Damage Mechanisms and Metallic Materials Development in Multiphase Flow

Zheng, Yugui,Liu, Wei,Yao, Zhiming,Ke, Wei 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.1

The investigation on the synergistic effects among corrosion, slurry erosion and cavitation erosion has special significance for hydraulic turbines operated in Yangtze River and Yellow River where the high concentration solid particles exist in water. Two typical metallic materials i.e. Cr-Mn-N stainless steel and Ni-Ti shapememory-alloy, and two typical materials used for hydraulic turbines 20SiMn and 0Crl3Ni5Mo as compared materials were selected in order to investigate the roles ofwork-hardening ability and martensitic transformation as well as pseudoelastics in damage mechanism in rnultiphase flow. Both modified rotating disk rig and ultrasonic vibration facility were used to simulate the possible damage mechanism of materials in multiphase flow. The effects of corrosion on cavitation erosion were investigated through adding 3wt% NaCI. The degradation mechanism was analyzed by electrochemical test, SEM observation, hardness and roughness measurement. The results showed that there was a strong synergistic interaction among electrochemical corrosion, slurry erosion and cavitation erosion for 20SiMn in liquid-solid two-phase medium. In contrast, corrosion played little role for OCrl3NiSMo. Cr-Mn-N stainless steel with high Mn content showed better resistance to cavitation erosion and slurry erosion than 0Crl3NiSM0, which was mainly due to its good work-hardening ability as well as strain-induced martensite transformation. The cavitation micro-cracks for Cr-Mn-N stainless steel were parallel to the specimen surface in contrast with OCr13NiSMo whose micro-cracks were perpendicular to the surface. Ni-TI alloy with pseudoelasticity showed excellent resistance to combined interaction of cavitation erosion and slurry erosion.

Ovarian transcriptomic analysis of Shan Ma ducks at peak and late stages of egg production

Zhu, ZhiMing,Miao, ZhongWei,Chen, HongPing,Xin, QingWu,Li, Li,Lin, RuLong,Huang, QinLou,Zheng, NenZhu Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.9

Objective: To assess the differences in ovarian transcriptomes in Shan Ma ducks between their peak and late stages of egg production, and to obtain new transcriptomic data of these egg-producing ducks. Methods: The Illumina HiSeq 2000 system was used for high throughput sequencing of ovarian transcriptomes from Shan Ma ducks at their peak or late stages of egg production. Results: Greater than 93% of the sequencing data had a base quality score (Q score) that was not less than 20 (Q20). From ducks at their peak stage of egg production, 42,782,676 reads were obtained, with 4,307,499,083 bp sequenced. From ducks at their late stage of egg production, 45,316,166 reads were obtained, with 4,562,063,363 bp sequenced. A comparison of the two datasets identified 2,002 differentially expressed genes, with 790 upregulated and 1,212 downregulated. Further analysis showed that 1,645 of the 2,002 differentially expressed genes were annotated in the non-redundant (NR) database, with 646 upregulated and 999 downregulated. Among the differentially expressed genes with annotations in the NR database, 696 genes were functionally annotated in the clusters of orthologous groups of proteins database, involving 25 functional categories. One thousand two hundred four of the differentially expressed genes with annotations in the NR database were functionally annotated in the gene ontology (GO) database, and could be divided into three domains and 56 categories. The three domains were cellular component, molecular function, and biological process. Among the genes identified in the GO database, 451 are involved in development and reproduction. Analysis of the differentially expressed genes with annotations in the NR database against the Kyoto encyclopedia of genes and genomes database revealed that 446 of the genes could be assigned to 175 metabolic pathways, of which the peroxisome proliferator-activated receptor signaling pathway, insulin signaling pathway, fructose and mannose metabolic pathways, gonadotropin releasing hormone signaling pathway and transforming growth factor beta signaling pathway were significantly enriched. Conclusion: The differences in ovarian transcriptomes in Shan Ma ducks between their peak and late stages of egg production were elucidated, which greatly enriched the ovarian transcriptomic information of egg-producing ducks.

