Physical Sciences and Mathematics Commons^™

Astronaut Eva Exposure Estimates From Cad Model Spacesuit Geometry, Giovanni De Angelis, Brooke M. Anderson, William Atwell, John E. Nealy, Gary D. Qualls, John W. Wilson

Mathematics & Statistics Faculty Publications

Ongoing assembly and maintenance activities at the International Space Station (ISS) require much more extravehicular activity (EVA) than did the earlier U.S. Space Shuttle missions. It is thus desirable to determine and analyze, and possibly foresee, as accurately as possible what radiation exposures crew members involved in EVAs will experience in order to minimize risks and to establish exposure limits that must not to be exceeded. A detailed CAD model of the U.S. Space Shuttle EVA Spacesuit, developed at NASA Langley Research Center (LaRC), is used to represent the directional shielding of an astronaut; it has detailed helmet and backpack …

Steady State Simulation Of Ysz Intermediate-Temperature Fuel Cell, Zi-Jing Lin, Ye Gu, Xiao-Hua Zhang

Journal of Electrochemistry

With a coupled 2D electrochemical and thermal modeling software, the characteristics of the steady state operation of the intermediate-temperature fuel cell with thin yttria-stabilized zirconia(YSZ) electrolyte was analyzed. The parameters of I-V equation were obtained from fitting the experiment results and the choice of grid points was determined by balancing the accuracy requirement and computational efficiency. The temperature fields at different operation circumstances such as flow designs, material choices for interconnect, were examined. The dependences of the output power and cell efficiency on the operating voltage at different temperatures were studied. Based upon the analysis of the temperature profile, it …

Time Domain Probabilistic Risk Assessment:, George H. Baker, Charles T. C. Mo

George H Baker

For critical facilities, survivability and reconstitution in stressful environments generated by electromagnetic transients, sabotage, terrorist activity, military conflict, or Murphy’s laws are issues of concern. Critical fixed facilities are likely to be functionally complex and their system-wide failure probabilities, modes, and consequences are often not obvious. To analyze and quantify survivability, existing probabilistic risk assessment tools usually provide a “snapshot” of failure modes at a single point of time for certain initiating conditions. Likewise, elaborate physics models developed to treat weapons effects on structures and individual functional components compute effects at a single time point.

We have developed a tool …

Comparison Of Observed And Simulated Grow-Finish Swine Performance Under Summer Conditions, Larry W. Turner, Thomas C. Bridges, Richard D. Coffey, Richard S. Gates, Gary R. Parker, Tami M. Brown-Brandl, Douglas G. Overhults

Biosystems and Agricultural Engineering Faculty Publications

As a part of a National Pork Producers Council educational program, our research and extension team at the University of Kentucky was linked with an independent commercial swine producer to test the NCPIG model against observed commercial on-farm data. This experience provided improved information for model development as well as increased producer insight into the data input needs and potential benefits of modeling. Detailed production information comparisons between the NCPIG model and producer data are presented for summer time conditions to assess the validity of the NCPIG model for simulation of grow-finish swine performance. Results demonstrated that the NCPIG model …

Green And Ampt Infiltration With Redistribution, Fred L. Ogden

Fred L. Ogden

Distributed, physically based watershed and irrigation advance models require robust infiltration estimation capabilities. The empirical Green and Ampt (GA) equation of infiltration is a popular method for estimating infiltration. The GA parameters have physical basis and considerable prior research has focused on relating these parameters to soil textural classification. However, the original GA method is limited in that it is applicable only for a single ponding period. An explicit Green and Ampt redistribution (GAR) technique is developed herein to estimate interstorm redistribution of soil water and allow multiple ponding simulations using the GA methodology. Soil water redistribution during interponding periods …

A Direct, Approximate Solution To The Modified Green-Ampt Infiltration Equation, Puneet Srivastava, Thomas A. Costello, Dwayne R. Edwards

Biosystems and Agricultural Engineering Faculty Publications

Accurately predicting the rainfall-runoff process is of vital importance for water quality models as well as for correct design of various types of hydraulic structures. This article presents a method of describing the cumulative infiltration process as an explicit function of time using an approximation to the modified Green-Ampt equation given by Mein and Larson (1971). The resulting equation is helpful in predicting cumulative infiltration and therefore infiltration capacity for computer simulation models. The proposed method takes about 50% less time than the usual iterative technique for the same degree of accuracy. The maximum error due to approximation was 1% …

Application Of Simplified Phosphorus Transport Models To Pasture Fields In Northwest Arkansas, Dwayne R. Edwards, C. T. Haan, Andrew N. Sharpley, John F. Murdoch, Tommy C. Daniel, Philip A. Moore Jr.

