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Poling Effects of Dielectric and Optical Properties on Pb(Zn1/3Nb2/3)1-xTixO3 Crystal

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Journal of rare Earths 2006年第Z1期24卷 166-168页

作者： Tu Chi Shun Wang Fu Tang Chien r r Hugo Schmidt V Chew L L Graduate Inst.of Applied Science and Engineering Fu Jen University Taipei 242 China Graduate Inst.of Applied Science and Engineering Fu Jen University Taipei 242 China Department of Physics Montana State University Bozeman MT 59717 USA Department of Physics Montana State University Bozeman MT 59717 USA Department of Mechanical Engineering National University of Singapore Singapore

Dipolar relaxation and dielectric/piezoelectric resonance in a (001)-cut Pb(Zn1/3Nb2/3)0.9Ti0.1O3 (PZNT10%) single crystal before and after electric (E)-field poling were presented. Dielectric permittivities were measured as functions of temperature, frequency and poling E-field strength. Frequency-dependent dielectric spectroscopy in the poled sample exhibits multiple piezoelectric resonances between 0.1 and 1 MHz, which can be described by the forced-damped-oscillator model. The resonant spectra show significant changes while phase transitions are taking place. The unpoled crystal shows almost no optical birefringence, indicating that the average structure symmetry is isotropic. Birefringence of the crystal is significantly enhanced by a prior E-field poling.

关键词： Pb(Zn1/3Nb2/3)1-xTixO3 dielectric permittivity phase transitions refractive indices

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金属塑性变形上

金属塑性变形上

Genetic Variance Estimates in Heterogeneous Potato Populations Propagated from True Potato Seed(TPS)

1989年

作者：（英）r.W.k.赫奈康

来源：汇雅图书（南通市图书馆... 评论

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中国马铃薯 2005年第2期19卷 65-69页

作者： M k Biswas M A A Mondal M Hossain r Islam Department of Botany University of RajshahiRajshahi-6205BangladeshSSOARSBurirhatRangpurBangladeshDepartment of BotanyUniversity of RajshahiRajshahi-6205BangladeshDepartment of BotanyUniversity of RajshahiRajshahi-6205Bangladesh

Twenty nine cross populations developed according to line × tester mating design along with their twelve parents raised from true potato seeds, were used to study variability and correlation for seven characters. The range of variation for all the characters were found to be wide and pronounced which indicated that characters were quantitative in nature and were under polygenic control. For all the characters, greater portion of the total δ2p was mostly contributed by the δ2g. Among the seven characters, tuber weight per plant showed the highest δ2g, PCV, GCV, H2b, GA and expected GA%. On the other hand, dry matter contents (%) showed the lowest H2b. Phenotypic and genotypic correlation coefficients of plant height with no. of tubers per plant and tuber weight per plant; no. of branches per plant with no. of tubers per plant and tuber weight per plant were found to be significant and positive.

关键词：马铃薯遗传变异评估种子繁殖相关性

Interaction of Double Sine-Gordon Solitons with External Potentials:an Analytical Model

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Chinese Physics Letters 2016年第12期33卷 18-22页

作者： S.Nazifkar k.Javidan M.Sarbishaei Physics Department University of Neyshabur Physics Department School of ScienceFerdowsi University of Mashhad

Interaction of double sine-Gordon solitons with a space dependent potential wall as well as a potential well is investigated by employing an analytical model based on the collective coordinate approach. The potential is added to the model through a suitable nontrivial metric for the background spacetime. The model is able to predict most of the features of the soliton-potential interaction. It is shown that a soliton can pass through a potential barrier if its velocity is larger than a critical velocity which is a function of the initial soliton conditions and also characters of the potential. St is interesting that the solitons of the double sine-Gordon model can be trapped by a potential barrier and oscillate there. This situation is very important in applied physics. The soliton-well system is investigated by using the presented model. Analytical results are also compared with the results of the direct numerical solutions.

关键词： of on for in been is with DSG that than line

Effect of reinforcement content on the adhesive wear behavior of Cu10Sn5Ni/Si3N4 composites produced by stir casting

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International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 1052-1060页

作者： k.Sanesh S.Shiam Sunder N.radhika Department of Mechanical Engineering Amrita School of EngineeringCoimbatore 64112Amrita Vishwa VidyapeethamAmrita UniversityIndia

The main objective of this paper was to fabricate CuSnNi alloy and its composites reinforced with various contents of SiNparticles(5wt%, 10wt%, and 15wt%) and to investigate their dry sliding wear behavior using a pin-on-disk tribometer. Microstructural examinations of the specimens revealed a uniform dispersion of SiNparticles in the copper matrix. Wear experiments were performed for all combinations of parameters, such as load(10, 20, and 30 N), sliding distance(500, 1000, and 1500 m), and sliding velocity(1, 2, and 3 m/s), for the alloy and the composites. The results revealed that wear rate increased with increasing load and increasing sliding distance, whereas the wear rate decreased and then increased with increasing sliding velocity. The primary wear mechanism encountered at low loads was mild adhesive wear, whereas that at high loads was severe delamination wear. An oxide layer was formed at low velocities, whereas a combination of shear and plastic deformation occurred at high velocities. The mechanism at short sliding distances was ploughing action of SiNparticles, which act as protrusions; by contrast, at long sliding distances, direct metal–metal contact occurred. Among the investigated samples, the Cu/10wt% SiNcomposite exhibited the best wear resistance at a load of 10 N, a velocity of 2 m/s, and a sliding distance of 500 m.

