scholarly journals Discrete interferences optimum beamformer in correlated signal and interfering noise

2022 ◽  
Vol 12 (2) ◽  
pp. 1732
Author(s):  
Satyanand Singh ◽  
Sajai Vir Singh ◽  
Dinesh Yadav ◽  
Sanjay Kumar Suman ◽  
Bhagyalakshmi Lakshminarayanan ◽  
...  
Keyword(s):  
Communication Networks ◽  
Antenna Arrays ◽  
Analytical Formula ◽  
Point Sources ◽  
Multiple Point ◽  
Interference Signal ◽  
Correlated Noise ◽  
Wide Range ◽  
Minimum Variance Distortionless Response ◽  
Noise Ratio

This paper introduces a significant special situation where the noise is a collection of D-plane interference signals and the correlated noise of D+1 is less than the number of array components. An optimal beamforming processor based on the minimum variance distortionless response (MVDR) generates and combines appropriate statistics for the D+1 model. Instead of the original space of the N-dimensional problem, the interference signal subspace is reduced to D+1. Typical antenna arrays in many modern communication networks absorb waves generated from multiple point sources. An analytical formula was derived to improve the signal to interference and noise ratio (SINR) obtained from the steering errors of the two beamformers. The proposed MVDR processor-based beamforming does not enforce general constraints. Therefore, it can also be used in systems where the steering vector is compromised by gain. Simulation results show that the output of the proposed beamformer based on the MVDR processor is usually close to the ideal state within a wide range of signal-to-noise ratio and signal-to-interference ratio. The MVDR processor-based beamformer has been experimentally evaluated. The proposed processor-based MVDR system significantly improves performance for large interference white noise ratio (INR) in the sidelobe region and provide an appropriate beam pattern.

scholarly journals Point spread function reconstruction of adaptive-optics imaging: meeting the astrometric requirements for time-delay cosmography

2021 ◽  
Vol 508 (1) ◽  
pp. 755-761
Author(s):  
Geoff C-F Chen ◽  
Tommaso Treu ◽  
Christopher D Fassnacht ◽  
Sam Ragland ◽  
Thomas Schmidt ◽  
...  
Keyword(s):  
Time Delay ◽  
Adaptive Optics ◽  
Point Spread Function ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Point Sources ◽  
Multiple Point ◽  
Point Spread ◽  
Wide Range ◽  
Spread Function

ABSTRACT Astrometric precision and knowledge of the point spread function are key ingredients for a wide range of astrophysical studies including time-delay cosmography in which strongly lensed quasar systems are used to determine the Hubble constant and other cosmological parameters. Astrometric uncertainty on the positions of the multiply-imaged point sources contributes to the overall uncertainty in inferred distances and therefore the Hubble constant. Similarly, knowledge of the wings of the point spread function is necessary to disentangle light from the background sources and the foreground deflector. We analyse adaptive optics (AO) images of the strong lens system J 0659+1629 obtained with the W. M. Keck Observatory using the laser guide star AO system. We show that by using a reconstructed point spread function we can (i) obtain astrometric precision of <1 mas, which is more than sufficient for time-delay cosmography; and (ii) subtract all point-like images resulting in residuals consistent with the noise level. The method we have developed is not limited to strong lensing, and is generally applicable to a wide range of scientific cases that have multiple point sources nearby.

Evaluation and Avoidance of False Alarm by Controlling Rhine Water with Continuously Working Biotests

1994 ◽  
Vol 29 (3) ◽  
pp. 207-209 ◽  
Author(s):  
H. Puzicha
Keyword(s):  
Warning System ◽  
Point Sources ◽  
Trophic Levels ◽  
River Rhine ◽  
Wide Range ◽  
River Test ◽  
Continuous Working ◽  
Range Of Variation ◽  
Contaminant Load ◽  
Rhine Water

Effluents from point sources (industries, communities) and diffuse inputs introduce pollutants into the water of the river Rhine and cause a basic contaminant load. The aim is to establish a biological warning system to detect increased toxicity in addition to the already existing chemical-physical monitoring system. To cover a wide range of biocides, continuous working biotests at different trophic levels (bacteria, algae, mussels, water fleas, fishes) have been developed and proved. These are checked out for sensitivity against toxicants, reaction time, validity of data and practical handling under field conditions at the river. Test-specific appropriate methods are found to differentiate between the normal range of variation and true alarm signals.

scholarly journals Towards a Glass New World: The Role of Ion-Exchange in Modern Technology

2021 ◽  
Vol 11 (10) ◽  
pp. 4610
Author(s):  
Simone Berneschi ◽  
Giancarlo C. Righini ◽  
Stefano Pelli
Keyword(s):  
Ion Exchange ◽  
Communication Networks ◽  
High Speed ◽  
High Performance ◽  
Low Cost ◽  
Modern Technology ◽  
Historical Background ◽  
Wide Range ◽  
Happy Marriage

