Journal articles: 'Sum of coherence'

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Da´vila, Jose´ B., Muhammad R. Hajj, Richard W. Miksad, and Edward J. Powers. "Spatial Coherence in the Wake of a Flat Plate." Applied Mechanics Reviews 50, no. 11S (November 1, 1997): S36—S38. http://dx.doi.org/10.1115/1.3101846.

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Spatial coherence of the streamwise velocity fluctuation was measured in the wake of a flat plate in a wind tunnel. The measurements were made in the context of determining the role of wavenumber resonance in quadratic interactions among resonant frequency modes. Frequency domain results show that sum-interaction modes targeted by coupled mode pairs are spatially coherent. This suggests that spatial coherence measurements can be combined with bispectral measurements to determine mode energy transit and direction.

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Wilson, Hugh R., and Jeounghoon Kim. "A model for motion coherence and transparency." Visual Neuroscience 11, no. 6 (November 1994): 1205–20. http://dx.doi.org/10.1017/s0952523800007008.

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AbstractA recent model for two-dimensional motion processing in MT has demonstrated that perceived direction can be accurately predicted by combining Fourier and non-Fourier component motion signals using a vector sum computation. The vector sum direction is computed by a neural network that weights Fourier and non-Fourier components by the cosine of the component direction relative to that of each pattern unit, after which competitive inhibition extracts the signals of the most active units. It is shown here that a minor modification of the connectivity in this network suffices to predict transitions from motion coherence to transparency under a wide range of circumstances. It is only necessary that the cosine weighting function and competitive inhibition be limited to directions within ± 120 deg of each pattern unit's preferred direction. This network responds by signaling one pattern direction for coherent motion but two distinct directions for transparent motion. Based on this, neural networks with properties of MT and MST neurons can automatically signal motion coherence or transparency. In addition, the model accurately predicts motion repulsion under transparency conditions.

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Shen, Che-Chou, and Pei-Ying Hsieh. "Two-Dimensional Spatial Coherence for Ultrasonic DMAS Beamforming in Multi-Angle Plane-Wave Imaging." Applied Sciences 9, no. 19 (September 23, 2019): 3973. http://dx.doi.org/10.3390/app9193973.

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Ultrasonic multi-angle plane-wave (PW) coherent compounding relies on delay-and-sum (DAS) beamforming of two-dimensional (2D) echo matrix in both the dimensions PW transmit angle and receiving channel to construct each image pixel. Due to the characteristics of DAS beamforming, PW coherent compounding may suffer from high image clutter when the number of transmit angles is kept low for ultrafast image acquisition. Delay-multiply-and-sum (DMAS) beamforming exploits the spatial coherence of the receiving aperture to suppress clutter interference. Previous attempts to introduce DMAS beamforming into multi-angle PW imaging has been reported but only in either dimension of the 2D echo matrix. In this study, a novel DMAS operation is proposed to extract the 2D spatial coherence of echo matrix for further improvement of image quality. The proposed 2D-DMAS method relies on a flexibly tunable p value to manipulate the signal coherence in the beamforming output. For p = 2.0 as an example, simulation results indicate that 2D-DMAS outperforms other one-dimensional DMAS methods by at least 9.3 dB in terms of ghost-artifact suppression. Experimental results also show that 2D-DMAS provides the highest improvement in lateral resolution by 32% and in image contrast by 15.6 dB relative to conventional 2D-DAS beamforming. Nonetheless, since 2D-DMAS emphasizes signal coherence more than its one-dimensional DMAS counterparts, it suffers from the most elevated speckle variation and the granular pattern in the tissue background.

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Qi, Jie, Fangyu Li, and Kurt Marfurt. "Multiazimuth coherence." GEOPHYSICS 82, no. 6 (November 1, 2017): O83—O89. http://dx.doi.org/10.1190/geo2017-0196.1.

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Since its introduction two decades ago, coherence has been widely used to map structural and stratigraphic discontinuities such as faults, cracks, karst collapse features, channels, stratigraphic edges, and unconformities. With the intent to map azimuthal variations of horizontal stress as well as to improve the signal-to-noise ratio of unconventional resource plays, wide-/full-azimuth seismic data acquisition has become common. Migrating seismic traces into different azimuthal bins costs no more than migrating them into one bin. If the velocity anisotropy is not taken into account by the migration algorithm, subtle discontinuities and some major faults may exhibit lateral shifts, resulting in a smeared image after stacking. Based on these two issues, we evaluate a new way to compute the coherence for azimuthally limited data volumes. Like multispectral coherence, we modify the covariance matrix to be the sum of the covariance matrices, each of which belongs to an azimuthally limited volume, and then we use the summed covariance matrix to compute the coherent energy. We validate the effectiveness of our multiazimuth coherence by applying it to two seismic surveys acquired over the Fort Worth Basin, Texas. Not surprisingly, multiazimuth coherence exhibits less incoherent noise than coherence computed from azimuthally limited amplitude volumes. If the data have been migrated using an azimuthally variable velocity, multiazimuth coherence exhibits higher lateral resolution than that computed from the stacked data. In contrast, if the data have not been migrated using an appropriate azimuthally variable velocity model, the misalignment of each image results in a blurring of the multiazimuth coherence and the coherence computed from the stacked data. This suggests that our method may serve as a future tool for azimuthal velocity analysis.

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Dai, Meifeng, Jiaojiao He, Huiling Wu, and Xianbin Wu. "Spectra analysis and network coherence for weighted folded hypercube." International Journal of Modern Physics B 33, no. 11 (April 30, 2019): 1950094. http://dx.doi.org/10.1142/s0217979219500942.

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Weighted folded hypercube is an charming variance of the famous hypercube and is superior to the weighted hypercube in many criteria. We mainly study the scaling of network coherence for the weighted folded hypercube that is controlled by a weight factor. Network coherence quantifies the steady-state variance of these fluctuations, and it can be regarded as a measure of robustness of the consensus process to the additive noise. If networks with small steady-state variance have better network coherence, it can be regarded as more robust to noise than networks with low coherence. We firstly calculate the spectra of weighted folded hypercube and obtain the leading terms of network coherence that are quantified as the sum and square sum of reciprocals of all nonzero Laplacian eigenvalues. Finally, the results show that network coherence depends on iterations and weight factor. Meanwhile, with larger order, the scatings of the first- and second-order network coherence of weighted folded hypercube decrease with the increasing of weight factor.

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Dai, Meifeng, Tingting Ju, Yongbo Hou, Jianwei Chang, Yu Sun, and Weiyi Su. "Coherence analysis of a family of weighted star-composed networks." International Journal of Modern Physics B 33, no. 23 (September 20, 2019): 1950264. http://dx.doi.org/10.1142/s0217979219502643.

