This article compares the constitution theory of Huangdi Neijing 《黄帝内经》 and Hippocrates Corpus 《希波克拉底文集》 from three aspects:theory,philosophical ideas,and influence on later generations,to analyze the s...This article compares the constitution theory of Huangdi Neijing 《黄帝内经》 and Hippocrates Corpus 《希波克拉底文集》 from three aspects:theory,philosophical ideas,and influence on later generations,to analyze the similarities and differences between two medical systems representing TCM and Western medicine in their early stages of origin.From the comparison and analysis of two books’ history,specific theories in constitution,philosophical characteristics and values in history,we can have a deeper perspective to compare TCM and Western medicine,and have a clearer idea for the development of integrated traditional Chinese and Western medicine.展开更多
This paper expounds the theory of traditional Chinese medicine(TCM)constitution applied to patients with cervical spondylosis,in order to clarify the distribution characteristics of TCM constitution of patients with c...This paper expounds the theory of traditional Chinese medicine(TCM)constitution applied to patients with cervical spondylosis,in order to clarify the distribution characteristics of TCM constitution of patients with cervical spondylosis.And to analyze the correlation between TCM constitution theory and cervical spondylosis is helpful to provide ideas for integrated nursing care of TCM and western medicine in patients with cervical spondylosis,and provide the basis for the construction of health management program and the evaluation of health promotion effect.展开更多
Highly entangled hydrogels exhibit excellent mechanical properties,including high toughness,high stretchability,and low hysteresis.By considering the evolution of randomly distributed entanglements within the polymer ...Highly entangled hydrogels exhibit excellent mechanical properties,including high toughness,high stretchability,and low hysteresis.By considering the evolution of randomly distributed entanglements within the polymer network upon mechanical stretches,we develop a constitutive theory to describe the large stretch behaviors of these hydrogels.In the theory,we utilize a representative volume element(RVE)in the shape of a cube,within which there exists an averaged chain segment along each edge and a mobile entanglement at each corner.By employing an explicit method,we decouple the elasticity of the hydrogels from the sliding motion of their entanglements,and derive the stress-stretch relations for these hydrogels.The present theoretical analysis is in agreement with experiment,and highlights the significant influence of the entanglement distribution within the hydrogels on their elasticity.We also implement the present developed constitutive theory into a commercial finite element software,and the subsequent simulations demonstrate that the exact distribution of entanglements strongly affects the mechanical behaviors of the structures of these hydrogels.Overall,the present theory provides valuable insights into the deformation mechanism of highly entangled hydrogels,and can aid in the design of these hydrogels with enhanced performance.展开更多
Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the t...Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the two. To analyze acoustic-induced deformation of soft materials, we establish an acoustomechanical constitutive theory by combining the acoustic radiation stress theory and the nonlinear elasticity theory for soft materials. The acoustic radiation stress tensor is formulated by time averaging the momentum equation of particle motion, which is then introduced into the nonlinear elasticity constitutive relation to construct the acoustomechanical constitutive theory for soft materials.Considering a specified case of soft material sheet subjected to two counter-propagating acoustic waves, we demonstrate the nonlinear large deformation of the soft material and analyze the interaction between acoustic waves and material deformation under the conditions of total reflection, acoustic transparency, and acoustic mismatch.展开更多
In this study, the behavior of polycrystalline metals at different temperatures is investigated by a new thermo-elasto-plasticity constitutive theory. Based on solid mechanical and interatomic potential, the constitut...In this study, the behavior of polycrystalline metals at different temperatures is investigated by a new thermo-elasto-plasticity constitutive theory. Based on solid mechanical and interatomic potential, the constitutive equa- tion is established using a new decomposition of the deformation gradient. For polycrystalline copper and magnesium, the stress-strain curves from 77 to 764 K (copper), and 77 to 870 K (magnesium) under quasi-static uniaxial loading are calculated, and then the calculated results are compared with the experiment results. Also, it is determined that the present model has the capacity to describe the decrease of the elastic modulus and yield stress with the increasing temperature, as well as the change of hardening behaviors of the polycrystalline metals. The calculation process is simple and explicit, which makes it easy to implement into the applications.展开更多
A microstructural constitutive theory of ER suspensions was formulated in this investigation. The framework was based on the internal variable theory and the mechanism analysis. The ER suspension consists of fine part...A microstructural constitutive theory of ER suspensions was formulated in this investigation. The framework was based on the internal variable theory and the mechanism analysis. The ER suspension consists of fine particles with high dielectric constant and the supporting fluid. Under the action of the electric field, the polarized particles will aggregate together to form the chain-like structures along the direction of the electric field. As the size and orientation of the particle aggregates are volatile, and they adjust according to the applied electric field and strain rate, the energy conservation equation and the force equilibrium equation were thus established to determine the orientation and size of the aggregates. Following that, a three-dimensional, explicit form of the constitutive equation was derived based on the interaction energy and the dissipation function of the system. The response of the system under the action of a simple shearing load was considered and discussed in detail. It is found that the shear-thinning viscosity of an ER suspension is wed approximated by the power-law proportional to (Mn)(-D.82).展开更多
Buckling of a woven fabric is analyzed in this paper when it is subjected to a simple shear in warp direction.The equation to determine the buckling direction (buckling wave direction) is obtained and it is found that...Buckling of a woven fabric is analyzed in this paper when it is subjected to a simple shear in warp direction.The equation to determine the buckling direction (buckling wave direction) is obtained and it is found that the buckling direction is related to the critical amount of shear.It is shown that the out-of-plane buckling of fabric is possible and only a flexural buckling mode can exist.The buckling condition for flexural mode is obtained and the curve for that is illustrated.展开更多
