Search results for "Frequency spectrum"
showing 8 items of 8 documents
Channel Modeling and System Concepts for Future Terahertz Communications: Getting Ready for Advances Beyond 5G
2020
Future terahertz (THz) communications will utilize the frequency spectrum around 300 GHz. This technology provides a promising solution for future high-data-rate communications due to the high available bandwidth. However, the unfavorable channel characteristics are a major barrier for the realization of THz communications. To address the challenges caused by the unfavorable propagation conditions, the world?s first THz communication standard includes a channel-modeling document (CMD).
Motion of compactonlike kinks.
1999
We analyze the ability of a compactonlike kink (i.e., kink with compact support) to execute a stable ballistic propagation in a discrete Klein-Gordon system with anharmonic coupling. We demonstrate that the effects of lattice discreteness, and the presence of a linear coupling between lattice sites, are detrimental to a stable ballistic propagation of the compacton, because of the particular structure of the small-oscillation frequency spectrum of the compacton in which the lower-frequency internal modes enter in direct resonance with phonon modes. Our study reveals the parameter regions for obtaining a stable ballistic propagation of a compactonlike kink. Finally we investigate the interac…
EMG frequency spectrum, muscle structure, and fatigue during dynamic contractions in man
1979
Fatigue of the vastus lateralis muscle was studied in healthy well-conditioned students, who differed considerable regarding their muscle fibre type distribution. Muscle force decline during repeated maximum voluntary knee extensions at a constant angular velocity (180 degree X s-1 or rad X s-1), using isokinetic equipment, was taken as the criterion for the degree of fatigue. In an attempt to study quantitative as well as qualitative changes in the EMG pattern, integrated EMG (IEMG) and the frequency of the mean power (MPF), computed from the power spectral density function (PSDF), were analysed. It was found that individuals with muscles made up of a high proportion of fast twitch (FT) mu…
Online signal processing of internal anal sphincter activity during pelvic autonomic nerve stimulation: a new method to improve the reliability of in…
2011
Aim Intra-operative neuromonitoring is increasingly applied in several surgical disciplines and has been introduced to facilitate pelvic autonomic nerve preservation. Nevertheless, it has been considered a questionable tool for the minimization of risk, as the results are variable and might be misleading. The aim of the present experimental study was to develop an intra-operative neuromonitoring system with improved reliability for monitoring pelvic autonomic nerve function. Method Fifteen pigs underwent low anterior rectal resection with pelvic autonomic nerve preservation. Intra-operative neuromonitoring was performed under autonomic nerve stimulation with observation of electromyograph…
Broadband microwave gas sensor: A coaxial design
2010
The method of gas detection by a broadband microwave gas sensor is presented in this article. The principle of this method is to use a sensitive material as substrate of a transmission coaxial line. The sensor represents an open line with an extreme surface in contact with gas. The interaction with the gas and the surface induces a dielectric variation of the substrate. From experimental results, the interaction between the sensitive material and each tested gas present a specific frequency spectrum of the reflection coefficient at the input of the line. The proposed method has the advantage of a compact size, wide bandwidth, simple structure, and capable with all sensitive materials. © 201…
The effect of MPEG audio compression on multidimensional set of voice parameters
2002
The MPEG-1 Layer 3 compression schema of audio signal, or commonly known as mp3, has caused a great impact in recent years as it has reached high compression rates while also conserving a high sound quality. Previous listening tests have shown that music and speech samples compressed at high bitrates are virtually indistinguishable from the original samples, but very little is known about how compression acoustically affects the voice signal. In Experiment 1 the spectral composition of original and compressed speech signals were analyzed by means of the Long-Term Average Spectrum using the Computerized Speech Laboratory (Kay Elemetrics Corp. (Pine Brook, NJ, USA)). In Experiment 2 a set of …
Spectral biases in tree-ring climate proxies
2013
Seamless quantification of past and present climate variability is needed to understand the Earth’s climate well enough to make accurate predictions for the future. This study addresses whether tree-ring-dominated proxy data properly represent the frequency spectrum of true climate variability. The results challenge the validity of detection and attribution investigations based on these data. External forcing and internal dynamics result in climate system variability ranging from sub-daily weather to multi-centennial trends and beyond1,2. State-of-the-art palaeoclimatic methods routinely use hydroclimatic proxies to reconstruct temperature (for example, refs 3, 4), possibly blurring differe…
Statistical properties of the site-frequency spectrum associated with lambda-coalescents.
2013
Abstract Statistical properties of the site-frequency spectrum associated with Λ-coalescents are our objects of study. In particular, we derive recursions for the expected value, variance, and covariance of the spectrum, extending earlier results of Fu (1995) for the classical Kingman coalescent. Estimating coalescent parameters introduced by certain Λ-coalescents for data sets too large for full-likelihood methods is our focus. The recursions for the expected values we obtain can be used to find the parameter values that give the best fit to the observed frequency spectrum. The expected values are also used to approximate the probability a (derived) mutation arises on a branch subtending a…