Radial Width Research Articles

Temporal lobe atrophy as a potential predictor of functional outcome in older adults with acute ischemic stroke.

To explore whether temporal lobe atrophy predicts 3-month functional outcome in a population of patients with anterior circulation acute ischemic stroke (AIS) treated with mechanical thrombectomy (MT). We retrospectively selected patients > 65 years from our prospective endovascular stroke registry between June 2013 and August 2018. According to 3-month modified Rankin Scale (mRS), patients were divided in two groups, named good (mRS ≤ 2) and poor (mRS > 2) outcome. Measures of temporal lobe atrophy (i.e., interuncal distance [IUD], medial temporal lobe thickness [mTLT] and radial width of temporal horn [rWTH]) were assessed on pre-treatment CT scan. Cutoff values for good outcome were obtained for IUD, mTLT and rWTH by means of non-parametric ROC curve analysis. Multivariate analysis was performed to identify predictors of outcome. Ordinal shift analysis based on cutoff values was built to evaluate differences in 3-month mRS. Among 340 patients, 130 (38.2%) had good and 210 (61.8%) had poor outcome. We found the following cutoff values for good outcome: < 25mm for IUD, > 15mm for mTLT and < 4mm for rWTH. Lower IUD (OR 0.71; 95% CI 0.63-0.80; p < 0.0001) and rWTH (OR 0.73; 95% CI 0.61-0.87; p < 0.0001) and higher mTLT (OR 1.30; 95% CI 1.14-1.49; p < 0.0001) were independently associated with good outcome. Ordinal shift analysis based on cutoff values revealed significant differences in the rate of good outcome for rWTH (49 vs 27%; p < 0.0001), mTLT (52 vs 21%; p < 0.0001) and IUD (57 vs 17%; p < 0.0001). Assessment of temporal lobe atrophy may predict functional outcome in patients with AIS treated with MT.

Analysis of the coke distribution characteristics in hearth based on blast furnace dissection

The occurrence state and consumption way of coke in blast furnace hearth are of great significance for efficient utilization of blast furnace fuel and low-carbon smelting. In this study, a 2200m3 blast furnace was dissected and core drilling was used to analyze the distribution characteristics of coke in the hearth systematically. It was found that the phases from the hot side of carbon brick to the hearth center were the hot metal channel, CaS agglomerate, slag‑iron-coke bonding phase, scattered coke along the radial direction. A large number of CaS were first found in the hearth with a radial width of 0.8 m. S and K elements were enriched at the interface between slag-coke and iron-coke, which hindered the carburization reaction and renewal mechanism of coke and was not conducive to its efficient utilization. In addition, the ore phase of the coke interface and interior alkali metal salt jointly led to its cracking. The distribution date and utilization ratio of coke in the hearth were clarified. The average coke size was 31.17 mm and the average voidage of the deadman was 40.99%. The mass loss of coke as reducing agent, heat source and carburizing agent during the decline in the furnace were 28.31%, 59.40% and 12.29% respectively.

Numerical Investigation on Mechanism of Swirling Flow of the Prefilming Air-Blast Fuel Injector

Prefilming air-blast atomizers are widely used in modern gas turbine combustors. Due to insufficient awareness of the coupling mechanism of multi-stage swirling flow in gas turbines, there is a lack of effective methods for flow field optimization in combustor. In this study, the effect of some critical parameters on the flow field of a prefilming air-blast atomizer was analyzed with CFD. The parameters include the angle and number of the first swirler blades, the angle of the second swirler blades and the angle of sleeve. Furthermore, the coupling mechanism of two-stage swirling airflows of prefilming air-blast atomizer was discussed. Moreover, the influence of the interaction between two-stage counter swirling airflows on the characteristics of flow field was explained. The results show that with the increase in SNi, the axial length of the primary recirculation zone decreased, while the radial width increased. The starting position of primary recirculation zone (PRZ) moves forward with the increase in SNo. Reducing the sleeve angle β helps to form the primary recirculation zone. The results indicate that it is the transition of tangential velocity of airflow to radial velocity that promotes the formation of the PRZ. These results provide theoretical support for optimization of the flow field in swirl combustor.

