Hard tissue repair materials that balance high strength with low modulus are highly promising,representing a transformative focus in applied biomaterials research.In this study,Ti-Nb alloys with high performance are p...Hard tissue repair materials that balance high strength with low modulus are highly promising,representing a transformative focus in applied biomaterials research.In this study,Ti-Nb alloys with high performance are prepared by a low-cost process for orthopedic applications.Phase composition,modulus,compressive strength and recovery properties are effectively manipulated by tailoring trace amounts of interstitial oxygen.With increasing oxygen concentration in sintered Ti-Nb alloys,theβ(body centered cubic)phase was stabilized due to the lattice distortion.The elastic modulus declined from 91 to 24 GPa.The compressive strength slightly decreased from 1595 to 1404 MPa and yield strength increased from 760 to 904 MPa.Additionally,the recovery properties were enhanced by the interstitial oxygen as a shape memory alloy.The utilization of trace oxygen serves to modulate the thermoelastic martensitic transformation in Ti-Nb alloys,thereby obtaining appropriate mechanical properties.A notable reduction in modulus is achieved while maintaining high strength,which facilitates the development of orthopedic implants capable of withstanding more complex forces.展开更多
To investigate the influence of coarse aggregate parent rock properties on the elastic modulus of concrete,the mineralogical properties and stress-strain curves of granite and dolomite parent rocks,as well as the stre...To investigate the influence of coarse aggregate parent rock properties on the elastic modulus of concrete,the mineralogical properties and stress-strain curves of granite and dolomite parent rocks,as well as the strength and elastic modulus of mortar and concrete prepared with mechanism aggregates of the corresponding lithology,and the stress-strain curves of concrete were investigated.In this paper,a coarse aggregate and mortar matrix bonding assumption is proposed,and a prediction model for the elastic modulus of mortar is established by considering the lithology of the mechanism sand and the slurry components.An equivalent coarse aggregate elastic modulus model was established by considering factors such as coarse aggregate particle size,volume fraction,and mortar thickness between coarse aggregates.Based on the elastic modulus of the equivalent coarse aggregate and the remaining mortar,a prediction model for the elastic modulus of the two and three components of concrete in series and then in parallel was established,and the predicted values differed from the measured values within 10%.It is proposed that the coarse aggregate elastic modulus in highstrength concrete is the most critical factor affecting the elastic modulus of concrete,and as the coarse aggregate elastic modulus increases by 27.7%,the concrete elastic modulus increases by 19.5%.展开更多
This study proposes to use the unconfined compressive strength(UCS)and the bender element(BE)tests for determining the strength and the initial small-strain shear modulus of Bangkok soft marine clay improved by cement...This study proposes to use the unconfined compressive strength(UCS)and the bender element(BE)tests for determining the strength and the initial small-strain shear modulus of Bangkok soft marine clay improved by cement and polyester fibers.This study varies the content of admixed cement(1%–20%)and polyester fibers(0–20%),including the curing time(3–28 d)for preparing 360 samples.Moreover,this study uses the Michaelis-Menten kinetics concept to model cement hydration saturation.From the study,it is concluded as follows.The modelled results reveals that at least 10%cement and 1%polyester fiber are recommended to attain the 28-d UCS standards(294 kPa)for highway subgrade materials in Thailand.This also fulfils sustainable construction due to reducing normal-use cement from 20%to 10%.Unfortunately,the addition of polyester fibers into the Bangkok clay with at least 5%cement reduces shear modulus by 1.12–1.32 times.The Abram's relationship between shear modulus and the mixing-water-to-cement ratio is found time-dependent.From the composite theory,the BE detects the polyester fiber zone as a defect in the Bangkok clay(matrix)with 5%–20%cement.So,the 28-d shear modulus in the polyester fiber zone is negative(up to0.034 MPa for 20%fiber),similar to softening phenomenon in concrete cracking(negative stiffness).For the 28-d shear modulus of fiber zone,the optimum cement content is around 2%for the positive influences of polyester fibers.Experimentally,the timedependent normalized UCS for 10%and 20%cement is compatible with other studies,and its development rate increases with the cement content as 0.3017,0.3172 and 0.3204 for 5%,10%and 20%cement,respectively.The 28-d relationship between shear modulus and UCS shows that low-cement soft clay requires high polyester fiber content(5%–20%)to activate UCS improvement.However,the soft clay with enough cement(20%)causes the uniformly distributed UCS improvement.展开更多
Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes...Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes with SiO_(2)and Al_(2)O_(3)ratios were investigated using various techniques.It is found that when SiO_(2)is replaced by Al_(2)O_(3),the Q^(4) to Q^(3) transition of silicon-oxygen network decreases while the aluminum-oxygen network increases,which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases.The glass transition temperature(T_(g))increases continuously,while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases.Meanwhile,the elastic modulus values increase from 93 to 102 GPa.This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy,and elements with higher packing factors and dissociation energies supplant those with lower values,resulting in increased rigidity within the glass.展开更多
