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Oscillation control for n-dimensional congestion control model via time-varying delay

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Science China(Technological Sciences) 2011年第8期54卷 2044-2053页

作者： ZHAnG Shu XU Jian school of Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 China

Time delay or round trip time (RTT) is an important parameter in the model of Internet congestion control. On the one hand, the delay may induce oscillation via the Hopf bifurcation. In the present paper, a congestion control model of n dimensions is considered to study the delay-induced oscillation. By linear analysis of the n-dimensional system, the critical delay for the Hopf bifurcation is obtained. To describe the relation between the delay and oscillation analytically, the method of multiple scales (MMS) is employed to obtain the bifurcating periodic solution. On the other hand, it can be understood that the oscillation will increase the risk of congestion for the network system. To avoid the congestion derived from the oscillation, a new control scheme is proposed by perturbing the delay periodically. Particularly, according to our study, it is possible to control the oscillation by perturbing only one of the n delays. This provides a practical scheme for the oscillation control in the real network system. By MMS, the strengths of the perturbations are predicted analytically such that the oscillation disappears. To give an example, an eight-dimensional model is studied in detail. The analytical results are in good agreement with the numerical simulations.

关键词： internet congestion control high-dimensional system Hopf bifurcation time-varying delay method of multiple scales

Geochemistry of a paleosol horizon at the base of the Sausar Group,central India： Implications on atmospheric conditions at the Archeane Paleoproterozoic boundary

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Geoscience Frontiers 2016年第5期7卷 759-773页

作者： Sarada P.Mohanty Sangitsarita nanda Department of Applied Geology. Indian school of Mines Dhanbad 826004 India

A paleosol horizon is described from the contact of the Sausar Group（w2400 Ma） and its basement（Tirodi Gneiss; 〉2500 Ma） in Central India. Physical evidence of pedogenesis is marked by the development of stress corrosion cracks, soil peds, corestone weathering and nodular rocks. XRD and SEM-EDX data indicate the presence of siderite, ankerite, uraninite, chlorite, alumino-silicate minerals, ilmenite,rutile and magnetite, in addition to quartz, feldspar and mica. The chemical index of alteration, the plagioclase index of alteration, and the chemical index of weathering show an increasing trend from parent rock to the paleosol and indicate a moderate trend of weathering. The A-Cn-K plot indicates loss of feldspars, enrichment in Al2O3 and formation of illite. Different major element ratios indicate baseloss through hydrolysis, clay formation, leaching of some elements, and more precipitation with good surface drainage. The paleosol is depleted in HREE in comparison to the parent rock indicating high fluid-rock interaction during weathering. The paleosol samples show flat Ce and Eu anomalies, low SREE, and high（La/Yb）n, indicative of a reducing environment of formation. Reducing condition can also be inferred from the concentration of elements such as V, Co, Cu, Pb, and Zn in the paleosol profile. Although enriched in Fe and Mg, the overall geochemical patterns of the paleosol indicate oxygen deficient conditions in the atmosphere and development by weathering and leaching processes associated with high precipitation and good surface drainage at the time of development of this paleosol during the Archeane Paleoproterozoic transition.

关键词： Paleosol Anoxic weathering Great oxidation event Paleoproterozoic Sausar Group

Exchange bias on polycrystalline BiFeO3/CO2Fe(Al0.5Si0.5) heterostructures

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Rare Metals 2017年第1期36卷 32-36页

作者： Shi-Zhe Wu Yong Wu Shao-Qian Yin Xiao-Guang Xu Jun Miao Yong Jiang school of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Polycrystalline antiferromagnetic BiFeO(BFO)thin films were grown on Si/Si O/Ti/Pt(111) substrates by pulsed laser deposition and then ferromagnetic films CoFe(AlSi)(CFAS) by magnetron sputtering. After fabrication, the films were vacuum-annealed under a 0.1-T magnetic field at different temperatures from 150 to 500 °*** exchange bias field can be tuned by the annealing temperature for the heterostructures, and the electric domain size can be controlled by the crystal grain size. A large exchange bias of about 5*10T is observed in one of the samples. It can be speculated that the crystal grain sizes are the key element in determining the exchange bias and coercivity of the films annealed at the temperature of higher than neel temperature(T n) of BFO. Furthermore, it is possible to extend spin theories from single-crystal BFO system to polycrystalline BFO system.

