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| 1 | Probabilistic stability analyses of undrained slopes by 3D random fields and finite element methods显示文摘A long slope consisting of spatially random soils is a common geographical feature. This paper examined the necessity of three-dimensional(3 D) analysis when dealing with slope with full randomness in soil properties. Although 3 D random finite element analysis can well reflect the spatial variability of soil properties, it is often time-consuming for probabilistic stability analysis. For this reason, we also examined the least advantageous(or most pessimistic) cross-section of the studied slope. The concept of'most pessimistic' refers to the minimal cross-sectional average of undrained shear strength. The selection of the most pessimistic section is achievable by simulating the undrained shear strength as a 3 D random field. Random finite element analysis results suggest that two-dimensional(2 D) plane strain analysis based the most pessimistic cross-section generally provides a more conservative result than the corresponding full 3 D analysis. The level of conservativeness is around 15% on average. This result may have engineering implications for slope design where computationally tractable 2 D analyses based on the procedure proposed in this study could ensure conservative results. | Yong Liu Wengang Zhang Lei Zhang Zhiren Zhu Jun Hu Hong Wei | 2018 | Geoscience Frontiers2018，9，6： | 17 |
| 2 | Modeling screening efficiency with vibrational parameters based on DEM 3D simulation显示文摘The efficiency of particle screening was studied over a range of vibrational parameters including amplitude, frequency and vibrational direction. The Discrete Element Method (DEM) was used to simulate the screening process. A functional relationship between efficiency and the parameters, both singly and combined, is established. The function is a complicated exponential. Optimal amplitude and frequency values are smaller for particles near the mesh and larger for other particles. The optimum vibration angle is 45° for nearly all kinds of particles. A transverse velocity, V⊥, was defined and V⊥=0.2 m/s was identified to be the most efficient operating point by both simulation and experimental observation. Comparison of these results with those reported by others is included. | CHEN Yanhua TONG Xin | 2010 | Mining Science and Technology2010，20，4： | 12 |
| 3 | A combined application of micro-vortex generator and boundary layer suction in a high-load compressor cascade显示文摘In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex generator with a special configuration and the longitudinal suction slot are adopted. The calculated results show that a reverse flow region, which is considered the main reason for occurring stall at 7.9° incidence, grows and collapses rapidly near the leading edge and leads to two critical points occurring on the end-wall with the increasing incidence in the baseline. As the micro-vortex generator is introduced in the baseline cascade, the corner separation is switched to a trailing edge separation by the thrust from the induced vortex. Meanwhile, the occurrence of failure is delayed due to the mixed low energy fluid and main flow. The synergistic effects between the micro-vortex generator and the boundary layer suction on the performance of the cascade are superior to the baseline at all the incidence conditions before the occurrence of failure, and the sudden deterioration of the cascade occurs at 10.3° incidence. The optimal results show that the farther upstream suction position, the lower total pressure loss of the cascade with vortex generator at the near stall condition. Moreover, the induced vortex with a leg can migrate the accumulated low energy fluid backward to delay the occurrence of stall. | Shan MA Wuli CHU Haoguang ZHANG Xiangjun LI Haiyang KUANG | 2019 | Chinese Journal of Aeronautics2019，32，5： | 9 |
| 4 | Contrasting responses of net primary productivity to inter-annual variability and changes of climate among three forest types in northern China显示文摘Aims A lack of explicit information on differential controls on net primary productivity(NPP)across regions and ecosystem types is largely responsible for uncertainties in global trajectories of terrestrial carbon balance with changing environment.The objectives of this study were to determine how NPP of different forest types would respond to inter-annual variability of climate and to examine the responses of NPP to future climate change scenarios across contrasting forest types in northern China.Methods We investigated inter-annual variations of NPP in relation to climate variability across three forest types in northern China,including a boreal