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Bismuth ferrite has been under intense research for many years as it can exhibit first- and second-order transitions where all the phases have distinct properties encapsulating various exciting phenomena. This work reports a computational study of bismuth ferrite and its varied phases using density functional theory with the implementation of Hubbard correction for increased accuracy. The proposed method is validated through Linear Response Theory using Quantum ESPRESSO. The phase transition and the mechanical properties are explored by calculating elastic tensors for different polymorphs. A negative Poisson's ratio for the tetragonal phase supporting its growth in compressive environments is predicted. The electronic properties of different phases of bismuth ferrite are explored, which helps in understanding properties such as charge transfer excitation, metal–insulator transition, ferroelectric nature based on lone pair charges and orbital hybridization. The phonon modes of different phases are also investigated. Graphical abstract

Higher solar absorptance and lower thermal emittance are the key factors for solar collectors. The use of thin films that are having mechanically resistant coatings are common practice in industries. The primary motivation of carrying this research work is to lower thermal emittance and maximize solar absorptance on SS304 substrate material. W-Al2O3 composite coatings are developed using magnetron sputtering process by considering the process parameters. The experimental plan is achieved based on Taguchi L9 orthogonal under various levels for deposition parameters. The tungsten and alumina thin films deposited using a co-sputtering were characterized using 410 - solar instrument for measuring solar absorptance and ET 100 Emissometer for measuring thermal emittance. The optimization for process parameters on thermal emittance and absorptance were carried out. It was found that for deposition parameters of DC power 750W, RF power 1050W and Argon gas flow rate of 250 sccm, absorptance of 0.758 with thermal emittance of 0.061 is observed with deposition was carried out on SS304 substrates.

Increase in population, hasty industrialization, rampant urbanization, etc. have put forth tremendous pressure on all natural resources in general. Natural water resources are rapidly depleted due to increased utilization for domestic activities in urban areas. A proper monitoring system for the same is absent in most cases and poor management of the water resources leads to severe water stress in most of the Indian metro cities. NITI Aayog, the policy think tank of the Government of India, has predicted that many cities in India will march towards the Day Zero in 2021 with the ground water table becoming alarmingly low leading to severe water crisis. Grey water (recyclable water) treatment and its use are thus becoming increasingly important with the rise in demand for water within the urban areas. This research aims at quantifying the recyclable grey water in two selected case study areas in Thiruvananthapuram in Kerala, India, and to propose an appropriate strategy for utilization of grey water reuse in the residential societies and community. Based on several trials, the grey water treatment design/prototype was found to be performing well with treatment potency in the range of 60–70%. The efficiency is likely to improve if the same was adopted in large scale. This concept will help to improve the water management in large urban areas and the ground water resources.

Solar energy has environmental benefits by reducing the pollution and global warming resulting in cleaner water and air. One of the key factors is the absorber surface for entrapping the solar energy that is receiving from solar spectrum under the wavelength range of 250–2500 nm. Generally, absorber surfaces are made of thin films that are mechanically resistant and are common practice in the optical industries. Motivation to carry out this research work is to develop nanocomposite thin films coatings for maximizing solar absorptance and minimizing thermal emittance. W-Al2O3 composite thin films are developed by co-sputtering process upon consideration of process parameters. Design of experiment has been adopted to study the deposition parameters and analysis. Characterization of deposited thin films was performed to determine the solar absorptance and thermal emittance using 410-Solar and ET 100 Emissometer, respectively. It was found that for deposition parameters of DC power 750 W, RF power 1050 W and argon gas flow rate 250 sccm, an absorptance of 0.709 and thermal emittance of 0.175 are observed. From the SEM analysis, the average particle size of alumina is around 0.25 μm. EDAX was performed to determine the material composition of deposited thin films. This type of coatings requires for industries manufacturing solar cooker, solar water heaters and solar driers.

This paper considers finding a path in real time for a robot from the given initial position to the goal position. The environment is assumed to be mapped (known completely) and the resulting path should avoid all the obstacles, both static and dynamic in the mapped environment. The robot’s (agent) dynamics is assumed to be discrete LTI with process noise and is controlled with a finite set of inputs. An MDP formulation and a solution based on Deep Reinforcement Learning framework are presented for the problem. Numerical experiments are performed for the proposed method using Deep Q-Network algorithm and the results are compared with the state of the art sampling based path planning algorithms for both static and dynamic environments. It is shown that even though the proposed algorithm provides a sub-optimal path, the computational time is shown to be significantly faster compared to the traditional methods of path planning.

