Abstract
When performing Tomo-PIV experiments, the calculation of accurate camera models is a key point for successful measurements. In severe configurations, where optical interfaces are involved ...and refractive index variations occur along the line of sight, analytical models can fail to accurately represent the projection and back-projection functions. This inability can lead to significant inaccuracies in particle location and volume reconstruction, which has a considerable impact on the calculation of velocity fields. In order to overcome these limitations, an innovative camera model based on the combination of an analytical model, such as a pinhole model or a polynomial model, with discrete corrections is proposed. In this method, the analytical projection and back-projection are adjusted with a discrete correction stored in two adaptive grids that save both memory and computation time. These correction grids require calibration which is performed with triangulation procedures similar to those used in misalignment corrections. The calculation and operation of the model are described in this paper. The performance of the camera model is evaluated on simulated and experimental setups based on a large depth-of-field calibration performed in a glass water tank. The presence of multiple optical interfaces and fluids, resulting in large light deviations, makes it difficult to compute a high accuracy camera model. In this configuration, the proposed technique successfully reduces the triangulation error from 1 pixel to less than 0.01 pixel. The usefulness of the model is demonstrated in a Tomo-PIV experiment where the deflection of light through the water tunnel walls prevents classical analytical functions from accurately modelling the projection and back-projection functions. This corrected model can also solve discontinuity problems in the projection functions and can be used when there are interfaces in the measurement volume. It opens new perspectives in the study of fluid-structure interaction when transparent solids are involved.
•Broad review of studies on impinging jets at low nozzle-to-plate distance.•Review of the evolution of the major heat transfer measurement techniques.•Comparison between experimental measurements and ...numerical simulations.•Address of the major strategies for impingement heat transfer enhancement.•Identification of future challenges for experimental research.
The complex flow structures of submerged jets impinging at relatively short nozzle-to-plate distance motivated a huge number of studies in order to allow for the understanding of their thermo-fluid-dynamic features. Herein, some of the experimental contributions evolved while studying the heat transfer behaviour of these jets (with a specific focusing on the secondary annular peak) are reviewed, along with the development of specific experimental techniques in thermal-fluid sciences over the last 50years. A special attention is devoted to some particular, but very relevant, techniques in the field of modern experimental thermo-fluid-dynamics, namely infrared thermography and particle image velocimetry (PIV) along with the recently developed tomographic PIV. The outcomes of their visualization and flow inspection capabilities are compared with those of recent advanced computational methods. As computational simulations continue to grow in magnitude and complexity, it is essential to make certain their reliability, i.e. to validate their results. The experimental techniques of thermo-fluid-dynamics also have undergone a constant and enormous development, so they will provide further comprehensive benchmarks to computational methods. Future challenges for experimentalists in the thermal-fluid field, including convective heat transfer enhancement, are finally outlined.
The paper focuses on the impact of the Stjepović-Skočibuha family in shaping the settlement of Suđurađ on the island of Šipan near Dubrovnik. It discusses the social, economic, and cultural context ...of Šipan in the 16th century, with special reference to the development of Suđurađ. Biographical data of the progenitors of the Stjepović-Skočibuha family are presented, who are merited with the construction of two representative summerhouse and economy assemblies in the settlement, which over time became the main landmarks of Suđurađ. The starting hypothesis of the research is that the summerhouse assemblies of Tomo and especially Vice Stjepović-Skočibuha significantly influenced the urban structuring of the settlement. The stylistic characteristics and organization of the two building assemblies and the associated lands have been analysed in relation to the settlement, with a detailed transcription of the Austrian cadastre from the first half of the 19th century, including an analysis of land ownership and uses of individual land plots, which confirmed the starting hypothesis. The heirs of the family were still the majority owners of buildings and land plots in Suđurađ at the time.
In this paper, we develop a synthetic aperture radar (SAR) tomography-based persistent scatterer interferometry (Tomo-PSInSAR) method to detect single and double persistent scatterers (PSs) in urban ...built environments. By constructing a two-tier network, we can jointly detect single and double PSs with no need for preliminary removal of the atmospheric phase screen (APS) in the whole area. This technique is more applicable in high-rise built environments (e.g., Hong Kong) with cloudy and rainy weather, where there is much uncertainty when removing the APS. In the first-tier network, we aim to detect the most reliable single PSs (SPSs) by constructing a Delaunay triangulation network. To improve the robustness of estimation, we combine beamforming with an M-estimator for parameter estimation at the arcs and introduce a ridge estimator for network adjustment. In the second-tier network, we detect the remaining SPSs and all of the double PSs (DPSs) by constructing local star networks that use the SPSs detected in the first-tier network as reference points. To simplify the detection of DPSs, we employ a local maximum ratio method for extracting overlaid DPSs. Finally, 56 Hong Kong TerraSAR-X images are used to validate the Tomo-PSInSAR method.
The complex three-dimensional (3D) flows around a short cylinder on the wall, acted by a flow exiting from a fore angled hole (FAH) that penetrates the cylinder from the fore to the top end, were ...experimentally investigated. The 3D instantaneous velocity distributions were measured based on tomographic particle image velocimetry (Tomo-PIV). The 3D flow structures behind the FAH and no-hole cylinders are compared in terms of the measured 3D velocity and vorticity distributions, Q-criterion, and tip vortices. A 3D W-type arch vortex, which shows a larger peak or convexity on the horizontal part center than for the no-hole cylinder, is found around the FAH short cylinder. The exiting flow from the FAH increases the separation zone, and FAH height effectively controls the eddy structures. The instantaneous 3D velocity data obtained from Tomo-PIV are decomposed using 3D wavelet multiresolution analysis and proper orthogonal decomposition. With the FAH cylinder, the large-scale streamwise wake vortices are smaller than with the no-hole cylinder, and this exhibits more evident as increasing the FAH height. The time-mean 3D large-scale arch vortical structures, however, become stronger. Proper orthogonal decomposition indicates that the energetic flow structures of the FAH cylinders are stronger than those of the no-hole cylinder.