Gap-opening Planets Make Dust Rings Wider

As one of the most commonly observed disk substructures, dust rings from high-resolution disk surveys appear to have different radial widths. Recent observations on PDS 70 and AB Aur reveal not only planets in the disk, but also the accompanying wide dust rings. We use three-dimensional dust-and-gas disk simulations to study whether gap-opening planets are responsible for the large ring width in disk observations. We find that gap-opening planets can widen rings of dust trapped at the pressure bump via planetary perturbations, even with the midplane dust-to-gas ratio approaching order unity and with the dust back-reaction accounted for. We show that the planet-related widening effect of dust rings can be quantified using diffusion-advection theory, and we provide a generalized criterion for an equilibrated dust ring width in three-dimensional disk models. We also suggest that the ring width can be estimated using the gas turbulent viscosity α turb, but with cautions about the Schmidt number being greater than order unity.

Potential effects of stellar winds on gas dynamics in debris disks leading to observable belt winds

Context. Gas has been successfully detected in many extrasolar systems around mature stars aged between 10 Myr and ∼1 Gyr that include planetesimal belts. Gas in these mature disks is thought to be released from planetesimals and has been modeled using a viscous disk approach where the gas expands inwards and outwards from the belt where it is produced. Therefore, the gas has so far been assumed to make up the circumstellar disk orbiting the star; however, at low densities, this may not be an adequate assumption, as the gas could be blown out by the stellar wind instead. Aims. In this paper, we aim to explore the timeframe in which a gas disk transitions to such a gas wind and whether this information can be used to determine the stellar wind properties around main sequence stars, which are otherwise difficult to obtain. Methods. We developed an analytical model for A to M stars that can follow the evolution of gas outflows and target the moment of transition between a disk or a wind in order to make a comparison with current observations. The crucial criterion here is the gas density for which gas particles are no longer protected from the impact of stellar wind protons at high velocities and on radial trajectories. Results. We find that: (1) belts with a radial width, ΔR, with gas densities &lt;7 (ΔR/50 au)−1 cm−3, would create a wind rather than a disk, which would explain the recent outflowing gas detection in NO Lup; (2) the properties of this belt wind can be used to measure stellar wind properties such as their densities and velocities; (3) very early-type stars can also form gas winds due to the star’s radiation pressure, instead of a stellar wind; (4) debris disks with low fractional luminosities, f, are more likely to create gas winds, which could be observed with current facilities. Conclusions. Systems containing low gas masses, such as Fomalhaut or TWA 7, or more generally, debris disks with fractional luminosities of f ≲ 10−5(L⋆/L⊙)−0.37 or stellar luminosity ≳20 L⊙ (A0V or earlier) are more likely to create gas outflows (or belt winds) than gas disks. Gas that is observed to be outflowing at high velocity in the young system NO Lup could be an example of such belt winds. Future observing predictions in this wind region should account for the stellar wind in the attempt to detect the gas. The detection of these gas winds is possible with ALMA (CO and CO+ could serve as good wind tracers). This would allow us to constrain the stellar wind properties of main-sequence stars, as these properties are otherwise difficult to measure, since, for example, there are no successful measures around A stars at present.

Global simulations of energetic electron excitation of beta-induced Alfvén eigenmodes

The energetic electron (EE) excitation of beta-induced Alfvén eigenmodes is investigated by using the newly developed global eigenvalue code MAS, which is based on a hybrid model that consists of Landau fluid bulk plasma and drift kinetic EE. Specifically, the bulk plasma kinetic effects such as finite Larmor radius, diamagnetic drifts and Landau dampings, and the EE adiabatic fluid response of convection and non-adiabatic kinetic response of precessional drift resonance are incorporated in the simulations. The global eigenmode equation is solved for e-BAE mode structure and linear dispersion relation in tokamak non-perturbatively. The radial width of e-BAE mode structure becomes narrower as the toroidal mode number increases, which can be explained by the change of Alfvén continuous spectra that interact with kinetic Alfvén waves for corresponding eigenmode formation. The e-BAE growth rate exhibits a non-monotonic variation with toroidal mode number for precessional drift resonance destabilization, while the e-BAE real frequency is close to the continuum accumulation point that almost remains the same. The parametric dependence of e-BAE stability on EE density and that on temperature are analyzed by MAS non-perturbative simulations, which shows that the EE density can affect e-BAE real frequency and thus changes the resonance condition, resulting in e-BAE stabilization in the strong EE drive regime. Further, the EE non-perturbative effect on the symmetry breaking of e-BAE mode structure is reported. The poloidal symmetry breaking characterized by the ‘boomerang’ shape two-dimensional (2D) structure can be greatly enhanced by increasing EE temperature, together with the large radial variation of the poloidal phase angle of dominant principal poloidal harmonic. The radial symmetry breaking of e-BAE mode structure arises when EE density/temperature drive is not symmetric with respect to corresponding rational surface, which can lead to a net volume-averaged value of e-BAE parallel wave number which drives plasma intrinsic rotation. These results are helpful in understanding the e-BAE dynamics observed in recent experiments.

