Application of multi-model control with fuzzy switching to a micro hydro-electrical power plant

Modelling hydraulic turbine generating systems is not an easy task because they are non-linear and uncertain where the operating points are time varying. One way to overcome this problem is to use Takagi–Sugeno (TS) models, which offer the possibility to apply some tools from linear control theory, whereas those models are composed of linear models connected by a fuzzy activation function. This paper presents an approach to model and control a micro hydro power plant considered as a non-linear system using TS fuzzy systems. A TS fuzzy system with local models is used to obtain a global model of the studied plant. Then, to combine efficiency and simplicity of design, PI controllers are synthesised for each considered operating point to be used as conclusion of an electrical load TS Fuzzy controller. The latter ensures the global stability and desired performance despite the change of operating point. The proposed approach (model and controller) is tested on a laboratory prototype, where the obtained results show their efficiency and their capability to ensure good performance despite the non-linear nature of the plant.     

Inverse neural network for optimal performance in polygeneration systems

In this paper, inverse neural network (ANNi) is applied to optimization of operating conditions or parameters in energy processes. The proposed method ANNi is a new tool which inverts the artificial neural network (ANN), and it uses a Nelder-Mead optimization method to find the optimum parameter value (or unknown parameter) for a given required condition in the process. In order to accomplish the target, first, it is necessary to build the artificial neural network (ANN) that simulates the output parameters for a polygeneration process. In general, this class of ANN model is constituted of a feedforward network with one hidden layer to simulate output layer, considering well-known input parameters of the process. Normally, a Levenberg–Marquardt learning algorithm, hyperbolic tangent sigmoid transfer-function, linear transfer-function and several neurons in the hidden layer (due to the complexity of the process) are considered in the constructed model. After that, ANN model is inverted. With a required output value and some input parameters it is possible to calculate the unknown input parameter using the Nelder-Mead algorithm. ANNi results on three different applications in energy processes showed that ANNi is in good agreement with target and calculated input data. Consequently, ANNi is applied to determine the optimal parameters, and it already has applications in different processes with a very short elapsed time (seconds). Therefore, this methodology can be useful for the controlling of engineering processes.     

Synthesis of new silica xerogels based on bi-functional 1,3,4-thiadiazole and 1,2,4-triazole adducts

New transparent Silica-based hybrid materials were synthesized by reaction of polymethylhydrosiloxane (PMHS) and organic compounds: 1,3,4-thiadiazole-2,5-diamine (1), 1,3,4-thiadiazole-2,5-dithiol (2) and 1H-1,2,4-triazole-3-thiol (3), in tetrahydrofuran as solvant using hexachloroplatinic acid (H₂PtCl₆.6H₂O) as a catalyst. PMHS was used as a principal network forming agent, it has been cross-linked via hydrosilylation reaction with bi-functional heterocyclic compounds, leading to the formation of colored gels. These later dried (xerogels) were characterized by numerous techniques, including spectroscopy of (FT–IR) and ¹³C and ²⁹Si CP MAS NMR. The xerogels morphology and texture were studied by scanning electron microscopy and Brunauer–Emmet–Teller method. According to N₂-physisorption results, isotherms are classified as type IV with H₂ type hysteresis loop; then, the xerogels are mesoporous materials. The optic and magnetic properties of the obtained materials were studied by UV–VIS and EPR spectroscopies, respectively. This study showed that all materials are paramagnetic semiconductors.     

Adsorption effect on the successive ionic layer adsorption and reaction technique

We carried out a series of experiments of metal sulfide deposition on glass and copper substrates by the successive ionic layer adsorption and reaction (SILAR) technique. This technique based on the cations adsorption process involves the presence of the van der Waals and electrostatic forces. According to the theoretical study discussed herein, the equilibrium separation between cations and the substrate surface was lower in the case of a copper substrate than that of a glass one confirming the observed experiments results obtained by the SILAR technique. The surface charge of the glass substrate is strongly dependent on the solution pH. In the absence of the surface charge, the dominant forces between cations in solution and the glass substrate were repulsive in contrast with the case of the copper substrate in which attractive forces dominate even if the surface is somewhat positively charged. This study enriches the knowledge on the optimization parameters for fabricating thin films of metal chalcogenide of good adherence.     

