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基于LMD与AO-PNN的中介轴承故障诊断方法

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航空发动机 2024年第2期50卷 114-120页

作者：徐石栾孝驰李彦徵沙云东郭小鹏沈阳航空航天大学航空发动机学院沈阳110136 中国航发沈阳发动机研究所沈阳110015

针对航空发动机中介轴承受噪声干扰大、传递路径复杂导致采用传统方法难以进行故障诊断的问题,提出了一种基于局部均值分解(LMD)与相关系数-能量比-峭度准则、结合天鹰座优化算法(AO)优化概率神经网络(PNN)的中介轴承故障诊断方法。使用... 详细信息

针对航空发动机中介轴承受噪声干扰大、传递路径复杂导致采用传统方法难以进行故障诊断的问题,提出了一种基于局部均值分解(LMD)与相关系数-能量比-峭度准则、结合天鹰座优化算法(AO)优化概率神经网络(PNN)的中介轴承故障诊断方法。使用LMD对传感器采集的振动信号进行分解;利用相关系数-能量比-峭度准则判决筛选分解得到的PF分量,重构筛选后的信号;计算重构信号的多尺度排列熵(MPE),以构建特征向量;通过AO优化的PNN的平滑因子,将优化后的神经网络用于中介轴承的故障诊断。基于中介轴承故障试验数据对诊断结果进行了分析,结果表明:提出的方法可以有效诊断高背景噪声、复杂路径干扰下的航空发动机中介轴承的典型故障,与粒子群优化的概率神经网络方法(PSO-PNN)和传统的PNN方法相比,其诊断准确率分别提高了3.875%和8.125%,具有较好的全局收敛性和计算鲁棒性。

关键词：局部均值分解故障诊断相关系数-能量比-峭度准则多尺度排列熵天鹰座优化算法中介轴承航空发动机

Estimation method for random sonic fatigue life of thin-walled structure of a combustor liner based on stress probability distribution

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航空动力学报 2011年第4期26卷 727-734页

作者： sha yun-dong GUO Xiao-peng LIAO Lian-fang XIE Li-juan Liaoning Key Laboratory of Digital Technology Simulation and Test Technique College of Power and Energy Engineering Shenyang Aerospace University Shenyang 110136 China Shenyang Aeroengine Research Institute Aviation Industry Corporation of China Shenyang 110015 China

As to the sonic fatigue problem of an aero-engine combustor liner structure under the random acoustic loadings,an effective method for predicting the fatigue life of a structure under random loadings was ***,the probability distribution of Von Mises stress of thin-walled structure under random loadings was studied,analysis suggested that probability density function of Von Mises stress process accord approximately with two-parameter Weibull *** formula for calculating Weibull parameters were *** on the Miner linear theory,the method for predicting the random sonic fatigue life based on the stress probability density was developed,and the model for fatigue life prediction was *** an example,an aero-engine combustor liner structure was *** power spectrum density(PSD) of the vibrational stress response was calculated by using the coupled FEM/BEM(finite element method/boundary element method) model,the fatigue life was estimated by using the constructed *** considering the influence of the wide frequency band,the calculated results were *** analysis shows that the estimated results of sonic fatigue of the combustor liner structure by using Weibull distribution of Von Mises stress are more conservative than using Dirlik distribution to some *** results show that the methods presented in this paper are practical for the random fatigue life analysis of the aeronautical thin-walled structures.

