Relevant bibliographies by topics / Coherence time

Academic literature on the topic 'Coherence time'

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Published: 4 June 2021
Last updated: 10 March 2023

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Journal articles on the topic "Coherence time"

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Le, Thai-Hoa, and Dong-Anh Nguyen. "TEMPORO-SPECTRAL COHERENT STRUCTURE OF TURBULENCE AND PRESSURE USING FOURIER AND WAVELET TRANSFORMS." ASEAN Journal on Science and Technology for Development 25, no. 2 (November 22, 2017): 405–17. http://dx.doi.org/10.29037/ajstd.271.

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Studying the spatial distribution in coherent fields such as turbulent and turbulent-induced force ones is important to model and evaluate turbulent-induced forces and response of structures on the turbulent flows. Turbulent field-based coherent function is commonly used for the spatial distribution characteristic of induced forces in the frequency domain. This paper will focus to study spectral coherent structure of turbulence and forces in not only the frequency domain using conventional Fourier transform-based coherence, but also temporo-spectral coherent one in the time-frequency plane thanks to wavelet transform-based coherence for more understanding of the turbulence and force coherences and their spatial distributions. Effects of spanwise separations, bluff body flow and flow conditions on coherent structures of turbulence and induced pressure, comparison between turbulence and pressure coherences as well as intermittency of coherent structure in the time-frequency plane will be investigated here.
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Kobayashi, Yuki, and Stephen R. Leone. "Characterizing coherences in chemical dynamics with attosecond time-resolved x-ray absorption spectroscopy." Journal of Chemical Physics 157, no. 18 (November 14, 2022): 180901. http://dx.doi.org/10.1063/5.0119942.

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Coherence can drive wave-like motion of electrons and nuclei in photoexcited systems, which can yield fast and efficient ways to exert materials’ functionalities beyond the thermodynamic limit. The search for coherent phenomena has been a central topic in chemical physics although their direct characterization is often elusive. Here, we highlight recent advances in time-resolved x-ray absorption spectroscopy (tr-XAS) to investigate coherent phenomena, especially those that utilize the eminent light source of isolated attosecond pulses. The unparalleled time and state sensitivities of tr-XAS in tandem with the unique element specificity render the method suitable to study valence electronic dynamics in a wide variety of materials. The latest studies have demonstrated the capabilities of tr-XAS to characterize coupled electronic–structural coherence in small molecules and coherent light–matter interactions of core-excited excitons in solids. We address current opportunities and challenges in the exploration of coherent phenomena, with potential applications for energy- and bio-related systems, potential crossings, strongly driven solids, and quantum materials. With the ongoing developments in both theory and light sources, tr-XAS holds great promise for revealing the role of coherences in chemical dynamics.
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Ma, Tian, and Erik M. Bollt. "Shape Coherence and Finite-Time Curvature Evolution." International Journal of Bifurcation and Chaos 25, no. 05 (May 2015): 1550076. http://dx.doi.org/10.1142/s0218127415500765.

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We introduce a definition of finite-time curvature evolution along with our recent study on shape coherence in nonautonomous dynamical systems. Comparing to slow evolving curvature preserving the shape, large curvature growth points reveal the dramatic change on shape such as the folding behaviors in a system. Closed trough curves of low finite-time curvature (FTC) evolution field indicate the existence of shape coherent sets, and troughs in the field indicate the most significant shape coherence. Here, we will demonstrate these properties of the FTC, as well as contrast to the popular Finite-Time Lyapunov Exponent (FTLE) computation, often used to indicate hyperbolic material curves as Lagrangian Coherent Structures (LCS). We show that often the FTC troughs are in close proximity to the FTLE ridges, but in other scenarios, the FTC indicates entirely different regions.
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GÜLERCE, MUSTAFA, and GAZANFER ÜNAL. "FORECASTING OF OIL AND AGRICULTURAL COMMODITY PRICES: VARMA VERSUS ARMA." Annals of Financial Economics 12, no. 03 (September 2017): 1750012. http://dx.doi.org/10.1142/s2010495217500129.

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The aim of this paper is to show that the estimates made with vector autoregressive–moving-average (ARMA) models based on the coherent time intervals of the multiple time series give more precise results than the univariate case. The previous literature on dynamic correlations (co-movement) in between food and energy prices has mixed results and mainly based on parametric approaches. Therefore, partial wavelet coherence (PWC) and multiple wavelet coherence (MWC) methods are used, respectively, to uncover the coherency simultaneously for time and frequency domains. In our study; world oil, corn, soybeans, wheat and sugar prices are examined instead of the return and volatility relationship between oil and agricultural commodities due to model-free approach of wavelet analysis.
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Naik, Dinesh N., Takahiro Ezawa, Yoko Miyamoto, and Mitsuo Takeda. "Real-time coherence holography." Optics Express 18, no. 13 (June 11, 2010): 13782. http://dx.doi.org/10.1364/oe.18.013782.

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Wang, L. J., X. Y. Zou, and L. Mandel. "Time-varying induced coherence." Journal of the Optical Society of America B 9, no. 4 (April 1, 1992): 605. http://dx.doi.org/10.1364/josab.9.000605.

