Polymer-based composites have been drawing the attention of the research community for many decades, not only in academia but also in industry. However, continuously increasing environmental concerns have led the researchers to focus on natural composite materials. This is a challenge for researchers to develop a natural composite without compromising the composites’ excellent mechanical properties and tribological performance. In this research, coir and sugarcane are selected as the natural fillers, and epoxy resin has been chosen for matrix material. To look into the crystallinity of composites, XRD analysis was done. In addition, a mechanical study was done to look at the manufactured composites’ tensile and flexural characteristics. The tribological performance (i.e., wear rate and friction coefficient) of the composite samples is investigated by using a pin-on-disc setup. The parameters such as filler loading and normal load affecting the tribological performance of epoxy-based natural composites are studied. The results show that the wear and friction characteristics of the composite reinforced with sugarcane and coir were 10.78% and 57.80% lower than those of the neat composite, respectively.

@en

Computational analysis on film cooling effectiveness over a flat plate using different coolant injection hole geometries are reported. The designed computational setup and flow physics are suitably validated against the existing experimental results for an injection angle of 30°. The present study reports and compares the degree of film cooling effectiveness obtained by the different orientations of the coolant injection holes and their geometry, hole arrangements in the rows and number of rows. The computational domain was designed using Ansys Fluent. The blowing ratio is systematically ranged between 0.67 and 1.67. The performance of a given film cooling scheme is reported in terms of centreline (ηcl) and spatially averaged (η_sa) adiabatic effectiveness. It is observed that for single hole configuration, the semi-elliptic geometry increases the ηcl by ~66.67% up to x/D(ratio of downstream distance from hole to diameter of hole) = 50 at lower blowing ratios (0.67 and 1.00) and by ~50% up to x/D=100 at higher blowing ratios (1.33 and 1.67). For ηsa, an increment of ~200% and ~60% is achieved for all blowing ratios using the triangular and semi-elliptic geometries, respectively. For the multiple row arrangements, the two staggered rows delivered an increment in ηcl of ~77% up to x/D=50 and ~54% up to x/D=100. The two staggered configurations at 0° gave the highest effectiveness increment of ~177% up to x/D=50 while it was ~100% for up to x/D=100. Results indicate that the triangular geometry shows the highest values of the film cooling effectiveness, and a semi- elliptic geometry utilizes ~50% of the coolant mass flow than other coolant injection hole geometries while delivering higher effectiveness values.

@en

Every year at the onset of winter season (October–November), crop residue/parali/stubble burning starts in Punjab and Haryana, leading to heavy air pollution in Delhi, and adversely affecting human and environmental health. During this time, the combination of unfavourable meteorological conditions, additional emissions from stubble burning, and firework activities in this area causes the air quality to further deteriorate. In this study, we have attempted to understand the influence of parali and firecracker incidents on air pollutants’ variability over Delhi during the last three years (2020 to 2022). For this purpose, daily average particulate matter and gaseous pollutants data were fetched from the Central Pollution Control Board (CPCB), and daily total fire counts and fire radiative power (FRP) data were retrieved from NASA’s Fire Information for Resource Management System (FIRMS). A bigger area of severe burning is suggested by higher FRP values and higher fire counts in the middle of November in all the years considered. Three years satellite-based FIRMS data over Punjab and Haryana show the highest number of active fire counts in 2021 (n = 80,505) followed by 2020 (n = 75,428), and 2022 (n = 49,194). More than 90% parali burning incidents were observed in Punjab state only despite the considerable variability in numbers among the years. The significant effect of parali burning was seen on pollutant concentration variability. As the number of fire count increases or decreases in Punjab and Haryana, there is a corresponding increase or decrease in the particulate matter concentration with a time lag of few days (1 to 2 days). The trend in backward air mass trajectories suggests that the variable response time of pollutants’ concentration is due to local and distant sources with different air mass speeds. Our estimates suggest that stubble burning contributes 50–75% increment in PM_2.5 and 40 to 45% increase in PM₁₀ concentration between October and November. A good positive correlation between PM_2.5, PM₁₀, NO_X, and CO and fire counts (up to 0.8) suggests a strong influence of stubble burning on air quality over Delhi. Furthermore, the firecracker activities significantly increase the concentration of particulate matter with ~100% increment in PM_2.5 and ~55% increment in PM₁₀ mass concentrations for a relatively shorter period (1 to 2 days).