forest dominated by Larix gmelinii Rupr.,and two temperate forests dominated by Pinus tabulaeformis Carr.and Quercus wutaishanica Mayr.,respectively,and studied the responses of NPP in these forests to predicted changes in climate for the periods 2011–40,2041–70 and 2070–100 under carbon emission scenarios A2 and B2 of Intergovernmental Panel on Climate Change.We simulated the responses of NPP to predicted changes in future climate as well as inter-annual variability of the present climate with the Biome-BGC version 4.2 based on site-and species-specific parameters.The modeled forest NPP data were validated against values in literature for similar types of forests and compared with inter-annual growth variations reflected by tree-ring width index(RWI)at the study sites.Important Findings Inter-annual variations in modeled NPP during the period 1960–06 were mostly consistent with the temporal patterns in RWI.There were contrasting responses of modeled NPP among the three forest types to inter-annual variability of the present climate as well as to predicted changes in future climate.The modeled NPP was positively related to annual mean air temperature in the L.gmelinii forest(P<0.001),but negatively in the P.tabulaeformis forest(P=0.05)and the Q.wutaishanica forest(P=0.03),while the relationships of modeled NPP with annual precipitation for the three forest types were all positive.Multiple stepwise regression analyses showed that temperature was a more important constraint of NPP than precipitation in the L.gmelinii forest,whereas precipitation appeared to be a prominent factor limiting the growth in P.tabulaeformis and Q.wutaishanica.Model simulations suggest marked,but differential increases in NPP across the three forest types with predicted changes in future climate. | Shuai Ouyang Xiangping Wang Yulian Wu Osbert Jianxin Sun | 2014 | Journal of Plant Ecology2014，7，3： | 9 |
| 5 | Drawdown mechanism of light particles in baffled stirred tank for the KR desulphurization process显示文摘To improve the efficiency of the desulfurization process, the drawdown mechanism of light particles in stirred tank is studied in this paper. For both up and down pumping modes, the just drawdown speeds(Njd) of floating particles in transformative Kanbara Reactor(KR) are measured in one and four baffled stirred tanks experimentally. Then numerical simulations with standard k-ε model coupled with volume of fluid model(VOF) and discrete phase model(DPM) are conducted to analyze the flow field at the just drawdown speed Njd. The torques on the impeller obtained from experiments and simulations agree well with each other, which indicates the validity of our numerical simulations. Based on the simulations, three main drawdown mechanisms for floating particles, the axial circulation, turbulent fluctuation and largescale eddies, are analyzed. It's found that the axial circulation dominates the drawdown process at small submergence(S = 1/4 T and 1/3 T) and the large-scale eddies play a major role at large submergence(S = 2/3 T and 3/4 T). Besides, the turbulent fluctuation affects the drawdown process significantly for up pumping mode at small submergence(S = 1/4 T and 1/3 T) and for down pumping mode at large submergence(S = 2/3 T and 3/4 T). This paper helps to provide a more comprehensive understanding of the KR desulphurizer drawdown process in the baffled stirred tank. | Meng Li Yangbo Tan Jianglong Sun De Xie Zeng Liu | 2019 | Chinese Journal of Chemical Engineering2019，27，2： | 8 |
| 6 | Developments of numerical methods for linear and nonlinear fluid-solid interaction dynamics with applications显示文摘 | Jing Tang XING | 2016 | 力学进展2016，46，1： | 8 |
| 7 | Rock-soil slope stability analysis by two-phase random media and finite elements显示文摘To investigate the strong random nature of the geometric interfaces between soil and rock, a rock-soil slope is considered as a two-phase random medium. A nonlinear translation of a Gaussian field is utilized to simulate the two-phase random media, such that the soil(or rock) volume fraction and the inclination of the soil layer can be examined. The finite element method with random media incorporated as the material properties is used to determine the factor of safety of the rock-soil slope. Monte-Carlo simulations are used to estimate the statistical characteristics of the factor of safety. The failure mode of the rock-soil slope is examined by observing the maximum principal plastic strain at incipient slope failure. It is found that the critical surface of a rock-soil slope is fairly irregular, and it significantly differs from that of a pure soil slope. The factor of safety is sensitive to the soil volume faction, but it is predictable. The average factor of safety could be well predicted by the weighted harmonic average between the strength of soil and rock; the prediction model is practical and simple. Parametric studies on the inclination of the soil layer demonstrate that the most instable scenario occurs when the slope angle is consistent with the inclination of the soil layer. | Yong Liu Huawen Xiao Kai Yao Jun Hu Hong Wei | 2018 | Geoscience Frontiers2018，9，6： | 7 |
