Publication

The study focuses on the polarization dynamics of the ferroelectric phase under an external magnetic field in a trilayered magnetoelectric (ME) composite of 0.94(Na0.5Bi0.5TiO3)-0.06BaTiO3 (NBT-BT)/CoFe2O4(CFO)/NBT-BT. With the estimation of gradient size of the strain across the interface, the thin films with varying top layer (NBT-BT) thicknesses were fabricated. The piezoelectric displacement curves revealed the linear characteristics for the 30 nm NBT-BT ME composite due to the presence of dominant interfacial strain. Time-resolved polarization switching studies confirmed the role of interfacial strain on the time scale of polarization switching of the ferroelectric phase. Magnetic field-assisted piezoresponse force microscopy studies confirmed the presence of nonlinear contribution like polarization rotation in the 100 nm NBT-BT ME composite. The interfacial strain was found to operate in a way that imposes constraints on the polarization rotation in a spatial region of ∼20-30 nm away from the interface. However, at a spatial region >30 nm, the interfacial strain was found to supplement the field-induced strain and assisted the polarization rotation to happen. The spatial-dependent behavioral analysis of the interface strain on the polarization dynamics will help in using the ME composite for targeted device applications such as actuators or energy harvesters.

Introduction and Background: Spiral bevel gears are ubiquitous in numerous power transmission systems. The exigent demands such as high performance, more strength and less noise in helicopter drives can be met by selecting the optimal geometrical design parameters. However, a comprehensive study on the influences of geometric parameters on the transmission system dynamics is not found in the literature. Objective: Therefore, in this study, the effects of geometric design parameters such as spiral angle, pressure angle and pitch cone angle on the spiral bevel gear set dynamic characteristics for various boundary conditions are studied. Method: Firstly, the analytical modelling of coupled lateral-axial–torsional vibrations of the spiral bevel gear set is derived theoretically under few assumptions. Then the emphasis on the effects of geometric parameters on the dynamic characteristics such as critical speeds, coupled mode shapes and unbalance vibration response of the gear pair supported by flexible and rigid boundary conditions are investigated numerically. Results: Under rigid support conditions, it is observed that there is no remarkable influence of geometric parameters on the critical speeds. However, the unbalance response amplitudes at and around the resonance peaks are notably affected. Whereas the critical speeds and unbalance responses are essentially affected by the variation of axial and torsional stiffness at the supports. Meanwhile, the influence of geometric parameters on the critical speeds corresponding to torsional and axial modes is remarkable for the flexible support conditions. Furthermore, the steady-state response due to combined torsional and unbalance excitations is also studied, and the results show that the geometric parameters influence the axial, lateral and torsional responses. Conclusion: The results obtained through this study are useful in the design of the spiral bevel gear set.

The present work investigates the mechanical responses of additively manufactured 17-4 PH Stainless Steel systematically using finite element method (FEM). Different simulations of tensile tests at room and elevated temperatures are performed on smooth and notched specimens for calculating the parameters of the Johnson-Cook material and damage model. The tensile strength of the 17-4 PH SS alloy notch bar is higher than the smooth bar at room temperature. ABAQUS (Explicit) is used for all FE calculations. Experimental data was used as input to perform all the elastic–plastic simulations in both 2D and 3D through the ABAQUS 6.14 software. The observed simulation results were correlated with the available literature. Strain rate and temperature dependent mechanical properties of AM 17-4 PH stainless steel in different processing conditions are also investigated in this study.