Glasses, in their different forms and compositions, have special properties that are not found in other materials. The combination of transparency and hardness at room temperature, combined with a suitable mechanical strength and excellent chemical durability, makes this material indispensable for many applications in different technological fields (as, for instance, the optical fibres which constitute the physical carrier for high-speed communication networks as well as the transducer for a wide range of high-performance sensors). For its part, ion-exchange from molten salts is a well-established, low-cost technology capable of modifying the chemical-physical properties of glass. The synergy between ion-exchange and glass has always been a happy marriage, from its ancient historical background for the realisation of wonderful artefacts, to the discovery of novel and fascinating solutions for modern technology (e.g., integrated optics). Getting inspiration from some hot topics related to the application context of this technique, the goal of this critical review is to show how ion-exchange in glass, far from being an obsolete process, can still have an important impact in everyday life, both at a merely commercial level as well as at that of frontier research.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A18 ◽  
Author(s):  
C. H. A. Logan ◽  
B. J. Maughan ◽  
M. N. Bremer ◽  
P. Giles ◽  
M. Birkinshaw ◽  
...  
Keyword(s):  
Angular Resolution ◽  
False Positive Rate ◽  
High Sensitivity ◽  
Point Sources ◽  
Selection Function ◽  
X Rays ◽  
Cluster Emission ◽  
X Ray ◽  
Wide Range ◽  
Function Modelling

Context. The XMM-XXL survey has used observations from the XMM-Newton observatory to detect clusters of galaxies over a wide range in mass and redshift. The moderate PSF (FWHM ~ 6″ on-axis) of XMM-Newton means that point sources within or projected onto a cluster may not be separated from the cluster emission, leading to enhanced luminosities and affecting the selection function of the cluster survey. Aims. We present the results of short Chandra observations of 21 galaxy clusters and cluster candidates at redshifts z > 1 detected in the XMM-XXL survey in X-rays or selected in the optical and infra-red. Methods. With the superior angular resolution of Chandra, we investigate whether there are any point sources within the cluster region that were not detected by the XMM-XXL analysis pipeline, and whether any point sources were misclassified as distant clusters. Results. Of the 14 X-ray selected clusters, 9 are free from significant point source contamination, either having no previously unresolved sources detected by Chandra or with less than about 10% of the reported XXL cluster flux being resolved into point sources. Of the other five sources, one is significantly contaminated by previously unresolved AGN, and four appear to be AGN misclassified as clusters. All but one of these cases are in the subset of less secure X-ray selected cluster detections and the false positive rate is consistent with that expected from the XXL selection function modelling. We also considered a further seven optically selected cluster candidates associated with faint XXL sources that were not classed as clusters. Of these, three were shown to be AGN by Chandra, one is a cluster whose XXL survey flux was highly contaminated by unresolved AGN, while three appear to be uncontaminated clusters. By decontaminating and vetting these distant clusters, we provide a pure sample of clusters at redshift z > 1 for deeper follow-up observations, and demonstrate the utility of using Chandra snapshots to test for AGN in surveys with high sensitivity but poor angular resolution.

scholarly journals Improvement of signal-to-noise ratio in parallel neuron arrays with spatially nearest neighbor correlated noise

PLoS ONE ◽  
2018 ◽  
Vol 13 (7) ◽  
pp. e0200890
Author(s):  
Tianquan Feng ◽  
Qingrong Chen ◽  
Ming Yi ◽  
Zhongdang Xiao
Keyword(s):  
Nearest Neighbor ◽  
Signal To Noise Ratio ◽  
Correlated Noise ◽  
Signal To Noise ◽  
Noise Ratio

scholarly journals Analytical Formula for the Ratio of Central to Minimum Film Thickness in a Circular EHL Contact

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 80 ◽  
Author(s):  
Petr Sperka ◽  
Ivan Krupka ◽  
Martin Hartl
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Analytical Formula ◽  
Numerical Calculations ◽  
Constant Ratio ◽  
Viscosity Coefficients ◽  
Wide Range ◽  
Minimum Film Thickness ◽  
Film Parameter ◽  
Ehl Contact

Prediction of minimum film thickness is often used in practice for calculation of film parameter to design machine operation in full film regime. It was reported several times that majority of prediction formulas cannot match experimental data in terms of minimum film thickness. These standard prediction formulas give almost constant ratio between central and minimum film thickness while numerical calculations show ratio which spans from 1 to more than 3 depending on M and L parameters. In this paper, an analytical formula of this ratio is presented for lubricants with various pressure–viscosity coefficients. The analytical formula is compared with optical interferometry measurements and differences are discussed. It allows better prediction, compared to standard formulas, of minimum film thickness for wide range of M and L parameters.

