bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of multi-pulse formation in all-polarization-maintaining figure-9 erbium-doped fiber mode-locked laser*
Authors: Shi Jun-Kai , Dong Deng-Feng , Pan Ying-Ling , Li Guan-Nan , Li Yao , Liu Li-Tuo , Chen Xiao-Mei , Zhou Wei-Hu
Published: October 2020

We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase-biased nonlinear amplifying loop mirror to extract part of intracavity laser power as a laser output, and the dependence of output couple ratio of fiber coupler on the mode-locking state is experimentally investigated. The intracavity nonlinear effect is mitigated by lowering the intracavity laser power, which is conducive to avoiding the multi-pulse formation. In the meantime, the loss-imbalance induced by fiber coupler is helpful in improving the self-starting ability. With the proposed laser structure, the multiple pulse formation can be suppressed and high power single pulse train can be obtained. The laser emits three pulse trains which is convenient for some applications. Finally, the output power values of three ports are 5.3 mW, 51.3 mW, and 13.2 mW, respectively. The total single pulse output power is 69.8 mW, which is more than 10 times the result without OC2. The total slope efficiency is about 10.1%. The repetition rate of three pulse trains is 21.17 MHz, and the pulse widths are 2.8 ps, 2.63 ps, and 6.66 ps, respectively.
Quantifying entanglement in terms of an operational way*
Authors: Yu Deng-Hui , Yu Chang-Shui
Published: October 2020

We establish entanglement monotones in terms of an operational approach, which is closely connected with the state conversion from pure states to the objective state by the local operations and classical communications. It is shown that any good entanglement quantifier defined on pure states can induce an entanglement monotone for all density matrices. Particularly, we show that our entanglement monotone is the maximal one among all those having the same form for pure states. In some special cases, our proposed entanglement monotones turn to be equivalent to the convex roof construction, which hence gain an operational meaning. Some examples are given to demonstrate different cases.
First-principles study of co-adsorption behavior of O2 and CO2 molecules on δ-Pu(100) surface
Authors: Qi Chun-Bao , Wang Tao , Li Ru-Song , Wang Jin-Tao , Qin Ming-Ao , Tao Si-Hao
Published: October 2020

First principles calculation is performed to study the co-adsorption behaviors of O2 and CO2 on δ-Pu(100) surface by using a slab model within the framework of density functional theory (DFT). The results demonstrate that the most favorable co-adsorption configurations are Tv-C4O7 and Tp1-C2O8, with adsorption energy of –17.296 eV and –23.131 eV for CO2-based and O2-based system, respectively. The C and O atoms mainly interact with the Pu surface atoms. Furthermore, the chemical bonding between C/O and Pu atom is mainly of ionic state, and the reaction mechanism is that C 2s, C 2p, O 2s, and O 2p orbitals overlap and hybridize with Pu 6p, Pu 6d, and Pu 5f orbital, resulting in the occurrence of new band structure. The adsorption and dissociation of CO2 molecule are obviously promoted by preferentially occupying adsorbed O atoms, therefore, a potential CO2 protection mechanism for plutonium-based materials is that in CO2 molecule there occurs complete dissociation of CO2 → C + O + O, then the dissociated C atom combines with O atom from O2 dissociation and produces CO, which will inhibit the O2 from further oxidizing Pu surface, and slow down the corrosion rate of plutonium-based materials.
Sr-doping effects on conductivity, charge transport, and ferroelectricity of Ba0.7La0.3TiO3 epitaxial thin films*
Authors: Li Qiang , Wang Dao , Zhang Yan , Li Yu-Shan , Zhang Ai-Hua , Tao Rui-Qiang , Fan Zhen , Zeng Min , Zhou Guo-Fu , Lu Xu-Bing , Liu Jun-Ming
Published: October 2020

Sr-doped Ba0.7La0.3TiO3 (BSLTO) thin films are deposited by pulsed laser deposition, and their microstructure, conductivity, carrier transport mechanism, and ferroelectricity are systematically investigated. The x-ray diffraction measurements demonstrate that Sr-doping reduces the lattice constant of BSLTO thin films, resulting in the enhanced phonon energy in the films as evidenced by the Raman measurements. Resistivity-temperature and Hall effect measurements demonstrate that Sr can gradually reduce electrical resistivity while the electron concentration remains almost unchanged at high temperatures. For the films with semiconducting behavior, the charge transport model transforms from variable range hopping to small polaron hopping as the measurement temperature increases. The metalic conductive behaviors in the films with Sr = 0.30, 0.40 conform to thermal phonon scattering mode. The difference in charge transport behavior dependent on the A-site cation doping, is clarified. It is revealed that the increasing of phonon energy by Sr doping is responsible for lower activation energy of small polaron hopping, higher carrier mobility, and lower electrical resistivity. Interestingly, the piezoelectric force microscopy (PFM) results demonstrate that all the BSLTO films can exhibit ferroelectricity, especially for the room temperature metallic conduction film with Sr = 0.40. These results imply that Sr-doping could be a potential way to explore ferroelectric metal materials for other perovskite oxides.
High-frequency magnetic properties and core loss of carbonyl iron composites with easy plane-like structures*
Authors: Wang Guo-Wu , Guo Chun-Sheng , Qiao Liang , Wang Tao , Li Fa-Shen
Published: October 2020

