Relevant bibliographies by topics / POCS

Academic literature on the topic 'POCS'

Author: Grafiati
Published: 4 June 2021
Last updated: 19 February 2022

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Journal articles on the topic "POCS"

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Ehlers, A., J. Osborne, S. Slack, R. L. Roper, and C. Upton. "Poxvirus Orthologous Clusters (POCs)." Bioinformatics 18, no. 11 (November 1, 2002): 1544–45. http://dx.doi.org/10.1093/bioinformatics/18.11.1544.

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Li, Xiao Qin, and Kang Ling Fang. "Super-Resolution by POCS-SIFT Approach." Applied Mechanics and Materials 519-520 (February 2014): 562–67. http://dx.doi.org/10.4028/www.scientific.net/amm.519-520.562.

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Projection Onto Convex Sets theory (POCS) and Scale Invariant Feature Transform (SIFT) algorithm were introduced for super-resolution restoration of moving blurred image. In order to achieve a better restored image, a POCS-SIFT based super-resolution image restoration algorithm was proposed, which incorporates POCS theory and SIFT algorithm. From experimental results, the improved restored images are obtained by POCS-SIFT hybrid algorithm.
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Onoyama, Takumi, Wataru Hamamoto, Yuri Sakamoto, Shiho Kawahara, Taro Yamashita, Hiroki Koda, Soichiro Kawata, Yohei Takeda, Kazuya Matsumoto, and Hajime Isomoto. "Peroral Cholangioscopy-Guided Forceps Mapping Biopsy for Evaluation of the Lateral Extension of Biliary Tract Cancer." Journal of Clinical Medicine 10, no. 4 (February 5, 2021): 597. http://dx.doi.org/10.3390/jcm10040597.

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Background: Peroral cholangioscopy (POCS)-guided forceps mapping biopsy (FMB) is a method for the accurate preoperative identification of the extent of the disease of biliary tract cancer (BTC). However, the diagnostic value of POCS-FMB is still uncertain. Objectives: We evaluated the diagnostic utility of POCS-FMB for the identification of lateral extension—superficial intraductal spread longitudinally and continuously from the main lesion—of BTC. Methods: In the retrospective study, patients who received POCS-FMB and surgery for curative resection of BTC between September 2016 and August 2019 at our medical institution were enrolled. The diagnostic accuracy of POCS-FMB for the identification of lateral extension of BTC was evaluated. Furthermore, we also evaluated the factors affecting the diagnostic accuracy of POCS-FMB. Results: A total of 23 patients with BTC were enrolled, and 24 procedures of POCS-FMB from 96 sites of biliary tracts were performed. The sensitivity, specificity, and accuracy of POCS-FMB were 53.8%, 63.9%, and 63.1%, respectively. In the multivariate logistic regression analyses, the biopsy from the bifurcation of biliary tracts was a significant factor affecting the diagnostic accuracy of POCS-FMB (odds ratio 3.538, 95%; confidence interval 1.151–10.875, p = 0.027). Conclusions: The diagnostic accuracy of POCS-FMB for the identification of lateral extension of BTC was insufficient. The biopsy from the bifurcation of biliary tracts was a positive factor affecting the diagnostic accuracy of POCS-FMB.
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Kandasamy, Senthil Kumar, Balambigai Subramanian, Hemalatha Krishnamoorthy, Chandrasekaran Arumugam, Suganthi V, Yuvasri M, and Shreelogesh D. "Chemically Treated Activated Carbon for Supercapacitor Electrode Derived from Starch of Solanum Tuberosum." Journal of New Materials for Electrochemical Systems 24, no. 2 (June 30, 2021): 78–83. http://dx.doi.org/10.14447/jnmes.v24i2.a04.

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Because of the increasing demands in energy, growth in alternate energy sources is inevitable. By activation followed by carbonization of starch of solanum tuberosum makes a porous carbon network as electrode material for supercapacitor. To achieve an improvement in specific capacitance, activating the starch of solanum tuberosum using chemicals such as hydrochloric acid, phosphoric acid and sulphuric acid were done. The structural and electrochemical performance of activated carbon derived from the starch of solanum tuberosum is evaluated using FTIR, XRD, CV, GCD and EIS. The improved performance of chemically treated starch of solanum tuberosum in energy storage mechanism is ascribed to fast ionic diffusion of the electrolyte into and out of the pores. From the CV analysis, the higher specific capacitance (94 F.g-1) is obtained for sulphuric acid treated activated carbon derived from the starch of solanum tuberosum with good capacity retention ratio. From GCD analysis, 78.3, 56.7, 82.7 and 74.9 Fg-1 of specific capacitance is obtained for POC, POCH, POCP and POCS, respectively. When compared to all the prepared samples, POC exhibited small equivalent series resistance and POCS exhibited small charge transfer resistance.
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Kato, Masayuki, Takumi Onoyama, Yohei Takeda, Soichiro Kawata, Hiroki Kurumi, Hiroki Koda, Taro Yamashita, et al. "Peroral Cholangioscopy-Guided Forceps Biopsy and Endoscopic Scraper for the Diagnosis of Indeterminate Extrahepatic Biliary Stricture." Journal of Clinical Medicine 8, no. 6 (June 19, 2019): 873. http://dx.doi.org/10.3390/jcm8060873.

