企业技术创新视阈下价值链结构粘性研究

向价值链高端升级是各国经济发展的重要内容,但拉美、东南亚等国价值链升级并不成功。价值链升级的本质是价值链不同层级企业主体身份的转变,实现这一转换依赖特定条件也存在诸多阻力。对价值链各主体企业特质进行研究发现价值链结构存在粘性。导致价值链粘性的主要原因是后发企业创新机会窗口丧失、全球价值链领先企业的封闭性策略行为及价值链纵向知识溢出较低。为促进我国产业发展需通过建立与跨国公司直接竞争的价值链以促进价值链横向知识溢出,并及时进入新兴产业以充分利用创新机会窗口。

全要素生产率冲击与制造业行业新质生产力——基于结构粘性视角的分析

新质生产力的核心标志是全要素生产率的大幅度提升。基于中国A股制造业企业数据识别宏观层面、行业层面的全要素生产率系统性冲击,通过反事实结构模拟,利用信息熵和行业关联度评估制造业行业对全要素生产率冲击的结构粘性,将其作为行业新质生产力指标。研究发现,计算机、通信电子设备制造业,专用设备和通用设备制造业具有较强的新质生产力;电气机械及器材制造业和黑色金属冶炼及压延加工业的新质生产力呈现出结构分化的特征,下尾部企业对全要素生产率冲击不敏感;对于新质生产力较弱的行业,如有色金属冶炼及压延加工业和非金属矿物制品业等,需要强有力的外生激励。此外,信息熵与行业关联度之间呈现较强的正相关关系,表明高新质生产力水平行业具有辐射带动作用。研究结论为评估行业新质生产力提供了方法参考,也有助于为差异化行业激励政策的实施提供理论依据。

我国经济结构粘性及其调整

多年来,学者从不同角度研究经济结构变动特征,调整经济结构是后危机时期诸多国家采取促进经济长期发展的策略。运用结构调整的数理模型,系统分析了2004-2012年中国宏、微经济数据,比较了我国2008年前后经济结构调整特征。结果表明,我国经济结构调整过程中存在结构粘性的现象。经济结构粘性存在的主要原因是危机后我国稳增长的政策诱发的。因此,化解经济结构粘性的主要措施是,转变政府主导的市场经济模式,理顺保增长与调结构的关系,在某些领域可以采取激进式的结构性改革。

MATLAB在识别粘性土微观孔隙结构中的应用

MATLAB是一款功能强大的数字图像处理软件。本文分析了MATALB用于数字图像处理的主要优点,提出了MATLAB识别土体微观结构图像的基本思路,运用MATLAB识别了某粘性土微观结构图像的孔隙结构信息。研究表明:MATLAB可以通过灰度图像转换、阈值优选和二值化处理可以有效识别土体微观孔隙结构信息,具有良好的应用效果。

基于Van Leer+AUSM混合格式求解三维N-S方程

基于多块粘性结构网格,开展了三维N-S方程数值算法的研究。控制方程的空间离散采用有限体积法,在前人工作的基础上,发展了Van Leer+AUSM混合格式并应用到对流通量的离散中,粘性项采用中心格式离散并利用格林定理计算粘性通量中的导数项,时间推进采用五步R-K法,湍流模型为S-A一方程模型。最后,以M6机翼和某超声速弹丸的粘性流场作为数值算例,计算表明:发展的数值算法对跨声速、超声速流场均具有较高的分辨率,适用于跨、超声速流场的数值模拟。

功能互补、零售终端与联盟(连锁)集团(FRR)范式——以中小生产性组织为例

基于市场结构与商品消费结构特点,中小生产商、零售商从关联性功能互补商品特征角度,通过商品零售终端进行战略联盟和商品组合,产生的相互贡献形成的稳定协同"粘性"结构,可以引导中小生产商、零售商通过零售终端战略联盟(连锁)集团组织(FRR)范式参与市场竞争。该范式不仅为资源互补型经济组织的战略联盟提供了理论依据,而且对调节目前市场结构,促进市场经济发展具有较为积极意义。

