We address the problem of developing a well-performing and implementable scheduler of users with wireless connections to the central controller, which arise in areas such as mobile data networks, heterogeneous networks, or vehicular communications systems. The main feature of such systems is that the quality of each user's channel is time-varying due to fading. The evolution of the channel over its quality states thus causes a time-varying transmission rate of each user. We consider Markovian channel dynamics, relaxing the common but unrealistic assumption of i.i.d. channels. We first focus on three-state channels and show that threshold policies (of giving higher priority to users with higher transmission rate) are not necessarily optimal. For the general case we design a scheduler which generalizes the recently proposed Potential Improvement (PI) scheduler, which gives priority to the users who are unlikely to improve their actual transmission rate soon by much. We propose two practical approximations of PI, whose performance is analyzed and compared to existing alternative schedulers in a variety of simulation scenarios. Our computational experiments indicate that the variant of PI, which only relies on the steady-state distribution of the channel, is robust and performs extremely well, and therefore we recommend its use for practical implementation.

By 2020, the UK is legally obliged to meet 20% of its electrical demands with renewable sources [1]. Currently, renewable sources account for as little as 5%, meaning drastic action is required to meet this target [2]. The UK is also committed to reduce CO 2 emissions by 60% by 2050 [3]. Using clean energy is not just important to help combat climate change, but also to allow the UK to have more control on its energy. With the decline of the North Sea oil and gas industry, there is more and more reliance on importing these fuels through costly negotiations. Furthermore, being in control of our energy sources and especially with renewable energy, the cost for electricity can be stable and independent of any price fluctuations or politics. The UK is fortunate with an abundance of renewable energy options, including the greatest potential for tidal energy in the world. This type of energy holds an important advantage over other forms of renewable energypredictability. With comprehensive tide data for years in advance, any tidal energy project can have a known output the national grid is able to plan for. The successful utilisation of tidal energy alone could provide in excess of 20% of the nations energy demand [4]. The repeated proposals for the Severn barrage since the 1920's have proved the necessity to evolve techniques used for tidal range generation, with each proposal turned down due to high costs and environmental concerns [5-7]. Other UK sites that have been investigated for a barrage scheme also include the Solway [8,9], Mersey [10], Loughor, Duddon, Wyre and Thames Estuaries [11]. However, unlike Swansea Bay lagoon, these projects are not currently progressing. Currently the most advanced project in the UK is the Swansea Bay Tidal lagoon, which is making rapid progress and will hopefully be generating electricity in 2019. The power generated would be able to provide energy for approximately 155,000 homes [12]. As the project is the first of its kind in the world, its construction would send a clear statement of the UK's commitment to clean, renewable energy. The aim of this paper is to bring together the current and existing information regarding tidal lagoon developments while focusing specifically on the planned Swansea Bay Lagoon. 2 Background/Tidal Lagoons Tidal lagoons are a new concept based on the adaptation of an existing, proven technologytidal barrages. Like any tidal range project the success is heavily dependant on the chosen location and with Swansea Bay being part of the

a b s t r a c tThe Archimedes pump is one of the oldest feats of engineering still being used today. In recent times, it has seen a major revival in modern engineering, by reversing it for use as a turbine. This is now an established turbine, being used in Europe since 1994. It has been found this new turbine device has a plethora of advantages over current existing devices, with the simplicity and robustness that has kept the pump in use for centuries acting in its favour. Most existing design theory is for use as pump; however there are many key differences between operation as a pump or turbine, such as the direction the water flows through the device. With further research for turbine operation alone required.The Archimedes Screw turbine currently has a variety of operational modes: inclined, horizontal or submerged. These new devices have the possibility to unlock a wide range of applications. The submerged tidal stream device can operate in low flow velocities (1 m/s) that current devices are unable to. The inclined and horizontal turbines offer greatly reduced environmental effects and can be used in areas previously passed over because of delicate habitats. However, there are still more potential uses, for example in tidal range or tidal fence situations, although research for use in these methods are currently only in the initial stages with Computational Fluid Dynamics (CFD) simulations and scale modelling required to prove the validity.

With the largest part of diversity in the world absorbed by invertebrates, ignoring invertebrates in biodiversity surveys and monitoring of areas under conservation would give a strongly incomplete image. The poor knowledge of most invertebrate taxa and their enormous diversity limits most surveys to the better-studied groups. Hawkmoths (Lepidoptera: Sphingidae) are one of the more charismatic and well-known groups among the Lepidoptera and hence a valuable group commonly used in biodiversity research. In this small-scale study, 42 museum specimens of sphingids from Cusuco National Park (Cortés, Honduras) were identified and compared to recent published accounts. This yielded three new country records and, in addition, four new regional records for the park. Some of the additions to the Honduran fauna probably result from recent taxonomic changes. However, the several contributions using a small collection of this well-studied group in an area which has attracted previous research interest, demonstrate the incomplete data availability and the necessity for more rigorous surveying. Several new records concern high altitude species, indicating the data gap in mountains. As elevation is an important determinant of sphingid community structure, sampling across an altitudinal range is recommended. This study also underpins the usefulness of a reference collection-based approach in particular, as many hawkmoth species are identified using subtle diagnostic characters.The size and attractiveness of its representatives have made the hawkmoths (Lepidoptera: Sphingidae) one of the better studied groups of lepidopterans, with monographs dating M. P. M. Vanhove (&) Á M. Jocque Á J. Casteels BINCO vzw,