LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 7 of total 7

Search options

  1. Article ; Online: Early detection of new pandemic waves. Control chart and a new surveillance index.

    Cildoz, Marta / Gaston, Martin / Frias, Laura / Garcia-Vicuña, Daniel / Azcarate, Cristina / Mallor, Fermin

    PloS one

    2024  Volume 19, Issue 2, Page(s) e0295242

    Abstract: The COVID-19 pandemic highlights the pressing need for constant surveillance, updating of the response plan in post-peak periods and readiness for the possibility of new waves of the pandemic. A short initial period of steady rise in the number of new ... ...

    Abstract The COVID-19 pandemic highlights the pressing need for constant surveillance, updating of the response plan in post-peak periods and readiness for the possibility of new waves of the pandemic. A short initial period of steady rise in the number of new cases is sometimes followed by one of exponential growth. Systematic public health surveillance of the pandemic should signal an alert in the event of change in epidemic activity within the community to inform public health policy makers of the need to control a potential outbreak. The goal of this study is to improve infectious disease surveillance by complementing standardized metrics with a new surveillance metric to overcome some of their difficulties in capturing the changing dynamics of the pandemic. At statistically-founded threshold values, the new measure will trigger alert signals giving early warning of the onset of a new pandemic wave. We define a new index, the weighted cumulative incidence index, based on the daily new-case count. We model the infection spread rate at two levels, inside and outside homes, which explains the overdispersion observed in the data. The seasonal component of real data, due to the public surveillance system, is incorporated into the statistical analysis. Probabilistic analysis enables the construction of a Control Chart for monitoring index variability and setting automatic alert thresholds for new pandemic waves. Both the new index and the control chart have been implemented with the aid of a computational tool developed in R, and used daily by the Navarre Government (Spain) for virus propagation surveillance during post-peak periods. Automated monitoring generates daily reports showing the areas whose control charts issue an alert. The new index reacts sooner to data trend changes preluding new pandemic waves, than the standard surveillance index based on the 14-day notification rate of reported COVID-19 cases per 100,000 population.
    MeSH term(s) Humans ; Pandemics/prevention & control ; COVID-19/epidemiology ; Public Health Surveillance ; Disease Outbreaks/prevention & control ; Records
    Language English
    Publishing date 2024-02-12
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2267670-3
    ISSN 1932-6203 ; 1932-6203
    ISSN (online) 1932-6203
    ISSN 1932-6203
    DOI 10.1371/journal.pone.0295242
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  2. Article: Tactical and operational management of wind energy systems with storage using a probabilistic forecast of the energy resource

    Azcárate, Cristina / Fermín Mallor / Pedro Mateo

    Renewable energy. 2017 Mar., v. 102

    2017  

    Abstract: The storage of energy facilitates the management of renewable energy systems by reducing the mismatch between the supplied energy and the forecasted production due to forecasting errors. The storage increases the reliability of the renewable energy ... ...

    Abstract The storage of energy facilitates the management of renewable energy systems by reducing the mismatch between the supplied energy and the forecasted production due to forecasting errors. The storage increases the reliability of the renewable energy system and enables participation in the electricity market by committing to the sale of electricity for the following day. Nevertheless, the inclusion of the energy storage capacity requires the development of new management policies. In this paper, we propose a management strategy for a renewable energy system with storage capacity that integrates tactical and operational decisions in a single mathematical model that makes use of an updated probabilistic wind speed forecast. Management policies are obtained by solving a sequence of rolling-horizon stochastic optimization problems whose formulation is inspired by the Stochastic Approximation Average technique. The management policies are illustrated by their application to wind-farms using hydrogen as the energy storage medium.
    Keywords electricity ; energy ; hydrogen ; issues and policy ; markets ; mathematical models ; wind farms ; wind power ; wind speed
    Language English
    Dates of publication 2017-03
    Size p. 445-456.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2001449-1
    ISSN 0960-1481
    ISSN 0960-1481
    DOI 10.1016/j.renene.2016.10.064
    Database NAL-Catalogue (AGRICOLA)

