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Numerical investigation of the cavitation noise around a marine propeller focusing on the influence of ventilation

Journal of Hydrodynamics 2023年第4期35卷 630-648页

作者： Shu-jian Lyu Bin Ji Xin-cheng Wang Zhi-wen zhan Da-hai zhang State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China China Ship Development and Design Center National key laboratory on ship Vibration and NoiseWuhan430064China

Cavitation noise around propellers has many adverse *** is still very limited nowadays to inhibit propeller cavitation noise in *** this study,the cavitation noise around a PPTC propeller is simulated using the large eddy simulation(LES)coupled with the porous Ffowcs Williams-Hawkings(PFW-H)*** investigation aims to find a strategy to suppress cavitation noise and analyze the noise suppression *** predicted hydrodynamic results agree well with the experimental data and are utilized in the hydroacoustic *** hydroacoustic results indicate that the pseudo-thickness noise dominates the dominant frequency component of the total cavitation noise due to the effect of cavity evolution,which is one of the reasons why the pseudo-thickness noise dominates the total cavitation noise.A method is found to weaken the cavitation noise through ventilation at the generation location of the sheet cavity(SC).It is worth noting that ventilation inhibits the generation and development of SC by changing the pressure distribution on the suction surface of the blade and pushing away the cavities around the ventilation ***,cavity evolution noise dominates the fluid volume evolution noise under the ventilated cavitating *** significantly attenuates the vapor volume pulsation and thus the cavity evolution noise,which leads to a reduction in pseudo-thickness noise and total cavitation *** ventilation mainly reduces noises at the dominant frequency of the pseudo-thickness noise and the total cavitation noise.

关键词： Cavitation noise ventilation porous Ffowcs Williams-Hawkings(PFW-H)equation large eddy simulation(LES) PPTC propeller

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Pattern Detection in Airborne LiDAR Data Using Laplacian of Gaussian Filter

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Geo-Spatial Information Science 2011年第3期14卷 184-189页

作者： zhan Qingming liang Yubin CAI Ying XIAO Yinghui School of Urban Design Wuhan University 8 South Donghu Road Wuhan 430072 China School of Remote Sensing and Information Engineering Wuhan University 129 Luoyu Road Wuhan 430079 China

Methods for feature detection in laser scanning data have been studied for decades ever since the emergence of the ***,it is still one of the unsolved problems in LiDAR data processing due to difficulty of texture and structure information extraction in unevenly sampled *** paper analyzes the characteristics of Laplacian of Gaussian(LoG) Filter and its potential use for structure detection in LiDAR data.A feature detection method based on LoG filtering is presented and ex-perimented on the unstructured *** method filters the elevation value(namely,z coordinate value) of each point by convo-lution using LoG kernel within its local area and derives patterns suggesting the existence of certain types of ground ob-jects/*** experiments are carried on a point cloud dataset acquired from a neighborhood *** results demonstrate patterns detected at different scales and the relationship between standard deviation that defines LoG kernel and neighborhood size,which specifies the local area that is analyzed.

关键词： laser scanning point cloud feature detection Laplacian of Gaussian filter

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Thermal Error Compensation of the Wear-Depth Real-Time Detecting of Self-Lubricating Spherical Plain Bearings

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Chinese Journal of Mechanical Engineering 2018年第5期31卷 35-47页

作者： zhan-Qi Hu Wei Li Yu-Lin Yang Bing-Li Fan hai-Li Zhou Aviation Key Laboratory of Science and Technology on Generic Technology of Aviation Self-Lubricating Spherical Plain Bearing Yanshan University

The spherical plain bearing test bench is a necessary detecting equipment in the research process of self?lubricating spherical plain bearings. The varying environmental temperatures cause the thermal deformation of the wear?depth detecting system of bearing test benches and then a ect the accuracy of the wear?depth detecting data. However, few researches about the spherical plain bearing test benches can be found with the implementation of the detect?ing error compensation. Based on the self?made modular spherical plain bearing test bench, two main causes of ther?mal errors, the friction heat of bearings and the environmental temperature variation, are analysed. The thermal errors caused by the friction heat of bearings are calculated, and the thermal deformation of the wear?depth detecting sys?tem caused by the varying environmental temperatures is detected. In view of the above results, the environmental temperature variation is the main cause of the two error factors. When the environmental temperatures rise is 10.3 °C, the thermal deformation is approximately 0.01 mm. In addition, the comprehensive compensating model of the thermal error of the wear?depth detecting system is built by multiple linear regression(MLR) and time series analysis. Compared with the detecting data of the thermal errors, the comprehensive compensating model has higher fitting precision, and the maximum residual is only 1 μm. A comprehensive compensating model of the thermal error of the wear?depth detecting system is proposed, which provides a theoretical basis for the improvement of the real?time wear?depth detecting precision of the spherical plain bearing test bench.

