Opposite Angles Research Articles

Role of RKKY torque on domain wall motion in synthetic antiferromagnetic nanowires with opposite spin Hall angles

We experimentally show the effect of enhanced spin-orbit and RKKY induced torques on the current-induced motion of a pair of domain walls (DWs), which are coupled antiferromagnetically in synthetic antiferromagnetic (SAF) nanowires. The torque from the spin Hall effect (SHE) rotates the Néel DWs pair into the transverse direction, which is due to the fact that heavy metals of opposite spin Hall angles are deposited at the top and the bottom ferromagnetic interfaces. The rotation of both DWs in non-collinear fashion largely perturbs the antiferromagnetic coupling, which in turn stimulates an enhanced interlayer RKKY exchange torque that improved the DW velocity. The interplay between the SHE-induced torque and the RKKY exchange torque is validated via micromagnetic simulations. In addition, the DW velocity can be further improved by increasing the RKKY exchange strength.

Effect of rib orientation on thermal and fluid-flow features in a two-pass parallelogram channel with abrupt entrance

Detailed secondary flow patterns, Nusselt number (Nu) distributions, Fanning friction factor (f), and thermal performance factor (TPF) are compared between three different rib orientations (45-deg, −45-deg, and 90-deg) in a stationary two-pass parallelogram channel with an asymmetrically and suddenly contracted inlet condition. Velocity and temperature measurements are performed with Particle Image Velocimetry (PIV) and Infrared Thermometry (IT). Temperature and pressure drop measurements are conducted under Reynolds number (Re) ranging from 5000 to 20,000, while the velocity measurements are carried out at fixed Re=10,000. A cross-sectional equal length, 45.5mm, of adjacent sides is selected and two pairs of opposite angles are 45-deg and 135-deg. The rib-height to channel-height ratio and rib pitch-to-height ratio are 0.1 and 10, respectively. It is found that the combined effect of inlet condition and rib orientation extends to whole parallelogram channel rather than the first passage only. Among the rib orientations investigated, the 45-deg ribs strengthen the effects of parallelogram slant sidewalls and entrance and further widen the Nu difference between top and bottom walls. In contrast, the other two rib configurations, 90-deg ribs especially, weaken these effects and narrow the corresponding differences. Based on the ability to elevate the surface-averaged Nu0‾/Nu∞ ratio, the orders (45-deg, −45-deg, 90-deg) and (90-deg, 45-deg, −45-deg) respectively for present top and bottom walls are significantly distinct from those in square and rectangular channels. The variations of channel-averaged Nu0‾/Nu∞ and f0‾/f∞ with the associated TPF values against Re are plotted and compared with previous results obtained from literature. Overall speaking, three tested angled ribs all provide the TPF values above than unity; however, only the TPF values in 45-deg case are always higher than those in corresponding smooth parallelogram channel (ASI case). Divided by the TPF values in ASI case, the normalized TPF values are respectively 1.09–1.04, 1.07–0.87, and 0.83–0.99 for 45-deg, 90-deg, −45-deg ribbed cases. It is thus important to take the entrance effect into account when applying the angled ribs in a two-pass parallelogram channel.

Objectifying the adjacent and opposite angles: a cultural historical analysis

ABSTRACTThe angle topic is central to the development of geometric knowledge. Two of the basic concepts associated with this topic are the adjacent and opposite angles. It is the goal of the present study to analyze, based on the cultural historical semiotics framework, how high-achieving seventh grade students objectify the adjacent and opposite angles’ concepts. We videoed the learning of a group of three high-achieving students who used technology, specifically GeoGebra, to explore geometric relations related to the adjacent and opposite angles’ concepts. To analyze students’ objectification of these concepts, we used the categories of objectification of knowledge (attention and awareness) and the categories of generalization (factual, contextual and symbolic), developed by Radford. The research results indicate that teacher's and students’ verbal and visual signs, together with the software dynamic tools, mediated the students’ objectification of the adjacent and opposite angles’ concepts. Specifically, eye and gestures perceiving were part of the semiosis cycles in which the participating students were engaged and which related to the mathematical signs that signified the adjacent and the opposite angles. Moreover, the teacher's suggestions/requests/questions included/suggested semiotic signs/tools, including verbal signs that helped the students pay attention, be aware of and objectify the adjacent and opposite angles’ concepts.

