Journal Article•
Mathematical Analysis of Random Noise-Conclusion
About: This article is published in Bell System Technical Journal.The article was published on 1945-01-01 and is currently open access. It has received 807 citations till now.
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TL;DR: In this paper, the authors derived a simple two-port conductance matrix whose elements are certain coefficients of the periodic time-dependent diode conductance produced by the local oscillator (pump).
Abstract: The small-signal conversion properties of an Esaki (tunnel) diode are represented by a simple two-port conductance matrix whose elements are certain coefficients of the periodic time-dependent diode conductance produced by the local oscillator (pump). Because of the negative slope in the diode I–V characteristic, arbitrarily high conversion gain is possible when certain conditions are satisfied by these coefficients. In terms of these coefficients and other diode parameters, expressions are derived for such useful converter properties as the load conditions necessary for circuit stability, the minimum noise figure, the maximum gain-bandwidth product, the necessary conditions for a positive mixer conductance at the radio frequency (r.f.) and intermediate frequency (i.f.) ports, and the pump loading necessary for self-excitation. It is shown that under proper conditions partial noise cancellation can occur because of correlation effects arising from the nonstationarity of the shot-noise process in the pumped diode. Most of the theoretical results are illustrated by the data obtained from a detailed numerical Fourier analysis applied to an actual high-frequency Esaki diode characteristic. These calculations show that the lowest noise figure and the highest gain-bandwidth product are obtained when the diode is biased in its negative conductance region.
14 citations
TL;DR: Shot-noise processes are used in applied probability to model a variety of physical systems in, for example, teletraffic theory, insurance and risk theory, and in the engineering sciences.
Abstract: Shot-noise processes are used in applied probability to model a variety of physical systems in, for example, teletraffic theory, insurance and risk theory, and in the engineering sciences. In this paper we prove a large deviation principle for the sample-paths of a general class of multidimensional state-dependent Poisson shot-noise processes. The result covers previously known large deviation results for one-dimensional state-independent shot-noise processes with light tails. We use the weak convergence approach to large deviations, which reduces the proof to establishing the appropriate convergence of certain controlled versions of the original processes together with relevant results on existence and uniqueness.
14 citations
15 Oct 1990-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the effects of random wiggler magnetic field errors on free electron lasers are analyzed analytically adn computationally, and it is shown that transverse focusing of the electron beam is not effective in reducing the phase deviation.
Abstract: The effects of random wiggler magnetic-field errors on free electron lasers are analyzed analytically adn computationally. Wiggler field errors perturb the electron beam as it propagates and lead to a random walk of the beam centroid, δx, as well as cause deviations in the parallel-beam energy, δγ∥, and in the relative phase of the electrons in the ponderomotive wave, δΨ. The phase deviation δΨ is identified as the single most important parameter charaterizing the detrimental effects of wiggler errors. In order to avoid significant reduction in gain, it is necessary for the phase deviation to be small compared to 2π. It is shown that transverse focusing of the electron beam is not effective in reducing the phase deviation. Furthermore, it is shown that beam steering at the wiggler entrance reduces the average phase deviation at the end of the wiggler by 13. The detrimental effects of wiggler errors may be reduced by arranging the magnet poles in an optimal ordering such that the magnitude of the phase deviation is minimized.
14 citations
TL;DR: The ensuing impact representation of the single file dynamics suggests an alternate description of thesingle file diffusion as a geometrically constrained fluctuation mechanism.
Abstract: The anomalous diffusion of a single file of Brownian particles moving on a circle at a given temperature is characterized in terms of nearest-neighbor collisions. The time and the distance a particle diffuses (normally) between two successive collisions are computed numerically; their means, distributions, and correlation functions are determined for different values of the file parameters and reproduced analytically by means of simple phenomenological arguments. Most notably, the jump autocorrelation functions develop slow power-law tails. The ensuing impact representation of the single file dynamics suggests an alternate description of the single file diffusion as a geometrically constrained fluctuation mechanism.
14 citations
01 Jan 2014
TL;DR: This dissertation addresses network reconfiguration and dependability by cognitive measures from multiple perspectives – each covered by a respective part of this work – providing guidelines for cognitive networks design.
Abstract: Radio communication is used in increasingly diversified device typologies. Telecommunications with a reduced detrimental impact on health and environment, and an improved cost-efficiency and working lifetime are expected by institutions, end-users, operators and manufacturers. Moreover, with more networks present or more articulated systems, dependability of the entirety is to be ensured. The related need of efficiency in various compartments – such as in the use energy or the radio spectrum – and of effectiveness in adapting to changing operating conditions can be achieved with cognitive features. This dissertation addresses network reconfiguration and dependability by cognitive measures from multiple perspectives – each covered by a respective part of this work – providing guidelines for cognitive networks design. A rationalising view on cognitive networks with related taxonomies and models includes a discussion on the dynamics and interactions in networks operating closely and simultaneously (here, concurrent networks). While cognitive domains are specified for cognitive functions, with a more generic scope control functions are assigned to topological domains. This allows a flexible exploitation of the system design by decoupling the specification of system functions from their mapping onto network devices that will host them. As interaction plays an important role in many topical scenarios, a model for networked engineered cognitive entities comprising four categories (observation, interworking, consolidation, operation) and two levels (a cognitive frontier and a metacognitive hub) is presented here. Its cognitive phases are considered with regard to the other architectural elements. Moving the focus down to the levers for exploitation of context awareness, are presented solutions for efficient use of resources and dependability in general, considering the network dynamics. For communication link and network adaptation, the effective capacity is captured by a compact-form expression also considering imperfections, while learning is exploited for reducing overhead, and collaboration for fairly maximising energy save.
14 citations