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STEADY-SHEAR VISCOSITY AND TRANSIENT STRESS RESPONSE FOR ELASTO-THIXOTROPIC FLUIDS

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Acta mechanica Sinica 1991年第1期7卷 46-50页

作者： Fang Tunan (1) Carlos tiu (2) 1. Deparment of Chemical Engineering East China University of Chemical Technology Shanghai China 2. Department of Chemical Engineering Monash University 3168 Clayton Victoria Australia

A phenomenological model for dispersed systems which exhibit complex theological behaviour such as shear and time-dependent viscosity, yield stress, and elasticity is proposed. The model extends the Quemeda model to describe the viscosity function with a structural parameter λ which varies according to differ- ent kinetic orders of particle aggregation and segregation. The transient stress response is obtained by solving an instantaneous maxwell model with an assumed shear modulus function G of the same form as the viscosity function η. Accuracy of the proposed model is verified experimentally with the results obtained for two oil (creosote)/water emulsions. The model that gives the best fit of experimental data appears to be the one with kinetic orders n = m = 2.

关键词： elasto-thixotropic fluid Theological model steady-shear viscosity transient stress response

Nonlinear Polarization Rotation-Based mode-Locked Erbium-Doped Fiber Laser with Three Switchable Operation States

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Chinese Physics Letters 2014年第9期31卷 76-78页

作者： Zian Cheak tiu Sin Jin Tan Arman Zarei Harith Ahmad Sulaiman Wadi Harun Department of Electrical Engineering Faculty of Engineering University of Malaya Kuala Lumpur 0603 Malaysia Photonics Research Center University of Malaya Kuala Lumpur 50603 Malaysia School of Engineering KDu University Collegel Petaling Jaya 47400 Malaysia

A simple mode-locked erbium-doped fiber laser （EDFL） with three switchable operation states is proposed and demonstrated based on nonlinear polarization rotation. The EDFL generates a stable square pulse at a third harmonic pulse repetition rate of 87kHz as the 1480 nm pump power increases from the threshold of 17.5 m W to 34.3mW. The square pulse duration increases from 105 ns to 245ns as the pump power increases within this region. The pulse operation switches to the second operation state as the pump power is varied from 48.2mW to *** W. The laser operates at a fundamental repetition rate of 29 kHz with a fixed pulse width of 8.5 μs within the pump power region. At a pump power of ***, the average output power is 3.84mW, which corresponds to the pulse energy of 131.5 ng. When the pump power continues to increase, the pulse train experiences unstable oscillation before it reaches the third stable operation state within a pump power region of 138.9 m W to 145.0 m W. Within this region, the EDFL produces a fixed pulse width of 2.8 μs and a harmonic pulse repetition rate of 58 kHz.

关键词： NONLINEAR theories RESEARCH POLARIZATION (Nuclear physics) FIBER lasers HARmONICS (Electric waves) ERBIUm

Size hierarchy of gold clusters in nanogold-catalyzed acetylene hydrochlorination

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Nano Research 2024年第11期17卷 9594-9600页

作者： Yifei Zhang Xinrui Gu Fatimah Kehinde busari Sami Barkaoui Zhong-Kang Han Alfons Baiker Zhen Zhao Gao Li Institute of Catalysis for Energy and Environment College of Chemistry and Chemical Engineering Shenyang Normal University Shenyang 110034 China State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China School of materials Science and Engineering Zhejiang University Hangzhou 310000 China Department of Chemistry and Applied Biosciences ETH Hönggerberg HCI CH-8093 Zurich Switzerland University of Chinese Academy of Sciences Beijing 100049 China

Size hierarchy is a distinct feature of nanogold-catalysts as it can strongly affect their performance in various reactions. We developed a simple method to generate Au n S m nanoclusters of different sizes by thermal treatment of an Au144(PET)60 (PET: phenylethanethiol) parent cluster. These clusters, deposited on activated carbon, exhibit excellent catalytic performance in the hydrochlorination of acetylene. In-situ ultraviolet laser dissociation high-resolution mass spectrometry of the parent cluster in the presence of acetylene revealed a remarkable cluster size-dependence of acetylene adsorption, which is a crucial step in the hydrochlorination. Systematic density functional theory calculations of the reaction pathways on the differently-sized clusters provide deeper insight into the cluster size dependence of the adsorption energies of the reactants and afforded a scaling relationship between the adsorption energy of acetylene and the co-adsorption energies of the reactants (C_(2)H_(2) and HCl), which could enable a qualitative prediction of the optimal Au n S m cluster for the hydrochlorination of acetylene.

