3D Displacement Research Articles

High-precision atomic-scale strain mapping of nanoparticles from STEM images

Strain is a crucial factor that influences the physicochemical properties of nanoparticles. Being able to precisely measure strain is important in understanding the intrinsic mechanism of the enhanced performance of nanoparticles. Techniques that have been developed for strain analysis using scanning transmission electron microscopy (STEM) images can be categorized into diffraction-based method and imaging-based method. Here, using image simulation techniques, it is found that the measured two-dimensional (2D) displacements from annular dark field (ADF) STEM images of a nanoparticle are a good approximation to a projection of the actual three-dimensional (3D) displacements. A methodology for deformation analysis is presented which is based on the detection of atomic columns from atomic-resolution STEM images in real space. Elastic deformation parameters such as strain are usually defined on the basis of a continuum of deformation. The appropriateness of various deformation parameters for atomic-scale investigation on STEM images is explored and a method for determining these is presented. We found that the local lattice parameter and principal strain components are the most physically meaningful parameters to express the materials distortion behaviour. Apart from the local lattice parameter, the other deformation parameters such as normal strains, shear strains and displacements, heavily rely on the choice of reference lattice. It is also found that different reference grids add a series of uniform offsets to these strain variations. Finally, this approach is applied to a PtCo3 bimetallic nanoparticle to quantify its deformation behaviour.

Geomechanical Model for Frictional Contacting and Intersecting Fracture Networks: An Improved 3D Displacement Discontinuity Method

Summary The displacement discontinuity method (DDM) is widely used in large-scale engineering problems, such as hydraulic fracturing stimulation in unconventional reservoirs and enhanced geothermal systems, due to its convenient calculation and high precision. Although the 3D-DDM based on triangular elements can more accurately describe intrinsically geometric characteristics of artificial/natural fractures, due to the disadvantage of constant DDM, it will still produce large errors when calculating frictional contacting, close-spacing, and intersecting fractures, which greatly limits the universality of DDM in complex fracture networks. To the best of the authors’ knowledge, few DDM-based models are capable of tackling partially contacting fracture networks with arbitrary intersecting angles. In this paper, we propose a more efficient 3D-DDM algorithm via integrating the analytical solution, the 20-point Gaussian quadrature formula for standard triangles (GQSTS) integration algorithm, and the adaptive Gaussian-Kronrod integration algorithm. Then, combining the “local mesh refinement” grid, the Mohr-Coulomb correction for negative fracture aperture, and two rough fracture deletion strategies, the optimized 3D-DDM algorithm with broader versatility is established. All optimization measures are validated by the relevant fracture model. In the optimized 3D-DDM algorithm, (1) the “local mesh refinement” technique effectively improves the calculation accuracy of intersecting fractures; (2) the adaptive Gaussian-Kronrod integration algorithm not only improves the integration accuracy of high oscillation functions but is also 50% faster than the traditional Gaussian integration algorithm; (3) the Mohr-Coulomb criterion serves as a rigorous constraint for frictional contacting fractures to avoid the occurrence of negative fracture aperture; and (4) using the rough “deep deletion” or “shallow deletion” strategy to replace the ultrahigh-quality mesh generation can more conveniently maintain the accuracy of the complex fractures model. This optimized 3D-DDM algorithm may serve as a basis for simulating nonplanar 3D fracture swarms’ evolution, allowing for frictional contacting, closespacing, and intersecting fractures.

