Journal articles: 'Global attenuation'

1

Dalton, Colleen A., and Göran Ekström. "Global models of surface wave attenuation." Journal of Geophysical Research: Solid Earth 111, B5 (May 2006): n/a. http://dx.doi.org/10.1029/2005jb003997.

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Shiuly, Amit. "Global Attenuation Relationship for Estimating Peak Ground Acceleration." Journal of the Geological Society of India 92, no. 1 (July 2018): 54–58. http://dx.doi.org/10.1007/s12594-018-0952-4.

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Paz, Maria Catarina, Francisco J. Alcalá, and Luís Ribeiro. "Ground Penetrating Radar Attenuation Expressions in Shallow Groundwater Research." Journal of Environmental and Engineering Geophysics 25, no. 1 (March 2020): 153–60. http://dx.doi.org/10.2113/jeeg19-039.

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The electromagnetic-wave attenuation coefficient determines the overall resolution and effective penetration depth of ground penetrating radar (GPR) surveys. Despite this relevance to the design of proper GPR surveys, the attenuation expressions are rarely used in the applied shallow groundwater research (SGR) literature. This work examines the status of the attenuation expressions in SGR. For this, 73 GPR case studies (in 47 papers), including some information concerning the attenuation variables and parameters, were selected to build a database. From these, 18 cases (in 10 papers) provided attenuation expressions and only 11 cases (in 4 papers) used those expressions. Two types of expressions were identified, physically based global ones that try to solve a broad (but not complete) range of environmental and field technical conditions, and non-global ones adapted for specific geological environments and resolution needed. The database analysis showed that both global and non-global expressions were used exclusively in low-loss media to report an attenuation range of 0.1–21.5 dB m −1 by using common antenna frequencies in the 25–900 MHz range. The range of the attenuation expressions validity in SGR is biased because no surveys in variable-loss heterogeneous media and wider antenna frequency intervals could be compiled. The attenuation database generated seeks to improve the design of GPR surveys in SGR.

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Graizer, Vladimir, Erol Kalkan, and Kuo-Wan Lin. "Global Ground Motion Prediction Equation for Shallow Crustal Regions." Earthquake Spectra 29, no. 3 (August 2013): 777–91. http://dx.doi.org/10.1193/1.4000140.

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The Graizer-Kalkan ground-motion prediction equation (GMPE) for peak ground acceleration (PGA) constitutes a series of filters, each of which represents a certain physical phenomenon affecting the radiation of seismic waves from the source. The performance of this GMPE is examined by using about 14,000 records from 245 worldwide shallow crustal events. The recorded data and predictions show an excellent match as far as 100 km from the fault. Beyond 100 km, the data generally show faster attenuation on the order of Rrup−4 due to a relatively low Q (as in the western United States) or slower attenuation on the order of Rrup−1.5 due to a high Q (as in the central and eastern United States). An improved GMPE is developed to account for regional variations in ground motion attenuation. The The new GMPE produces a better match to recorded data up to 500 km from the fault.

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Jiang, Zhong-Ping. "Nonlinear disturbance attenuation with global stability via output feedback." IFAC Proceedings Volumes 32, no. 2 (July 1999): 2440–45. http://dx.doi.org/10.1016/s1474-6670(17)56415-0.

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Berger, G., P. Laugier, J. C. Thalabard, and J. Perrin. "Global Breast Attenuation: Control Group and Benign Breast Diseases." Ultrasonic Imaging 12, no. 1 (January 1990): 47–57. http://dx.doi.org/10.1177/016173469001200104.

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This paper deals with the estimation of the slope of attenuation in human breast tissue. The measurement is done in the reflection mode with a short time Fourier analysis. All important factors such as diffraction effect, tissue depth and specular reflectors are taken into account. A population of 49 normal women shows large inter-individual variations of the attenuation coefficient. A multiple linear regression allows correlation of this variation with the duration of the woman's genital life and pregnancies. A preliminary study is done on 10 benign diffuse breast diseases and shows a weak correlation with the type of the breast: normal or pathological. The utility of the quantification is discussed for one case of large fibrocystic disease.

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Chandrasekar, V., H. Fukatsu, and K. Mubarak. "Global mapping of attenuation at ku- and ka-band." IEEE Transactions on Geoscience and Remote Sensing 41, no. 10 (October 2003): 2166–76. http://dx.doi.org/10.1109/tgrs.2003.815973.

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Berger, G. "Global breast attenuation: Control group and benign breast diseases." Ultrasonic Imaging 12, no. 1 (January 1990): 47–57. http://dx.doi.org/10.1016/0161-7346(90)90220-r.