Multiphysics Modeling and Experimental Validation of Reconfigurable, E-Textile Origami Antennas

2018 ◽  
Author(s):  
Hamil Shah ◽  
Abdullahi Inshaar ◽  
Chengzhe Zou ◽  
Shreyas Chaudhari ◽  
Saad Alharbi ◽  
...  
Keyword(s):  
Antenna Arrays ◽  
Shape Change ◽  
Wave Radiation ◽  
Patch Antennas ◽  
Multiphysics Modeling ◽  
Textile Materials ◽  
New Class ◽  
Non Invasive ◽  
Radiation Properties ◽  
Wide Range

Physical deformation mechanisms are emerging as compelling and simple ways to adapt radio frequency (RF) characteristics of antennas in contrast to digital steering approaches acting on topologically fixed antennas. Concepts of physical reconfigurability also enable exceptional capabilities such as deployable and morphing antenna arrays that serve multiple functions and permit compact transport with ease. Yet, the emergent concepts lack broad understanding of effective approaches to integrate conformal, electrically conductive architectures with high-compliance foldable frameworks. To explore this essential interface where electrical demands and mechanical requirements may conflict, this research introduces a new class of origami-based tessellated antennas whose RF characteristics are self-tuned by physical reconfiguration of the antenna shape. E-textile materials are used to permit large antenna shape change while maintaining electrical conductivity. Dipole and patch antennas are considered as conventional antenna platforms upon which to innovate with the e-textile origami concept. Multiphysics modeling efforts establish the efficacy of foldable antenna geometries for broad tailoring of the RF characteristics. Experiments with proof-of-concept antennas confirm the large adaptability of wave radiation properties enabled by the reconfiguration of the e-textile origami surfaces. The results suggest that e-textile antennas can be integrated into clothing and mechanical structures, providing a non-invasive way of quantifying deformation for a wide range of applications.

The Research of GPRS-Based Remote Fault Monitoring System for CNC Machine Tools

2011 ◽  
Vol 328-330 ◽  
pp. 393-397
Author(s):  
Ming Liang Wu ◽  
Xiao Bing Wang ◽  
Shu Rong Yu
Keyword(s):  
Monitoring System ◽  
Communication Networks ◽  
Remote Monitoring ◽  
Data Transfer ◽  
High Reliability ◽  
Fast Response ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Remote Monitoring System ◽  
Wide Range

Based on GPRS network remote monitoring system which uses its two-way transmission performance, can easily monitor various electrical equipments and get information. Compare with the past remote monitoring systems, the system has the advantage of flexible networking, convenient, wide range of data transmission, high reliability, fast response time, and has great significance and value of research in CNC machine tool system with upgrade GPRS in the mobile communication networks, data services expand and data transfer capabilities.

scholarly journals Assessing land–ocean connectivity via submarine groundwater discharge (SGD) in the Ria Formosa Lagoon (Portugal): combining radon measurements and stable isotope hydrology

2016 ◽  
Vol 20 (8) ◽  
pp. 3077-3098 ◽  
Author(s):  
Carlos Rocha ◽  
Cristina Veiga-Pires ◽  
Jan Scholten ◽  
Kay Knoeller ◽  
Darren R. Gröcke ◽  
...  
Keyword(s):  
Submarine Groundwater Discharge ◽  
Large Fraction ◽  
Groundwater Discharge ◽  
Point Sources ◽  
Total N ◽  
Ria Formosa ◽  
Basin Scale ◽  
Wide Range ◽  
Dominant Feature ◽  
Submarine Groundwater

Abstract. Natural radioactive tracer-based assessments of basin-scale submarine groundwater discharge (SGD) are well developed. However, SGD takes place in different modes and the flow and discharge mechanisms involved occur over a wide range of spatial and temporal scales. Quantifying SGD while discriminating its source functions therefore remains a major challenge. However, correctly identifying both the fluid source and composition is critical. When multiple sources of the tracer of interest are present, failure to adequately discriminate between them leads to inaccurate attribution and the resulting uncertainties will affect the reliability of SGD solute loading estimates. This lack of reliability then extends to the closure of local biogeochemical budgets, confusing measures aiming to mitigate pollution.Here, we report a multi-tracer study to identify the sources of SGD, distinguish its component parts and elucidate the mechanisms of their dispersion throughout the Ria Formosa – a seasonally hypersaline lagoon in Portugal. We combine radon budgets that determine the total SGD (meteoric + recirculated seawater) in the system with stable isotopes in water (δ2H, δ18O), to specifically identify SGD source functions and characterize active hydrological pathways in the catchment. Using this approach, SGD in the Ria Formosa could be separated into two modes, a net meteoric water input and another involving no net water transfer, i.e., originating in lagoon water re-circulated through permeable sediments. The former SGD mode is present occasionally on a multi-annual timescale, while the latter is a dominant feature of the system. In the absence of meteoric SGD inputs, seawater recirculation through beach sediments occurs at a rate of  ∼  1.4  ×  106 m3 day−1. This implies that the entire tidal-averaged volume of the lagoon is filtered through local sandy sediments within 100 days ( ∼  3.5 times a year), driving an estimated nitrogen (N) load of  ∼  350 Ton N yr−1 into the system as NO3−. Land-borne SGD could add a further  ∼  61 Ton N yr−1 to the lagoon. The former source is autochthonous, continuous and responsible for a large fraction (59 %) of the estimated total N inputs into the system via non-point sources, while the latter is an occasional allochthonous source capable of driving new production in the system.

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