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1

Groundwater potentiality deciphering and sensitivity study using remote sensing technique and fuzzy approach

Gandhi Fenil R., Patel Jayantilal N.

Acta Geophysica

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2022

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Vol. 70, no 1

265--282

EN

Elevating industrialization and urbanization have increased water demand, resulting in a water crisis and plummeting groundwater resources day by day. The present research proposed a model to decipher groundwater potential zones by integrating remote sensing (RS) data with fuzzy logic in an ArcGIS environment. Eleven groundwater potentiality influencing factors have been employed for the study. Each layer was passed through a multicollinearity check, resulting in no collinearity found between the layers. Furthermore, each layer was reclassified, ranked according to their potential to the groundwater occurrence, and assigned fuzzy values. The groundwater potential zones were developed by applying an overlay operation to integrate eleven fuzzy layers. According to the fuzzy value, the Surat district is divided into four potential zones: very poor, poor, moderate, and good. The result shows that 32.21% (1343 km2 ) and 31.63% (1319 km2 ) have good and moderate groundwater potential zones, respectively. Additionally, the map removal sensitivity study illustrated that drainage density, lineament density, and rainfall are more sensitive to potential zones in the study area. The potential zones have been verified by a false matrix, indicating substantial agreement between groundwater levels and potential zones with an overall accuracy of 81.1%. Thus, the integration of RS data and fuzzy-based method is an efficient method for deciphering groundwater potential zones and can be applied anywhere with necessary adjustment.

2

Optimized stochastic methods for sensitivity analysis for large-scale air pollution model

Todorov Venelin, Ostromsky Tzvetan, Dimov Ivan, Georgieva Rayna

Annals of Computer Science and Information Systems

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2021

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Vol. 26

85--88

EN

Environmental security is rapidly becoming a significant topic of present interest all over the world, and environmental modelling has a very high priority in various scientific fields, respectively. Different optimizations of the Latin Hypercube Sampling algorithm have been used in our sensitivity studies of the model output results for some air pollutants with respect to the emission levels and some chemical reactions rates.

3

In vessel corium propagation sensitivity study of reactor pressure vessel rupture time with PROCOR platform

Skrzypek E., Skrzypek M., Saas L., Letellier R.

Journal of Power Technologies

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2017

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Vol. 97, nr 2

110--116

EN

The problem of corium propagation for PWRs in the Reactor Pressure Vessel (RPV) and the timing of RPV failure is one of the main issues of study in the area of severe accidents. The PROCOR numerical platform created by the CEA severe accident laboratory is modelling corium propagation for LWRs, its relocation to the Lower Plenum and RPV failure. The idea behind the platform was to provide a tool that is fast enough to be able to perform numerous calculations within a reasonable time frame in order to deliver a statistical study. Work on the development of models that describe in-vessel issues is being pursued through simplified phenomena modelling, their verification and sensitivity studies. Recent activities related to PROCOR development involved cooperation between French CEA experts and Polish PhD students, who were engaged in the topics of core support plate modelling and analysis of the phenomena occurring in a thin metallic layer on top of the corium pool. Those issues were identified as strongly influencing the course of severe accidents and the timing of RPV failure. In some sensitivity studies performed on a given generic high power Light Water Reactor with heavy reflector, two groups of RPV ruptures were distinguished related to the two issues, which provided motivation for further work on these topics. The paper will present a sensitivity study of corium propagation in order to identify the relevance of those two issues for the timing of RPV rupture.

4

Sensitivity Study of Low-Power Turboshaft Engine Based on Analysis of Thermodynamic Cycle

Jaeschke A., Karczewski M.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2015

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nr 148

77--89

EN

Turboshaft engines are extensively used in the industry and the aviation. Especially in this latter application their optimization with respect to a fuel consumption, mass reduction and performance is of utmost importance. In this paper the algorithm for analysis of different configurations of turboshaft engines from the point of view of thermodynamic cycle is presented. The algorithm is validated by comparison with an available software considered as “the industry standard”. The code was used to perform extensive sensitivity study of parameters of a prepared turboshaft engine model.

PL

Silniki turbospalinowe są szeroko stosowane w przemyśle i lotnictwie. Szczególnie w przypadku zastosowań lotniczych ich optymalizacja pod względem zmniejszenia zużycia paliwa i masy własnej jest zagadnieniem szczególnie ważnym. W artykule przedstawiono program do analizy różnych konfiguracji silników turbospalinowych z punktu widzenia obiegu termodynamicznego. Program ten został sprawdzony poprzez porównanie otrzymanych wyników z innym dostępnym programem, będącym szeroko używanym w zastosowaniach przemysłowych. Opracowany program został następnie wykorzystany do przeprowadzenia obszernej analizy wrażliwości parametrów modelu silnika turbospalinowego.

