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Non-smooth bifurcations in a double-scroll circuit with periodic excitation

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Chinese Physics B 2011年第1期20卷 186-193页

作者：张银毕勤胜 faculty of Science Jiangsu University

The fast-slow effect can be observed in a typical non-smooth electric circuit with order gap between the natural frequency and the excitation frequency. Numerical simulations are employed to show complicated behaviours, especially different types of busting phenomena. The bifurcation mechanism for the bursting solutions is analysed by assuming the forms of the solutions and introducing the generalized Jacobian matrix at the non-smooth boundaries, which can also be used to account for the evolution of the complicated structures of the phase portraits with the variation of the parameter. Period-adding bifurcation has been explored through the computation of the eigenvalues related to the solutions. At the non-smooth boundaries the so-called ＇single crossing bifurcation＇ can occur, corresponding to the case where the eigenvalues jump only once across the imaginary axis, which leads the periodic burster to have a quasi-periodic oscillation.

关键词： Matsumoto's circuit non-smooth bifurcation fast-slow effect bursting

The sol-gel derived Co-Mn/TiO_2 catalysts for light olefins production

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燃料化学学报 2014年第2期42卷 212-218页

作者： Mohammad Mehdi Khodaei Mostafa Feyzi Jahangir Shahmoradi Mohammad Joshaghani faculty of Chemistry Razi University

在这个研究工作，二 30%(Co-Mn )/TiO2 催化剂用大音阶的第五音胶化(催化剂 A ) 和一起沉淀(催化剂 B ) 被准备方法。到在 Fischer-Tropsch 合成(英尺) 的 C24 轻石蜡的活动和选择在不同运作的条件下面在一个改正床反应堆被学习了。这... 详细信息

在这个研究工作，二 30%(Co-Mn )/TiO2 催化剂用大音阶的第五音胶化(催化剂 A ) 和一起沉淀(催化剂 B ) 被准备方法。到在 Fischer-Tropsch 合成(英尺) 的 C24 轻石蜡的活动和选择在不同运作的条件下面在一个改正床反应堆被学习了。这些运作的条件是：温度

关键词： Fischer-Tropsch synthesis light olefins characterization

EFFECT OF SURFACE MODIFICATION OF MONTMORILLONITE ON THE PROPERTIES OF RIGID POLYURETHANE FOAM COMPOSITES

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Chinese Journal of Polymer Science 2010年第4期28卷 615-624页

作者：彭懋 faculty of Engineering Zhejiang University

This study investigated the influence of various organically modified montmorillonites （organoclays） on the structure and properties of rigid polyurethane foam （RPUF） nanocomposites. The organoclays were modified with cetyltrimethyl ammonium bromide （CTAB）, methyl tallow bis（2-hydroxyethyl） quaternary ammonium chloride （MT2ETOH） and tris（hydroxymethyl）aminomethane （THMA） and denoted as CMMT, Cloisite 30B and OMMT, respectively. MT2ETOH and THMA contain hydroxyl groups, while THMA does not have long aliphatic tail in its molecule. X-ray diffraction and transmission electron microscopy show that OMMT and Cloisite 30B can be partially exfoliated in the RPUF nanocomposites because their intercalating agents MT2ETOH and THMA can react with isocyanate. However, CMMT modified with nonreactive CTAB is mainly intercalated in the RPUF matrices. At a relatively low filler content, the RPUF/CMMT composite foam has a higher specific compressive strength （the ratio of compressive strength against the apparent density of the foams）, while at relatively high filler contents, RPUF/Cloisite 30B and RPUF/OMMT composites have higher specific compressive strengths, higher modulus and more uniform pore size than the RPUF/CMMT composite.

关键词： Organoclay Rigid polyurethane foam Nanocomposite Mechanical properties

Noise composed of multiplication of two dichotomous noises

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Chinese Physics B 2008年第6期17卷 1990-1997页

作者：李静辉 faculty of Science Ningbo University

In this paper, we introduce a noise which is composed of multiplication of two dichotomous noises, and derive the probability density and the statistical properties of this noise. The obtained results can help study the resonant activation phenomenon, the phenomenon of stochastic resonance, the transport of particles, and the nonequilibrium （phase） transition for the systems driven by this noise.

关键词： Dichotomous noise probability density statistical properties

Modified coupled map car-following model and its delayed feedback control scheme

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Chinese Physics B 2011年第9期20卷 69-76页

作者：葛红霞 faculty of Science Ningbo University

A modified coupled map car-following model is proposed, in which two successive vehicle headways in front of the considering vehicle is incorporated into the optimal velocity function. The steady state under certain conditions is obtained. An error system around the steady state is studied further. Moreover, the condition for the state having no traffic jam is derived. A new control scheme is presented to suppress the traffic jam in the modified coupled map car-following model under the open boundary. A control signal including the velocity differences between the following and the considering vehicles, and between the preceding and the considering vehicles is used. The condition under which the traffic jam can be well suppressed is analysed. The results are compared with that presented by t^onishi et al. （the KKH model）. The simulation results show that the temporal behaviour obtained in our model is better than that in the KKH model. The simulation results are in good agreement with the theoretical analysis.

