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Level excursion analysis of probabilistic quasibrittle fracture

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science China(Technological sciences) 2020年第7期63卷 1141-1153页

作者： LE Jia-liang Department of Civil Environmentaland Geo-EngineeringUniversity of MinnesotaMinneapolis 55455USA

It has widely been acknowledged that no structures can be designed to be risk free, and therefore reliability analysis plays.an essential role in the design of engineering structures. The recent focus has been placed on structures made of brittle heterogenous.a.k.a. quasibrittle) materials, such as ceramics, composites, concrete, rock, cold asphalt mixture, and many more at the micros.ale. This paper presents.a level excursion model for the analysis of probabilistic failure of quasibrittle structures, in which the failure s.atistics is calculated as.a first pas.age probability. The model captures both the s.atial randomness of local material resis.ance and the random stress field induced by microstructures(e.g. randomly distributed flaws). The model represents.a generalization of the classical weakest-link model at the continuum limit and it recovers the classical Weibull distribution as.an asymptotic distribution function. The paper discusses two applications of the model. The model is first applied to the strength distribution of polycrys.alline silicon(poly-si) MEMs specimens. It is shown that the model agrees well with the experimentally measured strength distributions of poly-si MEMs specimens of different sizes. The model predicts.a complete size effect curve of the mean structural strength transitioning from a vanishing size effect at the s.all-size limit to the classical Weibull size effect at the large-size limit. The second application is concerned with the left tail of strength distribution of quasibrittle *** taking into account both random stress.and strength fields, the model is used to investigate the origin of the power-law tail distribution of structural strength.

关键词： quasibrittle materials strength distribution first pas.age analysis Weibull s.atistics size effect

Chain Flexibility and Connectivity:The Uniqueness of Polymer Crys.allization

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Chinese Journal of Polymer science 2023年第1期41卷 7-13页

作者： liang-Bin Li National synchrotron Radiation Laboratory CAS Key Laboratory of Soft Matter ChemistryAnhui Provincial Engineering Laboratory of Advanced Functional Polymer FilmUniversity of Science and Technology of ChinaHefei230026China

Theory of polymer crys.allization is listed as one of the top ten current challenges in polymer *** the uniqueness of polymer crys.allization should be the first step to s.arch for the roadmap for targeting this *** flexibility and connectivity are two peculiar characteristics of polymers,which differentiate their dynamics.and structures from that of s.all *** uniqueness of polymer crys.allization must also stem from these two peculiar characteristics,which,however,has not been attracted significant attention.A local structure order may be essential in assisting the transformation of flexible chain to rigid segment with conformational *** entanglement pressure and entanglement free energy may help to unders.and how entanglement affect nucleation in polymer network and why the interlamellar amorphous layer always.accompany the formation of crys.al *** recommendations will be given for future study.

关键词： Polymer crys.allization Chain flexibility Chain connectivity Nucleation

Gravidynamics,spinodynamics.and electrodynamics within the framework of gravitational quantum field theory

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science China(Physics,Mechanics & Astronomy) 2023年第6期66卷 148-190页

作者： Yue-liang Wu International Centre for Theoretical Physics.as.a-Pacific University of Chinese Academy of SciencesBeijing 100190China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China Taiji Laboratory for Gravitational Wave Universe(Beijing/Hangzhou) University of Chinese Academy of SciencesBejing 100049China school of Fundamental Physics.and Mathematical sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou310024China

By noticing the fact that the charged leptons.and quarks in the s.andard model are chirality-based Dirac spinors since their weak interaction violates maximally parity symmetry though they behave as Dirac fermions in electromagnetic interaction,we show that such a chirality-based Dirac spinor possesses not only electric charge gauge symmetry U(1)but also inhomogeneous spin gauge symmetry Ws(1,3)=sP(1,3)?W1,3,which reveals the nature of gravity and *** gravitational force and spin gauge force are governed by the gauge symmetries W1,3and sP(1,3),respectively,and a biframe s.acetime with globally fiat Minkowski s.acetime as base s.acetime and locally fiat gravigauge s.acetime as.a fiber is described by the gravigauge field through emergent non-commutative *** gauge-geometry duality and renormalizability in gravitational quantum field theory(GQFT)are carefully discussed.A detailed analysis.and systematic investigation on gravidynamics.and spinodynamics.as well as electrodynamics.are carried out within the framework of GQFT.A full discussion on the generalized Dirac equation and Maxwell equation as well as Einstein equation and spin gauge equation is made in biframe *** effects of gravidynamics.as extension of general relativity are particularly *** dynamic equations of basic fields.are demonstrated to preserve the spin gauge covariance and general coordinate covariance due to the spin gauge symmetry and emergent general linear group symmetry GL(1,3,R),so they hold naturally in any spinning reference frame and motional reference frame.

