Thin Filament Pyrometry Temperature Measurements in Microgravity Droplet Combustion

2007 ◽  
Author(s):  
A. Yozgatligil ◽  
S. H. Park ◽  
M. Y. Choi
Keyword(s):  
Thin Filament ◽  
Single Point ◽  
Ccd Camera ◽  
Interference Filter ◽  
Drop Tower ◽  
Droplet Combustion ◽  
Experimental Conditions ◽  
Spatially Resolved ◽  
Sic Fiber ◽  
Ethanol Droplet

Thin filament pyrometry (TFP) temperature measurement technique was implemented for the first time in microgravity ethanol droplet combustion experiments at NASA 2.2s drop tower. This technique was first developed by Vilimpoc and Goss [1] and later used by several researchers in both diffusion and premixed flames [2–4]. The advantages of this technique are related to rapid temporal response and spatially-resolved temperature distribution rather than single point measurements (as in the case with thermocouples). The SiC filament is an ideal material as a temperature probe in a flame due to its low thermal conductivity, high resistance to oxidation and its small size. TFP was implemented in microgravity droplet combustion experiments at NASA 2.2s drop tower. An 8 bit CCD camera was used to record the emission from the SiC fiber that was positioned through the center of the droplet (the fiber is also used to suspend the droplet and keep it in the field view of the camera). The camera is equipped with a lens and a 700 nm interference filter, with a FWHM of 25 nm was placed in front of the camera. Neutral density filters were used in order to obtain unsaturated filament images for the various experimental conditions (oxygen concentration, inert, pressure). A 300 nm plano convex lens was placed in front of the droplet flame in order to improve spatial resolution by magnifying the image. The emission measured by the camera along the location of the filament results from the emission from the filament and the flame in the intervening region between the filament and the camera. Figure 1 displays a schematic from the top of the flame and shows the rays from filament towards the camera and the rays from the medium (gas/soot) in front of the filament towards the camera).

scholarly journals Spatially Resolved Forming Mechanisms Detection in Single Point Incremental Forming Using Synchrotron Based Texture Analysis

2021 ◽  
Author(s):  
Mateus Dobecki ◽  
Alexander Poeche ◽  
Walter Reimers
Keyword(s):  
Texture Analysis ◽  
Incremental Forming ◽  
Single Point ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Forming Mechanism ◽  
Spatially Resolved ◽  
Step Down ◽  
Stress States

AbstractDespite the ongoing success of understanding the deformation states in sheets manufactured by single-point incremental forming (SPIF), the unawareness of the spatially resolved influence of the forming mechanisms on the residual stress states of incrementally formed sheet metal parts impedes their application-optimized use. In this study, a well-founded experimental proof of the occurring forming mechanisms shear, bending and stretching is presented using spatially resolved, high-energy synchrotron x-ray diffraction-based texture analysis in transmission mode. The measuring method allows even near-surface areas to be examined without any impairment of microstructural influences due to tribological reactions. The depth-resolved texture evolution for different sets of forming parameters offers insights into the forming mechanisms acting in SPIF. Therefore, the forming mechanisms are triggered explicitly by adjusting the vertical step-down increment Δz for groove, plate and truncated cone geometries. The texture analysis reveals that the process parameters and the specimen geometries used lead to characteristic changes in the crystallites’ orientation distribution in the formed parts due to plastic deformation. These forming-induced reorientations of the crystallites could be assigned to the forming mechanisms by means of defined reference states. It was found that for groove, plate and truncated cone geometries, a decreasing magnitude of step-down increments leads to a more pronounced shear deformation, which causes an increasing work hardening especially at the tool contact area of the formed parts. Larger step-down increments, on the other hand, induce a greater bending deformation. The plastic deformation by bending leads to a complex stress field that involves alternating residual tensile stresses on the tool and residual compressive stresses on the tool-averted side incrementally formed sheets. The present study demonstrates the potential of high-energy synchrotron x-ray diffraction for the spatially resolved forming mechanism research in SPIF. Controlling the residual stress states by optimizing the process parameters necessitates knowledge of the fundamental forming mechanism action.

