Techniques for high-speed digital imaging of gas concentrations in turbulent flows

1987 ◽  
Vol 5 (3) ◽  
pp. 177-183 ◽  
Author(s):  
M. Winter ◽  
J. K. Lam ◽  
M. B. Long
Keyword(s):  
Turbulent Flows ◽  
Digital Imaging ◽  
High Speed

The bright future of digital imaging in scanning electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 768-769
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Digital Imaging ◽  
High Speed ◽  
High Performance ◽  
Mass Storage ◽  
Analog To Digital ◽  
Central Processing ◽  
Digital Imaging Technology ◽  
Scanning Electron

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 × 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 × 4096 resolution or greater. The two major categories of SEM systems to which digital technology have been applied are:In the analog SEM system the scan generator is normally operated in an analog manner and the image is displayed in an analog or "slow scan" mode.

scholarly journals Optimal nonlinear eddy viscosity in Galerkin models of turbulent flows

2015 ◽  
Vol 766 ◽  
pp. 337-367 ◽  
Author(s):  
Bartosz Protas ◽  
Bernd R. Noack ◽  
Jan Östh
Keyword(s):  
Turbulent Flows ◽  
High Speed ◽  
Eddy Viscosity ◽  
Broad Class ◽  
Constitutive Relations ◽  
Body Height ◽  
Mixing Layer ◽  
The Body ◽  
Stream Velocity ◽  
Initial Vorticity

AbstractWe propose a variational approach to the identification of an optimal nonlinear eddy viscosity as a subscale turbulence representation for proper orthogonal decomposition (POD) models. The ansatz for the eddy viscosity is given in terms of an arbitrary function of the resolved fluctuation energy. This function is found as a minimizer of a cost functional measuring the difference between the target data coming from a resolved direct or large-eddy simulation of the flow and its reconstruction based on the POD model. The optimization is performed with a data-assimilation approach generalizing the 4D-VAR method. POD models with optimal eddy viscosities are presented for a 2D incompressible mixing layer at $\mathit{Re}=500$ (based on the initial vorticity thickness and the velocity of the high-speed stream) and a 3D Ahmed body wake at $\mathit{Re}=300\,000$ (based on the body height and the free-stream velocity). The variational optimization formulation elucidates a number of interesting physical insights concerning the eddy-viscosity ansatz used. The 20-dimensional model of the mixing-layer reveals a negative eddy-viscosity regime at low fluctuation levels which improves the transient times towards the attractor. The 100-dimensional wake model yields more accurate energy distributions as compared to the nonlinear modal eddy-viscosity benchmark proposed recently by Östh et al. (J. Fluid Mech., vol. 747, 2014, pp. 518–544). Our methodology can be applied to construct quite arbitrary closure relations and, more generally, constitutive relations optimizing statistical properties of a broad class of reduced-order models.

Vocal Fold Vibratory Characteristics in Normal Female Speakers From High-Speed Digital Imaging

2012 ◽  
Vol 26 (2) ◽  
pp. 239-253 ◽  
Author(s):  
Kartini Ahmad ◽  
Yuling Yan ◽  
Diane M. Bless
Keyword(s):  
Digital Imaging ◽  
Vocal Fold ◽  
High Speed ◽  
Normal Female

scholarly journals Relation between Voice Quality and Pathological Vibratory Patterns Using High-Speed Digital Imaging.

1999 ◽  
Vol 102 (3) ◽  
pp. 354-367 ◽  
Author(s):  
Mamiko Miyaji ◽  
Yoshitake Iwamoto ◽  
Makoto Oda ◽  
Seiji Niimi
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Voice Quality

Estimation of glottal area function using stereo-endoscopic high-speed digital imaging

2010 ◽  
Author(s):  
Hiroshi Imagawa ◽  
Ken-Ichi Sakakibara ◽  
Isao T. Tokuda ◽  
Mamiko Otsuka ◽  
Niro Tayama
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Area Function

High-speed digital imaging of the neoglottis after supracricoid laryngectomy with cricohyoidoepiglottopexy

2010 ◽  
Vol 142 (4) ◽  
pp. 598-604 ◽  
Author(s):  
Koichiro Saito ◽  
Miwako Kimura ◽  
Hiroshi Imagawa ◽  
Takaharu Nito ◽  
Niro Tayama ◽  
...  
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Supracricoid Laryngectomy
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