Uncertainties

The solar contribution to global mean air surface temperature change is analyzed by using an empirical bi-scale climate model characterized by both fast and slow characteristic time responses to solar forcing: t 1 ¼ 0:470:1 yr and t 2 ¼ 872 yr or t 2 ¼ 1273 yr. Since 1980 the solar contribution to climate change is uncertain because of the severe uncertainty of the total solar irradiance satellite composites. The sun may have caused from a slight cooling, if PMOD TSI composite is used, to a significant warming (up to 65% of the total observed warming) if ACRIM, or other TSI composites are used. The model is calibrated only on the empirical 11-year solar cycle signature on the instrumental global surface temperature since 1980. The model reconstructs the major temperature patterns covering 400 years of solar induced temperature changes, as shown in recent paleoclimate global temperature records.

Heat is transported in aquifers by advection and conduction. Spatial variability of hydraulic conductivity causes fluctuations in small scale advection, whose effect can be represented by a dispersion term. However, the use of this term is still subject to controversy among modelers. The effect of heterogeneity on the heat plume generated by a groundwater heat exchanger (GHE) in a three-dimensional aquifer under steady state conditions is examined. Transverse dispersion is estimated using a stochastic approach in which a distinction between effective and ensemble dispersion coefficients is made. The former quantifies the typical width of the heat plume and the latter takes into account the uncertainty of the lateral plume position. Simulations show that transverse dispersion is proportional to the variance and correlation length of the log-conductivity field. On the one hand, the ensemble transverse dispersion coefficient, which can be used for risk analysis to find the mean temperature and the potential plume spread, is high near the heat source and then decreases. On the other hand, the effective transverse dispersion coefficient, the one required to simulate actual temperature values and plume width, displays a less marked dependence on the distance from the source. For modeling purposes it can be approximated as a T % 0:02r 2 ln K L x , where r 2 ln K is the variance of the log-conductivity field and L x its correlation length in the mean flow direction. However, a zero dispersion should be used to compute the energy dissipated by the GHE.

This paper presents a novel analytical formulation of an element removal algorithm based on dynamic equilibrium and the resulting transient change in system kinematics, by applying imposed accelerations instead of external forces at a node where an element was once connected. The algorithm is implemented into an open-source finite element code, numerically tested using a benchmark structural system with simplified element removal criteria, and able to capture the effect of uncertainty in member capacity. Realistic element removal criteria are introduced for mode-dependent gravity load collapse of seismically deficient and retrofitted reinforced concrete (RC) columns and unreinforced masonry (URM) infill walls. Two applications are conducted using structural systems of RC frames with URM infill walls. The first is a probabilistic study of a one-story model subjected to an ensemble of 14 ground motion recordings from similar neighboring sites during an earthquake event. The study produces empirical probability curves for partial and complete collapse conditioned on different hazard levels, and concludes that the intra-event variability is a major source of uncertainty affecting the outcome of progressive collapse simulations. The second application is a deterministic sensitivity study of progressive collapse response in a five-story structural model to uncertainty in live load, stiffness, damping, and seismic hazard level, subjected to one ground motion record. The analysis identifies the time at incipient collapse as an adequate sensitivity measure, and the uncertainty in ground motion intensity as the most important, followed by the stiffness of the URM infill wall. Copyright © 2009 John Wiley & Sons, Ltd.

La gestion des systèmes en fin de vie devient une préoccupation majeure pour les constructeurs de système en raison, d'une part, des enjeux liés au développement durable de plus en plus importants et, d'autre part, des perspectives de profits économiques qu'offrent la valorisation des systèmes en fin de vie. Dans ce contexte, la détermination d'une trajectoire de valorisation consiste à définir les produits valorisables à obtenir à partir du système, leur filière de valorisation et les opérations permettant de les obtenir. Dans cet article, nous proposons une démarche de modélisation des trajectoires de valorisation permettant d'intégrer différentes sources d'incertitude inhérente au domaine de la gestion des systèmes en fin de vie. Utilisant les réseaux bayésiens, cette méthode permet à la fois d'analyser et d'optimiser les trajectoires.