To fully release the potential of wide bandgap (WBG) semiconductors and achieve high energy density and efficiency, a carbonyl iron soft magnetic composite (SMC) with an easy plane-like structure is prepared. Due to this structure, the permeability of the composite increases by 3 times (from 7.5 to 21.5) at 100 MHz compared with to the spherical carbonyl iron SMC, and the permeability changes little at frequencies below 100 MHz. In addition, the natural resonance frequency of the composite shifts to higher frequencies at 1.7 GHz. The total core losses of the composites at 10, 20, and 30 mT are 80.0, 355.3, and 810.7 mW/cm3, respectively, at 500 kHz. Compared with the spherical carbonyl iron SMC, the core loss at 500 kHz is reduced by more than 60%. Therefore, this kind of soft magnetic composite with an easy plane-like structure is a good candidate for unlocking the potential of WBG semiconductors and developing the next-generation power electronics.
Analysis of asymmetry of the D
α
emission spectra under the Zeeman effect in boundary region for D–D experiment on EAST tokamak*
Authors: Gao Wei , Huang Juan , Su Jianxun , Fu Jing , Chen Yingjie , Gao Wei , Wu Zhenwei
Published: October 2020

In 2015 campaign, deuterium atomic emission spectra (D
α
) under the Zeeman effect in boundary region had been measured by a high resolution optical spectroscopic multichannel analysis (OSMA) system based on passive spectroscopy during the deuterium plasma discharge on EAST tokamak, and part of the works about the Zeeman effect on D
α
spectra had already been done. However, the asymmetric phenomena of D
α
emission spectra under the Zeeman effect were observed in process of analyzing the spectral data. To understand the asymmetric phenomena and acquire the useful local plasma information, an algorithm was proposed and used to analyze the asymmetry of the emission spectra under the Zeeman effect with all polarization components (π and ±σ). In the algorithm, the neutral atoms were considered to follow the Maxwell distribution on EAST, and I
+σ
≠ I
−σ
was considered and set. Because of the line-averaged spectra along the viewing chord, the emission spectra were considered from two different regions: low-field side (LFS) and high-field side (HFS). Each spectral line was classified into three energy categories (the cold, warm, and hot) based on different atomic production processes in boundary recycling. The viewing angle θ (between the magnetic field B and the viewing chord), magnetic field B at two spectral emission positions (HFS and LFS) and the Doppler shift of all three energy categories of each spectral line were all considered in the algorithm. The effect of instrument function was also included here. The information of the boundary plasma were acquired, the reason for the asymmetric phenomena was discussed, and the boundary recycling during the discharge were studied in the paper. Based on fitting a statistical data of acquired fitting results, an important conclusion was acquired that the ratio of the spectral line intensity in HFS and LFS was proportional to the square of that of the corresponding magnetic field.
Microstructure, optical, and photoluminescence properties of β-Ga2O3 films prepared by pulsed laser deposition under different oxygen partial pressures*
Authors: Cui Rui-Rui , Zhang Jun , Luo Zi-Jiang , Guo Xiang , Ding Zhao , Deng Chao-Yong
Published: October 2020

The β-Ga2O3 films are prepared on polished Al2O3 (0001) substrates by pulsed laser deposition at different oxygen partial pressures. The influence of oxygen partial pressure on crystal structure, surface morphology, thickness, optical properties, and photoluminescence properties are studied by x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), spectrophotometer, and spectrofluorometer. The results of x-ray diffraction and atomic force microscope indicate that with the decrease of oxygen pressure, the full width at half maximum (FWHM) and grain size increase. With the increase of oxygen pressure, the thickness of the films first increases and then decreases. The room-temperature UV-visible (UV-Vis) absorption spectra show that the bandgap of the β-Ga2O3 film increases from 4.76 eV to 4.91 eV as oxygen pressure decreasing. Room temperature photoluminescence spectra reveal that the emission band can be divided into four Gaussian bands centered at about 310 nm (∼ 4.0 eV), 360 nm (∼ 3.44 eV), 445 nm (∼ 2.79 eV), and 467 nm (∼ 2.66 eV), respectively. In addition, the total photoluminescence intensity decreases with oxygen pressure increasing, and it is found that the two UV bands are related to self-trapped holes (STHs) at O1 sites and between two O2-s sites, respectively, and the two blue bands originate from

V

Ga

2
−

at Ga1 tetrahedral sites. The photoluminescence mechanism of the films is also discussed. These results will lay a foundation for investigating the Ga2O3 film-based electronic devices.
Rational solutions and interaction solutions for (2 + 1)-dimensional nonlocal Schrödinger equation*
Authors: Chen Mi , Wang Zhen
Published: October 2020