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Kohles, N., P. Aechtner, and A. Laubereau. "The “coherence peak” in time-resolved coherent Raman scattering." Optics Communications 65, no. 5 (March 1988): 391–96. http://dx.doi.org/10.1016/0030-4018(88)90110-1.

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Villarroya-Carpio, Arturo, and Juan M. Lopez-Sanchez. "Multi-Annual Evaluation of Time Series of Sentinel-1 Interferometric Coherence as a Tool for Crop Monitoring." Sensors 23, no. 4 (February 7, 2023): 1833. http://dx.doi.org/10.3390/s23041833.

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Interferometric coherence from SAR data is a tool used in a variety of Earth observation applications. In the context of crop monitoring, vegetation indices are commonly used to describe crop dynamics. The most frequently used vegetation indices based on radar data are constructed using the backscattered intensity at different polarimetric channels. As coherence is sensitive to the changes in the scene caused by vegetation and its evolution, it may potentially be used as an alternative tool in this context. The objective of this work is to evaluate the potential of using Sentinel-1 interferometric coherence for this purpose. The study area is an agricultural region in Sevilla, Spain, mainly covered by 18 different crops. Time series of different backscatter-based radar vegetation indices and the coherence amplitude for both VV and VH channels from Sentinel-1 were compared to the NDVI derived from Sentinel-2 imagery for a 5-year period, from 2017 to 2021. The correlations between the series were studied both during and outside the growing season of the crops. Additionally, the use of the ratio of the two coherences measured at both polarimetric channels was explored. The results show that the coherence is generally well correlated with the NDVI across all seasons. The ratio between coherences at each channel is a potential alternative to the separate channels when the analysis is not restricted to the growing season of the crop, as its year-long temporal evolution more closely resembles that of the NDVI. Coherence and backscatter can be used as complementary sources of information, as backscatter-based indices describe the evolution of certain crops better than coherence.
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Schwickert, David, Marco Ruberti, Přemysl Kolorenč, Andreas Przystawik, Slawomir Skruszewicz, Malte Sumfleth, Markus Braune, et al. "Charge-induced chemical dynamics in glycine probed with time-resolved Auger electron spectroscopy." Structural Dynamics 9, no. 6 (November 2022): 064301. http://dx.doi.org/10.1063/4.0000165.

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In the present contribution, we use x-rays to monitor charge-induced chemical dynamics in the photoionized amino acid glycine with femtosecond time resolution. The outgoing photoelectron leaves behind the cation in a coherent superposition of quantum mechanical eigenstates. Delayed x-ray pulses track the induced coherence through resonant x-ray absorption that induces Auger decay. Temporal modulation of the Auger electron signal correlated with specific ions is observed, which is governed by the initial electronic coherence and subsequent vibronic coupling to nuclear degrees of freedom. In the time-resolved x-ray absorption measurement, we monitor the time-frequency spectra of the resulting many-body quantum wave packets for a period of 175 fs along different reaction coordinates. Our experiment proves that by measuring specific fragments associated with the glycine dication as a function of the pump-probe delay, one can selectively probe electronic coherences at early times associated with a few distinguishable components of the broad electronic wave packet created initially by the pump pulse in the cation. The corresponding coherent superpositions formed by subsets of electronic eigenstates and evolving along parallel dynamical pathways show different phases and time periods in the range of [Formula: see text] and [Formula: see text] fs. Furthermore, for long delays, the data allow us to pinpoint the driving vibrational modes of chemical dynamics mediating charge-induced bond cleavage along different reaction coordinates.
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Xiang, Wei, Rui Zhang, Guoxiang Liu, Xiaowen Wang, Wenfei Mao, Bo Zhang, Yin Fu, and Tingting Wu. "Saline-Soil Deformation Extraction Based on an Improved Time-Series InSAR Approach." ISPRS International Journal of Geo-Information 10, no. 3 (February 27, 2021): 112. http://dx.doi.org/10.3390/ijgi10030112.

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Significant seasonal fluctuations could occur in the regional scattering characteristics and surface deformation of saline soil, and cause decorrelation, which limits the application of the conventional time-series InSAR (TS-InSAR). For extending the saline-soil deformation monitoring capability, this paper presents an improved TS-InSAR approach, based on the interferometric coherence statistics and high-coherence interferogram refinement. By constructing a network of the refined interferograms, high-accuracy ground deformation can be extracted through the weighted least square estimation and the coherent target refinement. To extract the high-accuracy deformation of a representative saline soil area in the Qarhan Salt Lake, 119 C-band Sentinel-1A images collected between May 2015 and May 2020 are selected as the data source. Subsequently, 845 refined interferograms are selected from all possible interferograms to conduct the network inversion, based on the related thresholds (the temporal baseline <49 days, the average spatial coherences >0.5, respectively). Compared with the conventional TS-InSAR measurements, both the accuracy and reliability of the extracted deformation results of the saline soil increased dramatically. Furthermore, the testing results indicate that the improved TS-InSAR method has advantages on the deformation extraction in the saline soil region, and is adaptive to reflecting the typical seasonal variations of the saline soil.
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Dissertations / Theses on the topic "Coherence time"

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De, Supinski Bronis R. "Logical time coherence maintenance." Full text, Acrobat Reader required, 1998. http://viva.lib.virginia.edu/etd/theses/supinski98.pdf.

