Electrochemical Noise: A Clear Corrosion Signature
Homborg, A.M.
2014-01-01
The interpretation of electrochemical noise (EN) data has long been under discussion. Throughout the years, many data analysis techniques have been proposed for this purpose. As a starting point, procedures and parameters that enable identification of, or discrimination between, general and localize
Electrochemical noise measurements of steel corrosion in the molten NaCl-K2SO4 system
Cappeln, Frederik Vilhelm; Bjerrum, Niels; Petrushina, Irina
2005-01-01
Electrochemical noise measurements have been carried out on AISI347, 10CrMo910, 15Mo3, and X20CrMoV121 steels in molten NaCl-K2SO4 at 630 degrees C. Different types of current noise have been identified for pitting, intergranular and peeling corrosion. The corrosion mechanism was the so-called ac......Electrochemical noise measurements have been carried out on AISI347, 10CrMo910, 15Mo3, and X20CrMoV121 steels in molten NaCl-K2SO4 at 630 degrees C. Different types of current noise have been identified for pitting, intergranular and peeling corrosion. The corrosion mechanism was the so......-called active corrosion (i.e., the corrosion proceeds with no passivation due to the influence of chlorine), characterized by the formation of volatile metal chlorides as a primary corrosion product. It was found possible to obtain an empirical separation of general and intergranular corrosion using kurtosis (a...... on this basis. Approximate values of polarization resistances of AISI347 and 15Mo3 steels were determined to be 250 and 100 Omega cm(2), respectively....
Charge Noise in Organic Electrochemical Transistors
Stoop, Ralph L.; Thodkar, Kishan; Sessolo, Michele; Bolink, Henk J.; Schönenberger, Christian; Calame, Michel
2017-01-01
Organic electrochemical transistors (OECTs) are increasingly studied as transducers in sensing applications. While much emphasis has been placed on analyzing and maximizing the OECT signal, noise has been mostly ignored, although it determines the resolution of the sensor. The major contribution to the noise in sensing devices is the 1 /f noise, dominant at low frequency. In this work, we demonstrate that the 1 /f noise in OECTs follows a charge-noise model, which reveals that the noise is due to charge fluctuations in proximity or within the bulk of the channel material. We present the noise scaling behavior with gate voltage, channel dimensions, and polymer thickness. Our results suggest the use of large area channels in order to maximize the signal-to-noise ratio (SNR) for biochemical and electrostatic sensing applications. A comparison with the literature shows that the magnitude of the noise in OECTs is similar to that observed in graphene transistors, and only slightly higher than that found in carbon nanotubes and silicon nanowire devices. In a model ion-sensing experiment with OECTs, we estimate crucial parameters such as the characteristic SNR and the corresponding limit of detection.
Detection of microbiologically influenced corrosion by electrochemical noise transients
Homborg, A.M.; Morales, C.F. Leon; Tinga, Tiedo; de Wit, J.H.W.; Mol, J.M.C.
2014-01-01
This work investigates the electrochemical processes involved in pitting corrosion induced by microbiologically influenced corrosion by using time-resolved instantaneous frequency information of electrochemical current noise (ECN) transients obtained from Hilbert spectra. In addition to the
Electrochemical noise minimization using digital signal processing
Claudia Smaniotto Barin
2004-01-01
Full Text Available This work discusses electrochemical noise in low amplitude signals and reviews the bibliography on signal iltering methods used to reduce noise interference. One of these methods, the Singular Spectrum Analysis (SSA, is described in detail and used to filter some signals in electrostatic deposition experiments. This study also compares results from other filtering techniques such as moving average, Stavitsky-Golay and Fourier and Wavelet, and discusses the advantages and disadvantages of transforms. Results have shown that the SSA method is efficient, of easy applicability, and extremely important for the understanding of electrodeposition characteristics. In the Introduction of this work, the origin of the signals is discussed, and the advantages, problems and the noise filtering techniques related to electrical deposition through microelectrodes are presented. In the Theory section, the SSA method is described, and the reasons for using it with noisy signals are presented. In the Materials and Methods section, the equipment and software used for collecting and processing the signals are described briefly. Finally, in the Results section, the signals reconstructed through SSA, as well as those found in other filtering techniques are presented.
Destructive impact of molecular noise on nanoscale electrochemical oscillators
Cosi, Filippo G.; Krischer, Katharina
2017-06-01
We study the loss of coherence of electrochemical oscillations on meso- and nanosized electrodes with numeric simulations of the electrochemical master equation for a prototypical electrochemical oscillator, the hydrogen peroxide reduction on Pt electrodes in the presence of halides. On nanoelectrodes, the electrode potential changes whenever a stochastic electron-transfer event takes place. Electrochemical reaction rate coefficients depend exponentially on the electrode potential and become thus fluctuating quantities as well. Therefore, also the transition rates between system states become time-dependent which constitutes a fundamental difference to purely chemical nanoscale oscillators. Three implications are demonstrated: (a) oscillations and steady states shift in phase space with decreasing system size, thereby also decreasing considerably the oscillating parameter regions; (b) the minimal number of molecules necessary to support correlated oscillations is more than 10 times as large as for nanoscale chemical oscillators; (c) the relation between correlation time and variance of the period of the oscillations predicted for chemical oscillators in the weak noise limit is only fulfilled in a very restricted parameter range for the electrochemical nano-oscillator.
Monitoring the electrochemical potential noise produced by coated metal electrodes
Metikos-Hukovic, M. (Zagreb Univ. (Yugoslavia). Inst. of Electrochemistry); Loncar, M. (Institute of Metallurgy, Sisak (Yugoslavia)); Zevnik, C. (Iskra-Kibernetika, Kranj (Yugoslavia))
1989-08-01
The protective properties of paints with polyvinyl phenol formaldehyde and cumar resin bases were tested on mild steel using electrochemical noise measurements. Amplitude spectra of low frequency electrochemical potential noise demonstrated a correlation between the rate and form of the corrosion potential. Such results suggest a practical nondestructive electrochemical corrosion monitoring technique for detecting general corrosion and pitting. The corrosion products were subjected to X-ray diffraction analysis and electron-probe microanalysis. (orig.).
Electrochemical thermodynamic measurement system
Reynier, Yvan; Yazami, Rachid; Fultz, Brent T.
2009-09-29
The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.
Latanision, R.M.
1992-06-01
The control of metal dissolution processes is important in fields ranging from battery technology to corrosion. Nevertheless, metal dissolution remains a poorly understood class of electrochemical reactions. Although the reaction sequence for dissolution of many metals have been elucidated, kinetic descriptions are based on area averaged values of parameters that describe the relationship between the rate of reaction and the activation energy. Theoretical and experimental research on metal dissolution has focused traditionally on macroscopic processes and features. However, in the last few years there has been considerable interest in examining these processes on a microscopic scale. This proposal describes a research program to continue our work on theoretical modelling of metal dissolution. Over the next few years, results from theoretical modelling of dissolution, in conjunction with new experimental techniques such as in situ scanning tunneling microscopy, are expected to provide a new insight into the processes controlling metal dissolution and corrosion.
Adaptive Noise Reduction System
Ivana Ropuš
2013-01-01
Full Text Available Noise is an all-present environment pollutant, considered to be one of the greatest contemporary pollutants. World-wide, co-ordinated actions are conducted in order to develop systems which minimise the noise influence onto society.In this article we argue that novel approach to suppression of influence of noise is useful. Furthermore, we argue that the efficient approach is formulation of the efficient, broadly applicable, ubiquituous, adaptive noise-protection system. The approach combines the natural noise-protection form based on plants with the artificially formed coatings.Elements of the system are discussed, its formation and maintenance analysed and perspectives conjectured.
Homborg, A.M.; Westing, E.P.M. van; Tinga, T.; Ferrari, G.M.; Zhang, X.; Wit, J.H.W. de; Mol, J.M.C.
2014-01-01
This study validates the ability of Hilbert spectra to investigate transients in an electrochemical noise signal for an aqueous corrosion inhibition process. The proposed analysis procedure involves the identification and analysis of transients in the electrochemical current noise signal. Their
Electrochemical systems configured to harvest heat energy
Lee, Seok Woo; Yang, Yuan; Ghasemi, Hadi; Chen, Gang; Cui, Yi
2017-01-31
Electrochemical systems for harvesting heat energy, and associated electrochemical cells and methods, are generally described. The electrochemical cells can be configured, in certain cases, such that at least a portion of the regeneration of the first electrochemically active material is driven by a change in temperature of the electrochemical cell. The electrochemical cells can be configured to include a first electrochemically active material and a second electrochemically active material, and, in some cases, the absolute value of the difference between the first thermogalvanic coefficient of the first electrochemically active material and the second thermogalvanic coefficient of the second electrochemically active material is at least about 0.5 millivolts/Kelvin.
Homborg, A.M.; Westing, E.P.M. van; Tinga, T.; Ferrari, G.M.; Zhang, X.; Wit, J.H.W. de; Mol, J.M.C.
2014-01-01
This study validates the ability of Hilbert spectra to investigate transients in an electrochemical noise signal for an aqueous corrosion inhibition process. The proposed analysis procedure involves the identification and analysis of transients in the electrochemical current noise signal. Their deco
Homborg, A.M.; Westing, van E.P.M.; Tinga, T.; Ferrari, G.M.; Zhang, X.; Wit, de J.H.W.; Mol, J.M.C.
2013-01-01
This study validates the ability of Hilbert spectra to investigate transients in an electrochemical noise signal for an aqueous corrosion inhibition process. The proposed analysis procedure involves the identification and analysis of transients in the electrochemical current noise signal. Their deco
Electrochemical hydrogen Storage Systems
Dr. Digby Macdonald
2010-08-09
As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not
CORROSION MONITORING OF LY12 IN SODIUM CHLORIDE SOLUTION WITH ELECTROCHEMICAL NOISE TECHNIQUE
J.Q. Zhang; Z. Zhang; J.M. Wang; H.B. Shao; C.N. Cao
2001-01-01
Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring on a corroding interface. But the noise signal is often difficult to be analyzed due to the complicated nature of the specific systems being investigated. In this paper, the potential noise fluctuations during the free corrosion of commercial aluminum alloy LY12 in sodium chloride solution was recorded and analyzed with different techniques. The typical results showed that the fractal dimension (D,n) obtained from spectral power density (SPD) is mainly directly proportional to the intensity of pitting corrosion and to the value of pitting parameter (SE) derived from dimensional analysis, while the fractal dimension (DE) obtained from EIS is mainly related to the uniform corrosion.
Electrochemical hydrogen Storage Systems
Dr. Digby Macdonald
2010-08-09
As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not
Corrosion monitoring in a straw-fired power plant using an electrochemical noise probe
Cappeln, Frederik Vilhelm; Bjerrum, Niels; Petrushina, Irina
2007-01-01
Electrochemical Noise Measurements have been carried out in situ in a straw-fired power plant using an experimental probe constructed from alumina and AlSl 347 steel. Based on a framework of controlled laboratory experiments it has been found that electrochemical noise has the unique ability...... to provide in-situ monitoring of intergranular corrosion in progress. The probe had a lifetime of two months. It was shown that down-time corrosion in the boiler was negligible. Electrochemical noise data indicated that metal temperatures around 590 degrees C should be avoided as the intergranular corrosion...
Nip, Wing S.; Patraboy, Timothy J.; Anderson, James S.; Rodgers, Geoff; Farrington, Michael D.
1992-02-01
Investigations were conducted into the applicability of electrochemical noise measurement as a tool for diagnosing the state of health and state of charge in lithium batteries. Electrochemical noise is understood to mean the alternating current component of an otherwise direct current measured at the external terminals of the battery, especially random or periodic fluctuations at a microscopic level. A survey of ten commercial primary lithium cell products included three chemical systems (SO2, SOCl2, and MnO2) in a variety of sizes from coin cells to D size from several manufacturers. The cells were subjected to a systematic study of the relationship between noise and rate of discharge, temperature of discharge, temperature cycling, high temperature storage, and vibration exposure. Noise measurements were paralleled with alternating current impedance measurements for comparison. It became clear during the investigations that when a noise measurement identified a cell that was significantly different from the norm, it was a bad cell that would fail to deliver its rated capacity or would present a safety hazard. Often changes in the noise from a given cell were accompanied by changes in some impedance parameters; these changes appeared to be related. Noise measurements were sensitive to many elements of the cell history.
Latanision, R.M.
1992-06-01
The control of metal dissolution processes is important in fields ranging from battery technology to corrosion. Nevertheless, metal dissolution remains a poorly understood class of electrochemical reactions. Although the reaction sequence for dissolution of many metals have been elucidated, kinetic descriptions are based on area averaged values of parameters that describe the relationship between the rate of reaction and the activation energy. Theoretical and experimental research on metal dissolution has focused traditionally on macroscopic processes and features. However, in the last few years there has been considerable interest in examining these processes on a microscopic scale. This proposal describes a research program to continue our work on theoretical modelling of metal dissolution. Over the next few years, results from theoretical modelling of dissolution, in conjunction with new experimental techniques such as in situ scanning tunneling microscopy, are expected to provide a new insight into the processes controlling metal dissolution and corrosion.
STUDY THE INFLUENCE OF H3BO3 ON THE ZINC ELECTROPLATING USING ELECTROCHEMICAL NOISE TECHNIQUE
Z．Zhang; C．S．Wu; Q．Y．Cai; Y．L．Cheng; F．H．Cao; J．Q．Zhang; C．N．Cao
2004-01-01
The influence of H3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that,under the experimental conditions, the deposition of zinc followed the mechanism of two-dimensional nucleation and subsequent grain growth. The addition of H3BO3 into the electroplating solution prominently changes the nucleation and growth kinetics of zinc deposits, which is directly related to the features of electrocrystallization noise and the corresponding structure of the elec.trodeposits. The results also shown that the electrochemical noise (EN) technique can give more information about the electrodeposits structure and electroplating mechanism than other normal electrochemical measurements can give, such as steady-state polarization method and cyclic voltammetry technique.
Energy system comprising an electrochemical energy source
Roozeboom, F.; Notten, P.
2010-01-01
The invention relates to an energy system comprising an electrochemical energy source, wherein said electrochemical energy source comprises at least one assembly of a first electrode, a second electrode, and an intermediate solid-state electrolyte separating said first electrode and said second elec
Three dimensional electrochemical system for neurobiological studies
Vazquez, Patricia; Dimaki, Maria; Svendsen, Winnie Edith
2009-01-01
In this work we report a novel three dimensional electrode array for electrochemical measurements in neuronal studies. The main advantage of working with these out-of-plane structures is the enhanced sensitivity of the system in terms of measuring electrochemical changes in the environment...
Ehsani, A; Mahjani, M G; Hosseini, M; Safari, R; Moshrefi, R; Mohammad Shiri, H
2017-03-15
Inhibition performance of Thymus vulgaris plant leaves extract (thyme) as environmentally friendly (green) inhibitor for the corrosion protection of stainless steel (SS) type 304 in 1.0molL(-1) HCl solution was studied by potentiodynamic polarization, electrochemical impedance (EIS) and electrochemical noise measurements (EN) techniques. The EN data were analyzed with FFT technique to make the spectral power density plots. The calculations were performed by MATLAB 2014a software. Geometry optimization and calculation of the structural and electronic properties of the molecular system of inhibitor have been carried out using UB3LYP/6-311++G(∗∗) level. Moreover, the results obtained from electrochemical noise analysis were compared with potentiodynamic polarization and electrochemical impedance spectroscopy. All of the used techniques showed positive effect of green inhibitor with increasing inhibitor concentration.
Time-frequency methods for trend removal in electrochemical noise data
Homborg, A.M.; Tinga, T.; Zhang, X.; Westing, E.P.M. van; Oonincx, P.J.; Wit, J.H.W. de; Mol, J.M.C.
2012-01-01
Electrochemical current and potential noise signals in many cases exhibit a DC drift that should be removed prior to further data analysis. The theoretical ability of wavelet analysis and empirical mode decomposition to effectively remove only the DC drift component is evaluated based on their mutua
Homborg, A.M.; Westing, E.P.M.; Tinga, Tiedo; Zhang, X; Oonincx, P.J.; Ferrari, G.M.; de Wit, J.H.W.; Mol, J.M.C.
2013-01-01
Hilbert spectra, calculated with the Hilbert–Huang transform, are presented here as an analysis technique for the characterization of electrochemical noise data in corrosion studies. A highly detailed decomposition of the original current and potential data is provided in time and frequency
Garcia-Ocho, E. M.; Genesca, J.
2000-07-01
Anodic passivation of palladium in alkaline medium is studied by means of different electrochemical techniques like potentiodynamic polarization curves, electrochemical impedance spectroscopy and electrochemical noise. A chaotic analysis of electrochemical current noise signals (current oscillations) corresponding to different palladium oxides formed anodically seen to give information about the different potentials characteristics of palladium oxides formation. (Author) 39 refs.
Readout Circuits for Noise Compensation in ISFET Sensory System
Das, M. P.; Bhuyan, M.; Talukdar, C.
2015-12-01
This paper presents two different noise reduction techniques for ion sensitive field effect transistor (ISFET) readout configuration and their comparison. The proposed circuit configurations are immune to the noise generated from the ISFET sensory system and particularly to the low frequency pH dependent 1/ f electrochemical noise. The methods used under this study are compensation of noise by differential OPAMP based and Wheatstone bridge circuit, where two identical commercial ISFET sensors were used. The statistical and frequency analysis of the data generated by this two methods were compared for different pH value ranging from pH 2 to 10 at room temperature, and it is found that the readout circuits are able to compensate the noise to a great extent.
Noise Analysis of MAIA System and Possible Noise Suppression
J. Svihlik
2011-04-01
Full Text Available This paper is devoted to the noise analysis and noise suppression in a system for double station observation of the meteors now known as MAIA (Meteor Automatic Imager and Analyzer. The noise analysis is based on acquisition of testing video sequences in different light conditions and their further statistical evaluation. The main goal is to find a suitable noise model and subsequently determine if the noise is signal dependent or not. Noise and image model in the wavelet domain should be based on Gaussian mixture model (GMM or Generalized Laplacian Model (GLM and the model parameters should be estimated by moment method. Furthermore, noise should be modeled by GMM or GLM also in the space domain. GMM and GLM allow to model various types of probability density functions. Finally the advanced denoising algorithm using Bayesian estimator is applied and its performance is verified.
Development of Active Noise Control System for Quieting Transformer Noise
Lee, Bok Kyu; Song, Seik Young; Choi, Huo Yul [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Yun, Dae Hea; Lee, Hyuk Jae [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)
1997-12-31
The passive noise control technique made use of sound-absorbing or soundproofing materials, so it required a large area and high cost for installation and had a drawback of poor performance at low frequency. Compared to this, the Active Noise Control attenuates noise sound pressure by using secondary source which has same performance ay low-frequency. Furthermore, it is able to save space and expenses. - research on adaptive algorithms - evaluation of global attenuation of the control - computer simulation - real-time Active Noise Control System Hardware Implementation - ANC system setting in the noisy area.
Development of Active Noise Control System for Quieting Transformer Noise
Lee, Bok Kyu; Song, Seik Young; Choi, Huo Yul [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Yun, Dae Hea; Lee, Hyuk Jae [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)
1997-12-31
The passive noise control technique made use of sound-absorbing or soundproofing materials, so it required a large area and high cost for installation and had a drawback of poor performance at low frequency. Compared to this, the Active Noise Control attenuates noise sound pressure by using secondary source which has same performance ay low-frequency. Furthermore, it is able to save space and expenses. - research on adaptive algorithms - evaluation of global attenuation of the control - computer simulation - real-time Active Noise Control System Hardware Implementation - ANC system setting in the noisy area.
Thin Film Inorganic Electrochemical Systems.
1995-07-01
determined that thin film cathodes of LiCoO2 can be readily performed by either spray pyrolysis or spin coating . These cathodes are electrochemically...active. We have also determined that thin film anodes of Li4Ti5O12 can be prepared by spray pyrolysis or spin coating . These anodes are also
Maizia, R.; Dib, A.; Thomas, A.; Martemianov, S.
2017-02-01
Electrochemical noise analysis (ENA) has been performed for the diagnosis of proton-exchange membrane fuel cell (PEMFC) under various operating conditions. Its interest is related with the possibility of a non-invasive on-line diagnosis of a commercial fuel cell. A methodology of spectral analysis has been developed and an evaluation of the stationarity of the signal has been proposed. It has been revealed that the spectral signature of fuel cell, is a linear slope with a fractional power dependence 1/fα where α = 2 for different relative humidities and current densities. Experimental results reveal that the electrochemical noise is sensitive to the water management, especially under dry conditions. At RHH2 = 20% and RHair = 20%, spectral analysis shows a three linear slopes signature on the spectrum at low frequency range (f power spectral density, calculated thanks to FFT, can be used for the detection of an incorrect fuel cell water balance.
Improved Spectrum Analysis Noise Radar Systems.
and evaluated. A new spectrum analysis system designed to detect moving targets is presented. Comparison is made of the detection capabilities of all four noise radar systems in the presence of extraneous noise. (Author)
Z. Zhang; C.S. Wu; Q.Y. Cai; F.H. Cao; J.Q. Zhang
2005-01-01
The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drifi. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints" of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.
Z. Zhang; Q.D. Zhong; J.Q. Zhang; Y.L. Cheng; F.H. Cao; J.M. Wang; C.N. Cao
2002-01-01
Wavelet transforms (WT) are proposed as an alternative tool to overcome the limita-tions of Fourier transforms (FFT) in the analysis of electrochemical noise (EN) data.The most relevant feature of this method of analysis is its capability of decomposingelectrochemical noise records into different sets of wavelet coefficients, which containinformation about the time scale characteristic of the associated corrosion event. Inthis context, the potential noise fluctuations during the free corrosion of pure alu-minum in sodium chloride solution was recorded and analyzed with wavelet transformtechnique. The typical results showed that the EN signal is composed of distinct typeof events, which can be classified according to their scales, i.e. their time constants.Meanwhile, the energy distribution plot (EDP) can be used as "fingerprints" of ENsignals and can be very useful for analyzing EN data in the future.
Macak, Jan [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)]. E-mail: macakj@vscht.cz; Sajdl, Petr [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Kucera, Pavel [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Novotny, Radek [Institute for Energy, Joint Research Centre, 1755ZG Petten (Netherlands); Vosta, Jan [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)
2006-04-25
An in situ corrosion study of austenitic stainless steel 08CH18N10T in high temperature water was performed. The material under study is used in the construction of steam generator of PWR (pressurized water reactor) nuclear power stations and is similar to AISI 321 stainless steel. In situ 300-h tests were performed under autoclave conditions at 280 deg. C and 8 MPa and consisted of impedance measurements, polarization measurements and electrochemical noise measurements. The experiments were performed in deionised water with the pH adjusted to 9.5, in the presence/absence of chlorides. An additional modification of corrosivity was achieved by changing oxygen concentration. A detailed analysis of the impedance data is presented identifying in the impedance spectra contributions of oxide, corrosion reaction, double layer and diffusion process. A good agreement was found between corrosion data from electrochemical impedance spectroscopy (EIS) and that from electrochemical noise (EN) measurements. It was confirmed that the oxide response cannot be attributed to the overall oxide layer but only to the part corresponding to the space charge layer, thus indicating the semi-conductive character of the oxide.
Hernandez Gayosso, M.J.; Zavala Olivares, G.; Ruiz Ordaz, N.; Juarez Ramirez, C.; Garcia Esquivel, R.; Padilla Viveros, A
2004-10-01
The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year{sup -1} were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect.
Electrochemical Noise Chaotic Analysis of NiCoAg Alloy in Hank Solution
D. Bahena
2011-01-01
Full Text Available The potential and current oscillations during corrosion of NiCoAg alloy in Hank solution were studied. Detailed nonlinear fractal analyses were used to characterize complex time series clearly showing that the irregularity in these time series corresponds to deterministic chaos rather than to random noise. The chaotic oscillations were characterized by power spectral densities, phase space, and Lyapunov exponents. Electrochemical impedance was also applied the fractal dimensions for the corroded surface was obtained, and a corrosion mechanism was proposed.
Almeida, E. [INETI/IMP Lab. de Tintas e Revestimentos, Lisboa (Portugal); Mariaca, L.; Rodriguez, A.; Chavarin, J.U.; Veloz, M.A. [IIE Dept. de Fisicoquimica Aplicada, Cuernavaca (Mexico)
1996-12-31
The purpose of the MICAT project (Ibero-American Map of Atmospheric Corrosiveness) was to foster collaborative ventures between groups conducting research on atmospheric corrosion. Overall, 14 Ibero-American countries, including Spain and Portugal, are involved with a network of 71 test stations distributed throughout the region and on 4 continents. These test stations represent a broad spectrum of climatological and atmospheric pollution conditions. The objective of the MICAT electrochemical studies was to characterize the protective properties of the corrosion products formed during atmospheric exposure at the different test sites. Prerusted carbon steel specimens at different locations were immersed in a sodium sulfate solution. Some specimens were rust pretreated in phosphoric acid solution with additions of aluminum hydroxide (rust converters) electrochemically evaluated. Electrochemical noise measurements (ENM) and linear polarization resistance (LPR) measurements were performed for different times of immersion. Corrosion rates were related to the presence of the oxides that were initially formed. For specimens rusted in marine atmospheres, the presence of chlorides in the corrosion products promotes localized attack. As to the different rust-converted specimens, ENM revealed the pretreatment evolution and corrosion performance over time. ENM was able to characterize and evaluate the protective properties of oxides and pretreatments according to the nature and environmental conditions to which specimens were exposed.
In-situ investigation of crevice corrosion by electrochemical noise analysis
Schneider, M. [Technische Univ. Dresden (Germany). Inst. fuer Mater. Sci.; Nocke, K. [Technische Univ. Dresden (Germany). Inst. fuer Mater. Sci.; Pohl, H. [Technische Univ. Dresden (Germany). Inst. fuer Mater. Sci.; Kock, E. [Daimler-Benz Aerospace AG Raumfahrt-Infrastruktur, Bremen (Germany)
1996-12-31
Aluminum and Al-alloys are one of the most important materials in the aircraft industry. The corrosion behaviors are well known for such materials and usually sufficient for applications. A special corrosion phenomen is the crevice corrosion because it is foreseeable and difficult to measure. Aircrafts possess a lot of crevices, especially on riveted connections. The authors used a special corrosion cell for in-situ investigation of crevice corrosion. The influence of small crevices in corrosion behaviors was shown by the evidence of conventionally electrochemical methods. The electrochemical noise analysis is an interesting method to investigate dynamic processes in the initial state of crevice corrosion. J. C. Uruchurtu et al. described in initial processes of pitting corrosion of aluminum in the presence or absence of chloride ions. In this work the authors present results of noise analysis carried out inside small crevices which have a width of between 0.05 and 0.2 mm. Therefore we can test the material under crevice conditions without material damage. We observed the influence of crevices on the surface activation process in sulfate and chloride solutions. (orig.)
ELECTROCHEMICAL NOISE FEATURES OF PURE ALUMINUM DURING PITTING CORROSION IN NEUTRAL NaCl SOLUTION
F.H.Cao; J.Q.Zhang; 等
2003-01-01
Spontaneous electrochemical noise(EN)can be a rich source of information concern-ing the processes simultaneously occurring at a corroding interface.Potential noise fluctuations during the free corrosion of pure aluminum in different concentration of neutral sodium chloride solution are investigated,and the breakdowm and restoration of passive metal's film are studied using potentiodynamic scanning(PDS)measure-ments and electrochemical impedance spectroscopy(EIS)technique.Two capacitance loops are observed in the Nyquist plots in two kinds of concentration,and the corro-sion process is under activation control at first,then become diffusion control within the oxide film and corrosion products of (Al(OH)p-mClm-)accumulated on the surface of the corroding electrode.It is suggested that the pitting corrosion is much easier to occur for pure aluminum in 7.0wt% than in 2.0wt% NaCl solution,and the high concentration of chloride ion in solution inhibits the repassivation of a metastable pit.The corrosion rate deterministic step does not involve Cl-.
Castaneda, I.; Romero, M.; Malo, J.M.; Uruchurtu, J.
2010-07-01
This work presents the electrochemical noise results obtained of the surface degradation on copper, due to erosion corrosion phenomena, which were a function of the hydrodynamic parameters of the system (fluid movement). A modified rotating cylinder (RC) comprising three ring electrodes under two rotating speeds (880 and 1750 rpm with a Reynolds numbers 1486 Re and 2972 Re, respectively) were used. Characteristic electrochemical noise spectra as a function of the hydrodynamic parameters were found, as well as surface attack intensities the noise signal. An increase and a more uniform attack due to particle impact was related to larger particle size and lesser erosion corrosion intensity, in the form of more localized attack over the surface, was obtained for smaller ones. Erosion corrosion attack presents characteristic electrochemical current and potential noise signals, according to the laminar or transitional turbulent regime and particle size added. (Author).
Progress in electrochemical storage for battery systems
Ford, F. E.; Hennigan, T. J.; Palandati, C. F.; Cohn, E.
1972-01-01
Efforts to improve electrochemical systems for space use relate to: (1) improvement of conventional systems; (2) development of fuel cells to practical power systems; and (3) a search for new systems that provide gains in energy density but offer comparable life and performance as conventional systems. Improvements in sealed conventional systems resulted in the areas of materials, charge control methods, cell operations and battery control, and specific process controls required during cell manufacture. Fuel-cell systems have been developed for spacecraft but the use of these power plants is limited. For present and planned flights, nickel-cadmium, silver-zinc, and silver-cadmium systems will be used. Improvements in nickel-cadmium batteries have been applied in medical and commercial areas.
Noise-driven phenomena in hysteretic systems
Dimian, Mihai
2014-01-01
Noise-Driven Phenomena in Hysteretic Systems provides a general approach to nonlinear systems with hysteresis driven by noisy inputs, which leads to a unitary framework for the analysis of various stochastic aspects of hysteresis. This book includes integral, differential and algebraic models that are used to describe scalar and vector hysteretic nonlinearities originating from various areas of science and engineering. The universality of the authors approach is also reflected by the diversity of the models used to portray the input noise, from the classical Gaussian white noise to its impulsive forms, often encountered in economics and biological systems, and pink noise, ubiquitous in multi-stable electronic systems. The book is accompanied by HysterSoft© - a robust simulation environment designed to perform complex hysteresis modeling – that can be used by the reader to reproduce many of the results presented in the book as well as to research both disruptive and constructive effects of noise in hysteret...
Shot noise in radiobiological systems.
Datesman, A
2016-11-01
As a model for human tissue, this report considers the rate of free radical generation in a dilute solution of water in which a beta-emitting radionuclide is uniformly dispersed. Each decay dissipates a discrete quantity of energy, creating a large number of free radicals in a short time within a small volume determined by the beta particle range. Representing the instantaneous dissipated power as a train of randomly-spaced pulses, the time-averaged dissipated power p¯ and rate of free radical generation g¯ are derived. The analogous result in the theory of electrical circuits is known as the shot noise theorem. The reference dose of X-rays Dref producing an identical rate of free radical generation and level of oxidative stress is shown a) to increase with the square root of the absorbed dose, D, and b) to be far larger than D. This finding may have important consequences for public health in cases where the level of shot noise exceeds some noise floor corresponding to equilibrium biological processes. An estimate of this noise floor is made using the example of potassium-40, a beta-emitting radioisotope universally present in living tissue.
Investigation of Noise in Electronic Ultrasonic Systems
Paulius Adomavičius
2011-03-01
Full Text Available Noise models in ultrasonic control system have been investigated. Ultrasonic system channel consist of exciting generator, ultrasonic transducer, amplitude limiter, amplifier, low band filter and A/D converter. The ultrasonic transducers have been described as Von Hippel model, Van Dyke model or improved Van Dyke model. Advantages and disadvantages of these models are discussed in this paper. Noise models of amplitude limiter and linear operational amplifier are presented. The summary results of calculated noise spectral density of ultrasonic system channel have been presented.Article in Lithuanian
Homborg, A.M.; Tinga, T.; Zhang, X.; Westing, van E.P.M.; Oonincx, P.J.; Ferrari, G.M.; Wit, de J.H.W.; Mol, J.M.C.
2013-01-01
Hilbert spectra allow identification of instantaneous frequencies that are attributed to specific corrosion mechanisms in electrochemical noise data. The present work proposes to identify and analyze areas of interest in Hilbert spectra, which enables to obtain valuable frequency information from el
ELECTROCHEMICAL NOISE FEATURES OF PURE ALUMINUM DURING PITTING CORROSION IN NEUTRAL NaCl SOLUTION
F.H. Cao; Z. Zhang; Y.L. Cheng; J.F. Li; J.Q. Zhang; J.M. Wang; C.N. Cao
2003-01-01
Spontaneous electrochemical noise (EN) can be a rich source of information concern-ing the processes simultaneously occurring at a corroding interface. Potential noisefluctuations during the free corrosion of pure aluminum in different concentration ofneutral sodium chloride solution are investigated, and the breakdown and restorationof passive metal's film are studied using potentiodynamic scanning (PDS) measure-ments and electrochemical impedance spectroscopy (EIS) technique. Two capacitanceloops are observed in the Nyquist plots in two kinds of concentration, and the corro-sion process is under activation control at first, then become diffusion control withinthe oxide film and corrosion products of (Al(OH)p-m Cl-m) accumulated on the surfaceof the corroding electrode. It is suggested that the pitting corrosion is much easierto occur for pure aluminum in 7.0wt% than in 2.0wt% NaCl solution, and the highconcentration of chloride ion in solution inhibits the repassivation of a metastable pit.The corrosion rate deterministic step does not involve Cl-.
Ambiguity noise analysis of a SAR system
Tian, Haishan; Chang, Wenge; Li, Xiangyang
2015-12-01
The presence of range and azimuth (or Doppler) ambiguities in synthetic aperture radars (SARs) is well known. The ambiguity noise is related to the antenna pattern and the value of pulse repetition frequency (PRF). Because a new frequency modulated continuous wave (FMCW) SAR has the characters of low cost and small size, and the capacity of real-time signal processing, the antenna will likely vibrate or deform due to a lack of the stabilized platform. And the value of PRF cannot be much high because of the high computation burden for the real-time processing. The aim of this study is to access and improve the performance of a new FMCW SAR system based on the ambiguity noise. First, the quantitative analysis of the system's ambiguity noise level is performed; an antenna with low sidelobes is designed. The conclusion is that the range ambiguity noise is small; the azimuth ambiguity noise is somewhat increased, however, it is sufficiently small to have marginal influence on the image quality. Finally, the ambiguity noise level is measured using the imaging data from a Ku-band FMCW SAR. The results of this study show that the measured noise level coincides with the theoretical noise level.
Use of Electrochemical Noise to Assess Corrosion in Kraft Continuous Digesters
Pawel, S.J.
2004-11-29
Electrochemical noise (EN) probes were deployed in two continuous kraft digesters at a variety of locations representative of corrosion throughout the vessels. Current and potential noise, the temperature at each probe location, and the value of up to 60 process parameters (flow rates, liquor chemistry, etc.) were monitored continuously during each experiment. The results indicate that changes in furnish composition and process upsets were invariably associated with concurrent substantial changes in EN activity throughout the vessels. Post-test evaluation of the mild steel electrode materials in both vessels confirmed general corrosion of a magnitude consistent with historical trends in the respective vessels as well as values qualitatively (and semi-quantitatively) related to EN current sums for each electrode pair. Stainless steel electrodes representing 309LSi and 312 overlay repairs exhibited zero wastage corrosion--as did the actual overlays--but the EN data indicated periodic redox activity on the stainless steel that varied with time and position within the vessel. Little or no correlation between EN probe activity and other operational variables was observed in either vessel. Additional details for each digester experiment are summarized.
1/f noise: diffusive systems and music
Voss, R.F.
1975-11-01
Measurements of the 1/f voltage noise in continuous metal films are reported. At room temperature, samples of pure metals and bismuth (with a carrier density smaller by 10/sup 5/) of similar volume had comparable noise. The results suggest that the noise arises from equilibrium temperature fluctuations modulating the resistance. Spatial correlation of the noise implied that the fluctuations obey a diffusion equation. The empirical inclusion of an explicit 1/f region and appropriate normalization lead to excellent agreement with the measured noise. If the fluctuations are assumed to be spatially correlated, the diffusion equation can yield an extended 1/f region in the power spectrum. The temperature response of a sample to delta and step function power inputs is shown to have the same shape as the autocorrelation function for uncorrelated and correlated temperature fluctuations, respectively. The spectrum obtained from the cosine transform of the measured step function response is in excellent agreement with the measured 1/f voltage noise spectrum. Spatially correlated equilibrium temperature fluctuations are not the dominant source of 1/f noise in semiconductors and metal films. However, the agreement between the low-frequency spectrum of fluctuations in the mean-square Johnson noise voltage and the resistance fluctuation spectrum measured in the presence of a current demonstrates that in these systems the 1/f noise is also due to equilibrium resistance fluctuations. Loudness fluctuations in music and speech and pitch fluctuations in music also show the 1/f behavior. 1/f noise sources, consequently, are demonstrated to be the natural choice for stochastic composition. 26 figures, 1 table. (auth)
Noise-Induced Riddling in Chaotic Systems
Lai, Y.; Grebogi, C. [Departments of Physics and Astronomy and of Mathematics, The University of Kansas, Lawrence, Kansas 66045 (United States)]|[Institute for Plasma Research, The University of Maryland, College Park, Maryland 20742 (United States)
1996-12-01
Recent works have considered the situation of riddling where, when a chaotic attractor lying in an invariant subspace is {ital transversely} {ital stable}, the basin of the attractor can be riddled with holes that belong to the basin of another attractor. We show that riddling can be induced by arbitrarily small random noise {ital even} {ital if} {ital the} {ital attractor} {ital is} {ital transversely} {ital unstable}, and we obtain universal scaling laws for noise-induced riddling. Our results imply that the phenomenon of riddling can be more prevalent than expected before, as noise is practically inevitable in dynamical systems. {copyright} {ital 1996 The American Physical Society.}
王会立; 陈希信
2004-01-01
The optimum state filter and fixed-interval smoother and the optimum deconvolution algorithm for system with multiplicative noise are derived upon the condition that the dynamic noise correlates itself in one-step and correlates with the measurement noise at the present step as well as one past step, and the multiplicative noise is white and statistically independent of the dynamic noise and the measurement noise. A simulation example demonstrates the effectiveness of the above-mentioned deconvolution algorithm.
YING Diwen; JIA Jinping; ZHANG Lehua
2007-01-01
An electrochemical-activated denitrifying biofilm system consisting of activated carbon fiber electrodes immobilized with denitrifying bacteria film as cathode was studied.A revised model for an electrochemical-activated denitrifying biofilm was developed and validated by electrochemical analysis of cathodal polarization curves and nitrate consumption rate.The cathodal polarization curve and nitrate consumption rate were introduced to verify the rate of electrochemical reaction and the activity of denitrifying bacteria,respectively.It was shown that the denitrification process effectively strengthened the electrochemical reaction while the electron also intensified denitrification activity.Electron was transferred between electrochemical process and biological process not only by hydrogen molecule but also by new produced active hydrogen atom.Additionally,a parameter of apparent exchange current density was deprived from the cathodal polarization curve with high overpotential,and a new bio-effect current density was defined through statistical analysis,which was linearly dependent to the activity of denitrification bacteria.Activated carbon fiber (ACF) electrode was also found to be more suitable to the electrochemical denitrifying system compared with graphite and platinum.
Betancourt, N.
2003-12-01
Full Text Available The present work reports the evaluation of aluminum and anodized aluminum by electrochemical noise, as a part of the PATINA/CYTED project of the working group Nº 5. A visual examination is also made. The samples were exposed at several Ibero-American atmospheres up to 2 years of exposure. Different thickness of anodized aluminum were evaluated. The electrochemical potential noise of the 5 μm unexposed sample (pattern showed a different behaviour to that showed by the other anodized specimens. This could be due to a slower sealed of the samples of higher thickness. The same behaviour was observed on the samples exposed at the rural station El Pardo. According to the visual examination, the samples of bare aluminum and those of anodized 5 μm thickness were the most affected by pitting corrosion in the highly polluted atmospheres. A good correlation between corrosion behaviour determined by visual examination and EN was obtained.
Como parte de las investigaciones de la Red PATINA el grupo de trabajo Nº 5 dedicó su atención al comportamiento del aluminio desnudo y anodizado con diferentes espesores en diferentes atmósferas de Iberoamérica. En el presente trabajo se presenta una evaluación de patrones de aluminio 99,5 % de pureza desnudo y anodizado con espesores de 15 y 25 μm, mediante ruido electroquímico. Los resultados obtenidos se comparan con el comportamiento determinado en diferentes atmósferas durante un período de 2 años. El ruido de voltaje del patrón de 5 μm de espesor presenta un comportamiento diferente al de los restantes espesores, lo que coincide con una mayor susceptibilidad a la corrosión picadura de este primer anodizado. Se reportan también algunas diferencias en el ruido de corriente. Se concluye que mediante la utilización del ruido electroquímico es posible caracterizar el aluminio con respecto a su sensibilidad a la corrosión picadura en condiciones atmosféricas.
Pawel, SJ
2003-06-18
Electrochemical noise (ECN) probes were deployed in a carbon steel continuous kraft digester at four locations and at one location in the bottom cone of the associated flash tank. The probes consisted of carbon steel electrodes, representing the vessel construction material, and 309LSi stainless steel overlay electrodes, representing the weld overlay repair in a portion of the vessel. Current and potential noise, the temperature at each probe location, and the value of about 32 process parameters (flow rates, liquor chemistry, etc.) were monitored continuously for a period of almost one year. Historical vessel inspection data and post-test evaluation of the probe components were used to assess/compare ECN corrosion activity with physical changes in wall thickness and corrosion patterns on the digester shell. In addition, attempts were made to correlate ECN activity from each electrode type with process parameters. The results indicate the high general corrosion rates of steel observed just below the extraction screens--on the order of 35 mils/y for the past few years--accelerated further during the period of probe deployment. The maximum wastage of steel (normalized to one full year exposure) was about 85 mils/y at the ring 6N probe just below the extraction screens. Consistent with recent historical observations, the steel corrosion rate at the ring 6S probe--at the same elevation but directly across the digester from ring 6N--was significantly lower at about 50 mils/y. Just prior to probe deployment, the digester shell below the extraction screens was overlaid with 309LSi stainless steel, which was observed to be essentially immune to corrosion at this location. While the ECN probes detected differences in electrochemical behavior between steel probes and between 309LSi probes at rings 6N and 6S, there was only poor quantitative correlation of current sums with actual corrosion rates at these locations. A significant contribution of redox reactions on both steel
Pawel, SJ
2002-05-09
Electrochemical noise (ECN) probes were deployed in a carbon steel continuous kraft digester at five locations roughly equi-spaced from top to bottom of the vessel. Current and potential noise, the temperature at each probe location, and the value of about 60 process parameters (flow rates, liquor chemistry, etc.) were monitored continuously for a period of one year. Historical vessel inspection data, including inspections accomplished immediately prior to and immediately following probe deployment, and post-test evaluation of the probe components were used to assess/compare corrosion indications from the probes with physical changes in wall thickness and corrosion patterns on the digester shell. The results indicate that furnish composition is a significant variable influencing digester corrosion, with increasing amounts of Douglas fir in the nominal furnish correlating directly with increased corrosion activity on the ECN probes. All five probes detected changes in furnish composition approximately simultaneously, indicating rapid chemical communication through the liquor, but the effect was strongest and persisted longest relatively high in the digester. The ECN probes also indicate significant corrosion activity occurred at each probe position during shutdown/restart transients. Little or no correlation between ECN probe corrosion activity and other operational variables was observed. Post-test evaluation of the probes confirmed general corrosion of a magnitude that closely agreed with corrosion current sums calculated for each probe over the exposure period and with historical average corrosion rates for the respective locations. Further, no pitting was observed on any of the electrodes, which is consistent with the ECN data, relevant polarization curves developed for steel in liquor removed from the digester, and the post-test inspection of the digester.
