Dan Van Peursem - Academia.edu (original) (raw)
Papers by Dan Van Peursem
ABSTRACT Thesis (Ph. D.)--University of Nebraska--Lincoln, 1997. Includes bibliographical referen... more ABSTRACT Thesis (Ph. D.)--University of Nebraska--Lincoln, 1997. Includes bibliographical references.
Wear, Apr 1, 2018
Erosion in slurry pipeline systems has received a lot of attention due to the economic impact in ... more Erosion in slurry pipeline systems has received a lot of attention due to the economic impact in the cost of replacing portions of the pipelines. Most attention has been merited from the oil and gas industry. However, remediation of reservoirs behind dams built along major river systems is also a major reason this investigation is so important and provides the background for some of the parameters of this paper. Given that straight pipes are the predominant part of most systems, our attention is restricted to long straight pipes that are far enough away from elbows, welds, and tee fittings that would alter the flow. A model predicting pipeline erosion from smooth river sands suspended in aqueous slurries due to inter-particle collisions which go on to impact the wall of the pipe on straight pipelines is presented. The model is based on physical laws governing the flow of the slurry, how these velocity gradients affect the number of particles impacting the pipe wall, and the amount of wall particle removed from such impacts based on their kinetic energy. The model considers particles with diameters ranging from 50 to 350 µm, velocities of 3.5-6 m/s, and sand slurry concentrations of 10-40% by volume.
Journal of Hydrology, Jun 1, 2007
The dipole flow test (DFT) was applied to investigate the effects of entrapped air on quasi-satur... more The dipole flow test (DFT) was applied to investigate the effects of entrapped air on quasi-saturated hydraulic conductivity (K) in a cylindrical aquifer model (sand tank). The sand tank was equipped with 58 spatially distributed piezometers and screened well to accommodate the dipole probe (DP). The experiments included tests with and without pre-saturation of the sand medium with CO2, a
Journal of Hydrology, Sep 1, 1999
Flow structure around a recirculation well in a uniform anisotropic aquifer is investigated using... more Flow structure around a recirculation well in a uniform anisotropic aquifer is investigated using potential theory and Stokes' stream function techniques. A vertical recirculation well consists of two screened sections (chambers) separated by an impermeable casing: one section extracts water from the aquifer and the other section injects the water back into the aquifer. Analytical formulae are derived for the drawdown and the stream function for a model in which the extraction and injection chambers of the well are modeled as uniformly distributed cylindrical sinks and sources, respectively. Travel times are analyzed for water particles traveling from the injection chamber to the extraction chamber along streamlines containing various percentages of the flow. We consider a disturbed zone (skin) having properties which are different from those in the uniform anisotropic aquifer owing to disturbance of the area near the well during installation. The effects of this skin on the streamlines and travel times are analyzed for various lengths separating the chambers and for various skin conductivities. The method completely eliminates the use of numerical finite-difference or finite-element methods and can be used for optimization of technological parameters in a remediation system.
Journal of healthcare informatics research, May 1, 2021
Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. E... more Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. Early efforts to predict hospital bed needs focused on deriving predictions from SIR models, largely at the level of countries, provinces, or states. In the USA, these models rely on data reported by state health agencies. However, predicting disease and hospitalization dynamics at the state level is complicated by geographic variation in disease parameters. In addition, it is difficult to make forecasts early in a pandemic due to minimal data. Bayesian approaches that allow models to be specified with informed prior information from areas that have already completed a disease curve can serve as prior estimates for areas that are beginning their curve. Here, a Bayesian non-linear regression (Weibull function) was used to forecast cumulative and active COVID-19 hospitalizations for SD, USA, based on data available up to 2020-07-22. As expected, early forecasts were dominated by prior information, which was derived from New York City. Importantly, hospitalization trends differed within South Dakota due to early peaks in an urban area, followed by later peaks in rural areas of the state. Combining these trends led to altered forecasts with relevant policy implications.
The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the o... more The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the object of investigation of numerous biologists due to the potentially high risk of contamination of the human population. In the present paper we construct and analyze a model describing the interaction between the prairie dog population (as the host population) and the flea population (as the vector population) and derive the existence (under certain conditions impose to the main parameter) of an equilibrium that plays the role of a global attractor.
This paper presents analytical models of several different groundwater flow problems having vario... more This paper presents analytical models of several different groundwater flow problems having various flow geometries. One model considers a vertical circulation flow in an infinite domain with a skin layer around the extraction well. The second model considers a vertical circulation flow in a cylindrical tank without the skin layer. The third model considers an extraction well with a ring source. Analytical formulas for the drawdown and stream functions are derived for all three of these models. The last model is a contaminant concentration model with a uniform initial contaminant concentration inside a cylinder about the pumping well and no contaminant outside this cylinder. Analytical formulas for the concentration are derived for general adsorption isotherms in this model.
