Academic literature on the topic 'Structure analysis – Prognostic spatial modelling'
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Journal articles on the topic "Structure analysis – Prognostic spatial modelling"
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Ponzano, Matteo, Bruno Joly, Laurent Descamps, and Philippe Arbogast. "Systematic error analysis of heavy-precipitation-event prediction using a 30-year hindcast dataset." Natural Hazards and Earth System Sciences 20, no. 5 (May 20, 2020): 1369–89. http://dx.doi.org/10.5194/nhess-20-1369-2020.
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Abstract. The western Mediterranean region is prone to devastating flash floods induced by heavy-precipitation events (HPEs), which are responsible for considerable human and material losses. Quantitative precipitation forecasts have improved dramatically in recent years to produce realistic accumulated rainfall estimations. Nevertheless, there are still challenging issues which must be resolved to reduce uncertainties in the initial condition assimilation and the modelling of physical processes. In this study, we analyse the HPE forecasting ability of the multi-physics-based ensemble model Prévision d’Ensemble ARPEGE (PEARP) operational at Météo-France. The analysis is based on 30-year (1981–2010) ensemble hindcasts which implement the same 10 physical parameterizations, one per member, run every 4 d. Over the same period a 24 h precipitation dataset is used as the reference for the verification procedure. Furthermore, regional classification is performed in order to investigate the local variation in spatial properties and intensities of rainfall fields, with a particular focus on HPEs. As grid-point verification tends to be perturbed by the double penalty issue, we focus on rainfall spatial pattern verification thanks to the feature-based quality measure of structure, amplitude, and location (SAL) that is performed on the model forecast and reference rainfall fields. The length of the dataset allows us to subsample scores for very intense rainfall at a regional scale and still obtain a significant analysis, demonstrating that such a procedure is consistent to study model behaviour in HPE forecasting. In the case of PEARP, we show that the amplitude and structure of the rainfall patterns are basically driven by the deep-convection parametrization. Between the two main deep-convection schemes used in PEARP, we qualify that the Prognostic Condensates Microphysics and Transport (PCMT) parametrization scheme performs better than the B85 scheme. A further analysis of spatial features of the rainfall objects to which the SAL metric pertains shows the predominance of large objects in the verification measure. It is for the most extreme events that the model has the best representation of the distribution of object-integrated rain.
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Pritchard, David M. W., Nathan Forsythe, Greg O'Donnell, Hayley J. Fowler, and Nick Rutter. "Multi-physics ensemble snow modelling in the western Himalaya." Cryosphere 14, no. 4 (April 14, 2020): 1225–44. http://dx.doi.org/10.5194/tc-14-1225-2020.
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Abstract. Combining multiple data sources with multi-physics simulation frameworks offers new potential to extend snow model inter-comparison efforts to the Himalaya. As such, this study evaluates the sensitivity of simulated regional snow cover and runoff dynamics to different snowpack process representations. The evaluation is based on a spatially distributed version of the Factorial Snowpack Model (FSM) set up for the Astore catchment in the upper Indus basin. The FSM multi-physics model was driven by climate fields from the High Asia Refined Analysis (HAR) dynamical downscaling product. Ensemble performance was evaluated primarily using MODIS remote sensing of snow-covered area, albedo and land surface temperature. In line with previous snow model inter-comparisons, no single FSM configuration performs best in all of the years simulated. However, the results demonstrate that performance variation in this case is at least partly related to inaccuracies in the sequencing of inter-annual variation in HAR climate inputs, not just FSM model limitations. Ensemble spread is dominated by interactions between parameterisations of albedo, snowpack hydrology and atmospheric stability effects on turbulent heat fluxes. The resulting ensemble structure is similar in different years, which leads to systematic divergence in ablation and mass balance at high elevations. While ensemble spread and errors are notably lower when viewed as anomalies, FSM configurations show important differences in their absolute sensitivity to climate variation. Comparison with observations suggests that a subset of the ensemble should be retained for climate change projections, namely those members including prognostic albedo and liquid water retention, refreezing and drainage processes.
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Barbu, A. L., J. C. Calvet, J. F. Mahfouf, and S. Lafont. "Integrating ASCAT surface soil moisture and GEOV1 leaf area index into the SURFEX modelling platform: a land data assimilation application over France." Hydrology and Earth System Sciences Discussions 10, no. 7 (July 11, 2013): 9057–103. http://dx.doi.org/10.5194/hessd-10-9057-2013.
