at20% strain.Further,the RGO@ANF aerogel exhibit a minimum reflection loss(RL_(min)) of-56.5 dB and a maximum effective absorption bandwidth(EAB) of 7.0 GHz at a thickness of 2.8 mm,basically covering the X and Ku bands.Moreover,the hybrid aerogel exhibited excellent sound absorption with an average absorption coefficient> 0.56 at 2-6 kHz and good thermal insulation performance with low thermal conductivity of about 49.18 mW m-1K-1.The integrated graphene aerogels with such multifunctional performances hold a great promise for applications such as MA,sound absorption,and heat insulation.展开更多
Traditional materials discovery is in ‘trial-and-error’ mode, leading to the issues of low-efficiency, high-cost, and unsustainability in materials design. Meanwhile, numerous experimental and computational trials a...Traditional materials discovery is in ‘trial-and-error’ mode, leading to the issues of low-efficiency, high-cost, and unsustainability in materials design. Meanwhile, numerous experimental and computational trials accumulate enormous quantities of data with multi-dimensionality and complexity, which might bury critical ‘structure–properties’ rules yet unfortunately not well explored. Machine learning(ML), as a burgeoning approach in materials science, may dig out the hidden structure–properties relationship from materials bigdata, therefore, has recently garnered much attention in materials science. In this review, we try to shortly summarize recent research progress in this field, following the ML paradigm:(i) data acquisition →(ii) feature engineering →(iii) algorithm →(iv) ML model →(v) model evaluation →(vi) application. In section of application, we summarize recent work by following the ‘material science tetrahedron’:(i) structure and composition →(ii) property →(iii) synthesis →(iv) characterization, in order to reveal the quantitative structure–property relationship and provide inverse design countermeasures. In addition, the concurrent challenges encompassing data quality and quantity, model interpretability and generalizability, have also been discussed. This review intends to provide a preliminary overview of ML from basic algorithms to applications.展开更多
The movements and intentions of other ships can be determined by gathering and examining ship sound signals.The extraction and analysis of ship sound signals fundamentally support the autonomous navigation of intellig...The movements and intentions of other ships can be determined by gathering and examining ship sound signals.The extraction and analysis of ship sound signals fundamentally support the autonomous navigation of intelligent ships.Mel scale frequency cepstral coefficient(MFCC)feature parameters are improved and optimized to form NewMFCC by introducing second-order difference and wavelet packet decomposition transformation methods in this paper.Transforming sound signals into a feature vector that fully describes the dynamic characteristics of ship sound signals and the high-and low-frequency information solves the problem of the inability to transport ordinary sound signals directly as signals for training in machine learning models.Radial basis function kernels are used to conduct support vector machine classifier simulation experiments.Five types of sound signals,namely,one type of ship sound signals and four types of interference sound signals,are categorized and identified as classification targets to verify the feasibility of the classification of ship sound signals and interference signals.The proposed method improves classification accuracy by approximately 15%.展开更多
This paper deals with a series of novel processing techniques based on the in situ production of metal matrix composites (MMCs). In situ techniques involve a chemical reaction resulting in the formation of a very fine...This paper deals with a series of novel processing techniques based on the in situ production of metal matrix composites (MMCs). In situ techniques involve a chemical reaction resulting in the formation of a very fine and thermodynamically stable reinforcing ceramic phase within a metal matrix. As a result, this provides thermodynamic compatibility at the matrix-reinforcement interface. The reinforcement surfaces are also likely to be free of contamination and, therefore, a stronger matrix-dispersion bond can be achieved. Some of these technologies including DIMOX^? XD, PRIMEX^? reactive gas infiltration, high-temperature self-propagating synthesis (SHS), and liquid-solid, or solid-gas-liquid reactions as well as plasma in situ MMCs are expressed in this paper.展开更多
Fabrics,a class of carriers,have been pioneered in electromagnetic protection,but their microwave absorbing potential has not been fully explored for a considerable period.Herein,aramid nanofibers(ANFs)enhanced reduce...Fabrics,a class of carriers,have been pioneered in electromagnetic protection,but their microwave absorbing potential has not been fully explored for a considerable period.Herein,aramid nanofibers(ANFs)enhanced reduced graphene oxide fabrics(ANF/rGO fabrics)were synthesized by wet spinning-chemical reduction.The ANF/rGO fabrics can achieve the minimum reflection loss(RLmin)of−15.8 dB with a thickness of 2.7 mm.On this basis,ANF/rGO fabrics grown with polyaniline(ANF/rGO-PANi fabrics)through in-situ doping polymerization were obtained.Polyaniline compensates for the lack of conductivity of the dielectric fabrics,bringing higher impedance matching and attenuation capability.The corresponding RLmin can reach−52.3 dB under 2.9 mm and the effective absorption bandwidth(EAB)increases to 6 GHz covering the whole Ku band under 2.5 mm.The fabrics woven by high-strength graphene-based hybrid fibers proposed in this study provide a new angle to achieve high-efficiency microwave absorption.展开更多
