Control of a non-isothermal continuous stirred tank reactor by a feedback–feedforward structure using type-2 fuzzy logic controllers

A control system that uses type-2 fuzzy logic controllers (FLC) is proposed for the control of a non-isothermal continuous stirred tank reactor (CSTR), where a first order irreversible reaction occurs and that is characterized by the presence of bifurcations. Bifurcations due to parameter variations can bring the reactor to instability or create new working conditions which although stable are unacceptable. An extensive analysis of the uncontrolled CSTR dynamics was carried out and used for the choice of the control configuration and the development of controllers. In addition to a feedback controller, the introduction of a feedforward control loop was required to maintain effective control in the presence of disturbances. Simulation results confirmed the effectiveness and the robustness of the type-2 FLC which outperforms its type-1 counterpart particularly when system uncertainties are present

Type-2 Fuzzy Control of a Bioreactor

Abstract—In this paper the control of a bioprocess using an adaptive type-2 fuzzy logic controller is proposed. The process is concerned with the aerobic alcoholic fermentation for the growth of Saccharomyces Cerevisiae a n d i s characterized by nonlinearity and parameter uncertainty. Three type-2 fuzzy controllers heve been developed and tested by simulation: a simple type-2 fuzzy logic controller with 49 rules; a type-2 fuzzyneuro- predictive controller (T2FNPC); a t y p e -2 selftuning fuzzy controller ( T2STFC). The T2FNPC combines the capability of the type-2 fuzzy logic to handle uncertainties, with the ability of predictive control to predict future plant performance making use of a neural network model of the non linear system. In the T2STFC the output scaling factor is adjusted on-line by fuzzy rules according to the current trend of the controlled process. T h e advantage of the proposed adaptive algorithms is to greatly decrease the number of rules needed for the control reducing the computational load and at same time assuring a robust control

Adaptive Type-2 Fuzzy Logic Control of a Bioreactor

Two adaptive type-2 fuzzy logic controllers with minimum number of rules are developed and compared by simulation for control of a bioreactor in which aerobic alcoholic fermentation for the growth of Saccharomyces cerevisiae takes place. The bioreactor model is characterized by nonlinearity and parameter uncertainty. The first adaptive fuzzy controller is a type-2 fuzzy-neuro-predictive controller (T2FNPC) that combines the capability of type-2 fuzzy logic to handle uncertainties, with the ability of predictive control to predict future plant performance making use of a neural network model of the nonlinear system. The second adaptive fuzzy controller is instead a self-tuning type-2 PI controller, where the output scaling factor is adjusted online by fuzzy rules according to the current trend of the controlled process. The performance of a type-2 fuzzy logic controller with 49 rules is used as reference

Non linear control of glycaemia in type 1 diabetic patients

A fuzzy controller for the closed loop control, by insulin infusion of glycaemia in type 1 diabetic patients is proposed. The controller uses type-2 fuzzy sets. The controller was tested in simulation using a complex nonlinear model of the glucose metabolism. Simulation results confirm the effectiveness and the robustness of the type-2 fuzzy logic controller. The design of the controller uses an optimization method based on genetic algorithms. This makes the type-2 fuzzy controller more efficient and faster than a fuzzy controller with type-1 fuzzy sets, allowing a more accurate control of the glucose in the blood

Solution to Agricultural Machinery Powering Problems Using DIY Photovoltaics

The contribution of this work is the realization and the field testing of a photovoltaic system in agriculture following the Do-It-by-Yourself (DIY) approach, i.e., a system easy to be assembled from commercially available components, portable off-site and recharging the battery directly when working. This solution allows the daily work of a simple agricultural machine to be carried out with the advantage of no interruption and, in addition, the saving of any electricity cost associated to battery recharging. The design and the realization of the DIY photovoltaic apparatus are described, which turns out quite cheap. The resulting economic advantages are analyzed, with reference to a geographical collocation and the typical agricultural practice in Sicily

Sutureless jejuno-jejunal anastomosis in gastric cancer patients: a comparison with handsewn procedure in a single institute

