THEORETICAL BASIS AND GENERAL OPTIMAL FORMULATIONS OF ISOPARAMETRIC GENERALIZED HYBRID/MIXED ELEMENT MODEL FOR IMPROVED STRESS ANALYSIS

By the modified three-field Hu-Washizu principle, this paper establishes a theoretical founda- tion and general convenient formulations to generate convergent stable generalized hybrid/mixed cle- ment (GH/ME) model which is invariant with respect to coordinate, insensitive to geometric distortion and suitable for improved stress computation. In the two proposed formulations, the stress equilibrium and orthogonality constraints are imposed through incompatible displacement and internal strain modes respectively. The proposed model by the general formulations in this paper is characterized by including as- sumed stress/strain, assumed stress, variable-node, singular, compatible and incompatible GH/ME models. When using regular meshes or the constant values of the isoparametric Jacobian Det in the assumed strain in- terpolation, the incompatible GH/ME model degenerates to the hybrid/mixed element model. Both general and concrete guidelines for the optimal selection of element shape functions are suggested. By means of the GH/ME theory in this paper, a family of new GH/ME can be and have been easily constructed. The software can also be developed conveniently because all the standard subroutines for the corresponding isoparametric displacement elements can be utilized directly.

Discrete formulation of mixed finite element methods for vapor deposition chemical reaction equations

The vapor deposition chemical reaction processes, which are of extremely extensive applications, can be classified as a mathematical model by the following governing nonlinear partial differential equations containing velocity vector, temperature field, pressure field, and gas mass field. The mixed finite element （MFE） method is employed to study the system of equations for the vapor deposition chemical reaction processes. The semidiscrete and fully discrete MFE formulations are derived. And the existence and convergence （error estimate） of the semidiscrete and fully discrete MFE solutions are demonstrated. By employing MFE method to treat the system of equations for the vapor deposition chemical reaction processes, the numerical solutions of the velocity vector, the temperature field, the pressure field, and the gas mass field can be found out simultaneously. Thus, these researches are not only of important theoretical means, but also of extremely extensive applied vistas.

WEAK FORMULATION OF MIXED STATE EQUATION ANDBOUNDARY VALUE PROBLEM OF LAMINATEDCYLINDRICAL SHELL

Weak formulation of mixed state equations including boundary conditions are presented in a cylindrical coordinate system by introducing Hellinger-Reissner variational principle. Analytical solutions are obtained for laminated cylindrical shell by means of state space method. The present study extends and unifies the solution of laminated shells.

A STABILIZED CRANK-NICOLSON MIXED FINITE VOLUME ELEMENT FORMULATION FOR THE NON-STATIONARY PARABOLIZED NAVIER-STOKES EQUATIONS

A time semi-discrete Crank-Nicolson （CN） formulation with second-order time accuracy for the non-stationary parabolized Navier-Stokes equations is firstly established. And then, a fully discrete stabilized CN mixed finite volume element （SCNMFVE） formu- lation based on two local Gaussian integrals and parameter-free with the second-order time accuracy is established directly from the time semi-discrete CN formulation so that it could avoid the discussion for semi-discrete SCNMFVE formulation with respect to spatial wriables and its theoretical analysis becomes very simple. Finally, the error estimates of SCNMFVE solutions are provided.

A STABILIZED MIXED FINITE ELEMENT FORMULATION FOR THE NON-STATIONARY INCOMPRESSIBLE BOUSSINESQ EQUATIONS

In this study, we employ mixed finite element （MFE） method, two local Gauss integrals, and parameter-free to establish a stabilized MFE formulation for the non-stationary incompressible Boussinesq equations. We also provide the theoretical analysis of the existence, uniqueness, stability, and convergence of the stabilized MFE solutions for the stabilized MFE formulation.

Analysis of Inhibitory Effects of Mixed Biogas Slurry-pesticide Formulation against Alternaria solani Sorauer

[Objective] The paper was to explore the inhibitory effect of mixed biogas slurry-pesticide formulation against Alternaria solani Sorauer. [Method] Different concentrations of Triadimefon, Hekang, Yibao, Propamocarb hydrochloride and Jinggangmycin were mixed with biogas slurry, and their inhibitory effects were determined by the methods of mycelial inhibition and spore germination. [Result] Mycelial inhibition study showed that mixed formulation of Propamocarb hydrochloride owned the highest inhibition efficiency, and its EC50 value was 3 mg/L. For spore germination, the inhibitory effects of the tested formulations were almost the same as CK, but Hekang and Jinggangmycin had relatively stronger inhibitory effect. The inhibitory effect of mixed formulations with water as solvent was significant. Five kinds of agro-chemicals mixed with biogas slurry had much stronger inhibition effect against the growth of mycelium than that on spore germination. [Conclusion] This study laid foundations for the development of neo-pesticide.

A MIXED VARIATIONAL FORMULATION FOR LARGE DEFORMATION ANALYSIS OF PLATES

A mixed vuriational formulation for large deformation analysis of plates is introduced. In this formulation the equilibrium ami compatibility equations are satisfied identically by means of stress functions and displacement components, respectively, and the constitu,lye equations are satisfied in a least square sense. An example is solved and the results are compared with those available in the literature.Further, the functional is particularized for buckling analysis of plates and a simple example is solved to illustrate the theory.

