As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be tre...As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be treated as a ma- terial of varying transverse isotropy. In this Part, the elastic stress-strain relations and the quadratic strength criterion are established in the form of having varying transverse isotropy, in the framework of micromechanics to take into account of the effect of the microstructures-dentin tubules. Simplified forms for isotropic and ho- mogeneous cases, as well as the corresponding plane stress form of the stress-strain relations are also given. These theoretical models are very well supported by the experiments shown later in the continued paper (Part Ⅱ).展开更多
A moisture-content based constitutive model was proposed based on the hyperbolic model as an attempt to move towards the implementation of unsaturated soil mechanics into routine geotechnical engineering practice. The...A moisture-content based constitutive model was proposed based on the hyperbolic model as an attempt to move towards the implementation of unsaturated soil mechanics into routine geotechnical engineering practice. The stress-strain behavior of in-situ soil at a depth of 5 m was investigated by conducting undrained triaxial compression tests using the remolded soil samples. The test results show that the stress-strain relationship of unsaturated cohesive soil is still hyperbolic. The values of parameters a and b given in the model decrease with increasing the confining pressure for soil samples with the same moisture content and increase with increasing the moisture content for soil samples under the same confining pressure. The relationships between parameters a, b and moisture content were studied for confining pressures of 100, 150, 200 and 250 kPa. The comparison between the measured and predicted stress-strain curves for an additional group of soil samples, having a moisture content of 25.4%, shows that the proposed moisture content-dependent hyperbolic model provides a good prediction of stress-strain behavior of unsaturated cohesive soil.展开更多
The research of the failure criterion and one-dimensional stress-strain relationship of deteriorated concrete were carried out. Based on the damage mechanics theory, the dsmage which reflects the alternation of intern...The research of the failure criterion and one-dimensional stress-strain relationship of deteriorated concrete were carried out. Based on the damage mechanics theory, the dsmage which reflects the alternation of internal state of material were introduced into the formula presented by Desayi and Krishman and the weighted twin-shear strength theory. As a nondestructive examination method in common use, the ultrasonic technique was adopted in the study, and the ultrasonic velocity was used to establish the damage variable. After that, the failure criterion and one-dimensional stress-strain relationship for deteriorated concrete were obtained. Eventually, tests were carried out to study the evolution laws on the damage. The results show that the more freezing and thawing cycles are, the more apparently the failure surface shrinks. Meanwhile, the comparison between theoretical data and experimental data verifies tile rationality of tile damage-based one-dimensional stress-strain relationship proposed.展开更多
Understanding the stress-strain relationship and permeability change for contact compression fracture at closing stage has been a hot issue for a long time.Previous investigations of this topic were mainly focused on ...Understanding the stress-strain relationship and permeability change for contact compression fracture at closing stage has been a hot issue for a long time.Previous investigations of this topic were mainly focused on experimental tests;however,theoretical approaches were rarely reported.Based on this,this paper focuses on the contact fracture at closing stage when rock is uniaxially loaded,and then a theoretical model is proposed.Based on the change of fracture elasticity modulus,it shows that as crack apertures are gradually reduced in the loading process,the permeability of rock sample will decrease progressively.This scenario shows that theoretical computation matches well with the experimental results.Finally,the effects of ratio of sample size to fracture aperture(n).pore pressure(P),and initial aperture(b) on stress-strain relationship and permeability change for contact compression fracture at closing stage are analyzed.展开更多
Although there are methods for testing the stress-strain relation and strength,which are the most fundamental and important properties of metallic materials,their application to small-volume materials and tube compone...Although there are methods for testing the stress-strain relation and strength,which are the most fundamental and important properties of metallic materials,their application to small-volume materials and tube components is lim-ited.In this study,based on energy density equivalence,a new dimensionless elastoplastic load-displacement model for compressed metal rings with isotropy and constitutive power law is proposed to describe the relations among the geometric dimensions,Hollomon law parameters,load,and displacement.Furthermore,a novel test method was developed to determine the elastic modulus,stress-strain relation,yield and tensile strength via ring compression test.The universality and accuracy of the method were verified within a wide range of imaginary materials using finite element analysis(FEA),and the results show that the stress-strain curves obtained by this method are consistent with those inputted in the FEA program.Additionally,a series of ring compression tests were performed for seven metallic materials.It was found that the stress-strain curves and mechanical properties predicted by the method agreed with the uniaxial tensile results.With its low material consumption,the ring compression test has the potential to be as an alternative to traditional tensile test when direct tension method is limited.展开更多
