Effet de l’hydratation et du rapport E/C sur les paramètres de la rugosité de surface de pâtes cimentaires

Ce travail s'inscrit dans le cadre du projet national à Fond Unique Interministériel, nommé ERGOFORM (ERGOnomic FORMwork-Système de coffrage auto-stable diminuant la pénibilité de chantier), qui vise à mettre au point un procédé de coffrage innovant. Quatre pâtes de ciment ont été élaborées avec des rapports Eau sur Ciment (E/C) de respectivement 0,30, 0,35, 0,40 et 0,45. L'évolution des propriétés physiques et mécaniques des pâtes de ciment ont été mesurées : la porosité accessible à l'eau sous vide, les résistances à la compression et en flexion trois points. L'évolution des paramètres de rugosité en fonction du temps de cure a été analysée par microscopie interférométrique et microscopie électronique à balayage environnemental (MEB-E). Les résultats expérimentaux montrent que l'augmentation du dosage en ciment diminue la porosité accessible à l'eau et améliore les propriétés mécaniques à 24h (après décoffrage nommé T0). L'évolution de la porosité en fonction du temps de cure montre une augmentation se stabilisant après 4 jours d'immersion dans l'eau pour les pâtes cimentaires de rapports E/C de 0,40 et de 0,45 (Groupe 2). En revanche, cette augmentation se prolonge légèrement pour les pâtes de ciment 0,30 et 0,35 (Groupe 1). Par ailleurs, l'évolution des paramètres de rugosité est fonction du dosage en ciment. En effet, les analyses microscopiques et par diffraction des rayons X mettent en évidence une diminution de la quantité des pores en surface, mais aussi l'évolution des paramètres de rugosité par un changement de sa morphologie et la formation de portlandite même après 2 heures de cure normalisée. : The experimental study is part of the national project ERGOnomic FORMwork (Self-Stable Formwork System Reducing Site Difficulty) named ERGOFORM, which aims to develop an innovative formwork process for construction field. Four cement pastes were provided with different water-to-cement ratio (W/C), respectively, 0.30, 0.35, 0.40 and 0.45. The evolution of physical and mechanical properties of cement pastes was measured through water porosity under vacuum, compressive strength and flexural strength. The variation of the roughness parameters was performed by the interferometry microscope. The environmental scanning electron microscopy (E-SEM) was used to analyze the evolution of the surface morphology. The experimental results show that the increase of cement quantity decreases the water porosity and improves the mechanical properties of studied mix designs at 24 hours (after stripping, called T0). The evolution of porosity versus curing time shows that the variation stabilizes after 4 days of immersion in water for the ratio W/C 0.40 and 0.45, named G2 (Group 2). On the other hand, this variation slightly continued for cement pastes 0.30 and 0.35, named G1 (Group 1). Moreover, the evolution of roughness parameters is dependent on cement quantity in mix design. Indeed, the MEB coupling EDX and X-ray diffraction analyzes reveal a decrease in the amount of surface pores, but also the evolution of the roughness parameters by a change in its morphology and the formation of portlandite even after 2 hours of standardized cure

Retinal Structures and Visual Cortex Activity are Impaired Prior to Clinical Vision Loss in Glaucoma

Glaucoma is the second leading cause of blindness worldwide and its pathogenesis remains unclear. In this study, we measured the structure, metabolism and function of the visual system by optical coherence tomography and multi-modal magnetic resonance imaging in healthy subjects and glaucoma patients with different degrees of vision loss. We found that inner retinal layer thinning, optic nerve cupping and reduced visual cortex activity occurred before patients showed visual field impairment. The primary visual cortex also exhibited more severe functional deficits than higher-order visual brain areas in glaucoma. Within the visual cortex, choline metabolism was perturbed along with increasing disease severity in the eye, optic radiation and visual field. In summary, this study showed evidence that glaucoma deterioration is already present in the eye and the brain before substantial vision loss can be detected clinically using current testing methods. In addition, cortical cholinergic abnormalities are involved during trans-neuronal degeneration and can be detected non-invasively in glaucoma. The current results can be of impact for identifying early glaucoma mechanisms, detecting and monitoring pathophysiological events and eye-brain-behavior relationships, and guiding vision preservation strategies in the visual system, which may help reduce the burden of this irreversible but preventable neurodegenerative disease. © The Author(s) 2016111121sciescopu

Media społecznościowe w zarządzaniu reklamą polityczną : studium Indii

Social Media has become an important tool of opinion formation in this technology driven age and marketing managers have realised its significance. With political arena behaving like a customer driven market, uses of marketing technologies are increasingly being used for competitive advantage. Social Media has proved to a useful tool. Marketing political parties are evident in the recent election in India. The present paper explores the implication of twitter on political marketing by studying the relationship between tweet followers and vote share gained by political parties taking Delhi Assembly elections 2015 as a case in point. The findings suggest that there is a positive correlation between the volume of tweet and vote share.Media społecznościowe w tej erze napędzanej technologią stały się ważnym narzędziem kształtowania opinii i menedżerowie marketingowi zdali sobie sprawę z jej znaczenia. Z areną polityczną zachowującą się jak rynek napędzany klientem, użytkownicy technologii marketingowych są coraz częściej wykorzystywani do przewagi konkurencyjnej. Media społecznościowe okazały się do tego użytecznym narzędziem. Marketingowe partie polityczne są widoczne w ostatnich wyborach w Indiach. Niniejszy artykuł bada wpływ Twittera na marketing polityczny, badając relacje między osobami obserwującymi twittera i udziałem głosów uzyskanych przez partie polityczne, biorące udział w wyborach Zgromadzenia Delhi w 2015. Wnioski sugerują, że istnieje dodatnia korelacja pomiędzy ilością wysyłanych tweetów a udziałem głosów

