Articles de revues : « Echo-optimization »

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Zhang, Q. « Echo optimization of cardiac resynchronization therapy ». International Journal of Cardiology 125 (février 2008) : S15. http://dx.doi.org/10.1016/s0167-5273(08)70158-x.

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Johnson, G., et E. X. Wu. « Sensitivity Optimization of Echo Times and Data Sampling Times for Spin-Echo Spectroscopy ». Journal of Magnetic Resonance, Series B 105, n^o 3 (novembre 1994) : 238–41. http://dx.doi.org/10.1006/jmrb.1994.1130.

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R., Vincy, et J. William. « Optimization of Acoustic Echo and Noise Reduction in Non Stationary Environment ». International Journal of Advance Research and Innovation 3, n^o 1 (2015) : 104–8. http://dx.doi.org/10.51976/ijari.311519.

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Optimized speech enhancement method combines acoustic echo reduction and noise reduction in a unified framework for non stationary environment. Simultaneous optimization of noise and echo reduction is already done in stationary environment. In most of the times in transmission, signal properties change over time. We need to remove the artifacts of sound in those conditions. Recursive least square method proposed for noise and echo reduction. It gives little amount of mean square error and better results. Normally, partial optimization of acoustic echo reduction and noise reduction does not lead to total optimization. A cascade method of multiple functions causes mutual interference between these functions and degrades eventual speech enhancement performance. Unlike cascade methods, the proposed method combines all functions to optimize eventual speech enhancement performance based on a unified framework, which is also robust against the mutual interference problem. With the proposed method, in addition to time-invariant linear filters, time-varying filters are used to reduce residual acoustic echo signal, and background noise signal which cannot be reduced using time-invariant filters. These time-invariant filters and time-varying filters are also optimized based on a unified likelihood function to avoid the mutual interference problem. Under this, all the parameters are optimized simultaneously based on the expectation-maximization algorithm and calculates a minimum mean squared error estimate of a desired signal. The experimental results show that the proposed method is superior to the cascade methods.

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Thiede, Luca Anthony, et Ulrich Parlitz. « Gradient based hyperparameter optimization in Echo State Networks ». Neural Networks 115 (juillet 2019) : 23–29. http://dx.doi.org/10.1016/j.neunet.2019.02.001.

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Gowland, P. A., et R. Bowtell. « Theoretical optimization of multi-echo fMRI data acquisition ». Physics in Medicine and Biology 52, n^o 7 (2 mars 2007) : 1801–13. http://dx.doi.org/10.1088/0031-9155/52/7/003.

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Vidarsson, Logi, Steven M. Conolly, Kelvin O. Lim, Garry E. Gold et John M. Pauly. « Echo time optimization for linear combination myelin imaging ». Magnetic Resonance in Medicine 53, n^o 2 (2005) : 398–407. http://dx.doi.org/10.1002/mrm.20360.

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Xue, Yu, Qi Zhang et Adam Slowik. « Automatic topology optimization of echo state network based on particle swarm optimization ». Engineering Applications of Artificial Intelligence 117 (janvier 2023) : 105574. http://dx.doi.org/10.1016/j.engappai.2022.105574.

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Hu, Haofei, Chongyi Fan et Xiaotao Huang. « Radar Target Detection Based on Waveform Design under Atmospheric Attenuation ». Journal of Physics : Conference Series 2290, n^o 1 (1 juin 2022) : 012071. http://dx.doi.org/10.1088/1742-6596/2290/1/012071.

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Abstract Under the condition of atmospheric attenuation, the mismatch of radar echo signals leads to the decrease of signal-to-noise ratio (SNR) and detection probability. A joint optimization algorithm for transmitting signal and receiving filter of MIMO radar with atmospheric system response is presented in this paper. Considering the energy constraint, similarity constraint and spectral coexistence constraint of the transmitting signal, and introducing the atmospheric channel response matrix, the echo model under the atmospheric response condition is constructed. By optimizing the transmitting signal and the receiving filter, the echo signal SNR and radar detection probability can be improved. On this basis, the ARMA stochastic model is used to simulate the atmospheric system response. Solve non-convex problems by matrix optimization, positive semi-definite relaxation, Charnes-Cooper transformation, and loop optimization methods. Finally, the rank-one matrix decomposition method is used to extract the optimal signal from the signal autocorrelation matrix. And we analyze the convergence of the algorithm, the degree of SNR improvement and the detection probability. Through numerical experiments, it is proved that after the atmospheric channel response is introduced and matched correctly, the SNR of the echo signal can be improved and the radar detection probability can be greatly increased.

