Research on Nonlinear Vibration Characteristics of Spiral Bevel Gear

Nie Junfeng,Yu Guangbin,Song Ye,Qu Zhigang,Zheng Minli,Zhao Xingfu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.2

Based on the concentrated parameters theory, a 7-freedom coupled vibration dynamic model of the spiral bevel gear transmission system is established, which includes transmission error, time-varying mesh stiffness and the tooth backlash clearance. In the model, the axial vibration, the torsion oscillation of the gear pair aroused by tooth meshing force and the lateral oscillations resulting from flexional deformation of the gear shaft are taken into account. The mesh stiffness fluctuation is developed as 5-order Fourier series and the tooth backlash clearance is fitted by 7-order polynomial function. Through the Gear method, the dynamic response of the system is obtained, and the vibration characteristics are analyzed.

Chemical vapor deposition growth of large-scale hexagonal boron nitride with controllable orientation

Song, X.,Gao, J.,Nie, Y.,Gao, T.,Sun, J.,Ma, D.,Li, Q.,Chen, Y.,Jin, C.,Bachmatiuk, A. Springer Science + Business Media 2015 NANO RESEARCH Vol.8 No.10

Study on the Influence and Difference of Taijiquan and Five-animal Exercises on College Students' Ankle Muscle Strength

Nie, ShangQi,Ma, Biao,Song, Jeho The International Promotion Agency of Culture Tech 2020 International Journal of Advanced Culture Technolo Vol.8 No.3

The physique and health status of Chinese college students have received a generous concern in recent years. The physical condition of Chinese college students is not good and this phenomenon is especially obvious among female college students, which has been an disputable fact. This study starts from exercise intervention to study the concrete influence of taijiquan (a kind of traditional Chinese shadow boxing) and five-animal exercises on human body balance ability; the study uses experimental apparatus to measure the specific impact of exercise intervention on human body balance ability; meanwhile, the study also applies data analysis to longitudinally study whether the two studied sports items affect body balance, and whether there is difference in terms of the influence of two sports items on human body balance ability. The conclusions are as follows: firstly, 24-style taijiquan and five-animal exercises can improve ankle muscle strength, and the focus and degree of the improvement are different; secondly, five-animal exercises have a better improvement effect on the flexor and extensor muscles of ankle joint and 24-style taijiquan is in the second place. Moreover, compared with 24-style taijiquan, there is no significant difference in terms of the improvement caused by five-animal exercises; thirdly, 24-style taijiquan has a better effect on the improvement of internal rotation and evertors muscle strength. Compared with 24-style taijiquan, five-animal exercises have no significant difference in terms of the improvement degree.

Dynamic Characteristic Simulation of Helicopter Tail Drive Shaft System

Nie Junfeng,Yu Guangbin,Song Ye,Qu Zhigang,Zheng Minli,Zhao Xingfu 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.6

Helicopter with the advantage of light, flexible and hovering in the air, is widely used. In both military and civilian domain, it gets more and more attention. It becomes the main subject of research in the world. In the power transmission system of helicopter, the tail rotor shaft is an important part. It is one of the key technologies to predict the dynamic characteristics of the shaft accurately for improving the overall performance of the helicopter. Based on the theory of elastic mechanics, rotor dynamics and the finite element analysis, the former main drive shaft is taken as an example. The dynamic characteristics of the transmission shaft is calculated by the multi/few degrees of freedom finite element method. The validity of the finite element method with few degrees of freedom is determined. Then the structure characteristics of the helicopter tail drive shaft are analyzed, and the dynamic characteristics of the helicopter tail rotor shaft are calculated by using the finite element method with few degrees of freedom. The research results provide the basis and guidance for the design of the helicopter tail drive system.