Mathematics and Computer Education, 2012
INTRODUCTION In the 2006-2007 academic year, the University of South Dakota formed a mathematics ... more INTRODUCTION In the 2006-2007 academic year, the University of South Dakota formed a mathematics task force to evaluate student success in introductory mathematics courses and to investigate the question of quantitative literacy and its meaning for graduates of a liberal arts institution. Questions about this paper or study may be directed to Dan Van Peursem at dpuersem@usd.edu. The need for Quantitative Literacy courses was established in reports from the Mathematical Association of America (MAA) [21], American Mathematical Association of Two- Year Colleges (AMATYC) [2, 4], and the College Board [25]. National focus groups have been formed around this topic including the Special Interest Group of the MAA on Quantitative Literacy (SIGMAA-QL) and the National Numeracy Network (NNN), both formed in 2004. In the ensuing years, numerous reports and courses have been developed centering on the topic of Quantitative Literacy [8, 14, 15, 16, 17, 22, 23, 24, 25, 26, 27]. As recently as 2010...
The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the o... more The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the object of investigation of numerous biologists due to the potentially high risk of contamination of the human population. In the present paper we construct and analyze a model describing the interaction between the prairie dog population (as the host population) and the flea population (as the vector population) and derive the existence (under certain conditions impose to the main parameter) of an equilibrium that plays the role of a global attractor. Key–Words: Stability of Equilibria, Global attractor, Bifurcation.
Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. E... more Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. Early efforts to predict hospital bed needs focused on deriving predictions from SIR models, largely at the level of countries, provinces, or states. In the United States, these models rely on data reported by state health agencies. However, predictive disease and hospitalization dynamics at the state level are complicated by geographic variation in disease parameters. In addition it is difficult to make forecasts early in a pandemic due to minimal data. However, Bayesian approaches that allow models to be specified with informed prior information from areas that have already completed a disease curve can serve as prior estimates for areas that are beginning their curve. Here, a Bayesian non-linear regression (Weibull function) was used to forecast cumulative and active COVID-19 hospitalizations for South Dakota, USA. As expected, early forecasts were dominated by prior information, which...
Wseas Transactions on Biology and Biomedicine, 2013
Thesis (Ph. D.)--University of Nebraska--Lincoln, 1997. Includes bibliographical references.
Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling w... more Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling will be presented. The first problem involves understanding the notion oscillation for Bezier surfaces, the freeform polynomial surfaces most common in Computer ...
Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling w... more Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling will be presented. The first problem involves understanding the notion oscillation for Bezier surfaces, the freeform polynomial surfaces most common in Computer ...
The article explores the efficacy of a Quantitative Literacy course in preparing students for pot... more The article explores the efficacy of a Quantitative Literacy course in preparing students for potential outcomes in traditional College Algebra course. It notes that the establishment of the course is aimed at providing students with alternative to college algebra, and facilitating their understanding on mathematics that they encounter in daily situations. Moreover, it indicates the significance of Quantitative Literacy course in elevating students' perceptions on the usefulness of mathematics.
WSEAS Transactions on Biology and Biomedicine
In this work we model the spread of sylvatic plague between two prairie dog colonies. The mathema... more In this work we model the spread of sylvatic plague between two prairie dog colonies. The mathematical model is one where a population of fleas transmits the plague to the host population of prairie dogs. Distance between the two colonies is examined as well as using insecticide to increase the death rates on the fleas that spread the disease between prairie dogs. Semi-analytical solutions for equilibria are derived using a perturbation series approach.
WSEAS Transactions on Biology and Biomedicine
In this work we model a pandemic where individuals are first infected with the influenza virus an... more In this work we model a pandemic where individuals are first infected with the influenza virus and later contract a secondary bacterial infection. The model uses a modified SIR approach with standard analytical and qualitative analysis. Theoretical questions are investigated concerning the proportion of the population to initially vaccinate for influenza, the proportion of the population to quarantine after being infected with influenza, and how improved treatments of bacterial infections all would play into reducing the net number of deaths.
Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling w... more Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling will be presented. The first problem involves understanding the notion oscillation for Bezier surfaces, the freeform polynomial surfaces most common in Computer ...
Transport in porous media, 1998
Potential theory and Stokes' stream function techniques are used to investigate the flow str... more Potential theory and Stokes' stream function techniques are used to investigate the flow structure around the recirculation system developed by Gvirtzman and Gorelick (1992, 1993), which consists of an extraction well and a gallery (trench) for the recharge of ...