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Recently, the study of many kinds of weighted networks has received the attention of researchers in the scientific community. In this paper, first, a class of weighted star-composed networks with a weight factor is introduced. We focus on the network consistency in linear dynamical system for a class of weighted star-composed networks. The network consistency can be characterized as network coherence by using the sum of reciprocals of all nonzero Laplacian eigenvalues, which can be obtained by using the relationship of Laplacian eigenvalues at two successive generations. Remarkably, the Laplacian matrix of the class of weighted star-composed networks can be represented by the Kronecker product, then the properties of the Kronecker product can be used to obtain conveniently the corresponding characteristic roots. In the process of finding the sum of reciprocals of all nonzero Laplacian eigenvalues, the key step is to obtain the relationship of Laplacian eigenvalues at two successive generations. Finally, we obtain the main results of the first- and second-order network coherences. The obtained results show that if the weight factor is 1 then the obtained results in this paper coincide with the previous results on binary networks, otherwise the scalings of the first-order network coherence are related to the node number of attaching copy graph, the weight factor and generation number. Surprisingly, the scalings of the first-order network coherence are independent of the node number of initial graph. Consequently, it will open up new perspectives for future research.

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He, Jiaojiao, Meifeng Dai, Yue Zong, Jiahui Zou, Yu Sun, and Weiyi Su. "Coherence analysis of a class of weighted tree-like polymer networks." Modern Physics Letters B 32, no. 05 (February 20, 2018): 1850064. http://dx.doi.org/10.1142/s0217984918500641.

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Complex networks have elicited considerable attention from scientific communities. This paper investigates consensus dynamics in a linear dynamical system with additive stochastic disturbances, which is characterized as network coherence by the Laplacian spectrum. Firstly, we introduce a class of weighted tree-like polymer networks with the weight factor. Then, we deduce the recursive relationship of the eigenvalues of Laplacian matrix at two successive generations. Finally, we calculate the first- and second-order network coherence quantifying as the sum and square sum of reciprocals of all nonzero Laplacian eigenvalues. The obtained results show that the scalings of first-order coherence with network size obey four laws along with the range of the weight factor and the scalings of second-order coherence with network size obey five laws along with the range of the weight factor.

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Chopra, Satinder, and Kurt J. Marfurt. "Multispectral, multiazimuth, and multioffset coherence attribute applications." Interpretation 7, no. 2 (May 1, 2019): SC21—SC32. http://dx.doi.org/10.1190/int-2018-0090.1.

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The coherence attribute computation is typically carried out as a poststack application on 3D prestack migrated seismic data volumes. However, since its inception, interpreters have applied coherence to band-pass-filtered data, azimuthally limited stacks, and offset-limited stacks to enhance discontinuities seen at specific frequencies, azimuths, and offsets. The limitation of this approach is the multiplicity of coherence volumes. Of the various coherence algorithms that have evolved over the past 25 years, the energy ratio coherence computation stands apart from the others, being more sensitive to the seismic waveform changes rather than changes in their amplitude. The energy ratio algorithm is based on the crosscorrelation of five or more adjacent traces to form a symmetric covariance matrix that can then be decomposed into eigenvalues and eigenvectors. The first eigenvector represents a vertically variable, laterally consistent pattern that best represents the data in the analysis window. The first eigenvalue represents the energy of the data represented by this pattern. Coherence is then defined as the ratio of the energy represented by the first eigenvalue to the sum of the energy of the original data. An early generalization of this algorithm was to compute the sum of two covariance matrices, one from the original data and the other from the 90° phase rotated data, thereby eliminating artifacts about low-amplitude zero crossings. More recently, this concept has been further generalized by computing a sum of covariance matrices of traces represented by multiple spectral components, by their azimuthally limited stacks, and by their offset-limited stacks. These more recently developed algorithms capture many of the benefits of discontinuities seen at specific frequencies, azimuths, and offsets, but they present the interpreter with a single volume. We compare the results of multispectral, multiazimuth, and multioffset coherence volumes with the traditional coherence computation, and we find that these newer coherence computation procedures produce superior results.

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Kibria, Salehin, Md Samsuzzaman, Md Tarikul Islam, Md Zulfiker Mahmud, Norbahiah Misran, and Mohammad Tariqul Islam. "Breast Phantom Imaging Using Iteratively Corrected Coherence Factor Delay and Sum." IEEE Access 7 (2019): 40822–32. http://dx.doi.org/10.1109/access.2019.2906566.

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Dai, Meifeng, Yue Zong, Jiaojiao He, Tingting Ju, Yu Sun, and Weiyi Su. "Consensus dynamics on a family of weighted recursive trees." Modern Physics Letters B 33, no. 02 (January 20, 2019): 1950003. http://dx.doi.org/10.1142/s0217984919500039.

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The consensus dynamics with additive stochastic disturbances are characterized by the network coherence, which is the robustness of consensus algorithms when the nodes are subject to external perturbations. In this paper, the research goal is to obtain the first- and second-order network coherence quantifying as the sum and square sum of reciprocals of all nonzero Laplacian eigenvalues. One innovation point of this paper is the structure of a family of the weighted recursive trees with weight factor. We mainly obtain the exact expressions and scalings of network coherence on the family of weighted recursive trees. The scalings of first-order network coherence with network size obey three laws along with the range of the weight factor, while the scalings of second-order network coherence obey four laws along with the range of the weight factor. In addition, the scalings of first- and second-order network coherence on our studied networks are smaller than those performed on other studied networks when [Formula: see text]. The obtained results indicate that the efficiency of network coherence on the weighted network has close relation to the weight distribution, and we can design a better weight distribution to make the coherence of network more efficient.

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Nedeljkovic, Adam. "One example of formal coherence." Theoria, Beograd 61, no. 3 (2018): 39–53. http://dx.doi.org/10.2298/theo1803039n.

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The aim of this paper is to present one case of probabilistic formalization of our intuitive notion of coherence. To that end, we will have to provide answers for the questions, what are all relevant relations between beliefs, as far as coherence is concerned, and of course, what is intuitive coherence. After we settle those questions, we will try to show how, by applying certain probabilsitic theories of confirmation to those relations, we can arrive at a basic probabilistic theory of coherence. We will point out certain problems of that theory. At the end of the paper, we will sum up the differences between intuitive and probabilistic coherence, and we will try to provide reasons why the successful formalization of this relation, should be a desired result in epistemology.

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Sun, Shih-Jye, Miroslav Menšík, Petr Toman, Cheng-Han Chung, Chimed Ganzorig, and Jiří Pfleger. "Gate voltage impact on charge mobility in end-on stacked conjugated oligomers." Physical Chemistry Chemical Physics 22, no. 15 (2020): 8096–108. http://dx.doi.org/10.1039/c9cp06477j.

