Intermodulation Interference-Minimum Frequency Assignment for Satellite SCPC Systems

1984 ◽  
Vol 32 (4) ◽  
pp. 462-468 ◽  
Author(s):  
H. Okinaka ◽  
Y. Yasuda ◽  
Y. Hirata
2001 ◽  
Vol 35 (2) ◽  
pp. 211-228 ◽  
Author(s):  
Philippe Meurdesoif ◽  
Benoît Rottembourg
Keyword(s):  

Author(s):  
V. Lyandres

Introduction:Effective synthesis of а mobile communication network includes joint optimisation of two processes: placement of base stations and frequency assignment. In real environments, the well-known cellular concept fails due to some reasons, such as not homogeneous traffic and non-isotropic wave propagation in the service area.Purpose:Looking for the universal method of finding a network structure close to the optimal.Results:The proposed approach is based on the idea of adaptive vector quantization of the network service area. As a result, it is reduced to a 2D discrete map split into zones with approximately equal number of service requests. In each zone, the algorithm finds such coordinates of its base station that provide the shortest average distance to all subscribers. This method takes into account the shortage of the a priory information about the current traffic, ensures maximum coverage of the service area, and what is not less important, significantly simplifies the process of frequency assignment.


2021 ◽  
pp. 1-12
Author(s):  
Tobias Dienerowitz ◽  
Thomas Peschel ◽  
Mandy Vogel ◽  
Tanja Poulain ◽  
Christoph Engel ◽  
...  

<b><i>Purpose:</i></b> The purpose of this study was to establish and characterize age- and gender-specific normative data of the singing voice using the voice range profile for clinical diagnostics. Furthermore, associations between the singing voice and the socioeconomic status were examined. <b><i>Methods:</i></b> Singing voice profiles of 1,578 mostly untrained children aged between 7.0 and 16.11 years were analyzed. Participants had to reproduce sung tones at defined pitches, resulting in maximum and minimum fundamental frequency and sound pressure level (SPL). In addition, maximum phonation time (MPT) was measured. Percentile curves of frequency, SPL and MPT were estimated. To examine the associations of socioeconomic status, multivariate analyses adjusted for age and sex were performed. <b><i>Results:</i></b> In boys, the mean of the highest frequency was 750.9 Hz and lowered to 397.1 Hz with increasing age. Similarly, the minimum frequency was 194.4 Hz and lowered to 91.9 Hz. In girls, the mean maximum frequency decreased from 754.9 to 725.3 Hz. The mean minimum frequency lowered from 202.4 to 175.0 Hz. For both sexes, the mean frequency range ∆f showed a constant range of roughly 24 semitones. The MPT increased with age, for boys and girls. There was neither an effect of age nor sex on SPL<sub>min</sub> or SPL<sub>max</sub>, ranging between 52.6 and 54.1 dBA and between 86.5 and 82.8 dBA, respectively. Socioeconomic status was not associated with the above-mentioned variables. <b><i>Conclusion:</i></b> To our knowledge, this study is the first to present large normative data on the singing voice in childhood and adolescence based on a high number of measurements. In addition, we provide percentile curves for practical application in clinic and vocal pedagogy which may be applied to distinguish between normal and pathological singing voice.


Author(s):  
Gaurang Ruhela ◽  
Anirvan DasGupta

We consider the problem of a hopping ball excited by a travelling harmonic wave on an elastic surface. The ball, considered as a particle, is assumed to interact with the surface through inelastic collisions. The surface motion due to the wave induces a horizontal drift in the ball. The problem is treated analytically under certain approximations. The phase space of the hopping motion is captured by constructing a phase-velocity return map. The fixed points of the return map and its compositions represent periodic hopping solutions. The linear stability of the obtained periodic solution is studied in detail. The minimum frequency for the onset of periodic hops, and the subsequent loss of stability at the bifurcation frequency, have been determined analytically. Interestingly, for small values of wave amplitude, the analytical solutions reveal striking similarities with the results of the classical bouncing ball problem.


2010 ◽  
Vol 37 (12) ◽  
pp. 2152-2163 ◽  
Author(s):  
Ayed A. Salman ◽  
Imtiaz Ahmad ◽  
Mahamed G.H. Omran ◽  
Mohammad Gh. Mohammad

Sign in / Sign up

Export Citation Format

Share Document