715 research outputs found
Using artificial neural networks and strain gauges for the determination of static loads on a thin square fully constrained composite marine panel subjected to a large central displacement
Current methods of estimating the behaviour of marine composite structures under pressure due to slamming as a result of high waves are based on trial and error or oversimplification. Normally under these conditions the nonlinearities of these structures are often neglected and in order to compensate, an overestimated safety factor is employed. These conservative approaches can result in heavier and overdesigned structures. In this paper a new semi-empirical method is proposed that overcomes some of these problems. This work involved the use of Artificial Neural Network (ANN) combined with strain gauge data to enable real-time in-service load monitoring of large marine structural panels. Such a tool has other important applications such as monitoring slamming or other transient hydrostatic loads that can ultimately affect their fatigue life. To develop this system a Glass Fibre Reinforced Polymer (GFRP) composite panel was used due to its potential for providing a nonlinear response to pressure or slamming loads. It was found the ANN was able to predict normal loads applied at different locations on the panel accurately. This method is also capable of predicting loads on the marine structure in real-time
Load measurement of in-service marine structures to influence their design.
Current methods to predict hydrodynamic loads rely either on oversimplified and semiempirical methods or the use of numerical simulation and analysis techniques such as Finite Element Analysis (FEA) or Boundary Element Analysis (BEA). These methods are conservative which results in the over-design of these craft so they are heavier and slower than they could otherwise be. Better understanding of load intensities will inform the design process of marine structures and could result in lighter and more efficient designs. This research investigates the possibility of solving these problems employing artificial intelligence (AI) as an alternative to the current methods. Few studies have applied Artificial Intelligence to the design of marine structures. Detailed review of the past and present research shows that AI and in particular Artificial Neural Networks (ANN) can be used as an inverse problem solver when there are no closed form relationships that exist between the input and the output. An inverse approach is defined as the problem where response of the structure is known but the load that caused that response is unknown. In real problems/structures the response to a point load is experienced throughout the structure with different levels of intensities which is the link between the external load and these differential intensities. Determining this relationship will result in a unique solution without the knowledge of material constitutive laws, material properties and structure size or thickness. The aim of this investigation is to develop a real time in-service load measurement tool using an inverse approach. To achieve this, ANN, experimental techniques and FEA analysis are combined to form a hybrid inverse problem solver that can be trained to use structural response, such as strains at various locations, to predict the loads that caused them. The main objective of this research is to investigate the suitability of the proposed methodology for real time in-service load monitoring on large marine structures. The proposed system must be able to measure both steady-state as well as transient load such as equivalent slamming load. The outcome of this investigation was successful prediction of the external loads in terms of their approximate location and load intensities. The only disadvantage of this method is that the solver requires training and can only learn from cases that it has been subjected to. However, once the system is trained it can predict both static and dynamic loads quickly and accurately
Investigation on the Essential Oils of the Achillea Species: From Chemical Analysis to the In Silico Uptake against SARS-CoV-2 Main Protease
In this study, phytochemicals extracted from three different Achillea genera were identified and analyzed to be screened for their interactions with the SARS-CoV-2 main protease. In particular, the antiviral potential of these natural products against the SARS-CoV-2 main protease was investigated, as was their effectiveness against the SARS-CoV-1 main protease as a standard (due to its high similarity with SARS-CoV-2). These enzymes play key roles in the proliferation of viral strains in the human cytological domain. GC-MS analysis was used to identify the essential oils of the Achillea species. Chemi-informatics tools, such as AutoDock 4.2.6, SwissADME, ProTox-II, and LigPlot, were used to investigate the action of the pharmacoactive compounds against the main proteases of SARS-CoV-1 and SARS-CoV-2. Based on the binding energies of kessanyl acetate, chavibetol (m-eugenol), farnesol, and 7-epi-beta-eudesmol were localized at the active site of the coronaviruses. Furthermore, these molecules, through hydrogen bonding with the amino acid residues of the active sites of viral proteins, were found to block the progression of SARS-CoV-2. Screening and computer analysis provided us with the opportunity to consider these molecules for further preclinical studies. Furthermore, considering their low toxicity, the data may pave the way for new in vitro and in vivo research on these natural inhibitors of the main SARS-CoV-2 protease
Morgan-Morgan-NUT disk space via the Ehlers transformation
Using the Ehlers transformation along with the gravitoelectromagnetic
approach to stationary spacetimes we start from the Morgan-Morgan disk
spacetime (without radial pressure) as the seed metric and find its
corresponding stationary spacetime. As expected from the Ehlers transformation
the stationary spacetime obtained suffers from a NUT-type singularity and the
new parameter introduced in the stationary case could be interpreted as the
gravitomagnetic monopole charge (or the NUT factor). As a consequence of this
singularity there are closed timelike curves (CTCs) in the singular region of
the spacetime. Some of the properties of this spacetime including its particle
velocity distribution, gravitational redshift, stability and energy conditions
are discussed.Comment: 18 pages, 5 figures, RevTex 4, replaced with the published versio
A significant hardening and rising shape detected in the MeV/GeV nuFnu spectrum from the recently-discovered very-high-energy blazar S4 0954+65 during the bright optical flare in 2015 February
We report on Fermi Large Area Telescope (LAT) and multi-wavelength results on
the recently-discovered very-high-energy (VHE, 100 GeV) blazar S4 0954+65
() during an exceptionally bright optical flare in 2015 February.
