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1
Bozejko, Wojciech, Zdzislaw Hejducki, and Mieczyslaw Wodecki. "Flowshop scheduling of construction processes with uncertain parameters." Archives of Civil and Mechanical Engineering 19, no. 1 (March 2019): 194–204. http://dx.doi.org/10.1016/j.acme.2018.09.010.
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Pozzi, Matteo, Milad Memarzadeh, and Kelly Klima. "Hidden-Model Processes for Adaptive Management under Uncertain Climate Change." Journal of Infrastructure Systems 23, no. 4 (December 2017): 04017022. http://dx.doi.org/10.1061/(asce)is.1943-555x.0000376.
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Zhang, Yanshan, and Zhengmao Yang. "Reliability sensitivity numerical analysis of mechanical structure based on gamma processes." Advances in Mechanical Engineering 8, no. 12 (December 2016): 168781401667962. http://dx.doi.org/10.1177/1687814016679624.
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Using random variables to describe uncertain parameters in structural systems, its initial strength and the evolution process of the strength degradation is regarded as the Gamma process. In this article, we propose a new method on reliability sensitivity numerical analysis of mechanical structure based on Gamma processes. Then, we use the fourth moment method based on frequency curve of Pearson to solve the problem of reliability calculation with random parameters of arbitrary distributions. Formulas for calculating the reliability sensitivity with respect to the mean and the variance of the random variables are derived. The reliability analysis of the welded box girders of crane is taken as an example to verify the proposed method. The results show that the method can effectively solve the problem of the reliability sensitivity of structural systems with strength degradation.
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Alcaraz-González, V., J. Harmand, A. Rapaport, J. P. Steyer, V. González-Álvarez, and C. Pelayo-Ortiz. "Robust interval-based regulation for anaerobic digestion processes." Water Science and Technology 52, no. 1-2 (July 1, 2005): 449–56. http://dx.doi.org/10.2166/wst.2005.0552.
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A robust regulation law is applied to the stabilization of a class of biochemical reactors exhibiting partially known highly nonlinear dynamic behavior. An uncertain environment with the presence of unknown inputs is considered. Based on some structural and operational conditions, this regulation law is shown to exponentially stabilize the aforementioned bioreactors around a desired set-point. This approach is experimentally applied and validated on a pilot-scale (1 m3) anaerobic digestion process for the treatment of raw industrial wine distillery wastewater where the objective is the regulation of the chemical oxygen demand (COD) by using the dilution rate as the manipulated variable. Despite large disturbances on the input COD and state and parametric uncertainties, this regulation law gave excellent performances leading the output COD towards its set-point and keeping it inside a pre-specified interval.
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Stamm, Fabian Antonio, Miguel de la Varga, and Florian Wellmann. "Actors, actions, and uncertainties: optimizing decision-making based on 3-D structural geological models." Solid Earth 10, no. 6 (November 18, 2019): 2015–43. http://dx.doi.org/10.5194/se-10-2015-2019.
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Abstract. Uncertainties are common in geological models and have a considerable impact on model interpretations and subsequent decision-making. This is of particular significance for high-risk, high-reward sectors. Recent advances allows us to view geological modeling as a statistical problem that we can address with probabilistic methods. Using stochastic simulations and Bayesian inference, uncertainties can be quantified and reduced by incorporating additional geological information. In this work, we propose custom loss functions as a decision-making tool that builds upon such probabilistic approaches. As an example, we devise a case in which the decision problem is one of estimating the uncertain economic value of a potential fluid reservoir. For subsequent true value estimation, we design a case-specific loss function to reflect not only the decision-making environment, but also the preferences of differently risk-inclined decision makers. Based on this function, optimizing for expected loss returns an actor's best estimate to base decision-making on, given a probability distribution for the uncertain parameter of interest. We apply the customized loss function in the context of a case study featuring a synthetic 3-D structural geological model. A set of probability distributions for the maximum trap volume as the parameter of interest is generated via stochastic simulations. These represent different information scenarios to test the loss function approach for decision-making. Our results show that the optimizing estimators shift according to the characteristics of the underlying distribution. While overall variation leads to separation, risk-averse and risk-friendly decisions converge in the decision space and decrease in expected loss given narrower distributions. We thus consider the degree of decision convergence to be a measure for the state of knowledge and its inherent uncertainty at the moment of decision-making. This decisive uncertainty does not change in alignment with model uncertainty but depends on alterations of critical parameters and respective interdependencies, in particular relating to seal reliability. Additionally, actors are affected differently by adding new information to the model, depending on their risk affinity. It is therefore important to identify the model parameters that are most influential for the final decision in order to optimize the decision-making process.
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Moges, Edom, Yonas Demissie, Laurel Larsen, and Fuad Yassin. "Review: Sources of Hydrological Model Uncertainties and Advances in Their Analysis." Water 13, no. 1 (December 25, 2020): 28. http://dx.doi.org/10.3390/w13010028.
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Despite progresses in representing different processes, hydrological models remain uncertain. Their uncertainty stems from input and calibration data, model structure, and parameters. In characterizing these sources, their causes, interactions and different uncertainty analysis (UA) methods are reviewed. The commonly used UA methods are categorized into six broad classes: (i) Monte Carlo analysis, (ii) Bayesian statistics, (iii) multi-objective analysis, (iv) least-squares-based inverse modeling, (v) response-surface-based techniques, and (vi) multi-modeling analysis. For each source of uncertainty, the status-quo and applications of these methods are critiqued in gauged catchments where UA is common and in ungauged catchments where both UA and its review are lacking. Compared to parameter uncertainty, UA application for structural uncertainty is limited while input and calibration data uncertainties are mostly unaccounted. Further research is needed to improve the computational efficiency of UA, disentangle and propagate the different sources of uncertainty, improve UA applications to environmental changes and coupled human–natural-hydrologic systems, and ease UA’s applications for practitioners.
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Luo, Zhi Kun, Ping He, Wei Tan, and Guo Dong Jin. "Dynamic Analysis of a Truck Frame with Fuzzy Uncertain Parameters." Advanced Materials Research 466-467 (February 2012): 1279–84. http://dx.doi.org/10.4028/www.scientific.net/amr.466-467.1279.
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Frame acts as the structural backbone of a truck, which supports the components and payload placed upon it. When the truck travels along the road, the frame is subjected to vibration induced by road roughness and excitation by vibrating components such as power-train, transmission shaft and more that mounted on it. Though many researchers have made great progress in the static and dynamic analysis of truck frame, most research was based on the assumption that all the design parameters of truck frame were deterministic. However, design variables for truck frame are always uncertain in the actual realistic engineering cases due to tolerances in manufacturing and assembly processes. In this paper, fuzzy algorithm is introduced to analysis the response of the frame with uncertain parameters. By using fuzzy set theory, uncertain input parameters such as the elastic modulus, Poisson ratio are described mathematically as fuzzy variables or fuzzy random variables and integrated into mode analysis. The simulations are carried out to analysis the system performance under fuzzy uncertain parameters. Results are presented showing the effectiveness of the method for modeling systems with uncertain parameters.
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Sikorska, A. E., A. Scheidegger, K. Banasik, and J. Rieckermann. "Bayesian uncertainty assessment of flood predictions in ungauged urban basins for conceptual rainfall-runoff models." Hydrology and Earth System Sciences Discussions 8, no. 6 (December 13, 2011): 11075–113. http://dx.doi.org/10.5194/hessd-8-11075-2011.
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Abstract. Urbanization and the resulting land-use change strongly affect the water cycle and runoff-processes in watersheds. Unfortunately, small urban watersheds, which are most affected by urban sprawl, are mostly ungauged. This makes it intrinsically difficult to assess the consequences of urbanization. Most of all, it is unclear how to reliably assess the predictive uncertainty given the structural deficits of the applied models. In this study, we therefore investigate the uncertainty of flood predictions in ungauged urban basins from structurally uncertain rainfall-runoff models. To this end, we suggest a procedure to explicitly account for input uncertainty and model structure deficits using Bayesian statistics with a continuous-time autoregressive error model. In addition, we propose a concise procedure to derive prior parameter distributions from base data and successfully apply the methodology to an urban catchment in Warsaw, Poland. Based on our results, we are able to demonstrate that the autoregressive error model greatly helps to meet the statistical assumptions and to compute reliable prediction intervals. In our study, we found that predicted peak flows were up to 7 times higher than observations. This was reduced by 150% with Bayesian updating, using only a few discharge measurements. In addition, our analysis suggests that imprecise rainfall information and model structure deficits contribute mostly to the total prediction uncertainty. In the future, flood predictions in ungauged basins will become more important due to ongoing urbanization as well as anthropogenic and climatic changes. Thus, providing reliable measures of uncertainty is crucial to support decision making.
