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Zitong Zhou,Jinglong Chen,Yanyang Zi,Tong An 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
Fault identification for bearings of special electromechanical equipment is significant to avoid catastrophic accidents. However, spectral aliasing and nonstationarity resulted from variable speed condition make this task difficult. In this paper, a modified self-organizing maps (SOM) based on nonlinear neural weight updating way is proposed to solve the problem of bearing fault severity identification in variable speed condition. Firstly, a multi-domain features extraction method based on angular re-sampling technique is introduced. Then considering the nonlinear relationship between fault severity and fault features, the traditional Euclidian distance of SOM is substituted with the geodesic distance when update the neural weight and select the best-matching cell, which can improve the nonlinear identification ability of proposed method. Finally, two cases are performed and the results show that the method can identify bearing fault with different severities effectively and have practical significance when considering both accuracy and time cost compared with other methods.
Flow control of automobile with plasma vortex generator
Xingjun Hu,Jinglong Zhang,Zheng Hui,Yufei Luo,Peng Guo,Jingyu Wang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
In this study, a plasma actuator was used to examine the wake flow control of an automobile with the aid of wind tunnel test methods, such as surface pressure measurement and particle image velocimetry (PIV) measurement. The control mechanism and law of the plasma vortex generator in the wake field of an Ahmed model were described. The effects of certain factors were analyzed. Results showed that the streamwise vortex induced by a dielectric-barrier-discharge vortex generator (DBD-VG) could promote the mixing of high-speed airflow above the slanted surface at the end of the model and low-speed airflow near the wall by increasing airflow turbulence, thereby inhibiting the generation of separation bubbles and reducing drag. Drag reduction decreased as the total discharge length of the DBD-VG decreased, but its backward distance had the largest effect on the drag reduction rate, followed by its counter distance. Meanwhile, the shortening of the streamwise length had the least effect on the drag reduction rate. When installing the DBG-VG, the end of the actuator should be arranged near the separation line to enable the generation and development of the streamwise vortex before the separation line to achieve the strongest flow control effect. The DBD-VG need not be arranged precisely at the airflow separation point, which demonstrates its favorable versatility. At low speeds, a maximum drag reduction rate of -8.51 % was obtained at an excitation voltage of 13 kV under the control of the DBD-VG, which demonstrated its strong flow control capability.
Muhammad Samiuddin,Jinglong Li,Muhammad Muzamil,Sumair Uddin,Jiangtao Xiong 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.5
CoCrNi medium entropy alloy (MEA) recently gained a lot of attention from the scientific community due to its excellentmechanical properties at cryogenic temperatures. AISI 304 stainless steel is also a commonly used material in cryogenicenvironments. Therefore, the main objective of this research was to join CoCrNi MEA with AISI 304 stainless steel to obtaincombinatorial properties for cryogenic applications. Vacuum diffusion welding process was utilized under different processingparameters. Three levels of welding temperatures and bonding time were selected and the influence of these parameterswere investigated using microstructural characterization. Electron microprobe analysis, electron backscattered diffraction,and SEM with EDX analysis were used in the analysis of bond interface regions. At low welding temperature and time, welddiscontinuities were formed which were drastically suppressed when both the parameters increased. Formation of IMCs wasalso found along with the bond interface and was significantly reduced upon increasing welding temperature and bondingtime. Moreover, at higher parametric values thick bond interface was formed and it was concluded that its developmentwas mainly due to the diffusion of Fe atoms. The quality of the bond interface was determined through shear testing andits fractography was also executed to correlate the processing parameters with the joint’s shear strength. Diffusivities andactivation energies of the constituent elements were also calculated.
Dimensionless study on dynamics of pressure controlled mechanical ventilation system
Yan Shi,Jinglong Niu,Maolin Cai,Weiqing Xu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2
Dynamics of mechanical ventilation system can be referred in pulmonary diagnostics and treatments. In this paper, to convenientlygrasp the essential characteristics of mechanical ventilation system, a dimensionless model of mechanical ventilation system is presented. For the validation of the mathematical model, a prototype mechanical ventilation system of a lung simulator is proposed. Through thesimulation and experimental studies on the dimensionless dynamics of the mechanical ventilation system, firstly, the mathematical modelis proved to be authentic and reliable. Secondly, the dimensionless dynamics of the mechanical ventilation system are obtained. Last, theinfluences of key parameters on the dimensionless dynamics of the mechanical ventilation system are illustrated. The study provides anovel method to study the dynamic of mechanical ventilation system, which can be referred in the respiratory diagnostics and treatment.