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Abuhajar, Suhir. "Visualizing real time vasomotion in vivo using optical coherence tomography." Thesis, Lancaster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659170.

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As blood vessel imaging techniques facilitate the fundamental understanding in vascular performance diagnosis and biomedical research improvement, we aimed to visualize and understand the blood vessels dynamics under human skin and their underlying mechanisms in real time. In this study, a noninvasive imaging system was selected to provide an investigation of the real time oscillation of blood vessels in vivo, using Spectral Radar Optical Coherence Tomography (SROCT). This main goal was achieved by evaluating the precision and confidence in recorded data by using a phantom made of Intralipid (IL) to mimic the physical properties of the skin. Then, we successfully managed to visualize for the first time the vasomotion under human skin using MatLab Image Processing Toolbox. After that, we explored mathematically the cyclic variations of the vascular area obtained from the images for a cohort of six participants. The Fourier and wavelet transforms were applied to identify the characteristic frequencies related to the oscillations in vascular cross sectional area. Finally, we investigated dynamical aspects of vasomotion, in response to temperature change, by using a Meleor Thermoelectric Temperature Controller (MTTC) to produce local heating in conjunction with Spectral Radar Optical Coherence Tomography (SROCT).
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GUIDOBONI, Greta. "Spin Coherence Time studies for the storage ring EDM search." Doctoral thesis, Università degli studi di Ferrara, 2013. http://hdl.handle.net/11392/2388878.

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This thesis is part of the feasibility studies for a search for an Electric Dipole Moment (EDM) of charged particles in a storage ring. The evidence for a non-vanishing EDM at the sensitivity of present or planned experiments would clearly prove the existence of new CP violating meachanisms beyond the Standard Model. The proposed solution to measure the EDM of charged particles is the use of a storage ring where the polarized charged particle beam can be kept circulating while interacting with a radial electric field. Starting with a longitudinally polarized beam, the EDM signal would be detected as a polarization precession starting from the horizontal plane and rotating toward the vertical direction. A long horizontal polarization lifetime, called spin coherence time, is required since it represents the time available to observe the EDM signal. In order to have a sensitivity about 10−29 e·cm to the deuteron EDM, the spin coherence time should reach 1000 s while the measurement of a vertical polarization change should detect angles as small as micro-radians. The aim of this work is the analysis of the mechanisms which control the spin coherence time in a storage ring. The measurements presented here were made at the COSY (COoler SYnchrotron) ring located at the Forschungszentrum-J¨ulich GmbH (Germany). There are two set of measurements presented in this thesis: the first is a study of a spin resonance induced by a radio-frequency (rf) solenoid and the second shows the results from the first direct measurement of the horizontal polarization as a function of time. The first experiment sought to estimate the spin coherence time by measuring the width of a deuteron spin resonance induced by an rf-solenoid. Since the width of the resonance depends on the spin tune spread and thus on particle momentum distribution, each mechanism that can change the particle velocity in the beam could contribute to the spin tune spread. In particular, these mechanisms are betatron oscillations related to the beam emittance and synchrotron oscillations that are present only in a bunched beam. The experiment consisted in the measurement of the vertical polarization measurements with the rf-solenoid running at fixed frequency on and off resonance, for both uncooled and cooled bunched beam. In order to interpret the data, a simple “no-lattice” model was developed based on two rotation matrices for the spin precession about the vertical axis and the solenoid kick about the longitudinal axis; synchrotron oscillations were included as simple harmonic motion. The model demonstrated that the effect of synchrotron oscillations on the induced spin resonance were large enough to hide any dependence on emittance. The second experiment was the direct measurement of the horizontal polarization as a function of time. This task was accomplished through the development of a dedicated data acquisition system synchronized with the revolution frequency of the beam. By changing the horizontal beam emittance with a white noise electric field, the measurements gave the first experimental evidence of a dependence of the spin coherence time on the horizontal beam size. The dependence is due to the path lengthening introduced by betatron oscillations which forces the particles to go faster in order to respect the isochronous condition in a bunched beam. A possible method to correct for emittance effects is to use sextupole magnets. In fact the field varies as the square of the radius from the center and provides an adjustment to the particle orbit to remove the term driving the spin tune change. It has been demonstrated that for a particular value of sextupole strength the contribution from the horizontal emittance was canceled, reaching a spin coherence time of a hundred seconds.
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Anglada, Sánchez Martí. "Exploiting frame coherence in real-time rendering for energy-efficient GPUs." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669210.

