Tailoring the preferable orientation relationship and shape of α-FeSi2 nanocrystals on Si(001): the impact of gold and the Si/Fe flux ratio, and the origin of α/Si boundaries

CrystEngComm ◽  
2020 ◽  
Vol 22 (23) ◽  
pp. 3943-3955
Author(s):  
Ivan A. Tarasov ◽  
Tatiana E. Smolyarova ◽  
Ivan V. Nemtsev ◽  
Ivan A. Yakovlev ◽  
Mikhail N. Volochaev ◽  
...  
Keyword(s):  
Orientation Relationship ◽  
Flux Ratio ◽  
Orientation Relationships ◽  
Free Standing ◽  
The Impact

An approach for tuning the preferable orientation relationships and shapes of free-standing α-FeSi2 nanocrystals was demonstrated on a Si(001) surface.

Hydrogen Blending Into Ansaldo Energia AE94.3A Gas Turbine: High Pressure Tests, Field Experience and Modelling Considerations

2021 ◽  
Author(s):  
A. Ciani ◽  
L. Tay-Wo-Chong ◽  
A. Amato ◽  
E. Bertolotto ◽  
G. Spataro
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Power Plants ◽  
Flame Structure ◽  
Flux Ratio ◽  
Fuel Blends ◽  
Pressure Tests ◽  
Fuel Staging ◽  
Combustion Tests ◽  
The Impact

Abstract Fuel flexibility in gas turbine development has become increasingly important and modern engines need to cope with a broad variety of fuels. The target to operate power plants with hydrogen-based fuels and low emissions will be of paramount importance in a future focusing on electric power decarbonization. Ansaldo Energia AE94.3A engine acquired broad experience with operation of various natural gas and hydrogen fuel blends, starting in 2006 in the Brindisi (Italy) power plant. Based on the exhaustive experience acquired in the field, this paper describes the latest advancements characterizing the operation of the AE94.3A burner with high pressure combustion tests adding hydrogen blends ranging from 0 to 40% in volume. The interpretation of the test results is supported by reactive and non-reactive simulations describing the effects of varying fuel reactivity on the flame structure as well as the impact of fuel / air momentum flux ratio on the fuel / air interaction and fuel distribution in the combustion chamber. As expected, increasing amounts of hydrogen in the fuel are also associated with higher amounts of NOx production, however this effect could be countered by optimization of the fuel staging strategy, based on the mentioned CFD considerations and feedback from high pressure tests.

Stress Evaluation on Hetero-Epitaxial 3C-SiC Film on (100) Si Substrates

2012 ◽  
Vol 717-720 ◽  
pp. 521-524 ◽  
Author(s):  
Ruggero Anzalone ◽  
M. Camarda ◽  
C. Locke ◽  
J. Carballo ◽  
N. Piluso ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Process ◽  
Film Growth ◽  
Raman Shift ◽  
Fundamental Parameter ◽  
Free Standing ◽  
Si Substrates ◽  
Shift Analysis ◽  
Hydrogen Carrier ◽  
The Impact

SiC is a candidate material for micro- and nano-electromechanical systems (MEMS and NEMS). In order to understand the impact that the growth rate has on the residual stress of CVD-grown 3C-SiC hetero-epitaxial films on Si substrates, growth experiments were performed and the resulting stress was evaluated. Film growth was performed using a two-step growth process with propane and silane as the C and Si precursors in hydrogen carrier gas. The film thickness was held constant at ~2.5 µm independent of the growth rate so as to allow for direct films comparison as a function of the growth rate. Supported by profilometry, Raman and micro-machined free-standing structures, this study shows that the growth rate is a fundamental parameter for low-defect and low-stress hetero-epitaxial growth process of 3C-SiC on Si substrates. Stress analysis performed by modify Stoney’s equation trough optical curvature measurement, Raman shift analysis and micro-machining of free-standing structures that shows apparent disagreement about the nature of the stress. These odds between the experimental data can be explained assuming a strong stress field located in the substrate and related to defects generated in the silicon during the growth process.

scholarly journals Less than the sum of its parts: the dust-corrected H α luminosity of star-forming galaxies explored at different spatial resolutions with MaNGA and MUSE

2020 ◽  
Vol 498 (3) ◽  
pp. 4205-4221
Author(s):  
N Vale Asari ◽  
V Wild ◽  
A L de Amorim ◽  
A Werle ◽  
Y Zheng ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Formation Rate ◽  
Flux Ratio ◽  
Star Forming ◽  
The Galaxy ◽  
Nearby Galaxies ◽  
Point To Point ◽  
Dust Attenuation ◽  
The Impact ◽  
Lower Limits

