Publications

The effect of expert decision-making style on the design process of innovative toothed gear pumps – a case study

urpose: The main goal of this research was to verify the adopted research thesis, i.e.: design engineers have a unique and uniform procedure applied in the decision-making process, which affects their ability to create new solutions. Design/methodology/approach: The paper's authors assumed that experts – design engineers have specific personality traits that determine their decision-making style. In order to verify this assumption was maked: analysis of selected personality traits of experts, assessment of individual decision-making styles, detailed analysis of the decision-making process, within which the design of innovative toothed gear pumps is carried out, decision-making analysis related to the development of a new innovative solution, analysis of the impact of personality traits and decision-making style on the process of designing innovative gear pumps. The study used tools such as the Decision-Making Styles Inventory – KSPD, Expert Behavior Questionnaire – EBQ, Expert Mind Questionnaire – EMQ, and SCAMPER technique. Findings: The analysis of the obtained results allows us to assume that the selected team of experts allows for creating and generating new solutions while maintaining the desired level of caution in the scope of risk analyses. In the case of forming project teams, the use of tools that support their selection, such as EBQ and EMQ, can be considered an advantage. Such analyses can be supplemented by the application of the KSPD. As a result of the broad analyses of the decision-maker's personality, it is possible to characterize the experts in terms of their predispositions to create new innovative solutions. Moreover, a distinctly rational approach to decision-making constitutes a common feature for designer engineers, which is supported by intuition at the same time. However, the research presented in the work shows that expert design engineers utilize intuition in their work and then make decisions based on facts and data. This style is strongly correlated with the areas of expert behaviors concerning cognitive motivation and open-mindedness. Originality/value: Identify unique personality traits for design engineers and define their impact on the effectiveness of their decisions. Keywords: decision-making process, design engineers, personality traits, intuition, rational approach. Category of the paper: Research paper, case study.

Analiza porównawcza analitycznych i numerycznych metod wyznaczania wytężenia kół stosowanych w pompach zębatych

Comparative Analysis of Energy Efficiency and Position Stability of Sub-250 g Quadcopter and Bicopter with Similar Mass Under Varying Conditions

This paper investigates the energy efficiency and positional stability of two types of ultralight unmanned aerial vehicles (UAVs)—bicopter and quadcopter—both with mass below 250 g, under varying flight conditions. The study is motivated by increasing interest in low-weight drones due to their regulatory flexibility and application potential in constrained environments. A comparative methodology was adopted, involving the construction of both UAV types using identical components where possible, including motors, sensors, and power supply, differing only in propulsion configuration. Experimental tests were conducted in wind-free and wind-induced environments to assess power consumption and stability. The data were collected through onboard blackbox logging, and positional deviation was tracked via video analysis. Results show that while the quadcopter consistently demonstrated lower energy consumption (by 6–22%) and higher positional stability, the bicopter offered advantages in simplicity of frame design and reduced component count. However, the bicopter required extensive manual tuning of PID parameters due to the inherent instability introduced by servo-based control. The findings highlight the potential of bicopters in constrained applications, though they emphasize the need for precise control strategies and high-performance servos. The study fills a gap in empirical analysis of energy consumption in lightweight bicopter UAVs.

The influence of hydraulic hose length on dynamic pressure waveforms including wave phenomena

Optimizing the Break-in Process of High-Pressure Gear Pumps

Badania mocy cieplnej w pompie zębatej 3PZ4

Identification of Disturbance Signals in Hydraulic Systems in Terms of Their Reliability

Vibroacoustic Diagnostics of Rolling Bearings - Test Rig for Research Dataset Acquisition and Didactic Applications

Opracowanie metody wyznaczenia zastępczych charakterystyk sprawnościowych dla pomp wyporowych

Durability tests of prototype gear pumps with reduced flow ripple

This article presents the results of a durability test of a prototype low-pulsation pump. Hydraulic measurements conducted during the test enabled visualisation of the behaviour of the unit in working conditions. The test was conducted according to a strict factory standard, which states that pump performance parameters cannot decrease by more than 8% during durability testing. The material presented in this publication is the result of a study within the project entitled The development of innovative gear pumps with a reduced level of acoustic emission. The solution developed as part of the project has been successfully implemented for a series of gear pumps consisting of twenty-two units. Among other awards, the product won the Gold Medal at the 10th International Fair of Pneumatics, Hydraulics, Drives and Controls, Kielce 2017.

