Distributed Control for Signed Networks of Nonlinear Agents

Mingjun Du,Baoli Ma,Deyuan Meng 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.2

This paper copes with distributed control problems for signed networks that consist of a group of nonlinear agents. A distributed control algorithm is designed by using the nearest neighbor rule. For Lipschitz-type nonlinear dynamics, this algorithm guarantees structurally balanced signed networks to achieve bipartite consensus and structurally unbalanced signed networks to reach state stability, respectively. When bounded nonlinear dynamics are considered, all agents exponentially converge to a definite bound within a finite time, regardless of whether the signed networks are structurally balanced or structurally unbalanced. A Lyapunov approach is simultaneously exploited to carry out the dynamic behaviors analysis of signed networks. Four examples are provided to demonstrate the validity of the developed theoretical results.

Distributed Optimization Algorithms on Structurally Balanced Signed Networks

Wen Du,Yusheng Wei,Mingjun Du 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

In this paper, we consider the distributed optimization problem under structurally balanced signed graph. First, we convert the original distributed optimization problem into a conditional minimum problem under the condition that the graph is structurally balanced. Our goal is to find the saddle points of augmented Lagrange function. Inspired by the Lagrange multiplier method, we present our algorithms for both undirected graph and digraph, and show that our algorithms asymptotically converge to the global minimizer. Particularly, our algorithms for digraph can not only handle the weight balanced case but the weight unbalanced case. We show that the unsigned graph is a special case of our signed graph cases. Finally, theoretical results are illustrated by numerical simulations.

The structural, electronic, elastic and optical properties of AlCu(Se1−xTex)2 compounds from first-principle calculations

Yongzhong Zhan,Mingjun Pang,Haizhou Wang,Yong Du 한국물리학회 2012 Current Applied Physics Vol.12 No.2

The structural, electronic structure, elastic and optical properties of the AlCu(Se1-xTex)2 compounds have been investigated by using a first-principles method based on density functional theory. The lattice constants of the quaternary compounds AlCu(Se1-xTex)2 increase with the increasing of Te composition. The calculated lattice constants for the ternary compounds i.e. AlCuSe2 and AlCuTe2 are in good agreement with the experimental data. The band structures show that the compounds have direct band gap and the band gaps are found to vary nonlinearly with composition. The total and part density of states of the quaternary AlCu(Se1-xTex)2 compounds are discussed. The calculated elastic constants indicate that all of the AlCu(Se1-xTex)2 compounds are mechanically stable. The bulk modulus B, shear modulus G,Young’s modulus E and Poisson’s ratio n can be obtained by using the VoigteReusseHill averaging scheme. The B/G ratios of the AlCu(Se1-xTex)2 compounds indicate that AlCu(Se0.8Te0.2)2 is ductile and the others are brittle. The Debye temperature of the AlCu(Se1-xTex)2 compounds decreases a little with increasing Te content except the compound with x¼ 0.4. The dielectric functions, refractive index,extinction coefficient, absorption spectrums and energy-loss function of the AlCuSe2 and AlCuTe2 are also calculated and discussed in this work. The structural, electronic structure, elastic and optical properties of the AlCu(Se1-xTex)2 compounds have been investigated by using a first-principles method based on density functional theory. The lattice constants of the quaternary compounds AlCu(Se1-xTex)2 increase with the increasing of Te composition. The calculated lattice constants for the ternary compounds i.e. AlCuSe2 and AlCuTe2 are in good agreement with the experimental data. The band structures show that the compounds have direct band gap and the band gaps are found to vary nonlinearly with composition. The total and part density of states of the quaternary AlCu(Se1-xTex)2 compounds are discussed. The calculated elastic constants indicate that all of the AlCu(Se1-xTex)2 compounds are mechanically stable. The bulk modulus B, shear modulus G,Young’s modulus E and Poisson’s ratio n can be obtained by using the VoigteReusseHill averaging scheme. The B/G ratios of the AlCu(Se1-xTex)2 compounds indicate that AlCu(Se0.8Te0.2)2 is ductile and the others are brittle. The Debye temperature of the AlCu(Se1-xTex)2 compounds decreases a little with increasing Te content except the compound with x¼ 0.4. The dielectric functions, refractive index,extinction coefficient, absorption spectrums and energy-loss function of the AlCuSe2 and AlCuTe2 are also calculated and discussed in this work.

Effects of vertebral number variations on carcass traits and genotyping of Vertnin candidate gene in Kazakh sheep

Zhang, Zhifeng,Sun, Yawei,Du, Wei,He, Sangang,Liu, Mingjun,Tian, Changyan Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.9

Objective: The vertebral number is associated with body length and carcass traits, which represents an economically important trait in farm animals. The variation of vertebral number has been observed in a few mammalian species. However, the variation of vertebral number and quantitative trait loci in sheep breeds have not been well addressed. Methods: In our investigation, the information including gender, age, carcass weight, carcass length and the number of thoracic and lumbar vertebrae from 624 China Kazakh sheep was collected. The effect of vertebral number variation on carcass weight and carcass length was estimated by general linear model. Further, the polymorphic sites of Vertnin (VRTN) gene were identified by sequencing, and the association of the genotype and vertebral number variation was analyzed by the one-way analysis of variance model. Results: The variation of thoracolumbar vertebrae number in Kazakh sheep (18 to 20) was smaller than that in Texel sheep (17 to 21). The individuals with 19 thoracolumbar vertebrae (T13L6) were dominant in Kazakh sheep (79.2%). The association study showed that the numbers of thoracolumbar vertebrae were positively correlated with the carcass length and carcass weight, statistically significant with carcass length. To investigate the association of thoracolumbar vertebrae number with VRTN gene, we genotyped the VRTN gene. A total of 9 polymorphic sites were detected and only a single nucleotide polymorphism (SNP) (rs426367238) was suggested to associate with thoracic vertebral number statistically. Conclusion: The variation of thoracolumbar vertebrae number positively associated with the carcass length and carcass weight, especially with the carcass length. VRTN gene polymorphism of the SNP (rs426367238) with significant effect on thoracic vertebral number could be as a candidate marker to further evaluate its role in influence of thoracolumbar vertebral number.

