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Present work deals with the study of rheological aspects related with finer particles of Fly Ash (FA) slurry suspension. The effect of sodium sulfate as an additive has been studied with three different proportions in basic slurry suspension. Throughout the investigation the shear rate varies from 50 to 200 s−1. In this study, additive shows a promising trend in order to improve the rheology of fine particles slurry suspension. The high viscosity reduction associated with the suspension of FA slurry is characterized by high concentration (CW) of additives. However, reduction rate was more dominating in the case of 0.4 (% by weight) of the additives. Results reveals that additive of above manner provides a suitable and alternate arrangement for transportation of fine particles slurry suspension through pipeline at higher concentration.

Over the past few decades, the use of epoxy resins has gained significant attention from worldwide researchers due to its advantages in structural applications in various sectors like automotive, construction, and aerospace industries. This article summarizes and reviews the research on mechanical properties and toughening mechanism of epoxy composites filled with non-functionalized oxide nanoparticles. The incorporation of nanomaterials into the polymer matrix has been considered to be the most effective route to improve the mechanical properties of polymer composites. But the inherent brittle nature and cross-linking ability of epoxy makes it vulnerable to crack initiation and crack growth and limits its use in advanced structural applications. Recently, various kinds of nanofillers such as carbon nanotubes (CNTs), organic and inorganic oxide nanoparticles have attracted industrial interest due to their excellent mechanical, thermal, and electrical properties which can provide a dramatic improvement in the properties of epoxy composites but their dispersion issue, agglomeration and bundling problems deteriorate several important mechanical parameters of the epoxy composites. To date, no review article focused on the role of non-functionalized oxide nanoparticles on the improvement in mechanical properties of the reinforced epoxy composites. This review article assesses and summarizes some most recent findings on the de-agglomeration process, mechanical properties, and toughening mechanisms of epoxy nanocomposites reinforced with four types of most preferred non-functionalized oxide nanoparticles such as Al2O3, TiO2, SiO2, and ZrO2.

Aluminium alloys are widely used in the fields of electric module packaging, electronic technology, automotive body structure, wind and solar energy management, due to the advantages of high specific strength, high processability, predominantly anti-erosion, increased conductivity, eco-friendly nature and recoverability. The objective of the study is to review the previous papers on aluminium usages, application, and workability parameters. The methodology adopted for the study is to use the structure literature review technique, and the time period selected for the study is 2008–2019 from the Scopus database. The findings of the study concluded that there are various types of aluminium alloys has been used by the previous researchers, and only 6061 is least explored aluminium alloy among all of them. The future scope of the study is to investigate using distinct activating fluxes for raising penetration & to understand consequences on mechanical components & rust behaviour of TIG-welded aluminium metal welds.

Wear and friction results in a huge loss of energy around the world. The need to reduce the loss has prompted the scientific community to improve the performance of lubricants. The surge in the use of additive based lubricants emphasizes its importance in the modern tribology. It has drawn the attention of the researchers to develop a stable and efficient additive based lubricant. The aim of this paper is to review these additives and underline the methods to prepare a stable solution. Understanding their properties, mechanism and shortcomings is advantageous to figure out the application. In this paper the review of commonly used lubricant additives such as Titanium dioxide, Aluminium oxide, Zinc oxide, Copper and Copper oxide, Carbon nanotubes, Molybdenum disulphide, Tungsten disulphide and Diamond is provided. The base oil or lubricants are usually not effective enough. Lubricant additives in the form of micro and nanoparticles are widely used to enhance the performance of base oil. The additives are generally used to improve the tribological and thermal properties of the base oil or fluid. Heat dissipation rate, load carrying capacity, wear and friction properties of the base oil or fluid is ameliorated by the addition of these additive. Further, the paper also incorporates the recent progress in the use of these additives.

Supersonic Combustion ramjet or Scramjet is one of the revolutionary hypersonic innovations that use atmospheric oxygen to undergo the combustion process. For efficient combustion of the fuel different techniques are implemented in the combustor such as flame holding, fuel injection mechanism. A transverse fuel injection system is considered into which parallel fuel injection system is introduced, named as Hybrid scramjet combustor. In this paper, the influence of inlet Mach number on the performance of the hybrid combustor is analyzed. The current model is validated with an already available experimental study in the literature. Both graphical and qualitative analysis was done in the validation. The simulation results are in good agreement with the experimental study. In this study, static pressure contours shows the formation of oblique shock waves. The recirculation region is developed in the model due to the presence of parallel cavities. The temperature contours indicates the starting of combustion process. Due to the presence of strut in the parallel cavities increase the possibility of H2 injection in the combustion which improves the combustion process. The Mach number contours are studied for the different Mach numbers. The contours show the formation of an additional shock wave due to strut, as the Mach number increases the strength of the shock wave also increases. The recirculation region leads to the interaction of boundary layer and shock wave. The shear layer thickness is maximum for Mach number 3.0 and is minimum for Mach number = 2.25. The variation of static pressure for the different Mach number is covered in this paper. The static pressure values increases from the leading edge with the formation of oblique shock waves. This increase is due to the formation of reflected shock waves.