Evaluation of the performance of a high-resolution time-of-flight PET system dedicated to the head and breast according to NEMA NU 2-2012 standard

BackgroundThis study evaluated the physical performance of a positron emission tomography (PET) system dedicated to the head and breast according to the National Electrical Manufacturers Association (NEMA) NU2-2012 standard.MethodsThe spatial resolution, sensitivity, scatter fraction, count rate characteristics, corrections for count losses and randoms, and image quality of the system were determined. All measurements were performed according to the NEMA NU2-2012 acquisition protocols, but image quality was assessed using a brain-sized phantom. Furthermore, scans of the three-dimensional (3D) Hoffmann brain phantom and mini-Derenzo phantom were acquired to allow visual evaluation of the imaging performance for small structures.ResultsThe tangential, radial, and axial full width at half maximum (FWHM) at a 10-mm offset in half the axial field of view were measured as 2.3, 2.5, and 2.9 mm, respectively. The average system sensitivity at the center of the field of view and at a 10-cm radial offset was 7.18 and 8.65 cps/kBq, respectively. The peak noise-equivalent counting rate was 35.2 kcps at 4.8 kBq/ml. The corresponding scatter fraction at the peak noise-equivalent counting rate was 46.8%. The peak true rate and scatter fraction at 8.6 kBq/ml were 127.8 kcps and 54.3%, respectively. The percent contrast value for a 10-mm sphere was approximately 50%. On the 3D Hoffman brain phantom image, the structures of the thin layers composing the phantom were visualized on the sagittal and coronal images. On the mini-Derenzo phantom, each of the 1.6-mm rods was clearly visualized.ConclusionTaken together, these results indicate that the head- and breast-dedicated PET system has high resolution and is well suited for clinical PET imaging.

Betulaceae Familyasına Ait Bazı Türlerin Karşılaştırılmalı Sürgün Anatomisi

Carpinus L. (Gürgen) ve Ostrya Scop. (Kayacık) Betulaceae familyasına bağlı iki cinstir. Bu araştırmada, Türkiye’de doğal yayılış gösteren Carpinus orientalis Mill. (Doğu gürgeni), Carpinus betulus L. (Adi gürgeni) ve Ostrya carpinifolia Scop. (Gürgen yapraklı kayacık) türlerinde sürgünlerin anatomik özellikleri (trahelerin radyal ve teğetsel çapları, 1 mm2’de trahe sayısı, 1 mm’de özışını sayısı, özışını yüksekliği ve özışını genişliği) karşılaştırmalı olarak incelenmiştir. C. orientalis ve C. betulus ikinci yıl sürgününe ait trahelerin radyal ve teğetsel çapları, 1 mm2de trahe sayısı, özışını yüksekliği ve genişliği arasında anlamlı bir fark yoktur. Ancak C. orientalis’in 1 mm’deki özışını sayısı C. betulus’a kıyasla %18 daha fazladır. O. carpinifolia’nın trahe teğet çapı, C. orientalis ve C. betulus’a kıyasla, sırasıyla %37,3 ve %43,5 daha geniştir. Benzer şekilde, O. carpinifolia’nın trahe radyal çapı da diğer iki türe göre sırasıyla %45,1 ve %56,8 daha geniştir. O. carpinifolia’ nın 1 mm2deki trahe sayısı C. orientalis ve C. betulus’a kıyasla sırasıyla %27,6 ve %16,9 daha azdır. O. carpinifolia’nın µm olarak özışını yüksekliği C. orientalis ve C. betulus’a kıyasla sırasıyla %71,5 ve %69 daha düşüktür. İncelenen üç türün özışını genişlikleri (µm ve hücre sayısı olarak) ve özışını yükseklilerinde (hücre sayısı olarak) anlamlı fark bulunmamıştır.

