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| 1 | Remaining useful life prediction based on the Wiener process for an aviation axial piston pump显示文摘An aviation hydraulic axial piston pump's degradation from comprehensive wear is a typical gradual failure model.Accurate wear prediction is difficult as random and uncertain characteristics must be factored into the estimation.The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump.The performance degradation model is described by the Wiener process to predict the remaining useful life(RUL) of the pump.Maximum likelihood estimation(MLE) is performed by utilizing the expectation maximization(EM) algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process.The RUL of the pump is then calculated according to the performance degradation model based on the Wiener process.Experimental results indicate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump,and thus the Wiener process-based method may effectively predicate the RUL of the pump. | WangXingjian LinSiru Wang Shaoping HeZhaomin ZhangChao | 2016 | Chinese Journal of Aeronautics2016，29，3： | 28 |
| 2 | Mechanical wear debris feature,detection,and diagnosis:A review显示文摘Mechanical debris is an important product of friction wear, which is also a crucial approach to know the running status of a machine. Many studies have been conducted on mechanical debris in related fields such as tribology, instrument, and diagnosis. This paper presents a comprehensive review of these studies, which summarizes wear mechanisms(e.g., abrasive wear, fatigue wear, and adhesive wear) and debris features(e.g., concentration(number), size, morphology, and composition), analyzes detection methods principles(e.g., offline: spectrograph and ferrograph, and online: optical method, inductive method, resistive-capacitive method, and acoustic method),reviews developments of online inductive methods, and investigates the progress of debris-based diagnosis. Finally, several notable problems are discussed for further studies. | Wei HONG Wenjian CAI Shaoping WANG Mileta M.TOMOVIC | 2018 | Chinese Journal of Aeronautics2018，31，5： | 19 |
| 3 | Flow field and pressure loss analysis of junction and its structure optimization of aircraft hydraulic pipe system显示文摘The flow field in junction is complicated due to the ripple property of oil flow velocity and different frequencies of two pumps in aircraft. In this study, the flow fields of T-junction and Y-junction were analyzed using shear stress transport (SST) model in ANSYS/CFX software. The simulation results identified the variation rule of velocity peak in T-junction with different frequencies and phase-differences, meanwhile, the eddy and velocity shock existed in the corner of the T-junction, and the limit working state was obtained. Although the eddy disappeared in Y-junction, the velocity shock and pressure loss were still too big. To address these faults, an arc-junction was designed. Based on the flow fields of arc-junction, the eddy in the junction corner disappeared and the maximum of velocity peak declined compared to T-and Y-junction. Additionally, 8 series of arc-junction with different radiuses were tested to get the variation rule of velocity peak. Through the computation of the pressure loss of three junctions, the arc-junction had a lowest loss value, and its pressure loss reached the minimum value when the curvature radius is 35.42 mm, meanwhile, the velocity shock has decreased in a low phase. | Li Xin Wang Shaoping | 2013 | Chinese Journal of Aeronautics2013，26，4： | 17 |
| 4 | Design and Simulation of Electro-hydrostatic Actuator with a Built-in Power Regulator显示文摘电动静液作动器(EHA)是一种功率电传(PBW)作动器,可将电能输入转换为局部液压能以实现飞行控制。通过取消中央液压源和液压管路,电动静液作动器的可靠性和效率获得提高,但是带宽和刚度受到限制。为解决上述问题,本文提出了一种基于能量调节的新型电动静液作动器。能量调节器由高压蓄能器和比例阀组成,可以根据不同的控制需求储存和管理液压能。提出了转移体积的概念用于评价调节器的工作能力。液压锁用于保持作动器的输出位置。仿真结果表明:经过优化的新结构有效扩展了系统频宽。 | Kang Rongjie Jiao Zongxia Wang Shaoping Chen Lisha | 2009 | Chinese Journal of Aeronautics2009，22，6： | 16 |