A chain of novel higher order rational solutions with some parameters and interaction solutions of a (2+1)-dimensional reverse space–time nonlocal Schrödinger (NLS) equation was derived by a generalized Darboux transformation (DT) which is derived by Taylor expansion and determinants. We obtained a series of higher-order rational solutions by one spectral parameter and we could get the periodic wave solution and three kinds of interaction solutions, singular breather and periodic wave interaction solution, singular breather and traveling wave interaction solution, bimodal breather and periodic wave interaction solution by two spectral parameters. We found a general formula for these solutions in the form of determinants. We also analyzed the complex wave structures of the dynamic behaviors and the effects of special parameters and presented exact solutions for the (2+1)-dimensional reverse space–time nonlocal NLS equation.
Hydrodynamic modeling of self-gravitating astrophysical objects on tetrahedral meshes
Authors: Kulikov Igor , Vorobyov Eduard , Chernykh Igor , Elbakyan Vardan
Published: October 2020

The paper proposes a new numerical method for solving the equations of gravitational hydrodynamics on a tetrahedral mesh. The proposed numerical method is focused on modeling the evolution of astrophysical objects of spherical shape, which is appropriate for gravitational collapse and star formation, and also for supernova explosion. The construction of tetrahedral grids is carried out in three stages. At the first stage, a geodesic grid methodology is used to construct a triangular grid on the surface of the sphere, which encompasses the computational domain. At the second stage, the resulting triangular mesh is serialized from the surface of the sphere to its center, and at the third stage, the obtained prisms are divided into tetrahedra. This approach allows us to simulate spherical objects without singularities that occur when using spherical or cylindrical coordinates. The paper describes numerical methods for solving the equations of hydrodynamics and the Poisson equation. Numerical examples are given that verify the developed numerical methods.
Computing the aerodynamic drag of fractal aggregates in free-molecular and transition regimes
Authors: Stoyanovskaya Olga , Suslenkova Anastasiya , Kusnatdinov Timur
Published: October 2020

For fine particles moving in the gas different regimes of aerodynamic drag are distinguished depending on their sizes and dust to gas relative velocities. In the Epstein or free-molecular regime, the drag force depends on the projected area or cross-section of the body, and in the Stokes or transition regime, on its linear size. Finding the linear size and the projected area for nonspherical particles is a non-trivial task. To describe the mobility of some type of nonspherical particles - fluffy aggregates, considered as a set of spheres - monomers, the value Df called fractal dimension is often used. For such aggregates with fixed fractal dimension D0, several authors suggested the approximations of the linear size (called Smoluchowski radius Rs) and projected area PA as a function of N - the number of monomers in the aggregate. These authors validated their approximations on experimental data. On the other hand, new direct numerical simulation (DNS) data on mobility of fractal aggregates have been obtained recently. In the paper we constructed new functions PA(Df,N) and Rs(Df, N) interpolating available from the literature approximations of PA(Df = D0,N) and Rs(Df = D0,N) and minimizing the deviation from recent DNS data. These functions are designed for global simulations of protoplanetary discs dynamics and planet formation, but can be used in different applications.
Three-dimensional hybrid numerical tool for collisionless plasma modeling
Authors: Sladkov A , Smets R , Korzhimanov A
Published: October 2020

Recent laser-produced plasmas experiments open up new opportunities for the so-called laboratory astrophysics, allowing observation and studying a number of fundamental physical processes relevant to magnetized plasmas, such as thermo-magnetic instabilities leading to magnetic field generation, magnetic reconnection, collisionless shocks. In order to supplement those experiments with full-scale numerical simulations we develop a code AKA52 (Arbitrary-Kinetic-Algorithm) implementing a hybrid model that includes the dynamics of magnetic fields: advection by the ion flow and Hall effect, magnetic field generation by the Biermann battery effect and Weibel instability. The fully-parallelized high-performance hybrid algorithm includes Particle-in-Cell (PIC) formalism for ions and a 10-moment fluid model for electrons that are described by density, bulk velocity and the six-component pressure tensor evolution equation. Laser-plasma interaction is simulated by means of an ablation operator which imitates laser ionization and heating at critical density surface. As an example, we chose a problem of plasma expansion in the externally applied magnetic field perpendicular to the flow that is related to a number of recent laser-plasma experiments.
Plasma equilibrium and stability in a current-carrying conductor vicinity
Authors: Brushlinskii K V , Stepin E V
Published: October 2020

Our paper is connected with a cycle of works on mathematical modeling of plasma confinement processes in the magnetic traps – Galateas. A magnetic field confining plasma is created in these traps by current-carrying conductors which are immersed in the plasma volume but not in contact with the hot dense plasma. The idealized models of strictly equilibrium configurations of infinitely conductive plasma in traps possessing symmetry are based on two-dimensional boundary value problems with the scalar Grad-Shafranov equation for the magnetic flux function. Magnetic traps have a perspective in the controlled thermonuclear fusion problem if plasma configurations in them are stable. In our former publications, a question about stability of the configurations around a straight conductor was raised and particularly solved. Here these studies are continued. An area of maximal pressure and a section of its decrease near the outer boundary are included into the considered vicinity. The main result is that the instabilities observed here can be weakened if the plasma pressure slowly decreases near the trap outer boundary.
Content of ontology for solving compute-intensive problems of the cosmic plasma hydrodynamics
Authors: Sapetina Anna , Glinskiy Boris , Zagorulko Galina
Published: October 2020

Modern mathematical modeling on supercomputer systems requires that researchers have both a view of the main aspects of a studied phenomena and a knowledge base of numerical methods and supercomputer technologies for solving natural science problems. Development of intelligent support systems for solving such problems can greatly facilitate the researcher work by providing convenient tools for constructing an efficient scheme of problem solution on a target computational architecture and, if possible, implementing it using already developed program codes.

