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Panda R.K.,Larsen and Toubro Ltd | Veeramalla J.,Larsen and Toubro Ltd
1st IEEE International Conference on Power Electronics, Intelligent Control and Energy Systems, ICPEICES 2016 | Year: 2016

Unlike to current transformer, a residual current sensor is highly sensitive to the input leakage current and core material. It senses the leakage current that is produced due to faulty condition in the electrical circuit or unintentional body touch to the equipment through conductive tracking of the insulation medium. The leakage current which the sensor detects consists of ac residual current with fixed or multiple frequencies, pure dc, half or full wave pulsed dc and mixed leakage current along with high frequency. A conventional current transformer will not be able to detect such current. At the outset, the paper explains in detail about various sensing technologies applicable to a residual current device. MATLAB simulation result shows the effect of different input leakage current upon the output characteristics of CBCT. Pspice simulation explains about the signal conditioning of the CBCT output for actuation of the tripping mechanism of the RCD. Later part of the paper explains about its behavior modeling due to external magnetic field interference. It suggests about means of shielding against external magnetic field. Transient electromagnetic analysis shows that by means of shielding the CBCT using a low permeable material, the performance of RCD can be improved. © 2016 IEEE.

Sarma B.S.,Larsen and Toubro Ltd
fib Symposium PRAGUE 2011: Concrete Engineering for Excellence and Efficiency, Proceedings | Year: 2011

In situations like congestion of reinforcement in mega structures of beam and column elements, or retrofitting of structures, or to improve construction sites with less noise and to improve productivity, concrete with self compacting characteristics is often preferred in construction industry. In general the flow characterisation can be defined through slump spread at field level. Indigenously developed rheometer at L&T-R&D centre was supplemented to develop high flow concrete. The rheology of conventional and self compacting concrete (SCC) were compared. This paper highlights the details of mix of 100MPa of SCC and vibrated conventional concrete (VCC). Considering practical constraints in transportation of concrete at site, mix was designed to retain the workability for at least 90 minutes period. Based on this study it is emphasized that in todays' context defining the characteristic strength only at 28th day will cause severe environmental challenges and financial constraints in industry. By limiting the cement content below 450 kg/m 3 and with the appropriate choice of supplemental cementitious materials high strength concrete strength should be expressed at 56th or 93rd day. This will conserve cement content and promote green products utilisation like flyash, blast fumace slag, rice husk ash etc, and results into development of more and more green concrete products and also economical for project execution.

Yadav S.,P.A. College | Kaushal M.,Larsen and Toubro Ltd. | Varun,National Institute of Technology Hamirpur | Siddhartha,National Institute of Technology Hamirpur
Solar Energy | Year: 2014

Solar energy is a clean, abundant and easily available source of energy. Thermal performance of solar air heater does not take into account the energy loss due to friction for propelling air through the duct. In this work an attempt has been made to evaluate exergetic efficiency of roughened solar air heater duct provided with protrusions arranged in arc fashion over the absorber plate. The exergetic efficiency of a solar air heater was calculated analytically using developed correlations and the results were compared with that of a smooth flat-plate solar air heater. Design plots were also prepared in order to facilitate the designer for designing such type of roughened solar air heater within the investigated range of system and operating parameters. © 2014 Elsevier Ltd.

