scholarly journals Near-Surface Material Phases and Microstructure of Scandate Cathodes

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 636 ◽  
Author(s):  
Xiaotao Liu ◽  
Bernard Vancil ◽  
Matthew Beck ◽  
Thomas Balk
Keyword(s):  
Cathode Surface ◽  
State Of The Art ◽  
Synthesis Process ◽  
Surface Roughening ◽  
Near Surface ◽  
Oxide Phases ◽  
Complex Chemical Reactions ◽  
Scandate Cathode ◽  
Microscopy Techniques ◽  
Chemical Mixing

Scandate cathodes that were fabricated using the liquid-solid process and that exhibited excellent emission performance were characterized using complementary state-of-the-art electron microscopy techniques. Sub-micron BaAl2O4 particles were observed on the surfaces and edges of tungsten particles, as seen in cross-section samples extracted from the scandate cathode surface regions. Although several BaAl2O4 particles were observed to surround smaller Sc2O3 nanoparticles, no chemical mixing of the two oxides was detected, and in fact the distinct oxide phases were separately verified by chemical analysis and also by 3D elemental tomography. Nanobeam electron diffraction confirmed that the crystal structure throughout W grains is body-centered cubic, indicating that they are metallic W and did not experience noticeable changes, even near the grain surfaces, as a result of the numerous complex chemical reactions that occur during cathode impregnation and activation. 3D reconstruction further revealed that internal Sc/Sc2O3 particles tend to exhibit a degree of correlated arrangement within a given W particle, rather than being distributed uniformly throughout. Moreover, the formation of Sc/Sc2O3 particles within W grains may arise from W surface roughening that occurs during the liquid-solid synthesis process.

scholarly journals SHS robust modes to restore molybdenum by combustion wave in MoO3 – Al system

2020 ◽  
Vol 15 (4) ◽  
pp. 27-32
Author(s):  
Irina V. Milyukova ◽  
Marina P. Boronenko
Keyword(s):  
Spectral Analysis ◽  
High Temperature ◽  
Combustion Wave ◽  
Synthesis Process ◽  
Temperature Synthesis ◽  
Preliminary Heating ◽  
X Ray ◽  
Molybdenum Metal ◽  
High Temperature Synthesis ◽  
Oxide Phases

The work is devoted to the technology for the reduction of molybdenum from oxides by the method of self-propagating high-temperature synthesis in the MoO3 AI system with the addition of aluminum. The experiment was carried out in two modes: in a reactor at different pressures without preliminary heating and in a furnace in air until the initiation of the SH-synthesis process. Samples of molybdenum metal were obtained in different synthesis modes. X-ray phase and X-ray spectral analysis showed that molybdenum is the main phase in the synthesized samples. The presence of slag oxide phases Al2O3 and MoO2 was detected.

scholarly journals Deep-learning-based macro-pixel synthesis and lossless coding of light field images

2019 ◽  
Vol 8 ◽  
Author(s):  
Ionut Schiopu ◽  
Adrian Munteanu
Keyword(s):  
Light Field ◽  
State Of The Art ◽  
View Synthesis ◽  
Base Layer ◽  
Synthesis Process ◽  
Enhancement Layer ◽  
Novel Approach ◽  
Average Improvement ◽  
Lossless Coding ◽  
One Step

Abstract This paper proposes a novel approach for lossless coding of light field (LF) images based on a macro-pixel (MP) synthesis technique which synthesizes the entire LF image in one step. The reference views used in the synthesis process are selected based on four different view configurations and define the reference LF image. This image is stored as an array of reference MPs which collect one pixel from each reference view, being losslessly encoded as a base layer. A first contribution focuses on a novel network design for view synthesis which synthesizes the entire LF image as an array of synthesized MPs. A second contribution proposes a network model for coding which computes the MP prediction used for lossless encoding of the remaining views as an enhancement layer. Synthesis results show an average distortion of 29.82 dB based on four reference views and up to 36.19 dB based on 25 reference views. Compression results show an average improvement of 29.9% over the traditional lossless image codecs and 9.1% over the state-of-the-art.

AFM, LVHRSEM, and cross-sectional TEM of the near-surface morphology of diblock copolymers

1992 ◽  
Vol 50 (2) ◽  
pp. 1032-1033
Author(s):  
D. W. Schwark ◽  
D. L. Vezie ◽  
J. R. Reffner ◽  
E. L. Thomas ◽  
B. K. Annis ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Diblock Copolymers ◽  
Surface Composition ◽  
Low Voltage ◽  
Complete Characterization ◽  
Cross Sectional ◽  
Near Surface ◽  
Microscopy Technique ◽  
Self Assembling ◽  
Microscopy Techniques