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Background: Peroral cholangioscopy (POCS) has become a widely-used technique in diagnosing indeterminate biliary strictures, enabling optical viewing of the biliary system and targeted biopsies under direct vision. The diagnostic utility of the new endoscopic scraper, Trefle®, for extrahepatic cholangiocarcinoma (ECC) has also been reported. However, the diagnostic utility of POCS-guided and Trefle®-assisted tissue acquisition for ECC has never been compared empirically. We evaluated the efficacy and safety of Trefle®-assisted tissue acquisition for diagnosing ECC compared with POCS-guided tissue sampling. Methods: Patients who underwent Trefle®-assisted tissue acquisition or POCS-guided forceps biopsy to differentiate ECC from benign biliary disease between April 2014 and March 2018 were enrolled retrospectively. We evaluated the diagnostic performance of Trefle®-assisted tissue acquisition and POCS-guided forceps biopsy based on pathological evaluation. We also compared adverse events associated with Trefle®-assisted tissue acquisition with those of POCS-guided forceps biopsy. Results: We enrolled 34 patients with biliary disease and performed Trefle®-assisted tissue acquisition and POCS-guided forceps biopsy in 14 and 20 patients, respectively. Sensitivity, specificity, and accuracy of Trefle®-assisted tissue acquisition were 87.5%, 83.3%, and 85.7%, respectively, and for POCS-guided forceps biopsy, these were 90.0% each. Statistical values of Trefle®-assisted tissue acquisition and POCS-guided tissue acquisition were not significantly different. There were no significant differences in the occurrence of adverse events between the Trefle®-assisted tissue acquisition and the POCS-guided forceps biopsy (35.7% vs. 25.0%, p = 0.770). Compared with patients who underwent POCS procedure, endoscopic sphincterotomy was performed for fewer patients who underwent Trefle®-assisted tissue acquisition (p < 0.001). Conclusions: The diagnostic ability of Trefle®-assisted tissue acquisition for ECC is similar to that of POCS-guided tissue acquisition. Trefle®-assisted tissue acquisition might also help to preserve the sphincter of Oddi and its digestive function.
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Kanno, Yoshihide, Shinsuke Koshita, Takahisa Ogawa, Kaori Masu, Hiroaki Kusunose, Toshitaka Sakai, Toji Murabayashi, et al. "Peroral cholangioscopy by SpyGlass DS versus CHF-B260 for evaluation of the lateral spread of extrahepatic cholangiocarcinoma." Endoscopy International Open 06, no. 11 (November 2018): E1349—E1354. http://dx.doi.org/10.1055/a-0743-5283.

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Abstract Background and study aims A newly developed peroral cholangioscopy (POCS) system, SpyGlassDS has high maneuverability. This study aimed to evaluate acceptability of the accuracy of SpyGlassDS accompanied by simultaneous POCS-guided biopsy compared with that of a traditional POCS scope, CHF-B260, to diagnose the lateral extent of extrahepatic cholangiocarcinoma (LEC). Patients and methods Patients who underwent surgical resection after preoperative examinations to diagnose LEC were evaluated. POCS by CHF-B260 was performed if there was discrepancy between preceding fluoroscopy-guided biopsy findings and other examinations between January 2004 and September 2015 (group A, n = 56); and POCS plus POCS-guided mapping biopsy by SpyGlassDS was performed in all surgical candidates between October 2015 and December 2017 (group B, n = 20). The main outcome measure was the accuracy of overall preoperative diagnosis (OPD) of LEC defined based on all examinations, including POCS. Results Accuracy of OPD for the liver side and the ampullary side was 93 % and 100 %, respectively, in group A, and 84 % and 100 %, respectively, in group B (P = 0.37 for the liver side; P, not available for the ampullary side). Diagnostic accuracy of simple optical evaluation by POCS for the liver side and the ampullary side was 83 % and 100 %, respectively, in group A, and 58 % and 88 %, respectively, in group B (P = 0.29 for the liver side; P = 0.40 for the ampullary side). Conclusions POCS by SpyGlassDS was found to be acceptable and could be a standard approach for diagnosis of LEC.
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Tanisaka, Yuki, Shomei Ryozawa, Kouichi Nonaka, Masami Yasuda, Akashi Fujita, Tomoya Ogawa, Masafumi Mizuide, Tomoaki Tashima, and Ryuichiro Araki. "Diagnosis of Biliary Strictures Using Probe-Based Confocal Laser Endomicroscopy under the Direct View of Peroral Cholangioscopy: Results of a Prospective Study (with Video)." Gastroenterology Research and Practice 2020 (December 31, 2020): 1–9. http://dx.doi.org/10.1155/2020/6342439.

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Background. The accurate diagnosis of biliary strictures remains problematic. The aim of the present study was to prospectively evaluate the clinical utility of probe-based confocal laser endomicroscopy (pCLE) under the direct view of peroral cholangioscopy (POCS) for the diagnosis of biliary strictures. Methods. Consecutive patients with biliary strictures were included. We investigated sensitivity, specificity, and accuracy to diagnose malignancy for (1) ERCP alone, (2) POCS, (3) pCLE under the direct view of POCS, and (4) tissue sampling under the direct view of POCS. Results. A total of 30 patients (17 with malignant lesions) were prospectively enrolled. (1) ERCP alone showed 88.2% sensitivity, 46.2% specificity, and 70% (95% confidence interval (CI), 52.1%–83.3%) accuracy. (2) POCS showed 100% sensitivity, 76.9% specificity, and 90% (95% CI, 74.4%–96.5%) accuracy. (3) pCLE under the direct view of POCS showed 94.1% sensitivity, 92.3% specificity, and 93.3% (95% CI, 78.7%–98.8%) accuracy. (4) Tissue sampling under the direct view of POCS showed 82.4% sensitivity, 100% specificity, and 90% (95% CI, 74.4%–96.5%) accuracy. Conclusions. pCLE under the direct view of POCS provided highly accurate and sensitive characterization of biliary strictures and showed the potential for more diagnostic reliability and reduction of delays in diagnosis. This trial was registered at UMIN (registration number: UMIN000033801).
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van Wyk, B. J., and M. A. van Wyk. "A POCS-based graph matching algorithm." IEEE Transactions on Pattern Analysis and Machine Intelligence 26, no. 11 (November 2004): 1526–30. http://dx.doi.org/10.1109/tpami.2004.95.

