Characterisation of the cascode gate drive of power MOSFETs in clamped inductive switching applications

This thesis proposes a novel gate drive circuit to improve the switching performance of MOSFET power switches in power electronic converters. The proposed topology exploits the cascode configuration, allowing the minimisation of switching losses in the presence of practical circuit constraints, which enables efficiency and power density improvements. Switching characteristics of the new topology are investigated and key mechanisms that control the switching process are identified. Unique analysis tools and techniques are also developed to demonstrate the application of the cascode gate drive circuit for switching performance optimisation

Projections of emissions and removals from the LULUCF sector to 2050

Summary for policy makers: • The UK reports projections for the Land Use, Land Use Change and Forestry (LULUCF) sector to inform policy concerning domestic and international climate change commitments. The full projections data are available on the NAEI website (http://naei.defra.gov.uk/reports/reports?report_id=927) • LULUCF activities can result in net annual emissions or removals of greenhouse gases, and changes in carbon stocks in the pools associated with LULUCF. This report provides projections at the UK and Devolved Administration (DA) level, with separate estimates for Scotland, England, Wales and Northern Ireland, which are summed to give the UK totals. The results presented here are based on the reporting conventions of the UNFCCC. They are not presented as potential future accounted emissions and removals under the Kyoto Protocol which are calculated formally at the end of each commitment period. • LULUCF is divided into six land use types: Forest Land (4A), Cropland (4B), Grassland (4C), Wetlands (4D), Settlements (4E), Other Land (4F). Carbon stock changes from Harvested Wood Products are reported in an additional category, Harvested Wood Products (4G). The code refers to the IPCC (2006 Guidelines) inventory category of LULUCF. There is a separate inventory sector – not presented here – dedicated to other emissions, mainly methane and nitrous oxide, from agricultural activities. • Projections are made for net emissions and removals of greenhouse gases to 2050, arising from LULUCF activities reported in the latest (1990-2014) greenhouse gas inventory, for the DAs and the UK excluding Overseas Territories and Crown Dependencies. • Five scenarios (Baseline 1, Baseline 2, Central, Low and Stretch) have been described. The scenarios were developed by BEIS, Defra and the Forestry Commission and have been updated in 2016 following discussions with all of the UK administrations. The scenarios take account of current land use policies and aspirations. The Baseline scenarios are based on climate change-related and forestry policies extant in July 2009. • The main results are: At a UK level, the LULUCF sector has been a net sink since 1990 and is predicted to remain so under all scenarios until at least 2050, although at a declining level from the mid-2020s onwards (depending on the scenario). At a DA level, England and Scotland remain net sinks under all scenarios Wales is a small net sink under the Stretch scenario, but will become an increasing net source under the other scenarios between 2034 and 2049. Northern Ireland is a small net source (except in 1998 and 1999) under the Baseline and Central scenarios, but will become a small net sink from the late 2030s onwards under the Stretch and Low scenarios. The LULUCF sector in the UK and in each of the DAs is dominated by CO2 emissions and removals, although N2O emissions also make a significant contribution. The Forest Land, Cropland and Grassland categories determine the trend in the UK and DAs. The main changes in the projections since the 1990-2013 projections are: Forestry - a methodological revision of the forest carbon accounting model CARBINE to assign carbon stock changes to the correct reporting year, and the inclusion of the National Forest Inventory data (including, for the first time, small woods between 0.1 and 0.5 hectares in size) increasing tree cover and forest carbon stocks (this differs from the submitted 1990-2014 inventory). Grassland - the revision of the emission factor used for grassland on drained organic soils has reduced the size of the grassland sink

The development of an approach to assess critical loads of acidity for woodland habitats in Great Britain

International audienceAlongside other countries that are signatories to the UNECE Convention Long Range Transboundary on Air Pollution, the UK is committed to reducing the impact of air pollution on the environment. To advise and guide this policy in relation to atmospheric emissions of sulphur and nitrogen, a critical load approach has been developed. To assess the potential impact of these pollutants on woodland habitats a steady state, simple mass balance model has been parameterised. For mineral soils, a Ca:Al ratio in soil solution has been used as the critical load indicator for potential damage. For peat and organic soils critical loads have been set according to a pH criterion. Together these approaches have been used with national datasets to examine the potential scale of acidification in woodland habitats across the UK. The results can be mapped to show the spatial variability in critical loads of the three principal woodland habitat types (managed coniferous, managed broadleaved/ mixed woodland and unmanaged woodland). The results suggest that there is a wide range of critical loads. The most sensitive (lowest) critical loads are associated with managed coniferous followed by unmanaged woodland on peat soils. Calculations indicate that at steady state, acid deposition inputs reported for 1995?1997 result in a large proportion of all the woodland habitats identified receiving deposition loads in excess of their critical load; i.e. critical loads are exceeded. These are discussed in relation to future modelled depositions for 2010. Whilst significant widespread negative impacts of such deposition on UK woodland habitats have not been reported, the work serves to illustrate that if acid deposition inputs were maintained and projected emissions reductions not achieved, the long-term sustainability of large areas of woodland in the UK could be compromised. Keywords: critical loads, acid deposition, acidification, woodland, simple mass balance model, sustainabilit