ABSTRACT The H α and H β emission-line luminosities measured in a single integrated spectrum are affected in non-trivial ways by point-to-point variations in dust attenuation in a galaxy. This work investigates the impact of this variation when estimating global H α luminosities corrected for the presence of dust by a global Balmer decrement. Analytical arguments show that the dust-corrected H α luminosity is always underestimated when using the global H α/H β flux ratio to correct for dust attenuation. We measure this effect on 156 face-on star-forming galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey. At 1–2 kpc spatial resolution, the effect is small but systematic, with the integrated dust-corrected H α luminosity underestimated by 2–4 per cent (and typically not more than by 10 per cent), and depends on the specific star formation rate of the galaxy. Given the spatial resolution of MaNGA, these are lower limits for the effect. From Multi Unit Spectroscopic Explorer (MUSE) observations of NGC 628 with a resolution of 36 pc, we find the discrepancy between the globally and the point-by-point dust-corrected H α luminosity to be 14 ± 1 per cent, which may still underestimate the true effect. We use toy models and simulations to show that the true difference depends strongly on the spatial variance of the H α/H β flux ratio, and on the slope of the relation between H αluminosity and dust attenuation within a galaxy. Larger samples of higher spatial resolution observations are required to quantify the dependence of this effect as a function of galaxy properties.

Can Advertising Copy Make FSI Coupons More Effective?

1997 ◽  
Vol 34 (4) ◽  
pp. 473-484 ◽  
Author(s):  
France Leclerc ◽  
John D. C. Little
Keyword(s):  
Brand Loyalty ◽  
Laboratory Experiments ◽  
Product Category ◽  
Consumer Attitudes ◽  
Separate Analysis ◽  
Free Standing ◽  
Packaged Goods ◽  
Print Advertisement ◽  
Per Se ◽  
The Impact

Packaged goods manufacturers distribute cents-off coupons in freestanding inserts (FSIs) in newspapers. Free-standing insert coupons are typically composed of two parts: the coupon per se and a print advertisement. Using two laboratory experiments and a separate analysis of coupon measurements from scanner panels, the authors investigate whether the content of the print advertisement influences the effectiveness of the coupon. Theoretical arguments suggest that the impact on consumer attitudes will depend on the executional cues of the copy, the brand loyalty of the consumers, and the consumer's involvement with the product category. The results support the theoretical framework and suggest that it is possible to make FSI coupons more effective by choosing appropriate executional cues for their advertising copy.

Quantitative Analysis of Variant Selection and Orientation Relationships during the γ-to-α Phase Transformation in Hot-Rolled TRIP Steels

2010 ◽  
Vol 89-91 ◽  
pp. 359-364 ◽  
Author(s):  
Loïc Malet ◽  
Pascal J. Jacques ◽  
Stéphane Godet
Keyword(s):  
Phase Transformation ◽  
Orientation Relationship ◽  
Hot Deformation ◽  
High Performance ◽  
Statistical Treatment ◽  
Phenomenological Theory ◽  
Variant Selection ◽  
Orientation Relationships ◽  
Α Phase ◽  
Hot Rolled

The orientation relationships that apply to the fcc (γ) – bcc (α) phase transformation in high-performance hot-rolled TRIP-aided steels were characterised by EBSD techniques. A statistical treatment of the experimental data allows the mean orientation relationship to be determined. This mean orientation relationship was compared to the models commonly proposed in the literature and confronted qualitatively to the predictions of the phenomenological theory of martensite crystallography (PTMC). The variant selection phenomenon was also characterized quantitatively at the level of individual austenite grains. The reconstruction of the EBSD maps evidences that bainite grows by packets in which the bainite laths share a common {111}γ plane in the austenite. This growth mechanism is not influenced by the prior hot deformation of the austenite. The hot deformation has a critical influence on the number of packets that forms. The analysis of the crystallographic features of the bainite packets reveals that all possible variants are formed in a packet, though in different proportions.

Effect of Cross-Flow Swirl on the Trajectory of Spray in an Annular Passage

2020 ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari
Keyword(s):  
Momentum Flux ◽  
High Speed ◽  
Air Flow ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Swirl Number ◽  
Flow Swirl ◽  
Air Stream ◽  
The Impact

Abstract This paper presents the experimental analysis of the impact of swirl number of cross-flowing air stream on liquid jet spray trajectory at a fixed air flow velocity of 42 m/s with the corresponding Mach number of 0.12. The experiments were conducted for 4 different swirl numbers (0, 0.2, 0.42 and 0.73) using swirl vanes at air inlet having angles of 0°, 15°, 30° and 45° respectively. Liquid to air momentum flux ratio (q) was varied from 5 to 25. High speed (@ 500 fps) images of the spray were captured and those images were processed using MATLAB to obtain the path of the spray at various momentum flux ratios. The results show interesting trends for the spray trajectory and the jet spread in swirling air flow. High swirling flows not only lead to spray with lower radial penetration due to sharp bending and disintegration of liquid jet, but also result in spray with high jet spread and spray area. Based on the results, correlations for the spray path have been proposed which incorporates the effects of the swirl number of the air flow.

