3,199 research outputs found
Estimates of growth and comparisons of growth rates determined from length- and age-based models for populations of purple wrasse (Notolabrus fucicola)
Growth of a temperate reefa-ssociated fish, the purple wrasse (Notolabrus fucicola), was examined from two sites on the east coast of Tasmania by using age- and length-based
models. Models based on the von Bertalanffy growth function, in the standard and a reparameterized form, were constructed by using otolith-derived age estimates. Growth
trajectories from tag-recaptures were used to construct length-based growth models derived from the GROTAG model, in turn a reparameterization of the Fabens model. Likelihood
ratio tests (LRTs) determined the optimal parameterization of the GROTAG model, including estimators of individual growth variability, seasonal growth, measurement error,
and outliers for each data set. Growth models and parameter estimates were compared by bootstrap confidence intervals, LRTs, and randomization tests and plots of bootstrap parameter estimates. The relative merit of these methods for comparing models and parameters was evaluated; LRTs combined with bootstrapping and randomization tests provided
the most insight into the relationships between parameter estimates. Significant differences in growth of purple wrasse were found between sites in both length- and age-based models. A significant difference in the peak growth season was found between sites, and a large difference
in growth rate between sexes was found at one site with the use of length-based models
Archival of Seasat-A satellite scatterometer data merged with in situ data at selected, illuminated sites over the ocean
A large data base of Seasat-A Satellite Scatterometer (SASS) measurements merged with high-quality surface-truth wind, wave, and temperature data has been documented. The data base was developed for all times when selected in situ measurement sites were within the SASS footprint. Data were obtained from 42 sites located in the coastal waters of North America, Australia, Western Europe, and Japan and were assembled by correlating the SASS and surface-truth measurements in both time and distance. These data have been archived on a set of nine-track 6250 bpi ASCII coded magnetic tapes, which are available from the National Technical Information Service
Method of identifying clusters representing statistical dependencies in multivariate data
Approach is first to cluster and then to compute spatial boundaries for resulting clusters. Next step is to compute, from set of Monte Carlo samples obtained from scrambled data, estimates of probabilities of obtaining at least as many points within boundaries as were actually observed in original data
A computer program for a line-by-line calculation of spectra from diatomic molecules and atoms assuming a Voight line profile
Computer program predicts the spectra resulting from electronic transitions of diatomic molecules and atoms in local thermodynamic equilibrium. The program produces a spectrum by accounting for the contribution of each rotational and atomic line considered
Deployable reflector antenna performance optimization using automated surface correction and array-feed compensation
Methods for increasing the electromagnetic (EM) performance of reflectors with rough surfaces were tested and evaluated. First, one quadrant of the 15-meter hoop-column antenna was retrofitted with computer-driven and controlled motors to allow automated adjustment of the reflector surface. The surface errors, measured with metric photogrammetry, were used in a previously verified computer code to calculate control motor adjustments. With this system, a rough antenna surface (rms of approximately 0.180 inch) was corrected in two iterations to approximately the structural surface smoothness limit of 0.060 inch rms. The antenna pattern and gain improved significantly as a result of these surface adjustments. The EM performance was evaluated with a computer program for distorted reflector antennas which had been previously verified with experimental data. Next, the effects of the surface distortions were compensated for in computer simulations by superimposing excitation from an array feed to maximize antenna performance relative to an undistorted reflector. Results showed that a 61-element array could produce EM performance improvements equal to surface adjustments. When both mechanical surface adjustment and feed compensation techniques were applied, the equivalent operating frequency increased from approximately 6 to 18 GHz
A Software Architecture for Adaptive Modular Sensing Systems
In this thesis, a novel software architecture and knowledge representation scheme is described that facilitates the combination and reconfiguration of modular sensor and actuator components, termed transducer interface modules (TIMs), to produce flexible modular sensor systems. Each TIM provides a core sensing or actuation functionality. A composite sensor is able to automatically determine its overall geometry and assume an appropriate collective identity, and if reconfigured, may then assume a different identity to match its new geometry. In current practice, a fixed combination of sensors and actuators is typically utilized, and is tailored to a specific application. Such systems cannot be cheaply or quickly reconfigured to handle a change in process requirements. Domains that may benefit from easily reconfigurable modular sensing systems include flexible inspection, mobile robotics, surveillance, and even space exploration. The software architecture is distributed, and is comprised of six layers where the implementation of each layer is encapsulated from the layer above, to which it provides service. The use of a distributed and layered architecture promotes scalability, mitigates against a single point of failure, and enables each layer to be easily