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Characterization of Plenoptic Imaging Systems and Efficient Volumetric Estimation from Plenoptic Data
Get PDFPlenoptic imaging is a rapidly growing field driven
by the ever-declining cost of imaging systems and the promise
of image focus, perspective, and depth of field manipulation
during post-processing. While plenoptic systems are often limited
to 2D image reconstruction and manipulation, plenoptic data
and reconstruction algorithms can be extended to volumetric
fields. An estimate of the imaged volume can be created by
generating a stack of 2D images, but such an estimate can easily
be dominated by image blur from neighboring focal planes.
Tomographic algorithms have been shown to be effective in
creating volumetric estimates from plenoptic data but are often
prohibitively slow. The research presented here shows that the
reconstruction is solvable through deconvolution. Unfortunately,
the observation model is not shift-invariant. However, with
appropriate transformations, the problem can be made shiftinvariant
so that deconvolution is a viable solution. Utilizing the
computationally efficient fast Fourier transform (FFT) allows the
reconstruction to be completed quickly while producing estimates
exhibiting significantly reduced blur compared to a simple focal
stack. This work describes a deconvolution algorithm designed
to reconstruct a 3D volume from a 2D plenoptic image. The
imaging system and refocusing algorithm are characterized with
respect to shift-variance in order to identify potential sources of
artifacts and propose potential mitigating steps. To demonstrate
the efficacy of the algorithm, experimental data is presented with
comparisons of the focal stack to the reconstructed volume
Alabama Performance Comparison of Peanut Varieties 2014
Get PDFCaption title. Cover title: Alabama Performance Comparison of Peanut Varieties 2014
Comparing Apples to Apples? Examining User Behavior for an Open-Access ETDs Collection vs. ProQuest
No full textMany institutions that maintain their own open-access repository for Electronic Theses and Dissertations (ETDs) also deposit ETDs into the vendor database ProQuest Theses & Dissertations. Since ETDs are the products of scholarly research, one might assume that both types of collections would have the same target audience and that their users would exhibit similar behavior and be seeking similar materials. One might also assume that (free) open-access collections would be more heavily used in developing countries while ProQuest would be more heavily used in so-called First World countries.
To examine these assumptions, this poster compares Google Analytics user statistics for a research university’s open-access ETDs collection created in DSpace with similar data obtained for that institution’s ETDs available from ProQuest. Comparisons are made for: (a) Overall collection use (including user visits, metadata page views, and ETD downloads data, as available); (b) Most-accessed materials (including fields of study and issue dates); (c) Users’ geographical locations (by country).Presente
Large increase in dissolved inorganic carbon flux from the Mississippi River to Gulf of Mexico due to climatic and anthropogenic changes over the 21st century
Get PDFIt is recognized that anthropogenic factors have had a major impact on carbon fluxes from land to the ocean during the past two centuries. However, little is known about how future changes in climate, atmospheric CO2, and land use may affect riverine carbon fluxes over the 21st century. Using a coupled hydrological-biogeochemical model, the Dynamic Land Ecosystem Model, this study examines potential changes in dissolved inorganic carbon (DIC) export from the Mississippi River basin to the Gulf of Mexico during 2010-2099 attributable to climate-related conditions (temperature and precipitation), atmospheric CO2, and land use change. Rates of annual DIC export are projected to increase by 65% under the high emission scenario (A2) and 35% under the low emission scenario (B1) between the 2000s and the 2090s. Climate-related changes along with rising atmospheric CO2 together would account for over 90% of the total increase in DIC export throughout the 21st century. The predicted increase in DIC export from the Mississippi River basin would alter chemistry of the coastal ocean unless appropriate climate mitigation actions are taken in the near future.Publishe
The Impact of Open Access on Collection Management
Get PDFOpen access (OA) is a relatively new concept in the long history of published scholarly communication. Although there were already some open access journals in 2002, many point to the Budapest Open Access Initiative (BOAI) held in that year as the beginning point of the “open access movement.” The BOAI called for freely available literature which permits “users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself.” 1 Since the BOAI, the open access movement has continued to grow and change, and in 2013 David Lewis predicted that over the next ten years, OA would “become the dominant mode for scholarly journal publishing” and recommended that academic libraries “continue to support open access initiatives: institutional deposit mandates; support for open access journals; or funding of open access author fees.” 2 Collection management was also expanding in the 2000s with the addition of access management: the need to facilitate effective and efficient access to electronic materials while still managing physical collections. 3 In 2011 Emilie Delquie asked if the philosophy of collection management was evolving from just collecting information to “‘hooking’ users up with information?” 4 This article examines if and how the integration of OA materials has changed collection and/or access management activities within academic libraries.PublishedYe
Bounded Complete Embedding Graphs, Extended Version
No full textThis is the extended version of my dissertation, "Bounded Complete Embedding Graphs." This version is presented in three parts, each in a separate file.
