Experimental investigations on diffusion characteristics of high concentration jets in environmental currents

2002 ◽  
Vol 23 (12) ◽  
pp. 1429-1436 ◽  
Author(s):  
Zhang Yan ◽  
Wang Dao-zeng ◽  
Fan Jing-yu
Keyword(s):  
Experimental Investigations ◽  
High Concentration ◽  
Diffusion Characteristics

Numerical and Experimental Investigations of the Siemens SGT-800 Burner Fitted to a Water Rig

2017 ◽  
Author(s):  
Daniel Moëll ◽  
Daniel Lörstad ◽  
Annika Lindholm ◽  
David Christensen ◽  
Xue-Song Bai
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Concentration Field ◽  
Simulation Method ◽  
Experimental Investigations ◽  
High Concentration ◽  
Air Mixing ◽  
Les Model ◽  
Gas Turbine Burner

DLE (Dry Low Emission) technology is widely used in land based gas turbines due to the increasing demands on low NOx levels. One of the key aspects in DLE combustion is achieving a good fuel and air mixing where the desired flame temperature is achieved without too high levels of combustion instabilities. To experimentally study fuel and air mixing it is convenient to use water along with a tracer instead of air and fuel. In this study fuel and air mixing and flow field inside an industrial gas turbine burner fitted to a water rig has been studied experimentally and numerically. The Reynolds number is approximately 75000 and the amount of fuel tracer is scaled to represent real engine conditions. The fuel concentration in the rig is experimentally visualized using a fluorescing dye in the water passing through the fuel system of the burner and recorded using a laser along with a CCD (Charge Couple Device) camera. The flow and concentration field in the burner is numerically studied using both the scale resolving SAS (Scale Adaptive Simulation) method and the LES (Large Eddy Simulation) method as well as using a traditional two equation URANS (Unsteady Reynolds Average Navier Stokes) approach. The aim of this study is to explore the differences and similarities between the URANS, SAS and LES models when applied to industrial geometries as well as their capabilities to accurately predict relevant features of an industrial burner such as concentration and velocity profiles. Both steady and unsteady RANS along with a standard two equation turbulence model fail to accurately predict the concentration field within the burner, instead they predict a concentration field with too sharp gradients, regions with almost no fuel tracer as well as regions with far too high concentration of the fuel tracer. The SAS and LES approach both predict a more smooth time averaged concentration field with the main difference that the tracer profile predicted by the LES has smoother gradients as compared to the tracer profile predicted by the SAS. The concentration predictions by the SAS model is in reasonable agreement with the measured concentration fields while the agreement for the LES model is excellent. The LES shows stronger fluctuations in velocity over time as compared to both URANS and SAS which is due to the reduced amounts of eddy viscosity in the LES model as compared to both URANS and SAS. This study shows that numerical methods are capable of predicting both velocity and concentration in a gas turbine burner. It is clear that both time and scale resolved methods are required to accurately capture the flow features of this and probably most industrial DLE gas turbine burners.

scholarly journals Experimental Investigations on the Thermal Diffusion Characteristics and Photoluminescence in Multiphase Micro Fluids Containing ZnO Micro Tubes and Fluorescein Dye-=SUP=-*-=/SUP=-

2020 ◽  
Vol 128 (12) ◽  
pp. 1933
Author(s):  
Francis Frincy ◽  
E.I. Anila ◽  
Ani Joseph Santhi
Keyword(s):  
Thermal Diffusion ◽  
Thermal Lens ◽  
Heat Diffusion ◽  
Experimental Investigations ◽  
Dual Beam ◽  
Diffusion Characteristics ◽  
Fluorescence Efficiency ◽  
Lasing Medium ◽  
Growth Method ◽  
Fluorescein Dye

Scattering of light by disordered structures is normally detrimental to their applicability in many optoelectronic devices. However, some micro and nanostructures are useful in enhancing several optical and thermal properties like emission, heat diffusion etc. For this purpose, we have optimized the low temperature hydrothermal growth method for the ZnO micro tubes which leads to the growth of ZnO as mono dispersed micro tubes. Further, these samples were used to enhance the fluorescence efficiency of disordered media consisting of micro tubes of ZnO and fluorescein dye and to optimize the thermal diffusion of the mixture which will help us optimize the composition of these microscopic inclusions in designing a random lasing medium. Dual beam thermal lens method was used for this purpose. Keywords: thermal lens, thermal fluidics, thermal diffusivity, ZnO micro tubes, fluorescein.

