Cavitation Erosion of Protective Coating Based on Cordierite Filler and Epoxy Matrix

The goal of this study is to investigate the surface morphology changes induced by the cavitation erosion of a coating based on cordierite with an epoxy matrix for an aluminum substrate. The literature review shows a certain lack of knowledge regarding the coating’s resistance to wearing induced by water flow, which is a highly important property of the material immersed in or in contact with water streams. The main idea behind the investigation is that such a protective coating will also improve the cavitation erosion resistance of metal substrates. The protective coatings were based on cordierite filler (88 wt.%) and epoxy resin (7 wt.%). The filler, made of a mixture of kaolin, alumina, and talc, is obtained by a sintering procedure that took place at 1350 ◦C. X-ray diffraction analysis and scanning electron microscopy were employed in the characterization of the produced filler. The adherence of the obtained epoxy-based protective coating and resistance to water flow were tested by the ultrasonic vibration method (i.e., cavitation erosion testing). Scanning electron microscopy was used for analysis of the coating’s morphology upon cavitation erosion. Based on the value of the cavitation erosion rate and the analyzed final surface damage, it was assessed that the investigated protective coating is resistant to cavitation erosion

The phosphorus negotiation game (P‑Game): frst evaluation of a serious game to support science‑policy decision making played in more than 20 countries worldwide

Environmental negotiations are complex, and conveying the interaction between science and policy in traditional teaching methods is challenging. To address this issue, innovative educational approaches like serious gaming and role-playing games have emerged. These methods allow students to actively explore the roles of diferent stakeholders in environmental decision-making and weigh for instance between sometimes conficting UN Sustainable Development Goals or other dilemmas. In this work the phosphorus negotiation game (P-Game) is for the frst time introduced. We present the initial quantitative and qualitative fndings derived from engaging 788 students at various academic levels (Bachelor, Master, PhD, and Postdoc) across three continents and spanning 22 diferent countries. Quantitative results indicate that female participants and MSc students beneftted the most signifcantly from the P-Game, with their self-reported knowledge about phosphorus science and negotiation science/practice increasing by 71–93% (overall), 86–100% (females), and 73–106% (MSc students in general). Qualitative fndings reveal that the P-Game can be smoothly conducted with students from diverse educational and cultural backgrounds. Moreover, students highly value their participation in the P-Game, which can be completed in just 2–3 h. This game not only encourages active engagement among participants but also provides valuable insights into the complex environmental issues associated with global phosphorus production. We strongly believe that the underlying methodology described here could also be used for other topics

Evaluation of hull girder ultimate strength for dry cargo inland vessels

Ultimate strength of sea-going ships is investigated in literature and addressed in the rules and regulations of classification societies, where detailed contemporary methods are defined. However, no systematic assessments or developed regulations for evaluating the ultimate strength of inland vessels have been introduced. This is concerning, considering that around 15,000 inland vessels navigate in Europe alone. These vessels are generally prone to longitudinal strength issues as they face specific design, operational and regulatory challenges, such as a large length-to-height ratio, shallow draught navigation, frequent grounding and overloading accidents, an older fleet and fewer regulatory requirements compared to sea-going ships. Therefore, this study presents a pioneering evaluation: it assesses ultimate strength of ten inland vessels, addressing this significant gap in literature. Five methods are employed for the calculation of ultimate strength: IACS defined progressive collapse analysis (PCA), three modified PCA methods according to different formulations for buckling of stiffeners, and a nonlinear finite element method. Moreover, maximum total bending moments are calculated in order to examine the margin between ultimate and service loads. Selected inland vessels are found to be particularly vulnerable to hull girder collapse, with some of them having extremely low or no margin with respect to hull girder collapse, largely due to the buckling of structural elements acting as a consequence of the selection of unique, dispersed and specific structural features. The research specifically emphasizes that vessels with longitudinal framing achieve higher ultimate strengths, offering greater structural safety against hull girder collapse

Estimation of residual operability and energy efficiency optimization of oil purification column

