scholarly journals A Near-Surface Microstructure Sensor System Used during TOGA COARE. Part I: Bow Measurements

1998 ◽  
Vol 15 (2) ◽  
pp. 563-578 ◽  
Author(s):  
Alexander Soloviev ◽  
Roger Lukas ◽  
Sharon DeCarlo ◽  
Jefrey Snyder ◽  
Anatoli Arjannikov ◽  
...  
Keyword(s):  
Sensor System ◽  
Surface Microstructure ◽  
Near Surface ◽  
Toga Coare

scholarly journals A Near-Surface Microstructure Sensor System Used during TOGA COARE. Part II: Turbulence Measurements

1999 ◽  
Vol 16 (11) ◽  
pp. 1598-1618 ◽  
Author(s):  
A. Soloviev ◽  
R. Lukas ◽  
P. Hacker ◽  
H. Schoeberlein ◽  
M. Baker ◽  
...  
Keyword(s):  
Sensor System ◽  
Surface Microstructure ◽  
Near Surface ◽  
Turbulence Measurements ◽  
Toga Coare

Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

Dissipation in the Bay of Bengal from a Seaglider

2021 ◽  
Author(s):  
Gillian Damerell ◽  
Peter Sheehan ◽  
Rob Hall ◽  
Adrian Matthews ◽  
Karen Heywood
Keyword(s):  
Time Series ◽  
Bay Of Bengal ◽  
Gradual Decrease ◽  
Vertical Flux ◽  
Sensor System ◽  
Atmospheric Forcing ◽  
Near Surface ◽  
Average Profile ◽  
Time Average

<p>In July 2016, a Seaglider equipped with a microstructure sensor system was deployed in the southern Bay of Bengal at 7° 54.0′ N, 89° 4.5′ E.  162 profiles (of which 146 were to 1000 m) of microstructure shear and temperature were collected as a time series at the same location.  Dissipation is calculated independently from both shear and temperature.  The time-average profile shows high dissipation (nearly 1×10<sup>-5</sup> W kg<sup>-1</sup>) near the surface, dropping rapidly over the uppermost 50 m to ~1×10<sup>-7</sup> W kg<sup>-1</sup>, followed by a more gradual decrease to ~5×10<sup>-10</sup> W kg<sup>-1</sup> at 300m.  A band of slightly higher dissipation around 500 m (~8×10<sup>-10</sup> W kg<sup>-1</sup>) could facilitate an increased vertical flux of nutrients, heat, salinity, etc at these depths.  From 600 to 1000 m dissipation remains roughly constant at ~1×10<sup>-10</sup> W kg<sup>-1</sup>.  Variability of the near surface dissipation in response to atmospheric forcing is also discussed.</p>

Laser Surface Processing for Tailoring of Properties by Optimization of Microstructure

2016 ◽  
pp. 121-171
Author(s):  
Jyotsna Dutta Majumdar ◽  
Andreas Weisheit ◽  
I. Manna
Keyword(s):  
Surface Region ◽  
Laser Surface ◽  
Processing Route ◽  
Surface Microstructure ◽  
High Power Laser ◽  
Surface Processing ◽  
Present Contribution ◽  
Near Surface ◽  
Rapid Processing ◽  
Equilibrium Microstructure

Laser surface processing involves modification of surface microstructure and/or composition of the near surface region of a component using a high power laser beam. The advantages of laser surface processing over conventional equilibrium surface processing include rapid processing rate, retention of non-equilibrium microstructure, alloying in liquid state and development of processed zone with superior properties as compared to the same developed by equilibrium processing route. Microstructure plays an important role to control the final properties of the tailored component. In the present contribution, with a brief introduction to laser, and its application, the microstructures developed under optimum conditions by different laser surface processing will be discussed with the corresponding improvement in properties. Finally, a brief review of the future scope of research in laser surface processing will be presented.