Quantification of the heterogeneous effect of static and dynamic perivascular structures on patient-specific local aortic wall mechanics using inverse finite element modeling and DENSE MRI

Recent studies have highlighted the relevance of perivascular interactions on aortic wall mechanics. Most of the approaches assume static perivascular structures; however, the beating heart dynamically displaces the neighboring aorta. We develop a model to account for the effect of periaortic interactions due to static and dynamic structures by prescribing a moving elastic foundation boundary condition (EFBC) embedded into an inverse finite element algorithm using in vivo displacements from 2D displacement encoding with stimulated echoes (DENSE) MRI as target data. We applied this method at three different locations of interest, the distal aortic arch (DAA), descending thoracic aorta (DTA), and infrarenal abdominal aorta (IAA) for a total of 27 cases in healthy humans. The model reproduces the target diastole-to-systole deformation and bulk displacement of the aortic wall with median displacement errors below 0.5mm. The EFBC showed good agreement with the location of anatomical features and was consistent among individuals of similar characteristics. Results show that an energy source acting on the adventitia is required to reproduce the displacements measured at the vicinity of the heart, but not at the abdomen. The average adventitial load as a percentage of the luminal pulse-pressure was found to increase with age and to decrease along the descending aorta, from 61% at the DAA to 37% at the DTA, and 30% at the IAA. This approach offers a patient-specific method to estimate in vivo adventitial loads and aortic wall stiffness, which can bring a better understanding of normal and pathological in vivo aortic function.

Self-supervised Monocular Depth Estimation with 3D Displacement Module for Laparoscopic Images.

We present a novel self-supervised training framework with 3D displacement (3DD) module for accurately estimating per-pixel depth maps from single laparoscopic images. Recently, several self-supervised learning based monocular depth estimation models have achieved good results on the KITTI dataset, under the hypothesis that the camera is dynamic and the objects are stationary, however this hypothesis is often reversed in the surgical setting (laparoscope is stationary, the surgical instruments and tissues are dynamic). Therefore, a 3DD module is proposed to establish the relation between frames instead of ego-motion estimation. In the 3DD module, a convolutional neural network (CNN) analyses source and target frames to predict the 3D displacement of a 3D point cloud from a target frame to a source frame in the coordinates of the camera. Since it is difficult to constrain the depth displacement from two 2D images, a novel depth consistency module is proposed to maintain depth consistency between displacement-updated depth and model-estimated depth to constrain 3D displacement effectively. Our proposed method achieves remarkable performance for monocular depth estimation on the Hamlyn surgical dataset and acquired ground truth depth maps, outperforming monodepth, monodepth2 and packnet models.

Two-dimensional displacement sensors with angstrom-scale resolution based on optical slot antenna arrays

Optical displacement sensing with high resolution and noncontact detection plays an important role in nanometrology, nanofabrication, and super-resolution microscopy. However, displacement sensing along an arbitrary direction in a two-dimensional (2D) plane with angstrom-level precision remains challenging. Here, we propose a 2D displacement sensor composed of eight optical slot antennas. A tightly focused laser beam is illuminated upon the antennas. The amplitudes and phases of the output radiation of the antennas are controlled by geometries. The intensity distribution of the output far-field radiation, which strongly depends on the relative position between the focal spot of the incident light and the antennas, was used to retrieve the 2D coordinates of any location in a plane. A resolution as high as 0.88 nm was obtained. We also show a method for improving displacement sensitivity by designing the destructive interference among the radiation of the antennas. The angstrom-scale resolution and arbitrary point localization, along with the nanoscale size, pave the way for the development of high-performance sensing, integrated photonic circuits, and on-chip signal processing.

Experimental validation of pore-scale models for gas diffusion layers

Pore-scale modeling developed over the past decades has become a powerful method to evaluate the effective transport properties of porous electrodes. Experimental verification for such a method is crucial to confirm the method's validity. In this study, experimental data of gas diffusion layer (GDL) are compared with results of pore-scale modeling. GDL microstructures are scanned and reconstructed by X-ray computed tomography. Explicit dynamic simulations based on the finite element method are performed on these reconstructed models to reveal the 3D displacement of the microstructure during compression. Over the deformed models, the effective diffusivity, thermal and electrical conductivities are then computed using a pore-scale model code. It is found that, as the compression ratio increases to 30%, the fiber displacement increases obviously with significant anisotropy, and the fibers gradually squeeze into nearby pores located in the adjacent layers inside GDL. The effective diffusivity and permeability decrease by about 15% and 35% respectively. The conductivity increases by 100% and 20% in the through-plane and in-plane direction respectively. Compared with the empirical model, the pore-scale models are in better agreement with the experiments. The validated methods can support microstructure optimization and transport properties improvement for different types of porous electrodes.

