scholarly journals Interferometric hydrofracture microseism localization using neighboring fracture

Geophysics ◽  
2011 ◽  
Vol 76 (6) ◽  
pp. WC27-WC36 ◽  
Author(s):  
Oleg V. Poliannikov ◽  
Alison E. Malcolm ◽  
Hugues Djikpesse ◽  
Michael Prange
Keyword(s):  
Signal To Noise Ratio ◽  
Common Source ◽  
Square Root ◽  
Multiple Sources ◽  
Multiple Fractures ◽  
Additional Information ◽  
Monitoring Well ◽  
Receiver Array ◽  
Second Fracture ◽  
Available Information

Hydraulic fracturing is the process of injecting high-pressure fluids into a reservoir to induce fractures and thus improve reservoir productivity. Microseismic event localization is used to locate created fractures. Traditionally, events are localized individually. Available information about events already localized is not used to help estimate other source locations. Traditional localization methods yield an uncertainty that is inversely proportional to the square root of the number of receivers. However, in applications where multiple fractures are created, multiple sources in a reference fracture may provide redundant information about unknown events in subsequent fractures that can boost the signal-to-noise ratio, improving estimates of the event positions. We used sources in fractures closer to the monitoring well to help localize events further away. It is known through seismic interferometry that with a 2D array of receivers, the traveltime between two sources may be recovered from a crosscorrelogram of two common source gathers. This allowed an event in the second fracture to be localized relative to an event in the reference fracture. A difficulty became evident when receivers are located in a single monitoring well. When the receiver array is 1D, classical interferometry cannot be directly employed because the problem becomes underdetermined. In our approach, interferometry was used to partially redatum microseismic events from the second fracture onto the reference fracture so that they can be used as virtual receivers, providing additional information complementary to that provided by the physical receivers. Our error analysis showed that, in addition to the gain obtained by having multiple physical receivers, the location uncertainty is inversely proportional to the square root of the number of sources in the reference fracture. Because the number of microseism sources is usually high, the proposed method will usually result in more accurate location estimates as compared with the traditional methods.

scholarly journals The use of hyperpolarised 13C-MRI in clinical body imaging to probe cancer metabolism

2021 ◽  
Author(s):  
Ramona Woitek ◽  
Ferdia A. Gallagher
Keyword(s):  
Cancer Metabolism ◽  
Signal To Noise Ratio ◽  
Response Assessment ◽  
Early Response ◽  
Multiparametric Mri ◽  
Metabolic Reprogramming ◽  
Response To Treatment ◽  
Additional Information ◽  
Positron Emission ◽  
Breast And Prostate Cancer

AbstractMetabolic reprogramming is one of the hallmarks of cancer and includes the Warburg effect, which is exhibited by many tumours. This can be exploited by positron emission tomography (PET) as part of routine clinical cancer imaging. However, an emerging and alternative method to detect altered metabolism is carbon-13 magnetic resonance imaging (MRI) following injection of hyperpolarised [1-13C]pyruvate. The technique increases the signal-to-noise ratio for the detection of hyperpolarised 13C-labelled metabolites by several orders of magnitude and facilitates the dynamic, noninvasive imaging of the exchange of 13C-pyruvate to 13C-lactate over time. The method has produced promising preclinical results in the area of oncology and is currently being explored in human imaging studies. The first translational studies have demonstrated the safety and feasibility of the technique in patients with prostate, renal, breast and pancreatic cancer, as well as revealing a successful response to treatment in breast and prostate cancer patients at an earlier stage than multiparametric MRI. This review will focus on the strengths of the technique and its applications in the area of oncological body MRI including noninvasive characterisation of disease aggressiveness, mapping of tumour heterogeneity, and early response assessment. A comparison of hyperpolarised 13C-MRI with state-of-the-art multiparametric MRI is likely to reveal the unique additional information and applications offered by the technique.

ARESIBO HORIZON 2020 EUROPEAN RESEARCH PROJECT – ENRICHED SITUATION AWARENESS FOR BORDER SURVEILLANCE

2021 ◽  
Vol 17 (1) ◽  
pp. 247-255
Author(s):  
Konstantinos CHARISI ◽  
Andreas TSIGOPOULOS ◽  
Spyridon KINTZIOS ◽  
Vassilis PAPATAXIARHIS
Keyword(s):  
Augmented Reality ◽  
Situation Awareness ◽  
User Interfaces ◽  
Border Security ◽  
Multiple Sources ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
Current State ◽  
Available Information ◽  
User Friendly

