scholarly journals Particle reconstruction of volumetric particle image velocimetry with the strategy of machine learning

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Qi Gao ◽  
Shaowu Pan ◽  
Hongping Wang ◽  
Runjie Wei ◽  
Jinjun Wang
Keyword(s):  
Three Dimensional ◽  
Approximate Solutions ◽  
Optimization Methods ◽  
Initial Guess ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Image Velocimetry ◽  
Order Of Magnitude ◽  
Robustness To Noise ◽  
Particle Reconstruction

AbstractThree-dimensional particle reconstruction with limited two-dimensional projections is an under-determined inverse problem that the exact solution is often difficult to be obtained. In general, approximate solutions can be obtained by iterative optimization methods. In the current work, a practical particle reconstruction method based on a convolutional neural network (CNN) with geometry-informed features is proposed. The proposed technique can refine the particle reconstruction from a very coarse initial guess of particle distribution that is generated by any traditional algebraic reconstruction technique (ART) based methods. Compared with available ART-based algorithms, the novel technique makes significant improvements in terms of reconstruction quality, robustness to noise, and at least an order of magnitude faster in the offline stage.

scholarly journals Experimental analysis of the shear flow effect on tidal turbine blade root force from three-dimensional mean flow reconstruction

2020 ◽  
Vol 378 (2178) ◽  
pp. 20200001 ◽  
Author(s):  
B. Gaurier ◽  
Ph. Druault ◽  
M. Ikhennicheu ◽  
G. Germain
Keyword(s):  
Turbine Blade ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Tidal Energy ◽  
Velocity Shear ◽  
Reconstruction Method ◽  
Mean Flow ◽  
Blade Root ◽  
Image Velocimetry ◽  
Tidal Turbine

In the main tidal energy sites like Alderney Race, turbulence intensity is high and velocity fluctuations may have a significant impact on marine turbines. To understand such phenomena better, a three-bladed turbine model is positioned in the wake of a generic wall-mounted obstacle, representative of in situ bathymetric variation. From two-dimensional Particle Image Velocimetry planes, the time-averaged velocity in the wake of the obstacle is reconstructed in the three-dimensional space. The reconstruction method is based on Proper Orthogonal Decomposition and enables access to a representation of the mean flow field and the associated shear. Then, the effect of the velocity gradient is observed on the turbine blade root force, for four turbine locations in the wake of the obstacle. The blade root force average decreases whereas its standard deviation increases when the distance to the obstacle increases. The angular distribution of this phase-averaged force is shown to be non-homogeneous, with variation of about 20% of its time-average during a turbine rotation cycle. Such force variations due to velocity shear will have significant consequences in terms of blade fatigue. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

scholarly journals Novel nonlinear reconstruction method with grey-level quantisation units for electron tomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Norio Baba ◽  
Kenji Kaneko ◽  
Misuzu Baba
Keyword(s):  
Cross Section ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Back Projection ◽  
Grey Level ◽  
Discrete Processing ◽  
Structural Image ◽  
Tomography Reconstruction

AbstractWe report a new computed tomography reconstruction method, named quantisation units reconstruction technique (QURT), applicable to electron and other fields of tomography. Conventional electron tomography methods such as filtered back projection, weighted back projection, simultaneous iterative reconstructed technique, etc. suffer from the ‘missing wedge’ problem due to the limited tilt-angle range. QURT demonstrates improvements to solve this problem by recovering a structural image blurred due to the missing wedge and substantially reconstructs the structure even if the number of projection images is small. QURT reconstructs a cross-section image by arranging grey-level quantisation units (QU pieces) in three-dimensional image space via unique discrete processing. Its viability is confirmed by model simulations and experimental results. An important difference from recently developed methods such as discrete algebraic reconstruction technique (DART), total variation regularisation—DART, and compressed sensing is that prior knowledge of the conditions regarding the specimen or the expected cross-section image is not necessary.

