No description available.

This research constructs and tests a model of the organisation of building projects for maximum benefit to clients. The model is developed from systems theory, independently of conventional organisational assumptions. It is based upon the premise that the process to be managed must be identified before organisational structures can be designed and it recognises the influence of environmental forces upon projects. The model proposes that the process of building provision consists of sub-systems created by decision points and identifies the interdependency and hence the differentiation within and between the subsystems. The major propositions of the model are that; a) there should be a match of differentiation and integrative effort, b) the operating and managing systems should be differentiated, c) the managing system itself should be undifferentiated and, d) the client and process of building provision should be integrated. The model was tested against three commercial buildings for private clients. Data is presented from interviews and other sources and is interpreted using Linear Responsibility Analysis, which was adapted and developed in this research. The testing method examines the overall compatibility of the model and the test projects, and also identifies the causes of deficiencies in the outcomes of the projects and whether they can be explained by divergence of the projects from the model. The model was found to be valid for the type of project used in the tests. It provides a theoretical framework against which the effectiveness of organisation structures for the management of building projects can be predicted and which can be used for the design of such structures. It is suggested that Linear Responsibility Analysis provides a useful tool for organisation analysis and design. Finally, implications of the results for the organisation of building projects in practice are discussed.

This work addresses the use of an electromagnetic wave sensor to determine moisture content within building fabrics. Building materials that require a special mixing ratio such as concrete, mortar and membrane layers will be subject to significant effects when exposed to unpredictable weather changes owing to the excess of the acceptable moisture content. The acceptable moisture content level varies with various building fabrics and exceeding this level will affect the overall performance of building constructions. The project proposes using a novel electromagnetic (EM) sensor to monitor, in a non-destructive manner, the signal reflected from building structures in real time to determine exceeded moisture content level. This project involves the design and construction of an EM sensor operating at two frequency ranges: 2GHz to 6GHz and 6GHz to 12GHz at a power of 0dBm. This research is a new approach for monitoring moisture in buildings which has not been investigated before. The simulation software High Frequency Structure Simulator (HFSS) was used to model the microwave sensor. The pyramidal horn antenna was chosen as the preferred antenna for this work owing to higher gain, directivity and overall performance. Different building materials and structures have been made in a laboratory environment to determine the levels of moisture content, as well as to determine the modes of building fabrics failures owing to membrane failure, a pipe burst and ground source. Finally, a graphical user interface was developed and used to control the sensor parameters as well as frequency sweep, to capture the data from the sensor. Based on the findings of this project, the EM wave sensor could be used to determine the moisture content of building fabrics in a non-destructive manner.

Buildings represent more than 40% of final global energy consumption, among which 50%-60% of energy consumption is attributed to Heating, Ventilation and Air Conditioning (HVAC) systems. The application of phase change material emulsions (PCMEs) in air conditioning systems is considered to be a potential way of saving energy because with their relatively higher energy storage capacity, they are able to reduce flow rate whilst delivering the same amount of cooling energy. PCMEs can also simultaneously act as cold energy storage to shift peak-load to off-peak time and improve coefficient of performance of systems. However, one of the main barriers affecting the application of PCME is the difficulty in maintaining stability in the emulsions without experiencing any temperature stratification during phase change process. To this end, an innovative energy efficient phase change emulsion has been developed and evaluated. The emulsion (PCE-10) which consists of an organic PCM (RT10) and water has a phase change temperature range of 4-12°C with heat capacity of twice as much as that of water thus making it a good candidate for cooling applications. Particular attention was also paid to the selection of the surfactant blends of Tween60 and Brij52 since they are capable of minimizing the effect of sub-cooling as well as ensuring stability of the emulsion. For the purpose of testing the performance of developed PCE-10 in fin-and-tube heat exchangers, series of theoretical and experimental studies have been carried out to understand the rheological behaviour and heat transfer characteristics of the developed PCE-10 in a fin-and-tube heat exchanger. Both experimental and theoretical results were fairly close and showed that the PCE-10 did enhance the overall heat transfer rate of the heat exchanger. In order to evaluate the potential of the integrated system, whole building energy simulation was carried out with a building simulation code TRNSYS. It was found out that the required volumetric flow rate of PCE-10 was 50% less than that of water which is equivalent to 7% reduction in total energy consumption when providing the same amount of cooling power. Despite its potential in cooling systems, the viscosity of the developed sample was found to be much higher than water which could contribute to high pressure drop in a pumping system. Its thermal conductivity was also found to be about 30% lower than the value for water which could influence heat transfer process. There is therefore the need to enhance these thermophysical properties in any future investigations.