This paper describes an implementation of this idea for the compute-intensive problems of the cosmic plasma hydrodynamics. A knowledge base has been developed, including ontological descriptions of studied astrophysical phenomena, their mathematical representations, numerical methods for solving set problems and supercomputer architectures that can be used for calculations. The paper presents patterns describing the main classes of the constructed ontology and their instances. The ontology can be expanded by a generation system of computational codes for the selected schemes of a problem solution.
Pair production and annihilation in advective accretion disks around black holes
Authors: Sarkar Shilpa , Chattopadhyay Indranil
Published: October 2020

We investigate the role of pair production and annihilation in the presence of radiation processes like bremsstrahlung and inverse-Comptonization, assuming no magnetic fields present in the system. The disk is assumed to be viscous, advective and in hydrostatic equilibrium. Photon-photon interactions leading to pair production is the most dominant process. Threshold for this process is,

h

v
1

h

v
2

>
∼

(

m
e

c
2

)

2

. We find that, for accretion rates lower than 0.8 M
edd, we can neglect the presence of any pairs. Maximum number of pair production occurs in a region < 50r
g. When the number density of pairs is optimal, a bump is observed near m
e
c
2 in the spectrum, which is a signature of the annihilated photons.
Birth of a hurricane: early detection of large-scale vortex instability
Authors: Levina G V
Published: October 2020

A way is substantiated for detecting new large-scale vortex instability in the tropical atmosphere. The instability may occur several hours or even several dozens of hours before the formation of a tropical depression or tropical storm. The diagnosis of instability was developed on the basis of data from idealized cloud-resolving atmospheric simulation for tropical cyclogenesis. It is suggested how the evolving instability may be traced by combining high-resolution numerical modeling and GOES Imagery. As an illustration, it is speculated and discussed that the instability may have emerged in future Hurricane Isaias (2020) when it had a status of Potential Tropical Cyclone for 36 hours before it was diagnosed as Tropical Storm.
An in vitro 3D diabetic human skin model from diabetic primary cells
Authors: Ozdogan Candan Yilmaz , Kenar Halime , Davun Kivanc Emre , Yucel Deniz , Doger Emek , Alagoz Sahin
Published: October 2020

Diabetes mellitus, a complex metabolic disorder, leads to many health complications like kidney failure, diabetic heart disease, stroke, and foot ulcers. Treatment approaches of diabetes and identification of the mechanisms underlying diabetic complications of the skin have gained importance due to continued rapid increase in the diabetes incidence. A thick and pre-vascularized in vitro 3D type 2 diabetic human skin model (DHSM) was developed in this study. The methacrylated gelatin (GelMA) hydrogel was produced by photocrosslinking and its pore size (54.85 ± 8.58 μm), compressive modulus (4.53 ± 0.67 kPa) and swelling ratio (17.5 ± 2.2%) were found to be suitable for skin tissue engineering. 8% GelMA hydrogel effectively supported the viability, spreading and proliferation of human dermal fibroblasts. By isolating dermal fibroblasts, human umbilical vein endothelial cells and keratinocytes from type 2 diabetic patients, an in vitro 3D type 2 DHSM, 12 mm in width and 1.86 mm thick, was constructed. The skin model consisted of a continuous basal epidermal layer and a dermal layer with blood capillary-like structures, ideal for evaluating the effects of anti-diabetic drugs and wound healing materials and factors. The functionality of the DHSM was showed by applying a therapeutic hydrogel into its central wound; especially fibroblast migration to the wound site was evident in 9 d. We have demonstrated that DHSM is a biologically relevant model with sensitivity and predictability in evaluating the diabetic wound healing potential of a therapeutic material.
Study of Emission Control on Stationary Diesel Engine by Scrubbing Technique with Sodium Bicarbonate Solution
Authors: Premkumar S. , Balaji G.
Published: October 2020

Increasing automobile emission is becoming a major problem for our environment. Wet scrubber technology is generally used in power plants and marine engines for emission control. In this study, this technique was applied to the internal combustion engine for its suitability and performance to control undesirable emissions. A 5.2 kW diesel engine with an eddy current dynamometer with water cooling and is used for this study. The sodium bicarbonate [NaHCO3] solution was chosen for the study. Experimental readings were taken with the fabricated scrubber at the exhaust with different engine loads (0, 1.3, 2.6, 3.9, and 5.2 kW). Chosen sodium bicarbonate solution was found to be very effective in reducing emissions. The sodium bicarbonate solution effectively absorbedthe NO and smoke emissions by 12.35% and 27.21%, respectively.
Production of Bio-Hydrogen from Agricultural residues : A Contemporary Review
Authors: Prem Balaji C , Mukundhan C , Shyam Kumar M.B. , Harish R.
Published: October 2020

