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Effects of air relief openings on the mitigation of solitary wave forces on bridge decks

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Journal of Hydrodynamics 2019年第3期31卷 594-602页

作者： Sheng-chao Xiao An-xin Guo Ministry-of-Education Key Laboratory of Structural Dynamic Behavior and Control School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Department of Civil Engineering The University of Queensland Brisbane 4072 Australia

For inverted T-type bridge decks, the air entrapped in the chambers between adjacent girders could increase the wave forces and lead to the destruction of the bridge decks. This paper studies the effects of the air relief openings (ARO) on the mitigation of the solitary wave-induced forces on the bridge decks. Hydrodynamic experiments are conducted for three inverted T-type decks with four, five, and six girders with different wave properties and deck clearances. The open source computational fluid dynamics toolbox OpenFOAM is adopted to conduct numerical simulations for the effects of the AROs. Since the numerical results correlate well with the measurements, the mechanism of the wave-structure interaction can be revealed by the numerical flow fields. Furthermore, the relationship between the shape and the volume of the ARO and the wave forces on the bridge decks, as well as the contribution of each ARO to the effect of the wave force mitigation, is also obtained from the numerical results of the OpenFOAM. Experimental and numerical results demonstrate that the AROs could effectively reduce the vertical wave forces on the bridge decks. The effects of the AROs increase with the increase of the volume of the ARO, while the shape of the ARO has no effect on the reduction of the wave forces.

关键词： Air entrapped hydrodynamic experiment solitary wave forces bridge decks OpenFOAM

Detecting van der Waals forces between a single polymer repeating unit and a solid surface in high vacuum

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Nano Research 2019年第1期12卷 57-61页

作者： Wanhao Cai Chen Xiao Linmao Qian Shuxun Cui Key Laboratory of Advanced Technologies of Materials(Ministry of Education) Southwest Jiaotong UniversityChengdu 610031China

Ubiquitous van der Waals(vdW)forces are very importa nt for nano *** the vdW forces between two surfaces(or two layers)have been measured for several decades,a direct detection at the single-molecule level is still ***,we report a novel method to solve this problem in high vacuum by means of AFM-based sin gle-molecule force spectroscopy(SMFS).Solve nt molecules and surface adsorbed water are removed thoroughly under high vacuum so that the situation is greatly simplified.A constant force plateau can be observed when a polymer chain is peeled off from a substrate in high ***,the vdW forces between one polymer repeating unit and the substrates can be *** experimental results show that the vdW forces(typical range:21-54 pN)are dependent on the species of substrates and the size of polymer repeating unit,which is in good accordance with the theoretical *** is expected that this novel method can be applied to detect other non-covalent interactions(such as hydrogen bond andπ-πstacking)at the single-molecule level in the future.

关键词： van der Waals forces high vacuum atomic force microscopy single-molecule studies polymer desorption

ForSA — A New Software Defined Network Architecture Based on forces

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China Communications 2016年第S1期13卷 16-31页

作者： LI Chuanhuang CEN Lijie GONG Liang WANG Weiming JIN Rong LAN Julong School of Information and Electronic Engineering Zhejiang Gongshang University National Digital Switching System Engineering & Technological R&D Center

In recent years, SDN(Software Defined Network) as a new network architecture has become the hot research point. Meanwhile,the well-known Open Flow-based SDN got a lot of attention. But it can't provide a flexible and effective network resource description *** an open programmable technology, For CES(Forwarding and Control Element Separation)has also been concerned. However, For CES is confined within a single network node and cannot be applied to the entire network. This paper proposes a new architecture — ForS A(ForC ESbased SDN architecture). The architecture is added a configuration layer based on the traditional SDN architecture, which solves the problem that the northbound interface is not clear between the application layer and the control layer in the SDN architecture. ForS A also implements the compatibility within various forwarding devices in the forwarding layer.

关键词： software defined network forces SDN architecture

Efficient training of ANN potentials by including atomic forces via Taylor expansion and application to water and a transition-metal oxide

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npj Computational Materials 2020年第1期6卷 1205-1218页

作者： April M.Cooper Johannes Kästner Alexander Urban Nongnuch Artrith School of Chemistry University of St AndrewsSt AndrewsUK Institute for Theoretical Chemistry University of StuttgartStuttgartGermany Department of Chemical Engineering Columbia UniversityNew YorkNYUSA

Artificial neural network(ANN)potentials enable the efficient large-scale atomistic modeling of complex materials with near firstprinciples *** molecular dynamics simulations,accurate energies and interatomic forces are a prerequisite,but training ANN potentials simultaneously on energies and forces from electronic structure calculations is computationally ***,we introduce an efficient alternative method for the training of ANN potentials on energy and force information,based on an extrapolation of the total energy via a Taylor *** translating the force information to approximate energies,the quadratic scaling with the number of atoms exhibited by conventional force-training methods can be avoided,which enables the training on reference datasets containing complex atomic structures.

关键词： forces enable atomic

WAVE-CURRENT forces ON BIPILES IN TANDEM ARRAY

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Journal of Hydrodynamics 1991年第4期3卷 66-75页

作者： Yu-cheng, Li Feng-long, Wang Dalian Univ of Technology Dalian China

The in-line and lift forces on bipiles in tandem array induced by both irregular waves and currents were investigated experimentally in this paper. The characteristics in both time and frequency domain of inline, lift and resultant forces as well were analyzed. The grouping effect coefficients of in-line and resultant forces on two piles related to KC number and relative spacing parameters are given. A comparison of the magnitude and direction of resultant forces on bipiles in tandem array with the corresponding values for single cylinder is also made.