Conductive hydrogel-based stretchable electronics have been extensively investigated,among which strain sensors are the most prominently studied.While the mechanical properties significantly affect the performance of ...Conductive hydrogel-based stretchable electronics have been extensively investigated,among which strain sensors are the most prominently studied.While the mechanical properties significantly affect the performance of these devices,the systematic correlation between specific mechanical parameters and sensing performance remains rarely explored.This work compares the influences of Young’s modulus and mechanical hysteresis on the sensing performance between highly entangled PAM-Li and double-network PAM-Li-Agar-3 strain sensors.Owing to the brittle agar network,which imparts a higher Young’s modulus and pronounced mechanical hysteresis to the double-network PAMLi-Agar-3 hydrogel,the corresponding sensor requires a greater driving force for deformation and yields signals with poor reproducibility.In comparison,the PAM-Li hydrogel,characterized by highly entangled polymer chains,exhibits a lower Young’s modulus and negligible mechanical hysteresis.Consequently,signals from the PAM-Li strain sensor demonstrate enhanced sensitivity and stability.Therefore,this work demonstrates that a low Young’s modulus and minimal mechanical hysteresis are critical factors for achieving superior sensing performance in strain sensors,as systematically validated through comparative analyses across diverse application scenarios.展开更多
In the present study Ti-Nb binary alloy system was chosen because it has excellent biocompatibility as well as reasonable mechanical properties,aiming at understanding oxygen content on microstructural formation, elas...In the present study Ti-Nb binary alloy system was chosen because it has excellent biocompatibility as well as reasonable mechanical properties,aiming at understanding oxygen content on microstructural formation, elastic modulus and tensile properties in Ti-Nb alloy system.Small alloy buttons of 50 mm in diameter were prepared by arc melting on a water-cooled copper hearth under an argon gas atmosphere with a non-consumable tungsten electrode.The button ingots were then heat treated in a vacuum atmosphere at 1273 K for 0.5 h followed by water quenching in a specially designed heat treatment furnace.Microstructure,elastic modulus and tensile properties were investigated in order to understand the effect of oxygen content in quenched Ti- Nb alloy system.The orthorhombic structuredα″martensite was changed to bcc structuredβ-phase with increasing Nb content.Interestingly,it was found that oxygen makesβ-phase stable in quenched Ti-Nb alloy system.Elastic modulus values were sensitive to phase stability of constituent phases.Yield strength increased with increasing oxygen content.Details will be explained by phase formation and stability behavior.展开更多
In the present paper,the hardness and Young's modulus of film-substrate systems are determined by means of nanoindentation experiments and modified models.Aluminum film and two kinds of substrates,i.e.glass and si...In the present paper,the hardness and Young's modulus of film-substrate systems are determined by means of nanoindentation experiments and modified models.Aluminum film and two kinds of substrates,i.e.glass and silicon,are studied.Nanoindentation XP Ⅱ and continuous stiffness mode are used during the experiments.In order to avoid the influence of the Oliver and Pharr method used in the experiments,the experiment data are analyzed with the constant Young's modulus assumption and the equal hardness assumption.The volume fraction model(CZ model)proposed by Fabes et al.(1992)is used and modified to analyze the measured hardness.The method proposed by Doerner and Nix(DN formula)(1986)is modified to analyze the measured Young's modulus.Two kinds of modified empirical formula are used to predict the present experiment results and those in the literature,which include the results of two kinds of systems,i.e.,a soft film on a hard substrate and a hard film on a soft substrate.In the modified CZ model,the indentation influence angle,(?), is considered as a relevant physical parameter,which embodies the effects of the indenter tip radius, pile-up or sink-in phenomena and deformation of film and substrate.展开更多
A simple uniaxial oedometric system is developed to test the elastic modulus of granular materials. The stress- strain relationship is first measured under conditions of uniaxial compression with additional lateral st...A simple uniaxial oedometric system is developed to test the elastic modulus of granular materials. The stress- strain relationship is first measured under conditions of uniaxial compression with additional lateral stress and strain, then the elastic modulus of the material is determined by the linear fitting method. It is found that the modulus is positively correlated to the grain size and negatively correlated to the container size. Arching and dragging are revealed to be the mechanism of such correlations by using the digital image correlation method and the pressure film technology based on the statistical method.展开更多
It has been experimentally shown that epoxide-terminated hyperbranched polyether sulphone （EHBPES） can significantly improve the mechanical properties of traditional diglycidyl ether of bisphenol A/triethylenetetram...It has been experimentally shown that epoxide-terminated hyperbranched polyether sulphone （EHBPES） can significantly improve the mechanical properties of traditional diglycidyl ether of bisphenol A/triethylenetetramine （DGEBA/TETA） systems, but the origin of the improvement is still unclear. In this work, we used molecular dynamics （MD） simulations to gain a thorough understanding of the origin of modulus improvement for EHBPES/DGEBA/TETA systems. It is found that the modulus of EHBPES/DGEBA/TETA systems increases with the increase of EHBPES loading. In addition, the crosslinking density, cohesive energy density （CED）, and free volume can be used to understand the modulus for EHBPES/DGEBA/TETA systems. It is shown that the highest modulus is achieved at 7 wt% EHBPES loading due to the highest crosslinking density and CED. When EHBPES loading is below 7 wt%, the higher CED and crosslinking density are responsible for the higher modulus. At higher loadings （〉 7 wt%）, the decreased modulus is closely related to the decreased crosslinking density and increased fractional free volume. It is expected that our results could be of great implications for designing high-performance epoxy materials.展开更多
This paper investigates adaptive blind source separation and equalization for Multiple Input Multiple Output (MIMO) systems. To effectively recover input signals, remove Inter-Symbol Interference (ISI) and suppress In...This paper investigates adaptive blind source separation and equalization for Multiple Input Multiple Output (MIMO) systems. To effectively recover input signals, remove Inter-Symbol Interference (ISI) and suppress Inter-User Interference (IUI), the array input is first transformed into the signal subspace, then with the derived orthogonality between weight vectors of different input signals, a new orthogonal Constant Modulus Algorithm (CMA) is proposed. Computer simulation results illustrate the promising performance of the proposed method. Without channel identification, the proposed method can recover all the system inputs simultaneously and can be adaptive to channel changes without prior knowledge about signals.展开更多
