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EN
The phenomenon of stochastic resonance (SR) in a tumor growth model under the presence of immune surveillance is investigated. Time delay and cross-correlation between multiplicative and additive noises are considered in the system. The signal-to-noise ratio (SNR) is calculated when periodic signal is introduced multiplicatively. Our results show that: (i) the time delay can accelerate the transition from the state of stable tumor to that of extinction, however the correlation between two noises can accelerate the transition from the state of extinction to that of stable tumor; (ii) the time delay and correlation between two noises can lead to a transition between SR and double SR in the curve of SNR as a function of additive noise intensity, however for the curve of SNR as a function of multiplicative noise intensity, the time delay can cause the SR phenomenon to disappear, and the cross-correlation between two noises can lead to a transition from SR to stochastic reverse-resonance. Finally, we compare the SR phenomenon for the multiplicative periodic signal with that for additive periodic signal in the tumor growth model with immune surveillance.
EN
The paper presents functionality and operation results of a system for creating dynamic maps of acoustic noise employing the PL-Grid infrastructure extended with a distributed sensor network. The work presented provides a demonstration of the services being prepared within the PLGrid Plus project for measuring, modeling and rendering data related to noise level distribution in city agglomerations. Specific computational environments, the so-called domain grids, are developed in the mentioned project. For particular domain grids, specialized IT solutions are prepared, i.e. software implementation and hardware (infrastructure adaptation), dedicated for particular researcher groups demands, including acoustics (the domain grid “Acoustics”). The infrastructure and the software developed can be utilized mainly for research and education purposes, however it can also help in urban planning. The engineered software is intended for creating maps of noise threat for road, railways and industrial sources. Integration of the software services with the distributed sensor network enables automatic updating noise maps for a specific time period. The unique feature of the developed software is a possibility of evaluating auditory effects which are caused by the exposure to excessive noise. The estimation of auditory effects is based on calculated noise levels in a given exposure period. The outcomes of this research study are presented in a form of the cumulative noise dose and the characteristics of the temporary threshold shift.
3
Content available remote Stochastic tumor growth system with two different kinds of time delay
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Open Physics
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2011
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tom 9
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nr 3
616-620
EN
The dynamical properties of a noise-driven tumor cell growth system are investigated when there exist two different kinds of time delays, in the deterministic and fluctuating forces, respectively. Using the approximation probability density approach, the delayed Fokker-Planck equation is obtained. The effects of two different time delays on the stationary probability distribution (SPD), the mean value and the mean passage time (MFPT) are discussed. It is found that the time delay τ1 in the deterministic force can enhance tumor cell number, while the time delay τ2 in the fluctuating force can induce a decrease in tumor cell numbers. On the other hand, while τ1 can hold back the extinction of tumor cells, τ2 can speed up their extinction.
EN
An analytical expression for the standard deviation of Total Harmonic Distortion (THD) estimation is derived. It applies to the case where the estimator uses sine fitting. It is shown that, in common circumstances, it is inversely proportional to the actual value of THD, the signal-to-noise ratio and the square root of the number of samples. The proposed expression is validated both with numerical simulations and an experimental setup using a Monte Carlo procedure.
EN
Optical neural network (ONN) has been regarded as one of the most prospective techniques in the future, due to its high-speed and low power cost. However, the realization of optical convolutional neural network (CNN) in non-ideal cases still remains a big challenge. In this paper, we propose an optical convolutional networks system for classification problems by applying general matrix multiply (GEMM) technology. The results show that under the influence of noise, this system still has good performance with low TOP-1 and TOP-5 error rates of 44.26% and 14.51% for ImageNet. We also propose a quantization model of CNN. The noise quantization model reaches a sufficient prediction accuracy of about 96% for MNIST handwritten dataset.
EN
The subject presented in this paper refers to measurements and assessment of the corrected sound pressure level values (noise) occurring around a medium-power transformer. The paper presents the values of noise accompanying the operation of the power object before and after its modernization, which consisted in repeated core pressing and replacement of the cooling system. The main aim of the research work was the assessment of the influence of the repair work on the noise level emitted into the environment.
PL
Przedstawiono metody obniżania hałasu eksploatowanych silników elektrycznych. Wykazano ich skuteczność. Podkreślono, iż w przypadku wymiany wentylatorów można uzyskać także obniżenie strat i poprawę współczynnika sprawności.
EN
Presented are methods of lowering noise level of electric motors. Their efficiency is proved. Emphasised is, that one can also achieve lower losses and improve the efficiency coefficient, when replacing fans.