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Stasiński, Ryszard, and Janusz Konrad. "Improved POCS reconstruction of stereoscopic views." Signal Processing: Image Communication 17, no. 9 (October 2002): 689–704. http://dx.doi.org/10.1016/s0923-5965(02)00080-2.

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Wang, Benfeng, Ru-Shan Wu, Yu Geng, and Xiaohong Chen. "Dreamlet-based interpolation using POCS method." Journal of Applied Geophysics 109 (October 2014): 256–65. http://dx.doi.org/10.1016/j.jappgeo.2014.08.008.

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Dissertations / Theses on the topic "POCS"

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Stelzer, Murilo. "Restauração de imagens de microscopia confocal utilizando técnicas POCS." Universidade Federal de São Carlos, 2005. https://repositorio.ufscar.br/handle/ufscar/617.

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Computer Optical Sectioning Microscopy (COSM) is widely used in morphological studies of cellular structures. COSM appears as a great challenge to digital image processing, because the large size of the three-dimensional files. The major problem in COSM is the blurring, which practically turn the image unusable without the use of digital image processing techniques. In this work, based on projection onto convex set were developed image processing techniques to restore COSM images, obtained by a confocal microscope. Although confocal microscope presents less blurring than the wide field microscope, it has a larger Poisson noise level. To reduce the Poisson noise the Anscombe Transform (AT) was used as well a pointwise Wiener Filter. The POCS methods were evaluated by means of simulations, using synthetic images (phantom), and the results was evaluated by ISNR (Improvement in Signal Noise Ratio) and UIQ (Universal Quality Index). The developed algorithms, using RAP (Row Action Projection) present satisfactory results, but the computational costs were expensive.
A técnica de Microscopia de Seccionamento Óptico por Computador (COSM) é muito utilizada no estudo morfológico de estruturas celulares. Essa técnica apresenta um grande desafio para a área de processamento de imagens, pois os arquivos tridimensionais possuem grande volume de dados para serem processados. O principal problema do COSM é o borramento existente, que praticamente inviabiliza a utilização dessa imagem sem o uso de técnicas de processamento de imagem. Nesse trabalho, foram desenvolvidas técnicas de projeção em conjuntos convexos POCS (Projection Onto Convex Sets) de processamento de imagens para a restauração das imagens de COSM, obtidas por microscópio confocal. Embora os microscópios confocais apresentem menor borramento da imagem que os microscópios wide field, ele possuem um nível maior de ruído Poisson. Para atenuar o ruído Poisson foi utilizada a Transformada de Anscombe (AT) e o filtro de Wiener pontual. Os métodos POCS, foram avaliados através de simulações utilizando imagens sintéticas (phantoms), e os resultados foram avaliados através do ISNR(Improvement Signal to Noise Ratio) e do UIQ(Universal Quality Index). Os algoritmos desenvolvidos, utilizando RAP (Row Action Projection) apresentaram bons resultados, mas o custo computacional para imagem tridimensional é bastante elevado.
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Papa, João Paulo. "Restauração das imagens do satélite CBERS-1 utilizando POCS." Universidade Federal de São Carlos, 2005. https://repositorio.ufscar.br/handle/ufscar/608.