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Armenio, Luca Bugliari, Lorenzo Fagiano, Enrico Terzi, Marcello Farina et Riccardo Scattolini. « Optimal Training of Echo State Networks via Scenario Optimization ». IFAC-PapersOnLine 53, n^o 2 (2020) : 5183–88. http://dx.doi.org/10.1016/j.ifacol.2020.12.1187.

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Liu, Junxiu, Tiening Sun, Yuling Luo, Su Yang, Yi Cao et Jia Zhai. « Echo state network optimization using binary grey wolf algorithm ». Neurocomputing 385 (avril 2020) : 310–18. http://dx.doi.org/10.1016/j.neucom.2019.12.069.

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Li, Dingyuan, Fu Liu, Junfei Qiao et Rong Li. « Structure optimization for echo state network based on contribution ». Tsinghua Science and Technology 24, n^o 1 (février 2019) : 97–105. http://dx.doi.org/10.26599/tst.2018.9010049.

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Rekveldt, M. Theo, Chris P. Duif, Wicher H. Kraan, Jeroen Plomp et Wim G. Bouwman. « Polarization optimization of spin-echo small angle scattering instruments ». Review of Scientific Instruments 79, n^o 1 (janvier 2008) : 015113. http://dx.doi.org/10.1063/1.2832350.

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KIMOTO, MASANORI, et TAKUYA ASAMI. « Multichannel Acoustic Echo Canceler Based on Particle Swarm Optimization ». Electronics and Communications in Japan 99, n^o 6 (12 mai 2016) : 31–40. http://dx.doi.org/10.1002/ecj.11818.

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Lorusso, R., G. La Canna, M. Gargano, M. Zogno, L. Sandrelli, C. Cingia, P. Marzollo, O. Visioli et O. Alfieri. « Wrapped muscle activation time optimization by echo-doppler assessment ». Journal of Cardiothoracic and Vascular Anesthesia 8, n^o 3 (juin 1994) : 50. http://dx.doi.org/10.1016/1053-0770(94)90453-7.

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Perzanowski, Christian. « Is echo-guided optimization of biventricular devices time practical ? » International Journal of Cardiology 148, n^o 1 (avril 2011) : 114–15. http://dx.doi.org/10.1016/j.ijcard.2011.01.043.

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Liu, Wen-Jie, Yu-Ting Bai, Xue-Bo Jin, Jian-Lei Kong et Ting-Li Su. « A Novel Broad Echo State Network for Time Series Prediction : Cascade of Mapping Nodes and Optimization of Enhancement Layer ». Applied Sciences 12, n^o 13 (23 juin 2022) : 6396. http://dx.doi.org/10.3390/app12136396.

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Time series prediction is crucial for advanced control and management of complex systems, while the actual data are usually highly nonlinear and nonstationary. A novel broad echo state network is proposed herein for the prediction problem of complex time series data. Firstly, the framework of the broad echo state network with cascade of mapping nodes (CMBESN) is designed by embedding the echo state network units into the broad learning system. Secondly, the number of enhancement layer nodes of the CMBESN is determined by proposing an incremental algorithm. It can obtain the optimal network structure parameters. Meanwhile, an optimization method is proposed based on the nonstationary statistic metrics to determine the enhancement layer. Finally, experiments are conducted both on the simulated and actual datasets. The results show that the proposed CMBESN and its optimization have good prediction capability for nonstationary time series data.

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Zhao, Wei, et Chun Peng Dong. « The Complex Blind Deflation Algorithm Based Particle Swarm Optimization with Survival of the Fittest Mechanism ». Applied Mechanics and Materials 347-350 (août 2013) : 2656–60. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.2656.

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For multi-constraint nonlinear optimization, this paper puts forward a complex blind deflation algorithm based particle swarm optimization with survival of the fittest mechanism (CBD-PSOSFM) which has faster convergence speed, and then gives a quantificational formula of the improved convergence speed, discusses implement method and the rule of parameters design; Because of the blind source separation (BSS) optimization characteristic in nature, the algorithm can be used to implement semi-BSS with nonlinear multi-constraint. For active object echo detection, the paper sets up fitness function with the multi-constraint like as kurtosis, energy and outline and forms the complex blind deflation algorithm. Finally, the simulation experiment of blind deflation to complex echo validates the algorithms validity and faster convergence capability.

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Baravi, Talia, Ofer Feinerman et Oren Raz. « Echo chambers in the Ising model and implications on the mean magnetization ». Journal of Statistical Mechanics : Theory and Experiment 2022, n^o 4 (1 avril 2022) : 043402. http://dx.doi.org/10.1088/1742-5468/ac5d42.