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McNeall, Doug, Jonny Williams, Ben Booth, Richard Betts, Peter Challenor, Andy Wiltshire, and David Sexton. "The impact of structural error on parameter constraint in a climate model." Earth System Dynamics 7, no. 4 (November 24, 2016): 917–35. http://dx.doi.org/10.5194/esd-7-917-2016.
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Abstract. Uncertainty in the simulation of the carbon cycle contributes significantly to uncertainty in the projections of future climate change. We use observations of forest fraction to constrain carbon cycle and land surface input parameters of the global climate model FAMOUS, in the presence of an uncertain structural error. Using an ensemble of climate model runs to build a computationally cheap statistical proxy (emulator) of the climate model, we use history matching to rule out input parameter settings where the corresponding climate model output is judged sufficiently different from observations, even allowing for uncertainty. Regions of parameter space where FAMOUS best simulates the Amazon forest fraction are incompatible with the regions where FAMOUS best simulates other forests, indicating a structural error in the model. We use the emulator to simulate the forest fraction at the best set of parameters implied by matching the model to the Amazon, Central African, South East Asian, and North American forests in turn. We can find parameters that lead to a realistic forest fraction in the Amazon, but that using the Amazon alone to tune the simulator would result in a significant overestimate of forest fraction in the other forests. Conversely, using the other forests to tune the simulator leads to a larger underestimate of the Amazon forest fraction. We use sensitivity analysis to find the parameters which have the most impact on simulator output and perform a history-matching exercise using credible estimates for simulator discrepancy and observational uncertainty terms. We are unable to constrain the parameters individually, but we rule out just under half of joint parameter space as being incompatible with forest observations. We discuss the possible sources of the discrepancy in the simulated Amazon, including missing processes in the land surface component and a bias in the climatology of the Amazon.
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Guo, Hao-Bo, Yue Ma, Gerald Tuskan, Hong Qin, Xiaohan Yang, and Hong Guo. "A Suggestion of Converting Protein Intrinsic Disorder to Structural Entropy Using Shannon’s Information Theory." Entropy 21, no. 6 (June 14, 2019): 591. http://dx.doi.org/10.3390/e21060591.
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We propose a framework to convert the protein intrinsic disorder content to structural entropy (H) using Shannon’s information theory (IT). The structural capacity (C), which is the sum of H and structural information (I), is equal to the amino acid sequence length of the protein. The structural entropy of the residues expands a continuous spectrum, ranging from 0 (fully ordered) to 1 (fully disordered), consistent with Shannon’s IT, which scores the fully-determined state 0 and the fully-uncertain state 1. The intrinsically disordered proteins (IDPs) in a living cell may participate in maintaining the high-energy-low-entropy state. In addition, under this framework, the biological functions performed by proteins and associated with the order or disorder of their 3D structures could be explained in terms of information-gains or entropy-losses, or the reverse processes.
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Kalinin, Sergei V., Ondrej Dyck, Stephen Jesse, and Maxim Ziatdinov. "Exploring order parameters and dynamic processes in disordered systems via variational autoencoders." Science Advances 7, no. 17 (April 2021): eabd5084. http://dx.doi.org/10.1126/sciadv.abd5084.
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We suggest and implement an approach for the bottom-up description of systems undergoing large-scale structural changes and chemical transformations from dynamic atomically resolved imaging data, where only partial or uncertain data on atomic positions are available. This approach is predicated on the synergy of two concepts, the parsimony of physical descriptors and general rotational invariance of noncrystalline solids, and is implemented using a rotationally invariant extension of the variational autoencoder applied to semantically segmented atom-resolved data seeking the most effective reduced representation for the system that still contains the maximum amount of original information. This approach allowed us to explore the dynamic evolution of electron beam–induced processes in a silicon-doped graphene system, but it can be also applied for a much broader range of atomic scale and mesoscopic phenomena to introduce the bottom-up order parameters and explore their dynamics with time and in response to external stimuli.
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Hong, H. P., and S. Somo. "Probabilistic assessment of pavement conditions." Canadian Journal of Civil Engineering 28, no. 5 (October 1, 2001): 813–22. http://dx.doi.org/10.1139/l01-035.
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Pavements are subjected to repeated traffic and environmental actions. These actions lead to the degradation of pavement and affect the pavement performance. The assessment of pavement performance is important not only for selecting pavement design parameters but also for choosing pavement maintenance and rehabilitation strategies. The traffic loads, the environmental actions, and the properties of pavement material are uncertain. These uncertainties must be taken into account when predicting the pavement performance. Since the traffic and environmental actions vary with time, they should be modeled as stochastic processes. In this study, stochastic models of the net traffic load growth and environmental actions are proposed based on the rectangular pulse processes. These models can be used in conjunction with the Ontario Pavement Analysis of Cost (OPAC) model to predict flexible pavement performance in a probabilistic framework. The prediction of pavement performance for a typical pavement was carried out by using the simple simulation technique and the first-order reliability method. The analysis results suggest that the predicted pavement serviceability measured in terms of the riding comfort index depends on the correlation between traffic effects in each year and the correlation between the environmental actions in each year. The results also suggest that the uncertainty in the riding comfort index is controlled by the uncertainty in traffic and environmental actions in the early stage of service, while it is dominated by the material property of the subgrade in the later stage of service.Key words: deterioration, reliability, pavement, serviceability, stochastic process.
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Turyahikayo, W., FB Matsiko, JJ Okiror, BB Obaa, and JH Hanf. "The perceived role of innovation platforms in addressing the agricultural value chain collective problems: an empirical application of transaction cost theory." International Journal of Agricultural Research, Innovation and Technology 8, no. 2 (December 31, 2018): 1–12. http://dx.doi.org/10.3329/ijarit.v8i2.40550.
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Agricultural innovation platforms are increasingly seen as a panacea for mitigating the agricultural value chain challenges through enabling the co-evolution of different elements in the innovation process. A number of previous studies on IPs show processes for their formation and contribution to innovations. Very few studies have attempted to investigate the perceived benefits from platforms as important determinants for actor participation. Using a sample of 319 randomly selected farmers from one innovation platform in Uganda, it was established that the uncertain markets for the agricultural output, sources of inputs and agricultural information were perceived to be the key motivators for the formation of the platform. The study found a positive significant relationship between transaction cost challenges of environmental uncertainty and structural embeddedness (p<0.01) and frequency of interaction and structural embeddedness (p<0.05). On the other hand, environmental uncertainty, asset specificity and frequency of interactions were significantly correlated with relational embeddedness (p<0.05). However, the complexity of tasks in the value chain was not significantly correlated with structural and relational embeddedness (p≥0.05). It therefore means that to ensure effective participation and implementation of platform activities, efforts ought to be placed on fulfilling the platform’s promise as a forum for mitigation of transaction cost challenges such as inadequate markets for both output and inputs, customized products and inputs and lack of valuable agricultural information.
Int. J. Agril. Res. Innov. & Tech. 8 (2): 1-12, December, 2018
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Liu, Zhe, Wenchang Zhao, Kian K. Sepahvand, Yintao Wei, and Steffen Marburg. "A Three-Dimensional Ring Model for Uncertainty Quantification in Natural Frequencies and Sound Radiation Characteristics of Tires." Journal of Theoretical and Computational Acoustics 28, no. 02 (June 2020): 2050016. http://dx.doi.org/10.1142/s2591728520500164.
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Material and geometrical parameters of tires involve some degree of uncertainty mainly related to production processes. Accordingly, the associated structural responses are affected by these uncertainties. In this study, a novel theoretical ring model is presented to describe the in-plane and out-of-plane vibrations as well as the steady-state response of tires, and then to evaluate the influence of the uncertainties in structural parameters on the natural frequencies and the sound radiation characteristics under uncertain excitations. The Hamilton principle is applied here to derive the governing equations. The modal superposition method is used to calculate the steady-state response of the tire. In the sound radiation analysis, the in-plane and out-of-plane bending and torsional vibrations under a set of harmonic unit forces and moments are treated as the source of noise generation. On this basis, the generalized polynomial chaos expansion method is then adopted to evaluate the influence of the uncertainty on the natural frequencies and the sound power. To obtain the unknown coefficients of the expansions, the nonintrusive probabilistic collocation method is employed. Moreover, considering the concept of linear independence of vectors, the number of collocation points is reduced. It is applied to investigate the impacts of the elastic and structural uncertainties on the natural frequencies of the tire. This yields an efficient simulation in terms of computational costs. Finally, the distributions of the sound power due to the forced vibration under the random concentrated line forces are given.
