scholarly journals A Review of Different Aspects of Off-Earth Drilling

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7351
Author(s):  
Dariusz Knez ◽  
Mitra Khalilidermani
Keyword(s):  
Power Systems ◽  
Modern Technology ◽  
Second Phase ◽  
Private Space ◽  
Space Tourism ◽  
Drilling Tools ◽  
Future Space ◽  
Planetary Bodies ◽  
Near Term

Off-Earth drilling may be assumed as the second phase of space exploration to discover the unrevealed subsurface on the planetary bodies. It accelerates future space objectives such as in-situ propellant production, mineral exploitation, and space tourism. Owing to the rampant progress in modern technology, the new drill tools mounted on the sophisticated robots are capable to drill the planetary regolith dispersed on the celestial objects; however, formidable obstacles such as microgravity, vacuum condition, and temperature fluctuation as well as the weight limitation, lack of real-time drilling analysis, and remote robot-operator communication impose pressing restrictions on the quick development of space drilling tools. In this study, research on the past and present aspects of off-Earth drilling has been implemented to illuminate the horizon of this technology in the near-term future. The context encompasses a detailed description of the limitations, applications and mechanisms of the different drilling techniques adopted for planetary bodies. A particular emphasis is put on the hydraulic power systems which have not been satisfactorily deployed in off-Earth drilling yet. The research strives to glance over the pivotal aspects of off-Earth drilling to contribute to the future drilling programs planned by the national and private space agencies.

scholarly journals A Concept Study on Advanced Radioisotope Solid Solutions and Mixed-Oxide Fuel Forms for Future Space Nuclear Power Systems

2021 ◽  
pp. 1-9
Author(s):  
Richard M. Ambrosi ◽  
Daniel P. Kramer ◽  
Emily Jane Watkinson ◽  
Ramy Mesalam ◽  
Alessandra Barco
Keyword(s):  
Power Systems ◽  
Solid Solutions ◽  
Mixed Oxide ◽  
Nuclear Power ◽  
Oxide Fuel ◽  
Concept Study ◽  
Mixed Oxide Fuel ◽  
Future Space ◽  
Space Nuclear Power

In-Situ Study of Ti/TiN Stability under Nitrogen Anneal

1999 ◽  
Vol 564 ◽  
Author(s):  
P. W. DeHaven ◽  
K. P. Rodbell ◽  
L. Gignac
Keyword(s):  
Annealing Temperature ◽  
Time Range ◽  
Second Phase ◽  
Transformation Rate ◽  
Transformation Mechanism ◽  
Second Stage ◽  
Transmission Electron ◽  
Reaction Proceeds ◽  
Two Stages

AbstractThe effectiveness of a TiN capping layer to prevent the conversion of α-titantium to titanium nitride when annealed in a nitrogen ambient has been studied over the temperature range 300–700°C using in-situ high temperature diffraction and transmission electron microscopy. Over the time range of interest (four hours), no evidence of Ti reaction was observed at 300°C. At 450°C. nitrogen was found to diffuse into the Ti to form a Ti(N) solid solution. Above 500°C the titanium is transformed to a second phase: however this reaction follows two different kinetic paths, depending on the annealing temperature. Below 600°C. the reaction proceeds in two stages, with the first stage consisting of Ti(N) formation, and the second stage consisting of the conversion of the Ti(N) with a transformation mechanism characteristic of short range diffusion (grain edge nucleation). Above 600°C, a simple linear transformation rate is observed.

scholarly journals Integrative analysis of <i>Geobacter</i> spp. and sulfate-reducing bacteria during uranium bioremediation

2012 ◽  
Vol 9 (3) ◽  
pp. 1033-1040 ◽  
Author(s):  
M. Barlett ◽  
K. Zhuang ◽  
R. Mahadevan ◽  
D. Lovley
Keyword(s):  
Sulfate Reducing Bacteria ◽  
Field Trials ◽  
Second Phase ◽  
Sulfate Reducing ◽  
Organic Electron ◽  
Poor Understanding ◽  
Key Factor ◽  
Reducing Bacteria ◽  
The Impact

Abstract. Enhancing microbial U(VI) reduction with the addition of organic electron donors is a promising strategy for immobilizing uranium in contaminated groundwaters, but has yet to be optimized because of a poor understanding of the factors controlling the growth of various microbial communities during bioremediation. In previous field trials in which acetate was added to the subsurface, there were two distinct phases: an initial phase in which acetate-oxidizing, U(VI)-reducing Geobacter predominated and U(VI) was effectively reduced and a second phase in which acetate-oxidizing sulfate reducing bacteria (SRB) predominated and U(VI) reduction was poor. The interaction of Geobacter and SRB was investigated both in sediment incubations that mimicked in situ bioremediation and with in silico metabolic modeling. In sediment incubations, Geobacter grew quickly but then declined in numbers as the microbially reducible Fe(III) was depleted whereas the SRB grow more slowly and reached dominance after 30–40 days. Modeling predicted a similar outcome. Additional modeling in which the relative initial percentages of the Geobacter and SRB were varied indicated that there was little to no competitive interaction between Geobacter and SRB when acetate was abundant. Further simulations suggested that the addition of Fe(III) would revive the Geobacter, but have little to no effect on the SRB. This result was confirmed experimentally. The results demonstrate that it is possible to predict the impact of amendments on important components of the subsurface microbial community during groundwater bioremediation. The finding that Fe(III) availability, rather than competition with SRB, is the key factor limiting the activity of Geobacter during in situ uranium bioremediation will aid in the design of improved uranium bioremediation strategies.