Biodiversity 2020: climate change evaluation report

In 2011, the government published Biodiversity 2020: A strategy for England’s wildlife and ecosystem services [1]. This strategy for England builds on the 2011 Natural Environment White Paper - NEWP [2] and provides a comprehensive picture of how we are implementing our international and EU commitments. It sets out the strategic direction for biodiversity policy between 2011-2020 on land (including rivers and lakes) and at sea, and forms part of the UK’s commitments under the ‘the Aichi targets’ agreed in 2010 under the United Nations Convention of Biological Diversity’s Strategic Plan for Biodiversity 2011-2020 [3]. Defra is committed to evaluating the Biodiversity 2020 strategy and has a public commitment to assess climate change adaptation measures. This document sets out the information on assessing how action under Biodiversity 2020 has helped our wildlife and ecosystems to adapt to climate change. Biodiversity 2020 aims to halt the loss of biodiversity and restore functioning ecosystems for wildlife and for people. The outcomes and actions in Biodiversity 2020, although wider in scope, aimed to increase resilience of our wildlife and ecosystems in the face of a changing climate. In order to inform the assessment, we have defined which of the measurable outputs under Biodiversity 2020 contribute to resilience. Biodiversity 2020 included plans to develop and publish a dedicated set of indicators to assess progress towards the delivery of the strategy. The latest list (at the time of writing), published in 2017, contains 24 biodiversity indicators [4] that would help inform progress towards achieving specific outcomes, they are also highly relevant to the outputs (detailed below) that form the basis for this evaluation. The Adaptation Sub-Committee’s 2017 UK Climate Change Risk Assessment Evidence Report [5] sets out the priority climate change risks and opportunities for the UK. The ASC also produced a review of progress in the National Adaptation Programme - “Progress in preparing for climate change” [6], which highlights adaptation priorities and progress being made towards achieving them. The UK Government’s response to the ASC [7] review includes a set of recommendations, of which Recommendation 6 states that “Action should be taken to enhance the condition of priority habitats and the abundance and range of priority species”. The recommendation further iterated that “This action should maintain or extend the level of ambition that was included in Biodiversity 2020” and that “An evaluation should be undertaken of Biodiversity 2020 including the extent to which goals have been met and of the implications for resilience to climate change.” To this, end an evaluation process has been put in place to define: a. What worked and why? Which actions or activities have had the greatest benefit in terms of delivering the desired outcomes? And, conversely, what prevented progress? b. Where are the opportunities? What are the financial, political, scientific and social opportunities for furthering the desired outcomes in the future? These objectives underpin the evaluation process for actions to date, and will also inform future actions and the iteration of a new nature strategy for England

Regulating services

No abstract available

Revised valuation of flood regulation services of existing forest cover to inform natural capital accounts

This report provides updated evidence on the value of existing woodland in England, Scotland and Wales in regulating flood flows and reducing flood risk in downstream communities. This is a ground-breaking area of analysis that is attempting to improve on what was previously a significant evidence gap in the economic value of woodland. The study updates a previous evaluation (Broadmeadow et al., 2018) with improved estimates for the volume of flood water potentially removed by woodland or retained by its hydraulic roughness. The impacts of woodlands are compared with two alternative land uses, short grass and bare soil. The scope of the analysis was also extended to include the contribution of conifer woodlands, small woodlands, and trees outside of woodlands. A companion report (Fitch et al., 2022) is available that applies the approach to other natural capital types, including woodland, although values are not directly comparable due to methodological differences

The natural capital of floodplains: management, protection and restoration to deliver greater benefits

Key Messages • This review of scientific literature has shown that semi-natural floodplain habitats are a vitally important component of the UK’s natural capital. • They provide a wider range of goods and services than intensive arable/horticultural crops. • The dearth of such habitats in functioning floodplains reduces our resilience to floods and drought, reduces the abundance of pollinating insects and natural pest control agents, and reduces the potential for carbon sequestration and water quality improvements. • Floodplains occupy only 5% of land area in the UK, yet targeted investment here would yield massive savings and gains for society as a whole

Detecting phenology change in the mayfly Ephemera danica: responses to spatial and temporal water temperature variations

1. Rising water temperatures under climate change are expected to affect the phenology of aquatic insects, including the mayfly Ephemera danica Müller which is widespread throughout Europe. 2. To assess temporal and spatial variability in mayfly emergence, E. danica were monitored at two thermally contrasting reaches in the River Dove, English Peak District over the period 2007–2013. Inter-annual variations in growing degree days (GDDs) were modelled for an upstream site with intermittent spring flow supplementing main channel flow (Beresford Dale) and downstream site dominated by near constant discharges of cool groundwater (Dovedale). 3. A strong association exists between the emergence cycle of E. danica and GDDs at each site. Beresford Dale accumulated on average 374 more GDDs than Dovedale. After warm summers E. danica emerged after only 1 year in Beresford Dale but began to revert to a bi-annual cycle after the particularly wet/cool year of 2012. In Dovedale, E. danica maintained a 2-year cycle throughout the monitoring period in spite of the phenology changes observed 8 km upstream. 4. Data from the present study suggest that habitats near cool groundwater may provide important refugia for populations of insects, potentially delaying permanent shifts in phenology under climate change. However, an ability to detect changes in the thermal triggers and phenological response may be hindered by conventional spot sampling protocols