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Interfacial friction effects on sealing performances of elastomer packer

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Petroleum Science 2024年第3期21卷 2037-2047页

作者： Peng-Cheng Wang Ming-hui Chen Jim Jenkinson Yong-Xin Song li Sun Department of Mechanical Engineering University of HoustonHoustonTX77024USA Guren Nanomaterials Suzhou215127JiangsuChina Department of Marine Engineering Dalian Maritime UniversityDalian116026LiaoningChina

Elastomer sealing performance is of critical importance for downhole tools application including the use of fracturing(Frac)plugs during multi-stage hydraulic *** practice sealing performances of such plugs are normally evaluated through pressure tests,and in numerical simulation studies,maximum contact stress,average contact stress and contact length data are used to determine sealing quality between a packer and *** previous studies,the impact of friction forces on sealing performance is often *** work aims to fill this knowledge gap in determining the influence of friction forces on elastomer packer sealing *** first determined the most appropriate constitutive hyperelastic model for the elastomers used in frac *** we compared analytical calculation results with Finite Element Analysis simulation using a simplified tubular geometry and showed the significant influences on interfacial friction on elastomer packer stress distribution,deformation,and contact stress after *** the demonstration of validity of FEA method,we conducted systematic numerical simulation studies to show how the interfacial friction coefficients can affect the maximum contact stress,average contact stress,contact stress distribution,and maximum mises stress for an actual packer used in plug *** addition,we also demonstrated how the groove in a packer can affect packer deformation and evolvement during setting with the consideration of interfacial *** study underscores the critical role that friction forces play in Frac plug performance and provides a new dimension for optimizing packer design by controlling interfacial interactions at the packer contact surfaces.

关键词： Elastomer seal Friction Sealing performance Contact stress

Mitigation of Deane and Hamill phenomenon in gallium nitride high-voltage power supply for electric propulsion system application

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High Voltage 2024年第1期9卷 252-265页

作者： Minghai Dong hui li Shan Yin Kye Yak See Yingzhe Wu Xiong Xin School of Aeronautics&Astronautics University of Electronic Science and Technology of ChinaChengduChina School of Electrical&Electronic Engineering Nanyang Technological UniversitySingaporeSingapore School of Automation Engineering University of Electronic Science and Technology of ChinaChengduChina Innoscience(Shenzhen)Semiconductor Co.Ltd. ShenzhenChina

The step-up resonant converters are widely adopted to provide high voltage in kV-level for electric propulsion system due to their high efficiency,low mass,modularisation,and high-power *** bipolar Cockcroft-Walton voltage multiplier(BiCWVM)is a major circuit that steps up the voltage in the resonant ***,the diode nonlinearity in BiCWVM can introduce self-sustained quasi-periodic oscillations in the voltage and current waveforms,which is commonly known as the Deane and Hamill(DH)*** oscillation can lead to higher magnetic loss and control failure,and it is more likely to present in the gallium nitride-based converter due to the highfrequency *** authors aim to investigate and mitigate the DH phenomenon systematically so that proper mitigation can be *** facilitate the investigation,the circuit before the BiCWVM in the converter is derived and modelled as a voltage source v_(m)and a series inductor L_(sy).Also,the reverse recovery process of the diode in the BiCWVM can be represented by a piecewise-linear(PWL)model,with the simplified circuit and PWL model,the relationship between voltage and current under different operating conditions can be determined with *** relationship allows to understand the mechanism of diode reverse recovery in BiCWVM that leads to DH ***,a hybrid-/full-silicon carbide(SiC)design is proposed to mitigate the DH phenomenon,which is verified experimentally for a 300-kHz,5-W,20-V/1.5-kV GaN-based step-up resonant converter.

关键词： power resonant high

CO_(2) corrosion of X80 steel welded joints under micro-turbulence induced by welding reinforcement height

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Journal of Iron and Steel Research(International) 2024年第4期31卷 1015-1032页

作者： Xiao-hui Dou Bin li Zong-hao He Xin-wei Zhang Da-lei Zhang Yan li School of Materials Science and Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina School of Energy and Power Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina

Corrosion failure accidents owing to flow erosion and pipeline corrosion frequently occur during *** welding reinforcement height(WRH)can induce locally micro-turbulent flow field,which aggravates local corrosion of welded joints.A high wall shear stress(WsS)experimental setup was established to conduct the online electrochemical corrosion *** influence of WRH sizes on local corrosion of welded joints was studied at different flow *** electrochemical signals of the local corrosion of X80 welded joints at different flow rates were monitored in real time using electrochemical impedance spectroscopy and wire beam *** addition,the corrosion products composition and properties were *** results show that the micro-turbulent flow fields induced by the WRHs can enhance ion mass transfer near the welded *** corrosion products on the WRH surface also present different microscopic morphologies at different flow *** strong flow fields,the locally enhanced wsS can peel off the dense corrosion product partially,leading to the electrochemical distribution of large cathode and small anode,which accelerates the occurrence and development processes of the local corrosion of welded *** scientific guidelines for the corrosion protection of long-distance oil and gas pipelines can be potentially provided.

