Event-based control of basic wastewater treatment plant control loops

[Abstract] This paper addresses the problem of basic control loops in wastewater treatment plants. By basic control loops we are referring to the traditional dissolved oxygen and nitrates. They are the basic controls more sophisticated control solutions can be based upon. Therefore it is important that these loops perform in an efficient way. The problem is addressed here within the framework provided by the Benchmark Simulation Model Number 1 (BSM1) and by the use of an event-based solution. It will be verified that the solution can slightly improve the performance of the already exiting controllers both at loop level as well as at plant operation level.[Resumen] Este documento aborda el problema de los bucles de control básicos en las plantas de tratamiento de aguas residuales. Por bucles de control básicos nos referimos a los tradicionales disueltos de oxígeno y nitratos. Son los controles básicos en los que se pueden basar las soluciones de control más sofisticadas. Por lo tanto, es importante que estos bucles funcionen de manera eficiente. El problema se aborda aquí dentro del marco provisto por el Número de modelo de simulación de referencia (BSM1) y por el uso de una solución basada en eventos. Se verificará que la solución puede mejorar ligeramente el rendimiento de los controladores que ya existen, tanto a nivel de bucle como a nivel de operación de la planta

PID Tuning: Analytical approach based on the weighted Sensitivity problem

[EN] The PID controller is the most common option in the realm of control applications and is dominant in the process control industry. Among the related analytical methods, Internal Model Control (IMC) has gained remarkable industrial acceptance due to its robust nature and good set-point responses. However, the traditional application of IMC results in poor load disturbance rejection for lag-dominant and integrating plants. This work presents an IMC-like design method which avoids this common pitfall and is devised to work well for plants of modest complexity, for which analytical PID tuning is plausible. For simplicity, the design only focuses on the closed-loop sensitivity function. The approach provides model-based tuning of single-loop PID controllers in terms of the robustness/performance and servo/regulator trade-offs. Although the robustness/performance compromise is commonly considered, it is not so common to also take into account, for example, the conflict between input and output disturbances, referred also as the servo/regulator trade-off. As interested in providing a unified tuning approach, it is shown how the proposed methodology allows to deal with different process dynamics in a unified way.[ES] El controlador PID es la opción más común en el ámbito de las aplicaciones de control, siendo la opción predominante en el control de procesos industriales. Entre los métodos analíticos más usuales utilizados para su diseño, el Control por Modelo Interno (IMC) ha ganado una notable aceptación industrial debido a su naturaleza robusta y buenas respuestas ante cambios de consigna. Sin embargo, la aplicación tradicional del IMC da como resultado un bajo rendimiento para el rechazo de perturbaciones en carga para plantas integradoras y/o con largas constantes de tiempo. Este trabajo presenta un método de diseño, basado en IMC, que evita esta deficiencia y está diseñado para funcionar bien en plantas de complejidad moderada para las cuales, por otro lado, el ajuste analítico de un controlador PID es plausible. Por simplicidad, el diseño solo se centra en la función de sensibilidad en lazo cerrado. El enfoque proporciona un ajuste basado en modelo en términos de los compromisos robustez/rendimiento y de servo/regulación. Aunque comúnmente se considera el compromiso robustez/rendimiento, no es tan común tener en cuenta también, por ejemplo, el conflicto entre las perturbaciones de entrada y salida, también conocido como el compromiso servo/regulación. Con el objetivo de proporcionar un enfoque de ajuste unificado, se muestra como la metodología propuesta permite tratar diferentes dinámicas de proceso de manera unificada.Los autores desean agradecer al Ministerio de Economía y Competitividad bajo las subvenciones DPI-2016-77271-R y PID2019-105434RB-C33 por la ayuda que han supuesto en la elaboración de los trabajos que han conducido a los desarrollos aquí presentados.Vilanova, R.; Alcántara, S.; Pedret, C. (2021). Sintonía de controladores PID: un enfoque analítico basado en el moldeo de la función de sensibilidad. Revista Iberoamericana de Automática e Informática industrial. 18(4):313-326. https://doi.org/10.4995/riai.2021.15422OJS313326184Alcántara, S., Vilanova, R., Pedret, C., 2013. PID control in terms of robustness/performance and servo/regulator trade-offs: A unifying approach to balanced autotuning. Journal of Process Control 23 (4), 527 - 542. https://doi.org/10.1016/j.jprocont.2013.01.003Alcántara, S., Pedret, C., Vilanova, R., 2010. On the model matching approach to PID design: Analytical perspective for robust Servo/Regulator tradeoff tuning. Journal of Process Control 20 (5), 596 - 608. https://doi.org/10.1016/j.jprocont.2010.02.011Alcántara, S., Pedret, C., Vilanova, R., Skogestad, S., 2011a. Generalized Internal Model Control for balancing input/output disturbance response. Industrial & Engineering Chemistry Research 50 (19), 11170-11180. https://doi.org/10.1021/ie200717zAlcántara, S., Vilanova, R., Pedret, C., 2020. PID Tuning: A Modern Approach via the Weighted Sensitivity Problem (1st ed.). CRC Press. https://doi.org/10.1201/9780429325335-1Alcántara, S., Vilanova, R., Pedret, C., Skogestad, S., 2012. A look into robustness/performance and servo/regulation issues in PI tuning. In: Proc. of the IFAC Conf. on Advances in PID Control PID'12. https://doi.org/10.3182/20120328-3-IT-3014.00031Alcántara, S., Zhang, W., Pedret, C., Vilanova, R., Skogestad, S., 2011b. IMC-like analytical H-inf design with S/SP mixed sensitivity consideration: Utility in PID tuning guidance. Journal of Process Control 21 (6), 976 - 985. https://doi.org/10.1016/j.jprocont.2011.04.007Alfaro, V. M., Vilanova, R., 2013a. Performance and Robustness Considerations for Tuning of Proportional Integral/Proportional Integral