The properties of protective oxide scales containing cerium on alloy 800H in oxidizing and oxidizing/sulphidizing environments

The corrosion protection of oxide scales formed by electrophoretic deposition in a cerium-containing sol on Alloy 800H, a 32Ni-20Cr steel, followed by firing in air at 1123 K was studied in oxidizing and mixed oxidizing/sulphidizing environments at elevated temperatures. In particular, the influence of type of sol solvent, sol concentration, and thickness of deposited layer on the protection were studied. An optimized treatment was deduced which led to a significant improvement in corrosion behavior in oxidizing/sulphidizing environments.     

采用双迭片压电敏感元件的声压梯度水听器

介绍一种采用双选片压电敏感元件的声压梯度水听器．描述了这种水听器的结构设计方法以及实测的指向性、接收灵敏度特性，提出几种可能的变型设计．     

Shape design sensitivity analysis via material derivative-adjoint variable technique for 3-D and 2-D curved boundary elements

A general approach to shape design sensitivity analysis of three- and two-dimensional elastic solid objects is developed using the material derivative-adjoint variable technique and boundary element method. The formulation of the problem is general and first-order sensitivities in the form of boundary integrals for the effect of boundary shape variations are derived for an arbitrary performance functional. Second-order quadrilateral surface elements (for 3-D problems) and quadratic boundary elements (for 2-D problems) are employed in the solution of primary and adjoint systems and discretization of the boundary integral expressions for sensitivities. The accuracy of sensitivity information is studied for selected global performance functionals and also for boundary state fields at discrete points. Numerical results are presented to demonstrate the accuracy and efficiency of this approach.     

An equivalent stiffness approach for modelling the behaviour of compression members according to Eurocode 3

The development of design procedures based on inelastic advanced analysis is a key consideration for future steel design codes. In advanced analysis the effect of imperfections has to be modelled in such a way that the incremental analysis fully captures this effect in the process of moment redistribution. In modelling the influence of imperfections on the behaviour of individual members of real structures, different approaches have been used to globally represent this effect in the overall analysis of structural systems. They are referred to as the initial bow imperfection approach or as the equivalent transverse load approach. When using the abovementioned approaches in analysis of multiple member structural systems, the designer is required to arrange the directions of bow imperfections or equivalent transverse loads in such a way that the imperfection arrangement leads to the least constrained solution, i.e. the lowest ultimate load predicted from all possible sets of member initial imperfection arrangements. Since there is still ongoing research on the development of simple application rules ensuring that the designer obtains a unique solution when choosing a certain set of member initial imperfections, there is at the same time interest in the development of alternative approaches to modelling the influence of member imperfections on the behaviour of structural systems. This paper provides the necessary background information as well as describes the formulation and modelling techniques used in the development of a new approach to modelling the influence of imperfections on the stability behaviour of structural components and systems. This new approach, called hereafter an equivalent stiffness approach, has an advantage over the previously described approaches since an imperfect member is treated as a hypothetically straight element, flexural and axial stiffnesses of which at each load level are predicted in a continuous fashion dependent upon the actual force and deformation states. This type of modelling does not require any explicit modelling of equivalent geometric imperfections or equivalent forces and their directions in advanced analysis; therefore also it does not require any buckling mode assessment. Moreover, the effects of strain hardening and section class may conveniently be included in modelling. Finally, European buckling curves are used to estimate the values of parameters of the developed model that can be immediately used in advanced analysis conducted according to Eurocode 3.     

PSRI elements for the Reissner–Mindlin free plate

The Reissner–Mindlin plate model in presence of free boundary conditions is considered. It is known that in this case the solution can suffer, for small thickness, from some boundary layer effects that reduce the regularity of the solution, in particular of the rotations and shear strains. This causes a loss of convergence order in the numerical approximation. For this reason a new model that modifies the free boundary conditions is considered. The approximation of this new model by means of an element of low degree of the partial selective reduced integration family has been analyzed both from the theoretical and the numerical point of view. Some numerical results have been presented showing the performance of this element when applied to free plates.     

稀土在人棉灯芯绒直接染料染色中的应用

目前，稀土在化纤类，毛类纺织品染色中的应用比较成熟，而在棉类染色中的应用还未能得到推广，探讨稀土在直接染料对人棉灯芯绒织物染色中的作用机理，并从试验和生产方面加以比较，总结出本厂的成熟工艺。作者认为稀土对人棉灯芯绒织物在直接染料染色上应用是切实可行的，效果是理想的。     

气象条件对舰载火箭炮系统射击的影响与修正

以提高某型舰载火箭炮射击精度为出发点，探讨了气象参数对火箭炮射击精度的影响及火控解算修正方法，进一步提出了研制GPS目标指示弹和电视侦察弹以解决气象对射击精度影响的根本问题。     

A triangular hybrid equilibrium plate element of general degree

Hybrid stress‐based finite elements with side displacement fields have been used to generate equilibrium models having the property of equilibrium in a strong form. This paper establishes the static and kinematic characteristics of a flat triangular hybrid equilibrium element with both membrane and plate bending actions of general polynomial degree p. The principal characteristics concern the existence of hyperstatic stress fields and spurious kinematic modes. The former are shown to exist for p>3, and their significance to finite element analysis is reviewed. Knowledge of the latter is crucial to the determination of the stability of a mesh of triangular elements, and to the choice of procedure adopted for the solution of the system of equations. Both types of characteristic are dependent on p, and are established as regards their numbers and general algebraic forms. Graphical illustrations of these forms are included in the paper. Copyright © 2005 John Wiley & Sons, Ltd.     

Simulation results of arc behavior in different plasma spray torches

Three-dimensional, transient simulations of the plasma flow inside different plasma spray torches have been performed using a local thermodynamic equilibrium model solved by a multiscale finite-element method. The model describes the dynamics of the arc without any further assumption on the reattachment process except for the use of an artificially high electrical conductivity near the electrodes. Simulations of an F4-MB torch from Sulzer-Metco and two configurations of the SG-100 torch from Praxair are presented. The simulations show that, when straight or swirl injection is used, the arc is dragged by the flow and then jumps to form a new attachment, preferably at the opposite side of the original attachment, as has been observed experimentally. Although the predicted reattachment frequencies are at present higher than the experimental ones, the model is suitable as a design tool. This article was originally published inBuilding on 100 Years of Success: Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

Edge Stress Intensity Functions in Polyhedral Domains and their Extraction by a Quasidual Function Method

The solution to elastic isotropic problems in three-dimensional (3-D) polyhedral domains in the vicinity of an edge is provided in an explicit form. It involves a family of eigen-functions with their shadows, and the associated edge stress intensity functions (ESIFs), which are functions along the edges. Utilizing the explicit structure of the solution in the vicinity of the edge we use the quasidual function method, recently presented in [Omer et al. (2004). International Journal of Fracture 129:97–130] for scalar elliptic problems and in [Costabel et al. (2004). SIAM Journal of Mathematical Analysis 35(5), 1177–1202] in a general theoretical framework, for the extraction of ESIFs. This method provides a polynomial approximation of the ESIF along the edge whose order is adaptively increased so to approximate the exact ESIF. It is implemented as a post-solution operation in conjunction with the p-version finite element method. Numerical examples are provided in which we extract ESIFs associated with traction free or homogeneous Dirichlet boundary conditions in 3-D cracked domains or 3-D V-Notched domains. These demonstrate the efficiency, robustness and high accuracy of the proposed quasi-dual function method.