Based on the hypothesis of elastic two-layered foundation system under in-finite slab with known values of thicknesses of various layers and slab modulus,a programADMODE for evaluating foundation modulus is worked out...Based on the hypothesis of elastic two-layered foundation system under in-finite slab with known values of thicknesses of various layers and slab modulus,a programADMODE for evaluating foundation modulus is worked out by putting the inverse com-putation idea for moduli of various layers of foundation into an optimization problem.The validities of the theory and program have been checked and verified by taboratorytest.Besides,the foundation modulus have also been computed with this program by usingthe data obtained from Tai-Zhou experimental road.Through regression analyses,theempirical formulas for computing the increasing multiples of the moduli of subgrade andbase course are presented.展开更多
Elastic modulus(E)interpretation is debatable with limited literature detailing the impact of systemcompliance.To address this impact,a comprehensive testing schedule using an aluminium 6061(Al)sample is carried out o...Elastic modulus(E)interpretation is debatable with limited literature detailing the impact of systemcompliance.To address this impact,a comprehensive testing schedule using an aluminium 6061(Al)sample is carried out on several systems under various test setups.Al is chosen as it is extruded and adheres to well defined shape tolerances and elastic properties.A robust method,using the Savitzky-Golay filter,is introduced to identify significant slope changes in the stressestrain curve.Since the load in the test system is well defined,the recorded deformation is corrected to the expected value of Al resulting in a system-compliance factor.The results across the testing systems and test setups showed significant variance,with the recorded E always lower than the anticipated EAl.The number of components within the system over which the deformation is measured had the most significant impact,lowering the expected E by up to 50%.Additionally,the system-compliance factor is inconsistent across different systems and setups.Thus,it is evidently proved that each setup must be separately evaluated for its system-compliance and that no single value exists across systems and setups.The findings are then projected onto a series of uniaxial compressive strength(UCS)tests carried out on Stanstead granite(SS GR)samples.The corrected Et50 and Eavg values for system-compliance of the samples are within1%for each system as opposed to being50%pre-correction.The findings conclude that it is deemed necessary and of utmost importance that the deformation be corrected to accommodate the systemcompliance to obtain reliable results.展开更多
A new mulfitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus alg...A new mulfitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus algorithm （D-DDLSCMA）. In the new algorithm, the pre-despreading is first applied for multitarget arrays to remove some multiple access signals, then the despreaded signal is processed by the algorithm which united the constant modulus algorithm and decision directed method. Simulation results illustrate the good performance for the proposed algorithm.展开更多
Blind Adaptive Step-size Constant Modulus Algorithm (AS-CMA) for multiuser detection in DS-CDMA systems is presented. It combines the CMA and the concept of variable step-size, uses a second LMS algorithm for the step...Blind Adaptive Step-size Constant Modulus Algorithm (AS-CMA) for multiuser detection in DS-CDMA systems is presented. It combines the CMA and the concept of variable step-size, uses a second LMS algorithm for the step size. It adjusts the step-size according to the minimum output-energy principle within a specified range, thus overcomes the problems of bad effect of fixed step-size LMS algorithm. Compared with Adaptive Step-size LMS (AS-LMS) algoritilrn, through simulations, this algorithm can adapt the changes of the environment, suppress multiple access interference in the dynamic environment and the stability of Signal to Interference Ratio (SIR) is superior to that of AS-LMS.展开更多
Young's modulus and Poisson's ratio are crucial parameters for reservoir characterization and rock brittleness evaluation.Conventional methods often rely on indirect computation or approximations of the Zoeppr...Young's modulus and Poisson's ratio are crucial parameters for reservoir characterization and rock brittleness evaluation.Conventional methods often rely on indirect computation or approximations of the Zoeppritz equations to estimate Young's modulus,which can introduce cumulative errors and reduce the accuracy of inversion results.To address these issues,this paper introduces the analytical solution of the Zoeppritz equation into the inversion process.The equation is re-derived and expressed in terms of Young's modulus,Poisson's ratio,and density.Within the Bayesian framework,we construct an objective function for the joint inversion of PP and PS waves.Traditional gradient-based algorithms often suffer from low precision and the computational complexity.In this study,we address limitations of conventional approaches related to low precision and complicated code by using Circle chaotic mapping,Levy flights,and Gaussian mutation to optimize the quantum particle swarm optimization(QPSO),named improved quantum particle swarm optimization(IQPSO).The IQPSO demonstrates superior global optimization capabilities.We test the proposed inversion method with both synthetic and field data.The test results demonstrate the proposed method's feasibility and effectiveness,indicating an improvement in inversion accuracy over traditional methods.展开更多
Optogenetic has been widely applied in various pathogenesis investigations of neuropathic diseases since its accurate and targeted regulation of neuronal activity.However,due to the mismatch between the soft tissues a...Optogenetic has been widely applied in various pathogenesis investigations of neuropathic diseases since its accurate and targeted regulation of neuronal activity.However,due to the mismatch between the soft tissues and the optical waveguide,the long-term neural regulation within soft tissue(such as brain and spinal cord)by implantable optical fibers is a large challenge.Herein,we designed a modulus selfadaptive hydrogel optical fiber(MSHOF)with tunable mechanical properties(Young’modulus was tunable in the range of 0.32-10.56MPa)and low light attenuation(0.12-0.21 dB/cm,472nm laser light),which adapts to light transmission under soft tissues.These advantages of MSHOF can ensure the effectiveness of optogenetic stimulation meanwhile safeguarding the safety of the brain/materials interaction interface.In addition,this work provides more design possibilities of MSHOF for photogenetic stimuli and has significant application prospects in photomedical therapy.展开更多
