scholarly journals The impact of laser control on the porosity and microstructure of selective laser melted nickel superalloy 718

2021 ◽  
pp. 100211
Author(s):  
Travis E. Shelton ◽  
Gregory R. Cobb ◽  
Carl R. Hartsfield ◽  
Benjamin M. Doane ◽  
Cayla C. Eckley ◽  
...  
Keyword(s):  
Nickel Superalloy ◽  
Laser Control ◽  
The Impact

scholarly journals Impact of Baseline Central Retinal Thickness on Outcomes in the VIVID-DME and VISTA-DME Studies

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Edoardo Midena ◽  
Mark Gillies ◽  
Todd A. Katz ◽  
Carola Metzig ◽  
Chengxing Lu ◽  
...  
Keyword(s):  
Treatment Effect ◽  
Retinal Thickness ◽  
Continuous Variable ◽  
Central Retinal Thickness ◽  
Link Type ◽  
Intravitreal Aflibercept ◽  
Laser Control ◽  
Post Hoc ◽  
The Impact ◽  
Anatomical Outcomes

Purpose. To report the impact of baseline central retinal thickness (CRT) on outcomes in patients with diabetic macular edema (DME) in VIVID-DME and VISTA-DME. Methods. Post hoc analyses of two randomized controlled trials in which 862 DME patients were randomized 1 : 1 : 1 to treatment with intravitreal aflibercept 2.0 mg every 4 weeks (2q4), intravitreal aflibercept 2.0 mg every 8 weeks after five initial monthly doses (2q8), or macular laser photocoagulation at baseline and as needed. We compared visual and anatomical outcomes in subgroups of patients with baseline CRT < 400 μm and ≥400 μm. Results. At weeks 52 and 100, outcomes with intravitreal aflibercept 2q4 and 2q8 were superior to those in laser control-treated patients regardless of baseline CRT. When looked at in a binary fashion, the treatment effect of intravitreal aflibercept versus laser was not significantly better in the ≥400 μm than the <400 μm group; when looked at as a continuous variable, baseline CRT seemed to have an impact on the treatment effect of intravitreal aflibercept versus laser. Conclusions. Post hoc analyses of VIVID-DME and VISTA-DME demonstrated the benefits of intravitreal aflibercept treatment in DME patients with baseline CRT < 400 μm and ≥400 μm. This trial is registered with NCT01331681 and NCT01363440.

Process Design for Superalloys Sheet Rotary Forming

2020 ◽  
Vol 985 ◽  
pp. 91-96
Author(s):  
Krzysztof Zaba ◽  
Sandra Puchlerska ◽  
Tomasz Pieja ◽  
Jaroslaw Pyzik
Keyword(s):  
Process Design ◽  
Elevated Temperatures ◽  
Nickel Superalloy ◽  
Inconel 625 ◽  
Quality Factors ◽  
Forming Process ◽  
Plastic Properties ◽  
Temperature Oxidation ◽  
Wide Range ◽  
The Impact

Inconel 625 is a nickel superalloy, characterized by high fatigue strength. The alloy is resistant to a wide range of corrosive environments, including high-temperature oxidation. For this reason, it is an attractive material for the chemical, shipbuilding and aviation industries. Inconel 625 alloy is designed for plastic working. However, the significant difficulty is the appropriate process design, due to the high deformation resistance. In order to improve the plastic properties of the alloy, processing at elevated temperatures is practiced. In this work, attempts were made to implement rotary forming process of Inconel 625 superalloy. For this purpose, an experiment was designed, investigating the impact of three variables on the process – feed rate, spinning rate and heating. For the tests were used Inconel 625 metal plates in the shape of discs. Axial-symmetrical products were formed, using a spinning machine. The geometry of the products according to selected quality factors was investigated. Optimal process parameters were chosen using multivariate statistical optimization. These parameters will be used to set up processes to obtain product that meets quality requirements.

scholarly journals The Influence of Impurities in Feed Ingots on the Quality of Castings Made from Nickel Superalloy IN-713C

2013 ◽  
Vol 13 (4) ◽  
pp. 5-8 ◽  
Author(s):  
F. Binczyk ◽  
J. Cwajna ◽  
M. Sozańska ◽  
P. Gradoń
Keyword(s):  
Thermal Analysis ◽  
Liquid Alloy ◽  
Nickel Superalloy ◽  
Vacuum Furnace ◽  
Interdendritic Space ◽  
Metallic Inclusions ◽  
Shrinkage Cavities ◽  
The Impact ◽  
Influence Of Impurities

Abstract The paper presents the results of research on the impact of impurities in the feed ingots (master heat) on the precipitation of impurities in the ATD thermal analysis probe castings. This impurities occur mostly inside shrinkage cavities and in interdendritic space. Additionally, insufficient filtration of liquid alloy during pouring promotes the transfer of impurities into the casting. The technology of melting superalloys in vacuum furnace prevents the removal of slag from the surface of molten metal. Because of that, the effective method of quality assessment of feed ingots in order to evaluate the existence of impurities is needed. The effectiveness of ATD analysis in evaluation of purity of feed ingots was researched. In addition the similarities of non-metallic inclusions in feed ingots and in castings were observed.

scholarly journals CONTROL OF QUANTUM SYSTEMS

2003 ◽  
Vol 17 (28) ◽  
pp. 5397-5411 ◽  
Author(s):  
JOHN W. CLARK ◽  
DENNIS G. LUCARELLI ◽  
TZYH-JONG TARN
Keyword(s):  
Quantum Computation ◽  
Quantum Control ◽  
Sufficient Conditions ◽  
The State ◽  
Dimensional Manifold ◽  
Infinite Dimensional ◽  
Many Body Theory ◽  
Laser Control ◽  
Control Of Quantum Systems ◽  
The Impact

A quantum system subject to external fields is said to be controllable if these fields can be adjusted to guide the state vector to a desired destination in the state space of the system. Fundamental results on controllability are reviewed against the background of recent ideas and advances in two seemingly disparate endeavours: (i) laser control of chemical reactions and (ii) quantum computation. Using Lie-algebraic methods, sufficient conditions have been derived for global controllability on a finite-dimensional manifold of an infinite-dimensional Hilbert space, in the case that the Hamiltonian and control operators, possibly unbounded, possess a common dense domain of analytic vectors. Some simple examples are presented. A synergism between quantum control and quantum computation is creating a host of exciting new opportunities for both activities. The impact of these developments on computational many-body theory could be profound.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Organic Syntheses During the Impact of a Comet with a Gaseous Planet

1997 ◽  
Vol 161 ◽  
pp. 189-195
Author(s):  
Cesare Guaita ◽  
Roberto Crippa ◽  
Federico Manzini
Keyword(s):  
Polymeric Material ◽  
Molecular Form ◽  
Parent Compound ◽  
Blue Filter ◽  
Organic Syntheses ◽  
The Impact

AbstractA large amount of CO has been detected above many SL9/Jupiter impacts. This gas was never detected before the collision. So, in our opinion, CO was released from a parent compound during the collision. We identify this compound as POM (polyoxymethylene), a formaldehyde (HCHO) polymer that, when suddenly heated, reformes monomeric HCHO. At temperatures higher than 1200°K HCHO cannot exist in molecular form and the most probable result of its decomposition is the formation of CO. At lower temperatures, HCHO can react with NH3 and/or HCN to form high UV-absorbing polymeric material. In our opinion, this kind of material has also to be taken in to account to explain the complex evolution of some SL9 impacts that we observed in CCD images taken with a blue filter.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

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