The past decade has seen considerable progress in the development of models simulating pesticide transport in structured soils subject to preferential flow (PF). Most PF pesticide transport models are based on the two-region concept and usually assume one (vertical) dimensional flow and transport. Stochastic parameter sets are sometimes used to account for the effects of spatial variability at the field scale. In the past decade, PF pesticide models were also coupled with Geographical Information Systems (GIS) and groundwater flow models for application at the catchment and larger regional scales. A review of PF pesticide model applications reveals that the principal difficulty of their application is still the appropriate parameterization of PF and pesticide processes. Experimental solution strategies involve improving measurement techniques and experimental designs. Model strategies aim at enhancing process descriptions, studying parameter sensitivity, uncertainty, inverse parameter identification, model calibration, and effects of spatial variability, as well as generating model emulators and databases. Model comparison studies demonstrated that, after calibration, PF pesticide models clearly outperform chromatographic models for structured soils. Considering nonlinear and kinetic sorption reactions further enhanced the pesticide transport description. However, inverse techniques combined with typically available experimental data are often limited in their ability to simultaneously identify parameters for describing PF, sorption, degradation and other processes. On the other hand, the predictive capacity of uncalibrated PF pesticide models currently allows at best an approximate (order-of-magnitude) estimation of concentrations. Moreover, models should target the entire soil-plant-atmosphere system, including often neglected above-ground processes such as pesticide volatilization, interception, sorption to plant residues, root uptake, and losses by runoff. The conclusions compile progress, problems, and future research choices for modelling pesticide displacement in structured soils.

A test case showing a comparison of TerraSAR-X and ground-based weather radar data acquired nearly simultaneously (within the same minute) over New York City. A good agreement between rain-cell signatures in (left) the SAR image and (right) the weather radar image can be observed. Authorized licensed use limited to: Deutsches Zentrum fuer Luft-und Raumfahrt. Downloaded on September 28, 2009 at 03:45 from IEEE Xplore. Restrictions apply.

This paper deals with the assessment of settlements of soft columnar inclusions when uncertainties in soil properties and geometric features are considered. Two common design methods, the analytical homogenisation method and the finite element method, are then combined with Monte Carlo simulations in order to find, using probability distributions of soil and geometrical characteristics, the probability of settlements exceeding a given value. The results show that length and modulus of granular piles are the two major sources of uncertainty and that the model uncertainty obtained from the interpretation of relevant sensitivities is smaller with the finite element model. From the outcome, this paper demonstrates that when geotechnical uncertainties and their effects on soil responses are appropriately accounted for, they can lead to an improved understanding and modelling of a practical geotechnical problem such as the ground improvement by columnar inclusions.

Environmental time series are often affected by the “presence” of missing data, but when dealing statistically with data, the need to fill in the gaps estimating the missing values must be considered. At present, a large number of statistical techniques are available to achieve this objective; they range from very simple methods, such as using the sample mean, to very sophisticated ones, such as multiple imputation. A brand new methodology for missing data estimation is proposed, which tries to merge the obvious advantages of the simplest techniques (e.g. their vocation to be easily implemented) with the strength of the newest techniques. The proposed method consists in the application of two consecutive stages: once it has been ascertained that a specific monitoring station is affected by missing data, the “most similar” monitoring stations are identified among neighbouring stations on the basis of a suitable similarity coefficient; in the second stage, a regressive method is applied in order to estimate the missing data. In this paper, four different regressive methods are applied and compared, in order to determine which is the most reliable for filling in the gaps, using rainfall data series measured in the Candelaro River Basin located in South Italy.

1] Research into the role of volatile organic compounds (VOCs) in the chemistry of the lower atmosphere has led to requirements for stable and accurate standard gas mixtures to underpin long-term monitoring of global background and polluted urban concentrations. We describe a novel method for the preparation of standard mixtures containing thirty compounds in matrices of nitrogen and whole air. The estimated uncertainty in the amount fractions of the compounds in these mixtures is typically 2% (relative) and typical stability is better than 0.2% per annum. We also report the results of a comparison exercise between eight laboratories using these mixtures, which indicate that typical uncertainties achievable by laboratories making measurements of these compounds are better than demonstrated previously. Citation: Grenfell, R. J. P., M. J. T. Milton, A. M. Harling, G. M. Vargha, C. Brookes, P. G. Quincey, and P. T. Woods (2010), Standard mixtures of ambient volatile organic compounds in synthetic and whole air with stable reference values, J. Geophys.

