Now showing items 1480-1499 of 15247

    • Calculus of variations solutions to problems of vertical flight

      Mason, Joseph David, 1937- (The University of Arizona., 1963)
    • The calendar heap: A new implementation of the calendar queue

      Sanchez, Paul J.; Ramsey, Terry, 1946- (The University of Arizona., 1989)
      A new implementation of the calendar queue is described in this thesis. The calendar queue as previously implemented depended upon the use of multiple linked lists for the control of queue discipline. In the calendar heap implementation, the heap has been used to replace the previous functions of the linked list. Testing of the claim of O(1) execution time for the calendar queue was done. Comparisons of execution times of the calendar queue and the calendar heap have been made. Descriptions of the implementation as well as the complete C code for the calendar heap are included.
    • Calibration and the decision variable partition model

      Smith, Mariam (The University of Arizona., 1981)
    • Calibration of a distributed land surface model for a semi-arid basin using remotely sensed data.

      Yatheendradas, Soni.; Gupta, Hoshin; Sorooshian, Soroosh (The University of Arizona., 2003)
      A meso-scale medium-resolution land surface model using the NCEP's NOAH code has been setup over the San Pedro basin in Arizona. The model is driven using the 50-year hydrologically balanced land surface data set developed at the University of Washington (UW), precipitation data from the PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks) system, and solar radiation influx from the University of Maryland's SRB (Surface Radiation Budget). The remotely sensed forcings are introduced in stages to explore the sensitivity on the simulation results to the remote sensing information. The model was calibrated, using the available remote sensing forcings, to ground observations of the turbulent heat fluxes and ground temperatures using multi-criteria calibration techniques. The simulation results for the distributed model using the default (uncalibrated) and the calibrated parameters are intercompared against each other and against the UW outputs. Results show the PERSIANN data substitution to be a major improving factor in the results in capturing the surface runoffs and the soil moisture diurnal variations because of its fmer sub-hourly temporal resolution as against the UW precipitation forcing which is basically at a daily temporal resolution. Separately, the default seasonal vegetation variation in the NOAH, i.e., constant greenness leaf area index (LAI) and variable greenness fraction (GF) was changed to the opposite case of constant GF and varying LAI using LAI data from the MODIS sensor. Visual inspection of the simulation results show the incompatibility between the NOAH and the MODIS LAI as per the MODIS LAI substitution method used in this study.
    • Calibration of an Infrared Laser Spectroscopy System for Measurement of High Precision Clumped Isotope Ratios in Carbonates

      Quade, Jay; Yanay, Nitzan; Dettman, David L.; Mcintosh, Jennifer (The University of Arizona., 2021)
      Measurements of 13C-18O clumping in CO2 derived from carbonates have greatly expanded paleothermometry research. However, measurement is slow and expensive using isotope ratio mass spectrometry (IRMS) and requires large sample sizes, 17O corrections, and gas-chromatograph cleanup. In order to overcome these limitations, we have developed a method for clumped isotope ratio measurements of CO2 by tunable infrared laser differential absorption spectroscopy (TILDAS). Our previously published results using gas samples demonstrate that measurements using this method are as precise with the best IRMS systems and surpasses typical IRMS measurements in several key respects, such as small sample size (15 μmol of CO2, 1.5 mg equivalent calcite), rapid measurement (precision of 0.01‰ within 20 minutes, 1 S.E.), and no isobaric interferences. Here we present results from measurements of CO2 derived from phosphoric acid digestion of carbonates at 90 ˚C, using a new, automated bellows sample introduction system. Two-hundred and thirty-nine gas samples and 468 carbonates have been tested, including in-house laboratory standards (Carrera marble and a synthetic standard), interlaboratory standards (ETH-1, ETH-2, ETH-3, ETH-4), and two natural samples. Synthetic carbonates, precipitated at controlled temperatures from 7 to 70 ˚C, have also been measured. In total 77 measurements of 12 synthetic samples were used to produce a linear temperature calibration:Δ638 = (0.0366±0.0031*106/T2) +0.1972±0.0334, R2=0.95429 This relationship is specific to our laser system and manual extraction line at present. The slope (0.0022±0.0002‰/°C) of the ∆16O13C18O–temperature calibration is slightly shallower than that predicted by theoretical calculations but is in agreement with several previous calibrations and successfully predicts the formation temperature of two natural samples. Calibration of the clumped isotope composition of carbonates on a new laser system is a work in progress. The TILDAS system is set to play an important role in advancing clumped isotope thermometry and stable isotope geochemistry as a whole.
    • Calibration of the Advanced Very High Resolution Radiometer