The study of microbes in and around us that have a drastic affect on human health plays a vital role in medicine. Bacterial infections kill millions of people in the world. The structured formation of bacterial communities, known as biofilms, is the major cause of bacterial infections. Nosocomial infections are caused by biofilms due to their pathogenic nature. Biofilms contribute about 80% and 65% to chronic and microbial infections respectively. The adhesion of bacteria to implant surface is the source of biofilm formation. Therefore, the surface characteristics of the implant material dictate the host cells association and response. Biofilms are resistant to antibiotics, disinfectants, and the human immune system. Implants surface modifications play a vital role in improving their biocompatibility and anti-infection properties. Providing antibacterial and adhesion resistant surface coating acts as a novel approach to combat biofilms. This review presents the process of biofilm formation on different implants and the next generation of surface modification techniques to enhance biocompatibility and antimicrobial functionality using surface engineering and nanobiotechnology..

Multiferroic materials belong to the sub-group of ferroics possessing two or more ferroic orders in the same phase. Aizu first coined the term multiferroics in 1969. Of late, several multiferroic materials’ unique and robust characteristics have shown great potential for various applications. Notably, the coexisting magnetic and electrical ordering results in the Magnetoelectric effect (ME), wherein the electrical polarization can be manipulated by magnetic fields and magnetization by electric fields. Currently, more significant interests lie in significantly enhancing the ME coupling facilitating the realization of Spintronic devices, which makes use of the transport phenomenon of spin-polarized electrons. On the other hand, the magnetoelectric coupling is also pivotal in magnetic memory devices wherein the application of small electric voltage manipulates the magnetic properties of the device. This review gives a brief overview of magnetoelectric coupling in Bismuth ferrite and approaches to achieve higher magnetoelectric coupling and device applications.

Crystallographic and electronic structures of phase pure ternary solid solutions of Ni

Band structure tailoring has been a great avenue to achieve the half-metallic electronic ground state in materials. Applying this approach to the full Heusler alloy Fe2TiSn, Cr is introduced systematically at Ti site that conforms to the chemical formula \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Fe}}_{2} {\text{Ti}}_{{1 - x}} {\text{Cr}}_{x}$$\end{document}Fe2Ti1-xCrxSn. Compositions so obtained have been investigated for its electronic, magnetic, and electrical transport properties with an aim to observe the half-metallic ferromagnetic ground state, anticipated theoretically for Fe2CrSn. Our experimental study using synchrotron X-ray diffraction reveals that only compositions with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$x \le$$\end{document}x≤ 0.25 yield phase pure L2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_1$$\end{document}1 cubic structures. The non-magnetic ground state of Fe2TiSn gets dramatically affected upon inclusion of Cr giving rise to a localized magnetic moment in the background of Ruderman–Kittel–Kasuya–Yosida (RKKY) correlations. The ferromagnetic interactions begin to dominate for x = 0.25 composition. Results of its resistivity and magnetoresistance (MR) measurement point towards a half-metallic ground state. The calculation of exchange coupling parameter, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {J}_{{ij}}$$\end{document}Jij, and orbital projected density of states that indicate a change in hybridization between 3d and 5p orbital, support the observations made from the study of local crystal structure made using the extended X-ray absorption fine structure spectroscopy. Our findings here highlight an interesting prospect of finding half-metallicity via band structure tailoring for wide application in spintronics devices.

Fluid motion in compression ignition engine is induced during the induction process and later modified during the compression process. The main problem in compression ignition engine is improper combustion which is due to improper mixing of air and fuel due to shorter delay periods. In conventional engines, air motion is linear and there is no rotational flow of air which leads to improper mixing of air and fuel within the shorter delay periods. In order to enchance proper mixing a secondary motion is to be provided to the air so that it properly mixes with fuel for shorter delay periods which increases engine performance and reduce emissions due to complete combustion, in order to provide secondary motion to the air the design of intake manifold is changed which provides rotational movement to the air instead of linear motion which enhances proper mixing of air and fuel leading to the variation of many engine performance parameters along with emissions. In this work, different designs of intake manifolds are considered and the performance parameters and emissions are calculated and compared with conventional engine.

The different types of human exercises particularly those recognized with development, signifies outflow of ozone depleting substances, greenhouse emissions that outcome into an Earth-wide temperature boost and environmental change. This affects nature and leads to imbalance in the environment and ecosystem. Henceforth it has turned out to be important to reduce dangerous atmospheric changes by some sustainable mitigation processes. In all the greenhouse gases, CO2 is the main compound that adds to a worldwide temperature alteration. Thus it is fundamental responsibility for every person to control the carbon outflow by understanding the concept of sustainable development. Carbon footprint estimation for an institutional and residential building was done separately for each component of structure or as a whole organization. The reason for this investigation includes distinguishing proof and examination of different emission inventories and the measure of carbon transmitted by them regarding an institutional structure and the residential building materials also assessed. Furthermore this study examines the current methodologies and approaches to estimate carbon footprint in an institutional building and residential building in Karnataka. To ascertain the status of carbon emission in the residential building materials a study was carried out in a proposed residential structure. It was concluded that the existing institutional building is carbon positive and also the amount of carbon emission by building materials used in the residential building also contribute to carbon footprint results to carbon positive. So as to lessen the emission and to convert the institutional structure and the residential building materials from carbon positive to carbon negative, general mitigation measures are recommended and by implementing the same how much carbon emissions also reduced was discussed .This research study also helps in creating awareness about the impact of amount carbon emissions happening in an institutional building due to different activities among the students, faculties and other public/Stake holders.