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Sikorska, A. E., A. Scheidegger, K. Banasik, and J. Rieckermann. "Bayesian uncertainty assessment of flood predictions in ungauged urban basins for conceptual rainfall-runoff models." Hydrology and Earth System Sciences 16, no. 4 (April 12, 2012): 1221–36. http://dx.doi.org/10.5194/hess-16-1221-2012.
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Abstract. Urbanization and the resulting land-use change strongly affect the water cycle and runoff-processes in watersheds. Unfortunately, small urban watersheds, which are most affected by urban sprawl, are mostly ungauged. This makes it intrinsically difficult to assess the consequences of urbanization. Most of all, it is unclear how to reliably assess the predictive uncertainty given the structural deficits of the applied models. In this study, we therefore investigate the uncertainty of flood predictions in ungauged urban basins from structurally uncertain rainfall-runoff models. To this end, we suggest a procedure to explicitly account for input uncertainty and model structure deficits using Bayesian statistics with a continuous-time autoregressive error model. In addition, we propose a concise procedure to derive prior parameter distributions from base data and successfully apply the methodology to an urban catchment in Warsaw, Poland. Based on our results, we are able to demonstrate that the autoregressive error model greatly helps to meet the statistical assumptions and to compute reliable prediction intervals. In our study, we found that predicted peak flows were up to 7 times higher than observations. This was reduced to 5 times with Bayesian updating, using only few discharge measurements. In addition, our analysis suggests that imprecise rainfall information and model structure deficits contribute mostly to the total prediction uncertainty. In the future, flood predictions in ungauged basins will become more important due to ongoing urbanization as well as anthropogenic and climatic changes. Thus, providing reliable measures of uncertainty is crucial to support decision making.
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Kim, Joonyoung, Taewoong Kang, Dongwoon Song, and Seung-Joon Yi. "Design and Control of a Open-Source, Low Cost, 3D Printed Dynamic Quadruped Robot." Applied Sciences 11, no. 9 (April 22, 2021): 3762. http://dx.doi.org/10.3390/app11093762.
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In this paper, we present a new open source dynamic quadruped robot, PADWQ (pronounced pa-dook), which features 12 torque controlled quasi direct drive joints with high control bandwidth, as well as onboard depth sensor and GPU-equipped computer that allows for a highly dynamic locomotion over uncertain terrains. In contrast to other dynamic quadruped robots based on custom actuator and machined metal structural parts, the PADWQ is entirely built from off the shelf components and standard 3D printed plastic structural parts, which allows for a rapid distribution and duplication without the need for advanced machining process. To make sure that the plastic structural parts can withstand the stress of dynamic locomotion, we performed finite element analysis (FEA) on leg structural parts as well as a continuous walking test using the physical robot, both of which the robot has passed successfully. We hope this work to help a wide range of researchers and engineers that need an affordable, highly capable and easily customizable quadruped robot.
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Tahiliani, Jackie, Jeanne Leisk, Kerry Aradhya, Karen Ouyang, Swaroop Aradhya, and Keith Nykamp. "Utility of RNA Sequencing Analysis in the Context of Genetic Testing." Current Genetic Medicine Reports 8, no. 4 (November 12, 2020): 140–46. http://dx.doi.org/10.1007/s40142-020-00195-7.
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Abstract Purpose of Review RNA analysis is beginning to be integrated into clinical laboratory genomics, and a review of its current uses and limitations is warranted. Here, we summarize the scope and utility of RNA analysis in the context of clinical genetic testing, including considerations for genetic counseling. Recent Findings RNA analysis is a powerful approach for interpreting some variants of uncertain significance, for analyzing splicing alterations, for providing additional functional evidence for sequence and structural variants, and for discovering novel variants. However, a review of RNA sequencing methods has noted variability in both laboratory processes and findings. Genetic counseling related to RNA analysis has to take into account nonstandardized laboratory processes, sample-type limitations, and differences in variant-interpretation outcomes. Summary RNA analysis is an important complement to DNA testing, although limitations still exist. Maximizing the utility of RNA analysis will require appropriate patient referrals and standardization of laboratory processes as the practice continues to expand the ability to identify and resolve molecular diagnoses.
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Johnson, Jill S., Leighton A. Regayre, Masaru Yoshioka, Kirsty J. Pringle, Steven T. Turnock, Jo Browse, David M. H. Sexton, et al. "Robust observational constraint of uncertain aerosol processes and emissions in a climate model and the effect on aerosol radiative forcing." Atmospheric Chemistry and Physics 20, no. 15 (August 13, 2020): 9491–524. http://dx.doi.org/10.5194/acp-20-9491-2020.
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Abstract. The effect of observational constraint on the ranges of uncertain physical and chemical process parameters was explored in a global aerosol–climate model. The study uses 1 million variants of the Hadley Centre General Environment Model version 3 (HadGEM3) that sample 26 sources of uncertainty, together with over 9000 monthly aggregated grid-box measurements of aerosol optical depth, PM2.5, particle number concentrations, sulfate and organic mass concentrations. Despite many compensating effects in the model, the procedure constrains the probability distributions of parameters related to secondary organic aerosol, anthropogenic SO2 emissions, residential emissions, sea spray emissions, dry deposition rates of SO2 and aerosols, new particle formation, cloud droplet pH and the diameter of primary combustion particles. Observational constraint rules out nearly 98 % of the model variants. On constraint, the ±1σ (standard deviation) range of global annual mean direct radiative forcing (RFari) is reduced by 33 % to −0.14 to −0.26 W m−2, and the 95 % credible interval (CI) is reduced by 34 % to −0.1 to −0.32 W m−2. For the global annual mean aerosol–cloud radiative forcing, RFaci, the ±1σ range is reduced by 7 % to −1.66 to −2.48 W m−2, and the 95 % CI by 6 % to −1.28 to −2.88 W m−2. The tightness of the constraint is limited by parameter cancellation effects (model equifinality) as well as the large and poorly defined “representativeness error” associated with comparing point measurements with a global model. The constraint could also be narrowed if model structural errors that prevent simultaneous agreement with different measurement types in multiple locations and seasons could be improved. For example, constraints using either sulfate or PM2.5 measurements individually result in RFari±1σ ranges that only just overlap, which shows that emergent constraints based on one measurement type may be overconfident.
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MAGNANI, GIOVANNA, and ANTONELLA ZUCCHELLA. "A model of entrepreneurial internationalisation in uncertain foreign environments: smaller firms and the global niche strategy." Sinergie Italian Journal of Management 38, no. 3 (January 15, 2021): 23–50. http://dx.doi.org/10.7433/s113.2020.03.
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Purpose of the paper: By proposing a model of SMEs’ entry in foreign markets characterised by uncertainty, we test the relationships among the implementation of a global niche strategy, the perception of lower competition, and international performance. Methodology: Hypotheses are tested on a sample of 110 Australian firms by applying structural equation modelling through the PLS-SEM technique. Results: Our results support the idea that entrepreneurial firms need to create their own environment and, at the same time, control it by exerting high levels of control on manufacturing and technological capabilities and by vertically integrating production processes. Research limitations: More samples from more countries would increase the generalisability of the results. The operationalisation of the components of the global niche strategy which resulted as non-significant need further refinement. Longitudinal studies are required to measure the sustainability of the global niche strategy over time. Practical implications: A customer focus instead of a country focus can help manage perceived uncertainty while growing internationally. Furthermore, decision makers should leverage on product uniqueness through a continuous refinement of technology thanks to insourced production processes. Originality of the paper. To date, no study has advanced a model to represent firms’ internationalisation by considering a process that starts with the formation of strategic antecedents - here represented by the components of the global niche strategy - of international performance.
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Junaid, A., S. M. Kren, M. E. Rosenberg, K. A. Nath, and T. H. Hostetter. "Physiological and structural responses to chronic experimental renal allograft injury." American Journal of Physiology-Renal Physiology 267, no. 6 (December 1, 1994): F1102—F1106. http://dx.doi.org/10.1152/ajprenal.1994.267.6.f1102.
