Search

This work aims to fabricate the functionally graded Inconel 825 - SS316L wall using the Cold Metal Transfer (CMT) based Wire Arc Additive Manufacturing (WAAM) process. The mechanical behavior of the fabricated wall was appraised with the help of room temperature tensile and microhardness tests on the specimens cut from Inconel 825, SS316L, and the interface regions. Fracture morphology revealed the failure of all the specimens after sufficient plastic deformation, indicating ductile fracture. A change in microhardness was observed at the interface region. The optical micrograph revealed a continuous cellular–dendritic and discontinuous cellular–dendritic region in the Inconel 825 region, whereas the SS316L region was comprised of δ ferrite in the primary austenitic (γ) dendrites. The Energy Dispersive Spectroscopy (EDS) line scans of the FGM wall revealed a gradual change in the Ni and Fe content throughout the interface, signifying a successful fabrication of the FGM.

Abrasive waterjets can process multi-layered structures but pose difficulties in producing quality cuts since MLS comprises of layers of materials with heterogeneous/homogenous properties. Stacking sequence of layers and the interface between layers influence kerf characteristics. Kerf geometry in each layer is influenced by a nonlinear structure with non-uniform energy distribution of AWJ. This paper presents a model to predict kerf geometry in a double-layered structure by considering jet characteristics, workpiece properties, jet-workpiece interaction at the layers' interface, and AWJ process parameters. Towards determining the jet's exclusive interaction with each layer, complete kerf profile (CKP) formation is analyzed by considering homogenous materials as constituent layers of Al-MS and MS-Al configurations. The model predicted results are in good agreement with experimental results. The average root mean square error of the kerf profile is less than 0.048 mm, and the mean absolute error is about 12.63% on both configurations.

The chemical, physical, thermal, and surface morphological properties of aerial root Ficus amplissima fiber (ARFAF) were studied. Chemical composition analysis of ARFAF quantified the cellulose (52...

For the past few decades innovation in construction material has grown a lot. This leads to special concrete such as self-compacting concrete, geopolymer concrete, self-healing concrete, etc. To prepare a special concrete apart from regular concreting material some sort of special materials was also needed, like mineral and chemical admixtures. Hence it is necessary to study the effect of these admixtures in cement paste and mortar before studying the same in concrete. Hence an attempt is made to study the effect of mineral and chemical admixtures in the fresh and hardened properties of cement paste and mortar. For this study ultrafine natural steatite powder is taken as mineral admixture and polycarboxylic based superplasticizer and glenium stream 2 were taken as chemical admixtures. Ultrafine natural steatite powder was used as additive to cement in various percentages like 0%, 5%, 10%, 15%, 20% and 25%. Superplasticizer and viscosity modifying admixture were taken as 1.5% and 0.5%, respectively. Then various combinations were worked out. To study the fresh property of cement paste consistency, initial setting time and miniature slump cone test were done based on the results yield stress of cement paste also calculated empirically. To study the hardened property compression test on cement mortar was done. Based on the test results it is clear that the addition of ultrafine natural steatite powder increases the water demand hence reduces the workability. On the other hand, it increases the compressive strength up to a certain limit. Adding superplasticizer increases the workability and reduces the water demand and viscosity modifying admixture reduces the bleeding and segregation effects hence increases the compressive strength.

One of the major reason people choose concrete structure is because of its durable nature. This paper brings out the experimental results on durability study of ternary blended Self compacting concrete (SCC). The minerals used in this study are fly ash (FA) - as partial replacement to cement and ultra-fine natural steatite powder (UFNSP) - as an addictive. FA is used as a partial replacement to cement in SCC at 10% and 20% by weight. In both of this replacement level UFNSP were added in various percentages like 0%, 5%, 10%, 15%, 20% and 25% by weight of powder content. Hence totally thirteen sets of specimens were casted and various durability studies like initial water absorption, saturated water absorption, effective porosity, sorptivity, rapid chloride penetration and bulk diffusion were studied. In this study the steatite and fly ash particles mainly contribute as filling material hence at higher percentage the same mitigates the voids, which is also noted in the calculation of effective porosity. This experimental investigation is further supported by the scanning electron microscope images. Increasing the replacement level, arrested the microcracks thereby improved the microstructure and showcased very less voids. The SEM images also indicated the formation of magnesium silicate hydrate gels which also contributed to the enhancement of durability properties.

Some shortages in conventional flood cooling technique under heavy cutting settings were noted while machining. Therefore, nanofluids (NF’s) that have elevated thermal conductivity than traditional...