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Abstract. The land monitoring service of the European Copernicus programme has developed a set of satellite-based biogeophysical products, including surface soil moisture (SSM) and leaf area index (LAI). This study investigates the impact of joint assimilation of remotely sensed SSM derived from ASCAT backscatter data and the GEOV1 satellite-based LAI into the ISBA-A-gs land surface model within the SURFEX modelling platform of Meteo-France. The ASCAT data were bias corrected with respect to the model climatology by using a seasonal-based CDF (Cumulative Distribution Function) matching technique. A multivariate multi-scale land data assimilation system (LDAS) based on the Extended Kalman Filter (EKF) is used for monitoring the soil moisture, terrestrial vegetation, surface carbon and energy fluxes across the France domain at a spatial resolution of 8 km. Each model grid box is divided in a number of land covers, each having its own set of prognostic variables. The filter algorithm is designed to provide a distinct analysis for each land cover while using one observation per grid box. The updated values are aggregated by computing a weighted average. In this study, it is demonstrated that the assimilation scheme works effectively within the ISBA-A-gs model over a four-year period (2008–2011). The EKF is able to extract useful information from the data signal at the grid scale and to distribute the root-zone soil moisture and LAI increments among the mosaic structure of the model. The impact of the assimilation on the vegetation phenology and on the water and carbon fluxes varies from one season to another. The spring drought of 2011 is an interesting case study showing the potential of the assimilation to improve drought monitoring. A comparison between simulated and in situ soil moisture gathered at the twelve SMOSMANIA stations shows improved anomaly correlations for eight stations.
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Barbu, A. L., J. C. Calvet, J. F. Mahfouf, and S. Lafont. "Integrating ASCAT surface soil moisture and GEOV1 leaf area index into the SURFEX modelling platform: a land data assimilation application over France." Hydrology and Earth System Sciences 18, no. 1 (January 14, 2014): 173–92. http://dx.doi.org/10.5194/hess-18-173-2014.
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Abstract. The land monitoring service of the European Copernicus programme has developed a set of satellite-based biogeophysical products, including surface soil moisture (SSM) and leaf area index (LAI). This study investigates the impact of joint assimilation of remotely sensed SSM derived from Advanced Scatterometer (ASCAT) backscatter data and the Copernicus Global Land GEOV1 satellite-based LAI product into the the vegetation growth version of the Interactions between Soil Biosphere Atmosphere (ISBA-A-gs) land surface model within the the externalised surface model (SURFEX) modelling platform of Météo-France. The ASCAT data were bias corrected with respect to the model climatology by using a seasonal-based CDF (Cumulative Distribution Function) matching technique. A multivariate multi-scale land data assimilation system (LDAS) based on the extended Kalman Filter (EKF) is used for monitoring the soil moisture, terrestrial vegetation, surface carbon and energy fluxes across the domain of France at a spatial resolution of 8 km. Each model grid box is divided into a number of land covers, each having its own set of prognostic variables. The filter algorithm is designed to provide a distinct analysis for each land cover while using one observation per grid box. The updated values are aggregated by computing a weighted average. In this study, it is demonstrated that the assimilation scheme works effectively within the ISBA-A-gs model over a four-year period (2008–2011). The EKF is able to extract useful information from the data signal at the grid scale and distribute the root-zone soil moisture and LAI increments throughout the mosaic structure of the model. The impact of the assimilation on the vegetation phenology and on the water and carbon fluxes varies from one season to another. The spring drought of 2011 is an interesting case study of the potential of the assimilation to improve drought monitoring. A comparison between simulated and in situ soil moisture gathered at the twelve SMOSMANIA (Soil Moisture Observing System–Meteorological Automatic Network Integrated Application) stations shows improved anomaly correlations for eight stations.
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Zhu, Wenyue, Jae Yee Ku, Yalin Zheng, Paul C. Knox, Ruwanthi Kolamunnage-Dona, and Gabriela Czanner. "Spatial Linear Mixed Effects Modelling for OCT Images: SLME Model." Journal of Imaging 6, no. 6 (June 5, 2020): 44. http://dx.doi.org/10.3390/jimaging6060044.
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Much recent research focuses on how to make disease detection more accurate as well as “slimmer”, i.e., allowing analysis with smaller datasets. Explanatory models are a hot research topic because they explain how the data are generated. We propose a spatial explanatory modelling approach that combines Optical Coherence Tomography (OCT) retinal imaging data with clinical information. Our model consists of a spatial linear mixed effects inference framework, which innovatively models the spatial topography of key information via mixed effects and spatial error structures, thus effectively modelling the shape of the thickness map. We show that our spatial linear mixed effects (SLME) model outperforms traditional analysis-of-variance approaches in the analysis of Heidelberg OCT retinal thickness data from a prospective observational study, involving 300 participants with diabetes and 50 age-matched controls. Our SLME model has a higher power for detecting the difference between disease groups, and it shows where the shape of retinal thickness profiles differs between the eyes of participants with diabetes and the eyes of healthy controls. In simulated data, the SLME model demonstrates how incorporating spatial correlations can increase the accuracy of the statistical inferences. This model is crucial in the understanding of the progression of retinal thickness changes in diabetic maculopathy to aid clinicians for early planning of effective treatment. It can be extended to disease monitoring and prognosis in other diseases and with other imaging technologies.