| 5 | Nonlinear dynamic modeling of a helicopter planetary gear train for carrier plate crack fault diagnosis显示文摘Planetary gear train plays a significant role in a helicopter operation and its health is of great importance for the flight safety of the helicopter.This paper investigates the effects of a planet carrier plate crack on the dynamic characteristics of a planetary gear train,and thus finds an effective method to diagnose crack fault.A dynamic model is developed to analyze the torsional vibration of a planetary gear train with a cracked planet carrier plate.The model takes into consideration nonlinear factors such as the time-varying meshing stiffness,gear backlash and viscous damping.Investigation of the deformation of the cracked carrier plate under static stress is performed in order to simulate the dynamic effects of the planet carrier crack on the angular displacement of carrier posts.Validation shows good accuracy of the developed dynamic model in predicting dynamic characteristics of a planetary gear train.Fault features extracted from predictions of the model reveal the correspondence between vibration characteristic and the conditions(length and position)of a planet carrier crack clearly. | Fan Lei Wang Shaoping Wang Xingjian Han Feng Lyu Huawei | 2016 | Chinese Journal of Aeronautics2016，29，3： | 16 |
| 6 | Fault diagnosis of an intelligent hydraulic pump based on a nonlinear unknown input observer显示文摘Hydraulic piston pumps are commonly used in aircraft. In order to improve the viability of aircraft and energy efficiency, intelligent variable pressure pump systems have been used in aircraft hydraulic systems more and more widely. Efficient fault diagnosis plays an important role in improving the reliability and performance of hydraulic systems. In this paper, a fault diagnosis method of an intelligent hydraulic pump system(IHPS) based on a nonlinear unknown input observer(NUIO) is proposed. Different from factors of a full-order Luenberger-type unknown input observer, nonlinear factors of the IHPS are considered in the NUIO. Firstly, a new type of intelligent pump is presented, the mathematical model of which is established to describe the IHPS. Taking into account the real-time requirements of the IHPS and the special structure of the pump, the mechanism of the intelligent pump and failure modes are analyzed and two typical failure modes are obtained. Furthermore, a NUIO of the IHPS is performed based on the output pressure and swashplate angle signals. With the residual error signals produced by the NUIO, online intelligent pump failure occurring in real-time can be detected. Lastly, through analysis and simulation, it is confirmed that this diagnostic method could accurately diagnose and isolate those typical failure modes of the nonlinear IHPS. The method proposed in this paper is of great significance in improving the reliability of the IHPS. | Zhonghai MA Shaoping WANG Jian SHI Tongyang LI Xingjian WANG | 2018 | Chinese Journal of Aeronautics2018，31，2： | 13 |
| 7 | Reliability and safety analysis of redundant vehicle management computer system显示文摘Redundant techniques are widely adopted in vehicle management computer(VMC) to ensure that VMC has high reliability and safety.At the same time,it makes VMC have special characteristics,e.g.,failure correlation,event simultaneity,and failure self-recovery.Accordingly,the reliability and safety analysis to redundant VMC system(RVMCS) becomes more diffcult.Aimed at the diffculties in RVMCS reliability modeling,this paper adopts generalized stochastic Petri nets to establish the reliability and safety models of RVMCS.Then this paper analyzes RVMCS operating states and potential threats to flight control system.It is verifed by simulation that the reliability of VMC is not the product of hardware reliability and software reliability,and the interactions between hardware and software faults can reduce the real reliability of VMC obviously.Furthermore,the failure undetected states and false alarming states inevitably exist in RVMCS due to the influences of limited fault monitoring coverage and false alarming probability of fault monitoring devices(FMD).RVMCS operating in some failure undetected states will produce fatal threats to the safety of flight control system.RVMCS operating in some false alarming states will reduce utility of RVMCS obviously.The results abstracted in this paper can guide reliable VMC and effcient FMD designs.The methods adopted in this paper can also be used to analyze other intelligent systems' reliability. | Shi Jian Meng Yixuan Wang Shaoping Bian Mengmeng Yan Dungong | 2013 | Chinese Journal of Aeronautics2013，26，5： | 11 |
