National Institute of Technology Karnataka

Message Queuing Telemetry Transport (MQTT) has emerged as the widely adopted application layer protocol for IoT environments because of its lightweight header, minimal power, and bandwidth requirements. Despite its popularity, the earlier version of the protocol, MQTT v3.1.1, encounters performance issues in large-scale implementations and required an update to handle the growing requirements of modern IoT applications. In response to these concerns, MQTT v5.0 was released with several significant features designed to enhance the reliability, user experience, and performance of IoT systems. While the MQTT protocol features were intended to facilitate robust and efficient communications, adversaries could exploit these features to mount various types of attacks in IoT deployments. More specifically, the Denial of Service (DoS) attacks towards the MQTT protocol have recently gained a lot of attention from the research community. However, the existing works primarily focus only on exploring the possibilities of misusing the MQTT v3.1.1 protocol features to generate DoS attacks in IoT realms. In this work, we attempt to extensively investigate the advanced protocol features of MQTT v5.0 that can be exploited to launch DDoS attacks impacting the IoT paradigm. We present the first critical evaluation of Distributed Denial of Service (DDoS) attacks on the MQTT v5.0 protocol by analyzing three significant features: CONNECT Properties, User Properties, and Flow Control. Moreover, we systematically propose attack scenarios based on the adversary’s capabilities, thus illustrating the practicality of proposed attacks in real-world scenarios. Furthermore, we built a real-world testbed for IoT healthcare application to evaluate the severity of the identified attacks. The experimental results demonstrate the effectiveness of these attacks in impacting the availability of guaranteed IoT services to legitimate users, even in times of need. Additionally, we disclose the insightful findings of this work as takeaways and present research initiatives toward developing effective defense mechanisms for MQTT v5.0 protocol. We hope that such a discussion could pave the way for future research, contributing to MQTT v5.0 security and resiliency.

Bio-based polymers have gained huge attention in the recent past for their application in various domains, especially food packaging. The petroleum-based polymers have a significant negative impact on the ecosystem owing to their non-biodegradability. Therefore, a sustainable yet efficient alternative is required which is both safe and non-toxic. Food packaging technologies with the latest innovations are promoting active and smart packaging applications which promise quick, safe and efficient ways to monitor the quality of stored foods. These materials are being explored in applications such as antimicrobial wraps, moisture barrier coatings, biodegradable trays, and oxygen-scavenging films. Nanotechnology has emerged as a superior alternative as it can enhance food protection while reducing the raw material requirement and waste generation. The present review focuses on the recent developments in active and smart food packaging with special emphasis on bio-based polymer nanocomposites. The various polymer nanocomposites, their properties and safety concerns with respect to food packaging are summarized in this review article besides providing prospects for the current research area.

The influence of CO2 gas concentration on the co-electrolysis performance of an electrolyte-supported button cell (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) was investigated. At 800 oC/1.5V, the interfacial polarization resistance (Rp) values for 10%CO2/15%H2O and 30%CO2/15%H2O are 7.19 and 26.91 Ω.cm², respectively. CO2 gas concentration significantly affects the Rp value. Gas diffusion resistance is dominant in the overall polarization resistance. As the CO2 concentration increases (10%→30%), H2 consumption increases, indicating RWGS dominance. For 30% CO2/15% H2O, CO2 out is slightly more than the input value due to the WGS and Boudouard reactions. As the applied voltage value increases from OCV, the H2 residue increases. H2O and CO2 co-electrolysis occurs at 1.5 V. The post-test XRD and Raman spectra results show NiO reduction and metallic Ni appearance. The post-test FE-SEM micrographs show no delamination at the air electrode/electrolyte interface, and carbon deposition is observed in the composite fuel electrode layer. Graphical abstract

