Novel AutomaticWorkpiece Surface Defects Detection System

Wenkai Xin,Wei Liu,Kun Yan 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11

An automatic workpiece surface defect detection system based on machine vision is proposed. In order to solve the difficulty of detecting surface defects of irregular workpieces, the system adopts seven shooting stations to collect pictures of workpieces from different angles. Then the pictures of each station are processed at the same time. Advanced image processing algorithms are proposed to detect defects on highly reflective metal surfaces. Finally, the processing results of all stations are combined together to determine whether the workpieces are qualified or not. Tested in real industrial environments, our proposed system achieves a detection accuracy of 99.7%. On average one hundred workpieces can be inspected per minute.

Numerical Simulation of Edge Effect in Resin Transfer Molding for Plain-weave Fabric

Wenkai Yang,Shihong Lu,Wenhao Liu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.9

Plain-weave fabric is a kind of fiber preform which has been commonly used in resin transfer molding (RTM) tomanufacture polymer composites. However, the edge area of plain-weave fabric is easy to shed yarns which will cause theuneven distribution of permeability between edge channel and center of mold in filling process of RTM. Meanwhile, theuneven distribution of permeability will cause the edge effect and seriously affect the final quality of composite materials. Inthis paper, a method to numerically calculate the permeability of edge channel which fully considers the edge area of plainweavefabric is proposed. The experiment and simulation of edge effect in filling process are performed. The results showthat the simulation of edge effect which applies the edge channel’s permeability calculated by this method are in goodagreement with the experimental results. The research in this paper is meaningful to improve the accuracy of edge effectsimulation so as to provide a reference for the design of mold structure.

Effect of Oxygen Functionalities of Graphene Oxide on Polymerization and Thermal Properties of Reactive Benzoxazine Nanocomposites

Wenkai Zhang,Yanshan Zhan,Xiuxiu Gao,Runming Li,Weiwei Zhu,Hao Xu,Baoying Liu,Xiaomin Fang,Yuanqing Xu,Tao Ding 한국고분자학회 2018 Macromolecular Research Vol.26 No.1

Herein, we report the effect of oxygen functionalities of graphene oxide on thermal activated polymerization and thermal properties of reactive benzoxazine nanocomposites. The numbers of oxygen moieties of graphene oxide (GO) are controlled by hydrothermal reduction. The polymerization behavior of benzoxazine monomer (BA-a) is studied by Fourier transform infrared spectroscopy, differential scanning calorimetry and rheological analysis. It is hypothesized that the GO not only exhibits accelerated effect on the polymerization of the BA-a, but also the oxygen moieties such as carboxyl groups of GO interact with the benzoxazine polymers, leading to several orders of magnitude increase in the chemoviscosity and modulus of composite system. Thermal conductivity of poly(BA-a)/GO composite increases from an initial value of ∼0.27 W/mK to 0.47 W/mK as the loading increases from 1 wt% to 6 wt% (enhancement factor up to 176%). Moreover, the nanocomposites display enhanced initial decomposition temperature and char yields as the degree of GO reduction increases.

A Hierarchical Bilateral-Diffusion Architecture for Color Image Encryption

Menglong Wu,Yan Li,Wenkai Liu 한국정보처리학회 2022 Journal of information processing systems Vol.18 No.1

During the last decade, the security of digital images has received considerable attention in various multimediatransmission schemes. However, many current cryptosystems tend to adopt a single-layer permutation ordiffusion algorithm, resulting in inadequate security. A hierarchical bilateral diffusion architecture for colorimage encryption is proposed in response to this issue, based on a hyperchaotic system and DNA sequenceoperation. Primarily, two hyperchaotic systems are adopted and combined with cipher matrixes generationalgorithm to overcome exhaustive attacks. Further, the proposed architecture involves designing pixelpermutation,pixel-diffusion, and DNA (deoxyribonucleic acid) based block-diffusion algorithm, consideringsystem security and transmission efficiency. The pixel-permutation aims to reduce the correlation of adjacentpixels and provide excellent initial conditions for subsequent diffusion procedures, while the diffusionarchitecture confuses the image matrix in a bilateral direction with ultra-low power consumption. The proposedsystem achieves preferable number of pixel change rate (NPCR) and unified average changing intensity (UACI)of 99.61% and 33.46%, and a lower encryption time of 3.30 seconds, which performs better than some currentimage encryption algorithms. The simulated results and security analysis demonstrate that the proposedmechanism can resist various potential attacks with comparatively low computational time consumption.

The effects of a summer reading program for migrant children in migrant schools: First-year results from a randomized experiment

Qian Guo,Young-Suk Grace Kim,Yan Liu,Yan Peng,WENKAI SUN,Yijie Wang,Li Yang 서울대학교 교육연구소 2021 Asia Pacific Education Review Vol.22 No.1

Thanks to urbanization, some developing countries have a large migrant population. Academic performance of migrant children is usually far from satisfactory, much to the concern of educators and legislators. Meanwhile, research has attested to the importance of reading skill development by the end of third grade for later academic achievement. Against this background, we evaluated the effects of providing self-selected, developmentally appropriate books on the reading performance and summer reading amount of students in migrant schools in China, employing a randomized controlled trial. The intervention program improved rising second-graders’ word reading scores and summer reading amount. It proved particularly beneficial to low-performing children and children from disadvantaged families. The findings have implications for improving the academic achievement of migrant children in migrant schools in China and similar developing countries, especially where parental support may not be expected for the academic development of children.