The incoming air speed is too high which leads to less residence time inside the combustor. To address this problem the present article includes cavity at the combustor wall to create recirculation zone. The recirculation zone enhances the performance of the combustor. Two separate cases has been selected, one with the wall cavity and other is without cavity. The extreme changes are visualized in the flow field contours. As in the both cases, mixing efficiency approaches towards its maximum however the mixing length are seen to be different. It is observed that combustion efficiency is majorly influenced by the mixing of fuel with air. It is seen from this work that the generated shock waves play a dominant role for having efficient combustion. The hydrogen speed is varied in this work for 1 and 1.25 Mach numbers and it is observed that with shock strength, the combustion efficiency increases.

The development of the scramjet engine is one of the most promising technologies of the 21st century. Researchers around the globe are making constant efforts to understand the physics and combustion characteristics of the supersonic flow in the combustor. In this paper, a computational approach has been implemented to investigate the flame characteristics of a cavity-based hydrogen-fuelled supersonic combustor for Mach numbers such as 2.25, 2.52 and 2.75 by using Ansys 14-FLUENT code. Two-equation standard K-e turbulence model and the two dimensional compressible Reynolds Averaged Navier Stokes (RANS) have been used to carry out the simulations for the cavity based supersonic combustor. Concurrently, the validation for the present work is performed in accordance with an available experimental study already done in the literature. The results are in good agreement with the experimental results. This study attempts to understand the combustion characteristics by variation of Mach number and pressure. The results for the present study show an optimal Mach number range for which there is efficient combustion in the considered combustor. Besides, the results indicate that as the Mach number increases, there is a change in the oblique shock waves downstream of the fuel injection. For the considered Mach number range there was an enhancement in combustion which in turn enhances the performance of the scramjet combustor.

Two dimensional computational model has been chosen to perform the numerical investigation of mixing performance by introducing innovative transverse fuel injector in parallel fuel injection based supersonic combustor. The Transverse fuel injector is placed 10 mm ahead of wedge shaped strut. The wedge shaped strut is used for parallel fuel injection. Hydrogen is selected as a fuel to generate thrust. The mixing between hydrogen and air have been started earlier in parallel with transverse fuel injector, nonetheless the combustion between fuel and air is started prior to parallel fuel injector. However the combustion efficiency is observed to be less.

The Gd2O3 nanophosphors codoped with Yb3+/Tm3+ and Yb3+/Tm3+/Li+ ions have been successfully synthesized by conventional solid-state reaction method. Upon 980 nm laser diode excitation, the upconversion emission spectra of the synthesized phosphors have been recorded. The observed spectra show intense blue bands at ∼ 477 nm, ∼ 489 nm and one red band at ∼ 656 nm, which are assigned to 1G4(a) → 3H6, 1G4(b) → 3H6 and 1G4(b) →3F4 transitions of Tm3+ ion respectively. The absorption spectrum of the prepared phosphor has been recorded using UV–Vis-NIR spectrophotometer. The mechanism involved in UC emission process have been analysed with help of energy level diagram and pump power study. Moreover, the CIE colour coordinates of synthesized phosphors lies in blue region which indicates that the prepared phosphors have potential applications in NIR to Visible upconversion and in blue LEDs.

Landing gear design is one of the prime and the most complex aspects of the design of an airplane. Landing gear is composed of various components which make it a complex system to design. Shock absorber is one of the important components that has to be designed such that it can absorb maximum of the kinetic energy during adverse conditions like impact landing and taxiing though bumps without any failure. This paper basically comprises structural analysis of a landing gear shock absorber model in static condition. A conventional shock absorber model is designed by using CAD software CATIA and then structural safety in static condition is analysed by using ANSYS. In this work, large commercial aircraft Boeing 787-8 is taken as problem field. Titanium alloy and High strength Stainless Steel two different materials are chosen for the analysis to check the behavior of stress and compare the strength of the model for both the materials. The result shows that the model of high strength stainless steel has lesser stress and deformation.