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Song, Ke, Paul Liu, Dong C. Liu, and Jian Zhan. "Applying Coherence Factor to Double-Stage Delay Multiply and Sum Beamforming in Medical Ultrasound Imaging." Journal of Medical Imaging and Health Informatics 11, no. 8 (August 1, 2021): 2155–63. http://dx.doi.org/10.1166/jmihi.2021.3765.

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The Filtered Delay Multiply and Sum (F-DMAS) beamforming algorithm has recently been proposed to improve the resolution and contrast in ultrasound imaging. Based on F-DMAS, some researchers have introduced an alternative named Double-Stage Delay Multiply and Sum (DS-DMAS), which can be considered as an enhanced version of F-DMAS. The DS-DMAS expands the DMAS algorithm to synthesize some new signals, which are then beamformed using a DMAS beamformer. However, the way to generate new signals in DS-DMAS can be thought of as a Delay and Sum (DAS) operation. There are some shortages in the DAS algorithm, so we proposed a new approach named Coherence Factor based Double-Stage Delay Multiply and Sum (DSDMAS-CF) to address these issues. The key idea of our method is to optimize the DAS operation in DSDMAS. Therefore, a modified coherence factor (CF) is applied to weight each item in DS-DMAS. The simulation, experimental and in vivo data are used to compare the performance between DAS, F-DMAS, DS-DMAS and DS-DMAS-CF. The results show that the DS-DMAS-CF gets better resolution and contrast in comparison with the other three algorithms.

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EDMONDS, BRUCE. "MODELING BELIEF CHANGE IN A POPULATION USING EXPLANATORY COHERENCE." Advances in Complex Systems 15, no. 06 (August 2012): 1250085. http://dx.doi.org/10.1142/s0219525912500853.

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A simulation model that represents belief change within a population of agents who are connected by a social network is presented based on Thagard's theory of explanatory coherence. In this model there are a fixed number of represented beliefs, each of which are either held or not by each agent. These are conceived of existing against a background of a large set of (unrepresented) shared beliefs. These beliefs are to different extents coherent with each other — this is modeled using a coherence function from possible sets of core beliefs to [-1, 1]. The social influence is achieved through gaining of a belief across a social link. Beliefs can be lost by being dropped from an agent's store. Both of these processes happen with a probability related to the change in coherence that would result in an agent's belief store. A resulting measured "opinion" can be retrieved in a number of ways, here as a weighted sum of a pattern of the core beliefs — opinion is thus an outcome and not directly processed by agents. This model suggests hypotheses about group opinion dynamics that differ from that of many established models.

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Song, Ke, Paul Liu, and Dong C. Liu. "Lag-Based Filtered-Delay Multiply and Sum Beamformer Combined with Two Phase-Related Factors for Medical Ultrasound Imaging." Computational and Mathematical Methods in Medicine 2020 (August 28, 2020): 1–10. http://dx.doi.org/10.1155/2020/1503791.

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A novel adaptive beamformer named filtered-delay multiply and sum (F-DMAS) has recently been proposed. Compared to the delay and sum (DAS) beamforming algorithm, F-DMAS can efficiently improve the resolution and contrast. However, the DAS can still be seen in the expansion of DMAS. Therefore, we rearrange the pair-wised signals in terms of lag in DMAS and then synthesize a lot of new signals. Thanks to the relationship between the spatial coherence and lag, these new signals can be thought of as sorted by the spatial coherence. Thus, we apply two phase-related factors, the polarity-based factor (PF) and the sign coherence factor (SCF), which are evaluated based on new signals, to weight the output of DMAS. The two approaches are consequently referred to as LAG-DMAS-PF and LAG-DMAS-SCF, respectively. The results show that, compared to F-DMAS and DAS, our proposed methods can improve the resolution and contrast to some extent without increasing too much computational complexity. In the comparison between LAG-DMAS-PF and LAG-DMAS-SCF, the latter has better performance, but the former can better protect image details.

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Басовская and Elena Basovskaya. "Coherence of Russian Economic System: Econometric Assessments." Economics 3, no. 2 (April 17, 2015): 21–23. http://dx.doi.org/10.12737/10838.

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The paper examines the degree of coherence of the country’s economic system through assessment of correlation between economic growth rates of regions. The author highlights the high changeability of Russia’s economic system, considered as the total sum of elements, constituted by economic systems of federal districts and economic systems of regions. Correlative relationship between economic growth rates of this system’s elements can vary in the range from positive to negative. During the periods of sustainable economic growth the degree of this system’s coherence tends to reduce sharply. High levels of coherence are typical only for crisis periods in economic development.

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Prieur, Fabrice, Ole Marius Hoel Rindal, and Andreas Austeng. "Signal Coherence and Image Amplitude With the Filtered Delay Multiply and Sum Beamformer." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 65, no. 7 (July 2018): 1133–40. http://dx.doi.org/10.1109/tuffc.2018.2831789.

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Gibson, Graham Casey, Kelly R. Moran, Nicholas G. Reich, and Dave Osthus. "Improving probabilistic infectious disease forecasting through coherence." PLOS Computational Biology 17, no. 1 (January 6, 2021): e1007623. http://dx.doi.org/10.1371/journal.pcbi.1007623.

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With an estimated $10.4 billion in medical costs and 31.4 million outpatient visits each year, influenza poses a serious burden of disease in the United States. To provide insights and advance warning into the spread of influenza, the U.S. Centers for Disease Control and Prevention (CDC) runs a challenge for forecasting weighted influenza-like illness (wILI) at the national and regional level. Many models produce independent forecasts for each geographical unit, ignoring the constraint that the national wILI is a weighted sum of regional wILI, where the weights correspond to the population size of the region. We propose a novel algorithm that transforms a set of independent forecast distributions to obey this constraint, which we refer to as probabilistically coherent. Enforcing probabilistic coherence led to an increase in forecast skill for 79% of the models we tested over multiple flu seasons, highlighting the importance of respecting the forecasting system’s geographical hierarchy.

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Giorgi, Gian Luca, and Roberta Zambrini. "Hallmarking quantum states: unified framework for coherence and correlations." Quantum 2 (December 3, 2018): 109. http://dx.doi.org/10.22331/q-2018-12-03-109.

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Quantum coherence and distributed correlations among subparties are often considered as separate, although operationally linked to each other, properties of a quantum state. Here, we propose a measure able to quantify the contributions derived by both the tensor structure of the multipartite Hilbert space and the presence of coherence inside each of the subparties. Our results hold for any number of partitions of the Hilbert space. Within this unified framework, global coherence of the state is identified as the ingredient responsible for the presence of distributed quantum correlations, while local coherence also contributes to the quantumness of the state. A new quantifier, the "hookup", is introduced within such a framework. We also provide a simple physical interpretation, in terms of coherence, of the difference between total correlations and the sum of classical and quantum correlations obtained using relative-entropy-based quantifiers.

