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  1. Article: A general optimal operating strategy for commercial membrane distillation facilities

    Gil, Juan D / Mendes, Paulo R.C / Camponogara, E / Roca, Lidia / Álvarez, J.D / Normey-Rico, Julio E

    Renewable energy. 2020 Aug., v. 156

    2020  

    Abstract: The high thermal energy consumption is one of the main drawbacks hampering the commercial implementation of Membrane Distillation (MD) technology. The development of adequate operating strategies can help to reduce these energy requirements. Accordingly, ...

    Abstract The high thermal energy consumption is one of the main drawbacks hampering the commercial implementation of Membrane Distillation (MD) technology. The development of adequate operating strategies can help to reduce these energy requirements. Accordingly, this paper focuses on the optimal management of the array of MD modules composing a commercial-scale MD plant, trying to reduce their thermal energy consumption while ensuring a given water need. For this aim, the array of MD modules is modelled as a Mixed Integer Programming (MIP) system to consider that some modules can be turned on/off depending on the operation specifications. An algorithm based on the Generalized Bender Decomposition (GBD) is then developed for the efficient solution of the problem. This algorithm is incorporated in a Model Predictive Control (MPC) strategy allowing to manage the plant in real time. The effectiveness of the proposed strategy is verified using a practical example. The obtained results are compared with a manual and a previous strategy presented in literature, showing that for a sunny day, around the 65 and 55% of the thermal energy consumed by these methodologies can be saved, which means important thermal energy savings that can be relevant for the industrial implementation of MD technology.
    Keywords algorithms ; distillation ; energy conservation ; energy requirements ; models ; renewable energy sources ; thermal energy
    Language English
    Dates of publication 2020-08
    Size p. 220-234.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2001449-1
    ISSN 0960-1481
    ISSN 0960-1481
    DOI 10.1016/j.renene.2020.04.074
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  2. Article: Optimal thermal energy management of a distributed energy system comprising a solar membrane distillation plant and a greenhouse

    Gil, Juan D / Álvarez, J.D / Roca, Lidia / Sánchez-Molina, J.A / Berenguel, Manuel / Rodríguez, F

    Energy conversion and management. 2019 Oct. 15, v. 198

    2019  

    Abstract: The scarcity of water experienced in Almería (south-eastern Spain), and in Mediterranean countries generally, has the potential to compromise one of its main economic drivers – agriculture. A possible solution is to combine thermal desalination ... ...

    Abstract The scarcity of water experienced in Almería (south-eastern Spain), and in Mediterranean countries generally, has the potential to compromise one of its main economic drivers – agriculture. A possible solution is to combine thermal desalination technologies with crop cultivation. Accordingly, this paper proposes a distributed model predictive controller for the efficient operation of a distributed energy system comprising a solar-powered membrane distillation facility and a greenhouse, which is the most widespread type of crop cultivation in this region. The controller is in charge of calculating the optimal feed flow rates for each of the membrane distillation modules included in the desalination facility, according to the water requirements of the greenhouse and the thermal energy consumption of the membrane distillation plant (one of the main weak points of the technology). Simulation results using models for two real facilities located in Almería are presented; they show how the proposed distributed approach is able to manage industrial-scale plants in an optimal way. In addition, automatic operation is compared with manual operation (a non-optimal one), showing that the operation’s thermal efficiency can be improved by 5 % when applying the proposed technique, while satisfying the water demand. This means important thermal energy savings of around 50 MWh/season less thermal energy consumption for an 8 ha cultivation area.
    Keywords cultivation area ; desalination ; distillation ; energy conservation ; greenhouses ; models ; thermal energy ; water requirement ; Mediterranean region ; Spain
    Language English
    Dates of publication 2019-1015
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000891-0
    ISSN 0196-8904
    ISSN 0196-8904
    DOI 10.1016/j.enconman.2019.111791
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  3. Article: Hector, a new methodology for continuous and pattern-free heliostat field optimization

    Cruz, N.C / Salhi, S / Redondo, J.L / Álvarez, J.D / Berenguel, M / Ortigosa, P.M

    Applied energy. 2018 Sept. 01, v. 225

    2018  

    Abstract: In the framework of central receiver solar plants, the heliostat field can take up to 50% of the initial investment and cause up to 40% of energy loss. The most popular design strategies are based on: (i) forcing heliostats to follow known distribution ... ...