| 8 | Hypoglycemic mechanism of polysaccharide from Cyclocarya paliurus leaves in type 2 diabetic rats by gut microbiota and host metabolism alteration显示文摘Diabetes mellitus is a serious threat to human health.Cyclocarya paliurus(Batal.)Iljinskaja(C.paliurus)is one of the traditional herbal medicine and food in China for treating type 2 diabetes,and the C.paliurus polysaccharides(CP)were found to be one of its major functional constituents.This research aimed at investigating the hypoglycemic mechanism for CP.It was found that CP markedly attenuated the symptoms of diabetes,and inhibited the protein expression of Bax,improved the expression of Bcl-2 in pancreas of diabetic rats,normalized hormones secretion and controlled the inflammation which contributed to the regeneration of pancreaticβ-cell and insulin resistance.CP treatment increased the beneficial bacteria genus Ruminococcaceae UCG-005 which was reported to be a key genus for protecting against diabetes,and the fecal short-chain fatty acids levels were elevated.Uric metabolites analysis showed that CP treatment helped to protect with the diabetes by seven significantly improved pathways closely with the nutrition metabolism(amino acids and purine)and energy metabolism(TCA cycle),which could help to build up the intestinal epithelial cell defense for the inflammation associated with the diabetes.Our study highlights the specific mechanism of prebiotics to attenuate diabetes through multi-path of gut microbiota and host metabolism. | Qiqiong Li Jielun Hu Qixing Nie Xiao Chang Qingying Fang Junhua Xie Haishan Li Shaoping Nie | 2021 | Science China(Life Sciences)2021，64，1： | 11 |
| 9 | Catalytic performance of Fe_3O_4-CoO/Al_2O_3 catalyst in ozonation of 2-(2,4-dichlorophenoxy) propionic acid,nitrobenzene and oxalic acid in water显示文摘Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe(NO3) 3·9H2O and Co(NO3) 2·6H2O as the precursors,and its catalytic performance was investigated in ozonation of 2-(2,4-dichlorophenoxy) propionic acid(2,4-DP) ,nitrobenzene and oxalic acid.The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation eciency during the degradation of each organic pollutant,and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism.The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance.In the catalytic ozonation of 2,4-DP,the apparent reaction rate constants(k) were determined to be 1.456×10-2 min-1 for ozonation alone and 4.740×10-2 min-1 for O3/Fe3O4-CoO/Al2O3.And O3/Fe3O4-CoO/Al2O3 had a larger Rct(6.614×10-9) calculated by the relative method than O3 did(1.800×10-9) ,showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical.Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid.The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree. | Shaoping Tong,Rui Shi,Hua Zhang,Chunan Ma College of Chemical Engineering and Materials Science,State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology,Zhejiang University of Technology,Hangzhou 310032,China | 2010 | Journal of Environmental Sciences2010，22，10： | 10 |
| 10 | Modeling of reliability and performance assessment of a dissimilar redundancy actuation system with failure monitoring显示文摘Actuation system is a vital system in an aircraft,providing the force necessary to move flight control surfaces.The system has a significant influence on the overall aircraft performance and its safety.In order to further increase already high reliability and safety,Airbus has implemented a dissimilar redundancy actuation system(DRAS) in its aircraft.The DRAS consists of a hydraulic actuation system(HAS) and an electro-hydrostatic actuation system(EHAS),in which the HAS utilizes a hydraulic source(HS) to move the control surface and the EHAS utilizes an electrical supply(ES) to provide the motion force.This paper focuses on the performance degradation processes and fault monitoring strategies of the DRAS,establishes its reliability model based on the generalized stochastic Petri nets(GSPN),and carries out a reliability assessment considering the fault monitoring coverage rate and the false alarm rate.The results indicate that the proposed reliability model of the DRAS,considering the fault monitoring,can express its fault logical relation and redundancy degradation process and identify potential safety hazards. | Wang Shaoping Cui Xiaoyu Shi Jian Mileta M.Tomovic Jiao Zongxia | 2016 | Chinese Journal of Aeronautics2016，29，3： | 10 |
