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Search Results: 1 - 10 of 328148 matches for " P. H. Lan "
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An IEEE 1547-Based Power Conditioner Test System for Distributed Energy Resources  [PDF]
Azen Y. Liu, P. H. Lan, H. H. Lin
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B181
Abstract:

Power conditioner, that is responsible for electric power conversion, is a critical component used in many renewable energy power generation systems. Most of the electric power produced by distributed energy resources cannot directly import to utility network without power conversion. Meanwhile, power conversion may includes several different types, for example AC/DC, and DC/AC, which is realized by a variety types of power conditioners in the electric power system. Currently, many concerns are focused on the operation of these power conditioners used in distributed energy resources due to the worse designing may cause the terrible influence on safety and performance characteristic of distributed energy resources. The power quality and reliability of interconnected electric power network may be affected as well. In the view of this, IEEE standards board provides a uniform standard for interconnection of distributed resources with electric power systems. It provides requirements relevant to the performance, operation, testing, safety considerations, and maintenance of the interconnection. Based on the IEEE 1547 standard, this paper presents a test system for power conditioners that are used in distributed energy resources or other renewable energy applications. Some of the test items that described in IEEE 1547.1 relevant to interconnection issues can be realized by proposed test system.

Controlling Quasibound States in 1D Continuum Through Electromagnetic Induced Transparency Mechanism
Z. R. Gong,H. Ian,Lan Zhou,C. P. Sun
Physics , 2008, DOI: 10.1103/PhysRevA.78.053806
Abstract: We study the coherent scattering process of a single photon confined in an one-dimensional (1D) coupled cavity-array, where a $\Lambda$-type three-level atom is placed inside one of the cavities in the array and behaves as a functional quantum node (FQN). We show that, through the electromagnetic induced transparency (EIT) mechanism, the $\Lambda$-type FQN bears complete control over the reflection and transmission of the incident photon along the cavity-array. We also demonstrate the emergence of a quasibound state of the single photon inside a secondary cavity constructed by two distant FQN's as two end mirrors, from which we are motivated to design an all-optical single photon storage device of quantum coherence.
Birefringence lens effects of atom ensemble enhanced by electromagnetically induced transparency
H. R. Zhang,Lan Zhou,C. P. Sun
Physics , 2008, DOI: 10.1103/PhysRevA.80.013812
Abstract: We study the optic control for birefringence of a polarized light by an atomic ensemble with a tripod configuration, which is mediated by the electromagnetically induced transparency with a spatially inhomogeneous laser. The atom ensemble splits the linearly polarized light ray into two orthogonally-polarized components, whose polarizations depend on quantum superposition of the initial states of the atom ensemble. Accompanied with this splitting, the atom ensemble behaves as a birefringent lens, which allows one polarized light ray passing through straightly while focus another orthogonal to this polarization with finite aberration of focus.
Intrinsic Cavity QED and Emergent Quasi-Normal Modes for Single Photon
H. Dong,Z. R. Gong,H. Ian,Lan Zhou,C. P. Sun
Physics , 2008, DOI: 10.1103/PhysRevA.79.063847
Abstract: We propose a special cavity design that is constructed by terminating a one-dimensional waveguide with a perfect mirror at one end and doping a two-level atom at the other. We show that this atom plays the intrinsic role of a semi-transparent mirror for single photon transports such that quasi-normal modes (QNM's) emerge spontaneously in the cavity system. This atomic mirror has its reflection coefficient tunable through its level spacing and its coupling to the cavity field, for which the cavity system can be regarded as a two-end resonator with a continuously tunable leakage. The overall investigation predicts the existence of quasi-bound states in the waveguide continuum. Solid state implementations based on a dc-SQUID circuit and a defected line resonator embedded in a photonic crystal are illustrated to show the experimental accessibility of the generic model.
PHYSICAL MODELLING OF ISOTHERMAL DIE FORGING PROCESS OF Ti-ALLOY STRUCTURAL AIR-FRAME PART WITH E TYPE CROSS-SECTION AND VARYING THICKNESS RIB
PHYSICAL MODELLING OF ISOTHERMAL DIE FORGING PROCESS OF Ti-ALLOY STRUCTURAL AIR-FRAME PART WITH ETYPE CROSS-SECTION AND VARYING THICKNESS RIB

Z K Yao,H Z Cuo,M Wang,F Lan,P F Feng,
Z. K. Yao
,H. Z. Cuo,M. Wang,F. Lan and P. F. Feng

