275 resultados para Tall buildings Design and construction
Resumo:
Highway construction projects have direct impacts on adjacent businesses. The nature and the degree of impact depend on individual business characterization and project specific factors. The type of business is also a relevant factor in predicting the impact of transportation construction projects. This paper presents the results of research focused on developing an in-depth understanding of these relationships. The study includes project case studies of three transportation construction projects in Florida. Surveys were conducted with all adjacent businesses, which were combined with analyses of the business accommodation procedures employed by State Highway Agencies (SHAs) nationwide to provide measure the efficiency of present rules. The results include an analysis of differing priorities for different classification of businesses and development of design and construction management best practices to better accommodate businesses during highway construction. A pilot project that employed business accommodation principles devised in this research, and improvements to business accommodations observed were compared to cases where no measures were taken.
Resumo:
These lecture notes highlight some of the recent applications of multi-objective and multidisciplinary design optimisation in aeronautical design using the framework and methodology described in References 8, 23, 24 and in Part 1 and 2 of the notes. A summary of the methodology is described and the treatment of uncertainties in flight conditions parameters by the HAPEAs software and game strategies is introduced. Several test cases dealing with detailed design and computed with the software are presented and results discussed in section 4 of these notes.
Resumo:
This paper conceptualizes a framework for bridging the BIM-Specifications divide by embedding project-specific information in BIM objects by means of a product library. We demonstrate how model information, enriched with data at various levels of development (LODs), can evolve simultaneously with design and construction using a window object embedded in a wall as life-cycle phase exemplars at different levels of granularity. The conceptual approach is informed by the need for exploring an approach that takes cognizance of the limitations of current modelling tools in enhancing the information content of BIM models. Therefore, this work attempts to answer the question, “How can the modelling of building information be enhanced throughout the life-cycle phases of buildings utilizing building specification information?”
Resumo:
To date, designed topologies for DC-AC inversion with both voltage-buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viable buck-boost three-level inverters that can also support bidirectional power conversion. The proposed front-end circuitry is developed from the Cuk-derived buck-boost two-level inverter, and by using the "alternative phase opposition disposition" (APOD) modulation scheme, the buck-boost three-level inverters can perform distinct five-level line voltage and three-level phase voltage switching by simply controlling the active switches located in the designed voltage boost section of the circuits. As a cost saving option, one active switch can further be removed from the voltage-boost section of the circuits by simply re-routing the gating commands of the remaining switches without influencing the ac output voltage amplitude. To verify the validity of the proposed inverters, Matlab/PLECS simulations were performed before a laboratory prototype was implemented for experimental testing.
Resumo:
To date, designed topologies for DC-AC inversion with both voltage buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viable buck-boost three-level inverters that can also support bidirectional power conversion. The proposed front-end circuitry is developed from the Cuk-derived buck-boost two-level inverter, and by using the ldquoalternative phase opposition dispositionrdquo modulation scheme, the buck-boost three-level inverters can perform distinct five-level line voltage and three-level phase voltage switching by simply controlling the active switches located in the designed voltage boost section of the circuits. As a cost saving option, one active switch can further be removed from the voltage boost section of the circuits by simply rerouting the gating commands of the remaining switches without influencing the AC output voltage amplitude. To verify the validity of the proposed inverters, MATLAB/PLECS simulations were performed before a laboratory prototype was implemented for experimental testing.
Resumo:
The productivity of the construction industry has a significant effect on national economic growth. Gains from higher construction productivity flow through the economy, as all industries rely on construction to some extent as part of their business investment. Contractions and expansions of economic activity are common phenomena in an economy. Three construction cycles occurred between the years 1970 and 2011 in Malaysia. The relationships between construction productivity and economic development are examined by the partial correlation method to establish the underlying factors driving the change in construction productivity. Construction productivity is statistically significantly correlated with gross domestic product (GDP) per capita in a positive direction for the 1985–98 and 1998–2009 cycles, but not the 1970–85 cycle. Fluctuations in construction activities and the influx of foreign workers underlie the changes of construction productivity in the 1985–98 cycle. There was less fluctuation in construction activities in the 1998–2009 cycle, with changes being mainly due to the fiscal stimulation policies of the government in attempting to stabilize the economy. The intensive construction of mega-projects resulted in resource constraints and cost pressures during the 1980s and 1990s. A better management of the ‘boom-bust’ nature of the construction business cycle is required to maintain the capability and capacity of the industry.