An aero-engine fir tree blade disc assembly is much proven to fretting fatigue damages due to centrifugal and vibrating conditions. This paper examines the effect of disc speed, contact angle and co-efficient of friction on fretting responses such as equivalent von-Mises stress, maximum shear stress and contact pressure by adopting Taguchi based grey relational analysis and RSM. All of the fretting responses were influenced by disc speed and contact angle. Multi response optimization achieved using grey relational analysis indicated that minimum equivalent von-Mises stress (0.63 MPa), shear stress (0.36 MPa) and contact pressure (0.681 MPa) are achieved at 260 rpm of disc speed, 17.5° of contact angle and 0.3 co-efficient of friction. Significant improvement was noticed in terms of stress concentration reduction at optimal conditions. Confirmatory simulation runs were performed to ensure the grey relational analysis results.

Borosilicate glass finds applications in micro-fluidic devices, micro-electro mechanical devices (MEMS) due to its bio-compatibility, optical transparency and anodic bonding capability with silicon wafer. Abrasive jet machining (AJM) is a potential process to machine low machinability brittle materials like borosilicate glass and ceramics with low specific power consumption and high material rates. This paper presents the details of developed micro-abrasive jet machine prototype and the experimental investigations on the influence of mixing chamber design on material removal rate in machining of borosilicate glass. Pressure, stand-off-distance, nozzle diameter, abrasive type (Al2O3 and SiC) and abrasive size were used as control factors. Experiments were conducted based on L16 orthogonal array and optimized with Taguchi’s method. ANOVA was performed to find the significant control factors and their percentage contribution. A multilayer perceptron artificial neural network (ANN) model was used with back-propagation algorithm to predict and validate experimental results. Experimental values of material removal rate with both the fixed and oscillating mixing chamber were compared with the predicted values. It was found that the oscillating mixing chamber has resulted good material removal rate and less spread for the given control factor combination due to uniform mixing of abrasive particles with compressed air

Objectives: Stealthy attacks are a kind of attacks which injects route fabrication information and producing false identification in network. In this paper, we evaluate these two stealthy attacks against a privacy mechanism as Distinct Authentication Key Approach (DAKA) in MANET. Methods/Statistical Analysis: Wireless networks are becoming the most popular in today communication systems, where users prefer to have wireless connectivity regardless of its geographic location. However, the openness of wireless communications increases the threat to MANET under its conditions. It is very challenging to validate false identify in a stealthy node behaviour as it gives a normal impression and in case of route fabrication they modify the routing path which leads a high number of packet loss. The DAKA provides a Secure Route Discovery Mechanism and data routing through a privacy and certificate authentication methodology. Findings: We evaluate the proposed approach by measuring Packet Delivery Ratio, Avg. End-to-End Delay, Control Overhead and Packet Drop Ratio with varying the number of malicious nodes in a fixed number of nodes and traffic. Application/ Improvements: The simulation experiment result shows successfully alleviation of the malicious nodes and achieves the needed performance.

This paper reports experimental investigation of effect of laser parameters on the drilling responses of alumina coated aluminium substrates using 1.8 kW CO 2 pulsed mode laser. Alumina was deposited on 4 mm thick Al 6065 plates by plasma spray technique. The main influencing factors were: Laser power on spatter deposition and Heat Affected Zone; Pulse frequency on entrance and exit circularities; Piercing time on taper, heat affected zone and exit circularity. Genetic algorithm optimization results indicated simultaneous improvement of 5.2% in hole quality at 416.6 W laser power, 1.4 kHz pulse frequency and 0.4 s piercing time. Response Surface Methodology indicated minimum spatter deposition area of 11.57 mm 2 , Heat Affected Zone 0.589 mm, taper 2.35° and maximum circularity at entrance 0.88 and exit 0.905 at 400 W laser power, 1.2 kHz frequency and 0.48 s piercing time. These results were in close agreement with those of Genetic algorithm. The optimum values were validated through confirmatory experiments.