关键词： thin-walled structure sonic fatigue life estimation probability density function(PDF) power spectrum density(PSD)

基于应力概率密度和功率谱密度法的随机声疲劳寿命预估方法研究

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振动与冲击 2010年第1期29卷 162-165页

作者：沙云东郭小鹏张军沈阳航空工业学院辽宁省数字化工艺仿真与试验技术重点实验室沈阳110136

针对航空发动机燃烧室火焰筒结构的声疲劳问题,研究了一种用于随机载荷下结构疲劳寿命预估的有效方法。首先,对薄壁结构在随机载荷作用下的Von Mises应力过程的概率分布作了研究,给出了应力峰值概率密度函数的表达式。基于Miner线性理论... 详细信息

针对航空发动机燃烧室火焰筒结构的声疲劳问题,研究了一种用于随机载荷下结构疲劳寿命预估的有效方法。首先,对薄壁结构在随机载荷作用下的Von Mises应力过程的概率分布作了研究,给出了应力峰值概率密度函数的表达式。基于Miner线性理论,提出了基于应力概率密度和功率谱密度法的随机声疲劳寿命预估方法,并建立了疲劳寿命预估模型。以某型航空发动机燃烧室火焰筒结构为例,在采用耦合的有限元和边界元方法计算出随机声疲劳应力基础上,应用所建立的模型进行了疲劳寿命估算,并对计算结果进行了宽带修正。结果表明,该方法对航空薄壁结构随机疲劳寿命分析具有实用性。

关键词：声疲劳疲劳寿命 Von Mises应力概率密度功率谱密度

Quantifying peripapillary vessel density and retinal nerve fibre layer in type 1 diabetic children without clinically detectable retinopathy using OCTA

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International Journal of Ophthalmology(English edition) 2024年第2期17卷 278-281页

作者： Ling Chen yun Feng sha-sha Zhang Yan-Fang Liu Ping Lin Xi’an Children’s Hospital Affiliated to Xi’an Jiaotong University Xi’an 710002Shaanxi ProvinceChina

AIM:To quantify changes in radial peripapillary capillary vessel density(ppVD)and the peripapillary retinal nerve fiber layer(pRNFL)in children with type 1 diabetes without clinical diabetic retinopathy by optical coherence tomography angiography(OCTA),providing a basis for early retinopathy in children with type 1 ***:This was a retrospective study.A total of 30 patients(3–14y)with type 1 diabetes without clinical diabetic retinopathy(NDR group)were included.A total of 30 age-matched healthy subjects were included as the normal control group(CON group).The HbA1c level in the last 3mo was measured once in the NDR *** pRNFL thickness and ppVD were automatically measured,and the mean pRNFL and ppVD were calculated in the nasal,inferior,temporal,and superior *** changes in ppVD and pRNFL in the two groups were ***:Compared with CON group,the nasal and superior ppVDs decreased in the NDR group(all P0.05).Person and Spearman correlation analysis of ppVD and pRNFL thickness in each quadrant of the NDR group showed a positive correlation between nasal and superior(all P0.05).There was no significant correlation between the HbA1c level and ppVD and pRNFL in any quadrant(all P>0.05).There was no significant correlation between the course of diabetes mellitus and ppVD and pRNFL in any quadrant(all P>0.05).CONCLUSION:ppVD and pRNFL decrease in eyes of children with type 1 diabetes before clinically detectable retinopathy and OCTA is helpful for early monitoring.

关键词： diabetic retinopathy children peripapillary vessel density peripapillary retinal nerve fiber layer optical coherence tomography angiography

Overstory functional groups indicate the legacy of land use in a secondary tropical forest in southwestern China

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Journal of Forestry Research 2024年第5期35卷 91-105页

作者： yun Deng Wenfu Zhang Min Cao Jinlong dong Hui Chen Xiaobao Deng Jiajia Liu Xiaoyang Song shangwen Xia Liqing sha Shengdong Yuan Luxiang Lin CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303People’s Republic of China Center for Plant Ecology Core Botanical GardensChinese Academy of SciencesMengla 666303People’s Republic of China National Forest Ecosystem Research Station at Xishuangbanna Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303People’s Republic of China Department of Life Sciences Fudan UniversityShanghai 570228People’s Republic of China Department of Life Sciences University of Chinese Academy of SciencesBeijing 100049People’s Republic of China