Resumo:
Taking into consideration of growing energy needs and concern for environmental degradation, clean and inexhaustible energy source, such as solar energy, is receiving greater attention for various applications. The use of solar energy system reduces pollution, waste and has little or no harmful effects on the environment. It is appreciated that this source of energy can be complementary rather than being competitive to conventional energy sources. In order to collect and harness energy from the sun, a solar collector is essential. A solar collector is basically a heat exchanger that transforms solar radiant energy into heat or thermal energy. Improvement of performance is essential for commercial acceptance of their use in such applications. Many studies have been undertaken on the enhancement of thermal performance of solar collectors, using diverse materials of various shapes, dimensions and layouts. In the literature, various collector designs have been proposed and tested with the objective of meeting these requirements [1-8]. Omer et al. [1] found the efficiency of a solar collector of about 70% in a solar assisted heat pump system. Traditional solar collectors are single phase collectors, in which the working fluid is either air or water. Different modifications are suggested and applied to improve the heat transfer between the absorber and working fluid in a collector. These modifications include the use of absorber with fins attached [2,3], corrugated absorber [4,5], matrix type absorber [6], V-groove solar air collector [7]. Karim et al. [8] approached a review of design and construction of three types (flat, vee-grooved, and finned) of air collectors. Two-phase collectors, on the other hand, have significant potential for continuous operation round the clock, when used in conjunction with a compressor, as found in a solar assisted heat-pump cycle.
Resumo:
In this study we report the molecular design, synthesis, characterization, and photovoltaic properties of a series of diketopyrrolopyrrole (DPP) and dithienothiophene (DTT) based donor-acceptor random copolymers. The six random copolymers are obtained via Stille coupling polymerization using various concentration ratios of donor to acceptor in the conjugated backbone. Bis(trimethylstannyl)thiophene was used as the bridge block to link randomly with the two comonomers 5-(bromothien-2-yl)-2,5-dialkylpyrrolo[3,4-c]pyrrole-1, 4-dione and 2,6-dibromo-3,5-dipentadecyl-dithieno[3,2-b;2′,3′-d] thiophene. The optical properties of these copolymers clearly reveal a change in the absorption band through optimization of the donor-acceptor ratio in the backbone. Additionally, the solution processability of the copolymers is modified through the attachment of different bulky alkyl chains to the lactam N-atoms of the DPP moiety. Applications of the polymers as light-harvesting and electron-donating materials in solar cells, in conjunction with PCBM as acceptor, show power conversion efficiencies (PCEs) of up to 5.02%.
Resumo:
Curriculum scholars and teachers working for social justice and equity have been caught up in acrimonious and polarizing debates over content, ideology and disciplinary knowledge. At the forefront in cutting through these debates and addressing the practical questions involved, this book is distinctive in looking to the technical form of the curriculum rather than its content for solutions. The editors and contributors, all leading international scholars, advance a unified, principled approach to the design of syllabus documents that aims for high quality/high equity educational outcomes and enhances teacher professionalism.
Resumo:
Describes the development and testing of a robotic system for charging blast holes in underground mining. The automation system supports four main tactical functions: detection of blast holes; teleoperated arm pose control; automatic arm pose control; and human-in-the-loop visual servoing. We present the system architecture, and analyse the major components, Hole detection is crucial for automating the process, and we discuss theoretical and practical aspects in detail. The sensors used are laser range finders and cameras installed in the end effector. For automatic insertion, we consider image processing techniques to support visual servoing the tool to the hole. We also discuss issues surrounding the control of heavy-duty mining manipulators, in particular, friction, stiction, and actuator saturation.
Resumo:
Annually, several million tonnes of waste are produced from reworks, demolition, and use of substandard materials. Building Information Modelling (BIM), a digital representation of facilities and their constituent data, is a viable means of addressing some concerns about the impacts of these processes. BIM functionalities can be extended and combined with rich building information from specifications and product libraries, for efficient, streamlined design and construction. This paper conceptualises a framework for BIM-knowledge transfer from advanced economies for adaptation and use in urban development works in developing nations using the Sydney Down Under and Lagos Eko Atlantic projects as reference points. We present a scenario that highlights BIM-based lifecycle planning/specifications as agents of sustainable construction (in terms of cost and time) crucial to the quality of as-built data from early on in city development. We show how, through the use of BIM, city planners in developing nations can avoid high, retrospective (and sometimes wasteful) maintenance costs and leapfrog infrastructure management standards of advanced economies. Finally, this paper illustrates how BIM can address concerns about economic sustainability during city development in developing countries by enriching model objects with specification information sourced from a product library.
