A constitutive model of quasi-Newtonian fluid based on the type of flow is used in abrupt planar contraction now.The numerical results from finite element analysis are consistent with experimental data for stress patt...A constitutive model of quasi-Newtonian fluid based on the type of flow is used in abrupt planar contraction now.The numerical results from finite element analysis are consistent with experimental data for stress patterns and velocityprofiles in the flow field. The chain conformations of polymer melts are then investigated in such a planar contraction byusing the phenomenological model with internal parameters proposed by the author. That is, the shape and orientation ofpolymer chain coils are predicted and discussed in different flow regions of the contraction flow field that possess simpleshear flow, extensional flow, vortical flow, and mixed flow respectively.展开更多
Firstly,I point out the problems in the fruit supply chain management.Then through field survey,we know that busywork flow plays a very important role in the fruit supply chain management.I establish the mathematical ...Firstly,I point out the problems in the fruit supply chain management.Then through field survey,we know that busywork flow plays a very important role in the fruit supply chain management.I establish the mathematical model,to derive that the supply chain management of corporate procurement and supply network is the optimal economic model.In terms of the performance of supply chain,I draw the following conclusions:(i) Busywork flow can achieve the supply chain management,and reduces logistics costs in the whole process of circulation;(ii) Busywork flow can improve logistics services for the customers and reduces coordination costs;(iii) The establishment of modern information system can reduce logistics costs;(iv) Busywork flow can improve distribution efficiency and reduce costs;(v) Busywork flow can reduce and avoid the costs of return of goods;(vi) The operation of the busywork flow can achieve integrated transport and business outsourcing to third-party logistics,thereby reducing costs,reducing transport links,reasonably choosing the means of transport,formulating the optimal transportation plan,improving the mode of transport,and increasing the cargo loading amount.(vii) Busywork flow promotes the use of e-commerce.I also express my own views on upgrade version of corporate procurement and supply network.Finally I point out some problems in the existing corporate procurement and supply network,and put forward the following recommendations:developing township-level 4S fruit shop according to the business development,with the functions of purchasing apple,supplying means of agricultural production,providing technical services and developing market;building " corporate ecological orchard" through holding.展开更多
An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the de...An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the dependence of ηo and τt on M3.4 were derived from the theory of non-linear viscoelasticity with constraints of entanglements for polymer melts and substituted into the Oldroye-Walters-Fredickson constitutive equation. An integral constitutive equation for polymer melts was consequently obtained. Some material functions of the constitutive equation related to certain 'test flow' are examined as follows : (1) simple steady shear flow; (2) steady elongation flow; (3) small-amplitude oscillatory shear flow; (4) stress growth upon the inception of steady shear elongation flow; (5) stress relaxation (modulus and compllance). These theoretical relations for simple steady shear flow were compared with experimental data from our laboratory and references for various polymer melts and concentrated solutions. A good agreement between the theory and experiment was achieved.展开更多
Polymer chain coils with entanglement is a crucial scale of structures in polymer materials since their relaxationtimes are matching practical processing times.Based on the phenomenological model of polymer chain coil...Polymer chain coils with entanglement is a crucial scale of structures in polymer materials since their relaxationtimes are matching practical processing times.Based on the phenomenological model of polymer chain coils and a new finiteelement approach,we have designed a computer software including solver,pre-and post-processing modules,and developeda digital analysis technology for the morphology of polymer chain coils in flow fields(DAMPC).Using this technology wemay simulate the morphology development of chain coils in various flow fields,such as simple shear flow,elongational flow,and any complex flow at transient or steady state.The applications made up to now show that the software predictions arecomparable with experimental results.展开更多
The efficiencies of 6 kinds of macromolecules with dendritic structure in improving the flow properties of crude oil were investigated. The dendritic additives were synthesized using low-generation dendritic poly(amid...The efficiencies of 6 kinds of macromolecules with dendritic structure in improving the flow properties of crude oil were investigated. The dendritic additives were synthesized using low-generation dendritic poly(amidoamine) and alkyl longchain acrylic esters as starting materials, and their structures were characterized by the Fourier transform infrared spectroscopy, 1H-nuclear magnetic resonance and elemental analysis. The effects on the pour point and rheological properties of crude oil samples were studied. Efficiencies of dendritic long-chain esters were not only influenced by the alky chain length, but also by the generation of dendrimer. The longer the alkyl chain of dendritic long-chain ester was, the better the effect in the reduction of pour point and apparent viscosity was. Efficiencies of 1.5 generation dendritic long-chain ester with 8 branched chains for the reduction of pour point and apparent viscosity were superior to those of 0.5 generation dendritic long-chain ester with 4 branched chains. Under the same conditions, efficiencies of 1.5 generation dendritic eighteen ester were superior to those of other 1.5 generation dendritic long-chain esters for the reduction of pour point and viscosity of crude oil.展开更多
During B-cell development and maturation,the antigen receptor,which is encoded by the immunoglobulin heavy-(IgH) and light-chain genes,rearrange to associate one of a number of variable,diverse,and joining gene segmen...During B-cell development and maturation,the antigen receptor,which is encoded by the immunoglobulin heavy-(IgH) and light-chain genes,rearrange to associate one of a number of variable,diverse,and joining gene segments.A single mature B-cell expresses an IgH chain and either a kappa or lambda light chain,which is known as allelic or isotypic exclusion.In normal or reactive conditions,lymphoid cells comprise the mixtures of lymphocytes with either kappa or lambda expression.展开更多
基金This work was supported by the research grants from the National Nature Science Foundation of China (No. 20174024) and the Special Founds for Major State Basic Research Projects (G199906408)
文摘A constitutive model of quasi-Newtonian fluid based on the type of flow is used in abrupt planar contraction now.The numerical results from finite element analysis are consistent with experimental data for stress patterns and velocityprofiles in the flow field. The chain conformations of polymer melts are then investigated in such a planar contraction byusing the phenomenological model with internal parameters proposed by the author. That is, the shape and orientation ofpolymer chain coils are predicted and discussed in different flow regions of the contraction flow field that possess simpleshear flow, extensional flow, vortical flow, and mixed flow respectively.