The patterns of modern science and changes in the medical model can result in the transformation of the current state of individualized and health medicines into being the primary trend in medical development.Chinese ...The patterns of modern science and changes in the medical model can result in the transformation of the current state of individualized and health medicines into being the primary trend in medical development.Chinese and Western medical systems are dissimilar in terms of value orientations,thinking style,and research directions because of their different historical and cultural backgrounds.Individualized treatment in modern medicine is mainly established based on individual genome information and the differences in mononucleotide polymorphisms.However,such treatment method is expensive,creates an uncertain genetic marker,and leads to different result interpretations,among other problems.The Chinese constitutional theory developed in the 1970s expresses the principle behind Chinese health medicine and individual treatment and provides the corresponding methods.The Chinese constitutional theory divides the constitution of the Chinese population into nine categories based on established classification criteria.It promotes the study of the relationship of each constitution to diseases and Chinese medicine preparation toward adjusting the constitution and preventing diseases.The theory also provides methods and tools for individualized treatment.Constitution identification shows the direction and provides the core technology for the evaluation of the health status.By combining the developments in modern biotechnology,new diagnostic techniques and treatment models of constitution-differentiation,disease-differentiation,and syndrome-differentiation can be established for the development of individualized Chinese medicine treatment and health medicine for the international medical community.展开更多
The typical micro-knitting structure of knitted fabric,which makes it very different from woven fabric,is described.The tensile tests of knitted fabric are reported.The deformations of the micro-knitting structures ar...The typical micro-knitting structure of knitted fabric,which makes it very different from woven fabric,is described.The tensile tests of knitted fabric are reported.The deformations of the micro-knitting structures are carefully studied.The study indicates that when a knitted fabric sheet is subjected to a tension along w-direction an extra compressive stress field inside loop in c-direction is induced.The extra stress field is also determined through analysis.Finally,a micro-mechanical model of knitted fabric is proposed.This work paves the way for the simulations of buckling modes of a knitted fabric sheet as are observed in experiments.展开更多
Based on uniaxial experimental data of a nickel-based superalloy Udimet 720Li under monotonic tension, symmetrically cyclic loading and creep loading, the paper studied to utilize the Bodner-Partom unified constitutiv...Based on uniaxial experimental data of a nickel-based superalloy Udimet 720Li under monotonic tension, symmetrically cyclic loading and creep loading, the paper studied to utilize the Bodner-Partom unified constitutive theory to model the mechanical behaviors of the material under these three different loading conditions for the first time. After detailed analysis of the constitutive characteristics of the unified equations, a systematically optimized strategy was proposed to obtain material parameters in the equations. Thereafter, the B-P model was implemented into ABAQUS through UMAT subroutine and was employed to calculate inelastic responses of the material for different uniaxial loading cases at 700℃. Theoretical predictions are compared to experimental data and good agreement is generated.展开更多
Using the Splitting Hopkinson Pressure Bar (SHPB) experimental system, investigations were made into the dynamic mechanical performances of underground soft rocks. The experiments proved that the measured stress-str...Using the Splitting Hopkinson Pressure Bar (SHPB) experimental system, investigations were made into the dynamic mechanical performances of underground soft rocks. The experiments proved that the measured stress-strain curves display the characteristics of plastic deformation. By making use of a revised overstress constitutive formula for the stress model and by taking into account that the strain rate and strain are a function of I - E(t)/Eo, a revised overstress constitutive formula for the stress model was simplified by applying dimensional analysis and consequently, a simplified overstress formula was obtained for the stress model. Then, by taking into consideration the effects of damage under a dynamic load on the dynamic loading strength of the rock, the continuous damage theory and the statistical strength theory were introduced into the development of the simplified overstress constitutive formula for the stress model. Hence, a damage-based constitutive formula for an overstress model, which can be appropriately applied to the analysis of full dynamic stress-strain curves, was developed. By using the simplified damage-based constitutive formula for an overstress model, the actually measured curves are fitted, indicating that the fitting curves and those actually measured are in good agreement.展开更多
Based on the non-equilibrium thermodynamic theory, a new thermo-viscoelastic constitutive model for an incompressible material is proposed. This model can be considered as a kind of generalization of the non-Gaussian ...Based on the non-equilibrium thermodynamic theory, a new thermo-viscoelastic constitutive model for an incompressible material is proposed. This model can be considered as a kind of generalization of the non-Gaussian network theory in rubber elasticity to include the viscous and the thermal effects. A set of second rank tensorial internal variables was introduced, and in order to adequately describe the evolution of these internal variables, a new expression of the Helmholtz free energy was suggested. The mechanical behavior of the thermo-viscoelastic material under simple shear deformation was studied, and the “viscous dissipation induced” anisotropy due to the change of orientation distribution of molecular chains was examined. Influences of strain rate and thermal softening produced by the viscous dissipation on the shear stress were also discussed. Finally, the model predictions were compared with the experimental results performed by G'Sell et al., thus the validity of the proposed model is verified.展开更多