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9

Vafeidis, Athanasios T., Mark Schuerch, Claudia Wolff, Tom Spencer, Jan L. Merkens, Jochen Hinkel, Daniel Lincke, Sally Brown, and Robert J. Nicholls. "Water-level attenuation in global-scale assessments of exposure to coastal flooding: a sensitivity analysis." Natural Hazards and Earth System Sciences 19, no. 5 (May 3, 2019): 973–84. http://dx.doi.org/10.5194/nhess-19-973-2019.

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Abstract. This study explores the uncertainty introduced in global assessments of coastal flood exposure and risk when not accounting for water-level attenuation due to land-surface characteristics. We implement a range of plausible water-level attenuation values for characteristic land-cover classes in the flood module of the Dynamic and Integrated Vulnerability Assessment (DIVA) modelling framework and assess the sensitivity of flood exposure and flood risk indicators to differences in attenuation rates. Results show a reduction of up to 44 % in area exposure and even larger reductions in population exposure and expected flood damages when considering water-level attenuation. The reductions vary by country, reflecting the differences in the physical characteristics of the floodplain as well as in the spatial distribution of people and assets in coastal regions. We find that uncertainties related to not accounting for water attenuation in global assessments of flood risk are of similar magnitude to the uncertainties related to the amount of sea-level rise expected over the 21st century. Despite using simplified assumptions to account for the process of water-level attenuation, which depends on numerous factors and their complex interactions, our results strongly suggest that an improved understanding and representation of the temporal and spatial variation of water levels across floodplains is essential for future impact modelling.

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Lam, Bhan, Dongyuan Shi, Valiantsin Belyi, Shulin Wen, Woon-Seng Gan, Kelvin Li, and Irene Lee. "Active Control of Low-Frequency Noise through a Single Top-Hung Window in a Full-Sized Room." Applied Sciences 10, no. 19 (September 29, 2020): 6817. http://dx.doi.org/10.3390/app10196817.

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The push for greater urban sustainability has increased the urgency of the search for noise mitigation solutions that allow for natural ventilation into buildings. Although a viable active noise control (ANC) solution with up to 10 dB of global attenuation between 100 Hz and 1000 Hz was previously developed for an open window, it had limited low-frequency performance below 300 Hz, owing to the small loudspeakers used. To improve the low-frequency attenuation, four passive radiator-based speakers were affixed around the opening of a top-hung ventilation window. The active control performance between 100 Hz and 700 Hz on a single top-hung window in a full-sized mock-up apartment room was examined. Active attenuation came close to the performance of the passive insulation provided by fully closing the window for expressway traffic and motorbike passing noise types. For a jet aircraft flyby, the performance of active attenuation with the window fully opened was similar to that of passive insulation with fully closed windows. In the case of low-frequency compressor noise, active attenuation’s performance was significantly better than the passive insulation. Overall, between 8 dB and 12 dB of active attenuation was achieved directly in front of the window opening, and up to 10.5 dB of attenuation was achieved across the entire room.

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11

Smolders, S., Y. Plancke, S. Ides, P. Meire, and S. Temmerman. "Role of intertidal wetlands for tidal and storm tide attenuation along a confined estuary: a model study." Natural Hazards and Earth System Sciences 15, no. 7 (July 30, 2015): 1659–75. http://dx.doi.org/10.5194/nhess-15-1659-2015.

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Abstract. Coastal lowlands and estuaries are subjected to increasing flood risks during storm surges due to global and regional changes. Tidal wetlands are increasingly valued as effective natural buffers for storm surges by dissipating wave energy and providing flood water storage. While previous studies focused on flood wave attenuation within and behind wetlands, this study focuses on the effects of estuarine wetland properties on the attenuation of a storm tide that propagates along the length of an estuary. Wetland properties including elevation, surface area, and location within the estuary were investigated using a numerical model of the Scheldt estuary (Belgium, SW Netherlands). For a spring tide lower wetland elevations result in more attenuation of high water levels along the estuary, while for a higher storm tide higher elevations provide more attenuation compared to lower wetland elevations. For spring and storm tide a larger wetland surface area results in a better attenuation along the estuary up to a threshold wetland size for which larger wetlands do not further contribute to more attenuation. Finally a wetland of the same size and elevation, but located more upstream in the estuary, can store a larger proportion of the local flood volume and therefore has a larger attenuating effect on upstream high water levels. With this paper we aim to contribute towards a better understanding and wider implementation of ecosystem-based adaptation to increasing estuarine flood risks associated with storms.

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Smolders, S., Y. Plancke, S. Ides, P. Meire, and S. Temmerman. "Role of intertidal wetlands for tidal and storm tide attenuation along a confined estuary: a model study." Natural Hazards and Earth System Sciences Discussions 3, no. 5 (May 8, 2015): 3181–224. http://dx.doi.org/10.5194/nhessd-3-3181-2015.

