146 research outputs found

    THE DESIGN OF AN IC HALF PRECISION FLOATING POINT ARITHMETIC LOGIC UNIT

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    A 16 bit floating point (FP) Arithmetic Logic Unit (ALU) was designed and implemented in 0.35µm CMOS technology. Typical uses of the 16 bit FP ALU include graphics processors and embedded multimedia applications. The ALU of the modern microprocessors use a fused multiply add (FMA) design technique. An advantage of the FMA is to remove the need for a comparator which is required for a normal FP adder. The FMA consists of a multiplier, shifters, adders and rounding circuit. A fast multiplier based on the Wallace tree configuration was designed. The number of partial products was greatly reduced by the use of the modified booth encoder. The Wallace tree was chosen to reduce the number of reduction layers of partial products. The multiplier also involved the design of a pass transistor based 4:2 compressor. The average delay of the pass transistor based compressor was 55ps and was found to be 7 times faster than the full adder based 4:2 compressor. The shifters consist of separate left and right shifters using multiplexers. The shift amount is calculated using the exponents of the three operands. The addition operation is implemented using a carry skip adder (CSK). The average delay of the CSK was 1.05ns and was slower than the carry look ahead adder by about 400ps. The advantages of the CSK are reduced power, gate count and area when compared to the similar sized carry look ahead adder. The adder computes the addition of the multiplier result and the shifted value of the addend. In most modern computers, division is performed using software thereby eliminating the need for a separate hardware unit. FMA hardware unit was utilized to perform FP division. The FP divider uses the Newton Raphson algorithm to solve division by iteration. The initial approximated value with five bit accuracy was assumed to be pre-stored in cache memory and a separate clock cycle for cache read was assumed before the start of the FP division operation. In order to significantly reduce the area of the design, only one multiplier was used. Rounding to nearest technique was implemented using an 11 bit variable CSK adder. This is the best rounding technique when compared to other rounding techniques. In both the FMA and division, rounding was performed after the computation of the final result during the last clock cycle of operation. Testability analysis is performed for the multiplier which is the most complex and critical part of the FP ALU. The specific aim of testability was to ensure the correct operation of the multiplier and thus guarantee the correctness of the FMA circuit at the layout stage. The multiplier\u27s output was tested by identifying the minimal number of input vectors which toggle the inputs of the 4:2 compressors of the multiplier. The test vectors were identified in a semi automated manner using Perl scripting language. The multiplier was tested with a test set of thirty one vectors. The fault coverage of the multiplier was found to be 90.09%. The layout was implemented using IC station of Mentor Graphics CAD tool and resulted in a chip area of 1.96mm2. The specifications for basic arithmetic operations were met successfully. FP Division operation was completed within six clock cycles. The other arithmetic operations like FMA, FP addition, FP subtraction and FP multiplication were completed within three clock cycles

    Chemical patterning for the highly specific and programmed assembly of nanostructures

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    We have developed a new chemical patterning technique based on standard lithography-based processes to assemble nanostructures on surfaces with extraordinarily high selectivity. This patterning process is used to create patterns of aminosilane molecular layers surrounded by highly inert poly (ethylene glycol) (PEG) molecules. While the aminosilane regions facilitate nanostructure assembly, the PEG coating prevents adsorption of molecules and nanostructures, thereby priming the semiconductor substrate for the highly localized and programmed assembly of nanostructures. We demonstrate the power and versatility of this manufacturing process by building multilayered structures of gold nanoparticles attached to molecules of DNA onto the aminosilane patterns, with zero nanocrystal adsorption onto the surrounding PEG regions. The highly specific surface chemistry developed here can be used in conjunction with standard microfabrication and emerging nanofabrication technology to seamlessly integrate various nanostructures with semiconductor electronics

    Impact of climate change on hydrology of Manjalar sub basin of river Vaigai in Tamil Nadu, India

