Adaptive local approximation neural network control based on extraordinariness particle swarm optimization for robotic manipulators

Huayang Sai,Zhenbang Xu,Ce Xu,Xiaoming Wang,Kai Wang,Lin Zhu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3

In this paper, an adaptive radial basis function neural network (RBFNN) controller based on extraordinariness particle swarm optimization (EPSO) is proposed. To improve the trajectory tracking performance of robotic manipulators, the uncertainties of the manipulator dynamic equation are locally approximated using three RBFNNs with optimized hyperparameters. Besides, a robust control item is also considered in the controller to resist external disturbances. During hyperparameters optimization, the EPSO optimizer iteratively optimizes the hyperparameters of the RBFNN controller using the composite error of the system output. The stability of the control scheme is analyzed with the Lyapunov stability. Simulation results as well as the experimental verification prove the efficiency and applicability of the control scheme.

Compression Characteristics of Ultra-soft Clays Subjected to Simulated Staged Preloading

Huayang Lei,Xuechao Wang,Li Chen,Maosong Huang,Jie Han 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2

Ultra-soft soils have high water content, low strength, and high compressibility. Staged preloading has been commonly used in China to improve ultra-soft soils during land reclamation before highways and other structures are constructed. In this study, seven series of one-dimensional consolidation tests were performed on undisturbed, remolded, or reconstituted specimens of three types of soils subjected to simulated, staged loading. Test results showed that the compression curves had two straight lines, which intersected at a yield stress. Burland’s concept of the intrinsic compression line was adopted to present the compression curves of reconstituted clays at different initial water contents. The intrinsic compression line was modified to better fit the test data for the stresses lower than 40 kPa. The coefficient of soil consolidation increased with an increase of the effective vertical stress as a result of the rate of increase in constrained modulus higher than that of decrease in permeability. The maximum coefficient of secondary consolidation, Cámax, was correlated with the ratio of the initial void ratio to the void ratio at yield stress by a unique curve, which was proposed to distinguish the pre-yield stress from the post-yield stress state. Test results showed that the secondary compression characteristics depended on the applied stress and the initial void ratio.

Adaptive Nonsingular Fast Terminal Sliding Mode Impedance Control for Uncertainty Robotic Manipulators

Huayang Sai,Zhenbang Xu,Yi Li,Kai Wang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.12

This paper describes an impedance controller that uses the fast terminal sliding mode and adaptive neural networks. The proposed controller improves the dynamic trajectory performance and force tracking accuracy of robotic manipulators in three-dimensional uncertain environments. The key idea of the controller is that the improved adaptive nonsingular fast terminal sliding mode (ANFTSMC) uses integral control to eliminates chattering without affecting the tracking performance. Also, adaptive neural networks are introduced into the sliding mode controller to provide a local approximation in the dynamic model of the robotic manipulator, and the stability is guaranteed through the Lyapunov theory. Finally, combined with impedance control, the operation of the robotic manipulator is simulated in environments containing various obstacle types, and experimental validation has demonstrated the effectiveness and superiority of the proposed control scheme.

Scaling Inter-domain Routing System via Path Exploration Aggregation

( Xiaoqiang Wang ),( Peidong Zhu ),( Xicheng Lu ),( Kan Chen ),( Huayang Cao ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.3

One of the most important scalability issues facing the current Internet is the rapidly increasing rate of BGP updates (BGP churn), to which route flap and path exploration are the two major contributors. Current countermeasures would either cause severe reachability loss or delay BGP convergence, and are becoming less attractive for the rising concern about routing convergence as the prevalence of Internet-based real time applications. Based on the observation that highly active prefixes usually repeatedly explore very few as-paths during path exploration, we propose a router-level mechanism, Path Exploration Aggregation (PEA), to scale BGP without either causing prefix unreachable or slowing routing convergence. PEA performs aggregation on the transient paths explored by a highly active prefix, and propagates the aggregated path instead to reduce the updates caused by as-path changes. Moreover, in order to avoid the use of unstable routes, PEA purposely prolongs the aggregated path via as-path prepending to make it less preferred in the perspective of downstream routers. With the BGP traces obtained from RouteViews and RIPE-RIS projects, PEA can reduce BGP updates by up to 63.1%, shorten path exploration duration by up to 53.3%, and accelerate the convergence 7.39 seconds on average per routing event.