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Financiadora de Estudos e Projetos
The number of applications in remote sensing has widely increased in the last years. The reason for this is mainly the high quality of imaging systems onboard. Among this new generation of satellites, the CBERS-1 (China-Brazil Earth Resources Satellite) was developed through a partnership between Brazil and China, and its main mission is to capture high-resolution images of the Earth using panchromatic and multispectral detectors. However, the information provided by remote sensing needs to be processed to better reflect the radiometric quality of the data, using for this purpose a technique called image restoration. The main goal of image restoration is the reconstruction or recovery of the degraded image using some a priori knowledge of the degradation phenomenon. In this work we developed five image restoration algorithms based on the theory of convex projections, which were obtained through the CBERS-1 band 2 CCD sensor. These algorithms are based on the application of restrictions in convex sets form, through the POCS (Projections Onto Convex Sets) method, where the intersection among these sets, if it exists, gives a satisfactory solution for the problem. The simulations were developed using the RAP (Row-Action Projections), the SIRT (Simultaneous Iterative Reconstruction Technique) and an algorithm that uses prototype image constraints, which were obtained by the methods cited above and by the MIF (Modified Inverse Filter). The results were visually and numerically evaluated.
A quantidade de aplicações oriundas do sensoriamento remoto tem aumentado significativamente nos últimos anos. Isso se deve, principalmente, à alta qualidade dos equipamentos a bordo dos sistemas sensores. Entre essa nova geração de satélites, o CBERS-1 (China-Brazil Earth Resources Satellite) foi desenvolvido através de uma parceria entre Brasil e China, sendo sua missão principal a de capturar imagens de alta resolução da Terra utilizando detectores pancromáticos e multiespectrais. Contudo, as informações oriundas do sensoriamento remoto necessitam ser processadas para melhorar a qualidade radiométrica dos dados, utilizando para tal uma técnica conhecida por restauração de imagens, sendo seu principal objetivo a reconstrução ou recuperação de uma imagem degradada utilizando algum conhecimento a priori do fenômeno de degradação. No presente trabalho foram desenvolvidos cinco algoritmos de restauração de imagens baseados na teoria de projeções convexas, as quais foram obtidas através do sensor CCD da banda 2 do satélite CBERS-1. Estes algoritmos são baseados na aplicação de restrições na forma de conjuntos convexos, através do método de POCS (Projections Onto Convex Sets), sendo que a intersecção entre esses conjuntos, caso exista, fornece uma solução satisfatória para o problema. As simulações foram desenvolvidas utilizando o RAP (Row-Action Projections), SIRT (Simultaneous Iterative Reconstruction Technique) e um algoritmo que utiliza uma restrição de imagem protótipo, a qual foi obtida pelos métodos citados acima e pelo FIM (Filtro Inverso Modificado). Os resultados foram avaliados visualmente e através de análises numéricas.
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Salina, Fernando Vernal. "Reconstrução tomográfica de imagens utilizando técnicas POCS seqüenciais e paralelas." Universidade Federal de São Carlos, 2001. https://repositorio.ufscar.br/handle/ufscar/392.

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Financiadora de Estudos e Projetos
In this dissertation four algorithms are presented for the tomographic reconstruction of images using methods denominated POCS - Projections onto Convex Sets, which are the ART - Algebraic Reconstruction Technique, the SIRT - Simultaneous Iterative Reconstructive Technique, the sequencial POCS and parallel POCS. A comparison is made between the reconstruction methods named above, in the presence of noise and in the reconstruction from limited view. In each reconstruction, the result of each iteration is compared with the desired image, also showing the convergence curve for each method. For the tomographic reconstructions, projections from test bodies obtained throught simulation were used and also experimental projections obtained by the mini-tomograph scanner of CNPDIA-EMBRAPA. Although were considered only the reconstruction based an projections obtained with parallel beams, the methods here described can also reconstruct images that are independent of the source-detector geometry used by the tomograph scanner. The use of restrictions over the solutions, as in the case of serial and parallel POCS, demonstrated efficiency in reducing the variability due to the ill-conditioning of the problem.
Nesta dissertação são apresentados quatro algoritmos para reconstrução tomográfica de imagens utilizando o método de projeções em conjuntos convexos (POCS - Projections onto Convex Sets), sendo eles o ART (Algebraic Reconstruction Technique), o SIRT (Simultaneous Iterative Reconstructive Technique), o POCS sequencial e o POCS paralelo. É feita a comparação entre os métodos de reconstrução, acima citados, na presença de ruído e na reconstrução à partir de ângulos limitados. Em cada reconstrução o resultado obtido em cada iteração é comparado com a imagem desejada, mostrando-se também o gráfico de convergência de cada método. Utilizaram-se, para reconstrução tomográfica, projeções de corpos de testes obtidas através de simulação e também projeções obtidas experimentalmente no minitomógrafo do CNPDIA-EMBRAPA. Embora seja considerada somente a reconstrução a partir de projeções obtidas em tomógrafos com feixe de raios paralelos, os métodos expostos podem reconstruir imagens independentemente da geometria fonte-detetor utilizada pelo tomógrafo. O uso de restrições sobre as soluções, como no caso dos métodos POCS sequencial e paralelo, mostrou-se eficaz para reduzir as variações devido ao malcondicionamento do problema.
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Weerasinghe, Arachchige Chaminda Perera. "Rotational Motion Artifact Correction in Magnetic Resonance Imaging." University of Sydney. Electrical and Information Engineering, 1999. http://hdl.handle.net/2123/357.

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The body motion of patients, during magnetic resonance (MR) imaging causes significant artifacts in the reconstructed image. Artifacts are manifested as a motion induced blur and ghost repetitions of the moving structures. which obscure vital anatomical and pathological detail. The techniques that have been proposed for suppressing motion artifacts fall into two major categories. Real-time techniques attempt to prevent the motion from corrupting the data by restricting the data acquisition times or motion of the patients, whereas the post-processing techniques use the information embedded in the corrupted data to restore the image. Most methods currently in widespread use belong to the real-time techniques, however with the advent of fast computing platforms and sophisticated signal processing algorithms, the emergence of post-processing techniques is clearly evident. The post-processing techniques usually demand an appropriate model of the motion. The restoration of the image requires that the motion parameters be determined in order to invert the data degradation process. Methods for the correction of translational motion have been studied extensively in the past. The subject of this thesis encompasses the rotational motion model and the effect of rotational motion on the collected MR data in the spatial frequency space (k-space), which is in general, more complicated than the translational model. Rotational motion artifacts are notably prevalent in MR images of head, brain and limbs. Post-processing techniques for the correction of rotational motion artifacts often involve interpolation and re-gridding of the acquired data in the k-space. These methods create significant data overlap and void regions. Therefore, in the past, proposed corrective techniques have been limited to suppression of artifacts caused by small angle rotations. This thesis presents a method of managing overlap regions, using weighted averaging of redundant data, in order to correct for large angle rotations. An iterative estimation technique for filling the data void regions has also been developed by the use of iterated application of projection operators onto constraint sets. These constraint sets are derived from the k-space data generated by the MR imager, and available a priori knowledge. It is shown that the iterative algorithm diverges at times from the required image, due to inconsistency among the constraint sets. It is also shown that this can be overcome by using soft. constraint sets and fuzzy projections. One of the constraints applied in the iterative algorithm is the finite support of the imaged object, marked by the outer boundary of the region of interest (ROI). However, object boundary extraction directly from the motion affected MR image can be difficult, specially if the motion function of the object is unknown. This thesis presents a new ROI extraction scheme based on entropy minimization in the image background. The object rotation function is usually unknown or unable to be measured with sufficient accuracy. The motion estimation algorithm proposed in this thesis is based on maximizing the similarity among the k-space data subjected to angular overlap. This method is different to the typically applied parameter estimation technique based on minimization of pixel energy outside the ROI, and has higher efficiency and ability to estimate rotational motion parameters in the midst of concurrent translational motion. The algorithms for ROI extraction, rotation estimation and data correction have been tested with both phantom images and spin echo MR images producing encouraging results.
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Salina, Fernando Vernal. "Métodos híbridos para reconstrução tomográfica de imagens usando POCS e teoria da estimação." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-06042011-091943/.