A micromechanics-based model is established. The model takes the interaction among sliding cracks into account, and it is able to quantify the effect of various parameters on the localization condition of damage and d...A micromechanics-based model is established. The model takes the interaction among sliding cracks into account, and it is able to quantify the effect of various parameters on the localization condition of damage and deformation for brittle rock subjected to compressive loads. The closed-form explicit expression for the complete stress-strain relation of rock containing microcracks subjected to compressive loads was obtained. It is showed that the complete stress-strain relation includes linear elasticity,nonlinear hardening,rapid stress drop and strain softening.The behavior of rapid stress drop and strain softening is due to localization of deformation and damage. Theoretical predictions have shown to be consistent with the experimental results.展开更多
Constitutive experiments are the base of all rock mechanics works. The effect of engineering character on constitutive law is a new problem of rock mechanics. The results of series specimens based on the uniaxial and ...Constitutive experiments are the base of all rock mechanics works. The effect of engineering character on constitutive law is a new problem of rock mechanics. The results of series specimens based on the uniaxial and plane strain compression experiments were presented and discussed. It is found that engineering or experiment character has obvious effects on stress-strain relationship and especially on mechanic parameters in post-peak area. And the law of size effect of softening materials was also discussed.展开更多
Objective: To observe the effect of simulated weightlessness on stress-strain relationship and the structural change of rabbit femoral vein. Methods: After seting up the Head-Down Tilt (-20°) (HDT) model to simul...Objective: To observe the effect of simulated weightlessness on stress-strain relationship and the structural change of rabbit femoral vein. Methods: After seting up the Head-Down Tilt (-20°) (HDT) model to simulate weightlessness, 24 healthy male New-Zealand Rabbits were randomly divided into HDT-21d group, HDT-10d group and control group, with 8 in each. Femoral venous strips and rings were used to make uniaxial tensile test of the longitudinal and circumferential specimens of the vessels. At last we observed the microstructure of femoral vein wall in 3 groups. Results : With the increasing of load stress, both longitudinal and circumferential strains of vein samples from 3 groups increased significantly (P<0. 01). With the decrease of unload stress, strains decrease obviously (P<0. 01). The unloaded longitudinal and the circumferential strain from 3 groups increased much than those of the loaded. Under the same stress (longitudinal 0-2. 0 g, circumferential 0. 5-1. 0 g) , HDT-21d group and HDT-10d group increased obviously in tlie longitudinal or circumferential strain (load and unload) than control, and HDT-21d increased much than that of HDT-10d. The contents and structures of femoral vein walls of HDT-rabbits changed significantly. Some endotheli-um cells of femoral vein became short, columnar or cubic even fell off. Smooth muscle layers became thinner. Conclusion:The compliance of femoral venous increased significantly after weightlessness-simulation and increased much obviously after 21d-HDT than that of 10 d. The structure of femoral vein wall changed obviously. The changes may be one reason for the increase of femoral vein compliance.展开更多
The recycled powder(RP)from construction wastes can be used to partially replace cement in the preparation of reactive powder concrete.In this paper,reactive powder concrete mixtures with RP partially replacing cement...The recycled powder(RP)from construction wastes can be used to partially replace cement in the preparation of reactive powder concrete.In this paper,reactive powder concrete mixtures with RP partially replacing cement,and natural sand instead of quartz,are developed.Standard curing is used,instead of steam curing that is normally requested by standard for reactive powder concrete.The influences of RP replacement ratio(0%,10%,20%,30%),silica fume proportion(10%,15%,20%),and steel fiber proportion(0%,1%,2%)are investigated.The effects of RP,silica fume,and steel fiber proportion on compressive strength,elastic modulus,and relative absorption energy are analyzed,and theoretical models for compressive strength,elastic modulus,and relative absorption energy are established.A constitutive model for the uniaxial compressive stress-strain relationship of reactive powder concrete with RP is developed.With the increase of RP replacement ratio from 0% to 30%,the compressive strength decreases by 42% and elastic modulus decreases by 24%.展开更多
Freeze-thaw damage gradients lead to non-uniform degradation of concrete mechanical properties at different depths.A study was conducted on the stress-strain relationship of stressed concrete with focus on the freeze-...Freeze-thaw damage gradients lead to non-uniform degradation of concrete mechanical properties at different depths.A study was conducted on the stress-strain relationship of stressed concrete with focus on the freeze-thaw damage gradient.The effects of relative freeze-thaw depths,number of freeze-thaw cycles(FTCs)and stress ratios on the stress-strain curves of concrete were analyzed.The test results demonstrated that freeze-thaw damage was more severe in the surface layers of concrete than in the deeper layers.The relative peak stress and strain of concrete degraded bilinearly with increasing depth.The stress-strain relationship of stressed concrete under FTC was established,and it was found to agree with the experimental results.展开更多