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    This study evaluates the impacts of possible future climate change scenarios on the hydrology of the catchment area of the Manjalar sub basin of River Vaigai, Tamil Nadu, India carried out at the department of Soil and Water Conservation Engineering, Tamil Nadu Agricultural University during the period of 2011-2014 using Soiland Water Assessment Tool (SWAT). For the climate impact assessment the hydrological model was driven with output of bias corrected Earth System Models of the Coupled Model Intercomparison Project Phase 5 (CMIP5): HadGEM2. Climate scenarios were downscaled to a grid resolution of 0.22° x 0.22°. In this study RCP 4.5 and RCP 8.5 were included for future assessment with three future periods: 2012–2039, 2040–2069, and 2070–2098. The projected increase in maximum and minimum temperature for RCP 4.5 scenario is 0.8 to 2.3 ºC and 0.7 to 1.6 ºC and for RCP 8.5 scenario is 1.1 to 4.0 ºC and 1.0 to 3.1 ºC, respectively. Rainfall is projected to an increase between 9.2 to 15.2 per cent for RCP 4.5 scenario and an increase of 13.6 to 18.8 per cent for RCP 8.5 scenario during 21st century. The soil water storage and stream flow contribution to ground water are likely to increase in RCP 4.5 scenario and it would again decline for RCP 8.5 scenario during 21st century. The increase in annual rainfall evapotranspiration and surface runoff would be more in RCP 8.5 scenario compared to RCP 4.5 scenario. The possible changes projected by the study provide a useful input to effective planning of water resources of the study area

    Generating cadastral base for Kolathupalayam village in Tamil Nadu from high resolution LISS IV sensor data

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    In the present study an attempt was made to generate cadastral base from high resolution satellite image (LISS IV) and to integrate with land use land cover information. The digital cadastral map with survey number for Kolathupalayam village in Erode district of Tamil Nadu was scanned, digitized and parcels were extracted. Similarly parcels or field boundaries were digitized and extracted from satellite image and were statistically compared by area. The area obtained from both the source through digitization correlated well with a pearson correlation of 0.87 and it was significant at 5 per cent. Thus, the area comparisons from both methods are significant indicating boundaries of individual fields generated from satellite image matched well with the one generated from cadastral map. The cadastral base generated from satellite image was overlaid on the classified image (level III output) to identify and generate land cover information against each survey number. Thus, the LISS IV data can be used for the identification and extraction of cadastral boundaries with good accuracy

    Spatial and temporal analysis of drought in Manjalar sub-basin of Vaigai in Tamil Nadu using standardized precipitation index

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    Drought is universally acknowledged as a phenomenon associated with scarcity of water. Drought characterization is essential for drought management operations. Using drought indices is a pragmatic way to assimilate large amounts of data into quantitative information that can be used in applications such as drought forecasting, declaring drought levels, contingency planning and impact assessment. Using monthly mean precipitation data for a period of 1982-2012 from 12 raingauge stations in the Manjalar sub-basin of Vaigai using Standardized Precipitation Index (SPI) is produced for the drought analysis with the time scale of 3 months (SPI-3), 6 months (SPI-6) and 12 months (SPI-12) as they are applicable for agriculture and hydrological aspects, respectively. It was observed that the basin experienced frequent droughts for all months of the year. The highest percentage of occurrence of drought was observed in the month of July (15.3), May (15.4) and August (15.6) at SPI-3, SPI-6 and SPI-12 respectively. On an average we observed 32.6, 8.6, 5.6 and 2.3 percentages of drought occurred by mild, moderate, severe and extreme drought respectively with respect to SPI-12. The results showed that mild droughts occur most frequently and extreme droughts occur least frequently and the basin suffered severe drought during the year of 1985, 2004 and 2006. The central and south eastern parts of the basin had more potential sensitivity to the droughts in comparison with the other areas of the basin

    Thermodynamic Investigation of a Modified Compression Ignition Engine Fueled by Diesel Biodiesel Ethanol Blends

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    The present study contrasts the thermodynamics analysis of modified diesel engines with traditional diesel engines. Thermodynamics study is done by the use of energy and exergy analysis for diesel, B20 (blend of 80 per cent diesel by volume with 20 per cent mahua biodiesel) and LHR modification and LTC 15 per cent EGR fuelled with B20 blend and 5 per cent ethanol with various loads ranging from no load to full load. Implemented two technologies for increasing engine efficiency. One of the primary techniques is the Low Heat Rejection (LHR) concept (or the so-called “Adiabatic” engine) applied. In the engine cylinder, a ceramic layer of Alumina (Al2O3) was used to modify the Low Heat Rejection (LHR). Another technique is Low-temperature combustion (LTC) modes are added by joining the inlet and exhaust pipes through valves to control the exhaust gas at an optimal rate of 15 per cent. The findings of energy and exergy distribution in the engine were compared using optimum alterations with fuel blends such as 20 per cent mahua biodiesel and 5 per cent ethanol. From energy distribution, best shaft power (QBP) (2.8kW) is transformed from heat input observed in the optimum altered engine at full load conditions compared to others. Due to modifications employed in the engine and fuels. Maximum unaccounted energy (QUN) loss in diesel (44 %). And highest thermal efficiency (31.2 %) is revealed in B20E5 (LHR+15 % LTC). From exergy distribution, it noticed that the same trend of energy distribution and at 100 per cent load condition, maximum (12.54kW) in diesel and minimum (8.45 kW) in B20E5 (LHR+15 % LTC) has obtained input availability (Ain).The maximum conversion rate of availability in brake power (Abp) (0.61 kW) in B20 (LHR). Compared to diesel, second law or exergetic efficiency more in B20E5 (LHR+15 % LTC).&nbsp