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Abstract The echo-chamber effect is a common term in opinion dynamic modeling to describe how a person’s opinion might be artificially enhanced as it is reflected back at her through social interactions. Here, we study the existence of this effect in statistical mechanics models, which are commonly used to study opinion dynamics. We show that the Ising model does not exhibit echo-chambers, but this result is a consequence of a special symmetry. We then distinguish between three types of models: (i) those with a strong echo-chamber symmetry, that have no echo-chambers at all; (ii) those with a weak echo-chamber symmetry that can exhibit echo-chambers but only if there are external fields in the system, and (iii) models without echo-chamber symmetry that generically have echo-chambers. We use these results to construct an efficient algorithm to efficiently and precisely calculate magnetization in arbitrary tree networks. Finally, we apply this algorithm to study two systems: phase transitions in the random field Ising model on a Bethe lattice and the influence optimization problem in social networks.

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Xue, Mingxi. « Optimization and Design of Integrated Space Target ». Open Electrical & ; Electronic Engineering Journal 11, n^o 1 (20 juillet 2017) : 125–40. http://dx.doi.org/10.2174/1874129001711010125.

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Background & Objective: The design and optimization of laser detection system based on MEMS (Micro-electro Mechanical Systems) scanning mirror is presented in the paper. According to requirements of application, it adopts the laser module to design the laser driver circuit, and the designed modulation circuit can satisfy the actual needs. Method: The designed information processing module is composed of the echo receiving module, signal amplification and filter circuit module, and the synchronous circuit of measuring angle and distance, etc. Conclusion: It gives out the distance decoding method and explores the method of capturing echo signal, which can fast and accurately calculate the distance and azimuth information of scanning.

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Liu, Wen-Jie, Yu-Ting Bai, Xue-Bo Jin, Ting-Li Su et Jian-Lei Kong. « Adaptive Broad Echo State Network for Nonstationary Time Series Forecasting ». Mathematics 10, n^o 17 (3 septembre 2022) : 3188. http://dx.doi.org/10.3390/math10173188.

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Time series forecasting provides a vital basis for the control and management of various systems. The time series data in the real world are usually strongly nonstationary and nonlinear, which increases the difficulty of reliable forecasting. To fully utilize the learning capability of machine learning in time series forecasting, an adaptive broad echo state network (ABESN) is proposed in this paper. Firstly, the broad learning system (BLS) is used as a framework, and the reservoir pools in the echo state network (ESN) are introduced to form the broad echo state network (BESN). Secondly, for the problem of information redundancy in the reservoir structure in BESN, an adaptive optimization algorithm for the BESN structure based on the pruning algorithm is proposed. Thirdly, an adaptive optimization algorithm of hyperparameters based on the nonstationary test index is proposed. In brief, the structure and hyperparameter optimization algorithms are studied to form the ABESN based on the proposed BESN model in this paper. The ABESN is applied to the data forecasting of air humidity and electric load. The experiments show that the proposed ABESN has a better learning ability for nonstationary time series data and can achieve higher forecasting accuracy.

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Li, Guangming, Jingye Yan et Ailan Lan. « An Improved Meteor Echo Recognition Algorithm for SuperDARN HF Radar ». Electronics 10, n^o 16 (16 août 2021) : 1971. http://dx.doi.org/10.3390/electronics10161971.

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The SuperDARN HF radars can be used for meteor observation and inversion of mid-upper atmosphere neutral wind using observed meteor echo Doppler velocities. Aiming at the problem that the extraction of meteor echo based on echo power, Doppler velocity and spectral width is rough and contains ionospheric echo, this paper optimizes the extraction algorithm of meteor echo. Based on the AgileDARN HF radar’s digital characteristics, the observation method of meteor echo was improved, and we designed a meteor observation mode without changing the hardware system: using a meteor observation with a 7.5 km range resolution and a 2 s integration time, we extracted the Doppler characteristics of different echo types at meteor echo ranges; according to these features, the extraction algorithm of meteor echo was optimized. By analyzing the measured data, the characteristics of diurnal variation, power distribution, Doppler velocity distribution and spectral width distribution of meteor echo extracted by the optimization algorithm were obtained. The meteor echo characteristics obtained by the improved algorithm are more consistent with the theoretical analysis; thus, the improved algorithm is better than the SuperDARN high frequency radar meteor echo extraction algorithm and has good performance. The meteor echo extraction algorithm presented in this paper can extract the meteor echo more accurately, so that the atmospheric neutral wind can be retrieved more accurately. At the same time, the proposed algorithm is not only applicable to AgileDARN HF radar meteor observation mode data, but also to AgileDARN and SuperDARN normal mode data, which is beneficial to expand the data application of SuperDARN radars.