We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. ...We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.展开更多
Urban shrinkage has emerged as a widespread phenomenon globally and has a significant impact on land,particularly in terms of land use and price.This study focuses on 2851 county-level cities in China in 2005–2018(ex...Urban shrinkage has emerged as a widespread phenomenon globally and has a significant impact on land,particularly in terms of land use and price.This study focuses on 2851 county-level cities in China in 2005–2018(excluding Hong Kong,Macao,Taiwan,and‘no data’areas in Qinhai-Tibet Plateau)as the fundamental units of analysis.By employing nighttime light(NTL)data to identify shrinking cities,the propensity score matching(PSM)model was used to quantitatively examine the impact of shrinking cities on land prices,and evaluate the magnitude of this influence.The findings demonstrate the following:1)there were 613 shrinking cities in China,with moderate shrinkage being the most prevalent and severe shrinkage being the least.2)Regional disparities are evident in the spatial distribution of shrinking cities,especially in areas with diverse terrain.3)The spatial pattern of land price exhibits a significant correlated to the economic and administrative levels.4)Shrinking cities significantly negatively impact on the overall land price(ATT=–0.1241,P<0.05).However,the extent of the effect varies significantly among different spatial regions.This study contributes novel insights into the investigation of land prices and shrinking cities,ultimately serving as a foundation for government efforts to promote the sustainable development of urban areas.展开更多
How to use a few defect samples to complete the defect classification is a key challenge in the production of mobile phone screens.An attention-relation network for the mobile phone screen defect classification is pro...How to use a few defect samples to complete the defect classification is a key challenge in the production of mobile phone screens.An attention-relation network for the mobile phone screen defect classification is proposed in this paper.The architecture of the attention-relation network contains two modules:a feature extract module and a feature metric module.Different from other few-shot models,an attention mechanism is applied to metric learning in our model to measure the distance between features,so as to pay attention to the correlation between features and suppress unwanted information.Besides,we combine dilated convolution and skip connection to extract more feature information for follow-up processing.We validate attention-relation network on the mobile phone screen defect dataset.The experimental results show that the classification accuracy of the attentionrelation network is 0.9486 under the 5-way 1-shot training strategy and 0.9039 under the 5-way 5-shot setting.It achieves the excellent effect of classification for mobile phone screen defects and outperforms with dominant advantages.展开更多
The joint entity relation extraction model which integrates the semantic information of relation is favored by relevant researchers because of its effectiveness in solving the overlapping of entities,and the method of...The joint entity relation extraction model which integrates the semantic information of relation is favored by relevant researchers because of its effectiveness in solving the overlapping of entities,and the method of defining the semantic template of relation manually is particularly prominent in the extraction effect because it can obtain the deep semantic information of relation.However,this method has some problems,such as relying on expert experience and poor portability.Inspired by the rule-based entity relation extraction method,this paper proposes a joint entity relation extraction model based on a relation semantic template automatically constructed,which is abbreviated as RSTAC.This model refines the extraction rules of relation semantic templates from relation corpus through dependency parsing and realizes the automatic construction of relation semantic templates.Based on the relation semantic template,the process of relation classification and triplet extraction is constrained,and finally,the entity relation triplet is obtained.The experimental results on the three major Chinese datasets of DuIE,SanWen,and FinRE showthat the RSTAC model successfully obtains rich deep semantics of relation,improves the extraction effect of entity relation triples,and the F1 scores are increased by an average of 0.96% compared with classical joint extraction models such as CasRel,TPLinker,and RFBFN.展开更多
In this article, we study generating sets of the complete semigroups of binary relations defined by X-semilattices of unions of the class Σ<sub>8</sub>(X, 5). Found uniquely irreducible generating set for...In this article, we study generating sets of the complete semigroups of binary relations defined by X-semilattices of unions of the class Σ<sub>8</sub>(X, 5). Found uniquely irreducible generating set for the given semigroups and when X is finite set formulas for calculating the number of elements in generating sets are derived.展开更多
We explore the properties of the bottom-quark on-shell mass(M_(b))by using its relation to the MS mass(m_(b)).At present,this MS-on-shell relation has been known up to four-loop QCD corrections,which however still has...We explore the properties of the bottom-quark on-shell mass(M_(b))by using its relation to the MS mass(m_(b)).At present,this MS-on-shell relation has been known up to four-loop QCD corrections,which however still has a~2%scale uncertainty by taking the renormalization scale as m_(b)(m_(b))and varying it within the usual range of [m_(b)(m_(b))/2,2m_(b)(m_(b))].展开更多
