Fibers play an important role when studying the tribological behavior of reinforced friction composites. The purpose of the current research is to develop a glass fiber reinforced polymer (GFRP) recipe with improved tribological properties as well as to find the composites with the optimal tribological behavior. A ball-on-disc tribometer was used to perform dry sliding friction testing, the obtained results were then analyzed with the ELECTRE (ELimination Et Choix Traduisant la REalite-elimination and choice translating the reality) method based on a utility matrix having process parameters the applied load, sliding velocity, and weight percentage of the fiber content. The ELECTRE method was chosen to find the optimal tribological parameters, with respect to more performance criteria, because it is one of the best multiple criteria decision-making methods. The optimal combination of parameters for the multi-response characteristics of the investigated friction composite was at an applied load of 10 N, a sliding velocity of 0.1 ms⁻¹ and a 54% weight fiber content. The results showed that the addition of glass fiber (GF) content did not considerably improve the tribological behavior of the friction composites. In addition, from the nano focus–optical 3D scanning electron microscopy, images of the friction, tested friction and wear composites, plate formation, fiber-matrix delamination, fiber pull-out, and matrix cracking and damage, various wear mechanisms were identified.

Nanotribological studies of thin films are needed to develop a fundamental understanding of the phenomena that occur to the interface surfaces that come in contact at the micro and nanoscale and to study the interfacial phenomena that occur in microelectromechanical systems (MEMS/NEMS) and other applications. Atomic force microscopy (AFM) has been shown to be an instrument capable of investigating the nanomechanical behavior of many surfaces, including thin films. The measurements of tribo-mechanical behavior for MEMS materials are essential when it comes to designing and evaluating MEMS devices. A great deal of research has been conducted to evaluate the efficiency and reliability of different measurements methods for mechanical properties of MEMS material; nevertheless, the technologies regarding manufacturing and testing MEMS materials are not fully developed. The objectivesof this study are to focus on the review of the mechanical and tribological advantages of thin film and to highlight the experimental results of some thin films to obtain quantitative analyses, the elastic/plastic response and the nanotribological behavior. The slight fluctuation of the results for common thin-film materials is most likely due to the lack of international standardization for MEMS materials and for the methods used to measure their properties.

The transition to a circular economy with an emphasis on eco-innovation is just beginning both in Europe and in Romania, as a member country of the European Union. The whole economic system in which people operate must be circular, which means that it must eliminate conflicting aspects related to regulation, collaboration, governance, supply chain dynamics, and data transparency. However, the barriers to the transition to a circular economy are substantial, and it is up to states to work together to find innovative solutions to society’s problems. This article focuses on aspects related to eco-innovation in the field of drinking water quality in all administrative regions of Romania. In this regard, a study was undertaken, and the main objective pursued in was to identify and highlight the degree of eco-innovation of drinking water suppliers in seven underdeveloped regions of Romania. Starting from an analysis of the water management framework through the OECD Principles on Water Governance, it was possible to develop a study on drinking water supply companies in Romania. This study was performed based on specific indicators grouped by categories, and it aimed in two directions: on the one hand, the identification of drinking water distributors with a high degree of eco-innovation, which leads to quality certification of the drinking water supplied and which has the impact of encouraging household consumers to mainly use this type of supplied water to the detriment of PET bottled water (which has well-known major disadvantages in relation to environmental pollution and user health); on the other hand, the identification of drinking water supply companies with a low degree of eco-innovation, which is proof of the need for mandatory measures to improve drinking water quality, measures that can be taken at the supplier level but especially with support from the administrative and political environment.

Multibody mechanical systems (i.e., serial, and parallel robots) have a wide range of applications in the industrial field. In technological processes, these systems perform mechanical movements, in which the active forces have a certain time variation law and, hence, induce higher-order accelerations in the mechanical system, which become central functions in acceleration energies. The advanced dynamics study of multibody systems, often characterized by symmetry, is conducted by applying the differential and variational principles. Lagrange–Euler equations and their time derivatives are commonly used. Here, the central function is the kinetic energy and its higher-order time derivatives. Additionally, the generalization of Gibbs–Appell equations, where the central function is represented by the first and higher-order acceleration energy, can be applied. This paper aims to establish a relation between the kinetic energy and acceleration energy for different material systems. This purpose is achieved by applying the absolute second-order time derivative on the expressions of kinetic energy, corresponding to different material systems. Following this differential calculation and by applying some constraints, the relationship between kinetic energy and acceleration energy is obtained. For validating the relation between kinetic energy and acceleration energy of the first, second and third order, an application is presented.

Symmetry plays an essential role for generating aesthetic forms. The curve is the basic element used by designers to obtain aesthetic forms. A curve with a linear logarithmic curvature graph gradient is called aesthetic curve. The aesthetic value of a curve increases when its gradient is close to a straight line. We introduce the notions of approximate aesthetic curves and approximate neutral curves and obtain estimations between the curvature of an approximate aesthetic/neutral curve and an aesthetic curve.

This paper presents research conducted in the direction of analyzing the efficiency of filters used for drinking water intended for domestic consumption, with effects on the water quality gained from the public distribution network. A basic method that uses accessible techniques, such as optical microscopy and tests that involve the use of existing products on the consumer market, was developed regarding the filtration capacities of the main filters existing on the market—a method that has advantages, such as speed and ease of application, a unitary character in obtaining samples, low costs, and high efficiency. The technique approached is that of microscopy, and the samples used were taken from the laboratory tests made on the mentioned filters, using a specific experimental stand designed to support laboratory tests by using chosen filter cartridges. The research results obtained were analyzed to make a classification from the perspective of filtration efficiency, in terms of using statistical analysis tools (mathematical models and methods processed in MATLAB software). Moreover, by using a certain type of application based on specific mathematical algorithms, which takes into account some influential factors with a decisive role on household consumers, it was aimed to identify the optimal filter element for acquisition and use in its own regime. The aim of the study was to identify the optimal filter cartridge from the perspective of quality–price ratio.