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Multi-blade rubbing characteristics of the shaft-disk-blade-casing system with large rotation

Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 111-136页

作者： Zhiyuan WU Linchuan ZHAO Han yan ge yan Ao CHEN Wenming ZHANG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Institute of Aerospace Systems Engineering Shanghai 201108China

Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.

关键词： shaft-disk-blade-casing(SDBC) large rotation spin and whirl multi-blade rubbing rotational effect

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Molecular packing tuning via chlorinated end group enables efficient binary organic solar cells over 18.5%

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Carbon Energy 2024年第3期6卷 196-203页

作者： Yafeng Li Zhenyu Chen Xingzheng yan Ziyi ge Zhejiang Business Technology Institute NingboZhejiangChina Zhejiang Engineering Research Center for Energy Optoelectronic Materials and Devices Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingboZhejiangChina Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijingChina

Designing novel nonfullerene acceptors(NFAs)is of vital importance for the development of organic solar cells(OSC).Modification on the side chain and end group are two powerful tools to construct efficient NFAs.Here,based on the high-performance L8BO,we selected 3-ethylheptyl to substitute the inner chain of 2-ethylhexyl,obtaining the backbone of BON3.Then we introduced different halogen atoms of fluorine and chlorine on 2-(3-oxo-2,3-dihydro-1Hinden-1-ylidene)malononitrile end group(EG)to construct efficient NFAs named BON3-F and BON3-Cl,respectively.Polymer donor D18 was chosen to combine with two novel NFAs to construct OSC devices.Impressively,D18:BON3-Cl-based device shows a remarkable power conversion efficiency(PCE)of 18.57%,with a high open-circuit voltage(V_(OC))of 0.907 V and an excellent fill factor(FF)of 80.44%,which is one of the highest binary PCE of devices based on D18 as the donor.However,BON3-F-based device shows a relatively lower PCE of 17.79%with a decreased FF of 79.05%.The better photovoltaic performance is mainly attributed to the red-shifted absorption,higher electron and hole mobilities,reduced charge recombination,and enhanced molecular packing in the D18:BON3-Cl films.Also,we performed stability tests on two binary systems;the D18:BON3-Cl and D18:BON3-F devices maintain 88.1%and 85.5%of their initial efficiencies after 169 h of storage at 85°C in an N2-filled glove box,respectively.Our work demonstrates the importance of selecting halogen atoms on EG and provides an efficient binary system of D18:BON3-Cl for further improvement of PCE.

关键词： binary organic solar cell chlorinated end group molecular packing

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Preparation and performance of novel magnetic phase-change-microcapsule-supported Bi_(2)WO_(6)catalyst

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Chinese Chemical Letters 2024年第3期35卷 158-161页

作者： Zhuoni Jiang Zhiqing ge Shuo yan Jingjing Shu Mozhen Wang Xuewu ge Key Laboratory of Precision and Intelligent Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China School of Materials Science and Engineering Southwest University of Science and TechnologyMianyang 621010China

The design and synthesis of novel photocatalyst with self-temperature control function is an important topic in the field of advanced environmental functional materials.In this work,submicron-sized magnetic phase change microcapsules composed of paraffin core and Fe_(3)O_(4)-loaded silica shell are prepared,on which the Bi_(2)WO_(6)crystals is grown in situ through hydrothermal reaction to obtain novel magnetic phase-change-microcapsule-supported Bi_(2)WO_(6)catalyst(MP@FS/BWO).The MP@FS/BWO has a paraffin encapsulation ratio of 57.1%,and the phase change enthalpy of 105.1 J/g in a temperature range of 50–60℃,which endows the MP@FS/BWO with a certain self-temperature regulation ability.MP@FS/BWO shows excellent catalytic performance in the decomposition of rhodamine B under the simulated sunlight irradiation.After the light source is turned off,it still has good catalytic ability by maintaining high temperature due to its temperature control function based on the phase transition process.The MP@FS/BWO can be easily recycled by magnetic separation and shows good structural stability and reusability.This work provides a new idea for the development of long-effect and energy-saving outdoor photocatalysts.

