Dynamic Soil Structure Interaction Study

The effect of the surrounding soil, as depicted by the soil-structure interaction effect, on the dynamic behavior of Brezina concrete gravity arch dam, located in El-Beyadh at the west of Algeria, is investigated in the present study. Both modal and transient analyses are performed for the dam, presented and discussed as a case study for this work. A three-dimensional finite element model (SOLID185) using ANSYS software is created to model the dam body and the adjacent soil. Three different seismic records having identical peak ground acceleration of 0.2g, assuming three different viscous damping ratios: 2%, 5% and 10%, are used in the analysis. The results of this analysis constitute a data base for a parametric study investigating the soil-structure interaction effect, that of the mass of soil foundation and that of the damping ratio on the dynamic behavior of Brezina concrete arch dam. Dynamic analyses for Brezina concrete arch dam for the three studied cases: dam without soil, dam with mass soil foundation and dam with massless soil foundation show that the presence of the soil in the model develops more stresses in the dam body, especially when the soil mass is considered in the model

Phytochemical screening and antioxidant activity of four Moroccan aromatic plant methanolic extracts and essential oils

This work aimed to evaluate and to compare the antioxidant potential between essential oils (EOs) and methanolic extracts (MEs) of Anthemis tenuisecta, Cladanthus arabicus Cass., Ismelia carinata Schousb., and Thymus broussonetii Boiss subsp. broussonetii collected from Morocco. The EOs used in this study were isolated by hydrodistillation using a Clevenger-type apparatus. The MEs were obtained by methanol maceration. The main compounds of EOs were identified using gas chromatography-mass spectrometry. The MEs of the four plant species were tested for total phenolics and total flavonoids. The in vitro antioxidant activity of EOs and MEs was carried out using diphenyl-1-picrylhydrazyl (DPPH) assay. The antioxidant activity of MEs showed high correlations with phenolic compounds. For both fractions, the best IC50 values were given by T. broussonetii. The MEs revealed significantly (p ≤ 0.05) better antioxidant activity than EOs. The results suggest that A. tenuisecta, C. arabicus, I. carinata, and T. broussonetii may be potential sources of natural antioxidants

Chemical composition, vasorelaxant, antioxidant and antiplatelet effects of essential oil of Artemisia campestris L. from Oriental Morocco

Background: Artemisia campestris L. (Asteraceae) is a medicinal herb traditionally used to treat hypertension and many other diseases. Hence, this study is aimed to analyze the essential oil of A. campestris L (AcEO) and to investigate the antiplatelet, antioxidant effects and the mechanisms of its vasorelaxant effect. Methods: The chemical composition of AcEO was elucidated using GC/MS analysis. Then, the antioxidant effect was tested on DPPH radical scavenging and on the prevention of β-carotene bleaching. The antiplatelet effect was performed on the presence of the platelet agonists: thrombin and ADP. The mechanism of action of the vasorelaxant effect was studied by using the cellular blockers specified to explore the involvement of NO/GC pathway and in the presence of calcium channels blockers and potassium channels blockers. Results: AcEO is predominated by the volatiles: spathulenol, ß-eudesmol and p-cymene. The maximal antioxidant effect was obtained with the dose 2 mg/ml of AcEO. The dose 1 mg/ml of AcEO showed a maximum antiplatelet effect of, respectively 49.73% ±9.54 and 48.20% ±8.49 on thrombin and ADP. The vasorelaxation seems not to be mediated via NOS/GC pathway neither via the potassium channels. However, pretreatment with calcium channels blockers attenuated this effect, suggesting that the vasorelaxation is mediated via inhibition of L-type Ca2+ channels and the activation of SERCA pumps of reticulum plasma. Conclusion: This study confirms the antioxidant, antiplatelet and vasorelaxant effects of A.campestris L essential oil. However, the antihypertensive use of this oil should be further confirmed by the chemical fractionation and subsequent bio-guided assays

Towards a thermo-mechanical characterization approach of buildings' envelope

This paper investigates the numerical and experimental thermo-mechanical characterization of buildings' structure for energy efficiency. A finite element model (FEM) of a small-scaled building is carried out using mesh refining tools at thermal bridges zones. The latter is revealed towards infra-red (IR) camera measurements. Galvanized steel is the main material composing the building's walls in which heat transfer coefficients are determined based on measurements of external and internal averaged temperatures. Hence, the physical model includes thermal conductivity, heat convective and radiative phenomena. Results of computations, made with finite elements method, using the cast3m tool, show a good agreement compared to those obtained from experiments

Impact of material nonlinearity of dam-foundation rock system on seismic performance of concrete gravity dams

This paper shows the impact of material nonlinearity of a dam-foundation rock system on seismic performance of Oued Fodda concrete gravity dam, located at northwestern side of Algeria. For the purpose, a three-dimensional dam-foundation rock system finite element model is employed in analyses. The hydrodynamic interaction between reservoir water and dam-foundation system is implicitly taken into consideration by the Westergaard approach using surface finite elements added to dam-fluid and foundation-fluid interfaces. The concrete material model is used to present the cracking of dam concrete under a seismic load the using smeared crack approach based on the Willam and Warnke failure criterion. The materially nonlinear analysis for both dam concrete and foundation rock is performed using Drucker- -Prager model. According to numerical results, tensile stresses and maximum strains reduce significantly in the materially nonlinear model. In addition, the cracking areas in the dam decrease also when material nonlinearity characteristics of the dam-foundation rock system is considered in analyses