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The computation capabilities of mobile GPUs have greatly evolved in the last generations, allowing real-time rendering of realistic scenes. However, the desire for processing complex environments clashes with the battery-operated nature of smartphones, for which users expect long operating times per charge and a low-enough temperature to comfortably hold them. Consequently, improving the energy-efficiency of mobile GPUs is paramount to fulfill both performance and low-power goals. The work of the processors from within the GPU and their accesses to off-chip memory are the main sources of energy consumption in graphics workloads. Yet most of this energy is spent in redundant computations, as the frame rate required to produce animations results in a sequence of extremely similar images. The goal of this thesis is to improve the energy-efficiency of mobile GPUs by designing micro-architectural mechanisms that leverage frame coherence in order to reduce the redundant computations and memory accesses inherent in graphics applications. First, we focus on reducing redundant color computations. Mobile GPUs typically employ an architecture called Tile-Based Rendering, in which the screen is divided into tiles that are independently rendered in on-chip buffers. It is common that more than 80% of the tiles produce exactly the same output between consecutive frames. We propose Rendering Elimination (RE), a mechanism that accurately determines such occurrences by computing and storing signatures of the inputs of all the tiles in a frame. If the signatures of a tile across consecutive frames are the same, the colors computed in the preceding frame are reused, saving all computations and memory accesses associated to the rendering of the tile. We show that RE vastly outperforms related schemes found in the literature, achieving a reduction of energy consumption of 37% and execution time of 33% with minimal overheads. Next, we focus on reducing redundant computations of fragments that will eventually not be visible. In real-time rendering, objects are processed in the order they are submitted to the GPU, which usually causes that the results of previously-computed objects are overwritten by new objects that turn occlude them. Consequently, whether or not a particular object will be occluded is not known until the entire scene has been processed. Based on the fact that visibility tends to remain constant across consecutive frames, we propose Early Visibility Resolution (EVR), a mechanism that predicts visibility based on information obtained in the preceding frame. EVR first computes and stores the depth of the farthest visible point after rendering each tile. Whenever a tile is rendered in the following frame, primitives that are farther from the observer than the stored depth are predicted to be occluded, and processed after the ones predicted to be visible. Additionally, this visibility prediction scheme is used to improve Rendering Elimination’s equal tile detection capabilities by not adding primitives predicted to be occluded in the signature. With minor hardware costs, EVR is shown to provide a reduction of energy consumption of 43% and execution time of 39%. Finally, we focus on reducing computations in tiles with low spatial frequencies. GPUs produce pixel colors by sampling triangles once per pixel and performing computations on each sampling location. However, most screen regions do not include sufficient detail to require high sampling rates, leading to a significant amount of energy wasted computing the same color for neighboring pixels. Given that spatial frequencies are maintained across frames, we propose Dynamic Sampling Rate, a mechanism that analyzes the spatial frequencies of tiles and determines the best sampling rate for them, which is applied in the following frame. Results show that Dynamic Sampling Rate significantly reduces processor activity, yielding energy savings of 40% and execution time reductions of 35%.
La capacitat de càlcul de les GPU mòbils ha augmentat en gran mesura en les darreres generacions, permetent el renderitzat de paisatges complexos en temps real. Nogensmenys, el desig de processar escenes cada vegada més realistes xoca amb el fet que aquests dispositius funcionen amb bateries, i els usuaris n’esperen llargues durades i una temperatura prou baixa com per a ser agafats còmodament. En conseqüència, millorar l’eficiència energètica de les GPU mòbils és essencial per a aconseguir els objectius de rendiment i baix consum. Els processadors de la GPU i els seus accessos a memòria són els principals consumidors d’energia en càrregues gràfiques, però molt d’aquest consum és malbaratat en càlculs redundants, ja que les animacions produïdes s¿aconsegueixen renderitzant una seqüència d’imatges molt similars. L’objectiu d’aquesta tesi és millorar l’eficiència energètica de les GPU mòbils mitjançant el disseny de mecanismes microarquitectònics que aprofitin la coherència entre imatges per a reduir els càlculs i accessos redundants inherents a les aplicacions gràfiques. Primerament, ens centrem en reduir càlculs redundants de colors. A les GPU mòbils, sovint s'empra una arquitectura anomenada Tile-Based Rendering, en què la pantalla es divideix en regions que es processen independentment dins del xip. És habitual que més del 80% de les regions de pantalla produeixin els mateixos colors entre imatges consecutives. Proposem Rendering Elimination (RE), un mecanisme que determina acuradament aquests casos computant una signatura de les entrades de totes les regions. Si les signatures de dues imatges són iguals, es reutilitzen els colors calculats a la imatge anterior, el que estalvia tots els càlculs i accessos a memòria de la regió. RE supera àmpliament propostes relacionades de la literatura, aconseguint una reducció del consum energètic del 37% i del temps d’execució del 33%. Seguidament, ens centrem en reduir càlculs redundants en fragments que eventualment no seran visibles. En aplicacions gràfiques, els objectes es processen en l’ordre en què son enviats a la GPU, el que sovint causa que resultats ja processats siguin sobreescrits per nous objectes que els oclouen. Per tant, no se sap si un objecte serà visible o no fins que tota l’escena ha estat processada. Fonamentats en el fet que la visibilitat tendeix a ser constant entre imatges, proposem Early Visibility Resolution (EVR), un mecanisme que prediu la visibilitat basat en informació obtinguda a la imatge anterior. EVR computa i emmagatzema la profunditat del punt visible més llunyà després de processar cada regió de pantalla. Quan es processa una regió a la imatge següent, es prediu que les primitives més llunyanes a el punt guardat seran ocloses i es processen després de les que es prediuen que seran visibles. Addicionalment, aquest esquema de predicció s’empra en millorar la detecció de regions redundants de RE al no afegir les primitives que es prediu que seran ocloses a les signatures. Amb un cost de maquinari mínim, EVR aconsegueix una millora del consum energètic del 43% i del temps d’execució del 39%. Finalment, ens centrem a reduir càlculs en regions de pantalla amb poca freqüència espacial. Les GPU actuals produeixen colors mostrejant els triangles una vegada per cada píxel i fent càlculs a cada localització mostrejada. Però la majoria de regions no tenen suficient detall per a necessitar altes freqüències de mostreig, el que implica un malbaratament d’energia en el càlcul del mateix color en píxels adjacents. Com les freqüències tendeixen a mantenir-se en el temps, proposem Dynamic Sampling Rate (DSR)¸ un mecanisme que analitza les freqüències de les regions una vegada han estat renderitzades i en determina la menor freqüència de mostreig a la que es poden processar, que s’aplica a la següent imatge...
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Twengström, Mikael. "Time-reversal symmetry breaking and mixed coherence lengths in multicomponent superconductors." Thesis, KTH, Fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-138163.

