Relevant bibliographies by topics / Comb filtering

Academic literature on the topic 'Comb filtering'

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Published: 4 June 2021
Last updated: 9 February 2022

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Journal articles on the topic "Comb filtering"

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Horn, J., M. Jansen, and S. J. Prange. "Adaptive comb-filtering using neural networks." IEEE Transactions on Consumer Electronics 43, no. 3 (1997): 833–36. http://dx.doi.org/10.1109/30.628727.

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Nehorai, A., and B. Porat. "Adaptive comb filtering for harmonic signal enhancement." IEEE Transactions on Acoustics, Speech, and Signal Processing 34, no. 5 (October 1986): 1124–38. http://dx.doi.org/10.1109/tassp.1986.1164952.

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Ferreira, José L., Yan Wu, and Ronald M. Aarts. "Enhancement of the Comb Filtering Selectivity Using Iterative Moving Average for Periodic Waveform and Harmonic Elimination." Journal of Healthcare Engineering 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/7901502.

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A recurring problem regarding the use of conventional comb filter approaches for elimination of periodic waveforms is the degree of selectivity achieved by the filtering process. Some applications, such as the gradient artefact correction in EEG recordings during coregistered EEG-fMRI, require a highly selective comb filtering that provides effective attenuation in the stopbands and gain close to unity in the pass-bands. In this paper, we present a novel comb filtering implementation whereby the iterative filtering application of FIR moving average-based approaches is exploited in order to enhance the comb filtering selectivity. Our results indicate that the proposed approach can be used to effectively approximate the FIR moving average filter characteristics to those of an ideal filter. A cascaded implementation using the proposed approach shows to further increase the attenuation in the filter stopbands. Moreover, broadening of the bandwidth of the comb filtering stopbands around −3 dB according to the fundamental frequency of the stopband can be achieved by the novel method, which constitutes an important characteristic to account for broadening of the harmonic gradient artefact spectral lines. In parallel, the proposed filtering implementation can also be used to design a novel notch filtering approach with enhanced selectivity as well.
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Hu, H. T. "Robust pitch estimation based on modified comb filtering approach." Electronics Letters 43, no. 25 (2007): 1471. http://dx.doi.org/10.1049/el:20071953.

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Wen Jin, Xin Liu, M. S. Scordilis, and Lu Han. "Speech Enhancement Using Harmonic Emphasis and Adaptive Comb Filtering." IEEE Transactions on Audio, Speech, and Language Processing 18, no. 2 (February 2010): 356–68. http://dx.doi.org/10.1109/tasl.2009.2028916.

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Ferreiro, T. I., T. P. Lamour, J. Sun, and D. T. Reid. "1.4 GHz femtosecond comb generation by Fabry‐Pérot filtering of optical parametric oscillator frequency comb." Electronics Letters 49, no. 13 (June 2013): 833–35. http://dx.doi.org/10.1049/el.2013.1504.

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Kitamura, Toshiaki. "Comb-Line Filter with Coupling Capacitor in Ground Plane." Active and Passive Electronic Components 2011 (2011): 1–6. http://dx.doi.org/10.1155/2011/919240.

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A comb-line filter with a coupling capacitor in the ground plane is proposed. The filter consists of two quarter-wavelength microstrip resonators. A coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics are investigated through numerical simulations as well as experiments. Filtering characteristics that have attenuation poles at both sides of the passband are obtained. The input susceptances of even and odd modes and coupling coefficients are discussed. The filters using stepped impedance resonators (SIRs) are also discussed, and the effects of the coupling capacitor for an SIR structure are shown.
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Nishiyama, Akiko, Satoru Yoshida, Takuya Hariki, Yoshiaki Nakajima, and Kaoru Minoshima. "Sensitivity improvement of dual-comb spectroscopy using mode-filtering technique." Optics Express 25, no. 25 (December 6, 2017): 31730. http://dx.doi.org/10.1364/oe.25.031730.

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Šmíd, R., A. Hänsel, L. Pravdová, J. Sobota, O. Číp, and N. Bhattacharya. "Comb mode filtering silver mirror cavity for spectroscopic distance measurement." Review of Scientific Instruments 87, no. 9 (September 2016): 093107. http://dx.doi.org/10.1063/1.4962681.

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Hu, H. T. "Comb filtering of noisy speech using overlap-and-add approach." Electronics Letters 34, no. 1 (1998): 16. http://dx.doi.org/10.1049/el:19980107.

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Dissertations / Theses on the topic "Comb filtering"

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Sadik, Amin, and not supplied. "Signal Processing Using Short Word-Length." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070523.163613.

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Recently short word-length (normally 1 bit or bits) processing has become a promising technique. However, there are unresolved issues in sigma-delta modulation, which is the basis for 1b/2b systems. These issues hindered the full adoption of single-bit techniues in industry. Among these problems is the stability of high-order modulators and the limit cycle behaviour. More importantly, there is no adaptive LMS structure of any kind in 1b/2b domain. The challenge in this problem is the harsh quantization that prevents straightforward LMS application. In this thesis, the focus has been made on three axes: designing new single-bit DSP applications, proposing novel approaches for stability analysis, and tacking the unresolved problems of 1b/2b adaptive filtering. Two structures for 1b digital comb filtering are proposed. A ternary DC blocker structure is also presented and performance is tested. We also proposed a single-bit multiplierless DC-blocking structure. The s tability of a single-bit high-order signma-delta modulator is studied under dc inputs. A new approach for stability analysis is proposed based on analogy with PLL analysis. Finally we succeeded in designing 1b/2b Wiener-like filtering and introduced (for the first time) three 1b/2b adaptive schemes.
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Silva, Claudio Fernandes Castanheira. "Dense WDM channel synthesis using optical frequency comb generation and locked laser filtering techniques." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399710.