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Abstract. Coastal lowlands and estuaries are subjected to increasing flood risks during storm surges due to global and regional changes. Tidal wetlands are increasingly valued as effective natural buffers for storm surges by dissipating wave energy and providing flood water storage. While previous studies focused on flood wave attenuation within and behind wetlands, this study focuses on the effects of estuarine wetland properties on the attenuation of a storm tide that propagates along the length of an estuary. Wetland properties including elevation, surface area, and location within the estuary were investigated using a numerical model of the Scheldt estuary (Belgium, SW Netherlands). For a spring tide lower wetland elevations result in more attenuation of high water levels along the estuary, while for a higher storm tide higher elevations provide more attenuation compared to lower wetland elevations. For spring and storm tide a arger wetland surface area results in a better attenuation along the estuary up to a threshold wetland size for which larger wetlands do not further contribute to more attenuation. Finally a wetland of the same size and elevation, but located more upstream in the estuary, can store a larger proportion of the local flood volume and therefore has a larger attenuating effect on upstream high water levels. With this paper we aim to contribute towards a better understanding and wider implementation of ecosystem-based adaptation to increasing estuarine flood risks associated with storms.

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13

Kourkchi, Ehsan, R. Brent Tully, J. Don Neill, Mark Seibert, Hélène M. Courtois, and Alexandra Dupuy. "Global Attenuation in Spiral Galaxies in Optical and Infrared Bands." Astrophysical Journal 884, no. 1 (October 14, 2019): 82. http://dx.doi.org/10.3847/1538-4357/ab4192.

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14

Padhy, Simanchal. "A scattering model for seismic attenuation and its global applications." Physics of the Earth and Planetary Interiors 148, no. 1 (January 2005): 1–12. http://dx.doi.org/10.1016/j.pepi.2004.05.010.

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15

Xu, Jiangtao, Feng Li, Liqiang Han, Zhiyuan Gao, and Han Wang. "Analysis of signal attenuation in global shutter CMOS image sensor." Microelectronics Reliability 109 (June 2020): 113678. http://dx.doi.org/10.1016/j.microrel.2020.113678.

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16

David Johnson, J. "Noradrenergic control of cognition: global attenuation and an interrupt function." Medical Hypotheses 60, no. 5 (May 2003): 689–92. http://dx.doi.org/10.1016/s0306-9877(03)00021-5.

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17

Park, Young C., and Scott D. Sommerfeldt. "Global attenuation of broadband noise fields using energy density control." Journal of the Acoustical Society of America 101, no. 1 (January 1997): 350–59. http://dx.doi.org/10.1121/1.417980.

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18

Su, Weizhou, Lihua Xie, Carlos E. de Souza, and Zhiming Gong. "Global Robust Disturbance Attenuation for Uncertain Minimum Phase Nonlinear Systems." IFAC Proceedings Volumes 30, no. 16 (June 1997): 315–20. http://dx.doi.org/10.1016/s1474-6670(17)42625-5.

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19

Lin, Junfang, Zhongping Lee, Michael Ondrusek, and Mati Kahru. "Attenuation coefficient of usable solar radiation of the global oceans." Journal of Geophysical Research: Oceans 121, no. 5 (May 2016): 3228–36. http://dx.doi.org/10.1002/2015jc011528.

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20

Veal, Cameron J., Kelvin J. Michael, and Manuel Nunez. "Partitioning of underwater direct and diffuse ultraviolet irradiance in a shallow water coral reef." Marine and Freshwater Research 60, no. 12 (2009): 1244. http://dx.doi.org/10.1071/mf08318.

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In optically shallow waters of coral reefs, the contribution of both direct and diffuse ultraviolet irradiance is poorly documented yet its involvement in biological processes is highly significant. Here we present a new approach of partitioning the ultraviolet attenuation coefficient into direct and diffuse components in the top 5 m of waters surrounding Heron Reef, Queensland, Australia (23°27′S, 151°55′E), during the austral summer solstice from 11 to 21 December 2005. A commercial ultraviolet radiometer, which operated in selected spectral bands centred at 305, 313, 320, 340, 380 and 395 nm, was fitted with an aquatic shadow-band that allowed the measurement of both global and diffuse irradiances. Direct irradiance was estimated by subtracting diffuse irradiance from global irradiance. Results revealed that direct irradiance was attenuated more quickly than diffuse irradiance, with stronger attenuation in the shorter wavelengths. Attenuation coefficients for the global, diffuse and direct components of irradiance were significantly different, justifying their separate treatment through partitioning. A significant dependence on turbidity explained more than 70% of the variation in attenuation of ultraviolet irradiance at the shorter wavelengths. The direct ultraviolet irradiance can exceed 50% of the global ultraviolet irradiance in shallow waters (0–5 m), a significant result that is generally overlooked in optical and biological studies.