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Chronic rejection necessitates a return to dialysis or retransplantation for a significant number of patients with renal allografts. Although alloresponses between donor organ and recipient importantly determine this process, the detailed immunologic processes and organ physiology of chronic rejection are unclear; in consequence its mechanism and therapy are uncertain. A model of chronic rejection in the rat was used to examine several facets of this process. Fisher-to-Lewis (F-L), allogeneic, and Lewis-to-Lewis (L-L), syngeneic, renal transplants were performed in nephrectomized recipients. All rats were treated with cyclosporin A (5 mg.kg-1.day-1) for 10 days from the time of grafting. At 6 wk, allogeneically grafted animals had a higher protein excretion rate (F-L, 47 +/- 30 mg/day; L-L, 17 +/- 6 mg/day; P <0.05) and an increase in glomerular capillary pressure (F-L, 69 +/- 5 mmHg; L-L, 58 +/- 8 mmHg; P <0.05) and fractional cortical interstitial volume (F-L, 29.8 +/- 4.3%; L-L, 19.5 +/- 4.0%; P < 0.01). This model of chronic rejection is characterized by glomerular capillary hypertension, proteinuria, and cortical interstitial expansion. Because these findings are also present in other models of chronic renal injury, mechanisms in addition to alloresponses may operate in chronic rejection.
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Bárbara, Carla Patricia, Patricia Cabello, Alexandre Bouche, Ingrid Aarnes, Carlos Gordillo, Oriol Ferrer, Maria Roma, and Pau Arbués. "Quantifying the impact of the structural uncertainty on the gross rock volume in the Lubina and Montanazo oil fields (Western Mediterranean)." Solid Earth 10, no. 5 (September 27, 2019): 1597–619. http://dx.doi.org/10.5194/se-10-1597-2019.
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Abstract. Structural uncertainty is a key parameter affecting the accuracy of the information contained in static and dynamic reservoir models. However, quantifying and assessing its real impact on reservoir property distribution, in-place volume estimates and dynamic simulation has always been a challenge. Due to the limitation of the existing workflows and time constraints, the exploration of all potential geological configurations matching the interpreted data has been limited to a small number of scenarios, making the future field development decisions uncertain. We present a case study in the Lubina and Montanazo mature oil fields (Western Mediterranean) in which the structural uncertainty in the seismic interpretation of faults and horizons has been captured using modern reservoir modeling workflows. We model the fault and horizon uncertainty by means of two workflows: the manually interpreted and the constant uncertainty cases. In the manually interpreted case, the zones of ambiguity in the position of horizons and faults are defined as locally varying envelopes around the best interpretation, whose dimensions mainly vary according to the frequency content of the seismic data, lateral variations of amplitudes along reflectors, and how the reflectors terminate around faults when fault reflections are not present in the seismic image. In the constant case, the envelope dimensions are kept constant for each horizon and each fault. Both faults and horizons are simulated within their respective uncertainty envelopes as provided to the user. In all simulations, conditioning to available well data is ensured. Stochastic simulation was used to obtain 200 realizations for each uncertainty modeling workflow. The realizations were compared in terms of gross rock volumes above the oil–water contact considering three scenarios at the depths of the contact. The results show that capturing the structural uncertainty in the picking of horizons and faults in seismic data has a relevant impact on the volume estimation. The models predict percentage differences in the mean gross rock volume with respect to best-estimate interpretation up to 7 % higher and 12 % lower (P10 and P90). The manually interpreted uncertainty workflow reports narrower gross rock volume predictions and more consistent results from the simulated structural models than the constant case. This work has also revealed that, for the Lubina and Montanazo fields, the fault uncertainty associated with the major faults that bound the reservoir laterally strongly affects the gross rock volume predicted. The multiple realizations obtained are geologically consistent with the available data, and their differences in geometry and dimensions of the reservoir allow us to improve the understanding of the reservoir structure. The uncertainty modeling workflows applied are easy to design and allow us to update the models when required. This work demonstrates that knowledge of the data and the sources of uncertainty is important to set up the workflows correctly. Further studies can combine other sources of uncertainty in the modeling process to improve the risk assessment.
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Ercan, A., and M. L. Kavvas. "Ensemble Modeling of Hydrologic and Hydraulic Processes at One Shot: Application to Kinematic Open-Channel Flow under Uncertain Channel Properties and Uncertain Lateral Flow Conditions by the Stochastic Method of Characteristics." Journal of Hydrologic Engineering 17, no. 3 (March 2012): 414–23. http://dx.doi.org/10.1061/(asce)he.1943-5584.0000434.
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Kong, Liulin, Heng Li, Bo Zhang, and Hanbin Luo. "Estimation of High Structural Reliability Involving Nonlinear Dependencies Based on Linear Correlations." Advances in Civil Engineering 2021 (August 24, 2021): 1–18. http://dx.doi.org/10.1155/2021/8836330.
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Stochastic nonlinear dependencies have been reported extensively between different uncertain parameters or in their time or spatial variance. However, the description of dependency is commonly not provided except a linear correlation. The structural reliability incorporating nonlinear dependencies thus needs to be addressed based on the linear correlations. This paper first demonstrates the capture of nonlinear dependency by fitting various bivariate non-Gaussian copulas to limited data samples of structural material properties. The vine copula model is used to enable a flexible modeling of multiple nonlinear dependencies by mapping the linear correlations into the non-Gaussian copula parameters. A sequential search strategy is applied to achieve the estimate of numerous copula parameters, and a simplified algorithm is further designed for reliability involving stationary stochastic processes. The subset simulation is then adopted to efficiently generate random variables from the corresponding distribution for high reliability evaluation. Two examples including a frame structure with different stochastic material properties and a cantilever beam with spatially variable stochastic modulus are investigated to discuss the possible effects of nonlinear dependency on structural reliability. Since the dependency can be determined qualitatively from limited data, the proposed method provides a feasible way for reliability evaluation with prescriptions on correlated stochastic parameters.
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Vaidogas, Egidijus Rytas, and Jurgita Šakėnaitė. "Solving the Problem of Multiple-Criteria Building Design Decisions with respect to the Fire Safety of Occupants: An Approach Based on Probabilistic Modelling." Mathematical Problems in Engineering 2015 (2015): 1–18. http://dx.doi.org/10.1155/2015/792658.
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The design of buildings may include a comparison of alternative architectural and structural solutions. They can be developed at different levels of design process. The alternative design solutions are compared and ranked by applying methods of multiple-criteria decision-making (MCDM). Each design is characterised by a number of criteria used in a MCDM problem. The paper discusses how to choose MCDM criteria expressing fire safety related to alternative designs. Probability of a successful evacuation of occupants from a building fire and difference between evacuation time and time to untenable conditions are suggested as the most important criteria related to fire safety. These two criteria are treated as uncertain quantities expressed by probability distributions. Monte Carlo simulation of fire and evacuation processes is natural means for an estimation of these distributions. The presence of uncertain criteria requires applying stochastic MCDM methods for ranking alternative designs. An application of the safety-related criteria is illustrated by an example which analyses three alternative architectural floor plans prepared for a reconstruction of a medical building. A MCDM method based on stochastic simulation is used to solve the example problem.
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Fisher, J. B., M. Sikka, W. C. Oechel, D. N. Huntzinger, J. R. Melton, C. D. Koven, A. Ahlström, et al. "Carbon cycle uncertainty in the Alaskan Arctic." Biogeosciences Discussions 11, no. 2 (February 20, 2014): 2887–932. http://dx.doi.org/10.5194/bgd-11-2887-2014.
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Abstract. Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for Alaska, we provide a baseline of terrestrial carbon cycle structural and parametric uncertainty, defined as the multi-model standard deviation (σ) against the mean (x) for each quantity. Mean annual uncertainty (σ/x) was largest for net ecosystem exchange (NEE) (−0.01± 0.19 kg C m−2 yr−1), then net primary production (NPP) (0.14 ± 0.33 kg C m−2 yr−1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m−2 yr−1), gross primary production (GPP) (0.22 ± 0.50 kg C m−2 yr−1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m−2 yr−1), CH4 flux (2.52 ± 4.02 g CH4 m−2 yr−1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m−2 yr−1), and soil carbon (14.0± 9.2 kg C m−2). The spatial patterns in regional carbon stocks and fluxes varied widely with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Additionally, a feedback (i.e., sensitivity) analysis was conducted of 20th century NEE to CO2 fertilization (β) and climate (γ), which showed that uncertainty in γ was 2x larger than that of β, with neither indicating that the Alaskan Arctic is shifting towards a certain net carbon sink or source. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic.
