Aditya Chauhan QC - Academia.edu (original) (raw)

Papers by Aditya Chauhan QC

Materials Today: Proceedings

Abstract Stealth aircraft use Stealth Technology in order to evade recognition by utilizing mix o... more Abstract Stealth aircraft use Stealth Technology in order to evade recognition by utilizing mix of highlights with the goal that Aircraft can invade with RADAR and furthermore decrease the deceivability in “radio frequency (RF) range”, sound and infrared visual. During the most recent decades, stealth technology has demonstrated to be one of the best methodologies to the extent the undertaking to escape radar systems is concerned. Stealth intends to evade the recognition or attempt to cover up, for planes, avoiding radar implied stealth. The idea utilized in the stealth innovation isn’t so difficult. It utilizes the guideline to retain and mirror the radar waves. Airplane redirects the radar waves in different ways and limits the radar waves which return back to radar. Another marvel which permits the air ship maintain completely the incoming radar wavelengths to inhabit the electromagnetic reincorporated energy in various way. The structure and material used to manufacture air ship choose the degree of stealth accomplish via air ship. The thought for the radar radio wire to release Radio energy that is then returned through any item that occurs to recognize. The time taken for the reflection to come is measure by the radar radio wire and it can tell how far off an object is.

Cells

Non-alcoholic steatohepatitis (NASH) is a chronic and progressive form of non-alcoholic fatty liv... more Non-alcoholic steatohepatitis (NASH) is a chronic and progressive form of non-alcoholic fatty liver disease. Its global incidence is increasing and makes NASH an epidemic and a public health threat. Non-alcoholic fatty liver disease is associated with major morbidity and mortality, with a heavy burden on quality of life and liver transplant requirements. Due to repeated insults to the liver, patients are at risk for developing hepatocellular carcinoma. The progression of NASH was initially defined according to a two-hit model involving an initial development of steatosis, followed by a process of lipid peroxidation and inflammation. In contrast, current evidence proposes a “multi-hit” or “multi-parallel hit” model that includes multiple pathways promoting progressive fibrosis and oncogenesis. This model includes multiple cellular, genetic, immunological, metabolic, and endocrine pathways leading to hepatocellular carcinoma development, underscoring the complexity of this disease.

I would like to acknowledge the support received from the Cambridge Trust and the Science and Eng... more I would like to acknowledge the support received from the Cambridge Trust and the Science and Engineering Research Board (SERB), New Delhi in the form of Cambridge India Ramanujan scholarship.

Journal of Cleaner Production

ABSTRACT The growing demand for energy over the last few decades has increased our dependency on ... more ABSTRACT The growing demand for energy over the last few decades has increased our dependency on fossil fuel-based sources leading to significant environmental degradation and huge external debt. This article addresses the wide spectrum role of some well-planned decentralised-distributed energy networks to realize the need for comprehensive energy planning for inclusive economic growth. An extensive review of different design configurations, their implementation models and socio-economic dimensions are critically presented with solutions for clean energy deliverance. The article recommends that the objectives of uniform energy regulation and its wide range distribution should be based on some novel anticipated models, sufficient enough to fulfil energy demand and to integrate some other energy sources at minimum possible cost for a particular site. The constraints have been well identified at modelling, budgetary and implementation stages as required for uninterrupted and uniform distribution specifically to the far-reaching areas. This study has also resulted in the establishment of the statement that “Technological advancements with specific solutions coordinated through central monitoring are essential because of the fast and reliable implementation of the plan on-ground”. It is also notable that, Role of different and individual stakeholders should be fixed to take an integral part in the advantageous use of decentralized energy network by analysing and utilizing locally available resources.

Journal of Thermal Analysis and Calorimetry

This article evaluates and compares the enviro-economic potential of two distinctly (parallel flo... more This article evaluates and compares the enviro-economic potential of two distinctly (parallel flow and serpentine flow) fabricated PV/T water heating systems in view of their respective thermal optimization. A one-dimensional steady-state heat transfer model along with the concept of least entropy production yields around 20 lh−1 being the optimal flow which corresponds to highest thermal exergy of 1.5 and 1.8% for the two systems under consideration. The modeling results reveal an appreciable validation with the experimental data which correspond to maximum increment in DC power by 17.7 and 19.3 W complimented by their low-grade water heating applications worth 493.5 and 530.8 W, respectively. The mitigation potential of both the systems is well appreciated through certain pre-defined parameters as an outcome of the economic modeling. An additional 35–40% increment in total efficiency corresponds to almost 7–8% gain in electrical power with respective (parallel and serpentine) thermal configurations. Both the systems unanimously contribute 15 and 18% increment in their respective exergy-based mitigation potential as compared against 85 and 97% increment in energy-based enviro-economic parameter with respect to solo PV installation. Exergy-based performance indices show smaller increment with respect to energy-based EPI for both the designs, while energy payback period of the serpentine-based thermal installation falls 3 years shorter than a standard 255-W reference PV module.