In agreement with Titchmarsh’s theorem, we prove that dispersion relations are just the Fourier-transform of the identity, g(x′)=±Sgn(x′)g(x′), which defines the property of being a truncated functions at the...In agreement with Titchmarsh’s theorem, we prove that dispersion relations are just the Fourier-transform of the identity, g(x′)=±Sgn(x′)g(x′), which defines the property of being a truncated functions at the origin. On the other hand, we prove that the wave-function of a generalized diffraction in time problem is just the Fourier-transform of a truncated function. Consequently, the existence of dispersion relations for the diffraction in time wave-function follows. We derive these explicit dispersion relations.展开更多
Objectives:The arrival of cancer in adolescents and young adults(aged 15 to 24 years)-Adolescents and young adults(AJA)-corresponds to a fragile period during which the adulthood of the young person and the evolution ...Objectives:The arrival of cancer in adolescents and young adults(aged 15 to 24 years)-Adolescents and young adults(AJA)-corresponds to a fragile period during which the adulthood of the young person and the evolution of family ties mobilize the family as a whole.Therefore,cancer,beyond its individual traumatic dimension,affects the whole family,which can modify family ties and family functioning.Our objective is to evaluate family functioning from the complex model evaluating cohesion and adaptability when an adolescent or young adult has cancer.Methods:Adolescents and young adults with cancer(n=41),mothers(n=41),and fathers(n=13)participated in this study.They completed the Family Adaptation and Cohesion Scales(FACES Ⅲ)questionnaire.Family functioning when an aya is ill has been compared to that of families without any disease.Results:a comparison of the mean scores of perceived cohesion and adaptability of face Ⅲ indicates no significant difference for cohesion.In contrast,the averages of the adaptability scores of our sample with those of the general population indicate that families with cancer hais generally feel more“adaptable”than the non-clinical population.These results are statistically significant for AJA,but also for mothers and fathers.Regarding the mean scores of ideal cohesion and ideal adaptability,there are no significant differences between fathers in our sample and fathers in the general population.In contrast,mothers in our sample had less ideal adaptability than those in the general population.In aya patients with cancer,the scores of both adaptability and cohesion were significantly different from those of non-diseased adolescents.Conclusion:Cancer leads to many changes in family relationships,making it difficult to empower the young patient and latent the evolution of the relationship.展开更多
To solve the problem of long response time when users obtain suitable cutting parameters through the Internet based platform,a case-based reasoning framework is proposed.Specifically,a Hamming distance and Euclidean d...To solve the problem of long response time when users obtain suitable cutting parameters through the Internet based platform,a case-based reasoning framework is proposed.Specifically,a Hamming distance and Euclidean distance combined method is designed to measure the similarity of case features which have both numeric and category properties.In addition,AHP(Analytic Hierarchy Process)and entropy weight method are integrated to provide features weight,where both user preferences and comprehensive impact of the index have been concerned.Grey relation analysis is used to obtain the similarity of a new problem and alternative cases.Finally,a platform is also developed on Visual Studio 2015,and a case study is demonstrated to verify the practicality and efficiency of the proposed method.This method can obtain cutting parameters which is suitable without iterative calculation.Compared with the traditional PSO(Particle swarm optimization algorithm)and GA(Genetic algorithm),it can obtain faster response speed.This method can provide ideas for selecting processing parameters in industrial production.While guaranteeing the characteristic information is similar,this approach can select processing parameters which is the most appropriate for the production process and a lot of time can be saved.展开更多
Effective data communication is a crucial aspect of the Social Internet of Things(SIoT)and continues to be a significant research focus.This paper proposes a data forwarding algorithm based on Multidimensional Social ...Effective data communication is a crucial aspect of the Social Internet of Things(SIoT)and continues to be a significant research focus.This paper proposes a data forwarding algorithm based on Multidimensional Social Relations(MSRR)in SIoT to solve this problem.The proposed algorithm separates message forwarding into intra-and cross-community forwarding by analyzing interest traits and social connections among nodes.Three new metrics are defined:the intensity of node social relationships,node activity,and community connectivity.Within the community,messages are sent by determining which node is most similar to the sender by weighing the strength of social connections and node activity.When a node performs cross-community forwarding,the message is forwarded to the most reasonable relay community by measuring the node activity and the connection between communities.The proposed algorithm was compared to three existing routing algorithms in simulation experiments.Results indicate that the proposed algorithmsubstantially improves message delivery efficiency while lessening network overhead and enhancing connectivity and coordination in the SIoT context.展开更多
基金The project supported by the National Natural Science Foundation of China (19525207).