Study on stability of self-synchronous far-resonant vibrating system of two eccentric rotors considering material impact

Yongjun Hou,Guang Xiong,Pan Fang,Yuwen Wang,Mingjun Du 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

The self-synchronizing far-resonant vibrating system of two eccentric rotors is widely used in petroleum, mining and food industries, and its motion stability is affected by material impact. However, the synchronous characteristics and stability of this kind of the system are studied rarely. Based on the background, a simplified mechanical model of the selfsynchronous vibrating system driven by two eccentric rotors considering material impact is proposed. Firstly, the differential equations of motion about the system in non-collision and collision phase are established by using Lagrange equation and the theorem of momentum. Then, the section of Poincare maps and linearization matrix at the fixed point are solved. Finally, the dynamic behavior of material and system is analyzed, and then the change characteristics of the phase difference of the two eccentric rotors are revealed by numerical simulation. It can be concluded that the motion forms of the system and the rules of abrupt change about the phase difference evolve from periodic variation into chaotic state with the mass ratio of material to vibrating body increasing.

Study on synchronization characteristics for self-synchronous vibration system with dual-frequency and dual-motor excitation

Min Zou,Pan Fang,Huan Peng,Duyu Hou,Mingjun Du,Yongjun Hou 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In petroleum drilling engineering, drilling shakers are critical devices for cleansing solid particles and recycling drilling fluid. For the problem that the vibration screen with a single frequency usually results in flurry overflow due to the blocking of screen mesh, a selfsynchronous vibratory system with dual-frequency and dual-motor excitation is proposed. But it is not clear about the synchronization mechanism and dynamic characteristics of the system, which causes a lack of theoretical description for the source of synchronization phenomenon. Hence, this paper explores the synchronization mechanism and dynamic characteristics around the proposed system above. First, vibration and stability theory are employed to master the dynamic characteristics of the system, and the dynamic model is established by Lagrange equation. Then, displacement responses of the system are obtained by dimensionless formulas. Synchronous condition and synchronous stability between the unbalanced rotors are derived with small parameter method and Poincare method. Finally, some computer simulations are implemented to further verify the correctness of the theoretical analysis. The research result shows that the synchronous ability between the two unbalanced rotors actuated by dual-frequency excitation is related to the distance from the rotating center of the motor to the centroid of supporting body, and the greater the distance value, the better the synchronization of the vibrating system. This study will promote the recycle technology development of drilling fluid and settlement of the common scientific issues in vibrating synchronization.

Aggregation behavior analysis of hydrate particles in the bend pipe based on the population balance model

Cheng Yu,Lin Wang,Chuanjun Han,Jiaqiang Jing,Yuxing Li,Wuchang Wang,Mingjun Du,Xincan Song,Longyao Zhang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

The hydrate particle aggregation is crucial for the flow safety of oil and gas pipelines. In this paper, coupled with the Eulerian-Eulerian model, k-ε turbulence model and the population balance model considering the hydrate aggregation and breakage, the hydrate aggregation process is studied in the bend, and the change of the average particle size under different hydrate volume fractions is discussed. The results show that the hydrate aggregation process includes two stages in the bend, namely the rapid growth and the dynamic equilibrium. In the rapid growth stage, both the hydrate concentration and particle size in the elbow increase rapidly, and the high concentration and large particle size regions on the inside of the elbow also increase significantly. Furthermore, two types of aggregates are formed on the inside of the elbow. One is a small amount of large-particle aggregates, while the other is the relatively high concentration of medium-size aggregates. Besides, the uniform suspension with a smaller concentration and particle size is distributed on the outside of the elbow, but there are also large-size particles that aggregate and adhere near the wall of pipe. As the hydrate volume fraction increases, the hydrate average particle size increases. High concentration hydrate reaches dynamic equilibrium faster during the flow process.

Numerical simulation of hydrate slurry flow behaviors with micron-sized sand in the transport pipe based on the population balance model

Cheng Yu,Chuanjun Han,Lin Wang,Jiaqiang Jing,Yuxing Li,Wuchang Wang,Mingjun Du,Xincan Song 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

Both micron-sized sand particles flowing into the pipe and the secondary formation of natural gas hydrate will pose a great threat to the flow assurance of the pipeline for hydrate exploitation. Therefore, based on the population balance model considering the aggregation and breakage of hydrate and micron-sized sand particles, the flow characteristics coupling hydrate and micron-sized sand are studied, and the effects of flow velocity are discussed. The results show that the slurry viscosity increases significantly at the lower part of the horizontal pipe where the solid particles tend to aggregate. After the slurry enters the elbow pipe, the viscosity, hydrate concentration, and particle size gradually decrease, while the sand concentration first increases and then decreases. Solid particles with relatively high concentration and large particle size appear on the outside of the first half of the elbow. In the vertical pipe, the hydrate concentration and particle size gradually increase again, and the hydrate with high concentration and large particle size appears on the inside. Besides, the coupling aggregation of hydrate and sand particles is concentrated near the wall of the bottom of the horizontal pipe, near the wall of the outside of the elbow pipe and the inside of the second half of the elbow, and near the wall of the vertical pipe. The high flow velocity has a great ability to carry the hydrate with high concentration and large size.