| 11 | Adaptive Fuzzy Torque Control of Passive Torque Servo Systems Based on Small Gain Theorem and Input-to-state Stability显示文摘Passive torque servo system (PTSS) simulates aerodynamic load and exerts the load on actuation system, but PTSS endures position coupling disturbance from active motion of actuation system, and this inherent disturbance is called extra torque. The most important issue for PTSS controller design is how to eliminate the influence of extra torque. Using backstepping technique, adaptive fuzzy torque control (AFTC) algorithm is proposed for PTSS in this paper, which reflects the essential characteristics of PTSS and guarantees transient tracking performance as well as final tracking accuracy. Takagi-Sugeno (T-S) fuzzy logic system is utilized to compensate parametric uncertainties and unstructured uncertainties. The output velocity of actuator identified model is introduced into AFTC aiming to eliminate extra torque. The closed-loop stability is studied using small gain theorem and the control system is proved to be semiglobally uniformly ultimately bounded. The proposed AFTC algorithm is applied to an electric load simulator (ELS), and the comparative experimental results indicate that AFTC controller is effective for PTSS. | WANG Xingjian | 2012 | Chinese Journal of Aeronautics2012，25，6： | 10 |
| 12 | Cardiovascular dysfunction following spinal cord injury显示文摘Both sensorimotor and autonomic dysfunctions often occur after spinal cord injury(SCI). Particularly, a high thoracic or cervical SCI interrupts supraspinal vasomotor pathways and results in disordered hemodynamics due to deregulated sympathetic outflow. As a result of the reduced sympathetic activity, patients with SCI may experience hypotension, cardiac dysrhythmias, and hypothermia post-injury. In the chronic phase, changes within the CNS and blood vessels lead to orthostatic hypotension and life-threatening autonomic dysreflexia(AD). AD is characterized by an episodic, massive sympathetic discharge that causes severe hypertension associated with bradycardia. The syndrome is often triggered by unpleasant visceral or sensory stimuli below the injury level. Currently the only treatments are palliative – once a stimulus elicits AD, pharmacological vasodilators are administered to help reduce the spike in arterial blood pressure. However, a more effective means would be to mitigate AD development by attenuating contributing mechanisms, such as the reorganization of intraspinal circuits below the level of injury. A better understanding of the neuropathophysiology underlying cardiovascular dysfunction after SCI is essential to better develop novel therapeutic approaches to restore hemodynamic performance. | Elizabeth Partida Eugene Mironets Shaoping Hou Veronica J.Tom | 2016 | Neural Regeneration Research2016，11，2： | 10 |
| 13 | Variable load failure mechanism for high-speed load sensing electro-hydrostatic actuator pump of aircraft显示文摘This paper presents a novel transient lubrication model for the analysis of the variable load failure mechanism of high-speed pump used in Load Sensing Electro-Hydrostatic Actuator(LS-EHA). Focusing on the slipper/swashplate pair partial abrasion, which is considered as the dominant failure mode in the high-speed condition, slipper dynamic models are established. A forth sliding motion of the slipper on the swashplate surface is presented under the fact that the slipper center of mass will rotate around the center of piston ball when the swashplate angle is dynamically adjusted. Besides, extra inertial tilting moments will be produced for the slipper based on the theorem on translation of force, which will increase rapidly when LS-EHA pump operates under highspeed condition. Then, a dynamic lubricating model coupling with fluid film thickness field, temperature field and pressure field is proposed. The deformation effects caused by thermal deflection and hydrostatic pressure are considered. A numerical simulation model is established to validate the effectiveness and accuracy of the proposed model. Finally, based on the load spectrum of aircraft flight profile, the variable load conditions and the oil film characteristics are analyzed, and series of variable load rules of oil film thickness with variable speed/variable pressure/variable displacement are concluded. | Cun SHI Shaoping WANG Xingjian WANG Yixin ZHANG | 2018 | Chinese Journal of Aeronautics2018，31，5： | 8 |