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Lun, Shu-xian, Hai-feng Hu et Xian-shuang Yao. « The modified sufficient conditions for echo state property and parameter optimization of leaky integrator echo state network ». Applied Soft Computing 77 (avril 2019) : 750–60. http://dx.doi.org/10.1016/j.asoc.2019.02.005.

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Pedrycz, Adam, Henri-Pierre Valero, Hiroshi Hori, Kojiro Nishimiya, Hitoshi Sugiyama et Yoshino Sakata. « An ultrasonic echo characterization approach based on particle swarm optimization ». Journal of the Acoustical Society of America 136, n^o 4 (octobre 2014) : 2213. http://dx.doi.org/10.1121/1.4900032.

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Kimoto, Masanori, et Takuya Asami. « Multi-channel Acoustic Echo Canceler Based on Particle Swarm Optimization ». IEEJ Transactions on Electronics, Information and Systems 135, n^o 1 (2015) : 37–44. http://dx.doi.org/10.1541/ieejeiss.135.37.

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Amano, T., K. Tsuchiya, M. Kurita, S. Ooshimoda, Y. Kusakabe et K. Ito. « Optimization of multi shot Echo Planar Imaging of the abdomen. » Japanese Journal of Radiological Technology 53, n^o 1 (1997) : 190. http://dx.doi.org/10.6009/jjrt.kj00001355185.

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Chew, Jouh Yeong, Daisuke Kurabayashi et Yudai Nakamura. « Echo state networks with Tikhonov regularization : optimization using integral gain ». Advanced Robotics 29, n^o 12 (23 mars 2015) : 801–14. http://dx.doi.org/10.1080/01691864.2015.1010576.

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Epstein, Frederick H., et Andrew E. Arai. « Optimization of fast cardiac imaging using an echo-train readout ». Journal of Magnetic Resonance Imaging 11, n^o 2 (février 2000) : 75–80. http://dx.doi.org/10.1002/(sici)1522-2586(200002)11:2<75 ::aid-jmri1>3.0.co;2-p.

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Wallmeier, Ludwig, et Lutz Wiegrebe. « Self-motion facilitates echo-acoustic orientation in humans ». Royal Society Open Science 1, n^o 3 (novembre 2014) : 140185. http://dx.doi.org/10.1098/rsos.140185.

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The ability of blind humans to navigate complex environments through echolocation has received rapidly increasing scientific interest. However, technical limitations have precluded a formal quantification of the interplay between echolocation and self-motion. Here, we use a novel virtual echo-acoustic space technique to formally quantify the influence of self-motion on echo-acoustic orientation. We show that both the vestibular and proprioceptive components of self-motion contribute significantly to successful echo-acoustic orientation in humans: specifically, our results show that vestibular input induced by whole-body self-motion resolves orientation-dependent biases in echo-acoustic cues. Fast head motions, relative to the body, provide additional proprioceptive cues which allow subjects to effectively assess echo-acoustic space referenced against the body orientation. These psychophysical findings clearly demonstrate that human echolocation is well suited to drive precise locomotor adjustments. Our data shed new light on the sensory–motor interactions, and on possible optimization strategies underlying echolocation in humans.

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Zhang, Yu, Qiang Xing, Jiang-Hua Zhang, Wei-Feng Jiang, Mu Qin et Xu Liu. « Long-Term Effect of Different Optimizing Methods for Cardiac Resynchronization Therapy in Patients with Heart Failure : A Randomized and Controlled Pilot Study ». Cardiology 142, n^o 3 (2019) : 158–66. http://dx.doi.org/10.1159/000499502.

