771 research outputs found

    Analysis and Design of Wood Construction Platforms Using Instrumentation

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    Wood construction platforms are a common method for inexpensive, temporary soil stabilization under heavy machinery; however, platforms are not typically thought of as an engineered product. Review of literature has shown that only one design method is currently available and is specific to one type of platform configuration. The purpose of this thesis is to develop a design method that is simple, versatile and accurate. The proposed design method was intentionally developed so that the designer would have input in multiple areas of the design. Instrumentation allowed for increased insight into the mechanical behavior of the platforms. The objective of this research is to use measured strain, load, and deflection in conjunction with fundamental engineering mechanics principles to predict a single platform’s mechanical behavior on the ground. Results from this method compare favorably with the only other design guide available and improves the knowledge base by developing design guidance for any type of wood construction platform

    Analysis and Design of Wood Construction Platforms Using Instrumentation

    Get PDF
    Wood construction platforms are a common method for inexpensive, temporary soil stabilization under heavy machinery; however, platforms are not typically thought of as an engineered product. Review of literature has shown that only one design method is currently available and is specific to one type of platform configuration. The purpose of this thesis is to develop a design method that is simple, versatile and accurate. The proposed design method was intentionally developed so that the designer would have input in multiple areas of the design. Instrumentation allowed for increased insight into the mechanical behavior of the platforms. The objective of this research is to use measured strain, load, and deflection in conjunction with fundamental engineering mechanics principles to predict a single platform’s mechanical behavior on the ground. Results from this method compare favorably with the only other design guide available and improves the knowledge base by developing design guidance for any type of wood construction platform

    The application of advanced finite element analysis for structural fire design

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    This paper presents a case study into the use of advanced finite element analysis as part of a performance based structural fire engineering design for a multi-storey steel framed building in New Zealand. The building is a multi-storey steel framed building with long span cellular beams supporting composite concrete floor slabs. As part of the building design, the secondary steel beams and composite columns of the structure are proposed to be unprotected. A series of advanced finite element analysis using the SAFIR finite element programis carried out to test the robustness of structure without passive fire protection for the secondary beams and composite columns. The numerical modelling features thermal modelling of the structural elements and 3D structural modelling of the heated elements to test the behaviour of the long span beams under realistic compartment fires. The analysis utilizes non-linear temperature dependent materials to consider realistic behaviour of the structural response under a fully developed compartment fire, including the rapid thermal loading during flashover and the cooling phase of the fire. The analysis is able to consider the different realistic structural responses during the course of the fire including contraction during the cooling phase and lateral buckling of the cellular beams in fire. This paper shows how such an analysis can be applied by consulting engineers on a realistic building design to demonstrate a robust design for a steel framed building with unprotected structural elements whilst providing savings with reduced amount of fire protection to the structure

    Timing and Nature of Post-Collapse Sedimentation in Kulshan Caldera, North Cascades, Washington

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    Sedimentary rocks found in the 4.5 x 8 km Kulshan caldera of the Mount Baker volcanic field in the North Cascades, WA, indicate that the post-collapse basin hosted a lacustrine environment shortly after the initial collapse at 1.149 Ma (Hildreth, 1996). The sedimentary rocks of the 14 Goat area in Kulshan caldera are well-preserved in 124 meters of stratigraphic exposure. Blocks of wall rock debris in the lower stratigraphy show instability in the caldera wall. Intermediate and late stages are mainly turbidites composed primarily of sediments derived from extra-caldera ignimbrite. From these 1 interpret the 14 Goat area of Kulshan to have been a steep and deep depositional basin for most of its history. Additional sedimentary structures found in Kulshan caldera reveal a complex environmental history. Trough cross-bedding within a well sorted sandstone indicates channelized flow. Clastic dikes resulted from the overburdening of wet sediments. Dropstones found throughout the stratigraphy indicate an active ice field. Outside the stratigraphic section but within the 14 Goat area oscillation ripples indicate shallow water and raindrop imprints show drying. Paleomagnetic analysis of 12 sites spanning the entire stratigraphic column failed to show that any magnetic transition was recorded in the Kulshan sediments. Anisotropy of magnetic susceptibility results confirm that grain settling from quiet water produced the most prominent magnetic fabric and confirm secondary alteration was likely the cause of scatter in the remanent magnetization signal. A conservative estimate for the duration of the lacustrine environment at Kulshan caldera is 157 ka leading to a minimum rate of sedimentation of 79 cm/ka. A shorter estimate suggests duration of 22 ka and rate of sedimentation of 560 cm/ka. The sedimentary environments of Kulshan caldera are similar to other calderas with post-collapse depositional records. Kulshan caldera compares favorably to depositional models for small calderas (less than 10 km)

