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Lakshmanan, N.,Raghuprasad, B.K.,Gopalakrishnan, N.,Sreekala, R.,Rama Rao, G.V. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6
The paper proposes two methodologies for damage identification from measured natural frequencies of a contiguously damaged reinforced concrete beam, idealised with distributed damage model. The first method identifies damage from Iso-Eigen-Value-Change contours, plotted between pairs of different frequencies. The performance of the method is checked for a wide variation of damage positions and extents. The method is also extended to a discrete structure in the form of a five-storied shear building and the simplicity of the method is demonstrated. The second method is through smeared damage model, where the damage is assumed constant for different segments of the beam and the lengths and centres of these segments are the known inputs. First-order perturbation method is used to derive the relevant expressions. Both these methods are based on distributed damage models and have been checked with experimental program on simply supported reinforced concrete beams, subjected to different stages of symmetric and un-symmetric damages. The results of the experiments are encouraging and show that both the methods can be adopted together in a damage identification scenario.
Lakshmanan, Pandian,Kim, Dong Ha,Park, Eun Duck American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.5
<P>We examined the effect of the particle size of gold on steam reforming of methanol over Au/CeO2-ZrO2 catalysts. Gold was loaded onto CeO2-ZrO2 through deposition-precipitation. The average particle size (2-12 nm) of the gold was controlled by thermal reduction under H-2 at various temperatures and by chemical reduction with various reducing agents. The catalytic activity decreased significantly with increasing particle size of the gold. The turnover frequency at the interface between gold and a support appeared to be independent of particle size in the range 2-5 nm, which implies that the perimeter of the particle may be the active site for this reaction. Methanol adsorption and conversion over these catalysts were also investigated with in-situ diffuse reflectance infrared Fourier transform spectroscopy. Analytical results for various adsorbed intermediate species during methanol conversion suggests that transformation of methoxy species is facilitated by use of smaller gold particles.</P>
Wavelet analysis and enhanced damage indicators
Lakshmanan, N.,Raghuprasad, B.K.,Muthumani, K.,Gopalakrishnan, N.,Basu, D. Techno-Press 2007 Smart Structures and Systems, An International Jou Vol.3 No.1
Wavelet transforms are the emerging signal-processing tools for damage identification and time-frequency localization. A small perturbation in a static or dynamic displacement profile could be captured using multi-resolution technique of wavelet analysis. The paper presents the wavelet analysis of damaged linear structural elements using DB4 or BIOR6.8 family of wavelets. Starting with a localized reduction of EI at the mid-span of a simply supported beam, damage modeling is done for a typical steel and reinforced concrete beam element. Rotation and curvature mode shapes are found to be the improved indicators of damage and when these are coupled with wavelet analysis, a clear picture of damage singularity emerges. In the steel beam, the damage is modeled as a rotational spring and for an RC section, moment curvature relationship is used to compute the effective EI. Wavelet analysis is performed for these damage models for displacement, rotation and curvature mode shapes as well as static deformation profiles. It is shown that all the damage indicators like displacement, slope and curvature are magnified under higher modes. A localization scheme with arbitrary location of curvature nodes within a pseudo span is developed for steady state dynamic loads, such that curvature response and damages are maximized and the scheme is numerically tested and proved.
Compatibility of Lithium ion Phosphate Battery in Solar off Grid Application
Lakshmanan, Sathishkumar,Vetrivel, Dhanapal,Subban, Ravi,R., Saratha,Nanjan, Sugumaran The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.4
Solar energy harvesting is practiced by various nations for the purpose of energy security and environment preservation in order to reduce overdependence on oil. Converting solar energy into electrical energy through Photovoltaic (PV) module can take place either in on-grid or off-grid applications. In recent time Lithium battery is exhibiting its presence in on-grid applications but its role in off-grid application is rarely discussed in the literature. The preliminary capacity and Peukert's study indicated that the battery quality is good and can be subjected for life cycle test. The capacity of the battery was 10.82 Ah at 1 A discharge current and the slope of 1.0117 in the Peukert's study indicated the reaction is very fast and independent on rate of discharge. In this study Lithium Iron Phosphate battery (LFP) after initial characterization was subjected to life cycle test which is specific to solar off-grid application as defined in IEC standard. The battery has delivered just 6 endurance units at room temperature before its capacity reached 75% of rated value. The low life of LFP battery in off-grid application is discussed based on State of Charge (SOC) operating window. The battery was operated both in high and low SOC's in off-grid application and both are detrimental to life of lithium battery. High SOC operation resulted in cell-to-cell variation and low SOC operation resulted in lithium plating on negative electrode. It is suggested that to make it more suitable for off-grid applications the battery by default has to be overdesigned by nearly 40% of its rated capacity.
Lakshmanan, P.,Park, J.E.,Kim, B.,Park, E.D. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.265 No.-
<P>The preferential oxidation of CO (CO-PROX) under excess hydrogen over Au/MOx/Al2O3 (M = La, Ce, and Mg) catalysts was investigated. All catalysts were prepared by a deposition-precipitation method with urea and characterized with inductively coupled plasma-atomic emission spectroscopy, N-2 physisorption, temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy. The catalytic activity of the supported gold catalysts was found to be dependent on the promoter, and decreased in the order: Au/La2O3/Al2O3 > Au/CeO2/Al2O3 > Au/MgO/Al2O3 > Au/Al2O3. The catalytic activity of the Au/La2O3/Al2O3 catalyst depended on the pretreatment conditions, i.e., reduction with aqueous NaBH4, thermal reduction with H-2, and calcination with O-2. This indicates that the oxidation state of gold is an important factor in the activity of the catalyst, and that metallic gold is more suitable than its oxidized form for this reaction. XPS results revealed that the treatment with aqueous NaBH4 resulted in more negative charge in gold particles than that of conventional thermal reduction under H-2. Smaller gold particles appeared to be favorable for the low-temperature CO-PROX activity of the Au/La2O3/Al2O3 catalysts, which showed stable CO-PROX performance, even in the presence of CO2. (C) 2015 Elsevier B.V. All rights reserved.</P>
Lakshmanan, Meiyappan,Zhang, Zhaoyang,Mohanty, Bijayalaxmi,Kwon, Jun-Young,Choi, Hong-Yeol,Nam, Hyung-Jin,Kim, Dong-Il,Lee, Dong-Yup American Society of Plant Biologists 2013 PLANT PHYSIOLOGY - Vol.162 No.4
<P><I>A metabolic/regulatory network of rice incorporates two important tissue types, germinating seeds and photorespiring leaves, is validated through experiments with rice suspension cultures, and applied to analyze metabolic capability under flooding and drought conditions.</I></P>