Indian Institute of Technology Bombay

We present the theory and implementation of a relativistic third-order algebraic diagrammatic construction [ADC(3)] method based on a four-component (4c) Dirac–Coulomb Hamiltonian for the calculation of ionization potentials (IPs), electron affinities (EAs), and excitation energies (EEs). Benchmarking calculations for IP, EA, and EE were performed on both atomic and molecular systems to assess the accuracy of the newly developed four-component relativistic ADC(3) method. The results show good agreement with the available experimental data. The Hermitian nature of the 4c-ADC(3) Hamiltonian, combined with the perturbative truncation of the wave function, offers significant computational advantages over the standard equation-of-motion coupled-cluster approach, particularly for property calculations. The method’s suitability for property calculations is further demonstrated by computing oscillator strengths and excited-state dipole moments for heavy elements.

This study addresses the risks arising from the inherent geological variability and ground uncertainties that affect the face stability during tunnel boring machine (TBM) operations. It used the data from Kolkata East–West Metro UG-1 Package to predict the relationships between the tunnel face stability and the properties of soils ahead of the TBM. It considered the cutterhead-soil interaction during the mechanised shield tunnelling and used the load transferred from the tunnel face to the cutting wheel as input. A statistical multi-parametric regression and hypothesis testing were then done on the modified relationships. These correlations can reasonably assess, in real-time, the in situ properties ahead of the TBM for the prediction of tunnel face stability. The application could optimise the operational cost by bringing in a degree of automation in the TBM operations, by assessing the face support pressure as function of the boring parameters.

Induration is a thermal treatment process wherein the green pellet properties are enhanced for subsequent reduction processes such as blast furnace and DRI production. During induration, the pellet essentially undergoes (i) physical change, that is, particles sinter with each other imparting strength to the pellet and (ii) chemical change by which phase change occurs either due to reduction/oxidation or thermal decomposition. Both these changes are interdependent. In case of induration of magnetite pellet, the exothermic oxidation of magnetite to hematite generates heat within the pellet. However, for the induration of hematite pellets carbon in the form of coke breeze is added in the green pellet mix to aid heat generation by combustion within the pellet. In this paper, the sintering of single hematite pellet is investigated isothermally using optical dilatometer. Sintering kinetics is deduced for the pellet and the effect of coke addition on sintering kinetic parameters has also been investigated. The shrinkage data, expressed in terms of sintering ratio, from the optical dilatometer is sufficient to capture sintering kinetic. The extent of sintering under isothermal condition as a function of time can be expressed in terms of power law relation as Ktⁿ. The constant K as function of sintering temperature, as sintering being a thermally activated process, can be described using Arrhenius equation. The kinetic triplet namely, time exponent(n), pre-exponential factor(kꞌ) and the activation energy(Q) are determined for pellets with no coke to 2 wt% coke addition. This paper presents insight into the sintering mechanism of hematite pellet.

This study proposes a framework to evaluate probabilistic seismic risk of buildings in regions exposed to both crustal and subduction earthquakes. Ground motions from subduction earthquakes are typically longer in duration, causing higher damage to structure due to increased inelastic demand as compared to ground motions from crustal earthquakes having the same peak intensity. The increased vulnerability to structural damage from subduction earthquake ground motions needs to be accounted for in seismic loss assessment studies. This study investigates the same for India. The north and northeast of India are exposed to both crustal and continental subduction seismic sources, and Peninsular India is exposed to crustal seismic sources. Nonlinear analytical models are developed for a set of modern Indian code-compliant reinforced concrete special moment frame buildings located at 20 different sites in India. Incremental dynamic analysis (IDA) of building models using spectrally equivalent ground motions from crustal and subduction earthquakes is used for developing tectonic-region-type-specific (crustal and subduction) building vulnerability functions. The cumulative damage index is used as the engineering demand parameter to capture the increased inelastic demand from subduction earthquakes on buildings. For seismic risk assessment, the total seismic hazard at a site is separated into its contribution from crustal and subduction sources and combined with respective building vulnerability functions. The seismic risk of buildings is quantified by average annual loss ratio (AALR) through event-based probabilistic seismic risk analysis. For buildings located in high seismic zones of India, this study finds that AALR can be up to 40% higher on average as compared to studies not accounting for increased building vulnerability from subduction earthquakes.