Porous designs effectively reduce stress shielding in metallic orthopedic implants.However,current porous structures often fail to adequately meet the needs of patients with osteoporosis and low-modulus body regions.T...Porous designs effectively reduce stress shielding in metallic orthopedic implants.However,current porous structures often fail to adequately meet the needs of patients with osteoporosis and low-modulus body regions.This study proposes a sinusoidal-based lattice structure for an ultralow and widely tunable modulus design,aiming to match diverse bone tissue requirements and enhance biomechanical compatibility.Parametric modeling and finite element analysis were used to evaluate the performance of this structure.Results show that,within the design range suitable for bone growth,the elastic modulus of this lattice structure is tunable over a wide range,from 0.09 to 32.67 GPa,outperforming existing porous structures.The lowest value closely matched the minimum mechanical properties of human cancellous bone among porous structures.Moreover,the structure exhibited distinct anisotropic characteristics,allowing for directional design based on mechanical requirements.The structure’s permeability ranged from 1.19×10^(-8) m^(2) to 2.3×10^(-7) m^(2),making it highly compatible with human cancellous bone and meeting the requirements of orthopedic implants.Samples with porosities ranging from 46% to 87% were successfully fabricated using powder bed fusion additive manufacturing,validating the simulation predictions.This tunable low-modulus lattice structure provides a novel approach for developing personalized orthopedic implants,particularly for patients with specialized needs such as osteoporosis,and can potentially enhance biomechanical compatibility and long-term stability.展开更多
Discrete fracture network(DFN)commonly existing in natural rock masses plays an important role in geological complexity which can influence rock fracturing behaviour during fluid injection.This paper simulated the hyd...Discrete fracture network(DFN)commonly existing in natural rock masses plays an important role in geological complexity which can influence rock fracturing behaviour during fluid injection.This paper simulated the hydraulic fracturing process in lab-scale coal samples with DFNs and the induced seismic activities by the discrete element method(DEM).The effects of DFNs on hydraulic fracturing,induced seismicity and elastic property changes have been concluded.Denser DFNs can comprehensively decrease the peak injection pressure and injection duration.The proportion of strong seismic events increases first and then decreases with increasing DFN density.In addition,the relative modulus of the rock mass is derived innovatively from breakdown pressure,breakdown fracture length and the related initiation time.Increasing DFN densities among large(35–60 degrees)and small(0–30 degrees)fracture dip angles show opposite evolution trends in relative modulus.The transitional point(dip angle)for the opposite trends is also proportionally affected by the friction angle of the rock mass.The modelling results have much practical meaning to infer the density and geometry of pre-existing fractures and the elastic property of rock mass in the field,simply based on the hydraulic fracturing and induced seismicity monitoring data.展开更多
Lithium-sulfur(Li-S)batteries exhibit exceptional high theoretical energy density.However,their practical application is hindered by premature termination of discharge,which severely limits the discharge capacity and ...Lithium-sulfur(Li-S)batteries exhibit exceptional high theoretical energy density.However,their practical application is hindered by premature termination of discharge,which severely limits the discharge capacity and achievable energy density even at low discharge rates.This contribution identifies blocked mass transfer as the primary limitation through relaxation analysis.Both X-ray computed tomography and finite element simulation manifest that the preferential solid deposition at the working cathode surface obstructs the mass transfer pathway and triggers premature discharge termination.The Thiele modulus of a thick cathode is utilized to elucidate the disparity between electrochemical reaction and mass transfer rates,underscoring internal diffusion limitations as the root cause.This understanding affords a theoretical framework for optimizing cathode structures.By reducing the Thiele modulus,an enhanced energy density of 436 Wh kg^(-1)is achieved in Li-S pouch cells.This work advances the understanding of multi-phase reactions in Li-S batteries and offers insights to electrochemical systems involving multi-phase conversions.展开更多
In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order hom...In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.展开更多
基金Project(52501069)supported by the National Natural Science Foundation of ChinaProject(GZC20233172)supported by the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)Project(21B0121)supported by Hunan Provincial Education Department,China。
文摘Hard tissue repair materials that balance high strength with low modulus are highly promising,representing a transformative focus in applied biomaterials research.In this study,Ti-Nb alloys with high performance are prepared by a low-cost process for orthopedic applications.Phase composition,modulus,compressive strength and recovery properties are effectively manipulated by tailoring trace amounts of interstitial oxygen.With increasing oxygen concentration in sintered Ti-Nb alloys,theβ(body centered cubic)phase was stabilized due to the lattice distortion.The elastic modulus declined from 91 to 24 GPa.The compressive strength slightly decreased from 1595 to 1404 MPa and yield strength increased from 760 to 904 MPa.Additionally,the recovery properties were enhanced by the interstitial oxygen as a shape memory alloy.The utilization of trace oxygen serves to modulate the thermoelastic martensitic transformation in Ti-Nb alloys,thereby obtaining appropriate mechanical properties.A notable reduction in modulus is achieved while maintaining high strength,which facilitates the development of orthopedic implants capable of withstanding more complex forces.