关键词： copper matrix composites stir casting adhesive wear wear mechanisms

Synthesis and electronic properties of expanded 5-(hetero)arylthien-2-yl substituted 3-ethynyl quinoxalines with AIE characteristics

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Science China Chemistry 2018年第8期61卷 909-924页

作者： Franziska k.Merkt Thomas J.J.Müller Institute of Organic Chemistry and Macromolecular Chemistry Heinrich Heine University Düsseldorf

Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Hartwig coupling of the corresponding brominated 3-ethynyl quinoxalines. Dumbbell-shaped bis(thienyl 3-ethynyl quinoxalines) are also accessible by the Suzuki protocol. The photophysical properties were investigated by UV and fluorescence spectroscopy. Most of the obtained compounds display fluorescence in solution and some of them also in the solid state. Additionally, tuning of the emission color of the quinoxaline based chromophores can be conveniently accomplished by the remote substituent group. The determined absorption and emission maximum as well as the Stokes shifts strongly correlate with Hammett σp+parameters. Besides,photophysical properties of selected derivatives in the solid state, biphasic solutions, and PMMA films, along with their relationships, are comparatively investigated. Moreover, two 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes are aggregation induced emission(AIE) chromophores indicated by restriction of molecular motions. A covalently restricted 3-ethynyl quinoxaline supports that the inhibition of molecular rotation is responsible for the significant enhancement of fluorescence in acetonitrile/water mixtures.

关键词： absorption aggregation induced emission cross-coupling fluorescence heterocycles palladium

A Gradient Model for Young's Modulus and Surface Electrode resistance of Ionic Polymer-Metai Composite

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Acta Mechanica Solida Sinica 2019年第6期32卷 754-766页

作者： H.G.Liu k.Xiong M.Wang Faculty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang 212013China State key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronauticsf Nanjing 210016China

A new model is proposed to estimate Young's modulus and surface electrode resistance of the ionic polymer-metai composite(IPMC)with a gradient distribution of micros true *** entire IPMC electrode is divided into two parts,i.e.,the porous metal electrode and the gradient polymer-metai composite electrode,according to the geometrie properties of the electroless plated metal *** validity and accuracy of the model are justified by comparing with the experimental observations of IPMC *** differences between model predictions and experimental data of Young's modulus and surface resistance of IPMC samples are+6.8%and-5.5%,respectively,indicating a reasonably good agreement.

关键词： Ionic polymer-metai composite Gradient electrode model Young's modulus resistance

Synthesis,optimization and characterization of biochar based catalyst from sawdust for simultaneous esterification and transesterification

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2654-2663页

作者： Suchith Chellappan Vaishakh Nair Sajith V. Aparna k. Department of Chemical Engineering National Institute of TechnologyCalicut India Institute of Physical Chemistry Polish Academy of Sciences School of Nano Science and Technology National Institute of Technology

The development of a benign environmental catalyst for the generation of biodiesel is an area of importance to reduce the overall usage of fossil fuels. In the current work, biochar was produced by slow pyrolysis of Irul wood sawdust. The optimization for biochar generation was carried out for different reaction temperatures and heating durations. The biochar was used to prepare solid acid catalysts by sulfonation process. The characterization of biochar and the sulfonated catalyst were carried out using Elemental analysis, Fourier Transform Infrared spectroscopy(FTIr), Powder X-ray Diffraction(XrD), Thermo Gravimetric Analysis(TGA), Scanning Electron Microscopy(SEM) and Surface area analyzer(BET). The characterization results showed that sulfonation of biochar resulted in biochar based solid acid catalyst containing various functional acidic groups like weak acidic\\OH groups, strong acidic\\COOH and SO3 H groups. The total acid density and sulfonic acid group density of catalyst were estimated and showed excellent acidic sites concentration which gives a good catalytic activity for biodiesel production through simultaneous esterification and transesterification. The enhanced catalytic activity is due to the high acid density of SO3 H groups and the reactant accessibility towards acidic sites as well as the strong affinity between the hydrophilic reactants and the neutral OH groups which are bonded with the polycyclic aromatic carbon rings. The performance of biochar catalyst for the production of biodiesel was evaluated by comparing the yield obtained. The FTIr and Gas Chromatography–Mass Spectroscopy(GC–MS) were also carried out for the analysis of biodiesel produced.

关键词： Biochar Biochar based catalyst Pyrolysis Biomass Sulfonation

Grid Voltage Sensor-less Protection Scheme for One Cycle-Controlled Single-phase Photovoltaic Inverter Systems

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1720-1729页

作者： Venkata r.reddy Sreeraj E.S. are with National Institute of Technology Goa Farmagudi Ponda 403401India

One-cycle-controlled(OCC)inverters are suitable for small single-phase photovoltaic distributed-generator systems because of their simplicity,phase-locked-loop free structure,grid voltage sensor-less operation,and *** voltage sensor-less control helps reduce cost and increases reliability in *** various sensors are used for implementation of a protection *** this paper,a grid voltage sensorless protection scheme for OCC based single-phase inverter systems is *** estimated value of voltage at point of common coupling(VPCC)is used for protecting the system during over/under voltage conditions of the grid,implementing of voltage ride through conditions,and for disconnecting the grid during islanded *** VPCC is estimated from the measured inverter current,switching pulses,and the measured dc-link voltage using a second-order *** and experimental studies are performed to verify the efficacy of the proposed voltage sensor-less protection mechanism triggered using estimated VPCC.

关键词： One cycle control photovoltaic systems voltage sensorless voltage protection over/under voltage protection islanding detection