High-grade epithermal gold deposits in the Northern Great Basin have long been associated with regional Miocene basaltic to rhyolitic volcanism. Previous models for the low-sulfidation epithermal gold ores in this region have generally portrayed the bimodal magmas as a source of heat to drive large-scale convection of meteoritic water that leached gold from crustal sources and deposited it in hydrothermal vein systems, or required that the gold evolve from fractionated silicic magmas. New data of the present study indicate a more direct genetic link to the plume-related basaltic magmas of the region. Laser 40 Ar/ 39 Ar incremental heating plateau ages for single crystals of adularia from several of these lowsulfidation epithermal gold deposits range from 16.6 Ma to 15.5 Ma. Adularia from the Jumbo deposit yields three concordant plateau ages with a combined statistical result of 16.54 ± 0.04 Ma (95% confidence level, MSWD = 0.23). Plateau ages for adularia from other deposits in the region, and from gold-bearing veins in the Owyhee Mountains of southwestern Idaho, yield similar ages up to~16.5 Ma, however some veins are as young as ca. 15.5 Ma and the grain-to-grain ages for a given sample can vary by up to ca. 0.5 Ma. Observed variations in age among the adularia crystals of a given rock sample indicate varying amounts of extraneous argon, and also loss of radiogenic 40 Ar, among the population of grains for a particular sample. The single-crystal results are interpreted to indicate a 16.5-15.5 Ma interval for formation of gold-bearing adularia veins in the region. The initiation and duration of this gold-forming event appears contemporaneous (within uncertainties) with the basaltic volcanism at the Steens Mountain section and an ensuing one-million-year episode of basaltic volcanism from multiple centers in the region . Trace amounts of lead are alloyed with gold in the deposits studied. The isotopic compositions of this lead are not compatible with regional crustal units that host the gold ores, or the silicic igneous lithologies of the region, but have the same lead isotopic composition as basalts of the earliest Yellowstone plume (represented by the earliest lavas of the Columbia River basalt province, the Steens basalts, and Stonyford Volcanic Complex; . We propose that the gold studied and its traces of alloyed lead were derived together from the mantle, released from basaltic magma chambers of the province, and carried by low-density fluids into shallow geothermal systems during the earliest stages of Yellowstone hotspot magmatism.

Creating and managing protected areas is critical to ensure the persistence of species but dynamic threats like land-use change and climate change may reduce the effectiveness of protected areas planned under a static approach. Here we defined spatial priorities for the conservation of non-flying mammals inhabiting the Cerrado Biodiversity Hotspot, Brazil, that overcome the likely impacts of land-use and climate change to this imperiled fauna. We used cutting-edge methods of species distribution models combining thousands of model projections to generate a comprehensive ensemble of forecasts that shows the likely impacts of climate change in mammal distribution. We also generate a future land-use model that indicates how the region would be impacted by habitat loss in the future. We then used our models to propose priority sites for mammal conservation minimizing species climate-forced dispersal distance as well as the mean uncertainty associated to species distribution models and climate models. At the same time, our proposal maximizes complementary species representation across the existing network of protected areas. Including land-use changes and model uncertainties in the planning process changed significantly the spatial distribution of priority sites in the region. While the inclusion of land-use models altered the spatial location of priority sites at the regional scale, the effects of climate change tended to operate at the local scale. Our solutions already include possible dispersal corridors linking current and future priority sites for mammal conservation, as well as a formal risk analysis based on planning uncertainties. We hope to provide decision makers with conservation portfolios that could be negotiated at the decision level.► Land-use and climate changes challenge the way spatial conservation planning is done. ► Species distribution models are useful for such plans, but carry uncertainty. ► We included species range shifts and land-use changes in mammal conservation planning. ► Our spatial plans where improved by the inclusion of dynamics threats and uncertainty. ► We offer a methodological way to consider these threats in spatial planning.

Los campesinos no pueden sobrevivir exclusivamente del cultivo de café y deben complementar sus recursos con otras entradas económicas, sea la venta de productos secundarios, artesanías, del “jornaleo” o subsidios del gobierno. El sombrío es una práctica tradicional que ahorra recursos, demanda menos tecnología e implica menos riesgos de inversión. El cafetal con sombrío es relativamente más seguro y perdurable, por lo tanto garantiza un cultivo sostenible a largo plazo, con mayor estabilidad ambiental, económica y social.

El sombrío como estrategia proporciona seguridad alimentaria y social en las regiones cafeteras al proveer simultáneamente alimentos y beneficios económicos
extras. En algunas zonas de Colombia, los productos secundarios del sombrío juegan un papel determinante en la economía local, ya que se destinan en un importante porcentaje al autoconsumo, enriqueciendo la dieta alimenticia familiar.

Adicionalmente, su valor comercial puede llegar a superar los ingresos provenientes de la cosecha cafetera. La presente investigación se propone un acercamiento al
reconocimiento de los valores ambientales y económicos del sombrío desde las percepciones de los caficultores del Sur de Colombia (Departamentos de Huila y Cauca) y los niveles de importancia de los factores que inciden en sus decisiones
para el manejo de riesgos ecológicos y las incertidumbres económicas. Este trabajo introduce un esbozo histórico del sombrío en Colombia y una discusión sobre la consideración de la definición del sombrío.

El uso del sombrío ilustra la capacidad de adaptación e innovación de los productores locales versus una caficultura tecnificada y a plena exposición solar, estando en juego una caficultura tradicional sustentable pero subvalorada en el tiempo y espacio, donde los productores presentan múltiples estrategias económicas y ecológicas para disminuir los riesgos e incertidumbres y garantizar su supervivencia y seguridad alimentaria.