Responses of Antioxidant Enzyme Activity to Different Fertilizer and Soil Moisture Conditions in Relation to Cold Resistance in Zanthoxylum armatum

Jiangtao Fan,Jingyan Wang,Xianzhi Liu,Changping Zhao,Chaobing Zhou,Tasheen Saba,Jiaojiao Wu,Wenkai Hui,Wei Gong 한국원예학회 2022 원예과학기술지 Vol.40 No.3

Zanthoxylum armatum, known as green prickly ash, is a major condiment species planted on a large scale in southwest China. However, its limited cold tolerance has been a significant disadvantage for its cultivation in low-temperature regions. To better understand the antioxidant enzyme activities related to cold resistance, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities as well as malondialdehyde (MDA) content were investigated under 16 fertilizer and soil moisture treatments to explore the cold resistance response mechanism in Z. armatum. The results showed that low temperatures could significantly affect antioxidant enzyme activities in the leaves of Z. armatum seedlings. The antioxidant enzyme activities of seedlings treated with soil moisture and fertilizer treatments were significantly higher than those without fertilizer. Furthermore, the comprehensive evaluation index (CEI) was positively correlated with SOD, POD, and CAT activities but negatively correlated with MDA content. Meanwhile, the treatment T12 (60% field water capacity + 300 kg·ha-1 nitrogen + 30 kg·ha-1 phosphoric anhydride) had the highest CEI value, whereas T1 (20% water capacity) had the lowest. Based on the regression equation for CEI improvement, the predicted optimal levels for field water capacity (FWC), nitrogen, phosphorus, and potassium were 59.6%–63.4% FWC (average 61.5%), 114.2–248.8 kg N/ha (average 181.5 kg N/ha), 40.1–108.5 kg P2O5/ha (average 74.3 kg P2O5/ha), and 200.2–254.4 kg K2O/ha (average 227.3 kg K2O/ha), respectively. The present study provides the optimal soil moisture and fertilizer concentration required to enhance protective enzyme activity and low-temperature tolerance, which is crucial for improving cold resistance in Z. armatum.

Efficiency of gerAa, tupA and ca transformation in Bacillus subtilis for self-healing of concrete cracks

Hanxing He,Gefei Li,Jiantao Zhang,Jinlong Zhang,Mingyue Luo,Wenkai Hu,Yamin Lin,Ziyu Deng,Zhicheng Liu,Weizhao Chen,Xu Deng 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.5

A genetic approach was proposed to modify the characteristics of Bacillus subtilis strain WB800 (B. subtilis WB800) for selfhealing of concrete cracks. Three genes, namely gerAa which encodes germination receptors activated by L-alanine, tupA which is responsible for the synthesis of teichuronopeptide, and ca which encodes carbonic anhydrase (CA) catalyzing the synthesis of carbonate ion, were separately transformed into WB800. To protect bacterial cells from being squeezed, microspheres were produced with microcrystal cellulose (MCC) before the introduction of bacteria into the specimens. The results showed that the modified B. subtilis expressing GerA achieved 39.9% of germination ratio compared to 17% by the original host cells. With the transformation of tupA, the modified strain demonstrated higher resistance to alkaline environments, tolerating pH as high as 11, while the original strain only tolerated pH 9. The modified strain expressing CA induced more calcium carbonate than the original cells. Energy dispersive spectroscopy (EDS) identified the produced precipitate to be calcite (CaCO3). Moreover, a mathematical model was developed to optimize the influential factors of calcium precipitation process. Finally, based on the above results, an effective self-healing of concrete crack was achieved. This study may provide a promising strategy to improve the efficiency of bacterial self-healing of concrete cracks.

EpiLoc: Deep Camera Localization Under Epipolar Constraint

Luoyuan Xu,Tao Guan,Yawei Luo,Yuesong Wang,Zhuo Chen,WenKai Liu 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.6

Recent works have shown that the geometric constraint can be harnessed to boost the performance of CNN-based camera localization. However, the existing strategies are limited to imposing image-level constraint between pose pairs, which is weak and coarse-gained. In this paper, we introduce a pixel-level epipolar geometry constraint to vanilla localization framework without the ground-truth 3D information. Dubbed EpiLoc, our method establishes the geometric relationship between pixels in different images by utilizing the epipolar geometry thus forcing the network to regress more accurate poses. We also propose a variant called EpiSingle to cope with non-sequential training images, which can construct the epipolar geometry constraint based on a single image in a self-supervised manner. Extensive experiments on the public indoor 7Scenes and outdoor RobotCar datasets show that the proposed pixel-level constraint is valuable, and helps our EpiLoc achieve state-of-the-art results in the end-to-end camera localization task.