    More links

    Kategorien

  3. Article: Combining optimization with simulation to obtain credible models for intensive care units

    Mallor, Fermín / Azcárate, Cristina

    Operations research in the public sector and nonprofit organizations , p. 255-271

    2014  , Page(s) 255–271

    Author's details Fermín Mallor, Cristina Azcárate
    Language English
    Size graph. Darst.
    Publisher Springer
    Publishing place New York, NY
    Document type Article
    Database ECONomics Information System

    More links

    Kategorien

  4. Article: Optimal control of ICU patient discharge

    Mallor, Fermín / Azcárate, Cristina / Barado, Julio

    Health care management science Vol. 18, No. 3 , p. 234-250

    from theory to implementation

    2015  Volume 18, Issue 3, Page(s) 234–250

    Author's details Fermín Mallor; Cristina Azcárate; Julio Barado
    Keywords Queuing theory ; Healthcare ; Optimization ; Control problem ; Simulation ; Intensive care unit ; Length of stay
    Language English
    Size graph. Darst.
    Publisher Springer Science + Business Media
    Publishing place Norwell, Mass. [u.a.]
    Document type Article
    ZDB-ID 1469148-6
    ISSN 1572-9389 ; 1386-9620
    ISSN (online) 1572-9389
    ISSN 1386-9620
    Database ECONomics Information System

    More links

    Kategorien

  5. Article: Optimal control of ICU patient discharge: from theory to implementation.

    Mallor, Fermín / Azcárate, Cristina / Barado, Julio

    Health care management science

    2015  Volume 18, Issue 3, Page(s) 234–250

    Abstract: This paper deals with the management of scarce health care resources. We consider a control problem in which the objective is to minimize the rate of patient rejection due to service saturation. The scope of decisions is limited, in terms both of the ... ...

    Abstract This paper deals with the management of scarce health care resources. We consider a control problem in which the objective is to minimize the rate of patient rejection due to service saturation. The scope of decisions is limited, in terms both of the amount of resources to be used, which are supposed to be fixed, and of the patient arrival pattern, which is assumed to be uncontrollable. This means that the only potential areas of control are speed or completeness of service. By means of queuing theory and optimization techniques, we provide a theoretical solution expressed in terms of service rates. In order to make this theoretical analysis useful for the effective control of the healthcare system, however, further steps in the analysis of the solution are required: physicians need flexible and medically-meaningful operative rules for shortening patient length of service to the degree needed to give the service rates dictated by the theoretical analysis. The main contribution of this paper is to discuss how the theoretical solutions can be transformed into effective management rules to guide doctors' decisions. The study examines three types of rules based on intuitive interpretations of the theoretical solution. Rules are evaluated through implementation in a simulation model. We compare the service rates provided by the different policies with those dictated by the theoretical solution. Probabilistic analysis is also included to support rule validity. An Intensive Care Unit is used to illustrate this control problem. The study focuses on the Markovian case before moving on to consider more realistic LoS distributions (Weibull, Lognormal and Phase-type distribution).
    MeSH term(s) Computer Simulation ; Delivery of Health Care ; Health Services Research ; Humans ; Intensive Care Units/organization & administration ; Length of Stay ; Models, Theoretical ; Patient Admission ; Patient Discharge ; Planning Techniques
    Language English
    Publishing date 2015-09
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1469148-6
    ISSN 1572-9389 ; 1386-9620
    ISSN (online) 1572-9389
    ISSN 1386-9620
    DOI 10.1007/s10729-015-9320-8
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  6. Article: Peaking strategies for the management of wind-H₂ energy systems

    Azcárate, Cristina / Blanco, Rosa / Mallor, Fermín / Garde, Raquel / Aguado, Mónica

    Renewable energy. 2012 Nov., v. 47

    2012  

    Abstract: In recent years, growing attention has been paid to the use of renewable resources to produce electricity. One of the main drawbacks of generating electricity through wind power is the randomness of input, which obviously results in a random output of ... ...

