The effect of thermal treatment on the properties of expanded polystyrene

Expanded polystyrene (EPS) is a commonly used polymer in the packaging industry and for the thermal insulation of buildings. It has poor mechanical properties which limit its application in some areas. A heat treatment was carried out on a sample of EPS, in order to improve its mechanical properties. The treatment consists of operations that combine the heating and cooling of the material. It is executed to improve the characteristics of the treated polymer and make it more favourable for use in new applications. In the case of EPS, this process changes the behaviour of the polymer in a beneficial manner and maximizes its density and hardness. Indeed, the treated version shows interesting mechanical, tribological and hygroscopic properties. This improvement was obtained mainly due to the morphological modification of the structure of EPS. Indeed, heat treatment leads to the creation of a polystyrene crust which covers every EPS bead. This crust protects the cell structure of each bead against stretching and supports most of the load applied to the treated version of EPS. Thus, the treated EPS can be used not only for packaging and thermal insulation but also for more structural applications

Variation in physicochemical and sensory quality of sour orange (

Introduction. Citrus aurantium L. sour oranges are poorly exploited in Tunisia, although the Tunisian Cap Bon is one of the major areas of production of sour orange trees. Our study aimed at determining the effect of the geographic origin of the raw material on quality of orange marmalades and consumer acceptance. Materials and methods. Fresh sour oranges were collected from five areas in the Cap Bon region in the North-East of Tunisia for producing marmalades. Physicochemical characterisation of marmalades from the five different origins included the determination of soluble solids, total and volatile acidity, the measurement of reducing sugars, and measurement of colour. Sensory panels from Tunisia, Algeria and Europe revealed the marmalades’ sensory profiles. The sensory panels then attributed preference and acceptance ranks for the five marmalades. Results and discussion. The analyses highlighted an effect of the geographic origin of the raw material on the physicochemical quality. The most suitable geographic conditions seem to be climatic and edaphic criteria. Assessors from various nationalities revealed different sensory profiles depending on the consumer’s nationality and fruit production region. In addition, Tunisian consumers are less likely to be marmalade buyers than European and Algerian consumers

Decay rate performance approach for stabilization continuous fuzzy models using their discretized forms

International audiencePurpose – The purpose of this paper is to deal with the stabilization of the continuous Takagi Sugeno (TS) fuzzy models using their discretized forms based on the decay rate performance approach. Design/methodology/approach – This approach is structured as follows: first, a discrete model is obtained from the discretization of the continuous TS fuzzy model. The discretized model is obtained from the Euler approximation method which is used for several orders. Second, based on the decay rate stabilization conditions, the gains of a non-PDC control law ensuring the stabilization of the discrete model are determined. Third by keeping the values of the gains, the authors determine the values of the performance criterion and the authors check by simulation the stability of the continuous TS fuzzy models through the zero order hold. Findings – The proposed idea lead to compare the performance continuous stability results with the literature. The comparison is, also, taken between the quadratic and non-quadratic cases. Originality/value – Therefore, the originality of this paper consists in the improvement of the continuous fuzzy models by using their discretized models. In this case, the effect of the discretization step on the performances of the continuous TS fuzzy models is studied. The usefulness of this approach is shown through two examples

Nonquadratic Lyapunov function for continuous TS fuzzy models through their discretization

[IF=1.986]International audienceSince the beginning of the fuzzy control theory, results have been obtained independently for continuous and discrete models. It is still quite difficult to use nonquadratic Lyapunov functions for the continuous case, while this is much easier for the discrete case. This approach tries to put a bridge between the continuous and discrete cases for the class of continuous Takagi Sugeno fuzzy models that can be exactly discretized. Indeed, for this particular class, once the stability of the discrete model is ensured, the same control law applied to the continuous model will ensure the stability too. The interest of such an approach is that complex control laws and complex Lyapunov functions can be easily used. Simulation examples show that stabilizing feedbacks may be obtained with discrete control laws when purely continuous ones fail