    Abstract In the framework of central receiver solar plants, the heliostat field can take up to 50% of the initial investment and cause up to 40% of energy loss. The most popular design strategies are based on: (i) forcing heliostats to follow known distribution patterns and (ii) iterative selection of positions. However, these methods might produce suboptimal solutions. The evolution of computational platforms allows the development of more flexible approaches. In this work, Hector, a new meta-heuristic aimed at facilitating coordinate-based optimization, is presented. First, since East-West symmetry is imposed, one of those regions is ignored and the number of heliostats to be placed is halved. Second, the selected region is split into separate circular sectors around the receiver. Next, at every iteration, a new heliostat is added to the most promising sector. Then, it is optimized by a user-selected algorithm, as an independent problem, in a continuous search-space. This procedure is repeated until all the required heliostats have been deployed. The computed half is finally cloned into the other one. Two versions of this strategy are proposed. Our empirical results show that, for a given optimizer, better fields are obtained with Hector. The second version yields the best fields but requires more runtime.
    Keywords algorithms ; energy ; solar collectors ; solar energy
    Language English
    Dates of publication 2018-0901
    Size p. 1123-1131.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000772-3
    ISSN 0306-2619
    ISSN 0306-2619
    DOI 10.1016/j.apenergy.2018.05.072
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  4. Article: The thymus is similar to the testis in its pattern of circadian clock gene expression.

    Alvarez, J D / Sehgal, Amita

    Journal of biological rhythms

    2005  Volume 20, Issue 2, Page(s) 111–121

    Abstract: The molecular basis for the circadian clock in mammals consists of a number of genes and proteins that form transcription-translation feedback loops. These loops result in a 24-h rhythm in the expression of mRNA and protein levels. Although the ... ...

    Abstract The molecular basis for the circadian clock in mammals consists of a number of genes and proteins that form transcription-translation feedback loops. These loops result in a 24-h rhythm in the expression of mRNA and protein levels. Although the anatomical site of the central circadian clock is the SCN of the hypothalamus, all of the circadian clock genes are expressed in tissues other than the brain. Moreover, cyclic gene and protein expression occurs in most of these tissues. The best known exception to this rule is the testis, which shows constant rather than cyclic expression of circadian clock genes. Indeed, the testis of multiple animal species displays constant circadian clock gene expression. In recent work, the authors showed that the thymus is similar to the testis in that expression of circadian clock genes is either constant over a 24-h period or cycles with a dampened amplitude, depending on which gene is examined. In the current study, they extend and confirm their findings regarding noncyclic circadian clock gene and protein expression in the testis and the thymus. More important, they also show that expression of these genes in both testis and thymus does not depend on the transcriptional activator, CLOCK, which is necessary for cyclic gene expression in the SCN and in other tissues. These results extend the molecular similarities between the thymus and the testis and suggest that similar mechanisms are at work for regulating expression of circadian clock genes in both tissues. One commonality between these 2 organs is that they are composed primarily of differentiating cells. The authors hypothesize that the circadian clock is not operational in immature, differentiating cells. Possibly, the clock starts in mature cells upon receipt of an initiating signal.
    MeSH term(s) Animals ; CLOCK Proteins ; Gene Expression ; Immunohistochemistry ; Kidney/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mutation ; Polymerase Chain Reaction ; RNA, Messenger/genetics ; RNA, Messenger/metabolism ; Testis/metabolism ; Thymus Gland/metabolism ; Trans-Activators/genetics
    Chemical Substances RNA, Messenger ; Trans-Activators ; CLOCK Proteins (EC 2.3.1.48) ; Clock protein, mouse (EC 2.3.1.48)
    Language English
    Publishing date 2005-04
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S.
    ZDB-ID 896387-3
    ISSN 1552-4531 ; 0748-7304
    ISSN (online) 1552-4531
    ISSN 0748-7304
    DOI 10.1177/0748730404274078
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  5. Article: The Thymus Is Similar to the Testis in Its Pattern of Circadian Clock Gene Expression

    Alvarez, J. D / Sehgal, Amita

    Journal of biological rhythms. 2005 Apr., v. 20, no. 2

    2005  

    Abstract: The molecular basis for the circadian clock in mammals consists of a number of genes and proteins that form transcription-translation feedback loops. These loops result in a 24-h rhythm in the expression of mRNA and protein levels. Although the ... ...