Reconfigurable Intelligent Surface (RIS) technology has emerged as a promising solution to address the limitations of Line-of-Sight (LOS) communication in Radio over Free Space Optics (RoFSO) systems, particularly in the context of 5 G and beyond-5 G vehicular connectivity in smart cities. One of the primary challenges in RoFSO systems is the occurrence of skip zones, which disrupt communication links. RIS technology offers a novel approach to establishing connectivity in both LOS and non-line-of-sight (NLOS) scenarios, effectively mitigating signal blockage issues. This research paper proposes a multi-RIS-assisted RoFSO system that employs the Malaga distribution to model atmospheric turbulence for NLOS communication scenarios involving multiple RIS units. The study derives exact closed-form expressions for key performance metrics, including the outage probability, ergodic channel capacity, and average bit error rate. The analysis incorporates heterodyne detection and evaluates two modulation schemes: differential binary phase shift keying (DBPSK) and M-ary quadrature amplitude modulation (M-QAM). A comprehensive comparison of results is conducted under varying turbulence conditions, link lengths, and scattering errors. The findings demonstrate that while multi-RIS systems often underperform compared to single-RIS systems, they play a critical role in maintaining RoFSO communication links when single-RIS systems fail. This capability is particularly advantageous in Vehicle-to-Infrastructure (V2I) communication scenarios. The insights from this study contribute to the advancement and optimization of RoFSO technology, offering a pathway to enhanced connectivity and improved performance in smart city environments.

The Event Horizon Telescope (EHT) Collaboration recently published the first images of the supermassive black holes in the cores of the Messier 87 and Milky Way galaxies. These observations have provided a new means to study supermassive black holes and probe physical processes occurring in the strong-field regime. We review the prospects of future observations and theoretical studies of supermassive black hole systems. Current ground-based very-long-baseline interferometry (VLBI) arrays like the EHT and proposed future extensions like the next-generation Event Horizon Telescope will greatly enhance the capabilities of black-hole imaging interferometry. These enhancements will open up several previously inaccessible avenues of investigation, thereby providing important new insights into the properties of supermassive black holes and their environments. This review describes the current state of knowledge for five key science cases, summarising the unique challenges and opportunities for fundamental physics investigations that future mm/sub-mm VLBI developments will enable.

The wear performance of partially oxidized NiCr and NiCrBSiFe coatings were investigated by varing load and speed. The partial oxidized powders were processed from the alloy powder using a flame spray process that involved spraying into distilled water. The partially oxidized powder was then plasma-sprayed onto MDN321 steel. The coatings were characterized for adhesive strength, microhardness, and density. The wear behavior was evaluated at disc speeds of 1, 2, and 3 m/s, with loads ranging from 10 to 50 N, over a 3000 m sliding distance. A significant difference in wear rates between the coating and substrate was observed. Operating at a sliding velocity of 1 m/s under a 10 N load, the substrate’s wear rate was found to be 3.56 times higher than that of the NiCrBSiFe coating, whereas for NiCr coating, it was 2.78 times higher. Wear rate coefficient performance shift takes place between the coatings at 12 N-m/s, product of applied load (C) and sliding velocity (V). In NiCrBSiFe coating, the wear mechanism observed at lower speeds and loads is micro-brittle and mechanism shifts to abrasive wear at higher speeds and loads. In the NiCr partially oxidized coating, the wear mechanism observed involves spallation of the coating at higher loads and adhesive wear at lower loads. Thermo gravimetric analysis of the coatings revealed a weight loss percentage of 1.42 for NiCrBSiFe and 14.09 for NiCr coatings. These findings highlight the NiCrBSiFe partially oxidized coating as being tenfold more stable at high temperatures compared to the NiCr partially oxidized coating.

The past decade has witnessed profound transformations in the financial sector, driven by the integration of cutting-edge technologies into its core operations. Consequently, banks are increasingly utilizing technologies such as artificial intelligence (AI), blockchain, and big data analytics to offer personalized services, streamline transactions, and improve risk management, enabling the development of new financial products and services that cater to the diverse and evolving needs of customers. Despite these benefits, the banking landscape has also brought about complex challenges, particularly in the fight against money laundering. Money laundering remains a significant threat to the integrity of financial systems, as criminals exploit digital advancements to conceal illicit activities. The growing complexity of digital transactions and the increasing volume of financial data have made detecting and preventing money laundering more challenging than ever. Existing AI-based solutions, while effective to some extent, often grapple with class imbalance issues. This paper addresses the challenge by introducing a novel model named GAGAN (Graph Attention Generative Adversarial Network) and enhances the detection of money laundering activities in bank transactions. The proposed model further addresses the issue of class imbalance, by incorporating Conditional Generative Adversarial Network (cGAN) and Graph Attention Networks (GAT). The GAT classifier is then employed to accurately classify transactions, leveraging attention mechanisms to focus on the most relevant parts of the graph. Empirical results reveal that the proposed model achieves impressive performance metrics, with an accuracy of 98.62%, precision of 98.10%, recall of 98.92%, F1 score of 98.49%, AUC-ROC of 0.99, and a MCC score of 0.991. These results underscore the efficacy of the model in accurately identifying money laundering transactions, showcasing its potential as a robust tool for financial crime detection.

