A Novel Principle to Localize Scattered-wave Sensitivity Using Wave Interference and Its Adjoint

2021 ◽  
Author(s):  
Shohei Minato ◽  
Ranajit Ghose
Keyword(s):  
Scattered Wave ◽  
Boundary Integral ◽  
Propagation Path ◽  
Target Area ◽  
Seismic Velocities ◽  
Wave Interference ◽  
Wide Range ◽  
Key Factor ◽  
Resolution Imaging ◽  
Wave Sensitivity

Abstract When using scattered waves for high-resolution imaging of a medium, the sensitivity of these waves to the spatiotemporal distribution of heterogeneities is undoubtedly a key factor. The traditional principle behind using scattered waves to detect small changes suffers from an inherent limitation when other structures, not of interest, are present along the wave propagation path. We propose a novel principle that leads to enhanced localization of wave sensitivity, without having to know the intermediate structures. This new principle emerges from a boundary integral representation which utilizes wave interferences observed at multiple points. When tested on geophysical acoustic wave data, this new principle leads to much better sensitivity localization and detection of small changes in seismic velocities, which were otherwise impossible. Overcoming the insensitivity to a target area, it offers new possibilities for imaging and monitoring small changes in properties, which is critical in a wide range of disciplines and scales.

scholarly journals A novel principle to localize the sensitivity of waveform tomography using wave interferences at the observation boundary

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shohei Minato ◽  
Ranajit Ghose
Keyword(s):  
Boundary Integral ◽  
Propagation Path ◽  
Target Area ◽  
Seismic Velocities ◽  
Multiple Points ◽  
Wide Range ◽  
Resolution Imaging ◽  
Waveform Tomography ◽  
Sensitivity Changes ◽  
Boundary Integral Representation

AbstractWhen using waveform tomography to perform high-resolution imaging of a medium, it is vital to calculate the sensitivity in order to describe how well a model fits a given set of data and how the sensitivity changes with the spatial distribution of the heterogeneities. The traditional principle behind calculating the sensitivity—for detecting small changes—suffers from an inherent limitation in case other structures, not of interest, are present along the wave propagation path. We propose a novel principle that leads to enhanced localization of the sensitivity of the waveform tomography, without having to know the intermediate structures. This new principle emerges from a boundary integral representation which utilizes wave interferences observed at multiple points. When tested on geophysical acoustic wave data, this new principle leads to much better sensitivity localization and detection of small changes in seismic velocities, which were otherwise impossible. Overcoming the insensitivity to a target area, it offers new possibilities for imaging and monitoring small changes in properties, which is critical in a wide range of disciplines and scales.

scholarly journals Prediction of Wide Range Two-Dimensional Refractivity Using an IDW Interpolation Method from High-Altitude Refractivity Data of Multiple Meteorological Observatories

2021 ◽  
Vol 11 (4) ◽  
pp. 1431
Author(s):  
Sungsik Wang ◽  
Tae Heung Lim ◽  
Kyoungsoo Oh ◽  
Chulhun Seo ◽  
Hosung Choo
Keyword(s):  
High Altitude ◽  
Korean Peninsula ◽  
Interpolation Method ◽  
Atmospheric Condition ◽  
Propagation Path ◽  
Two Dimensional ◽  
Data Set ◽  
Wide Range ◽  
Atmospheric Data ◽  
Terrain Surface

This article proposes a method for the prediction of wide range two-dimensional refractivity for synthetic aperture radar (SAR) applications, using an inverse distance weighted (IDW) interpolation of high-altitude radio refractivity data from multiple meteorological observatories. The radio refractivity is extracted from an atmospheric data set of twenty meteorological observatories around the Korean Peninsula along a given altitude. Then, from the sparse refractive data, the two-dimensional regional radio refractivity of the entire Korean Peninsula is derived using the IDW interpolation, in consideration of the curvature of the Earth. The refractivities of the four seasons in 2019 are derived at the locations of seven meteorological observatories within the Korean Peninsula, using the refractivity data from the other nineteen observatories. The atmospheric refractivities on 15 February 2019 are then evaluated across the entire Korean Peninsula, using the atmospheric data collected from the twenty meteorological observatories. We found that the proposed IDW interpolation has the lowest average, the lowest average root-mean-square error (RMSE) of ∇M (gradient of M), and more continuous results than other methods. To compare the resulting IDW refractivity interpolation for airborne SAR applications, all the propagation path losses across Pohang and Heuksando are obtained using the standard atmospheric condition of ∇M = 118 and the observation-based interpolated atmospheric conditions on 15 February 2019. On the terrain surface ranging from 90 km to 190 km, the average path losses in the standard and derived conditions are 179.7 dB and 182.1 dB, respectively. Finally, based on the air-to-ground scenario in the SAR application, two-dimensional illuminated field intensities on the terrain surface are illustrated.

