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Chinese Journal of Aeronautics 2024年第6期37卷 20-37页

作者： Zhiyu li Kaiyuan ZHANG Zhigang li jun.li Institute of Turbomachinery Xi’an Jiaotong UniversityXi’an 710049China

The mid-passage gap is an inevitable structure in a vane passage due to turbine vanes being manufactured *** coolant from this gap is able to prevent hot mainstream ingression and provide cooling protection for the endwall.A novel idea of enlarging the endwall’s coverage area and reducing the endwall’s thermal load by applying the mid-passage gap with variable surface angles is carried out in this *** endwall’s aerothermal and film cooling performances under four mid-passage gap modes at three typical mass flow ratio conditions are numerically *** indicate that under the traditional mid-passage mode,the coolant flows into the mainstream with a perpendicular incidence angle and can’t stick to the ***,cooling failure occurs,and the endwall’s thermal load is badly *** film cooling level at the suction-side endwall is improved when applying the mid-passage gap of a 45surface angle due to the secondary vortex being *** addition,when applying the mid-passage gap of a 135surface angle,the horseshoe vortex is pushed away,and the coverage area at the pressure-side endwall is enlarged *** best film cooling performance is achieved when the upstream surface angle is 135and the downstream surface angle is 45due to the adiabatic film cooling effectiveness being increased at both the pressure-and suction-side *** the mass flow ratio is 1.5%,the coverage area is enlarged by 43%,and the area-averaged adiabatic film cooling effectiveness is increased by 37%,when compared with those under the traditional mid-passage mode.

关键词： Film cooling Heat transfer Surface angle Mid-passagegap Turbinevane endwall

Mechanism of microarc oxidation on AZ91D Mg alloy induced byβ-Mg_(17)Al_(12) phase

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 712-724页

作者： Dajun Zhai Xiaoping li jun Shen College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg *** kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/*** characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic *** was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and *** nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in *** effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge *** MAO coating on Zr-FSP sample had good wettability and corrosion ***,TiO_(2)particles were hardly detected in the coating on TiFSP sample.

关键词： AZ91D Mg alloy microarc oxidation friction stir processing ZrO_(2) TiO_(2) β-Mg_(17)Al_(12)

Vision-based survey method for extraordinary loads on buildings

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Frontiers of Structural and Civil Engineering 2024年第6期18卷 815-831页

作者： Yang li jun CHEN Pengcheng WANG College of Civil Engineering Tongji UniversityShanghai 200092China China United Engineering Co.Ltd. Hangzhou 310052China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Shanghai Key Laboratory of Engineering Structure Safety Shanghai Research Institute of Building Sciences Co.Ltd.Shanghai 200032China

The statistical modeling of extraordinary loads on buildings has been stagnant for decades due to the laborious and error-prone nature of existing survey methods,such as questionnaires and verbal *** study proposes a new vision-based survey method for collecting extraordinary load data by automatically analyzing surveillance *** this purpose,a crowd head tracking framework is developed that integrates crowd head detection and reidentification models based on convolutional neural networks to obtain head trajectories of the crowd in the survey *** crowd head trajectories are then analyzed to extract crowd quantity and velocities,which are the essential factors for extraordinary *** survey areas with frequent crowd movements during temporary events,the equivalent dynamic load factor can be further estimated using crowd velocity to consider dynamic effects.A crowd quantity investigation experiment and a crowd walking experiment are conducted to validate the proposed survey *** experimental results prove that the proposed survey method is effective and accurate in collecting load data and reasonable in considering dynamic effects during extraordinary *** proposed survey method is easy to deploy and has the potential to collect substantial and reliable extraordinary load data for determining design load on buildings.

关键词： load survey extraordinary load live load object detection multiple-object tracking

Investigation on UV-curing Reprocessable Thermosets Bearing Hindered Urea Bonds and Their Composites with Modified Zinc Oxide Nanoparticles

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Chinese Journal of Polymer Science 2024年第6期42卷 751-765页

作者： jun-Hao Zhou li-Ming Tang Key Laboratory of Advanced Materials of Ministry of Education of China Department of Chemical EngineeringTsinghua UniversityBeijing100084China

In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot *** prepolymers were characterized fully by various ***,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and *** from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical ***,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their *** influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then *** composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT *** addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.