This paper examines the process of oil distillation in upstream oil and gas facilities, along with the main equipment involved. A vertical column, a key component of the stabilization system that has been in operation for almost 20 years, was tested. The column was temporarily taken out of service to conduct a detailed, non-destructive inspection. Due to its long-term operation, aging, and exposure to corrosive environments—especially oil corrosion—it represents high-risk equipment with potential environmental and financial consequences in the event of failure. This study aims to determine the optimal operating mode to improve output product quality. Ultrasonic thickness testing (UTT) was performed, revealing wall thinning in critical areas. The maximum calculated corrosion rate was 0.0722 mm/year, and the remaining service life was estimated at 26 years. Based on the risk-based inspection (RBI) analysis, the column falls into the high-risk category, emphasizing the importance of optimized inspection planning. An RBI analysis was conducted using API 581 methodology, classifying the column as high-risk equipment with potential financial consequences exceeding €2.7 million per year. In parallel, four different operating regimes were tested to optimize energy utilization and product quality. The optimal regime achieved a heat transfer of 100.07 MW, minimal CO2 and H2O concentrations, and maximum recovery of C3–C5 hydrocarbons. This paper highlights the importance of condition monitoring, targeted inspection strategies, and energy optimization in extending equipment life and reducing operational risks. This approach enhances reliability and cost-effectiveness in oil and gas facilities while prioritizing environmental protection.451-03-136/2025-03/200105, 451-03-136/2025-03/200051, 451-03-136/2025-03/200066, 451-03-136/2025-03/ 200213, 451-03-137/2025-03/20010

Lifetime Corrosion Loss of Bulk Carriers

This paper analyzes the total steel replacement due to corrosion degradation in four Handymax-class bulk carriers, based on corrosion measurements recorded throughout their operational lifespan. Each ship was divided into 11 lightship mass subgroups, enabling detailed examination of cumulative lifetime corrosion losses for both entire ships and individual subgroups. Utilizing similar ship data obtained from the shipyard, the study also provides estimations of the total steel weights of each of lightship subgroups. The findings offer valuable insights into the overall aging effects on ship structures, crucial for maintenance planning, structural integrity assessments, and recycling, especially from the perspective of sustainable shipping. Additionally, the estimated weights of lightship subgroups can serve as reference data for preliminary ship design, aiding in the estimation of lightship weights and potential steel loss due to corrosion

THE INFLUENCE OF CRYOGENIC TREATMENT ON THE HARDNESS OF ROLLING BEARINGS’ BALLS

This study examines the effects of Deep Cryogenic Treatment (DCT) applied after conventional quenching (Q) and tempering (T) on the hardness of rolling bearing balls—a geometric shape that has been significantly less studied compared to other sample forms, such as plates or cylindrical specimens. The primary objective is to determine whether DCT, when applied to commercially available rolling bearing balls (supplied by the manufacturer after completing Q and T), negatively impacts their performance or enhances it. The bearing balls analyzed in this study were from bearing types 6306, 6308, and 6310, manufactured from 100Cr6/AISI 52100 steel. The DCT process involved a controlled cooling rate of 1.5°C per minute, a soaking temperature of -160°C, and a soaking duration of 24 hours. Experimental results revealed that the hardness of the bearing balls remained largely unchanged, with a percentage variation of less than 1% across all tested bearings. Although previous studies on the same bearing material have suggested that DCT can improve hardness, our findings indicate that this effect may not be as significant when DCT is applied to bearing balls after quenching and tempering under the specific conditions of this study. Future research will explore the influence of DCT on additional factors such as dimensional stability, surface roughness, and residual stress to gain a more comprehensive understanding of its overall impact on bearing performance

Influence of Infill Pattern on Ballistic Resistance Capabilities of 3D-Printed Polymeric Structures

