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Temperature Control System (temperature + control_system)

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Engineering50%

Selected Abstracts

Nonlinear Laguerre,Volterra observer-controller and its application to process control

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2010
Hai-Tao Zhang
Abstract By expanding each kernel using the orthonormal Laguerre series, a Volterra functional series is used to represent the input/output relation of a nonlinear dynamic system. With the feedback of the modeling error, we design a novel nonlinear state observer, based on which an output feedback controller is derived for both the stabilization and tracking problems. The stability of the closed-loop system is analyzed theoretically. The algorithm is effectively applied on the continuous stirring tank reactor and chemical reactor temperature control system. Copyright © 2009 John Wiley & Sons, Ltd. [source]

How to optimize the TS-fuzzy knowledge base to achieve desired performances: Accuracy and robustness

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 1 2008
A. Soukkou
Abstract Designing an effective criterion/learning to find the best rule and optimal structure is a major problem in the design process of fuzzy neural controller. In this paper, we introduce a new robust model of Takagi Sugeno fuzzy logic controller. A hybrid learning algorithm, called hybrid approach to fuzzy supervised learning (HAFSL), which combines the genetic algorithm (GA) and gradient descent technique (GD) is proposed for constructing an efficient and robust fuzzy neural network controller (FNNC). Two phases of design and learning process are presented in this work. A GA is used for finding near optimal structure/parameters of the FNNC that minimizes the number of rules (initialization procedure). The second stage of learning algorithm uses the backpropagation algorithm based on GD method to fine tune the consequent parameters of the controller. The genes of chromosome are arranged into two parts, the first part contains the control genes (the certainty factors) and the second part contains the parameters genes that representing the fuzzy knowledge base. The effectiveness of this chromosome formulation enables the fuzzy sets and rules to be optimally reduced. The performances of the HAFSL are compared to these found by the traditional PI with genetic optimization (GA-PI). Simulations demonstrate that the proposed HAFSL and GA-PI algorithms have good generalization capabilities and robustness on the water bath temperature control system. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Monitoring epoxy and unsaturated polyester reactions under pressure,Reaction rates and mechanical properties

POLYMER ENGINEERING & SCIENCE, Issue 11 2009
Javier C. Cruz
The effects of pressure on reaction rates and final mechanical properties were studied for an unsaturated polyester (UP) and epoxy resin. A pressure chamber where reactions can be monitored by use of Raman spectroscopy has been built for these purposes. The chamber allows for pressures up to 13.8 MPa at 200°C. An advanced temperature control system has been adapted to the vessel to precisely control and monitor sample temperature variations and overshoots. It is described how for an accelerated UP reaction increasing pressure will result in a competing effect on the reaction rate where the rate will initially lower, but with increased pressures it may accelerate due to acceleration of the reaction rate constants. The final mechanical properties exhibit a similar behavior slightly increasing with pressure but lowering as pressure is raised further. For epoxy, it was shown that the reaction kinetics were accelerated by pressure although no mechanical property differences could be noted for the pressure ranges tested. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers. [source]

Haematological response and growth performance of Nile tilapia (Oreochromis niloticus L.) fed diets containing folic acid

AQUACULTURE RESEARCH, Issue 8 2009
Margarida Maria Barros
Abstract Haematological response and growth performance over 150 days, and resistance to a low-temperature stress of Nile tilapia fed diets with increasing folic acid (FA) levels were evaluated. The experiment was conducted in a completely randomized design with eight FA levels (0.0, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 mg kg,1 feed) supplemented in purified diets (32.0% CP and 13 398 kj DE kg,1). One hundred and ninety-two fingerlings were randomly assigned to 32 net cages distributed in eight 1000 L aquaria with a physical and biological filter and a temperature control system (26.0 ± 1.0 °C). For cold-induced stress, fish were transferred to 24 30 L-aquaria with individual biofilters and aeration. The water temperature was gradually reduced until it reached 13 °C. Haematological parameters evaluated before and after cold stress were total erythrocytes and leucocytes count, differential leucocyte, haemoglobin, haematocrit, total plasmatic protein and haematometric indices. Growth performance parameters were mean weight gain, feed conversion ratio and survival. Dietary FA supplementation did not influence erythropoiesis under normal temperature conditions; cold stress impaired erythropoiesis, causing hypochromic microcytic anaemia and leucopoiesis, and also neutrophilia. Growth performance is influenced by folate and supplementation between 0.5 and 1.0 mg FA kg,1 diet, which makes up for nutritional demands, guaranteeing production and health under appropriate temperature conditions. [source]