金属学报(英文版) , 2000,
Abstract: Isothermal flashless die forging process of Ti - alloy structural air - frame part with varying thickness rib has been modelled in this paper.The results of present study show that a upside - down trapezoid rib would be formed and buckling would occure as blank is reduced,if the thickness of billet is maller than or equal to the thickness of rib. During modelling process of structural air frame part with E type cross - section rib, the saddle or lap would be formed finally at the middle of transverse rib between ribs with increase in deformation.If metal is allowed to flow out at confluence of longitudinal and transverse rib, the lop defect would be eliminated,, but a pipe cavity is obvious on corresponding loca- tion of blank. of defect formation depends on distance of metal flow ,friction,temperature homoge- neity of the blank and complexity of the part.
Quantum super-cavity with atomic mirrors
Lan Zhou,H. Dong,Yu-xi Liu,C. P. Sun,Franco Nori
Physics , 2008, DOI: 10.1103/PhysRevA.78.063827
Abstract: We study single-photon transport in an array of coupled microcavities where two two-level atomic systems are embedded in two separate cavities of the array. We find that a single-photon can be totally reflected by a single two-level system. However, two separate two-level systems can also create, between them, single-photon quasi-bound states. Therefore, a single two-level system in the cavity array can act as a mirror while a different type of cavity can be formed by using two two-level systems, acting as tunable "mirrors", inside two separate cavities in the array. In analogy with superlattices in solid state, we call this new "cavity inside a coupled-cavity array" a super-cavity. This supercavity is the quantum analog of Fabry-Perot interferometers. Moreover, we show that the physical properties of this quantum super-cavity can be adjusted by changing the frequencies of these two-level systems.
The Synthesis of Solvent-Free TiO2 Nanofluids through Surface Modification  [PDF]
P. Y. Yu, Y. P. Zheng, L. Lan
Soft Nanoscience Letters (SNL) , 2011, DOI: 10.4236/snl.2011.12008
Abstract: TiO2 nanoparticles with surface hydroxyl groups are treated by trimethoxysilane (CH3O)3Si(CH2)3O(CH2CH2O)6-9CH3 and a inorganic core/organic shell hybridmaterials, which shows itself a yellow viscous fluid, is obtained. We call it solvent-free TiO2 nanofliuds. Transmission electron microscopy (TEM), Fourier transform infrared spectrum (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and rheometer are adopted to characterize the product. As a result, the content of TiO2 nanoparticles in the nanofliuds is about 5.5wt%, the functionalized TiO2 nanoparticles possess better dispersion, very low viscosity and an obvious liquid-like behavior at room temperature in absence of solvent.
Development of instrumentation for amperometric and coulometric detection using ultramicroelectrodes
Coutinho, Cláudia F. B.;Coutinho, Lincoln F. M.;Lan?as, Fernando M.;Camara, Carlos A. P.;Nixdorf, Suzana L.;Mazo, Luiz H.;
Journal of the Brazilian Chemical Society , 2008, DOI: 10.1590/S0103-50532008000100019
Abstract: in this work it is presented the development of a simple, portable and inexpensive instrumentation for amperometric and coulometric detection in different analytical instrumentation systems utilizing ultramicroelectrodes. the software, developed in labview 7.1tm, is capable to carry out three main detection techniques (amperometric, pulsed amperometric and coulometric detection) and a voltammetric technique (cyclic voltammetry). the instrumentation was successfully evaluated using the following systems: cyclic voltammograms of metallic electrodes in alkaline solutions, flow electrochemical detection of glucose and glycine and direct determination of herbicide glyphosate (electrochemical detection coupled to hplc).
Bivariate Rainfall and Runoff Analysis Using Entropy and Copula Theories
Lan Zhang,Vijay P. Singh
Entropy , 2012, DOI: 10.3390/e14091784
Abstract: Multivariate hydrologic frequency analysis has been widely studied using: (1) commonly known joint distributions or copula functions with the assumption of univariate variables being independently identically distributed (I.I.D.) random variables; or (2) directly applying the entropy theory-based framework. However, for the I.I.D. univariate random variable assumption, the univariate variable may be considered as independently distributed, but it may not be identically distributed; and secondly, the commonly applied Pearson’s coefficient of correlation (g) is not able to capture the nonlinear dependence structure that usually exists. Thus, this study attempts to combine the copula theory with the entropy theory for bivariate rainfall and runoff analysis. The entropy theory is applied to derive the univariate rainfall and runoff distributions. It permits the incorporation of given or known information, codified in the form of constraints and results in a universal solution of univariate probability distributions. The copula theory is applied to determine the joint rainfall-runoff distribution. Application of the copula theory results in: (i) the detection of the nonlinear dependence between the correlated random variables-rainfall and runoff, and (ii) capturing the tail dependence for risk analysis through joint return period and conditional return period of rainfall and runoff. The methodology is validated using annual daily maximum rainfall and the corresponding daily runoff (discharge) data collected from watersheds near Riesel, Texas (small agricultural experimental watersheds) and Cuyahoga River watershed, Ohio.
Modelling galaxy stellar mass evolution from z~0.8 to today
Lan Wang,Y. P. Jing
Physics , 2009, DOI: 10.1111/j.1365-2966.2009.16007.x
Abstract: We apply the empirical method built for z=0 in the previous work of Wang et al. to a higher redshift, to link galaxy stellar mass directly with its hosting dark matter halo mass at z~0.8. The relation of the galaxy stellar mass and the host halo mass M_infall is constrained by fitting both the stellar mass function and the correlation functions at different stellar mass intervals of the VVDS observation, where M_infall is the mass of the hosting halo at the time when the galaxy was last the central galaxy. We find that for low mass haloes, their residing central galaxies are less massive at high redshift than those at low redshift. For high mass haloes, central galaxies in these haloes at high redshift are a bit more massive than the galaxies at low redshift. Satellite galaxies are less massive at earlier times, for any given mass of hosting haloes. Fitting both the SDSS and VVDS observations simultaneously, we also propose a unified model of the M_stars-M_infall relation, which describes the evolution of central galaxy mass as a function of time. The stellar mass of a satellite galaxy is determined by the same M_stars-M_infall relation of central galaxies at the time when the galaxy is accreted. With these models, we study the amount of galaxy stellar mass increased from z~0.8 to the present day through galaxy mergers and star formation. Low mass galaxies gain their stellar masses from z~0.8 to z=0 mainly through star formation. For galaxies of higher mass, the increase of stellar mass solely through mergers from z=0.8 can make the massive galaxies a factor ~2 larger than observed at z=0. We can also predict stellar mass functions of redshifts up to z~3, and the results are consistent with the latest observations.
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