[Part 1] Bounded Complete Embedding Graphs
[Part 2] Extension A: The Superspectra of the Cohorts of Even Cycles, Revisited
[Part 3] Extension B: Satisfactory Divisors for the Dovetail Construction, Revisited
In the dissertation, we define bounded complete embedding graphs and bounded embedding graphs; establish that all bounded embedding graphs are bounded complete embedding graphs, but not conversely; show that all bounded complete embedding graphs are bipartite; and identify several infinite families of bounded complete embedding graphs.
One family of graphs receives particular attention: the cohorts of even cycles. The p-cohort of the 2k-cycle is the graph consisting of p vertex-disjoint copies of the 2k-cycle. In Chapter 4, we prove several results about the nature of the superspectrum of the p-cohort of the 2k-cycle; using these results, we have computed the exact superspectrum of this graph for all pairs of values of p and k such that p and k are both between 2 and 128. A few examples are given in Appendix A, along with the Python code we implemented to complete the necessary computations; the complete list of these superspectra is presented in the tables in Extension A.
Also in Chapter 4, we develop the Dovetail Construction, which allows us to build certain designs that are needed in order to obtain our bounded complete embedding graph results. Each time we apply this construction, we must verify its hypotheses, which include the existence, for certain numbers, of a divisor satisfying certain properties. We employ a short computer program to accomplish the necessary computations for these verifications; the Python code for this program is given in Appendix B, along with a complete listing of verification data for a few selected pairs of values of p and k. We have completed the verification computations for all pairs of values of p and k such that p and k are both between 2 and 128; full details are given for all pairs in the tables in Extension B
In-Service Teachers and their Information- Seeking Habits: Does Library Instruction Show a Relationship to Information-Seeking Habits for Professional Use?
Get PDFThis study describes an investigation of the information-seeking habits of in-service teachers specifically
in the context of seeking information for their professional practice. Data were also collected to investigate the
participants’ past participation in information literacy training via library instruction programs. Few publications have
been published on information-seeking habits of in-service teachers and fewer on those habits as they relate to finding
information for professional purposes. For this study an anonymous online survey was developed and disseminated to
teachers in eight school districts in a southern state. The results were analyzed and the findings indicated statistically
significant relationships between participation in library instruction and information-seeking habits. Additional data
were collected that indicated only a minority of survey respondents had participated in library instruction at the
academic libraries at their undergraduate institutions. The findings provided possible implications in regard to library
instruction in information literacy for students in teacher education programs.PublishedYe
Fast magnetosonic waves driven by shell velocity distributions
Get PDFUsing linear dispersion theory and particle-in-cell simulations, we explore the ion Bernstein instability driven by the shell-type ion velocity distribution which is related to the excitation of fast magnetosonic waves in the terrestrial magnetosphere. We first demonstrate a novel idea to construct the shell velocity distribution out of multiple Maxwellian ring-beam velocity distributions. Applying this technique, we find that the convergence of the linear theory instability can be achieved with only a moderate number of ring-beam components. In order to prove that such an approximation is legitimate and the linear theory instabilities evaluated are indeed valid, we use the exact shell distribution to carry out a number of one dimensional particle-in-cell simulations corresponding to multiple wave propagation angles adjacent to the direction at which the most unstable waves are expected to grow. The agreement between the linear dispersion analysis and the simulation results is generally very good: enhanced waves are organized along the linear theory dispersion curves in the frequency-wave number space, and relative wave amplitudes are ordered as the linear theory growth rates very well. However, the simulations show a few extra branches that are not expected from the linear dispersion analysis. A close examination of these extra branches suggests that they are not simulation artifacts and particularly related to the ring/shell-type distributions with large ring/shell speed (v>approximate to 1.5 v(A), where v(A) is the Alfven speed). In addition, our results show that substantial wave growth can occur at nonintegral harmonics of the proton cyclotron frequency at wave normal angles substantially far away from the perpendicular direction, which may provide an alternative explanation of the off-harmonic peaks of some fast magnetosonic waves observed in space.PublishedYe