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Lin, Jia-Chin, and Chih-Yen Liu. "Power Allocation Adaptation With Coherence Time for Nonorthogonal Multiple Access on Downlink Transmission." International Journal of Interdisciplinary Telecommunications and Networking 13, no. 3 (July 2021): 54–71. http://dx.doi.org/10.4018/ijitn.2021070104.

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Nonorthogonal multiple access (NOMA) methods are expected to improve spectral efficiency or increase sum rate in a recent mobile communication network. The performance of the power-domain NOMA highly relies on the effectiveness of successive interference cancelation (SIC) and power allocation techniques. This paper proposes an adaptive power allocation method according to analytical coherence time of time-varying channels to improve the SIC effectiveness. Simulations show that the proposed technique can improve SIC, therefore reducing error probability without reduction of the sum rate.

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Cho, Daeheum, Jérémy R. Rouxel, Markus Kowalewski, JinYong Lee, and Shaul Mukamel. "Imaging of transition charge densities involving carbon core excitations by all X-ray sum-frequency generation." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2145 (April 2019): 20170470. http://dx.doi.org/10.1098/rsta.2017.0470.

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X-ray diffraction signals from the time-evolving molecular charge density induced by selective core excitation of chemically inequivalent carbon atoms are calculated. A narrowband X-ray pulse selectively excites the carbon K-edge of the –CH 3 or –CH 2 F groups in fluoroethane (CH 3 –CH 2 F). Each excitation creates a distinct core coherence which depends on the character of the electronic transition. Direct propagation of the reduced single-electron density matrix, using real-time time-dependent density functional theory, provides the time-evolving charge density following interactions with external fields. The interplay between partially filled valence molecular orbitals upon core excitation induces characteristic femtosecond charge migration which depends on the core–valence coherence, and is monitored by the sum-frequency generation diffraction signal. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.

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Cooke, David L., and Timothy L. Cooke. "Approximating sum-of-segments axial length from a traditional optical low-coherence reflectometry measurement." Journal of Cataract & Refractive Surgery 45, no. 3 (March 2019): 351–54. http://dx.doi.org/10.1016/j.jcrs.2018.12.026.

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Bertrand, Josie-Anne, Julie Tremblay, Maryse Lassonde, Phetsamone Vannasing, Dang Khoa Nguyen, Manon Robert, Alain Bouthillier, and Franco Lepore. "Recognizing an Object from the Sum of Its Parts: An Intracranial Study on Alpha Rhythms." Journal of Cognitive Neuroscience 26, no. 8 (August 2014): 1797–805. http://dx.doi.org/10.1162/jocn_a_00582.

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Little is known about the relation of alpha rhythms and object recognition. Alpha has been generally proposed to be associated with attention and memory and to be particularly important for the mediation of long-distance communication between neuronal populations. However, how these apply to object recognition is still unclear. This study aimed at describing the spatiotemporal dynamics of alpha rhythms while recognizing fragmented images of objects presented for the first time and presented again 24 hr later. Intracranial electroencephalography was performed in six epileptic patients undergoing presurgical evaluation. Time–frequency analysis revealed a strong alpha activity, mainly of the evoked type, propagating from posterior cerebral areas to anterior regions, which was similar whether the objects were recognized or not. Phase coherence analysis, however, showed clear phase synchronization specific for the moment of recognition. Twenty-four hr later, frontal regions displayed stronger alpha activity and more distributed phase synchronization than when images were presented for the first time. In conclusion, alpha amplitude seems to be related to nonspecific mechanism. Phase coherence analysis suggests a communicational role of alpha activity in object recognition, which may be important for the comparison between bottom–up representations and memory templates.

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While, James, Andrew Jackson, Dirk Smit, and Ed Biegert. "Spectral analysis of gravity gradiometry profiles." GEOPHYSICS 71, no. 1 (January 2006): J11—J22. http://dx.doi.org/10.1190/1.2169848.

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The gravity gradient tensor (whose components are the second derivatives of the gravitational potential) is a symmetric tensor that, ignoring the constraint imposed by Laplace's equation, contains only six independent components. When measured on a horizontal plane, these components generate, in the spectral domain, six power spectral densities (PSDs) and fifteen cross-spectra. The cross-spectra can be split into two groups: a real group and a pure imaginary group. If the source distribution is statistically stationary, 1D spectra can be found from the 2D spectra via the slice theorem. The PSDs form two power-sum rules that link all gradient components. The power-sum rules, in combination with further equalities between the power and cross-spectra, reduce the number of independent spectra to 13, a number reduced to seven if the power spectrum of the potential is assumed isotropic. The power-sum rules, cross-spectral phases, and coherence between components all provide information on the internal consistency of a set of gradiometry measurements. This information can be used to assess the noise, to determine the isotropy, and, for a self-similar source, to calculate the scaling factor and average depth. When applied to a data set collected in the North Sea, the power-sum rules reveal high-frequency noise that is distributed among only three of the gradient components; additionally, the coherences reveal the source to be anisotropic with a nonzero correlation length.

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BAR-YAM, YANEER. "SUM RULE FOR MULTISCALE REPRESENTATIONS OF KINEMATICALLY DESCRIBED SYSTEMS." Advances in Complex Systems 05, no. 04 (December 2002): 409–31. http://dx.doi.org/10.1142/s0219525902000638.

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We derive a sum rule that constrains the scale based decomposition of the trajectories of finite systems of particles. The sum rule reflects a tradeoff between the finer and larger scale collective degrees of freedom. For short duration trajectories, where acceleration is irrelevant, the sum rule can be related to the moment of inertia and the kinetic energy (times a characteristic time squared). Thus, two nonequilibrium systems that have the same kinetic energy and moment of inertia can, when compared to each other, have different scales of behavior, but if one of them has larger scales of behavior than the other, it must compensate by also having smaller scales of behavior. In the context of coherence or correlation, the larger scale of behavior corresponds to the collective motion, while the smaller scales of behavior correspond to the relative motion of correlated particles. For longer duration trajectories, the sum rule includes the full effective moment of inertia of the system in space-time with respect to an external frame of reference, providing the possibility of relating the class of systems that can exist in the same space-time domain.

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Lou, Cuijuan, Chunyu Li, Shanshan Wang, Mingyue Ding, and Ming Yuchi. "Filtered Delay Multiply and Sum Combined with Space-Time Smoothing Coherence Factor in Ultrasound Imaging." Journal of Medical Imaging and Health Informatics 7, no. 7 (November 1, 2017): 1648–53. http://dx.doi.org/10.1166/jmihi.2017.2180.

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Keil, Frank C. "On Being More than the Sum of the Parts: The Conceptual Coherence of Cognitive Science." Psychological Science 2, no. 5 (September 1991): 283–93. http://dx.doi.org/10.1111/j.1467-9280.1991.tb00154.x.