Badania trwałościowe niskopulsacyjnej pompy zębatej

Modeling Transient Pipe Flow in Plastic Pipes with Modified Discrete Bubble Cavitation Model

Most of today’s water supply systems are based on plastic pipes. They are characterized by the retarded strain (RS) that takes place in the walls of these pipes. The occurrence of RS increases energy losses and leads to a different form of the basic equations describing the transient pipe flow. In this paper, the RS is calculated with the use of convolution integral of the local derivative of pressure and creep function that describes the viscoelastic behavior of the pipe-wall material. The main equations of a discrete bubble cavity model (DBCM) are based on a momentum equation of two-phase vaporous cavitating flow and continuity equations written initially separately for the gas and liquid phase. In transient flows, another important source of pressure damping is skin friction. Accordingly, the wall shear stress model also required necessary modifications. The final partial derivative set of equations was solved with the use of the method of characteristics (MOC), which transforms the original set of partial differential equations (PDE) into a set of ordinary differential equations (ODE). The developed numerical solutions along with the appropriate boundary conditions formed a basis to write a computer program that was used in comparison analysis. The comparisons between computed and measured results showed that the novel modified DBCM predicts pressure and velocity waveforms including cavitation and retarded strain effects with an acceptable accuracy. It was noticed that the influence of unsteady friction on damping of pressure waves was much smaller than the influence of retarded strain.

LEAKAGE LOCATION IN HIGH PRESSURE EXTERNAL GEAR PUMP

Unevenness of Hydraulic Cylinder Speed and Pressure Pulsation Caused by External Mechanical Vibrations

A novel design of a low-pressure composite vessel with inspection opening – design, manufacturing and testing

Composite structures, especially pressure vessels, pipelines, and additional components such as tees, reductions, or inspection openings are more and more willingly used in the chemical industry. In this research, a novel design of a low-pressure composite vessel with an inspection opening is presented. The vessels are unsymmetrical considering the domes. On one side the opening is considerably bigger, around half of the cylindrical diameter of the vessel. This design requires a new approach to manufacturing such structures. In this study, a two-step analysis was performed. Firstly, small-size pressure vessels (S) were manufactured and the design of dome reinforcement was validated. Then, the final design of vessel (M) was produced, with a volume of around 700 litres. The vessels were initially calculated for 21 bars of burst pressure. During burst pressure tests, the strains were measured with optical fibres (FBG) and strain gauges. Additionally, the acoustic emission was utilized to predict the damage modes and locations. Finally, a microscopic evaluation of the specific parts of the vessels was performed. Conclusions were drawn, that the proposed novel design of dome reinforcement around the inspection opening fulfilled the strength and stiffness requirements.

Experimental Evaluation of Energy Consumption and Acoustic Emissions in Sub-250 g Quadcopters with Added Tubular Propeller Enclosures

This paper investigates the impact of tubed propeller design on the energy efficiency and acoustic emissions of sub-250 g quadcopters. This study was motivated by the growing popularity of ultralight UAVs and the lack of experimental data addressing the trade-offs between noise, efficiency, and mass. Ten drone configurations with varying tube geometries and tip clearances were constructed using 3D-printed PLA+ frames and identical propulsion components. Experimental tests were conducted in a reverberation room to measure sound pressure levels and onboard energy consumption during hover. The results show that tubed configurations are 3–6.5 dB louder than untubed ones, with a noticeable shift toward higher frequencies. While tubes increased total power demand by 18–37% compared to the lightest design, they also reduced it by 3–17% relative to untubed drones of the same mass. The findings demonstrate that tubing improves aerodynamic efficiency only under same mass constraints and is most beneficial when mechanical protection is prioritized over noise and endurance.

A Case Study of Open- and Closed-Loop Control of Hydrostatic Transmission with Proportional Valve Start-Up Process

This paper concerns the start-up process of a hydrostatic transmission with a fixed displacement pump, with particular emphasis on dynamic surplus pressure. A numerically controlled transmission using a proportional directional valve was analysed by simulation and experimental verification. The transmission is controlled by the throttle method, and the variable resistance is the throttling gap of the proportional spool valve. A mathematical description of the gear start-up process was obtained using a lumped-parameters model based on ordinary differential equations. The proportional spool valve was described using a modified model, which significantly improved the performance of the model in the closed-loop control process. After assuming the initial conditions and parameterization of the equation coefficients, a simulation of the transition start-up was performed in the MATLAB–Simulink environment. Simulations and experimental studies were carried out for control signals of various shapes and for various feedback from the hydraulic system. The pressure at the pump discharge port and the inlet port of the hydraulic motor, as well as the rotational speed of the hydraulic motor, were analysed in detail as functions of time. In the experimental verification, complete measuring lines for pressure, speed of the hydraulic motor, flow rate, and temperature of the working liquid were used.

Development Trends in Compensation Methods for External Gear Pumps