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Surface integrity and fatigue behavior when turning γ-TiAl alloy with optimized PVD-coated carbide inserts

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Chinese Journal of Aeronautics 2018年第4期31卷 826-836页

作者： Changfeng YAO Jiannan LIN Daoxia WU Junxue ren The Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical University

This paper presents a comprehensive investigation on the effects of tool and turning parameters on surface integrity and fatigue behavior in turning c-Ti Al alloy. The wear of inserts surface, cutting forces, and surface roughness were studied to optimize PVD-coated carbide *** topography, residual stresses, microhardness, and microstructure were analyzed to characterize the surfaces layer under different turning parameters. Surface integrity and fatigue life tests of c-Ti Al alloy were conducted under turning and turning-polishing processes. The results show that compared to CNMG120412-MF4, CNMG120408-SM is more suitable because it obtained low cutting force, surface roughness, and tool wear. With increasing the cutting speed and depth, the depths of the compressive residual stress layer, hardening layer, and plastic deformation layer increased. For turning and turning-polishing specimens, the compressive residual stress was relaxed by less than 20%–30% after 10^7 cycles. The fatigue life of a turning-polishing specimen with ra= 0.15 mm has increased 3 times from that of a turning specimen with ra= 0.43 mm.

关键词： Fatigue behavior Microhardness Residual stress Surface roughness γ-TiAl alloy Tool wear

Modelling analysis embodies drastic transition among global potential natural vegetations in face of changing climate

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Forest Ecosystems 2024年第2期11卷 184-192页

作者： Zhengchao ren Lei Liu Fang Yin Xiaoni Liu School of Earth Science and Resources Chang’an UniversityXi’an710054China Research Center of Ecological Construction and Environmental Conservation in Gansu Province Gansu Agricultural UniversityLanzhou730070China State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing100101China School of Land Engineering Chang’an UniversityXi’an710054China College of Pratacultural Science Gansu Agricultural UniversityLanzhou730070China

Potential natural vegetation(PNV)is a valuable reference for ecosystem renovation and has garnered increasing attention ***,there is limited knowledge on the spatio-temporal distributions,transitional processes,and underlying mechanisms of global natural vegetation,particularly in the case of ongoing climate *** this study,we visualize the spatio-temporal pattern and inter-transition procedure of global PNV,analyse the shifting distances and directions of global PNV under the influence of climatic disturbance,and explore the mechanisms of global PNV in response to temperature and precipitation *** achieve this,we utilize meteorological data,mainly temperature and precipitation,from six phases:the Last Inter-Glacial(LIG),the Last Glacial Maximum(LGM),the Mid Holocene(MH),the Present Day(PD),2030(20212040)and 2090(2081–2100),and employ a widely-accepted comprehensive and sequential classification sy–stem(CSCS)for global PNV *** find that the spatial patterns of five PNV groups(forest,shrubland,savanna,grassland and tundra)generally align with their respective ecotopes,although their distributions have shifted due to fluctuating temperature and ***,we observe an unexpected transition between tundra and savanna despite their geographical *** shifts in distance and direction of five PNV groups are mainly driven by temperature and precipitation,although there is heterogeneity among these shifts for each ***,the heterogeneity observed among different global PNV groups suggests that they may possess varying capacities to adjust to and withstand the impacts of changing *** spatio-temporal distributions,mutual transitions and shift tendencies of global PNV and its underlying mechanism in face of changing climate,as revealed in this study,can significantly contribute to the development of strategies for mitigating warming and promoting re-vegetation in degraded regions worldwide.

