Journal articles: 'Angular orientation'

1

André, Jorge C. S., João C. Gonçalves, Gilberto C. Vaz, and Domingos X. Viegas. "Angular variation of fire rate of spread." International Journal of Wildland Fire 22, no. 7 (2013): 970. http://dx.doi.org/10.1071/wf12028.

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Laboratory fire tests were performed in still air, for variable inclinations (10°, 15°) and fuel bed dimensions (1.28×2.50–3.0×4.6m2), with homogeneous fuel beds of pine needles and pine wood excelsior. The fire ignition was made at a point, along a closed line with no fuel inside and along a straight edge of the fuel bed. The tests were recorded with an infrared camera and various techniques were developed to implement direct and indirect empirical methods of construction of the ‘orientation function’ of the fire in the given fuel bed and ambient conditions, showing how the rate of spread of a steady straight fire front depends on its orientation on the terrain. The direct method uses a set of straight fire fronts with various orientations whereas the indirect method uses essentially a point ignited fire front. Contrary to what is assumed in BehavePlus model, the orientation function is observed to depend significantly on the properties of the fuel bed. In all tests with closed fire fronts, the full steadiness required by the indirect method was not achieved (namely, at the head of the front), although, for slope angle of 10°, the corresponding errors induced on the orientation function were small.

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Furukawa, Minoru, Yukihide Fukuda, Keiichiro Oh-ishi, Z. Horita, and Terence G. Langdon. "An Investigation of Deformation in Copper Single Crystals Using Equal-Channel Angular Pressing." Materials Science Forum 503-504 (January 2006): 113–18. http://dx.doi.org/10.4028/www.scientific.net/msf.503-504.113.

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This paper describes experiments in which high purity copper single crystals of two different orientations were processed for one pass by equal-channel angular pressing (ECAP) and the deformed structures were examined using optical microscopy (OM), orientation imaging microscopy (OIM) and transmission electron microscopy (TEM). The first single crystal (0° specimen) was oriented within the entrance channel of the die so that the {111} slip plane and the <110> slip direction were parallel to the theoretical shear plane and shear direction, respectively. The second crystal (20° specimen) was oriented with the {111} slip plane and the <110> slip direction rotated by 20° in a clockwise sense from the theoretical shear plane and shear direction, respectively. For the 0° specimen, after passing through the shear plane there were two crystallographic orientations representing the initial orientation and an orientation rotated by 60° in a counter-clockwise sense from the initial orientation. For the 20° specimen, there was an orientation rotated by 20° in a counter-clockwise sense from the initial orientation after passing through the shear plane.

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Stanischewski, Sarah, Carolin S. Altmann, Anselm Brachmann, and Christoph Redies. "Aesthetic Perception of Line Patterns: Effect of Edge-Orientation Entropy and Curvilinear Shape." i-Perception 11, no. 5 (September 2020): 204166952095074. http://dx.doi.org/10.1177/2041669520950749.

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Curvilinearity is a perceptual feature that robustly predicts preference ratings for a variety of visual stimuli. The predictive effect of curved/angular shape overlaps, to a large degree, with regularities in second-order edge-orientation entropy, which captures how independent edge orientations are distributed across an image. For some complex line patterns, edge-orientation entropy is actually a better predictor for what human observers like than curved/angular shape. The present work was designed to disentangle the role of the two features in artificial patterns that consisted of either curved or angular line elements. We systematically varied these patterns across two more dimensions, edge-orientation entropy and the number of lines. Eighty-three participants rated the stimuli along three aesthetic dimensions ( pleasing, harmonious, and complex). Results showed that curved/angular shape was a stronger predictor for ratings of pleasing and harmonious if the stimuli consisted of a few lines that were clearly discernible. By contrast, edge-orientation entropy was a stronger predictor for the ratings if the stimuli showed many lines, which merged into a texture. No such differences were obtained for complexity ratings. Our findings are in line with results from neurophysiological studies that the processing of shape and texture, respectively, is mediated by different cortical mechanisms.

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Weichan Yu, K. Daniilidis, and G. Sommer. "Approximate orientation steerability based on angular Gaussians." IEEE Transactions on Image Processing 10, no. 2 (2001): 193–205. http://dx.doi.org/10.1109/83.902274.

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Milner, Valery, and Yehiam Prior. "Biaxial spatial orientation of atomic angular momentum." Physical Review A 59, no. 3 (March 1, 1999): R1738—R1741. http://dx.doi.org/10.1103/physreva.59.r1738.

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Quinn, T., and J. Binney. "Galactic accretion and angular momentum re-orientation." Monthly Notices of the Royal Astronomical Society 255, no. 4 (April 15, 1992): 729–36. http://dx.doi.org/10.1093/mnras/255.4.729.

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Kang, Pilgyu, Xavier Serey, Yih-Fan Chen, and David Erickson. "Angular Orientation of Nanorods Using Nanophotonic Tweezers." Nano Letters 12, no. 12 (November 14, 2012): 6400–6407. http://dx.doi.org/10.1021/nl303747n.

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Kang, Pilgyu, Xavier Serey, Yih-Fan Chen, Dakota O'Dell, and David Erickson. "Near-Field Angular Orientation of Biological Materials." Biophysical Journal 104, no. 2 (January 2013): 676a. http://dx.doi.org/10.1016/j.bpj.2012.11.3733.

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Chen, Chao-Yi, P. J. Kim, and D. T. Walker. "Angular Bias Errors in Three-Component Laser Velocimeter Measurements." Journal of Fluids Engineering 118, no. 3 (September 1, 1996): 555–61. http://dx.doi.org/10.1115/1.2817794.