An Examination of a Pre-service Mathematics Teacher's Mental Constructions of Relationships in a Right Triangle

Students need to construct strong knowledge of angles as well as relationships between angles and side lengths in a triangle to succeed in geometry. Although many researchers pointed out the importance of angles and angle-related concepts, students and teachers have had limited knowledge of these concepts. This study is a part of a larger study, and examines pre-service secondary mathematics teachers‘ (PSMTs) mental constructions of relationships between angles and side lengths in a right triangle (RASR). The Action-Process-Object-Schema (APOS) learning theory was used as the theoretical lens and clinical interview methodology was used as the methodology in the study. The study was conducted with four PSMTs, but it focuses on one of PSMTs, Linda, who revealed evidence of schema for RASR. As a result of fine-grained analysis of Linda‘s responses to the tasks, this article reports the mental constructions enough to develop a schema for RASR. The model describes that schema for 2-line angles, right triangles and relationships between opposite angles and side lengths and process level for some relationships including ‗Pythagorean Theorem‘, ‗The hypotenuse is always the longest side in a right triangle‘, ‗Special right triangles‘, ‗Complementary Angles‘, and ‗Triangle inequalities‘ are enough to construct a schema for RASR.

High-accuracy biaxial optical extensometer based on 2D digital image correlation

In two-dimensional digital image correlation (2D-DIC), the optical axis of the camera must be exactly perpendicular to the object surface to avoid the generation of out-of-plane displacement, which leads to low strain accuracy. In this work, we first studied the strain accuracy of a common optical extensometer when the optical axis of the camera is not perpendicular to the specimen surface. Derivation reveals that even a very small oblique angle θ will introduce a considerable strain error and that an opposite oblique angle θ generates an opposite strain error of the same magnitude. Therefore, taking the strain average of these two optical extensometers can almost entirely eliminate such effect of non-perpendicularity, which has the same form as the optical extensometer realized by dual-reflector imaging. Because the transverse strain of a specimen is less than its axial strain, the measurement of transverse strain requires higher strain-measurement accuracy. With the aid of a self-designed right-angled apparatus, we conveniently extend this 1D extensometer to a 2D situation, which is called the biaxial optical extensometer. Uniaxial tensile tests of a stainless-steel specimen are conducted to evaluate the strain accuracy of the biaxial optical extensometer quantitatively. Experimental results show that the transverse and axial strains obtained using the proposed biaxial extensometer are in good agreement with those obtained using strain gauges and that the proposed extensometer achieves higher strain accuracy compared to the 3D-DIC extensometer.

Infrared Studies of the Symmetry Changes of the 28SiH4 Molecule in Low-Temperature Matrixes. Fundamental, Combination, and Overtone Transitions.

Infrared spectra of 28SiH4 in argon and nitrogen matrixes at low temperature 6.5-20 K in the region of overtone and combination transitions were recorded for the first time. Additionally, the high-resolution spectra were obtained in the fundamental region. The frequencies and the relative intensities of all bands were determined. The set of experimental data suggests that the symmetry of molecules studied in the matrixes is different from the symmetry of the free molecules because of an interaction with the environment. The symmetry of 28SiH4 changes from Td to C3v on transition from the gas phase to a nitrogen matrix and to D2d on transition to an argon matrix. A modeling of SiH4 molecule force fields explains the experimental data as a change of a force constant of the selected SiH bond in the case of SiH4 in the nitrogen matrix or force constants of two opposite angles in the case of SiH4 in the argon matrix. In spite of small values of these changes, they result in noticeable spectroscopic effects: the band splitting and appearance of new bands in matrix spectra compared with spectra of free SiH4. The interpretation of transitions in the fundamental and combination regions was performed.