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Qiao, Lijun, Luo Xiao, Qingsheng Luo, Minghao Li, and Jianfeng Jiang. "Design Hybrid Iterative Learning Controller for Directly Driving the Wheels of Mobile Platform against Uncertain Parameters and Initial Errors." Applied Sciences 11, no. 17 (September 3, 2021): 8181. http://dx.doi.org/10.3390/app11178181.
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In this paper, we develop a hybrid iterative learning controller (HILC) for a non-holonomic wheeled mobile platform to achieve trajectory tracking with actual complex constraints, such as physical constraints, uncertain parameters, and initial errors. Unlike the traditional iterative learning controller (ILC), the control variable selects the rotation speed of two driving wheels instead of the forward speed and the rotation speed. The hybrid controller considers the physical constraints of the robot’s motors and can effectively handle the uncertain parameters and initial errors of the system. Without the initial errors, the hybrid controller can improve the convergence speed for trajectory tracking by adding other types of error signals; otherwise, the hybrid controller achieves trajectory tracking by designing a signal compensation for the initial errors. Then, the effectiveness of the proposed hybrid controller is proven by the relationship between the input, output, and status signals. Finally, the simulations demonstrate that the proposed hybrid iterative learning controller effectively tracked various trajectories by directly controlling the two driving wheels under various constraints. Furthermore, the results show that the controller did not significantly depend on the system’s structural parameters.
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Baek, Jang-Woon, and Su-Min Kang. "Development of Multi-Tee-Type Precast Concrete Slabs with Insulating Materials for Structural Safety at the Construction Stage." Applied Sciences 11, no. 4 (February 13, 2021): 1693. http://dx.doi.org/10.3390/app11041693.
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Multi-tee-type precast concrete (PC) slab systems are widely used for the construction of modular high-load long-span buildings. However, the structural safety of the dapped end is uncertain, owing to the unanchored shear reinforcement at the construction stage. This study proposes the use of clip-type shear reinforcement at the dapped ends of multi-tee PC slabs to secure their structural performance at the construction stage. To investigate the performance of this approach, a monotonic loading test was performed on simply supported PC slabs, considering structural safety at the construction stage. The reinforcement details of the PC slab’s dapped end (with existing Z-type or proposed clip-type shear reinforcement) and the shear-to-span ratio (12.8 or 6.4) were considered as test parameters. The load–deflection relationship, failure mode, strength ratios to the predicted strength, and shear reinforcement strains were analyzed. The results showed that the tested flexural strength ratio of the PC slabs at the construction stage to the design flexural strength was 1.20–1.40. The enclosed shape and diagonal arrangement of the clip-type shear reinforcement enabled sufficient anchorage performance at the dapped end, indicating that clip-type shear reinforcement can be viable for use at the dapped ends of PC slabs under construction loads.
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Dohanich, Gary. "Ovarian Steroids and Cognitive Function." Current Directions in Psychological Science 12, no. 2 (April 2003): 57–61. http://dx.doi.org/10.1111/1467-8721.01226.
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The ovarian steroids, estrogen and progesterone, not only govern reproductive events in mammalian females but also influence an array of other processes. Of particular clinical interest is the potential of ovarian steroids to facilitate storage of new memories and to protect neurons from various threats. Research during the past decade confirms that estrogen and progesterone influence the biochemical, electrical, and structural properties of neurons in brain regions that subserve learning and memory. These mechanisms form the biological foundations for the complex effects of ovarian steroids on cognitive functions in various species, including humans. Despite significant progress in our understanding of the roles of hormonal factors in cognitive function and neuronal survival, the value of hormone replacement as a treatment and deterrent for cognitive impairments associated with age, disease, and injury remains uncertain as we enter the new century.
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Wang, Ming, Neil White, Jim Hanan, Di He, Enli Wang, Bronwen Cribb, Darren J. Kriticos, Dean Paini, and Volker Grimm. "Parameter estimation for functional–structural plant models when data are scarce: using multiple patterns for rejecting unsuitable parameter sets." Annals of Botany 126, no. 4 (January 31, 2020): 559–70. http://dx.doi.org/10.1093/aob/mcaa016.
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Abstract Background and Aims Functional–structural plant (FSP) models provide insights into the complex interactions between plant architecture and underlying developmental mechanisms. However, parameter estimation of FSP models remains challenging. We therefore used pattern-oriented modelling (POM) to test whether parameterization of FSP models can be made more efficient, systematic and powerful. With POM, a set of weak patterns is used to determine uncertain parameter values, instead of measuring them in experiments or observations, which often is infeasible. Methods We used an existing FSP model of avocado (Persea americana ‘Hass’) and tested whether POM parameterization would converge to an existing manual parameterization. The model was run for 10 000 parameter sets and model outputs were compared with verification patterns. Each verification pattern served as a filter for rejecting unrealistic parameter sets. The model was then validated by running it with the surviving parameter sets that passed all filters and then comparing their pooled model outputs with additional validation patterns that were not used for parameterization. Key Results POM calibration led to 22 surviving parameter sets. Within these sets, most individual parameters varied over a large range. One of the resulting sets was similar to the manually parameterized set. Using the entire suite of surviving parameter sets, the model successfully predicted all validation patterns. However, two of the surviving parameter sets could not make the model predict all validation patterns. Conclusions Our findings suggest strong interactions among model parameters and their corresponding processes, respectively. Using all surviving parameter sets takes these interactions into account fully, thereby improving model performance regarding validation and model output uncertainty. We conclude that POM calibration allows FSP models to be developed in a timely manner without having to rely on field or laboratory experiments, or on cumbersome manual parameterization. POM also increases the predictive power of FSP models.
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Exbrayat, J. F., N. R. Viney, J. Seibert, S. Wrede, H. G. Frede, and L. Breuer. "Ensemble modelling of nitrogen fluxes: data fusion for a Swedish meso-scale catchment." Hydrology and Earth System Sciences Discussions 7, no. 4 (August 3, 2010): 5299–334. http://dx.doi.org/10.5194/hessd-7-5299-2010.
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Abstract. Model predictions of biogeochemical fluxes at the landscape scale are highly uncertain, both with respect to stochastic (parameter) and structural uncertainty. In this study 5 different models (LASCAM, LASCAM-S, a self-developed tool, SWAT and HBV-N-D) designed to simulate hydrological fluxes as well as mobilisation and transport of one or several nitrogen species were applied to the mesoscale River Fyris catchment in mid-eastern Sweden. Hydrological calibration against 5 years of recorded daily discharge at two stations gave highly variable results with Nash-Sutcliffe Efficiency (NSE) ranging between 0.48 and 0.83. Using the calibrated hydrological parameter sets, the parameter uncertainty linked to the nitrogen parameters was explored in order to cover the range of possible predictions of exported loads for 3 nitrogen species: nitrate (NO3), ammonium (NH4) and total nitrogen (Tot-N). For each model and each nitrogen species, predictions were ranked in two different ways according to the performance indicated by two different goodness-of-fit measures: the coefficient of determination R2 and the root mean square error RMSE. A total of 2160 deterministic Single Model Ensembles (SME) was generated using an increasing number of members (from the 2 best to the 10 best single predictions). Finally, the best SME for each model, nitrogen species and discharge station were selected and merged into 330 different Multi-Model Ensembles (MME). The evolution of changes in R2 and RMSE was used as a performance descriptor of the ensemble procedure. In each studied case, numerous ensemble merging schemes were identified which outperformed any of their members. Improvement rates were generally higher when worse members were introduced. The highest improvements were achieved for the nitrogen SMEs compiled with multiple linear regression models with R2 selected members, which resulted in the RMSE decreasing by up to 90%.
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Lipman, Timothy E., and Daniel Sperling. "Forecasting Cost Path of Electric Vehicle Drive System: Monte Carlo Experience Curve Simulation." Transportation Research Record: Journal of the Transportation Research Board 1587, no. 1 (January 1997): 19–26. http://dx.doi.org/10.3141/1587-03.