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Aim: During cardiac resynchronization therapy (CRT), optimized programming of the atrioventricular (AV) delay and ventricular-to-ventricular (VV) interval can lead to improved hemodynamics, symptomatic response, and left ventricular systolic function. Currently, however, there is no recommendation for the best optimization method. This study aimed to compare the long-term clinical outcomes of 4 different CRT optimization methods. Methods: One hundred and twenty-four consecutive CRT patients with severe heart failure and left bundle-branch block configuration were randomly assigned into four groups to undergo AV/VV delay optimization through echocardiogram (ECHO; n = 30), electrocardiogram (ECG; n = 32), QuickOpt algorithm (n = 28), and nominal AV/VV (n = 36) groups. Patients were followed up and underwent examinations, including New York Heart Association (NYHA) cardiac functional classification, 6-min walking distance (6MWD), and echocardiography, at 6, 12, 24, 36, and 48 months, respectively. The patients’ survival and clinical outcomes were compared among the four groups. Results: Kaplan-Meier survival analyses showed that the median survival was the same in the 4 groups: ECHO, 43 months; ECG, 44 months; QuickOpt, 44 months, and nominal, 41 months. At the 6-month follow-up, the reduction in left ventricular end diastolic diameter (LVEDD) was significantly less in the nominal group (–1.91 ± 2.58 mm) than that in the other three groups (ECHO: –3.70 ± 2.78 mm, p = 0.012; ECG: –3.53 ± 3.14 mm, p = 0.020; QuickOpt: –3.46 ± 2.65 mm, p = 0.032); 6MWD was significantly shorter in the nominal group (87.88 ± 34.76 m) than that in the other three groups (ECHO: 120.63 ± 56.93 m, p = 0.006; ECG: 114.97 ± 54.95 m, p = 0.020; QuickOpt: 114.57 ± 35.41 m, p = 0.027). Left ventricular ejection fraction (LVEF) significantly increased in ECHO (7.23 ± 2.76%, p = 0.010), ECG (8.50 ± 3.17%, p < 0.001), and QuickOpt (8.39 ± 2.90%, p < 0.001) compared with the nominal group (5.35 ± 2.59%). There were no significant differences among the groups in the aforementioned parameters at 24, 36, and 48 months, respectively. Conclusion: While LVEDD, LVEF, 6MWD, and NYHA were significantly improved in ECHO, ECG, and QuickOpt at 6 months, there were no significant improvements in any of the groups at 12, 24, and 48 months. These findings suggested that the long-term effect of the four CRT methods for heart failure was not significantly different.

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Liu, Z., X. Gao, G. Li et J. Chen. « DECOMPOSITION TECHNIQUES FOR ICESAT/GLAS FULL-WAVEFORM DATA ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3 (30 avril 2018) : 1179–82. http://dx.doi.org/10.5194/isprs-archives-xlii-3-1179-2018.

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The geoscience laser altimeter system (GLAS) on the board Ice, Cloud, and land Elevation Satellite (ICESat), is the first long-duration space borne full-waveform LiDAR for measuring the topography of the ice shelf and temporal variation, cloud and atmospheric characteristics. In order to extract the characteristic parameters of the waveform, the key step is to process the full waveform data. In this paper, the modified waveform decomposition method is proposed to extract the echo components from full-waveform. First, the initial parameter estimation is implemented through data preprocessing and waveform detection. Next, the waveform fitting is demonstrated using the Levenberg-Marquard (LM) optimization method. The results show that the modified waveform decomposition method can effectively extract the overlapped echo components and missing echo components compared with the results from GLA14 product. The echo components can also be extracted from the complex waveforms.

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Nelasov, N. J., R. V. Sidorov, M. N. Morgunov, N. S. Doltmurzieva, O. L. Eroshenko, E. A. Arzumanjan, A. G. Nechaeva et S. V. Shluik. « Echocardiographic Stress Test with Adenosine Triphosphate : Optimization of the Algorithm ». Kardiologiia 59, n^o 11 (15 décembre 2019) : 39–47. http://dx.doi.org/10.18087/cardio.2019.11.2665.

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Purpose. To: 1) optimize algorithm of stress echocardiography (s-Echo) with intravenous adenosine triphosphate (ATP) infusion taking into account pharmacokinetics and pharmacodynamics of ATP in human body, 2) test new algorithm in patients with coronary and other heart diseases. Materials and methods. In order to determine spectrum of factors influencing the results of stress test with ATP we inspected main scientific data bases and found 48 publications on ATP application for diagnostic purposes. Analysis of these publications allowed us to optimize algorithm of ATP s-Echo. Optimized algorithm was tested on 26 subjects, who underwent ATP 4D strain-stress-echocardiography of the left ventricle. Results and discussion. Optimized algorithm has three stages: registration of Echo data sets before, at the time of ATP infusion, and after 5 min of ATP infusion termination. Registration of Echo parameters at the second stage must begin not earlier than 3 min after the onset of ATP infusion and only in the presence of signs of coronary vasodilation. We think that the main indirect criterion of submaximal coronary vasodilation is 5 mm Hg or more decrease in systolic blood pressure (SBP), but not below SBP level of 90 mm Hg. Initial dose of ATP is 140 µg/kg/min. If after 2 min of infusion SBP do not diminish we increase the infusion rate at first to 175 and then to 210 µg/kg/min. While testing new algorithm in all cases we have achieved criteria of effective vasodilation. Mean SBP decrease was 16.4±13.7 mm Hg, heart rate increase – 12.7±8.1 bpm. In all patients we obtained interpretable 4D LV Echo data sets for visual analysis of local contractility and automatic strain analysis. Conclusion. Optimization of ATP sEcho algorithm was performed. Safety and efficacy of optimized algorythm for registration of echo data was demonstrated. New ATP infusion algorithm can also be recommended for testing with other cardiac imaging modalities in evaluation of myocardial perfusion and contractility (SPECT, CT, MRI, PET).

