Tourism patterns and determinants in the Great Lakes Region: populations,resources, roads,and perceptions

The Great Lakes Region of North America is attractive to tourists because of its vast areas of water, thousands of kilometers of shorelines, huge public forests, numerous parks, extensive commercial tourist facilities, interesting cities, and good highways. Most of the region's 65 million residents live in the southern industrial and agricultural portion so summer recreational travel is largely in a northerly direction to the lakes, shorelines, forests, and privately owned seasonal homes known as cottages. This travel involves international border crossings as Americans travel to rural and urban tourism destinations in Ontario, Canadians visit cities in the United States, and residents of both nations take circular tours around the Great Lakes. Each year, Ontario and neighboring American states spend a total of more than 20 million on tourism publicity trying to capture a larger share of the 40 billion spent in the region annually by tourists. However, the amount, nature, and patterns of tourist travel across the border are not well documented because of the lack of exit surveys.     

An assessment of fuzzy logic vessel path control

A fuzzy logic controller for ship path control in restricted waters is developed and evaluated. The controller uses inputs of heading, yaw rate, and lateral offset from the nominal track to produce a commanded rudder angle. Input variable fuzzification, fuzzy associative memory rules, and output set defuzzification are described. Two maneuvering situations are evaluated: track keeping along a specified path where linearized regulator control is valid; and larger maneuvers onto a specified path where nonlinear modeling and control are required. For the track keeping assessment, the controller is benchmarked against a conventional linear quadratic Gaussian (LQG) optimal controller and Kalman filter control system. The Kalman filter is used to produce the input state variable estimates for the fuzzy controller as well. An initial startup transient and regulator control performance with an external hydrodynamic disturbance are evaluated using linear model simulations of a crude oil tanker. A fully nonlinear maneuvering model for a smaller product tanker is used to assess the larger maneuvers     

Solar soft X-ray flare spectra from OSO-4

Solar flare spectral data, covering the wavelength range 0.7–8.5 Å, are derived from the NRL Bragg crystal spectrometers aboard OSO-4. A detailed analysis of the soft X-ray spectra for the 3b flare of 16 November 1967 (2140 UT) is presented, and it is found that electron temperatures derived from continua and emission lines are compatible with a two or more component plasma, differing in temperature by 6–10 × 10⁶K.     

Polarimetric analysis and modeling of multifrequency SAR signaturesfrom Gulf Stream fronts

Using airborne synthetic aperture radar data from the 1990 Gulf Stream Experiment, this paper investigates the polarization and wavelength dependence of radar signatures for narrow fronts with converging flows occurring within the Gulf Stream. The signal-to-background ratios of the cross-polarization backscatter return from a convergent front were found much higher than those of copolarization returns, when the flight path is crossing the front. However, a second convergent front, imaged at 45°, showed that the signal-to-background ratios are nearly equal for co- and cross-polarizations. A polarimetric procedure, which has been successfully used to measure terrain slopes and to generate elevation maps, is applied to the convergent front to explain the polarization and imaging geometry dependence of these radar responses. A theoretical modeling of radar modulation using an ocean wave model and a composite-Bragg scattering model, which incorporates the effect of breaking waves, was developed. Calculations with the model agree reasonably well with the radar measurements at various polarizations for three radar frequencies: P-band (68 cm in wavelength), L-band (24 cm), and C-band (5.7 cm)     

Sun-induced variations in time in the global positioning system

Sun-induced effects on the measurement and transfer of time information reported by orbiting satellites are reexamined. The problem of transforming the frequency of coherent radio signals to the Geocentric Inertial Coordinate frame (as required during the transfer of time information) involves an implicit, dependence on earth-sun-clock orientation that has been omitted, except in Very-Long-Baseline Interferometry (VLBI) studies. This known VLBI effect leads to an important second order Doppler effect. The effect explains systematic deviations between the time reported by satellites in the Global Positioning System (GPS) relative to Universal Time (UT) and can be used to improve existing bounds for the validity of the equivalence principle.     

Data model for system conceptualization in groundwater studies

Development of a conceptualization of a hydrogeologic system serves as the basis of groundwater modeling. While existing groundwater data models are designed to store groundwater system information, none is designed to capture its conceptual view. This study addresses this need by presenting a new object-oriented Conceptualization Groundwater Data Model that represents a groundwater system as a series of aquifer layers with defined aquifer properties and water boundary conditions. A case study is presented that develops the conceptual view of the groundwater system beneath Konza Prairie. This single conceptualization is used to support groundwater models across existing technologies of finite difference, finite element, and analytical element methods. While the models each employ different mathematics, data input files, and formats, all models are founded on the same conceptualization process that is represented using this new data model. The case study illustrates the data model's promise as an effective mechanism for groundwater system conceptualization and data storage, and utility for various groundwater computational models. This conceptualization of a groundwater data model suggests a new focus on incorporating system conceptualization into data model design.     