关键词： gold clusters size hierarchy AunSm acetylene hydrochlorination scaling relationship

Sustainability issues on rice–wheat cropping system

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International Soil and Water Conservation Research 2016年第1期4卷 64-74页

作者： Rajan Bhatt Surinder S Kukal m.tiu a busari Sanjay Arora mathura Yadav Farm Advisory Service Scheme Tarn TaranPunjab Agricultural UniversityLudhiana-141004PunjabIndia b Department of Soil Science Punjab Agricultural University141004 LudhianaPunjabIndia Central Soil Salinity Research Institute(ICAR) RRSLucknowUttar PradeshIndia Department of Soil Science and Land management Federal University of AgricultureP.M.B.2240 AbeokutaNigeria National Wheat Research Program BhairahawaRupandehiNepal

Rice–wheat cropping system(RWCS)of the South Asia is labour-,water-,capital-and energy-intensive,and become less profitable as the availability of these resources *** could be further aggravated with deterioration of soil structure,declining underground water and lesser land and water productivity which ultimately are threat in front of sustainable and profitable RWCS in the *** improving the profits,production and sustainability of this sequence-a paradigm shift is *** recommended different resource-conserving technologies(RCTs)*** tillage,laser levelling,irrigation based on soil matric potential,bed planting,direct seeding,mechanical transplanting of rice and crop diversification for this *** technologies are site specific and before selecting any particular RCT for a particular region,soil texture and agro-climatic conditions must be considered.A solitary approach/RCT might not be effective to solve the upcoming issue of producing more food grains with inadequate available water and ***,an integrated approach is *** before implementing any approach,different issues relating to RWCS must be discovered,considered and addressed in a holistic *** this review,an attempt was made to highlight different issues resulted from the practise of intensive rice–wheat cropping sequence of the region,which must be considered while framing and implementing any integrated approach/project such as conservation agriculture for improving the productions,profits and sustainability of RWCS in the region.

关键词： Rice Wheat Sustainability issues Climate smart agriculture

Conservation tillage impacts on soil,crop and the environment

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International Soil and Water Conservation Research 2015年第2期3卷 119-129页

作者： m.tiu Abolanle busari Surinder Singh Kukal Amanpreet Kaur Rajan Bhatt Ashura Ally Dulazi Department of Soil Science and Land management Federal University of AgricultureP.M.B.2240 AbeokutaNigeria Department of Soil Science Punjab Agricultural university141001 LudhianaIndia ministry of Agriculture Food Security and CooperativesAgriculture Research InstituteMakutuporaDodomaP.O.BOX 1676Tanzania

There is an urgent need to match food production with increasing world population through identification of sustainable land management ***,the struggle to achieve food security should be carried out keeping in mind the soil where the crops are grown and the environment in which the living things *** agriculture(CA),practising agriculture in such a way so as to cause minimum damage to the environment,is being advocated at a large scale *** tillage,the most important aspect of CA,is thought to take care of the soil health,plant growth and the *** paper aims to review the work done on conservation tillage in different agro-ecological regions so as to understand its impact from the perspectives of the soil,the crop and the *** reports have identified several benefits of conservation tillage over conventional tillage(CT)with respect to soil physical,chemical and biological properties as well as crop *** less than 25%of the greenhouse gas effluxes to the atmosphere are attributed to *** of climate change mitigation and adaptation found zero tillage(ZT)to be the most environmental friendly among different tillage ***,conservation tillage involving ZT and minimum tillage which has potential to break the surface compact zone in soil with reduced soil disturbance offers to lead to a better soil environment and crop yield with minimal impact on the environment.&2015 International Research and Training Center on Erosion and Sedimentation and China Water and Power *** and Hosting by Elsevier *** is an open access article under the CC BY-NC-ND license(http://***/licenses/by-nc-nd/4.0/).

关键词： Atmosphere Greenhouse gases Conservation tillage Sustainable crop yield

A numerical simulation of the influence initial temperature has on the propagation characteristics of, and safe distance from, a gas explosion

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International Journal of mining Science and Technology 2012年第3期22卷 307-310页

作者： Jiang Bingyou Lin Baiquan Shi Shulei Zhu Chuanjie tiu Qian Zhai Cheng Faculty of Safety Engineering China University of Mining & Technology Xuzhou 221116 China State Key Laboratory of Coal Resources and mine Safety China University of Mining & Technology Xuzhou 221008 China School of management Jiangsu Normal University Xuzhou 221009 China