Anthropogenic disturbances are widespread in tropical forests and influence the species composition in the ***,the impacts of historical disturbance on tropical forest overstory recovery are unclear due to a lack of disturbance data,and previous studies have focused on understory *** this study,the purpose was to deter-mine the influence of historical disturbance on the diver-sity,composition and regeneration of overstory species in present *** the 20-ha Xishuangbanna tropical sea-sonal rainforest dynamics plot in southwestern China,the historical disturbance boundaries were delineated based on panchromatic photographs from *** that drove species clustering in the overstory layer(DBH≥40 cm)were analyzed and the abundance,richness and composition of these species were compared among different tree groups based on multiple regression tree *** coefficient of variation of the brightness value in historical panchro-matic photographs from 1965 was the primary driver of spe-cies clustering in the overstory *** abundance and richness of overstory species throughout the regeneration process were similar,but species composition was always *** the proportion of large-seeded and vigorous-sprouting species showed no significant differ-ence between disturbed and undisturbed forests in the tree-let layer(DBH<20 cm),the difference became significant when DBH *** findings highlight that historical disturbances have strong legacy effects on functional group composition in the overstory and the recovery of overstory species was *** group composi-tion can better indicate the dynamics of overstory species replacement during secondary succession.

关键词： Historical disturbance Legacy effects Secondary forests Overstory species Functional groups

Theoretical study on the effect of H_(2)O on the formation mechanism of NO_(x) precursors during indole pyrolysis

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Frontiers of Chemical Science and Engineering 2024年第6期18卷 99-112页

作者： Ziqi Wang Jun Shen Xuesong Liu sha Wang Shengxiang Deng Hai Zhang yun Guo School of Mechanical and Automotive Engineering Shanghai University of Engineering ScienceShanghai 201620China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The incineration technology of kitchen waste is one of the effective technologies to achieve the resource utilization of municipal solid *** is an important stage of *** is a rich initial product in the pyrolysis process of kitchen waste,and the presence of H_(2)O has a significant impact on the decomposition of indole to form NO_(x) ***,this study uses density functional theory method to study the effect of H_(2)O on the thermal decomposition of indole to produce NH_(3),HNCO,and *** H_(2)O participates in the reaction,it can provide oxidative groups to generate a new product HNCO,which is different from the previous findings by indole pyrolysis without the presence of H_(2)***,this study theoretically proves that NH_(3) is easier to form than *** is consistent with the phenomenon that NH_(3) release is higher than HCN release in pyrolysis *** addition,compared with the individual pyrolysis of indole,the participation of H_(2)O reduces the energy barriers for the formation of NH_(3) and HCN during indole pyrolysis,thereby promoting the formation of NH_(3) and HCN.

关键词： indole pyrolysis H_(2)O NO_(x)precursors DFT

Lenvatinib combined with sintilimab plus transarterial chemoembolization as first-line treatment for advanced hepatocellular carcinoma

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World Journal of Clinical Cases 2024年第2期12卷 285-292页

作者： sha-sha Sun Xiao-Di Guo Wen-dong Li Jing-Long Chen Department of Oncology Capital Medical University Affiliated Beijing Ditan HospitalBeijing 100015China

BACKGROUND Recently,combination therapy has shown a better trend towards improved tumour response and survival outcomes than monotherapy in patients with hepatocellular carcinoma(HCC).However,research on triple therapy[lenvatinib+sintilimab+transarterial chemoembolization(TACE)]as a first-line treatment for advanced HCC is *** To evaluate the safety and efficacy of triple therapy as a first-line treatment for advanced *** HCC patients with Barcelona Clinic Liver Cancer stage C treated with triple therapy were *** patients were treated with lenvatinib every day and sintilimab once every 3 ***,TACE was performed every 4-6 wk if *** primary outcome of the study was overall survival(OS).The secondary outcomes were the objective response rate(ORR),disease control rate(DCR),and incidence of adverse *** Forty HCC patients who underwent triple therapy were retrospectively analysed from January 2019 to January *** a median follow-up of 8.5 months,the 3-,6-,and 12-mo OS rates were 100%,88.5%,and 22.5%,*** ORR and DCR were 45%and 90%,*** median progressive free survival and median OS were not *** complications were observed in 76%of the patients(grade 3,15%;grade 4,2.5%).CONCLUSION Combination therapy comprising lenvatinib,sintilimab and TACE achieved promising outcomes in advanced HCC patients and had manageable effects.

