Formation Mechanism Analysis and Detection of Charged Particles in an Aero-engine Gas Path

Wen, Zhenhua,Hou, Junxing,Jiang, ZhiQiang The Korean Society for Aeronautical and Space Scie 2015 International Journal of Aeronautical and Space Sc Vol.16 No.2

The components of an aero-engine gas path cannot be monitored in a timely way due to a lack of real-time monitoring technologies. As an attempt to address this problem, we have conducted research on a condition monitoring technology based on the charging characteristics of particles in an aero-engine gas path, and emphatically analyze the formation of particles in an aero-engine gas path, the charging mechanism of carbon particles and the factors that influence the charge quantity and polarity. The verification experiments are performed on the simulated experiment platform and a turbo-shaft engine test bench. The results show the carbon particles' carry charge, and an obvious change in the total electrostatic charge level in the aero-engine gas path due to the increased carbon particles produced by burning or abnormal metal particles; the charge number is related to the size of particles, and the bigger carbon particles carry a negative charge and metal particles carry a positive charge; the change in engine power can lead to an obvious change in the level of electrostatic charge in the gas path, and the change in electrostatic charge results from the extra carbon particles formed in the rich-oil burning process. The research provides a reference for establishing the baseline of electrostatic charge while the engine runs on different power. The study also demonstrates the validity of the electrostatic monitoring technology and establishes a base for developing the application of electrostatic monitoring technology in aero-engines.

Optimal SVM learning method based on adaptive sparse sampling and granularity shift factor

Hui Wen,Dongshun Jia,Zhiqiang Liu,Hang Xu,Guangtao Hao 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.4

To improve the training efficiency and generalization performance of a support vector machine (SVM) in a large-scale set, an optimal SVM learning method based on adaptive sparse sampling and the granularity shift factor is presented. The proposed method combines sampling optimization with learner optimization. First, an adaptive sparse sampling method based on the potential function density clustering is designed to adaptively obtain sparse sampling samples, which can achieve a reduction in the training sample set and effectively approximate the spatial structure distribution of the original sample set. A granularity shift factor method is then constructed to optimize the SVM decision hyperplane, which fully considers the neighborhood information of each granularity region in the sparse sampling set. Experiments on an artificial dataset and three benchmark datasets show that the proposed method can achieve a relatively higher training efficiency, as well as ensure a good generalization performance of the learner. Finally, the effectiveness of the proposed method is verified.

Formation Mechanism Analysis and Detection of Charged Particles in an Aero-engine Gas Path

Zhenhua Wen,Junxing Hou,ZhiQiang Jiang 한국항공우주학회 2015 International Journal of Aeronautical and Space Sc Vol.16 No.2

The components of an aero-engine gas path cannot be monitored in a timely way due to a lack of real-time monitoring technologies. As an attempt to address this problem, we have conducted research on a condition monitoring technology based on the charging characteristics of particles in an aero-engine gas path, and emphatically analyze the formation of particles in an aero-engine gas path, the charging mechanism of carbon particles and the factors that influence the charge quantity and polarity. The verification experiments are performed on the simulated experiment platform and a turbo-shaft engine test bench. The results show the carbon particles’ carry charge, and an obvious change in the total electrostatic charge level in the aero-engine gas path due to the increased carbon particles produced by burning or abnormal metal particles; the charge number is related to the size of particles, and the bigger carbon particles carry a negative charge and metal particles carry a positive charge; the change in engine power can lead to an obvious change in the level of electrostatic charge in the gas path, and the change in electrostatic charge results from the extra carbon particles formed in the rich-oil burning process. The research provides a reference for establishing the baseline of electrostatic charge while the engine runs on different power. The study also demonstrates the validity of the electrostatic monitoring technology and establishes a base for developing the application of electrostatic monitoring technology in aero-engines.

An Improved PSO Algorithm Based on Mutation Operator and Simulated Annealing

Xiaojun Deng,Zhiqiang Wen,Yu Wang,Pingan Xiang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.10

Particle swarm optimization (PSO) algorithm is simple stochastic global optimization technique, but it exists unbalanced global and local search ability, slow convergence speed and solving accuracy. An improved simulated annealing (ISAM) algorithm is introduced into the PSO algorithm with crossover and Gauss mutation to propose an improved PSO (ISAMPSO) algorithm based on the mutation operator and simulated annealing in this paper. In the ISAMPSO algorithm, the mutation operator of genetic algorithm is introduced into the SA algorithm as a generation mechanism of new solution in order to propose an improved simulated annealing algorithm with mutation (ISAM). Then the ISAM algorithm is introduced into the PSO algorithm to jump out the local optimum, effectively achieve the global optimum adjust and optimize the population, maintain the diversity of the population, improve the local search ability and convergence speed. Six classical functions are selected to test the performance of the proposed ISAMPSO algorithm. The simulation experiments results show that the proposed ISAMPSO algorithm can effectively overcomes the stagnation phenomenon and enhance the global search ability. The convergence speed and accuracy were better than the PSO algorithm.

