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Mode-locked 2 μm fiber laser with a multi-walled carbon nanotube as a saturable absorber

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Chinese Optics Letters 2015年第3期13卷 10-13页

作者： S.M.Azooz F.Ahmad H.Ahmad S.W.Harun B.A.Hamida S.Khan a.halder M.C.Paul M.Pal S.K.Bhadra Department of Electrical Engineering Faculty of Engineering University of Malaya Photonics Research Center University of Malaya Department of Electrical and Computer Engineering International Islamic University MalaysiaJalan Gombak Fiber Optics and Photonics Division Central Glass & Ceramic Research InstituteCSIR

We propose and demonstrate a passively mode-locked fiber laser operating at 1951.8 nm using a commercial thulium-doped fiber （TDF） laser, a homemade double-clad thulium-ytterbium co-doped fiber （TYDF） as the gain media, and a multi-walled carbon nanotube （MWCNT） based saturable absorber （SA）. We prepare the MWCNT composite by mixing a homogeneous solution of MWCNTs with a diluted polyvinyl alcohol （PVA） polymer solution and then drying it at room temperature to form a film. The film is placed between two fiber connectors as a SA before it is integrated into a laser ring cavity. The cavity consists of a 2 m long TDF pumped by a 800 nm laser diode and a 15 m long homemade TYDF pumped by a 905 nm multimode laser diode. A stable mode-locking pulse with a repetition rate of 34.6 MHz and a pulse width of 10.79 ps is obtained when the 905 nm multimode pump power reaches 1.8-2.2 W, while the single-mode 800 nm pump power is fixed at 141.5 mW at all times. To the best of our knowledge, this is the first reported mode-locked fiber laser using a MWCNT-based SA.

关键词： MWCNTs mode Mode-locked 2 m fiber laser with a multi-walled carbon nanotube as a saturable absorber

Self-starting harmonic mode-locked Tm-Bi co-doped germanate f iber laser with carbon nanotube-based saturable absorber

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Chinese Optics Letters 2013年第6期11卷 81-83页

作者： N.Saidin D.I.M.Zen S.S.A.Damanhuri S.W.Harun H.Ahmad F.Ahmad K.Dimyati a.halder M.C.Paul M.Pal S.K.Bhadra Photonics Research Centre University of Malaya50603 Kuala LumpurMalaysia Department of Electrical Engineering Faculty of EngineeringUniversity of Malaya50603 Kuala LumpurMalaysia Department of Electrical and Electronic Engineering National Defense University of MalaysiaKem Sungai Besi57000 Kuala LumpurMalaysia Fiber Optics and Photonics Division Central Glass and Ceramic Research InstituteCSIRKolkataIndia

We report a ring cavity passively harmonic mode-locked fiber laser using a newly developed thulium- bismuth co-doped fiber （TBF） as a gain medium in conjunction with a carbon nanotube （CNT）-based saturable absorber. The TBF laser generates a third harmonic mode-locked soliton pulse train with a high repetition rate of 50 MHz and a pulse duration of 1.86 ps. The laser operates at 1 901.6 nm with an average power of 6.6 mW, corresponding to a pulse energy of 0.132 nJ, at a 1 552 nm pump power of 723.3 roW.

关键词： mode Self-starting harmonic mode-locked Tm-Bi co-doped germanate f iber laser with carbon nanotube-based saturable absorber CNT Tm Bi

Heat Transfer and Thermal Characteristics Effects on Moving Plate Impinging from Cu-Water Nanofluid Jet

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Journal of Thermal Science 2020年第1期29卷 182-193页

作者： DATTA Abanti KUMAR Sonal halder Pabitra Department of Aerospace Engineering and Applied Mechanics Indian Institute of Engineering Science and Technology

The present article is focused on modelling of flow and heat transfer behaviour of Cu-water nanofluid in a confined slot jet impingement on hot moving *** parameters such as various moving plate velocities,nanoparticles at various concentrations,variation in turbulent Reynolds number and jet nozzle to plate distance have been considered to study the flow field and convective heat transfer performance of the *** of distribution of local and average Nusselt number and skin friction coefficients at the plate surface are shown to elucidate the heat transfer and fluid flow *** analysis of both stream function and isotherm contours are carried out to perceive the flow pattern and heat transfer mechanism due to moving *** results revealed that average Nusselt number significantly rises with plate velocity in addition with jet inlet Reynolds *** of the average Nusselt numbers are presented.