Fabrics have attracted significant attention in the field of electromagnetic shielding due to their unique grid structure,high electrical conductivity,and flexibility.To enrich the research of textiles for microwave a...Fabrics have attracted significant attention in the field of electromagnetic shielding due to their unique grid structure,high electrical conductivity,and flexibility.To enrich the research of textiles for microwave absorption,two-dimensional transition metal carbide(MXene)-enhanced reduced graphene oxide-based fabrics(MXene/RGO fabrics)were synthesized in this paper by using wet spinning–ionic cross-linking–chemical reduction strategy.MXene/RGO fabrics achieve a minimum reflection loss of−58.3 dB at 17.6 GHz and a thickness of 2.4 mm,with an effective absorption bandwidth of 4.92 GHz.In addition,the combination of electromagnetic finite element simulation technology and test results was used to further elucidate the response mode and loss mechanism of MXene/RGO fabrics.The MXene/RGO composite fibers exhibit a tuned attenuation ability and impedance matching performance,which is attributed to the increased polarization relaxation loss caused by the large number of heterogeneous interfaces between RGO,MXene,and TiO2 particles,as well as the appropriate electrical conductivity(16.6 S/cm).MXene/RGO fibers exhibit excellent microwave absorption performance,mechanical strength(534 MPa),easy modification,and fatigue resistance,promising stable absorption of electromagnetic waves in complex environments,thereby expanding the application scenarios of fabrics in the field of microwave absorption.展开更多
Despite significant advancements in microwave absorption materials(MAMs)for electromagnetic interference mitigation,the integration of robust microwave absorption(MA)and corrosion resistance into a unified system rema...Despite significant advancements in microwave absorption materials(MAMs)for electromagnetic interference mitigation,the integration of robust microwave absorption(MA)and corrosion resistance into a unified system remains a critical challenge,particularly for long-term durability in harsh environments.Conventional approaches relying on multiphase composites often suffer from compromised functionality due to intrinsic property conflicts between absorption and anti-corrosion components.Here,we propose an integrated design strategy of active-passive corrosion inhibition and MA to design composite volatile corrosion inhibition coatings with synergistic dielectric attenuation and multiple corrosion protection effects.Dielectric property modulation strategy-based,we achieved precise modulation of permittivity gradients and interfacial polarization for RGO/FCIP@SiO_(2),resulting in optimal impedance matching and record-breaking MA performance:a minimal reflection loss(RL_(min))of-68 dB at 12.82 GHz with a 7 GHz effective absorption bandwidth(EAB)at 2.0 mm thickness.Moreover,the two-dimensional lamellar reduced graphene oxide(RGO)has a“maze effect”and superhydrophobic architecture(162.3°contact angle)to passively defend against corrosive media.Concurrently,the multicomponent volatile corrosion inhibitor(BGC)system endows the composite with exceptional active corrosion inhibition.Through the dynamic anti-corrosion process involving vapor-phase release,surface adsorption,and protective film formation of corrosion inhibitor molecules,this system significantly enhances corrosion protection.Remarkably,it maintains 99.36%corrosion inhibition efficiency after 360-hour salt spray exposure and 25 friction cycles,without MA performance degradation.展开更多
Recently,biomass-derived three-dimensional (3D) porous carbon materials have been gaining more interest as promising microwave absorbers due to their low cost,vast availability,and sustainability.Here,a novel 3D inter...Recently,biomass-derived three-dimensional (3D) porous carbon materials have been gaining more interest as promising microwave absorbers due to their low cost,vast availability,and sustainability.Here,a novel 3D interconnected porous magnetic carbon foams are in-situ synthesized via a combination of sol-gel and carbonization process with wheat straw as the carbon source and FeCl3·6H2O as the magnetic regulating agent.During the process of foams formation,the lignocelluloses from the steam-exploded wheat straw are converted into interconnected carbon sheet networks with hierarchical porous structures,and the precursor FeCl3·6H2O is converted into magnetic nanoparticles uniformly embedded in the porous carbon foams.The generated magnetic nanoparticles are benefit to enhance the interface polarization and magnetic loss ability to improve the efficient complementarities between the dielectric and magnetic loss,thus increasing the impedance matching.The obtained sample treated at 600 ℃ displays the best microwave absorption (MA) performance.It presents a minimal reflection loss (RL) of-43.6 dB at 7.1 GHz and the effective bandwidth (RL <-10 dB) is 3.3 GHz with the thickness of 4.7 mm.The 3D porous structure,multi-interfaces and the synergy of dielectric loss and magnetic loss make great contribution to the outstanding MA performance.展开更多
Despite recent progress in the synthesis and application of graphene-based aerogels, some challenges such as scalable and cost-effective production, and miniaturization still remain, which hinder the practical applica...Despite recent progress in the synthesis and application of graphene-based aerogels, some challenges such as scalable and cost-effective production, and miniaturization still remain, which hinder the practical application of these materials. Here we report a large-scale electrospinning method to generate graphene-based aerogel microspheres （AMs）, which show broadband, tunable and high-performance microwave absorption. Graphene/Fe3O4 AMs with a large number of openings with hierarchical connecting radial microcharmels can be obtained via electrospinning-freeze drying followed by calcination. Importantly, for a given Fe3O4：graphene mass ratio, altering the shape of aerogel monoliths or powders into aerogel microspheres leads to unique electromagnetic wave properties. As expected, the reflection loss of graphene/Fe3O4 AMs-1：1 with only 5 wt.% absorber loading reaches -51.5 dB at 9.2 GHz with a thickness of 4.0 mm and a broad absorption bandwidth （RL 〈-10 dB） of 6.5 GHz. Furthermore, switching to coaxial electrospinning enables the fabrication of SiO2 coatings to construct graphene/Fe3O4@SiO2 core-shell AMs. The coatings influence the electromagnetic wave absorption of graphene/Fe3O4 AMs significantly. In view of these advantages, we believe that this processing technique may be extended to fabricate a wide range of unique graphene-based architectures for functional design and applications.展开更多
Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-spe...Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-specific needs.Herein,we highlight graphene aerogel spheres with controllable hollow structures(HGAS)that are delicately designed and manufactured via coaxial electrospinning coupled with freeze-drying and calcination.The HGAS exhibit a spherical configuration at the macroscale,while the construction elements of graphene on the microscale showing an interconnected radial microchannel structure.Further ball-in-ball graphene aerogel spheres(BGAS)are obtained by reference to the triaxial electrospinning technology.The as-prepared spheres possess the controllable integrated conductive networks,leading to the effective dielectric loss and impedance matching thus bringing on high-performance microwave absorption.The as-obtained HGAS shows a minimum reflection loss of-52.7 dB and a broad effective absorption bandwidth(f)of 7.0 GHz with thickness of 2.3 mm.Further,the fe reaches 9.3 GHz for BGAS with thickness of 3.4 mm.Aforementioned superior microwave absorption of HGAS and BGAS confirms combination of multiaxial electrospinning and freeze-drying on the multiscale is an effective strategy for scalable fabrication of advanced microwave.absorbing functional graphene aerogel spheres.展开更多
In order to meet the requirements of the marine environment for microwave absorption(MA)materials,we put forward the strategy of constructing multi-functional composite materials,which integrate microwave absorption,a...In order to meet the requirements of the marine environment for microwave absorption(MA)materials,we put forward the strategy of constructing multi-functional composite materials,which integrate microwave absorption,anti-corrosion,and antibacterial properties.Herein,graphene oxide(GO)was used as a template to induce the growth of zeolitic imidazolate framework-8(ZIF-8),simultaneously as a two-dimensional(2D)nanocontainers to load corrosion inhibitors to achieve pH-responsive and self-healing properties.Finally,quaternary ammonium salt(dimethyl octadecyl(3-trimethoxylsilyl propyl)ammonium chloride(DMAOP))and sodium ascorbate(VCNa)were introduced to achieve synergistic antibacterial activity and the reduction of GO.The 2D strip-like structure of ZIF-8 was due to the confined growth induced by the electrostatic attraction between ZIF-8 and GO sheets.The as-obtained reduced GO(RGO)/ZIF-8/DMAOP5 exhibited excellent microwave absorption(MA)properties,with a minimum reflection loss(RL)value of-47.08 dB at 12.73 GHz when the thickness was 2.8 mm.Moreover,the effective absorption bandwidth reached 6.84 GHz.After soaking in 3.5%NaCl solution for 35 days,the RGO/ZIF-8/DMAOP5-0.7%coating still achieved an impedance value of 4.585×107Ω·cm^(2) and a protective efficiency of 99.994%,providing superior anti-corrosion properties.In addition,fantastic antibacterial activity was obtained,with the antibacterial rates of RGO/ZIF-8/DMAOP_(10) reaching 99.39%and 100%against Escherichia coli and Staphylococcus aureus.This work could open new avenues towards the development of a new generation of multifunctional MA materials.展开更多
Helical carbon nanotubes （HCNTs） are highly desirable due to their unique geometrical elegance and inherent physical properties; however, high-efficiency synthesis of high-purity HCNTs with high yield and full eluci...Helical carbon nanotubes （HCNTs） are highly desirable due to their unique geometrical elegance and inherent physical properties; however, high-efficiency synthesis of high-purity HCNTs with high yield and full elucidation of their growth mechanism remains challenging. Traditional methods to achieve the high-yield growth of HCNTs mainly focus on controlling the size of catalytic particles. Herein, we found that addition of trace water greatly benefits large-scale synthesis of HCNTs. Uniform HCNTs with - 100% purity can be obtained, and the yield of HCNTs can reach ~ 8,078% in a run of 6 h, much higher than that obtained without trace water and any of the reported yields. Experiments and theoretical simulations are performed to reveal that the trace water can react with the dangling bond on carbon, thus inhibiting the generation of amorphous species. Furthermore, the trace water can enhance the anisotropy of the catalyst surface. This results in different segregation rates of carbon atoms coming out of different crystal planes and further periodic mismatch of the graphite layers, thus leading to the formation of HCNTs. Therefore, this new and efficient method is promising for practical, large-scale production of HCNTs.展开更多
Wearable electromagnetic interference(EMI)shielding fabrics with excellent electromagnetic shielding performance,oxidation resistance,and structural stability are highly demanded for the rapid development of electroni...Wearable electromagnetic interference(EMI)shielding fabrics with excellent electromagnetic shielding performance,oxidation resistance,and structural stability are highly demanded for the rapid development of electronic devices and wireless communication.MXenes are metallic conductive materials with exceptional EMI shielding properties,but they are prone to oxidation in air and have poor structural stability and durability on fabric substrates.Herein,we present a one-step assembly method to fabricate fabrics coated with MXenes and polymeric sodium alginate(SA)composite(MXene-SA).SA protects MXenes from oxidation and forms a stable interlayer structure by bonding to MXenes.The MXene-SA coated fabrics are breathable and flexible,and have a low sheet resistance of 2.12±0.08Ω/sq and a high EMI shielding performance of 37.05 dB at X-band,which is comparable to the best 42.31 dB.Moreover,the MXene-SA coated fabrics exhibit high structural stability and oxidation resistance under various conditions of sonication disintegration,mechanical abuse,chemical corrosion,and humidity,compared to pure MXenes coated fabrics.We believe that the wearable and high-performance MXene-SA fabrics have great potential for the next generation of ultra-portable and wearable EMI shielding products.展开更多
Hydrothermal carbonization(HTC)has been regarded as a promising technique for turning wet biomass into hydrochar due to its low energy consumption,low exhaust gas emissions,etc.In addition,hydrochar is an important so...Hydrothermal carbonization(HTC)has been regarded as a promising technique for turning wet biomass into hydrochar due to its low energy consumption,low exhaust gas emissions,etc.In addition,hydrochar is an important source of dissolved organic matter(DOM),which plays a crucial part in the migration and destiny of pollutants in the environmental medium.However,there are limited studies that focus on the factors that influence the formation of DOM in hydrochar,such as hydrothermal temperature.Therefore,the current study comprehensively characterized the optical properties of DOM within hydrochar derived from sawdust(HDOM)under different hydrothermal temperatures(150-300℃)by Ultraviolet-visible(UV-Vis)and fluorescence spectroscopy,as well as its complexation characteristic with Cu(II).The findings revealed that the organic carbon content of HDOM reached a peak of 37.3 mg L^(−1)when