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Davis, Ian, and Gareth J. Bennett. "Spectral, modal and coherence analysis of sum and difference scattering of narrowband noise in turbomachinery." International Journal of Aeroacoustics 15, no. 1-2 (March 2016): 180–206. http://dx.doi.org/10.1177/1475472x16630860.

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Alsabah, Muntadher, Marwah Abdulrazzaq Naser, Basheera M. Mahmmod, Nor K. Noordin, and Sadiq H. Abdulhussain. "Sum Rate Maximization Versus MSE Minimization in FDD Massive MIMO Systems With Short Coherence Time." IEEE Access 9 (2021): 108793–808. http://dx.doi.org/10.1109/access.2021.3100799.

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Schmieke, Marcus. "Quantum Entangled Frequencies and Coherence in Bioenergetic Systems." Dev Sanskriti Interdisciplinary International Journal 18 (July 31, 2021): 10–33. http://dx.doi.org/10.36018/dsiij.v18i.226.

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Holistic Health can be understood as the coherence of the human being as a whole including his organism, mind, and relationship to his environment. Quantum entanglement of subsystems on all levels of the human being is responsible for the wholeness of the living entity. The sum total of entanglements is defined here as an individual Information Field which corresponds to the ancient vedic concept of akasha. Entangled frequencies might be able to resonate with and influence human bioenergetic processes and systems with the aim of creating coherence of the bioenergetic system, both within the individual and between the individual and the surrounding fields. Here a bioenergetic process is proposed that uses entangled frequencies to increase the coherence of living systems selected through biofeedback of a Quantum Noise Generator, which seems to be correlated to the ancient vedic concept of prana. It has been tested in a controlled observation study for its effect on the sense of coherence of 3545 participants. The promising results of this study are additionally presented here.

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Shen, Che-Chou, and Yen-Chen Chu. "DMAS Beamforming with Complementary Subset Transmit for Ultrasound Coherence-Based Power Doppler Detection in Multi-Angle Plane-Wave Imaging." Sensors 21, no. 14 (July 16, 2021): 4856. http://dx.doi.org/10.3390/s21144856.

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Conventional ultrasonic coherent plane-wave (PW) compounding corresponds to Delay-and-Sum (DAS) beamforming of low-resolution images from distinct PW transmit angles. Nonetheless, the trade-off between the level of clutter artifacts and the number of PW transmit angle may compromise the image quality in ultrafast acquisition. Delay-Multiply-and-Sum (DMAS) beamforming in the dimension of PW transmit angle is capable of suppressing clutter interference and is readily compatible with the conventional method. In DMAS, a tunable p value is used to modulate the signal coherence estimated from the low-resolution images to produce the final high-resolution output and does not require huge memory allocation to record all the received channel data in multi-angle PW imaging. In this study, DMAS beamforming is used to construct a novel coherence-based power Doppler detection together with the complementary subset transmit (CST) technique to further reduce the noise level. For p = 2.0 as an example, simulation results indicate that the DMAS beamforming alone can improve the Doppler SNR by 8.2 dB compared to DAS counterpart. Another 6-dB increase in Doppler SNR can be further obtained when the CST technique is combined with DMAS beamforming with sufficient ensemble averaging. The CST technique can also be performed with DAS beamforming, though the improvement in Doppler SNR and CNR is relatively minor. Experimental results also agree with the simulations. Nonetheless, since the DMAS beamforming involves multiplicative operation, clutter filtering in the ensemble direction has to be performed on the low-resolution images before DMAS to remove the stationary tissue without coupling from the flow signal.

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Hu, Wei, and Bing Si. "Technical Note: Improved partial wavelet coherency for understanding scale-specific and localized bivariate relationships in geosciences." Hydrology and Earth System Sciences 25, no. 1 (January 19, 2021): 321–31. http://dx.doi.org/10.5194/hess-25-321-2021.

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Abstract. Bivariate wavelet coherency is a measure of correlation between two variables in the location–scale (spatial data) or time–frequency (time series) domain. It is particularly suited to geoscience, where relationships between multiple variables differ with locations (times) and/or scales (frequencies) because of the various processes involved. However, it is well-known that bivariate relationships can be misleading when both variables are dependent on other variables. Partial wavelet coherency (PWC) has been proposed to detect scale-specific and localized bivariate relationships by excluding the effects of other variables but is limited to one excluding variable and provides no phase information. We aim to develop a new PWC method that can deal with multiple excluding variables and provide phase information. Both stationary and non-stationary artificial datasets with the response variable being the sum of five cosine waves at 256 locations are used to test the method. The new method was also applied to a free water evaporation dataset. Our results verified the advantages of the new method in capturing phase information and dealing with multiple excluding variables. Where there is one excluding variable, the new PWC implementation produces higher and more accurate PWC values than the previously published PWC implementation that mistakenly considered bivariate real coherence rather than bivariate complex coherence. We suggest the PWC method is used to untangle scale-specific and localized bivariate relationships after removing the effects of other variables in geosciences. The PWC implementations were coded with Matlab and are freely accessible (https://figshare.com/s/bc97956f43fe5734c784, last access: 14 January 2021).

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Kim, Seong-Hu, and Yong-Hwa Park. "Interaural Coherence Estimation for Speech Processing in Reverberant Environment." Applied Sciences 10, no. 3 (January 22, 2020): 769. http://dx.doi.org/10.3390/app10030769.

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Interaural coherence is used to quantify the effects of reverberation on speech, and previous studies applied the conventional method using all previous time data in the form of an infinite impulse response filter to estimate interaural coherence. To consider a characteristic of speech that continuously changes over time, this paper proposes a new method of estimating interaural coherence using time data within a finite length of speech, which is called the quasi-steady interval. The length of the quasi-steady interval is determined with various frequency bands, reverberation times, and short-time Fourier transform (STFT) variables through numerical experiment, and it decreased as reverberation time decreased and the frequency increased. In this interval, a diffuse speech, which is an infinite sum of reflected speeches of different propagating paths, is uncorrelated between two microphones apart from each other; thus, the coherence is close to zero. However, a direct speech measured at the two microphones has steady amplitude and phase difference in this internal; thus, the coherence is close to one. Moreover, the new method is the form of a finite impulse response filter that has a linear phase delay or zero phase delay with respect to speech to frequency; thus, the same or zero time delay for each frequency is applied to the power spectral density. Therefore, the coherence estimation of the new method is closer to the ideal value than the conventional one, and the coherence is accurately estimated at the time–frequency bins of direct speech, which is time-varying according to speech variation.