In the developing countries increase in population, improper urbanization and industrialization causing many issues to the ecosystem and the environment. Industrial Pollution has been a great concern for decades. Mainly Tanning industries located in many places of India as small scale industry. These small scale industries mostly running in the houses discharge partially treated and untreated effluents with high concentration of Chromium V1 into the water bodies. Research Study was initiated with proto type lab scale model to identify a suitable alternative technique to reduce the concentration toxic compound present in Chrome tannery wastewater. Coupling of two techniques like constructed wetland and Biochar as adsorbent. Main objective is to identify the efficiency of constructed wetland with coconut shell biochar as an adsorbent. Constructed wetlands (CWs) are artificial developed engineered systems which are formulated and constructed to operate the natural processes like vegetative wetlands, natural soils, with connected microbial assemblages helps in treating wastewaters by the action of filtration, adsorption, sedimentation and phytoremediation. Biochar was produced from the coconut shell which was heated to temperatures between 250 and 750°C, under less oxygen concentrations. Constructed wetland coupled with Biochar. The biochar was mixed into the substrate of constructed wetlands. By using the biochar substrate the constructed wetland coupled with biochar was developed as lab scale model. Different trails were carried with the model using tannery wastewater collected from local tannery unit. The adsorbent biochar acts as a treating media which reduces the color of the wastewater and also reduction in chromium concentration of wastewater.The constructed wetland assemblage helps in reduction of other organic concentration and total solids of the wastewater. Based on the different trials in the lab scale model a good reduction in color, chromium, BOD, COD can be observed. More than 60 to 70 % reduction efficiency was achieved with the help lab scale model. It is possible to achieve 4’R (Reduce, Reuse, Recycle and Recovery) if the same was carried out in a large scale.

From the past decades, a vast amount of research is going on to find the cooling solutions for electronics involving numerous applications. In various sectors such as CPU coolers, LED coolers, relay cooling systems, battery cooling systems, aviation electronic components cooling systems, etc. The major problem involving electronic components cooling is the design of heat sinks and their compatibility with the electronic components for the specified applications. Also, the fast-paced advancements in computing leading for the creation of high-performance processors with integrated and complex circuits for which the cooling became a difficult task which is challenging the present market. This study aims at developing a metal matrix composite (MMC) heat sink for low coefficient of thermal expansion (CTE) electronic components cooling. Three groups of Al, SiC, and AlN are used to prepare three MMC prototype heat sinks. The mechanical and thermal properties of prototype combination MMC specimens were evaluated experimentally. The performance enhancement investigations on the prototype heat sinks were carried out in an insulated rectangular duct under forced convection at a constant heat flux of Q = 60 W and at 28°C, 101.325 kPa ambient conditions. The experiment is carried out at wind velocities ranging from 1 m/s to 4 m/s with an interval of 0.5 m/s. Results show that for GIIC MMC prototype heat sink the thermal resistance was significantly reduced by 35.25% on average and for every 1 W of pumping power the thermal resistance was decreased by 1.056% on average.From the past decades, a vast amount of research is going on to find the cooling solutions for electronics involving numerous applications. In various sectors such as CPU coolers, LED coolers, relay cooling systems, battery cooling systems, aviation electronic components cooling systems, etc. The major problem involving electronic components cooling is the design of heat sinks and their compatibility with the electronic components for the specified applications. Also, the fast-paced advancements in computing leading for the creation of high-performance processors with integrated and complex circuits for which the cooling became a difficult task which is challenging the present market. This study aims at developing a metal matrix composite (MMC) heat sink for low coefficient of thermal expansion (CTE) electronic components cooling. Three groups of Al, SiC, and AlN are used to prepare three MMC prototype heat sinks. The mechanical and thermal properties of prototype combination MMC specimens were evaluated ...

Due to exhausting fossil fuels and rising costs of the derivatives of fossil fuels, increasing instabilities of the energy market and global warming, the interest in the renewable sources of energy are increasing especially the wind energy. At low wind speeds and for off-grid power generation on a small scale, VAWT possesses the greatest potential than other types of wind energy conversion systems. This works aims to study the influence of auxiliary straight blades, slat and flaps arrangement configured to the micro-Darrieus style wind turbine model on its performance which is developed specifically for energy conversion on a small scale at low wind velocities. The micro-wind turbine model in the present work comprises of three sets of five airfoils. Each set comprises of an auxiliary airfoil, the main airfoil, a slat and two flaps configured at the leading edge and the trailing edge of the main airfoil with multiple chord lengths. The proposed model, the Darrieus model having standard blades configuration and auxiliary straight blades configuration are designed in Solidworks. The wind tunnel experimentations were carried out on the additive manufactured (AM) models 3D printed by SLS technique to compare their performance. The outcomes of the study were expressed in terms of dimensionless torque, moment and power coefficients for performance evaluation analysis. The proposed blades configuration showed a best self-starting ability at low wind velocity and high value of torque coefficient than the micro-Darrieus style wind turbine with standard configuration and auxiliary blades configuration. From this study, it was also found that the wind turbine with the configuration of the proposed blades showed a reduction in cut-in-speed.