scholarly journals H I Emission and Absorption in the Southern Galactic Plane Survey

2001 ◽  
Vol 18 (1) ◽  
pp. 84-90 ◽  
Author(s):  
N. M. McClure-Griffiths ◽  
John M. Dickey ◽  
B. M. Gaensler ◽  
A. J. Green ◽  
R. F. Haynes ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Radio Telescope ◽  
Large Scale ◽  
Galactic Plane ◽  
Pilot Project ◽  
Small Scale ◽  
Preliminary Results ◽  
Test Region ◽  
Scale Structures ◽  
Spatial Power Spectrum

AbstractWe present preliminary results from the Southern Galactic Plane Survey (SGPS) Test Region and Parkes data. As part of the pilot project for the Southern Galactic Plane Survey, observations of a Test Region (325·5° ≤l ≤ 333·5°; −0·5° ≤ b ≤ 3·5°) were completed in December 1998. Single-dish observations of the full survey region (253° ≤ l ≤ 358 ° |b| ≤ 1°) with the Parkes Radio Telescope were completed in March 2000. We present a sample of SGPS H I data, with particular attention to the smallest-and largest-scale structures seen in absorption and emission, respectively. On the large scale, we detect many prominent H I shells. On the small scale, we note extremely compact, cold clouds seen in H I self-absorption. We explore how these two classes of objects probe opposite ends of the H I spatial power spectrum.

SCINTILLATION EFFECTS AND THE SPATIAL POWER SPECTRUM OF SCATTERED RADIO WAVES IN THE IONOSPHERIC F REGION

2017 ◽  
Vol 13 (1) ◽  
pp. 4593-4604 ◽  
Author(s):  
George Vakhtang Jandieri ◽  
Natalia Zhukova ◽  
Zhuzhuna Diasamidze ◽  
Mzia Diasamidze
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Phase Fluctuation ◽  
Density Fluctuations ◽  
Magnetized Plasma ◽  
Small Scale ◽  
Radio Waves ◽  
F Region ◽  
Diffraction Effects ◽  
Spatial Power Spectrum

Differential equation for two-dimensional spectral function of the phase fluctuation is derived using the modify smooth perturbation method. Second order statistical moments of the phase fluctuations are calculated taking into account polarization coefficients of both ordinary and extraordinary waves in the turbulent collision magnetized plasma and the diffraction effects. Analytical and numerical investigations in the ionospheric F region are based on the anisotropic Gaussian and power law spectral functions of electron density fluctuations including both the field-aligned anisotropy and field-perpendicular anisotropy of the plasma irregularities. Scintillation effects in this region are investigated for the small-scale ionospheric irregularities. The large-scale background plasma structures are responsible for the double-humped shape in the spatial power spectrum taking into account diffraction effects. Numerical calculations are based on the experimental data of the navigation satellites. 

scholarly journals Design of Compliant Joints for Large Scale Structures

2020 ◽  
Author(s):  
Angela Nastevska ◽  
Jovana Jovanova ◽  
Mary Frecker
Keyword(s):  
Large Scale ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Small Scale ◽  
Nonlinear Bending ◽  
Large Scale Structures ◽  
Compliant Joints ◽  
Scale Structures ◽  
High Level ◽  
Novel Design

Abstract Large scale structures can benefit from the design of compliant joints that can provide flexibility and adaptability. A high level of deformation is achieved locally with the design of flexures in compliant mechanisms. Additionally, by introducing contact-aided compliant mechanisms, nonlinear bending stiffness is achieved to make the joints flexible in one direction and stiff in the opposite one. All these concepts have been explored in small scale engineering design, but they have not been applied to large scale structures. In this paper the design of a large scale compliant mechanism is proposed for novel design of a foldable shipping container. The superelasticity of nickel titanium is shown to be beneficial in designing the joints of the compliant mechanism.

scholarly journals Climate SPHINX: evaluating the impact of resolution and stochastic physics parameterisations in climate simulations

2016 ◽  
Author(s):  
Paolo Davini ◽  
Jost von Hardenberg ◽  
Susanna Corti ◽  
Hannah M. Christensen ◽  
Stephan Juricke ◽  
...  
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Rainfall Variability ◽  
Pilot Project ◽  
Small Scale ◽  
Low Resolution ◽  
Climate Simulations ◽  
Advanced Computing ◽  
The Impact ◽  
Stochastic Physics