Phosphorus Diffusion From Doped Si1−xGex, Films into Silicon

1999 ◽  
Vol 568 ◽  
Author(s):  
S. Kobayashi ◽  
M. Iizuka ◽  
T. Aoki ◽  
N. Mikoshiba ◽  
M. Sakuraba ◽  
...  
Keyword(s):  
Differential Resistance ◽  
High Concentration ◽  
Phosphorus Diffusion ◽  
P Concentration ◽  
Diffusion Characteristics ◽  
P Diffusion ◽  
Concentration Diffusion ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTPhosphorus diffusion from in-situ doped Si1−xGex epitaxial films into Si at 800°C was investigated using secondary ion mass spectroscopy and differential resistance measurements. The surface P concentration in the diffused layer in Si was higher than the P concentration in the Si1−xGex, film in the present conditions, which signifies the segregation of P from the Si1−xGex, film into Si. The segregation coefficient, defined as the ratio of the active P concentration in the Si to that in the Si1−xGex, film, was about 2.5 in the case of the Si0.75Ge0.25 film as a diffusion source and increased with increasing Ge fraction. The P diffusion profiles in Si were normalized by x/√, even though the segregation of P occurred. The high concentration diffusion characteristics of P in Si were similar to those reported by using conventional diffusion sources.

Cytomembrane Preservation in Tissue Dehydrated Only With Glutaraldehyde and Epon 812 Resin

1973 ◽  
Vol 31 ◽  
pp. 320-321
Author(s):  
Daniel C. Pease
Keyword(s):  
Diffraction Pattern ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Unpublished Study ◽  
X Ray ◽  
Sectioned Material

A previous study demonstrated that tissue could be successfully infiltrated with 50% glutaraldehyde, and then subsequently polymerized with urea to create an embedment which retained cytomembrane lipids in sectioned material. As a result, the 180-190 Å periodicity characteristic of fresh, mammalian myelin was preserved in sections, as was a brilliant birefringence, and the capacity to bind OsO4 vapor in the hydrophobic bilayers. An associated (unpublished) study, carried out in co-operation with Drs. C.K. Akers and D.F. Parsons, demonstrated that the high concentration of glutaraldehyde (and urea) did not significantly alter the X-ray diffraction pattern of aldehyde-fixed, myelin. Thus, by itself, 50% glutaraldehyde has little effect upon cytomembrane systems and can be used with confidence for the first stages of dehydration.

Effects of carbamylcholine on chick embryo aggregate retina cell cultures

1988 ◽  
Vol 46 ◽  
pp. 350-351
Author(s):  
Glenn M. Cohen ◽  
Radharaman Ray
Keyword(s):  
Cell Cultures ◽  
Single Cells ◽  
Retinal Cell ◽  
Cell Aggregates ◽  
High Concentration ◽  
In Ovo ◽  
Sterile Culture ◽  
Retinal Tissue ◽  
Synaptic Junctions ◽  
And Control

Retinal,cell aggregates develop in culture in a pattern similar to the in ovo retina, forming neurites first and then synapses. In the present study, we continuously exposed chick retinal cell aggregates to a high concentration (1 mM) of carbamylcholine (carbachol), an acetylcholine (ACh) analog that resists hydrolysis by acetylcholinesterase (AChE). This situation is similar to organophosphorus anticholinesterase poisoning in which the ACh level is elevated at synaptic junctions due to inhibition of AChE, Our objective was to determine whether continuous carbachol exposure either damaged cholino- ceptive neurites, cell bodies, and synaptic elements of the aggregates or influenced (hastened or retarded) their development.The retinal tissue was isolated aseptically from 11 day embryonic White Leghorn chicks and then enzymatically (trypsin) and mechanically (trituration) dissociated into single cells. After washing the cells by repeated suspension and low (about 200 x G) centrifugation twice, aggregate cell cultures (about l0 cells/culture) were initiated in 1.5 ml medium (BME, GIBCO) in 35 mm sterile culture dishes and maintained as experimental (containing 10-3 M carbachol) and control specimens.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Influence of nascent polypeptide positive charges on translation dynamics

2020 ◽  
Vol 477 (15) ◽  
pp. 2921-2934
Author(s):  
Rodrigo D. Requião ◽  
Géssica C. Barros ◽  
Tatiana Domitrovic ◽  
Fernando L. Palhano
Keyword(s):  
Mrna Decay ◽  
Translation Termination ◽  
Published Data ◽  
Translation Efficiency ◽  
Amino Acid Residues ◽  
High Concentration ◽  
Strong Argument ◽  
Translation Arrest ◽  
Exit Tunnel ◽  
Positively Charged

Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.

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