Thermophysical Properties Enhancement in Construction Materials Based on Cement and Plaster

Enhancing insulating power of buildings envelope saves energy costs and minimizes associated CO2 emissions. The development of materials with good thermal performance is a major challenge. This work shows the effect of incorporating different additions on the thermal properties of composites based on plaster and cement through a series of experiments. The additives used are among the most widespread wastes in Morocco. Dozens of new samples based on cement and plaster have been prepared and experimentally characterized by the box method to develop environmentally friendly materials with the best thermal characteristics. The results show that increasing incorporation rate of additives significantly improves thermophysical properties of based materials. The addition of 4% alfa and 6% of coffee grounds in plaster matrix and the replacement of cement by 50% of ashes in mortar and concrete record the low thermal properties including thermal conductivity, diffusivity, effusivity and specific heat. The good performance of new materials encourages us to integrate them into the building envelope. The results of the annual simulations carried out for a typical building located in Meknes indicated that the use of these proposed materials has significant economic and environmental benefits. A reduction of 50% in energy and a limitation of 3029.13 kgCO2eq/yr are observed thanks to an effective combination between the developed material

Real Time Weed Detection using a Boosted Cascade of Simple Features

Weed detection is a crucial issue in precision agriculture. In computer vision, variety of techniques are developed to detect, identify and locate weeds in different cultures. In this article, we present a real-time new weed detection method, through an embedded monocular vision. Our approach is based on the use of a cascade of discriminative classifiers formed by the Haar-like features. The quality of the results determines the validity of our approach, and opens the way to new horizons in weed detection

A Fast and Efficient Shape Descriptor for an Advanced Weed Type Classification Approach

In weed management, the distinction between monocots and dicots species is an important issue. Indeed, the yield is much higher with the application of a selective treatment instead of using a broadcast herbicide overall the parcel. This article presents a fast shape descriptor designed to distinguish between these two families of weeds. The efficiency of the descriptor is evaluated by analyzing data with the pattern recognition process known as the discriminant factor analysis (DFA). Excellent results have been obtained in the differentiation between these two weed specie

Active Vibration Control of Timoshenko Sigmoid Functionally Graded Porous Composite Beam with Distributed Piezoelectric Sensor/Actuator in a Thermal Environment

This work presents the study of the dynamics and active control of a cantilever sigmoid FGM beam with porosities in a thermal environment. During this study, we considered the Timoshenko beam’s theory combined with the finite element method (FEM). This work also presents a comparative study with an experimental study for the vibration of a functionally graded piezoelectric beam (FGPM) to validate the numerical model. Linear quadratic Gaussian (LQG) optimal control with a Kalman filter was used for the vibration control using piezoelectric sensors and actuators as symmetrical layers to eliminate membrane effects. The controlled and uncontrolled responses are presented, considering the influence of thermal effect, the porosity of the FGM material, and the location of the sensor pair on the smart structure. The results indicate that the porosity effect of the FGM material, as well as the application of the thermal effect, involves an increase in vibration frequencies, in contrast to the increase in the power law index. The study also shows that the thermal and porosity effects result in an increase in vibration amplitudes

Roughness effects of textured surfaces in hydrodynamic lubrication

Several studies have been conducted to improve and model the lubricated contact between surfaces. The main subjects were defining the hydrodynamic parameters to reduce energy losses and protect the environment. Some of the proposed models have studied the effect of textures in hydrodynamic lubrication and have proved that adapted shapes and geometries can improve the performance of lubricated contacts. A hydrodynamic model was developed by assuming the roughness of the textured surface and considering the cavitation in a steady-state regime. The proposed model was validated and compared with the analytical model of Fowell et al. [1]. Three different textures shapes were considered. The results showed that the rough-textured thrust affects the hydrodynamic performance significantly. Thus, by increasing the arithmetic roughness of textured surfaces, the hydrodynamic pressure, and the lifting force increase depending on the texture shape. A rougher surface slightly increases the friction force for the three considered textures

Finite Element Model of Vibration Control for an Exponential Functionally Graded Timoshenko Beam with Distributed Piezoelectric Sensor/Actuator

