Rotational Orientation Research Articles

A Smartphone app for intensive care unit rotation Orientation.

Implication Statement
 The Department of Critical Care at Dalhousie University developed a smartphone app to improve the quality of learner orientation to the intensive care unit (ICU). The app increased satisfaction with orientation and was perceived as useful. It was ranked as the second most valued resource for orientation after other residents. There is potential to improve the experience of learners with this popular technology.

Influence of loading geometry and palm fibres’ orientation on modification of collapsible sand

A review of existing literature suggests that extensive numerical and experimental works have been conducted on modifying soils using randomly distributed fibres. However, the influence of different types of loading geometry and the effect of fibres on modification of sandy soil have not been reported yet. The main objective of the present study was to evaluate the influence of palm fibres’ orientation on the modification of collapsible sand using different types of loading, including constrained, axisymmetric, and plane strain simulation. A laboratory testing program, consisting of 95 tests, was performed using oedometer, direct shear, and triaxial tests. It was observed that the orientation of fibres in the specimens was approximately perpendicular to the direction of the applied compaction effort. The results of oedometer tests for measuring of the collapsibility potential revealed that addition of the fibre content had no significant effect in reducing the collapsibility potential. For the two mould sizes used in the direct shear tests, an increase in fibre content did not cause any changes in the shear strength parameters. In triaxial tests, the results indicated a significant enhancement in strength with increase in the fibre content. The rotation of the principal stress orientation during the shear stage of the tests played an important role in mobilising the tensile strength of the fibres. The results suggested that the effect of fibre orientation and loading geometry is strongly consistent for evaluating the modification of fibre-reinforced sand.

Full-automatic seed point selection and initialization for digital image correlation robust to large rotation and deformation

Accurate initial guess plays a key role to realize full-automatic digital image correlation (DIC) analysis, especially when large rotational deformation presents in deformed images. In this work, an efficient, robust and full-automatic initial guess approach combining the speeded-up robust features (SURF) algorithm and the reliability-guided displacement tracking (RGDT) strategy is proposed, which can not only automatically select and update seed point, but also can effectively deal with target images with large deformation and rotation. The scale- and rotation-invariant SURF algorithm can extract and match a certain number of feature points from two images even though the significant deformation and rotation present. The Euclidean distance and deformation information (including displacement and major orientation rotation angle) of the best-matched point are used to choose the seed point and determine its initial guess, respectively. Then, the RGDT strategy is then employed to continue the DIC analysis of rest calculation points. Compared with existing path-dependent initial guess using RGDT, the proposed method not only can automatically select seed points without manual intervention, but also can provide accurate initial value estimation for the deformed images in the presence of large rotation and/or deformation. Furthermore, it has evident efficiency advantages over existing path-independent initial guess methods based on SIFT and RANSAC. The robustness and effectiveness of the proposed method are validated by numerical simulation tests and real experiments.

Altering magnetic response of superconductors by rotation

It is generally believed that, at a certain temperature below the critical one, magnetic response of a superconductor (SC) is determined solely by its intrinsic properties. Here we show that the mechanical rotation of a SC can easily change the values of the critical fields at which the superconductivity is destroyed (type-1 SC) or the vortices penetrate into (exit from) the material (type-2 SC). This is due to a superposition of the Meissner current induced by the external field, and the spontaneous current on the surface of the SC induced by the mechanical rotation. As a result, the critical fields of a SC can be increased or decreased, depending on the geometrical form of the material and the relative orientation of rotation and the external field.

