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Tunable passively Q-switched ytterbium-doped fiber laser with mechanically exfoliated GaSe saturable absorber

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Chinese Optics Letters 2018年第2期16卷 93-97页

作者： H.Ahmad S.N.Aidit S.I.Ooi Z.C.Tiu Photonics research centre University of Malaya

A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is *** few-layer GaSe SA,which is fabricated by the mechanical exfoliation method,is able to generate a Q-switched fiber laser that has a maximum repetition rate of 92.6 kHz and a minimum pulsed width of 2.3 μ*** highest pulse energy exhibited by the generated pulse is 18.8 nJ with a signal to noise ratio of ~40 *** tunability of the proposed laser covers from 1042 to 1082 nm,giving a tuning range of 40 nm.

关键词： Tunable passively Q-switched ytterbium-doped fiber laser with mechanically exfoliated GaSe saturable absorber SA

Effects of Main-chain and Chain-ends on the Organogelation of Stearoyl Appended Pendant Valine Based Polymers

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Chinese Journal of Polymer Science 2019年第9期37卷 903-911页

作者： Mridula Nandi Swagata Pan Dipannita Ghosh Priyadarsi De Polymer research centre and centre for Advanced Functional Materials Department of Chemical Sciences Indian Institute of Science Education and Research Kolkata

In this work, we investigated the effect of hydrophobic interactions between the polymeric backbone and chain-end groups on the self-assembly pathway of stearoyl appended side-chain valine（Val）-based poly（methacrylate/acrylate） homopolymers in different organic hydrocarbons. Gelation studies conducted revealed that while polymers with polyacrylate as backbone induces gelation in several organic hydrocarbons, polymers with polymethacrylate in the main-chain significantly hinders macroscopic gelation. Morphology of the organogels was analysed by field emission scanning electron microscopy（FESEM）, and mechanical strengths of the organogels were determined by rheological measurements. Reversible addition-fragmentation chain transfer（RAFT） polymerization chain transfer agents（CTA）s, [R1―S―C=（S）―S―R2] with different ―R1 and ―R2 groups, have been employed to study the effect of structural variation at the chain-end on macroscopic assembly mechanism. We found that the additional interactions between terminal groups via hydrogenbonding or π-π stacking interactions or both help to build up the self-assembly pathway and thereby produces mechanically stable organogels.

关键词： Organogelation Hydrophobic interactions Poly(methacrylate/acrylate) backbone RAFT polymerization Self-assembly

Current efficiency in electro-winning of lanthanum and cerium metals from molten chloride electrolytes

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Rare Metals 2013年第3期32卷 305-311页

作者： Deepak Kumar Sahoo Harvinderpal Singh Nagaiyar Krishnamurthy Rare Earths Development Section Bhabha Atomic Research Centre Fusion Reactor Materials Section Bhabha Atomic Research Centre

The objective of this study is to prepare lan- thanum and cerium metals by fused salt electrolysis of their anhydrous chloride in molten media such as LiCl-KCl, NaCl-KCl, KCl, NaCl, and LiCl and to characterize the metal deposit by X-ray diffraction, energy dispersive X-ray fluorescence, and inductive coupled plasma-atomic emis- sion spectroscopy. Deposit metal of purity more than 99 % was obtained in each of the experiments. The entire process starting from preparation of anhydrous lanthanum/cerium chloride to electrolysis yielding of metal deposits has been described. The effect of process parameters such as tem- perature, electrolyte composition, and current density on the current efficiency was studied. All these parameters were varied to get the highest current efficiency and metal yield. The major non-rare earth impurities with the deposit are found to be Fe, Cr, and Ni along with - 1× 10^-3 of total gaseous impurities.

关键词： Fused salt electrolysis Current density Current efficiency Rare earths

Wavy properties and analytical modeling of free-surface flows in the development of the multi-domain method

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Journal of Hydrodynamics 2016年第6期28卷 971-976页

作者： Xiaobo CHEN Hui LIANG Deepwater Technology research centre Bureau Veritas

The wavy （oscillatory both in space and in time） properties of free-surface flows due to presence of floating bodies are analyzed within the framework of the potential-flow theory by assuming that the fluid is perfect and flow irrotational. A so-called new multi-domain method has been developed based on the fluid domain division by an analytical control surface surrounding bodies and the application of different methods adapted in the external and internal domains. In the analytical domain external to the control surface, the fundamental solution satisfying the linear boundary condition on the free surface associated with a point singularity （often called Green fimction and referred here as point solution） is applied to capture all wavy features of free-surface flows extending horizontally to infinity. Unlike classical studies in which the control surface is discretized, the unknown velocity potential and its normal derivatives are expressed by expansions of orthogonal elementary functions. The velocity potential associa- ted with each elementary distribution （elementary solutions） on the control surface can be obtained by performing multi-fold inte- grals in an analytical way. In the domain internal to the control surface containing the bodies, we could apply different methods like the Rankine source method based on the boundary integral equations for which the elementary solutions obtained in the external domain playing the role of Dirichlet-to-Neumarm operator close the problem.