8
Content available remote Effects of noise on periodic orbits of the logistic map
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Open Physics
|
2008
|
tom 6
|
nr 3
539-545
EN
Noise can induce an inverse period-doubling transition and chaos. The effects of noise on each periodic orbit of three different period sequences are investigated for the logistic map. It is found that the dynamical behavior of each orbit, induced by an uncorrelated Gaussian white noise, is different in the mergence transition. For an orbit of the period-six sequence, the maximum of the probability density in the presence of noise is greater than that in the absence of noise. It is also found that, under the same intensity of noise, the effects of uncorrelated Gaussian white noise and exponentially correlated colored (Gaussian) noise on the period-four sequence are different.
9
Content available Risk analysis on scaffoldings exposed to noise
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EN
The article presents the results of environmental tests performed on scaffolding that were focused mainly on the sound level. The parameters on which we base our analysis are the value of daily noise exposure level and peak sound levels on scaffolding. The noise that affects construction workers on scaffolding, may increase the risk of accidents. We present the results of measurements for twenty two scaffolds in five cities. The analyses carried out confirmed the qualitatively expected dependencies but they allowed us to quantify the impact of the noise on which construction workers on the scaffolding are exposed. The noise occurs continuously throughout the day and can cause faster fatigue, thereby it can increase the risk of accidents in noisy work environment.
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EN
The analysis of available literature indicates that tests of products sound quality, which would not involve participation of groups of listeners supposed to evaluate the sounds emitted by these products, are neither carried out in Poland, nor in the world. That results in the fact that the products sound quality is determined on the basis of psychoacoustic information and comprises both objective and subjective factors of sound perception. With reference to those factors and to different life cycles of the machine, an original definition of the “sound quality of the machine” has been developed and presented in this article. The global index of the acoustic quality of the machine, accounting for the relations between the noise level at the workstation and the selected parameters characterising both the machine’s sound activity and the working environment, was adopted as the measure of the sound quality of the machine. The experiments that followed confirmed the appropriateness of the assessment made with the use of the global index of acoustic quality.
EN
In this paper a new method of assessing noise-induced harmful effects on the human hearing system is described. The method proposed determines the cumulative impact on hearing system produced by the excessive noise taking into consideration properties of the human hearing system. Based on the predicted effects of the noise exposure, the new types of noise indicators are engineered. The evaluation of these indicators employed various types of noise. The indicators proposed can improve assessment of the harmful effect caused by the noise exposure. An influence of the type of the critical band representation of the hearing system (Bark or ERB scales) on the noise indicator effectivness is also discussed.
12
Content available remote Ograniczanie ponadnormatywnej emisji hałasu wentylatorów dużej mocy
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PL
Hałas jest czynnikiem szkodliwym, który niekorzystnie oddziałuje na wszystkie organizmy żywe. Stąd oraz z opracowanych na tej podstawie wymogów formalno- prawnych wynika konieczność jego ograniczania. Jednym z bardziej istotnych źródeł hałasu biorąc pod uwagę wielkość populacji, która jest narażona na ich oddziaływanie, są układy wentylacji oraz będące ich głównym źródłem wentylatory. Źródła te charakteryzują się szerokim częstotliwościowym widmem oddziaływania, znacznym poziomem mocy akustycznej, jak również ciągłym charakterem pracy. Ograniczanie ponadnormatywnej emisji hałasu każdego ze źródeł, powinno być prowadzone w oparciu o badania modelowe, dzięki którym. możliwy jest prawidłowy dobór zarówno materiałowych, jak i geometrycznych cech konstrukcyjnych oraz określenie ich wpływu na skuteczność środka redukcji. Niniejszy artykuł opisuje główne źródła hałasu w układach wentylacji, jakie można spotkać zarówno na terenie obiektów energetycznych, powierzchni kopalń, jak również podziemnych wyrobisk górniczych. Przedstawiono skróconą metodykę badań, których celem jest ograniczenie ponadnormatywnej emisji hałasu do środowiska i na stanowiskach pracy oraz przede wszystkim różne konstrukcje biernych środków redukcji hałasu, opisując ich cechy konstrukcyjne.
EN
Noise is a harmful factor which has an unfavourable impact on all living organisms. The necessity of noise reduction results from this fact and from formal-and-legal requirements developed on this basis. Ventilation systems and fans are one of the most significant sources of noise, taking into account the size of population exposed to them. These sources are of wide impact frequency spectrum, considerable level of acoustic power, as well as continuous character of operation. Limitation of above-standard noise emission from each source should be conducted on the basis of model tests, due to which a real selection of both material and geometrical features, as well as determination of their impact on effectiveness of reduction factor, are possible. The main noise sources in ventilation systems, which can be met both in the area of power objects, mines' surface and underground mine workings, were described in the paper. Shortened methodology of tests, which objective is to reduce the above-standard noise emission to the environment and at the workplaces, were presented, as well as different designs of passive means for noise reduction were presented and their design features were described.
