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Non-stationary methods of flood frequency analysis are widespread in research but rarely implemented by practitioners. One reason may be that research papers on non-stationary statistical models tend to focus on model fitting rather than extracting the sort of results needed by designers and decision makers. It can be difficult to extract useful results from non-stationary models that include stochastic covariates for which the value in any future year is unknown. We explore the motivation for including such covariates, whether on their own or in addition to a covariate based on time. We set out a method for expressing the results of non-stationary models as an integrated flow estimate, which removes the dependence on the covariates. This can be defined either for a particular year or over a longer period of time. The methods are illustrated by application to a set of 375 river gauges across England and Wales. We find annual rainfall to be a useful covariate at many gauges, sometimes in conjunction with a time-based covariate. For estimating flood frequency in future conditions, we advocate exploring hybrid approaches that combine the best attributes of non-stationary statistical models and simulation models that can represent changes in climate and river catchments. [ABSTRACT FROM AUTHOR]

This paper discusses the impact of housing affordability on the spatial distribution of productivity and wages. The key theoretical contribution is to phrase the problem as an issue of the composition (rather than the level) of housing demand and link it to heterogeneous preferences and characteristics of households. Using a simple simulation methodology, the study estimates levels of amenity values and wages that would make current house prices as affordable as they were in 1995 in all English local authority districts. Although average wages would be unlikely to increase if housing was more affordable, productivity across England would probably be higher as the spatial distribution of economic activity would change. The key conclusions are that (1) unaffordable housing has significant economic implications; and (2) policy aimed at improving housing affordability should consider targeting housing demand as well as supply. [ABSTRACT FROM AUTHOR]

Abstract: Climate change is a global problem and across the world the transport sector is finding it difficult to break projected increases in carbon dioxide (CO2) emissions; there are very few contexts where deep reductions in transport CO2 emissions are being made. A number of research studies are now examining the potential for future lower CO2 emissions in the transport sector. This paper develops this work to consider some of the wider sustainability impacts (economic, social and local environmental) as well as the lower CO2 transport impacts of different policy trajectories. Hence the central argument made is for an integrated approach to transport policy making over the longer term – incorporating scenario analysis and multi-criteria assessment (MCA) – to help assess likely progress against a range of objectives. The analysis is based on work carried out in Oxfordshire, UK. Different packages of measures are selected and two scenarios developed which satisfy lower CO2 aspirations, one of which also provides wider positive sustainability impacts. A simulation model has been produced to help explore the strategic policy choices and tensions evident for decision-makers involved in local transport planning. The paper argues for a ‘strategic conversation’ () at the sub-regional and city level, based upon future scenario analysis and MCA, discussing the priorities for intervention. Such an approach will help us examine the scale of change and trade-offs required in moving towards sustainable transport futures. [Copyright &y& Elsevier]

Abstract: This paper highlights the growing need for a realistic crowd simulation in the design of large venues such as concert halls and stadia. A discrete element method (DEM) technique for modelling crowd dynamics has been developed that represents each person within the model as 3 overlapping circles, a position, orientation and velocity in 2D. Contact forces between elements are included in the model as well as psychological forces, motive forces and moments. The motion of each person is then modelled in a Newtonian manner with a numerical integration time-stepping scheme. The model has been shown previously to work well in predicting egress. In this paper the predicted model behaviour is compared to actual video footage shot at various locations around University Park Campus, Nottingham. It did not match well to the video footage when people are moving towards each other, as in cases of contra-flow on a walkway. In order to improve the model, a general algorithm for ‘avoidance’ was included which appeared to make the model significantly more realistic in these cases. The paper also shows areas for further potential development, such as incorporating people into associative groups such as family or friends. [Copyright &y& Elsevier]

The following paper reiterates the importance of studying past visibility patterns within the context of landscape archaeology. In spite of the many difficulties and criticisms revolving around this topic, efforts aimed at reconstructing these patterns and exploring their possible roles are considered to be central to the reconstruction of social landscapes. This paper extends previous GIS work done on inter-visibility by making reference to the concept of "co-visibility," by exploring the way in which visibility of any monument or set of monuments is shared with that of other monuments. A subset of round barrows from the Yorkshire Wolds (northern England) is used to illustrate this work. The study also underlines the need to address the variability which is often present in archaeological data, variability, in this case, of visibility patterns associated with the barrows due to our lack of precise chronological information. [ABSTRACT FROM AUTHOR]

