Distribution Of Axes Research Articles

Using Misorientation and Weighted Burgers Vector Statistics to Understand Intragranular Boundary Development and Grain Boundary Formation at High Temperatures

AbstractDuring plastic deformation, strain weakening can be achieved, in part, via strain energy reduction associated with intragranular boundary development and grain boundary formation. Grain boundaries (in 2D) are segments between triple junctions, that connect to encircle grains; every boundary segment in the encircling loop has a high (>10°) misorientation angle. Intragranular boundaries terminate within grains or dissect grains, usually containing boundary segments with a low (<10°) misorientation angle. We analyze electron backscatter diffraction (EBSD) data from ice deformed at −30°C ( 0.9). Misorientation and weighted Burgers vector (WBV) statistics are calculated along planar intragranular boundaries. Misorientation angles change markedly along each intragranular boundary, linking low‐ (<10°) and high‐angle (10–38°) segments that exhibit distinct misorientation axes and WBV directions. We suggest that these boundaries might be produced by the growth and intersection of individual intragranular boundary segments comprising dislocations with distinct slip systems. There is a fundamental difference between misorientation axis distributions of intragranular boundaries (misorientation axes mostly confined to ice basal plane) and grain boundaries (no preferred misorientation axis). These observations suggest during progressive subgrain rotation, intragranular boundaries remain crystallographically controlled up to large misorientation angles (>>10°). In contrast, the apparent lack of crystallographic control for grain boundaries suggests misorientation axes become randomized, likely due to the activation of additional mechanisms (such as grain boundary sliding) after grain boundary formation, linking boundary segments to encircle a grain. Our findings on ice intragranular boundary development and grain boundary formation may apply more broadly to other rock‐forming minerals (e.g., olivine, quartz).

Combined effects of disc winds and turbulence-driven accretion on planet populations

ABSTRACT Recent surveys show that protoplanetary discs have lower levels of turbulence than expected based on their observed accretion rates. A viable solution to this is that magnetized disc winds dominate angular momentum transport. This has several important implications for planet formation processes. We compute the physical and chemical evolution of discs and the formation and migration of planets under the combined effects of angular momentum transport by turbulent viscosity and disc winds. We take into account the critical role of planet traps to limit Type I migration in all of these models and compute thousands of planet evolution tracks for single planets drawn from a distribution of initial disc properties and turbulence strengths. We do not consider multiplanet models nor include N-body planet–planet interactions. Within this physical framework we find that populations with a constant value disc turbulence and winds strength produce mass–semimajor axis distributions in the M–a diagram with insufficient scatter to compare reasonably with observations. However, populations produced as a consequence of sampling discs with a distribution of the relative strengths of disc turbulence and winds fit much better. Such models give rise to a substantial super Earth population at orbital radii 0.03–2 au, as well as a clear separation between the produced hot Jupiter and warm Jupiter populations. Additionally, this model results in a good comparison with the exoplanetary mass–radius distribution in the M–R diagram after post-disc atmospheric photoevaporation is accounted for.

Comparative study on the high frequency performances of the easy-plane FeNi@SiO2 powder soft magnetic composite

In this work, an easy-plane FeNi@SiO2 powder soft magnetic composite (SMC) was imitated and fabricated and its high frequency magnetic properties were comparatively investigated with a non-easy-plane composite. Due to the planar distribution of easy magnetization axes, the easy-plane composite exhibits a constant permeability of 38 up to 100 MHz. Moreover, the easy-plane SMC exhibits a lower core loss at higher frequencies. Loss separated results show that the hysteresis loss plays a dominant loss component in the composite, rather than dominant excess loss in the non-easy-plane powder composite. These results indicate that, compared with non-easy-plane powder composite, the easy-plane powder composites exhibit comprehensive advantages of higher permeability, wider effective operating frequencies and lower loss, which suggest that the use of easy-plane ferromagnetic powder is a promising and efficient measure to develop a new generation of soft magnetic composites for higher frequency application.

