Elastic electronics are increasingly prevalent in information storage,smart sensing and health monitoring due to their softness,stretchability and portability.Wearable electronic devices should possess elasticity and ...Elastic electronics are increasingly prevalent in information storage,smart sensing and health monitoring due to their softness,stretchability and portability.Wearable electronic devices should possess elasticity and stretchability that align with biological tissues.Specifically,their materials should be capable of elastic strain up to 50–80%,while the devices themselves must maintain electric stability under strains that accommodate body movements[1].展开更多
Solids in nano-scales hold the promise to exhibit extreme strength and elasticity due to the absence of interior defects and the designability of micro-arrangements.A nano-scaled bulk sample can be produced by diamond...Solids in nano-scales hold the promise to exhibit extreme strength and elasticity due to the absence of interior defects and the designability of micro-arrangements.A nano-scaled bulk sample can be produced by diamond,ice,metallic twins,high entropy alloy(HEA),or cubic boron nitride(cBN).A loading stage capable of 4-DoF movements was designed and built to achieve multi-axial mechanical loading inside a transmission electronic microscope chamber with sub-nanometer loading precision.For single crystal diamond in the shape of nano-needles,we were able to achieve an extreme bending strength of 125 GPa at the tensile side,approaching the theoretical strength of diamond.For ice fibers of sub-micron radius,an extreme elastic strain of 10.9%was acquired,far exceeding the previous record of 0.3%for the elastic strain achievable by ice.For metallic twin specimens made by nano-welding,a shear strain as large as 364%was recorded parallel to the twin boundary.Cyclic shear loading aligned with the twin boundary would drive an up-and-down sweeping movement of the low-angle grain boundary,as composed by an array of dislocations.The sweep of the grain boundary effectively cleanses the lattice defects and creates a feasible scenario of unlimited cyclic endurance.For a HEA dog-bone specimen in nano-scale,an extreme elastic strain of about 10%was achieved.At this level of mechanical straining,stretch-induced melting for crystalline metals,as envisaged by Lindemann a century ago,was realized.For cBN crystals,a fracture path inclined to the stacking hexagon planes would result in a new failure mechanism of layered decohesion,triggered by the extremely large elastic strain(>7%)along the edge of the submicron-scaled specimen.These results indicate ample room for upgrading the mechanical behaviour of solids in nano-scales.展开更多
The increasing integration of small-scale structures in engineering,particularly in Micro-Electro-Mechanical Systems(MEMS),necessitates advanced modeling approaches to accurately capture their complex mechanical behav...The increasing integration of small-scale structures in engineering,particularly in Micro-Electro-Mechanical Systems(MEMS),necessitates advanced modeling approaches to accurately capture their complex mechanical behavior.Classical continuum theories are inadequate at micro-and nanoscales,particularly concerning size effects,singularities,and phenomena like strain softening or phase transitions.This limitation follows from their lack of intrinsic length scale parameters,crucial for representingmicrostructural features.Theoretical and experimental findings emphasize the critical role of these parameters on small scales.This review thoroughly examines various strain gradient elasticity(SGE)theories commonly employed in literature to capture these size-dependent effects on the elastic response.Given the complexity arising from numerous SGE frameworks available in the literature,including first-and second-order gradient theories,we conduct a comprehensive and comparative analysis of common SGE models.This analysis highlights their unique physical interpretations and compares their effectiveness in modeling the size-dependent behavior of low-dimensional structures.A brief discussion on estimating additional material constants,such as intrinsic length scales,is also included to improve the practical relevance of SGE.Following this theoretical treatment,the review covers analytical and numerical methods for solving the associated higher-order governing differential equations.Finally,we present a detailed overview of strain gradient applications in multiscale andmultiphysics response of solids.Interesting research on exploring the relevance of SGE for reduced-order modeling of complex macrostructures,a universal multiphysics coupling in low-dimensional structures without being restricted to limited material symmetries(as in the case of microstructures),is also presented here for interested readers.Finally,we briefly discuss alternative nonlocal elasticity approaches(integral and integro-differential)for incorporating size effects,and conclude with some potential areas for future research on strain gradients.This review aims to provide a clear understanding of strain gradient theories and their broad applicability beyond classical elasticity.展开更多
