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Open access

Prapawan Thongsri

Abstract

Calcium manganese oxide (CaMnO3) polycrystalline was synthesized by solid state reaction (SSR) and hot-press (HP) methods. The powder of CaCO3 and MnO2 were mixed by ball milling then calcined at 850°C for 10 h and hotpressing at 850 °C for 1 h to obtain the CaMnO3 samples. The crystallography of the samples was analyzed by the X-ray diffraction (XRD). The microstructures of the samples were observed by scanning electron microscope (SEM). It was found that, the sintering process influence the crystalline perfection and have a direct impact on the mechanical properties of CaMnO3 and their aging behavior. The values of the effective elastic modulus was 6 GPa and Flexural strength was 0.417 MPa of CaMnO3 were found to be in the range of corresponding values for high performance and possibility fabricated n-type thermoelectric leg.

Open access

Dragoş Viorel Brezoi

Abstract

The paper presents a micro encapsulation method of α-Fe2O3 nanoparticles in PEG4000. A suspension of α-Fe2O3 nanoparticles and dissolved PEG is sprayed through a nozzle at atmospheric pressure. After rapid expansion, core-shell composite microparticles that don´t tend to agglomerate are obtained. Structure and morphology were investigated by electronic microscopy (TEM and SEM), X-ray diffraction (XRD), and spectral technique (UV-Vis and FTIR).

Open access

Dorin Angelescu and Gheorghe Ion Gheorghe

Abstract

As a result of the scientific concerns of the Doctoral School of Mechanical Engineering and Mechatronics at Valahia Târgovişte University in the field of robotics dedicated to security and surveillance, the scientific work "Intelligent Cyber- Mixmechatronic Micro-System for Monitoring and Controlling the Security and Surveillance Robots" is in the testing and experimentation phase, within the doctoral (industrial) thesis "Studies, research and contributions regarding the realization of a smart mecatronic robot for security and surveillance applications". The scientific work results in a highly efficient cybermixmecatronic system, unique in Romania, which will be used to control the mechatronic security and surveillance robot, respectively the propulsion and control of its displacement. The robot is controlled through Artificial Intelligence, using the Internet of Things (IoT), which is why the Intelligent Motion Control system must be optimized both in terms of response speeds and energy. At the same time, due to the varied and possibly unstable conditions of the displacement field, the system must meet stringent criteria of reliability, resilience, weather, stability and redundant solutions for on-site repair of potential failures during missions. The cybermixmecatronic system designed to move the robot must carry it safely at the mission site so that it can then return it back to the Command and Control Center. In the paper will be presented the original solution, applicable with minimum of specific modifications (according to the chassis used), to any type of robot requiring both operator-controlled or autoguid control. Thus, a complex project will be realized combining into a unitary Mechatronics, Integronics, Cyber-Mixmechatronics, Artificial Intelligence and Information Technology.

Open access

Ionel Rusa, Cornel Marin and Marius Baidoc

Abstract

The implementation of proactive maintenance is a necessity required by the development of modern technologies for the monitoring and exploitation of energy facilities and equipment. An important advantage of proactive maintenance is to permanently monitor the technical condition of the plant and equipment by vibration measurements and in the correct diagnosis in order to reasonably plan the required repairs. Turbo-aggregates are autonomous complex installations for producing electricity in refineries that operate in high power and high-speed modes. To monitor and control turbine vibrations, vibration sensors (uniaxial, biaxial and triaxial accelerometers) and proximity sensors (for relative displacements and lasers) are columned on bearing housings that transmit signals to data acquisition and processing systems as well is the Vibro-Expret diagnosis system presented in this paper.

Open access

Carmen Popa, Violeta Anghelina and Octavian Munteanu

Abstract

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.

Open access

Ileana Nicoleta Popescu and Ruxandra Vidu

Abstract

The basic purpose of compaction is to obtain a green compact with sufficient strength to withstand further handling operations. The strength of green compact is influenced by the characteristics of the powders (apparent density, particle size and shape, internal pores etc.), the processing parameters (applied force, pressing type, and temperature) and testing conditions (strain rate etc.) Successful powder cold compaction is determined by the densification and structural transformations of powders (metallic powders, ceramic powders and metal-ceramic powder mixtures) during the compaction stages. In this paper, for understanding the factors that determine a required strength of compacted metal-ceramic powder mixtures, we present the densification mechanisms of different mixtures according to densification theories of compaction, the elastic-plastic deformations of mixture powders, the stressstrain relations and the relaxation behavior of compacted metal-ceramic composite parts and the particularities of each of them.

Open access

Dănuț Iulian Stanciu, Gheorghe Gheorghe, Daniela Cioboata and Aurel Abalaru

Abstract

Harmonic analysis is a mathematical method that performs the determination (approximation) of continuous functions by the sum of ideal sinusoids. By selecting these sinusoids in a judicious way, in defining the methods of smart measurement of a part, it is possible to separate the geometrical elements of a part into geometric elements of the shape (circularity, eccentricity, etc.) of the geometric elements corresponding to the state surfaces. This article, using the research carried out under the doctoral thesis “COMPLEX STUDIES, RESEARCH AND EXPERIMENTATION OF PRECISION MECHANICAL GEARING TRANSMISSIONS USING HIGH PRECISION HARMONICS METHODS ”, aims to perform an original work and thus to present and analyze the main methods of processing the data gathered in the process measurement of the parts made and used in mechatronic equipment by resorting to harmonic analysis.

Open access

Dan Nicolae Ungureanu, Daniela Avram, Nicolae Angelescu, Adrian Catangiu, Florina Violeta Anghelina and Veronica Despa

Abstract

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.

Open access

Ileana Nicoleta Popescu and Ruxandra Vidu

Abstract

Powder mixtures compaction behavior can be quantitatively expressed by densification equations that describe the relationship between densities - applied pressure during the compaction stages, using correction factors. The modelling of one phase (metal/ceramic) powders or two-phase metal-ceramic powder composites was studied by many researchers, using the most commonly compression equations (Balshin, Heckel, Cooper and Eaton, Kawakita and Lüdde) or relative new ones (Panelli - Ambrózio Filho, Castagnet-Falcão- Leal Neto, Ge Rong-de, Parilák and Dudrová, Gerdemann and Jablonski. Also, for a better understanding of the consolidation process by compressing powder blends and for better prediction of compaction behavior, it's necessary the modeling and simulation of the powder pressing process by computer numerical simulation. In this paper are presented the effect of ceramic particles additions in metallic matrix on the compressibility of composites made by P/M route, taking into account (a) the some of above mentioned powder compression equations and also (b) the compaction behavior modeling through finite element method (FEM) and discrete element modeling (DEM) or combined finite/ discrete element (FE/DE) method.

Open access

Elena Valentina Stoian, Vasile Bratu, Cristiana Maria Enescu and Carmen Otilia Rusanescu

Abstract

The paper presents the study of internal defects resulting from the continuous casting of steels. The 50 samples were taken from a total of 20 continuously cast bits of different steel grades. The investigation of the causes of internal defects, shown on the analyzed samples, started from the assumption that the secondary metallurgy was performed correctly. The following internal defects have been evident: internal cracks (axial cracks, section cracks), central porosity and marginal punctuation impurities.