Generation of grain maps by an algebraic reconstruction technique

2003 ◽  
Vol 36 (4) ◽  
pp. 1062-1068 ◽  
Author(s):  
H. F. Poulsen ◽  
Xiaowei Fu
Keyword(s):  
Grain Boundaries ◽  
Three Dimensional ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Layer By Layer ◽  
X Rays ◽  
Algebraic Reconstruction Technique ◽  
Mosaic Spread ◽  
Average Size ◽  
Non Destructive

A reconstruction method is presented for the generation of three-dimensional maps of the grain boundaries within powders or polycrystals. The grains are assumed to have a mosaic spread below 1°. They are mapped layer by layer in a non-destructive way by diffraction with hard X-rays. First the diffraction spots are sorted with respect to grain of origin by the indexing programGRAINDEX. Next for each grain the reconstruction is performed byART– an iterative algebraic algorithm. The method is optimized by simulations. It is verified by a 50 keV study on one embedded layer in an aluminium specimen. The layer comprises ∼50 grain sections of an average size of 100 µm. Based on the use of five reflections per grain, a resolution of ∼5 µm is inferred.

Three-dimensional reconstruction of the 40S ribosomal subunit from rabbit reticulocytes

1987 ◽  
Vol 45 ◽  
pp. 936-937
Author(s):  
Neng-Yu Zhang ◽  
Terence Wagenknecht ◽  
Michael Radermacher ◽  
Tom Obrig ◽  
Joachim Frank
Keyword(s):  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Uranyl Acetate ◽  
Reconstruction Method ◽  
Single Exposure ◽  
Electron Dose ◽  
Ribosomal Subunits ◽  
40S Ribosomal Subunit ◽  
Dimensional Reconstruction ◽  
Rabbit Reticulocytes

We have reconstructed the 40S ribosomal subunit at a resolution of 4 nm using the single-exposure pseudo-conical reconstruction method of Radermacher et al.Small (40S) ribosomal subunits were Isolated from rabbit reticulocytes, applied to grids and negatively stained (0.5% uranyl acetate) in a manner that “sandwiches” the specimen between two layers of carbon. Regions of the grid exhibiting uniform and thick staining were identified and photographed twice (magnification 49,000X). The first micrograph was always taken with the specimen tilted by 50° and the second was of the Identical area untilted (Fig. 1). For each of the micrographs the specimen was subjected to an electron dose of 2000-3000 el/nm2.Three hundred thirty particles appearing in the L view (defined in [4]) were selected from both tilted- and untilted-specimen micrographs. The untilted particles were aligned and their rotational alignment produced the azimuthal angles of the tilted particles in the conical tilt series.

Detection, Averaging, and 3D Reconstruction of Biological Specimens on Hypercubes (Transputer-based) Computers

1990 ◽  
Vol 48 (1) ◽  
pp. 454-455
Author(s):  
Jose-Maria Carazo ◽  
I. Benavides ◽  
S. Marco ◽  
J.L. Carrascosa ◽  
E.L. Zapata
Keyword(s):  
3D Reconstruction ◽  
3D Structure ◽  
Three Dimensional ◽  
Software Tools ◽  
Mapping Method ◽  
Computer Architectures ◽  
Parallel Computer ◽  
Reconstruction Process ◽  
Computing Power ◽  
Order Of Magnitude

