Publications

Purpose: To determine the anti-inflammatory and anti-ulcer properties of the aerial parts of Centaurea tougourensis Boiss. & Reut.

 

Methods: The effects of n-butanol (n-BuOH) extract of the aerial part of Centaurea tougourensis on carrageenan-induced paw edema and ethanol-induced gastric mucosal damage were determined at 2 doses (200 and 400 mg/kg, po) in a mouse model. For each test, the animals were randomly divided into negative and positive control groups, as well as extract-treated groups. The mice were observed for any sign of inflammation for a period of 24h.

 

Results: Reduction of paw edema by C. tougourensis extract was highly significant (p < 0.001) at a dose of 400 mg/kg 24 h after carrageenan injection, with 55.26 % inhibition, followed very closely by 53.15 % inhibition at the dose of 200 mg/kg; indomethacin group showed an inhibition of 60 %. Histological examination supported the inhibition results. A significant reduction in inflammation by the extract at a dose of 400 mg/kg was also observed. No sign of ulcer was observed with C. tougourensis at the two doses (200 and 400 mg/kg). The total polyphenol content of the n-BuOH extract was 85.44 цg gallic acid equivalent/mg of extract. Tannins were the most abundant fraction (51.87 цg tannic acid equivalent/mg of extract), followed by flavonoids (25.55 цg quercetin equivalent/mg of extract).

 

Conclusion: The results indicate that C. tougourensis may have potential beneficial effects in the treatment of diseases associated with inflammation and pain, besides its protective effect on the gastrointestinal tract.

In this article, we consider a coupled system of two nonlinear hyperbolic equations, where the exponents in the damping and source terms are variables. First, we prove a theorem of existence and uniqueness of weak solution, by using the Faedo Galerkin approximations and the Banach fixed point theorem. Then, using the energy method, we show that certain solutions with positive initial energy blow up in finite time. We also give some numerical applications to illustrate our theoretical results.

This paper provides a new proof of the existence and uniqueness of the solution for a nonlinear boundary value problem

which describes the study of two-phase Stefan problems on the semi-infinite line [0, ∞). This result considerably extends the analysis of a recent work. A highly accurate analytic approximate solution of this problem is also provided via the Adomian decomposition method.

To evaluate the performance of concrete load bearing walls in a structure under horizontal loads after being exposed to real fire, two steps were followed. In the first step, an experimental study was performed on the thermo-mechanical properties of concrete after heating to temperatures of 200-1000oC with the purpose of determining the residual mechanical properties after cooling. The temperature was increased in line with natural fire curve in an electric furnace. The peak temperature was maintained for a period of 1.5 hour and then allowed to cool gradually in air at room temperature. All specimens were made from calcareous aggregate to be used for determining the residual properties: compressive strength, static and dynamic elasticity modulus by means of UPV test, including the mass loss. The concrete residual compressive strength and elastic modulus values were compared with those calculated from Eurocode and other analytical models from other studies, and were found to be satisfactory. In the second step, experimental analysis results were then implemented into structural numerical analysis to predict the post-fire load-bearing capacity response of the walls under vertical and horizontal loads. The parameters considered in this analysis were the effective height, the thickness of the wall, various support conditions and the residual strength of concrete. The results indicate that fire damage does not significantly affect the lateral capacity and stiffness of reinforced walls for temperature fires up to 400oC.

In the present study, both experimental and numerical were conducted on a free surface flow over an obstacle. Numerical simulations were performed using the Renormalization Group (RNG-k-ɛ) based Reynolds-Averaged Navier–Stokes (RANS) turbulence model coupled with the Volume OF Fluid (VOF) method in FLUENT Software to investigate the effect of the channel slope on the flow pattern upstream, above and downstream the obstacle. Respectively, 5%, 7%, 8%, 10%, 20% and 50% channel slopes were considered. Numerical simulation has showed a good agreement compared against experimental results. Effect of the slope on the flow is observed particularly upstream of the obstacle where the flow takes the vertical direction after hitting the upstream wall. The more the slope becomes steeper, the higher the level of the water is. Recirculation zones in the case of a horizontal channel are elongated downstream the weir, whereas in the case of a sloped channel, they are localized just at the foot of the downstream wall.