Coastal aquifers are vulnerable to contamination due to extensive beach sand mining and effluents from processing plants, leading to heavy metal dispersion in groundwater. This study integrates hydrodynamic and geochemical modelling to predict contaminant transport and evaluates the effectiveness of clay-amended laterite mixtures in immobilising heavy metals. A 3D transient state finite element model (FEFLOW) was developed to simulate the transport mechanisms of titanium (Ti), iron (Fe), and magnesium (Mg) in the Chavara coastal zone, considering advective–dispersive transport and geochemical interactions. Results indicate significant contaminant plume migration along primary flow paths influenced by macro-scale hydrodynamics (groundwater flow) and micro-scale adsorption kinetics of laterite. Forecasting highlighted significant southwest movement of contaminants with maximum velocities of 18.40 m/day. The 7-year hydraulic modelling scenario predicts dispersion over 6.2–7.1 km² area, emphasising groundwater vulnerability to pumping rates. Contaminant levels reached concentrations of Fe—180 ppm, Mg—48 ppm, and Ti—0.56 mg/L ppm. Simulation shows a 21.6% reduction in hydraulic head and a 71.34% decrease in storage capture with increased extraction, compared to a 0.61% head reduction from variations in specific storage. The study also explores heavy metal immobilization using laterite soil modified with bentonite, kaolinite, and zeolite clay through Langmuir and Freundlich adsorption models. Bentonite-amended laterites demonstrated the highest adsorption efficiency (Kd—54.8 L/kg for Ti, 22.1 L/kg for Fe, and 17.9 L/kg for Mg), attributed to its expansive interlayer structure and high cation exchange capacity. This research provides a multiscale interdisciplinary approach offering sustainable solutions for groundwater remediation in industrial coastal regions.

This study examines how well boundary layer suction can prevent a highly loadedaxial compressor cascade from cornering out in a droplet-laden flow. SteadyReynolds Averaged Numerical simulations are carried out to examine the impactof various suction slot configurations on the loss coefficient and flowmodifications. It is observed that, when the boundary layer suction is applied alonga portion of the blade span, it minimizes the flow separation locally at that region.Even though this is beneficial, providing a suction slot only a portion of the bladeenhances the flow disturbances. On the other hand, when the suction scheme isemployed on the entire blade span, it considerably increases flow uniformity. Inresponse to the high cross-passage pressure gradient causing persistent three-dimensional corner separation, a combined suction strategy was developed. Thismethod involved the use of a spanwise slot on the suction surface and another onthe endwall, modeled as Flow Extraction and Wall Suction (FEWS). The approachaimed to eliminate separated flow on the blade's suction surface, significantlymitigate 3D corner separation, and improve the uniformity of the flow field. It isobserved that, compared to a dry scenario, a wet environment with a suction flowrate of 1%, significantly lowered the total pressure loss coefficient by 26%.

The COVID-19 pandemic created an unprecedented disruption and has checked the robustness of the global supply chains. This article, for the first time, addresses a Dual Channel Supply Chain (DCSC) competition between an upstream manufacturer and downstream traditional retail stores (r-store) and electronic stores (e-store) under pandemic-induced demand disruptions. We employed the Stackelberg game to model the multi-agent interaction among the upstream manufacturer and downstream r-store and e-store. The competitive subgame between r-store and e-store was modelled using a horizontal Nash game, assuming their comparable channel power. To assess the impact of demand disruption, the benchmark pre-pandemic setting was compared against panic buying, lock-down, and post-lock-down situations in alignment with the actual occurrence of events. The optimal pricing strategies and consequent profit functions of all the channel members were derived by conducting an equilibrium analysis. Further, a computational analysis using Monte-Carlo simulation was conducted to obtain managerial insights. The study found that r-store profited the most during the panic buying period, except for high-cost products. On the other hand, the e-store benefited significantly during the post-lock-down period. The lock-down period was unfavorable for both r-store and e-store. Manufacturers achieved maximum profits during panic buying, especially for essential goods. Both lock-down and post-lock-down periods were less favourable for the upstream channel partner. Findings from the study will aid the management practitioners in developing policies to make the DCSC robust during pandemic disruptions.