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Nesta tese é apresentado um novo método de reconstrução de imagens, por tomografia de transmissão, de projeções sujeitas a ruído na contagem de fótons. O método de reconstrução selecionado utiliza a técnica POCS (Projections Onto Convex Sets). A estimação das projeções originais a partir das observações ruidosas se dá por meio de quatro métodos: a) estimação utilizando o critério MAP (Maximum a Posteriori); b) filtragem nos coeficientes wavelets das projeções ruidosas; c) aplicação do filtro de Wiener pontual e d) aplicação do filtro de Goodman-Belsher. É apresentado o resultado da reconstrução após a estimação das projeções, mostrando o ISNR (Improvement Signal-to-Noise Ratio) entre as imagens reconstruídas, a partir das projeções ruidosas, com a técnica POCS, estimando as projeções e sem a realização da estimação. Foram utilizados, para reconstrução tomográfica, projeções de corpos de prova obtidos por meio de simulação e também projeções obtidas experimentalmente no minitomógrafo do CNPDIA - EMBRAPA. O uso de estimação sobre as projeções ruidosas mostrou-se eficaz para melhorar a relação sinal-ruído na imagem final, pois esse pré-processamento faz com que os conjuntos impostos pelas projeções sejam mais restritivos. Deve-se observar que a melhoria das imagens obtidas com o uso de filtragem das projeções é obtida com uma relação custo-benefício bastante baixa, pois a maior parte do custo computacional está na fase de reconstrução das imagens.
In this thesis is pesented a new method for image reconstruction, by transmission tomography, for projections under noise in the counting of photons. The selected method of reconstruction uses the POCS (Projections Onto Convex Sets) technique. The estimation of the original projections from the noisy projections observed is performed through four methods: a) estimation using the MAP (Maximum a Posteriori) criteria; b) through of filtering of the wavelets coefficients of the noisy projections; c) using the pointwise Wiener filter and d) using the Goodman-Belsher filter. We present the result of reconstruction after projection estimation, showing the ISNR (Improvement Signal-to-Noise Ratio) between the reconstructed images on noisy projections, using POCS technique after the estimated projections and without this estimation. We use, for tomographic reconstruction, test body projections obtained through simulation and also projections obtained experimentally in the minitomograph scanner of CNPDIA-EMBRAPA. The use of estimation on noisy projections demonstrated to be efficient in improving the signalnoise ratio in the final image, since this pre-processing makes the sets that projections more restrictive. We should observe that the use of projection filtering is obtained with a cost-benefit ratio rather low, since the largest part of the computational effort is in the image reconstruction phase.
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Pérez, Reátegui Daniel Ernesto. "Programación del algoritmo POCS para mejorar la resolución de imágenes de campos de cultivo." Bachelor's thesis, Pontificia Universidad Católica del Perú, 2015. http://tesis.pucp.edu.pe/repositorio/handle/123456789/6449.

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El presente trabajo de tesis surgió debido a la necesidad de obtener imágenes de campos de cultivo de alta resolución a partir de un conjunto de imágenes de baja resolución capturadas por un dispositivo óptico. La propiedad de desplazamiento sub-pixel existente entre las imágenes de baja resolución capturadas por el dispositivo óptico hace posible la obtención de imágenes digitales de alta resolución mediante la aplicación de un algoritmo de reconstrucción de imágenes. Con el fin de poder incrementar la resolución de las imágenes de campos de cultivo, de tal modo que estas puedan ser procesadas y analizadas con mayor precisión, se seleccionó y programó el algoritmo POCS (Projections Onto Convex Sets) debido a su robustez, simplicidad y flexibilidad para incorporar información conocida a priori de las imágenes deseadas al proceso de reconstrucción. El presente trabajo se desarrolla en cuatro capítulos. En el primer capítulo se presenta el concepto de Agricultura de Precisión y la necesidad de aplicar técnicas que mejoren la resolución de imágenes de campos de cultivo. En el segundo capítulo se describen los principales problemas que presentan los dispositivos ópticos para aumentar la resolución de imágenes, se presenta el modelo que describe el proceso de degradación de imágenes y se realiza un recuento de los principales algoritmos que aumentan la resolución de las mismas. En el tercer capítulo se presentan los objetivos del presente trabajo de tesis, se detalla el marco teórico del algoritmo POCS y se muestra la programación del mismo. En el cuarto capítulo se definen las métricas usadas para evaluar el algoritmo y se presentan los resultados de diversas pruebas aplicadas a las imágenes de campos de cultivo. Finalmente, se concluyó que el algoritmo POCS incrementa la resolución de imágenes de campos de cultivo de manera satisfactoria, además, se concluyó que POCS presentó mejor desempeño con respecto a los algoritmos de interpolación y de deconvolución que formaron parte de las pruebas.
Tesis
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Chongburee, Wachira. "Implementation of Iterative Reconstruction of Images from Multiple Bases Representations." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/35379.