文摘As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be treated as a ma- terial of varying transverse isotropy. In this Part, the elastic stress-strain relations and the quadratic strength criterion are established in the form of having varying transverse isotropy, in the framework of micromechanics to take into account of the effect of the microstructures-dentin tubules. Simplified forms for isotropic and ho- mogeneous cases, as well as the corresponding plane stress form of the stress-strain relations are also given. These theoretical models are very well supported by the experiments shown later in the continued paper (Part Ⅱ).
基金Project(50608038) supported by the National Natural Science Foundation of China
文摘A moisture-content based constitutive model was proposed based on the hyperbolic model as an attempt to move towards the implementation of unsaturated soil mechanics into routine geotechnical engineering practice. The stress-strain behavior of in-situ soil at a depth of 5 m was investigated by conducting undrained triaxial compression tests using the remolded soil samples. The test results show that the stress-strain relationship of unsaturated cohesive soil is still hyperbolic. The values of parameters a and b given in the model decrease with increasing the confining pressure for soil samples with the same moisture content and increase with increasing the moisture content for soil samples under the same confining pressure. The relationships between parameters a, b and moisture content were studied for confining pressures of 100, 150, 200 and 250 kPa. The comparison between the measured and predicted stress-strain curves for an additional group of soil samples, having a moisture content of 25.4%, shows that the proposed moisture content-dependent hyperbolic model provides a good prediction of stress-strain behavior of unsaturated cohesive soil.
文摘The research of the failure criterion and one-dimensional stress-strain relationship of deteriorated concrete were carried out. Based on the damage mechanics theory, the dsmage which reflects the alternation of internal state of material were introduced into the formula presented by Desayi and Krishman and the weighted twin-shear strength theory. As a nondestructive examination method in common use, the ultrasonic technique was adopted in the study, and the ultrasonic velocity was used to establish the damage variable. After that, the failure criterion and one-dimensional stress-strain relationship for deteriorated concrete were obtained. Eventually, tests were carried out to study the evolution laws on the damage. The results show that the more freezing and thawing cycles are, the more apparently the failure surface shrinks. Meanwhile, the comparison between theoretical data and experimental data verifies tile rationality of tile damage-based one-dimensional stress-strain relationship proposed.
基金the National Natural Science Foundation of China(Grant Nos.51374215,11572343,51622404)Beijing Major Scientific and Technological Achievements into Ground Cultivation Project(Grant No.Z151100002815004)+2 种基金Fok Ying Tung Education Foundation(Grant No.142018)the State Key Research Development Program of China(Grant No.2016YFC0801404)Outstanding Young Talents of"Ten Thousand People Plan"
文摘Understanding the stress-strain relationship and permeability change for contact compression fracture at closing stage has been a hot issue for a long time.Previous investigations of this topic were mainly focused on experimental tests;however,theoretical approaches were rarely reported.Based on this,this paper focuses on the contact fracture at closing stage when rock is uniaxially loaded,and then a theoretical model is proposed.Based on the change of fracture elasticity modulus,it shows that as crack apertures are gradually reduced in the loading process,the permeability of rock sample will decrease progressively.This scenario shows that theoretical computation matches well with the experimental results.Finally,the effects of ratio of sample size to fracture aperture(n).pore pressure(P),and initial aperture(b) on stress-strain relationship and permeability change for contact compression fracture at closing stage are analyzed.
基金Supported by National Natural Science Foundation of China(Grant Nos.11872320 and 12072294)
文摘Although there are methods for testing the stress-strain relation and strength,which are the most fundamental and important properties of metallic materials,their application to small-volume materials and tube components is lim-ited.In this study,based on energy density equivalence,a new dimensionless elastoplastic load-displacement model for compressed metal rings with isotropy and constitutive power law is proposed to describe the relations among the geometric dimensions,Hollomon law parameters,load,and displacement.Furthermore,a novel test method was developed to determine the elastic modulus,stress-strain relation,yield and tensile strength via ring compression test.The universality and accuracy of the method were verified within a wide range of imaginary materials using finite element analysis(FEA),and the results show that the stress-strain curves obtained by this method are consistent with those inputted in the FEA program.Additionally,a series of ring compression tests were performed for seven metallic materials.It was found that the stress-strain curves and mechanical properties predicted by the method agreed with the uniaxial tensile results.With its low material consumption,the ring compression test has the potential to be as an alternative to traditional tensile test when direct tension method is limited.
