Revistas
Revista:
JOURNAL OF MODELLING IN MANAGEMENT
ISSN:
1746-5664
Año:
2021
Vol.:
16
N°:
2
Págs.:
464 - 485
Purpose This study aims to reduce carbon emissions and costs in an automobile production plant by improving the operational management efficiency of a serial assembly line assisted by a feeding electric tow vehicle (ETV). Design/methodology/approach A multi-objective function is formulated to minimize the energy consumption of the ETV from which emissions and costs are measured. First, a mixed-integer linear programming model is used to solve the feeding problem for different sizes of the assembly line. Second, a bi-objective optimization (HBOO) model is used to simultaneously minimize the most eco-efficient objectives: the number of completed runs (tours) by the ETV along the assembly line, and the number of visits (stops) made by the ETV to deliver kits of components to workstations. Findings The most eco-efficient strategy is always the bi-objective optimal solution regardless of the size of the assembly line, whereas, for single objectives, the optimization strategy differs depending on the size of the assembly line. Research limitations/implications Instances of the problem are randomly generated to reproduce real conditions of a particular automotive factory according to a previous case study. The optimization procedure allows managers to assess real scenarios improving the assembly line eco-efficiency. These results promote the implementation of automated control of feeding processes in green manufacturing. Originality/value The HBOO-model assesses the assembly line performance with a view to reducing the environmental impact effectively and contributes to reducing the existent gap in the literature. The optimization results define key strategies for manufacturing industries eager to integrate battery-operated motors or to address inefficient traffic of automated transport to curb the carbon footprint.
Revista:
HEALTH CARE MANAG SC
ISSN:
1386-9620
Año:
2020
Vol.:
23
N°:
1
Págs.:
66 - 79
We study the efficiency of operations management in a hospital from the dynamics of the flow of patients. Our principal aim is to characterize strategic departments and seasonal patterns in a hospital from a complex networks approach. Process mining techniques are developed to track out-patients¿ pathways along different departments for the purpose of building weekly networks. In these networks, departments act as nodes with multiple out/in-going arrows connecting other departments. Strategic departments are classified into target and critical departments. On the one hand, target departments, which in this study belong to the oncology area, correspond to those affected by new management policies whose impact is to be assessed. On the other hand, critical departments correspond to the most active departments, the hubs of the networks. Using suitable networks parameters, strategic departments are shown to be highly efficient regardless of the season, which naturally translates into a high level of service offered to patients. In addition, our results show conformance with the new objectives concerning target departments. The methodology presented is shown to be successful in evaluating the efficiency of hospital services in order to enhance process performances, and moreover, it is suitable to be implemented in healthcare management systems at a greater scale and the service industry whenever the flow of clients or customers are involved.
Revista:
PHYSICAL REVIEW E
ISSN:
1539-3755
Año:
2013
Vol.:
87
N°:
3
Págs.:
032902-1 - 032902-7
We show evidence of the frozen dynamics (Kibble-Zurek mechanism) at the transition one-dimensional (1D) front of an extended 1D array of convective oscillators that undergo a secondary subcritical bifurcation. Results correspond to a global synchronization process from nonlocal coupling between the oscillating units. The quenched dynamics exhibits defect trapping at the synchronization front according to the Kibble-Zurek mechanism, predicted for condensed matter systems. A stronger subcriticality prevents the fronts from freezing defects during the quenched transitions. A synchronization model of supercritical oscillating units is proposed to explain differentiation mechanisms in morphogenesis above a critical crossing rate when the frequency of the individual oscillators becomes coherent. The phases of such oscillators are spatially coupled through a Kuramoto-Battogtokh term that leads to the experimentally observed subcriticality. As a consequence, we show that the Kibble-Zurek mechanism overcomes non-locality of a geometrical network above a critical crossing rate.
Autores:
Gómez-Polo, C. (Autor de correspondencia); Soto-Armañanzas, J.; Olivera, J.; et al.
Revista:
INDUSTRIAL AND ENGINEERING CHEMISTRY RESEARCH
ISSN:
0888-5885
Año:
2013
Vol.:
52
N°:
10
Págs.:
3787-3793
Development of a multifunction sensor for detection of environmental parameters such as temperature and relative humidity is described in this work. The multifunctional sensor is based on the combination in the same sensor unit of a magnetoinductive temperature sensor (soft magnetic FeCrSiBCuNb nanocrystalline wire) and a capacitive ceramic element (TiO2 microscale coating) for humidity detection. The sensing principle is based on the changes of electrical impedance of both the inner ferromagnetic wire (self-inductance, L) and the ceramic TiO2 coating (capacitance, C). In the magnetoinductive temperature element, the sensor span can be suitably selected through control of the Curie temperature of the residual amorphous phase (i.e., Cr content of the residual amorphous phase). With respect to the TiO2 coating, its doping with alkali elements (K) improves the humidity sensor sensibility. The designed cylindrical metal/TiO2/metal capacitive structures display resistive switching phenomena (memresistive behavior) that can be employed in design of simplified signal conditioning switches.
