The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly comple...The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly complex layout combinations.Furthermore,due to constraints in component quantity and geometry within the cross-sectional layout,filler bodies must be incorporated to maintain cross-section performance.Conventional design approaches based on manual experience suffer from inefficiency,high variability,and difficulties in quantification.This paper presents a multi-level automatic filling optimization design method for umbilical cross-sectional layouts to address these limitations.Initially,the research establishes a multi-objective optimization model that considers compactness,balance,and wear resistance of the cross-section,employing an enhanced genetic algorithm to achieve a near-optimal layout.Subsequently,the study implements an image processing-based vacancy detection technique to accurately identify cross-sectional gaps.To manage the variability and diversity of these vacant regions,the research introduces a multi-level filling method that strategically selects and places filler bodies of varying dimensions,overcoming the constraints of uniform-size fillers.Additionally,the method incorporates a hierarchical strategy that subdivides the complex cross-section into multiple layers,enabling layer-by-layer optimization and filling.This approach reduces manufac-turing equipment requirements while ensuring practical production process feasibility.The methodology is validated through a specific umbilical case study.The results demonstrate improvements in compactness,balance,and wear resistance compared with the initial cross-section,offering novel insights and valuable references for filler design in umbilical cross-sections.展开更多
As a key node of modern transportation network,the informationization management of road tunnels is crucial to ensure the operation safety and traffic efficiency.However,the existing tunnel vehicle modeling methods ge...As a key node of modern transportation network,the informationization management of road tunnels is crucial to ensure the operation safety and traffic efficiency.However,the existing tunnel vehicle modeling methods generally have problems such as insufficient 3D scene description capability and low dynamic update efficiency,which are difficult to meet the demand of real-time accurate management.For this reason,this paper proposes a vehicle twin modeling method for road tunnels.This approach starts from the actual management needs,and supports multi-level dynamic modeling from vehicle type,size to color by constructing a vehicle model library that can be flexibly invoked;at the same time,semantic constraint rules with geometric layout,behavioral attributes,and spatial relationships are designed to ensure that the virtual model matches with the real model with a high degree of similarity;ultimately,the prototype system is constructed and the case region is selected for the case study,and the dynamic vehicle status in the tunnel is realized by integrating real-time monitoring data with semantic constraints for precise virtual-real mapping.Finally,the prototype system is constructed and case experiments are conducted in selected case areas,which are combined with real-time monitoring data to realize dynamic updating and three-dimensional visualization of vehicle states in tunnels.The experiments show that the proposed method can run smoothly with an average rendering efficiency of 17.70 ms while guaranteeing the modeling accuracy(composite similarity of 0.867),which significantly improves the real-time and intuitive tunnel management.The research results provide reliable technical support for intelligent operation and emergency response of road tunnels,and offer new ideas for digital twin modeling of complex scenes.展开更多
In recent years,medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances.By controlling reasonable elemental composition and processing parameters,the medium entro...In recent years,medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances.By controlling reasonable elemental composition and processing parameters,the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower costs.In this paper,a FeCoNi medium entropy alloy precursor was prepared via sol-gel and coprecipitation methods,respectively,and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen reduction.The phases and magnetic properties of FeCoNi medium entropy alloy were investigated.Results showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500℃.Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal reduction.The alloy prepared by hydrogen reduction was uniform and showed a relatively high purity.Moreover,the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.展开更多
The influence of Nb-V microalloying on the hot deformation behavior and microstructures of medium Mn steel(MMS)was investigated by uniaxial hot compression tests.By establishing the constitutive equations for simulati...The influence of Nb-V microalloying on the hot deformation behavior and microstructures of medium Mn steel(MMS)was investigated by uniaxial hot compression tests.By establishing the constitutive equations for simulating the measured flow curves,we successfully constructed deformation activation energy(Q)maps and processing maps for identifying the region of flow instability.We concluded the following consequences of Nb-V alloying for MMS.(i)The critical strain increases and the increment diminishes with the increasing deformation temperature,suggesting that NbC precipitates more efficiently retard dynamic recrystallization(DRX)in MMS compared with solute Nb.(ii)The deformation activation energy of MMS is significantly increased and even higher than that of some reported high Mn steels,suggesting that its ability to retard DRX is greater than that of the high Mn content.(iii)The hot workability of MMS is improved by narrowing the hot processing window for the unstable flow stress,in which fine recrystallized and coarse unrecrystallized grains are present.展开更多
The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (...The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (H/MEAs) still lacks effective atomic-scale composition design and screening schemes, which hinders the accurate prediction of desired composition and properties. This study proposes a novel approach for rapidly designing the composition of materials with the aim of overcoming the trade-off between strength and ductility in metal matrix composites. The effect of chemical composition on stacking fault energy (SFE), shear modulus, and phase stability was investigated through the use of molecular dynamics (MD) and thermodynamic calculation software. The alloy's low SFE, highest shear modulus, and stable face-centered cubic (FCC) phase have been identified as three standard physical quantities for rapid screening to characterize the deformation mechanism, ultimate tensile strength, phase stability, and ductility of the alloy. The calculation results indicate that the optimal composition space is expected to fall within the ranges of 17 %–34 % Ni, 33 %–50 % Co, and 25 %–33 % Mn. The comparison of stress-strain curves for various predicted components using simulated and experimental results serves to reinforce the efficacy of the method. This indicates that the screening criteria offer a necessary design concept, deviating from traditional strategies and providing crucial guidance for the rapid development and application of MEAs.展开更多
Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxi...Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxide fuel cells(SOFCs)represents an efficient and promising strategy for its effective utilization.However,direct application in Ni-based anodes induces carbon deposition,which severely degrades cell performance.Herein,a medium-entropy oxide Sr_(2)FeNi_(0.1)Cr_(0.3)Mn_(0.3)Mo_(0.3)O_(6−δ)(SFNCMM)was developed as an anode internal reforming catalyst.Following reduction treatment,FeNi_(3) nano-alloy particles precipitate on the surface of the material,thereby significantly enhancing its catalytic activity for LC-CMM reforming process.The catalyst achieved a methane conversion rate of 53.3%,demonstrating excellent catalytic performance.Electrochemical evaluations revealed that SFNCMM-Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)with a weight ratio of 7:3 exhibited superior electrochemical performance when employed as the anodic catalytic layer.With H_(2) and LC-CMM as fuels,the single cell achieved maximum power densities of 1467.32 and 1116.97 mW·cm^(−2) at 800℃,respectively,with corresponding polarization impedances of 0.17 and 1.35Ω·cm^(2).Furthermore,the single cell maintained stable operation for over 100 h under LC-CMM fueling without significant carbon deposition,confirming its robust resistance to carbon formation.These results underscore the potential of medium-entropy oxides as highly effective catalytic layers for mitigating carbon deposition in SOFCs.展开更多