A model roadway with a cross-sectional area of 80 mm 80 mm and a length of 100 m was used to estimate the overpressure, the temperature, the density, and the combustion rate during an explosion. Auto-ReaGas software was used for the calculations and the initial temperatures were 248, 268, 308, or 328 K. The methaneair mixture had a fuel concentration of 9.5% and the tunnel had a filling ratio of 10%. The results show that the safe distance necessary to avoid harm from the shock wave increases with increasing initial temperature. The distance where the peak overpressure begins to rise, and where the maximum value occurs, increases as the initial temperature increases. These are almost linear functions of the initial temperature. At locations before shock wave attenuation has occurred increasing the initial temperature linearly increases the maximum temperature at each point following along the tunnel. At the same time, the peak overpressure, the maximum density, and the maximum combustion rate decrease linearly. How-ever, after the shock wave has attenuated the attenuation extent of the peak overpressure decreases with an increase in initial temperature. The influence of the initial temperature on the explosion propagation depends on the combined effects of inhibiting and enhancing factors. The research results can provide a theoretical guidance for gas explosion disaster relief and treatment in underground coal mines.

关键词： Initial temperatureGas explosionShock waveSafety distanceNumerical simulation

Dark pulse emission in nonlinear polarization rotation-based multiwavelength mode-locked erbium-doped fiber laser

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Chinese Optics Letters 2014年第11期12卷 119-121页

作者： Zian Cheak tiu Sin Jin Tan Harith Ahmad Sulaiman Wadi Harun Department of Electrical Engineering Faculty of EngineeringUniversity of Malaya50603 Kuala Lumpur Malaysia Photonics Research Center University of Malaya50603 Kuala Lumpur Malaysia School of Engineering KDU University College SS22/41 Damansara Jaya 47400 Petaling JayaSelangor Darul Ehsan Malaysia

We experimentally show dark pulse generation in all-normal dispersion multiwavelength erbium-doped fiber laser（EDFL） with a long cavity of figure-of-eight configuration. The EDFL generates a stable multiwavelength laser with 0.47 nm spacing at 24 m W threshold pump power, while the number of lines obtained increases with the pump power. A dark pulse emission is observed as the pump power is increased above 137 m W, with fundamental repetition rate of 29 k Hz and pulse width of 2.7 μs. It is observed that the dark pulse train can be shifted to second-, third-, and fourth-order harmonic dark pulses by carefully adjusting the polarization controller. For the fundamental dark pulse, the maximum pulse energy of 32.4 n J is obtained at pump power of 146.0 mW.

关键词： mode length Dark pulse emission in nonlinear polarization rotation-based multiwavelength mode-locked erbium-doped fiber laser

All-fiber, wavelength-tunable ultrafast praseodymium fiber laser

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Chinese Optics Letters 2018年第12期16卷 56-60页

作者： H.Ahmad S.N.Aidit S.I.Ooi Z.C.tiu Photonics Research Centre University of Malaya Department of Physics Faculty of Science and TechnologyAirlangga University

The interest in tunable ultrafast fiber lasers operating in the 1.3 μm region has seen a significant increase due to rising demands for bandwidth as well as the zero-dispersion characteristic of silica fibers in this wavelength region. In this work, a tunable mode-locked praseodymium-doped fluoride fiber(PDFF) laser using single-walled carbon nanotubes as a saturable absorber is demonstrated. The mode-locked pulses are generated at a central wavelength of 1302 nm with a pulse repetition rate of 5.92 mHz and pulse width of 1.13 ps. The tunability of the mode-locked PDFF laser covers a tuning range of 11 nm.

关键词： All-fiber wavelength-tunable ultrafast praseodymium fiber laser SWCNTs

Generation of passively Q-switched fiber laser at 1 μm by using moSSe as a saturable absorber

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Chinese Optics Letters 2017年第2期15卷 15-19页

作者： H. Ahmad S. A. Reduan S. N. Aidit Z. C. tiu Photonics Research Centre University of Malaya Kuala Lumpur 50603 Malaysia

Passively Q-switched ytterbium-doped fiber lasers （YDFLs） incorporating a molybdenum sulfide selenide （moSSe）-based saturable absorber （SA） are demonstrated. The modulation depth and saturation intensity of the moSSe-based SA are measured to be approximately 25.0% and 0.002 mW/cm^2, respectively, using the twin detector technique. The YDFL＇s output has a center wavelength of 1038.5 nm with a top pulse width and energy of 1.2 μs and 18.9 nJ, respectively, at a pump power of 333 mW. The moSSe-based SA has a good linear optical response, providing significant opportunity for use in applications over an ultra-broadband spectrum, particularly spectroscopy and biomedical diagnostics.

关键词： mo Generation of passively Q-switched fiber laser at 1 m by using mo SSe as a saturable absorber SA