Derivative Controllers with Two Input Filters. Industrial & Engineering Chemistry Research 52, 18287-18302. https://doi.org/10.1021/ie4012694Alfaro, V. M., Vilanova, R., 2013b. Robust tuning of 2DoF five-parameters PID controllers for inverse response controlled processes. Journal of Process Control 23, 453-462. https://doi.org/10.1016/j.jprocont.2013.01.005Alfaro, V. M., Vilanova, R., September 2013c. Simple robust tuning of 2DoF PID controllers from a performance/robustness trade-off analysis. Asian Journal of Control 15 (5), 1-14. https://doi.org/10.1002/asjc.653Alfaro, V. M., Vilanova, R., 2016. Model-Reference Robust Tuning of PID Controllers. Springer International Publishing AG, Gewerbestrasse 11, 6330 Cham, Switzerland, ISBN 978-3-319-28213-8.Alfaro, V. M., Vilanova, R., Méndez, R., Lafuente, J., 2010. Performance/Robustness Tradeoff Analysis of PI/PID Servo and Regulatory Control Systems. In: Proc. of the IEEE International Conference on Industrial Technology. https://doi.org/10.1109/ICIT.2010.5472662Arrieta, O., Vilanova, R., 2012. Simple servo/regulation proportional-integralderivative (pid) tuning rules for arbitrary ms-based robustness achievement. Industrial & Engineering Chemistry Research 51 (6), 2666-2674. https://doi.org/10.1021/ie201655cArrieta, O., Vilanova, R., Rojas, J. D., Meneses, M., 2016. Improved pid controller tuning rules for performance degradation/robustness increase trade-off. Electrical Engineering 98 (3), 233-243. https://doi.org/10.1007/s00202-016-0361-xArrieta, O., Visioli, A., Vilanova, R., 2010. PID autotuning for weighted servo/regulation control operation. Journal of Process Control 20 (4), 472 -480. https://doi.org/10.1016/j.jprocont.2010.01.002Astrom, K., Hagglund, T., 2004. Revisiting the Ziegler-Nichols step response method for PID control. J. Process Control 14, 635-650. https://doi.org/10.1016/j.jprocont.2004.01.002Astrom, K., Hagglund, T., 2005. Advanced PID control. ISA - The Instrumentation, Systems, and Automation Society.Chien, I. L., Fruehauf, P. S., 1990. Consider IMC tuning to improve controller performance. Chemical Engineering Progress 86 (10), 33 - 41.Dehghani, A., Lanzon, A., Anderson, B., 2006. H1 design to generalize internalmodel control. Automatica 42 (11), 1959 - 1968.Grimholt, C., Skogestad, S., 2012. Optimal PI Control and Verifcation of the SIMC Tuning Rule. In: Proc. of the IFAC Conf. on Advances in PID Control PID'12. https://doi.org/10.3182/20120328-3-IT-3014.00003Horn, I. G., Arulandu, J. R., Gombas, C. J., VanAntwerp, J. G., Braatz, R. D., 1996. Improved Filter Design in Internal Model Control. Industrial & Engineering Chemistry Research 35 (10), 3437 - 3441. https://doi.org/10.1021/ie9602872Huba, M., 2012. Setpoint Versus Disturbance Responses of the IPDT Plant. In: Proc. of the IFAC Conf. on Advances in PID Control PID'12. https://doi.org/10.3182/20120328-3-IT-3014.00070J.Shi, W.S.Lee, 2004. Set Point Response and Disturbance Rejection Tradeoff for Second-Order Plus Dead Time Processes. In: Asian Control Conference.Kristiansson, B., Lennartson, B., 1998. Optimal PID controllers for unstable and resonant plants. In: Proc. of the IEEE Conference on Decision and Control. pp. 4380-4381.Kurokawa, R., Sato, T., Vilanova, R., Konishi, Y., 2019. Discrete-time firstorder plus dead-time model-reference trade-off pid control design. Applied Sciences 9 (16). https://doi.org/10.3390/app9163220Kurokawa, R., Sato, T., Vilanova, R., Konishi, Y., 2020. Design of optimal pid control with a sensitivity function for resonance phenomenon-involved second-order plus dead-time system. Journal of the Franklin Institute 357 (7), 4187-4211. https://doi.org/10.1016/j.jfranklin.2020.03.015Leva, A., Maggio, M., 2012. Model-Based PI(D) Autotuning. In: PID Control in the Third Millennium. Lessons Learned and New Approaches. Springer. https://doi.org/10.1007/978-1-4471-2425-2_2Mercader, P., Astrom, K. J., Baños, A., Hagglund, T., 2017a. Robust pid design based on qft and convex?concave optimization. IEEE Transactions on Control Systems Technology 25 (2), 441-452. https://doi.org/10.1109/TCST.2016.2562581Mercader, P., Baños, A., 2017. A pi tuning rule for integrating plus dead time processes with parametric uncertainty. ISA Transactions 67, 246-255. https://doi.org/10.1016/j.isatra.2017.01.025Mercader, P., Baños, A., Vilanova, R., 2017b. Robust proportional-integral-derivative design for processes with interval parametric uncertainty. IET Control Theory & Applications 11 (7), 016-1023. https://doi.org/10.1049/iet-cta.2016.1239Mercader, P., Soltesz, K., Baños, A., 2017c. Robust pid design by chance-constrained optimization. Journal of the Franklin Institute 354 (18), 8217-8231. https://doi.org/10.1016/j.jfranklin.2017.10.017Meza, G. R., Ferragud, X. B., Saez, J. S., Dur, J. M. H., 2016. Controller Tuning with Evolutionary Multiobjective Optimization: A Holistic Multiobjective Optimization Design Procedure, 1st Edition. Springer Publishing Company, Incorporated.Middleton, R. H., Graebe, S. F., 1999. Slow stable open-loop poles: to cancel or not to cancel. Automatica 35 (5), 877-886. https://doi.org/10.1016/S0005-1098(98)00220-9Morari, M., Zafiriou, E., 1989. Robust Process Control. Prentice-Hall International.Panagopoulos, H., Astrom, K. J., 2000. PID control design and H1 loop shaping. International Journal of Robust and Nonlinear Control 10 (15), 1249-1261. https://doi.org/10.1002/1099-1239(20001230)10:153.0.CO;2-7Pedret, C., Vilanova, R., Moreno, R., Serra, I., 2002. A refinement procedure for PID controller tuning. Computers & Chemical Engineering 26 (6), 903- 908. https://doi.org/10.1016/S0098-1354(02)00011-XRivera, D. E., Morari, M., Skogestad, S., 1986. Internal model control: PID controller design. Industrial & Engineering Chemistry Process Design and Development 25 (1), 252 - 265. https://doi.org/10.1021/i200032a041Rodriguez, C., September 2020. Revisiting the simplified imc tuning rules for low-order controllers: Novel 2dof feedback controller. IET Control Theory & Applications 14, 1700-1710(10). https://doi.org/10.1049/iet-cta.2019.0821Ruscio, D. D., 2010. On Tuning PI Controllers for Integrating Plus Time Delay Systems. 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One-year dietary supplementation with walnuts modifies exosomal miRNA in elderly subjects