Instability and symmetry breaking of surfactant films over an air bubble

We examine the asymmetric flows of aqueous surfactant films over an air bubble. A thin film is formed by raising an equilibrated air bubble through an aqueous solution of Triton X-100 (0.01 mM, below critical micelle concentration). Due to the advection generated by the squeezing motion, the initially uniformly distributed surfactants redistribute and, thus, generate an axisymmetric surface tension gradient that drives a Marangoni flow. The external forcing of raising the bubble also creates an axisymmetric dimpled film with a radial thickness variation that reaches its minimum at the rim of the dimple. The curvature in the film thickness generates an axisymmetric capillary pressure driven flow. When the apex of the bubble has penetrated the initially flat air-solution interface, the rising bubble is stopped and the resulting flow demonstrates symmetry breaking both in the experiment and in the parameter matched numerical simulation. Linear stability analysis reveals the mechanism behind the disturbance growth. It is found that the most dangerous azimuthal wavenumber scales linearly with the ratio of the rim radius to the radial width of significant radial pressure and surface tension gradients after stopping the bubble. Finally, we compare this instability to the previously studied surfactant spreading induced fingering phenomenon (Warner, Craster &amp; Matar, Phys. Fluids, vol. 16, issue 8, 2004, pp. 2933–2951).

The Geometry of the G29-38 White Dwarf Dust Disk from Radiative Transfer Modeling

Many white dwarfs host disks of dust produced by disintegrating planetesimals and revealed by infrared excesses. The disk around G29-38 was the first to be discovered and is now well-observed, yet we lack a cohesive picture of its geometry and dust properties. Here we model the G29-38 disk for the first time using radiative transfer calculations that account for radial and vertical temperature and optical depth gradients. We arrive at a set of models that can match the available infrared measurements well, although they overpredict the width of the 10 μm silicate feature. The resulting set of models has a disk inner edge located at 92–100 R WD (where R WD is the white dwarf radius). This is farther from the star than inferred by previous modeling efforts due to the presence of a directly illuminated front edge to the disk. The radial width of the disk is narrow (≤10 R WD); such a feature could be explained by inefficient spreading or the proximity of the tidal disruption radius to the sublimation radius. The models have a half-opening angle of ≥1.°4. Such structure would be in strong contradiction with the commonly employed flat-disk model analogous to the rings of Saturn, and in line with the vertical structure of main-sequence debris disks. Our results are consistent with the idea that disks are collisionally active and continuously fed with new material, rather than evolving passively after the disintegration of a single planetesimal.

Automatic estimation of annual ring profiles in Norway spruce timber boards using optical scanning and deep learning

In softwood species, annual ring width correlates with various timber characteristics, including the density and modulus of elasticity along with bending and tensile strengths. Knowledge of annual ring profiles may contribute to more accurate machine strength grading of sawn timber. This paper proposes a fast and accurate method for automatic estimation of ring profiles along timber boards on the basis of optical scanning. The method utilizes two 1D convolutional neural networks to determine the pith location and detect the surface annual rings at multiple cross-sections along the scanned board. The automatically extracted rings and pith information can then be used to estimate the annual ring profile at each cross-section. The proposed method was validated on a large number of board cross-sections for which the pith locations and radial ring width profiles had been determined manually. The paper also investigates the potential of using the automatically estimated average ring width as an indicating property in machine strength grading of sawn timber. The results indicated that combining the automatically estimated ring width with other prediction variables can improve the accuracy of bending and tensile strength predictions, especially when the grading is based only on information extracted from optical and laser scanning data.

Linking wood density records of common beech (Fagus sylvatica L.) with temperature and precipitation variability from a temperate lowland site.

