scholarly journals Frequency Spectrum Generated by Thyristor Control

1974 ◽  
Vol 1 (1) ◽  
pp. 43-49 ◽  
Author(s):  
J. K. Hall ◽  
N. C. Jones
Keyword(s):  
Frequency Spectrum ◽  
Noise Level ◽  
High Harmonic ◽  
Resistive Load ◽  
Noise Amplitude ◽  
Harmonic Frequency ◽  
Thyristor Control ◽  
Very High ◽  
Harmonic Noise ◽  
Low Order

This paper describes the measured harmonics in the load currents of thyristor circuits and shows that with firing angle control the harmonic amplitudes decrease sharply with increasing harmonic frequency, but that they extend to very high harmonic orders of around 6000. The amplitudes of the harmonics are a maximum for a firing delay angle of around 90°.Integral cycle control produces only low order harmonics and sub-harmonics.It is also shown that with firing angle control apparently random inter-harmonic noise is present and that the harmonics fall below this noise level at frequencies of approximately 250 KHz for a switched 50 Hz Waveform and for the resistive load used. The noise amplitude decreases with increasing frequency and is a maximum with 90° firing delay.

Electron Microscopy in Molecular Biology

1967 ◽  
Vol 25 ◽  
pp. 2-3
Author(s):  
Cecil E. Hall
Keyword(s):  
Electron Microscopy ◽  
Molecular Biology ◽  
Noise Level ◽  
Molecular Structures ◽  
Material Structure ◽  
The Arts ◽  
Shadow Casting ◽  
Electron Image ◽  
High Degree ◽  
Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

Reducing Noise Polution Generated by the Gas Compresor Compressco Cj 360 in a Residential Area

2015 ◽  
Vol 801 ◽  
pp. 84-89
Author(s):  
Silviu Nicolae Platon ◽  
Adriana Tudor
Keyword(s):  
Risk Factor ◽  
Frequency Spectrum ◽  
Environmental Conditions ◽  
Noise Level ◽  
Work Capacity ◽  
Residential Area ◽  
Sound Insulation ◽  
Technical Solution ◽  
Legal Regulations ◽  
Health Work

Noise – as a risk factor in the environment – in case it exceeds the intensity limits it becomes a biological aggression factor, a medical and social contaminant with implications of prime importance in terms of health, work capacity and comfort.This research is an objective analysis of noise level and frequency spectrum emitted by gas compressor Compressco CJ 360 in order to identify and develop solutions for noise protection required for the establishment of the environmental conditions in accordance with legal regulations in the area desired by the beneficiary. The research proposes a technical solution for closing the compressor with sound insulation prior to placing it in the desired place, in suitable environmental conditions.

scholarly journals Enhanced regime predictability in atmospheric low-order models due to stochastic forcing

2014 ◽  
Vol 372 (2018) ◽  
pp. 20130286 ◽  
Author(s):  
Frank Kwasniok
Keyword(s):  
Noise Level ◽  
Coarse Grained ◽  
Climate Modelling ◽  
Order Model ◽  
Stochastic Forcing ◽  
Barotropic Flow ◽  
Optimal Value ◽  
Weather And Climate ◽  
Flow Over Topography ◽  
Low Order

Regime predictability in atmospheric low-order models augmented with stochastic forcing is studied. Atmospheric regimes are identified as persistent or metastable states using a hidden Markov model analysis. A somewhat counterintuitive, coherence resonance-like effect is observed: regime predictability increases with increasing noise level up to an intermediate optimal value, before decreasing when further increasing the noise level. The enhanced regime predictability is due to increased persistence of the regimes. The effect is found in the Lorenz '63 model and a low-order model of barotropic flow over topography. The increased predictability is only present in the regime dynamics, that is, in a coarse-grained view of the system; predictability of individual trajectories decreases monotonically with increasing noise level. A possible explanation for the phenomenon is given and implications of the finding for weather and climate modelling and prediction are discussed.

