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Climate change has become one of the most urgent challenges facing our planet today. The consequences we are gradually experiencing have been driven by human activity. Specifically, the increase in energy demand, met mainly through the combustion of fossil fuels such as coal, oil derivatives and natural gas, has significantly increased greenhouse gas emissions, especially carbon dioxide (CO2), leading to global warming. To address the environmental problems arising from climate change, which we are gradually experiencing, it is clear that the development of the use of renewable energy sources is the key to the transition from fossil fuels to these innovative energy alternatives, in order to achieve zero emissions and contribute to decarbonization. However, the deployment of these clean energies requires the development of systems that guarantee continuous energy production, to overcome interruptions caused by the variability of natural resources like wind, sun, or water. A viable solution to this issue is employing energy storage technologies to correct the mismatch between energy supply and demand. In particular, in the specific case of the use of the sun as a renewable thermal energy source, thermal energy storage (TES) systems are of great interest, since more than half of the energy demanded in industry is thermal energy. Among the different sensible TES media, conventional concrete is emerging as a very attractive option for use as TES due to its low cost, high availability, ease of processing, high specific heat, good mechanical stability at high temperature and excellent operational performance when subjected to thermal cycling. And despite its moderate thermal conductivity, research has shown that incorporating multiple heat exchangers through which the heat transfer fluid (HTF) passes in concrete improves its efficiency, albeit at an increased cost. However, caution should be exercised in the use of concrete as the production of its precursor, Portland cement (PC), is a significant contributor to greenhouse gas emissions, particularly CO2. It is estimated that for every ton of PC produced, approximately one ton of CO2 is released into the atmosphere. For this reason, construction materials must be rethought and one of the lines of research to reduce CO2 emissions is the search for alternative precursors known as supplementary cementitious materials (SCM). SCMs enable the full or partial substitution of PC. Complete replacement of PC leads to the development of alkali-activated materials (AAM), while partial replacements, typically around 70-80%, result in the development of hybrid materials (HM). This Doctoral Thesis involves the fabrication of both alternative cementitious materials, AAM mortars and HM mortars, to investigate their feasibility as TES. Specifically, for both alternatives, the main precursor used as a substitute is blast furnace slag (BFS), an industrial by-product that has proven to be a promising alternative. In the case of the AAM mortar composed of BFS, SLAG, the activation of the precursor is carried out with sodium silicate due to the excellent mechanical properties of the final cementitious material. Nevertheless, the use of solutions makes the workability of these systems difficult, so HM with BFS (HSLAG) are also manufactured, which hydrate in the presence of water. HM mortars are composed of almost 80% BFS, about 20% PC and 5% sodium sulphate to promote the alkaline medium necessary for BFS activation. After verifying through a life cycle analysis (LCA) that alternative mortars offer benefits in terms of carbon footprint and water footprint, as well as continuing to manufacture alternatives focused on PC substitution, the possibility of replacing the natural aggregate with glass waste (GW) is investigated. The substitution of sand is carried out in the three types of mortars (AAM, HM and reference PC) with the aim of reducing water consumption, as sand is the component with the highest water demand. However, only the AAM system, SLAG, allows up to 25% of sand to be replaced by GW (SLAG75), thanks to the high cohesion of its main reaction product, the C-A-S-H gel. When the alternatives are manufactured together with the PC reference mortar, both the compressive mechanical properties and the key thermal properties for a TES, thermal conductivity and specific heat, are evaluated before and after various thermal treatments. After analyzing how the mechanical and thermal properties are affected after thermal treatments −including exposure to constant temperatures and thermal cycling−, it is determined that the alternative systems offer comparable and even superior mechanical stability under temperature exposure than a conventional PC system. In addition, alternative materials, characterized by their thermal conductivity and specific heat, show a superior suitability for TES applications compared to PC. More specifically, the AAM system, SLAG, exhibits operational characteristics superior to PC by reducing heat-up times and increasing its storage capacity, which allows for a reduction in TES volume and a reduction in heat exchanger surface area. While the HM system, HSLAG, does not reach the performance of SLAG, it does offer operational improvements compared to PC. These promising results are attributed to less degradation of the reaction products generated in the alternative mortars and better cohesion between the binder and the aggregate. This last factor had a negative effect on SLAG75, as the weakness in the bond created between the binder and the GW, as well as a greater difference in the coefficients of thermal expansion (CTE), lead to the generation of porosity, and even cracks, which determine both the mechanical and thermal behavior. Thus, when selecting a material such as TES, porosity must be controlled and evaluated as a critical parameter. The results displayed by the PC alternative systems developed in this Doctoral Thesis demonstrate their suitability to be selected as sustainable TES both at low-medium and high temperatures. Consequently, it can be generally concluded that the proposed alternative materials show a promising potential for their application as TES blocks. Thus, further research and development in this field could lead to the widespread adoption of these materials as TES, thus contributing to the transition towards sustainable and renewable energy systems.