With the increase in usage of bio-products of all sorts in the modern world, the waste obtained during the production phases has been a major concern for over a period of time. The accumulation of these wastage not only enhances various kinds of pollution, but also increases the carbon footprint. Considering these negative impacts brought about by poor maintenance of these wastages and advancements in the field of utilization of sustainable and renewable energy, it is very important to produce bio-hydrogen due to the limitations of using industry-produced hydrogen. Hydrogen, though having many advantages, like being environmentally friendly and highly efficient when used as a fuel, has been neutralized by certain drawbacks such as production of it in industrial set up is found to be expensive and the storage process is tedious because of its flammable nature. Therefore, production of bio-hydrogen is found to be vital. In our paper, we have touched upon various methods of preparation of bio-hydrogen from the by-products of the farms such as corn stover, corn straw and rotten apple. Production of bio-hydrogen from micro algae has also been stressed upon as it has been found be one of the most efficient method. But, most of the analysis has been done on corn stover based on ambient atmospheric conditions, factors that affect the process and comparison between photo fermentation, dark photo fermentation and dark fermentation has also been judged as an important criterion for enzyme saccharification. Another important method of production of production of hydrogen using tequila vinasses in presence of charcoal by dark fermentation process has also been reviewed in this paper
Evaluation of Sustainable Methods for Embankment Stabilization
Authors: Divya V , Asha M N
Published: October 2020

Technologies that can contribute to sustainable environment and enhance economic feasibility have been gaining importance all over the world. The researchers have taken advantage of locally available materials and renewable sources in order to accomplish sustainable and economic construction activities. Many research works have been carried out in the field of ground improvement towards developing techniques that causes minimum impact on the environment. Some of the conventional materials that have been used in the past for embankment stabilization are lime, cement, fly ash, silica fumes, GGBS etc. Enzymatic treatment of ground is one of the emerging multi-disciplinary solutions that targets environment sustainability through stabilization using bio-enzymes. In this method bio-enzymes, which is obtained from vegetable extracts, are used for improving the mechanical characteristics of the natural weak soil. In the current work, a comparative study has been performed for the analysis of the different techniques/materials used for improvement of embankment/sub grade resting on expansive soil. The expansive/problematic soil is spread across a large part of central and western India and poses challenges to engineers due to its high compressibility properties. The improvement in the compressive strength characteristics of expansive soils when stabilized using materials like lime, rice husk ash, stone dust, fibre and bio-enzyme are being compared and studied in this work. On comparison it is observed when the stabilizing agent is pozzolanic in nature, curing period plays a crucial role as far as improvement factor is concerned.
Solar Power Transforming the Face of Rural India: Climate Justice for All
Authors: Prema E. , Rajavenkatesan P.R.L.
Published: October 2020

The word “environment” is difficult to define. Its normal meaning relates to surroundings. The environment itself is combination of physical, chemical and biological factors surrounding an organism. Environment provides us a number of renewable and a non-renewable energy source such as solar power, wind-energy, natural gas, hydropower, biofuels, coal, petroleum etc., Renewables energies are playing a vital role in augmenting Grid powers, provide energy access reducing consumption of fossil fuels and also provides India to pursue low carbon pathway. There are so many steps taken by the international community in order to promote the solar energy. The Sustainable Development Goal 7 ensures access to affordable, reliable, sustainable and modern energy for all. The Paris Climate Change Agreement, 2015 has given hope for the carbon emission mechanisms that must be followed by the state parties. In our daily lives, the community as a whole must focus on reducing our daily energy consumption, migrating to renewable resources, using greener transport and adopting environmentally friendly technologies. Being a collective problem, climate change and emission of carbon needs collective solution. It is not new to the developing nations as solar productsis often low quality and negative experiences with substandard generic products damaged the receptivity of the potential consumers. It is important to note here that affordable price and high-quality standard products should be produced in the country itself. The solar power project will reduce and lead to carbon emission. In this paper, the importance of solar power and its usage for rural India will be discussed in detail in order to ensure the green environment.
Effect of nanofluids in waste cooking oil biodiesel fuel: An experimental investigation on diesel engine characteristics
Authors: Ramanathan V , Jaikumar M , Induja S , SangeethKumar E , SasiKumar N
Published: October 2020