关键词： Lenvatinib Sintilimab Advanced hepatocellular carcinoma Combination therapy Tumor response

燃烧条件下火焰筒温度及噪声载荷特性实验研究

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推进技术 2023年第11期44卷 187-197页

作者：邹学锋燕群郭定文沙云东中国飞机强度研究所强度与结构完整性全国重点实验室陕西西安710065 北京航空航天大学沈元学院北京100191 沈阳航空航天大学航空航天工程学部辽宁沈阳110136

航空发动机燃烧室内部高温、气动及噪声等复杂载荷环境是导致火焰筒结构产生裂纹的主要因素之一,掌握火焰筒结构表面载荷特性及其与燃烧参数之间的关系,对于其强度评估非常重要。本文依据某型发动机真实构型设计了典型火焰筒试验件,搭... 详细信息

航空发动机燃烧室内部高温、气动及噪声等复杂载荷环境是导致火焰筒结构产生裂纹的主要因素之一,掌握火焰筒结构表面载荷特性及其与燃烧参数之间的关系,对于其强度评估非常重要。本文依据某型发动机真实构型设计了典型火焰筒试验件,搭建了模拟燃烧试验平台,发展了热电偶/示温漆组合测温和基于波导管的噪声测试方法,获得了不同燃烧状态下火焰筒表面的温度与噪声载荷分布特征,通过对比试验给出了进口温度、流量、供油量等参数对结构载荷的影响规律。结果表明,火焰筒表面噪声总声压级峰值超过150d B,总声压级、频率特性及分布特征与燃烧状态和结构振动特性等因素相关。

关键词：航空发动机火焰筒结构强度声载荷温度场

Synergistic Brønsted Base/Photoredox-Catalyzed Three-Component Coupling with Malonates to Synthesize δ-Hydroxy Esters and δ-Keto Esters

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Chinese Journal of Chemistry 2024年第9期42卷 957-962页

作者： Ting Li Wei Wang Ming dong Zhije Zhang sha Yu Zhengchu Chen Siping Wei dong Yi Green Pharmaceutical Technology Key Laboratory of Luzhou City Central Nervous System Drug Key Laboratory of Sichuan ProvinceSchoolof PharmacySouthwestMedicalUniversityLuzhouSichuan 646000China Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province LuzhouSichuan 646000China

Multicomponent alkene 1,2-dicarbofunctionalizations(DCFs)have emerged as a powerful strategy to rapidly incorporate both two carbon subunits across one C-C double bond in one step for enhancing molecular complexity and *** the best of our knowledge,there is only one report on photoredox-catalyzed three-component DCFs with malonates through the radical−radical cross-coupling,while photoredox-catalyzed radical-polar crossover(RPC)-type DCFs with malonates were still ***,we describe a redox-neutral RPC-type 1,2-dialkylation of styrenes with malonates and aldehydes through the synergistic Brønsted base/photoredox catalysis *** transition-metal-free strategy provides an efficient and clean approach to a broad variety ofδ-hydroxy esters and also features exceptionally mild conditions,wide compatibility of substrate scope and functional groups,and high atomic ***,three-component 1,2-alkylacylation from the same starting materials was achieved in one-pot manner through such RPC-type coupling and subsequent two-electron oxidation process,providing a set ofδ-keto esters of interest in pharmaceutical research.

关键词： Alkene difunctionalization Photoredox catalysis Malonates Radical reactions C-C coupling Synthetic methods Aldehydes Alkylation Multicomponentreactions