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For three-component laser velocimeter systems, the change in projected area of the coincident measurement volume for different flow directions will introduce an “angular” bias in naturally sampled data. In this study, the effect of turbulence level and orientation of the measurement volumes on angular bias errors was examined. The operation of a typical three-component laser velocimeter was simulated using a Monte Carlo technique. Results for the specific configuration examined show that for turbulence levels less than 10 percent no significant bias errors in the mean velocities will occur and errors in the root-mean-square (r.m.s.) velocities will be less than 3 percent for all orientations. For turbulence levels less than 30 percent, component mean velocity bias errors less than 5 percent of the mean velocity vector magnitude can be attained with proper orientation of the measurement volume; however, the r.m.s. velocities may be in error as much as 10 percent. For turbulence levels above 50 percent, there is no orientation which will yield accurate estimates of all three mean velocities; component mean velocity errors as large as 15 percent of the mean velocity vector magnitude may be encountered.

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Okai, Daisuke, Atsushi Yamamoto, Toshiya Doi, and Hiroki Adachi. "Characteristics of Cube Orientation for Pure Iron Tape Fabricated by Cold Rolling and Annealing." Materials Science Forum 1016 (January 2021): 1830–34. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.1830.

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A pure iron tape with cube orientation was fabricated by cold rolling and annealing. The orientation characteristics of the pure iron tape were evaluated using electron back-scattering diffraction (EBSD) analysis. The secondary recrystallized grains with cube orientation was formed on the tape surface for the pure iron tape. The coarse grains with a grain size of ca. 1mm were observed on the tape surface. The areal fraction of cube orientations with an angular deviation ≤ 20 ̊ amounts to ca. 81%.

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Leonov, A. I., and P. N. Nikolaev. "Providing Nanosatellite Triaxial Gravitational Orientation Using Magnetic Actuators." IOP Conference Series: Materials Science and Engineering 1215, no. 1 (January 1, 2022): 012005. http://dx.doi.org/10.1088/1757-899x/1215/1/012005.

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Abstract Three-axis gravity stabilization of 3U CubeSat is achieved due to selection of the nanosatellite moments of inertia at the design stage, as well as special modes included in the algorithm to provide stabilization of CubeSat relative to each motion channel separately. In this paper, we propose a modified algorithm based on the magnetic stabilization algorithm B-dot. The modified algorithm provides three modes intended to damp the initial angular velocity to the value of the orbital angular velocity, to keep the angular velocity at a value close to that of the orbital angular velocity, and to provide the nanosatellite gravitational triaxial stabilization by using one magnetic coil located on the axis with the transversal moment of inertia, which is possible due to the small angle between the magnetic field line and the satellite's trajectory. We propose two modifications for forming a control loop for orientation and stabilization of the 3U CubeSat: the first one uses measurements from magnetometers and angular rate sensors as feedback, and the second one, only magnetometers. The efficiency of the two modifications of modifications was studied by means of statistical modeling.

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He, Jianhan, and Ulrich Bismayer. "Polarized mapping Raman spectroscopy: identification of particle orientation in biominerals." Zeitschrift für Kristallographie - Crystalline Materials 234, no. 6 (May 27, 2019): 395–400. http://dx.doi.org/10.1515/zkri-2019-0004.

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Abstract The identification of the texture of biominerals and the particle orientation in the bivalve shells of Anodonta cygnea was performed using polarized Raman spectroscopy mapping measurements. A single crystal of aragonite served as a reference to disclose orientational information on the mesoscopic scale. The relative intensities of different Raman modes combined with the determination of depolarization ratio of the Ag Raman mode at 1087 cm−1 of an aragonite single crystal was used to indicate the angular variation of aragonite crystallites in biominerals. The imaging technique shows that the a- and b-axis of aragonite crystallites in both, nacreous and prismatic layers do not only have one orientation but they are organized in a domain-type arrangement. The angular divergence in the prismatic layer of the shells is larger and hence, the crystallites in the nacreous layer have a higher degree of co-orientation. Results provide relevant textural information about aragonitic shells and indicate a sensitive technique to evaluate the crystal orientation in biominerals.

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Westerdale, John C., Ronald Adrian, Kyle Squires, Hari Chaliki, and Marek Belohlavek. "Effects of Bileaflet Mechanical Mitral Valve Rotational Orientation on Left Ventricular Flow Conditions." Open Cardiovascular Medicine Journal 9, no. 1 (June 26, 2015): 62–68. http://dx.doi.org/10.2174/1874192401509010062.

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We studied left ventricular flow patterns for a range of rotational orientations of a bileaflet mechanical heart valve (MHV) implanted in the mitral position of an elastic model of a beating left ventricle (LV). The valve was rotated through 3 angular positions (0, 45, and 90 degrees) about the LV long axis. Ultrasound scans of the elastic LV were obtained in four apical 2-dimensional (2D) imaging projections, each with 45 degrees of separation. Particle imaging velocimetry was performed during the diastolic period to quantify the in-plane velocity field obtained by computer tracking of diluted microbubbles in the acquired ultrasound projections. The resulting velocity field, vorticity, and shear stresses were statistically significantly altered by angular positioning of the mechanical valve, although the results did not show any specific trend with the valve angular position and were highly dependent on the orientation of the imaging plane with respect to the valve. We conclude that bileaflet MHV orientation influences hemodynamics of LV filling. However, determination of ‘optimal’ valve orientation cannot be made without measurement techniques that account for the highly 3-dimensional (3D) intraventricular flow.

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Liu, Xu-dong, Dong-guang Li, and Qiang Shen. "Swerving Orientation of Spin-Stabilized Projectile for Fixed-Cant Canard Control Input." Mathematical Problems in Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/173571.

