1,179 research outputs found

    Colin Humphris

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    "Colin Humphris 2 Sqdrn. RAAF. 1941 - 1942 Author of - 'Trapped on Timor' (as a result of bombing of Darwin Feb. 19, 1942)".Colin Humphris. 2 Squadron, Royal Australian Air Force 1941 - 1942. Author of - 'Trapped on Timor' (as a result of bombing of Darwin February 19, 1942)

    Orbit design for future SpaceChip swarm missions in a planetary atmosphere

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    The effect of solar radiation pressure and atmospheric drag on the orbital dynamics of satellites-on-a-chip (SpaceChips) is exploited to design equatorial long-lived orbits about the oblate Earth. The orbit energy gain due to asymmetric solar radiation pressure, considering the Earth's shadow, is used to balance the energy loss due to atmospheric drag. Future missions for a swarm of SpaceChips are proposed, where a number of small devices are released from a conventional spacecraft to perform spatially distributed measurements of the conditions in the ionosphere and exosphere. It is shown that the orbit lifetime can be extended and indeed selected through solar radiation pressure and the end-of-life re-entry of the swarm can be ensured, by exploiting atmospheric drag

    Enumeration of Stack-Sorting Preimages via a Decomposition Lemma

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    We give three applications of a recently-proven "Decomposition Lemma," which allows one to count preimages of certain sets of permutations under West's stack-sorting map ss. We first enumerate the permutation class s1(Av(231,321))=Av(2341,3241,45231)s^{-1}(\text{Av}(231,321))=\text{Av}(2341,3241,45231), finding a new example of an unbalanced Wilf equivalence. This result is equivalent to the enumeration of permutations sortable by Bs{\bf B}\circ s, where B{\bf B} is the bubble sort map. We then prove that the sets s1(Av(231,312))s^{-1}(\text{Av}(231,312)), s1(Av(132,231))=Av(2341,1342,3241,3142)s^{-1}(\text{Av}(132,231))=\text{Av}(2341,1342,\underline{32}41,\underline{31}42), and s1(Av(132,312))=Av(1342,3142,3412,3421)s^{-1}(\text{Av}(132,312))=\text{Av}(1342,3142,3412,34\underline{21}) are counted by the so-called "Boolean-Catalan numbers," settling a conjecture of the current author and another conjecture of Hossain. This completes the enumerations of all sets of the form s1(Av(τ(1),,τ(r)))s^{-1}(\text{Av}(\tau^{(1)},\ldots,\tau^{(r)})) for {τ(1),,τ(r)}S3\{\tau^{(1)},\ldots,\tau^{(r)}\}\subseteq S_3 with the exception of the set {321}\{321\}. We also find an explicit formula for s1(Avn,k(231,312,321))|s^{-1}(\text{Av}_{n,k}(231,312,321))|, where Avn,k(231,312,321)\text{Av}_{n,k}(231,312,321) is the set of permutations in Avn(231,312,321)\text{Av}_n(231,312,321) with kk descents. This allows us to prove a conjectured identity involving Catalan numbers and order ideals in Young's lattice

    Reverse engineering of 3D-BIM of existing infrastructure using parametric tooling to accelerate the digitization transition in asset management: A research & development study by Colin Reit

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    Amid global climate change challenges, the construction industry faces an urgent  transition from a linear production model to a Circular Economy (CE). Initiatives  and recommendations in Dutch transition roadmaps and literature predominantly  focus on ensuring a future circular built environment, while lacking concrete actions on leveraging the existing assets for reuse. Dutch CE roadmap timelines  and interventions are developed based on Material Flow Analysis (MFA) studies with highly uncertain data input, this uncertainty impacts either environment or  economy with inaccurate interventions on the CE-transition. Secondly, the Replacement & Renovation (R&R) task of civil structures poses a threat for the  industry due to the limitations of capital, contractor capacity, and material  resources required to facilitate this peak. There is currently a lack of centrally  stored high-quality physical asset data available at public organisations. This data is essential in effectively managing the decommissioning peak and reduces risk for reuse realization. Lastly, Asset Management (AM) is transitioning towards a 3D-centralised strategy in line with Building Information Modelling (BIM) and  digital twins, while existing assets are still in 2D with often incomplete and  fragmented data documentation. Consequently, a large data quality gap is forming between new and existing assets. This led to the research question: How can centrally stored, quantified, and visualised asset data of existing infrastructure impact the CE-transition, bridge R&R-task efficiency, and AM practices? An upgrade towards 3D-BIM is required for existing assets to bridge this data gap. In doing so, facilitate higher quality- and more accessible asset specific  information that can be used in reusability scanning and structural assessments,  material quantification for CE-transition roadmap accuracy, and numerous AM  benefits. The costs for upgrading the existing assets using manual modelling or  3D scanning technology are currently too large to justify. An opportunity was  identified for modelling 3D-BIM of existing beam & slab bridges from 2D drawings using a modular approach to Parametric Engineering, aiming to reduce the investment threshold, and accelerating the digitization transition. Preliminary testing executed by the author showed a potential for 50-80% reduction in modelling efforts compared to conventional modelling practices with a volume  accuracy of >97%. The prototype calls for further development, validation, and similar efforts for other infrastructure types. The tool also showed potential for 3D structural & reusability assessments, reinforcement approx., and ptioneering & circularity scoring for the design phase. To put the tool’s use in perspective, a roadmap towards 3D centralized AM and a reuse economy was developed for AM. Civil Engineering | Construction Management and Engineerin