IDENTIFICATION FOR WIENER SYSTEMS WITH INTERNAL NOISE
Qijiang SONG; Hanfu CHEN
2008-01-01
This paper considers identification of Wiener systems for which the internal variables and output are corrupted by noises. When the internal noise is a sequence of independent and identically distributed (iid) Gaussian random variables, by the Weierstrass transformation (WT) the system under consideration turns to be a Wiener system without internal noise. The nonlinear part of the latter is nothing else than the WT of the nonlinear function of the original system, while the linear subsystem is the same for both systems before and after WT. Under reasonable conditions, the recursive identification algorithms are proposed for the transformed Wiener system, and strong consistency for the estimates is established. By using the inverse WT the nonparametric estimates for the nonlinearity of the original system are derived, and they are strongly consistent if the nonlinearity in the original system is a polynomial. Similar results also hold in the case where the internal noise is non-Gaussian. Simulation results are fully consistent with the theoretical analysis.
Kucera, P.; Macak, J.; Sajdl, P. [Institute of Chemical Technology, Prague (Czech Republic); Novotny, R. [Institute for Energy, Joint Research Centre, Petten (Netherlands)
2008-09-15
The corrosion behaviour of pressurized water reactor (PWR) steam generator tube material (08CH18N10T steel) was studied by electrochemical noise (EN) measurements and electrochemical impedance spectroscopy in high-temperature water at 280 C and 8 MPa. Long-term measurements were performed in two electrolytes: (i) deionised water alkalized to pH{sub 25}=9.5 by KOH; (ii) the same electrolyte with 200 ppm of chlorides added (as KCl). The noise data were processed by two filtering methods and the noise resistance and spectral noise resistance values were calculated. Different contributions to the total impedance were identified and the polarization resistance values were calculated from EIS data. Noise and polarization resistances were compared and the influence of filtering methods was discussed. Instantaneous corrosion data were transformed to integral ones and comparison with mean corrosion current estimated from the oxide thickness was made. It was confirmed that the crucial point of EN analysis is selection of proper cut-off frequency in high-pass fast Fourier transform (HP-FFT). (Abstract Copyright [2008], Wiley Periodicals, Inc.)
高云芳; 张昭; 李劲风; 曹发和; 程英亮; 张鉴清
2003-01-01
The potential noise during corrosion of pure aluminum in sodium chloride solution was recorded and analyzed with wavelet transform technique. The typical results show that the electrochemical noise (EN) signal is composed of distinct type of events, which can be classified according to their scales, i.e. time constants. And the process underlying the rapid fluctuations of EN, which is characterized by a small scaling value, i.e. high-frequency components and which is usually used for local analysis, is not consistant with time; whilst those associated with slower processes or characterized by a large scaling value, which are usually used for global analysis, are continuous.
Phase Noise in Photonic Phased-Array Antenna Systems
Logan, Ronald T., Jr.; Maleki, Lute
1998-01-01
The total noise of a phased-array antenna system employing a photonic feed network is analyzed using a model for the individual component noise including both additive and multiplicative equivalent noise generators.
In-situ monitoring of nickel electrodeposit structure using electrochemical noise technique
无
2006-01-01
The nickel electroplating process was investigated by means of electrochemical noise(EN), cyclic voltammetry in conjunction with the scanning electron microscopy(SEM) technique. The results show that, in the experimental conditions and with the increase of current density, the growth mechanism of nickel crystallites changes from 2-D to 3-D with the potential turning point of about - 1.15 V,and the potential for the onset of diffusion control of the ensemble nickel electroplating process was about -1.4 V. In the case of activation-control, the two-dimensional (2-D) nucleation / growth process of nickel often results in the electrocrystallization EN features of only slowly small positive potential drift and the corresponding compact layer-by-layer deposit structure, and the maximum relative energy of the RP-EDP (re-plotted relative energy distribution plot), which is obtained from wavelet analysis, defined in the region with smaller scales. While under the diffusion-control, the three-dimensional (3-D) nucleation / growth process of nickel, often results in the electrocrystallization EN features of both the fast positive potential drift and subsequent remarkable negative potential drift and the corresponding dentritic/large conglomerate structure of nickel deposit, and the maximum relative energy of the RP-EDP defined in the region with larger scales. The electroplating time affects the nickel deposit structure mainly through its influence on the growth rate of crystallites and the Ni2+ ions diffusion process around each crystallite.
ZHANG Li-jun; ZHU Xu-bei; ZHANG Zhao; ZHANG Jian-qing
2009-01-01
The corrosion process of AZ91D magnesium alloy in neutral 1% (mass fraction) sodium chloride aqueous solution was investigated by electrochemical noise(EN), SEM and EDX. Fractal theory was primarily used to depict the corrosion process of the alloy. The fast wavelet transform(FWT), as well as the fast Fourier transform(FFT), was employed to analyze the EN data. The results show that the overall corrosion process can be described by three stages. The first stage corresponds to the pit nucleation and growth; the second stage involves the growth of a passive oxide layer; and the third stage involves reactivation. With increasing immersion time, fractal dimension increases fast initially, fluctuates in the medium and increases again at last. Pitting corrosion and fractal dimension increase due to the initiation and formation of pits in the initial and the end of immersion, while depresses due to the passivation in the medium period. The results of SEM and EDX support the above conclusions.
Noise and vibration in friction systems
Sergienko, Vladimir P
2015-01-01
The book analyzes the basic problems of oscillation processes and theoretical aspects of noise and vibration in friction systems. It presents generalized information available in literature data and results of the authors in vibroacoustics of friction joints, including car brakes and transmissions. The authors consider the main approaches to abatement of noise and vibration in non-stationary friction processes. Special attention is paid to materials science aspects, in particular to advanced composite materials used to improve the vibroacoustic characteristics of tribopairs The book is intended for researchers and technicians, students and post-graduates specializing in mechanical engineering, maintenance of machines and transport means, production certification, problems of friction and vibroacoustics.
Noise analysis in power distribution systems
Danisor, Alin
2016-12-01
This paper proposes an analysis, especially in time domain, of the electrical noise existent on the power distribution lines. This study is important for the use of powerlines as a channel of information transmissions. This information may refer to analog signals and as well to digital signals. The main problem addressed in this paper consists in the characterization of the background noise and to establish his statistical proprieties. It is very important to know if the noise induced in the transmission channel is a stationary one, or even an ergodic one. The main parameters like the mean value, the mean square value were determined in this paper. The approximation of the probability density function of each statistical parameter was studied. The pulses induced in the transmission channel by the transient phenomena of the power electrical systems were considered deterministic signals and their contributions were not included in this study.
Developing active noise control systems for noise attenuation in ducts
Campos, Rosely V.; Ivo, Rodrigo C.; Medeiros, Eduardo B.
2002-11-01
The present work describes some of the research effort on Active Noise Control (ANC) being jointly developed by the Catholic University of Minas Gerais (PUC-MINAS) and the Federal University of Minas Gerais (UFMG). Considerations about the implementation of Digital Signal Processing for noise control in ducts has been presented. The objective is to establish a study on Active Noise Control in ducts combining geometry and acoustic parameters modification together with adaptive digital filtering implementation. Both algorithm and digital signal processing details are also discussed. The main results for a typical application where real attenuation has been obtained are presented and considered according to their use in developing real applications. The authors also believe that the present text should provide an interesting overview for both designers and students concerned about Active Noise Control in ducts. (To be presented in Portuguese.)
Identifying electrochemical effects in a thermal-electrochemical co-driven system for CO2 capture.
Liu, Guang X; Yu, Yun S; Hong, Ying T; Zhang, Zao X; Wei, Jin J; Wang, Geoff G X
2017-05-24
Currently, the most promising amine absorption system for CO2 capture still faces the challenges of heavy steam consumption and a high energy penalty. Thus, a new thermal-electrochemical co-driven system (TECS) for CO2 capture was developed to resolve these problems. In the TECS, unknown electrochemical behaviors are quite essential to assess the CO2 capture performance. Electrochemical experiments were designed using response surface methodology (RSM) to identify electrochemical effects. The results show that the cathode process is slow and difficult, which is the main limitation in improving the performance of the TECS. Forced convection is necessary to improve the diffusion-controlled process and accelerate desorption. Four factors (Cu(ii) molality, CO2 loading, temperature, KNO3 molality) play an auxo-action role in determining anode and cathode reaction rates. A regression model is developed based on the experimental data, and optimum operating conditions are obtained. Regeneration energy consumption reaches about 1.3 GJ per t CO2, a decline of up to 70% compared with the traditional process. In addition, preliminary CO2 desorption experiments suggest that the mass transfer ascribed to the electrochemical process accounts for over 50% of the overall mass transfer coefficient in the CO2 desorption process.
Possibilities for extremophilic microorganisms in microbial electrochemical systems
Dopson, Mark; Ni, Gaofeng; Sleutels, Tom HJA
2015-01-01
Microbial electrochemical systems exploit the metabolism of microorganisms to generate electrical energy or a useful product. In the past couple of decades, the application of microbial electrochemical systems has increased from the use of wastewaters to produce electricity to a versatile technology that can use numerous sources for the extraction of electrons on the one hand, while on the other hand these electrons can be used to serve an ever increasing number of functions. Extremophilic mi...
A new electrochemical oscillatory system of bromate in alkaline solution
无
2007-01-01
A new electrochemical oscillatory system of bromate in alkaline solution is reported. In PtBromate-Alkaline solution system, two different types of electrochemical oscillations (Type Ⅰ and Type Ⅱ) can be observed. Type Ⅰ appears before hydrogen evolution and Type Ⅱ involves periodic hydrogen evolution. Type Ⅰ relates to the adsorption/desorption of the hydrogen on platinum electrode, and Type Ⅱ with periodic oscillation stems from the coupling of electrochemical reactions (the reduction of bromate and evolution hydrogen reaction) with mass transfer (diffusion and convection). More over, under the right conditions, the two types appear in different oscillatory modes, for example,simple periodical mode and mixed one, etc,, Crossed cycle in the cyclic voltammograms, which is the basiccharacteristics for electrochemical oscillatory systems, has also been observed as expected.
Sanchez-Amaya, J. M.; Bethencourt, M.; Gonzalez-Rovira, L.; Botana, F. J.
2009-07-01
Electrochemical noise (EN) is a technique that allows the estimation of both the rate and the corrosion mechanism of different metallic alloys by means of the measurement and the analysis of the fluctuations of current and voltage. Its main advantage against other electrochemical techniques is that during the measurement process, the corrosive systems under study are not instrumentally disturbed, and therefore, the systems are kept at their natural corrosion potential. Two steps are necessary to use this technique: measurement and analysis of the EN signals. In this paper, the most important concepts related only to the measurement of EN are revised. The parameters most employed in the literature to analyse the EN signals will be described in another paper. In the present article, the experimental devices normally used to measure EN signals are firstly analysed. Subsequently, the most important properties of the EN signals are studied. Finally, the external sources of instrumental noise that can affect to the EN signals are described. (Author) 65 refs.
ENTROPY, INFORMATION, NOISE - STUDIES ON SYSTEM EVOLUTION
Weimin ZHENG
2003-01-01
Universe, ecosystem, social system, etc. are evolving systems. The evolving processes of thesesystems have gradual small changes and rapid drastic changes with uncertainties under the constraintsof environment. Systems, as a whole, are evolving toward complexity, diversity and variety withfluctuations and jumps. New order emerges from "mutations". The evolution is bothchance-dependent and path-dependent. In this paper three basics: entropy, information and noise areemphasized with regard to system evolution which is a field that can give people wisdom to solvesystem problems with domain knowledge.
Electrochemical behavior of dental implant system before andafter clinical use
Chae-Heon CHUNG; Hee-Jung KIM; Yong-Tae JEONG; Mee-Kyoung SON; Yong-Hoon JEONG; Han-Cheol CHOE
2009-01-01
Electrochemical behavior of dental implant system before and after clinical use (in vivo and in vitro) was researched by using abutment and titanium fixture. To simulate an oral environment, the samples of clinically used and non-used implant systems as a working electrode were exposed to artificial saliva at (36.5±1) ℃. Electrochemical tests were carried out using a potentiostat. After electrochemical test, the corrosion morphology of each sample was investigated by FE-SEM and EDS. The corrosion potential and pitting potential of clinically used implant system are lower than those of non-used implant system, and clinically used implant system exhibits a lower range of passivation, indicating a less degree of inherent resistance against chloride ion. The polarization resistance decreases in the case of clinically used implant system, whereas, Rp for clinically non-used implant system increases compared with clinically used implant system.
A compact analytical formalism for current transients in electrochemical systems
Nair, Pradeep R
2011-01-01
Micro and nanostructured electrodes form an integral part of a wide variety of electrochemical systems for biomolecule detection, batteries, solar cells, scanning electrochemical microscopy, etc. Given the complexity of the electrode structures, the Butler-Volmer formalism of redox reactions, and the diffusion transport of redox species, it is hardly surprising that only a few problems are amenable to closed form, compact analytical solutions. While numerical solutions are widely used, it is often difficult to integrate the insights gained to the design and optimization of electrochemical systems. In this article, we develop a comprehensive analytical formalism for current transients that not only anticipate the response of complex electrode structures to complicated voltammetry measurements, but also intuitively interpret diverse experiments such as redox detection of molecules at nanogap electrodes, scanning electrochemical microscopy, etc. The results from the analytical model, well supported through detai...
Separator-spacer for electrochemical systems
Grimes, Patrick G.; Einstein, Harry; Newby, Kenneth R.; Bellows, Richard J.
1983-08-02
An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.
Active noise canceling system for mechanically cooled germanium radiation detectors
Nelson, Karl Einar; Burks, Morgan T
2014-04-22
A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.
Stochastic resonance in linear system driven by multiplicative noise and additive quadratic noise
Ning Li-Juan; Xu Wei; Yao Ming-Li
2007-01-01
In this paper the stochastic resonance (SR) is studied in an overdamped linear system driven by multiplicative noise and additive quadratic noise. The exact expressions are obtained for the first two moments and the correlation function by using linear response and the properties of the dichotomous noise. SR phenomenon exhibits in the linear system. There are three different forms of SR: the bona fide SR, the conventional SR and SR in the broad sense.Moreover, the effect of the asymmetry of the multiplicative noise on the signal-to-noise ratio (SNR) is different from that of the additive noise and the effect of multiplicative noise and additive noise on SNR is different.
Noise Induced Switching in Delayed Systems
2012-04-27
Hamiltonian . In many cases, as in general descriptions of finite population interactions [38], it is not possible to use the Lagrangian approach. In the general...the Hamiltonian or Lagrangian formulation will work to describe the trajectory of the switching optimal path. For additive noise, the second order...When considering dynamical systems with isolated feedback mechanisms or coupling devices to connect a network, there always exists a finite time for the
Cuevas-Arteaga, C. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas - UAEM, Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos (Mexico)], E-mail: ccuevas@uaem.mx
2008-03-15
Corrosion performance of HK-40m alloy obtained from electrochemical noise technique and polarization curves during 24 h of exposure in high sulfate (80 mol% Na{sub 2}SO{sub 4}-20 mol% V{sub 2}O{sub 5}) and high vanadate (80 mol% V{sub 2}O{sub 5}-20 mol% Na{sub 2}SO{sub 4}) molten salts at 700deg. C are reported. Electrochemical noise signals were analyzed in the time and frequency domain. A statistical analysis obtaining the resistance noise, the current standard deviation and the localization index are presented as well as the determination of corrosion rates. Corrosion rates were supported by X-ray diffraction analysis of corrosion products and scanning electron microscopy analysis of corroded samples. Results from optical microscope examination of the corroded samples showed that HK-40m alloy suffered inter-granular corrosion when was exposed to the high vanadate salt, whereas exposed to the high sulfate salt, HK-40m corroded through a mixed corrosion process. A corrosion mechanism of HK-40m alloy was obtained together with the corrosion rate, showing the different behavior when exposing the alloy to a high vanadate and high sulfate molten salts.
Automotive active noise control (ANC) system. Jidoshayo active noise control (ANC) system
Hasegawa, S. (Nissan Motor Co. Ltd., Tokyo (Japan))
1992-11-25
This paper introduces a successful development of an active noise control (ANC) system that selects and controls noise in an automobile compartment. This is a system that Nissan has developed for practical use for the first time in the world by using an adaptive control theory and a digital signal processor (DSP) that uses ultra-high speed operating elements. The principle for noise silencing in the ANC system utilizes interference of cyclic amplitude of sound with opposite phase. Sounds in an automobile include informative sounds, agreeable sounds, and noise, and combinations of these sounds work complexly on people in a car, of which extent varies depending on individuals. The adaptive control minimizes sounds picked up by a microphone into controlled speaker sound via an multiple error filtered algorithm (MEF-[sub X]LMS) and an adaptive digital filter. Major components of the system include a microphone, a speaker, and a control unit (comprising the adaptive algorithm and the adaptive filter), all having been developed newly. A DSP that operates on ultra-high speed operating elements was used for speedy compliance with complex algorithms, so that the controlled sound combined of engine noise with compartment sound field can be calculated. The noise was reduced by more than 10 dB at maximum. 7 figs.
Phase Noise Influence in Optical OFDM Systems employing RF Pilot Tone for Phase Noise Cancellation
Jacobsen, Gunnar; Kazovsky, Leonid G.; Xu, TianHua; Popov, Sergei; Li, Jie; Zhang, Yimo; Friberg, Ari T.
2016-01-01
For coherent and direct-detection Orthogonal Frequency Division Multiplexed (OFDM) systems employing radio frequency (RF) pilot tone phase noise cancellation the influence of laser phase noise is evaluated. Novel analytical results for the common phase error and for the (modulation dependent) inter carrier interference are evaluated based upon Gaussian statistics for the laser phase noise. In the evaluation it is accounted for that the laser phase noise is filtered in the correlation signal d...
Rocha, Paulo R. F.; Schlett, Paul; Kintzel, Ulrike; Mailänder, Volker; Vandamme, Lode K. J.; Zeck, Gunther; Gomes, Henrique L.; Biscarini, Fabio; de Leeuw, Dago M.
2016-10-01
Microelectrode arrays (MEA) record extracellular local field potentials of cells adhered to the electrodes. A disadvantage is the limited signal-to-noise ratio. The state-of-the-art background noise level is about 10 μVpp. Furthermore, in MEAs low frequency events are filtered out. Here, we quantitatively analyze Au electrode/electrolyte interfaces with impedance spectroscopy and noise measurements. The equivalent circuit is the charge transfer resistance in parallel with a constant phase element that describes the double layer capacitance, in series with a spreading resistance. This equivalent circuit leads to a Maxwell-Wagner relaxation frequency, the value of which is determined as a function of electrode area and molarity of an aqueous KCl electrolyte solution. The electrochemical voltage and current noise is measured as a function of electrode area and frequency and follow unambiguously from the measured impedance. By using large area electrodes the noise floor can be as low as 0.3 μVpp. The resulting high sensitivity is demonstrated by the extracellular detection of C6 glioma cell populations. Their minute electrical activity can be clearly detected at a frequency below about 10 Hz, which shows that the methodology can be used to monitor slow cooperative biological signals in cell populations.
Van Aken, B.B.; Veldman, D.; Gouwen, R.J.; Bende, E.E.; Eerenstein, W.
2013-10-15
Damp-heat testing of PV modules is a time-consuming process, taking months. The electrochemical noise (EcN) set-up is a fast, direct corrosion measurement of solar cells, whereby results can be obtained within one hour. EcN measurements are presented for several solar cell concepts and different environments. It correlates with damp-heat degradation involving corrosion, which is rather common in EVA-encapsulated crystalline Si modules. Furthermore, the EcN test can be done as an evaluation tool when probing alternative brands, formulations or processing for metallisation pastes and as a screening test for new batches of metallisation paste.
Correlated L\\'evy noise in linear dynamical systems
Srokowski, Tomasz
2010-01-01
Linear dynamical systems, driven by a non-white noise which has the Levy distribution, are analysed. Noise is modelled by a specific stochastic process which is defined by the Langevin equation with a linear force and the Levy distributed symmetric white noise. Correlation properties of the process are discussed. The Fokker-Planck equation driven by that noise is solved. Distributions have the Levy shape and their width, for a given time, is smaller than for processes in the white noise limit...
Analysis and modeling of noise in biomedical systems.
Ranjbaran, Mina; Jalaleddini, Kian; Lopez, Diego Guarin; Kearney, Robert E; Galiana, Henrietta L
2013-01-01
Noise characteristics play an important role in evaluating tools developed to study biomedical systems. Despite usual assumptions, noise in biomedical systems is often nonwhite or non-Gaussian. In this paper, we present a method to analyze the noise component of a biomedical system. We demonstrate the effectiveness of the method in the analysis of noise in voluntary ankle torque measured by a torque transducer and eye movements measured by electro-oculography (EOG).
Hanson, C. E.; Abbot, P.; Dyer, I.
1993-01-01
Noise levels from magnetically-levitated trains (maglev) at very high speed may be high enough to cause environmental noise impact in residential areas. Aeroacoustic sources dominate the sound at high speeds and guideway vibrations generate noticeable sound at low speed. In addition to high noise levels, the startle effect as a result of sudden onset of sound from a rapidly moving nearby maglev vehicle may lead to increased annoyance to neighbors of a maglev system. The report provides a base for determining the noise consequences and potential mitigation for a high speed maglev system in populated areas of the United States. Four areas are included in the study: (1) definition of noise sources; (2) development of noise criteria; (3) development of design guidelines; and (4) recommendations for a noise testing facility.
A new adaptive filtering algorithm for systems with multiplicative noise
WANG Hui-li; CHEN Xi-xin; LU Qian-hao
2005-01-01
Presented here is a new adaptive state filtering algorithm for systems with multiplicative noise. This algorithm estimates the vector state of the system and the statistics of noise when all the statistics of noise are unknown. This filtering algorithm is a simple recursive structure. A simulation example is presented which demonstrates the effectiveness of this filtering algorithm.
Hua-Ming Qian
2014-01-01
Full Text Available A robust filtering problem is formulated and investigated for a class of nonlinear systems with correlated noises, packet losses, and multiplicative noises. The packet losses are assumed to be independent Bernoulli random variables. The multiplicative noises are described as random variables with bounded variance. Different from the traditional robust filter based on the assumption that the process noises are uncorrelated with the measurement noises, the objective of the addressed robust filtering problem is to design a recursive filter such that, for packet losses and multiplicative noises, the state prediction and filtering covariance matrices have the optimized upper bounds in the case that there are correlated process and measurement noises. Two examples are used to illustrate the effectiveness of the proposed filter.
Nan DU; Gang LIU; Qing ZHAO
2008-01-01
The initial pitting behaviors of 30CrMnSi steel in 0.05 mol/L NaCl+0.5 mol/L NaHCO3 solution was studied using electric speckle pattern interferometery (ESPI) and electrochemical noise (EN). Results show that the bright speckles and sharp fluctuation of electrochem-ical signals occurred at the same time. The EN curve shows that there are three stages during the pitting process -- the induction stage (0-50 s), the incubation stage (50-300 s) and the initiative stage (300-512 s).
Multichannel active noise control systems and algorithms for reduction on broadband noise
Berkhoff, A.P.; Wesselink, J.M.
2007-01-01
Active noise contral systems for braadband noise reduction require substantial computing power, especially for multichannel systems and adaptive controllers. Furthermore, speed of convergence can be an issue as weil. In this paper, methods and techniques are described that are able to reduce the com
Studies on mass transfer in electrochemical systems
Sundstroem, L.G.
1997-10-01
The first part is of an introductory nature. It contains a description of the methods used, a discussion of the physics of electrochemical cells with a liquid electrolyte, and a summary of the different studies made, including both those which have been reported in papers, and those which have not. Contributions with novel aspects include (* a derivation of the electro-neutrality condition from Maxwell`s equations of electrodynamics, and **) an argument in favour of the use of mass-averaged velocity in ion transport expressions. The second part focuses on specific cases. It consists of seven research papers which give a more detailed presentation of the main studies 40 refs, 6 figs
Active Aircraft Pylon Noise Control System
Thomas, Russell H. (Inventor); Czech, Michael J. (Inventor); Elmiligui, Alaa A. (Inventor)
2017-01-01
An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.
Flow induced noise modelling for industrial piping systems
Gijrath, H.; Ǎbom, M.
2003-01-01
Noise from e.g. gas-transport piping systems becomes more and more a problem for plants located close to urban areas. Too high noise levels are unacceptable and will put limitations on the plant capacity. Flow-induced noise of valves, orifices and headers installed in the installation plays a domina
Effect of signal modulating noise in bistable stochastic dynamical systems
肖方红; 闫桂荣; 张新武
2003-01-01
The effect of signal modulating noise in bistable stochastic dynamical systems is studied.The concept of instan taneous steady state is proposed for bistable dynamical systems.By making a dynamical analysis of bistable stochastic systems,we find that global and local effect of signal modulating noise as well as stochastic resonance can occur in bistable dynamical systems on which both a weak sinusoidal signal and noise are forced.The effect is demonstrated by numerical simulation.
VARIANCE OF NONLINEAR PHASE NOISE IN FIBER-OPTIC SYSTEM
RANJU KANWAR; SAMEKSHA BHASKAR
2013-01-01
In communication system, the noise process must be known, in order to compute the system performance. The nonlinear effects act as strong perturbation in long- haul system. This perturbation effects the signal, when interact with amplitude noise, and results in random motion of the phase of the signal. Based on the perturbation theory, the variance of nonlinear phase noise contaminated by both self- and cross-phase modulation, is derived analytically for phase-shift- keying system. Through th...
Application of Integer and Fractional Models in Electrochemical Systems
Isabel S. Jesus
2012-01-01
Full Text Available This paper describes the use of integer and fractional electrical elements, for modelling two electrochemical systems. A first type of system consists of botanical elements and a second type is implemented by electrolyte processes with fractal electrodes. Experimental results are analyzed in the frequency domain, and the pros and cons of adopting fractional-order electrical components for modelling these systems are compared.
Noise is all around you, from televisions and radios to lawn mowers and washing machines. Normally, you ... sensitive structures of the inner ear and cause noise-induced hearing loss. More than 30 million Americans ...
Approximation of stochastic equilibria for dynamic systems with colored noise
Bashkirtseva, Irina [Ural Federal University, Lenina 51, Ekaterinburg, 620083 (Russian Federation)
2015-03-10
We consider nonlinear dynamic systems forced by colored noise. Using first approximation systems, we study dynamics of deviations of stochastic solutions from stable deterministic equilibria. Equations for the stationary second moments of deviations of random states are derived. An application of the elaborated theory to Van der Pol system driven by colored noise is given. A dependence of the dispersion on the time correlation of the colored noise is studied.
Quantum noise property in coherent atomic system
ZHANG Jun-xiang; WANG Hai-hong; CAI Jin; GAO Jiang-rui
2006-01-01
The coherent superposition of atomic states leads to the characteristic change of interacting lights because of the coupling between the lights and atoms.In this paper,the noise spectrum of the quantified light interacting with the atoms is studied under the condition of electromagnetically induced transparency (EIT).It is shown that the noise spectrum displays a double M-shape noise profile resulted from the conversion of phase noise of probe beam.A squeezing of 0.3 dB can be observed at the detuning of probe light at the proper parameters of atoms and coupling beam.
Vinod P. Raphael
2016-01-01
Full Text Available A heterocyclic phenylhydrazone 2-[(E-(2-phenylhydrazinylidenemethyl]pyridine (P2APH and its reduced form 2-[(2-phenylhydrazinylmethyl]pyridine (RP2APH were synthesized, characterized, and subjected to corrosion inhibition investigation on carbon steel (CS in 1 M HCl using gravimetric, polarization, electrochemical noise, quantum chemical, and surface studies. P2APH showed more inhibition capacity than RP2PPH. But RP2PPH was very stable in acid medium and showed pronounced corrosion inhibition efficacy for days. Energy of HOMO and LUMO, their difference, number of electrons transferred, electronegativity, chemical hardness, and so forth were evaluated by quantum chemical studies. Agreeable correlation was observed between the results of quantum chemical calculations and other corrosion monitoring techniques.
A compact analytical formalism for current transients in electrochemical systems.
Nair, Pradeep R; Alam, Muhammad A
2013-01-21
Micro- and nanostructured electrodes form an integral part of a wide variety of electrochemical systems for biomolecular detection, batteries, solar cells, scanning electrochemical microscopy, etc. Given the complexity of the electrode structures, the Butler-Volmer formalism of redox reactions, and the diffusion transport of redox species, it is hardly surprising that only a few problems are amenable to closed-form, compact analytical solutions. While numerical solutions are widely used, it is often difficult to integrate the insights gained into the design and optimization of electrochemical systems. In this article, we develop a comprehensive analytical formalism for current transients that not only anticipate the responses of complex electrode structures to complicated voltammetry measurements, but also intuitively interpret diverse experiments such as redox detection of molecules at nanogap electrodes, scanning electrochemical microscopy, etc. The results from the analytical model, well supported through detailed numerical simulations and experimental data from the literature, have broad implications in the design and optimization of nanostructured electrodes for healthcare and energy storage applications.
Hong, Jun; Liu, An-min; Guo, Jian
2013-08-01
An analytic model for an injection-locked dual-loop optoelectronic oscillator (OEO) is proposed and verified by experiments in this paper. Based on this theoretical model, the effect of injection power on the single-sideband phase noise of the OEO is analyzed, and results suggest that moderate injection is one key factor for a balance between phase noise and spur for OEO. In order to measure superlow phase noise of OEOs, a cross-correlation measurement system based on the fiber delay line is built, in which high linear photodetector and low-phase-noise amplifier are used to improve systematic sensitivity. The cross-correlation measurement system is validated by experiments, and its noise floor for the X band is about -130 dBc/Hz at 1 kHz and -168 dBc/Hz at 10 kHz after a cross correlation of 200 times.
Stability of Controlled Hamilton Systems Excited by Gaussian White Noise
SHANG Mei; GUO Yong-xin; MEI Feng-xiang
2008-01-01
A new method is introduced in this paper. This method can be used to study the stability of controlled holonomic Hamilton systems under disturbance of Gaussian white noise. At first, the motion equation of controlled holonomic Hamilton systems excited by Gaussian noise is formulated. A theory to stabilize the system is provided. Finally, one example is given to illustrate the application procedures.
System Driven by Correlated Gaussian Noises Related with Disorder
LI Jing-Hui
2007-01-01
A system driven by correlated Gaussian noises related with disorder is investigated. The Fokker-Planck equation (FPE) for the system is derived. Using the FPE derived, some systems driven by correlated Gaussian noises related with disorder can be investigated for Brownian motors, nonequilibrium transition, resonant activation,stochastic resonance, and so on. We only give one example: i.e., using the FPE derived, we study the resonant activation for a single motor protein model with correlated noises related to disorder. Since the correlated noise related to disorder usually exists with the friction, for the temperature, and so on, our results have generic physical meanings for physics, chemistry, biology and other sciences.
Noise-Induced Voltage Collapse in Power Systems
WEI Du-Qu; LUO Xiao-Shu; ZHANG Bo
2012-01-01
We investigate numerically the influences of Gaussian white noise on the dynamical behaviors of power systems.The studied model is a three-bus system at some specific parameters,and it demonstrates a stable regime that is far from collapse.It is found that with the increasing noise intensity σ,power systems become unstable and fall into oscillations; as σ is further increased,noise-induced voltage collapse in power systems takes place.Our results confirm that the presence of noise has a detrimental effect on power system operation.Furthermore,the possible mechanism behind the action of noise is addressed based on a dynamical approach where the bifurcation of the system is analyzed.Our results may provide useful information for avoiding instability problems in power systems.
Gering, Kevin L
2013-08-27
A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware periodically samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics of the electrochemical cell. The computing system also develops a mechanistic level model of the electrochemical cell to determine performance fade characteristics of the electrochemical cell and analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell. The mechanistic level model uses first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density. The mechanistic level model also is based on second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density.
Vibration and noise analysis of a gear transmission system
Choy, F. K.; Qian, W.; Zakrajsek, J. J.; Oswald, F. B.
1993-01-01
This paper presents a comprehensive procedure to predict both the vibration and noise generated by a gear transmission system under normal operating conditions. The gearbox vibrations were obtained from both numerical simulation and experimental studies using a gear noise test rig. In addition, the noise generated by the gearbox vibrations was recorded during the experimental testing. A numerical method was used to develop linear relationships between the gearbox vibration and the generated noise. The hypercoherence function is introduced to correlate the nonlinear relationship between the fundamental noise frequency and its harmonics. A numerical procedure was developed using both the linear and nonlinear relationships generated from the experimental data to predict noise resulting from the gearbox vibrations. The application of this methodology is demonstrated by comparing the numerical and experimental results from the gear noise test rig.
Phase Noise Influence in Optical OFDM Systems employing RF Pilot Tone for Phase Noise Cancellation
Jacobsen, Gunnar; Kazovsky, Leonid G.; Xu, Tianhua; Popov, Sergei; Li, Jie; Zhang, Yima; Friberg, Ari T.
2011-06-01
For coherent and direct-detection Orthogonal Frequency Division Multiplexed (OFDM) systems employing radio frequency (RF) pilot tone phase noise cancellation the influence of laser phase noise is evaluated. Novel analytical results for the common phase error and for the (modulation dependent) inter carrier interference are evaluated based upon Gaussian statistics for the laser phase noise. In the evaluation it is accounted for that the laser phase noise is filtered in the correlation signal detection. Numerical results are presented for OFDM systems with 4 and 16 PSK modulation, 200 OFDM bins and baud rate of 1 GS/s. It is found that about 225 km transmission is feasible for the coherent 4PSK-OFDM system over normal (G.652) fiber.
Phase Noise Influence in Optical OFDM Systems employing RF Pilot Tone for Phase Noise Cancellation
Jacobsen, Gunnar; Xu, Tianhua; Popov, Sergei; Li, Jie; Zhang, Yimo; Friberg, Ari T
2016-01-01
For coherent and direct-detection Orthogonal Frequency Division Multiplexed (OFDM) systems employing radio frequency (RF) pilot tone phase noise cancellation the influence of laser phase noise is evaluated. Novel analytical results for the common phase error and for the (modulation dependent) inter carrier interference are evaluated based upon Gaussian statistics for the laser phase noise. In the evaluation it is accounted for that the laser phase noise is filtered in the correlation signal detection. Numerical results are presented for OFDM systems with 4 and 16 PSK modulation, 200 OFDM bins and baud rate of 1 GS/s. It is found that about 225 km transmission is feasible for the coherent 4PSK-OFDM system over normal (G.652) fiber.
Fluctuating Potential Barrier System with Correlated Spatial Noises
LI Jing-Hui
2004-01-01
In this paper, we study a fluctuating potential barrier system with correlated spatial noises. Study shows that for this system, there is the resonant activation over the fluctuating potential barrier, and that the correlation between the different spatial noises can enhance (or weaken) the resonant activation.
Effect of phase noise in an OFDM／OQAM system
ChenQifan; WuBingyang; ChengShixin
2003-01-01
The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation of OFDM/OQAM is first derived with the square root raised cosine (SRRC) filter as the pulse-shaping filter. Then the effect of multiplicative phase noise is equivalently represented as additive white Gaussian noise (AWGN), the variance of which is given analytically. We can observe that the same result as OFDM/QAM system is derived. Lastly, all the analytical results are verified by the bit error rate (BER) degradation through Monte Carlo simulation.
Radar signature acquisition using an indigenously designed noise radar system
Freundorfer, A. P.; Siddiqui, J. Y.; Antar, Y. M. M.; Thayaparan, T.
2011-06-01
A new design of a noise radar system is proposed with capabilities to measure and acquire the radar signature of various targets. The proposed system can cover a noise bandwidth of near DC to 30 GHz. The noise radar signature measurements were conducted for selective targets like spheres and carpenter squares with and without dielectric bodies for a noise band of 400MHz-3000MHz. The bandwidth of operation was limited by the multiplier and the antennae used. The measured results of the target signatures were verified with the simulation results.
Nonlinear phase noise in coherent optical OFDM transmission systems.
Zhu, Xianming; Kumar, Shiva
2010-03-29
We derive an analytical formula to estimate the variance of nonlinear phase noise caused by the interaction of amplified spontaneous emission (ASE) noise with fiber nonlinearity such as self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in coherent orthogonal frequency division multiplexing (OFDM) systems. The analytical results agree very well with numerical simulations, enabling the study of the nonlinear penalties in long-haul coherent OFDM systems without extensive numerical simulation. Our results show that the nonlinear phase noise induced by FWM is significantly larger than that induced by SPM and XPM, which is in contrast to traditional WDM systems where ASE-FWM interaction is negligible in quasi-linear systems. We also found that fiber chromatic dispersion can reduce the nonlinear phase noise. The variance of the total phase noise increases linearly with the bit rate, and does not depend significantly on the number of subcarriers for systems with moderate fiber chromatic dispersion.
Noise properties of graphene like systems
Rustagi, Avinash; Stanton, C. J.
2013-03-01
The unusual electronic properties of graphene and its potential for applications in nanoscale devices motivated us to study the noise properties of materials that have a graphene-like electronic dispersion. For high values of electric field, we find interesting behavior in the noise properties which appear due to hot electron effects. We study the low-frequency noise based on the Boltzmann-Green function method within the relaxation time approximation considering an inelastic scattering term coming from phonon scattering and an elastic scattering term coming from impurity scattering. The steady-state distribution function is evaluated to calculate the average behavior of physical observables like current and energy. We find that as the field strength is increased, the noise decreases from the thermal noise value. We have also studied these properties for electronic dispersion with a gap parameter introduced in the Dirac spectrum. The inclusion of gap in the electronic dispersion causes initial heating of the electrons resulting in an increase in noise for intermediate values of field before it decreases at high fields. Supported by NSF through grants OISE-0968405.
Modular software-controlled electrochemical system
Hagan, D.; Spivey, J.; Niculescu, V. A.
1987-03-01
A modular microcomputer-controlled three-electrode potentiostat configured with graphics is presented. The system is designed for metallic surface characterization and is capable of performing in different modes of operation including single sweep voltammetry, cyclic voltammetry, and chronoamperometry. An integrated and flexible software system for control, data taking, data storage, and transfer is described. Data analysis software for the IBM-PC computer including two- and three-dimensional plotting as well as menu-driven theoretical modeling, simulation, and curvefitting has been developed.
Lithium batteries and other electrochemical storage systems
Glaize, Christian
2013-01-01
Lithium batteries were introduced relatively recently in comparison to lead- or nickel-based batteries, which have been around for over 100 years. Nevertheless, in the space of 20 years, they have acquired a considerable market share - particularly for the supply of mobile devices. We are still a long way from exhausting the possibilities that they offer. Numerous projects will undoubtedly further improve their performances in the years to come. For large-scale storage systems, other types of batteries are also worthy of consideration: hot batteries and redox flow systems, for example.
Robust consensus of multi-agent systems with noise
WANG Lin; LIU ZhiXin
2009-01-01
The consensus problem of multi-agent systems has attracted wide attention from researchers in recent years, following the initial work of Jadbabaie et al. on the analysis of a simplified Vicsek model. While the original Vicsek model contains noise effects, almost all the existing theoretical results on consensus problem, however, do not take the noise effects into account. The purpose of this paper is to initiate a study of the consensus problems under noise disturbances. First, the class of multi-agent systems under study is transformed into a general time-varying system with noise. Then, for such a system, the equivalent relationships are established among (ⅰ) robust consensus, (ⅱ) the positivity of the second smallest eigenvalue of a weighted Laplacian matrix, and (ⅲ) the joint connectivity of the associated dynamical neighbor graphs. Finally, this basic equivalence result is shown to be applicable to several classes of concrete multi-agent models with noise.
Electrochemical system including lamella settler crystallizer
Maimoni, Arturo
1988-01-01
A crystallizer which incorporates a lamella settler and which is particularly applicable for use in batteries and power cells for electric vehicles or stationary applications. The lamella settler can be utilized for coarse particle separation or for agglomeration, and is particularly applicable to aluminum-air batteries or power cells for solving the hydrargillite (aluminum-hydroxide) removal problems from such batteries. This invention provides the advantages of very low energy consumption, turbulence, shear, cost and maintenance. Thus, due to the low shear and low turbulence of this invention, it is particularly effective in the control of aluminum hydroxide particle size distribution in the various sections of an aluminum-air system, as will as in other elecrochemical systems requiring separation for phases of different densities.
Exploratory studies on some electrochemical cell systems
Chaudhuri, Srikumar; Guha, D.
Exploratory studies were conducted on cell systems with different metal anodes, and iodine and sulphur mixed with graphite powder in a polymer matrix as cathodes, using different electrolytes in non-aqueous and aqueous media as ionic charge carriers. The electrical conductance of the electrolyte solutions in aqueous and non-aqueous solvents, the open circuit voltage (OCV) and short circuit current (SCC) for the different cell systems were measured. To date, the non-aqueous solvents used in our studies were dimethylformamide, formamide, dioxan, and nitrobenzene, and the electrolytes used were potassium iodide, caustic potash, cetyltrimethylammonium bromide (CTAB), sodium lauryl sulphate (SLS) and calcium chloride. These electrolytes were used in both non-aqueous and aqueous media. In general, aqueous electrolyte solutions gave a better performance than non-aqueous electrolyte solutions. Of the aqueous electrolytes, the highest conductance was shown by potassium chloride solution in water (conductance=0.0334 mho). However, the best OCV and SCC were shown by aluminium as anode and iodine as cathode with a saturated solution of caustic potash in water. The OCV was 1.85 V and the SCC was 290 mA cm -2. The highest conductance among the non-aqueous systems was shown by caustic potash in formamide. (Conductance=0.013 mho.) The best OCV and SCC, however, were shown by a zinc anode and iodine cathode with saturated potassium chloride in formamide, having an OCV of 1.55 V and an SCC of 150 mA cm -2. Further studies are in progress to obtain detailed performance data and recharging characteristics of some of the more promising systems reported here.
