Gauranga Charan Samanta

Green production and effective inventory management are increasingly recognized as essential components for promoting sustainable practices across industries, benefiting both the economy and society. This study introduces a novel inventory management framework designed to address demand disruptions and environmental impacts by implementing advanced payment policies and investments in green technology in the context of the COVID-19 pandemic. First, we develop a two-warehouse inventory system for deteriorating products, featuring a finite capacity for the owned warehouse (OW) and sufficient capacity for the rented warehouse (RW) to ensureinventory availability during both short-term and long-term lockdown scenarios. Secondly, we consider a two-parameter Weibull distribution for non-instantaneous deterioration with partial backlogging. Given the uncertainty of market demand influenced by non-linear price sensitivity, we analyze inventory classification and optimal replenishment strategy under four discrete circumstances to reflect time-varying lockdown durations and demand fluctuations.The results indicate that green technology and advanced payment systems minimize supply chain risks and decrease carbon emissions. Numerical findings indicate maximum net earnings of 631.128 and 564.428 in scenarios 1 and 2, respectively, with green investments of 5 units; however, profits diminish with increased investments. Scenario 1 is more economical than Scenario 2 because of its reduced lockdown duration, leading to decreased holding and deterioration costs.Partial backlogging is the most lucrative and sustainable Economic Order Quantity approach in the presence of shortages. These findings underscore the significance of adaptive inventory systems and sustainable practices in strengthening supply chain resilience.This study provides actionable insights for businesses looking to optimize inventory management amidst demand disruptions while promoting environmental sustainability.

We investigate the global causal structure of the end state of a spherically symmetric marginally bound Lemaitre–Tolman–Bondi (LTB) (Lemaitre 1933 Ann. Soc. Sci. Brux. A 53 51, Tolman 1934 Proc. Natl Acad. Sci. USA 20 169–76, Bondi 1947 Mon. Not. Astron. Soc. 107 410) collapsing cloud (which is well studied in general relativity) in the framework of modified gravity having the generalized Lagrangian R + α R 2 in the action. Here R is the Ricci scalar, and α ⩾ 0 is a constant. By fixing the functional form of the metric components of the LTB spacetime, using up the available degree of freedom, we realize that the matching surface of the interior and the exterior metric are different for different values of α. This change in the matching surface can alter the causal property of the first central singularity. We depict this by showing a numerical example. Additionally, for a globally naked singularity to have physical relevance, a congruence of null geodesics should escape from such singularity to be visible to an asymptotic observer for infinite time. For this to happen, the first central singularity should be a nodal point. We here give a heuristic method to show that this singularity is a nodal point by considering the above class of theory of gravity, of which general relativity is a particular case.

Kim and Lee [Phys. Rev. D 63 (2001) 064014] studied charged wormholes and Morris–Thorne wormholes in the presence of scalar field using the concepts of general relativity. In this paper, we have also considered same wormholes affected with electric charge and scalar field and extended their study using the framework of [ ] gravity with [ ] gravity model, where [ ] and [ ] are constants. We have examined the possibility for minimization of the amount of exotic matter through energy conditions. Further, we have obtained the deflection angle, an important notion in gravitational lensing, by using strong field limit coefficients which may be helpful in the detection of wormholes.

This paper develops an inventory model considering a demand disruption and a linear price and time dependent demand. In this model, we analyze two possibilities and apply the FIFO dispatch policy. In the first scenario, the inventories of the owned warehouse (OW) get vacant after the lock-down relieves owing to a shorter lock-down duration, but in the second scenario, the inventories of the OW get vacant during the lock-down due to a longer lock-down duration. A two parametric Weibull distribution has been considered to mirror the real problems caused by deterioration. The study aims to minimize the total cost of a two-warehouse system during the lock-down time. Furthermore, sensitivity analysis was used to investigate the models' behavior. Taking into consideration actual conditions, this model might be useful in an emergency situation like the COVID-19 epidemic.

We explore an autonomous system analysis of dark energy models with interactions between dark energy and cold dark matter in a general systematic approach to cosmological fluids. We investigate two types of models such as local and non-local ones. In particular, a local form of interaction is directly proportional to only the energy density, while a non-local interaction is directly proportional to the energy density as well as the Hubble parameter. As a consequence, it is explicitly demonstrated that in both cases there exist the stability points in terms of cosmological parameters. This work aims at obtaining acceleration and stability using interaction models without modifying the matter or geometric component of the Universe.

In this paper, Morris Thorne wormholes are considered in the context of [ ] gravity. A shape function is defined as [ ], where [ ] is constant. The equation of state is considered as [ ] and [ ] function is derived. The wormhole solutions are obtained and energy conditions are examined. Further, the [ ] model is found to be consistent with local gravity tests and stability of cosmological perturbations and late-time de Sitter point. Cosmological evolution is also explored using Friedman-Robertson-Walker (FRW) metric in [ ] gravity.

In this paper, we considered the study of Friedmann–Robertson–Walker (FRW) model in the framework of [ ] gravity, an extension of symmetric teleparallel gravity, recently defined by Xu et al. [[ ] gravity, Eur. Phys. J. C 79 (2019) 708]. The nonlinear model [ ], where [ ] and [ ] are constants, is taken into account. The equation of state of perfect fluid is assumed and 31 points of Hubble data are used to constrain the value of model parameter. To explore the evolution of the universe, the numerical solutions of cosmological implications, such as Hubble parameter, deceleration parameter, apparent magnitude and luminosity distance, are determined and the energy conditions are examined. The theoretical results of Hubble parameter are compared with [ ]CDM model. Further, 57 Supernova data (42 from Supernova cosmology project and 15 from Calán/Tolono supernova survey) are also used to have consistent results of apparent magnitude and luminosity distance.