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21

Font, Carme, Francesco Bregoli, Vicenç Acuña, Sergi Sabater, and Rafael Marcé. "GLOBAL-FATE (version 1.0.0): A geographical information system (GIS)-based model for assessing contaminants fate in the global river network." Geoscientific Model Development 12, no. 12 (December 11, 2019): 5213–28. http://dx.doi.org/10.5194/gmd-12-5213-2019.

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Abstract. GLOBAL-FATE is the first open-source, multiplatform, user-friendly, and modular contaminant-fate model operating at the global scale linking human consumption of pharmaceutical-like compounds with their concentration in the river network. GLOBAL-FATE simulates human consumption and excretion of pharmaceuticals, the attenuation of the contaminant load in waste water treatment plants as well as the attenuation of the contaminant load in river reaches, lakes, and reservoirs as a first-order decay depending on residence time. We provide a comprehensive description of model equations and the overall structure of the model, with special attention to input–output datasets. GLOBAL-FATE is written in C, can be compiled in any platform, and uses inputs in standard geographical information system (GIS) format. Additionally, the model can be run in the Quantum Geographic Information System (QGIS) as a plug-in. The model has no built-in working resolution, which depends on the intended use and the availability of appropriate model inputs and observed data. We exemplify the application of GLOBAL-FATE solving the global concentration of diclofenac in the river network. A comparison with a dataset of diclofenac concentration observations in rivers suggests that GLOBAL-FATE can be successfully applied in real-case modelling exercises. The model is particularly sensitive to the generation of contaminant loads by human pharmaceutical consumption and to the processes governing contaminant attenuation in the river network. GLOBAL-FATE will be a valuable tool for the scientific community and the policymaking arena and could be used to test the effectiveness of large-scale management strategies related to pharmaceutical consumption control and waste water treatment implementation and upgrading.

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22

Rumsey, Clifton C., and L. F. Abbott. "Equalization of Synaptic Efficacy by Activity- and Timing-Dependent Synaptic Plasticity." Journal of Neurophysiology 91, no. 5 (May 2004): 2273–80. http://dx.doi.org/10.1152/jn.00900.2003.

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In many neurons, synapses increase in strength as a function of distance from the soma in a manner that appears to compensate for dendritic attenuation. This phenomenon requires a cooperative interaction between local factors that control synaptic strength, such as receptor density and vesicle release probability, and global factors that affect synaptic efficacy, such as attenuation and boosting by active membrane conductances. Anti-spiketiming-dependent plasticity, in combination with nonassociative synaptic potentiation, can accomplish this feat even though it acts locally and independently at individual synapses. Analytic computations and computer simulations show that this combination of synaptic plasticity mechanisms equalizes the efficacy of synapses over an extended dendritic cable by adjusting local synaptic strengths to compensate for global attenuation.

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23

Buat, Véronique, David Corre, Médéric Boquien, and Katarzyna Małek. "Which attenuation curves for star-forming galaxies?" Proceedings of the International Astronomical Union 15, S341 (November 2019): 70–73. http://dx.doi.org/10.1017/s1743921319002692.

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AbstractDust attenuation shapes the spectral energy distributions of galaxies and any modelling and fitting procedure of their spectral energy distributions must account for this process. We present results of two recent works dedicated at measuring the dust attenuation curves in star forming galaxies at redshift from 0.5 to 3, by fitting continuum (photometric) and line (spectroscopic) measurements simultaneously with CIGALE using variable attenuation laws based on flexible recipes. Both studies conclude to a large variety of effective attenuation laws with an attenuation law flattening when the obscuration increases. An extra attenuation is found for nebular lines. The comparison with radiative transfer models implies a flattening of the attenuation law up to near infrared wavelengths, which is well reproduced with a power-laws recipe inspired by the Charlot and Fall recipe. Here we propose a global modification of the Calzetti attenuation law to better reproduce the results of radiative transfer models.

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Jain, Atul, Xiaojuan Yang, Haroon Kheshgi, A. David McGuire, Wilfred Post, and David Kicklighter. "Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors." Global Biogeochemical Cycles 23, no. 4 (December 2009): n/a. http://dx.doi.org/10.1029/2009gb003519.

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25

Hutyra, John, Leonid Bunegin, Maurice S. Albin, and Karen Bernal. "ATTENUATION OF EFFECTS OF GLOBAL CEREBRAL ISCHEI'IA IN A CANINE MODEL." Anesthesiology 69, no. 3A (September 1, 1988): A588. http://dx.doi.org/10.1097/00000542-198809010-00588.

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26

Romanowicz, B. "A global tomographic model of shear attenuation in the upper mantle." Journal of Geophysical Research: Solid Earth 100, B7 (July 10, 1995): 12375–94. http://dx.doi.org/10.1029/95jb00957.