Materials Research Bulletin

Abstract Piezocatalysis is defined as the catalytic activity displayed by piezoelectric materials... more Abstract Piezocatalysis is defined as the catalytic activity displayed by piezoelectric materials in the presence of suitable (mechanical excitation). Through this phenomenon, harvested electric energy can be directly utilized for environment remediation. This article reports on the development and application of piezoelectric composites for achieving water-treatment under dark-conditions. Cement composites containing (10, 20, and 30 wt%) BaTiO3 were fabricated and tested for removal of various textile dyes and pharmaceutical compounds from wastewater. The catalytic activity was observed to be dependent on both the loading concentration and excitation amplitude, with electrically poled samples (containing 30 wt% BaTiO3) displaying a maximum piezoelectric coefficient of ≈29 pC/N. Pollutant removal was achieved using ultrasonication as excitation source. These prepared composites also displayed a high stability against mechanical degradation under repeated usage. The presented results provide a new approach for development of functional cements for practical active and passive environmental remediation.

Solar Energy

Abstract This particular research article is an attempt to unify two distinct classical theories ... more Abstract This particular research article is an attempt to unify two distinct classical theories i.e. (i)-principle of minimum entropy generation (MEG) and (ii)-Hottel Whillier (HW) model in view of thermal optimization of PV/T and FPC collectors. Solar conversion systems are highly susceptible to substantial exergy losses in particular to thermal exergy, hence it would be better to have some sort of generalized approach, which in this paper was put forward in the form of irreversibility. The entire canvass of the paper focuses to show that how the elementary concepts in thermodynamics can be validated against a heat transfer problem to yield almost similar results. Based on MEG principle and its HW validation it has been investigated that certain minimum amount of entropy generation is the necessary criterion in order to anticipate maximum exergetic values particularly associated with heat interactions. The optimized mass flow rates for PV/T and FPC using MEG and HW models were respectively found to be 17 & 20 l / h PV / T and 8 & 10 l / h FPC . However, the conclusive difference in the two approaches comes from the fact that MEG model take care of the universal entropy generation optimization, while HW model was system specific only. The transition in diameter which occurs towards asymptotic minimum entropy generation per unit length was found to be at 0.00875 m and 0.01 m for the two collectors particularly associated with laminar flow and constant heat flux source. The maximum temperature of the modeled PV module (255Wp) was ideally predicted to be reduce by 18 °C through the proposed design which corresponds to 8.6% increment in the electrical efficiency. A parameter χ based on useful thermal gain per unit cost of thermal management was maximized in order to optimize the center to center tube spacing.

Energy

Abstract This experimental investigation aimed to depict the effects of varying loads at various ... more Abstract This experimental investigation aimed to depict the effects of varying loads at various compression ratios with thumba methyl esters in different proportions as fuel on a variable compression ratio diesel engine. Series of tests were conducted on a single cylinder, 3.6 kW, water cooled, variable compression ratio, stationary diesel engine, as per the full factorial design to measure the performance and emission characteristics. The engine load, compression ratio and blending ratio for citrullus colocynthis (thumba oil) based diesel were taken as input parameters and their effects on engine performance and emissions characteristics such as BTE, BSFC, HC, NOx & CO were investigated experimentally and analytically. Experimental data was analysed and modelled using the full factorial design in three different stages to achieve the optimum results for performance and emission characteristics. For each stage, second order and third order estimate models were developed and were checked for assumptions of Analysis of Variance i.e. normality & homogeneity of data. The optimum performance & emission characteristics were observed with 20% thumba-diesel blend, at a compression ratio of 18 at maximum load. It was found that the optimum values of BSFC, BTE, HC, CO & NOx was 0.456 kg/kWh, 19.725%, 38.432 ppm, 0.026% and 348.744 ppm respectively at load of 10 kg, CR of 18, and blend percentage of 20. A good agreement between experimental results and predication results depicts that the developed models can be used with competence to optimize similar type diesel engine parameters using citrullus colocynthis (thumba oil) blend without engine modification.