This paper presents a novel analytical formulation of an element removal algorithm based on dynamic equilibrium and the resulting transient change in system kinematics, by applying imposed accelerations instead of external forces at a node where an element was once connected. The algorithm is implemented into an open-source finite element code, numerically tested using a benchmark structural system with simplified element removal criteria, and able to capture the effect of uncertainty in member capacity. Realistic element removal criteria are introduced for mode-dependent gravity load collapse of seismically deficient and retrofitted reinforced concrete (RC) columns and unreinforced masonry (URM) infill walls. Two applications are conducted using structural systems of RC frames with URM infill walls. The first is a probabilistic study of a one-story model subjected to an ensemble of 14 ground motion recordings from similar neighboring sites during an earthquake event. The study produces empirical probability curves for partial and complete collapse conditioned on different hazard levels, and concludes that the intra-event variability is a major source of uncertainty affecting the outcome of progressive collapse simulations. The second application is a deterministic sensitivity study of progressive collapse response in a five-story structural model to uncertainty in live load, stiffness, damping, and seismic hazard level, subjected to one ground motion record. The analysis identifies the time at incipient collapse as an adequate sensitivity measure, and the uncertainty in ground motion intensity as the most important, followed by the stiffness of the URM infill wall. Copyright © 2009 John Wiley & Sons, Ltd.

The sandstone escarpment of the Dhar Tichitt in South-Central Mauritania was inhabited by Neolithic agropastoral communities for approximately one and half millennium during the Late Holocene, from ca. 4000 to 2300 BP. The absence of prior evidence of human settlement points to the influx of mobile herders moving away from the ''drying'' Sahara towards more humid lower latitudes. These herders took advantage of the peculiarities of the local geology and environment and succeeded in domesticating bulrush millet-Pennisetum sp. The emerging agropastoral subsistence complex had conflicting and/or complementary requirements depending on circumstances. In the long run, the social adjustment to the new subsistence complex, shifting site location strategies, nested settlement patterns and the rise of more encompassing polities appear to have been used to cope with climatic hazards in this relatively circumscribed area. An intense arid spell in the middle of the first millennium BC triggered the collapse of the whole Neolithic agropastoral system and the abandonment of the areas. These regions, resettled by sparse oasis-dwellers populations and iron-using communities starting from the first half of the first millennium AD, became part of the famous Ghana ''empire'', the earliest state in West African history. To cite this article: A.F.C.

The carbon footprint (CF) of milk production was analysed at the farm gate for two contrasting production systems; an outdoor pasture grazing system in New Zealand (NZ) and a mainly indoor housing system with pronounced use of concentrate feed in Sweden (SE). The method used is based on the conceptual framework of lifecycle assessment (LCA), but only for greenhouse gas (GHG) emissions. National average data were used to model the dairy system in each country. Collection of inventory data and calculations of emissions were harmonised to the greatest extent possible for the two systems. The calculated CF for 1 kg of energy corrected milk (ECM), including related by-products (surplus calves and culled cows), was 1.00 kg carbon dioxide equivalents (CO 2 e) for NZ and 1.16 kg CO 2 e for SE. Methane from enteric fermentation and nitrous oxide emissions from application of nitrogen (as fertiliser and as excreta dropped directly on the field) were the main contributors to the CF in both countries. The most important parameters to consider when calculating the GHG emissions were dry matter intake (DMI), emission factor (EF) for methane from enteric fermentation, amount of nitrogen applied and EF for direct nitrous oxide emissions from soils. By changing one parameter at a time within 'reasonable' limits (i.e. no extreme values assumed), the impact on the total CF was assessed and showed changes of up to 15%. In addition, the uncertainty in CF estimates due to uncertainty in EF for methane from enteric fermentation and nitrous oxide emissions (from soil and due to ammonia volatilisation) were analysed through Monte Carlo simulation. This resulted in an uncertainty distribution corresponding to 0.60-1.52 kg CO 2 e kg À1 ECM for NZ and 0.83-1.56 kg CO 2 e kg À1 ECM for SE (in the prediction interval 2.5-97.5%). Hence, the variation within the systems based on the main EF is relatively large compared with the difference in CF between the countries.

Many organizations are increasingly relying on design simulation rather than expensive and time-consuming prototype testing for product evaluation. However, uncertainties in analytical and computational methods need to be understood in order to improve confidence in their use, and models need to be validated. This paper presents a case study of a MacPherson strut automotive suspension analysis, and evaluates the uncertainties in the modelling of this complex dynamic problem using a simplified analytical model and a complex computational model. In both cases, variability in design variables is characterized using probabilistic design methods. As a first step, the model variables are described by assumed datasets, which are collated from several sources such as tolerances specified in drawings, expert opinion, published data, etc. Measurement of the properties of the suspension system components is then performed (spring stiffness, damping coeffcient, etc.), and the statistical parame...