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27

Bhattacharyya, Joydeep, Guy Masters, and Peter Shearer. "Global lateral variations of shear wave attenuation in the upper mantle." Journal of Geophysical Research: Solid Earth 101, B10 (October 10, 1996): 22273–89. http://dx.doi.org/10.1029/96jb01782.

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28

Gangoda, L., M. Doerflinger, Y. Y. Lee, A. Rahimi, N. Etemadi, D. Chau, L. Milla, L. O'Connor, and H. Puthalakath. "Cre transgene results in global attenuation of the cAMP/PKA pathway." Cell Death & Disease 3, no. 8 (August 2012): e365-e365. http://dx.doi.org/10.1038/cddis.2012.110.

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29

Yang, Jun, Chuanlin Zhang, Shihua Li, and Xitong Niu. "Semi-Global Exquisite Disturbance Attenuation Control for Perturbed Uncertain Nonlinear Systems." Asian Journal of Control 19, no. 4 (February 6, 2017): 1608–19. http://dx.doi.org/10.1002/asjc.1475.

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30

D'Cruz, J. "GLOBAL ATTENUATION OF RANDOM VIBRATIONS IN A TAPERED AND SWEPT PANEL." Journal of Sound and Vibration 199, no. 5 (February 1997): 751–76. http://dx.doi.org/10.1006/jsvi.1996.0651.

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31

Tattersall, J. M., D. G. Browning, and R. F. Laplante. "Low‐frequency surface loss values obtained using the global attenuation model." Journal of the Acoustical Society of America 87, S1 (May 1990): S110. http://dx.doi.org/10.1121/1.2027836.

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32

Bao, Xueyang, Colleen A. Dalton, and Jeroen Ritsema. "Effects of elastic focusing on global models of Rayleigh wave attenuation." Geophysical Journal International 207, no. 2 (August 26, 2016): 1062–79. http://dx.doi.org/10.1093/gji/ggw322.

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33

Vindel, J. M., J. Polo, L. F. Zarzalejo, and L. Ramírez. "Stochastic model to describe atmospheric attenuation from yearly global solar irradiation." Atmospheric Research 153 (February 2015): 209–16. http://dx.doi.org/10.1016/j.atmosres.2014.08.013.

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34

Dalton, Colleen A., Göran Ekström, and Adam M. Dziewonski. "Global seismological shear velocity and attenuation: A comparison with experimental observations." Earth and Planetary Science Letters 284, no. 1-2 (June 2009): 65–75. http://dx.doi.org/10.1016/j.epsl.2009.04.009.

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35

Dalton, Colleen A., Xueyang Bao, and Zhitu Ma. "The thermal structure of cratonic lithosphere from global Rayleigh wave attenuation." Earth and Planetary Science Letters 457 (January 2017): 250–62. http://dx.doi.org/10.1016/j.epsl.2016.10.014.

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36

Song, Yongjia, Jun Wang, Hengshan Hu, and Bo Han. "Frequency-dependent anisotropy in porous rocks with aligned cracks containing compressible fluid–a model based on poroelastic spring condition and exact solution of scattering by a circular crack at oblique incidence." Geophysical Journal International 226, no. 2 (April 15, 2021): 1105–29. http://dx.doi.org/10.1093/gji/ggab145.

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SUMMARY Thorough understanding of seismic signatures in cracked rocks is essential to estimate rock physical properties. Wave-induced fluid flow (or diffusion), scattering and Biot's global flow are three major mechanisms in controlling frequency-dependent attenuation and dispersion. To shed light on how those mechanisms and their interference affect the anisotropic features in cracked porous rocks, we develop an analytic model to estimate the angle-dependent attenuation and dispersion in such media. The most noteworthy feature of the model is that it is developed upon the exact solution of the problem of elastic wave scattered by a crack at oblique incidence. In particular, the poroelastic spring condition is applied to describe the influences of crack thickness and crack-filling fluid elasticity on wave scattering. Regardless of its complexity, we have showed that the model agrees with many benchmark theories under corresponding conditions, demonstrating its reasonability. It is found that the key factors that dominate anisotropic attenuation and dispersion are different in separating frequency regimes. At diffusion-dominated frequencies, the frequency-dependent anisotropic properties are mainly determined by the normal stress on the crack faces. In contrast, in Rayleigh scattering regime, they are greatly determined by the applied shear stress. At higher frequencies (Mie scattering regime), affected by the wave reflections between the crack edges, the frequency-dependent anisotropy becomes complex. The angle-dependent velocity can largely deviate from elliptic-shaped profile. As a result, the material properties cannot be described within the framework of the transversely isotropic medium model. Moreover, it is found that the attenuation is sensitive to the fluid compressibility and crack thickness, showing evidences that it is possible to invert fluid saturation and permeability from seismic attenuation. We also conclude that using a simple linear superposition of the attenuations due to wave-induced fluid flow and elastic scattering from their corresponding equivalent medium models will leads to an overestimation of the total attenuation. Our results demonstrate it is necessary to account for the mechanism interference to allow for an adequate estimation of the intrinsic attenuation of cracked porous rocks.

