This work presents an experimental study of the hydromechanical behavior of a natural swelling soil taken from Boumagueur region east of Algeria. Several pathological cases due to the soil shrinkage / swelling phenomenon were detected in this area. In a first part, the hydric behavior on drying-wetting paths was made, using the osmotic technics and saturated salts solutions to control suction. In The second part, using a new osmotic oedometer, the coupled behavior as a function of applied stresses and suction was investigated. It was shown that soil compressibility parameters was influenced by suction variations that an increase in suction is followed by a decrease in the virgin compression slope. On the other hand, the unloading slope of the oedometric curves was not obviously affected by the imposed suction. The decrease in suction strongly influences the apparent preconsolidation pressure, ie during swelling of the samples after wetting.

In urban areas, the control of ground surface settlement is an important issue during shield tunnel-boring machine (TBM) tunneling. These ground movements are affected by many machine control parameters. In this article, a finite difference (FD) model is developed using Itasca FLAC-3D to numerically simulate the whole process of shield TBM tunneling. The model simulates important components of the mechanized excavation process including slurry pressure on the excavation face, shield conicity, installation of segmental lining, grout injection in the annular void, and grout consolidation. The analysis results from the proposed method are compared and discussed in terms of ground movements (both vertical and horizontal) with field measurements data. The results reveal that the proposed 3D simulation is sufficient and can reasonably reproduce all the operations achieved by the TBM. In fact, the results show that the TBM parameters can be controlled to have acceptable levels of surface settlement. In particular, it seems that moderate face pressure can reduce ground movement significantly and, most importantly, can prevent the occurrence of face-expected instability when the shield crosses very weak soil layers. The shield conicity has also an important effect on ground surface settlement, which can be partly compensated by the grout pressure during tail grouting. Finally, the injection pressure at the rear of the shield significantly reduces the vertical displacements at the crown of the tunnel and, therefore, reduces the settlement at the ground surface.

In this article, we present a comparative study between two control techniques applied on the Permanent Magnet Synchronous Machine (PMSM), namely vector control and fuzzy logic. This comparison is based on three criteria: qualitative, quantitative and robust during the transient and permanent operation of the system. The latter comprises a machine is driven through the stator variables by two bidirectional converters. In the first part, we have presented the individual modeling of the global chain (PMSM, Inverter, and Rectifier). Then we presented and developed the two commands techniques to control the speed and the torque produced by this machine. The results of this study made it possible to evaluate the performance of these controls.

This paper presents a comparative study between two strategies for the direct torque control (DTC) of the permanent magnet synchronous generator (PMSG) based on wind energy conversion system (WECS). The first method is a conventional direct torque control DTC and it is based on hysteresis controllers where the torque and the flux are regulated by these controllers. The second one is direct torque control by space vector modulation strategy (DTC-SVM) where the torque and flux are regulated by PI controllers. The simulation results are implemented by using MATLAB/SIMULINK. The main feature of the proposed (DTC-SVM) strategy is the reduction of torque and flux ripples. The proposed approach can be considered as an alternative solution to the control of PMSG.

This paper presents a comparative study between two strategies for the direct torque control (DTC) of the permanent magnet synchronous generator (PMSG) based on wind energy conversion system (WECS). The first method is a conventional direct torque control DTC and it is based on hysteresis controllers where the torque and the flux are regulated by these controllers. The second one is direct torque control by space vector modulation strategy (DTC-SVM) where the torque and flux are regulated by PI controllers. The simulation results are implemented by using MATLAB/SIMULINK. The main feature of the proposed (DTC-SVM) strategy is the reduction of torque and flux ripples. The proposed approach can be considered as an alternative solution to the control of PMSG.

This investigation examines mathematical modelling and experimental validation of two types of solar cookers: a box type with tilted intercept area equipped with one external reflector, and a parabolic cooker with a new configuration. Experiments were carried out with the cookers filled with two kilograms of water from 08:00 to 15:00 solar time. During the experiments, temperature gain in the box-type solar cooker was recorded at about 69.8 °C and in the parabolic-type solar cooker at 73.6 °C at the stagnation point. Direct normal irradiation in three distinct study areas was observed and found that it varied from 7.6 to 10 kWh m⁻². Cooking pot placed in parabolic cooker was varied between 130 and 132 °C. Centre and south-east regions of study areas where global irradiation varied from 8 to 8.4 kWh m⁻² were found suitable for box-type solar cooker and cooking pot temperature were found in the range of 100 °C to 105 °C. Mathematical modelling was programmed in MATLAB. The theoretical results were consistent with experiential data for both types of solar cookers. The effectiveness of the two cooker types can be deduced from the maps. It is found the use of the cookers in Northern and Southern regions of the country was not identical. Their suitability for cooking depends on the amount of solar radiations received.