implemented, modified, and debugged independently of the others. The modularization of the software architecture is further facilitated through the utilization of a pre-emptive real-time operating system, which enables the concurrent execution of the various software components specific to the architecture that implement the services provided within most of its layers. Among the layers comprising the software architecture is a virtual machine layer, which implements a lightweight, architecture-specific version of Sun Microsystems’ Java Virtual Machine that runs on top of the real-time operating system. The integration of a virtual machine enables the platform-independent template algorithms utilized at the composition layer to be written once and executed on any TIM irrespective of its underlying hardware architecture. These template algorithms are unique to this software architecture and provide intelligence to a set of heterogeneous TIMs, enabling them to collaborate and behave as a single entity termed a logical module. The evaluation of the software architecture consists of performing multiple runs of two tests in which select sensors and actuators are associated with TIMs that are then allowed to interact in order to form a logical entity. The first test evaluates the behaviour of a logical module in which the constituent TIMs interact entirely through wireless communication. The second test evaluates the behaviour of a logical module in which the constituent TIMs are physically connected in various orientations, and interact through both wireless communication as well as through their physically connected faces. In both tests, correct behaviour was exhibited. However, the performance and scalability of the architecture was somewhat restricted by the limited processing and memory resources present in the current implementation of the TIMs. The design of the software architecture facilitates easy portability between embedded platforms and scales with increasing hardware capability. Therefore, utilization of future TIM hardware variations possessing increased processing and memory resources will reduce the latencies introduced throughout the architecture and lead to tangible improvements in its performance
Improved self-consistency for SCED-LCAO.
In this document I describe a novel implementation of the generalized bisection method for finding roots of highly non-linear functions of several variables. Several techniques were optimized to reduce computation time. The implementation of the bisection method allows for the calculation of heterogeneous systems with SCED-LCAO, since derivative-based methods often fail for these systems. Systems composed of Gallium and Nitrogen are currently receiving much interest due to their behavior as semi-conductors and their ability to form nano-wires. The methods developed here were employed to create a set of SCED-LCAO parameters for homogeneous Gallium and heterogeneous Gallium Nitride systems. These parameters were shown to provide SCED-LCAO with predictive power for future Gallium Nitride systems
Participation in Extracurricular Activities and the Relationship to Academic Achievement and School Attendance Among High School Seniors
This study examines the relationship between participation in extracurricular activities and the variables of school attendance and academic achievement. The population for the study was the 1994-95 graduating class in the First Tennessee Development District high schools. The definition of extracurricular activities was expanded to include the employment of students. The relationships were examined through Pearson Product Moment correlations and by way of multiple regression. A total of 575 students from thirteen high schools made up the sample for this study. Schools were classified into three size categories and proportionally selected in order to accurately represent the population. Selected students responded to a survey instrument in order to provide the information to be analyzed. Demographic information concerning race, gender, and estimated family income was gathered. Respondents were also asked to provide the number of absences during the current year and current cumulative grade point average. The remaining portion of the survey contained a list of thirty-seven activities typically sponsored by high schools. Students provided information regarding the amount of time per week and the time frame of participation for any activity in which they participated. Space was allotted for respondents to provide the same information for activities not listed. A significant relationship was found between involvement in extracurricular activities and both school attendance and academic achievement. Results showed that as involvement in extracurricular activities increased, school attendance and academic achievement improved. This was true for two definitions of involvement. Results for employment differed. As involvement in employment increased, school attendance and academic achievement declined
An Analysis of the Marketing Practices of Selected North Dakota Banks
This thesis describes and analyzes the marketing practices of selected banks in North Dakota. The data were obtained principally from a survey of banks in North Dakota. A mail questionnaire was sent to all banks with over 20,000,000 appear to be most knowledgeable about marketing. These banks usually have one person solely responsible for the management of the bank\u27s marketing activities. Only twenty-eight percent of the respondent banks had written marketing plans. In comparison sixty-three percent of the banks budgeted for their marketing effort.
North Dakota banks, in general, placed great importance on advertising as a marketing activity. Most respondent banks ranked newspapers as their most important medium as well as their most effective medium
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