This paper presents a dynamic study of sandwich functionally graded beam with piezoelectric layers that are used as sensors and actuators. This study is exploited later in the formulation of the active control laws, while using the optimal control Linear Quadratic Gaussian (LQG), accompanied by the Kalman filter. The mathematical formulation is based on Timoshenko’s assumptions and the finite element method, which is applied to a flexible beam divided into a finite number of elements. By applying the Hamilton principle, the equations of motion are obtained. The vibration frequencies are found by solving the eigenvalue problem. The structure is analytically then numerically modeled and the results of the simulations are presented in order to visualize the states of their dynamics without and with active control

Robust Control and Thermal Analysis of a Reduced Model of Kirchhoff Composite Plate with Random Distribution of Thermopiezoelectric Sensors and Actuators

This paper presents an implementation of a robust control LQG-Kalman model applied to composite Kirchhoff plate dynamics. A reduced model of a finite element method and control procedure is considered in the modeling of a structure because of the important number of piezoelectric patches used in control. Replacing the full model with a short model reduces the computational and time costs, especially when the number of degrees of freedom is significant. In robust control, the measurement of all states is not necessary and the observability and estimability criteria can be exploited, while conventional LQR control assumes that the data accessibility of all states is available. For this reason, robust control is proposed to control the random external disturbances and is compared to LQR control to illustrate its practicability and efficiency. The sensors and actuators in the thermo-piezoelectric material are randomly distributed on both sides of the plate to establish the control procedure. A Monte Carlo simulation is used in the selection of the degrees of freedom of sensors presenting high electrical outputs. Numerical simulations are performed to demonstrate the effectiveness of the proposed control procedure in a reduced model and under mechanical and thermal disturbances in comparison with the LQR control

Robust Control and Thermal Analysis of a Reduced Model of Kirchhoff Composite Plate with Random Distribution of Thermopiezoelectric Sensors and Actuators

This paper presents an implementation of a robust control LQG-Kalman model applied to composite Kirchhoff plate dynamics. A reduced model of a finite element method and control procedure is considered in the modeling of a structure because of the important number of piezoelectric patches used in control. Replacing the full model with a short model reduces the computational and time costs, especially when the number of degrees of freedom is significant. In robust control, the measurement of all states is not necessary and the observability and estimability criteria can be exploited, while conventional LQR control assumes that the data accessibility of all states is available. For this reason, robust control is proposed to control the random external disturbances and is compared to LQR control to illustrate its practicability and efficiency. The sensors and actuators in the thermo-piezoelectric material are randomly distributed on both sides of the plate to establish the control procedure. A Monte Carlo simulation is used in the selection of the degrees of freedom of sensors presenting high electrical outputs. Numerical simulations are performed to demonstrate the effectiveness of the proposed control procedure in a reduced model and under mechanical and thermal disturbances in comparison with the LQR control

Influence of the mixing water rate on the plaster thermo physical properties: Experimental and dynamic study

The construction industry has long been one of the most energy intensive sectors in the world. Therefore, the development of building materials appears to be one of the effective solutions to this challenge. Plaster is considered among the materials widely used in construction because of its advantageous properties. The present article includes in its entirety two sequential studies. The first one, deals with an experimental analysis of the plaster thermo-physical properties formed by two different mixing water rates, in order to evaluate its effect. While, the second, presents a dynamic simulation results of an individual building subjected to different climatic conditions of Morocco and in which no energy efficiency measures were carried out, through simulations series realized by using TRNSYS software. The latter study was intended to quantify the developed materials impact, on the energy required to maintain the occupants comfort. The findings obtained in this work, revealed the positive influence of increasing the mixing water rate. Thus, reducing the plaster thermo-physical properties, delaying the heat transmission, and significantly decreasing the building energy consumption devoted to heating and cooling

Analysis and management of risks related to TDG in Morocco using the FMEAC approach

Road transport of dangerous goods is the most accidental mode of transport, which can have an impact on the environment, including air pollution, global climate issues of concern, noise pollution, water pollution, accidents, land use and habitat fragmentation. The objective of this study is to manage the risks associated with Moroccan road transport from an environmental point of view while taking into account the collaborative aspect at the level of a logistics chain. In this regard, the use of a problem-solving approach such as FMECA to identify anomalies and malfunctions that may lead to failure. It consists in analysing the failure modes, their effects and their criticality. This approach is based on four main criteria: severity, frequency, non-detection and criticality