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Ushiyama, Junichi, Tatsuya Suzuki, Yoshihisa Masakado, Kimitaka Hase, Akio Kimura, Meigen Liu, and Junichi Ushiba. "Between-subject variance in the magnitude of corticomuscular coherence during tonic isometric contraction of the tibialis anterior muscle in healthy young adults." Journal of Neurophysiology 106, no. 3 (September 2011): 1379–88. http://dx.doi.org/10.1152/jn.00193.2011.

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Oscillatory activity of the sensorimotor cortex has been reported to show coherence with muscle activity in the 15- to 35-Hz frequency band (β-band) during weak to moderate intensity of isometric contraction. The present study examined the variance of the magnitude of the corticomuscular coherence across a large number of subjects. We quantified the coherence between EEG over the sensorimotor cortex and rectified electromyogram (EMG) from the tibialis anterior muscle during tonic isometric contraction at 30% of maximal effort in 100 healthy young individuals. We estimated the maximal peak of EEG-EMG coherence (Cohmax) and the ratio of the sum of the autopower spectral density function within the β-band to that of all frequency ranges for both EEG (EEGβ-PSD) and EMG (EMGβ-PSD) signals. The frequency histogram of Cohmax across all subjects showed a broad bell-shaped continuous distribution (range, 0.048–0.816). When the coherence was thresholded at the estimated significance level of P < 0.05 (0.114), 46 out of 100 subjects showed significant EEG-EMG coherence. Cohmax occurred within the β-band in the majority of subjects who showed significant EEG-EMG coherence ( n = 43). Furthermore, Cohmax showed significant positive correlations with both EEGβ-PSD ( r = 0.575, P < 0.001) and EMGβ-PSD ( r = 0.606, P < 0.001). These data suggest that even during simple tonic isometric contraction, the strength of oscillatory coupling between the sensorimotor cortex and spinal motoneurons varies among individuals and is a contributory factor determining muscle activation patterns such as the degree of grouped discharge in muscle activity within the β-band for each subject.

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Ushiyama, Junichi, Masanori Katsu, Yoshihisa Masakado, Akio Kimura, Meigen Liu, and Junichi Ushiba. "Muscle fatigue-induced enhancement of corticomuscular coherence following sustained submaximal isometric contraction of the tibialis anterior muscle." Journal of Applied Physiology 110, no. 5 (May 2011): 1233–40. http://dx.doi.org/10.1152/japplphysiol.01194.2010.

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Oscillatory activity of the sensorimotor cortex shows coherence with muscle activity within the 15- to 35-Hz frequency band (β-band) during weak to moderate sustained isometric contraction. We aimed to examine the acute changes in this corticomuscular coupling due to muscle fatigue and its effect on the steadiness of the exerted force. We quantified the coherence between the electroencephalogram (EEG) recorded over the sensorimotor cortex and the rectified surface electromyogram (EMG) of the tibialis anterior muscle as well as the coefficient of variance of the dorsiflexion force (ForceCV) and sum of the auto-power spectral density function of the force within the β-band (Forceβ-PSD) during 30% of maximal voluntary contraction (MVC) for 60 s before (prefatiguing task) and after (postfatiguing task) muscle fatigue induced by sustained isometric contraction at 50% of MVC until exhaustion in seven healthy male subjects. The magnitude of the EEG-EMG coherence increased in the postfatiguing task in six of seven subjects. The maximal peak of EEG-EMG coherence stayed within the β-band in both pre- and postfatiguing tasks. Interestingly, two subjects, who had no significant EEG-EMG coherence in the prefatiguing task, showed significant coherence in the postfatiguing task. Additionally, ForceCV and Forceβ-PSD significantly increased after muscle fatigue. These data suggest that when muscle fatigue develops, the central nervous system enhances oscillatory muscular activity in the β-band stronger coupled with the sensorimotor cortex activity accomplishing the sustained isometric contraction at lower performance levels.

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Weill, Yishay, Koby Brosh, Tamar Levi Vineberg, Yoel Arieli, Avi Caspi, Michael J. Potter, David Zadok, and Joel Hanhart. "Enhanced depth imaging in swept-source optical coherence tomography: Improving visibility of choroid and sclera, a masked study." European Journal of Ophthalmology 30, no. 6 (July 26, 2019): 1295–300. http://dx.doi.org/10.1177/1120672119863560.

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Purpose To compare enhanced depth imaging in swept-source optical coherence tomography and non–enhanced depth imaging optical coherence tomography in their ability to capture choroidal and scleral details. Methods Averaged foveal B-Scans were obtained from 40 eyes of 20 healthy volunteers by swept-source optical coherence tomography with and without enhanced depth imaging. Visibility and contrast of vascular details within the choroid, choroidoscleral junction, and sclera were evaluated by masked readers using an ordinal scoring scale. Outcomes were analyzed using the Wilcoxon signed rank-sum test. Results Visibility of the choroidal vascular details ( Z = 5.94, p < .001), the choroidoscleral junction ( Z = 5.85, p < .001), and the sclera ( Z = 6.80, p < .001) was significantly higher with enhanced depth imaging than with non–enhanced depth imaging swept-source optical coherence tomography. Similarly, image contrast was significantly higher with enhanced depth imaging than with non–enhanced depth imaging swept-source optical coherence tomography for the choroidal vascular details ( Z = 9.47, p < .001), for the choroidoscleral junction ( Z = 9.28, p < .001), and for the sclera ( Z = 9.42, p < .001). Conclusion Enhanced depth imaging applied to swept-source optical coherence tomography–averaged foveal B-scans enhances visualization of the choroidal details, of the choroidoscleral junction, and of the sclera. This novel modality can easily be implemented in clinics and could improve our understanding of conditions involving the choroid or the sclera.

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Wati, Ismi Isma, Sri Mulyati Mulyati, and Khusnul Khotimah Khotimah. "KOHESI DAN KOHERENSI DALAM NOVEL KKN DI DESA PENARI KARYA SIMPLEMAN DAN IMPLIKASINYA TERHADAP PEMBELAJARAN BAHASA INDONESIA DI SMA." Jubindo: Jurnal Ilmu Pendidikan Bahasa dan Sastra Indonesia 5, no. 3 (January 26, 2021): 123–31. http://dx.doi.org/10.32938/jbi.v5i3.612.

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Cohesion and coherence have an important role in writing essays, both those that will write or those that have become essays. Therefore this study aims to determine the use of cohesion and coherence in the KKN novel in Penari Village. The object of this research is the KKN novel in Penari Village by Simpleman. The subject of this research is the sentence which contains the type of cohesion and coherence in the KKN novel in Penari Village by Simpleman. The approach used is a qualitative approach. A qualitative approach is an approach that presents data in the form of sentences. The design of this research is by collecting data, then the data is grouped according to the use of cohesion and coherence types, then the data is analyzed and presented in an informal form. Data collection techniques using reading techniques and note taking techniques. The technique of presenting the results of the analysis using informal techniques. Informal techniques are techniques that present data in the form of common words that are easily understood by the reader. The results of this study are grammatical cohesion, lexical cohesion and coherence types. Grammatical cohesion includes: reference, substitution, ellipsis, and conjunction. The use of lexical cohesion are of two types namely, repetition and collocation. The use of coherence there are five relationships, namely: the sum relationship, the sequential relationship, the resistance relationship, the causal relationship, and the time relationship.