无粘结预应力混凝土楼板轴向预应力效应计算分析

根据变形协调原理 ,建立了考虑支座约束影响的无粘结预应力楼板轴向预应力效应计算公式 ,提出的计算方法与概念 ,对于无粘结预应力楼盖设计具有一定参考价值。

Ethylene Polymerization with Palygorskite Supported Nickel-Diimine Catalyst

A nickel-diimine catalyst [N, N'-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1, 3-butadiene nickel dibromide, DMN] was supported on palygorskite clay for ethylene slurry polymerization. The effect of supporting methods on the catalyst impregnation was studied and compared. Pretreatment of the support with methylalumi-noxane (MAO) followed by DMN impregnation gave higher catalyst loading and catalytic activity than the direct impregnation of DMN. Catalyst activity as high as 5.42×105g PE·molNi-1·h-1 was achieved at ethylene pressure of 6.87×105 Pa and polymerization temperature of 20℃. In particular, the morphological change of the support during MAO treatment was characterized and analyzed. It was found that nano-fiber clusters formed during the support pretreatment, which increased the surface area of the support and favored the impregnation of the catalyst. The investigation of polymerization behavior of supported catalyst revealed that the polymerization rate could be kept at a relatively high level for a long time, different from the homogeneous catalyst. By analyzing the SEM photographs of the polymer produced by the supported catalyst, the morphological evolution of polymer particles was preliminarily studied.

Effects of Colloidal Silica Binder on Catalytic Activity and Adhesion of HZSM-5 Coatings for Structured Reactors

HZSM-5 coating using three colloidal silica binders, acidic colloidal silica （ACS）, neutral colloidal silica （NCS） and basic colloidal silica （BCS）, was prepared to study the effect of hinders on their adhesion and catalytic activity. Scanning electron microscopy characterization indicated that the zeolite coating using BCS shows the smoothest surface with higher homogeneity and adherence strength. The specific surface area, relative crystallization and acid site strength of zeolites are also dependent on the binder used. Catalytic cracking of supercritical n- dodecane over the series of zeolite coating with various binders indicated that HZSM-5 coating with BCS exhibits the highest and the most stable catalytic activity compared with other kinds of binders, and also exhibits a stable catalytic activity ascribed to its proper acid property and microstructure.

Characteristics of viscous debris flow in a drainage channel with an energy dissipation structure

A new type of drainage channel with an energy dissipation structure has been proposed based on previous engineering experiences and practical requirements for hazard mitigation in earthquakeaffected areas.Experimental studies were performed to determine the characteristics of viscous debris flow in a drainage channel of this type with a slope of 15%.The velocity and depth of the viscous debris flow were measured,processed,and subsequently used to characterize the viscous debris flow in the drainage channel.Observations of this experiment showed that the surface of the viscous debris flow in a smooth drainage channel was smoother than that of a similar debris flow passing through the energy dissipation section in a channel of the new type studied here.However,the flow patterns in the two types of channels were similar at other points.These experimental results show that the depth of the viscous debris flow downstream of the energy dissipation structure increased gradually with the length of the energy dissipation structure.In addition,in the smooth channel,the viscous debris-flow velocity downstream of the energy dissipation structure decreased gradually with the length of the energy dissipation structure.Furthermore,theviscous debris-flow depth and velocity were slightly affected by variations in the width of the energy dissipation structure when the channel slope was 15%.Finally,the energy dissipation ratio increased gradually as the length and width of the energy dissipation structure increased;the maximum energy dissipation ratio observed was 62.9%(where B = 0.6m and L/w = 6.0).

The Flow Behavior of Poly(m-Phenyleneisophthalamide) Concentrated Solution

By means of HAAKE RS105L cone and plate rheometer the concentrated solution, including viscous flow activation energy, non-Newtonian index, structural viscosity index and relaxation time of the PMIA solution were studied. The effect of concentration and temperature of the solution and molecular weight of the polymer on its non-Newtonian behavior was investigated. The results showed that PMIA concentrated solution prepared via low temperature condensation was of non-Newtonian fluid. With the decrease of temperature, increase of solution concentration and PMIA molecular weight, the deviation of the solution from Newtonian behavior decreased. The molecular weight of the polymer and the concentration of the solution affected the non- Newtonian behavior mete intensively.

The role of the symmetry and the flexibility of the anion on the characteristics of the nanostructures and the viscosities of ionic liquids

The transport properties of ionic liquids(ILs) are crucial properties in view of their applications in electrochemical devices. One of the most important advantages of ILs is that their chemical–physical properties and consequently their bulk performances can be well tuned by optimizing the chemical structures of their ions. This will require elucidating the structural features of the ions that fundamentally determine the characteristics of the nanostructures and the viscosities of ILs. Here we showed for the first time that the "rigidity", the order,and the compactness of the three-dimensional ionic networks generated by the anions and the cation head groups determine the formation and the sizes of the nanostructures in the apolar domains of ILs. We also found that the properties of ionic networks are governed by the conformational flexibility and the symmetry of the anion and/or the cation head group. The thermal stability of the nanostructures of ILs was shown to be controlled by the sensitivity of the conformational equilibrium of the anion to the change of temperature. We showed that the viscosity of ILs is strongly related to the symmetry and the flexibility of the constitute ions rather than to the size of the nanostructures of ILs. Therefore, the characteristics of the nanostructures and the viscosities of ILs, especially the thermal stability of the nanostructures, can be fine-tuned by tailoring the symmetry and the conformational flexibility of the anion.