BACKGROUND Oil-based iodinated contrast media have excellent contrast properties and are widely used for hysterosalpingographic evaluation of female infertility.On abdominal radiography and computed tomography(CT)scan...BACKGROUND Oil-based iodinated contrast media have excellent contrast properties and are widely used for hysterosalpingographic evaluation of female infertility.On abdominal radiography and computed tomography(CT)scans,their radiodensity is similar to that of metallic objects,which can sometimes lead to diagnostic confusion in the postoperative settings.In this case,retained oil-based contrast medium was observed on an abdominal radiograph following a cesarean section,making it difficult to differentiate from an intraperitoneal foreign body from surgery.The patient was a 37-year-old pregnant woman who was referred to our hospital at 32 weeks and 1 day of pregnancy due to complete placenta previa for mana-gement of pregnancy and delivery.An elective cesarean section was performed at 37 weeks and 3 days.A plain abdominal radiograph taken immediately after surgery revealed a near-round,hyperdense,mass-like shadow with a regular margin in the pelvic cavity.An intraperitoneal foreign body was suspected;therefore,an abdominal CT scan was performed.The foreign body was located on the left side of the pouch of Douglas and had a CT value of 7000 Hounsfield units,similar to that of metals.The CT value strongly suggested the presence of an artificial object.However,further inquiries with the patient and her previous physician revealed a history of hysterosalpingography.Accordingly,retained oil-based iodinated contrast medium was suspected,and observation of the object’s course was adopted.CONCLUSION When intraperitoneal foreign bodies are suspected on postoperative radiographs,the possibility of oil-based iodinated contrast medium retention should be considered.展开更多
[Objectives]To evaluate the performance of two rapid chromogenic media for the detection of Bacillus cereus in milk powder,and verify the media's inclusivity,exclusivity,and accuracy,and to assess their applicabil...[Objectives]To evaluate the performance of two rapid chromogenic media for the detection of Bacillus cereus in milk powder,and verify the media's inclusivity,exclusivity,and accuracy,and to assess their applicability for the quantitative detection of B.cereus.[Methods]B.cereus in milk powder samples was quantified using two rapid chromogenic media in combination with the national standard method.Agreement between the quantitative results from the three methods was subsequently assessed for agreement via a paired t-test.[Results]No significant differences were observed between the bacterial counts yielded by the two rapid chromogenic media and the national standard method(P>0.05),with excellent agreement between them.[Conclusions]The method of rapid chromogenic culture medium is rapid and simple.展开更多
Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,ther...Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,there is limited research on the spatiotemporal characteristics of landslide deformation.This paper proposes a novel Multi-Relation Spatiotemporal Graph Residual Network with Multi-Level Feature Attention(MFA-MRSTGRN)that effectively improves the prediction performance of landslide displacement through spatiotemporal fusion.This model integrates internal seepage factors as data feature enhancements with external triggering factors,allowing for accurate capture of the complex spatiotemporal characteristics of landslide displacement and the construction of a multi-source heterogeneous dataset.The MFA-MRSTGRN model incorporates dynamic graph theory and four key modules:multilevel feature attention,temporal-residual decomposition,spatial multi-relational graph convolution,and spatiotemporal fusion prediction.This comprehensive approach enables the efficient analyses of multi-source heterogeneous datasets,facilitating adaptive exploration of the evolving multi-relational,multi-dimensional spatiotemporal complexities in landslides.When applying this model to predict the displacement of the Liangshuijing landslide,we demonstrate that the MFA-MRSTGRN model surpasses traditional models,such as random forest(RF),long short-term memory(LSTM),and spatial temporal graph convolutional networks(ST-GCN)models in terms of various evaluation metrics including mean absolute error(MAE=1.27 mm),root mean square error(RMSE=1.49 mm),mean absolute percentage error(MAPE=0.026),and R-squared(R^(2)=0.88).Furthermore,feature ablation experiments indicate that incorporating internal seepage factors improves the predictive performance of landslide displacement models.This research provides an advanced and reliable method for landslide displacement prediction.展开更多
The dynamics of fluid and non-buoyant particles in a librating horizontal annulus is studied experimentally.In the absence of librations,the granular material forms a cylindrical layer near the outer boundary of the a...The dynamics of fluid and non-buoyant particles in a librating horizontal annulus is studied experimentally.In the absence of librations,the granular material forms a cylindrical layer near the outer boundary of the annulus and undergoes rigid-body rotation with the fluid and the annulus.It is demonstrated that the librational liquefaction of the granular material results in pattern formation.This self-organization process stems from the excitation of inertial modes induced by the oscillatory motion of liquefied granular material under the influence of the gravitational force.The inertial wave induces vortical fluid flow which entrains particles from rest and forms eroded areas that are equidistant from each other along the axis of rotation.Theoretical analysis and experiments demonstrate that a liquefied layer of granular material oscillates with a radian frequency equal to the angular velocity of the annulus and interacts with the inertial wave it excites.The new phenomenon of libration-induced pattern formation is of practical interest as it can be used to control multiphase flows and mass transfer in rotating containers in a variety of industrial processes.展开更多
As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could ra...As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could range from kilometers to tens of kilometers, and even hundreds and thousands of kilometers. Therefore, it is crucial to develop effective long-range path planning for lunar rovers to meet the demands of lunar patrol exploration. This paper presents a hierarchical map model path planning method that utilizes the existing high-resolution images, digital elevation models and mineral abundance maps. The objective is to address the issue of the construction of lunar rover travel costs in the absence of large-scale, high-resolution digital elevation models. This method models the reference and semantic layers using the middle- and low-resolution remote sensing data. The multi-scale obstacles on the lunar surface are extracted by combining the deep learning algorithm on the high-resolution image, and the obstacle avoidance layer is modeled. A two-stage exploratory path planning decision is employed for long-distance driving path planning on a global–local scale. The proposed method analyzes the long-distance accessibility of various areas of scientific significance, such as Rima Bode. A high-precision digital elevation model is created using stereo images to validate the method. Based on the findings, it can be observed that the entire route spans a distance of 930.32 km. The route demonstrates an impressive ability to avoid meter-level impact craters and linear structures while maintaining an average slope of less than 8°. This paper explores scientific research by traversing at least seven basalt units, uncovering the secrets of lunar volcanic activities, and establishing ‘golden spike’ reference points for lunar stratigraphy. The final result of path planning can serve as a valuable reference for the design, mission demonstration, and subsequent project implementation of the new manned lunar rover.展开更多
