The Influence of Geotechnical Parameters on Sinkhole Subsidence and Its Model Development for Underground Coal Mines in Central India

Journal of Mining Science - Excavations in shallow depth and the presence of weak overlying rock may disturb the strata conditions due to which caving start and creates a cavity in the subsurface...     

Solution of transient heat transfer in graded-material fins of varying thickness under step changes in boundary conditions using the Lattice Boltzmann Method

Graded materials (GM) possess superior thermo-mechanical properties, which are not feasible to obtain with homogeneous materials (HM), and hence in this paper, the transient response of a longitudinal fin of varying geometry made up of GM is reported. The temperature-dependent convection coefficient and heat generation parameters are considered to account for real-world high-temperature applications of fins. Fin material properties such as density and specific heat remain constant while thermal conductivity is assumed to vary axially based on four different physically possible variations namely, linear, quadratic, power, and exponential variations. The typical nonlinear differential equation obtained for fins was solved by using a mesoscopic scale-based particle tracking method called the Lattice Boltzmann method. The Lattice Boltzmann solver has been implemented in form of an in-house MATLAB code and validated with existing results, thereafter it is developed for solving the foregoing problems. The results obtained are reported for rectangular, triangular, convex, and concave profiles under step change in base temperature and base heat flux. The performance of graded fins is investigated in terms of time required to attain steady-state and fin tip temperature which are inherent design parameters in the case of the transient fin. Inhomogeneity index and profile function have a significant effect on the performance of fin in terms of resistance to heat flow. Hereby, in comparison with HM fins, GM fins have lower resistance to heat flow irrespective of fin profiles. Concurrently, comparative analysis for fins of different profiles made of HM and GM is also done to facilitate the designer in selecting the most appropriate fins.     

Analyzing the Effects of Milling and Sintering Parameters on Crystalline Phase Evolution and Mechanical Properties of Al86Ni8Y6 and Al86Ni6Y4.5Co2La1.5 Amorphous Ribbons

In the present study, Al₈₆Ni₈Y₆ and Al₈₆Ni₆Y_4.5Co₂La_1.5 bulk amorphous nanocomposites were synthesized by spark plasma sintering of milled melt spun ribbon particles. The as-cast ribbons were of near amorphous nature with minute amount of FCC Al embedded in the amorphous matrix. Milling of the ribbons resulted in partial devitrification due to mechanical crystallization. The milled ribbon particles were sintered in the temperature and pressure range of 300-500 °C and 500-700 MPa, respectively. It was observed that nominal amount of amorphous phase was retained at 500 °C and 500 MPa. With increase in sintering pressure and decrease in sintering temperature, the amount of crystalline phase evolution decreased, and maximum amount of amorphous phase was retained at 300 °C and 700 MPa. The microstructure consisting of amorphous phase embedded with hard intermetallic phases led to increase in the nanohardness of Al₈₆Ni₈Y₆ and Al₈₆Ni₆Y_4.5Co₂La_1.5 as-cast ribbons from 3.26 ± 0.59 GPa and 3.81 ± 0.58 GPa to 6.06 ± 0.70 GPa and 6.14 ± 0.82 GPa, respectively, for the corresponding consolidated amorphous nanocomposite. Microhardness of the three and five component system bulk samples was 4.19 ± 0.13 GPa and 3.6 ± 0.13 GPa, respectively.     

Average bit error probability performance of intelligent reflecting surface-aided wireless communications over Hoyt fading

In this article, the performance of a wireless communication system with an intelligent reflecting surface (IRS) panel installed between the transmitter and receiver is studied. The channel is considered to be the Hoyt faded and additive white Gaussian noise. Closed-form expressions for average bit error probability (ABEP) for both coherent Gray-coded rectangular quadrature amplitude modulation and non-coherent modulation schemes are presented. We apply the moment-generating function-based method for the derivation. In addition, asymptotic ABEP expressions are also obtained. Using asymptotic ABEP expressions, we obtained diversity order which is a function of the number of IRS elements. The effect of the number of IRS elements and fading parameters on the ABEP is studied. The ABEP performance improves with an increase in the number of reflecting elements but degrades with an increase in the fading severity. The accuracy of each analytical ABEP expression is verified by the simulation of the system considered herewith.     