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Alger, Jeffry R., Julie H. Harreld, Sloane Chen, Jan Mintorovitch et David S. K. Lu. « Time-to-echo optimization for spin echo magnetic resonance imaging of liver metastasis using superparamagnetic iron oxide particles ». Journal of Magnetic Resonance Imaging 14, n^o 5 (2001) : 586–94. http://dx.doi.org/10.1002/jmri.1223.

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Wang Jiaojiao, 王姣姣, 王欣 Wang Xin, 高彦泽 Gao Yanze, 李卓 Li Zhuo, 杨苏辉 Yang Suhui et 张金英 Zhang Jinying. « 基于相似度评估的激光雷达回波场景生成优化 ». Acta Optica Sinica 41, n^o 20 (2021) : 2028001. http://dx.doi.org/10.3788/aos202141.2028001.

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Tenenbaum, R. A., L. T. Stutz et K. M. Fernandes. « Damage Identification in Bars with a Wave Propagation Approach : Performance Comparison of Five Hybrid Optimization Methods ». Shock and Vibration 20, n^o 5 (2013) : 863–78. http://dx.doi.org/10.1155/2013/467590.

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The formulation and solution of the inverse problem of damage identification based on an one-dimensional wave propagation approach are presented in this paper. Time history responses, obtained from pulse-echo synthetic experiments, are used to damage identification. The identification process is built on the minimization of the squared residue between the synthetic experimental echo, obtained by using a sequential algebraic algorithm, and the corresponding analytical one. Five different hybrid optimization methods are investigated. The hybridization is performed combining the deterministic Levenberg-Marquardt method and each one of the following stochastic techniques: The Particle Swarm Optimization; the Luus-Jaakola optimization method; the Simulated Annealing method; the Particle Collision method; and a Genetic Algorithm. A performance comparison of the five hybrid techniques is presented. Different damage scenarios are considered and, in order to account for noise corrupted data, signals with 10 dB of signal to noise ratio are also considered. It is shown that the damage identification procedure built on the Sequential Algebraic Algorithm yielded to very fast and successful solutions. In the performance comparison, it is also shown that the hybrid technique combining the Luus-Jaakola and the Levenberg-Marquardt optimization methods provides the faster damage recovery.

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Fang, Hong Yuan, Jian Li, Yue Meng Wang et Jia Li. « Inverse Analysis of Pavement Thickness Based on Improved Particle Swarm Optimization ». Advanced Materials Research 850-851 (décembre 2013) : 813–16. http://dx.doi.org/10.4028/www.scientific.net/amr.850-851.813.

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Core-drilling is the traditional pavement thickness detection method. However, this way is low efficient and destructive. The Ground Penetrating Radar (GPR) is a continuous, high efficient, non-destructive pavement quality testing tool. The dielectric constant, thickness and other information of pavement structure layer are obtained by inverse analysis of GPR echo signal. In this paper, the improved Particle Swarm Optimization (IPSO) is developed to analyze the dielectric constant and thickness of the pavement structure. Compared with inverse analysis results of theoretical model, the inverse precision of IPSO is higher than that of PSO. In addition, the measured echo signal of GPR is analyzed by the IPSO. The errors between inverse results and the actual core-drilling measurements are less than 3%.

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Yin, Zhiping, Xinfei Lu et Weidong Chen. « Echo Preprocessing to Enhance SNR for 2D CS-Based ISAR Imaging Method ». Sensors 18, n^o 12 (13 décembre 2018) : 4409. http://dx.doi.org/10.3390/s18124409.

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A new CS-based inverse synthetic aperture radar (ISAR) imaging framework is proposed to enhance both the image performance and the robustness at a low SNR. An ISAR echo preprocessing method for enhancing the ISAR imaging quality of compressed sensing (CS) based algorithms is developed by implementing matched filtering, echo denoising and matrix optimization sequentially. After the preprocessing, the two-dimensional (2D) SL0 algorithm is applied to reconstruct an ISAR image in the range and cross-range plane through a series of 2D matrices using the 2D CS theory, rather than converting the 2D convex optimization problem to the one-dimensional (1D) problem in the image reconstruction process. The proposed preprocessing framework is verified by simulations and experiment. Simulations and experimental results show that the ISAR image obtained by the 2D sparse recovery algorithm with our proposed method has a better performance.