To gain access to new markets and technology resources, as well as low-cost and multi-currency-based sourcing and offset obligations, major Original Equipment Manufacturers (OEMs) are expanding their footprint in Asia. It is mandatory to have EASA/FAA approvals including Civil Aviation Airworthiness approvals by DGCA, India for organizations engaged in manufacture of an aircraft/ component/ item of equipment or part to export products for commercial aircraft applications. Reyaneh Sayafi, Florence Leblond developed a Production Organization Exposition scheme taking into account EN9100 requirements. The objective was to study requirements of AS/EN9100, EASA, FAA and DGCA (India) to harmonize and prepare a concise Production Organization Exposition (POE) that complies with all requirements. This paper includes development of Production Organization Exposition (POE) manual to incorporate requirements of Quality Management Systems- Requirements for Aviation, Space and Defense Organizations (AS/EN 9100), European Aviation Safety Agency (EASA) Part 21 G, Federal Aviation Administration (FAA) CFR 14 Part 21 G and DGCA, India Part 21 Subpart G. A detailed comparison of AS/EN 9100, EASA, FAA and DGCA (India) requirements of Production Organization Exposition (POE) is conducted. A cross reference matrix has been prepared. For each important topic, it covers regulations, similarities and differences and then a harmonization which defines a common structure of procedures of Production Organization Exposition (POE) incorporating AS/EN9100, EASA, FAA and DGCA (India) requirements. Efforts in planning stage will ensure stringent requirements are deployed and enable minimum preparation time required to take up approvals from Civil Aviation Authorities. © 2014 Published by Elsevier Ltd.

Sivaramakrishnan S.,Larsen and Toubro Ltd
2015 International Conference on Computing and Network Communications, CoCoNet 2015 | Year: 2015

Owing to the non-linear characteristics of the Photovoltaic (PV) Module, Maximum Power Point Tracking (MPPT) algorithms to obtain the maximum power out of a PV module are gaining popularity over the years. This paper proposes a novel hybrid MPPT algorithm, which uses a combination of linear extrapolation and perturb and observe algorithm to determine the maximum power point of a PV module. Since the traditional perturb and observe (P&O) MPPT algorithm has the disadvantages of being slow, inaccurate and incorrect response to rapidly varying environmental conditions, the proposed algorithm is proven to be faster and more accurate in tracking MPP than the former. A C-program was coded to validate the proposed algorithm and the results are compared with P&O method. © 2015 IEEE.

Sivaramakrishnan S.,Larsen and Toubro Ltd
2016 - Biennial International Conference on Power and Energy Systems: Towards Sustainable Energy, PESTSE 2016 | Year: 2016

With increase in consumption of fobil fuels, the requirement for utilizing renewable energy is on the raise. Solar energy being one of them can be converted into electrical energy with the help of photovoltaic (PV) modules. But these modules have nonlinear Power-Voltage (P-V) characteristics due to which several algorithms have been proposed to estimate the Maximum Power Point (MPP) of a PV module. Fractional Open Circuit voltage (FOCV) is one of the simplest Maximum Power Point Tracking (MPPT) algorithms by which impedance matching can be done in a PV system. FOCV requires periodic determination of open circuit voltage to approximate MPP of the PV panel being used, which results in temporary lob of power. In this article, an alternative approach, Linear extrapolated MPPT (LEMPPT) is used to approximate MPP which doesn't require the disconnection of load and since the load disconnection directly affects the sampling rate, LEMPPT has an added advantage of being able to sample frequently thereby making it more responsive to the environment. The proposed algorithm was designed in Matlab/SIMULINK and the results are compared with FOCV technique. © 2016 IEEE.

Patel G.,Larsen and Toubro Ltd
2012 3rd International Conference on Computing, Communication and Networking Technologies, ICCCNT 2012 | Year: 2012

In Healthcare IT-driven revolution the organizations are investing in the latest information technologies with the clear goals of reducing operating costs and improving healthcare outcomes. Cloud computing is emerging as a new trend in computational and storage resource allocation and provisioning technology. The motivation of study is providing DICOM images management on Cloud Computing technology for authorized physicians, healthcare facilities and on demand access to patient's medical images from RIS or PACS. The proposed work is discussed to meet the challenges for DICOM Image Management and the offered cloud service model 'Cloud as a Service (CaaS)' for Medical Imaging applications on cloud computing systems. The conceptual design is discussed, how to manage medical imaging solution on cloud, though to provide secure service, anytime & anywhere access to medical images and instant retrieval of digital images data of any modality with a cloud-based image storage and management service using standard DICOM protocol. This paper summarizes the framework model on medical imaging solid foundation with platforms and softwares to power the cloud infrastructure for DICOM Image Management, build and run robust cloud applications, and supply end-user computing as a cloud-based service. © 2012 IEEE.