Therapy discontinuation in a primary care psychological service: why patients drop out

2020 ◽  
Vol 13 ◽  
Author(s):  
Aisan Ghaemian ◽  
Mahdi Ghomi ◽  
Miles Wrightman ◽  
Colm Ellis-Nee
Keyword(s):  
Drop Out ◽  
Treatment Withdrawal ◽  
List Type ◽  
Structured Interviews ◽  
Group Settings ◽  
Psychological Therapies ◽  
Psychological Service ◽  
Wide Range ◽  
Key Factor ◽  
Therapy Services

Abstract The present study aimed to explore patients’ experience with an Improving Access to Psychological Therapies (IAPT) service, and to investigate the reasons for discontinuing their treatment. A qualitative approach was adopted using thematic analysis of semi-structured interviews carried out with 818 patients attending for treatment in Talking Change from November 2015 to January 2019, retrospectively. The five main themes that emerged from the study were: ‘Felt better’, ‘Issues with group settings’, ‘Therapeutic alliance breakdown’, ‘Miscommunication’ and ‘Impracticalities’. The qualitative study uncovered a wide range of reasons for people who had dropped out from their treatment. The findings mainly emphasised general dissatisfaction and inconvenient appointments. However, improvement in symptoms of depression and anxiety was also identified as a key factor among patients who discontinued their treatment. This recovery is known as ‘progress withdrawal’ in which patients withdraw from treatment early due to good therapeutic progress. We present clinical and procedural implications arising from these themes. Key learning aims (1) To explore what can cause discontinuation of therapy. (2) To obtain the experience of people who have received treatment and dropped out from Talking Change Psychological Therapy services. (3) To explore whether people recovered as part of the treatment withdrawal and what may have helped towards that recovery.

scholarly journals DFT calculation and assignment of vibrational spectra of aryl and alkyl chlorophosphates

2014 ◽  
Vol 12 (2) ◽  
pp. 153-163
Author(s):  
Viktor Anishchenko ◽  
Vladimir Rybachenko ◽  
Konstantin Chotiy ◽  
Andrey Redko
Keyword(s):  
Vibrational Spectra ◽  
Basis Sets ◽  
Heavy Atoms ◽  
Wide Range ◽  
Complete Assignment ◽  
Key Factor ◽  
Polarization Functions ◽  
Experimental Values ◽  
Semi Empirical ◽  
Good Agreement

AbstractDFT calculations of vibrational spectra of chlorophosphates using wide range of basis sets and hybrid functionals were performed. Good agreement between calculated and experimental vibrational spectra was reached by the combination of non-empirical functional PBE0 with both middle and large basis sets. The frequencies of the stretching vibrations of the phosphate group calculated using semi-empirical functional B3LYP for all basis sets deviate significantly from the experimental values. The number of polarization functions on heavy atoms was shown to be a key factor for the calculation of vibrational frequencies of organophosphates. The importance of consideration of all the stable rotamers for a complete assignment of fundamental modes was shown.

High-resolution imaging: An approach by incorporating stationary-phase implementation into deabsorption prestack time migration

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. S317-S331 ◽  
Author(s):  
Jianfeng Zhang ◽  
Zhengwei Li ◽  
Linong Liu ◽  
Jin Wang ◽  
Jincheng Xu
Keyword(s):  
Stationary Phase ◽  
Fresnel Zone ◽  
Computational Cost ◽  
Computational Effort ◽  
Propagation Path ◽  
Time Migration ◽  
Resolution Imaging ◽  
Prestack Time Migration ◽  
Dip Angle ◽  
Absorption And Dispersion

