SEARCH FOR STEADY AND TRANSIENT POINT-LIKE SOURCES OF NEUTRINOS WITH ANTARES

2009 ◽  
Vol 18 (10) ◽  
pp. 1505-1509
Author(s):  
◽  
CIRO BIGONGIARI
Keyword(s):  
Short Duration ◽  
Angular Resolution ◽  
Signal To Noise Ratio ◽  
High Energy ◽  
Neutrino Telescope ◽  
Signal To Noise ◽  
Transient Sources ◽  
High Energy Neutrinos ◽  
Noise Ratio ◽  
Better Than

The ANTARES underwater neutrino telescope has been completed in May 2008 and is now taking data continuously. Thanks to its very good angular resolution (better than 0.3° for neutrinos with energy above 10 TeV) ANTARES is especially suited for the search of astrophysical point-like sources of high energy neutrinos. Data taken with a limited detector (5 out of 12 lines) between January and December 2007 have been analyzed to look for a possible neutrino excess from a list of prospective neutrino sources. In the case of transient sources, like GRBs, the short duration of the expected neutrino signal can be exploited to enhance the signal to noise ratio. ANTARES strategy for both steady and transient point-like sources is discussed. The methodology adopted and the results obtained are shown.

MIMO Detectors: A Comprehensive Performance Analysis

2021 ◽  
Vol 16 (3) ◽  
pp. 24-27
Author(s):  
E. Obi ◽  
B.O. Sadiq ◽  
O.S . Zakariyya ◽  
A. Theresa
Keyword(s):  
Error Rate ◽  
Mimo Systems ◽  
Signal To Noise Ratio ◽  
Minimum Mean Square Error ◽  
Multiple Input Multiple Output ◽  
Symbol Error Rate ◽  
Signal To Noise ◽  
High Data ◽  
Noise Ratio ◽  
Better Than

Multiple-input multiple-output (MIMO) systems are increasingly becoming popular due to their ability to multiply data rates without any expansion in the bandwidth. This is critical in this era of high-data rate applications but limited bandwidth. MIMO detectors play an important role in ensuring effective communication in such systems and as such the performance of the following are compared in this paper with respect to symbol error rate (SER) versus signal-to-noise ratio (SNR): maximum likelihood (ML), zero forcing (ZF), minimum mean square error (MMSE) and vertical Bell laboratories layered space time (VBLAST). Results showed that the ML has the best performance as it has the least Symbol Error Rate (SER) for all values of Signal to Noise Ratio (SNR) as it was 91.9% better than MMSE, 99.6% better than VBLAST and 99.8% better than ZF at 20db for a 2x2 antenna configuration., it can also be deduced that the performance increased with increase in number of antenna for all detectors except the V-BLAST detector.

A Comparison of 25 Gbps NRZ & PAM-4 Modulation Used in Reference, Legacy, & Premium Backplane Channels

2012 ◽  
Vol 2012 (1) ◽  
pp. 000283-000294 ◽  
Author(s):  
Chad Morgan ◽  
Adam Healey
Keyword(s):  
Insertion Loss ◽  
Signal To Noise Ratio ◽  
High Density ◽  
Advanced Materials ◽  
Signal To Noise ◽  
Baud Rate ◽  
Noise Ratio ◽  
Better Than

Standards bodies are now examining how to increase the throughput of high-density backplane links to 25 Gbps. One method for achieving this is to construct premium backplane links utilizing advanced materials and connectors. Another approach is to re-use legacy backplanes by employing PAM-4 signaling at half of the baud rate. For PAM-4 to offer an advantage over NRZ, the signal-to-noise ratio (SNR) at the slicer input, i.e. after equalization, must be ∼9.5 dB better than NRZ to overcome loss of separation between signal levels. This paper will examine 25 Gbaud NRZ and 12.5 Gbaud PAM-4 signaling across varying levels of channel insertion loss and crosstalk. The paper provides a reliable reference for engineers to use when considering when it is appropriate to use NRZ signaling at 25 Gbaud and when it is appropriate to use PAM-4 signaling at 12.5 Gbaud for successful high-density backplane operation.

scholarly journals The Information of Images and Its Dependence on Noise and Spatial Resolution

1979 ◽  
Vol 49 ◽  
pp. 249-255
Author(s):  
Peter M.W. Kalberla
Keyword(s):  
Spatial Resolution ◽  
Angular Resolution ◽  
Signal To Noise Ratio ◽  
Missing Information ◽  
Signal To Noise ◽  
Incomplete Coverage ◽  
Noise Ratio

Radioastronomical observations are often incomplete in the sense that either the angular resolution desired or the signal-to-noise ratio required are not adequate. Attempts to fill in the missing information by either smoothing or deconvolving the observed data date back to Bracewell (1956, 1958). More recently the need for more sophisticated restoration procedures has increased since observations with radioastronomical interferometers frequently suffer from incomplete coverage of the u – v plane. Procedures like CLEAN (Högbom 1974, Schwarz 1978) and MEM (Wernecke 1977, Gull and Daniell 1978) have been developed to interpolate the unknown data in the u – v plane.