This paper presents ordered rate nonlinear constitutive theories for thermoviscoelastic fluids based on Classical Continuum Mechanics (CCM). We refer to these fluids as classical thermoviscoelastic polymeric fluids. T...This paper presents ordered rate nonlinear constitutive theories for thermoviscoelastic fluids based on Classical Continuum Mechanics (CCM). We refer to these fluids as classical thermoviscoelastic polymeric fluids. The conservation and balance laws of CCM constitute the core of the mathematical model. Constitutive theories for the Cauchy stress tensor are derived using the conjugate pair in the entropy inequality, additional desired physics, and the representation theorem. The constitutive theories for the Cauchy stress tensor consider convected time derivatives of Green’s strain tensor or the Almansi strain tensor up to order n and the convected time derivatives of the Cauchy stress tensor up to order m. The resulting constitutive theories of order (m, n) are based on integrity and are valid for dilute as well as dense polymeric, compressible, and incompressible fluids with variable material coefficients. It is shown that Maxwell, Oldroyd-B, and Giesekus constitutive models can be described by a single constitutive theory. It is well established that the currently used Maxwell and Oldroyd-B models predict zero normal stress perpendicular to the flow direction. It is shown that this deficiency is a consequence of not retaining certain generators and invariants from the integrity (complete basis) in the constitutive theory and can be corrected by including additional generators and invariants in the constitutive theory. Similar improvements are also suggested for the Giesekus constitutive model. Model problem studies are presented for BVPs consisting of fully developed flow between parallel plates and lid-driven cavities utilizing the new constitutive theories for Maxwell, Oldroyd-B, and Giesekus fluids. Results are compared with those obtained from using currently used constitutive theories for the three polymeric fluids.展开更多
In recent papers, Surana et al. presented internal polar non-classical Continuum theory in which velocity gradient tensor in its entirety was incorporated in the conservation and balance laws. Thus, this theory incorp...In recent papers, Surana et al. presented internal polar non-classical Continuum theory in which velocity gradient tensor in its entirety was incorporated in the conservation and balance laws. Thus, this theory incorporated symmetric part of the velocity gradient tensor (as done in classical theories) as well as skew symmetric part representing varying internal rotation rates between material points which when resisted by deforming continua result in dissipation (and/or storage) of mechanical work. This physics referred as internal polar physics is neglected in classical continuum theories but can be quite significant for some materials. In another recent paper Surana et al. presented ordered rate constitutive theories for internal polar non-classical fluent continua without memory derived using deviatoric Cauchy stress tensor and conjugate strain rate tensors of up to orders n and Cauchy moment tensor and its conjugate symmetric part of the first convected derivative of the rotation gradient tensor. In this constitutive theory higher order convected derivatives of the symmetric part of the rotation gradient tensor are assumed not to contribute to dissipation. Secondly, the skew symmetric part of the velocity gradient tensor is used as rotation rates to determine rate of rotation gradient tensor. This is an approximation to true convected time derivatives of the rotation gradient tensor. The resulting constitutive theory: (1) is incomplete as it neglects the second and higher order convected time derivatives of the symmetric part of the rotation gradient tensor;(2) first convected derivative of the symmetric part of the rotation gradient tensor as used by Surana et al. is only approximate;(3) has inconsistent treatment of dissipation due to Cauchy moment tensor when compared with the dissipation mechanism due to deviatoric part of symmetric Cauchy stress tensor in which convected time derivatives of up to order n are considered in the theory. The purpose of this paper is to present ordered rate constitutive theories for deviatoric Cauchy strain tensor, moment tensor and heat vector for thermofluids without memory in which convected time derivatives of strain tensors up to order n are conjugate with the Cauchy stress tensor and the convected time derivatives of the symmetric part of the rotation gradient tensor up to orders 1n are conjugate with the moment tensor. Conservation and balance laws are used to determine the choice of dependent variables in the constitutive theories: Helmholtz free energy density Φ, entropy density η, Cauchy stress tensor, moment tensor and heat vector. Stress tensor is decomposed into symmetric and skew symmetric parts and the symmetric part of the stress tensor and the moment tensor are further decomposed into equilibrium and deviatoric tensors. It is established through conjugate pairs in entropy inequality that the constitutive theories only need to be derived for symmetric stress tensor, moment tensor and heat vector. Density in the current configuration, convected time derivatives of the strain tensor up to order n, convected time derivatives of the symmetric part of the rotation gradient tensor up to orders 1n, temperature gradient tensor and temperature are considered as argument tensors of all dependent variables in the constitutive theories based on entropy inequality and principle of equipresence. The constitutive theories are derived in contravariant and covariant bases as well as using Jaumann rates. The nth and 1nth order rate constitutive theories for internal polar non-classical thermofluids without memory are specialized for n = 1 and 1n = 1 to demonstrate fundamental differences in the constitutive theories presented here and those used presently for classical thermofluids without memory and those published by Surana et al. for internal polar non-classical incompressible thermofluids.展开更多
Objective: To observe the clinical efficacy of acupuncture plus bloodletting therapy in treating insomnia in people with blood stasis constitution. Methods: Seventy-two patients were randomized into a treatment grou...Objective: To observe the clinical efficacy of acupuncture plus bloodletting therapy in treating insomnia in people with blood stasis constitution. Methods: Seventy-two patients were randomized into a treatment group and a control group by using the random number table, 36 cases each. The treatment group received acupuncture plus bloodletting therapy, while the control group was intervened by oral administration of estazolam. One-week treatment was taken as a course, for 3 successive courses in total. A follow-up study was conducted 3 months later. The Pittsburgh sleep quality index (PSQI) was evaluated before and after the intervention, as well as in the follow-up. The clinical efficacies were also compared. Results: The total effective rate was 88.9% in the treatment group versus 83.3% in the control group, and the between-group difference was statistically significant (P〈0.O5). After the intervention, the PSO.I scores dropped significantly in both groups (both P〈0.05); the between-group difference in PSQI score was statistically significant (P〈O.05). The follow-up study showed that the between-group difference in the global score of PSO, I was statistically significant (P〈0.05). Conclusion: Acupuncture plus bloodletting therapy can produce a more significant efficacy than oral administration of estazolam in treating insomnia in people with blood stasis constitution.展开更多