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Loo, E., K. Sinx, J. Welzel, S. Schuh, N. Kelleners-Smeets, K. Mosterd, and P. Nelemans. "Cumulative Sum Analysis for the Learning Curve of Optical Coherence Tomography Assisted Diagnosis of Basal Cell Carcinoma." Acta Dermato Venereologica 100, no. 19 (2020): adv00343. http://dx.doi.org/10.2340/00015555-3696.

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Shen, Che-Chou, and Kuan-Lin Tu. "Ultrasound DMAS Beamforming for Estimation of Tissue Speed of Sound in Multi-Angle Plane-Wave Imaging." Applied Sciences 10, no. 18 (September 10, 2020): 6298. http://dx.doi.org/10.3390/app10186298.

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Various methods have been proposed to estimate the tissue speed of sound (SOS) of propagating medium using the curvature of received channel waveform or the analysis of resultant image quality. In our previous study, baseband delay-multiply-and-sum (DMAS) beamforming methods have been developed for multi-angle plane-wave (PW) imaging which relies on signal coherence among transmit events (Tx-DMAS) or receive channel (Rx-DMAS) or both (2D-DMAS) to suppress low-coherence clutters. In this study, we further extend our DMAS beamforming to quantify the level of signal coherence for determining the average SOS in multi-angle PW imaging. The signal coherence in multi-angle PW imaging is represented as the DMAS coherence factor (DCF) which can be easily estimated from the magnitude ratio of the pixel value of DMAS image to that of DAS image. By searching the beamforming velocity that provides the highest signal coherence of echo matrix, the average tissue SOS of the imaged object can be determined. For the PICMUS experimental dataset, the optimal beamforming velocity (Copt) estimated by the proposed DCF method does provide the best image quality. For the Prodigy dataset, the estimated tissue SOS is 1426 ± 6 m/s which is very close to the actual tissue SOS of 1427 m/s and the estimated SOS also corresponds to the Copt with the minimal −6-dB lateral width and the maximal contrast within an error of 10 m/s. Estimation of tissue SOS in the proposed DCF method is also robust even in the presence of transmit delay error due to deviation of SOS.

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HEDBERG, MICHAEL. "A coherence theorem for Martin-Löf's type theory." Journal of Functional Programming 8, no. 4 (July 1998): 413–36. http://dx.doi.org/10.1017/s0956796898003153.

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In type theory a proposition is represented by a type, the type of its proofs. As a consequence, the equality relation on a certain type is represented by a binary family of types. Equality on a type may be conventional or inductive. Conventional equality means that one particular equivalence relation is singled out as the equality, while inductive equality – which we also call identity – is inductively defined as the ‘smallest reflexive relation’. It is sometimes convenient to know that the type representing a proposition is collapsed, in the sense that all its inhabitants are identical. Although uniqueness of identity proofs for an arbitrary type is not derivable inside type theory, there is a large class of types for which it may be proved. Our main result is a proof that any type with decidable identity has unique identity proofs. This result is convenient for proving that the class of types with decidable identities is closed under indexed sum. Our proof of the main result is completely formalized within a kernel fragment of Martin-Löf's type theory and mechanized using ALF. Proofs of auxiliary lemmas are explained in terms of the category theoretical properties of identity. These suggest two coherence theorems as the result of rephrasing the main result in a context of conventional equality, where the inductive equality has been replaced by, in the former, an initial category structure and, in the latter, a smallest reflexive relation.

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Jeon, Seungwan, Eun-Yeong Park, Wonseok Choi, Ravi Managuli, Ki jong Lee, and Chulhong Kim. "Real-time delay-multiply-and-sum beamforming with coherence factor for in vivo clinical photoacoustic imaging of humans." Photoacoustics 15 (September 2019): 100136. http://dx.doi.org/10.1016/j.pacs.2019.100136.

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DAI, MEIFENG, XIAOQIAN WANG, YUE ZONG, JIAHUI ZOU, YUFEI CHEN, and WEIYI SU. "FIRST-ORDER NETWORK COHERENCE AND EIGENTIME IDENTITY ON THE WEIGHTED CAYLEY NETWORKS." Fractals 25, no. 05 (September 4, 2017): 1750049. http://dx.doi.org/10.1142/s0218348x17500499.

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In this paper, we first study the first-order network coherence, characterized by the entire mean first-passage time (EMFPT) for weight-dependent walk, on the weighted Cayley networks with the weight factor. The analytical formula of the EMFPT is obtained by the definition of the EMFPT. The obtained results show that the scalings of first-order coherence with network size obey four laws along with the range of the weight factor. Then, we study eigentime identity quantifying as the sum of reciprocals of all nonzero normalized Laplacian eigenvalues on the weighted Cayley networks with the weight factor. We show that all their eigenvalues can be obtained by calculating the roots of several small-degree polynomials defined recursively. The obtained results show that the scalings of the eigentime identity on the weighted Cayley networks obey two laws along with the range of the weight factor.

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Kooi, Frank L., Karen K. De Valois, Eugene Switkes, and David H. Grosof. "Higher-Order Factors Influencing the Perception of Sliding and Coherence of a Plaid." Perception 21, no. 5 (October 1992): 583–98. http://dx.doi.org/10.1068/p210583.

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The effect of several new stimulus parameters on the perception of a moving plaid pattern (the sum of two sine-wave gratings) were tested. It was found that: (i) the degree of perceived sliding is strongly influenced by the aperture configuration through which the plaid is viewed; (ii) the chromaticity of the sinusoidal components affects coherence in that more sliding is observed when the plaid components differ in hue, and there is less sliding when they are of the same hue; (iii) equiluminant plaids made of components equal in color almost never show any sliding; and (iv) sliding increases with viewing time. The coherence—sliding percept must therefore be influenced by color, by global interactions, and by adaptation or learning effects, thus suggesting a higher-level influence. These results are most easily modelled by separating the decision to carry out recombination from the process of recombination.

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Pulella, Andrea, Rodrigo Aragão Santos, Francescopaolo Sica, Philipp Posovszky, and Paola Rizzoli. "Multi-Temporal Sentinel-1 Backscatter and Coherence for Rainforest Mapping." Remote Sensing 12, no. 5 (March 6, 2020): 847. http://dx.doi.org/10.3390/rs12050847.

