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An axisymmetric characteristic model for enhancing prediction of centrifugal compressor characteristics

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Chinese Journal of Aeronautics 2024年第4期37卷 203-215页

作者： Peng REN Xiangjun FANG Zeyu jiao Ying han School of Energy and Power Engineering Beihang UniversityBeijing 100191China Guangdong Key Laboratory of Modern Control Technology Institute of Intelligent ManufacturingGuangdong Academy of SciencesGuangzhou 510070China

Rapid and accurate determination of compressor characteristic maps is essential for the initial design of centrifugal compressors in aircraft power systems. The accuracy of existing methodologies, which rely on combinations of loss models, varies significantly depending on the compressor's geometry and operational range. This variance necessitates substantial experimental or Computational Fluid Dynamics(CFD) data for coefficient calibration. To address this challenge, this study presents an axisymmetric characteristic model for compressor performance assessment. This model incorporates the factors of blade angle, meridional passage area, and the radial deflection angle of meridional streamlines of the compressor. These factors are derived from fundamental aerodynamic equations encompassing mass, momentum, and energy conservation of the compressor. In contrast to conventional one-dimensional approaches, the proposed method reduces the number of loss coefficients and more effectively accounts for the impact of geometric alterations on centrifugal compressor properties. Furthermore, the model reduces dependence on experimental and CFD data. Efficacy of the model is validated using experimental data from four distinct types of centrifugal compressors. Correlation analysis reveals that the model's coefficients can be expressed as functions of the ratio of the Reynolds number to the impeller tip speed. This ratio serves as a characteristic parameter for the design and optimization of centrifugal compressors. Consequently, the proposed method offers an efficient and accurate means for the quick computation of centrifugal compressor characteristics. This is of great significance for improving the efficiency of centrifugal compressors and reducing energy consumption.

关键词： Centrifugal compressor Positive problem Characteristic prediction Aerodynamic characteristic Axisymmetric model

Photoinduced superlubricity on TiO_(2) surfaces

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Friction 2024年第3期12卷 428-438页

作者： Ke han Liran MA Yu tian Jianbin LUO State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Received:16 September 2022/Revised:28 October 2022/Accepted:27 December 2022The author(s)2022.

Superlubricity control is of great interest in both industry and scientific research,and several methods have been proposed to achieve this *** this work,ultraviolet(UV)light was introduced into titanium dioxide(TiO_(2))and silicon nitride(Si_(3)N_(4))tribosystems to accomplish photoinduced *** friction coefficients(COFs)between Si_(3)N_(4) balls and TiO_(2) plates in the mixtures of sulfuric acid(H^(2)SO_(4))solution and glycerol solution were obviously reduced,and the system entered the superlubricity region(COFhan that with UV *** formation of silica(SiO_(2))layers on the surfaces of Si_(3)N_(4) balls and the elastohydrodynamic effects were determined to be fundamental to the low friction in this experiment,and the enhancement of the combination between the TiO_(2) surface and the hydroxy group of glycerol by UV illumination was the key to the photoinduced superlubricity in this *** findings showed one method for achieving superlubricity by introducing a light field that could be further applied to special working conditions.

关键词： light control friction superlubricity glycerol titanium dioxide(TiO_(2))

Analyses on an electronic voltage transformer's failure by its resonance with very fast transient overvoltage and suppression

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High Voltage 2024年第1期9卷 150-162页

作者： Ruoyu han Houda Zhu Qing Chen Hongbin Li Yue Tong Linshan han Yang jiao School of Electrical and Electronic Engineering Huazhong University of Science and TechnologyWuhanChina China Electric Power Research Institute WuhanChina School of Artificial Intelligence and Automation Huazhong University of Science and TechnologyWuhanChina

As voltage measuring devices are widely used in the high voltage power system with a primary-secondary-fusion structure,electronic voltage transformers are directly connected to the primary conductor and would face much more serious electromagnetic environments than general secondary *** a result,they would still experience failures even when general protection measures are adopted to suppress overvoltages'*** address this issue,an innovative method is proposed after analyses are conducted on the resonance between a transformer and an *** this method,an air-cored coil is installed in a transformer to artificially shift its natural frequency and to dodge the high-frequency dominant component of a transient overvoltage,avoiding the aforementioned resonance and suppressing the secondary *** addition,simulations and laboratory tests are conducted to prove this method's validity.

