The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect,while at low velocities,the strength effect becomes predominant.In the latter regime,mate...The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect,while at low velocities,the strength effect becomes predominant.In the latter regime,material strength dictates the resistance to plastic deformation and flow,a contrast to the shockwave-dominated interactions where compressibility is key.This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets.An integrated approach where the axial and radial dynamics are coupled has been proposed,influencing each other through shared physical principles rather than being treated as separate,empirically linked phenomena.The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine-Hugoniot relation.These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface,providing a robust physical basis for the penetration model.Notably,it considers the target material's compressibility,which elevates the pressure at the jet-target interface beyond that observed with incompressible materials.This pressure increase is directly proportional to the target's degree of compressibility.As such,this model of compressible penetration reorients the analytical approach:rather than merely estimating penetration resistance,it determines this value from the target material's specific compressibility and yield strength.This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power,particularly for novel target materials or engagement conditions outside established experimental datasets.This investigation establishes a quantitative link between the material's yield strength and its penetration resistance.The accuracy of this penetration resistance value is paramount,as it significantly influences the predicted crater diameter;indeed,the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination.Ultimately,by integrating the yield strength of the target material,this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet.The theory's validation involved two experimental sets:the first focused on shaped charge jet penetration into 45#steel at varied stand-offs,while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete(RPC)with differing strength characteristics.These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys,where plastic flow is significant,and advanced quasi-brittle cementitious composites,presenting a broad spectrum of material responses and penetration challenges.Resulting hole profiles derived from theoretical calculations demonstrated a strong correspondence with empirical measurements for both material types.展开更多
By analyzing core data from an offshore Gulf of Mexico reservoir and developing analytical solutions,it can be demonstrated that laboratory measurements on pore-volume compressibility include artifacts,leading to a mi...By analyzing core data from an offshore Gulf of Mexico reservoir and developing analytical solutions,it can be demonstrated that laboratory measurements on pore-volume compressibility include artifacts,leading to a misinterpretation of porosity and permeability trends.A systematic evaluation of poro-elastic changes in pore volumes(and quantifying any consequent fluid expulsion during reservoir compaction)suggests that poro-elastic relaxation may enhance fluid production rates from deep reservoirs by up to 25%.This value may be inadvertently inflated if the core samples used for pore-volume compressibility measurements suffered from handling damage.Nonetheless,poro-elastic fluid expulsion from the pores in producing reservoirs can provide additional lift and thus may enhance the recovery factor.Therefore,the possible contribution to well performance from poro-elastic production drive mechanisms ought to be carefully evaluated in reserves estimation.Reversely,injection wells may encounter poro-elastic suppression of injectivity due to elastic resistance,which would adversely affect the storage coefficient.By integrating geomechanical reservoir response with traditional fluid production models,reservoir model predictions of production under pressure depletion and injection conditions will be more accurate.The new insights reported here are essential for optimizing well performance,improving reservoir management,and extending the economic life of geological reservoirs.However,caution is warranted regarding pore-volume compressibility measurements.To what degree laboratory measurements of pore-volume compressibility measure true values or mainly record handling damage could not be conclusively settled in the present study.展开更多
1.Introduction Compared with the widely used vapor-compression refrigeration,solid-state cooling based on phase transition offers higher ef-ficiency,environmental friendliness,and smaller volume[1,2].The phase transit...1.Introduction Compared with the widely used vapor-compression refrigeration,solid-state cooling based on phase transition offers higher ef-ficiency,environmental friendliness,and smaller volume[1,2].The phase transition of solid refrigerants can be triggered by external fields,i.e.,magnetic fields[3-5],electric fields[6,7].展开更多
Accurately modeling real network dynamics is a grand challenge in network science.The network dynamics arise from node interactions,which are shaped by network topology.Real networks tend to exhibit compact or highly ...Accurately modeling real network dynamics is a grand challenge in network science.The network dynamics arise from node interactions,which are shaped by network topology.Real networks tend to exhibit compact or highly optimized topologies.But the key problems arise:how to compress a network to best enhance its compactness,and what the compression limit of the network reflects?We abstract the topological compression of complex networks as a dynamic process of making them more compact and propose the local compression modulus that plays a key role in effective compression evolution of networks.Subsequently,we identify topological compressibility-a general property of complex networks that characterizes the extent to which a network can be compressed-and provide its approximate quantification.We anticipate that our findings and established theory will provide valuable insights into both dynamics and various applications of complex networks.展开更多
In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. A...In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. According to the concept of the compression factor and its differential equation, a stop-wave model is built. The theoretical value and the observed one are obtained by the survey data in Changchun city. The relative error between the two values is 20. 3%. The accuracy is improved 39% compared with the result from the traditional stop-wave model. The results show that the traffic flow is compressible, and the methods of research on gas compressibility is also applicable to the traffic flow. The stop-wave model obtained by the compression factor can better describe the phenomenon of the stop wave at a signalized intersection when compared with the traditional stop-wave model.展开更多
Dear Editor,The letter proposes a tensor low-rank orthogonal compression(TLOC)model for a convolutional neural network(CNN),which facilitates its efficient and highly-accurate low-rank representation.Model compression...Dear Editor,The letter proposes a tensor low-rank orthogonal compression(TLOC)model for a convolutional neural network(CNN),which facilitates its efficient and highly-accurate low-rank representation.Model compression is crucial for deploying deep neural network(DNN)models on resource-constrained embedded devices.展开更多