Radiative shock oscillation model for the long-term flares of Sgr A*

ABSTRACT We examine time-dependent 2D relativistic radiation magnetohydrodynamic (MHD) flows to develop the shock oscillation model for the long-term flares of Sagittarius A* (Sgr A*). Adopting modified flow parameters in addition to the previous studies, we confirm quasi-periodic flares with periods of ∼5 and 10 d that are compatible with observations by Chandra, Swift, and XMM–Newton monitoring of Sgr A*. Using a simplified two-temperature model of ions and electrons, we find that the flare due to synchrotron emission lags that of bremsstrahlung emission by 1–2 h that are qualitatively comparable to the time lags of 1–5 h reported in several simultaneous observations of radio and X-ray variability in Sgr A*. The synchrotron emission is confined in a core region of 3Rg size with the strong magnetic field, while the bremsstrahlung emission mainly originates in a distant region of 10–20Rg behind the oscillating shock, where Rg is the Schwarzschild radius. The time lag is estimated as the transit time of the acoustic wave between the above two regions. The time-averaged distribution of radiation shows a strong anisotropic nature along the rotational axis but isotropic distribution in the radial direction. A high-velocity jet with ∼0.6c along the rotational axis is intermittently found in a narrow funnel region with a collimation angle ∼15°. The shock oscillating model explains well the flaring rate and the time lag between radio and X-ray emissions for the long-term flares of Sgr A*.

Competing magnetic states and M–H loop splitting in core–shell NiO nanoparticles

Magnetic relaxation in a nanoparticles system depends on the intra-particle interactions, reversal mechanism, the anisotropy field, easy axis distribution, particle volume, lattice defects, surface defects, materials composite, etc. Here we report the competing magnetic states between superparamagnetic blocking and Néel transition states in 14 nm core–shell NiO nanoparticles. A crossover temperature of 50 K was observed for both these states from the zero field cooled/field cooled magnetization curves taken at different fields. At crossover temperature, an interesting M–H loop splitting is observed which is attributed to the slow spin relaxation. This anomalous M–H loop splitting behaviour was found to be particle size dependent and suppressed for diameters above and below 14 nm which indicates a critical size for these competing magnetic states. Additional neutron diffraction experiments confirmed this observation. This experimental study provides a new insight for the understanding of intra-particle interactions in fine antiferromagnetic nanoparticles and obtained results are an important step towards deeper understanding of the competing/non-competing modes between superparamagnetic blocked and Néel transition states.

Experimental study on trajectory flame length and axial temperature distribution of inclined turbulent jet flames

Uncontrollable jet fires are a typical disaster caused in process industries involving hazardous materials. Jet fires are also great safety hazards in the process of pipeline transportation. With the development of pipeline transportation, pipe network leakage events often do not occur in simple scenarios, but in more complex situations, such as in inclined jet fires. There are few studies on the physical characteristics of inclined jet flames in specific environments, which is of great significance for safety protection. In this work, experiments on turbulent diffusion jet flames in different inclined states (−90°to 90°) with nozzle diameters ranging between 2 and 6 mm were carried out. The jet flame length and temperature distribution of the central axis of the flame were analysed. In the present study, a theoretical model is derived to incorporate the effect of the jet inclined angle on the flame length. The experimental results show that both the flame length and the temperature of the central axis of the flame decrease with a decrease of the angle. Finally, the correction angle is introduced into the classical model, and a new dimensionless correlation is established, which is in good agreement with the current and other authors’ experimental results.

Decentralised Funding Activities of the Leader Local Action Groups of the North Hungarian Region from a Governancepoint of View

Abstract Our article investigates the utilisation of EU support from the EFARD Axes 3 and 4 in the 2007–2013 period in North Hungary, with a special emphasis on the role of the LEADER local action groups (LAGs) and their forms of governance. A brief study ofthe results of the 2014–2020 period was also included. The distribution of resources was examined by a spatial inequality indicator, the Gini coefficient. Additionally, a questionnaire survey was conducted to explore the level and forms of governance in the case of LAGs. Our research results suggest that the distribution of Axis 3 resources within local action groups shows greater inequality in fewer LAGs. The Axis 4 denotes higher inequality. The level of governance of LAGs is relatively low as it is achieved through strong local leaders. This may explain high spatial inequalities of fund distribution.