The main goal of this paper is to investigate the effects of recycled aggregates in geopolymer pervious concrete (GPC). The usage of recycled aggregate (RA) in the construction field is getting more attention nowadays due to sustainable construction methods. In this study, natural aggregates (NA) are partially replaced with recycled aggregates such as recycled concrete aggregate and recycled brick aggregate (RBA) in geopolymer previous concrete. For preparing geopolymer, ground granulated blast furnace slag (GGBS) was used in this investigation. Activators such as 12 M sodium hydroxide and sodium silicate solutions were used to synthesize the geopolymer concrete in this investigation. The sodium silicate-to-sodium hydroxide ratio was maintained at 2.5 throughout this study. Mechanical and durability properties of GPC were determined as per Indian standards. The effects of RA in geopolymer pervious concrete were briefly investigated. It has been observed that durability properties are affected by the incorporation of recycled aggregate (RA) in geopolymer concrete. The compressive strength value of RC12 is less than that of GC12 and RB12 is less than that of RC12. The strength properties of structural beam elements were reduced due to the incorporation of recycled concrete and recycled brick aggregate in geopolymer concrete; at the same time, the reduction always lies in acceptable ranges. Validation was done using ANSYS software. This paper leads the utilization of recycled aggregates in GGBS-based GPC instant of NA at ambient curing condition.

The thermal resistance of fabrics containing silk showed a higher value in comparison with lyocell-rich blends. The water vapour permeability, absorbency and wickability of lyocell and lyocell-rich blends were found to be superior as compared to 100% silk fabrics. With respect to aesthetic comfort properties, the drape of the lyocell rich fabrics was good in comparison with 100% silk fabrics.

In this work, experiments on mechanical properties such as tensile, flexural, effects, and stiffness testing are performed on natural fiber granulated composites (NFGC) manufactured using a hybrid additive manufacturing technique. The natural fiber granulated composites are prepared using the powdered form of sugarcane, jute, ramie, banana, pineapple fiber, and seashell powder with a volume fraction of 0.8. In the hybrid additive manufacturing technique, the fused deposited modeling (FDM) machine is modified by combining with the shape deposition modeling (SDM) to print the specimens layer by layer, and the influence of the number of layers on the mechanical properties is analyzed. The results concluded that increasing the number of layers from 6 to 12 improved the mechanical properties such as tensile strength, flexural strength, impact strength, and hardness values by 40.84, 50.04, 21.55, and 20.55%, respectively. Further, a novel technique can be utilized for developing the composites in replacement with conventional methods.

This paper investigates quantum mechanical effects on surface potential and threshold voltage in a two-dimensional molybdenum disulfide (MoS $$_{2}$$ ) based transistor. Drain current improvement occurs as a result of the low work function for metal Ti and electron affinity of MoS $$_{2}$$ , thereby reducing the Schottky barrier height (SBH). The titanium (Ti) contact introduced into the mono-layer MoS $$_{2}$$ helps in obtaining lower contact resistance and improved drain current due to the lowering of SBH. An analytical model is proposed for evaluating various device parameters such as surface potential, threshold voltage, contact resistance, mobility, and drain current. This model provides useful aspects for understanding the physics of quantum mechanical effects. Compared to other conventional devices, this transistor incorporates Ti, a low work function metal, in the contact region, producing better current drive and lower contact resistance values. A positive Schottky barrier is noticed between the mono-layer MoS $$_{2}$$ and the Ti metal. Compared to other high function metals, the proposed device displayed about 11% improvement in current drive and 8% less contact resistance. By attaining an enhanced carrier injection and decreased contact resistance, this device serves as a suitable prospect for low-power applications.

This paper presents the effect of quantum confinement on the potential of short channel mono-layer molybdenum disulfide (MoS2) based transistor using Ritz Galerkin finite element technique. Unlike earlier models, only two iterations are used to obtain the potential. This model makes use of the coupled Poisson-Schrodinger equation by considering quantum mechanical effects for evaluating the potential with the support of Exciton Bohr radius, bandgap, electron energy state, Density of State (DOS), and electron concentration. Furthermore, this coupled equation along with Neumann boundary condition is employed to approximate the wave function of the Schrodinger equation, which is used again in the Poisson equation for calculating the potential. This work accurately predicts the impact of quantum confinement effects in the perpendicular direction of the channel surface.

One dimensional (1D) metal organic framework (MOF) micro/nanostructural arrays are highly promising candidates for their potential applications in energy related areas. These exceptional behaviors ...

Background: osseointegration of dental implants refers to direct structural and functional link between living bone and the surface of non-natural implants. It follows bonding up of an implant into jaw bone when bone cells fasten themselves directly onto the titanium surface.it is the most investigated area in implantology in recent times. Evidence based data revels that osseointegrated implants are predictable and highly successful. This process is relatively complex and is influenced by various factors in formation of bone neighbouring implant surface. Keywords: Osseointegration, Implant, Bone.

