Papers by Keyword: Stability

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Authors: Jian Hua Liu
Abstract: Combined with the highway from Lixian to Xiaojin, the in-situ monitoring test for Baozizui rock slope was carried out in Li County earthquake zone of Sichuan province, and three earthquakes whose magnitude exceeds 4.8 times had occurred during the monitoring period. According to monitoring results, the main conclusion was shown that the slope deformation attenuated and tended to be stable after two month of construction. Considered the anti-inclined structural face in the slope, the compacting deformation action, which was beneficial to slope stability. Moreover, seismic load had great influence on horizontal deformation of structural face in surface rock layer. And the reason was that there was regional stress bearing compression and shear in the nappe structures located on the thrust fault upper plate of this slope. The variation of horizontal deformation was frequent in earlier stage located at the road curve, in which there existed the traffic load, seismic excitation effects. And the later observational data indicated that the deformation has been basically stabilized.
Authors: Adrian Ioan Niculescu
Abstract: The paper presents a complex quarter car model obtained with ADAMS software, View module, useful in the first stage of suspension dimensioning and optimization.The model is equipped with compression and rebound stopper buffer and suspension trim corrector.The proposed quarter car model with two degrees of freedom (wheel and body) performs all these goals allowing changing:Geometrical elementsPosition of equilibrium, depending on vehicle load;Trim correction;Elastic and dissipative characteristics of the suspension and tire;Suspension stroke;Road profile, assessed either by simple or summation of harmonic functions or reproducing real roadsBuffers (for stroke limitation) position and characteristics;The models developed provide information on:Vertical stability assessed by vertical movements of the body and the longitudinal and transversal stability evaluated based on adherence characterized by wheel ground contact force and frequency of soil detachment wheel.Comfort assessed on the basis of body vertical acceleration and collision forces to the stroke ends.The body-road clearanceThe trim corrector efficiencyAll above performances evaluated function the road unevenness, acceleration, deceleration, turning regime.The damping characteristic is defined by damping forces at different speed for each strokes respectively one for rebound and other for compression.The contact force road-wheel is defined based tire rigidity law.The stopper buffer forces on rebound and compression are defined based each specific rigidity characteristics.The road excitation is realized with a function generator.The software allow the model evolution visualisation in real time, also generating the diagrams of displacements, forces, accelerations, speeds, for each elements or for relative evolution between diverse elements.The simulation was realized for unloaded and fully loaded car using a road generated by a sum of harmonic functions presented in equation (8).The excitation covers the specific frequencies area, being under the body frequencies up to the wheel proper frequencies.The realized ¼ car model, have reached the goal to evaluate the suspension trim correction advantages.The simulations confirm the trim corrector increases the suspension performances, thus for the analyzed case the trim corrector increase simultaneous:Body-ground clearance (evaluated by body higher increasing) between 18.5÷55.1 %Body stability (evaluated by maximal body displacement) between 9.8÷11.4 %Body comfort (evaluated by maximal body acceleration) between 3.4÷35.5 %Adherence (evaluated by maximal and RMS wheel-groundcontact force variation) between 7.0÷12.1 %Body and axles protection (evaluated by buffer strike force) between 10.8÷38.2 %
Authors: Zong Kun Li, Yu Rong Huang, Jian You Wang, Qiang Zi
Abstract: In order to simulate the seepage field with drain pipes, the air element method is used in this paper. In this method, the pipe elements are regarded as a kind of material with high permeability coefficient and an equivalent hydraulic conductivity is assigned to them. Thus these pipe elements can be included in the conventional seepage calculation as other common elements. Moreover, the difficulty of giving water head boundary to the inner surface of pipes directly is avoided. According to the seepage calculation of the channel with large number of drain pipes in Huangyou part of the middle line in South-to-North water transfer project, the results show that, with drainage-piping, the pore water pressure in channel foundation is reduced significantly.
Authors: Bi Hong Song, Jin Chao Yang, Qing Chen, Jian Hua Chen, Da Li
Abstract: The sedimentation deformation of superhigh fill in the mountainous areas is very complicated in law, and will be influenced the topographic relief, and it is specially outstanding for the sedimentation of high-fill project. For the significant project such as airport and road base, in order to guarantee the safe operation of the project during use, it is required to strictly control the post-construction and uneven sedimentation. Therefore, the stability of superhigh fill has become the key to influence the safety and stable operation of projects. In this paper, a simulated calculation is conducted to the ultrahigh fill of expansion project of an airport in Chongqing to analyze its stability, so as to provide references for the project design and construction.