Decision making during the adoption of Building Information Modelling (BIM) in current AEC projects is believed as a key element to improve both BIM performance and project outcome. In order to provide the most informed decision and strategic plan, two vital elements are required: a comprehensive set of decision making criteria and a reasonable priority system. The literature analysis has revealed that existing assessment frameworks have limitations concerning these two elements. Therefore, this research has been designed to develop a more effective BIM evaluation Framework (BeF), to assist new BIM users and also provide a more effective implementation approach for BIM. In order to accomplish this objective, research steps of theoretical and empirical nature have been adopted: (a) a multi-dimensional BIM implementation Framework (BiF) was proposed based on the literature review; (b) use of a case study to test the proposed BiF on a real-life project; (c) a questionnaire approach to test the comprehensiveness of the proposed BiF on an industry level; (d) applying the Delphi method to further refine the proposed criteria in a specific context; (e) using the Analytical Hierarchy Process (AHP) to develop a BeF and providing priority shifting for a more preferable strategic goal in Arup ShenZhen office (ASZ); (f) developing a validation system to prove the efficacy of the proposed BeF. The adoption priority and approach of BIM could be influenced by policies, culture, business structure, legislation etc. As a result, a specific context, China has been selected for this work. The research result could assist decision making in BIM management in the ASZ for a higher BIM performance. The framework by the Delphi method is suitable for the selected context: China. The proposed Delphi and AHP methodological framework can be replicated to assist decision making of BIM management in any AEC organisation.

Crack detection at an early stage can prevent catastrophic structural failures. In this thesis, the inverse problem of crack detection in frames is studied. The direct problem of calculating the natural frequencies of beams and frames with multiple cracks is first tackled. A new method for natural frequency calculation is devised. The cracks are modelled as rotational springs. 4 × 4 dynamic stiffness matrices for beams are evaluated in a recursive manner, according to the number of cracks, by applying partial Gaussian eliminations. The resulting transcendental eigenvalue problem is solved using the Wittrick–Williams algorithm to extract the natural frequencies. Additional sign counts resulting from the partial Gaussian eliminations must be accounted for when applying the algorithm. The dynamic stiffness matrix of a frame with multiply cracked members is then assembled. The natural frequency calculation method forms a basis for detecting a single crack in a frame using only natural frequency measurements. Each frame member is discretised into a number of points. Selected natural frequencies are calculated accurately in the uncracked case and when the crack is placed individually at each discretisation point. The variation between the uncracked and cracked frequencies is normalised giving a number of curves corresponding to the selected frequencies. The normalisation is then applied on the measured frequencies. For noise free measurements, point crack locations are obtained. Applying the principles of interval arithmetic, noisy measurements give crack location ranges. Empirical probability distributions are used to graphically represent these ranges and their relative probabilities. Crack severity ranges are then obtained. The detection method is validated experimentally on a frame with scaled down dimensions. The fast Fourier transform is used to convert the time domain vibration signal into the frequency domain. Using higher order natural frequencies, two enhancement procedures for the detection method are devised and applied theoretically.

The alleviation of heating (in winter), cooling (in summer), artificial lighting and electricity use in office facilities is defined as a bioclimatic trend that offers sustainable building practice through a semi-transparent building integrated photovoltaic thermal envelope as a photovoltaic airflow window system. This thesis aims to produce synthesised design and strategies for the use of a proposed airflow window unit in office building in any given location and to maximise use of the renewable energy. Computational Fluid Dynamics (CFD), namely ANSYS Fluent 14.0, and ECOTECT have been employed to model the mechanical and natural ventilation of an office building integrated with a semi-transparent photovoltaic airflow window and the daylighting impact of various PV transparent degrees (15, 20, 25, 30 and 35 per cent) on the interior space, respectively, for winter and summer conditions. The use of such software has urged to establish a validation analysis a priori in order to ascertain the applicability of the tools to the targeted examination. The validation process involved a comparison of the results of CFD turbulence models, first, against benchmark and, second, against results of literature for identical component. The results of ECOTECT, in terms of daylight factor and illuminance level, were also compared against the results of Daysim/radiance, Troplux and BC/LC found in the literature. Excellent agreement was attained from the comparison of the results with errors less than 10 per cent. The study presents results of modelling of the airflow window system integrated into an office room for energy efficiency and adequate level of thermal and visual comfort. Results have revealed that the combination of mechanical and buoyancy induced flow spreads the heat internally warming the space to be thermally acceptable during the heating season whilst the mechanical convection is a main force for the cooling season. The thermal and visual comfort was compared for different PV airflow window transparent levels to determine the optimum PV transparency for the office space. Moreover, time-dependant and steady state conditions were imposed to predict the thermal and air behaviour for more elaborate investigation. The transient analysis was carried out, in sequential and individual base, according to the solar irradiance of each minute of working period, 8am-4pm (winter) and 5am-7pm (summer). The results obtained from transient and steady state, for both seasons, were compared and revealed negligible impact of transient effect. The PV electricity output was calculated from each transparency level under each condition, summer and winter (transient and steady). The predicted flow patterns, temperature distribution and the daylight factors in the room have been used to determine the most appropriate opening locations, sizes and system specifications for maintaining a comfortable indoor environment. The simulation investigation show that, for the proposed window model, optimum thermal and visual performance can be achieved from the PV transparency level of 20 per cent, during the heating season, and from the PV transmittance of 15 per cent, during the cooling season, where the PV output is highest. However the PV transparencies of 25, 30 and 35% can be reliable under altered conditions of operation.