| 8 | Theoretical study of 2-mercaptobenzimidazole derivatives as chelating collectors in flotation separation of galena and pyrite显示文摘Three 2-mercaptobenzimidazole derivatives,1-ethyl-2-mercapto-benzimidazole(EMBI),1-propyl-2-mercapto-benzimidazole(PMBI)and 1-benze-2-mercapto-benzimidazole(BMBI),were designed and synthesized in the paper,and their collecting behavior in flotation separation process of galena over pyrite was investigated by flotation tests on lab scale.Apart from this,density functional theory(DFT)calculation and molecular dynamics(MD)simulation were also used to elucidate their collecting mechanism.Results of flotation tests indicate that separation of galena over pyrite is feasible at pH 10,and BMBI has the best floatability among three collectors.DFT calculations show that BMBI has the highest occupied molecular orbital(HOMO)energy and strongest collecting effciency.The adsorption mode of three collectors on mineral surface by MD method indicates that the combination processes of collectors with mineral are exothermic,and the higher the binding energy,the frmer the collector adsorbs on the mineral surface and the higher collecting capacity.The calculation results demonstrate that the floatability of three collectors follows the order:BMBI>PMBI>EMBI,which is highly consistent with the flotation tests. | Qin Wei Xu Shengming Xie Qiang | 2013 | International Journal of Mining Science and Technology2013，23，4： | 7 |
| 9 | Stability analysis of backflling in subsiding area and optimization of the stoping sequence显示文摘In underground mining by sublevel caving method, the deformation and damage of the surface induced by subsidence are the major challenging issues. The dynamic and soft backflling body increases the safety risks in the subsiding area. In this paper, taking Zhangfushan iron mine as an example, the ore body and the general layout are focused on the safety of backflling of mined-out area. Then, we use the ANSYS software to construct a three-dimensional(3D) model for the mining area in the Zhangfushan iron mine. According to the simulation results of the initial mining stages, the ore body is stoped step by step as suggested in the design. The stability of the backflling is back analyzed based on the monitored displacements, considering the stress distribution to optimize the stoping sequence. The simulations show that a reasonable stoping sequence can minimize the concentration of high compressive stress and ensure the safety of stoping of the ore body. | Ping Wang Huiqiang Li Yan Li Bo Cheng | 2013 | Journal of Rock Mechanics and Geotechnical Engineering2013，5，6： | 6 |
| 10 | Discrete modeling of rock joints with a smooth-joint contact model显示文摘Structural defects such as joints or faults are inherent to almost any rock mass.In many situations those defects have a major impact on slope stability as they can control the possible failure mechanisms.Having a good estimate of their strength then becomes crucial.The roughness of a structure is a major contributor to its strength through two different aspects,i.e.the morphology of the surface(or the shape)and the strength of the asperities(related to the strength of the rock).In the current state of practice,roughness is assessed through idealized descriptions(Patton strength criterion)or through empirical parameters(Barton JRC).In both cases,the multi-dimensionality of the roughness is ignored.In this study,we propose to take advantage of the latest developments in numerical techniques.With3D photogrammetry and/or laser mapping,practitioners have access to the real morphology of an exposed structure.The derived triangulated surface was introduced into the DEM(discrete element method)code PFC3D to create a synthetic rock joint.The interaction between particles on either side of the discontinuity was described by a smooth-joint model(SJM),hence suppressing the artificial roughness introduced by the particle discretization.Shear tests were then performed on the synthetic rock joint.A good correspondence between strengths predicted by the model and strengths derived from well-established techniques was obtained for thefirst time.Amongst the benefits of the methodology is the possibility offered by the model to be used in a quantitative way for shear strength estimates,to reproduce the progressive degradation of the asperities upon shearing and to analyze structures of different scales without introducing any empirical relation. | C.Lambert C.Coll | 2014 | Journal of Rock Mechanics and Geotechnical Engineering2014，6，1： | 5 |
