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some Dielectric Properties of some Resin Varnishes

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Journal of Materials science & Technology 1995年第2期11卷 119-121页

作者： s.A.El-Henawii(Faculty of science, Helwan University, Cairo, Egypt) Heiwan Univ Cairo Egypt

The dielectric constant, the dielectric loss and the power factor of three types of resins namely polyesteramide, alkyd polyesteramide and alkyd resins were measured with in the frequency range of 105 to 107 Hz and the temperature range of 20 to 50℃. The activation energy of dielectric relaxation and the entropy changes were also calculated using the usual rate equation. The results obtained are recorded and discussed.

关键词： some Dielectric Properties of some Resin Varnishes RT

Mixed H_∞ and Passive Projective synchronization for Fractional Order Memristor-Based Neural Networks with Time-Delay and Parameter Uncertainty

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Communications in Theoretical Physics 2017年第10期67卷 483-494页

作者：宋晓娜宋帅 Inés Tejado Balsera 刘磊坡 school of Information Engineering Henan University of Science and Technology Industrial Engineering school University of Extremadura

This paper investigates the mixed Ho~ and passive projective synchronization problem for fractional-order （FO） memristor-based neural networks. Our aim is to design a controller such that, though the unavoidable phenomena of time-delay and parameter uncertainty are fully considered, the resulting closed-loop system is asymptotically stable with a mixed H∞ and passive performance level. By combining active and adaptive control methods, a novel hybrid control strategy is designed, which can guarantee the robust stability of the closed-loop system and also ensure a mixed H∞ and passive performance level. Via the application of FO Lyapunov stability theory, the projective synchronization conditions are addressed in terms of linear matrix inequaiity techniques. Finally, two simulation examples are given to illustrate the effectiveness of the proposed method.

关键词： H∞ and passive performance fractional-order memristor-based neural networks adaptive pro-jective synchronization time delay uncertain parameters

Complex variable approach in studying modified polarization saturation model in two-dimensional semipermeable piezoelectric media

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Applied Mathematics and Mechanics(English Edition) 2017年第11期38卷 1517-1532页

作者： s. sINGH K. sHARMA R. R. BHARGAVA Department of sciences and Humanities National Institute of Technology UttarakhandSrinagar(Garhwal)246174India Department of Mathematics Indian Institute of Technology RoorkeeRoorkee 247667India

A modified polarization saturation model is proposed and addressed math- ematically using a complex variable approach in two-dimensional （2D） semipermeable piezoelectric media. In this model, an existing polarization saturation （Ps） model in 2D piezoelectric media is modified by considering a linearly varying saturated normal electric displacement load in place of a constant normal electric displacement load, applied on a saturated electric zone. A centre cracked infinite 2D piezoelectric domain subject to an arbitrary poling direction and in-plane electromechanical loadings is considered for the analytical and numerical studies. Here, the problem is mathematically modeled as a non-homogeneous Riemann-Hilbert problem in terms of unknown complex potential functions representing electric displacement and stress components. Having solved the Hilbert problem, the solutions to the saturated zone length, the crack opening displace- ment （COD）, the crack opening potential （COP）, and the local stress intensity factors （sIFs） are obtained in explicit forms. A numerical study is also presented for the proposed modified model, showing the effects of the saturation condition on the applied electrical loading, the saturation zone length, and the COP. The results of fracture parameters obtained from the proposed model are compared with the existing Ps model subject to electrical loading, crack face conditions, and polarization angles.