Impact of sugarcane bagasse-derived biochar on heavy metal availability and microbial activity: A field study

Nie, Chengrong,Yang, Xing,Niazi, Nabeel Khan,Xu, Xiaoya,Wen, Yuhui,Rinklebe, Jö,rg,Ok, Yong Sik,Xu, Song,Wang, Hailong Elsevier 2018 CHEMOSPHERE - Vol.200 No.-

<P><B>Abstract</B></P> <P>In the current study, we conducted a field experiment using the test plant, <I>Brassica chinesis</I> L. (pak choi), to investigate the effect of sugarcane bagasse-derived biochar on the bioavailability of cadmium (Cd), copper (Cu) and lead (Pb), and the health of soil microbiota in a contaminated soil. Biochar application significantly (<I>P</I> < 0.05) increased pak choi yield. Bioavailability of heavy metals to plant shoots and roots decreased with increasing biochar application rates (at 0, 1.5, 2.25 and 3.0 t ha<SUP>−1</SUP>). Sequential extraction of the biochar-treated and -untreated soil revealed that exchangeable Cd reduced whereas organically-bound fraction increased with increasing biochar rate. The labile fractions of Cu and Pb decreased, but the residual fraction increased in biochar-treated soils compared to the control. Urease, catalase and invertase activities, and the populations of bacteria and actinomycetes were significantly enhanced, whereas fungi population declined in biochar-treated soils. This study highlights that sugarcane bagasse biochar has the potential to support the remediation of soils contaminated with heavy metals, and as such can improve the yield and quality of agricultural crops.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sugarcane bagasse biochar amendment reduced availability of Cd, Cu and Pb in soils. </LI> <LI> Heavy metals were less labile in the biochar-treated soils. </LI> <LI> Biochar amendment induced an increase in soil enzyme and microbial activity. </LI> <LI> Edible part of pak choi was safer for human consumption after biochar amendment. </LI> </UL> </P>

An efficient approach to fabricate lightweight polyimide/aramid sponge with excellent heat insulation and sound absorption performance

Shunxi Song,Yujie Shi,Jiaojun Tan,Zeshi Wu,Meiyun Zhang,Sheng Qiang,Jingyi Nie,Haitang Liu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.109 No.-

Polyimide sponges have bright prospects in the weight reduction, heat insulation, and sound absorptionequipment of aerospace, navigation, and other area due to their unique three-dimensional cellular structureand outstanding comprehensive performance. However, most polyimide sponges suffered from longand complex fabrication processes. Herein, an efficient and scalable approach, i.e. water-based foamforming, was proposed to fabricate ultralight and porous polyimide/aramid sponges (PASG). Attributedto the bubble-template nature of foam-forming, PASGs exhibit high porosity (>99%) and ultra-low density(10 mg/cm3), and possess excellent thermal and sound insulation performance with an optimum thermalconductivity of 34.89 mW/mK and noise reduction coefficient of 0.41. Besides, PASGs demonstrateoutstanding mechanical properties after 500 compression cycles. This strategy providing more possibilitiesfor developing the next generation of high-performance thermal insulation and noise reductionmaterials.

Circuit Model for the Effect of Nonradiative Recombination in a High-Speed Distributed-Feedback Laser

Bowen Nie,Zhijuan Chi,Qing-an Ding,Xiang Li,Changqing Liu,Xiaojuan Wang,Lijun Zhang,Juan Song,Chaofan Li 한국광학회 2020 Current Optics and Photonics Vol.4 No.5

Based on single-mode rate equations, we present an improved equivalent-circuit model for distributedfeedback (DFB) lasers that accounts for the effects of parasitic parameters and nonradiative recombination. This equivalent-circuit model is composed of a parasitic circuit, an electrical circuit, an optical circuit, and a phase circuit, modeling the circuit equations transformed from the rate equations. The validity of the proposed circuit model is verified by comparing simulation results to measured results in the literature. The results show that the slope efficiency and threshold current of the model are 0.22 W/A and 13 mA respectively. It is also shown that increasing bias current results in the increase of the relaxation-oscillation frequency. Moreover, we show that the larger the bias current, the lower the frequency chirp, increasing the possibility of extending the transmission distance of an optical-fiber communication system. The results indicate that the proposed circuit model can accurately predict a DFB laser’s static and dynamic characteristics.