文摘A micromechanics-based model is established. The model takes the interaction among sliding cracks into account, and it is able to quantify the effect of various parameters on the localization condition of damage and deformation for brittle rock subjected to compressive loads. The closed-form explicit expression for the complete stress-strain relation of rock containing microcracks subjected to compressive loads was obtained. It is showed that the complete stress-strain relation includes linear elasticity,nonlinear hardening,rapid stress drop and strain softening.The behavior of rapid stress drop and strain softening is due to localization of deformation and damage. Theoretical predictions have shown to be consistent with the experimental results.
基金National Naturnal Science Foundation of China(5010902)
文摘Constitutive experiments are the base of all rock mechanics works. The effect of engineering character on constitutive law is a new problem of rock mechanics. The results of series specimens based on the uniaxial and plane strain compression experiments were presented and discussed. It is found that engineering or experiment character has obvious effects on stress-strain relationship and especially on mechanic parameters in post-peak area. And the law of size effect of softening materials was also discussed.
基金Supported by Grant from the National Natural Science Foundation of China(30000197)
文摘Objective: To observe the effect of simulated weightlessness on stress-strain relationship and the structural change of rabbit femoral vein. Methods: After seting up the Head-Down Tilt (-20°) (HDT) model to simulate weightlessness, 24 healthy male New-Zealand Rabbits were randomly divided into HDT-21d group, HDT-10d group and control group, with 8 in each. Femoral venous strips and rings were used to make uniaxial tensile test of the longitudinal and circumferential specimens of the vessels. At last we observed the microstructure of femoral vein wall in 3 groups. Results : With the increasing of load stress, both longitudinal and circumferential strains of vein samples from 3 groups increased significantly (P<0. 01). With the decrease of unload stress, strains decrease obviously (P<0. 01). The unloaded longitudinal and the circumferential strain from 3 groups increased much than those of the loaded. Under the same stress (longitudinal 0-2. 0 g, circumferential 0. 5-1. 0 g) , HDT-21d group and HDT-10d group increased obviously in tlie longitudinal or circumferential strain (load and unload) than control, and HDT-21d increased much than that of HDT-10d. The contents and structures of femoral vein walls of HDT-rabbits changed significantly. Some endotheli-um cells of femoral vein became short, columnar or cubic even fell off. Smooth muscle layers became thinner. Conclusion:The compliance of femoral venous increased significantly after weightlessness-simulation and increased much obviously after 21d-HDT than that of 10 d. The structure of femoral vein wall changed obviously. The changes may be one reason for the increase of femoral vein compliance.
基金supported by National Key R&D Program of China(No.2022YFC3801100)the National Natural Science Foundation of China(Grant No.51208373)the Shanghai Pujiang Program(No.12PJ1409000).
文摘The recycled powder(RP)from construction wastes can be used to partially replace cement in the preparation of reactive powder concrete.In this paper,reactive powder concrete mixtures with RP partially replacing cement,and natural sand instead of quartz,are developed.Standard curing is used,instead of steam curing that is normally requested by standard for reactive powder concrete.The influences of RP replacement ratio(0%,10%,20%,30%),silica fume proportion(10%,15%,20%),and steel fiber proportion(0%,1%,2%)are investigated.The effects of RP,silica fume,and steel fiber proportion on compressive strength,elastic modulus,and relative absorption energy are analyzed,and theoretical models for compressive strength,elastic modulus,and relative absorption energy are established.A constitutive model for the uniaxial compressive stress-strain relationship of reactive powder concrete with RP is developed.With the increase of RP replacement ratio from 0% to 30%,the compressive strength decreases by 42% and elastic modulus decreases by 24%.
基金supported by the National Natural Science Foundation of China (Grant Nos.52178163 and 51808437)Xi'an Science and Technology Plan (No.22SFSF0005)+1 种基金the Key R&D Program of Shaanxi Province (No.2022SF-403)the China Scholarship Council (No.201908610062).
