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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 design.the 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 design.the posterior distributions are often complex,multidimensional functions whose analysis requires the use of Markov chain Monte Carlo(MCMC)methods.these procedures are used to draw representative samples of the parameters investigated,providing information on their best estimate values,variability and correlations.the 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 parameters.the Bayesian model is also used to update the estimation of the input parameters based on the back analysis of slope failure.In this case,the condition FS?1 is treated as a data point that is compared with the model prediction of FS.the analysis requires a sufficient number of observations of failure to outbalance the effect of the initial input parameters.the parameters are updated according to their uncertainty,which is determined by the amount of data supporting them.the methodology is illustrated with an example of a rock slope characterised with a Hoek-brown rock mass strength.the 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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Bayesian data analysis to quantify the uncertainty of intact rock strength

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第1期10卷 11-31页

作者： Luis Fernando Contreras Edwin t.Brown Marc Ruest the University of Queensland St Lucia CampusBrisbaneQLD 4072Australia Golder Associates Pty.Ltd. BrisbaneAustralia

One of the main difficulties in the geotechnical design process lies in dealing with uncertainty. Uncertainty is associated with natural variation of properties, and the imprecision and unpredictability caused by insufficient information on parameters or models. Probabilistic methods are normally used to quantify uncertainty. However, the frequentist approach commonly used for this purpose has some drawbacks.First, it lacks a formal framework for incorporating knowledge not represented by data. Second, it has limitations in providing a proper measure of the confidence of parameters inferred from data. the Bayesian approach offers a better framework for treating uncertainty in geotechnical design. the advantages of the Bayesian approach for uncertainty quantification are highlighted in this paper with the Bayesian regression analysis of laboratory test data to infer the intact rock strength parameters σand mused in the Hoek-brown strength criterion. two case examples are used to illustrate different aspects of the Bayesian methodology and to contrast the approach with a frequentist approach represented by the nonlinear least squares(NLLS) method. the paper discusses the use of a Student’s t-distribution versus a normal distribution to handle outliers, the consideration of absolute versus relative residuals, and the comparison of quality of fitting results based on standard errors and Bayes factors. Uncertainty quantification with confidence and prediction intervals of the frequentist approach is compared with that based on scatter plots and bands of fitted envelopes of the Bayesian approach. Finally, the Bayesian method is extended to consider two improvements of the fitting analysis. the first is the case in which the Hoek-brown parameter, a, is treated as a variable to improve the fitting in the triaxial region. the second is the incorporation of the uncertainty in the estimation of the direct tensile strength from Brazilian test results within the overall evaluation of the intact rock strength.

关键词： Uncertainty Intact rock strength Bayesian analysis Hoek-brown criterion

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深部矿产资源开采与利用中的挑战

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Engineering 2017年第4期 9-12页

作者：蔡美峰 Edwin t.Brown Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mines University of Science and Technology Beijing Golder Associates Pty. Ltd.

正如Mote等[1]在本刊中已经提到的那样,工程科技领域的进步对人类社会与经济的发展起到了不可或缺的作用。然而,随着世界人口的日益增长,科技的持续发展正以最终会被证明不可持续的速度消耗地球的资源,包括矿产资源。几百年的开采之后,... 详细信息

正如Mote等[1]在本刊中已经提到的那样,工程科技领域的进步对人类社会与经济的发展起到了不可或缺的作用。然而,随着世界人口的日益增长,科技的持续发展正以最终会被证明不可持续的速度消耗地球的资源,包括矿产资源。几百年的开采之后,更易获取的浅部矿产资源正在逐步枯竭,有些已被完全耗尽。这意味着如今需要对更多的地球更深部矿产资源进行经济的开发,以满足社会持续增长的矿产需求。这种需求不仅仅

关键词：矿产资源金属矿山中国工程院开采方法岩石工程

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transcranial electrical stimulation in neurological disease

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Neural Regeneration Research 2022年第10期17卷 2221-2222页