Quantized Sliding Mode H ∞ Control for Singular Markovian Jump Systems with Sensor Failure and Randomly Changing Structure

Wei Zheng,Zhiming Zhang,Hong-Bin Wang,Ming-Quan Zhang 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.12

The H∞ sliding mode control is studied for a class of singular Markovian jump systems with sensor failure, incompleted transition probabilities and randomly changing structure. A quantized input sliding mode controller is designed to deal with the sensor failure and time-varying delay. A new sliding mode surface and a new Lyapunov function are constructed to achieve the system stable and reduce the effect of the jumping mode. Based on the linear matrix inequalities (LMIs) theory, some sufficient conditions are derived to guarantee stochastically admissible with performance γ. The sliding mode reachability is also guaranteed. Simulation results are given to illustrate the effectiveness of the proposed method in this paper.

Visible-Light-Driven Catalytic Disinfection of Staphylococcus aureus Using Sandwich Structure g-C₃N₄/ZnO/Stellerite Hybrid Photocatalyst

( Wanzhong Zhang ),( Caihong Yu ),( Zhiming Sun ),( Shuilin Zheng ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.6

A novel g-C₃N₄/ZnO/stellerite (CNZOS) hybrid photocatalyst, which was synthesized by coupled hydro thermal-thermal polymerization processing, was applied as an efficient visiblelight-driven photocatalyst against Staphylococcus aureus. The optimum synthesized hybrid photocatalyst showed a sandwich structure morphology with layered g-C₃N₄ (doping amount: 40 wt%) deposited onto micron-sized ZnO/stellerite particles (ZnO average diameter: ~18 nm). It had a narrowing band gap (2.48 eV) and enlarged specific surface area (23.05 ㎡/g). The semiconductor heterojunction effect from ZnO to g-C₃N₄ leads to intensive absorption of the visible region and rapid separation of the photogenerated electron-hole pairs. In this study, CNZOS showed better photocatalytic disinfection efficiency than g-C₃N₄/ZnO powders. The disinfection mechanism was systematically investigated by scavengerquenching methods, indicating the important role of H₂O₂ in both systems. Furthermore, h⁺ was demonstrated as another important radical in oxidative inactivation of the CNZOS system. In respect of the great disinfection efficiency and practicability, the CNZOS heterojunction photocatalyst may offer many disinfection applications.

An Efficient Chaotic Image Encryption Algorithm Based on Self-adaptive Model and Feedback Mechanism

( Xiao Zhang ),( Chengqi Wang ),( Zhiming Zheng ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3

In recent years, image encryption algorithms have been developed rapidly in order to ensure the security of image transmission. With the assistance of our previous work, this paper proposes a novel chaotic image encryption algorithm based on self-adaptive model and feedback mechanism to enhance the security and improve the efficiency. Different from other existing methods where the permutation is performed by the self-adaptive model, the initial values of iteration are generated in a novel way to make the distribution of initial values more uniform. Unlike the other schemes which is on the strength of the feedback mechanism in the stage of diffusion, the piecewise linear chaotic map is first introduced to produce the intermediate values for the sake of resisting the differential attack. The security and efficiency analysis has been performed. We measure our scheme through comprehensive simulations, considering key sensitivity, key space, encryption speed, and resistance to common attacks, especially differential attack.

Effect of Externality in Multiplex Networks on One-layer Synchronization

Xin Jiang,Meng Li,Zhiming Zheng,Yifang Ma,Lili Ma 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.11

Synchronization phenomenon plays an important role in the dynamic process on complex networks. In this letter, we consider synchronization under multiplex structures and explore the effect of external parts on the multilayered Kuramoto model with positive correlation between frequencies and degree. We show that large and strong mixing parts of the external layer may put off synchronization while the coupling strength of external layers has an accelerating, but limited, influence on synchronization. In particular, an explosive synchronization can be obtained by weakening the co-evolution coupling strength. The transition tends to be smooth when the co-evolution coupling strength increases. Our findings indicate that externality from multiplex networks, especially the mixing parts, and the co-evolution coupling strength should be of importance for synchronization on one certain layer.

