Fuzzy adaptive control system of a non-stationary plant with closed-loop passive identifier

Abstract Typically chemical processes have significant nonlinear dynamics, but despite this, industry is conventionally still using PID-based regulatory control systems. Moreover, process units are interconnected, in terms of inlet and outlet material/energy flows, to other neighboring units, thus their dynamic behavior is strongly influenced by these connections and, as a consequence, conventional control systems performance often proves to be poor. This paper proposes a hybrid fuzzy PID control logic, whose tuning parameters are provided in real time. The fuzzy controller tuning is made on the basis of Mamdani controller, also exploiting the results coming from an identification procedure that is carried on when an unmeasured step disturbance of any shape affects the process behavior. In addition, this paper compares a fuzzy logic based PID with PID regulators whose tuning is performed by standard and well-known methods. In some cases the proposed tuning methodology ensures a control performance that is comparable to that guaranteed by simpler and more common tuning methods. However, in case of dynamic changes in the parameters of the controlled system, conventionally tuned PID controllers do not show to be robust enough, thus suggesting that fuzzy logic based PIDs are definitively more reliable and effective

Optimization of uranium crystallization process by using MPC approach

This paper proposes optimization of uranium crystallization process to provide insight into the trade-offs between performance and robustness explicitly. Based on developed mathematical model, which describes the heat and mass transfer processes, behavioral analysis of using PID and MPC controllers was presented. Increasing of crystals outlet and simultaneous decreasing of uranyl nitrate concentration in the liquid outlet showed MPC advantages

Passive Identification is Non Stationary Objects with Closed Loop Control

Typically chemical processes have significant nonlinear dynamics, but despite this, industry is conventionally still using PID-based regulatory control systems. Moreover, process units are interconnected, in terms of inlet and outlet material/energy flows, to other neighbouring units, thus their dynamic behaviour is strongly influenced by these connections and, as a consequence, conventional control systems performance often proves to be poor. However, there a hybrid fuzzy PID control logic, whose tuning parameters are provided in real time. The fuzzy controller tuning is made on the basis of Mamdani controller, also exploiting the results coming from an identification procedure that is carried on when an unmeasured step disturbance of any shape affects the process behaviour. This paper presents procedure for identifying technological object control in a closed loop, i. e. that operates the automated control system. The variation in the controlled variable, caused by the change of the nonmeasurable disturbance, is considered the initial signal for the identification procedure. The parameters of the control object are found by optimization method Levenberg-Marquardt

Dynamic simulation of uranyl nitrate crystallization process

The paper addresses the dynamic modeling of the uranyl nitrate crystallization process. The paper is filling the gap of the current literature in the regeneration of nuclear fuel, improvement of the process understanding, and future needs in controllability and operability for safety purposes to obtain a final product of the process in the pure state. Basing on the existing kinetic studies on uranium crystallization, a novel mathematical model of the uranyl nitrate crystallization process is proposed describing the heat and mass transfer phenomena. Sensitivity analyses are provided for the prediction of the main outlet parameters of the crystallization process and to improve the process design for enhanced operational flexibility

Cellular automata application for simulation of uranium crystallization process

The paper addresses the dynamic modelling of the UNH crystal growth by means of cellular automata(CA) method for nuclear fuel reprocessing as the alternative to traditionally used extraction method. Model-based CA approach is considered to predict dependence of product's properties on input changes: uranium and nitric acid concentration, solution temperature. CA approach is preferable for crystallization process to get a high purity of reprocessed materials. C++ application is developed as a result of the research. The application allows monitoring of dynamics changes of solution temperature, uranium concentration and shape of crystals

Effect of MSCs and MSC-Derived Extracellular Vesicles on Human Blood Coagulation

Mesenchymal stem cells (MSCs) have emerged as a potent therapeutic tool for the treatment of a number of pathologies, including immune pathologies. However, unwelcome effects of MSCs on blood coagulation have been reported, motivating us to explore the thrombotic properties of human MSCs from the umbilical cord. We revealed strong procoagulant effects of MSCs on human blood and platelet-free plasma using rotational thromboelastometry and thrombodynamic tests. A similar potentiation of clotting was demonstrated for MSC-derived extracellular vesicles (EVs). To offer approaches to avoid unwanted effects, we studied the impact of a heparin supplement on MSC procoagulative properties. However, MSCs still retained procoagulant activity toward blood from children receiving a therapeutic dose of unfractionated heparin. An analysis of the mechanisms responsible for the procoagulant effect of MSCs/EVs revealed the presence of tissue factor and other proteins involved in coagulation-associated pathways. Also, we found that some MSCs and EVs were positive for annexin V, which implies the presence of phosphatidylserine on their surfaces, which can potentiate clot formation. Thus, we revealed procoagulant activity of MSCs/EVs associated with the presence of phosphatidylserine and tissue factor, which requires further analysis to avoid adverse effects of MSC therapy in patients with a risk of thrombosis