INVESTIGATION OF SINGLE-POINT DRESSING OVERLAP RATIO AND DIAMOND-ROLL DRESSING INTERFERENCE ANGLE ON SURFACE ROUGHNESS IN GRINDING

2010 ◽  
Vol 34 (2) ◽  
pp. 295-308 ◽  
Author(s):  
Akram Saad ◽  
Robert Bauer ◽  
Andrew Warkentin
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Empirical Model ◽  
Material Removal ◽  
Removal Rate ◽  
Single Point ◽  
Experimental Conditions ◽  
Workpiece Surface ◽  
Different Depths ◽  
Overlap Ratio

This paper investigates the effect of both single-point and diamond-roll dressing techniques on the workpiece surface roughness in grinding. Two empirical surface roughness models are studied – one that incorporates single-point dressing parameters, and another that incorporates diamond-roll dressing parameters. For the experimental conditions used in this research, the corresponding empirical model coefficients are found to have a linear relationship with the inverse of the overlap ratio for single-point dressing and the interference angle for diamond-roll dressing. The resulting workpiece surface roughness models are then experimentally validated for different depths of cut, workpiece speeds and dressing conditions. In addition, the models are used to derive a relationship between overlap ratio for single-point dressing, and interference angle for diamond-roll dressing such that both dressing techniques produce a similar surface finish for a given material removal rate.

LDA Measurements in Rough Surface ZPG Turbulent Boundary layers

2006 ◽  
Author(s):  
Brian Brzek ◽  
Rau´l Bayoa´n Cal ◽  
Gunnar Johansson ◽  
Luciano Castillo
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Laser Doppler Anemometry ◽  
Single Point ◽  
Roughness Parameter ◽  
Reynolds Stresses ◽  
Experimental Conditions ◽  
Boundary Layer Equations ◽  
Entire Boundary ◽  
Boundary Layer Development

A new set of experiments have been performed in order to study the effects of the upstream conditions and the surface roughness on a zero pressure gradient turbulent boundary layer. In order to properly capture the x-dependence of the single point statistics, consecutive measurements of 11 streamwise locations were performed. These 2-D Laser Doppler Anemometry (LDA) measurements enable us to use the full boundary layer equations in order to calculate the skin friction and determine the boundary layer development which is not possible in the majority of experiments on rough surfaces. It will be shown that for fixed experimental conditions (i.e., fixed upstream wind tunnel speed, trip wire, etc), the velocity deficit profiles collapse for each of the scalings investigated but only the Zagarola/Smits scaling (1998) could collapse all the different experimental conditions into a single curve. In addition, the Reynolds stresses were increasingly affected by the surface roughness as the roughness parameter, k+, increased. Moreover, it was found that the shape of the Reynolds stress profiles was very different throughout the entire boundary layer, particularly the < u2 > component. This is likely the result of the flow becoming more isotropic for increased k+, and will be seen in the anisotropy coefficients. Moreover, increased production of < u2 > and < uv > due to roughness is also seen throughout the entire boundary layer although its overall role in the changing shape of the < u2 > profiles still needs to be determined. The effect of roughness on the boundary layer parameters is also evident and their x-dependence is also shown.

Industrial Applications of Near-Infrared Chemical Imaging Microscopy

2001 ◽  
Vol 7 (S2) ◽  
pp. 162-163
Author(s):  
EN Lewis ◽  
LH Kidder ◽  
KS Haber
Keyword(s):  
Spatial Distribution ◽  
Near Infrared ◽  
Imaging System ◽  
Raw Materials ◽  
Single Point ◽  
Nir Spectroscopy ◽  
Chemical Imaging ◽  
Industrial Applications ◽  
Chemical Information ◽  
Spatially Resolved

