This paper identifies mechanical vibrations occurring in the operating environment of hydraulic systems used in marine engineering. Particular attention was paid to the influence of periodic vibrations on changes in the amplitude-frequency spectrum in a marine hydraulic system. For the case of analysing the effect of vibration on changes in the pressure pulsation spectrum with a proportional directional valve, a modified mathematical model was used. Experimental results were presented and compared with the results obtained from the mathematical model. A way of limiting the transmission of vibrations to the directional control valve body was proposed.

Noise pollution from the streets is a critical problem for those living or working near them. Although the traffic noise problem is not a new research topic, it is usually limited to providing average values. This paper aims to determine variations in the instantaneous noise level and its influencing factors using the experimental noise level and theoretical traffic flow using a discrete traffic flow model. The research results suggested that the noise level could be changed by properly managing traffic flow with existing traffic lights without changing the infrastructure. The results of this research may be useful for city transport traffic management institutions.

Considering the characteristics of urban planning that are becoming increasingly demanding, and the trend that urban zones should meet users’ needs based on the principle of everything in one place, this paper evaluates the potentials of urban zones in Novi Sad. An expert analysis defined 25 criteria related to urban, traffic, architectural, environmental and sociological aspects to assess the current potentials of urban zones in a sustainable manner. Based on these criteria, 10 urban zones were evaluated using a multi-structure fuzzy MCDM model, including: the Fuzzy FUCOM, IMF SWARA and Fuzzy OPARA methods, and the Fuzzy Heronian Mean and Fuzzy Bonferroni operators. Fuzzy FUCOM was applied to determine the importance of the main groups of criteria, while IMF SWARA was used to determine the importance of sub-criteria, with the final weights obtained using the Fuzzy Heronian Mean operator. The Fuzzy OPARA method was implemented to determine the rankings of urban zones based on the potentials they offer. This model represents an innovation, as it is being presented for the first time in the literature. The final values of the urban zones show that Liman and the Center are the two urban zones with the greatest potential, which was confirmed through extensive verification analysis. Such modeling can provide support in the sense that the management of the city can obtain information about the shortcomings and potentials of the location, which allows for the definition of a more specific planning and development policy, based on the previously verified state.

Global natural gas resources are growing and are increasingly geographically diverse. A Floating Storage and Regasification Unit (FSRU) is one of the most commonly used vessel types in the global ship fleet due to the possibility of storage, reloading to another ship, and regasifying it for re-injection into the natural gas grid. It is important to control system parameters for reliable technological processes such as tank hydrostatic pressure, vapor pressure, LNG density, LNG temperature, and phase changes between liquid and gas states. Additionally, pressure monitoring is important to control during transit in port and bunkering to prevent the pressure in the tanks from exceeding the tank design pressure. In this research study, a comprehensive hydrodynamic model for an LNG storage tank in a real-life regasification terminal (Floating Storage and Regasification Unit, LNG Terminal of Klaipeda City, Lithuania), operating in transportation mode to the regasification unit, was created. For this research, LNG is investigated as a compressible liquid and the speed of sound in LNG is evaluated. A complex mathematical model of the system allows the analysis of high-speed hydrodynamic and dynamic processes at cryogenic temperature (110 K) and evaluates the geometric parameters (tank geometry, electric motors and pumps, pipe geometric parameters, and roughness of internal surfaces) and the characteristics of pumps and electric motors. The complex mathematical model of the system was implemented using Fortran programing language and MATLAB R28a. It determined the parameters (pressure, velocity, liquid level of LNG in the tanks, electric motor angular velocity, torques, hydraulic energy losses, etc.) of the system during its start-up mode (until 5 s). It was found that hydraulic energy losses in all pipes contain 1.7% of the whole system power (the total power of the electric motors is 3132 kW). In case of increasing energy costs, this model could be used to control energy losses during the operation of the FSRU in various technological modes.

This paper presents both an example of the innovation prototype risk assessment and the universal way of conduct in assessing such solutions. For this purpose, the authors proposed a prototype risk assessment method based on the assumptions of the SWOT and TOWS analysis and the multi-criteria technical innovation risk assessment method. In the assumptions of the developed method, an account was taken of the conclusions resulting from the prospect theory. A symptom of this action was, e.g., a characterization of the team of experts (working on the prototype) in terms of their individual personality traits and mind (which has not been used so far in practical methods of assessing risk). As a result of the conducted assessment (for an innovative hydraulic cylinder prototype), the innovation prototype risk was determined as low, which was presented both on the map of domination and the map of risk assessment for this prototype. The procedure presented in the paper was planned so as to ensure that, after the prototype moves to the commercialization phase, it will be possible, on the basis of the already made calculations, to apply the full risk assessment dedicated for technical innovations with ease. This gives it a universal nature.

The reduction of the weight of high-pressure components and systems (including hydraulic) is especially important in aircraft or mobile machinery. An interesting trend that began in the first half of the 20th century in the aviation industry is the weight reduction of structures by using components made of composite materials in place of those made of conventional materials. This trend is not only not diminishing, but is actually increasing year by year. This paper investigates the effect of modifying the design of the sickle insert on the volumetric efficiency of the pump. Moreover, this work presents the replacement of the sickle insert of an internal gear pump made of bronze with plastic materials, reducing its weight by 80%. To ensure similar performance, its design was modified, increasing the pump’s efficiency while additionally reducing its weight. This material substitution allows the reduction of weight, but it can adversely affect the performance of the hydraulic component, this also applies to the displacement pumps. For this reason, the design had to be changed to obtain similar operational parameters after changing the material.