Digital Eprints Services at Vignan's Foundation for Science, Technology & Research
Not a member yet
721 research outputs found
Sort by
TEMPERATURE DEPENDENCE OF TISSUE THERMAL PARAMETERS SHOULD BE CONSIDERED IN THE THERMAL LESION PREDICTION IN HIGH-INTENSITY FOCUSED ULTRASOUND SURGERY
Get PDF—This study considers the temperature-dependent thermal parameters (specific heat capacity, thermal diffusivity and thermal conductivity) used when predicting the temperature rise of tissue exposed to high-intensity focused ultrasound (HIFU). Numerical analysis was performed using the equation coupled with a bioheat transfer function. The thermal parameters were set as the functions of temperature using experimental data. The results revealed that, for liver tissue exposed to HIFU with a focal intensity of 3000 W/cm2 for 10 s, the predicted focal temperature rise was 23% lower and the thermal lesion area 41% smaller than
those predicted without considering the temperature dependence. The prediction was validated by experimental observations on thermal lesions visualized in a tissue-mimicking phantom. The present results suggest that temperature dependent thermal parameters should be considered in the prediction of HIFU-induced temperature rise to avoid lowering ultrasonic output settings for HIFU surgery. The aim of the present study was to investigate how significantly the temperature dependence of the thermal parameters affects the thermal dose imposed on the tissue by a typical clinical HIFU device. A numerical simulation was performed using a thermo-acoustic algorithm coupling the non-linear hokhlov- Zabolotskaya-Kuznetsov (KZK) equation (Meaney et al. 1998; Filonenko and Khokhlova 2001) and a bioheat transfer (BHT) equation (Pennes 1948). Thermal parameters of liver tissue were modeled in the present study as functions of temperature and were incorporated into the BHT equation to compensate for the variations in thermal parameters with temperature. Experimental validation was achieved by comparing the predictions with the thermal lesions formed in the tissue-mimicking phantoms
End to end system for hazy image classification and reconstruction based on mean channel prior using deep learning network
Get PDFOutdoor images are having several applications including autonomous vehicles, geo-mapping, and surveillance. It is a common phenomenon that the images captured outdoor are prone to noise, which arises due to natural and manmade extreme atmospheric conditions such as haze, fog, and smog. Importantly in autonomous vehicle navigation, it is very important to recover the ground truth image to get the better decision by the system. Estimation of the transmission map and air-light is very crucial in recovering the ground truth image. In this study, the authors proposed a new method to estimate the transmission map based on a mean channel prior (MCP), which represents the depth map to estimate the transmission map. The authors proposed a deep neural network to identify the hazy image for the further dehazing process. In this study, the authors presented, two novel contributions, first an MCP-based image dehazing and second, a deep neural network-based identification of hazy images as a pre-processing block in the proposed end to end system. The proposed deep learning network using the TensorFlow platform provided validation accuracy of 93.4% for hazy image classification. Finally, the proposed MCP-based dehazing network showed better performance in terms of peak-signal-to-noise ratio, structural similarity index, and computational time than that of existing methods
Eco‑friendly fully bio‑based polybenzoxazine‑silica hybrid materials by sol–gel approach
Get PDFAbstract
In the present work, a high thermal and fame-retardant polybenzoxazine-silica hybrid material has been synthesized using renewable raw materials (including eugenol and furfurylamine) via a greener sol–gel-based approach. Inorganic com�ponent tetraethoxysilane (TEOS) was introduced into eugenol benzoxazine (BZ–E–F) with the help of (3-mercaptopropyl) trimethoxysilane (MPTMS) as a coupling
agent viz thiol-ene click approach among the mercapto group (–SH) of MPTMS and allyl functional group in the eugenol. The developed BZ–E–F monomer and PBZ–E–F hybrids are characterized to check the molecular structures, curing behaviour, thermal stability and fame-retardant properties. The thermal studies reveal that the char yield increases to 67.54 from 41.32 and LOI increased to 44.52 from 34.03
for PBZ–E–F silica hybrid. The thermal and fame-resistant studies strongly sug�gest that the prepared sustainable and eco-friendly PBZ silica hybrid can be used to replace the petroleum-based polymeric materials for better thermal and fame�resistant applications
"Rapid and ScalableWire-bar Strategy for Coating of TiO2 Thin-films: E ect of Post-Annealing Temperatures on Structures and Catalytic Dye-Degradation"
Get PDFThe use of teaching-learning based optimization technique for optimizing weld bead geometry as well as power consumption in additive manufacturing