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Usually, image compression techniques that use only one transform exhibit some poor properties. For instance, the Discrete Cosine Transform (DCT) cannot efficiently represent high frequency components, resulting in blurred images. The Multiple Bases Representation (MBR) compression technique, which uses two or more transforms, is found to be superior to the single transform techniques in terms of representation efficiency. However, some bits in the MBR representation are needed to track the basis information. The MBR image quality is deteriorated by discontinuities at block boundaries, as is the standard DCT transform.

In this thesis, test images are distorted by MBR compression using a Recursive Residual Projection algorithm. This algorithm is a sub-optimal method to find the best basis vector subset for representing images based on multiple orthogonal bases. The MBR distorted images are reconstructed by the iterative method of Projection onto Convex Sets (POCS). Many constraints that form convex sets are reviewed and examined.

Due to the high distortion at the block boundaries, some constraints are introduced particularly to reduce artifacts at the boundaries. Some constraints add energy to the reconstructed images while others remove energy. Thus, the initial vectors play a key role in the performance of the POCS method for better MBR reconstruction. This thesis also determines the most appropriate initial vector for each constraint.

Finally, the composite projections associated with the sign, minimum decreasing and norm-of-slope constraints are used to improve the reconstruction of the MBR distorted images and the effect of ordering of the projections is investigated.
Master of Science

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Fumat, Guillaume. "Etude et génération de formes d'ondes "ad hoc" pour les communications. : Une approche algébrique pour l'étude de l'efficacité spectrale et la réduction du PAPR dans les TDCS." Thesis, Toulouse, INSA, 2011. http://www.theses.fr/2011ISAT0030/document.

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Avec le besoin croissant en bande-passante, les technologies dites de radio-cognitive sont de plus en plus étudiées par la communauté scientifique. L’enjeu est d’utiliser au mieux le spectre disponible. L'une de ces technologies, Transform Domain Communication System (TDCS), dont les performances en termes d’efficacité énergétique et spectrale étaient jusqu'à présent méconnues, constitue le sujet d'étude de cette thèse. Après une présentation du contexte scientifique et industriel de la thèse, le système TDCS est introduit, ainsi que ses similarités et différences avec OFDM et MC-CDMA. Le système est ensuite décrit sous le formalisme algébrique des modulations linaires. Cela a permis d’établir une expression de l’efficacité spectrale du système. Plusieurs techniques sont alors proposées pour améliorer celle-ci tout en améliorant, dans certains cas, le taux d’erreur binaire. Étant composé d’un de plusieurs composantes sinusoïdales, le signal TDCS souffre d’un fort Peak-to-Average Power Ratio (PAPR). La théorie ensembliste est alors présentée puis mise à profit en troisième partie de cette thèse pour proposer les algorithmes Douglas-Rachford et ROCS de réduction du PAPR des signaux TDCS. Ces algorithmes convergent plus rapidement et vers des valeurs plus basses que l’algorithme POCS précédemment utilisé dans la littérature
For about ten years, spectrum scarcity and the growing need of bandwidth have pushed the studies on cognitive-radio technologies to counter this waste. Among them: the Transform Domain Communication System (TDCS), on which this thesis focuses. Until now, TDCS’ performance in terms of spectral and power efficiency was largely unknown. After introducing the thesis’ industrial and scientific context, the TDCS is introduced and compared with popular technologies such as OFDM and MC-CDMA. The system is then studied by means of the linear modulations’ algebraic framework. This has led to the TDCS’ spectral efficiency determination and to new design rules to jointly achieve a better spectral efficiency and a lower BER. Several methods are then proposed to further increase the spectral efficiency by means of a dense multidimensional modulation. Since a TDCS signal is made of several sines, it suffers from a strong Peak-to-Average Power Ratio (PAPR). Set theoretic estimation is then introduced in a third part and new PAPR-reduction algorithms such as Douglas-Rachford and Reflection Onto Convex Sets are brought to light and achieve better performance than the usual POCS algorithm regarding to the convergence rate, as well as the achieved PAPR
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Baldwin, Maria T. "AMNESTY INTERNATIONAL, HUMAN RIGHTS & U.S POLICY." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1162681572.

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Bengtsson, Martin, and Emil Ågren. "Image enhancement of license plates in images using Super Resolution." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-121682.

