scholarly journals Exploring the Time Domain with Synoptic Sky Surveys

2011 ◽  
Vol 7 (S285) ◽  
pp. 141-146 ◽  
Author(s):  
S. G. Djorgovski ◽  
A. A. Mahabal ◽  
A. J. Drake ◽  
M. J. Graham ◽  
C. Donalek ◽  
...  
Keyword(s):  
Time Domain ◽  
Lessons Learned ◽  
Sky Surveys ◽  
The Past ◽  
Systematic Exploration ◽  
The Time Domain ◽  
New Research

AbstractSynoptic sky surveys are becoming the largest data generators in astronomy, and they are opening a new research frontier that touches practically every field of astronomy. Opening the time domain to a systematic exploration will strengthen our understanding of a number of interesting known phenomena, and may lead to the discoveries of as yet unknown ones. We describe some lessons learned over the past decade, and offer some ideas that may guide strategic considerations in the planning and execution of future synoptic sky surveys.

Stability Evaluations of Semi-Submersible Heavy Transport Vessels by a Progressive Flooding Simulation Tool

2012 ◽  
Author(s):  
Hendrik Dankowski ◽  
Hannes Hatecke
Keyword(s):  
Time Domain ◽  
Simulation Method ◽  
Intermediate Step ◽  
Viscous Effects ◽  
The Past ◽  
Discharge Coefficients ◽  
Damage Stability ◽  
Offshore Industry ◽  
The Stability ◽  
The Time Domain

Rising needs for heavy transport operations are intensified by the expanding offshore industry worldwide. Whenever very large and heavy objects have to be transported, only semi-submersible heavy transport vessels are capable of carrying this special cargo. Accidents in the past during operations of these vessels highlight the requirement of analyzing the operation procedures in more detail. Especially the submerging process of the main working deck is very critical regarding the hydrostatic stability. A new numerical progressive flooding simulation method will be presented for applications like accident investigations or damage stability assessments. This method is modified to fit the special requirements of simulating the operational behavior of semi-submersible vessels in the time-domain. A direct approach is chosen, which computes the flux between the compartments based on the Bernoulli equation and the current pressure heads at each intermediate step. Losses due to viscous effects are taken into account by empirical discharge coefficients. This method will be used to simulate the submerging operation in the time-domain to point out critical situations regarding the stability of the vessels and the cargo. This will be compared to accidents which occurred in the past. Furthermore, recommendations for operational procedures are proposed.

scholarly journals The VAO Transient Facility

2011 ◽  
Vol 7 (S285) ◽  
pp. 318-320
Author(s):  
Matthew J. Graham ◽  
S. G. Djorgovski ◽  
Andrew Drake ◽  
Ashish Mahabal ◽  
Roy Williams ◽  
...  
Keyword(s):  
Machine Learning ◽  
Quality Of Service ◽  
Time Domain ◽  
Astronomical Observatory ◽  
Sky Surveys ◽  
Prior Art ◽  
Event Notification ◽  
The Time Domain ◽  
Time Critical

AbstractThe time-domain community wants robust and reliable tools to enable the production of, and subscription to, community-endorsed event notification packets (VOEvent). The Virtual Astronomical Observatory (VAO) Transient Facility (VTF) is being designed to be the premier brokering service for the community, both collecting and disseminating observations about time-critical astronomical transients but also supporting annotations and the application of intelligent machine-learning to those observations. Two types of activity associated with the facility can therefore be distinguished: core infrastructure, and user services. We review the prior art in both areas, and describe the planned capabilities of the VTF. In particular, we focus on scalability and quality-of-service issues required by the next generation of sky surveys such as LSST and SKA.

scholarly journals DYNAMICS OF AN ELASTIC AIRPLANE

Aviation ◽  
2005 ◽  
Vol 9 (1) ◽  
pp. 8-13
Author(s):  
Peter Chudý ◽  
Vladimír Daněk
Keyword(s):  
Numerical Simulation ◽  
Analytical Solution ◽  
Time Domain ◽  
Aerospace Engineering ◽  
Elastic Response ◽  
Elastic Model ◽  
The Past ◽  
University Of Technology ◽  
Complex Simulation ◽  
The Time Domain

This paper presents the work performed by the Institute of Aerospace Engineering at the Brno University of Technology. The purpose of the project was to compare the results obtained from classical analytical solutions and a complex numerical simulation of an airplane's aero elastic response. Compared to the analytical solution, which reduces the entire process to a straightforward manipulation with time‐proven graphs and tables, the numerical simulation offers a more complex description of the dynamic processes. A complex simulation, in contrast to the analytical solution providing us with only one estimated parameter, allows monitoring selected quantities in the time domain, thus giving us a tool for a visual qualification of the investigated process. In the past, dynamic aeroelastic properties were estimated utilizing simplified stick beam models. The desire for more complex aero elastic simulations led to the concept of the advanced aero elastic model, coupling advanced 3D structural FEM models with proven aerodynamic theory in the form of the DLM panel method.