基金Funded by State Railway Administration Research Project(No.2023JS007)National Natural Science Foundation of China(No.52438002)+1 种基金Research and Development Programs for Science and Technology of China Railways Corporation(No.J2023G003)New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘To investigate the influence of coarse aggregate parent rock properties on the elastic modulus of concrete,the mineralogical properties and stress-strain curves of granite and dolomite parent rocks,as well as the strength and elastic modulus of mortar and concrete prepared with mechanism aggregates of the corresponding lithology,and the stress-strain curves of concrete were investigated.In this paper,a coarse aggregate and mortar matrix bonding assumption is proposed,and a prediction model for the elastic modulus of mortar is established by considering the lithology of the mechanism sand and the slurry components.An equivalent coarse aggregate elastic modulus model was established by considering factors such as coarse aggregate particle size,volume fraction,and mortar thickness between coarse aggregates.Based on the elastic modulus of the equivalent coarse aggregate and the remaining mortar,a prediction model for the elastic modulus of the two and three components of concrete in series and then in parallel was established,and the predicted values differed from the measured values within 10%.It is proposed that the coarse aggregate elastic modulus in highstrength concrete is the most critical factor affecting the elastic modulus of concrete,and as the coarse aggregate elastic modulus increases by 27.7%,the concrete elastic modulus increases by 19.5%.
基金allocated by National Science,Research and Innovation Fund(NSRF)King Mongkut's University of Technology North Bangkok(project no.KMUTNB-FF-67-B-44 and KMUTNB-FF-67-B-45)supported by the NSRF through the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(grant no.B40G660036).
文摘This study proposes to use the unconfined compressive strength(UCS)and the bender element(BE)tests for determining the strength and the initial small-strain shear modulus of Bangkok soft marine clay improved by cement and polyester fibers.This study varies the content of admixed cement(1%–20%)and polyester fibers(0–20%),including the curing time(3–28 d)for preparing 360 samples.Moreover,this study uses the Michaelis-Menten kinetics concept to model cement hydration saturation.From the study,it is concluded as follows.The modelled results reveals that at least 10%cement and 1%polyester fiber are recommended to attain the 28-d UCS standards(294 kPa)for highway subgrade materials in Thailand.This also fulfils sustainable construction due to reducing normal-use cement from 20%to 10%.Unfortunately,the addition of polyester fibers into the Bangkok clay with at least 5%cement reduces shear modulus by 1.12–1.32 times.The Abram's relationship between shear modulus and the mixing-water-to-cement ratio is found time-dependent.From the composite theory,the BE detects the polyester fiber zone as a defect in the Bangkok clay(matrix)with 5%–20%cement.So,the 28-d shear modulus in the polyester fiber zone is negative(up to0.034 MPa for 20%fiber),similar to softening phenomenon in concrete cracking(negative stiffness).For the 28-d shear modulus of fiber zone,the optimum cement content is around 2%for the positive influences of polyester fibers.Experimentally,the timedependent normalized UCS for 10%and 20%cement is compatible with other studies,and its development rate increases with the cement content as 0.3017,0.3172 and 0.3204 for 5%,10%and 20%cement,respectively.The 28-d relationship between shear modulus and UCS shows that low-cement soft clay requires high polyester fiber content(5%–20%)to activate UCS improvement.However,the soft clay with enough cement(20%)causes the uniformly distributed UCS improvement.
基金Supported by the National Key Research Program(No.2024-1129-954-112)National Natural Science Foundation of China(No.52372033)Guangxi Science and Technology Major Program(No.AA24263054)。
文摘Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes with SiO_(2)and Al_(2)O_(3)ratios were investigated using various techniques.It is found that when SiO_(2)is replaced by Al_(2)O_(3),the Q^(4) to Q^(3) transition of silicon-oxygen network decreases while the aluminum-oxygen network increases,which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases.The glass transition temperature(T_(g))increases continuously,while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases.Meanwhile,the elastic modulus values increase from 93 to 102 GPa.This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy,and elements with higher packing factors and dissociation energies supplant those with lower values,resulting in increased rigidity within the glass.