Biosystems and Agricultural Engineering Faculty Publications

Runoff transport of phosphorus (P) is often predicted from simple equations with parameters determined from data applicable primarily to row-cropped and fallow cover conditions. The applicability, accuracy, and precision of such P transport prediction equations under pasture situations are less well defined. The objectives of this study were to determine parameters of simplified runoff P transport equations for pasture fields and to assess the accuracy and precision of the equations. Runoff, sediment yield, soluble P transport, and particulate P transport data were collected from four pasture fields in northwestern Arkansas. Runoff event enrichment ratios and extraction coefficients were computed, and …

Selected Legal Issues Relating To Application Of American Water Development, Inc., Case No. 86 Cw 46, Water Division No. 3, Colorado, Charles B. White

Uncovering the Hidden Resource: Groundwater Law, Hydrology, and Policy in the 1990s (Summer Conference, June 15-17)

13 pages.

Compact – A Reclamation Soil Compaction Model Part Ii. Sensitivity Analysis And Applications, Ronald L. Bingner, Larry G. Wells

Biosystems and Agricultural Engineering Faculty Publications

COMPACT, a physically based, event-oriented compaction model, was developed as a management or research tool to evaluate the influence of a surface mining system on compaction of soil material during reclamation. Two systems of area mining reclamation operations were simulated by COMPACT. The first system involved scrapers and bulldozers and the second also included trucks. Scrapers or trucks were used to pick up and deposit the soil material. Bulldozers were then used to shape the site for reclamation. The simulated results were compared with measured results and show how equipment patterns and soil parameters can affect overall soil compaction. This …

Compact – A Reclamation Soil Compaction Model Part I. Model Development, Ronald L. Bingner, Larry G. Wells

Biosystems and Agricultural Engineering Faculty Publications

A physically based, event oriented soil compaction model, known as COMPACT, was developed as a management or research tool to evaluate the effect of surface mining systems on compaction of soil material during reclamation. Simulation of compaction throughout the soil profile at a surface mining reclamation site requires information describing how equipment moves on the site. The compaction processes that are caused by vehicles throughout the soil profile are described by applying the pressure distribution of the surface contact area of a tire or track to determine stresses in the soil profile. A virgin compression curve is then used to …

Generalized Linear Inversion Using Tau-P Forward Modeling, Stephen Dade Walker

Graduate Theses

The Generalized Linear Inversion (GLI) method is used in conjunction with a tau-p forward model to successfully perform inversions of test and real-data examples. All data examples used are one-dimensional velocity profiles that represent several different cases. The stability of the technique is demonstrated in all the test-data sets. The use of simple models and wel1-control 1ed test data results in a minimum of iterations of the inversion process. Different levels of perturbation of the model and test-data examples are used to reveal insight into the robust nature of the inversion.

A Method Of Modeling Multirate Two-Dimensional Recursive Digital Filters Author, Albert P. Gerheim

Electrical & Computer Engineering Theses & Dissertations

This dissertation presents a method of modeling two dimensional sampled data systems with two sampling rates in each dimension. This methodology is applied to the problem of synthesizing two dimensional velocity filters using one dimensional prototypes and multirate concepts.

The modeling method includes the replacement of scalar z-transforms of signals by vectors of polynomials, and the replacement of scalar z-transforms of impulse responses by matrices of polynomials.

The synthesis of velocity filters is accomplished through the use of coordinate transformations in the z-transform domain which skew the ω₁ -ω₂ axes on the unit bidisc. The filters synthesized using …