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Due to the large launch overload and high spin rate of spin-stabilized projectile, no attitude sensor is adopted in square crossing fixed-cant canard concept, which causes the lack of existing projectile linear theory for the close form solution of swerving motion. This work focuses on swerving orientation prediction with the restricted conditions. By importing the mathematical models of canard force and moment into the projectile angular motion equations, trim angle induced by canard control force is extracted as the analytical solution of angle of attack increment (AOAI). On this basis, analytical orientations of trajectory angular rate increment and swerving increment are obtained via the frozen coefficient method. A series of simulations under different conditions were implemented to validate the expressions in this effort. Results state that increment orientation of swerving motion can be predicted with available trajectory parameters. The analytical orientations indicate trim value of numerical orientations. Deviations between analytical and numerical orientations relate to initial launch angles and control start time, both lower initial launch angle, and the start time which is closer to the end of flight decreases the deviation convergence time.

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Murooka, Y., N. Tanaka, and M. Hibino. "Angular - Resolved Electron - Energy - Loss - Spectroscopy of Perovskite Manganeese Oxide." Microscopy and Microanalysis 6, S2 (August 2000): 202–3. http://dx.doi.org/10.1017/s143192760003350x.

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Among perovskite manganese oxide systems, La1-xSrxMnO3, has been intensely investigated because of its interesting magnetic and electronic properties such as colossal magneto resistance (CMR). These properties are largely determined by the electronic structure of the valence electrons. The electronic structure of the electrons in the energy states near the Fermi level was probed by using electronic excitations of less than a few eV. Ordinarily, the information obtained about the energy states was integrated over all crystal orientations, and only few anisotropic systems were studied in terms of their orientation dependence. In the present study, we reported an orientation dependence of the plasmon dispersion, which corresponded to electronic excitations of 30eV and characterized the collective excitation of the valance electrons, on an isotropic system La,.xSrxMn03 (x=0.4) by angular-resolved electron energy loss spectroscopy (EELS).

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Miyamoto, Hiroyuki, J. Fushimi, Takura Mimaki, Alexei Vinogradov, and Satoshi Hashimoto. "The Effect of the Initial Orientation on Microstructure Development of Copper Single Crystals Subjected to Equal-Channel Angular Pressing." Materials Science Forum 503-504 (January 2006): 799–804. http://dx.doi.org/10.4028/www.scientific.net/msf.503-504.799.

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Copper single crystals were subjected to equal-channel angular pressing (ECAP) via the so-called route A and Bc, in order to examine the influence of initial crystallographic orientation and processing route on microstructure development and grain fragmentation. Microstructural changes were examined by transmission electron microscopy (TEM). The pressing via the route Bc resulted in finer microstructure for all orientations in terms of grain size, equiaxiality and orientation scattering after four passes. Effect of initial crystallographic orientation on the grain refinement was also recognized, and it might be attributed to heterogeneous deformation such as shear bands, whose formation is strongly orientation dependent. After eight passes, however, the effect of processing route and initial orientation cannot be recognized.

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Fuhs, Mark C., Shea R. VanRhoads, Amanda E. Casale, Bruce McNaughton, and David S. Touretzky. "Influence of Path Integration Versus Environmental Orientation on Place Cell Remapping Between Visually Identical Environments." Journal of Neurophysiology 94, no. 4 (October 2005): 2603–16. http://dx.doi.org/10.1152/jn.00132.2005.

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To assess the effects of interactions between angular path integration and visual landmarks on the firing of hippocampal neurons, we recorded from CA1 pyramidal cells as rats foraged in two identical boxes with polarizing internal cues. In the same-orientation condition, following an earlier experiment by Skaggs and McNaughton, the boxes were oriented identically and connected by a corridor. In the opposite-orientation condition, the boxes were abutted by rotating them 90° in opposite directions, so that their orientations differed by 180°. After 16–23 days of pretraining on the same-orientation condition, three rats experienced both conditions in counterbalanced order on each of two consecutive days. On the third day they ran two opposite-orientation trials. Although Skaggs and McNaughton observed stable partial “remapping” of place fields, none of the fields in this experiment remapped in the same-orientation condition. In the opposite-orientation condition, place fields in the first box were isomorphic with those in the same-orientation condition, whereas in the second box the rats eventually exhibited completely different fields. The rats differed as to the trial in which this first occurred. Once the second box exhibited different fields, it continued to do so in all subsequent opposite-orientation trials, yet fields remained the same in subsequent same-orientation trials. The results demonstrate that when animals move actively between environments, and are thus potentially able to maintain their inertial angular orientation, discordance between environmental orientation and the rat's idiothetic direction sense can profoundly affect the hippocampal map—either immediately, or as a result of cumulative experience.

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Megalingam, Rajesh Kannan, Deepak Nagalla, Ravi Kiran Pasumarthi, Vamsi Gontu, and Phanindra Kumar Allada. "Angular Orientation of Steering Wheel for Differential Drive." Advances in Science, Technology and Engineering Systems Journal 5, no. 3 (2020): 275–83. http://dx.doi.org/10.25046/aj050336.

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Bartschat, K. "Angular momentum orientation in elastic electron-atom scattering." Journal of Physics B: Atomic and Molecular Physics 20, no. 23 (December 14, 1987): L815—L819. http://dx.doi.org/10.1088/0022-3700/20/23/008.

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Rauch, E. F., and M. Véron. "Crystal Orientation Angular Resolution with Precession Electron Diffraction." Microscopy and Microanalysis 22, S3 (July 2016): 500–501. http://dx.doi.org/10.1017/s1431927616003354.

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Walker, P. M. "Angular momentum orientation at bandcrossings in rotating nuclei." Journal of Physics G: Nuclear and Particle Physics 34, no. 1 (November 8, 2006): 123–27. http://dx.doi.org/10.1088/0954-3899/34/1/008.