In GNSS-denied environments,signals of opportunity(SOP)offer an efficient and passive solution for navigation and positioning by utilizing ambient signals.Nevertheless,conventional SOP techniques face significant chal...In GNSS-denied environments,signals of opportunity(SOP)offer an efficient and passive solution for navigation and positioning by utilizing ambient signals.Nevertheless,conventional SOP techniques face significant challenges in real-time processing,especially under sub-Nyquist sampling conditions,due to high data acquisition rates and offgrid errors.To address this,this paper proposes the signal reconstruction and kernel sparse encoding(SRKSE)model,a novel general framework for high-precision parameter estimation.By combining compressed sensing with a deep unfolding network,the SRKSE model not only achieves robust signal reconstruction but also effectively reduces quantization errors.Key innovations of SRKSE include dual crossattention mechanisms for enhanced feature extraction,sinc sparse kernel encoding to minimize quantization errors,and a custom loss function for balanced optimization.With these advancements,SRKSE achieves up to a 650-fold improvement in time of arrival(TOA)estimation accuracy while operating at just 1%of the Nyquist sampling rate.The SRKSE surpasses both conventional and deep learning-based techniques in accuracy and efficiency,especially when operating under sub-Nyquist sampling conditions.Simulations and real-world experiments confirm the reliability and potential of SRKSE for real-time applications in IoT and wireless communication.展开更多
Activation pruning reduces neural network complexity by eliminating low-importance neuron activations,yet identifying the critical pruning threshold—beyond which accuracy rapidly deteriorates—remains computationally...Activation pruning reduces neural network complexity by eliminating low-importance neuron activations,yet identifying the critical pruning threshold—beyond which accuracy rapidly deteriorates—remains computationally expensive and typically requires exhaustive search.We introduce a thermodynamics-inspired framework that treats activation distributions as energy-filtered physical systems and employs the free energy of activations as a principled evaluation metric.Phase-transition-like phenomena in the free-energy profile—such as extrema,inflection points,and curvature changes—yield reliable estimates of the critical pruning threshold,providing a theoretically grounded means of predicting sharp accuracy degradation.To further enhance efficiency,we propose a renormalized free energy technique that approximates full-evaluation free energy using only the activation distribution of the unpruned network.This eliminates repeated forward passes,dramatically reducing computational overhead and achieving speedups of up to 550×for MLPs.Extensive experiments across diverse vision architectures(MLP,CNN,ResNet,MobileNet,Vision Transformer)and text models(LSTM,BERT,ELECTRA,T5,GPT-2)on multiple datasets validate the generality,robustness,and computational efficiency of our approach.Overall,this work establishes a theoretically grounded and practically effective framework for activation pruning,bridging the gap between analytical understanding and efficient deployment of sparse neural networks.展开更多
Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluat...Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluate brittleness,many fail to comprehensively account for the impacts of microstructural changes,mineralogical characteristics,and stress conditions on energy evolution during failure.This study proposes a novel approach for brittleness evaluation based on the energy evolution throughout the post-peak failure process,integrating two micromechanical mechanisms:crack propagation and frictional sliding.A new brittleness index is defined as the ratio of generated surface energy to released elastic energy,providing a unified framework for assessing both Class I and Class II mechanical behaviors.The brittleness of cyan,white,and gray sandstones was investigated under various confining pressures and moisture conditions using X-ray diffraction(XRD),scanning electron microscopy(SEM),and conventional triaxial compression(CTC)tests.The results demonstrate that brittleness decreases with increasing confining pressure,due to suppressed crack propagation,and increases under saturated conditions,as moisture enhances crack propagation.By establishing connections between mineral composition,microstructural features,and stress-induced responses,the proposed method overcame limitations of previous approaches and offered a more precise tool for evaluating rock brittleness under diverse environmental scenarios.展开更多
In this study,the shell structure of olives in nature was modeled,and a high-porosity bionic olive body-centered cubic structure(BCCO)with reinforcement structures of circular support(BCCR)and triangular support(BCCT)...In this study,the shell structure of olives in nature was modeled,and a high-porosity bionic olive body-centered cubic structure(BCCO)with reinforcement structures of circular support(BCCR)and triangular support(BCCT)with excellent mechanical properties was designed and prepared using selective laser melting technology.The surface morphology,deformation behavior,and energy absorption of BCCO were compared with those of the equivalent uniform body-centered cubic structure(BCC)and analyzed through quasi-static compression experiments and finite element analysis.The olive-shaped structure showed optimal load resistance when the radius of curvature was equal to the edge length of the lattice structure,and outperformed with a larger curvature than with a smaller curvature.With the added support structure,the energy absorption of the BCCR increased by 144.44%compared with that of the conventional BCC structure.The newly designed olive bionic structure has considerable potential for applications in various fields,such as aerospace and medical devices.展开更多
Conglomerate rock's complex and heterogeneous microstructure significantly affects its mechanical properties,especially under dynamic loading.However,research on their dynamic behavior and fracture mechanisms is l...Conglomerate rock's complex and heterogeneous microstructure significantly affects its mechanical properties,especially under dynamic loading.However,research on their dynamic behavior and fracture mechanisms is limited.Through uniaxial compression tests and split Hopkinson pressure bar(SHPB)impact tests,the dynamic compressive mechanical properties and fracture mechanisms of conglomerate rock were studied.Nanoindentation and high-resolution X-ray computed tomography were employed to analyze the micro-mechanical behavior and internal structure of the conglomerate rock.Results indicate significant differences in mechanical properties between different gravel particles and cementing materials,with initial fractures primarily distributed at the gravel-cement interfaces.The dynamic mechanical properties of conglomerate rocks exhibit a clear strain rate dependency.Based on the stress−strain curves and failure characteristics,the dynamic compressive mechanical behavior can be categorized into two types using a critical strain rate.The dynamic compressive strength,peak strain,and toughness of conglomerate rock increased with the strain rate,with the strength at 54 s−1 being 2.6 times that at 6 s−1.The dynamic compressive fracture mechanism of conglomerate rock is related to the strain rate and microstructure;at low strain rates,gravel distribution is the key factor,whereas at high strain rates,gravel content becomes critical.展开更多
This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The finding...This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The findings revealed that the addition of 5wt%CRCF yields optimal performance,with compressive strengths reaching approximately 1.83,12.59,and 42.81 MPa at 1,3,and 28 d,respectively.These values represented significant increases of 408.3%,10.0%,and 14.3%compared to the reference sample.The improvement was attributed to the synergistic effects of ultrafine CRCF particles acting as fillers and nucleation sites,as well as the high reactivity of silica gels,which promoted the formation of additional hydration gels.Microstructural analysis confirmed that CRCF addition refined pore structure,and enhanced the stiffness of C-S-H gels.Furthermore,CRCF served as a net CO_(2) sink,sequestering 0.268 kg CO_(2) per kilogram of CRCF and thereby reducing the carbon footprint of SSC.In addition,the feasibility of applying CRCF-modified SSC in cemented paste backfill(CPB)is highlighted,given the high cement-related carbon footprint of conventional CPB.When 5wt%CRCFmodified SSC was employed in CPB,its 3-d compressive strength attained over 70%of that of ordinary Portland cement(OPC),while the 28-d strength was comparable to that of OPC.The proposed binder thus provides a sustainable pathway for BW valorization,combining waste utilization,carbon sequestration,and improved engineering performance.展开更多