关键词： Potential natural vegetation Global warming Vegetation classification Predicted model CSCS

Hot ductility behavior of a Fe-0.3C-9Mn-2Al medium Mn steel

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International Journal of Minerals,Metallurgy and Materials 2021年第3期28卷 422-429页

作者： Yong-jin Wang Shuai Zhao ren-bo Song Bin Hu School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

The hot ductility of a Fe-0.3C-9Mn-2Al medium Mn steel was investigated using a Gleeble3800 thermo-mechanical *** tensile tests were conducted at different temperatures(600-1300℃)under a constant strain rate of 4×10^(−3)s^(−1).The fracture behavior and mechanism of hot ductility evolution were *** showed that the hot ductility decreased as the temperature was decreased from 1000℃.The reduction of area.ra.decreased rapidly in the specimens tested below 700℃,whereas that in the specimen tested at 650℃was lower than 65%.Mixed brittle-ductile fracture feature is reflected by the coexistence of cleavage step,intergranular facet,and dimple at the *** fracture belonged to ductile failure in the specimens tested between 720-1000℃.Large and deep dimples could delay crack *** change in average width of the dimples was in positive proportion with the change in *** wide austenite-ferrite intercritical temperature range was crucial for the hot ductility of medium Mn *** formation of ferrite film on austenite grain boundaries led to strain *** point elongation occurred at the austenite-ferrite intercritical temperature range during the hot tensile test.

关键词： medium Mn steel hot ductility reduction of area fracture behavior microstructure characterization

The next generation of crystal detectors

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radiation Detection Technology and Methods 2018年第1期2卷 7-18页

作者： ren-Yuan Zhu 256-48 HEPCalifornia Institute of TechnologyPasadenaCA 91125USA

Background In high-energy and nuclear physics experiments,total absorption electromagnetic calorimeters made of inorganic crystals are known for their superb energy resolution and detection efficiency for photon and electron measurements.A crystal calorimeter is thus the choice for those experiments where precision measurements of photons and electrons are crucial for their physics *** is also known that the existing crystal detectors are neither bright nor fast enough nor radiation hard enough to survive severe radiation environment expected in future HEP *** detectors have also been proposed to build a homogeneous hadron calorimeter to achieve unprecedented jet mass resolution by duel readout of both Cherenkov and scintillation light,where the development of cost-effective crystal detectors is a crucial issue because of the 100 cubic meters crystal volume *** To develop novel inorganic crystal scintillatorbased detector concepts for future HEP experiments at the energy and intensity *** Optical and scintillation properties of novel inorganic crystal scintillators,such as excitation,emission and transmittance spectra,light output and decay time,are characterized before and after irradiation by ionization dose and *** performance and radiation hardness are compared to the requirements,and feedback is given to the crystal manufacturers for quality *** As a result of this investigation,several inorganic crystal scintillator-based detector concepts are established for future HEP experiments,such as an LSO/LYSO crystalbased total absorption and/or sampling calorimeter concept,a barium fluoride crystal-based very fast crystal calorimeter concept,and a cost-effective inorganic scintillator-based homogeneous hadron calorimeter *** Bright,fast and radiation hard LYSO/LSO crystals may be used for a total absorption *** LYSO/W Shashlik sampling calorimeter will survive the harsh ra

关键词： Crystal Scintillator Calorimeter radiation damage Fast timing Dual readout

A Novel Masking Scheme for SM3 Based MAC

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China Communications 2015年第6期12卷 11-21页

作者： QU Kaige WU Liji WANG An ren Yanting ZHANG Xiangmin Tsinghua National Laboratory for Information Science and Technology(TNList) Tsinghua University Institute of Microelectronics Tsinghua University

The Chinese hash algorithm SM3 is verified to be secure enough,but improper hardware implementation may lead to leakage.A masking scheme for SM3 algorithm is proposed to ensure the security of SM3 based Message Authentication Code(MAC).Our scheme was implemented in hardware,which utilizes hardware oriented secure conversion techniques between boolean and arithmetic *** evaluation based on SAKUra-G FPGA board has been done with 2000 power traces from 2000 random plaintexts with random plaintext masks and random key *** has been verified that the masked SM3 hardware implementation shows no intermediate value leakage as *** masked SM3 hardware can resist first-order correlation power attack(CPA) and collision correlation attack.

