A hybrid algorithm for reliability analysis combining Kriging and subset simulation importance sampling

Cao Tong,Zhili Sun,Qianli Zhao,Qibin Wang,Shuang Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

To solve the problem of large computation when failure probability with time-consuming numerical model is calculated, we proposean improved active learning reliability method called AK-SSIS based on AK-IS algorithm [1]. First, an improved iterative stopping criterionin active learning is presented so that iterations decrease dramatically. Second, the proposed method introduces Subset simulationimportance sampling (SSIS) into the active learning reliability calculation, and then a learning function suitable for SSIS is proposed. Finally, the efficiency of AK-SSIS is proved by two academic examples from the literature. The results show that AK-SSIS requiresfewer calls to the performance function than AK-IS, and the failure probability obtained from AK-SSIS is very robust and accurate. Thenthis method is applied on a spur gear pair for tooth contact fatigue reliability analysis.

Sequence analysis of the spike gene of Porcine epidemic diarrhea virus isolated from South China during 2011–2015

Xiaoya Zhao,Zhili Li,Xiduo Zeng,Guanqun Zhang,Jianqiang Niu,Baoli Sun,Jingyun Ma 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.2

The spike gene of porcine epidemic diarrhea virus (PEDV) was sequenced from 55 South China field strains isolated from pigs with symptoms of diarrhea. The sequences were compared within the set of field strains as well as with reference strains available in GenBank. Within the 55 South China PEDV field strains, the deduced amino acid sequence identities ranged from 93.8% to 99.9 % and ranged from 90.7% to 99.5% when compared with the foreign reference strains in GenBank. Our phylogenetic analysis showed that 10 of the 55 South China PEDV strains belonged to G1b and 45 belonged to G2b.

An efficient reliability analysis strategy for low failure probability problems

Runan Cao,Zhili Sun,Jian Wang,Fanyi Guo 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.2

For engineering, there are two major challenges in reliability analysis. First, to ensure the accuracy of simulation results, mechanical products are usually defined implicitly by complex numerical models that require time-consuming. Second, the mechanical products are fortunately designed with a large safety margin, which leads to a low failure probability. This paper proposes an efficient and high-precision adaptive active learning algorithm based on the Kriging surrogate model to deal with the problems with low failure probability and time-consuming numerical models. In order to solve the problem with multiple failure regions, the adaptive kernel-density estimation is introduced and improved. Meanwhile, a new criterion for selecting points based on the current Kriging model is proposed to improve the computational efficiency. The criterion for choosing the best sampling points considers not only the probability of misjudging the sign of the response value at a point by the Kriging model but also the distribution information at that point. In order to prevent the distance between the selected training points from too close, the correlation between training points is limited to avoid information redundancy and improve the computation efficiency of the algorithm. Finally, the efficiency and accuracy of the proposed method are verified compared with other algorithms through two academic examples and one engineering application.

A novel reliability analysis method based on Gaussian process classification for structures with discontinuous response

Yibo Zhang,Zhili Sun,Yutao Yan,Zhenliang Yu,Jian Wang 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.6

Reliability analysis techniques combining with various surrogate models have attracted increasing attention because of their accuracy and great efficiency. However, they primarily focus on the structures with continuous response, while very rare researches on the reliability analysis for structures with discontinuous response are carried out. Furthermore, existing adaptive reliability analysis methods based on importance sampling (IS) still have some intractable defects when dealing with small failure probability, and there is no related research on reliability analysis for structures involving discontinuous response and small failure probability. Therefore, this paper proposes a novel reliability analysis method called AGPC-IS for such structures, which combines adaptive Gaussian process classification (GPC) and adaptive-kernel-density-estimation-based IS. In AGPC-IS, an efficient adaptive strategy for design of experiments (DoE), taking into consideration the classification uncertainty, the sampling uniformity and the regional classification accuracy improvement, is developed with the purpose of improving the accuracy of Gaussian process classifier. The adaptive kernel density estimation is introduced for constructing the quasi-optimal density function of IS. In addition, a novel and more precise stopping criterion is also developed from the perspective of the stability of failure probability estimation. The efficiency, superiority and practicability of AGPC-IS are verified by three examples.