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Huang, Chuan, Zhongyu Li, Mingyue Lou, Xingye Qiu, Hongyang An, Junjie Wu, Jianyu Yang et Wei Huang. « BeiDou-Based Passive Radar Vessel Target Detection : Method and Experiment via Long-Time Optimized Integration ». Remote Sensing 13, n^o 19 (30 septembre 2021) : 3933. http://dx.doi.org/10.3390/rs13193933.

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The BeiDou navigation satellite system shows its potential for passive radar vessel target detection owing to its global-scale coverage. However, the restrained power budget from BeiDou satellite hampers the detection performance. To solve this limitation, this paper proposes a long-time optimized integration method to obtain an adequate signal-to-noise ratio (SNR). During the long observation time, the range migration, intricate Doppler migration, and noncoherence characteristic bring challenges to the integration processing. In this paper, first, the keystone transform is applied to correct the range walk. Then, considering the noncoherence of the entire echo, the hybrid integration strategy is adopted. To remove the Doppler migration and correct the residual range migration, the long-time integration is modeled as an optimization problem. Finally, the particle swarm optimization (PSO) algorithm is applied to solve the optimization problem, after which the target echo over the long observation time is well concentrated, providing a reliable detection performance for the BeiDou-based passive radar. Its effectiveness is shown by the simulated and experimental results.

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Haitao Jia, Wei Zhang, Mei Xie, Ke Zhang et Xixu He. « Based on Target Echo Model Netted Radar Coverage Fusion Performance Optimization ». International Journal of Digital Content Technology and its Applications 7, n^o 5 (15 mars 2013) : 424–33. http://dx.doi.org/10.4156/jdcta.vol7.issue5.51.

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Jaeger, Herbert, Mantas Lukoševičius, Dan Popovici et Udo Siewert. « Optimization and applications of echo state networks with leaky- integrator neurons ». Neural Networks 20, n^o 3 (avril 2007) : 335–52. http://dx.doi.org/10.1016/j.neunet.2007.04.016.

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Duan, Haibin, et Xiaohua Wang. « Echo State Networks With Orthogonal Pigeon-Inspired Optimization for Image Restoration ». IEEE Transactions on Neural Networks and Learning Systems 27, n^o 11 (novembre 2016) : 2413–25. http://dx.doi.org/10.1109/tnnls.2015.2479117.

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Chan, Kimberly L., Nicolaas A. J. Puts, Karim Snoussi, Ashley D. Harris, Peter B. Barker et Richard A. E. Edden. « Echo time optimization for J-difference editing of glutathione at 3T ». Magnetic Resonance in Medicine 77, n^o 2 (25 février 2016) : 498–504. http://dx.doi.org/10.1002/mrm.26122.

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Shrestha, Manoj, Pavel Hok, Ulrike Nöth, Bianca Lienerth et Ralf Deichmann. « Optimization of diffusion-weighted single-refocused spin-echo EPI by reducing eddy-current artifacts and shortening the echo time ». Magnetic Resonance Materials in Physics, Biology and Medicine 31, n^o 5 (30 mars 2018) : 585–97. http://dx.doi.org/10.1007/s10334-018-0684-x.

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Kirillova, V. V. « Echocardiography features in determining left atrial dilatation in patients with hypertension ». Translational Medicine 8, n^o 3 (18 juillet 2021) : 5–13. http://dx.doi.org/10.18705/2311-4495-2021-8-3-5-13.

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Background. The correct echocardiographic (Echo) determination of left atrial (LA) dilatation is a criterion for diagnosing heart failure with the preserved ejection fraction.Objective. The aim is to detect probable reasons for underestimating the LA area by Echo in hypertension patients.Design and methods. In the prospective study, the LA area was measured echocardiographically in 89 ambulatory patients (P-wave duration in standard lead II was > 0.1 mm in 57 patients and ≤ 0.1 mm in 32 patients) from the apical four- and two-chamber views with and without focusing on the LA, and from the subcostal four-chamber view.Results. A strong positive correlation was detected between ECG P-wave duration and the Echo LA area (r = 0.74). The LA areas were revealed to be different in patients with P-wave duration over 0.1 mm from the apical fourchamber view with optimization of displaying the LA (22.33 ± 0.68 and 19.02 ± 0.56 cm2, respectively). The maximum LA area was detected from the subcostal fourchamber view (24.41 ± 0.78).Conclusion. Thus, using the correspondence between the LA area and Pwave duration in standard lead II, optimization of displaying the LA, and additionally measuring the LA dimensions from the subcostal view, sonologists can avoid underestimating LA dimensions.