The present work is focused on the outcome of ZrO2 nanoparticle content variation over viscoelastic, mechanical and thermal properties of epoxy resin. For this, ZrO2–epoxy nanocomposites were prepared using ultrasonic dual mixing technique that consists of simultaneous employing ultrasonic mixing with a rotating impeller. For dynamic mechanical analyses (DMA), a single cantilever mode measurement was performed on neat as well as ZrO2–epoxy nanocomposites to determine the storage modulus, tanδ value and glass transition temperature. Cross-linking density in the rubbery region of composite materials was also identified by DMA analyses. Tensile properties of prepared nanocomposites were measured using universal tensile machine. 4 wt.% ZrO2–epoxy nanocomposite material gives maximum enhancement in storage modulus and tensile strength about 70 and 34% as compared to neat epoxy. Thermal gravimetric analysis (TGA) revealed the improved thermal stability of ZrO2–epoxy composite materials. The uniformity of ZrO2 nanoparticles distribution in epoxy matrix was examined using field emission scanning electron microscopy (FESEM).

Swept-source optical coherence tomography (SSOCT) is a noncontact, noninvasive bioimaging tool that uses various probes to obtain high contrast images. Rare-earth based upconversion particles (UCPs...

The aim of the current study is to demonstrate the potential of rare earth (RE) based upconversion nanoparticles (UCNPs) as molecular probing agents for non-invasive depth-resolved bioimaging technique, swept-source optical coherence tomography (SSOCT). The Na+ doped La2O3:Er3+/Yb3+ UCNPs were synthesized using a solution combustion route with characterization for emission spectra and morphological study. A custom made SSOCT system was also incorporated for tissue imaging with an A-scan rate of 100 kHz/s, the central wavelength of 1060 nm, an axial and lateral resolution of ~ 4.5 µm and ~ 13 µm in tissue, respectively. UCNPs are utilized as exogenous molecular probing agents to improve local scattering in inner tissue layers. In vitro imaging of chicken breast tissue is functioned with and without excited UCNPs. Time-dependent dynamic changes in scattering coefficients of local tissue and contrast to noise ratio (OCT B-scans) is presented with a new mathematical model. Substantial enhancement in OCT image contrast, local scattering coefficients, and depth range of OCT was observed. The penetration dynamics of excited and non-excited UCNPs with time is reported. Excitation of the UCNPs enhance the scattering coefficients which lead to high contrast OCT images. It also enables the tunable characteristics of UCNPs as targeted molecular probes.

This study was performed with an objective of developing and validating an UV-spectroscopic method for estimating contents of prulifloxacin in simulated intestinal fluid (SIF) i.e. phosphate- buffer media with a pH of 6.8 as per ICH guidelines. The λmax for prulifloxacin in phosphate- buffer media pH 6.8 was found to be 272 nanometer. The calibration curve of drug followed linearity in-between 1-9 μg/ml concentration range and correlation co-efficient value was found equal to 0.9995. We tested this proposed method onto the bulk and marketed pharmaceutical formulation (tablets) also in order to find out contents of drug. Using developed method for estimation of prulifloxacin in SIF, drug was found to be in-between 101.91 and 104.02 % in marketed tablets which shows a good agreement with that of the claimed level. Accuracy of developed method was established through recovery experimentation, performed for three spiked percent concentrations- 75%, 100%, and 125%. The % recovery was found to be in between 97.27 and 101.82%. Low values of % RSD supported accuracy as well as the reproducibility of developed method. Precision of developed method was established by good in-limit intraday and interday experimental variations and through repeatability tests. Values of % RSD less than 2 confirmed about precision of developed method. The ruggedness of the developed method was validated by performing drug estimation by two different performers. This proposed spectroscopic method has proved to be a rapid and successful method for routine analysis of prulifloxacin in simulated intestinal fluid.

Vertical axis wind turbine (VAWT) is an economic and widely used energy converter for converting wind energy into useful form of energy, like mechanical and electrical energy. For efficient...

This paper audits the ongoing developments in the field of thermal energy storage based on PCM and comparison of their different properties. Solar energy is bounteously accessible and can be stored utilizing PCMs to counter the increasing demand of this era. There are different types of PCMs available for the same. Main disadvantage with the organic PCM is their poor conductivity. By using nanofluids it is found that the conductivity for paraffin wax may be improved as discussed in this article. Discharge using nanofluid is not so beneficiary because it reduces the time of discharging which is generally not required therefore it is advised to use nanofluid for charging purpose and simple water for discharging purpose to obtain maximum efficiency of the system.

This paper deals with experimental study conducted on slurry erosion pot tester to examine the effect of different parameters on erosion wear. Bottom ash is taken as the erodent material with varying concentration. The Taguchi’s approach with L9 (32) orthogonal array is used to assess test data. By using the Taguchi’s DOE (Design of Experimentation) influence of test parameters such as rotational speed (N), solid concentration (CW) and testing time duration (T) on erosion wear could be estimated by computing signal-to-noise ratio and analysis of variance. From analysis of test results, erosion wear in brass has been found in order of N > CW > (T). Based on experimental data it is clearly revealed that erosion wear have strong dependence on parameters like N, CW and T.