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Wojcik, Aleksander Karol. "Signal statistics of phase dependent optical time domain reflectometry." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4873.

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The statistics of the phase dependent optical time-domain reflectometer have been analyzed. The optical fiber is modeled by the use of a discrete set of reflectors positioned randomly along the fiber. The statistics of the reflected light from a traveling pulse are derived. The statistics of the signal are used to calculate the characteristics of shot noise in the photodetector, and the probability that noise of certain intensity will occur. An estimation of the backscattered power is made by calculating the fraction of the backscattered power that is captured in a guiding mode. Upper power limits are calculated by considering nonlinear optical effects. An estimation of noise from thermally excited sound waves, amplified by Brillouin scattering, is derived. This noise considers the parameters of a photodetector, giving a model for the noise in the measurable photocurrent. Two models are used to describe the fading probability of the signal. The first model, based on the Fabry-Perot interferometer with a random phase perturbation in the middle, is used to calculate the probability that the whole signal vanishes for any value of phase perturbation. The second model, by calculating the correlation between two signals, one perturbed and one unperturbed, predicts the fading of the signal of interest. The present work gives the theoretical basis for the phase dependant Optical Time Domain Reflectometry, allowing its optimization and setting the fundamental limitations to the performance of the system.
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Panagos, Adam G., and Kurt Kosbar. "MIMO CHANNEL TIME VARIATION AS A FUNCTION OF MOBILE USER VELOCITY." International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/605780.

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International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California
The analysis of multiple-input multiple-output (MIMO) communication systems often assumes a static, or quasi-static, environment. Platform motion and changes in the environment makes this an unreasonable assumption for many telemetry applications. This paper uses computer simulations to characterize the time variation of MIMO channel parameters when there is relative motion between the transmitter and receiver. These simulation results yield explicit time intervals over which a MIMO channel can be considered static for a given relative velocity and propagation environment. These results can be used to predict the practical limitations of proposed MIMO system algorithms.
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Chen, Jiajian. "Non-photorealistic rendering with coherence for augmented reality." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45749.

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A seamless blending of the real and virtual worlds is key to increased immersion and improved user experiences for augmented reality (AR). Photorealistic and non-photorealistic rendering (NPR) are two ways to achieve this goal. Non-photorealistic rendering creates an abstract and stylized version of both the real and virtual world, making them indistinguishable. This could be particularly useful in some applications (e.g., AR/VR aided machine repair, or for virtual medical surgery) or for certain AR games with artistic stylization. Achieving temporal coherence is a key challenge for all NPR algorithms. Rendered results are temporally coherent when each frame smoothly and seamlessly transitions to the next one without visual flickering or artifacts that distract the eye from perceived smoothness. NPR algorithms with coherence are interesting in both general computer graphics and AR/VR areas. Rendering stylized AR without coherence processing causes the final results to be visually distracting. While various NPR algorithms with coherence support have been proposed in general graphics community for video processing, many of these algorithms require thorough analysis of all frames of the input video and cannot be directly applied to real-time AR applications. We have investigated existing NPR algorithms with coherence in both general graphics and AR/VR areas. These algorithms are divided into two categories: Model Space and Image Space. We present several NPR algorithms with coherence for AR: a watercolor inspired NPR algorithm, a painterly rendering algorithm, and NPR algorithms in the model space that can support several styling effects.
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Ansari, Zunaira. "Whole field, real time photorefractive holography for imaging through turbid media using sources of diverse spatial and temporal coherence." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289853.

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Freiberger, Manuel. "A time domain optical coherence tomograph for laboratory investigations on phantoms and human skin." Thesis, Linköping University, Department of Biomedical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-3852.

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Optical coherence tomography is an imaging modality with an outstanding resolution. During the project, a time domain OCT system based on a Michelson fibre interferometer was implemented and put into operation. A super-luminescent diode with a centre wavelength of 1295nm and a bandwidth of 45nm was selected as light source and a linear variable delay line as reference. Basic tests were made on phantoms constructed of filter foils and on gel-like agar slices with optical properties similar to human tissue. It was shown that the achievable resolution was at least 36um and can be increased. The system can easily be enhanced to create two-dimensional images.