Strong toroidal magnetic fields required by quiescent X-ray emission of magnetars

Magnetars are neutron stars (NSs) with extreme magnetic fields of strength $5 \times 10^{13}$ - $10^{15}$ G. They exhibit transient, highly energetic events, such as short X-ray flashes, bursts and giant flares, all of which are powered by their enormous magnetic energy. Quiescent magnetars have X-ray luminosities between $10^{29}$ and $10^{35}$ erg/s, and are further classified as either persistent or transient magnetars. Their X-ray emission is modulated with the rotational period of the NS, with a typical relative amplitude (so-called pulsed fraction) between 10-58 per cent, implying that the surface temperature is significantly non-uniform despite the high thermal conductivity of the star's crust. Here, we present the first 3D magneto-thermal MHD simulations of magnetars with strong toroidal magnetic fields. We show that these models, combined with ray propagation in curved space-time, accurately describe the light-curves of most transient magnetars in quiescence and allow us to further constrain their rotational orientation. We find that the presence of a strong toroidal magnetic field explains the observed asymmetry in the surface temperature, and is the main cause of the strong modulation of thermal X-ray emission in quiescence.

Accuracy of EOS Imaging Technology in Comparison to Computed Tomography in the Assessment of Vertebral Rotational Orientation in Instrumented Spines in Adolescent Idiopathic Scoliosis.

Retrospective radiographic reliability study. The aim of this study was to assess the validity of EOS 3D imaging technology in the determination of vertebral rotations in the spine of patients with previous instrumentation. There is a lack of evidence on the accuracy of vertebral rotational measurement using EOS 3D morphological analysis in the instrumented spine. A retrospective review of 31 patients with adolescent idiopathic scoliosis (AIS) who underwent instrumented fusion and postoperative computed tomography (CT) scans of the spine was performed. Vertebral rotations of the apex vertebra, the uppermost (UIV) and lowermost (LIV) instrumented vertebra, the noninstrumented vertebra one level cranial to the UIV (UIV + 1) and one level caudal to LIV (LIV + 1) were determined using EOS 3D reconstruction. The vertebral rotation was also measured using reformatted CT axial images. Relative vertebral rotational difference (VRD) were calculated for UIV to apex, UIV + 1 to apex, LIV to apex, LIV + 1 to apex, UIV to LIV and UIV + 1 to LIV + 1. Paired t tests were used to compare the VRD measured using the two different imagining modalities. For values where P > 0.05, the Bland-Altman plot was used to assess the agreement between the measures. Interclass correlation (ICC) was used to determine interobserver and intraobserver reliabilities of EOS and CT measurements. EOS analysis of relative VRD was found to be significantly different from that of CT for UIV to apex (P = 0.006) and UIV + 1 to apex (P = 0.003). No significant differences were found for LIV to apex (P = 0.06), LIV + 1 to apex (P = 0.06), UIV to LIV (P = 0.59) and UIV + 1 to LIV + 1 (P = 0.64). However, Bland-Altman plots showed that agreement was poor, and variance was beyond acceptable. ICC showed good interobserver and good to very good intraobserver reliability for EOS. EOS 3D morphological analysis of VRD in the instrumented levels of the spine demonstrated significant difference and unacceptable variance in comparison to CT measurement.Level of Evidence: 4.

A Novel Anisotropic Failure Criterion With Dispersed Fiber Orientations for Aortic Tissues.

Accurate failure criteria play a fundamental role in biomechanical analyses of aortic wall rupture and dissection. Experimental investigations have demonstrated a significant difference of aortic wall strengths in the circumferential and axial directions. Therefore, the isotropic von Mises stress and maximum principal stress, commonly used in computational analysis of the aortic wall, are inadequate for modeling of anisotropic failure properties. In this study, we propose a novel stress-based anisotropic failure criterion with dispersed fiber orientations. In the new failure criterion, the overall failure metric is computed by using angular integration (AI) of failure metrics in all directions. Affine rotations of fiber orientations due to finite deformation are taken into account in an anisotropic hyperelastic constitutive model. To examine fitting capability of the failure criterion, a set of off-axis uniaxial tension tests were performed on aortic tissues of four porcine individuals and 18 human ascending thoracic aortic aneurysm (ATAA) patients. The dispersed fiber failure criterion demonstrates a good fitting capability with the off-axis testing data. Under simulated biaxial stress conditions, the dispersed fiber failure criterion predicts a smaller failure envelope comparing to those predicted by the traditional anisotropic criteria without fiber dispersion, which highlights the potentially important role of fiber dispersion in the failure of the aortic wall. Our results suggest that the deformation-dependent fiber orientations need to be considered when wall strength determined from uniaxial tests are used for in vivo biomechanical analysis. More investigations are needed to determine biaxial failure properties of the aortic wall.