A Parametric Model for Contribution of Superthermal Electrons to Oblique Measurement Electron Cyclotron Spectra Under ITER-Like Conditions

For high-temperature tokamaks like ITER, electron cyclotron emission (ECE) measurements are expected to be affected by many factors like relativistic downshift, harmonics overlap, polarization scrambling, deviation of electron distribution from Maxwellian, etc. Many studies are already reported on the difference between ECE measurements and other measurements like Thomson scattering for existing high-temperature tokamaks like JET, TFTR, D-III-D, etc. As ITER is expected to reach a temperature of around 25 keV with a strong electron-ion coupling and additional heating, the deviation of the ECE radiation temperature from the electron temperature needs to be examined. This paper reports a parametric study on the effect of the presence of small superthermal populations on ECE measurements for ITER. A wide range of parametric space for superthermal parameters is used, assuming a bi-Maxwellian electron distribution, which obeys Kirchhoff law. The computational details and the results of the numerical studies are explained in this paper. Further, an attempt is also made to reconstruct the superthermal contributions from multiple oblique measurements, which is otherwise a difficult task. This reconstruction has been done through numerical calculations for two sets of measurements using detectors placed at same but opposite angles. Then, a scale factor is used to scale the difference between these two measurements to superthermal emission. The detailed procedure and possible physical explanations are presented. The dependence of this scale factor on the superthermal parameters is numerically studied, and a parametric equation is drafted between scale factor and superthermal parameters. The said equation contains two numerical constants, for which the values are numerically obtained from one set of simulations and verified with a number of calculations using different superthermal parameters.

The neglected “gift” of Ratzel for/from the Indian Ocean: thoughts on mobilities, materialities and relational spaces

Abstract. When Korf (2014) recently invited (critical) geographers to come to terms with the problematic heritage of our discipline, especially with respect to spatial political thought, he first of all drew our attention to the intellectual contributions of Martin Heidegger and Carl Schmitt. While he urges us to rethink our ongoing references to these key thinkers, especially in light of the rather strict avoidance of politically problematic figures within our own discipline, such as Haushofer and Ratzel, this article now wishes to address geography's (dis)engagement with its politically problematic heritage from the opposite angle: focusing on Friedrich Ratzel, it asks if we might have been too radical in condemning his work as only poison? What if the neglect of Ratzel has actually led to a moment where his ideas feature prominently in current geographical debates without us even noticing it? By drawing on his contributions to cultural geography and, in particular, the establishment of the cultural historical method and German diffusionism, this article takes up on this question and reflects on the (imagined/actual) role of Ratzel's scholarship in contemporary geography. By pointing out striking similarities to more recent discussions about mobility, materiality and relational space, it illustrates the contemporary, though widely unnoticed, (re)appearance of Ratzel's ideas, and uses this example to emphasize the need for more critical reflection concerning the history of our discipline as well as the complex ways in which political ideologies and intellectual reasoning relate to each other.

