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61.
Andrea Polidori Barbara J. Turpin Ho-Jin Lim † Juan C. Cabada †† Ramachandran Subramanian ††† Spyros N. Pandis †††† 《Aerosol science and technology》2013,47(10):861-872
We present Scanning Mobility CCN Analysis (SMCA) as a novel method for obtaining rapid measurements of size-resolved cloud condensation nuclei (CCN) distributions and activation kinetics. SMCA involves sampling the monodisperse outlet stream of a Differential Mobility Analyzer (DMA) operated in scanning voltage mode concurrently with CCN and condensation particle counters. By applying the same inversion algorithm as used for obtaining size distributions with a scanning mobility particle sizer (SMPS), CCN concentration and activated droplet size are obtained as a function of mobility size over the timescale of an SMPS scan (typically 60–120 s). Methods to account for multiple charging, particle non-sphericity, and limited counting statistics are presented. SMCA is demonstrated using commercial SMPS and CFSTGC instruments with the manufacturer-provided control software. The method is evaluated for activation of both laboratory aerosol and ambient aerosol obtained during the 2004 NEAQS-ITCT2k4 field campaign. It is shown that SMCA reproduces the results obtained with a DMA operating in voltage “stepping” mode. 相似文献
62.
M. Ramachandran R. G. Reddy 《JOM Journal of the Minerals, Metals and Materials Society》2011,63(1):44-46
Nanoscale materials have been considered for and been in use in a variety of industrial engineering applications. The surface tension of silver and copper were calculated at various temperatures using non-ideal or real solution characteristics. The surface concentration of individual components was also calculated. The surface concentration of silver in a binary silver copper system is higher in spite of its lower surface tension as a pure component. It is also shown that the melting temperature of individual elements decrease with decrease in particle size. This trend is true for most metallic elements and is pronounced below a particle size of 20 nm. 相似文献
63.
Nanostructured porous InP samples were prepared by electrochemical anodic dissolution of InP for various current densities
and etching periods. The samples were characterized by SEM and photoluminescence (PL) where a blue shift was observed in PL.
Thermal properties studied by photoacoustic (PA) spectroscopy revealed one order decrease in thermal conductivity of porous
InP compared to the bulk. Further it is shown that the thermal conductivity of porous InP decreases with decrease in size
of the particles. 相似文献
64.
NS Ramachandran 《纯碱工业》2000,(5):56-58
1 简介 印度第一个纯碱厂始建于1932年,位于印度西部古吉拉特邦的Dhrangadhra,装置能力为50t/d。 作为基础无机化工产品,因为整个印度无天然碱矿,全部产品--包括轻灰和重灰只能以合成法生产。 相似文献
65.
Principal components analysis (PCA) is a multivariate statistical technique that transforms a data set having a large number of inter-related variables to a new set of uncorrelated variables called the principal components, determined to allow the dimensionality of the data set to be reduced while retaining as much of the variation present as possible. PCA can be applied to dynamic structural response data to identify the predominant modes of vibration of the structure. Because PCA is a statistical technique, there are errors in the computed modes due to the use of a sample of finite size. The aim of this paper is to study the effect of sample size on the accuracy with which the modes of vibration can be computed. The paper focuses predominantly on elastic response data and examines the potential influence of various parameters such as the period of the structure, the input excitation, and the spatial distribution of mass over the structure. Issues relating to errors in the modes of nonlinear structures are also discussed. 相似文献
66.
PK Ramachandran Nair 《Journal of the science of food and agriculture》2007,87(9):1613-1619
The success of modern agricultural and forestry production can be largely attributed to monoculture systems using a few select species. In the drive for maximizing yield and profit, the age‐old tradition of using combined farming systems was essentially avoided and in some cases this has resulted in environmental problems such as land and water degradation and increased land clearing. During the last 30 years, however, the positive benefits of agroforestry to the producer and the environment have been increasingly recognized. Combining trees and crops in spatial or temporal arrangements has been shown to improve food and nutritional security and mitigate environmental degradation, offering a sustainable alternative to monoculture production. By providing supportive and complimentary roles with a flexible approach, agroforestry can offer specific social and environmental benefits across a range of landscapes and economies. More research and effort is needed to explore the full potential of agroforestry applications and to fuel awareness. As the plethora of benefits of agroforestry are realized, modern land‐use systems are evolving towards a more sustainable and holistic approach to land management. Copyright © 2007 Society of Chemical Industry 相似文献
67.
