Efficiency of circular economies is one of the most important areas of the improvement of economic growth in a circular way, that is, improving worldwide GDP. The issue of circular economies, namely their efficiency, is a current topic of evidence of many literary sources in the literature. This issue is solved in the conditions of the Czech Republic, Poland, Hungary and Slovakia. The goal of the study is to compare the circular efficiency within the Visegrád Group and efficiency of Visegrád Group countries to the European Union 28 average. Data envelopment analysis slack-based models are implemented to evaluate the output efficiencies of the selected subjects. Truncated regression is used to measure the impact of selected indicators on circular efficiency. The Visegrád Group countries are not among the most advanced in terms of recycling and the use of the circular economy, which was confirmed by this research. However, developments suggest significant improvements. The significance of this research lies in several benefits. One of the benefits is the perception of regional differences and the setting of EU cluster policies at the regional level. The idea of changing inputs is very significant since the outputs are oriented to the recycling rates of materials and waste. This research has shown that a higher level of GDP does not necessarily mean a higher level of efficiency of the circular economy.

Photovoltaic power plants are considered to be environmentally friendly solutions to the production of electricity. Solar energy conversion does not release toxic compounds into the environment. However, the construction of solar power plant components (photovoltaic modules, sup-porting structure, inverter station, electrical installation) is extremely consumptive of energy and materials. Massive volumes of minerals, fossil fuels, and electricity are consumed during the manufacturing process. Efficient management of energy and environmental resources seems to be critical for national policy. It is crucial to admit that the post-consumer management of the components of a photovoltaic power plant is connected with a certain quantity of energy and matter and a negative impact on the natural environment. A life cycle assessment was carried out on a real 2 MW photovoltaic power plant located in the northern part of Poland. The analysis was carried out applying the ReCiPe 2016 model and the Life Cycle Assessment (LCA) approach. The impact of the examined renewable energy system was evaluated using 22 impact categories and 3 emission areas (air, water, soil). Life Cycle Assessment analysis was carried out for 2 post-consumer development scenarios (landfill and recycling). The examination of the collected results reveals that photovoltaic modules are the element causing the most negative environmental repercussions connected to the release of dangerous compounds into the atmosphere. Post-consumer development in the form of recycling would provide major environmental benefits and reduce detrimental environmental consequences across the whole life cycle of the photovoltaic power plant. The obtained research results enabled the formulation of pro-environmental recommendations aimed at the long-term development of the life cycle of solar power plants.

Reverse logistics concept in the global scale has been already existing for about two decades. However, in Poland it is quite new one, not very popular and widespread. During the constant economy development and increasing market competition Polish enterprises are forced to seek for some modern solutions to improve their business activity and reverse logistics might be the answer for these aspirations for better performance. But the decision about reverse logistics processes implementation into practice of the company is not the easy one. During this kind of investment and after it, while maintenance, there might occur many barriers and obstacles hard to force and effective in preventing the good reverse logistics.

Diversity management is a marginal strategic issue in transportation and logistics companies. The industry falls short of taking full advantage of the significant benefits that gender and cultural diversity can offer. The business reality of logistics sector companies proves that there are enterprises that announce and maintain proper practices leading to diversity. One of such companies is Deutsche Post DHL (DP-DHL) which manages diversity at advanced level. In the light of the above, the aim of the paper is to point out the importance of diversity management in the context of CSR and responsible management of human resources. The paper also aims at presenting the practices of diversity management (DM) of DP-DHL

The aim of this study is to investigate changes in the wind power plant energy production parameters under the conditions of sudden wind changes and voltage drop. To achieve these goals, a simulation of operation of wind power plants was performed. Twelve wind turbines with variable rotational speed equipped with a Fuhrländer FL 2500/104 asynchronous double-fed induction generator (DFIG) were used, each with an installed capacity of 2.5 MW. A general scheme of a wind power plant has been developed using a modular-trunk power distribution scheme. The system consists of wind power modules and a central substation, which allows total power to be supplied to the power system at a voltage of 35 kV. The central substation uses two high voltage switchgears. Four modules were used, each of them consisting of three wind turbines, with a power of 7.5 MW. The simulation of the wind turbines was performed in the MATLAB^® Simulink^® software environment. The mode of response of the turbines to a change in wind speed, a voltage drop in the 35 kV voltage system, and a one-phase short circuit to the ground in the system of 10.5 kV voltage was explored. The results show that a sudden voltage drop and the appearance of short circuits influence the wind power plant (WPP) operation in a different way independent of regulation mode. The power generation from WPP will be limited when voltage drop occurred for both AC and Voltage regulation mode and during short circuits while WPP is set on AC regulation mode.

Artificial intelligence (AI) is fundamentally transforming human resource management (HRM) by automating processes, improving efficiency, and reshaping organizational dynamics. This study examines the multifaceted impacts of AI on HRM, focusing on its potential to enhance employee productivity and streamline operations. While AI introduces significant opportunities, including better candidate-job matching and predictive workforce analytics, it also presents challenges such as ethical concerns, potential biases, and the displacement of certain job roles. The analysis is grounded in current scientific research and practical applications, highlighting the dual role of AI as both an enabler of innovation and a source of ethical and operational dilemmas. By addressing these complexities, the study aims to provide a comprehensive perspective on how AI can be effectively integrated into HRM practices to achieve sustainable organizational growth.