    Abstract The molecular basis for the circadian clock in mammals consists of a number of genes and proteins that form transcription-translation feedback loops. These loops result in a 24-h rhythm in the expression of mRNA and protein levels. Although the anatomical site of the central circadian clock is the SCN of the hypothalamus, all of the circadian clock genes are expressed in tissues other than the brain. Moreover, cyclic gene and protein expression occurs in mostof these tissues. The best known exception to this rule is the testis, which shows constant rather than cyclic expression of circadian clock genes. Indeed, the testis of multiple animal species displays constant circadian clock gene expression. In recent work, the authors showed that the thymus is similar to the testis in that expression of circadian clock genes is either constant over a 24-h period or cycles with a dampened amplitude, depending on which gene is examined. In the current study, they extend and confirm their findings regarding noncyclic circadian clock gene and protein expression in the testis and the thymus. More important, they also show that expression of these genes in both testis and thymus does not depend on the transcriptional activator, CLOCK, which is necessary for cyclic gene expression in the SCN and in other tissues. These results extend the molecular similarities between the thymus and the testis and suggest that similar mechanisms are at work for regulating expression of circadian clock genes in both tissues. One commonality between these 2 organs is that they are composed primarily of differentiating cells. The authors hypothesize that the circadian clock is not operational in immature, differentiating cells. Possibly, the clock starts in mature cells upon receipt of an initiating signal.
    Language English
    Dates of publication 2005-04
    Size p. 111-121.
    Document type Article
    ZDB-ID 896387-3
    ISSN 1552-4531 ; 0748-7304
    ISSN (online) 1552-4531
    ISSN 0748-7304
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  6. Article: Neural network and polynomial approximated thermal comfort models for HVAC systems

    Castilla, M / Álvarez, J.D / Ortega, M.G / Arahal, M.R

    Building and environment. 2013 Jan., v. 59

    2013  

    Abstract: Nowadays, the majority of people carry on their daily activities inside a building. This has motivated research directed to assure several comfort conditions. Thermal comfort is usually maintained by means of HVAC (Heating, Ventilation and Air ... ...

    Abstract Nowadays, the majority of people carry on their daily activities inside a building. This has motivated research directed to assure several comfort conditions. Thermal comfort is usually maintained by means of HVAC (Heating, Ventilation and Air Conditioning) systems. The most widely used thermal comfort index is the PMV (Predictive Mean Vote), which is computed considering measurements of several physical variables. The classical calculation of this index is expensive in computational terms, and the involved measurement requires a relatively extensive sensor network. This work proposes the use of two approximated models for the PMV index, one is based on an artificial neural network and the other makes use of polynomial expansions, aimed at using these approximated indices within model predictive control frameworks. In this context, the advantages of using approximated models are two-fold: the computational cost of the calculation of the index is reduced, allowing its use in real-time control of HVAC systems; and the network sensor size is decreased. These advantages entail economic benefits and promote the deployment of comfort controllers in larger structures. This paper illustrates the development of the above cited approximated models and includes experimental tests that rate the accuracy and benefits of the proposed models.
    Keywords air conditioning ; heat ; neural networks ; people
    Language English
    Dates of publication 2013-01
    Size p. 107-115.
    Publishing place Elsevier Ltd
    Document type Article
    ISSN 0360-1323
    DOI 10.1016/j.buildenv.2012.08.012
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  7. Article ; Online: International liquid biopsy standardization alliance white paper.

    Connors, Dana / Allen, Jeff / Alvarez, J D / Boyle, Jennifer / Cristofanilli, Massimo / Hiller, Carolyn / Keating, Susan / Kelloff, Gary / Leiman, Lauren / McCormack, Robert / Merino, Diana / Morgan, Emily / Pantel, Klaus / Rolfo, Christian / Serrano, Maria Jose / Pia Sanzone, A / Schlange, Thomas / Sigman, Caroline / Stewart, Mark

    Critical reviews in oncology/hematology

    2020  Volume 156, Page(s) 103112

    Abstract: The promise of precision medicine as a model to customize health care to the individual patient is heavily dependent upon new genetic tools to classify and characterize diseases and their hosts. Liquid biopsies serve as a safe alternative to solid ... ...

    Abstract The promise of precision medicine as a model to customize health care to the individual patient is heavily dependent upon new genetic tools to classify and characterize diseases and their hosts. Liquid biopsies serve as a safe alternative to solid biopsies and are thus a useful and critical component to fully realizing personalized medicine. The International Liquid Biopsy Standardization Alliance (ILSA) comprises organizations and foundations that recognize the importance of working towards the global use of liquid biopsy in oncology practice to support clinical decision making and regulatory considerations and seek to promote it in their communities. This manuscript provides an overview of the independent liquid biopsy- and standardization-based programs engaged with ILSA, their objectives and progress to date, and the tools and resources each is developing to contribute to the field. It also describes the unique areas of effort as well as synergy found within the group.
    MeSH term(s) Biomarkers, Tumor ; Biopsy ; Humans ; Liquid Biopsy ; Neoplastic Cells, Circulating ; Precision Medicine
    Chemical Substances Biomarkers, Tumor
    Language English
    Publishing date 2020-09-30
    Publishing country Netherlands
    Document type Journal Article ; Review
    ZDB-ID 605680-5
    ISSN 1879-0461 ; 0737-9587 ; 1040-8428
    ISSN (online) 1879-0461
    ISSN 0737-9587 ; 1040-8428
    DOI 10.1016/j.critrevonc.2020.103112
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  8. Article: Circadian rhythms: finer clock control.