scholarly journals Extinction in the 11.2 µm PAH band and the low L11.2/LIR in ULIRGs

2020 ◽  
Vol 497 (4) ◽  
pp. 4614-4625
Author(s):  
Antonio Hernán-Caballero ◽  
Henrik W W Spoon ◽  
Almudena Alonso-Herrero ◽  
Evanthia Hatziminaoglou ◽  
Georgios E Magdis ◽  
...  
Keyword(s):  
Star Formation ◽  
Equivalent Width ◽  
Flux Ratio ◽  
Width Ratio ◽  
Galactic Centre ◽  
Star Forming ◽  
Intrinsic Flux ◽  
Star Formation In Galaxies ◽  
The Impact ◽  
Small Dispersion

ABSTRACT We present a method for recovering the intrinsic (extinction-corrected) luminosity of the 11.2 μm PAH band in galaxy spectra. Using 105 high S/N Spitzer/IRS spectra of star-forming galaxies, we show that the equivalent width ratio of the 12.7 and 11.2 μm PAH bands is independent on the optical depth (τ), with small dispersion (∼5 per cent) indicative of a nearly constant intrinsic flux ratio Rint = (f12.7/f11.2)int = 0.377 ± 0.020. Conversely, the observed flux ratio, Robs = (f12.7/f11.2)obs, strongly correlates with the silicate strength (Ssil) confirming that differences in Robs reflect variation in τ. The relation between Robs and Ssil reproduces predictions for the Galactic Centre extinction law but disagrees with other laws. We calibrate the total extinction affecting the 11.2 μm PAH from Robs, which we apply to another sample of 215 galaxies with accurate measurements of the total infrared luminosity (LIR) to investigate the impact of extinction on L11.2/LIR. Correlation between L11.2/LIR and Robs independently on LIR suggests that increased extinction explains the well-known decrease in the average L11.2/LIR at high LIR. The extinction-corrected L11.2 is proportional to LIR in the range LIR = 109–1013 L⊙. These results consolidate L11.2 as a robust tracer of star formation in galaxies.

Orientation Studies of α-Al(Fe,Mn)Si Dispersoids in 3xxx Al Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 39-44 ◽  
Author(s):  
Astrid Marie Flattum Muggerud ◽  
Yan Jun Li ◽  
Randi Holmestad
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Orientation Relationship ◽  
Aluminum Matrix ◽  
Al Alloys ◽  
Orientation Relationships ◽  
The Matrix ◽  
The Common ◽  
Habit Planes ◽  
Al Matrix

Dispersoids are important in 3xxx Al alloys, influencing mechanical properties, texture and recrystallization. In this work α-Al (Fe,Mn)Si dispersoids have been studied after low temperature homogenisation. The common orientation relationship between dispersoids and Al matrix has been reported in earlier studies. Here a systematic study on the orientation relationship and its exceptions is presented. It is found that most of the dispersoids follow the common orientation relationship, [1-1 1] α //[1-1 1]Al , (5-2 -7 ) α //(0 1 1)Al . Here the dispersoids are semi coherent with the Aluminum matrix. Different morphologies and habit planes are possible. Deviations from the most commonly observed orientation relationships are presented and discussed, to underline the complexity of the phase and its relation to the matrix.

Geometrical Modification of the Unsteady Pressure to Reduce Low-Pressure Turbine Flutter

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Christian Peeren ◽  
Konrad Vogeler
Keyword(s):  
Turbine Blade ◽  
Local Stability ◽  
Free Standing ◽  
Unsteady Pressure ◽  
Low Pressure Turbine ◽  
Physical Mechanisms ◽  
Local Modification ◽  
Blade Section ◽  
Turbine Design ◽  
The Impact

In this work, the impact of the airfoil shape on flutter is investigated. Flutter occurs when the blade structure is absorbing energy from its surrounding fluid leading to hazardous amplification of vibrations. The key for a more stable design is the local modification of the blade motion induces unsteady pressure, which is responsible for local stability. Especially for free-standing blades, where most exciting aerodynamic work transfer is found at the upper tip sections, a reshaping of the airfoil is expected to beneficially influence stability. Two approaches are pursued in this work. This first approach is based on flow physics considerations. The unsteady pressure field is decomposed into four physical mechanisms or effects and each effect investigated. The second approach is used to validate the conclusions made in the theoretical part by numerical optimizing the geometry of a representative turbine blade. Selected optimized designs are picked and compared with each other in terms of local stability, aerodynamics, and robustness with respect to the boundary conditions. Both approaches are applied for a freestanding and interlocked turbine blade section. The found design potential is discussed and the link to the differences mechanisms, introduced in the first part, established. Based on the observations made, design recommendations are made for a flutter-reduced turbine design.

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