In this work, a titanium-incorporated metal–organic framework nanoadditive was used to study its efficiency in removing heavy metals and dyes from contaminated water. The use of MIL-125 (Ti) nanoadditive-incorporated polysulfone membranes has been tested for the elimination of heavy metals such as cadmium and lead as well as synthetic dyes, such as reactive black-5 (RB-5) and reactive orange -16 (RO-16). The incorporation of metal–organic frameworks (MOFs) into polysulfone matrices can increase the performance of the membrane for specific applications, such as dye removal and heavy metal rejection. The MIL-125 (Ti) is a well-known MOF with excellent chemical stability, large surface area, and adjustable pore size, making it suitable for membrane fabrication. This study fabricated membranes composed of MIL-125(Ti) and polysulfone (PSF) with MOF doses ranging from 0.5 to 3 wt %. Compared with the pristine PSF membrane, the pore-forming agent PVP was used at a 12% concentration, increasing the pore size and porosity. The hydrophilicity, water flux, and antifouling nature of the fabricated membrane were studied. The dye removal and heavy metal rejection experiments were carried out, and a dye removal efficiency of 90% for RB-5 and 47% for RO-16 was exhibited by the M-1 membrane. Furthermore, the M-2 membrane resulted in heavy metal rejection of 89.33% for Cd2+, and M-3 resulted in 68.81% for Pb2+ at a feed concentration of 500 ppm. Hence, the membranes showed good stability and efficiency with a high feed concentration of heavy metals. In the present study, metal ion rejection was studied without the use of any complexing agents.

The uncompromising need to protect against harmful UVA and UVB radiation and to alleviate plastic pollution has catalyzed the development of innovative, eco-friendly materials. This study presents a solution by developing a transparent coating derived from Soy Protein Isolate (SPI), offering UV protection as well as sustainable bioplastic alternatives to synthetic polymers. The structural and chemical properties of SPI coatings, highlighting their UV protective capabilities, were analyzed using UV absorption spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR), and High-Resolution Liquid Chromatography-Mass Spectrometry (HR-LCMS). X-ray photoelectron spectroscopy (XPS) analysis showed decrease in carbon composition between SPI powder and film, suggesting a different surface composition for the film from powder, whereas denaturation was further confirmed by DSC. Contact angle measurement gives insights about the surface properties of the film and HR-LCMS gives the amino acids present in SPI. The biodegradability of SPI, coupled with its durability and transparency, underscores its potential as a versatile host material for various coatings. highlighting its additional advantage. From the FE-SEM study, the coating shows uniformity, which presents an innovative approach to transparent coatings. Notably, alongside transparency, the inherent UV absorption properties of SPI remained consistent before and after denaturation, showing potential applications in UV protective biodegradable coatings for various industrial applications, promoting eco-friendly alternatives to synthetic polymers.

Understanding cement at the atomic level is essential for optimizing its performance, durability, and sustainability. This review explores the atomic structure and defects of key cement phases—C-S-H, C₃S, C₂S, C₃A, and C₄AF—and their impact on hydration reactions and phase formation. Calcium silicate hydrate (C-S-H), the primary hydration product, is examined for its amorphous structure, which governs strength and durability. Structural defects, including vacancies and dislocations in cement phases, influence hydration kinetics and mechanical properties. Interactions at the atomic scale, such as hydration reactions driven by water molecules and the formation of C-S-H gel, are discussed alongside the role of temperature and pressure in accelerating or decelerating these processes. Insights into atomic arrangements, defects, and environmental conditions provide pathways to improve cement formulations, enhance durability, and reduce environmental impact. This comprehensive review deepens the understanding of cement's fundamental behaviour, enabling advancements in sustainable and high-performance cementitious materials.

We proposed an optoelectronic oscillator (OEO), incorporating a dual parallel Mach–Zehnder modulator (DP-MZM) and quadratic fiber Bragg grating (Q-FBG) for microwave photonic (MWP) applications. The suggested system combines the unique dispersive and reflective properties of the Q-FBG to achieve enhanced frequency stability and spectral purity. The Q-FBG facilitates precise control over the oscillation frequency by introducing quadratic phase modulation, effectively suppressing spurious modes and improving phase noise performance. Experimental results demonstrate the capability of the OEO-QFBG system to generate low-phase-noise microwave signals with superior stability compared to conventional OEO designs. A 20 GHz microwave signal with low phase noise of –134.93 dBc Hz⁻¹ at 10 kHz offset was generated. This work underscores the potential of integrating advanced photonic components, such as Q-FBGs, for advanced microwave photonics applications, including radar systems, communications, and high-precision instrumentation.