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Beloshenko, V. A., V. N. Varyukhin, A. V. Voznyak, and Yu V. Voznyak. "Polyoxymethylene orientation by equal-channel multiple angular extrusion." Journal of Applied Polymer Science 126, no. 3 (April 13, 2012): 837–44. http://dx.doi.org/10.1002/app.36971.

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Cohen, Bernard, Susan Wearne, Mingjia Dai, and Theodore Raphan. "Spatial orientation of the angular vestibulo-ocular reflex." Journal of Vestibular Research 9, no. 3 (June 1, 1999): 163–72. http://dx.doi.org/10.3233/ves-1999-9303.

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During vestibular nystagmus, optokinetic nystagmus (OKN), and optokinetic afternystagmus (OKAN), the axis of eye rotation tends to align with the vector sum of linear accelerations acting on the head. This includes gravitational acceleration and the linear accelerations generated by translation and centrifugation. We define the summed vector of gravitational and linear accelerations as gravito-inertial acceleration (GIA) and designate the phenomenon of alignment as spatial orientation of the angular vestibuloocular reflex (aVOR). On the basis of studies in the monkey, we postulated that the spatial orientation of the aVOR is dependent on the slow (velocity storage) component of the aVOR, not on the short latency, compensatory aVOR component, which is in head-fixed coordinates. Experiments in which velocity storage was abolished by midline medullary section support this postulate. The velocity storage component of the aVOR is likely to be generated in the vestibular nuclei, and its spatial orientation was shown to be controlled through the nodulus and uvula of the vestibulo-cerebellum. Separate regions of the nodulus/uvula appear to affect the horizontal and vertical/torsional components of the response differently. Velocity storage is weaker in humans than in monkeys, but responds in a similar fashion in both species. We postulate that spatial orientation of the aVOR plays an important role in aligning gaze with the GIA and in maintaining balance during angular locomotion.

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Sanko, A. A., and A. A. Sheinikov. "Angular orientation determination in SINS: traditional algorithms comparison." Civil Aviation High Technologies 25, no. 1 (February 28, 2022): 77–88. http://dx.doi.org/10.26467/2079-0619-2022-25-1-77-88.

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The principle of organization of strap-down inertial navigation systems is based on numerical integration of angular velocities and accelerations. The purpose of numerical integration algorithms is to approximate the behavior of a dynamic system (unmanned aerial vehicle – UAV) with continuous time using a digital computer. The efficiency of numerical integration is determined by the accuracy and stability of the computational process. The integration algorithm may have a small integration error, but at the same time be inefficient due to the instability of the numerical method when the step or conditions of integration change. The standard way to test integration algorithms for stability is to test them under control operating conditions (when performing a typical UAV flight along the route and canonical movement). The article presents the results of simulation modeling of traditional numerical integration algorithms in the conditions of rectilinear and conical UAV motion, when calculating the values of angular velocities by various methods. The analysis of the obtained research results is carried out, which allows us to choose an algorithm that has an advantage with respect to accuracy and computational simplicity, depending on the flight conditions. For a UAV that has no or minimal undampened angular harmonic oscillations of its body, when performing a typical flight along the route, the best, in terms of accuracy and volume of calculations, is a second-order accuracy algorithm implementing the average speed method. Its average error in calculating angles ranges from 3.6 to 43%, which is approximately equal to the errors values when using the considered algorithms (an algorithm implementing a second approximation to the average speed method, a one-step algorithm of the thirdorder of accuracy), with a three-fold smaller amount of mathematical calculations.

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Furukawa, Minoru, Z. Horita, and Terence G. Langdon. "Application of Equal-Channel Angular Pressing to Aluminum and Copper Single Crystals." Materials Science Forum 539-543 (March 2007): 2853–58. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.2853.

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This paper describes experiments in which high purity aluminum (Al) and copper (Cu) single crystals of different crystallographic orientations were processed for one pass by equal-channel angular pressing (ECAP). The deformed structures were examined using optical microscopy (OM), orientation imaging microscopy (OIM) and transmission electron microscopy (TEM). The results for Al single crystals are compared with those for Cu single crystals.

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Sidorov, Ilya Andreevich, and Alexander Alekseevich Manoilenko. "MATHEMATICAL MODEL FOR SOLVING THE NAVIGATION PROBLEM AND ANGULAR ORIENTATION SPACECRAFT." Journal of Rocket-Space Technology 27, no. 4 (December 30, 2019): 101–8. http://dx.doi.org/10.15421/451915.

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Currently, there is an increased interest in the creation of strapdown inertial navigation systems (SINS), which make up the information core of modern airborne systems for the orientation and navigation of spacecraft (SC). An urgent problem arises, which is associated with the development of high-precision algorithms for estimating and filtering data from the sensors of the SC motion parameters, the mathematical model of the SINS, calculating its errors and analyzing the effect of errors on the characteristics of the navigation system and orientation of the SC. A mathematical model is proposed for solving the problem of navigation and angular orientation of a small SC equipped with electromagnetic control elements, taking into account the filtering of “noisy” magnetometer data. The requirements are set for the accuracy of the angular orientation and stabilization of the SC in the mode of maintaining the triaxial orientation of the SC in the orbital coordinate system (OCS) and for the duration of the damping mode of the angular velocities obtained by the SC during separation from the launch vehicle (LV), and the mode of the initial construction of the triaxial orientation of the SC in OCS. The mathematical model includes: a model of the motion of the center of mass of the SC in the osculating elements of the orbit with specified parameters, a model of the angular motion of the SC around the center of mass, a model of the Earth’s magnetic field (EMF) and a model of filtering magnetometer data. As an arithm for filtering data from a magnetometer on the components of the magnetic induction vector of the EMF, a one-parameter algorithm of exponential smoothing (exponential moving average) is used, which belongs to the class of first-order filters with an infinite impulse response. The results of numerical simulation of the dynamic processes of navigation and the angular orientation of the SC after separation from the LV taking into account the filtering of magnetometer data by the method of exponential smoothing using mathematical models are presented, and the accuracy of the angular orientation and stabilization of the SC is estimated.