OBJECTIVE:Yang-deficiency constitution(YADC)is a common unbalanced constitution that predisposes individuals to certain diseases.However,not all people with YADC manifest develop diseases.This calls for delineation of...OBJECTIVE:Yang-deficiency constitution(YADC)is a common unbalanced constitution that predisposes individuals to certain diseases.However,not all people with YADC manifest develop diseases.This calls for delineation of the underlying molecular mechanisms.Previous studies suggested that the gut microbiota and gene differential expression should be considered.METHODS:In the present study,we compared profiles of gut microbiota between four healthy YADC individuals and those of five healthy balanced constitution(BC)counterparts,based on 16 S r RNA gene sequence analysis.Furthermore,YADC relevant genes identified by comparing 62 healthy YADC and 58 healthy BC individuals in total to perform intersection analysis,functional clustering and pathway enrichment analyses.RESULTS:The levels of harmful gut microbiota(Prevotellaceae,LDA score>4.0,P=0.0141)and beneficial gut microbiota(Ruminococcaceae,LDA score>4.0,P=0.0025,Faecalibacterium,LDA score>4.0,P=0.0484)were both elevated in healthy YADC individuals.Also,we found that the specific metabolic pathway with 2,6-Dichloro-p-hydroquinone 1,2-Dioxygenase(Pcp A)as the core in gut microbiota and the glutathione transferase activity has been enriched by YADC relevant genes in healthy YADC individuals were both responsible for the detoxification of halogenated aromatic hydrocarbon substances.CONCLUSIONS:Both beneficial and harmful factors had been detected in healthy YADC individuals,functionally,they may have triggered homeostasis to maintain the health of individuals with YADC.The homeostasis may be maintained by beneficial and harmful factors from gut flora and genes.Future studies are expected to focus on halogenated aromatic hydrocarbons and their detoxification processes.展开更多
For the Reynolds-stress closures in turbulence modelling, a constitutive theory is developed based on the principle of frame indifference and the theory of invariants. The present study sheds light on existing closure...For the Reynolds-stress closures in turbulence modelling, a constitutive theory is developed based on the principle of frame indifference and the theory of invariants. The present study sheds light on existing closure models and is instructive to developing new closure relations.展开更多
Micromorphic theory(MMT)envisions a material body as a continuous collection of deformable particles;each possesses finite size and inner structure.It is considered as the most successful top-down formulation of a two...Micromorphic theory(MMT)envisions a material body as a continuous collection of deformable particles;each possesses finite size and inner structure.It is considered as the most successful top-down formulation of a two-level continuum model,in which the deformation is expressed as a sum of macroscopic continuous deformation and internal microscopic deformation of the inner structure.In this work,the kinematics including the objective Eringen tensors is introduced.Balance laws are derived by requiring the energy equation to be form-invariant under the generalized Galilean transformation.The concept of material force and the balance law of pseudomomentum are generalized for MMT.An axiomatic approach is demonstrated in the formulation of constitutive equations for a generalized micromorphic thermoviscoelastic solid,generalized micromorphic fluid,micromorphic plasticity,and micromorphic electromagnetic-thermoelastic solid.Applications of MMT in micro/nanoscale are discussed.展开更多
Objective: To observe the effect of acupuncture for children with attention deficit hyperactivity disorder (ADHD). Methods: A total of 36 cases were recruited in this study. Before treatment, a Chinese medical con...Objective: To observe the effect of acupuncture for children with attention deficit hyperactivity disorder (ADHD). Methods: A total of 36 cases were recruited in this study. Before treatment, a Chinese medical constitution survey was conducted on these children. Based on the survey findings, the children were divided in different groups for acupuncture intervention. Additionally, the heart rate variability and attention were detected respectively before treatment, in the 12th and 24th week after treatment. Results: ADHD kids commonly manifest as a body constitution of yang predominance and heat exuberance. The kids' Body Mass Indexes (BMI) are moderately correlated with attention deficit disorder (ADD). After the treatment of 24 weeks, the ADHD scores were reduced from (10.94±1.98) to (8.56±2.48), showing a statistical significance (P〈0.05); in addition, the low frequency/high frequency (LF/HF) and normalized low frequency (nLF) between the two groups were also statistically different (P〈0.05). Conclusion: Most ADHD kids present with a body constitution of yang predominance and heat exuberance. A well-controlled BMI is helpful for ADHD treatment. Acupuncture can be a supplementary therapy to improve the ADHD symptoms.展开更多
The elasto-plastic-damage behavior of anisotropic aluminum alloys is investigated under finite deformation using a physical mechanism based constitutive model.With an application to the structural calculation,the pres...The elasto-plastic-damage behavior of anisotropic aluminum alloys is investigated under finite deformation using a physical mechanism based constitutive model.With an application to the structural calculation,the present model is used to describe and analyze the mechanical response of anisotropic 6260-T6 aluminum alloy extrusions.For the tensile specimens extracted along three different material orientations from the extruded aluminum profile,twelve simulations are carried out covering four different specimen geometries.The simulation results in force-displacement response and central logarithmic axial strain evolution are compared with experimental results.From the comparisons,it can be concluded that the present model has the capacity to describe the behavior of anisotropic material.From the force-displacement curves,the anisotropy is observed in different material orientations,and the physical mechanism of anisotropy is analyzed.展开更多
文摘This article compares the constitution theory of Huangdi Neijing 《黄帝内经》 and Hippocrates Corpus 《希波克拉底文集》 from three aspects:theory,philosophical ideas,and influence on later generations,to analyze the similarities and differences between two medical systems representing TCM and Western medicine in their early stages of origin.From the comparison and analysis of two books’ history,specific theories in constitution,philosophical characteristics and values in history,we can have a deeper perspective to compare TCM and Western medicine,and have a clearer idea for the development of integrated traditional Chinese and Western medicine.