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Bennett, R. J., and R. P. Haining. "Spatial Structure and Spatial Interaction: Modelling Approaches to the Statistical Analysis of Geographical Data." Journal of the Royal Statistical Society. Series A (General) 148, no. 1 (1985): 1. http://dx.doi.org/10.2307/2981508.
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Soulié, M., P. Montes, and V. Silvestri. "Modelling spatial variability of soil parameters." Canadian Geotechnical Journal 27, no. 5 (October 1, 1990): 617–30. http://dx.doi.org/10.1139/t90-076.
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The purpose of this study is to show that geostatistics can help in finding the structure of the spatial variability of the undrained shear strength within a clay deposit. The site under study, B-6, owes its name to the earth dam that will be constructed on it; the site is located on the shore of the Broadback River in the James Bay area of Quebec. The geostatistical analysis is carried out on the unaltered zone of the B-6 clay; it shows an anisotropic structure for the spatial variability. The knowledge of the structure (variogram) of the undrained shear strength is used in the kriging theory to compute estimations at points of the deposit where experimental measurements are not available. Kriging is also used to identify weak zones within the B-6 clay. The geostatistical analysis of the B-6 clay gives the opportunity to test the capability of the method. Even if the errors of measurements were small, the variogram has permitted detection and correction of a bias that affected a certain number of vane profiles. Key words: clay, geostatistics, undrained shear strength, variogram, measurements errors, kriging.
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Zimeras, Stelios, and Yiannis Matsinos. "Spatial Uncertainty Analysis in Ecological Biology." International Journal of Systems Biology and Biomedical Technologies 2, no. 1 (January 2013): 14–24. http://dx.doi.org/10.4018/ijsbbt.2013010102.
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Uncertainty analysis is the part of risk analysis that focuses on the uncertainties in the data characteristics. Important components of uncertainty analysis include qualitative analysis that identifies the uncertainties, quantitative analysis of the effects of the uncertainties on the decision process, and communication of the uncertainty. (Funtowwicz & Ravetz 1990; Petersen, 2000; Regan et a1., 2002; Katz 2002). The analyses include simple descriptive procedures till quantitative estimation of uncertainty, and decision-based procedures. The analysis may be qualitative or quantitative, depending on the stage of analysis required and the amount of information available. When a neighbourhood structure lattice system is applied, a spatial connectivity between regions is defined where investigation of that structure includes modelling of the spatial homogeneity is introduced. Spatial investigation involves stochastic modelling especially in cases where the incomplete data involves hide information’s. In this work a spatial analysis methodology was introduced and procedures to solve the problem with spatial variability are described.
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Chen, Xia, and Jianmin Liu. "Fiscal Decentralization and Environmental Pollution: A Spatial Analysis." Discrete Dynamics in Nature and Society 2020 (March 26, 2020): 1–10. http://dx.doi.org/10.1155/2020/9254150.
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Based on annual data over the period 2003 to 2017 covering 31 provinces in China, the environmental pollution index and environmental regulation index are constructed. Moran’s I, the widely used spatial autocorrelation index, is used to analyze the spatial distribution of environmental pollution, which provides a fairly high stability of the positive spatial correlation of environmental pollution. Then, the 0-1 matrix, distance weighting matrix, and economic distance mixed matrix are carried out to weigh space separately. To analyze the impact of fiscal decentralization on environmental pollution, the spatial Durbin model is employed. In the meanwhile, fiscal decentralization is measured from the perspective of both fiscal expenditure decentralization and fiscal revenue decentralization. The results show that the impact of fiscal decentralization on environmental pollution is positive and appears the phenomenon of “race to bottom.” To improve environmental quality, appropriate environmental regulation target, implementing green GDP accounting, and adjusting economic structure should be adopted.
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Yakimov, Basil N., Dmitry I. Iudin, Leonid A. Solntsev, and David B. Gelashvili. "Multifractal analysis of neutral community spatial structure." Journal of Theoretical Biology 343 (February 2014): 44–53. http://dx.doi.org/10.1016/j.jtbi.2013.10.011.
