An (s, S) inventory system with service facilities has been investigated in this study. Demands arrive as a Poisson process with parameter λ (>0) to an infinite capacity pool at any given time t. When the inventory is greater than the buffer size a customer will transfer to the buffer with rate ϕ. The service time is considered to be distributed exponentially with the parameter μ. The level of inventory is likewise presumed to be S at first. When the inventory level reaches s as a result of service, or due to perishability of the inventory, a replenishment order is taken place. With the parameter β, the lead time is distributed exponentially. The impact of various factors and cost rates have been examined in an infinite pool capacity system using sensitivity analysis.

The world's big economies are roiled and going under a devastating threat amid the impact of the COVID-19 pandemic. No country will be safe as this virus will eventually outbreak everywhere, regardless of how countries prepare to avoid it. The economic ramification as well as the stock market crisis will be uncertain due to the extended suspension of economic activities in almost every country. No wonder, the clattered stock markets of Bangladesh which have already got the adjective of “the worst stock market in the world” because of inefficient and irrational fluctuations in previous years will experience a colossal crisis due to the pandemic. The article provides an investigation on comparable analysis of the impact on stock markets of Bangladesh, Dhaka stock exchange, and Chittagong stock exchange, before and after the pandemic situation with current market data. We also examine the potential consequence of policy interventions to the market and the investors during a pandemic.

The performance of a primary cell highly depends on the coulombic efficiency of that cell. Being a primary cell, Bryophyllum pinnatum leaf generated BPL cell, where electrodes- pair of zinc and copper dipped in the filtered leaf juice, a good efficiency is required. In this paper, we have tried to show the approximate coulombic efficiency of a unit BPL cell on a certain condition.

The leaf of Bryophyllumpinnatum plant contains some organic acids. A technique has been developed to extract electrical energy from this leaf. A cell fueled by Bryophyllum pinnatum is called BPL cell. Our study showed that, this kind of cell is capable for LED bulb lightning, tuning radios and even charging mobiles. So, from this BPL cell, people at the off-grid region can get some electricity and can get benefitted a lot. In this paper, we shall try to show our work on the self-discharge characteristic of the BPL test cell in a new way.