Optimizing water supply and hydropower reservoir operation rule curves: An imperialist competitive algorithm approach

Efficient reservoir management requires the implementation of generalized optimal operating policies that manage storage volumes and releases while optimizing a single objective or multiple objectives. Reservoir operating rules stipulate the actions that should be taken under the current state of the system. This study develops a set of piecewise linear operating rule curves for water supply and hydropower reservoirs, employing an imperialist competitive algorithm in a parameterization–simulation–optimization approach. The adaptive penalty method is used for constraint handling and proved to work efficiently in the proposed scheme. Its performance is tested deriving an operation rule for the Dez reservoir in Iran. The proposed modelling scheme converged to near-optimal solutions efficiently in the case examples. It was shown that the proposed optimum piecewise linear rule may perform quite well in reservoir operation optimization as the operating period extends from very short to fairly long periods.     

High-Throughput Exploration of Triple-Cation Perovskites via All-in-One Compositionally-Graded Films

Many devices heavily rely on combinatorial material optimization. However, new material alloys are classically developed by studying only a fraction of giant chemical space, while many intermediate compositions remain unmade in light of the lack of methods to synthesize gapless material libraries. Here report a high-throughput all-in-one material platform to obtain and study compositionally-tunable alloys from solution is reported. This strategy is applied to make all Cs_xMA_yFA_zPbI₃ perovskite alloys (MA and FA stand for methylammonium and formamidinium, respectively), in less than 10 min, on a single film, on which 520 unique alloys are then studied. Through stability mapping of all these alloys in air supersaturated with moisture, a range of targeted perovskites are found, which are then chosen to make efficient and stable solar cells in relaxed fabrication conditions, in ambient air. This all-in-one platform provides access to an unprecedented library of compositional space with no unmade alloys, and hence aids in a comprehensive accelerated discovery of efficient energy materials.     

Chemical Recycling of Polyolefinic Waste to Light Olefins by Catalytic Pyrolysis

Catalytic pyrolysis of post-industrial and post-consumer waste is studied in an auger-type reactor at pilot scale by applying two different zeolites and an amorphous silica-alumina catalyst in-situ at 400–550 °C. Contrary to thermal pyrolysis, of polyolefin-rich waste, high gaseous pyrolysis product yields of approx. 85 wt % are achieved with C₂–C₄ olefin contents of up to 67 wt %. After deactivation by coke deposition catalyst regeneration is proved feasible for maintaining the gaseous product yield and composition. Waste feedstocks with significant nitrogen and halogen heteroatom content are not suitable for in-situ catalytic pyrolysis.     

Circuit breakers in HVDC systems: state-of-the-art review and future trends

High voltage direct current (HVDC) systems are efcient solutions for the integration of large-scale renewable energy sources with the main power grids. The rapid development of the HVDC grid has resulted in a growing interest in DC circuit breakers (DCCBs). A fast and reliable circuit breaker is a necessary requirement in the development of large scale HVDC grids. This paper provides a comprehensive review and survey of the HVDC CBs and discusses potential research directions. Operational principles and the main features of various DCCBs are described and their merits and shortcomings are also highlighted.     

Viscoelastic behaviour effect of hyaluronic acid on reciprocating flow inside mini‐channel

One of the most successful surgeries during the 21^st century is total joint replacement (TJR) with material combination of polymer‐on‐metal (PoM). Despite its success, wear particle generation at the interface of the polymer and metal causes eventually implant loosening. Investigating and understanding the wear particles distribution should help in designing implants with better performances. First step towards characterising wear particle distribution is deriving the lubricant behaviour and velocity distribution inside implant gap. Different hyaluronic acid (HA) solutions were subjected to a sinusoidal movement in straight rectangular channels. The velocity profiles along the channel width were measured with Micro Particle Image Velocimetry. HA solution behaviour was found to be dependent on the concentration. Results showed significant differences between the water (Newtonian) and HA behaviour in unsteady flow. The unsteady behaviour of the lubricant depended strongly on its non‐Newtonian viscoelastic behaviour which was due to the time dependent nature of HA solution. Copyright © 2016 John Wiley & Sons, Ltd.