Spatial ability differences between students with a math learning disability and their other normal colleagues

Purpose This study aims to investigate the differences in spatial ability between students with a math learning disability and their normal peers. Design/methodology/approach To investigate these differences two groups, (60 students with a math learning disability) and (60 normal students) from fifth grade with a mean age (10.6 years) were administered with spatial ability test along with an IQ test. Students with a math learning disability were chosen using measures of the following: math learning disability questionnaire developed from learning disability evaluation scale – renormed second edition (LDES-R2) (McCarney and Arthaud, 2007) and the Quick Neurological Screening Test (Mutti et al., 2012), in addition to their marks in formal math tests in school. Findings Comparison between the two groups in four aspects of spatial ability resulted in obvious differences in each aspect of spatial ability (spatial relations, mental rotation, spatial visualization and spatial orientation); these differences were clear, especially in mental rotation and spatial visualization. Originality/value This paper contributes to gain more insights into the characteristics of pupils with a math learning disability, the nature of spatial abilities and its effect on a math learning disability. Moreover, the results suggest spatial ability to be an important diagnose factor to distinguish and identify students with a math learning disability, and that spatial ability is strongly relevant to math achievement. The results have significant implications for success in the science, technology, engineering and mathematics domain.

Early Committed Clockwise Cell Chirality Upregulates Adipogenic Differentiation of Mesenchymal Stem Cells.

Cell chirality is observed with diverse forms and coordinates various left-right (LR) asymmetry in tissue morphogenesis. To give rise to such diversity, cell chirality may be coupled with cell differentiation. Here, using micropatterned human mesenchymal stem cells (hMSCs), an early committed clockwise (CW) cell chirality that can itself upregulate the adipogenic differentiation is reported. hMSC chirality enables a positively tilted chiral orientation on micropatterned stripes. When cultured as single cells on circular micropatterns, an anticlockwise (ACW)-biased nucleus rotation and swirling pattern of actin filament are observed. Interestingly, with adipogenic induction for 3-6 days, such chirality is reversed to negative chiral orientation and CW-biased rotation, which is earlier than the maturation of other differentiation markers, and consistently expressed in terminally differentiated adipocytes. Using latrunculin A (LatA), cytochalasin D (CD), and nocodazole (Noco) that forces a CW-biased actin filament and nucleus rotation resembling the early differentiated chirality upon adipogenic induction, an upregulation of adipogenic differentiation is found. The result demonstrates that the early differentiated chirality may serve as a mechanical precursor to engage the lineage commitment, suggesting a feedback mechanism of chiral actin in regulating cell differentiation and LR morphogenesis.

Circular motion of multiple nonholonomic robots under switching topology with ordinal ranking

This paper investigates the circular motion of a group of n(n ≥ 2) nonholonomic robots over time-varying communication networks. We aim to achieve a balanced circular motion centered at a location determined by each robot under the assumption that the global ranking of any robot is unknown. A back-stepping based controller is firstly designed to make all the robots rotate around a common center, the position of which is obtained through executing a consensus algorithm by each robot. Then, the maximum and minimum consensus algorithm and a distributed modified ordinal ranking algorithm are applied to set the rotation radius, angular velocity, and orientation parameters in a distributed manner such that all the robots can uniformly space on the common circle. At last, the effectiveness of the proposed algorithms is illustrated through a simulation example.

Flattening the Learning Curve: A Case-Based Video Orientation for a Subspeciality Residency Rotation.

