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A numerical study of coastal stratus cloud in a two-dimensional meso-scale modelLee, Tae Young 01 November 1983 (has links)
A two-dimensional numerical mesoscale model, which ic1udes
radiative and turbulent transfers, has been constructed to study the
formation, development and dissipation of coastal stratus cloud
under an inversion. In the model, the delta-Eddington and emissivity
approximations are used for the solar and thermal radiative
transfers, respectively. K-theory parameterization is adopted for
the turbulent transfer. Ground surface temperature and moisture are
predicted using the methods of Deardorff (1977, 1978). This model
is applied to a domain which extends 180 km into sea and 240 km
inland horizontally and about 2 km from the earth1s surface vertically.
A bare, flat soil surface is assumed.
As a prelude to the study of the stratus cloud, sea breeze
circulations with and without a temperature inversion have been
investigated. The model without an inversion yields speeds of the
sea breeze front which are close to the values that have been
observed under insolation and other meteorological conditions
similar to those used in the model. The presence of an inversion
causes the depth of sea breeze circulation to be shallower and its
inland penetration during the evening hours to be weaker compared to
the case without inversion; however, the basic structure of the sea
breeze circulation is unaffected by the inversion.
The model has been used to study the growth, development and
dissipation of stratus cloud under an inversion in the west coast
region of the United States. The effects of large scale motions on
these processes have also been examined. Cloud parameters such as
the times of initial formation and of dissipation inland, the maximum
distance of inland penetration, the maximum liquid water path
and the cloud-top height are affected in the presence of such large
scale motions; for example, both the maximum liquid water path and
the cloud-top height are appreciably enhanced - by about a factor of
two - when large scale westerly winds (U[subscript g]=5mfs, V[subscript g]=0) are present
compared to the case when U[subscript g]=V[subscript g]=0. The cloud parameters
predicted by the model are in close correspondence with existing
observations in southern California.
It is found that the sea breeze circulation is not appreciably
affected by the presence of moderate amounts of stratus cloud.
While advection plays a dominant role in the horizontal development
of the stratus cloud inland, radiative processes (cooling
and heating) are observed to govern the vertical growth and dissipation
of the cloud layer. Vertical growth is influenced by the rate
of radiative cooling at cloud-top. Because of the combined effects
of solar and surface heating, the stratus inland is observed to
dissipate more rapidly during the morning hours than the cloud over
the ocean where surface heating is minimal. / Graduation date: 1984
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Specification of local surface weather elements from large-scale general circulation model information, with application to agricultural impact assessmentWilks, Daniel S. 26 November 1986 (has links)
A procedure for model-assisted climate impact assessment is
developed. The approach combines data from observations and
atmospheric general circulation models (GCNs), and provides the basis
for a potentially valuable means of using information derived from
GCMs for climate impact assessments on local scales.
The first component of this procedure is an extension of the
'climate inverse' method of Kim al. (1984). Daily mesoscale
temperature and precipitation values are stochastically specifed on
the basis of observational data representing the average over an area
corresponding to a GCN grid element. Synthetic local data sets
generated in this manner resemble the corresponding observations with
respect to various spatial and temporal statistical measures.
A method for extrapolation to grid-scale 'scenarios' of a changed
climate on the basis of control and experimental integrations of a
GCM, in conjunction with observational data, is also presented. The
statistical characteristics of daily time series from each of these
data sources are portrayed in terms of the parameters of a
multivariate time-domain stochastic model. Significant differences
between the model data sets are applied to the corresponding
parameters derived from the observations, and synthetic data Bets
representing the inferred changed climate are generated using
Monte-Carlo simulations.
The use of the procedure is illustrated in a case study. The
potential climatic impacts of a doubling of atmospheric carbon dioxide
concentrations on three important North American grain cropping
regions is investigated using two 'physiological' crop models.
Although the specific results must be interpreted with caution, they
are moderately optimistic and demonstrate possible means by which
agricultural production may adapt to climatic changes. / Graduation date: 1987
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The energy budget and mass balance of the OSU atmospheric general circulation model viewed in terms of constant pressure layersOh, Jai-Ho 04 October 1983 (has links)
Graduation date: 1984
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Stochastic analysis of the nonlinear response transition behavior of an ocean systemYuk, Dongjun 16 February 2001 (has links)
The nonlinear response of an ocean system subjected to random excitations can exhibit very complex dynamic behaviors including jump phenomena and coexistence of attractors. In this study, the stochastic system response behavior of a simple (Duffing) oscillator under narrow-band random excitations is first examined in the subharmonic resonance region. A semi-analytical procedure based on the nonlinear response characteristics of the corresponding deterministic system is developed to derive the response transition probabilities within individual attraction domains and among finite attraction domains under the assumptions of stationarity and Markov process. Overall response amplitude probability distributions are obtained by applying the Bayes formula to the two different types of response transition probability distributions.
To validate the prediction capability of the semi-analytical method, numerical simulation of the responses of the Duffing system are generated and statistical characteristics of the response behavior are compared with prediction results. It is shown that the semi-analytical procedure provides more accurate predictions than other approximate methods available in the literature. A parametric study on the effects of variations in excitation intensity and degree of narrow-bandedness is conducted. Results confirmed that the nonlinear response characteristics including jump phenomenon and co-existence of attraction domains are preserved under narrow-band random excitations.