Hydrogen sulfide alleviates hypothyroidism-induced myocardial fibrosis in rats through stimulating autophagy and inhibiting TGF-β1/Smad2 pathway

Xiong Song,Liangui Nie,Junrong Long,Junxiong Zhao,Xing Liu,Liuyang Wang,Da Liu,Sen Wang,Shengquan Liu,Jun Yang 대한약리학회 2023 The Korean Journal of Physiology & Pharmacology Vol.27 No.1

Hypothyroidism alone can lead to myocardial fibrosis and result in heart failure, but traditional hormone replacement therapy does not improve the fibrotic situation. Hydrogen sulfide (H2S), a new gas signaling molecule, possesses antiinflammatory, antioxidant, and anti-fibrotic capabilities. Whether H2S could improve hypothyroidism-induced myocardial fibrosis are not yet studied. In our study, H2S could decrease collagen deposition in the myocardial tissue of rats caused by hypothyroidism. Furthermore, in hypothyroidism-induced rats, we found that H2S could enhance cystathionine-gamma-lyase (CSE), not cystathionine β-synthase (CBS), protein expressions. Finally, we noticed that H2S could elevate autophagy levels and inhibit the transforming growth factor-β1 (TGF-β1) signal transduction pathway. In conclusion, our experiments not only suggest that H2S could alleviate hypothyroidism- induced myocardial fibrosis by activating autophagy and suppressing TGF-β1/ SMAD family member 2 (Smad 2) signal transduction pathway, but also show that it can be used as a complementary treatment to conventional hormone therapy.

Theoretical analysis of simply supported channel girder bridges

Hong-Song Hu,Jian-Guo Nie,Yu-Hang Wang 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.2

Channel girder bridges that consist of a deck slab and two side beams are good choices for railway bridges and urban rail transit bridges when the vertical clearance beneath the bridge is restricted. In this study, the behavior of simply supported channel girder bridges was theoretical studied based on the theory of elasticity. The accuracy of the theoretical solutions was verified by the finite element analysis. The global bending of the channel girder and the local bending of the deck slab are two contributors to the deformations and stresses of the channel girder. Because of the shear lag effect, the maximum deflection due to the global bending could be amplified by 1.0 to 1.2 times, and the effective width of the deck slab for determining the global bending stresses can be as small as 0.7 of the actual width depending on the width-tospan ratio of the channel girder. The maximum deflection and transversal stress due to the local bending are obtained at the girder ends. For the channel girders with open section side beams, the side beam twist has a negligible effect on the deflections and stresses of the channel girder. Simplified equations were also developed for calculating the maximum deformations and stresses.

Aeroelastic Simulation Using CFD/CSD Coupling Based on Precise Integration Method

Huang Chengde,Huang Jie,Song Xin,Zheng Guannan,Nie Xueyuan 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.3

Aeroelasticity studies the interaction between the aerodynamic loads and the flexible structures, and has gained much attention in the design of modern aircraft. Most of the existing computational fluid dynamics/computational structural dynamics (CFD/CSD) coupling approaches are based on Runge–Kutta method, central difference method, linear multi-step method and so on, which are conditionally stable and are unsuitable for the stiff problem that requires a very small time step to solve. In this paper, the precise integration method (PIM) formula is derived for the structural modal equations and then the PIM-based CFD/CSD coupling method is presented. The three-dimensional AGARD wing 445.6 and a sweptback wing are considered here for aeroelastic studies. The flutter results demonstrate that the presented method is comparable in accuracy to the traditional strong coupling method and has better numerical stability property than some exiting improved methods. For the static aeroelastic analyses, applying a large damping ratio to the structural equations helps to obtain the equilibrium quickly but may lead to the stiff problem, which was seldom discussed before. The results show that the presented PIM-based coupling method can overcome the stiff problem arising in static aeroelastic systems and is more efficient than the traditional coupling approach based on Runge–Kutta method, especially when a large damping ratio is applied.