| 11 | Research on the Glass Transition Temperature and Mechanical Properties of Poly(vinyl chloride)/Dioctyl Phthalate (PVC/DOP) Blends by Molecular Dynamics Simulations显示文摘To effectively improve the performance and expand the applications of polymers, molecular dynamics(MD) simulations with the COMPASS force field have been applied to predict the miscibility, glass transition temperature(Tg), and mechanical properties of poly(vinyl chloride)/dioctyl phthalate(PVC/DOP) blends. The solubility parameter values obtained are in good agreement with the reference data and the little difference(|Δδ|< 2.0 MPa0.5) between two components indicates that PVC/DOP is a miscible system. Tg is predicted by the slope of the free volume and density versus temperature simulation data based on density and free volume theory which is agree well with the experimental data. In addition, the analyses of mechanical properties results indicate that the values of Young’s modulus(E), bulk modulus(K), and shear modulus(G) decrease with the addition of DOP, demonstrating that the rigidity of material is weakened and the ductility is improved. The mechanical properties can also be effectively improved by increasing the temperature, which may provide a more flexible mixture, with lower E, K, G but an increased ductility. | Jing Li Shao-Hua Jin Guan-Chao Lan Zi-Shuai Xu Lu-Ting Wang Na Wang Li-Jie Li | 2019 | Chinese Journal of Polymer Science2019，37，8： | 4 |
| 12 | Low temperature annealing of metals with electrical wind force effects显示文摘Conventional annealing is a slow, high temperature process that involves heating atoms uniformly, i.e., in both defective and crystalline regions. This study explores an electrical alternative for energy efficiency,where moderate current density is used to generate electron wind force that produces the same outcome as the thermal annealing process. We demonstrate this on a zirconium alloy using in-situ electron back scattered diffraction(EBSD) inside a scanning electron microscope(SEM) and juxtaposing the results with that from thermal annealing. Contrary to common belief that resistive heating is the dominant factor, we show that 5 × 10~4 A/cm^2 current density can anneal the material in less than 15 min at only135?C. The resulting microstructure is essentially the same as that obtained with 600?C processing for360 min. We propose that unlike temperature, the electron wind force specifically targets the defective regions, which leads to unprecedented time and energy efficiency. This hypothesis was investigated with molecular dynamics simulation that implements mechanical equivalent of electron wind force to provide the atomistic insights on defect annihilation and grain growth. | Daudi Waryoba Zahabul Islam Baoming Wang Aman Haque | 2019 | Journal of Materials Science & Technology2019，35，4： | 4 |
| 13 | Application of wavelet transform in structural health monitoring显示文摘Structural health monitoring(SHM)is a process of implementing a damage detection strategy in existing structures to evaluate their condition to ensure safety.The changes in the material,geometric and/or structural properties affect structural responses,which can be captured and analyzed for condition assessment.Various vibration-based damage detection algorithms have been developed in the past few decades.Among them,wavelet transform(WT)gained popularity as an efficient method of signal processing to build a framework to identify modal properties and detect damage in structures.This article presents the state-of-the-art implementation of various WT tools in SHM with a focus on civil structures.The unique features and limitations of WT,and a comparison of WT and other signal processing methods,are further discussed.The comprehensive literature review in this study will help interested researchers to investigate the use of WT in SHM to meet their specific needs. | Yashodhya Kankanamge Yufeng Hu Xiaoyun Shao | 2020 | Earthquake Engineering and Engineering Vibration2020，19，2： | 4 |