Authors: Lih Jier Young, Pau Lo Hsu, Syh Shiuh Yeh, Yu Fang Cheng
Abstract: Circular ring is the most popular specimen in industry. The location of a crack in a circular ring can strongly affect the sequence of plastic hinge development which in turn affects stability of a circular ring which has been obtained theoretically in Young [1] but not any numerically. Boundary element method is employed to investigate these effects. In fact, the ring will collapse if the number of plastic hinges is up to four. The results show the potential application of the boundary element method in this project.
Authors: Bai Tao Lv, Rui Xing Li, Jiafeng Zhu, Na Bai, Xiu Long Wu
Abstract: This paper describes a circuit which can enhance the robustness of the subthreshold 6T SRAM bitcell. The proposed circuit can dynamically adjust the body voltages of the PMOS transistors in order to enhance the robustness of the subthreshold 6T SRAM bitcell by detecting the variation of the threshold voltage. The simulation results under 300mV in 65nm technology demonstrate that the mean values of the read and hold static noise margin (SNM) of the subthreshold 6T SRAM bitcell have been improved by 18% and 0.7%, respectively, meanwhile the standard values of the read and hold SNM have improved by 82% and 29.4%, respectively, by adopting the proposed circuit. Moreover, the proposed circuit functions well in a wide range of supply voltage from 0.2V to 0.5V.
Authors: Jian Mei Luo, Yu Ming Feng
Abstract: This paper considered two organisms competing for a nutrient in the chemostat in the presence of an inhibitor, where the yields and growth rates are general increasing function of the nutrient concentration. The inhibitor is produced by one organisms and is lethal to the other organism. By the theory of qualitative analysis for ordinary equations, first, conditions of the existence and local stability of the rest points are obtain; then the global asymptotical stability, the existence of limit cycles and Hopf bifurcation are discussed.
Authors: Qing Xiang Gao, Lin Xu, Bo Wu
Abstract: The spin-polarized generalized gradient approximation to the density functional theory is used to determine the geometries, stability, electronic structures, and magnetic properties of the Gd8O12 cluster. Our work reveals that the ground state configuration of the Gd8O12 cluster is a hexahedral cage structure with Ci symmetry. The electronic and magnetic properties imply that the formations of the ionic bonds between the adjacent Gd and O atoms result in the high stability of the Gd8O12 cluster, which is due to the charge transfers between the Gd 5d, 6s electrons to O 2p orbital. It is also confirmed by the electron densities of HOMO-LUMO states. In addition, the analysis of the magnetic properties implies the total magnetic moments are mostly dominated by the Gd 4f orbital.
Authors: Shuai Qin Yu, Hong Nan Ye
Abstract: Geometric structures of Fe6-xSix(x=1-5) clusters have been systematically studied at the BPW91 level by density-functional theory (DFT). Calculated results show that the Fe atoms of the lowest-energy structures of Fe6-xSix clusters tend to go together, and Si atoms tend to occupy surface site bonding with iron atoms as many as possible. Further, we analyze the stability of the lowest-energy structures of Fe6-xSix clusters, and the corresponding results of the HOMO, LUMO as well as the HOMO-LUMO energy gap show that the Fe5Si and Fe4Si2 clusters have special stability.
Authors: Hai Ying Hu, Xiao Wen Zhou, Zhi Xing Huang
Abstract: The soft soil in Pearl River Delta regions is characterized with high water content, high compressibility and low bearing capacity. Therefore, when building the structures on such foundation, it’s necessary to pay attention to the deformation and stability. The projects' practice shows that, when analyzing the stability on foundation pit or slope with soft interlayer, it should not only calculate the overall stability of the slope, but also calculate the stability or bearing capacity of the foundation. Although sometimes the stability of the slope meets the requirements, it doesn’t means that the bearing capacity of the foundation meets the requirements because of the existence soft interlayer, the limitations of the circle slice method and the difference between the sliding surface and the actual sliding surface.
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