the temperature rose to 240℃and then decreased as the temperature increased.UV-Vis spectroscopy analysis showed that the absorption capacity of HDOM at 275 nm increases with temperature and reaches a maximum value at 240℃,indicating that high temperature promotes the formation of monocyclic aromatic compounds.High temperature enhances the aromaticity,hydrophobicity,and humification degree of HDOM,thus improving its stability and aromaticity.The E3/E4 ratios are all greater than 3.5,confirming that the main component of HDOM is fulvic acid,which corresponds to 3D-EEM and Pearson’s correlation coefficient analysis.The humification index(HIX)of HDOM increased with the rise in hydrothermal temperature(150-240℃),as observed by the three-dimensional excitation-emission matrix spectroscopy(3D-EEMs).After reaching its peak at 240℃,the HIX value gradually dropped in line with the trend of the DOC change.Moreover,the bioavailability(BIX)value of DOM was all high and greater than 1,indicating all the HDOM are readily bioavailable.Two microbial humic substances(C1 and C4),a humic-like substance(C2),and a protein-like substance(C3)were discovered in DOM by integrating 3D-EEMs with parallel factor analysis(PARAFAC).Their fluorescence intensity decreases as the Cu(II)concentration increases,indicating the formation of complexes with Cu(II).As the temperature rises,the binding ability of DOM and Cu(II)changes significantly,reaching the optimum at 300℃.Meanwhile,the substance C2 has the strongest binding ability with Cu(II).This research emphasizes the significance of spectroscopy analysis in determining the evolution of hydrochar-derived DOM,the potential for heavy metal binding and migration,and its characteristics and features.展开更多
文摘Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation of intelligent ships,route planning technologies have developed many route planning algorithms that prioritize economy and safety.This paper conducts an in-depth study of algorithm efficiency for a route planning problem,proposing an intelligent ship route planning algorithm based on the adaptive step size Informed-RRT^(*).This algorithm can quickly plan a short route according to automatic obstacle avoidance and is suitable for planning the routes of intelligent ships.Results show that the adaptive step size Informed-RRT^(*) algorithm can shorten the optimal route length by approximately 13.05%while ensuring the running time of the planning algorithm and avoiding approximately 23.64%of redundant sampling nodes.The improved algorithm effectively circumvents unnecessary calculations and reduces a large amount of redundant sampling data,thus improving the efficiency of route planning.In a complex water environment,the unique adaptive step size mechanism enables this algorithm to prevent restricted search tree expansion,showing strong search ability and robustness,which is of practical significance for the development of intelligent ships.
基金Supported by the Tianjin University of Technology Graduate R esearch Innovation Project(YJ2281).
文摘An improved version of the sparse A^(*)algorithm is proposed to address the common issue of excessive expansion of nodes and failure to consider current ship status and parameters in traditional path planning algorithms.This algorithm considers factors such as initial position and orientation of the ship,safety range,and ship draft to determine the optimal obstacle-avoiding route from the current to the destination point for ship planning.A coordinate transformation algorithm is also applied to convert commonly used latitude and longitude coordinates of ship travel paths to easily utilized and analyzed Cartesian coordinates.The algorithm incorporates a hierarchical chart processing algorithm to handle multilayered chart data.Furthermore,the algorithm considers the impact of ship length on grid size and density when implementing chart gridification,adjusting the grid size and density accordingly based on ship length.Simulation results show that compared to traditional path planning algorithms,the sparse A^(*)algorithm reduces the average number of path points by 25%,decreases the average maximum storage node number by 17%,and raises the average path turning angle by approximately 10°,effectively improving the safety of ship planning paths.
基金financially supported by the National Natural Science Foundation of China(NSFC,No.51903213 and No.5217130190)the Science and Technology Planning Project of Sichuan Province(No.2020YFH0053)Central Government Guides the Local Science and Technology Development Special Funds to freely explore basic research projects(No.2021Szvup124)。
文摘In recent years,graphene-based composite films have been greatly developed in the field of electromagnetic shielding interference(EMI).However,it is still a huge challenge to prepare graphene-based composite films with excellent mechanical properties,conductivity and electromagnetic shielding properties.In this work,we adopted a facile and effective method by annealing the alkali-treated polyacrylonitrile(aPAN)nanofibers reinforced graphene oxide(GO)composite films at 2000°C to obtain graphene-carbon nanofibers composite films(GCFs).Microscopically,carbon nanofibers(CNFs)were intercalated into the graphene sheets,and microgasbags structure was formed during the heat treatment process.The special structure makes GCFs have superior tensile strength(10.4 MPa)at 5%strain.After repeated folding over1000 times,the films still demonstrate excellent structural integrity and flexibility performance.Interestingly,the graphene-based composite films with 10 wt%a PAN nanofibers exhibit an extremely low density of about 0.678 g/cm^(3)and excellent electrical conductivity of 1.72×10^(5)S/m.Further,an outstanding electromagnetic shielding effectiveness(SE)of 55–57 d B was achieved,and the corresponding value of the specific SE/thickness can reach 67,601–70,059 d B·cm^(2)/g,which is the highest among reported graphenebased shielding materials.The significant electromagnetic shielding performance is due to the synergistic enhancement effect brought by the excellent conductivity of carbon nanofibers and graphene,the formed effective conductive network and the microgasbags structure.Electromagnetism simulation further clarified that the underlying mechanism should be mainly attributed to the conduction loss and multiple reflections caused by the special structure of GCFs.This work will provide new solutions for low density,high flexibility and excellent electromagnetic shielding properties materials in the next generation of foldable and wearable electronics.