The diminishing crude oil source and the environmental effluence created by the fossil fuels have forced the researchers to search for an alternative source of energy. Many researchers found that Waste cooking oil biodiesel (WCOB) derived from waste cooking oil (WCO) could be an economic source of fuel for diesel engines because some of the properties of WCOB were found similar to diesel. Disposing of WCO in sewage has been a great concern for many countries. Instead of disposing, converting WCO into WCOB, using them in diesel engines could be the best choice of utilizing energy. In this context, WCOB was selected as a basic fuel. In the first phase, experimentation was carried out using WCOB. Single-cylinder, water-cooled diesel engine with full set up was used for experimentation. Then, Zinc Oxide (ZnO) nanofluid was prepared by a wet chemical method in two mass proportions of 50ppm and 100ppm and blended with WCOB and considered fuels as WCOBZ50 and WCOBZ100. These fuels were tested and readings were measured. The experimental results showed that the engine characteristics were found better for WCOBZ100 compared to neat WCOB. In the second phase, ZnO with Copper Oxide (CuO) mixed nanofluid was prepared in two mass proportions of 50ppm and 100ppm and considered fuels as WCOBZC50 and WCOBZC100. Then these fuels were tested and results were evaluated with previous results. Finally, it was found that greater improvement in engine output characteristics and extreme drop in emission gases for WCOBZC100 compared to other nano blends and neat WCOB.
Numerical study of thermal cooling for Lithium-ion battery pack using phase change material
Authors: Rohit Kumar K , Sharan V , Harish R , Shyam Kumar M B
Published: October 2020

The objective of this study is to numerically investigate the battery thermal management of electric vehicles using phase change material. The lithium-ion batteries which are widely used in electric vehicles have an optimal operating temperature range from 25°C to 60°C, above which the battery does not operate effectively. There are various cooling methods such as active cooling method and passive cooling method. The present study is based on passive cooling method where the thermal performance of different phase change materials such as paraffin wax, extended graphene and capric acid are compared for different heat source intensities. The numerical simulation is performed using Ansys Fluent by considering the melting and solidification effects of the phase change materials. The investigation is performed by varying the thermo physical properties of the phase change materials and temperature of the battery packs. The results are analysed by plotting the temperature and velocity contours and the melting and heat transfer rates of different phase change materials are also compared. The results from the present study would be useful in identifying the ideal phase change material with improved thermal performance characteristics.
Thermal analysis of phase change materials inside a square enclosure
Authors: Bahuguna Aviral , Harish R. , Shyam Kumar M.B
Published: October 2020

Rising challenges in electric mobility and computing domain to control and condition the temperatures inside circuit boards and motor control drivers call for efficient and effective heat sink designs. Phase change materials come handy and have applications in conditioning temperatures in electronic devices. They prevent failures and increase their efficiencies at different temperatures and conditions. In the present study, the complex flow physics of phase change materials during melting is studied, inside a square enclosure with a heat source mounted at the bottom wall. The walls are assumed to be adiabatic, the material properties of heat source are that of silicon at 330K. The turbulent natural convection flow is modeled by the computational fluid dynamics (CFD) approach using Reynolds averaged Navier-stokes equation (RANS) with Lambremhorst k-ε turbulence model. A finite difference method is employed to discretize the governing equations. An in-house CFD code was computed for simulating the convective heat transfer characteristics. The flow physics of three different phase change materials (n-Octadecane, PEG900, and Paraffin (RT60)) have been analysed for a fixed Grashof number value of 103. The transient flow characteristics are examined by plotting the stream function, velocity, and temperature variation with time of the phase change materials.
Study on Design modifications and feasibility in Conversion of scroll compressor into Scroll expander for using as battery charger.
Authors: Kottapalli Aparna , Rama Krishna K.
Published: October 2020

Scroll expanders are well suitable for low grade power production with an ORC. In this paper, scroll compressor design aspect in conversion to a compact scroll expander is taken. The major application of scroll expander is to generate power. The investigation of its application to charge batteries in automobiles is done to extend its application range. This analysis is done in two stages. In the first stage, a refrigeration scroll type compressor is taken to make it as a scroll type expander, as the availability of scroll type expanders are not wide in range. Its design modification has taken to make it compact and suitable for use as a battery charger with compressed air as working fluid. A mathematical simulation is done to find the design and thermodynamic properties like redesigning of the shaft to maintain eccentricity of rotating scroll and pressure ratio that influence the mechanical power developed in the scroll expander. A proto type of scroll expander is developed to conduct experiments for further analysis. In the second stage, the numerical feasibility analysis is done to verify the factors like speed and torque that influence the electrical power generated through mechanical work. In the trails carried, a voltage of 12.23 has been developed at inlet pressure of 15 bar and temperature of 303k.
Simulation of heat transfer characteristics of phase change material dispersed with Titanium oxide nanoparticles in horizontal channel
Authors: Sourang S , Harish S , Harish R , Shyam Kumar M B
Published: October 2020