关键词： SM3 algorithm masking scheme hardware implementation power analysis boolean and arithmetic masking conversion

Expressions of cellular retinoic acid binding proteins I and retinoic acid receptor-β in the guinea pig eyes with experimental myopia

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International Journal of Ophthalmology(English edition) 2011年第2期4卷 131-136页

作者： Jia Huang Xiao-Mei Qu and ren-Yuan Chu Department of Ophthalmology Eye and ENT Hospital Affiliated to Fudan University Shanghai 200031 China

·AIM:All-trans retinoic acid (ra) is the only extrinsic biochemical candidate known to date that could act as a growth controller,the aim of this study was to investigate the expression cellular retinoic acid binding proteins I (CraBP-I) and retinoic acid receptor-β (raR-β) in retina of the guinea pig eyes with experimental myopia.·METHODS:Ninety guinea pigs aged 14 days were equally and randomly divided into three groups:form deprivation (FD),-5D lens,and *** diffusers for FD were white translucent hemispheres,and-5D lenses were used to introduce hyperopic *** was measured with streak retinoscopy after cycloplegia,and axial length was calculated with Cinescan A/B *** harvested at different time points were used to measure ra level with HPLC and expressions of cellular retinoic acid binding proteins I (CraBP-I) and ra receptor-β (raR-β) were assayed with Western blot and Real-time ***13.0 software was used for statistical analysis.·RESULTS:Up-regulations of CraBP-I and raR-β in ocular tissues correlated with changes in the refractive status and growth rate of the guinea pig eye (P ra started to elevate in 7 days (P raBP-I and raR-β increased by 14 days after visual manipulation (P raR-β,however,increased by 7 days after visual manipulation (P raBP-I and raR-β might lag behind the change of ra.·CONCLUSION:The levels of CraBP-I and raR-β were elevated in retina of the guinea pig eye with experimental *** the progression of experimental myopia,the retinal ra level increased rapidly,and there might be a positive

关键词： retinoic acid CraBP-I raR-β experimental myopia guinea pig

Theoretical and technological exploration of deep in situ fluidized coal mining

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Frontiers in Energy 2019年第4期13卷 603-611页

作者： Heping XIE Yang JU Shihua ren Feng GAO Jianzhong LIU Yan ZHU Institute of Deep Underground Science and Green Energy Shenzhen UniversityShenzhen 518060China Institute of Clean Energy Shenzhen 518060China Sichuan University Chengdu 610065China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology(Beijing)Beijing 100083China Frontier Scientific Research Centre for Fluidlized Mining of Deep Underground Resources China University of Mining and TechnologyXuzhou 221006China China Coal Research Institute Beijing 100013China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221006China China Coal Technology and Engineering Group Co. Ltd.Beijing 100013China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China

Mining industries worldwide have inevitably resorted to exploiting resources from the deep ***,traditional mining methods can cause various problems,e.g.,considerable mining difficulty,environmental degradations,and frequent disastrous *** exploit deep resources in the future,the concept of mining must be reconsidered and innovative new theories,methods,and technologies must be *** effectively acquire coal resources deeper than 2000 m,new theoretical and technological concepts about deep in situ fluidized mining are *** limits of mining depth need to be broken to acquire deep-coal resources in an environmentally friendly,safe,and efficient *** is characterized by‘There are no coal on the ground and no men in the coal mine’.First,this paper systematically explains deep in situ fluidized coal ***,it presents a new theoretical concept,including the theories of mining-induced rock mechanics,three-field visualization,multi-physics coupling for in situ transformation,and in situ mining,transformation and *** also presents key technological concepts,including those of intelligent,unmanned,and fluidized ***,this paper presents a strategic roadmap for deep in situ fluidized coal *** summary,this paper develops new theoretical and technological systems for accomplishing groundbreaking innovations in mining technologies of coal resources in the deep underground.