Thyroid nodules,a common disorder in the endocrine system,require accurate segmentation in ultrasound images for effective diagnosis and treatment.However,achieving precise segmentation remains a challenge due to vari...Thyroid nodules,a common disorder in the endocrine system,require accurate segmentation in ultrasound images for effective diagnosis and treatment.However,achieving precise segmentation remains a challenge due to various factors,including scattering noise,low contrast,and limited resolution in ultrasound images.Although existing segmentation models have made progress,they still suffer from several limitations,such as high error rates,low generalizability,overfitting,limited feature learning capability,etc.To address these challenges,this paper proposes a Multi-level Relation Transformer-based U-Net(MLRT-UNet)to improve thyroid nodule segmentation.The MLRTUNet leverages a novel Relation Transformer,which processes images at multiple scales,overcoming the limitations of traditional encoding methods.This transformer integrates both local and global features effectively through selfattention and cross-attention units,capturing intricate relationships within the data.The approach also introduces a Co-operative Transformer Fusion(CTF)module to combine multi-scale features from different encoding layers,enhancing the model’s ability to capture complex patterns in the data.Furthermore,the Relation Transformer block enhances long-distance dependencies during the decoding process,improving segmentation accuracy.Experimental results showthat the MLRT-UNet achieves high segmentation accuracy,reaching 98.2% on the Digital Database Thyroid Image(DDT)dataset,97.8% on the Thyroid Nodule 3493(TG3K)dataset,and 98.2% on the Thyroid Nodule3K(TN3K)dataset.These findings demonstrate that the proposed method significantly enhances the accuracy of thyroid nodule segmentation,addressing the limitations of existing models.展开更多
Deep learning networks are increasingly exploited in the field of neuronal soma segmentation.However,annotating dataset is also an expensive and time-consuming task.Unsupervised domain adaptation is an effective metho...Deep learning networks are increasingly exploited in the field of neuronal soma segmentation.However,annotating dataset is also an expensive and time-consuming task.Unsupervised domain adaptation is an effective method to mitigate the problem,which is able to learn an adaptive segmentation model by transferring knowledge from a rich-labeled source domain.In this paper,we propose a multi-level distribution alignment-based unsupervised domain adaptation network(MDA-Net)for segmentation of 3D neuronal soma images.Distribution alignment is performed in both feature space and output space.In the feature space,features from different scales are adaptively fused to enhance the feature extraction capability for small target somata and con-strained to be domain invariant by adversarial adaptation strategy.In the output space,local discrepancy maps that can reveal the spatial structures of somata are constructed on the predicted segmentation results.Then thedistribution alignment is performed on the local discrepancies maps across domains to obtain a superior discrepancy map in the target domain,achieving refined segmentation performance of neuronal somata.Additionally,after a period of distribution align-ment procedure,a portion of target samples with high confident pseudo-labels are selected as training data,which assist in learning a more adaptive segmentation network.We verified the superiority of the proposed algorithm by comparing several domain adaptation networks on two 3D mouse brain neuronal somata datasets and one macaque brain neuronal soma dataset.展开更多
The energy-focusing blast is an innovative and ingenious method to achieve directional fracturing.Understanding its energy regulation mechanism is critical to enhancing its practical effectiveness.This study investiga...The energy-focusing blast is an innovative and ingenious method to achieve directional fracturing.Understanding its energy regulation mechanism is critical to enhancing its practical effectiveness.This study investigates the energy regulation mechanism and explores the medium-filling effects within the energy-focusing blast by employing theoretical analysis,numerical simulations,and model tests.The findings by theoretical and numerical analysis first reveal that two stages of the fracturing and tensile stage govern the directionally crack propagation,in which the explosion energy in the non-energyfocusing direction is suppressed,compressing the borehole wall,while redirected energy produces tensile stress in the energy-focusing direction,driving the formation of directional cracks.The choice of filling medium significantly affects directional cracking due to its impact on energy distribution and regulation,and key properties such as wave impedance and compressibility of the filling medium are critical.Experimental comparisons using air,sand,and water as filling media further disclose the distinct effects of the medium on energy regulation and directional crack growth of the energy-focusing blast.The maximum shaped-energy coefficients for air,sand,and water are 1.30,4.41,and 6.12 in the energy-focusing direction,respectively.Meanwhile,the stress attenuation rate of air,sand,and water increases in that order.The higher wave impedance and lower compressibility of water support efficient and uniform energy propagation,which subtly enhances the tensile actions in the focusing direction and intensifies the overall stress impact of the energy-focusing blast.In addition,the stresses in the non-energyfocusing directions decrease as the angle from the energy-focusing direction increases,while the stresses are relatively uniform for both air and water but noticeably uneven for sand;meanwhile,the fractal dimensions of blasting cracks in the case of air,water,and sand are 1.076,1.068,and 1.112,respectively.Sand as a filling medium leads to increased crack irregularities due to its granularity and heterogeneity.The water medium strikes an optimal balance by promoting the blasting energy transition and optimizing the energy distribution,maintaining the least flatness of the directional crack during energy-focusing blasts.展开更多
The phase constitution,microstructure,damping capacity,and mechanical properties of as-cast AlxCrFe3Ni(x=0.5,0.52,0.54,and 0.56,respectively)medium entropy alloys were investigated.It is found that the volume fraction...The phase constitution,microstructure,damping capacity,and mechanical properties of as-cast AlxCrFe3Ni(x=0.5,0.52,0.54,and 0.56,respectively)medium entropy alloys were investigated.It is found that the volume fraction of BCC phase increases while that of FCC decreases with increasing the Al content.When the content of Al is 0.54,the alloy is composed of 82.1vol.%BCC matrix and 17.9vol.%FCC phase.Wherein the FCC phase is distributed on the BCC matrix,forming a structure where the hard BCC matrix is surrounded by soft FCC phase.This results in a hindering effect on the propagation process of vibration waves.The damping performance of Al0.54CrFe_(3)Ni alloy,characterized by an internal friction of Q^(-1) is as high as 0.059,is higher than that of most FeCr damping alloys.The volume fraction of the BCC phase and the peculiar distribution of the FCC phase are identified as the key factors affecting the damping capacity.In addition,the Al0.54CrFe3Ni alloy exhibits a high yield strength of 811.16 MPa.展开更多