文摘This paper expounds the theory of traditional Chinese medicine(TCM)constitution applied to patients with cervical spondylosis,in order to clarify the distribution characteristics of TCM constitution of patients with cervical spondylosis.And to analyze the correlation between TCM constitution theory and cervical spondylosis is helpful to provide ideas for integrated nursing care of TCM and western medicine in patients with cervical spondylosis,and provide the basis for the construction of health management program and the evaluation of health promotion effect.
基金Project supported by the Key Research Project of Zhejiang Laboratory (No.K2022NB0AC03)the National Natural Science Foundation of China (No.11872334)the National Natural Science Foundation of Zhejiang Province of China (No.LZ23A020004)。
文摘Highly entangled hydrogels exhibit excellent mechanical properties,including high toughness,high stretchability,and low hysteresis.By considering the evolution of randomly distributed entanglements within the polymer network upon mechanical stretches,we develop a constitutive theory to describe the large stretch behaviors of these hydrogels.In the theory,we utilize a representative volume element(RVE)in the shape of a cube,within which there exists an averaged chain segment along each edge and a mobile entanglement at each corner.By employing an explicit method,we decouple the elasticity of the hydrogels from the sliding motion of their entanglements,and derive the stress-stretch relations for these hydrogels.The present theoretical analysis is in agreement with experiment,and highlights the significant influence of the entanglement distribution within the hydrogels on their elasticity.We also implement the present developed constitutive theory into a commercial finite element software,and the subsequent simulations demonstrate that the exact distribution of entanglements strongly affects the mechanical behaviors of the structures of these hydrogels.Overall,the present theory provides valuable insights into the deformation mechanism of highly entangled hydrogels,and can aid in the design of these hydrogels with enhanced performance.
基金supported by the National Natural Science Foundation of China (Grants 51528501, 11532009)the Fundamental Research Funds for Central Universities (Grant 2014qngz12)supported by China Scholarship Council as a visiting scholar to Harvard University
文摘Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the two. To analyze acoustic-induced deformation of soft materials, we establish an acoustomechanical constitutive theory by combining the acoustic radiation stress theory and the nonlinear elasticity theory for soft materials. The acoustic radiation stress tensor is formulated by time averaging the momentum equation of particle motion, which is then introduced into the nonlinear elasticity constitutive relation to construct the acoustomechanical constitutive theory for soft materials.Considering a specified case of soft material sheet subjected to two counter-propagating acoustic waves, we demonstrate the nonlinear large deformation of the soft material and analyze the interaction between acoustic waves and material deformation under the conditions of total reflection, acoustic transparency, and acoustic mismatch.
基金supported by the National Natural Science Foundation of China (Grants 11021262, 11172303, 11132011)National Basic Research Program of China through 2012CB937500
文摘In this study, the behavior of polycrystalline metals at different temperatures is investigated by a new thermo-elasto-plasticity constitutive theory. Based on solid mechanical and interatomic potential, the constitutive equa- tion is established using a new decomposition of the deformation gradient. For polycrystalline copper and magnesium, the stress-strain curves from 77 to 764 K (copper), and 77 to 870 K (magnesium) under quasi-static uniaxial loading are calculated, and then the calculated results are compared with the experiment results. Also, it is determined that the present model has the capacity to describe the decrease of the elastic modulus and yield stress with the increasing temperature, as well as the change of hardening behaviors of the polycrystalline metals. The calculation process is simple and explicit, which makes it easy to implement into the applications.
文摘A microstructural constitutive theory of ER suspensions was formulated in this investigation. The framework was based on the internal variable theory and the mechanism analysis. The ER suspension consists of fine particles with high dielectric constant and the supporting fluid. Under the action of the electric field, the polarized particles will aggregate together to form the chain-like structures along the direction of the electric field. As the size and orientation of the particle aggregates are volatile, and they adjust according to the applied electric field and strain rate, the energy conservation equation and the force equilibrium equation were thus established to determine the orientation and size of the aggregates. Following that, a three-dimensional, explicit form of the constitutive equation was derived based on the interaction energy and the dissipation function of the system. The response of the system under the action of a simple shearing load was considered and discussed in detail. It is found that the shear-thinning viscosity of an ER suspension is wed approximated by the power-law proportional to (Mn)(-D.82).
