The search for opportunities to save and use energy efficiently should primarily focus on sectors of the economy with the highest energy consumption. One such sector is construction. Buildings built in Poland in different periods according to the introduced and successively tightened thermal protection requirements have different energy characteristics, which differ from contemporary standards and future expectations in this respect. This article presents guidelines for the energy transformation of building resources towards climate neutrality and the condition of these resources in Poland to an extent relevant for estimating the energy savings potential as a result of their thermal modernization. The economic aspect relating to the implementation of the energy policy is also presented. Over the last twenty years, there has been a nearly 37% increase in final energy consumption and a close to 34% decrease in final energy intensity of gross domestic product (GDP) recorded in Poland, which proves that energy efficiency is growing virtually without increasing energy demand. Significant potential for rationalizing energy consumption is found, as well as the need to incur high costs relating to the construction sector transformation. The problem is the lack of databases on the technical condition, age, and energy performance of various groups of buildings, which means it is difficult to determine the thermal modernization needs and the achievable effects of energy savings for the entire building stock. Some inconveniences relating to the implementation of zero-emission guidelines are also pointed out due to the fact that the Polish energy system is largely based on fossil fuels.

This paper substantiates the method of polarization selection of navigation objects located in the zone of atmospheric formations (i.e., precipitation of different intensity and phase state), based on polarization differences in the parameters of their echo signals in a partially polarized electromagnetic wave arriving at the input of the all-polarized antenna of the ship radar polarization complex (SRPC). The partially polarized wave is represented as consisting of two polarized streams with polarization degrees m1 and m2 corresponding to the echo signals of the navigation object and atmospheric formation. The property of the partially polarized electromagnetic wave reflected from a complex object (i.e., navigation object located in the zone of atmospheric formation) is represented by real energy polarization Stokes parameters having intensity dimension. The scattering ability of the complex object is represented by the Mueller scattering matrix, the elements of which are measured by SRPC when it is sequentially irradiated with electromagnetic waves of four fixed polarizations. Polarization selection of navigation objects located in the zone of atmospheric formations uses the difference of polarization degrees of echo signals of the navigation object and atmospheric formation. The process of selection of the navigation object echo signal from the echo signal of the complex object and its observation on the screen of the SRPC indicator or computer display is based on the relationship between the degree of polarization of the electromagnetic wave and the polarization parameters of the navigation object echo signal and the atmospheric formation. The aim of this research is to develop polarization criteria of optimality of radar parameters of echo signals of partially polarized electromagnetic waves, represented by polarization degrees m1 and m2 corresponding to the navigational object and atmospheric formation observed by SRPC. As a result of the performed research, the problem of polarization selection of navigation objects located in the zone of atmospheric formations along the ship’s trajectory according to the values of the polarization degree of the navigation object echo signal is solved.

Marinas are of key importance in the development of sustainable marine tourism, whereas requirements posed by certification organizations can have a motivating effect and contribute to the implementation of environmentally and socially friendly solutions. The aim of this study is to analyze two world-leading marina categorization systems: the Gold Anchor Scheme and the IMCI Blue Star Marina Certification System. A special focus is made on the criteria relating to sustainable development, such as requirements concerning services, equipment, and management, posed to marinas by the accreditation bodies. The following research question has been defined: Do certification and categorization contribute to the development of sustainable sailing tourism? The results of the conducted analyses show that part of the requirements set by the accreditation organizations running two of the most popular marina categorization schemes worldwide relate to the achievement of sustainable development goals. The requirements motivate the management at marinas applying for a category to implement solutions that are friendly to the environment and society, and contribute to the growth of local economies. The research results indicate that the categorization of marinas is not only of some marketing value but is also a useful tool in the development of sustainable marine tourism.

District heating networks are key components of efficient heat supply systems for municipal and industrial consumers. The purpose of the research presented in this article was to analyze the thermo-hydraulic parameters of the operation of a transmission main in a district heating network to improve the heat transfer efficiency. Based on a literature review of existing studies, the basic issues of the heat supply process were discussed, and selected methods and tools for simulating district heating networks were characterized. A detailed mathematical description of the phenomena occurring during heat transport in a district heating network pipeline was also presented. Then, analytical calculations and simulations were carried out for the selected district heating system using Termis software. Operational parameters collected in the actual district heating system were used as output data for analytical modeling. Pressure drops, power losses, and heat transfer efficiencies in the main buses at different outdoor temperatures during the heating season were determined. Selected results of the study were included, and possibilities for improving the efficiency of heat transfer in the studied district heating network were indicated.

The COVID-19 pandemic is undoubtedly a global crisis that has forced the world economy to a standstill. Subsequent lockdowns have caused downtime in all industries and all transportation sectors. The removal of the restrictions has made it possible to begin a slow return to pre-pandemic conditions, but research indicates that this will be a long process. Therefore, an indication of the development trends of passenger maritime transport in Poland, considering the impact of the COVID-19 pandemic, is the purpose of the article. Two specific objectives are identified: (1) To visualize the impact of the COVID-19 pandemic on passenger maritime transport in Poland; (2) To make long-term forecasts of passenger maritime traffic in Poland. The analyses showed that the COVID-19 pandemic had a very negative impact on passenger streams. It may take several more years to recover from the pre-pandemic state.