Revista:
JOURNAL OF PHYSICS-CONDENSED MATTER
ISSN:
0953-8984
Año:
2013
Vol.:
25
N°:
40
Págs.:
404208
We present a study of the freezing dynamics of topological defects in a subcritical system by
testing the Kibble¿Zurek (KZ) mechanism while crossing a tri-stable region in a
one-dimensional quintic complex Ginzburg¿Landau equation. The critical exponents of the
KZ mechanism and the horizon (KZ-scaling regime) are predicted from the quasistatic study,
and are in full accordance with the quenched study. The correlation length, in the KZ freezing
regime, is corroborated from the number of topological defects and from the spatial
correlation function of the order parameter. Furthermore, we characterize the dynamics to
differentiate three out-of-equilibrium regimes: the adiabatic, the impulse and the free
relaxation. We show that the impulse regime shares a common temporal domain with a fast
exponential increase of the order parameter.
Revista:
JOURNAL OF APPLIED PHYSICS
ISSN:
0021-8979
Año:
2012
Vol.:
112
Págs.:
034507
Evidence of unipolar resistive switching is observed along the aging process of cylindrical microscale Fe-base alloy/TiO2/Au devices (MIM-cells). In the early stages of aging, under low electric fields, we show evidence of the effect of a blocking barrier (a Schottky-type depletion layer) at the active TiO2/Au interface which is measured in the OFF-state before the set process is triggered. Resistance transients after resets, R-OFF(t), provide a relaxation time that is explained in terms of the drifting processes of oxygen vacancies. In the aged stages under high electric fields, a highly insulating behavior is observed in the OFF-state (before the set is produced) which yields fluctuating values of R-OFF. Under these conditions, we show that a recovery of the blocking barrier is still feasible by inverting the polarity of the applied voltage. Further on, the resistance switching is studied at different voltage sweep rates which provide the maximum rate that is necessary to accomplish with the resistive switching dynamics, in order to allow the diffusion of the mobile species.
Revista:
INTERNATIONAL JOURNAL OF BIFURCATION AND CHAOS
ISSN:
0218-1274
Año:
2012
Vol.:
22
N°:
7
Págs.:
1250165-1 - 1250165-10
We present new experimental results on the quenching dynamics of an extended thermo-convective system (a network array of approximately 100 convective oscillators) going through a secondary subcritical bifurcation. We characterize a dynamical phase transition through the nature of the domain walls (1D-fronts) that connect the basic multicellular pattern with the new oscillating one. Two different mechanisms of the relaxing dynamics at the threshold are characterized depending on the crossing rate mu = d epsilon/dt vertical bar(epsilon=0) of the quenched transition. From the analysis of fronts, we show that these mechanisms follow different correlation length scales xi similar to mu(-sigma). Below a critical value mu(c), a slow response dynamics yields a spatiotemporal coherent front with weak coupling between oscillators. Above mu(c), for rapid quenches, defects are trapped at the front with a strong coupling between oscillators, similarly to the Kibble-Zurek mechanism in quenched phase transitions. These defects, pinned to the fronts, yield a strong decay of the correlation length.
Revista:
Magnetohydrodynamics
ISSN:
0024-998X
Año:
2012
Vol.:
48
N°:
1
Págs.:
69 - 75
In this work, we analyze recent results concerning the instabilities created in a layer of liquid metal by the action of time-dependent magnetic fields. The experimental setup allows the characterization of different patterns very close to the threshold. For very low frequencies of the forcing field, the axisymmetric fluid layer destabilizes with different azimuthal wavenumbers. An improved analysis allows the characterization of different patterns for interaction parameter values as low a
Revista:
INTERNATIONAL JOURNAL OF COMPLEX SYSTEMS IN SCIENCE
ISSN:
2174-6036
Año:
2011
Vol.:
1
Págs.:
60 - 64
Revista:
International Journal of Bifurcation and Chaos
ISSN:
0218-1274
Año:
2010
Vol.:
20
N°:
3
Págs.:
835 - 847
In a quasi-1D thermal convective system consisting of a large array of nonlinearly coupled oscillators, clustering is the way to achieve a regime of mostly antiphase synchronized oscillators. This regime is characterized by a spatiotemporal doubling of traveling modes. As the dynamics is explored beyond a spatiotemporal chaos regime (STC) with weak coupling, new interacting modes emerge through a supercritical bifurcation. In this new regime, the system exhibits coherent subsystems of antiphase synchronized oscillators, which are stationary clusters following a spatiotemporal beating phenomena (ZZ regime). This regime is the result of a stronger coupling. We show from a phase mismatch model applied to each oscillator, that these phase coherent domains undergo a global phase instability, meanwhile the interactions between oscillators become nonlocal. For each value of the control parameter we find out the time-varying topology (link matrix) from the contact interactions between oscillators. The new characteristic spatiotemporal scales are extracted from the antiphase correlations at the time intervals defined by the link matrix. The interpretation of these experimental results contributes to widen the understanding of other complex systems exhibiting similar phase chaotic dynamics in 2D and 3D
Nacionales y Regionales
Título:
Gemelos Digitales para la climatización de edificios (BuildTwin)
Código de expediente:
0011-1383-2022-000015 PC032-033 BuildTwin
Investigador principal:
Jesús Fernando López Fidalgo
Financiador:
GOBIERNO DE NAVARRA
Convocatoria:
2022 GN Proyectos Colaborativos
Fecha de inicio:
01/04/2022
Fecha fin:
30/11/2024
Importe concedido:
370.917,55€
Otros fondos:
-