To improve the applicability of red mud in subgrade construction,we studied the effects of four traditional retarders,including borax,sodium hexametaphosphate,sodium gluconate,and sucrose,on the setting time,mechanica...To improve the applicability of red mud in subgrade construction,we studied the effects of four traditional retarders,including borax,sodium hexametaphosphate,sodium gluconate,and sucrose,on the setting time,mechanical properties and soil solidification of red mud-based subgrade engineered cementitious material(RCM).The mechanisms of the retarders on the hydration process of RCM were analyzed by hydration microcalorimeter,XRD,TG,and SEM-EDS.The experimental results show that four retarders have retarding effect on RCM,among which sodium gluconate and sucrose have significant retarding effect and do not have adverse effect on 28 d strength.Borax can slightly delay the setting time,and sodium hexametaphosphate has a better retarding effect,but they both reduce the 28 d strength.Microcosmic analysis shows that the retarders do not change the type of RCM hydration products,but mainly slow down the rate of hydration reaction through the adsorption and complexation or reaction of Ca^(2+)in the slurry.All the results show that the retarder has no weakening effect on the unconfined compressive strength,water stability and CBR properties of the stabilized subgrade soil based on RCM.展开更多
Dynamic disturbances with various frequencies could trigger different failure modes of deep excavations.Superimposed on this static stress are dynamic disturbances due to various dynamic vibrations,e.g.excavation blas...Dynamic disturbances with various frequencies could trigger different failure modes of deep excavations.Superimposed on this static stress are dynamic disturbances due to various dynamic vibrations,e.g.excavation blasting,blasting,tunnel boring machine(TBM)vibration,rockburst wave,earthquakes.Specifically,these dynamic sources are characterized by a wide range of wave frequencies f,resulting in differences in failure modes.A series of true-triaxial compression tests were conducted on granite to simulate the excavation-induced stress path in three-dimensional(3D)stresses.Subsequently,a dynamic disturbance with various frequencies was applied to a cuboid specimen,to reveal the behavior associated with brittle failure.The dynamic disturbance with frequencies f of 5 Hz,10 Hz,and 40 Hz generates less disturbed energy components in the granite together with higher peak strength.However,dynamic disturbances with f of 20 Hz and 30 Hz resulted in a lower peak strength;the peak strength of the rock increases sp albeit it decreases at first,then increases.This U-shaped phenomenon relates to the natural frequency of the granite under such stress conditions.Different rock lithologies consisting of diverse mineral composition,respond differently to each sensitive resonance frequency.Interestingly,the weak disturbance stress with a high frequency f and low amplitude A increases the ratio of crack damage to peak strength(scd/sp)in the granite.This leads to the inhibition of the expansion of the granite during the dynamic disturbance process.Multiple penetrating tensileeshear cracks appear in the s3-direction as the disturbance frequency f increases.展开更多
In complex geological environments,the analysis of drill cores to determine rock strength can be challenging due to the wide variability in the degree of fracturing,leading to subjectivity in the collection of represe...In complex geological environments,the analysis of drill cores to determine rock strength can be challenging due to the wide variability in the degree of fracturing,leading to subjectivity in the collection of representative samples for uniaxial compressive strength testing.This study evaluates non-destructive techniques on calcareous rocks with different tectonic deformations,including Equotip hardness,ultrasound P-wave velocity,thin section analysis,and calcimetry,integrated with photogrammetric fracture analysis.The investigated carbonate rock samples are sourced from drill cores derived from the Umbria-Marche fold and thrust belt(northern Apennines,Italy),including a gently dipping limb of an anticline,a hinge zone of an anticline,and a fault zone associated with a thrust.Fracture intensity,quantified by the P21 parameter using photogrammetric techniques on pre-loading rock samples,is assessed alongside macroscopic identification of discontinuities(such as stylolites,veins,and joints)using marker colours to monitor failures during uniaxial compression testing.Empirical correlations depicted by single and multi-linear relationships indicate a strong dependence between the mechanical and physical properties of limestones.Both Equotip and P-wave velocity are influenced by fracture intensity,but P-wave velocity varies significantly with discontinuity orientation,especially at 45°-90°.To refine uniaxial compressive strength predictions and mitigate multicollinearity,statistical approaches,including linear and multilinear regression,Principal Component Analysis and Gaussian Process Regression,were tested.Findings improve the reliability of non-destructive techniques for assessing rock strength in structurally complex settings,with implications for geotechnical applications.展开更多
We employed machine learning approaches and visualization interpretation methods to explore the influencing factors of the compressive strength of sea sand concrete to attain a better understanding of the inherent law...We employed machine learning approaches and visualization interpretation methods to explore the influencing factors of the compressive strength of sea sand concrete to attain a better understanding of the inherent laws of concrete mix design.Four models,including random forest,Cat Boost,XGBoost,and deep neural network,were trained.The experimental results demonstrate that the XGBoost model performs the best in predicting the strength of sea sand concrete.Its R^(2)value reached 0.9999,and evaluation indexes such as MAPE,RMSE,MAE,and MSE are superior to those of other models.The principal component analysis(PCA)was conducted to visually analyze the structure and distribution of the original feature data,and Pearson correlation coefficient analysis and Shapley additive explanation(SHAP)were utilized to explore the impact of input characteristics on the strength of sea sand concrete.SHAP analysis is more conducive to revealing the nonlinear effects of various characteristics on the model prediction results,especially that particle size of stone has significant impacts on the strength of sea sand concrete.In addition,experimental verification was carried out to confirm the accuracy of the optimized training model.These findings offer some insights for the future design and application of sea sand in high-performance marine and coastal infrastructure.展开更多
Photoacoustic-computed tomography is a novel imaging technique that combines high absorption contrast and deep tissue penetration capability,enabling comprehensive three-dimensional imaging of biological targets.Howev...Photoacoustic-computed tomography is a novel imaging technique that combines high absorption contrast and deep tissue penetration capability,enabling comprehensive three-dimensional imaging of biological targets.However,the increasing demand for higher resolution and real-time imaging results in significant data volume,limiting data storage,transmission and processing efficiency of system.Therefore,there is an urgent need for an effective method to compress the raw data without compromising image quality.This paper presents a photoacoustic-computed tomography 3D data compression method and system based on Wavelet-Transformer.This method is based on the cooperative compression framework that integrates wavelet hard coding with deep learning-based soft decoding.It combines the multiscale analysis capability of wavelet transforms with the global feature modeling advantage of Transformers,achieving high-quality data compression and reconstruction.Experimental results using k-wave simulation suggest that the proposed compression system has advantages under extreme compression conditions,achieving a raw data compression ratio of up to 1:40.Furthermore,three-dimensional data compression experiment using in vivo mouse demonstrated that the maximum peak signal-to-noise ratio(PSNR)and structural similarity index(SSIM)values of reconstructed images reached 38.60 and 0.9583,effectively overcoming detail loss and artifacts introduced by raw data compression.All the results suggest that the proposed system can significantly reduce storage requirements and hardware cost,enhancing computational efficiency and image quality.These advantages support the development of photoacoustic-computed tomography toward higher efficiency,real-time performance and intelligent functionality.展开更多