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Edlund, Adam. "Implementation of continuous filtering frequency comb Vernier spectroscopy for continuous acquisition of spectra in a flame." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-142426.

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In this project laser absorption spectroscopy was performed on a flame in a Fabry-Pérot cavity, using an optical frequency comb. Optical frequency comb spectroscopy is a technique that allows broadband ultra-sensitive detection of molecular species in gas phase. Optical frequency combs are generated by femtosecond mode-locked lasers, which generate short pulses and whose spectrum consists of a comb of sharp laser lines covering a broad spectral range. Doing spectroscopy with optical frequency combs can hence be compared to measurements with thousand of synchronised continuous wave lasers simultaneously, which enables broadband sensitive measurements in short acquisition times. A Vernier spectrometer uses the filtering ability of the cavity to allow sequential transmission of parts of the frequency comb spectrum. Its technical simplicity and robustness make it a good candidate for measuring in turbulent environments. The aim of the project was to implement continuous-filtering Vernier spectroscopy in a setup for measuring absorption spectra in air and in a flame. This was done by using an Er:fiber femtosecond laser emitting in the near-infrared wavelength range and a Fabry-Pérot cavity containing the flame. The cavity, which consists of two highly reflective mirrors, lets the light of the comb interact with the molecules in the flame for each of the many round-trips it perform; thus increasing the sensitivity to absorption. An active locking mechanism was implemented to stabilize the coupling of the optical frequency comb to the cavity. The locking allowed multiple measurements to be averaged which reduced noise. A galvanometer scanner was added to the system which was used to measure a broad part of the comb spectrum. Hot water absorption lines were detected in the swept comb spectrum and a candidate absorption peak for OH absorption was recorded. The spectrometer today has opportunities for improvements. A frequency calibration should be implemented which is essential for making estimates of reactant/product concentrations in combustion processes.
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Vlček, Lukáš. "Směrování ve vysokorychlostních počítačových sítích." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220187.

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Goal of this master thesis is to introduce and bring up basics and principles of NetCOPE framework in many details using "first approach" method for exploration of its internal structures - mainly focusing on application core using VHDL for focus itself. Furthermore, this knowledge is used for design and implementation of filtration system for network traffic with more details within phase of design in VHDL language.
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Fioravanti, André Ricardo 1982. "Filtragem de sistemas discretos com parametros sujeitos a saltos markovianos." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259355.

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Orientador: Jose Claudio Geromel
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-10T01:06:21Z (GMT). No. of bitstreams: 1 Fioravanti_AndreRicardo_M.pdf: 793181 bytes, checksum: 6f60b78faabe194cc22f2cc3157f0d90 (MD5) Previous issue date: 2007
Resumo: Esta dissertação tem par principal objetivo o estudo do problema de projeto de filtros H2 e Hoo de sistemas lineares discretos com parâmetros sujeitos a saltos markovianos. Inicialmente, sob a hipótese de que o parâmetro da cadeia de Markov é mensurável, fornecemos a caracterização de todos os filtros tais que o erro de estimação é limitado por uma norma, produzindo a solução completa do problema de projeto dependente do modo da cadeia. Baseado neste resultado, consideramos o projeto do filtro robusto capaz de lidar com incertezas paramétricas. Em seguida, propomos um procedimento de projeto de filtros sem o conhecimento da cadeia. Todos os problemas de filtragem são expressos em termos de desigualdades matriciais lineares. Os resultados teóricos são ilustrados através de uma aplicação prática que consiste na comunicação de dados através de um canal markoviano
Abstract: This thesis addresses the H2 and Hoo filtering design problem of discrete-time Markov jump linear systems. First, under the assumption that the Markov parameter is measurable, we provide the characterization of all filters such that the estimation errar remains bounded by a given narm leveI, yielding the complete solution of the mode-dependent filtering design problem. Based on this result, a robust filter design to deal with convex bounded parameter uncertainty is considered. In the sequeI, a design procedure for modeindependent filtering design is proposed. All filters are designed by solving linear matrix inequalities. The theory is illustrated by means of a practical example, consisting the data communication through a markovian channel
Mestrado
Automação
Mestre em Engenharia Elétrica
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Sánchez, Delgado Albert Miquel. "Electric-Device Characterization for Interference Prediction and Mitigation by an Optimal Filtering Design." Doctoral thesis, Universitat Ramon Llull, 2010. http://hdl.handle.net/10803/9144.