文摘Freeze-thaw damage gradients lead to non-uniform degradation of concrete mechanical properties at different depths.A study was conducted on the stress-strain relationship of stressed concrete with focus on the freeze-thaw damage gradient.The effects of relative freeze-thaw depths,number of freeze-thaw cycles(FTCs)and stress ratios on the stress-strain curves of concrete were analyzed.The test results demonstrated that freeze-thaw damage was more severe in the surface layers of concrete than in the deeper layers.The relative peak stress and strain of concrete degraded bilinearly with increasing depth.The stress-strain relationship of stressed concrete under FTC was established,and it was found to agree with the experimental results.
文摘We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.
基金Under the auspices of National Natural Science Foundation of China(No.42071222,41771194)。
文摘Urban shrinkage has emerged as a widespread phenomenon globally and has a significant impact on land,particularly in terms of land use and price.This study focuses on 2851 county-level cities in China in 2005–2018(excluding Hong Kong,Macao,Taiwan,and‘no data’areas in Qinhai-Tibet Plateau)as the fundamental units of analysis.By employing nighttime light(NTL)data to identify shrinking cities,the propensity score matching(PSM)model was used to quantitatively examine the impact of shrinking cities on land prices,and evaluate the magnitude of this influence.The findings demonstrate the following:1)there were 613 shrinking cities in China,with moderate shrinkage being the most prevalent and severe shrinkage being the least.2)Regional disparities are evident in the spatial distribution of shrinking cities,especially in areas with diverse terrain.3)The spatial pattern of land price exhibits a significant correlated to the economic and administrative levels.4)Shrinking cities significantly negatively impact on the overall land price(ATT=–0.1241,P<0.05).However,the extent of the effect varies significantly among different spatial regions.This study contributes novel insights into the investigation of land prices and shrinking cities,ultimately serving as a foundation for government efforts to promote the sustainable development of urban areas.
文摘How to use a few defect samples to complete the defect classification is a key challenge in the production of mobile phone screens.An attention-relation network for the mobile phone screen defect classification is proposed in this paper.The architecture of the attention-relation network contains two modules:a feature extract module and a feature metric module.Different from other few-shot models,an attention mechanism is applied to metric learning in our model to measure the distance between features,so as to pay attention to the correlation between features and suppress unwanted information.Besides,we combine dilated convolution and skip connection to extract more feature information for follow-up processing.We validate attention-relation network on the mobile phone screen defect dataset.The experimental results show that the classification accuracy of the attentionrelation network is 0.9486 under the 5-way 1-shot training strategy and 0.9039 under the 5-way 5-shot setting.It achieves the excellent effect of classification for mobile phone screen defects and outperforms with dominant advantages.
基金supported by the National Natural Science Foundation of China(Nos.U1804263,U1736214,62172435)the Zhongyuan Science and Technology Innovation Leading Talent Project(No.214200510019).
文摘The joint entity relation extraction model which integrates the semantic information of relation is favored by relevant researchers because of its effectiveness in solving the overlapping of entities,and the method of defining the semantic template of relation manually is particularly prominent in the extraction effect because it can obtain the deep semantic information of relation.However,this method has some problems,such as relying on expert experience and poor portability.Inspired by the rule-based entity relation extraction method,this paper proposes a joint entity relation extraction model based on a relation semantic template automatically constructed,which is abbreviated as RSTAC.This model refines the extraction rules of relation semantic templates from relation corpus through dependency parsing and realizes the automatic construction of relation semantic templates.Based on the relation semantic template,the process of relation classification and triplet extraction is constrained,and finally,the entity relation triplet is obtained.The experimental results on the three major Chinese datasets of DuIE,SanWen,and FinRE showthat the RSTAC model successfully obtains rich deep semantics of relation,improves the extraction effect of entity relation triples,and the F1 scores are increased by an average of 0.96% compared with classical joint extraction models such as CasRel,TPLinker,and RFBFN.
文摘In this article, we study generating sets of the complete semigroups of binary relations defined by X-semilattices of unions of the class Σ<sub>8</sub>(X, 5). Found uniquely irreducible generating set for the given semigroups and when X is finite set formulas for calculating the number of elements in generating sets are derived.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.12175025,12247129,and 12347101)the Graduate Research and Innovation Foundation of Chongqing,China(Grant No.ydstd1912)the Foundation of Chongqing Normal University(Grant No.24XLB015)。
文摘We explore the properties of the bottom-quark on-shell mass(M_(b))by using its relation to the MS mass(m_(b)).At present,this MS-on-shell relation has been known up to four-loop QCD corrections,which however still has a~2%scale uncertainty by taking the renormalization scale as m_(b)(m_(b))and varying it within the usual range of [m_(b)(m_(b))/2,2m_(b)(m_(b))].