关键词： Self?lubricating spherical plain bearing Wear depth Bearing test bench Thermal error Error compensation

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Preparation and characterization of AgSt/AgCl composite grains

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Chinese Chemical Letters 2007年第12期18卷 1521-1524页

作者： Jing Cao hai Li Lin Pei Jie Xia zhan Jun He Department of Chemistry Huaibei Teachers College of Coal Industry Huaibei 235000 China Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100080 China

AgSt/AgC1 composite gains were prepared by adding chloride ions to a mixed solvent in which silver stearate （AgSt） grains were dispersed under the condition of controlled pH value and characterized by SEM, XRD, UV and DSC. The results showed that AgSt/AgC1 composite grains were composed of plateqike AgSt grains with small face-centered cubic AgC1 particles formed on the surface of AgSt. UV spectra displayed a red shift of absorption for AgSt/AgC1 relative to pure AgSt or AgC1. DSC showed a new thermal phase transition of AgSt/AgC1 grains.

关键词： Composite grains Silver stearate Silver chloride pH

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Population Synthesis for the Symbiotic Stars with Main-sequence Accretors

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Chinese Journal of Astronomy and Astrophysics 2006年第4期6卷 447-454页

作者： Guo-liang Lü Chun-Hua Zhu BinWu zhan-Wen Han National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 Graduate School of Chinese Academy of Sciences Beijing 100049 Department of Physics Xinjiang University Urumqi 830046

Using a population synthesis code, we have investigated the formation of symbiotic systems in which the hot component is a main-sequence star that is accreting matter from the cool component via Roche lobe overflow （RLOF）. The RLOF can be divided into two cases： dynamically unstable and stable. In the first case, the birthrate of symbiotic stars is 0.056 yr^- 1 or 0.045 yr^-1 depending on different assumptions; in the stable RLOF case, it is 0.002 yr^-1 or 0.005yr^-1. The number of symbiotic stars with main-sequence accretors and unstable RLOF in our galaxy is about 5, that with stable RLOF is about 60 to 280. Comparison between our results with those of Yungelson et al. shows that symbiotic stars with MS accretors make only a small contribution （ ≤ 8%） to the whole population of symbiotic stars in the Galaxy.

关键词： binaries: symbiotic -- accretion: accretion disks -- stars: evolution -- main-sequence star

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Ru-doped phosphorene for electrochemical ammonia synthesis

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Rare Metals 2020年第8期39卷 874-880页

作者： Jian-Dong Liu Zeng-Xi Wei Yu-hai Dou Yue-zhan Feng Jian-Min Ma Advanced Catalytic Engineering Research Center of the Ministry of Education School of Physics and ElectronicsHunan UniversityChangsha 410082China Centre for Clean Environment and Energy Gold Coast CampusGriffith UniversityGold Coast QLD 4222Australia Key Laboratory of Materials Processing and Mold(Zhengzhou University) Ministry of EducationZhengzhou UniversityZhengzhou 450002China

The electrochemical ammonia synthesis has attracted increasing attention due to its energy saving ***,developing novel electrocatalysts and their mechanism remain great ***,several transition metal(TM)atoms doped on phosphorene were studied as N2 fixation electrocatalysts by using density functional theory(DFT)*** results demonstrate that single Ru atom doped phosphorene shows an excellent catalytic activity for ammonia synthesis via the enzymatic pattern.A small overpotential of 0.696 V is achieved for this *** effect of oxidation in the catalyst was also discussed in our *** deactivates the catalyst,which should be avoided in the *** outcomes offer a novel perspective for single-atom catalytic ammonia synthesis with phosphorene as a substrate.

关键词： Phosphorene Nitrogen reduction reaction Doping Single-atom catalysis Ammonia synthesis

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Federation Boosting Tree for Originator Rights Protection

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Computers, Materials & Continua 2023年第2期74卷 4043-4058页

作者： Yinggang Sun Hongguo zhang Chao Ma hai Huang Dongyang zhan Jiaxing Qu Harbin University of Science and Technology Harbin150040China School of Cyberspace Science Harbin Institute of TechnologyHarbin150001China The Ohio State University Columbus43202USA Heilongjiang Province Cyberspace Research Center Harbin150001China

The problem of data island hinders the application of big data in artificial intelligence model training,so researchers propose a federated learning *** enables model training without having to centralize all data in a central storage *** the current horizontal federated learning scheme,each participant gets the final jointly trained *** solution is proposed for scenarios where participants only provide training data in exchange for benefits,but do not care about the final jointly trained ***,this paper proposes a newboosted tree algorithm,calledRPBT(the originator Rights Protected federated Boosted Tree algorithm).Compared with the current horizontal federal learning algorithm,each participant will obtain the final jointly trained *** can guarantee that the local data of the participants will not be leaked,while the final jointly trained model cannot be *** is worth mentioning that,from the perspective of the participants,the scheme uses the batch idea to make the participants participate in the training in random ***,this scheme is more suitable for scenarios where a large number of participants are jointly ***,a small number of participants will not actually participate in the joint training ***,the proposed scheme is more *** analysis and experimental evaluations show that RPBT is secure,accurate and efficient.