    Abstract In recent years, growing attention has been paid to the use of renewable resources to produce electricity. One of the main drawbacks of generating electricity through wind power is the randomness of input, which obviously results in a random output of energy. This means that peak output does not always coincide with peak demand. Nevertheless, demand drives prices, making output regulation essential. Thus, improvements in energy management aimed at satisfying demand and increasing profits need to include output regulation mechanisms. This calls for the introduction of new equipment for energy storage and new management strategies. This paper presents a simulation model, which incorporates the important equipment that compose the wind-H₂ energy system (wind turbines, inverters, electrolysers, H₂-storage tank, fuel cells,…) and the random elements of the stochastic environment in which the energy system evolves (wind speed, wind speed forecast error and electricity prices). The main contribution of the paper is to present and analyze a set of new proposed management policies named “peaking strategies”, which are based on the conversion of electricity into hydrogen during price troughs and the use of the stored hydrogen to produce electricity during the day's demand (thus price) peaks. We present a very flexible set of management policies with different levels of participation of the decision maker: some decisions can be made by the decision maker while leaving others to optimization processes. To achieve such a decision framework we break down the management policy into a set of decisions with different time horizon (strategic, tactical and operational decisions).
    Keywords electricity ; energy ; fuel cells ; hydrogen ; issues and policy ; prices ; profits and margins ; simulation models ; wind power ; wind speed ; wind turbines
    Language English
    Dates of publication 2012-11
    Size p. 103-111.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2001449-1
    ISSN 0960-1481
    ISSN 0960-1481
    DOI 10.1016/j.renene.2012.04.016
    Database NAL-Catalogue (AGRICOLA)

    More links

    Kategorien

  7. Article: Peaking strategies for the management of wind-H₂ energy systems

    Azcárate, Cristina / Blanco, Rosa / Mallor, Fermín / Garde, Raquel / Aguado, Mónica

    Renewable energy

    Volume v. 47

    Abstract: In recent years, growing attention has been paid to the use of renewable resources to produce electricity. One of the main drawbacks of generating electricity through wind power is the randomness of input, which obviously results in a random output of ... ...

    Abstract In recent years, growing attention has been paid to the use of renewable resources to produce electricity. One of the main drawbacks of generating electricity through wind power is the randomness of input, which obviously results in a random output of energy. This means that peak output does not always coincide with peak demand. Nevertheless, demand drives prices, making output regulation essential. Thus, improvements in energy management aimed at satisfying demand and increasing profits need to include output regulation mechanisms. This calls for the introduction of new equipment for energy storage and new management strategies. This paper presents a simulation model, which incorporates the important equipment that compose the wind-H₂ energy system (wind turbines, inverters, electrolysers, H₂-storage tank, fuel cells,…) and the random elements of the stochastic environment in which the energy system evolves (wind speed, wind speed forecast error and electricity prices). The main contribution of the paper is to present and analyze a set of new proposed management policies named “peaking strategies”, which are based on the conversion of electricity into hydrogen during price troughs and the use of the stored hydrogen to produce electricity during the day's demand (thus price) peaks. We present a very flexible set of management policies with different levels of participation of the decision maker: some decisions can be made by the decision maker while leaving others to optimization processes. To achieve such a decision framework we break down the management policy into a set of decisions with different time horizon (strategic, tactical and operational decisions).
    Keywords profits and margins ; fuel cells ; wind speed ; hydrogen ; issues and policy ; prices ; wind turbines ; electricity ; simulation models ; wind power ; energy
    Language English
    Document type Article
    ISSN 0960-1481
    Database AGRIS - International Information System for the Agricultural Sciences and Technology

    More links

    Kategorien

To top