Variation Characteristics of Reactive Plumes in the Process of Extinguishing Diesel Flame by Water Mist

2012 ◽  
Vol 260-261 ◽  
pp. 10-16
Author(s):  
Liang Wang ◽  
Shi Chuan Su
Keyword(s):  
Large Scale ◽  
Volume Fraction ◽  
Early Stage ◽  
Three Dimensional ◽  
Water Mist ◽  
Jet Flame ◽  
Eddy Structure ◽  
Cumulative Volume ◽  
Variation Characteristics ◽  
Important Significance

By using the three-dimensional governing equations of plumes, the cumulative volume fraction and the model of water suppress fire, the variation characteristics of the reactive plumes in the process of water mist suppress the diesel jet flame are studied. For the different effects of water mist and no water mist, the eddy structure of plume, averaged velocity and averaged temperature in the above of fire source are analyzed, respectively. It seems that there are expansibility and geometric symmetry for the eddy structure in the early stage of the water mist control. However, as a whole, the water mist has cooling effect for the plume area, and it can also reduce the spread velocity of plume. The large-scale structure can be formed quickly, and the temperature is affected by the droplet size and droplet density. However, for the case of no water mist, the bursting of smaller scale vortices can be enhanced, and its structural characteristic has an affect on the distribution of averaged temperature. Computational results have important significance for the water mist to be used in the ship engineer room.

Large-scale three-dimensional anisotropic topology optimization of variable-axial lightweight composite structures

2021 ◽  
pp. 1-15
Author(s):  
Yuqing Zhou ◽  
Tsuyoshi Nomura ◽  
Enpei Zhao ◽  
Kazuhiro Saitou
Keyword(s):  
Topology Optimization ◽  
Composite Structures ◽  
Large Scale ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Optimization Method ◽  
Optimized Design ◽  
Adaptive Meshing ◽  
Design Synthesis ◽  
Fiber Placement

Abstract Variable-axial fiber-reinforced composites allow for local customization of fiber orientation and thicknesses. Despite their significant potential for performance improvement over the conventional multiaxial composites and metals, they pose challenges in design optimization due to the vastly increased design freedom in material orientations. This paper presents an anisotropic topology optimization method for designing large-scale, 3D variable-axial lightweight composite structures subject to multiple load cases. The computational challenges associated with large-scale 3D anisotropic topology optimization with extremely low volume fraction are addressed by a tensor-based representation of 3D orientation that would avoid the 2π periodicity of angular representations such as Euler angles, and an adaptive meshing scheme, which, in conjunction with PDE regularization of the density variables, refines the mesh where structural members appear and coarsens where there is void. The proposed method is applied to designing a heavy-duty drone frame subject to complex multi-loading conditions. Finally, the manufacturability gaps between the optimized design and the fabrication-ready design for Tailored Fiber Placement (TFP) is discussed, which motivates future work toward a fully-automated design synthesis.

Large-Scale Three-Dimensional Anisotropic Topology Optimization of Variable-Axial Composite Structures

2020 ◽  
Author(s):  
Yuqing Zhou ◽  
Tsuyoshi Nomura ◽  
Enpei Zhao ◽  
Wei Zhang ◽  
Kazuhiro Saitou
Keyword(s):  
Topology Optimization ◽  
Composite Structures ◽  
Large Scale ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Optimized Design ◽  
Adaptive Meshing ◽  
Design Synthesis ◽  
Fiber Placement ◽  
Future Work

Abstract Variable-axial fiber-reinforced composites allow for local customization of fiber orientation and thicknesses. Despite their significant potential for performance improvement over the conventional multiaxial composites and metals, they pose challenges in design optimization due to the vastly increased design freedom in material orientations. This paper presents an anisotropic topology optimization (TO) method for designing large-scale, 3D variable-axial composite structures. The computational challenge for large-scale 3D TO with extremely low volume fraction is addressed by a tensor-based representation of 3D orientation that would avoid the 2π periodicity of angular representation such as Eular angles, and an adaptive meshing scheme, which, in conjunction with PDE regularization of the density variables, refines the mesh where structural members appear and coarsens where there is void. The proposed method is applied to designing a heavy-duty drone frame subject to complex multi-loading conditions. Finally, the manufacturability gaps between the optimized design and the fabrication-ready design for Tailored Fiber Placement (TFP) is discussed, which motivates future work toward fully-automated design synthesis.

scholarly journals Numerical investigation of flow and scour around a vertical circular cylinder

