The Anza array: A high-dynamic-range, broadband, digitally radiotelemetered seismic array

1984 ◽  
Vol 74 (4) ◽  
pp. 1469-1481
Author(s):  
Jon Berger ◽  
L. M. Baker ◽  
J. N. Brune ◽  
J. B. Fletcher ◽  
T. C. Hanks ◽  
...  
Keyword(s):  
Large Scale ◽  
Scaling Laws ◽  
Dynamic Range ◽  
Body Wave ◽  
Sampling Rate ◽  
Digital Transmission ◽  
High Dynamic Range ◽  
Seismic Array ◽  
High Rate ◽  
Small Aperture

Abstract A small aperture seismic array has been deployed along a 30-km stretch of the San Jacinto fault in the vicinity of the town of Anza, California. The array was installed to study specifically the scaling laws of body-wave spectra, the character of high-frequency ground motion, the physical interpretation of seismic stress drops, and the interaction of earthquakes. This region was chosen for these studies due to its high rate of seismic activity in the 2 ≦ M ≦ 4.5 range, the likelihood of a M > 6 event in the next decade, and the existence of the Southern California Batholith on either side of the fault, reducing problems associated with attenuation and large scale anisotropy. These studies employ an instrument package with a frequency response of 100 Hz, a dynamic range of 138 dB, a sampling rate of 250 times per second per component, and a 16-bit A/D converter. The array consists of 10 three-component stations, telemetered via digital VHF radio to a nearby mountain peak and thence via a microwave link to La Jolla, California. A minicomputer system monitors the array's performance, detects events, and records data upon demand. Initial results demonstrate the feasibility of digital transmission with an inherent increase in data quality over analog systems.

scholarly journals SOI-Based Multi-Channel AWG with Fiber Bragg Grating Sensing Interrogation System

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 214
Author(s):  
Siming Weng ◽  
Pei Yuan ◽  
Wei Zhuang ◽  
Dongliang Zhang ◽  
Fei Luo ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
High Rate ◽  
Bragg Grating ◽  
Arrayed Waveguide Grating ◽  
High Agreement ◽  
High Dynamic ◽  
Critical Components ◽  
Arrayed Waveguide

For the development of minimized and high-rate photonic-integrated fiber Bragg grating interrogation (FBGI) systems, arrayed waveguide grating (AWG) has been widely used as one of the critical components. In this paper, we present an 8-channel SOI-based AWG for a photonic integrated FBG interrogation microsystem. The channel spacing of the AWG is designed to be 3 nm to meet a high-dynamic-range demodulation requirement. The core size of the fabricated AWG is about 335 × 335 μm2. The simulation results and experimental results are in high agreement, showing that AWG has a fine transmission spectrum with crosstalk below −16 dB, nonuniformity below 0.4 dB, insertion loss below −6.35 dB, 3 dB bandwidth about 1.3 nm and 10 dB bandwidth of 2.3 nm. The proposed AWG can be applied perfectly to the SOI-based AWG demodulation microsystem, exhibiting a large dynamic range of 1.2 nm, the resolution for measurements is 1.27 pm and a high accuracy of 20.6 pm.

scholarly journals INSTALLATION AND PRELIMINARY RESULTS FROM A SMALL APERTURE SEISMIC ARRAY IN TRIPOLI, GREECE

2004 ◽  
Vol 36 (3) ◽  
pp. 1499 ◽  
Author(s):  
M. Pirli ◽  
Ν. Voulgaris ◽  
J. Alexopoulos ◽  
K. Makropoulos
Keyword(s):  
Body Wave ◽  
Seismic Array ◽  
Small Aperture ◽  
Preliminary Results ◽  
Seismic Waveforms ◽  
Equipment Safety ◽  
Array Calibration ◽  
Array Performance ◽  
The University ◽  
Of Greece

A small aperture seismic array was installed by the University of Athens, in the area of Tripoli, Greece, on July 16th 2003, in order to test the performance of seismic array processing in the area of Greece and assess its contribution to earthquake location, especially in offshore areas not azimuthally covered by the existing, conventional seismological networks. The array consists of four three-component seismological stations, one of them in the middle of a small, almost equilateral triangle, formed by the deployment of the other three stations. Despite the fact that array siting is a compromise of array installation criteria, equipment safety and logistics, the test character of the experiment can be served successfully. The array transfer function depicts good azimuthal coverage nonetheless the existence of side-lobes and a rather wide main lobe is characteristic of spatial aliasing and low resolution in the two-dimensional wavenumber domain. The resolvable wavenumber passband of the array permits the determination of most of the common seismic body wave phases (Pn, Pg, Sn, Sg, etc.) for local and regional events in the area of Greece. Location of recorded events was performed using slowness and backazimuth data, calculated by f-k analysis of the seismic waveforms. Preliminary results have been compared to epicentres calculated by the Geodynamic Institute of the National Observatory of Athens. Although some differences are observed, these are not significant and location results as well as overall array performance can be improved by array calibration and travel-time, azimuth and slowness correction calculations.