Methods for Stability and Noise Analysis of Coupled Oscillating Systems
Djurhuus, Torsten
2008-01-01
and phase-noise filters; to name but a few of the possible applications areas. Taking outset in the established single-oscillator phase-macro model, a novel numerical algorithm for the automated phase-noise characterization of coupled oscillators, perturbed by noise, is developed. The algorithm, which......In this thesis a study of analytical and numerical models of coupled oscillating systems, perturbed by delta-correlated noise sources, is undertaken. These models are important for the attainment of a qualitative understanding of the complex dynamics seen in various physical, biological, electronic...
Perception Neural Networks for Active Noise Control Systems
Wang Xiaoli
2012-11-01
Full Text Available In a response to a growing demand for environments of 70dB or less noise levels, many industrial sectors have focused with some form of noise control system. Active noise control (ANC has proven to be the most effective technology. This paper mainly investigates application of neural network on self-adaptation system in active noise control (ANC. An active silencing control system is made which adopts a motional feedback loudspeaker as not a noise controlling source but a detecting sensor. The working fundamentals and the characteristics of the motional feedback loudspeaker are analyzed in detail. By analyzing each acoustical path, identification based adaptive linear neural network is built. This kind of identifying method can be achieved conveniently. The estimated result of each sound channel matches well with its real sound character, respectively.
Transport for a System with Additive Temporal-Spatial Noise
LI Jing-Hui; HAN Yin-Xia; CHEN Shi-Gang
2004-01-01
In this paper, we study the transport of the system with the additive temporal-spatial noise, by two models, i.e., a spatial asymmetry model and a spatial symmetry model. The study shows that the correlation of the additive noise with the space and the spatial asymmetry are ingredients for the transport.
Environmental Noise and Nonlinear Relaxation in Biological Systems
Spagnolo, B; Spezia, S; Curcio, L; Pizzolato, N; Dubkov, A A; Fiasconaro, A; Adorno, D Persano; Bue, P Lo; Peri, E; Colazza, S
2011-01-01
We analyse the effects of environmental noise in three different biological systems: (i) mating behaviour of individuals of \\emph{Nezara viridula} (L.) (Heteroptera Pentatomidae); (ii) polymer translocation in crowded solution; (iii) an ecosystem described by a Verhulst model with a multiplicative L\\'{e}vy noise.
Superlinearly scalable noise robustness of redundant coupled dynamical systems.
Kohar, Vivek; Kia, Behnam; Lindner, John F; Ditto, William L
2016-03-01
We illustrate through theory and numerical simulations that redundant coupled dynamical systems can be extremely robust against local noise in comparison to uncoupled dynamical systems evolving in the same noisy environment. Previous studies have shown that the noise robustness of redundant coupled dynamical systems is linearly scalable and deviations due to noise can be minimized by increasing the number of coupled units. Here, we demonstrate that the noise robustness can actually be scaled superlinearly if some conditions are met and very high noise robustness can be realized with very few coupled units. We discuss these conditions and show that this superlinear scalability depends on the nonlinearity of the individual dynamical units. The phenomenon is demonstrated in discrete as well as continuous dynamical systems. This superlinear scalability not only provides us an opportunity to exploit the nonlinearity of physical systems without being bogged down by noise but may also help us in understanding the functional role of coupled redundancy found in many biological systems. Moreover, engineers can exploit superlinear noise suppression by starting a coupled system near (not necessarily at) the appropriate initial condition.
Current-potential characteristics of electrochemical systems
Battaglia, V.S.
1993-07-01
This dissertation contains investigations in three distinct areas. Chapters 1 and 2 provide an analysis of the effects of electromagnetic phenomena during the initial stages of cell discharge. Chapter 1 includes the solution to Maxwell`s equations for the penetration of the axial component of an electric field into an infinitely long cylindrical conductor. Chapter 2 contains the analysis of the conductor included in a radial circuit. Chapter 3 provides a complete description of the equations that describe the growth of an oxide film. A finite difference program was written to solve the equations. The system investigated is the iron/iron oxide in a basic, aqueous solution. Chapters 4 and 5 include the experimental attempts for replacing formaldehyde with an innocuous reducing agent for electroless deposition. In chapter 4, current-versus-voltage curves are provided for a sodium thiosulfate bath in the presence of a copper disk electrode. Also provided are the cathodic polarization curves of a copper/EDTA bath in the presence of a copper electrode. Chapter 5 contains the experimental results of work done with sodium hypophosphite as a reducing agent. Mixed-potential-versus-time curves for solutions containing various combinations of copper sulfate, nickel chloride, and hypophosphite in the presence of a palladium disk electrode provide an indication of the reducing power of the solutions.
Electrochemical decontamination system for actinide processing gloveboxes
Wedman, D.E.; Lugo, J.L.; Ford, D.K.; Nelson, T.O.; Trujillo, V.L.; Martinez, H.E.
1998-03-01
An electrolytic decontamination technology has been developed and successfully demonstrated at Los Alamos National Laboratory (LANL) for the decontamination of actinide processing gloveboxes. The technique decontaminates the interior surfaces of stainless steel gloveboxes utilizing a process similar to electropolishing. The decontamination device is compact and transportable allowing it to be placed entirely within the glovebox line. In this way, decontamination does not require the operator to wear any additional personal protective equipment and there is no need for additional air handling or containment systems. Decontamination prior to glovebox decommissioning reduces the potential for worker exposure and environmental releases during the decommissioning, transport, and size reduction procedures which follow. The goal of this effort is to reduce contamination levels of alpha emitting nuclides for a resultant reduction in waste level category from High Level Transuranic (TRU) to low Specific Activity (LSA, less than or equal 100 nCi/g). This reduction in category results in a 95% reduction in disposal and disposition costs for the decontaminated gloveboxes. The resulting contamination levels following decontamination by this method are generally five orders of magnitude below the LSA specification. Additionally, the sodium sulfate based electrolyte utilized in the process is fully recyclable which results in the minimum of secondary waste. The process bas been implemented on seven gloveboxes within LANL`s Plutonium Facility at Technical Area 55. Of these gloveboxes, two have been discarded as low level waste items and the remaining five have been reused.
Renslow, R S; Babauta, J T; Majors, P D; Mehta, H S; Ewing, R J; Ewing, T W; Mueller, K T; Beyenal, H
2014-01-01
Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for noninvasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live biofilms respiring on electrodes. Here, we describe a biofilm microreactor system, including a reusable and a disposable reactor, that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radio frequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system we grew Geobacter sulfurreducens biofilms on electrodes. EC-NMR was used to investigate growth medium flow velocities and depth-resolved acetate concentration inside the biofilm. As a novel contribution we used Monte Carlo error analysis to estimate the standard deviations of the acetate concentration measurements. Overall, we found that the disposable EC-NMR microreactor provided a 9.7 times better signal-to-noise ratio over the reusable reactor. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.
VARIANCE OF NONLINEAR PHASE NOISE IN FIBER-OPTIC SYSTEM
RANJU KANWAR
2013-04-01
Full Text Available In communication system, the noise process must be known, in order to compute the system performance. The nonlinear effects act as strong perturbation in long- haul system. This perturbation effects the signal, when interact with amplitude noise, and results in random motion of the phase of the signal. Based on the perturbation theory, the variance of nonlinear phase noise contaminated by both self- and cross-phase modulation, is derived analytically for phase-shift- keying system. Through this work, it is investigated that for longer transmission distance, 40-Gb/s systems are more sensitive to nonlinear phase noise as compared to 50-Gb/s systems. Also, when transmitting the data through the fiber optic link, bit errors are produced due to various effects such as noise from optical amplifiers and nonlinearity occurring in fiber. On the basis of the simulation results , we have compared the bit error rate based on 8-PSK with theoretical results, and result shows that in real time approach, the bit error rate is high for the same signal to noise ratio. MATLAB software is used to validate the analytical expressions for the variance of nonlinear phase noise.
Noise-Induced Subdiffusion in Strongly Localized Quantum Systems
Gopalakrishnan, Sarang; Islam, K. Ranjibul; Knap, Michael
2017-07-01
We consider the dynamics of strongly localized systems subject to dephasing noise with arbitrary correlation time. Although noise inevitably induces delocalization, transport in the noise-induced delocalized phase is subdiffusive in a parametrically large intermediate-time window. We argue for this intermediate-time subdiffusive regime both analytically and using numerical simulations on single-particle localized systems. Furthermore, we show that normal diffusion is restored in the long-time limit, through processes analogous to variable-range hopping. With numerical simulations based on Lanczos exact diagonalization, we demonstrate that our qualitative conclusions are also valid for interacting systems in the many-body localized phase.
Turbo Receiver Design for Phase Noise Mitigation in OFDM Systems
Sridharan, Gokul
2010-01-01
This paper addresses the issue of phase noise in OFDM systems. Phase noise (PHN) is a transceiver impairment resulting from the non-idealities of the local oscillator. We present a case for designing a turbo receiver for systems corrupted by phase noise by taking a closer look at the effects of the common phase error (CPE). Using an approximate probabilistic framework called variational inference (VI), we develop a soft-in soft-out (SISO) algorithm that generates posterior bit-level soft estimates while taking into account the effect of phase noise. The algorithm also provides an estimate of the phase noise sequence. Using this SISO algorithm, a turbo receiver is designed by passing soft information between the SISO detector and an outer forward error correcting (FEC) decoder that uses a soft decoding algorithm. It is shown that the turbo receiver achieves close to optimal performance.
Pulse-noise approach for classical spin systems
Garanin, D A
2016-01-01
For systems of classical spins interacting with the bath via damping and thermal noise, the approach is suggested to replace the white noise by a pulse noise acting at regular time intervals $\\Delta t$, within which the system evolves conservatively. The method is working well in the typical underdamped case $\\lambda\\ll1$ and allows a considerable speed-up of computations by using high-order numerical integrators with a large time step $\\delta t$ in most cases when spin precession is important, while keeping $\\delta t\\ll\\Delta t$ to reduce the relative contribution of noise-related operations. In cases when precession can be discarded, one can choose $\\delta t\\propto1/\\lambda$ that leads to a further speed-up, making equilibration speed comparable with that of Metropolis Monte Carlo. The pulse-noise approach is tested on single-spin and multi-spin models.
Numerical evaluation of the performance of active noise control systems
Mollo, C. G.; Bernhard, R. J.
1990-01-01
This paper presents a generalized numerical technique for evaluating the optimal performance of active noise controllers. In this technique, the indirect BEM numerical procedures are used to derive the active noise controllers for optimal control of enclosed harmonic sound fields where the strength of the noise sources or the description of the enclosure boundary may not be known. The performance prediction for a single-input single-output system is presented, together with the analysis of the stability and observability of an active noise-control system employing detectors. The numerical procedures presented can be used for the design of both the physical configuration and the electronic components of the optimal active noise controller.
Pujar, M.G., E-mail: pujar55@gmail.com [Metallurgy and Materials Group (MMG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Das, C.R.; Thirunavukkarasu, S.; Kamachi Mudali, U.; Bhaduri, A.K. [Metallurgy and Materials Group (MMG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Brijitta, J.; Tata, B.V.R. [Materials Science Group (MSG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India)
2011-10-17
Highlights: {yields} Weibull probability plots separate pitting and passive corrosion events. {yields} Gumbel distribution analysis gives maximum metastable pit depths. {yields} Addition of boron results in superior pitting corrosion resistance in 0.1 M NaCl. {yields} Incorporation of B into M{sub 23}C{sub 6} carbides refines them and improves pitting resistance. {yields} Coarse M{sub 23}C{sub 6} carbides and delta-ferrite result in inferior pitting resistance. - Abstract: 9Cr-1Mo steels indigenously melted with the addition of boron (Alloy B) and without it (Alloy D) along with Alloy C (without boron addition with minor changes in the trace element concentrations) were studied for their pitting corrosion resistance in 0.001 M, 0.01 M, 0.05 M and 0.1 M sodium chloride solutions using electrochemical noise (EN) technique. Weibull probability plots were used to determine the pit embryo generation rates. Gumbel extreme value analysis was conducted to determine the maximum metastable as well as stable pit radii. The analysis of the data showed superior pitting corrosion resistance of the Alloy B compared to Alloy C as well as Alloy D.
Kim, Dong Jin; Kim, Joung Soo; Kim, Hong Pyo; Lim, Yun Soo; Yi, Yong Sun; Chung, Man Kyo
2003-02-01
The studies for the application of electrochemical noise technique were reviewed in terms of principle, analysing method and application examples of this technique. Because 4% of the economic damage of industry is caused by metallic corrosion, it is important to find and protect corrosive materials and location. By corrosion monitoring of industrial facilities such as nuclear power plant using Electrochemical Noise Measurement(ENM), corrosion attack can be detected and furthermore it can be indicated whether the attacked materials is replaced by new one or not. According to development of control and electronic technology, it was easy to apply ENM to the industry and the interest in ENM also increased. As corrosion is produced on a metal under corrosive environment, local anode(oxidation) and cathode(reduction) are formed. Hence, there is potential difference and current flow between the anode and cathode. ENM is monitoring the potential difference and the current flow with time by high impedance load voltmeter and Zero Resistance Ammeter(ZRA), respectively. The potential difference and current flow generated spontaneously without any application of current and potential between electrodes are monitored by electrochemical noise technique, Thereby ENM can be regarded as the most ideal corrosion monitoring method for the industrial facility and nuclear power plant having corrosion damage and difficulty in access of human body. Moreover, it is possible to obtain the spontaneous and reliable results from the metals damaged by ununiform and localized corrosion such as pitting and SCC using ENM while it is difficult to obtain the reliable result using traditional linear polarization and ac-impedance measurement. In many countries, there are extensive works concerned with application of electrochemical noise technique to corrosion monitoring of nuclear power plant and other industrial facilities, whereas there is little work on this field in Korea. Systematic study for
Ramezanzadeh, B.; Arman, S. Y.; Mehdipour, M.; Markhali, B. P.
2014-01-01
In this study, the corrosion inhibition properties of two similar heterocyclic compounds namely benzotriazole (BTA) and benzothiazole (BNS) inhibitors on copper in 1.0 M H2SO4 solution were studied by electrochemical techniques as well as surface analysis. The results showed that corrosion inhibition of copper largely depends on the molecular structure and concentration of the inhibitors. The effect of DC trend on the interpretation of electrochemical noise (ECN) results in time domain was evaluated by moving average removal (MAR) method. Accordingly, the impact of square and Hanning window functions as drift removal methods in frequency domain was studied. After DC trend removal, a good trend was observed between electrochemical noise (ECN) data and the results obtained from EIS and potentiodynamic polarization. Furthermore, the shot noise theory in frequency domain was applied to approach the charge of each electrochemical event (q) from the potential and current noise signals.
Carminati, Marco; Ferrari, Giorgio; Sampietro, Marco
2009-12-01
We present an instrument that enables electrochemical measurements (cyclic voltammetry, impedance tracking, and impedance spectroscopy) on submicrometric samples. The system features a frequency range from dc to 1 MHz and a current resolution of 10 fA for a measurement time of 1 s, giving a sensitivity of few attofarads in terms of measurable capacitance with an applied voltage of only 100 mV. These performances are obtained using a low-noise wide-bandwidth integrator/differentiator stage to sense the input current and a modular approach to minimize the effect of input stray capacitances. A digitally implemented lock-in filter optimally extracts the impedance of the sample, providing time tracking and spectroscopy operating modes. This computer-based and flexible instrument is well suited for characterizing and tracking the electrical properties of biomolecules kept in the physiological solution down to the nanoscale.
Noise control zone for a periodic ducted Helmholtz resonator system.
Cai, Chenzhi; Mak, Cheuk Ming
2016-12-01
This paper presents a theoretical study of the dispersion characteristics of sound wave propagation in a periodic ducted Helmholtz resonator (HR) system. The predicted result fits well with a numerical simulation using a finite element method. This study indicates that for the same system, no matter how many HRs are connected or what the periodic distance is, the area under average transmission loss T L¯ curves is always the same. The broader the noise attenuation band, the lower the peak attenuation amplitude. A noise control zone compromising the attenuation bandwidth or peak amplitude is proposed for noise control optimization.
Noise-induced striped trajectories of Rossler systems
Huang Zhi-hua; Dong Ya-Li
2007-01-01
In the paper,the generation of striped trajectories in phase space by noise-injection is considered. With suitable amplitudes of noise,the steady-state system orbits appear in rectangular striped shape.The relationship between the shape(including the range and the number of stripes)and some parameters is discussed.The result shows that noise can also generate the striped shape effectively and simply,which is similar to the newly-discovered striped pattern generated by controlled Rossler systems.
Liu, Xingbo [West Virginia Univ., Morgantown, WV (United States)
2015-06-30
The key innovation of this project is the synergy of the high temperature sensor technology based on the science of electrochemical measurement and state-of-the-art wireless communication technology. A novel self-powered wireless high temperature electrochemical sensor system has been developed for coal-fired boilers used for power generation. An initial prototype of the in-situ sensor demonstrated the capability of the wireless communication system in the laboratory and in a pilot plant (Industrial USC Boiler Setting) environment to acquire electrochemical potential and current signals during the corrosion process. Uniform and localized under-coal ash deposit corrosion behavior of Inconel 740 superalloy has been studied at different simulated coal ash hot corrosion environments using the developed sensor. Two typical potential noise patterns were found to correlate with the oxidation and sulfidation stages in the hot coal ash corrosion process. Two characteristic current noise patterns indicate the extent of the corrosion. There was a good correlation between the responses of electrochemical test data and the results from corroded surface analysis. Wireless electrochemical potential and current noise signals from a simulated coal ash hot corrosion process were concurrently transmitted and recorded. The results from the performance evaluation of the sensor confirm a high accuracy in the thermodynamic and kinetic response represented by the electrochemical noise and impedance test data.
Hysteretic behavior of spin-crossover noise driven system
Gudyma, Iurii [Department of General Physics, Chernivtsi National University, Chernivtsi 58012 (Ukraine); Maksymov, Artur, E-mail: maxyartur@gmail.com [Department of General Physics, Chernivtsi National University, Chernivtsi 58012 (Ukraine); Advanced Materials Research Institute, University of New Orleans, LA 70148 (United States); Dimian, Mihai [Department of Electrical and Computer Engineering, Howard University, Washington DC, 20059 (United States); Faculty of Electrical Engineering and Computer Science, Stefan cel Mare University, Suceava 720229 (Romania)
2016-04-01
The influence of white Gaussian noise on hysteretic behavior of spin-crossover system is analyzed in the framework of stochastic Langevin dynamics. Various stochastic simulations are performed and several important properties of spin-transition in spin-crossover system driven by noise are reproduced. The numerical results are tested against the stationary probability function and the associated dynamic potential obtained from Fokker–Planck equation corresponding to spin-crossover Langevin dynamics. The dependence of light-induced optical hysteresis width and non-hysteretic transition curve slope on the noise intensity is illustrated. The role of low-spin and high-spin phase stabilities in the hysteretic behavior of noise-driven spin-crossover system is discussed.
Analysis of bilinear stochastic systems. [involving multiplicative noise processes
Willsky, A. S.; Marcus, S. I.; Martin, D. N.
1974-01-01
Analysis of stochastic dynamical systems that involve multiplicative (bilinear) noise processes is considered. After defining the systems of interest, the evolution of the moments of such systems, the question of stochastic stability, and estimation for bilinear stochastic systems are discussed. Both exact and approximate methods of analysis are introduced, and, in particular, the uses of Lie-theoretic concepts and harmonic analysis are discussed.
Gering, Kevin L.
2013-06-18
A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware periodically samples charge characteristics of the electrochemical cell. The computing system periodically determines cell information from the charge characteristics of the electrochemical cell. The computing system also periodically adds a first degradation characteristic from the cell information to a first sigmoid expression, periodically adds a second degradation characteristic from the cell information to a second sigmoid expression and combines the first sigmoid expression and the second sigmoid expression to develop or augment a multiple sigmoid model (MSM) of the electrochemical cell. The MSM may be used to estimate a capacity loss of the electrochemical cell at a desired point in time and analyze other characteristics of the electrochemical cell. The first and second degradation characteristics may be loss of active host sites and loss of free lithium for Li-ion cells.
Stochastic systems driven by alpha-stable noises
Ditlevsen, Ove Dalager; Ditlevsen, P.
1998-01-01
It has almost become a standard in stochastic mechanics applications of stochasticdifferential equations that the driving forces are modeled as Gaussian white noises, that is, as scalar or vector Brownianmotion increments.However, this modeling may not always lead to responses that comply well...... with observed data. In particular the tailsof the observed response distributions may even for linear systems be more fat than the tails obtained for Gaussianwhite noise input. Also the excitation may show jumps that cannot be modeled by Gaussian white noise. The paper supports the possibility of using...
Noise-induced transition in a quantum system
Ghosh, Pulak Kumar [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Barik, Debashis [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Ray, Deb Shankar [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)]. E-mail: pcdsr@mahendra.iacs.res.in
2005-07-04
We examine the noise-induced transition in a fluctuating bistable potential of a driven quantum system in thermal equilibrium. Making use of a Wigner canonical thermal distribution for description of the statistical properties of the thermal bath, we explore the generic effects of quantization like vacuum field fluctuation and tunneling in the characteristic stationary probability distribution functions undergoing transition from unimodal to bimodal nature and in signal-to-noise ratio characterizing the cooperative effect among the noise processes and the weak periodic signal.
Control of noise - systems for compact HVAC units
Pedersen, Steffen; Møller, Henrik
2012-01-01
This paper discusses noise control systems for implementation in compact HVAC units. The control of low-frequency noise presents different problems than at higher frequencies. This is mainly related to the long wavelength, which means that passive solutions require a significant volume of space......, often not available in compact HVAC units. Active control can provide attenuation over a significant frequency range, including low frequencies, while requiring a more limited space. While the concept of active noise control is simple, a number of limitations in the acoustical, electrical and control...... systems affect the performance of implementations. The source pressure and the impedance of a centrifugal fan were measured, and a number of configurations for noise control were investigated. The performance of a simple analogue feedback control was tested in a physical prototype. An adaptive digital...
Noise-enhanced phase synchronization in time-delayed systems.
Senthilkumar, D V; Shrii, M Manju; Kurths, J
2012-02-01
We investigate the phenomenon of noise-enhanced phase synchronization (PS) in coupled time-delay systems, which usually exhibit non-phase-coherent attractors with complex topological properties. As a delay system is essentially an infinite dimensional in nature with multiple characteristic time scales, it is interesting and crucial to understand the interplay of noise and the time scales in achieving PS. In unidirectionally coupled systems, the response system adjust all its time scales to that of the drive, whereas both subsystems adjust their rhythms to a single (main time scale of the uncoupled system) time scale in bidirectionally coupled systems. We find similar effects for both a common and an independent additive Gaussian noise.
Noise Measurements of High Aspect Ratio Distributed Exhaust Systems
Bridges, James E.
2015-01-01
This paper covers far-field acoustic measurements of a family of rectangular nozzles with aspect ratio 8, in the high subsonic flow regime. Several variations of nozzle geometry, commonly found in embedded exhaust systems, are explored, including bevels, slants, single broad chevrons and notches, and internal septae. Far-field acoustic results, presented previously for the simple rectangular nozzle, showed that increasing aspect ratio increases the high frequency noise, especially directed in the plane containing the minor axis of the nozzle. Detailed changes to the nozzle geometry generally made little difference in the noise, and the differences were greatest at low speed. Having an extended lip on one broad side (bevel) did produce up to 3 decibels more noise in all directions, while extending the lip on the narrow side (slant) produced up to 2 decibels more noise, primarily on the side with the extension. Adding a single, non-intrusive chevron, made no significant change to the noise, while inverting the chevron (notch) produced up to 2decibels increase in the noise. Having internal walls (septae) within the nozzle, such as would be required for structural support or when multiple fan ducts are aggregated, reduced the noise of the rectangular jet, but could produce a highly directional shedding tone from the septae trailing edges. Finally, a nozzle with both septae and a beveled nozzle, representative of the exhaust system envisioned for a distributed electric propulsion aircraft with a common rectangular duct, produced almost as much noise as the beveled nozzle, with the septae not contributing much reduction in noise.
Doppler visibility of coherent random noise radar systems
Li, Zhixi; Narayanan, Ram M.
2005-05-01
Random noise radar has recently been used in a variety of imaging and surveillance applications. These systems can be made phase coherent using the technique of heterodyne correlation. Phase coherence has been exploited to measure Doppler and thereby the velocity of moving targets. The Doppler visibility, i.e., the ability to extract Doppler information over the inherent clutter spectra, is constrained by system parameters, especially the phase noise generated by microwave components. Our paper proposes a new phase noise model for the heterodyne mixer as applicable for ultrawideband (UWB) random noise radar and for the local oscillator in the time domain. The Doppler spectra are simulated by including phase noise contamination effects and compared to our previous experimental results. A Genetic Algorithm (GA) optimization routine is applied to synthesize the effects of a variety of parameter combinations to derive a suitable empirical formula for estimating the Doppler visibility in dB. According to the phase noise analysis and the simulation results, the Doppler visibility of UWB random noise radar depends primarily on the following parameters: (a) the local oscillator (LO) drive level of the receiver heterodyne mixer; (b) the saturation current in the receiver heterodyne mixer; (c) the bandwidth of the transmit noise source, and; (d) the target velocity. Other parameters such as the carrier frequency of the receiver LO and the loaded quality factor of the LO have a small effect over the range of applicability of the model and are therefore neglected in the model formulation. The Doppler visibility curves generated from this formula match the simulation results very well over the applicable parameter range within 1 dB. Our model may therefore be used to quickly estimate the Doppler visibility of random noise radars for trade-off analysis.
Stochastic resonance enhanced by dichotomic noise in a bistable system
Rozenfeld, Robert [Institute for Physics, Humboldt University at Berlin, D-10115, Berlin, (Germany); Neiman, Alexander [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Schimansky-Geier, Lutz [Institute for Physics, Humboldt University at Berlin, D-10115, Berlin, (Germany)
2000-09-01
We study linear responses of a stochastic bistable system driven by dichotomic noise to a weak periodic signal. We show that the effect of stochastic resonance can be greatly enhanced in comparison with the conventional case when dichotomic forcing is absent, that is, both the signal-to-noise ratio and the spectral power amplification reach much greater values than in the standard stochastic resonance setup. (c) 2000 The American Physical Society.
PHASE NOISE COMPARISON OF SHORT PULSE LASER SYSTEMS
Shukui Zhang; Stephen Benson; John Hansknecht; David Hardy; George Neil; Michelle D. Shinn
2006-08-27
This paper describes phase noise measurements of several different laser systems that have completely different gain media and configurations including a multi-kW free-electron laser. We will focus on state-of-the-art short pulse lasers, especially drive lasers for photocathode injectors. Phase noise comparison of the FEL drive laser, electron beam and FEL laser output also will be presented.
Phase Noise Comparision of Short Pulse Laser Systems
S. Zhang; S. V. Benson; J. Hansknecht; D. Hardy; G. Neil; Michelle D. Shinn
2006-12-01
This paper describes the phase noise measurement on several different mode-locked laser systems that have completely different gain media and configurations including a multi-kW free-electron laser. We will focus on the state of the art short pulse lasers, especially the drive lasers for photocathode injectors. A comparison between the phase noise of the drive laser pulses, electron bunches and FEL pulses will also be presented.
O. Baran
2010-12-01
Full Text Available Our work deals with studies of a noise behavior in space communication systems. Two most important noise types the additive thermal noise and the multiplicative phase noise, respectively, are included. A simple model of the narrowband communication system is created and simulated in the Ansoft Designer system simulator. The additive thermal noise is modeled as AWGN in a communication channel. The phase noise is produced in transmitter and receiver oscillators. The main intention is to investigate the receiver filter bandwidth decrease effect on powers of both noise types. Results proposed in this paper show that for defined system conditions and for a certain filter bandwidth value, the power of the multiplicative phase noise equals to the additive thermal noise power. Another decrease of the filter bandwidth causes the phase noise power exceeding. To demonstrate the noise behavior transparently, input system parameters are properly selected. All simulation results are documented by theoretical calculations. Simulation outcomes express a good coincidence with presumptions and calculations.
Hot-electron noise properties of graphene-like systems
Rustagi, A.; Stanton, C. J.
2014-12-01
We study the hot-electron noise properties of two-dimensional materials with a graphene-like energy dispersion under a strong applied electric field which drives the system far from equilibrium. Calculations are based on a Boltzmann-Green-function method within a two-relaxation-time approximation that allows for both inelastic scattering coming from electron-phonon scattering and elastic scattering coming from electron-impurity scattering. The steady-state distribution function is used to calculate the average current and the low-frequency spectral density for current fluctuations (noise) in the nonequilibrium steady-state. We find that as the electric field strength increases, the noise decreases from its equilibrium thermal noise value. This is in contrast with semiconductors with a quadratic energy-wave-vector dispersion where the noise increases in a constant-relaxation-time model with the square of the electric field due to the Joule heating of the electron gas by the electric field. We have also studied these properties for an electronic dispersion with a gap introduced into the Dirac spectrum. The inclusion of the gap in the electronic dispersion causes an initial increase in the noise as a function of external electric field due to the heating of the electron gas for large gap values. At high electric fields, the noise decreases with increasing electric field as in the case of gapless dispersion at higher fields.
Lee, R. A.; Rau, T. H.; Jones, C.
1982-07-01
The hush-house noise suppressor was made by Aero Systems Engineering of Texas, Inc. for acoustical suppression of various AF fighter/trainer aircraft during ground runup operations. This report provides measured and extrapolated data defining the bioacoustic environments produced by several aircraft/engines operating in the hush-house suppressor for various engine power configurations. Far-field data measured at 20 locations are normalized to standard meteorological conditions and extrapolated from 75-8000 meters to derive sets of equal-value contours for seven acoustic measures as function of angle and distance from the source. Refer to Volume 1 of this handbook, 'USAF Bioenvironmental Noise Data Handbook, Vol 1: Organization, Content and Application,' AMRL-TR-75(1) 1975, for discussion of the objective and design of the handbook, the types of data presented, measurement procedures, instrumentation, data processing, definitions of quantities, symbols, equations, applications, limitations, etc. Data are presented for the following aircraft/engines operating in the hush-house noise suppressor: F-4, F-15, F-16, F-105, F-106, F-111F and T-38 aircraft and the TF41-A-1, J79-GE-15, F100-PW-100, J75-P19, J-75-P-17 and TF30-P-100 engines.
Battery and electrochemical systems program summary, FY 1977
Webster, W. H. [ed.
1978-04-01
The success of wind and photovoltaic energy conversion systems for residential, commercial, and industrial applications is highly dependent on the development of a cost-effective battery storage system to provide power during periods of no wind or sunlight. The use of 3 to 9 million electric cars by the year 2000 will result in an oil saving from 35 to 90 million barrels per year. During FY 1977, STOR committed $13.3 million of its funds to these electrochemical programs, and managed an additional $5.6 million for the Division of Transportation Energy Conservation to develop near-term batteries for electric vehicles. This publication consists of summaries of all these programs, including contractors, major subcontracts, names of program managers, funding, and a brief description of the objectives and status of each program.
Vilar, J. M. G.; Rubí Capaceti, José Miguel
2001-01-01
We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.
Jones, Ryan J R; Shinde, Aniketa; Guevarra, Dan; Xiang, Chengxiang; Haber, Joel A; Jin, Jian; Gregoire, John M
2015-02-09
Many energy technologies require electrochemical stability or preactivation of functional materials. Due to the long experiment duration required for either electrochemical preactivation or evaluation of operational stability, parallel screening is required to enable high throughput experimentation. Imposing operational electrochemical conditions to a library of materials in parallel creates several opportunities for experimental artifacts. We discuss the electrochemical engineering principles and operational parameters that mitigate artifacts in the parallel electrochemical treatment system. We also demonstrate the effects of resistive losses within the planar working electrode through a combination of finite element modeling and illustrative experiments. Operation of the parallel-plate, membrane-separated electrochemical treatment system is demonstrated by exposing a composition library of mixed-metal oxides to oxygen evolution conditions in 1 M sulfuric acid for 2 h. This application is particularly important because the electrolysis and photoelectrolysis of water are promising future energy technologies inhibited by the lack of highly active, acid-stable catalysts containing only earth abundant elements.
Characterization of electrochemical systems and batteries: Materials and systems
McBreen, J.
1992-01-01
Materials are a pacing problem in battery development. The battery environment, particularly in rechargeable batteries, places great demands on materials. Characterization of battery materials is difficult because of their complex nature. In many cases meaningful characterization requires iii situ methods. Fortunately, several new electrochemical and spectroscopic techniques for in situ characterization studies have recently become available, and reports of new techniques have become more frequent. The opportunity now exists to utilize advanced instrumentation to define detailed features, participating chemical species and interfacial structure of battery materials with a precision heretofore not possible. This overview gives key references to these techniques and discusses the application of x-ray absorption spectroscopy to the study of battery materials.
Characterization of electrochemical systems and batteries: Materials and systems
McBreen, J.
1992-12-01
Materials are a pacing problem in battery development. The battery environment, particularly in rechargeable batteries, places great demands on materials. Characterization of battery materials is difficult because of their complex nature. In many cases meaningful characterization requires iii situ methods. Fortunately, several new electrochemical and spectroscopic techniques for in situ characterization studies have recently become available, and reports of new techniques have become more frequent. The opportunity now exists to utilize advanced instrumentation to define detailed features, participating chemical species and interfacial structure of battery materials with a precision heretofore not possible. This overview gives key references to these techniques and discusses the application of x-ray absorption spectroscopy to the study of battery materials.
Coupled dynamic systems and Le Chatelier's principle in noise control
Maidanik, G.; Becker, K. J.
2004-05-01
Investigation of coupling an externally driven dynamic system-a master dynamic system-to a passive one-an adjunct dynamic system-reveals that the response of the adjunct dynamic system affects the precoupled response of the master dynamic system. The responses, in the two dynamic systems when coupled, are estimated by the stored energies (Es) and (E0), respectively. Since the adjunct dynamic system, prior to coupling, was with zero (0) stored energy, E0s=0, the precoupled stored energy (E00) in the master dynamic system is expected to be reduced to (E0) when coupling is instituted; i.e., one expects E0
Duality between noise and spatial resolution in linear systems.
Gureyev, Timur E; Nesterets, Yakov I; de Hoog, Frank; Schmalz, Gerd; Mayo, Sheridan C; Mohammadi, Sara; Tromba, Giuliana
2014-04-21
It is shown that in a broad class of linear systems, including general linear shift-invariant systems, the spatial resolution and the noise satisfy a duality relationship, resembling the uncertainty principle in quantum mechanics. The product of the spatial resolution and the standard deviation of output noise in such systems represents a type of phase-space volume that is invariant with respect to linear scaling of the point-spread function, and it cannot be made smaller than a certain positive absolute lower limit. A corresponding intrinsic "quality" characteristic is introduced and then evaluated for the cases of some popular imaging systems, including computed tomography, generic image convolution and phase-contrast imaging. It is shown that in the latter case the spatial resolution and the noise can sometimes be decoupled, potentially leading to a substantial increase in the imaging quality.
Interference suppression in noise radar systems
Djukanović, Slobodan; Daković, Miloš; Thayaparan, Thayananthan; Stanković, Ljubiša
2011-06-01
This paper addresses the issue of interference suppression in noise radars. The proposed methods can be divided into non-parametric and parametric ones. The considered non-parametric methods are based on linear time-frequency (TF) tools, namely the short-time Fourier transform (STFT) and local polynomial Fourier transform (LPFT). The STFT is the simplest TF method, but, due to the resolution problem, it performs poorly with highly nonstationary interferences. The LPFT resolves the resolution problem, however at the cost of increased complexity. In parametric methods, the phase of interference is locally approximated by a polynomial, which is motivated by the Weierstrass's theorem. Using the phase approximation, the corrupted received signal is demodulated and successively filtered. Two methods for polynomial phase approximation are considered, the high-order ambiguity function (HAF) and product high-order ambiguity function (PHAF). The method based on the HAF is computationally efficient; however, it suffers from the identifiability problem when multicomponent signals are considered. The identifiability problem can be resolved using the PHAF.
Real-Time Telemetry System for Amperometric and Potentiometric Electrochemical Sensors
Ching-Hsing Luo
2011-09-01
Full Text Available A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC, a microcontroller unit (MCU, a graphical user interface (GUI, and a radio frequency (RF transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA. The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R2 value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R2 value greater than 0.99 was obtained in each experiment, a small size of 5.6 cm × 8.7 cm, high portability, and high integration.
Model independent control of lightly damped noise/vibration systems.
Yuan, Jing
2008-07-01
Feedforward control is a popular strategy of active noise/vibration control. In well-damped noise/vibration systems, path transfer functions from actuators to sensors can be modeled by finite impulse response (FIR) filters with negligible errors. It is possible to implement noninvasive model independent feedforward control by a recently proposed method called orthogonal adaptation. In lightly damped noise/vibration systems, however, path transfer functions have infinite impulse responses (IIRs) that cause difficulties in design and implementation of broadband feedforward controllers. A major source of difficulties is model error if IIR path transfer functions are approximated by FIR filters. In general, active control performance deteriorates as model error increases. In this study, a new method is proposed to design and implement model independent feedforward controllers for broadband in lightly damped noise/vibration systems. It is shown analytically that the proposed method is able to drive the convergence of a noninvasive model independent feedforward controller to improve broadband control in lightly damped noise/vibration systems. The controller is optimized in the minimum H2 norm sense. Experiment results are presented to verify the analytical results.
Wittchen, Andreas; the LPF Collaboration
2017-05-01
LISA Pathfinder is a technology demonstration mission for the space-based gravitational wave observatory, LISA. It demonstrated that the performance requirements for the interferometric measurement of two test masses in free fall can be met. An important part of the data analysis is to identify the limiting noise sources. [1] This measurement is performed with heterodyne interferometry. The performance of this optical metrology system (OMS) at high frequencies is limited by sensing noise. One such noise source is Relative Intensity Noise (RIN). RIN is a property of the laser, and the photodiode current generated by the interferometer signal contains frequency dependant RIN. From this electric signal the phasemeter calculates the phase change and laser power, and the coupling of RIN into the measurement signal depends on the noise frequency. RIN at DC, at the heterodyne frequency and at two times the heterodyne frequency couples into the phase. Another important noise at high frequencies is path length noise. To reduce the impact this noise is suppressed with a control loop. Path length noise not suppressed will couple directly into the length measurement. The subtraction techniques of both noise sources depend on the phase difference between the reference signal and the measurement signal, and thus on the test mass position. During normal operations we position the test mass at the interferometric zero, which is optimal for noise subtraction purposes. This paper will show results from an in-flight experiment where the test mass position was changed to make the position dependant noise visible.
Integrated Computational System for Electrochemical Device Design and Simulation Project
National Aeronautics and Space Administration — Illinois Rocstar LLC proposes to develop and demonstrate the use of an integrated computational environment and infrastructure for electrochemical device design and...
Amplifiers Module Prototype for the Johnson Noise Thermometry System
Britton Jr, Charles L [ORNL; Bull, Nora D [ORNL; Roberts, Michael [ORNL
2013-06-01
This document is intended to summarize the development and testing of the amplifier module portion of the Johnson Noise Thermometry (JNT) system developed at ORNL. The proposed system has been presented in an earlier report [1]. A more extensive project background including the project rationale is available in the initial project report [2].
The minimization of ac phase noise in interferometric systems
Filinski, Ignacy; Gordon, R A
1994-01-01
A simple step-by-step procedure, including several novel techniques discussed in the Appendices, is given for minimizing ac phase noise in typical interferometric systems such as two-beam interferometers, holographic setups, four-wave mixers, etc. Special attention is given to index of refraction...... fluctuations, direct mechanical coupling, and acoustic coupling, whose importance in determining ac phase noise in interferometric systems has not been adequately treated. The minimization procedure must be carried out while continuously monitoring the phase noise which can be done very simply by using...... with the optical table will also have to be carefully carried out regardless of the type of interferometric system employed.It is recommended that this be followed by a simple, inexpensive change to a novel type of interferometer discussed in Appendix A which is inherently less sensitive to mechanical vibration...
Low bitrate system design in the presence of phase noise
Haugli, Hans-Christian
1995-01-01
There are a number of interesting mobile satellite applications that require the transmission of short packets of data. In the design of such systems one of the challenges is often to minimize the transmitted power to reduce cost, which implies using power efficient low bit-rate modulation and coding methods. PSK systems can be very power efficient, but at low bit-rates the carrier recovery circuits can be sensitive to oscillator phase noise. In this paper we address the problem of determining the lowest bit-rate that can be supported using PSK for a given level of system phase noise. The classical formulas are reviewed, and a method is derived to calculate the minimum C/N(sub 0) required to recover the carrier for CW, BPSK and QPSK signals for a given phase noise level.
Electrochemical and mechanical polishing and shaping method and system
Engelhaupt, Darell E. (Inventor); Gubarev, Mikhail V. (Inventor); Jones, William David (Inventor); Ramsey, Brian D. (Inventor); Benson, Carl M. (Inventor)
2011-01-01
A method and system are provided for the shaping and polishing of the surface of a material selected from the group consisting of electrically semi-conductive materials and conductive materials. An electrically non-conductive polishing lap incorporates a conductive electrode such that, when the polishing lap is placed on the material's surface, the electrode is placed in spaced-apart juxtaposition with respect to the material's surface. A liquid electrolyte is disposed between the material's surface and the electrode. The electrolyte has an electrochemical stability constant such that cathodic material deposition on the electrode is not supported when a current flows through the electrode, the electrolyte and the material. As the polishing lap and the material surface experience relative movement, current flows through the electrode based on (i) adherence to Faraday's Law, and (ii) a pre-processing profile of the surface and a desired post-processing profile of the surface.
Noise Pollution Control System in the Hospital Environment
Figueroa Gallo, LM; Olivera, JM
2016-04-01
Problems related to environmental noise are not a new subject, but they became a major issue to solve because of the increasing, in complexity and intensity, of human activities due technological advances. Numerous international studies had dealt with the exposure of critical patients to noisy environment such as the Neonatal Intensive Care Units; their results show that there are difficulties in the organization in the developing brain, it can damage the delicate auditory structures and can cause biorhythm disorders, specially in preterm infants. The objective of this paper is to present the development and implementation of a control system that includes technical-management-training aspects to regulate the levels of specific noise sources in the neonatal hospitalization environment. For this purpose, there were applied different tools like: observations, surveys, procedures, an electronic control device and a training program for a Neonatal Service Unit. As a result, all noise sources were identified -some of them are eliminable-; all the service stable staff categories participated voluntarily; environmental noise measurements yielded values between 62.5 and 64.6 dBA and maximum were between 86.1 and 89.7 dBA; it was designed and installed a noise control device and the staff is being trained in noise reduction best practices.
