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Search Results: 1 - 10 of 19771 matches for " X. Pei "
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ADLIF: a new large-displacement beam-based flexure joint
X. Pei ,J. Yu
Mechanical Sciences (MS) , 2011, DOI: 10.5194/ms-2-183-2011
Abstract: A flexure joint is an important component in flexure mechanisms. Most of well known flexure joints have always a trade-off among such performances as precision, stiffness, and stroke, which heavily affect the overall performances of flexure mechanisms. In this paper, a new flexure joint, named an anti-symmetric double leaf-type isosceles-trapezoidal flexure joint (ADLIF), is introduced. The joint is constructed by two leaf-type isosceles-trapezoidal flexure (LITF) building blocks in an anti-symmetrical form. In order to investigate such characteristics as precision, stiffness and stroke, two ADLIFs with different structural parameters are compared with a cartwheel hinge. In addition, a simple and accurate pseudo-rigid body (PRB) joint model of the ADLIF is formulated to simplify the parametric model and achieve the structural optimization. The results show that the ADLIF can gain a great improvement in precision as well as maintain other characteristics such as stiffness and ranges of motion similar. Even the ADLIF gets more than 16 times improvement in precision in the case that the rotational angle is less than five degrees (5°). The ADLIF can thus be used for the replacement of the cartwheel joint in some precision application fields.
Synchronous phase clustering in a network of neurons with spatially decaying excitatory coupling
Yuqing Wang,Z. D. Wang,Y. -X. Li,X. Pei
Quantitative Biology , 2001,
Abstract: Synchronization is studied in a spatially-distributed network of weekly-coupled, excitatory neurons of Hodgkin-Huxley type. All neurons are coupled to each other synaptically with a fixed time delay and a coupling strength inversely proportional to the distance between two neurons. We found that a robust, noise-resistant phase clustering state occurred regardless of the initial phase distribution. This has not been shown in previous studies where similar clustering states were found only when the coupling was inhibitory. The spatial distribution of neurons in each synchronous cluster is determined by the spatial distribution of the coupling strength. Phase-interaction properties of the model neurons in the network are used to explain why can such a clustering state be robust.
Model testing on rainfall-induced landslide of loose soil in Wenchuan earthquake region
H. Fang,P. Cui,L. Z. Pei,X. J. Zhou
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2012, DOI: 10.5194/nhess-12-527-2012
Abstract: This study investigates the formation process of rainfall-induced landslide for slopes composed of loose soil in the Wenchuan earthquake region. Experimental investigations have been performed on the landslide's formation and the variation of the controlling soil parameters under various artificial rainfall conditions. The landslide triggering mechanisms can be described in the following way. Firstly, the large porosity of the loose soil facilitated the infiltration of water, which increased the pore water pressure and reduced the shear strength of the soil significantly. In addition, the rainfalls probably caused the concentration of finer particles at a certain depth of the valley slopes. This concentration within the soil increased the pore water pressure significantly, and consequently reduced both the porosity ratio and permeability. Therefore, when the pore water pressure reached a critical state, the effective shear strength of the soil diminished, inducing the landslide's formation.
Transient heat generation in a quantum dot under a step-like pulse bias
Wei Pei,X. C. Xie,Qing-feng Sun
Physics , 2012, DOI: 10.1088/0953-8984/24/41/415302
Abstract: We study the transient heat generation in a quantum dot system driven by a step-like or a square-shaped pulse bias. We find that a periodically oscillating heat generation arises after adding the sudden bias. One particularly surprising result is that there exists a heat absorption from the zero-temperature phonon subsystem. Thus the phonon population in non-equilibrium can be less than that of the equilibrium electron-phonon system. In addition, we also ascertain the optimal conditions for the operation of a quantum dot with the minimum heat generation.
The transport properties of Floquet topological superconductors at the transition from the topological phase to the Anderson localized phase
Pei Wang,Qing-feng Sun,X. C. Xie
Physics , 2014, DOI: 10.1103/PhysRevB.90.155407
Abstract: The Floquet topological superconducting state is a nonequilibrium time-periodic state hosting Majorana fermions. We study its transport properties by using the Kitaev model with time-periodic incommensurate potentials, which experiences phase transition from the Floquet topological superconducting phase to the Anderson localized phase with increasing driving strength. We study both the real time dynamics of the current and the non-analytic behavior of the tunneling conductance at the transition. Especially, we find that the tunneling conductance changes continuously at the transition, being a finite value in the presence of Floquet Majorana fermions, but dropping to zero as the Majorana fermions vanish. For a special choice of parameters, the Majorana fermions revive at larger driving strength, accompanied by the revival of conductances.