Application of block copolymers as adhesives and biomedical devices requires an understanding of the surface composition and morphology of these materials. Microscopy techniques offer excellent depth and lateral resolution and therefore can provide direct microstructural and compositional surface data. Previous workers frequently used only a single microscopy technique to investigate the influence of an external surface constraint on the morphology. The implementation of several different microscopy techniques, each with its own strengths, affords a very complete characterization of the surface composition and morphology of self-assembling diblock copolymers.The investigation of solvent-cast and annealed thick (1 mm) films of two poly(styrene-b-butadiene) (SB) diblock copolymers, which usually self-assemble to form alternating poly(styrene) (PS) and poly (butadiene) (PB) lamellar microdomains, by three complementary microscopy techniques: cross-sectional transmission electron microscopy (CSTEM), low-voltage high-resolution scanning electron microscopy (LVHRSEM), and atomic force microscopy (AFM) is discussed. For CSTEM and LVHRSEM imaging, contrast between the PS and PB phases was enhanced by preferential staining of the PB phase with the vapors of a 4% aqueous osmium-tetroxide (OsO4) solution for 24 hours.

scholarly journals ERA5-Land: A state-of-the-art global reanalysis dataset for land applications

2021 ◽  
Author(s):  
Joaquín Muñoz-Sabater ◽  
Emanuel Dutra ◽  
Anna Agustí-Panareda ◽  
Clément Albergel ◽  
Gabriele Arduini ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Land Surface ◽  
Climate Models ◽  
Hydrological Cycle ◽  
State Of The Art ◽  
Weather Prediction ◽  
Added Value ◽  
Surface Model ◽  
Climate Data ◽  
Near Surface

Abstract. Framed within the Copernicus Climate Change Service of the European Commission, the European Centre for Medium-Range Weather Forecasts (ECMWF) is producing an enhanced global dataset for the land component of the 5th generation of European ReAnalysis (ERA5), hereafter named as ERA5-Land. Once completed, the period covered will span from 1950 to present, with continuous updates to support land monitoring applications. ERA5-Land describes the evolution of the water and energy cycles over land in a consistent manner over the production period, enabling the characterisation of trends and anomalies. This is achieved through global high resolution numerical integrations of the ECMWF land surface model driven by the downscaled meteorological forcing from the ERA5 climate reanalysis, including an elevation correction for the thermodynamic near-surface state. ERA5-Land shares with ERA5 most of the parametrizations that guarantees the use of the state-of-the-art land surface modeling applied to Numerical Weather Prediction (NWP) models. A main advantage of ERA5-Land compared to ERA5 and the older ERA-Interim is the horizontal resolution, which is enhanced globally to 9 km compared to 31 km (ERA5) or 80 km (ERA-Interim), whereas the temporal resolution is hourly as in ERA5. Evaluation against independent in situ observations and global model or satellite-based reference datasets shows the added value of ERA5-Land in the description of the hydrological cycle, in particular with enhanced soil moisture and lake description, and an overall better agreement of river discharge estimations with available observations. However, ERA5-Land snow depth fields present a mixed behaviour when compared to those of ERA5, depending on geographical location and altitude. The description of the energy cycle shows comparable results with ERA5. Nevertheless, ERA5-Land reduces the global averaged root mean square error of the skin temperature, taking as reference MODIS data, mainly due to the contribution of coastal points where spatial resolution is important. Since January 2020, the ERA5-Land period available extends from January 1981 to near present, with 2 to 3 months delay with respect to real-time. The segment prior to 1981 is in production, aiming to a release of the whole dataset in summer 2021. The high spatial and temporal resolution of ERA5-Land, its extended period, and the consistency of the fields produced makes it a valuable dataset to support hydrological studies, to initialise NWP and climate models, and to support diverse applications dealing with water resource, land and environmental management. The full ERA5-Land hourly and monthly averaged dataset presented in this paper are available through the Climate Data Store, https://doi.org/10.24381/cds.e2161bac and https://doi.org/10.24381/cds.68d2bb30, respectively.

scholarly journals Digital Twins: State-of-the-Art and Future Directions for Modeling and Simulation in Engineering Dynamics Applications

2020 ◽  
Vol 6 (3) ◽  
Author(s):  
D. J. Wagg ◽  
K. Worden ◽  
R. J. Barthorpe ◽  
P. Gardner
Keyword(s):  
Asset Management ◽  
State Of The Art ◽  
Industrial Applications ◽  
Transport Systems ◽  
Synthesis Process ◽  
Small Scale ◽  
Mathematical Framework ◽  
Digital Twin ◽  
Digital Twins

Abstract This paper presents a review of the state of the art for digital twins in the application domain of engineering dynamics. The focus on applications in dynamics is because: (i) they offer some of the most challenging aspects of creating an effective digital twin, and (ii) they are relevant to important industrial applications such as energy generation and transport systems. The history of the digital twin is discussed first, along with a review of the associated literature; the process of synthesizing a digital twin is then considered, including definition of the aims and objectives of the digital twin. An example of the asset management phase for a wind turbine is included in order to demonstrate how the synthesis process might be applied in practice. In order to illustrate modeling issues arising in the construction of a digital twin, a detailed case study is presented, based on a physical twin, which is a small-scale three-story structure. This case study shows the progression toward a digital twin highlighting key processes including system identification, data-augmented modeling, and verification and validation. Finally, a discussion of some open research problems and technological challenges is given, including workflow, joints, uncertainty management, and the quantification of trust. In a companion paper, as part of this special issue, a mathematical framework for digital twin applications is developed, and together the authors believe this represents a firm framework for developing digital twin applications in the area of engineering dynamics.

