scholarly journals A comparative study in aquifer parameter estimation using MFree point collocation method with evolutionary algorithms

2019 ◽  
Vol 21 (3) ◽  
pp. 455-473 ◽  
Author(s):  
Alice Thomas ◽  
T. I. Eldho ◽  
A. K. Rastogi ◽  
Partha Majumder
Keyword(s):  
Comparative Study ◽  
Collocation Method ◽  
Transport Processes ◽  
State Variables ◽  
Data Set ◽  
Swarm Optimization ◽  
Aquifer Parameters ◽  
Point Collocation ◽  
Longitudinal Dispersivity ◽  
Transverse Dispersivity

Abstract In this study, we present a comparative assessment of simulation-optimization (S-O) models to estimate aquifer parameters such as transmissivity, longitudinal dispersivity, and transverse dispersivity. The groundwater flow and contaminant transport processes are simulated using the mesh-free radial basis point collocation method (RPCM). Four different S-O models are developed by combining the RPCM model separately with genetic algorithm (GA), differential evolution (DE), cat swarm optimization (CSO), and particle swarm optimization (PSO). The objective of the S-O model is to minimize a composite objective function with transmissivity, longitudinal dispersivity, and transverse dispersivity as decision variables. Hydraulic head and contaminant concentration at observation points are the state variables. The S-O models are used to estimate aquifer parameters of a confined aquifer with nine zones. It is found that RPCM-based DE, CSO, and PSO models are more accurate in estimating aquifer parameters than RPCM-GA. However, for noisy observed data, the RPCM-CSO model outperforms other models. The efficiency of the RPCM-CSO model over other models is further established by performing reliability analysis to the noisy observed data set. The comparative study reflects the efficacy of CSO over GA, DE, and PSO.

scholarly journals Effects of polar stratospheric clouds in the Nimbus 7 LIMS Version 6 data set

2016 ◽  
Vol 9 (7) ◽  
pp. 2927-2946 ◽  
Author(s):  
Ellis Remsberg ◽  
V. Lynn Harvey
Keyword(s):  
Stratospheric Aerosol ◽  
Transport Processes ◽  
The Arctic ◽  
Additional Parameter ◽  
Polar Stratospheric Clouds ◽  
Data Set ◽  
Screening Criteria ◽  
Temperature Thresholds ◽  
Level 3 ◽  
Stratospheric Clouds

Abstract. The historic Limb Infrared Monitor of the Stratosphere (LIMS) measurements of 1978–1979 from the Nimbus 7 satellite were re-processed with Version 6 (V6) algorithms and archived in 2002. The V6 data set employs updated radiance registration methods, improved spectroscopic line parameters, and a common vertical resolution for all retrieved parameters. Retrieved profiles are spaced about every 1.6° of latitude along orbits and include the additional parameter of geopotential height. Profiles of O3 are sensitive to perturbations from emissions of polar stratospheric clouds (PSCs). This work presents results of implementing a first-order screening for effects of PSCs using simple algorithms based on vertical gradients of the O3 mixing ratio. Their occurrences are compared with the co-located, retrieved temperatures and related to the temperature thresholds needed for saturation of H2O and/or HNO3 vapor onto PSC particles. Observed daily locations where the major PSC screening criteria are satisfied are validated against PSCs observed with the Stratospheric Aerosol Monitor (SAM) II experiment also on Nimbus 7. Remnants of emissions from PSCs are characterized for O3 and HNO3 following the screening. PSCs may also impart a warm bias in the co-located LIMS temperatures, but by no more than 1–2 K at the altitudes of where effects of PSCs are a maximum in the ozone; thus, no PSC screening was applied to the V6 temperatures. Minimum temperatures vary between 187 and 194 K and often occur 1 to 2 km above where PSC effects are first identified in the ozone (most often between about 21 and 28 hPa). Those temperature–pressure values are consistent with conditions for the existence of nitric acid trihydrate (NAT) mixtures and to a lesser extent of super-cooled ternary solution (STS) droplets. A local, temporary uptake of HNO3 vapor of order 1–3 ppbv is indicated during mid-January for the 550 K surface. Seven-month time series of the distributions of LIMS O3 and HNO3 are shown based on their gridded Level 3 data following the PSC screening. Zonal coefficients of both species are essentially free of effects from PSCs on the 550 K surface, based on their average values along PV contours and in terms of equivalent latitude. Remnants of PSCs are still present in O3 on the 450 K surface during mid-January. It is judged that the LIMS Level 3 data are of good quality for analyzing the larger-scale, stratospheric chemistry and transport processes during the Arctic winter of 1978–1979.

