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Power extraction performance of two semi-active flapping airfoils at biplane configuration
Jianyang Zhu,Jiacheng Zhang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1
The power extraction performance of two semi-active flapping airfoils at biplane configuration is analyzed in this work through numerical approach. Two NACA0015 airfoils, which are regarded as an energy extraction turbine, are arranged in a biplane configuration to perform forced counter pitching motion and are subsequently induced in a plunging motion. A numerical code based on finite volume method to solve the Navier–Stokes equations coupled with finite center difference method to solve the passive plunging motion governing equation is developed to simulate the interaction between the two semi-active flapping airfoils and fluid. Results show that the semi-active flapping airfoil cannot absorb more power from the fluid with biplane arrangement, but this arrangement is beneficial for the power extraction efficiency of the airfoil. Analysis of the fluid field of the airfoil reveals that the wing–wing interaction can promote the vortex evolution and reduce the vortex magnitude of the suction side of the biplane airfoils with appropriate initial distance (h s = 2.5d). As a result, the maximum plunging of the biplane airfoils is smaller than that of the single airfoil. The smaller maximum plunging displacement contributes to the increase in power extraction efficiency.
Jingyu Zhang,Jiacheng Zhu,Shurong Ding,Liang Chen,Wenjie Li,Hua Pang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.7
Delayed hydride cracking (DHC) is an important failure mechanism for Zircaloy tubes in the demandingenvironment of nuclear reactors. The threshold stress intensity factor, KIH, and critical hydride length, lC ,are important parameters to evaluate DHC. Theoretical models of them are developed for Zircaloy tubesundergoing non-homogenous temperature loading, with new stress distributions ahead of the crack tipand thermal stresses involved. A new stress distribution in the plastic zone ahead of the crack tip isproposed according to the fracture mechanics theory of second-order estimate of plastic zone size. Thedeveloped models with fewer fitting parameters are validated with the experimental results for KIH andlC. The research results for radial cracking cases indicate that a better agreement for KIH can be achieved;the negative axial thermal stresses can lessen KIH and enlarge the critical hydride length, so its effectshould be considered in the safety evaluation and constraint design for fuel rods; the critical hydridelength lC changes slightly in a certain range of stress intensity factors, which interprets the phenomenonthat the DHC velocity varies slowly in the steady crack growth stage. Besides, the sensitivity analysis ofmodel parameters demonstrates that an increase in yield strength of zircaloy will result in a decrease inthe critical hydride length lC , and KIH will firstly decrease and then have a trend to increase with the yieldstrength of Zircaloy; higher fracture strength of hydrided zircaloy will lead to very high values ofthreshold stress intensity factor and critical hydride length at higher temperatures, which might be themain mechanism of crack arrest for some Zircaloy materials
ZhiKai Wang,ZhuMu Fu,ZiHao Wu,ChenQi Zhu,JiaCheng Li 한국항공우주학회 2024 International Journal of Aeronautical and Space Sc Vol.25 No.2
This paper presents a novel three-dimensional time-space cooperative guidance law against maneuvering target despite the presence of time-varying communication delays between missiles. The guidance law is divided into two parts. In the first part, a consensus protocol is designed for a multi-agent system consisting of a virtual leader and multiple followers. The objective is to tackle the problem of consensus convergence among the agents with communication delays. Additionally, the relationship between the upper bound of delays and the controller parameters is established. Based on the consensus protocol and a prescribed-time slide mode control method, the guidance law in the line-of-sight (LOS) direction is designed to ensure that the missiles attack the target simultaneously. In the second part, the multi-missile surrounding attack is achieved by designing different desired LOS azimuth and elevation angles for each missile. A guidance law in the normal LOS direction is designed based on the prescribed-time slide mode control method to ensure that the LOS angle converges to the desired values. To estimate the disturbances caused by the unknown and unpredictable acceleration of the maneuvering target in the LOS and normal LOS directions, fixed-time disturbance observers are designed. The stability analysis of the cooperative guidance law is provided in the appendix section. To demonstrate the effectiveness and superiority of the proposed cooperative guidance law, comparative simulations are performed.
Daojie Wang,Cuiling Yang,Long Dong,Jiacheng Zhu,Jianping Wang,Shufeng Zhang 한국식물학회 2015 Journal of Plant Biology Vol.58 No.4
Brassica napus is a dicotyledonous plant in the family Brassicaceae. It is an important oil crop which has been widely cultivated over the world. However, drought stress is a very important threatening to B. napus production. In this study, two B. napus strains with different resistance to drought stress were treated with 200 g/L PEG-6000 as drought simulation agent (marked as S, R)and two controls were treated with 1/2 Hoagland medium(marked as ST, RT). With the help of Illumina paired-end RNA-seq technology and de novo assembly by Trinity, we obtained 107,294 Unigenes (integrated four sample results) with an average length of 834 bp and N50 1245. Of these Unigenes, 84,768, 92,545, 54,857, 28,129, 75,278 were assigned to NR, NT, Swiss-Prot, COG and GO database respectively. A total of 46,861 were mapped to 128 pathways by BLAST comparison against the KEGG database. In order to have an overall understanding of the unique genes’ expression difference among four samples, we utilized RPKM to calculate Unigene expression, and to identify differentially expressed genes. Besides, 22,414 SSRs were developed in this study.
Xuyang Zhang,Hangjia Shen,Babak Rezaei Moghadam,Siqi Liu,Yuejin Zhu,Jiacheng Wang,Minghui Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.7
Practical application of oxygen evolution reaction (OER) in energy conversion devices, such as water splitting and metal-air batteries, relies on the development of highly efficient and stable electrocatalysts and is still challengeable. Here, Nickel modulated ternary Iron tungsten nitride (Ni-FeWN2) nanosheets are synthesized through a facile hydrothermal growth method and subsequently nitriding process for boosting OER. A potential of 1.57V at the current density of 10 mA/cm2 and Tafel slope (40 mV/dec) are achieved on Ni-FeWN2, much lower than that on Ni-free FeWN2 and commercial IrO2. More importantly, Ni-FeWN2 nanosheets display high stability and electrocatalytic activity toward driving oxygen evolution efficiently in alkaline media.