P101 Impact of coil rotation on TMS threshold

Introduction Conflicting results have been reported on the importance of optimal TMS coil rotation. Maintaining a constant coil rotation angle manually remains a challenge. However, the exact impact of rotation angle on resting motor thresholds (RMTs) has not been investigated to date. Objective Using a robot-guided and a fully automated threshold hunting procedure, we aimed at determining the relevance of optimal rotation for determining RMT. Methods FDI hotspot was located with the automated hotspot hunting procedure ( n = 7). RMTs were then determined applying the threshold-hunting algorithm at different rotation angles (360° in steps of 15°, 15 pulses per rotation angle) in a randomized order over all pulses. The coil handle in posterior position was set as 0°. The procedure was repeated with steps of 5° within a 60° range of lowest thresholds of the first session. Threshold values were normalized for individual min and max. Results With 15° steps mean threshold was lowest at angles of 30° and 45°. Using 5° steps revealed a minimum mean threshold at 40° (mean threshold: 29.0; SEM: 0.05). A second minimum was found at the opposite angle. Highest RMTs were observed at angles between 135° and 180° and 285° and 315°. The relation between the rotation angle and deviation of the measured RMTs (from the minimum RMT at the optimal rotation angle) was non-linear with a floor effect between 5° and 15°. Conclusion Optimal coil rotation angle for FDI was found at 40°. Interestingly, within a range between 25° and 55° the effect of different coil rotation angles on the RMTs was not relevant, i.e. lower than the error of the threshold hunting procedure. The results therefore suggest that manual coil positioning at a rotation angle of 40° with little positional errors is uncritical when assessing motor thresholds of the FDI.

맨드렐을 이용한 엘보우 성형 공정해석

In this study, process analysis of elbow-shaped tubes using a mandrel has been performed. To reach the final shape within the dimensional tolerance, the process analysis has been performed at various processing parameters such as tube dimensions, the curved cutting surface and the radius of curvature. The area outside the boundary of the target shape was expressed as a quantitative index to analyze the formability. The validation experiments have also been performed in order to increase the reliability of the process analysis. For the processing of elbow-shaped tubes, it is preferable to make the angle of the portion where the punch touches the tube smaller than the opposite angle. And the convex cutting surface is advantageous due to the increased contacts between the punch and the tube ends during the bending process. Elbow tube having larger radius of curvature shows higher dimensional accuracy due to the relatively uniform strain distribution.

Imaging of trabecular meshwork using Bessel–Gauss light sheet with fluorescence

Ocular imaging technology that holds promise for both fundamental investigation and clinical detection of glaucoma is still a challenging research area. A direct view of the trabecular meshwork (TM) with high resolution is not generally possible because the iridocorneal angle region is obstructed by the sclera overlap. The best approach to observe the aqueous outflow system (AOS) is therefore to view from the opposite angle. In this research work, we developed two imaging systems for the high resolution ex vivo studies of the AOS inside porcine eye, based on a Gaussian illuminated and a digitally scanned Bessel–Gauss beam light sheet fluorescence configurations. The digitally scanned Bessel–Gauss beam is able to overcome the trade-off between the length and thickness of the Gaussian light sheet to give better imaging performance. It has adequate spatial resolution to resolve critical anatomical structures such as the TM, thereby enabling objective information about the AOS. This non-contact and non-invasive imaging methodology with excellent safety profile is expected to be well received by vision researchers and clinicians in the evaluation and management of glaucoma.

THEORETICAL RESEARCH ON THE VIBRATION MODE OF THE DOUBLE-HELICAL STAR GEAR TRANSMISSION SYSTEM

Vibration and noise are the key concerns in doublehelical star gear transmission system. The vibration and noise can be reduced by planet phasing whose basis is a clearly classification of the vibration mode of doublehelical star gear transmission system.This work uses an analytical model to investigate the natural frequencies and vibration modes. In this model, the double-helical gear are treat as two helical gears with opposite spiral angle connected by massless spring which has the bending, torsion and axial stiffness. Each of the helical gears and carrier have 4 degrees of freedom with coupled lateral-torsional-axial. The natural cyclic frequencies and vibration modes of the system are calculated. Vibration modes are classified into four categories and the multiplicities and values of the eigenvalue are theoretically analyzed. For each class of these modes, reduced-order eigenvalue problems are derived.

