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TOUGHNESS INCREMENT BY CRACK GROWTH IN TOUGHENED STRUCTURAL MATERIALS

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Acta Mechanica Sinica 1991年第2期7卷 131-139页

作者： Yang Wei (Tsinghua University,Beijing 100084,china) 1. Tsinghua University 100084 Beijing China

Material toughening could be furnished by the energy dissipating wakes and bridging segments during crack *** to their contributions to the energy integral applicable to a growing crack,the toughening mechanisms are categorized as: dilatational plasticity and induced shear yielding in the crack wakes,bridging due to second inclusion phases,and the matrix bridging caused by wavy crack *** toughening analysis is pursued for structural polymers and composite materials reinforced by short aligned fibers.

关键词： material toughening crack growth bridging dilatational plasticity

Sm-Nd and Rb-Sr isotopic geochronology of the Xilin Gol Complex, Inner Mongolia

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Chinese Science Bulletin 1996年第13期41卷 1107-1110页

作者：徐备陈斌邵济安 Department of Geology Peking University Beijing 100871 China

1 Geologic setting The Xilin Gol Complex outcrops in the Bayan Gol area about 100 km to the northeast of Xilinhot City, Inner Mongolia (fig.1). Shao considered that the Xilin Gol Complex was an old tcrrane in the Pale... 详细信息

关键词： Sm-Nd and Rb-Sr isotopic geochronology Inner Mongolia.

DOMAIN AVERAGE SCM AND CONSTITUTIVE MODELLING OF POLYCRYSTALLINE AGGREGATES

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Science china Mathematics 1992年第10期35卷 1230-1241页

作者：仲政,杨卫,黄克智 Department of Mechanics Tsinghua University Beijing 100084 PRC Department of Engineering Mechanics Tongji University Shanghai 200092. PRC Department of Mechanics Tsinghua University Beijing 100084 PRC Department of Mechanics Tsinghua University Beijing 100084 PRC

A theoretical framework for the approximate constitutive assembly of polycrystals, termed henceforth domain average self consistent method, is developed to extend to SCM of Hill to adhered or sliding aggregates of arbitrary grain shape. The legitimacy and usefulness of the current theory are justified by the polycrystals composed of cubic grains and sliding spherical grains.

关键词： domain average SCM polycrystals elastic-plastic constitutive relations.

Providing Guaranteed Network Performance across Tenants:Advances,Challenges and Opportunities

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china Communications 2021年第2期18卷 152-174页

作者： Chengyuan Huang Jiao Zhang Tao Huang Yunjie Liu State Key Laboratory of Networking and Switching Technology BUPTBeijingChina Purple Mountain Laboratories NanjingChina

The varied network performance in the cloud hurts application *** increases the tenant’s cost and becomes the key hindrance to cloud *** is because virtual machines(VMs)belonging to one tenant can reside in multiple physical servers and communication interference across tenants occasionally occurs when encountering network *** order to prevent such unpredictability,it is critical for cloud providers to offer the guaranteed network performance at tenant *** a critical issue has drawn increasing attention in both academia and *** elaborate mechanisms are proposed to provide guaranteed network performance,such as guaranteed bandwidth or bounded message delay across ***,due to the intrinsic complexities and limited capabilities of commodity hardware,the deployment of these mechanisms still faces great challenges in current cloud ***,with the rapid development of new technologies,there are new opportunities to improve the performance of existing works,but these possibilities are not under full discussion ***,in this paper,we survey the latest development of the network performance guarantee approaches and summarize them based on their ***,we explore and discuss the possibilities of using emerging technologies as knobs to upgrade the performance or overcome the inherent shortcomings of existing *** hope this article will help readers quickly Received:Apr.07,2020 Revised:Oct.23,2020 Editor:Haifeng Zheng understand the causes of the problems and serve as a guide to motivate researchers to develop innovative algorithms and frameworks.

关键词： cloud computing network performance guaranteed bandwidth guaranteed delay

Temperature dependency of VOCs release characteristics of asphalt materials under varying test conditions

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第2期9卷 280-292页

作者： Xiwen Chang Yue Xiao Yongshuang Long Feng Wang Zhanping You State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China Hubei Provincial Academy of Building Research and Design Co. LtdWuhan 430071China Department of Civil and Environmental Engineering Michigan Technological UniversityHoughtonMI 49931USA

Asphalt pavement is increasingly used in paving and ***,the release of volatile organic compounds(VOCs)from asphalt harm both the environment and *** methods were applied to characterize the VOCs for better understanding and ***,asphalt VOCs have huge heating temperature dependency,which makes the asphalt VOCs’characterization *** this research,three kinds of heating conditions,thermal gravimetric(TG)analyzer,pyrolysis(PY)analyzer,and thermal desorber(TD),were compared to determine the temperature dependency of VOC release *** chromatography and mass spectrometer(GC-MS)were then coupled for VOC *** indicated that the TG heating condition can surely simulate the volatilization of VOCs from some asphalt that is not in contact with air(no oxygen)during the actual construction process,while PY and TD represent the substances released by the asphalt due to the boiling point at a certain temperature and under the actual construction process,*** components detected by TG heating condition are both large and small molecules,while PY and TD heating condition will detect large molecules or small molecules,*** VOC composition results under various heating conditions reflect the chemical reaction law of asphalt molecules in the heating *** heating asphalt binders to a higher temperature,macromolecular substances will gradually crack and oxidize into small molecular substances,sulfides and *** the increase of temperature,the change trend of VOC components under different conditions is different.