This work is devoted to a computational investigation of the position and volume of the cavitation cloud in a cavitation tunnel. The position of the cavitation cloud and its volume in the cavitation tunnel, determined by numerical analysis with respect to the inlet velocity, allows for the determination of the lower or higher intensity of cavitation erosion within the tunnel of the sample material. A numerical analysis is carried out on a model of a typical cavitation tunnel used to investigate the resistance of structural materials to cavitation erosion. The tunnel under study consists of barricade (upper) and counter-barricade (lower) systems. The numerical analysis is carried out with the following five different values of the velocity in the tunnel inlet: 6 m/s, 9 m/s, 12 m/s, 15 m/s, and 18 m/s in the commercial CFD software – Ansys Fluent 2019 R3. The Schnerr and Sauer cavitation model and shear stress transport (SST) viscous model k-omega are used. The paper analyzes the distribution of velocity, pressure, and volume of the cavitation cloud. On the basis of the performed numerical analyses, the optimal velocity at the inlet to the tunnel of 15 m/s is determined, for which the volume of the cavitation cloud is the largest and the phenomenon of cavitation is the most intense. The determination of the position and maximum volume of the cavitation cloud relative to the inlet velocity to the tunnel will, in future, allow us to shorten the resistance tests for cavitation erosion of different materials under real fluid flow conditions.

The main interest in introducing maritime autonomous surface ships (MASS) is centered on communication, autonomous navigation, and collision avoidance systems. This paper presents a more comprehensive approach, accounting for selected issues relating to navigation safety, ship operation, maritime rescue, and decision support systems for the MASS remote managing operator. The technical solutions for improving the safety of MASS operation are described, and the decision support system (DSS) for the MASS operator, based on the stochastic model of the process describing the safety of MASS operation, is proposed. The presented analysis can be used to build a computer program and an integrated decision support system that increases the safety and reliability of the MASS operator’s decision-making process.

The restrictions on carbon dioxide emissions introduced by the European Union encourage experimental work on new-generation materials containing smaller amounts of clinker. At present, silica fly ashes from the combustion of hard coal are widely used in the technology of cement and concrete in Europe and Poland. This research aims to assess the physical and chemical properties of fly ashes from the thermal treatment of sewage sludge for use in concrete technology in relation to applicable standards and determine their impact on the natural environment. The established concentrations of heavy metals are below the maximum values required when discharging sewage into the ground or waters and also meet the necessary leaching limits when inert waste is allowed to be landfilled and on substances particularly harmful to the aquatic environment. On this basis, it was found that the migration of heavy metals from concrete with the addition of ashes to the water environment is insignificant and should not be a major problem. In addition, the tests showed that the activity index did not exceed the limit value.

Investigations into driver’s behavior are a very important and frequently addressed topic by researchers. They allow us to understand drivers better and characterize their behavior. However, this can be difficult due to the many factors that affect the driver while driving. Therefore, many efforts are being made to improve the safety of both drivers and other road users. In this study, in order to better understand and describe the driver’s driving behavior, the results of a pilot study conducted under real traffic conditions are presented. The test route includes different road types and is characterized by varying traffic conditions. Modifications in simple vehicle movement parameters are analyzed in relation to changes in the way drivers drive test routes.

The main objective of this article is to indicate whether returns treated as a resource impacts uncertainty in supply chain management. Through an empirical study using the CATI method, the significance of factors that improve the efficiency of return flow in supply chains and the significance of types of uncertainty in supply chain management are presented. The analysis, performed using Pearson’s linear correlation coefficient, indicates relationships and dependencies between variables, such as the drivers of the flow of returns in the supply chain and types of uncertainty. As a consequence of the research and an analysis of its results, it is possible to demonstrate the complexity of the problem, but above all, it is possible to indicate which of the above-mentioned factors affect the reduction of the impact of uncertainty on the supply chain. The presented approach is one of the voices in the ongoing scientific discussion on the management of supply chains under conditions of uncertainty.

The operation of offshore structures at sea requires the implementation of advanced systems for their permanent monitoring. There is a set of novel technologies that could be implemented to deliver a higher level of effective and safe operation of these systems. A possible novel solution may be the application of a new maritime unmanned (USV) surface and underwater vehicles/platforms (AUV). Application of such vehicles/platforms may increase the level of operability and safety of the offshore structures and installations. Practical use of these platforms requires the application of advanced forms of different technologies to platform structures, materials, strength of structures, applied propulsion systems, energy supply sources, dynamics of platforms, control, and communication systems. The new control and communication systems may require an application of AI (artificial intelligence) technology to obtain more advanced offshore monitoring systems. The application of the USV/AUV platforms for monitoring offshore structures may provide an increase in the functionality, performance, and safety levels of those structures in operation. This paper presents a concept for an offshore monitoring system based on the application of the USV/AUV platforms. The complexity of the research is shown by presenting the performance-oriented risk-based method. The basic information on the platforms is given. The main drivers that determine the functionality, performance, and safety of the USV/AUV platforms are introduced. A brief description of the primary operational characteristics of the platforms is presented. An example of a simple operational procedure (scenario) during the monitoring of an offshore structure is described. In the final part of this paper, conclusions are given.