Build-up-edge (BUE), high-temperature machining and tool wear (TW) are some of the problems associated with difficult-to-machine materials for high-temperature applications, contributing ...significantly to high-cost manufacturing and poor tool life (TL) management. A detailed review of non-traditional machining processes that ease the machinability of INCONEL
, decrease manufacturing costs and suppress assembly complications is thus of paramount significance. Progress taken within the field of INCONEL
non-conventional processes from 2016 to 2023, the most recent solutions found in the industry, and the prospects from researchers have been analysed and presented. In ensuing research, it was quickly noticeable that some techniques are yet to be intensely exploited. Non-conventional INCONEL
machining processes have characteristics that can effectively increase the mechanical properties of the produced components without tool-workpiece contact, posing significant advantages over traditional manufacturing.
Abstract
We studied the properties of the gas of the extended narrow-line region (ENLR) of two Seyfert 2 galaxies: IC 5063 and NGC 7212. We analysed high-resolution spectra to investigate how the ...main properties of this region depend on the gas velocity. We divided the emission lines in velocity bins and we calculated several line ratios. Diagnostic diagrams and suma composite models (photoionization + shocks) show that in both galaxies there might be evidence of shocks significantly contributing in the gas ionization at high |V|, even though photoionization from the active nucleus remains the main ionization mechanism. In IC 5063, the ionization parameter depends on V and its trend might be explained assuming an hollow bi-conical shape for the ENLR, with one of the edges aligned with the galaxy disc. On the other hand, NGC 7212 does not show any kind of dependence. The models show that solar O/H relative abundances reproduce the observed spectra in all the analysed regions. They also revealed an high fragmentation of the gas clouds, suggesting that the complex kinematics observed in these two objects might be caused by interaction between the interstellar medium and high-velocity components, such as jets.
We present the spectral detailed modelling of NGC 4993 – the host galaxy of GW 170817 – and other short gamma-ray burst (SGRB) host galaxies. In order to determine their physical conditions and the ...element abundances, we have gathered spectroscopic and photometric data from the literature. The observation data are sometimes missing, preventing us from fully constraining the model. However, for most of the SGRB hosts the OIII5007/H
β
and NII6548/H
α
line ratios are reported. The analysis of NGC 4993 by a composite model (photoionization+shock) confirms that an active galactic nucleus (AGN), most probably a low-ionization nuclear emission-line region (LINER) or a low-luminosity AGN (LLAGN) is the gas photoionization source. Shock velocities and preshock densities are similar to those found in the narrow line region of AGN. O/H and N/H have solar values. For the other SGRB of the sample, we found that O/H ratios are nearly solar, while N/H covers a much larger range of values at redshifts close to 0.4. In NGC 4993, the relative contribution to the spectral energy distribution of an old stellar population, characterized by a black-body temperature of
T
bb
= 4000 K, with respect to bremsstrahlung is higher by a factor of >100 than in most of the local AGN and starburst (SB) galaxies. For the other SGRB that compose the sample,
T
bb
ranges between 2000 K for SGRB 100206A and 8000 K for SGRB 111117A.
Various functional outcomes after upper blepharoplasty are reported in the literature. We systematically reviewed the literature to assess the objective and subjective functional effects of upper ...blepharoplasty.
After a systematic search of four search engines (Pubmed, Embase, Cinahl and Cochraine), any study on objective and subjective (patient reported) functional outcome after upper blepharoplasty was subjected to a quality assessment for possible inclusion in the review. The intervention was defined as a solitary surgical upper blepharoplasty containing the removal of skin, with or without the removal of a strip of orbicularis oculi muscle and/or upper orbital fat. Eligible studies were randomized controlled trials, controlled trials, cohort studies and case series (n ≥ 10).