Abstract. The paper aims to introduce the ARESIBO project to a greater but targeted audience and outline its main scope and achievements. ARESIBO stands for “Augmented Reality Enriched Situation awareness for Border security”. In the recent years, border security has become one of the highest political priorities in EU and needs the support of every Member State. ARESIBO project is developed under HORIZON 2020 EC Research and Innovation program and it is the joint effort of 20 participant entities from 11 countries. Scientific excellence and technological innovation are top priorities as ARESIBO enhances the current state-of-the-art through technological breakthroughs in Mobile Augmented Reality and Wearables, Robust and Secure Telecommunications, Robots swarming technique and Planning of Context-Aware Autonomous Missions, and Artificial Intelligence (AI), in order to implement user-friendly tools for border and coast guards. The system aims to improve the cognitive capabilities and the perception of border guards through intuitive user interfaces that will help them acquire an improved situation awareness by filtering the huge amount of available information from multiple sources. Ultimately, it will help them respond faster and more effectively when a critical situation occurs.

scholarly journals SDSS-IV MaNGA: the spectroscopic discovery of strongly lensed galaxies

2018 ◽  
Vol 477 (1) ◽  
pp. 195-209 ◽  
Author(s):  
Michael S Talbot ◽  
Joel R Brownstein ◽  
Adam S Bolton ◽  
Kevin Bundy ◽  
Brett H Andrews ◽  
...  
Keyword(s):  
Emission Line ◽  
Narrow Band ◽  
Signal To Noise Ratio ◽  
Gravitational Lens ◽  
Emission Lines ◽  
High Signal ◽  
Common Source ◽  
Narrow Band Image ◽  
Background Emission ◽  
Field Unit

Abstract We present a catalogue of 38 spectroscopically detected strong galaxy–galaxy gravitational lens candidates identified in the Sloan Digital Sky Survey IV (SDSS-IV). We were able to simulate narrow-band images for eight of them demonstrating evidence of multiple images. Two of our systems are compound lens candidates, each with two background source-planes. One of these compound systems shows clear lensing features in the narrow-band image. Our sample is based on 2812 galaxies observed by the Mapping Nearby Galaxies at APO (MaNGA) integral field unit (IFU). This Spectroscopic Identification of Lensing Objects (SILO) survey extends the methodology of the Sloan Lens ACS Survey (SLACS) and BOSS Emission-Line Survey (BELLS) to lower redshift and multiple IFU spectra. We searched ∼1.5 million spectra, of which 3065 contained multiple high signal-to-noise ratio background emission-lines or a resolved [O ii] doublet, that are included in this catalogue. Upon manual inspection, we discovered regions with multiple spectra containing background emission-lines at the same redshift, providing evidence of a common source-plane geometry which was not possible in previous SLACS and BELLS discovery programs. We estimate more than half of our candidates have an Einstein radius ≳ 1.7 arcsec, which is significantly greater than seen in SLACS and BELLS. These larger Einstein radii produce more extended images of the background galaxy increasing the probability that a background emission-line will enter one of the IFU spectroscopic fibres, making detection more likely.

scholarly journals Steering Acoustic Intensity Estimator Using a Single Acoustic Vector Hydrophone

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Guang Pu Zhang ◽  
Ce Zheng ◽  
Wang Sheng Lin
Keyword(s):  
Signal To Noise Ratio ◽  
Azimuth Angle ◽  
Acoustic Energy ◽  
Multiple Sources ◽  
Acoustic Intensity ◽  
Angle Estimation ◽  
Sea Trial ◽  
Vector Hydrophone ◽  
Global Positioning ◽  
Intensity Estimator

Azimuth angle estimation using a single vector hydrophone is a well-known problem in underwater acoustics. In the presence of multiple sources, a conventional complex acoustic intensity estimator (CAIE) cannot distinguish the azimuth angle of each source. In this paper, we propose a steering acoustic intensity estimator (SAIE) for azimuth angle estimation in the presence of interference. The azimuth angle of the interference is known in advance from the global positioning system (GPS) and compass data. By constructing the steering acoustic energy fluxes in the x and y channels of the acoustic vector hydrophone, the azimuth angle of interest can be obtained when the steering azimuth angle is directed toward the interference. Simulation results show that the SAIE outperforms the CAIE and is insensitive to the signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR). A sea trial is presented that verifies the validity of the proposed method.