An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic r...An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic responses of single ammonium perchlorate(AP)/octogen(HMX)particles embedded in a hydroxyl-terminated polybutadiene(HTPB)binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar(SHPB)system.The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured.During compression,transverse cracks developed within the AP particles,and their propagation led to particle fracturing,resulting in ductile fracturing.Unlike AP,HMX generated numerous short cracks within the internal and edge regions simultaneously,leading to fragmentation and brittle fracturing.Moreover,particle damage reduced the modulus of the sample,shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation.A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles.The simulation results agreed with the experimental observations.These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface,which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.展开更多
High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their b...High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their ballistic limits.In this paper,a fiber-scale experimental method for characterizing ultrahigh strain-rate transverse compression behavior was proposed.To begin with,in order to measure the extremely low stress and strain in small specimens,the conventional Hopkinson bar was reduced to the hundred-micron scale,thereby achieving wave impedance matching with single fibers.In addition,tangential and normal laser Doppler velocimetry(LDV)methods were employed to realize non-contact,high-precision,and high-speed axial velocity measurements of micron-scale incident and transmission bars,respectively.Meanwhile,a microscopic observation system was used to facilitate the installation of miniature fiber samples.The experimental setup and procedures were introduced,and the system accuracy was verified through sample-free loading tests based on one-dimensional stress wave propagation theory.Dynamic compression experiments on Graphene-UHMWPE fibers were carried out,followed by post-compression microstructural characterization via scanning electron microscopy(SEM).Results demonstrated that successful mechanical characterization was achieved at strain rates exceeding 105,an order of magnitude higher than the previously reported maximum rates.Furthermore,during the loading process,the fibers underwent uniform compression deformation while exhibiting pronounced strain-rate effects.This method offers a novel approach for dynamic mechanical characterization of microscale single fibers,enabling the development of comprehensive strain-ratedependent material models to guide the design of advanced composites and high-performance fibers.展开更多
High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation.Among them,tungsten-based alloys demonstrate exceptional potential owing to their superior irradiat...High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation.Among them,tungsten-based alloys demonstrate exceptional potential owing to their superior irradiation resistance.Recent experimental studies have demonstrated that W-Ta-Cr-V alloys exhibit excellent irradiation resistance under helium(He)ion irradiation.However,the underlying mechanisms,especially the migration behavior of He atoms,remain unclear.In this work,the influences of uniaxial tensile and compressive strain on He migration in W-Ta-Cr-V complex alloys have been systematically studied through first-principles calculations.Our results demonstrate that He atoms preferentially occupy the tetrahedral interstitial sites,with interstitial formation energies significantly reduced compared to pure W.The introduction of Ta,Cr,and V alloying elements markedly increases the He migration barriers,effectively suppressing He diffusion.Compressive strain increases the migration barriers,inhibiting He bubbles nucleation and growth,while tensile strain decreases the barriers,facilitating bubble formation.Compared to pure W,the W-Ta-Cr-V alloys exhibit both lower He interstitial formation energies and higher migration barriers,with further enhancement under compressive strain.Specifically,compressive strain of 6%increases the He migration barrier of the W-Ta-Cr-V alloy by 0.166 e V,which further widens the difference relative to pure W.These findings provide a theoretical explanation for the superior irradiation resistance of tungsten-based alloys observed experimentally and promote the understanding of irradiation damage in these alloys under strain.展开更多
基金the Fundamental Research Funds for the Central Universities of Nanjing University of Science and Technology(CN)under Grant No.30924010803。
文摘The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect,while at low velocities,the strength effect becomes predominant.In the latter regime,material strength dictates the resistance to plastic deformation and flow,a contrast to the shockwave-dominated interactions where compressibility is key.This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets.An integrated approach where the axial and radial dynamics are coupled has been proposed,influencing each other through shared physical principles rather than being treated as separate,empirically linked phenomena.The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine-Hugoniot relation.These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface,providing a robust physical basis for the penetration model.Notably,it considers the target material's compressibility,which elevates the pressure at the jet-target interface beyond that observed with incompressible materials.This pressure increase is directly proportional to the target's degree of compressibility.As such,this model of compressible penetration reorients the analytical approach:rather than merely estimating penetration resistance,it determines this value from the target material's specific compressibility and yield strength.This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power,particularly for novel target materials or engagement conditions outside established experimental datasets.This investigation establishes a quantitative link between the material's yield strength and its penetration resistance.The accuracy of this penetration resistance value is paramount,as it significantly influences the predicted crater diameter;indeed,the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination.Ultimately,by integrating the yield strength of the target material,this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet.The theory's validation involved two experimental sets:the first focused on shaped charge jet penetration into 45#steel at varied stand-offs,while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete(RPC)with differing strength characteristics.These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys,where plastic flow is significant,and advanced quasi-brittle cementitious composites,presenting a broad spectrum of material responses and penetration challenges.Resulting hole profiles derived from theoretical calculations demonstrated a strong correspondence with empirical measurements for both material types.