Scientific Reports

this article aims to propose a cantilever based cooling device employing non-axis symmetric place... more this article aims to propose a cantilever based cooling device employing non-axis symmetric placement of bulk ferroelectric patches. Ambient mechanical vibrations produce large stresses in cantilevers resulting in elastocaloric effect associated with ferroelectrics. Further, design allows cascading of several cantilevers to achieve large cooling response. A finite element analysis of the system was performed using material properties of bulk 0.50Ba(Zr 0.2 ti 0.8)o 3 −0.50(Ba 0.7 Ca 0.3)tio 3. An individual element could produce a peak elastocaloric effect of 0.02 K (324 K); whereas the proposed system could achieve a temperature drop of 0.2 K within 50 seconds (10 elements, 1.5 Hz). Furthermore, net cooling can be further improved about ~2 K (using 10 cantilevers) for a starting temperature of 358 K. This study shows that elastocaloric effect in ferroelectric materials is capable of converting waste mechanical vibration into refrigeration effect which is not reported so far.

Journal of Industrial and Engineering Chemistry

To secure reliable alternative energy sources, the up-conversion of solar energy into storable ch... more To secure reliable alternative energy sources, the up-conversion of solar energy into storable chemical energy holds promise. This review is organized to highlight recent advances in the fields of solar energy utilization and conversion methods with the aid of various heterogeneous catalysts. Special emphasis has been placed on TiO 2 photoanode catalysts, band-gap engineering, TiO 2-coupled light-harvesting molecules, and photon-coupled electron transfer via electron transport mediator systems. Furthermore, the coverage of this review extends to the topics of oxygen evolution catalysts, water reduction catalysts, and a system assembly capable of completing the four-electron water-oxidation reaction for efficient photocatalytic water splitting.

Materials Today Communications

Abstract A facile method is proposed for the in-situ synthesis of titania-carbon (TiO2-C) core-sh... more Abstract A facile method is proposed for the in-situ synthesis of titania-carbon (TiO2-C) core-shell composite structures with ameliorated photocatalytic properties. The particles were prepared by controlled hydrolysis of titanium alkoxides followed by calcination in a non-oxygenating atmosphere. To study the effect of fabrication technique on the size and morphology of the prepared catalyst, three different combinations of precursors and solvents were investigated. Phase purity, physical and chemical characterization of the as-synthesized catalysts were confirmed using X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy and Raman spectroscopy techniques. Photocatalytic activity of the catalyst was evaluated by monitoring mineralization of methylene blue dye solution under solar illumination. It was observed that compared to standard titania, samples containing carbon were up to eight times more efficient at achieving solar assisted mineralization of dye. Subsequent analysis revealed that choice of titanium alkoxide and solvent (alcohol) can significantly affect the crystallite size, color and surface area of the calcined samples. The enhanced photocatalytic activity of the TiO2-C catalysts can be attributed to improved visible light absorption and a larger surface area.

Energy Technology

When employed appropriately, ferroelectric materials present themselves as one of the most effici... more When employed appropriately, ferroelectric materials present themselves as one of the most efficient means of waste (thermal/mechanical) energy scavenging. A large conversion potential can be obtained when appropriate materials are combined with high-field actuation (Ericsson cycle). However, waste energy rarely presents itself in an isolated form (heat or vibration). There is also a distinct lack of systems capable of simultaneous thermomechanical energy conversion, especially in the low-frequency range. In this regard a systematic approach to the concept of combined energy harvesting and storage potential of a singular material system is presented. Polarization versus electric field hysteresis loops were gathered as a function of temperature, uniaxial compressive stress, and electric field. Thereafter, a theoretical assessment was made to the effect of the biased and unbiased energy conversion potential of 0.50Ba(Zr0.2Ti0.8)O3– 0.50(Ba0.7Ca0.3)TiO3 bulk lead-free ferroelectric material. Maximum energy conversion potentials of 150 and 210 kJm@3 were obtained for thermal (5 MPa, 24–96 8C) and mechanical cycles (24 8C, 5–160 MPa), respectively. A slightly improved performance of 220 kJm@3 was obtained under simultaneous depolarization, despite performance degradation through individual biasing. However, the energy-storage density improved by 100% (80 kJm@3) and 50% (60 kJm@3), respectively, when operated under elevated stress (60 MPa) and temperature (90 8C). Results are indicative of a singular material system that could be used for combined thermomechanical energy conversion and on-board storage capacity.