68.
Ruoyu Su Ramachandran Venkatesan Cheng Li 《Wireless Communications and Mobile Computing》2016,16(9):1158-1172
In addition to the requirements of the terrestrial sensor network where performance metrics such as throughput and packet delivery delay are often emphasized, energy efficiency becomes an even more significant and challenging issue in underwater acoustic sensor networks, especially when long‐term deployment is required. In this paper, we tackle the problem of energy conservation in underwater acoustic sensor networks for long‐term marine monitoring applications. We propose an asynchronous wake‐up scheme based on combinatorial designs to minimize the working duty cycle of sensor nodes. We prove that network connectivity can be properly maintained using such a design even with a reduced duty cycle. We study the utilization ratio of the sink node and the scalability of the network using multiple sink nodes. Simulation results show that the proposed asynchronous wake‐up scheme can effectively reduce the energy consumption for idle listening and can outperform other cyclic difference set‐based wake‐up schemes. More significantly, high performance is achieved without sacrificing network connectivity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
69.
In the present study, hydroxyapatite (HAP) coating along with HAP/TiO2 coating has been deposited by high-velocity flame spray (HVFS) technique onto 316LSS. Titania was used as a bond coat and HAP as top coat in HAP/TiO2 coating. The main aim of the study is to investigate the corrosion behavior of thermal spray coating of HAP and HAP/TiO2 on steel. Electrochemical corrosion testing was carried out using potentiodynamic polarization test. The corrosion behavior of bare and as-sprayed specimens was analyzed in simulated body fluid known as Hank’s solution. As-sprayed specimens along with corroded specimens were further characterized by XRD, SEM/EDS, and x-ray mapping analysis. It was observed that the HAP/TiO2 coating possessed higher microhardness (280 Hv) as compared to HAP coating (254 Hv). Surface roughness also got enhanced in case of HAP/TiO2 coating (9.35 μm) as compared to pure HAP coating (7.37 μm). The porosity of the HAP coating was found to be higher than the bond coating. It was observed that the Ca/P ratio almost resembled that of the natural bone composition. The corrosion resistance of steel increased after the deposition of HAP and HAP/TiO2 coatings. The maximum corrosion resistance was exhibited by HAP/TiO2 coating. 相似文献
70.
Kening Gong Bala Subramaniam Palghat A. Ramachandran Keith W. Hutchenson 《American Institute of Chemical Engineers》2010,56(5):1285-1296
A TEOM is used to elucidate the adsorption/desorption characteristics of alkylation reactants on USY‐ and β‐zeolites. Equilibrium adsorption isotherms were obtained on USY‐ and β‐zeolites using n‐butane, isobutane and propane as proxy reactant molecules (T = 303–398 K, adsorbate partial pressure 0–1.2 bar). Analysis of the transient adsorption/desorption profiles of these molecules from either a bed of the zeolite or pelletized particles of the crystals (with mean size < 1 μm) demonstrate that diffusion in the secondary meso‐/macroporous structure formed in the packing or the pellets controls the overall sorption rates. The experimental adsorption/desorption profiles from the pelletized zeolites were regressed with available mathematical models to obtain effective meso‐/macropore diffusivities for reactant molecules, and nearly perfect fits of the experimental and the modeled profiles. Taking into account the dead volume in the system, a criterion for reliable measurements of either micropore or mesopore diffusivities by the TEOM technique is derived. © 2009 American Institute of Chemical Engineers AIChE J, 2010 相似文献