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Slope reliability and back analysis of failure with geotechnical parameters estimated using Bayesian inference

Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 628-643页

作者： Luis-Fernando Contreras Edwin T.brown The University of Queensland St Lucia Campus

A Bayesian approach is proposed for the inference of the geotechnical parameters used in slope *** methodology involves the construction of posterior probability distributions that combine prior information on the parameter values with typical data from laboratory tests and site investigations used in *** posterior distributions are often complex,multidimensional functions whose analysis requires the use of Markov chain Monte Carlo(MCMC)*** procedures are used to draw representative samples of the parameters investigated,providing information on their best estimate values,variability and *** paper describes the methodology to define the posterior distributions of the input parameters for slope design and the use of these results for evaluation of the reliability of a slope with the first order reliability method(FORM).The reliability analysis corresponds to a forward stability analysis of the slope where the factor of safety(FS)is calculated with a surrogate model from the more likely values of the input *** Bayesian model is also used to update the estimation of the input parameters based on the back analysis of slope *** this case,the condition FS?1 is treated as a data point that is compared with the model prediction of *** analysis requires a sufficient number of observations of failure to outbalance the effect of the initial input *** parameters are updated according to their uncertainty,which is determined by the amount of data supporting *** methodology is illustrated with an example of a rock slope characterised with a Hoek-brown rock mass *** example is used to highlight the advantages of using Bayesian methods for the slope reliability analysis and to show the effects of data support on the results of the updating process from back analysis of failure.

关键词： Bayesian analysis Hoek-brown criterion Slope reliability Back analysis of failure

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Cryogenic nanosecond and picosecond high average and peak power(HAPP) pump lasers for ultrafast applications

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High Power Laser Science and Engineering 2016年第2期4卷 37-67页

作者： David C.brown Sten Tornegrd Joseph Kolis Snake Creek Lasers LLC Clemson University Department of Chemistry

Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

关键词： cryogenic lasers high-average-power lasers high-peak-power lasers ultrafast lasers Yb lasers

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Rock engineering design of post-tensioned anchors for dams - A review

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第1期7卷 1-13页

作者： E.T. brown Golder Associates Ply Ltd. PO Box 1734 Milton Queensland 4064 Australia

High-capacity, post-tensioned anchors have found wide-spread use, originally in initial dam design and construction, and more recently in the strengthening and rehabilitation of concrete dams to meet modern design and safety standards. Despite the advances that have been made in rock mechanics and rock engineering during the last 80 years in which post-tensioned anchors have been used in dam en- gineering, some aspects of the rock engineering design of high-capacity rock anchors for dams have changed relatively little over the last 30 or 40 years. This applies, in particular, to the calculations usually carried out to establish the grouted embedment lengths required for deep, post-tensioned anchors. These calculations usually make simplified assumptions about the distribution and values of rock-grout interface shear strengths, the shape of the volume of rock likely to be involved in uplift failure under the influence of a system of post-tensioned anchors, and the mechanism of that failure. The resulting designs are generally conservative. It is concluded that these aspects of the rock engineering design of large, post- tensioned rock anchors for dams can be significantly improved by making greater use of modern, comprehensive, numerical analyses in conjunction with three-dimensional （3D） models of the rock mass structure, realistic rock and rock mass properties, and the results of prototype anchor tests in the rock mass concerned.

关键词： Dam engineering Post-tensioned anchorsRock engineering designGrout-tendon bondRock-grout bondRock mass uplift failure

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Barriers to Insurance as a Flood Risk Management Tool:Evidence from a Survey of Property Owners

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International Journal of Disaster Risk Science 2020年第3期11卷 263-273页

作者： Jason Thistlethwaite Daniel Henstra Craig brown Daniel Scott School of Environment Enterprise and DevelopmentUniversity of WaterlooWaterlooON N2L 3G1Canada Department of Political Science University of WaterlooWaterlooON N2L 3G1Canada Climate Change and Health Adaptation Planning Vancouver Coastal HealthVancouverBC V5Z 4C2Canada Department of Geography and Environmental Management University of WaterlooWaterlooON N2L 3G1Canada

By using risk-adjusted price signals to transfer responsibility for property-level flood protection and recovery from governments to property owners,flood insurance represents a key tenet of the flood risk management(FRM)*** Government of Canada has worked with insurers to introduce flood insurance for the first time as a part of a broader shift towards FRM to limit the growing costs of *** viability of flood insurance in Canada,however,has been questioned by research that disputes the utility of purchasing coverage by property *** study tested this assumption by drawing on public opinion survey data to assess factors that influence decisions about the utility of *** findings reveal that Canadians have limited knowledge of flood insurance coverage,exhibit a low willingness-to-pay for both insurance and property-level flood protection measures,and expect governments to shoulder much of the financial burden of flood recovery through disaster assistance.