文摘In agreement with Titchmarsh’s theorem, we prove that dispersion relations are just the Fourier-transform of the identity, g(x′)=±Sgn(x′)g(x′), which defines the property of being a truncated functions at the origin. On the other hand, we prove that the wave-function of a generalized diffraction in time problem is just the Fourier-transform of a truncated function. Consequently, the existence of dispersion relations for the diffraction in time wave-function follows. We derive these explicit dispersion relations.
文摘Objectives:The arrival of cancer in adolescents and young adults(aged 15 to 24 years)-Adolescents and young adults(AJA)-corresponds to a fragile period during which the adulthood of the young person and the evolution of family ties mobilize the family as a whole.Therefore,cancer,beyond its individual traumatic dimension,affects the whole family,which can modify family ties and family functioning.Our objective is to evaluate family functioning from the complex model evaluating cohesion and adaptability when an adolescent or young adult has cancer.Methods:Adolescents and young adults with cancer(n=41),mothers(n=41),and fathers(n=13)participated in this study.They completed the Family Adaptation and Cohesion Scales(FACES Ⅲ)questionnaire.Family functioning when an aya is ill has been compared to that of families without any disease.Results:a comparison of the mean scores of perceived cohesion and adaptability of face Ⅲ indicates no significant difference for cohesion.In contrast,the averages of the adaptability scores of our sample with those of the general population indicate that families with cancer hais generally feel more“adaptable”than the non-clinical population.These results are statistically significant for AJA,but also for mothers and fathers.Regarding the mean scores of ideal cohesion and ideal adaptability,there are no significant differences between fathers in our sample and fathers in the general population.In contrast,mothers in our sample had less ideal adaptability than those in the general population.In aya patients with cancer,the scores of both adaptability and cohesion were significantly different from those of non-diseased adolescents.Conclusion:Cancer leads to many changes in family relationships,making it difficult to empower the young patient and latent the evolution of the relationship.
基金the Sichuan Science and Technology Program(Nos.23ZHCG0049,2023YFG0078,23ZHCG0030,2021ZDZX0007)SCU-SUINING Project(2022CDSN-14).
文摘To solve the problem of long response time when users obtain suitable cutting parameters through the Internet based platform,a case-based reasoning framework is proposed.Specifically,a Hamming distance and Euclidean distance combined method is designed to measure the similarity of case features which have both numeric and category properties.In addition,AHP(Analytic Hierarchy Process)and entropy weight method are integrated to provide features weight,where both user preferences and comprehensive impact of the index have been concerned.Grey relation analysis is used to obtain the similarity of a new problem and alternative cases.Finally,a platform is also developed on Visual Studio 2015,and a case study is demonstrated to verify the practicality and efficiency of the proposed method.This method can obtain cutting parameters which is suitable without iterative calculation.Compared with the traditional PSO(Particle swarm optimization algorithm)and GA(Genetic algorithm),it can obtain faster response speed.This method can provide ideas for selecting processing parameters in industrial production.While guaranteeing the characteristic information is similar,this approach can select processing parameters which is the most appropriate for the production process and a lot of time can be saved.
基金supported by the NationalNatural Science Foundation of China(61972136)the Hubei Provincial Department of Education Outstanding Youth Scientific Innovation Team Support Foundation(T201410,T2020017)+1 种基金the Natural Science Foundation of Xiaogan City(XGKJ2022010095,XGKJ2022010094)the Science and Technology Research Project of Education Department of Hubei Province(No.Q20222704).
文摘Effective data communication is a crucial aspect of the Social Internet of Things(SIoT)and continues to be a significant research focus.This paper proposes a data forwarding algorithm based on Multidimensional Social Relations(MSRR)in SIoT to solve this problem.The proposed algorithm separates message forwarding into intra-and cross-community forwarding by analyzing interest traits and social connections among nodes.Three new metrics are defined:the intensity of node social relationships,node activity,and community connectivity.Within the community,messages are sent by determining which node is most similar to the sender by weighing the strength of social connections and node activity.When a node performs cross-community forwarding,the message is forwarded to the most reasonable relay community by measuring the node activity and the connection between communities.The proposed algorithm was compared to three existing routing algorithms in simulation experiments.Results indicate that the proposed algorithmsubstantially improves message delivery efficiency while lessening network overhead and enhancing connectivity and coordination in the SIoT context.