Asian Journal of Management

Stress is a psychologic and physiologic imbalance resulting from adverse circumstances. College i... more Stress is a psychologic and physiologic imbalance resulting from adverse circumstances. College is probably a best phase of life for students. These crucial years can be undermined by stress and depression. Students are likely to experience stress due to heavy syllabus, new environment, new friends and dealing with myriad of various issues. They also encounter a number of challenges in their life, therefore their whole college life is unveiled by challenges which in turn causes stress and if not dealt with, can hamper their academic performance. The purpose of this paper is to find out the causes of stress among graduate college students. The present study consists of 100 graduate students of Ludhiana. Data was collected through questionnaire which was randomly distributed among college students. The present study reveals that Competition is the biggest reason for stress but others reasons such as family pressure, placement and academics also are major stress inducers. It is concluded that many of the respondents feel it comfortable to talk to their friends or family in case to overcome stress.

Journal of the American Ceramic Society

Ferroelectric materials are being actively explored for next-generation solid-state cooling techn... more Ferroelectric materials are being actively explored for next-generation solid-state cooling technology. Even though bulk materials possess an advantage in terms of overall heat extraction capacity, their performance is limited due to low adiabatic temperature change. In this regard, the present article explores enhanced cooling capacity of bulk polycrystalline Pb0.99Nb0.02(Zr0.95Ti0.05)0.08O3 (PNZT) through external-field mediation and coupled caloric effects. Barocaloric (BC) and electrocaloric (EC) effects were indirectly estimated using polarization versus electric field (P-E) loops (under varying pressure and temperature). It was observed that under applied pressure of 325 MPa, ∆TEC could be improved from 1 K to 4.5 K. Similarly, a peak unbiased ∆TBC of 1.5 K could be enhanced to 5.3 K under an electric field of 5 MV.m−1. These figures correspond to an improvement of ~400% over the unbiased values. The results are indicative of the potential of multicaloric cooling capacity of bulk ferroelectric materials. This article is protected by copyright. All rights reserved.

Applied Physics Letters, 2016

Microcrystals of LiNbO3 (size ∼200 nm) can be selectively precipitated in a glass matrix which ca... more Microcrystals of LiNbO3 (size ∼200 nm) can be selectively precipitated in a glass matrix which can assist in the photocatalytic activity through ferroelectricity. Glass with the composition 30SiO2-35Li2CO3-35Nb2O5 was utilized for the process. A remarkably high Estriol (E3) degradation rate of 232.54 min−1 m−2 was obtained. The degradation was monitored using fluorescence spectroscopy with a detection limit in nanomolar (nM) range. From the fitting of fluorescence intensity versus time, it was observed that degradation of estriol follows a pseudo first-order reaction kinetics. The results indicate that LiNbO3 based glass-ceramics have a great potential to be employed as a well embedded photocatalyst.

Applied Physics Letters, 2016

Polyvinylidene di-fluoride-based polymers were investigated for elastocaloric and barocaloric eff... more Polyvinylidene di-fluoride-based polymers were investigated for elastocaloric and barocaloric effects. Bulk samples were subjected to uniaxial tensile and hydrostatic loading. Resulting strain profile (function of temperature) was used to predict the temperature change. A peak elastocaloric effect of 1.8 K was observed at 298 K (15 MPa). Alternately, a large barocaloric effect of ∼6 K was observed at 300 K (200 MPa). This was further improved to an astounding ∼19 K near 368 K (200 MPa). The results of this study are expected to greatly benefit the field of ferroelectric solid-state refrigeration and open another horizon for future exploration of multicaloric effects in ferroelectric polymers.

Phase Transitions, 2015

Development of a practical electrocaloric (EC) refrigeration system is hindered by four main draw... more Development of a practical electrocaloric (EC) refrigeration system is hindered by four main drawbacks: (a) low adiabatic temperature change near room temperature, (b) requirement of large electric field to achieve desirable temperature change, (c) low isothermal entropy change and (d) low thermal capacity. Here, we demonstrate that replacing Ca by Sr in the bulk ceramics of nominal composition Ba0.85Ca0.15-xSrxTi0.9Zr0.1O3, can address these shortcomings. Evidently, a large of 2.4 K can be obtained near room temperature (303 K) at relatively low electric field (37 kV.cm−1). These numbers indicate an EC performance that exceeds most bulk materials, surpassing even those reported for advanced thin-film composites. Further, a comparative analysis of the EC strength against reveals that the Sr modified composition is the optimum material, for EC cooling applications.