基金support provided by the College of Petroleum Engineering&Geosciences(CPG)at King Fahd University of Petroleum&Minerals(KFUPM).
文摘By analyzing core data from an offshore Gulf of Mexico reservoir and developing analytical solutions,it can be demonstrated that laboratory measurements on pore-volume compressibility include artifacts,leading to a misinterpretation of porosity and permeability trends.A systematic evaluation of poro-elastic changes in pore volumes(and quantifying any consequent fluid expulsion during reservoir compaction)suggests that poro-elastic relaxation may enhance fluid production rates from deep reservoirs by up to 25%.This value may be inadvertently inflated if the core samples used for pore-volume compressibility measurements suffered from handling damage.Nonetheless,poro-elastic fluid expulsion from the pores in producing reservoirs can provide additional lift and thus may enhance the recovery factor.Therefore,the possible contribution to well performance from poro-elastic production drive mechanisms ought to be carefully evaluated in reserves estimation.Reversely,injection wells may encounter poro-elastic suppression of injectivity due to elastic resistance,which would adversely affect the storage coefficient.By integrating geomechanical reservoir response with traditional fluid production models,reservoir model predictions of production under pressure depletion and injection conditions will be more accurate.The new insights reported here are essential for optimizing well performance,improving reservoir management,and extending the economic life of geological reservoirs.However,caution is warranted regarding pore-volume compressibility measurements.To what degree laboratory measurements of pore-volume compressibility measure true values or mainly record handling damage could not be conclusively settled in the present study.
基金supported by the National Natural Science Foundation of China(Nos.52371106,52371025,52171154,51871076,52071118,and 52301223)Interdisciplinary Research Foundation of HIT(No.IR2021201)+4 种基金the Natural Science Foundation of Ningbo City(No.2023J346)supported by Zhejiang Provincial Natural Science Foundation of China(No.LQ24E010004)supported by the National Science Foundation(NSF)-Earth Sciences(No.EAR-1634415)the Department of Energy(DOE)-GeoSciences(No.DE-FG02-94ER14466)supported by DOE-BES(No.DE-AC02-06CH11357).
文摘1.Introduction Compared with the widely used vapor-compression refrigeration,solid-state cooling based on phase transition offers higher ef-ficiency,environmental friendliness,and smaller volume[1,2].The phase transition of solid refrigerants can be triggered by external fields,i.e.,magnetic fields[3-5],electric fields[6,7].
基金supported inpart by the National Natural Science Foundation of China(Grant No. 12371088)the Innovative Research Group Project of Natural Science Foundation of Hunan Provinceof China (Grant No. 2024JJ1008)in part by the Australian Research Council (ARC) through the Discovery Projects scheme (Grant No. DP220100580)。
文摘Accurately modeling real network dynamics is a grand challenge in network science.The network dynamics arise from node interactions,which are shaped by network topology.Real networks tend to exhibit compact or highly optimized topologies.But the key problems arise:how to compress a network to best enhance its compactness,and what the compression limit of the network reflects?We abstract the topological compression of complex networks as a dynamic process of making them more compact and propose the local compression modulus that plays a key role in effective compression evolution of networks.Subsequently,we identify topological compressibility-a general property of complex networks that characterizes the extent to which a network can be compressed-and provide its approximate quantification.We anticipate that our findings and established theory will provide valuable insights into both dynamics and various applications of complex networks.
基金The National Basic Research Program of China (973Pro-gram)(No.2006CB705505)
文摘In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. According to the concept of the compression factor and its differential equation, a stop-wave model is built. The theoretical value and the observed one are obtained by the survey data in Changchun city. The relative error between the two values is 20. 3%. The accuracy is improved 39% compared with the result from the traditional stop-wave model. The results show that the traffic flow is compressible, and the methods of research on gas compressibility is also applicable to the traffic flow. The stop-wave model obtained by the compression factor can better describe the phenomenon of the stop wave at a signalized intersection when compared with the traditional stop-wave model.
基金supported by the Science and Technology Innovation Key R&D Program of Chongqing(CSTB2025TIAD-STX0032)National Key Research and Development Program of China(2024YFF0908200)+1 种基金the Chongqing Technology Innovation and Application Development Special Key Project(CSTB2024TIAD-KPX0018)the Southwest University Graduate Student Research Innovation(SWUB24051)。
文摘Dear Editor,The letter proposes a tensor low-rank orthogonal compression(TLOC)model for a convolutional neural network(CNN),which facilitates its efficient and highly-accurate low-rank representation.Model compression is crucial for deploying deep neural network(DNN)models on resource-constrained embedded devices.
基金National Key Laboratory of Unmanned Aerial Vehicle Technology(No.202408)Key Laboratory of Smart Earth(No.KF2023ZD01-05)。
文摘In GNSS-denied environments,signals of opportunity(SOP)offer an efficient and passive solution for navigation and positioning by utilizing ambient signals.Nevertheless,conventional SOP techniques face significant challenges in real-time processing,especially under sub-Nyquist sampling conditions,due to high data acquisition rates and offgrid errors.To address this,this paper proposes the signal reconstruction and kernel sparse encoding(SRKSE)model,a novel general framework for high-precision parameter estimation.By combining compressed sensing with a deep unfolding network,the SRKSE model not only achieves robust signal reconstruction but also effectively reduces quantization errors.Key innovations of SRKSE include dual crossattention mechanisms for enhanced feature extraction,sinc sparse kernel encoding to minimize quantization errors,and a custom loss function for balanced optimization.With these advancements,SRKSE achieves up to a 650-fold improvement in time of arrival(TOA)estimation accuracy while operating at just 1%of the Nyquist sampling rate.The SRKSE surpasses both conventional and deep learning-based techniques in accuracy and efficiency,especially when operating under sub-Nyquist sampling conditions.Simulations and real-world experiments confirm the reliability and potential of SRKSE for real-time applications in IoT and wireless communication.