Resumo:
Driven by information accessibility-on-demand provided by the internet, education modes are changing from a teacher-led approach focused on content delivery and assessible outcomes, to a learner-based approach encouraging self-directed, peer-tutored, and cooperative learning. New pedagogies are required to extend learning beyond the classroom and traditional subject areas such as contemporary arts, in alignment with the cross disciplinary priorities of the Australian Curriculum and values of the International Baccalaureate Organisation. This research explores how partnerships with universities and cultural organisations are implicated in the generation of these new forms of pedagogy and contribute to the field of educational research within the context of Education Queensland’s Framework For Gifted Education. In particular, this paper explores a new pedagogical framework for highly capable year five to nine Queensland state school students at the intersection of arts, design and the sciences, which has arisen from an explicit secondary/ tertiary partnership between the Queensland University of Technology Creative Industries Faculty and Precincts and the Queensland Academies Young Scholars Program. The Young Scholars Program offers experiences in the International Baccalaureate and Australian Curriculum contexts to enhance outcomes via global understanding, unique industry partnerships and 21st century pedagogical innovation based not on 'content' but tacit/experiential learning concepts including immersive, creative, intellectual and social strategies. These strategies for highly capable students are centred around authentic opportunities, primary resources, transdisciplinary learning and relationships with likeminded peers including tertiary arts, design and STEM educators and students, professionals and researchers. The presentation details case studies which are hands-on real time workshops involving inquiry based challenges in the arts, design and sciences, mathematics, history, creative writing and other disciplines, with content drawn from collections from public institutions, academic research and tertiary pedagogy. Both programs implicate student collaboration and creative production as methodology/data capture for ongoing action research, in alignment with the Framework For Gifted Education’s emphasis on evidence-based practices. They also challenge gifted students “to continue their development through curricular activities that require depth of study, complexity of thinking, fast pace of learning, high-level skills development and/or creative and critical thinking (e.g. through independent investigations, tiered tasks, diverse real-world applications, mentors)”(Education Queensland, 2011:3). This presentation highlights the strengths of the ongoing collaboration between QUT Creative industries Faculty and Queensland Academies, which not only provides successful extra curricular activities for gifted students towards a place in the International Baccalaureate Program, but also provides mentoring opportunities for tertiary students in their field of endeavor to assist with their own learning, and unique research opportunities for the Faculty as it focuses on excellence in arts, design and creative education and research. Education Queensland.(2011). Framework For Gifted Education Revised Edition 2011 (accessed Nov 19 2011)
Resumo:
Purpose Two diodes which do not require correction factors for small field relative output measurements are designed and validated using experimental methodology. This was achieved by adding an air layer above the active volume of the diode detectors, which canceled out the increase in response of the diodes in small fields relative to standard field sizes. Methods Due to the increased density of silicon and other components within a diode, additional electrons are created. In very small fields, a very small air gap acts as an effective filter of electrons with a high angle of incidence. The aim was to design a diode that balanced these perturbations to give a response similar to a water-only geometry. Three thicknesses of air were placed at the proximal end of a PTW 60017 electron diode (PTWe) using an adjustable “air cap”. A set of output ratios (ORfclin Det ) for square field sizes of side length down to 5 mm was measured using each air thickness and compared to ORfclin Det measured using an IBA stereotactic field diode (SFD). k fclin, f msr Qclin,Qmsr was transferred from the SFD to the PTWe diode and plotted as a function of air gap thickness for each field size. This enabled the optimal air gap thickness to be obtained by observing which thickness of air was required such that k fclin, f msr Qclin,Qmsr was equal to 1.00 at all field sizes. A similar procedure was used to find the optimal air thickness required to make a modified Sun Nuclear EDGE detector (EDGEe) which s “correction-free” in small field relative dosimetry. In addition, the feasibility of experimentally transferring k fclin, f msr Qclin,Qmsr values from the SFD to unknown diodes was tested by comparing the experimentally transferred k fclin, f msr Qclin,Qmsr values for unmodified PTWe and EDGEe diodes to Monte Carlo simulated values. Results 1.0 mm of air was required to make the PTWe diode correction-free. This modified diode (PTWeair) produced output factors equivalent to those in water at all field sizes (5–50 mm). The optimal air thickness required for the EDGEe diode was found to be 0.6 mm. The modified diode (EDGEeair) produced output factors equivalent to those in water, except at field sizes of 8 and 10 mm where it measured approximately 2% greater than the relative dose to water. The experimentally calculated k fclin, f msr Qclin,Qmsr for both the PTWe and the EDGEe diodes (without air) matched Monte Carlo simulated results, thus proving that it is feasible to transfer k fclin, f msr Qclin,Qmsr from one commercially available detector to another using experimental methods and the recommended experimental setup. Conclusions It is possible to create a diode which does not require corrections for small field output factor measurements. This has been performed and verified experimentally. The ability of a detector to be “correction-free” depends strongly on its design and composition. A nonwater-equivalent detector can only be “correction-free” if competing perturbations of the beam cancel out at all field sizes. This should not be confused with true water equivalency of a detector.