scholarly journals Modular operation of microfluidic chips for highly parallelized cell culture and liquid dosing via a fluidic circuit board

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
A. R. Vollertsen ◽  
D. de Boer ◽  
S. Dekker ◽  
B. A. M. Wesselink ◽  
R. Haverkate ◽  
...  
Keyword(s):  
Cell Culture ◽  
Large Scale ◽  
Dynamic Range ◽  
Umbilical Vein ◽  
Building Blocks ◽  
High Dynamic Range ◽  
Microfluidic System ◽  
Circuit Board ◽  
Microfluidic Chips ◽  
Umbilical Vein Endothelial Cells

AbstractMicrofluidic systems enable automated and highly parallelized cell culture with low volumes and defined liquid dosing. To achieve this, systems typically integrate all functions into a single, monolithic device as a “one size fits all” solution. However, this approach limits the end users’ (re)design flexibility and complicates the addition of new functions to the system. To address this challenge, we propose and demonstrate a modular and standardized plug-and-play fluidic circuit board (FCB) for operating microfluidic building blocks (MFBBs), whereby both the FCB and the MFBBs contain integrated valves. A single FCB can parallelize up to three MFBBs of the same design or operate MFBBs with entirely different architectures. The operation of the MFBBs through the FCB is fully automated and does not incur the cost of an extra external footprint. We use this modular platform to control three microfluidic large-scale integration (mLSI) MFBBs, each of which features 64 microchambers suitable for cell culturing with high spatiotemporal control. We show as a proof of principle that we can culture human umbilical vein endothelial cells (HUVECs) for multiple days in the chambers of this MFBB. Moreover, we also use the same FCB to control an MFBB for liquid dosing with a high dynamic range. Our results demonstrate that MFBBs with different designs can be controlled and combined on a single FCB. Our novel modular approach to operating an automated microfluidic system for parallelized cell culture will enable greater experimental flexibility and facilitate the cooperation of different chips from different labs.

scholarly journals The Sun at the VLA's Metric and Decimetric Wavelengths

1990 ◽  
Vol 142 ◽  
pp. 523-524
Author(s):  
S. M. White ◽  
M. R. Kundu ◽  
N. Gopalswamy ◽  
E. J. Schmahl
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Active Regions ◽  
High Dynamic Range ◽  
The Sun ◽  
Large Array ◽  
Very Large Array ◽  
Preliminary Results ◽  
High Dynamic ◽  
Coronal Structures

During September 1988 (International Solar Month) we observed the Sun with the Very Large Array on 4 days in the period Sep. 11-17. The VLA was in its most compact configuration, which is ideal for studying large-scale coronal structures. Here we summarize some preliminary results of the observations at 0.333 and 1.5 GHz. Despite the presence of numerous active regions the Sun was actually very quiet, with no flares during our observing, and this allowed us to make high-dynamic-range maps.

High fidelity spectroscopic imaging at low radio frequencies to estimate plasma parameters of solar coronal mass ejections at higher coronal heights

2021 ◽  
Author(s):  
Devojyoti Kansabanik ◽  
Surajit Mondal ◽  
Divya Oberoi ◽  
Angelos Vourlidas
Keyword(s):  
Radio Emission ◽  
Coronal Mass Ejections ◽  
Large Scale ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Physical Parameters ◽  
Plasma Parameters ◽  
Radio Imaging ◽  
Gyrosynchrotron Emission ◽  
Murchison Widefield Array

<p>Coronal Mass Ejections (CMEs) are large-scale explosive eruptions of magnetised plasma from the Sun into the Heliosphere. Measuring the physical parameters of CMEs is crucial for understanding their physics and for assessing their geo-effectiveness. Radio observations offer the most direct means for estimating these plasma parameters when gyrosynchrotron (GS) emission is detected from the CME plasma. However, since the first detection by Bastian et al.2001, only a handful of studies have successfully detected GS emission from CME plasma. This is usually attributed to the challenges involved in obtaining the high dynamic range imaging required for observing this faint gyrosynchrotron emission in the vicinity of active solar emissions.</p><p>The newly developed imaging pipeline (Mondal et al., 2019) designed for the data from Murchison Widefield Array (MWA) marks a significant improvement in metrewave solar radio imaging. Our work suggests that we should now be able to routinely detect GS emission from CME plasma. We present an example where we have successfully detected radio emission from CME plasma and modelled it as GS emission, leading to reliable estimates of CME magnetic field as well as the distribution of energetic electrons (Mondal et al. 2020). In a different example we are able to detect the radio emission from the CME plasma out to as far as 8.3 solar radii. We find that the observed spectra are not always consistent with simple GS models. This highlights that more complicated physics might be at play and points to the need for building more detailed models for interpreting these emissions. We hope that with the availability of polarimetric imaging capability, which we are in the process of developing, this technique will provide a robust way to routinely measure CME magnetic fields along with its other physical parameters. We note that these are the weakest detections of GS emissions from CME plasma reported yet.</p>