关键词： inhomogeneous spin gauge symmetry locally flat gravigauge s.acetime gravitational relativistic quantum mechanics with generalized Dirac equation gravidynamics with generalized Einstein equation generalized Maxwell equation in any motional and spinning reference frame

Formula of Overtopping Discharge of Vertical s.awall with A Form similar to solitary Wave Function

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China Ocean Engineering 2022年第5期36卷 802-807页

作者： LI Xiao-liang school of Naval Architecture&Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

An empirical formula to predict overtopping discharge of vertical wall is presented,in which an expression similar to the solitary wave function is proposed to describe the rule of the influence of relative water *** formula is derived from performing an investigation to the well-known overtopping graphs of Goda,and for the sake of interest,the process of the derivation is *** make clear the formula’s performance,relevant test datasets in the CLAsH database are extracted to examine the error levels of the *** a result,an overall good agreement has been found between the predictions of the formula and the extracted datasets in a wide range outside the extreme s.allow region,i.e.,the range of relative water depth s.aller than 0.6,in which the water depth near the wall is so s.allow that nearly all the incoming waves have been broken before reaching the wall.

关键词： overtopping discharge formula vertical wall Goda graph

Multifaceted role of one-carbon metabolism on immunometabolic control and growth during pregnancy, lactation and the neonatal period in dairy cattle

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Journal of Animal science and Biotechnology 2021年第1期12卷 82-109页

作者： Danielle N.Coleman Abdulrahman s.alharthi Yusheng liang Matheus Gomes Lopes Vincenzo Lopreiato Mario Vailati-Riboni Juan J.Loor Department of Animal sciences Division of Nutritional SciencesUniversity of IllinoisUrbanaIL 61801USA .2Department of Animal Production College of Food and Agriculture SciencesKing Saud UniversityRiyadh 11451Saudi Arabia .3Department of Animal sciences Food and NutritionFaculty of AgricultureFood and Environmental ScienceUniversitàCattolica del Sacro Cuore29122 PiacenzaItaly.

Dairy cattle undergo dramatic metabolic, endocrine, physiologic and immune changes during the peripartal period largely due to combined increases in energy requirements for fetal growth and development, milk production, and decreased dry matter intake. The negative nutrient balance that develops results in body fat mobilization,subsequently leading to triacylglycerol(TAG) accumulation in the liver along with reductions in liver function,immune dysfunction and a s.ate of inflammation and oxidative stress. Mobilization of muscle and gluconeogenesis.are also enhanced, while intake of vitamins.and minerals is decreased, contributing to metabolic and immune dysfunction and oxidative stress. Enhancing post-ruminal supply of methyl donors is one approach that may improve immunometabolism and production synergistically in peripartal cows. At the cellular level, methyl donors(e.g. methionine, choline, betaine and folic acid) interact through one-carbon metabolism to modulate metabolism,immune responses.and epigenetic events. By modulating those pathways, methyl donors may help increase the export of very low-density lipoproteins to reduce liver TAG and contribute to antioxidant synthesis to alleviate oxidative stress. Thus, altering one-carbon metabolism through methyl donor supplementation is.a viable option to modulate immunometabolism during the peripartal period. This review explores.available data on the regulation of one-carbon metabolism pathways in dairy cows in the context of enzyme regulation, cellular sensors.and signaling mechanisms that might respond to increased dietary supply of specific methyl donors. Effects of methyl donors beyond the one-carbon metabolism pathways, including production performance, immune cell function,mechanistic target or rapamycin signaling, and fatty acid oxidation will also be highlighted. Furthermore, the effects of body condition and feeding system(total mixed ration vs. pasture) on one-carbon metabolism pathways.are explored. Poten

关键词： Epigenetics Immune system Metabolism Methyl donor Transition period

Al_2O_3 PARTICLE REINFORCED COPPER MATRIX COMPOsITE UsING FOR CONTINUOUs CAsTING MOULD

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Acta Metallurgica sinica(English Letters) 1999年第5期12卷 782-786页

作者： s.H.liang and Z.K.Fan The Department of Material and Engineering, Xi’an University of Technology, Xi’an 710048, China Xi'an Univ of Technology Xi'an China

A kind of Cu base composite reinforced by 0 1μm Al 2O 3 particles were prepared by hot pressing and sintering process for steel continuous casting mould. The microstructure and properties were studied. The results show that the Al 2O 3 particle distribution is uniform, and the particles refine the grain size. The tensile fracture is.a mixture of quasi cleavage and dimple due to the moderate interface strength. As.a result, the composite has better soft resis.ance and wear resis.ance than those of Cu and Cu alloy. With increase in super fine Al 2O 3, the density and electric conductivity of the composite decrease, but hardness.and strength increase.