关键词： Polyurethane-urea methacrylate Hindered urea bond ZnO nanoparticles Reprocessing UV curing

Prediction models of burst strength degradation for casing with considerations of both wear and corrosion

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Petroleum Science 2024年第1期21卷 458-474页

作者： Jie-li Wang Wen-jun Huang De-li Gao MOE Key Laboratory of Petroleum Engineering China University of PetroleumBeijing102249China State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China

Casing wear and casing corrosion are serious problems affecting casing integrity failure in deep and ultra-deep *** paper aims to predict the casing burst strength with considerations of both wear and ***,the crescent wear shape is simplified into three categories according to common mathematical ***,based on the mechano-electrochemical(M-E)interaction,the prediction model of corrosion depth is built with worn depth as the initial condition,and the prediction models of burst strength of the worn casing and corroded casing are ***,the accuracy of different prediction models is validated by numerical simulation,and the main influence factors on casing strength are *** last,the theoretical models are applied to an ultra-deep well in Northwest China,and the dangerous well sections caused by wear and corrosion are predicted,and the corrosion rate threshold to ensure the safety of casing is *** results show that the existence of wear defects results in a stress concentration and enhanced M-E interaction on corrosion depth *** accuracy of different mathematical models is different:the slot ring model is most accurate for predicting corrosion depth,and the eccentric model is most accurate for predicting the burst strength of corroded *** burst strength of the casing will be overestimated by more than one-third if the M-E interaction is neglected,so the coupling effect of wear and corrosion should be sufficiently considered in casing integrity evaluation.

关键词： Deep well Casing integrity Casing wear Casing corrosion Burst strength

Low-protein diet supplemented with 1% L-glutamine improves growth performance, serum biochemistry, redox status, plasma amino acids, and alters fecal microbiota in weaned piglets

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Animal Nutrition 2024年第2期17卷 144-154页

作者： jun.li jun Bai Ying Yang Zhenlong Wu State Key Laboratory of Animal Nutrition and Feeding Department of Companion Animal Science China Agricultural University

Glutamine, one of the most abundant amino acids in the body, has been shown to exert various beneficial effects in pigs. However, knowledge regarding the role of dietary glutamine in low-protein diet-fed piglets remains scarce. The present study aimed to investigate the effects of different levels of L-glutamine on growth performance, serum biochemistry parameters, redox status, amino acids, and fecal microbiota in low-protein diet-fed piglets. A total of 128 healthy crossbred piglets(Landrace × Yorkshire)were randomly allocated into 4 groups of 4 replicate pens, with 8 piglets per pen. Piglets in the 4 groups were fed with corn and soybean meal-based low-protein diets(crude protein level, 17%) that contained0%, 1%, 2%, and 3% L-glutamine, respectively, for 28 d. Pigs administered 1% L-glutamine had greater body weight on d 28 and average daily gain(ADG, P line content(P < 0.05). Additionally, 1% Lglutamine upregulated the abundance of p＿75＿a5, Clostridium, Lactobacillus, Prevotellaceae＿Prevotella,and Gemmiger in the stool of piglets on d 14, with the Streptococcus lev

关键词： Glutamine Low protein diet Pig Redox status Amino acid Microbiota

Camera,liDAR,and IMU Based Multi-Sensor Fusion SLAM:A Survey

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Tsinghua Science and Technology 2024年第2期29卷 415-429页

作者： jun Zhu Hongyi li Tao Zhang Department of Automation Tsinghua UniversityBeijing 100084China

In recent years,Simultaneous Localization And Mapping(SLAM)technology has prevailed in a wide range of applications,such as autonomous driving,intelligent robots,Augmented Reality(AR),and Virtual Reality(VR).Multi-sensor fusion using the most popular three types of sensors(e.g.,visual sensor,liDAR sensor,and IMU)is becoming ubiquitous in SLAM,in part because of the complementary sensing capabilities and the inevitable shortages(e.g.,low precision and long-term drift)of the stand-alone sensor in challenging *** this article,we survey thoroughly the research efforts taken in this field and strive to provide a concise but complete review of the related ***,a brief introduction of the state estimator formation in SLAM is ***,the state-of-the-art algorithms of different multi-sensor fusion algorithms are *** we analyze the deficiencies associated with the reviewed approaches and formulate some future research *** paper can be considered as a brief guide to newcomers and a comprehensive reference for experienced researchers and engineers to explore new interesting orientations.