A total of 3525 studies were assessed, of which 28 studies were included in this systematic review. Favorable outcomes after an upper blepharoplasty were reported and included enlarged visual field, enhanced quality of life related to fewer headaches and improved vision. Furthermore, sensitivity of the eyelids decreased, with differences in recovery. Outcomes for eyebrow height, astigmatism, contrast sensitivity and eyelid kinematics were not consistent between the studies. No meta-analysis could be performed due to the limited scope of included studies and the great variety in outcomes and blepharoplasty techniques.
Upper blepharoplasty is accompanied by a great variety of beneficial functional outcomes including an increased visual field and improvement in headache- and vision-related quality of life. Further research is needed, especially where results are conflicting (effects on eye dryness and eyebrow height) and/or the data are limited (contrast sensitivity, astigmatism).
Due to Inconel 718’s high mechanical properties, even at higher temperatures, tendency to work-harden, and low thermal conductivity, this alloy is considered hard to machine. The machining of this ...alloy causes high amounts of tool wear, leading to its premature failure. There seems to be a gap in the literature, particularly regarding milling and finishing operations applied to Inconel 718 parts. In the present study, the wear behavior of multilayered PVD HiPIMS (High-power impulse magnetron sputtering)-coated TiN/TiAlN end-mills used for finishing operations on Inconel 718 is evaluated, aiming to establish/expand the understanding of the wear behavior of coated tools when machining these alloys. Different machining parameters, such as cutting speed, cutting length, and feed per tooth, are tested, evaluating the influence of these parameters’ variations on tool wear. The sustained wear was evaluated using SEM (Scanning electron microscope) analysis, characterizing the tools’ wear and identifying the predominant wear mechanisms. The machined surface was also evaluated after each machining test, establishing a relationship between the tools’ wear and production quality. It was noticed that the feed rate parameter exerted the most influence on the tools’ production quality, while the cutting speed mostly impacted the tools’ wear. The main wear mechanisms identified were abrasion, material adhesion, cratering, and adhesive wear. The findings of this study might prove useful for future research conducted on this topic, either optimization studies or studies on the simulation of the milling of Inconel alloys, such as the one presented here.
Composite materials such as Fiber Metal Laminates (FMLs) have attracted the interest of the aerospace and automotive industries due to their high strength to weight ratio, but to use them as ...structures it is necessary to master the manufacturing and wiring techniques of these materials. Therefore, this paper aims to address and summarize the drilling and milling processes in FMLs based on a literature review of papers published from 2000 to 2023. Parameters used in multi-material manufacturing and machining such as drilling and milling, tool geometry, tool coating, lubricants and coolants published by researchers were analyzed, compared and discussed. Machining process parameters related to sustainability were also analyzed. A SWOT analysis was carried out and discussed to identify opportunities for improvement in the machining process. There are opportunities to develop the surface treatment of aluminum alloys, such as testing other combinations than those already used, testing non-traditional surface treatments and manufacturing modes, and developing sustainable techniques during the FML manufacturing process. In the area of tooling, the opportunities are mainly related to coatings for tools and changing machining parameters to achieve an optimum finished part. Finally, to improve the sustainability of the process, it is necessary to test coated drills under cryogenic conditions to reduce the use of lubricants during the machining process.