In this study performance evaluation of Radiator is numerically investigated with different fluids and different volume flow rates using CFD technique. Radiator 3D model is developed in SOLIDWORKS and same model is imported to ANSYS-FLUENT for further analysis. Mesh sensitivity analysis shows that 0.5 mm element size is optimum for the selected radiator model. For this study, various fluids such as pure water, water with 50% ethylene glycol, water with 0.05% concentration of Al2O3 nanoparticle, water with 0.1% concentration of Al2O3 nanoparticle and water with 0.2% concentration of Al2O3 nanoparticle are chosen as cooling fluid. Results show that, the Nusselt Number increases with the volume of rate and particle concentration. Also, the heat transfer coefficient increases with the particle concentration and volume of rate. The performance of the Nanofluid based radiator is enhanced by 10.64% and 3.82% in terms of Nusselt Number and heat transfer coefficient respectively when compared with pure water. Finally, water and ethylene glycol mixture with Al2O3 nanoparticle 0.05% concentration has better performance than remaining fluids.

The aim of the study is to develop and investigate the suitability of thermoplastic composites for underwater applications. PA6/PP/PP-g-MA (70 wt%/30 wt%/3 phr) blend is used as a novel matrix to synthesize UDCF composites with balanced strength and toughness even in humid conditions. This novel matrix has around 60% lower water absorption capacity compared to PA6. Short carbon fibres (SCF) and unidirectional carbon fibre fabric (UDCF with 12K rovings) are used as reinforcements. X-ray CT data of injection-molded SCF composites revealed good wetting. However, in the case of compression-molded UDCF composites, a few unwetted zones were found. Comparing dry and wet samples, wet-matrix, wet-SCF composite and wet-UDCF composites had 40, 15, and 25% reduction in their tensile strengths, respectively. However, the impact strength of wet-matrix and wet-UDCF composites increased by 67 and 61%, respectively. Hence, SCF composites having a wet tensile strength of 46 MPa can be used in preparing underwater components due to the low number of interfacial voids. UDCF composites having more interfacial voids are recommended for humid conditions wherein the wet impact strength (11.4 J) and wet tensile strength (266 MPa) are the main criteria.

In this paper, for sensing and monitoring the biochemical analyte dissolved in liquid, antigen-antibody interaction or protein-DNA/RNA binding process, we design a surface plasmon resonance refractive index based biosensor by using a dual core D-shaped six-fold photonic crystal fibre which is embedded with silver nanowires for multi-detection. We numerically analyze both the dispersion relations and the loss spectra for various analytes by finite element method. This optical fibre bio-sensor monitors the changes of the refractive index for different analytes by measuring the spectral shifts of the fibre loss peaks at their resonance wavelengths. With the wavelength interrogation method, we find that the proposed biosensor with two sensing channels exhibits a maximum refractive index sensitivity of 3400 nm/RIU and a resolution of $2.94\times 10^{-5}$ RIU for a large sensing range from 1.35 to 1.50, which covers most known analytes of proteins, viruses or DNA/RNA. By utilizing 200 nm silver nanowires in the sensing channels, the sensitivity can be enhanced up to 4000 nm/RIU. Due to its special two-channel design for multi-sensing, it is possible to distinguish/study the binding possibility/capability of unknown analyte with two different target proteins simultaneously. Further, by introducing another critical channel, the confinement loss for either channel I or channel II can be greatly enhanced for high accurate result and more reliable sensing. Moreover, we numerically prove that the diameter of nano silver wires has great influences on the sensing peaks and sensitivity of the proposed biosensor.

The current trend in the automobile industry is to use composite materials, which are lightweight and non-corrosive to atmospheric conditions. The present work explores the feasibility of using a pultruded composite structure for the Rear Under run Protection Device (RUPD) of a truck. Numerical simulations have been performed for analysing the impact behaviour of the RUPD which is made of composite. Impact simulations are carried out for moderately high velocity impacts of 20 km/h and 40 km/h. The impact energy absorption, peak reaction loads and displacements are compared for different pultruded composites. Results indicate that RUPD structure consisting of carbon-epoxy bidirectional mat at outer layers and unidirectional mat as inner core layer provides more specific energy absorption and less reaction loads. The simulation results presented in this study will provide guidelines for designing the composite RUPD structure.

Effect of harmful emission like oxides of nitrogen (NOx) and smoke (or) particulate matter (PM) from automobile vehicles to the environment become an addressable topic nowadays. In general NOx and smoke levels are slightly higher in diesel engine compared to petrol engine due to excess Oxygen (O2) supply, high in-cylinder temperature & improper mixing (Heterogeneous mixture) of fuel & air. These emissions are normally controlling by either combustion or by after treatment process. To control these emissions in after treatment process, three-way catalytic converter coated with noble materials like platinum, palladium & rhodium is used in diesel as well as petrol engines. In this present work, various emission characteristics were studied in single cylinder, water cooled, four stroke direct injection diesel engine with and without silver & zinc coated catalytic converter. Experimental results shown that diesel engine with silver (Ag) & zinc (Zn) coated catalytic converter provide 70% of reduction in NOx, 60% of reduction in CO, 55% of reduction in HC and 40% of reduction in CO2 emissions respectively at the exhaust pipe in full load condition compared with conventional diesel engine.

