Thermal characterization methodology for dry finishing turning of SAF 2507 stainless steel based on finite element simulations and surrogate models

This paper addresses the numerical thermal characterization of a 3D turning process of a SAF 2507 stainless steel. A thermographic test campaign was conducted to measure the temperature distribution at the tool-workpiece interface. The campaign was accommodated by means of a L18 fractional factorial design of experiment. The 3D turning process was simulated using the software TWS Advantedge. The heat transfer numerical coefficients were calibrated against experimental measures to obtain temperature values as accurate as possible. A statistical methodology framework was adopted to study the dependence of the coefficients from the machining parameters. A heat transfer surrogate model was then built and next experimentally validated

Continuous and discontinuous phase transitions and partial synchronization in stochastic three-state oscillators

We investigate both continuous (second-order) and discontinuous (first-order) transitions to macroscopic synchronization within a single class of discrete, stochastic (globally) phase-coupled oscillators. We provide analytical and numerical evidence that the continuity of the transition depends on the coupling coefficients and, in some nonuniform populations, on the degree of quenched disorder. Hence, in a relatively simple setting this class of models exhibits the qualitative behaviors characteristic of a variety of considerably more complicated models. In addition, we study the microscopic basis of synchronization above threshold and detail the counterintuitive subtleties relating measurements of time averaged frequencies and mean field oscillations. Most notably, we observe a state of suprathreshold partial synchronization in which time-averaged frequency measurements from individual oscillators do not correspond to the frequency of macroscopic oscillations observed in the population

Economic analysis of bedside ultrasonography (US) implementation in an Internal Medicine department

The economic crisis, the growing healthcare demand, and Defensive Medicine wastefulness, strongly recommend the restructuring of the entire medical network. New health technology, such as bedside ultrasonography, might successfully integrate the clinical approach optimizing the use of limited resources, especially in a person-oriented vision of medicine. Bedside ultrasonography is a safe and reliable technique, with worldwide expanding employment in various clinical settings, being considered as "the stethoscope of the 21st century". However, at present, bedside ultrasonography lacks economic analysis. We performed a Cost-Benefit Analysis "ex ante", with a break-even point computing, of bedside ultrasonography implementation in an Internal Medicine department in the mid-term. Number and kind estimation of bedside ultrasonographic studies were obtained by a retrospective study, whose data results were applied to the next 3-year period (foresight study). All 1980 foreseen bedside examinations, with prevailing multiorgan ultrasonographic studies, were considered to calculate direct and indirect costs, while specific and generic revenues were considered only after the first semester. Physician professional training, equipment purchase and working time represented the main fixed and variable cost items. DRG increase/appropriateness, hospitalization stay shortening and reduction of traditional ultrasonography examination requests mainly impacted on calculated revenues. The break-even point, i.e. the volume of activity at which revenues exactly equal total incurred costs, was calculated to be 734 US examinations, corresponding to € 81,998 and the time considered necessary to reach it resulting 406 days. Our economic analysis clearly shows that bedside ultrasonography implementation in clinical daily management of an Internal Medicine department can produce consistent savings, or economic profit according to managerial choices (i.e., considering public or private targets), other than evident medical benefits

Occurrence of Toxic Cyanobacterial Blooms in Rio de la Plata Estuary, Argentina: Field Study and Data Analysis

Water samples were collected during 3 years (2004–2007) at three sampling sites in the Rio de la Plata estuary. Thirteen biological, physical, and chemical parameters were determined on the water samples. The presence of microcystin-LR in the reservoir samples, and also in domestic water samples, was confirmed and quantified. Microcystin-LR concentration ranged between 0.02 and 8.6 μg.L−1. Principal components analysis was used to identify the factors promoting cyanobacteria growth. The proliferation of cyanobacteria was accompanied by the presence of high total and fecal coliforms bacteria (>1500 MNP/100 mL), temperature ≥25°C, and total phosphorus content ≥1.24 mg·L−1. The observed fluctuating patterns of Microcystis aeruginosa, total coliforms, and Microcystin-LR were also described by probabilistic models based on the log-normal and extreme value distributions. The sampling sites were compared in terms of the distribution parameters and the probability of observing high concentrations for Microcystis aeruginosa, total coliforms, and microcystin-LR concentration

Experimental demonstration of coherent transmission over MMF and of the impact of connectors offset

We experimentally demonstrate the possibility of coherent transmission over multimode fiber and discuss its tolerance to offsets in connectors

Flexible distributed Bragg reflectors as optical outcouplers for OLEDs based on a polymeric anode