Phase Changing Materials (PCM) is proving to be one of the major breakthroughs in industries as it has various applications in sustainable and renewable energy. The present study investigates the melting and solidification of phase change material (ice) in the presence of titanium oxide nanoparticles in a horizontal channel with internal heat source. The parametric study is carried out by varying the inlet velocity, heat source strength and nanoparticle volume fractions. The problem is modeled as three-dimensional laminar steady flow considering the effects of melting and solidification using Ansys Fluent. The heat sources mounted at the lower wall of the channel are specified with constant wall temperature boundary condition and the remaining walls are considered as adiabatic. The forced velocity inlet boundary condition is specified for the longitudinal velocity at the inlet and pressure outlet boundary condition is considered at the outlet of the channel. The results are analyzed by plotting the pathlines, longitudinal velocity contours, pressure and temperature contours. The results indicate that the longitudinal inlet velocity significantly affects the flow and heat transfer characteristics inside the horizontal channel. The increase in inlet velocity strengthens the melting rate and increases the heat transfer rate inside the channel. It is also found that the melting rate increases linearly with increase in the heat source intensity and nanoparticle volume fraction.
Experimental and Numerical Investigation of Car Cabin Temperature under Solar Load Condition using Phase Change Materials
Authors: Srusti Bhargava , Aravind S , Yadhu K , Aashish V , Shyam Kumar M.B.
Published: October 2020

Cars kept in open have the tendency to attain temperatures far higher than the one prevailing in the surroundings. This condition is especially severe during summer months, and can cause a lot of discomfort to passengers, who re-occupy the car after parking it in the open for a while. Employing a Phase Change Material (PCM) can be a possible solution to control the car cabin temperature to a certain extent. This paper is focused on experimental and numerical study on employing a suitable PCM to control the car cabin temperature. Four different locations inside the car cabin namely roof, head, bottom and feet were selected for monitoring the temperature using temperature sensors. The effect of 90 minutes of exposure to the solar load is simulated by employing the Surface to Surface (S2S) radiation model available in ANSYS FLUENT 18.2. Experimental and numerical results conveyed the reduction in cabin average air temperature by ∼ 8°C after Placing the phase change material inside the four wheeler cabin. Comparison of Numerical and experimental results was carried out and the absolute average deviation in temperature predicted by S2S model from the experimental data is 9.93 %.
Effect of Phase Change Material and orientation angles on the efficiency of hexagonal solar Photo-voltaic module
Authors: Raj Chhetri Aditya , Russell John Barreto , Das Arunabha , Venugopal T. , Gobinath N.
Published: October 2020

Electricity has been paid much attention towards its entry in all sectors of human life, ever long since its revolutionary invention. Networking the disconnected hamlets with reliable electricity is still found to be challenging in many countries, due to demographic conditions, where electricity remains elusive. Solar energy, a form of renewable energy that has been proved to be a viable alternative to fossil fuels could bea potential solution for regions with poor distribution of power. The present work aims t augmenting the solar energy harvesting in a PV module with a phase change material. A portable PV module is fabricated based on an innovative design including passive cooling with paraffin wax and arrangements for enhanced solar irradiation. The new design is tested for its performance at different temperatures and it is found that the module with PCM has shown 3% of increase in voltage generation over the conventional one. Also, paraffin wax is found to maintain the module temperature at 5% lesser than the normal one on an average. Five different angles of orientation of the mirrors say, 30°, 45°, 60°, 75° & 90° with module axis are tested and it is observed that 60° is optimum in harvesting the voltage. The results revealed that the new design is more efficient and viable for its usage.
Prediction of Thermal Performance of Cooling Tower of a Chiller Plant Using Machine Learning
Authors: Karunamurthy K , Chatterjee Debdutta , Pattanashetti Shivam , Chhetri Aditya , Sevugan Aswin , Suganya G
Published: October 2020

Chiller plants (CP) are accountable for regulating the comfort levels of most indoor environments. The CP uses water as the working medium and acts as a centralized cooling system for the controlled cooling of products, in the different production environments, machine tool industries, 3D printing, packaging, heat exchanging systems and to preserve agricultural produce, dairy products, and other edible items. The CP under study is used for providing cooling to sixteen storeyed hostel building at VIT Chennai. The refrigerant used in this system is Tetra fluoro ethane (R134a). The chilled water (ChW) from the evaporator is circulated to the rooms in the hostel through the secondary circuit and the air handling unit exchanges chillness from the chilled water and finally supplies to the hostel rooms. The chilled water from the hostel returns to the evaporator in a closed loop. The cooling water (CW) from the condenser of the refrigeration system rejects heat to the cooling tower (CT). Thus the performance of the CT is directly linked to the performance of the cooling provided to the hostel rooms. The objective of this research is to predict the temperature at the outlet of the CT integrated with the CP using machine learning algorithms. The predicted values are compared with the measured values and with the values calculated theoretically. The results are analyzed using the standard metrics and are observed to be appreciable.
A Review of the Origin and Evolution of FSR Norms to Propose New Indices for Green Buildings
Authors: Vinoth Wilfer Geraj
Published: October 2020

Construction technology has transformed into hyper technological mode due to convergence of science of building materials, AI simulations and IOT tools of building management. However, the regulators evaluation of the built up space remains static for decades since the emergence of mega cities since the end of the World War II. There is a gap in the domain of building evaluation corresponding to the converging technologies. This paper reviews the origin of FSR (floor space ratio) and proposes suggestions for introducing new norms that are similar and comprehensive when compared to FSR norms. It would be a key policy measure to scientifically ensure sustainable development in the construction industry to stimulate resilient building designs and construction practices.
Development of a Polygeneration System for a Rural Community
Authors: Kamesh M R , Girishkumar G S , Kajampady Aneesha
Published: October 2020

