Răzvan Bogdan Itu

Navigable waterways are essential for transportation, trade, and regional development, yet they are increasingly affected by oil pollution generated by intensive maritime traffic and industrial activities. Oil contamination threatens aquatic ecosystems, reduces water quality, and affects biodiversity and economic activities dependent on river systems. This study proposes an innovative and sustainable solution for oil spill mitigation through the development of a solarpowered autonomous or semi-autonomous boat designed to collect oil from the water surface and convert the recovered waste into biodiesel.The proposed system integrates floating collection arms, an oil–water separation unit, a filtration system, and a hybrid solar-electric propulsion system that enables energy-efficient and environmentally friendly operation. The concept is tested for potential deployment on the Danube River, one of Europe’s most important navigable waterways, particularly in areas affected by oil pollution from commercial vessels.The system performance is evaluated based on oil recovery efficiency, separation and filtration performance, and improvements in water quality parameters. Results indicate that the system could recover up to 80–90% of surface oil, while separation and filtration processes may achieve efficiencies above 95% and 98%, respectively. In addition to reducing pollution, the recovered oil can be processed into biodiesel, supporting circular economy principles and contributing to sustainable waterway management.

This study explores the role of native vegetation in the rehabilitation of mining sites in the Jiu Valley, a region significantly impacted by coal mining activities. The primary objective is to evaluate effective approaches and strategies for re-establishing ecosystems disrupted by mining. A mixed-methods research design is employed, combining field studies and community surveys to assess the ecological benefits of utilizing native plant species in reforestation efforts. The methodology includes soil analysis, biodiversity assessments, and the monitoring of vegetation growth post-planting. Preliminary outcomes indicate that the introduction of native flora significantly enhances soil stability, improves biodiversity, and restores ecosystem functions. Key results show a marked increase in local species diversity and a reduction in erosion rates in areas where native vegetation was established. The findings highlight the importance of integrating native plant species into rehabilitation practices, emphasizing their role in promoting sustainable land use and ecological restoration in the Jiu Valley. The study concludes that adopting native vegetation is essential for effective mining site rehabilitation, providing a sustainable pathway for restoring affected landscapes and supporting local communities.

Land surface undulation represents a promising agroecological strategy to enhance orchard productivity and resilience, especially in sloped or degraded terrains. This study explores the role of controlled soil undulation in increasing effective cultivable area, improving resource efficiency, and mitigating the agricultural carbon footprint. Using a geometric modeling approach based on the Pythagorean theorem, we quantified surface area gains across slopes ranging from 1° to 20°, with results indicating up to 6.4% surface increase at 20°. Field data from the Jiu Valley, Romania—an area with post-mining degradation and complex topography—were used to evaluate the practical applicability of undulation techniques. Findings suggest that increased land surface enables higher planting density, better water retention, and reduced erosion, contributing to improved yields and soil carbon sequestration. The integration of undulation with contour farming, terracing, and precision technologies (e.g., GPS mapping, soil sensors) further enhances sustainability outcomes. This approach supports the functional restoration of marginal lands and aligns with climate-smart agricultural practices. The study concludes that soil undulation, when contextually implemented, provides measurable ecological and economic benefits, offering a scalable model for sustainable orchard development in varied geographic conditions.

The machines with bucket wheels used to remove and to put coal in deposits are intended to dump and remove coal from quarries and power station deposits. The paper presents how to determine the gravity center of a machine with bucket wheels used to remove coal from deposits, by tensiometric measurements, in various positions of the arm of the bucket rotor (wheel). The machine with bucket wheel used for taking out from deposits is within Arcelor Mittal Galați. The measurements have been made in limit positions of the arm of the bucket wheel, horizontally and vertically, respectively, and have been made because of determining an additional weight that should be added in the ballast box of the equilibrium arm, if appropriate.