To determine whether a clinically focused rotation orientation delivered through e-learning videos would be an effective method to improve residents' clinical knowledge and confidence. A pre-post study design evaluated for change in knowledge and confidence between a control and intervention group of residents assigned to outpatient pediatric endocrinology rotations at 2 residency programs from July 2017 to March 2019. The intervention group utilized the first morning of the rotation to complete the video curriculum designed to rapidly orient residents to common clinical management tasks in outpatient pediatric endocrinology. A total of 35 of 41 residents (85%) completed the study (control group: 18/19 [95%]; intervention group: 17/22 [77%]). Score increase from pretest to post-test was significantly higher for intervention group compared to control group (+24.7% ± 12.1 vs +5.8% ± 7.9, P < .0001). Confidence increases were significantly higher in the intervention group compared to control group in 3 of 5 topics. Two themes illustrated residents' perspectives of this e-learning curriculum: 1) increase in foundational clinical knowledge and 2) improvement in efficiency of learning and patient care. This clinically focused rotation orientation delivered through e-learning videos was an effective method to improve residents' clinical knowledge, without reliance on faculty to deliver this orientation throughout the academic year. Further studies should be pursued in various settings.

Oriented stability and its application in texture control

ABSTRACT Orientation rotation tendency with respect to target orientation in body-centred cubic (bcc) crystal is investigated under different rolling modes. Oriented stability is proposed to describe the rotation rate towards target orientation in contrast to conventional orientation stability. The oriented stability distribution in Euler space can clearly present how an orientation contributes to target orientation. Furthermore, statistical oriented stability is introduced to represent the overall rotation tendency by orientation density weighting. Taking typical λ fibre (<001>//ND, normal direction) as the target orientation, the oriented stability distribution under symmetric (SR) and asymmetric rolling (ASR) is calculated. The orientation regions in Euler space that rapidly and slowly converge to or diverge from target orientation are identified. By combining oriented stability and orientation flow, the routine map for texture control can be accurately designed by modifying initial texture and strain tensor.

Referencing the substitute anteroposterior line of the tibia improves rotational alignment of the tibial component in medial unicompartmental knee arthroplasty

BackgroundThere is no consensus regarding how best to determine the tibial rotational alignment in unicompartmental knee arthroplasty (UKA). The purpose of this study was to clarify whether using the substitute anteroposterior (sAP) line of the tibia, as has recently been proposed, can improve tibial rotation. MethodsThe study included 57 consecutive medial UKAs. From May 2015 to September 2016, 28 knees in 28 patients underwent UKA using the medial intercondylar ridge (MIR) line as the tibial anteroposterior (AP) reference (MIR group). From October 2016 to March 2018, 29 knees in 29 patients underwent UKA using the sAP line (sAP group). In both groups, the external rotation angle of the tibial component relative to a line perpendicular to the surgical epicondylar axis was measured using computed tomography-based three-dimensional preoperative planning software for TKA and UKA. ResultsThe mean external rotation angles of the tibial component in the MIR and sAP groups were 5.2° ± 8.5° (range, −12.4° to 20.8°) and 0.7° ± 3.2° (range, −6.0° to 7.4°), respectively (unpaired t test, P = 0.014). The variation in the external rotation angle of the tibial component was significantly smaller in the sAP group than in the MIR group (F test, P < 0.0001), as was the number of the outliers with more than ±5° error (Fisher's exact test, P < 0.0001). ConclusionsThe use of the sAP line as the AP reference could improve and stabilize the rotational orientation of the tibial component in UKA procedures.

Effect of initial texture on the {10–12} twinning variants selection mechanism in AZ31 magnesium alloy

The influence of the initial texture of the {10–12} twinning variants selection mechanism of the magnesium alloy was investigated using the compression test, the EBSD technology, the trace method, the orientation rotation method, and the Schmid’s law. Results show that various {10–12} twin patterns are observed in the AZ31 E90 sample subjected to compression. In the multi-twins inside a grain pattern, the high Schmid factor (SF) variant is activated first to coordinate the externally imposed strain, and the ortho-position (OP) variant with the best strain compatibility is activated. Typical case of paired twins in two neighboring grains usually have high SF, and the activation of corresponding variants follows the Schmid’s law. When E45 sample is compressed, the of a pair of relative variants among the six twin variants in the crystal is very large and favorable for local strong basal texture formed by the two adjacent grains for the twin-transfer phenomenon. When E0 sample is compressed, the activation of the corresponding variants follows the Schmid’s law and is linked to the stress fluctuation at the grain boundary.