2015 ◽  
Vol 373 (2033) ◽  
pp. 20140104 ◽  
Author(s):  
C. Baykal ◽  
B. M. Sumer ◽  
D. R. Fuhrman ◽  
N. G. Jacobsen ◽  
J. Fredsøe
Keyword(s):  
Sediment Transport ◽  
Vortex Shedding ◽  
Large Scale ◽  
Stokes Equations ◽  
Early Stage ◽  
Three Dimensional ◽  
Vertical Cylinder ◽  
Suspended Load ◽  
Frequency Variation ◽  
Suspended Sediment Transport

Flow and scour around a vertical cylinder exposed to current are investigated by using a three-dimensional numerical model based on incompressible Reynolds-averaged Navier–Stokes equations. The model incorporates (i) k - ω turbulence closure, (ii) vortex-shedding processes, (iii) sediment transport (both bed and suspended load), as well as (iv) bed morphology. The influence of vortex shedding and suspended load on the scour are specifically investigated. For the selected geometry and flow conditions, it is found that the equilibrium scour depth is decreased by 50% when the suspended sediment transport is not accounted for. Alternatively, the effects of vortex shedding are found to be limited to the very early stage of the scour process. Flow features such as the horseshoe vortex, as well as lee-wake vortices, including their vertical frequency variation, are discussed. Large-scale counter-rotating streamwise phase-averaged vortices in the lee wake are likewise demonstrated via numerical flow visualization. These features are linked to scour around a vertical pile in a steady current.

scholarly journals PanIN-associated pericyte, glial, and islet remodeling in mice revealed by 3D pancreatic duct lesion histology

2016 ◽  
Vol 311 (3) ◽  
pp. G412-G422 ◽  
Author(s):  
Pei-Yu Lin ◽  
Shih-Jung Peng ◽  
Chia-Ning Shen ◽  
Pankaj J. Pasricha ◽  
Shiue-Cheng Tang
Keyword(s):  
Large Scale ◽  
Tissue Injury ◽  
Early Stage ◽  
Three Dimensional ◽  
Image Data ◽  
Intraepithelial Neoplasia ◽  
Glial Activation ◽  
Mutant Mice ◽  
Cellular Heterogeneity ◽  
Low Grade

Pericytes and glial cells are accessory cells of neurovascular networks, which have been reported to participate in scar formation after tissue injury. However, it remains unclear whether similar reactive cellular responses occur in pancreatic intraepithelial neoplasia (PanIN). In this study we developed three-dimensional (3D) duct lesion histology to investigate PanIN and the associated pericyte, glial, and islet remodeling. Transparent mouse pancreata with a KrasG12D mutation were used to develop 3D duct lesion histology. Deep-tissue, tile-scanning microscopy was performed to generate panoramic views of the diseased pancreas for global examination of early stage and advanced duct lesion formation. Fluorescence signals of ductal and neurovascular networks were simultaneously detected to reveal associated remodeling. Significantly, in KrasG12D-mutant mice, when the low-grade PanINs emerge, duct lesions appear as epithelial buds with perilesional pericyte and glial activation. When PanINs occur in large scale (induced by cerulein injections to the mutant mice), the 3D image data identifies 1) aggregation of PanINs in clusters in space; 2) overexpression of the pericyte marker NG2 in the PanIN microenvironment; and 3) epithelial in-growth to islets, forming the PanIN-islet complexes. Particularly, the PanIN-islet complexes associate with proliferating epithelial and stromal cells and receive substantial neurovascular supplies, making them landmarks in the atrophic lobe. Overall, perilesional pericyte and glial activation and formation of the PanIN-islet complex underline cellular heterogeneity in the duct lesion microenvironment. The results also illustrate the advantage of using 3D histology to reveal previously unknown details of neurovascular and endocrine links to the disease.

scholarly journals Segmentation-Less, Automated, Vascular Vectorization

2021 ◽  
Vol 17 (10) ◽  
pp. e1009451
Author(s):  
Samuel A. Mihelic ◽  
William A. Sikora ◽  
Ahmed M. Hassan ◽  
Michael R. Williamson ◽  
Theresa A. Jones ◽  
...  
Keyword(s):  
Image Segmentation ◽  
Statistical Power ◽  
Large Scale ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Vascular Anatomy ◽  
Input Image ◽  
Segmented Images ◽  
Vessel Networks