Rapid urbanization has caused a worldwide increase in the discharge of wastewater effluent. Although Nepal has a noteworthy history of wastewater management, progress in this field has been hindered by persistent issues. These problems encompass insufficient sewer coverage, deficient treatment and sludge disposal facilities, inadequate treatment infrastructure, lack of coherent institutional frameworks, and a lack of comprehensive planning. This review provides a glimpse into Nepal’s current urban wastewater landscape while also offering a concise historical overview of its wastewater management trends. The study gathered data, information from government organizations, as well as related research, review articles, and reports from 1999 to 2023. Our findings reveal that more than 85% of urban households in Nepal rely on onsite sanitation, with limited access to septage treatment facilities. The ratio of wastewater treatment to generation is disconcertingly low, further emphasized by the concentration of centralized treatment plants in the capital city. This low ratio underscores the inadequacy of the existing wastewater system and the novice approaches of the government, which contribute to the poor sewerage facilities in Nepal. This study unequivocally highlights the imperative need for functional and institutional hierarchy emphasizing local communities, substantial changes in resource allocation, governance practices, and technical infrastructure.

Thermoelectric textiles, constructed from thermoelectric materials and fabric, offer unique advantages compared to other types as they facilitate thermal energy harvesting from the human body and conform exceptionally well to dynamic body curves. This underscores their potential for on-body applications in electricity generation. In this investigation, we present a tellurium-free polymer-based textile thermoelectric prototype manufactured through a cost-effective method known as the solution drop-casting process. Two organic polymers, PEDOT:PSS and PVDF, are judiciously employed at optimized concentrations. At 300 K, the resulting PEDOT:PSS + PVDF/fabric thermoelectric film could exhibit an impressive output power factor of 60 nW/mK2. The processed thermoelectric film could retain its electronic properties after 500 bending cycles, which confirms its extraordinarily flexible nature. When subjected to a temperature gradient of 35 K, the textile thermoelectric prototype could generate a noteworthy output voltage and power of 3.8 mV and 2.7 nW, respectively, at 300 K. Importantly, when in contact with a human wrist and subjected to a temperature difference of ∼3 K, the prototype produced a 0.2 mV output voltage, which is reliable. Above all, the prototype exhibited an outstanding output voltage of approximately 13 mV, when its cold-end and hot-end were at 236 and 277 K, respectively. This corroborated the compatibility and superior energy generation performance of the investigated textile thermoelectrics under cold environmental conditions. Our study emphasizes the feasibility of Te-free, nontoxic polymer-based textile thermoelectric fabric for power generation using the human body and other low-grade heat available below and at room temperature.

Propylene glycol (or) 1,2-propanediol (1,2-PD) is an important polyol widely used for pharmaceuticals, polyester resins, paints, cosmetics, antifreeze, etc. Sucrose has emerged as a promising feedstock to produce 1,2-PD, as indicated by recent research findings. Graphitic carbon nitride (g-C3N4/gCN) was synthesized by using different crucibles. Ni-Mo was loaded on different g-C3N4 supports via the wetness impregnation method for sucrose hydrogenolysis. Effects of different g-C3N4 supports were studied. Catalysts with varying Ni (x = 0-8 wt %) and Mo (y = 0-15 wt %) contents were characterized using XRD, BET, XPS, FE-SEM, Py-FTIR, HR-TEM, TPD (CO2)and Raman spectroscopy. An attempt was made on sucrose conversion into 1,2-PD using a Ni-Mo/g-C3N4 catalyst. The catalyst containing 8% Ni and 10% Mo on Gr-gCN exhibited the best performance, achieving complete sucrose conversion with a 76% yield of 1,2-PD under mild reaction conditions. The presence of highly dispersed nanoparticles and the nature of graphitic carbon nitride help improve the reactions’ yield by allowing reactions at lower temperatures, reducing the occurrence of side reactions, and increasing recycling rates. A straightforward approach to material preparation, coupled with the exceptional dispersion of metal nanoparticles, paves the way for a novel platform for biomass conversion.