Top-emitting OLEDs (TOLEDs) represent a promising technology for the development of next-generation flexible and rollable displays, thanks to their improved light outcoupling and their compatibility with opaque substrates. Metal thin films are the most used electrodes for the manufacturing of TOLEDs, but they show poor resistance to mechanical deformation, which compromises the long-term durability of flexible devices. This paper reports the exploitation of a dielectric mirror (DBR) based on seven pairs of TiO2 and SiO2 combined with a polymeric electrode as an alternative to the bottom metal electrode in flexible TOLEDs. The DBR showed a maximum reflectivity of 99.9% at about 550 nm, and a stop-band width of about 200 nm. The reflectivity remained unchanged after bending and treatment with water and solvents. Green TOLED devices were fabricated on top of DBRs, and demonstrated good stability in terms of electro-optical and colorimetric characteristics, according to varying viewing angles. These results demonstrate that the combination of the flexible DBR with the polymeric anode is an interesting strategy for improving the durability of flexible TOLEDs for display applications, implemented on different kinds of free-standing ultra-thin substrates

Short and long term surface chemistry and wetting behaviour of stainless steel with 1D and 2D periodic structures induced by bursts of femtosecond laser pulses

We investigate the short and long term wettability of laser textured stainless steel samples in order to better understand the interplay between surface topography and chemistry. Very different 1D and 2D periodic as well as non-periodic surface patterns were produced by exploiting the extreme flexibility of a setup consisting of five rotating birefringent crystals, which allows generating bursts of up to 32 femtosecond laser pulses with fixed intra-burst delay of 1.5 ps. The change of the surface morphology as a function of the pulse splitting, the burst polarization state and the fluence was systematically studied. The surface topography was characterized by SEM and AFM microscopy. The laser textured samples exhibited, initially, superhydrophilic behaviour which, during exposure to ambient air, turned into superhydrophobic with an exponential growth of the static contact angle. The dynamic contact angle measurements revealed a water adhesive character which was explained by XPS analyses of the surfaces that showed an increase of hydrocarbons and more oxidized metal species with the aging. The characteristic water adhesiveness and superhydrophobicity of laser textured surfaces can be exploited for no loss droplet reversible transportation or harvesting

Double- and multi-femtosecond pulses produced by birefringent crystals for the generation of 2D laser-induced structures on a stainless steel surface

Laser-induced textures have been proven to be excellent solutions for modifying wetting, friction, biocompatibility, and optical properties of solids. The possibility to generate 2D-submicron morphologies by laser processing has been demonstrated recently. Employing double-pulse irradiation, it is possible to control the induced structures and to fabricate novel and more complex 2D-textures. Nevertheless, double-pulse irradiation often implies the use of sophisticated setups for modifying the pulse polarization and temporal profile. Here, we show the generation of homogeneous 2D-LIPSS (laser-induced periodic surface structures) over large areas utilizing a simple array of birefringent crystals. Linearly and circularly polarized pulses were applied, and the optimum process window was defined for both. The results are compared to previous studies, which include a delay line, and the reproducibility between the two techniques is validated. As a result of a systematic study of the process parameters, the obtained morphology was found to depend both on the interplay between fluence and inter-pulse delay, as well as on the number of incident pulses. The obtained structures were characterized via SEM (scanning electron microscopy) and atomic force microscopy. We believe that our results represent a novel approach to surface structuring, primed for introduction in an industrial environment

Light-emitting textiles: Device architectures, working principles, and applications

E-textiles represent an emerging technology aiming toward the development of fabric with augmented functionalities, enabling the integration of displays, sensors, and other electronic components into textiles. Healthcare, protective clothing, fashion, and sports are a few examples application areas of e-textiles. Light-emitting textiles can have different applications: Sensing, fashion, visual communication, light therapy, etc. Light emission can be integrated with textiles in different ways: Fabricating light-emitting fibers and planar light-emitting textiles or employing side-emitting polymer optical fibers (POFs) coupled with light-emitting diodes (LEDs). Different kinds of technology have been investigated: Alternating current electroluminescent devices (ACELs), inorganic and organic LEDs, and light-emitting electrochemical cells (LECs). The different device working principles and architectures are discussed in this review, highlighting the most relevant aspects and the possible approaches for their integration with textiles. Regarding POFs, the methodology to obtain side emissions and the critical aspects for their integration into textiles are discussed in this review. The main applications of light-emitting fabrics are illustrated, demonstrating that LEDs, alone or coupled with POFs, represent the most robust technology. On the other hand, OLEDs (Organic LEDs) are very promising for the future of light-emitting fabrics, but some issues still need to be addressed

Electronic transport, ionic activation energy and trapping phenomena in a polymer-hybrid halide perovskite composite

The exploitation of methylammonium lead iodide perovskite-polymer composites is a promising strategy for the preparation of photoactive thin layers for solar cells. The preparation of these composites is a simple fabrication method with improved moisture stability when compared to that of pristine perovskite films. To deepen the understanding of the charge transport properties of these films, we investigated charge carrier mobility, traps, and ion migration. For this purpose, we applied a combinatory measurement approach that proves how such composites can still retain an ambipolar charge transport nature and the same mobility values of the related perovskite. Furthermore, thermally stimulated current measurements revealed that the polymer influenced the creation of additional defects during film formation without affecting charge mobility. Finally, impedance spectroscopy measurements suggested the addition of starch may hinder ion migration, which would require larger activation energies to move ions in composite films. These results pave the way for new strategies of polymer-assisted perovskite film development