Search results for "Modeling and simulation"
showing 10 items of 1561 documents
Interactive multiobjective optimization system WWW-NIMBUS on the Internet
2000
Abstract NIMBUS is a multiobjective optimization method capable of solving nondifferentiable and nonconvex problems. We describe the NIMBUS algorithm and its implementation WWW-NIMBUS. To our knowledge WWW-NIMBUS is the first interactive multiobjective optimization system on the Internet. The main principles of its implementation are centralized computing and a distributed interface. Typically, the delivery and update of any software is problematic. Limited computer capacity may also be a problem. Via the Internet, there is only one version of the software to be updated and any client computer has the capabilities of a server computer. Further, the World-Wide Web (WWW) provides a graphical …
Guaranteed lower bounds for cost functionals of time-periodic parabolic optimization problems
2019
In this paper, a new technique is shown for deriving computable, guaranteed lower bounds of functional type (minorants) for two different cost functionals subject to a parabolic time-periodic boundary value problem. Together with previous results on upper bounds (majorants) for one of the cost functionals, both minorants and majorants lead to two-sided estimates of functional type for the optimal control problem. Both upper and lower bounds are derived for the second new cost functional subject to the same parabolic PDE-constraints, but where the target is a desired gradient. The time-periodic optimal control problems are discretized by the multiharmonic finite element method leading to lar…
Multiple-criteria cash-management policies with particular liquidity terms
2019
Abstract Eliciting policies for cash management systems with multiple assets is by no means straightforward. Both the particular relationship between alternative assets and time delays from control decisions to availability of cash introduce additional difficulties. Here we propose a cash management model to derive short-term finance policies when considering multiple assets with different expected returns and particular liquidity terms for each alternative asset. In order to deal with the inherent uncertainty about the near future introduced by cash flows, we use forecasts as a key input to the model. We express uncertainty as lack of predictive accuracy and we derive a deterministic equiv…
A multi-technique simultaneous approach for the design of a sailing yacht
2015
In this paper, most significant steps involved during the whole process of designing a sailing yacht are outlined. In particular, a novel simultaneous approach has been proposed to optimize the design process of a sailing yacht. Analytical resistance prediction models are simultaneously used with CAD systems and computational fluid dynamics tools to find, in the more effective way, the best solution for the chosen design conditions. As a general rule, in fact, once the target point has been decided, task of the designer is the definition of those systems of aerodynamic and hydrodynamic forces that are in equilibrium when the boat sails at its target. Unfortunately, a multi-purpose yacht doe…
Integer programming models for the pre-marshalling problem
2019
[EN] The performance of shipping companies greatly depends on reduced berthing times. The trend towards bigger ships and shorter berthing times places severe stress on container terminals, which cannot simply increase the available cranes indefinitely. Therefore, the focus is on optimizing existing resources. An effective way of speeding up the loading/unloading operations of ships at the container terminal is to use the idle time before the arrival of a ship for sorting the stored containers in advance. The pre-marshalling problem consists in rearranging the containers placed in a bay in the order in which they will be required later, looking for a sequence with the minimum number of moves…
Customised pressure profiles of made-to-measure sports compression garments
2021
AbstractThe purpose of this study was to make made-to-measure compression garments that elicit pressures within and below clinical standards. The study also examined whether pressures and gradients can be replicated within and between participants’ legs, and between separate compression garment conditions. Ten males volunteered to participate. Based on three-dimensional scans of the participants’ lower body, three different made-to-measure garments were manufactured: control, symmetrical and asymmetrical. Garment pressures were assessed from the malleolus to the gluteal fold using a pressure monitoring device. A root mean squared difference analysis was used to calculate the in vivo linear …
Recent Advances in Static Output-Feedback Controller Design with Applications to Vibration Control of Large Structures
2014
Published version of an article in the journal: Modeling, Identification and Control. Also available from the publisher at: http://dx.doi.org/10.4173/mic.2014.3.4 Open Access In this paper, we present a novel two-step strategy for static output-feedback controller design. In the first step, an optimal state-feedback controller is obtained by means of a linear matrix inequality (LMI) formulation. In the second step, a transformation of the LMI variables is used to derive a suitable LMI formulation for the static output-feedback controller. This design strategy can be applied to a wide range of practical problems, including vibration control of large structures, control of oshore wind turbine…
Fitting random cash management models to data
2019
Abstract Organizations use cash management models to control balances to both avoid overdrafts and obtain a profit from short-term investments. Most management models are based on control bounds which are derived from the assumption of a particular cash flow probability distribution. In this paper, we relax this strong assumption to fit cash management models to data by means of stochastic and linear programming. We also introduce ensembles of random cash management models which are built by randomly selecting a subsequence of the original cash flow data set. We illustrate our approach by means of a real case study showing that a small random sample of data is enough to fit sufficiently goo…
Suitability Of Cellular Network Signaling Data For Origin-Destination Matrix Construction: A Case Study Of Lyon Region (France)
2019
TRB 2019, 98th Annual Meeting Transportation Research Board, Washigton, D.C., ETATS-UNIS, 13-/01/2019 - 17/01/2019; Spatiotemporal data, and more specifically origin-destination matrices, are critical inputs to mobility studies for transportation planning and urban management purposes. In this paper, we propose a methodology to infer origin-destination (O-D) matrices based on passively-collected cellular signaling data of millions of anonymized mobile phone users in the Rhône-Alpes region, France. This dataset, which consists of records time-stamped with users' unique identifier and tower locations, is used to first analyze the cell phone activity degree indicators of each user in orde…
On universality of critical behavior in the focusing nonlinear Schrödinger equation, elliptic umbilic catastrophe and the Tritronquée solution to the…
2008
We argue that the critical behavior near the point of “gradient catastrophe” of the solution to the Cauchy problem for the focusing nonlinear Schrodinger equation \(i\epsilon \varPsi _{t}+\frac{\epsilon^{2}}{2}\varPsi _{xx}+|\varPsi |^{2}\varPsi =0\) , e ≪1, with analytic initial data of the form \(\varPsi (x,0;\epsilon)=A(x)e^{\frac{i}{\epsilon}S(x)}\) is approximately described by a particular solution to the Painleve-I equation.