关键词： Photocatalyst Phase change microcapsules Self-temperature regulation Bismuth tungstate Magnetic separation

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Carbon efficiency modeling and optimization of solar-powered cellular networks

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Science China(Information Sciences) 2024年第5期67卷 228-243页

作者： Yuxi ZHAO Xiaohu ge Wen yan Tao HAN Yi ZHONG School of Electronic Information and Communications Huazhong University of Science and Technology Huawei Technology Co. Ltd.

As wireless communication traffic experiences rapid growth, the carbon emissions caused by the communication industry are also on the rise. To achieve “carbon neutrality”, researchers are considering the use of renewable energy sources to power cellular networks, thereby reducing carbon emissions. However, a challenge arises when using renewable energy, specifically owing to the unpredictable nature of both the energy consumption of the cellular network and the power generation from renewable sources. This inconsistency results in low renewable energy utilization and reduced carbon efficiency. Herein, we construct a carbon efficiency model of solar-powered cellular networks using practical data from solar radiation. We propose a mechanism that alternately optimizes the performance of the renewable energy network and the cellular network. This approach is based on convex optimization theory and the Dinkelback algorithm, and it leads to the design of a carbon efficiency optimization algorithm. This algorithm aims to improve the carbon efficiency of cellular networks and reduce their carbon emissions. Simulation results demonstrate that our optimization scheme yields a maximum improvement of 2.56 × 108bps/g in the carbon efficiency of the cellular network as compared to conventional power allocation schemes such as the traditional water filling method and heuristic energy sharing and charge/discharge algorithms.

关键词： cellular networks renewable energy carbon efficiency convex optimization theory dinkelbach

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Facile access to C-N bonds via unexpected side reactions of Knoevenagel condensation and their application in high-efficiency organic solar cells

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Science China Chemistry 2024年第1期67卷 323-329页

作者： Daobin yang Shuncheng yang Hongqian Wang Lin Xie Pengyu yan Ziyi ge Zhejiang Engineering Research Center for Energy Optoelectronic Materials and Devices Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China School of Materials Science and Chemical Engineering Ningbo UniversityNingbo 315211China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

The construction of C-N bonds is of great importance in the fields of biology,medicine,chemistry and materials science.Here,the replacement of organic base from pyridine to piperidine in the Knoevenagel condensation process unexpectedly yields a series of novel organic molecules containing C-N bonds.Interestingly,the synthesis method does not require any external transition-metals catalysis,and photo-/electro-catalysis.Additionally,when the new compound 1b is added as a third component to a well-known binary system of PM6:Y6,the efficiency of the organic solar cell is significantly improved,resulting in an outstanding efficiency of 18.0%,which is one of the highest values reported to date for PM6:Y6-based ternary organic solar cells.

关键词： C-N bonds Knoevenagel condensation cross-coupling reaction third component organic solar cells

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Exploring the correlation between temperature and crime:A case-crossover study of eight cities in America

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Journal of Safety Science and Resilience 2024年第1期5卷 13-36页

作者： Jinming Hu Xiaofeng Hu Xin’ge Han yan Lin Huanggang Wu Bing Shen School of Information Technology and Cyber Security People’s Public Security University of ChinaBeijing 100038China Center for Capital Social Safety People’s Public Security University of ChinaBeijing 100038China China Association for Public Safety Beijing 100084China School of Emergency Management and Safety Engineering China University of Mining and TechnologyBeijing 100083China School of International Police Studies People’s Public Security University of ChinaBeijing 100038China

Recent years have seen increasing academic interest in exploring the correlation between temperature and crime.However,it is uncertain whether similar long-term trends or seasonality(rather than causal effect)of temper-ature and crime is the major reason for the observed correlation between them.To explore whether there is still a correlation between temperature and crime when long-term trends and seasonal cycles are filtered out,we use the Kalman filter to decompose the time series of temperature and crimes,and then the fast Fourier transform is used to calculate the exact circle of their seasonality separately.Based on that,the box-plot method and linear regression are used to explore the correlation between temperature residuals and crime residuals.The results show that more than half of the crime types have similar seasonal cycles(approximately 1 year)to that of temperature.Moreover,the daily residual analyses show that temperature residuals have a positive correlation with assault and robbery residuals in all cities,whose average slopes are more than 0.1.The other four types of crimes vary greatly from case to case.The temperature residuals show a weak correlation with the residuals of some crime types.