    Mapping of coconut growing areas in Tamil Nadu, India using remote sensing and GIS

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    Importance of remotely sensed data for inventorying, mapping, monitoring and for the management and development planning for the optimum utilization of natural resources has been well established. Though, a lot of applications have been attempted using remote sensing tool, mapping of coconut growing areas has not been attempted at a regional level. Hence, this study was envisaged to map the coconut growing areas in Tamil Nadu, India using Survey of India Toposheet grid (1:50,000 scale) and Digital Globe data. The temporal window of these datasets ranged from March 2012 to June 2014. The data sets have a spatial resolution of 41 cm. It has been observed that Coimbatore has largest area under coconut among all districts of Tamil Nadu, followed by Tiruppur, Thanjavur and Dindigul. In terms of percentage of coconut area to the total geographical area of the district, Tiruppur, leads the list, followed by Kanyakumari, Coimbatore and Thanjavur. On comparing the area obtained by this study with the area as per Coconut Development Board using a paired t-test, a p-value of 0.005 was obtained and hence, there is no significant difference between the two. Hence, it can be said that geospatial technologies like remote sensing and geographical information system are the best tools for accurate assessment and spatial data creation for crop mapping and area assessment

    Determination of metformin and triclosan in sewage sludge using Liquid chromatography-mass spectrometry (LC-MS)

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    Pharmaceuticals and personal care products (PPCPs) are generally neither totally removed by sewage treatment nor completely destroyed in the environment. Metformin (MET) and triclosan (TRI) are two compounds in PPCPs that have the potential to be environmental pollutants. This research aimed to determine MET and TRI in sewage sludge using a liquid chromatograph-mass spectrometer (LCMS-8040) and a sewage sludge extraction method. The Milli-Q water and sewage sludge were also tested at three different MET and TRI concentrations (0.01, 0.02, and 0.03 mg L-1). As a result, the corresponding recoveries of MET and TRI in both matrixes ranged from 85.93 to 116.10 per cent and 90.50 to 116.30 per cent (n = 7, RSD < 10%). Then, the limit of detection (LOD) and the limit of quantification (LOQ) for MET and TRI were found to be 0.005 and 0.01 mg L-1. The amounts of MET and TRI in the sewage sludge samples from the Ukkadam sewage treatment plant (USTP), Coimbatore, ranged from BDL to 0.0587 mg L-1 and 0.0719 to 0.1851 mg L-1, respectively. Consequently, the amounts of MET and TRI in the sewage sludge samples from the Tamil Nadu Agricultural University sewage treatment plant (TSTP), Coimbatore, ranged from BDL to 0.0227 mg L-1 and 0.0393 to 0.1296 mg L-1, respectively. This exclusive use of the highly sensitive LCMS-8040 consumes less time than other analytical methods for measuring the amount of MET and TRI in sewage sludge by overcoming the risk of chemical degradation

    Estimation of land surface temperature for Coimbatore District using Landsat imagery

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    The impact of climate change is visually witnessed in the present environment by various natural disasters. This phenomenon of land surface temperature is one of the significant aspects to be estimated for the study of climate change. The increase in Land Surface Temperature (LST) may be due to ongoing developments in the field of urbanization and globalization. The objective of the study was to estimate the increase in the LST in relation to the Normalized Difference Vegetation Index (NDVI) and assess the spatial variation in the LST due to land use/land cover change. The study utilized Landsat 8 data to assess the land-use changes and their relation with LST in one of the main urbanized cities, i.e.  Coimbatore district of Tamil Nadu, using Landsat imagery due to the availability of various land cover types by using the mathematical expressions in ARCMAP software. This study compares the LST between 2015 and 2020 to observe the change in the NDVI and LST over a period of 5 years in the Coimbatore district. There was an increase of 1°C in 5 years and the area of high LST had been increased comparatively. The maximum LST was found to be 73°C in 2015, which increased to 74°C in the year 2020 ;and the minimum LST was found to be 15°C in 2015, which increased to 19°C in the year 2020 depicting the ongoing change in the land use of the district. The study findings will help promulgate sustainable urban land-use policies and can be used for mitigating climate change
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