Abstract: London is expected to experience more frequent periods of intense rainfall and tidal surges, leading to an increase in the risk of flooding. Damp and flooded dwellings can support microbial growth, including mould, bacteria, and protozoa, as well as persistence of flood-borne microorganisms. The amount of time flooded dwellings remain damp will depend on the duration and height of the flood, the contents of the flood water, the drying conditions, and the building construction, leading to particular properties and property types being prone to lingering damp and human pathogen growth or persistence. The impact of flooding on buildings can be simulated using Heat Air and Moisture (HAM) models of varying complexity in order to understand how water can be absorbed and dry out of the building structure. This paper describes the simulation of the drying of building archetypes representative of the English building stock using the EnergyPlus based tool ‘UCL-HAMT’ in order to determine the drying rates of different abandoned structures flooded to different heights and during different seasons. The results are mapped out using GIS in order to estimate the spatial risk across London in terms of comparative flood vulnerability, as well as for specific flood events. Areas of South and East London were found to be particularly vulnerable to long-term microbial exposure following major flood events. [Copyright &y& Elsevier]

Positioning using the Global Positioning System (GPS) is unreliable in dense urban areas with tall buildings and/or narrow streets, known as ‘urban canyons’. This is because the buildings block, reflect or diffract the signals from many of the satellites. This paper investigates the use of 3-Dimensional (3-D) building models to predict satellite visibility. To predict Global Navigation Satellite System (GNSS) performance using 3-D building models, a simulation has been developed. A few optimized methods to improve the efficiency of the simulation for real-time purposes were implemented. Diffraction effects of satellite signals were considered to improve accuracy. The simulation is validated using real-world GPS and GLObal NAvigation Satellite System (GLONASS) observations.The performance of current and future GNSS in urban canyons is then assessed by simulation using an architectural city model of London with decimetre-level accuracy. GNSS availability, integrity and precision is evaluated over pedestrian and vehicle routes within city canyons using different combinations of GNSS constellations. The results show that using GPS and GLONASS together cannot guarantee 24-hour reliable positioning in urban canyons. However, with the addition of Galileo and Compass, currently under construction, reliable GNSS performance can be obtained at most, but not all, of the locations in the test scenarios. The modelling also demonstrates that GNSS availability is poorer for pedestrians than for vehicles and verifies that cross-street positioning errors are typically larger than along-street due to the geometrical constraints imposed by the buildings. For many applications, this modelling technique could also be used to predict the best route through a city at a given time, or the best time to perform GNSS positioning at a given location. [ABSTRACT FROM AUTHOR]

Abstract: A computer based building simulation model was developed to examine the energy load and environmental management in The National Archives Q1 repository building in Kew, UK to optimise environmental management and examine the impacts of climate change. The need to accurately simulate the hygrothermal environment inside the archive building which houses mainly paper-based records led to the choice of EnergyPlus as the modelling software. The study presents the simulation results of five environmental strategies which predict energy saving potential as high as 43% without significantly affecting the quality of the preservation environment. The effect of climate change is predicted to have little impact on the archive environment due to the filtering effect of the air conditioning system. On the other hand, an increase in total energy load by 15% and 24% is predicted under the worst case climate change scenario in 2050 and 2080, respectively, if the current environmental management practice is continued into the future. However, the identified energy saving strategies could represent possible mitigative solutions in reducing future energy load against the impact of climate change. [Copyright &y& Elsevier]

Power systems usually support disturbances which may initiate a cascading event that could cause total or partial blackouts. Vulnerability assessment is made in order to establish mechanisms that reduce the risk of blackouts. This paper presents a novel approach for assessing vulnerability of an Electric Power System. For this purpose, several indices, that reflect the health of the system, are calculated and the grid is partitioned in electric areas depending on bus electric coherency. The indices allow assessing four different symptoms of system stress such as voltage instability, poorly- damped power oscillations, frequency deviations outside limits, and overloads. The combination of these indices yields a vulnerability index using a fuzzy inference system. The vulnerability index is an indicator of the health of each electric area. The methodology is tested in the 39 bus New England test system via time domain simulations. The results show that vulnerability begins to develop in a specific region of the system, so its assessment and ranking can be used to coordinate and focus control actions that mitigate the consequences of the disturbances and reduce the risk of cascading events and system blackouts. [ABSTRACT FROM AUTHOR]