关键词： Flood insurance Flood risk management Risk-sharing Willingness-to-pay

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Digital re-analysis of lost architecture and the particular case of Lutyens＇ Liverpool Metropolitan Cathedral

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Frontiers of Architectural Research 2016年第2期5卷 265-275页

作者： Nicholas Webb Andre brown School of Architecture University of Liverpool Liverpool L69 7ZN United Kingdom

Research and critique of unbuilt or destroyed works of architecture is traditionally carried out through the examination of surviving information such as drawings, models, photographs, biographies and monographs. The case study presented here demonstrates that this approach cannot always give a fuU-picture of the architect or designer＇s intentions, and may miss inconsistencies in the design and links to other precedents or antecedents in such schemes. Here, we employ strategic contemporary digital representation techniques to re-present and re-analyse the evidence available for a particular architectural project. We describe a systematic methodology, which shows that these techniques can challenge or enhance current understanding. The focus therefore is on the digital re-analysis process that has been devised. Sir Edwin Lutyens＇ unbuilt Liverpool Metropolitan Cathedral design, that would have delivered one of the largest cathedrals in the world, is used as a case study. The findings reveal new information about the cathedral by following structured lines of enquiry generated from the study of primary and secondary source data, as well as serendipitous results that occur as a potential by-product of the methodological process.

关键词： Unbuitt architecture Digitalcritique Forensic anatysis Digitat modetting

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Farmers’knowledge,attitudes,and practices with respect to rodent management in the upland and lowland farming systems of the Lao People’s Democratic Republic

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Integrative Zoology 2007年第3期2卷 165-173页

作者： Peter R.brown Khamouane KHAMPHOUKEO CSIRO Sustainable Ecosystems CanberraAustralian Capital TerritoryAustralia National Agricultural and Forestry Research Institute VientianeLao PDR

Rodents are a serious constraint to poor farmers in the upland and lowland farming systems of the Lao People’sDemocratic Republic and have been described as the pest they have least control over. To better understand theseproblems a baseline survey of farmers was conducted to assess their knowledge, attitudes, and practices with respectto rodent management. A structured survey was conducted in 12 villages across Luang Namtha, Luang Prabang,and Houaphan provinces. Twenty farmers from each village were interviewed (a total of 240 farmers). Farmersnoted that the main factor limiting production was pests (70%), with rats identified as the most important pest(98%). The mean yield loss was estimated at 19% (range 0–100%). Trapping and rodenticides were commonlyused by farmers. Farmers believed that it was important to control rats and believed that rats could only be controlledif farmers worked together. However, 65% of farmers conducted rodent control by themselves, and 92% offarmers believed that rodenticides were harmful to the environment. The main constraints identified were the highcost of some control methods and the need to get farmers to work together as a community.

关键词： decision making farmers’beliefs pest rice rodent management upland crop

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The effects of total ankle replacement on ankle joint mechanics during walking

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Journal of Sport and Health Science 2017年第3期6卷 340-345页

作者： Henry Wang Scott R.brown Biomechanics Laboratory School of KinesiologyBall State University Sports Performance Research Institute New Zealand(SPRINZ) Auckland University of Technology

Background:End-stage ankle arthritis impairs joint function and patients' *** ankle replacement is a surgical procedure to treat severe ankle *** Talaris Anatomic Ankle^(TM)(STAA) was designed to mimic the normal ankle anatomy and flexion/extension of the ankle *** purpose of this study was to examine the effect of an STAA ankle replacement on ankle joint function and mechanics during ***:Five patients with end-stage unilateral ankle arthritis were *** performed level walking in a laboratory setting on 2occasions,prior to and 3 months after the STAA ankle *** Orthopedic Foot and Ankle Society(AOFAS) hindfoot score was obtained.A 12-camera motion capture system was used to perform walking *** temporo-spatial parameters and ankle joint mechanics were *** Student's t tests and non-parametric Wilcoxon matched tests were performed to examine the differences in biomechanical variables between the pre-and post-surgery walking ***:Compared to the pre-surgical condition,at 3 months of post-STAA surgery,patients experienced greater improvement in AOFAS hindfoot score(p = 0.0001);the STAA ankle demonstrated a 31% increase in ankle joint excursion(p = 0.045),a 22% increase in ankle plantarflexor moment(p = 0.075),a 60% increase in ankle power absorption(p = 0.023),and a 68% increase in ankle power production(p = 0.039).Patients also demonstrated a 26% increase in walking speed(p = 0.005),a 20% increase in stride length(p = 0.013),a 15% decrease in double support time(p = 0.043),and a 5% decrease in total stance time(p = 0.055).Conclusion:Three months after surgeries,the STAA patients experienced improvements in ankle function and gait *** STAA ankle demonstrated improved ankle mechanics during daily activities such as walking.

