scholarly journals Locating microseismic sources with a single seismometer channel using coda wave interferometry

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. A19-A24 ◽  
Author(s):  
Youqian Zhao ◽  
Andrew Curtis ◽  
Brian Baptie
Keyword(s):  
Single Channel ◽  
Cost Effective ◽  
Coda Wave ◽  
Probabilistic Framework ◽  
Data Set ◽  
Cost Effective Method ◽  
Potential Applications ◽  
The Impact ◽  
Coda Wave Interferometry ◽  
Selection Of

A novel source location method based on coda wave interferometry (CWI) was applied to a microseismic data set of mining-induced events recorded in Nottinghamshire, England. CWI uses scattered waves in the coda of seismograms to estimate the differences between two seismic states. We used CWI to estimate the distances between pairs of earthquake locations, which are then used jointly to determine the relative location of a cluster of events using a probabilistic framework. We evaluated two improvements to this location technique: These account for the impact of a large difference in the dominant wavelength of a recording made on different instruments, and they standardize the selection of parameters to be used when implementing the method. Although the method has been shown to produce reasonable estimates on larger earthquakes, we tested the method for microseismic events with shorter distinguishable codas in recorded waveforms, and hence, fewer recorded scattered waves. The earthquake location results are highly consistent when using different individual seismometer channels, showing that it is possible to locate event clusters with a single-channel seismometer. We thus extend the potential applications of this cost-effective method to seismic events over a wider range of magnitudes.

scholarly journals Relative source location using coda-wave interferometry: Method, code package, and application to mining-induced earthquakes

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. F73-F84 ◽  
Author(s):  
Youqian Zhao ◽  
Andrew Curtis
Keyword(s):  
Single Channel ◽  
Source Region ◽  
Source Location ◽  
Coda Wave ◽  
Data Set ◽  
Seismic Stations ◽  
Location Method ◽  
Wide Range ◽  
Single Station ◽  
Coda Wave Interferometry

A wide range of applications requires the relative locations of sources of energy to be known accurately. Most conventional location methods are either subject to errors that depend strongly on inaccuracy in the model of propagation velocity used or demand a well-distributed network of surrounding seismic stations to produce reliable results. A new source location method based on coda-wave interferometry (CWI) is relatively insensitive to the number of seismic stations and to the source-to-station azimuthal coverage. Therefore, it opens new avenues for research, for applications in areas with unfavorable recording geometries, and for applications that require a complementary method. This method uses CWI to estimate distances between pairs of seismic events with a similar source mechanism recorded at the same station. These separation estimates are used to solve for the locations of clusters of events relative to one another within a probabilistic framework through optimization. It is even possible to find the relative locations of clusters of events with one single-channel station. Given these advantages, it is likely that one reason that the method is not used more widely is the lack of reliable code that implements this multistage method. Therefore, we have developed a well-commented MATLAB code that does so, and we evaluate examples of its applications. It can be used with seismic data from a single-station channel, and it enables data recorded by different channels and stations to be used simultaneously. It is therefore possible to combine data from permanent yet sparse networks and from temporary arrays closer to the source region. We use the code to apply the location method to a selected data set of the New Ollerton earthquakes in England to demonstrate the validity of the code. The worked example is provided within the package. A way to assess the quality of the location results is also provided.

scholarly journals Sensitivity of Ultrasonic Coda Wave Interferometry to Material Damage—Observations from a Virtual Concrete Lab

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4033
Author(s):  
Claudia Finger ◽  
Leslie Saydak ◽  
Giao Vu ◽  
Jithender J. Timothy ◽  
Günther Meschke ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Concrete Specimen ◽  
Coda Wave ◽  
Velocity Change ◽  
Damage Scenarios ◽  
Different Types ◽  
Source Signal ◽  
The Impact ◽  
Structural Scale ◽  
Coda Wave Interferometry