This paper discusses computer simulation modelling in the context of environmental risk management. Approaching computer simulation as practice, performed in networks of heterogeneous elements, we examine the modelling undertaken by engineering consultants commissioned to provide knowledge about local flood risk to the Environment Agency of England and Wales (EA), the public body responsible for flood risk management. We propose that this simulation modelling is best understood as a form of engineering, work geared to solving the problems of clients. It is also a 'virtual' activity, articulating risks and possibilities in the digital space of the computer. We find that this 'virtual engineering' is shaped by the demands and protocols of the EA, first, by the establishment of long-term contractual agreements for delivering knowledge and second, by an EA requirement to use particular software packages. Fashioned between long-term contracts and black-boxed software virtual engineering becomes stabilised as 'the' way in which knowledge about flood risk in actual localities is generated and, consequently, becomes 'hard-wired' into flood risk management in England. [ABSTRACT FROM AUTHOR]

Summary: Although no single weather-related event can be directly attributed to climate change, new techniques make it possible to estimate how much the chance of an event has been altered by anthropogenic emissions. This paper looks at the floods that occurred in England in Autumn/Winter 2000, by using large ensembles of 1-year climate model simulations representing April 2000–March 2001. These represent an industrial climate and four estimates of an hypothetical non-industrial climate (without historical greenhouse gas emissions), and are used to drive hydrological models for eight catchments in England. The simulated flows are used to assess the impact of historical emissions on the chance of occurrence of extreme floods in each catchment, through calculation of the fraction of attributable risk (FAR). Combining results for the four non-industrial climates, positive median values of FAR indicate that, for all but one catchment, emissions are likely to have led to an increased chance of flooding in the October–December period. Definitive conclusions are difficult however, as there are wide bands of uncertainty in FAR, with distributions generally spanning no attributable difference in risk (FAR =0). One catchment shows a decreased flood chance (negative median FAR), due to its high permeability, but an analysis of the effect of antecedent conditions shows that a longer period of climate data than 1year is probably required to obtain more representative values of FAR for such catchments. The inclusion of snowfall/snowmelt is also shown to be important for floods over the October–March period, as the reduced likelihood of snowmelt-induced floods in the warmer temperatures of the industrial climate moderates the increased flood chance due to other sources of flooding. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a meanline model to predict the performance parameters of a turbocharger turbine under steady state conditions. The turbine was developed at Imperial College and the design was based on a commercial nozzleless unit that was modified into a variable geometry single-entry turbine. The wide range of tests data from the Imperial College Turbocharger Group dynamometer enabled the evaluation of the model in the areas of the turbine map where currently no previous comparison had been made in the literature. This facility is designed to allow testing over a wide range of velocity ratios (0.3–1.1) previously unavailable with conventional test stands. The nozzleless turbine model was validated against experimental results spanning an equivalent speed range of 27.9 and 53.8rev/s√K while for the nozzled case the model was validated against one single speed (43.0rev/s√K) and three different vane angle settings (40°, 60° and 70°). The results of the model simulation showed that the performance can be predicted with excellent accuracy for different turbine speeds and vane angles. Based on the model prediction, a breakdown aerodynamic loss was performed. [Copyright &y& Elsevier]

Abstract: This paper investigates pedestrian exposure to traffic emissions at the Marylebone Road–Gloucester Place intersection in central London, taking a particular interest in the peak exposures occurring within minutes. The approach is based on the large eddy simulation modelling methodology, which enables high spatial resolution of air movements and pollutant concentrations to be achieved at relatively moderate computational cost. The results show the complexity of the air flows in the vicinity of the intersection at pedestrian height and the large variability of peak exposures due to the turbulent air flows. [Copyright &y& Elsevier]

Abstract: This paper investigates occupant behaviour of window-use in night-time naturally ventilated offices on the basis of a pilot field study, conducted during the summers of 2006 and 2007 in Cambridge, UK, and then demonstrates the effects of employing night-time ventilation on indoor thermal conditions using predictive models of occupant window-use. A longitudinal field study shows that occupants make good use of night-time natural ventilation strategies when provided with openings that allow secure ventilation, and that there is a noticeable time of day effect in window-use patterns (i.e. increased probability of action on arrival and departure). We develop logistic models of window-use for night-time naturally ventilated offices, which are subsequently applied to a behaviour algorithm, including Markov chains and Monte Carlo methods. The simulations using the behaviour algorithm demonstrate a good agreement with the observational data of window-use, and reveal how building design and occupant behaviour collectively affect the thermal performance of offices. They illustrate that the provision of secure ventilation leads to more frequent use of the window, and thus contributes significantly to the achievement of a comfortable indoor environment during the daytime occupied period. For example, the maximum temperature for a night-time ventilated office is found to be 3°C below the predicted value for a daytime-only ventilated office. [Copyright &y& Elsevier]