On the flow of liquid crystals through 90° bends

During the processing of nematic soft solids through process flow elements (pipe bends, elbows, etc.), the constitutive behavior makes its presence felt via processing (with rheology driven effects increasing pressure drop) and the final product microstructure. This paper explores the flow and microstructure configurations of nematic liquid crystals in a pressure driven flow through 90° pipe bends with different types of wall anchoring. The governing equations of the Leslie–Ericksen theory are solved numerically in a newly developed OpenFOAM solver. We show that the bend curvature deforms the nematic axis distribution; the distortion can be driven either by elastic or hydrodynamic effects. The interaction between the nematic microstructure and flow field generates non-zero normal stresses (in the radial, azimuthal, and streamwise directions), which produce a secondary flow and increase pressure losses. The strength of the secondary flow depends on the type of wall anchoring and Ericksen number; in configurations with homeotropic anchoring, decreasing the Ericksen number increases the relative strength of the secondary flow (with respect to the mean flow velocity). Conversely, homogeneous (planar) anchoring reduces normal stresses, thus weakening the secondary flow strength. We show that as the fluid enters/leaves the bend, there is a perturbation in the transverse velocity caused by streamwise stress gradients. The perturbation magnitude depends on material properties and can be of different values at the bend exit and entrance. Finally, we show that the spatial development of the nematic field downstream of the bend exit is controlled by both material properties and the Ericksen number.

Optical isolation via direction-dependent soliton routing in birefringent soft matter.

We introduce optical isolation based on reorientational solitary waves in nonuniformly oriented uniaxial soft matter, namely nematic liquid crystals. A longitudinally nonsymmetric angular distribution of the optic axis provides the system with direction-dependent routing, resulting in an all-optical diode owing to input-side sensitive steering. Numerical experiments demonstrate the phenomenon and its effectiveness in realistic samples.

The Great Planetary Heist: theft and capture in star-forming regions

ABSTRACT Gravitational interactions in star-forming regions are capable of disrupting and destroying planetary systems, as well as creating new ones. In particular, a planet can be stolen, where it is directly exchanged between passing stars during an interaction; or captured, where a planet is first ejected from its birth system and is free-floating for a period of time, before being captured by a passing star. We perform sets of direct N-body simulations of young, substructured star-forming regions, and follow their evolution for 10 Myr in order to determine how many planets are stolen and captured, and their respective orbital properties. We show that in high-density star-forming regions, stolen and captured planets have distinct properties. The semimajor axis distribution of captured planets is significantly skewed to wider orbits compared to the semimajor axis distribution of stolen planets and planets that are still orbiting their parent star (preserved planets). However, the eccentricity and inclination distributions of captured and stolen planets are similar, but in turn very different to the inclination and eccentricity distributions of preserved planets. In low-density star-forming regions these differences are not as distinct but could still, in principle, be used to determine whether observed exoplanets have likely formed in situ or have been stolen or captured. We find that the initial degree of spatial and kinematic substructure in a star-forming region is as important a factor as the stellar density in determining whether a planetary system will be altered, disrupted, captured, or stolen.

Posture Estimation Using Surface Electromyography during Wheelchair Hand-Rim Operations.