Recent technological advances have expanded the use of 3D-printed polymer components across industries, including a growing interest in military applications. The effective defensive use of such materials depends on a thorough understanding of polymer properties, printing techniques, structural design, and influencing parameters. This paper analyzes the ballistic resistance of 3D-printed polymer structures against 9 × 19 mm projectiles. Cuboid targets with different infill patterns—cubic, grid, honeycomb, and gyroid—were fabricated and tested experimentally using live ammunition. Post-impact, CT scans were used to non-destructively measure projectile penetration depths. The honeycomb infill demonstrated superior bullet-stopping performance. Additionally, mechanical properties were experimentally determined and applied in FEM simulations, confirming the ability of commercial software to predict projectile–target interaction in complex geometries. A simplified analytical model also produced satisfactory agreement with experimental observations. The results contribute to a better understanding of impact behavior in 3D-printed polymer structures, supporting their potential application in defense systems

Temporal changes in the flexural properties of 3D-printed ABS specimens

This study investigates the environmental aging effects on 3D-printed Acrylonitrile Butadiene Styrene (ABS) produced using Fused Deposition Modeling (FDM) and Digital Light Processing (DLP) techniques. The materials in filament (FDM) and resin (DLP) forms were exposed to UV light, humidity, and temperature fluctuations over two months. Mechanical testing via three-point bending and Fourier Transform Infrared Spectroscopy (FTIR) were employed to assess the impact of these environmental factors. Results showed notable mechanical strength and structural stability differences between the FDM-printed filament and DLPprinted resin ABS under aging conditions. The filament-based ABS exhibited superior mechanical properties, retaining its strength over time, while the resin-based ABS degraded significantly shortly after printing. Despite exposure to ambient environmental conditions, the chemical composition of both materials remained stable throughout the research period.no. 451-03-65/2024- 03/200105; no. 451- 03-66/2024-03/20002

Carnot battery with steam accumulator and pebble bed thermal energy storage

Carnot batteries can store excess electricity from intermittent renewable solar or wind sources and generate power in periods of peak consumption. A novel design of the Carnot battery is proposed based on thermal energy storage by the combination of a steam accumulator and a pebble bed in a series configuration. During the Carnot battery charging, steam is generated by high temperature heat pumps with CO2 compression cycles, pressurized and superheated by electrically driven steam compressors. The obtained superheated steam flows through the pebble bed porous structure and transfers heat to alumina balls in direct contact. Steam from the pebble bed inflows the steam accumulator. During the Carnot battery discharging phase, the steam outflows the steam accumulator, superheats in the pebble bed and expands through the steam turbine, which is connected to the electric generator for power production. The advantages of the studied Carnot battery are a simple design and operation of the steam accumulator as the thermal energy storage unit, the accumulated steam directly serves as working fluid in the steam turbine and the coupling of the pebble bed with the steam accumulator enables steam superheating that is required for an increased steam turbine efficiency in power generation. Water is low-cost and more convenient in respect to safety, plant engineering and operational aspects in comparison with other working fluids. In addition, there is no need for additional heat exchangers for the heat transfer between the working fluid and the storage medium. Maximum temperature and pressure of the thermal storage medium are 303 ◦C and 0.7 MPa, respectively. The temperature and low-pressure values enable application of mature technology and lower investment costs, where the capacity specific cost of 471 €/kWhe is reached. The presented Carnot battery design is supported with numerical simulations of thermal energy charging and discharging transients in the pebble bed and the steam accumulator with own original and validated modelling approaches. The obtained Carnot battery charging electric power is 9.5 MWe for 6.9 h, while discharging power is 2.3 MWe for 9.4 h, which is suitable for the electric grid power control on a daily period

Design And Development Of Lightweight Stabilization Platform For Multicopters Armament

For the usage of armament that requests precision targeting on mul-ticopters (rotary-wing drones), it is necessary to provide the best possible sta-bilization with some mechanism that, at the same time, must be lightweight. This paper presents a lightweight stabilization platform based on the Stewart platform mechanism. This parallel mechanism (a mechanism that contains a closed kinematic chain) has six degrees of freedom inside the workspace. The platform must be able to stabilize all disturbances due to the flight of the mul-ticopter and must withstand the recoil of armament if it exists