基金output of a research project implemented as part of the Basic Research Program at HSE University。
文摘Activation pruning reduces neural network complexity by eliminating low-importance neuron activations,yet identifying the critical pruning threshold—beyond which accuracy rapidly deteriorates—remains computationally expensive and typically requires exhaustive search.We introduce a thermodynamics-inspired framework that treats activation distributions as energy-filtered physical systems and employs the free energy of activations as a principled evaluation metric.Phase-transition-like phenomena in the free-energy profile—such as extrema,inflection points,and curvature changes—yield reliable estimates of the critical pruning threshold,providing a theoretically grounded means of predicting sharp accuracy degradation.To further enhance efficiency,we propose a renormalized free energy technique that approximates full-evaluation free energy using only the activation distribution of the unpruned network.This eliminates repeated forward passes,dramatically reducing computational overhead and achieving speedups of up to 550×for MLPs.Extensive experiments across diverse vision architectures(MLP,CNN,ResNet,MobileNet,Vision Transformer)and text models(LSTM,BERT,ELECTRA,T5,GPT-2)on multiple datasets validate the generality,robustness,and computational efficiency of our approach.Overall,this work establishes a theoretically grounded and practically effective framework for activation pruning,bridging the gap between analytical understanding and efficient deployment of sparse neural networks.
基金supported by the National Natural Science Foundation of China(Grant No.42277147)Ningbo Public Welfare Research Program(Grant No.2024S081)Ningbo Natural Science Foundation(Grant No.2024J186).
文摘Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluate brittleness,many fail to comprehensively account for the impacts of microstructural changes,mineralogical characteristics,and stress conditions on energy evolution during failure.This study proposes a novel approach for brittleness evaluation based on the energy evolution throughout the post-peak failure process,integrating two micromechanical mechanisms:crack propagation and frictional sliding.A new brittleness index is defined as the ratio of generated surface energy to released elastic energy,providing a unified framework for assessing both Class I and Class II mechanical behaviors.The brittleness of cyan,white,and gray sandstones was investigated under various confining pressures and moisture conditions using X-ray diffraction(XRD),scanning electron microscopy(SEM),and conventional triaxial compression(CTC)tests.The results demonstrate that brittleness decreases with increasing confining pressure,due to suppressed crack propagation,and increases under saturated conditions,as moisture enhances crack propagation.By establishing connections between mineral composition,microstructural features,and stress-induced responses,the proposed method overcame limitations of previous approaches and offered a more precise tool for evaluating rock brittleness under diverse environmental scenarios.
基金Supported by Key Technologies Research and Development Program of China(Grant No.2022YFC2406004).
文摘In this study,the shell structure of olives in nature was modeled,and a high-porosity bionic olive body-centered cubic structure(BCCO)with reinforcement structures of circular support(BCCR)and triangular support(BCCT)with excellent mechanical properties was designed and prepared using selective laser melting technology.The surface morphology,deformation behavior,and energy absorption of BCCO were compared with those of the equivalent uniform body-centered cubic structure(BCC)and analyzed through quasi-static compression experiments and finite element analysis.The olive-shaped structure showed optimal load resistance when the radius of curvature was equal to the edge length of the lattice structure,and outperformed with a larger curvature than with a smaller curvature.With the added support structure,the energy absorption of the BCCR increased by 144.44%compared with that of the conventional BCC structure.The newly designed olive bionic structure has considerable potential for applications in various fields,such as aerospace and medical devices.
基金Project(51978674)supported by the National Natural Science Foundation of China。
文摘Conglomerate rock's complex and heterogeneous microstructure significantly affects its mechanical properties,especially under dynamic loading.However,research on their dynamic behavior and fracture mechanisms is limited.Through uniaxial compression tests and split Hopkinson pressure bar(SHPB)impact tests,the dynamic compressive mechanical properties and fracture mechanisms of conglomerate rock were studied.Nanoindentation and high-resolution X-ray computed tomography were employed to analyze the micro-mechanical behavior and internal structure of the conglomerate rock.Results indicate significant differences in mechanical properties between different gravel particles and cementing materials,with initial fractures primarily distributed at the gravel-cement interfaces.The dynamic mechanical properties of conglomerate rocks exhibit a clear strain rate dependency.Based on the stress−strain curves and failure characteristics,the dynamic compressive mechanical behavior can be categorized into two types using a critical strain rate.The dynamic compressive strength,peak strain,and toughness of conglomerate rock increased with the strain rate,with the strength at 54 s−1 being 2.6 times that at 6 s−1.The dynamic compressive fracture mechanism of conglomerate rock is related to the strain rate and microstructure;at low strain rates,gravel distribution is the key factor,whereas at high strain rates,gravel content becomes critical.
基金supports from the National Natural Science Foundation of China(No.52304148)the Youth Project of Shanxi Basic Research Program(No.202203021212262).