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Xia, Shuang, Alberto Mestas-Nuñez, Hongjie Xie, Jiakui Tang, and Rolando Vega. "Characterizing Variability of Solar Irradiance in San Antonio, Texas Using Satellite Observations of Cloudiness." Remote Sensing 10, no. 12 (December 12, 2018): 2016. http://dx.doi.org/10.3390/rs10122016.

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Since the main attenuation of solar irradiance reaching the earth’s surface is due to clouds, it has been hypothesized that global horizontal irradiance attenuation and its temporal variability at a given location could be characterized simply by cloud properties at that location. This hypothesis is tested using global horizontal irradiance measurements at two stations in San Antonio, Texas, and satellite estimates of cloud types and cloud layers from the Geostationary Operational Environmental Satellite (GOES) Surface and Insolation Product. A modified version of an existing solar attenuation variability index, albeit having a better physical foundation, is used. The analysis is conducted for different cloud conditions and solar elevations. It is found that under cloudy-sky conditions, there is less attenuation under water clouds than those under opaque ice clouds (optically thick ice clouds) and multilayered clouds. For cloud layers, less attenuation was found for the low/mid layers than for the high layer. Cloud enhancement occurs more frequently for water clouds and less frequently for mixed phase and cirrus clouds and it occurs with similar frequency at all three levels. The temporal variability of solar attenuation is found to decrease with an increasing temporal sampling interval and to be largest for water clouds and smallest for multilayered and partly cloudy conditions. This work presents a first step towards estimating solar energy potential in the San Antonio area indirectly using available estimates of cloudiness from GOES satellites.

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Koronakis, P. S., G. K. Sfantos, A. G. Paliatsos, J. K. Kaldellis, J. E. Garofalakis, and I. P. Koronaki. "Interrelations of UV-global/global/diffuse solar irradiance components and UV-global attenuation on air pollution episode days in Athens, Greece." Atmospheric Environment 36, no. 19 (July 2002): 3173–81. http://dx.doi.org/10.1016/s1352-2310(02)00233-9.

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39

Buat, V., M. Boquien, K. Małek, D. Corre, H. Salas, Y. Roehlly, R. Shirley, and A. Efstathiou. "Dust attenuation and Hα emission in a sample of galaxies observed with Herschel at 0.6 < z < 1.6." Astronomy & Astrophysics 619 (November 2018): A135. http://dx.doi.org/10.1051/0004-6361/201833841.

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Context. Dust attenuation shapes the spectral energy distribution of galaxies. It is particularly true for dusty galaxies in which stars experience a heavy attenuation. The combination of UV to IR photometry with the spectroscopic measurement of the Hα recombination line helps to quantify dust attenuation of the whole stellar population and its wavelength dependence. Aims. We want to derive the shape of the global attenuation curve and the amount of obscuration affecting young stars or nebular emission and the bulk of the stellar emission in a representative sample of galaxies selected in IR. We will compare our results to the commonly used recipes of Calzetti et al. and Charlot and Fall, and to predictions of radiative transfer models. Methods. We selected an IR complete sample of galaxies in the COSMOS 3D-HST CANDELS field detected with the Herschel satellite with a signal to noise ratio larger than five. Optical to NIR photometry is available as well as NIR spectroscopy for each source. We reduced the sample to the redshift range 0.6 < z < 1.6 to include the Hα line in the G141 grism spectra. We have used a new version of the CIGALE code to fit simultaneously the continuum and Hα line emission of the 34 selected galaxies. Results. Using flexible attenuation laws with free parameters, we are able to measure the shape of the attenuation curve for each galaxy as well as the amount of attenuation of each stellar population, the former being in general steeper than the starburst law in the UV-optical with a large variation of the slope among galaxies. The attenuation of young stars or nebular continuum is found on average about twice the attenuation affecting older stars, again with a large variation. Our model with power-laws, based on a modification of the Charlot and Fall recipe, gives results in better agreement with the radiative transfer models than the global modification of the slope of the Calzetti law.

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40

Kubota, Takuji, Shinta Seto, Masaki Satoh, Tomoe Nasuno, Toshio Iguchi, Takeshi Masaki, John M. Kwiatkowski, and Riko Oki. "Cloud Assumption of Precipitation Retrieval Algorithms for the Dual-Frequency Precipitation Radar." Journal of Atmospheric and Oceanic Technology 37, no. 11 (November 1, 2020): 2015–31. http://dx.doi.org/10.1175/jtech-d-20-0041.1.