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The future costs of electric-drive vehicles, like those of any new technology, are uncertain. One method for forecasting cost reductions uses the concept of the experience curve. Experience curves take into account scale economies, technological improvements in production processes, improvements in product design, and improved efficiency of workers and production management. The future manufacturing cost of an innovative new technology—the synchronous, brushless permanent magnet electric vehicle drivetrain—is analyzed using experience curves and a Monte Carlo simulation technique. Based on experience curve theory and the assumptions used in the analysis, a drop in manufacturing cost is predicted—from today’s $12,000 (with low-volume, hand-built production) to a cost of about $1,200 to $1,700 when full-scale economies and manufacturing experience have been realized. This cost range implies eventual high-volume prices of $1,500 to $2,100 once corporate profit and warranty costs are included. In an ongoing study at the University of California, Davis, experience curve analyses are being integrated with a detailed vehicle cost model to develop short- and long-term cost forecasts for complete electric vehicles.
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Weihaupt, John G., Frans G. Van Der Hoeven, Claude Lorius, and Frederick B. Chambers. "Origin(s) of Antarctica's Wilkes Subglacial Basin." Antarctic Science 26, no. 4 (December 16, 2013): 377–83. http://dx.doi.org/10.1017/s0954102013000746.
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AbstractThe Wilkes Subglacial Basin (WSB), the largest subglacial basin in East Antarctica, is a topographic depression of continental proportions that lies beneath the East Antarctic continental ice sheet. Discovered by the US Victoria Land Traverse 1959–60, the origin of the WSB and the influence of palaeoclimate on its overlying continental ice sheet have remained uncertain since the time of its discovery. Most explanations of origin favour lithospheric structural control as a function of tectonic activity. Lithospheric flexure due to thermally or isostatically induced uplift of the Transantarctic Mountains was suggested in the 1980s. Lithospheric extension and rifting was proposed in the 1990s. More recent investigations have revealed the presence of fold and thrust belts, casting doubt on flexural and extensional hypotheses as the primary mechanisms, suggesting instead a compressional scenario. While remaining inconclusive, these tectonic mechanisms in one form or another, or in combination, are now believed to have provided the structural control for the origin of the WSB. Not yet comprehensively examined, however, is the role of non-tectonic processes in the formation of the WSB, as they may have influenced the size, configuration, subglacial sedimentation and subglacial topography of the WSB. In this paper we review the tectonic hypotheses and examine post-tectonic climate change along with glacial and marine processes as potentially significant factors in the present condition and configuration of the WSB. In the process, we find that there are a number of features not included in previous investigations that may have been major factors in the modification of the subglacial basin.
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Kalińska-Nartiša, Edyta, Christine Thiel, Māris Nartišs, Jan-Pieter Buylaert, and Andrew S. Murray. "Age and sedimentary record of inland eolian sediments in Lithuania, NE European Sand Belt." Quaternary Research 84, no. 1 (July 2015): 82–95. http://dx.doi.org/10.1016/j.yqres.2015.04.001.
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We present a study based on four inland eolian locations in Eastern, Central and Southeastern Lithuania belonging to the northeastern part of the ‘European Sand Belt’ (ESB). Although there have been several previous studies of the ESB, this north-eastern extension has not been investigated before in any detail. The sedimentary structural–textural features are investigated and a chronology was derived using optically stimulated luminescence on both quartz and feldspar. The sedimentary structures and the rounding and surface characteristics of the quartz grains argue for a predominance of eolian transport. Additionally, some structural alternations and a significant contribution of non-eolian grains are interpreted as inherited local glacial/glaciofluvial-bearing lithologies.Three main (glaciolacustrine–) eolian phases are distinguished based on the position in the landscape and the luminescence ages: (1) Anolder eolian seriesaround 15 to 16 ka, possibly correlated with the cold GS-2a event according to the GRIP stratigraphy, and (2) ayounger eolian seriesaround 14.0 ka, possibly representing the GI-1d and 1c events. Theolder eolian seriesis underlain by (3) aglaciolacustrine–eolian seriesfor which the period of deposition remains uncertain due to the significant discrepancy between the ages based on quartz and feldspar.
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Kravitz, Ben, Douglas G. MacMartin, Daniele Visioni, Olivier Boucher, Jason N. S. Cole, Jim Haywood, Andy Jones, et al. "Comparing different generations of idealized solar geoengineering simulations in the Geoengineering Model Intercomparison Project (GeoMIP)." Atmospheric Chemistry and Physics 21, no. 6 (March 19, 2021): 4231–47. http://dx.doi.org/10.5194/acp-21-4231-2021.
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Abstract. Solar geoengineering has been receiving increased attention in recent years as a potential temporary solution to offset global warming. One method of approximating global-scale solar geoengineering in climate models is via solar reduction experiments. Two generations of models in the Geoengineering Model Intercomparison Project (GeoMIP) have now simulated offsetting a quadrupling of the CO2 concentration with solar reduction. This simulation is idealized and designed to elicit large responses in the models. Here, we show that energetics, temperature, and hydrological cycle changes in this experiment are statistically indistinguishable between the two ensembles. Of the variables analyzed here, the only major differences involve highly parameterized and uncertain processes, such as cloud forcing or terrestrial net primary productivity. We conclude that despite numerous structural differences and uncertainties in models over the past two generations of models, including an increase in climate sensitivity in the latest generation of models, the models are consistent in their aggregate climate response to global solar dimming.
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Ovink, Sarah M. "“In Today’s Society, It’s a Necessity”." Social Currents 4, no. 2 (August 20, 2016): 128–45. http://dx.doi.org/10.1177/2329496516663220.
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Latino/a enrollments at U.S. colleges are rapidly increasing. However, Latinos/as remain underrepresented at four-year universities, and college completion rates and household earnings lag other groups’. Yet, little theoretical attention has been paid to the processes that drive these trends, or to what happens when students not traditionally expected to attend college begin to enroll in large numbers. Longitudinal interviews with 50 Latino/a college aspirants in the San Francisco East Bay Area reveal near-universal college enrollment among these mostly low-income youth, despite significant barriers. East Bay Latino/a youth draw on a set of interrelated logics (economic, regional, family/group, college-for-all) supporting their enrollment, because they conclude that higher education is necessary for socioeconomic mobility. In contrast to the predictions of status attainment and rational choice models, these rationally optimistic college aspirants largely ignore known risks, instead focusing on anticipated gains. Given a postrecession environment featuring increasing costs and uncertain employment, this approach led many to enroll in low-cost, less supportive two-year institutions, resulting in long and winding pathways for some. Results suggest that without structural supports, access to college fails to meaningfully redress stratification processes in higher education and the postrecession economy that significantly shape possibilities for mobility.
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Barbalić, Jure, Vlatka Rajčić, Chiara Bedon, and Michal K. Budzik. "Short-Term Analysis of Adhesive Types and Bonding Mistakes on Bonded-in-Rod (BiR) Connections for Timber Structures." Applied Sciences 11, no. 6 (March 17, 2021): 2665. http://dx.doi.org/10.3390/app11062665.
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Bonded-in rods (BiR) represent a structural connection type that is largely used for new timber structures and rehabilitation (repair or reinforcement) of existing structural members. The technology is based on steel / Fiber Reinforced Polymer (FRP) / Glass Fiber Reinforced Polymer (GFRP) rods bonded into predrilled holes in timber elements. The mechanical advantages of BiRs include high local force capacity, improved strength, a relatively high stiffness and the possibility of ductile behaviour. They also offer aesthetic benefits, given that rods are hidden in the cross sections of wooden members. As such, BiR connections are regarded as a solution with great potential, but still uncertain design formulations. Several research projects have dealt with BiRs, but a final definition of their mechanics and a universal design procedure is still missing. This research study explores the typical fracture mechanics modes for BiR connections. A special focus is given to the evaluation of the impact of adhesive bonds under various operational conditions (i.e., moisture content of timber). A total of 84 specimens are tested in pull-out setup, and investigated with the support of digital image correlation (DIC). The reliability of empirical equations and a newly developed analytical model in support of design, based on linear elastic fracture mechanics (LEFM), is also assessed.
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Seleznev, M. N., and A. Yu Vinogradov. "The application of acoustic emission method for ultrasonic fatigue testing monitoring." Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta, no. 2 (2021): 47–56. http://dx.doi.org/10.18323/2073-5073-2021-2-47-56.