Seismic analysis of Fractured Koyna Concrete Gravity Dam

Seismic analysis of a fractured dam is a generally complex problem. This paper presents an earthquake behavior investigation of a fractured concrete gravity dam considering dam-reservoir-foundation rock interaction. The Koyna dam profile, located in India, is adopted in this study. The nonlinear finite element analyses are conducted taking into account empty and full reservoir cases, to exhibit the hydrodynamic effect of reservoir water on the dam earthquake response. The hydrodynamic pressure is modeled by fluid finite elements based on a Lagrangian approach. Transient analyses take into account material and connection nonlinearity. Drucker-Prager model is employed in nonlinear analyses for the dam concrete and foundation rock. The structural crack between the top and bottom blocks of the dam is presented by surface-to-surface contact elements based on Coulomb’s friction law in order to simulate the behavior of contact joints and deformation of blocks. The distribution of horizontal displacements and principal stresses along the dam height is investigated for empty and full reservoir cases.The failure processes of two potential failure modes of cracked dam, i.e, the separation and sliding of top block during an earthquake, are examined

Phytochemical Profile and Antioxidant Activity of Nigella sativa L Growing in Morocco

Background. Nigella sativa L (NS) is a powerful antioxidant and medicinal plant with many therapeutic applications particularly in traditional medicine for respiratory, gastrointestinal, rheumatic, and inflammatory disorders, as well as cancer. Objective. The aim of this study is to extract the active ingredients from the Moroccan Nigella sativa L and determine its antioxidant properties. We hypothesize that the separation of the compounds from Nigella sativa L has either a positive or negative effect on antioxidants. To study this, we explored different methods to simultaneously extract and separate compounds from Nigella sativa L and performed antioxidant tests (β-carotene and DPPH) for all collected fractions. Methods. Nigella sativa L was hot-extracted by Soxhlet and mother extracts and was separated using silica column chromatography with adequate eluents. Qualitative phytochemical tests to determine the chemical families in Nigella sativa L seeds were performed on the fractions. They were also identified and characterized by GC-MS and HPLC-DAD. Then, antioxidant activity was examined by β-carotene bleaching and DPPH radical scavenger tests. Results and Conclusion. The mother extract hexane FH generated eight different fractions (SH1-8) and the acetone extract FA generated 11 fractions (SA1-11). The FH fractions had a high percentage of fatty acids, and the FA fractions had some interesting polyphenols derivative compounds. Phytochemical screening revealed secondary metabolites such as polyphenols flavonoids, alkaloids, steroids, terpenes coumarins, tannins, and saponins. We found that only two solvents (hexane, acetone) of different polarities could easily extract and simultaneously separate the components of Nigella sativa L. The antioxidant fractions that we collected had close activity to reference compounds but were more active than the corresponding mother extracts. Moreover, several IC50 values of fractions from acetone extract were better than those from hexane. Therefore, the antioxidant activity of Nigella sativa L is more attributed to flavonoids and polyphenols than fatty acids. In summary, the separation of hexane extract presents a more pronounced positive effect for antioxidant tests than acetone extract

Experimental and Co-Simulation Performance Evaluation of an Earth-to-Air Heat Exchanger System Integrated into a Smart Building

International audienceBuilding models and their connected subsystems are often simulatedas standalone entities. However, in order to monitor a system′sreactions to changing parameters and to assess its energyefficiency, it must be exposed to the actual dynamic context of thebuilding under study. Hence, frameworks assessing co-operativesimulation of buildings and their subsystems should be used. Inthis study, the Building Control Virtual Test Bed (BCVTB) frameworkwas used for co-simulation of a small-scale building (EEBLab)connected to an Earth-to-air heat exchanger (EAHE). The EnergyPlustool was used to simulate the indoor air temperature variationswithin the EEBLab, and MATLAB was used to model the EAHE system andto calculate its performance based on various parameters. TheHOLSYS internet of things platform was deployed to monitor andcollect the experimental data from the sensors to validate thesimulations. A favorable agreement between the experimental andsimulation results was obtained, showing the contribution of thesmall-scale EAHE system in maintaining a comfortable indoortemperature range inside EEBLab. Moreover, it demonstrated theeffectiveness and accuracy of the proposed approach for integratedbuilding co-simulation and performance evaluation

Experimental and Co-Simulation Performance Evaluation of an Earth-to-Air Heat Exchanger System Integrated into a Smart Building

Building models and their connected subsystems are often simulated as standalone entities. However, in order to monitor a system′s reactions to changing parameters and to assess its energy efficiency, it must be exposed to the actual dynamic context of the building under study. Hence, frameworks assessing co-operative simulation of buildings and their subsystems should be used. In this study, the Building Control Virtual Test Bed (BCVTB) framework was used for co-simulation of a small-scale building (EEBLab) connected to an Earth-to-air heat exchanger (EAHE). The EnergyPlus tool was used to simulate the indoor air temperature variations within the EEBLab, and MATLAB was used to model the EAHE system and to calculate its performance based on various parameters. The HOLSYS internet of things platform was deployed to monitor and collect the experimental data from the sensors to validate the simulations. A favorable agreement between the experimental and simulation results was obtained, showing the contribution of the small-scale EAHE system in maintaining a comfortable indoor temperature range inside EEBLab. Moreover, it demonstrated the effectiveness and accuracy of the proposed approach for integrated building co-simulation and performance evaluation

A Hybrid Fuzzy Sliding Mode Controller for a Double Star Induction Machine

International audienc