The concept of grain boundary engineering(GBE)has been successfully applied to L1_(2)-strengthened(CoCrNi)_(94)Al_(3)Ti_(3)medium entropy alloy,with the aim of improving the oxidation resistance by increasing the rati...The concept of grain boundary engineering(GBE)has been successfully applied to L1_(2)-strengthened(CoCrNi)_(94)Al_(3)Ti_(3)medium entropy alloy,with the aim of improving the oxidation resistance by increasing the ratio of special boundaries and suppressing discontinuous precipitation.Surprisingly,our results reveal that GBE treatment not only slows down the oxidation kinetics and but also alters the oxide scale from TiO_(2)and multi-defect Cr_(2)O_(3)to continuous and protective Cr_(2)O_(3)and Al_(2)O_(3),thereby contributing to an enhanced oxidation and anti-spalling resistance.The GBE treatment reduces the oxidation weight gain of the current alloy from 1.950 mg cm^(-2)to 1.211 mg cm^(-2)after 100 h of cyclic oxidation at 800℃.The findings show that the extensive outward diffusion of Ti accelerates ion transport and promotes microporosity,thus leading to more defects being formed in the oxide film.The GBE treatment suppresses the discontinuous precipitation of the Ti-bearing L1_(2)phase and breaks the random large angular grain boundaries network,inhibiting the diffusion of Ti and ultimately enhancing the oxidation properties of the alloy.The current work provides an idea of oxidation resistance enhancement for Ti-bearing LI_(2)-strengthened alloys without changing the alloy composition.展开更多
Sodium superionic conductors(NASICONs)have attracted enormous attention owing to their excellent ionic diffusion and structural stability.However,the high cost of vanadium,limited capacity due to fewer redox reactions...Sodium superionic conductors(NASICONs)have attracted enormous attention owing to their excellent ionic diffusion and structural stability.However,the high cost of vanadium,limited capacity due to fewer redox reactions,and low electronic conductivity restrict their practical application.Herein,we designed Na_(3.5)V_(0.5)Mn_(0.5)Fe_(0.5)Ti_(0.5)(PO_(4))3 (NVMFTP)medium entropy NASICON with multi-electron reactions as a fast sodium storage cathode for sodium-ion batteries(SIBs).The incorporation of Fe,Mn and Ti not only reduces the cost but also activates multi-redox reactions of V^(2+)/V^(3+),Ti^(3+)/Ti^(4+),Fe^(2+)/Fe^(3+),V^(3+)/V^(4+),Mn^(2+)/Mn^(3+),V^(4+)/V^(5+).Owing to distinctive structural design with medium entropy,the NVMFTP delivered 168 mAh·g^(−1) at 0.5C with a remarkable rate capability of 93.51 mAh·g^(−1) at 60C and steady long-term cycling performance till 5000 cycles.More importantly,NVMFTP takes only 11 min to achieve 80%SOC at 5C.The in-situ and ex-situ X-ray diffraction(XRD)further demonstrate reversible multi-electron reaction mechanisms of slow charging and fast charging.NVMFTP/HC full cell shows 110 mAh·g^(−1) capacity and 208 Wh·kg^(−1) energy density.This study will provide comprehensive insight into developing low-cost,cutting-edge materials for SIBs.展开更多
The microstructural evolution,mechanical properties,and wear behavior of medium manganese steels(MMSs)with varying aluminum(Al)contents were investigated.It was observed that the microstructure of MMS transferred from...The microstructural evolution,mechanical properties,and wear behavior of medium manganese steels(MMSs)with varying aluminum(Al)contents were investigated.It was observed that the microstructure of MMS transferred from a predominantly martensitic phase(in the Al-free state)to a ferrite/martensite or ferrite/austenite duplex structure with increasing Al content.The hardness of MMS decreased with Al addition,while the impact absorbed energy and yield strength were optimized in 2%Al-containing variant.Frictional wear tests demonstrated that 2 wt.%Al-MMS exhibited superior wear resistance due to the twinning-induced plasticity effect.Conversely,under impact abrasion wear conditions,the Al-free MMS displayed the lowest mass loss,attributing to high surface hardness and remarkable work hardening capacity.These findings indicates that Al content-tailored MMSs can be selectively applied in different wear environments,with 2 wt.%Al-MMS being optimal for static load conditions and the Al-free MMS for dynamic impact abrasion scenarios.展开更多
The impact of various initial states on the ultimate mechanical properties of medium Mn steel(MMnS)following the hot stamping process is revealed.MMnS blanks with three typical initial states were prepared separately,...The impact of various initial states on the ultimate mechanical properties of medium Mn steel(MMnS)following the hot stamping process is revealed.MMnS blanks with three typical initial states were prepared separately,including hot-rolled,cold-rolled and cold-rolled and annealed(CRA).Their microstructures were observed and analyzed by scanning electron microscopy and electron backscatter diffraction,and their mechanical properties were measured by tensile tests following hot stamping and baking treatments.The results reveal that the microstructure of martensite and residual austenite characterizes the hot-stamped MMnS across different rolling conditions,with CRA state exhibiting a clearly higher residual austenite content compared to the other two states.Meanwhile,CRA state boasts not only the highest tensile strength but also the greatest elongation post-hot stamping treatment.The superior comprehensive mechanical properties are attributed to its unique biphase structure of Mn-rich austenite and Mn-poor ferrite,which emerges in CRA state following a 12 h intercritical annealing and can be partially preserved during the hot stamping process.This structure is instrumental in achieving a higher level of residual austenite,consequently leading to enhanced elongation.展开更多
The multiple oligopeptides have been regarded as promising alignment media due to their structural diverseness and tendency for self-assembly in solution.Herein,an assembled amphiphilic peptide alignment medium,i.e.,C...The multiple oligopeptides have been regarded as promising alignment media due to their structural diverseness and tendency for self-assembly in solution.Herein,an assembled amphiphilic peptide alignment medium,i.e.,C15eCONH-Phg-Phg-IIIKK-CONH2 with un-natural amino acids for the determination of anisotropic parameters of NMR is introduced.The amphiphilic peptide can be self-assembled at low concentrations in DMSO and is stable and highly homogeneous.The NMR spectrum collected with the addition of the medium had fewer background signals.The utility of the acquired RDC data is demon-strated to determine relative configuration of three natural products,Helminthosporic acid,Estrone,and a-Santonin.展开更多
基金financially supported by Guangdong Province Basic and Applied Basic Research Fund Project(Grant No.2022B1515250009)Liaoning Provincial Natural Science Foundation-Doctoral Research Start-up Fund Project(Grant No.2024-BSBA-05)+1 种基金Major Science and Technology Innovation Project in Shandong Province(Grant No.2024CXGC010803)the National Natural Science Foundation of China(Grant Nos.52271269 and 12302147).
文摘The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly complex layout combinations.Furthermore,due to constraints in component quantity and geometry within the cross-sectional layout,filler bodies must be incorporated to maintain cross-section performance.Conventional design approaches based on manual experience suffer from inefficiency,high variability,and difficulties in quantification.This paper presents a multi-level automatic filling optimization design method for umbilical cross-sectional layouts to address these limitations.Initially,the research establishes a multi-objective optimization model that considers compactness,balance,and wear resistance of the cross-section,employing an enhanced genetic algorithm to achieve a near-optimal layout.Subsequently,the study implements an image processing-based vacancy detection technique to accurately identify cross-sectional gaps.To manage the variability and diversity of these vacant regions,the research introduces a multi-level filling method that strategically selects and places filler bodies of varying dimensions,overcoming the constraints of uniform-size fillers.Additionally,the method incorporates a hierarchical strategy that subdivides the complex cross-section into multiple layers,enabling layer-by-layer optimization and filling.This approach reduces manufac-turing equipment requirements while ensuring practical production process feasibility.The methodology is validated through a specific umbilical case study.The results demonstrate improvements in compactness,balance,and wear resistance compared with the initial cross-section,offering novel insights and valuable references for filler design in umbilical cross-sections.