关键词： Cu-water nanofluid,multiphase mixture model moving plate jet impingement CFD

Nonequilibrium Phase Transition in Spin-S Ising Ferromagnet Driven by Propagating and Standing Magnetic Field Wave

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Communications in Theoretical Physics 2017年第11期67卷 600-610页

作者： Ajay halder Muktish Acharyya Department of Physics Presidency University

The dynamical response of spin-S(S=1, 3/2, 2, 3) Ising ferromagnet to the plane propagating wave, standing magnetic field wave and uniformly oscillating field with constant frequency are studied separately in two dimensions by extensive Monte Carlo simulation. Depending upon the strength of the magnetic field and the value of the spin state of the Ising spin lattice two different dynamical phases are observed. For a fixed value of S and the amplitude of the propagating magnetic field wave the system undergoes a dynamical phase transition from propagating phase to pinned phase as the temperature of the system is cooled down. Similarly in case with standing magnetic wave the system undergoes dynamical phase transition from high temperature phase where spins oscillate coherently in alternate bands of half wavelength of the standing magnetic wave to the low temperature pinned or spin frozen phase. For a fixed value of the amplitude of magnetic field oscillation the transition temperature is observed to decrease to a limiting value as the value of spin S is increased. The time averaged magnetisation over a full cycle of the magnetic field oscillation plays the role of the dynamic order parameter. A comprehensive phase boundary is drawn in the plane of magnetic field amplitude and dynamic transition temperature. It is found that the phase boundary shrinks inwards for high value of spin state *** in the low temperature(and high field) region the phase boundaries are closely spaced.

关键词： Ising model dynamic phase transition Monte-Carlo algorithm propagating wave standing wave

Robust Nonlinear Analytic Redundancy for Fault Detection and Isolation in Mobile Robot

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International Journal of Automation and computing 2007年第2期4卷 177-182页

作者： Bibhrajit halder Nilanjan Sarkar Department of Mechanical Engineering Vanderbilt UniversityNashvilleTN-37212USA

A robust nonlinear analytical redundancy （RNLAR） technique is presented to detect and isolate actuator and sensor faults in a mobile robot. Both model-plant-mismatch （MPM） and process disturbance are considered during fault detection. The RNLAR is used to design primary residual vectors （PRV）, which are highly sensitive to the faults and less sensitive to MPM and process disturbance, for sensor and actuator fault detection. The PRVs are then transformed into a set of structured residual vectors （SRV） for fault isolation. Experimental results on a Pioneer 3-DX mobile robot are presented to justify the effectiveness of the RNLAR scheme.

关键词： Fault detection fault isolation nonlinear systems robustness uncertainty.

Rhyolites in continental mafic Large Igneous Provinces: Petrology,geochemistry and petrogenesis

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Geoscience Frontiers 2021年第1期12卷 53-80页

作者： Mahesh halder Debajyoti Paul Sarajit Sensarma Department of Earth Sciences Indian Institute of Technology KanpurKanpur 208016India Centre of Advanced Study in Geology University of LucknowLucknow 226007India

We present a detailed review of the petrological and geochemical aspects of rhyolite and associated silicic volcanic rocks(up to 20 vol%of all rocks)reported to date from twelve well known Phanerozoic continental mafic Large Igneous Provinces(LIPs).These typically spread over900℃.Rhyolites formed by significant crustal contribution are characterized by strong negative Nb-Ta anomalies,absence of clinopyroxene phenocrysts,and are likely to have a magma temperature<900℃.Geochemical signatures suggest rhyolite melt generation in the plagioclase stability field with a minor fraction originating from lower crustal depths.A large part of the compositional variability in rhyolites,particularly the SrNd-Pb-O isotope ratios,suggests a significant role of continental crust(upper crustal melting or AFC)in the evolution of these silicic rocks in the continental mafic LIPs.

