Theoretical and experimental study of the orientational ordering in the field-induced intermediaite phase from the SmC*FI2 phase in chiral smectic liquid crystals

Under an electric field, chiral smectic liquid crystals transit usually to the unwound SmC* phase where the helical structure is completely unrolled. Sometimes the sample transits initially towards an intermediate polar state before the total destruction of the helix. Based on the extension of the H-T model, a theoretical study of these field-induced phase transitions was carried out. Two hypotheses of the dynamics that give rise to the appearance of the intermediate phase have been discussed. The results of a numerical analysis confirm the known experimental results; the intermediate phase has a three-layer periodicity structure

Understanding the origin of Paris Agreement emission uncertainties

The UN Paris Agreement puts in place a legally binding mechanism to increase mitigation action over time. Countries put forward pledges called nationally determined contributions (NDC) whose impact is assessed in global stocktaking exercises. Subsequently, actions can then be strengthened in light of the Paris climate objective: Limiting global mean temperature increase to well below 2 °C and pursuing efforts to limit it further to 1.5 °C. However, pledged actions are currently described ambiguously and this complicates the global stocktaking exercise. Here, we systematically explore possible interpretations of NDC assumptions, and show that this results in estimated emissions for 2030 ranging from 47 to 63 GtCO2e yr-1. We show that this uncertainty has critical implications for the feasibility and cost to limit warming well below 2 °C and further to 1.5 °C. Countries are currently working towards clarifying the modalities of future NDCs. We identify salient avenues to reduce the overall uncertainty by about 10 percentage points through simple, technical clarifications regarding energy accounting rules. Remaining uncertainties depend to a large extent on politically valid choices about how NDCs are expressed, and therefore raise the importance of a thorough and robust process that keeps track of where emissions are heading over time

Energy Sector Adaptation in Response to Water Scarcity

Integrated assessment models (IAMs) have largely ignored the impacts of water scarcity on the energy sector and the related implications for climate change mitigation. However, significant water is required in the production of energy, including for thermoelectric power plant cooling, hydropower generation, irrigation for bioenergy, and the extraction and refining of liquid fuels. With a changing climate and expectations of increasing competition for water from the agricultural and municipal sectors, it is unclear whether sufficient water will be available where needed to support water-intensive energy technologies (e.g., thermoelectric generation) in the future. Thus, it is important that water use and water constraints are incorporated into IAMs to better understand energy sector adaptation to water scarcity. The MESSAGE model has recently been updated with the capability to quantify the water consumption and withdrawal requirements of the energy sector and now includes several cooling technologies for addressing water scarcity. These new capabilities have been used to quantify water consumption, water withdrawal, and thermal pollution associated with pre-existing climate change mitigation scenarios. The current study takes the next step by introducing water constraints into Shared Socioeconomic Pathway (SSP) scenarios to examine whether and how the energy sector can adapt to water scarcity. This study will provide insight into the following questions related to energy sector adaptation to water scarcity: How does the energy sector adapt to water scarcity in different regions? What are the costs associated with adaptation to water scarcity? How do adaptations to constraints on water withdrawal and consumption differ? Is climate mitigation limited under water scarcity (esp. with low deployment of wind/ solar)? How important are dry cooling and seawater cooling for addressing water scarcity and climate mitigation

Energy Sector Adaptation in Response to Water Scarcity

Integrated assessment models (IAMs) have largely ignored the impacts of water scarcity on the energy sector and the related implications for climate change mitigation. However, significant water is required in the production of energy, including for thermoelectric power plant cooling, hydropower generation, irrigation for bioenergy, and the extraction and refining of liquid fuels. With a changing climate and expectations of increasing competition for water from the agricultural and municipal sectors, it is unclear whether sufficient water will be available where needed to support water-intensive energy technologies (e.g., thermoelectric generation) in the future. Thus, it is important that water use and water constraints are incorporated into IAMs to better understand energy sector adaptation to water scarcity. The MESSAGE model has recently been updated with the capability to quantify the water consumption and withdrawal requirements of the energy sector and now includes several cooling technologies for addressing water scarcity. These new capabilities have been used to quantify water consumption, water withdrawal, and thermal pollution associated with pre-existing climate change mitigation scenarios. The current study takes the next step by introducing water constraints into Shared Socioeconomic Pathway (SSP) scenarios to examine whether and how the energy sector can adapt to water scarcity. This study will provide insight into the following questions related to energy sector adaptation to water scarcity: How does the energy sector adapt to water scarcity in different regions? What are the costs associated with adaptation to water scarcity? How do adaptations to constraints on water withdrawal and consumption differ? Is climate mitigation limited under water scarcity (esp. with low deployment of wind/ solar)? How important are dry cooling and seawater cooling for addressing water scarcity and climate mitigation