Interfaz y heterarquía: diseños de interacción locales para la independencia colaborativa descentralizada

The concept of information technology: interface is used interchangeably to refer to situations related to design projects. Usually associated with referral of company management, especially since the eighties. From an opposite angle, the susceptibility for decentralised collaborative independence was applied experimentally in the Chilean state institutional project; from the twenties to the early seventies. Getting by the end of this period a number of advances in the field of computer science that are now re-valued. In this context the German designer Gui Bonsiepe, from the experience of the HfG-Ulm, coordinated the disappeared Institute of Technology Development Corporation (CORFO INTEC, 1968-1973). In a certain way, he reformulates the proto-informatic concept of interface, synthesising other design interaction initiatives necessary to give a new meaning that can account of a vacuum for a critique of the political economy of the symbolic space in the possible organic exception which would have meant this nationwide conceptualization. It is, therefore, necessary to reconstitute the primary variables and previous models that delimited this "heterarchical" susceptibility. As situation and specific susceptibility of enunciation of a fundamental concept between information and communication technology.

Interfaz y heterarquía: diseños de interacción locales para la independencia colaborativa descentralizada

El concepto de tecnologías de la información interface, se usa indistintamente para referirse a situaciones proyectuales vinculadas al diseño. Habitualmente asociado como derivación del manejo de empresas, especialmente desde los años 80. Desde un ángulo opuesto, la susceptibilidad para la independencia colaborativa descentralizada fue aplicada de manera experimental en el proyecto institucional estatal chileno; desde los años 20 a los primeros años 70, consiguiendo a fines de este período diversos avances en el ámbito de la informática que hoy son revalorizados. En este contexto el diseñador alemán Gui Bonsiepe, proveniente de la experiencia de la HfG-Ulm, coordinó el desaparecido Instituto Tecnológico de la Corporación de Fomento (INTEC CORFO, 1968-1973). Es aquí donde de cierta manera reformula el proto infomático concepto de interfaz, sintetizando otras iniciativas de diseño de interacción necesarias de resignificar que pueden dar cuenta de un vacío para una crítica a la economía política del espacio de lo simbólico en la posible excepcionalidad orgánica que habría significado esta conceptualización a escala nacional. Se hace, por tanto, necesario reconstituir las principales variables y modelos precedentes que delimitaron esta susceptibilidad “heterárquica”. Como situación y susceptibilidad específica de enunciación de un concepto fundamental entre tecnologías de la información y comunicación.

Vertical spin Hall magnetoresistance inTa1−xPtx/YIGbilayers

The spin Hall effect and the magnetic proximity effect are two main sources of the magnetoresistance (MR) effects in heavy metal/ferromagnet bilayers, where they play isolated roles but are usually contaminated by each other. In $\mathrm{T}{{\mathrm{a}}_{1}}_{\ensuremath{-}x}\mathrm{P}{\mathrm{t}}_{x}/\mathrm{YIG}\phantom{\rule{0.16em}{0ex}}(={\mathrm{Y}}_{3}\mathrm{F}{\mathrm{e}}_{5}{\mathrm{O}}_{12})$ bilayers consisting of Ta and Pt nanograins, these effects are intrinsically coupled to generate new MR with 360\ifmmode^\circ\else\textdegree\fi{} direction sensitivity to the magnetic field and proportionality to the out-of-plane magnetization of YIG. Due to the opposite spin Hall angle of Ta and Pt, vertical spin accumulation is generated via the spin Hall effect at the transverse boundaries between Ta and Pt grains. The spin-dependent scattering by the proximity-induced Pt magnetization finally leads to the MR, which is named as vertical spin Hall MR taking the role of spin Hall angle into account. Besides fundamental insight to spin transport physics, our work provides an approach to detecting perpendicular magnetization in a variety of magnets.

Numerical Investigation of Wake Control Strategies for Maximizing the Power Generation of Wind Farm

In order to maximize the total power generation of a wind farm, several control strategies based on tilt angle, yaw angle, and cone angle were investigated numerically using computational fluid dynamics (CFD) simulation. The full rotor model (FRM) of 5 MW wind turbine was used to simulate the wake in the wind farm. According to the comparison of different cases' power generations and velocity fields, the result indicates that appropriate strategies based on tilt angle and positive yaw angle have effective improvements on the power output of whole wind farm, but changing cone angle and opposite yaw angle result in negative effects.

