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A MATHEMATICAL THEORY FOR LEs CONVERGENCE

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Acta Mathematica scientia 2012年第1期32卷 237-258页

作者： H.Lim T.Kaman V.Mahadeo J.Glimm s.dutta D.H.sharp B.Plohr Department of Applied Mathematics and statistics Stony Brook University College of st.Catherine Los Alamos National Laboratory

Practical simulations of turbulent processes are generally cutoff, with a grid resolution that stops within the inertial range, meaning that multiple active regions and length scales occur below the grid level and are not resolved. This is the regime of large eddy simulations （LEs）, in which the larger but not the smaller of the turbulent length scales are resolved. solutions of the fluid Navier-stokes equations, when considered in the inertial regime, are conventionally regarded as solutions of the Euler equations. In other words, the viscous and diffusive transport terms in the Navier-stokes equations can be neglected in the inertial regime and in LEs simulations, while the Euler equation becomes fundamental. For such simulations, significant new solution details emerge as the grid is refined. It follows that conventional notions of grid convergence are at risk of failure, and that a new, and weaker notion of convergence may be appropriate. It is generally understood that the LEs or inertial regime is inherently fluctuating and its description must be statistical in nature. Here we develop such a point of view systematically, based on Young measures, which are measures depending on or indexed by space time points. In the Young measure du（ξ）x,t, the random variable ξ of the measure is a solution state variable, i.e., a solution dependent variable, representing momentum, density, energy and species concentrations, while the space time coordinates, x, t, serve to index the *** evidence suggests that convergence via Young measures is suifficiently weak to encompass the LEs/inertial regime; numerical and theoretical evidence suggests that this notion may be required for passive scalar concentration and therm degrees of freedom. Our objective in this research is twofold： turbulent simulations without recourse to ad- justable parameters （calibration） and extension to more complex physics, without use of additional models or parameters, in both cases with

关键词： numerical methods turbuent mixing

不同来源的芦荟对酪氨酸酶的抑制作用(英文)

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中国天然药物 2013年第6期11卷 616-620页

作者： s.dutta Gupta s.K.Masakapalli Department of Agricultural and Food Engineering Indian Institute of Technology Kharagpur Department of Plant sciences University of Oxford

In this study, lyophilized and methanolic extracts of aloe gel from different germplasms were evaluated for their potential to inhibit mushroom tyrosinase activity. The results showed potent inhibitory effect of Aloe vera gel extracts on L-dihydroxyphenylalanine(L-DOPA) oxidation catalyzed by tyrosinase in a dose-dependent manner. significant differences in % inhibition of tyrosinase among the extraction methods and the germplasms were observed. The relative performance of the germplasms was evaluated with the help of posthoc multicomparison test. The methanolic extract was more effective than the lyophilized crude gel in all the germplasms. The inhibitory effect of the lyophilized gel and methanolic extract tested from five germplasms followed the order: RM > TN > s24 > OR > RJN. The germplasm RM showed the highest tyrosinase inhibition, and the maximum % inhibition noted was 26.04% and 41.18%, respectively for the lyophilized and methanolic extracts at 6 mg·mL–1concentration. Lineweaver-Burk plots of the different concentrations of L-DOPA in the absence and presence of lyophilized gel extract showed competitive inhibition of mushroom tyrosinase in all the germplasms. This study suggests that the germplasm RM could potentially be used for the isolation and identification of the effective tyrosinase inhibitory component, and ascertains the critical role of selecting the best source of germplasm for natural product isolation and characterization.

关键词： Aloe vera L.gel Tyrosinase inhibitor L-DOPA Inhibition kinetics Germplasm sourcing

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钢芯铝线的新弛度-张力计算法

电力建设 1984年第9期 54-59页

作者： J.s.Barrett s.dutta O.Nigol 潘忠华安大略水电局研究部安大略水电局研究部安大略水电局研究部加拿大加拿大加拿大

序言一个新的弛度-张力计算机程序的产生,取决于改变架空线路运行条件以及设计工程师需要更加逼真的设计标准。改变运行条件的实际例子是运行温度的提高,以及架空导线因使用更为有效的振动控制措施而可提高导线张力。此外,现已有足够多... 详细信息

序言一个新的弛度-张力计算机程序的产生,取决于改变架空线路运行条件以及设计工程师需要更加逼真的设计标准。改变运行条件的实际例子是运行温度的提高,以及架空导线因使用更为有效的振动控制措施而可提高导线张力。此外,现已有足够多的蠕变数据可供在计算机程序中判断导线蠕变的

关键词：蠕变参数钢芯铝线应变曲线计算机程序线张力蠕变曲线导线长度弹性应变蠕变量方程式方程累加法弛度蠕变方程

structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)Bi_(0.5)TiO_(3) perovskite:Effect of ionic radius