    Alvarez, J D / Sehgal, Amita

    Nature

    2002  Volume 419, Issue 6909, Page(s) 798–799

    MeSH term(s) ARNTL Transcription Factors ; Animals ; Basic Helix-Loop-Helix Transcription Factors ; Biological Clocks/genetics ; CLOCK Proteins ; Cell Cycle Proteins ; Circadian Rhythm/genetics ; Cryptochromes ; Drosophila Proteins ; Eye Proteins ; Feedback, Physiological ; Flavoproteins/genetics ; Gene Expression Regulation ; Homeodomain Proteins/chemistry ; Homeodomain Proteins/metabolism ; Humans ; Nuclear Proteins/genetics ; Period Circadian Proteins ; Photoreceptor Cells, Invertebrate ; Receptors, G-Protein-Coupled ; Trans-Activators/metabolism ; Transcription Factors/chemistry ; Transcription Factors/metabolism
    Chemical Substances ARNTL Transcription Factors ; BMAL1 protein, human ; BHLHE40 protein, human ; BHLHE41 protein, human ; Basic Helix-Loop-Helix Transcription Factors ; Cell Cycle Proteins ; Cryptochromes ; Drosophila Proteins ; Eye Proteins ; Flavoproteins ; Homeodomain Proteins ; Nuclear Proteins ; PER1 protein, human ; Period Circadian Proteins ; Receptors, G-Protein-Coupled ; Trans-Activators ; Transcription Factors ; cry protein, Drosophila ; CLOCK Proteins (EC 2.3.1.48) ; CLOCK protein, human (EC 2.3.1.48)
    Language English
    Publishing date 2002-10-22
    Publishing country England
    Document type News ; Comment
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/419798a
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  9. Article: REV-ving up the clock.

    Alvarez, J D / Sehgal, Amita

    Developmental cell

    2002  Volume 3, Issue 2, Page(s) 150–152

    Abstract: Circadian rhythms are generated by a transcription/translation feedback loop consisting of two limbs, one positive and one negative. The nuclear orphan receptor, REV-ERBalpha, is identified as a molecular link coupling these two limbs. ...

    Abstract Circadian rhythms are generated by a transcription/translation feedback loop consisting of two limbs, one positive and one negative. The nuclear orphan receptor, REV-ERBalpha, is identified as a molecular link coupling these two limbs.
    MeSH term(s) Animals ; Biological Clocks/genetics ; Circadian Rhythm/genetics ; DNA-Binding Proteins ; Feedback/physiology ; Humans ; Mice ; Mice, Knockout/genetics ; Mice, Knockout/metabolism ; Nuclear Receptor Subfamily 1, Group D, Member 1 ; Protein Biosynthesis/genetics ; Proteins/genetics ; Proteins/metabolism ; Receptors, Cytoplasmic and Nuclear ; Transcription Factors/genetics ; Transcription, Genetic/genetics
    Chemical Substances DNA-Binding Proteins ; NR1D1 protein, human ; Nr1d1 protein, mouse ; Nuclear Receptor Subfamily 1, Group D, Member 1 ; Proteins ; Receptors, Cytoplasmic and Nuclear ; Transcription Factors
    Language English
    Publishing date 2002-08-23
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 2054967-2
    ISSN 1878-1551 ; 1534-5807
    ISSN (online) 1878-1551
    ISSN 1534-5807
    DOI 10.1016/s1534-5807(02)00225-3
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  10. Article: Repair of a spigelian hernia.

    Broughton, G / Alvarez, J D

    Journal of the American College of Surgeons

    1997  Volume 185, Issue 5, Page(s) 490–491

    MeSH term(s) Dissection ; Hernia, Ventral/diagnosis ; Hernia, Ventral/surgery ; Humans
    Language English
    Publishing date 1997-11
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1181115-8
    ISSN 1879-1190 ; 1072-7515
    ISSN (online) 1879-1190
    ISSN 1072-7515
    DOI 10.1016/s1072-7515(97)00071-9
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