The present study focuses on the investigation of the behaviour of a reduced model of a reinforced soil massif by a sand column tested in the laboratory. These tests involved the installation of sand columns in clay specimens (kaolin) by different methods. The specimens thus obtained are subjected to the same oedometric loading program. The first part of this work aims to study the effect of the intensity of the compaction stress of the sand columns on the surrounding soil and the effect on the behaviour of the soil-column massif. The sand columns were installed with the soil replacement method and with compacting of the columns (WR_WC). Three different compaction stresses were used to install the columns. In the second part, a sand column 20 mm in diameter was installed by two methods: one with replacement of the soil (WR) and without compaction and the other with displacement of the soil (WD). A comparison between the two methods has been established. By determining the equivalent characteristics for the soil-column massif, this study made it possible to characterize the effect of the installation method of the columns on the settlements, the void ratioe of kaolin, the equivalent void ratio e_eq of the massif soil-column and on the compressibility parameters of the massif (equivalent compression index C_ceq and swelling index C_seq), by comparing the results obtained with those of the unreinforced soils that constitute the reference case. The results obtained showed that the techniques used for the installation of columns have significant effects on the behaviour of reinforced massifs.

The Safety Instrumented System (SIS) is an automated system used to implement one or more safety instrumented functions. A SIS, like the Emergency Shutdown (ESD) system, consists of any combination of sensor(s), safety PLC(s) and final element(s) (e.g. ESD valves). ESD valves are the last line of defense against risks, although the ESD valve has high performance, the data (based on expert judgment and OREDA database) indicates that ESD valves failures are the most critical in the ESD systems. In order to improve the reliability and safety of these valves, we applied the FMEDA diagnostic technique. We started with a decomposition of the ESD valve to the subsystems and we identified their functions. Then we described the failure modes, their mechanisms, their sites and their effects. Then we identified the impact of each failure mode according to the criticality classes and identified the failure rates and their class according to the criticality and the detectability by automatic diagnosis of each mode and from the failure rates we calculated the Safe Failure Fraction (SFF) and Safety Integrity Level (SIL) required and we concluded that the actuator subsystem is the most critical system. Finally, we proposed preventive and protective measures to eliminate or reduce the risk of failure.

In this paper, the exact solutions to the AB nonlinear system are investigated. This system is reduced via two different transformations to a sine-Gordon equation and a quasilinear equation for a new dependent variable ϕ. Solutions to a sineGordon equation and a quasilinear equation are found. Hence, the original system can well be solved for such ϕ. Also, a similar approach is proposed to solve analytically an eventual extension system for the case of variable coefficients.

In recent years the development of health science to improve people’s lives and reduce the death rate from cardiovascular disease, researchers have invested in the solution of stents to treat cardiovascular disease. Usually a permanent implant (metal stent) is used to treat a temporary disease, effective on elastic recoil and negative remodeling, but promoting intimate proliferation. This is combated by an active stent, which nevertheless induces chronic inflammation and delayed healing (because of active drugs), with the risk of late thrombosis. The idea of resolution leads to the study of the behavior of temporary stent biodegradable and bioresorbable, once the healing process is completed. The purpose of this study is to reduce the disadvantages of metal stents, to do this; a biodegradable material (polylactic acid) is used. The fatigue behavior of a stent after its placement using geometric parameters selected from clinical cases (diastole and systole). A finite element numerical study in the field of biomaterial fatigue is proposed in order to investigate and understand the biodegradable behavior of the stent. The results of the numerical study show the predicted lifetime of the biodegradable fragrance.

In recent years the development of health science to improve people’s lives and reduce the death rate from cardiovascular disease, researchers have invested in the solution of stents to treat cardiovascular disease. Usually a permanent implant (metal stent) is used to treat a temporary disease, effective on elastic recoil and negative remodeling, but promoting intimate proliferation. This is combated by an active stent, which nevertheless induces chronic inflammation and delayed healing (because of active drugs), with the risk of late thrombosis. The idea of resolution leads to the study of the behavior of temporary stent biodegradable and bioresorbable, once the healing process is completed. The purpose of this study is to reduce the disadvantages of metal stents, to do this; a biodegradable material (polylactic acid) is used. The fatigue behavior of a stent after its placement using geometric parameters selected from clinical cases (diastole and systole). A finite element numerical study in the field of biomaterial fatigue is proposed in order to investigate and understand the biodegradable behavior of the stent. The results of the numerical study show the predicted lifetime of the biodegradable fragrance.