5

On practical problems with verification and validation of computational models

Kwaśniewski L.

Archives of Civil Engineering

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2009

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Vol. 55, nr 3

323-346

EN

This paper discusses the concepts of verification and validation (V&V) in computational mechanics by referring to recently published papers and guides on V&V that define some best practices and show directions for future development. The perspective of an analyst, who develops computational models, makes runs, and analyzes numerical results mostly using software based on the finite element method, is presented. The considerations emphasize practical problems encountered in the V&V process, potential sources of errors and uncertainties, the importance of sensitivity study, new ideas regarding the relationship between validation and verification, differences between calibration and validation, new aspects of the validation metrics and validation hierarchy, and guides for designing validation experiments. The discussion is illustrated by computational problem examples. This paper presents some skepticism toward the formally probabilistic approach described in many publications. The examples presented in this paper show that for the non-linear problems there are unavoidable errors that are an inherent part of the solution procedures. For the wide range of conditions found in practice, it is impossible to define general requirements guaranteeing satisfying accuracy, and unexpected large errors can be encountered. To identify such discrepancies, called here the errors of discretization, verification through the testing of different solution options is necessary. Moreover, separation of all sources of errors is today impossible for many complex systems.

PL

Przedstawiono dyskusję na temat weryfikacji i walidacji (V&V) w mechanice komputerowej, w odniesieniu do opublikowanych w ostatnim czasie artykułów naukowych i wytycznych dotyczących tej tematyki. W pracy przedstawiono punkt widzenia użytkownika programów numerycznych opartych na metodzie elementów skończonych, który zajmuje się opracowywaniem modeli numerycznych, przeprowadza obliczenia i analizuje otrzymane wyniki. Prezentowana dyskusja jest skoncentrowana na praktycznych problemach związanych z przeprowadzaniem sformalizowanych procedur weryfikacji i walidacji. Rozważania dotyczą: identyfikacji potencjalnych źródet błędów obliczeń, nieokreśloności obliczeń, przydatności studiów parametrycznych, nowych idei dotyczących zależności pomiędzy weryfikacją i walidacją, różnic pomiędzy kalibracją modelu numerycznego a jego walidacją, nowych aspektów miar stosowanych w procesie walidacji i walidacji hierarchicznej, wskazówek dla projektowania eksperymentów walidacyjnych. Przedstawiona dyskusja jest zilustrowana wybranymi przykładami obliczeniowymi. W pracy przedstawiono trudności związane z praktycznym zastosowaniem sformalizowanego podejścia probabilistycznego, prezentowanego w wielu współczesnych publikacjach. Przykłady przedstawione w artykule wskazują, że w wielu zagadnieniach silnie nieliniowych, rozwiązywanych przy pomocy metod numerycznych, mogą pojawić się nieusuwalne błędy obliczeń. Dla wielu zagadnień, występujących w praktyce inżynierskiej, nie jest możliwym sformułowanie uniwersalnych wymagań, których zastosowanie gwarantowałoby odpowiedni poziom dokładności obliczeń, a w wielu przypadkach mogą pojawić się niespodziewanie duże błędy. W celu identyfikacji tego typu błędów, związanych z szeroko pojętym procesem dyskretyzacji modelu numerycznego, niezbędna jest weryfikacja różnorodnych opcji numerycznych. Dodatkowo, rozdzielenie wszystkich źródeł błędów obliczeń wydaje się niemożliwe dla wielu złożonych systemów.

6

Large-eddy simulation of katabatic winds. Part 2: Sensitivity study and comparison

Axelsen S.L., van Dop H.

Acta Geophysica

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2009

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Vol. 57, no. 4

837-856

EN

The effects of the slope angle, surface buoyancy flux, and background stratification on steady-state katabatic winds are studied using large-eddy simulation (LES). The numerical code was described and validated in a companion paper (Part 1). Our numerical results are interpreted in the light of analytical Prandtl model, and we find that our vertical profiles of the downslope velocity, buoyancy, and the momentum and buoyancy fluxes exhibit many of the features from the analytical solution. On the other hand, there are also differences between the analytical and numerical results due to the assumptions in the analytical model. One of the assumptions is that the Prandtl number is constant throughout the boundary layer. However, the simulations show that this number varies with height, and also that the Prandtl number increases with increasing gradient Richardson number. The immediate benefit of LES over analytical models is its capability of resolving turbulent motions. In our study of the turbulence kinetic energy budgets, we find that the wind shear is the largest production term, and that it is mainly balanced by turbulence dissipation. Near the wind maximum, where the shear vanishes, the turbulence transport is the only production term.