Topologically Finite Intersection Property and Minimax Theorems

A more general lopologically finite intersection property is obtained. As anapplication,we utilize this result to obtain some more general minimax theorems. Theresults presented in this paper unify and extend the main results of [5, 6, 9].

Effect of Dimension Parameters on the Torsion Property of A C/SiC Pipe

Through finite element numerical simulation and based on laminated plate theory, the effect of dimension on the torsion properties of uniform C/SiC composites pipe was studied to provide a theoretical guidance for preparing the C/SiC pipe with different dimensions. The results show that, with increasing length of pipe, the anti-torsion section coefficient of pipe increases whereas the torsion angle per unit length decreases. Increasing the length can improve the torsion property. Anti-torsion section coefficient rises with increasing internal radius, while the torsion angle per unit length decreases to a constant. With increasing thickness, the anti-torsion section coefficient increases whereas the amplitude decreases gradually, and the torsion angle per unit length is a constant. Increment of internal radius and thickness improves the torsion property finitely.

NEW SIMPLE SMOOTH MERIT FUNCTION FOR BOX CONSTRAINED VARIATIONAL INEQUALITIES AND DAMPED NEWTON TYPE METHOD

By introducing a smooth merit function for the median function, a new smooth merit function for box constrained variational inequalities （BVIs） was constructed. The function is simple and has some good differential properties. A damped Newton type method was presented based on it. Global and local superlinear/ quadratic convergence results were obtained under mild conditions, and the finite termination property was also shown for the linear BVIs. Numerical results suggest that the method is efficient and promising.

An Average Failure Index Method for the Tensile Strength Prediction of Composite Adhesive-bonded π Joints

An average failure index method based on accurate FEA was proposed for the tensile strength prediction of composite out-of-plane adhesive-bonded π joints. Based on the simple and independent maximum stress failure criterion, the failure index was introduced to characterize the degree of stress components close to their corresponding material strength. With a brief load transfer analysis, the weak fillers were prominent and further detailed discussion was performed. The maximum value among the average failure indices which were related with different stress components was filtrated to represent the failure strength of the critical surface, which is either the two curved upside surfaces or the bottom plane of the fillers for composite π joints. The tensile strength of three kinds of π joints with different material systems, configurations and lay-ups was predicted by the proposed method and corresponding experiments were conducted. Good agreements between the numerical and experimental results give evidence of the effectiveness of the proposed method. In contrast to the existed time-consuming strength prediction methods, the proposed method provides a capability of quickly assessing the failure of complex out-of-plane joints and is easy and convenient to be widely utilized in engineering.

Finite Sample Properties of Virtual Reference Feedback Tuning Control

In this paper, finite sample properties of virtual reference feedback tuning control are considered, by using the theory of finite sample properties from system identification. To design a controller in closed loop system structure, the idea of virtual reference feedback tuning is proposed to avoid the identification process corresponding to the plant model. After constructing one identification cost without any knowledge of plant model, the author derives one bound on the difference between the expected identification cost and its sample identification cost under the condition that the number of data points is finite. Also the correlation between the plant input and external noise is considered in the derivation of this bound. Furthermore, the author continues to derive one probability bound to quantify this difference by using some probability inequalities and control theory.

Effects of Cooling Paths on Through-Thickness Microstructure and Mechanical Properties of Heavy Gauge X80 Pipeline Steel

The effects of various cooling paths on uniformity of through-thickness microstructure and mechanical properties of X80 pipeline steel of 22.0 mm in thickness were studied. The finite difference method was employed to calculate the temperature field during cooling. It was confirmed by the experimental result and temperature field calculation that the optimizing process was achieved by the ultra-fast cooling with medium cooling capacity（cooling rate of ＊23 K/s）followed by ultimate cooling capacity（cooling rate of ＊50 K/s）. After optimization, the experimental steel displayed much uniform microstructure and the deviation of through-thickness hardness was controlled within 20 HV. In addition,the yield strength, tensile strength and elongation of the experimental steel were 621, 728 MPa and 21.5%, respectively,meeting the requirements of the API standard for X80 pipeline steels.