The technological change to LEDs is an unstoppable reality which, little by little, is becoming increasingly important in terms of the lighting inside and outside our homes. The exterior lighting of our cities is moving decisively and clearly towards the incorporation of this technology in urban spaces. The energy efficiency, light quality, and economic benefits of LED technology are an unquestionable reality. This is causing public administration projects involving large-scale switches to LEDs to be promoted and financed; however, it is beginning to be observed that the commitment to the policies decided by this technology should take into account some environmental aspects which have not been studied to date. The environmental impact of the substitutions is caused by the need to valorize the replaced luminaires. Until now, most have been stored without the possibility of use, reuse, or recovery. The environmental impact produced in the manufacture of LED luminaires that replace the old sodium vapor (VSAP) or metal halide (MH) discharge lamps must also be considered. In addition, in the administrative clauses specifications that govern the public tenders, it is observed that the fundamental environmental aspects both of recycling the old lamps, and of the life cycle analysis (LCA) of the luminaires that are replacing them, have not been contemplated or valued with sufficient weight. In addition, there are very few public substitution contests in which environmental criteria are rewarded or valued in an important way. This work intends to summarize a methodological proposal using the techniques of multiple decision-making criteria for the selection of bidding companies for public outdoor lighting competitions. We propose the use of the PROMETHEE method multi-criteria analysis for the application of the most commonly used criteria for the luminaire LED selection process, including an environmental impact assessment with LCA techniques, and propose this as a case or model guide in the public contests of cities. A model of the bidding conditions that addresses and assesses the environmental aspects which are absolutely key to sustainable development is supported by the ecological criteria of the circular economy.

Build time is a key issue in additive manufacturing, but even nowadays, its accurate estimation is challenging. This work proposes a build time estimation method for fused filament fabrication (FFF) based on an average printing speed model. It captures the printer kinematics by fitting printing speed measurements for different interpolation segment lengths and changes of direction along the printing path. Unlike analytical approaches, printer users do not need to know the printer kinematics parameters such as maximum speed and acceleration or how the printer movement is programmed to obtain an accurate estimation. To build the proposed model, few measurements are needed. Two approaches are proposed: a fitting procedure via linear and power approximations, and a Coons patch. The procedure was applied to three desktop FFF printers, and different infill patterns and part shapes were tested. The proposed method provides a robust and accurate estimation with a maximum relative error below 8.5%.

Pocketing operations are common in automotive and aerospace industry. An efficient operation in terms of cost and quality requires the selection of an adequate strategy: tool-path, cutting speed, rpm etc. Two methods help in this task, numerical simulations and experimental measures. This work explains how to compare planar pocketing tool-paths by measuring the milling table acceleration. An experimental setup with a tri-axial accelerometer glued to the milling table, an open-source acquisition card programed in C language, and a post processing procedure (calibration plus filter) are the main components of the proposed method. Three pocketing strategies (zig-zag, contour, spiral) are performed to understand the comparison methodology. The proposed solution has an easier implementation and it is cheaper than dynamometer systems, whereas it provides similar information. Note that this is an initial study and further tests are needed to demonstrate its potential