environmental models
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2022 ◽  
pp. 307-327
Author(s):  
Christina Skonberg ◽  
Mariko Thorbecke

2021 ◽  
Vol 19 (11) ◽  
pp. 84-94
Author(s):  
Aymen Abdul Rasool Jawad ◽  
Dr. Nagham Mahmood Aljamali

The last decades of this century witnessed a wide interest in three heterogeneous compounds, especially nitrogen atoms, which were represented by triazole rings and their derivatives, whose effects were studied in the widest medical and pharmaceutical journals and as anti-cancer agents and other groups that are characterized by the presence of electronic pairs, which have given greater importance for this reason. In order to increase the effectiveness of any compound, it must include in its composition active groups, donor groups, or electron pairs, and this has been proven by researchers in biochemistry, coordination research, reagent chemistry, reagents, analytical chemistry, estimation of elements and ions in river water and environmental models. Extensive studies have been conducted for the reagents under study to determine their chemical structures through microscopic technical examinations, spectroscopic techniques (Uv-Vis, FT.IR, H.NMR, Mass)–spectra, also Analytical studies like: {Thermal study, TLC–Technique, Scanning Electron Microscopy (FESEM)} and other physico-chemical measurements.


Author(s):  
Zahari Zlatev ◽  
Ivan Dimov ◽  
István Faragó ◽  
Krassimir Georgiev ◽  
Ágnes Havasi

AbstractThe numerical treatment of an atmospheric chemical scheme, which contains 56 species, is discussed in this paper. This scheme is often used in studies of air pollution levels in different domains, as, for example, in Europe, by large-scale environmental models containing additionally two other important physical processes—transport of pollutants in the atmosphere (advection) and diffusion phenomena. We shall concentrate our attention on the efficient numerical treatment of the chemical scheme by using Implicit Runge–Kutta Methods combined with accurate and efficient advanced versions of the Richardson Extrapolation. A Variable Stepsize Variable Formula Method is developed in order to achieve high accuracy of the calculated results within a reasonable computational time. Reliable estimations of the computational errors when the proposed numerical methods are used in the treatment of the chemical scheme will be demonstrated by presenting results from several representative runs and comparing these results with “exact” concentrations obtained by applying a very small stepsize during the computations. Results related to the diurnal variations of some of the chemical species will also be presented. The approach used in this paper does not depend on the particular chemical scheme and can easily be applied when other atmospheric chemical schemes are selected.


2021 ◽  
Vol 13 (22) ◽  
pp. 4635
Author(s):  
Rakesh Chandra Joshi ◽  
Dongryeol Ryu ◽  
Gary J. Sheridan ◽  
Patrick N. J. Lane

The conventional Land Surface Temperature (LST)–Normalized Difference Vegetation Index (NDVI) trapezoid model has been widely used to retrieve vegetation water stress. However, it has two inherent limitations: (1) its complex and computationally intensive parameterization for multi-temporal observations and (2) deficiency in canopy water content information. We tested the hypothesis that an improved water stress index could be constructed by the representation of canopy water content information to the LST–NDVI trapezoid model. Therefore, this study proposes a new index that combines three indicators associated with vegetation water stress: canopy temperature through LST, canopy water content through Surface Water Content Index (SWCI), and canopy fractional cover through NDVI in one temporally transferrable index. Firstly, a new optical space of SWCI–NDVI was conceptualized based on the linear physical relationship between shortwave infrared (SWIR) and soil moisture. Secondly, the SWCI–NDVI feature space was parameterized, and an index d(SWCI, NDVI) was computed based on the distribution of the observations in the SWCI–NDVI spectral space. Finally, standardized LST (LST/long term mean of LST) was combined to d(SWCI, NDVI) to give a new water stress index, Temperature Vegetation Water Stress Index (TVWSI). The modeled soil moisture from the Australian Water Resource Assessment—Landscape (AWRA-L) and Soil Water Fraction (SWF) from four FLUXNET sites across Victoria and New South Wales were used to evaluate TVWSI. The index TVWSI exhibited a high correlation with AWRA-L soil moisture (R2 of 0.71 with p < 0.001) and the ground-based SWF (R2 of 0.25–0.51 with p < 0.001). TVWSI predicted soil moisture more accurately with RMSE of 21.82 mm (AWRA-L) and 0.02–0.04 (SWF) compared to the RMSE ranging 28.98–36.68 mm (AWRA-L) and 0.03–0.05 (SWF) were obtained for some widely used water stress indices. The TVWSI could also be a useful input parameter for other environmental models.


2021 ◽  
Author(s):  
Dmytro Perepolkin

The present literature review aims to perform a survey of the decision support models used in waterfowl management. Special attention is dedicated to the origins and practice of adaptive management and modern applications of agent-based models focusing on explicit acknowledgment and treatment of uncertainty in these models.


2021 ◽  
Vol 2 ◽  
Author(s):  
Rachel Gjelsvik Tiller ◽  
Georgia Destouni ◽  
Mariana Golumbeanu ◽  
Zahra Kalantari ◽  
Erasmia Kastanidi ◽  
...  