The objective of present research work is to investigate the combustion flame acceleration and performance of pulse detonation engine (PDE). The PDE tube consisting of obstacles of varying gap with fixed blockage ratio is analyzed in the current study. The three-dimensional reactive Navier–Stokes equation along with realizable k–e turbulence model is used to simulate the combustion phenomena of hydrogen–air mixture. The one-step irreversible chemical kinetics model analyzes detailed mechanism of exothermic reaction. The propagation of flame and deflagration-to-detonation transition (DDT) run-up length is based on normal propagating regime. As the gap between combustor inner surface and obstacle outer diameter increases, the propagating area near the combustor axis reduces. Therefore, loss of momentum of turbulence combustion particle and unburnt fuel particles (voids) are increased at the wake of obstacle due to the increase in gap (or reduction in obstacle outer diameter), which results reduction in detonation wave velocity and detonation total pressure. However, DDT flame run-up length increases with lower temperature along the axis of PDE combustor. The thrust force generated by PDE combustor also gets reduced as the obstacle diameter is reduced.

The objective of the present analysis is to investigate the effect of gaseous hydrocarbon fuels, such as Octane C8H18, Hexane C6H14, and Pentane C5H12 on the cyclic combustion process in an obstructed channel of the pulse detonation engine. Three-dimensional reactive Navier-Stokes equations are used to simulate the combustion mechanism of stoichiometric hydrocarbon fuels along with a one-step reaction model. The fuel is injected at atmospheric pressure and temperature and is ignited with pre-heated air. The investigation shows that initially a high-temperature combustion wave propagates with the local speed of sound; it creates turbulence after colliding with obstacles, resulting in an increase to supersonic flame speeds. Therefore, different values of the combustion flame propagation speed, combustion efficiency and impulse per unit area are obtained for these fuels. The detonation speed in the hexane-air mixture is about 5.8% lower than the detonation speed predicted by the NASA CEA400 code. However, it is observed that the octane fuel reduces the deflagration-to-detonation transition run-up distance as compared to other fuels.

The literature review reveals that the supersonic combustion wave remains a helpful method for improving the efficiency of pulse detonation engines (PDEs). A number of experimental studies have been conducted on detonation waves, which are formed by deflagration-to-detonation (DDT) transition waves. In this work, a straight PDE tube with a length of 1200 mm and a circular cross section measuring 60 mm in diameter is considered for combustion analysis. The combustion mechanism of stoichiometric hydrogen-air mixture is modeled by a three-dimensional Navier-Stokes turbulence model with a one-step reduced chemical kinetic reaction model using ANSYS Fluent software. The detonation tube contains obstacles with various blockage ratios of 0.5, 0.6 and 0.7 with 60 mm spacing (S) between them. Initial boundary conditions of 0.1 MPa pressure and 293 K temperature are applied to the hydrogen-air mixture to initiate combustion. The objective of the present work is to analyze the combustion flame generation and development of a stable detonation wave in the PDE tube. The flame rapidly develops and accelerates due to the burning of unburnt fuel particles in the leading zone and reduces the DDT run-up length.

Herein Ho3+/Yb3+ doped GdF3 phosphor was prepared by chemical coprecipitation method. Further, during sample preparation, Ag+ ions were incorporated into the GdF3 lattice to enhance the upconversion emission. Using 980 nm excitation intense emission bands were observed at 543 nm and 650 nm corresponding to the 5F4→ 5I8 and 5F5→5I8 transitions. Incorporation of Ag+ ions has resulted in enhancement in the emission and maximum intensity was obtained for the Ag+ concentration of 10 mol%. It was supposed that Ag+ ions change the crystal field around the Ho3+ ions that result in emission enhancement. The Ag+ incorporation was also confirmed through UV–vis absorption and downconversion analysis. The effect of the magnetic field was studied on the emission intensity and an optical hysteresis loop was observed in the plot of emission intensity vs the magnetic field. The CIE color coordinate variation based temperature sensing ability of the optimized sample is also demonstrated.

The nanofluids may be considered as multifaceted fluids, generally employed to improve the effectiveness of thermal systems, though poor stability due to sedimentation and agglomeration has limited their applications in practical use. In this work, commercial Al2O3 nanopowders were dispersed in distilled water using CTAB as surfactant. Stable Al2O3 /water nanofluids with weight concentrations ranging from 0.02–0.5 wt% were synthesized using bath and probe ultrasonication. Nanopowders were characterized using high-resolution TEM micrography. UV–Vis spectroscopy and zeta potential tests were also conducted to check stability of the nanofluids.

