This paper presents a detailed kinematic analysis of a double-toggle jaw crusher used for the primary crushing of hard and bulky materials. The study introduces an innovative mathematical modeling method for the motion of the mechanism’s components, eliminating the need for traditional decomposition into structural groups. General equations are developed to determine the positions, linear velocities, and angular displacements of the moving elements, providing a solid foundation for equipment design and study. The generated mathematical model was validated using real-world dimensions of an SMD-117-type jaw crusher and by comparison with simulation results obtained from Mathcad, Linkage, Roberts Animator, and GIM software. The results demonstrated a high degree of agreement between the calculated and simulated trajectories and linear velocities. The analysis of angular displacements and linear velocities confirmed the cyclic nature of the mechanism’s motion, characterized by sinusoidal variations and low oscillations, which are relevant for assessing variable loads. Through its rigorous approach and multi-source validation, the research makes a significant contribution to the development of more efficient, durable, and adaptable jaw crushers for modern industrial requirements.

This article presents some of the results obtained from a study aimed at identifying the level of public information regarding the waste management system. Many articles have been identified in the literature analyzing the solid waste management system. Although this service is mainly provided to the population, not as many articles were found that focus on interviewing the population about the solid waste management system. This article presents a study conducted between 12 December 2022 and 14 January 2023, specifically in the Șerbănești neighborhood in Bacău, Romania. The purpose of the study (a questionnaire-based study) was to identify the population’s satisfaction with the solid waste management system in the analyzed area, as well as the level of information and its accessibility. The data were obtained from an electronic questionnaire created using Google Forms and distributed online. A small number of the questions were aimed at obtaining information about those who participated in filling out the questionnaire, but the majority focused on gathering information from the population about the waste management system. After processing the data generated by 191 respondents, a series of specific insights about the collection system were obtained. Among these, it was identified that, on average, 58% of the population is satisfied with the sanitation service. Regarding the information and awareness activities carried out by the sanitation operator, approximately 52% of the respondents hold a positive opinion. However, when analyzing access to information channels, it was observed that 49.7% of the respondents lack access, and if we consider the sample of respondents who are unaware of their existence, the value reaches 57%. It is recommended that, as a result of this study, this type of research be extended to the entire municipality of Bacău in order to obtain an overview of the waste management system.

In this paper, a study that describes the mathematical analysis of a mechanical gripping system with a lifting-tong-type mechanism is presented. The study involves the geometrical analysis of the investigated mechanism. What distinguishes this work from other studies in the specialized literature is the way the analysis of the mechanism under study is carried out. Specifically, the working methodology proposes the analysis of the entire mechanism and not its decomposition into structural groups, thus obtaining complex mathematical equations. By using values, the mathematically obtained results were able to describe the movement of the mechanism’s components, as well as the variations in their velocities. To verify the correctness of the results, a simulation was carried out using the Linkage simulation software.

This article presents a comparative study of two different kinds of processes that produce oscillatory motion on a work surface during the mechanical separation process. The investigation began with determining the trajectory produced by the oscillating separator’s active component of the classical drive mechanism. Based on this, a second mechanism—the six-bar mechanism—was created using the WATT program, and a mathematical analysis was conducted. The comparative examination of the two mechanisms was carried out using OriginPro, Mathcad, and Roberts software. This study’s findings all point to the same conclusion: the newly developed mechanism produces the same trajectory as the classical mechanism when viewed through the lens of the reference element, or the element that causes the oscillatory movement. However, when looking at the operating parameters, there was a noticeable difference in the movement’s speed and the angle of the crank when producing its maximum speed. Theoretically, this new mechanism increases the speed at which solid particles move across a work surface. However, this difference cannot be characterized as positive or negative because further research is required to determine how the nature of solid particles and the work surface’s inclination affect this process, in addition to this mechanism. The identification of the mathematical equations of motion for the constituent parts of the mechanism under study is the novelty produced of this paper.

This study presents a comparative analysis of two double-toggle drive systems for jaw crushers that are tension based and compression based (this refers to the way in which the connecting rod is mechanically stressed within the drive mechanism), with the objective of identifying the optimal configuration from both kinematic and functional perspectives. Jaw crushers play a critical role in the extractive industry, and their performance is strongly influenced by the geometry and positioning of the drive mechanism. A theoretical approach based on mathematical modeling and numerical simulation was applied to a real constructive model (SMD-117), assessing variations in the linear velocity of the moving links as a function of mechanism placement. The study employed Mathcad 15, Roberts Animator, and GIM (Graphical Interactive Mechanisms) 2025.4 software to perform calculations and simulate motion. Results revealed a sinusoidal velocity pattern with significant differences between the two systems: the tension-based drive achieves peak velocities at the beginning of the angular variation interval, while the compression-based system reaches its maximum toward the end. Link C consistently exhibits higher velocities than link E, indicating increased mechanical stress. Polar graphic analysis identified critical velocity angles, and simulations confirmed the model’s validity with a maximum error of just 1.79%. The findings emphasize the importance of selecting an appropriate drive system to enhance performance, durability, and energy efficiency, offering concrete recommendations for equipment design and operation.

The article describes the results obtained by the authors in sludge dewatering through new processes and evaluating their performance. The research is part of sustainable development by valorizing the sludge and agricultural waste in composite materials with applicability in the constructions from rural areas. The main method of sludge dewatering tested in this research is vibratory sieving dewatering. The experimental research examined three variable parameters: initial sludge moisture, sieve angle, and the engine speed causing sieve vibration. A three-factorial experiment was performed with four values for each of the three parameters considered, and the results were processed using descriptive and inferential statistics. Absolute and relative dewatering depend the most on the initial sludge moisture and sieve tilt angle. In conclusion, it was found that dewatering by vibrating sieving can achieve an almost double range of values for absolute performance, compared to pressing dewatering. However, the efficiency of dewatering by pressing is superior to dewatering by vibratory sieving. As a matter of absolute values, the two dewatering processes that were studied and described in this article perform below the values achieved by the classical processes: natural, thermal, and mechanical.