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Giovanni Milione, Giovanni Milione, Ting Wang Ting Wang, Jing Han Jing Han, and and Lianfa Bai and Lianfa Bai. "Remotely sensing an object’s rotational orientation using the orbital angular momentum of light (Invited Paper)." Chinese Optics Letters 15, no. 3 (2017): 030012–30016. http://dx.doi.org/10.3788/col201715.030012.

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Furukawa, Minoru, Z. Horita, and Terence G. Langdon. "Microstructures of Aluminum and Copper Single Crystals Processed by Equal-Channel Angular Pressing." Materials Science Forum 638-642 (January 2010): 1946–51. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1946.

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High purity aluminum (Al) and copper (Cu) single crystals of different crystallographic orientations were processed for one pass by equal-channel angular pressing (ECAP). The deformed structures were examined using orientation imaging microscopy (OIM) and transmission electron microscopy (TEM). This paper examines the experimental results in terms of the values of the shear factors based on simple shear theory.

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Stančin, Sara, and Sašo Tomažič. "On the Interpretation of 3D Gyroscope Measurements." Journal of Sensors 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/9684326.

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We demonstrate that the common interpretation of angular velocities measured by a 3D gyroscope as being sequential Euler rotations introduces a systematic error in the sensor orientation calculated during motion tracking. For small rotation angles, this systematic error is relatively small and can be mistakenly attributed to different sources of sensor inaccuracies, including output bias drift, inaccurate sensitivities, and alignments of the sensor sensitivity axes as well as measurement noise. However, even for such small angles, due to accumulation over time, the erroneous rotation interpretation can have a significant negative impact on the accuracy of the computed angular orientation. We confirm our findings using real-case measurements in which the described systematic error just worsens the deleterious effects typically attributed to an inaccurate sensor and random measurement noise. We demonstrate that, in general, significant improvement in the angular orientation accuracy can be achieved if the measured angular velocities are correctly interpreted as simultaneous and not as sequential rotations.

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Yang, Zhicheng, Bert-Jan F. van Beijnum, Bin Li, Shenggang Yan, and Peter H. Veltink. "Estimation of Relative Hand-Finger Orientation Using a Small IMU Configuration." Sensors 20, no. 14 (July 19, 2020): 4008. http://dx.doi.org/10.3390/s20144008.

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Relative orientation estimation between the hand and its fingers is important in many applications, such as virtual reality (VR), augmented reality (AR) and rehabilitation. It is still quite a big challenge to do the estimation by only exploiting inertial measurement units (IMUs) because of the integration drift that occurs in most approaches. When the hand is functionally used, there are many instances in which hand and finger tips move together, experiencing almost the same angular velocities, and in some of these cases, almost the same accelerations are measured in different 3D coordinate systems. Therefore, we hypothesize that relative orientations between the hand and the finger tips can be adequately estimated using 3D IMUs during such designated events (DEs) and in between these events. We fused this extra information from the DEs and IMU data with an extended Kalman filter (EKF). Our results show that errors in relative orientation can be smaller than five degrees if DEs are constantly present and the linear and angular movements of the whole hand are adequately rich. When the DEs are partially available in a functional water-drinking task, the orientation error is smaller than 10 degrees.

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Yadav, Shiv Narayan, and Santosh Kumar Sah. "Study of Spatial Orientation of Angular Momentum of z-Magnitude SDSS DR-13 Galaxies with Red Shift 0.50 to 0.53." Journal of Institute of Science and Technology 26, no. 1 (June 16, 2021): 1–7. http://dx.doi.org/10.3126/jist.v26i1.37805.

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The spatial orientations of 142,929 SDSS DR-13, z- magnitude galaxies having red shift 0.50 to 0.53 have been analyzed. The main goal of this work is to examine the orientation of the angular momentum of galaxies within the given redshift limit in the framework of three different scenarios 'Hierarchy model', 'Pancake model', and the 'Primordial vorticity model'. By using Godlowskian transformation the two-dimensional data were converted into three-dimensional data (polar and azimuthal angles). The expected isotropy distribution curves were obtained by removing the selection effects and performing a random simulation to generate 107 virtual galaxies by using Matlab 2015a. Three statistical tests of Chi-square, autocorrelation, and Fourier were used to compare the expected isotropic data with observed. The data classified into nine subsamples having each of one magnitude size. In general, the results supported the Hierarchy model. The model advocates random orientations of angular. However, a local anisotropy observed in few subsamples suggested a gravitational tidal interaction between neighboring galaxies, an early-merging process in which the angular momentum vector distorts the initial alignment of nearby galaxies.

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Harris, A. L., and T. P. Esposito. "Angular momentum and orientation effects in excitation-ionization collisions." Journal of Physics B: Atomic, Molecular and Optical Physics 49, no. 16 (August 5, 2016): 165202. http://dx.doi.org/10.1088/0953-4075/49/16/165202.

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Onuora, L. I. "Radio source orientation and the angular diameter-redshift relation." Astrophysical Journal 377 (August 1991): 36. http://dx.doi.org/10.1086/170334.

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Libeskind, Noam I., Yehuda Hoffman, Alexander Knebe, Matthias Steinmetz, Stefan Gottlöber, Ofer Metuki, and Gustavo Yepes. "The cosmic web and the orientation of angular momenta." Monthly Notices of the Royal Astronomical Society: Letters 421, no. 1 (February 27, 2012): L137—L141. http://dx.doi.org/10.1111/j.1745-3933.2012.01222.x.