High Harmonic Frequency Combs for High Resolution Spectroscopy

2009 ◽  
pp. 843-845
Author(s):  
A. Ozawa ◽  
J. Rauschenberger ◽  
Ch. Gohle ◽  
M. Herrmann ◽  
D. R. Walker ◽  
...  
Keyword(s):  
High Resolution ◽  
High Harmonic ◽  
High Resolution Spectroscopy ◽  
Harmonic Frequency ◽  
Frequency Combs

Minimum Span Frequency Assignment Based on a Multiagent Evolutionary Algorithm

2011 ◽  
Vol 2 (3) ◽  
pp. 29-42
Author(s):  
Jing Liu ◽  
Jinshu Li ◽  
Weicai Zhong ◽  
Li Zhang ◽  
Ruochen Liu
Keyword(s):  
Evolutionary Algorithms ◽  
Evolutionary Algorithm ◽  
Frequency Spectrum ◽  
Multiagent Systems ◽  
Experimental Results ◽  
Frequency Assignment ◽  
Assignment Problems ◽  
The Cost ◽  
Very High

In frequency assignment problems (FAPs), separation of the frequencies assigned to the transmitters is necessary to avoid the interference. However, unnecessary separation causes an excess requirement of spectrum, the cost of which may be very high. Since FAPs are closely related to T-coloring problems (TCP), multiagent systems and evolutionary algorithms are combined to form a new algorithm for minimum span FAPs on the basis of the model of TCP, which is named as Multiagent Evolutionary Algorithm for Minimum Span FAPs (MAEA-MSFAPs). The objective of MAEA-MSFAPs is to minimize the frequency spectrum required for a given level of reception quality over the network. In MAEA-MSFAPs, all agents live in a latticelike environment. Making use of the designed behaviors, MAEA-MSFAPs realizes the ability of agents to sense and act on the environment in which they live. During the process of interacting with the environment and other agents, each agent increases the energy as much as possible so that MAEA-MSFAPs can find the optima. Experimental results on TCP with different sizes and Philadelphia benchmark for FAPs show that MAEA-MSFAPs have a good performance and outperform the compared methods.

scholarly journals Perceived Acoustic Quality and Effect on Occupants’ Satisfaction in Green and Conventional Residential Buildings

Buildings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 24 ◽  
Author(s):  
Agnieszka Zalejska-Jonsson
Keyword(s):  
Noise Level ◽  
Indoor Environment ◽  
Residential Buildings ◽  
General Satisfaction ◽  
Environment Quality ◽  
Environmental Profile ◽  
Indoor Environment Quality ◽  
Acoustic Quality ◽  
The Relationship ◽  
Very High

The study presented in this paper focuses on the subjective opinions of occupants of multistory residential buildings by examining the relationship between occupants’ satisfaction and indoor environment quality, and analysing the effect the problems experienced with noise level may have on general satisfaction and the perceived acoustic quality. The analysis is based on data collected through surveys addressed to adults living in green and conventional buildings. The results show that occupants are very satisfied with their apartments, and subjectively rated acoustic quality received very high scores. The responses indicate that noise from neighbours has been experienced relatively seldom by occupants; however, the analysis shows that it is the factor that has the strongest effect on satisfaction with acoustic quality. We have found that the environmental profile of a building has a significant effect on general satisfaction expressed by occupants; however, this effect has not been confirmed for acoustic quality.

scholarly journals Share-slicing: Friend or Foe?

2019 ◽  
pp. 152-174
Author(s):  
Si Gao ◽  
Ben Marshall ◽  
Dan Page ◽  
Elisabeth Oswald
Keyword(s):  
Open Source ◽  
Real World ◽  
Noise Level ◽  
Side Channel ◽  
Side Channel Attacks ◽  
Great Cost ◽  
Architectural Features ◽  
Security Guarantees ◽  
Very High ◽  
Made In

Masking is a well loved and widely deployed countermeasure against side channel attacks, in particular in software. Under certain assumptions (w.r.t. independence and noise level), masking provably prevents attacks up to a certain security order and leads to a predictable increase in the number of required leakages for successful attacks beyond this order. The noise level in typical processors where software masking is used may not be very high, thus low masking orders are not sufficient for real world security. Higher order masking however comes at a great cost, and therefore a number techniques have been published over the years that make such implementations more efficient via parallelisation in the form of bit or share slicing. We take two highly regarded schemes (ISW and Barthe et al.), and some corresponding open source implementations that make use of share slicing, and discuss their true security on an ARM Cortex-M0 and an ARM Cortex-M3 processor (both from the LPC series). We show that micro-architectural features of the M0 and M3 undermine the independence assumptions made in masking proofs and thus their theoretical guarantees do not translate into practice (even worse it seems unpredictable at which order leaks can be expected). Our results demonstrate how difficult it is to link theoretical security proofs to practical real-world security guarantees.

scholarly journals Off-axis current drive with very high harmonic fast waves for CFETR

2020 ◽  
Author(s):  
Y. Q. Yang ◽  
X. J. Zhang ◽  
Y. P. Zhao ◽  
C. M. Qin ◽  
Y. Z. Mao ◽  
...  
Keyword(s):  
High Harmonic ◽  
Current Drive ◽  
Fast Waves ◽  
Very High
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