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The ultrasonic fatigue testing (USFT) is an effective method for rapid determination of the fatigue properties of structural materials under high cycle (≥106 cycles) loading. However, the occurrence and accumulation of fatigue damage with this test method remain uncertain due to the limitations of the existing measurement methods. Currently used monitoring methods allow detecting the fatigue cracks, but only in the late stages of failure. Despite the superior sensitivity to localized processes in materials, the use of the acoustic emission (AE) method in ultrasonic testing is extremely difficult due to the presence of resonant noise. This work aimed to suppress resonant noise and extract the signal for early detection of fatigue damage. The authors tested the samples of the AlSi9Cu3 aluminum alloy under the asymmetric cyclic loading (R=0.1) at a resonant frequency of 19.5 kHz with a non-threshold AE registration. The fracture surfaces were analyzed by electron and optical microscopy. The authors processed AE by two different methods: (1) the digital filtering method consisted of detecting resonant noise and removing it from the spectrum; (2) the φ-function method consisted of differentiating the spectrogram by time. The processed spectrograms were integrated by the frequency with further extraction of the AE events using the threshold method. The digital filtering method revealed a correlation between AE signals and fatigue damage, whereas the undamaged control sample showed no signals. The φ-function technique demonstrated ambiguous results, showing high AE activity on the control sample.
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Kuikka, S., M. Hildén, H. Gislason, S. Hansson, H. Sparholt, and O. Varis. "Modeling environmentally driven uncertainties in Baltic cod (Gadus morhua) management by Bayesian influence diagrams." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 4 (April 1, 1999): 629–41. http://dx.doi.org/10.1139/f98-206.
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The large variability in Baltic cod (Gadus morhua) recruitment has been attributed both to environmental factors dependent on the inflow of saline water (oxygen and salinity in spawning deeps) and to the size of the spawning stock. Due to the complex interactions between hydrographic and biological processes, future recruitment levels of cod will remain highly uncertain and increase uncertainties in stock predictions and management advice. We assessed the effects of the exploitation level and mesh size used by a trawl fishery on some variables of management interest under different environmental conditions. The modeling consisted of three separate steps: (i) modeling of selectivity, (ii) estimation of uncertainties by Monte Carlo simulations, and (iii) decision analysis by Bayesian influence diagrams, focusing on the structural uncertainties and model selection. Realistic assumptions of environmental conditions and present fishing mortality rates suggest that the current Baltic cod fishery is unsustainable. We use our approach to identify robust management measures that reduce the risk of overfishing and the sensitivity to management information. The value of information analysis demonstrates the advantages of a larger mesh size as a management measure.
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Ercan, A., and M. L. Kavvas. "Ensemble Modeling of Hydrologic and Hydraulic Processes at One Shot: Application to Kinematic Open-Channel Flow under Uncertain Channel Properties by the Stochastic Method of Characteristics." Journal of Hydrologic Engineering 17, no. 1 (January 2012): 168–81. http://dx.doi.org/10.1061/(asce)he.1943-5584.0000425.
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RYAN, EMILY K., MICHAEL J. SOREGHAN, MICHAEL M. MCGLUE, JONATHAN A. TODD, ELLINOR MICHEL, DARRELL S. KAUFMAN, and ISMAEL KIMIREI. "PALEOENVIRONMENTAL IMPLICATIONS OF TIME-AVERAGING AND TAPHONOMIC VARIATION OF SHELL BEDS IN LAKE TANGANYIKA, AFRICA." PALAIOS 35, no. 2 (February 4, 2020): 49–66. http://dx.doi.org/10.2110/palo.2019.037.
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ABSTRACT The lake bottom along structural platforms in Lake Tanganyika, Africa, is carpeted with numerous large shell beds, known to be of late Holocene age, but of uncertain assemblage process. The shell beds may be the result of sedimentological (physical) assembly processes, or biological processes, or both. Previous work focused on the distribution of shell-rich facies, and showed time averaging of the surficial shell bioclasts over the last ∼ 1600 calendar years BP. We focus on an extensive shell deposit along a deltaic platform in Kungwe Bay, Tanzania and examine time-averaging and taphonomy of Neothauma tanganyicense shells to constrain sedimentological and biological processes forming concentrations of shells. New radiocarbon dating indicates that Neothauma shells are time-averaged over the last ∼ 3000 calendar years. Younger shells predominate shallow-water and exhibit unimodal age distributions, while shells from deeper-water exhibit a broader age distribution. Taphonomic results indicate that water depth and distance from the delta river mouth influence shell abrasion and encrustation with more encrustation developing away from sediment input points. Shells with black coatings and reddish-orange oxidation patinas suggest local burial and exposure. The age-frequency distributions of the shells suggest production rates of the shells vary over time and with water depth, tracking climatically driven lake-level changes (e.g., Little Ice Age, ∼ 100–650 BP). In addition, age-distributions suggest that (1) mixing of different populations are more prevalent along the steeper deltaic slopes, and (2) recent decreasing production rates may reflect anthropogenic land-use change and attendant sedimentation, which has implications for Neothauma itself, and for organisms that are obligate occupants of the shell beds. These results suggest both climatic and depositional processes play unique roles in the distribution and accumulation of shell beds in Lake Tanganyika, which informs interpretation of similar paleoenvironments in the geologic record.
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Bredow, R., and M. Kamiński. "Computer Analysis of Dynamic Reliability of Some Concrete Beam Structure Exhibiting Random Damping." International Journal of Applied Mechanics and Engineering 26, no. 1 (January 29, 2021): 45–64. http://dx.doi.org/10.2478/ijame-2021-0003.
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Abstract An efficiency of the generalized tenth order stochastic perturbation technique in determination of the basic probabilistic characteristics of up to the fourth order of dynamic response of Euler-Bernoulli beams with Gaussian uncertain damping is verified in this work. This is done on civil engineering application of a two-bay reinforced concrete beam using the Stochastic Finite Element Method implementation and its contrast with traditional Monte-Carlo simulation based Finite Element Method study and also with the semi-analytical probabilistic approach. The special purpose numerical implementation of the entire Stochastic perturbation-based Finite Element Method has been entirely programmed in computer algebra system MAPLE 2019 using Runge-Kutta-Fehlberg method. Further usage of the proposed technique to analyze stochastic reliability of the given structure subjected to dynamic oscillatory excitation is also included and discussed here because of a complete lack of the additional detailed demands in the current European designing codes.
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Umanet, O. P. "Modern Organization of Financial Control." Accounting. Analysis. Auditing 6, no. 5 (October 27, 2019): 46–57. http://dx.doi.org/10.26794/2408-9303-2019-6-6-46-57.
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The definition of the financial control structural organization in current conditions includes the analysis of functional contents, powers and the structure of relevant controlling institutions. The study of the necessity and obligation of the control function is determined by the essence of management. The main institutions of financial control, their functions and tasks in the established spheres of activity are considered in the same connection with the management. The current processes of economic modernization, innovation, transformation of economic and financial relations into a digital form have led to the expansion of the range and content of the control function. The tendencies of development and improvement of structural and legal basis of financial control are shown in the conditions of digitalization. The features of the control were due to changes in the tasks of control in the conditions of the Russian economy transformation. The role and importance of all forms of control for decisions and the preparation of raw data for them has been proven. The conclusion that there are limitations in the development and improvement of control functions is due to the persistent stereotypes of managers’ behaviour and objective reasons for uncertain prospects and conditions of control. The need for a unified approach to the formation of the organizational, legal and information-methodical framework of financial control is justified. The proposals are designed to help improve the organizational structure of Russia’s financial control institutions while further digitizing its economy.
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He, Y., Q. Zhuang, J. W. Harden, A. D. McGuire, Z. Fan, Y. Liu, and K. P. Wickland. "The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types: a mechanistically based model analysis." Biogeosciences Discussions 11, no. 2 (February 10, 2014): 2227–66. http://dx.doi.org/10.5194/bgd-11-2227-2014.
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Abstract. The large magnitudes of soil carbon stocks provide potentially large feedbacks to climate changes, highlighting the need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer mechanistically based soil decomposition model framework for boreal forest ecosystems. A global sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of SOC pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils; whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil-microbial interactions to better characterize biogeochemical processes in boreal ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.
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Donald, Alice, and Anne-Katrin Speck. "The Dynamics of Domestic Human Rights Implementation: Lessons from Qualitative Research in Europe." Journal of Human Rights Practice 12, no. 1 (February 1, 2020): 48–70. http://dx.doi.org/10.1093/jhuman/huaa007.