关键词： multi-sensor fusion Simultaneous Localization And Mapping(SLAM) navigation localization

A modern survey method for determining live loads based on multi-source and open-access data on the Internet

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Frontiers of Structural and Civil Engineering 2024年第8期18卷 1135-1147页

作者： Chi XU jun CHEN Jie li School of Civil Engineering Tongji UniversityShanghai 200092China The State Key Laboratory on Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

Sufficient survey data are required to describe the stochastic behaviors of live ***,due to manual and on-site operation required by traditional survey methods,traditional surveys face challenges like occupant resistance,high costs,and long implementation *** study proposes a new survey method to access live load data online and *** samples are acquired from multi-source,open-access and dynamically updated data on the *** change intervals,geometrical dimensions and object quantities are obtained from transaction information,building attributes and virtual reality models on real estate websites,*** object weights are collected from commodity information on e-commerce *** integration of the aforementioned data allows for the extraction of necessary statistics to describe a live load *** proposed method is applied to a live load survey in China,covering 20040 m^(2),with around 90000 samples acquired for object weights and load *** survey results reveal that about 70%−80%of the amplitude statistics are attributable to 1/6 of the total object types.

关键词： live load online survey method data acquisition data integration

Unraveling role of double-exchange interaction in electrochemical water oxidation by external magnetic field

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Rare Metals 2024年第1期43卷 289-297页

作者： jun.li jun-Ming li Hong Hong Dong-Xue liu Qing-Qi Cao Dun-Hui Wang National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory for Nanotechnology Nanjing UniversityNanjing 210093China School of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018China

Double-exchange(DE) interaction plays an important role in electrocatalytic oxygen evolution reaction(OER).However,precise achievement of DE interaction often requires foreign dopants or vacancy engineering,leading to destabilization of the catalysts and deterioration of *** contrast,the utilization of environmentally friendly,contactless,and continuously adjustable magnetic fields to study the OER process is profitable to avoid aforementioned interference factors and further elucidate the direct relationship_(0.5)between DE interaction and OER ***,by using cobalt hydroxide carbonate(Co(OH)(CO_(3))·xH_(2)O,CoHC) nanostructures as a proof-of-concept study,external magnetic fields are carefully implemented to verify the role of DE interaction during water oxidation *** studies reveal that external magnetic fields effectively enhance the reaction rate of the catalyst,the overpotential decreases from 386 to 355 mV(100 mA·cm^(-2)),while Tafel slopes drastically decline from 93 to 67 mV·dec^(-1)(1.0 T).Moreover,magnetic field increment exhibits robust *** in situ Raman and impedance measurements under external field,it can be found that magnetic field promotes the electron migration between Co^(2+) and Co^(3+) in the CoHC catalysts with the assistance of DE interactions,thus boosting the OER efficiency.

关键词： Magnetic field Double-exchange(DE)interaction Electrocatalysis Oxygen evolution reaction(OER) Cobalt hydroxide carbonate

Phosphorylated cellulose nanofibers establishing reliable ion-sieving barriers for durable lithium-sulfur batteries

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Journal of Energy Chemistry 2024年第5期92卷 619-628页

作者： Zihao li Pengsen Qian Hongyang li He Xiao jun Chen Gaoran li School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina National Forestry and Grassland Administration Key Laboratory of Plant Fiber Functional Materials Fuzhou 350108FujianChina

The shuttle effect is among the most characteristic and formidable challenges in the pursuit of high-performance lithium-sulfur(li-S)***,phosphorylated cellulose nanofibers(pCNF)are intentionally engineered to establish an ion-sieving barrier against polysulfide shuttling and thereby improve battery *** phosphorylation,involving the grafting of phosphate groups onto the cellulose backbone,imparts an exceptional electronegativity that repels the polysulfide anions from penetrating through the ***,the electrolyte wettability and li^(+)transfer can be significantly promoted by the polar nature of pCNF and the facile li^(+)*** such,rational ion management is realized,contributing to enhanced reversibility in both sulfur and lithium *** a result,li-S cells equipped with the self-standing pCNF separator demonstrate outstanding long-term cyclability with a minimum fading rate of 0.013%per cycle over 1000 cycles at 1 C,and a decent areal capacity of 5.37 mA h cm^(-2) even under elevated sulfur loading of 5.0 mg cm^(-2) and limited electrolyte of 6.0 mL g^(-1).This work provides a facile and effective pathway toward the well-tamed shuttle effect and highly durable li-S batteries.

关键词： lithium-sulfur batteries Cellulose Phosphorylation Ion-sieving Shuttle effect