European lowland beech stands are under pressure by current climate change and increased drought spells. Climate sensitivity of trees is most commonly studied by examining tree-ring width records and wood density-based time series, yet the potential of the latter is underexplored for hardwoods and beech (Fagus sylvatica L.) in particular. Here, we investigate how variability in radial growth, Maximum Latewood Density (MXD) and intra-annual wood density records in lowland beech are related to monthly and daily temperature (T) and precipitation (P) records, as well as the Standardized Precipitation Evapotranspiration Index (SPEI), during the past 50 years. 45 increment cores were collected from healthy (co-) dominant beech trees in Flanders (northern Belgium). We used X-ray micro-Computed Tomography (XµCT) to obtain wood density and tree-ring width series. By dividing every tree-ring into 4 sectors of equal radial width, we also assessed climatic forcings on intra-annual wood density variability (meanQi, i = 1:4). Water availability (SPEI) is the most important factor limiting radial growth, whereas MXD is correlated with summer temperature (period May-July, r = 0.334). Scanning resolution (110, 60, 20 µm) proves to be an important parameter when interpreting MXD values. We found that to quantify climate signals at the end of the growing season, density values should be representative for a relatively large part of the latewood. Our results also suggest that a sector approach is useful by showing climatic influences during the entire growing season. Wood density at the beginning of the growing season is mainly influenced by water availability (meanQ1∼SPEI, r = 0.416), whereas towards the end of the growing season only significant correlations with temperature were observed (meanQ4∼T, r = 0.347). We recommend to further explore MXD values for hardwood trees in lowland Europe.

Numerical study of m = 2/n = 1 neoclassical tearing mode stabilized by the Ohkawa-mechanism-dominated current drive of electron cyclotron waves

This paper reports a numerical study of the 2/1 neoclassical tearing mode (NTM) stabilized by the Ohkawa-mechanism-dominated current drive (OKCD) of electron cyclotron (EC) waves, and the results are compared with those of the traditional Fisch–Boozer mechanism dominated EC current drive (ECCD). The peak values, radial positions and radial widths of the driven current profiles by EC waves are passed to the modified Rutherford equation to study the effect of OKCD/ECCD on the 2/1 NTM. Well-localized current density profiles and large driven current can be achieved for 2/1 NTM stabilization in a low-aspect-ratio tokamak (R/a ∼ 2.7) by using OKCD. The optimal minimum EC powers are calculated for both OKCD and ECCD to fully stabilize the 2/1 NTM. We compare our results with those of ECCD to stabilize the 2/1 NTM, when the choices of magnetic field strength and gyrotron frequency are such that off-axis deposition on the high-field side is not practical to generate localized current effectively, so that the electron trapping effect is large and important. In this paper, we show that it is better to use lower gyrotron frequencies optimized for the Ohkawa mechanism to obtain a higher current drive efficiency for 2/1 NTM stabilization.

An enhanced artificial bee colony algorithm using radial bases function neural networks for color image segmentation

The aim of segmentation process is to partition the image into homogeneous regions or objects. The proposed segmentation algorithms using adaptive feature weighting to distinguish the significance of various features. To extract effective feature extraction could be used for establishing regions in region based image segmentation. The main goal of this exploration work is to segment objects that separating the foreground and background of the color images. The segmentation for color images is focused on the Enhanced Artificial Bee Colony segmentation algorithm that utilizes the Radial Basis Function (EABCRBF) neural network algorithm. This work arranges RBF neural networks to predict the end limits of the segmentation, which are formed from the artificial bee colony province made in the image histogram topography. The radial basis function initial parameters, for instance, centers and widths are automatically set upon the histogram peaks and minima. The proposed EABCRBF strategy is compared with two existing techniques of Artificial Bee Colony (ABC) and Fuzzy C-Means (FCM). The EABCRBF method gives great outcomes for color image segmentation as it extracts additional information from color images. The experimentation results are shown through Mat Lab R2013a.

Coupled effect of spatio-temporal variation of Laguerre–Gaussian laser pulse on electron acceleration in magneto-plasma

In this work, the acceleration of electrons via incidence of a Laguerre–Gaussian laser pulse in a plasma medium with relativistic non-linearity in the presence of a uniform external magnetic field along the direction of propagation has been presented. The moment theory approach has been used to obtain the two non-linear second-order differential equations, which have been further solved numerically to determine the variation in the radial and temporal width of the laser pulse in the plasma medium. The propagation of the laser pulse in the plasma medium excites the electron plasma wave, which acts as a wakefield for electron acceleration. The effect of radial and temporal variation on electron acceleration has also been investigated. Furthermore, the spatio-temporal variation and energy gain have been studied for different Laguerre modes of lasers, their intensities, and plasma densities.