      Slater, P. N.; Grant, Barbara Geri, 1957- (The University of Arizona., 1989)
      This thesis describes the first calibration of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-11 satellite. Two methods were used to perform the calibration. Both methods relied on calibrated data from a high resolution sensor that passed over the target site at the White Sands Missile Range, New Mexico, on November 21, 1988. The first approach required ground reflectance and atmospheric optical depth data taken during overpass time. The second method relied on historical ground reflectance data and utilized standard atmospheric models. The calibration gains varied widely depending on which set of calibration offsets were used, but the agreement between the gains computed by the two methods was very close: approximately 1% in channel 1 and 2% in channel 2. This close agreement indicates that Method 2, which does not require the complexity and expense of field work, could be a viable option for future calibration efforts.
    • Calibration of the soil moisture accounting model using a gradient-type algorithm and analytic derivatives

      Hendrickson, Jene Diane,1960-; Sorooshian, Soroosh (The University of Arizona., 1987)
      In the pest, derivative-based optimization algorithms have not frequently been used to calibrate conceptual rainfall-runoff (CRR) models, partially due to difficulties associated with obtaining the required derivatives. This research applies a recently-developed technique of analytically computing derivatives of a CRR model to a complex, widely-used CRR model. The resulting least squares response surface was found to contain numerous discontinuities in the surface and derivatives. However, the surface and its derivatives were found to be everywhere finite, permitting the use of derivative-based optimization algorithms. Finite difference numeric derivatives were computed and found to be virtually identical to analytic derivatives. A comparison was made between gradient (Newton-Raphson) and direct (pattern search) optimization algorithms. The pattern search algorithm was found to be more robust. The lower robustness of the Newton-Raphson algorithm was thought to be due to discontinuities and a rough texture of the response surface.
    • Calibration of the soil moisture accounting model using the adaptive random search algorithm

      Weinig, Walter Theodore,1960-; Sorooshian, Soroosh (The University of Arizona., 1991)
      Random search techniques are being applied to a variety of non-linear parameter estimation problems. Random search for global optimization has the potential to overcome many of the problems associated with direct or pattern search techniques. In this research, an adaptive random search algorithm was applied to a conceptual rainfall-runoff model to study the efficiency of the algorithm in locating an optimum set of model parameters. The goal of the study was to determine how changes in internal algorithm control variables and objective functions affected the efficiency of the algorithm. Results indicated that the value of internal control variables did not have a strong influence on algorithm efficiency. Neither objective function gave demonstrably better results in calibration runs. Variability in results due to the random number seed was observed. Recommendations for further research are presented.
    • Calibration studies on a dual porosity unsaturated flow code (DCM3D)

      Bassett, R. L.; Fitzmaurice, Thomas Martin; Bassett, R. L. (The University of Arizona., 1994)
      A dual continuum, three-dimensional, isothermal ground-water flow code for unsaturated, fractured, porous media (DCM3D) was calibrated against two test cases; a laboratory block study and data from a monitored field location at the Apache Leap Research Site. Variably saturated water flow in the matrix as well as in the fracture system are described with two separate Richards' equation. Flow between the respective continua is simulated by means of a first order rate equation. Relative permeabilities are calculated using the van Genuchten characteristic relation. The formulation leads to a coupled system of nonlinear partial differential equations which are solved numerically using an integrated finite difference technique. Model calibrations were developed from existing data and supplemented with estimates of parameters not supported by previous research. Estimates included; initial conditions, fracture porosity, fracture van Genuchten parameters (a, m and Or) and the transfer factor. DCM3D proved able to reproduce flow behavior from both test cases. However, given the degrees of freedom, a unique solution was not found. Therefore, an evaluation on the conceptual understanding of flow in each test case was not possible. Sensitivity runs on fracture parameters showed fracture saturated intrinsic permeability and fracture porosity to be the most sensitive parameters relating to travel time. Increases in model complexity dramatically increased run times. Parameters which had the greatest effect on run time where the fracture a and fracture (}r.
    • The California rebound effect: An analysis of California's redistributive role in interstate migration