关键词： coal resource deep in situ fluidized mining theoretical system key technologies strategic roadmap

Acid tolerance of lactate-utilizing bacteria of the order Bacteroidales contributes to prevention of ruminal acidosis in goats adapted to a high-concentrate diet

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Animal Nutrition 2023年第3期14卷 130-140页

作者： Zhongyan Lu Lingmeng Kong Shenhao ren Jorg raschenbach Hong Shen Key Lab of Animal Physiology and Biochemistry College of Veterinary MedicineNanjing Agricultural UniversityNanjingJiangsuChina College of Life Science Nanjing Agricultural UniversityNanjingJiangsuChina Institute of Veterinary Physiology Freie Universitat BerlinBerlinGermany Bioinformatics Center Academy for Advanced Interdisciplinary StudiesNanjing Agricultural UniversityNanjingJiangsuChina

The rapid accumulation of organic acids,particularly lactate,has been suggested as the main cause of ruminal acidosis(ra)for ruminants fed high-concentrate *** research has shown that a gradual shift from low-to high-concentrate diets within 4 to 5 weeks effectively reduces the risk for ***,the mechanisms remain *** this study,20 goats were randomly allocated into four groups(n=5)and fed with a diet containing a weekly increasing concentrate portion of 20%,40%,60%,and 80%over 28 *** d 7,14,21,and 28,one group(named C20,C40,C60,and C80 according to the last concentrate level that they received)was killed and the ruminal microbiome was *** acidosis was not detected in any of the goats during the ***,ruminal pH dropped sharply from 6.2 to 5.7(Prate increased from 40%to 60%.A combined metagenome and meta.ra.scriptome sequencing approach identified that this was linked to a sharp decrease in the abundance and expression of genes encoding nicotinamide adenine dinucleotide(NAD)-dependent lactate dehydrogenase(nLDH),catalyzing the enzymatic conversion of pyruvate to lactate(Prations for nLDH-and iLDH-encoding genes were attributable to bacteria from Clostridiales and Bacteroidales,*** analyzing the gene profiles of 9 metagenome bins(MAG)with nLDH-encoding genes and 5 MAG with iLDH-encoding genes,we identified primary and secondary active transporters as being the major types of sugar transporter for lactate-producing bacteria(LPB)and lactate-utilizing bacteria(LUB),***,more adenosine triphosphate was required for the phosphorylation of sugars to initiate their catabolic pathways in LPB compared to ***,the low dependence of sugar transport systems and

关键词： Ruminal microbiome Ruminal acidosis Acid tolerance Lactate metabolism

Energy‐based analysis of seismic damage mechanism of multi‐anchor piles in tunnel crossing landslide area

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Deep Underground Science and Engineering 2023年第3期2卷 245-261页

作者： Hong Wei Honggang Wu Guojun ren Lin Tang Kang Feng College of Resource and Environment Engineering Guizhou UniversityGuiyangChina China Northwest Research Institute Co.Ltd.of CREC LanzhouChina College of Civil Engineering and Architecture Southwest University of Science and TechnologyMianyangChina

To study the damage mechanism of multi‐anchor piles in tunnel crossing landslide area under earthquake,the damping performance of multi‐anchor piles was *** energy dissipation springs were used as the optimization device of the anchor head to carry out the shaking table comparison test on the reinforced *** Hilbert spectrum and Hilbert marginal spectrum were proposed to analyze the seismic damage mechanism of the multi‐anchor piles,and the peak Fourier spectrum amplitude(PFSA)was used to verify the effectiveness of the *** results show that the seismic energy is concentrated in the high‐frequency component(30-40Hz)of the Hilbert spectrum and the low‐frequency component(12-30 Hz)of the marginal *** indicates that they can be combined with the distribution law of the PFSA to identify the overall and local dynamic responses of the multi‐anchored piles,*** stretchable deformation of the energy‐dissipation springs improves the coordination of the multi‐anchor piles,resulting in better pile *** damage mechanism of the multi‐anchor piles is elucidated based on the energy method:local damage at the top and middle areas of the multi‐anchor piles is mainly caused by the low‐frequency component(12-30 Hz)of the marginal spectrum under the action of 0.15g and 0.20g seismic *** the seismic intensity increases to 0.30g,the dynamic response of the slope is further amplified by the high‐frequency component(30-40 Hz)of the Hilbert energy spectrum,which leads to the overall damage of the multi‐anchor piles.

关键词： Hilbert-Huang transform marginal spectrum multi‐anchor piles seismic damage mechanism