scholarly journals Электрохимическая эмиссия при деформировании и разрушении алюминий-магниевого сплава в водной среде

2020 ◽  
Vol 90 (1) ◽  
pp. 85
Author(s):  
А.А. Шибков ◽  
М.Ф. Гасанов ◽  
А.Е. Золотов ◽  
М.А. Желтов ◽  
А.А. Денисов ◽  
...  
Keyword(s):  
Aqueous Medium ◽  
High Speed ◽  
Temporal Structure ◽  
Deformation Bands ◽  
Discrete Signals ◽  
Localization Of Plastic Deformation ◽  
Temporal Structures ◽  
In Situ Methods ◽  
Spatio Temporal

Spatio-temporal structures of Portevin-Le Chatelier deformation bands at the pre-failure stage, necking and destruction of an aluminum-magnesium alloy, deformable in an aqueous medium, were investigated by a complex of in situ methods, including high-speed video of the surface and an electrochemical emission method. The latter is based on measuring and analyzing jumps in the electrode potential of a deformable metal under the conditions of the manifestation of intermittent deformation. It is established that discrete signals of electrochemical emission in the frequency band of 10 Hz - 10 kHz contain information on the number of deformation bands, the moments of nucleation and stages of their growth, the statistical temporal structure of the bands, etc. A characteristic series of signals at the pre-failure stage is revealed − an electrochemical precursor neck formation and specimen fracture. The connection between the generation of electrochemical emission signals and the localization of plastic deformation and the destruction of an oxide film on an aluminum alloy surface in contact with an aqueous medium is discussed.

High-Speed In Situ Study of the Correlation between the Deformation Bands Formation and Acoustic Response in Al–Mg Alloy

2020 ◽  
Vol 65 (4) ◽  
pp. 546-553 ◽  
Author(s):  
A. A. Shibkov ◽  
M. F. Gasanov ◽  
A. E. Zolotov ◽  
A. A. Denisov ◽  
S. S. Kochegarov ◽  
...  
Keyword(s):  
High Speed ◽  
Mg Alloy ◽  
Acoustic Response ◽  
Deformation Bands ◽  
In Situ Study

An atomic-resolution microscope study of Al contracts on GaAs

1986 ◽  
Vol 44 ◽  
pp. 726-727
Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn
Keyword(s):  
High Speed ◽  
Schottky Contacts ◽  
Detailed Knowledge ◽  
The Past ◽  
Semiconductor Interfaces ◽  
Deposited Metal ◽  
Microwave Applications ◽  
Free Interfaces ◽  
Potential Use

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions

LIGHTER-THAN-AIR (LTA) UNMANNED AERIAL SYSTEM (UAS) CARRIER CONCEPT FOR SURVAILLANCE AND DISASTER MANAGEMENT

2019 ◽  
Vol 3 ◽  
pp. 1255
Author(s):  
Ahmad Salahuddin Mohd Harithuddin ◽  
Mohd Fazri Sedan ◽  
Syaril Azrad Md Ali ◽  
Shattri Mansor ◽  
Hamid Reza Jifroudi ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Disaster Management ◽  
Unmanned Aerial Systems ◽  
Unmanned Aerial System ◽  
Border Control ◽  
Aerial Vehicles ◽  
Operational Safety ◽  
In Situ Methods ◽  
Aerial Systems

Unmanned aerial systems (UAS) has many advantages in the fields of SURVAILLANCE and disaster management compared to space-borne observation, manned missions and in situ methods. The reasons include cost effectiveness, operational safety, and mission efficiency. This has in turn underlined the importance of UAS technology and highlighted a growing need in a more robust and efficient unmanned aerial vehicles to serve specific needs in SURVAILLANCE and disaster management. This paper first gives an overview on the framework for SURVAILLANCE particularly in applications of border control and disaster management and lists several phases of SURVAILLANCE and service descriptions. Based on this overview and SURVAILLANCE phases descriptions, we show the areas and services in which UAS can have significant advantage over traditional methods.

scholarly journals Spatially Resolved Experimental Modal Analysis on High-Speed Composite Rotors Using a Non-Contact, Non-Rotating Sensor

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4705
Author(s):  
Julian Lich ◽  
Tino Wollmann ◽  
Angelos Filippatos ◽  
Maik Gude ◽  
Juergen Czarske ◽  
...  
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Fiber Reinforced ◽  
Structural Dynamic ◽  
Spatially Resolved ◽  
Glass Fiber Reinforced ◽  
Vibration Responses ◽  
And Performance