Single point near-infrared (NIR) spectroscopy is used extensively for characterizing raw materials and finished products in a wide variety of industries: polymers, paper, film, pharmaceuticals, paintings and coatings, food and beverages, agricultural products. As advanced industrial materials become more complex, their functionality is often determined by the spatial distribution of their discrete sample constituents. However, conventional single point NIR spectroscopy cannot adequately probe the interrelationship between the spatial distribution of sample components with the physical properties of the sample. to fully characterize these samples, it is necessary to probe simultaneously spatial and chemical heterogeneity and correlate these properties with sample characteristics.Recently, we have developed a novel NIR imaging spectrometer that can deliver spatially resolved chemical information very rapidly. in contrast to conventional, single point NIR spectrometers, the imaging system uses an infrared focal-plane array (FPA) to collect up to 76,800 complete spectra, one for each pixel on the array, in approximately one minute.

pH dependence of myosin binding-induced activation of the thin filament in cardiac myocytes and skeletal fibers

1996 ◽  
Vol 270 (3) ◽  
pp. H1008-H1014 ◽  
Author(s):  
J. M. Metzger
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Myocytes ◽  
Thin Filament ◽  
Ph Dependence ◽  
Muscle Fibers ◽  
Isometric Tension ◽  
Experimental Conditions ◽  
Skeletal Muscle Fibers ◽  
Myosin Binding ◽  
Fast Twitch

The pH dependence of myosin binding-induced thin filament activation was determined in permeabilized cardiac myocytes and slow- and fast-twitch single skeletal muscle fibers by experimental lowering of [MgATP] in the Ca(2+)-free solutions bathing the permeabilized preparations. As the pS (where S is [MgATP] and pS is -log[MgATP]) was increased from 3.0 to 8.0, isometric tension increased to a peak value in the pS range of 4.9-5.3. At pH 7.00, the transition from the relaxed to the activated rigor state was steep in cardiac myocytes [Hill value (nH) = 21.2 +/- 3.1 (SE)] and due to the apparent effect of strongly bound cross bridges to cooperatively activate the thin filament in the absence of added Ca2+. At pH 6.20, the steepness of the tension-pS relationship was markedly reduced (nH = 6.1 +/- 1.0) and the midpoint of the relationship (pS50) was shifted to higher pS values in cardiac myocytes. In comparison, reduced pH had no effect on the steepness or position of the tension-pS relationship in single slow- or fast-twitch skeletal muscle fibers. These findings suggest that myosin binding-induced activation of the thin filament is pH dependent in cardiac myocytes but not in skeletal muscle fibers under these experimental conditions in which Ca2+ is absent.

Development and Application of Electroluminescence Imaging for CdS/CdTe Characterization

2003 ◽  
Vol 763 ◽  
Author(s):  
Scott Feldman ◽  
Fred Seymour ◽  
Tim Ohno ◽  
Victor Kaydanov ◽  
Reuben Collins
Keyword(s):  
Short Circuit ◽  
Ccd Camera ◽  
Short Circuit Current ◽  
Processing Parameters ◽  
Carrier Injection ◽  
Spatially Resolved ◽  
Carrier Recombination ◽  
Recombination Lifetimes ◽  
Insight Into ◽  
Injection Rates

AbstractA technique for spatially resolved optical characterization of CdS/CdTe thin film solar cells has been developed using electroluminescence (EL). In EL, excess minority carriers are injected via forward biasing. Light produced in radiative carrier recombination is collected with a CCD camera. Because EL intensity depends upon radiative vs. non-radiative recombination lifetimes, EL provides insight into material quality.Spatial resolution is a key benefit of EL as it provides insight into the non-uniformities of polycrystalline CdTe. At high magnification the resolution is diffraction limited, but coarser measurements of up to several millimeters in range may also be made. Non-uniformities in emission have been observed throughout this range.Further benefits of EL as a characterization technique are as follows: EL probes the region of most interest, namely the CdTe near the main junction. Also, it is observable at room temperature and data acquisition is fast. Finally, EL is observable at very low carrier injection rates, comparable to short circuit current. (Though more structure is often revealed at higher injection rates.) This low injection means that EL can be a non-destructive probe. This fact, along with the aforementioned ease of observation, means that EL could possibly be used for quality control and in situ testing of modules.Data gathered from CdS/CdTe cells from various institutions deposited using different methods such as close spaced sublimation, vapor transport, and sputtering are presented. In addition to changes in deposition technique, changes in processing parameters were observed to affect EL emission. Furthermore, overall EL emission decreased noticeably with stress at various biases and elevated temperature, with non-uniformity increasing in many cases. Changes in EL become apparent before changes in parameters acquired with standard current-voltage measurements, suggesting that this technique can be used as an early indicator for degrading cells. Finally, some dramatic changes in EL with stress suggest highly non-uniform degradation of the back contact.