Full textDissertations / Theses on the topic "Structure analysis – Prognostic spatial modelling"
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Lévesque, Josée. "Modelling forest structure and health using high-resolution airborne imagery, investigation of spectral unmixing and spatial analysis of radiometric fractions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60963.pdf.
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(9782597), Wayne Boyd. "A protocol for assessing ecosystem rehabilitation success on open cut coal mines." Thesis, 2012. https://figshare.com/articles/thesis/A_protocol_for_assessing_ecosystem_rehabilitation_success_on_open_cut_coal_mines/13464119.
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"This research was aimed at developing a statistically rigorous prognostic success assessment protocol for evaluating ecosystem rehabilitation. The protocol needs to be repeatable, adaptable and simple enough to be easily applied across a diversity of mining operations and sites ... A five class success rating and valuation was developed and the assessment protocol was demonstrated and tested using real mine data, as a case study from the Bowen Basin, Queensland, Australia"--Abstract.
Books on the topic "Structure analysis – Prognostic spatial modelling"
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Geospatial analysis and modelling of urban structure and dynamics. Dordrecht: Springer, 2010.
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Jiang, Bin, and Xiaobai Yao. Geospatial Analysis and Modelling of Urban Structure and Dynamics. Springer Netherlands, 2012.
Find full textBook chapters on the topic "Structure analysis – Prognostic spatial modelling"
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Goswami, Mrinalini, Chaya Ravishankar, Sunil Nautiyal, and Rüdiger Schaldach. "Integrated Landscape Modelling in India: Evaluating the Scope for Micro-Level Spatial Analysis over Temporal Scale." In Tropical Ecosystems: Structure, Functions and Challenges in the Face of Global Change, 289–315. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8249-9_16.
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Ayeni, ’Bola. "Predictive Modelling of Urban Spatial Structure." In Concepts and Techniques in Urban Analysis, 308–55. Routledge, 2017. http://dx.doi.org/10.4324/9781315105352-13.
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Zimeras, S., and Y. Matsinos. "Modelling Spatial Medical Data." In Effective Methods for Modern Healthcare Service Quality and Evaluation, 75–89. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-9961-8.ch004.
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Models are sometimes incomplete, especially in scaling data where other information of large regions needs to be predicted by smaller ones. Uncertainty analysis is the process of assessing uncertainty in modelling or scaling to identify major uncertainty sources, quantify their degree and relative importance, examine their effects on model output under different scenarios, and determine prediction accuracy. Especially for large dimensional data where spatial process in regional investigation are difficult to applied due to incompleteness leading us to spatial heterogeneity and non-linearity of our data. Modelling the uncertainty particular in scaling data starts with a general structure (linear most of the time) that explains as accurate as it is the real data and the model is built through adding variables, which are significant or which aid in prediction (hierarchical modelling). Parameter estimation is an important issue for the evaluation of these proposed models. Statistical techniques based on the spatial modelling could be proposed to overcome the problem of dimensionality and the spatial homogeneity between different grains levels based on the neighbourhood structure of the regions with similar characteristics. Investigation of the neighbourhood structure analysis could be applied using kriging or variogram techniques. In this work, we introduce and analyse methodologies for scaling data under uncertainty where incomplete data can be explained by spatial modelling at different scales. Incomplete data of uncertainties in regions involve spatial homogeneity upon neighbourhood structure between regions. The last could be illustrated by using spatial modelling techniques (like spatial autocorrelation, partition functions, and multilevel models). Parameter estimation of these models could be achieved by using stochastic (spatial hierarchical models, kriging, auto-correlation) methods. Comparison between different models could be achieved by considering statistical measures like log-likelihood ratio test. The best model is the one, which explains better the real data.
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Zharikova, Maryna Vitalievna. "Dynamic Spatial-Distributed Fire Risk Analysis." In Predicting, Monitoring, and Assessing Forest Fire Dangers and Risks, 101–20. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1867-0.ch005.
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The chapter develops a dynamic spatial-distributed model of forest fire risk. The structure of forest fire risk is represented by two interrelated groups of components describing a potential of forest fire and describing valuable objects being under fire influence. The concept of fire risk which contains the probability of forest fire occurrence, its intensity, and effect, is extended using the threat as the additional prognostic spatial-temporal component that has a predictive property and allows forecasting the possibility of losses at any time. The model of fire risk is based on three stages: potential risk, the source of which is described by fire danger; risk of threat of active forest fire which hasn't covered valuable object yet; risk of destruction when the active fire has covered valuable object. Representation of risk as a process based on three stages allows describing the dynamics of risk in real-time systems, getting insight into risk nature, as well as diagnosing the situation in real time.