Recent advances in two-photon fluorescence microscopy (2PM) have allowed large scale imaging and analysis of blood vessel networks in living mice. However, extracting network graphs and vector representations for the dense capillary bed remains a bottleneck in many applications. Vascular vectorization is algorithmically difficult because blood vessels have many shapes and sizes, the samples are often unevenly illuminated, and large image volumes are required to achieve good statistical power. State-of-the-art, three-dimensional, vascular vectorization approaches often require a segmented (binary) image, relying on manual or supervised-machine annotation. Therefore, voxel-by-voxel image segmentation is biased by the human annotator or trainer. Furthermore, segmented images oftentimes require remedial morphological filtering before skeletonization or vectorization. To address these limitations, we present a vectorization method to extract vascular objects directly from unsegmented images without the need for machine learning or training. The Segmentation-Less, Automated, Vascular Vectorization (SLAVV) source code in MATLAB is openly available on GitHub. This novel method uses simple models of vascular anatomy, efficient linear filtering, and vector extraction algorithms to remove the image segmentation requirement, replacing it with manual or automated vector classification. Semi-automated SLAVV is demonstrated on three in vivo 2PM image volumes of microvascular networks (capillaries, arterioles and venules) in the mouse cortex. Vectorization performance is proven robust to the choice of plasma- or endothelial-labeled contrast, and processing costs are shown to scale with input image volume. Fully-automated SLAVV performance is evaluated on simulated 2PM images of varying quality all based on the large (1.4×0.9×0.6 mm3 and 1.6×108 voxel) input image. Vascular statistics of interest (e.g. volume fraction, surface area density) calculated from automatically vectorized images show greater robustness to image quality than those calculated from intensity-thresholded images.

Nano-Micro Geometric Modeling Using Microscopic Image

2012 ◽  
Vol 523-524 ◽  
pp. 345-349 ◽  
Author(s):  
Shin Usuki ◽  
Kenjiro Takai Miura
Keyword(s):  
Geometric Modeling ◽  
High Speed ◽  
Large Scale ◽  
Early Stage ◽  
Three Dimensional ◽  
Measurement Data ◽  
Stage Of Development ◽  
Three Dimensional Measurement ◽  
Micro Features ◽  
Effective Use

In recent years, there are a lot of active researches on nano-micro manufacturing and metrology, since not only industrial fields but also medical fields require higher accuracy with respect to miniaturizing size of the target. However, we cannot make an effective use of three dimensional measurement data for the nano-micro design and manufacturing due to a wide variety of instruments, resolutions, and noises. In fact, the nano-micro geometric modeling is at an early stage of development in spite of its importance for the next generation. In order to find a solution to this problem, we propose to combine the multi-resolution processing with the microscopic images for high speed and non-destructive geometric modeling as well as for the homogeneous modeling from micro features to macro ones. This research includes measurement data tiling between different instruments, high resolution optical microscopic imaging, focus judgment of three dimensional microscopic data, and large scale point crowd processing. These built models are potentially applied to in-line inspections and numerical simulations. Therefore, the nano-micro geometric modeling contribute to further developments of ultra precise manufacturing and the biotechnology.

Vibrational Analysis of Wavy Carbon Nanotube-Reinforced Composites

2011 ◽  
Author(s):  
Mohamad Shafiee Motahar ◽  
Mohammad Taghi Ahmadian
Keyword(s):  
Carbon Nanotube ◽  
Large Scale ◽  
Natural Frequencies ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Vibrational Analysis ◽  
Effective Modulus ◽  
Dimensional Structure ◽  
Reinforced Composites ◽  
Nano Structure

Characterization and simulation of carbon nanotube-reinforced composites at large scale have been a concern of researchers in the past decade. This is due to the computational complication of considering many embedded carbon nanotubes (CNTs). However a simple meshing of organized CNT distribution in the matrix can ease this obstacle. In this study, a finite element approach is employed to investigate the elastodynamic behavior of a wavy CNT-reinforced composite structure. A three dimensional structure with up to 6400 uniformly distributed wavy CNTs is embedded in a polymer matrix. Each wavy nanotube is represented by a set of beam elements. The effect of nanotube waviness and volume fraction on the effective modulus of nanocomposite is evaluated and verified by previous studies. The results demonstrate that waviness tends to decrease the effective modulus of the structure. Furthermore, the natural frequencies of a nano structure at different boundary conditions are examined. The results reveal that the natural frequencies increase with volume fraction of CNT, while a nominal increase of CNT waviness decreases the natural frequencies sharply.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

Sign in / Sign up

Export Citation Format

Share Document