During the time period (2015 February, 13/14, or MJD 57067) when the MAGIC
telescope detected VHE -ray emission from the source, the Fermi-LAT
data indicated a significant spectral hardening at GeV energies, with a
power-law photon index of ---compared with the 3FGL value
(averaged over four years of observation) of . In contrast,
Swift/XRT data showed a softening of the X-ray spectrum, with a photon index of
(compared with averaged during the flare from
MJD 57066 to 57077), possibly indicating a modest contribution of synchrotron
photons by the highest-energy electrons superposed on the inverse Compton
component. Fitting of the quasi-simultaneous ( day) broadband spectrum with
a one-zone synchrotron plus inverse-Compton model revealed that GeV/TeV
emission could be produced by inverse-Compton scattering of external photons
from the dust torus. We emphasize that a flaring blazar showing high flux of
photons cm s ( 100 MeV) and a
hard spectral index of detected by Fermi-LAT on daily
time scales is a promising target for TeV follow-up by ground-based Cherenkov
telescopes to discover high-redshift blazars, investigate their temporal
variability and spectral features in the VHE band, and also constrain the
intensity of the extragalactic background light.Comment: 15 pages, 3 figures, 2 tables. Accepted by PAS
Investigation of the quasi-free domain in deuteron-deuteron break-up using spin observables
Precision measurements of vector and tensor analyzing powers of the 2H(d, dp)n break-up process
for configurations in the vicinity of the quasi-free scattering regime with the neutron as spectator
are presented. These measurements are performed with a polarized deuteron-beam with an energy of
65MeV/nucleon impinging on a liquid-deuterium target. The experiment was conducted at the AGOR
facility at KVI using the BINA 4Ï€-detection system. Events for which the final-state deuteron and proton
are coplanar have been analyzed and the data have been sorted for various momenta of the missing
neutron. In the limit of vanishing neutron momentum and at large deuteron-proton momentum transfer,
the data agree well with the measured and theoretically predicted spin observables of the elastic deuteronproton
scattering process. The agreement deteriorates rapidly with increasing neutron momentum and/or
decreasing momentum transfer from the deuteron beam to the outgoing proton. This study reveals the
presence of a significant contribution of final-state interactions even at very small neutron momenta
Measurements of scattering observables for the break-up reaction
High-precision measurements of the scattering observables such as cross
sections and analyzing powers for the proton-deuteron elastic and break-up
reactions have been performed at KVI in the last two decades and elsewhere to
investigate various aspects of the three-nucleon force (3NF) effects
simultaneously. In 2006 an experiment was performed to study these effects in
break-up reaction at 135 MeV with the detection system, Big
Instrument for Nuclear polarization Analysis, BINA. BINA covers almost the
entire kinematical phase space of the break-up reaction. The results are
interpreted with the help of state-of-the-art Faddeev calculations and are
partly presented in this contribution.Comment: Proceedings of 19th International IUPAP Conference on Few-Body
Problems in Physics, Bonn University, 31.08 - 05.09.2009, Bonn, GERMAN
Comprehensive measurements of cross sections and spin observables of the three-body break-up channel in deuteron-deuteron scattering at 65 MeV/nucleon
Detailed measurements of five-fold differential cross sections and a rich set
of vector and tensor analyzing powers of the 2H(d; dp)n break-up process using
polarized deuteron-beam energy of 65 MeV/nucleon with a liquid-deuterium target
are presented. The experiment was conducted at the AGOR facility at KVI using
the BINA 4Pi-detection system. We discuss the analysis procedure including a
thorough study of the systematic uncertainties. The results can be used to
examine upcoming state-of-the-art calculations in the four-nucleon scattering
domain, and will, thereby, provide further insights into the dynamics of three-
and four-nucleon forces in few-nucleon systems. The results of coplanar
configurations are compared with the results of recent theoretical calculations
based on the Single-Scattering Approximation (SSA). Through these comparisons,
the validity of SSA approximation is investigated in the Quasi-Free (QF)
region.Comment: 33 pages, 30 figure
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