关键词： Time series decomposition Crime Temperature Kalman filter Fast fourier transform

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Clinical features and possible pathogenesis of multiple evanescent white dot syndrome with different retinal diseases and events:a narrative review

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International Journal of Ophthalmology(English edition) 2024年第3期17卷 583-595页

作者： Chun-Li Chen Yi-Zhe Cheng Zhi-Han Zhang ge Wang Xiao-yan Peng Department of Ophthalmology Beijing Tongren HospitalCapital Medical UniversityBeijing 100730China Beijing Ophthalmology and Visual Science Key Laboratory Beijing 100730China State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-sen UniversityGuangzhou 510600Guangdong ProvinceChina

●Multiple evanescent white dot syndrome(MEWDS)is a rare fundus disease,characterized by acute vision loss and visual field defects.Many previous studies have explained the possible pathogenesis and clinical features of primary MEWDS.However,as the number of reported cases increases,secondary MEWDS occurs in other related retinal diseases and injuries,exhibiting some special characteristics.The associated retinal diseases include multifocal choroiditis/punctate inner choroidopathy(MFC/PIC),acute zonal occult outer retinopathy,best vitelliform macular dystrophy,pseudoxanthoma elasticum,and ocular toxoplasmosis.The related retinal injury is laser photocoagulation,surgery,and trauma.Although primary MEWDS often have a self-limiting course,secondary MEWDS may require treatment in some cases,according to the severity of concomitant diseases and complications.Notably,MEWDS secondary to MFC/PIC that is prone to forming choroidal neovascularization and focal choroidal excavation,needs positive treatment with corticosteroids.The possible underlying pathogenesis of secondary MEWDS is the exposure of choroidal antigen after the disruption of Bruch’s membrane.The MEWDS-related features in secondary MEWDS are still evanescent under most circumstances.Its prognosis and treatment depend on the severity of complications.Current studies propose that the etiology is associated with immune factors,including viral infection,inflammation in choroid and Bruch’s membrane,and antigen exposure caused by retinal and/or choroidal insults.More pathogenic studies should be conducted in the future.Accurate diagnosis for secondary MEWDS could benefit patients in aspects of management and prognosis.

关键词： multiple evanescent white dot syndrome punctate inner choroidopathy multifocal choroiditis secondary multiple evanescent white dot syndrome

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Experimental Study on Soot Suppression of Acetylene Diffusion Flame by Acoustic-Excited Oscillation in Rijke-Type Burner

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Journal of Thermal Science 2024年第1期33卷 235-248页

作者： ZHU Yibin GUO Hui SUO yan'ge WU Minle YE yanghui LI Guoneng ZHANG Zhiguo School of Mechanical and Energy Engineering Zhejiang University of Science and TechnologyHangzhou 310023China

This work reports that the flame oscillation induced by acoustic excitation can effectively suppress soot generation in Rijke-type burners.When the acoustic frequency is close to the natural frequency of the burner system,it can produce resonance resulting in intense oscillation of the flame.The relationship between the soot suppression efficiency and the acoustic field of standing wave at different flame positions is discussed.Compared with that under self-excited oscillation,when there is external forced acoustic force introduced to the flame,oscillation combustion occurred in a lager zone in the glass tube.The fundamental cause of different soot suppression efficiency at different positions is that the standing wave acoustic field causes the particles to move at different speeds in different positions of the glass tube.The axial particle velocity difference results in the formation of acoustic vortexes and the change of the flame shape.The high particle velocity causes the air in the glass tube to turn into the turbulent condition and make the flame temperature rise.Simulation results show that the surface growth rate of soot is reduced,while the oxidation rate of soot is enhanced,which result in the soot suppression under acoustic oscillation.This study can provide some reference for the practical application of oscillate combustion in soot suppression.