The identification of the traction acting on a portion of the surface of an anisotropic solid is very important in structural health monitoring and optimal design of structures. The traction can be determined using in...The identification of the traction acting on a portion of the surface of an anisotropic solid is very important in structural health monitoring and optimal design of structures. The traction can be determined using inverse methods in which displacement or strain measurements are taken at several points on the body. This paper presents an inverse method based on the method of fundamental solutions for the traction identification problem in two-dimensional anisotropic elasticity. The method of fundamental solutions is an efficient boundary-type meshless method widely used for analyzing various problems. Since the problem is linear, the sensitivity analysis is simply performed by solving the corresponding direct problem several times with different loads. The effects of important parameters such as the number of measurement data, the position of the measurement points, the amount of measurement error, and the type of measurement, i.e., displacement or strain, on the results are also investigated. The results obtained show that the presented inverse method is suitable for the problem of traction identification. It can be concluded from the results that the use of strain measurements in the inverse analysis leads to more accurate results than the use of displacement measurements. It is also found that measurement points closer to the boundary with unknown traction provide more reliable solutions. Additionally, it is found that increasing the number of measurement points increases the accuracy of the inverse solution. However, in cases with a large number of measurement points, further increasing the number of measurement data has little effect on the results.展开更多
The precise computation of nanoelectromechanical switches’(NEMS)multi-physical interactions requires advanced numerical models and is a crucial part of the development of micro-and nano-systems.This paper presents a ...The precise computation of nanoelectromechanical switches’(NEMS)multi-physical interactions requires advanced numerical models and is a crucial part of the development of micro-and nano-systems.This paper presents a novel compound numerical method to study the instability of a functionally graded(FG)beam-type NEMS,considering surface elasticity effects as stated by Gurtin-Murdoch theory in an Euler-Bernoulli beam.The presented method is based on a combination of the Method of Adjoints(MoA)together with the Bézier-based multistep technique.By utilizing the MoA,a boundary value problem(BVP)is turned into an initial value problem(IVP).The resulting IVP is then solved by employing a cost-efficient multi-step process.It is demonstrated that the mentioned method can arrive at a high level of accuracy.Furthermore,it is revealed that the stability of the presented methodology is far better than that of other common multi-step methods,such as Adams-Bashforth,particularly at higher step sizes.Finally,the effects of axially functionally graded(FG)properties on the pull-in phenomenon and the main design parameters of NEMS,including the detachment length,are inspected.It was shown that the main parameter of design is the modulus of elasticity of the material,as Silver(Ag),which had better mechanical properties,showed almost a 6%improvement compared to aluminum(Al).However,by applying the correct amount of material with sturdier surface parameters,such as Aluminum(Al),at certain points,the nanobeams’functionality can be improved even further by around 1.5%.展开更多
A Hamiltonian system is derived for the plane elasticity problem of two-dimensional dodecagonal quasicrystals by introducing the simple state function. By using symplectic elasticity approach, the analytic solutions o...A Hamiltonian system is derived for the plane elasticity problem of two-dimensional dodecagonal quasicrystals by introducing the simple state function. By using symplectic elasticity approach, the analytic solutions of the phonon and phason displacements are obtained further for the quasicrystal plates. In addition, the effectiveness of the approach is verified by comparison with the data of the finite integral transformation method.展开更多
