The design and construction of a microprocessor- based educational computer

Since digital computers came into widespread use in the early 1960's there has been the need to educate Engineers and Scientists in the areas of logic, machine organisation and programming. The computer described is aimed primarily at the teaching of machine organisation while offering useful facilities in the other areas. In the past, machines demonstrating computer architecture have been special purpose machines, they are now rather dated and have proved to be very expensive. The new machine uses a microprocessor to simulate the operation of an educational computer in which the content of all registers and states of gates are simultaneously displayed. The computer has an order code and architecture which is typical of modern small computers and has four modes of operation, viz:- 'Manual' in which individual parts of the machine can be manipulated manually by push buttons. 'One bit' in which the machine will obey an instruction one-step at a time and return to manual mode on completion of the instruction. 'One Instruction' when the machine will carry out the sequence of steps forming an instruction at a selected speed and will return to manual mode on completion of the instruction. 'Continuous' in which the machine obeys sequential instructions taken from the store until it is stopped manually or reaches a 'halt' instruction when it returns to manual mode. While such a computer could be a specially built machine as in the past, use of a microprocessor reduces the display to a series of lamps and push buttons interfaced to the processor and the apparent operation of the computer is determined by the program held in Read-only memory. Thus changes in the architecture of the order code of the educational computer can be achieved by re-writing part or all of the program and it is therefore anticipated that the machine described will be capable of enhancement both easily and cheaply

A Study of the Multihadronic Properties of Photon-Photon Interactions

The analysis described in this thesis concerns the study of hadron production in photon-photon interactions. The data analysed were taken with the CELLO detector on the PETRA storage ring at the DESY physics institute in Hamburg during 1986. During this time the machine operated with a centre of mass energy of 35 GeV and the total recorded integrated luminosity amounted to 86 pb-1. The data studied was split into three Q2 (where the Q2 is the invariant mass of the virtual photon) regions in the range 0 < Q2 < 30 GeV2 consisting of untagged events (with two undetected scattered beam leptons assumed to have been contained in the beam-pipe producing two nearly real photons) and single tagged events (where one beam lepton remain undetected producing a nearly real photon and one detected scattered beam lepton producing a highly virtual photon). Two tagging regions were used. Forward tags were detected in lead-glass scintillators close to the beam axis (55 < theta < 80 mr) and endcap tags were detected in the lead-liquid argon endcaps (150 < theta < 360 mr). The events were required to have ≥ 4 charged tracks and constrained to the hadronic mass WVIS region 4 ≤ WVIS ≤ 9 GeV. This produced three data samples, 15610 untagged events with ~0.1 GeV2, 371 forward tagged events with ~1.0 GeV2 and 302 endcap tagged events with ~12.7 GeV2. The data was compared to an incoherent sum of the quark parton model (QPM) and a soft hadronic term described by a generalised vector dominance model (GVDM). It was found that this gives reasonable overall agreement with the data. The overall numbers of events and their Q2 dependence was found to be in good agreement with an incoherent sum of QPM and a soft hadronic model whose W, Q2 dependence was best modelled by the GVDM ansatz. A jet analysis of the data showed it to be dominated by a two-jet component which was well modelled by the QPM + GVDM term. An excess of events at medium and high jet pt's was observed in the low Q2 data. The inclusion of a phasespace component, or rescaling the QPM component provided a good description of this excess. The thrust of the high jet pt events was described neither by the inclusion of a phasespace term (which underestimates the thrust), nor by scaling the QPM term (which overestimates the thrust). However, a good description of the thrust of high jet pt events was provided by the addition of a multijet term to GVDM + QPM

Molecular dynamics studies of static and dynamic melting points, using numerical modelling and simulated tampers

The pressures required for high energy density physics are achieved experimentally using laser shock compression. This is a dynamic process, with picosecond time scales. Establishing a melt temperature in a dynamic system is made non trivia by overshoot of the melting point due to the kinetic barrier for the phase change. There is therefore a need to be able to model dynamic melt temperatures in such a way that a static melt curve can be predicted, and to link these simulations to an experimental method. By tracking liquid growth to create a numerical melt model, static melt curves of Cu and Ta (in the range 0-10 GPa) were obtained from dynamic heating simulated using molecular dynamics. These were in agreement, within an error of 1%, to literature melt curves and also to the values found using the established static coexistence method, with the computational cost reduced by two orders of magnitude. A typical shock target consists of an ablator, the target material and a tamper. A shock impedance method was developed to model the tamper as a mobile wall which returned the expected release wave through the bulk material. Different tamper materials could therefore be used to alter the cooling rate during release. With Cu as the test material, the literature melt curve (in the range 50-110 GPa) was recreated, with a 7% error in temperature. This method of modelling a tamper in molecular dynamics removes the need to know the potential of the tamper material. Both novel methods developed in this thesis have succeeded in reproducing established static melt curves, by modelling dynamic systems. These methods could be applied to laser shock experiments, in order to verify simulated melt curves at high pressures