Optische Kohärenztomographie ist ein bildgebendes Verfahren mit einer hervorragenden räumlichen Auflösung. Im Laufe des Projekts wurde ein OCT-System basierend auf einem faseroptischen Michelson-Interferometer implementiert und in Betrieb genommen. Als Lichtquelle wurde eine Superlumineszenzdiode mit einer Mittenwellenlänge von 1295nm und einer Bandbreite von 45nm gewählt. Eine variable optische Verzögerungsleitung diente als Referenz. Erste Messungen an Filterfolien und gelähnlichen Agarphantomen, die die optischen Eigenschaften von menschlichem Gewebe nachbildeten, lieferten eine räumliche Auflösung von mindestens 36um. Durch die modulare Bauweise ist das System leicht für zweidimensionale Aufnahmen erweiterbar.

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Books on the topic "Coherence time"

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Yuri, Kivshar, Rosanov Nikolay N, SPIE (Society), and Natsyi︠a︡nalʹnai︠a︡ akadėmii︠a︡ navuk Belarusi, eds. ICONO 2007: Nonlinear space-time dynamics : 28 May-1 June 2007, Minsk, Belarus. Bellingham, Wash: SPIE, 2006.

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Craig, William Lane. God, time, and eternity: The coherence of theism II : eternity. Dordrecht: Kluwer Academic Publishers, 2001.

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God, time, and eternity: The coherence of theism II : eternity. Dordrecht: Kluwer Academic, 2001.

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ICONO 2005 (2005 St. Petersburg, Russia). ICONO 2005: Nonlinear space-time dynamics : 11-15 May 2005, St. Petersburg, Russia. Edited by Rosanov Nikolay N, Trillo Stefano 1957-, Rossiĭskai︠a︡ akademii︠a︡ nauk, Russian Ministry of Education and Science., and Society of Photo-optical Instrumentation Engineers. Bellingham, Wash: SPIE, 2006.

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Clifford, Carter G., ed. Coherence and time delay estimation: An applied tutorial for research, development, test, and evaluation engineers. Piscataway, NJ: IEEE Press, 1993.

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A, Nowak Michael, and United States. National Aeronautics and Space Administration., eds. X-ray variability coherence: How to compute it, what it means, and how it constrains models of GX 339-4 and Cygnus X-1. [Washington, DC: National Aeronautics and Space Administration, 1997.

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A, Nowak Michael, and United States. National Aeronautics and Space Administration., eds. X-ray variability coherence: How to compute it, what it means, and how it constrains models of GX 339-4 and Cygnus X-1. [Washington, DC: National Aeronautics and Space Administration, 1997.

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A, Nowak Michael, and United States. National Aeronautics and Space Administration., eds. X-ray variability coherence: How to compute it, what it means, and how it constrains models of GX 339-4 and Cygnus X-1. [Washington, DC: National Aeronautics and Space Administration, 1997.

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Maiti, Raju. Modelling and coherent forecasting of zero-inflated time series count data. Ahmedabad: Indian Institute of Management, 2013.

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Domen, Verber, and Halang Wolfgang A. 1951-, eds. Distributed embedded control systems: Improving dependability with coherent design. London: Springer, 2008.

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Book chapters on the topic "Coherence time"

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Weik, Martin H. "time coherence." In Computer Science and Communications Dictionary, 1786. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_19613.

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Ramírez, David, Ignacio Santamaría, and Louis Scharf. "Detection of Spatially Correlated Time Series." In Coherence, 235–57. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-13331-2_8.

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Naik, Dinesh N., Takahiro Ezawa, Yoko Miyamoto, and Mitsuo Takeda. "Real-time Coherence Holography." In Fringe 2009, 1–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03051-2_4.

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Frøyland, Jan. "Time Series Analysis." In Introduction to Chaos and Coherence, 107–18. New York: Routledge, 2022. http://dx.doi.org/10.1201/9780203750162-11.

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Harms, Fabrice, Anne Latrive, and A. Claude Boccara. "Time Domain Full Field Optical Coherence Tomography Microscopy." In Optical Coherence Tomography, 791–812. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-06419-2_26.

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Vergeiner, Philip C., Dominik Wallner, and Lars Bülow. "Language change in real-time." In The Coherence of Linguistic Communities, 281–300. New York: Routledge, 2022. http://dx.doi.org/10.4324/9781003134558-21.

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Horwitz, Lawrence P. "Experimental Consequences of Coherence in Time." In Fundamental Theories of Physics, 97–111. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-7261-7_6.

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Gambini, Rodolfo, Rafael A. Porto, and Jorge Pullin. "Fundamental Loss of Quantum Coherence from Quantum Gravity." In The Arrows of Time, 43–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-23259-6_3.

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Fu, Yaotian. "Response Time in High-Frequency Quantum Transport." In Quantum Coherence in Mesoscopic Systems, 333–38. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4899-3698-1_22.

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Branning, D., and A. L. Migdall. "Observation of time-dependent inhibited spontaneous emission." In Coherence and Quantum Optics VIII, 507–8. Boston, MA: Springer US, 2003. http://dx.doi.org/10.1007/978-1-4419-8907-9_141.

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Conference papers on the topic "Coherence time"

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Zeng, Yifeng, Shiqi Xu, William C. Chapman, Shuying Li, Zahra Alipour, Heba Abdelal, Deyali Chatterjee, Matthew Mutch, and Quing Zhu. "Real-time colorectal cancer diagnosis using PR-OCT with deep learning." In Optical Coherence Tomography. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/oct.2020.ow2e.5.