Thesis advisor: Dawei Chen / We study the classes of several loci in the projectivization of the k-th Hodge bundle over the moduli space of genus g curves and over the moduli space of genus g curves with n marked points. In particular we consider the class of the closure in the projectivization of the k-th Hodge bundle over the moduli space of genus g curves with n marked points of the codimension n locus where the n marked points are zeros of the k-differential. We compute this class when n=2 and provide a recursive formula for it when n>2. Moreover, when n=1 and k=1,2 we show its rigidity and extremality in the pseudoeffective cone. We also compute the classes of the closures in the projectivization of the k-th Hodge bundle over the moduli space of genus g curves of the loci where the k-differential has a zero at a Brill-Noether special point. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Mathematics.

Double Skin Facades (DSFs) have been developed as an alternative technology to improve the thermal performance of conventional fully glazed buildings. Nevertheless, there is little test information on the behaviour and real performance of DSFs. This is specifically the case when the facade has to perform under extreme or moderate summer conditions. The characteristics of thermal overheating of a specific type of DSF with various configurations and its practical control have not been subjected to systematic experimental and computational investigations. This research which is based on an existent load of knowledge, carried out experiments of a full-scale one-storey laboratory chamber of a selected type of Double Skin Facade in which a comparative analysis of the thermal performance is assessed, CFD simulations of the experimental model and a Field Case Study of an existing building in the United Kingdom is also monitored. The basic thermal behaviour in the facade cavity and adjacent room is investigated by a series of parametric studies and basic flow field investigations. Section models of the DSF chamber and the case building were made and modelled using CFD in order to visualise the thermal and airflow behaviour inside the DSF complementing the experimental and field work. The modelling work has demonstrated the feasibility and versatility of the technique for probing the flow and thermal behaviour of double skin facades. It was found that natural ventilation through the cavity by a series of controlled opening shafts on the upper and lower facade are effective means to reduce DSF overheating. It was also observed that the optical properties of cavity elements, cavity depth size, solar control and the basic operation of the facade are key issues to address in order to prevent overheating and additional heat loads from the facade.

This research addresses the problem of populating Building Information Model databases with information on building construction materials using a new classification method which uses multi-spectral laser scanning intensity and geometry data. Research in multi-spectral laser scanning will open up a new era in survey and mapping; the 3D surface spectral response sensitive to the transmitted wavelengths could be derived day or night in complex environments using a single sensor. At the start of this research a commercial multi-spectral sensor did not exist, but a few prototype level instruments had been developed; this work wished to get ahead of the hardware development and assess capability and develop applications from multi-spectral laser scanning. These applications could include high density topographic surveying, seamless shallow water bathymetry, environmental modelling, urban surface mapping, or vegetative classification. This was achieved by using from multiple terrestrial laser scanners, each with a different laser wavelength. The fused data provided a spectral and geometric signature of each material which was subsequently classified using a supervised neural network. The multi-spectral data was created by precise co-positioning of the scanner optical centres and sub-centimetre registration using common sphere targets. A common point cloud, with reflected laser intensity values for each laser wavelength, was created from the data. The three intensity values for each point were then used as input to the classifier; ratios of the actual intensities were used to reduce the effect of range and incidence angle differences. Analysis of five classes of data showed that they were not linearly separable; an artificial neural network classifier was the chosen classifier has been shown to separate this type of data. The classifier training dataset was manually created from a small section of the original scan; five classes of building materials were selected for training. The performance of the classification was tested against a reference point cloud of the complete scene. The classifier was able to distinguish the chosen test classes with a mean rate of 84.9% and maximum for individual classes of 100%. The classes with the highest classification rate were brick, gravel and pavement. The success rate was found to be affected by several factors, among these the most significant, inter-scan registration, limitation on available wavelengths and the number of classes of material chosen. Additionally, a method which included a measure of texture through variations in intensity was tested successfully. This research presents a new method of classifying materials using multi-spectral laser scanning, a novel method for registering dissimilar point clouds from different scanners and an insight into the part played by laser speckle interpretation of reflected intensity.