Product Safety Risk Assessment Approach to Sustainable Design
Bin He,Jiachi Wu,Jinglong Xiao 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.3
As a renewable and clean energy source, marine wind power has become an important direction. However, there are few studies on the safety risk assessment of offshore platforms from the design stage. Therefore, based on the project of the 2000-ton offshore wind power installation platform, the risk characteristics of the offshore platform during the design stage have been systematically studied. This paper is to take the safety assessment process of the offshore wind power installation platform design stage as an example, to devote to the general method of exploring the safety assessment of the offshore platform, quantify the load on the offshore platform under various working conditions, and calculate the strength. The impact of the safety assessment has a good guiding significance in solving how the ocean platform can achieve sustainable development from the design stage. The results validate the effectiveness of the proposed method.
Ziqiang, Zhou,Feng, Feng,Jinglong, Zhang,Yihui, Xiong,Xinyi, Ping,Qun, Huang 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.1 No.1
The pressure-composition-temperature(PCT) curves of $Mm_{0.6}Ml_{0.4}Ni_{5_x}Co_{x}(x{\leqslant}2.5)$hydrogne stroage alloys(HSA) are determined and the mathermatical model of PCT curve the author proposed is applied to analyse the data of PCT curve of the alloy system. It been shown from the results that the PCT curve of $Mm_{0.6}Ml_{0.4}Ni_{5-x}Co_{x}$can also be modeled by the mathematical model and the calculated PCT curves are in good agreement with the experimental curves. A lot of physical parameters of these alloys which are very useful are estimated from the modeling.
DRAG REDUCTION PREDICTION OF AHMED MODEL WITH TRAVELING WAVE BASED ON BP NEURAL NETWORK
Hu Xingjun Hu,Jinglong Zhang,Yufei Luo,Jingyu Wang,Pengzhan Ma,Wei Lan,Chunbo Dong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5
In this paper, a traveling wave model is proposed to explore its influence on the aerodynamic drag of a Ahmed model, the experimental and numerical results of aerodynamic drag coefficient CD for the Ahmed model are in good agreement. Then by defining the aerodynamic benefit coefficient ΔCD as the evaluation index for the orthogonal experiment, range analysis is conducted to determine the influences of the amplitude A, wavelength λ and frequency ω of the wave and the vehicle speed u on ΔCD. After the analysis it can been found that λ has the least importance among these parameters, hence A, ω and u are used to construct the 105 samples for training the BP neural network to predict ΔCD, results show that ΔCD obtained from the neural network is significantly affected by the parameters of traveling wave. The prediction accuracy of the network is furtherly verified by another 15 samples which are also built on A, ω and u, and the corresponding data overlap rate of ΔCD is 96 %, so it can be concluded that the BP neural network constructed in this paper is accurate enough to predict ΔCD.
Lingli Ni,Pengyin Zhang,Jing Chen,Jinglong Jiang,Shijie Ding 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.6
Palygorskite (PAL) as a natural one-dimensional nanomaterial has attracted tremendous attention as reinforcement agent in polymer nanocomposites. But its intrinsic existing form of aggregates or bundles and hydrophilic properties, highly requires an eco-efficient and environmentally benign approach for both of the disaggregation and organo-modification of PAL. We report a facile and effective process to achieve individualized organo-modified PAL fibers. It was carried out through surface modification reactions in the form of PAL iso-propanol gels with various alkyl and functional silanes. In contrast to the modifications in highly toxic solvent of toluene, reactions in iso-propanol make it possible to modify the surface of individual PAL fibers to obtain isolated organo-modified PAL fibers. With such a relatively green procedure, even higher amount of organic substituent has been grafted on to the surface of PAL fibers. Consequently, excellent dispersion of modified PAL nanofibers in acrylate polymer coatings was achieved, which exhibits outstanding corrosion protection properties.