Energy sector water use implications of a 2°C climate policy

Quantifying water implications of energy transitions is important for assessing long-term freshwater sustainability since large volumes of water are currently used throughout the energy sector. In this paper, we assess direct global energy sector water use and thermal water pollution across a broad range of energy system transformation pathways to assess water impacts of a 2 °C climate policy. A global integrated assessment model is equipped with the capabilities to account for the water impacts of technologies located throughout the energy supply chain. The model framework is applied across a broad range of 2 °C scenarios to highlight long-term water impact uncertainties over the 21st century. We find that water implications vary significantly across scenarios, and that adaptation in power plant cooling technology can considerably reduce global freshwater withdrawals and thermal pollution. Global freshwater consumption increases across all of the investigated 2 °C scenarios as a result of rapidly expanding electricity demand in developing regions and the prevalence of freshwater-cooled thermal power generation. Reducing energy demand emerges as a robust strategy for water conservation, and enables increased technological flexibility on the supply side to fulfill ambitious climate objectives. The results underscore the importance of an integrated approach when developing water, energy, and climate policy, especially in regions where rapid growth in both energy and water demands is anticipated

Seismic performance of reinforced concrete frame structures strengthened with FRP laminates using a reliability-based advanced approach

Effectiveness of applying FRP-strengthening to enhance the seismic performance of a RC frame structure is studied in this paper. The performance is expressed in term of reliability which implies calculation of the probability to reach the required level of performance under specified loadings and environmental conditions. The proposed approach was applied to a typical three-storey RC frame structure. Two strengthening configurations are compared: applying flexural FRP-strengthening to members – beams/columns – and/or applying FRP-confinement to columns of the structure. Seismic reliability assessments are presented in term of fragility estimates which involves performing nonlinear time history analysis to record the maximum lateral top drift of the RC frame structure under seismic loadings. This analysis is carried out using finite elements method. To reduce the computational effort, an efficient meta-modelling method based on Polynomial Dimensional Decomposition PDD in conjunction with the Monte-Carlo Simulation is developed. Results of simulations demonstrate the efficiency and computational advantages of the proposed method for the seismic reliability assessment of RC frame structures. Furthermore, the results confirm a significant increase in reliability of RC-frames subjected to seismic due to FRP-flexural/FRP-confinement strengthening especially in case of applying FRP-flexural strengthening

Reliability under Seismic Loads of RC Structures Strengthened with FRP using Polynomial Dimensional Decomposition approximation

The present study aims to estimate effectiveness of applying FRP strengthening in order to enhance the seismic structural reliability of RC frames. Two FRP strengthening configurations were compared: applying flexural FRP strengthening to members – beams/columns – of the RC frame and applying FRP confinement to columns of the frame. Seismic reliability was expressed in term of fragility estimates which involves performing nonlinear time history analysis recoding the maximum lateral top drift as a dynamic demand. A nonlinear time history analysis was carried out using finite elements method FEM. In order to reduce the computational effort, an efficient meta-modeling using Polynomial Dimensional Decomposition PDD in conjunction with the Monte-Carlo Simulation (MCS) was used. In addition, a sensitivity analysis using Sobol indices and Morris screening method were applied to evaluate importance of each random variables considered in the analysis . The proposed approach was applied to a typical three-story RC frame. Numerical results demonstrate the efficiency and computational advantages of the proposed meta-model using PDD for the seismic reliability assessment of structures. Furthermore, it was found that enhancement in seismic reliability corresponds to flexural type is quite higher than that corresponds to confining type

SURFACE MODIFICATION OF SILICA NANOPARTICLES BY MEANS OF SILANES: EFFECT OF VARIOUS PARAMETERS ON THE GRAFTING REACTIONS

The adsorption of four silanes, namely: N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), 3-methacryloxypropyltrimethoxysilane (MPTMS), allyltrimethoxysilane (ATMS), N-2-[(N-vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane hydrochloride (CVBS) onto the surface of silica nanoparticles has been studied using water/ethanol (5/95, v/v) mixture. Four experimental parameters were explored for the grafting of the silanes: pH, concentration, time, and temperature. Possible interactions between the silanes and the surface of silica were investigated by means of FT-IR Spectroscopy. The FT-IR analyses confirmed the effectiveness of the silanization of the silica surface. The amount of the adsorbed silane on the silica nanoparticles appeared to be influenced by the initial concentration of the silane, pH, time and temperature of modification

Assessing the challenges of global long-term mitigation scenarios

The implications of global mitigation to achieve different long-term temperature goals (LTTGs) can be investigated in integrated assessment models (IAMs), which provide a large number of outputs including technology deployment levels, economic costs, carbon prices, annual rates of decarbonisation, degree of global net negative emissions required, as well as utilisation levels for fossil fuel plants. All of these factors can be considered in detail when judging the real-world feasibility of the mitigation scenarios produced by these models. This study presents a model inter-comparison of three widely used IAMs (TIAM, MESSAGE and WITCH) to analyse multiple mitigation scenarios exploring a range of LTTGs and a range of constraints, including delayed mitigation action, limited end-use electrification and delayed deployment of carbon capture technologies. The scenario outputs across the three models are examined and discussed and a matrix of the different factors concerning scenario feasibility is presented