Ultrasonic measurements are used in civil engineering for structural health monitoring of concrete infrastructures. The late portion of the ultrasonic wavefield, the coda, is sensitive to small changes in the elastic moduli of the material. Coda Wave Interferometry (CWI) correlates these small changes in the coda with the wavefield recorded in intact, or unperturbed, concrete specimen to reveal the amount of velocity change that occurred. CWI has the potential to detect localized damages and global velocity reductions alike. In this study, the sensitivity of CWI to different types of concrete mesostructures and their damage levels is investigated numerically. Realistic numerical concrete models of concrete specimen are generated, and damage evolution is simulated using the discrete element method. In the virtual concrete lab, the simulated ultrasonic wavefield is propagated from one transducer using a realistic source signal and recorded at a second transducer. Different damage scenarios reveal a different slope in the decorrelation of waveforms with the observed reduction in velocities in the material. Finally, the impact and possible generalizations of the findings are discussed, and recommendations are given for a potential application of CWI in concrete at structural scale.

Quantitative Selection of Variation Reduction Plans

1998 ◽  
Author(s):  
Anna C. Thornton
Keyword(s):  
Risk Mitigation ◽  
Cost Effective ◽  
Variation Reduction ◽  
Multiple Quality Characteristics ◽  
Cost Effective Approach ◽  
Manufacturing Performance ◽  
The Impact ◽  
Manufacturing Variation ◽  
Selection Of

Abstract Quality has been a rallying call in the design and manufacturing world for the last two decades. One way to improve quality is to reduce the impact of manufacturing variation. Variation risk mitigation is challenging especially when a product has multiple quality characteristics and complex production and assembly. It is common wisdom that companies should identify and mitigate the risk associated with variation throughout the design process. As yield problems are identified, they should be mitigated using the most cost effective approach. One approach to variation risk mitigation is variation reduction (VR). VR targets reduction of variation introduced by existing manufacturing processes using tools such as Design of Experiments (DOE) and robust design. Many companies have specialized groups that specialize in these methods. VR teams have the role of improving manufacturing performance; however, these teams are limited in their resources. In addition, no tools exist to quantitatively determine where a VR team’s efforts are most effectively deployed. This paper provides a mathematical and optimization model to best allocate VR resources in a complex product.

scholarly journals Biosynthesis and Potential Applications of Silver and Gold Nanoparticles and Their Chitosan-Based Nanocomposites in Nanomedicine

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Haliza Katas ◽  
Noor Zianah Moden ◽  
Chei Sin Lim ◽  
Terence Celesistinus ◽  
Jie Yee Chan ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Metallic Nanoparticles ◽  
Cost Effective ◽  
One Pot ◽  
Silver And Gold Nanoparticles ◽  
Stabilizing Agents ◽  
Cost Effective Method ◽  
Multistep Process ◽  
Potential Applications ◽  
Biological Sources

Biosynthesized or biogenic metallic nanoparticles, particularly silver and gold nanoparticles (AgNPs and AuNPs, respectively), have been increasingly used because of their advantages, including high stability and loading capacity; moreover, these nanoparticles are synthesized using a green and cost-effective method. Previous studies have investigated reducing and/or stabilizing agents from various biological sources, including plants, microorganisms, and marine-derived products, using either a one-pot or a multistep process at different conditions. In addition, extensive studies have been performed to determine the biological or pharmacological effects of these nanoparticles, such as antimicrobial, antitumor, anti-inflammatory, and antioxidant effects. In the recent years, chitosan, a natural cationic polysaccharide, has been increasingly investigated as a reducing and/or stabilizing agent in the synthesis of biogenic metallic nanoparticles with potential applications in nanomedicine. Here, we have reviewed the mechanism of biosynthesis and potential applications of AgNPs and AuNPs and their chitosan-mediated nanocomposites in nanomedicine.

scholarly journals Improvement of the Impact Properties of Composite Laminates by Means of Nano-Modification of the Matrix—A Review

2018 ◽  
Vol 8 (12) ◽  
pp. 2406 ◽  
Author(s):  
Hamed Saghafi ◽  
Mohamad Fotouhi ◽  
Giangiacomo Minak
Keyword(s):  
Composite Laminates ◽  
Cost Effective ◽  
Careful Consideration ◽  
Impact Performance ◽  
Compression After Impact ◽  
The Matrix ◽  
The Right ◽  
2D And 3D ◽  
The Impact ◽  
Selection Of