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Les interferències de mode comú i diferencial que es propaguen en un cable de la xarxa elèctrica monofàsica s'acostumen a suprimir utilitzant els filtres de xarxa. Aquesta classe de filtres estan formats per xocs de mode comú, condensadors X i condensadors Y per a mitigar tant el mode comú com el mode diferencial. Tot i això, les metodologies actuals de disseny de filtres de xarxa presenten alguns inconvenients: els filtres es dissenyen per treballar en un entorn ideal amb impedàncies de 50 Ω i les atenuacions del mode comú i del mode diferencial s'analitzen de manera independent, sense considerar la conversió modal que es produeixen en les asimetries presents a la xarxa elèctrica, al dispositiu elèctric o al mateix filtre de xarxa. Aquests fets impliquen que les prediccions del comportament del filtre siguin inexactes i, conseqüentment, el filtre més adequat en una situació particular s'acaba majoritàriament escollint mitjançant la prova i error en llargues i costoses sessions de mesura. Per tal de millorar aquesta situació, aquest treball presenta:
- Nous sistemes de mesura i caracterització per modelar completament el comportament dels filtres de xarxa, xarxa elèctrica i dispositius elèctrics. Amb aquesta finalitat, s'introdueix una nova metodologia de caracterització: la caracterització modal, que confina el mode comú i el mode diferencial en ports diferents, proporcionant així informació sobre la propagació de la interferència modal. Aquesta informació pot ser d'utilitat a l'hora de seleccionar el filtre de xarxa adient.
- Una nova metodologia per a predir amb exactitud el nivell de les emissions conduïdes que un dispositiu elèctric introdueix a la xarxa elèctrica a través del filtre de xarxa. Aquesta metodologia està basada en les metodologies de caracterització presentades anteriorment. Caracteritzacions acurades permetran obtenir prediccions similars a les emissions conduïdes reals, evitant així llargues sessions de mesura.
- Noves metodologies de disseny de filtres de xarxa per aconseguir implementacions òptimes i de baix cost. En una primera proposta, els components dels filtres de xarxa (condensadors i xocs) es caracteritzen modalment per trobar la combinació que obté el filtratge desitjat amb el mínim nombre de components. Aquesta metodologia és millorada posteriorment utilitzant filtres de xarxa asimètrics, obtenint així un filtratge òptim del mode comú i del mode diferencial.
Tots els sistemes de mesura, així com les metodologies de caracterització, predicció i disseny, han estat provats amb èxit sobre equips reals.
Las interferencias de modo común y diferencial que se propagan en un cable de la red eléctrica monofásica se acostumbran a suprimir utilizando los filtros de red. Esta clase de filtros están formatos por choques de modo común, condensadores X y condensadores Y para mitigar tanto el modo común como el modo diferencial. Aún así, las metodologías actuales de diseño de filtros de red presentan algunos inconvenientes: los filtros se diseñan para trabajar en un entorno ideal con impedancias de 50 Ω y las atenuaciones del modo común y del modo diferencial se analizan de manera independiente, sin considerar la conversión modal que se producen en las asimetrías presentes en la red eléctrica, en el dispositivo eléctrico o en el mismo filtro de red. Estos hechos implican que las predicciones del comportamiento del filtro sean inexactas y, consecuentemente, el filtro más adecuado en una situación particular se acaba escogiendo mayoritariamente mediante la prueba y error en largas y costosas sesiones de medida. Para mejorar esta situación, este trabajo presenta:
- Nuevos sistemas de medida y caracterización para modelar completamente el comportamiento de los filtros de red, red eléctrica y dispositivos eléctricos. Con este objetivo, se introduce una nueva metodología de caracterización: la caracterización modal, que confina el modo común y el modo diferencial en puertos diferentes, proporcionando así información sobre la propagación de la interferencia modal. Esta información puede ser de utilidad a la hora de seleccionar el filtro de red adecuado.
- Una nueva metodología para predecir con exactitud el nivel de las emisiones conducidas que un dispositivo eléctrico introduce en la red eléctrica a través del filtro de red. Esta metodología está basada en las metodologías de caracterización presentadas anteriormente. Caracterizaciones precisas permitirán obtener predicciones similares a las emisiones conducidas reales, evitando así largas sesiones de medida.
- Nuevas metodologías de diseño de filtros de red para conseguir implementaciones óptimas y de bajo coste. En una primera propuesta, los componentes de los filtros de red (condensadores y choques) se caracterizan modalmente para encontrar la combinación que obtiene el filtraje deseado con el mínimo número de componentes. Esta metodología es mejorada posteriormente utilizando filtros de red asimétricos, obteniendo así un filtraje óptimo del modo común y del modo diferencial.
Todos los sistemas de medida, así como las metodologías de caracterización, predicción y diseño, han sido probados con éxito sobre equipos reales.
The common mode and differential mode interference propagated through the single-phase power-line cable is usually suppressed with power-line filters. This kind of filters is composed by common-mode chokes, X capacitors and Y capacitors to mitigate both the common mode and the differential mode. However, the present-day power-line filter design methodologies present some disadvantages: they are designed to be placed in an ideal 50-Ω system and the common mode and differential mode attenuations are analyzed independently, without considering the mode conversion that can be produced by asymmetries in the power-line filter, in the power-line network or in the electric device. These facts lead to inaccurate predictions of the power-line filter behavior and, consequently, the suitable filter is usually selected by trial and error in long and expensive measurement sessions. In order to improve this situation, this work presents:
- New measurement systems and characterization methodologies to completely model the behavior of power-line filters, power-line networks and electric devices. To this end, a new characterization methodology is presented: the modal characterization, which confines the common mode and the differential mode into a different port and provides the information about the propagation of the modal interference, information that can be useful to select the suitable filter for its mitigation.
- A new methodology to accurately predict the level of conducted emissions that an electric device supplies to the power-line network through its power-line filter, based on the measurement systems and characterization methodologies presented before. Accurate characterizations will allow predictions similar to the actual conducted emissions, avoiding long measurement sessions.
- New design methodologies of power-line filters to achieve optimal and low cost implementations. In a first proposal, the components of the power-line filters are modally characterized to find, by computation, the combination that gets the desired filtering response with the minimum number of components. This methodology is further improved by using asymmetric power-line filters, obtaining an optimal mitigation of the common and differential mode.
All measurement systems, as well as characterization, prediction and designing methodologies, have been successfully tested on actual devices.
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Furuie, Sérgio Shiguemi. "Reconstrução tomográfica de imagens com rudo poisson: estimativa das projeções´." Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-14122017-111814/.