基金supported by the National Natural Science Foundation of China(52303145,52403083)the Natural Science Foundation of Sichuan Province(2025ZNSFSC1400)supported by the start-up funding at Chengdu University(T202207)。
文摘Conductive hydrogel-based stretchable electronics have been extensively investigated,among which strain sensors are the most prominently studied.While the mechanical properties significantly affect the performance of these devices,the systematic correlation between specific mechanical parameters and sensing performance remains rarely explored.This work compares the influences of Young’s modulus and mechanical hysteresis on the sensing performance between highly entangled PAM-Li and double-network PAM-Li-Agar-3 strain sensors.Owing to the brittle agar network,which imparts a higher Young’s modulus and pronounced mechanical hysteresis to the double-network PAMLi-Agar-3 hydrogel,the corresponding sensor requires a greater driving force for deformation and yields signals with poor reproducibility.In comparison,the PAM-Li hydrogel,characterized by highly entangled polymer chains,exhibits a lower Young’s modulus and negligible mechanical hysteresis.Consequently,signals from the PAM-Li strain sensor demonstrate enhanced sensitivity and stability.Therefore,this work demonstrates that a low Young’s modulus and minimal mechanical hysteresis are critical factors for achieving superior sensing performance in strain sensors,as systematically validated through comparative analyses across diverse application scenarios.
文摘In the present study Ti-Nb binary alloy system was chosen because it has excellent biocompatibility as well as reasonable mechanical properties,aiming at understanding oxygen content on microstructural formation, elastic modulus and tensile properties in Ti-Nb alloy system.Small alloy buttons of 50 mm in diameter were prepared by arc melting on a water-cooled copper hearth under an argon gas atmosphere with a non-consumable tungsten electrode.The button ingots were then heat treated in a vacuum atmosphere at 1273 K for 0.5 h followed by water quenching in a specially designed heat treatment furnace.Microstructure,elastic modulus and tensile properties were investigated in order to understand the effect of oxygen content in quenched Ti- Nb alloy system.The orthorhombic structuredα″martensite was changed to bcc structuredβ-phase with increasing Nb content.Interestingly,it was found that oxygen makesβ-phase stable in quenched Ti-Nb alloy system.Elastic modulus values were sensitive to phase stability of constituent phases.Yield strength increased with increasing oxygen content.Details will be explained by phase formation and stability behavior.
基金The project supported by the National Natural Science Foundation of China (10202023,10272103),the Excellent Post-doctoral Research-starting Fund of CAS and the Key Project from CAS (No.KJCX2-SW-L2)
文摘In the present paper,the hardness and Young's modulus of film-substrate systems are determined by means of nanoindentation experiments and modified models.Aluminum film and two kinds of substrates,i.e.glass and silicon,are studied.Nanoindentation XP Ⅱ and continuous stiffness mode are used during the experiments.In order to avoid the influence of the Oliver and Pharr method used in the experiments,the experiment data are analyzed with the constant Young's modulus assumption and the equal hardness assumption.The volume fraction model(CZ model)proposed by Fabes et al.(1992)is used and modified to analyze the measured hardness.The method proposed by Doerner and Nix(DN formula)(1986)is modified to analyze the measured Young's modulus.Two kinds of modified empirical formula are used to predict the present experiment results and those in the literature,which include the results of two kinds of systems,i.e.,a soft film on a hard substrate and a hard film on a soft substrate.In the modified CZ model,the indentation influence angle,(?), is considered as a relevant physical parameter,which embodies the effects of the indenter tip radius, pile-up or sink-in phenomena and deformation of film and substrate.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11372038 and 11402023
文摘A simple uniaxial oedometric system is developed to test the elastic modulus of granular materials. The stress- strain relationship is first measured under conditions of uniaxial compression with additional lateral stress and strain, then the elastic modulus of the material is determined by the linear fitting method. It is found that the modulus is positively correlated to the grain size and negatively correlated to the container size. Arching and dragging are revealed to be the mechanism of such correlations by using the digital image correlation method and the pressure film technology based on the statistical method.
基金financially supported by CHEMCLOUD-COMPUTINGthe National Natural Science Foundation of China (No.51173012)
文摘It has been experimentally shown that epoxide-terminated hyperbranched polyether sulphone （EHBPES） can significantly improve the mechanical properties of traditional diglycidyl ether of bisphenol A/triethylenetetramine （DGEBA/TETA） systems, but the origin of the improvement is still unclear. In this work, we used molecular dynamics （MD） simulations to gain a thorough understanding of the origin of modulus improvement for EHBPES/DGEBA/TETA systems. It is found that the modulus of EHBPES/DGEBA/TETA systems increases with the increase of EHBPES loading. In addition, the crosslinking density, cohesive energy density （CED）, and free volume can be used to understand the modulus for EHBPES/DGEBA/TETA systems. It is shown that the highest modulus is achieved at 7 wt% EHBPES loading due to the highest crosslinking density and CED. When EHBPES loading is below 7 wt%, the higher CED and crosslinking density are responsible for the higher modulus. At higher loadings （〉 7 wt%）, the decreased modulus is closely related to the decreased crosslinking density and increased fractional free volume. It is expected that our results could be of great implications for designing high-performance epoxy materials.
