Research on Aero-engine Maneuvering Load Distribution Based on POT Model

Xuming Niu,Hongtao Liu,Cong Xu,Zhigang Sun,Yingdong Song,Qi Lu 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.3

The maneuvering load is significantly correlated with the pilot's operation, thus indicating the maneuvering motion of the aero-engine during the actual flight. Accordingly, the establishment of accurate distribution models is of great engineering significance and high theoretical value for the compilation of load spectrum. In this paper, to analyzing the statistics of the normal overload coefficient (NOC) spectrum of aero-engine, a mixed distribution model is built in accordance with the Peak Over Threshold (POT) model. A threshold selection method relating to usage is proposed based on the correlation between the rotating speed and the normal overload coefficient. The normal overload coefficient data which is higher than the threshold is defined as extreme load, while the normal overload coefficient data which is lower than the threshold is defined as medium–low load. The multi-correlation coefficient between the model fitting distribution curve and the measured normal overload coefficient distribution curve lays a basis for judging. As revealed by the results, the measured normal overload coefficient finds good agreement with the mixed distribution model.

Transition Mechanism from Brittle Fracture to Ductile Shear when Machining Brittle Materials with an Abrasive Waterjet

Chuanzhen Huang,Hongtao Zhu,Xinyu Lu,Quanlai Li,Cuilian Che 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.2

Critical erosion kinetic energy models for radial/median cracks and lateral cracks in a workpiece are established in this study. We used experimental results to demonstrate that the fracture erosion resistance and erosion machining number could be used to evaluate the brittle fracture resistance and machinability of a workpiece. Erosion kinetic energy models were developed to predict brittle fracture and ductile shear, and a critical erosion kinetic energy model was developed to predict the transition from brittle fracture to ductile shear. These models were verified experimentally.

The hydrogen storage nanomaterial MgH2 improves irradiation-induced male fertility impairment by suppressing oxidative stress

Jing Ma,Suhe Dong,Hongtao Lu,Zhongmin Chen,Huijie Yu,Xuejun Sun,Renjun Peng,Wei Li,Sinian Wang,Qisheng Jiang,Fengsheng Li,Li Ma 한국생체재료학회 2022 생체재료학회지 Vol.26 No.2

Objective: This study aimed to reveal the protective effect of hydrogen storage nanomaterial MgH2 on radiationinduced male fertility impairment. Methods: The characterization of MgH2 were analyzed by scanning electron microscopy (SEM) and particle size analyzer. The safety of MgH2 were evaluated in vivo and in vitro. The radioprotective effect of MgH2 on the reproductive system were analyzed in mice, including sperm quality, genetic effect, spermatogenesis, and hormone secretion. ESR, flow cytometry and western blotting assay were used to reveal the underlying mechanisms. Results: MgH2 had an irregular spherical morphology and a particle size of approximately 463.2 nm, and the content of Mg reached 71.46%. MgH2 was safe and nontoxic in mice and cells. After irradiation, MgH2 treatment significantly protected testicular structure, increased sperm density, improved sperm motility, reduced deformity rates, and reduced the genetic toxicity. Particularly, the sperm motility were consistent with those in MH mice and human semen samples. Furthermore, MgH2 treatment could maintain hormone secretion and testicular spermatogenesis, especially the generation of Sertoli cells, spermatogonia and round sperm cells. In vitro, MgH2 eliminated the [·OH], suppressed the irradiation-induced increase in ROS production, and effectively alleviated the increase in MDA contents. Moreover, MgH2 significantly ameliorated apoptosis in testes and cells and reversed the G2/M phase cell cycle arrest induced by irradiation. In addition, MgH2 inhibited the activation of radiation-induced inflammation and pyroptosis. Conclusion: MgH2 improved irradiation-induced male fertility impairment by eliminating hydroxyl free radicals.

Effects of In-Situ BaB6/Al Composite Inoculant on the Mechanical and Corrosion Behavior of Al–7Si–0.3Mg Alloy

Yingguang Liang,Chunxiang Cui,Hongtao Geng,Lu Liu,Sen Cui,Shichao Yang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4

In this work, as an inoculant, in-situ BaB6/Al composites was fabricated and used to refine the α-Al dendrites and modify theeutectic Si of A356.2(Al–7Si–0.3Mg) alloy. BaB6/Al ingot and ribbon composites mainly contain two phases, α-Al and BaB6. In BaB6/Al ribbons, nano-size BaB6ceramic particles exist and disperse uniformly which help to better exert the inoculanteffect in A356.2 alloy. YS, UTS, EL and HV of B2 alloy are 36.3%, 18.3%, 46.4% and 20.8% higher than the base alloy (B0),respectively. The ductile fracture characteristics are more obvious. Moreover, B2 alloy shows the best corrosion resistance. Aland BaB6form a clear, stable and well matched interface, so BaB6particles can act as the heterogeneous nucleation of α-Aland refine the A356.2 alloy. Furthermore, the combined of free micro-alloying elements Ba and B in BaB6/Al compositespromote the twins formation, which change the eutectic Si to fine fibrous and granular shape.