Energy plays a very important role in the economic development of a country. Almost 85% of the primary energy comes from fossil fuels. Meanwhile, it is necessary to reduce carbon footprints to protect environment from the way of production and consumption of energy. To overcome this, adoption of a poly-generation system is the most effective way. It can be said as one of the most effective method to enhance energy efficiency, reduce energy consumption and control environmental pollution. It is the combination of several renewable energy using systems in a way that the output of one system becomes the input for another. Also, a number of utility outputs are obtained. This way, the amount of useful energy in the given amount of input is harnessed to a maximum extent, thus maintaining a very high energy efficiency. In this present work, our objective is to propose a techno-economical and techno-feasible polygeneration system for the selected three villages by using Homer Pro software. For this number of renewable energy systems like solar PV, biomass, hydrokinetic systems, wind turbine, hydrogen etc. are combined in an optimal way suitable for 3 different villages in south India. This is done by taking into account the availability of resources in the corresponding geographic area and also the utility products/outputs and deliverables on demand with the aid of an energy software called Homer Pro.
Numerical investigation of aerodynamic performance of a H-Darrieus wind turbine under turbulent flows
Authors: Mason Ashley A. , Harish R. , Shyam Kumar M.B.
Published: October 2020

In the present study, numerical investigation is performed on a H-Darrieus wind turbine under turbulent flow conditions. The turbine contains 3 rotor foils, NACA-0012 with 0° angle of attack, placed at 120° apart from each other, with rotor casing close to the airfoil. The inlet is considered to be velocity inlet and outlet to be pressure outlet while the side walls are given symmetric boundary conditions, as the walls are considered to be infinity. The airfoils are rotating at 150 R.P.M.. The meshing is done using Hexa-Dominant element to capture the flow very precisely and inflations are given wherever necessary. The problem is considered as two-dimensional, and the analysis of the model under the condition of turbulent flow is modeled using S.S.T-k-ω turbulence model. Simulation is performed using finite volume solver Ansys Fluent 2019-R2. The performance of the H-Darrieus wind turbine is analyzed, by varying the wind speed and turbine rotational speed. The further investigations are performed by comparing the flow characteristics between a stationary and rotating turbine. The results are analyzed by plotting the streamlines, velocity and pressure contours. The flow is analyzed at 6m/s, 8m/s, 10m/s as inlet freestream velocity and also by varying the rotor dimension, which was initially made as small as possible. The results indicate that the wind speed and rotational speed significantly influences the significant aero characteristics of the model of the wind turbine. The present results are validated and are in good accord with the benchmark results available in literature.
Environmental impact assessment on renewable energy: A review
Authors: Yadav Arunkumar , Hema H C , Shivakumara M J
Published: October 2020

In this modern era, urbanization is increasing at a higher rate; also the government is already planned for smart cities as well. In one word we can call it is a digital world. Hence the energy consumption is increased rapidly. In recent times several probable keys to the existing environmental concerns related to toxic pollutant discharges have developed to identify and decision making for sustainable energy resolutions connected with green buildings to come across future energy demands. There are renewable sources and they are utilized in a greater manner. In this paper, an attempt is made to review on different Renewable sources of energy like wind and tidal energy, hydropower, sugarcane ethanol, water pumping systems, the concept of green buildings, lignocellulosic bioethanol, solar energy, and Li-Ion batteries. The review includes both advantages and disadvantages of the mentioned energy sources. This Paper gives a brief discussion of different sources of renewable energy and their impact on the environment.
Zonal-distributed structuring of working bodies of the agricultural sector
Authors: Motorin V A , Gapich D S
Published: October 2020

Increasing the wear resistance of working bodies of tillage machines is an urgent problem of the agricultural sector. During the operation of tillage machines, their working bodies, including cutting blades, are subjected to dynamic loads, abrasive and chemical effects of the external environment, which provokes their wear. A promising direction for increasing the wear resistance of chisel bit cutting blades is to manufacture them from gray cast iron, which has the ability to bleach, i.e. it can form a very hard and wear - resistant cementite eutectic (ledeburite) along with graphite eutectic. The results of comparative tests for wear of medium-carbon and high-carbon steels after thermal hardening and a sample of gray cast iron SHC 30 are presented. The optimal method of strengthening chisel plough bits cast from gray cast iron is proposed, which allows to increase their wear resistance. Replacing expensive materials, alloys and technologies with non-alloyed cast iron with a wear-resistant structure will significantly reduce the cost of working bodies of tillage machines. Proposals for the technology of obtaining castings for the manufacture of working bodies of tillage machines will improve their operational reliability.
Tillage implement with vibrating working body
Authors: Kosulnikov R A , Konovalov P V , Gapich D S , Karsakov A A
Published: October 2020

A tillage implement with a vibrating working body based on a chisel cultivator allows to reduce the implement traction resistance by creating resonance to 35%. The use of an eccentric vibration generator contributes to a significant reduction in tillage operation energy costs, due to the decrease in the strength characteristics of the soil itself, without leaving the agrotechnological requirements framework.