文摘This paper investigates adaptive blind source separation and equalization for Multiple Input Multiple Output (MIMO) systems. To effectively recover input signals, remove Inter-Symbol Interference (ISI) and suppress Inter-User Interference (IUI), the array input is first transformed into the signal subspace, then with the derived orthogonality between weight vectors of different input signals, a new orthogonal Constant Modulus Algorithm (CMA) is proposed. Computer simulation results illustrate the promising performance of the proposed method. Without channel identification, the proposed method can recover all the system inputs simultaneously and can be adaptive to channel changes without prior knowledge about signals.
文摘Based on the hypothesis of elastic two-layered foundation system under in-finite slab with known values of thicknesses of various layers and slab modulus,a programADMODE for evaluating foundation modulus is worked out by putting the inverse com-putation idea for moduli of various layers of foundation into an optimization problem.The validities of the theory and program have been checked and verified by taboratorytest.Besides,the foundation modulus have also been computed with this program by usingthe data obtained from Tai-Zhou experimental road.Through regression analyses,theempirical formulas for computing the increasing multiples of the moduli of subgrade andbase course are presented.
基金This work has been supported through the Natural Sciences and Engineering Research Council of Canada(NSERC)PGS D3-518886,NSERC Discovery Grants 341275
文摘Elastic modulus(E)interpretation is debatable with limited literature detailing the impact of systemcompliance.To address this impact,a comprehensive testing schedule using an aluminium 6061(Al)sample is carried out on several systems under various test setups.Al is chosen as it is extruded and adheres to well defined shape tolerances and elastic properties.A robust method,using the Savitzky-Golay filter,is introduced to identify significant slope changes in the stressestrain curve.Since the load in the test system is well defined,the recorded deformation is corrected to the expected value of Al resulting in a system-compliance factor.The results across the testing systems and test setups showed significant variance,with the recorded E always lower than the anticipated EAl.The number of components within the system over which the deformation is measured had the most significant impact,lowering the expected E by up to 50%.Additionally,the system-compliance factor is inconsistent across different systems and setups.Thus,it is evidently proved that each setup must be separately evaluated for its system-compliance and that no single value exists across systems and setups.The findings are then projected onto a series of uniaxial compressive strength(UCS)tests carried out on Stanstead granite(SS GR)samples.The corrected Et50 and Eavg values for system-compliance of the samples are within1%for each system as opposed to being50%pre-correction.The findings conclude that it is deemed necessary and of utmost importance that the deformation be corrected to accommodate the systemcompliance to obtain reliable results.
文摘A new mulfitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus algorithm （D-DDLSCMA）. In the new algorithm, the pre-despreading is first applied for multitarget arrays to remove some multiple access signals, then the despreaded signal is processed by the algorithm which united the constant modulus algorithm and decision directed method. Simulation results illustrate the good performance for the proposed algorithm.
基金Supported by the National Natural Science Fundation of China(No.60172018)
文摘Blind Adaptive Step-size Constant Modulus Algorithm (AS-CMA) for multiuser detection in DS-CDMA systems is presented. It combines the CMA and the concept of variable step-size, uses a second LMS algorithm for the step size. It adjusts the step-size according to the minimum output-energy principle within a specified range, thus overcomes the problems of bad effect of fixed step-size LMS algorithm. Compared with Adaptive Step-size LMS (AS-LMS) algoritilrn, through simulations, this algorithm can adapt the changes of the environment, suppress multiple access interference in the dynamic environment and the stability of Signal to Interference Ratio (SIR) is superior to that of AS-LMS.
基金supported by Fundamental Research Funds for the Central Universities,CHD300102264715National Key Research and Development Program of China under Grant 2021YFA0716902Natural Science Basic Research Program of Shaanxi 2024JCYBMS-199。
文摘Young's modulus and Poisson's ratio are crucial parameters for reservoir characterization and rock brittleness evaluation.Conventional methods often rely on indirect computation or approximations of the Zoeppritz equations to estimate Young's modulus,which can introduce cumulative errors and reduce the accuracy of inversion results.To address these issues,this paper introduces the analytical solution of the Zoeppritz equation into the inversion process.The equation is re-derived and expressed in terms of Young's modulus,Poisson's ratio,and density.Within the Bayesian framework,we construct an objective function for the joint inversion of PP and PS waves.Traditional gradient-based algorithms often suffer from low precision and the computational complexity.In this study,we address limitations of conventional approaches related to low precision and complicated code by using Circle chaotic mapping,Levy flights,and Gaussian mutation to optimize the quantum particle swarm optimization(QPSO),named improved quantum particle swarm optimization(IQPSO).The IQPSO demonstrates superior global optimization capabilities.We test the proposed inversion method with both synthetic and field data.The test results demonstrate the proposed method's feasibility and effectiveness,indicating an improvement in inversion accuracy over traditional methods.
基金supported by the National Key Research and Development Program of China(Nos.2021YFA1201302 and 2021YFA1201300)the National Natural Science Foundation of China(Nos.52303033,52173029)+1 种基金Shanghai Sailing Program(No.23YF1400400)the Natural Science Foundation of Shanghai(No.21ZR1400500).