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This paper reports recent advancements in the field of Synthetic Aperture Radar (SAR) for forest mapping by using interferometric short-time-series. In particular, we first present how the interferometric capabilities of the Sentinel-1 satellites constellation can be exploited for the monthly mapping of the Amazon rainforest. Indeed, the evolution in time of the interferometric coherence can be properly modeled as an exponential decay and the retrieved interferometric parameters can be used, together with the backscatter, as input features to the machine learning Random Forests classifier. Furthermore, we present an analysis on the benefits of the use of textural information, derived from Sentinel-1 backscatter, in order to enhance the classification accuracy. These textures are computed through the Sum And Difference Histograms methodology and the final classification accuracy, resulting by adding them to the aforementioned features, is a thematic map that exceeds an overall agreement of 85 % , when validated using the optical external reference Finer Resolution Observation and Monitoring of Global Land Cover (FROM-GLC) map. The experiments presented in the final part of the paper are enriched with a further analysis and discussion on the selected scenes using updated multispectral Sentinel-2 acquisitions.

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Kallenberg, Kjell, Gerry Larsson, and Björn Söderfeldt. "View of Life and Health." Archive for the Psychology of Religion 22, no. 1 (January 1997): 237–49. http://dx.doi.org/10.1163/157361297x00171.

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The quest for causes behind health and sickness proposes deeper causes like per- sonality and general view of life. Two such concepts have been shown to associate with health indicators in a systematic way, sense of coherence and view of life. Sense of coherence (SOC) is defined as the sum of three factors, comprehensibility, manage- ability, and meaningfulness. View of life (VOL) consists of three components, general theories of man and the world, a central value system, and a basic attitude. Two em- pirical studies are summarized where the concepts are related to bereavement and health, respectively. It is concluded that there are many similarities between the two concepts. They both emphasize integration and coherence and connote basic struc- tures in belief systems. They can be related to personality structure and the coping process. The concepts differ in scope and depth. SOC can be considered as part of the connotation of VOL. SOC is quantitatively measurable while VOL presumes qualitative methods of assessment. In studies of health, where factors pertaining to world view or sense of coherence are not in focus, but studied rather as possible confoun- ders, methodological simplicity points to use of the SOC concept. In studies of health where the deeper causal structures are in focus, VOL should also be used, since it per- mits greater depth of analysis. Ideally, both concepts should be applied for a full un- derstanding between man's inner processes and health.

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Spadin, Florentin, Michael Jaeger, Robert Nuster, Pavel Subochev, and Martin Frenz. "Quantitative comparison of frequency-domain and delay-and-sum optoacoustic image reconstruction including the effect of coherence factor weighting." Photoacoustics 17 (March 2020): 100149. http://dx.doi.org/10.1016/j.pacs.2019.100149.

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WANG, XIAOQIAN, HUILING XU, and CHANGBING MA. "CONSENSUS PROBLEMS IN WEIGHTED HIERARCHICAL GRAPHS." Fractals 27, no. 06 (September 2019): 1950086. http://dx.doi.org/10.1142/s0218348x19500865.

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We present the hierarchical graph for the growth of weighted networks in which the structural growth is coupled with the edges’ weight dynamical evolution. We investigate consensus problems of the graph from weighted Laplacian spectra perspective, focusing on three important quantities of consensus problems, convergence speed, delay robustness, and first-order coherence, which are determined by the second smallest eigenvalue, largest eigenvalue, and sum of reciprocals of each nonzero eigenvalue of weighted Laplacian matrix, respectively. Unlike previous enquiries, we want to emphasize the importance of weight factor in the study of coherence problems. In what follows, we attempt to study that the weighted Laplacian eigenvalues of the weighted hierarchical graphs, which are determined through analytic recursive equations. We find in our study that the value of convergence speed and delay robustness in weighted hierarchical graphs increases as weight factor increases and the value of first-order coherence decreases as weight factor increases. Moreover, as is expected, weight factor affects the performance of consensus behavior and can be regarded as a leverage in the problem of consensus problems. This paper puts forward the proposal and the countermeasure for stability optimization of networks from the perspective of weight factor for future researchers.

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Ivanovic, Jelena. "Geometrical realisations of the simple permutoassociahedron by Minkowski sums." Applicable Analysis and Discrete Mathematics 14, no. 1 (2020): 55–93. http://dx.doi.org/10.2298/aadm190414011i.

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This paper introduces a family of n-polytopes, PAn,c which is a geometrical realisation of simple permutoassociahedra. It has significant importance serving as a topological proof of Mac Lane's coherence. Polytopes in this family are defined as Minkowski sums of certain polytopes such that every summand produces exactly one truncation of the permutohedron, i.e. yields to the appropriate facet of the resulting sum. Additionally, it leads to the correlation between Minkowski sums and truncations, which gives a general procedure for similar geometrical realisation of a wider class of polytopes.

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Xiao, Jianbo, Yu-Qiong Niu, Steven Wiesner, and Xin Huang. "Normalization of neuronal responses in cortical area MT across signal strengths and motion directions." Journal of Neurophysiology 112, no. 6 (September 15, 2014): 1291–306. http://dx.doi.org/10.1152/jn.00700.2013.

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Multiple visual stimuli are common in natural scenes, yet it remains unclear how multiple stimuli interact to influence neuronal responses. We investigated this question by manipulating relative signal strengths of two stimuli moving simultaneously within the receptive fields (RFs) of neurons in the extrastriate middle temporal (MT) cortex. Visual stimuli were overlapping random-dot patterns moving in two directions separated by 90°. We first varied the motion coherence of each random-dot pattern and characterized, across the direction tuning curve, the relationship between neuronal responses elicited by bidirectional stimuli and by the constituent motion components. The tuning curve for bidirectional stimuli showed response normalization and can be accounted for by a weighted sum of the responses to the motion components. Allowing nonlinear, multiplicative interaction between the two component responses significantly improved the data fit for some neurons, and the interaction mainly had a suppressive effect on the neuronal response. The weighting of the component responses was not fixed but dependent on relative signal strengths. When two stimulus components moved at different coherence levels, the response weight for the higher-coherence component was significantly greater than that for the lower-coherence component. We also varied relative luminance levels of two coherently moving stimuli and found that MT response weight for the higher-luminance component was also greater. These results suggest that competition between multiple stimuli within a neuron's RF depends on relative signal strengths of the stimuli and that multiplicative nonlinearity may play an important role in shaping the response tuning for multiple stimuli.

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Yang, Guang, Eghbal Amidi, and Quing Zhu. "Photoacoustic tomography reconstruction using lag-based delay multiply and sum with a coherence factor improves in vivo ovarian cancer diagnosis." Biomedical Optics Express 12, no. 4 (March 23, 2021): 2250. http://dx.doi.org/10.1364/boe.417525.

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Journal articles on the topic 'Sum of coherence'

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