This paper reviews recent works on the application of nanofibers and nanoparticle reinforcements to enhance the interlaminar fracture toughness, to reduce the impact induced damage and to improve the compression after impact performance of fiber reinforced composites with brittle thermosetting resins. The nanofibers have been mainly used as mats embedded between plies of laminated composites, whereas the nanoparticles have been used in 0D, 1D, 2D, and 3D dimensional patterns to reinforce the matrix and consequently the composite. The reinforcement mechanisms are presented, and a comparison is done between the different papers in the literature. This review shows that in order to have an efficient reinforcement effect, careful consideration is required in the manufacturing, materials selection and reinforcement content and percentage. The selection of the right parameters can provide a tough and impact resistant composite with cost effective reinforcements.

scholarly journals Improving Maternal and Child Health in Bangladesh: The Integration of Midwives in Conjunction With the United Nations Millenium Development Goals Initiative

2015 ◽  
Vol 3 ◽  
Author(s):  
Elizabeth Casto
Keyword(s):  
Child Health ◽  
United Nations ◽  
Maternal And Child Health ◽  
Millennium Development Goals ◽  
Cost Effective ◽  
Cost Effective Method ◽  
Development Goals ◽  
The United Nations ◽  
The Impact ◽  
And Child Health

As the United Nations Millennium Development Goals initiative comes to a close, it is important to examine what has been effective in combating disparities in developing nations. In this paper I explore the impact midwives have on improving maternal and child health in Bangladesh by focusing on how the United Nations Millennium Development Goals initiative has helped to change societal views on women and birth as midwives become more integrated into improving maternal and child health. It is a quantitative and qualitative approach analyzing the statistics of implementing midwives as these impact cost-effectiveness and change in mortality rates in addition to social changes that have occurred in the culture towards maternal and child health. The paper further analyzes programs implemented by countries such as India and Sri Lanka comparatively. Data have been collected from published United Nations and governmental reports, media, and research articles. The paper concludes that the implementation of midwives has provided a cost-effective method of reducing maternal and child health in Bangladesh, and will be increasingly efficient as governmental programs continue to improve various aspects and laws of the country. It is important to analyze what is working in order to further improve maternal and child health on both a regional and global level. The use of midwives can provide a fundamental framework in communities that can aid in reducing health disparities as well as all improve all facets of reproductive wellness, providing the support needed at all stages to improve maternal and child health.

scholarly journals High-end climate change impact on European runoff and low flows – exploring the effects of forcing biases

2016 ◽  
Vol 20 (5) ◽  
pp. 1785-1808 ◽  
Author(s):  
Lamprini V. Papadimitriou ◽  
Aristeidis G. Koutroulis ◽  
Manolis G. Grillakis ◽  
Ioannis K. Tsanis
Keyword(s):  
Global Warming ◽  
Bias Correction ◽  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Data Set ◽  
Low Flows ◽  
The Impact ◽  
Selection Of

Abstract. Climate models project a much more substantial warming than the 2 °C target under the more probable emission scenarios, making higher-end scenarios increasingly plausible. Freshwater availability under such conditions is a key issue of concern. In this study, an ensemble of Euro-CORDEX projections under RCP8.5 is used to assess the mean and low hydrological states under +4 °C of global warming for the European region. Five major European catchments were analysed in terms of future drought climatology and the impact of +2 °C versus +4 °C global warming was investigated. The effect of bias correction of the climate model outputs and the observations used for this adjustment was also quantified. Projections indicate an intensification of the water cycle at higher levels of warming. Even for areas where the average state may not considerably be affected, low flows are expected to reduce, leading to changes in the number of dry days and thus drought climatology. The identified increasing or decreasing runoff trends are substantially intensified when moving from the +2 to the +4° of global warming. Bias correction resulted in an improved representation of the historical hydrology. It is also found that the selection of the observational data set for the application of the bias correction has an impact on the projected signal that could be of the same order of magnitude to the selection of the Global Climate Model (GCM).