Materials, 2015

With an ever increasing dependence on electrical energy for powering modern equipment and electro... more With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE) display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

Applied Physics Letters, 2015

Materials Today: Proceedings

Abstract Stealth aircraft use Stealth Technology in order to evade recognition by utilizing mix o... more Abstract Stealth aircraft use Stealth Technology in order to evade recognition by utilizing mix of highlights with the goal that Aircraft can invade with RADAR and furthermore decrease the deceivability in “radio frequency (RF) range”, sound and infrared visual. During the most recent decades, stealth technology has demonstrated to be one of the best methodologies to the extent the undertaking to escape radar systems is concerned. Stealth intends to evade the recognition or attempt to cover up, for planes, avoiding radar implied stealth. The idea utilized in the stealth innovation isn’t so difficult. It utilizes the guideline to retain and mirror the radar waves. Airplane redirects the radar waves in different ways and limits the radar waves which return back to radar. Another marvel which permits the air ship maintain completely the incoming radar wavelengths to inhabit the electromagnetic reincorporated energy in various way. The structure and material used to manufacture air ship choose the degree of stealth accomplish via air ship. The thought for the radar radio wire to release Radio energy that is then returned through any item that occurs to recognize. The time taken for the reflection to come is measure by the radar radio wire and it can tell how far off an object is.

Cells

Non-alcoholic steatohepatitis (NASH) is a chronic and progressive form of non-alcoholic fatty liv... more Non-alcoholic steatohepatitis (NASH) is a chronic and progressive form of non-alcoholic fatty liver disease. Its global incidence is increasing and makes NASH an epidemic and a public health threat. Non-alcoholic fatty liver disease is associated with major morbidity and mortality, with a heavy burden on quality of life and liver transplant requirements. Due to repeated insults to the liver, patients are at risk for developing hepatocellular carcinoma. The progression of NASH was initially defined according to a two-hit model involving an initial development of steatosis, followed by a process of lipid peroxidation and inflammation. In contrast, current evidence proposes a “multi-hit” or “multi-parallel hit” model that includes multiple pathways promoting progressive fibrosis and oncogenesis. This model includes multiple cellular, genetic, immunological, metabolic, and endocrine pathways leading to hepatocellular carcinoma development, underscoring the complexity of this disease.

I would like to acknowledge the support received from the Cambridge Trust and the Science and Eng... more I would like to acknowledge the support received from the Cambridge Trust and the Science and Engineering Research Board (SERB), New Delhi in the form of Cambridge India Ramanujan scholarship.

Journal of Cleaner Production

ABSTRACT The growing demand for energy over the last few decades has increased our dependency on ... more ABSTRACT The growing demand for energy over the last few decades has increased our dependency on fossil fuel-based sources leading to significant environmental degradation and huge external debt. This article addresses the wide spectrum role of some well-planned decentralised-distributed energy networks to realize the need for comprehensive energy planning for inclusive economic growth. An extensive review of different design configurations, their implementation models and socio-economic dimensions are critically presented with solutions for clean energy deliverance. The article recommends that the objectives of uniform energy regulation and its wide range distribution should be based on some novel anticipated models, sufficient enough to fulfil energy demand and to integrate some other energy sources at minimum possible cost for a particular site. The constraints have been well identified at modelling, budgetary and implementation stages as required for uninterrupted and uniform distribution specifically to the far-reaching areas. This study has also resulted in the establishment of the statement that “Technological advancements with specific solutions coordinated through central monitoring are essential because of the fast and reliable implementation of the plan on-ground”. It is also notable that, Role of different and individual stakeholders should be fixed to take an integral part in the advantageous use of decentralized energy network by analysing and utilizing locally available resources.

Journal of Thermal Analysis and Calorimetry

This article evaluates and compares the enviro-economic potential of two distinctly (parallel flo... more This article evaluates and compares the enviro-economic potential of two distinctly (parallel flow and serpentine flow) fabricated PV/T water heating systems in view of their respective thermal optimization. A one-dimensional steady-state heat transfer model along with the concept of least entropy production yields around 20 lh−1 being the optimal flow which corresponds to highest thermal exergy of 1.5 and 1.8% for the two systems under consideration. The modeling results reveal an appreciable validation with the experimental data which correspond to maximum increment in DC power by 17.7 and 19.3 W complimented by their low-grade water heating applications worth 493.5 and 530.8 W, respectively. The mitigation potential of both the systems is well appreciated through certain pre-defined parameters as an outcome of the economic modeling. An additional 35–40% increment in total efficiency corresponds to almost 7–8% gain in electrical power with respective (parallel and serpentine) thermal configurations. Both the systems unanimously contribute 15 and 18% increment in their respective exergy-based mitigation potential as compared against 85 and 97% increment in energy-based enviro-economic parameter with respect to solo PV installation. Exergy-based performance indices show smaller increment with respect to energy-based EPI for both the designs, while energy payback period of the serpentine-based thermal installation falls 3 years shorter than a standard 255-W reference PV module.