This research paper presents the machinability of ground-granulated blast furnace slag (GGBS) which is reinforced with aluminum 6061 metal matrix composites using electrochemical micromachining (EMM). EMM process is the most prominently utilized machining process in various fields of micro fabrications in aerospace technology, automobile and other industrial applications. In this research a central composite design was adopted while designing the experiments. Temperature of the electrode, voltage, electrolyte concentration and percentage composition of reinforcement (6%, 9% and12% GGBS) are chosen as the input machining parameters. Radial overcut (ROC) and material removal rate (MRR) are considered as response parameters. Additionally, multi criterion decision making namely grey relational analysis (GRA) is utilized to find out the optimal input parameters. From GRA, the optimal parameters are 40⁰C, 12 V, 25 g/l and 9% of GGBS composition.

The aim of this study is to analyze various ways to increase the performance of Thermoelectric (TEG) by using Computational Fluid Dynamics (CFD) techniques. For this study a three-dimensional model of TEG is developed using design modeling software SOLIDWORKS and the developed geometry is exported to CFD package which is ANSYS-FLUENT for further analysis. Mass flow rate of exhaust gas is 0.279 kg/s at a temperature of 800 K and mass flow rate of the coolant is 0.26Kg/s at a temperature 350 K are taken as boundary conditions. For this analysis various parameters are investigated such as heat exchanger material, inclination and exit gap of heat deflector and use of baffles. The effect of heat exchanger material on the performance of TEG is investigated. For this investigation pure copper, pure aluminum, aluminum alloy and low-carbon steel are chosen as heat exchanger material. Results show that pure copper has given better performance than others with 184.98 K of temperature difference. To study the effect of exit gap between heat deflector and exhaust pipe on TEG performance, exit gap is varied from 10 mm to 15 mm with an increment of 2.5 mm. The inclination angle of heat deflector is varied from 1° to 3.5° with an increment of 0.5°. Results show that 2°inclination angle of deflector with 10 mm exit gap has given better performance than other inclinations and exit gaps. The influence of baffles on TEG performance is also studied. Introducing a baffle in inclined position directs the flow direction of exhaust gas effectively to achieve better heat distribution. Finally, it can be concluded TEG has good performance with copper material as heat exchanger material, 2° inclination angle of deflector and 10 mm exit gap between heat deflector to the exhaust pipe.

In this paper, we mainly investigate the sensing performance of a fabricable 6-fold D-shaped photonic crystal fibre sensor based on the surface plasmon resonance (SPR). Its resonance couplings between fundamental core mode and three surface plasmonic modes which have different electric filed distributions for analytes of various refractive indices have been studied in detail. We firstly observe two different types of SPRs, namely, ‘dielectric like’ resonance with low-loss peak and ‘plasmon like’ resonance with high-loss peak, by analysing the electric field distribution of the fibre modes. Then, we discuss the influence of the secondary SPR over the main SPR which is directly related to the limitation on the detection sensing range of the proposed sensor. In order to mitigate the adverse effect of the sub-peak of the secondary SPR on the sensor’s sensing performance, we reduce the thickness of analyte’s binding layer from 1500 nm to 500 nm. Thus, the sensing range of the proposed sensor can be tuned from 1.33 – 1.41 to 1.33 – 1.45 at the cost of a reduced maximum sensitivity from 7900 nm/RIU to 5300 nm/RIU. Owning to the simple structure design of the proposed sensor, we envisage that this highly sensitive D-shaped PCF-SPR sensor could be developed as a versatile and competitive instrument with a large and flexible refractive index detection range.