作者： Gregory L.brown Michael t.brown Neurished HersheyPAUSA

Increased lifespan is one of society’s greatest achievements,but this longevity increases the prevalence of diseases of aging,such as neurological disorders.Globally,neurological disorders are the leading cause of disability and the second leading cause of deaths(Feigin et al.,2019).Furthermore,these diseases affect people in low-,medium-,and high-income countries(Feigin et al.,2019).Current technology to modify neurological burden is scarce,which poses numerous challenges for healthcare,global policy,and economic stability(Feigin et al.,2019).to face these challenges,brain stimulation technology,such as transcranial electrical stimulation(tES),has displayed exciting potential.Antal et al.(2017)provide a detailed overview of the safety and application of tES.Commonly,electrodes are attached to the head and a weak current(e.g.,1-2 mA)is applied through the scalp,skull,and into the brain for 10-30 minutes to activate neurons(Antal et al.,2017).the technique is extremely safe with no serious adverse effects reported from thousands of sessions(Antal et al.,2017).the most common side effects are a tingling/itching sensation or redness at the stimulation site(Antal et al.,2017).However,these side effects can be minimized by reducing the electrode-skin impedance,slowly ramping up and ramping down tES,or using topical analgesics(Antal et al.,2017).the development of tES may repair neural dysfunction and stem the oncoming incidence of neurodegenerative disease.

关键词： stimulation sensation electrical

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Challenges in the Mining and Utilization of Deep Mineral Resources

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Engineering 2017年第4期3卷 432-433页

作者： Meifeng Cai edwin t. brown Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mines University of Science and Technology Beijing Beijing 100083 China Colder Associates Pty. Ltd. Brisbane QLD 4064 Australia the University of Queensland Brisbane OLD 4072 Australia

As Mote et al. [1] have noted in this journal, advances in the fields of engineering science and technology have played an indispensable role in shaping the social and economic development of humankind. However, the continuing development of science and technology, along with the world’s ever-growing population, is consuming the earth’s resources, including its mineral resources, at what may ultimately prove to be unsustainable rates. After hundreds of years of mining, the more accessible shallow mineral resources are being depleted, and some have now been completely exhausted. this means that the economic exploitation of more of the earth’s deeper mineral resources is now required in order to meet society’s growing demand for minerals. this demand is not only for the traditional metallic ores and energy sources, but also for minerals such as rare earths, which are being used at an increasing rate with the advent of new technologies in the fields of communication, power generation, and power storage, among others. the efficient mining and utilization of deep mineral resources is not one of the Grand Challenges for Engineering that were identified in recent years by the US National Academy of Engineering, the UK Royal Academy of Engineering, and the Chinese Academy of Engineering (CAE), as listed by Mote et al. [1]. However, it is clear that traditional and newer mineral resources will be required in order to develop solutions to most of the Grand Challenges that have been identified.Exploitable mineral resources exist at great depth in the form of a number of orebody types in a range of geological and geometrical settings. the current seven deepest mines in the world mine tabular or stratiform gold deposits in the Witwatersrand Basin of South Africa. the deepest of these mines are now around 4 km deep. the next deepest mines in the world are two base metal mines in Canada, which are about 3 km deep. For the purpose of this discussion, deep mining is taken to involve mining at depths of more than 1 km.

关键词： Mineral resources

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Risk assessment and management in underground rock engineering——an overview

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Journal of Rock Mechanics and Geotechnical Engineering 2012年第3期4卷 193-204页

作者： Edwin t.Brown Golder Associates Pty Ltd. Brisbane Queensland 4064 Australia

this paper attempts to provide an overview of risk assessment and management practice in underground rock engineering based on a review of the international literature and some personal experience. It is noted that the terminologies used in risk assessment and management studies may vary from country to country. Probabilistic risk analysis is probably the most widely-used approach to risk assessment in rock engineering and in geotechnical engineering more broadly. It is concluded that great potential exists to augment the existing probabilistic methods by the use of Bayesian networks and decision analysis techniques to allow reasoning under uncertainty and to update probabilities, material properties and analyses as further data become available throughout the various stages of a project. Examples are given of the use of these methods in underground excavation engineering in China and elsewhere, and opportunities for their further application are identified.