Novel COVID-19 Based Optimization Algorithm (C-19BOA) for Performance Improvement of Power Systems

The ongoing pandemic due to novel coronavirus disease-2019 (COVID-19) has rapidly unsettled the health sector with a considerable fatality rate. The main factors that help minimize the spread of this deadly virus are the proper use of masks, social distancing and antibody growth rate in a person. Based on these factors, we propose a new nature-inspired meta-heuristic algorithm named COVID-19 Based Optimization Algorithm (C-19BOA). The proposed C-19BOA mimics the spread and control behavior of coronavirus disease centered on three containment factors: (1) social distancing, (2) use of masks, and (3) antibody rate. Initially, the mathematical models of containment factors are presented, and further, the proposed C-19BOA is developed. To ascertain the effectiveness of the developed C-19BOA, its performance is verified on standard IEEE mathematical benchmark functions for the minimization of these benchmark functions and convergence to the optimal values. These performances are compared with established bio-inspired optimization algorithms available in the literature. Finally, the developed C-19BOA is applied on an electrical power system load–frequency–control model to test its effectiveness in optimizing the power system parameters and to check its applicability in solving modern engineering problems. A performance comparison of the proposed C-19BOA and other optimization algorithms is validated based on optimizing the controller gains for reducing the steady-state errors by comparing the effective frequency and tie-line power regulation ability of an industrially applied Proportional–Integral–Derivative controller (PID) and Active Disturbance Rejection controller (ADRC). Moreover, the robustness of C-19BOA optimized PID and ADRC gains is tested by varying the system parameters from their nominal values

Evaluating the Optimal Electric Vehicle Location for a Hybrid Energy System Controlled with Novel Active Disturbance Rejection Controller

Power system control is an important issue with regard to power system safety, flexibility, and reliability. Over the years, various new power system control strategies have been explored, but the main disadvantage of these control strategies is their complexity in structures with respect to industrially applied PID controller. The present paper introduces a novel control strategy based on modified disturbance rejection control, which is a modification of the PID controller that not only preserves the simplicity of control design but also offers an effective control based on state observer-based control law. The proposed control strategy addresses some basic limitations of a PID controller and implements modified control law to remove these limitations. In order to prove the effective control of the proposed control strategy, a standard IEEE-39 bus power system integrated with renewable energy generations is developed, and a comparative analysis of the proposed controller is performed with respect to its ancestor controllers. The comparison is validated based on the system dynamic responses like frequency and tie-line power deviations when the power system is subjected to different disturbances. Furthermore, the power system is integrated with electric vehices (EVs) in vehicle-to-grid (V2G) mode in order to ascertain the effect of EVs when used in V2G mode. A novel study is carried out in which the optimal location of EVs in the power system is determined based on the enhancement in stability of the power system by EVs. The analyses are carried out in MATLAB Simulink software. Simulation reports reflect the optimal control action of the proposed controller with respect to already established strategies projected in the literature. Moreover, the results illustrate that EVs when connected in Area 1 and Area 3 of the power system, the system deviations and steady-state errors are much less as compared to the other cases

Novel COVID-19 Based Optimization Algorithm (C-19BOA) for Performance Improvement of Power Systems

The ongoing pandemic due to novel coronavirus disease-2019 (COVID-19) has rapidly unsettled the health sector with a considerable fatality rate. The main factors that help minimize the spread of this deadly virus are the proper use of masks, social distancing and antibody growth rate in a person. Based on these factors, we propose a new nature-inspired meta-heuristic algorithm named COVID-19 Based Optimization Algorithm (C-19BOA). The proposed C-19BOA mimics the spread and control behavior of coronavirus disease centered on three containment factors: (1) social distancing, (2) use of masks, and (3) antibody rate. Initially, the mathematical models of containment factors are presented, and further, the proposed C-19BOA is developed. To ascertain the effectiveness of the developed C-19BOA, its performance is verified on standard IEEE mathematical benchmark functions for the minimization of these benchmark functions and convergence to the optimal values. These performances are compared with established bio-inspired optimization algorithms available in the literature. Finally, the developed C-19BOA is applied on an electrical power system load–frequency–control model to test its effectiveness in optimizing the power system parameters and to check its applicability in solving modern engineering problems. A performance comparison of the proposed C-19BOA and other optimization algorithms is validated based on optimizing the controller gains for reducing the steady-state errors by comparing the effective frequency and tie-line power regulation ability of an industrially applied Proportional–Integral–Derivative controller (PID) and Active Disturbance Rejection controller (ADRC). Moreover, the robustness of C-19BOA optimized PID and ADRC gains is tested by varying the system parameters from their nominal values