关键词： hot pressing and sintering composites structure and properties mould

Long-Range Ordered Nanostructures of Assembling Macromolecules via Rational Design of Kinetic Pathways.a Computational Perspective

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Chinese Journal of Polymer science 2023年第9期41卷 1318-1328,I0004页

作者： liang-shun Zhang s.anghai Key Laboratory of Advanced Polymeric Materials School of Materials Science and EngineeringEast China University of Science and TechnologyShanghai200237China

Designing the kinetic pathways of assembling macromolecules such as block copolymers.and DNA strands is crucial not only for an achievement of thermodynamically equilibrium nanostructures over macroscopic areas,but also for a better unders.anding of formation process of higher-level superstructures where well-tailored assemblies.act as mesoscopic building *** analysis.and computer simulations provide excellent opportunities to microscopically reveal the kinetics.and mechanism of structural evolution as well as the collective behaviors of building *** this perspective,we summarize our efforts of theoretical and computational modelling to unders.and the long-range ordering mechanisms.and the organization kinetics of assembling macromolecules.along designable ***,we present the computational modelling and recent strategies of designable pathways for the achievement of long-range ***,from the computational views,we give the applications of pathway-designed strategies to explore the ordering mechanism and kinetics in the course of structural evolution,covering the block copolymers.and their nanocomposites under zone annealing as well as the hierarchical self-assembly of mesoscopic building units(e.g.,patchy micelles.and DNA-functionalized nanoparticles).Finally,we outlook future directions in the field of designable pathways for the achievement of long-range ordered *** perspective could promote further efforts towards the wide applications of theoretical and computational modelling in the construction of soft hybrid metamaterials.

关键词： Dynamic self-consistent field theory structural evolution Block copolymers Hierarchical self-assembly Polymerization

Impacts of degrading permafrost on streamflow in the source area of Yellow River on the Qinghai-Tibet Plateau,China

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Advances in Climate Change Res.arch 2019年第4期10卷 225-239页

作者： MA Qiang JIN Hui-Jun Victor F.BENsE LUO Dong-liang sergey s.MARCHENKO stuart A.HARRIs LAN Yong-Chao s.ate Key Laboratory of Frozen soils Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China College of Resources.and Environment University of Chinese Academy of SciencesBeijing100049China school of Civil Engineering Harbin Institute of TechnologyHarbin150090China Hydrology and Quantitative Water Management Group Department of Environmental SciencesWageningen UniversityWageningen6708PBthe Netherlands Geophysical Institute(GIPL) University of Alaska FairbanksFairbanks99775USA Department of Geography University of CalgaryCalgaryT3A 1E4Canada

Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(sAYR,above the Tanag hydrological s.ation)on the northeastern Qinghai-Tibet Plateau,West *** and to what extent does the degrading permafrost change the flow in the sAYR?According to s.asonal regimes of hydrological processes,the sAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River *** show that permafrost degradation may have released appreciable meltwater for recharging *** potential release rate of ground-ice melt-water in the sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological s.ation)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at ***/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts.are minor in other sub-basins in the *** hydraulic connectivity is expected to occur during and after certain degrees of permafrost *** impacts of permafrost degradation on the annual Yellow River streamflow in the sAYR at Tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at Tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice *** evapotranspiration,subs.antial weakening of the southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the sAYR.

关键词： streamflow Warming climate Permafrost degradation streamflow patterns source area of Yellow River(sAYR)

FeP nanorod array:A high-efficiency catalyst for electroreduction of NO to NH3 under ambient conditions

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Nano Res.arch 2022年第5期15卷 4008-4013页

作者： Jie liang Qiang Zhou Ting Mou Hongyu Chen Luchao Yue Yongsong Luo Qian Liu Mohamed s.Hamdy Abdulmohsen Ali Alshehri Feng Gong Xuping sun Institute of Fundamental and Frontier sciences University of Electronic Science and Technology of ChinaChengdu 610054China Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 211189China Institute for Advanced study Chengdu UniversityChengdu 610106China Catalysis Res.arch Group(CRG) Department of ChemistryCollege of ScienceKing Khalid UniversityP.O.Box 900461413 AbhaSaudi Arabia Chemistry Department Faculty of ScienceKing Abdulaziz UniversityP.O.Box 80203Jeddah 21589Saudi Arabia

sus.ainable mitigation of the continuously rising concentration of NO contaminants is.among the most urgent issues of this *** electrocatalytic conversion of NO into useful NH_(3)offers.an attractive path toward achieving sus.ainable NO abatement and NH_(3)production ***,its efficiency is challenged by the intense competition from hydrogen evolution reaction and relatively high energy barriers of NO *** is thus highly desirable to explore active electrocatalyst for NO reduction reaction and investigate the mechanisms on relevant ***,we introduce an FeP nanorod array on carbon cloth as.a high-efficiency catalyst for NO electroreduction to *** 0.2 M phosphate-buffered solution,this catalyst exhibits.a low onset potential of-0.014 ***,it achieves.a remarkable Faradaic efficiency of 88.49%and a large NH_(3)yield of 85.62μmol·h^(-1)cm^(-2),with durability for s.able NO conversion over 12 h of *** catalytic mechanism on FeP is investigated further by theoretical calculations.

关键词： FeP nanoarray NO reduction reaction NH_(3)synthesis electrocatalysis density functional theory