Modeling of the Behavior of Expansive Soils

In the preliminary reconnaissance phase and once the swelling of soil is suspected, it is possible to obtain an estimation of swelling parameters (amplitude and pressure) using numerous rheological models proposed in the literature. These models relate the parameters of swelling to the geotechnical parameters determined from mechanical tests. The analysis of the behavior of clays is conducted by numerical simulation tests of compression and swelling by using the oedometer. This analysis is conducted using the software CASTEM2000 team from CEA-France. This simulation allows-among others-to develop a predictive procedure for estimating the parameters of swelling by the use of constitutive equations of Cam-Clay and Alonso. It should be noted that different simulations are performed; those using oedometer tests by the Cam- Clay model, and Alonso and free swell tests by the Alonso model. The results of this work show that the compressibility has been correctly simulated by both models. The phase of swelling has been simulated by the model of Alonso as the Cam-Clay model can simulate it. It should be noted that the Alonso model underestimates very fluffy swelling soils

Study of a Pendulum in Vivo Electromechanical Generator to be Used in a Knee Prosthesis

International audienceThis paper presents the principle and the energy potential of an original electromechanical generator that uses human body natural motions during walking, in order to create an autonomous generator. This in vivo and noninvasive system is intended to be used in intelligent knee prosthesis. As the combined human, mechanical, and electrical phenomena are very significant, a mechanical and an electrical study are then carried to evaluate the recoverable power

Using Artificial Neural Networks Approach to Estimate Compressive Strength for Rubberized Concrete

Artificial neural network (ANN) is a soft computing technique that has been used to predict with accuracy compressive strength known for its high variability of values. ANN is used to develop a model that can predict compressive strength of rubberized concrete where natural aggregate such as fine and coarse aggregate are replaced by crumb rubber and tire chips. The main idea in this study is to build a model using ANN with three parameters that are: water/cement ratio, Superplasticizer, granular squeleton. Furthermore, the data used in the model has been taken from various literatures and are arranged in a format of three input parameters: water/cement ratio, superplasticizer, granular squeleton that gathers fine aggregates, coarse aggregates, crumb rubber, tire chips and output parameter which is compressive strength. The performance of the model has been judged by using correlation coefficient, mean square error, mean absolute error and adopted as the comparative measures against the experimental results obtained from literature. The results indicate that artificial neural network has the ability to predict compressive strength of rubberized concrete with an acceptable degree of accuracy using new parameters

Swelling and Geotechnical Cartography of Saida Soils

The urban expansion and the increase in population led the urbanization to use the spaces called “at risk”.The integration and the treatment of ground’s movements constitute an important characteristic of the equilibrium established by nature. In the Saïda town (Algeria), many projects built on grounds with problems showed signs of degradations such as cracks in structures. These degradations led to the total destruction of the buildings. The principal causes of these disasters are: the expansive nature of soils and landslides, and the disaster phenomenon not considered in the first study of these constructions. The damage also touched road embankments, highways and foundations. In order to solve these problems, it was necessary to propose a geotechnical and risk map for the ZHUN EAST (ESSALAM city, Saïda), a city which includes several yards of the soil with problems, using the Geographical Information Systems (GIS/MapInfo). These tools enable us to express the perception of space and data processing, and consequently the cartography is carried out in an optimal way. These geotechnical and risk maps have a great part of importance in all levels of a study as information, working paper, alert, and especially is a tool for the decision-making aid, by expressing tendencies and orientations. They enabled us to give a field representing the active and potential movements with a hierarchy of risks to guide the developer and the engineer

A High-Order Sliding Mode Observer for Sensorless Control ofDFIG-Based Wind Turbines

International audienceThis paper deals with the sensorless control of a doubly-fed induction generator (DFIG) based wind turbine. The sensorless control scheme is based on a high-order sliding mode (HOSM) observer to estimate the DFIG rotational speed. Indeed, high-order sliding mode observers provide theoretically finite time exact state observation and estimation of absolutely continuous unknown inputs. The proposed global control strategy combines an MPPT using a high-order sliding mode speed observer and a high-order sliding mode for the DFIG control. This strategy presents attractive features such as chattering-free behavior, finite reaching time, robustness and unmodeled dynamics (generator and turbine). Simulations using the wind turbine simulator FAST on a 1.5- MW three-blade wind turbine are carried out for the validation of the proposed sensorless control strategy