关键词： traffic flow coupled map carwfollowing model optimal velocity function delayed feed-back control

Coatings on Mg alloys and their mechanical properties: A review

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Journal of Materials Science & Technology 2018年第7期34卷 1119-1126页

作者： Toko Tokunaga Munekazu Ohno Kiyotaka Matsuura faculty of Engineering Hokkaido University

Poor corrosion resistance is a serious drawback of Mg alloys, restricting their practical applications. Coating is one of the effective techniques for improvement in the poor corrosion resistance. In this paper, the coating processes for Mg alloys so far developed are reviewed. Among several processes, the coating processes based on mechanical energy, including metal forming, are attractive because the corrosion resistance and formability of Mg alloys are simultaneously improved.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

关键词： Magnesium alloy Coating Mechanical property Corrosion resistance

Environmental chemical study on the marsh of Fatimid cemetery at Aswan City, Egypt

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Journal of Environmental Sciences 2002年第4期14卷 464-473页

作者： M.E.Soltan Chemistry Department Faculty of Science

Environmental chemical study were carried out on the Fatimid cemetery marsh at Aswan City(24°1'N and 32°9'E), Egypt. Marsh contents(warter, soil, sediment, metal and nonmetal bearing salts, and emergent weed) were analysed to known the source of marsh water, speciation of the different elements between the marsh contents, and the toleration of emergent weed (Phargmites australies) for different metals and their bioaccumulation coefficients. Thus, metals(Ca, Mg, Na, K, Ni, Fe, Mn, Cu, Zn, Cd and Pb) and nonmetals(CO 2- 3, HCO - 3, Cl -, SO 2- 4, PO 3- 4, NO - 3, SiO 2, organic matter and pH value) were determined in the samples. According to the chemical analysis, and applying the base exchange equation(water type) and calculate the hydrochemical parameters for marsh water samples, we can indicate that the marsh water is ground water with Na SO 4 type and deep meteoric genesis. Topsoil of marsh dry land characterized by CaCl as dominant salt,while NaCl is a dominant salt in subsoil. The elevated pH values of marsh contents minimized the metal solubilities in different samples. Phragmites australies showed a strong ability to accumulate Mn and Fe in the aerial part in opposite to Co, Ni and Cd.

关键词： marsh water soil sediment emergent weed Egypt

Vanadium oxide nanotubes for selective catalytic reduction of NO_x with NH_3

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Chinese Journal of Chemical Engineering 2016年第7期24卷 914-919页

作者： Seyed Mahdi Mousavi faculty of Chemistry University of Kashan

Vanadium oxide （VOx） nanostructures, synthesized by hydrothermal treatment using dodecylamine as template, were evaluated for the selective catalytic reduction of NOx with ammonia （NH3-SCR）, The effect of solvent type in the reaction mixture （EtOH/（EtOH ＋ H20）） and time of hydrolysis was studied. The obtained materials were characterized by XRD, SEM, TEM and BET, The VOx nanorods （80-120 nm diameter and 1-4 μm length） were synthesized in 25 vol% EtOH/（EtOH ＋ H20） and the open-ended multiwalled VOx nanotube （50-100 nm inner diameter, 110-180 nm outer diameter and 0,5-2 pm length） synthesized in 50 vol% EtOH/（EtOH ＋ H20）. VOx nanotuhes performed the superior NH3-SCR activity under a gas hourly space velocity of 12,000 h-1 at low temperature of 250 ~C （NOx conversion of 893g ＆ N2 selectivity of 100%）, while most of the developed Vanadia base catalysts are active at high temperature （〉350 ℃）. The superior NH3-SCR activity ofVOx nanotubes at low tem- perature is related to nanocrystalline structure, special nanotube morphology as well as high specific surface area.

关键词： Hydrothermal Nanotubes NOx Pollution SCR

Finite temperature effect on mechanical properties of graphene sheets with various grain boundaries

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Chinese Physics B 2016年第6期25卷 332-337页

作者：葛勇孙宏祥管义钧曾赣鹤 faculty of Science Jiangsu University

The mechanical properties of graphene sheets with various grain boundaries are studied by molecular dynamics method at finite *** finite temperature reduces the ultimate strengths of the graphenes with different types of grain *** interestingly,at high temperatures,the ultimate strengths of the graphene with the zigzagorientation grain boundaries at low tilt angles exhibit different behaviors from those at lower temperatures,which is determined by inner initial stress in grain *** results indicate that the finite temperature,especially the high one,has a significant effect on the ultimate strength of graphene with grain boundaries,which gives a more in-depth understanding of their mechanical properties and could be useful for potential graphene applications.

关键词： graphene grain boundary temperature molecular dynamics