Evolutionary Dynamics of the Weighted Voter Model with Opinion Strength on Complex Networks

Shaoting Tang,Shu Yan,Sen Pei,Zhiming Zheng 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.11

The voter model has served to address the emergence of consensus within populations of individuals. However, the dynamics based on the classic voter model has usually been analyzed based on the assumption that the two states in the model are simply equivalent. In this paper, we discuss a mathematical description of the weighted voter model and obtain a series of results for the evolutionary process on complex networks. For homogeneous networks, we study the active link density analytically and find that the opinion strength plays a crucial role in determining whether the system can reach consensus. We also extend our research to heterogeneous networks and discover that the network structure can affect the convergence time but has less influence on the positive proportion. The results can be applied to various pervasive cases in which two conflicting opinions interact with each other.

An Improved Weight Optimization AAIM Method Aided by Barometric Altimeter

Xiaowei Xu,Jizhou Lai,Min Liu,Zhiming Zheng,Yuting Dai,Kai Huang 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.3

Aiming at the problem of insufficient availability in the satellite receiver autonomous integrity monitoring (RAIM) method, an improved aircraft autonomous integrity monitoring (AAIM) method aided by barometric altimeter based on weight optimization is proposed under the actual configuration of the airborne navigation system. The information of satellite navigation system and barometric altimeter is used to establish the observation equation of the integrated system. The algorithm for integrity monitoring and protection-level calculation is derived based on multiple solution separation, and a weight optimization is adopted to achieve a trade-off between position accuracy and integrity, which can improve the availability of AAIM method. The simulation experiment shows that when the number of visible stars is 5, the traditional method cannot effectively detect the satellite fault, and the positioning error is 43.65 m. The improved algorithm can effectively isolate the fault and reduce the positioning error to 0.37 m. Compared with the traditional RAIM algorithm and the Baro-aided AAIM algorithm, the proposed algorithm has a lower vertical protection threshold. Therefore, the algorithm in this paper improves the performance of satellite navigation system integrity monitoring and ensure the accuracy and reliability of the satellite navigation system.

CNC tool path generation for freeform surface machining based on preferred feed direction field

Guanying Huo,Xin Jiang,Cheng Su,Zehong Lu,Yuwen Sun,Zhiming Zheng,Deyi Xue 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.5

This paper presents a novel method to generate three-axis CNC tool paths for machining freeform surfaces based on a preferred feed direction field. This research was initiated from a fluid dynamics behavior that the energy loss can be reduced when the streamlines of fluid and the small grooves on a surface are in the same directions. In this research, the fluid streamlines above the surface are defined by a collection of vectors. These vectors are regularized into a grid of vectors, and these regularized vectors are further projected onto the tangent planes of a grid of points on the surface to create the preferred feed direction field. Based on the parametric model of the surface, the vectors on the tangent planes of the surface are mapped into vectors in the parametric domain. A scalar function is constructed such that the isolines of this scalar function and the preferred feed direction vectors in the parametric domain are in the same directions. A group of isolines of the scalar function are identified and these isolines are mapped back onto the 3-D surface as the created tool paths considering the tolerance requirement. The developed method has been applied to generate the tool paths for machining surfaces of a compressor blade.

Low-voltage blue light emission from n-ZnO/p-GaN heterojunction formed by RF magnetron sputtering method

Yanwei Shen,Xiang Chen,Xiaoqin Yan,Fang Yi,Zhiming Bai,Xin Zheng,Pei Lin,Yue Zhang 한국물리학회 2014 Current Applied Physics Vol.14 No.3

High quality n-ZnO/p-GaN heterojunction was fabricated by growing highly crystalline ZnO epitaxial films on commercial p-type GaN substrates via radio frequency (RF) magnetron sputtering. Low-voltage blue light emitting diode with a turn-on voltage of w2.5 V from the n-ZnO/p-GaN heterojunction was demonstrated. The diode gives a bright blue light emission located at w460 nm and a low threshold voltage of 2.7 V for emission. Based on the results of the photoluminescence (PL) and electroluminescence (EL) spectra, the origins of the EL emissions were studied in the light of energy band diagrams of ZnOeGaN heterojunction, and may attribute to the radiative recombination of the holes in p-GaN and the electrons injected from n-ZnO, which almost happened on the side of p-GaN layer. These results may have important implications for developing short wavelength optoelectronic devices.