85-1: Visually Lossless Compression of High Dynamic Range Images: A Large-Scale Evaluation

2018 ◽  
Vol 49 (1) ◽  
pp. 1151-1154 ◽  
Author(s):  
Aishwarya Sudhama ◽  
Matthew D. Cutone ◽  
Yuqian Hou ◽  
James Goel ◽  
Dale Stolitzka ◽  
...  
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Lossless Compression ◽  
High Dynamic Range ◽  
Range Images ◽  
Scale Evaluation ◽  
High Dynamic

scholarly journals A Fast and Reliable Luma Control Scheme for High-Quality HDR/WCG Video

2018 ◽  
Vol 8 (10) ◽  
pp. 1975 ◽  
Author(s):  
Tae-Young Kim ◽  
Yong-Goo Kim
Keyword(s):  
Dynamic Range ◽  
Sampling Rate ◽  
Optimal Solution ◽  
High Dynamic Range ◽  
Consumer Electronics ◽  
Processing Unit ◽  
Fixed Amount ◽  
Control Scheme ◽  
Wide Color Gamut ◽  
Rate Conversion

The evolution of display technologies makes high dynamic range/wide color gamut (HDR/WCG) media of great interest in various applications including cinema, TV, blue-ray titles, and others. However, the HDR/WCG media format for consumer electronics requires the sampling rate conversion of chroma signals, resulting in a quality problem on the luminance perception of media, even without compression. In order to reduce such luminance perception problems, this paper proposes a fast and reliable luma control scheme which takes advantage of the bounds on the best luma value derived from the solution based on truncated Taylor series. Simulations performed for an extensive comparison study demonstrate that the proposed algorithm significantly outperforms the previous representative fast luma control schemes, resulting in almost the same quality of the iterative optimal solution with a fixed amount of computations per processing unit.

scholarly journals DAYENU: a simple filter of smooth foregrounds for intensity mapping power spectra

2020 ◽  
Vol 500 (4) ◽  
pp. 5195-5213
Author(s):  
Aaron Ewall-Wice ◽  
Nicholas Kern ◽  
Joshua S Dillon ◽  
Adrian Liu ◽  
Aaron Parsons ◽  
...  
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Fourier Transforms ◽  
Power Spectra ◽  
High Dynamic Range ◽  
Spectrum Estimation ◽  
Sampled Data ◽  
Optimal Basis ◽  
Intensity Mapping ◽  
Band Limited

ABSTRACT We introduce DPSS Approximate lazY filtEriNg of foregroUnds (dayenu), a linear, spectral filter for H i intensity mapping that achieves the desirable foreground mitigation and error minimization properties of inverse co-variance weighting with minimal modelling of the underlying data. Beyond 21-cm power-spectrum estimation, our filter is suitable for any analysis where high dynamic-range removal of spectrally smooth foregrounds in irregularly (or regularly) sampled data is required, something required by many other intensity mapping techniques. Our filtering matrix is diagonalized by Discrete Prolate Spheroidal Sequences which are an optimal basis to model band-limited foregrounds in 21-cm intensity mapping experiments in the sense that they maximally concentrate power within a finite region of Fourier space. We show that dayenu enables the access of large-scale line-of-sight modes that are inaccessible to tapered discrete Fourier transform estimators. Since these modes have the largest SNRs,dayenu significantly increases the sensitivity of 21-cm analyses over tapered Fourier transforms. Slight modifications allow us to use dayenu as a linear replacement for iterative delay clean ing (dayenurest). We refer readers to the Code section at the end of this paper for links to examples and code.

scholarly journals Australian square kilometre array pathfinder: I. system description

2021 ◽  
Vol 38 ◽  
Author(s):  
A. W. Hotan ◽  
J. D. Bunton ◽  
A. P. Chippendale ◽  
M. Whiting ◽  
J. Tuthill ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Radio Telescopes ◽  
System Description ◽  
Square Kilometre Array ◽  
Science Operations ◽  
High Dynamic ◽  
Radio Transients

Abstract In this paper, we describe the system design and capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the conclusion of its construction project and commencement of science operations. ASKAP is one of the first radio telescopes to deploy phased array feed (PAF) technology on a large scale, giving it an instantaneous field of view that covers $31\,\textrm{deg}^{2}$ at $800\,\textrm{MHz}$ . As a two-dimensional array of 36 $\times$ 12 m antennas, with baselines ranging from 22 m to 6 km, ASKAP also has excellent snapshot imaging capability and 10 arcsec resolution. This, combined with 288 MHz of instantaneous bandwidth and a unique third axis of rotation on each antenna, gives ASKAP the capability to create high dynamic range images of large sky areas very quickly. It is an excellent telescope for surveys between 700 and $1800\,\textrm{MHz}$ and is expected to facilitate great advances in our understanding of galaxy formation, cosmology, and radio transients while opening new parameter space for discovery of the unknown.

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