Simultaneously achieving high elasticity,low modulus,and high strength in Ti alloy has been a long-standing challenge.In this study,cold rolling was conducted to modulate the martensitic transformation of the Ti-15Nb-...Simultaneously achieving high elasticity,low modulus,and high strength in Ti alloy has been a long-standing challenge.In this study,cold rolling was conducted to modulate the martensitic transformation of the Ti-15Nb-5Zr-4Sn-1Fe alloy to address this challenge.The 10%cold rolling process was primarily accommodated by a novel stress-induced sequential β-to-α″-to-α′martensitic transformation accompanied by the disappearance of ω phase,which was sufficient to induce adequate martensite and defects to suppress the initial rapid stress-induced martensitic transformation,without destroying the equiaxed shape of prio rβ grains.Consequently,the novel sequential phase transformation led to a substantial decrease in Young’s modulus by 50.5%while increasing the strength,resulting in an excellent combination of large near-linear elasticity of 2.34%,low modulus of 45 GPa,and high strength of 1093 MPa.The obtained large near-linear elasticity was mainly contributed by the concurrent low modulus and high strength obeying Hooke’s law.These findings provide valuable insights into the attainment of concurrent high elasticity and low modulus in Ti alloys by regulating the stress-induced sequential martensitic transformation.展开更多
Objective To observe the cervical elasticity of healthy adult nulliparous women at different age groups and different stages of menstrual cycle with E-Cervix imaging technology.Methods A total of 218 healthy adult nul...Objective To observe the cervical elasticity of healthy adult nulliparous women at different age groups and different stages of menstrual cycle with E-Cervix imaging technology.Methods A total of 218 healthy adult nulliparous women who underwent transvaginal ultrasound examination for routine physical examination were retrospectively enrolled,including 103 in follicular phase,78 in ovulation phase and 37 in luteal phase.Cervical canal length(CL)and E-Cervix elasticity parameters were compared among different age groups and different stages of menstrual cycle,including elasticity contrast index(ECI),hardness ratio(HR),cervical internal and external orifice strain values(IOS and EOS)and IOS/EOS ratio.Results No significant difference of CL nor cervical elasticity parameters was detected among healthy adult nulliparous women at different age groups(all P>0.05).There were significant differences of ECI,HR and IOS among different menstrual cycle stages(all P<0.05),among which women in follicular phase had higher ECI and IOS but lower HR than those in luteal phase(all P<0.05).Conclusion No significant difference of cervical elasticity existed among healthy adult nulliparous women at different age groups.Meanwhile,cervical elasticity of healthy adult nulliparous women changed during menstrual cycle,in follicular phase had higher ECI and IOS but lower HR than in luteal phase.展开更多
In performance analysis with tools such as data envelopment analysis,calculations of scale properties of the frontier points are studied using both qualitative and quantitative approaches.When the production process i...In performance analysis with tools such as data envelopment analysis,calculations of scale properties of the frontier points are studied using both qualitative and quantitative approaches.When the production process is a bit complicated,the calculation needs to be modified.Most existing studies are focused on a single-stage production process under the constant or variable returns to scale specification.However,some processes have two-stage structures,and,in such processes,the concepts of scale elasticity and returns to scale are inextricably related to the conditions of the stages of production.Thus,an evaluation of efficiency,scale elasticity,and returns to scale is sensitive to stages.In this study,we introduced a procedure to calculate technical efficiency and scale elasticity in a two-stage parallel-series production system.Then,our proposed technical efficiency and scale elasticity programs are applied to real data on 20 insurance companies in Iran.After applying our estimations to a real-world insurance industry,we found that,(i)overall,the total inputs of insurers in the life insurance sector should be reduced by 9%.Moreover,the inputs of nonlife insurers should be reduced by 50%.The final output in the investment sector must be increased by 48%.(ii)There are inefficiencies among all insurers in the investment sector,and to improve technical efficiency,the income from investments should be increased significantly.(iii)Finally,the efficiency and elasticity characterizations of insurers are directly subject to stages.展开更多
Correction:Financ Innov 10,43(2024)https://doi.org/10.1186/s40854-023-00578-z.Following publication of the original article(Amirteimoori et al.2024),the authors reported a typesetting error in the affiliation of autho...Correction:Financ Innov 10,43(2024)https://doi.org/10.1186/s40854-023-00578-z.Following publication of the original article(Amirteimoori et al.2024),the authors reported a typesetting error in the affiliation of author Tofigh Allahviranloo.展开更多
基金supported by generous grants from the Natural Science Foundation of Zhejiang Province(LR24E030003)Zhejiang Province Qianjiang Talent Program(ZJ-QJRC-2020-32).