A general active-learning method for surrogate-based structural reliability analysis

Congyi Zha,Zhili Sun,Jian Wang,Chenrong Pan,Zhendong Liu,Pengfei Dong 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.2

Surrogate models aim to approximate the performance function with an active-learning design of experiments (DoE) to obtain a sufficiently accurate prediction of the performance function’s sign for an inexpensive computational demand in reliability analysis. Nevertheless, many existing active-learning methods are limited to the Kriging model, while the uncertainties of the Kriging itself affect the reliability analysis results. Moreover, the existing general active-learning methods may not achieve a fully satisfactory balance between accuracy and efficiency. Therefore, a novel active-learning method GLM- CM is constructed to yield the issues, which conciliates several merits of existing methods. To demonstrate the performance of the proposed method, four examples, concerning both mathematical and engineering problems, were selected. By benchmarking obtained results with literature findings, various surrogate models combined with the proposed method not only provide an accurate reliability evaluation while highly alleviating the computational burden, but also provides a satisfactory balance between accuracy and efficiency compared to the other reliability methods.

Genetic diversity and phylogenetic analysis of porcine reproductive and respiratory syndrome virus in southern China from 2007 to 2014

Qiwen Wu,Zhili Li,Guanqun Zhang,Jianqiang Niu,Xiduo Zeng,Baoli Sun,Jingyun Ma 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.3

Porcine reproductive and respiratory syndrome virus (PRRSV) has a high degree of genetic variation. In this study, we characterized the genetic variation and evolutionary relationships among circulating PRRSV strains in southern China. We analyzed 29 NSP2 strains and 150 ORF5 strains from clinical samples collected in southern China during 2007–2014. The alignment results showed that the nucleotide identity similarities of the two genes among these strains were 80.5%–99.7% and 80.9%–100%, respectively. Phylogenetic analysis based on the NSP2 gene showed that highly pathogenic (HP)-PRRSV was still the dominant virus in southern China from 2013 to 2014. Compared with reference strains CH-1a and VR-2332, the field strain 131101-GD-SHC, which shared high homology with JXA1-P170, had a novel 12 amino acid deletion at position 499-510. Phylogenetic analysis based on the ORF5 gene showed that HP-PRRSV, VR2332-like strains, and QYYZ-like strains were simultaneously circulating in southern China from 2007 to 2014, suggesting that, in recent years, the type 2 PRRSV was more diverse in southern China. In conclusion, mutations in the decoy epitope and primary neutralizing epitope could be markers of viral evolution and used to study evolutionary relationships among PRRSV strains in China.

Cellular uptake mechanism and comparative in vitro cytotoxicity studies of monomeric LMWP-siRNA conjugate

Junxiao Ye,Xing Pei,Hui Cui,Zhili Yu,이혁진,Jian-Xin Wang,Xu Wang,Lu Sun,Huining He,Victor C. Yang 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

The covalent attachment of CPPs to siRNA molecules offers great potential for CPP-mediated siRNA delivery. We recently reported a concise and high-yield synthesis strategy of the cell-permeable, cytosol-dissociable LMWP-siRNA covalent conjugate. Herein, cell uptake mechanism and cellular toxicity studies of this conjugate were performed to evaluate the potential of LMWP-siRNA conjugate for clinical translation. Cellular uptake mechanism study indicated that the conjugate could be taken up by cells via multiple pathways, including direct penetration of the plasma membrane and clathrin- and caveolae-independent endocytosis. In vitro cytotoxicity study revealed that the conjugation promoted internalization in a low-toxic fashion.