Spatial reasoning, mathematics, and gender: Do spatial constructs differ in their contribution to performance?

The role of gender in both spatial and mathematics performance has been extensively studied separately, with a male advantage often found in spatial tasks and mathematics from adolescence. Spatial reasoning is consistently linked to mathematics proficiency, yet despite this, little research has investigated the role of spatial orientation and gender in the relationship between spatial reasoning and mathematics. In the present study, three spatial reasoning constructs (mental rotation, spatial visualization, and spatial orientation) were examined for their unique contributions to mathematics performance in two samples (Study 1: grade 5; Study 2: grade 8). In light of the emerging gender gap in mathematics as children develop, these relationships were explored as a function of gender. Eighty-four fifth-grade students participated in Study 1 (43 females, 41 males; mean age=11.19years). Nine hundred and three eighth-grade students participated in Study 2 (498 females, 405 males; mean age=13.83years). The three spatial reasoning constructs (mental rotation, spatial visualization, and spatial orientation) were examined for their unique contributions to mathematics performance for females and males in general and across different mathematical content (geometry-measurement and number sense). Spatial factors accounted for 51% of the variance in math scores in Study 1 (grade 5) and 32% of the variance in math scores in Study 2 (grade 8). In both studies, spatial factors predicted a larger proportion of variance in geometry-measurement than for number sense. Spatial orientation was found to be a unique contributor in all mathematics models, object-based spatial skills (mental rotation and spatial visualization) varied in their contribution to math performance depending on mathematics content and gender. The present work highlights the unique contribution of spatial orientation in the spatial-mathematics relationship and provides insights into the nature of gender differences in mathematical problem-solving as a function of spatial reasoning and mathematics content.

Forces on buildings with openings and orientation in a steady post-tsunami free-surface flow

Steady free-surface flows around buildings occurring during flood or tsunami events can produce major damages and a quantification of the post-peak forces is essential for safety and resilience of coastal structures. The loading process is highly affected by the flow Froude number and the drag coefficient, commonly defined for highly subcritical flows, while field observations of tsunami flows reported Froude numbers close to one, visually appearing as a choked regime. The present experimental study addresses the hydrodynamic forces on emerging buildings in a subcritical choked regime, focusing on the effect of openings and orientation. Laboratory experiments indicated a substantial difference in flow depths between the up- and downstream side of the building for increasing Froude numbers. The presence of openings induced a flow through the building lowering the difference in flow depth, limiting the effect of the hydrostatic component of the loading process. The formulation of an empirical resistance coefficient CR allowed a combination of both form drag and hydrostatic forces. Whilst for impervious buildings CR was consistent with reference studies, for buildings with openings CR was directly dependent upon porosity. Contrarily to the unsteady flow conditions, results showed that the sidewalls also played a role in the loading process. Buildings with a rotated orientation resulted in slightly larger surfaces exposed to the flow and larger horizontal forces. Nevertheless, these were applied at lower cantilever arms, thus reducing the tilting moment. Altogether, this study provides experimentally-derived parameters that will support hydraulic engineers in the design of coastal structures.

A New Method for Measuring the Rotational Angles of a Precision Spherical Joint Using Eddy Current Sensors.

Precision spherical joint is a spherical motion pair that can realize rotation with three degrees of freedom. This joint is widely used in robots, parallel mechanisms, and high-end medical equipment, as well as in aerospace and other fields. However, the rotation orientation and angle cannot be determined when the joint is in passive motion. The real-time determination of the rotation orientation and angle is crucial to the improvement of the motion control accuracy of the equipment where the joint is installed in. In this study, a new measurement method that utilizes eddy current sensors is proposed to identify the special features of the joint ball and realize angle measurements indirectly. The basic idea is to manufacture the specific shape features on the ball without affecting its movement accuracy and mechanical performance. An eddy current sensor array is distributed in the ball socket. When the ball head rotates, the features on the ball opposite to the sensor, as well as the output signal of every eddy current sensor, change. The measurement model that establishes the relationship between the output signal of the eddy current sensor array and the rotation direction and angle of the ball head is constructed by learning and training an artificial neural network. A prototype is developed using the proposed scheme, and the model simulation and feasibility experiment are subsequently performed. Results show that the root mean square angular error of a single axis within a range of ±14° is approximately 20 min, which suggests the feasibility of the proposed method.