Obtaining the three-dimensional (3D) structure of negatively stained biological specimens at a resolution of, typically, 2 - 4 nm is becoming a relatively common practice in an increasing number of laboratories. A combination of new conceptual approaches, new software tools, and faster computers have made this situation possible. However, all these 3D reconstruction processes are quite computer intensive, and the middle term future is full of suggestions entailing an even greater need of computing power. Up to now all published 3D reconstructions in this field have been performed on conventional (sequential) computers, but it is a fact that new parallel computer architectures represent the potential of order-of-magnitude increases in computing power and should, therefore, be considered for their possible application in the most computing intensive tasks.We have studied both shared-memory-based computer architectures, like the BBN Butterfly, and local-memory-based architectures, mainly hypercubes implemented on transputers, where we have used the algorithmic mapping method proposed by Zapata el at. In this work we have developed the basic software tools needed to obtain a 3D reconstruction from non-crystalline specimens (“single particles”) using the so-called Random Conical Tilt Series Method. We start from a pair of images presenting the same field, first tilted (by ≃55°) and then untilted. It is then assumed that we can supply the system with the image of the particle we are looking for (ideally, a 2D average from a previous study) and with a matrix describing the geometrical relationships between the tilted and untilted fields (this step is now accomplished by interactively marking a few pairs of corresponding features in the two fields). From here on the 3D reconstruction process may be run automatically.

Scanning-tunneling spectroscopy on conjugated polymer films

2003 ◽  
Vol 771 ◽  
Author(s):  
M. Kemerink ◽  
S.F. Alvarado ◽  
P.M. Koenraad ◽  
R.A.J. Janssen ◽  
H.W.M. Salemink ◽  
...  
Keyword(s):  
Polymer Films ◽  
Conjugated Polymer ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Direct Consequence ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Band Alignment ◽  
Scanning Tunneling ◽  
Order Of Magnitude

AbstractScanning-tunneling spectroscopy experiments have been performed on conjugated polymer films and have been compared to a three-dimensional numerical model for charge injection and transport. It is found that field enhancement near the tip apex leads to significant changes in the injected current, which can amount to more than an order of magnitude, and can even change the polarity of the dominant charge carrier. As a direct consequence, the single-particle band gap and band alignment of the organic material can be directly obtained from tip height-voltage (z-V) curves, provided that the tip has a sufficiently sharp apex.

Alternative pulmonary artery reconstruction technique in the arterial switch operation

2021 ◽  
Author(s):  
Hisayuki Hongu ◽  
Masaaki Yamagishi ◽  
Yoshinobu Maeda ◽  
Keiichi Itatani ◽  
Masatoshi Shimada ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Arterial Switch Operation ◽  
Late Complication ◽  
Late Complications ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Arterial Switch ◽  
Switch Operation ◽  
Longitudinal Extension

Abstract OBJECTIVES Late complications of arterial switch operations (ASO) for transposition of the great arteries, such as neo-pulmonary artery (PA) stenosis and/or neoaortic regurgitation, have been reported. We developed an alternative reconstruction method called the longitudinal extension (LE) method to prevent PA bifurcation stenosis (PABS). METHODS We identified 48 patients diagnosed with transposition of the great arteries and performed ASO using the Lecompte manoeuvre for neo-PA reconstruction. In 9 consecutive patients (from 2014), the LE method was performed (LE). Before 2014, conventional techniques were performed in 39 patients (C). The median body weight and age in the LE and C groups were 3.0 and 3.1 kg and 12 and 26 days, respectively. In the LE group, 1 patient underwent bilateral PA banding before ASO. In C, PA banding and arch repair were performed in 1 patient each. Patients who received concomitant procedures were included. RESULTS The median follow-up in LE and C groups was 1.9 and 10.1 years, respectively. Early mortality/late death was not found in group LE and in 1 patient in group C. Only 1 case required ascending aorta sliding plasty in LE, and 8 patients needed PA augmentation for PABS in C. The median velocity of right/left PA was measured as 1.6/1.9 m/s in LE and 2.1/2.3 m/s in C, so it showed a lower value in LE. CONCLUSIONS Excellent mid-term results were obtained with the LE method. It was considered a useful procedure in preventing PABS, which is a primary late complication of ASO. Further follow-up and investigations are needed.

scholarly journals Origin and Application of the Twinned Calcite Strain Gauge

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 296
Author(s):  
Richard H. Groshong
Keyword(s):  
Stress Analysis ◽  
Strain Gauge ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Constant Strain Rate ◽  
Axis Orientation ◽  
Order Of Magnitude ◽  
Rate Experiment ◽  
Strain Axis ◽  
Expected Values