scholarly journals Numerical Analysis for Predicting the Performance of Wave Observation Buoy: Dynamic Analysis under Regular Wave

2021 ◽  
Vol 8 (3) ◽  
pp. 127-139
Author(s):  
Insik Chun ◽  
In-Ki Min ◽  
Yongchim Min ◽  
Byungcheol Oh ◽  
Jaeseol Shim
Keyword(s):  
Single Point ◽  
Experimental Results ◽  
Mooring Line ◽  
Regular Wave ◽  
Experimental Conditions ◽  
Wave Observation ◽  
Exciting Forces ◽  
Set Up ◽  
Heave Motion

The prediction of the performance of a wave observation buoy is very important to acquire both in-situ security and good observation quality. In the present study, a numerical method was set up to analyze the dynamic interaction of a spherical buoy with its single point mooring line subject to regular wave conditions. The method was applied to the condition of an existing hydraulic experiment, producing results that are well compatible with experimental results within the limited accuracy of the available data. It was argued that some discrepancies between the numerical and experimental results might be due to the uncertainties of the wave exciting forces acting on the buoy and the experimental conditions of mooring line. The method was finally applied to demonstrate two practical issues related to in-situ wave height measurements; the effect of buoy size on resulting heave motion and the aspect of the numerical integration of heave acceleration to get wave profile.

Thermal Degradation of Green Asparagus Texture

1997 ◽  
Vol 60 (3) ◽  
pp. 315-320 ◽  
Author(s):  
CARMEN RODRIGO ◽  
MIGUEL RODRIGO ◽  
SUSANA FISZMAN ◽  
TERESA SÁNCHEZ
Keyword(s):  
Single Point ◽  
Experimental Conditions ◽  
Cutting Resistance ◽  
First Order ◽  
First Order Kinetics ◽  
Press Method ◽  
The Wire ◽  
Shear Press ◽  
Kinetics Of ◽  
Green Asparagus

A cutting cell was developed to evaluate the texture of green asparagus by measuring its resistance to being cut with a wire. The cell was used in conjunction with a universal texturometer and improved on the single-point method of the Wilder fibrometer. Experimental conditions were determined for using the cell to measure the cutting resistance of asparagus subjected to different extents of heat treatment. Better discrimination between samples was obtained than with a Kramer cell. The fresh asparagus spears. were heated at temperatures between 70 and 100°C for different lengths of time and the kinetics of the degradation of texture was studied. A biphasic (two-component) behavior was observed with each component displaying first-order kinetics, The kinetic parameters calculated by measuring the texture with the wire cell (cutting at a position 5 em from the tip of the asparagus) were Eaa = 9.56 and Eab = 20.43 kcal/mol (activation energy for components A and B), and ka85 = 1.047 and kb85 = 0.057 min−1 (rate constants for A and B of asparagus heated at 85°C). When the texture was determined by measuring the shear force with a Kramer cell, the parameters estimated were Eaa = 23.41 and Eab = 18.32 kcal/mol, and ka85 = 0.25 and kb85 = 0.025 min−1 Both the wire cell cutting method and the Kramer shear-press method are suitable for evaluating the degree of thermal softening of green asparagus heated to temperatures between 70 and 100°C.

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