Composite materials have high strength to weight ratio with low density and high stiffness to weight, high strength ratios, and high fatigue strength to weight ratio compared to traditional engineering materials making them find wide applications in structural constructions. When the lightweight composite materials which are made of lightweight natural fibres are used in automotive application, the fuel economy of the vehicle improves reducing the related harmful emissions. The aim of this research is to develop and characterize the performance of sisal and bamboo reinforced polyester hybrid composite (BSFRHC) with different fibre orientation of sisal and unidirectional (UD) bamboo fibre. Next, BSFRHC was fabricated with 20% total fibre volume fraction. Of this total fibre volume, the composite is fabricated in 3:1 bamboo to sisal fibre ratio using hand lay-up technique. Then tensile, compressive, impact and flexural tests were carried out. In general, it is concluded that as varying fiber orientation, the tensile strength varies. The higher tensile strength is observed with 0° fibre orientation of bamboo/sisal fiber reinforced hybrid composite. From compressive strength of the hybrid composite reinforced with bamboo/sisal fibre, it is observed that the 0°-fibre orientation composite is exhibiting higher compressive strength than 90° fibre orientation composite and bidirectional (0°/90°) fibre orientation composite. Unidirectional 90° fibre orientation was found to have a higher tensile and flexural strength whereas unidirectional 90° and bidirectional (0°/90°) fibre orientation nearly have the same value of tensile strength, whereas bidirectional (0°/90°) was found to be having higher flexural strength than unidirectional 90° fibre orientation. Impact analysis of vehicle internal door panel made of BSFRHC was done using ANSYS Software. Furthermore, it is found that the bamboo and sisal fibre reinforced hybrid composite in unidirectional 0° has the potential to be used for automotive interior part application.

In the present work, stability lobe diagrams for high speed milling are generated by the application of Operational Modal Analysis (OMA) technique during machining operation at different spindle speeds. The vibration signals are acquired by laser vibrometer during milling operation. To make the vibration signals feasible for OMA, a new approach is proposed to excite the milling cutter by white noise excitation. Specific cutting force coefficients are also estimated at different spindle speeds. The effect of variation of spindle speed on the dynamic parameters and specific cutting force coefficients is considered in the present work. With the application of the estimated specific cutting force coefficients and dynamic parameters, stability lobe diagrams are drawn at different spindle speeds. A comparative study of stability lobe diagrams, generated at different spindle speeds is also performed and the accuracy of these diagrams is presented.

In this paper, an analytical approach to predict the bend angle of sheet formed with multiple laser scans is proposed. The proposed approach considers the temperature dependent properties of the sheet material to evaluate the temperature profile across the thickness of sheet Based on this temperature profile, the strain energy stored in the laser irradiated area is estimated and the same is utilized to determine the final bend angle. To validate the feasibility of the proposed model, experiments were performed on AISI 304 steel sheet with different processing conditions and the predicted bend angle is compared with the experimental result. Finally, the effect of process parameters on the laser formed sheet is discussed.

Sisal fiber composites became attractive due to their high specific strength, lightweight and biodegradability. The aim of this work is to examine characteristics of sisal fiber as composite material for light body vehicles on experimental basis. Composite materials prepared using biodegradable natural fibers are found to be most promising materials which can be used in vehicle body which results in reduction of overall weight of the vehicle. In this work sisal fiber was used. Sisal fiber was extracted using knife from the sisal plant leaves collected from Ethiopian highland. To remove cellulosic matter and improve surface roughness of the sisal fiber, it was immersed in sodium hydroxide solution for 24 h. The specimen of composite material is prepared using the general purpose resin as a matrix, the hardener and the sisal fiber as a reinforcement material with the fiber orientation of 00, ± 450, 00 & 900 by using experimental (hand layup fabrication technique). The specimen was prepared and tested as per ECAE and ASTM standard. From the test results it was found that sisal fiber composite is a good light weight replacement for conventional materials in vehicle body applications. From the experiment result it was observed that different orientation of fiber has shown enhanced mechanical properties of the sisal fiber composite material.

The paper investigates the role of complete velocity slip on the axisymmetric peristaltic transport of Ellis fluid through a uniform flexible tube considering the long wavelength and tiny Reynolds number assumptions. The equations governing the axisymmetric flow are solved and provided the analytical expressions for axial velocity, stream function, pressure difference for shear thickening and shear thinning fluids and the effect of emerging parameters on the pressure rise with time averaged flux and stream line patterns have been discussed graphically. The trapping phenomenon results showed that the size of trapping bolus enhances with increasing values of first and second slip parameters.

Abrasive waterjet technology is favored over solid cutting tools for cutting of multi-layered structures in view of its non-contact nature and its ability to cut a wide range of materials. However, the stochastic nature of abrasive water jet (AWJ) interacting with a multi-layered structure (MLS) produces a non-uniform kerf geometry. This non-uniformity depends on the characteristics of jet i.e. jet energy, the duration of interaction of jet with the material, and the nature of material exposed to the jet during cutting. This paper attempts to cover a study that systematically analyses the geometry of kerf generated in MLS and a stack of multiple materials with each material having different mechanical properties. It also covers a study to analyse the role of interfacial adhesive layer on kerf profile variation, and the preferential orientation of multi-layered structure and stacked materials, with its top layer, having an appropriate mechanical resistance (MR), in order to arrive at a strategy to present the structure or a stack of materials to AWJs for producing near uniform kerf profile. Hence, AWJ cutting experiments were carried out over a single- and double- layered structures (SLSs, DLSs) with two different materials such as aluminum (Al), mild steel (MS), which showed a completely different kerf geometry when these materials are stacked in different ways. Stacking of these materials in different ways produced kerf of different geometry not only in the materials but also at their interface. This systematic study enabled to suggest the correct presentation of MLS and also a stack of multiple materials with a suitable material in top layer, to AWJ, for producing near uniform kerf in them. Further, this study also suggested several hypotheses like the importance of relative MR of adjoining layers, critical jet traverse rate, pseudo focusing nozzle, and the choice of layer placement in producing near uniform kerf on MLS and a stack of materials, so as to minimize the efforts in post machining of AWJ cut surfaces. Finally, the relevance of the proposed hypotheses was validated by analyzing the kerf formed over MS-rubber-MS and rubber-MS-rubber configured three-layered structure.