Uncertainty and variability are inherent in the input parameters required for rock slope stability analyses. Since in the 1970s, probabilistic methods have been applied to slope stability analyses as a means of incorporating and evaluating the impact of uncertainty. Since then, methods of probabilistic analysis for planar and wedge sliding failures have become well established in the literature and are now widely used in practice. Analysis of toppling failure, however, has received relatively little attention. This paper introduces a Monte Carlo simulation procedure for the probabilistic analysis of block-toppling and describes its implementation into a spreadsheet-based program (ROCKTOPPLE). The analysis procedure considers both kinematic and kinetic probabilities of failure. These probabilities are evaluated separately and multiplied to give the total probability of block toppling. To demonstrate the use of ROCKTOPPLE, it is first verified against a published deterministic result, and then applied to a practical example with uncertain input parameters. Results obtained with the probabilistic approach are compared to those of an equivalent deterministic analysis in which mean values of input parameters are considered.

This paper presents a comprehensive review of uncertainties involved in flight vehicle structural damage monitoring, diagnosis, prognosis and control. Uncertainties can cause infeasibilities, false diagnosis and very imprecise prognosis if not correctly taken into account. The purpose of this paper is to review existing methods that have been developed to address the problem of uncertainty in the area of damage sensing, diagnosis, prognosis and control in flight vehicles. The mathematical and statistical methods in analyzing uncertainty are first presented and compared. Then, the different sources and perspectives of uncertainties in the damage assessment process are presented and classified. Following this, diagnosis and prognosis methods are reviewed. Final review section covers the control of damaged structure under uncertainty. In each section and in the concluding remarks section the research challenges in the field of flight vehicle structural damage sensing, diagnosis and prognosis methods as well as control under uncertainty are identified and promising new ideas are discussed.

Flood prediction Uncertainty Ensemble prediction system Streamflow Numerical weather prediction s u m m a r y Operational medium range flood forecasting systems are increasingly moving towards the adoption of ensembles of numerical weather predictions (NWP), known as ensemble prediction systems (EPS), to drive their predictions. We review the scientific drivers of this shift towards such 'ensemble flood forecasting' and discuss several of the questions surrounding best practice in using EPS in flood forecasting systems. We also review the literature evidence of the 'added value' of flood forecasts based on EPS and point to remaining key challenges in using EPS successfully.

Observation of damage caused by the recent Abruzzo earthquake on April 6th 2009 showed how local interaction between infills and RC structures can lead to soft-storey mechanisms and brittle collapses. Results of the present case study are based on observed damage caused by the earthquake in the zone of Pettino. Analytical model based on simulated design procedure was built up and time history analyses were employed to verify the causes of the structural collapse, as highlighted by observed damage. This failure mechanism was investigated taking into consideration all components of the ground motion. Nonlinear behavior of brick masonry infills was taken into account and two parametric hypotheses for infill mechanical properties were considered, given the uncertainties that typically characterize these nonstructural elements. Nonlinear modeling of infills was made by a three-strut macro-model aimed at considering both local and global interaction between RC frame and infills. Seismic input was characterized by the real signal registered during the mainshock near the case-study structure. Different shear capacity models were considered in the assessment.

Lake Tana Basin is of significant importance to Ethiopia concerning water resources aspects and the ecological balance of the area. Many years of mismanagement, wetland losses due to urban encroachment and population growth, and droughts are causing its rapid deterioration. The main objective of this study was to assess the performance and applicability of the soil water assessment tool (SWAT) model for prediction of streamflow in the Lake Tana Basin, so that the influence of topography, land use, soil and climatic condition on the hydrology of Lake Tana Basin can be well examined. The physically based SWAT model was calibrated and validated for four tributaries of Lake Tana. Sequential uncertainty fitting (SUFI-2), parameter solution (ParaSol) and generalized likelihood uncertainty estimation (GLUE) calibration and uncertainty analysis methods were compared and used for the set-up of the SWAT model. The model evaluation statistics for streamflows prediction shows that there is a good agreement between the measured and simulated flows that was verified by coefficients of determination and Nash Sutcliffe efficiency greater than 0Ð5. The hydrological water balance analysis of the basin indicated that baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. More than 60% of losses in the watershed are through evapotranspiration.

In virtually all construction projects there is risk of one form or the other. Too often, the inability to accurately predict these risks and deal with them leads to challenges for the project team and stakeholders. The objectives of the research are to assess the level of awareness of the stakeholders of the associated risks in construction project; identify and examine the risk factors associated with construction project; examine the impact of risk factors on performance of a project in terms of cost, time, and quality; and to determine the relative of each factors identified. The self-administered questionnaire to obtain relevant data was adopted. Sixty-two (62) professionals in the construction industry were sampled in the study area. Data were analysed with the use of non-parametric and parametric statistics. The study revealed that approximately half of the stakeholders are aware of the inherent risk factors. It was discovered that there is a relationship between attention given to risk factors and performance of projects.