Abstract. The Climate SPHINX (Stochastic Physics HIgh resolutioN eXperiments) project is a comprehensive set of ensemble simulations aimed at evaluating the sensitivity of present and future climate to model resolution and stochastic parameterisation. The EC-Earth Earth-System Model is used to explore the impact of stochastic physics in a large ensemble of 30-year climate integrations at five different atmospheric horizontal resolutions (from 125 km up to 16 km). The project includes more than 120 simulations in both a historical scenario (1979–2008) and a climate change projection (2039–2068), together with coupled transient runs (1850–2100). A total of 20.4 million core hours have been used, made available from a single year grant from PRACE (the Partnership for Advanced Computing in Europe), and close to 1.5 PBytes of output data have been produced on SuperMUC IBM Petascale System at the Leibniz Supercomputing Center (LRZ) in Garching, Germany. About 140 TBytes of post-processed data are stored on the CINECA supercomputing center archives and are freely accessible to the community thanks to an EUDAT Data Pilot project. This paper presents the technical and scientific setup of the experiments, including the details on the forcing used for the simulations performed, defining the SPHINX v1.0 protocol. In addition, an overview of preliminary results is given: an improvement in the simulation of Euro-Atlantic atmospheric blocking following resolution increases is observed. It is also shown that including stochastic parameterisation in the low resolution runs helps to improve some aspects of the tropical climate – specifically the Madden-Julian Oscillation and the tropical rainfall variability. These findings show the importance of representing the impact of small scale processes on the large scale climate variability either explicitly (with high resolution simulations) or stochastically (in low resolution simulations).

scholarly journals Interferometric observations of the small-scale structure of Galactic neutral hydrogen

1985 ◽  
Vol 106 ◽  
pp. 321-322
Author(s):  
J. Crovisier ◽  
J. M. Dickey
Keyword(s):  
Power Spectrum ◽  
Dynamic Range ◽  
Neutral Hydrogen ◽  
Scale Structure ◽  
Small Scale ◽  
Turbulence Spectrum ◽  
Small Scale Structure ◽  
Image Position ◽  
Spatial Power Spectrum

The small-scale structure of galactic neutral hydrogen may be statistically described by the spatial power spectrum of the 21-cm line. This latter may be readily observed by interferometer arrays since it is the squared modulus of the visibility function. We have observed the , region with the Westerbork Synthesis Radio Telescope (Crovisier and Dickey, 1983). Brightness fluctuations of the 21-cm line were detected in this region on scales as small as 1.7 arcmin (corresponding to less than 5 pc). The Westerbork observations, combined with single-dish observations made at Nançay and Arecibo, allow determination of the spatial power spectrum over a dynamic range of about 106 in intensity. The spectrum follows roughly a power law with indices ~ −3 to −2. An interpretation in terms of the turbulence spectrum is proposed by Dickey (1985).

scholarly journals The White-Light, Far-Red (600-700 nm) and Emission Coronae at the July 11, 1991 Eclipse

1994 ◽  
Vol 154 ◽  
pp. 211-215
Author(s):  
V. Rušin ◽  
M. Rybanský ◽  
M Minarovjech ◽  
T. Pintér
Keyword(s):  
White Light ◽  
Light Emission ◽  
Scattered Light ◽  
White Light Emission ◽  
Small Scale ◽  
Preliminary Results ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures ◽  
Multiwavelength Observations

Preliminary results of the analysis of the white-light, emission (green and red), and far red (600-700 nm) corona during the July 11, 1991 eclipse are given. Even though the corona is of nearly-maximum type, four different principal coronal structures are seen, combined with faint, small-scale structures (loops, arches, cavities, voids or plasmoids). Scattered light is seen up to 10 R⊙ in helmet streamers. The Ludendorff index of the corona shape turns out to be a + b = −0.02, and the estimated brightness of JK = 1.47 × 10–6B⊙. Some aspects of multiwavelength observations are discussed.

Three-dimensional conditional structure of a high-Reynolds-number turbulent boundary layer

2011 ◽  
Vol 673 ◽  
pp. 255-285 ◽  
Author(s):  
N. HUTCHINS ◽  
J. P. MONTY ◽  
B. GANAPATHISUBRAMANI ◽  
H. C. H. NG ◽  
I. MARUSIC
Keyword(s):  
Skin Friction ◽  
High Reynolds Number ◽  
Large Scale ◽  
Three Dimensional ◽  
Streamwise Velocity ◽  
Small Scale ◽  
Large Scale Structures ◽  
Local Mean ◽  
Scale Structures ◽  
High Reynolds

An array of surface hot-film shear-stress sensors together with a traversing hot-wire probe is used to identify the conditional structure associated with a large-scale skin-friction event in a high-Reynolds-number turbulent boundary layer. It is found that the large-scale skin-friction events convect at a velocity that is much faster than the local mean in the near-wall region (the convection velocity for large-scale skin-friction fluctuations is found to be close to the local mean at the midpoint of the logarithmic region). Instantaneous shear-stress data indicate the presence of large-scale structures at the wall that are comparable in scale and arrangement to the superstructure events that have been previously observed to populate the logarithmic regions of turbulent boundary layers. Conditional averages of streamwise velocity computed based on a low skin-friction footprint at the wall offer a wider three-dimensional view of the average superstructure event. These events consist of highly elongated forward-leaning low-speed structures, flanked on either side by high-speed events of similar general form. An analysis of small-scale energy associated with these large-scale events reveals that the small-scale velocity fluctuations are attenuated near the wall and upstream of a low skin-friction event, while downstream and above the low skin-friction event, the fluctuations are significantly amplified. In general, it is observed that the attenuation and amplification of the small-scale energy seems to approximately align with large-scale regions of streamwise acceleration and deceleration, respectively. Further conditional averaging based on streamwise skin-friction gradients confirms this observation. A conditioning scheme to detect the presence of meandering large-scale structures is also proposed. The large-scale meandering events are shown to be a possible source of the strong streamwise velocity gradients, and as such play a significant role in modulating the small-scale motions.