This study examined competitive wheelchairs that facilitate sports participation. They can be moved straight ahead using only one arm. Our designed and developed competitive wheel-chairs have a dual hand-rim system. Their two hand-rims, attached to a drive wheel on one side, can be operated simultaneously for straight-ahead movement. Specifically, based on integrated electromyography (iEMG) data calculated from surface electromyography (sEMG), we examined the wheelchair loading characteristics, posture estimation, and effects on body posture during one-arm propulsion movement. The first experiment yielded insights into arm and shoulder-joint muscle activation from iEMG results obtained for two-hand propulsion and dual hand-rim system propulsion. Results suggest that muscle activation of one arm can produce equal propulsive force to that produced by two arms. The second experiment estimated the movement posture from iEMG during one-arm wheelchair propulsion. The external oblique abdominis is particularly important for one-arm wheelchair propulsion. The iEMG posture estimation validity was verified based on changes in the user body axis and seat pressure distribution. In conclusion, as confirmed by iEMG, which is useful to estimate posture during movement, one-arm wheelchair use requires different muscle activation sites and posture than when using two arms.

Discrepancies between point process models and environmental envelopes identify the niche centroid – geography configuration

Contrasting outcomes of statistical modelling methods for the same data may represent critical pieces of information about the biological process. Ecological niche and species distribution modelling are notorious for their keenness on algorithm testing although differences between method outcomes are seldom used to gain biological insight. Here we use the differences and similarities between point process models (PPMs) and minimum volume ellipsoids (MVEs) to help identify the configuration of species’ climatic niches in relation to geographic space and species’ interactions. Poisson PPMs represent the abundance of points in an euclidean plane as a function of spatially defined covariates, while MVEs are used to estimate the (niche) centroid and represent similarity with its centroid via Mahalanobis distance. The niche centroid is receiving increasing attention due to its simplicity and ability to capture complex demographic processes such as species’ abundance. MVEs’ simplicity makes them sensitive to deviations from symmetry in the statistical distribution of environmental axes, or the lack of a defined centroid in geographic space. Using synthetic and real species we test the ability of PPMs and MVEs to characterise niche centroids in relation to each other and to the statistical properties of the environment. We also study a scenario in which non-linear responses and biological interactions define a species’ fundamental niche and realised distribution respectively. MVEs were less precise but estimated useful centroids more frequently than PPMs. When centroids clearly existed in geographic and environmental spaces, PPMs’ estimated centroids that were closer to the truth. MVEs’ ability to estimate a similarity surface, unlike PPMs, depends on the correct estimation of the centroid. We suggest then that contrasting similarity surfaces estimated by both methods indicate the absence of the centroid in geographic space.

Polymer-Dispersed Cholesteric Liquid Crystal under Homeotropic Anchoring: Electrically Induced Structures with λ1/2-Disclination.

Orientational structures of polymer-dispersed cholesteric liquid crystal under homeotropic anchoring and their transformations under the action of an electric field are studied. The switching of cholesteric droplets between different topological states are experimentally and theoretically demonstrated. Structures with -disclination are found and considered. These structures are formed during the transformation of a twisted toroidal configuration induced by a decrease in the electric field when a relative chiral parameter . The transformation of the initial structure with a bipolar distribution of the helix axis into a twisted toroidal configuration and then into a structure with -disclination is investigated in detail. The behavior of these structures under the influence of an external electric field, as well as the appearance of structures with -disclination, are studied. Obtained results are promising for the development of optical materials with programmable properties.

Automated Charting of the Visual Space of Housefly Compound Eyes.

This paper describes the automatic measurement of the spatial organization of the visual axes of insect compound eyes, which consist of several thousands of visual units called ommatidia. Each ommatidium samples the optical information from a small solid angle, with an approximate Gaussian-distributed sensitivity (half-width on the order of 1˚) centered around a visual axis. Together, the ommatidia gather the visual information from a nearly panoramic field of view. The spatial distribution of the visual axes thus determines the eye's spatial resolution. Knowledge of the optical organization of a compound eye and its visual acuity is crucial for quantitative studies of neural processing of the visual information. Here we present an automated procedure for mapping a compound eye's visual axes, using an intrinsic, in vivo optical phenomenon, the pseudopupil, and the pupil mechanism of the photoreceptor cells. We outline the optomechanical setup for scanning insect eyes and use experimental results obtained from a housefly, Musca domestica, to illustrate the steps in the measurement procedure.

