The use of seawater in cooling towers for industrial applications has much merit in the Gulf Cooperation Council countries due to the scarcity and availability of fresh water. Seawater make-up in cooling towers is deemed the most feasible because of its unlimited supply in coastal areas. Such latent-heat removal with seawater in cooling towers is several folds more efficient than sensible heat extraction via heat exchangers. Operational challenges such as scaling, corrosion, and biofouling are a major challenge in conventional cooling towers, where the latter is also a major issue in seawater cooling towers. Biofouling can significantly hamper the efficiency of cooling towers. The most popular methods used in cooling treatment to control biofouling are disinfection by chlorination. However, the disadvantages of chlorination are formation of harmful disinfection byproducts in the presence of high organic loading and safety concerns in the storage of chlorine gas. In this study, the research focuses on biofouling control in seawater cooling towers by investigating two different approaches. The first strategy addresses the use of alternative oxidants (i.e. ozone micro-bubbles and chlorine dioxide) in treatment of cooling towers. The second strategy investigates removing nutrients in seawater using granular activated carbon filter column and ultrafiltration to prevent the growth of microorganisms. Laboratory bench-scale tests in terms of temperature, cycle of concentration, dosage, etc. indicated that, at lower oxidant dosages (total residual oxidant (TRO) equivalent = 0.1 mg/l Cl2), chlorine dioxide had a better disinfection effect than chlorine and ozone. The performance of oxidizing biocides at pilot scale, operating at assorted conditions, showed that for the disinfectants tested, ozone could remove 95 % bioactivity of total number of bacteria and algae followed by chlorine dioxide at 85%, while conventional chlorine dosing only gave 60% reduction in bioactivities. Test results of GAC bio-filter showed that around 70 % removal of total organic carbon in the seawater feed was achieved and was effective in keeping the microbial growth to a minimum. The measured results from this study enable designers of seawater cooling towers to manage the biofouling problems when such cooling towers are extrapolated to a pilot scale.

Wind energy has emerged as a promising and renewable solution to reduce reliance on fossil fuels in remote off-grid locations. Conventional wind turbine towers are made from concrete or steel, which present several significant drawbacks in certain applications. The use of lightweight and corrosion-resistant fibre reinforced polymer (FRP) tubes as permanent structural formwork can mitigate these challenges. Existing literature has highlighted the performance of concrete-filled FRP tubes (CFFTs) through experiments and successful applications in the field. However, only a few cantilever CFFTs have been tested, and their sizes were much smaller than required for wind turbine towers. In consequence, this thesis focuses on relatively large cantilever CFFTs at a scale representative of small wind turbine towers. The finite element (FE) method was adopted to simulate the behaviour of CFFT towers using the commercial software ABAQUS. The first part of this thesis presents the development and validation of CFFT FE models under bending and axial loading conditions, as well as hollow FRP tubes under bending. The models were compared to experimental results reported by Fam (2000) to ensure the selection of appropriate material properties. Good agreements were observed, and the accuracy of the FE modelling approach was proved. Subsequently, a parametric study was conducted to explore the feasibility of CFFTs for wind turbine towers. The analyses of cantilever towers with different geometric properties and reinforcement configurations under concentrated lateral load were performed first. Then, a cantilever CFFT tower under different loading configurations was tested. It is noted that towers subjected to concentrated load had the lowest load capacity and stiffness. Conclusions were made that with or without axial load, lateral load eccentricity does not affect the behaviour of cantilever CFFTs significantly. Meanwhile, the increase in height-to-diameter ratio decreases the load capacity and stiffness of cantilever CFFTs. Finally, the CFFT tower results were compared with concrete and steel tubular models with similar geometry. The results suggest that CFFTs have better overall performance than the other two types of towers. They are also superior with respect to flexibility in installation and their durability.

The tower crane is an electromechanical equipment that is used for the vertical transport of materials in a construction project and together with the two riggers form the work team to carry out this task. One of the main problems in the construction of multifamily buildings corresponds to the use of the tower crane because vertical transport causes non-contributory times, which is, dead times and waits above expectations. This research analyzes the current vertical transport process and proposes its optimization through some management tools with the aim of improving the productivity of the use of the tower crane by reducing non-contributory times. To this end, the productivity of the work team is recorded in several projects with similar characteristics, then the main problems are selected to analyze them and finally the process is optimized. The results determined that non-contributory times can be reduced by 10% if there is an orderly and continuous process.

Design of the territory and revitalization location

A drop tower is a device that produces a microgravity environment by allowing an experiment to free fall for a short period of time, usually less than 10 seconds. Certain types of drop towers are also capable of reproducing the gravitational conditions of other celestial bodies, such as Lunar and Martian gravity. Microgravity environments are often required for many different scientific experiments, such as experiments in material science, fluid dynamics, biological studies and many other fields. Microgravity environments are also often used as a specialized manufacturing method for certain materials. Components and systems that will be used in space or onboard sounding rockets can also be tested and verified using drop towers before launch. There is an ever-present need to conduct experiments in a microgravity environment and thus highlights the importance and relevance of drop towers in research and design verification. Other microgravity facilities such as sounding rockets, parabolic flights and orbital spacecraft typically provide longer microgravity durations, however, come at a considerable cost. This highlights the need for drop towers that are cost-effective as a desirable research device. This thesis consists of a comprehensive, systematic literature review to determine industry standards and the current state of the art in the world of drop towers. The different potential mechanical designs of a drop tower are then analyzed and trade-offs are completed. The most suitable design, that could feasibly be built at Luleå University of Technology (LTU)’s space campus, is chosen and presented later in this thesis. The safety of the drop tower was of utmost concern when deciding on the most suitable design as well as when completing the mechanical design of the drop tower. The slider is a major component of a drop tower, it houses the experiment and is a critical component in determining the achievable microgravity quality. The slider design was also analyzed with a trade-off analysis of the potential existing designs, with the most feasible design being chosen. The drop tower is planned to be installed in the LTU Spacecampus light garden which can accommodate a drop tower of approximately 13m in height. The mechanical design is verified using various Finite Element Analysis (FEA) simulations. The 14m planned and designed drop tower is a non-vacuum, guided design which would provide approximately 3 seconds of microgravity, 5.2 seconds of Martian simulated gravity and 7.8 seconds of Lunar simulated gravity. The drop tower has been designed to accommodate projects that are part of the REXUS program. The towers' considerable size and ease of use would make it suitable for many research institutions and many potential scientific studies.

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This lighthouse is a visual anchor from land and sea. Its three concrete towers reach 250 feet tall with a base diameter of 75 feet. Accompanying its rotating spotlight is a central spotlight, lighting the core of the tower vertically and continuing into the sky. Nested 150 feet up the tower is the residence for the lighthouse keeper. Siting at a high elevation along a shear cliff face, the often fog shrouded tower is a strong light signal for voyagers at sea. / Master of Architecture

Design in the civic realm demands opportunities to recognize commonality. Architecture, therefore, must provide a call and response between visitor and space. This intimate dialogue can only occur where landscape elements speak a universal language. Revelatory, Allegorical, Cosmological and Vernacular methods of design have traditionally been employed to communicate in the landscape. This project explores the method of Archetypal design as a means to avoid the culturally-dependent, and hence, esoteric language of design and so create an exoteric language more appropriate for civic space. / Master of Landscape Architecture

This thesis was a study of a structure that legitimized the senses and provoked emotion by creating different experiential conditions. / Master of Architecture

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