Purpose – The increasing complexity of industrial systems is at the heart of the development of many fault diagnosis methods. The artificial neural networks (ANNs), which are part of these methods, are widely used in fault diagnosis due to their flexibility and diversification which makes them one of the most appropriate fault diagnosis methods. The purpose of this paper is to detect and locate in real time any parameter deviations that can affect the operation of the blowout preventer (BOP) system using ANNs.
Design/methodology/approach – The starting data are extracted from the tables of the HAZOP (HAZard and OPerability) method where the deviations of the parameters of normal BOP operating (pressure, flow, level and temperature) are associated with an initial rule base for establishing cause and effect of relationships between the causes of deviations and their consequences; these data are used as a database for the neural network. Three ANNs were used, the multi-layer perceptron network (MLPN), radial basis functions network (RBFN) and generalized regression neural networks (GRNN). These models were trained and tested, then, their comparative performances were presented. The respective performances of these models are highlighted following their application to the BOP system.
Findings – The performances of the models are evaluated using determination coefficient (R2), root mean square error (RMSE) and mean absolute error (MAE) statistics and time execution. The results of this study show that the RMSE,MAE and R2 values of the GRNN model are better than those corresponding to the RBFN and MLPN models. The GRNN model can be applied with better performance, to establish a diagnostic model that can detect and to identify the different causes of deviations in the parameters of the BOP system.
Originality/value – The performance of the trained network is found to be satisfactory for the real-time fault diagnosis. Therefore, future studies on modeling the BOP system with soft computing techniques can be concentrated on the ANNs. Consequently, with the use of these techniques, the performance of the BOP system can be ensured performing only a limited number of monitoring operations, thus saving engineering effort, time and funds.

Purpose The increasing complexity of industrial systems is at the heart of the development of many fault diagnosis methods. The artificial neural networks (ANNs), which are part of these methods, are widely used in fault diagnosis due to their flexibility and diversification which makes them one of the most appropriate fault diagnosis methods. The purpose of this paper is to detect and locate in real time any parameter deviations that can affect the operation of the blowout preventer (BOP) system using ANNs. Design/methodology/approach The starting data are extracted from the tables of the HAZOP (HAZard and OPerability) method where the deviations of the parameters of normal BOP operating (pressure, flow, level and temperature) are associated with an initial rule base for establishing cause and effect of relationships between the causes of deviations and their consequences; these data are used as a database for the neural network. Three ANNs were used, the multi-layer perceptron network (MLPN), radial basis functions network (RBFN) and generalized regression neural networks (GRNN). These models were trained and tested, then, their comparative performances were presented. The respective performances of these models are highlighted following their application to the BOP system. Findings The performances of the models are evaluated using determination coefficient (R2), root mean square error (RMSE) and mean absolute error (MAE) statistics and time execution. The results of this study show that the RMSE, MAE and R2 values of the GRNN model are better than those corresponding to the RBFN and MLPN models. The GRNN model can be applied with better performance, to establish a diagnostic model that can detect and to identify the different causes of deviations in the parameters of the BOP system. Originality/value The performance of the trained network is found to be satisfactory for the real-time fault diagnosis. Therefore, future studies on modeling the BOP system with soft computing techniques can be concentrated on the ANNs. Consequently, with the use of these techniques, the performance of the BOP system can be ensured performing only a limited number of monitoring operations, thus saving engineering effort, time and funds.

Renewable energies offer new solutions to an ever-increasing energy demand. Wind energy is one of the main sources of electricity production, which uses winds to be converted to electrical energy with lower cost and environment saving. The major failures of a wind turbine occur in the bearings of high-speed shafts. This paper proposes the use of optimized machine learning to predict the Remaining Useful Life (RUL) of bearing based on vibration data and features extraction. Significant features are extracted from filtered band-pass of the squared raw signal where the health indicators are automatically selected using relief technique. Optimized Adaptive Neuro Fuzzy Inference System (ANFIS) by Partical Swarm Optimization (PSO) is used to model the non linear degradation of the extracted indicators. The proposed approach is applied on experimental setup of wind turbine where the results show its effectiveness for RUL estimation.

The integration of a fault tolerance mechanism in critical real-time embedded systems is an important and required property to ensure the continuity of delivering the expected service even in the presence of faults to avoid catastrophic consequences that can be generated in the event of failure of these systems. In this research paper we present a solution to tolerate permanent faults of one processor in heterogeneous distributed real-time embedded systems by using software redundancy solutions based on active and passive replication of dependent tasks in the point-to-point connection. The methodology proposed consists to generate a distribution/scheduling of tasks on hardware architecture and also to tolerate permanent faults of a single processor by executing simultaneously two replicas of a task, the first which ends its execution blocks the second is running. this principle saves very considerable time in distribution/scheduling length with and without errors.