关键词： Bayesian networks probabilistic risk analysis risk analysis risk management underground rock engineering

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Endogenous mucin conveyed to the mucosa with microbes can assure lumen fermentation and large intestinal security-swine versus fowl

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Animal Nutrition 2023年第3期14卷 403-410页

作者： edwin t.Moran Michael R.Bedford Poultry Science Department Auburn UniversityAL 36849-5416USA AB Vista Woodstock CourtBlenheim RoadMarlborough RoadWiltshireSN84NAUK

Endogenous protein leaving the ileum largely consists of accrued mucins from the upper gastrointestinal tract(GIt)that had resisted digestion.the amounts released rely on their mucosal generation during enteral feeding which vary with age as well as diet.these digestion resistant proteins of endogenous origin continue to be unavailable in the large intestine,whereas those of dietary origin provide amino acids that largely support the existing microbial population while denying limited amounts for absorption.Other mucins pre-exist within the large intestine as two layers at the lumen surface.A loose layer harboring a diverse microbial population is superimposed on the unstirred water layer(USWL)which simultaneously acts as an obstacle to microbes at the loose layer while performing as a molecular sieve for nutrients.the USWL is formed through interplay between enterocyte and goblet cells;however,the basis for presence of the loose layer is elusive.Large intestinal fermentation predominates within the colon of swine,whereas fowl employ their ceca.Motility within the colon of swine segregates fine materials into haustrae out-pocketings that parallel their placement within the ceca of fowl.Viscous mucins from small intestinal endogenous losses may envelop microbes within the large intestinal lumen to present successive adherents on the USWL that assemble its loose layer.the loose layer continually functions as a microbial reservoir in support of lumen fermentation.Microbial catabolism of mucin within the loose layer is known to be slow,but its proximity to the enterocyte is of advantage to enterocyte absorption with by-product amino acids fostering the USWL.

关键词： Endogenous protein Enterocyte Goblet cell Mucin Large intestine

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Dietary free fatty acids complex with amylose creating another form of resistant starch: Gastrointestinal formation with fowl and swine

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Animal Nutrition 2021年第4期7卷 1124-1132页

作者： edwin t.Moran Jr. Poultry Science Department Auburn UniversityAL36849-5416USA

Fat added to poultry and swine feeds often contains abundant free fatty acids(FFA)that can impair digestible energy(DE).Placement of the fatty acid(FA)hydrocarbon chain in the helix core reformed from amylose creates a complex of both nutrients.Resulting modifications create a new structure termed the V-helix that becomes resistant toα-amylase.Granules in grain naturally contain minimal amounts of these complexes with more being generated during food manufacturing when moisture and heat release amylose in the presence of FFA.A paucity of FFA usually exists in complete feeds without sources of poorquality fat.Animal fats and by-product meals from rendering are prominent in their saturated FFA content which favorably complex within the helix.V-helix-FA complexes may arise during their concurrent encounter of FFA together with amylose during feed manufacture,particularly pelleting.FFA in the gastrointestinal tract(GIt)are speculated to further form complexes when present together with amylose.Although amylose may be dissolved in the gastric and small intestinal milieu,FFA separately coalesce into hydrophobic fat droplets along with other dietary lipids.Formation of complexes is likely restricted until FFA are released into the aqueous phase during fat digestion.Althoughα-amylase may be prominent,V-helix-FA complexes being resistant to enzymic attack pass into the large intestine.Subsequent microbial catabolism of V-helices may generate volatile fatty acids that are absorbed by the mucosa;however,an inability to use FFA once released leads to their excretion and basis for decreased DE.Immature microbial populations with young animals usually lack the capacity to fully catabolize the V-helix,further extending the loss in DE.