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A reconstrução tomográfica de imagens com ruído Poisson tem grandes aplicações em medicina nuclear. A demanda por informações mais complexas, como por exemplo, várias secções de um órgão, e a necessidade de reduzir a dosagem radioativa a que o paciente é submetido, requerem métodos adequados para a reconstrução de imagem com baixa contagem, no caso, baixa relação sinal/ruído. A abordagem estatística, utilizando a máxima verossimilhança (ML) e o algoritmo Expectation-Maximization (EM), produz melhores resultados do que os métodos tradicionais, pois incorpora a natureza estatística do ruído no seu modelo. A presente tese apresenta uma solução alternativa, considerando também o modelo de ruído Poisson, que produz resultados comparáveis ao do ML-EM, porém com custo computacional bem menor. A metodologia proposta consiste, basicamente, em se estimar as projeções considerando o modelo de formação das projeções ruidosas, antes do processo da reconstrução. São discutidos vários estimadores otimizados, inclusive Bayesianos. Em especial, é mostrado que a transformação de ruído Poisson em ruído aditivo Gaussiano e independente do sinal (transformação de Anscombe), conjugada à estimativa, produz bons resultados. Se as projeções puderem ser consideradas, aproximadamente, transformadas de Radon da imagem a ser reconstruída, então pode ser aplicado um dos métodos da transformada para a reconstrução tomográfica. Dentre estes métodos, o da aplicação direta da transformada de Fourier foi avaliado mais detalhadamente devido ao seu grande potencial para reconstruções rápidas com processamento vetorial e processamento paralelo. A avaliação do método proposto foi realizada através de simulações, onde foram geradas as imagens originais e as projeções com ruído Poisson. Os resultados foramcomparados com métodos clássicos como a filtragem-retroprojeção, o ART e o ML-EM. Em particular, a transformação de Anscombe conjungada ao estimador heurístico (filtro de Maeda), mostrou resultados próximos aos do ML-EM, porém com tempo de processamento bem menor. Os resultados obtidos mostram a viabilidade da presente proposta vir a ser utilizada em aplicações clínicas na medicina nuclear.
Tomographic reconstruction of images with Poisson noise is in important problem in nuclear medicine. The need for more complete information, like the reconstruction of several sections of an organ, and the necessity to reduce patient absorbed radioactivity, suggest better methods to reconstruct images with low-count and low signal-to-noise ratio. Statistical approaches using Maximum Likelihood (ML) and the Expectation-Maximization (EM) algorithm lead to better results than classical methods, since ML-EM considers in its model the stochastic nature of the noise. This thesis presents an alternative solution, also using a Poisson noise model, that produces similar results as compared to ML-EM, but with much less computational cost. The proposed technique basically consists of projection estimation before reconstruction, taking into account a model for the formation of the noisy projections. Several optimal and Bayesian estimators are analysed. It is shown that the transformation of Poisson noise into Gaussian additive and independent noise (Anscombe Transformation), followed by estimation, yields good results. If the projection can be assumed as Radon transform of the image to be reconstructed, then it is possible to reconstruct using one of the transform methods. Among these methods, the Direct Fourier Method was analysed in detail, due to its applicability for fast reconstruction using array processors and parallel processing. Computer simulations were used in order to access this proposed technique. Phantoms and phantom projections with Poisson noise were generated. The results were compared with traditional methods like Filtering-Backprojection, Algebraic Rconstruction Technique (ART) and ML-EM. Specifically, the Anscombe transformation together with a heuristic estimator (Maeda\'s filter) produced results comparable to ML-EM, but spending only a fraction of the processing time.
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Isaia, Filho Eduardo. "Uma metodologia para computação com DNA." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/16662.