关键词： Federated learning data privacy rights protection decision tree

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Effect of introducing oxygen into ethylene tar pitches on their carbonaceous products

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CHINESE JOURNAL OF CHEMICAL ENGINEERING 2024年第12期76卷 135-146页

作者： Chen, Rongqi zhang, Yongzheng Wang, Yanli Shen, Chunyin zhan, liang Ling, Licheng East China Univ Sci & Technol Minist Educ State Key Lab Green Chem Engn & Ind Catalysis Shanghai Key Lab Multiphase Mat Chem EngnKey Lab Shanghai 200237 Peoples R China

Ethylene tar is a prospective precursor for preparing carbonaceous materials, which is regarded as a representative soft carbon material after carbonization. However, the introduction of oxygen can influence the morphology of the final carbonaceous materials. For the introduction of oxygen, dealkylation and dehydrogenation will be promoted and the molecules can be linked more effectively. For the subsequent carbonization, the biphenyl structures caused by the deoxygenation via the elimination of CO2, as well as the reserved aromatic ether bonds, can facilitate the strong cross-linking, which will restrain the movement of the carbon layers and the formation of the graphitic structures. After the graphitization treatment at 2800 degrees C, the oxidized pitch can lead to short-range ordered and long-range unordered structures, while the sample without oxidation can result in long-range ordered graphitic structures. It can be proved that a simple oxidation-carbonization treatment can transform ethylene tar into hard carbon structures. (c) 2024 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： Fuel Oxidation Ethylene tar pitch Carbonization Hard carbon Chemical processes

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Thermal Fatigue Behavior and Cracking Characteristics of High Si-Mo Nodular Cast Iron for Exhaust Manifolds

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Journal of Iron and Steel Research International 2013年第6期20卷 52-57页

作者： YANG Yun-long CAO zhan-yi LIAN Zhen-song YU hai-xia Key Laboratory of Automobile Materials of Ministry of Education of Department of Education Department of Materials Science and Engineering Jilin University Jilin Vocational College of Industry and Technology

The thermal fatigue cracking behavior of high Si-Mo nodular cast iron （NCI） is investigated by means of optical microscope （OM）, scanning electron microscope （SEM） and energy dispersive spectroscope （EDS）, in order to find a new material used in exhaust manifolds in First Automotive Works （FAW） .Nodular cast irons with silicon content about 4.7% , in combination with up to 1.1% molybdenum , were produced by Jilin University and FAW. The repeated heating / cooling test was performed under cyclic heating at various maximum heating temperatures （Tmax） ranging from 800to 900℃.Experimental results indicate that the thermal fatigue cracking resistance of high Si-Mo NCI decreases with increasing the maximum heating *** periods for crack initiation are 24-36 , 40-50and 70-90times associated with heating temperature of 900 , 850and 800℃ , respectively , when the holding time is about 10min at *** thermal fatigue cracking occurs , the cracking always initiates at the bigger surface of *** major positions of cracks propagation are generally at the eutectic oxide boundary region and the region of the graphite *** the same time , the oxidation may accelerate crack initiation and *** the other hand , micro-crack number varied from large to little because of shielding *** exhaust manifolds , the reasonable working temperature of high Si-Mo NCI is no more than 840℃ by test and analysis.

关键词： thermal fatigue behavior fatigue crack high Si-Mo nodular cast iron exhaust manifold

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Effects of UV-B radiation intensity and timing on epidemiological components of wheat stripe rust

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Journal of Integrative Agriculture 2018年第12期17卷 2704-2713页

作者： WANG Hui QIN Feng CHENG Pei MA zhan-hong WANG hai-guang Department of Plant Pathology China Agricultural UniversityBeijing 100193P.R.China Rizhao Agricultural Bureau of Shandong Province Rizhao 276800P.R.China

Stripe rust caused by Puccinia striiformis f. sp. tritici is an important wheat disease worldwide that is greatly influenced by environmental conditions. Ultraviolet B(UV-B) radiation is one important environmental factor affecting the occurrence and epidemiology of wheat stripe rust. Investigating UV-B radiation effects on the epidemiology of stripe rust may be conducive to monitoring and predicting this disease. In this study, wheat seedlings were exposed to UV-B radiation during different periods under laboratory conditions and radiation effects on epidemiological components of wheat stripe rust were investigated. Results showed that incubation period was shortened, and the infection efficiency, sporulation quantity and disease index increased when UV-B radiation was performed only pre-inoculation. When the UV-B radiation was performed only postinoculation or both pre-and post-inoculation, the incubation period was prolonged, and the infection efficiency, sporulation quantity and disease index were reduced. When healthy wheat seedlings were inoculated using urediospores collected from wheat leaves irradiated by UV-B only post-inoculation or both pre-and post-inoculation, infection efficiency, sporulation quantity and disease index were also reduced. However, in the latter, the disease incubation period did not differ under varying UV-B radiation intensities compared to that when wheat leaves were not treated with UV-B radiation. Overall, the effects of direct exposure of wheat plants to UV-B radiation with different intensities in different periods on epidemiological components of wheat stripe rust were systematically explored, and the results suggest that the effects of UV-B radiation increased gradually with the increase of UV-B radiation intensity. This information provides a basis for monitoring and predicting this disease as well as for conducting further studies on pathogen virulence variation.

关键词： wheat stripe rust UV-B radiation epidemiological component Puccinia striiformis f.sp.tritici

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