Frequency-magnitude distributions, and their associated uncertainties, are of key importance in statistical seismology. When fitting these distributions, the assumption of Gaussian residuals is invalid since event numbers are both discrete and of unequal variance. In general, the observed number in any given magnitude range is described by a binomial distribution which, given a large total number of events of all magnitudes, approximates to a Poisson distribution for a sufficiently small probability associated with that range. In this paper, we examine four earthquake catalogues: New Zealand (Institute of Geological and Nuclear Sciences), Southern California (Southern California Earthquake Center), the Preliminary Determination of Epicentres and the Harvard Centroid Moment Tensor (both held by the United States Geological Survey). Using independent Poisson distributions to model the observations, we demonstrate a simple way of estimating the uncertainty on the total number of events occurring in a fixed time period.

Incremental Dynamic Analysis (IDA) is presented as a powerful tool to evaluate the variability in the seismic demand and capacity of non-deterministic structural models, building upon existing methodologies of Monte Carlo simulation and approximate moment-estimation. A nine-story steel moment-resisting frame is used as a testbed, employing parameterized moment-rotation relationships with non-deterministic quadrilinear backbones for the beam plastic-hinges. The uncertain properties of the backbones include the yield moment, the post-yield hardening ratio, the end-of-hardening rotation, the slope of the descending branch, the residual moment capacity and the ultimate rotation reached. IDA is employed to accurately assess the seismic performance of the model for any combination of the parameters by performing multiple nonlinear timehistory analyses for a suite of ground motion records. Sensitivity analyses on both the IDA and the static pushover level reveal the yield moment and the two rotational-ductility parameters to be the most influential for the frame behavior. To propagate the parametric uncertainty to the actual seismic performance we employ a) Monte Carlo simulation with latin hypercube sampling, b) point-estimate and c) first-order second-moment techniques, thus offering competing methods that represent different compromises between speed and accuracy. The final results provide firm ground for challenging current assumptions in seismic guidelines on using a median-parameter model to estimate the median seismic performance and employing the well-known square-root-sum-of-squares rule to combine aleatory randomness and epistemic uncertainty. Copyright

The Dimensional Metrology Group, and its predecessors at the National Institute of Standards and Technology (formerly the National Bureau of Standards) have been involved in documenting the science of gauge block calibration almost continuously since the seminal work of Peters and Boyd in 1926 [1]. Unfortunately, most of this documentation has been in the form of reports and other internal documents that are difficult for the interested metrologist outside the Institute to obtain.

To assess saturation effects on acoustic properties in carbonates, we measure ultrasonic velocity on 38 limestone samples whose porosity ranges from 5% to 30% under dry and water-saturated conditions. Complete saturation of the pore space with water causes an increase and decrease in compressional-and shear-wave velocity as well as significant changes in the shear moduli. Compressional velocities of most water-saturated samples are up to 500 m/s higher than the velocities of the dry samples. Some show no change, and a few even show a decrease in velocity. Shear-wave velocity ͑V S ͒ generally decreases, but nine samples show an increase of up to 230 m/s. Water saturation decreases the shear modulus by up to 2 GPa in some samples and increases it by up to 3 GPa in others. The average increase in the shear modulus with water saturation is 1.23 GPa; the average decrease is 0.75GPa. The V P /V S ratio shows an overall increase with water saturation. In particular, rocks displaying shear weakening have distinctly higher V P /V S ratios. Grainstone samples with high amounts of microporosity and interparticle macro-pores preferentially show shear weakening, whereas recrystallized limestones are prone to increase shear strengths with water saturation. The observed shear weakening indicates that a rockfluid interaction occurs with water saturation, which violates one of the assumptions in Gassmann's theory. We find a positive correlation between changes in shear modulus and the inability of Gassmann's theory to predict velocities of water-saturated samples at high frequencies. Velocities of water-saturated samples predicted by Gassmann's equation often exceed measured values by as much as 400 m/s for samples exhibiting shear weakening. In samples showing shear strengthening, Gassmann-predicted velocity values are as much as 600 m/s lower than measured values. In 66% of samples, Gassmann-predicted velocities show a misfit to measured water-saturated P-wave velocities. This discrepancy between measured and Gassmann-predicted velocity is not caused solely by velocity dispersion but also by rock-fluid interaction related to the pore structure of carbonates. Thus, a pore analysis should be conducted to assess shear-moduli changes and the resultant uncertainty for amplitude variation with offset analyses and velocity prediction using Gassmann's theory.