Spectral Weighting Functions for Single-symbol Phase-noise Specifications in OFDM Systems
Hoeksema, Fokke; Schiphorst, Roel; Slump, Kees
2003-01-01
For the specification of phase-noise requirements for the front-end of a HiperLAN/2 system we investigated available literature on the subject. Literature differed in several aspects. One aspect is in the type of phase-noise used (Wiener phase-noise or small-angle phase noise). A Wiener phase-noise
A Novel Electromotance Noise Mitigation System Project
National Aeronautics and Space Administration — Electromotance energy has historically produced problems for electrical systems. This project will innovatively employ high electron density fields that have the...
Mirjana Rajčić Vujasinović
2009-09-01
Full Text Available Electrochemical systems with high capacities demand devices for electrochemical impedance spectroscopy (EIS with ultra-low frequencies (in order of mHz, that are almost impossible to accomplish with analogue techniques, but this becomes possible by using a computer technique and accompanying digital equipment. Recently, an original software and hardware for electrochemical measurements, intended for electrochemical systems exhibiting high capacities, such as supercapacitors, has been developed. One of the included methods is EIS. In this paper, the method of calculation of circuit parameters from an EIS curve is described. The results of testing on a physical model of an electrochemical system, constructed of known elements (including a 1.6 F capacitor in a defined arrangement, proved the validity of the system and the method.
Gering, Kevin L.
2013-01-01
A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics. The computing system also analyzes the cell information of the electrochemical cell with a Butler-Volmer (BV) expression modified to determine exchange current density of the electrochemical cell by including kinetic performance information related to pulse-time dependence, electrode surface availability, or a combination thereof. A set of sigmoid-based expressions may be included with the modified-BV expression to determine kinetic performance as a function of pulse time. The determined exchange current density may be used with the modified-BV expression, with or without the sigmoid expressions, to analyze other characteristics of the electrochemical cell. Model parameters can be defined in terms of cell aging, making the overall kinetics model amenable to predictive estimates of cell kinetic performance along the aging timeline.
Stević, Zoran; Vujasinović, Mirjana Rajčić; Radunović, Milan
2009-01-01
Electrochemical systems with high capacities demand devices for electrochemical impedance spectroscopy (EIS) with ultra-low frequencies (in order of mHz), that are almost impossible to accomplish with analogue techniques, but this becomes possible by using a computer technique and accompanying digital equipment. Recently, an original software and hardware for electrochemical measurements, intended for electrochemical systems exhibiting high capacities, such as supercapacitors, has been developed. One of the included methods is EIS. In this paper, the method of calculation of circuit parameters from an EIS curve is described. The results of testing on a physical model of an electrochemical system, constructed of known elements (including a 1.6 F capacitor) in a defined arrangement, proved the validity of the system and the method.
Stević, Zoran; Vujasinović, Mirjana Rajčić; Radunović, Milan
2009-01-01
Electrochemical systems with high capacities demand devices for electrochemical impedance spectroscopy (EIS) with ultra-low frequencies (in order of mHz), that are almost impossible to accomplish with analogue techniques, but this becomes possible by using a computer technique and accompanying digital equipment. Recently, an original software and hardware for electrochemical measurements, intended for electrochemical systems exhibiting high capacities, such as supercapacitors, has been developed. One of the included methods is EIS. In this paper, the method of calculation of circuit parameters from an EIS curve is described. The results of testing on a physical model of an electrochemical system, constructed of known elements (including a 1.6 F capacitor) in a defined arrangement, proved the validity of the system and the method. PMID:22400000
Positive Effect of Noises on Sensory Systems
Jun Liu; Guang Li
2004-01-01
Stochastic resonance phenomenon in the biological sensory systems has been studied through the signal detection theories and the psychophysical experiments. In this paper, sensory systems are considered as a threshold detector including the receiver part and the classifier part. Compared with conventional models regarding the receiver part of sensory system as a linear or single non-linear system, a summing network was constructed by MacCulloch-Pitts neurons to simulate the receiver part. The simulation results show that the relevant index of the detectability of signal exhibit the stochastic resonance behaviours. The psychophysical experiments were carried out through the 2IFC (two interval two alternative forced choice) method. The experimental results qualitatively verify the conclusion in accordance with the theoretical model.These works give a proof that stochastic resonance is not only epiphenonmenon in sensory systems.
Battlespace surveillance using netted wireless random noise radar systems
Surender, Shrawan C.; Narayanan, Ram M.
2005-05-01
Network-Centric Warfare (NCW) technology is currently being investigated to enhance the military"s effectiveness in the battlespace by providing the warfighter the necessary information to take proper decisions and win wars. One of the main battlespace requirements is surveillance, especially in today"s guerilla warfare theaters, such as the littoral and urban zones. NCW requires warfighters to be networked, self-organizing, spectrally undetectable, and having precise information about hostile targets in their vicinity. Towards this end, we are developing the concept of Netted Wireless Random Noise Radars, which is presented in this paper. The low probability-of-detection (LPD) and low probability-of-intercept (LPI) properties of random noise radars are well-known. Such radar sensors form a self-organizing network-centric architecture, using a deterministically fragmented spectrum to avoid spectral fratricide. The central concept is to use notch filtering to fragment parts of the band-limited non-coherent random noise waveform spectrum, and use these intermediate bandwidths for network communication (target tracking and track fusion) among the wireless sensors. For target detection and ranging, these sensors transmit random noise waveforms combined with continuous signals carrying digital data. As seen by the hostile target, the transmitted waveform appears random and noise-like. However, for the friendly sensors of this system, the noise-like signal contains camouflaged information. The advantages being envisioned with such a system are lower probability of detection due to noise-like transmissions, mobility to sensors due to the self-organizing capability, spectral efficiency due to fragmentation of spectrum, and better immunity to coherent interference due to the use of non-coherent signal waveforms.
Separation system with a sheath-flow supported electrochemical detector
Mathies, Richard A.; Emrich, Charles A.; Singhal, Pankaj; Ertl, Peter
2008-10-21
An electrochemical detector including side channels associated with a separation channel of a sample component separation apparatus is provided. The side channels of the detector, in one configuration, provide a sheath-flow for an analyte exiting the separation channel which directs the analyte to the electrically developed electrochemical detector.
DESI systems engineering: throughput and signal-to-noise
Besuner, Robert W.; Sholl, Michael J.
2016-08-01
The Dark Energy Spectroscopic Instrument (DESI) is a fiber-fed multi-object spectroscopic instrument under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. Management of light throughput and noise in all elements of the instrument is key to achieving the high-level DESI science requirements over the planned survey area and depth within the planned survey duration. The DESI high-level science requirements flow down to instrument performance requirements on system throughput and operational efficiency. Signal-to-noise requirements directly affect minimum required exposure time per field, which dictates the pace and duration of the entire survey. The need to maximize signal (light throughput) and to minimize noise contributions and time overhead due to reconfigurations between exposures drives the instrument subsystem requirements and technical implementation. Throughput losses, noise contributors, and interexposure reconfiguration time are budgeted, tracked, and managed as DESI Systems Engineering resources. Current best estimates of throughput losses and noise contributions from each individual element of the instrument are tracked together in a master budget to calculate overall margin on completing the survey within the allotted time. That budget is a spreadsheet accessible to the entire DESI project.
Impulse noise estimation and removal for OFDM systems
Al-Naffouri, Tareq Y.
2014-03-01
Orthogonal Frequency Division Multiplexing (OFDM) is a modulation scheme that is widely used in wired and wireless communication systems. While OFDM is ideally suited to deal with frequency selective channels and AWGN, its performance may be dramatically impacted by the presence of impulse noise. In fact, very strong noise impulses in the time domain might result in the erasure of whole OFDM blocks of symbols at the receiver. Impulse noise can be mitigated by considering it as a sparse signal in time, and using recently developed algorithms for sparse signal reconstruction. We propose an algorithm that utilizes the guard band subcarriers for the impulse noise estimation and cancellation. Instead of relying on ℓ1 minimization as done in some popular general-purpose compressive sensing schemes, the proposed method jointly exploits the specific structure of this problem and the available a priori information for sparse signal recovery. The computational complexity of the proposed algorithm is very competitive with respect to sparse signal reconstruction schemes based on ℓ1 minimization. The proposed method is compared with respect to other state-of-the-art methods in terms of achievable rates for an OFDM system with impulse noise and AWGN. © 2014 IEEE.
System Noise Prediction of the DGEN 380 Turbofan Engine
Berton, Jeffrey J.
2015-01-01
The DGEN 380 is a small, separate-flow, geared turbofan. Its manufacturer, Price Induction, is promoting it for a small twinjet application in the emerging personal light jet market. Smaller, and producing less thrust than other entries in the industry, Price Induction is seeking to apply the engine to a 4- to 5-place twinjet designed to compete in an area currently dominated by propeller-driven airplanes. NASA is considering purchasing a DGEN 380 turbofan to test new propulsion noise reduction technologies in a relevant engine environment. To explore this possibility, NASA and Price Induction have signed a Space Act Agreement and have agreed to cooperate on engine acoustic testing. Static acoustic measurements of the engine were made by NASA researchers during July, 2014 at the Glenn Research Center. In the event that a DGEN turbofan becomes a NASA noise technology research testbed, it is in the interest of NASA to develop procedures to evaluate engine system noise metrics. This report documents the procedures used to project the DGEN static noise measurements to flight conditions and the prediction of system noise of a notional airplane powered by twin DGEN engines.
Musa, Arnaud Emmanuel
for further electrochemical investigations in this thesis. Based on these electrochemical systems, the fabrication of potentiometric pH-sensors featuring a photo-curable polyurethane membrane as ion-selective-membrane (ISM) was then studied. The choice of the membrane was motivated by the fact...
Savel' ev, S., E-mail: S.Saveliev@lboro.ac.uk [Department of Physics, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Advanced Science Institute, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Zagoskin, A.M. [Department of Physics, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Advanced Science Institute, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Omelyanchouk, A.N. [Advanced Science Institute, RIKEN, Wako-shi, Saitama 351-0198 (Japan); B. Verkin Institute for Low Temperature Physics and Engineering, 61103 Kharkov (Ukraine); Nori, Franco [Advanced Science Institute, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Physics Department, University of Michigan, Ann Arbor, MI 48109-1040 (United States)
2010-10-05
Imagine that you have several sets of two coupled qubits, but you do not know the parameters of their Hamitonians. How to determine these without resorting to the usual spectroscopy approach to the problem? Based on numerical modeling, we show that all the parameters of a system of two coupled qubits can be determined by applying to it an external classical noise and analyzing the Fourier spectrum of the elements of the system's density matrix. In particular, the interlevel spacings as well as the strength and sign of the qubit-qubit coupling can be determined this way.
Highly selective NOx reduction for diesel engine exhaust via an electrochemical system
Shao, Jing; Tao, Youkun; Kammer Hansen, Kent
2016-01-01
It is challenging to reduce the nitrogen oxides (NOx) in diesel engine exhaust due to the inhibiting effect of excess oxygen. In this study, a novel electrochemical deNOx system was developed, which eliminated the need for additional reducing materials or a sophisticated controlling system as used...... in current diesel after-treatment techniques. The electrochemical system consisted of an electrochemical cell modified with NOx adsorbents and a diesel oxidation catalyst placed upstream of the cell. The system offers highly selective NOx reduction and a strong resistance to oxygen interference with almost...
Noise-induced multimode behavior in excitable systems
Postnov, D E; Sosnovtseva, Olga; Han, S K;
2002-01-01
Based on experiments with electronic circuits, we show how a system of coupled excitable units can possess several noise-induced oscillatory modes. We characterize the multimode organization in terms of the coherence resonance effect. Multiple gain of regularity is found to be related to different...
Modelling of Substrate Noise and Mitigation Schemes for UWB Systems
Shen, Ming; Mikkelsen, Jan H.; Larsen, Torben
2012-01-01
The last chapter of this first part of the book, chapter seven, is devoted to Modeling of Substrate Noise and Mitigation Schemes for Ultrawideband (UWB) systems, and is written by Ming Shen, Jan H. Mikkelsen, and Torben Larsen from Aalborg University, Denmark. In highly integrated mixed-mode desi...
Anti noise system and method using broadband radiation modes
Berkhoff, Arthur Perry
2005-01-01
Anti noise system and method, in particular for suppressing sound radiated from a structure, using a formulation of the most efficiently radiating vibration patterns of a vibrating body, the radiation modes, in the time domain. The radiation modes can be used to arrive at efficient weighting schemes
Applying intelligent transport systems to manage noise impacts
Wilmink, I.R.; Vonk, T.
2015-01-01
This contribution discusses how traffic management, and many other measures that can be categorised as Intelligent Transport Systems (ITS, i.e. all traffic and transport measures that use ICT) can help reduce noise levels by influencing mobility choices and driving behaviour. Several examples of suc
Wang Can-Jun; Chen Shi-Bo; Mei Dong-Cheng
2006-01-01
The steady-state properties of a bistable system are investigated when both the multiplicative noise and the coupling between additive and multiplicative noises are coloured with different values of noise correlation times τ1 and 72. After introducing a dimensionless parameter R(R = α/D, D is the intensity of the multiplicative noise and α is the intensity of the additive noise), and performing the numerical computations, we find the following points: (1) For the case ofR ＞ 1, λ (the intensity of correlation between additive and multiplicative noises), τ1 and τ2 can induce the stationary probability distribution (SPD) transition from bimodal to unimodal in structure, but for the cases of R ≤ 1,the bimodal structure is preserved; (2) α can also induce the SPD transition from bimodal to unimodal in structure;(3) the bimodal structure of the SPD exhibits a symmetrical structure as D increases.
The NASA aircraft noise prediction program improved propeller analysis system
Nguyen, L. Cathy
1991-01-01
The improvements and the modifications of the NASA Aircraft Noise Prediction Program (ANOPP) and the Propeller Analysis System (PAS) are described. Comparisons of the predictions and the test data are included in the case studies for the flat plate model in the Boundary Layer Module, for the effects of applying compressibility corrections to the lift and pressure coefficients, for the use of different weight factors in the Propeller Performance Module, for the use of the improved retarded time equation solution, and for the effect of the number grids in the Transonic Propeller Noise Module. The DNW tunnel test data of a propeller at different angles of attack and the Dowty Rotol data are compared with ANOPP predictions. The effect of the number of grids on the Transonic Propeller Noise Module predictions and the comparison of ANOPP TPN and DFP-ATP codes are studied. In addition to the above impact studies, the transonic propeller noise predictions for the SR-7, the UDF front rotor, and the support of the enroute noise test program are included.
Design of a dual-mode electrochemical measurement and analysis system.
Yang, Jr-Fu; Wei, Chia-Ling; Wu, Jian-Fu; Liu, Bin-Da
2013-01-01
A dual-mode electrochemical measurement and analysis system is proposed. This system includes a dual-mode chip, which was designed and fabricated by using TSMC 0.35 µm 3.3 V/5 V 2P4M mixed-signal CMOS process. Two electrochemical measurement and analysis methods, chronopotentiometry and voltammetry, can be performed by using the proposed chip and system. The proposed chip and system are verified successfully by performing voltammetry and chronopotentiometry on solutions.
Method and System for Active Noise Control of Tiltrotor Aircraft
Betzina, Mark D. (Inventor); Nguyen, Khanh Q. (Inventor)
2003-01-01
Methods and systems for reducing noise generated by rotating blades of a tiltrotor aircraft. A rotor-blade pitch angle associated with the tiltrotor aircraft can be controlled utilizing a swashplate connected to rotating blades of the tiltrotor aircraft. One or more Higher Harmonic Control (HHC) signals can be transmitted and input to a swashplate control actuator associated with the swashplate. A particular blade pitch oscillation (e.g., four cycles per revolution) is there-after produced in a rotating frame of reference associated with the rotating blades in response to input of an HHC signal to the swashplate control actuator associated with the swashplate to thereby reduce noise associated with the rotating blades of the tiltrotor aircraft. The HHC signal can be transmitted and input to the swashplate control actuator to reduce noise of the tiltrotor aircraft in response to a user input utilizing an open-loop configuration.
Electrochemical Double Layered Capacitor Development and Implementation System
Strunk, Gavin P.
Electrochemical Double Layered Capacitors (EDLC's) are becoming a more popular topic of research for hybrid power systems, especially vehicles. They are known for their high power density, high cycle life, low internal resistance, and wider operating temperature compared to batteries. They are rarely used as a standalone power source; however, because of their lack of energy density compared to batteries and fuel cells. Researchers are now discovering the benefits of using them in hybrid systems. The increased complexity of a hybrid power source presents many challenges. A major drawback of this complexity is the lack of design tools to assist a designer in translating a simulation all the way to a full scale implementation. A full spectrum of tools was designed to assist designers at all stages of implementation including: single cell testing, a multi-cell management system, and a full scale vehicle data acquisition system to monitor performance. First, the full scale vehicle data acquisition is described. The system is isolated from the electric shuttle bus it was tested on to allow the system to be ported to other vehicles and applications. This was done to modularize the system to characterize a wide variety of full scale applications. Next, a single cell test system was designed that allows the designer to characterize cell specifications, as well as, test control and safety systems in a controlled environment. The goal is to ensure safety systems can be thoroughly tested to ensure robustness as the bank is scaled up. This system also includes simulation models that provide examples of using the simulation to predict the behavior of a cell and the test system to validate the results of the simulation. This information is then used by the designer to more effectively design sensor ranges for the bank. Finally, a multi-cell EDLC management system was designed to implement a bank. It incorporates 12 series EDLC cells per control module, and the modular design
Response of MDOF strongly nonlinear systems to fractional Gaussian noises
Deng, Mao-Lin; Zhu, Wei-Qiu
2016-08-01
In the present paper, multi-degree-of-freedom strongly nonlinear systems are modeled as quasi-Hamiltonian systems and the stochastic averaging method for quasi-Hamiltonian systems (including quasi-non-integrable, completely integrable and non-resonant, completely integrable and resonant, partially integrable and non-resonant, and partially integrable and resonant Hamiltonian systems) driven by fractional Gaussian noise is introduced. The averaged fractional stochastic differential equations (SDEs) are derived. The simulation results for some examples show that the averaged SDEs can be used to predict the response of the original systems and the simulation time for the averaged SDEs is less than that for the original systems.
Response of MDOF strongly nonlinear systems to fractional Gaussian noises
Deng, Mao-Lin; Zhu, Wei-Qiu, E-mail: wqzhu@zju.edu.cn [Department of Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Zhejiang University, Hangzhou 310027 (China)
2016-08-15
In the present paper, multi-degree-of-freedom strongly nonlinear systems are modeled as quasi-Hamiltonian systems and the stochastic averaging method for quasi-Hamiltonian systems (including quasi-non-integrable, completely integrable and non-resonant, completely integrable and resonant, partially integrable and non-resonant, and partially integrable and resonant Hamiltonian systems) driven by fractional Gaussian noise is introduced. The averaged fractional stochastic differential equations (SDEs) are derived. The simulation results for some examples show that the averaged SDEs can be used to predict the response of the original systems and the simulation time for the averaged SDEs is less than that for the original systems.
Response of MDOF strongly nonlinear systems to fractional Gaussian noises.
Deng, Mao-Lin; Zhu, Wei-Qiu
2016-08-01
In the present paper, multi-degree-of-freedom strongly nonlinear systems are modeled as quasi-Hamiltonian systems and the stochastic averaging method for quasi-Hamiltonian systems (including quasi-non-integrable, completely integrable and non-resonant, completely integrable and resonant, partially integrable and non-resonant, and partially integrable and resonant Hamiltonian systems) driven by fractional Gaussian noise is introduced. The averaged fractional stochastic differential equations (SDEs) are derived. The simulation results for some examples show that the averaged SDEs can be used to predict the response of the original systems and the simulation time for the averaged SDEs is less than that for the original systems.
On UWB system performance under impulsive noise environment
贾琳; 张中兆
2004-01-01
In this paper, the performance of UWB (ultrawide bandwidth) radio systems under impulsive noise environment (INE) is investigated. At first, the Middleton's class a model is used as a model of impulsive noise (IN), we investigate the statistical characteristics of in-phase and quadrature components of IN, and it is proved that unlike Gaussian noise (GN), they are dependent especially to IN with small impulsive indices, Then, making use of this dependence between in-phase and quadrature components, an ovel UWB radio receiver designed for IN is proposed. The exact expression for the average BER (bit error rate) of this receiver, which is a function of SNR (signal to noise power ratio) and threshold value, is derived. Thirdly, we'll discuss the optimum threshold value. We'll also estimate the performance of UWB radio systems with the proposed receiver designed for IN and with the conventional receiver designed for GN in INE. Numerical results show that the performance achieved by the proposed UWB radio receiver is much etter than that of the conventional UWB radio receiver. Meanwhile, it is shown that both impulsive index and threshold value have much effect on the performance of UWB radio system s under the condition of INE
Low noise multi-channel biopotential wireless data acquisition system for dry electrodes
Pandian, P. S.; Whitchurch, Ashwin K.; Abraham, Jose K.; Bhusan Baskey, Himanshu; Radhakrishnan, J. K.; Varadan, Vijay K.; Padaki, V. C.; Bhasker Rao, K. U.; Harbaugh, R. E.
2008-03-01
The bioelectrical potentials generated within the human body are the result of electrochemical activity in the excitable cells of the nervous, muscular or glandular tissues. The ionic potentials are measured using biopotential electrodes which convert ionic potentials to electronic potentials. The commonly monitored biopotential signals are Electrocardiogram (ECG), Electroencephalogram (EEG) and Electromyogram (EMG). The electrodes used to monitor biopotential signals are Ag-AgCl and gold, which require skin preparation by means of scrubbing to remove the dead cells and application of electrolytic gel to reduce the skin contact resistance. The gels used in biopotential recordings dry out when used for longer durations and add noise to the signals and also prolonged use of gels cause irritations and rashes to skin. Also noises such as motion artifact and baseline wander are added to the biopotential signals as the electrode floats over the electrolytic gel during monitoring. To overcome these drawbacks, dry electrodes are used, where the electrodes are held against the skin surface to establish contact with the skin without the need for electrolytic fluids or gels. The major drawback associated with the dry electrodes is the high skin-electrode impedance in the low frequency range between 0.1-120 Hz, which makes it difficult to acquire clean and noise free biopotential signals. The paper presents the design and development of biopotential data acquisition and processing system to acquire biopotential signals from dry electrodes. The electrode-skin-electrode- impedance (ESEI) measurements was carried out for the dry electrodes by impedance spectroscopy. The biopotential signals are processed using an instrumentation amplifier with high CMRR and high input impedance achieved by boot strapping the input terminals. The signals are band limited by means of a second order Butterworth band pass filters to eliminate noise. The processed biopotential signals are digitized
Measurement of Supersonic Jet Noise with Optical Wave Microphone System
Masataka KOSAKA; Kunisato SETO; MD. Tawhidul Islam KHAN; Yoichi NAKAZONO
2005-01-01
An optical wave microphone system is a new technique of sound measurement. This technique has been developed as a new plasma diagnostic technique to measure electron density fluctuations in the nuclear fusion research. Because the sound wave is a pressure or a density fluctuation, it is possible for this technique to measure the sound wave, too. The acoustical characteristics of the optical wave microphone system were examined by using a speaker as a first step. Next, feasibility of this device to measure jet noise was examined. It was found that the optical wave microphone system could measure the jet noise as well as a sound from speaker.Hence the optical wave microphone system can be considered one of the devices equivalent to condenser microphone. Because of these reason, this device is very convenient to scan the acoustic filed through jet flow from the inside to the out side and more preferable for not disturbing the observation field.
System for electrochemical investigations based on a PC and the Lab VIEW package
Stević Zoran
2007-01-01
Full Text Available This paper describes an electrochemical research system based on the Lab VIEW computer software package. An overview of well known electrochemical methods, such as potential measurements, chronopotentiometry, chronoamperometry, cyclic voltammetry and EIS is given. Electrochemical impedance spectroscopy has been adapted for systems containing large capacitances. For signal generation and recording of the response of the investigated electrochemical cell, a measurement and control system was developed, based on a PC P4 computer. The rest of the hardware consists of a commercially available AD-DA converter and an external interface for analog signal processing. The interface is a result of the authors own research. The software platform for the desired measurement methods is Lab VIEW package, which is regarded as a high standard in the area of modern virtual instruments. The developed system was adjusted, tested and compared with other commercially available systems. One such system is in constant use at the Technical Faculty in Bor.
Bing Wang; Shaoping Yan
2009-01-01
Considering an optical bistable system with cross-correlated additive white noise and multiplicative colored noise,we study the effects of correlation between the noises on the correlation function C(s)using the unified colored noise approximation and the Stratonovich decoupling ansatz formalism.The effects of the self-correlation time T of the multiplicative colored noise and the correlation intensity A between the two noises are studied with numerical calculation.It is found that C(s)increases with the increase of the self-correlation time r,but decreases with the increase of the correlation intensity A.At large value of T,there is almost no change for C(s)when T changes.
Wu, Dong-Mei; Guo, Xiao-Ling; Wang, Qian; Li, Jin-Lian; Cui, Ji-Wen; Zhou, Shi; Hao, Su-E
2017-01-01
A novel mini-electrochemical system has been developed for evaluating cytotoxicity of anticancer drugs based on trace cell samples. The mini-electrochemical system was integrated by using pencil graphite modified with threonine as working electrode, an Ag/AgCl reference electrode and a micropipet tip as electrochemical cell. The mini-electrochemical system dramatically reduces sample volumes from 500 μL in a traditional electrochemical system to 10 μL, and exhibits excellent electrocatalytic activity toward oxidation of purine from MCF-7 cells due to increased sensitivity provided by threonine. Moreover, the relationship between peak current and the cell concentration in the range from 3.0 × l0(3) to 7.0 × l0(6) cells/mL was studied, and a nonlinear exponential relationship between them was established over a wide concentration range. In evaluating the effect of anticancer drugs on cell viability, the results of drug cytotoxicity test based on cyclophosphamide were in close agreement with classical 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assays. The proposed device is so simple, cheap, and easy to operate that it could be applied to single-use applications. The mini-electrochemical system proved to be a useful tool and can be applied to electrochemical studies of cancer cells as well as other biological samples such as proteins and DNA.
Noise simulation system for determining imaging conditions in digital radiography
Tanaka, R.; Ichikawa, K.; Matsubara, K.; Kawashima, H.
2012-03-01
Reduction of exposure dose and improvement in image quality can be expected to result from advances in the performance of imaging detectors. We propose a computerized method for determining optimized imaging conditions by use of simulated images. This study was performed to develop a prototype system for image noise and to ensure consistency between the resulting images and actual images. An RQA5 X-ray spectrum was used for determination of input-output characteristics of a flat-panel detector (FPD). The number of incident quantum to the detector per pixel (counts/pixel) was calculated according to the pixel size of the detector and the quantum number in RQA5 determined in IEC6220-1. The relationship among tube current-time product (mAs), exposure dose (C/kg) at the detector surface, the number of incident quanta (counts/pixel), and pixel values measured on the images was addressed, and a conversion function was then created. The images obtained by the FPD was converted into a map of incident quantum numbers and input into random-value generator to simulate image noise. In addition, graphic user interface was developed to observe images with changing image noise and exposure dose levels, which have trade-off relationship. Simulation images provided at different noise levels were compared with actual images obtained by the FPD system. The results indicated that image noise was simulated properly both in objective and subjective evaluation. The present system could allow us to determine necessary dose from image quality and also to estimate image quality from any exposure dose.
An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification
Conesa, Claudia; Ibáñez Civera, Javier; Seguí, Lucía; Fito, Pedro; Laguarda-Miró, Nicolás
2016-01-01
Electrochemical impedance spectroscopy (EIS) has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA) equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS) were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions) gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R2) and root mean square errors of prediction (RMSEP) were determined as R2 > 0.944 and RMSEP 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs), respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step. PMID:26861317
An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification
Claudia Conesa
2016-02-01
Full Text Available Electrochemical impedance spectroscopy (EIS has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R2 and root mean square errors of prediction (RMSEP were determined as R2 > 0.944 and RMSEP < 1.782 for PLS and R2 > 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs, respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step.
On the Criteria of Instability for Electrochemical Systems
LI,Ze-Lin(李则林); REN,Bin(任斌); NIU,Zhen-Jiang(牛振江); XIAO,Xiao-Ming(肖小明); ZENG,Yue(曾跃); TIAN,Zhong-Qun(田中群)
2002-01-01
Both cyclic-voltammetry-based and impedance-based experimental criteria that have been developed recently for the oscillatory electrochemical systems are critically appraised with two typical categories of oscillators. Consistent conchsions can be drawn by the two criteria for the category of oscillators that involve the coupling of charge transfer mainly with surface steps (e.g. ad- and desorption) such as in the electrooxidation of C1 organic molecules. Whereas, impedance- based criterion is not applicable to the category of oscillators that involve the coupling of charge transfer mainly with mass transfer ( e. g. diffusion and convection) such as in the Fe(CN)63- reduction accompanying periodic hydrogen evolulion. The reason is that the negative impedance cannot include the feedback information of convection mass transfer induced by the hydrogen evolution. How ever, both positive and negative nonlinear feedbacks, i.e.,the diffusion-limited depletion and convection-enhanced replenishment of the Fe(CN)63- surface concentration, that coexist between the bistability, i.e., Fe(CN)63- reduction with and without hydrogen evolution at lower and higher potential sides respectively, are all reflected in the crossed cyclic voltammogram (CCV). It con be concluded that the voltammety-based criterion (in time domain) is more intuitive, less time-consuming and has a wider range of applications than the impedancebased one (in frequency domain).
An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification.
Conesa, Claudia; Ibáñez Civera, Javier; Seguí, Lucía; Fito, Pedro; Laguarda-Miró, Nicolás
2016-02-04
Electrochemical impedance spectroscopy (EIS) has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA) equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS) were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions) gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R²) and root mean square errors of prediction (RMSEP) were determined as R² > 0.944 and RMSEP 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs), respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step.
Design and implementation of a noise radar tomographic system
Asmuth, Mark A.; Shin, Hee Jung; Narayanan, Ram M.; Rangaswamy, Muralidhar
2015-05-01
A hardware system has been developed to perform ultrawideband (UWB) noise radar tomography over the 3-5 GHz frequency range. The system utilizes RF hardware to transmit multiple independent and identically distributed UWB random noise waveforms. A 3-5 GHz band-limited signal is generated using an arbitrary waveform generator and the waveform is then amplified and transmitted through a horn antenna. A linear scanner with a single antenna is used in place of an antenna array to collect backscatter. The backscatter is collected from the transmission of each waveform and reconstructed to form an image. The images that result from each scan are averaged to produce a single tomographic image of the target. After background subtraction, the scans are averaged to improve the image quality. The experimental results are compared to the theoretical predictions. The system is able to successfully image metallic and dielectric cylinders of different cross sections.
Noise Separation from the Weak Signal Chaotic Detection System
Hanjie Gu
2014-11-01
Full Text Available The traditional weak signal chaotic detection system still restricts some technical issues in the situation of the signal with noise, such as poor denoising ability and low detection precision. In this paper, we propose a novel weak signal chaotic detection system based on an improved wavelet transform algorithm. First, the traditional wavelet transform algorithm domain variables have been transformed and discretized to eliminate the redundant transform. Then, based on the discrete optimization, the wavelet coefficients have been optimized by threshold compromise strategy. The improved wavelet transform algorithm is applied in the weak signal chaotic detection system. The noise signal after finite discrete processing is treated as a perturbation of cycle power and put into a chaotic system for detecting weak signal under the noise conditions. The simulation experiments show that the proposed improved wavelet transform algorithm has a better denoising effect than the traditional wavelet transform algorithm. Moreover, the improved algorithm shows better accuracy and higher robustness in the weak signal chaotic detection system.
Monolithic three-dimensional electrochemical energy storage system on aerogel or nanotube scaffold
Farmer, Joseph C; Stadermann, Michael
2013-11-12
A monolithic three-dimensional electrochemical energy storage system is provided on an aerogel or nanotube scaffold. An anode, separator, cathode, and cathodic current collector are deposited on the aerogel or nanotube scaffold.
Monolithic three-dimensional electrochemical energy storage system on aerogel or nanotube scaffold
Farmer, Joseph Collin; Stadermann, Michael
2014-07-15
A monolithic three-dimensional electrochemical energy storage system is provided on an aerogel or nanotube scaffold. An anode, separator, cathode, and cathodic current collector are deposited on the aerogel or nanotube scaffold.
Active Control of Fan Noise: Feasibility Study. Volume 4; Flyover System Noise Studies
Kraft, R. E.; Janardan, B. A.; Gliebe, P. R.; Kontos, G. C.
1996-01-01
An extension of a prior study has been completed to examine the potential reduction of aircraft flyover noise by the method of active noise control (ANC). It is assumed that the ANC system will be designed such that it cancels discrete tones radiating from the engine fan inlet or fan exhaust duct, at least to the extent that they no longer protrude above the surrounding broadband noise levels. Thus, without considering the engineering details of the ANC system design, tone levels am arbitrarily removed from the engine component noise spectrum and the flyover noise EPNL levels are compared with and without the presence of tones. The study was conducted for a range of engine cycles, corresponding to fan pressure ratios of 1.3, 1.45, 1.6, and 1.75. This report is an extension of an effort reported previously. The major conclusions drawn from the prior study, which was restricted to fan pressure ratios of 1.45 and 1.75, are that, for a fan pressure ratio of 1.75, ANC of tones gives about the same suppression as acoustic treatment without ANC. For a fan pressure ratio of 1.45, ANC appears to offer less effectiveness from passive treatment. In the present study, the other two fan pressure ratios are included in a more detailed examination of the benefits of the ANC suppression levels. The key results of this extended study are the following observations: (1) The maximum overall benefit obtained from suppression of BPF alone was 2.5 EPNdB at high fan speeds. The suppression benefit increases with increase in fan pressure ratio (FPR), (2) The maximum overall benefit obtained from suppression of the first three harmonics was 3 EPNdB at high speeds. Suppression benefit increases with increase in FPR, (3) At low FPR, only about 1.0 EPNdB maximum reduction was obtained. Suppression is primarily from reduction of BPF at high FPR values and from the combination of tones at low FPR, (4) The benefit from ANC is about the same as the benefit from passive treatment at fan pressure
Characterization and modeling of electrochemical energy conversion systems by impedance techniques
Klotz, Dino
2012-07-01
This work introduces (i) amendments to basic electrochemical measurement techniques in the time and frequency domain suitable for electrochemical energy conversion systems like fuel cells and batteries, which enable shorter measurement times and improved precision in both measurement and parameter identification, and (ii) a modeling approach that is able to simulate a technically relevant system just by information gained through static and impedance measurements of laboratory size cells.
Luo Xiao-Qin; Zhu Shi-Qun
2004-01-01
The phenomenon of stochastic resonance (SR) in a bistable nonlinear system with coupling between additive and multiplicative noises is investigated when the correlation between two noise terms is coloured. It is found that the signal-to-noise ratio (SNR) of the system is affected not only by the coupling strength λ between two noise terms, but also by the noise correlation time . The SNR is changed from a single peak, to two peaks with a dip, and then to a monotonically decreasing function with noise strength. The dependence of the SR on the initial conditions is entirely caused by the coupling strength λ between two noise terms.
Noise-induced temporal dynamics in Turing systems
Schumacher, Linus J.
2013-04-25
We examine the ability of intrinsic noise to produce complex temporal dynamics in Turing pattern formation systems, with particular emphasis on the Schnakenberg kinetics. Using power spectral methods, we characterize the behavior of the system using stochastic simulations at a wide range of points in parameter space and compare with analytical approximations. Specifically, we investigate whether polarity switching of stochastic patterns occurs at a defined frequency. We find that it can do so in individual realizations of a stochastic simulation, but that the frequency is not defined consistently across realizations in our samples of parameter space. Further, we examine the effect of noise on deterministically predicted traveling waves and find them increased in amplitude and decreased in speed. © 2013 American Physical Society.
Extreme value statistics for dynamical systems with noise
Faranda, Davide; Lucarini, Valerio; Turchetti, Giorgio; Vaienti, Sandro
2012-01-01
We study the distribution of maxima (Extreme Value Statistics) for sequences of observables computed along orbits generated by random transformations. The underlying, deterministic, dynamical system can be regular or chaotic. In the former case, we will show that by perturbing rational or irrational rotations with additive noise, an extreme value law will appear, regardless of the intensity of the noise, while unperturbed rotations do not admit such limiting distributions. In the case of deterministic chaotic dynamics, we will consider observables specially designed to study the recurrence properties in the neighbourhood of periodic points. The exponential limiting law for the distribution of maxima is therefore modified by the presence of the extremal index, a positive parameter not larger than one, whose inverse gives the average size of the clusters of extreme events. The theory predicts that such a parameter is unitary when the system is perturbed randomly. We perform sophisticated numerical tests to asse...
Noise robust linear dynamic system for phase unwrapping and smoothing.
Estrada, Julio C; Servin, Manuel; Quiroga, Juan A
2011-03-14
Phase unwrapping techniques remove the modulus ambiguities of wrapped phase maps. The present work shows a first-order feedback system for phase unwrapping and smoothing. This system is a fast sequential unwrapping system which also allows filtering some noise because in deed it is an Infinite Impulse Response (IIR) low-pass filter. In other words, our system is capable of low-pass filtering the wrapped phase as the unwrapping process proceeds. We demonstrate the temporal stability of this unwrapping feedback system, as well as its low-pass filtering capabilities. Our system even outperforms the most common and used unwrapping methods that we tested, such as the Flynn's method, the Goldstain's method, and the Ghiglia least-squares method (weighted or unweighted). The comparisons with these methods shows that our system filters-out some noise while preserving the dynamic range of the phase-data. Its application areas may cover: optical metrology, synthetic aperture radar systems, magnetic resonance, and those imaging systems where information is obtained as a demodulated wrapped phase map.
SPECTRON, a neutron noise measurement system in frequency domain.
de Izarra, G; Jammes, C; Geslot, B; Di Salvo, J; Destouches, C
2015-11-01
This paper is dedicated to the presentation and validation of SPECTRON, a novel neutron noise measurement system developed at CEA Cadarache. The device is designed for the measurement of the β(eff) parameter (effective fraction of delayed neutrons) of experimental nuclear reactors using the Cohn-α method. An integrated electronic system is used to record the current from fission chambers. Spectra computed from measurement data are processed by a dedicated software in order to estimate the reactor transfer function and then the effective fraction of delayed neutrons as well as the prompt neutron generation time. After a review of the pile noise measurement method in current mode, the SPECTRON architecture is presented. Then, the validation procedure is described and experimental results are shown, supporting the proper functioning of this new measurement system. It is shown that every technical requirement needed for correct measurement of neutron noise is fulfilled. Measurements performed at MINERVE and EOLE, two experimental nuclear reactors at CEA Cadarache, in real conditions allowed us to validate SPECTRON.
Acoustic FMRI noise: linear time-invariant system model.
Rizzo Sierra, Carlos V; Versluis, Maarten J; Hoogduin, Johannes M; Duifhuis, Hendrikus Diek
2008-09-01
Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For auditory system studies, however, the acoustic noise generated by the scanner tends to interfere with the assessments of this activation. Understanding and modeling fMRI acoustic noise is a useful step to its reduction. To study acoustic noise, the MR scanner is modeled as a linear electroacoustical system generating sound pressure signals proportional to the time derivative of the input gradient currents. The transfer function of one MR scanner is determined for two different input specifications: 1) by using the gradient waveform calculated by the scanner software and 2) by using a recording of the gradient current. Up to 4 kHz, the first method is shown as reliable as the second one, and its use is encouraged when direct measurements of gradient currents are not possible. Additionally, the linear order and average damping properties of the gradient coil system are determined by impulse response analysis. Since fMRI is often based on echo planar imaging (EPI) sequences, a useful validation of the transfer function prediction ability can be obtained by calculating the acoustic output for the EPI sequence. We found a predicted sound pressure level (SPL) for the EPI sequence of 104 dB SPL compared to a measured value of 102 dB SPL. As yet, the predicted EPI pressure waveform shows similarity as well as some differences with the directly measured EPI pressure waveform.
Phasor Representation for Narrowband Active Noise Control Systems
Chen Fu-Kun
2008-01-01
Full Text Available The phasor representation is introduced to identify the characteristic of the active noise control (ANC systems. The conventional representation, transfer function, cannot explain the fact that the performance will be degraded at some frequency for the narrowband ANC systems. This paper uses the relationship of signal phasors to illustrate geometrically the operation and the behavior of two-tap adaptive filters. In addition, the best signal basis is therefore suggested to achieve a better performance from the viewpoint of phasor synthesis. Simulation results show that the well-selected signal basis not only achieves a better convergence performance but also speeds up the convergence for narrowband ANC systems.
Photonic Delay-line Phase Noise Measurement System
2011-09-01
combined 500-m and 6-km delay-line measurement system. Noise floor data are shown for the system with and without an EDFA . The laser power was 10 dBm...The optical power into the photodiode was 0 dBm without the EDFA and 11 dBm with it...data are shown for the system with and without an EDFA as well as with a high-power laser. The output optical powers of the low and high-power
Phasor Representation for Narrowband Active Noise Control Systems
Fu-Kun Chen
2008-05-01
Full Text Available The phasor representation is introduced to identify the characteristic of the active noise control (ANC systems. The conventional representation, transfer function, cannot explain the fact that the performance will be degraded at some frequency for the narrowband ANC systems. This paper uses the relationship of signal phasors to illustrate geometrically the operation and the behavior of two-tap adaptive filters. In addition, the best signal basis is therefore suggested to achieve a better performance from the viewpoint of phasor synthesis. Simulation results show that the well-selected signal basis not only achieves a better convergence performance but also speeds up the convergence for narrowband ANC systems.
Polymer multilevel lab-on-chip systems for electrochemical sensing
Matteucci, Marco; Larsen, Simon Tylsgaard; Garau, Alessandro
2013-01-01
with depths as small as tens of nanometers and as big as hundreds of microns on the same polymer chip. The authors also describe in detail the fabrication procedure of polymer substrates with embedded Au and pedot:tosylate electrodes for electrochemical applications. The electrode fabrication process...... is simple and fit for integration in a production scheme. The electrode–substrates are then bonded to injection molded counterparts to be used for electrochemical applications. A dimensional and functional characterization of the electrodes is also presented here....
Stochastic Resonance in a Bistable System Subject to Dichotomous Noise
ZHOU Yu-Rong; PAN Hui-Mei; GUO Feng; PANG Xiao-Feng
2008-01-01
The stochastic resonance phenomenon in a bistable system subject to Markov dichotomous noise (DN) is investigated. Based on the adiabatic elimination and the two-state theories, the explicit expressions for the signal-to-noise ratio (SNR) and the spectral power amplification (SPA) have been obtained. It is shown that two peaks can occur on the curve of SNR versus the intensity of the DN. Moreover, the SNR is a non-monotonic function of the correlation time of the DN. The SPA varies non-monotonously with the strength of the DN. The dependence of the SNR on the frequency and the amplitude of the external periodic signal are discussed. The effect of the external frequency and the correlation time of the DN on the SPA are analyzed.