A REDUCED MFE FORMULATION BASED ON POD FOR THE NON-STATIONARY CONDUCTION-CONVECTION PROBLEMS

In this article, a reduced mixed finite element （MFE） formulation based on proper orthogonal decomposition （POD） for the non-stationary conduction-convection problems is presented. Also the error estimates between the reduced MFE solutions based on POD and usual MFE solutions are derived. It is shown by numerical examples that the results of numerical computation are consistent with theoretical conclusions. Moreover, it is shown that the reduced MFE formulation based on POD is feasible and efficient in finding numerical solutions for the non-stationary conduction-convection problems.

A REDUCED-ORDER MFE FORMULATION BASED ON POD METHOD FOR PARABOLIC EQUATIONS

In this paper, we extend the applications of proper orthogonal decomposition （POD） method, i.e., apply POD method to a mixed finite element （MFE） formulation naturally satisfied Brezz-Babu^ka for parabolic equations, establish a reduced-order MFE formulation with lower dimensions and sufficiently high accuracy, and provide the error estimates between the reduced-order POD MFE solutions and the classical MFE solutions and the implementation of algorithm for solving reduced-order MFE formulation. Some numerical examples illustrate the fact that the results of numerical computation are consis- tent with theoretical conclusions. Moreover, it is shown that the new reduced-order MFE formulation based on POD method is feasible and efficient for solving MFE formulation for parabolic equations.

Multiscale Hybrid-Mixed Finite Element Method for Flow Simulation in Fractured Porous Media

The multiscale hybrid-mixed(MHM)method is applied to the numerical approximation of two-dimensional matrix fluid flow in porous media with fractures.The two-dimensional fluid flow in the reservoir and the one-dimensional flow in the discrete fractures are approximated using mixed finite elements.The coupling of the two-dimensional matrix flow with the one-dimensional fracture flow is enforced using the pressure of the one-dimensional flow as a Lagrange multiplier to express the conservation of fluid transfer between the fracture flow and the divergence of the one-dimensional fracture flux.A zero-dimensional pressure(point element)is used to express conservation of mass where fractures intersect.The issuing simulation is then reduced using the MHM method leading to accurate results with a very reduced number of global equations.A general system was developed where fracture geometries and conductivities are specified in an input file and meshes are generated using the public domain mesh generator GMsh.Several test cases illustrate the effectiveness of the proposed approach by comparing the multiscale results with direct simulations.

ANALYSIS OF AUGMENTED THREE-FIELD MACRO-HYBRID MIXED FINITE ELEMENT SCHEMES

On the basis of composition duality principles, augmented three-field macrohybrid mixed variational problems and finite element schemes are analyzed. The compatibility condition adopted here, for compositional dualization, is the coupling operator surjectivity, property that expresses in a general operator sense the Ladysenskaja-Babulka-Brezzi inf-sup condition. Variational macro-hybridization is performed under the assumption of decomposable primal and dual spaces relative to nonoverlapping domain decompositions. Then, through compositional dualization macro-hybrid mixed problems are obtained, with internal boundary dual traces as Lagrange multipliers. Also, ＂mass＂ preconditioned aug- mentation of three-field formulations are derived, stabilizing macro-hybrid mixed finite element schemes and rendering possible speed up of rates of convergence. Dual mixed incompressible Darcy flow problems illustrate the theory throughout the paper.

EVOLUTION FILTRATION PROBLEMS WITH SEAWATER INTRUSION: TWO-PHASE FLOW DUAL MIXED VARIATIONAL ANALYSIS

Tow-phase flow mixed variational formulations of evolution filtration problems with seawater intrusion are analyzed. A dual mixed fractional flow velocity-pressure model is considered with an air-fresh water and a fresh water-seawater characterization. For analysis and computational purposes, spatial decompositions based on nonoverlapping multidomains, above and below the sea level, are variationally introduced with internal boundary fluxes dualized as weak transmission constraints. Further, parallel augmented and exactly penalized duality algorithms, and proximation semi-implicit time marching schemes, are established and analyzed.

AN EFFICIENT ITERATION ALGORITHM OF MIXED BOUNDARY/FINITE ELEMENT METHOD AND APPLICATION TO FREE TORSIONAL VIBRATION ANALYSIS OF BODIES OF REVOLUTION

In this paper, the general formulation of anew proposed iteration algorithm of mixed BEM/FEM for eigenvalue problems of elastodynamics is described. Approximate fundamental solutions of elastodynamics are adopted in the normal mixed BEM/FEM equations. The accuracy of solutions is progressively improved by the iteration procedure. Not only could the awkwardness of non-algebraic eigenvalue equations be avoided but also the accuracy of numerical solutions is almost independent of the interior meshing. All these give many advantages in numerical calculation. The algorithm is applied to free torsional vibration analysis of bodies of revolution. A few cases are studied. All of the numerical results are very good.