Simultaneous 3D measurement for infrared chips with speckle interferometry

Temperature-induced deformation in the infrared detector chip is a key index for evaluating image aberration and stress concentration. Development of an evaluation means for simultaneous characterization of 3D deformation is of great interest to engineering societies. In this study, an integrated device based on speckle interferometry has been developed for evaluation of the three-dimensional (3D) deformation of the infrared detector chip with variations of temperature. With the use of a 3CCD color camera and a group of optical fibers, the 3D displacement components of the detector surface are measured simultaneously during the cooling process. A temporal phase shifting scheme based on GPU parallel computing has been proposed to enable quantitatively real-time 3D measurement in three image layers at a rate of 20 fps. The integrated device has been validated with a benchmark test. The experimental results show a good agreement with the theoretical solution validating the stability and accuracy of the experimental device. The developed speckle interferometry device provides an accurate means in simultaneously evaluating the 3D deformation of the infrared detector chip due to temperature variations.

Correlation-Based Template Tracking Of Moving Object

This paper presents the correlation-based motion estimation technique for the 3D displacement of objects. Two high-speed cameras are configured as a stereovision system and synchronized in real-time. Finger and hand motions are captured in form of digital images at 1500 fps and 2000 fps respectively. A complete motion acquisition system is calibrated to determine the intrinsic and extrinsic parameters which were later used in the correlation algorithm. The grayscale image frames acquired from the cameras are correlated using square templates of 10x10 pixels created from the reference image. The finger and hand motion are discussed with varying camera speed as a measure of brightness inconsistency. The observations in the correlation coefficient indicate that the proposed algorithm is efficient up to 20 and 50 templates for the finger and hand motion cases respectively. The correlation coefficient for finger motion was increased to 0.987 and 0.972 for the left and right cameras, respectively, while the correlation coefficient for hand motion was 0.924 and 0.898. The proposed algorithm is developed in MATLAB and validated by tracing the sinusoidal motion of a solid rectangular element from the image correlation technique and an accelerometer sensor mounted over the block.

InSAR Study of Landslides: Early Detection, Three-Dimensional, and Long-Term Surface Displacement Estimation—A Case of Xiaojiang River Basin, China

Landslides, a major natural geohazard, obstruct municipal constructions and may destroy villages and towns, at worst causing significant casualties and economic losses. Interferometric Synthetic Aperture Radar (InSAR) technique offers distinct advantages on landslide detection and monitoring. In this paper, a more systematic workflow is designed for InSAR study of landslides, in terms of three levels: (i) early detection on regional scale, (ii) three-dimensional (3D) surface displacement rates estimation on detailed scale, and (iii) time series analysis on long-term temporal scale. The proposed workflow is applied for landslide research on the Xiaojiang River Basin, China, using ascending and descending Sentinel-1 images acquired from March 2017 to May 2019. First, the landslide inventory has been mapped and updated using InSAR stacking method, supporting geohazard prevention on a regional scale. A total of 22 active landslides are identified, ranging from medium to super large scale. Compared with the existing inventory, three unrecorded landslides are newly detected by our approach, and five recorded landslides are detected significant expansion of their boundaries. Then, specific to a detected landslide, Baobao landslide, a Total Least Squares–Kalman Filter-based approach is presented. Two outcomes are provided for further spatial-temporal pattern analysis: 3D displacement rates, providing an intuitive insight on the spatial characteristics and sliding direction of landslide, which are analyzed to deep the understanding of its kinematic mechanism, and long-term time series, which contribute to deduce the dynamic evolution of landslide, presenting benefits in landslide forecasting.