Active Slip Mode Analysis of an Additively Manufactured Ti-6Al-4V Alloy via In-Grain Misorientation Axis Distribution

Selective laser-melted (SLM) Ti-6Al-4V alloy was quasi-statically compressed in the transverse and longitudinal directions at a strain rate of 1 × 10−3 s−1 at room temperature. The twinning, in-grain misorientation axis (IGMA) distribution and active slip modes of individual grains in the deformed SLM Ti-6Al-4V alloy were studied in detail via transmission Kikuchi diffraction (TKD) and transmission electron microscopy (TEM). The α’/α phase was textured with the c-axis oriented either at ~45° or perpendicular to the building direction (BD). A combined analysis of the IGMA distribution and Schmid factor revealed that the prismatic <a> slip or pyramidal slip was easily activated in the soft grains with their c-axes perpendicular to the BD (or the loading direction) in the longitudinal compressed sample, while slip was hardly activated in the transverse compressed sample due to the lack of soft grains. Prismatic <a> slip with IGMA around <0001> Taylor axis also occurred in {10–11} twins. The observations revealed that the prismatic <a> slip played a key role in accommodating the external strain and, thus, well explained the anisotropy of mechanical properties in the SLM Ti-6Al-4V alloy.

Deformation mechanisms and characteristics of the meta-BIFs from an early Proterozoic shear system of the Southern Granulite Terrane (SGT), India

We studied three samples of Banded Iron Formation (BIF) rocks from Southern Granulite Terrane (SGT) of India, which was metamorphosed at high-pressure granulite facies and exhumed from 40 to 50 km depth. We examined the microstructure, texture, and deformation mechanisms of the primary minerals (quartz, magnetite, and hematite). Microstructures, variations in size and shape of quartz grains suggest that the three samples deformed to different intensities and temperatures. The EBSD derived CPOs for quartz and magnetite grains are strong, implying dislocation creep as the dominant mechanism. The presence of distinct subgrains in magnetite, rare in natural samples, attests to the same. Furthermore, twinning on {111}, as evident from the misorientation angle and axis distributions, indicates ductile deformation of magnetite below 400 °C. Subgrain boundary trace analysis in selected magnetite grains reveals that multiple-slip planes {111}, {110}, and {100} were operational. Topotaxial replacement, via redox reaction, of magnetite grains along their octahedral planes by hematite is evident. Well-developed CPOs but low (<1°) GOS values of both magnetite and hematite grains suggest that recovery processes in these were rapid. Post-replacement deformation was weak and did not affect the hematite CPOs that were inherited from the relatively more deformed host magnetite grains.

Patterned optical anisotropic film for generation of non-diffracting vortex beams

Bessel vortex beams (BVBs) are endowed with non-diffracting properties and carry specific orbital angular momentum, which adds a new degree of freedom in the manipulation of light. A patterned liquid crystal polymer (LCP)-based optical anisotropic film is proposed and demonstrated for generation of non-diffracting BVBs. The optical axis distribution is induced by the functionalized film, which can simultaneously modulate the amplitude and phase of the wavefront. Different BVB modes can be obtained in this manner. The topological charges and non-diffracting properties of the BVBs are experimentally verified. The multifunctional LCP film exhibits the merits of low power consumption, low cost, and easy fabrication. It may provide a new strategy for beam shaping and planar optics.