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Ishtiaque, S. M., and Alok Kumar. "Impact of progressive yarn extension on angular fibre orientation." Journal of The Textile Institute 111, no. 11 (February 21, 2020): 1662–73. http://dx.doi.org/10.1080/00405000.2020.1729648.

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Seelig, Johannes D., and Vivek Jayaraman. "Neural dynamics for landmark orientation and angular path integration." Nature 521, no. 7551 (May 2015): 186–91. http://dx.doi.org/10.1038/nature14446.

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Yin, Ji Bin, and Tao Liu. "Investigation to Angular Resolution in Cube-Orientation-Based Interactions." Advanced Materials Research 569 (September 2012): 785–88. http://dx.doi.org/10.4028/www.scientific.net/amr.569.785.

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This study empirically explores a cube-shaped tool, focusing on the properties of its angle input. By tracking the fiducial marker on each side of the cube in real-time, basic operations such as rotating and tilting can produce the angle input modalities. We conduct an experiment that investigates the use of the angle input to perform a set of experimental tasks. In the experiment we design an angle selection task, varying the angle position and interval. The experimental results show that for rotation angle even 1 degree of angle can still be accurately discriminated whereas that limit goes beyond 3 degrees in case of tilt. A logarithm model can describe the relationship between angle interval and selection time.

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Serrano-Ensástiga, E. "A rotating quantum system without angular momentum and shape deformations." Revista de la Escuela de Física 6, no. 1 (January 16, 2019): 9–24. http://dx.doi.org/10.5377/ref.v6i1.7016.

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The free translational dynamics of an n-body quantum system has many applications, e.g. in molecular and nuclei systems, where it is common to classify the degrees of freedom of the system in 3 rotational and 3n - 6 shape coordinates. It is known that there exists an interaction between the shape and orientation degrees of freedom. In particular, changes of the shape could induce an orientation change. In this work, it is shown a rotating quantum system which does not deform its shape probability density and with vanishing angular momentum. The orientation change is monitored with a localized orientation wavefunction. We characterize the localized wavefunctions and study their evolution under a rigid rotor-like Hamiltonian, concluding that this kind of wavefunctions may rotate by their own.

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Navarro, M. D., M. D. Meseguer, I. Ordeig, and J. Lluch. "Milling angular references and process parameters on fiber reinforced plastics." IOP Conference Series: Materials Science and Engineering 1193, no. 1 (October 1, 2021): 012004. http://dx.doi.org/10.1088/1757-899x/1193/1/012004.

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Abstract Machining of fiber-reinforced composites produces delamination in the workpiece. In bidirectional long fiber fabric reinforced composites, delamination depends on different parameters. In this work, two parameters are studied: fiber orientation angle respect to machining direction and the distance of the warp yarn from the trimmed edge until the next dip below the crossing fill. This work defines angles relating fiber orientation with cutting and feed movements and their relations in a robust way, being applied to edge trimming and grooving operations. On the other hand, for Type II delamination, three different kinds of delamination (constant, uniform pattern variation and random) are studied taking into account fiber orientation, wick size and the fiber orientation angle respect to machining direction.

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Wright, Stuart I., Jay A. Basinger, and Matthew M. Nowell. "Angular Precision of Automated Electron Backscatter Diffraction Measurements." Materials Science Forum 702-703 (December 2011): 548–53. http://dx.doi.org/10.4028/www.scientific.net/msf.702-703.548.

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Electron backscatter diffraction (EBSD) has become the preferred technique for characterizing the crystallographic orientation of individual grains in polycrystalline microstructures due to its ability to rapidly measure orientations at specific points in the microstructure at resolutions of approximately 20-50nm depending on the capabilities of the scanning electron microscope (SEM) and on the material being characterized. Various authors have studied the angular resolution of the orientations measured using automated EBSD. These studies have stated values ranging from approximately 0.1° to 2° [1-6]. Various factors influence the angular resolution achievable. The two primary factors are the accuracy of the detection of the bands in the EBSD patterns and the accuracy of the pattern center (PC) calibration. The band detection is commonly done using the Hough transform. The effect of varying the Hough transform parameters in order to optimize speed has been explored in a previous work [6]. The present work builds upon the earlier work but with the focus towards achieving the best angular resolution possible regardless of speed. This work first details the methodology used to characterize the angular precision then reports on various approaches to optimizing parameters to improve precision.

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Molodenkov, A. V., Ya G. Sapunkov, and T. V. Molodenkova. "The New Analytical Algorithm for Determining the Strapdown INS Orientation." Mekhatronika, Avtomatizatsiya, Upravlenie 20, no. 10 (October 10, 2019): 624–28. http://dx.doi.org/10.17587/mau.20.624-628.

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The analytical solution of an approximate (truncated) equation for the vector of a rigid body finite rotation has made it possible to solve the problem of determining the quaternion of orientation of a rigid body for an arbitrary angular velocity and small angle of rotation of a rigid body with the help of quadratures. Proceeding from this solution, the following approach to the construction of the new analytical algorithm for computation of a rigid body orientation with the use of strapdown INS is proposed: 1) By the set components of the angular velocity of a rigid body on the basis of mutually — unambiguous changes of the variables at each time point, a new angular velocity of a rigid body is calculated; 2) Using the new angular velocity and the initial position of a rigid body, with the help of the quadratures we find the exact solution of an approximate linear equation for the vector of a rigid body finite rotation with a zero initial condition; 3) The value of the quaternion orientation of a rigid body (strapdown INS) is determined by the vector of finite rotation. During construction of the algorithm for strapdown INS orientation at each subsequent step the change of the variables takes into account the previous step of the algorithm in such a way that each time the initial value of the vector of finite rotation of a rigid body will be equal to zero. Since the proposed algorithm for the analytical solution of the approximate linear equation for the vector of finite rotation is exact, it has a regular character for all angular motions of a rigid body).