RNA polymerase I subunit D activated by Yin Yang 1 transcription promote cell proliferation and angiogenesis of colorectal cancer cells

Shan Jianfeng,Liang Yuanxiao,Yang Zhili,Chen Wenshan,Chen Yun,Sun Ke 대한약리학회 2024 The Korean Journal of Physiology & Pharmacology Vol.28 No.3

This study aims to explore possible effect of RNA polymerase I subunit D (POLR1D) on proliferation and angiogenesis ability of colorectal cancer (CRC) cells and mechanism herein. The correlation of POLR1D and Yin Yang 1 (YY1) expressions with prognosis of CRC patients in TCGA database was analyzed. Quantitative realtime polymerase chain reaction (qRT-PCR) and Western blot were applied to detect expression levels of POLR1D and YY1 in CRC cell lines and CRC tissues. SW480 and HT- 29 cells were transfected with si-POLR1D or pcDNA3.1-POLR1D to achieve POLR1D suppression or overexpression before cell migration, angiogenesis of human umbilical vein endothelial cells were assessed. Western blot was used to detect expressions of p38 MAPK signal pathway related proteins and interaction of YY1 with POLR1D was confirmed by dual luciferase reporter gene assay and chromatin immunoprecipitation (ChIP). TCGA data showed that both POLR1D and YY1 expressions were up-regulated in CRC patients. High expression of POLR1D was associated with poor prognosis of CRC patients. The results showed that POLR1D and YY1 were highly expressed in CRC cell lines. Inhibition or overexpression of POLR1D can respectively suppress or enhance proliferation and angiogenesis of CRC cells. YY1 inhibition can suppress CRC progression and deactivate p38 MAPK signal pathway, which can be counteracted by POLR1D overexpression. JASPAR predicted YY1 can bind with POLR1D promoter, which was confirmed by dual luciferase reporter gene assay and ChIP. YY1 transcription can up-regulate POLR1D expression to activate p38 MAPK signal pathway, thus promoting proliferation and angiogenesis ability of CRC cells

Cellular uptake mechanism and comparative <i>in vitro</i> cytotoxicity studies of monomeric LMWP-siRNA conjugate

Ye, Junxiao,Pei, Xing,Cui, Hui,Yu, Zhili,Lee, Hyukjin,Wang, Jianxin,Wang, Xu,Sun, Lu,He, Huining,Yang, Victor C. THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.63 No.-

<P><B>Abstract</B></P> <P>The covalent attachment of CPPs to siRNA molecules offers great potential for CPP-mediated siRNA delivery. We recently reported a concise and high-yield synthesis strategy of the cell-permeable, cytosol-dissociable LMWP-siRNA covalent conjugate. Herein, cell uptake mechanism and cellular toxicity studies of this conjugate were performed to evaluate the potential of LMWP-siRNA conjugate for clinical translation. Cellular uptake mechanism study indicated that the conjugate could be taken up by cells via multiple pathways, including direct penetration of the plasma membrane and clathrin- and caveolae-independent endocytosis. <I>In vitro</I> cytotoxicity study revealed that the conjugation promoted internalization in a low-toxic fashion.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A lightweight authentication and privacy-preserving scheme for VANETs using TESLA and Bloom Filters

Shihan Bao,Waleed Hathal,Haitham Cruickshank,Zhili Sun,Phillip Asuquo,Ao Lei 한국통신학회 2018 ICT Express Vol.4 No.4

In Vehicular Ad hoc Networks (VANETs), broadcasted beacon messages are critical as most safety applications rely on them. However, the design of a secure broadcast authentication faces many security and privacychallenges as vehicles are vulnerable to active attacks and the revealing of location. In this paper, we propose a lightweight authentication scheme using Timed Efficient Stream Loss-Tolerant Authentication (TESLA) scheme and Bloom Filters that not only prevents active attacks but also adds a privacy-preserving feature to make the scheme have better performance. Simulation results indicate the scheme outperforms the existing schemes in terms of verification time and the level of anonymity.