EN
Scanning television optical microscope is designed to investigate microscopic objects, larger than 0.1 micrometers. To illuminate microobject with this microscope there is used a high resolution cathode ray tube. Low illumination of the tested microobject lets to explore living microorganisms in real time. The current microscopic image has low contrast. To increase image contrast it is necessary to increase microscope sensitivity. The main sources of noise in scanning television optical microscope are: 1) composite video shaper; 2) photomultiplier tube; and 3) scanning cathode ray tube. Detailed analysis of noise sources in video signal of the microscope is presented in the paper. Equations describing the sources are given. Dependencies are plotted and discussed.
EN
More and more patients are presenting with a clinical suspicion of Central Auditory Processing Disorder (CAPD). In order to make a correct diagnosis, it is necessary for an interdisciplinary team of experts to conduct thorough tests and carry out a reliable analysis of their results. CAPD is a problem diagnosed in patients with normal hearing sensitivity; moreover, their difficulties do not result from cognitive or linguistic impairment, although they can co-occur with these conditions. Specialists recommend three complementary approaches which can improve the functioning of children with CAPD. One of these strategies is to modify their home and school environment. This article provides elaboration on this issue; it also shows the role of the immediate environment in the therapy of a child with CAPD. The guidelines it offers are also useful in the therapy of patients with hearing perception problems.
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EN
Every year engine manufacturers invest billions of euros into research and development of technologies in or-der to improve aircraft noise performance. The success is represented by quieter and more efficient aircraft that represent greener aviation. This paper deals with two most efficient aircraft all over the world – Airbus A350 XWB and Boeing 787 Dreamliner where authors compare technological aspects related to the engine structure and con-sequently its efficiency. Moreover, it describes the main differences between these engines and it compares them from the noise point of view. On the other hand it deals with comparison of noise charges related to these aircraft and their operation at Frankfurt/ Main Airport.
EN
The article discusses the advantages of using an acoustic camera to analyze noise distribution. Location of noise sources was based on example of an autogyro model. Tests were performed using a 16-microphone acoustic camera using Noise Inspector software. Acoustic maps and sound power levels for two aircraft operations conditions were obtained. The results obtained during the various states of the model work were compared.
PL
Wykonano analizę patentów bydgoskiego środowiska naukowego zmniejszających poziom parametrów drgań i emisji hałasu. Przedstawiono również patenty osłon, ekranów i przestrzennych pochłaniaczy akustycznych.
EN
Vibroacoustic patents analysis of Bydgoszcz scientific community reducing the vibration and noise parameters level was done. Shield, screen and special acoustic absorber patents were also presented.
19
Content available remote Źródła hałasu wytwarzanego przez śmigłowiec
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PL
W ostatnich latach duży wysiłek konstruktorów lotniczych i służb eksploatacji lotnisk skierowany jest na ograniczenie hałasu emitowanego przez statki powietrzne. Artykuł zawiera: - klasyfikację hałasu wytwarzanego przez śmigłowiec, - omówienie podstawowych źródeł hałasu emitowanego przez śmigłowiec, - przykładowe widma hałasu wytwarzanego przez elementy śmigłowca. Dokładna analiza hałasu wytwarzanego przez śmigłowiec pomaga konstruktorom lotniczym projektować elementy śmigłowców o optymalnych charakterystykach wibroakustycznych.
EN
In the last few years has been made great effort of aircraft designers and engineers focused on need to minimise level of helicopters noise. This introduction serves to give an overview of issues included in article. They are as follows: - classification of helicopters noise; - description of these sources; - examples of noise spectrum. The exact analysis of helicopters noise help to design elements with optimal vibroacustic characteristics.
20
Content available remote Towards the Design of Low Noise Level Wind Turbines
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EN
According to the authors’ hypothesis generation of high intensity noise is caused by generation of vorticity structures inducing velocities that can be locally higher than the velocity of sound. The localization and magnitude of vorticity concentration can be precisely defined on the basis of a double layer vortex model. Knowing the localization and mechanism of generation of significantly high induced velocities, turbine blades can be shaped in such a way so as to decrease the concentration of vorticity in these zones. According to the hypothesis described in this paper, a modification of turbine blades at the design stage results in their quieter operation for higher loads and wind velocities. The authors base their hypothesis on the experience from design works concerning low noise ship propellers. The following paper focuses on these tasks.
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