ABSTRACT Thesis (Ph. D.)--University of Nebraska--Lincoln, 1997. Includes bibliographical referen... more ABSTRACT Thesis (Ph. D.)--University of Nebraska--Lincoln, 1997. Includes bibliographical references.
Wear, Apr 1, 2018
Erosion in slurry pipeline systems has received a lot of attention due to the economic impact in ... more Erosion in slurry pipeline systems has received a lot of attention due to the economic impact in the cost of replacing portions of the pipelines. Most attention has been merited from the oil and gas industry. However, remediation of reservoirs behind dams built along major river systems is also a major reason this investigation is so important and provides the background for some of the parameters of this paper. Given that straight pipes are the predominant part of most systems, our attention is restricted to long straight pipes that are far enough away from elbows, welds, and tee fittings that would alter the flow. A model predicting pipeline erosion from smooth river sands suspended in aqueous slurries due to inter-particle collisions which go on to impact the wall of the pipe on straight pipelines is presented. The model is based on physical laws governing the flow of the slurry, how these velocity gradients affect the number of particles impacting the pipe wall, and the amount of wall particle removed from such impacts based on their kinetic energy. The model considers particles with diameters ranging from 50 to 350 µm, velocities of 3.5-6 m/s, and sand slurry concentrations of 10-40% by volume.
Journal of Hydrology, Jun 1, 2007
The dipole flow test (DFT) was applied to investigate the effects of entrapped air on quasi-satur... more The dipole flow test (DFT) was applied to investigate the effects of entrapped air on quasi-saturated hydraulic conductivity (K) in a cylindrical aquifer model (sand tank). The sand tank was equipped with 58 spatially distributed piezometers and screened well to accommodate the dipole probe (DP). The experiments included tests with and without pre-saturation of the sand medium with CO2, a
Journal of Hydrology, Sep 1, 1999
Flow structure around a recirculation well in a uniform anisotropic aquifer is investigated using... more Flow structure around a recirculation well in a uniform anisotropic aquifer is investigated using potential theory and Stokes' stream function techniques. A vertical recirculation well consists of two screened sections (chambers) separated by an impermeable casing: one section extracts water from the aquifer and the other section injects the water back into the aquifer. Analytical formulae are derived for the drawdown and the stream function for a model in which the extraction and injection chambers of the well are modeled as uniformly distributed cylindrical sinks and sources, respectively. Travel times are analyzed for water particles traveling from the injection chamber to the extraction chamber along streamlines containing various percentages of the flow. We consider a disturbed zone (skin) having properties which are different from those in the uniform anisotropic aquifer owing to disturbance of the area near the well during installation. The effects of this skin on the streamlines and travel times are analyzed for various lengths separating the chambers and for various skin conductivities. The method completely eliminates the use of numerical finite-difference or finite-element methods and can be used for optimization of technological parameters in a remediation system.
Journal of healthcare informatics research, May 1, 2021
Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. E... more Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. Early efforts to predict hospital bed needs focused on deriving predictions from SIR models, largely at the level of countries, provinces, or states. In the USA, these models rely on data reported by state health agencies. However, predicting disease and hospitalization dynamics at the state level is complicated by geographic variation in disease parameters. In addition, it is difficult to make forecasts early in a pandemic due to minimal data. Bayesian approaches that allow models to be specified with informed prior information from areas that have already completed a disease curve can serve as prior estimates for areas that are beginning their curve. Here, a Bayesian non-linear regression (Weibull function) was used to forecast cumulative and active COVID-19 hospitalizations for SD, USA, based on data available up to 2020-07-22. As expected, early forecasts were dominated by prior information, which was derived from New York City. Importantly, hospitalization trends differed within South Dakota due to early peaks in an urban area, followed by later peaks in rural areas of the state. Combining these trends led to altered forecasts with relevant policy implications.
The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the o... more The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the object of investigation of numerous biologists due to the potentially high risk of contamination of the human population. In the present paper we construct and analyze a model describing the interaction between the prairie dog population (as the host population) and the flea population (as the vector population) and derive the existence (under certain conditions impose to the main parameter) of an equilibrium that plays the role of a global attractor.
This paper presents analytical models of several different groundwater flow problems having vario... more This paper presents analytical models of several different groundwater flow problems having various flow geometries. One model considers a vertical circulation flow in an infinite domain with a skin layer around the extraction well. The second model considers a vertical circulation flow in a cylindrical tank without the skin layer. The third model considers an extraction well with a ring source. Analytical formulas for the drawdown and stream functions are derived for all three of these models. The last model is a contaminant concentration model with a uniform initial contaminant concentration inside a cylinder about the pumping well and no contaminant outside this cylinder. Analytical formulas for the concentration are derived for general adsorption isotherms in this model.