文摘Elastic electronics are increasingly prevalent in information storage,smart sensing and health monitoring due to their softness,stretchability and portability.Wearable electronic devices should possess elasticity and stretchability that align with biological tissues.Specifically,their materials should be capable of elastic strain up to 50–80%,while the devices themselves must maintain electric stability under strains that accommodate body movements[1].
文摘Solids in nano-scales hold the promise to exhibit extreme strength and elasticity due to the absence of interior defects and the designability of micro-arrangements.A nano-scaled bulk sample can be produced by diamond,ice,metallic twins,high entropy alloy(HEA),or cubic boron nitride(cBN).A loading stage capable of 4-DoF movements was designed and built to achieve multi-axial mechanical loading inside a transmission electronic microscope chamber with sub-nanometer loading precision.For single crystal diamond in the shape of nano-needles,we were able to achieve an extreme bending strength of 125 GPa at the tensile side,approaching the theoretical strength of diamond.For ice fibers of sub-micron radius,an extreme elastic strain of 10.9%was acquired,far exceeding the previous record of 0.3%for the elastic strain achievable by ice.For metallic twin specimens made by nano-welding,a shear strain as large as 364%was recorded parallel to the twin boundary.Cyclic shear loading aligned with the twin boundary would drive an up-and-down sweeping movement of the low-angle grain boundary,as composed by an array of dislocations.The sweep of the grain boundary effectively cleanses the lattice defects and creates a feasible scenario of unlimited cyclic endurance.For a HEA dog-bone specimen in nano-scale,an extreme elastic strain of about 10%was achieved.At this level of mechanical straining,stretch-induced melting for crystalline metals,as envisaged by Lindemann a century ago,was realized.For cBN crystals,a fracture path inclined to the stacking hexagon planes would result in a new failure mechanism of layered decohesion,triggered by the extremely large elastic strain(>7%)along the edge of the submicron-scaled specimen.These results indicate ample room for upgrading the mechanical behaviour of solids in nano-scales.
基金support from the Anusandhan National Research Foundation(ANRF),erstwhile Science and Engineering Research Board(SERB),India,under the startup research grant program(SRG/2022/000566).
文摘The increasing integration of small-scale structures in engineering,particularly in Micro-Electro-Mechanical Systems(MEMS),necessitates advanced modeling approaches to accurately capture their complex mechanical behavior.Classical continuum theories are inadequate at micro-and nanoscales,particularly concerning size effects,singularities,and phenomena like strain softening or phase transitions.This limitation follows from their lack of intrinsic length scale parameters,crucial for representingmicrostructural features.Theoretical and experimental findings emphasize the critical role of these parameters on small scales.This review thoroughly examines various strain gradient elasticity(SGE)theories commonly employed in literature to capture these size-dependent effects on the elastic response.Given the complexity arising from numerous SGE frameworks available in the literature,including first-and second-order gradient theories,we conduct a comprehensive and comparative analysis of common SGE models.This analysis highlights their unique physical interpretations and compares their effectiveness in modeling the size-dependent behavior of low-dimensional structures.A brief discussion on estimating additional material constants,such as intrinsic length scales,is also included to improve the practical relevance of SGE.Following this theoretical treatment,the review covers analytical and numerical methods for solving the associated higher-order governing differential equations.Finally,we present a detailed overview of strain gradient applications in multiscale andmultiphysics response of solids.Interesting research on exploring the relevance of SGE for reduced-order modeling of complex macrostructures,a universal multiphysics coupling in low-dimensional structures without being restricted to limited material symmetries(as in the case of microstructures),is also presented here for interested readers.Finally,we briefly discuss alternative nonlocal elasticity approaches(integral and integro-differential)for incorporating size effects,and conclude with some potential areas for future research on strain gradients.This review aims to provide a clear understanding of strain gradient theories and their broad applicability beyond classical elasticity.
