Infrastructure Engineering - Research Publications
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ItemApplication of nanomaterials in the sustainable built environment(University of Moratuwa, 2010)Nanotechnology is widely regarded as one of the twenty-first century’s key technologies, and its economic importance is sharply on the rise. In the construction industry, nanomaterials has potentials that are already usable today, especially the functional characteristics such as increased tensile strength, self-cleaning capacity, fire resistance, and additives based on nano materials make common materials lighter, more permeable, and more resistant to wear. Nanomaterial are also considered extremely useful for roofs and facades in the built environment. They also expand design possibilities for interior and exterior rooms and spaces. Nano–insulating materials open up new possibilities for ecologically oriented sustainable infrastructure development. It has been demonstrated that nanotechnology has invented products with many unique characteristics which could significantly provide solutions current construction issues and may change the requirement and organization of construction process. This paper examines and documents applicable nanotechnology based products that can improve the sustainable development and overall competitiveness of the construction industry.
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ItemApplication of nano insulation materials in the sustainable built environment(University of Moratuwa, 2010)Nanotechnology is widely being used in the built environment for its advantages in many improved engineering properties of the nano materials. Nano insulating materials open up new possibilities for ecologically oriented sustainable infrastructure development. The most widely used nano material in built environment is for the purpose of insulation to improve the energy efficiency namely in the buildings and dwellings. Nanotechnology has now provided an effective and affordable means to increase energy efficiency in pre-existing buildings as well as new construction by increasing thermal resistance. The major advantage of nano insulation materials is its benefit of translucent coatings which increase the thermal envelope of a building without reducing the square footage. The intrinsic property of nano insulating material is it can be applied to windows to reduce heat transfer from solar radiation due it its thermal resistant property and the translucent property allows diffusing of day light. The nano insulating material has significant advantage in reducing the operational energy aspects of buildings due to its valuable insulating properties. This paper examines applicable nanotechnology based products that can improve the sustainable development and overall competitiveness of the building industry. The areas of applying nano insulating material in building industry will be mainly focused on the building envelope. The paper also examines the potential advantages of using nanotechnology based insulating material in reducing the life cycle energy, reduction of material usage and enhancing the useable life span. The paper also investigates the operational energy by simulation methodology and compares the reduction of operational energy consumption.
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ItemMultiple stable states in hydrological models: An ecohydrological investigation(American Geophysical Union, 2009-03-07)Many physical-based models of surface and groundwater hydrology are constructed without the possibility of multiple stable states for the same parameter set. For such a conceptualization, at the cessation of a transient hydrological disturbance of any magnitude the model will return to the same stable state and thus show an infinite resilience. To highlight and falsify this assumption, a numerical distributed ecohydrological model (coupled hillslope Boussinesq-vertically lumped vadose zone) is presented, in which qualitatively different steady state water table elevations exist for the same parameter set. The multiple steady states are shown to emerge from a positive feedback arising from a reduction in leaf area index (LAI) and thus transpiration, as a saline water table approaches the surface. Limit cycle continuation is also undertaken to quantify the state-space location of the threshold (repellor) between the steady states (attractors) and quantify the resilience. While the model is biophysically simple, it is sufficiently complex to challenge this potentially significant assumption within water resource planning.
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ItemOptimization of a similarity measure for estimating ungauged streamflow(AMER GEOPHYSICAL UNION, 2009-10-17)One approach to predicting streamflow in an ungauged catchment is to select an ensemble of hydrological models previously identified for similar gauged catchments, where the similarity is based on some combination of important physical catchment attributes. The focus of this paper is the identification of catchment attributes and optimization of a similarity measure to produce the best possible ungauged streamflow predictions given a data set and a conceptual model structure. As a case study, the SimHyd rainfall‐runoff model is applied to simulate monthly streamflow in 184 Australian catchments. Initial results show that none of 27 catchment attributes can be safely said to consistently give a better ensemble of models than random selection when used independently of other attributes. This is contrary to prior expectations and indicates the sparseness of information within our database of catchments, the importance in this case of prior knowledge for defining important attributes, and the potential importance of combining multiple attributes in order to usefully gauge similarity. Seven relatively independent attributes are then selected on the basis of prior knowledge. The weight with which each of these attributes contributes to the similarity measure is optimized to maximize streamflow prediction performance across a set of 95 catchments. The other 89 catchments are used to independently test the accuracy of streamflow predictions. Using the optimal set of weights led to marked improvement in the accuracy of predictions, showing that the method, while inferior to local calibration, is superior to alternative methods of model regionalization based on regression and spatial proximity. However, there is evidence of nonuniqueness in the optimal solution and the possibility that the attribute weights are somewhat dependent on the catchments used.