No full textQuality of weld bead geometry (width and height of metal deposited) and power consumption are still big challenges to the manufacture to control them in gas metal arc based additive manufacturing. The present study is aimed to optimize weld bead geometry and also made an attempt to reduce power
consumption. Experiments are conducted at different torch angles, currents, wire feed speeds and welding speeds. Experimental results for width, height and depth of weld bead, power consumption and arc force are collected. Finite element method based numerical simulation is performed for width of
molten pool to study its effect on the width and height of the weld bead. The process parameters are optimized using teaching-learning based optimization technique for achieving optimum weld bead geometry and power consumption. The proposed methodology found two optimal working conditions.
Based on the power consumption, the optimal working condition-I is selected as best optimal working condition with optimum bead geometry such as 6.014 mm of width and 4.083 mm of height. The optimum power consumption is found to be 2496 W which is around 17%e41% less than that of experiments carried out. The optimal working condition is as follows: 124 A of current, 76.8 of torch angle, 8.38 m/min of wire feed speed and 0.42 m/min of welding speed
Surface development by reinforcing nano-composites during friction stir processing – a review
No full textPurpose – Friction stir processing (FSP) is overviewed with the process variables, along with the thermal aspect of different metals. Design/methodology/approach – With its inbuilt advantages, FSP is used to reduce the failure in the structural integrity of the body panels of automobiles, airplanes and lashing rails. FSP has excellent process ability and surface treatability with good corrosion resistance and high strength at elevated temperatures. Process parameters such as rotation speed of the tool, traverse speed, tool tilt angle, groove design, volume fraction and increase in number of tool passes should be considered for generating a processed and defect-free
surface of the workpiece. Findings – FSP process is used for modifying the surface by reinforcement of composites to improve the mechanical properties and results in the ultrafine grain refinement of microstructure. FSP uses the frictional
heat and mechanical deformation for achieving the maximum performance using the low-cost tool; the production time is also very les
An experimental assessment of prospective oxygenated additives on the diverse characteristics of diesel engine powered with waste tamarind biodiesel
No full textRapid depletion of petroleum resources, surge in fuel prices and stringent emission norms play a key role on economic development of a country like India in terms of energy efficiency, which attracts the researchers to search for novel alternative fuel for diesel. The work reported here focuses on the effect of various oxygenated additives such as diethyl ether, dimethyl ether and dimethyl carbonate to 20% tamarind seed methyl ester (TSME 20) biodiesel blend of different concentrations (6% and 12%) on volume basis to examine engine characteristics. The test results revealed that 12% diethyl ether added TSME20 is shown considerable enhancement in brake thermal efficiency, which is 4.22% higher over
tamarind biodiesel blend. Similarly, TSME20 DEE 12 has shown significant reductions in harmful engine tailpipe emissions such as carbon monoxide, hydrocarbon, oxides of nitrogen and smoke opacity which are noted to be about 10.68%, 33.33%, 10.33% and 27.72% respectively when compared to diesel fuel at full load. Further, the DIESEL-RK theoretical simulation results are compared with the experimental values, conducted at the same operating conditions and it is inferred that 12% diethyl ether addition to TSME 20 has shown promising engine characteristics both experimentally and theoreticall
Characterization of novel composites from polybenzoxazine and granite powder
No full textThe potential of using granite dust as reinforcement into polybenzoxazine matrix was investigated. In this article, novel
granite powder waste-reinforced bisphenol-A aniline-based benzoxazine composites were prepared using solution
blending technique by varying the content of granite powder from 10 to 40 wt%. The efect of the granite powder
content on the thermal, structural, dimensional, and morphological properties of granite powder/polybenzoxazine
composites have been investigated. Thermogravimetric analysis (TGA) was performed on the composite samples. Char
yield of the composites increased from 44.55 to 67.70% for increasing fller content from 10 to 40wt%, whereas 22%
for pure polybenzoxazine. The maximum weight loss temperatures of the composites were analyzed from derivative of thermogravimetric analysis (DTG). Limiting oxygen index (LOI) values also increased as granite powder content increased.