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Harshvardhan, M., and Pritam Ranjan. "Statistical Modelling and Analysis of the Computer-Simulated Datasets." In Handbook of Research on Cloud Computing and Big Data Applications in IoT, 202–28. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-8407-0.ch011.
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Over the last two decades, the science has come a long way from relying on only physical experiments and observations to experimentation using computer simulators. This chapter focuses on the modelling and analysis of data arising from computer simulators. It turns out that traditional statistical metamodels are often not very useful for analyzing such datasets. For deterministic computer simulators, the realizations of Gaussian process (GP) models are commonly used for fitting a surrogate statistical metamodel of the simulator output. The chapter starts with a quick review of the standard GP-based statistical surrogate model. The chapter also emphasizes on the numerical instability due to near-singularity of the spatial correlation structure in the GP model fitting process. The authors also present a few generalizations of the GP model, reviews methods, and algorithms specifically developed for analyzing big data obtained from computer model runs, and reviews the popular analysis goals of such computer experiments. A few real-life computer simulators are also briefly outlined here.
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Stillwell, John, and Kirk Harland. "Analysing Interaction Data." In Technologies for Migration and Commuting Analysis, 69–88. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-61520-755-8.ch004.
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Large and complex interaction data sets present researchers with analytical challenges and this chapter attempts to identify and illustrate a number of ways to analyse origin-destination flows. Given the impossible task of providing a comprehensive review in such a limited space, certain analytical measures, modelling methods and visualisation techniques have been selected for inclusion, following an introduction to the notation commonly employed to represent interaction variables. Various Census and NHS patient register data sets are used to exemplify interaction measures, beginning with simple net balances and inflow/outflow ratios and moving onto indices of connectivity, inequality and distance moved. The multiplicative component framework is introduced as a particularly useful analytical approach. More sophisticated methods of modelling interaction data using statistical or mathematical calibration techniques are reviewed, examples of log-linear regression and spatial interaction model structure are highlighted in the context of historical calibration and a brief discussion of the use models for future projection is included. Maps that show patterns of geographical movement function as effective illustrative and research tools. Computerized mapping of geographical movement has evolved since the 1970s and 1980s and, in this chapter, we introduce a new method of mapping flows using vectors and illustrate this approach with micro data on pupils travelling to school. The chapter aims to provide a broad introduction to analysis methods for interaction data, many of which are subsequently applied in later chapters of the book.
Conference papers on the topic "Structure analysis – Prognostic spatial modelling"
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Chowdhry, Bhawani Shankar, Neil M. White, Jai Kumar Jeswani, Khalil Dayo, Manorma Rathi, A. H. Siddiqi, M. Brokate, and A. K. Gupta. "Visualization and Analysis of Wireless Sensor Network Data for Smart Civil Structure Applications Based On Spatial Correlation Technique." In MODELLING OF ENGINEERING AND TECHNOLOGICAL PROBLEMS: International Conference on Modelling and Engineering and Technological Problems (ICMETP) and the 9th Biennial National Conference of Indian Society of Industrial and Applied Mathematics (ISIAM). AIP, 2009. http://dx.doi.org/10.1063/1.3183536.
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Shende, Ketan V., and Richard Keltie. "Modelling and Experimental Comparison of Fluid Structure Coupling for Thin Sheet Metal Tanks Using Statistical Energy Analysis." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59071.
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Acoustic response of flat surfaces in contact with a fluid volume is of some interest for the design of automotive fuel tanks, fluid containers and underwater applications [1]. As this response can be related to the surface vibration response in the linear domain, the effect of fluid structure coupling on the vibration response of the structure is studied in this paper. Advances in the computational abilities have increased the focus of analysis-led approaches in the design of thin sheet metal tanks. Conventional finite element (FE) based approaches are useful at low frequencies but are highly sensitive to geometrical details and local effects at higher frequencies. With changing input parameters, finite element approaches could prove to be computationally expensive during the initial design phase of such structures. Statistical Energy Analysis (SEA) is an energy based approach and was used to study the fluid structure coupling effect on the vibration characteristics of a simple rectangular parallelepiped thin sheet metal tank. A thin steel tank (thickness/min. characteristic dimension <0.01) was excited by a broad band uniform power spectral density white noise signal and the spatial and frequency averaged acceleration responses were compared. Some parameters like the damping loss factor and the excitation force were calculated from the experimental measurements and used as input for SEA simulations. Coupling loss factors were calculated from tests and the trend lines were found to be in agreement with the theoretical calculations. The SEA simulation model results were compared with the conventional FE based approach for reference. Variance studies were used to compute the envelope for the SEA simulation response for a 90% confidence interval. The SEA and the test results comparison was quantified by a correlation coefficient which indicated a moderately strong correlation (>0.5) between the SEA and experimental results.