The primary objective of this research is to study the bearing performance characteristics having different operating conditions. Experimental investigations are carried out on phosphorous bronze h...

Al composites have got major attention in the research environment with its durability in industrial applications. This work deals with the addition of nano-silica into the Al6061 matrix and an inv...

The dc characteristics of AlGaN/gallium nitride (GaN) metal–oxide–semiconductor-high electron mobility transistor (MOS-HEMT) with an AlInN back-barrier layer has been studied here. An analytical model is proposed for evaluating the charge density ( $\sigma _{{\mathrm {tot}}}$ ), carrier concentration ( ${n}_{{\mathrm {S}}}$ ), drain current ( ${I}_{{\mathrm {D}}}$ ), and transconductance ( ${g}_{{\mathrm {m}}}$ ) of the device by incorporating Hafnium oxide (HfO2) as a high- ${k}$ dielectric layer. The charges created between the oxide and the AlGaN barrier layer influence the enhancement of carrier concentration of up to $6.2\times 10 ^{13}$ cm $^{-2}$ , at the two-dimensional electron gas (2DEG). The AlInN back-barrier increases the conduction band (CB) level of the GaN buffer and eliminates the confinement problems near the channel. By deriving the mathematical dependence of these parameters, this device demonstrated a positive threshold shift and a high current drive of 880 mA/mm. Cubic spline interpolation (CSI) technique is employed here to model the parameters in a more precise manner. The outcomes are evidence that the device could be a potential solution for high power switching as well as microwave applications.

The crystal structure and magnetic, electronic, and thermal properties of a NdSbTe single crystal were examined by X-ray diffraction, magnetic and specific heat Cp(T) measurements, and density func...

In the present research work, a detailed evaluation of dissimilar friction welded joints between the hot rolled ASTM A106 Grade B (carbon steel) pipes and hot rolled AISI 4140 (low alloy steel) pipes in the as-received (AR) condition and quenched and tempered (QT) condition has been carried out. All the specimens were subjected to stress relief annealing after welding. Optical and scanning electron microscopy on the AISI 4140 steel side revealed dynamically recrystallized grains, consisting of a mixture of ferrite and martensite in the friction welded AR-condition joints and mixture of ferrite and tempered martensite in the friction welded QT-condition joints. On the ASTM A 106 Grade B steel side the material showed ferrite and pearlite microstructure. SEM analysis did not reveal any intermixing between AISI 4140 and ASTM A106 Grade B steels at the weld interface in both the conditions. The region adjacent to the weld interface on AISI 4140 steel side consistently showed higher hardness in the QT-condition compared to AR-condition due to the presence of fine-grained microstructure in QT-condition. The dissimilar welded pipe joints in the present study have shown slightly higher tensile properties than that of ASTM A106 Grade B steel but significantly lower than that of AISI 4140 steel. The friction welded dissimilar pipe joint specimens have shown substantially lower impact toughness values compared to either ASTM A 106 Grade B steel or AISI 4140 steel in both AR and QT-conditions due to the presence of carbides at the weld interface.

Template/surfactant-free ZnO nanoparticles were synthesized by hydrothermal process at 120 °C, 150 °C, 180 °C and 210 °C for 3-h duration and were annealed at 400 °C for 3 h. Since the ZnO nanoparticles synthesized at 150 °C for 3 h and annealed at 400 °C for 3 h showed improved photocatalytic activities, the ZnO nanoparticles were further synthesized at 150 °C for 6-h, 9-h, and 12-h durations and were annealed at 400 °C for 3 h. All the synthesized ZnO nanoparticles were characterized for their structural, optical, and morphological properties. X-ray diffraction analysis confirmed that the ZnO nanoparticles belong to the hexagonal wurtzite system. Transmission electron microscopy and high-resolution transmission electron microscopy analyses revealed that the hydrothermally synthesized ZnO nanoparticles at 150 °C for 3 h and annealed at 400 °C for 3 h acquired spherical and hexagonal morphologies with size ~ 50 nm. Variation in the hydrothermal temperatures and time durations with annealing at 400 °C for 3 h acquired nearly hexagonal, spheroidal, and hexagonal morphology of the ZnO nanoparticles. Optical band gap of synthesized ZnO nanoparticles was slightly influenced by the different synthesis parameters. The photocurrent measurements revealed that the ZnO nanoparticles synthesized at 150 °C for 3 h and annealed at 400 °C for 3 h possess relatively enhanced of photocurrent of about 3.58 μA than that of the other synthesized samples. The ZnO nanoparticles synthesized at 150 °C for 3 h and annealed at 400 °C for 3 h showed ~ 78% and 36% of photodegradation efficiency against Rhodamine B dye and 4-chlorophenol, respectively, in a time period of 60 min. The sonophotocatalytic activity process enhanced degradation efficiency to 99% in 60 min against Rhodamine B and 80% in 60 min against 4-chlorophenol.