关键词： Large Igneous Province Silicic rock Rhyolite Geochemistry Petrogenesis AFC

Strategies for translating proteomics discoveries into drug discovery for dementia

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Neural Regeneration Research 2024年第1期19卷 132-139页

作者： Aditi halder Eleanor Drummond School of Medical Sciences and Brain&Mind Center University of SydneyNSWSydneyAustralia Department of Aged Care Prince of Wales HospitalSydneyNSWAustralia

Tauopathies,diseases characterized by neuropathological aggregates of tau including Alzheimer's disease and subtypes of fro ntotemporal dementia,make up the vast majority of dementia *** there have been recent developments in tauopathy biomarkers and disease-modifying treatments,ongoing progress is required to ensure these are effective,economical,and accessible for the globally ageing *** such,continued identification of new potential drug targets and biomarkers is critical."Big data"studies,such as proteomics,can generate information on thousands of possible new targets for dementia diagnostics and therapeutics,but currently remain underutilized due to the lack of a clear process by which targets are selected for future drug *** this review,we discuss current tauopathy biomarkers and therapeutics,and highlight areas in need of improvement,particularly when addressing the needs of frail,comorbid and cognitively impaired *** highlight biomarkers which have been developed from proteomic data,and outline possible future directions in this *** propose new criteria by which potential targets in proteomics studies can be objectively ranked as favorable for drug development,and demonstrate its application to our group's recent tau interactome dataset as an example.

关键词： Alzheimer's disease biomarkers drug development drug discovery druggability frontotemporal dementia interactome proteomics tau tauopathies therapeutics

Development of a mass model in estimating weight-wise particle size distribution using digital image processing

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International Journal of Mining Science and Technology 2017年第3期27卷 435-443页

作者： Maiti Abhik Chakravarty Debashish Biswas Kousik halder Arpan Department of Mining Engineering Indian Institute of Technology Kharag-pur 721302 India

Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast and accurate, is often expressed in terms of area function or number of particles. In this paper, a mass model is developed which converts the image obtained size distribution to mass-wise distribution, mak- ing it readily comparable to mechanical sieving data. The concept of weight/particle ratio is introduced for mass reconstruction from 2D images of particle aggregates. Using this mass model, the effects of several particle shape parameters （such as major axis, minor axis, and equivalent diameter） on sieve-size of the particles is studied. It is shown that the sieve-size of a particle strongly depend upon the shape param- eters, 91% of its variation being explained by major axis, minor axis, bounding box length and equivalent diameter. Furthermore, minor axis gives an overall accurate estimate of particle sieve-size, error in mean size （D-50） being just 0.4%. However, sieve-size of smaller particles （〈20 ram） strongly depends upon the length of the smaller arm of the bounding box enclosing them and sieve-sizes of larger particles （〉20 mm） are highly correlated to their equivalent diameters. Multiple linear regression analysis has been used to generate overall mass-wise particle size distribution, considering the influences of all these shape parameters on particle sieve-size. Multiple linear regression generated overall mass-wise particle size distribution shows a strong correlation with sieve generated data. The adjusted R-square value of the regression analysis is found to be 99 percent （w.r,t cumulative frequency）. The method proposed in this paper provides a time-efficient way of producing accurate （up to 99%） mass-wise PSD using digital image processing and it can be used effectively to renlace the mechanical sieving.

关键词： Particle size distribution Image analysis Particle shape parameters Weight/particle ratio Sieve analysis

The importance of laminin at the blood-brain barrier

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Neural Regeneration Research 2023年第12期18卷 2557-2563页

作者： Sebok K.halder Arjun Sapkota Richard Milner San Diego Biomedical Research Institute San DiegoCAUSA

The blood-brain barrier is a unique property of central nervous system blood vessels that protects sensitive central nervous system cells from potentially harmful blood *** mechanistic basis of this barrier is found at multiple levels,including the adherens and tight junction proteins that tightly bind adjacent endothelial cells and the influence of neighboring pericytes,microglia,and astrocyte *** addition,extracellular matrix components of the vascular basement membrane play a critical role in establishing and maintaining blood-brain barrier integrity,not only by providing an adhesive substrate for blood-brain barrier cells to adhere to,but also by providing guidance cues that strongly influence vascular cell *** extracellular matrix protein laminin is one of the most abundant components of the basement membrane,and several lines of evidence suggest that it plays a key role in directing blood-brain barrier *** this review,we describe the basic structure of laminin and its receptors,the expression patterns of these molecules in central nervous system blood vessels and how they are altered in disease states,and most importantly,how genetic deletion of different laminin isoforms or their receptors reveals the contribution of these molecules to blood-brain barrier function and ***,we discuss some of the important unanswered questions in the field and provide a“to-do”list of some of the critical outstanding experiments.

关键词： astrocytes basement membrane blood vessels blood-brain barrier integrity dystroglycan endothelial cells inflammation integrins laminin pericytes