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Balaban, Carey D., David M. McGee, Jianxun Zhou, and Charles A. Scudder. "Responses of Primate Caudal Parabrachial Nucleus and Kölliker-Fuse Nucleus Neurons to Whole Body Rotation." Journal of Neurophysiology 88, no. 6 (December 1, 2002): 3175–93. http://dx.doi.org/10.1152/jn.00499.2002.

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The caudal aspect of the parabrachial (PBN) and Kölliker-Fuse (KF) nuclei receive vestibular nuclear and visceral afferent information and are connected reciprocally with the spinal cord, hypothalamus, amygdala, and limbic cortex. Hence, they may be important sites of vestibulo-visceral integration, particularly for the development of affective responses to gravitoinertial challenges. Extracellular recordings were made from caudal PBN cells in three alert, adult female Macaca nemestrina through an implanted chamber. Sinusoidal and position trapezoid angular whole body rotation was delivered in yaw, roll, pitch, and vertical semicircular canal planes. Sites were confirmed histologically. Units that responded during rotation were located in lateral and medial PBN and KF caudal to the trochlear nerve at sites that were confirmed anatomically to receive superior vestibular nucleus afferents. Responses to whole-body angular rotation were modeled as a sum of three signals: angular velocity, a leaky integration of angular velocity, and vertical position. All neurons displayed angular velocity and integrated angular velocity sensitivity, but only 60% of the neurons were position-sensitive. These responses to vertical rotation could display symmetric, asymmetric, or fully rectified cosinusoidal spatial tuning about a best orientation in different cells. The spatial properties of velocity and integrated velocity and position responses were independent for all position-sensitive neurons; the angular velocity and integrated angular velocity signals showed independent spatial tuning in the position-insensitive neurons. Individual units showed one of three different orientations of their excitatory axis of velocity rotation sensitivity: vertical-plane-only responses, positive elevation responses (vertical plane plus ipsilateral yaw), and negative elevation axis responses (vertical plane plus negative yaw). The interactions between the velocity and integrated velocity components also produced variations in the temporal pattern of responses as a function of rotation direction. These findings are consistent with the hypothesis that a vestibulorecipient region of the PBN and KF integrates signals from the vestibular nuclei and relay information about changes in whole-body orientation to pathways that produce homeostatic and affective responses.

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Rekveldt, M. Theo, Wicher Kraan, and Thomas Keller. "High-resolution diffraction using Larmor precession of polarized neutrons." Journal of Applied Crystallography 35, no. 1 (January 22, 2002): 28–33. http://dx.doi.org/10.1107/s0021889801017812.

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A new Larmor precession device, consisting of two separate precession modules, is introduced. It operates as a high-resolution neutron diffractometer, without the need for a highly collimated beam, necessary in conventional high-resolution neutron diffraction. The same instrument operates in different modes as an effective small-angle scattering device or accurately determines the line profile, the lattice plane orientation or the angular spread in crystal orientations. A dramatic intensity gain can be obtained in all applications discussed, compared with the conventional analogues, owing to the possibility to use a relaxed wavelength and angular resolution. Experiments in the high-resolution diffraction mode on Si and Al are discussed.

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Ozgoren, M. Kemal. "Comparative study of attitude control methods based on Euler angles, quaternions, angle–axis pairs and orientation matrices." Transactions of the Institute of Measurement and Control 41, no. 5 (June 20, 2018): 1189–206. http://dx.doi.org/10.1177/0142331218773519.

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This paper presents a comparative study about the attitude control methods based on four commonly used error indicators, namely the triad of 3-2-1 deviational Euler angles, the error quaternion, the deviational angle–axis pair and the orientation error matrix. These error indicators are used here with the same backstepping control law to have a common basis of comparison. This control law makes the controller track a restoring angular velocity generated here specifically for each error indicator. This comparative study shows that all these error indicators can be used satisfactorily even in the critical orientations associated with them by taking special measures. For the deviational Euler angle triad, a critical orientation is a singularity, at which the angles become indefinite. Unless the vehicle is stationary, this indefiniteness is resolved here by applying L’Hopital’s Rule on the angular velocity information. The Euler angle triad has also a multiplicity problem. It is solved here by using the novel criterion of minimal deviation angles. For the other error indicators, a critical orientation is an antipodal orientation, which is opposite to the desired one. In an antipodal orientation, the error quaternion and the deviational angle–axis pair cannot be determined through the customary formulas. They are determined here by using the novel specially introduced formulas. Besides, they may suffer from the unwinding phenomenon in an ordinary orientation. This phenomenon is prevented here by keeping the scalar part of the error quaternion non-negative and the deviation angle between 0° and 180°. For the orientation error matrix, a stationary and undisturbed antipodal orientation is an unstable equilibrium, in which the ordinary backstepping control law becomes ineffective for driving the system into action. This problem is solved here by adding an extra term to the ordinary backstepping control law.

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DiBenedetto, Michelle H., and Nicholas T. Ouellette. "Preferential orientation of spheroidal particles in wavy flow." Journal of Fluid Mechanics 856 (October 12, 2018): 850–69. http://dx.doi.org/10.1017/jfm.2018.738.

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We report a theoretical study of the angular dynamics of small, non-inertial spheroidal particles in a linear wave field. We recover the observation recently reported by DiBenedetto et al. (J. Fluid Mech., vol. 837, 2018, pp. 320–340) that the orientation of these spheroids tends to a stable limit cycle consisting of a preferred value with a superimposed oscillation. We show that this behaviour is a consequence of finite wave amplitude and is the angular analogue of Stokes drift. We derive expressions for both the preferred orientation of the particles, which depends only on particle shape, and the amplitude of the oscillation about this preferred value, which additionally depends on the wave parameters and the depth of the particle in the water column.