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Abstract It is widely acknowledged that the implementation of international human rights judgments is conditioned by domestic factors; yet the means by which judgments exert—or fail to exert—influence on domestic actors and processes is less well understood. This article presents qualitative research undertaken in three European states between 2016 and 2018 to trace the path between selected judgments involving structural or systemic violations and subsequent action by both state and non-state actors. The rich account of the implementation process thereby constructed reveals, in some cases, a direct—and even immediate—causal path between a decision and actions leading to compliance and, in others, a more indirect or uncertain relationship. The article reveals the dynamic and iterative nature of the implementation process, which may at times stall and at other times accelerate and which may be punctuated by extraneous developments that cause the political space for implementation to widen or narrow. It proceeds to examine the strategies employed by actors who either advance or obstruct implementation, and concludes by advocating the formation of the broadest possible compliance ‘partnerships’ in each case, supported by well-functioning domestic structures to coordinate the state’s response.
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Gran-Ruaz, Sophia, Arvind Mani, and Sherry O’Quinn. "An overview of biosimilars and non-biologic complex drugs in Europe, the United States, and Canada and their relevance to multiple sclerosis." Multiple Sclerosis Journal 23, no. 14 (November 2, 2017): 1824–29. http://dx.doi.org/10.1177/1352458517739976.
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The advent of biological medicines has significantly transformed the landscapes of many disease spaces and improved the lives of millions around the world. However, the structural complexity and sensitivity of such products result in a high price tag, adding to already financially strained healthcare systems. As these and other expensive complex drugs lose market exclusivity, stakeholders eagerly await the arrival of lower cost alternatives, such as biosimilars and subsequent entry non-biological complex drugs (NBCDs). Nevertheless, stakeholders remain uncertain about key issues which have resulted in heterogeneous reimbursement policies and varying levels of biosimilar uptake and subsequent entry NBCD approval processes between different markets. With the imminent introduction of both subsequent entry NBCDs and biosimilars for multiple sclerosis (MS), it is important to get a better understanding of this new class of products and how healthcare systems have been adapting to their use. This article defines biosimilars and subsequent entry NBCDs and provides an overview of how these products have been introduced in Europe, the United States, and Canada from a regulatory, health technology, and reimbursement perspective. In addition, this article briefly explores the potential impact and outlook of biosimilar and NBCD products related to MS.
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Liang, Yunping, and Baabak Ashuri. "Option Value of Contingent Finance Support in Transportation Public–Private Partnership Projects." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 7 (June 12, 2020): 555–65. http://dx.doi.org/10.1177/0361198120923668.
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Uncertainties about construction cost and operational revenues are two major risks in transportation public–private partnership (P3) projects. These uncertainties put projects at risk of being unable to fulfill annual debt repayment obligations. When a project generates insufficient cash flow to service the debt in a certain year, it normally has to go for short-term financing by borrowing short-term loans. With the help of revenue risk-sharing mechanisms, supported projects may be able to get rid of unexpected interest disbursement. The objectives of this paper are twofold: ( 1 ) evaluate the refinancing cost of P3 highway projects caused by cash flow shortage; and ( 2 ) critically examine the option value of contingent finance support and compare it with the option value of minimum revenue guarantee on saving refinancing cost for debt repayment. An integrated real options valuation model is created that utilizes utility method for pricing the technical project risk (e.g., construction cost overruns), and utilizes a risk-neutral option pricing method for pricing the market risk (e.g., future traffic). The proposed model has good transferability in relation to involving various risk factors, no matter technical risks or market risks, random variables or random processes. The proposed model helps stakeholders better understand and measure the burden of assuring annual debt repayment under uncertain cash flow. The stakeholders can use the proposed model to evaluate the value of the revenue risk-sharing mechanisms on reducing refinancing cost.
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He, Y., Q. Zhuang, J. W. Harden, A. D. McGuire, Z. Fan, Y. Liu, and K. P. Wickland. "The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types of boreal forest ecosystems: a mechanistically based model analysis." Biogeosciences 11, no. 16 (August 25, 2014): 4477–91. http://dx.doi.org/10.5194/bg-11-4477-2014.
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Abstract. The large amount of soil carbon in boreal forest ecosystems has the potential to influence the climate system if released in large quantities in response to warming. Thus, there is a need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer microbial explicit soil decomposition model framework for boreal forest ecosystems. A thorough sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of soil organic carbon (SOC) pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils, whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil–microbial interactions to better characterize biogeochemical processes in boreal forest ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.
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Freedman, Joshua. "The Recognition Dilemma: Negotiating Identity in the Israeli–Palestinian Conflict." International Studies Quarterly 65, no. 1 (January 8, 2021): 122–35. http://dx.doi.org/10.1093/isq/sqaa091.
Full textAbstract:
Abstract During five years of US-sponsored Israeli–Palestinian peace talks (2009–2014), Israeli PM Netanyahu repeatedly demanded that Palestinians recognize Israel as a Jewish state as part of any final status agreement. Simultaneously, a chorus of Israeli political and military elites consistently challenged this negotiating posture as a threat to the state's very identity. What explains these competing positions on recognition's absence and necessity? Considerable attention in IR has recently focused on the lengths states go to correct acts of misrecognition, out of a genuine need for recognition, and the self-certainty recognition provides in a socially uncertain world. This structural and intrinsic model neglects, however, the powerful role agents can play in constructing, or avoiding, recognition conflict. Political considerations can cause recognition, and its absence, to matter more than it otherwise should, just as they can cause others to view recognition campaigns as vulnerable and ontologically harmful pursuits. This article proposes both an instrumental model of recognition and a theory on the recognition dilemma needed to explain these competing attitudes. In doing so, it shifts attention away from social structure, and relations, in order to take domestic processes seriously as a forum for both the construction and contestation of recognition politics.
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Xiao, Bin, Yu-long Zhou, Chao Gao, Shuang-Xia Shi, Ze-Xi Sun, Zong-biao Song, and Evgeny Petrov. "Vibration Analysis of Driving-Point System with Uncertainties Using Polynomial Chaos Expansion." Shock and Vibration 2020 (September 28, 2020): 1–14. http://dx.doi.org/10.1155/2020/8074351.
Full textAbstract:
A vibration transfer analysis method based on polynomial chaos expansion (PCE) is proposed in this study and is used to analyze the stochastic dynamic compliance of uncertain systems with the Gaussian distribution. The random dynamic compliance is established by utilizing mode superposition on the system as the parameters of system uncertainties are regarded as input variables. Considering the asymptotic probability density function of mode shape, the dynamic compliance is decomposed into the mean of mode shape and the subsystem represented as an orthogonal polynomial expansion. Following this, the vibration transmission analysis approach is proposed for the random vibration. Results of a numerical simulation carried out employing the PCE approach show that broad-band spectrum analysis is more effective than narrow-band spectrum analysis because the former jump of the dynamic compliance amplitude is weakened. This proposed approach is valid and feasible, but since broad-band spectrum analysis loses some important information about the random vibration, both the aforementioned processes need to simultaneously be applied to analyze the random vibration transmission of low-medium frequency systems.
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Zhang, Tao, Minghua Zhang, Wuyin Lin, Yanluan Lin, Wei Xue, Haiyang Yu, Juanxiong He, et al. "Automatic tuning of the Community Atmospheric Model (CAM5) by using short-term hindcasts with an improved downhill simplex optimization method." Geoscientific Model Development 11, no. 12 (December 21, 2018): 5189–201. http://dx.doi.org/10.5194/gmd-11-5189-2018.
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Abstract. Traditional trial-and-error tuning of uncertain parameters in global atmospheric general circulation models (GCMs) is time consuming and subjective. This study explores the feasibility of automatic optimization of GCM parameters for fast physics by using short-term hindcasts. An automatic workflow is described and applied to the Community Atmospheric Model (CAM5) to optimize several parameters in its cloud and convective parameterizations. We show that the auto-optimization leads to 10 % reduction of the overall bias in CAM5, which is already a well-calibrated model, based on a predefined metric that includes precipitation, temperature, humidity, and longwave/shortwave cloud forcing. The computational cost of the entire optimization procedure is about equivalent to a single 12-year atmospheric model simulation. The tuning reduces the large underestimation in the CAM5 longwave cloud forcing by decreasing the threshold relative humidity and the sedimentation velocity of ice crystals in the cloud schemes; it reduces the overestimation of precipitation by increasing the adjustment time in the convection scheme. The physical processes behind the tuned model performance for each targeted field are discussed. Limitations of the automatic tuning are described, including the slight deterioration in some targeted fields that reflect the structural errors of the model. It is pointed out that automatic tuning can be a viable supplement to process-oriented model evaluations and improvement.