Materials Research Bulletin

Abstract Piezocatalysis is defined as the catalytic activity displayed by piezoelectric materials... more Abstract Piezocatalysis is defined as the catalytic activity displayed by piezoelectric materials in the presence of suitable (mechanical excitation). Through this phenomenon, harvested electric energy can be directly utilized for environment remediation. This article reports on the development and application of piezoelectric composites for achieving water-treatment under dark-conditions. Cement composites containing (10, 20, and 30 wt%) BaTiO3 were fabricated and tested for removal of various textile dyes and pharmaceutical compounds from wastewater. The catalytic activity was observed to be dependent on both the loading concentration and excitation amplitude, with electrically poled samples (containing 30 wt% BaTiO3) displaying a maximum piezoelectric coefficient of ≈29 pC/N. Pollutant removal was achieved using ultrasonication as excitation source. These prepared composites also displayed a high stability against mechanical degradation under repeated usage. The presented results provide a new approach for development of functional cements for practical active and passive environmental remediation.

Solar Energy

Abstract This particular research article is an attempt to unify two distinct classical theories ... more Abstract This particular research article is an attempt to unify two distinct classical theories i.e. (i)-principle of minimum entropy generation (MEG) and (ii)-Hottel Whillier (HW) model in view of thermal optimization of PV/T and FPC collectors. Solar conversion systems are highly susceptible to substantial exergy losses in particular to thermal exergy, hence it would be better to have some sort of generalized approach, which in this paper was put forward in the form of irreversibility. The entire canvass of the paper focuses to show that how the elementary concepts in thermodynamics can be validated against a heat transfer problem to yield almost similar results. Based on MEG principle and its HW validation it has been investigated that certain minimum amount of entropy generation is the necessary criterion in order to anticipate maximum exergetic values particularly associated with heat interactions. The optimized mass flow rates for PV/T and FPC using MEG and HW models were respectively found to be 17 & 20 l / h PV / T and 8 & 10 l / h FPC . However, the conclusive difference in the two approaches comes from the fact that MEG model take care of the universal entropy generation optimization, while HW model was system specific only. The transition in diameter which occurs towards asymptotic minimum entropy generation per unit length was found to be at 0.00875 m and 0.01 m for the two collectors particularly associated with laminar flow and constant heat flux source. The maximum temperature of the modeled PV module (255Wp) was ideally predicted to be reduce by 18 °C through the proposed design which corresponds to 8.6% increment in the electrical efficiency. A parameter χ based on useful thermal gain per unit cost of thermal management was maximized in order to optimize the center to center tube spacing.

Energy

Abstract This experimental investigation aimed to depict the effects of varying loads at various ... more Abstract This experimental investigation aimed to depict the effects of varying loads at various compression ratios with thumba methyl esters in different proportions as fuel on a variable compression ratio diesel engine. Series of tests were conducted on a single cylinder, 3.6 kW, water cooled, variable compression ratio, stationary diesel engine, as per the full factorial design to measure the performance and emission characteristics. The engine load, compression ratio and blending ratio for citrullus colocynthis (thumba oil) based diesel were taken as input parameters and their effects on engine performance and emissions characteristics such as BTE, BSFC, HC, NOx & CO were investigated experimentally and analytically. Experimental data was analysed and modelled using the full factorial design in three different stages to achieve the optimum results for performance and emission characteristics. For each stage, second order and third order estimate models were developed and were checked for assumptions of Analysis of Variance i.e. normality & homogeneity of data. The optimum performance & emission characteristics were observed with 20% thumba-diesel blend, at a compression ratio of 18 at maximum load. It was found that the optimum values of BSFC, BTE, HC, CO & NOx was 0.456 kg/kWh, 19.725%, 38.432 ppm, 0.026% and 348.744 ppm respectively at load of 10 kg, CR of 18, and blend percentage of 20. A good agreement between experimental results and predication results depicts that the developed models can be used with competence to optimize similar type diesel engine parameters using citrullus colocynthis (thumba oil) blend without engine modification.