Nature and origin of nodular textures in anorthositic cumulates from the East Bull Lake Intrusion,Ontario, Canada

Summary Nodular anorthosite, containing rounded aggregates (nodules) of plagioclase set in a gabbroic to pyroxenitic matrix, is developed in constrictions (< 500 m wide) within the central and eastern parts of the Early Proterozoic East Bull Lake Intrusion, central Ontario, Canada. The nodules typically occur as spherical to ovoidal aggregates ranging from 1 cm to 14 cm in diameter. Larger nodules are physical agglomerations of smaller nodules that formed in isolation. Plagioclase core compositions for the nodules display little variation in anorthite content (An_68–75), indicating a homogeneous and nonfractionating parent magma during the initial stages of nodule development.The restricted occurrence of the nodular anorthosite is consistent with a model in which the nodules formed in response to elevated degrees of undercooling within dike-like constrictions in the proto-chamber. Undercooling resulted in the rapid nucleation and growth of plagioclase upon pre-existing plagioclase phenocrysts (disequilibrium crystallization). The resultant primary nodules then aggregated together forming secondary nodules, possibly through an agglomeration process involving a Mg-Fe-rich residual liquid. Migration of some of this relatively dense liquid out of the nodular anorthosite unit during the final stages of consolidation resulted in compaction and promoted the formation of large tertiary nodules.

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Zusammensetzung und Entstehung nodularer Texturen in anorthositischen Kumulaten von der East Bull Lake Intrusion, Ontario, Canada

Zusammenfassung Nodulare Anorthosite, die gerundete Aggregate (nodules) von Plagioklas in einer gabbroischen pyroxenitischen Matrix enthalten, kommen in beschränkten Bereichen (weniger als 500 m breit) in zentralen und östlichen Teilen der frühproterozoischen East Bull Lake Intrusion im zentralen Ontario, Canada, vor. Die Nodules liegen vorwiegend als kugelförmige bis ovoidale Aggregate vor, deren Durchmesser von 1 bis 14 cm schwankt. Größere Nodules sind aus Gruppen von aneinander gelagerten kleineren Nodules entstanden. Die Zusammensetzung von Plagioklaskernen in den Nodules zeigen geringe Variationen im Anorthit-Gehalt (An_68–78), und dies weist auf ein homogenes und nicht fraktioniertes Ursprungsmagma während der ersten Stadien der Nodule-Entwicklung hin.Das beschränkte Vorkommen des nodularen Anorthosits läßt sich durch ein Modell erklären, in dem die Nodules als Reaktion auf Unterkühlung innerhalb gangartiger Bereiche in der Proto-Magmenkammer entstehen. Unterkühlung resultierte in rascher Nukleation und im Wachstum von Plagioklas auf präexistierenden Plagioklaskristallen (Ungleichgewichts-Kristallisation). Die resultierenden primären Nodules verbinden sich dann und bilden sekundäre Nodules, möglicherweise durch einen Prozeß, der eine Mg-Fe-reiche Restschmelze involviert. Migration von einem Teil dieser relativ dichten Schmelze aus der nodularen Anorthosit-Einheit während der Endstadien der Verfestigung führte zur Kompaktion und erleichterte die Bildung von großen tertiären Nodules.

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With 4 Figures     

Energy cascades in the upper ocean

1 INTRODUCTION Wave-wave interactions play a key role in the evolution of the dynamics of upper ocean phenomena. Even though they conserve total wave energy, these interactions cause energy cascades to occur in which wave-energy is transferred at the surf…     

A velocity projection framework for inferring shallow water currents from surface tracer fields

To the extent that sea surface temperature and colors can be considered passive tracers, their motions can be tracked to estimate the current velocities, or a conservation equation can be invoked to relate their temporal variations to the velocities. We investigate the latter, the so-called tracer inversion problem, with a particular focus on (1) the conditions under which the problem can be rendered over-determined for least squares solutions, (2) the possibility of using the tracer conservation equation within the “velocity projection” framework to estimate subsurface current profiles in shallow coastal waters, and (3) the accuracy of the tracer inversion calculation in terms of the data resolution and noise. The velocity projection framework refers to relating surface motion, either measured directly or made visible by tracers, to the subsurface current motion through the equations of motion. The accuracy of the tracer inversion calculation is quantified in terms of the spatial and temporal resolution of the tracer distribution. In the presence of irreducible tracer noise, the accuracy of the inversion rapidly degrades, and it is shown that the inversion with velocity projection can help improve accuracy. The tracer inversion method developed in this study is applied to the satellite sea surface temperature data, and the velocity result is compared to the velocity measurements made with the shore-based HF Coastal Current Radar. The potential of improving the velocity estimation with the present approach is indicated.