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A computação com DNA é um campo da Bioinformática que, através da manipulação de seqüências de DNA, busca a solução de problemas. Em 1994, o matemático Leonard Adleman, utilizando operações biológicas e manipulação de seqüências de DNA, solucionou uma instância de um problema intratável pela computação convencional, estabelecendo assim, o início da computação com DNA. Desde então, uma série de problemas combinatoriais vem sendo solucionada através deste modelo de programação. Este trabalho analisa a computação com DNA, com o objetivo de traçar algumas linhas básicas para quem deseja programar nesse ambiente. Para isso, são apresentadas algumas vantagens e desvantagens da computação com DNA e, também, alguns de seus métodos de programação encontrados na literatura. Dentre os métodos estudados, o método de filtragem parece ser o mais promissor e, por isso, uma metodologia de programação, através deste método, é estabelecida. Para ilustrar o método de Filtragem Seqüencial, são mostrados alguns exemplos de problemas solucionados a partir deste método.
DNA computing is a field of Bioinformatics that, through the manipulation of DNA sequences, looks for the solution of problems. In 1994 the mathematician Leonard Adleman, using biological operations and DNA sequences manipulation, solved an instance of a problem considered as intractable by the conventional computation, thus establishing the beginning of the DNA computing. Since then, a series of combinatorial problems were solved through this model of programming. This work studies the DNA computing, aiming to present some basic guide lines for those people interested in this field. Advantages and disadvantages of the DNA computing are contrasted and some methods of programming found in literature are presented. Amongst the studied methods, the filtering method appears to be the most promising and for this reason it was chosen to establish a programming methodology. To illustrate the sequential filtering method, some examples of problems solved by this method are shown.
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Burt, Phillip Mark Seymour. "Um estudo sobre filtros IIR adaptativos com aplicação a uma estrutura polifásica." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-14122017-134500/.

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Neste trabalho faz-se um estudo sobre filtros IIR adaptativos e é apresentada uma estrutura polifásica para filtragem IIR adaptativa, que, em troca de um aumento de complexidade computacional, pode apresentar características mais favoráveis do que a estrutura direta comumente usada. O aumento da complexidade computacional, relativamente a um algoritmo do tipo newton, por exemplo, é pequeno. Apresenta-se uma análise dos efeitos da proximidade ao círculo unitário dos pólos do sistema sendo modelado. Um dos efeitos considerados é o comportamento limite do condicionamento da matriz de estados associada ao algoritmo de adaptação. São considerados algoritmos de adaptação de passo constante de uso comum para filtros IIR adaptativos. O método utilizado é particularmente útil para a verificação do efeito da posição dos pólos do sistema sendo modelado e também para a introdução de certas restrições ao mesmo, como, por exemplo, norma L2 fixa e resposta em freqüência passa-tudo. Um resultado interessante é que a única situação, entre as testadas, em que o condicionamento da matriz mencionada não tende a infinito quando um número qualquer de polosndo sistema sendo modelado H(z) se aproxima da circunferência unitária, é quando H(z) é passa-tudo e emprega-se o algoritmo PLR. São analisadas também a superfície de erro e a superfície de erro reduzida para filtros IIR adaptativos. Mostra-se que, quando o sistema sendo modelado possui polos próximos à circunferência unitária, a superfície de erro reduzida apresenta regiões planas com erro quadrático médio elevado. A existência destas regiões resulta em uma baixa velocidade de convergência global de algoritmos de passo constante. A partir da decomposição em valores singulares (SVD) da forma de Hankel do sistema sendo modelado, é apresentada também uma decomposição da superfície de erro reduzida, a partir da qual pode-se obter uma separaçãoparcial dos efeitos do sistema sendo modelado e da forma de realização do filtro adaptativo. Uma estrutura polifásica para filtragem IIR adaptativa é apresentada e seu desempenho é comparado com o de filtros IIR adaptativos na forma direta. Mostra-se o possível ganho da estrutura polifásica quanto à velocidade de convergência local e quanto às características da superfície de erro reduzida e à velocidade de convergência global. Demonstra-se, para a estrutura polifásica, que, com entrada branca e modelamento suficiente, todos os pontos estacionários da superfície de erro são mínimos globais da mesma. Este resultado não decorre diretamente de propriedades análogas relativas à estrutura direta, já conhecidas. Tudo para a estrutura direta quanto para a estrutura polifásica, são apresentados os resultados de várias simulações dos algoritmos de adaptação considerados.
A study on IRR adaptive filters and polyphase structure for IIR adaptive filtering are presented. In exchange for an increase in computational complexity, which is small if compared to Newton algorithms, the polyphaser structure may exhibit a better performance than direct structures. An analysis of the effects of the proximity to the unit circle of the modelled system\'s poles is presented. One of the considered points is the limiting behavior of the condition of the state matrix related to the adaptive algorithm. Commonly used constant gain algorithms are considered. The method of analysis is specially usefull for verifying the effects of the position of the system\'s poles and also for introducing certain restrictions to the system, as fixed L2 norm and all-pass frequency response. An interesting result is that, among the situations that were tested, the only one in which the condition of the aforementioned matrix does not tend to infinity as the poles of the modelled system H(z) tend to the unit circle is when H)z) is all-pass and the PLR algorithm is employed. The error surface and the reduced error surface for IIR adaptive filters are also analyzed. It is shown that the modelled system has poles close to the unit circle the reduced error surface presents flat regions with high mean square error. The presence of these flat regions results in low global convergence speed for constant gain adaptive algorithms. Based on the singular value decomposition (SVD) of the modelled system\'s Hankel form, a decomposition of the reduced error surface is also presented. In it there exists a partial separation of the effects of the system and the adaptive filter\'s structure. A polyphaser structure for IIR adaptive filtering is presented and its performance is compared to the performance of the direct structure. The gain in local convergence and global convergencespeed, as well as the better behavior of the reduced error surface which may be attained , are shown. It is demonstrated, for the polyphaser structure, that, with while input and sufficient modelling, all the stationary points of the error surface are global minima. This result does not follow directly from similar well known results for the direct structure. Simulation results for the considered algorithms are also presented.
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Filho, Antonio Carlos da Silva Senra. "Filtro de difusão anisotrópica anômala como método de melhoramento de imagens de ressonância magnética nuclear ponderada em difusão." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-20082013-161108/.