We have improved the so-called deabsorption prestack time migration (PSTM) by introducing a dip-angle domain stationary-phase implementation. Deabsorption PSTM compensates absorption and dispersion via an actual wave propagation path using effective [Formula: see text] parameters that are obtained during migration. However, noises induced by the compensation degrade the resolution gained and deabsorption PSTM requires more computational effort than conventional PSTM. Our stationary-phase implementation improves deabsorption PSTM through the determination of an optimal migration aperture based on an estimate of the Fresnel zone. This significantly attenuates the noises and reduces the computational cost of 3D deabsorption PSTM. We have estimated the 2D Fresnel zone in terms of two dip angles through building a pair of 1D migrated dip-angle gathers using PSTM. Our stationary-phase QPSTM (deabsorption PSTM) was implemented as a two-stage process. First, we used conventional PSTM to obtain the Fresnel zones. Then, we performed deabsorption PSTM with the Fresnel-zone-based optimized migration aperture. We applied stationary-phase QPSTM to a 3D field data. Comparison with synthetic seismogram generated from well log data validates the resolution enhancements.

scholarly journals Momentum and Energy Transport by Gravity Waves in Stochastically Driven Stratified Flows. Part I: Radiation of Gravity Waves from a Shear Layer

2007 ◽  
Vol 64 (5) ◽  
pp. 1509-1529 ◽  
Author(s):  
Nikolaos A. Bakas ◽  
Petros J. Ioannou
Keyword(s):  
Shear Flow ◽  
Shear Layer ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Energy ◽  
Energy Transport ◽  
Wave Spectrum ◽  
Internal Gravity Waves ◽  
Wave Interference ◽  
Wide Range

Abstract In this paper, the emission of internal gravity waves from a local westerly shear layer is studied. Thermal and/or vorticity forcing of the shear layer with a wide range of frequencies and scales can lead to strong emission of gravity waves in the region exterior to the shear layer. The shear flow not only passively filters and refracts the emitted wave spectrum, but also actively participates in the gravity wave emission in conjunction with the distributed forcing. This interaction leads to enhanced radiated momentum fluxes but more importantly to enhanced gravity wave energy fluxes. This enhanced emission power can be traced to the nonnormal growth of the perturbations in the shear region, that is, to the transfer of the kinetic energy of the mean shear flow to the emitted gravity waves. The emitted wave energy flux increases with shear and can become as large as 30 times greater than the corresponding flux emitted in the absence of a localized shear region. Waves that have horizontal wavelengths larger than the depth of the shear layer radiate easterly momentum away, whereas the shorter waves are trapped in the shear region and deposit their momentum at their critical levels. The observed spectrum, as well as the physical mechanisms influencing the spectrum such as wave interference and Doppler shifting effects, is discussed. While for large Richardson numbers there is equipartition of momentum among a wide range of frequencies, most of the energy is found to be carried by waves having vertical wavelengths in a narrow band around the value of twice the depth of the region. It is shown that the waves that are emitted from the shear region have vertical wavelengths of the size of the shear region.

scholarly journals Testing repeatability, measurement error and species differentiation when using geometric morphometrics on complex shapes: a case study of Patagonian lizards of the genus Liolaemus (Squamata: Liolaemini)

2020 ◽  
Vol 130 (4) ◽  
pp. 800-812 ◽  
Author(s):  
Juan Vrdoljak ◽  
Kevin Imanol Sanchez ◽  
Roberto Arreola-Ramos ◽  
Emilce Guadalupe Diaz Huesa ◽  
Alejandro Villagra ◽  
...  
Keyword(s):  
Measurement Error ◽  
Geometric Morphometrics ◽  
Evolutionary Biology ◽  
Species Differentiation ◽  
Geometric Morphometric ◽  
Operator Error ◽  
Wide Range ◽  
Complex Shapes ◽  
Key Factor ◽  
Sources Of Variation

Abstract The repeatability of findings is the key factor behind scientific reliability, and the failure to reproduce scientific findings has been termed the ‘replication crisis’. Geometric morphometrics is an established tool in evolutionary biology. However, different operators (and/or different methods) could act as large sources of variation in the data obtained. Here, we investigated inter-operator error in geometric morphometric protocols on complex shapes of Liolaemus lizards, as well as measurement error in three taxa varying in their difficulty of digitalization. We also examined the potential for these protocols to discriminate among complex shapes in closely related species. We found a wide range of inter-operator error, contributing between 19.5% and 60% to the total variation. Moreover, measurement error increased with the complexity of the quantified shape. All protocols were able to discriminate between species, but the use of more landmarks did not imply better performance. We present evidence that complex shapes reduce repeatability, highlighting the need to explore different sources of variation that could lead to such low repeatability. Lastly, we suggest some recommendations to improve the repeatability and reliability of geometric morphometrics results.