Purpose: Epidemiological studies and clinical trials support the association of nut consumption with a lower risk of prevalent non-communicable diseases, particularly cardiovascular disease. However, the molecular mechanisms underlying nut benefits remain to be fully described. MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression and play a pivotal role in health and disease. Exosomes are extracellular vesicles released from cells and mediate intercellular communication. Whether nut consumption modulates circulating miRNAs (c-miRNAs) transported in exosomes is poorly described. Methods: Cognitively healthy elderly subjects were randomized to either control (n = 110, abstaining from walnuts) or daily supplementation with walnuts (15% of their total energy, ≈30–60 g/day, n = 101) for 1-year. C-miRNAs were screened in exosomes isolated from 10 samples, before and after supplementation, and identified c-miRNA candidates were validated in the whole cohort. In addition, nanoparticle tracking analysis and lipidomics were assessed in pooled exosomes from the whole cohort. Results: Exosomal hsa-miR-32-5p and hsa-miR-29b-3p were consistently induced by walnut consumption. No major changes in exosomal lipids, nanoparticle concentration or size were found. Conclusion: Our results provide novel evidence that certain c-miRNAs transported in exosomes are modulated by walnut consumption. The extent to which this finding contributes to the benefits of walnuts deserves further research.Fundacion Ramon Areces (CIVP18A3888) Madrid, Spain; the Instituto de Salud Carlos III-Fondo de Investigacion Sanitaria–Fondo Europeo de Desarrollo Regional (grant PI15/01014 and PI18/01152), and the Spanish Agencia Estatal de Investigacion and European Feder Funds (AGL2016-78922-R, PID2019-109369RB-I00, RTI2018-093873-A-I00 and BIO2017-86500-R). AS-V is recipient of the Instituto de Salud Carlos III Miguel Servet II fellowship (grant CP II 17/00029

