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A wirelessly networked opportunistic digital array radar (WNODAR) is an integrated ship wide digital phased array, where the array elements are placed at available open areas over the entire surface of the platform. The array elements are self-standing digital transmit/receive (T/R) modules with no hardwire connections other than prime power. All control and digitized signals are passed wirelessly between the elements and a central signal processor. This research investigates the problem of integrating the array elements through the design of a wireless synchronization and geolocation network. Phase synchronization of array elements is possible using a simple synchronization circuit. A technical survey of geolocation techniques was performed, and performance curves for the WNODAR operating under different seastate conditions were obtained. Analysis and simulation results suggest that a position location scheme to correct for dynamic effects of hull deflection is not absolutely necessary for an array operating at a VHF or lower UHF frequency. Finally, a design of the demonstration T/R module is proposed. Based on projected communication requirements, the full-scale WNODAR demands a 3.7 Gb/s data transmission rate. The multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) approach has been identified as a promising solution to achieve gigabit transmission rates.

Extensible Markup Language (XML) has had a revolutionary effect on information technology. Both business and government have adopted XML as the format of choice for information sharing. Business uses XML to leverage the full potential of the Internet for e-Commerce. The government wants to leverage the ability to share information across many platforms between divergent agencies. In particular, in August 2004, Executive Order (EO) 13356 called for improved sharing of terrorist information to protect Americans.[1] XML provides a way to format information so that it is interoperable. The economic benefit of sharing data and resources is apparent. Sharing information between government agencies will assist in national security. However, there is still a requirement to control the flow and state of data. Therefore, access controls must be used to ensure data and information are protected. This thesis asks whether it is possible to provide a survey and analysis of how industry is enforcing access control on XML data, information, and documents that could serve as a foundation for XML security architectures for the government.

We present the rationale for and the observational description of ASPECS: the ALMA SPECtroscopic Survey in the Hubble Ultra-Deep Field (UDF), the cosmological deep field that has the deepest multi-wavelength data available. Our overarching goal is to obtain an unbiased census of molecular gas and dust continuum emission in high-redshift (z > 0.5) galaxies. The similar to 1' region covered within the UDF was chosen to overlap with the deepest available imaging from the Hubble Space Telescope. Our ALMA observations consist of full frequency scans in band. 3 (84-115 GHz) and band. 6 (212-272 GHz) at approximately uniform line sensitivity (L'(CO) similar to 2 x 10(9) K km s(-1) pc(2)), and continuum noise levels of 3.8 mu Jy beam(-1) and 12.7 ae Jy beam(-1), respectively. The molecular surveys cover the different rotational transitions of the CO molecule, leading to essentially full redshift coverage. The [C II] emission line is also covered at redshifts 6.0 < z < 8.0. We present a customized algorithm to identify line candidates in the molecular line scans. and quantify our ability to recover artificial sources from our data. Based on whether multiple CO lines are detected, and whether optical spectroscopic redshifts as well as optical counterparts exist, we constrain the most likely line identification. We report 10 (11) CO line candidates in the 3mm (1mm) band, and our statistical analysis shows that < 4 of these (in each band) are likely spurious. Less than one-third. of the total CO flux in the low-J CO line candidates are from sources that are not associated with an optical/NIR counterpart. We also present continuum maps of both the band. 3 and band. 6 observations. The data presented here form the basis of a number of dedicated studies that are presented in subsequent papers.

We describe the first data release from the Spitzer-IRAC Equatorial Survey (SpIES); a large-area survey of similar to 115 deg(2) in the Equatorial SDSS Stripe 82 field using Spitzer during its "warm" mission phase. SpIES was designed to probe sufficient volume to perform measurements of quasar clustering and the luminosity function at z >= 3 to test various models for "feedback" from active galactic nuclei (AGNs). Additionally, the wide range of available multi-wavelength, multi-epoch ancillary data enables SpIES to identify both high-redshift (z >= 5) quasars as well as obscured quasars missed by optical surveys. SpIES achieves 5 sigma depths of 6.13 mu Jy (21.93 AB magnitude) and 5.75 mu Jy (22.0 AB magnitude) at 3.6 and 4.5 mu m, respectively-depths significantly fainter than the Wide-field Infrared Survey Explorer (WISE). We show that the SpIES survey recovers a much larger fraction of spectroscopically confirmed quasars (similar to 98%) in Stripe 82 than are recovered by WISE (similar to 55%). This depth is especially powerful at high-redshift (z >= 3.5), where SpIES recovers 94% of confirmed quasars, whereas WISE only recovers 25%. Here we define the SpIES survey parameters and describe the image processing, source extraction, and catalog production methods used to analyze the SpIES data. In addition to this survey paper, we release 234 images created by the SpIES team and three detection catalogs: a 3.6 mu m. only detection catalog containing similar to 6.1 million sources, a 4.5 mu m. only detection catalog containing similar to 6.5 million sources, and a dual-band detection catalog containing similar to 5.4 million sources.

When only whole years of age are recorded in survey data, children who experienced a birthday since the beginning of the school year may appear to be of school-age when they are not, or vice-versa. This creates an error in estimates of school participation indicators based on such data. This issue is well-known in education statistics, and several procedures attempting to correct for this error have been proposed. The present study critiques current practice and demonstrates that its limitations continue to confound educational research and high-stakes policy conclusions: speculative explanations have been proposed for what is actually a measurement artefact. An alternative adjustment strategy is proposed that coherently exploits all available information and explicitly indicates the remaining uncertainty. The application of the method is illustrated by a number of empirical case studies using recent household survey data. These examples demonstrate that the method is feasible, accurate, and that taking survey timing into account can significantly alter how these data are interpreted.

Thesis advisor: Larry H. Ludlow / Item Response Theory (IRT) is a contemporary measurement technique which has been used widely to model testing data and survey data. To apply IRT models, several assumptions have to be satisfied. Local item independence is a key assumption directly related to the estimation process. Many studies have been conducted to examine the impact of local item dependence (LID) on test statistics and parameter estimates in large-scale assessments. However, in the heath care field where IRT is experiencing greater popularity, few studies have been conducted to study LID specifically. LID in the health care field bears some unique characteristics which deserve separate analysis. In health care surveys, it is common to see several items that are phrased in a similar structure or items that have a hierarchical order of difficulties. Therefore, a Guttman scaling pattern, or a deterministic response pattern, is observed among those items. The purposes of this study are to detect whether the Guttman scaling pattern among a subset of items exhibit local dependence, whether such dependence has any impact on test statistics, and whether these effects differ when different IRT models are employed. The score-based approach - forming locally dependent dichotomous items into a polytomous testlet - is used to accommodate LID. Results from this dissertation suggest that the Guttman scaling pattern among a subset of items does exhibit moderate- to high-degree of LID. However, the impact of this special LID is minimal on internal reliability estimates and on the unidimensional data structure. Regardless of which models are employed, the dichotomously-scored person ability estimates are highly correlated with the polytomously-scored person ability estimates. However, the impact of this special LID on test information differs between Rasch models and non-Rasch models. Specifically, when only Rasch models are involved, test information derived from the LID-laden data is underestimated for non-extreme scores; whereas, when non-Rasch models are used, the opposite finding is reached –that is, LID tends to overestimate test information. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Research, Measurement, and Evaluation.

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Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 42-43. / by Rebecca Marta Henderson. / B.S.