A CONDENSER MEMORY UNIT FOR IMPROVING SIGNAL-TO-NOISE RATIOS

1960 ◽  
Vol 38 (3) ◽  
pp. 346-353 ◽  
Author(s):  
D. M. Hunten
Keyword(s):  
Signal To Noise Ratio ◽  
Original Version ◽  
Square Root ◽  
Memory Unit ◽  
Signal To Noise ◽  
Low Leakage ◽  
Recent Modification ◽  
Noise Ratio ◽  
Better Than

The unit contains 30 low-leakage condensers which can store a signal for several hours if necessary. If the signal is repeated over and over, the successive scans can be added in and the signal-to-noise ratio builds up as the square root of the number of repetitions. In principle, the final signal-to-noise ratio is only slightly better than would be obtained from a single scan stretched out to fill the same total time, but in practice the result may be considerably better, especially if the signal fluctuates slowly. It has been used successfully in several investigations of twilight spectra with photoelectric and photoconductive spectrometers. The original version took 1 minute per scan and was rather bulky; a recent modification can scan 32 channels in 10 seconds if required.

scholarly journals One Year of Seismicity Recorded Through Ocean Bottom Seismometers Illuminates Active Tectonic Structures in the Ionian Sea (Central Mediterranean)

2021 ◽  
Vol 9 ◽  
Author(s):  
Tiziana Sgroi ◽  
Alina Polonia ◽  
Laura Beranzoli ◽  
Andrea Billi ◽  
Alessandro Bosman ◽  
...  
Keyword(s):  
Short Duration ◽  
Signal To Noise Ratio ◽  
Ocean Bottom ◽  
Ionian Sea ◽  
Signal To Noise ◽  
Local Earthquakes ◽  
Seismological Data ◽  
Ocean Bottom Seismometers ◽  
Seismogenic Structures ◽  
Noise Ratio

Seismological data recorded in the Ionian Sea by a network of seven Ocean Bottom Seismometers (OBSs) during the 2017–2018 SEISMOFAULTS experiment provides a close-up view of seismogenic structures that are potential sources of medium-high magnitude earthquakes. The high-quality signal-to-noise ratio waveforms are observed for earthquakes at different scales: teleseismic, regional, and local earthquakes as well as single station earthquakes and small crack events. In this work, we focus on two different types of recording: 1) local earthquakes and 2) Short Duration Events (SDE) associated to micro-fracturing processes. During the SEISMOFAULTS experiment, 133 local earthquakes were recorded by both OBSs and land stations (local magnitude ranging between 0.9 and 3.8), while a group of local earthquakes (76), due to their low magnitude, were recorded only by the OBS network. We relocated 133 earthquakes by integrating onshore and offshore travel times and obtaining a significant improvement in accuracy, particularly for the offshore events. Moreover, the higher signal-to-noise ratio of the OBS network revealed a significant seismicity not detected onshore, which shed new light on the location and kinematics of seismogenic structures in the Calabrian Arc accretionary prism and associated to the subduction of the Ionian lithosphere beneath the Apennines. Other signals recorded only by the OBS network include a high number of Short Duration Events (SDE). The different waveforms of SDEs at two groups of OBSs and the close correlation between the occurrence of events recorded at single stations and SDEs suggest an endogenous fluid venting from mud volcanoes and active fault traces. Results from the analysis of seismological data collected during the SEISMOFAULTS experiment confirm the necessity and potential of marine studies with OBSs, particularly in those geologically active areas of the Mediterranean Sea prone to high seismic risk.

scholarly journals Missing [C ii] emission from early galaxies

2020 ◽  
Vol 499 (4) ◽  
pp. 5136-5150 ◽  
Author(s):  
S Carniani ◽  
A Ferrara ◽  
R Maiolino ◽  
M Castellano ◽  
S Gallerani ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Angular Resolution ◽  
Signal To Noise Ratio ◽  
Line Emission ◽  
Continuum Emission ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Hydrodynamical Simulations ◽  
Early Galaxies

