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News Article | May 25, 2017
Site: www.sciencedaily.com

Researchers from Universidad Politécnica de Madrid (UPM), Universidad Rey Juan Carlos (URJC) and Massachusetts Institute of Technology (MIT) have developed a model to optimize the decision making of airlines against their competitors. A team of researchers from two Spanish universities, UPM and URJC, in collaboration with MIT researchers has developed a mathematical model that assesses the competition between airlines, both legacy and low-cost airlines, and high-speed trains. This new approach is able to estimate the modal distribution of passenger demand, optimize fleet assignment and generate flight schedule. This math tool provides valuable and useful information that will help airlines to efficiently face the competition of high-speed trains. Airlines and high-speed trains are increasingly competing for passengers, especially in Europe and Asia. High-speed trains usually compete by providing similar or even greater service frequency and better connectivity to city centers. Besides, HST is often perceived as the safer and more comfortable mode, this situation generates a redistribution of passengers between aerial and railway alternatives. Thus, a group of researchers, including the Professor Ángel Martín from School of Aeronautics and Space Engineering, gathered to study the impact of the uncertainty on regular aerial transport. In this way, researchers have developed a competition model −considering the multimodal competition between aerial transport and high-speed trains and the aerial competition between legacy companies and low-cost companies− that uses a nested logit model that captures the impacts of the decisions taken by aerial companies on passenger demand. At the core of this modeling approach is an integrated schedule optimization model that includes frequency planning, approximate timetable development, fleet assignment, and passenger demand choice. The computational results were carried out on realistic problem instances of the Spanish airline IBERIA and show that the actual airline schedules are found to be reasonably close to the schedules generated by our approach. Researchers also used this optimization modeling approach under multimodal competition to evaluate multiple scenarios involving entry of high speed rail into new markets, taking into account the possibility of demand stimulation as a result of the new services. This model was validated by using data from markets that had an entry by high speed rail in the past. The validation results show a close match between the predicted and the observed solutions. In addition this model can predict the impacts of future entry by high speed rail on new markets. Consequently, the proposed modeling framework is attractive from the perspective of the airline operators. It allows them to plan better for the impending HST entry by fine-tuning schedules, fleets, and fares. According to Ángel Martín, a researcher involved in this study, "The framework can facilitate careful evaluation of various scenarios (such as competitor actions, fleet changes, fare changes, etc.) allowing the airline to be better prepared to adapt to the changing competitive environment." This research was carried out within the framework of the project "Robustness, efficiency and recovery of public transport systems," TRA2014-52530-C3-1-P research project of Ministry of Economy and Competitiveness.


De Mera Sanchez P.D.,URJC | Gaya C.G.,Spanish University for Distance Education (UNED) | Perez M.A.S.,Spanish University for Distance Education (UNED)
Procedia Engineering | Year: 2013

Excellence in design is an important differentiating factor between competing products; establishing a key pillar for companies face up with safety the challenges ahead in global markets. The implementation of process management, in turn, has emerged as one of the tools for improving management more effective and its application to design product powering growth vectors, such as innovation and productivity. A project level, the management model of the design process for products manufactured according to BS 7000-2: 2008 can be compared with the models predictive of project management, mainly international PMBOK ® guide and the model developed in Europe, PRINCE2. Potential similarities to be established in comparison shall take into account an integrated vision focus on all levels according to processes as initiation, planning, implementation, monitoring and controlling, and closing. © 2013 The Authors.


de Mera Sanchez P.D.,URJC | Gaya C.G.,Spanish University for Distance Education (UNED) | Prieto V.F.R.,Spanish University for Distance Education (UNED) | Camprubi F.M.,Spanish University for Distance Education (UNED)
Materials Science Forum | Year: 2014

A key factor to enhance industrial competitiveness is to develop strategies around product design, applying the concept of excellence in all its stages and emphasizing innovation efforts. The process of product design as an important element in the differentiation between competing products needs to lean on effective tools that help to meet the demands of customers in the global competitive markets. In response to this need it arises, the European regulatory paradigm on the design of products, standard BS 7000-2: 2008 [1]. It is worth analyzing the influence on the design of manufactured products of the processes of project management of predictive models used mainly. The processes described in each of the models covered along with those reflected in the aforementioned regulations will provide guidance on any differences or similarities in the various phases at project level. © (2014) Trans Tech Publications, Switzerland.


Rodriguez Aguilera A.,University of Granada | Leon Salas A.,University of Granada | Martin Perandres D.,University of Granada | Otaduy M.A.,URJC
Computers and Graphics (Pergamon) | Year: 2015

In this work, we propose a method to interactively deform high-resolution volumetric datasets, such as those obtained through medical imaging. Interactive deformation enables the visualization of these datasets in full detail using state-of-the-art volume rendering techniques as they are dynamically modified. Our approach relies on resampling the original dataset to a target regular grid, following a 3D rasterization technique. We employ an implicit auxiliary mesh to execute resampling, which allows us to decouple mapping of the deformation field to the volume from actual resampling. In this way, our method is practically independent of the deformation method of choice, as well as of the resolution of the deformation meshes. We show how our method lends itself nicely to an efficient, massively parallel implementation on GPUS, and we demonstrate its application on several high-resolution datasets and deformation models. © 2015 Elsevier Ltd. All rights reserved.