基金financially supported by the National Natural Science Foundation of China (NSFC,Nos.51903213 and5217130190)the Science and Technology Planning Project of Sichuan Province (No.2020YFH0053)+1 种基金the Central Government Guides the Local Science and Technology Development Special Funds to freely explore basic research projects (No.2021Szvup124)the Fundamental Research Funds for the Central Universities(No.2682021GF004)。
文摘Although lightweight and three-dimensional(3 D) graphene aerogels are highly desirable for microwave absorption(MA) due to their high porosity,specific surface area,and 3 D conductive network,it still remains a large challenge to construct a multifunctional application framework to quickly adapt to the complex practical environment,making it to be efficiently applied in a variety of complex situation.Herein,multifunctional aramid nanofibers(ANFs) reinforced reduced graphene oxide aerogels(RGO@ANF) have been achieved by in-situ gel reaction,freeze-drying,and thermal annealing processes.The introduced ANFs in RGO aerogels can prevent the graphene sheets from over-stacking and enhance the connectivity of cell walls,thus leading to excellent compression resistance,MA,sound absorption,and thermal insulation performance.Under 70% strain,the maximum compressive stress of RGO@ANF aerogel reaches78.8 kPa,and reversible compressibility with reliable resistance to fatigue for 100 compressive cycles at20% strain.Further,the RGO@ANF aerogel exhibit a minimum reflection loss(RL_(min)) of-56.5 dB and a maximum effective absorption bandwidth(EAB) of 7.0 GHz at a thickness of 2.8 mm,basically covering the X and Ku bands.Moreover,the hybrid aerogel exhibited excellent sound absorption with an average absorption coefficient> 0.56 at 2-6 kHz and good thermal insulation performance with low thermal conductivity of about 49.18 mW m-1K-1.The integrated graphene aerogels with such multifunctional performances hold a great promise for applications such as MA,sound absorption,and heat insulation.
基金Project support by the National Natural Science Foundation of China(Grant Nos.11674237 and 51602211)the National Key Research and Development Program of China(Grant No.2016YFB0700700)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),ChinaChina Post-doctoral Foundation(Grant No.7131705619).
文摘Traditional materials discovery is in ‘trial-and-error’ mode, leading to the issues of low-efficiency, high-cost, and unsustainability in materials design. Meanwhile, numerous experimental and computational trials accumulate enormous quantities of data with multi-dimensionality and complexity, which might bury critical ‘structure–properties’ rules yet unfortunately not well explored. Machine learning(ML), as a burgeoning approach in materials science, may dig out the hidden structure–properties relationship from materials bigdata, therefore, has recently garnered much attention in materials science. In this review, we try to shortly summarize recent research progress in this field, following the ML paradigm:(i) data acquisition →(ii) feature engineering →(iii) algorithm →(iv) ML model →(v) model evaluation →(vi) application. In section of application, we summarize recent work by following the ‘material science tetrahedron’:(i) structure and composition →(ii) property →(iii) synthesis →(iv) characterization, in order to reveal the quantitative structure–property relationship and provide inverse design countermeasures. In addition, the concurrent challenges encompassing data quality and quantity, model interpretability and generalizability, have also been discussed. This review intends to provide a preliminary overview of ML from basic algorithms to applications.
文摘The movements and intentions of other ships can be determined by gathering and examining ship sound signals.The extraction and analysis of ship sound signals fundamentally support the autonomous navigation of intelligent ships.Mel scale frequency cepstral coefficient(MFCC)feature parameters are improved and optimized to form NewMFCC by introducing second-order difference and wavelet packet decomposition transformation methods in this paper.Transforming sound signals into a feature vector that fully describes the dynamic characteristics of ship sound signals and the high-and low-frequency information solves the problem of the inability to transport ordinary sound signals directly as signals for training in machine learning models.Radial basis function kernels are used to conduct support vector machine classifier simulation experiments.Five types of sound signals,namely,one type of ship sound signals and four types of interference sound signals,are categorized and identified as classification targets to verify the feasibility of the classification of ship sound signals and interference signals.The proposed method improves classification accuracy by approximately 15%.
文摘This paper deals with a series of novel processing techniques based on the in situ production of metal matrix composites (MMCs). In situ techniques involve a chemical reaction resulting in the formation of a very fine and thermodynamically stable reinforcing ceramic phase within a metal matrix. As a result, this provides thermodynamic compatibility at the matrix-reinforcement interface. The reinforcement surfaces are also likely to be free of contamination and, therefore, a stronger matrix-dispersion bond can be achieved. Some of these technologies including DIMOX^? XD, PRIMEX^? reactive gas infiltration, high-temperature self-propagating synthesis (SHS), and liquid-solid, or solid-gas-liquid reactions as well as plasma in situ MMCs are expressed in this paper.
