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Tangible Interaction and Industrial Degrowth: Follow-up of a panel on environmental issues in tangible interfaces at ETIS 2022.
No full textHCI4ClimateChange workshop at CHI 2023International audienceThis position paper seeks to ground and outline a discussion on environmental issues related to tangible user interfaces. The discussion that we present here started during a panel on "Tangible Interaction and Industrial Degrowth" that took place during the ETIS European studio on tangible interaction in November 2022 [5]. The panel discussed the problem from various angles and took input from the participants of the studio in the form of an online mapping brainstorm. The topics covered ranged from environmental feedback aspects to low-tech alternatives, as well as systemic, methodological and regulation considerations. This position paper reports on the approaches that were discussed and, based on these first insights, suggests directions for sustainable tangible interaction
A Machine Learned Traffic Flow Coordination Framework for Flow-Centric Airspace
No full textInternational audienceAir traffic flow coordination at major flow intersections is a key enabler for flow-centric airspace concepts. This paper develops a flow-centric air traffic flow coordination framework to improve air traffic flow efficiency through flow identification, prediction, and rerouting at the Nominal Flow Intersections (NFIs). To identify the NFIs, a graph-based flow pattern consistency approach is proposed to model and analyze daily air traffic flow patterns. To predict future traffic demands at the identified NFIs, a transformer encoder-based neural network is adopted to learn the relations among the flow of flights at the NFIs. The acceptable flow limits at the NFIs are then determined by phase transitions of the flow efficiency versus the traffic demand. Finally, to avoid the predicted demand exceeding the identified flow limit and improve the flow efficiency, a reinforcement learning-based flow rerouting agent is trained to dynamically assign alternative routes to air traffic flows based on the evolving flow states. The agent's performance is quantified by the flight time reduction in the flows without exceeding the flow limits. The rerouting model is trained and tested on a busy NFI that handles cross-border flows between Bordeaux and Madrid/Barcelona control centers, using ADS-B data for Dec 2019 in European airspace. Results show that, compared with the originally planned flows, the travel time of each flight is reduced by 322.168 seconds on average on a 2-hour basis
Changes in plant diversity and vegetation structure based on REVEALS reconstructed vegetation of Europe during the Holocene
No full textInternational audienc
How Hard is Asynchronous Weight Reassignment? (Extended Version)
No full textInternational audienceThe performance of distributed storage systems deployed on wide-area networks can be improved using weighted (majority) quorum systems instead of their regular variants due to the heterogeneous performance of the nodes. A significant limitation of weighted majority quorum systems lies in their dependence on static weights, which are inappropriate for systems subject to the dynamic nature of networked environments. To overcome this limitation, such quorum systems require mechanisms for reassigning weights over time according to the performance variations. We study the problem of node weight reassignment in asynchronous systems with a static set of servers and static fault threshold. We prove that solving such a problem is as hard as solving consensus, i.e., it cannot be implemented in asynchronous failure-prone distributed systems. This result is somewhat counter-intuitive, given the recent results showing that two related problems -- replica set reconfiguration and asset transfer -- can be solved in asynchronous systems.Inspired by these problems, we present two versions of the problem that contain restrictions on the weights of servers and the way they are reassigned.We propose a protocol to implement one of the restricted problems in asynchronous systems. As a case study, we construct a dynamic-weighted atomic storage based on such a protocol.We also discuss the relationship between weight reassignment and asset transfer problems and compare our dynamic-weighted atomic storage with reconfigurable atomic storage
Comparison of Effective Permittivity Retrieval Methods of 3D-Printed Unit Cells for Dielectric Resonator Antenna Applications
No full textInternational audienceIn this paper, three methods to retrieve the effective permittivity of 3D-printed unit cells for dielectric resonator antenna (DRA) applications are compared: Maxwell Garnett approximation (MGA), S-parameters method, and plane wave expansion method (PWEM). More specifically, three common topologies are studied: simple cubic (SC), body-centered cubic (BCC) and face-centered cubic (FCC). From numerical analyses, we explain which method is the most appropriate for designing a DRA using 3D-printed periodic unit cells
E-commerce and parcel delivery: environmental policy with green consumers