基金National Natural Science Foundation of China(Nos.42301473,42271424,42171397)Chinese Postdoctoral Innovation Talents Support Program(No.BX20230299)+2 种基金China Postdoctoral Science Foundation(No.2023M742884)Natural Science Foundation of Sichuan Province(Nos.24NSFSC2264,2025ZNSFSC0322)Key Research and Development Project of Sichuan Province(No.24ZDYF0633).
文摘As a key node of modern transportation network,the informationization management of road tunnels is crucial to ensure the operation safety and traffic efficiency.However,the existing tunnel vehicle modeling methods generally have problems such as insufficient 3D scene description capability and low dynamic update efficiency,which are difficult to meet the demand of real-time accurate management.For this reason,this paper proposes a vehicle twin modeling method for road tunnels.This approach starts from the actual management needs,and supports multi-level dynamic modeling from vehicle type,size to color by constructing a vehicle model library that can be flexibly invoked;at the same time,semantic constraint rules with geometric layout,behavioral attributes,and spatial relationships are designed to ensure that the virtual model matches with the real model with a high degree of similarity;ultimately,the prototype system is constructed and the case region is selected for the case study,and the dynamic vehicle status in the tunnel is realized by integrating real-time monitoring data with semantic constraints for precise virtual-real mapping.Finally,the prototype system is constructed and case experiments are conducted in selected case areas,which are combined with real-time monitoring data to realize dynamic updating and three-dimensional visualization of vehicle states in tunnels.The experiments show that the proposed method can run smoothly with an average rendering efficiency of 17.70 ms while guaranteeing the modeling accuracy(composite similarity of 0.867),which significantly improves the real-time and intuitive tunnel management.The research results provide reliable technical support for intelligent operation and emergency response of road tunnels,and offer new ideas for digital twin modeling of complex scenes.
基金financially supported by the National Natural Science Foundation of China(Nos.52074078 and 52374327)the Applied Fundamental Research Program of Liaoning Province,China(No.2023JH2/101600002)+3 种基金the Liaoning Provincial Natural Science Foundation,China(No.2022-YQ-09)the Shenyang Young Middle-Aged Scientific and Technological Innovation Talent Support Program,China(No.RC220491)the Liaoning Province Steel Industry-University-Research Innovation Alliance Cooperation Project of Bensteel Group,China(No.KJBLM202202)the Fundamental Research Funds for the Central Universities,China(Nos.N2201023 and N2325009)。
文摘In recent years,medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances.By controlling reasonable elemental composition and processing parameters,the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower costs.In this paper,a FeCoNi medium entropy alloy precursor was prepared via sol-gel and coprecipitation methods,respectively,and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen reduction.The phases and magnetic properties of FeCoNi medium entropy alloy were investigated.Results showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500℃.Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal reduction.The alloy prepared by hydrogen reduction was uniform and showed a relatively high purity.Moreover,the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.
基金financial support from the National Natural Science Foundation of China(Nos.52233018 and 51831002)the China Baowu Low Carbon Metallurgy Innovation Foudation(No.BWLCF202213)。
文摘The influence of Nb-V microalloying on the hot deformation behavior and microstructures of medium Mn steel(MMS)was investigated by uniaxial hot compression tests.By establishing the constitutive equations for simulating the measured flow curves,we successfully constructed deformation activation energy(Q)maps and processing maps for identifying the region of flow instability.We concluded the following consequences of Nb-V alloying for MMS.(i)The critical strain increases and the increment diminishes with the increasing deformation temperature,suggesting that NbC precipitates more efficiently retard dynamic recrystallization(DRX)in MMS compared with solute Nb.(ii)The deformation activation energy of MMS is significantly increased and even higher than that of some reported high Mn steels,suggesting that its ability to retard DRX is greater than that of the high Mn content.(iii)The hot workability of MMS is improved by narrowing the hot processing window for the unstable flow stress,in which fine recrystallized and coarse unrecrystallized grains are present.
基金funding from the National Natural Science Foundation of China(Nos.52063017 and 52061025)the Major Science and Technology Project of Gansu Province(Nos.22ZD6GA008 and 20ZD7GJ008)+3 种基金the Natural Science Foundation of Gansu Province(No.23JRRA820)The Science and Technology Project of Major Science and Technology Project of Gansu Province(No.22ZD6GA008)the Science and Technology Project of Gansu Province(No.23YFGA0058)the College Industry Support Plan of Gansu Province(No.2023CYZC-27).
文摘The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (H/MEAs) still lacks effective atomic-scale composition design and screening schemes, which hinders the accurate prediction of desired composition and properties. This study proposes a novel approach for rapidly designing the composition of materials with the aim of overcoming the trade-off between strength and ductility in metal matrix composites. The effect of chemical composition on stacking fault energy (SFE), shear modulus, and phase stability was investigated through the use of molecular dynamics (MD) and thermodynamic calculation software. The alloy's low SFE, highest shear modulus, and stable face-centered cubic (FCC) phase have been identified as three standard physical quantities for rapid screening to characterize the deformation mechanism, ultimate tensile strength, phase stability, and ductility of the alloy. The calculation results indicate that the optimal composition space is expected to fall within the ranges of 17 %–34 % Ni, 33 %–50 % Co, and 25 %–33 % Mn. The comparison of stress-strain curves for various predicted components using simulated and experimental results serves to reinforce the efficacy of the method. This indicates that the screening criteria offer a necessary design concept, deviating from traditional strategies and providing crucial guidance for the rapid development and application of MEAs.
基金supported by the National Key R&D Program of China(No.2024YFB4007501)the Natural Science Foundation of Jiangsu Province(No.BK20240109)the project of Jiangsu Key Laboratory for Clean Utilization of Carbon Resources(No.BM2024007).