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Guedry, F. E., A. H. Rupert, B. J. McGrath, and C. M. Qman. "The Dynamics of Spatial Orientation During Complex and Changing Linear and Angular Acceleration1." Journal of Vestibular Research 2, no. 4 (October 1, 1992): 259–83. http://dx.doi.org/10.3233/ves-1992-2402.

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The dynamics of spatial orientation perception were examined in a series of experiments in which a total of 43 subjects were passively exposed to various combinations of linear and angular acceleration during centrifuge runs. Perceptual effects during deceleration were much stronger than effects during acceleration. The dynamics of spatial orientation perception differed substantially from changes in the vestibulo-ocular reflex (VOR). VOR was fairly well predicted by a current model, but our experiments revealed perceived change in attitude (roll, pitch, yaw tilt position in space) and perceived angular velocity in space that was not reflected by parallel changes in the plane or magnitude of the VOR. This series of experiments establishes several facts concerning spatial orientation perception beyond the predictive domain of any current model. New concepts are needed and several are suggested to deal with changing reactions to complex combinations of linear and angular accelerations.

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Boeyens, Jan C. A. "Angular Momentum in Chemistry." Zeitschrift für Naturforschung B 62, no. 3 (March 1, 2007): 373–85. http://dx.doi.org/10.1515/znb-2007-0311.

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Noting that current chemical theory is based almost exclusively on electronic energy and spin variables the equal importance of orbital angular momentum is explored in this paper. From its classical definition the angular momentum of electrons in an atom is shown to obey Laplace’s equation, which automatically leads to discrete values in terms of spherical harmonics. This analysis assumes a continuous distribution of electronic charge, which resembles a fluid at equilibrium. It serves to elucidate the success and failure of Bohr’s conjecture and the origin of wave-particle duality. Applied to atoms, minimization of orbital angular momentum leads to Hund’s rules. The orientation of angular momenta in lower-symmetry molecular environments follows from the well-known Jahn-Teller theorem.

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Lafrance, Claude-Paul, Anne Nabet, Robert E. Prud'homme, and Michel Pézolet. "On the relationship between the order parameter and the shape of orientation distributions." Canadian Journal of Chemistry 73, no. 9 (September 1, 1995): 1497–505. http://dx.doi.org/10.1139/v95-185.

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The molecular orientation is generally expressed by an "order parameter," [Formula: see text] which depends on both the angular position and the shape of the orientation distribution. This parameter is an average made over all orientations of the structural units studied in a sample and, consequently, a given [Formula: see text] value can correspond to different orientation distributions. In this article, model distributions are used to show the relationship between the shape, width, and angular position of the center of the orientation distribution on the [Formula: see text] coefficient, for the case where the distribution of the molecular chains exhibits cylindrical symmetry with respect to the reference direction. A significant difference is observed between the order parameters calculated for distributions of Gaussian and Lorentzian shapes with similar width at half-height. The variation of the [Formula: see text] coefficient as a function of the width at half-height, W1/2, and of the position of the center of the distribution, θC, is analyzed. Figures showing the range of W1/2–θC coordinates that can correspond to a given [Formula: see text] value are presented. As an example, the influence on the order parameter of the disorder between the different domains of phospholipid samples (mosaic spread) and of the conformational disorder in the acyl chains of these molecules is also studied. This example permits the evaluation of the magnitude of the errors that can be introduced in calculations of the tilt angle of the molecular chains in the case of distributions of finite widths or of bimodal character. Keywords: orientation, orientation function, phospholipid bilayers, conformational disorder, mosaic spread.

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Matsunaga, D., Y. Imai, C. Wagner, and T. Ishikawa. "Reorientation of a single red blood cell during sedimentation." Journal of Fluid Mechanics 806 (September 29, 2016): 102–28. http://dx.doi.org/10.1017/jfm.2016.601.

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The reorientation phenomenon of a single red blood cell during sedimentation is simulated using the boundary element method. The cell settles downwards due to a density difference between the internal and external fluids, and it changes orientation toward a vertical orientation regardless of Bond number or viscosity ratio. The reorientation phenomenon is explained by a shape asymmetry caused by the gravitational driving force, and the shape asymmetry increases almost linearly with the Bond number. When velocities are normalised by the driving force, settling/drifting velocities are weak functions of the Bond number and the viscosity ratio, while the angular velocity of the reorientation drastically changes with these parameters: the angular velocity is smaller for lower Bond number or higher viscosity ratio. As a consequence, trajectories of the sedimentation are also affected by the angular velocity, and blood cells with slower reorientation travel longer distances in the drifting direction. We also explain the mechanism of the reorientation using an asymmetric dumbbell. From the analysis, we show that the magnitude of the angular velocity is explained by two main factors: the shape asymmetry and the instantaneous orientation angle.

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Neagoe, Mircea, Maria M. Vatasescu, Radu G. Saulescu, and Nora Creanga. "On New High Performance Systems with Linear Actuators for Diurnal Orientation of PV Platforms." Applied Mechanics and Materials 162 (March 2012): 214–23. http://dx.doi.org/10.4028/www.scientific.net/amm.162.214.

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The paper presents new mechatronic systems used to perform the diurnal orientation of photovoltaic (PV) platforms, aiming to achieve high angular strokes and also low cost, high precision, constructive simplicity and relative low pressure angles. Starting from the disadvantages of the existing tracking mechanism identified in the literature (patents, scientific articles, market documentation, etc.), new high performance linkages and gear mechanisms driven by linear actuators are proposed in the paper. Hence, four new tracking mechanisms, achieving high angular strokes (over 180o), are described: a) quadrilateral type, b) rhombus type, c) slider-crank type, and d) linkage with gears type. These mechanisms are designed especially for concentrating PV systems, which require high orientation precision on the entire angular stroke.

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Journal articles on the topic 'Angular orientation'

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