Abstract: Traditionally, researchers have employed statistical methods to model crime. However, these approaches are limited by being unable to model individual actions and behaviour. Brantingham and Brantingham (1993) described that in their opinion a useful and productive model for simulating crime would have the ability to model the occurrence of crime and the motivations behind it both temporally and spatially. This paper presents the construction and application of an agent-based model (ABM) for simulating occurrences of residential burglary at an individual level. It presents a novel framework that allows both human and environmental factors to be simulated. Although other agent-based models of crime do exist, this research represents the first working example of integrating a behavioural framework into an ABM for the simulation of crime. An artificial city, loosely based on the real city of Leeds, UK, and an artificial population were constructed, and experiments were run to explore the potential of the model to realistically simulate the main processes and drivers within this system. The results are highly promising, demonstrating the potential of this approach for both understanding processes behind crime and improving policies and developing effective crime prevention strategies. [Copyright &y& Elsevier]

Abstract: This study investigates Box–Jenkins (BJ), autoregressive with external inputs (ARX), autoregressive moving average with external inputs (ARMAX) and output error (OE) models to identify the thermal behaviour of an office positioned in a modern commercial building in London. These models can all be potentially used for improving the performance of the thermal environment control system. External and internal climate data, recorded over the summer, autumn and winter seasons, were used to build and validate the models. The paper demonstrates the potential of using linear parametric models to predict room temperature and relative humidity for different time scales (30min or 2h ahead). The prediction performance is evaluated using the criteria of goodness of fit, coefficient of determination, mean absolute error and mean squared error between predicted model output and real measurements. The results demonstrate that all models provide reasonably good predictions but the BJ model outperforms the ARMAX and ARX models. [Copyright &y& Elsevier]

Abstract: This paper demonstrates the application of Terrestrial Laser Scanning (TLS) to determine the full population of grain roughness in gravel-bed rivers. The technique has the potential to completely replace the need for complex, time-consuming manual sampling methods. Using TLS, a total of 3.8 million data points (mean spacing 0.01 m) were retrieved from a gravel bar surface at Lambley on the River South Tyne, UK. Grain roughness was extracted through determination of twice the local standard deviation (2σ z ) of all the elevations in a 0.15 m radius moving window over the data cloud. 2σ z values were then designated to each node on a 5 cm regular grid, allowing fine resolution DEMs to be produced, where the elevation is equivalent to the grain roughness height. Comparisons are made between TLS-derived grain roughness and grid-by-number sampling for eight 2 m2 patches on the bar surface. Strong relationships exist between percentiles from the population of 2σ z heights with measured a-, b-, and c-axes, with the closest matches appearing for the c-axis. Although strong relationships exist between TLS-derived grain roughness (2σ z ), variations in the degree of burial, packing and imbrication, results in very different slope and intercept exponents. This highlights that conventional roughness measurement using gravel axis length should be used with caution as measured axes do not necessarily represent the actual extent to which the grain protrudes into the flow. The sampling error inherent in conventional sampling is also highlighted through undertaking Monte Carlo simulation on a population of 2000 clasts measured using the grid-by-number method and comparing this with the TLS-derived population of grain roughness heights. Underestimates of up to −23% and overestimates of up to +50% were found to occur when considering the D 84, and −20% and overestimates of up to +36% were found to occur when considering the D 50. [Copyright &y& Elsevier]

Abstract: X-ray phase contrast imaging solves the basic problem of conventional X-ray imaging, i.e. low image contrast arising from small absorption differences. For years X-ray phase contrast imaging was thought to be restricted to synchrotron radiation facilities, but a new approach was recently developed at UCL which makes synchrotron-like phase effects achievable with conventional sources, by introducing two separate sets of appropriately designed coded-apertures at either side of the imaged object. Although most proposed applications of X-ray phase contrast imaging are focused on medical aspects, substantial advantages can be gained in other fields, including security inspections. In this case the system has to be based around higher X-ray energies, which has an impact on the system design. This paper describes such a design. A previously developed and experimentally validated simulation program was used to estimate the image contrast that can be expected from a range of details of interest in security inspections imaged under various conditions, including beam spectrum, detector characteristics, coded-aperture design, source-to-sample and sample-to-detector distances, etc.—while taking into account the interplay between these different parameters. The conditions providing maximum image contrast were chosen and used in the ultimate system design. [Copyright &y& Elsevier]