基金Supported by National Natural Science Foundation of China!(No.1 9772 0 32 )
文摘Buckling of a woven fabric is analyzed in this paper when it is subjected to a simple shear in warp direction.The equation to determine the buckling direction (buckling wave direction) is obtained and it is found that the buckling direction is related to the critical amount of shear.It is shown that the out-of-plane buckling of fabric is possible and only a flexural buckling mode can exist.The buckling condition for flexural mode is obtained and the curve for that is illustrated.
基金This work was supported by grants from the National Basic Research Program of China(No.2011CB505400,the study of Chinese medical original thought and health identification methods system).
文摘The patterns of modern science and changes in the medical model can result in the transformation of the current state of individualized and health medicines into being the primary trend in medical development.Chinese and Western medical systems are dissimilar in terms of value orientations,thinking style,and research directions because of their different historical and cultural backgrounds.Individualized treatment in modern medicine is mainly established based on individual genome information and the differences in mononucleotide polymorphisms.However,such treatment method is expensive,creates an uncertain genetic marker,and leads to different result interpretations,among other problems.The Chinese constitutional theory developed in the 1970s expresses the principle behind Chinese health medicine and individual treatment and provides the corresponding methods.The Chinese constitutional theory divides the constitution of the Chinese population into nine categories based on established classification criteria.It promotes the study of the relationship of each constitution to diseases and Chinese medicine preparation toward adjusting the constitution and preventing diseases.The theory also provides methods and tools for individualized treatment.Constitution identification shows the direction and provides the core technology for the evaluation of the health status.By combining the developments in modern biotechnology,new diagnostic techniques and treatment models of constitution-differentiation,disease-differentiation,and syndrome-differentiation can be established for the development of individualized Chinese medicine treatment and health medicine for the international medical community.
基金The project supported by the National Natural Science Foundation of China(10272079)
文摘The typical micro-knitting structure of knitted fabric,which makes it very different from woven fabric,is described.The tensile tests of knitted fabric are reported.The deformations of the micro-knitting structures are carefully studied.The study indicates that when a knitted fabric sheet is subjected to a tension along w-direction an extra compressive stress field inside loop in c-direction is induced.The extra stress field is also determined through analysis.Finally,a micro-mechanical model of knitted fabric is proposed.This work paves the way for the simulations of buckling modes of a knitted fabric sheet as are observed in experiments.
文摘Based on uniaxial experimental data of a nickel-based superalloy Udimet 720Li under monotonic tension, symmetrically cyclic loading and creep loading, the paper studied to utilize the Bodner-Partom unified constitutive theory to model the mechanical behaviors of the material under these three different loading conditions for the first time. After detailed analysis of the constitutive characteristics of the unified equations, a systematically optimized strategy was proposed to obtain material parameters in the equations. Thereafter, the B-P model was implemented into ABAQUS through UMAT subroutine and was employed to calculate inelastic responses of the material for different uniaxial loading cases at 700℃. Theoretical predictions are compared to experimental data and good agreement is generated.
基金supported by funds from the National Natural Science Foundation of China (Nos. 51374013, 51174005 and 51134012)the Huo Yingdong Funds for Young Teachers to Conduct Researches on Basic Sciences (No. 121050)+1 种基金the academic research activities subsidies for academic and technical leaders and backup candidate in Anhui provincethe funds for the Doctoral Program of Higher Education (No. 20133415110006)
文摘Using the Splitting Hopkinson Pressure Bar (SHPB) experimental system, investigations were made into the dynamic mechanical performances of underground soft rocks. The experiments proved that the measured stress-strain curves display the characteristics of plastic deformation. By making use of a revised overstress constitutive formula for the stress model and by taking into account that the strain rate and strain are a function of I - E(t)/Eo, a revised overstress constitutive formula for the stress model was simplified by applying dimensional analysis and consequently, a simplified overstress formula was obtained for the stress model. Then, by taking into consideration the effects of damage under a dynamic load on the dynamic loading strength of the rock, the continuous damage theory and the statistical strength theory were introduced into the development of the simplified overstress constitutive formula for the stress model. Hence, a damage-based constitutive formula for an overstress model, which can be appropriately applied to the analysis of full dynamic stress-strain curves, was developed. By using the simplified damage-based constitutive formula for an overstress model, the actually measured curves are fitted, indicating that the fitting curves and those actually measured are in good agreement.
文摘Based on the non-equilibrium thermodynamic theory, a new thermo-viscoelastic constitutive model for an incompressible material is proposed. This model can be considered as a kind of generalization of the non-Gaussian network theory in rubber elasticity to include the viscous and the thermal effects. A set of second rank tensorial internal variables was introduced, and in order to adequately describe the evolution of these internal variables, a new expression of the Helmholtz free energy was suggested. The mechanical behavior of the thermo-viscoelastic material under simple shear deformation was studied, and the “viscous dissipation induced” anisotropy due to the change of orientation distribution of molecular chains was examined. Influences of strain rate and thermal softening produced by the viscous dissipation on the shear stress were also discussed. Finally, the model predictions were compared with the experimental results performed by G'Sell et al., thus the validity of the proposed model is verified.