基金supported by the National Nat-ural Science Foundation of China(NSFC,Nos.51903213 and 5217130190)the Science and Technology Planning Project of Sichuan Province(Nos.2023NSFSC1952 and 2022ZYD0028)+1 种基金the Central Government Guides the Local Science and Technology Development Special Funds(No.2021Szvup124)the Fundamental Research Funds for the Central Universities(Nos.2682021GF004 and 2682022CG005)to freely explore basic research projects.
文摘Fabrics,a class of carriers,have been pioneered in electromagnetic protection,but their microwave absorbing potential has not been fully explored for a considerable period.Herein,aramid nanofibers(ANFs)enhanced reduced graphene oxide fabrics(ANF/rGO fabrics)were synthesized by wet spinning-chemical reduction.The ANF/rGO fabrics can achieve the minimum reflection loss(RLmin)of−15.8 dB with a thickness of 2.7 mm.On this basis,ANF/rGO fabrics grown with polyaniline(ANF/rGO-PANi fabrics)through in-situ doping polymerization were obtained.Polyaniline compensates for the lack of conductivity of the dielectric fabrics,bringing higher impedance matching and attenuation capability.The corresponding RLmin can reach−52.3 dB under 2.9 mm and the effective absorption bandwidth(EAB)increases to 6 GHz covering the whole Ku band under 2.5 mm.The fabrics woven by high-strength graphene-based hybrid fibers proposed in this study provide a new angle to achieve high-efficiency microwave absorption.
基金financially supported by the National Natural Science Foundation of China(NSFC,no.52472305,no.52173265,no.52302087 and no.52403049)the Science and Technology Planning Project of Sichuan Province(no.2023NSFSC1952 and 2022ZYD0028)+1 种基金the Central Government Guides the Local Science and Technology Development Special Funds,Innovation and Technology Commission-Hong Kong(no.2021Szvup124)the Fundamental Research Funds for the Central Universities(nos.2682021GF004 and 2682022CG005)to freely explore basic research projects.
文摘Fabrics have attracted significant attention in the field of electromagnetic shielding due to their unique grid structure,high electrical conductivity,and flexibility.To enrich the research of textiles for microwave absorption,two-dimensional transition metal carbide(MXene)-enhanced reduced graphene oxide-based fabrics(MXene/RGO fabrics)were synthesized in this paper by using wet spinning–ionic cross-linking–chemical reduction strategy.MXene/RGO fabrics achieve a minimum reflection loss of−58.3 dB at 17.6 GHz and a thickness of 2.4 mm,with an effective absorption bandwidth of 4.92 GHz.In addition,the combination of electromagnetic finite element simulation technology and test results was used to further elucidate the response mode and loss mechanism of MXene/RGO fabrics.The MXene/RGO composite fibers exhibit a tuned attenuation ability and impedance matching performance,which is attributed to the increased polarization relaxation loss caused by the large number of heterogeneous interfaces between RGO,MXene,and TiO2 particles,as well as the appropriate electrical conductivity(16.6 S/cm).MXene/RGO fibers exhibit excellent microwave absorption performance,mechanical strength(534 MPa),easy modification,and fatigue resistance,promising stable absorption of electromagnetic waves in complex environments,thereby expanding the application scenarios of fabrics in the field of microwave absorption.
基金supported by the National Natural Science Foundation of China(Nos.52472305,52173265,52302087, 52403049)the Science and Technology Planning Project of Sichuan Province(No.2023NSFSC1952)the Fundamental Research Funds for the Central Universities(No.2682021GF004)to freely explore basic research projects.
文摘Despite significant advancements in microwave absorption materials(MAMs)for electromagnetic interference mitigation,the integration of robust microwave absorption(MA)and corrosion resistance into a unified system remains a critical challenge,particularly for long-term durability in harsh environments.Conventional approaches relying on multiphase composites often suffer from compromised functionality due to intrinsic property conflicts between absorption and anti-corrosion components.Here,we propose an integrated design strategy of active-passive corrosion inhibition and MA to design composite volatile corrosion inhibition coatings with synergistic dielectric attenuation and multiple corrosion protection effects.Dielectric property modulation strategy-based,we achieved precise modulation of permittivity gradients and interfacial polarization for RGO/FCIP@SiO_(2),resulting in optimal impedance matching and record-breaking MA performance:a minimal reflection loss(RL_(min))of-68 dB at 12.82 GHz with a 7 GHz effective absorption bandwidth(EAB)at 2.0 mm thickness.Moreover,the two-dimensional lamellar reduced graphene oxide(RGO)has a“maze effect”and superhydrophobic architecture(162.3°contact angle)to passively defend against corrosive media.Concurrently,the multicomponent volatile corrosion inhibitor(BGC)system endows the composite with exceptional active corrosion inhibition.Through the dynamic anti-corrosion process involving vapor-phase release,surface adsorption,and protective film formation of corrosion inhibitor molecules,this system significantly enhances corrosion protection.Remarkably,it maintains 99.36%corrosion inhibition efficiency after 360-hour salt spray exposure and 25 friction cycles,without MA performance degradation.
基金the National Natural Science Foundation of China (No.51573149)the Fundamental Research Funds for the Central Universities (No.2682016CX069)+1 种基金the Science and Technology Planning Project of Sichuan Province (Nos.2018GZ0132 and 2018GZ0427)Sichuan Province Science and Technology Innovation Talent Project (No.2017072).
