Experimental study on the wear evolution of different PVD coated tools under milling operations of LDX2101 duplex stainless steel

Duplex stainless steels are being used on applications that require, especially, high corrosion resistance and overall good mechanical properties, such as the naval and oil-gas exploration industry. The components employed in these industries are usually obtained by machining, however, these alloys have low machinability when compared to conventional stainless steels. In this work, a study of the wear developed when milling duplex stainless-steel, LDX 2101, is going to be presented and evaluated, employing four types of milling tools with different geometries and coatings, while studying the influence of feed rate and cutting length in the wear of these tools. Tools used have been provided with two and four flutes, as well as three different coatings, namely: TiAlN, TiAlSiN and AlCrN. The cutting behavior of these tools was analyzed; data relative to the cutting forces developed during the process were obtained; and roughness measurements of the machined surfaces were executed. The tools were then submitted to scanning electron microscope (SEM) analysis, enabling the identification of the wear mechanisms that tools were subjected to when machining this material, furthermore, the early stages of these mechanisms were also identified. All this work was done with the goal of relating the machining parameters and cutting force values obtained, identifying, and discussing the wear patterns that were observed in the coating and tools after the milling tests, providing further information on the machining of these alloys. The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00401-5     

Properties of new cork–polymer composites: Advantages and drawbacks as compared with commercially available fibreboard materials

Cork powder (50 wt.%) was mixed with polypropylene (PP) or polyethylene (PE) by pultrusion aiming to prepare cork-based composites. In a further step, samples were produced by compression moulding using the compounded composites. Bending strength, impact resistance, hardness, dimensional stability, thermal and acoustic properties of the developed cork–polymer composites (CPC) were determined and compared with commercially available products namely medium density fibreboard (MDF) and high density fibreboard (HDF). It was found that the CPC have good dimensional stability, lower water uptake, a better acoustic insulation performance and similar behaviour in terms of hardness and fire resistance when compared with both MDF and HDF. However, the mechanical strength is inferior comparing with both commercial materials based on fibres. It was also observed that addition of cork improved the flexural modulus, impact resistance and hardness on the developed CPC. Thus, the herein described CPC materials showed important characteristics to be considered as good candidates to be applied in the design of flooring and construction systems.     

Virtual experimentation on cyanobacterial bloom dynamics and its application to a temperate reservoir (Torrão, Portugal)

The objective of this study was to use artificial neural networks to develop a regression model capable of simulating the complexity of events contributing to the development of cyanobacterial blooms in an important potable water supply located in northern Portugal (Torrão Reservoir). This model was produced with environmental variables collected from the reservoir over a 40‐month sampling period. For development of the model, 10 variables were selected from a total group of 18, all with an equal contribution in the final model. The correlations between the predicted and observed values were high (0.970, 0.912 and 0.908 in the training, verification and test sets, respectively). These variables could be grouped into three categories based on their influence on cyanobacterial abundance. In order of decreasing association, these classes were as follows: (i) oxygen stratification; (ii) conductivity, discharge, and minimum air temperature, water evaporation and solar radiation; and (iii) precipitation, phosphate, ammonia, and pH.     

A review of assistive spatial orientation and navigation technologies for the visually impaired

Universal Access in the Information Society - The overall objective of this work is to review the assistive technologies that have been proposed by researchers in recent years to address the...     

The VILMA intelligent vehicle: an architectural design for cooperative control between driver and automated system

Railway Engineering Science - Intelligent autonomous vehicles have received a great degree of attention in recent years. Although the technology required for these vehicles is relatively advanced,...     

Solid dispersions enhance solubility,dissolution, and permeability of thalidomide

Thalidomide (THD) is a BCS class II drug with renewed and growing therapeutic applicability. Along with the low aqueous solubility, additional poor biopharmaceutical properties of the drug, i.e. chemical instability, high crystallinity, and polymorphism, lead to a slow and variable oral absorption. In this view, we developed solid dispersions (SDs) containing THD dispersed in different self-emulsifying carriers aiming at an enhanced absorption profile for the drug. THD was dispersed in lauroyl macrogol-32 glycerides (Gelucire^® 44/14) and α-tocopherol polyethylene glycol succinate (Kolliphor^® TPGS), in the presence or absence of the precipitation inhibitor polyvinylpyrrolidone K30 (PVP K30), by means of the solvent method. Physicochemical analysis revealed the formation of semicrystalline SDs. X-ray diffraction and infrared spectroscopy analyses suggest that the remaining crystalline fraction of the drug in the SDs did not undergo polymorphic transition. The impact of the solubility-enhancing formulations on the THD biopharmaceutical properties was evaluated by several in vitro techniques. The developed SDs were able to increase the apparent solubility of the drug (up to 2–3x the equilibrium solubility) for a least 4?h. Dissolution experiments (paddle method, 75?rpm) in different pHs showed that around 80% of drug dissolved after 120?min (versus 40% of pure crystalline drug). Additionally, we demonstrated the enhanced solubility obtained via SDs could be translated into increased flux in a parallel artificial membrane permeability assay (PAMPA). In summary, the results demonstrate that SDs could be considered an interesting and unexplored strategy to improve the biopharmaceutical properties of THD, since SDs of this important drug have yet to be reported.     

Analysis of strategies to improve the directionality of square lattice band-edge photonic crystal structures

Recently, photonic crystal band-edge structures have been analyzed in the literature. However, most devices that have been presented so far emit light in different directions. We present a modal analysis (no gain included) of a few schemes to improve the directionality of these devices, i.e., in such a way that light that exits from them will travel mainly in a certain direction, eventually coupling its energy to a wide waveguide.