关键词： transient resonance mentioned

Hollow Ni Mo-based nitride heterojunction with super-hydrophilic/aerophobic surface for efficient urea-assisted hydrogen production

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Journal of Energy Chemistry 2024年第8期95卷 428-439,I0009页

作者： Yuying Fan Ying Gu Dongxu Wang Yanqing jiao Aiping Wu Chungui tian Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education of the People’s Republic of ChinaHeilongjiang UniversityHarbin 150080HeilongjiangChina College of Chemistry Chemical Engineering and Resource UtilizationNortheast Forestry UniversityHarbin 150040HeilongjiangChina

Hydrogen evolution reaction(HER)and urea oxidation reaction(UOR)are key reactions of the watercycling associated catalytic process/*** design of catalysts with a super-hydrophilic/aerophobic structure and optimized electron distribution holds great ***,we have designed a threedimensional(3D)hollow Ni/NiMoN hierarchical structure with arrayed-sheet surface based on a onepot hydrothermal route for efficient urea-assisted HER based on a simple hydrothermal *** Ni/NiMoN catalyst exhibits super-hydrophilic/aerophobic properties with a small droplet contact angle of 6.07°and an underwater bubble contact angle of 155.7°,thus facilitating an escape of bubbles from the *** functional theory calculations and X-ray photoelectron spectroscopy results indicate the optimized electronic structure at the interface of Ni and NiMoN,which can promote the adsorption/desorption of reactants and *** virtues combining with a large specific surface area endow Ni/NiMoN with efficient catalytic activity of low potentials of 25 mV for HER and 1.33 V for UOR at10 mA cm^(-2).The coupled HER and UOR system demonstrates a low cell voltage of 1.42 V at 10 mA cm^(-2),which is approximately 209 mV lower than water electrolysis.

关键词： Hydrogen evolution Transition metal nitrides Hollow heterojunctions Urea electrooxidation Super hydrophilic/aerophobic

Influence of Micro/Nano-Ti Particles on the Corrosion Behavior of AZ31-Ti Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 484-498页

作者： Jinchao jiao Jin Zhang Yong Lian Shengli han Kaihong Zheng Fusheng Pan Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 10083China Beijing Key Laboratory for Corrosion Erosion and Surface Technology Beijing 100083China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 404100China

Adding Ti particles to magnesium alloy simultaneously enhances its strength and ***,how these particles influence on Mg alloy’s corrosion performance is seldom *** corrosion behavior of AZ31-Ti composites containing titanium nanoparticles(1.5 and 5 wt%)and micron particles(10 wt%)prepared by powder metallurgical in 3.5 wt%NaCl solution was *** results indicate that Ti particles serve as the primary location for the cathodic hydrogen reduction reaction,resulting in intense galvanic corrosion between the Ti and Mg *** nanoparticles distributed at the interface of the original AZ31 powder were in a discontinuous mesh structure,thus failing to act as a barrier against *** corrosion products with the existence of numerous cracks gradually peel off during the corrosion process and cannot protect the *** average corrosion rate P_(w) of AZ31,AZ31-1.5%Ti,AZ31-5%Ti,and AZ31-10%Ti after 7 days of immersion is 27.55,105.65,283.67,and 99.35 mm/y,***,AZ31-Ti composites can be considered as potential candidates for degradable fracturing ***,it is recommended to improve their corrosion resistance through surface treatment.

关键词： AZ31-Ti composite Nano-Ti Micro-Ti Corrosion behavior Scanning Kelvin probe force microscopy(SKPFM)

A PDGFRβ-targeting nanodrill system for pancreatic fibrosis therapy

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Chinese Chemical Letters 2024年第10期35卷 353-359页

作者： han han Bi-Te Chen Jia-Rong Ding Jin-Ming Si tian-jiao Zhou Yi Wang Lei Xing Hu-Lin Jiang State Key Laboratory of Natural Medicines Department of PharmaceuticsChina Pharmaceutical UniversityNanjing 210009China College of Pharmacy .Yanbian UniversityYanji 133002China Department of Nephrology Changhai HospitalNaval Medical UniversityShanghai 200433China

Activated pancreatic stellate cells(PSCs)are the main source of collagen layer deposition and the key target in pancreatic ***,no effective treatment specific to pancreatic fibrosis clinically,owing to the drug accumulation blocked by the collagen barrier and thus it is difficult to inhibit activated PSCs ***,a PSCs-targeting nano-system based on“nanodrill”strategy(LA-PC)was designed to enhance the accumulation of all-trans retinoic acid(ATRA)in PSCs,relying on the platelet-derived growth factor receptor beta(PDGFRβ)-targeting peptide(p PB:C*SRNLIDC*)and collagenase(Col).After being injected into fibrotic mice via tail vein,the Col modified on LA-PC can remove the excess collagen layer,and the drug delivery efficiency through pPB targeting peptide was more than 5 times higher than that of free ATRA,as well as the degree of fibrosis significantly ***,this nano-system effectively inhibited platelet-derived growth factor subunit B(PDGF-BB)/PDGFRβaxis on PSCs via a down-regulated extracellular signal-regulated protein kinase(ERK)pathway,and accordingly reduced the level of ***,the smart platform provided a promising strategy for the treatment of pancreatic fibrosis to achieve the precise regulation of PSCs.