关键词： Hydrodynamics Fluid Structure Interaction Mathematical Techniques Frequency Domain Analysis Mathematical Techniques Time Domain Analysis Mechanical Variables Measurement forces Water Waves Analysis

Elastoplastic analysis for infinite plate with centric crack loaded by two pairs of point shear forces

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Journal of Central South University of Technology 2005年第Z1期12卷 189-193页

作者： ZHOU Xiao-ping LING Tong-hua School of Civil Engineering Chongqing University Chongqing 400045 China School of Geoscience and Environmental Engineering Central South University Changsha 410083 China

The near crack line analysis method was used to investigate a crack loaded by two pairs of point shear forces in an infinite plate in an elastic-perfectly plastic solid, and the analytical solution was obtained. The solutions include: the unit normal vector of the elastic-plastic boundary near the crack line, the elastic-plastic stress fields near crack line, law that the length of the plastic zone along the crack line is varied with an external loads, and the bearing capacity of an infinite plate with a center crack loaded by two pairs of point shear forces. The results are sufficiently precise near the crack line because the assumptions of the small scale yielding theory have not been made and no other assumption have been taken.

关键词： near crack line analysis method elastoplastie analytical solution two pairs of point shear forces

Abnormal ground reaction forces lead to a general decline in gait speed in knee osteoarthritis patients

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世界骨科杂志：英文版 2017年第4期8卷 322-328页

作者： Anatole Vilhelm Wiik Adeel Aqil Mads Brevadt Gareth Jones Justin Cobb MSk Lab Department of Surgery and CancerCharing Cross Hospital Imperial College London South Kensington Campus

AIM To analyse ground reaction forces at higher speeds using another method to be more sensitive in assessing significant gait abnormalities. METHODS A total of 44 subjects, consisting of 24 knee osteoarthritis(OA) patients and 20 healthy controls were analysed. The knee OA patients were recruited from an orthopaedic clinic that were awaiting knee replacement. All subjects had their gait patterns during stance phase at top walking speed assessed on a validated treadmill instrumented with tandem force plates. Temporal measurements and ground reaction forces(GRFs) along with a novel impulse technique were collected for both limbs and a symmetry ratio was applied to all variables to assess inter-limb asymmetry. All continuous variables for each group were compared using a student t-test and χ2 analysis for categorical variables with significance set at α = 0.05. Receiver operator characteristics curves were utilised to determine best discriminating *** The knee OA patients were older(66 ± 7 years vs 53 ± 9 years, P = 0.01) and heavier(body mass index: 31 ± 6 vs 23 ± 7, P forces and impulse were significantly(P < 0.0001) worse(18% and 12% respectively) for the knee OA patients when compared to the controls. Receiver operating characteristic curves analysis demonstrated total impulse to be the best discriminator of asymmetry, with an area under the curve of 0.902, with a cut-off of-3% and a specificity of 95% and sensitivity of 88%.CONCLUSION Abnormal GRFs in knee osteoarthritis are clearly evident a

关键词： Gait Treadmill Ground reaction forces Symmetry Osteoarthritis Knee

The spatio-temporal distribution of thermodynamic forces at the land-atmosphere interface in China

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Science China Earth Sciences 2010年第11期53卷 42-53页

作者： LEVY Jason K. L. Douglas Wilder School of Government and Public Affairs Virginia Commonwealth University

Correlation analysis and the complementary relationship model are used to indirectly measure and characterize the dynamic and thermodynamic properties at the land-atmosphere interface in *** show that thermodynamic forces driving the exchange fluxes of energy,water and carbon between the land surface and the overlying atmosphere are significantly enhanced along the mid-upper reaches of the Yangtze River basin around Sichuan Basin and the northern region of *** thermodynamic forces exhibit a decreasing trend in southern Xinjiang and some regions of *** cloud cover was shown to be a significant factor leading to changes in thermodynamic properties at the land-atmosphere *** Pacific Subtropical High (WPSH) and storm data provide strong evidence that a changing synoptic system is likely a principle factor causing the abnormal spatiotemporal distribution of thermodynamic forces over the land surface in *** data also suggests that cyclical and quasi-cyclical fluctuations of low cloud cover in most regions of China are responsible for annual rainfall *** the same time,NOAA-AVHRR satellite remote sensing data illustrates that changes to land surface characteristics may cause atypical spatiotemporal distributions of thermodynamic forces over the land *** show that thermodynamic forces are weakening in regions with increasing ***,where urbanization has decreased the quantity of vegetation,thermodynamic forces are ***,an increase in large-scale thermodynamic forces is associated with a reduction in low cloud cover due to changes in the synoptic system.

关键词： thermodynamic forces Western Pacific Subtropical High low cloud cover remotely sensed data

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Single-axis ultrasound levitation system with annular clamping forces

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Chinese Journal of Acoustics 2019年第2期38卷 189-200页

作者： YIN Guanjun LI Pan FAN Haoran GUO Jianzhong Institute of Applied Acoustics School of Physics and Information TechnologyShaanxi Normal University

Based on the principle of acoustic levitation,a single-axis ultrasonic levitation system(SAULS) with convex sides was designed.A normal SAULS only provides a levitation force(LF) against the gravity of the ***,such systems also provide an annular clamping force(ACF) surrounding the levitated samples,and improve levitation stability of samples in the standing wave *** the finite-difference time-domain method,we investigated the force distributions in different resonance cavities and the factors that influence the magnitude of the levitation force in optimizing the SAULS and the *** theoretical analyses and experimental results indicate that the stability of levitation in this special SAULS is improved with the ACF from its designed convex-side *** can be developed into a simple device in levitating and moving samples steadily in related experiments and applications.

关键词： ACF Single-axis ultrasound levitation system with annular clamping forces