•D flow structures around a short cylinder are controlled by the issuing flow.•D velocity fields measured by Tomo-PIV are analyzed using 3D wavelet transform.•Issuing flow increases the rear separation zone and controls the vortical structures.•Large-scale streamwise wake vortices are reduced by the issuing flow.•Energetic flow structures become stronger with the action of the issuing flow.
We report a case of a patient performing a positron emission tomography-computed tomography (PET-CT) scan with 18FF-Choline for biochemical relapse (Prostate specific antigen (PSA) 1.2 ng/ml) of ...prostate cancer. Two large areas of focal uptake with a cold core within the liver were observed. A contrast-enhanced ultrasound scan performed after the PET scan characterized these lesions as cavernous hepatic hemangiomas, and therefore, a biopsy was not performed; 3 years of follow-up and PET and MRI finding stability confirmed the benignity of their nature.
•Three-dimensional flow field of a lobed jet is measured by Tomo-PIV.•Fourier mode decomposition is used to identify the energetic large-scale structures.•Turbulence is intensified in the shear layer ...of the lobed jet.•Double helical mode arises in the shear layer of the lobed jet and interacts with the entire jet column.
This study focuses on the dynamics of the three-dimensional jet flow issued from a lobed nozzle. Flow field measurements were performed using a split-screen dual-camera tomographic particle image velocimetry (tomo-PIV) system. The lobed nozzle was constructed using three-circle configuration at the nozzle exit, where the ratio of the circular centre offset to the circle radius was a/b=0.8. Two high-speed cameras were used with an appropriate combination of prismatic and planar mirrors to split each camera into two views. The Reynolds number was fixed at Re=2400, and the circular jet at the same Reynolds number was also measured for comparison. Fourier mode decomposition was used to identify the large-scale structures superposed in the unsteady flow field. The lobe trough in the jet decreased the jet’s width due to the smooth connection between the pipe section and the lobed exit. Turbulence was intensified in the jet shear layer, and the passing fluid puffs in the circular jet instantaneous flow field were also broken in the lobed jet. The successively passing fluid puffs in the circular jet were observed to be the axisymmetric large-scale structure in Fourier modes dominating at St=0.39. However, breakdown of the axisymmetric structures was induced by the lobed nozzle at St=0.51 and 0.65, and the double helical modes arose at St=0.28 and 0.38 (also 0.4) in the shear layer of the jet potential core and interacted with the entire jet column.
In animal germlines, regulation of cell proliferation and differentiation is particularly important but poorly understood. Here, using a cryo-cut approach, we mapped RNA expression along the ...Caenorhabditis elegans germline and, using mutants, dissected gene regulatory mechanisms that control spatiotemporal expression. We detected, at near single-cell resolution, >10,000 mRNAs, >300 miRNAs, and numerous unannotated miRNAs. Most RNAs were organized in distinct spatial patterns. Germline-specific miRNAs and their targets were co-localized. Moreover, we observed differential 3′ UTR isoform usage for hundreds of mRNAs. In tumorous gld-2 gld-1 mutants, gene expression was strongly perturbed. In particular, differential 3′ UTR usage was significantly impaired. We propose that PIE-1, a transcriptional repressor, functions to maintain spatial gene expression. Our data also suggest that cpsf-4 and fipp-1 control differential 3′ UTR usage for hundreds of genes. Finally, we constructed a “virtual gonad” enabling “virtual in situ hybridizations” and access to all data (https://shiny.mdc-berlin.de/spacegerm/).
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•Architecture of mRNA and miRNA expression at near single-cell resolution in worm gonad•For hundreds of genes, 3′ UTR choice and length are regulated during development•In gld-2 gld-1 mutants, 3′ UTR choices are suppressed•A 3D gonad model (SPACEGERM) for virtual in situs is presented
Diag and Schilling et al. present a near single-cell gonad map of mRNAs and miRNAs and previously unannotated miRNAs and 3′ UTRs. By mutant analysis, regulators and mechanisms explaining highly dynamic spatiotemporal changes of 3′ UTR isoforms were identified. A mathematical, interrogable 3D gonad model allows comprehensive resolution of mRNA and miRNA expression in time (min) and space (∼1–100 cells).
Oral cancer is the sixth most common cancer worldwide, predominantly seen in low and middle-income countries (LMIC). Two thirds of all cases are detected at a late stage when prognosis and treatment ...outcomes are poor. Oral lesions are commonly detected by visual inspection, followed by invasive surgical biopsy and time-consuming histopathological analysis. Optical coherence tomography (OCT), a minimally invasive tomographic imaging technology, can be used to non-invasively identify premalignant or malignant change in the oral mucosa. In this study, a mobile OCT imaging system was designed, constructed, and tested for its performance as a point-of-care oral diagnostic device in an LMIC. 20 patients with suspicious oral lesions and 10 healthy subjects were enrolled in this pilot study. Two-dimensional (2-D) OCT images as well as clinical examination data, risk habit history, and histopathology were collected. OCT images for healthy oral mucosa, dysplasia, and malignancy were evaluated in a blinded fashion by visual scoring and computed image processing techniques. It was found that the OCT image processing algorithm performed at or exceeded the performance of visual observer scoring of OCT images.
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