关键词： complex variable fracture parameter local stress intensity factor (sIF),piezoelectric polarization saturation (Ps) model

Heat transfer in a porous saturated wavy channel with asymmetric convective boundary conditions

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Journal of Central south University 2015年第1期22卷 392-401页

作者： Q.Hussain s.Asghar T.Hayat A.Alsaedi Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Faculty of Science King Abdulaziz University Department of Mathematics Quaid-I-Azam University 45320

The viscous flow in a wavy channel with convective boundary conditions is investigated. The channel is filled with a porous viscous fluid. Two cases of equal and different external convection coefficients on the walls are taken into account. Effect of viscous dissipation is also considered. The governing equations are derived employing long wavelength and low Reynolds number approximations. Exact closed form solutions are obtained for the simplified equations. Important physical features for peristaltic flow caused by the wavy wave are pumping, trapping and heat transfer rate at the channel walls. These are discussed one by one in depth and detail through graphical illustrations. special attention has been given to the effects of convective boundary conditions. The results show that for Bi1≠Bi2, there exists a critical value of Brinkman number Brc at which the temperatures of both the walls become equal. And, for Bi1>Bi2 and Br>Brc, the temperature of the cold wall exceeds the temperature of hot wall.

关键词： peristalsis heat transfer porous medium convective boundary conditions

Lane changing analysis for two-lane traffic flow

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Acta Mechanica sinica 2007年第1期23卷 49-54页

作者： Tieqiao Tang Haijun Huang s. C. Wong Rui Jiang Department of Automobile Engineering Beihang University Beijing 100083 China school of Management Beihang University Beijing 100083 China Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong China school of Engineering science University of Science and Technology of China Hefei 230026 China

In this paper, the two-lane traffic are studied by using the lane-changing rules in the car-following models. The simulation show that the frequent lane changing occurs when the lateral distance in car following activities is considered and it gives rise to oscillating waves. In contrast, if the lateral distance is not considered （or considered occasionally）, the lane changing appears infrequently and soliton waves occurs. This implies that the stabilization mechanism no longer functions when the lane changing is permitted. since the oscillating and soliton waves correspond to the unstable and metastable flow regimes, respectively, our study verifies that a phase transition may occur as a result of the lane changing.

关键词： Traffic flow Lane-changing rules Car-following models Flow stability

Mechanical behavior of Cu-Zr bulk metallic glasses (BMGs): A molecular dynamics approach

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Chinese Physics B 2013年第9期22卷 490-495页

作者： Muhammad Imran Fayyaz Hussain Muhammad Rashid Yongqing Cai s.A.Ahmad Department of Physics simulation Lab The Islamia University of Bahawalpur Department of Physics National University of Singapore2 Science Drive 3117542Singapore

In the present work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoinden- tation behaviors of CuZr Bulk metallic glasses （BMGs）. The substrate indenter system is modeled using hybrid interatomic potentials including both many-body Finnis sinclair （Fs） and two-body Morse potentials. A spherical rigid indenter （diameter= 60 A（1 A = 10 ^-10 m）） is employed to simulate the indentation process. Three samples of BMGs including Cu25Zr75, CusoZr50, and Cu75Zr25 are designed and the metallic glasses are formed by rapid cooling from the melt state at about 2000 K. The radial distribution functions are analyzed to reveal the dynamical evolution of the structure of the atoms with different compositions and different cooling rates. The mechanical behavior can be well understood in terms of load-depth curves and Hardness-depth curves during the nanoindentation process. Our results indicate a positive linear relationship between the hardness and the Cu concentration of the BMG sample. To reveal the importance of cooling rate provided during the processing of BMGs, we investigate the indentation behaviors of CusoZr50 at three different quenching rates. Nanoindentation results and radial distribution function （RDF） curves at room temperature indicate that a sample can be made harder and more stable by slowing down the quenching rate.