Blast Wave Simulator (BWS) is a form of shock tubes used to generate shock waves with a typical Friedlander profile. In a BWS, the samples are tested in reflective and diffractive modes. In reflective mode, wave reflections from the shock tube’s closed-end cause secondary loading in the specimen, which limits the suitability of BWS for testing the long-term dynamic response of the specimens since the secondary loading will affect the actual response. This study attempts to develop a reflected wave eliminator (RWE) fixture for an existing BWS facility to attenuate the peak positive overpressure of the reflected waves. The RWE used in this study is a self-opening flap that remains stationary during primary wave traversal, and it opens completely before the arrival of reflected waves in a closed-end shock tube. This study investigated the efficiency of the RWE for different shock strengths. The RWE reduced the peak overpressure up to 55.37% and 13.06% for strong and weak shock cases defined in this study. So, the efficiency of the RWE for a particular shock strength depends upon the mass of the flap. Our future study will focus on developing an adjustable mass flap to achieve the optimal flap opening rate for different strengths. With a properly designed RWE, the effects of secondary loading on the specimen in a closed-end shock tube can be significantly reduced.

Objective: Rolling element bearings are an essential part of rotating machinery. Sudden bearing failure may lead to catastrophic machine failure. Early bearing fault detection is essential to avoid machine failure. Vibration data received from bearings typically contain impulsive fault information. The characteristics acquired from the vibration signals generated by bearings are primarily used to identify bearing defects. The derived features might not be able to accurately pinpoint the failure’s timing due to background noise in the observed vibration signal. External noise reduction from the vibration signal is essential for extracting important features for effective fault diagnosis. A helpful de-noising method at present is variational mode decomposition (VMD). However, the VMD method alone may not eliminate the noise from the vibration data. Methods: The present work proposes a methodology for noise reduction combining VMD and an optimized Morlet filter. Initially, the signal is split using the VMD approach into various intrinsic mode functions (IMF), and the most efficient IMF is chosen using the maximum kurtosis criterion. Next, the golden ratio optimization method (GROM) based Morlet wavelet filter is applied to the effective IMF for reducing unwanted noise. The convolutional neural network (CNN) technique is then employed to identify the bearing defects. Conclusion: The proposed approach is tested upon bearing simulation datasets, bearing experimental datasets, gearbox experimental datasets, and sound datasets to validate its efficiency. The validation of the proposed algorithm using gear and sound datasets indicates its broad applicability.

Purpose: Surface electromyography (sEMG) is a non-invasive technique to characterize muscle electrical activity. The analysis of sEMG signals under muscle fatigue play a crucial part in the branch of neurorehabilitation, sports medicine, biomechanics, and monitoring neuromuscular pathologies. In this work, a method to transform sEMG signals to complex networks under muscle fatigue conditions using Markov transition field (MTF) is proposed. The importance of normalization to a constant Maximum voluntary contraction (MVC) is also considered. Methods: For this, dynamic signals are recorded using two different experimental protocols one under constant load and another referenced to 50% MVC from Biceps brachii of 50 and 45 healthy subjects respectively. MTF is generated and network graph is constructed from preprocesses signals. Features such as average self-transition probability, average clustering coefficient and modularity are extracted. Results: All the extracted features showed statistical significance for the recorded signals. It is found that during the transition from non-fatigue to fatigue, average clustering coefficient decreases while average self-transition probability and modularity increases. Conclusion: The results indicate higher degree of signal complexity during non-fatigue condition. Thus, the MTF approach may be used to indicate the complexity of sEMG signals. Although both datasets showed same trend in results, sEMG signals under 50% MVC exhibited higher separability for the features. The inter individual variations of the MTF features is found to be more for the signals recorded using constant load. The proposed study can be adopted to study the complex nature of muscles under various neuromuscular conditions.

The east coast of India is highly prone to devastating winds, torrential rainfall, and storm surges caused by tropical cyclones. The storm surge is affected by ocean basin characteristics involving the width and slope of the continental shelf. The bed roughness plays a major role in surge formation. The east coast of India is characterized by a broader shelf in the north and a narrow shelf in the south. This paper uses a hybrid Finite Volume Method–Finite Element Method based Shallow water equation (SWE) solver to predict the storm surges during different cyclone events, and the roughness parameter Manning’s n is used in bed friction calculations. The bottom friction coefficient parameterization involving bed roughness is used to calibrate the resistance to flow in the numerical model. The calibration exercises are carried out with different values of n for each surge simulations for different cyclones to predict the surface elevation. Different statistical parameters against the measured values are used to analyze the impact of varying n values on predicted surge levels, and the most suitable n value is carefully chosen. The relationship between n and the bed slope is established as an expression, to replace the formulations involving Manning’s n, thereby minimizing the usual computational efforts. The performance of the novel bed friction formulation involving the physical parameter in bed slope is demonstrated through statistical evaluations.

