IRA++: Distributed Incremental Rotation Averaging

2021 ◽  
pp. 1-1
Author(s):  
Xiang Gao ◽  
Lingjie Zhu ◽  
Hainan Cui ◽  
Zexiao Xie ◽  
Shuhan Shen
Keyword(s):  
Incremental Rotation

Visual Mental Rotation: Different Processes Used by Pilots

1992 ◽  
Vol 36 (18) ◽  
pp. 1368-1372
Author(s):  
Itiel E. Dror
Keyword(s):  
Mental Rotation ◽  
Single Step ◽  
The Other ◽  
Angular Rotation ◽  
Small Perturbations ◽  
Starting Position ◽  
Control Subjects ◽  
Complex Stimuli ◽  
And Control ◽  
Incremental Rotation

Air Force pilots and control subjects were tested on a visual “mental rotation” task. Nine of the 16 pilots, as well as all of the 16 control subjects, required more time to rotate greater angular distances. The performance of the other 7 pilots was unique: their response time did not increase with greater angular rotations. The results suggest that visual mental rotation can be accomplished by at least two different processes. One process involves incremental object rotations in a multi-step mapping –like an actual physical rotation of an object– going through intermediate stages. This process requires more time to rotate greater angular distances. The other process involves direct translation in a single-step mapping. In this process, the starting position transforms into the final position in one mapping without any intermediate steps, and thus does not require more time to rotate greater angular rotation. The lack of intermediate stages, which may allow small perturbations in location to be corrected, affects the accuracy of this process; this is particularly apparent when more complex stimuli are rotated. The pilots who did not show incremental rotation effects had different and distinct error patterns, their errors increased when rotating the more complex stimuli.

Rotation Axes of the Head During Positioning, Head Shaking, and Locomotion

2007 ◽  
Vol 98 (5) ◽  
pp. 3095-3108 ◽  
Author(s):  
Mikhail Kunin ◽  
Yasuhiro Osaki ◽  
Bernard Cohen ◽  
Theodore Raphan
Keyword(s):  
Rotation Axis ◽  
Human Subjects ◽  
Head Orientation ◽  
Pivot Point ◽  
Rotation Axes ◽  
Static Head ◽  
Head Positions ◽  
Occipital Condyles ◽  
Digital Human ◽  
Incremental Rotation

Static head orientations obey Donders’ law and are postulated to be rotations constrained by a Fick gimbal. Head oscillations can be voluntary or generated during natural locomotion. Whether the rotation axes of the voluntary oscillations or during locomotion are constrained by the same gimbal is unknown and is the subject of this study. Head orientation was monitored with an Optotrak (Northern Digital). Human subjects viewed visual targets wearing pin-hole goggles to achieve static head positions with the eyes centered in the orbit. Incremental rotation axes were determined for pitch and yaw by computing the velocity vectors during head oscillation and during locomotion at 1.5 m/s on a treadmill. Static head orientation could be described by a generalization of the Fick gimbal by having the axis of the second rotation rotate by a fraction, k, of the angle of the first rotation without a third rotation. We have designated this as a k-gimbal system. Incremental rotation axes for both pitch and yaw oscillations were functions of the pitch but not the yaw head positions. The pivot point for head oscillations was close to the midpoint of the interaural line. During locomotion, however, the pivot point was considerably lower. These findings are well explained by an implementation of the k-gimbal model, which has a rotation axis superimposed on a Fick-gimbal system. This could be realized physiologically by the head interface with the dens and occipital condyles during head oscillation with a contribution of the lower spine to pitch during locomotion.

Natural Convection in the Inclined, Cranked Thermosyphon

1993 ◽  
Vol 115 (1) ◽  
pp. 166-172 ◽  
Author(s):  
G. S. H. Lock ◽  
J. Fu
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Vertical Plane ◽  
Horizontal Axis ◽  
Transfer Rates ◽  
Axis Parallel ◽  
Incremental Rotation

Consideration is given to natural convection in a cranked, tubular thermosyphon oriented in various ways with respect to the vertical. Experiments on a small-bore, water-filled tube are used to investigate three orientational effects: by tilting in a vertical plane containing the tubes; by incremental rotation about the axis of the horizontal connecting tube; and by incremental rotation about a horizontal axis parallel to the thermosyphon tube axes. The results reveal similarities between the cranked and linear thermosyphons. In general, horizontal alignments are found to produce higher heat transfer rates.

scholarly journals Optically ambidextrous circularly polarized reflection from the chiral cuticle of the scarab beetle Chrysina resplendens

2017 ◽  
Vol 14 (131) ◽  
pp. 20170129 ◽  
Author(s):  
Ewan D. Finlayson ◽  
Luke T. McDonald ◽  
Pete Vukusic
Keyword(s):  
Polarized Light ◽  
Scattering Matrix ◽  
Scarab Beetle ◽  
Optical Behaviour ◽  
Structural Morphology ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Left Handed ◽  
Optical Effects ◽  
Incremental Rotation

The evolution of structural colour mechanisms in biological systems has given rise to many interesting optical effects in animals and plants. The instance of the scarab beetle Chrysina resplendens is particularly distinctive. Its exoskeleton has a bright, golden appearance and reflects both right-handed and left-handed circularly polarized light concurrently. The chiral nanostructure responsible for these properties is a helicoid, in which birefringent dielectric planes are assembled with an incremental rotation. This study correlates details of the beetle's circularly polarized reflectance spectra directly with physical aspects of its structural morphology. Electron micrography is used to identify and measure the physical dimensions of the key constituent components. These include a chiral multilayer configuration comprising two chirped, left-handed helicoids that are separated by a birefringent retarder. A scattering matrix technique is used to simulate the system's optical behaviour in which the roles of each component of the morphological substructure are elucidated by calculation of the fields throughout its depth.

Incremental Rotation Averaging

2021 ◽  
Author(s):  
Xiang Gao ◽  
Lingjie Zhu ◽  
Zexiao Xie ◽  
Hongmin Liu ◽  
Shuhan Shen
Keyword(s):  
Incremental Rotation

Constrained finite rotations in dynamics of shells and Newmark implicit time‐stepping schemes

2005 ◽  
Vol 22 (5/6) ◽  
pp. 505-535 ◽  
Author(s):  
Boštjan Brank ◽  
Said Mamouri ◽  
Adnan Ibrahimbegović
Keyword(s):  
Design Methodology ◽  
Implicit Time ◽  
Conceptual Approach ◽  
Finite Rotations ◽  
Content Type ◽  
Time Stepping ◽  
Consistent Linearization ◽  
Rotation Parameters ◽  
Incremental Rotation

PurposeAims to address the issues pertaining to dynamics of constrained finite rotations as a follow‐up from previous considerations in statics.Design/methodology/approachA conceptual approach is taken.FindingsIn this work the corresponding version of the Newmark time‐stepping schemes for the dynamics of smooth shells employing constrained finite rotations is developed. Different possibilities to choose the constrained rotation parameters are discussed, with the special attention given to the preferred choice of the incremental rotation vector.Originality/valueThe pertinent details of consistent linearization, rotation updates and illustrative numerical simulations are supplied.

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