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Kumar, Rahul, Sayan Gupta, and Shaikh Faruque Ali. "Stochastic Modelling and Analysis of Rotating Bladed Discs." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-16212.
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Abstract This study focusses on probabilistic modelling of the bladed disc system and numerical estimation of the distributions of the response quantities of the system. Stochastic finite element model of the system consisting of all the assemblies and the hub is developed and reported. The spatial inhomogeneity of mistuned structures is modelled as non-Gaussian random field. Experimentally, the system parameters can be measured at the specified locations of the bladed disk structure. In this analysis, a synthetic data is generated which represent this measured data set. Further, Nataf transformation is implemented to each component of the data set to get the polynomial chaos expansion framework of the system parameters. Since, the random field of the system parameter is approximated as correlated random variables, Spearman’s rank correlation coefficient is used in this manuscript to obtain that correlation among the random parameters across the domain. The approximated probability density function obtained through the aforementioned methodology is compared with the target probability density function of the parameter using Kullback–Liebler (KL) entropy as a metric. Also, the same KL entropy is used as a metric to check the convergence of polynomial chaos terms in the expansion. Next, the proposed polynomial chaos method is integrated with commercial finite element software to quantify the propagation of randomness associated with system parameters into the response quantities. Subsequently, the statistical processing helps in estimating the probabilistic measure of the required response quantities. The results obtained through the conventional Monte Carlo (MC) simulations have been used as the benchmark to compare the response characteristics obtained through the proposed algorithm.
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Ebna Hai, Bhuiyan Shameem Mahmood, and Markus Bause. "Adaptive Multigrid Methods for Extended Fluid-Structure Interaction (eXFSI) Problem: Part I — Mathematical Modelling." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53265.
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This contribution is the first part of three papers on Adaptive Multigrid Methods for eXtended Fluid-Structure Interaction (eXFSI) Problem, where we introduce a monolithic variational formulation and solution techniques. In a monolithic nonlinear fluid-structure interaction (FSI), the fluid and structure models are formulated in different coordinate systems. This makes the FSI setup of a common variational description difficult and challenging. This article presents the state-of-the-art of recent developments in the finite element approximation of FSI problem based on monolithic variational formulation in the well-established arbitrary Lagrangian Eulerian (ALE) framework. This research will focus on the newly developed mathematical model of a new FSI problem which is called eXtended Fluid-Structure Interaction (eXFSI) problem in ALE framework. This model is used to design an on-live Structural Health Monitoring (SHM) system in order to determine the wave propagation in moving domains and optimum locations for SHM sensors. eXFSI is strongly coupled problem of typical FSI with a wave propagation problem on the fluid-structure interface, where wave propagation problems automatically adopted the boundary conditions from of the typical FSI problem at each time step. The ALE approach provides a simple, but powerful procedure to couple fluid flows with solid deformations by a monolithic solution algorithm. In such a setting, the fluid equations are transformed to a fixed reference configuration via the ALE mapping. The goal of this work is the development of concepts for the efficient numerical solution of eXFSI problem, the analysis of various fluid-mesh motion techniques and comparison of different second-order time-stepping schemes. This work consists of the investigation of different time stepping scheme formulations for a nonlinear FSI problem coupling the acoustic/elastic wave propagation on the fluid-structure interface. Temporal discretization is based on finite differences and is formulated as an one step-θ scheme; from which we can consider the following particular cases: the implicit Euler, Crank-Nicolson, shifted Crank-Nicolson and the Fractional-Step-θ schemes. The nonlinear problem is solved with Newton’s method whereas the spatial discretization is done with a Galerkin finite element scheme. To control computational costs we apply a simplified version of a posteriori error estimation using the dual weighted residual (DWR) method. This method is used for the mesh adaptation during the computation. The implementation is accomplished via the software library package DOpElib and deal.II for the computation of different eXFSI configurations.
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Luczkowski, Marcin, Steinar Hillersøy Dyvik, John Haddal Mork, and Anders Nils Rønnquist. "Digital workflows vs. spatial structures design." In IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/guimaraes.2019.0563.
