摘要：
Non-probabilistic convex model utilizes a convex set to quantify the uncertainty domain of uncertain-but-bounded parameters, which is very effective for structural uncertainty analysis with limited or poor-quality experimental data. To overcome the complexity and diversity of the formulations of current convex models, in this paper, a unified framework for construction of the non-probabilistic convex models is proposed. By introducing the correlation analysis technique, the mathematical expression of a convex model can be conveniently formulated once the correlation matrix of the uncertain parameters is created. More importantly, from the theoretic analysis level, an evaluation criterion for convex modelling methods is proposed, which can be regarded as a test standard for validity verification of subsequent newly proposed convex modelling methods. And from the practical application level, two model assessment indexes are proposed, by which the adaptabilities of different convex models to a specific uncertain problem with given experimental samples can be estimated. Four numerical examples are investigated to demonstrate the effectiveness of the present study. (C) 2018 Elsevier Inc. All rights reserved.
摘要：
A novel LS-SVM control method is proposed for general unknown nonlinear systems. A linear kernel LS-SVM model is firstly developed for input/output (I/O) approximation. The LS-SVM control law is then derived directly from this developed model without any approximation and assumption. It further proves that the control error is fully equal to the LS-SVM modeling error. This means that a desirable control performance can be achieved because the LS-SVM has been proven to have an outstanding modeling ability in the previous studies. Case studies finally demonstrate the effectiveness of the proposed LS-SVM control approach.
摘要：
Use of multidisciplinary analysis in reliability-based design optimization (RBDO) results in the emergence of the important method of reliability-based multidisciplinary design optimization (RBMDO). To enhance the efficiency and convergence of the overall solution process, a decoupling algorithm for RBMDO is proposed herein. Firstly, to decouple the multidisciplinary analysis using the individual disciplinary feasible (IDF) approach, the RBMDO is converted into a conventional form of RBDO. Secondly, the incremental shifting vector (ISV) strategy is adopted to decouple the nested optimization of RBDO into a sequential iteration process composed of design optimization and reliability analysis, thereby improving the efficiency significantly. Finally, the proposed RBMDO method is applied to the design of two actual electronic products: an aerial camera and a car pad. For these two applications, two RBMDO models are created, each containing several finite element models (FEMs) and relatively strong coupling between the involved disciplines. The computational results demonstrate the effectiveness of the proposed method.
关键词：
Most probable point (MPP);performance measure approach (PMA);reliability-based design optimization (RBDO);time-variant reliability;stochastic process
摘要：
Although a series of decoupled or single loop methods have been developed for reliability-based design optimization (RBDO) problems to improve the computational efficiency, it seems hard to extend these strategies to time-variant RBDO due to the complexity of the problems brought by the involvement of time. This paper proposes a new approach for time-variant reliability-based design optimization, expecting to provide an efficient tool for design of some complex structure under time-variant uncertainties. The main idea of the proposed method is the definition of the equivalent most probable point (EMPP). With the EMPP, the original time-variant RBDO problem can be transformed into an equivalent time-invariant RBDO problem formulated by performance measure approach (PMA). Hence, the existing PMA-based time-invariant RBDO methods can be applied to solve the equivalent problem. Therefore, those RBDO methods can be easily extended to time-variant RBDO problems, and hence the computational cost can be effectively reduced. Finally, two numerical examples and an engineering application are used to demonstrate the effectiveness of the proposed method.
摘要：
Conventional decoupling approaches usually employ first-order reliability method to deal with probabilistic constraints in a reliability-based design optimization problem. In first-order reliability method, constraint functions are transformed into a standard normal space. Extra non-linearity introduced by the non-normal-to-normal transformation may increase the error in reliability analysis and then result in the reliability-based design optimization analysis with insufficient accuracy. In this article, a decoupling approach is proposed to provide an alternative tool for the reliability-based design optimization problems. To improve accuracy, the reliability analysis is performed by first-order asymptotic integration method without any extra non-linearity transformation. To achieve high efficiency, an approximate technique of reliability analysis is given to avoid calculating time-consuming performance function. Two numerical examples and an application of practical laptop structural design are presented to validate the effectiveness of the proposed approach.