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ItemObject-based classification of ikonos imagery for mapping large-scale vegetation communities in urban areas(MOLECULAR DIVERSITY PRESERVATION INTERNATIONAL-MDPI, 2007-11)Effective assessment of biodiversity in cities requires detailed vegetation maps.To date, most remote sensing of urban vegetation has focused on thematically coarse landcover products. Detailed habitat maps are created by manual interpretation of aerialphotographs, but this is time consuming and costly at large scale. To address this issue, wetested the effectiveness of object-based classifications that use automated imagesegmentation to extract meaningful ground features from imagery. We applied thesetechniques to very high resolution multispectral Ikonos images to produce vegetationcommunity maps in Dunedin City, New Zealand. An Ikonos image was orthorectified and amulti-scale segmentation algorithm used to produce a hierarchical network of image objects.The upper level included four coarse strata: industrial/commercial (commercial buildings),residential (houses and backyard private gardens), vegetation (vegetation patches larger than0.8/1ha), and water. We focused on the vegetation stratum that was segmented at moredetailed level to extract and classify fifteen classes of vegetation communities. The firstclassification yielded a moderate overall classification accuracy (64%, κ = 0.52), which ledus to consider a simplified classification with ten vegetation classes. The overallclassification accuracy from the simplified classification was 77% with a κ value close tothe excellent range (κ = 0.74). These results compared favourably with similar studies inother environments. We conclude that this approach does not provide maps as detailed as those produced by manually interpreting aerial photographs, but it can still extract ecologically significant classes. It is an efficient way to generate accurate and detailed maps in significantly shorter time. The final map accuracy could be improved by integrating segmentation, automated and manual classification in the mapping process, especially when considering important vegetation classes with limited spectral contrast.
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ItemImproved capital procurement through increased use of quantitatively-based decisions(Department of Civil Engineering, National Taiwan University, 2008)The procurement of major capital projects always involves significant risk and uncertainties and this is one of the primary causes for the variations from expected outcomes. This paper outlines the delimitation between strategies for making complex decisions using quantitative analyses as opposed to the techniques and applications currently being used by project and construction managers. Various approaches have been developed and adopted by researchers and practitioners to improve the quality of critical project decisions to maximise benefits. Strategic frameworks and organisational hierarchies are frequently deemed as an optimal solution from the perspective of industrial participants, while numerous researchers indicate decisions with quantitative evidences, underpinned by proper choice of technique, will add additional benefits over current industrial practices. It is asserted that improved decisions can be made through the additional use of quantitative approaches. This paper reports the finding of a study that has identified where the increased use of quantitative approaches may assist project and construction managers and proposes a mechanism to confirm the potential benefits.
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ItemInterpretation of qualitative and quantitative information for project reviews: A fuzzy-based approach for OGC ™ gateway review (GR) colour code system (CCS)(Department of Civil Engineering, National Taiwan University, 2008)Independent project reviews are gaining popularity as a technique to improve project outcomes through the timely identification of outstanding project risks. A common technique is that of a Gateway. The Gateway Review Process (GRP) appraises qualitative and quantitative risks and reports the findings via a Colour Code System (CCS) of Red/Amber/Green (R/A/G). Medium to high risk projects that exceed certain risk thresholds are eligible for GRP. Intuitive recognition of potential risks from the application of CCS is insufficient to determine the value gained from the process. This paper attempts to shed light on a tentative effort to interpret the CCS into numerical descriptions by using fuzzy-based method on a survey outcome. This quantitative interpretation of the CCS would then be adopted to provide a measure and understanding (decision evidence) of the benefits obtained through project review such as GRP.
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ItemQuantification of the contribution of non-structural components to the structural performance of high-rise buildings(Department of Civil Engineering, National Taiwan University, 2008-12-01)Non-structural components (NSCs) such as infill walls, façades, stairs, and windows are normally considered as non-load bearing components in the design of buildings. However, a number of researchers have identified that those so-called NSCs have a significant contribution to the lateral performance of the structure. This paper presents the findings of the investigation into the influence of a variety of NSCs on the performance of typical high-rise framed structures via the observation of the influence of these NSCs on the shear and flexural performance, as well as the lateral stiffness of the structures. Finite element (FE) models have been developed to analyse storey drifts, shear force distributions, bending moment distributions, and joint rotations under different structural configurations. The results of the study indicate a significant decrease of the storey drift can be achieved by including different NSCs to the structural frame. Dramatic changes to both the bending moment and the shear force distributions in the inner columns of the structural frame are resulted from the inclusion of NSCs. However, the influence of these NSCs on the flexural and shear performance of the outer columns of the building is significantly less than that of the inner columns. It is concluded that the enhanced performance of actual buildings by including NSCs provides opportunity for refining of the lateral deflection of the building for the serviceability limit states.
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ItemAssessment of relative accuracy of AHN-2 laser scanning data using planar features(MDPI, 2010)AHN-2 is the second part of the Actueel Hoogtebestand Nederland project, which concerns the acquisition of high-resolution altimetry data over the entire Netherlands using airborne laser scanning. The accuracy assessment of laser altimetry data usually relies on comparing corresponding tie elements, often points or lines, in the overlapping strips. This paper proposes a new approach to strip adjustment and accuracy assessment of AHN-2 data by using planar features. In the proposed approach a transformation is estimated between two overlapping strips by minimizing the distances between points in one strip and their corresponding planes in the other. The planes and the corresponding points are extracted in an automated segmentation process. The point-to-plane distances are used as observables in an estimation model, whereby the parameters of a transformation between the two strips and their associated quality measures are estimated. We demonstrate the performance of the method for the accuracy assessment of the AHN-2 dataset over Zeeland province of The Netherlands. The results show vertical offsets of up to 4 cm between the overlapping strips, and horizontal offsets ranging from 2 cm to 34 cm.
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ItemA preliminary artificial intelligence model for predicting the risk from glass windows subject to airblast overpressure(Construction Publishing House, 2007)