Tungsten Inert Gas (TIG) arcing is a widely accepted process used in several industrial applications of welding and surface modification. The selection of optimized TIG arcing parameters plays a critical role in obtaining the desired properties of the weld joints and the modified surface. The current investigation proposes a finite element simulation model for the TIG arcing process intending to predict the thermal characteristics and residual stresses for AISI 4340 structural steel. An independent model was developed for the prediction for a profile of the weld bead, independent from any empirical parameter. The TIG arcing process introduces concentrated heat input to the material which may cause the temperature to rise more than the melting point in the fusion zone and cause microstructural phase transformation in the material and considered in the Finite Element (FE) model. The model has been validated on AISI 4340 steel plates. However, the model can be applied to other materials because it is dependent only on material properties. The residual stress analysis has also been done through the model and validated with the experimental method.

Transportation of solids through slurry transportation system is very effective and efficient method SS 430 is the preferred material for pump impeller on account of its superior corrosion and erosion wear resistance properties, however its hardness is not as high as the other materials used for making impellers. On account of the paper deals with erosion related wear effects on SS 430 and SS SD 2507 samples has been evaluated by performing experiment on slurry pot tester. Experiment was conducted on two parameters namely, rotational speed and different particle size of the erodent material. Fly ash was taken as the erodent material and experiments were performed for rotational speed of 700, 950, 1200 and 1450 rpm. Particle size of the fly ash varies from 53-75 µm, 75-110 µm, 110-150 µm and 150-180 µm. Results shows the SS SD 2507 having higher micro hardness as compared to SS 430 and because of this SS SD 2507 shows better erosion wear resistance as compared to SS 430. So use of SS SD 2507 as pump impeller is advised from impeller longevity stand point in comparison to SS 430 impeller.

An asymmetric blade vertical-axis wind turbine (VAWT) is one of the emerging technologies for harvesting power in the built environment, which has low wind speed. Although asymmetric blade improves VAWT’s performance, the effect of blade pitch angle on its design is hardly ascertained. In this paper, unsteady 2D Reynolds-averaged Navier–Stokes CFD simulations are carried out to investigate the effect of blade pitch angle on the aerodynamic performance of a NACA 63-415 asymmetric blade H-Darrieus VAWT at a low wind speed of 6.0 m/s. Its detailed flow physics at different operating and pitch angle conditions is investigated, and important performance insights are obtained to elucidate its desired blade pitch for performance improvement. The present study shows that positive pitch angle (+ 5°) improves the turbine performance in upwind position, whereas negative pitch angle (− 5°) augments the turbine performance in downwind position as well as causes less wake effect than positive pitch angle. Further, optimal pitch angle (+ 5°) is found out at which the maximum power coefficient of 0.271 is obtained for an operating tip speed ratio 2.4. The present study delineates how desired blade pitch improves the performance of asymmetric blade VAWT for sustainable power generation in the built environment.

In the present work, static settled concentration, pH and viscosity of bottom ash is studied with addition of additive. Sodium sulfate is used as an additive with proportion of 0.2, 0.4 and 0.6% (by weight). The solid concentration of bottom ash suspension varied from 20 to 50% (by weight). Remarkable improvement has been observed in static settled concentration, pH and viscosity with addition of sodium sulfate with proportion of 0.4%. Reduction in relative viscosity is highly pronounced at higher solid concentration. Similar observation has been reported for static settled concentration and pH of slurry suspension. Addition of additive in bottom ash suspension improves the rheological characteristics which can be beneficial for conveying bottom ash slurry suspension at higher concentration.

Purpose This paper aims at erosion wear experimentation conducted on two piping materials, namely SS202 and SS304 to establish the effect of rotational speed, concentration and time period. Design/methodology/approach Erosion wear because of slurry flow is investigated using a slurry erosion pot tester. Fly ash is taken as erodent material having different solid concentrations lie in range 30 to 60per cent (by weight). Experiments are performed at four different speeds, i.e. 600; 900; 1,200; and 1,500 rpm for time duration of 90, 120, 150 and 180 min, respectively. To enhance erosion wear resistance of both piping materials, high-velocity-oxy-fuel coating technique is used to deposit WC-10Co4Cr coating. The parametric influence of erosion wear is optimized using Taguchi method. Findings The results show that significant improvement in erosion wear resistance is observed by deposition of WC-10Co4Cr coating. It is observed that rotational speed is found as highly influencing parameter followed by concentration and time duration. Parametric investigation of erosion wear is helpful to develop a procedure for minimizing the erosion wear in pipeline for the flow of solid-liquid mixture. Originality/value Slurry erosion wear of WC-10Co4Cr coated stainless steel (SS202 and SS304) is substantiated by extensive microstructural analysis and optimization technique.