Exploiting phase-based motion magnification for the measurement of subtle 3D deformation maps with FP + 2D-DIC

Phase-Based Motion Magnification (PBMM) is an effective methodology to visualise imperceptible phenomena based on magnifying periodic subtle movements on image sequences. Moreover, the integration of the optical techniques Fringe Projection and 2D Digital Image Correlation (FP + 2D-DIC) make it possible to obtain 3D displacement maps employing a single camera.In this study, the integration of PBMM with FP + 2D-DIC is exploited for the determination of subtle 3D displacements. An initial solid-rigid test validates of the combination of those techniques. A later test, employing a cantilever beam, demonstrates its correct performing in the determining of Operational Deflection Shapes. In both cases, the results are compared with those obtained with 3D-DIC and Scanning Laser Doppler Vibrometer (SLDV) to evaluate the relation between the magnification factor and the result obtained. Finally, the potential of the proposed integration for the determination of complex mode shapes is demonstrated by obtaining the ODSs of an industrial component.

Comparative study on the influence of anterior and posterior scars of hard palate on maxillary growth after cleft palate surgery: a three-dimensional finite element analysis.

This study aimed to compare the inhibition of anterior and posterior scars of the hard palate on maxillary growth after cleft palate surgery. Ansys was used to establish two 3D finite element models of maxilla with complete and incomplete cleft palate. The palatal scar force with same magnitude and direction but different areas was applied in four groups in the two models. The loading force was applied to 1/4 of the anterior oral surface of the hard palate (group 1), 1/4 of the middle and anterior oral surface of the hard palate (group 2), 1/4 of the middle and posterior oral surface of the hard palate (group 3), and 1/4 of the posterior oral surface of the hard palate (group 4). The displacement of each group after loading was analyzed and compared. In the two models, maxillary deformation occurred in all groups. The total displacement and 3D displacement comparison of each group was arranged as follows: group 1>group 2>group 3>group 4. Scars from different parts of the hard palate after cleft palate surgery can inhibit maxillary growth in a 3D direction. The anterior scars have more serious inhibition than the posterior scars.

Lake ice deformation on Khovsgol Lake from Sentinel data before, during and after the 2021 Mw 6.7 earthquake in Turt, Mongolia

AbstractKhovsgol Lake, a seasonal ice-covered lake located in boreal Siberia, plays important economic, transportation and agricultural roles for local residents. On 11 January 2021, an Mw 6.7 earthquake struck the center of this lake, providing a unique opportunity to better understand lake ice movement, ridge distribution, and hydraulic and hydrodynamic processes, as a result of the mainshock. We use a pixel-tracking method on both Sentinel-1 synthetic aperture radar and Sentinel-2 optical remote-sensing data covering this lake before, during and after the mainshock to obtain lake-ice displacement. Combining these measurements with different viewing geometries, we determine the locations of pressure ridges in each period and derive their relative 3D displacement maps with a precision of <2.2 m. Our results indicate a large E-W displacement of up to 10.3 m and a vertical displacement of up to 4.6 m during the coseismic period, which has a distinctly different magnitude and pattern of displacement compared to the pre- and post-event periods. Given the ice motion pattern and magnitude, we speculate that the unique ice displacement of Khovsgol Lake may have been caused by a rare seismic seiche after the mainshock.