Artificial Intelligence-Based Diabetes Diagnosis with Belief Functions Theory

We compared various machine learning (ML) methods, such as the K-nearest neighbor (KNN), support vector machine (SVM), and decision tree and deep learning (DL) methods, like the recurrent neural network, convolutional neural network, long short-term memory (LSTM), and gated recurrent unit (GRU), to determine the ones with the highest precision. These algorithms learn from data and are subject to different imprecisions and uncertainties. The uncertainty arises from the bad reading of data and/or inaccurate sensor acquisition. We studied how these methods may be combined in a fusion classifier to improve their performance. The Dempster–Shafer method, which uses the formalism of belief functions characterized by asymmetry to model nonprecise and uncertain data, is used for classifier fusion. Diagnosis in the medical field is an important step for the early detection of diseases. In this study, the fusion classifiers were used to diagnose diabetes with the required accuracy. The results demonstrated that the fusion classifiers outperformed the individual classifiers as well as those obtained in the literature. The combined LSTM and GRU fusion classifiers achieved the highest accuracy rate of 98%

On the definition of non quadratic Lyapunov function for continuous Takagi Sugeno fuzzy models through their discretized forms

International audienceSince a few years, LMIs conditions associated to the control of continuous Takagi Sugeno (TS) fuzzy models have used non quadratic Lyapunov functions. Indeed they are much more general than classical quadratic functions. However, there are requirements about the derivative of the membership functions appearing in the LMIs. Whereas, this problem doesn't exist with discrete time models. This study tries to put a bridge between the continuous and discrete cases for the class of continuous Takagi Sugeno fuzzy models which can be exactly discretized. Indeed, for this particular class, ones the stability of the discrete model is ensured, the same control law applied to the continuous model will ensure the stability too. The interest of such an approach is that complex control laws can be applied with no hypothesis on the membership functions. Simulation examples illustrate the effectiveness of the proposed approach

Continuous Stability TS Fuzzy Systems Novel Frame Controlled by a Discrete Approach and Based on SOS Methodology

Generally, the continuous and discrete TS fuzzy systems’ control is studied independently. Unlike the discrete systems, stability results for the continuous systems suffer from conservatism because it is still quite difficult to apply non-quadratic Lyapunov functions, something which is much easier for the discrete systems. In this paper and in order to obtain new results for the continuous case, we proposed to connect the continuous with the discrete cases and then check the stability of the continuous TS fuzzy systems by means of the discrete design approach. To this end, a novel frame was proposed using the sum of square approach (SOS) to check the stability of the continuous Takagi Sugeno (TS) fuzzy models based on the discrete controller. Indeed, the control of the continuous TS fuzzy models is ensured by the discrete gains obtained from the Euler discrete form and based on the non-quadratic Lyapunov function. The simulation examples applied for various models, by modifying the order of the Euler discrete fuzzy system, are presented to show the effectiveness of the proposed methodology

Continuous Stability TS Fuzzy Systems Novel Frame Controlled by a Discrete Approach and Based on SOS Methodology

Generally, the continuous and discrete TS fuzzy systems’ control is studied independently. Unlike the discrete systems, stability results for the continuous systems suffer from conservatism because it is still quite difficult to apply non-quadratic Lyapunov functions, something which is much easier for the discrete systems. In this paper and in order to obtain new results for the continuous case, we proposed to connect the continuous with the discrete cases and then check the stability of the continuous TS fuzzy systems by means of the discrete design approach. To this end, a novel frame was proposed using the sum of square approach (SOS) to check the stability of the continuous Takagi Sugeno (TS) fuzzy models based on the discrete controller. Indeed, the control of the continuous TS fuzzy models is ensured by the discrete gains obtained from the Euler discrete form and based on the non-quadratic Lyapunov function. The simulation examples applied for various models, by modifying the order of the Euler discrete fuzzy system, are presented to show the effectiveness of the proposed methodology