关键词： Exchange bias BiFeO3 Polycrystalline Domain walls

The Preparation and Characterization of Amorphous SiCn Thin Films

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Wuhan University Journal of natural Sciences 2001年第3期6卷 665-669页

作者： Li Jin chai, Lu Xian feng, Zhang Zi hong, Guo Huai xi, Ye Ming sheng school of Physics and Technology, Wuhan University, Wuhan 430072, China school of Physics and Technology Wuhan University Wuhan China

Radio Frequency plasma enhanced Chemical Vapor Deposition (RF CVD) using n2, SiH4 and C2H4 as the reaction sources was used to prepare amorphous ternary Si x C y n z thin films. The chemical states of the C, Si and n atoms in the films were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR). The refractive indexn, extinction coefficientk and optical band gapE opt of the thin films were investigated by UV-visible spectrophotometer and spectroscopic ellipsometer. The results show that a complex chemical bonding network rather than a simple mixture of Si3n4, SiC, Cn x and a-C etc., may exist in the ternary thin films. Then's of the films are within the range of 1. 90–2. 45, andE opt's of all samples are within the range of 2. 71–2. 86 eV.

关键词： SiCn thin films RF CVD synthesis optical properties X ray photoelectron spectroscopy (XPS) FTIR

Microstructure and Mechanical Property of Magnetron Sputtering Deposited DLC Film

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Journal of Wuhan University of Technology(Materials Science) 2018年第3期33卷 579-584页

作者：孙泽 ZHAO Wen 孔德军 school of Mechanical Engineering Changzhou University College of Mechanical Engineering Donghua University

A diamond-like carbon（DLC） film was deposited on YT14 substrate using magnetron sputtering（MS）. The surface morphologies, roughness and bonding spectra of obtained film were characterized using scanning electron microscopy（SEM）, atomic force microscopy（AFM）, and X-ray photoelectron spectroscopy（XPS）, respectively, and its mechanical property and bonding strength were measured using a nanoindentation and scratch tester, respectively. The results show that the C-enriched DLC film exhibits a denser microstructure and smoother surface with lower surface roughness of 21.8 nm. The ratio of C sp2 at 284.4 e V that corresponds to the diamond（111） and the C sp3 at 285.3 e V that corresponds to the diamond（220） plane for the as-received film is 0.36： 0.64, showing that the C sp3 has the high content. The hardness and Young＇s modulus of DLC film by nanoindentation are 8.534 41 and 142.158 1 GPa, respectively, and the corresponding bonding strength is 74.55 n by scratch test.

关键词： diamond-like carbon(DLC) film magnetron sputtering(MS) atomic force microscope (AFM) X-ray photoelectron spectroscopy(XPS) nanoindentation

Some generalized limit theorems concerning delayed sums of random sequence

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Applied Mathematics(A Journal of Chinese Universities) 2013年第1期28卷 40-48页

作者： WAnG Zhong-zhi YAnG Wei-guo SHI Zhi-yan school of Mathematics & Physics AnHui University of Technology Faculty of Science Jiangsu University

For a sequence of arbitrarily dependent m-valued random variables （Xn） n∈n , the generalized strong limit theorem of the delayed average is investigated. In our proof, we improved the method proposed by Liu [6] . A... 详细信息

关键词： Limit theorem delayed average Borel-Cantelli lemma inhomogeneous Markov chain.