    Multi-rate relaying for performance improvement in IEEE 802.11 WLANs

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    It is well known that the presence of nodes using a low data transmit rate has a disproportionate impact on the performance of an IEEE 802.11 WLAN. ORP is an opportunistic relay protocol that allows nodes to increase their effective transmit rate by replacing a low data rate transmission with a two-hop sequence of shorter range, higher data rate transmissions, using an intermediate node as a relay. ORP differs from existing protocols in discovering relays experimentally, by optimistically making frames available for relaying. Relays identify themselves as suitable relays by forwarding these frames. This approach has several advantages compared with previously proposed relay protocols: Most importantly, ORP does not rely on observations of received signal strength to infer the availability of relay nodes and transmit rates. We present analytic and simulation results showing that ORP improves the throughput by up to 40% in a saturated IEEE 802.11b network

    Position practices of the present-day CFO: a reflection on historic roles at Guinness, 1920-1945

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    AbstractContemporary studies of Chief Financial Officers (CFO) paint a picture of the role pre-1960 as being reflective of a more transactional one. Historical research sheds some doubt on this, and tends not to separate the role from its occupier. We provide an analysis of such a role in a large brewery from about 1920 to 1945. Drawing on the concept of position-practices, our results suggest that a CFO-predecessor role was informed by existing position-practices, which are separately identifiable from the occupier of the role itself. Some of the position-practices are recognizable in contemporary CFO roles. Importantly, focusing on the role as opposed to the occupier, gives our study potential to more broadly inform future research on the contemporary role

    Green space, blue space and mental health in an urban setting: A phenomenological study

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    Objective: Exposure to green space is correlated with positive mental health outcomes; however, there is a lack of qualitative studies focusing on experiences of this phenomenon. Therefore, the research objective was to examine individual’s experiences of mental restoration after spending time in urban parks. Methods: A phenomenological approach was used. Fifteen participants in Lethbridge, Alberta, were interviewed, all of whom used parks and believed it benefitted their mental health. Results: Analysis revealed four main themes highlighted by participants, including connections to nature, connections to community, connections to themselves, and built environment features. These themes may be important aspects of the experience of mental restoration and may factor in the relationship between green space and mental health. Conclusion: The results support ongoing development of a variety of urban green spaces. Further, they suggest the need for more research into the complex relationship between green space and mental health and moderating factors

    Green space, blue space and health in an urban setting : a phenomenological study

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    Objective: Exposure to green space is correlated with positive mental health outcomes; however, there is a lack of qualitative studies focusing on experiences of this phenomenon. Therefore, the research objective was to examine individual’s experiences of mental restoration after spending time in urban parks. Methods: A phenomenological approach was used. Fifteen participants in Lethbridge, Alberta, were interviewed, all of whom used parks and believed it benefitted their mental health. Results: Analysis revealed four main themes highlighted by participants, including connections to nature, connections to community, connections to themselves, and built environment features. These themes may be important aspects of the experience of mental restoration and may factor in the relationship between green space and mental health. Conclusion: The results support ongoing development of a variety of urban green spaces. Further, they suggest the need for more research into the complex relationship between green space and mental health and moderating factors
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