Background: The biofragmentable anastomotic ring has been used to this day for various types of anastomosis in the gastrointestinal tract, but it has not yet achieved widespread acceptance among surgeons. The purpose of this retrospective study is to compare surgical outcomes of sutureless with suture method of Roux-and-Y jejunojejunostomy in patients with gastric cancer.Methods: Two groups of patients were obtained based on anastomosis technique (sutureless group versus hand sewn group): perioperative outcomes were recorded for every patient.Results: The mean time spent to complete a sutureless anastomosis was 11 +/- 4 min, whereas the time spent to perform hand sewn anastomosis was 23 +/- 7 min. Estimated intraoperative blood loss was 178 +/- 32ml in the sutureless group and 182 +/- 23ml in the suture-method group with no significant differences. No complications were registered related to enteroanastomosis. Intraoperative mortality was none for both groups.Conclusions: The Biofragmentable Anastomotic Ring offers a safe and time-saving method for the jejuno-jejunal anastomosis in gastric cancer surgery, and for this purpose the ring has been approved as a standard method in our clinic. Nevertheless currently there are few studies on upper gastrointestinal sutureless anastomoses and this could be the reason for the low uptake of this device

Comparison of the 6th and 7th editions of the AJCC/UICC TNM staging system for gastric cancer focusing on the "N" parameter-related survival: the monoinstitutional NodUs Italian study

Background: A large number of Asian population studies examined the difference between the 6th and the 7th tumor, node, metastasis (TNM) while it is still poorly validated among Caucasian populations. This is a retrospective study aimed at investigating the efficacy of the 7th edition American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) staging system for gastric cancer focusing on the "N" parameter-related survival for prognostic assessment in gastric cancer patients of a single Western high-volume institution.Methods: From January 2002 to December 2009, the data of 274 patients with gastric cancer who underwent gastric surgery at the 8th General and Gastrointestinal Surgical Centre of the Second University of Naples were analyzed retrospectively. We collected data for patient demographics, tumor characteristics, surgical characteristics, and TNM stage. Particularly, the nodal status, with the number of dissected nodes and metastatic nodes, was reviewed from the pathology records. The same patient dataset was used to stage patients according to both the 6th and 7th edition criteria.Results: Age at surgery, tumor location, histological grade, Lauren's classification subtypes, and 6th and 7th AJCC/UICC N categories were found to have statistically significant associations with overall survival on univariate analysis. In the 6th edition staging system, the Kaplan-Meier plot did not show significant overlapped survival curves: significant differences were found between N0 and N1, P<.001; N1 and N2, P=.04; and N2 and N3, P<.001. On the contrary, in the 7th edition, among all five substages, there were similar survival curves between N categories 2 and 3a (P=.98) with a statistically significant discriminatory ability only between N1 versus N3b and N2 versus N3b (P=.02 and .04, respectively).Conclusions: Based on analysis, we found that several clinicopathological variables, especially histological grade and Lauren's classification, were significant prognostic factors in our database. The 6th and 7th AJCC/UICC N classifications represent significantly independent prognostic factors, and the 6th AJCC/UICC N classification seems to be superior to the 7th AJCC/UICC N classification in terms of uniformity, differentiation, and monotonicity of gradients

Application of fuzzy control to residential cogeneration with renewable energy sources

A fuzzy PI controller and a conventional PI controller were adopted to develop control for a residential cogeneration system made by a biomass-fired and solar-powered fluidized bed prototype. Its mathematical model is characterized by nonlinearities and, more important, by uncertainty and variability in parameters. The paper describes in detail the PI fuzzy controller, the development of which was based on the knowledge of the continuity diagrams of the process model. Then, the paper reports a comparison in simulation between the PI fuzzy controller and the conventional PI one. The PI fuzzy controller exhibits a superior performance, as far as both robustness and rate of response. As a result, the adoption of a PI fuzzy controller turns out the best choice for this residential cogeneration system and a favorable option for nonlinear processes with uncertain or time-varying parameters

Software-assisted study of a non-linear polymerization reactor control by IBSE approach

This paper provides a contribution to the application of an innovative approach, the IBSE method, to the study of automatic control in process systems within a Chemical Engineering master course, with reference to a class of 28 students. The paper describes in detail the implementation of the five phases making up the IBSE method, from the engagement to the final evaluation, to a case study focusing the simulation of the non-linear dynamics and automatic control of a continuous polymerization reactor