scholarly journals A Comparative Study of Students' Perceptions about Career Options in Art & Design

2021 ◽  
Vol VI (II) ◽  
pp. 88-96
Author(s):  
Gouhar Pirzada ◽  
Fariha Gul ◽  
Muhammad Abdullah Mahmood
Keyword(s):  
Comparative Study ◽  
Secondary Students ◽  
Quantitative Research ◽  
Educational Programs ◽  
Prospective Students ◽  
Data Set ◽  
Design Studies ◽  
Study Approach ◽  
Career Options ◽  
Professional Degrees

This research aims to examine secondary and higher secondary students' perceptions about career options related to Art & Design studies. A comparative study approach is conducted between the secondary and higher secondary students who opted for Art & Design and the prospective students of Art & Design. Each data set includes 200 respondents from both types of students, making a data set of 400 respondents. Based on constructionism and symbolic, philosophical assumptions, quantitative research methodology has been induced to complete this research. The data is gathered through structured telephonic interviews to analyze the responses. For this research, a checklist was designed that included the same type of questions from both types of students. The results show that the students, specifically in the context of Pakistan, look forward to being employed in a lavish environment through seeking professional degrees apart from whether the field they are choosing would win their interest. This study recommends researching the institutes where Art & design is not a part of the educational programs to transmit the attention of authorities towards it.

scholarly journals The Atmospheric Carbon and Transport (ACT) – America Mission

2021 ◽  
pp. 1-54
Author(s):  
Kenneth J. Davis ◽  
Edward V. Browell ◽  
Sha Feng ◽  
Thomas Lauvaux ◽  
Michael D. Obland ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Eastern United States ◽  
State Variables ◽  
Data Set ◽  
Spatial Gradients ◽  
Research Aircraft ◽  
In Situ Sensors ◽  
Atmospheric Carbon ◽  
Model Ensembles

AbstractThe Atmospheric Carbon and Transport (ACT) – America NASA Earth Venture Suborbital Mission set out to improve regional atmospheric greenhouse gas (GHG) inversions by exploring the intersection of the strong GHG fluxes and vigorous atmospheric transport that occurs within the midlatitudes. Two research aircraft instrumented with remote and in situ sensors to measure GHG mole fractions, associated trace gases, and atmospheric state variables collected 1140.7 flight hours of research data, distributed across 305 individual aircraft sorties, coordinated within 121 research flight days, and spanning five, six-week seasonal flight campaigns in the central and eastern United States. Flights sampled 31 synoptic sequences, including fair weather and frontal conditions, at altitudes ranging from the atmospheric boundary layer to the upper free troposphere. The observations were complemented with global and regional GHG flux and transport model ensembles. We found that midlatitude weather systems contain large spatial gradients in GHG mole fractions, in patterns that were consistent as a function of season and altitude. We attribute these patterns to a combination of regional terrestrial fluxes and inflow from the continental boundaries. These observations, when segregated according to altitude and air mass, provide a variety of quantitative insights into the realism of regional CO2 and CH4 fluxes and atmospheric GHG transport realizations. The ACT-America data set and ensemble modeling methods provide benchmarks for the development of atmospheric inversion systems. As global and regional atmospheric inversions incorporate ACT-America’s findings and methods, we anticipate these systems will produce increasingly accurate and precise sub-continental GHG flux estimates.

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