Imaging passive seismic data

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. SI177-SI187 ◽  
Author(s):  
Brad Artman
Keyword(s):  
Water Table ◽  
Seismic Data ◽  
Survey Design ◽  
Signal To Noise Ratio ◽  
Multiple Sources ◽  
Depth Migration ◽  
Reflection Seismic ◽  
Ambient Sound ◽  
Passive Seismic ◽  
Passive Data

Imaging passive seismic data is the process of synthesizing the wealth of subsurface information available from reflection seismic experiments by recording ambient sound using an array of geophones distributed at the surface. Crosscorrelating the traces of such a passive experiment can synthesize data that are identical to actively collected reflection seismic data. With a correlation-based imaging condition, wave-equation shot-profile depth migration can use raw transmission wavefields as input for producing a subsurface image. Migration is even more important for passively acquired data than for active data because with passive data, the source wavefields are likely to be weak compared with background and instrument noise — a condition that leads to a low signal-to-noise ratio. Fourier analysis of correlating long field records shows that aliasing of the wavefields from distinct shots is unavoidable. Although this reduces the order of computations for correlation by the length of the original trace, the aliasing produces an output volume that may not be substantially more useful than the raw data because of the introduction of crosstalk between multiple sources. Direct migration of raw field data still can produce an accurate image, even when the transmission wavefields from individual sources are not separated. To illustrate direct migration, I use images from a shallow passive seismic investigation targeting a buried hollow pipe and the water-table reflection. These images show a strong anomaly at the 1-m depth of the pipe and faint events that could be the water table at a depth of around [Formula: see text]. The images are not clear enough to be irrefutable. I identify deficiencies in survey design and execution to aid future efforts.

Adding Information May Increase Overconfidence in Accuracy of Knowledge Retrieval

2011 ◽  
Vol 108 (2) ◽  
pp. 379-392 ◽  
Author(s):  
Dida Fleisig
Keyword(s):  
Group Performance ◽  
Control Group ◽  
Misleading Information ◽  
Intact Group ◽  
Group Design ◽  
Additional Information ◽  
Choice Processes ◽  
Correct Information ◽  
Information Group ◽  
Available Information

Feelings of retrospective confidence concerning the accuracy of a chosen answer might rely, among other things, on the amount of available information, regardless of its correctness. 43 participants, 26 women and 17 men ( M age = 23.4 yr., SD = 3.5) in an intact group design, answered nine easy and nine difficult binary forced-choice questions and rated their confidence regarding the correctness of their choices. Participants were randomly assigned to one of three groups, differing in the additional information provided regarding the questions: a control group provided with no additional information, a correct information group, and a misleading information group. Performance was worst in the misleading information group, yet no difference in confidence was found between the correct and misleading information groups. The findings were interpreted as supporting the hypothesis that feelings of confidence partly reflect peripheral factors, indirectly related to choice processes.

scholarly journals Scholar Mirrors: Integrating evidence of impact from multiple sources into one platform to expedite researcher evaluation

2018 ◽  
Author(s):  
Alberto Martín-Martín ◽  
Enrique Orduna-Malea ◽  
Emilio Delgado López-Cózar
Keyword(s):  
Web Application ◽  
Scientific Discipline ◽  
Google Scholar ◽  
Multiple Sources ◽  
Additional Information ◽  
Level Data ◽  
Future Challenges ◽  
Document Collection ◽  
Evidence Of Impact

This paper describes the creation of “Scholar Mirrors”, a prototype web application that aims to provide a quick but accurate representation of the situation of a scientific discipline by integrating data from multiple online platforms. We chose the discipline of Bibliometrics / Scientometrics as a case study. After carrying out a series of keywords searches in Google Scholar Citations (GSC) and Google Scholar (GS), 813 relevant researchers were identified. Researchers were further classified as core (those who work mainly on Scientometrics) or related (those who work in other disciplines, with occasional incursions into Scientometrics). Additional information about these researchers was collected from other platforms (ResearcherID, ResearchGate, Mendeley, and Twitter). Up to 28 author-level indicators were collected about each researcher, as well as data about up to 100 of the most cited documents displayed in their GSC profile. The document-level data from all GSC profiles, as well as the data extracted from the keyword searchers in GS, was aggregated to create a list of the top 1000 most cited documents in the discipline. This document collection was further processed to generate a list of the most influential journals and publishers in the discipline. The results are accessible from the “Scholar Mirrors” website, which presents the results in four sections: authors, documents, journals, and book publishers. Lastly, the paper presents the main features of the web application, and the main limitations and future challenges of the product.

scholarly journals The municipality as a source of information?