First principles calculation on electronic structure,chemical bonding,elastic and optical properties of novel tungsten triboride

The electronic structures,chemical bonding,elastic and optical properties of the novel hP24 phase WB3 were investigated by using density-functional theory(DFT) within generalized gradient approximation(GGA).The calculated energy band structures show that the hP24 phase WB3 is metallic material.The density of state(DOS) and the partial density of state(PDOS) calculations show that the DOS near the Fermi level is mainly from the W 5d and B 2p states.Population analysis suggests that the chemical bonding in hP24-WB3 has predominantly covalent characteristics with mixed covalent-ionic characteristics.Basic physical properties,such as lattice constant,bulk modulus,shear modulus and elastic constants Cij were calculated.The elastic modulus E and Poisson ratio υ were also predicted.The results show that hP24-WB3 phase is mechanically stable and behaves in a brittle manner.Detailed analysis of all optical functions reveals that WB3 is a better dielectric material,and reflectivity spectra show that WB3 can be promised as good coating material in the energy regions of 8.5-11.4 eV and 14.5-15.5 eV.

DRUCKER-PRAGER YIELD CRITERIA IN VISCOELASTIC-PLASTIC CONSTITUTIVE MODEL FOR THE STUDY OF SEA ICE DYNAMICS

Based on the characteristics of sea ice drifting and ridging at meso-small scale, the Drucker-Prager （D-P） yield criteria was introduced into the Viscoelastic-Plastic （VEP） constitutive model for the study of sea ice dynamics. In this model, the Kelvin-Vogit viscoelastic model was adopted in the elastic stage, and the associated normal flow rule was used in the plastic stage. Using the VEP model, the sea ice ridging process was simulated in an idealized rectangular basin, and the simulation results show that the simulated ice ridge thickness is consistent with the analytical solution. Moreover, the VEP model with the D-P yield criteria was also applied for the sea ice simulation of Bohai Sea, and the ice thickness, concentration, velocity, and ice stress were obtained in 48 h. The simulated thickness distributions agree well with the satellite images. The singular problem in the Mohr^7oulomb （M-C） yield criteria was overcome by the D-P yield criteria, and the computational efficiency was also improved. In the numerical simulations described above, the smoothed particle hydrodynamics was applied.

An elastic-viscous-plastic model for overconsolidated clays

The influences of time on clays are discussed first,and the concept of the instant normal compression line is proposed by analyzing the existing theories and experimental results.Based on the creep law,the relationship between the aging time and the overconsolidation parameter is built.With the reloading equation of the UH model(unified hardening model for overconsolidated clays) used to calculate the instant compression deformation,a one-dimensional stress-strain-time relationship is proposed.Furthermore,the evolution of this relationship is analyzed,and the characteristic rate that is a function of the overconsolidation parameter is defined.Then a three-dimensional elastic-viscous-plastic constitutive model is suggested by incorporating equivalent time into the current yield function of the UH model.The new model can describe not only creep,rate effect and other viscous phenomena,but also shear dilatancy,strain softening and other behaviors of overconsolidated clays.Besides,compared with the modified Cam-clay model it requires only one additional parameter(the coefficient of secondary compression) to consider the creep law.Finally,because the proposed model can be changed into the UH model under instantaneous loading,the elastic-plastic and elastic-viscous-plastic frameworks are unified.

Molecular dynamics study on the relationships of modeling,structural and energy properties with sensitivity for RDX-based PBXs

In this paper,a primary model is established for MD(molecular dynamics) simulation for the PBXs(polymer-bonded explosives) with RDX(cyclotrimethylene trinitramine) as base explosive and PS as polymer binder.A series of results from the MD simulation are compared between two PBX models,which are represented by PBX1 and PBX2,respectively,including one PS molecular chain having 46 repeating units and two PS molecular chains with each having 23 repeating units.It has been found that their structural,interaction energy and mechanical properties are basically consistent between the two models.A systematic MD study for the PBX2 is performed under NPT conditions at five different temperatures,i.e.,195 K,245 K,295 K,345 K,and 395 K.We have found that with the temperature increase,the maximum bond length(L max) of RDX N N trigger bond increases,and the interaction energy(E N-N) between two N atoms of the N-N trigger bond and the cohesive energy density(CED) decrease.These phenomena agree with the experimental fact that the PBX becomes more sensitive as the temperature increases.Therefore,we propose to use the maximum bond length L max of the trigger bond of the easily decomposed and exploded component and the interaction energy E N-N of the two relevant atoms as theoretical criteria to judge or predict the relative degree of heat and impact sensitivity for the energetic composites such as PBXs and solid propellants.