scholarly journals Trust as a Key Factor in Shaping the Social Business Model of Water Supply Companies

2019 ◽  
Vol 11 (20) ◽  
pp. 5805 ◽  
Author(s):  
Jabłoński ◽  
Jabłoński
Keyword(s):  
Water Supply ◽  
Business Model ◽  
Business Models ◽  
Scientific Research ◽  
Social Enterprises ◽  
Social Business ◽  
The Social ◽  
Wide Range ◽  
Key Factor ◽  
Water Supply Company

The current principles of doing business differ radically from those that were applied a few years ago. Global economic crises have shown that business must have a more social character. This gave rise to the creation of management solutions that would guarantee the satisfaction of a wide range of corporate stakeholders. In this context, ideas based on social potential began to emerge. As a consequence, the concept of social business models was born, accompanied by an attempt to search for the best business models possible in order to build the appropriate configuration of their components. According to the authors, an attribute of trust may be such a component based on which effective social business models can be built. As water supply companies are social enterprises, they have become the object of scientific research in this case. The purpose of the article is to determine the position of trust in the construction and application of social business models of water supply companies. The scope of the article includes scientific research into water supply companies in the most industrial region of Poland, Upper Silesia, with the most extensive and dense water supply network in the country. In this article, the AHP (analytic hierarchy process) method was used to conduct research. The aim of the analysis was focusing on the issue of trust as a key factor in shaping the social business model of the company. In the questionnaires, respondents were asked to answer questions on the following issues: trust-based organizational behavior at the company; trust-based social capital at the company; trust-based relationships at the company; trust-based processes and activities at the company; trust-based risk at the company; and the trust-based business model at the company. The adopted logic of the scientific argument conducted indicates that trust and its place and role in the social business model of a water supply company have a significant impact on the social and economic performance of the water supply company, and as a consequence, on increased social responsibility towards stakeholders as well. Trust even stabilizes the organization and its business model; it is also a value catalyst and neutralizes the potentially negative impact of the organization on other entities gathered around it. Trust as a stabilizer can also affect the consistency and scalability of the social business model of a water supply company.

scholarly journals Improving the understanding of flood risk in the Alsatian region by knowledge capitalization: the ORRION participative observatory

2018 ◽  
Author(s):  
Florie Giacona ◽  
Brice Martin ◽  
Benjamin Furst ◽  
Rüdiger Glaser ◽  
Nicolas Eckert ◽  
...  
Keyword(s):  
Flood Risk ◽  
Flood Hazard ◽  
Common Knowledge ◽  
Synoptic Situation ◽  
Target Area ◽  
15Th Century ◽  
Key Factor ◽  
Data Content ◽  
Rich Data ◽  
Knowledge Capitalization

Abstract. Despite the strong societal impact of natural hazards, their documentation remains incomplete, with only a few inventories exceeding the past two centuries. Surprisingly enough, this also applies to Europe, a densely populated territory, and to floods, which along with storms is the most common and damage-causing natural hazard in this area. In addition, existing inventories have often been compiled by scientists and technicians and are used for risk management in a top-down manner, although the participation of all parties concerned has been recognized as a key factor for disaster reduction. To address this double paradox, the present article presents the regional flood risk observatory ORRION for the Alsatian region, northeastern France, and its very rich data content. Stemming from two successive interdisciplinary and transnational French-German research projects, ORRION was designed as a participative online platform where information is shared between individuals, stakeholders, engineers, and scientists. This original approach aims at maximizing knowledge capitalization and contributes to building a common knowledge base for flood risk. ORRION is organized by events including all river floods that have likely arisen from a single synoptic situation. For each event, it documents information sources, date of occurrence, causes, and consequences in terms of damage and affected river basins and municipalities. ORRION contributed toward renewing our knowledge of flood hazard and risk in the target area. Notably, here, long chronicles of floods are derived for 13 rivers, the Rhine and most of its main Alsatian tributaries, and for all Alsatian municipalities, most of them since the end of the 15th century, but over more than one millennium for the Rhine. Their main characteristics according to various typologies (seasonality, causes, severity, etc.) are analyzed. Major developments over the study period related to sources, land use, and/or climate change are identified. The advantages and limitations of the approach are discussed and the potential to expand both data exploitation and the building of common flood risk knowledge are listed.

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