Effect of the number of projections in X-ray CT imaging on image quality and digital volume correlation measurement

Digital volume correlation (DVC) quantifies internal 3D displacement and strain fields by correlating the volume images of a tested object acquired at different states. When using X-ray CT-based DVC, the number of projections is a key parameter that affects the acquisition time and quality of reconstructed volumetric images, and therefore the precision and temporal resolutions of DVC measurement. More projections result in high-quality volume images for DVC calculation but longer acquisition time and pronounced thermal drifts of the X-ray source. Few projections lead to quicker acquisition and fewer thermal drifts, but may degrade image quality and thus induce larger DVC measurement errors. Selecting an appropriate number of projections during CT imaging is therefore of practical significance for DVC measurement. To solve this dilemma, the effect of the number of projections on DVC measurements with X-ray CT is experimentally investigated in this work. First, numerically simulated speckle volume images with different numbers of projections were reconstructed by using FDK (Feldkamp) algorithm, and the influence of the number of projections on DVC measurement was analyzed. Then, real rescan and compression experiments performed on a copper foam sample were carried out to further study the effect of projection number on DVC measurements. Both simulation and real experiments show that more projections result in longer imaging time but higher quality volume image and DVC measurement. DVC measurement errors decrease with the increase of projections at different decline rates. Therefore, an appropriate number of projections can be specified based on the results according to the requirements of DVC measurement precision and temporal resolution. For the specific X-ray CT device used in this real compression experiment, 36 ∼ 60 projections are suggested to balance measurement precision and temporal resolution, and more than 720 projections are necessary for pursuing higher accuracy.

Crack propagation in fine grained graphites under mode I and mixed-mode loading, as observed in situ by microtomography

Stable crack growth under mode I and mixed-mode loading of two fine grained advanced graphites, SNG742 and T220, has been studied within small (18 mm diameter) specimens of the diametral compression disc geometry to investigate the criterion for crack propagation. Cracks were propagated from a central notch, inclined at 0° or 30° to the loading axis, as the tests were observed in situ by X-ray computed microtomography. The three-dimensional (3D) displacement fields were measured by digital volume correlation. The crack shape, tip location and crack opening displacements were determined by 3D phase congruency edge detection of full field displacements. Linear elastic 3D finite element simulations calculated the J-integral and mode I, mode II and mode III stress intensity factors (SIFs) acting on the crack tip, using the full field displacements as boundary conditions. For SNG742 and T220 specimens with notch angle of 0°, nearly pure mode I crack propagation was obtained. For specimens loaded with the 30° notch angle, the SIFs changed from mixed mode I/II towards pure mode I as the crack propagated. The mode II SIF was less than 20% of the mode I SIF, and as the crack extended over a distance ∼3 mm, the critical mode I SIF (fracture toughness) was insensitive to the mode II SIF, with SNG742 graphite having higher fracture toughness than T220 graphite.

Three-Dimensional Surface Displacements of the 8 January 2022 Mw6.7 Menyuan Earthquake, China from Sentinel-1 and ALOS-2 SAR Observations

The 8 January 2022 Mw6.7 Menyuan earthquake was generated in the transition zone between the western Lenglongling fault and the eastern Tuolaishan fault, both being part of the Qilian–Haiyuan fault system with an important role in the adjustment of the regional tectonic regime. In this study, four pairs of SAR (synthetic aperture radar) data from Sentinel-1 and ALOS-2 (Advanced Land Observation Satellite-2) satellites were used to derive the surface displacement observations along the satellite line-of-sight (LOS) and azimuth directions using the differential interferometric SAR (InSAR, DInSAR), pixel offset-tracking (POT), multiple aperture InSAR (MAI), and burst overlap InSAR (BOI) methods. An SM-VCE method (i.e., a method for measuring three-dimensional (3D) surface displacements with InSAR based on a strain model and variance component estimation) was employed to combine these derived SAR displacement observations to calculate the 3D co-seismic displacements. Results indicate that the 2022 Menyuan earthquake was dominated by left-lateral slip, and the maximum horizontal and vertical displacements were 1.9 m and 0.6 m, respectively. The relative horizontal surface displacement across the fault was as large as 2–3 m, and the fault-parallel displacement magnitude was larger on the southern side of the fault compared with the northern side. Furthermore, three co-seismic strain invariants were also investigated, revealing that the near-fault area suffered severe deformation, and two obviously expanding and compressed zones were identified. We provide displacements/strains derived in this study in the prevailing geotiff format, which will be useful for the broad community studying this earthquake; in addition, the SM-VCE code used in this study is open to the public so that readers can better understand the method.