关键词： X80 steel welded joint Welding reinforcement height Micro-turbulence CO_(2)corrosion-Ion mass transfer

The Impact of High-standard Free Trade Areas on the Diversification of China's Export Products: Expanding Market or Intensifying Competition?

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China & World Economy 2024年第4期32卷 33-67页

作者： Zhaobin Fan Ruimin Bian hui li International Business School Jinan UniversityChina School of Management Jinan UniversityChina School of Mathematics University of BirminghamUK

In the context of China's efforts to establish a global network of free trade areas and diversify its export products, this study explores the impact of trade agreement depth on China's export diversification. Building upon a trade model with multiproduct firms, we discover that the effect of trade agreement depth on export diversification is multifaceted, depending on the relative magnitude of the “market expansion effect” and the “competition intensification effect.” Through empirical analysis of China's exports to 132 countries (or regions) from 2000 to 2015, we find that the deepening of trade agreements affected China's export diversification negatively. This negative correlation was predominantly due to the similarity in comparative advantages between China and its trade partners, leading to the “competition intensification effect” overshadowing the “market expansion effect.” We also note that “natural” agreements, when deepened, were more likely to affect China's export diversification adversely than their “non-natural” counterparts. Moreover, as export diversification increased, the marginal impact of deepening trade agreements exhibited an inverted U-shaped trajectory.

关键词： export product diversification export similarity high-standard free trad areas trade agreement depth

Base editor-mediated large-scale screening of functional mutations in bacteria for industrial phenotypes

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Science China(life Sciences) 2024年第5期67卷 1051-1060页

作者： Yaomeng Yuan Xihao liao Shuang li Xin-hui Xing Chong Zhang MOE Key Laboratory for Industrial Biocatalysis Institute of Biochemical EngineeringDepartment of Chemical EngineeringTsinghua UniversityBeijing 100084China Institute of Biopharmaceutical and Health Engineering Tsinghua Shenzhen International Graduate SchoolShenzhen 518055China Institute of Biomedical Health Technology and Engineering Shenzhen Bay LaboratoryShenzhen 440300China Center for Synthetic and Systems Biology Tsinghua UniversityBeijing 100084China

Base editing,the targeted introduction of point mutations into cellular DNA,holds promise for improving genome-scale functional genome screening to single-nucleotide *** efforts in proka.yotes,however,remain confined to loss-of-function screens using the premature stop codons-mediated gene inactivation library,which falls far short of fully releasing the potential of base ***,we developed a base editor-mediated functional single nucleotide variant screening pipeline in Escherichia *** constructed a library with 31,123 sgRNAs targeting 462 stress response-related genes in ***,and screened for adaptive mutations under isobutanol and furfural selective *** by the screening results,we successfully identified several known and novel functional *** pipeline might be expanded to the optimization of other phenotypes or the strain engineering in other microorganisms.

关键词： base editor high-throughput large-scale screening Escherichia coli functional mutation

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Higher intakes of lysine,threonine and valine are inversely associated with non-alcoholic fatty liver disease risk:a community-based case-control study in the Chinese elderly

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Food Science and Human Wellness 2024年第1期13卷 191-197页

作者： Xueqi li Wenjun Ma Ting Yang Chong Wang Wei Zhang hui li Ting Zhao Xiaofei Guo Institute of Nutrition&Health School of Public HealthQingdao UniversityQingdao 260071China Affiliated Hospital of Qingdao University Qingdao 260071China

The associations of individual amino acid with non-alcoholic fatty liver disease(NAFLD)risk remained *** present study aimed to investigate the associations between the two in the Chinese ***:A community-based health check-up program was conducted in Qingdao,*** was diagnosed by ultrasonography accompanied by epidemiological *** dietary intakes of amino acids were investigated with 3-day,24-h dietary records and calculated by Nutrition Calculator *** cubic spline model was used to evaluate a nonlinear relationship between amino acid intake and NAFLD ***:400 NAFLD subjects were identified,and 400 participants were randomly selected as controls and matched by gender and age(±3 years)Dose-response analysis showed that 1000 mg increment of aromatic amino acids(AAAs)was associated with reduced 16%risk of *** increments of 750 mg/d threonine,950 mg/d valine,or 1700 mg/d lysine were associated with a 20%reduction in the NAFLD risk(all P for linearity<0.05).Conclusion:The present study demonstrated that the dietary increases in milk,eggs and deep-sea fish,which are rich in the amino acids,might contribute to protecting against NAFLD in the elderly.