Water resources planning and management efficacy is subject to capturing inherent uncertainties stemming from climatic and hydrological inputs and models. Streamflow forecasts, critical in reservoir operation and water allocation decision making, fundamentally contain uncertainties arising from assumed initial condi- tions, model structure, and modeled processes. Accounting for these propagating uncertainties remains a formi- dable challenge. Recent enhancements in climate forecasting

The past decade has seen considerable progress in the development of models simulating pesticide transport in structured soils subject to preferential flow (PF). Most PF pesticide transport models are based on the two-region concept and usually assume one (vertical) dimensional flow and transport. Stochastic parameter sets are sometimes used to account for the effects of spatial variability at the field scale. In the past decade, PF pesticide models were also coupled with Geographical Information Systems (GIS) and groundwater flow models for application at the catchment and larger regional scales. A review of PF pesticide model applications reveals that the principal difficulty of their application is still the appropriate parameterization of PF and pesticide processes. Experimental solution strategies involve improving measurement techniques and experimental designs. Model strategies aim at enhancing process descriptions, studying parameter sensitivity, uncertainty, inverse parameter identification, model calibration, and effects of spatial variability, as well as generating model emulators and databases. Model comparison studies demonstrated that, after calibration, PF pesticide models clearly outperform chromatographic models for structured soils. Considering nonlinear and kinetic sorption reactions further enhanced the pesticide transport description. However, inverse techniques combined with typically available experimental data are often limited in their ability to simultaneously identify parameters for describing PF, sorption, degradation and other processes. On the other hand, the predictive capacity of uncalibrated PF pesticide models currently allows at best an approximate (order-of-magnitude) estimation of concentrations. Moreover, models should target the entire soil-plant-atmosphere system, including often neglected above-ground processes such as pesticide volatilization, interception, sorption to plant residues, root uptake, and losses by runoff. The conclusions compile progress, problems, and future research choices for modelling pesticide displacement in structured soils.

Nonlinear PID control systems for a quadrotor UAV are proposed to follow an attitude tracking command and a position tracking command. The control systems are developed directly on the special Euclidean group to avoid singularities of minimal attitude representations or ambiguity of quaternions. A new form of integral control terms is proposed to guarantee almost global asymptotic stability when there exist uncertainties in the quadrotor dynamics. A rigorous mathematical proof is given. Numerical example illustrating a complex maneuver, and a preliminary experimental result are provided.

Traditional top-down and technocratic approaches seem to be insufficient to tackle the many conflicts related to the sustainable use of natural resources. At the same time, reductionist and mono-disciplinary approaches lack the capacity to capture the complex interactions within evolving socio-ecological systems. Coastal zone management is an area that provides a clear example of such difficulties. In this paper we explore the scope of a participatory integrated assessment process, known as Social Multi-Criteria Evaluation (SMCE), in the context of Integrated Coastal Zone Management (ICZM). Through a two-year collaborative research process, between an interdisciplinary group of researchers and a diverse group of stakeholders in the Urdaibai Estuary (a Biosphere Reserve in the Basque Country, Northern Spain), we show that improving the integration of diverse expertise and values can lead, through a mutual learning process, to the definition of relevant policy options and sound decisions in the face of complexity, value conflict and unavoidable uncertainty.

Lake Tana Basin is of significant importance to Ethiopia concerning water resources aspects and the ecological balance of the area. Many years of mismanagement, wetland losses due to urban encroachment and population growth, and droughts are causing its rapid deterioration. The main objective of this study was to assess the performance and applicability of the soil water assessment tool (SWAT) model for prediction of streamflow in the Lake Tana Basin, so that the influence of topography, land use, soil and climatic condition on the hydrology of Lake Tana Basin can be well examined. The physically based SWAT model was calibrated and validated for four tributaries of Lake Tana. Sequential uncertainty fitting (SUFI-2), parameter solution (ParaSol) and generalized likelihood uncertainty estimation (GLUE) calibration and uncertainty analysis methods were compared and used for the set-up of the SWAT model. The model evaluation statistics for streamflows prediction shows that there is a good agreement between the measured and simulated flows that was verified by coefficients of determination and Nash Sutcliffe efficiency greater than 0Ð5. The hydrological water balance analysis of the basin indicated that baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. More than 60% of losses in the watershed are through evapotranspiration.

It has been proposed that animals and humans might choose a speed-accuracy tradeoff that maximizes reward rate. For this utility function the simple drift-diffusion model of two-alternative forced-choice tasks predicts a parameter-free optimal performance curve that relates normalized decision times to error rates under varying task conditions. However, behavioral data indicate that only ≈ 30% of subjects achieve optimality, and here we investigate the possibility that, in allowing for uncertainties, subjects might exercise robust strategies instead of optimal ones. We consider two strategies in which robustness is achieved by relinquishing performance: maximin and robust-satisficing. The former supposes maximization of guaranteed performance under a presumed level of uncertainty; the latter assumes that subjects require a critical performance level and maximize the level of uncertainty under which it can be guaranteed. These strategies respectively yield performance curves parameterized by a presumed uncertainty level and required performance. Maximin performance curves for uncertainties in response-to-stimulus interval match data for the lower-scoring 70% of subjects well, and are more likely to explain it than robust-satisficing or alternative optimal performance curves that emphasize accuracy. For uncertainties in signal-to-noise ratio, neither maximin nor robust-satisficing performance curves adequately describe the data. We discuss implications for decisions under uncertainties, and suggest further behavioral assays.