    Longitudinal train dynamics and vehicle stability in train operations

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    Cole, CR ORCiD: 0000-0001-8840-7136This chapter has been designed to provide a hands-on guide to both understanding and analysing longitudinal train dynamics. It is specifically focussed on the longitudinal dynamics of heavy-haul trains and adds new insights to previous work by the author [1–4], along with recent modelling work relevant to passenger trains [5]. It is 12 years since the first edition and the draft gear section is now expanded. New to the chapter is material concerning lateral wagon stability in the presence of lateral coupler force components. Passenger comfort and crashworthiness sections are also updated

    Oregon statewide status and trends report

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    Report -- Appendix A. Black Rock Desert-Humboldt -- Appendix B. Columbia River -- Appendix C. Deschutes -- Appendix D. Goose Lake -- Appendix E. Grande Ronde -- Appendix F. John Day -- Appendix G. Klamath -- Appendix H. Malheur -- Appendix I. Mid Coast -- Appendix J. Middle-Columbia-Hood -- Appendix K. North Coast-Lower Columbia -- Appendix L. Oregon Closed Basins -- Appendix M. Owyhee -- Appendix N. Powder-Burnt -- Appendix O. Rogue -- Appendix P. Sandy -- Appendix Q. Snake River -- Appendix R. South Coast -- Appendix S. Umatilla-Walla Walla-Willow -- Appendix T. Umpqua -- Appendix U. Willamette.prepared by: Colin Donald and Ryan Michie.Title from PDF cover (viewed on November 4, 2022).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references.Mode of access: Internet from the Oregon Government Publications Collection.Text in English

    Oregon statewide status and trends report

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    Chapter 1-3. Introduction and Methods -- Chapter 4-5. Results and Citations -- Appendix A. Black Rock Desert-Humboldt -- Appendix B. Columbia River -- Appendix C. Deschutes -- Appendix D. Goose Lake -- Appendix E. Grande Ronde -- Appendix F. John Day -- Appendix G. Klamath -- Appendix H. Malheur -- Appendix I. Mid Coast -- Appendix J. Middle-Columbia-Hood -- Appendix K. North Coast-Lower Columbia -- Appendix L. Oregon Closed Basins -- Appendix M. Owyhee -- Appendix N. Powder-Burnt -- Appendix O. Rogue -- Appendix P. Sandy -- Appendix Q. Snake River -- Appendix R. South Coast -- Appendix S. Umatilla-Walla Walla-Willow -- Appendix T. Umpqua -- Appendix U. Willamette.prepared by: Colin Donald, Yuan Grund, and Ryan Michie.Title from PDF cover (viewed on October 27, 2020).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references.Mode of access: Internet from the Oregon Government Publications Collection.Text in English

    Oregon statewide status and trends report

    No full text
    Report -- Appendix A. Black Rock Desert-Humboldt -- Appendix B. Columbia River -- Appendix C. Deschutes -- Appendix D. Goose Lake -- Appendix E. Grande Ronde -- Appendix F. John Day -- Appendix G. Klamath -- Appendix H. Malheur -- Appendix I. Mid Coast -- Appendix J. Middle-Columbia-Hood -- Appendix K. North Coast-Lower Columbia -- Appendix L. Oregon Closed Basins -- Appendix M. Black Owyhee -- Appendix N. Powder-Burnt -- Appendix O. Rogue -- Appendix P. Sandy -- Appendix Q. Snake River -- Appendix R. South Coast -- Appendix S. Umatilla-Walla Walla-Willow -- Appendix T. Umpqua -- Appendix U. Willamette.prepared by: Colin Donald, Ryan Michie, and Yuan Grund.Title from PDF cover (viewed on March 20, 2020).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references.Mode of access: Internet from the Oregon Government Publications Collection.Text in English

    The productivity effects of decentralized reforms - an analysis of the Chinese industrial reforms

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    The empirical literature on the effects of ownership has not distinguished between the effects of ownership and the effects of control. It has also generally ignored the dynamic effects of various ownership and control rights. Using a rich set of panel data about changes in China's state-owned enterprises, the author examines the static and dynamic effects of decentralizing ownership and control rights. He finds that productivity and growth rates improved significantly when reform improved the incentives for managers and employees to learn and to work hard - for example by decentralizing the rights to control wages, make production decisions, and appoint new managers. Increasing profit-retention rates and adopting performance contracts - conventionally viewed as the most important reforms for China's state enterprises - did not improve productivity much. Overall, decentralization accounted for a least 42 percent of productivity growth in Chinese state enterprises in the 1980s. Much of that gain came from improvements in the growth rate of productivity rather than in improved levels of productivity.Labor Policies,Economic Theory&Research,Environmental Economics&Policies,Banks&Banking Reform,Public Health Promotion,Economic Theory&Research,Environmental Economics&Policies,Banks&Banking Reform,Health Monitoring&Evaluation,Municipal Financial Management
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