To reach the global aspiration of 17 ambitious SDGs, local realities must be integrated. Often, models are developed based on quantitative statistical data sources from databases on environmental indicators or economics to assess how a given SDG can be achieved. This process however removes the local realities from the equation. How can you best include stakeholders in this mathematical modelling processes distanced from their local realities, though, and ensure higher probability of future compliance with top-down global decisions that may have local consequences once implemented? When researching stakeholder involvement and their ability to form public policy, their opinions often get reported as a single assessment, like counting the fish in the ocean once and stating that as a permanent result. Too seldom do stakeholders get invited back and given the opportunity to validate results and allow researchers to adjust their models based on on-the-ground validation or change requests. We tested the full integration of stakeholders in the modelling process of environmental topics in six different case areas across Europe, with each area holding six sectoral and one inter-sectoral workshops. In these workshops, the scope of the issues relevant to the stakeholders was driven by first the sectoral priorities of the given sector, followed by a merging of issues. In this process, we were able to identify what the commonalities between different sectors were and where synergies lay in terms of governance paths. These results were then returned to the stakeholders in a mixed session where they were able to come with feedback and advice on the results researchers presented, so that the models reflected more closely the perceptions of the regional actors. We present these methods and reflect on the challenges and opportunities of using this deep-integration method to integrate qualitative data from stakeholder inclusion in a quantitative model.


2021 ◽  
Author(s):  
Marina R. L. Mautner ◽  
Laura Foglia ◽  
Jonathan D. Herman

Abstract. Urban groundwater management requires complex environmental models to represent interactions between hydrogeological processes and infrastructure systems. While the impacts of external uncertainties have been widely studied, there is limited understanding of how decision support is altered by endogenous uncertainties arising from model parameters and observations used for calibration. This study investigates (1) the importance of observation choice and parameter values on aquifer management objectives when controlling for model error, and (2) how the relative performance of management alternatives varies when exposed to endogenous uncertainties, individually and in combination. We use a spatially distributed groundwater model of the Valley of Mexico, where aquifer management alternatives include demand management, targeted infiltration, and wastewater reuse. The effects of uncertainty are evaluated using global sensitivity analysis, performance ranking of alternatives under a range of human-natural parameters, and identification of behavioral parameter sets filtered with an error metric calculated from varying subsets of observations. Results show that the parameters governing hydraulic conductivity and total water use in the basin have the greatest effect on management objectives. Model errors are not necessarily controlled by the same parameters as the objectives needed for decision-making. Additionally, observational and parameter uncertainty each play a larger role in objective variation than the management alternatives themselves. Finally, coupled endogenous uncertainties have amplifying effects on decision-making, leading to larger variations in the ranking of management alternatives than each on their own. This study highlights how the uncertain parameters of a physically-based model and their interactions with uncertain observations can affect water supply planning decisions in densely populated urban areas.


2021 ◽  
Vol 2090 (1) ◽  
pp. 012116
Author(s):  
Angel Porras-Hermoso ◽  
Javier Cubas ◽  
Santiago Pindado

Abstract Attitude determination represents a fundamental task for most of the spacecrafts. It relies on three basic aspects: 1) sensors selection, 2) relevant environmental conditions estimation, and 3) algorithms that relate the sensor measurements to the expected conditions in the reference frame. Each one has its own impact on the accuracy that the system can achieve. Besides, two factors stand out above the others in terms of accuracy: 1) sensor quality (calibration, range, etc), and 2) precision of the environmental models. The computation of the satellite attitude needs at least two independent measurements (magnetometers, solar sensors...), whit their corresponding simulated measurements in the reference frame. Nevertheless, the number of measurements can be reduced to one if the satellite attitude is constrained. This paper describes a procedure to calculate satellites’ attitude and the main environmental models used (Earth magnetic model, Sun position model, Albedo model), including orbit propagation. This methodology can be extended to measure the performance of a sensor if the satellite attitude can be derived from other measurements and satellite constrains. The methodology is checked with data from the UPMSat-2 mission (launched in September 2020 within the VEGA VV16 mission). This is a 50-kg satellite designed and developed at the Universidad Politécnica de Madrid (UPM).


Author(s):  
Heather M. Cowardin ◽  
John M. Hostetler ◽  
James I. Murray ◽  
Jacqueline A. Reyes ◽  
Corbin L. Cruz

AbstractThe NASA Orbital Debris Program Office (ODPO) develops, maintains, and updates orbital debris environmental models, such as the NASA Orbital Debris Engineering Model (ORDEM), to support satellite designers and operators by estimating the risk from orbital debris impacts on their vehicles in orbit. Updates to ORDEM utilize the most recent validated datasets from radar, optical, and in situ sources to provide estimates of the debris flux as a function of size, material density, impact speed, and direction along a mission orbit. On-going efforts within the NASA ODPO to update the next version of ORDEM include a new parameter that highly affects the damage risk – shape. Shape can be binned by material density and size to better understand the damage assessments on spacecraft. The in situ and laboratory research activities at the NASA ODPO are focused on cataloging and characterizing fragments from a laboratory hypervelocity-impact test using a high-fidelity, mock-up satellite, DebriSat, in controlled and instrumented laboratory conditions. DebriSat is representative of present-day, low Earth orbit satellites, having been constructed with modern spacecraft materials and techniques. The DebriSat fragment ensemble provides a variety of shapes, bulk densities, and dimensions. Fragments down to 2 mm in size are being characterized by their physical and derived properties. A subset of fragments is being analyzed further in NASA’s Optical Measurement Center (OMC) using broadband, bidirectional reflectance measurements to provide insight into the optical-based NASA Size Estimation Model. Additionally, pre-impact spectral measurements on a subset of DebriSat materials were acquired for baseline material characterization. This paper provides an overview of DebriSat, the status of the project, and ongoing fragment characterization efforts within the OMC.


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