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Bildgruppen på enheten för dokument och informationsteknik hos SKL har ett behov av att kunna förbättra bilder med extremt låg upplösning. Detta bildmaterial kan komma från diverse övervakningskameror där det intressanta objektet endast utgör en väldigt liten del, i detta fall registreringsskyltar på förbipasserande bilar. Att skapa en högupplöst bild av en registreringsskylt utav ett fåtal lågupplösta bilder är ett välkänt problem med ett flertal förslag på metoder och lösningar. I denna rapport kommer vi att undersöka vilka metoder som passar bäst vid bildförbättring av registreringsskyltar. Vi kommer även att skapa ett användargränssnitt där man kan läsa in en bild och välja mellan att automatiskt hitta registreringsskylten i bilden eller att manuellt klippa ut den. Efter att man erhållit en bild innehållandes endast registreringsskylten ska de olika implementerade bildförbättringsmetoderna kunna användas. Slutligen diskuteras vilka för- och nackdelar de respektive metoderna har. Förslag på eventuella förbättringar och hur man kan utveckla dessa metoder vidare presenteras därtill.
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Books on the topic "POCS"

1

Sisterna, Jaume. La senyora: Pocs jocs fan carta. [Gaüses, Girona]: Llibres del Segle, 2000.

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Sisterna, Jaume. La senyora: Pocs jocs fan carta. [Gaüses, Girona]: Llibres del Segle, 2000.

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Poes poes poes. Amsterdam: Nijgh & Van Ditmar, 2001.

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Ubillos, Germán. Poco a poco. Fuenlabrada (Madrid): Entrelíneas Editores, 2014.

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Poco a poco. 3rd ed. Boston, Mass., U.S.A: Heinle & Heinle Publishers, 1994.

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Hendrickson, James M. Poco a poco. 4th ed. Boston: Heinle & Heinle Publishers, 1997.

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Cállate poco a poco. Caracas: Monte Ávila Editores Latinoamericana, 2007.

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Pous, Jean. Jean Pous.: François Pous. Roche-la-Molière: Ceysson, 2008.

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Pops. New York, N.Y. (440 Park Ave., S., New York 10016): Dramatists Play Service, 1987.

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Pops. Sankt-Peterburg: Amfora, 2007.

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Book chapters on the topic "POCS"

1

Choi, Kang-Sun, Jun-Ki Cho, Min-Cheol Hwang, and Sung-Jea Ko. "POCS-Based Enhancement of De-interlaced Video." In Computer and Information Sciences - ISCIS 2003, 667–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-39737-3_83.

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Li, Juan, Jin Wu, Guang Hu, and Shen Yang. "Super-Resolution Image Reconstruction Based on Improved POCS Algorithm." In Lecture Notes in Electrical Engineering, 743–52. London: Springer London, 2012. http://dx.doi.org/10.1007/978-1-4471-4796-1_95.

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Luo, Jun, and Ying Chen. "Improve the Resolution of Medical Image Using POCS Algorithm." In Lecture Notes in Electrical Engineering, 757–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-34531-9_80.

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Bong, Wonsun, and Yong Cheol Kim. "High Resolution Image Reconstructed by ARPS Motion Estimation and POCS." In Convergence and Hybrid Information Technology, 113–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-24106-2_15.

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Shang, Li, Shu-fen Liu, and Zhan-li Sun. "Image Super-Resolution Reconstruction Based on Sparse Representation and POCS Method." In Intelligent Computing Theories and Methodologies, 348–56. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-22180-9_34.

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Kim, Yoon, Chun-Su Park, Kyunghun Jang, and Sung-Jea Ko. "Improved POCS-Based De-blocking Algorithm for Block-Transform Compressed Images." In Computer and Information Sciences - ISCIS 2003, 627–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-39737-3_78.

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Kwon, Goo-Rak, Hyo-Kak Kim, Chun-Soo Park, Yoon Kim, and Sung-Jea Ko. "Improved POCS-Based Deblocking Technique Using Wavelet Transform in Block Coded Image." In Advances in Multimedia Information Processing - PCM 2006, 676–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11922162_78.

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Hussain, Shehzad, Zoran Kostić, and B. Gopinath. "BER Performance of Adaptive RAKE Receiver Using Tap Weights Obtained by POCS Deconvolution Technique." In Wireless Personal Communications, 119–30. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4757-2368-7_8.

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Fan, Chong, Jianya Gong, Jianjun Zhu, and Lihua Zhang. "POCS Super-Resolution Sequence Image Reconstruction Based on Image Registration Excluded Aliased Frequency Domain." In Lecture Notes in Computer Science, 1240–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/978-3-540-37275-2_155.

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Tye, Gary, and John Brown. "Pons." In Encyclopedia of Clinical Neuropsychology, 2715–16. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-57111-9_352.

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Conference papers on the topic "POCS"

1

Feichtinger, Hans G., N. Kaiblinger, and Peter Prinz. "POCS approach to Gabor analysis." In Sixth International Workshop on Digital Image Processing and Computer Graphics, edited by Emanuel Wenger and Leonid I. Dimitrov. SPIE, 1998. http://dx.doi.org/10.1117/12.301373.

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Kim, Bona, Soocheol Jeong, Joongmoo Byun, and Soon Jee Seol. "Curvelet transform-based POCS inf-kdomain." In SEG Technical Program Expanded Abstracts 2012. Society of Exploration Geophysicists, 2012. http://dx.doi.org/10.1190/segam2012-1063.1.

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Colclough, Douglas D., and Edward L. Titlebaum. "Delay-doppler pocs for specular multipath." In Proceedings of ICASSP '02. IEEE, 2002. http://dx.doi.org/10.1109/icassp.2002.5745519.

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Colclough and Titlebaum. "Delay-Doppler POCS for specular multipath." In IEEE International Conference on Acoustics Speech and Signal Processing ICASSP-02. IEEE, 2002. http://dx.doi.org/10.1109/icassp.2002.1004780.