Soler M.,URJC | Kamgarpour M.,ETH Zurich | Tomlin C.,University of California at Berkeley | Staffetti E.,URJC
Proceedings of the IEEE Conference on Decision and Control | Year: 2012

This paper formulates the problem of aircraft conflict avoidance as a multiphase mixed-integer optimal control problem. In order to find optimal maneuvers, accurate models of aircraft nonlinear dynamics and flight envelop constraints are used. Wind forecast and obstacles in airspace due to hazardous weather are included. The objective is to design aircraft maneuvers that ensure safety while minimizing fuel consumption. The solution approach is based on conversion of the multiphase mixed-integer optimal control problem into a mixed-integer nonlinear programming problem. Two case studies for the Airbus 320 aircraft illustrate the approach. © 2012 IEEE.


Kamgarpour M.,University of California at Berkeley | Soler M.,URJC | Tomlin C.J.,University of California at Berkeley | Olivares A.,URJC | Lygeros J.,ETH Zurich
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2011

The problem of aircraft trajectory planning is formulated as a hybrid optimal control problem. The aircraft is modeled as a switched system, that is, a class of hybrid dynamical systems. The sequence of modes, the switching times, and the inputs for each mode are the control variables. An iterative bi-level optimization algorithm is employed to solve the optimal control problem. At the lower level, given a pre-defined sequence of flight modes, the optimal switching times and the input for each mode are determined. This is achieved by extending the continuous state to include the switching times and then solving a conventional optimal control problem for the extended state. At the higher level, the algorithm modifies the mode sequence in order to decrease the value of the cost function. We illustrate the utility of the problem formulation and the solution approach with two case studies in which short horizon aircraft trajectories are optimized in order to reduce fuel burn while avoiding hazardous weather. © 2011 IFAC.


Rubio-Sanchez M.,URJC | Raya L.,U tad | Diaz F.,Technical University of Madrid | Sanchez A.,URJC
IEEE Transactions on Visualization and Computer Graphics | Year: 2016

RadViz and star coordinates are two of the most popular projection-based multivariate visualization techniques that arrange variables in radial layouts. Formally, the main difference between them consists of a nonlinear normalization step inherent in RadViz. In this paper we show that, although RadViz can be useful when analyzing sparse data, in general this design choice limits its applicability and introduces several drawbacks for exploratory data analysis. In particular, we observe that the normalization step introduces nonlinear distortions, can encumber outlier detection, prevents associating the plots with useful linear mappings, and impedes estimating original data attributes accurately. In addition, users have greater flexibility when choosing different layouts and views of the data in star coordinates. Therefore, we suggest that analysts and researchers should carefully consider whether RadViz's normalization step is beneficial regarding the data sets' characteristics and analysis tasks. © 1995-2012 IEEE.


Cirio G.,French Institute for Research in Computer Science and Automation | Marchal M.,French Institute for Research in Computer Science and Automation | Otaduy M.A.,URJC | Lecuyer A.,French Institute for Research in Computer Science and Automation
2013 World Haptics Conference, WHC 2013 | Year: 2013

Haptic interaction with different types of materials in the same scene is a challenging task, mainly due to the specific coupling mechanisms that are usually required for either fluid, deformable or rigid media. Dynamically-changing materials, such as melting or freezing objects, present additional challenges by adding another layer of complexity in the interaction between the scene and the haptic proxy. In this paper, we address these issues through a common simulation framework, based on Smoothed-Particle Hydrody-namics, and enable haptic interaction simultaneously with fluid, elastic and rigid bodies, as well as their melting or freezing. We introduce a mechanism to deal with state changes, allowing the perception of haptic feedback during the process, and a set of dynamic mechanisms to enrich the interaction through the proxy. We decouple the haptic and visual loops through a dual GPU implementation. An initial evaluation of the approach is performed through performance and feedback measurements, as well as a small user study assessing the capability of users to recognize the different states of matter they interact with. © 2013 IEEE.


Olivares A.,URJC | Soler M.,URJC | Staffetti E.,URJC
ACM International Conference Proceeding Series | Year: 2013

In this paper an approach to aircraft trajectory optimization is presented in which integer variables and continuous variables are considered. Integer variables model decision making processes, and continuous variables describe the state of the aircraft which evolves according to differentialalgebraic equations. The problem is formulated as a multiphase mixed-integer optimal control problem. It is transcribed into a mixed integer nonlinear programming problem by applying a 5th degree Gauss-Lobatto direct collocation method and then solved using a nonlinear programming based branch-and-bound algorithm. The approach is applied to the following en-route flight planning problem: given an aircraft point mass model, a wind forecast, a 3D airspace structure, and the relevant flying information regions with their associated overflying costs, find the control inputs that steer the aircraft from the initial fix to the final fix following a route of waypoints and performing step climbs, while minimizing certain performance indexes in which fuel based, environmental based, time based, and overflying based costs are considered during the flight. The decision making process arises in determining the optimal sequence of waypoints and the optimal sequence of flight levels. The optimal times at which the step climbs are performed and the waypoints are to be overflown are also to be determined. Numerical results are presented and discussed, showing the effectiveness of the approach.


Rubio-Sanchez M.,URJC | Sanchez A.,URJC
IEEE Transactions on Visualization and Computer Graphics | Year: 2014

Star coordinates is a well-known multivariate visualization method that produces linear dimensionality reduction mappings through a set of radial axes defined by vectors in an observable space. One of its main drawbacks concerns the difficulty to recover attributes of data samples accurately, which typically lie in the [0], [1] interval, given the locations of the low-dimensional embeddings and the vectors. In this paper we show that centering the data can considerably increase attribute estimation accuracy, where data values can be read off approximately by projecting embedded points onto calibrated (i.e., labeled) axes, similarly to classical statistical biplots. In addition, this idea can be coupled with a recently developed orthonormalization process on the axis vectors that prevents unnecessary distortions. We demonstrate that the combination of both approaches not only enhances the estimates, but also provides more faithful representations of the data. © 1995-2012 IEEE.

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