Scientific Reports

this article aims to propose a cantilever based cooling device employing non-axis symmetric place... more this article aims to propose a cantilever based cooling device employing non-axis symmetric placement of bulk ferroelectric patches. Ambient mechanical vibrations produce large stresses in cantilevers resulting in elastocaloric effect associated with ferroelectrics. Further, design allows cascading of several cantilevers to achieve large cooling response. A finite element analysis of the system was performed using material properties of bulk 0.50Ba(Zr 0.2 ti 0.8)o 3 −0.50(Ba 0.7 Ca 0.3)tio 3. An individual element could produce a peak elastocaloric effect of 0.02 K (324 K); whereas the proposed system could achieve a temperature drop of 0.2 K within 50 seconds (10 elements, 1.5 Hz). Furthermore, net cooling can be further improved about ~2 K (using 10 cantilevers) for a starting temperature of 358 K. This study shows that elastocaloric effect in ferroelectric materials is capable of converting waste mechanical vibration into refrigeration effect which is not reported so far.

Journal of Industrial and Engineering Chemistry

To secure reliable alternative energy sources, the up-conversion of solar energy into storable ch... more To secure reliable alternative energy sources, the up-conversion of solar energy into storable chemical energy holds promise. This review is organized to highlight recent advances in the fields of solar energy utilization and conversion methods with the aid of various heterogeneous catalysts. Special emphasis has been placed on TiO 2 photoanode catalysts, band-gap engineering, TiO 2-coupled light-harvesting molecules, and photon-coupled electron transfer via electron transport mediator systems. Furthermore, the coverage of this review extends to the topics of oxygen evolution catalysts, water reduction catalysts, and a system assembly capable of completing the four-electron water-oxidation reaction for efficient photocatalytic water splitting.

Materials Today Communications

Abstract A facile method is proposed for the in-situ synthesis of titania-carbon (TiO2-C) core-sh... more Abstract A facile method is proposed for the in-situ synthesis of titania-carbon (TiO2-C) core-shell composite structures with ameliorated photocatalytic properties. The particles were prepared by controlled hydrolysis of titanium alkoxides followed by calcination in a non-oxygenating atmosphere. To study the effect of fabrication technique on the size and morphology of the prepared catalyst, three different combinations of precursors and solvents were investigated. Phase purity, physical and chemical characterization of the as-synthesized catalysts were confirmed using X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy and Raman spectroscopy techniques. Photocatalytic activity of the catalyst was evaluated by monitoring mineralization of methylene blue dye solution under solar illumination. It was observed that compared to standard titania, samples containing carbon were up to eight times more efficient at achieving solar assisted mineralization of dye. Subsequent analysis revealed that choice of titanium alkoxide and solvent (alcohol) can significantly affect the crystallite size, color and surface area of the calcined samples. The enhanced photocatalytic activity of the TiO2-C catalysts can be attributed to improved visible light absorption and a larger surface area.

Energy Technology

When employed appropriately, ferroelectric materials present themselves as one of the most effici... more When employed appropriately, ferroelectric materials present themselves as one of the most efficient means of waste (thermal/mechanical) energy scavenging. A large conversion potential can be obtained when appropriate materials are combined with high-field actuation (Ericsson cycle). However, waste energy rarely presents itself in an isolated form (heat or vibration). There is also a distinct lack of systems capable of simultaneous thermomechanical energy conversion, especially in the low-frequency range. In this regard a systematic approach to the concept of combined energy harvesting and storage potential of a singular material system is presented. Polarization versus electric field hysteresis loops were gathered as a function of temperature, uniaxial compressive stress, and electric field. Thereafter, a theoretical assessment was made to the effect of the biased and unbiased energy conversion potential of 0.50Ba(Zr0.2Ti0.8)O3– 0.50(Ba0.7Ca0.3)TiO3 bulk lead-free ferroelectric material. Maximum energy conversion potentials of 150 and 210 kJm@3 were obtained for thermal (5 MPa, 24–96 8C) and mechanical cycles (24 8C, 5–160 MPa), respectively. A slightly improved performance of 220 kJm@3 was obtained under simultaneous depolarization, despite performance degradation through individual biasing. However, the energy-storage density improved by 100% (80 kJm@3) and 50% (60 kJm@3), respectively, when operated under elevated stress (60 MPa) and temperature (90 8C). Results are indicative of a singular material system that could be used for combined thermomechanical energy conversion and on-board storage capacity.