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Stein, Jaime A., Scott Boyer, Kevin Hellman, and John Weigant. "Application of POCS interpolation to exploration." In SEG Technical Program Expanded Abstracts 2010. Society of Exploration Geophysicists, 2010. http://dx.doi.org/10.1190/1.3513590.

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Yu, G. S., M. W. Marcellin, and M. M. K. Liu. "POCS based error concealment for packet video." In Proceedings DCC '97. Data Compression Conference. IEEE, 1997. http://dx.doi.org/10.1109/dcc.1997.582151.

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Bozkurt, G., and A. Enis Cetin. "Restoration of error-diffused images using POCS." In 1999 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings. ICASSP99 (Cat. No.99CH36258). IEEE, 1999. http://dx.doi.org/10.1109/icassp.1999.757528.

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Duraisamy, Prakash, Mohammad S. Alam, and Stephen C. Jackson. "Error correction in image registration using POCS." In SPIE Defense, Security, and Sensing, edited by David P. Casasent and Tien-Hsin Chao. SPIE, 2011. http://dx.doi.org/10.1117/12.886573.

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Kuo, S., and R. J. Mammone. "Refinement of EM restored images using adaptive POCS." In [Proceedings] ICASSP 91: 1991 International Conference on Acoustics, Speech, and Signal Processing. IEEE, 1991. http://dx.doi.org/10.1109/icassp.1991.151015.

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Gevrekci, Murat, Bahadir K. Gunturk, and Yucel Altunbasak. "POCS-Based Restoration of Bayer-Sampled Image Sequences." In 2007 IEEE International Conference on Acoustics, Speech, and Signal Processing. IEEE, 2007. http://dx.doi.org/10.1109/icassp.2007.366017.

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Reports on the topic "POCS"

1

Shockey, Edward G., Alan G. Bolf, Paul F. Jones, Joseph J. Schwab, and Kevin P. Chaffee. Functionalized Polyhedral Oligosilsesquioxane (POSS) Macromers: New Graftable POSS-Hydride, POSS-Alpha-Olefin, POSS-Epoxy, and POSS-Chlorosilane Macromers and POSS-Siloxane Triblocks. Fort Belvoir, VA: Defense Technical Information Center, December 1997. http://dx.doi.org/10.21236/ada397977.

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Haddad, Timothy S., Brent D. Viers, and Shawn H. Phillips. Polyhedral Oligomeric Silsesquioxane (POSS) Styrene Macromers. Fort Belvoir, VA: Defense Technical Information Center, November 2001. http://dx.doi.org/10.21236/ada410398.

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Viers, B. D., Rene I. Gonzalez, and Shawn H. Phillips. POSS Polymers for Space: Entrepreneurial Research. Fort Belvoir, VA: Defense Technical Information Center, October 2003. http://dx.doi.org/10.21236/ada419193.

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Mercado Percia, Heiner, ed. #ImageForensics: entrevista a Elisabeth Bik. Journals & Authors - Libro abierto, September 2021. http://dx.doi.org/10.25012/blog.14.09.2021.

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Elisabeth Bik es una microbióloga nacida en Países Bajos que se ha dedicado desde hace algunos años a tratar en su blog Science Integrity Digest temas de integridad científica. Su cuenta de Twitter @MicrobiomDigest, tiene más de 100 mil seguidores y en ella ha tomado mucha fuerza su hashtag #ImageForensics. En nuestro medio, poco se habla de la manipulación de las imágenes como una mala práctica en la ciencia, pero como nos lo muestra la doctora Elisabeth Bik, es muy fácil de identificar y hasta un deber para con la ciencia estar atentos a estos fraudes. Ella ha agudizado su visión para detectar rápidamente imágenes fraudulentas sin la ayuda de ningún software especializado, salvo en algunos pocos casos en los que debe confirmar las sospechas.
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Cañete Alonso, Rosa. Democracias capturadas: el gobierno de unos pocos. Oxfam, CLASCO, November 2018. http://dx.doi.org/10.21201/2018.3521.

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Mabry, Joseph M., Timothy S. Haddad, and Steven A. Svejda. Polymer Nanocomposites Containing Polyhedral Oligomeric Silsesquioxanes (POSS). Fort Belvoir, VA: Defense Technical Information Center, December 2004. http://dx.doi.org/10.21236/ada433239.

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Fox, Douglas. POSS-Modified Cellulose for Improved Biopolymer Performance. Fort Belvoir, VA: Defense Technical Information Center, September 2011. http://dx.doi.org/10.21236/ada566210.

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Mei, Fan, and Mikhail Pekour. Portable Optical Particle Spectrometer (POPS) Instrument Handbook. Office of Scientific and Technical Information (OSTI), November 2020. http://dx.doi.org/10.2172/1725831.

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Phillips, S., R. Gonzales, K. Chaffee, T. Haddad, and G. Hoflund. Remarkable AO Resistance of POSS Inorganic/Organic Polymers. Fort Belvoir, VA: Defense Technical Information Center, January 2000. http://dx.doi.org/10.21236/ada397900.

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Moore, Brian M., Sean M. Ramire, Gregory R. Yandek, Timothy S. Haddad, and Joseph M. Mabry. Increasing the Solubility of Inert Peripherally Aromatic POSS. Fort Belvoir, VA: Defense Technical Information Center, October 2010. http://dx.doi.org/10.21236/ada533416.

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