| 14 | Heat Treatment Effect on Microstructure, Hardness and Wear Resistance of Cr26 White Cast Iron显示文摘High chromium cast iron(HCCI) is taken as material of coal water slurry pump impeller, but it is susceptible to produce serious abrasive wear and erosion wear because of souring of hard coal particles. The research on optimization of heat treatments to improve abrasive wear properties of HCCI is insufficient, so effect of heat treatments on the microstructure, hardness, toughness, and wear resistance of Cr26 HCCI is investigated to determine the optimal heat treatment process for HCCI. A series of heat treatments are employed. The microstructures of HCCI specimens are examined by using optical microscopy and scanning electron microscopy. The hardness and impact fracture toughness of as-cast and heat treated specimens are measured. The wear tests are assessed by a Type M200 ring-on block wear tester. The results show the following: With increase of the quenching temperature from 950 ℃ to 1050 ℃, the hardness of Cr26 HCCI increased to a certain value, kept for a time and then decreased. The optimal heat treatment process is 2 h quenching treatment at 1000 ℃, followed by a subsequent 2 h tempering at 400 ℃. The hardness of HCCI is related to the precipitation and redissolution of secondary carbides in the process of heat treatment. The subsequent tempering treatment would result in a slight decrease of hardness but increase of toughness. The wear resistance is much related to the 'supporting' effect of the matrix and the 'protective' effect of the hard carbide embedded in the matrix, and the wear resistance is further dependent on the hardness and the toughness of the matrix. This research can provide an important insight on developing an optimized heat treatment method to improve the wear resistance of HCCI. | ZHOU Shaoping SHEN Yehui ZHANG Hao CHEN Dequan | 2015 | Chinese Journal of Mechanical Engineering2015，28，1： | 7 |
| 15 | An adaptive-order particle filter for remaining useful life prediction of aviation piston pumps显示文摘An accurate estimation of the remaining useful life(RUL) not only contributes to an effective application of an aviation piston pump, but also meets the necessity of condition based maintenance(CBM). For the current RUL evaluation methods, a model-based method is inappropriate for the degradation process of an aviation piston pump due to difficulties of modeling, while a data-based method rarely presents high-accuracy prediction in a long period of time. In this work,an adaptive-order particle filter(AOPF) prognostic process is proposed aiming at improving long-term prediction accuracy of RUL by combining both kinds of methods. A dynamic model is initialized by a data-driven or empirical method. When a new observation comes, the prior state distribution is approximated by a current model. The order of the current model is updated adaptively by fusing the information of the observation. Monte Carlo simulation is employed for estimating the posterior probability density function of future states of the pump's degradation.With updating the order number adaptively, the method presents a higher precision in contrast with those of traditional methods. In a case study, the proposed AOPF method is adopted to forecast the degradation status of an aviation piston pump with experimental return oil flow data, and the analytical results show the effectiveness of the proposed AOPF method. | Tongyang LI Shaoping WANG Jian SHI Zhonghai MA | 2018 | Chinese Journal of Aeronautics2018，31，5： | 7 |