Tree-ring anatomy of Pinus cembra trees opens new avenues for climate reconstructions in the European Alps

Tree rings form the backbone of high-resolution palaeoclimatology and represent one of the most frequently used proxy to reconstruct climate variability of the Common Era. In the European Alps, reconstructions were often based on tree-ring width (TRW) and maximum latewood density (MXD) series, with a focus on European larch. By contrast, only a very limited number of dendroclimatic studies exists for long-lived, multi-centennial Pinus cembra, despite the widespread occurrence of the species at treeline sites across the European Alps. This lack of reconstructions can be ascribed to the difficulties encountered in past studies in extracting a robust climate signal from TRW and MXD chronologies. In this study, we tested various wood anatomical parameters from P. cembra as proxies for the reconstruction of past air temperatures. To this end, we measured anatomical cell parameters and TRW of old-growth trees from the God da Tamangur forest stand, known for being the highest pure, and continuous P. cembra forest in Europe. We demonstrate that several wood anatomical parameters allow robust reconstruction of past temperature variability at annual to multidecadal timescales. Best results are obtained with maximum latewood radial cell wall thickness (CWTrad) measured at 40 μm radial band width. Over the 1920–2017 period, the CWTrad chronology explains 62 % and >80 % of interannual and decadal variability of air temperatures during a time window corresponding roughly with the growing season. These values exceed those found in past work on P. cembra and even exceed the values reported for MXD chronologies built with L. decidua and hitherto considered the gold standard for dendroclimatic reconstructions in the European Alps. The wood anatomical analysis of P. cembra records therefore unveils a dormant potential and opens new avenues for a species that has been considered unsuitable for climate reconstructions so far.

Ulna’nın Proksimal Bölümünün Anatomik Yapısı

Amaç: Ulna’nın proksimal bölümü'nün şekli, kırıkların stabilizasyonunu ve cerrahi sonrası fonksiyonların rehabilitasyonunu etkileyen unsurlardan birisidir. Redüksiyon sırasında normal anatomik yapılanma sağlanamaz ise bu durum eklemin çıkıklarına, artritine ve fonksiyon kaybına neden olabilir. Redüksiyonun tam olarak gerçekleştirilemediği ufak parçalı kırıklarda ise uygun bir plak yardımı ile anatomik yapılanma desteklenebilir. Plak kullanımının gerektiği durumlarda ise ulna’nın proksimal bölümü yapısının detaylı bilinmesi önemlidir.Materyal ve metod: Bu çalışma, Necmettin Erbakan Üniversitesi, Meram Tıp Fakültesi, Anatomi Anabilim Dalı’na ait kemik koleksiyonundaki 62 (cinsiyetleri belirsiz, 26 sağ ve 36 sol ulna) adet ulna üzerinde gerçekleştirildi. Çalışmamızda ulna'nın proksimal bölümü'ne ait uzunluk ve genişlik ölçümleri ile birlikte açı ölçümleri gerçekleştirilmiştir.Bulgular: Çalışmamızda toplam ulna uzunluğu (UU) ortalama 24.59±2.00 cm olarak belirlenmiştir. Inc. radialis yükseklik (IRY) ve genişlik (IRG) ölçümleri tüm ulna’larda ortalama olarak sırasıyla 9.69±1.64 mm ve 15.22±2.18 mm olarak belirlenmiştir. Inc. trochlearis derinliğinin (ITD) ise 7.30 ile 13.70 mm (ortalama 10.15 mm) arasında değişkenlik gösterdiği belirlenmiştir. Tüm ulna’larda ortalama ulna’nın proksimal bölümü torsiyon açısı (PUTA), varus açısı (VA), artiküler açı (AA), ulna’nın proksimal bölümü dorsal açısı (PUDA), tüberkül açısı (TA), olecranon-diyafiz açısı (ODA) sırasıyla 13.40±1.230, 9.20±1.850, 20.37±1.020, 5.85±2.210, 18.99±0.830, 15.49±3.100 olarak belirlenmiştir.Sonuç: Bireysel farklılıkların göz önüne alınarak tasarlandığı implant ve protezler dirsek eklemindeki uyumun başarı oranını arttırmakta ve eklemin fonksiyonunu düzgün olarak yerine getirilmesini sağlamak-tadır.

