Authors:Ahmed A. Hashim, Khalil I. Mahmoud, and Hussein M. Ridha
In embedded systems that necessarily require a steady source of power and (or) attaches to a sensor(s), there are opportunities to mix small batteries to supply such power. The aim of this research is to optimize the geometry and shape of piezoelectric cantilevers to harvest more power. Several piezoelectric cantilever geometries with various shapes (rectangular, triangular, circular, and trapezoidal cross section) are tested in COMSOL multiphysics simulator to find the best geometry that provides the highest accomplishable power. The most efficient geometry was found to be conferred by the trapezoidal, cross section cantilever. Next, another improvement method was applied to maximize the harvested power of the cantilever by modifying the shape of the trapezoidal cantilever structure through increasing the number of its faces. The results demonstrated that the highest output power (36 mW) was produced by the four faces, trapezoidal cross section design of cantilever.
Authors:Odhise Koça, Anis Sulejmani, and Klodian Dhoska
In this paper the generalized model of contact of two plan bodies that roll and slide or just roll is presented. The analytical solution of the correct distribution of pressure in the contact is realized in the presence of the normal compressive force, which realizes the contact, as well as of the force pair or of a tangential force. This model can be used on sprocket teeth due to sliding rolling or rolling itself on the gear pole. The results obtained have been experimentally confirmed by many researchers as well as by the damage that the wheels actually suffer from the teeth.
The behavior of box-shaped columns under heating is investigated. For this purpose, the various sections of thin-wall box-shaped columns were modeled and verified in different temperature ranges by ABAQUS software. The results of this research showed that increasing the thickness leads to increase the buckling stability of column under temperature change. Since the behavior of column will be better than thinner columns under climate change because of the increase in the modulus of elasticity. The solid columns have better buckling stability than hollow columns in normal conditions.
This paper introduces research on magnetic fields with special attention to developing a new method for braking fast-changing alternating movements. This work is part of a research project aiming to find the most efficient and accurate method for development of linear magnetic brake for dynamic tests in industrial applications. In applications requiring precisely defined and generated characteristics of the braking force, highly reliable and accurate function between the braking force and the controlling current should be investigated.
The goal of this research is to develop accurate and reliable control methods for fast changing magnetic fields used in automatic test solutions of different devices and tools, which have been tested manually before.
In the research projects and industrial projects severe optimization problems can be met, where the number of variables is high, there are a lot of constraints, and they are highly nonlinear and mostly discrete issues, where the running time can be calculated sometimes in weeks with the usual optimization methods on an average computer. In most cases in the logistics industry, the most robust constraint is the time. The optimizations are running on a typical office configuration, and the company accepts the suboptimal solution what the optimization method gives within the appropriate time limit. That is, why adaptivity is needed. The adaptivity of the optimization technique includes parameters of fine-tuning. On this way, the most sensitive setting can be found. In this article, some additional adaptive methods for logistic problems have been investigated to increase the effectivity, improve the solution in a strict time condition.
Authors:Michal Marton, Ján Ilavský, and Danka Barloková
Pesticides as one of the micro-pollutants present a great problem and threat to the environment and human health. They can infiltrate the sources of drinking water by application on the agricultural fields. This article is focused on Atrazine, Terbuthylazine and their metabolites. It is their complex structure that makes them hard to degrade naturally and, thus, water needs to be treated before safe using. Therefore, this article studies adsorption on the two granular activated carbons Filtrasorb 400 and Norit 1240 W. For the determination of the concentration liquid chromatography was used. In this article it is presented that Filtrasorb 400 efficiency (26–40% and 33–45% for atrazine and terbuthylazine respectively) is better than the efficiency of Norit 1240 W (9–27% and 10–24% for atrazine and terbuthylazine respectively).
Authors:Hasnae Boubel, Oumnia Elmrabet, Elmehdi Echebba, and Mohamed Rougui
This study is concerned to the investigation of the stability of bridges by taking into account the soil structure interaction and their impact on the dynamic behavior of the structures. The bridge studied is localized at PK 318 + 750 at the national level, between the city of Al Hoceima and Kasseta (Morocco). The analyses are carried out with the ANSYS code demonstrated that for conditions of support, the distribution of displacements and the fundamental frequency for each type of soil change according to its mechanical properties. This work also indicates that the proximity of the fundamental frequencies of the soil structure and strongly influences the soil-structure interaction.
Authors:Martin Vavruš, Peter Koteš, František Bahleda, and Jozef Jošt
Concrete structures that are influenced by degradation, overloading, the thawing, and freezing cycles, corrosion of reinforced bars, should be repaired or strengthened. Each of the mentioned influences lead to decreased load-carrying capacity of the structure or its member. Exceeding the load-carrying capacity leads to mechanical damage of members or excessive deformation. The damaged member has to be strengthened to the required level of reliability and load-carrying capacity. There exist many types and methods of strengthening the columns. This research work deals with strengthening of columns by concreting a new layer of fiber concrete. When applying that type of strengthening, it is necessary to assure the contact between the old layer and the new one. The paper deals with analysis of different types of contacts and determination of their parametric values.
In line with the energy development strategy of Europe, it is necessary to implement energy efficient buildings, in which the external enclosures are converters of solar energy to thermal. Therefore, the purpose of the publication was the scientific substantiation and development of the solar heating system with the use of rooftop solar panels. Graphical and analytical dependences of the coefficient of thermal efficiency of the solar panel in heat supply system from the angles of solar radiation incoming and the density of the radiation flux were obtained. Analysis of the results showed that the coefficient of thermal efficiency of the solar panel without transparent coating with the placement of pipelines of the circulation circuit of the coolant over the heat absorber increases by 50%.