文摘Optogenetic has been widely applied in various pathogenesis investigations of neuropathic diseases since its accurate and targeted regulation of neuronal activity.However,due to the mismatch between the soft tissues and the optical waveguide,the long-term neural regulation within soft tissue(such as brain and spinal cord)by implantable optical fibers is a large challenge.Herein,we designed a modulus selfadaptive hydrogel optical fiber(MSHOF)with tunable mechanical properties(Young’modulus was tunable in the range of 0.32-10.56MPa)and low light attenuation(0.12-0.21 dB/cm,472nm laser light),which adapts to light transmission under soft tissues.These advantages of MSHOF can ensure the effectiveness of optogenetic stimulation meanwhile safeguarding the safety of the brain/materials interaction interface.In addition,this work provides more design possibilities of MSHOF for photogenetic stimuli and has significant application prospects in photomedical therapy.
基金supported by National Key R&D Program of China(Grant No.2022YFB4600500)Fundamental Research Funds for the Central Universities,and the Program for Innovation Team of Shaanxi Province(Grant No.2023-CX-TD-17).
文摘Porous designs effectively reduce stress shielding in metallic orthopedic implants.However,current porous structures often fail to adequately meet the needs of patients with osteoporosis and low-modulus body regions.This study proposes a sinusoidal-based lattice structure for an ultralow and widely tunable modulus design,aiming to match diverse bone tissue requirements and enhance biomechanical compatibility.Parametric modeling and finite element analysis were used to evaluate the performance of this structure.Results show that,within the design range suitable for bone growth,the elastic modulus of this lattice structure is tunable over a wide range,from 0.09 to 32.67 GPa,outperforming existing porous structures.The lowest value closely matched the minimum mechanical properties of human cancellous bone among porous structures.Moreover,the structure exhibited distinct anisotropic characteristics,allowing for directional design based on mechanical requirements.The structure’s permeability ranged from 1.19×10^(-8) m^(2) to 2.3×10^(-7) m^(2),making it highly compatible with human cancellous bone and meeting the requirements of orthopedic implants.Samples with porosities ranging from 46% to 87% were successfully fabricated using powder bed fusion additive manufacturing,validating the simulation predictions.This tunable low-modulus lattice structure provides a novel approach for developing personalized orthopedic implants,particularly for patients with specialized needs such as osteoporosis,and can potentially enhance biomechanical compatibility and long-term stability.
基金Australian Research Council Linkage Program(LP200301404)for sponsoring this researchthe financial support provided by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology,SKLGP2021K002)National Natural Science Foundation of China(52374101,32111530138).
文摘Discrete fracture network(DFN)commonly existing in natural rock masses plays an important role in geological complexity which can influence rock fracturing behaviour during fluid injection.This paper simulated the hydraulic fracturing process in lab-scale coal samples with DFNs and the induced seismic activities by the discrete element method(DEM).The effects of DFNs on hydraulic fracturing,induced seismicity and elastic property changes have been concluded.Denser DFNs can comprehensively decrease the peak injection pressure and injection duration.The proportion of strong seismic events increases first and then decreases with increasing DFN density.In addition,the relative modulus of the rock mass is derived innovatively from breakdown pressure,breakdown fracture length and the related initiation time.Increasing DFN densities among large(35–60 degrees)and small(0–30 degrees)fracture dip angles show opposite evolution trends in relative modulus.The transitional point(dip angle)for the opposite trends is also proportionally affected by the friction angle of the rock mass.The modelling results have much practical meaning to infer the density and geometry of pre-existing fractures and the elastic property of rock mass in the field,simply based on the hydraulic fracturing and induced seismicity monitoring data.
基金supported by the National Key Research and Development Program of China(2024YFE0209500)Relevant National Projects,the National Natural Science Foundation of China(22409116)+1 种基金the Seed Fund of Shanxi Research Institute for Clean Energy(SXKYJF015)the Shuimu Tsinghua Scholar Program of Tsinghua University。
文摘Lithium-sulfur(Li-S)batteries exhibit exceptional high theoretical energy density.However,their practical application is hindered by premature termination of discharge,which severely limits the discharge capacity and achievable energy density even at low discharge rates.This contribution identifies blocked mass transfer as the primary limitation through relaxation analysis.Both X-ray computed tomography and finite element simulation manifest that the preferential solid deposition at the working cathode surface obstructs the mass transfer pathway and triggers premature discharge termination.The Thiele modulus of a thick cathode is utilized to elucidate the disparity between electrochemical reaction and mass transfer rates,underscoring internal diffusion limitations as the root cause.This understanding affords a theoretical framework for optimizing cathode structures.By reducing the Thiele modulus,an enhanced energy density of 436 Wh kg^(-1)is achieved in Li-S pouch cells.This work advances the understanding of multi-phase reactions in Li-S batteries and offers insights to electrochemical systems involving multi-phase conversions.
基金support by the National Key R&D Program of China(Grant No.2023YFA1008901)the National Natural Science Foundation of China(Grant Nos.11988102,12172009)is gratefully acknowledged.
文摘In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.