Neural-network based approach to optimize THz computer generated holograms

Terahertz (THz) optics often encounters the problem of small f number values (elements have relatively small diameters comparing to focal lengths). The need to redirect the THz beam out of the optical axis or form particular intensity distributions resulted in the application of iterative holographic methods to design THz diffractive elements. Elements working on-axis do not encounter significant improvement while using iterative holographic methods, however, for more complicated distributions the difference becomes meaningful. Here, we propose a totally different approach to design THz holograms, utilizing a neural network based algorithm, suitable also for complicated distributions. Full Text: PDF ReferencesY. Tao, A. Fitzgerald and V. Wallace, "Non-Contact, Non-Destructive Testing in Various Industrial Sectors with Terahertz Technology", Sensors, 20(3), 712 (2020). CrossRef J. O'Hara, S. Ekin, W. Choi and I. Song, "A Perspective on Terahertz Next-Generation Wireless Communications", Technologies, 7(2), 43 (2019). CrossRef L. Yu et al., "The medical application of terahertz technology in non-invasive detection of cells and tissues: opportunities and challenges", RSC Advances, 9(17), 9354 (2019). CrossRef A. Siemion, "The Magic of Optics—An Overview of Recent Advanced Terahertz Diffractive Optical Elements", Sensors, 21(1), 100 (2020). CrossRef A. Siemion, "Terahertz Diffractive Optics—Smart Control over Radiation", J. Infrared Millim. Terahertz Waves, 40(5), 477 (2019). CrossRef M. Surma, I. Ducin, P. Zagrajek and A. Siemion, "Sub-Terahertz Computer Generated Hologram with Two Image Planes", Appl. Sci., 9(4), 659 (2019). CrossRef S. Banerji and B.Sensale-Rodriguez, "A Computational Design Framework for Efficient, Fabrication Error-Tolerant, Planar THz Diffractive Optical Elements", Sci. Rep., 9(1), 5801 (2019). CrossRef J. Sun and F. Hu, "Three-dimensional printing technologies for terahertz applications: A review", Int. J. RF. Microw. C. E., 30(1) (2020). CrossRef E. Castro-Camus, M. Koch and A. I. Hernandez-Serrano, "Additive manufacture of photonic components for the terahertz band", J. Appl. Phys., 127(21), 210901 (2020). CrossRef https://community.wolfram.com/groups/-/m/t/2028026?p_%20479%20p_auth=blBtLb5d DirectLink P. Komorowski, et al., "Three-focal-spot terahertz diffractive optical element-iterative design and neural network approach", Opt. Express, 29(7), 11243-11253 (2021) CrossRef M. Sypek, "Light propagation in the Fresnel region. New numerical approach", Opt. Commun., 116(1-3), 43 (1995). CrossRef

Orientations and matrix function-based centralities in multiplex network analysis of urban public transport

We study urban public transport systems by means of multiplex networks in which stops are represented as nodes and each line is represented by a layer. We determine and visualize public transport network orientations and compare them with street network orientations of the 36 largest German as well as 18 selected major European cities. We find that German urban public transport networks are mainly oriented in a direction close to the cardinal east-west axis, which usually coincides with one of two orthogonal preferential directions of the corresponding street network. While this behavior is present in only a subset of the considered European cities it remains true that none but one considered public transport network has a distinct north-south-like preferential orientation. Furthermore, we study the applicability of the class of matrix function-based centrality measures, which has recently been generalized from single-layer networks to layer-coupled multiplex networks, to our more general urban multiplex framework. Numerical experiments based on highly efficient and scalable methods from numerical linear algebra show promising results, which are in line with previous studies. The centrality measures allow detailed insights into geometrical properties of urban systems such as the spatial distribution of major transport axes, which can not be inferred from orientation plots. We comment on advantages over existing methodology, elaborate on the comparison of different measures and weight models, and present detailed hyper-parameter studies. All results are illustrated by demonstrative graphical representations.

No Sub-Saturn-mass Planet Desert in the CORALIE/HARPS Radial-velocity Sample

Abstract We analyze the CORALIE/HARPS sample of exoplanets found by the Doppler radial-velocity method for signs of the predicted gap or “desert” at 10–100 M ⊕ caused by runaway gas accretion at semimajor axes of &lt;3 au. We find that these data are not consistent with this prediction. This result is similar to the finding by the MOA gravitational microlensing survey that found no desert in the exoplanet distribution for exoplanets in slightly longer period orbits and somewhat lower host masses (Suzuki et al. 2018). Together, these results imply that the runaway gas accretion scenario of the core accretion theory does not have a large influence on the final mass and semimajor axis distribution of exoplanets.