关键词： soot suppression acetylene diffusion flame acoustic-excited oscillation standing wave

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Remaining Useful Life Prediction Method for Multi-Component System Considering Maintenance:Subsea Christmas Tree System as A Case Study

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China Ocean Engineering 2024年第2期38卷 198-209页

作者： WU Qi-bing CAI Bao-ping FAN Hong-yan WANG Guan-nan RAO Xi ge Weifeng SHAO Xiao-yan LIU Yong-hong CNOOC Safety Technology Services Co. Ltd.Tianjin 300456China College of Mechanical and Electronic Engineering China University of PetroleumQingdao 266580China CNOOC EnerTech Safety&Environmental Protection BranchTianjin 300456China

Maintenance is an important technical measure to maintain and restore the performance status of equipment and ensure the safety of the production process in industrial production,and is an indispensable part of prediction and health management.However,most of the existing remaining useful life(RUL)prediction methods assume that there is no maintenance or only perfect maintenance during the whole life cycle;thus,the predicted RUL value of the system is obviously lower than its actual operating value.The complex environment of the system further increases the difficulty of maintenance,and its maintenance nodes and maintenance degree are limited by the construction period and working conditions,which increases the difficulty of RUL prediction.An RUL prediction method for a multi-omponent system based on the Wiener process considering maintenance is proposed.The performance degradation model of components is established by a dynamic Bayesian network as the initial model,which solves the uncertainty of insufficient data problems.Based on the experience of experts,the degree of degradation is divided according to Poisson process simulation random failure,and different maintenance strategies are used to estimate a variety of condition maintenance factors.An example of a subsea tree system is given to verify the effectiveness of the proposed method.

关键词： remaining useful life Wiener process dynamic Bayesian networks maintenance subsea Christmas tree system

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Kinetic and mechanism of the reaction between Cl and several mono-methyl branched alkanes

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Journal of Environmental Sciences 2024年第1期135卷 474-482页

作者： yan Chen Weigang Wang Junling Li Li Zhou Bo Shi Cici Fan Ke Wang Hao Zhang Hong Li Maofa ge State Key Laboratory for Structural Chemistry of Unstable and Stable Species Beijing National Laboratory for Molecular Sciences(BNLMS)CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China National Engineering Research Center for Flue Gas Desulfurization Department of Environmental Science and EngineeringSichuan UniversityChengdu 610065China College of Chemistry and Materials Science Hebei Normal UniversityShijiazhuang 050024China

Branched alkanes are ubiquitous in the troposphere and play an important role in the chemical processes.In this work,the rate constants and products for the reaction of Cl atoms with 3-methylhexane and 2-methylheptane were measured at room temperature(298±0.2K)and atmospheric pressure using a conventional relative rate method.The rate constants of 3-methylhexane and 2-methylheptane in units of cm~3/(mol·sec)are(3.09±0.31)×10^(-10)and(3.67±0.40)×10^(-10),respectively.Furthermore,the corresponding atmospheric lifetime of the studied branched alkanes with Cl was 6.92-89.90 hours and 5.82-75.69 hours,respectively.The estimated atmospheric lifetimes indicated that the reaction with Cl atoms could be the most important atmospheric degradation pathway for 3-methylhexane and2-methylheptane.Primary gas-phase products of the reactions were identified and quantified,and particle-phase products were also obtained.The atmosphere oxidation mechanism of Cl atoms with 3-methylhexane and 2-methylheptane is proposed.The SOA yields of 3-methylhexane and 2-methylheptane from the reaction of Cl atoms were determined to be7.96%±0.89%and 13.35%±1.50%respectively.Overall,the results reveal that the primary loss process of branched alkanes is the reaction with Cl atoms,which impacts its degradation on a regional scale.

关键词： 3-Methylhexane 2-Methylheptane Chlorine atoms Kinetics Mechanism

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