关键词： Bulk metallic glasses (BMGs) nanoindentation deformation quenching rate

Experimental study on behaviors of polypropylene fibrous concrete beams

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2007年第7期8卷 1101-1109页

作者： sUJI D. NATEsAN s. C. MURUGEsAN R. sathyabama Institute of science and Technology Chennai Tamil Nadu India VLB Janakiammal College of Engineering and Technology Coimbatore Tamil Nadu India Gojan school of Business and Technology Red Hills Chennai Tamil Nadu India

synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix’s mechanical performance is obtained so that more understanding of their structural contribution to resist cracking can be determined. This paper presents the results of an experimental investigation to determine the performance characteristics of concrete reinforced with a polypropylene structural fiber. In this investigation “Fiber mesh” brand of fibers manufactured by sL Concrete system, Tennessee, UsA and marketed by M/s Millennium Building system, Inc., Ban-galore, India are used. The lengths of the fibers used were 24 mm. Fiber dosages used were 0.9, 1.8, 2.7 kg/m3. A total of three mixtures, one for each fiber dosage were made. A standard slump cone test was conducted on the fresh concrete mix with and without fibers to determine the workability of the mix. The test program included the evaluation of hardened concrete properties such as compressive, split tensile, modulus of rupture and flexural strengths. The increase in compressive strength is about 36.25%, 26.20%, and 23.75% respectively that of plain concrete. This increase in strength was directly proportional to amount of fibers present in the mix. The increase in flexural strength for Mixes I^III is about 21%, 16.6%, and 23% respectively that of plain concrete specimens. An experimental investigation was also made to study the behaviors of reinforced fibers concrete beams (with longitudinal reinforcements) under two-point loading. The deflection and crack patterns were also studied. The improvements in strength and ductility characteristics were discussed.

关键词： Fiber Reinforcement Concrete Mechanical properties Polypropylene Fibre Reinforced Concrete (PFRC)

Localized Corrosion Characteristics of Nickel Alloys： A Review

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Acta Metallurgica sinica(English Letters) 2017年第4期30卷 296-305页

作者： Helmuth sarmiento Klapper Natalia s. Zadorozne Raul B. Rebak Center for Materials Research Baker Hughes 29221 CelleGermany Instituto de Materiales de Misiones (IMAM) UNaMCONICET 3300 Posadas Argentina GE Global Research Schenectady NY 12309 USA

There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase. Nickel alloys are generally designed for and used in highly aggressive environments, for example, those where stainless steels may experience pitting corrosion or environmentally assisted cracking. While nickel alloys are generally resistant to pitting corrosion in chloride-containing environments, they may be prone to crevice corrosion attack. Addition of chromium, molybdenum and tungsten increases the localized corrosion resistance of nickel alloys. This review on the resistance to localized corrosion of nickel alloys includes specific environments such as those present in oil and gas upstream operations, in the chemical process industry and in seawater service.

关键词： Nickel alloys Localized corrosion Oil and gas seawater Chemical process industry

Nanophase Decomposition of a Zn-Al Based Alloy Zn_(68)Al_(10)Cu_(22)

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Journal of Materials science & Technology 2004年第6期20卷 687-690页

作者： Y.H.Zhu W.B.Lee s.To Advanced Materials Research Center Department of Industrial and systems Engineering The Hong Kong Polytechnic University Hong Kong ChinaAdvanced Materials Research Center Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong ChinaAdvanced Materials Research Center Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China

The nanostructural evolution and phase transformation of the films of a Zn-Al based alloy (Zn68Al10Cu22 in wt pct) have been studied by using X-ray diffraction and scanning electron microscopy. Nanostructural thin films of the Zn-AI based alloy were produced by using an electron beam deposition technique. It was found that a nanocrystalline phase η'n had a strong preferred crystal orientation at (0002) crystal planes in the as-deposited films. During ageing at 220℃, the decomposition of nanophase η'n started with clustering to form Z-zones, and transitionai phase, which was accompanied by an eutectoid decomposition of the η'n phase: η'n β'eut T'. Decomposition, such as clustering and the formation of the Z-zones, and the transitionai phase etc. were observed in the nanophase β'eut. The formation and the decomposition of the transitionai phase of micrometers in size were involved in the decomposition of the main nanophase η'n. The mechanism of the Z-zones formation and the stability of nanophases were discussed.

关键词： Ageing Nanostructure Nanophase stability Zn-Al based alloy film