Near-Surface Microstructure on Twin-Roll Cast 8906 Aluminum Alloy

2015 ◽  
Vol 46 (6) ◽  
pp. 2688-2695 ◽  
Author(s):  
Junjie Wang ◽  
Xiaorong Zhou ◽  
George E. Thompson ◽  
John A. Hunter ◽  
Yudie Yuan
Keyword(s):  
Aluminum Alloy ◽  
Surface Microstructure ◽  
Near Surface ◽  
Twin Roll Cast ◽  
Twin Roll

scholarly journals On How Hot Towers Fuel the Hadley Cell: An Observational and Modeling Study of Line-Organized Convection in the Equatorial Trough from TOGA COARE

2009 ◽  
Vol 66 (9) ◽  
pp. 2730-2746 ◽  
Author(s):  
Alexandre O. Fierro ◽  
Joanne Simpson ◽  
Margaret A. LeMone ◽  
Jerry M. Straka ◽  
Bradley F. Smull
Keyword(s):  
Boundary Layer ◽  
Latent Heat ◽  
Hadley Cell ◽  
Cloud Base ◽  
Squall Line ◽  
Tropical Ocean ◽  
Near Surface ◽  
Radar Observations ◽  
Freezing Level ◽  
Toga Coare

Abstract An airflow trajectory analysis was carried out based on an idealized numerical simulation of the nocturnal 9 February 1993 equatorial oceanic squall line observed over the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) ship array. This simulation employed a nonhydrostatic numerical cloud model, which features a sophisticated 12-class bulk microphysics scheme. A second convective system that developed immediately south of the ship array a few hours later under similar environmental conditions was the subject of intensive airborne quad-Doppler radar observations, allowing observed airflow trajectories to be meaningfully compared to those from the model simulation. The results serve to refine the so-called hot tower hypothesis, which postulated the notion of undiluted ascent of boundary layer air to the high troposphere, which has for the first time been tested through coordinated comparisons with both model output and detailed observations. For parcels originating ahead (north) of the system near or below cloud base in the boundary layer (BL), the model showed that a majority (>62%) of these trajectories were able to surmount the 10-km level in their lifetime, with about 5% exceeding 14-km altitude, which was near the modeled cloud top (15.5 km). These trajectories revealed that during ascent, most air parcels first experienced a quick decrease of equivalent potential temperature (θe) below 5-km MSL as a result of entrainment of lower ambient θe air. Above the freezing level, ascending parcels experienced an increase in θe with height attributable to latent heat release from ice processes consistent with previous hypotheses. Analogous trajectories derived from the evolving observed airflow during the mature stage of the airborne radar–observed system identified far fewer (∼5%) near-BL parcels reaching heights above 10 km than shown by the corresponding simulation. This is attributed to both the idealized nature of the simulation and to the limitations inherent to the radar observations of near-surface convergence in the subcloud layer. This study shows that latent heat released above the freezing level can compensate for buoyancy reduction by mixing at lower levels, thus enabling air originating in the boundary layer to contribute to the maintenance of both local buoyancy and the large-scale Hadley cell despite acknowledged dilution by mixing along updraft trajectories. A tropical “hot tower” should thus be redefined as any deep convective cloud with a base in the boundary layer and reaching near the upper-tropospheric outflow layer.

Nanomechanical Properties of Aluminum 390-T6 Rough Surfaces Undergoing Tribological Testing

2004 ◽  
Vol 126 (3) ◽  
pp. 573-582 ◽  
Author(s):  
Shaun R. Pergande ◽  
Andreas A. Polycarpou ◽  
Thomas F. Conry
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Bulk Material ◽  
Normal Load ◽  
Effective Elastic Modulus ◽  
Surface Microstructure ◽  
Surface Material ◽  
Surface Layers ◽  
Near Surface ◽  
Nanomechanical Properties

The nanoindentation technique was used to quantify nano-scale changes in material properties (effective elastic modulus and hardness) of Al390-T6 samples that have undergone tribological testing under a protocol in a high-pressure tribometer where the applied normal load was step-wise increased until failure by scuffing occurred. The test was highly repeatable, so additional tests were run to three intermediate fractions of the total-time-to-scuffing-failure, which provided data on the progressive wear of the surfaces preparatory to reaching the scuffed condition. The samples were engineering surfaces with significant surface roughness, nonhomogeneous surface microstructure and unknown, nonuniform surface layers. This study demonstrated that nanomechanical techniques can be extended to characterize the material properties of rough engineering surfaces. For the samples subjected to tribological testing, the material at the surface, and to approximately 60 nm below the surface, exhibited significantly higher hardness than the bulk material. Also, progressive wear of the surfaces resulted in a corresponding weakening of the near-surface material below the surface to a depth of 60 nm, while the hardness of material below the 60 nm depth remained relatively unchanged. The hardness data for the scuffed samples showed a large amount of scatter in the data, indicating that the surface is not homogeneous and that the protective surface layer is removed, at least at some points on the surface.

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