关键词： Amino acid Non-alcoholic fatty liver disease Senior citizen Dose-response analysis

Tuning heterogeneous microstructures to enhance mechanical properties of nano-TiN particle reinforced Haynes 230 composites by laser powder bed fusion

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Rare Metals 2024年第9期43卷 4548-4565页

作者： Wen-Jie liu hui li Qian-Xing Yin He-Jun Du School of Power and Mechanical Engineering Wuhan University The Institute of Technological Sciences Wuhan University School of Mechanical&Aerospace Engineering Nanyang Technological University

Laser powder bed fusion(LPBF) is considered to be one of the most promising additive manufacturing technologies for producing components with geometries and high geometrical precision that are unattainable by traditional technologies. The superalloy exhibits exceptional mechanical and high-temperature performances,rendering it a prime candidate for advanced aero-engine applications. Despite the high demand for LPBF-manufactured superalloys, the superalloy is one of the materials manufactured difficultly by LPBF due to their large laser absorptivity fluctuation, poor molten pool stability and sharp temperature gradient. Hence, superalloys are characterized by severe pores, undesirable coarse columnar grains and poor mechanical properties. In this work, the effect of nano-Ti N particles on defects, molten pool characteristics and microstructure and performance of the composites were investigated. The 4.5 wt% Ti N/Haynes230 samples exhibited exceptional nanohardness and elastic modulus with maximum values reaching 5.53 GPa and 240.03 GPa, respectively. These superior mechanical properties were attributed to the combined effects of spatter and gas pore inhibition, grain refinement and duplex nanophases strengthening. Moreover, the stability of molten pool was enhanced, and spatter was effectively suppressed by adding nano-Ti N particles, while grain refinement and columnar to equiaxed transitions were promoted. Furthermore, the matrix exhibited a high dislocation density due to a significant hindrance of dislocation movement caused by massive nano-phases(e.g., Ti N and M23C6), resulting in the formation of extensive dislocation tangles and *** work offers novel insights into the role of nanoparticles reinforced superalloy composites by LPBF.

关键词： Composites Laser powder bed fusion Mechanical properties Microstructure Molten pool characteristics

Super-high bed sintering for iron ores:problems ascertainment

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Journal of Iron and Steel Research(International) 2024年第5期31卷 1063-1070页

作者： liang-ping Xu hui-bo liu Yu-chao Zhao Qiang Zhong Zhong-lin Dong Guang-hui li Tao Jiang School of Minerals Processing and Bioengineering Central South UniversityChangsha410083HunanChina

Super-high bed sintering process is an important development direction of iron ore sintering for its lower emission and higher ***,there is a lack of deep understanding of the uneven quality of super-high bed sintering products,and the deterioration of reduction disintegration performance,the thickening of hearth layer and the reduction in energy-saving effect are perplexing enterprises and *** ascertain the problems of super-high bed sintering,ten sintering machines with the areas of 265,280,360,550 and 660 m^(2)and bed depth above 900 mm were sampled and *** results showed that problems were mainly shown in the unevenness of chemical composition,macrostructure,mechanical strength and metallurgical *** chemical composition exhibits severe segregation in both horizontal and vertical directions,with basicity segregation reaching as high as *** uneven macrostructure of sinter is reflected in a 10%difference in porosity and mechanical strength increase in 16%–19%along the vertical *** reducibility and reduction disintegration performance gradually deteriorate along the bed depth,with a difference of 10.5%in reducibility and 7.3%in RDI−0.5 mm(reduction disintegration index of sinter with size smaller than 0.5 mm).

关键词： Super-high bed sintering Uneven sinter performance Segregation Agglomeration Iron ore

Single-cell transcriptomic atlas of goat ovarian aging

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Journal of Animal Science and Biotechnology 2024年第1期15卷 146-161页

作者： Dejun Xu Shuaifei Song Fuguo Wang Yawen li Ziyuan li hui Yao Yongju Zhao Zhongquan Zhao Chongqing Key Laboratory of Herbivore Science College of Animal Science and TechnologySouthwest UniversityChongqing 400715China

Background The ovaries are one of the first organs that undergo degenerative changes earlier in the aging process,and ovarian aging is shown by a decrease in the number and quality of ***,little is known about the molecular mechanisms of female age-related fertility decline in different types of ovarian cells during aging,especially in ***,the aim of this study was to reveal the mechanisms driving ovarian aging in goats at single-cell *** For the first time,we surveyed the single-cell transcriptomic landscape of over 27,000 ovarian cells from newborn,young and aging goats,and identified nine ovarian cell types with distinct gene-expression *** enrichment analysis showed that ovarian cell types were involved in their own unique biological processes,such as Wnt beta-catenin signalling was enriched in germ cells,whereas ovarian steroidogenesis was enriched in granulosa cells(GCs).Further analysis showed that ovarian aging was linked to GCs-specific changes in the antioxidant system,oxidative phosphorylation,and ***,we identified a series of dynamic genes,such as AMH,CRABP2,THBS1 and TIMP1,which determined the fate of ***,FOXO1,SOX4,and HIF1A were identified as significant regulons that instructed the differentiation of GCs in a distinct manner during ovarian *** This study revealed a comprehensive aging-associated transcriptomic atlas characterizing the cell typespecific mechanisms during ovarian aging at the single-cell level and offers new diagnostic biomarkers and potential therapeutic targets for age-related goat ovarian diseases.

关键词： Goat Granulosa cells Ovarian aging Single-cell transcriptomic