@en

In this study, the relationships between meteorological parameters (relative humidity, wind speed, temperature, planetary boundary layer, and rainfall) and air pollutants (particulate matter and gaseous pollutants) have been evaluated during a 3-year period from 2019 to 2021. Diffusion and dispersion of air contaminants were significantly influenced by meteorology over the capital city. The results of correlation matrix and principal component analysis (PCA) suggest a season’s specific influence of meteorological parameters on atmospheric pollutants’ concentration. Temperature has the strongest negative impact on pollutants’ concentration, and all the other studied meteorological parameters negatively (reduced) as well as positively (increased) impacted the air pollutants’ concentration. A two-way process was involved during the interaction of pollutants with relative humidity and wind speed. Due to enhanced moisture-holding capacity during non-monsoon summers, particles get larger and settle down on the ground via dry deposition processes. Winter’s decreased moisture-holding capacity causes water vapour coupled with air contaminants to remain suspended and further deteriorate the quality of the air. High wind speed helps in the dispersion and dilution but a high wind speed associated with dust particles may increase the pollutants’ level downwind side. The PM_2.5/PM₁₀ variation revealed that the accumulation effect of relative humidity on PM_2.5 was more intense than PM₁₀. Daily average location-specific rainfall data revealed that moderate to high rainfall has a potential wet scavenging impact on both particulate matters and gaseous pollutants.

@en

The impact of air pollution on people and the environment is a severe issue that has recently been the subject of extensive research. This study has looked at the factors that contribute to the seasonal and spatial variability of pollutant concentration over Delhi NCR from 2019 to 2021. Additionally, the causes of changes in air quality during the COVID-19’s lockdown period in 2020 have been discussed, along with comparisons to the pre-lockdown year (2019) and the post-lockdown year (2021). Seven pollutant parameters, viz., (PM2.5, PM10, NOx, CO, SO2, NH3, and O3) were retrieved from the air quality monitoring stations spread over Delhi NCR. The results show a significant temporal (seasonal) and spatial variability in the air pollutants’ concentration. The highest pollutant level was observed in winter and the lowest in summer seasons. The results suggest that the concentration of atmospheric pollutants was already lower (20–30%) before the implementation of the lockdown. Meteorology played an important role in emission reduction during the lockdown, in particular, and seasonal, in general. The results also suggest that Bhiwadi is not the most polluted city, as claimed in the World Air Quality Report 2022. The most polluted sites in terms of pollutant concentration were observed over Delhi in all the years considered. @en

The vibration and damping characteristics of the laminated composite cylindrical sandwich shell with carbon nanotube reinforced magnetorheological elastomer (CNT-MRE) core is presented in this article. Higher order shear deformation theory (HSDT) based on finite element (FE) formulation is employed to derive the governing equations of motion of the laminated composite cylindrical CNT-MRE sandwich shell. The present HSDT model of the cylindrical CNT-MRE sandwich shell is validated with the ABAQUS model in terms of natural frequencies on cantilever boundary condition. The influence of CNT reinforcement in the MRE layer of the cylindrical sandwich shell is also studied through the structural rigidity. The detailed parametric investigations are performed to study the influence of magnetic field intensities, thickness ratio, radius of curvature and ply orientation on the stiffness and damping behavior of composite cylindrical CNT-MRE sandwich shell.

@en

The present article investigates the dynamic characteristics of jute fiber-reinforced sandwich composite panels with periodic cores. The sandwich panel contains the jute fibers-reinforced polymer (JFRP) composites as face layers and the silicone rubber as the core layer. The tensile and flexural properties of JFRP composite material were examined using ASTM D3039 and ASTM D7264 standards. The finite element model was developed to obtain the dynamic properties of the composite sandwich panel with conventional and periodic cores. Furthermore, the influence of end condition, core to face layer thickness ratio, and face layer to core thickness ratio on the dynamic properties of the sandwich panels are presented. The numerical results indicate that the periodic core composite sandwich panel greatly influences the structural stiffness compared with a conventional composite sandwich panel.