基金funded by Vice Chancellor of Research at Shiraz University(grant 3GFU2M1820).
文摘The identification of the traction acting on a portion of the surface of an anisotropic solid is very important in structural health monitoring and optimal design of structures. The traction can be determined using inverse methods in which displacement or strain measurements are taken at several points on the body. This paper presents an inverse method based on the method of fundamental solutions for the traction identification problem in two-dimensional anisotropic elasticity. The method of fundamental solutions is an efficient boundary-type meshless method widely used for analyzing various problems. Since the problem is linear, the sensitivity analysis is simply performed by solving the corresponding direct problem several times with different loads. The effects of important parameters such as the number of measurement data, the position of the measurement points, the amount of measurement error, and the type of measurement, i.e., displacement or strain, on the results are also investigated. The results obtained show that the presented inverse method is suitable for the problem of traction identification. It can be concluded from the results that the use of strain measurements in the inverse analysis leads to more accurate results than the use of displacement measurements. It is also found that measurement points closer to the boundary with unknown traction provide more reliable solutions. Additionally, it is found that increasing the number of measurement points increases the accuracy of the inverse solution. However, in cases with a large number of measurement points, further increasing the number of measurement data has little effect on the results.
文摘The precise computation of nanoelectromechanical switches’(NEMS)multi-physical interactions requires advanced numerical models and is a crucial part of the development of micro-and nano-systems.This paper presents a novel compound numerical method to study the instability of a functionally graded(FG)beam-type NEMS,considering surface elasticity effects as stated by Gurtin-Murdoch theory in an Euler-Bernoulli beam.The presented method is based on a combination of the Method of Adjoints(MoA)together with the Bézier-based multistep technique.By utilizing the MoA,a boundary value problem(BVP)is turned into an initial value problem(IVP).The resulting IVP is then solved by employing a cost-efficient multi-step process.It is demonstrated that the mentioned method can arrive at a high level of accuracy.Furthermore,it is revealed that the stability of the presented methodology is far better than that of other common multi-step methods,such as Adams-Bashforth,particularly at higher step sizes.Finally,the effects of axially functionally graded(FG)properties on the pull-in phenomenon and the main design parameters of NEMS,including the detachment length,are inspected.It was shown that the main parameter of design is the modulus of elasticity of the material,as Silver(Ag),which had better mechanical properties,showed almost a 6%improvement compared to aluminum(Al).However,by applying the correct amount of material with sturdier surface parameters,such as Aluminum(Al),at certain points,the nanobeams’functionality can be improved even further by around 1.5%.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12261064 and 11861048)the Natural Science Foundation of Inner Mongolia,China (Grant Nos.2021MS01004 and 2022QN01008)the High-level Talents Scientific Research Start-up Foundation of Inner Mongolia University (Grant No.10000-21311201/165)。
文摘A Hamiltonian system is derived for the plane elasticity problem of two-dimensional dodecagonal quasicrystals by introducing the simple state function. By using symplectic elasticity approach, the analytic solutions of the phonon and phason displacements are obtained further for the quasicrystal plates. In addition, the effectiveness of the approach is verified by comparison with the data of the finite integral transformation method.
基金financially supported by the National Natural Science Foundation of China(Nos.51671012 and 52001018)the Youth Talent Support Program of Beihang University.
文摘Simultaneously achieving high elasticity,low modulus,and high strength in Ti alloy has been a long-standing challenge.In this study,cold rolling was conducted to modulate the martensitic transformation of the Ti-15Nb-5Zr-4Sn-1Fe alloy to address this challenge.The 10%cold rolling process was primarily accommodated by a novel stress-induced sequential β-to-α″-to-α′martensitic transformation accompanied by the disappearance of ω phase,which was sufficient to induce adequate martensite and defects to suppress the initial rapid stress-induced martensitic transformation,without destroying the equiaxed shape of prio rβ grains.Consequently,the novel sequential phase transformation led to a substantial decrease in Young’s modulus by 50.5%while increasing the strength,resulting in an excellent combination of large near-linear elasticity of 2.34%,low modulus of 45 GPa,and high strength of 1093 MPa.The obtained large near-linear elasticity was mainly contributed by the concurrent low modulus and high strength obeying Hooke’s law.These findings provide valuable insights into the attainment of concurrent high elasticity and low modulus in Ti alloys by regulating the stress-induced sequential martensitic transformation.