Defect Detection of Oil and Gas Pipeline using Remote Field Eddy Current Technology

Mingjiang Shi,Lin Feng,Zhiqiang Huang,Mengfei Zhang,Hao Wen,Qing Liu 한국자기학회 2019 Journal of Magnetics Vol.24 No.3

To solve the problem of wall thickness reduction and defects of oil and gas pipeline caused by corrosion or erosion, a remote field eddy current (RFEC) testing method with coaxial double coil structure is proposed to detect corrosion residual wall thickness of oil and gas gathering pipelines. Based on electromagnetic field theories, RFEC technology is theoretically analyzed. The theoretical model of RFEC detection for coaxial double coil structure is established. The relationship between the voltage phase of detection signal and the wall thickness of pipeline is derived, and an evaluation method of the residual wall thickness of the pipeline based on the phase trough time of the RFEC detection signal is proposed. The parameters of RFEC probe are optimized by Finite Element Method, and the detection system is designed on the basis of it. The practicability and the correctness of the theoretical model of the detection system are verified by experiments. It can be used to detect the residual wall thickness of pipelines in real time under different media conditions.

Crop Production and Environment friendly-agriculture in China

Ming Zhao,Lifeng Fang,Zhiqiang Dong,Xianguo Zhu,Wen Jiang 한국작물학회 2005 한국작물학회 학술발표대회 논문집 Vol.2005 No.-

Uncovering Microstructure Evolution and Dynamic Softening Mechanism of Spray-Deposited AlZnMgCu Alloy Under Thermal Deformation

Guoai He,Cunxiao He,Yu Liu,Chao Liu,Zhiqiang Fu,Shuanghui Xu,Xiaofei Sheng,Zhu Xiao,Qinghong Wen 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9

Dynamic softening behavior has been of great concern in the aluminum alloys, which served a vital role in affecting themicrostructure, deformation resistance and the final mechanical properties. In this paper, spray deposition was applied tomanufacture AlZnMgCu alloy to refine the casting microstructure and reduce segregation. The microstructure responses andcorresponding mechanism during the thermal compression with various temperatures and various strain rates were multiscalecharacterized and uncovered using high-resolution EBSD. The results revealed that many broken and fine grains wereobserved in the uneven and jagged grain boundaries under the low temperatures and high strain rates, which indicated theoccurrence of partial discontinuous dynamic recrystallization (DDRX). In addition, high density dislocations were formedat original grain boundaries, where great amount of low angle grain boundaries (LAGBs) were appeared. With temperatureincreased and strains rate decreased, the LAGBs would evolve to the high angle grain boundaries (HAGBs) owing to theconsiderable dislocations migrated to the grain boundaries then accumulated, which triggered the occurrence of continuousdynamic recrystallization (CDRX). Two different dynamic recrystallization types were observed and factors that influenceddifferent dynamic recrystallization behaviors were clearly elaborated, and the corresponding mechanism was indicateddetailly.

Comparing Outcomes of Banana-Shaped and Straight Cages in Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Diseases: A Systematic Review and Meta-Analysis

Guang-Xun Lin,Li-Ru He,Jin-Niang Nan,Wen-Bin Xu,Keyi Xiao,Zhiqiang Que,Shang-Wun Jhang,Chien-Min Chen,Ming-Tao Zhu,Gang Rui 대한척추신경외과학회 2024 Neurospine Vol.21 No.1

Objective: This meta-analysis aims to refine the understanding of the optimal choice between different cage shapes in transforaminal lumbar interbody fusion (TLIF) by systematically comparing perioperative data, radiological outcomes, clinical results, and complications associated with banana-shaped and straight bullet cages. Methods: A meticulous literature search encompassing PubMed, Embase, Scopus, Web of Science, China Knowledge Network, and Wanfang Data was executed up to October 5, 2023. Inclusion criteria focused on studies comparing banana-shaped and straight bullet cages in TLIF. The quality of included studies was assessed using appropriate tools such as the Newcastle-Ottawa Scale (NOS) for nonrandomized studies. Rigorous evaluations were performed for radiographic outcomes, including disc height (DH), segmental lordosis (SL), lumbar lordosis (LL), subsidence, and fusion rates. Clinical outcomes were meticulously evaluated using visual analogue scale (VAS), Oswestry Disability Index (ODI), and complications. Results: The analysis incorporated 7 studies, involving 573 patients (297 with banana-shaped cages, 276 with straight cages), all with NOS ratings exceeding 5 stars. No statistically significant differences were observed in operative time, blood loss, or hospitalization between the 2 cage shapes. Banana-shaped cages exhibited greater changes in DH (p = 0.001), SL (p = 0.02), and LL (p = 0.01). Despite statistically higher changes in ODI for straight cages (26.33, p < 0.0001), the actual value remained similar to banana-shaped cages (26.15). Both cage types demonstrated similar efficacy in VAS, complication rates, subsidence, and fusion rates. Conclusion: Although banana-shaped cages can excel in restoring DH, SL, and LL, straight bullet cages can provide comparable functional improvements, pain relief, and complication rates.