This paper covers an analytical approach for predicting the bend angle of a laser formed sheet with a single laser scan. The proposed approach is based on the strain energy stored under the laser-irradiated area that causes plastic deformation of sheet due to laser heating. With any particular intensity of laser, the temperature profile established across the sheet thickness is determined by employing a one-dimensional transient heat conduction equation and by considering the loss of heat to the surrounding material by thermal conduction. Based on the temperature gradient across the sheet thickness, thermal strain, strain-induced stress, and bending moment are evaluated. By equating the strain energy stored in the sheet material due to thermal stress and strain with the strain energy stored due to the bending moment, the angle of bend in the sheet is determined. The results obtained with the proposed model are validated with the experiments performed on AISI 304 stainless steel and AA 1100 aluminum alloy sheet material of different thickness using CO2 laser with varying power and scanning speed. A three-dimensional finite element model is developed to validate the temperature profile predicted by the proposed model. The effectiveness of the proposed approach is validated by comparing the predicted bend angle with those predicted by other analytical models. Apart from this, the effect of various process parameters on the laser formed sheet was studied using microstructure and microhardness analysis. Finally, with the application of the proposed model, a process map is generated to achieve pure bending during laser forming.

Tissue engineering is emerging as a modern medicine fascination towards the establishment of human tissue banks; yet, these approaches typically involve cultures of only one type of cell and, therefore, do not recapitulate the native tissue physiology in toto. Co-culture models, comprised of different cell types, can potentially create the next level of complexity. However, conventional approaches involving multiple cell types and cell culture inserts do have limitations. To this end, here we demonstrate a novel cell culture insert that allows the use of any custom-made scaffold, free-flow of fluids/gases, dual cell seeding on either sides of the insert, easy stacking of multiple inserts and resizing it to any multi-well plate format as well as culture dishes. To prove the concept, electrospun silk fibroin scaffold was clipped onto the insert and was used for co-culturing of keratinocytes and fibroblast cells. The results indicated a successful fabrication of spatially organized skin tissue constructs having epidermal and dermal equivalent histology. Cell-laden inserts were stacked and used for simulated transportation studies. However, the conditions need further fine-tuning. All together, the results indicated that the novel cell culture insert with silk fibroin scaffold could be used as a facile, versatile and scalable approach to fabricate and transport 3D co-cultured tissue constructs in vitro, including but not limited to skin. The resultant tissue constructs can be explored for therapeutic applications, for instance as artificial skin substitute in wound healing, and for toxicological applications, for instance as reconstructed skin tissue model in skin irritation testing.

Gas turbines and aircraft engines are dominated by cyclic operating modes with fatigue-related loads. This may result in the acceleration of damage development on the components. Critical components of turbine blades and discs are exposed to cyclic thermal and mechanical multi-axial fatigue. In the current work, planar-biaxial Low-Cycle-Fatigue (LCF) tests are conducted using cruciform specimens at different test temperatures. The influence on the deformation and lifetime behaviour of the nickel-base disk alloy Inconel 718 is investigated at selected cyclic proportional loading cases, namely shear and equi-biaxial. The calculation of the stress and strain distribution of the cruciform specimens from the experimental data is difficult to obtain due to complex geometry and temperature gradients. Therefore, there is a need for Finite Element (FE) Simulations. A viscoplastic material model is considered to simulate the material behaviour subjected to uniaxial and the selected planar-biaxial loading conditions. At first, uniaxial simulation results are compared with the uniaxial experiment results for both batches of IN718. Then, the same material parameters are used for simulating the biaxial loading cases. The prediction of FE simulation results is in good agreement with the experimental LCF test for both shear and equi-biaxial loadings. The equivalent stress amplitude results of the biaxial simulation are compared with the uniaxial results. Furthermore, the lifetime is calculated based on the stabilized cycle from the simulation and by using Crossland and Sines multi-axial stress-based approaches. The Crossland model predicts fatigue life significantly better than the Sines model. Finally, the simulated lifetime results are compared with the experimental lifetime.