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Asghari, Hossein, and Max Hushahn. "Multi-probe photonic time-stretch optical coherence tomography." In Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVI, edited by Joseph A. Izatt and James G. Fujimoto. SPIE, 2022. http://dx.doi.org/10.1117/12.2608916.

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Cernat, Ramona C., Adrian Bradu, Sylvain Rivet, and Adrian Podoleanu. "Time efficient Gabor fused master slave optical coherence tomography." In Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXII, edited by Joseph A. Izatt, James G. Fujimoto, and Valery V. Tuchin. SPIE, 2018. http://dx.doi.org/10.1117/12.2292058.

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Wei, Xiang, Tristan T. Hormel, Yukun Guo, and Yali Jia. "Self-tracking real-time wide-field OCT angiography (Conference Presentation)." In Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXIV, edited by Joseph A. Izatt and James G. Fujimoto. SPIE, 2020. http://dx.doi.org/10.1117/12.2542865.

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Li, Jianhua, Liang Shi, Qingan Li, Chun Jason Xue, and Yinlong Xu. "TEACA: Thread ProgrEss Aware Coherence Adaption for hybrid coherence protocols." In 2012 IEEE 10th Symposium on Embedded Systems for Real-time Multimedia (ESTIMedia). IEEE, 2012. http://dx.doi.org/10.1109/estimedia.2012.6507024.

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STODOLSKY, L. "COHERENCE AND THE CLOCK." In Proceedings of the International Colloquium on the Science of Time. WORLD SCIENTIFIC, 2006. http://dx.doi.org/10.1142/9789812774392_0008.

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Jeong, Hyeonseog, Hyung-Jin Kim, Min Gyu Hyeon, Youngwoon Choi, and Beop-Min Kim. "Shadow rendering for improved volumetric visualization in real time 4D-OCT." In Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXIII, edited by Joseph A. Izatt and James G. Fujimoto. SPIE, 2019. http://dx.doi.org/10.1117/12.2510923.

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Moiseev, Alexander A., Grigory V. Gelikonov, Sergey Y. Ksenofontov, Valentin M. Gelikonov, Lev A. Matveev, Vladimir Y. Zaitsev, Alexander L. Matveev, Marina A. Sirotkina, Natalia D. Gladkova, and I. Alex Vitkin. "Real time OCT-based angiography device with hand-held probe (Conference Presentation)." In Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXI, edited by Joseph A. Izatt, James G. Fujimoto, and Valery V. Tuchin. SPIE, 2017. http://dx.doi.org/10.1117/12.2254962.

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García-Ramírez¹, Fernando E., Sylwester Bargiel¹, Olivier Gaiffe¹, Quentin A. A. Tanguy¹, Przemyslaw Struk, Jean-Marc Cote¹, Nicolas Passilly¹, Philippe Lutz¹, Christophe Gorecki¹, and Huikai Xie³. "Characterization of an integrated MOEMS scanning probe towards real-time Lissajous-based SS-OCT imaging for endoscopic applications." In Optical Coherence Tomography. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/oct.2020.otu4e.5.

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Abouraddy, Ayman F. "Space-Time Wave Packets: Recent Developments." In Conference on Coherence and Quantum Optics. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/cqo.2019.th1a.1.

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Reports on the topic "Coherence time"

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Pan, Wei, John Reno, and Julien Tranchida. Enhance coherence time in intensely driven quantum systems. Office of Scientific and Technical Information (OSTI), September 2020. http://dx.doi.org/10.2172/1670245.

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Schoelkopf, R. J., K. W. Lehnert, K. Bladh, L. F. Spietz, and D. I. Schuster. Measurement of the Excited-State Lifetime and Coherence Time of a Microelectronic Circuit. Fort Belvoir, VA: Defense Technical Information Center, August 2002. http://dx.doi.org/10.21236/ada414293.

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Emmerson, Stephen. Modulations through time. Norges Musikkhøgskole, August 2018. http://dx.doi.org/10.22501/nmh-ar.530427.

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This article explores the rationale behind a performance given by the authors at the Unfolding the Process symposium held in Oslo in November 2015. For this occasion, the authors devised a new version of Bach’s Goldberg Variations that builds upon Emmerson’s arrangement of the work for two pianos in 2012. A shortened version of the work (c.30 minutes) was designed that aimed nonetheless to maintain the original work’s sense of structural balance and coherence. This version involved the transposition of a number of variations into different keys to explore the possibility of adding a satisfying tonal structure to our experience of the work, in a context where both performers see potential communicative value in 'playing with' dimensions of original masterworks with a view to giving fresh perspective to the listener experience. The article is written from the alternating perspectives of the authors; one of which is primarily concerned with the rationale and process of devising the arrangement while the other reflects upon the performative aspects and implications arising from it.
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London, Jonathan. Outlier Vietnam and the Problem of Embeddedness: Contributions to the Political Economy of Learning. Research on Improving Systems of Education (RISE), February 2021. http://dx.doi.org/10.35489/bsg-rise-wp_2021/062.