文摘This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The findings revealed that the addition of 5wt%CRCF yields optimal performance,with compressive strengths reaching approximately 1.83,12.59,and 42.81 MPa at 1,3,and 28 d,respectively.These values represented significant increases of 408.3%,10.0%,and 14.3%compared to the reference sample.The improvement was attributed to the synergistic effects of ultrafine CRCF particles acting as fillers and nucleation sites,as well as the high reactivity of silica gels,which promoted the formation of additional hydration gels.Microstructural analysis confirmed that CRCF addition refined pore structure,and enhanced the stiffness of C-S-H gels.Furthermore,CRCF served as a net CO_(2) sink,sequestering 0.268 kg CO_(2) per kilogram of CRCF and thereby reducing the carbon footprint of SSC.In addition,the feasibility of applying CRCF-modified SSC in cemented paste backfill(CPB)is highlighted,given the high cement-related carbon footprint of conventional CPB.When 5wt%CRCFmodified SSC was employed in CPB,its 3-d compressive strength attained over 70%of that of ordinary Portland cement(OPC),while the 28-d strength was comparable to that of OPC.The proposed binder thus provides a sustainable pathway for BW valorization,combining waste utilization,carbon sequestration,and improved engineering performance.
基金Funded by the Shandong Province Key R&D Program(Major Technological Innovation Project(Nos.2023ZLGX01 and 2021CXGC010301)the Youth Project of National Natural Science Foundation(No.52309136)+1 种基金the Competitive Innovation Platform Project of Shandong Province(No.2023CXPT-080)the Postdoctoral Innovation Project(No.SDCX-ZG-202203037)。
文摘To improve the applicability of red mud in subgrade construction,we studied the effects of four traditional retarders,including borax,sodium hexametaphosphate,sodium gluconate,and sucrose,on the setting time,mechanical properties and soil solidification of red mud-based subgrade engineered cementitious material(RCM).The mechanisms of the retarders on the hydration process of RCM were analyzed by hydration microcalorimeter,XRD,TG,and SEM-EDS.The experimental results show that four retarders have retarding effect on RCM,among which sodium gluconate and sucrose have significant retarding effect and do not have adverse effect on 28 d strength.Borax can slightly delay the setting time,and sodium hexametaphosphate has a better retarding effect,but they both reduce the 28 d strength.Microcosmic analysis shows that the retarders do not change the type of RCM hydration products,but mainly slow down the rate of hydration reaction through the adsorption and complexation or reaction of Ca^(2+)in the slurry.All the results show that the retarder has no weakening effect on the unconfined compressive strength,water stability and CBR properties of the stabilized subgrade soil based on RCM.
基金supported by the National Natural Science Foundation of China(Grant Nos.52222810 and 52178383).
文摘Dynamic disturbances with various frequencies could trigger different failure modes of deep excavations.Superimposed on this static stress are dynamic disturbances due to various dynamic vibrations,e.g.excavation blasting,blasting,tunnel boring machine(TBM)vibration,rockburst wave,earthquakes.Specifically,these dynamic sources are characterized by a wide range of wave frequencies f,resulting in differences in failure modes.A series of true-triaxial compression tests were conducted on granite to simulate the excavation-induced stress path in three-dimensional(3D)stresses.Subsequently,a dynamic disturbance with various frequencies was applied to a cuboid specimen,to reveal the behavior associated with brittle failure.The dynamic disturbance with frequencies f of 5 Hz,10 Hz,and 40 Hz generates less disturbed energy components in the granite together with higher peak strength.However,dynamic disturbances with f of 20 Hz and 30 Hz resulted in a lower peak strength;the peak strength of the rock increases sp albeit it decreases at first,then increases.This U-shaped phenomenon relates to the natural frequency of the granite under such stress conditions.Different rock lithologies consisting of diverse mineral composition,respond differently to each sensitive resonance frequency.Interestingly,the weak disturbance stress with a high frequency f and low amplitude A increases the ratio of crack damage to peak strength(scd/sp)in the granite.This leads to the inhibition of the expansion of the granite during the dynamic disturbance process.Multiple penetrating tensileeshear cracks appear in the s3-direction as the disturbance frequency f increases.
文摘In complex geological environments,the analysis of drill cores to determine rock strength can be challenging due to the wide variability in the degree of fracturing,leading to subjectivity in the collection of representative samples for uniaxial compressive strength testing.This study evaluates non-destructive techniques on calcareous rocks with different tectonic deformations,including Equotip hardness,ultrasound P-wave velocity,thin section analysis,and calcimetry,integrated with photogrammetric fracture analysis.The investigated carbonate rock samples are sourced from drill cores derived from the Umbria-Marche fold and thrust belt(northern Apennines,Italy),including a gently dipping limb of an anticline,a hinge zone of an anticline,and a fault zone associated with a thrust.Fracture intensity,quantified by the P21 parameter using photogrammetric techniques on pre-loading rock samples,is assessed alongside macroscopic identification of discontinuities(such as stylolites,veins,and joints)using marker colours to monitor failures during uniaxial compression testing.Empirical correlations depicted by single and multi-linear relationships indicate a strong dependence between the mechanical and physical properties of limestones.Both Equotip and P-wave velocity are influenced by fracture intensity,but P-wave velocity varies significantly with discontinuity orientation,especially at 45°-90°.To refine uniaxial compressive strength predictions and mitigate multicollinearity,statistical approaches,including linear and multilinear regression,Principal Component Analysis and Gaussian Process Regression,were tested.Findings improve the reliability of non-destructive techniques for assessing rock strength in structurally complex settings,with implications for geotechnical applications.
基金Funded by the Chongqing Natural Science Foundation Project(No.cstc202ljcyj-msxmX0725)。
文摘We employed machine learning approaches and visualization interpretation methods to explore the influencing factors of the compressive strength of sea sand concrete to attain a better understanding of the inherent laws of concrete mix design.Four models,including random forest,Cat Boost,XGBoost,and deep neural network,were trained.The experimental results demonstrate that the XGBoost model performs the best in predicting the strength of sea sand concrete.Its R^(2)value reached 0.9999,and evaluation indexes such as MAPE,RMSE,MAE,and MSE are superior to those of other models.The principal component analysis(PCA)was conducted to visually analyze the structure and distribution of the original feature data,and Pearson correlation coefficient analysis and Shapley additive explanation(SHAP)were utilized to explore the impact of input characteristics on the strength of sea sand concrete.SHAP analysis is more conducive to revealing the nonlinear effects of various characteristics on the model prediction results,especially that particle size of stone has significant impacts on the strength of sea sand concrete.In addition,experimental verification was carried out to confirm the accuracy of the optimized training model.These findings offer some insights for the future design and application of sea sand in high-performance marine and coastal infrastructure.