关键词： Asphalt materials Volatile organic compounds Thermal gravimetric analysis-mass spectrometer Pyrolysis-gas chromatography-mass spectrometer Thermal desorption-gas chromatography-mass spectrometer

Improvements on Mean Free Wave Surface Modeling

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china Ocean Engineering 2002年第4期17卷 549-560页

作者：董国海滕斌程亮 The State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China Department of Civil Engineering The University of Western AustraliaNedlandsWestern Australia 6907Australia

Some new results of the modeling of mean free surface of waves or wave set-up are presented. The stream function wave theory is applied to incident short waves. The limiting wave steepness is adopted as the wave breaker index in the calculation of wave breaking dissipation. The model is based on Roelvink (1993), but the numerical techniques used in the solution are based on the Weighted-Average Flux (WAF) method (Watson et al., 1992), with Time-Operator-Splitting (TOS) used for the treatment of the source terms. This method allows a small number of computational points to be used, and is particularly efficient in modeling wave set-up. The short wave (or incident primary wave) energy equation is solved by use of a traditional Lax-Wendroff technique. The present model is found to be satisfactory compared with the measurements conducted by Stive (1983).

关键词： mean free surface radiation stress wave breaker index limiting wave steepness stream function wave theory

High undercooling of bulk water during acoustic levitation

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Science china(Physics,Mechanics & Astronomy) 2003年第3期46卷 259-267页

作者：吕勇军曹崇德魏炳波 Department of Applied Physics Northwestern Polytechnical UniversityXi'an 710072China

The experiments on undercooling of acoustically levitated water drops with the radius of 5-8 mm are carried out, and the maximum undercooling of 24 K is obtained in such a containerless state. Various factors influencing the undercoolability of water under acoustic levitation are synthetically analyzed. The experimental results indicate that impurities tend to decrease the undercooling level, whereas the dominant factor is the effect of ultrasound. The stirring and cavitation effects of ultrasound tend to stimulate the nucleation of water and prevent further bulk undercooling in experiments. The stirring effect provides some extra energy fluctuation to overcome the thermodynamic barrier for nucleation. The local high pressure caused by cavitation effect increases the local undercooling in water and stimulates nucleation before the achievement of a large bulk undercooling. According to the cooling curves, the dendrite growth velocity of ice is estimated, which is in good agreement with the theoretical prediction at the lower undercooling. The theoretical calculation predicts a dendrite growth velocity of 0.23 m/s corresponding to the maximum undercooling of 24 K, at which the rapid solidification of ice occurs.

关键词： acoustic levitation, undercooling, water, crystal growth.

Influence of Random Potentials on the Current of the Molecular Motor Model

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Chinese Physics Letters 2001年第11期18卷 1431-1434页

作者： JIA Ya LI Jia-rong Department of Physics Huazhong Normal UniversityWuhan 430079 Institute of Particle Physics:Huazhong Normal University Wuhan 430079

The current of the molecular motor model disturbed by random potentials, which involve the dichotomous and Ornstein-Uhlenbeck potentials, is studied using a finite-space correlation function. It is found that: (i) the amplitude and the correlation length of random potentials play opposing roles in the transport of the molecular motor model;(ii) a random potential with small amplitude and large correlation length is very useful in the molecular motor system.

关键词： function. disturbed Molecular

Nonlinear analysis of combustion oscillations in a cavity-based supersonic combustor

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Science china(Technological Sciences) 2013年第5期56卷 1093-1101页

作者： WANG HongBo WANG ZhenGuo SUN MingBo WU HaiYan Science and Technology on Scramjet Laboratory National University of Defense Technology

Combustion oscillations in a supersonic combustor with hydrogen injection upstream of a cavity flameholder are investigated using nonlinear analysis based on experimental *** series of both flamefront and wall pressure are acquired,and the state space reconstruction approach is adopted to characterize the nonlinear behavior of the combustion *** overall equivalence ratios,0.038,0.076 and 0.11,are *** existence of a chaotic source in the present combustion system is *** correlation dimension and the largest Lyapunov exponent tend to become larger with the increasing equivalence ratio,indicating a more complicated and unstable combustion *** particular,it is found that the correlation dimension for the highest equivalence ratio is much greater than those of the two lower equivalence *** possible reasons responsible for the observed nonlinear behaviors are *** is the shock-related instabilities and the other is the transition of combustion stabilization mode between the cavity and jet-wake stabilized mode.

关键词： cavity supersonic combustion oscillation nonlinear