In this paper, we investigate the outage probability performance of underwater wireless optical communication for a vertical link. Due to temperature and salinity variations, turbulence in the vertical link ranges from strong to weak. The vertical link turbulence is modeled using a cascade of the gamma–gamma and hyperbolic tangent log-normal distributions. In addition to turbulence, we consider the impact of attenuation losses in the underwater medium and pointing errors at the receiver for outage probability analysis. A closed-form expression for the outage probability of the vertical link is derived. Outage probability results are presented for different water types, signal-to-noise ratio thresholds, degrees of pointing errors, and data rates. Additionally, an asymptotic analysis is provided to offer insights at high transmitted power. The accuracy of the derived closed-form expression is validated using Monte Carlo simulations.

The present study investigates the influence of multi-axial forging (MAF) on the microstructure, mechanical, and wear properties of the AA5083 alloy. After solution treatment, the alloy was subjected to three MAF cycles at room temperature with a strain of 0.63 per cycle. The evolution of the microstructure was analyzed using optical microscopy, field emission gun scanning electron microscopy, and x-ray diffraction. Mechanical properties were evaluated through tensile testing, and Vicker’s micro-hardness and wear behavior of the alloys were investigated using reciprocating wear tests. The results demonstrated significant improvement in properties after the third MAF cycle, forming 8.3 μm wide shear bands and a refined grain structure. The alloy achieved maximum hardness (130 HV), tensile strength (334 MPa), and elongation to failure (8.01%), along with a reduced strain-hardening exponent (0.27). Wear resistance showed marked enhancement, with wear volume reductions of 36%, 49%, and 21% under 1, 2, and 4 N loads, respectively. Similarly, wear rates decreased by 64%, 49%, and 15% under the same loads. These findings emphasize the MAF process's effectiveness in enhancing the mechanical and wear properties of AA5083 alloy, indicating its potential for advanced material processing techniques.

The development of innovative core structures and peripheral groups for organic hole‐transporting materials (HTMs) continues to be a focal point in enhancing the performance of perovskite solar cells (PVSCs). This study reports the design and synthesis of dopant‐free pyrazine‐based HTMs. PS1 features a D–A–D type structure with pyrazine as the acceptor and 4,4′‐dimethoxy triphenylamine (4,4′‐OMe‐TPA) as the donor, while PS2 adopts a D–π–A–π–D configuration with an additional thiophene unit as π‐spacer along with 4,4′‐OMe‐TPA as donor. Both compounds are synthesized through a simple two‐step synthetic procedure. These HTMs are subjected to structural, photophysical, electrochemical, theoretical, and photoelectrochemical studies with an emphasis on evaluation of structure–property relationships. Theoretical studies are conducted to explore the electronic distribution, optimized molecular structure, and frontier molecular orbitals. Their performance in PVSCs is systematically evaluated without adding dopants. PS2 exhibits superior photoluminescence quenching compared to PS1, indicating more efficient charge transfer from the perovskite layer. Notably, PS2 achieves a power conversion efficiency (PCE) of 11.9%, surpassing the performance of PS1 (PCE of 10.15%). These findings highlight the potential of adjusting the electron‐deficient core and π‐bridge units as an effective strategy to optimize the properties of HTMs and improve their performance in PVSC applications.

BackgroundDue to lower limb impairment, people use greater trunk flexion strategies and cannot maintain the alignment of the upper body, leading to loss of lordosis over time. ObjectiveA comprehensive study is needed to understand the heightened trunk flexion effect on lumbar and cervical lordosis and associated joint moments. MethodsThe three sit-to-stand-to-sit strategies, Natural, Full trunk flexion, and Pelvis-spine alignment, were conducted in 3D motion capture. The hypothesis is that increasing the total lumbar and cervical lordosis depth will reduce the total lumbosacral and cervicothoracic joint moment. Using Visual 3D, inverse kinematics and dynamics for joint moments and angles of the head, trunk, and pelvis at five events/phases, and the corresponding lordosis depth was calculated. ResultsPelvis-spine alignment strategies show a strong positive correlation (r = 0.70) between the total depth of lordosis and reducing the lumbosacral and cervicothoracic joint moment. The full flexion strategy mirrored the compensatory movement with a negative correlation (r = −0.88) on the reduction of lordosis depth and compensated by increasing the cervical lordosis depth. ConclusionsThese findings guide the correcting of spine disorders, the development of physical rehabilitation programs, the design of devices, and the correctness of posture to prevent low back pain and disease progression.