文摘This paper presents ordered rate nonlinear constitutive theories for thermoviscoelastic fluids based on Classical Continuum Mechanics (CCM). We refer to these fluids as classical thermoviscoelastic polymeric fluids. The conservation and balance laws of CCM constitute the core of the mathematical model. Constitutive theories for the Cauchy stress tensor are derived using the conjugate pair in the entropy inequality, additional desired physics, and the representation theorem. The constitutive theories for the Cauchy stress tensor consider convected time derivatives of Green’s strain tensor or the Almansi strain tensor up to order n and the convected time derivatives of the Cauchy stress tensor up to order m. The resulting constitutive theories of order (m, n) are based on integrity and are valid for dilute as well as dense polymeric, compressible, and incompressible fluids with variable material coefficients. It is shown that Maxwell, Oldroyd-B, and Giesekus constitutive models can be described by a single constitutive theory. It is well established that the currently used Maxwell and Oldroyd-B models predict zero normal stress perpendicular to the flow direction. It is shown that this deficiency is a consequence of not retaining certain generators and invariants from the integrity (complete basis) in the constitutive theory and can be corrected by including additional generators and invariants in the constitutive theory. Similar improvements are also suggested for the Giesekus constitutive model. Model problem studies are presented for BVPs consisting of fully developed flow between parallel plates and lid-driven cavities utilizing the new constitutive theories for Maxwell, Oldroyd-B, and Giesekus fluids. Results are compared with those obtained from using currently used constitutive theories for the three polymeric fluids.
文摘In recent papers, Surana et al. presented internal polar non-classical Continuum theory in which velocity gradient tensor in its entirety was incorporated in the conservation and balance laws. Thus, this theory incorporated symmetric part of the velocity gradient tensor (as done in classical theories) as well as skew symmetric part representing varying internal rotation rates between material points which when resisted by deforming continua result in dissipation (and/or storage) of mechanical work. This physics referred as internal polar physics is neglected in classical continuum theories but can be quite significant for some materials. In another recent paper Surana et al. presented ordered rate constitutive theories for internal polar non-classical fluent continua without memory derived using deviatoric Cauchy stress tensor and conjugate strain rate tensors of up to orders n and Cauchy moment tensor and its conjugate symmetric part of the first convected derivative of the rotation gradient tensor. In this constitutive theory higher order convected derivatives of the symmetric part of the rotation gradient tensor are assumed not to contribute to dissipation. Secondly, the skew symmetric part of the velocity gradient tensor is used as rotation rates to determine rate of rotation gradient tensor. This is an approximation to true convected time derivatives of the rotation gradient tensor. The resulting constitutive theory: (1) is incomplete as it neglects the second and higher order convected time derivatives of the symmetric part of the rotation gradient tensor;(2) first convected derivative of the symmetric part of the rotation gradient tensor as used by Surana et al. is only approximate;(3) has inconsistent treatment of dissipation due to Cauchy moment tensor when compared with the dissipation mechanism due to deviatoric part of symmetric Cauchy stress tensor in which convected time derivatives of up to order n are considered in the theory. The purpose of this paper is to present ordered rate constitutive theories for deviatoric Cauchy strain tensor, moment tensor and heat vector for thermofluids without memory in which convected time derivatives of strain tensors up to order n are conjugate with the Cauchy stress tensor and the convected time derivatives of the symmetric part of the rotation gradient tensor up to orders 1n are conjugate with the moment tensor. Conservation and balance laws are used to determine the choice of dependent variables in the constitutive theories: Helmholtz free energy density Φ, entropy density η, Cauchy stress tensor, moment tensor and heat vector. Stress tensor is decomposed into symmetric and skew symmetric parts and the symmetric part of the stress tensor and the moment tensor are further decomposed into equilibrium and deviatoric tensors. It is established through conjugate pairs in entropy inequality that the constitutive theories only need to be derived for symmetric stress tensor, moment tensor and heat vector. Density in the current configuration, convected time derivatives of the strain tensor up to order n, convected time derivatives of the symmetric part of the rotation gradient tensor up to orders 1n, temperature gradient tensor and temperature are considered as argument tensors of all dependent variables in the constitutive theories based on entropy inequality and principle of equipresence. The constitutive theories are derived in contravariant and covariant bases as well as using Jaumann rates. The nth and 1nth order rate constitutive theories for internal polar non-classical thermofluids without memory are specialized for n = 1 and 1n = 1 to demonstrate fundamental differences in the constitutive theories presented here and those used presently for classical thermofluids without memory and those published by Surana et al. for internal polar non-classical incompressible thermofluids.
文摘Objective: To observe the clinical efficacy of acupuncture plus bloodletting therapy in treating insomnia in people with blood stasis constitution. Methods: Seventy-two patients were randomized into a treatment group and a control group by using the random number table, 36 cases each. The treatment group received acupuncture plus bloodletting therapy, while the control group was intervened by oral administration of estazolam. One-week treatment was taken as a course, for 3 successive courses in total. A follow-up study was conducted 3 months later. The Pittsburgh sleep quality index (PSQI) was evaluated before and after the intervention, as well as in the follow-up. The clinical efficacies were also compared. Results: The total effective rate was 88.9% in the treatment group versus 83.3% in the control group, and the between-group difference was statistically significant (P〈0.O5). After the intervention, the PSO.I scores dropped significantly in both groups (both P〈0.05); the between-group difference in PSQI score was statistically significant (P〈O.05). The follow-up study showed that the between-group difference in the global score of PSO, I was statistically significant (P〈0.05). Conclusion: Acupuncture plus bloodletting therapy can produce a more significant efficacy than oral administration of estazolam in treating insomnia in people with blood stasis constitution.