关键词： Pancreatic fibrosis Pancreatic stellate cells Liposome PDGFRβ pPB peptide

Analysis on unit maximum capacity of orthogonal multiple watermarking for multimedia signals in B5G wireless communications

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Digital Communications and Networks 2024年第1期10卷 38-44页

作者： Mianjie Li Senfeng Lai jiao Wang Zhihong tian Nadra Guizani Xiaojiang Du Chun Shan School of Electronics and Information Guangdong Polytechnic Normal UniversityGuangzhou510665China Cyberspace Institute of Advanced Technology Guangzhou UniversityGuangzhou510006China Schoolof Electrical Engineering and Computer Science Washington State UniversityPullmanWA99164USA Department of Computer and Information Science Temple UniversityPhiladelphiaPA19122USA

Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication *** that intelligent applications to B5G wireless communications will involve security issues regarding user data and operational data,this paper analyzes the maximum capacity of the multi-watermarking method for multimedia signal hiding as a means of alleviating the information security problem of *** multiwatermarking process employs spread transform dither *** the watermarking procedure,Gram-Schmidt orthogonalization is used to obtain the multiple spreading ***,multiple watermarks can be simultaneously embedded into the same position of a multimedia ***,the multiple watermarks can be extracted without affecting one another during the extraction *** analyze the effect of the size of the spreading vector on the unit maximum capacity,and consequently derive the theoretical relationship between the size of the spreading vector and the unit maximum capacity.A number of experiments are conducted to determine the optimal parameter values for maximum robustness on the premise of high capacity and good imperceptibility.

关键词： B5G Multimedia information security Spread transform dither modulation Spreading vector measurement Unit maximum capacity

Hydration lubrication modulated by water structure at TiO2–aqueous interfaces

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Friction 2024年第4期12卷 591-605页

作者： Pingsu MA Yuan LIU Ke han Yu tian Liran MA State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

The nature of solid-liquid interfaces is of great significance in *** advances have been made in lubrication based on hydration ***,a detailed molecular-level understanding is still ***,we investigated water molecule behaviors at the TiO2-aqueous interfaces by the sum-frequency generation vibrational spectroscopy(SFG-VS)and atomic force microscope(AFM)to elucidate the fundamental role of solid-liquid interfaces in *** contributions of water structures and hydration effects were revealed,where water structures played the dominant role in lubrication for TiO2 surfaces of varying hydrophilicity,while hydration effects dominated with the increasing of ion *** lubrication is observed on the initial TiO2 surfaces with strongly H-bonded water molecules compared to the hydrophilic TiO2 surfaces with more disordered *** stable ordered water arrangement with strong hydrogen bonds and the shear plane occurring between the ordered water layer and subsequent water layer may play a significant role in achieving lower *** adsorbed hydrated molecules with the increasing ionic concentration perturb ordered water but lead to the enhancement of hydration effects,which is the main reason for the improved lubrication for both *** work provides more insights into the detailed molecular-level understanding of the mechanism of hydration lubrication.

关键词： hydration lubrication interfacial water structures hydration effects titanium dioxide(TiO2)

Vermicompost:In situ retardant of antibiotic resistome accumulation in cropland soils

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Journal of Environmental Sciences 2024年第7期141卷 277-286页

作者： Meirui Mu Fengxia Yang Bingjun han Guisheng tian Keqiang Zhang Agro-Environmental Protection Institute Ministry of Agriculture and Rural AffairsTianjin 300191China Key Laboratory of Low-carbon Green Agriculture in North China Ministry of Agriculture and Rural Affairs P.R.ChinaBeijing 10083China Wuxue City Agriculture and Rural Bureau Wuhan 435400China

The dissemination of antibiotic resistance genes(ARGs)in soil has become a global environmental *** is gaining prominence in agricultural practices as a soil amendment to improve soil ***,its impact on soil ARGs remains unclear when it occurs in *** comprehensively explored the evolution and fate of ARGs and their hosts in the field soil profiles under vermicompost application for more than *** application increased several ARG loads in soil environment but decreased the high-risk bla-ARGs(bla_(ampC),bla_(NDM),and bla_(GES-1))by log(0.04-0.43).ARGs in soil amended with vermicompost primarily occurred in topsoil(approximately 1.04-fold of unfertilized soil),but it is worth noting that their levels in the 40-60 cm soil layer were the same or even less than in the unfertilized *** microbial community structure changed in soil profiles after vermicompost *** application altered the microbial community structure in soil profiles,showing that the dominant bacteria(i.e.,Proteobacteria,Actinobacteriota,Firmicutes)were decreased 2.62%-5.48%with the increase of soil depth.A network analysis further revealed that most of ARG dominant host bacteria did not migrate from surface soil to deep *** particular,those host bacteria harboring high-risk bla-ARGs were primarily concentrated in the surface *** study highlights a lower risk of the propagation of ARGs caused by vermicompost application and provides a novel approach to reduce and relieve the dissemination of ARGs derived from animals in agricultural production.

关键词： Vermicompost application Antibiotic resistance genes Vertical migration Soil profile Agricultural soils