This study presents the longest time series of aerosol optical properties and Precipitable Water Vapor (PW) from two AERONET sites in the Indo-Gangetic Plains (IGP). Analyzing 22 years of data (2001–2022) from Kanpur and 16 years (2007–2023) from Gandhi College, the study focuses on Aerosol Optical Depth (AOD), Ångström Exponent (α), Single Scattering Albedo (SSA), and Precipitable Water Vapor (PW). Significant variability in aerosol properties is observed across monthly, seasonal, and annual scales. The highest mean AOD500 values, coupled with higher α440–870 during post-monsoon and winter, indicate the dominance of fine-mode aerosols. A decrease in SSA with wavelength during these seasons further highlights the absorbing nature of these fine-mode aerosols, driven by fossil fuels and biomass burning. In contrast, summer and pre-monsoon have relatively lower mean AOD500, lowest α440–870, and increased SSA with wavelength, suggesting the dominance of coarse-mode scattering dust aerosols. PW exhibits a seasonal cycle, reaching its peak during the monsoon due to moisture transport from the Arabian Sea and Bay of Bengal, then decreasing post-monsoon as drier conditions prevail. Long-term annual trends reveal increasing aerosol concentrations, with AOD500 rising by 18% at Kanpur and 29% at Gandhi College, suggesting faster aerosol loading at the latter. Sub-period analysis indicates a slowdown in AOD500 increase during 2012–2023 at Kanpur, indicating potential stabilization post-industrialization, while Gandhi College’s more pronounced AOD500 and α440–870 increase underscores the growing impact of fine aerosols in rural IGP areas. Kanpur shows a sustained SSA increase, though at a slower rate in recent years, indicating dominant scattering aerosols. In contrast, Gandhi College has transitioned from moderate SSA increases to declines at longer wavelengths, suggesting enhanced fine-mode absorbing aerosols. At Gandhi College, the decline in PW reduces atmospheric moisture, limiting wet scavenging and likely contributing to the rise in fine-mode aerosols, especially during the monsoon and post-monsoon seasons. Our findings highlight the evolving aerosol sources in the IGP, with Kanpur stabilizing and rural areas like Gandhi College seeing continued increases in pollution.

This study presents a comprehensive finite element investigation into the design optimization of an ultra-high temperature ceramic matrix composite thruster for green bipropellant systems. Focusing on ZrB2–SiC–Cfiber composites, it explores their thermal and mechanical response under realistic transient combustion conditions. Two geometries, a simplified and a complex full-featured model, were evaluated to assess the impact of geometric fidelity on stress prediction. The complex thruster model (CTM) offered improved resolution of temperature gradients and stress concentrations, especially near flange and convergent regions, and was adopted for optimization. A parametric study with nine wall thickness profiles identified a 2 mm tapered configuration in both convergent and divergent sections that minimized mass while maintaining structural integrity. This optimized profile reduced peak thermal stress and overall mass without compromising safety margins. Transient thermal and strain analyses showed that thermal stress dominates initially (≤3 s), while thermal strain becomes critical later due to stiffness degradation. Damage risk was evaluated using temperature-dependent stress margins at four critical locations. Time-dependent failure maps revealed throat degradation for short burns and flange cracking for longer durations. All analyses were conducted under hot-fire conditions without cooling. The validated methodology supports durable, lightweight nozzle designs for future green propulsion missions.

Solid composite propellants continue to play a key role in space and defense propulsion due to their high energy density, ease of handling, and manufacturing scalability. While several studies have investigated the effect of individual additives on propellant performance, most are limited to a fixed weight percentage or particle size, making it difficult to derive comprehensive design guidelines. This study presents a systematic comparative investigation into the influence of various additives (Al, Fe₂O₃, CuCr₂O₄, and thermite combinations) and their particle sizes/loadings on the performance of polyvinyl chloride (PVC)/ammonium perchlorate (AP)-based composite propellants. Over 30 distinct formulations were experimentally characterized for burn rate, density, adiabatic flame temperature (AFT), and mass flow rate to establish comprehensive performance trends and trade-offs. The results demonstrate that smaller metal particle sizes and higher additive loadings generally enhance burn rate and mass flow, indicative of catalytic effects. Thermochemical analysis supports the significant exothermic contribution of the Al–Fe₂O₃ thermite reaction (–851.5 kJ/mol) to increased combustion energy. Furthermore, calculated oxidizer-balance percentages correlate with AFT and burn rate, with near-stoichiometric formulations exhibiting peak performance. The highest theoretical thrust (∼73 N) was predicted for a Fe₂O₃-rich formulation aligning with high energy and burn rate. While the catalytic mechanisms of these additives are known, the key contribution of this work lies in the extensive, comparative dataset across a wide range of propellant compositions. This broad dataset serves as a valuable resource for optimizing propellant formulations, validating combustion models, and guiding future propellant design.

This study presents a simulation-based damage modeling and fatigue risk assessment of a reusable ceramic matrix composite thruster designed for short-duration, green bipropellant propulsion systems. The thruster is constructed from a fiber-reinforced ultra-high temperature ceramic matrix composite composed of zirconium diboride, silicon carbide, and carbon fibers. Time-resolved thermal and structural simulations are conducted on a validated thruster geometry to characterize the severity of early-stage thermal shock, stress buildup, and potential degradation pathways. Unlike traditional fatigue studies that rely on empirical fatigue constants or Paris-law-based crack-growth models, this work introduces a simulation-derived stress-margin envelope methodology that incorporates ±20% variability in temperature-dependent material strength, offering a physically grounded yet conservative risk estimate. From this, a normalized risk index is derived to evaluate the likelihood of damage initiation in critical regions over the 0–10 s firing window. The results indicate that the convergent throat region experiences a peak thermal gradient rate of approximately 380 K/s, with the normalized thermal shock index exceeding 43. Stress margins in this region collapse by 2.3 s, while margin loss in the flange curvature appears near 8 s. These findings are mapped into green, yellow, and red risk bands to classify operational safety zones. All the results assume no active cooling, representing conservative operating limits. If regenerative or ablative cooling is implemented, these margins would improve significantly. The framework established here enables a transparent, reproducible methodology for evaluating lifetime safety in ceramic propulsion nozzles and serves as a foundational tool for fatigue-resilient component design in green space engines.

Hydrazinium nitroformate (HNF) is a chlorine-free, high-energy oxidizer with promising applications in green propulsion systems. This review examines the thermal decomposition, combustion kinetics, flame structure, and behavior of HNF, while critically evaluating the current body of literature. Thermal studies reveal that HNF undergoes two-stage decomposition, with exothermic peaks at 136°C and 138°C and an activation energy of 150 kJ/mol, determined using Kissinger and Ozawa methods. The decomposition products include nitroform, hydrazine, and nitrogen oxides, with a 72.5% weight loss in the first stage (105°C–142°C) and 24.5% in the second stage (142°C–210°C). Combustion studies identify a three-zone flame structure: fizz zone, dark zone, and luminous flame zone, with temperatures ranging from 1320 to 1540 K near the surface to 2720 K in the outer flame. HNF exhibits a high-pressure exponent (∼0.85), necessitating optimization through burn rate modifiers (BRMs) and advanced formulations. While HNF demonstrates superior specific impulse and reduced exhaust plume radiation compared to ammonium perchlorate (AP), its needle-like crystal morphology poses challenges for handling and propellant integration. This review emphasizes the need for advanced diagnostic techniques, computational modeling, and innovative BRMs, along with polymeric binders that are compatible with HNF and can improve the performance of HNF-based systems, offering valuable insights for green propellant development.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.