文摘Objective To observe the cervical elasticity of healthy adult nulliparous women at different age groups and different stages of menstrual cycle with E-Cervix imaging technology.Methods A total of 218 healthy adult nulliparous women who underwent transvaginal ultrasound examination for routine physical examination were retrospectively enrolled,including 103 in follicular phase,78 in ovulation phase and 37 in luteal phase.Cervical canal length(CL)and E-Cervix elasticity parameters were compared among different age groups and different stages of menstrual cycle,including elasticity contrast index(ECI),hardness ratio(HR),cervical internal and external orifice strain values(IOS and EOS)and IOS/EOS ratio.Results No significant difference of CL nor cervical elasticity parameters was detected among healthy adult nulliparous women at different age groups(all P>0.05).There were significant differences of ECI,HR and IOS among different menstrual cycle stages(all P<0.05),among which women in follicular phase had higher ECI and IOS but lower HR than those in luteal phase(all P<0.05).Conclusion No significant difference of cervical elasticity existed among healthy adult nulliparous women at different age groups.Meanwhile,cervical elasticity of healthy adult nulliparous women changed during menstrual cycle,in follicular phase had higher ECI and IOS but lower HR than in luteal phase.
文摘In performance analysis with tools such as data envelopment analysis,calculations of scale properties of the frontier points are studied using both qualitative and quantitative approaches.When the production process is a bit complicated,the calculation needs to be modified.Most existing studies are focused on a single-stage production process under the constant or variable returns to scale specification.However,some processes have two-stage structures,and,in such processes,the concepts of scale elasticity and returns to scale are inextricably related to the conditions of the stages of production.Thus,an evaluation of efficiency,scale elasticity,and returns to scale is sensitive to stages.In this study,we introduced a procedure to calculate technical efficiency and scale elasticity in a two-stage parallel-series production system.Then,our proposed technical efficiency and scale elasticity programs are applied to real data on 20 insurance companies in Iran.After applying our estimations to a real-world insurance industry,we found that,(i)overall,the total inputs of insurers in the life insurance sector should be reduced by 9%.Moreover,the inputs of nonlife insurers should be reduced by 50%.The final output in the investment sector must be increased by 48%.(ii)There are inefficiencies among all insurers in the investment sector,and to improve technical efficiency,the income from investments should be increased significantly.(iii)Finally,the efficiency and elasticity characterizations of insurers are directly subject to stages.
文摘Correction:Financ Innov 10,43(2024)https://doi.org/10.1186/s40854-023-00578-z.Following publication of the original article(Amirteimoori et al.2024),the authors reported a typesetting error in the affiliation of author Tofigh Allahviranloo.
文摘随着算力网络中计算资源与虚拟化设备的广泛应用,在算力网络虚拟化中,针对云集群弹性伸缩策略基于阈值的响应式触发过程中存在的弹性滞后问题,提出一种基于Transformer的预测式云集群资源弹性伸缩方法(Predictive Cloud Cluster Resource Elastic Scaling Method Based on Transformer,Cloudformer).该方法利用序列分解模块将云集群数据分解为趋势项和季节项,趋势项采用双系数网络分别对输入空间预测的均值和方差进行归一化和反归一化,季节项采用融合傅里叶变换的频域自注意力模型进行预测,并在模型训练过程中使用指数移动平均模型动态调整训练损失的误差范围.实验结果表明,对比最先进的五种预测式弹性伸缩算法,本文所提出的方法在保持较低的模型训练和推理时间下,不同预测窗口单变量与多变量预测均方误差分别降低了10.07%和10.01%.