Morphology control of single-crystal InSb nanostructures by tuning the growth parameters

Research interest in indium antimonide (InSb) has increased significantly in recent years owing to its intrinsic properties and the consequent opportunities to implement next-generation quantum devices. Hence, the precise, reproducible control over morphology and crystalline quality becomes of paramount importance for a practical quantum-device technology. Here, we investigate the growth of InSb nanostructures with different morphologies on InAs stems without pre-growth efforts (patterning). InSb nanostructures such as nanowires (1D), nanoflags (2D) and nanocubes (3D) have been realized by means of Au-assisted chemical beam epitaxy by tailoring the growth parameters like growth temperature, precursor fluxes, sample rotation and substrate orientation. Through morphological and crystallographic characterization, all the as-grown InSb 2D nanostructures are found to be single-crystalline with zinc blende structure, free from any defects such as stacking faults and twin planes. The existence of two families of 2D nanostructures, characterised by an aperture angle at the base of 145° and 160°, is observed and modelled. This study provides useful guidelines for the controlled growth of high-quality InSb nanostructures with different shape.

Experimental and Numerical Investigation of Micro/Mini Channel Flow-Boiling Heat Transfer with Non-Uniform Circumferential Heat Fluxes at Different Rotational Orientations

Flow-boiling of Perfluorohexane (FC-72) in horizontal micro/mini channels was investigated experimentally and numerically at different rotational orientations in terms of gravity. One-sided uniform channel heating was considered experimentally for rotational angles ranging from 0° (heating from below) to 180° (heating from above) in increments of 30°. The micro/mini channel had a high aspect ratio of 10 (5 mm x 0.5 mm) and a hydraulic diameter of 909 μm. In-channel flow visualisations were recorded and heat transfer coefficients were determined for mass fluxes of 10, 20 and 40 kg/m2s at a saturation temperature of 56 °C. Suitable heat fluxes were applied to span the onset of nucleate boiling to near dry-out conditions within the channel. It was found that the rotational angle had a significant influence on the heat transfer performance due to its influence on bubble detachment. Bottom-heated cases (0° orientation) resulted in local heat transfer coefficients that were up to 201% higher than for any other rotational orientation. Channel orientations of 60° (slanted heating surface) and 90° (heating from the side) generally produced the lowest local heat transfer coefficients. Insight into the influence of the gravitational orientation on single-bubble growth within the nucleation and detachment region was obtained via two- and three-dimensional numerical simulations. Bubble behaviour after detachment and its effect on heat transfer were also investigated transiently until detachment. The numerical simulations mirrored the experimental trends and it was found that the presence of growing bubbles interrupted the velocity streamlines and the thermal boundary layer downstream of the nucleation site.

Aerodynamic Interactions of Quadrotor Configurations

An advanced potential flow method is used to study the aerodynamic interactions between small rotors of quadrotor configurations and the impact on the overall flight performance. The aerodynamic analysis method is validated by comparing the thrust and power predictions of isolated rotors in hover and forward flight with experimental results. The aerodynamic model was next extended to consider the interactions of several rotors of various quadrotor configurations. Compared with an independent rotor, the interaction of multiple, closely located rotors increases the power requirements of the vehicle and causes a loss of thrust. For diamond configurations, the rotation direction of the lead rotors impacts the thrusts of the midrotors and, subsequently, the overall vehicle rolling moment. For square configurations, slightly higher total thrusts and slightly greater tendencies to pitch up are observed when the retreating blades of the lead rotors move back along the vehicle centerline than for the reversed rotational orientations. The diamond configuration exhibits up to 3.5% higher rotor efficiency and a lesser tendency to pitch up with increasing forward speed than the square configuration.