Escape and Stand of the Pluto Atmosphere

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Communications in Theoretical Physics 2002年第7期38卷 125-127页

作者： GAO Chong-Yi school of Physical Science and Technology Lanzhou University Lanzhou 730000 China

Molar mass μmin of the lightest gas, which will exist "forever" in the atmosphere at the planet surface,can be evaluated by Jeans rule. The μmin of Pluto is 17.3 g@ mol-1. It is evident that both n2 and CO can be major atmospheric composition at the Pluto surface, and will exist "forever". CH4 can only be escaping slowly from Pluto atmosphere, and still holds quite a proportion in current Pluto atmosphere. However, it will not escape from Titan (or Jupiter, Saturn) atmosphere largely, and will exist "forever". Given the quantitylevelof partial pressure of CH4 in Pluto and Titan (or Jupiter, Saturn) original atmosphere is the same, it will be clear that the current partial pressure of CH4 in Pluto surface atmosphere is 10-3 Pa.

关键词： planet atmosphere, Pluto atmosphere, Jeans rule, atmospheric composition, escape

Equilibrium of hydroxyl complex ions in Pb^(2+)-H_2O system

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中国有色金属学会会刊：英文版 2009年第2期19卷 458-462页

作者：王云燕柴立元常皓彭小玉舒余德 school of Metallurgical Science and Engineering Central South University Tianjin Pipe(Group) Corporation

The thermodynamics equilibrium principle was used to construct the diagrams for the concentration of complex ions(pc) vs pH,the distribution ratio of lead hydroxyl complex ions(αn) vs pH,and the conditional solubility product of Pb(OH)2 vs pH in the Pb2+-H2O system. The relationship between the equilibrium concentration of each kind of lead hydroxyl complex ions in equilibrium with Pb(OH)2(s) and pH value was shown in the system. The minimum solubility of lead is at the pH value of 10.096-10.997. The distribution ratio of each kind of the lead hydroxyl complex ions is determined as a function of the pH value and the total lead concentration([Pb]T). The diagram for the conditional solubility product,pKSP vs pH,shows that each kind of lead hydroxyl complex ions existing in the system is dependent upon an optimized pH value at the established concentration of [Pb]T,and that pKSP reaches the minimum at the pH value of 10.3-11.2. The results can provide a theoretical basis for removing lead ions from wastewater by the neutralization and hydrolyzation technology.

关键词：离子浓度热力学平衡铅浓度 H2O 羟基条件溶度积 pH值显示系统

Helical secondary structures and supramolecular tilted chirality in n-terminal aryl amino acids with diversified optical activities

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Chinese Chemical Letters 2021年第4期32卷 1390-1396页

作者： Zhuoer Wang Aiyou Hao Pengyao Xing school of Chemistry and Chemical Engineering Shandong UniversityJi'nan 250100China

Helix structures at atomic/molecular level have not been found in self-assembled peptide seque nce with less than three ***β-sheet supramolecular secondary structures have been discovered in solidstate amino acids,we here report the conjugation of simple n-terminal aryl protecting group could give rise to helical supramolecular secondary structures in solid-state,which determines the optical activities of the adjacent aryl *** carboxylic acid-involved asymmetric H-bonds in n-te rminal aryl amino acids induce the emergence of super-helical structures of amino acid residues and aryl *** most cases,supramolecular tilted chirality of aryl groups is opposite to that of amino acid sequences,of which handedness and helical pitch are determined by the H-bond *** correlation between supramolecular tilted chirality of aryl segments and their chiroptical activities is firstly unveiled,which was verified by the computational results based on density functional *** aryl amino acids self-assembled by nanoprecipitation method via crystallization induced self-assembly into rigid one-dimensional microstructures with ultra-high Young's *** study reveals the generic existence of chiral supramolecular structure s in aggregated amino acid derivatives and gives an in-depth investigation into the structural-property relationships,which could guide the rational design and screening of chiroptical supramolecular materials.

关键词： Amino acids Self-assembly Chirality Chiroptical properties H-bonds