文摘Recently,biomass-derived three-dimensional (3D) porous carbon materials have been gaining more interest as promising microwave absorbers due to their low cost,vast availability,and sustainability.Here,a novel 3D interconnected porous magnetic carbon foams are in-situ synthesized via a combination of sol-gel and carbonization process with wheat straw as the carbon source and FeCl3·6H2O as the magnetic regulating agent.During the process of foams formation,the lignocelluloses from the steam-exploded wheat straw are converted into interconnected carbon sheet networks with hierarchical porous structures,and the precursor FeCl3·6H2O is converted into magnetic nanoparticles uniformly embedded in the porous carbon foams.The generated magnetic nanoparticles are benefit to enhance the interface polarization and magnetic loss ability to improve the efficient complementarities between the dielectric and magnetic loss,thus increasing the impedance matching.The obtained sample treated at 600 ℃ displays the best microwave absorption (MA) performance.It presents a minimal reflection loss (RL) of-43.6 dB at 7.1 GHz and the effective bandwidth (RL <-10 dB) is 3.3 GHz with the thickness of 4.7 mm.The 3D porous structure,multi-interfaces and the synergy of dielectric loss and magnetic loss make great contribution to the outstanding MA performance.
基金This work was financially supported by the National Natural Science Foundation of China （No. 51573149）, the Science and Technology Planning Project of Sichuan Province （No. 2016GZ0224）, the Fundamental Research Funds for the Central Universities （No. 2682016CX069） and the Student Research Training Program （No. 2017005）.
文摘Despite recent progress in the synthesis and application of graphene-based aerogels, some challenges such as scalable and cost-effective production, and miniaturization still remain, which hinder the practical application of these materials. Here we report a large-scale electrospinning method to generate graphene-based aerogel microspheres （AMs）, which show broadband, tunable and high-performance microwave absorption. Graphene/Fe3O4 AMs with a large number of openings with hierarchical connecting radial microcharmels can be obtained via electrospinning-freeze drying followed by calcination. Importantly, for a given Fe3O4：graphene mass ratio, altering the shape of aerogel monoliths or powders into aerogel microspheres leads to unique electromagnetic wave properties. As expected, the reflection loss of graphene/Fe3O4 AMs-1：1 with only 5 wt.% absorber loading reaches -51.5 dB at 9.2 GHz with a thickness of 4.0 mm and a broad absorption bandwidth （RL 〈-10 dB） of 6.5 GHz. Furthermore, switching to coaxial electrospinning enables the fabrication of SiO2 coatings to construct graphene/Fe3O4@SiO2 core-shell AMs. The coatings influence the electromagnetic wave absorption of graphene/Fe3O4 AMs significantly. In view of these advantages, we believe that this processing technique may be extended to fabricate a wide range of unique graphene-based architectures for functional design and applications.
基金This work was financially supported by the National Natural Science Foundation of China(No.51903213)the Science and Technology Planning Project of Sichuan Province(Nos.2018GZ0132 and 2018GZ0427).
文摘Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-specific needs.Herein,we highlight graphene aerogel spheres with controllable hollow structures(HGAS)that are delicately designed and manufactured via coaxial electrospinning coupled with freeze-drying and calcination.The HGAS exhibit a spherical configuration at the macroscale,while the construction elements of graphene on the microscale showing an interconnected radial microchannel structure.Further ball-in-ball graphene aerogel spheres(BGAS)are obtained by reference to the triaxial electrospinning technology.The as-prepared spheres possess the controllable integrated conductive networks,leading to the effective dielectric loss and impedance matching thus bringing on high-performance microwave absorption.The as-obtained HGAS shows a minimum reflection loss of-52.7 dB and a broad effective absorption bandwidth(f)of 7.0 GHz with thickness of 2.3 mm.Further,the fe reaches 9.3 GHz for BGAS with thickness of 3.4 mm.Aforementioned superior microwave absorption of HGAS and BGAS confirms combination of multiaxial electrospinning and freeze-drying on the multiscale is an effective strategy for scalable fabrication of advanced microwave.absorbing functional graphene aerogel spheres.
基金supported by the National Natural Science Foundation of China(Nos.51903213 and 5217130190)the Science and Technology Planning Project of Sichuan Province(Nos.2023NSFSC1952 and 2022ZYD0028)+1 种基金the Central Government Guides Local Science and Technology Development Special Funds to freely explore basic research projects(No.2021Szvup124)the Fundamental Research Funds for the Central Universities(No.2682021GF004).
文摘In order to meet the requirements of the marine environment for microwave absorption(MA)materials,we put forward the strategy of constructing multi-functional composite materials,which integrate microwave absorption,anti-corrosion,and antibacterial properties.Herein,graphene oxide(GO)was used as a template to induce the growth of zeolitic imidazolate framework-8(ZIF-8),simultaneously as a two-dimensional(2D)nanocontainers to load corrosion inhibitors to achieve pH-responsive and self-healing properties.Finally,quaternary ammonium salt(dimethyl octadecyl(3-trimethoxylsilyl propyl)ammonium chloride(DMAOP))and sodium ascorbate(VCNa)were introduced to achieve synergistic antibacterial activity and the reduction of GO.The 2D strip-like structure of ZIF-8 was due to the confined growth induced by the electrostatic attraction between ZIF-8 and GO sheets.The as-obtained reduced GO(RGO)/ZIF-8/DMAOP5 exhibited excellent microwave absorption(MA)properties,with a minimum reflection loss(RL)value of-47.08 dB at 12.73 GHz when the thickness was 2.8 mm.Moreover,the effective absorption bandwidth reached 6.84 GHz.After soaking in 3.5%NaCl solution for 35 days,the RGO/ZIF-8/DMAOP5-0.7%coating still achieved an impedance value of 4.585×107Ω·cm^(2) and a protective efficiency of 99.994%,providing superior anti-corrosion properties.In addition,fantastic antibacterial activity was obtained,with the antibacterial rates of RGO/ZIF-8/DMAOP_(10) reaching 99.39%and 100%against Escherichia coli and Staphylococcus aureus.This work could open new avenues towards the development of a new generation of multifunctional MA materials.