Application of Scanning Probe Microscopy Techniques with Electrical Modules in Via Related Defects

2012 ◽  
Author(s):  
Xiang-Dong Wang ◽  
N. David Theodore ◽  
Gil Garteiz ◽  
Paul Sanders
Keyword(s):  
Integrated Circuits ◽  
Scanning Probe Microscopy ◽  
State Of The Art ◽  
Scanning Probe ◽  
Force Microscopy ◽  
Large Size ◽  
Atomic Force ◽  
First Case ◽  
Conducting Path ◽  
Microscopy Techniques

Abstract Identifying defects in marginally failed vias has long been a challenge for failure analysis (FA) of state-of-the-art semiconductor integrated circuits. This paper presents two cases where a conventional FA approach is found to not be effective. The first case involves high resistance or marginally open vias. The second case involves early breakdown of large capacitors. The large size of the capacitor and the lack of ways to track electrical flow during diagnosis made it difficult to isolate the defect. The paper shows that conducting atomic force microscopy (C-AFM) and scanning capacitance microscopy (SCM) are effective techniques for isolation of via-related defects. The SCM technique could be applied to samples without a direct conducting path to the substrate, such as SOI samples. On the other hand, C-AFM allows current imaging as well as I-V characterization whenever a direct conductive path is available.

Scandate cathode surface characterization: Emission testing, elemental analysis and morphological evaluation

2019 ◽  
Vol 148 ◽  
pp. 188-200 ◽  
Author(s):  
Xiaotao Liu ◽  
Qunfei Zhou ◽  
Tyler L. Maxwell ◽  
Bernard K. Vancil ◽  
Matthew J. Beck ◽  
...  
Keyword(s):  
Elemental Analysis ◽  
Surface Characterization ◽  
Cathode Surface ◽  
Morphological Evaluation ◽  
Emission Testing ◽  
Scandate Cathode

The Effects of Particulate Contamination in Rolling Bearings—a State of the Art Review

1990 ◽  
Vol 204 (1) ◽  
pp. 29-36 ◽  
Author(s):  
R S Sayles ◽  
J C Hamer ◽  
E Ioannides
Keyword(s):  
Surface Defects ◽  
State Of The Art ◽  
Bearing Steel ◽  
Rolling Bearings ◽  
Near Surface ◽  
Particulate Contamination ◽  
Debris Particles ◽  
Rolling Contacts ◽  
The Subject ◽  
Fatigue Failures

The role played by particulate contamination in rolling contacts has formed the subject of much research in recent years. Bearing-steel quality has improved to a level where the long established sub-surface-inclusion based fatigue failures are being replaced by surface or near-surface initiated failures caused by surface defects resulting mainly from rolled-in debris particles. The paper reviews the reasons and mechanisms involved, and shows how particle material, size, concentration and hardness can all have effects on bearing reliability.

Plasticity in wheel–rail contact and its implications on vehicle–track interaction

2017 ◽  
Vol 231 (5) ◽  
pp. 558-569 ◽  
Author(s):  
K Six ◽  
A Meierhofer ◽  
G Trummer ◽  
C Bernsteiner ◽  
C Marte ◽  
...  
Keyword(s):  
Prediction Models ◽  
State Of The Art ◽  
Damage Model ◽  
Physical Processes ◽  
Surface Layers ◽  
Near Surface ◽  
High Importance ◽  
Wear Process ◽  
Railway Operation ◽  
Main Ideas

Vehicle–track interaction in railway operation is highly influenced by physical processes within the wheel–rail contact. Thus, accurate prediction models describing these processes are of high importance. Such models have to take into account the plasticity phenomena appropriately because such phenomena generally occur in the near-surface layers of wheels and rails in railway operation. Within the contact zone, two plasticity effects occur: ‘global’ plastification in the order of hundreds of microns up to millimetres due to the general loading situation and ‘tribological’ plastification in the order of microns due to surface effects (e.g. roughness) which is always accompanied by the wear process. State-of-the-art models do not take into account these effects sufficiently. The main ideas of the so-called overall wheel–rail contact and damage model taking into account the mentioned plasticity phenomena are presented together with typical results of the model.

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