Browsing by Author "Wang, Lu"

Now showing 1 - 5 of 5
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    A statistical model for removing inter-device differences in spectroscopy
    (Optical Society of America, 2014) Wang, Lu; Lee, Jong Soo; Lane, Pierre; Atkinson, E. Neely; Zuluaga, Andres; Follen, Michele; MacAulay, Calum; Cox, Dennis D.
    We are investigating spectroscopic devices designed to make in vivo cervical tissue measurements to detect pre-cancerous and cancerous lesions. All devices have the same design and ideally should record identical measurements. However, we observed consistent differences among them. An experiment was designed to study the sources of variation in the measurements recorded. Here we present a log additive statistical model that incorporates the sources of variability we identified. Based on this model, we estimated correction factors from the experimental data needed to eliminate the inter-device variability and other sources of variation. These correction factors are intended to improve the accuracy and repeatability of such devices when making future measurements on patient tissue.
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    Application of nanoparticles in downhole detection
    (2014-12-11) Wang, Lu; Tomson, Mason B.; Bedient, Philip B.; Tour, James M.
    The revolution of nanotechnology leads to the increasing application of nanoparticles in many industry fields. Nanoparticles, due to the small size, are supposed to transport through subsurface formation without breaking rock structure and thus have received tremendous attention1-12. Nanoparticles also have many unique physical, chemical and optical properties, which are not found in bulk samples with the same chemical composition. Such nanoparticles, therefore, may be attractive as candidates to detect the chemical and physical properties underground, by directly interact with the important targets. Because of the increasing energy demands, it becomes more desirable to develop new technology to detect the downhole conditions. In this paper, nanoparticles possessing functionalized carbon black cores and treated polyvinyl alcohol addends was designed as carrier to deliver probe molecules into the reservoir. When applied in the aqueous environment, nanoparticles tend to interact with the rock surface, which may affect the mobility and stability of the nanoparticles. Deposition of nanoparticles will remove the nanoparticles from the aqueous environment, and therefore understanding the fate and transport of nanoparticles is vitally important for determination of further application strategy. The stability and transport behavior were tested under high temperature, high salinity conditions through a variety of rock formations. A non-radioactive probe molecule, which can be easily detected by mass spectrometry, triphenolamine (TPA), was attached to the nanoparticles surface. When the nanoparticles passed through columns packing with different oil saturation ground rocks, the probe molecules, THA, was selectively released from nanoparticles. This study simulates detection and quantitative analysis of the hydrocarbon content in downhole rock formations, which is vitally needed for oilfield. This technology also shows the potential to be used for DNAPL detection in ground water remediation field. Crude oil is classified as “sour” when it contains total sulfur content greater than 0.5%. Among these sulfur species, H2S is the one of main impurities in sour crude. The sour crude is toxic and corrosive to the materials of construction in pipelines and other holding and transportation vessels. Since the sulfur amount in a sample of crude depends on where it was found, if the concentration of the sulfur species in the subsurface could be accurately monitored, then geologists might be able to evaluate the quality of the crude before large scale extraction ensues. A H2S-sensitive molecule was selected to be attached to nanoparticles surface and the detection ability of H2S concentration was tested. The experimental results show that the fluorescent enhancement of the H2S-sensitive addends correlates to the H2S content.
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    Functional Data Analysis on Spectroscopic Data
    (2016-01-28) Wang, Lu; Cox, Dennis D.; Scott, David W; Zhang, Yin
    Cervical cancer is a very common type of cancer that is highly curable if treated early. We are investigating spectroscopic devices that make in-vivo cervical tissue measurements to detect pre-cancerous and cancerous lesions. This dissertation is focused on new methods and algorithms to improve the performance of the device, treating the spectroscopic measurements as functional data. The first project is to calibrate the device measurements using correction factors from a log additive model, based on results from a carefully designed experiment. The second project is a peak finding algorithm using local polynomial regression to get accurate peak location and height estimates of one of the standards (Rhodamine B) measurements from the experiment. We propose a plug-in bandwidth selection method to estimate curve peak location and height. Simulation results and asymptotic properties are presented. The third project is based on patient measurements, particularly when the diseased and non-diseased cases are highly unbalanced. A marginalized corruption methodology is introduced to improve the classification results. Performance of several classification methods is compared.
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    Nanocomposite oil sensors for downhole hydrocarbon detection
    (2016-06-28) Tour, James M.; Hwang, Chih-chau; Lu, Wei; Ruan, Gedeng; Tomson, Mason B.; Kan, Amy; Wang, Lu; Wong, Michael S.; Kini, Gautam; Hirasaki, George J.; Miller, Clarence; Rice University; United States Patent and Trademark Office
    Various embodiments of the present disclosure pertain to nanocomposites for detecting hydrocarbons in a geological structure. In some embodiments, the nanocomposites include: a core particle; a polymer associated with the core particle; a sulfur-based moiety associated with the polymer; and a releasable probe molecule associated with the core particle, where the releasable probe molecule is releasable from the core particle upon exposure to hydrocarbons. Additional embodiments of the present disclosure pertain to methods of detecting hydrocarbons in a geological structure by utilizing the nanocomposites of the present disclosure.
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    Transport of carbon nanomaterials in natural rocks and their application in oilfield exploration
    (2012) Wang, Lu; Tomson, Mason B.
    This report studies the application of carbon nanomaterials as a novel type of tracer in detection of residual oil. The carbon nanomaterials studied include oxidized carbon black (OCB) coated with different molecular weight polyvinyl alcohols(PVAs). Transport studies are conducted using columns packed with ground core materials, with synthetic seawater as the carrying fluid. Compared to lower molecular weight PVA-functionalized OCBs, the breakthrough of PVA(50K)-OCBs is less sensitive to aging and temperature; therefore, PVA(50K)-OCBs are chosen as nanoreporters to sequester chemical tags. Two different tags, 14 C labeled 2,2',5,5'-tetrachlorobiphenyl(PCB) and triphenylamine, are tested in the experiments. Efficient transport of tags through oil-field rocks and selective release when rocks contain oil are demonstrated. The kinetics of PCB adsorption is studied to better understand correlation between PCB release and oil content. A linear relationship between residual oil content and PCB release is found in flow-through experiments.