Available online 13 October 2023 ; Rising demand for protein-rich foods can impact N₂O emissions from croplands. Recent research has pointed to the role of modified plant vasculature in grain protein increase. Here we highlight how discovering the mechanistic role of plant vasculature in protein improvement and nitrogen-use efficiency could reduce global N₂O emissions. ; Luqman B. Safdar, Ian D. Fisk, and M. John Foulkes

The desire to reduce fuel consumption and gas emissions, along with increasing demands on electrical energy is driving the evolution of vehicle power system architectures well beyond the conventional single alternator and battery. Amongst the different power system architectures available, are mild-hybrid electric architectures. Such architectures may offer flexibility in balancing the trade-offs associated with minimising fuel consumption, and greater capacity to meet electric energy demands. They allow for a wide range of energy management strategies to be investigated. Such strategies are able to accommodate for the need to reduce fuel consumption, undesirable gas emissions, and the need to meet the increased dependence on electrical energy. The strategies can be implemented by vehicle power management systems running energy management algorithms. Such systems are becoming more common in commercial vehicles, however, they are not commonly found in current military vehicles. This thesis focusses on evaluating the impacts caused to vehicle acceleration, fuel consumption, the time to fully charge/discharge the vehicle battery pack, and the electrical conversion efficiency, when introducing energy management strategies into a baseline mild-hybrid electric combat vehicle under different military stationary and moving scenarios. The scenarios were selected because current vehicle manufacturers and academia have primarily focussed on investigating energy management strategies in urban environments. In comparison, a study involving military scenarios allows a new application domain to be investigated. The thesis describes the mild-hybrid electric combat vehicle baseline, and presents the results of comparing the baseline against one that has been extended to include additional energy management strategies under different military scenarios. ; Thesis (MPhil) -- University of Adelaide, School of Electrical and Electronic Engineering, 2018

This study analyzes the relationship between drought processes and crop yields in Moldova, together with the effects of possible future climate change on crops. The severity of drought is analyzed over time in Moldova using the Standard Precipitation Index, the Standardized Precipitation Evapotranspiration Index, and their relationship with crop yields. In addition, rainfall variability and its relationship with crop yields are examined using spectral analysis and squared wavelet coherence. Observed station data (1950–2020 and 1850–2020), ERA5 reanalysis data (1950–2020), and climate model simulations (period 1970–2100) are used. Crop yield data (maize, sunflower, grape), data from experimental plots (wheat), and the Enhanced Vegetation Index from Moderate Resolution Imaging Spectroradiometer satellites were also used. Results show that although the severity of meteorological droughts has decreased in the last 170 years, the impact of precipitation deficits on different crop yields has increased, concurrent with a sharp increase in temperature, which negatively affected crop yields. Annual crops are now more vulnerable to natural rainfall variability and, in years characterized by rainfall deficits, the possibility of reductions in crop yield increases due to sharp increases in temperature. Projections reveal a pessimistic outlook in the absence of adaptation, highlighting the urgency of developing new agricultural management strategies.

The anaerobic bioavailability of two types of solid slaughterhouse waste (poultry and pig wastes) was studied after the application of thermal pretreatment. Both wastes were characterized by different proportions between fats, proteins and carbohydrates. The thermal pretreatments selected (70ºC for 60 min, and 133ºC and 3 bars for 20 min) were included in the European regulations 1774/2002 & 92/2005 for higienization purposes. These pretreatments had a remarkable effect on the solubilization of organic matter and on protein hydrolysis. No negative effects in methane or biogas yields were found in both pretreated wastes, but the bioavailibity of organic matter after the pretreatment depended on the composition of each waste, basically the presence of carbohydrates which could react with protein hydrolysis products (amino acids) giving slowly or not anaerobically biodegradable products (Maillard compounds).

Of all the renewable resources, solar energy has the greatest potential for endingour reliance on fossil fuels. The solar energy that reaches the earth’s surface is 10,000 times the total energy consumption of the planet at any given time and yet we harness only 0.1% of this, mostly as solar-thermal energy. The major limitations of solar energy conversion processes are cost and storage. Strategies for addressing these issues have focused on advanced designs and new materials. Nanomaterials- materials with high surface-to-volume ratios, play a crucial role in the future of this industry. The work of this thesis involved a novel design for a cost-effective, water-splitting system that produces hydrogen - a storable fuel. The system designwas comprised of nanomaterials assembled on a microparticle. Thesis (PhD)--University of South Australia, 2016. Includes bibliographical references.

[Extract] The Fukushima nuclear disaster demonstrated the magnitude of devastation when energy security is prioritized over human security. No doubt, the task of balancing the two needs is immense and difficult trade-offs need to be made at different times. But policy decisions in these two domains cannot be made without adequate consultation with the public, consideration for their preferences, and a shared vision for the future.

ResumenEl entrenamiento con cargas es una actividad anaeróbica glucolítica intensa y se ha comprobado que el error en las estimaciones del gasto energético en esta actividad varía entre un 13 y un 30%. El principal objetivo de este trabajo es describir la contribución anaeróbica de energía en un circuito con cargas. Doce hombres (20-26 años) y diecisiete mujeres (18-29 años) estudiantes de Ciencias de la Actividad Física y del Deporte realizaron un entrenamiento en circuito de cargas a 6 intensidades diferentes (entre el 30% y 80% de su 15RM). Durante la totalidad de los circuitos se registró el gasto energético aeróbico por calorimetría indirecta, la frecuencia cardiaca con pulsómetro Polar® y la concentración de lactato en sangre capilar para medir la contribución anaeróbica. El incremento que produjo la energía anaeróbica se situó entre el 5,1% y un máximo del 13,5%, lo que hace evidente que medir o no la contribución anaeróbica en el entrenamiento en circuito puede provocar un error medio del 9,65%. Existen diferencias significativas (PAbstractResistance training is an intense anaerobic glycolytic activity and has been shown that estimates of energy expenditure in this activity turn out into an error that varies between 13 and 30%. The main aim of this paper is to describe the anaerobic energy contribution in circuit weight training. Twelve men (20-26 years) and seventeen women (18-29 years) students in Science of Physical Activity and Sport performed circuit training at six different intensities (between 30% and 80% of 15RM). During all the circuits aerobic energy expenditure was registered by indirect calorimetry, heart rate with Polar® monitors and lactate concentration in capillary blood to measure the anaerobic contribution. The increased due to anaerobic energy was between 5,1% and a maximum of 13,5%, which clearly means that to measure or not the anaerobic contribution in circuit training can lead to an average error of 9,65%. There are significant differences (P