文摘Firstly,I point out the problems in the fruit supply chain management.Then through field survey,we know that busywork flow plays a very important role in the fruit supply chain management.I establish the mathematical model,to derive that the supply chain management of corporate procurement and supply network is the optimal economic model.In terms of the performance of supply chain,I draw the following conclusions:(i) Busywork flow can achieve the supply chain management,and reduces logistics costs in the whole process of circulation;(ii) Busywork flow can improve logistics services for the customers and reduces coordination costs;(iii) The establishment of modern information system can reduce logistics costs;(iv) Busywork flow can improve distribution efficiency and reduce costs;(v) Busywork flow can reduce and avoid the costs of return of goods;(vi) The operation of the busywork flow can achieve integrated transport and business outsourcing to third-party logistics,thereby reducing costs,reducing transport links,reasonably choosing the means of transport,formulating the optimal transportation plan,improving the mode of transport,and increasing the cargo loading amount.(vii) Busywork flow promotes the use of e-commerce.I also express my own views on upgrade version of corporate procurement and supply network.Finally I point out some problems in the existing corporate procurement and supply network,and put forward the following recommendations:developing township-level 4S fruit shop according to the business development,with the functions of purchasing apple,supplying means of agricultural production,providing technical services and developing market;building " corporate ecological orchard" through holding.
文摘An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the dependence of ηo and τt on M3.4 were derived from the theory of non-linear viscoelasticity with constraints of entanglements for polymer melts and substituted into the Oldroye-Walters-Fredickson constitutive equation. An integral constitutive equation for polymer melts was consequently obtained. Some material functions of the constitutive equation related to certain 'test flow' are examined as follows : (1) simple steady shear flow; (2) steady elongation flow; (3) small-amplitude oscillatory shear flow; (4) stress growth upon the inception of steady shear elongation flow; (5) stress relaxation (modulus and compllance). These theoretical relations for simple steady shear flow were compared with experimental data from our laboratory and references for various polymer melts and concentrated solutions. A good agreement between the theory and experiment was achieved.
基金This work was supported by the research grants from the National Natural Science Foundation of China(No.50290090No.20204007+2 种基金No.20174024)National 863 project of China(No.2002AA336120)the Doctoral Foundation of National Education Committee of China(
文摘Polymer chain coils with entanglement is a crucial scale of structures in polymer materials since their relaxationtimes are matching practical processing times.Based on the phenomenological model of polymer chain coils and a new finiteelement approach,we have designed a computer software including solver,pre-and post-processing modules,and developeda digital analysis technology for the morphology of polymer chain coils in flow fields(DAMPC).Using this technology wemay simulate the morphology development of chain coils in various flow fields,such as simple shear flow,elongational flow,and any complex flow at transient or steady state.The applications made up to now show that the software predictions arecomparable with experimental results.
基金supported financially by the Heilongjiang Postdoctorial Financial Foundation of China (Project NO. LBH-Zo8290)The Daqing Oil Field of China was thanked for providing the financial support and the crude oil
文摘The efficiencies of 6 kinds of macromolecules with dendritic structure in improving the flow properties of crude oil were investigated. The dendritic additives were synthesized using low-generation dendritic poly(amidoamine) and alkyl longchain acrylic esters as starting materials, and their structures were characterized by the Fourier transform infrared spectroscopy, 1H-nuclear magnetic resonance and elemental analysis. The effects on the pour point and rheological properties of crude oil samples were studied. Efficiencies of dendritic long-chain esters were not only influenced by the alky chain length, but also by the generation of dendrimer. The longer the alkyl chain of dendritic long-chain ester was, the better the effect in the reduction of pour point and apparent viscosity was. Efficiencies of 1.5 generation dendritic long-chain ester with 8 branched chains for the reduction of pour point and apparent viscosity were superior to those of 0.5 generation dendritic long-chain ester with 4 branched chains. Under the same conditions, efficiencies of 1.5 generation dendritic eighteen ester were superior to those of other 1.5 generation dendritic long-chain esters for the reduction of pour point and viscosity of crude oil.
文摘During B-cell development and maturation,the antigen receptor,which is encoded by the immunoglobulin heavy-(IgH) and light-chain genes,rearrange to associate one of a number of variable,diverse,and joining gene segments.A single mature B-cell expresses an IgH chain and either a kappa or lambda light chain,which is known as allelic or isotypic exclusion.In normal or reactive conditions,lymphoid cells comprise the mixtures of lymphocytes with either kappa or lambda expression.