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Recent literature on the political economy of education highlights the role of political settlements, political commitments, and features of public governance in shaping education systems’ development and performance around learning. Vietnam’s experiences provide fertile ground for the critique and further development of this literature including, especially, its efforts to understand how features of accountability relations shape education systems’ performance across time and place. Globally, Vietnam is a contemporary outlier in education, having achieved rapid gains in enrolment and strong learning outcomes at relatively low levels of income. This paper proposes that beyond such felicitous conditions as economic growth and social historical and cultural elements that valorize education, Vietnam’s distinctive combination of Leninist political commitments to education and high levels of societal engagement in the education system often works to enhance accountability within the system in ways that contribute to the system’s coherence around learning; reflecting the sense and reality that Vietnam is a country in which education is a first national priority. Importantly, these alleged elements exist alongside other features that significantly undermine the system’s coherence and performance around learning. These include, among others, the system’s incoherent patterns of decentralization, the commercialization and commodification of schooling and learning, and corresponding patterns of systemic inequality. Taken together, these features of education in Vietnam underscore how the coherence of accountability relations that shape learning outcomes are contingent on the manner in which national and local systems are embedded within their broader social environments while also raising intriguing ideas for efforts to understand the conditions under which education systems’ performance with respect to learning can be promoted, supported, and sustained.
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Miocinovic, P., R. C. Field, P. W. Gorham, E. Guillian, R. Milincic, D. Saltzberg, D. Walz, and D. Williams. Time-Domain Measurement of Broadband Coherent Cherenkov Radiation. Office of Scientific and Technical Information (OSTI), March 2006. http://dx.doi.org/10.2172/877430.

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Richardson, J. David, and Chi Zhang. Revealing Comparative Advantage: Chaotic or Coherent Patterns Across Time and Sector and U.S. Trading Partner? Cambridge, MA: National Bureau of Economic Research, July 1999. http://dx.doi.org/10.3386/w7212.

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Talman, Richard. Simulation and Optimization of the Spin Coherent Time for the Proton Electric Dipole Moment Measurement. Office of Scientific and Technical Information (OSTI), April 2012. http://dx.doi.org/10.2172/1060704.

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Long, Owen R. Impact of Tag-Side Interference on Time-Dependent CP Asymmetry Measurements Using Coherent B0-B0bar Pairs. Office of Scientific and Technical Information (OSTI), March 2003. http://dx.doi.org/10.2172/812971.

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London, Jonathan D. Adoption, Adaption, and the Iterative Challenges of Scaling up in Vietnam: Policy Entrepreneurship and System Coherence in a Major Pedagogical Reform. Research on Improving Systems of Education (RISE), March 2023. http://dx.doi.org/10.35489/bsg-rise-misc_2023/11.

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Đặng Tự Ân played a pivotal role in the genesis, adoption, and diffusion of pedagogical and curricular reforms that are transforming teaching and learning in the Socialist Republic of Vietnam. His is a fascinating story of a career that began with the paralyzing disappointment of being assigned to study in a seemingly lowly teacher training college only to culminate, decades later, in his central role in the research, design, piloting, and scaling up of a reform that, despite numerous difficulties, would shape the most far-reaching and progressive curricular reforms in Vietnam’s long educational history. This essay uses the case of VNEN, a pedagogical and curricular reform adapted to Vietnam from the Colombian Escuela Nueva (EN) model, to advance our understanding of the challenges policy entrepreneurs and networks of policy stakeholders can encounter in efforts to institute pathbreaking reforms and of the formidable challenges they can encounter in bringing such reforms to scale. In contemporary research on the political economy of education and learning, the notion of an education system’s coherence for learning refers to the extent to which an education system develops relations of accountability that support improved learning outcomes across a range of relationships that define an education system and an array of policy design elements that education policies contain (Pritchett 2015, Kaffenberger and Spivack 2022). In the development literature, the notion of iterative adaptation speaks to a process wherein the performance of policies can improve rapidly through experimentation rather than mechanical transplantation of “best practices” (Andrews et al. 2013, Le 2018). From the standpoint of research on education systems and major reform efforts aimed at enhancing learning, the case of VNEN represents a particularly interesting instance of the innovation of pedagogical and curricular reforms that were, at their most successful moments, deeply coherent for learning, but which encountered problems at scale owing to a range of factors highlighted in this analysis. More broadly and however problematic at times, Vietnam’s VNEN experience contributed to the broad uptake and diffusion of new curricula and teaching practices. This raises questions about what we can learn from VNEN, including its successes and problems, that may have value for promoting continued improvement in Education systems performance around learning in Vietnam and other settings.
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Wallgren, Anders, and Britt Wallgren. Toward an Integrated Statistical System Based on Registers. Inter-American Development Bank, April 2021. http://dx.doi.org/10.18235/0003204.

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This note describes how Latin American and Caribbean countries can join a revolution in statistical systems, moving from data collection based on geographic frames to one based on administrative registers, and the advantages of making this change. Northern European countries have already shifted from a traditional area frame-based statistical system to a register-based system, in which all surveys are based on statistical registers. Among the key advantages of the shift are: i) lower production costs; ii) potential for higher levels of geographic disaggregation and greater frequency; and iii) reduce the burden on informants by following the maxim of “ask once, use many times”. Evidence from Colombia, Ecuador, Mexico, and Peru points to the viability of this transition in the region. However, to take better advantage of the new strategy, countries should invest to improve the quality and coverage of their administrative systems and should create an integrated register system, allowing for efficient data use, and ensuring consistency and coherence across statistical registries.
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