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Métodos de suavização através de processos de difusão é frequentemente utilizado como etapa prévia em diferentes procedimentos em imagens. Apesar da difusão anômala ser um processo físico conhecido, ainda não é aplicada à suavização de imagens como a difusão clássica. Esta dissertação propõe e relata a implementação e avaliação de filtros de difusão anômala, tanto isotrópico quanto anisotrópico, como um método de melhoramento em imagens ponderadas em difusão (DWI) e imagens de tensor de difusão (DTI) dentro do imageamento por ressonãncia magnética (MRI). Aqui propõe-se generalizar a difusão anisotrópica e isotrópica com o conceito de difusão anômala em processamento de imagens. Como metodologia implementou-se computacionalmente as equações de difusão bidimensional e aplicou às imagens MRI para avaliar o seu potencial como filtro de melhoramento. Foram utilizadas imagens de ressonância magnética de aquisição DTI em voluntários saudáveis. Os resultados obtidos neste estudo foram a verificação que métodos baseados em difusão anômala melhoram a qualidade em processamento das imagens DTI e DWI quando observadas medidas de qualidade como a relação sinal ruído (SNR) e índice de similaridade estrutural (SSIM), e assim determinou-se parâmetros ótimos para as diferentes imagens e situações que foram avaliadas em função dos seus parâmetros de controle, em especial o parâmetro anômalo, chamado de q. Os resultados apresentados aqui permitem prever não apenas uma melhora na qualidade das imagens DTI e DWI resultantes do processamento proposto, como também possível redução de repetições na sequência de aquisição de MRI para um SNR predeterminado.
Smoothing methods through diffusion processes is often used as a preliminary step in different procedures in images. Although the anomalous diffusion is a known physical process, it is not applied to image smoothing as the classical diffusion. This paper proposes and describes implementation and evaluation of anomalous diffusion filters, both isotropic and anisotropic, as a method of improving on diffusion-weighted images (DWI) and diffusion tensor images (DTI) within the magnetic resonance imaging (MRI). Hereby is proposed to generalize the isotropic and anisotropic diffusion with the concept of anomalous diffusion in image processing. The methodology is implemented computationally as bidimensional diffusion equations and applied to MRI images to evaluate its potential as a filter for quality improvement. We used DTI and DWI imaging to acquire from healthy volunteers as image set. The results of this study verified that methods based on anomalous diffusion improved DWI and DTI image processing when observed quality measures such as signal to noise ratio (SNR) and structural similarity index (SSIM), and determined filter optimal parameters for different images and situations evaluated in terms of their control parameters, particularly the anomalous parameter, called q. The results presented here can predict not only an improvement in the quality of DWI and DTI images resulting from the proposed method, and additionally the possible reduction of repetitions following acquisition of MRI for a predetermined SNR.
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Books on the topic "Comb filtering"

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Monsefi, Reza. An interactive digital simulation of a 'FSK' telemetry system, utilizing on-line real-time comb-filtering or fast fourier transform methods for reconstruction of binary data. Salford: University of Salford, 1987.

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van, José. News. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190889760.003.0004.

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This chapter examines how the advent of data-driven publishers, such as BuzzFeed and the Huffington Post, as well as the rise of the Big Five platforms, have shaken the news sector’s economic, technical, and social foundations. The proliferation of online audience metrics and algorithmic filtering, promoting the personalization of news and advertisements, has fundamentally transformed how news is produced, circulated, and monetized. The triangular content–audiences–advertising configuration that constituted the legacy news industry is unbundled and rebundled through online platforms. As a consequence, the professional practices and institutional standards once set by legacy news organizations are seriously challenged. Key public values, such as journalistic independence and the trustworthiness of news, have come under scrutiny as new online players in this sector reconfigure the conditions of production and distribution.
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Feldman, Robert M., and Nicholas P. Bell, eds. Complications of Glaucoma Surgery. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780195382365.001.0001.

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Glaucoma surgery is difficult and fraught with complications. Some complications are common and mild, while others are rare and/or vision threatening. However, good outcomes are still likely if those complications encountered are managed properly. This book is intended for those surgeons wishing to improve their skills and abilities to manage difficult problems that will come up during the care of glaucoma patients. Comprising seven comprehensive sections, chapters in this volume address outflow mechanisms after glaucoma surgery, wound healing processes and modulators, complications in filtering surgery, tube shunt implantation, and angle procedures, among other topics. The authors of each chapter provide surgical and clinical pearls not only for managing difficulties but in preventing them as well. Additionally, because each surgeon has their own way of addressing a particular situation, there is commentary at the end of each chapter to provide another opinion or strategy for dealing with a particular surgical scenario. Cross-referencing is provided throughout this book to direct the reader to as many helpful sections as possible. Both thorough and highly-illustrative, this book will help both new and experienced glaucoma surgeons deal with complications and provide successful results for their patients.
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Book chapters on the topic "Comb filtering"

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Park, Jeong-Sik. "Advanced Comb Filtering for Robust Speech Recognition." In Lecture Notes in Electrical Engineering, 31–36. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-7262-5_4.