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Cheng, Guoliang, Lele Liao, Kai Chen, Yuxiang Hu, Changbao Zhu et Jing Lu. « Semi-blind source separation using convolutive transfer function for nonlinear acoustic echo cancellation ». Journal of the Acoustical Society of America 153, n^o 1 (janvier 2023) : 88–95. http://dx.doi.org/10.1121/10.0016823.

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The recently proposed semi-blind source separation (SBSS) method for nonlinear acoustic echo cancellation (NAEC) outperforms adaptive NAEC in attenuating the nonlinear acoustic echo. However, the multiplicative transfer function (MTF) approximation makes it unsuitable for real-time applications, especially in highly reverberant environments, and the natural gradient makes it hard to balance well between fast convergence speed and stability. In this paper, two more effective SBSS methods based on auxiliary-function-based independent vector analysis (AuxIVA) and independent low-rank matrix analysis (ILRMA) are proposed. The convolutive transfer function approximation is used instead of the MTF so that a long impulse response can be modeled with a short latency. The optimization schemes used in AuxIVA and ILRMA are carefully regularized according to the constrained demixing matrix of NAEC. The experimental results validate significantly better echo cancellation performances of the proposed methods.

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Li, Yi Ning, Pei Lin Zhang, Chao Xu, Yun Qiang Zhang et Long Yun Li. « An Improved Online De-Noising Method for Ultrasonic Echo Signal of Wear Debris in Oil ». Applied Mechanics and Materials 631-632 (septembre 2014) : 490–93. http://dx.doi.org/10.4028/www.scientific.net/amm.631-632.490.

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The ultrasonic echo signal of wear debris is influenced by many matters. It causes so much more noise. Therefore, it puts forward an improved online de-noising method for ultrasonic echo signal of wear debris in oil. In the dual-tree complex wavelet transform (DTCWT) field, a method, which combines the new non-linear threshold function with adaptive threshold, utilizes particle swarm optimization (PSO) for optimizing the parameter of non-linear threshold function to get the optimal solution. The result of de-noising method can be evaluated. Experimental results show that the proposed method has obvious effect on signal de-noising.

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Anisimov, N. V., M. V. Gulyaev, D. V. Volkov, S. S. Batova, O. S. Pavlova, D. V. Fomina et Yu A. Pirogov. « Optimization of MRI parameters for the gradient echo method in fluorocarbon research ». Physics of Wave Phenomena 25, n^o 2 (avril 2017) : 140–46. http://dx.doi.org/10.3103/s1541308x1702011x.

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Racca, Alberto, et Luca Magri. « Robust Optimization and Validation of Echo State Networks for learning chaotic dynamics ». Neural Networks 142 (octobre 2021) : 252–68. http://dx.doi.org/10.1016/j.neunet.2021.05.004.

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Hathout, Gasser, et Neema Jamshidi. « Parameter Optimization for Quantitative Signal-Concentration Mapping Using Spoiled Gradient Echo MRI ». Radiology Research and Practice 2012 (2012) : 1–9. http://dx.doi.org/10.1155/2012/815729.

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Rationale and Objectives. Accurate signal to tracer concentration maps are critical to quantitative MRI. The purpose of this study was to evaluate and optimize spoiled gradient echo (SPGR) MR sequences for the use of gadolinium (Gd-DTPA) as a kinetic tracer.Methods. Water-gadolinium phantoms were constructed for a physiologic range of gadolinium concentrations. Observed and calculated SPGR signal to concentration curves were generated. Using a percentage error determination, optimal pulse parameters for signal to concentration mapping were obtained.Results. The accuracy of the SPGR equation is a function of the chosen MR pulse parameters, particularly the time to repetition (TR) and the flip angle (FA). At all experimental values of TR, increasing FA decreases the ratio between observed and calculated signals. Conversely, for a constant FA, increasing TR increases this ratio. Using optimized pulse parameter sets, it is possible to achieve excellent accuracy (approximately 5%) over a physiologic range of concentration tracer concentrations.Conclusion. Optimal pulse parameter sets exist and their use is essential for deriving accurate signal to concentration curves in quantitative MRI.

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Deene, Y. De, et C. Baldock. « Optimization of multiple spin$ndash$echo sequences for 3D polymer gel dosimetry ». Physics in Medicine and Biology 47, n^o 17 (6 août 2002) : 3117–41. http://dx.doi.org/10.1088/0031-9155/47/17/306.

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Wang, Heshan, et Xuefeng Yan. « Optimizing the echo state network with a binary particle swarm optimization algorithm ». Knowledge-Based Systems 86 (septembre 2015) : 182–93. http://dx.doi.org/10.1016/j.knosys.2015.06.003.

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