Optimal Redundancy Allocation in Hierarchical Series-Parallel Systems Using Mixed Integer Programming

Reliability optimization plays an important role in design, operation and management of the industrial systems. System reliability can be easily enhanced by improving the reliability of unreliable components and/or by using redundant configuration with subsystems/components in parallel. Redundancy Allocation Problem (RAP) was studied in this research. A mixed integer programming model was proposed to solve the problem, which considers simultaneously two objectives under several resource constraints. The model is only for the hierarchical series-parallel systems in which the elements of any subset of subsystems or components are connected in series or parallel and constitute a larger subsystem or total system. At the end of the study, the performance of the proposed approach was evaluated by a numerical example.

桶混助剂和剂型创新在农药雾滴飘移控制中的应用及研究进展

近年来,随着植保无人机施药技术的迅速发展,农药雾滴飘移引起的药害问题更加凸显。除了降低农药利用率,雾滴飘移还对周围环境造成污染,同时也危害人类健康。雾滴特性、药械参数和施药环境是影响农药雾滴飘移的重要因素,其中雾滴特性直接受到桶混助剂和农药剂型的影响。基于农药助剂和制剂研发应用过程中的理论积累和实践经验,笔者通过分析影响农药雾滴飘移的原因,综述了农药桶混助剂在农药防飘移技术中的研究进展,分析了农药剂型创新在防飘移技术中的潜在用途,并对该领域的发展前景进行展望,以期为通过筛选优良助剂和创新农药剂型来减少农药飘移、提高农药有效利用率提供参考和指导。

几种沼液复配农药对小麦雪霉叶枯病菌的抑制效果研究

[目的]研究几种沼液复配农药对小麦雪霉叶枯病菌的抑制效果,为新型农药的开发奠定基础。[方法]将沼液与多种农药一一复配,并结合滤纸片法、孢子萌发法、菌丝抑制法测定其对雪霉叶枯病病原菌的抑制效果。[结果]滤纸片法中在复配农药作用下菌丝仍几乎长满整个平板;在孢子萌发法中,复配农药对雪霉叶枯病病原菌孢子萌发抑制效果从好到差依次是:霜霉威、井冈霉素、禾康、三唑酮、易保,但它们的EC50值表明,5种农药对雪霉叶枯病病原菌孢子萌发抑制效果都不好;而在菌丝抑制法中,复配农药对雪霉叶枯病菌丝抑制效果从好到差依次是:易保、霜霉威、禾康,由EC50和EC90值可知,易保及霜霉威的抑制效果比较好,其EC50和EC90分别为15和689 mg/L,439和6560 mg/L。[结论]菌丝抑制法是研究复配农药对病原菌抑制效果最有效的方法。

抛物方程一种新混合有限元格式及误差分析

研究二维抛物方程,提出一些新的、Brezzi-Babuska条件自然满足的混合变分格式、关于时间半离散混合格式和全离散化混合有限元格式,并对这些格式做严格误差分析.这种混合有限元格式不但自由度是最少的而且所得到的误差估计也是最优阶的,是对现有格式的改进和发展.

羟丙基胍胶压裂液重复利用技术研究

针对南泥湾采油厂压裂施工后返排液多、处理费用高,研究了羟丙基胍胶压裂液重复利用技术.首先,以羟丙基胍胶为稠化剂,硼砂为交联剂,缓释型SS-1为破胶剂制备可重复利用的压裂液基液.然后在40℃条件下,优化重复利用时破胶液与基液的混合比例,以及向混合液中加入交联剂、破胶剂和交联促进剂的量,满足现场施工60 s内交联、3 h后破胶的要求.通过室内实验确定了重复利用压裂液体系最佳配方:破胶液与基液混合体积比为1∶3,加入交联剂硼砂质量分数0.035%～0.045%,缓释型破胶剂SS-1质量分数0.25%～0.35%,交联促进剂质量分数0.03%～0.06%.性能评价结果表明,该压裂液体系具有良好的流变性和抗剪切性,滤失量小,破胶彻底和残渣低等优良性能,实现了压裂液的重复利用.

球孢白僵菌混合制剂的加工研究

球孢白僵菌混合粉剂是由５１％的孢子粉、２０％紫外保护剂、２５％载体和４％的灭幼脲Ⅲ号，经正交设计优化配方得到。室内生物测定结果表明，此剂对３～４龄马尾松毛虫幼虫ＬＴ５０为５．７ｄ。林间放菌防效达７４．２７％。室温下贮藏０．５ａ，孢子萌发率比高孢粉剂提高１０倍以上。

绿僵菌制剂的剂型及其应用效果

为提高绿僵菌孢子的贮藏和环境稳定性,实验对绿僵菌剂型进行研究。确定产品剂型配方为50%孢子粉,21.5%载体,2%增效剂,1.5%紫外吸收剂,25%的大豆色拉油;室内生物测定结果表明,制剂对3龄东亚飞蝗的半致死时间LT50为5.06d,田间应用防效达到88.9%,在25℃下半衰期为258.6d。