1,121 research outputs found
Optimization of Takeoffs on Unbalanced Fields using Takeoff Performance Tool
Unbalanced field length exists when ASDA and TODA are not equal. Airport authority may add less expensive substitutes to runway full-strength pavement in the form of stopways and/or clearways to basic TORA to increase operational takeoff weights. Here developed Takeoff Performance Tool is a physics-based total-energy model used to simulate FAR/CS 25 regulated airplane takeoffs. Any aircraft, runway, and environmental conditions can be simulated, while complying with the applicable regulations and maximizing performance takeoff weights. The mathematical model was translated into Matlab, Fortran 95/2003/2008, Basic, and MS Excel computer codes. All existing FAR/CS 25 takeoff regulations are implemented. Average forces are calculated for takeoff accelerate-go and accelerate-stop scenarios with all-engine-operating and one-engine-inoperative conditions. Special attention was paid to simulating increase in FLLTOW as the clearways and/or stopways are added in varying ratios. From the limited parametric study it appears that clearway-to-stopway ratio addition of 4:1 gives good overall performance increase while keeping decision/action speed constant. The critical clearway length exists for which both TORA and TODA are equally limiting. Corrections for effective runway slopes and wind were derived. The presented takeoff performance model provides a platform for more in-depth optimization studies and economic analysis of runway-airplane-engines synergy
Computationally Efficient Simulation of Queues: The R Package queuecomputer
Large networks of queueing systems model important real-world systems such as
MapReduce clusters, web-servers, hospitals, call centers and airport passenger
terminals. To model such systems accurately, we must infer queueing parameters
from data. Unfortunately, for many queueing networks there is no clear way to
proceed with parameter inference from data. Approximate Bayesian computation
could offer a straightforward way to infer parameters for such networks if we
could simulate data quickly enough.
We present a computationally efficient method for simulating from a very
general set of queueing networks with the R package queuecomputer. Remarkable
speedups of more than 2 orders of magnitude are observed relative to the
popular DES packages simmer and simpy. We replicate output from these packages
to validate the package.
The package is modular and integrates well with the popular R package dplyr.
Complex queueing networks with tandem, parallel and fork/join topologies can
easily be built with these two packages together. We show how to use this
package with two examples: a call center and an airport terminal.Comment: Updated for queuecomputer_0.8.
Multi-Objective Hull Form Optimization with CAD Engine-based Deep Learning Physics for 3D Flow Prediction
In this work, we propose a built-in Deep Learning Physics Optimization (DLPO)
framework to set up a shape optimization study of the Duisburg Test Case (DTC)
container vessel. We present two different applications: (1) sensitivity
analysis to detect the most promising generic basis hull shapes, and (2)
multi-objective optimization to quantify the trade-off between optimal hull
forms. DLPO framework allows for the evaluation of design iterations
automatically in an end-to-end manner. We achieved these results by coupling
Extrality's Deep Learning Physics (DLP) model to a CAD engine and an optimizer.
Our proposed DLP model is trained on full 3D volume data coming from RANS
simulations, and it can provide accurate and high-quality 3D flow predictions
in real-time, which makes it a good evaluator to perform optimization of new
container vessel designs w.r.t the hydrodynamic efficiency. In particular, it
is able to recover the forces acting on the vessel by integration on the hull
surface with a mean relative error of 3.84\% \pm 2.179\% on the total
resistance. Each iteration takes only 20 seconds, thus leading to a drastic
saving of time and engineering efforts, while delivering valuable insight into
the performance of the vessel, including RANS-like detailed flow information.
We conclude that DLPO framework is a promising tool to accelerate the ship
design process and lead to more efficient ships with better hydrodynamic
performance.Comment: X International Conference on Computational Methods in Marine
Engineering, MARINE 2023, Madrid, Spai
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