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Abstract: Airborne Lidar (Light detection and ranging) is an efficient tool for the generation of Digital Terrain Models (DTMs). Although many studies have been conducted in generating DTMs using Lidar data, it is still a challenging research area. The difficulty in filtering large buildings as well as a diversity of urban features makes the design of urban DTM generating methods an ongoing priority. This research adopted an upward-fusion methodology to generate urban DTMs using airborne Lidar data. Firstly, several preliminary DTMs of different resolutions were obtained using a local minimum method. Next, upward fusion was conducted between these DTMs. This process began with the DTM of the largest grid size, which was treated as a trend surface. A finer DTM was compared with this large scale DTM. By setting appropriate thresholds, a new DTM was achieved by selecting qualified elevation values from the finer DTM and retaining the value of the trend surface when the value from the finer DTM was beyond the threshold. This process continued iteratively until all preliminary DTMs had been included in the upward fusion and a refined DTM of high resolution was achieved. To further reduce possible errors in the resulting DTM, an extended local minimum method was proposed for filtering outliers and generating preliminary DTMs. A case study was carried out in the city of Cambridge, which represents an urban landscape with a variety of building forms, street patterns and vegetation structures. The time efficiency, results of the accuracy assessments and comparison with leading software proved the success of the case study and indicated that upward-fusion was an effective method for the generation of urban DTMs with airborne Lidar data and could improve the accuracy of other DTM generating algorithms. This paper also proposed possible approaches for further improvements on this methodology. [Copyright &y& Elsevier]

Abstract: Large, single grains of Y–Ba–Cu–O (YBCO) have been batch-processed to date by the top seeded melt growth (TSMG) process using NdBCO or SmBCO seed crystals. It has proved difficult, however, to economically batch-process light rare earth (LRE) LRE–Ba–Cu–O bulk high temperature superconductors, which have higher critical current densities and irreversibility fields than YBCO, and therefore greater potential for high field engineering applications. In this paper, we report a novel batch-process based on a cheap, readily available generic seed crystal, developed recently at Cambridge, and a TSMG melt processing technique based on cold seeding in air for the batch fabrication of Gd–Ba–Cu–O–Ag single grains. The superconducting properties of the (LRE)BCO single grains fabricated by this process are, in all respects, equivalent to those processed more conventionally in a reduced oxygen atmosphere. [ABSTRACT FROM AUTHOR]

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: Transmission electron microscopy (TEM) with in situ ion irradiation is unique amongst experimental techniques in allowing the direct observation of the internal microstructure of materials on the nanoscale whilst they are being subjected to bombardment with energetic particles. Invaluable insights into the underlying atomistic processes at work can be gained through direct investigation of radiation induced and enhanced effects such as: phase changes and segregation; mechanical and structural changes; atomic/layer mixing and chemical disorder; compositional changes; chemical reactions; grain growth and shrinkage; precipitation and dissolution; defect/bubble formation, growth, motion, coalescence, removal and destruction; ionisation; diffusion; and collision cascades. The experimental results obtained can be used to validate the predictions of computational models which in turn can elucidate the mechanisms behind the phenomena seen in the microscope. It is 50years since the first TEM observations of in situ ion irradiation were made by D.W. Pashley, A.E.B. Presland and J.W. Menter at the Tube Investment Laboratories in Cambridge, United Kingdom and 40years since the first interfacing of an ion beam system with a TEM by P.A. Thackery, R.S. Nelson and H.C. Sansom at the Atomic Energy Research Establishment at Harwell, United Kingdom. In that time the field has grown with references in the literature to around thirty examples of such facilities. This paper gives an overview of the importance of the technique, especially with regard to the current challenges faced in understanding radiation damage in nuclear environments; a description of some of the important construction elements and design considerations of TEMs with in situ ion irradiation; a brief history of the development of this type of instrument; a summary of the facilities built around the world over the last half century; and finally a focus on the instruments in operation today. [Copyright &y& Elsevier]

Abstract: Masonry structures may be modelled as an assembly of linearly elastic bodies (individual bricks or stone-blocks) in unilateral frictional contact. Such models generally constitute a formidable computational challenge owing to the need to resolve interactions between individual bodies, such as detection of crack and openings and the resolution of non-linear equations governing the contact. Even for medium size structures, the large number of blocks from which they are assembled renders a full direct simulation of such structures practically impossible. In this paper, an adaptive multi-scale technique for the modelling of large-scale dynamic structures is implemented and applied to the computer simulation of Clare College Bridge, in Cambridge, UK. The adaptive multi-scale approach enables us to carry out simulations at a complexity normally associated with the cost of modelling the entire structure by a simple continuum model whilst incorporating small scale effects, such as openings of gaps and slippage between individual masonry units, using a systematic and locally optimal criterion. [Copyright &y& Elsevier]