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<p>Digital workflows are already widely used by the designers (architects and engineers) in creating a better Building Information Modelling (BIM) data flow. In the core of this design method is a para- metric model, which thanks to open source software can be easily customized according to the pro- ject or user needs. Shell or gridshell structures are very sensitive on the external loads, due to the low weight and big span. The accuracy and reliability are therefore a crucial point in design. More and more architects are using parametrical models, based on visual programing (like Grasshopper or Dynamo) to develop form of spatial structure. The parametric model in shell design gives a high precision in creating BIM model and is the starting point for the structural analysis. In this paper we will present a design method, in which the parametric model is not only the starting point for struc- tural analysis. Thanks to a well-established digital workflow it can occur, that structural analysis is made simultaneously with architectural form finding of the shell. The digital workflow, developed by our research group is based on the Finite Element Method (FEM). The design methodology is to create two kind of structural analyses. The first one, called global, is using beam elements to inves- tigate the general forces and deformations. The second one, called local, is using solid/volume ele- ments to investigate the connection solution. Thanks to fast information transfer between this two analysis and automation of this process, the architect can achieve information about feasibility of the whole designed structure in real time. To validate our approach the timber gridshell was de- signed. The structure with nontrivial shape and customized each of the 61 nodes, was build in 2016 in Trondheim. The nodes were manufactured with usage of the 3D printing technology.</p>
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Major, Mark David, Heba O. Tannous, Sarah Al-Thani, Mahnoor Hasan, Adiba Khan, and Adele Salaheldin. "Macro and micro scale modelling of multi-modal transportation spatial networks in the city-state of Doha, Qatar." In Post-Oil City Planning for Urban Green Deals Virtual Congress. ISOCARP, 2020. http://dx.doi.org/10.47472/piqu7255.
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Researchers and practitioners have been modeling the street networks of metropolitan and geographical regions using space syntax or configurational analysis since the late 1990s and early 2000s. Some models even extend to a national scale. A few examples include the island of Great Britain, within the national boundaries of England, over half of the Combined Statistical Area of Metropolitan Chicago and the entirety of Chatham County, Georgia and the City of Savannah in the USA, and the Chiang-rai Special Economic Zone in northern Thailand bordering Myanmar and Laos. Researchers at Qatar University constructed a space syntax model of Metropolitan Doha in 2018. It covered a land area of 650 km2 , encompassing over 24,000 streets, and approximately eighty-five percent (~85%) of the total population (~2.8 million) in Qatar. In a short time, this model led to a deeper understanding of spatial structure at the metropolitan and neighborhood level in Doha compared to other cities of the world, especially in the Gulf Cooperation Council region. The paper presents the initial results of expanding this model to the State of Qatar, which provides ideal conditions for this type of large-scale modeling using space syntax. It occupies the Qatari Peninsula on the Arabian Peninsula adjacent to the Arabian/Persian Gulf, offering natural boundaries on three sides. Qatar also shares only a single border with another country to the southwest, which Saudi Arabia closed due to the current diplomatic blockade. The expanded model includes all settlements and outlying regions such as Al Ruwais and Fuwayriţ in the far north, Al Khor and the Industrial City of Ras Laffan in the northeast, and Durkan and Zekreet in the west. Space syntax is serving as the analytical basis for research into the effect of the newly opened rail transportation systems on Doha's urban street network. Researchers are also utilizing space syntax to study micro-scale spatial networks for pedestrians in Souq Waqif, Souq Wakra, and other Doha neighborhoods. The paper gives a brief overview of this research's current state with an emphasis on urban studies.
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Gasmi, Rami, and Marc Cahay. "Flare Structure Heat-Up During Depressurization." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78718.
Full textAbstract:
Despite regulations becoming more and more stringent, significant quantities of gas are still flared around the world every year. Indeed, for safety reasons, flaring remains a usual practice in oil and gas production in cases of process upset. For instance, emergency shutdown, when the unit must be depressurized in a short period of time, most of the gas inventories are flared to limit as much as possible the potential consequences of fire and explosion within the facility. With the increase of the global demand for energy and especially in Liquefied Natural Gas (LNG), the recent development of Floating Liquefied Natural Gas unit (FLNG) has raised new challenges concerning flare stack design. Since FLNG facilities handle large flammable gas quantities the flare stack needs to be designed considering much more stringent cases. It results in an increased length of flare stack, to reduce the radiation effects on personnel and equipment. The thermal response of the flare structure needs also to be accounted for in the design, in addition to other load cases such as piping and structural weight or vessel accelerations. To accomplish the structural design of the flare stack, the engineers will have to convert the radiative heat fluxes from the flame into the resulting temperature of the structure exposed. Indeed, temperature is the parameter that can be used as a thermal load case in any finite element analysis calculation code. Current temperature mapping methodologies applied on projects are not exhaustive and are often based on a simplified approach which is now challenged by operators and certification bodies who require more detailed verifications on flare structure heating during continuous or emergency flaring. Moreover, such simplified modelling approaches tends to overestimate thermal protection to mitigate the heat radiation impact. The proposed approach described in this paper will address these points through a multidisciplinary workflow to form a flexible, simple and robust technical methodology to be applied during project execution. The proposed approach will assess heat radiation and temperature calculations in a spatial-temporal reference including the dynamic response. This transient approach is more attractive as computed temperatures will be lower than steady-state approach results which are the usual engineering practice, especially for accidental loading cases, such as emergency depressurization, where the flare release can decrease quickly.