      Plane, David A.; Kirsch, Scott Lawrence, 1967- (The University of Arizona., 1991)
      California has historically been the primary geographic focus of westward migration in the United States. Trends of the 1960 and 1970s indicate that California's role in interstate migration is changing to that of a redistributor of population. In net terms, California is attracting in-migrants from the traditional core region of the Northeast and Midwest, and distributing population throughout the peripheral West. The emergence and development of these trends from 1935 to 1980 are analyzed through the demographic effectiveness of migration, a singly-constrained gravity model, and reverse gravity model mapping of relative interstate distances from California. International and historical interstate migration to California are also reviewed, as well as recent data on interstate migration during the 1980s. The phenomenon of California's redistributive role in interstate migration is discussed in relation to spatial shifts in economic and social functions, the role of search space, and a changing geographic ideal.
    • California wild and scenic rivers : an institutional analysis

      Stefan, Paul Anthony,1962-; Bradley, M. (The University of Arizona., 1991)
      Presented is an examination and analysis of a failed river protection institution in California from the 1960s to the early 1980s focusing on the California Wild and Scenic River Act of 1972. This act was designed to protect valued North Coast rivers, but its implementation failed under intense political pressure from two diametrically opposed and entrenched coalitions. This case study is primarily viewed under a lens of institutional analysis developed by Elinor Ostrom and the Indiana School of Public Choice. This method describes institutions as rules. When data allows, the river protection institution is enriched beyond rule based descriptions using other approaches which address relationships between individuals, organizations, and the structure of the institution. In conclusion, key lessons are identified which constitute important issues to policy-makers attempting to design or reform institutions. Also, methodologic questions raised during the analysis are discussed.
    • California's Bay Delta Dilemma: A Hydrologic, Legal, and Economic Investigation.

      Weber, Matthew August.; Maddock, Thomas J.; Glennon, Robert J.; Buras, Nathan (The University of Arizona., 1997)
      This is an effort to unify hydrology, water law, and economics for a coherent evaluation of the California Bay-Delta water conflict between environmental, agricultural, and urban interest groups. The integration of groundwater into state water resources planning is a crucial step in reforming California water policy. Groundwater and surface water are continuous elements of the water cycle. Unregulated groundwater use threatens surface flows, as well as being poor management of critical groundwater resources. State case law, local regulation, and federal law all have some ability to substitute for the lack of state groundwater code, but as yet these efforts are disparate and uncertain. Stronger state or federal management is essential. With water use permits for both groundwater and surface water, a more effective water marketing scheme could be employed to ease water rights restrictions and maintain water standards called for in the recent Bay- Delta compromise.

      Sleamaker, Robert Hayes. (The University of Arizona., 1982)

      Kulig, Judith Celene. (The University of Arizona., 1984)
    • Can a Women's Rural Livelihood Program Improve Mental Health? Evidence from India

      Rahman, Tauhidur; Kumar, Ashutosh; Aradhyula, Satheesh; Tronstad, Russ (The University of Arizona., 2016)
      There is a significant amount of literature documenting empirical linkages between socioeconomic status and mental health of individuals. While economic studies have found beneficial impacts of anti-poverty programs (e.g., micro-credit programs) on mental and emotional health, non-economic studies have documented the powerful roles of social capital in determining mental and emotional health. In this thesis, we study the impact of a large community-driven development (CDD) women's empowerment program, Jeevika, on mental health. JEEViKA is a rural livelihood program in Bihar, India, which promotes women's livelihood through a network of women's self-help group (SHG). Using data on a sample of 2300 SHG women from matched pairs of 66 high-exposure and low-exposure Jeevika villages, we estimate the causal impact of Jeevika on mental health. The results suggest that mental health improves with increasing age and among socially backward communities in high exposure JEEViKA villages. However, overall both the individual and village level analysis demonstrates no significant impact of JEEViKA on the mental health.
    • Can the Media Make or Break a Presidential Candidate?

      Westphal, Michael Gerhard (The University of Arizona., 1985)