The semi-analytical prediction method developed above is then applied to analyze the stochastic response behavior of a nonlinear mooring system subjected to random ocean waves. For modeling of the structural system, a nonlinear�� structure, nonlinearly-damped (NSND) model is employed and a reverse multiple�� input/single-output technique is applied to identify the system coefficients. To verify the accuracy and capability of the semi-analytical method in predicting the complex behaviors of the nonlinear mooring system, analytical predictions are compared with experimental results and numerical simulations. System response amplitude probability distributions predicted by the semi-analytical procedure are shown to be in good agreement with experimental and simulation results. / Graduation date: 2001
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Essays on applied microeconomicsNoh, Dong Woon 28 October 2002 (has links)
This dissertation addresses three topics on applied microeconomics. First, we investigate issues of market power and tax incidence in the U.S. brewing industry. Since alcohol consumption can be addictive, we derive a structural econometric model of addiction from a dynamic oligopoly game. This model identifies the degree of market power in a dynamic setting and allows us to test the hypothesis that federal tax incidence differs from state excise tax. Results indicate that beer producers have a modest market power and an increase in federal excise tax is more effective to reduce consumption than state excise taxes. Second, we estimate the effect of sulfur dioxide (S0���) emissions regulations on the productivity growth and opportunity cost of 261 phase I generating units. The Clean Air Act Amendment (CAAA) of 1990 required units to reduce emissions to 2.5 pounds per mmBTU fuel input in the phase I period (1995-99). We calculate Luenberger productivity indicators using directional technology distance function for 209 units in 1990-1999. There is more potential to reduce pure technical inefficiency since it is the main source of inefficiency in phase I period. Productivity declined, hut it i not significantly different from the productivity growth of pre-phase I. So environmental policy is successful to reduce SO��� emission without sacrificing productivity growth. Opportunity cost declined, but the opportunity cost of scrubber and "other" strategy increase. Third, we estimate the regulatory effect on strategy choice of 257 phase I units using multinomial logit model. We assume behavioral cost is a function of shadow input prices, output, SO��� emissions and regulatory variables. Results suggest regulation significantly affect choices. Units located in high-sulfur coal states are more likely to choose scrubber, allowance or "other" strategy through shadow capital price effect. Allowance trade and sales restriction negatively affect allowance, scrubber or fuel switch strategy. Non-private units are more likely to choose allowance strategy while private units are likely to choose less uncertain scrubber and fuel switch. Units subject to stringent local regulation are more likely to choose "other" strategy and scrubber and units with substitution/compensation boilers are more likely to choose allowance and "other" strategies. / Graduation date: 2003
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Partitioning of rare earth and high field strength elements between pargasitic amphibole and silicate meltsHilyard, Mark D. 29 May 1997 (has links)
Graduation date: 1998
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Strategic modeling of sustainable food supply systemsJorgensen, Jane 07 April 1997 (has links)
Graduation date: 1997
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Dynamics of the nearshore wave bottom boundary layerFoster, Diane Lyn 13 June 1996 (has links)
This thesis presents an examination of the nearshore wave bottom boundary layer
under conditions of significant sediment response. Using both field observations and
simple models, the response of the bottom boundary layer to random waves is shown to
have a complex behavior. First, the linearized wave bottom boundary layer governing
equation is solved with a transformation of the cross-shore velocity to a distorted spatial
domain, resulting in an analytic expression for the temporal and vertical structure of the
cross-shore velocity under an arbitrary wave field. Model predictions of the bed shear
velocity are in good agreement with laboratory measurements. The model is limited by
assuming zero velocity at a fixed bed and that turbulence generation is solely due to bottom
shear.
Next, a comprehensive set of near bed cross-shore velocity, sediment suspension,
and bed elevation observations, collected in 2 m water depth on the North Carolina coast,
are presented. The observations show a cross-shore velocity structure which decays with
increasing proximity to the bed as predicted by simple theory. Bottom shears based on
rms amplitude decay and time-averaged phase shifts are lower than model predictions and
may be indicative of more rapid mixing of momentum than assumed in the above model.
Also, frequency-dependent estimates of the phase and amplitude vertical structure show a
nonlinear response of the wave bottom boundary layer over the incident band. Through
most flow phases, estimates of turbulent kinetic energy increase linearly from the bed,
however under large wave crests, enhanced turbulence levels are observed and are well
correlated to active sediment suspension events. Estimates of dissipation rates are
significantly less than those observed in an actively breaking surf zone wave, and
significantly greater than those observed in ocean boundary layers, and continental shelf current boundary layers. Finally, an Oregon coast field experiment showed an intermittent high frequency
velocity variance structure which was correlated to suspended sediment events. A linear shear instability analysis determined that during the period of flow reversal there exists a potential for generating turbulence due to shear instabilities of the vertical structure of cross-shore velocity. / Graduation date: 1997
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Reliability centered prediction technique for diagnostic modeling and improvementMurphy, Michael D., 1965- 14 November 1995 (has links)
Design phase decisions based on diagnosability lead to lower system costs and, in turn, higher quality products by means of reducing maintenance time and increasing system reliability. A case for diagnosability is presented. Functions of diagnosability are expounded upon including life cycle costs, statistical analysis, and design criterion to emphasize the necessity of diagnosability analysis early in the design phase. A diagnosability prediction metric is developed for system modeling of component failure rates and unjustified removals. The metric emphasizes ambiguity of system component indications as well as system structure. The metric is evaluated using historical data from the bleed air control system (BACS) on the Boeing 737-300. Seven design changes are suggested based on improving system diagnosability by changing component functions, modifying indications, and adding or changing sensors. The resulting designs are compared via Boeing's life cycle cost mechanism, DEPCOST model, based on cost improvements. It is shown that system improvements based on this prediction technique will increase the quality of a product since increased diagnosability decreases life cycle costs. / Graduation date: 1996
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Inner-shell lifetimes of small gas-phase moleculesCoville, Mary 16 January 1996 (has links)
Graduation date: 1996
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