Leaders and organizations worldwide faced tough decisions while responding to the complications of operating during the pandemic, COVID-19. Schools were not exempt from this mayhem. The rapid need for transition to virtual classrooms stressed teachers even as they battled with the virus. Teachers required a compassionate leader during the crisis. With stress at an all-time high, accompanied by uncertainty about the future, compassionate leadership was a crucial factor to navigate through such crises. Regarding compassionate leadership of school principals, researchers are yet to thoroughly study its conceptual and empirical relationship with teacher attitudes and behaviours. Although evolving research addresses the outcomes of compassionate leadership, little is known about how compassionate school principals impact work attitudes and behaviours of teachers. Hence, we present a broad theoretical framework of how compassionate leadership of school principals influences teacher work attitudes and job performance. Mainly, we analyse the relationships between compassionate leadership and teachers’ resilience, work engagement, psychological well-being, and job performance. We base our study on trust, positive emotions, and self-efficacy theories to explain the compassionate leadership process. We advance research propositions and discuss the implications for future research and compassionate leadership practices at schools.

Incubators play an instrumental role in nurturing startups and creating a vibrant ecosystem. But as the ecosystem evolves, incubators also need to reinvent themselves to stay relevant. Against a burgeoning startup ecosystem in India, this roundtable deliberates on the future of incubation. The experts discuss what services incubators should offer, how they should measure their impact and how they can become financially sustainable.

Commercial utilisation of additively manufactured components would often need post-process machining to meet the geometric tolerances. It is of vital significance to understand the machining behaviour of the material manufactured by additive route compared to the traditional routes. This work investigates the influence of processing variables on the dry drilling performance of the Ti6Al4V produced by electron beam melting (EBM). The machinability behaviour is investigated by analysing the cutting force, chip morphology, tool wear, form error, hole size and burr formation. When the spindle speed increases, three varying trends in force were observed for the investigated conditions (3000–5000 RPM). The cutting force increased when spindle speed increased from 3000 to 3500 RPM. Further, it decreased between 3500 and 4500 RPM and increased subsequently. Smooth uniform spiral chips were evident only at low spindle speed (3000 RPM), and short distorted chips were formed at high spindle speed (4500–5000 RPM), indicating favourable and non-favourable machining conditions, respectively. It was also noticed that thin, soft chips with less stiffness were formed at the combination of low feed rate (40 mm/min) and high spindle speed, which led to a 62% reduction in cutting force. Hole diametric deviation indicated that mostly oversized holes were formed with a minimum deviation of 1.8% at 3000 RPM/120 mm/min. At high spindle speed, the crown burr formation was evident irrespective of the feed rate, which is attributed to the high-temperature effect. Overall, a better surface quality of the hole was found at low spindle speed (3000–3500 RPM) and a feed rate of 40–120 mm/min.

The utilization of hollow glass particle-filled fiber-reinforced composites in marine applications necessitates a proper understanding of their behavior when exposed to moisture environments. In this study, the glass fiber-reinforced composites reinforced with 0%–30% volume fraction of glass microspheres were fabricated and immersed in seawater and distilled water conditions for monotonic tensile and flexural testing. The degradation mechanisms were analyzed by dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Moisture absorption results showed an increasing trend with the inclusion of glass microspheres. A decline in glass transition temperature and storage modulus was observed as a result of moisture absorption. The tensile results of the specimens exhibited a decrease of 13% and 9% in distilled water and seawater solution, respectively when compared with unaged samples, respectively. The flexural results of the aged composite specimens demonstrated a reduction of 24% and 11% in distilled water and seawater solution, respectively when compared with unaged samples. The findings also show that the influence of moisture on the modulus is less pronounced compared to its effect on strength under both environmental conditions. The micrograph results revealed a notable deterioration of the glass microsphere and the fiber/matrix interface in the moist environment. Highlights: Water absorption increases with the addition of glass microspheres. Microsphere degradation and fiber/matrix debonding are the governing mechanism. Retained 89% of tensile strength of their initial properties after exposed in sea water. Increase in microsphere contents decreases the tensile and flexural strength.