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AbstractAn assumption related to clouds is one of uncertain factors in precipitation retrievals by the Dual-Frequency Precipitation Radar (DPR) on board the Global Precipitation Measurement (GPM) Core Observatory. While an attenuation due to cloud ice is negligibly small for Ku and Ka bands, attenuation by cloud liquid water is larger in the Ka band and estimating precipitation intensity with high accuracy from Ka-band observations can require developing a method to estimate the attenuation due to cloud liquid water content (CLWC). This paper describes a CLWC database used in the DPR level-2 algorithm for the GPM V06A product. In the algorithm, the CLWC value is assumed using the database with inputs of precipitation-related variables, temperature, and geolocation information. A calculation of the database was made using the 3.5-km-mesh global atmospheric simulation derived from the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) global cloud-system-resolving model. Impacts of current CLWC assumptions for surface precipitation estimates were evaluated by comparisons of precipitation retrieval results between default values and 0 mg m−3 of the CLWC. The impacts were quantified by the normalized mean absolute difference (NMAD) and the NMAD values showed 2.3% for the Ku, 9.9% for the Ka, and 6.5% for the dual-frequency algorithms in global averages, while they were larger in the tropics than in high latitudes. Effects of the precipitation estimates from the CLWC assumption were examined further in terms of retrieval processes affected by the CLWC assumption. This study emphasizes the CLWC assumption provided more effects on the precipitation estimates through estimating path-integrated attenuation due to rain.

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Kvale, Karin F., and Katrin J. Meissner. "Primary production sensitivity to phytoplankton light attenuation parameter increases with transient forcing." Biogeosciences 14, no. 20 (October 25, 2017): 4767–80. http://dx.doi.org/10.5194/bg-14-4767-2017.

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Abstract. Treatment of the underwater light field in ocean biogeochemical models has been attracting increasing interest, with some models moving towards more complex parameterisations. We conduct a simple sensitivity study of a typical, highly simplified parameterisation. In our study, we vary the phytoplankton light attenuation parameter over a range constrained by data during both pre-industrial equilibrated and future climate scenario RCP8.5. In equilibrium, lower light attenuation parameters (weaker self-shading) shift net primary production (NPP) towards the high latitudes, while higher values of light attenuation (stronger shelf-shading) shift NPP towards the low latitudes. Climate forcing magnifies this relationship through changes in the distribution of nutrients both within and between ocean regions. Where and how NPP responds to climate forcing can determine the magnitude and sign of global NPP trends in this high CO2 future scenario. Ocean oxygen is particularly sensitive to parameter choice. Under higher CO2 concentrations, two simulations establish a strong biogeochemical feedback between the Southern Ocean and low-latitude Pacific that highlights the potential for regional teleconnection. Our simulations serve as a reminder that shifts in fundamental properties (e.g. light attenuation by phytoplankton) over deep time have the potential to alter global biogeochemistry.

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Taghipour Birgani, Pezhman, Khosro Naderan Tahan, Sina Sodagar, and Mohammad Shishesaz. "Investigation of Lamb waves attenuation in elastic–viscoelastic three-layer adhesive joints in low and high frequencies: Theoretical modeling." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 11 (September 15, 2014): 1939–52. http://dx.doi.org/10.1177/0954406214551037.

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In this paper the attenuation of Lamb waves in three-layer joints, including two elastic plates bonded together by a viscoelastic adhesive layer, is investigated in high and low frequencies using global matrix method. Theoretical boundary value problem in three-layer adhesive joints with perfect bond and traction-free boundary conditions on their outer surfaces is solved to find a combination of frequencies and modes with lowest attenuation. Characteristic equation is derived by applying continuity and boundary conditions in three-layer joints using global matrix method. Attenuation and phase velocity dispersion curves in high and low frequencies are obtained with numerical solution of this equation by a computer code for a three-layer joint, including an aluminum repair patch bonded to the aircraft aluminum skin by a layer of viscoelastic epoxy adhesive. To validate the numerical solution results of characteristic equation, wave structure curves are plotted for a special mode in two different frequencies in the adhesive joint. Also, attenuated displacement amplitude curves in a round-trip of Lamb wave along the adhesive joint are plotted to investigate the reduction of the signal amplitude generated by a single transducer. The purpose of present paper is to find a combination of frequencies and modes with minimum attenuation in high and low frequencies. These frequencies and modes are recognizable by transducers in inspections with Lamb waves because of low attenuation level.

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Jiang, Zhong-Ping. "Global output feedback control with disturbance attenuation for minimum-phase nonlinear systems." Systems & Control Letters 39, no. 3 (March 2000): 155–64. http://dx.doi.org/10.1016/s0167-6911(99)00082-1.