Nickel-based superalloys, namely INCONEL® variants, have had an increase in applications throughout various industries like aeronautics, automotive and energy power plants. These superalloys can ...withstand high-temperature applications without suffering from creep, making them extremely appealing and suitable for manufactured goods such as jet engines or steam turbines. Nevertheless, INCONEL® alloys are considered difficult-to-cut materials, not only due to their superior material properties but also because of their poor thermal conductivity (k) and severe work hardening, which may lead to premature tool wear (TW) and poor final product finishing. In this regard, it is of paramount importance to optimise the machining parameters, to strengthen the process performance outcomes concerning the quality and cost of the product. The present review aims to systematically summarize and analyse the progress taken within the field of INCONEL® machining sensitively over the past five years, with some exceptions, and present the most recent solutions found in the industry, as well as the prospects from researchers. To accomplish this article, ScienceDirect, Springer, Taylor & Francis, Wiley and ASME have been used as sources of information as a result of great fidelity knowledge. Books from Woodhead Publishing Series, CRC Press and Academic Press have been also used. The main keywords used in searching information were: “Nickel-based superalloys”, “INCONEL® 718”, “INCONEL® 625” “INCONEL® Machining processes” and “Tool-wear mechanisms”. The combined use of these keywords was crucial to filter the huge information currently available about the evolution of INCONEL® machining technologies. As a main contribution to this work, three SWOT analyses are provided on information that is dispersed in several articles. It was found that significant progress in the traditional cutting tool technologies has been made, nonetheless, the machining of INCONEL® 718 and 625 is still considered a great challenge due to the intrinsic characteristics of those Ni-based-superalloys, whose machining promotes high-wear to the tools and coatings used.
Whether the endocrine pancreas exhibits structural features to couple with dietary patterns is not fully explored. Considering the lack of data comparing endocrine pancreas and islet cell ...distribution among different bat species in the same study, we considered this an opportunity to explore the topic, including five species within three different predominant diets. For this, we applied morphometric techniques to compare the islets of frugivorous Artibeus lituratus and Carollia perspicillata, insectivorous Molossus molossus and Myotis nigricans, and nectarivorous Glossophaga soricina bats. Data for islet size, cellularity, and mass were equivalent between frugivorous A. lituratus and nectarivorous G. soricina, which differed from insectivorous bats. The frugivorous C. perspicillata bat exhibited morphometric islet values between A. lituratus and the insectivorous species. A. lituratus and G. soricina but not C. perspicillata bats had higher islet mass than insectivorous species due to larger size, instead of a higher number of islets per area. Insectivorous bats, on the other hand, had a higher proportion of α-cells per islet. These differences in the endocrine pancreas across species with different eating habits indicate the occurrence of species-specific adjustments along the years of evolution, with the demand for α-cells higher in bats with higher protein intake.
Display omitted
•Frugivorous and nectarivorous bats have a higher islet mass than insectivorous bats.•Higher islet mass is due to high cellularity instead of high islet density.•Insectivorous bats exhibit the highest α-cell distribution per islet.
ABSTRACT
We build detailed composite models of photoionization and shock ionization based on the suma code to reproduce emission lines emitted from the Narrow Line Regions (NLR) of Seyfert 2 nuclei. ...The aim of this work is to investigate diagram active galactic nucleus (AGN) positions according to shock parameters, shock effects on the gas temperature and ionization structures and derive a semi-empirical abundance calibration based on emission-line ratios little sensitive to the shock presence. The models were used to reproduce optical (3000 < λ(Å) < 7000) emission line intensities of 244 local ($z \: \lesssim \: 0.4$) Seyfert 2s, whose observational data were selected from Sloan Digital Sky Survey DR7. Our models suggest that shocks in Seyfert 2 nuclei have velocities in the range of 50–300 $\rm km \: s^{-1}$ and imply a narrower metallicity range ($0.6 \: \lesssim \: (Z/Z_{\odot }) \: \lesssim \: 1.6$) than those derived using pure photoionization models. Our results indicate that shock velocity in AGNs cannot be estimated using standard optical line ratio diagrams, based on integrated spectra. Our models predict a different temperature structure and $\rm O^{+}$/O and $\rm O^{2+}$/O fractional abundances throughout the NLR clouds than those derived from pure photoionization models, mainly in shock-dominated objects. This suggests that, in order to minimize the shock effects, the combination of emission-lines emitted by ions with similar intermediate ionization potential could be good metallicity indicators. Finally, we derive two calibrations between the N/O abundance ratio and the N2O2 = log(N iiλ6584/O iiλ3727) and N2 = log(N iiλ6584/H α) indexes which agree with that derived from pure photoionization models.
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