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51.
Vangipuram S. Ramachandran Rolf F. Feldman 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1973,23(8):625-633
Hydration characteristics are reported of tricalcium aluminate studied at 20 and 80 °C using water-solid ratios of 0.2 and 1.0. Hydration products were subjected to differential thermal analysis, thermogravimetric analysis, scanning electron microscopy, length change, porosity and pore size distribution, and micro-hardness measurements. Hydration proceeds faster at 80 °C than at 20 °C and the cubic C3AH6 phase is detected in the first few seconds. At 20 °C hydration occurs with the initial formation of the hexagonal phases and expansion is continuous. At higher temperatures and a water-solid ratio of 0.2, after an initial small expansion, the dimensional change is low. The product at 80 °C develops more than fourfold the hardness value developed at 20 °C. After 2 days of hydration, porosity, per cent C3AH6 and microhardness are 15.2%, 83% and 38.9 kg/mm2; corresponding values for the product obtained at 20 °C are 21.5%, 75% and 9.1 kg/mm2. Microstructural examination of the material formed at 80 °C indicates a closely welded and continuous network of the cubic phase. These results reveal that at a low water-solid ratio and higher temperatures the formation of the cubic phase from C3A results in an enhancement of strength. 相似文献
52.
A method for realising a v.t.f.by a nonsymmetrical lattice in which all coils can be made lossy is given. 相似文献
53.
54.
Plates with central through cracks subjected to bending is analysed taking into account the closure of the crack faces on the compression side. A three-dimensional finite element method employing three-dimensional degenerate solid element is used for the analysis. The crack faces have been modelled such that they come in contact over an area on the compression side and interfere with each other. The influence of the crack closure on the variation of the stress intensity factor across the plate thickness is obtained for finite and infinite plate geometries. 相似文献
55.
J. Ramachandran 《Computers & Structures》1974,4(4):871-877
In this paper, a method of analysing large amplitude vibrations of circular plates with mixed boundary conditions is explained and is illustrated with an example where part of the boundary is clamped and the remaining simply-supported 相似文献
56.
Ismail Omar Hababeh Muthu Ramachandran Nicholas Bowring 《The Journal of supercomputing》2007,39(1):3-18
Enhancing the performance of the DDBs (Distributed Database system) can be done by speeding up the computation of the data allocation, leading to higher speed allocation decisions and resulting
in smaller data redundancy and shorter processing time. This paper deals with an integrated method for grouping the distributed
sites into clusters and customizing the database fragments allocation to the clusters and their sites. We design a high speed
clustering and allocating method to determine which fragments would be allocated to which cluster and site so as to maintain
data availability and a constant systemic reliability, and evaluate the performance achieved by this method and demonstrate
its efficiency by means of tabular and graphical representation. We tested our method over different network sites and found
it reduces the data transferred between the sites during the execution time, minimizes the communication cost needed for processing
applications, and handles the database queries and meets their future needs. 相似文献
57.
S. K. Patra Manish Shekher S. S. Solanki R. Ramachandran R. Krishnan 《International journal of remote sensing》2013,34(14):2977-2989
Colour is widely used in remote sensing work. In many instances, the use of colour conveys additional information both visually and scientifically. Remote sensing satellites view the earth in different spectral bands, viz. near infrared (NIR), red, green, and blue bands, in a conventional multispectral imaging system. In the absence of a blue channel, colour images can be generated using near infrared, red, and green bands in what is known as a false colour composite (FCC) and does not look natural, like the image we see with the naked eye. For a trained interpreter, this does not pose any problems. However, when the intended use is a fly‐through of a draped terrain, visual interpretation, or a display, meant for the non‐remote sensing professional, this becomes a handicap. To overcome this, there is a requirement to generate natural colour composites (NCC) from the given false colour composite, which demands the simulation of a blue band to be combined with green and red bands. This paper describes a unique method of generating a blue band to form natural colour images from a given false colour image set. We use a spectral transformation method to establish a relationship between the false colour and true colour image pairs provided by a sensor with all the four bands, which has a broader spectral coverage. A transformation function is fitted by selecting radiometric control points along the line of geometric registration to find a set of coefficients to be used for simulating a blue band. This blue band, along with the green and red bands, provides a near true colour or ‘natural colour’ on the display. In this paper, we present a set of adjustable radiometric transformation coefficients to accommodate variation in spatial and dynamic range offered by sensors to generate natural colour. These coefficients seem to work on a large number of images of different seasons, provided similar spectral bands and terrain are used. The proposed ‘natural colour generator’ can be used in changing false colour images to natural colour images with the aim of ‘what you get is what you would have seen’. 相似文献
58.
K. Nalini K. N. Uma S. Sijikumar Yogesh K. Tiwari Radhika Ramachandran 《International journal of remote sensing》2013,34(22):7881-7900
ABSTRACTThe present study demonstrates the distribution of carbon dioxide (CO2) concentration over the Indian region and the surrounding oceanic regions during 2009–2012, using measurements from satellites viz., Greenhouse Gases Observing Satellite (GOSAT) and Atmospheric Infrared Sounder, Carbon Tracker (CT) model simulations and flask measurements from two Indian stations Sinhagad (SNG) (73°45′ E, 18°21′36″ N) and Cape Rama (CRI) (73°54′ E, 15°6′ N). The concentration of CO2 is observed to be maximum during pre-monsoon and shows a decreasing phase during the post-monsoon season. In a regional scale, it is found that Indo-Gangetic Plain and northern India have relatively higher concentrations compared to the other regions. The probability distribution of the concentration differences shows that for most of the time, the differences lie between ±3 ppmv between GOSAT and CT. The comparison between the CO2 flask measurements over SNG and CRI with respect to that of GOSAT and CT clearly reveals that the differences in CO2 are as high as 10 ppmv between the ground- and satellite-based measurements. Further, we utilized the Lagrangian model FLEXible PARTicle (FLEXPART) to understand the source?receptor relationship over CRI, SNG, and over the equatorial Indian Ocean (IO). The source contributions from the northern and eastern continental regions of the Indian region are found to be more influential over SNG compared to CRI. It is also found from simulations that the equatorial IO has less influence from the continental source and therefore has a reduced seasonal variability compared to the other regions considered in the present study. 相似文献
59.
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
60.
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