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Due to the pressures caused by the energy crisis, environmental pollution, and international regulations, the largest ship-producing nations are exploring renewable resources, such as wind power, solar energy, and fuel cells to save energy and develop more environmentally-friendly ships. Solar energy has recently attracted a great deal of attention from both academics and practitioners; furthermore, the optimization of energy management has become a research topic of great interest. This paper takes a solar-diesel hybrid ship with 5000 car spaces as its research object. Then, following testing on this ship, experimental data were obtained, a multi-objective optimization model related to the ship’s fuel economy and diesel generator’s efficiency was established, and a partial swarm optimization algorithm was used to solve a multi-objective problem. The results show that the optimized energy management strategy for a hybrid energy system should be tested under different electrical loads. Moreover, the hybrid system’s economy should be taken into account when the ship’s power load is high, and the output power from the new energy generation system should be increased as much as possible. Finally, the diesel generators’ efficiency should be taken into consideration when the ship’s electrical load is low, and the injection power of the new energy system should be reduced appropriately.

The local implications of the well-known flux conservation equations of Morton et al. (Proc. R. Soc. Lond. A, vol. 234, 1956, p.1) for plumes and jets are considered. Given the vertical velocity distributions of a model plume or jet, the divergence-free radial velocity distributions are calculated. It is shown that in general the velocity of the plume boundary is not described by the local total fluid velocity in this way. A two-fluid model tracking the evolution of both ‘plume’ and ‘ambient’ fluid is proposed which resolves this apparent inconsistency and also provides a way of explicitly describing the mixing process within a model plume. The plume boundary acts as a phase boundary across which ambient fluid is entrained, and the plume boundary moves at the velocity of the plume fluid. The difference between the plume-fluid radial velocity and the total fluid velocity quantifies in a natural way the purely horizontal entrainment flux of ambient fluid into the plume across the phase boundary at the plume edge.

In the global context of reducing carbon emissions and shifting towards sustainable modes of urban infrastructure, strategies that provide decentralized access to renewable energy technologies for the urban poor are increasingly promoted. However, while innovative energy technologies are introduced in order to support global targets for sustainability and service-delivery while also directly benefiting low-income households (e.g. by reducing the monetary costs of energy), there is widespread evidence that low-income urban dwellers do not always readily accept these technologies. Typically, the urban poor are blamed for failing to adopt new technologies, with little consideration for underlying socio-cultural causes. Using examples drawn from qualitative research in low-income settlements in Mumbai and Cape Town, this paper demonstrates the role of socio-cultural attitudes and practices in affecting social acceptance of domestic solar energy interventions. Focusing specifically on perceptions of normality and practices of social capital, both of which are connected to collective social influence, the paper reveals how these concepts affect the socio-cultural acceptance of new energy technologies amongst low-income urban dwellers in the global South. Furthermore, we argue that adopting a socio-cultural perspective is a crucial, but often overlooked, aspect of scholarly and policy analyses of, and strategies for, energy transitions in the global South.

Abstract This paper addresses three questions that are relevant to integrating different regional transmission areas. Market integration normally increases the number of competitors and should therefore reduce prices but the first section shows that prices could rise when the number of generator s initially increases. Regulatory effort will also be affected by market integration. If the number of generators in either market is low, then our analysis suggests that the outcome depends on whether the regulators act independently or coordinate. Finally, if markets are gradually combined into larger units, the choice of transmission allocation (coordinated auctions or market coupling) will affect the prospects of making further gains and hence could lead to incomplete reform.

This paper presents a novel method to determine the optimal strategy for the allocation of multiple resistive superconducting fault current limiters (SFCLs) aiming to improve the overall protection of standard power grids. The presented approach allows for the straightforward determination of the optimal resistance of the SFCL, accounting for short circuit events occurring at different locations, by modelling the electro-thermal properties of the SFCL via a temperature dependent E-J power law. This material law, based on previous experimental evidence, allows for the introduction of flux pinning, flux creep, and flux flow properties of the superconducting material within a minimum level of complexity. Thereby, we have observed a distinctive kink pattern in the current limiting profiles of the SFCLs, from which no further reduction of the first peak of the fault current is achieved when a greater resistance is considered, allowing a univocal determination of the optimum SFCL resistance. This peculiarity is not observed when the model for the quench properties of the SFCL is simplified towards an exponential resistance, although the last can be used as an auxiliary process for addressing the first guess on the resistance value required for a specific strategy, as it demands less computing time. We have also determined that for many of the cases studied, i.e., for the combinations between one or more SFCLs installed at different locations, and those subjected to fault events located at different points in the network, the recovery time of the superconducting properties of at least one of the SFCLs can last for more than 5 min, constraining the feasibility of a large-scale deployment of this technology. However, by assuming that the practical operation of the SFCL is assisted by the automatic operation of a bypass switch when the SC material is fully quenched, we have determined that the optimal strategy for the overall protection of power grids of standard topology requires a maximum of three SFCLs, with recovery times of less than a few seconds. This information is of remarkable value for power system operators, as it can establish a maximum investment threshold which ultimately can facilitate making decisions regarding the deployment of SFCL technologies.

This analysis, using published data, compared all land and conserved water use in four beef production systems. A widespread feedlot system and fertilised irrigated pasture systems used similar amounts of land. However, extensive unmodified pasture systems used three times more land, and semi-intensive silvopastoral systems used four times less land, so the highest use was 13 times the lowest. The amount of conserved water used was 64% higher in feedlots with relatively intensive rearing systems than in fertilised irrigated pasture; in extensive unmodified pasture systems, it was 38% and in semi-intensive silvopastoral systems, it was 21% of the fertilised irrigated pasture value, so the highest use was eight times the lowest. If there was no irrigation of pasture or of plants used for cattle feed, the feedlot water use was 12% higher than the fertilised pasture use and 57% higher than that in semi-intensive silvopastoral systems. These large effects of systems on resource use indicate the need to consider all systems when referring to the impact of beef or other products on the global environment. Whilst the use of animals as human food should be reduced, herbivorous animals that consume food that humans cannot eat and are kept using sustainable systems are important for the future use of world resources.

Africa has experienced unprecedented growth across a range of development indices for decades. However, this growth is often at the expense of Africa’s biodiversity and ecosystems, jeopardizing the livelihoods of millions of people depending on the goods and services provided by nature, with broader consequences for achieving the United Nations Sustainable Development Goals. Encouragingly, Africa can still take a more sustainable path. Here, we synthesize the key learnings from the African Ecological Futures project. We report results from a participatory scenario planning process around four collectively-owned scenarios and narratives for the evolution of Africa’s ecological resource base over the next 50 years. These scenarios provided a lens to review pressures on the natural environment, through the drivers, pressures, state, impacts, and responses (DPSIR) framework. Based on the outcomes from each of these steps, we discuss opportunities to reorient Africa’s development trajectories towards a sustainable path. These opportunities fall under the broad categories of “effective natural resource governance”, “strategic planning capabilities”, “investment safeguards and frameworks”, and “new partnership models”. Underpinning all these opportunities are “data, management information, and decision support frameworks”. This work can help inform collaborative action by a broad set of actors with an interest in ensuring a sustainable ecological future for Africa.