The magnetohydrodynamics (MHD) is an important interdisciplinary field. It is the interaction between an electromagnetic field and an electrically conducting fluid. Electromagnetic pumps are widely used for the transportation of the fluids in a variety of technological processes. The advantage of these devices is that permits the pumping of liquids without moving parts. The design of the pump is considered as an optimization problem where the objective function is the minimum of the MHD pump mass with both geometrical and electromagnetic contraints type. The obtained optimization results using the finite volume method with Matlab software show the performances of the used stochastic simulated annealing method.

This paper designs an indirect power control method for brushless doubly fed induction generator (BDFIG), in which the stator is attached to grid with back-to-back space vector modulation (SVM) converter that converts the generated wind power. Our control method is a sliding mode control based on the theory of variable structure control. Specifically, the active and reactive powers, which are exchanged between the stator of the BDFIG and the grid in a linear and decoupled manner, are subjected to decoupled, vector control. In addition, a proportional integral (PI) controller was implemented to keep the DC-voltage constant for the back-to-back SVM converter. The efficiency of our control strategy was validated through simulation. The research greatly promotes the control of renewable energy generators.

This paper deals with the robust power control of a grid-connected brushless doubly-fed induction generator (BDFIG) driven by the variable speed wind turbine. With the using of a super twisting algorithm which is a high-order sliding mode controller (HOSMC). This approach guarantees both the dynamic performance and the same robustness as traditional first order (SMC) algorithm and reduces the chattering phenomenon, which is the biggest disadvantage in the implementation of this technique. The developed algorithm relies on the decoupling control by implementing the strategy of oriented grid flux vector control. In order to enhance the desired performances, an attempt is made by controlling the generated stator active and reactive powers in a linear and decoupled manner to ensure the global asymptotical stability, HOSMC approach is implemented. Therefore, an optimal operation of the BDFIG in sub-synchronous operation is used in addition to the stator power flows where the stator power factor is kept in a unity. The suggested method is examined with the Matlab/Simulink software. The performances and the feasibility of the designed control are illustrated by simulation results.

Purpose The purpose of this paper is to validate a fuzzy risk graph model through a case study results carried out on a safety instrumented system (SIS). Design/methodology/approach The proposed model is based on an inference fuzzy system and deals with uncertainty data used as inputs of the conventional risk graph method. The coherence and redundancy of the developed fuzzy rules base are first verified in the case study. A new fuzzy model is suggested for a multi-criteria characterization of the avoidance possibility parameter. The fuzzy safety integrity level (SIL) is determined for two potential accident scenarios. Findings The applicability of the proposed fuzzy model on SIS shows the importance and pertinence of the proposed fuzzy model as decision-making tools in preventing industrial hazards while taking into consideration uncertain aspects of the data used on the conventional risk graph method. The obtained results show that the use of continuous fuzzy scales solves the problem of interpreting results and provides a more flexible structure to combine risk graph parameters. Therefore, a decision is taken on the basis of precise integrity level values and protective actions in the real world are suggested. Originality/value Fuzzy logic-based safety integrity assessment allows assessment of the SIL in a more realistic way by using the notion of the linguistic variable for representing information that is qualitative and imprecise and, therefore, ensures better decision making on risk prevention.

Purpose The purpose of this paper is to deal with the allocation requirements of the dependability of the multiphase systems. Design/methodology/approach It consists of a proposal for a combined methodology based on the simultaneous use of decomposition systems and reliability allocation method. Findings In the developed methodology, the authors use the principles of risk assessment and propose a new formulation of weight allowance with reference to the structural-functional dependence. Practical implications The suggested methodology provides invaluable help to implementation process analysis. Originality/value The adopted allocation approach is based on the use of a three-dimensional model: temporal, structural and functional decomposition of systems.

Purpose The risk control is an unavoidable step in the risk management process. It is materialized by concrete actions of risks reduction in order to decrease their likelihood and/or their severity and also to preserve the environment. The paper aims to discuss this issue. Design/methodology/approach The main goal of the proposed methodology is to define the safety barriers (SB) that can be realized and their contribution to reduce major accidents scenarios that may occur in high-risk establishments. Findings In the proposed methodology, the authors present a combination of methods to prove the effectiveness of SB in an industrial installation. Practical implications The proposed methodology is a valuable help to industrialists to secure their industrial activities and preserve the environment at the same time. Originality/value The retained methods are often used separately for audit purposes or risk assessments of high-risk industrial facilities. In this paper, three methods have been selected and articulated in an approach for a better evaluation of risk control level.

Risk mapping is the foundation of the risk prevention strategy. It allows for the understanding of all factors that may affect the activities. It is a collective decision based on negotiation between the actors. Argument-based negotiation accelerates the negotiation process and converges it toward a final and common decision. It is in this context that this paper aims to illustrate the contribution of the improved PCA and AHP tools, considered as arguments, to the classification of major accident risks.