文摘Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxide fuel cells(SOFCs)represents an efficient and promising strategy for its effective utilization.However,direct application in Ni-based anodes induces carbon deposition,which severely degrades cell performance.Herein,a medium-entropy oxide Sr_(2)FeNi_(0.1)Cr_(0.3)Mn_(0.3)Mo_(0.3)O_(6−δ)(SFNCMM)was developed as an anode internal reforming catalyst.Following reduction treatment,FeNi_(3) nano-alloy particles precipitate on the surface of the material,thereby significantly enhancing its catalytic activity for LC-CMM reforming process.The catalyst achieved a methane conversion rate of 53.3%,demonstrating excellent catalytic performance.Electrochemical evaluations revealed that SFNCMM-Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)with a weight ratio of 7:3 exhibited superior electrochemical performance when employed as the anodic catalytic layer.With H_(2) and LC-CMM as fuels,the single cell achieved maximum power densities of 1467.32 and 1116.97 mW·cm^(−2) at 800℃,respectively,with corresponding polarization impedances of 0.17 and 1.35Ω·cm^(2).Furthermore,the single cell maintained stable operation for over 100 h under LC-CMM fueling without significant carbon deposition,confirming its robust resistance to carbon formation.These results underscore the potential of medium-entropy oxides as highly effective catalytic layers for mitigating carbon deposition in SOFCs.
文摘BACKGROUND Oil-based iodinated contrast media have excellent contrast properties and are widely used for hysterosalpingographic evaluation of female infertility.On abdominal radiography and computed tomography(CT)scans,their radiodensity is similar to that of metallic objects,which can sometimes lead to diagnostic confusion in the postoperative settings.In this case,retained oil-based contrast medium was observed on an abdominal radiograph following a cesarean section,making it difficult to differentiate from an intraperitoneal foreign body from surgery.The patient was a 37-year-old pregnant woman who was referred to our hospital at 32 weeks and 1 day of pregnancy due to complete placenta previa for mana-gement of pregnancy and delivery.An elective cesarean section was performed at 37 weeks and 3 days.A plain abdominal radiograph taken immediately after surgery revealed a near-round,hyperdense,mass-like shadow with a regular margin in the pelvic cavity.An intraperitoneal foreign body was suspected;therefore,an abdominal CT scan was performed.The foreign body was located on the left side of the pouch of Douglas and had a CT value of 7000 Hounsfield units,similar to that of metals.The CT value strongly suggested the presence of an artificial object.However,further inquiries with the patient and her previous physician revealed a history of hysterosalpingography.Accordingly,retained oil-based iodinated contrast medium was suspected,and observation of the object’s course was adopted.CONCLUSION When intraperitoneal foreign bodies are suspected on postoperative radiographs,the possibility of oil-based iodinated contrast medium retention should be considered.
基金Supported by the Inner Mongolia Autonomous Region's Key Research and Achievement Transformation Plan(2025YFSH0029).
文摘[Objectives]To evaluate the performance of two rapid chromogenic media for the detection of Bacillus cereus in milk powder,and verify the media's inclusivity,exclusivity,and accuracy,and to assess their applicability for the quantitative detection of B.cereus.[Methods]B.cereus in milk powder samples was quantified using two rapid chromogenic media in combination with the national standard method.Agreement between the quantitative results from the three methods was subsequently assessed for agreement via a paired t-test.[Results]No significant differences were observed between the bacterial counts yielded by the two rapid chromogenic media and the national standard method(P>0.05),with excellent agreement between them.[Conclusions]The method of rapid chromogenic culture medium is rapid and simple.
基金the funding support from the National Natural Science Foundation of China(Grant No.52308340)Chongqing Talent Innovation and Entrepreneurship Demonstration Team Project(Grant No.cstc2024ycjh-bgzxm0012)the Science and Technology Projects supported by China Coal Technology and Engineering Chongqing Design and Research Institute(Group)Co.,Ltd.(Grant No.H20230317).
文摘Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,there is limited research on the spatiotemporal characteristics of landslide deformation.This paper proposes a novel Multi-Relation Spatiotemporal Graph Residual Network with Multi-Level Feature Attention(MFA-MRSTGRN)that effectively improves the prediction performance of landslide displacement through spatiotemporal fusion.This model integrates internal seepage factors as data feature enhancements with external triggering factors,allowing for accurate capture of the complex spatiotemporal characteristics of landslide displacement and the construction of a multi-source heterogeneous dataset.The MFA-MRSTGRN model incorporates dynamic graph theory and four key modules:multilevel feature attention,temporal-residual decomposition,spatial multi-relational graph convolution,and spatiotemporal fusion prediction.This comprehensive approach enables the efficient analyses of multi-source heterogeneous datasets,facilitating adaptive exploration of the evolving multi-relational,multi-dimensional spatiotemporal complexities in landslides.When applying this model to predict the displacement of the Liangshuijing landslide,we demonstrate that the MFA-MRSTGRN model surpasses traditional models,such as random forest(RF),long short-term memory(LSTM),and spatial temporal graph convolutional networks(ST-GCN)models in terms of various evaluation metrics including mean absolute error(MAE=1.27 mm),root mean square error(RMSE=1.49 mm),mean absolute percentage error(MAPE=0.026),and R-squared(R^(2)=0.88).Furthermore,feature ablation experiments indicate that incorporating internal seepage factors improves the predictive performance of landslide displacement models.This research provides an advanced and reliable method for landslide displacement prediction.
基金funded by the Ministry of Education of the Russian Federation within the framework of a state assignment,number 1023032300071-6-2.3.1.
文摘The dynamics of fluid and non-buoyant particles in a librating horizontal annulus is studied experimentally.In the absence of librations,the granular material forms a cylindrical layer near the outer boundary of the annulus and undergoes rigid-body rotation with the fluid and the annulus.It is demonstrated that the librational liquefaction of the granular material results in pattern formation.This self-organization process stems from the excitation of inertial modes induced by the oscillatory motion of liquefied granular material under the influence of the gravitational force.The inertial wave induces vortical fluid flow which entrains particles from rest and forms eroded areas that are equidistant from each other along the axis of rotation.Theoretical analysis and experiments demonstrate that a liquefied layer of granular material oscillates with a radian frequency equal to the angular velocity of the annulus and interacts with the inertial wave it excites.The new phenomenon of libration-induced pattern formation is of practical interest as it can be used to control multiphase flows and mass transfer in rotating containers in a variety of industrial processes.
基金co-supported by the National Key Research and Development Program of China(No.2022YFF0503100)the Youth Innovation Project of Pandeng Program of National Space Science Center,Chinese Academy of Sciences(No.E3PD40012S).
文摘As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could range from kilometers to tens of kilometers, and even hundreds and thousands of kilometers. Therefore, it is crucial to develop effective long-range path planning for lunar rovers to meet the demands of lunar patrol exploration. This paper presents a hierarchical map model path planning method that utilizes the existing high-resolution images, digital elevation models and mineral abundance maps. The objective is to address the issue of the construction of lunar rover travel costs in the absence of large-scale, high-resolution digital elevation models. This method models the reference and semantic layers using the middle- and low-resolution remote sensing data. The multi-scale obstacles on the lunar surface are extracted by combining the deep learning algorithm on the high-resolution image, and the obstacle avoidance layer is modeled. A two-stage exploratory path planning decision is employed for long-distance driving path planning on a global–local scale. The proposed method analyzes the long-distance accessibility of various areas of scientific significance, such as Rima Bode. A high-precision digital elevation model is created using stereo images to validate the method. Based on the findings, it can be observed that the entire route spans a distance of 930.32 km. The route demonstrates an impressive ability to avoid meter-level impact craters and linear structures while maintaining an average slope of less than 8°. This paper explores scientific research by traversing at least seven basalt units, uncovering the secrets of lunar volcanic activities, and establishing ‘golden spike’ reference points for lunar stratigraphy. The final result of path planning can serve as a valuable reference for the design, mission demonstration, and subsequent project implementation of the new manned lunar rover.
