3,491 research outputs found
Voice Compression and Communications: Principles and Applications for Fixes and Wireless Channels
No full textUp-to-date, expert coverage of topics in wireless voice communications Voice communication is the most important facet of mobile radio service. Even when the predicted surge of wireless data and Internet services becomes a reality, voice will remain the most natural means of human communication. Voice Compression and Communications details issues in wireless voice communications and treats compression, channel coding, and wireless transmission as a joint subject. Part I covers background material, whereas Part II provides detailed information on both proprietary and standardized analysis-by-synthesis codecs, including the speech codecs of virtually all existing wireline-based and wireless systems. Parts III and IV discuss mainly research-based wideband, audio, as well as very low-rate schemes likely to find their way into future standards. Voice Compression and Communications describes fundamental concepts in a non-mathematical way early in the book for those with only a background knowledge of signal processing and communications. More advanced readers will find detailed discussions of theoretical principles, future concepts, and solutions to various specific wireless voice communications problems
Revisiting the Faroe Marine Ash Zone III in two Greenland ice cores: Implications for marine-ice correlations
No full textNineteen new Icelandic tephra layers are identified in NGRIP and NEEM ice spanning Greenland Interstadial-9 (GI-9) and the early phase of GI-8 (∼38 000-40 500 b2k). Fourteen tephras are identified in the NGRIP record and five direct correlatives are identified in NEEM, thus indicating the occurrence of 14 separate volcanic events. With two exceptions, the tephras are tholeiitic basalt in composition and despite having very similar geochemical signatures can, in most cases, be discriminated from one another using their TiO2 values. All of these tephra layers fall within the compositional range of the Faroe Marine Ash Zone III (FMAZ III) deposit previously identified in ocean cores from the Faroes region and previously correlated to NGRIP 2066.95m by Davies et al. (). Thus, the FMAZ III in the marine realm is most likely a complex ash zone that represents a series of closely timed Grimsvötn eruptions that, as yet, can only be stratigraphically separated in the high-resolution ice-core records. The geochemical signatures and stratigraphic positions of the new ice-core layers means that the FMAZ III tephra deposit, as currently defined in the marine realm, cannot be correlated to NGRIP 2066.95m or any other ice-core tephra horizons preserved during this interval.</p
1973-10-25 Morehead State Concert and Lecture Series J.P. Donleavy
No full textRenowned author J.P. Donleavy speaks on the plight of an author and the methods to write, recorded on October 25, 1973
BaptisteVandecrux/SEB_Firn_model: GEUS surface energy balance and firn model v0.3
No full textGEUS firn model as used in the article:
Vandecrux, B., Colgan, W., Solgaard, A. M., Steffensen, J.P., Karlsson, N.: Firn Evolution at Camp Century, Greenland: 1966-2100, https://doi.org/10.3389/feart.2021.578978, 2021
Electrical conductivity measurements (ECM) from the GRIP ice core, central Greenland
No full textECM data from the GRIP core obtained with the technique described by Hammer (1980). People involved in the measurements include Henrik B. Clausen, Dorthe Dahl-Jensen, Christine Hvidberg, Niels Gundestrup, Steffen B. Hansen, P. M. Kristinsdottir, Jakob Schwander, and J.P. Steffensen. Data were recorded in parallel on paper in high resolution and digitally in 1 cm resolution. The main core was drilled during the GRIP project in 1989-1992 at the Summit of the Greenland ice sheet. The length is 3025 m. Present-day accumulation 0.23 m ice/yr. Data from the top 101.3 m comes from the S3 shallow core, but the two data sets have been fully integrated on a common depth scale. The data are given as H+ ion concentration versus depth (measured from the undisturbed surface in 1989), but the absolute calibration (H+ = 0.045 I^1.73) must be considered tentative. For more information on the measurements and calibration, see Hammer 1980 and Clausen et al. (1995). Please cite the Hammer (1980), Clausen et al. (1995), and Rasmussen et al. (2023) when using this data file
Entrainment and detrainment rates from the piv measurements at the top of laboratory analogs of stratocumulus and cumulus clouds
No full textWe analyze mixing at the top of laboratory analogs of convective clouds: stratocumulus and cumulus to investigate entrainment of environmental air into the cloud. We retrieve two components of air velocity using Particle Image Velocimetry technique. Suitable image processing allows to determine cloud–clear air interface. Using velocity differences between cloudy and clear sides of the interface we calculate entrainment / detrainment rates
Vortex Dynamics in The Transitional and Turbulent Wake of 6:1 Prolate Spheroid at 45-deg incidence angle
No full textThe incompressible flow past a 6:1 prolate spheroid with an inclination angle of 45o at Re = 3,000 has been studied by means of direct numerical simulations (DNS). The Reynolds number is based on the inflow velocity and minor-axis length. The preliminary results presented here are focused mainly on vortex dynamics and vortical structures in the wake. The wake behind this configuration starts almost symmetric but is soon strongly deflected and bent as it evolves to the intermediate wake. A pair of unequal-strength vortices dominates the intermediate wake, of which one exhibits the shape of a long vortex tube while the other rapidly breaks down into turbulent-like vortical structures
The Global Stratotype Section and Point (GSSP) for the base of the Holocene Series/Epoch (Quaternary System/Period) in the NGRIP ice core
No full textThe Greenland ice core from NorthGRIP (NGRIP) contains a proxy climate record across the Pleistocene– Holocene boundary of unprecedented clarity and resolution. Analysis of an array of physical and chemical parameters within the ice enables the base of the Holocene, as reflected in the first signs of climatic warming at the end of the Younger Dryas/Greenland Stadial 1 cold phase, to be located with a high degree of precision. This climatic event is most clearly reflected in an abrupt shift in deuterium excess values, accompanied by more gradual changes in d18O, dust concentration, a range of chemical species, and annual layer thickness. A timescale based on multi-parameter annual layer counting provides an age of 11,700 yr b2k (before AD2000) for the base of the Holocene, with an estimated 2s uncertainty of 99 yr. It is proposed that an archived core from this unique sequence should constitute the Global Stratotype Section and Point (GSSP) for the base of the Holocene Series/Epoch (Quaternary System/Period)
Experimental characterisation of large scale structures in a high Reynolds number turbulent boundary layer
No full textA very large field of view (4δ x 1δ) with a good spatial resolution owing to the use of four 2k x 2k pixel cameras was conducted in a flat plate boundary layer at two Reynolds numbers (Reθ ≈7,500 and 20,000). Comparing the flow statistics with previously obtained hot-wire data under similar flow conditions show good agreement. The goal of this experiment is to detect and characterise the large scale motions which develop in the log region of a high Reynolds number turbulent boundary layer
Letter from J.P. Bradley to Mr. [William] S. Martin The Dominguez Estate Company, June 28, 1940
No full textRegarding attached payment by Mr. K.L. Schaap settling his account
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