| 14 | A NOVEL SLIGHTLY COMPRESSIBLE MODEL FOR LOW MACH NUMBER PERFECT GAS FLOW CALCULATION显示文摘By analyzing the characteristics of low Mach number perfect gasflows, a novel Slightly Compressible Model (SCM) for low Mach number perfect gasflows is derived. In view of numerical calculations, this model is proved very efficient,for it is kept within the p-v frame but does not have to satisfy the time consumingdivergence-free condition in order to get the incompressible Navier-Stokes equationsolutions. Writing the equations in the form of conservation laws, we have derivedthe characteristic systems which are necessary for numerical calculations. A cell-centered finite-volume method with flux difference upwind-biased schemes is used forthe equation solutions and a new Exact Newton Relaxation (ENR) implicit methodis developed. Various computed results are presented to validate the present model.Laminar flow solutions over a circular cylinder with wake developing and vortex shed-ding are presented. Results for inviscid flow over a sphere are compared in excellentagreement with the exact analytic incompressible solution. Three-dimensional viscousflow solutions over sphere and prolate spheroid are also calculated and compared wellwith experiments and other incompressible solutions. Finally, good convergent per-formaces are shown for sphere viscous flows. | 邓小刚 庄逢甘 | 2002 | Acta Mechanica Sinica2002，18，3： | 4 |
| 15 | Preliminary investigation on electrothermal instabilities in early phases of cylindrical foil implosions on primary test stand facility显示文摘Recent experiments on the implosions of 15-mm long and 2-μm thick aluminum liners having a diameter of 12.8 mm have been performed on the primary test stand(PTS) facility. The stratified structures are observed as alternating dark and light transverse stripes in the laser shadowgraph images. These striations perpendicular to the current flow are formed early in the implosion, i.e., at the stage when the bulk of the material mass was almost at rest. A two-dimensional(2 D)magnetohydrodynamics(MHD) code is employed to simulate the behavior of liner dynamics in the early phases. It is found that the striations may be produced by the electrothermal instability(ETI) that results from non-uniform Joule heating due to the characteristic relation between the resistivity and the temperature. In 2 D simulations, the stratified structures can be seen obviously in both density and temperature contours as the liner expands rapidly. By analyzing instability spectrum, the dominant wavelengths of the perturbations are 8.33 μm–20.0 μm, which agree qualitatively with the theoretical predictions.It is also interesting to show that ETI provides a significant seed to the subsequent magneto Rayleigh–Taylor(MRT)instability. | 王冠琼 肖德龙 但家坤 张扬 丁宁 黄显宾 王小光 孙顺凯 薛创 束小建 | 2019 | Chinese Physics B2019，28，2： | 4 |
| 16 | A new cellular automaton model accounting for stochasticity in traffic flow induced by heterogeneity in driving behavior显示文摘A new reliable cellular automaon(CA) model designed to account for stochasticity in traffic flow induced by heterogeneity in driving behavior is presented.The proposed model differs from most existing CA models in that this new model focuses on describing traffic phenomena by coding into its rules the key idea that a vehicle's moving state is directly determined by a driver stepping on the accelerator or on the brake(the vehicle's acceleration).Acceleration obeys a deformed continuous distribution function when considering the heterogeneity in driving behavior and the safe distance, rather than equaling a fixed acceleration value with a probability, as is the rule in many existing CA models.Simulation results show that the new proposed model is capable of reproducing empirical findings in real traffic system.Moreover, this new model makes it possible to implement in-depth analysis of correlations between a vehicle's state parameters. | 倪晓勇 黄弘 | 2019 | Chinese Physics B2019，28，9： | 3 |
| 17 | The Uncertainty of Mesoscale Numerical Prediction of Heavy Rain in South China and the Ensemble Simulations显示文摘In the context of non-hydrostatic MM5 version we have explored the impact of convective parameteri- zation schemes on uncertainty in mesoscale numerical prediction of South China heavy rain and mesoscale heavy rainfall short-range ensemble simulation by using two kinds of physics perturbation methods through a heavy rain case occurring on June 8, 1998 in Guangdong and Fujian Provinces. The results show the physical process of impacts of convective schemes on heavy rainfall is that different latent heat of convective condensation produced by different convective schemes can make local temperature perturbation, leading to the difference of local vertical speed by the intrinsic dynamic and thermodynamic processes of atmosphere, and therefore, making difference of the timing, locations and strength of mesh scale and subgrid scale pre- cipitation later. New precipitations become the new source of latent heat and temperature perturbation, which finally make the dynamic and thermodynamic structures different in the simulations. Two kinds of methods are used to construct different model version stochastically. The first