775 research outputs found

    Maximum likelihood estimation of cloud height from multi-angle satellite imagery

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    We develop a new estimation technique for recovering depth-of-field from multiple stereo images. Depth-of-field is estimated by determining the shift in image location resulting from different camera viewpoints. When this shift is not divisible by pixel width, the multiple stereo images can be combined to form a super-resolution image. By modeling this super-resolution image as a realization of a random field, one can view the recovery of depth as a likelihood estimation problem. We apply these modeling techniques to the recovery of cloud height from multiple viewing angles provided by the MISR instrument on the Terra Satellite. Our efforts are focused on a two layer cloud ensemble where both layers are relatively planar, the bottom layer is optically thick and textured, and the top layer is optically thin. Our results demonstrate that with relative ease, we get comparable estimates to the M2 stereo matcher which is the same algorithm used in the current MISR standard product (details can be found in [IEEE Transactions on Geoscience and Remote Sensing 40 (2002) 1547--1559]). Moreover, our techniques provide the possibility of modeling all of the MISR data in a unified way for cloud height estimation. Research is underway to extend this framework for fast, quality global estimates of cloud height.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS243 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Global Music Perspectives: Music Outside the Western Canon in Local Schools

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    As a class, we are designing a research project for investigating how music teachers from counties in South-Central Pennsylvania use music from outside the Western canon (i.e. world music ). We are performing a qualitative study by interviewing k-12 music teachers from school districts in South-Central Pennsylvania. Teachers may choose to participate in a focus group interview with other teachers or in one-on-one interviews. The focus group interview will not exceed two hours and the one-on-one interviews will not exceed an hour. The interviews will be guided using a questionnaire (see attached), but the conversation may deviate from these questions at the discretion of the interviewer(s). We will transcribe these interviews to extract common thematic materials and relevant information. We will also compile a literature review of relevant peer-reviewed articles and use the data from said articles to expand upon our gathered information

    C4 Operations Optimization

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    The primary objective of the project chronicled in this report was to design a model that optimizes C4 operations. This model will optimize the options for processing both “crude C4” and “Cat BB” streams, taking the feed stream makeup, market pricings, and capacity constraints into account. Crude C4 streams contain butanes, butenes, and butadienes, while “Cat BB” streams are similar in makeup but do not include butadienes. It is assumed that the equipment for all unit operations is readily available. In addition, the plant will already have a baseload of feedstock that does not fully utilize all the equipment in the plant, which allows for the purchase of feedstock that could potentially be profitable. Available unit operations include Butadiene extraction, MTBE production, Metathesis, 1-Butene distillation, Skeletal Isomerization, Olefin Isomerization, and Alkylation. The model will be required to make choices about which unit operations to utilize based on the constraints input by the user. While the model will not directly produce revenue, it will allow the company to optimize processes within the plant, finding the most profitable situation. Thus, it will be possible to assess the program’s value based on its accuracy

    High speed video capture for mobile phone cameras

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    We consider an electromechanical model for the operation of a voice coil motor in a mobile phone camera, with the aim of optimizing how a lens can be moved to a desired focusing motion. Although a methodology is developed for optimizing lens shift, there is some concern about the experimentally-determined model parameters that are at our disposal. Central to the model is the value of the estimated magnetic force constant, Kf: its value determines how far it is actually possible to move lens, but it appears that, from the value given, it would not be possible to shift the lens through the displacements desired. Furthermore, earlier experiments have also estimated the value of the back EMF constant, Kg , to be roughly five times greater than Kf, even though we present two theoretical arguments that show that Kf = Kg: a conclusion supported by readily-available manufacturers’ data

    Modeling the growth of multicellular cancer spheroids in a\ud bioengineered 3D microenvironment and their treatment with an\ud anti-cancer drug

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    A critical step in the dissemination of ovarian cancer cells is the formation of multicellular spheroids from cells shed from the primary tumor. The objectives of this study were to establish and validate bioengineered three-dimensional (3D) microenvironments for culturing ovarian cancer cells in vitro and simultaneously to develop computational models describing the growth of multicellular spheroids in these bioengineered matrices. Cancer cells derived from human epithelial ovarian carcinoma were embedded within biomimetic hydrogels of varying stiffness and cultured for up to 4 weeks. Immunohistochemistry was used to quantify the dependence of cell proliferation and apoptosis on matrix stiffness, long-term culture and treatment with the anti-cancer drug paclitaxel.\ud \ud Two computational models were developed. In the first model, each spheroid was treated as an incompressible porous medium, whereas in the second model the concept of morphoelasticity was used to incorporate details about internal stresses and strains. Each model was formulated as a free boundary problem. Functional forms for cell proliferation and apoptosis motivated by the experimental work were applied and the predictions of both models compared with the output from the experiments. Both models simulated how the growth of cancer spheroids was influenced by mechanical and biochemical stimuli including matrix stiffness, culture time and treatment with paclitaxel. Our mathematical models provide new perspectives on previous experimental results and have informed the design of new 3D studies of multicellular cancer spheroids

    Growth of confined cancer spheroids: a combined experimental and mathematical modelling approach

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    We have integrated a bioengineered three-dimensional platform by generating multicellular cancer spheroids in a controlled microenvironment with a mathematical model to investigate\ud confined tumour growth and to model its impact on cellular processes
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