Browsing Articles by Title
Now showing items 799-818 of 859
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Ultrafast Pulse Compression in Bulk with > 20 Times Spectral Broadening Factor from a Single Stage
(2021-11-01)We introduce the combination of multi-pass cell and multi-plate spectral broadening. We demonstrate the compression of 110-μJ pulses from 900-fs to 60-fs in a single stage and report broadening to 38-fs transform-limit by ... -
Ultrawideband Gated Step Frequency Ground-Penetrating Radar
(2012)We describe a prototype ultrawideband radar. We show how the system was designed and how the hardware was developed for the radar prototype. Waveform generation, radar parameters, and signal processing for the stepped ... -
Ultrawideband underwater acoustic communication channels
(2013)Traditional channel models for communications research are designed for narrowband systems. Underwater acoustic communication systems use a bandwidth that is not small compared with the center frequency of the signal and ... -
Under-ice mid-frequency acoustic transmissionand communication in two Arctic Oceanenvironments
(2023-02-23)This paper presents data from mid-frequency (4−8 kHz) under-ice acoustic transmission and communication experiments in the Nansen Basin and in the Beaufort Sea of the Arctic Ocean. Measured impulse responses to range ~10 ... -
Understanding Influence Operations in Social Media: A Cyber Kill Chain Approach
(2020-11-14)Discussions about recent state-run influence operations in social media often focus only on quantitative elements—the number of people interacting with fake news or how many tweets were sent by bots. This article suggests ... -
Understanding the Threat of Nuclear, Biological and Chemical Warfare
(2021)Weapons of mass destruction are not merely Cold War relics. Recent years have seen the use of biological and chemical agents in the United States, Syria, Malaysia and the United Kingdom. The faltering of strategic arms ... -
Underwater Acoustic Communications: Long-Term Test of Turbo Equalization in Shallow Water
(2008)Acoustic telemetry sea trials lasting for three months with experiment periods of 7 h have been carried out, using a turbo receiver. The communication channel is shallow; the depth is approximately 10 m, and the range is ... -
Underwater Acoustic Network Simulation With Lookup Tables From Physical-Layer Replay
(2015)An underwater acoustic network simulation methodology is presented that is based on lookup tables (LUTs) with physical-layer error ratios. These LUTs are prepared with a validated replay channel simulator, which is here ... -
The underwater soundscape of the North Sea
(2024-01)As awareness on the impact of anthropogenic underwater noise on marine life grows, underwater noise measurement programs are needed to determine the current status of marine areas and monitor long-term trends. The Joint ... -
Uniform semiglobal exponential stability of integral line-of-sight guidance laws
(2015)This paper proves that an integral line-of-sight guidance law for path following control of underactuated marine vessels provides uniform semiglobal exponential stability. The stability result is stronger than what has ... -
Uniformly stable wavelets on nonuniform triangulations
(2016)In this paper we construct linear, uniformly stable, wavelet-like functions on arbitrary triangulations. As opposed to standard wavelets, only local orthogonality is required for the wavelet-like functions. Nested ... -
Unimolecular Decomposition Reactions of Picric Acid and its Methylated Derivatives — A DFT Study
(2022-04-26)To handle energetic materials safely, it is important to have knowledge about their sensitivity. Density functional theory (DFT) has proven a valuable tool in the study of energetic materials, and in the current work, DFT ... -
An upper-bound metric for characterizing spectral and spatial coregistration errors in spectral imaging
(2012)Coregistration errors in multi- and hyperspectral imaging sensors arise when the spatial sensitivity pattern differs between bands or when the spectral response varies across the field of view, potentially leading to large ... -
Uptake and effects of 2, 4, 6 - trinitrotoluene (TNT) in juvenile Atlantic salmon (Salmo salar)
(2017)Organ specific uptake and depuration, and biological effects in Atlantic salmon (Salmo salar) exposed to 2, 4, 6-trinitrotoluene (TNT) were studied. Two experiments were conducted, the first using radiolabeled TNT (14C-TNT, ... -
Urban Terrorism in the Arab World: Introducing a Dataset of Jihadist Attack Plots in Jordan
(2021-09-21)Few regions have been more plagued by terrorism than the Arab world. However, knowledge of the phenomenon’s nature is limited by a lack of attack plot data for most Arab countries. This article contributes to addressing ... -
The use of Atlantic hagfish (Myxine glutinosa) as a bioindicator for studies on effect of dumped chemical warfare agents in Skagerrak. 1: Liver histopathology.
(2020)Within the framework of the international project DAIMON (Decision Aid for Marine Munitions), the impact of dumped chemical munitions on fish health was investigated. The Skagerrak Straight (North Sea, at 600 m depth) ... -
The use of Atlantic hagfish (Myxine glutinosa) as a bioindicator species for studies on effects of dumped chemical warfare agents in the Skagerrak. 2. Biochemical biomarkers
(2020)The sea bottom of the Skagerrak Strait (North Sea) contains munitions loaded with chemical warfare agents (CWA), mostly stored in shipwrecks scuttled intentionally after the end of the World War II. The munition shells ... -
Use of n-vector for radar applications
(2018)This paper aims to alert the radar community about the benefits of using n-vector for representing global horizontal position. Unlike other alternatives, n-vector position calculations are simple, vectorized and exact at ... -
The use of synthetic aperture sonar to survey seafloor massive sulfide deposits
(2015)With the advent of advanced deep sea mining technology, seafloor mining is poised to begin on a global scale. For the success of any mining operation, it is crucial that both the operators and regulatory bodies possess ...