摘要：
Summary: Polyaniline (PANI) nanowires and sub‐micro/nanostructured dendrites are synthesized and immobilized on PP‐g‐PAA film surfaces via routine oxidative polymerization of aniline under different conditions, where grafting poly(acrylic acid) (PAA) served as a template and dopant, and SDS as a surfactant. The immobilized PANI enhances the surface hydrophilicity of the poly(propylene) (PP) films, and a superhydrophilic surface is obtained in this way. The mechanism of forming different morphologies of PANI and of correspondingly obtaining a superhydrophilic surface are briefly discussed. FESEM image shows the PANI sub‐micro/nanostructured dendrites immobilized on the surfaces of PP films. The modified surface is highly hydrophilic with a water contact angle of 3°.
摘要：
Featured Application This paper develops an evidence-theory-based robustness optimization (EBRO) method, which aims to provide a potential computational tool for engineering problems with epistemic uncertainty. This method is especially suitable for robust designing of micro-electromechanical systems (MEMS). On one hand, unlike traditional engineering structural problems, the design of MEMS usually involves micro structure, novel materials, and extreme operating conditions, where multi-source uncertainties inevitably exist. Evidence theory is well suited to deal with such uncertainties. On the other hand, high performance and insensitivity to uncertainties are the fundamental requirements for MEMS design. The robust optimization can improve performance by minimizing the effects of uncertainties without eliminating these causes. Abstract The conventional engineering robustness optimization approach considering uncertainties is generally based on a probabilistic model. However, a probabilistic model faces obstacles when handling problems with epistemic uncertainty. This paper presents an evidence-theory-based robustness optimization (EBRO) model and a corresponding algorithm, which provide a potential computational tool for engineering problems with multi-source uncertainty. An EBRO model with the twin objectives of performance and robustness is formulated by introducing the performance threshold. After providing multiple target belief measures (Bel), the original model is transformed into a series of sub-problems, which are solved by the proposed iterative strategy driving the robustness analysis and the deterministic optimization alternately. The proposed method is applied to three problems of micro-electromechanical systems (MEMS), including a micro-force sensor, an image sensor, and a capacitive accelerometer. In the applications, finite element simulation models and surrogate models are both given. Numerical results show that the proposed method has good engineering practicality due to comprehensive performance in terms of efficiency, accuracy, and convergence.
作者机构：
[李欣然; 陈鸿琳] College of Electrical and Information Engineering, Hunan Univ, Changsha, Hunan, 410082, China;[陈国民] School of Mechanical and Electrical Engineering, Hunan City Univ, Yiyang, Hunan, 413000, China;[冷华] Electrical Research Institute of State Grid Hunan Electric Power Company, Changsha, Hunan, 410007, China
通讯机构：
College of Electrical and Information Engineering, Hunan Univ, Changsha, Hunan, China
作者机构：
[阳同光] College of Mechanical and Electrical Engineering, Hunan City University, Yiyang, 413000, China;[阳同光; 桂卫华] College of Information Science and Engineering, Central South University, Changsha, 410083, China
通讯机构：
College of Mechanical and Electrical Engineering, Hunan City University, Yiyang, China
作者机构：
[Zhong, WB] Hunan Univ, Coll Mat Sci & Engn, Changsha 410082, Peoples R China.;Hunan City Univ, Dept Mech, Yiyang 413000, Peoples R China.;Beijing Inst Chem Technol, Dept Polymer Sci, Beijing 100029, Peoples R China.
通讯机构：
[Zhong, WB] Hunan Univ, Coll Mat Sci & Engn, Changsha 410082, Peoples R China.
摘要：
Polypyrrole (PPy) nanowire networks have been synthesized in high yield (higher than 90%) by chemical oxidative polymerization of pyrrole in the presence of hexadecyltrimethylammonium bromide (HTAB) and organic diacids (oxalic acid, tartaric acid, or glutaric acid) and triacid (citric acid). The diameter of nanowire is 60−90 nm. The influence of reaction conditions, such as polymerization temperature, polymerization time, and the molar ratios of HTAB to organic acids and pyrrole, on the morphologies of the PPy nanowire networks has been systematically investigated. In addition, the interconnected PPy nanoparticles are prepared without using HTAB. The film of PPy nanowire networks and nanoparticles is superhydrophilic. A plausible formation mechanism of PPy nanowire networks is discussed.
作者机构：
[阳同光] College of Mechanical and Engineering, Hunan City University, Yiyang, 413000, China;[阳同光; 桂卫华] College of Information Science and Engineering, Central South University, Changsha, 410083, China
通讯机构：
College of Mechanical and Engineering, Hunan City University, Yiyang, China
作者机构：
[潘晴; 范彬] College of Mechanical and Electrical Eng., Central South University, Changsha, 410083, China;[范彬] College of Mechanical and Electrical Eng., Hunan City Univ., Yiyang, 413002, China