A Study on Wood Properties and Pulping Performance of Willow (Salix matsudana cv. Zhuliu)

Yu Liu,Tai Guo,Gui-HuaYang,Hui-Mei Wang 한국펄프·종이공학회 2016 한국펄프·종이공학회 학술발표논문집 Vol.2016 No.10

A Theoretical Study on the Mechanism of Decarboxylations for Hydroxymandelate Synthase

Qing-An Qiao,Qiuxian Li,Changchun Liu,Xiao Sun,Honglan Cai,Lixiang Sun,Huayang Wang 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.6

Hydroxymandelate synthase is one type of alpha-keto acid-dependent oxygenases and plays an important role in the biosynthesis of hydroxyphenyl-pyruvate. The ferrous and ferryl intermediates in the reaction were considered to be very important in the DNA repair process. The mechanism of hydroxymandelate synthase was investigated by a theoretical method based on B3LYP/LACVP*. The data indicated that each decarboxylation went through a process of direct dioxygen insertion. The first oxidative decarboxylation experienced only one transition state, while there were two potential pathways for the second decarboxylation process. The calculation data showed that the stepwise one was favored to the concerted one due to the lower energy barrier. The process to form the iron-superoxide was the rate-limiting step. After two consecutive decarboxylations, a proton transfer reaction was needed to obtain the target products. Two possible transition states were found out to achieve this step. The one with a six-membered ring structure was preferred because of the lower activation energy. In addition, several ferryl species with high spins were captured in the whole process, which could be supplied as requisite substrates for DNA repair reaction.

Core gut microbiota in Jinhua pigs and its correlation with strain, farm and weaning age

Hua Yang,Yingping Xiao,Junjun Wang,Yun Xiang,Yujie Gong,Xueting Wen,Defa Li 한국미생물학회 2018 The journal of microbiology Vol.56 No.5

Gut microbial diversity and the core microbiota of the Jinhua pig, which is a traditional, slow-growing Chinese breed with a high body-fat content, were examined from a total of 105 fecal samples collected from 6 groups of pigs at 3 weaning ages that originated from 2 strains and were raised on 3 different pig farms. The bacterial community was analyzed following high-throughput pyrosequencing of 16S rRNA genes, and the fecal concentrations of short-chain fatty acids (SCFAs) were measured by gas chromatograph. Our results showed that Firmicutes and Bacteroidetes were the dominant phyla, and Lactobacillus, Streptococcus, Clostridium, SMB53, and Bifidobacterium were the most abundant genera. Fifteen predominant genera present in every Jinhua pig sample constituted a phylogenetic core microbiota and included the probiotics Lactobacillus and Bifidobacterium, and the SCFAproducing bacteria Clostridium, Prevotella, Bacteroides, Coprococcus, Roseburia, Ruminococcus, Blautia, and Butyricicoccus. Comparisons of the microbiota compositions and SCFA concentrations across the 6 groups of pigs demonstrated that genetic background and weaning age affected the structure of the gut microbiota more significantly than the farm. The relative abundance of the core genera in the pigs, including Lactobacillus, Clostridium, Prevotella, Bacteroides, Roseburia, Ruminococcus, Blautia, and Butyricicoccus varied dramatically in pigs among the 2 origins and 3 weaning ages, while Oscillospira, Megasphaera, Parabacteroides, and Corynebacterium differed among pigs from different farms. Interestingly, there was a more significant influence of strain and weaning age than of rearing farm on the SCFA concentrations. Therefore, strain and weaning age appear to be the more important factors shaping the intestinal microbiome of pigs.