基金supported by the National Key R&D Program of China[Grant No.2023YFF0713600]the National Natural Science Foundation of China[Grant No.62275062]+3 种基金Project of Shandong Innovation and Startup Community of High-end Medical Apparatus and Instruments[Grant No.2023-SGTTXM-002 and 2024-SGTTXM-005]the Shandong Province Technology Innovation Guidance Plan(Central Leading Local Science and Technology Development Fund)[Grant No.YDZX2023115]the Taishan Scholar Special Funding Project of Shandong Provincethe Shandong Laboratory of Advanced Biomaterials and Medical Devices in Weihai[Grant No.ZL202402].
文摘Photoacoustic-computed tomography is a novel imaging technique that combines high absorption contrast and deep tissue penetration capability,enabling comprehensive three-dimensional imaging of biological targets.However,the increasing demand for higher resolution and real-time imaging results in significant data volume,limiting data storage,transmission and processing efficiency of system.Therefore,there is an urgent need for an effective method to compress the raw data without compromising image quality.This paper presents a photoacoustic-computed tomography 3D data compression method and system based on Wavelet-Transformer.This method is based on the cooperative compression framework that integrates wavelet hard coding with deep learning-based soft decoding.It combines the multiscale analysis capability of wavelet transforms with the global feature modeling advantage of Transformers,achieving high-quality data compression and reconstruction.Experimental results using k-wave simulation suggest that the proposed compression system has advantages under extreme compression conditions,achieving a raw data compression ratio of up to 1:40.Furthermore,three-dimensional data compression experiment using in vivo mouse demonstrated that the maximum peak signal-to-noise ratio(PSNR)and structural similarity index(SSIM)values of reconstructed images reached 38.60 and 0.9583,effectively overcoming detail loss and artifacts introduced by raw data compression.All the results suggest that the proposed system can significantly reduce storage requirements and hardware cost,enhancing computational efficiency and image quality.These advantages support the development of photoacoustic-computed tomography toward higher efficiency,real-time performance and intelligent functionality.
基金supported by the National Natural Science Foundation of China(U2341288 and 12302492)。
文摘An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic responses of single ammonium perchlorate(AP)/octogen(HMX)particles embedded in a hydroxyl-terminated polybutadiene(HTPB)binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar(SHPB)system.The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured.During compression,transverse cracks developed within the AP particles,and their propagation led to particle fracturing,resulting in ductile fracturing.Unlike AP,HMX generated numerous short cracks within the internal and edge regions simultaneously,leading to fragmentation and brittle fracturing.Moreover,particle damage reduced the modulus of the sample,shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation.A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles.The simulation results agreed with the experimental observations.These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface,which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.
基金financial support provided by the National Natural Science Foundation of China(Grant No.12302472)the Science and Technology Support Program of Jiangsu Province(Grant No.BK20230874)+2 种基金the Aeronautical Science Fund(ASF)(Grant No.2023Z057052005)the Research Fund of State Key Laboratory of Mechanics and Control for Aerospace Structures(Nanjing University of Aeronautics and Astronautics)(Grant No.MCAS-I-0124G02)the funding received from Jiangsu Hanvo Safety Product Co.,Ltd。
文摘High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their ballistic limits.In this paper,a fiber-scale experimental method for characterizing ultrahigh strain-rate transverse compression behavior was proposed.To begin with,in order to measure the extremely low stress and strain in small specimens,the conventional Hopkinson bar was reduced to the hundred-micron scale,thereby achieving wave impedance matching with single fibers.In addition,tangential and normal laser Doppler velocimetry(LDV)methods were employed to realize non-contact,high-precision,and high-speed axial velocity measurements of micron-scale incident and transmission bars,respectively.Meanwhile,a microscopic observation system was used to facilitate the installation of miniature fiber samples.The experimental setup and procedures were introduced,and the system accuracy was verified through sample-free loading tests based on one-dimensional stress wave propagation theory.Dynamic compression experiments on Graphene-UHMWPE fibers were carried out,followed by post-compression microstructural characterization via scanning electron microscopy(SEM).Results demonstrated that successful mechanical characterization was achieved at strain rates exceeding 105,an order of magnitude higher than the previously reported maximum rates.Furthermore,during the loading process,the fibers underwent uniform compression deformation while exhibiting pronounced strain-rate effects.This method offers a novel approach for dynamic mechanical characterization of microscale single fibers,enabling the development of comprehensive strain-ratedependent material models to guide the design of advanced composites and high-performance fibers.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11505003 and 52325103)the Anhui Provincial Natural Science Foundation(Grant No.2108085MA25)。
文摘High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation.Among them,tungsten-based alloys demonstrate exceptional potential owing to their superior irradiation resistance.Recent experimental studies have demonstrated that W-Ta-Cr-V alloys exhibit excellent irradiation resistance under helium(He)ion irradiation.However,the underlying mechanisms,especially the migration behavior of He atoms,remain unclear.In this work,the influences of uniaxial tensile and compressive strain on He migration in W-Ta-Cr-V complex alloys have been systematically studied through first-principles calculations.Our results demonstrate that He atoms preferentially occupy the tetrahedral interstitial sites,with interstitial formation energies significantly reduced compared to pure W.The introduction of Ta,Cr,and V alloying elements markedly increases the He migration barriers,effectively suppressing He diffusion.Compressive strain increases the migration barriers,inhibiting He bubbles nucleation and growth,while tensile strain decreases the barriers,facilitating bubble formation.Compared to pure W,the W-Ta-Cr-V alloys exhibit both lower He interstitial formation energies and higher migration barriers,with further enhancement under compressive strain.Specifically,compressive strain of 6%increases the He migration barrier of the W-Ta-Cr-V alloy by 0.166 e V,which further widens the difference relative to pure W.These findings provide a theoretical explanation for the superior irradiation resistance of tungsten-based alloys observed experimentally and promote the understanding of irradiation damage in these alloys under strain.