Electrochemical nano-coating processes in solar energy systems
F. Kadırgan
2006-01-01
Full Text Available The efficiencies of electrochemically prepared nano-thick CdS and black nickel coatings were investigated as a function of their preparation conditions in the application field of energy; such as, solar-electricity conversion, solar cells, and solar-thermal conversion, spectrally selective solar collectors.
Stochastic resonance in linear systems subject to multiplicative and additive noise.
Berdichevsky, V; Gitterman, M
1999-08-01
Exact expressions have been found for the first two moments and the correlation function for an overdamped linear system subject to an external periodic field as well as to multiplicative and additive noise. Stochastic resonance is absent for Gaussian white noise. However, when the multiplicative noise has the form of an asymmetric dichotomous noise, the signal-to-noise ratio (SNR) becomes a nonmonotonic function of the correlation time and the asymmetry of noise. Moreover, the SNR turns out to be a nonmonotonic function of the frequency of the external field as well as strongly depending on the strength of the cross correlation between multiplicative and additive noise.
An improved video median noise reduction algorithm for ambulance vehicle terminal monitoring system
Ma, Xian-Min; Zhang, Hang
2012-04-01
An improved video median noise reduction algorithm is presented for 120 vehicle terminal monitoring system in this paper. The noise causes of the video images in many 120 ambulance vehicle video terminal monitor equipments are analyzed, and the space rigid body model of self-adaptive median noise reduction filter is established to decrease the noises of the video image transmission process. The noise reduction experiment of video images shows that the proposed video median noise reduction algorithm is superior to the traditional adaptive filtering method, because the new method has the superiority of space-time joint noise reduction.
Colored Noise in First-order-like Phase Transition of a Laser System
HE Ying; ZHU Shiqun; LING Yinsheng
2002-01-01
The decoupling theory is employed to analyze the multiplicative colored noise in a single mode laser system. Steady state intensity distribution function is derived when colored noise is included in the laser system. The first-order-like phase transition driven by multiplicative colored noise is investigated and compared with the case of multiplicative white noise. It is shown that the noise correlation time can affect the parameter plane of the first-order-like phase transition. The steady state intensity distributions in a laser system is changed greatly with noise correlation time τ.
Study of active noise control system for a commercial HVAC unit
Devineni, Naga
Acoustic noise is a common problem in everyday life. If the appliances that are present in the work and living areas generate noise then it's a serious problem. One such appliance is the Heating, Ventilation and Air-conditioning system (HVAC) in which blower fan and compressor units are housed together. Operation of a HVAC system creates two kinds of noise. One is the noise due to the air flow and the other is the result of the compressor. Both of them exhibit different signal properties and need different strategies to control them. There has been previous efforts in designing noise control systems that can control noise from the HVAC system. These include passive methods which use sound absorption materials to attenuate noise and active methods which cancel noise by generating anti-noise. Passive methods are effective in limiting the high frequency noise, but are inefficient in controlling low frequency noise from the compressor. Compressor noise is one of the strong low frequency components that propagate through the walls, therefore there is need for deploying active signal processing methods that consider the signal properties into consideration to cancel the noise acoustically. The quasi periodic nature of the compressor noise is exploited in noise modeling which aids in implementing an adaptive linear prediction filter in estimating the anti noise [12]. In this thesis, a multi channel architecture has been studied for a specific HVAC system in order to improve noise cancellation by creating larger quiet zone. In addition to the multi-channel architecture, a real time narrow band Active Noise Control (ANC) was employed to cancel noise under practical conditions.
[Electrochemical disinfection using the gas diffusion electrode system].
Xu, Wen-Ying; Li, Ping; Dong, Bin
2010-01-01
Study on the electrochemical disinfection with the H2O2 produced at the gas diffusion electrode (GDE) prepared from active carbon/ poly-tetrafluoroethylene (PTFE) was performed in the non-membrane cell. The effects of PTFE mass fraction W(PTFE) and content of the pore-forming agent in GDE m(NH4CO3), operating conditions such as pH value and oxygen flow rate Q(o2)) on disinfection were investigated, respectively. The experimental results showed that H2 O2 reached peak production at W(PTFE) of 0.5 in GDE. Addition of the pore-forming agent in the appropriate amount improved the disinfection, and this phenomenon was more obvious at neutral pH than at acidic pH. BET specific area analysis indicated that the average pore size in the membrane electrode first decreased significantly with the increasing amount of pore-forming agent, and then increased moderately. This helped the mass transfer of oxygen at the GDE. Adsorption made little or no progress to kill the bacteria during the electrolysis. Drop of pH value resulted in a rapid rise of the germicidal efficacy. This system had a broad pH coverage: when total bacterial count in raw water was 10(6) CFU x mL(-1), pH 3-10,the germicidal efficacy was greater than 80% after 30 min electrolysis using the GDE with W(Pt) of 3 per thousand as cathode. Increase of the oxygen flow rate Q(o2) within limits had little influence on the production of H2 O2 and the succeeding disinfection. On one hand, resistance of the solution and energy consumption on the disinfection increased at high oxygen flow rate, which gave rise to an increase in the operating cost of disinfection with the GDE system; on the other hand, treatment time could be reduced reasonably at high oxygen flow rate, which leads to reduction of equipment investment. Killing mechanism study showed that the direct oxidation and formation of the free radicals at the anode played a greater role in the beginning, and then the oxidative indirect effect of the generated H2 O2 at
Noise and signal interference in optical fiber transmission systems an optimum design approach
Bottacchi, Stefano
2008-01-01
A comprehensive reference to noise and signal interference in optical fiber communications Noise and Signal Interference in Optical Fiber Transmission Systems is a compendium on specific topics within optical fiber transmission and the optimization process of the system design. It offers comprehensive treatment of noise and intersymbol interference (ISI) components affecting optical fiber communications systems, containing coverage on noise from the light source, the fiber and the receiver. The ISI is modeled with a statistical approach, leading to new useful computational m
Chaotic system for the detection of periodic signals under the background of strong noise
无
2003-01-01
We propose a method to study the chaotic system for the detection of periodic signals in the presence of strong background noise. The numerical experiments indicate that the chaotic system constructed from the modified Duffing-Holmes equation is sensitive to the weak periodic signal mixed with noise, and it has certain immunity to noise. The signal to noise ratio for the system can reach to about -91 dB.
Using Kalman filters to reduce noise from RFID location system.
Abreu, Pedro Henriques; Xavier, José; Silva, Daniel Castro; Reis, Luís Paulo; Petry, Marcelo
2014-01-01
Nowadays, there are many technologies that support location systems involving intrusive and nonintrusive equipment and also varying in terms of precision, range, and cost. However, the developers some time neglect the noise introduced by these systems, which prevents these systems from reaching their full potential. Focused on this problem, in this research work a comparison study between three different filters was performed in order to reduce the noise introduced by a location system based on RFID UWB technology with an associated error of approximately 18 cm. To achieve this goal, a set of experiments was devised and executed using a miniature train moving at constant velocity in a scenario with two distinct shapes-linear and oval. Also, this train was equipped with a varying number of active tags. The obtained results proved that the Kalman Filter achieved better results when compared to the other two filters. Also, this filter increases the performance of the location system by 15% and 12% for the linear and oval paths respectively, when using one tag. For a multiple tags and oval shape similar results were obtained (11-13% of improvement).
Impact of plasma noise on a direct thrust measurement system
Pottinger, S. J.; Lamprou, D.; Knoll, A. K.; Lappas, V. J.
2012-03-01
In order to evaluate the accuracy and sensitivity of a pendulum-type thrust measurement system, a linear variable differential transformer (LVDT) and a laser optical displacement sensor have been used simultaneously to determine the displacement resulting from an applied thrust. The LVDT sensor uses an analog interface, whereas the laser sensor uses a digital interface to communicate the displacement readings to the data acquisition equipment. The data collected by both sensors show good agreement for static mass calibrations and validation with a cold gas thruster. However, the data obtained using the LVDT deviate significantly from that of the laser sensor when operating two varieties of plasma thrusters: a radio frequency (RF) driven plasma thruster, and a DC powered plasma thruster. Results establish that even with appropriate shielding and signal filtering the LVDT sensor is subject to plasma noise and radio frequency interactions which result in anomalous thrust readings. Experimental data show that the thrust determined using the LVDT system in a direct current plasma environment and a RF discharge is approximately a factor of three higher than the thrust values obtained using a laser sensor system for the operating conditions investigated. These findings are of significance to the electric propulsion community as LVDT sensors are often utilized in thrust measurement systems and accurate thrust measurement and the reproducibility of thrust data is key to analyzing thruster performance. Methods are proposed to evaluate system susceptibility to plasma noise and an effective filtering scheme presented for DC discharges.
Deng, T.; Sun, Z.; Li, G.; Chen, J.; Chen, D.; Wang, J.
2017-02-01
This paper presents a microelectromechanical system (MEMS)-based electrochemical seismic sensor with an anode and a cathode integrated on a single chip. The proposed approach decreases the number of requested wafers as the sensing unit from seven to two. In addition, no alignment and no bonding among the electrodes are needed, significantly simplifying the fabrication process. The experimental results indicate that the proposed device produced a sensitivity of 5771.7 V (m s-1)-1 at 1.4 Hz and a noise level of -163 dB (i.e. 7.1 (nm s-1)/Hz1/2) at 1 Hz. Moreover, the proposed device effectively responds to random ground motions, enabling the detection of low-frequency seismic motions caused by earthquake events.
Bayesian robot system identification with input and output noise.
Ting, Jo-Anne; D'Souza, Aaron; Schaal, Stefan
2011-01-01
For complex robots such as humanoids, model-based control is highly beneficial for accurate tracking while keeping negative feedback gains low for compliance. However, in such multi degree-of-freedom lightweight systems, conventional identification of rigid body dynamics models using CAD data and actuator models is inaccurate due to unknown nonlinear robot dynamic effects. An alternative method is data-driven parameter estimation, but significant noise in measured and inferred variables affects it adversely. Moreover, standard estimation procedures may give physically inconsistent results due to unmodeled nonlinearities or insufficiently rich data. This paper addresses these problems, proposing a Bayesian system identification technique for linear or piecewise linear systems. Inspired by Factor Analysis regression, we develop a computationally efficient variational Bayesian regression algorithm that is robust to ill-conditioned data, automatically detects relevant features, and identifies input and output noise. We evaluate our approach on rigid body parameter estimation for various robotic systems, achieving an error of up to three times lower than other state-of-the-art machine learning methods.
Noise-induced transitions and resonant effects in nonlinear systems
Zaikin, Alexei
2003-02-01
Our every-day experience is connected with different acoustical noise or music. Usually noise plays the role of nuisance in any communication and destroys any order in a system. Similar optical effects are known: strong snowing or raining decreases quality of a vision. In contrast to these situations noisy stimuli can also play a positive constructive role, e.g. a driver can be more concentrated in a presence of quiet music. Transmission processes in neural systems are of especial interest from this point of view: excitation or information will be transmitted only in the case if a signal overcomes a threshold. Dr. Alexei Zaikin from the Potsdam University studies noise-induced phenomena in nonlinear systems from a theoretical point of view. Especially he is interested in the processes, in which noise influences the behaviour of a system twice: if the intensity of noise is over a threshold, it induces some regular structure that will be synchronized with the behaviour of neighbour elements. To obtain such a system with a threshold one needs one more noise source. Dr. Zaikin has analyzed further examples of such doubly stochastic effects and developed a concept of these new phenomena. These theoretical findings are important, because such processes can play a crucial role in neurophysics, technical communication devices and living sciences. Unsere alltägliche Erfahrung ist mit verschiedenen akustischen Einfluessen wie Lärm, aber auch Musik verbunden. Jeder weiss, wie Lärm stören kann und Kommunikation behindert oder gar unterbindet. Ähnliche optische Effekte sind bekannt: starkes Schneetreiben oder Regengüsse verschlechtern die Sicht und lassen uns Umrisse nur noch schemenhaft erkennen. Jedoch koennen ähnliche Stimuli auch sehr positive Auswirkungen haben: Autofahrer fahren bei leiser Musik konzentrierter -- die Behauptung von Schulkindern, nur bei dröhnenden Bässen die Mathehausaufgaben richtig rechnen zu können, ist allerdings nicht wissenschaftlich
Entanglement dynamics of two-qubit systems in different quantum noises
Pan Chang-Ning; Li-Fei; Fang Jian-Shu; Fang Mao-Fa
2011-01-01
The entanglement dynamics of two-qubit systems in different quantum noises are investigated by means of the operator-sum representation method. We find that, except for the amplitude damping and phase damping quantum noise, the sudden death of entanglement is always observed in different two-qubit systems with generalized amplitude damping and depolarizing quantum noise.
Increased noise signal processing in incoherent radar systems
I. I. Chesanovskyi
2013-09-01
Full Text Available Introduction. The work is devoted to the method of increasing coherence and noise immunity pulse radar systems with incoherent sources probing signals. Problem. Incongruities between a resolution and a range of pulsed radar systems can not be resolved within the classical approaches of building incoherent radar systems, requiring new approaches in their construction. The main part. The paper presents a method of two-stage processing incoherent pulsed radar signals, allowing to compensate and use the information available to them and the angular amplitude of spurious modulation. Conclusions. Simulation results and research functions of these expressions of uncertainty indicate that use volatility as an additional transmitter modulation allows to significantly improve the resolution and robustness of the radar system.
Nonlinear Phase Noise Compensation in Experimental WDM Systems with 256QAM
Yankov, Metodi Plamenov; Da Ros, Francesco; Porto da Silva, Edson
2016-01-01
Nonlinear phase noise (NLPN) is studied in an experimental wavelength division multiplexed (WDM) system operating at 256QAM. Extremely narrow linewidth lasers (phase part of the nonlinear noise in a Raman amplified link. Based...
Phase noise approximation analysis for the OFDM system
无
2007-01-01
The influence of phase noise (PN) present at the access point (AP) and mobile terminator (MT) may degrade the performance in orthogonal frequency division multiplexing (OFDM) system, because the OFDM system is sensitive to the PN.The method of PN approximation based on the PN power spectrum was proposed to combat the influence of the PN present.The idea of the PN cancellation is the PN is approximated for the sum of the different frequency between the AP and the MT as well as Doppler shift supposing that the fixed different frequency during several OFDM symbols are identical, so the variable phase may be considered as the combination of the fixed partition and the random partition.The approximation method is utilized to remove the fixed and the random phase partition so that the signal-to-noise ratio (SNR) may be improved.The analysis and the simulation proposed show that the method may effectively improve the performance of the OFDM system.
Sanchez, A.; Sanjurjo, M.; Bouzada, F.; Urrejola, S.
2005-07-01
Given that the experimental signals obtained in an electrochemical noise measurement, ENM, are recorded over a discrete time period, the most direct way of analysing them will be in the time domain resorting to starting to statistical methods. These can be classified into two groups according to use; those which attempt to quantify the degree of the corrosion process (standard deviations, statistical power); and those which attempt to provide information on the corrosion mechanism (based on the assumption that the shape of the time records is a reflection of itself). Among the later the use of the average, the skewness and the kurtosis of the signals or the pitting index can be pointed out as being able to reflect the changes in the corrosion mechanism. Noise resistance stands out above all these parameters. In this work has undertaken the statistical treatment of ENM data obtained by subjecting aluminium to three electrolytes that provoke several types of corrosion in it: passivity, pitting corrosion and generalized corrosion. (Author) 22 refs.
EFFECTS OF COLOURED NOISE IN A TWO-MODE LASER SYSTEM
罗晓琴; 朱士群; 高伟建
2001-01-01
A homogeneously broadened two-mode laser system with multiplicative coloured noise is investigated when the mode coupling constant ξ=2. An analytical result is obtained when two-dimensional decoupling theory is applied to the system. The intensity auto-correlation function and effective eigenvalue of the laser system are calculated when the difference of pump parameters, multiplicative noise strength and noise correlation time are varied. It is shown that the multiplicative noise can enhance the fluctuations while the noise colour can reduce the fluctuations in the laser system.
A HIGH STABILITY, LOW NOISE RF DISTRIBUTION SYSTEM
Bernstein, Dorel
2002-08-20
Next generation linear colliders require high stability, low noise distribution of RF phase and timing signals. We describe a fiber-optics system that transmits phase at 357MHz, at a 1500nm wavelength, over a distance of 15 kilometers. Phase length errors in the transmission fiber are measured using the phase of the signal reflected from the fiber end. Corrections are performed by controlling the temperature of a 6-kilometer fiber spool placed in series with the main transmission fiber. This system has demonstrated a phase stability better than 10 femtoseconds per degree C, per kilometer, an improvement of a factor of >2000 relative to un-stabilized fiber. This system uses standard low cost telecom fiber and components.
Synchronization between two different noise-perturbed chaotic systems with unknown parameters
Jia, Fei-Lei; Xu, Wei; Du, Lin
2007-11-01
In this paper, a general method of synchronizing noise-perturbed chaotic systems with unknown parameters is proposed. Based on the LaSalle-type invariance principle for stochastic differential equations and by employing a combination of feedback control and adaptive control, some sufficient conditions of chaos synchronization between these noise-perturbed systems with unknown parameters are established. The model used in the research is the chaotic system, but the method is also applicable to the hyperchaotic systems. Unified system and noise-perturbed Rössler system, hyperchaotic Chen system and noise-perturbed hyperchaotic Rössler system are taken for illustrative examples to demonstrate this technique.
A New Dual-electrode and Multi-channel Electrochemical DetectionSystem for Capillary Electrophoresis
Bing Yi YANG; Jin Yuan MO; Rong LAI
2004-01-01
A new type of dual-electrode and multi-channel electrochemical detection technology for capillary electrophoresis is described in this paper. Two detectors(the amperometric detector and the conductometric detector)or two conductometric detectors are connected to the same capillary electrophoresis system. The whole system possesses the advantages of the two electrochemical detectors including sparing time,improving the analytical speed and expanding the sample range.The working electrode and detector cell are handled easily.The system was applied to sample detection with satisfactory results.
An RF tag communication system model for noise radar
Pan, Qihe; Narayanan, Ram M.
2008-04-01
RF (radio-frequency) tags have drawn increasing research interest because of their great potential uses in many radio frequency identification applications. They can also be configured to work with radar as a communication channel by receiving radar acquisition signals, suitably coding these, and retransmitting them back to the radar. This paper proposes a system model for the communication between a noise radar and multiple RF tags. The radar interrogates the RF tags in a region of interest by sending ultrawideband noise signals. Upon receiving the radar's signal, all the tags within the radar's range wake up, and respond to the radar with simple messages. The RF tag filters the radar signal to a unique spectral band, which represents its identification information, and different RF tags occupy different non-overlapping bands of the spectrum of the radar signal. Tag messages are modulated onto the waveform through taps of weighted delays. The radar decodes the RF tag identifications and corresponding messages by cross-correlating the RF tag returned signals with the replica of the radar transmitted signal. Calculations and simulation results both show that the proposed system is capable of communicating simple messages between RF tags and radar.
Air-borne noise of thermal module and system for notebook personal computers:experimental study
2008-01-01
Thermal performance is the most important issue to be considered when a thermal module is designed for a notebook personal computer (PC).Because the fan causes air-borne noise and affects the user's comfort,the acoustic characteristics of the module attract more attention.Experiments were conducted to study the noise sources,the noise characteristic and the main factors influencing the noise level.The difference between the air-borne noise of the thermal module and the whole computer system was analyzed and its propagating characteristics were derived.The influence of I/O ports on the air-borne noise was also studied experimentally.
Kharchenko, D. O.
For the system with colored multiplicative noise the nonlinearity of the synergetic potential like φ^{2+m} model in Langevin equation was shown to be capable of providing the expanse of the stochastic system phase space. The concrete system of the population dynamics with the noise correlation time τ_cto∞ is examined. The fractal dimension of that kind of a system is defined as D=m, in contrast to the system with a white noise were D=0.
A New PC and LabVIEW Package Based System for Electrochemical Investigations.
Stević, Zoran; Andjelković, Zoran; Antić, Dejan
2008-03-15
The paper describes a new PC and LabVIEW software package based system forelectrochemical research. An overview of well known electrochemical methods, such aspotential measurements, galvanostatic and potentiostatic method, cyclic voltammetry andEIS is given. Electrochemical impedance spectroscopy has been adapted for systemscontaining large capacitances. For signal generation and recording of the response ofinvestigated electrochemical cell, a measurement and control system was developed, basedon a PC P4. The rest of the hardware consists of a commercially available AD-DA converterand an external interface for analog signal processing. The interface is a result of authorsown research. The software platform for desired measurement methods is LabVIEW 8.2package, which is regarded as a high standard in the area of modern virtual instruments. Thedeveloped system was adjusted, tested and compared with commercially available systemand ORCAD simulation.
Synchronization of uncoupled excitable systems induced by white and coloured noise
Zambrano, Samuel; Marino, Ines P; Seoane, Jesus M; Sanjuan, Miguel A F [Nonlinear Dynamics, Chaos and Complex Systems Group, Departamento de Fisica, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain); Euzzor, Stefano; Geltrude, Andrea; Meucci, Riccardo; Arecchi, Fortunato T, E-mail: samuel.zambrano@urjc.e, E-mail: jesus.seoane@urjc.e, E-mail: ines.perez@urjc.e [CNR-Istituto Nazionale di Ottica Applicata, Largo E Fermi, 6 50125 Firenze (Italy)
2010-05-15
We study, both numerically and experimentally, the synchronization of uncoupled excitable systems due to a common noise. We consider two identical FitzHugh-Nagumo systems, which display both spiking and non-spiking behaviours in chaotic or periodic regimes. An electronic circuit provides a laboratory implementation of these dynamics. Synchronization is tested with both white and coloured noise, showing that coloured noise is more effective in inducing synchronization of the systems. We also study the effects on the synchronization of parameter mismatch and of the presence of intrinsic (not common) noise, and we conclude that the best performance of coloured noise is robust under these distortions.
High-power electrochemical energy storage system employing stable radical pseudocapacitors.
Maruyama, Hitoshi; Nakano, Hideyuki; Nakamoto, Masaaki; Sekiguchi, Akira
2014-01-27
The development of electrical energy storage devices that can operate at high charge and discharge rates is fundamentally important, however although electrochemical capacitors (ECs) can charge and discharge at high rates, their electrochemical storage capacity remains an order of magnitude lower than that of conventional lithium-ion batteries. Novel pseudocapasitors are developed, based on the stable persilyl-susbtituted free radicals of the heavy group 14 elements, (tBu2 MeSi)3 E(.) [E=Si (1), Ge (2), and Sn (3)], as anode materials for energy storage system. Such systems showed a remarkable cycle stability without significant loss of power density, in comparison with similar characteristics of the known organic radical batteries, the dual carbon cell, and the electrochemical capacitor. Particularly important is that these novel electrochemical energy storage systems employing stable heavy group 14 element radicals are lithium-free. The electrochemical properties and structures of the reduced and oxidized species were studied by the cyclic voltammetry (CV), electron paramagnetic resonance (EPR) spectroscopy, and X-ray diffraction (XRD).
Shanmugavadivu, P.; Eliahim Jeevaraj, P. S.
2014-06-01
The Adaptive Iterated Functions Systems (AIFS) Filter presented in this paper has an outstanding potential to attenuate the fixed-value impulse noise in images. This filter has two distinct phases namely noise detection and noise correction which uses Measure of Statistics and Iterated Function Systems (IFS) respectively. The performance of AIFS filter is assessed by three metrics namely, Peak Signal-to-Noise Ratio (PSNR), Mean Structural Similarity Index Matrix (MSSIM) and Human Visual Perception (HVP). The quantitative measures PSNR and MSSIM endorse the merit of this filter in terms of degree of noise suppression and details/edge preservation respectively, in comparison with the high performing filters reported in the recent literature. The qualitative measure HVP confirms the noise suppression ability of the devised filter. This computationally simple noise filter broadly finds application wherein the images are highly degraded by fixed-value impulse noise.
Stochastic resonance in a bias linear system with multiplicative and additive noise
Guo Feng; Zhou Yu-Rong; Jiang Shi-Qi; Gu Tian-Xiang
2006-01-01
In this paper, the stochastic resonance in a bias linear system subjected multiplicative and additive dichotomous noise is investigated. Using the linear-response theory and the properties of the dichotomous noise, this paper finds the exact expressions for the first two moments and the signal-to-noise ratio (SNR). It is shown that the SNR is a non-monotonic function of the correlation time of the multiplicative and additive noise, and it varies non-monotonously with the intensity and asymmetry of the multiplicative noise as well as the external field frequency. Moreover, the SNR depends on the system bias, the intensity of the cross noise between the multiplicative and additive noise, and the strength and asymmetry of the additive noise.
Favazza, Christopher P; Yu, Lifeng; Leng, Shuai; Kofler, James M; McCollough, Cynthia H
2015-01-01
To compare computed tomography dose and noise arising from use of an automatic exposure control (AEC) system designed to maintain constant image noise as patient size varies with clinically accepted technique charts and AEC systems designed to vary image noise. A model was developed to describe tube current modulation as a function of patient thickness. Relative dose and noise values were calculated as patient width varied for AEC settings designed to yield constant or variable noise levels and were compared to empirically derived values used by our clinical practice. Phantom experiments were performed in which tube current was measured as a function of thickness using a constant-noise-based AEC system and the results were compared with clinical technique charts. For 12-, 20-, 28-, 44-, and 50-cm patient widths, the requirement of constant noise across patient size yielded relative doses of 5%, 14%, 38%, 260%, and 549% and relative noises of 435%, 267%, 163%, 61%, and 42%, respectively, as compared with our clinically used technique chart settings at each respective width. Experimental measurements showed that a constant noise-based AEC system yielded 175% relative noise for a 30-cm phantom and 206% relative dose for a 40-cm phantom compared with our clinical technique chart. Automatic exposure control systems that prescribe constant noise as patient size varies can yield excessive noise in small patients and excessive dose in obese patients compared with clinically accepted technique charts. Use of noise-level technique charts and tube current limits can mitigate these effects.
Automatic classification of urban traffic noise onboard an acoustic monitoring system
Wessels, P.W.; Zon, A.T. van; Basten, T.G.H.
2013-01-01
Recent developments in acoustic monitoring systems make it possible to measure complex noise situations, like urban traffic noise, continuously. Monitoring provides more insight in the noise situation, from which more specific and (cost) effective measures can be taken. Monitoring also allows direct
Receiver design of UWB radio systems for an impulsive noise environment
贾琳; 张中兆
2004-01-01
The performance of UWB (uhrawide bandwidth) radio systems under an impulsive noise environment is first investigated. In the analysis, the Middleton's class A model is used as a model of the impulsive noise. At first, the statistical characteristics of the in-phase and quadrature components of the impulsive noise are investigated, and it is proved that unlike Gaussian noise, these components are dependent especially on the impulsive noise with small impulsive indices. The probability that the high amplitude noise is emitted in the in-phase component which becomes firstly larger and then smaller for the larger quadrature component of impulsive noise is presented. Next, the performance of conventional UWB radio systems designed for the Gaussian noise under the impulsive noise is evaluated and numerical results show that the performance of the conventional UWB radio systems is much degraded by the effect of the impulsive noise.Using the dependence between the in-phase and quadrature components of the impulsive noise, a novel UWB receiver designed for impulsive noise is proposed and the performance improvement achieved by the receiver is evaluated. Numerical results show that the performance of UWB radio systems is much improved by employing the proposed receiver.
Automatic classification of urban traffic noise onboard an acoustic monitoring system
Wessels, P.W.; Zon, A.T. van; Basten, T.G.H.
2013-01-01
Recent developments in acoustic monitoring systems make it possible to measure complex noise situations, like urban traffic noise, continuously. Monitoring provides more insight in the noise situation, from which more specific and (cost) effective measures can be taken. Monitoring also allows direct
BWR online monitoring system based on noise analysis
Ortiz-Villafuerte, Javier [Departamento de Sistemas Nucleares, Instituto Nacional de Investigaciones Nucleares, Carr. Mexico-Toluca S/N, Ocoyoacac, Edo. de Mexico, 52750 (Mexico)]. E-mail: jov@nuclear.inin.mx; Castillo-Duran, Rogelio [Departamento de Sistemas Nucleares, Instituto Nacional de Investigaciones Nucleares, Carr. Mexico-Toluca S/N, Ocoyoacac, Edo. de Mexico, 52750 (Mexico)]. E-mail: rcd@nuclear.inin.mx; Alonso, Gustavo [Departamento de Sistemas Nucleares, Instituto Nacional de Investigaciones Nucleares, Carr. Mexico-Toluca S/N, Ocoyoacac, Edo. de Mexico, 52750 (Mexico)]. E-mail: galonso@nuclear.inin.mx; Calleros-Micheland, Gabriel [Central Nuclear de Laguna Verde, Comision Federal de Electricidad, Carr. Cardel-Nautla, km. 42.5, Alto Lucero, Veracruz (Mexico)]. E-mail: gcm9acpp@cfe.gob.mx
2006-11-15
A monitoring system for during operation early detection of an anomaly and/or faulty behavior of equipment and systems related to the dynamics of a boiling water reactor (BWR) has been developed. The monitoring system is based on the analysis of the 'noise' or fluctuations of a signal from a sensor or measurement device. An efficient prime factor algorithm to compute the fast Fourier transform allows the continuous, real-time comparison of the normalized power spectrum density function of the signal against previously stored reference patterns in a continuously evolving matrix. The monitoring system has been successfully tested offline. Four examples of the application of the monitoring system to the detection and diagnostic of faulty equipment behavior are presented in this work: the detection of two different events of partial blockage at the jet pump inlet nozzle, miss-calibration of a recirculation mass flow sensor, and detection of a faulty data acquisition card. The events occurred at the two BWR Units of the Laguna Verde Nuclear Power Plant. The monitoring system and its possible coupling to the data and processing information system of the Laguna Verde Nuclear Power Plant are described. The signal processing methodology is presented along with the introduction of the application of the evolutionary matrix concept for determining the base signature of reactor equipment or component and the detection of off normal operation conditions.
Integrated Electrochemical Analysis System with Microfluidic and Sensing Functions
Hiroaki Suzuki
2008-02-01
Full Text Available An integrated device that carries out the timely transport of solutions andconducts electroanalysis was constructed. The transport of solutions was based oncapillary action in overall hydrophilic flow channels and control by valves that operateon the basis of electrowetting. Electrochemical sensors including glucose, lactate,glutamic oxaloacetic transaminase (GOT, glutamic pyruvic transaminase (GPT, pH,ammonia, urea, and creatinine were integrated. An air gap structure was used for theammonia, urea, and creatinine sensors to realize a rapid response. To enhance thetransport of ammonia that existed or was produced by the enzymatic reactions, the pHof the solution was elevated by mixing it with a NaOH solution using a valve based onelectrowetting. The sensors for GOT and GPT used a freeze-dried substrate matrix torealize rapid mixing. The sample solution was transported to required sensing sites atdesired times. The integrated sensors showed distinct responses when a sample solutionreached the respective sensing sites. Linear relationships were observed between theoutput signals and the concentration or the logarithm of the concentration of theanalytes. An interferent, L-ascorbic acid, could be eliminated electrochemically in thesample injection port.
Modeling noise-induced resonance in an excitable system: an alternative approach.
Nurujjaman, Md
2010-03-01
Recently, it has been observed [Md. Nurujjaman, Phy. Rev. E 80, 015201(R) (2009)] that in an excitable system, one can maintain noise-induced coherency in the coherence resonance by blocking the destructive effect of the noise on the system at higher noise level. This phenomenon of constant coherence resonance (CCR) cannot be explained by the existing way of simulation of the model equations of an excitable system with added noise. In this paper, we have proposed a general model which explains the noise-induced resonance phenomenon CCR as well as coherence resonance (CR) and stochastic resonance (SR). The simulation has been carried out considering the basic mechanism of noise-induced resonance phenomena: noise only perturbs the system control parameter to excite coherent oscillations, taking proper precautions so that the destructive effect of noise does not affect the system. In this approach, the CR has been obtained from the interference between the system output and noise and the SR has been obtained by adding noise and a subthreshold signal. This also explains the observation of the frequency shift of coherent oscillations in the CCR with noise level.
Chen, Gang; Lin, Yuehe
2008-07-20
Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.
Filtering for linear systems with noise correlation and its application to singular systems
Wu Jian-Rong; Song Shi-Ji
2004-01-01
In this paper, an optimal filter for a stochastic linear system with previous stage noise correlation is designed.Based on this result, together with the decomposition techniques of the stochastic singular linear system, the design of an optimal filter for a stochastic singular linear system is given.
Identification and reduction of vibration and noise of a glass tempering system
Ashhab, M. S.
2015-05-01
The vibration and noise of a glass tempering machine at a factory are studied. Experiments were conducted to identify the sources of vibration and noise. It was found that main sources for vibration and noise are two air barrels, the air pipes from the fans to the glass tempering machine and the fans location. Solutions were suggested to reduce vibration and noise from these three main sources. One of the solutions that were implemented is placing rubber dampers beneath the air barrels and pipes which almost cancelled the horizontal vibrations in the building structure and reduced the vertical vibrations to a low value most likely coming from noise. There are two types of noise, namely, radiation noise from the fans through the fans room walls and transmitted noise through the pipes caused by turbulence. A glass wool noise insulating layer was installed on the wall between the fans room and factory to reduce radiation noise through this wall. Part of the air pipe system in the factory is made of a light material which produced the highest levels of noise above 110 dBA. These air pipes were wrapped by glass wool rolls and the noise level near them was reduced to below 100 dBA which comes from other machine parts. In addition, noise levels were reduced between 2 and 15 dBA at different points in the factory.
Robust terahertz self-heterodyne system using a phase noise compensation technique.
Song, Hajun; Song, Jong-In
2015-08-10
We propose and demonstrate a robust terahertz self-heterodyne system using a phase noise compensation technique. Conventional terahertz self-heterodyne systems suffer from degraded phase noise performance due to phase noise of the laser sources. The proposed phase noise compensation technique uses an additional photodiode and a simple electric circuit to produce phase noise identical to that observed in the terahertz signal produced by the self-heterodyne system. The phase noise is subsequently subtracted from the terahertz signal produced by the self-heterodyne system using a lock-in amplifier. While the terahertz self-heterodyne system using a phase noise compensation technique offers improved phase noise performance, it also provides a reduced phase drift against ambient temperature variations. The terahertz self-heterodyne system using a phase noise compensation technique shows a phase noise of 0.67 degree in terms of a standard deviation value even without using overall delay balance control. It also shows a phase drift of as small as approximately 10 degrees in an open-to-air measurement condition without any strict temperature control.
Colored Noise Induced Bistable Switch in the Genetic Toggle Switch Systems.
Wang, Pei; Lü, Jinhu; Yu, Xinghuo
2015-01-01
Noise can induce various dynamical behaviors in nonlinear systems. White noise perturbed systems have been extensively investigated during the last decades. In gene networks, experimentally observed extrinsic noise is colored. As an attempt, we investigate the genetic toggle switch systems perturbed by colored extrinsic noise and with kinetic parameters. Compared with white noise perturbed systems, we show there also exists optimal colored noise strength to induce the best stochastic switch behaviors in the single toggle switch, and the best synchronized switching in the networked systems, which demonstrate that noise-induced optimal switch behaviors are widely in existence. Moreover, under a wide range of system parameter regions, we find there exist wider ranges of white and colored noises strengths to induce good switch and synchronization behaviors, respectively; therefore, white noise is beneficial for switch and colored noise is beneficial for population synchronization. Our observations are very robust to extrinsic stimulus strength, cell density, and diffusion rate. Finally, based on the Waddington's epigenetic landscape and the Wiener-Khintchine theorem, physical mechanisms underlying the observations are interpreted. Our investigations can provide guidelines for experimental design, and have potential clinical implications in gene therapy and synthetic biology.
Cheng, Chaojun; Zhou, Bingchang; Gao, Xiao; McDonnell, Mark D.
2017-08-01
We investigate multilevel threshold systems with signal-dependent noise that transmit a common random input signal. We demonstrate the occurrence of M-ary suprathreshold stochastic resonance caused by the signal-dependent noise, and quantify the information enhancement that results relative to the absence of noise. We also find that in the case of M-ary threshold systems, the values of mutual information and signal-to-quantization-noise ratio are larger than the corresponding values in the case of binary threshold systems. These results are potentially useful for understanding the encoding mechanism of inner-ear hair cells and other biological sensory systems.
Gas-permeable hydrophobic tubular membranes for ammonia recovery in bio-electrochemical systems
Kuntke, P.; Zamora, P.; Saakes, M.; Buisman, C.J.N.; Hamelers, H.V.M.
2016-01-01
The application of a gas-permeable hydrophobic tubular membrane in bio-electrochemical systems enables efficient recovery of ammonia (NH3) from their cathode compartments. Due to a hydrogen evolution reaction at the cathode, no chemical addition was required to increase the pH for continuous NH3
Self-organization in electrochemical systems II spatiotemporal patterns and control of chaos
Orlik, Marek
2014-01-01
The second of two volumes, this book covers self-organisation and non-linear dynamics in electrochemical systems. Each description includes an introduction to basic concepts of nonlinear dynamics, helping the reader to a deeper understanding of core concepts.
Orlik, Marek
2014-01-01
This is the first of two volumes covering self-organisation and non-linear dynamics in electrochemical systems. Each description includes an introduction to basic concepts of nonlinear dynamics, helping the reader to a deeper understanding of the topic.
Huang, Yu-Xi; Liu, Xian-Wei; Xie, Jia-Fang; Sheng, Guo-Ping; Wang, Guan-Yu; Zhang, Yuan-Yuan; Xu, An-Wu; Yu, Han-Qing
2011-05-28
Bridging microbes and electrode to facilitate the extracellular electron transfer (EET) is crucial for bio-electrochemical systems (BESs). Here, a significant enhancement of the EET process was achieved by biomimetically fabricating a network structure of graphene oxide nanoribbons (GONRs) on the electrode. This strategy is universal to enhance the adaptability of GONRs at the bio-nano interface to develop new bioelectronic devices.
Bohm, S.; Olthuis, Wouter; Bergveld, Piet
2000-01-01
In this contribution a micro liquid dosing system is presented, which allows bi-directional manipulation of fluids (i.e. pushing out and pulling in of liquids) by the electrochemical generation and removal of gas bubbles. Bi-directionality is obtained by reversal of the actuation current thereby
1990-01-01
Acad. Tokyo, Japan 15: 39- 26. Frumkin, A. N., Slygin, A., 1953. Acta Physicochim. URSS 3: 791- 27. Vetter, K. J. 1967. Electrochemical Kinetics...CA 93940 China Lake, CA 93555 A-TN: Mechanical Engineering ATTN: Library Department 1 Naval Air Systems Command NASA Washington, DC 20360 Lewis
Ivashina, M V; Bakker, L; Witvers, R H
2011-01-01
The purpose of this report is to document the noise performance of a complex beamforming array antenna system and to characterize the recently developed noise measurement facility called THACO, which was developed at ASTRON. The receiver system includes the array antenna of strongly coupled 144 TSA elements, 144 Low Noise Amplifiers (LNAs) (Tmin =35-40K) and the data recording/storing facilities of the initial test station that allow for off-line digital beamforming. The primary goal of this study is to compare the measured receiver noise temperatures with the simulated values for several practical beamformers, and to predict the associated receiver noise coupling contribution, antenna thermal noise and ground noise pick-up (due to the back radiation).
Espada, L.; Sanjurjo, M.; Urrejola, S.; Bouzada, F.; Rey, G.; Sanchez, A.
2003-07-01
Given its simplicity and low cost compared to other types of methodologies, the measurement and interpretation of Electrochemical Noise, is consolidating itself as one of the analysis methods most frequently used for the interpretation of corrosion. As the technique is still evolving, standard treatment methodologies for data retrieved in experiments do not exist yet. To date, statistical analysis and the Fourier analysis are commonly used in order to establish the parameters that may characterize the recording of potential and current electrochemical noise. This study introduces a new methodology based on wavelet analysis and presents its advantages with regards to the Fourier analysis in distinguishes periodical and non-periodical variations in the signal power in time and frequency, as opposed to the Fourier analysis that only considers the frequency. (Author) 15 refs.
SUBSPACE-BASED NOISE VARIANCE AND SNR ESTIMATION FOR MIMO OFDM SYSTEMS
无
2006-01-01
This paper proposes a subspace-based noise variance and Signal-to-Noise Ratio (SNR) estimation algorithm for Multi-Input Multi-Output (MIMO) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems. The special training sequences with the property of orthogonality and phase shift orthogonality are used in pilot tones to obtain the estimated channel correlation matrix. Partitioning the observation space into a delay subspace and a noise subspace, we achieve the measurement of noise variance and SNR.Simulation results show that the proposed estimator can obtain accurate and real-time measurements of the noise variance and SNR for various multipath fading channels, demonstrating its strong robustness against different channels.
Weighted-noise threshold based channel estimation for OFDM systems
Pallaviram Sure; Chandra Mohan Bhuma
2015-10-01
Orthogonal frequency division multiplexing (OFDM) technology is the key to evolving telecommunication standards including 3GPP-LTE Advanced and WiMAX. Reliability of any OFDM system increases with improvedmean square error performance (MSE) of its channel estimator (CE). Particularly, a least squares (LS) based CE incorporating a time-domain denoising threshold, enables better MSE performance, while avoiding the need for a-priori knowledge of channel statistics (KCS). Existing optimal time-domain thresholds exhibit suboptimal behavior for completely unavailable KCS environments. This is because they involve consistent estimation of one or more KCS parameters, and corresponding estimation errors introduce severe degradation in MSE performance of the CE. To overcome the MSE degradation, this paper proposes a weighted-noise threshold, by introducing a modified hypothesis-testing-problem (HTP) interpretation. Derivation of resulting analytical MSE expression is also provided. Results of OFDM system simulations carried out in rayleigh faded ITU-TU6 and WiMAX-SUI4 channel environments with U-shaped power spectral densities, are presented. The performance results show that, compared to many of the existing thresholds, the proposed threshold renders better MSE performance to the CE and higher reliability to the OFDM system in terms of better bit error rate (BER) performance.
Compact Electrochemical System Using On-Chip Sensor Electrodes and Integrated Devices
Yamazaki, Tomoyuki; Ikeda, Takaaki; Ishida, Makoto; Sawada, Kazuaki
2011-04-01
We report a compact electrochemical sensing system to implement cyclic voltammetry. This type of sensor needs a working electrode, counter electrode, and reference electrode, all of which were integrated on a single chip. The electrochemical system also needs a potentiostat and an input voltage-generating circuit, which were developed using on-chip active devices and a few discrete passive components. This is the first sensor system incorporating electrode-side input voltage generation for electrochemical measurements using an on-chip operational amplifier, which replaces a bulky external voltage controller. A continuous cyclic voltammetry measurement was conducted with a well-studied ferricyanide solution to demonstrate the operation of the intelligent sensor chip. A clear peak was observed and linearity to the target chemical concentration was obtained between the peak height and concentration of the ferricyanide solution. With potential for mass production and small size, this sensor chip could be the best candidate to realize point-of-care testing. This sensor chip is a milestone of a fully integrated electrochemical sensor chip.
Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.; Mehta, Hardeep S.; Ewing, R James; Ewing, Thomas; Mueller, Karl T.; Beyenal, Haluk
2014-03-01
In order to fully understand electrochemically active biofilms and the limitations to their scale-up in industrial biofilm reactors, a complete picture of the microenvironments inside the biofilm is needed. Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for non-invasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live electrochemically active biofilms. Here, we introduce a novel biofilm microreactor system that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radiofrequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system, we grew Geobacter sulfurreducens biofilms. NMR was used to investigate growth media flow velocities, which were compared to simulated laminar flow, and electron donor concentrations inside the biofilms. We use Monte Carlo error analysis to estimate standard deviations of the electron donor concentration measurements within the biofilm. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.
Electrochemical disinfection using the gas diffusion electrode system.
Xu, Wenying; Li, Ping; Dong, Bin
2010-01-01
A study on the electrochemical disinfection with H2O2 generated at the gas diffusion electrode (GDE) from active carbon/polytetrafluoroethylene was performed in a non-membrane cell. The effects of Pt load and the pore-forming agent content in GDE, and operating conditions were investigated. The experimental results showed that nearly all bacterial cultures inoculated in the secondary effluent from wastewater treatment plant could be inactivated within 30 min at a current density of 10 mA/cm2. The disinfection improved with increasing Pt load. Addition of the pore-forming agent NH4HCO3 improved the disinfection, while a drop in the pH value resulted in a rapid rise of germicidal efficacy and the disinfection time was shortened with increasing oxygen flow rate. Adsorption was proved to be ineffective in destroying bacteria, while germicidal efficacy increased with current density. The acceleration rate was different, it initially increased with current density. Then decreased, and finally reached a maximum at a current density of 6.7 mA/cm2. The disinfection also improved with decreasing total bacterial count. The germicidal efficacy in the cathode compartment was approximately the same as in the anode compartment, indicating that the contribution of direct oxidation and the indirect treatment of bacterial cultures by hydroxyl radical was similar to the oxidative indirect effect of the generated H2O2.
Seismic ambient noise study at Bouillante geothermal system, French Antilles
Jousset, Philippe; Bitri, Adnan; Loiseau, Justine; Bouchot, Vincent
2010-05-01
Seismic ambient noise analyses have been shown to be able to image structural features of the crust and to monitor underground changes of seismic wave ground velocity. We present results of cross-correlation techniques at Bouillante geothermal field, French Antilles, the largest French high-enthalpy geothermal system exploited for electrical power from 3 collocated productive wells. Two power plants generate electricity and fluid extraction rate varies with time and wells are sometimes closed for equipment maintenance. Under the support of the French Environment and Energy Management Agency (ADEME) and the French Research Agency (ANR), BRGM has been analyzing seismic data from a network comprising 5 broadband seismological stations set-up at Bouillante area since 2004. Amongst the large number of earthquakes recorded, we show that no single earthquake could be related to the fluid exploitation. Instead, they are due to the intense regional seismicity. Despite the small number of stations, surface wave travel times computed from ambient noise cross-correlation for about a year suggest that the velocity structure is consistent with the conceptual model of hot (250°C) and permeable (fractured) geothermal reservoir of Bouillante. We show at several instances that changes of the fluid extraction rate have spatial and temporal slight perturbations on medium wave velocity. For example, when the production stops for maintenance, velocity increases by several percent and with larger amplitude at stations within 1 km distance from the production wells and lower amplitudes (by more than 50 %) at stations further than 2 km from the production wells. In addition, we note that velocity perturbations have a delay of at most 1 day at further stations. We discuss several mechanisms to explain those observations like pressure and stress variations in the geothermal system. The results suggest that the inferred velocity changes, owing the fine sensibility of the inter
Multiple cross-correlation noise induced transition in a stochastic bistable system
Wang, Can-Jun; Yang, Ke-Li; Du, Chun-Yan
2017-03-01
Based on the stochastic equivalent rules, the Fokker-Planck Equation for a general one-dimensional nonlinear system subjected to N-component noises and cross-correlation noises is derived, and the greatest advantage of the method lies in its simplicity. Applying this method, the effects of multiple sources of noise and the correlation forms of noises among them (i.e., two multiplicative noises, an additive noise and the correlation between the three noises) on the steady-state properties and the mean first passage time (MFPT) of a stochastic bistable system are discussed in details. The results show rich transition phenomena, such as the reentrance-like noise-induced phenomenon and the switch between the bimodal and the unimodal structure for different noise intensities. Moreover, the effects of the cross-correlation among the three noise sources on the MFPT are also discussed, and the noise-enhanced stability phenomenon and the resonant activation phenomenon are observed. The numerical results are in basic agreement with the theoretical predictions.
Comparison of Bistable Systems and Matched Filters in Non-Gaussian Noise
Zhang, Xinming; Yan, Jianfeng; Duan, Fabing
2016-10-01
In this paper, we report that for a weak signal buried in the heavy-tailed noise, the bistable system can outperform the matched filter, yielding a higher output signal-to-noise ratio (SNR) or a lower probability of error. Moreover, by adding mutually independent internal noise components to an array of bistable systems, the output SNR or the probability of error can be further improved via the mechanism of stochastic resonance (SR). These comparison results demonstrate the potential capability of bistable systems for detecting weak signals in non-Gaussian noise environments.
Lincheng Zhou
2015-08-01
Full Text Available This paper focuses on the parameter identification problem for Wiener nonlinear dynamic systems with moving average noises. In order to improve the convergence rate, the gradient-based iterative algorithm is presented by replacing the unmeasurable variables with their corresponding iterative estimates, and to compute iteratively the noise estimates based on the obtained parameter estimates. The simulation results show that the proposed algorithm can effectively estimate the parameters of Wiener systems with moving average noises.
1/f noise in spatially extended systems with order-disorder phase transitions
Staliunas, K
1999-01-01
Noise power spectra in spatially extended dynamical systems are investigated, using as a model the Complex Ginzburg-Landau equation with a stochastic term. Analytical and numerical investigations show that the temporal noise spectra are of 1/f^a form, where a=2-D/2 with D the spatial dimension of the system. This suggests that nonequilibrium order-disorder phase transitions may play a role for the universally observed 1/f noise.
Sekiguchi, Y.; Nakanishi, K.; Saruta, S. (Toshiba Corp., Tokyo (Japan))
1991-04-20
Aiming at lowering the noise down to a domestic background noise level, development was made of GR-W40NVI, extra-low-noise refrigerator with an active noise control system. The active control for lowering the noise is methodically to artificially generate sound, reverse in phase against the noise to be generated, silence it by acoustic wave interference, and theoretically reduce the acoustic pressure to zero. Such a technology was applied to the refrigerator morphologically as follows: In order to silence the noise, generated by the compressor and three-dimensionally diffused, by a simple structure, duct structure is applied for the noise to be diffused in one direction only, by acoustically insulating and confining the compressor with exception of its thermal exhaust opening. In order to lower the noise, generated by the compressor and amplified in zonal region, the active control is applied against the low frequency noise, while the conventional acoustic insulation/absorption technology is done against the high frequency noise. In order to quickly and accurately prepare sound, reverse in phase against the noise under fluctuation, signal processing is made by using digital signal processor (DSP), hardware exclusively for it. As a result, the noise was lowered by about 7dB (1/5) for the basic type of refrigerator. 12 figs.
Suppression of fixed pattern noise for infrared image system
Park, Changhan; Han, Jungsoo; Bae, Kyung-Hoon
2008-04-01
In this paper, we propose suppression of fixed pattern noise (FPN) and compensation of soft defect for improvement of object tracking in cooled staring infrared focal plane array (IRFPA) imaging system. FPN appears an observable image which applies to non-uniformity compensation (NUC) by temperature. Soft defect appears glittering black and white point by characteristics of non-uniformity for IR detector by time. This problem is very important because it happen serious problem for object tracking as well as degradation for image quality. Signal processing architecture in cooled staring IRFPA imaging system consists of three tables: low, normal, high temperature for reference gain and offset values. Proposed method operates two offset tables for each table. This is method which operates six term of temperature on the whole. Proposed method of soft defect compensation consists of three stages: (1) separates sub-image for an image, (2) decides a motion distribution of object between each sub-image, (3) analyzes for statistical characteristic from each stationary fixed pixel. Based on experimental results, the proposed method shows an improved image which suppresses FPN by change of temperature distribution from an observational image in real-time.
Noise in Load Cell Signal in an Automatic Weighing System Based on a Belt Conveyor
Kyoo Nam Choi
2017-01-01
Full Text Available Noise in load cell signal in an automatic weighing system based on a belt conveyor has been examined experimentally in time and frequency domains to enhance signal quality. The noise frequency spectrum showed nonlinearly increasing multiple resonance peaks as speed increased. The noise reduction process using noise reduction algorithm, by sharply rejecting peak noise frequency component and afterward forming optimum pulse width ratio through filter slope control using selective switching of 6 LPF stages, was used for enhanced accuracy. The effectiveness of proposed method, controlling both cutoff frequency and slope of LPF, was evaluated by feeding 50 g test mass, and this noise reduction process showed better noise filtering with enhanced accuracy than fixed cutoff frequency control method. The ratio of top to bottom pulse width showed that LPF cutoff frequency above 5 Hz had the ratio above 50% up to 80 m/min speed range.
Effects of cross-correlated noises on the relaxation time of the bistable system
谢崇伟; 梅冬成
2003-01-01
The stationary correlation function and the associated relaxation time for a general system driven by crosscorrelated white noises are derived, by virtue of a Stratonovich-like ansatz. The effects of correlated noises on the relaxation time of a bistable kinetic model coupled to an additive and a multiplicative white noises are studied. It is proved that for small fluctuations the relaxation time Tc as a function of λ (the correlated intensity between noises)exhibits very different behaviours for α＜ D and for α＞ D (α and D, respectively, stand for the intensities of additive and multiplicative noises). When α＞ D, Tc increases with increasing λ. But when α＜ D, Tc increases with λ for the case of weak correlated noises and sharply decreases with λ for the case of strong correlated noises, and thus Tc-λ curve behaves with one extremum.
Xue, Xiaoxiao; Wen, He; Zheng, Xiaoping; Zhang, Hanyi; Guo, Yili; Zhou, Bingkun
2009-02-01
The noise in photonic true time delay systems based on broadband optical source and dispersion components is investigated. It is found that the beat noise induced by the optical source begins to dominate and grows far larger than other noise terms quickly, as long as the detected optical power is above some certain value P(thr). When the system dispersion is nonzero, the output carrier-to-noise ratio (CNR) will change periodically with the optical bandwidth due to the noise power increment and the dispersion induced radio frequency signal power degradation. The maximum CNR is the peak value of the first period. For a set of specified system conditions, the P(thr) is calculated to be -21 dBm, and the optimal optical bandwidth is 0.8 nm, at which the maximum CNR is 93.3 dB by considering the noise in a 1 Hz bandwidth. The results are verified experimentally.
Integration of Bass Enhancement and Active Noise Control System in Automobile Cabin
Liang Wang
2008-01-01
Full Text Available With the advancement of digital signal processing technologies, consumers are more concerned with the quality of multimedia entertainment in automobiles. In order to meet this demand, an audio enhancement system is needed to improve bass reproduction and cancel engine noise in the cabins. This paper presents an integrated active noise control system that is based on frequency-sampling filters to track and extract the bass information from the audio signal, and a multifrequency active noise equalizer to tune the low-frequency engine harmonics to enhance the bass reproduction. In the noise cancellation mode, a maximum of 3 dB bass enhancement can be achieved with significant noise suppression, while higher bass enhancement can be achieved in the bass enhance mode. The results show that the proposed system is effective for solving both the bass audio reproduction and the noise control problems in automobile cabins.
A system for evaluating the impact of noise pollution on the population's health.
Bressane, Adriano; Mochizuki, Patricia Satie; Caram, Rosana Maria; Roveda, José Arnaldo Frutuoso
2016-05-01
The aim of this study was to develop a support system for the evaluation of noise pollution, applied to the central urban area of Rio Claro, São Paulo State, Brazil. Data were obtained from noise measurements and interviews with the population, generating the following indicators: equivalent sound level (Leq ), traffic noise index (LTNI ), and a participatory diagnosis (Dp ), integrated through a fuzzy inference system (FIS). The proposed system allowed classifying the measurement points according to the degree of impact of noise pollution on the population's health (IPS ) in the study area. Impact was considered significant in 31.4% of the measurement points and very significant in 62.9%. The FIS can be adjusted to local conditions, allowing generalization and thus also supporting noise pollution evaluation and respective environmental noise management in other geographic areas.
Effects of non-Gaussian noise on a calcium oscillation system
Wang Bing; Sun Ya-Qin; Tang Xu-Dong
2013-01-01
We investigate the effects of the non-Gaussian colored noise on a calcium oscillation system using stochastic simulation methods.It is found that the reciprocal coefficient of variance R has a maximum (Rmax) with increasing noise intensity Q.The non-Gaussian noise parameter q has an important effect on the system.For some values of q (e.g.,q =0.9,q =1.0),R has a maximum with increasing correlation time τ.Non-Gaussian noise induced spikes are more regular than Gaussian noise induced spikes when q is small and Q has large values.The R has a maximum with increasing q.Therefore,non-Gaussian noise could play more effective roles in the calcium oscillation system.
Performance analysis of UWB radio systems under cass a impulsive noise environment
JIA Lin; ZHANG Zhong-zhao
2006-01-01
The performance of UWB (Ultrawide Bandwidth) radio systems under class A impulsive noise environment is studied in this paper. First, while employing the Middleton's class A model as a model of impulsive noise, the statistical characteristics of in-phase and quadrature components of impulsive noise is investigated. It is proven that, unlike Gaussian noise, they are dependent especially due to the fact that impulsive indices are small. Next, using this above dependence, a novel UWB radio receiver designed for impulsive noise is proposed and the exact expression for theaverage BER ( Bit Error Rate) of this receiver as a function of SNR( Signal to Noise Power Ratio) and threshold value is derived. Then, the optimum threshold value is discussed and the performance of UWB radio systems with the proposed receiver designed for impulsive noise and with the conventional receiver designed for Gaussian noise under impulsive noise environment is estimated. Numerical results are compared and show that the influence of impulsiveness index and threshold value on the performance of UWB radio systems is quite large and that the performance achieved by the proposed UWB radio receiver is much superior to that of the conventional UWB radio receiver under class A impulsive noise environment.
Transport for System with Three-Value Poissonian Noise
HAN Yin-Xia; LI Jing-Hui; CHEN Shi-Gang
2004-01-01
The transport of the overdamped Brownian particles in a spatially periodic potential subject to the three value Poissonian noise in the stationary state is considered. We show that for the spatially periodic potential, no matter whether it is asymmetric, or is symmetric, flux can be induced. But the mechanism is different. The former is the common action of broken reflection symmetry and transition among three-value Poissonian noise in a cyclic way; the latter is single behavior of transition among three-value Poissonian noise in a cyclic way.
Transport for System with Three-Value Poissonian Noise
HANYin-Xia; LIJing-Hui; CHENShi-Gang
2004-01-01
The transport of the overdamped Brownian particles in a spatially periodic potential subject to the three-value Poissonian noise in the stationary state is considered. We show that for the spatially periodic potential, no matter whether it is asymmetric， or is symmetric, flux can be induced. But the mechanism is different. The former is the common action of broken reflection symmetry and transition among three-value Poissonian noise in a cyclic way; the latter is single behavior of transition among three-value Poissonian noise in a cyclic way.
Synchronization of noise-perturbed generalized Lorenz system by sliding mode control*
Kong Cui-Cui; Chen Shi-Hua
2009-01-01
Synchronization of a noise-perturbed generalized Lorenz system by using sliding mode control method is investigated in this paper. Two sliding mode control methods are proposed to synchronize the noise-perturbed generalized Lorenz system. Numerical simulations are also provided for the illustration and verification of the methods.
Low-complexity BCH codes with optimized interleavers for DQPSK systems with laser phase noise
Leong, Miu Yoong; Larsen, Knud J.; Jacobsen, Gunnar
2017-01-01
The presence of high phase noise in addition to additive white Gaussian noise in coherent optical systems affects the performance of forward error correction (FEC) schemes. In this paper, we propose a simple scheme for such systems, using block interleavers and binary Bose–Chaudhuri–Hocquenghem (...
Dependence of noise induced effects on state preparation in multiqubit systems
Tzemos, Athanasios C., E-mail: tzemos@upatras.gr; Ghikas, Demetris P.K., E-mail: ghikas@physics.upatras.gr
2013-11-08
The perturbation of multiqubit systems by an external noise can induce various effects like decoherence, stochastic resonance and anti-resonance, and noise-shielding. We investigate how the appearance of these effects on disentanglement time depends on the initial preparation of the systems. We present results for 2-, 3- and 4-qubit chains in various arrangements and observe a clear dependence on the combination of initial geometry of the state space and the placement of noise. Finally, we see that temperature can play a constructive role for the control of these noise induced effects.
Lin Ji; Yuanyuan Zhang; Xiufeng Lang; Wenxiang Hu; Qianshu Li
2009-01-01
The selective sustainment of nonlinear systems to signals is of great significance to signal transduction in living systems. We take hormone signaling as an example, and investigate the sustainment of internal and external signals. Simulation results prove that signals with "intrinsic frequency", no matter if it is noise induced or external injected, can be selectively sustained by exploiting internal and/or external noise. Both the internal and external noise can optimize the noise-induced signals, and the optimization is rather robust to the disturbance of external signals with other frequencies. These results are of significance for weak signal detection and trausduction in the presence of external signals.
Energy-Based Acoustic Measurement System for Rocket Noise Project
National Aeronautics and Space Administration — Accurate estimates of the vibroacoustic loading placed on space vehicles and payloads during launch require knowledge of the rocket noise source properties. Given...
Effect of bounded noise on chaotic motion of a triple-well potential system
Yang Xiaoli [Department of Applied Mathematics, Northwestern Polytechnic University, Xi' an 710072 (China)]. E-mail: yangxiaoli205@163.com; Xu Wei [Department of Applied Mathematics, Northwestern Polytechnic University, Xi' an 710072 (China)]. E-mail: weixu@nwpu.edu.cn; Sun Zhongkui [Department of Applied Mathematics, Northwestern Polytechnic University, Xi' an 710072 (China); Fang Tong [Department of Applied Mechanics, Northwestern Polytechnic University, Xi' an 710072 (China)
2005-07-01
The chaotic behavior of Duffing oscillator possessing both homoclinic and heteroclinic orbits and subjected to harmonic and bounded noise excitations is investigated. By means of the random Melnikov technique together with associated mean-square criterion, necessary conditions for onset of chaos resulting from homoclinic or heteroclinic bifurcation are derived semi-analytically. The results reveal that for larger noise intensity the threshold amplitude of bounded noise for onset of chaos will move upward as the noise intensity increases, which is further verified by the top Lyapunov exponents of the system. Thus the larger the noise intensity results in the less possible chaotic domain in parameter space. The effects of bounded noise on Poincare maps of the system responses are also discussed, together with the numerical simulation of the top Lyapunov exponents.
Mitigation of Noise in OFDM Based Plc System Using Filter Kernel Design
Nisha G Krishnan
2015-09-01
Full Text Available Power line communication is a technology that transforms power line in to pathway for conveyance of broadband data. It is cost less than other communication approach and for better bandwidth efficiency OFDM based PLC system is used. In real PLC environment some electrical appliances will produce noise. To mitigate this noise filter kernel design is used, so periodic impulsive noise and Gaussian noises are removed from PLC communication system by using this filter kernel design. MATLAB is used for the simulation and the result shows that filter kernel is simple and effective noise mitigation technique. Further in future, interference due to obstacles also wants to be mitigated for the better data transmission without noise.
Signal modulating noise effect in bistable stochastic resonance systems and its analog simulation
XIAO Fang-hong; YAN Gui-rong; XIE Shi-cheng
2006-01-01
The effect of signal modulating noise in bistable stochastic resonance systems was studied theoretically and experimentally. A mathematical analysis was made on the bistable stochastic resonance model with small system parameters. An analogue circuit was designed to perform the effect. The effect of signal modulating noise was shown in the analog simulation experiment. The analog experiment was conducted for two sinusoidal signals with different frequencies. The results show that there are a sinusoidal component corresponding to the input sinusoidal signal and a noise component presented as a Wiener process corresponding to the input white noise in the system output. By properly selecting system parameters, the effect of signal modulating noise can be manifested in the system output.
Adaptive Noise Cancellation Method Used for Wheel Speed Signal of Integrate ABS/ASR System
MA Yue-feng; LIU Zhao-du; QI Zhi-quan; CUI Hai-feng
2006-01-01
A novel adaptive noise cancellation method for wheel speed signal of the anti-lock braking system/anti-slip regulation(ABS/ASR) control system is proposed. Based on the spectrum distribution of vehicle's wheel speed signal got from fast Fourier transform under various conditions, the high-pass filter is used to deal with original wheel speed signals sampled to get reference noise signal and the original wheel speed signals are used as adaptive filter's desired outputs. The difference between original signals and reference noise signals is used as the error signal for the adaptive FIR filter and also used as the whole adaptive noise cancellation system's final output. This method can obtain the noise signal on-line and is easy to use for real control system,which is useful to improve the performance of integrate system ABS/ASR.
Stochastic Multi-Resonance in a Linear System Driven by Multiplicative Polynomial Dichotomous Noise
ZHANG Lu; ZHONG Su-Chuan; PENG Hao; LUO Mao-Kang
2011-01-01
We investigate stochastic resonance in a linear system subjected to multiplicative noise that is a polynomial function of colored noise. Using the stochastic averaging method, the analytical expression of the output signal-to-noise ratio (SNR) is derived. Theoretical analysis and numerical results show that the output SNR is a nonmonotonic function of both the noise intensity and the correlation rate. Moreover, the phenomoenon of stochastic multi-resonance (SMR) is found, which is not observed in conventional linear systems driven by multiplicative noise with only a linear term.%@@ We investigate stochastic resonance in a linear system subjected to multiplicative noise that is a polynomial function of colored noise.Using the stochastic averaging method,the analytical expression of the output signalto-noise ratio(SNR)is derived.Theoretical analysis and numerical results show that the output SNR is a nonmonotonic function of both the noise intensity and the correlation rate.Moreover,the phenomoenon of stochastic multi-resonance(SMR)is found,which is not observed in conventional linear systems driven by multiplicative
Park, Min-Sik; Kim, Jeonghun; Kim, Ki Jae; Lee, Jong-Won; Kim, Jung Ho; Yamauchi, Yusuke
2015-12-14
Transition metal oxides possessing two kinds of metals (denoted as AxB3-xO4, which is generally defined as a spinel structure; A, B = Co, Ni, Zn, Mn, Fe, etc.), with stoichiometric or even non-stoichiometric compositions, have recently attracted great interest in electrochemical energy storage systems (ESSs). The spinel-type transition metal oxides exhibit outstanding electrochemical activity and stability, and thus, they can play a key role in realising cost-effective and environmentally friendly ESSs. Moreover, porous nanoarchitectures can offer a large number of electrochemically active sites and, at the same time, facilitate transport of charge carriers (electrons and ions) during energy storage reactions. In the design of spinel-type transition metal oxides for energy storage applications, therefore, nanostructural engineering is one of the most essential approaches to achieving high electrochemical performance in ESSs. In this perspective, we introduce spinel-type transition metal oxides with various transition metals and present recent research advances in material design of spinel-type transition metal oxides with tunable architectures (shape, porosity, and size) and compositions on the micro- and nano-scale. Furthermore, their technological applications as electrode materials for next-generation ESSs, including metal-air batteries, lithium-ion batteries, and supercapacitors, are discussed.
Penta, Virgil; Pirvu, Cristian; Demetrescu, Ioana
2014-01-01
The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS) could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects.
Pirvu, Cristian; Demetrescu, Ioana
2014-01-01
The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS) could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects. PMID:24605336
Virgil Penta
2014-01-01
Full Text Available The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects.
Development of an Automated DNA Detection System Using an Electrochemical DNA Chip Technology
Hongo, Sadato; Okada, Jun; Hashimoto, Koji; Tsuji, Koichi; Nikaido, Masaru; Gemma, Nobuhiro
A new compact automated DNA detection system Genelyzer™ has been developed. After injecting a sample solution into a cassette with a built-in electrochemical DNA chip, processes from hybridization reaction to detection and analysis are all operated fully automatically. In order to detect a sample DNA, electrical currents from electrodes due to an oxidization reaction of electrochemically active intercalator molecules bound to hybridized DNAs are detected. The intercalator is supplied as a reagent solution by a fluid supply unit of the system. The feasibility test proved that the simultaneous typing of six single nucleotide polymorphisms (SNPs) associated with a rheumatoid arthritis (RA) was carried out within two hours and that all the results were consistent with those by conventional typing methods. It is expected that this system opens a new way to a DNA testing such as a test for infectious diseases, a personalized medicine, a food inspection, a forensic application and any other applications.
Flux for a System with Infinite Globally Coupled Oscillators Driven by Temporal-Spatial Noises
HAN Yin-Xia; LI Jing-Hui; CHEN Shi-Gang
2003-01-01
The transport of a spatially periodic system with infinite globally coupled oscillators driven by temporalspatial noises is investigated. The probability current shows that the correlation of the multiplicative noises with the space, the spatial asymmetry, and the coupling among the different oscillators are ingredients for the transport of particles. It is a new phenomenon that the correlation of the multiplicative noises with the space can induce the nonzero flux.
LI Jing-Hui
2008-01-01
A three-state Markovian noise is investigated. Its probability density and statistical properties are obtained. Escape of particles for a system with potential barrier only driven by this noise is investigated. It is shown that, in some circumstances, this noise can make the particles escape over the potential barrier; but in other circumstances, it cannot. Resonant activation phenomenon appears for the system considered by us.
Shot noise in nano-electronic systems under the perturbation of ac fields
ZHAO Hong-kang
2007-01-01
Current noise exists in circuits and electronic devices generally, and it exhibits specific features as the system reaches nanometer size. The noise in the nano-system where external ac fields are applied plays an important role, since the properties of the fields and the nano-system together govern the resulting noise. In this paper, we present the derivation of shot noise by employing the nonequilibrium Green's function technique. The more general formulas for the current correlation and noise spectral density are given. The system is composed of a central nanosystem coupled to electrodes, and the obtained noise formulas are related to the Green's functions of detailed central regime and the terminals. As an example, we have performed the numerical calculation on a system with a toroidal carbon nanotube coupled to normal metal leads. The noise and Fano factor show intimate relation with the structure of the system and ac fields. The Aharonov-Bohm-like behaviors on the shot noise spectral density and Fano factor are observed to exhibit oscillation structures with period of quantum flux.
Application of the Baseline Rotonet system to the prediction of helicopter tone noise
Golub, R. A.; Weir, D. S.; Tracy, M. B.
1986-07-01
The capabilities of the baseline Rotonet system designed to predict helicopter noise are analyzed. The modules of the system utilized for main and tail rotor geometry and blade section aerodynamic characteristics, for analyses, and for source-to-observer geometry, and atmospheric and ground effects calculations are described; a diagram of the system is provided. The Rotonet system produces axial force, tone noise, and sound pressure level information and a one third octave spectrum related to rotor tone noise and broadband noise sources. Main rotor noise predictions are compared with flight data. It is observed that both sets of data reveal increase loading on the advancing side and decrease loading on the retreating side. The tone noise and sound pressure levels for the first and second harmonics correlate well with the flight data; however, there is only fair agreement for the third harmonics of the sound pressure level. Analysis of the spectra display lower noise levels for higher altitudes and lower speeds. It is noted that the baseline Rotonet system is applicable for predicting performance and noise signatures for the lower harmonics. A phase II Rotonet system for evaluating higher harmonics is being developed.
Subotić, Miško; Šarić, Zoran; Jovičić, Slobodan T
2012-03-01
Transient otoacoustic emission (TEOAE) is a method widely used in clinical practice for assessment of hearing quality. The main problem in TEOAE detection is its much lower level than the level of environmental and biological noise. While the environmental noise level can be controlled, the biological noise can be only reduced by appropriate signal processing. This paper presents a new two-probe preprocessing TEOAE system for suppression of the biological noise by adaptive filtering. The system records biological noises in both ears and applies a specific adaptive filtering approach for suppression of biological noise in the ear canal with TEOAE. The adaptive filtering approach includes robust sign error LMS algorithm, stimuli response summation according to the derived non-linear response (DNLR) technique, subtraction of the estimated TEOAE signal and residual noise suppression. The proposed TEOAE detection system is tested by three quality measures: signal-to-noise ratio (S/N), reproducibility of TEOAE, and measurement time. The maximal TEOAE detection improvement is dependent on the coherence function between biological noise in left and right ears. The experimental results show maximal improvement of 7 dB in S/N, improvement in reproducibility near 40% and reduction in duration of TEOAE measurement of over 30%.
Effect of inertial mass on a linear system driven by dichotomous noise and a periodic signal
Li Peng; Nie Lin-Ru; Lü Xiu-Min; Zhang Qi-Bo
2011-01-01
A linear system driven by dichotomous noise and a periodic signal is investigated in the underdamped case.The exact expressions of output signal amplitude and signal-to-noise ratio (SNR) of the system are derived.By means of numerical calculation,the results indicate that (i) at some fixed noise intensities,the output signal amplitude with inertial mass exhibits the structure of a single peak and single valley,or even two peaks if the dichotomous noise is asymmetric; (ii) in the case of asymmetric dichotomous noise,the inertial mass can cause non-monotonic behaviour of the output signal amplitude with respect to noise intensity; (iii) the curve of SNR versus inertial mass displays a maximum in the case of asymmetric dichotomous noise,i.e.,a resonance-like phenomenon,while it decreases monotonically in the case of symmetric dichotomous noise; (iv) if the noise is symmetric,the inertial mass can induce stochastic resonance in the system.
Design of noise barrier inspection system for high-speed railway
Liu, Bingqian; Shao, Shuangyun; Feng, Qibo; Ma, Le; Cholryong, Kim
2016-10-01
The damage of noise barriers will highly reduce the transportation safety of the high-speed railway. In this paper, an online inspection system of noise barrier based on laser vision for the safety of high-speed railway is proposed. The inspection system, mainly consisted of a fast camera and a line laser, installed in the first carriage of the high-speed CIT(Composited Inspection Train).A Laser line was projected on the surface of the noise barriers and the images of the light line were received by the camera while the train is running at high speed. The distance between the inspection system and the noise barrier can be obtained based on laser triangulation principle. The results of field tests show that the proposed system can meet the need of high speed and high accuracy to get the contour distortion of the noise barriers.
Phase noise estimation and mitigation for DCT-based coherent optical OFDM systems.
Yang, Chuanchuan; Yang, Feng; Wang, Ziyu
2009-09-14
In this paper, as an attractive alternative to the conventional discrete Fourier transform (DFT) based orthogonal frequency division multiplexing (OFDM), discrete cosine transform (DCT) based OFDM which has certain advantages over its counterpart is studied for optical fiber communications. As is known, laser phase noise is a major impairment to the performance of coherent optical OFDM (CO-OFDM) systems. However, to our knowledge, detailed analysis of phase noise and the corresponding mitigation methods for DCT-based CO-OFDM systems have not been reported yet. To address these issues, we analyze the laser phase noise in the DCT-based CO-OFDM systems, and propose phase noise estimation and mitigation schemes. Numerical results show that the proposal is very effective in suppressing phase noise and could significantly improve the performance of DCT-based CO-OFDM systems.
Nonlinear phase noise mitigation in phase-sensitive amplified transmission systems.
Olsson, Samuel L I; Karlsson, Magnus; Andrekson, Peter A
2015-05-04
We investigate the impact of in-line amplifier noise in transmission systems amplified by two-mode phase-sensitive amplifiers (PSAs) and present the first experimental demonstration of nonlinear phase noise (NLPN) mitigation in a modulation format independent PSA-amplified transmission system. The NLPN mitigation capability is attributed to the correlated noise on the signal and idler waves at the input of the transmission span. We study a single-span system with noise loading in the transmitter but the results are expected to be applicable also in multi-span systems. The experimental investigation is supported by numerical simulations showing excellent agreement with the experiments. In addition to demonstrating NLPN mitigation we also present a record high sensitivity receiver, enabled by low-noise PSA-amplification, requiring only 4.1 photons per bit to obtain a bit error ratio (BER) of 1 × 10(-3) with 10 GBd quadrature phase-shift keying (QPSK) data.
Nakamura, M. [Hitachi, Ltd., Tokyo (Japan); Sasaki, M.; Hori, Y. [Gifu University, Gifu (Japan); Fujisawa, F. [Hachinohe Institute of Technology, Aomori (Japan); Sumida, I. [Chubu University, Nagoya (Japan)
1997-12-20
This paper proposes an active noise control system with minimized amount of calculation for periodic noise. A modified algorithm based on the filtered-x adaptive notch filter is applied on the diesel engine noise generate d in the cabin of an all-terrain vehicle. Diesel engine noise is periodic and includes some harmonic components due to engine rotation. Numerical simulation results using measured data indicated that the proposed system could be controlled by using fewer calculations compared to the conventional system. The controller was made using an eight bit microcomputer without a digital signal processor and installed in the vehicle. Results of the driving tests achieved a large noise reduction for some harmonic components, second, fourth and sixth order components. This shows that the control system is effective for noise reduction. 5 refs., 8 figs., 6 tabs.
System Noise Assessment of Blended-Wing-Body Aircraft With Open Rotor Propulsion
Guo, Yueping; Thomas, Russell H.
2015-01-01
An aircraft system noise study is presented for the Blended-Wing-Body (BWB) aircraft concept with three open rotor engines mounted on the upper surface of the airframe. It is shown that for such an aircraft, the cumulative Effective Perceived Noise Level (EPNL) is about 24 dB below the current aircraft noise regulations of Stage 4. While this makes the design acoustically viable in meeting the regulatory requirements, even with the consideration of more stringent noise regulations of a possible Stage 5 in the next decade or so, the design will likely meet stiff competitions from aircraft with turbofan engines. It is shown that the noise levels of the BWB design are held up by the inherently high noise levels of the open rotor engines and the limitation on the shielding benefit due to the practical design constraint on the engine location. Furthermore, it is shown that the BWB design has high levels of noise from the main landing gear, due to their exposure to high speed flow at the junction between the center body and outer wing. These are also the reasons why this baseline BWB design does not meet the NASA N+2 noise goal of 42 dB below Stage 4. To identify approaches that may further reduce noise, parametric studies are also presented, including variations in engine location, vertical tail and elevon variations, and airframe surface acoustic liner treatment effect. These have the potential to further reduce noise but they are only at the conceptual stage.
Auralization of NASA N+2 Aircraft Concepts from System Noise Predictions
Rizzi, Stephen A.; Burley, Casey L.; Thomas, Russel H.
2016-01-01
Auralization of aircraft flyover noise provides an auditory experience that complements integrated metrics obtained from system noise predictions. Recent efforts have focused on auralization methods development, specifically the process by which source noise information obtained from semi-empirical models, computational aeroacoustic analyses, and wind tunnel and flight test data, are used for simulated flyover noise at a receiver on the ground. The primary focus of this work, however, is to develop full vehicle auralizations in order to explore the distinguishing features of NASA's N+2 aircraft vis-à-vis current fleet reference vehicles for single-aisle and large twin-aisle classes. Some features can be seen in metric time histories associated with aircraft noise certification, e.g., tone-corrected perceived noise level used in the calculation of effective perceived noise level. Other features can be observed in sound quality metrics, e.g., loudness, sharpness, roughness, fluctuation strength and tone-to-noise ratio. A psychoacoustic annoyance model is employed to establish the relationship between sound quality metrics and noise certification metrics. Finally, the auralizations will serve as the basis for a separate psychoacoustic study aimed at assessing how well aircraft noise certification metrics predict human annoyance for these advanced vehicle concepts.
Electrochemical sensing platform based on the highly ordered mesoporous carbon-fullerene system.
Zhou, Ming; Guo, Jidong; Guo, Li-ping; Bai, Jing
2008-06-15
In this paper, we report a novel all-carbon two-dimensionally ordered nanocomposite electrode system on the basis of the consideration of host-guest chemistry, which utilizes synergistic interactions between a nanostructured matrix of ordered mesoporous carbon (OMC) and an excellent electron acceptor of nanosized fullerene (C 60) to facilitate heterogeneous electron-transfer processes. The integration of OMC-C 60 by covalent interaction, especially its electrochemical applications for electrocatalysis, has not been explored thus far. Such integration may even appear to be counterintuitive because OMC and C 60 provide opposite electrochemical benefits in terms of facilitating heterogeneous electron-transfer processes. Nevertheless, the present work demonstrates the integration of OMC and C 60 can provide a remarkable synergistic augmentation of the current. To illuminate the concept, eight kinds of inorganic and organic electroactive compounds were employed to study the electrochemical response at an OMC-C 60 modified glassy carbon (OMC-C 60/GC) electrode for the first time, which shows more favorable electron-transfer kinetics than OMC/GC, carbon nanotube modified GC, C 60/GC, and GC electrodes. Such electrocatalytic behavior at OMC-C 60/GC electrode could be attributed to the unique physicochemical properties of OMC and C 60, especially the unusual host-guest synergy of OMC-C 60, which induced a substantial decrease in the overvoltage for NADH oxidation compared with GC electrode. The ability of OMC-C 60 to promote electron transfer not only suggests a new platform for the development of dehydrogenase-based bioelectrochemical devices but also indicates a potential of OMC-C 60 to be of a wide range of sensing applications because the electrocatalysis of different electroactive compounds at the OMC-C 60/GC electrode in this work should be a good model for constructing a novel and promising electrochemical sensing platform for further electrochemical detection of
Influence of Signal and Noise on Statistical Fluctuation of Single-Mode Laser System
XU Da-Hai; CHENG Qing-Hua; CAO Li; WU Da-Jin
2006-01-01
On the basis of calculating the steady-state mean normalized intensity fluctuation of a signal-mode laser system driven by both colored pump noise with signal modulation and the quantum noise with cross-correlation between its real and imaginary parts, we analyze the influence of modulation signal, noise, and its correlation form on the statistical fluctuation of the laser system. We have found that when the amplitude of modulation signal weakens and its frequency quickens, the statistical fluctuation will reduce rapidly. The statistical fluctuation of the laser system can be restrained by reducing the intensity of pump noise and quantum noise. Moreover, with prolonging of colored cross-correlation time, the statistical fluctuation of laser system experiences a repeated changing process, that is, from decreasing to augmenting,then to decreasing, and finally to augmenting again. With the decreasing of the value of cross-correlation coefficient, the statistical fluctuation will decrease too. When the cross-correlation form between the real part and imaginary part of quantum noise is zero correlation, the statistical fluctuation of laser system has a minimum. Compared with the influence of intensity of pump noise, the influence of intensity of quantum noise on the statistical fluctuation is smaller.
Electrochemical microsensor system for cancer research on photodynamic therapy in vitro
Marzioch, J.; Kieninger, J.; Sandvik, J. A.; Pettersen, E. O.; Peng, Q.; Urban, G.
2016-10-01
An electrochemical microsensor system to investigate photodynamic therapy of cancer cells in vitro was developed and applied to monitor the cellular respiration during and after photodynamic therapy. The redox activity and therefore influence of the photodynamic drug on the sensor performance was investigated by electrochemical characterization. It was shown, that appropriate operation conditions avoid cross-sensitivity of the sensors to the drug itself. The presented system features a cell culture chamber equipped with microsensors and a laser source to photodynamically treat the cells while simultaneous monitoring of metabolic parameter in situ. Additionally, the optical setup allows to read back fluorescence signals from the photosensitizer itself or other marker molecules parallel to the microsensor readings.
Report of the EMI Testing of the Johnson Noise Thermometry System
Britton Jr., Charles L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Roberts, Michael [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2014-06-01
This report summarizes the Electromagnetic Interference (EMI) testing of the Johnson Noise Thermometry System developed at ORNL. The EMI performance is very important for Johnson Noise Thermometry because it requires accurate measurement of a very small noise signal that is amplified 10,000 times. Any interference in the form on pickup from external signal sources from such as fluorescent lighting ballasts, motors, etc. can skew the measurement. Testing is therefore very important in determining the effects of these external noise sources. Results from testing in several environments with various sources of EMI are presented here.
WANG Xin; TIAN Xu; WANG Hong-Li; OUYANG Qi; LI Hao
2004-01-01
@@ The effect of additive coloured noises, which are correlated in time, on one-dimensional travelling waves in the complex Ginzburg-Landau equation is studied by numerical simulations. We found that a small coloured noise with temporal correlation could considerably influence the stability of one-dimensional wave trains. There exists an optimal temporal correlation of noise where travelling waves are the most vulnerable. To elucidate the phenomena, we statistically calculated the convective velocities Va of the wave packets, and found that the coloured noise with an appropriate temporal correlation can decrease Va, making the system convectively more unstable.
Analysis of Beamformer Directed Single-Channel Noise Reduction System for Hearing Aid Applications
Jensen, Jesper; Pedersen, Michael Syskind
2015-01-01
We study multi-microphone noise reduction systems consisting of a beamformer and a single-channel (SC) noise reduction stage. In particular, we present and analyse a maximum likelihood (ML) method for jointly estimating the target and noise power spectral densities (psd's) entering the SC filter....... We show that the estimators are minimum variance and unbiased, and provide closed-form expressions for their mean-square error (MSE). Furthermore, we show that the MSE of the noise psd estimator is particularly simple: it is independent of target signal characteristics, frequency, and microphone...
Two-level system noise reduction for Microwave Kinetic Inductance Detectors
Noroozian, Omid; Zmuidzinas, Jonas; LeDuc, Henry G; Mazin, Benjamin A
2009-01-01
Noise performance is one of the most crucial aspects of any detector. Superconducting Microwave Kinetic Inductance Detectors (MKIDs) have an "excess" frequency noise that shows up as a small time dependent jitter of the resonance frequency characterized by the frequency noise power spectrum measured in units of Hz^2/Hz. Recent studies have shown that this noise almost certainly originates from a surface layer of two-level system (TLS) defects on the metallization or substrate. Fluctuation of these TLSs introduces noise in the resonator due to coupling of the TLS electric dipole moments to the resonator's electric field. Motivated by a semi-empirical quantitative theory of this noise mechanism, we have designed and tested new resonator geometries in which the high-field "capacitive" portion of the CPW resonator is replaced by an interdigitated capacitor (IDC) structure with 10 - 20 micron electrode spacing, as compared to the 2 micron spacing used for our more conventional CPW resonators. Measurements show tha...
Bound on range precision for shot-noise limited ladar systems.
