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Comparison of structural design and future trends in composite hulls: A regulatory review
Han Zhiqiang,장재원,Souppez Jean-Baptiste R.G.,서형석,오대균 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-
Recently, the International Organization for Standardization (ISO) standards associated with composite hullstructure design, including the method for estimating the mechanical properties of laminates necessary for design, have been revised. This study reviews the revisions concerning materials and analyzes the design trend of composite hull structures by comparing eight related rules, including classification society and domestic rules. The results reveal that the current design trend of hull laminates is to thoroughly consider the impact of several variables, including the weight fraction of reinforcement (glass content; Gc), fabric combination, and fabrication method, on the laminate properties. For illustration, these effects were verified with a typical glass-fiberreinforced plastic vessel based on a case study, the experimental results of extant studies, and current standards. The industry design conditions, normal Gc (0.367) and high Gc (0.600), were selected and applied to two fabric combinations: chopped strand mat and chopped strand–woven roving. The hull laminate design results based on the revised ISO standards (ISO 12215) satisfied the safety and weight requirements for normal Gc in both cases. This may be attributed to the high mechanical properties suggested in the current standards regardless of how they reflect the effects of changes in fabric type, combination, and method on the mechanical properties of the laminates. For high Gc, the combination material case satisfied the safety requirements to a greater extent. and this can also be made lightweight. In contrast, the single material case based on the revised ISO standard may result in safety issues, mainly because the revised ISO standard reflects the adverse effects of design variables such as Gc and fabric blends on the laminate fabrication quality. Further, non-ISO rules should be revised in the future to reflect the effects of each variable in the material design according to the research trends of composite materials.
Zhiqiang Han,Gang Han,Zhiyong Wang,Bonian Shui,Tianxiang Gao 한국유전학회 2015 Genes & Genomics Vol.37 No.5
Amplified fragment length polymorphism markers were used to estimate the genetic divergence and genetic structure of Lateolabrax maculatus, L. japonicus and their possible hybrid populations in the Northwestern Pacific. Ninety one individuals were sampled from nine localities including two putative hybrid samples across the distribution range of the two species. Five primer combinations generated a total of 423 loci among 91 individuals of L. maculatus and L. japonicus, 266 of which were polymorphic (62.88 %). The percentage of polymorphic loci in three populations of L. maculatus and five populations of L. japonicus ranged from 31.96 % (Beihai) to 37.94 % (Weihai), 31.05 % (Ishikawa) to 49.29 % (Yatsushiro Sea), respectively. The UPGMA tree constructed with individuals of both species indicated reciprocal monophyletic relationship between L. japonicus and L. maculatus. Hybrid individuals between the two species in Ariake Sea and Yatsushiro Sea were identified by UPGMA tree and principal component analysis (PCA). The sympatry of two clades in the Yatsushiro Sea gave the first evidence of possible reproductive isolation between hybrid and L. japonicus. AMOVA analysis and pairwise FST revealed significant genetic differentiation within both species, indicating limited dispersal ability in two species. Historical isolation coupled with low dispersal ability was responsible for the genetic divergence between species and significant genetic structure in the two species.
A Hybrid Public Opinion Analysis Method Based on Improved Clustering and Mutual Information
Zhiqiang Geng,Xia Tang,Yikang Zhang,Yongming Han 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.3
The Internet is frequently used as a medium for exchange of information and opinions, and it is imperative to conduct public opinion analysis to get people’s opinions well understood and guided. In this paper a hybrid public opinion analysis method based on improved clustering and mutual information is proposed. During feature extraction, the weights of words are modified based on Part-of-Speech Tagging to reduce the dimensions of original texts. As for clustering, a novel density peak algorithm is improved and combined with binary search algorithm to determine the cluster number K and initial centers for KMeans. Then hot words extraction, sentiment analysis and trend analysis for each cluster are processed with mutual information to mine useful knowledge to help decision-making. Extensive experiments are conducted on Hadoop, and the results show that our hybrid Public Opinion Analysis method is quite effective and has certain significance.
Zhiqiang Liu,Ming Chen,Jinyang Xu,Shu Han 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
This paper presents a new flexible method referring to coupling response surface methodology (CRSM) to acquire optimum cutting parameters in machining of difficult-to-cut titanium alloy under minimum quantity lubrication (MQL) condition. Cutting speed, feed rate and depth of cut are designed as three factors by using the Taguchi method, which are also subject to several constraints including processing efficiency, cutting force and surface quality. In addition, turning experiments of titanium alloy were performed in order to set up the model based on Taguchi experimental design and multiple regression method. ANOVA was carried out to prove the adequacy of the developed mathematical model and the influences of cutting parameters on constraints were also observed. The results indicated that the feed rate was the dominant factor affecting surface roughness and cutting forces, which were minimized when the feed rate and depth of cut were set to the lowest level, while cutting speed was set to the highest level. Moreover, the predicted values obtained by CRSM were in good agreement with the experimental values, which indicated that CRSM was an effective method to determine optimum cutting conditions for machining process under MQL condition.
GFRP 낚시어선의 선체구조 적층판 분석과 경량화 설계
장재원,Zhiqiang Han,오대균 한국해양공학회 2019 韓國海洋工學會誌 Vol.33 No.6
Approximately 90,000 ships are registered in South Korea, and about 80,000 of these ships are used in domestic shipping. Among these, 84% are small ships, such as a fishing vessels that weigh less than 20 tons and are made mostly of an FRP (Fiber Reinforced Plastics). When this fact is taken into account, the greenhouse gas emissions that are released per ton of a composite vessel are sizeable. In this study, the laminated structures of an FRP fishing vessel, many of which currently are being built in Korea, were analyzed by ISO (International Organization for Standardization) and international design rules, and the structures of the hulls are lightweight with optimum glass fiber mass content as determined by the laminate weight minimization algorithm. As a result, it was confirmed that the laminations of the vessels in accordance with the Korean rule could have 6.4% to approximately 11% more design margin compared to the requirements of ISO and other international rules. And the case study of the application of the laminate weight minimization algorithm showed the possibility of reducing the weight of the hull bottom plating by as much as about 19.32% and by as much as about 18.06% in the overall structure.