ABSTRACT ALMA observations have revealed that [C ii] 158 μm line emission in high-z galaxies is ≈2–3 × more extended than the UV continuum emission. Here we explore whether surface brightness dimming (SBD) of the [C ii] line is responsible for the reported [C ii] deficit, and the large $L_{\rm [O\, \small {III}]}/L_{\rm [C\, \small {II}]}$ luminosity ratio measured in early galaxies. We first analyse archival ALMA images of nine z > 6 galaxies observed in both [C ii] and [O iii]. After performing several uv-tapering experiments to optimize the identification of extended line emission, we detect [C ii] emission in the whole sample, with an extent systematically larger than the [O iii] emission. Next, we use interferometric simulations to study the effect of SBD on the line luminosity estimate. About 40 per cent of the extended [C ii] component might be missed at an angular resolution of 0.8 arcsec, implying that $L_{\rm [C\, \small {II}]}$ is underestimated by a factor ≈2 in data at low (<7) signal-to-noise ratio. By combining these results, we conclude that $L_{\rm [C\, \small {II}]}$ of z > 6 galaxies lies, on average, slightly below the local $L_{\rm [C\, \small {II}]}-\mathrm{ SFR}$ relation (Δz =  6–9 = −0.07 ± 0.3), but within the intrinsic dispersion of the relation. SBD correction also yields $L_{\rm [O\, \small {III}]}/L_{\rm [C\, \small {II}]}\lt 10$, i.e. more in line with current hydrodynamical simulations.

scholarly journals Modifikasi Ant Colony Optimization Berdasarkan Gradient Untuk Deteksi Tepi Citra

2015 ◽  
Vol 6 (3) ◽  
Author(s):  
Febri Liantoni ◽  
Nanik Suciati ◽  
Chastine Fatichah
Keyword(s):  
Edge Detection ◽  
Ant Colony Optimization ◽  
Signal To Noise Ratio ◽  
Ant Colony ◽  
Test Results ◽  
Signal To Noise ◽  
Average Value ◽  
Image Edge ◽  
Noise Ratio ◽  
Better Than

Abstract. Ant Colony Optimization (ACO) is an optimization algorithm which can be used for image edge detection. In traditional ACO, the initial ant are randomly distributed. This condition can cause an imbalance ants distribution. Based on this problem, a modified ant distribution in ACO is proposed to optimize the deployment of ant based gradient. Gradient value is used to determine the placement of the ants. Ants are not distributed randomly, but are placed in the highest gradient. This method is expected to be used to optimize the path discovery. Based on the test results, the use of the proposed ACO modification can obtain an average value of the Peak Signal to Noise Ratio (PSNR) of 12.724. Meanwhile, the use of the traditional ACO can obtain an average value of PSNR of 12.268. These results indicate that the ACO modification is capable of generating output image better than traditional ACO in which ants are initially distributed randomly.Keywords: Ant Colony Optimization, gradient, Edge Detection, Peak Signal to Noise Ratio Abstrak. Ant Colony Optimization (ACO) merupakan algoritma optimasi, yang dapat digunakan untuk deteksi tepi pada citra Pada ACO tradisional, semut awal disebarkan secara acak. Kondisi ini dapat menyebabkan ketidakseimbangan distribusi semut. Berdasarkan permasalahan tersebut, modifikasi distribusi semut pada ACO diusulkan untuk mengoptimalkan penempatan semut berdasarkan gradient. Nilai gradient digunakan untuk menentukan penempatan semut. Semut tidak disebar secara acak akan tetapi ditempatkan di gradient tertinggi. Cara ini diharapkan dapat digunakan untuk optimasi penemuan jalur. Berdasarkan hasil uji coba, dengan menggunakan ACO modifikasi yang diusulkan dapat diperoleh nilai rata-rata Peak Signal to Noise Ratio (PSNR) 12,724. Sedangkan, menggunakan ACO tradisional diperoleh nilai rata-rata PSNR 12,268. Hasil ini menunjukkan bahwa ACO modifikasi mampu menghasilkan citra keluaran yang lebih baik dibandingkan ACO tradisional yang sebaran semut awalnya dilakukan secara acak.Kata Kunci: Ant Colony Optimization, gradient, deteksi tepi, Peak Signal to Noise Ratio

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