Modelling of Metal Removal Rate in Copper Alloy Milling Using MATLAB

The copper found in Earth’s soil ranks fourth in abundance among structural metals. Copper alloys are composed of copper and other elements. Most commonly, these alloys are used in aerospace, medical, and energy applications, but they are also used in many other areas. The amount of the stabilizing agents and the temperature determine which phase copper alloys exist in, including α, α + β, and β. The temperature in the cutting zone is one of the most important factors to control when machining copper alloys. Copper alloys have low thermal conductivity and high heat capacity, meaning that they have low heat conduction from the cutting zone, which leads to the built-up heat in the cutting edge. As the workpiece and cutting tool moves at different speeds, the temperature is strongly affected by the cutting speed. The physical and chemical properties of tool wear progression have been used in several studies and research projects to model tool life and metal removal as a result of this fact. The focus of this article is on establishing a model connecting cutting parameters and measured responses in terms of tool life, using the design of experiments and metamodeling to establish a model that can be used to predict tool life from milling experiments. In order to secure reliable machining operations, these models were designed for customer recommendation and cutting data optimization. The study focused on copper alloys 6Al-4V, the most common being α + β alloy. In conclusion, the two models developed in this study are able to predict the tool life based on the cutting speed and radial width of cuts. As long as certain parameters are met, the models will ensure the highest possible metal removal rate.

Kinematics of luminous blue variables in the Large Magellanic Cloud

ABSTRACT We study the kinematics of luminous blue variables (LBVs) in the Large Magellanic Cloud (LMC). Using high-resolution spectra, we measure the systemic radial velocities for a sample of 16 LBVs and LBV candidates. In order to measure the net motion of LBVs compared to their local environments, we subtract the projected line-of-sight velocity at the same location derived from the rotation curve model of the LMC. Using nebular and wind emission lines, we infer a velocity dispersion for LBVs of $40.0^{+9.9}_{-6.6}$ km s−1. To put LBVs in context with other evolved massive stars, we compare this to red supergiants (RSGs) in the LMC, which have a significantly smaller velocity dispersion of $16.5^{+0.4}_{-0.6}$ km s−1. Moreover, 33 per cent of LBVs have radial velocities of more than 25 km s−1, while only 9 per cent of RSG have such high velocities. This suggests that LBVs include more runaways than the population of stars that evolves to become RSGs, indicating that LBVs are preferentially kicked by a companion’s supernova explosion as compared to other evolved massive stars. Our investigation reveals other interesting clues about LBVs in the LMC as well. We find that radial velocities and widths of emission lines for each target remain constant over several epochs, whereas measured absorption lines exhibit highly variable radial velocities for R110, R81, S Dor, Sk-69°142a, and Sk-69°279. These five LBVs probably have a binary companion. Additionally, we find that Sk-69°142a experienced its second outburst in 2019 September, shifting its status from candidate to confirmed LBV.

Delivery of Gas onto the Circumplanetary Disk of Giant Planets: Planetary-mass Dependence of the Source Region of Accreting Gas and Mass Accretion Rate

Gas accretion onto the circumplanetary disks and the source region of accreting gas are important to reveal dust accretion that leads to satellite formation around giant planets. We performed local three-dimensional high-resolution hydrodynamic simulations of an isothermal and inviscid gas flow around a planet to investigate the planetary-mass dependence of the gas accretion bandwidth and gas accretion rate onto circumplanetary disks. We examined cases with various planetary masses corresponding to M p = 0.05–1M Jup at 5.2 au, where M Jup is the current Jovian mass. We found that the radial width of the gas accretion band is proportional to for the low-mass regime with M p ≲ 0.2M Jup while it is proportional to M p for the high-mass regime with M p ≳ 0.2M Jup. We found that the ratio of the mass accretion rate onto the circumplanetary disk to that into the Hill sphere is about 0.4 regardless of the planetary mass for the cases we examined. Combining our results with the gap model obtained from global hydrodynamic simulations, we derive a semi-analytical formula of mass accretion rate onto circumplanetary disks. We found that the mass dependence of our three-dimensional accretion rates is the same as the previously obtained two-dimensional case, although the qualitative behavior of accretion flow onto the circumplanetary disk is quite different between the two cases.