Synthesis and characterization of novel Al(III)-metallopolymer and its application as a non-volatile resistive memristive material

In this study, Al(III)-metallopolymer is synthesized with our previously reported ligand to understand the difference in the interaction of the reported ligand with transition metal ions (Fe(II) and Cr(II) ions) and smaller cationic radius main group metal ion. Al(III)-metallopolymer is thoroughly characterized by different analytical techniques to understand the structure–property relationship. Surface morphological analyses reveal the formation of long nano-fiber strands on the respective substrates. This polymer has shown reversible redox behavior, which is ligand centric as no d-orbitals are available on the central metal ion for the electron push-pull mechanism. Al(III)-metallopolymer is fluorescent active, and it is shown a reversible change in absorption spectrum on the application of the appropriate potential. This ligand-based redox-switching also generates a bistable state when a metal–insulator(thin film of polymer)-metal sandwich device is probed in between ±1 V, and it is stable in the ambient condition to sustain several flip-flop cycles without any degradation for 10³ s as observed from the experimental data. This work enlightens a new metallopolymer with a low value of SET-RESET voltage and a long retention time for the future memristive device, which can operate at very low voltage compared to conventional Si-based memory chips.     

Biologically Sensitive FETs: Holistic Design Considerations from Simulation,Modeling and Fabrication Perspectives

Silicon - The conceptualization of biomolecule sensing accomplished by field effect transistor (FET) devices have been attracting substantial contemplation for over twenty years owing to the...     

Se⋅⋅⋅O/S and S⋅⋅⋅O Chalcogen Bonds in Small Molecules and Proteins: A Combined CSD and PDB Study

The importance of selenium-centered noncovalent chalcogen bonds represented as Se⋅⋅⋅A (A=O/S) has been explored for short directional contacts in small molecules and proteins. In addition, S⋅⋅⋅O centered contacts have been analyzed. Computational analyses involving the quantitative assessment of the associated energetics, the molecular electrostatic potentials (MEP), and electron density derived topological parameters, namely, quantum theory of atom in molecules (QTAIM) analyses, and NBO (natural bond orbital) based calculations, have been performed to unequivocally establish the strength, stability, and attractive role of chalcogen bonds in the solid-state. This investigation has been performed in molecules from both the Cambridge Structural Database (CSD) and Protein Data Bank (PDB). Thus futuristic materials may be designed keeping in mind the significance of these interactions, including their relevance in biology.     

Maximum power point tracking controller implementation in multiple input converter for effective solar energy harvesting using maximum power point resistance method

Solar energy is widely acknowledged as one of the most promising renewable energy sources for addressing future electrical energy demands. Photovoltaic modules (PVms) convert solar energy into electrical energy and are highly sensitive to nonlinear changes in environmental circumstances, which in turn affect the generation of electricity from the PVms. The module-level maximum power point tracking (MPPT) of PVms using multiple input converters (MICs) is the effective and cost-efficient method among all the methodologies and techniques. MICs, on the other hand, suffer from a cross power-sharing difficulty due to their modular design, which implies that the individual cells that make up the device impact on each other's power-sharing operation. The solution to which have been ignored in the literature. The objective of this paper is to employ the maximum power point resistance (MPPR) approach to determine an appropriate duty ratio range for the proposed MIC while taking into consideration the cross effect of different cells. Steady-state, power loss, and efficiency analysis of the proposed MIC structure with less component count have been included. The proposed approach has been validated experimentally and further, a comparative analysis with recently reported various approaches has also been included to prove the suitability of the proposed approach.     

Dual image-based reversible fragile watermarking scheme for tamper detection and localization

Pattern Analysis and Applications - This study proposes an efficient dual image-based reversible fragile watermarking scheme (DI-RFWS) that can accurately detect and locate the tampering regions...     

Coalition theory based task scheduling algorithm using DLFC-NN model

Resource management and job scheduling are essential in today's cloud computing world. Due to task scheduling and users' diverse submission of large-scale requests, co-located VM instances negatively impacted the performance of leased VM instances. This workload further led to resource rivalry across co-located VMs. In order to address the aforementioned problems, numerous strategies have been presented, however, they fail to take the asynchronous nature of the cloud environment into account. To address this issue, a novel “CTA using DLFC-NN model” is proposed. This proposed approach combines the coalition theory and DLFC-NN techniques by including IRT-OPTICS for task size clustering, digital metrology based on ionized information (DMBII) for defect detection in virtue machines (VM), and the dynamic levy flight hamster optimization algorithm for processing time optimization of the clusters. However, the implementation of task scheduling in an online environment is limited by a number of presumptions or oversimplifications made by current scheduling systems. As a result, a unique coalition theory is applied to efficiently schedule activities. In addition, the DLFC-NN model is used to reduce resource consumption, span time, and be highly accurate and energy-efficient when working on both online and offline jobs. Nevertheless, while optimizing the clusters' overall execution time, earlier approaches only decreased the make-span time for task scheduling. However, the DLFC-NN model solves the computation problem by using a fully weighted bipartite graph and the pseudo method to determine the fitness of the least makespan time. The enhanced methodology used in this study reduces the scheduling cost and minimizes job completion times according to different task counts when compared to the existing techniques.