Johnson, Steven; Cain, Stephen
2008-10-01
The precision of ladar range measurements is limited by noise. The fundamental source of noise in a laser signal is the random time between photon arrivals. This phenomenon, called shot noise, is modeled as a Poisson random process. Other noise sources in the system are also modeled as Poisson processes. Under the Poisson-noise assumption, the Cramer-Rao lower bound (CRLB) on range measurements is derived. This bound on the variance of any unbiased range estimate is greater than the CRLB derived by assuming Gaussian noise of equal variance. Finally, it is shown that, for a ladar capable of dividing a fixed amount of energy into multiple laser pulses, the range precision is maximized when all energy is transmitted in a single pulse.
Chaotic signal reconstruction with application to noise radar system
Liu, Lidong; Hu, Jinfeng; He, Zishu; Han, Chunlin; Li, Huiyong; Li, Jun
2011-12-01
Chaotic signals are potentially attractive in engineering applications, most of which require an accurate estimation of the actual chaotic signal from a noisy background. In this article, we present an improved symbolic dynamics-based method (ISDM) for accurate estimating the initial condition of chaotic signal corrupted by noise. Then, a new method, called piecewise estimation method (PEM), for chaotic signal reconstruction based on ISDM is proposed. The reconstruction performance using PEM is much better than that using the existing initial condition estimation methods. Next, PEM is applied in a noncoherent reception noise radar scheme and an improved noncoherent reception scheme is given. The simulation results show that the improved noncoherent scheme has better correlation performance and range resolution especially at low signal-to-noise ratios (SNRs).
Chaotic signal reconstruction with application to noise radar system
Liu Lidong
2011-01-01
Full Text Available Abstract Chaotic signals are potentially attractive in engineering applications, most of which require an accurate estimation of the actual chaotic signal from a noisy background. In this article, we present an improved symbolic dynamics-based method (ISDM for accurate estimating the initial condition of chaotic signal corrupted by noise. Then, a new method, called piecewise estimation method (PEM, for chaotic signal reconstruction based on ISDM is proposed. The reconstruction performance using PEM is much better than that using the existing initial condition estimation methods. Next, PEM is applied in a noncoherent reception noise radar scheme and an improved noncoherent reception scheme is given. The simulation results show that the improved noncoherent scheme has better correlation performance and range resolution especially at low signal-to-noise ratios (SNRs.
Electrochemical potential of intercalation phase: Li/V 2O 5 system
Wu, Qi-Hui
2006-12-01
In the communication, the use of photoelectron spectroscopy in evaluating the electrochemical potentials for intercalation phase (Li/V 2O 5 system) is presented. Two contributions, i.e. Fermi level shift and formation of surface dipole, are the main factors in the change of battery voltage during the Li intercalation. It was found that the formation of surface dipole plays more important role in the decrease of the battery voltage due to the adsorption of Li on the surface.
Development of Separate Sensible and Latent Cooling System Using Electrochemical Compressor
Abdelaziz, Omar [ORNL; Qu, Ming [Purdue University; Sun, Xiao-Guang [ORNL; Bahar, Bamdad [Xergy Inc.; Parmelee, William [Xergy Inc.; Fackler, Scott [Xergy Inc.; Sherrer, Richard [Xergy Inc.; Zerby, Jacob [Xergy Inc.; Chouhan, Ashish [University of Delaware; Prasad, Ajay [University of Delaware
2017-01-01
Separate sensible and latent cooling systems offer superior energy efficiency performance compared to conventional vapor compression air conditioning systems. In this paper we describe an innovative non-vapor compression system that uses electrochemical compressor (ECC) to pump hydrogen between 2-metal hydride reservoirs to provide the sensible cooling effect. The heat rejected during this process is used to regenerate the ionic liquid (IL) used for desiccant dehumidification. The overall system design is illustrated. The Xergy version 4C electrochemical compressor, while not designed as a high pressure system, develops in excess of 2 MPa (300 psia) and pressure ratios > 30. The projected base efficiency improvement of the electrochemical compressor is expected to be ~ 20% with higher efficiency when in low capacity mode due to being throttleable to lower capacity with improved efficiency. The IL was tailored to maximize the absorption/desorption rate of water vapor at moderate regeneration temperature. This IL, namely, [EMIm].OAc, is a hydrophilic IL with a working concentration range of 28.98% when operating between 25 75 C. The ECC metal hydride system is expected to show superior performance to typical vapor compression systems. As such, the combined efficiency gains from the use of ECC and separate and sensible cooling would offer significant potential savings to existing vapor compression cooling technology. A high efficiency Window Air Conditioner system is described based on this novel configuration. The system s schematic is provided. Models compared well with actual operating data obtained by running the prototype system. Finally, a model of an LiCl desiccant system in conjunction with the ECC-based metal hydride heat exchangers is provided.
Noise analysis for near field 3-D FM-CW radar imaging systems
Sheen, David M.
2015-06-19
Near field radar imaging systems are used for several applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit the performance in several ways including reduction in system sensitivity and reduction of image dynamic range. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.
Analysis of the tolerance of compressive noise radar systems to multiplicative perturbations
Shastry, Mahesh C.; Narayanan, Ram M.; Rangaswamy, Muralidhar
2014-05-01
Compressive noise radar imaging involves the inversion of a linear system using l1-based sparsity constraints. This linear system is characterized by the circulant system matrix generated by the transmit waveform. The imaging problem is solved using convex optimization. The characterization of imaging performance in the presence of additive noise and other random perturbations remains an important open problem. Computational studies designed to be generalizable suggest that uncertainties related to multiplicative noise adversely affect detection performance. Multiplicative noise occurs when the recorded transmit waveform is an inaccurate version of the actual transmitted signal. The actual transmit signal leaving the antenna is treated as the signal. If the recorded version is considered as a noisy version of this signal, then, generalizable numerical experiments show that the signal to noise ratio of the recorded signal should be greater than about 35 dB for accurate signal recovery.
GaAs Wideband Low Noise Amplifier Design for Breast Cancer Detection System
Yan, Lei; Krozer, Viktor; Delcourt, Sebastien
2009-01-01
Modern wideband systems require low-noise receivers with bandwidth approaching 10 GHz. This paper presents ultra-wideband stable low-noise amplifier MMIC with cascode and source follower buffer configuration using GaAs technology. Source degeneration, gate and shunt peaking inductors are used to ...
High phase noise tolerant pilot-tone-aided DP-QPSK optical communication systems
Zhang, Xu; Pang, Xiaodan; Deng, Lei
2012-01-01
In this paper we experimentally demonstrate a novel, high phase-noise tolerant, optical dual polarization (DP) quadrature phase-shift keying (QPSK) communication system based on pilot-tone-aided phase noise cancellation (PNC) algorithm. Vertical cavity surface emitting lasers (VCSELs...
A hybrid active/passive exhaust noise control system for locomotives
Remington, Paul J.; Knight, J. Scott; Hanna, Doug; Rowley, Craig
2005-01-01
A prototype hybrid system consisting of active and passive components for controlling far-field locomotive exhaust noise has been designed, assembled, and tested on a locomotive. The system consisted of a resistive passive silencer for controlling high-frequency broadband noise and a feedforward multiple-input, multiple-output active control system for suppressing low-frequency tonal noise. The active system used ten roof-mounted bandpass speaker enclosures with 2-12-in. speakers per enclosure as actuators, eight roof-mounted electret microphones as residual sensors, and an optical tachometer that sensed locomotive engine speed as a reference sensor. The system was installed on a passenger locomotive and tested in an operating rail yard. Details of the system are described and the near-field and far-field noise reductions are compared against the design goal. .
Electrochemical metal speciation in natural and model polyelectrolyte systems.
Hoop, van den M.A.G.T.
1994-01-01
The purpose of the research described in this thesis was to examine the applicability of electro-analytical techniques in obtaining information on the speciation of metals, i.e. their distribution over different physico-chemical forms, in aquatic systems containing charged macromolecules. In chapter
Anion-exchange membranes in electrochemical energy systems
Antanassov, Plamen B.; Dekel, Dario R.; Herring, Andrew M.; Hickner, Michael A.; Kohl, Paul A.; Kucernak, Anthony R.; Mustain, William E.; Nijmeijer, Kitty; Scott, Keith; Varcoe, John R.; Xu, Tongwen; Zhuang, Lin
2014-01-01
This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current stat
Electrochemical metal speciation in natural and model polyelectrolyte systems
Hoop, van den M.A.G.T.
1994-01-01
The purpose of the research described in this thesis was to examine the applicability of electro-analytical techniques in obtaining information on the speciation of metals, i.e. their distribution over different physico-chemical forms, in aquatic systems containing charged macromolecules.
Noise in a Calorimeter Readout System Using Periodic Sampling
Innes, Walter R.; /SLAC
2009-02-26
Fourier transform analysis of the calorimeter noise problem gives quantitative results on (a) the time-height correlation, (b) the effect of background on optimal shaping and on the ENC, (c) sampling frequency requirements, and (d) the relation between sampling frequency and the required quantization error.
Attractors for stochastic lattice dynamical systems with a multiplicative noise
Tomás CARABALLO; Kening LU
2008-01-01
In this paper,we consider a stochastic lattice differential equation with diffusive nearest neighbor interaction,a dissipative nonlinear reaction term,and multiplicative white noise at each node.We prove the existence of a compact global random attractor which,pulled back,attracts tempered random bounded sets.
Thomas, Russell H.; Burley, Casey L.; Guo, Yueping
2016-01-01
Aircraft system noise predictions have been performed for NASA modeled hybrid wing body aircraft advanced concepts with 2025 entry-into-service technology assumptions. The system noise predictions developed over a period from 2009 to 2016 as a result of improved modeling of the aircraft concepts, design changes, technology development, flight path modeling, and the use of extensive integrated system level experimental data. In addition, the system noise prediction models and process have been improved in many ways. An additional process is developed here for quantifying the uncertainty with a 95% confidence level. This uncertainty applies only to the aircraft system noise prediction process. For three points in time during this period, the vehicle designs, technologies, and noise prediction process are documented. For each of the three predictions, and with the information available at each of those points in time, the uncertainty is quantified using the direct Monte Carlo method with 10,000 simulations. For the prediction of cumulative noise of an advanced aircraft at the conceptual level of design, the total uncertainty band has been reduced from 12.2 to 9.6 EPNL dB. A value of 3.6 EPNL dB is proposed as the lower limit of uncertainty possible for the cumulative system noise prediction of an advanced aircraft concept.
New RLS Wiener Smoother for Colored Observation Noise in Linear Discrete-time Stochastic Systems
Seiichi Nakamori
2013-12-01
Full Text Available In the estimation problems, rather than the white observation noise, there are cases where the observation noise is modeled by the colored noise process. In the observation equation, the observed value y(k is given as a sum of the signal z(k=Hx(k and the colored observation noise v_c(k. In this paper, the observation equation is converted to the new observation equation for the white observation noise. In accordance with the observation equation for the white observation noise, this paper proposes new RLS Wiener estimation algorithms for the fixed-point smoothing and filtering estimates in linear discrete-time wide-sense stationary stochastic systems. The RLS Wiener estimators require the following information: (a the system matrix for the state vector x(k; (b the observation matrix H; (c the variance of the state vector x(k; (d the system matrix for the colored observation noise v_c(k; (e the variance of the colored observation noise.
Wavelet Adaptive Algorithm and Its Application to MRE Noise Control System
Zhang Yulin
2015-01-01
Full Text Available To address the limitation of conventional adaptive algorithm used for active noise control (ANC system, this paper proposed and studied two adaptive algorithms based on Wavelet. The twos are applied to a noise control system including magnetorheological elastomers (MRE, which is a smart viscoelastic material characterized by a complex modulus dependent on vibration frequency and controllable by external magnetic fields. Simulation results reveal that the Decomposition LMS algorithm (D-LMS and Decomposition and Reconstruction LMS algorithm (DR-LMS based on Wavelet can significantly improve the noise reduction performance of MRE control system compared with traditional LMS algorithm.
Development of a proton-exchange membrane electrochemical reclaimed water post-treatment system
Kaba, Lamine; Verostko, Charles E.; Hitchens, G. D.; Murphy, Oliver J.
1991-01-01
A single-cell electrochemical reactor that utilizes a proton exchange membrane (PEM) as a solid electrolyte is being investigated for posttreatment of reclaimed waste waters with low or negligible electrolyte content. Posttreatment is a final 'polishing' of reclaimed waste waters prior to reuse, and involves removing organic impurities at levels as high as 100 ppm to below 500 ppb total organic carbon (TOC) content to provide disinfection. The system does not utilize or produce either expendable hardware components or chemicals and has no moving parts. Test data and kinetic analysis are presented. The feasibility and application for water reclamation processes in controlled ecological environments (e.g., lunar/Mars habitats) are also presented. Test results show that the electrochemical single cell reactor provides effective posttreatment.
Danial, Wan Hazman, E-mail: hazmandanial@gmail.com; Majid, Zaiton Abdul, E-mail: zaiton@kimia.fs.utm.my; Aziz, Madzlan [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor (Malaysia); Chutia, Arunabhiram [Institute of Fluid Sciences, Tohoku University, Sendai 980-8577 (Japan); Sahnoun, Riadh [Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor (Malaysia)
2015-07-22
The present work reports the synthesis and characterization of graphene via electrochemical exfoliation of graphite rod using two-electrode system assisted by Sodium Dodecyl Sulphate (SDS) as a surfactant. The electrochemical process was carried out with sequence of intercalation of SDS onto the graphite anode followed by exfoliation of the SDS-intercalated graphite electrode when the anode was treated as cathode. The effect of intercalation potential from 5 V to 9 V and concentration of the SDS surfactant of 0.1 M and 0.01 M were investigated. UV-vis Spectroscopic analysis indicated an increase in the graphene production with higher intercalation potential. Transmission Electron Microscopy (TEM) analysis showed a well-ordered hexagonal lattice of graphene image and indicated an angle of 60° between two zigzag directions within the honeycomb crystal lattice. Raman spectroscopy analysis shows the graphitic information effects after the exfoliation process.
Lee, Ying-Hui; Lee, Ying-Feng; Hu, Chi-Chang [Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu (Taiwan); Chang, Kuo-Hsin [Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu (Taiwan); Department of Chemical Engineering, National Chung Cheng University, Chia-Yi (Taiwan)
2011-01-15
This study proposes a simple method for synthesizing carbon nanosheets doped with nitrogen through carbonization of collagen. Collagen, the most abundant protein in mammals, was cross-linked with paraformaldehyde and subsequently heated in vacuum at 800 C to obtain N-doped carbon nanosheets with a high specific surface area of 695 m{sup 2} g{sup -1}. With the contribution of N-doped structures, the carbon nanosheets show ideal capacitive behavior with 80% capacitance retention in 0.5 M H{sub 2}SO{sub 4} at 1000 mV s{sup -1}. In comparison with a commercial electrocatalyst, 20% Pt on Vulcan XC-72, carbon nanosheets display a positive shift in the onset potential and superior electrocatalytic activity toward the oxygen reduction reaction (ORR). The above excellent electrochemical performances render the N-doped carbon nanosheets a promising material for electrochemical energy storage/conversion systems. (author)
Noise-correlation-time-mediated localization in random nonlinear dynamical systems
Cabrera, J L; De la Rubia, F J; Cabrera, Juan L.
1999-01-01
We investigate the behavior of the residence times density function for different nonlinear dynamical systems with limit cycle behavior and perturbed parametrically with a colored noise. We present evidence that underlying the stochastic resonancelike behavior with the noise correlation time, there is an effect of optimal localization of the system trajectories in the phase space. This phenomenon is observed in systems with different nonlinearities, suggesting a degree of universality.
Dichotomous-noise-induced pattern formation in a reaction-diffusion system
Das, Debojyoti; Ray, Deb Shankar
2013-06-01
We consider a generic reaction-diffusion system in which one of the parameters is subjected to dichotomous noise by controlling the flow of one of the reacting species in a continuous-flow-stirred-tank reactor (CSTR) -membrane reactor. The linear stability analysis in an extended phase space is carried out by invoking Furutzu-Novikov procedure for exponentially correlated multiplicative noise to derive the instability condition in the plane of the noise parameters (correlation time and strength of the noise). We demonstrate that depending on the correlation time an optimal strength of noise governs the self-organization. Our theoretical analysis is corroborated by numerical simulations on pattern formation in a chlorine-dioxide-iodine-malonic acid reaction-diffusion system.
Jørgensen, Bo Foged; Mikkelsen, Benny; Mahon, Cathal J.
1992-01-01
performance. Two types of optical image rejection receivers are investigated: a novel, all-optical configuration and the conventional, microwave-based configuration. The analysis shows that local oscillator-spontaneous emission beat noise (LO-SP), signal-spontaneous emission beat noise (S-SP), and spontaneous......A detailed theoretical analysis of optical amplifier noise in coherent optical communication systems with heterodyne receivers is presented. The analysis quantifies in particular how optical image rejection receiver configurations reduce the influence of optical amplifier noise on system......-spontaneous beat noise (SP-SP) can all be reduced by 3 dB, thereby doubling the dynamic range of the optical amplifier. A 2.5-dB improvement in dynamic range has been demonstrated experimentally with the all-optical image rejection configuration. The implications of the increased dynamic range thus obtained...
Oxalic acid based chemical systems for electrochemical mechanical planarization of copper
Lowalekar, Viral Pradeep
In an ECMP process, a wafer is anodically baised during polishing. The electrical potential is the driving force to oxidize copper metal to ions. Copper ions then react with chemistry in the electrolyte to go in solution or form a passivation layer on the surface. The passivation layer is removed by a very low downforce (0.5--1 psi), causing copper to electrochemically dissolve in solution. Passive film formation during copper ECMP is key to the success of this process, since passivation reduces dissolution in the recessed areas, while elevations on the copper surface in direct contact with the ECMP pad are electrochemically planarized. If no passive film forms, then copper removal will be conformal from the elevated and recessed areas, and planarity will be lost. Chemical formulations for the electrochemical mechanical planarization (ECMP) of copper must contain constituents that are stable at anodic potentials. A key component of the formulation is a corrosion inhibitor, which is required to protect low lying areas while higher areas are selectively removed. Organic compounds, which adsorb on copper at low overpotentials and form a film by oxidation at higher overpotentials, may be particularly useful for ECMP. The main goal of the research reported in this dissertation is to understand and develop oxalic acid-based chemical systems suitable for ECMP of copper through electrochemical and surface investigations. Special attention was paid to the development of an inhibitor, which can function under applied potential conditions. Physical methods such as profilometry and four point probe were used to obtain copper removal rates. An organic compound, thiosalicylic acid (TSA), was identified and tested as a potential corrosion inhibitor for copper. TSA offers better protection than the conventionally used benzotriazole (BTA) by oxidizing at high anodic potentials to form a passive film on the copper surface. The passive film formed on the copper surface by addition of
A review and update of the NASA aircraft noise prediction program propeller analysis system
Golub, Robert A.; Nguyen, L. Cathy
1989-01-01
The National Aeronautics and Space Administration (NASA) Aircraft Noise Prediction Program (ANOPP) Propeller Analysis System (PAS) is a set of computational modules for predicting the aerodynamics, performance, and noise of propellers. The ANOPP PAS has the capability to predict noise levels for propeller aircraft certification and produce parametric scaling laws for the adjustment of measured data to reference conditions. A technical overview of the prediction techniques incorporated into the system is presented. The prediction system has been applied to predict the noise signature of a variety of propeller configurations including the effects of propeller angle of attack. A summary of these validation studies is discussed with emphasis being placed on the wind tunnel and flight test programs sponsored by the Federal Aviation Administration (FAA) for the Piper Cherokee Lance aircraft. A number of modifications and improvements have been made to the system and both DEC VAX and IBM-PC versions of the system have been added to the original CDC NOS version.
Pena-Ballesteros, D.; Rodriguez-Vanegas, N.; Anteliz, C.; Sarmiento Klapper, H.
2011-07-01
The concentration of chloride ions and the partial pressure of CO{sub 2} play an important role in the degradation of low-carbon steels used for the construction of pipelines in oil and gas industry. In order to evaluate the susceptibility of carbon steel API 5L X42 to pitting corrosion electrochemical noise and linear polarization resistance measurements were carried out in aqueous solutions containing chloride ions and CO{sub 2}. The concentration of chloride ions was varied between, 10000 and 18000 ppm, and the CO{sub 2} partial pressure between 10 psi and 18 psi. Experimental results pointed out that the formation of protective layer, consisting mainly of FeCO{sub 3}, depends on the partial pressure of CO{sub 2} in the system. Nevertheless, the stability of this layer was considerably affected by increasing the concentration of chloride ions causing that localized corrosion has taken place in some areas of the surface of API 5L X42, which were detected by electrochemical noise technique. (Author) 10 refs.
Analysis of weak signal detection based on tri-stable system under Levy noise
Li-Fang, He; Ying-Ying, Cui; Tian-Qi, Zhang; Gang, Zhang; Ying, Song
2016-06-01
Stochastic resonance system is an effective method to extract weak signal. However, system output is directly influenced by system parameters. Aiming at this, the Levy noise is combined with a tri-stable stochastic resonance system. The average signal-to-noise ratio gain is regarded as an index to measure the stochastic resonance phenomenon. The characteristics of tri-stable stochastic resonance under Levy noise is analyzed in depth. First, the method of generating Levy noise, the effect of tri-stable system parameters on the potential function and corresponding potential force are presented in detail. Then, the effects of tri-stable system parameters w, a, b, and Levy noise intensity amplification factor D on the resonant output can be explored with different Levy noises. Finally, the tri-stable stochastic resonance system is applied to the bearing fault detection. Simulation results show that the stochastic resonance phenomenon can be induced by tuning the system parameters w, a, and b under different distributions of Levy noise, then the weak signal can be detected. The parameter intervals which can induce stochastic resonances are approximately equal. Moreover, by adjusting the intensity amplification factor D of Levy noise, the stochastic resonances can happen similarly. In bearing fault detection, the detection effect of the tri-stable stochastic resonance system is superior to the bistable stochastic resonance system. Project supported by the National Natural Science Foundation of China (Grant No. 61371164), the Chongqing Municipal Distinguished Youth Foundation, China (Grant No. CSTC2011jjjq40002), and the Research Project of Chongqing Municipal Educational Commission, China (Grant No. KJ130524).
Probing individual quantum dots: noise in self-assembled systems.
Vicaro, K O; Gutiérrez, H R; Seabra, A C; Schulz, P A; Cotta, M A
2009-11-01
In this work we explore the noise characteristics in lithographically-defined two terminal devices containing self-assembled InAs/InP quantum dots. The experimental ensemble of InAs dots show random telegraph noise (RTN) with tuneable relative amplitude-up to 150%-in well defined temperature and source-drain applied voltage ranges. Our numerical simulation indicates that the RTN signature correlates with a very low number of quantum dots acting as effective charge storage centres in the structure for a given applied voltage. The modulation in relative amplitude variation can thus be associated to the altered electrostatic potential profile around such centres and enhanced carrier scattering provided by a charged dot.
Experiments on Exhaust Noise of Tightly Integrated Propulsion Systems
Bridges, James E.; Brown, Clifford A.; Bozak, Richard F.
2014-01-01
A wide-ranging series of tests have been completed that seek to map the effects of installation, including jet by jet interaction effects, on exhaust noise from various nozzles in forward flight. The primary data was far-field acoustic spectral directivity. The goals of the test series were (i) to generate enough data for empirical models of the different effects, and (ii) to provide data for advanced computational noise predictions methods applied to simplified yet realistic configurations. Data is presented that demonstrate several checks on data quality and that provide an overview of trends observed to date. Among the findings presented here: (i) Data was repeatable between jet rigs for single nozzles with and without surfaces to within +/- 0.5 dB. (ii) The presence of a second jet caused a strong reduction of the summed noise in the plane of the two plumes and an increase over the expected source doubling in most other azimuthal planes. (iii) The impact of the second jet was reduced when the jets were unheated. (iv) The impact of adding a second isolated rectangular jet was relatively independent of the nozzle aspect ratio up to aspect ratio 8:1. (v) Forward flight had similar impact on a high aspect ratio (8:1) jet as on an axisymmetric jet, except at the peak noise angle where the impact was less. (vi) The effect of adding a second round jet to a tightly integrated nozzle where the nozzle lip was less than a diameter from the surface was very dependent upon the length of the surface downstream of the nozzle. (vii) When the nozzles were rectangular and tightly integrated with the airframe surface the impact of a second jet was very dependent upon how close together the two jets were. This paper serves as an overview of the test; other papers presented in the same conference will give more detailed analysis of the results.
Khan, Muhammad Jibran; Mahmood, Waqas
2015-12-01
The performance of the human hand gesture recognition systems depends on the quality of the images presented to the system. Since these systems work in real time environment the images may be corrupted by some environmental noise. By removing the noise the performance of the system can be enhanced. So far different noise removal methods have been presented in many researches to eliminate the noise but all have its own limitations. We have presented a region finding method to deal with the environmental noise that gives better results and enhances the performance of the human hand gesture recognition systems so that the recognition rate of the system can be improved.
Hybrid Active/Passive Jet Engine Noise Suppression System
Parente, C. A.; Arcas, N.; Walker, B. E.; Hersh, A. S.; Rice, E. J.
1999-01-01
A novel adaptive segmented liner concept has been developed that employs active control elements to modify the in-duct sound field to enhance the tone-suppressing performance of passive liner elements. This could potentially allow engine designs that inherently produce more tone noise but less broadband noise, or could allow passive liner designs to more optimally address high frequency broadband noise. A proof-of-concept validation program was undertaken, consisting of the development of an adaptive segmented liner that would maximize attenuation of two radial modes in a circular or annular duct. The liner consisted of a leading active segment with dual annuli of axially spaced active Helmholtz resonators, followed by an optimized passive liner and then an array of sensing microphones. Three successively complex versions of the adaptive liner were constructed and their performances tested relative to the performance of optimized uniform passive and segmented passive liners. The salient results of the tests were: The adaptive segmented liner performed well in a high flow speed model fan inlet environment, was successfully scaled to a high sound frequency and successfully attenuated three radial modes using sensor and active resonator arrays that were designed for a two mode, lower frequency environment.
Response of Duffing Rayleigh system with fractional derivative under Gaussian white noise excitation
张冉冉; 徐伟; 杨贵东; 韩群
2015-01-01
In this paper, we consider the response analysis of Duffing–Rayleigh system with fractional derivative under Gaussian white noise excitation. A stochastic averaging procedure for this system is developed by using the generalized harmonic functions. First, the system state is approximated by a diffusive Markov process. Then, the stationary probability densities are derived from the averaged Itˆo stochastic differential equation of the system. The accuracy of the analytical results is validated by those results from the Monte Carlo simulation of original system. Moreover, the effects of different system parameters and noise intensity on the response of the system are discussed as well.
S. Peng
2015-04-01
Full Text Available Nonlinear companding transform is an efficient method to reduce the high peak-to-average power ratio (PAPR of multicarrier transmission systems. However, the introduced companding noise greatly degrades the bit-error-rate (BER performance of the companded multicarrier systems. In this paper, a simplified but effective scheme of estimation and cancellation of companding noise for the companded multicarrier transmission system is proposed. By expressing the companded signals as the summation of original signals added with a companding noise component, and subtracting this estimated companding noise from the received signals, the BER performance of the overall system can be significantly improved. Simulation results well confirm the great advantages of the proposed scheme over other conventional decompanding or no decompanding schemes under various situations.
Microwave Oscillator Phase Noise Requirement for TD-SCDMA Wireless Communication Systems
Song-Bai HE; Xiao-Huan Yan; Jing-Fu Bao
2007-01-01
In time division synchronous code division multiple access (TD-SCDMA) wireless communication systems, QPSK or 8PSK has been employed to support high data rate services and high efficiency in available bandwidth. The performance of such systems is affected by the phase noise of the microwave local oscillator. The phase noise model of synthesizer and the RF transceiver model for the phase noise effect are proposed for applications of TD-SCDMA systems. The relationship between the power spectral density (PSD) and root mean square (RMS) phase error is given. Then, the error vector magnitude (EVM) performance is analytically evaluated by using the single side band (SSB) phase noise. Theoretical results show agreement with those obtained by measurement data and therefore can be used to derive the TD-SCDMA system performance.
Lee, R. E.
2017-01-01
Electrochemical and crevice corrosion laboratory test results are presented for three noble metal candidates with possible application on the Universal Waste Management System (UWMS) in support of the Environmental Control and Life Support System (ECLSS) aboard the International Space Station (ISS). The three metal candidates, which included Inconel 625, Hastelloy C276 and Titanium 6Al-4V, were evaluated in two solutions representative of the acidic pretreatment formulations utilized during processing of waste liquids within the ECLSS. Final test results and data analysis indicated that the passive layer on all three metals provides excellent corrosion protection in both solutions under standard test conditions.
Kim, Hyeonsu; Seo, Jongpil; Ahn, Jongmin; Chung, Jaehak
2017-07-01
We propose a mitigation scheme for snapping shrimp noise when it corrupts an orthogonal frequency division multiplexing (OFDM) signal in underwater acoustic communication systems. The OFDM signal distorted by the snapping shrimp noise is filtered by a band-stop filter. The snapping shrimp noises in the filtered signal are detected by a detector with a constant false alarm rate whose threshold is derived theoretically from the statistics of the background noise. The detected signals are reconstructed by a simple reconstruction method. The proposed scheme has a higher detection capability and a lower mean square error of the channel estimation for simulated data and a lower bit error rate for practical ocean OFDM data collected in northern East China Sea than the conventional noise-mitigating methods.
Stochastic resonance in parabolic-bistable potential system with an additive colour noise
梁贵云
2003-01-01
We propose a new model (parabolic bistable system) with a colour noise source. In the presence of periodic input signal, we investigate the output signal to-noise ratio and the power spectral density of output signal, in which the self-correlation time may be an arbitrary value with no restriction. We find that the curves of signal-to-noise ratio versus the noise intensity D exhibits a bell-shape behaviour. The peak height increases with the increasing value of amplitude A0 of the input signal. However, the position of peak does not shift. Moreover, the signal-to-noise ratio is insensitive to the modulation frequency Ω, which completely differs from result of Ref.[6]. The power spectral density also has similar behaviour.
Stochastic resonance in parabolic—bistable potential system with an additive colour noise
LiangGui-Yun
2003-01-01
We propose a new model (parabolic bistable system) with a colour noise source. In the presence of periodic input signal, we investigate the output signal to noise ratio and the power spectral density of output signal, in which the self-correlation time may be an arbitrary value with no restriction. We find that the curves of signal-to-noise ratio versus the noise intensity D exhibits a bell-shape behaviour. The peak height increases with the increasing value of amplitude A0 of the input signal. However, the position of peak does not shift. Moreover, the signal-to-noise ratio is insensitive to the modulation frequency Ω，which completely differs from result of Ref [6]. The power spectral density also has similar behaviour.
Estimation of noise parameters in dynamical system identification with Kalman filters.
Kwasniok, Frank
2012-09-01
A method is proposed for determining dynamical and observational noise parameters in state and parameter identification from time series using Kalman filters. The noise covariances are estimated in a secondary optimization by maximizing the predictive likelihood of the data. The approach is based on internal consistency; for the correct noise parameters, the uncertainty projected by the Kalman filter matches the actual predictive uncertainty. The method is able to disentangle dynamical and observational noise. The algorithm is demonstrated for the linear, extended, and unscented Kalman filters using an Ornstein-Uhlenbeck process, the noise-driven Lorenz system, and van der Pol oscillator as well as a paleoclimatic ice-core record as examples. The approach is also applicable to the ensemble Kalman filter and can be readily extended to non-Gaussian estimation frameworks such as Gaussian-sum filters and particle filters.
A new VOX technique for reducing noise in voice communication systems. [voice operated keying
Morris, C. F.; Morgan, W. C.; Shack, P. E.
1974-01-01
A VOX technique for reducing noise in voice communication systems is described which is based on the separation of voice signals into contiguous frequency-band components with the aid of an adaptive VOX in each band. It is shown that this processing scheme can effectively reduce both wideband and narrowband quasi-periodic noise since the threshold levels readjust themselves to suppress noise that exceeds speech components in each band. Results are reported for tests of the adaptive VOX, and it is noted that improvements can still be made in such areas as the elimination of noise pulses, phoneme reproduction at high-noise levels, and the elimination of distortion introduced by phase delay.
Reducing coherent noise in interference systems using the phase modulation technique.
Cui, Ji-Wen; Tao, Zhang; Liu, Zhao-Bo; Tan, Jiu-Bin
2015-08-20
The phase modulation technique is adopted to reduce the coherent noise that arises from spurious interference. By choosing an appropriate driving signal, the method can reduce the coherent function of coherent noise to a great degree while keeping the coherent function of a coherent signal nearly unchanged. Simulation results show that for the grating interferometer, the phase error caused by coherent noise is reduced by 81.53% on average. For the Twyman interferometer, the fringe quality and contrast deteriorated by coherent noise are significantly improved. Furthermore, an experiment is set up in the phase-modulated Twyman interferometer to verify the feasibility of the principle. It is concluded that the method is effective to reduce the coherent noise in interference systems.
Control design for discrete-time state-multiplicative noise stochastic systems
Krokavec, Dušan; Filasová, Anna
2015-11-01
Design conditions for existence of the H∞ linear state feedback control for discretetime stochastic systems with state-multiplicative noise and polytopic uncertainties are presented in the paper. Using an enhanced form of the bounded real lemma for discrete-time stochastic systems with state-multiplicative noise, the LMI-based procedure is provided for computation of the gains of linear, as well as nonlinear, state control law. The approach is illustrated on an example demonstrating the validity of the proposed method.
Novel BCH Code Design for Mitigation of Phase Noise Induced Cycle Slips in DQPSK Systems
Leong, M. Y.; Larsen, Knud J.; Jacobsen, G.
2014-01-01
We show that by proper code design, phase noise induced cycle slips causing an error floor can be mitigated for 28 Gbau d DQPSK systems. Performance of BCH codes are investigated in terms of required overhead......We show that by proper code design, phase noise induced cycle slips causing an error floor can be mitigated for 28 Gbau d DQPSK systems. Performance of BCH codes are investigated in terms of required overhead...
ClassTalk system for predicting and auralizing speech in noise with reverberation in classrooms
Hodgson, Murray; Graves, Daniel
2005-04-01
This paper discusses and demonstrates the ClassTalk system for predicting, visualizing and auralizing speech in noise with reverberation in classrooms. The classroom can contain a speech-reinforcement system (SRS). Male or female speech sources, SRS loudspeakers and overhead, slide or digital projectors, or ventilation-noise sources, can have four output levels. Empirical models are used to predict speech and noise levels, and Early Decay Times, from which Speech Transmission Index (STI) and Speech Intelligibility (SI) are calculated. ClassTalk visualizes the floor-plan, speech- and noise-source positions, and the receiver position. The user can walk through the room at will. In real time five quantities, background-noise level, speech level, signal-to-noise difference, STI and SI, are displayed along with occupied and unoccupied reverberation times. The sound module auralizes male or female speech mixed with the relevant noise signals, with predicted, frequency-varying reverberation superimposed using MaxxVerb. Technical issues related to the development of the sound module are discussed. The potential of the systems auralization module for demonstrating the effects of the acoustical environment and its control on speech is discussed and demonstrated.
Output feedback control for a class of nonlinear systems with actuator degradation and sensor noise.
Ai, Weiqing; Lu, Zhenli; Li, Bin; Fei, Shumin
2016-11-01
This paper investigates the output feedback control problem of a class of nonlinear systems with sensor noise and actuator degradation. Firstly, by using the descriptor observer approach, the origin system is transformed into a descriptor system. On the basis of the descriptor system, a novel Proportional Derivative (PD) observer is developed to asymptotically estimate sensor noise and system state simultaneously. Then, by designing an adaptive law to estimate the effectiveness of actuator, an adaptive observer-based controller is constructed to ensure that system state can be regulated to the origin asymptotically. Finally, the design scheme is applied to address a flexible joint robot link problem.
Shuo Zhang,Yan Zhao,Min Li,; Jianhui Zhao
2015-01-01
The global y optimal recursive filtering problem is stu-died for a class of systems with random parameter matrices, stochastic nonlinearities, correlated noises and missing measure-ments. The stochastic nonlinearities are presented in the system model to reflect multiplicative random disturbances, and the addi-tive noises, process noise and measurement noise, are assumed to be one-step autocorrelated as wel as two-step cross-correlated. A series of random variables is introduced as the missing rates governing the intermittent measurement losses caused by un-favorable network conditions. The aim of the addressed filtering problem is to design an optimal recursive filter for the uncertain systems based on an innovation approach such that the filtering error is global y minimized at each sampling time. A numerical simulation example is provided to il ustrate the effectiveness and applicability of the proposed algorithm.
Guo, Xiaoling; Wang, Qian; Li, Jinlian; Cui, Jiwen; Zhou, Shi; Hao, Sue; Wu, Dongmei
2015-02-15
Developing a reliable and cost-effective miniaturized electroanalysis tool is of vital importance for cell electrochemical analysis. In this work, a novel mini-electrochemical system has been constructed for trace detection of cell samples. The mini-electrochemical system was constructed by integrating a pencil graphite modified by threonine (PT/PGE) as working electrode, an Ag/AgCl (Sat'd) as reference electrode, platinum wire as counter electrode and a micropipet tip as electrochemical cell. The mini-electrochemical system not only saved dramatically usage of samples from 500 μL in traditional electrochemical system to 10 μL, but also possessed an adjustable active surface area by changing the length of PT/PGE immersed into the cell suspension from 3mm to 15 mm, and the linear equation was ipa = 2.25 l-2.64 (R(2) = 0.990). The system was successfully used in detection of MCF-7 cells, and a nonlinear exponent relationship between peak current and the cell number range from 3.0 × l0(3) to 7.0 × l0(6) cells mL(-1) was established firstly with the index equation ipa = 59.557 e (-C/1.709)-71.486 (R(2) = 0.954). Finally, the system was used for evaluating the sensitivity of cyclophosphamide on MCF-7 cell, and the result was corresponded well with that of MTT assay. The proposed system is sufficiently simple, cheap and easy operated, and could be applied in electrochemical detection of other biological samples.
Influence of perturbative phase noise on active coherent polarization beam combining system.
Ma, Pengfei; Zhou, Pu; Wang, Xiaolin; Ma, Yanxing; Su, Rongtao; Liu, Zejin
2013-12-02
In this manuscript, the influence of perturbative phase noise on active coherent polarization beam combining (CPBC) system is studied theoretically and experimentally. By employing a photo-detector to obtain phase error signal for feedback loop, actively coherent polarization beam combining of two 20 W-level single mode polarization-maintained (PM) fiber amplifiers are demonstrated with more than 94% combining efficiency. Then the influence of perturbative phase noise on active CPBC system is illustrated by incorporating a simulated phase noise signal in one of the two amplifiers. Experimental results show that the combining efficiency of the CPBC system is susceptible to the frequency or amplitude of the perturbative phase noise. In order to ensure the combining efficiency of the unit of CPBC system higher than 90%, the competence of our active phase control module for high power operation is discussed, which suggests that it could be worked at 100s W power level. The relationship between residual phase noise of the active controller and the normalized voltage signal of the photo-detector is developed and validated experimentally. Experimental results correspond exactly with the theoretically analyzed combining efficiency. Our method offers a useful approach to estimate the influence of phase noise on CPBC system.
Cascaded systems analysis of noise reduction algorithms in dual-energy imaging.
Richard, Samuel; Siewerdsen, Jeffrey H
2008-02-01
An important aspect of dual-energy (DE) x-ray image decomposition is the incorporation of noise reduction techniques to mitigate the amplification of quantum noise. This article extends cascaded systems analysis of imaging performance to DE imaging systems incorporating linear noise reduction algorithms. A general analytical formulation of linear DE decomposition is derived, with weighted log subtraction and several previously reported noise reduction algorithms emerging as special cases. The DE image noise-power spectrum (NPS) and modulation transfer function (MTF) demonstrate that noise reduction algorithms impart significant, nontrivial effects on the spatial-frequency-dependent transfer characteristics which do not cancel out of the noise-equivalent quanta (NEQ). Theoretical predictions were validated in comparison to the measured NPS and MTF. The resulting NEQ was integrated with spatial-frequency-dependent task functions to yield the detectability index, d', for evaluation of DE imaging performance using different decomposition algorithms. For a 3 mm lung nodule detection task, the detectability index varied from d' 2.5 (i.e., nodule clearly visible) for "anti-correlated noise reduction" (ACNR) or "simple-smoothing of the high-energy image" (SSH) algorithms applied to soft-tissue or bone-only decompositions, respectively. Optimal dose allocation (A*, the fraction of total dose delivered in the low-energy projection) was also found to depend on the choice of noise reduction technique. At fixed total dose, multi-function optimization suggested a significant increase in optimal dose allocation from A* = 0.32 for conventional log subtraction to A* = 0.79 for ACNR and SSH in soft-tissue and bone-only decompositions, respectively. Cascaded systems analysis extended to the general formulation of DE image decomposition provided an objective means of investigating DE imaging performance across a broad range of acquisition and decomposition algorithms in a manner that
Noise Source Identification of Small Fan-BLDC Motor System for Refrigerators
Yong-Han Kim
2006-01-01
Full Text Available Noise levels in household appliances are increasingly attracting attention from manufacturers and customers. Legislation is becoming more severe on acceptable noise levels and low noise is a major marketing point for many products. The latest trend in the refrigerator manufacturing industry is to use brushless DC (BLDC motors instead of induction motors in order to reduce energy consumption and noise radiation. However, cogging torque from BLDC motor is an undesirable effect that prevents the smooth rotation of the rotor and results in noise. This paper presents a practical approach for identifying the source of excessive noise in the small fan-motor system for household refrigerators. The source is presumed to a mechanical resonance excited by torque ripple of the BLDC motor. By using finite element analysis, natural frequencies and mode shapes of the rotating part of the system are obtained and they are compared with experimental mode shapes obtained by electronic torsional excitation test which uses BLDC motor itself as an exciter. Two experimental validations are carried out to confirm the reduction of excessive noise.
Overpressure and noise due to multiple airbag systems in a passenger car
Hickling, Robert; Henning, Peter J.; Newton, Gary, Jr.
2002-11-01
Multiple airbag systems in passenger cars can generate overpressure and noise that may be hazardous to human hearing. Overpressure is compression of the air inside a closed compartment caused by deployment of the bags. Noise results from the action of the gas inflating the bags. SAE J247 provides a standard for measuring the combination of overpressure and noise in a passenger compartment. A special microphone has recently been developed that meets this standard, which operates down to a fraction of a hertz. Details of the microphone are given. Little appears to have been published on the overpressure and noise of modern multiple airbag systems, but early results [R. Hickling, ''The noise of the automotive safety air cushion,'' Noise Control Eng., May-June, 110-121 (1976)] provide a basic understanding of the phenomenon. Spectral data shows that peak overpressure occurs at about 2 to 3 Hz. A significant reduction in overpressure and noise can be achieved with an aspirating airbag, originally developed at General Motors, whose outer structure is inflated with gas from the inflator, and whose inner structure draws in air from the passenger compartment through one-way cloth valves. Tests have shown that such bags function well when impacted.