关键词： analytical modeling multi-domain method point solution (PS) elementary solution (ES) body solution (BS)

Robot Pheromone Communication Using Vortex Ring Transmission

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Journal of Bionic Engineering 2009年第2期6卷 153-160页

作者： R.Andrew Russell Intelligent Robotics research centre Monash University

Unpredictable air movements have proved to be a problem in previous studies investigating robot communication by means of airborne pheromone chemicals. The project described in this paper investigates the use of air vortex rings as a means of carrying pheromone chemicals between transmitting and receiving robots. Sensitivity to chemicals including pheromones released by conspecifics is essential for many aspects of an insect's life. They assist in finding food, locating a mate, avoiding danger and help coordinate the activities of social insects. In the future, autonomous robots will be challenged by many situations similar to those that face insects and other simple creatures. Chemical communication may prove useful for these robots as well. This paper describes the equipment developed for generating and detecting vortex rings. Results of experiments involving location and tracking of a sequence of pheromone vortex rings are also presented.

关键词： chemical communication vortex transmission crickets biomimetic robots

Role of boron in TiAl alloy development: a review

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Rare Metals 2016年第1期35卷 1-14页

作者： Dawei Hu Interdisciplinary research centre in Materials University of Birmingham

Boron was found to be a unique grain refiner in cast TiAl alloys in the beginning of 1990 s and has become an element in most of the TiAl alloys developed to *** the past 25 or so years,efforts to understand the role of boron in solidification,solid-phase transformation,thermal and thermomechanical processing and mechanical properties of TiAl alloys and the relevant mechanisms never *** a result,abundant knowledge on boron in TiAl alloys has been accumulated but scattered in various research papers and conference *** review summarises the progress in understanding boron and its impacts on the TiAl alloy systems.

关键词： Titanium aluminide TiAl Ti3Al Boron Grain refinement

Electrochemical behavior of cerium(Ⅳ) in a RTIL and its mixture with ethanol

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Journal of Rare Earths 2014年第7期32卷 641-647页

作者： Arijit Sengupta M.S.Murali P.K.Mohapatra Radiochemistry Division Bhabha Atomic Research Centre

A systematic study was carried out to explore the electrochemical behavior of Ce in room temperature ionic liquid（CnmimBr, where n=6, 8, 10） and mixture of C6 mimBr and ethanol by cyclic voltammetry. With increase in the number of carbon atoms on the alkyl substituent on methyl imidazolium cation, the electrochemical window of the ionic liquids was found to extend towards more negative potential value, as a result there was a possibility of reduction of Ce to lower oxidation states. The diffusion coefficient and activation energy for the diffusion were calculated in all the ionic liquids and one of their mixtures with ethanol. With increase in n value, the diffusion coefficient of Ce decreased due to increase in viscosity of the medium while the activation energy for the diffusion followed a reverse trend for C6 mimBr, C8 mimBr and C10 mimBr, respectively. The observations indicated that the nature of species of Ce might be different in room temperature ionic liquids（RTILs） from that present in their mixtures with ethanol.

关键词： cerium cyclic voltammetry diffusion coefficient activation energy ethanol Cn mimBr (n=6, 8, 10) rare earths

Effects of Sr^(2+) substitution on the structural, dielectric, and piezoelectric properties of PZT-PMN ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 175-180页

作者： Arvind Kumar S.K. Mishra research and Technology Development centre Sharda University

This study described the structural, dielectric, and piezoelectric behavior of Pb1-xSrx[（Zr0.52Ti0.48）0.95（Mn1/3Nb2/3）0.05]O3 ceramics （PSZT-PMN, x=0, 0.025, 0.050, and 0.075）, prepared by a semi-wet route. X-ray diffraction, dielectric, and piezoelectric investigations were carried out to analyze the crystal structure. The relative dielectric constant and dielectric loss were both calculated as the functions of temperature. The room-temperature dielectric constant reaches a maximum for a Sr2＋-modified PZT-PMN ceramic with an x value of 0.050, which corresponds to the morphotropic phase boundary （MPB）. Raman spectroscopy studies also confirm the existence of this MPB for x=0.050. The piezoelectric strain coefficients （d33） value shows a maximum response for this composition. In addition, the phase transition temperature decreases significantly when the Sr2＋concentration increases in the PZT-PMN ceramics.

关键词： ceramic materials strontium substitution structural properties dielectric properties piezoelectricity

Impact of ocean data assimilation on the seasonal forecast of the 2014/15 marine heatwave in the Northeast Pacific Ocean

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 24-31页

作者： Tiantian Tang Jiaying He Huihang Sun Jingjia Luo Institute for Climate and Application research(ICAR)/Key Laboratory of Meteorological Disaster Nanjing University of Information Science and TechnologyNanjingChina

A remarkable marine heatwave,known as the“Blob”,occurred in the Northeast Pacific Ocean from late 2013 to early 2016,which displayed strong warm anomalies extending from the surface to a depth of 300 *** study employed two assimilation schemes based on the global Climate Forecast System of Nanjing University of Information Science(NUIST-CFS 1.0)to investigate the impact of ocean data assimilation on the seasonal prediction of this extreme marine *** sea surface temperature(SST)nudging scheme assimilates SST only,while the deterministic ensemble Kalman filter(EnKF)scheme assimilates observations from the surface to the deep *** latter notably improves the forecasting skill for subsurface temperature anomalies,especially at the depth of 100-300 m(the lower layer),outperforming the SST nudging *** excels in predicting both horizontal and vertical heat transport in the lower layer,contributing to improved forecasts of the lower-layer warming during the *** improvements stem from the assimilation of subsurface observational data,which are important in predicting the upper-ocean *** results suggest that assimilating ocean data with the EnKF scheme significantly enhances the accuracy in predicting subsurface temperature anomalies during the Blob and offers better understanding of its underlying mechanisms.

关键词： Seasonal forecast Ocean data assimilation Marine heatwave Subsurface temperature