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Journal of Rare Earths 2024年第2期42卷 383-391,I0006页

作者： Rajdip Roy Abhigyan dutta Department of Physics The University of BurdwanBurdwan713104India

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)B_(0.5)TiO_(3),NBT) based perovskite *** X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NBT nano perovskite incorporated with various rare earth ions in *** lattice parameters were found to increase linearly with the ionic radius of the dopant *** ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared *** grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic *** emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and *** UV-Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap,which unfolds the application of NBT-based perovskite as photoactive *** ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NBT compound,exhibits the highest dc and bulk conductivity with the lowest activation *** frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation *** also indicate that La-doped NBT composition exhibits the highest dielectric strength ***,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural,optical,and electrical properties.

关键词： Rare earth doped NBT Microstructural analysis Optical band gap AC Conductivity Dielectric relaxation Rare earths

Modelling rapid non-destructive test using light weight deflectometer on granular soils across different degrees of saturation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2732-2748页

作者： Javad Ghorbani Arooran sounthararajah Troyee Tanu dutta Jayantha Kodikara ARC smart Pavements Hub Dept.of Civil EngineeringMonash UniversityVIC3800Australia

This study introduces an advanced finite element model for the light weight deflectometer(LWD),which integrates contact mechanics with fully coupled *** simulating LWD tests on granular soils at various saturation levels,the model accurately reflects the dependence of the LWD modulus on dry density,water content,and effective *** model addresses and overcomes the limitations of previous finite element models for this specific ***,this research presents the first experimentally validated fully coupled contact impact ***,the research provides a comparative assessment of elastoplastic and nonlinear elastic models and contrasts an enriched node-tosegment method(developed in this study)with the more precise mortar technique for contact *** comparisons reveal unique advantages and challenges for each ***,the study underscores the importance of careful application of the LWD modulus,emphasising the need for sophisticated tools to interpret soil behaviour accurately.

关键词： Granular soils Plasticity Finite element analysis Contact mechanics Modulus Degree of saturation

Effect of process parameter on the flowability of nanocrystalline CoNiCrAlY powder synthesized by mechanical milling

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Particuology 2024年第9期92卷 210-223页

作者： Annadaa shankara Dash Indranil Manna Deepa Devapal sharad Chandra sharma Jyotsna dutta Majumdar school of Nanoscience and Technology IIT KharagpurWest BengalIndia BIT Mesra RanchiJharkhandIndia Department of Metallurgical and Materials Engineering IIT KharagpurWest BengalIndia Vikram sarabhai space Centre ThiruvanthapuramKeralaIndia

The present study concerns understanding the effect of process parameters on the characteristics and flowability of nanocrystalline CoNiCrAlY powder synthesized by mechanical *** milling has been conducted in a planetary ball mill with tungsten carbide(WC)ball,with ball to powder ratio of 10:1 at 300 rpm speed,using 1%stearic acid and toluene as process control agent(PCA)with time varying from 10 h to 36 *** synthesized nanocrystalline powder were characterized by scanning Electron Microscopy,X-ray Diffraction technique,X-ray Photoelectron spectroscopy,and Differential scanning ***,flowability in terms of Hausner ratio was assessed by Tap Density *** particle size of the powder was found to decrease from 33μm to 22μm after 10 h of milling and further increases to 43μm and 38μm after 25 and 36 h of milling,respectively,in stearic acid ***,in toluene medium particle size continuously decreases from 33μm to 9.7μm with increasing milling *** particle morphology changes from spherical to platelet shape at low milling hours in both of the *** 25 h of milling,the shape of the particles is nearly spherical for stearic acid and irregular for toluene used as a *** size was found to decrease with increasing milling time from 147 nm to 7.7 nm and to 6.4 nm in stearic acid and toluene media,*** was presence ofγ,γʹ,β,hcp-Co,Al_(2)O_(3)and AlOOH phases on the powder particles milled in both the *** measured Hausner ratio of the powders was found to vary from 1.18 to 1.32 in stearic acid medium,and was found to increase with increasing milling *** the other hand,in toluene media flowability decreases(Hausner ratio increases from 1.33 to 1.44)with increasing milling time.