No full textInternational audienceWe study how consumers’ environmental awareness (CEA) affects the design of environmental policy in the e-commerce sector. We also examine if there is a need for regulation requiring delivery operators to reveal their emissions. We consider a model with two retailers who sell a differentiated product and two parcel delivery operators. Delivery generates CO2 emissions and their total level creates a global (atmosphere) externality. We assume that it is more expensive for the delivery operator to use less polluting technologies. We consider different scenarios reflecting the type of competition and the vertical structure of the industry. We shown that CEA mitigates the inefficiency of the equilibrium by bringing the level of emissions closer to its optimal level. This is true under perfect and imperfect competition. This efficiency enhancing effect of CEA also affects the design of emissions taxes, which leads to an amended Pigouvian rule. Under perfect competition the tax is reduced by exactly the level of CEA expressed in monetary terms. Under imperfect competition the adjustment exceeds this level
Derivative-free mixed binary necklace optimization for cyclic-symmetry optimal design problems
No full textInternational audienceThis paper presents an adapted trust-region method for computationally expensive black-box optimization problems with mixed binary variables that involve a cyclic symmetry property. Mixed binary problems occur in several practical optimal design problems, e.g., aircraft engine turbines, mooring lines of offshore wind turbines, electric engine stators and rotors. The motivating application for this study is the optimal design of helicopter bladed disk turbo-machines. The necklace concept is introduced to deal with the cyclic symmetry property, and to avoid costly black-box objective functionevaluations at equivalent solutions. An adapted distance is proposed for the discrete-space exploration step of the optimization method. A convergence analysis is presented for the trust-region derivative-free algorithm, DFOb-dH, extended to the mixed-binary case and based on the Hamming distance. The convergence proof is extended to the new algorithm, DFOb-dneck, which is based on the necklace distance. Computational comparison with state-of-the-art black-box optimization methods is performed on a set of analytical problems and on a simplified industrial application
A dynamic control method for extended arrival management using enroute speed adjustment and route change strategy
No full textInternational audienceThe continuous growth of air traffic leads to congestion in the surrounding area of airport. The optimization of the air traffic in this area requires the improvement of management strategies, especially for the arrival air traffic. SESAR has proposed the concept of Extended-Arrival MANagement (E-AMAN), which aims to plan the arrival streams from an earlier stage in order to achieve delay absorption and earlier planning in the en-route phases of flights. Based on this concept, we address a dynamic/on-line air traffic control problem to provide control decisions for flights in order to achieve safety and efficiency during arrival. The dynamic feature is realized by periodically updating the flight information for aircraft trajectory predictions. Sub-problems corresponding to each information update are established. The objective of this problem is to minimize the weighted sum of route congestion and the conflict resolution workload in the enroute segment, and the number of conflicts in the TMA (Terminal Maneuvering Area). A dynamic weight assignment approach is applied for ensuring that as an aircraft get closer to the TMA, its weight for TMA metrics increases accordingly. A case study based on the arrival traffic of the Paris Charles de Gaulle (CDG) airport is investigated by using a meta-heuristic simulated annealing algorithm combined with the rolling horizon approach. Final results are analyzed in terms of the reduction of concerned safety issues, final control decision distribution, and the time transferred through enroute decision change
Social cost of airline delays: Assessment by the use of revenue management data
No full textInternational audienceWe develop a schedule delay model using advanced econometrics techniques, while computing the social cost of passenger delays, in order to propose an alternative to the method of defining such cost that is actually found in the literature. This study has been made possible by obtaining private revenue management and operational data directly from a main European legacy airline. Thanks to MNL models, we compute the arrival time preferences, for all groups of passengers, namely arriving or departing, and short or long stay passengers, and for every day of departure that we have collected in our dataset. Then, we compute the effect of the ex-post modification of the arrival time, created by a delay, on the passenger’s utility. We finally compute two effects on the social welfare cost of delays regarding ex-post schedule displacement: the price effect, which is the sensitivity of passengers regarding schedule displacement, and the volume effect measured by the level of airline delays in terms of time. Then, we compare those two effects across the day, in order to consider the social cost of airline delays as a two-effect phenomenon, instead of being only defined by the aggregated airline delay, in terms of time. Our results show that delays are costlier for passengers making the departing portion of their journey, with a short stay upon arrival, and during certain periods of the day. The originality of our paper principally lies in two aspects: first, studies about the precise computation of the social cost of airline delays regarding ex-post schedule displacement do not exist in the literature. Our paper fills this gap by providing an original method aiming at defining this cost. Second, our study is, to the best of our knowledge, the first to consider the effect of airline delays on the passenger’s utility, at the time of day level, by jointly analyzing revenue management and operational data