| 16 | Variations of precipitation characteristics during the period 1960–2014 in the Source Region of the Yellow River,China显示文摘Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a consequence of enhanced global hydrological cycle. The source region of the Yellow River(SRYR), locating within the Qinghai-Tibet Plateau, is sensitive to the global climate change due to its complex orography and fragile ecosystem. To understand the precipitation characteristics and its impacts on the environment in the region, we studied the characteristics of rainy days and precipitation amount of different precipitation classes, such as light(0–5 and 5–10 mm), moderate(10–15, 15–20 and 20–25 mm) and heavy(≥25 mm) rains by analyzing the precipitation data of typical meteorological stations in the SRYR during the period 1961–2014, as well as the trends of persistent rainfall events and drought events. Results showed that annual average precipitation in this area had a non-significant(P>0.05) increasing trend, and 82.5% of the precipitation occurred from May to September. Rainy days of the 0–5 mm precipitation class significantly decreased, whereas the rainy days of 5–10, 10–15, and 20–25 mm precipitation classes increased and that of ≥25 mm precipitation class decreased insignificantly. The persistent rainfall events of 1-or 2-day and more than 2-day showed an increasing trend, with the 1-or 2-day events being more frequent. Meanwhile, the number of short drought periods(≤10 days) increased while long drought periods(>10 days) decreased. Since the 0–5 mm precipitation class had a huge impact on the grasslands productivity; the 5–10, 10–15, and 20–25 mm precipitation classes had positive effects on vegetation which rely on the deep soil water through moving nutrients and water into the root zone of these vegetation or through the plant-microbe interactions; the ≥25 mm precipitation class contributed to the floods; and more persistent rainfall events and fewer long drought events inferred positive effects on agriculture. Thus, these results indicate grassland degradation, less risk of floods, and the upgrading impact of climate change on agriculture. This study may provide scientific knowledge for policymakers to sustain the eco-environmental resources in the SYSR. | Mudassar IQBAL WEN Jun WANG Shaoping TIAN Hui Muhammad ADNAN | 2018 | Journal of Arid Land2018，10，3： | 6 |
| 17 | Zr-MOFs loaded on polyurethane foam by polydopamine for enhanced dye adsorption显示文摘Zirconium-based metal-organic frameworks(Zr-MOFs)have attracted widespread attention due to their high specific surface area,high porosity,abundant metal active sites and excellent hydrothermal stability.However,Zr-MOFs materials are mostly powdery in nature and thus difficult to separate from aqueous media,which limits their application in wastewater treatment.In this study,PDA/Zr-MOFs/PU foam was constructed by growing Zr-MOFs nanoparticles on a dopamine-modified polyurethane foam substrate by in-situ hydrothermal synthesis as an adsorbent for removing dyes from wastewater.The results demonstrated that the polydopamine coating improves the dispersion of the Zr-MOFs nanoparticles on the substrate and enhances the interaction between the Zr-MOFs nanoparticles and the PU foam substrate.As a result,compared with Zr-MOFs/PU foam,the prepared PDA/ZrMOFs/PU foam exhibits higher adsorption capacity for crystal violet(CV)(63.38 mg/g)and rhodamine B(RB)(67.73 mg/g),with maximum adsorption efficiencies of CV and RB of 98.4%(pH=11)and 93.5%(pH=7),respectively,at a concentration of 10 mg/L.The PDA/Zr-MOFs/PU foam can simultaneously remove CV and RB from the mixed solution.Moreover,the PDA/ZrMOFs/PU foam still exhibits high stability and reusability after five cycles. | Jingjing Zhao Linqiong Xu Yaozhuo Su Hongwei Yu Hui Liu Shaoping Qian Wenge Zheng Yongqing Zhao | 2021 | Journal of Environmental Sciences2021，33，3： | 6 |
| 18 | Genome-and transcriptome-wide association studies provide insights into the genetic basis of natural variation of seed oil content in Brassica napus显示文摘Seed oil content(SOC)is a highly important and complex trait in oil crops.Here,we decipher the genetic basis of natural variation in SOC of Brassica napus by genome-and transcriptome-wide association studies using 505 inbred lines.We mapped reliable quantitative trait loci(QTLs)that control SOC in eight environments,evaluated the effect of each QTL on SOC,and analyzed selection in QTL regions during breeding.Six-hundred and ninety-two genes and four gene modules significantly associated with SOC were identified by analyzing population transcriptomes from seeds.A gene prioritization framework,POCKET(prioritizing the candidate genes by incorporating information on knowledge-based gene sets,effects of variants,genome-wide association studies,and transcriptome-wide association studies),was implemented to determine the causal genes in the QTL regions based on multi-omic datasets.A pair of homologous genes,BnPMT6s,in two QTLs were identified and experimentally demonstrated to negatively regulate SOC.This study provides rich genetic resources for improving SOC and valuable insights toward understanding the complex machinery that directs oil accumulation in the seeds of B.napus and other oil crops. | Shan Tang Hu Zhao Shaoping Lu Liangqian Yu Guofang Zhang Yuting Zhang Qing-Yong Yang Yongming Zhou Xuemin Wang Wei Ma Weibo Xie Liang Guo | 2021 | Molecular Plant2021，14，3： | 6 |