Stellar Variability: from Citizen Science to Citizen Astronomy

2017 ◽  
Vol 14 (S339) ◽  
pp. 215-219
Author(s):  
S. Kafka ◽  
E. Griffin
Keyword(s):  
Citizen Science ◽  
Time Domain ◽  
Public Understanding Of Science ◽  
Public Understanding ◽  
Active Engagement ◽  
Sky Surveys ◽  
The Public ◽  
Science Projects ◽  
Understanding Of Science ◽  
The Time Domain

AbstractThe contribution of citizens to research is irrefutable. Especially this century with the outburst of all-sky surveys, professional astronomers use citizen-science projects to engage the public in analysing and sorting large quantities of data, often leading to noteworthy discoveries. From crowdsourcing to acquiring data, citizens are leaving a significant mark in the science landscape, assisting professional astronomers with their work. In turn, citizen science is a means of increasing science literacy and public understanding of science. At the same time, the time domain enables a more active engagement of backyard observers in research. Citizen astronomers not only take data, but also reduce and analyse them, and participate in preparing scientific manuscripts.

scholarly journals The Method of Lines in the time domain

2013 ◽  
Vol 11 ◽  
pp. 15-21
Author(s):  
S. F. Helfert
Keyword(s):  
Time Domain ◽  
Initial Value Problems ◽  
Method Of Lines ◽  
Initial Value ◽  
One Dimensional ◽  
The Past ◽  
Left Handed ◽  
The Method Of Lines ◽  
Homogeneous Structures ◽  
The Time Domain

Abstract. The Method of Lines (MoL) is a semi-analytical numerical algorithm that has been used in the past to solve Maxwell's equations for waveguide problems. It is mainly used in the frequency domain. In this paper it is shown how the MoL can be used to solve initial value problems in the time domain. The required expressions are derived for one-dimensional structures, where the materials may be dispersive. The algorithm is verified with numerical results for homogeneous structures, and for the concatenation of standard dielectric and left handed materials.

Lessons Learned From Matching Experimental Data to Low-Order Models of Vehicle Behavior

2007 ◽  
Author(s):  
Sean N. Brennan ◽  
Bridget C. Hamblin
Keyword(s):  
Experimental Data ◽  
Lessons Learned ◽  
Roll Angle ◽  
Tire Model ◽  
Work Related ◽  
Terrain Effects ◽  
The Time Domain ◽  
New Research ◽  
Vehicle Chassis ◽  
Low Order

This work presents “lessons learned” from an ongoing experimental and simulation investigation of vehicle chassis dynamics. The overall goal of this work is to find low-order physics-based models that are easily fitted from experimental data, yet accurately describe vehicle chassis motion in yaw, sideslip, and roll angle. In previous work related to this effort [5], anomalies in the model were found where key tire parameters, specifically the cornering stiffnesses, exhibit different best-fit values depending on whether the vehicle is tested in swept sine frequency responses or curvilinear steadystate motion such as skid pad maneuvers. The first portion of this work summarizes these results. Next, new research is presented investigating the source of cornering stiffness discrepancies. The tire modeling errors are found to be very strongly related to vehicle roll angle, and from this insight, corrections to the simple chassis models are derived to allow inclusion of a roll dependency in the tire model. Additionally, during investigation of this advanced tire model, terrain disturbances were found to be significant. A method to remove terrain effects is proposed and demonstrated. Comparing these roll- and terrain-corrected fits to results from prior work [5], the new model gives a significantly improved fit in the frequency domain, and outstanding fit in the time domain.

Time Domain Simulations of Side-by-Side Moored Vessels: Lessons Learnt From a Benchmark Test

2007 ◽  
Author(s):  
Mamoun Naciri ◽  
Olaf Waals ◽  
Jaap de Wilde
Keyword(s):  
Time Domain ◽  
Wind Waves ◽  
Lessons Learned ◽  
Benchmark Test ◽  
Availability Analysis ◽  
Benchmark Study ◽  
Lessons Learnt ◽  
The Time Domain

Time domain simulations are used extensively to assess the availability of turret moored terminals for offloading operations. The availability analysis provides a key input when assessing the economical viability of a project. In this context, it was deemed important to perform a benchmark study. Three programs have been used: AQWA-DRIFT - an ANSYS product maintained by Century Dynamics and used at SBM, LIFSIM and aNySIM both developed in MARIN. Five environments including wind, waves and current have been selected one of which with all components in-line and the remaining four with oblique wind and current. Simulations have been performed with identical input for the three programs. Results are compared statistically, but also in the time domain. Lessons learned will be discussed and areas of improvement identified.

Apodisation in the time domain

1992 ◽  
Vol 2 (4) ◽  
pp. 615-620
Author(s):  
G. W. Series
Keyword(s):  
Time Domain ◽  
The Time Domain

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

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