The Use of Multivitamin/Multimineral Supplements:A Modified Delphi Consensus Panel Report

PURPOSE: Evidence supporting the use of dietary supplements, in particular, multivitamin/multimineral supplements (MVMS), has been mixed, complicating the ability of health care professionals to recommend their use. To clarify the role that MVMS can play in supporting human health, a series of consensus statements was developed based on expert opinion. METHODS: A panel of 14 international experts in nutritional science and health care was convened to develop consensus statements related to using MVMS in supporting optimal human health. The modified Delphi process included 2 rounds of remote voting and a final round of voting at a roundtable meeting where evidence summaries were presented and discussed. The level of agreement with each of 9 statements was rated on a 5-point Likert scale: agree strongly; agree with reservation; undecided; disagree; or disagree strongly. Consensus was predefined as ≥80% of the panel agreeing strongly or agreeing with reservation to a given statement. FINDINGS: Consensus was reached for all statements. The panel determined that MVMS can broadly improve micronutrient intakes when they contain at least the micronutrients that are consumed insufficiently or have limited bioavailability within a specified population. MVMS formulations may also be individualized according to age, sex, life cycle, and/or other selected characteristics. There are specific biological processes and health outcomes associated with deficient, inadequate, and adequate micronutrient levels. Adequate intake is necessary for normal biological functioning required for good health; in some instances, higher than recommended micronutrient intakes have the potential to provide additional health benefits. Meeting daily intakes established by dietary reference values should be an explicit public health goal for individuals and populations. Use of MVMS is one approach to ensure that adequate micronutrient needs are met in support of biological functions necessary to maintain health. Long-term use of MVMS not exceeding the upper limit of recommended intakes has been determined to be safe in healthy adults. There is insufficient evidence to indicate that MVMS are effective for the primary prevention of chronic medical conditions, including cardiovascular disease and cancer. However, for certain otherwise healthy subpopulations (eg, pregnant women, older adults) and some individuals with existing medical conditions who experience inadequacies in micronutrient intake, addressing inadequacies by using MVMS can provide health benefits. IMPLICATIONS: This consensus panel has described key issues related to the use of MVMS among individuals at risk of or presenting with inadequacies in micronutrient intake or biomarker status

Nutrition and the ageing brain: moving towards clinical applications

The global increases in life expectancy and population have resulted in a growing ageing population and with it a growing number of people living with age-related neurodegenerative conditions and dementia, shifting focus towards methods of prevention, with lifestyle approaches such as nutrition representing a promising avenue for further development. This overview summarises the main themes discussed during the 3 Symposium on "Nutrition for the Ageing Brain: Moving Towards Clinical Applications" held in Madrid in August 2018, enlarged with the current state of knowledge on how nutrition influences healthy ageing and gives recommendations regarding how the critical field of nutrition and neurodegeneration research should move forward into the future. Specific nutrients are discussed as well as the impact of multi-nutrient and whole diet approaches, showing particular promise to combatting the growing burden of age-related cognitive decline. The emergence of new avenues for exploring the role of diet in healthy ageing, such as the impact of the gut microbiome and development of new techniques (imaging measures of brain metabolism, metabolomics, biomarkers) are enabling researchers to approach finding answers to these questions. But the translation of these findings into clinical and public health contexts remains an obstacle due to significant shortcomings in nutrition research or pressure on the scientific community to communicate recommendations to the general public in a convincing and accessible way. Some promising programs exist but further investigation to improve our understanding of the mechanisms by which nutrition can improve brain health across the human lifespan is still required