Dissolved organic carbon dynamics in a UK podzolic moorland catchment: linking storm hydrochemistry, flow path analysis and sorption experiments

Better knowledge of spatial and temporal delivery of dissolved organic carbon (DOC) in small catchments is required to understand the mechanisms behind reported long-term changes in C fluxes from some peatlands. We monitored two storms with contrasting seasons and antecedent conditions in a small upland UK moorland catchment. We examined DOC concentrations and specific UV absorbance (SUVA at 285 nm), together with solute concentrations required to undertake end-member mixing analyses to define dominant flow paths contributing to streamflow. This was combined with laboratory soil-solution equilibrations. We aimed to resolve how seasonal biogeochemical processing of DOC and flowpath changes in organo-mineral soils combine to affect DOC exported via the stream. An August storm following a dry period gave maximum DOC concentration of 10 mg l&lt;sup&gt;−1&lt;/sup&gt;. Small DOC:DON ratios (16–28) and SUVA (2.7–3.6 l mg&lt;sup&gt;−1&lt;/sup&gt; m&lt;sup&gt;−1&lt;/sup&gt;) was attributed to filtration of aromatic compounds associated with up to 53% B horizon flow contributions. This selective filtration of high SUVA DOC was reproduced in the experimental batch equilibration system. For a November storm, wetter antecedent soil conditions led to enhanced soil connectivity with the stream and seven times greater DOC stream-load (maximum concentration 16 mg l&lt;sup&gt;−1&lt;/sup&gt;). This storm had a 63% O horizon flow contribution at its peak, limited B horizon buffering and consequently more aromatic DOC (SUVA 3.9–4.5 l mg&lt;sup&gt;−1&lt;/sup&gt; m&lt;sup&gt;−1&lt;/sup&gt; and DOC:DON ratio 35–43). We suggest that simple mixing of waters from different flow paths cannot alone explain the differences in DOC compositions between August and November and biogeochemical processing of DOC is required to fully explain the observed stream DOC dynamics. This preliminary evidence is in contrast to other studies proposing hydrological controls on the nature of DOC delivered to streams. Although our study is based only on two storms of very different hydrological and biogeochemical periods, this should promote wider study of DOC biogeochemical alteration in headwaters so that this be better incorporated in modelling to predict the impacts of changes in DOC delivery to, and fate in, aquatic systems

Using the Car in a Fragile Rural Tourist Destination: A Social Representations Perspective

The visitor experience of place is inextricably linked to our ability to travel around an area at will, yet this mobility creates many problems especially in scenic rural areas of the UK. The study presented here attempts to unravel visitors’ experiences of mobility using Moscovici’s social representations approach. Travel diaries were employed to explore visitors’ transport choices and mobility patterns during the peak season in Purbeck, Dorset, UK. Analysis focuses on how such patterns reflect a social representation of mobility and the implications this has for visitor travel at destinations

Reducing car-use for leisure: can organised walking groups switch from car travel to bus and train walks?

This paper deals with the significant leisure travel sector, focusing on the attitudes of organised walking groups towards public transport use. A series of interviews with walking group leaders explored the design of organised walks, and factors affecting journeys to and from start points. The themes presented suggest an overlying group culture involving mainly circular walks, reached by car. The research indicates an underlying engrained dependency on cars to reach walks and a degree of opposition to using public transport, which generally contradicts widely–held attitudes towards protecting the environment. Future research should focus more in depth on the long-term removal of psychological barriers to using public transport for leisure, and persuasive measures aimed at groups

An index-based framework for assessing patterns and trends in river fragmentation and flow regulation by global dams at multiple scales

The global number of dam constructions has increased dramatically over the past six decades and is forecast to continue to rise, particularly in less industrialized regions. Identifying development pathways that can deliver the benefits of new infrastructure while also maintaining healthy and productive river systems is a great challenge that requires understanding the multifaceted impacts of dams at a range of scales. New approaches and advanced methodologies are needed to improve predictions of how future dam construction will affect biodiversity, ecosystem functioning, and fluvial geomorphology worldwide, helping to frame a global strategy to achieve sustainable dam development. Here, we respond to this need by applying a graph-based river routing model to simultaneously assess flow regulation and fragmentation by dams at multiple scales using data at high spatial resolution. We calculated the cumulative impact of a set of 6374 large existing dams and 3377 planned or proposed dams on river connectivity and river flow at basin and subbasin scales by fusing two novel indicators to create a holistic dam impact matrix for the period 1930–2030. Static network descriptors such as basin area or channel length are of limited use in hierarchically nested and dynamic river systems, so we developed the river fragmentation index and the river regulation index, which are based on river volume. These indicators are less sensitive to the effects of network configuration, offering increased comparability among studies with disparate hydrographies as well as across scales. Our results indicate that, on a global basis, 48% of river volume is moderately to severely impacted by either flow regulation, fragmentation, or both. Assuming completion of all dams planned and under construction in our future scenario, this number would nearly double to 93%, largely due to major dam construction in the Amazon Basin. We provide evidence for the importance of considering small to medium sized dams and for the need to include waterfalls to establish a baseline of natural fragmentation. Our versatile framework can serve as a component of river fragmentation and connectivity assessments; as a standardized, easily replicable monitoring framework at global and basin scales; and as part of regional dam planning and management strategies