Asian Journal of Management

Stress is a psychologic and physiologic imbalance resulting from adverse circumstances. College i... more Stress is a psychologic and physiologic imbalance resulting from adverse circumstances. College is probably a best phase of life for students. These crucial years can be undermined by stress and depression. Students are likely to experience stress due to heavy syllabus, new environment, new friends and dealing with myriad of various issues. They also encounter a number of challenges in their life, therefore their whole college life is unveiled by challenges which in turn causes stress and if not dealt with, can hamper their academic performance. The purpose of this paper is to find out the causes of stress among graduate college students. The present study consists of 100 graduate students of Ludhiana. Data was collected through questionnaire which was randomly distributed among college students. The present study reveals that Competition is the biggest reason for stress but others reasons such as family pressure, placement and academics also are major stress inducers. It is concluded that many of the respondents feel it comfortable to talk to their friends or family in case to overcome stress.

Journal of the American Ceramic Society

Ferroelectric materials are being actively explored for next-generation solid-state cooling techn... more Ferroelectric materials are being actively explored for next-generation solid-state cooling technology. Even though bulk materials possess an advantage in terms of overall heat extraction capacity, their performance is limited due to low adiabatic temperature change. In this regard, the present article explores enhanced cooling capacity of bulk polycrystalline Pb0.99Nb0.02(Zr0.95Ti0.05)0.08O3 (PNZT) through external-field mediation and coupled caloric effects. Barocaloric (BC) and electrocaloric (EC) effects were indirectly estimated using polarization versus electric field (P-E) loops (under varying pressure and temperature). It was observed that under applied pressure of 325 MPa, ∆TEC could be improved from 1 K to 4.5 K. Similarly, a peak unbiased ∆TBC of 1.5 K could be enhanced to 5.3 K under an electric field of 5 MV.m−1. These figures correspond to an improvement of ~400% over the unbiased values. The results are indicative of the potential of multicaloric cooling capacity of bulk ferroelectric materials. This article is protected by copyright. All rights reserved.

Applied Physics Letters, 2016

Microcrystals of LiNbO3 (size ∼200 nm) can be selectively precipitated in a glass matrix which ca... more Microcrystals of LiNbO3 (size ∼200 nm) can be selectively precipitated in a glass matrix which can assist in the photocatalytic activity through ferroelectricity. Glass with the composition 30SiO2-35Li2CO3-35Nb2O5 was utilized for the process. A remarkably high Estriol (E3) degradation rate of 232.54 min−1 m−2 was obtained. The degradation was monitored using fluorescence spectroscopy with a detection limit in nanomolar (nM) range. From the fitting of fluorescence intensity versus time, it was observed that degradation of estriol follows a pseudo first-order reaction kinetics. The results indicate that LiNbO3 based glass-ceramics have a great potential to be employed as a well embedded photocatalyst.

Applied Physics Letters, 2016

Polyvinylidene di-fluoride-based polymers were investigated for elastocaloric and barocaloric eff... more Polyvinylidene di-fluoride-based polymers were investigated for elastocaloric and barocaloric effects. Bulk samples were subjected to uniaxial tensile and hydrostatic loading. Resulting strain profile (function of temperature) was used to predict the temperature change. A peak elastocaloric effect of 1.8 K was observed at 298 K (15 MPa). Alternately, a large barocaloric effect of ∼6 K was observed at 300 K (200 MPa). This was further improved to an astounding ∼19 K near 368 K (200 MPa). The results of this study are expected to greatly benefit the field of ferroelectric solid-state refrigeration and open another horizon for future exploration of multicaloric effects in ferroelectric polymers.

Phase Transitions, 2015

Development of a practical electrocaloric (EC) refrigeration system is hindered by four main draw... more Development of a practical electrocaloric (EC) refrigeration system is hindered by four main drawbacks: (a) low adiabatic temperature change near room temperature, (b) requirement of large electric field to achieve desirable temperature change, (c) low isothermal entropy change and (d) low thermal capacity. Here, we demonstrate that replacing Ca by Sr in the bulk ceramics of nominal composition Ba0.85Ca0.15-xSrxTi0.9Zr0.1O3, can address these shortcomings. Evidently, a large of 2.4 K can be obtained near room temperature (303 K) at relatively low electric field (37 kV.cm−1). These numbers indicate an EC performance that exceeds most bulk materials, surpassing even those reported for advanced thin-film composites. Further, a comparative analysis of the EC strength against reveals that the Sr modified composition is the optimum material, for EC cooling applications.

Materials, 2015

With an ever increasing dependence on electrical energy for powering modern equipment and electro... more With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE) display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

Applied Physics Letters, 2015