In this article upconversion luminescence of silver nanoparticles (AgNPs) coated NaYF4:Er3+/Yb3+ phosphor nano-particles was investigated. The prepared samples were characterized through various techniques. The surface plasmon band is observed for prepared AgNPs by analyzing UV-vis measurements and is used to enhance the upconversion emission. From the upconversion measurement the emission bands are observed at 522, 546, and 656 nm corresponding to the 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 levels, respectively. The upconversion emission intensity of the above bands is found to enhance for sample containing 1 mmol AgNPs. Decay time of 4S3/2 and 4F9/2 levels is found to decrease on coating of AgNPs and hence intensity enhancement is assumed due to the surface plasmon resonance (SPR) effect.

This work describes the synthesis, structural and optical properties of Tm3+/Yb3 doped and Ca2+ co-doped YF3 upconversion phosphor material. The effect of Ca2+ ions co-dopant concentration is varied at 0, 10, 20 and 30 mol% to observe it’s effect on YF3:Tm3+/Yb3+ through different characterizations like XRD, XPS, FE-SEM, FTIR, UV–vis and upconversion measurements. Dominant upconversion emission bands are found at 450, 476, 645 and 696 nm emission wavelengths corresponding to the 1D2→3F4, 1G4→3H6, 1G4→3F4 and 3F3→3H6 transitions within Tm3+ activator center on 976 nm excitation. Finally, prepared samples are utilized in temperature sensing application demonstrations with Ca2+ ions co-dopants concentration variations.

In this work, the characteristics of the lap shear joints of MWCNT-epoxy adhesive on mild steel adherend are investigated. In this paper, multiwall carbon nanotubes (MWCNTs) are homogeneously and cluster-freely reinforced in epoxy matrix by simultaneously applying ultrasonic waves and an axial flow impeller on epoxy resin to develop toughened epoxy adhesives. Here, we describe details pertaining to mild steel surface morphology, the bond line thickness of the adhesive, the wettability of MWCNT-epoxy resin on the mild steel surface and the impact of the presence of MWCNTs in epoxy resin on the performance of lap shear joints. The experimental observations indicate that the reinforcement of MWCNTs in epoxy with uniform cluster-free dispersion and a change in the morphology of the mild steel adherend significantly improve the strength of lap shear joints and change their failure mode. The inclusion of 0.75 wt% of MWCNTs in epoxy adhesive resulted in the largest enhancement in the lap shear strength and as the weight percentage of MWCNTs increased from 0.75 wt%, the lap shear strength began to degrade.

Herein, enhancement of upconversion emission and temperature sensing in Li+/Mg2+ co-doped Gd2Mo3O9: Er3+/Yb3+ is reported. The upconversion emission enhancement of 53 and 21 times is observed in green (524 nm) and red (660 nm) emission bands via simultaneous co-doping of Li+/Mg2+ ions and is explained in terms of radiative and non-radiative transition rates. High thermal sensitivity of the material is realized upon Li+/Mg2+ co-doping by measuring the fluorescence intensity ratio of two thermally coupled energy levels (2H11/2 & 4S3/2) of Er3+ ion. The maximum absolute sensitivity of 0.0230 K−1 at 513 K is found for present material and is among the highest measured sensitivities for luminescence based thermometers. Additionally, improved magnetization and magnetic mass susceptibility is also observed on co-doping of Li+/Mg2+ in the material. The result suggests that simultaneous incorporation of Li+/Mg2+ is an effective approach for enhancing multifunctionality of Gd2Mo3O9: Er3+/Yb3+ phosphor and this material has potential applications in colour displays, high temperature sensing and magnetic resonance imaging.

In this work, multi-walled carbon nanotubes (MWCNTs) are decorated by TiO2 nanoparticles and formed a new hybrid structure of filler (MWCNT/TiO2 hybrid filler). The MWCNT/TiO2 hybrid filler is reinforced in epoxy matrix and studied the mechanical and anti-corrosion properties of epoxy. The morphology of newly formed MWCNT/TiO2 hybrid nano filler has been studied using transmission electron microscopy (TEM). Field Emission Scanning Electron Microscope (FESEM) images of tensile fracture surface confirmed the superior dispersion of MWCNT/TiO2 in the epoxy matrix. The resultant MWCNT/TiO2 hybrid-epoxy nanocomposite exhibits superior anti-corrosion and mechanical performance than the nanocomposite produced by loading of only MWCNTs or TiO2 nanoparticles as well as neat epoxy. For example, tensile strength and storage modulus of epoxy increased by 61% and 43% respectively on loading of MWCNT/TiO2 hybrid nano filler. Furthermore, the coating of MWCNT/TiO2 hybrid-epoxy nanocomposite on mild steel reduces the corrosion rate upto 0.87×10-3MPY from 16.81MPY.