关键词： Ankle mechanics AOFAS score Arthritis Gait analysis Total ankle replacement Walking

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Polyphenol composition and antioxidant potential of mint leaves

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Food Production, Processing and Nutrition 2019年第1期1卷 128-141页

作者： Nicole brown Jenny AJohn Fereidoon Shahidi Department of Biochemistry Memorial University of NewfoundlandSt.John’sNL A1B 3X9Canada Present Address:Department of Food Science and Technology Kerala University of Fisheries and Ocean StudiesKochiKerala 682506India

Soluble and insoluble/bound phenolic compounds and an aqueous infusion of two mint species(Medina and Hasawi),were tested for their total phenolic content,2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonate(ABTS)and 1,1-diphenyl-2picrylhydrazyl(DPPH)radical scavenging activity,iron(Ⅲ)reduction,iron(Ⅱ)chelating and oxygen radical absorbance capacity(ORAC).Furthermore,the potency of the mint extracts in the inhibition of radical-induced DNA scission,human low-density lipoprotein(LDL)cholesterol oxidation,formation of thiobarbituric acid reactive substances(TBARS)in a cooked ground meat system and LPS(lipopolysaccharide)-stimulated cyclooxygenase-2(COX-2)expression in J774A.1 mouse macrophage cells were *** showed that the soluble phenolics had a higher phenolic content and antioxidant activity than the insoluble-bound extracts and aqueous infusions in most of the *** varieties exhibited notable antioxidant activities and inhibition of LDL cholesterol oxidation,DNA scission and COX-2 gene expression at transcriptional ***,Medina mint was a more potent antioxidant than the Hasawi *** performance liquid chromatography with online tandem electrospray ionization mass spectrometry(HPLC/ESI-MS/MS)analysis of the extracts revealed that rosmarinic acid was the major phenolic compound present in both mint samples.

关键词： Mint Phenolic compounds Antioxidant activity Rosmarinic acid HPLC ESI-MS MS

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A rare complication of a common disease: Bouveret syndrome, a case report

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World Journal of Gastroenterology 2006年第16期12卷 2620-2621页

作者： Yazan Adnan Masannat Scott Caplin Tim brown Department of General Surgery Morriston HospitalSwanseaWalesSA6 6NLUnited Kingdom

This is a case report of an 85-year old patient who presented with abdominal pain, nausea and vomiting associated with altered liver function test. The plain X-rays and CT scan showed pneumobilia with an ectopic *** patient was diagnosed with Bouveret syndrome and managed surgically. The report is followed by a discussion about Bouveret syndrome.

关键词： Bouveret syndrome Gall bladder Stone Fistula Gastric outlet obstruction

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Sexual selection in cane toads Rhinella marina： A male＇s body size affects his success and his tactics

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Current Zoology 2013年第6期59卷 747-753页

作者： Haley BOWCOCK Gregory P. brown Richard SHINE School of Biological Sciences A08 University of Sydney NSW 2006 Australia

Abstract Male body size can play an important role in the mating systems of anuran amphibians. We conducted labora- tory-based trials with cane toads Rhinella （Bufo） marina from an invasive population in the wet-dry tropics of northern Australia, to clarify the effects of a male＇s body size on his reproductive success and behavior （mate choice）. Males were stimulated with a synthetic hormone to induce reproductive readiness. Larger body size enhanced a male toad＇s ability to displace a smaller rival from amplexus, apparently because of physical strength： more force was required to dislodge a larger than a smaller amplectant male. A male＇s body size also affected his mate-choice criteria. Males of all body sizes were as likely to attempt amplexus with another male as with a female of the same size, and preferred larger rather than smaller sexual targets. However, this size prefe- rence was stronger in larger males and hence, amplexus was size-assortative. This pattern broke down when males were given access to already-amplectant male-female pairs： males of all body sizes readily attempted amplexus with the pair, with no size discrimination. An amplectant pair provides a larger visual stimulus, and prolonged amplexus provides a strong cue for sex iden- tification （one of the individuals involved is almost certainly a female）. Thus, a male cane toad＇s body size affects both his ability to defeat rivals in physical struggles over females, and the criteria he uses when selecting potential mates, but the impacts of that selectivity depend upon the context in which mating occurs

关键词： Mating systems Size-assortative mating Large-male advantage Anurans Invasive species

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