In this paper we applied multi-criteria methods of decision in order to establish the best encapsulation material to be used in producing photovoltaic modules. The encapsulation materials play an important role in establishing the PV module performance, especially if referring to their ability to increase their life time. For our study, we have considered the most widely used encapsulation materials available on the market, such as Ethylene-Vinyl Acetate (EVA), Polyvinyl Butyral (PVB), Thermoplastic Polyurethane (TPU), PolyDimethylsiloxane (PDMS), Ionomer. Amongst of their basic properties, we took into consideration the light transmittance, refractive index, thermal conductivity, volume resistivity, and water vapor transmission rate. In the paper herein, two multi-criteria methods, namely the Simple Additive Weighting method and ELECTRE (ELimination and Choice Expressing Reality) method are applied in order to establish a hierarchy of the mentioned encapsulation materials. It is also shown that the final hierarchy of materials depends on the importance given to the criteria involved. By considering all the mentioned properties and the economical aspect, in particular the cost, the first position in the hierarchy is occupied by EVA. If the cost is eliminated, the hierarchy changes and EVA becomes outranked by other materials, as PDMS and Ionomer.
This paper presents the results of experimental research on the possibility of using bronze chips recovered from the cutting process of the molded sliding bearings to obtain new sintered sliding bearings. This paper presents the results of experimental research on the possibility of using bronze chips recovered from the cutting process of cast sliding bearings in developing new sintered bearings). The cooper-tin alloys have many applications in the industry and they are usually used as antifriction materials to sliding bearings construction. Chips recovered from cooper-tin resulted from the cutting process were used to obtain metal powders in planetary mills. Recovered powders were then compacted to a unilateral mold and then were applied a sintering cycle in argon. To the obtained samples we applied wear tests in conditions of dry friction to prove the possibility of use as anti-friction material for sliding bearings in similar conditions to those obtained from industrial powders.
Hardening laser surface offers new possibilities for the enhancement of the mechanical resistance of superficial layers. Essential for the laser treatment processes is the efficiency at which the incident laser power is coupled into the work piece. The aim of the work was to study the effect of some factors such as spot shape, beam angle of incidence and surface coating on the steel surface absorptivity. Samples made of carbon steel were laser processed using a CW CO2 - 1,2 kW laser unit. Different process parameters (beam power, spot dimension and traverse speed), were used. The microstructure of laser hardened layers which have been investigated by optical microscopy. The mechanical characterization of the layers has been done by hardness measurements. Correlation has been established between the structure of the laser-processed layers and the
process parameters.
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