one is using different convec- tive parameterization and planetary boundary layer schemes, the second is adjusting different parameters of convective trigger functions in Grell scheme. The results indicate that the first ensemble simulations can provide more uncertainty information of location and strength of heavy rainfall than the second. The single determinate predictions of heavy rain are unstable; physics ensemble predictions can reflect the uncertainty of heavy rain, provide more useful guidance and have higher application value. Physics ensembles suggest that model errors should be taken into consideration in the heavy rainfall ensembles. Although the method of using different parameters in Grell scheme could not produce good results, how to construct the perturbation model or adjust the parameter in one scheme according to the physical meaning of the parameter still needs further investigation. The limitation of the current study is that it is based on a single case and more cases will be addressed in the future researches. | 陈静 薛纪善 颜宏 | 2005 | Acta meteorologica Sinica2005，19，1： | 3 |
| 18 | A Software-in-the-Loop Implementation of Adaptive Formation Control for Fixed-Wing UAVs显示文摘This paper discusses the design and software-in-theloop implementation of adaptive formation controllers for fixedwing unmanned aerial vehicles(UAVs) with parametric uncertainty in their structure, namely uncertain mass and inertia. In fact, when aiming at autonomous flight, such parameters cannot assumed to be known as they might vary during the mission(e.g.depending on the payload). Modeling and autopilot design for such autonomous fixed-wing UAVs are presented. The modeling is implemented in Matlab, while the autopilot is based on ArduPilot, a popular open-source autopilot suite. Specifically, the ArduP ilot functionalities are emulated in Matlab according to the Ardupilot documentation and code, which allows us to perform software-in-the-loop simulations of teams of UAVs embedded with actual autopilot protocols. An overview of realtime path planning, trajectory tracking and formation control resulting from the proposed platform is given. The software-inthe-loop simulations show the capability of achieving different UAV formations while handling uncertain mass and inertia. | Jun Yang Ximan Wang Simone Baldi Satish Singh Stefano Fari | 2019 | IEEE/CAA Journal of Automatica Sinica2019，6，5： | 3 |
| 19 | Co-amorphous solid dispersion systems of lacidipine-spironolactone with improved dissolution rate and enhanced physical stability显示文摘Co-amorphous solid dispersion(C-ASD)systems have attracted great attention to improve the solubility of poorly soluble drugs,but the selection of an appropriate stabilizer to stabilize amorphous forms is still a huge challenge.Herein,C-ASD system of two clinical combined used drugs(lacidipine(LCDP)and spironolactone(SPL))as stabilizers to each other,was prepared by solvent evaporation method.The effects of variation in molar ratio of LCDP and SPL(3:1,1:1,1:3,1:6,and 1:9)on the drug release characteristics were explored.Polarized light microscopy(PLM),powder X-ray diffraction(PXRD),differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA)were employed to evaluate the solid states.Prepared C-ASDs were further studied for their stability under the high humidity(RH 92.5%).Further analysis of C-ASDs via Fourier-transform infrared spectroscopy(FTIR)and Raman spectroscopy confirmed that hydrogen bond interactions between the two drugs played a significant role in maintaining the stability of the C-ASDs systems.Moreover,molecular dynamic(MD)simulations provided a clear insight into the stability mechanism at the molecular level.This study demonstrated the novel drug-drug C-ASDs systems is a promising formulation strategy for improved dissolution rate and enhanced physical stability of poorly soluble drugs. | Zhaomeng Wang Mengchi Sun Tian Liu Zisen Gao Qing Ye Xiao Tan Yanxian Hou Jin Sun Dun Wang Zhonggui He | 2019 | Asian Journal of Pharmaceutical Sciences2019，14，1： | 2 |
| 20 | Theoretical study on negative permittivity of the material producing sharp surface plasmon resonance dips显示文摘Using theoretical simulations for optical fiber surface plasmon resonance(SPR) sensors and prism-based SPR sensors coated with negative permittivity material(NPM), we investigated the effect of the permittivity of NPM on the transmitted spectrum of optical fiber SPR sensors and the reflected spectrum of prism-based SPR sensors and then obtained optimum permittivity of the NPM, which can excite the sharpest SPR spectrum in the white light region(400–900 nm). | 龚德静 袁银权 梁磊 杨明红 | 2019 | Chinese Optics Letters2019，17，4： | 2 |
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