Multidisciplinary robust design optimization based on time-varying sensitivity analysis

Huanwei Xu,Wei Liao,Mufeng Li,Cong Hu,Suichuan Zhang,Xin Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3

The performance of complex mechanical systems often degrades over time primarily due to time-varying uncertainties. Improving the design of such systems entails addressing time-varying uncertainties through multidisciplinary design optimization (MDO). In this study, a multidisciplinary robust design optimization method that is based on time-varying sensitivity analysis is proposed. First, the indices for the time-varying reliability sensitivity of limit state functions are calculated by combining sensitivity analysis and an empirical correction formula. The propagation effects of these time-varying uncertainties are qualified by combining the simplified implicit uncertainty propagation and sequential quadratic programming methods. Finally, the robust design method is integrated with MDO to reduce the effects of time-varying uncertainties. The feasibility and effectiveness of the proposed method are illustrated with a mathematical problem and an engineering example.

Research on crow swarm intelligent search optimization algorithm based on surrogate model

Huanwei Xu,Liangwen Liu,Miao Zhang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.10

A large amount of calculation exists in a complex engineering optimization problem. The swarm intelligence algorithm can improve calculation efficiency and accuracy of complex engineering optimization. In the existing research, the surrogate model and the swarm intelligence algorithm are only two independent tools to solve the optimization problem. In this paper, we propose the surrogate-assisted crow swarm intelligent search optimization algorithm (SACSA) by combining the characteristics of swarm intelligence algorithm and surrogate model. The proposed algorithm utilizes the initial samples to construct the surrogate model, and then the improved crow search algorithm (CSA) is applied to obtain optimal solution. Finally, the proposed algorithm is compared with EGO, MSSR, ARSM-ISES, AMGO and SEUMRE, MPS, HAM algorithms. The comparison results show that the proposed algorithm can find a global optimal solution with fewer samples and is beneficial to improving the efficiency and accuracy of calculation.

A New Spatial Deformation Measurement Method Using 3D Reconstruction Technology during Pile Penetration

Cong Liu,Xiaowei Tang,Huanwei Wei,Honghua Zhao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

Non-intrusive observation of the spatial deformation field of the soil has been a difficult problem for model test measurements. Based on the advantage that the visualization test method of transparent soil can observe the two-dimensional (2D) deformation inside the soil, this study proposes a new automatic tomographic scanning measuring device to observe the three-dimensional (3D) spatial soil deformation inside the transparent soil model. A series of 2D laser speckle images of different vertical cross sections before and after deformation were obtained, and an improved 3D reconstruction algorithm was used to reconstruct the 3D displacement field of soil after deformation. Different types of jacked-pile penetration model tests were carried out to investigate the spatial disturbance of the soil around the pile caused by the squeezing effect of the jacked-pile. The test results showed that the developed novel automatic tomographic scanning measuring device with the modified 3D reconstruction procedure could be an innovative tool in geotechnical physical model experiments. The model test results visually revealed the mechanism of the soil squeezing effect of jacked-piles with different pile head forms. Moreover, the spatial disturbance effect caused by different penetration stages was also discussed herein.

A novel non-probabilistic approach using interval analysis for robust design optimization

Wei Sun,Rongmei Dong,Huanwei Xu 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.12

A technique for formulation of the objective and constraint functions with uncertainty plays a crucial role in robust design optimization. This paper presents the first application of interval methods for reformulating the robust optimization problem. Based on interval mathematics, the original real-valued objective and constraint functions are replaced with the interval-valued functions, which directly represent the upper and lower bounds of the new functions under uncertainty. The single objective function is converted into two objective functions for minimizing the mean value and the variation, and the constraint functions are reformulated with the acceptable robustness level, resulting in a bi-level mathematical model. Compared with other methods, this method is efficient and does not require presumed probability distribution of uncertain factors or gradient or continuous information of constraints. Two numerical examples are used to illustrate the validity and feasibility of the presented method.

Model Tests of Jacked-Pile Penetration into Sand Using Transparent Soil and Incremental Particle Image Velocimetry

Cong Liu,Xiao-Wei Tang,Huanwei Wei,Pengpeng Wang,Honghua Zhao 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

This paper presents a series of physical modelling tests of jacked-pile penetration into sand, combining the transparent soil and incremental reliability-guided particle image velocimetry, which provides a non-intrusively internal deformation measurement approach to monitor the internal movement of soil caused by jacked-pile penetration. The difference between the full-model test and the half-model test was analyzed quantitatively for the first time. This paper aims to provide some new insight into the penetration mechanisms of different shapes of pile tip. In addition, the phenomenon of meta-stable sand plug in the process of jacked-pile penetration was studied by means of the method of partial replacement with dyed particles. Experimental evidence has shown that the boundary and interaction effect causes the experimental phenomenon of the half-model test to be different from the true condition. The shape effect of pile tip on the governing penetration mechanisms was discussed, and the disturbance effect of different shapes of pile tip was evaluated and compared based on a large number of model tests and published literatures. The paper intuitively demonstrates that the different penetration mechanism of flat-ended pile and cone-ended pile is mainly due to the formation of the meta-stable sand plug beneath the pile tip.

Dietary phosphorus deficiency impaired growth, intestinal digestion and absorption function of meat ducks

Huimin Xu,Shujun Dai,Keying Zhang,Xuemei Ding,Shiping Bai,Jianping Wang,Huanwei Peng,Qiufeng Zeng 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.12

Objective: An experiment was conducted to investigate the effects of dietary non-phytate phosphorus (nPP) deficiency on intestinal pH value, digestive enzyme activity, morphology, nutrient utilization, and gene expression of NaPi-IIb in meat ducks from 1 to 21 d of age. Methods: A total of 525 one-d-old Cherry Valley ducklings were fed diets (with 7 pens of 15 ducklings, or 105 total ducklings, on each diet) with five levels of nPP (0.22%, 0.34%, 0.40%, 0.46%, or 0.58%) for 21 d in a completely randomized design. Five experimental diets contained a constant calcium (Ca) content of approximately 0.9%. Body weight (BW), body weight gain (BWG), feed intake (FI), and feed to gain ratio (F:G) were measured at 14 and 21 d of age. Ducks were sampled for duodenum and jejunum digestion and absorption function on 14 and 21 d. Nutrient utilization was assessed using 25- to 27-d-old ducks. Results: The results showed ducks fed 0.22% nPP had lower (p<0.05) growth performance and nutrient utilization and higher (p<0.05) serum Ca content and alkaline phosphatase (ALP) activity. When dietary nPP levels were increased, BW (d 14 and 21), BWG and FI (all intervals), and the serum phosphorus (P) content linearly and quadratically increased (p<0.05); and the jejunal pH value (d 14), duodenal muscle layer thickness (d 14), excreta dry matter, crude protein, energy, Ca and total P utilization linearly increased (p<0.05); however, the serum ALP activity, jejunal Na+-K+-ATPase activity, and duodenal NaPi-IIb mRNA level (d 21) linearly decreased (p<0.05). Conclusion: The results indicated that ducks aged from 1 to 21 d fed diets with 0.22% nPP had poor growth performance related to poor intestinal digestion and absorption ability; but when fed diets with 0.40%, 0.46%, and 0.58% nPP, ducks presented a better growth performance, intestinal digestion and absorption function.