Logistic Wavelets and Their Application to Model the Spread of COVID-19 Pandemic

Ensuring the business continuity of production companies in conditions of COVID-19 pandemic in Poland - Applied measures analysis

The purpose of the paper is to present the results of the study of solutions implemented in Polish manufacturing companies to ensure their business continuity under COVID-19 pandemic conditions. A questionnaire survey was conducted using the mixed-model CAWI/CATI (Computer Assisted Web Interview/Computer Assisted Telephone Interview) on a representative group of 600 manufacturing companies in Poland. The research was conducted in March 2021, more than a year after the first lockdown. The study included cases of companies in most industries and companies of different sizes. The subject of the survey was to identify legal, technical, and organisational protection measures implemented in manufacturing enterprises in response to the COVID-19 pandemic in manufacturing companies in Poland. The COVID-19 pandemic has forced companies to look for solutions to work safely. Some of the identified work and production organisation solutions are innovative and can serve as models of good practice for other companies. They can also be the basis for learning lessons and preparing for future critical incidents. It is a great economic and social importance to ensure the continuity of the activities of manufacturing enterprises during the pandemic.

Reconstruction of Epidemiological Data in Hungary Using Stochastic Model Predictive Control

In this paper, we propose a model-based method for the reconstruction of not directly measured epidemiological data. To solve this task, we developed a generic optimization-based approach to compute unknown time-dependent quantities (such as states, inputs, and parameters) of discrete-time stochastic nonlinear models using a sequence of output measurements. The problem was reformulated as a stochastic nonlinear model predictive control computation, where the unknown inputs and parameters were searched as functions of the uncertain states, such that the model output followed the observations. The unknown data were approximated by Gaussian distributions. The predictive control problem was solved over a relatively long time window in three steps. First, we approximated the expected trajectories of the unknown quantities through a nonlinear deterministic problem. In the next step, we fixed the expected trajectories and computed the corresponding variances using closed-form expressions. Finally, the obtained mean and variance values were used as an initial guess to solve the stochastic problem. To reduce the estimated uncertainty of the computed states, a closed-loop input policy was considered during the optimization, where the state-dependent gain values were determined heuristically. The applicability of the approach is illustrated through the estimation of the epidemiological data of the COVID-19 pandemic in Hungary. To describe the epidemic spread, we used a slightly modified version of a previously published and validated compartmental model, in which the vaccination process was taken into account. The mean and the variance of the unknown data (e.g., the number of susceptible, infected, or recovered people) were estimated using only the daily number of hospitalized patients. The problem was reformulated as a finite-horizon predictive control problem, where the unknown time-dependent parameter, the daily transmission rate of the disease, was computed such that the expected value of the computed number of hospitalized patients fit the truly observed data as much as possible.