文摘Helical carbon nanotubes （HCNTs） are highly desirable due to their unique geometrical elegance and inherent physical properties; however, high-efficiency synthesis of high-purity HCNTs with high yield and full elucidation of their growth mechanism remains challenging. Traditional methods to achieve the high-yield growth of HCNTs mainly focus on controlling the size of catalytic particles. Herein, we found that addition of trace water greatly benefits large-scale synthesis of HCNTs. Uniform HCNTs with - 100% purity can be obtained, and the yield of HCNTs can reach ~ 8,078% in a run of 6 h, much higher than that obtained without trace water and any of the reported yields. Experiments and theoretical simulations are performed to reveal that the trace water can react with the dangling bond on carbon, thus inhibiting the generation of amorphous species. Furthermore, the trace water can enhance the anisotropy of the catalyst surface. This results in different segregation rates of carbon atoms coming out of different crystal planes and further periodic mismatch of the graphite layers, thus leading to the formation of HCNTs. Therefore, this new and efficient method is promising for practical, large-scale production of HCNTs.
基金the National Natural Science Foundation of China(No.52173236)the Sichuan Science and Technology Program(No.2023NSFSC0410).
文摘Wearable electromagnetic interference(EMI)shielding fabrics with excellent electromagnetic shielding performance,oxidation resistance,and structural stability are highly demanded for the rapid development of electronic devices and wireless communication.MXenes are metallic conductive materials with exceptional EMI shielding properties,but they are prone to oxidation in air and have poor structural stability and durability on fabric substrates.Herein,we present a one-step assembly method to fabricate fabrics coated with MXenes and polymeric sodium alginate(SA)composite(MXene-SA).SA protects MXenes from oxidation and forms a stable interlayer structure by bonding to MXenes.The MXene-SA coated fabrics are breathable and flexible,and have a low sheet resistance of 2.12±0.08Ω/sq and a high EMI shielding performance of 37.05 dB at X-band,which is comparable to the best 42.31 dB.Moreover,the MXene-SA coated fabrics exhibit high structural stability and oxidation resistance under various conditions of sonication disintegration,mechanical abuse,chemical corrosion,and humidity,compared to pure MXenes coated fabrics.We believe that the wearable and high-performance MXene-SA fabrics have great potential for the next generation of ultra-portable and wearable EMI shielding products.
基金supported by the Outstanding Youth Research Project in Anhui Provincial Scientific Research Plan Project(2022AH020089)Anhui Province University Top Talent Funding Project(gxbjZD2021069)+1 种基金Excellent Scientific Research and Innovation Team of Universities in Anhui Province(2023AH010062)Commissioned R&D project(ZHEP2021001,BOFA202007).
文摘Hydrothermal carbonization(HTC)has been regarded as a promising technique for turning wet biomass into hydrochar due to its low energy consumption,low exhaust gas emissions,etc.In addition,hydrochar is an important source of dissolved organic matter(DOM),which plays a crucial part in the migration and destiny of pollutants in the environmental medium.However,there are limited studies that focus on the factors that influence the formation of DOM in hydrochar,such as hydrothermal temperature.Therefore,the current study comprehensively characterized the optical properties of DOM within hydrochar derived from sawdust(HDOM)under different hydrothermal temperatures(150-300℃)by Ultraviolet-visible(UV-Vis)and fluorescence spectroscopy,as well as its complexation characteristic with Cu(II).The findings revealed that the organic carbon content of HDOM reached a peak of 37.3 mg L^(−1)when the temperature rose to 240℃and then decreased as the temperature increased.UV-Vis spectroscopy analysis showed that the absorption capacity of HDOM at 275 nm increases with temperature and reaches a maximum value at 240℃,indicating that high temperature promotes the formation of monocyclic aromatic compounds.High temperature enhances the aromaticity,hydrophobicity,and humification degree of HDOM,thus improving its stability and aromaticity.The E3/E4 ratios are all greater than 3.5,confirming that the main component of HDOM is fulvic acid,which corresponds to 3D-EEM and Pearson’s correlation coefficient analysis.The humification index(HIX)of HDOM increased with the rise in hydrothermal temperature(150-240℃),as observed by the three-dimensional excitation-emission matrix spectroscopy(3D-EEMs).After reaching its peak at 240℃,the HIX value gradually dropped in line with the trend of the DOC change.Moreover,the bioavailability(BIX)value of DOM was all high and greater than 1,indicating all the HDOM are readily bioavailable.Two microbial humic substances(C1 and C4),a humic-like substance(C2),and a protein-like substance(C3)were discovered in DOM by integrating 3D-EEMs with parallel factor analysis(PARAFAC).Their fluorescence intensity decreases as the Cu(II)concentration increases,indicating the formation of complexes with Cu(II).As the temperature rises,the binding ability of DOM and Cu(II)changes significantly,reaching the optimum at 300℃.Meanwhile,the substance C2 has the strongest binding ability with Cu(II).This research emphasizes the significance of spectroscopy analysis in determining the evolution of hydrochar-derived DOM,the potential for heavy metal binding and migration,and its characteristics and features.