关键词： Mechanical milling Microstructure Process control agent(PCA) CoNiCrAIY Toluene stearic acid Flowability

A framework for dynamic modelling of railway track switches considering the switch blades,actuators and control systems

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Railway Engineering science 2024年第2期32卷 162-176页

作者： saikat dutta Tim Harrison Christopher Ward Roger Dixon Phil Winship Institute of Thermofluids School of Mechanical EngineeringUniversity of LeedsLeedsWest YorkshireUK Wolfson school of Mechanical Electrical and Manufacturing EngineeringLoughborough UniversityLoughboroughLeicestershireUK Birmingham Centre for Railway Research and Education School of EngineeringUniversity of BirminghamBirminghamWest MidlandsUK Network Rail Milton KeynesBuckinghamshireUK

The main contribution of this paper is the development and demonstration of a novel methodology that can be followed to develop a simulation twin of a railway track switch system to test the functionality in a digital *** is important because,globally,railway track switches are used to allow trains to change routes;they are a key part of all railway ***,because track switches are single points of failure and safety-critical,their inability to operate correctly can cause significant delays and concomitant *** order to better understand the dynamic behaviour of switches during operation,this paper has developed a full simulation twin of a complete track switch *** approach fuses finite element for the rail bending and motion,with physics-based models of the electromechanical actuator system and the control ***,it provides researchers and engineers the opportunity to explore and understand the design space around the dynamic operation of new switches and switch machines before they are *** is useful for looking at the modification or monitoring of existing switches,and it becomes even more important when new switch concepts are being considered and *** simulation is capable of running in real time or faster meaning designs can be iterated and checked *** paper describes the modelling approach,demonstrates the methodology by developing the system model for a novel“REPOINT”switch system,and evaluates the system level performance against the dynamic performance requirements for the *** the context of that case study,it is found that the proposed new actuation system as designed can meet(and exceed)the system performance requirements,and that the fault tolerance built into the actuation ensures continued operation after a single actuator failure.

关键词： Railway track switch Mathematical modelling Redundant actuation Finite element analysis

Cytokine landscapes of pregnancy:mapping gestational immune phases

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Gynecology and Obstetrics Clinical Medicine 2024年第1期4卷 56-64页

作者： sulagna dutta Pallav sengupta Fong Fong Liew Basic Medical sciences Department College of MedicineAjman UniversityAjmanUAE Department of Biomedical sciences Gulf Medical UniversityAjmanUAE Department of Preclinical sciences Faculty of DentistryMAHSA UniversityKuala LumpurMalaysia

Background synchronised physiological adaptations occur during pregnancy to achieve systemic,immune and neuroendocrine equilibrium in the mother's body,allowing semiallogenic fetal *** text Depending on the cytokine profile alterations occurring through pregnancy,the latter can be divided into three distinct *** the first immunological phase of pregnancy,proinflammatory cytokines promote inflammatory reactions needed for *** the second phase,a possible change from proinflammatory to anti-inflammatory cytokines creates a symbiosis between maternal and fetal components,ensuring fetal *** the third phase,inflammatory and cytolytic cytokines operate again to reinforce an inflammatory environment for *** article offers a detailed account of immune adaptations during pregnancy and highlights the distinctive cytokine profiles that mark each *** By providing a simplified depiction of pregnancy phases based on cytokine profiles,the article aims to inspire more research in reproductive immunology and improve the management of pregnancy-related inflammation and infection.

关键词： pregnancy mother alterations

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

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Nano-Micro Letters 2024年第3期16卷 1-35页

作者： sourav dutta seungmin Noh Roger sanchis Gual Xiangzhong Chen salvador Pané Bradley J.Nelson Hongsoo Choi Department of Robotics and Mechatronics Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea DGIsT‑ETH Microrobotics Research Center DGISTDaegu 42988Republic of Korea Multi‑scale Robotics Lab Institute of Robotics and Intelligent SystemsETH Zurich8092 ZurichSwitzerland Institute of Optoelectronics State Key Laboratory of Photovoltaic Science and TechnologyShanghai Frontiers Science Research Base of Intelligent Optoelectronics and PerceptionFudan UniversityShanghai 200433People’s Republic of China

synthetic micromotor has gained substantial attention in biomedicine and environmental ***-based degradable micromotor composed of magnesium(Mg),zinc(Zn),and iron(Fe)have promise due to their nontoxic fuel-free propulsion,favorable biocompatibility,and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media,efficient cargo delivery and favorable biocompatibility.A noteworthy number of degradable metal-based micromotors employ bubble propulsion,utilizing water as fuel to generate hydrogen *** novel feature has projected degradable metallic micromotors for active in vivo drug delivery *** addition,understanding the degradation mechanism of these micromotors is also a key parameter for their design and *** propulsion efficiency and life span govern the overall performance of a degradable metallic *** we review the design and recent advancements of metallic degradable ***,we describe the controlled degradation,efficient in vivo drug delivery,and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical ***,we discuss micromotors’efficacy in detecting and destroying environmental ***,we address the limitations and future research directions of degradable metallic micromotors.

关键词： Magnesium Zinc Iron Biodegradable microrobot Biomedical Environmental