Effects of nanoclay addition on the permeability and mechanical properties of ultra high toughness cementitious composites

Tuning microstructures by adding nanoparticles is a promising way of improving the performance of cementitious composites.In this study,nanoclay was introduced to polyvinyl alcohol(PVA)fiber reinforced ultra high toughness cementitious composites(UHTCCs).The mechanical properties,crack patterns,water permeation resistance,and microstructures of UHTCCs with different dosages of nanoclay were studied.The addition of a proper dosage of nanoclay shows few effects on the compressive strength of UHTCCs,however,the compressive strength is decreased when an excessive amount of nanoclay is added.The flexural deformation capacity of UHTCCs is independent of nanoclay dosage,whereas the flexural strength generally decreases with an increasing dosage of nanoclay.Different cracking patterns were observed in the ultra high toughness cementitious composites containing nanoclay(NC-UHTCC)specimens subject to bending tests.A UHTCC with 1%(in weight)nanoclay shows the best water permeation resistance and the lowest water permeability.Variations in the mechanical properties and the water permeation resistance of UHTCCs containing different dosages of nanoclay could be ascribed to the synthetic effects of filling and heterogeneous nucleation of nanoclay at low dosages and the agglomeration effect of nanoclay at high dosages.This study is to optimize the water permeation resistance of UHTCCs,paving a path for the future application of UHTCCs in the fields of construction,decoration,and repair.

The interfacial fracture behavior of foam core composite sandwich structures by a viscoelastic cohesive model

A sandwich beam model consisting of two face sheets and a foam core bonded by a viscoelastic adhesive layer is considered in order to investigate interfacial fracture behavior. Firstly, a cohesive zone model in conjunction with a Maxwell element in parallel, or with a Kelvin element in series, respectively, is employed to describe the characteristics of viscoelasticity for the adhesive layer. The models can be implemented into the implicit finite element code. Next, the parametric study shows that the in- fluences of loading rates on the cohesive zone energy and strength are quite different for different models. Finally, a sandwich double cantilever beam model is adopted to simulate the interface crack growth between the face sheet and core. Numerical examples are presented for various loading rates to demonstrate the efficacy of the rate-dependent cohesive models.

Theoretical studies on the complexation of Eu(Ⅲ) and Am(Ⅲ) with HDEHP： structure, bonding nature and stability

Separation of trivalent lanthanides （Ln（Ⅲ）） and actinides （An（Ⅲ）） is a key issue in the advanced spent nuclear fuel repro- cessing. In the well-known trivalent actinide lanthanide separation by phosphorus reagent extraction from aqueous komplexes （TALSPEAK） process, the organophosphorus ligand HDEHP （di-（2-ethylhexyl） phosphoric acid） has been used as an efficient reagent for the partitioning of Ln（Ⅲ） from An（Ⅲ） with the combination of a holdback reagent in aqueous lactate buffer solu- tion. In this work, the structural and electronic properties of Eu3＋ and Am3＋ complexes with HDEHP in nitric acid solution have been systematically explored by using scalar-relativistic density functional theory （DFT）. It was found that HDEHP can coordinate with M（Ⅲ） （M=Eu, Am） cations in the form of hydrogen-bonded dimers HL2 （L=DEHP）, and the metal ions pre- fer to coordinate with the phosphoryl oxygen atom of the ligand. For all the extraction complexes, the metal-ligand bonds are mainly ionic in nature. Although Eu（Ⅲ） complexes have higher interaction energies, the HL2- dimer shows comparable affini- ty for Eu（Ⅲ） and Am（Ⅲ） according to thermodynamic analysis, nonahydrate. It is expected that this work could provide insightful HDEHP at the molecular level. which may be attributed to the higher stabilities of Eu（Ⅲ） information on the complexation of An（Ⅲ） and Ln（Ⅲ） with

Structure and property of metal melt Ⅳ——Evolution of titanium melt residual bond structure and its effect on dynamic viscosity

Based on the concept of melt residual bonds, a calculating model quantitatively describing the evolution of the residual bond structure of titanium melt at the melting point or in a certain range above the melting point was established; i.e., both the size ds and the bond number n of the residual bond structure decrease monotonously with the increase of temperature. By mathe- matical deduction, a linear relationship between the residual bond structure size ds and the dynamic viscosity 17 of Titanium melt was revealed, i.e., η= 0.876 ＋ 0.471·ds, which is of great significance to the investigation of the relationship between the melt microstructure and the macroscopic properties of metals with high melting temperature.