文摘Thyroid nodules,a common disorder in the endocrine system,require accurate segmentation in ultrasound images for effective diagnosis and treatment.However,achieving precise segmentation remains a challenge due to various factors,including scattering noise,low contrast,and limited resolution in ultrasound images.Although existing segmentation models have made progress,they still suffer from several limitations,such as high error rates,low generalizability,overfitting,limited feature learning capability,etc.To address these challenges,this paper proposes a Multi-level Relation Transformer-based U-Net(MLRT-UNet)to improve thyroid nodule segmentation.The MLRTUNet leverages a novel Relation Transformer,which processes images at multiple scales,overcoming the limitations of traditional encoding methods.This transformer integrates both local and global features effectively through selfattention and cross-attention units,capturing intricate relationships within the data.The approach also introduces a Co-operative Transformer Fusion(CTF)module to combine multi-scale features from different encoding layers,enhancing the model’s ability to capture complex patterns in the data.Furthermore,the Relation Transformer block enhances long-distance dependencies during the decoding process,improving segmentation accuracy.Experimental results showthat the MLRT-UNet achieves high segmentation accuracy,reaching 98.2% on the Digital Database Thyroid Image(DDT)dataset,97.8% on the Thyroid Nodule 3493(TG3K)dataset,and 98.2% on the Thyroid Nodule3K(TN3K)dataset.These findings demonstrate that the proposed method significantly enhances the accuracy of thyroid nodule segmentation,addressing the limitations of existing models.
基金supported by the Fund of Key Laboratory of Biomedical Engineering of Hainan Province(No.BME20240001)the STI2030-Major Projects(No.2021ZD0200104)the National Natural Science Foundations of China under Grant 61771437.
文摘Deep learning networks are increasingly exploited in the field of neuronal soma segmentation.However,annotating dataset is also an expensive and time-consuming task.Unsupervised domain adaptation is an effective method to mitigate the problem,which is able to learn an adaptive segmentation model by transferring knowledge from a rich-labeled source domain.In this paper,we propose a multi-level distribution alignment-based unsupervised domain adaptation network(MDA-Net)for segmentation of 3D neuronal soma images.Distribution alignment is performed in both feature space and output space.In the feature space,features from different scales are adaptively fused to enhance the feature extraction capability for small target somata and con-strained to be domain invariant by adversarial adaptation strategy.In the output space,local discrepancy maps that can reveal the spatial structures of somata are constructed on the predicted segmentation results.Then thedistribution alignment is performed on the local discrepancies maps across domains to obtain a superior discrepancy map in the target domain,achieving refined segmentation performance of neuronal somata.Additionally,after a period of distribution align-ment procedure,a portion of target samples with high confident pseudo-labels are selected as training data,which assist in learning a more adaptive segmentation network.We verified the superiority of the proposed algorithm by comparing several domain adaptation networks on two 3D mouse brain neuronal somata datasets and one macaque brain neuronal soma dataset.
基金supported by the National Natural Science Foundation of China(No.51904188)the China Postdoctoral Science Foundation Funded Project(No.2024M763564)the Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province(No.ZJRMG-2022-03)。
文摘The energy-focusing blast is an innovative and ingenious method to achieve directional fracturing.Understanding its energy regulation mechanism is critical to enhancing its practical effectiveness.This study investigates the energy regulation mechanism and explores the medium-filling effects within the energy-focusing blast by employing theoretical analysis,numerical simulations,and model tests.The findings by theoretical and numerical analysis first reveal that two stages of the fracturing and tensile stage govern the directionally crack propagation,in which the explosion energy in the non-energyfocusing direction is suppressed,compressing the borehole wall,while redirected energy produces tensile stress in the energy-focusing direction,driving the formation of directional cracks.The choice of filling medium significantly affects directional cracking due to its impact on energy distribution and regulation,and key properties such as wave impedance and compressibility of the filling medium are critical.Experimental comparisons using air,sand,and water as filling media further disclose the distinct effects of the medium on energy regulation and directional crack growth of the energy-focusing blast.The maximum shaped-energy coefficients for air,sand,and water are 1.30,4.41,and 6.12 in the energy-focusing direction,respectively.Meanwhile,the stress attenuation rate of air,sand,and water increases in that order.The higher wave impedance and lower compressibility of water support efficient and uniform energy propagation,which subtly enhances the tensile actions in the focusing direction and intensifies the overall stress impact of the energy-focusing blast.In addition,the stresses in the non-energyfocusing directions decrease as the angle from the energy-focusing direction increases,while the stresses are relatively uniform for both air and water but noticeably uneven for sand;meanwhile,the fractal dimensions of blasting cracks in the case of air,water,and sand are 1.076,1.068,and 1.112,respectively.Sand as a filling medium leads to increased crack irregularities due to its granularity and heterogeneity.The water medium strikes an optimal balance by promoting the blasting energy transition and optimizing the energy distribution,maintaining the least flatness of the directional crack during energy-focusing blasts.
基金supported by the Natural Science Foundation of Liaoning Province(No.2022-BS-181).
文摘The phase constitution,microstructure,damping capacity,and mechanical properties of as-cast AlxCrFe3Ni(x=0.5,0.52,0.54,and 0.56,respectively)medium entropy alloys were investigated.It is found that the volume fraction of BCC phase increases while that of FCC decreases with increasing the Al content.When the content of Al is 0.54,the alloy is composed of 82.1vol.%BCC matrix and 17.9vol.%FCC phase.Wherein the FCC phase is distributed on the BCC matrix,forming a structure where the hard BCC matrix is surrounded by soft FCC phase.This results in a hindering effect on the propagation process of vibration waves.The damping performance of Al0.54CrFe_(3)Ni alloy,characterized by an internal friction of Q^(-1) is as high as 0.059,is higher than that of most FeCr damping alloys.The volume fraction of the BCC phase and the peculiar distribution of the FCC phase are identified as the key factors affecting the damping capacity.In addition,the Al0.54CrFe3Ni alloy exhibits a high yield strength of 811.16 MPa.