Influence of iron doping on morphological,structural and optical properties of zinc oxide thin films prepared by dip-coating method

Undoped zinc oxide and iron-doped zinc oxide thin films have been deposited by the sol-geldipcoating method. The Fe/Zn nominal volume ratio was 5% in the solution. The effects of Fe incorporation on morphological, structural, and optical properties of ZnO films were investigated. The scanning electron microscopy measurements showed that the surface morphology of the prepared thin films was affected by Fe doping. The X-ray diffraction patterns of the thin films showed that doped incorporation leads to substantial changes in the structural characteristics of ZnO thin films. The optical absorption measurements indicated a band gap in the range of 3.31 to 3.19 eV. The X-ray photoelectron spectroscopy demonstrated that Fe is incorporated in the ZnO matrix with 6.5 atomic percent (at %). The energy dispersive spectroscopy studies indicated the formation of ZnO with high efficiency.     

Error propagation on COP prediction by artificial neural network in a water purification system integrated to an absorption heat transformer

Numerous authors have reported heat transfer prediction using artificial neural network (ANN). However, the precision or accuracy of the calculation is generally unknown. Error propagation from Monte Carlo method is applied to the coefficient of performance (COP) predicted by ANN. This COP permitted us to evaluate a water purification process integrated into a heat transformer. A feedforward network with a hidden layer was used in order to obtain error propagation in COP prediction. This model used the input and output-temperatures for each component (absorber, generator, evaporator, and condenser), as well as two pressure parameters from the absorption heat transformer and LiBr + H₂O mixture with different LiBr concentrations. The hyperbolic tangent sigmoid transfer-function and the linear transfer-function were used for the network. A new correlation for calculating relative standard deviation (%RSD_COP) of COP as a function of COP_EXP and %RSD_instrument was obtained. This study shows that %RSD_COP of ANN prediction decreased when the experimental COP is increased. The range of COP operations was from 0.21 to 0.39.     

A fuzzy rule base for the improved control of a pressurized waternuclear reactor

In France, nuclear energy provides about 80% of the whole electricity production. A modulation of the nuclear power plants must be able to respond to the demand on the network. The pressurized water nuclear reactor has to yield correctly a load set point. Fundamentally, two parameters are concerned in leading this task to a successful conclusion: the power axial-offset and the control rods position. The focus of this study is the automation of the control of the power axial-offset by adding soluble boron and by minimizing the volume flows through the water pump. It is also important to take into consideration the liquid waste volume. Water or boron is injected into the reactor primary circuit. At the present time this task is still performed manually by an operator, for all previous attempts to automate it failed. A nonfuzzy device, earlier developed by Electricite de France, was intensively tested at Cruas, France, power plant and allowed us to prove the feasibility of automating the boration-dilution function. But it could not be definitely adopted because it was too difficult to be tuned for industrial purposes. That device, sketchily described in the paper, gave rise to the development of a real-time fuzzy controller for the power axial-offset and the control rods insertion in a pressurized water reactor (PWR). The fuzzy controller, which is the main subject of the paper, expresses more naturally the human expertise, thus avoiding the previous issue of empirical tunings. It was implemented in simulation using Matlab-Simulink on a Sun workstation. Two realistic tests discussed show that the fuzzy controller runs as efficiently as an expert operator does     

A Study of the Fractionation Dose Effect on the Radiation Response of Windose B3 Dosimeter

Windose B3 dosimeters have been investigated using UV–vis spectrophotometry to determine the impact of the frequent interruptions during gamma irradiation on the absorbed dose. To achieve this purpose, a set of experiments were conducted by examining the behavior of these dosimeters as result of these accidents. Experiments were conducted based on varying four influencing factors: the storage temperature, the number of fractions, the total delivered dose and the storage time. The chosen parameters (dose and fraction time) are selected from pre-studies and in accordance with conditions of industrial irradiation. The obtained results for one fraction or five fractions had bigger specific absorbance than the dosimeters receiving its dose without fractionation and that the effect of five fractions on the response of dosimeters is more significant than the effect of one fraction. The most important over response (15%) is obtained for 10 kGy as absorbed dose with five fractions, 40 °C as a storage temperature, and 24 h as storage time. The influence quantities have an effective effect on the Windose B3 dosimeter response and suitable corrections are indispensable.