| 19 | Reliability estimation of mechanical seals based on bivariate dependence analysis and considering model uncertainty显示文摘The reliability estimation of mechanical seals is of crucial importance due to their wide applications in pumps in various mechanical systems.Failure of mechanical seals might cause leakage,and might lead to system failure and other relevant consequences.In this study,the reliability estimation for mechanical seals based on bivariate dependence analysis and considering model uncertainty is proposed.The friction torque and leakage rate are two degradation performance indicators of mechanical seals that can be described by the Wiener process,Gamma process,and inverse Gaussian process.The dependence between the two indicators can be described by different copula functions.Then the model uncertainty is considered in the reliability estimation using the Bayesian Model Average(BMA)method,while the unknown parameters in the model are estimated by Bayesian Markov Chain Monte Carlo(MCMC)method.A numerical simulation study and fatigue crack study are conducted to demonstrate the effectiveness of the BMA method to capture model uncertainty.A degradation test of mechanical seals is conducted to verify the proposed model.The optimal stochastic process models for two performance indicators and copula function are determined based on the degradation data.The results show the necessity of using the BMA method in degradation modeling. | Rentong CHEN Chao ZHANG Shaoping WANG Yujie QIAN | 2021 | Chinese Journal of Aeronautics2021，34，5： | 5 |
| 20 | Occurrence of human pathogenic bacteria carrying antibiotic resistance genes revealed by metagenomic approach: A case study from an aquatic environment显示文摘Antibiotic resistance genes(ARGs), human pathogenic bacteria(HPB), and HPB carrying ARGs are public issues that pose a high risk to aquatic environments and public health. Their diversity and abundance in water, intestine, and sediments of shrimp culture pond were investigated using metagenomic approach. A total of 19 classes of ARGs, 52 HPB species, and 7 species of HPB carrying ARGs were found. Additionally, 157, 104, and 86 subtypes of ARGs were detected in shrimp intestine, pond water, and sediment samples, respectively. In all the samples, multidrug resistance genes were the highest abundant class of ARGs. The dominant HPB was Enterococcus faecalis in shrimp intestine, Vibrio parahaemolyticus in sediments, and Mycobacterium yongonense in water, respectively. Moreover, E. faecalis(contig Intestine_364647)and Enterococcus faecium(contig Intestine_80272) carrying efr A, efr B and ANT(6)-Ia were found in shrimp intestine, Desulfosaricina cetonica(contig Sediment_825143) and Escherichia coli(contig Sediment_188430) carrying mex B and APH(3′)-IIa were found in sediments, and Laribacter hongkongensis(contig Water_478168 and Water_369477), Shigella sonnei(contig Water_880246),and Acinetobacter baumannii(contig Water_525520) carrying sul1, sul2, ere A, qac H, OXA-21, and mph D were found in pond water. Mobile genetic elements(MGEs) analysis indicated that horizontal gene transfer(HGT) of integrons, insertion sequences, and plasmids existed in shrimp intestine, sediment, and water samples, and the abundance of integrons was higher than that of other two MGEs. The results suggested that HPB carrying ARGs potentially existed in aquatic environments, and that these contributed to the environment and public health risk evaluation. | Renjun Zhou Shenzheng Zeng Dongwei Hou Jian Liu Shaoping Weng Jianguo He Zhijian Huang | 2019 | Journal of Environmental Sciences2019，31，6： | 5 |
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