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Wu, Huixuan, Rinaldo L. Miorini, and Joseph Katz. "Analysis of Turbulence in the Tip Region of a Waterjet Pump Rotor." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30791.
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A series of high resolution planar particle image velocimetry measurements performed in a waterjet pump rotor reveal the inner structure of the tip leakage vortex (TLV) which dominates the entire flow field in the tip region. Turbulence generated by interactions among the TLV, the shear layer that develops as the backward leakage flow emerges from the tip clearance as a “wall jet”, the passage flow, and the endwall is highly inhomogeneous and anisotropic. We examine this turbulence in both RANS and LES modelling contexts. Spatially non-uniform distributions of Reynolds stress components are explained in terms of the local mean strain field and associated turbulence production. Characteristic length scales are also inferred from spectral analysis. Spatial filtering of instantaneous data enables the calculation of subgrid scale (SGS) stresses, along with the SGS energy flux (dissipation). The data show that the SGS energy flux differs from the turbulence production rate both in trends and magnitude. The latter is dominated by energy flux from the mean flow to the large scale turbulence, which is resolved in LES, whereas the former is dominated by energy flux from the mean flow to the SGS turbulence. The SGS dissipation rate is also used for calculating the static and dynamic Smagorinsky coefficients, the latter involving filtering at multiple scales; both vary substantially in the tip region, and neither is equal to values obtained in isotropic turbulence.
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Papoutsakis, Andreas, Sergei Sazhin, Steven Begg, Ionut Danaila, and Francky Luddens. "A new approach to modelling the two way coupling for momentum transfer in a hollow-cone spray." In ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Valencia: Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4671.
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A new approach to modelling the interaction between droplets and the carrier phase is suggested. The new model isapplied to the analysis of a spray injected into a chamber of quiescent air, using an Eulerian-Lagrangian approach. The conservative formulation of the equations for mass, momentum and energy transport is used for the analysis of the carrier phase. The dispersed phase is modelled using the Lagrangian approach with droplets represented by individual parcels.The implementation of the Discontinuous Galerkin method (ForestDG), based on a topological representation of the computational mesh by a hierarchical structure consisting of oct- quad- and binary trees, is used in our analysis. Adaptive mesh refinement (h-refinement) enables us to increase the spatial resolution for the computational mesh in the vicinity of the points of interest such as interfaces, geometrical features, or flow discontinuities. The local increase in the expansion order (p-refinement) at areas of high strain rates or vorticity magnitude results in an increase of the order of the accuracy of discretisation of shear layers and vortices.The initial domain consists of a graph of unitarian-trees representing hexahedral, prismatic and tetrahedral elements. The ancestral elements of the mesh can be split into self-similar elements allowing each tree to grow branches to an arbitrary level of refinement. The connectivity of the elements, their genealogy and their partitioning are described by linked lists of pointers. These are attached to the tree data structure which facilitates the on-the-fly splitting, merging and repartitioning of the computational mesh by rearranging the links of each node of the tree. This enables us to refine the computational mesh in the vicinity of the droplet parcels aiming to accurately resolve the coupling betweenthe two phases.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4671
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Artini, Gianluca, and Daniel Broc. "A Homogenisation Method for a FSI Problem: Application to a Tube Bundle Row." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65737.
Full textAbstract:
A research program is ongoing at CEA in the framework of ASTRID project, for developing and validating tools for the analysis of the mechanical dynamic behaviour of Fast Breeder Reactor (FBR) cores. In this context, Fluid Structure Interaction is a recurring problem, especially in case of tube bundles in nuclear reactor cores or steam generators. The large number of elements makes modelling difficult to perform and any direct numerical simulation at whole core scale unachievable. In order to overcome this limitation, we resort to homogenisation techniques which allow to describe the global dynamic behaviour of the whole fluid-structure system. The purpose of this study is to better understand the effects of the spatial variation of the tube displacement field on the whole bundle dynamics. Thanks to multiple scales, a complete development of the problem is conducted. An analysis of the effects of spatial variations of the long scale displacement field on the tube bundle’s dynamics is led. As a first step we consider the homogenisation of Euler linear equations that gives us the possibility to make a thorough assessment of the problem with the extension to follow to Navier-Stokes equations.