This paper explores the integration of two essential sustainability concepts—reuse and conversion—into primary and secondary school education. These concepts are key components of the circular economy and directly align with Sustainable Development Goal 12: Responsible Consumption and Production. Reuse focuses on extending the life of products by utilizing them multiple times without reprocessing, whereas conversion involves transforming waste or unwanted materials into new products with added value. Through practical activities, such as creative reuse projects and innovative conversion initiatives, students can gain a handson understanding of how these principles help conserve resources, reduce environmental impact, and lower production costs. The paper highlights the significant role of education in promoting green thinking from an early age, equipping students with the knowledge and skills to make responsible choices that benefit both the economy and the environment. By fostering awareness and encouraging sustainable practices in schools, this approach aims to instill lifelong ecological responsibility in young learners, preparing them to address future environmental challenges. The analysis also draws comparisons between industrial applications of these concepts and their potential to inspire sustainable behavior among students.

Interdisciplinarity encourages students to make connections between different academic disciplines, fostering a deeper understanding of complex real-world problems. By integrating various subjects, students are able to develop critical thinking skills and apply their knowledge in practical ways. This approach not only enhances their learning experience but also prepares them for the challenges they may face in their future careers. In the paper, a strong connection between mathematics and mechanics has been demonstrated. It is important to note that the discussion of this topic is just scratching the surface of the many aspects that can be explored. This example highlights the principle of continuous learning and the endless possibilities for acquiring new knowledge in any field. The process of knowledge is infinite and always open to new contributions. By integrating knowledge from different disciplines, individuals can gain a holistic understanding of complex concepts and phenomena. This interdisciplinary approach fosters critical thinking skills and encourages creative problem-solving, enabling learners to tackle real-world challenges with a broader perspective. Additionally, the collaboration between disciplines promotes innovation and encourages the development of new ideas and solutions. This paper presents aspects regarding the application of the collinearity property in mechanics. The laws of motion of a rigid body, scalar functions of time are meant, which determine, in any moment of the motion, the position of the body in relation to a benchmark through the examples taken in the study were taken from point kinematics and rigid kinematics, also studying how the velocity and acceleration of the points of the solid body vary, in relation to the same reference system.

Tailings dams are special constructions that are part of a complex of works related to the installations for preparing mining masses. These constructions play a role in the mechanical treatment of wastewater and the safe storage of sterile material resulting from ore processing. The closing and greening of tailings dams is achieved taking into account the general stability of the pond and its related constructions, as well as the integration into the surrounding environment of the surfaces occupied by mining waste deposits (tailings dams). This study presents the results of the hydrogeotechnical and stability study carried out on the Gura Roşiei tailings dam location. This analysis aims to evaluate the stability degree of the three compartments that comprise the tailings deposit in order to carry out the closing and greening works of the tailings dam, and to conclude whether the idea of raising them by 1.5–2 m with tailings is feasible. This study was based on field observations, geotechnical drilling, and physical–chemical analyses of the collected samples. Due to the shallow depth, the drilling could not highlight a hydrostatic level except for the areas with excess humidity, areas represented by certain lenticular intercalations of sandy dust that yield water very slowly. These areas are not continuous and cannot define a reference hydrostatic level. All situations were analyzed by four different methods that satisfy the static equilibrium of forces or moments (Bishop and Janbu) or simultaneously of forces and moments (Spencer and Morgenstern–Price). From the point of view of the stability calculations performed in the hypothesis in which the three ponds become active for the storage of tailings, assuming a corresponding piezometric level, the resulting safety factors are relatively close to the standard values (Fs ≥ 1.4) for the static analysis, and in seismic conditions, they are at the limit of equilibrium. The NE slope of pond No. 2 shows values below the standard safety limit for this type of work. Moreover, tailings dam No. 3 presented from the calculations as being totally inadequate for the elevation. From the obtained results, it was found that the location formed by the three compartments that comprise the Gura Roşiei tailings dam presents major disadvantages for a future storage of flotation tailings, being at the same time an imminent danger to the environment. Due to its reduced capacity to release water from its pores, the settled material is still in a saturated state, and it is assumed that the foundation land, comprised of the terrace deposits of the Abrudel River, is clogged at the interface with the settled material and unable to naturally drain the excess moisture from the dam’s body.