2014 ◽  
Vol 3 (3) ◽  
pp. 41
Author(s):  
Roman Vavrek ◽  
Ivana Kravčáková Vozárová ◽  
Martina Cehlárová ◽  
Ivana Ondrijová
Keyword(s):  
Local Government ◽  
Free Access ◽  
Access To Information ◽  
Multiple Sources ◽  
Basic Set ◽  
Available Information ◽  
Source Of Information

The municipality as an entity of the local government and disposes defined rights and obligations, which are governed by the special regulations. In accordance with Act no. 211/2000 Coll. on free access to information, the municipality is mandatory publish and make available information that this Act also more specify. This paper focuses on availability of information from websites or other available sources. The basic set was represented by 91 municipalities of Prešov district, in which were surveyed a total of 75 data (6 identification and 69 financial). Within the implemented questioning, we can conclude especially the availability of identification data, for which there are multiple sources (eg. number of inhabitants). Overall, however, the municipalities did not provide the requested information, when up to 27 municipalities did not provide more than 5 data (including 3 identification). One of the outcomes is also a proving of small correlation between the volume of data obtained from the municipality and the number of its inhabitants, respectively the distance from the district town.

Assessing Information Assessments

2016 ◽  
Author(s):  
Arthur Lupia
Keyword(s):  
Political Information ◽  
Common Source ◽  
Specific Information ◽  
Information Effects ◽  
Interviewer Ratings ◽  
Available Information ◽  
The Relationship ◽  
Very High ◽  
Over Time ◽  
Variable Quality

While many analysts use PK scales to make claims about what people know and why it matters, others use subjective interviewer assessments. The ANES is a common source of these assessments. The ANES asks its interviewers to offer “a five-level summary evaluation of each respondent’s level of information level.” Interviewers rate each respondent as “very high,” “high,” “average,” “fairly low,” or “very low.” Data from these assessments appear in widely cited academic articles on political ignorance. In one such article, Bartels (1996: 203) argues that this variable’s use is preferable to PK scales. He claims that interviewer assessments are . . . no less (and sometimes more) strongly related than factual information scales are to relevant criterion values such as political interest, education, registration, and turnout (Zaller 1985: 4). Given the added difficulty of making comparisons from one election year to another using scales based on rather different sets of available information items of variable quality, the simpler interviewer ratings seem preferable for my purposes here. . . . Other scholars have augmented the case for using interviewer assessments in attempts to understand the relationship between knowledge and other factors. As Claassen and Highton (2006: 415) write: . . . To measure political information, we rely on NES interviewer ratings of respondents’ levels of political information. This indicator has two primary virtues. First, it is present in each of the surveys we analyze providing a consistent measure across survey years. Second, it has proven to be a valid measure. Bartels used it to provide important insights into public opinion toward … information effects in presidential voting (Bartels, 1996). Given our focus on changing information effects over time, we share the view that because of the “added difficulty of making comparisons from one election year to another using scales based on rather different sets of available information items of variable quality, the simpler interviewer ratings seem preferable.” . . . In a footnote (2006: 415n), they continue the argument: . . . For the purposes of this paper, we also prefer the interviewer rating to measures of policy specific information. . . .

Multichannel Alignment of S Waves

2021 ◽  
Author(s):  
Michael Bostock ◽  
Alexandre Plourde ◽  
Doriane Drolet ◽  
Geena Littel
Keyword(s):  
Effective Means ◽  
Principal Component ◽  
Singular Value ◽  
Body Waves ◽  
Common Source ◽  
Multiple Sources ◽  
P Waves ◽  
Moment Tensors ◽  
Additional Degree ◽  
S Waves

ABSTRACT High-resolution earthquake locations and structural inversions using body waves rely on precise delay-time measurements. Subsample accuracy can be realized for P waves using multichannel cross correlation (MCCC), as developed by VanDecar and Crosson (1990), which exploits redundancy in pairwise cross correlations to determine delays between similar waveforms in studies of mantle structure using teleseismic sources (common source and multiple stations) and regional studies of structure and seismicity (multiple sources and common station). For regional S waves, alignment is complicated by the additional degree of freedom in waveform polarity that is expressed for sources with different moment tensors. Here, we recast MCCC within a principal component framework and demonstrate the equivalence between maximizing waveform correlation and minimization of various singular value–based objective functions for P waves. The singular-value framework is more general and leads naturally to an MCCC linear system for S waves that possesses an order of magnitude greater redundancy than that for P waves. Robust L1 solution of the system provides an effective means of mitigating outliers at the expense of subsample precision. Residual time shifts associated with higher-order singular vectors are employed in an iterative adaptive alignment that achieves subsample resolution. We demonstrate application of the approach on a seismicity cluster within the northern Cascadia crustal fore-arc.

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