Shear-strain induced structural relaxation of Cu Σ3 [110](112) symmetric tilt grain boundary: The role of foreign atoms and temperature

Li Yang,Xue Hongtao,Zhou Xin,Tang Fuling,Li Xiuyan,Ren Junqiang,Lu Xuefeng 한국물리학회 2021 Current Applied Physics Vol.28 No.-

Grain boundaries (GBs) relaxation is a promising and effective strategy to improving GB stability or stabilizing nanocrystalline metals. However, previous studies mainly focused on nanocrystalline pure metals and GB behaviors therein, without considering the role of foreign atoms such as impurity or alloying atoms in GB relaxation. In this work, the shear-strain induced structural relaxation of pure Cu Σ3 [110](112) symmetric tilt GBs (STGBs), and the effects of foreign elements (Fe and Ni) and temperature on the GB relaxation were investigated in detail by molecular dynamics method. The results show that shear strain can trigger the structural relaxation of pure, Fe- and Ni-containing Cu GBs by the emission of Shockley partial dislocations from Cu GBs. Both Fe and Ni have impediment effects on the shear-strain induced GB relaxation, though the content of Fe or Ni atom (0.00165 at.%) is quite low in the GB model. The temperature cannot trigger GB relaxation independently within the considered temperature range, but play a positive role in the shear-strain induced structural relaxations of pure, Fe- and Ni-containing Cu Σ3 [110](112) STGBs. Our work might gain new insights into the mechanically induced GB relaxation in nanocrystalline copper and could be beneficial for improving the stability of Cu GBs.

Transition Mechanism from Brittle Fracture to Ductile Shear when Machining Brittle Materials with an Abrasive Waterjet

Huang, Chuanzhen,Zhu, Hongtao,Lu, Xinyu,Li, Quanlai,Che, Cuilian Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.2

Critical erosion kinetic energy models for radial/median cracks and lateral cracks in a workpiece are established in this study. We used experimental results to demonstrate that the fracture erosion resistance and erosion machining number could be used to evaluate the brittle fracture resistance and machinability of a workpiece. Erosion kinetic energy models were developed to predict brittle fracture and ductile shear, and a critical erosion kinetic energy model was developed to predict the transition from brittle fracture to ductile shear. These models were verified experimentally.

Performance optimization of flexible a-Si:H solar cells with nanotextured plasmonic substrate by tuning the thickness of oxide spacer layer

Xiao, Huapeng,Wang, Jun,Huang, Hongtao,Lu, Linfeng,Lin, Qingfeng,Fan, Zhiyong,Chen, Xiaoyuan,Jeong, Chaehwan,Zhu, Xufei,Li, Dongdong Elsevier 2015 Nano energy Vol.11 No.-

<P><B>Abstract</B></P> <P>Plasmonic thin film solar cells deposited on periodically textured photonic crystal substrates have been extensively studied since the substantially enhanced light absorption. The reduction of parasitic absorption losses in the metal and spacer layers becomes one of the key issues to achieve high efficiency solar cells. Herein, plasmonic amorphous silicon (a-Si:H) flexible thin film solar cells with different thickness of oxide spacer layers are systematically investigated. An increase of the spacer layer thickness leads to an evolution in surface morphology of AZO and final devices. More intriguingly, the increase of spacer layer thickness reduces the absorption in Ag layer while induces more absorption in spacer layer. The highest light absorption in silicon layer is observed as applying 100nm spacer layer, which is further verified by electrical measurements. Our observations demonstrate a versatile and convenient route towards rational design of light harvesting nanostructure for high performance plasmonic solar cells based on a broad range of materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amorphous silicon thin film solar cells are constructed on patterned substrates. </LI> <LI> The devices properties are studied as a function of spacer layer thickness. </LI> <LI> An increase of spacer layer thickness reduces the absorption loss of Ag layer. </LI> <LI> The device with 100nm spacer layer confines more incident light in silicon layer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Modeling and Implementation of Fixed Switching Frequency Sliding Mode Control to Two-Stage DC-DC Converter

Chang-hao Piao,Chao Jiang,Hongtao Qiao,조종두,Sheng Lu 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.6

A fixed switching frequency sliding mode (FSFSM) controller for two-stage DC-DC converter is proposed. Owing to the time-varying switched mode operation, the dynamic performance of two-stage converter becomes high order and non-linear. For designing the FSFSM controller, the state-space average model is made, and then the three conditions of sliding mode (SM) control, namely, hitting, existence and stability condition are analyzed. A conventional linear controller (Lag) for two-stage converter is designed as a comparison to validate the good robustness and dynamic response of the FSFSM controller. At last, a series of simulation and experimental results are presented to demonstrate the feasibility of the designed FSFSM controller.

Functional analysis of prv-miR-LLT11a encoded by pseudorabies virus

Huimin Liu,Li Yang,Zhibin Shi,Ruiqi Lv,Xia Yang,Chuanqing Wang,Lu Chen,Hongtao Chang 대한수의학회 2019 Journal of Veterinary Science Vol.20 No.6

Viral-encoded microRNAs (miRNAs) play have vital roles in the regulations of virus replications and host immune responses. The results of previous studies have indicated that miRNA clusters are involved in the replication and virulence of the pseudorabies virus (PRV), which may potentially lead to the immune escape or facilitation of PRV replications. This study's previous research revealed that the prv-mirmiR-LLT11a was differentially expressed during PRV infections. The present study's results have demonstrated that the prv-miR-LLT11a could significantly inhibit PRV replications. It was further determined that SLA-1 was the target gene of the prv-miR-LLT11a, and simultaneously, thate overexpression of prv-miR-LLT11a could down-regulate the mRNA and protein levels of SLA-1 in a dose-independent manner. Furthermore, the present study also found observed that the prv-miR-LLT11a canhad also down-regulated the TAP1 expressions. Our findings provide a better understanding of the molecular mechanism involved in on the effects of prv-miR-LLT11a on SLA-1 and TAP1, as well as and its involvement in a potential immune system evasion of PRV.