Mathematics and Computer Education, 2012
INTRODUCTION In the 2006-2007 academic year, the University of South Dakota formed a mathematics ... more INTRODUCTION In the 2006-2007 academic year, the University of South Dakota formed a mathematics task force to evaluate student success in introductory mathematics courses and to investigate the question of quantitative literacy and its meaning for graduates of a liberal arts institution. Questions about this paper or study may be directed to Dan Van Peursem at dpuersem@usd.edu. The need for Quantitative Literacy courses was established in reports from the Mathematical Association of America (MAA) [21], American Mathematical Association of Two- Year Colleges (AMATYC) [2, 4], and the College Board [25]. National focus groups have been formed around this topic including the Special Interest Group of the MAA on Quantitative Literacy (SIGMAA-QL) and the National Numeracy Network (NNN), both formed in 2004. In the ensuing years, numerous reports and courses have been developed centering on the topic of Quantitative Literacy [8, 14, 15, 16, 17, 22, 23, 24, 25, 26, 27]. As recently as 2010...
The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the o... more The infestation of prairie dog population with the deadly Yersinia Pestis has been recently the object of investigation of numerous biologists due to the potentially high risk of contamination of the human population. In the present paper we construct and analyze a model describing the interaction between the prairie dog population (as the host population) and the flea population (as the vector population) and derive the existence (under certain conditions impose to the main parameter) of an equilibrium that plays the role of a global attractor. Key–Words: Stability of Equilibria, Global attractor, Bifurcation.
Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. E... more Anticipating the number of hospital beds needed for patients with COVID-19 remains a challenge. Early efforts to predict hospital bed needs focused on deriving predictions from SIR models, largely at the level of countries, provinces, or states. In the United States, these models rely on data reported by state health agencies. However, predictive disease and hospitalization dynamics at the state level are complicated by geographic variation in disease parameters. In addition it is difficult to make forecasts early in a pandemic due to minimal data. However, Bayesian approaches that allow models to be specified with informed prior information from areas that have already completed a disease curve can serve as prior estimates for areas that are beginning their curve. Here, a Bayesian non-linear regression (Weibull function) was used to forecast cumulative and active COVID-19 hospitalizations for South Dakota, USA. As expected, early forecasts were dominated by prior information, which...
Wseas Transactions on Biology and Biomedicine, 2013
Thesis (Ph. D.)--University of Nebraska--Lincoln, 1997. Includes bibliographical references.
Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling w... more Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling will be presented. The first problem involves understanding the notion oscillation for Bezier surfaces, the freeform polynomial surfaces most common in Computer ...
Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling w... more Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling will be presented. The first problem involves understanding the notion oscillation for Bezier surfaces, the freeform polynomial surfaces most common in Computer ...
The article explores the efficacy of a Quantitative Literacy course in preparing students for pot... more The article explores the efficacy of a Quantitative Literacy course in preparing students for potential outcomes in traditional College Algebra course. It notes that the establishment of the course is aimed at providing students with alternative to college algebra, and facilitating their understanding on mathematics that they encounter in daily situations. Moreover, it indicates the significance of Quantitative Literacy course in elevating students' perceptions on the usefulness of mathematics.
WSEAS Transactions on Biology and Biomedicine
In this work we model the spread of sylvatic plague between two prairie dog colonies. The mathema... more In this work we model the spread of sylvatic plague between two prairie dog colonies. The mathematical model is one where a population of fleas transmits the plague to the host population of prairie dogs. Distance between the two colonies is examined as well as using insecticide to increase the death rates on the fleas that spread the disease between prairie dogs. Semi-analytical solutions for equilibria are derived using a perturbation series approach.
WSEAS Transactions on Biology and Biomedicine
In this work we model a pandemic where individuals are first infected with the influenza virus an... more In this work we model a pandemic where individuals are first infected with the influenza virus and later contract a secondary bacterial infection. The model uses a modified SIR approach with standard analytical and qualitative analysis. Theoretical questions are investigated concerning the proportion of the population to initially vaccinate for influenza, the proportion of the population to quarantine after being infected with influenza, and how improved treatments of bacterial infections all would play into reducing the net number of deaths.
Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling w... more Four unsolved problems that originate from research in Computer Graphics and Geometric Modeling will be presented. The first problem involves understanding the notion oscillation for Bezier surfaces, the freeform polynomial surfaces most common in Computer ...
Transport in porous media, 1998
Potential theory and Stokes' stream function techniques are used to investigate the flow str... more Potential theory and Stokes' stream function techniques are used to investigate the flow structure around the recirculation system developed by Gvirtzman and Gorelick (1992, 1993), which consists of an extraction well and a gallery (trench) for the recharge of ...