Combined evaluation of Young modulus and fracture toughness in small specimens of fine grained nuclear graphite using 3D image analysis

The fracture toughness of the fine-grained nuclear graphite SNG742 has been investigated by observation of stable crack propagation in double cleavage drilled compression specimens. The three-dimensional displacement fields were obtained by digital volume correlation (DVC) of in situ laboratory X-ray computed tomographs. The crack tip location and crack opening displacements were determined using an image edge detection algorithm based on the wavelet modulus maxima. The Young modulus was estimated by fitting a finite element model to DVC displacement field data measured before crack initiation. Using the 3D crack geometry and the surrounding full-field 3D displacement fields as boundary conditions, the elastic strain energy release rate J and the three-dimensional stress intensity factors KI to KIII were then evaluated via the contour integral method. Constant mode I critical stress intensity factor was obtained along the curved crack fronts, with negligible shearing modes. This method allows evaluation of the fracture toughness without prior knowledge of elastic properties, and has potential applications to assess the effects of high temperature, oxidation and irradiation in small specimens of nuclear graphite.

Minimum non-isotropic and asymmetric margins for taking into account intrafraction prostate motion during moderately hypofractionated radiotherapy

PurposeTo investigate the impact on dose distribution of intrafraction motion during moderate hypofractionated prostate cancer treatments and to estimate minimum non-isotropic and asymmetric (NI-AS) treatment margins taking motion into account. MethodsProstate intrafraction 3D displacements were recorded with a transperineal ultrasound probe and were evaluated in 46 prostate cancer patients (876 fractions) treated by moderate hypofractionated radiation therapy (60 Gy in 20 fractions). For 18 patients (346 fractions), treatment plans were recomputed increasing CTV-to-PTV margins from 0 to 6 mm with an auto-planning optimization algorithm. Dose distribution was estimated using the voxel shifting method by displacing CTV structure according to the retrieved movements. Time-dependent margins were finally calculated using both van Herk’s formula and the voxel shifting method. ResultsMean intrafraction prostate displacements observed were −0.02 ± 0.52 mm, 0.27 ± 0.78 mm and −0.43 ± 1.06 mm in left–right, supero-inferior and antero-posterior directions, respectively. The CTV dosimetric coverage increased with increased CTV-to-PTV margins but it decreased with time. Hence using van Herk’s formula, after 7 min of treatment, a margin of 0.4 and 0.5 mm was needed in left and right, 1.5 and 0.7 mm in inferior and superior and 1.1 and 3.2 mm in anterior and posterior directions, respectively. Conversely, using the voxel shifting method, a margin of 0 mm was needed in left–right, 2 mm in superior, 3 mm in inferior and anterior and 5 mm in posterior directions, respectively. With this latter NI-AS margin strategy, the dosimetric target coverage was equivalent to the one obtained with a 5 mm homogeneous margin. ConclusionsNI-AS margins would be required to optimally take into account intrafraction motion.

Monitoring of Tunnel Rock Mass Deformations During Provisional Support Stage: A Case Study

Abstract The present study evaluates on site the effects of provisional support on the rate of deformation (convergence) of clay-stone of a twin-tube tunnel. The combination of shotcrete, steel lattice, steel retaining, pre-supporting iron bar and Rock bolts can act as structural support in the form of provisional support for new or existing tunnels. Applications of provisional supports as confinement mechanisms to decrease the capacity of convergence can be helpful for distressed rock mass during tunnels digging. Real-size and real-time field monitoring over a period of approximately one (01) year was carried out with a Tachometer “Leica, TS 09” and 3D Displacement Monitoring Objectives fixed on the top heading and on the invert/bench. Wherefore; a sketch of the same cross-section of the tunnel was used in order to define the deformations of the rock mass of the tunnel measured in 3D in successive periods in all directions along the weak rock mass of the fourth class (IV) after the installation of the provisional support. The study shows good results in terms of deformation of the rock mass of the tunnel and satisfactory stability in terms of confinement. Consequently; it was noticed, that there is a relation between the deformations (convergence) in the two tubes along tunnel - when the deformation of the left tube increases the deformation of the right tube decreases -, and that the deformation of the tunnel is a deformation overall of the rock mass and it is the same along the tunnel relative to its rock mass. It can be concluded that there is a reciprocal effect between the two tunnel tubes, which can be considered as a conservation principle of the rock mass.