@en

These day, due to tremendous growth of wireless communication and the need for higher data transfer rates and portable and compact devices, the need for antenna with a simple design, small size, reliable radiation pattern while retaining an incredibly large frequency spectrum is on high demand. However, Ultra-Wide Band (UWB) antenna design is particularly challenging for portable devices. Nevertheless, UWB antenna design faces several challenges especially for portable devices, containing the UWB quality of impedance matching, small antenna size, constant group delay, radiation stability, and low production costs, etc., for consumer usage. Because of their low profile, broad impedance bandwidth and compact design, ease of fabrication, etc. Today, Ultra-Wide-Band antennas (UWB) have been analyzed and their features explored in the future wireless communication of the fifth generation (5G). The antennas are called planned and the scale should be minimal, so that the geometry in the 5G candidate frequency bands will be properly optimized to operate within an ultra-wide frequency band. Microstrip antenna are very successful candidates for wireless communication systems. In this research paper, by using UWB Application, we proposed a novel concept design and study of a coplanar wave guide (CPW) fed UWB for 5G. Our proposed patch antenna is elliptical in shape that offers greater degree of freedom and flexibility in design compared to circular configuration and can also provide circular polarization by proper selection of ellipse feed line while CPW-fed provides strong matching impedance.

@en

This paper presents the dynamic responses of sandwich beams with 3D printed thermoplastic composite face sheets and multi-walled carbon nanotubes reinforced magnetorheological elastomer (MWCNT-MR elastomer) cores under non-uniform magnetic fields. A higher-order beam theory (HoBT) is employed to express the beam‘s displacement field. The governing equations of the 3D printed thermoplastic sandwich beam are derived using Lagrange‘s principle and discretized by the finite element method. The validity of the present method is confirmed through comparison with the results available in the literature. The stiffness and damping characteristics of the 3D printed thermoplastic sandwich beam are investigated in relation to support conditions, non-homogeneous magnetic flux, and core-face sheet thickness ratio.

@en

The presence of a wide range of high- and low-resolution devices renders the images to experience changes in respect to aspect ratio and size for better adaptability. This paper proposes a novel and effective technique that vanquishes the problems encountered in the conventional seam carving method. To achieve minimum distortion in salient objects of the image, the proposed technique restricts intersection or overlapping of multiple seams in the horizontal and vertical direction and bypasses them to the neighboring low energy pixel. The proposed technique hinders the pixel selection from a single row or column beyond the defined threshold so as to save the image information and reduce distortion at a single location. To justify the effectiveness of the proposed technique, results have been presented in comparison with the five state-of-the-art image retargeting techniques. Compared with the conventional techniques, this technique shows remarkable results in terms of low distortion percentage. The proposed technique also produces excellent results for shrinkage and enlargement of a single image multiple times.

@en

Modifications achieved in the ignition delay time of shellac-based pyrotechnic igniter using different additives of varying particle size are observed and compared. 40 different pyrotechnic compositions were prepared using five additives i.e. aluminium, magnesium, red iron oxide, naphthalene and activated carbon. Four particle sizes i.e. <75 μm, 75–150 μm, 150–300 μm, 300–600 μm and two weight percentages of the additives i.e. 3% and 5% were investigated. A base composition, without any additive, was also prepared to compare and investigate the effects of additives and their particle size on the ignition delay time of the composition. The incorporation of additives significantly reduced the ignition delay time of the base composition. Addition of 5% red iron oxide having a particle size of <75 µm, delivered the maximum decrement in ignition delay time i.e. by 49.7%. Naphthalene of particle size of <75 µm added as 3% in the composition weight, provided the minimum reduction in the ignition delay time i.e. by 13.7%. It was also observed that all of the additives exhibited a similar manner of decrement in ignition delay time as the particle size decreased, except for naphthalene which exhibited an opposite trend.

@en

Flow visualization is the direct observation of fluid flow. Moving fluids form complex patterns and understanding and visualizing those patterns is an important aspect in aerospace industry. The previously existing research and results were taken into consideration for design parameters and calculation for dimensions of various parts of the wind tunnel. Design calculations allow wind velocities in the range of 1-3 m/s at the test section. The design includes a rectangular test section of 0.06m x 0.30m cross-section for accommodation of test object of width 0.06m. The design was made in SolidWorks and was fabricated with basic materials like plywood and acrylic sheets. PC cabinet fans were used for flow circulation. Liquid wax is utilized for the purpose of smoke generation and rubber and PVC pipes were utilized for smoke containment and delivery system. Profiles that were used for testing included cylinder, sphere, cuboid, NACA airfoils and flat plate.

@en