Purpose The purpose of this paper is to propose a new managerial method to integrate the environmental dimension in the domino effects (DEs) analysis. Design/methodology/approach The proposed method is a three-step approach: identification of primary hazards in the form of potential events causing the DE, a mixed quantification (deterministic and probabilistic) of the risk of the DEs with a view to its control and capitalizing the results from the BLEVESOFT software as well as those relating to the probability of occurrence of the DEs in the form of a prioritized action plan dedicated to surrounding environments (proximity territory). Findings The primary hazards are technologically manageable at the studied system but are unpredictable if triggered at the environmental subsystem because they are difficult to be managed and often cause panic, which is a form of a very catastrophic DE. Research limitations/implications The research could affect members of the engineering and construction industry, and can be applied in several domains since it studies the DE phenomenon. which is a common problem especially in industrials plants. Practical implications The proposal method is applied in an industrial terminal in Algeria. Originality/value This paper presents an exploratory study of using a new managerial method that aims to combine the potentialities of geomatic sciences that allow the spatial representation of nearby territories to assess the severity of DEs through a deterministic approach, and the modeling of DEs as well as their analysis by a probabilistic approach.

Using a risk matrix for Risk mapping constitutes the basis of risk management strategy. It aims to classify the identified risks with regards to their management and control. This risk classification, which is based on the frequency and the severity dimensions, is often carried out according to a procedure founded on experts’ judgments. In order to overcome the subjectivity bias of this classification, this paper presents the contribution of the Principal Components Analysis (PCA) method: an exploratory method for graphing risks based on factors that allow a better visualized classification of scenarios accidents. Still, the commonly encountered problem in the data classified by the PCA method resides in the main factors of classification; we judged useful to frame these letters by an algebraic formulation to make an improvement of this classification possible. The obtained results show that the suggested method is a promising alternative to solve the recurring problems of risk matrices, notably in accident scenarios’ classification.

Purpose For many years, the concept of safety culture has attracted researchers from all over the world, and more particularly in the area of healthcare services. The purpose of this paper is to measure safety culture dimensions in order to improve and promote healthcare in Algeria. Design/methodology/approach The used approach consists of getting a better understanding of healthcare safety culture (HSC) by measuring the perception of healthcare professionals in order to guide promotion actions. For this, the Hospital Survey on Patient Safety Culture questionnaire was used in a pilot hospital setting where it was distributed on a number of 114 health professionals chosen by stratified random sampling. Findings The results showed that the identified priority areas for HSC improvement help in establishing a trust culture and a non-punitive environment based on the system and not on the individual. Originality/value Safety is recognized as a key aspect of service quality, thus measuring the HSC can help establish an improvement plan. In Algerian health facilities, this study is considered the first to examine perceptions in this particular area. The current results provide a baseline of strengths and opportunities for healthcare safety improvement, allowing the managers of this type of facilities to take steps that are more effective.

In this paper, an iterative technique, employing the T formulation associated with the finite element method, based on Maxwell’s equations and the Biot-savart law, is used for analyzing the density of eddy currents in composite carbon fiber reinforced polymer (CFRP) materials. For this purpose, a code has been developed for solving an electromagnetic 3D non-destructive evaluation problem. This latter permits the characterization of this CFRP and determinate of fibers orientation using the impedance variation which is implanted in polar diagram. Firstly, the obtained results are compared with those of the analytical model. This comparison reveals a high concordance which proves the validity of the proposed method. Secondly, three different applications are shown for illustrating the characterization of unidirectional, bidirectional and multidirectional piece using a rectangular coil plotted in normalized impedance diagram.

This paper presents a fuzzy logic controller destined to the doubly-fed induction motor (DFIM) speed controlling. It solves the problems associated with the conventional IP (Integral Proportional) controller. This fuzzy logic controller is based on the decoupling control to enhance robustness under different operating conditions such as load torque and in the presence of parameters variation. The simulation results for various scenarios show the high performances of the proposed control in terms of piloting effectiveness, precision, rapidity and stability for the high powers DFIM operating at variable speeds.

This article presents a study of a Multi-coils circular eddy current non-destructive testing sensor for determining the fibers orientation as well as the detection of defect in multidirectional carbon fibers reinforced polymer (CFRP). The developed sensor contains 16 rectangular coils connected in series and supplied by a single-phase sinusoidal source. This sensor allows the annulations of the mechanical rotation of the conventional sensors and it permits to reduce the inspection procedure duration. The electromagnetic phenomena are calculated by using 3D finite element method (FEM) based on the electromagnetic AV-A formulation. Finally, the Multi-coils circular sensor responses are analyzed through polar diagrams of the impedance variation, where the defect is taken into consideration. A great concordance between the obtained results and those of literatures has been noticed. The provided results show that the proposed sensor allows an efficient characterization of multidirectional CFRP and detection of defects in different layers.