Commentary: Patient Cost Sharing and Medical Expenditures for the Elderly.

Commentary: Patient Cost Sharing and Medical Expenditures for the Elderly.

Co-rotating vortex interaction

Purpose The purpose of this paper is to study the structure and dynamic development of a pair of co-rotating trailing vortices, during their formation, interaction and merging, using detailed experimental measurements of the velocity and vorticity fields. Design/methodology/approach The vortices were generated using two half wings (NACA0030) positioned at equal and opposite angles of attack at the entrance of the test section of an open-circuit, subsonic, wind tunnel. Velocity vector measurements were obtained at Rec = 133,000, on cross-plane grids at several distances from the trailing edges of the wings, using an in-house developed four-sensor hot wire anemometer probe. Findings The results include cross-plane contour plots of the mean and fluctuating velocity as well as mean vorticity fields. Each of these variables is affected in a different way, providing complementary information on the development of the flow field. After shedding, the two vortices are swept along the stream-wise direction and spiral around each other, thereby developing a braid of two vortices, which then deforms the external flow field. Gradually, the interaction with the external flow field links both vortices together until the final merging and the formation of a new stable linear vortex emerges. Practical implications Trailing vortices have been rendered particularly important during the past decades, because of increasing traffic density of very heavy aircrafts and several plane “incidents”, which were attributed to the action of the vortex wake. Originality/value The presented results provide information on the evolution and merging of a pair of vortices formed by a closely spaced differential wing configuration. The vortices interact almost immediately after shedding as expected in flap–flap or flap–wing vortices interaction.

New Binary Hausdorff Symmetry measure based seeded region growing for retinal vessel segmentation

Automated retinal vessel segmentation plays an important role in computer-aided diagnosis of serious diseases such as glaucoma and diabetic retinopathy. This paper contributes, (1) new Binary Hausdorff Symmetry (BHS) measure based automatic seed selection, and (2) new edge distance seeded region growing (EDSRG) algorithm for retinal vessel segmentation. The proposed BHS measure directly provides a binary symmetry decision at each pixel without the computation of continuous symmetry map and image thresholding. In a multiscale mask, the BHS measure is computed using the distance sets of opposite direction angle bins with sub-pixel resolution. The computation of the BHS measure from the Hausdorff distance sets involves point set matching based geometrical interpretation of symmetry. Then, we design a new edge distance seeded region growing (EDSRG) algorithm with the acquired seeds. The performance evaluation in terms of sensitivity, specificity and accuracy is done on the publicly available DRIVE, STARE and HRF databases. The proposed method is found to achieve state-of-the-art vessel segmentation accuracy in three retinal databases; DRIVE-sensitivity (0.7337), specificity (0.9752), accuracy (0.9539); STARE-sensitivity (0.8403), specificity (0.9547), accuracy (0.9424); and HRF-sensitivity (0.8159), specificity (0.9525), accuracy (0.9420).

Vibratory strain field measurement by transverse digital holography.

A method is presented for measuring vibratory strain fields using phase-stepped, image-plane digital holography. An object surface is observed along its normal vector while illuminated at equal and opposite angles by two mutually coherent laser beams. One beam is phase stepped by quarter-wavelength increments between TV frames, and the resulting images are processed to yield holographic images. Object vibrations result in zero-order Bessel function fringes in the display. The second beam is modulated at the same frequency of the object vibration and is used to shift the fringes in a manner analogous to phase step interferometry. The resulting images are processed to yield a wrapped phase map, which is unwrapped and corrected for the error associated with using zero-order Bessel functions in place of cosine functions. The unwrapped images are processed to obtain the average slopes for image segments, and these slopes are multiplied by a scale factor to convert them to strain. The analysis program used here divides the field of view into five horizontal by four vertical segments, which provide a map of the vibratory strain field.