关键词： Amylose Digestible energy Free fatty acid Feed manufacture

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Large intestinal dynamics differ between fowl and swine:Anatomical modifications,microbial collaboration,and digestive advantages from fibrolytic enzymes

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Animal Nutrition 2022年第4期11卷 160-170页

作者： edwin t.Moran Jr. Michael R.Bedford Poultry Science Department Auburn UniversityAL 36830-5416USA AB Vista Woodstock CourtBlenheim RoadMarlboroughWiltshire SN84ANUK

the large intestinal systems of fowl and swine recover nutrients from ileal indigesta by a strategically different manner.Indigesta with fowl enter a short colon where retro-peristalsis using urine from the urodeum carries small particulates and solutes into both ceca while coarse materials collect in the cloaca.Fowl repetitively add fine and soluble materials into both ceca to continue fermentation until complexity of the remainder exceeds microbial action,then contents apart from faeces are entirely evacuated.Indigesta with swine initially enter a short cecum followed by a lengthy progression through to the rectal ampulla.Wall out-pocketings of circular muscle or haustrae occur throughout the length of the pig's cecum and helicoidal colon.Each pocket carries contents acquired earlier in the cecum.Motility collects fines and solutes into haustrae during their progression through the colon whereas coarse particulates assemble in the core.Haustrae contents continually ferment during movement to the distal colon with resulting volatile fatty acids(VFA)and electrolytes being absorbed.Mucin loosely covers the lumen surface in caeca as well as helicoidal colon that may capture microbes from active intestinal contents as well as release others to sustain fermentation.the microbial community continually modifies to accommodate fibre complexity as encountered.Resistant starches(RS)and simple oligosaccharides rapidly ferment to yield VFA while encouraging butyric acid in the cecum and anterior colon,whereas non-starch polysaccharides(NSP)complexity requires extended durations through the remaining colon that enhance acetic acid.Residual fibre eventually results in undue complexity for fermentation and consolidates at termination of the colon.these compact pellets are placed on core contents to form faeces having a nodular surface.Acetic,propionic,and butyric acids represent the bulk of VFA and are derived from non-digestible carbohydrates.Fibrolytic enzymes,when supplemented to feed,may increase the proportion of oligosac

关键词： Butyric acid Endogenous protein Intestinal microbes Large intestine Volatile fatty acids Xylanase

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草甘膦对可食用蓝藻葛仙米生长和生理的影响(英文)

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水生生物学报 2008年第4期32卷 462-468页

作者：阮祚禧 Murray t.brown 汕头大学科技中心海洋生物研究所汕头515063 School of Biological Sciences University of PlymouthDrake CircusPlymouth PL4 8AAUnited Kingdom

葛仙米(N.sphaeroides)的产量和产地面积逐年减少,这可能与当地广泛使用除草剂草甘膦有关。为此,本文测定了不同浓度(0.15、0.30、0.45、0.6mmol/L)的草甘膦处理的葛仙米的颗粒大小、干重、叶绿素荧光、叶绿素浓度。所有测量参数与浓度... 详细信息

葛仙米(N.sphaeroides)的产量和产地面积逐年减少,这可能与当地广泛使用除草剂草甘膦有关。为此,本文测定了不同浓度(0.15、0.30、0.45、0.6mmol/L)的草甘膦处理的葛仙米的颗粒大小、干重、叶绿素荧光、叶绿素浓度。所有测量参数与浓度和时间显著相关:0.15mmol/L处理组的颗粒直径较对照组小15%(2d后);叶绿素a浓度和最大量子产率(Fv/Fm)在最高浓度组(0.6mmol/L)4d后开始受到影响;第8天,相对生长速率(以干重计算,大于0.15mmol/L)、光合作用活性(大于0.3mmol/L)均受显著抑制,其中0.15mmol/L处理组相对生长下降60%,而更高浓度处理组出现负生长,0.6mmol/L组藻体漂白死亡。结合实验结果,文章讨论了草甘膦的毒性机理及其对葛仙米(N.sphaeroides)的潜在影响。

关键词：除草剂蓝藻毒性生长叶绿素a荧光

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