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El Kadmiri, Ilyass, Youssef Ben-Ali, Abdelaziz Ouariach, Aissam Khaled, and Driss Bria. "Double Frequency Filtering in One Dimensional Comb-Like Phononic Structure Containing a Segment Defect." In Lecture Notes in Mechanical Engineering, 13–21. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-62199-5_2.

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Stuchlík, Evžen. "Feeding behaviour and morphology of filtering combs of Daphnia galeata." In Biology of Cladocera, 155–67. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-017-0918-7_14.

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Milic, Ljiljana. "Comb-Based Filters for Sampling Rate Conversion." In Multirate Filtering for Digital Signal Processing, 316–46. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-178-0.ch011.

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Comb filters are developed from the structures based on the moving average (boxcar) filter. The combbased filter has unity-valued coefficients and, therefore, can be implemented without multipliers. This filter class can operate at high frequencies and is suitable for a single-chip VLSI implementation. The main applications are in communication systems such as software radio and satellite communications. In this chapter, we introduce first the concept of the basic comb filter and discuss its properties. Then, we present the structures of the comb-based decimators and interpolators, discuss the corresponding frequency responses, and demonstrate the overall two-stage decimator constructed as the cascade of a comb decimator and an FIR decimator. In the next section, we expose the application of the polyphase implementation structure, which is aimed to reduce the power dissipation. We consider techniques for sharpening the original comb filter magnitude response and emphasize an approach that modifies the filter transfer function in a manner to provide a sharpened filter operating at the lowest possible sampling rate. Finally, we give a brief presentation of the modified comb filter based on the zero-rotation approach. Chapter concludes with several MATLAB Exercises for the individual study. The reference list at the end of the chapter includes the topics of interest for further research.
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Dolecek, Gordana Jovanovic. "Methods for Improving Alias Rejections in Comb Filters." In Encyclopedia of Information Science and Technology, Fourth Edition, 4746–60. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2255-3.ch412.

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Downsampling is the process of decreasing the sampling rate of signal by an integer. This process may introduce the unwanted spectrum replica called aliasing. To avoid aliasing the signal must be filtered by decimation filter prior downsampling. Decimation consists of filtering and downsampling. The most simple decimation filter is comb filter usually used in the first stage of decimation. However, comb filter does not provide a good aliasing rejection. This paper presents the methods for improving alias rejection of comb filters. The methods are based on comb zero rotation, cosine filters, Chebyshev polynomials, and cascade of combs with different parameters.
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Dolecek, Gordana Jovanovic. "Methods for Improving Alias Rejections in Comb Filters." In Advanced Methodologies and Technologies in Artificial Intelligence, Computer Simulation, and Human-Computer Interaction, 891–909. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7368-5.ch066.

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Downsampling is the process of decreasing the sampling rate of signal by an integer. This process may introduce the unwanted spectrum replica called aliasing. To avoid aliasing, the signal must be filtered by decimation filter prior to downsampling. Decimation consists of filtering and downsampling. The simplest decimation filter is comb filter usually used in the first stage of decimation. However, comb filter does not provide a good aliasing rejection. This chapter presents methods for improving alias rejection of comb filters. The methods are based on comb zero rotation, cosine filters, Chebyshev polynomials, and cascade of combs with different parameters.
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Mohammadian, Masoud, and Ric Jentzsch. "Computational Intelligence Techniques Driven Intelligent Agents for Web Data Mining and Information Retrieval." In Data Warehousing and Mining, 1435–45. IGI Global, 2008. http://dx.doi.org/10.4018/978-1-59904-951-9.ch081.

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The World Wide Web has added an abundance of data and information to the complexity of information for disseminators and users alike. With this complexity has come the problem of finding useful and relevant information. There is a need for improved and intelligent search and retrieval engines. Current search engines are primarily passive tools. To improve the results returned by searches, intelligent agents and other technology have the potential, when used with existing search and retrieval engines, to provide a more comprehensive search with an improved performance. This research provides the building blocks for integrating intelligent agents with current search engines. It shows how an intelligent system can be constructed to assist in better information filtering, gathering and retrieval. The research is unique in the way the intelligent agents are directed and in how computational intelligence techniques (such as evolutionary computing and fuzzy logic) and intelligent agents are combined to improve information filtering and retrieval. Fuzzy logic is used to access the performance of the system and provide evolutionary computing with the necessary information to carry out its search.
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Mohammadian, Masoud, and Ric Jentzsch. "Computational Intelligence Techniques Driven Intelligent Agents for Web Data Mining and Information Retrieval." In Intelligent Agents for Data Mining and Information Retrieval, 15–30. IGI Global, 2004. http://dx.doi.org/10.4018/978-1-59140-194-0.ch002.

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The World Wide Web has added an abundance of data and information to the complexity of information for disseminators and users alike. With this complexity has come the problem of finding useful and relevant information. There is a need for improved and intelligent search and retrieval engines. Current search engines are primarily passive tools. To improve the results returned by searches, intelligent agents and other technology have the potential, when used with existing search and retrieval engines, to provide a more comprehensive search with an improved performance. This research provides the building blocks for integrating intelligent agents with current search engines. It shows how an intelligent system can be constructed to assist in better information filtering, gathering and retrieval. The research is unique in the way the intelligent agents are directed and in how computational intelligence techniques (such as evolutionary computing and fuzzy logic) and intelligent agents are combined to improve information filtering and retrieval. Fuzzy logic is used to access the performance of the system and provide evolutionary computing with the necessary information to carry out its search.
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Mandić, Danilo. "Mafia Filter." In Gangsters and Other Statesmen, 63–81. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691187884.003.0004.

