The descriptive geometry constitues the foundation of the engineering sciences, so necessary to the specialists of this field. The aim of this paper is to establish the intersection curve between two cylinders and their unfoldings, by using the programmes:AutoCAD and Mathematica. We used the classical method and we first establish the intersection curve and then the cylinders unfoldings. To do this, we used the AutoCAD program. The same unfoldings can be obtained by introducing directly the curve equations (which are inferred) in Mathematica program.
The structural transformations occurring at tempering for some high-speed steels are a subject of research for which have been dedicated numerous studies. More complex compositions of the high-speed steels were direct consequence of the complexity of structural transformations which occur during heat treatment. On the other hand, current tendency in energy requires maximum efficiency and rational use of heating sources used in industry. Thus, only a precise knowledge of the kinetics of transformations occurring at tempering can be a basis for optimizing this treatment. Although cobalt is used for a long time as an alloying element, though relatively recently it was considered important to the properties of rapid steel. These circumstances, combined with the lack of quantitative information on the kinetics transformation at tempering operation treatment for some steel has led to this paper. The thickness of the studied samples is 5 mm and was taken from the annealed steel bars. These samples were subjected to hardening and tempering treatment in salts bath. Heating for hardening was performed in two steps, at 5500C and 8300C. Austenitizing was done at 12000C, during 120 seconds. The cooling was done up to 5300C in salts bath, with a keeping of 15 seconds, and then air cooling was done. On these samples were carried out, HRC Rockwell hardness measurements, and X-ray diffraction analysis.
In this paper the deformation state of a circular and isotropic plate is analyzed, using as methods of comparison the analytical, the finite element and the experimental element methods. In the finite element method, the plate is analyzed by several programmes, as well as assembled with the respective container.
It is obvious that all the elements in a metallic prosthesis implanted in the human body may have beneficial or detrimental effects on the tissue-prosthesis interference. For this reason, the precise knowledge of the chemical composition and structure of an implantable metallic material becomes a major requirement for estimating the medical prosthesis behavior and minimizing the risk of rejection of the implant by the human body. This paper presents an elemental and structural analysis of some potentially biocompatible materials, such as AISI 316 and Co-Cr-Mo alloys.
The paper proposes to establish the intersection curve and the unfoldings of three cylinders. The intersection of the curves was determined by the classical method, using the AutoCAD program, and the unfolded surfaces were realized by analytical methods. For this the Mathematica program was used.
In this presentation are evidenced instrumental characterization by Electronic Scanning Microscopy (SEM) equipped with EDS / WDS of aluminum alloys such 2024 alloy with multiple synergistic purposes as: acquisition of new knowledge, increase the amount of information obtainable about the material, increasing the efficiency and the quality of the tests, characterization of special destination alloys and assessing their conformity with the specified requirements. In this direction, it requires both the knowledge the test methods (theoretical basis, test method, procedure relating to the method, quality assurance testing) as well material characteristics investigated. These aspects are necessary for test system design, and preliminary interpretation of experimental results.
In this paper is presented a comparative study regarding the synthesis of hydroxyapatite powders. The chosen method of synthesis of this biomaterial was chemical co-precipitation. The structure, size and morphology of the obtained powders were analyzed by X-ray diffraction, infrared spectroscopy - FTIR, dynamic light diffusion DLS tehnique and scanning electron microscopy-SEM. The results obtained were compared with those obtained on a commercial hydroxyapatite powder. Investigation methods have confirmed the synthesis of a high purity hydroxyapatite with a optimal degree of crystallization and crystallinity for the reconstruction and regeneration of hard tissue.
This paper presents the most used processes for the synthesis of hydroxyapatite from aqueous solutions: chemical precipitation, the hydrothermal process and the sol-gel method. The experimental part includes the synthesis of hydroxyapatite by chemical precipitation. The obtained results confirm the obtaining of a ceramic with a high purity and a high degree of crystallization.
Non/oriented electrical sheets are sheets tailored to produce specific properties and are produced from Fe-Si or Fe-Si-Al alloys. Non-oriented electrical steel sheets are incorporated into a wide range of equipment, from the simplest domestic appliances to hybrid and pure electric vehicles. In studying about the magnetic, there have a lot of method can be used for the different experiment requirement such as measuring magnetic flux, nominal loss and other objectives.
During electrical steel processing, there are usually small variations in both chemical composition and thickness in the hot-rolled material that may lead to different magnetic properties for the same steel grade. Therefore, it is of great importance to know the effects of such variations on the final microstructure and magnetic properties of these steels. The purpose of this work was to study microstructural changes of the bands investigated during processing occurring siliceous strips with non-oriented grains. The second aim was to study the influence of grain size on the total magnetic losses at 1.0 T and 1.5 T. Materials 10 rolls intended to be processed into quality electrical steel M400-50A (according to EN 100027-1) were analyzed with metallographic microscope Neophet 32 and the magnetic characteristics was made with Epstein frame according IEC 6040/4-2, with an exiting current frequency of 50Hz at 1.5T and 1.0T induction after aging treatment of 225°C for 24 hours. Sample for light microscopy observation were prepared by polishing and etching in 5% Nital.
This article presents different solutions to reduce natural gas consumptions of the aluminum melting furnaces, through recovery of the heat from flue gases. In order to be able to analyze the recovery solutions, a mathematical model for energy balance of these furnaces was adapted. This mathematical model allows drawing up energy balances together with the main working technique and economical parameters of these types of furnaces, in actual conditions, and the same, under optimizing conditions, by applying recovery solutions.
The mathematical model which can elaborate energy balances for aluminum melting furnaces, was transposed in M. Excel based software, where the quantification of different solutions for natural gas consumption saving is possible. One of the applications of this computer software for an aluminum melting furnace, either for actual working conditions or per upgraded furnace by use an air pre-heater, materials pre-heater, or a regenerative burner system, is presented in this article.