Generation of “Biking Schedules” for Bicycle Travel Analysis

2018 ◽  
Vol 2672 (36) ◽  
pp. 83-91 ◽  
Author(s):  
Amr Mohamed ◽  
Alexander Y. Bigazzi
Keyword(s):  
Data Sets ◽  
Calibration Data ◽  
Data Set ◽  
Construction Methods ◽  
Potential Applications ◽  
Road Grade ◽  
Calibration Data Set ◽  
Future Work ◽  
The Impact ◽  
Travel Analysis

With an increasing focus on bicycling as a mode of urban transportation, there is a pressing need for improved tools for bicycle travel analysis and modeling. This paper introduces “biking schedules” to represent archetypal urban cycling dynamics, analogous to driving schedules used in vehicle emissions analysis. Three different methods of constructing biking schedules with both speed and road grade attributes are developed from the driving schedule literature. The methods are applied and compared using a demonstration data set of 55 h of 1-Hz on-road GPS data from three cyclists. Biking schedules are evaluated based on their ability to represent the speed dynamics, power output, and breathing rates of a calibration data set and then validated for different riders. The impact of using coarser 3, 5, and 10 s GPS logging intervals on the accuracy of the schedules is also evaluated. Results indicate that the best biking schedule construction method depends on the volume and resolution of the calibration data set. Overall, the biking schedules successfully represent most of the assessed characteristics of cycling dynamics in the calibration data set (speed, acceleration, grade, power, and breathing) within 5%. Future work will examine the precision of biking schedules constructed from larger data sets in more diverse cycling conditions and explore additional refinements to the construction methods. This research is considered a first step toward adopting biking schedules in bicycle travel analysis and modeling, and potential applications are discussed.

Mediation in Territorial, Maritime and River Disputes

2014 ◽  
Vol 19 (2) ◽  
pp. 343-370 ◽  
Author(s):  
Krista E. Wiegand
Keyword(s):  
Strong Influence ◽  
Strong Impact ◽  
Data Set ◽  
The Impact ◽  
Selection Of ◽  
Communications Strategies

This article seeks to explain factors that make mediation attempts more or less likely in territorial, maritime, and river disputes. I argue that the intensity of the dispute and the salience of disputed territory have strong influence on mediation attempts. The study further examines the impact of these factors on the type of mediation strategy (directive, procedural, or communications). Hypotheses about mediation attempts are tested with the icow data set of interstate territorial, maritime, and river disputes from 1816 to 2001. Findings indicate that intensity of the dispute and salience of disputed territory have a strong impact on the selection of mediation in the first place, and second, that salience of disputed territory makes the directive strategy more likely, while intensity of the dispute makes procedural or communications strategies more likely.

scholarly journals The Impact of Normalization Methods on RNA-Seq Data Analysis

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
J. Zyprych-Walczak ◽  
A. Szabelska ◽  
L. Handschuh ◽  
K. Górczak ◽  
K. Klamecka ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Data Sets ◽  
Complex Data ◽  
Rna Seq ◽  
Medical Problems ◽  
Data Set ◽  
Normalization Methods ◽  
Wide Range ◽  
The Impact ◽  
Selection Of

High-throughput sequencing technologies, such as the Illumina Hi-seq, are powerful new tools for investigating a wide range of biological and medical problems. Massive and complex data sets produced by the sequencers create a need for development of statistical and computational methods that can tackle the analysis and management of data. The data normalization is one of the most crucial steps of data processing and this process must be carefully considered as it has a profound effect on the results of the analysis. In this work, we focus on a comprehensive comparison of five normalization methods related to sequencing depth, widely used for transcriptome sequencing (RNA-seq) data, and their impact on the results of gene expression analysis. Based on this study, we suggest a universal workflow that can be applied for the selection of the optimal normalization procedure for any particular data set. The described workflow includes calculation of the bias and variance values for the control genes, sensitivity and specificity of the methods, and classification errors as well as generation of the diagnostic plots. Combining the above information facilitates the selection of the most appropriate normalization method for the studied data sets and determines which methods can be used interchangeably.

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