Aim This study aimed to examine the efficacy of the Coping Cat program, a CBT intervention, for Indian children (11–13 years) with high anxiety. Methodology A total of 240 children were screened, and 120 children with high anxiety were randomly assigned to either a treatment group ( n = 60) or a control group ( n = 60). The Spence Children’s Anxiety Scale (SCAS), Strength and Difficulties Questionnaire (SDQ), and Child Anxiety Impact Scale (CAIS) were used to assess anxiety symptoms and related outcomes. Systematic random sampling was employed to select participants. Intervention The therapeutic process consisted of a modified CBT protocol, comprising 16 sessions of 40–45 minutes each. The Coping Cat program was specifically designed to address anxiety symptoms in children. Data Analysis A linear mixed-effects model was used to analyze the data, accounting for both fixed effects (e.g., time and intervention) and random effects (e.g., individual differences). This approach was particularly suited for the repeated-measures design. A follow-up study was conducted one year after the intervention to assess its long-term effects. Results Significant differences were observed between the treatment and control groups, indicating the efficacy of the Coping Cat program in reducing anxiety symptoms. Notably, treatment gains were maintained at the one-year follow-up. Conclusion: The findings suggest that the Coping Cat program is an effective CBT-based intervention for reducing anxiety symptoms in highly anxious children. Conclusion The results indicated the efficacy of Coping Cat CBT in highly anxious young children.

This study aims to characterize the range of eddy sizes in grid-generated turbulence within a three-dimensional framework, examining eddy structures arising from interactions between the turbulent flow and a rigid boundary. The study utilizes three-dimensional velocity time-series, processed within a time-averaged framework, to examine both large-scale and small-scale turbulent flow characteristics induced by the passive grid. The integral length scale (in the stream-wise, lateral, and vertical directions) is calculated using the auto-correlation function, while the Taylor length scale (also in the stream-wise, lateral, and vertical directions) is determined using the velocity gradient approach. This approach allows us to capture and compare eddy dynamics across different mesh configurations. The integral and Taylor's length-scale anisotropy are also presented to understand the directional characteristics of the turbulent structures (eddy sizes) at the downstream locations of the grid. The results demonstrate that as the grid's mesh size increases, fluctuations in both the stream-wise and vertical directions, along with turbulence kinetic energy, decrease near the boundary regions. The stream-wise fluctuations significantly increase in both the near-field and far-field regions for all three mesh sizes when compared to that for the no-grid case. The deviations between the surrogates of dissipation rates in the near-field and far-field regions are more pronounced when compared to those in locally isotropic conditions due to increased shear and the resulting anisotropy in the flow. The anisotropy invariant map of the turbulent dissipation rate tensor and Reynolds stress tensor at downstream positions reveals that turbulent fluctuations are predominantly aligned along one direction.

The integration of immersive Virtual Reality (I-VR) technology in education has emerged as a promising approach for enhancing learning experiences. There is a handful of research done to study the impact of I-VR on learning outcomes, comparison of learning using I-VR and other traditional learning methods, and the impact of values such as haptic sensation, and verbal and non-verbal cues on the learning outcomes. However, there is a dearth of research on understanding how learning is happening from the perspective of the behavior of the learners in the Virtual Reality Learning Environment (VRLE). To address this gap, we developed an Interaction Behavioral Data (IBD) logging mechanism to log all the interaction traces that constitute the behavior of the learners in a Virtual Reality Learning Environment (VRLE). We deployed the IBD logging mechanism in a VRLE used to learn electromagnetic induction concepts and conducted a study with 30 undergraduate computer science students. We extract the learners' actions from the logged data and contextualize them based on the action features such as duration (Long and Short), and frequency of occurrence (First and Repeated occurrence). In this paper, we investigate the actions extracted from logged interaction trace data to understand the behaviors that lead to high and low performance in the VRLE. Using Epistemic Network Analysis (ENA), we identify differences in prominent actions and co-occurring actions between high and low performers. Additionally, we apply Differential Sequence Mining (DSM) to uncover significant action patterns, involving multiple actions, that are differentially frequent between these two groups. Our findings demonstrate that high performers engage in structured, iterative patterns of experimentation and evaluation, while low performers exhibit less focused exploration patterns. The insights gained from ENA and DSM highlight the behavioral variations between high and low performers in the VRLE, providing valuable information for enhancing learning experiences in VRLEs. These insights gained can be further utilized by the VR content developers to o develop adaptive VR learning content by providing personalized scaffolding leading to the enhancement in the learning process via I-VR

In classical game theory, the players are assumed to be rational and intelligent, which is often contradictory to reality. We consider more realistic behavioral game dynamics where the players choose actions in a turn-by-turn manner and exhibit two prominent behavioral traits --- α-fraction of them are myopic who strategically choose optimal actions against the empirical distribution of the previous plays, while the rest exhibit herding behavior by choosing the most popular action till then. The utilities are realised for all, at the end of the game, and each player gets to play only once. Our analysis focuses on scenarios when players encounter two possible choices, common in applications like participation games (e.g., crowd-sourcing) or minority games. To begin with, we derive the almost sure mean-field limits of such dynamics. The proof is constructive and progressively narrows down the potential limit set and finally establishes the existence of a unique limit for almost all sample paths. We argue that the dynamics at the limit is captured by a differential inclusion (and not the usual ordinary differential equation) due to the discontinuities arising from the switching behavioral choices. It is noteworthy that our methodology can be easily modified to analyse the avoid-the-crowd behavior, in place of herding behavior. We conclude with two interesting examples, named participation game and routing game, which encapsulate several real-life scenarios. Interestingly, for the first game, we observe that the game designer can induce a higher level of participation in an activity with smaller reward, by leveraging upon the presence of herding players.