Summary: This paper compares two Monte Carlo sequential data assimilation methods based on the Kalman filter, for estimating the effect of measurements on simulations of state error variance made by a one-dimensional hydrodynamic model. The first method used an ensemble Kalman filter (EnKF) to update state estimates, which were then used as initial conditions for further simulations. The second method used an ensemble transform Kalman filter (ETKF) to quickly estimate the effect of measurement error covariance on forecast error covariance without the need to re-run the simulation model. The ETKF gave an unbiased estimate of EnKF analysed error variance, although differences in the treatment of measurement errors meant the results were not identical. Estimates of forecast error variance could also be made, but their accuracy deteriorated as the time from measurements increased due in part to model non-linearity and the decreasing signal variance. The motivation behind the study was to assess the ability of the ETKF to target possible measurements, as part of an adaptive sampling framework, before they are assimilated by an EnKF-based forecasting model on the River Crouch, Essex, UK. The ETKF was found to be a useful tool for quickly estimating the error covariance expected after assimilating measurements into the hydrodynamic model. It, thus, provided a means of quantifying the ‘usefulness’ (in terms of error variance) of possible sampling schemes. [Copyright &y& Elsevier]

An approach that incorporates three modelling components has been developed to estimate road traffic CO2 emissions for an urban area with street level resolution. The first component enables the determination of the road traffic characteristics using the SATURN (Simulation and Assignment of Traffic in Urban Road Networks) model. The output from this component is then analysed using MATrix LABoratory (MATLAB) programming to provide estimates of CO2 emissions for the urban area. Finally, ArcGIS is used to illustrate the model output. The three components are integrated using a Loose-Coupling approach in which the individual components each load the necessary data to give an independent output. The model structure is discussed in the current paper and the modelling results for a small city (Norwich, UK) are presented. [Copyright &y& Elsevier]

Abstract: This paper develops a new agent-based simulation model to improve discrete choice analysis as well as to analyse the effects of a road user charging scheme for the Upper Derwent Valley in the Peak District National Park. The advantages of discrete choice analysis are well known. However, results with these conventional methods can be biased if interaction effects are significant. The combined approach of the Minority Game, in which agents try to choose the option of the minority side, and discrete choice analysis is appropriate to deal with the problem. The main data was collected by stated preference survey. The agent-based model has four sub-modules: (1) multinomial mixed logit model for mode choice, (2) binary logit model for parking location choice, (3) Markov queue model for parking network, and (4) the Minority Game for parking congestion and learning. The results show that the road user charging scheme reduces car demand in the Upper Derwent Valley. The model also shows that an exemption will increase the utility of elderly visitors. In conclusion, the simulation model demonstrated that oversimplification in conventional discrete choice analysis gave significant biases when real world problems were analysed. [Copyright &y& Elsevier]

The present paper reports the results of a series of parametric and correlation studies that have been conducted on a longwall coal district climatic prediction planning model developed at the University of Nottingham. The results of these simulation exercises have been correlated against continuously recorded climatic survey data collected from longwall coal districts at two representative deep UK coal mines. The survey data used was continuously measured to record the climate across the longwall districts during both weekday production periods and weekend non-production periods. An analysis of the measured data was able to establish average dry and wet bulb temperatures, which characterised the climate within the workings during weekday production and weekend non-production periods. To determine the major contribution that the geothermal properties of the surrounding rock mass have on the heat transfer to the ventilating air stream, a series of climatic simulation and correlation exercises were conducted to establish a base line data set for these parameters during non-production periods. A second series of parametric and correlation exercises were conducted on the longwall climatic simulation model to identify the range of values to be taken by the parameters governing the contribution of heat transfer from the installed electrical machinery and cut mineral during the weekday production periods. It is concluded that these exercises were able to identify a base set of values for the model input parameters that enabled the longwall climatic models to satisfactorily replicate the climatic conditions experienced across two representative UK deep mine longwall districts during production and non-production periods. [ABSTRACT FROM AUTHOR]

Abstract: This paper uses simulation techniques to examine the transport implications of superstore location. In particular it argues that policies for superstore location advocated by central government in the United Kingdom would, if implemented, have had the effect of increasing the distances travelled for such shopping, have reduced access by public transport and on foot, and have increased the amount of travel through built up urban areas. The simulation outcomes are related to a brief case study of superstore locations in East Kent. [Copyright &y& Elsevier]