Effect of mass transport along interfaces and grain boundaries on copper interconnect degradation

2004 ◽  
Vol 812 ◽  
Author(s):  
Ehrenfried Zschech ◽  
Moritz A. Meyer ◽  
Eckhard Langer
Keyword(s):  
Mass Transport ◽  
Grain Boundaries ◽  
Void Formation ◽  
Degradation Process ◽  
Copper Interconnects ◽  
Second Phase ◽  
Copper Interconnect ◽  
Void Evolution ◽  
Two Phases

AbstractIn-situ SEM electromigration studies were performed at fully embedded via/line interconnect structures to visualize the time-dependent void evolution in inlaid copper interconnects. Void formation, growth and movement, and consequently interconnect degradation, depend on both interface bonding and copper microstructure. Two phases are distinguished for the electromigration-induced interconnect degradation process: In the first phase, agglomerations of vacancies and voids are formed at interfaces and grain boundaries, and voids move along weak interfaces. In the second phase of the degradation process, they merge into a larger void which subsequently grows into the via and eventually causes the interconnect failure. Void movement along the copper line and void growth in the via are discontinuous processes, whereas their step-like behavior is caused by the copper microstructure. Directed mass transport along inner surfaces depends strongly on the crystallographic orientation of the copper grains. Electromigration lifetime can be drastically increased by changing the copper/capping layer interface. Both an additional CoWP coating and a local copper alloying with aluminum increase the bonding strength of the top interface of the copper interconnect line, and consequently, electromigration-induced mass transport and degradation processes are reduced significantly.

scholarly journals Benefits of Solar/Fossil Hybrid Gas Turbine Systems

1979 ◽  
Author(s):  
H. S. Bloomfield
Keyword(s):  
Power Systems ◽  
Gas Turbine ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Fuel Saving ◽  
Operational Mode ◽  
Fuel Savings ◽  
Cycle Systems ◽  
Potential Benefits ◽  
Near Term

The potential benefits of solar/fossil hybrid gas turbine power systems were assessed. Both retrofit and new systems were considered from the aspects of: cost of electricity, fuel conservation, operational mode, technology requirements, and fuels flexibility. Hybrid retrofit (repowering) of existing combustion (simple Brayton cycle) turbines can provide near-term fuel savings and solar experience, while new and advanced recuperated or combined-cycle systems may be an attractive fuel saving and economically competitive vehicle to transition from today’s gas- and oil-fired powerplants to other more abundant fuels.

Development of Computer Vision Technique for in Situ Soil Characterization

1996 ◽  
Vol 1526 (1) ◽  
pp. 86-97 ◽  
Author(s):  
Roman D. Hryciw ◽  
Scott A. Raschke
Keyword(s):  
Computer Vision ◽  
Vision System ◽  
Cohesionless Soil ◽  
Software Systems ◽  
Small Scale ◽  
Second Phase ◽  
Video Images ◽  
Subsurface Soil ◽  
Different Levels

Construction and rehabilitation of highways, tunnels, and bridges require detailed information about subsurface stratigraphy. This study presents development of a new method for characterizing subsurface soil in situ using computer vision. Hardware and software systems are integrated to obtain the grain-size distribution (GSD) of subsurface soils continuously with depth and to identify small-scale subsurface anomalies. Research is being conducted in three phases. The first phase consists of measuring the GSD of detached cohesionless soil specimens in the laboratory from digital images obtained with a computer vision system (CVS). The second phase uses the CVS to develop image processing and analysis techniques to classify soil assemblies in the laboratory and identify subsurface anomalies by simulating the manner in which images will be acquired in situ. A texture analysis approach has been developed that can detect changes in stratigraphy. The technique has been successful in identifying different types of dry, uniformly graded soils. Finally, a subsurface vision probe is being designed and constructed that will capture video images at three different levels of magnification continuously with depth.

Fracture Mechanisms in Laminates in the Alumina - Titania System

2005 ◽  
Vol 290 ◽  
pp. 208-213 ◽  
Author(s):  
S. Bueno ◽  
Carmen Baudín
Keyword(s):  
High Strength ◽  
Fracture Mechanisms ◽  
Second Phase ◽  
Alumina Layer ◽  
Laminated Structure ◽  
Stable Crack Propagation ◽  
Aluminium Titanate ◽  
Intermediate Layers ◽  
Composite Layers

Alumina (Al2O3)-aluminium titanate (Al2TiO5) composites present higher toughness than alumina materials but rather low strength due to microcracking. Laminates in which a flaw tolerant material is located between high strength layers is one way to overcome this problem. In this work, the fracture behaviour of a laminated structure constituted by five layers, where low residual stresses are expected, is studied. In this system, external and central layers of monophase alumina with high strength were combined with intermediate layers of alumina with 10vol.% of aluminium titanate. In the monophase alumina layers, an additional "in situ" formed layer of about 200 µm, constituted by large (@10µm) grains was found, close to the composite layers. The laminated structure presented semistable behaviour during SENVB tests for conditions in which stable crack propagation is not predicted for small grain sized alumina materials. Toughening mechanisms related to thermal expansion mismatch between matrix and second phase in the composite layers and crack bridging in the large grain sized alumina layer were identified.

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