A DC-DC Converter-Based PEM Fuel Cell System Emulator

International audienceThe Proton Exchange Membrane Fuel Cell (PEMFC) is being investigated as an alternate power source for various applications as transportation and emergency power supplies. Fuel cell systems are characterized by high costs and complex auxiliary devices. For this reason, a fuel cell emulator can be used as a suitable and economic alternative to a real one for developing and testing a fuel cell power conditioning system. The fuel cell emulator must be able to reproduce the FC nonlinear output voltage-current characteristic. This paper proposes then a possible solution to emulate a PEMFC system by using a DC-DC converter. The fuel cell system, including all its auxiliaries and related control systems, is emulated by a full-bridge converter experimentally achieved and controlled in the DSP2812 environment. The converter-based system allows the behavior of any fuel cell to be easily emulated and can be used in laboratory as a low-cost system for design and experimental purposes since only a DC-DC control modification is necessary

Development of Wind Turbines Prototyping Software Under Matlab/Simulink® Through Undergraduate Student Projects

International audienceElectrical Engineering and more particularly Power Engineering at the undergraduate level is facing a crisis at many French universities in terms of enrollment. One reason is the attraction of “newer” areas like computer engineering, which seem to excite the students more and pay higher starting salaries. In this difficult context, a significant educational investment is necessary to excite the students and entice them into Power Engineering. An area that students universally find interesting is alternate energy systems based on a renewable energy supply like wind. What is interesting with this area is that it includes the fundamental material that already exists in many energy conversion courses. Therefore, in this paper the authors present the development of a wind turbine prototyping software under Matlab/Simulink® through undergraduate student projects within the Electrical and Computer Engineering Professional Institute (IUP GEII) at Amiens, France [1]. This software was developed by a group of three students of the Institute third and final year. It was then used by another group of three students of the Institute second year to realize a wind energy system model

Research on Fault Analysis and Fault-Tolerant Control of EV/HEV Powertrain

International audienceThis paper presents research works in the topics of fault analysis and fault tolerant control of an electric vehicle powered by an inverter-fed induction motor drive and the usual sensors. The considered failures are mainly measurement error due to faulty sensors and power inverter malfunctions. When sensor failure occurs, both software and hardware redundancies have been investigated. Software redundancy has been evaluated in case of speed sensor failure. Hardware redundancy has been used in the case of power inverter failures with a fault-tolerant 4-leg topology. This topology exploits the induction motor neutral accessibility for fault-tolerant purposes. The proposed fault-tolerant approach brings a significant improvement compared to the phase-leg topology. This paper also presents the experimental validation of an efficient reconfiguration mechanism (transition strategy) at sensor fault occurrence

A 7-Level Single DC Source Cascaded H-Bridge Multilevel Inverter with a Modified DTC Scheme for Induction Motor-Based Electric Vehicle Propulsion

International audienceThis paper presents a new hybrid cascaded H-bridge multilevel inverter motor drive DTC scheme for electric vehicles where each phase of the inverter can be implemented using a single DC source. Traditionally, each phase of the inverter requires n DC source for (2n + 1) output voltage levels. In this paper, a scheme is proposed that allows the use of a single DC source as the first DC source which would be available from batteries or fuel cells, with the remaining (n − 1) DC sources being capacitors. This scheme can simultaneously maintain the capacitors of DC voltage level and produce a nearly sinusoidal output voltage due to its high number of output levels. In this context, high performances and efficient torque and flux control are obtained, enabling a DTC solution for hybrid multilevel inverter powered induction motor drives intended for electric vehicle propulsion. Simulations and experiments show that the proposed multilevel inverter and control scheme are effective and very attractive for embedded systems such as automotive applications

PWM Inverter-Fed Induction Motor-Based Electrical Vehicles Fault-Tolerant Control

International audienceThis paper proposes a fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. In a vehicle context, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed. Two topologies exploit the induction motor neutral accessibility for fault-tolerant purposes. The 4-wire topology uses then classical hysteresis controllers to account for the IGBT failures. The 4-leg topology, meanwhile, uses a specific 3D space vector PWM to handle vehicle requirements in terms of size (DC bus capacitors) and cost (IGBTs number). Experiments on an induction motor drive and simulations on an electric vehicle are carried-out using a European urban driving cycle to assess the FTC scheme performance and effectiveness