ECOSSE: Estimating Carbon in Organic Soils - Sequestration and Emissions: Final Report

Background Climate change, caused by greenhouse gas ( GHG) emissions, is one of the most serious threats facing our planet, and is of concern at both UK and devolved administration levels. Accurate predictions for the effects of changes in climate and land use on GHG emissions are vital for informing land use policy. Models which are currently used to predict differences in soil carbon (C) and nitrogen (N) caused by these changes, have been derived from those based on mineral soils or deep peat. None of these models is entirely satisfactory for describing what happens to organic soils following land-use change. Reports of Scottish GHG emissions have revealed that approximately 15% of Scotland's total emissions come from land use changes on Scotland's high carbon soils; the figure is much lower for Wales. It is therefore important to reduce the major uncertainty in assessing the carbon store and flux from land use change on organic soils, especially those which are too shallow to be deep peats but still contain a large reserve of C. In order to predict the response of organic soils to external change we need to develop a model that reflects more accurately the conditions of these soils. The development of a model for organic soils will help to provide more accurate values of net change to soil C and N in response to changes in land use and climate and may be used to inform reporting to UKGHG inventories. Whilst a few models have been developed to describe deep peat formation and turnover, none have so far been developed suitable for examining the impacts of land-use and climate change on the types of organic soils often subject to land-use change in Scotland and Wales. Organic soils subject to land-use change are often (but not exclusively) characterised by a shallower organic horizon than deep peats (e.g. organo-mineral soils such as peaty podzols and peaty gleys). The main aim of the model developed in this project was to simulate the impacts of land-use and climate change in these types of soils. The model is, a) be driven by commonly available meteorological data and soil descriptions, b) able to simulate and predict C and N turnover in organic soils, c) able to predict the impacts of land-use change and climate change on C and N stores in organic soils in Scotland and Wales. In addition to developing the model, we have undertaken a number of other modelling exercises, literature searches, desk studies, data base exercises, and experimentation to answer a range of other questions associated with the responses of organic soils in Scotland and Wales to climate and land-use change. Aims of the ECOSSE project The aims of the study were: To develop a new model of C and N dynamics that reflects conditions in organic soils in Scotland and Wales and predicts their likely responses to external factors To identify the extent of soils that can be considered organic in Scotland and Wales and provide an estimate of the carbon contained within them To predict the contribution of CO 2, nitrous oxide and methane emissions from organic soils in Scotland and Wales, and provide advice on how changes in land use and climate will affect the C and N balance In order to fulfil these aims, the project was broken down into modules based on these objectives and the report uses that structure. The first aim is covered by module 2, the second aim by module 1, and the third aim by modules 3 to 8. Many of the modules are inter-linked. Objectives of the ECOSSE project The main objectives of the project were to: Describe the distribution of organic soils in Scotland and Wales and provide an estimate of the C contained in them Develop a model to simulate C and N cycling in organic soils and provide predictions as to how they will respond to land-use, management and climate change using elements of existing peat, mineral and forest soil models Provide predictive statements on the effects of land-use and climate change on organic soils and the relationships to GHG emissions, including CO 2, nitrous oxide and methane. Provide predictions on the effects of land use change and climate change on the release of Dissolved Organic Matter from organic soils Provide estimates of C loss from scenarios of accelerated erosion of organic soils Suggest best options for mitigating C and N loss from organic soils Provide guidelines on the likely effects of changing land-use from grazing or semi-natural vegetation to forestry on C and N in organic soils Use the land-use change data derived from the Countryside Surveys of Scotland and Wales to provide predictive estimates for changes to C and N balance in organic soils over time

The European Cycle Route Network, EuroVelo

This study evaluates the challenges and opportunities of developing a cycle tourism network across Europe. It focuses on EuroVelo, a network of 12 long-distance routes managed by the European Cyclists’ Federation, which is being developed in different countries by a wide range of partners. The study reviews the market for cycle tourism in Europe and presents a EuroVelo demand modal. It reviews the carriage of cycles on trains. Finally, it evaluates the potential of the Iron Curtain Trail

The European Cycle Route Network, EuroVelo

This update of the 2009 study evaluates the challenges and opportunities of developing a cycle tourism network across Europe. It focuses on EuroVelo, a network of 14 long distance routes managed by the European Cyclists’ Federation which is being developed in different countries by a wide range of partners. The study reviews the market for cycle tourism and presents a model of demand for EuroVelo. It also evaluates the recent developments on the Iron Curtain Trail