Design of a capacitor-less low-dropout voltage regulator
X. R. Li,D. B. Pei,Q. Liu,R. Shen
Computer Science , 2014,
Abstract: A solution to the stability of capacitor-less low-dropout regulators with a 4pF Miller capacitor in Multi-level current amplifier is proposed. With the Miller compensation, a more than 50{\deg}phase margin is guaranteed in full load. An extra fast transient circuit is adopted to reduce stable time and peak voltage. When the load changes from light to heavy, the peak voltage is 40mV and chip quiescent current is only 45uA.
Enhancement of the performance of covalently immobilized lipase using alcohol quenching technology
A Wang, H Li, Z Chen, X Pei, Z Zeng, L Huang, X Yin, T Xie
African Journal of Biotechnology , 2010,
Abstract: In order to modulate the microenvironment for enzyme covalently attached on support and improve the covalent immobilization of lipase, alcohol molecules were used to quench the excessive activated functional group on support surface. Effects of kind and content of alcohol molecules on the relative activity of the immobilized enzyme and the characteristics of the immobilized enzyme were examined carefully. The maximum relative activities of the immobilized lipase quenched with methanol and npropanol, were 224.3 and 224.5%, respectively, both 1.96 fold of the just immobilized lipase which was not quenched with alcohol. Residual activity of the immobilized lipase using methanol to quench the excessive activated groups on support surface was 65.9% after heating at 50°C for 60 h, 1.29 folds higher than that of the ordinarily immobilized lipase (with no blockage). Alcohol molecules could alter the physical and chemical properties to modulate the microenvironment on support surface by changing the hydrophobicity. Suitable microenvironment, resulted from the methanol quenching the excessive active groups, would further favor the activity and the stability of lipase at higher temperature.
Why “Ding-Dong Community” Cannot Succeed Like American Version “Nextdoor”?  [PDF]
Pei Deng
Journal of Service Science and Management (JSSM) , 2015, DOI: 10.4236/jssm.2015.84065
Abstract: The conception of community O2O is very popular currently in China, which has become the focus of attention in the field of e-commerce. However, since at the preliminary exploration stage everything in this area changes very quickly, there is not yet mature business model to mimic. Many of the problems should be studied and clarified. Taking the rise and failure of “ding-dong district” as a case, this article attempts to analyze the unsuccessful reason that “ding-dong district” imitates the US version “Nextdoor” in the context of China, and put forward the corresponding countermeasures and suggestions, aiming to provide related reference for Chinese enterprises in the exploration and development of community e-commerce.
Fiber Bragg Grating Strain Sensing Detecting Multi-Crack Damages under Vibrating Status  [PDF]
Pei Luo
Optics and Photonics Journal (OPJ) , 2017, DOI: 10.4236/opj.2017.78B002
The multi-crack damages modal of simple supported beam has been build, at the vibrating status, the multi-damage detecting method of simple supported beam measured by fiber Bragg grating strain sensing array has been studied. From 0 hz to 200 hz, using exciter vibrating simple supported beam, with different damages, resonant frequency of simple supported beam has changed. So, when the damage appears in simple supported beam, the local rigidity will decrease, the resonant frequency of simple supported beam will be affected, the damage status of simple supported beam have been determined by this. The experimental result indicates that the resonant frequency of simple supported beam has changed when there is no damage, one damage, two damages, three damages on simple supported beam. According to this, the fiber Bragg grating strain sensing array can detect multi-crack damage of simple supported beam under vibrating status.
Japanese Ways of Developing Urban Underground Recreation Space  [PDF]
Pei Zhang
World Journal of Engineering and Technology (WJET) , 2018, DOI: 10.4236/wjet.2018.62030
Abstract: This paper defines the concept of urban recreation space at first, and thenfocuses on the six aspects of experience in?functional orientation, joint development, business planning, environment designing,recreational route designing, operation and management based on reviewing the development process of the underground street in urban recreation space in Japan.The results show that the overall planning and detailed design of urban recreational space in Japan is worth learning and drawing lessons for all countries in the world.
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