The performance comparison of two automotive air conditioning systems was experimentally studied under two typical cabin conditions viz; 27°C dry bulb temperature / 40% relative humidity and 40°C dry bulb temperature /40% relative humidity in a bench test rig for different blower speeds of the evaporator. Two mobile air conditioning systems viz; enhanced system having minichannel evaporator with integrated receiver-dryer condenser, and baseline system having conventional serpentine evaporator with parallel flow condenser were considered for the study. The compressor was the same for both the systems. The charge quantity, compressor speed, condenser air flow rate were suitably modified to maintain similar suction / discharge pressures, suction super heat and sub-cooling at all test conditions. The percentage of condensate retention during the dehumidification for both the evaporators were also compared. The comparison indicates that the average coefficient of performance of the enhanced system is h...

The photoluminescence properties of Yb3+ sensitized Er3+ doped BaLa2(MoO4)4, SrLa2(MoO4)4 and CaLa2(MoO4)4 phosphors synthesized via hydrothermal method are investigated upon 980 nm and 380 nm light excitations. The phase, purity, and morphology of the samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Field emission scanning electron microscope. Among these three phosphors, the strongest emission intensity is seen in BaLa2(MoO4)4: Er3+/Yb3+ through both the 980 nm and 380 nm light excitations and is explained by the lifetime measurement of 4S3/2 level of Er3+ ion. Temperature sensing measurements were performed by using the fluorescence intensity ratio (FIR) of green emission bands originated from the two thermally coupled 2H11/2 → 4I15/2 and 4S3//2 → 4I15/2 transitions of Er3+ and maximum temperature sensitivity of 1.05% K−1 at 305 K is found for BLa2(MoO4)4: Er3+/Yb3+ sample. Moreover, the laser induced heating is measured in the samples and the maximum temperature of the sample particles is calculated as 422 K at 76 W/cm2 in BaLa2(MoO4)4: Er3+/Yb3+, pointing out large amount of heat generation in such phosphors. The BaLa2(MoO4)4: Er3+/Yb3+ also exhibits higher photothermal conversion efficiency of 46.7%.

Fabrication of mono, hybrid and nanocomposites is becoming an emerging field nowadays. The fabricated MMCs are used in the manufacturing of aircraft, aerospace, and aeronautics due to their better mechanical and tribological properties in comparison with the traditional fiber-reinforced composites. For fabricating metal matrix composites, friction stir processing is an evolving technique. In this study, the effect of vibrations on the properties of friction stir processed alloy is reviewed. A literature review related to the wear resistance analysis of friction stir resistance analysis of friction stir processed metal matrix composite is presented.

High-performance epoxy-carbon nanotube (CNT) nanocomposites were prepared by simultaneous use of ultrasonication and mechanical stirring. The dynamic and static mechanical properties and wetting properties of the nanocomposites were investigated. The dynamic mechanical analysis presented significant enhancement in storage modulus (approximately 124%) and glass transition temperature (approximately 25.6%) of epoxy-CNT nanocomposite at an optimized concentration of the CNT (0.25 wt%) possibly due to the formation of a strong interface between the epoxy and CNT. The tensile test results showed the significant improvement in tensile strength (approximately 47%) and Young’s modulus (approximately 40%) of the epoxy-CNT (0.25 wt%) nanocomposite without significantly affecting its stiffness. The homogeneous dispersion of CNTs in the epoxy matrix resulted in the significant enhancement in the dynamic and static mechanical properties of the nanocomposites. The hydrophilic character of the neat epoxy was tuned to a highly hydrophobic one by incorporation of CNTs in it. A direct relation between the average roughness of the tensile fracture surfaces and the contact angle of the nanocomposites was identified with respect to the concentration of the CNTs. These high-performance highly hydrophobic nanocomposites have the great potential to be used as the structural and functional materials in humid environments.

Herein, we report luminescence studies on solid state route prepared SrTiO3:Yb3+/Er3+ ceramic. The SrTiO3 has been turned into a multifunctional material which is ferroelectric in nature via doping...