The Lightweight, Multi-speaker, Multi-lingual Indic Text-to-Speech (LIMMITS'23) challenge is organized as part of the ICASSP 2023 Signal Processing Grand Challenge. LIMMITS'23 aims at the development of a lightweight, multi-speaker, multi-lingual Text to Speech (TTS) model using datasets in Marathi, Hindi, and Telugu, with at least 40 hours of data released for each of the male and female voice artists in each language. The challenge encourages the advancement of TTS in Indian Languages as well as the development of techniques involved in TTS data selection and model compression. The 3 tracks of LIMMITS'23 have provided an opportunity for various researchers and practitioners around the world to explore the state-of-the-art techniques in TTS research.

The Split Hopkinson Pressure Bar (SHPB) technique is most commonly used to study the dynamic behaviour of materials when subjected to high-speed impact. The influence of the specimen size and shape plays a predominant role in estimating the flow stress behaviour of the Al 2014 alloy that is widely used in aerospace applications. In the present study, numerical analysis is carried out on three specimen shapes—Circular, Square, Demi-bull-nosed; and the corresponding L/D ratios of 0.5, 1 and 1.5 are estimated for the various specimen shapes. Flow stress–strain curves are compared with each other and found that the demi-bull-nosed specimens have shown moderate stresses, which could be a substitute for the circular specimens during their non-availability. These specimens were further analysed for their dynamic behaviour for the three strain rates of 2857.1/s, 5714.3/s and 8571.43/s. The variation of L/D or L/S ratios revealed that the lower ratio of 0.5 resulted in higher flow stresses with large deformation behaviour. The simulation results were further validated with the available experimental results of compression SHPB, which are in tandem with each other.

An efficient approach for the synthesis of chiral pyrrolo[1,2-d][1,4]thiazine-2-carbaldehydes is achieved via formal 1,3-dipolar cycloaddition/rearrangement reactions of benzothiazolium salt and α,β-unsaturated aldehydes, utilizing an asymmetric organocatalyst. This process results in the formation of fluorescent, highly enantioenriched chiral molecules with three contiguous stereogenic centers, one of which is a chiral quaternary center, with excellent yields and enantio- and diastereoselectivity. A computational study demonstrated the understanding of the reaction mechanism. The synthetic utility of this protocol was successfully employed for gram scale synthesis. Fluorescent and in silico studies showed the application of the present methodology.

Genome-scale metabolic models (GEMs) of Chinese hamster ovary (CHO) cells are valuable for gaining mechanistic understanding of mammalian cell metabolism and cultures. We provide a comprehensive overview of past and present developments of CHO-GEMs and in silico methods within the flux balance analysis (FBA) framework, focusing on their practical utility in rational cell line development and bioprocess improvements. There are many opportunities for further augmenting the model coverage and establishing integrative models that account for different cellular processes and data for future applications. With supportive collaborative efforts by the research community, we envisage that CHO-GEMs will be crucial for the increasingly digitized and dynamically controlled bioprocessing pipelines, especially because they can be successfully deployed in conjunction with artificial intelligence (AI) and systems engineering algorithms.

The aim of this paper is to describe the equivariant and ordinary Grothendieck ring and the equivariant and ordinary topological (Formula presented.) -ring of flag Bott manifolds of the general Lie type. This will generalize the results on the equivariant and ordinary cohomology of flag Bott manifolds of the general Lie type due to Kaji, Kuroki, Lee, and Suh.