This paper is a personal account of the origin and development of the twinned-calcite strain gauge, its experimental verification, and its relationship to stress analysis. The method allows the calculation of the three-dimensional deviatoric strain tensor based on five or more twin sets. A minimum of about 25 twin sets should provide a reasonably accurate result for the magnitude and orientation of the strain tensor. The opposite-signed strain axis orientation is the most accurately located. Where one strain axis is appreciably different from the other two, that axis is generally within about 10° of the correct value. Experiments confirm a magnitude accuracy of 1% strain over the range of 1–12% axial shortening and that samples with more than 40% negative expected values imply multiple or rotational deformations. If two deformations are at a high angle to one another, the strain calculated from the positive and negative expected values separately provides a good estimate of both deformations. Most stress analysis techniques do not provide useful magnitudes, although most provide a good estimate of the principal strain axis directions. Stress analysis based on the number of twin sets per grain provides a better than order-of-magnitude approximation to the differential stress magnitude in a constant strain rate experiment.

scholarly journals Automatic Reconstruction of Multi-Level Indoor Spaces from Point Cloud and Trajectory

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3493
Author(s):  
Gahyeon Lim ◽  
Nakju Doh
Keyword(s):  
Point Cloud ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Reconstruction Method ◽  
Complex Environments ◽  
Indoor Space ◽  
Multi Level ◽  
Level Building ◽  
Indoor Spaces ◽  
Data Term

Remarkable progress in the development of modeling methods for indoor spaces has been made in recent years with a focus on the reconstruction of complex environments, such as multi-room and multi-level buildings. Existing methods represent indoor structure models as a combination of several sub-spaces, which are constructed by room segmentation or horizontal slicing approach that divide the multi-room or multi-level building environments into several segments. In this study, we propose an automatic reconstruction method of multi-level indoor spaces with unique models, including inter-room and inter-floor connections from point cloud and trajectory. We construct structural points from registered point cloud and extract piece-wise planar segments from the structural points. Then, a three-dimensional space decomposition is conducted and water-tight meshes are generated with energy minimization using graph cut algorithm. The data term of the energy function is expressed as a difference in visibility between each decomposed space and trajectory. The proposed method allows modeling of indoor spaces in complex environments, such as multi-room, room-less, and multi-level buildings. The performance of the proposed approach is evaluated for seven indoor space datasets.

scholarly journals Small footprint optoelectrodes using ring resonators for passive light localization

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Vittorino Lanzio ◽  
Gregory Telian ◽  
Alexander Koshelev ◽  
Paolo Micheletti ◽  
Gianni Presti ◽  
...  
Keyword(s):  
State Of The Art ◽  
Three Dimensional ◽  
Network Activity ◽  
Ring Resonators ◽  
Spatiotemporal Resolution ◽  
Optical Ring Resonators ◽  
Light Localization ◽  
Order Of Magnitude ◽  
Small Footprint

AbstractThe combination of electrophysiology and optogenetics enables the exploration of how the brain operates down to a single neuron and its network activity. Neural probes are in vivo invasive devices that integrate sensors and stimulation sites to record and manipulate neuronal activity with high spatiotemporal resolution. State-of-the-art probes are limited by tradeoffs involving their lateral dimension, number of sensors, and ability to access independent stimulation sites. Here, we realize a highly scalable probe that features three-dimensional integration of small-footprint arrays of sensors and nanophotonic circuits to scale the density of sensors per cross-section by one order of magnitude with respect to state-of-the-art devices. For the first time, we overcome the spatial limit of the nanophotonic circuit by coupling only one waveguide to numerous optical ring resonators as passive nanophotonic switches. With this strategy, we achieve accurate on-demand light localization while avoiding spatially demanding bundles of waveguides and demonstrate the feasibility with a proof-of-concept device and its scalability towards high-resolution and low-damage neural optoelectrodes.

Sign in / Sign up

Export Citation Format

Share Document