Authors here report the dual mode photo luminescence emission in neodymium doped yttrium oxide ceramic phosphor upon 808 nm diode laser excitation. Single cubic phase Nd 3+ doped Y 2 O 3 phosphor was synthesized using urea assisted combustion route. Nd 3+ doped Y 2 O 3 ceramic phosphor has given photoluminescence in a wide wavelength range covering near infrared window (850–1100 nm) to the visible region i.e. green (525 nm) and red (680 nm) upon 808 nm diode laser excitation. The two most intense bands on 808 nm excitation were observed at 750 nm and 1064 nm due to the upconversion and downconversion emission processes. The sample was also tested for emission using 980 nm and intense green emission due to the trace presence of Er 3+ in the raw materials was seen in the sample. The excitation power dependent upconversion measurements have shown that transitions 4 F 9/2 → 4 I 9/2 and 4 S 3/2 → 4 I 9/2 are thermally coupled and can be used to estimate the sample temperature using Boltzmann relation.

To obtain cluster free homogeneous dispersion of carbon nanotubes in polymer matrix, variety of strategies were applied. In the present work, we report a systematic approach to obtain a superior level of dispersion of multi-walled carbon nanotubes (MWCNTs) in epoxy by applying simultaneously ultrasonic waves and shear force generated by axial flow impeller. The influence of dispersion of MWCNTs on anti-corrosion, mechanical and thermal properties of MWCNT/epoxy nanocomposite was investigated. Field Emission Scanning Electron Microscopy (FESEM) studies confirmed cluster free uniform dispersion of MWCNTs in epoxy matrix, which lead to enhanced tensile strength by 35%, toughness by 53% and storage modulus by 35% on loading of 0.75 wt% of MWCNTs in epoxy. It was found that when mild steel was coated with MWCNT/epoxy nanocomposite (0.75 wt%), the corrosion rate decreased upto 2.5 × 10 −3 MPY and protection efficiency increased upto 99.99%.

Pulse detonation engine is a new technique of supersonic wave propagation and stands for high impulsive thrust. The objective of the present investigation is to analyze the detonation wave characteristic of a hydrogen–air mixture in the pulse detonation engine (PDE) having obstacles of blockage ratio 0.5. The three-dimensional reactive Navier–Stokes equations with realizable k − ɛ turbulence model are used to simulate the propagation of combustion flame. The reaction rate of excess hydrogen and excess air is modeled by reduced single-step chemical reaction model and simulated using ANSYS software FLUENT 14.0 code. The simulation results of the shock wave overpressure, deflagration-to-detonation transition run-up distance of different flames and flame velocities are reported at initial boundary condition of 0.1 MPa pressure and 293 K temperature. It has been observed that the obstacles create turbulence in the propagating flame and form strong Mach stems of high temperature, resulting in reduction in accelerated flame run-up length. However, the normalized detonation flame run-up distance increases as the mass of fuel increases in the mixture. Thus, the performance of PDE combustor was observed 4.46% at high overpressure generated by excess fuel (ϕ = 1.3).

In this paper, erosion wear behaviour of slurry flow has been investigated using a slurry erosion pot tester. Bottom ash is taken as the erodent material with varying concentrations. To assess test data, Taguchi’s design of experimentation is used. The influence of test parameters on erosion wear could be estimated by computing signal-to-noise ratio and analysis of variance. L9 (32) orthogonal array is used for the investigation. From analysis of test results, it is determined that speed has found as the most influencing parameter on erosion wear of base material. Based on experimental data, it is clearly revealed that erosion wear has strong dependence on rotational speed (N) as well as solid concentration (CW) and testing time (T) also.

The numerical investigation of Detonation wave propagation and Deflagration-to-Detonation transition is done in straight long tube of 1200 mm length and 60 mm internal circular diameter with stoichiometric (ϕ=1) mixture of hydrogen-air at ambient pressure and temperature of 0.1 MPa and 293 K respectively. The detonation tube contains obstacles having blockage ratio (BR) 0.5, 0.6 and 0.7, and having 60 mm gap among them. The computation analysis is performed firstly on simple straight tube having no obstacle (BR=0.0) and then obstructed channel. The combustion phenomena of fuel-air mixture are modeled by one-step irreversible chemical reaction model. Three-dimensional Navier-Stokes equations along with realizable k-ɛ turbulence model are solved by the commercial computation fluid dynamics software ANSYS Fluent-14 code. The performance of pulse detonation engine (PDE) depends on blockage ratio (BR) of obstacles. The simulation results show that the initiation and propagation of flame is due to exothermic expansion of hot combustion gases. The obstacles generated turbulence at obstacle wakes, which caused to increase flame surface area. Therefore, obstacles reduced the Deflagration-to-Detonation transition (DDT) run-up length. The perturbation inside the combustor increases as increased the blockage ratio of obstacle. The PDE Simulation results of with and without obstacles were analyzed and compared with adiabatic flame temperature.