Adrian M.L.,University of Bacau
Applied Mechanics and Materials | Year: 2013
In small and medium batch series manufacturing the small tool and workpiece changing time is one of the main objectives to follow in obtaining high productivity. These auxiliary times are defined as the times consumed with preparing and changing the next tool or workpiece to follow the machining process, times that usually overlap the machining process. For this purpose machining centres are equipped with an automatic tool changer system and an automatic pallet changer system. The palletizing systems imply eliminating the times consumed with the alignment, fixing and clamping of the workpieces, these systems consisting of several mechanisms: the pallet, the automatic pallet changing mechanism, the positioning mechanism and the pallet clamp/unclamp mechanism. In this paper we present an general overview of the automatic pallet changing mechanisms used both in flexible manufacturing systems and machining centres. © (2013) Trans Tech Publications, Switzerland.
Mocanu M.,University of Bacau
Complex Analysis and Operator Theory | Year: 2011
We prove a Poincaré inequality for Orlicz-Sobolev functions with zero boundary values in bounded open subsets of a metric measure space. This result generalizes the (p, p)-Poincaré inequality for Newtonian functions with zero boundary values in metric measure spaces, as well as a Poincaré inequality for Orlicz-Sobolev functions on a Euclidean space, proved by Fuchs and Osmolovski (J Anal Appl (Z. A. A.) 17(2):393-415, 1998). Using the Poincaré inequality for Orlicz-Sobolev functions with zero boundary values we prove the existence and uniqueness of a solution to an obstacle problem for a variational integral with nonstandard growth. © 2010 Birkhäuser / Springer Basel AG.
Stefanescu I.A.,University of Bacau
Scientific Study and Research: Chemistry and Chemical Engineering, Biotechnology, Food Industry | Year: 2015
The aim of present study was to characterize the bioaccumulation capacity of heavy metals by Bacillus megaterium from phosphogypsum waste. The Bacillus megaterium strain (BM30) was isolated from soil near the phosphogypsum (PG) dump. For the bioaccumulation quantification produced by BM30 strain were used three experimental treatments respectively with 2, 6 and 10 g·L-1 PG. Cellular biomass samples were collected punctually at ages corresponding to the three stages of the development cycle of the microorganism: exponential phase, stationary phase and decline phase and the heavy metals concentrations were measured by atomic absorption spectroscopy. The bioaccumulation yields in cell biomass, relative to the total amount of analyte introduced in the reaction medium were between 20 - 80 %, the lowest value was recorded by Cu and highest by Mn. The study results indicated that the isolated strain near the dump PG, BM30, bioaccumulate heavy metals monitored in cell biomass in the order Cu > Fe > Zn = Mn. © 2015 ALMA MATER Publishing House, “VASILE ALECSANDRI” University of Bacău. All rights reserved.
Ciubotariu V.A.,University of Bacau
Advanced Science Letters | Year: 2013
The aim of this paper is to investigate and understand the energy absorption behavior and progressive buckling phenomenon regarding thin-walled structures under quasi-static/dynamic axial compression. Plastic strain, strain hardening and thickness variation within the materials are strongly influencing the collapsing mode of these thin-walled structures. Also, it was concluded that circular structures are best fitted for quasi-static loadings and rectangular structures are best fitted for dynamic loadings. Parameters like the strain hardening, absorbed energy or the specific energy absorption of the materials within the tailor welded blanks and the features of the collapse modes are described and analyzed. It was found that the use of tailor welded blanks structures is an effective way to improve the crashworthiness of thin walled structures. © 2013 American Scientific Publishers.
Radu M.C.,University of Bacau |
Cristea I.,University of Bacau
Materials and Manufacturing Processes | Year: 2013
The effects of four working parameters, namely tool diameter, tool vertical step, feed rate, and spindle speed on the dimensional accuracy, surface roughness, and microstructure of parts processed by SPIF were experimentally investigated. The parts were made from carbon steel (DC01), stainless steel (304), and aluminium (A1050). Two geometries were tested - a conic and a prismatic shape. The results were statistically processed by using the ANOVA technique. It was highlighted that the working parameters have contradictory influence on the analyzed quality characteristics of parts and only a proper combination of them could lead to the expected results. © 2013 Copyright Taylor and Francis Group, LLC.