This study investigates the natural frequencies of a flexible string moving axially within a fluid using an approximate analytical approach. The motion of such axially moving string or beam is governed by equations incorporating centripetal and Coriolis acceleration components. When these continua travel through a fluid, they are subjected to various fluid forces. Due to such forces, the spatially varying coefficients appear in the governing differential equation, which complicates the derivation of closed-form solutions. In this paper, these fluid forces are initially modeled as a distributed follower force with viscous damping. Approximate closed-form expressions for natural frequencies are derived using an asymptotic technique for an axially moving string subjected to a distributed follower force. This approach is further applied to determine the natural frequencies of the traveling string, accounting for all viscous fluid forces.

The present article focuses on a unique continuation result for certain weighted ray transforms, utilizing the unique continuation property (UCP) of the fractional Laplace operator. Specifically, we demonstrate a conservative property for momentum ray transforms acting on tensors, as well as the antilocality property for both weighted ray and cone transforms acting on functions.

Knowledge of the kinetics of petroleum pitch pyrolysis is crucial to improve and optimize the design of pyrolysis reactors, gasification reactors, and circulating fluidized bed combustors (CFBC) to use as feedstock. Thermogravimetric analysis (TGA) was performed to understand the kinetic aspects of the pitch pyrolysis. The isoconversional Friedman, Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Starink methods were used to calculate the divergence of activation energy and mechanistic understanding of the complex nature of pitch pyrolysis. The mean activation energies were 176.46, 178.79, 176.79, and 189.90 kJ mol−1 for the KAS, FWO, Starink, and Friedman methods. The three-dimensional diffusion model, followed by the pyrolysis process, was determined using model-based Coats–Redfern and Criado methods. The linear relationship of the pre-exponential factor and the activation energy was obtained through the kinetic compensation effect (KCE) relationship. The positive values of enthalpy and Gibbs Free energy confirmed the endothermic nature of the pitch pyrolysis. The positive to negative variation of entropy was observed because of the complicated nature of the pitch pyrolysis process. During pyrolysis, the residue's surface morphology detected pores, cracks, and mesophase formation in scanning electron microscope (SEM) analysis, and sulfur, vanadium, and nickel were present in energy-dispersive spectrometer (EDS) analysis of the residue. Fourier transform infrared spectroscopy (FTIR) analysis of the sample and residue showed an intermediate cross-link reaction, which led to the formation of a mesophase coke structure in the pyrolysis process.

Regioselective and enantioselective C‐H functionalization is a valuable method for synthesizing chiral and complex molecules. However, it often requires large amounts of toxic oxidants and high temperature, making it environmentally and economically adverse. Additionally, these traditional approaches generally suffer from regioselectivity and enantioselectivity issues. To overcome these limitations, a new mechanism is needed to control both of these simultaneously. Herein, we report the first Pd catalyzed regioselective distal and atroposelective olefination of simple arenes/biaryls via an electrooxidative reaction pathway. This unique electro‐oxidative strategy with Pd(II) catalysis demonstrates unprecedented access to ‘regio‐resolved’ reactions, furnishing chiral molecule synthesis under dynamic kinetic resolution without the conventional requirement of metal‐based oxidants and thermal energy. Both electroanalytical studies and DFT calculations suggest the involvement of a Pd(II)/Pd(IV) catalytic cycle via a crucial Pd(III) intermediate that initiates both the distal and atroposelective olefination reactions.

The “oxo‐wall” is a well‐established concept in the area of bioinorganic chemistry, which refers to the instability of the terminal metal‐oxo complexes in the +4 oxidation state, with tetragonal C4v symmetry beyond group 8 elements. This leads to a diverse and highly reactive chemistry of Co‐oxo complexes, as evidenced in the literature, ranging from challenging C−H bond activation to efficient water oxidation. Despite extensive research on first‐row terminal metal‐oxo complexes and the “oxo‐wall” concept, studies correlating the reactivity of these species across the periodic table remain scarce. In this work, using a combination of DFT and ab initio CASSCF calculations, we have explored the structure, bonding, and reactivity of [MIV/V(15‐TMC)(O)(CH3CN)]m+ (M= Mn, Fe and Co) species. Our study reveals several intriguing outcomes: (i) while existing literature typically indicates the presence of either CoIV=O or CoIII–O• species beyond the wall, we propose a quantum mechanical mixture of these two species (termed as CoIV=O CoIII–O•), with the per cent of mixing dictated by ligand architecture and symmetry considerations; (ii) we observe that the oxyl radical character increases beyond the wall, correlating with larger Ntrans‐M−O tilt angles; and (iii) we identify an inverse relationship between the percentage of M–O• character and the kinetic barriers for C−H bond activation. These findings offer a new perspective on the roles of oxidation states, spin states, and the nature of the metal ion in reactivity.