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Battilotti, Stefano, and Leonardo Lanari. "Adaptive disturbance attenuation with global stability for rigid and elastic joint robots." Automatica 33, no. 2 (February 1997): 239–43. http://dx.doi.org/10.1016/s0005-1098(96)00144-6.

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Sznaier, Mario, Rodolfo Suárez, Stefano Miani, and José Alvarez-Ramírez. "Optimall∞ disturbance attenuation and global stabilization of linear systems with bounded control." International Journal of Robust and Nonlinear Control 9, no. 10 (August 1999): 659–75. http://dx.doi.org/10.1002/(sici)1099-1239(199908)9:10<659::aid-rnc428>3.0.co;2-m.

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Wrench, C. L., P. G. Davies, and J. Ramsden. "Global predictions of slant path attenuation on earth-space links at EHF." International Journal of Satellite Communications 17, no. 2-3 (March 1999): 177–86. http://dx.doi.org/10.1002/(sici)1099-1247(199903/06)17:2/3<177::aid-sat633>3.0.co;2-z.

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Luo, Lei, Zhiqun Li, Yan Yao, and Guoxiao Cheng. "A 6-Bit Ku Band Digital Step Attenuator with Low Phase Variation in 0.13-μm SiGe BiCMOS." Electronics 8, no. 10 (October 11, 2019): 1149. http://dx.doi.org/10.3390/electronics8101149.

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A 6-bit Ku band digital step attenuator with low phase variation is presented in this paper. The attenuator is designed with 0.13-μm SiGe BiCMOS process technology using triple well isolation N-Metal-Oxide-Semiconductor (TWNMOS) and through-silicon-via (TSV). TWNMOS is mainly used to improve the performance of switches and reduce the insertion loss (IL). TSV is utilized to provide approximately ideal global current ground plane with low impedance for the attenuator. In addition, substrate floating technique and new capacitance compensation technique are adopted in the attenuator to improve the linearity and decrease the phase variation. The measured results show that the attenuator IL is 6.99–9.33 dB; the maximum relative attenuation is 31.87–30.31 dB with 0.5-dB step (64 states), the root mean square (RMS) for the amplitude error is 0.58–0.36 dB and the phase error RMS is 2.06–3.46° in the 12–17 GHz frequency range. The total chip area is 1 × 0.9 mm2.

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Kheris, Saliha, and Badra Bouabdallah. "Study of the Correction of Effects Chromatic Dispersion and Attenuation to Evaluate the Optical Transmission." Journal of Optical Communications 41, no. 2 (March 26, 2020): 209–14. http://dx.doi.org/10.1515/joc-2019-0010.

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AbstractIn this paper, we have presented a global study of simple bonds, focusing on the main limitations introduced by different optical components as laser source, fiber, optical amplifier, and optical detector. The construction of a long-distance link requires the compensation of attenuation and chromatic dispersion phenomena. Thus, it is well known that the attenuations cause the drop of the signal intensity, whereas the pulse spreading, due to the dispersion, causes the increase of the Bit Error Rate (BER) and consequently the reduction of the signal to noise ratio (SNR). In this purpose, we have calculated the quality factor (Q) issues from the noisy signal’s simulations. We have found a Q of 7.02 to a BER of 0.8 e−12. The founding results match well with fixes norms in telecommunication field.

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Battilotti, S. "Global output regulation and disturbance attenuation with global stability via measurement feedback for a class of nonlinear systems." IEEE Transactions on Automatic Control 41, no. 3 (March 1996): 315–27. http://dx.doi.org/10.1109/9.486315.

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deSilva, Susini, and Vernon F. Cormier. "The relative contributions of scattering and viscoelasticity to the attenuation of S waves in Earth's mantle." Solid Earth 11, no. 1 (January 29, 2020): 161–71. http://dx.doi.org/10.5194/se-11-161-2020.

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Abstract. The relative contributions of scattering and viscoelastic attenuation to the apparent attenuation of seismic body waves are estimated from synthetic and observed S waves multiply reflected from Earth's surface and the core–mantle boundary. The synthetic seismograms include the effects of viscoelasticity and scattering from small-scale heterogeneity predicted from both global tomography and from thermodynamic models of mantle heterogeneity that have been verified from amplitude coherence measurements of body waves observed at dense arrays. Assuming thermodynamic models provide an estimate of the maximum plausible power of heterogeneity measured by elastic velocity and density fluctuations, we predict a maximum scattering contribution of 43 % to the total measured attenuation of mantle S waves having a dominant frequency of 0.05 Hz. The contributions of scattering in the upper and lower mantle to the total apparent attenuation are estimated to be roughly equal. The relative strength of the coda surrounding observed ScSn waves from deep focus earthquakes is not consistent with a mantle having zero intrinsic attenuation.

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Journal articles on the topic 'Global attenuation'

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