基金Supported by the Applied Basic Research Foundation of Yunnan Province(202101AY070001-050,2019FE001(-026))the Open Foundation(2019KF003)of State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan,Yunnan University+1 种基金the National Natural Science Foundation of China(81860255,81760869)the Scientific Research Foundation of Yunnan Provincial Department of Education(2018JS159)。
文摘OBJECTIVE:Yang-deficiency constitution(YADC)is a common unbalanced constitution that predisposes individuals to certain diseases.However,not all people with YADC manifest develop diseases.This calls for delineation of the underlying molecular mechanisms.Previous studies suggested that the gut microbiota and gene differential expression should be considered.METHODS:In the present study,we compared profiles of gut microbiota between four healthy YADC individuals and those of five healthy balanced constitution(BC)counterparts,based on 16 S r RNA gene sequence analysis.Furthermore,YADC relevant genes identified by comparing 62 healthy YADC and 58 healthy BC individuals in total to perform intersection analysis,functional clustering and pathway enrichment analyses.RESULTS:The levels of harmful gut microbiota(Prevotellaceae,LDA score>4.0,P=0.0141)and beneficial gut microbiota(Ruminococcaceae,LDA score>4.0,P=0.0025,Faecalibacterium,LDA score>4.0,P=0.0484)were both elevated in healthy YADC individuals.Also,we found that the specific metabolic pathway with 2,6-Dichloro-p-hydroquinone 1,2-Dioxygenase(Pcp A)as the core in gut microbiota and the glutathione transferase activity has been enriched by YADC relevant genes in healthy YADC individuals were both responsible for the detoxification of halogenated aromatic hydrocarbon substances.CONCLUSIONS:Both beneficial and harmful factors had been detected in healthy YADC individuals,functionally,they may have triggered homeostasis to maintain the health of individuals with YADC.The homeostasis may be maintained by beneficial and harmful factors from gut flora and genes.Future studies are expected to focus on halogenated aromatic hydrocarbons and their detoxification processes.
文摘For the Reynolds-stress closures in turbulence modelling, a constitutive theory is developed based on the principle of frame indifference and the theory of invariants. The present study sheds light on existing closure models and is instructive to developing new closure relations.
文摘Micromorphic theory(MMT)envisions a material body as a continuous collection of deformable particles;each possesses finite size and inner structure.It is considered as the most successful top-down formulation of a two-level continuum model,in which the deformation is expressed as a sum of macroscopic continuous deformation and internal microscopic deformation of the inner structure.In this work,the kinematics including the objective Eringen tensors is introduced.Balance laws are derived by requiring the energy equation to be form-invariant under the generalized Galilean transformation.The concept of material force and the balance law of pseudomomentum are generalized for MMT.An axiomatic approach is demonstrated in the formulation of constitutive equations for a generalized micromorphic thermoviscoelastic solid,generalized micromorphic fluid,micromorphic plasticity,and micromorphic electromagnetic-thermoelastic solid.Applications of MMT in micro/nanoscale are discussed.
文摘Objective: To observe the effect of acupuncture for children with attention deficit hyperactivity disorder (ADHD). Methods: A total of 36 cases were recruited in this study. Before treatment, a Chinese medical constitution survey was conducted on these children. Based on the survey findings, the children were divided in different groups for acupuncture intervention. Additionally, the heart rate variability and attention were detected respectively before treatment, in the 12th and 24th week after treatment. Results: ADHD kids commonly manifest as a body constitution of yang predominance and heat exuberance. The kids' Body Mass Indexes (BMI) are moderately correlated with attention deficit disorder (ADD). After the treatment of 24 weeks, the ADHD scores were reduced from (10.94±1.98) to (8.56±2.48), showing a statistical significance (P〈0.05); in addition, the low frequency/high frequency (LF/HF) and normalized low frequency (nLF) between the two groups were also statistically different (P〈0.05). Conclusion: Most ADHD kids present with a body constitution of yang predominance and heat exuberance. A well-controlled BMI is helpful for ADHD treatment. Acupuncture can be a supplementary therapy to improve the ADHD symptoms.
基金supported by the National Natural Science Foundation of China(Grant No.11021262)the Fundamental Research Funds for the Central Universities(Grant No.WUT:2013-IV-021)
文摘The elasto-plastic-damage behavior of anisotropic aluminum alloys is investigated under finite deformation using a physical mechanism based constitutive model.With an application to the structural calculation,the present model is used to describe and analyze the mechanical response of anisotropic 6260-T6 aluminum alloy extrusions.For the tensile specimens extracted along three different material orientations from the extruded aluminum profile,twelve simulations are carried out covering four different specimen geometries.The simulation results in force-displacement response and central logarithmic axial strain evolution are compared with experimental results.From the comparisons,it can be concluded that the present model has the capacity to describe the behavior of anisotropic material.From the force-displacement curves,the anisotropy is observed in different material orientations,and the physical mechanism of anisotropy is analyzed.