Prabu P.M.A.,Larsen and Toubro Ltd
2014 Annual International Conference on Emerging Research Areas: Magnetics, Machines and Drives, AICERA/iCMMD 2014 - Proceedings | Year: 2014

It is important to understand magnetic fields and their interactions in electrical equipments, transmission cables etc. But very often, visualizing magnetic fields is a difficult task. For this purpose, engineers make use of various Finite Element Analysis (FEA) softwares. In many cases, these commercial softwares are expensive and cumbersome to use. This paper illustrates a method to compute and visualize magnetic fields in two dimensions using a MS Excel Spreadsheet. The finite difference method is used to solve Maxwell's equations. The results of computation are shown and the same is compared with commercial FEA software. © 2014 IEEE.

Dholakia Y.N.,Larsen and Toubro Ltd | Shah D.P.,Municipal Corporation of Greater Mumbai
Lung India | Year: 2013

Background: Characteristics and treatment outcomes of patients with drug-resistant tuberculosis (DR TB) before introduction of directly observed treatment strategy (DOTS) plus are infrequently reported. Aims: To study clinical characteristics and treatment outcomes of drug-resistant TB patients. Setting: A TB unit in Mumbai. Materials and Methods: A retrospective analysis of DR TB patients attending a TB unit and taking treatment at NGOs was performed. Of the 34 cases, 5 (14%) had mycobacterium other than tuberculosis, 24 were pulmonary TB, 4 extra-pulmonary TB, and one both. Three were HIV-infected, two had diabetes. Two cases were treatment naive. Of the 29 cases studied, 3 (11%) were mono-resistant, 20 (69%) were multidrug-resistant (MDR) TB with E/Z/EZ resistance; 4 were pure MDR TB. One case had XDR TB, 13 (44.8%) had resistance to at least one conventional second-line drug. Seven cases had adverse drug reaction, four requiring drug substitution. Two patients are on treatment; 14 of the remaining 27 (51%) were successfully treated, 5 (18%) died, 2 (7%) failed treatment, 5 (18%) were lost to follow-up, one migrated. Conclusion: DST profiles suggest high levels of drug resistance due to amplification which leads to poor outcomes. There is an urgent need for Indian Revised National TB Control Program to introduce daily DOTS for susceptible cases, DST for all new cases, and scaling up DST for second-line drugs. There is also a need to use individualized treatment for DR TB.

Jha K.N.,Indian Institute of Technology Delhi | Chockalingam C.T.,Larsen and Toubro Ltd
Construction Management and Economics | Year: 2011

Approximately 42% of Indian government-funded construction projects are facing time overruns. With a number of challenging projects around the corner, there is a definite need to overcome these delays. In an earlier study conducted by one of the authors, 55 project performance attributes were identified based on expert opinions and literature surveys, which were subsequently reduced to 20 factors (11 success and nine failure factors) using factor analysis. A second-stage questionnaire survey based on these factors was used to identify the significant schedule performance factors. The analysis of the survey responses led us to conclude that factors such as: a project manager's competence; monitoring and feedback by project participants; commitment of all project participants; owner's competence; interaction between external project participants; and good coordination between project participants significantly affect schedule performance. The survey also provided the basis for the development of a schedule performance prediction model. For this, an artificial neural network (ANN) method was used to construct the model, and the best was determined to be a 6-3-1 feed-forward neural network based on a back-propagation algorithm with a mean absolute percentage deviation (MAPD) of 11%. This enables project team members to understand the factors they must monitor closely in order to complete the projects on schedule and to predict performance throughout the course of the project. © 2011 Taylor & Francis.

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