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This chapter compares the organized criminal filtering of regional smuggling opportunities (in drugs and arms) into separatist movement benefit. For separatists, it is preferable to have transnational smuggling in their region than not. This is trivial, almost axiomatic. Movements are denied formal channels for various resources they sorely need — money, arms, fighters, and propaganda channels. What they cannot procure within host state borders, they must smuggle across them. When separatists have the fortuitous circumstance of regional smuggling routes, it is only natural they exploit it. But the advantage does not come automatically. Mafia capacity and predisposition in these rackets at critical junctures — 1999 in Kosovo and 2008 in South Ossetia — enhanced and stagnated separatism, respectively.
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Kefalakis, Nikos, and John Soldatos. "An Integrated Development Environment for RFID Applications." In Application Development and Design, 455–78. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3422-8.ch019.

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In recent years we have witnessed a proliferation of RFID (Radio Frequency Identification) middleware systems and projects (including several open source projects), which are extensively used to support the emerging wave of RFID applications. Some of the RFID middleware projects come with simple tools, which facilitate the application development, configuration, and deployment processes. However, these tools tend to be fragmented since they address only part of an RFID system (such as the filtering of tag streams and/or the generation of business events). In this chapter, the authors introduce an Integrated Development Environment (IDE) for RFID applications, which addresses multiple parts of an RFID application, while at the same time supporting the full application development lifecycle (i.e. design, development, deployment, and testing of RFID applications). The introduced IDE comprises a wide range of tools, which have been implemented as modular plug-ins to an Eclipse-based environment. The various tools enable application development, deployment, testing, and configurations over the middleware infrastructure established by the AspireRFID (AspireRFID Consortium, 2013), and their evaluation has proven that they can significantly ease RFID application development.
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Conference papers on the topic "Comb filtering"

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Rasmussen, J. L. "New method of FIR comb filtering." In 2012 46th Asilomar Conference on Signals, Systems and Computers. IEEE, 2012. http://dx.doi.org/10.1109/acssc.2012.6489122.

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Prange, Jansen, and Horn. "Adaptiver comb-filtering using neural networks." In 1998 International Conference on Consumer Electronics. IEEE, 1997. http://dx.doi.org/10.1109/icce.1997.626019.

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Ben-Ali, Youssef, Zakaria Tahri, Abdelaziz Ouariach, and Driss Bria. "Double Frequency Filtering by Photonic Comb-Like." In 2018 International Symposium on Advanced Electrical and Communication Technologies (ISAECT). IEEE, 2018. http://dx.doi.org/10.1109/isaect.2018.8618798.

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Trask, Lawrence, R. Bustos-Ramirez, C. Shipurkar, S. V. Pericherla, and Peter J. Delfyett. "Hyperfine Filtering of an Electro-Optic Modulated Comb." In 2020 IEEE Photonics Conference (IPC). IEEE, 2020. http://dx.doi.org/10.1109/ipc47351.2020.9252486.

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McEachen II, John C., Arye Nehorai, and James S. Duncan. "Analysis of cardiac motion with recursive comb filtering." In SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, edited by Fred L. Bookstein, James S. Duncan, Nicholas Lange, and David C. Wilson. SPIE, 1994. http://dx.doi.org/10.1117/12.179270.

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Demiroglu, Cenk, David V. Anderson, Mark A. Clements, and Thomas Barnwell. "Multi-Sensor Spectro-Temporal Comb Filtering for Speech Enhancement." In 2007 IEEE International Conference on Acoustics, Speech, and Signal Processing. IEEE, 2007. http://dx.doi.org/10.1109/icassp.2007.366981.

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Wang, Keming. "Comb-Filtering-Based Signal Reconstruction for Bearing Fault Detection." In 2007 2nd IEEE Conference on Industrial Electronics and Applications. IEEE, 2007. http://dx.doi.org/10.1109/iciea.2007.4318839.

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Chang, Guoqing, Chih-Hao Li, David F. Phillips, Ronald L. Walsworth, and Franz X. Kärtner. "Broadband, large-spacing frequency-comb employing complementary interleavers for mode filtering." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2011. http://dx.doi.org/10.1364/cleo_si.2011.cwq4.

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Cai, Yu, Jianping Yuan, Chaohuan Hou, Jun Yang, and Bian Wu. "Harmonic Enhancement with Noise Reduction of Speech Signal by Comb Filtering." In 2009 2nd International Congress on Image and Signal Processing (CISP). IEEE, 2009. http://dx.doi.org/10.1109/cisp.2009.5303823.

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Long, C. M., R. Wu, F. Ferdous, V. R. Supradeepa, E. Hamidi, D. E. Leaird, and A. M. Weiner. "Dual-comb microwave photonic filtering with unprecedented 40-ns tuning speed." In 2011 IEEE Photonics Conference (IPC). IEEE, 2011. http://dx.doi.org/10.1109/pho.2011.6110467.

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