基金the National Natural Science Foundation of China(Nos.U1908219,52171163)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-2)+2 种基金the National key Research&Development Program of China(No.2022YFF0609002)the Natural Science Foundation of Liaoning Province(No.2022-BS-001)China Postdoctoral Science Foundation(No.2022M713210)。
文摘The concept of grain boundary engineering(GBE)has been successfully applied to L1_(2)-strengthened(CoCrNi)_(94)Al_(3)Ti_(3)medium entropy alloy,with the aim of improving the oxidation resistance by increasing the ratio of special boundaries and suppressing discontinuous precipitation.Surprisingly,our results reveal that GBE treatment not only slows down the oxidation kinetics and but also alters the oxide scale from TiO_(2)and multi-defect Cr_(2)O_(3)to continuous and protective Cr_(2)O_(3)and Al_(2)O_(3),thereby contributing to an enhanced oxidation and anti-spalling resistance.The GBE treatment reduces the oxidation weight gain of the current alloy from 1.950 mg cm^(-2)to 1.211 mg cm^(-2)after 100 h of cyclic oxidation at 800℃.The findings show that the extensive outward diffusion of Ti accelerates ion transport and promotes microporosity,thus leading to more defects being formed in the oxide film.The GBE treatment suppresses the discontinuous precipitation of the Ti-bearing L1_(2)phase and breaks the random large angular grain boundaries network,inhibiting the diffusion of Ti and ultimately enhancing the oxidation properties of the alloy.The current work provides an idea of oxidation resistance enhancement for Ti-bearing LI_(2)-strengthened alloys without changing the alloy composition.
基金supported by the National Natural Science Foundation of China(Nos.52027801 and 92263203)the National Key R&D Program of China(Nos.2022YFA1203902 and 2022YFA1200093)and the China-Germany Collaboration Project(No.M-0199)。
文摘Sodium superionic conductors(NASICONs)have attracted enormous attention owing to their excellent ionic diffusion and structural stability.However,the high cost of vanadium,limited capacity due to fewer redox reactions,and low electronic conductivity restrict their practical application.Herein,we designed Na_(3.5)V_(0.5)Mn_(0.5)Fe_(0.5)Ti_(0.5)(PO_(4))3 (NVMFTP)medium entropy NASICON with multi-electron reactions as a fast sodium storage cathode for sodium-ion batteries(SIBs).The incorporation of Fe,Mn and Ti not only reduces the cost but also activates multi-redox reactions of V^(2+)/V^(3+),Ti^(3+)/Ti^(4+),Fe^(2+)/Fe^(3+),V^(3+)/V^(4+),Mn^(2+)/Mn^(3+),V^(4+)/V^(5+).Owing to distinctive structural design with medium entropy,the NVMFTP delivered 168 mAh·g^(−1) at 0.5C with a remarkable rate capability of 93.51 mAh·g^(−1) at 60C and steady long-term cycling performance till 5000 cycles.More importantly,NVMFTP takes only 11 min to achieve 80%SOC at 5C.The in-situ and ex-situ X-ray diffraction(XRD)further demonstrate reversible multi-electron reaction mechanisms of slow charging and fast charging.NVMFTP/HC full cell shows 110 mAh·g^(−1) capacity and 208 Wh·kg^(−1) energy density.This study will provide comprehensive insight into developing low-cost,cutting-edge materials for SIBs.
基金supported by the Guangxi Major Science and Technology Project(AB24010120)Young Talent Support Project of Guangzhou Association for Science and Technology(QT-2024-047)+3 种基金Key-Area Research and Development Program of Jiangxi Province(20243BBG71023)GDAS'Project of Science and Technology Development(2023GDASQNRC-0205 and 2024GDASZH-2024010102)Evaluation Project of Guangdong Provincial Key Laboratory(2023B1212060043)Young Elite Scientists Sponsorship Program by CAST(2022QNRC001).
文摘The microstructural evolution,mechanical properties,and wear behavior of medium manganese steels(MMSs)with varying aluminum(Al)contents were investigated.It was observed that the microstructure of MMS transferred from a predominantly martensitic phase(in the Al-free state)to a ferrite/martensite or ferrite/austenite duplex structure with increasing Al content.The hardness of MMS decreased with Al addition,while the impact absorbed energy and yield strength were optimized in 2%Al-containing variant.Frictional wear tests demonstrated that 2 wt.%Al-MMS exhibited superior wear resistance due to the twinning-induced plasticity effect.Conversely,under impact abrasion wear conditions,the Al-free MMS displayed the lowest mass loss,attributing to high surface hardness and remarkable work hardening capacity.These findings indicates that Al content-tailored MMSs can be selectively applied in different wear environments,with 2 wt.%Al-MMS being optimal for static load conditions and the Al-free MMS for dynamic impact abrasion scenarios.
基金supported by the National Key R&D Program of China(No.2022YFE0196600)the National Natural Science Foundation of China(No.52175349)the Shanghai Oriental Talent Program(No.BJKJ2024016).
文摘The impact of various initial states on the ultimate mechanical properties of medium Mn steel(MMnS)following the hot stamping process is revealed.MMnS blanks with three typical initial states were prepared separately,including hot-rolled,cold-rolled and cold-rolled and annealed(CRA).Their microstructures were observed and analyzed by scanning electron microscopy and electron backscatter diffraction,and their mechanical properties were measured by tensile tests following hot stamping and baking treatments.The results reveal that the microstructure of martensite and residual austenite characterizes the hot-stamped MMnS across different rolling conditions,with CRA state exhibiting a clearly higher residual austenite content compared to the other two states.Meanwhile,CRA state boasts not only the highest tensile strength but also the greatest elongation post-hot stamping treatment.The superior comprehensive mechanical properties are attributed to its unique biphase structure of Mn-rich austenite and Mn-poor ferrite,which emerges in CRA state following a 12 h intercritical annealing and can be partially preserved during the hot stamping process.This structure is instrumental in achieving a higher level of residual austenite,consequently leading to enhanced elongation.
基金supported by the National Natural Science Foundation of China(21874158)the Science and Technology Major Program of Gansu Province of China(22ZD6FA006 and 23ZDFA015)+1 种基金We are also grateful for the financial support from the Science and Technology Program of Henan Province(232102311180)the foundation for the University Young Key Teacher of Henan Province(2024GGJS116).
文摘The multiple oligopeptides have been regarded as promising alignment media due to their structural diverseness and tendency for self-assembly in solution.Herein,an assembled amphiphilic peptide alignment medium,i.e.,C15eCONH-Phg-Phg-IIIKK-CONH2 with un-natural amino acids for the determination of anisotropic parameters of NMR is introduced.The amphiphilic peptide can be self-assembled at low concentrations in DMSO and is stable and highly homogeneous.The NMR spectrum collected with the addition of the medium had fewer background signals.The utility of the acquired RDC data is demon-strated to determine relative configuration of three natural products,Helminthosporic acid,Estrone,and a-Santonin.