Please cite this article as: Masih, I., Uhlenbrook, S., Maskey, S., Ahmad, M.D., Regionalization of a conceptual rainfall-runoff model based on similarity of the flow duration curve: A case study from the semi-arid Karkheh basin, Abstract 11

Applied flood risk analyses, especially in urban areas, very often pose the question how detailed the analysis needs to be in order to give a realistic figure of the expected risk. The methods used in research and practical applications range from very basic approaches with numerous simplifying assumptions up to very sophisticated, data and calculation time demanding applications both on the hazard and vulnerability part of the risk. In order to shed some light on the question of required model complexity in flood risk analyses and outputs sufficiently fulfilling the task at hand, a number of combinations of models of different complexity both on the hazard and vulnerability side were tested in a case study. The different models can be organized in a model matrix of different complexity levels: On the hazard side the approaches/models selected were A) linear interpolation of gauge water levels and intersection with a digital elevation model (DEM), B) a mixed 1D/2D hydraulic model with simplifying assumptions (LISFLOOD-FP) and C) a Saint-Venant 2D zero-inertia hyperbolic hydraulic model considering the built environment and

The observed increase in global mean surface temperature (GMST) over the industrial era is less than 40% of that expected from observed increases in long-lived greenhouse gases together with the best-estimate equilibrium climate sensitivity given by the 2007 Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Possible reasons for this warming discrepancy are systematically examined here. The warming discrepancy is found to be due mainly to some combination of two factors: the IPCC best estimate of climate sensitivity being too high and/or the greenhouse gas forcing being partially offset by forcing by increased concentrations of atmospheric aerosols; the increase in global heat content due to thermal disequilibrium accounts for less than 25% of the discrepancy, and cooling by natural temperature variation can account for only about 15%. Current uncertainty in climate sensitivity is shown to preclude determining the amount of future fossil fuel CO 2 emissions that would be compatible with any chosen maximum allowable increase in GMST; even the sign of such allowable future emissions is unconstrained. Resolving this situation, by empirical determination of the earth's climate sensitivity from the historical record over the industrial period or through use of climate models whose accuracy is evaluated by their performance over this period, is shown to require substantial reduction in the uncertainty of aerosol forcing over this period.

Aviation emissions contribute to the radiative forcing (RF) of climate. Of importance are emissions of carbon dioxide (CO 2 ), nitrogen oxides (NO x ), aerosols and their precursors (soot and sulphate), and increased cloudiness in the form of persistent linear contrails and induced-cirrus cloudiness. The recent Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) quantified aviation's RF contribution for 2005 based upon 2000 operations data. Aviation has grown strongly over the past years, despite world-changing events in the early 2000s; the average annual passenger traffic growth rate was 5.3% yr À1 between 2000 and 2007, resulting in an increase of passenger traffic of 38%. Presented here are updated values of aviation RF for 2005 based upon new operations data that show an increase in traffic of 22.5%, fuel use of 8.4% and total aviation RF of 14% (excluding induced-cirrus enhancement) over the period 2000-2005. The lack of physical process models and adequate observational data for aviationinduced cirrus effects limit confidence in quantifying their RF contribution. Total aviation RF (excluding induced cirrus) in 2005 was w55 mW m À2 (23-87 mW m À2 , 90% likelihood range), which was 3.5% (range 1.3-10%, 90% likelihood range) of total anthropogenic forcing. Including estimates for aviation-induced cirrus RF increases the total aviation RF in 2005-78 mW m À2 (38-139 mW m À2 , 90% likelihood range), which represents 4.9% of total anthropogenic forcing (2-14%, 90% likelihood range). Future scenarios of aviation emissions for 2050 that are consistent with IPCC SRES A1 and B2 scenario assumptions have been presented that show an increase of fuel usage by factors of 2.7-3.9 over 2000. Simplified calculations of total aviation RF in 2050 indicate increases by factors of 3.0-4.0 over the 2000 value, representing 4-4.7% of total RF (excluding induced cirrus). An examination of a range of future technological options shows that substantive reductions in aviation fuel usage are possible only with the introduction of radical technologies. Incorporation of aviation into an emissions trading system offers the potential for overall (i.e., beyond the aviation sector) CO 2 emissions reductions. Proposals exist for introduction of such a system at a European level, but no agreement has been reached at a global level.