This study aims to develop Load and Resistance Factor Design (LRFD) provisions for movable bridges’ mechanical components. It requires the formulation of the limit state functions, determi...

The persistent efforts among the researchers are being done to reduce emissions by the exploration of different alternative fuels. The application of alternative fuel is also found to influence engine vibration. The present study explores the potential connection between the change of the engine operating parameters and the engine vibration pattern. The objective is to analyze the effect of alternative fuel on engine vibration and performance. The experiments are performed on two different engines of single cylinder (SC) and twin-cylinder (TC) variants at the load range of 0–34 Nm, with steps of 6.8 Nm and at the constant speed of 1500 rpm. The single cylinder engine, fueled with only diesel mode, is tested at two compression ratios (CRs) of 16.5 and 17.5. However, the twin-cylinder engine with a constant compression ratio of 16.5 is tested at both diesel unifuel and diesel-compressed natural gas (CNG) dual-fuel modes. Further, in dual-fuel mode, tests are conducted with compressed natural gas substitutions of 40%, 60%, and 80% for given loads and speed. The engine vibration signatures are measured in terms of root mean square (RMS) acceleration, representing the amplitude of vibration. The combustion parameters considered are cylinder pressure, rate of pressure rise, heat release rate (HRR), and ignition delay. At higher loads, the vibration amplitude increases along with the cylinder pressure. The maximum peak cylinder pressure (PCP) of 95 bar is found in the case of the single cylinder engine at the highest load condition that also produced a peak vibration of 3219 m/s2.

This work deals with the impact of Ni doping on the structural, morphological, electrical and optical characteristics of SnO2 thin films, deposited on soda-lime glass microslides (75 mm × 25 mm × 1.2 mm) at 400 °C by facile spray pyrolysis technique. The structural analysis (XRD) confirms that the prepared Ni:SnO2 thin films belong to the tetragonal rutile structure. The preferred growth orientation along the (211) and (301) planes shifted to the (200) plane due to the Ni dopant concentration. Scanning electron microscopic analysis reveals that the grain size is effectively modified by various nickel concentration in the films. XPS measurement indicates the presence of Sn4+ and Ni2+ in 3.0 at.% Ni:SnO2 thin film. The electrical studies reveal that all the films show n-type conductivity. The lowest resistivity (2.4 × 10–3 Ω cm), high carrier concentration (1.267 × 1020 cm−3) and high mobility (120 cm2/V s) are obtained for undoped SnO2 thin films. A slight variation in the resistivity and carrier concentration is observed for Ni-doped SnO2 films. The optical transmittance of 2.0 at.% Ni:SnO2 film shows maximum transmittance than undoped SnO2 film. The photoluminescence spectrum of undoped SnO2 and Ni:SnO2 thin films, excited at the wavelength of 325 nm, consists of the strong near band emission at 398 nm. The obtained result shows that 2.0 at.% Ni:SnO2 film has high optical and electrical conductivity; this could be useful in optoelectronic and gas sensing applications.

The hybrid composites was prepared from epoxy polymer layers with aluminum sheets of 1 and 2 layers. The epoxy polymer was mixed with conch sea shells (sharp parts) in order to gain more impact strength and incorporated with chopped banana fibers. The mechanical properties such as flexural, tensile, hardness tests were carried out along with the ballistic test. The microstructure SEM images showed bonding of banana fiber along with the banana fibers. Ballistic test with the short hand gun, and the conclusion made the composite fits for ballistic protection.

The growing demand for ultrafine surface generation has forced the researchers to look for new methods of polishing that can guarantee both qualities as well as productivity. The existing polishing methods have several limitations such as bluntness of tool due to loading, metallurgical changes on the polished surface due to frictional heat generated at the interface, etc. These limitations have prompted the researchers to develop self-sharpening polishing tools. One such method is Ice Bonded Abrasive Polishing (IBAP) which uses frozen slurry for polishing, where ice serves as a matrix to hold the abrasives. Frictional heat produced at tool work interface causes the tool to melt and thus exposes fresh abrasives present in different layers. This paper attempts to interpret the mechanisms responsible for the ultrafine surface generation and then to develop an analytical model for estimating material removal. During polishing, the asperities on work surface experience variable force due to the changing condition of the tool with time. Initially, the first layer of rigid ice with fixed abrasives interacts with the work surface, making it as a solid-solid interaction. Molten state of ice behaves as semisolid and leads to slurry formation afterward. Therefore, the work surface will experience two-body and three-body interactions simultaneously. The proposed model implements the concepts of contact mechanics for predicting material removal from the work surface and finally, the effectiveness of the model has been validated with experimental results.