Kinematic evaluation and reliability assessment of the Nine Hole Peg Test for manual dexterity

BackgroundThe Nine Hole Peg Test (NHPT) is one of the most frequently used tools to assess manual dexterity. However, no kinematic parameters are provided to describe the quality of the motor performance, since time is the only score. PurposeTo investigate test-retest and intra-rater reliability, correlation with clinical test score, and discriminant validity of kinematic indexes during NHPT. Study DesignA clinical measurement study. MethodsTwenty-five healthy right-handed volunteers performed the NHPT. An experienced physiotherapist administered two sessions at a 6-hour interval with two trials for dominant and non-dominant upper limbs. An optoelectronic system was used to detect NHPT performance, which was divided into nine consecutive peg-grasp, peg-transfer, peg-in-hole, hand-return phases, and one final removing phase. Outcome measures were total and single phases times, normalized jerk, mean, peak and time-to-peak of velocity, curvature index during peg-grasp and hand-return phases, and trunk 3D displacement. The statistical analysis included Intraclass Correlation Coefficients (ICCs) for test-retest and intra-rater reliability, Pearson's coefficients for correlation with the NHPT score, and paired t-tests for discriminant validity. ResultsTest-retest reliability was excellent for trunk rotation (ICC: 0.91) and good to moderate for the other indexes (ICCs: 0.89-0.61). Intra-rater reliability was excellent for total and removing times (ICCs: 0.91 and 0.94) and good to moderate for the other indexes (ICCs: 0.84-0.66), except for trunk inclination (ICC: 0.37). NHPT phases, normalized jerk, mean velocity, peak of velocity, time-to-peak and curvature index correlated with total time (r-score: 0.8-0.3). NHPT phases and most kinematic indexes discriminated the dominant from non-dominant upper limb, with the greatest effect size for normalized jerk during hand-return (d = 1.16). ConclusionsKinematic indexes during NHPT can be considered for manual dexterity assessment. These indexes may allow for the detection of kinematic changes responsible for NHPT score variations in healthy subjects or patients with upper limb impairments.

A new technique using background oriented schlieren for temperature reconstruction of an axisymmetric open reactive flow

A new technique, called 3D ray tracing, for refractive index field reconstruction of axisymmetric flows from displacement fields measured from background oriented schlieren (BOS) experiments is developed and applied to a lean premixed methane/air reactive flow at Reynolds number of 4000 on a 12 mm diameter circular burner. The temperature distribution is then calculated using a species independent direct relationship between refractive index, temperature, and ambient conditions. The error introduced by the approximation to reach this relationship is quantified using simulated flow fields and is found to be 8% within the inner unburnt region of the flow field, decreasing to 2% through the reaction zone, and then quickly reducing to 0% outside the flow field. The effect of random noise and reconstruction resolution on the accuracy of the method is assessed via application to synthetically generated data sets that mimic the characteristics of a heated air jet expelled into ambient. The novel 3D ray tracing allows for accurate temperature reconstructions of open axisymmetric reactive flows where 2D displacement fields are measured, which is shown to be a shortcoming of current direct methods in literature. Additionally, this is done without the need for any prior knowledge of flow field parameters; only ambient conditions to the system must be known. The simple experimental setup and low computational cost make this approach with BOS a good option for application into existing experimental combustion systems with minimal effort.