SMALL SCALE PILOT PROJECT AS A TOOL FOR PLANNING LARGE SCALE RESTORATION

2008 ◽  
Vol 2008 (1) ◽  
pp. 1163-1169
Author(s):  
Leslie J. Craig ◽  
Tom Pride
Keyword(s):  
Large Scale ◽  
Oyster Reef ◽  
Pilot Project ◽  
Lessons Learned ◽  
Small Scale ◽  
Pilot Studies ◽  
Restoration Project ◽  
Survival And Growth ◽  
Oyster Restoration

ABSTRACT The use of pilot studies can be a useful tool in determining the most appropriate location, method and design for a large scale restoration project. This paper provides a case study where Trustees implemented a small pilot project and feasibility study to determine the best approach for a large scale oyster reef creation project. While the specific case study is the result of a CERCLA settlement (Alafia River Acid Spill of 1997), this model is transferable to other instances where Trustees are scoping for the most appropriate sites and methods to conduct settlement funded restoration. The Restoration Plan and Environmental Assessment on which the case settlement was based called for creation of approximately 4 acres of oyster reef in addition to 4 acres of estuarine marsh restoration. Through an initial scoping process, the Trustees determined that more information was needed to select the most appropriate locations and techniques to implement the large scale oyster restoration project. The Trustees identified 3 general locations with potential for larger scale oyster reef creation. A portion of settlement funding was used to contract for construction and monitoring of an oyster reef pilot project to examine the efficacy of oyster reef construction at the three locations using 4 different cultch materials. At each of the locations, 4 small reefs (approximately 75’ × 20’) were constructed and monitored for spat set, oyster survival and growth as well as subsidence. A baseline construction report and final monitoring report detailed the results. In addition, a separate report was completed that outlined the feasibility of constructing a 4 acre oyster reef in Hillsborough Bay, FL. This report included several construction considerations such as local sources and costs of cultch materials, shipping/transport, staging areas, construction equipment as well as potential local contractors. This paper reports the results of the oyster pilot project and feasibility report as well as lessons learned from each approach.

Observation of Large-Scale Structures in Unsaturated Materials

1990 ◽  
Vol 195 ◽  
Author(s):  
J. E. Maneval ◽  
M.J. Mccarthy ◽  
S. Whitaker
Keyword(s):  
Magnetic Resonance Imaging ◽  
Nuclear Magnetic Resonance ◽  
Large Scale ◽  
Imaging Techniques ◽  
Image Data ◽  
Small Scale ◽  
Resonance Imaging ◽  
Specific System ◽  
Large Scale Structures ◽  
Scale Structures

ABSTRACTWe report here the use of nuclear magnetic resonance imaging in the observation of liquid-phase fraction distributions in a partially-wetted sample of glass beads. By combiningboth large- and small-scale imaging techniques, we can study the transition from local-averaged saturations to large-scale averaged saturations. The image data allows us to assess the utility of the large-scale measurements We comment on the reliability and generality of the measurements for our specific system.

scholarly journals Co-Rotating Interaction Regions in 2D Hot-Star Wind Models with Line-Driven Instability

1999 ◽  
Vol 169 ◽  
pp. 294-302 ◽  
Author(s):  
Stanley P. Owocki
Keyword(s):  
Large Scale ◽  
Source Function ◽  
Grid Method ◽  
Small Scale ◽  
Stellar Winds ◽  
Preliminary Results ◽  
Wind Variability ◽  
Wind Structure ◽  
Line Force ◽  
Interaction Regions

AbstractI review simulations of Co-rotating Interaction Regions (CIRs) in line-driven stellar winds. Previous CIR models have been based on a local, Sobolev treatment of the line-force, which effectively suppresses the strong, small-scale instability intrinsic to line-driving. Here I describe a new “3-ray-aligned-grid” method for computing the nonlocal, smooth-source-function line-force in 2D models that do include this line-driven instability. Preliminary results indicate that key overall features of large-scale CIRs can be quite similar in both Sobolev and non-Sobolev treatments, if the level of instability-generated wind structure is not too great. However, in certain models wherein the unstable self-excitation of wind variability penetrates back to the wind base, the stochastic, small-scale structure can become so dominant that it effectively disrupts any large-scale, CIR pattern.

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