Structural properties of benzoxazine, polybenzoxazine, and composites were observed with Fourier-transform infrared
spectroscopy (FTIR). Dimensional stability of the composites was investigated through the water absorption test up to
30 days. The composites exhibited zero percent water absorption. Micro-hardness of the composites increased from
17.45 to 78.66% for increasing fller content from 10–40 wt% when compared with pristine polybenzoxazine. The mor�phological analysis using scanning electron microscopy (SEM) showed the distribution of fller, aggregate formation,
compatibility between polybenzoxazine and granite powder. Overall, the importance of using granite powder waste as
reinforcement in polybenzoxazine composites revealed from results of the structural, dimensional, and morphological
analysis along with the improvement in thermal properties and micro-hardnes
CFD Studies Of Mixing Behavior Of Inert Sand With Biomass In Fluidized Bed
No full textAgriculture deposits, which remains unused and often causes ecological problems, could play an important role as an energy source to meet energy needs in developing countries ' rural areas. Moreover, energy levels in these deposits are low
and need to be elevated by introducing efficient operative conversion technologies to utilize these residues as fuels. In this context, the utilization of a fluidized bed innovation enables a wide range of non-uniform-sized low-grade fuels to be
effectively converted into other forms of energy. This study was undertaken to evaluate the effectiveness of fluidized conversion method for transformation of agricultural by-products such as rice husk, sawdust, and groundnut shells into useful
energy. The present investigation was conducted to know the mixing characteristics of sand and fuel have been found by conducting experiments with mixing ratio of rice
husk (1:13), saw dust(1:5) and groundnut shells (1:12), the variation of particle movement in the bed and mixing characteristics are analyzed. The impact of sand molecule size on the fluidization speed of two biofuel and sand components is studied and recommended for groundnut shells using a sand molecule of 0.6 mm size and for rice husk, sawdust 0.4 mm sand particle size. Also, establish that the particle size of sand has a significant effect on mingling features in case of sawdust. In the next part of the investigation, the CFD simulations of the fluidized bed are done to investigate the mixing behavior of sand and biomass particles. A set of simulations are conducted by ANSYS FLUENT 16; the state of the bed is the same as that of the test. The findings were presented with the volume fraction of sand and biomass particles in the form of contour plots
Multi Objective Optimization Of Fsw Process Parameters Using Genetic Algorithm And Tlbo Algorithm
No full textAA2014 has been extensively used in manufacture of light weight fabricated
components similar to commercial automobile components, which requires high strength with minimal weight and along with decent corrosion effect. The traditional welding of this Aluminium alloyed materials generally encounter solidification
problems like hot cracking. Friction Stir Welding (FSW) is an ecofriendly joining process where in the actual melting of material and recasting will not happen. Many of the researchers carried out sufficient experiments for optimizing process
parameters and to establish empirical relationships in order to predict better mechanical properties. In the present investigation, a comparative study of FSW between experimentation and optimization of process parameters such as tool rotation speed and weld speed, to attain maximum mechanical properties using Genetic Algorithm (GA) and Teaching Learning Based Optimization (TLBO) algorithm.
From the results it shows that the TLBO gives the better combinations of process parameters which give superior mechanical properties compared to experimental results as well as other optimization techniques