Due to their lightweight properties, fiber-reinforced composites are well suited for large and fast rotating structures, such as fan blades in turbomachines. To investigate rotor safety and performance, in situ measurements of the structural dynamic behaviour must be performed during rotating conditions. An approach to measuring spatially resolved vibration responses of a rotating structure with a non-contact, non-rotating sensor is investigated here. The resulting spectra can be assigned to specific locations on the structure and have similar properties to the spectra measured with co-rotating sensors, such as strain gauges. The sampling frequency is increased by performing consecutive measurements with a constant excitation function and varying time delays. The method allows for a paradigm shift to unambiguous identification of natural frequencies and mode shapes with arbitrary rotor shapes and excitation functions without the need for co-rotating sensors. Deflection measurements on a glass fiber-reinforced polymer disk were performed with a diffraction grating-based sensor system at 40 measurement points with an uncertainty below 15 μrad and a commercial triangulation sensor at 200 measurement points at surface speeds up to 300 m/s. A rotation-induced increase of two natural frequencies was measured, and their mode shapes were derived at the corresponding rotational speeds. A strain gauge was used for validation.

Enhanced Grain Refinement of W18Cr4V High‐Speed Steel using in situ TiN‐Nb‐Cr@Graphene/Fe Nanocomposite Inoculant

2021 ◽  
Author(s):  
Lina Bai ◽  
Chunxiang Cui ◽  
Jianjun Zhang ◽  
Lichen Zhao ◽  
Guixing Zheng ◽  
...  
Keyword(s):  
Grain Refinement ◽  
High Speed ◽  
High Speed Steel

scholarly journals Influence of Hydrogeochemistry on Tunnel Drainage in Evaporitic Formations: El Regajal Tunnel Case Study (Aranjuez, Spain)

2021 ◽  
Vol 13 (3) ◽  
pp. 1505
Author(s):  
Ignacio Menéndez Pidal ◽  
Jose Antonio Mancebo Piqueras ◽  
Eugenio Sanz Pérez ◽  
Clemente Sáenz Sanz
Keyword(s):  
High Speed ◽  
Civil Engineering ◽  
Saturation Index ◽  
The Subject ◽  
Under Construction ◽  
Underground Flow ◽  
Very High ◽  
Over Time

Many of the large number of underground works constructed or under construction in recent years are in unfavorable terrains facing unusual situations and construction conditions. This is the case of the subject under study in this paper: a tunnel excavated in evaporitic rocks that experienced significant karstification problems very quickly over time. As a result of this situation, the causes that may underlie this rapid karstification are investigated and a novel methodology is presented in civil engineering where the use of saturation indices for the different mineral specimens present has been crucial. The drainage of the rock massif of El Regajal (Madrid-Toledo, Spain, in the Madrid-Valencia high-speed train line) was studied and permitted the in-situ study of the hydrogeochemical evolution of water flow in the Miocene evaporitic materials of the Tajo Basin as a full-scale testing laboratory, that are conforms as a whole, a single aquifer. The work provides a novel methodology based on the calculation of activities through the hydrogeochemical study of water samples in different piezometers, estimating the saturation index of different saline materials and the dissolution capacity of the brine, which is surprisingly very high despite the high electrical conductivity. The circulating brine appears unsaturated with respect to thenardite, mirabilite, epsomite, glauberite, and halite. The alteration of the underground flow and the consequent renewal of the water of the aquifer by the infiltration water of rain and irrigation is the cause of the hydrogeochemical imbalance and the modification of the characteristics of the massif. These modifications include very important loss of material by dissolution, altering the resistance of the terrain and the increase of the porosity. Simultaneously, different expansive and recrystallization processes that decrease the porosity of the massif were identified in the present work. The hydrogeochemical study allows the evolution of these phenomena to be followed over time, and this, in turn, may facilitate the implementation of preventive works in civil engineering.

scholarly journals Controlling the spatio-temporal dose distribution during STEM imaging by subsampled acquisition: In-situ observations of kinetic processes in liquids

2019 ◽  
Vol 115 (6) ◽  
pp. 063102 ◽  
Author(s):  
B. L. Mehdi ◽  
A. Stevens ◽  
L. Kovarik ◽  
N. Jiang ◽  
H. Mehta ◽  
...  
Keyword(s):  
Dose Distribution ◽  
In Situ Observations ◽  
Kinetic Processes ◽  
Spatio Temporal
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