Designing a Sustainable Noise Mapping System Based on Citizen Scientists Smartphone Sensor Data
Shim, Eunyoung; Kim, Dohyeong; Woo, Hyekyung; Cho, Youngtae
2016-01-01
In this study, we attempted to assess the feasibility of collecting population health data via mobile devices. Specifically, we constructed noise maps based on sound information monitored by individuals’ smartphones. We designed a sustainable way of creating noise maps that can overcome the shortcomings of existing station-based noise-monitoring systems. Three hundred and nine Seoul residents aged 20–49 years who used Android-based smartphones were recruited, and the subjects installed a special application that we developed for this study. This application collected information on sound and geographical location every 10 min for 7 days. Using GIS, we were able to construct various types of noise maps of Seoul (e.g., daytime/nighttime and weekdays/weekends) using the information on sound and geographical location obtained via the users’ smartphones. Despite the public health importance of noise management, a number of countries and cities lack a sustainable system to monitor noise. This pilot study showed the possibility of using the smartphones of citizen scientists as an economical and sustainable way of monitoring noise, particularly in an urban context in developing countries. PMID:27626273
An Integrated Real-Time Beamforming and Postfiltering System for Nonstationary Noise Environments
Gannot Sharon
2003-01-01
Full Text Available We present a novel approach for real-time multichannel speech enhancement in environments of nonstationary noise and time-varying acoustical transfer functions (ATFs. The proposed system integrates adaptive beamforming, ATF identification, soft signal detection, and multichannel postfiltering. The noise canceller branch of the beamformer and the ATF identification are adaptively updated online, based on hypothesis test results. The noise canceller is updated only during stationary noise frames, and the ATF identification is carried out only when desired source components have been detected. The hypothesis testing is based on the nonstationarity of the signals and the transient power ratio between the beamformer primary output and its reference noise signals. Following the beamforming and the hypothesis testing, estimates for the signal presence probability and for the noise power spectral density are derived. Subsequently, an optimal spectral gain function that minimizes the mean square error of the log-spectral amplitude (LSA is applied. Experimental results demonstrate the usefulness of the proposed system in nonstationary noise environments.
Low frequency noise elimination technique for 24-bit Σ-Δ data acquisition systems
Qu, Shao-Bo; Robert, Olivier; Lognonné, Philippe; Zhou, Ze-Bing; Yang, Shan-Qing
2015-03-01
Low frequency 1/f noise is one of the key limiting factors of high precision measurement instruments. In this paper, digital correlated double sampling is implemented to reduce the offset and low frequency 1/f noise of a data acquisition system with 24-bit sigma delta (Σ-Δ) analog to digital converter (ADC). The input voltage is modulated by cross-coupled switches, which are synchronized to the sampling clock, and converted into digital signal by ADC. By using a proper switch frequency, the unwanted parasitic signal frequencies generated by the switches are avoided. The noise elimination processing is made through the principle of digital correlated double sampling, which is equivalent to a time shifted subtraction for the sampled voltage. The low frequency 1/f noise spectrum density of the data acquisition system is reduced to be flat down to the measurement frequency lower limit, which is about 0.0001 Hz in this paper. The noise spectrum density is eliminated by more than 60 dB at 0.0001 Hz, with a residual noise floor of (9 ± 2) nV/Hz1/2 which is limited by the intrinsic white noise floor of the ADC above its corner frequency.
Stimulated Brillouin scattering-induced phase noise in an interferometric fiber sensing system
Chen Wei; Meng Zhou; Zhou Hui-Juan; Luo Hong
2012-01-01
Stimulated Brillouin scattering-induced phase noise is harmful to interferometric fiber sensing systems. Thelocalized fluctuating model is used to study the intensity noise caused by the stimulated Brillouin scattering in a single-mode fiber.The phase noise structure is analyzed for an interferometric fiber sensing system,and an unbalanced Michelson interferometer with an optical path difference of 1 m,as well as the phase-generated carrier technique,is used to measure the phase noise.It is found that the phase noise is small when the input power is below the stimulated Brillouin scattering threshold,increases dramatically at first and then gradually becomes fiat when the input power is above the threshold,which is similar to the variation in relative intensity noise.It can be inferred that the increase in phase noise is mainly due to the broadening of the laser linewidth caused by stimulated Brillouin scattering,which is verified through linewidth measurements in the absence and presence of the stimulated Brillouin scattering.
Zhang, Fang
2014-06-16
The placement of the reference electrode (RE) in various bioelectrochemical systems is often varied to accommodate different reactor configurations. While the effect of the RE placement is well understood from a strictly electrochemistry perspective, there are impacts on exoelectrogenic biofilms in engineered systems that have not been adequately addressed. Varying distances between the working electrode (WE) and the RE, or the RE and the counter electrode (CE) in microbial fuel cells (MFCs) can alter bioanode characteristics. With well-spaced anode and cathode distances in an MFC, increasing the distance between the RE and anode (WE) altered bioanode cyclic voltammograms (CVs) due to the uncompensated ohmic drop. Electrochemical impedance spectra (EIS) also changed with RE distances, resulting in a calculated increase in anode resistance that varied between 17 and 31Ω (-0.2V). While WE potentials could be corrected with ohmic drop compensation during the CV tests, they could not be automatically corrected by the potentiostat in the EIS tests. The electrochemical characteristics of bioanodes were altered by their acclimation to different anode potentials that resulted from varying the distance between the RE and the CE (cathode). These differences were true changes in biofilm characteristics because the CVs were electrochemically independent of conditions resulting from changing CE to RE distances. Placing the RE outside of the current path enabled accurate bioanode characterization using CVs and EIS due to negligible ohmic resistances (0.4Ω). It is therefore concluded for bioelectrochemical systems that when possible, the RE should be placed outside the current path and near the WE, as this will result in more accurate representation of bioanode characteristics. © 2014 Wiley Periodicals, Inc.
Investigations of Physical Processes in Microgravity Relevant to Space Electrochemical Power Systems
Lvovich, Vadim F.; Green, Robert; Jakupca, Ian
2015-01-01
NASA has performed physical science microgravity flight experiments in the areas of combustion science, fluid physics, material science and fundamental physics research on the International Space Station (ISS) since 2001. The orbital conditions on the ISS provide an environment where gravity driven phenomena, such as buoyant convection, are nearly negligible. Gravity strongly affects fluid behavior by creating forces that drive motion, shape phase boundaries and compress gases. The need for a better understanding of fluid physics has created a vigorous, multidisciplinary research community whose ongoing vitality is marked by the continuous emergence of new fields in both basic and applied science. In particular, the low-gravity environment offers a unique opportunity for the study of fluid physics and transport phenomena that are very relevant to management of fluid - gas separations in fuel cell and electrolysis systems. Experiments conducted in space have yielded rich results. These results provided valuable insights into fundamental fluid and gas phase behavior that apply to space environments and could not be observed in Earth-based labs. As an example, recent capillary flow results have discovered both an unexpected sensitivity to symmetric geometries associated with fluid container shape, and identified key regime maps for design of corner or wedge-shaped passive gas-liquid phase separators. In this presentation we will also briefly review some of physical science related to flight experiments, such as boiling, that have applicability to electrochemical systems, along with ground-based (drop tower, low gravity aircraft) microgravity electrochemical research. These same buoyancy and interfacial phenomena effects will apply to electrochemical power and energy storage systems that perform two-phase separation, such as water-oxygen separation in life support electrolysis, and primary space power generation devices such as passive primary fuel cell.
Zahra Etesami
2017-05-01
Full Text Available We investigate harvesting electrical energy from Gaussian white, Gaussian colored, telegraph and random phase-random amplitude (RARP noises, using linear and nonlinear electromechanical systems. We show that the output power of the linear system with one or two degrees of freedom, is maximum for the Gaussian white noise. The response of the system with two degrees of freedom is widened in a larger frequency domain compared to that of a single degree of freedom system. A nonlinear system generates more power than a linear one.
Effect of Asymmetry in a Bistable System Subject to Multiplicative Colored Noise
无
2007-01-01
By the method of the stochastic energetics, we investigate the stochastic resonance (SR) phenomenon of an overdamped Brown particle in an asymmetric bistable potential, driven by external periodical signal and multiplicative noise. The expressions have been obtained for the quasi-steady-state probability distribution function. It is found that the input energy (IE) pumped into the system by the external driving shows an SR-like behavior as a function of the noise strength, whereas the IE turns to be a monotonic function of the correlation time of the noise. The effect of potential asymmetry is also studied on SR and IE.
Aeroacoustic Noise Analysis of a Locomotive Cooling System Ducts and Structure Optimization
Shanshan Li
2015-07-01
Full Text Available Aero acoustic noise of a locomotive cab cooling system ducts was analyzed by method of Computational Fluid Dynamics (CFD and Computational Aero acoustic (CAA approach. Flow characteristic of the ducts was analyzed by CFD software, then near-field and far-field aero acoustic noise was forecasted with BNS model and FW-H model respectively. Duct structure was optimized according to the analysis of flow field and sound field. Results indicated that noise characteristic of sensitive frequency band at the position of human ear with the optimized duct has a significant improvement.
Niessen, R. [Sulzer-Escher Wyss GmbH, Lindau (Germany)
1998-09-01
The operator`s order discussed by the paper was for planning and performance of backfitting measures for noise pollution abatement in an existing cooling tower system equipped with sound attenuation devices. Although the existing plant was operating in compliance with the legal noise emission limits, residents of neighbouring dwellings had been complaining about noise pollution. (orig./CB) [Deutsch] Die Aufgabe, eine nachtraegliche Massnahme zur Laermminderung an einer bestehenden, mit Schalldaempfern ausgeruesteten Anlage zu planen und durchzufuehren, wurde vom Betreiber einer Rueckkuehlanlage gestellt. Der vom Gesetzgeber definierte Grenzwert fuer den Nachtbetrieb wurde mit der bestehenden Anlage zwar erreicht, doch die Anwohner fuehlten eine Belaestigung durch den Anlagenbetrieb. (orig./GL)
Allen, Glen
1988-01-01
A 45 month effort for the development of a 20 GHz, low-noise, low-cost receiver for digital, satellite communication system, ground terminal applications is discussed. Six proof-of-concept receivers were built in two lots of three each. Performance was generally consistent between the two lots. Except for overall noise figure, parameters were within or very close to specification. While noise figure was specified as 3.5 dB, typical performance was measured at 3.0 to 5.5 dB, over the full temperature range of minus 30 C to plus 75 C.
V-band low-noise integrated circuit receiver. [for space communication systems
Chang, K.; Louie, K.; Grote, A. J.; Tahim, R. S.; Mlinar, M. J.; Hayashibara, G. M.; Sun, C.
1983-01-01
A compact low-noise V-band integrated circuit receiver has been developed for space communication systems. The receiver accepts an RF input of 60-63 GHz and generates an IF output of 3-6 GHz. A Gunn oscillator at 57 GHz is phaselocked to a low-frequency reference source to achieve high stability and low FM noise. The receiver has an overall single sideband noise figure of less than 10.5 dB and an RF to IF gain of 40 dB over a 3-GHz RF bandwidth. All RF circuits are fabricated in integrated circuits on a Duroid substrate.
Savaux, Vincent
2014-01-01
This book presents an algorithm for the detection of an orthogonal frequency division multiplexing (OFDM) signal in a cognitive radio context by means of a joint and iterative channel and noise estimation technique. Based on the minimum mean square criterion, it performs an accurate detection of a user in a frequency band, by achieving a quasi-optimal channel and noise variance estimation if the signal is present, and by estimating the noise level in the band if the signal is absent. Organized into three chapters, the first chapter provides the background against which the system model is pr
A low-noise current-sensitive amplifier-discriminator system for beta particle counting.
Sephton, J P; Johansson, L C; Williams, J M
2008-01-01
NPL has developed a low-noise current amplifier/discriminator system for radionuclides that emit low-energy electrons and X-rays. The new beta amplifier is based on the low-noise Amptek A-250 operational amplifier. The design has been configured for optimum signal to noise ratio. The new amplifier is described and results obtained using primarily electron-capture decaying radionuclides are presented. The new amplifier gives rise to higher particle detection efficiency than the previously used Atomic Energy of Canada Limited-designed amplifier. This is shown by measurements of (54)Mn and (65)Zn. The counting plateaux are significantly longer and have reduced gradients.
An algorithm for simulation of electrochemical systems with surface-bulk coupling strategies
Buoni, Matthew; Petzold, Linda
2010-01-01
In Buoni and Petzold (2007) [13] we described a new algorithm for simulation of electrochemical systems on two-dimensional irregular, time-dependent domains. Here we show how to extend the algorithm to three dimensions. We demonstrate our three-dimensional algorithm by simulating copper electrodeposition into a via structure. This problem poses challenges for the coupling of the dilute electrolyte (bulk) model to the surface dynamics model, which involves a complex network of reactions. To handle this coupling, we introduce a new and highly effective semi-implicit method.
无
2000-01-01
The electrochemical quartz crystal impedance system (EQCIS) has been used for the study of a partially immersed Au electrode in 0.2 mol/L NaClO4 aqueous solution.The influences of the immersed area and height of the electrode on the EQCIS responses were evaluated,showing the highest response sensitivity to liquid loading at the center of the piezoelectric quartz crystal electrode.The increase in the immersed height of the Au electrode at oxygen reduction potentials during potential cycling was measured by this technique.
Stochastic resonance in a time-delayed bistable system driven by trichotomous noise
Zhou, Bingchang; Lin, Dandan
2017-03-01
This paper studies the phenomenon of stochastic resonance (SR) in a bistable system with time delay driven by trichotomous noise. Firstly, a method of numerical simulation for trichotomous noise is presented and its accuracy is checked using normalized autocorrelation function. Then the effects of feedback strength and time delay on the system responses and signal-to-noise ratio (SNR) are studied. The results show that negative feedback strength is more beneficial than positive to promote SR. The effect of time delay on SR is related to the value of feedback strength. The influence of the signal amplitude and frequency on SR is also investigated. It is found that large amplitude and small frequency of the signal can promote the occurrence of SR. Finally, the influence of the amplitude and stationary probability of trichotomous noise on SNR are discussed.
Stochastic resonance in a time-delayed bistable system driven by trichotomous noise
Zhou, Bingchang; Lin, Dandan
2016-10-01
This paper studies the phenomenon of stochastic resonance (SR) in a bistable system with time delay driven by trichotomous noise. Firstly, a method of numerical simulation for trichotomous noise is presented and its accuracy is checked using normalized autocorrelation function. Then the effects of feedback strength and time delay on the system responses and signal-to-noise ratio (SNR) are studied. The results show that negative feedback strength is more beneficial than positive to promote SR. The effect of time delay on SR is related to the value of feedback strength. The influence of the signal amplitude and frequency on SR is also investigated. It is found that large amplitude and small frequency of the signal can promote the occurrence of SR. Finally, the influence of the amplitude and stationary probability of trichotomous noise on SNR are discussed.
Non-Linear Noise Contributions in Highly Dispersive Optical Transmission Systems
Matera, Francesco
2016-01-01
This article reports an analytical investigation, confirmed by numerical simulations, about the non-linear noise contribution in single-channel systems adopting generic modulation-detection formats in long links with both managed and unmanaged dispersion compensation and its impact in system performance. This noise contribution is expressed in terms of a pulse non-linear interaction length and permits a simple calculation of the Q-factor. Results point out the dependence of this non-linear noise on the number of amplifiers spans, N, according to the adopted chromatic dispersion compensation scheme, the modulation-detection format, and the signal baud rate. It is also shown how the effects of polarization multiplexing can be taken into account and how this single-channel non-linear noise contribution can be used in a wavelength-division multiplexing (WDM) environment.
Gautier, Pierre-Etienne; Hanson, Carl; Hemsworth, Brian; Nelson, James; Schulte-Werning, Burkhard; Thompson, David; Vos, Paul
2012-01-01
This volume contains the contributions to the 10th International Workshop on Railway Noise, held October 18–22, 2010, in Nagahama, Japan, organized by the Railway Technical Research Institute (RTRI), Japan. With 11 sessions and 3 poster sessions, the workshop featured presentations by international leaders in the field of railway noise and vibration. All subjects relating to 1. prospects, legal regulation, and perception; 2. wheel and rail noise; 3. structure-borne noise and squeal noise; 4. ground-borne vibration; 5. aerodynamic noise and micro-pressure waves from tunnel portals; 6. interior noise and sound barriers; and 7. prediction, measurements, and monitoring are addressed here. This book is a useful “state-of-the-art” reference for scientists and engineers involved in solving environmental problems of railways.
Lieber, Lysbeth; Golub, Robert (Technical Monitor)
2000-01-01
This Final Report has been prepared by AlliedSignal Engines and Systems, Phoenix, Arizona, documenting work performed during the period May 1997 through June 1999, under the Small Engines Technology Program, Contract No. NAS3-27483, Task Order 13, ANOPP Noise Prediction for Small Engines. The report specifically covers the work performed under Subtasks 4, 5 and 6. Subtask 4 describes the application of a semi-empirical procedure for jet noise prediction, subtask 5 describes the development of a procedure to predict the effects of wing shielding, and subtask 6 describes the results of system studies of the benefits of the new noise technology on business and regional aircraft.
Noise analysis of fluid-valve system in a linear compressor using CAE
Lee, Jun Ho; Jeong, Weui Bong [Pusan National Univ., Busan (Korea, Republic of); Kim, Dang Ju [LOCUS Co., Ltd., Busan (Korea, Republic of)
2009-07-01
A linear compressor in a refrigerator uses piston motion to transfer refrigerant so its efficiency is higher than a previous reciprocal compressor. Because of interaction between refrigerant and valves system in the linear compressor, however, noise has been a main issue. In spite of doing many experimental researches, there is no way to rightly predict the noise. In order to solve this limitation, the CAE analysis is applied. For giving credit to these computational data, all of the data are experimentally validated.
Noise-Induced Phase Locking and Frequency Mixing in an Optical Bistable System with Delayed Feedback
Misono, Masatoshi; Miyakawa, Kenji
2011-11-01
The interplay between stochastic resonance (SR) and coherence resonance (CR) is experimentally studied in an optical bistable system with a time-delayed feedback loop. We demonstrate that the phase of the noise-induced motion is locked to that of the periodic input when the ratio of their frequencies is a simple rational number. We also demonstrate that the interplay between SR and CR generates frequency-mixed modes, and that the efficiency of frequency mixing is enhanced by the optimum noise.
Zhu Jin; Xi Hongsheng; Xiao Xiaobo; Ji Haibo
2007-01-01
Robust LQG problems of discrete-time Markovian jump systems with uncertain noises are investigated.The problem addressed is the construction of perturbation upper bounds on the uncertain noise covariances so as to guarantee that the deviation of the control performance remains within the precision prescribed in actual problems.Furthermore, this regulator is capable of minimizing the worst performance in an uncertain case. A numerical example is exploited to show the validity of the method.
Triple play service under the impact of nonstationary noise in a DSL system: an Amazon approach
de Souza, Lamartine V.; Cardoso, Diego; Silva, Marcelino; Seruffo, Marcos; Francês, Carlos R. L.; Costa, João C. W. A.; Castro, Agostinho L. S.; Cavalcante, Gervásio; Rius i Riu, Jaume
2007-09-01
The Brazilian Amazon has sui generis characteristics that affect strongly the communication technologies, such as high humidity and temperature. These characteristics cause impact in the existent infrastructure, especially in twisted-pair copper lines. At the moment, new services are based on multimedia applications, as voice over internet protocol (VoIP), video on demand (VoD), and internet protocol television (IPTV). Such services use digital broadband networks such as ADSL2+ (Asymmetric Digital Subscriber Line) to transmit the data. Broadband services require data rates which can only be achieved by using relatively high spectrum frequencies. At high frequencies the DSL signal is more susceptible to external noise sources, such as radio frequency interference and impulsive noise. For this purpose, an experimental setup has been built at UFPA that consists of noise generator, traffic generator, real cables, modems and DSLAM (digital subscriber line access multiplexer). This paper aims at characterizing how the noise impacts on triple play services for a broadband system using a DSL loop on Amazon environment. The objective of the noise impact experimentation is to observe the behavior of a DSL system under more realistic but controlled line conditions. Metrics as lost packet, jitter, latency, and throughput are used to characterize the triple play service in a DSL loop under the noise impact. Through the real experiments and controlled loop conditions, this paper allow identify, from application level point of view, how robust DSL system is in respect to noise occurrence. Additionally, it is described a methodology for noise impact measurements using a DSL system.
Deep sub electron noise readout in CCD systems using digital filtering techniques
Cancelo, Gustavo; Moroni, Guillermo Fernandez; Treptow, Ken; Zmuda, Ted; Diehl, Tom
2011-01-01
Scientific CCDs designed in thick high resistivity silicon (Si) are excellent detectors for astronomy, high energy and nuclear physics, and instrumentation. Many applications can benefit from CCDs ultra low noise readout systems. The present work shows how sub electron noise CCD images can be achieved using digital signal processing techniques. These techniques allow readout bandwidths of up to 10 K pixels per second and keep the full CCD spatial resolution and signal dynamic range.
Delay-Modulated RF Tag System Concept Using Ultrawideband Noise Radar Waveforms
2011-01-01
Radio frequency (RF) tags have been widely used in inventory tracking, environmental monitoring, battlefield situational awareness, and combat identification due to their low cost, small size, and wireless functionality. This paper explores the application of active RF tags in outdoor environments responding to random noise radar interrogations with predetermined messages. A conceptual system design for communication between radar and RF tags using ultrawideband (UWB) noise waveforms is propo...
Signal-to-noise performance analysis of streak tube imaging lidar systems. I. Cascaded model.
Yang, Hongru; Wu, Lei; Wang, Xiaopeng; Chen, Chao; Yu, Bing; Yang, Bin; Yuan, Liang; Wu, Lipeng; Xue, Zhanli; Li, Gaoping; Wu, Baoning
2012-12-20
Streak tube imaging lidar (STIL) is an active imaging system using a pulsed laser transmitter and a streak tube receiver to produce 3D range and intensity imagery. The STIL has recently attracted a great deal of interest and attention due to its advantages of wide azimuth field-of-view, high range and angle resolution, and high frame rate. This work investigates the signal-to-noise performance of STIL systems. A theoretical model for characterizing the signal-to-noise performance of the STIL system with an internal or external intensified streak tube receiver is presented, based on the linear cascaded systems theory of signal and noise propagation. The STIL system is decomposed into a series of cascaded imaging chains whose signal and noise transfer properties are described by the general (or the spatial-frequency dependent) noise factors (NFs). Expressions for the general NFs of the cascaded chains (or the main components) in the STIL system are derived. The work presented here is useful for the design and evaluation of STIL systems.
Sadeghi, Saman; Thompson, Michael
2010-01-01
It is evident that complex animate materials, which operate far from equilibrium, exhibit sensory responses to the environment through emergent patterns. Formation of such patterns is often the underlying mechanism of an active response to environmental changes and can be interpreted as a result of the distributed parallel information processing taking place within the material. Such emergent patterns are not limited to biological entities; indeed there is a wide range of complex nonlinear dissipative systems which exhibit interesting emergent patterns within a range of parameters. As one example, the present paper describes the detection of emergent phenomena associated with surface electrochemical processes that allow the system to respond to input information through evolving patterns in space and time. Associative mapping of this sort offers the opportunity to devise an electrochemical cognitive system (ECS), where pattern formation can be looked at as a macroscopic phenomenon resulting from the extensive distributive computing that occurs at the microscopic level. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.
Properties of effective noise for systems with quenched randomness
Majaniemi, Sami
2001-03-01
The fluid-fluid phase boundary wandering in a disordered medium such as a Hele-Shaw cell filled with porous material experiences exotic correlations which are quite different from the static correlations characterizing the material properties of the medium. The equation of motion for the phase boundary is obtained by projecting out the bulk degrees of freedom. It is used to determine the noise properties of the nonlinear Langevin equation describing the dynamics of lower dimensional collective coordinates like interfaces and contact lines. Effect of local conservation law at the level of bulk dynamics changes the universal properties of the fluctuation of collective coordinates in a non-trivial way. As a particular example we use the refinements of the spontaneous imbibition model originally introduced for wetting of random medium [1]. [1] M. Dubé, M. Rost, K.R. Elder, M. Alava, S. Majaniemi, T. Ala-Nissila, Eur. Phys. J. B 15, 701 (2000).
Shot noises of spin and charge currents in a ferromagnet-quantum-dot-ferromagnet system
Hong-kang ZHAO; Jian WANG
2008-01-01
We have investigated the shot noises of charge and spin current by considering the spin polarized electron tunneling through a ferromagnet-quantum-dotferromagnet system.We have derived the spin polarized current noise matrix,from which we can derive general expressions of shot noises associated with charge and spin currents.The spin and charge currents are intimately related to the polarization angles,and they behave quite differently from each other.The shot noise of charge current is symmetric about the gate voltage whose structure is modified by the Zeeman field considerably.There exists oscillations in spin current shot noise in the absence of source-drain bias at zero temperature,and it is asym metric in the positive and negative regimes of sourcedrain voltage. The shot noise of spin current behaves quite differently from the shot noise of charge current,since the spin current components Isx,Isy oscillate sinusoidally with the frequency ωγ in the γth lead,while the Isz component of spin current is independent of time.
Measurements of Low Frequency Noise of Infrared Photo-Detectors with Transimpedance Detection System
Ciura Łukasz
2014-08-01
Full Text Available The paper presents the method and results of low-frequency noise measurements of modern mid-wavelength infrared photodetectors. A type-II InAs/GaSb superlattice based detector with nBn barrier architecture is compared with a high operating temperature (HOT heterojunction HgCdTe detector. All experiments were made in the range 1 Hz - 10 kHz at various temperatures by using a transimpedance detection system, which is examined in detail. The power spectral density of the nBn’s dark current noise includes Lorentzians with different time constants while the HgCdTe photodiode has more uniform 1/f - shaped spectra. For small bias, the low-frequency noise power spectra of both devices were found to scale linearly with bias voltage squared and were connected with the fluctuations of the leakage resistance. Leakage resistance noise defines the lower noise limit of a photodetector. Other dark current components give raise to the increase of low-frequency noise above this limit. For the same voltage biasing devices, the absolute noise power densities at 1 Hz in nBn are 1 to 2 orders of magnitude lower than in a MCT HgCdTe detector. In spite of this, low-frequency performance of the HgCdTe detector at ~ 230K is still better than that of InAs/GaSb superlattice nBn detector.
Evaluating the performance of active noise control systems in commercial and industrial applications
Depies, C.; Deneen, S.; Lowe, M.; Wise, S.
1995-06-01
Active sound cancellation technology is increasingly being used to quiet commercial and industrial air-moving devices. Engineers and designers are implementing active or combination active/passive technology to control sound quality in the workplace and the acoustical environment in residential areas near industrial facilities. Sound level measurements made before and after the installation of active systems have proved that significant improvements in sound quality can be obtained even if there is little or no change in the NC/RC or dBA numbers. Noise produced by centrifugal and vane-axial fans, pumps and blowers, commonly used for ventilation and material movement in industry, are frequently dominated by high amplitude, tonal noise at low frequencies. And the low-frequency noise produced by commercial air handlers often has less tonal and more broadband characteristics, resulting in audible duct rumble noise and objectionable room spectrums. Because the A-weighting network, which is commonly used for industrial noise measurements, de-emphasizes low frequencies, its single number rating can be misleading in terms of judging the overall subjective sound quality in impacted areas and assessing the effectiveness of noise control measures. Similarly, NC values, traditionally used for commercial HVAC acoustical design criteria, can be governed by noise at any frequency and cannot accurately depict human judgment of the aural comfort level. Analyses of frequency spectrum characteristics provide the most effective means of assessing sound quality and determining mitigative measures for achieving suitable background sound levels.
ClassTalk system for predicting and visualizing speech in noise in classrooms
Hodgson, Murray
2002-11-01
This paper discusses the ClassTalk system for modeling, predicting and visualizing speech in noise in classrooms. Modeling involves defining the classroom geometry, sources, sound-absorbing features, and receiver positions. Empirical models, used to predict speech and noise levels, and reverberation times, are described. Male or female speech sources, and overhead-, slide-, or LCD-projector, or ventilation-outlet noise sources, can have four output levels; values are assigned based on ranges of values found from published data and measurements. ClassTalk visualizes the floor plan, speech- and noise-source positions, and the receiver position. The user can walk through the room at will. In real time, six quantities--background-noise level, speech level, signal-to-noise level difference, useful-to-detrimental energy fraction (U50), Speech Transmission Index, and speech intelligibility--are displayed, along with occupied and unoccupied reverberation times. An example of a large classroom before and after treatment is presented. The future development of improved prediction models and of the sound module, which will auralize speech in noise with reverberation, is discussed.
Near-Capacity Coding for Discrete Multitone Systems with Impulse Noise
Kschischang Frank R
2006-01-01
Full Text Available We consider the design of near-capacity-achieving error-correcting codes for a discrete multitone (DMT system in the presence of both additive white Gaussian noise and impulse noise. Impulse noise is one of the main channel impairments for digital subscriber lines (DSL. One way to combat impulse noise is to detect the presence of the impulses and to declare an erasure when an impulse occurs. In this paper, we propose a coding system based on low-density parity-check (LDPC codes and bit-interleaved coded modulation that is capable of taking advantage of the knowledge of erasures. We show that by carefully choosing the degree distribution of an irregular LDPC code, both the additive noise and the erasures can be handled by a single code, thus eliminating the need for an outer code. Such a system can perform close to the capacity of the channel and for the same redundancy is significantly more immune to the impulse noise than existing methods based on an outer Reed-Solomon (RS code. The proposed method has a lower implementation complexity than the concatenated coding approach.
A DFB Fiber Laser Sensor System with Ultra-High Resolution and Its Noise Analysis
Hao Xiao; Fang Li; Jun He; Yu-Liang Liu
2008-01-01
A distributed feedback fiber laser (DFB FL) sensor system with ultra-high resolution is described. The sensor is made by writing distributed feedback structures into a high gain active fiber, and the system employs an unbalanced Michelson interferometer to translate laser wavelength shifts induced by weak measurands into phase shifts. A digital phase generated carrier demodulation scheme is introduced to achieve ultra-high resolution interrogation. A detailed noise analysis of the system is presented, and it is shown that the system resolution is limited by the frequency noise of the DFB FL.
Biased transportations in a spatially asymmetric system at the nano-scale under thermal noise
无
2010-01-01
Under the theory of ratchet effect for mesoand macro-scale systems, the additional perturbation with a long time correlation and the breaking of spatial inversion symmetry are two main ingredients to bring unidirected transportations. With the help of a simple model system, we show that a spatially asymmetric system of the nano-scale length may induce biased transportations under thermal noise.
Noise-induced multistability in chemical systems: Discrete versus continuum modeling.
Duncan, Andrew; Liao, Shuohao; Vejchodský, Tomáš; Erban, Radek; Grima, Ramon
2015-04-01
The noisy dynamics of chemical systems is commonly studied using either the chemical master equation (CME) or the chemical Fokker-Planck equation (CFPE). The latter is a continuum approximation of the discrete CME approach. It has recently been shown that for a particular system, the CFPE captures noise-induced multistability predicted by the CME. This phenomenon involves the CME's marginal probability distribution changing from unimodal to multimodal as the system size decreases below a critical value. We here show that the CFPE does not always capture noise-induced multistability. In particular we find simple chemical systems for which the CME predicts noise-induced multistability, whereas the CFPE predicts monostability for all system sizes.
Soury, Hamza
2016-06-29
The Gaussian distribution is typically used to model the additive noise affecting communication systems. However, in many cases the noise cannot be modeled by a Gaussian distribution. In this thesis, we investigate the performance of different communication systems perturbed by non-Gaussian noise. Three families of noise are considered in this work, namely the generalized Gaussian noise, the Laplace noise/interference, and the impulsive noise that is modeled by an α-stable distribution. More specifically, in the first part of this thesis, the impact of an additive generalized Gaussian noise is studied by computing the average symbol error rate (SER) of one dimensional and two dimensional constellations in fading environment. We begin by the simple case of two symbols, i.e. binary phase shift keying (BPSK) constellation. From the results of this constellation, we extended the work to the average SER of an M pulse amplitude modulation (PAM). The first 2 − D constellation is the M quadrature amplitude modulation (QAM) (studied for two geometric shapes, namely square and rectangular), which is the combination of two orthogonal PAM signals (in-phase and quadrature phase PAM). In the second part, the system performance of a circular constellation, namely M phase shift keying (MPSK) is studied in conjunction with a Laplace noise with independent noise components. A closed form and an asymptotic expansion of the SER are derived for two detectors, maximum likelihood and minimum distance detectors. Next, we look at the intra cell interference of a full duplex cellular network which is shown to follow a Laplacian distribution with dependent, but uncorrelated, complex components. The densities of that interference are expressed in a closed form in order to obtain the SER of several communication systems (BPSK, PAM, QAM, and MPSK). Finally, we study the statistics of the α-stable distribution. Those statistics are expressed in closed form in terms of the Fox H function and
Effects of small time delay on a bistable system subject to Levy stable noise
Huang Jiamin; Tao Weiming; Xu Bohou, E-mail: taowm@zju.edu.cn [Department of Mechanics, Zhejiang University, Hangzhou 310027 (China)
2011-09-23
Levy stable noise is often used to describe impulsive noise bursting in communication systems. This paper investigates the effects of small time delay on a bistable system driven by an aperiodic bipolar pulse signal and Levy stable noise. We obtain the dynamical probability density of the system response by solving the approximated time-delayed fractional Fokker-Planck equation (FFPE) via an implicit finite difference method. A new approach to evaluate the system response time is presented. The bit error rate (BER) is employed to measure the performance of the bistable system in detecting binary signals. The theoretical BER is validated by the Monte-Carlo simulation. We find that the existence of time delay can change both the drift term and the diffusion coefficient in time-delayed FFPE. For small noise intensity, the time delay extends the system response time and thus reduces the detection performance. However, effects of this kind will fade away with the increase of noise intensity. (paper)
National Aeronautics and Space Administration — In this project IntAct Labs proposes to develop a novel system to increase loop closure for water treatment in regenerative life support using bio-electrochemical...
Nanoscale Electrochemical Sensor Arrays: Redox Cycling Amplification in Dual-Electrode Systems.
Wolfrum, Bernhard; Kätelhön, Enno; Yakushenko, Alexey; Krause, Kay J; Adly, Nouran; Hüske, Martin; Rinklin, Philipp
2016-09-20
Micro- and nanofabriation technologies have a tremendous potential for the development of powerful sensor array platforms for electrochemical detection. The ability to integrate electrochemical sensor arrays with microfluidic devices nowadays provides possibilities for advanced lab-on-a-chip technology for the detection or quantification of multiple targets in a high-throughput approach. In particular, this is interesting for applications outside of analytical laboratories, such as point-of-care (POC) or on-site water screening where cost, measurement time, and the size of individual sensor devices are important factors to be considered. In addition, electrochemical sensor arrays can monitor biological processes in emerging cell-analysis platforms. Here, recent progress in the design of disease model systems and organ-on-a-chip technologies still needs to be matched by appropriate functionalities for application of external stimuli and read-out of cellular activity in long-term experiments. Preferably, data can be gathered not only at a singular location but at different spatial scales across a whole cell network, calling for new sensor array technologies. In this Account, we describe the evolution of chip-based nanoscale electrochemical sensor arrays, which have been developed and investigated in our group. Focusing on design and fabrication strategies that facilitate applications for the investigation of cellular networks, we emphasize the sensing of redox-active neurotransmitters on a chip. To this end, we address the impact of the device architecture on sensitivity, selectivity as well as on spatial and temporal resolution. Specifically, we highlight recent work on redox-cycling concepts using nanocavity sensor arrays, which provide an efficient amplification strategy for spatiotemporal detection of redox-active molecules. As redox-cycling electrochemistry critically depends on the ability to miniaturize and integrate closely spaced electrode systems, the
Energy Diffusion in Harmonic System with Conservative Noise
Basile, Giada; Olla, Stefano
2014-06-01
We prove diffusive behaviour of the energy fluctuations in a system of harmonic oscillators with a stochastic perturbation of the dynamics that conserves energy and momentum. The results concern pinned systems in any dimension, or unpinned systems in dimension.
Liang, Yuxiang; Feng, Huajun; Shen, Dongsheng; Long, Yuyang; Li, Na; Zhou, Yuyang; Ying, Xianbin; Gu, Yuan; Wang, Yanfeng
2016-08-01
This paper introduces a novel composite anode that uses light to enhance current generation and accelerate biofilm formation in bioelectrochemical systems. The composite anode is composed of 316L stainless steel substrate and a nanostructured α-Fe2O3 photocatalyst (PSS). The electrode properties, current generation, and biofilm properties of the anode are investigated. In terms of photocurrent, the optimal deposition and heat-treatment times are found to be 30 min and 2 min, respectively, which result in a maximum photocurrent of 0.6 A m-2. The start-up time of the PSS is 1.2 days and the maximum current density is 2.8 A m-2, twice and 25 times that of unmodified anode, respectively. The current density of the PSS remains stable during 20 days of illumination. Confocal laser scanning microscope images show that the PSS could benefit biofilm formation, while electrochemical impedance spectroscopy indicates that the PSS reduce the charge-transfer resistance of the anode. Our findings show that photo-electrochemical interaction is a promising way to enhance the biocompatibility of metal anodes for bioelectrochemical systems.
Unlu, Murat
Magnetic field effects on electrochemical reactions have been studied and shown to influence kinetics and dynamics. Recently, our group has introduced a novel method to establish magnetic field effects by incorporating inert, magnetic microparticles onto the electrode structure. This modification improved several electrochemical systems including modified electrodes, alkaline batteries, and fuel cells. This dissertation describes the applicability of magnetic microparticles and the understanding of magnetic field effects in modified electrodes, alkaline batteries, and paste electrodes. Magnetic effects are studied on electrodes that are coated with an ion exchange polymer that embeds chemically inert, commercial, magnetic microparticles. The flux (electrolysis current) of redox probe to the magnetically modified system is compared to a similar non-magnetic electrode. Flux enhancements of 60% are achieved at magnetically modified electrode as compared to non-magnetic controls. In addition to modifying electrode surfaces, the incorporation of magnetic microparticles into the electrode material itself establishes a 20% increase in flux. Possible magnetic field effects are evaluated. Study of samarium cobalt modified electrolytic manganese dioxide, EMD electrodes further establish a magnetic effect on alkaline cathode performance. Magnetic modification improves alkaline battery performance in primary and secondary applications. The reaction mechanism is examined through voltammetric methods. This work also includes coating protocols to produce inert magnetic microparticles with high magnetic content. Magnetite powders are encapsulated in a polymer matrix by dispersion polymerization. Composite particles are examined in proton exchange membrane fuel cells to study carbon monoxide tolerance.
An electrochemical system for efficiently harvesting low-grade heat energy
Lee, Seok Woo; Yang, Yuan; Lee, Hyun-Wook; Ghasemi, Hadi; Kraemer, Daniel; Chen, Gang; Cui, Yi
2014-05-01
Efficient and low-cost thermal energy-harvesting systems are needed to utilize the tremendous low-grade heat sources. Although thermoelectric devices are attractive, its efficiency is limited by the relatively low figure-of-merit and low-temperature differential. An alternative approach is to explore thermodynamic cycles. Thermogalvanic effect, the dependence of electrode potential on temperature, can construct such cycles. In one cycle, an electrochemical cell is charged at a temperature and then discharged at a different temperature with higher cell voltage, thereby converting heat to electricity. Here we report an electrochemical system using a copper hexacyanoferrate cathode and a Cu/Cu2+ anode to convert heat into electricity. The electrode materials have low polarization, high charge capacity, moderate temperature coefficients and low specific heat. These features lead to a high heat-to-electricity energy conversion efficiency of 5.7% when cycled between 10 and 60 °C, opening a promising way to utilize low-grade heat.
An electrochemical system for efficiently harvesting low-grade heat energy.
Lee, Seok Woo; Yang, Yuan; Lee, Hyun-Wook; Ghasemi, Hadi; Kraemer, Daniel; Chen, Gang; Cui, Yi
2014-05-21
Efficient and low-cost thermal energy-harvesting systems are needed to utilize the tremendous low-grade heat sources. Although thermoelectric devices are attractive, its efficiency is limited by the relatively low figure-of-merit and low-temperature differential. An alternative approach is to explore thermodynamic cycles. Thermogalvanic effect, the dependence of electrode potential on temperature, can construct such cycles. In one cycle, an electrochemical cell is charged at a temperature and then discharged at a different temperature with higher cell voltage, thereby converting heat to electricity. Here we report an electrochemical system using a copper hexacyanoferrate cathode and a Cu/Cu(2+) anode to convert heat into electricity. The electrode materials have low polarization, high charge capacity, moderate temperature coefficients and low specific heat. These features lead to a high heat-to-electricity energy conversion efficiency of 5.7% when cycled between 10 and 60 °C, opening a promising way to utilize low-grade heat.
Bing Wang; Xiuqing Wu
2008-01-01
@@ Considering a single-mode laser system with cross-correlated additive colored noise and multiplicative colored noise, we study the effects of correlation among noises on the normalized intensity correlation function C(s).C(s) is derived by means of the projection operator method.
Influence of aqueous phase on electrochemical biocorrosion tests in diesel/water systems
Bento, F.M. [Dept. of Soils, Faculty of Agronomy, UFRGS, 7712 Bento Goncalves Avenue, CEP: 91540-001, POA, RS (Brazil); Englert, G.E.; Muller, I.L. [Dept. of Metallurgy, Biocorrosion and Biofilms Lab, UFRGS, 99 Osvaldo Aranha Avenue s.615D, CEP: 90035-190, POA, RS (Brazil); Gaylarde, C.C. [Dept. of Biophisics, UFRGS POA, RS (Brazil)
2004-08-01
Storage tanks containing microbially contaminated diesel oil are susceptible to corrosion. This process may be evaluated electrochemically in the laboratory using simulated storage systems containing diesel oil and an aqueous phase. The simulated aqueous phase must supply mineral nutrients for microbial growth, together with adequate electrical conductivity, without, however, being too corrosive, so as to allow the aggressive nature of the microbial metabolites to be detected. In this investigation, microbial growth was measured in six electrically conductive media overlaid with metropolitan diesel oil containing an additive package. The microorganisms were the filamentous fungi, Hormoconis resinae, Paecilomyces variotii and Aspergillus fumigatus, the bacterium Bacillus subtilis and the yeast Candida silvicola, all previously isolated from contaminated diesel oil. After 60 days incubation with pure or mixed inocula of these microorganisms, pH, conductivity and viable microorganisms were measured. The electrochemical behaviour of carbon steel ASTM 283-93-C was determined in each of the six media (uninoculated) and in selected inoculated medium via measurements of open circuit potential and potentiostatic polarization curves. The uptake of phosphate (corrosion inhibitor), microbial growth, pH, conductivity and anodic and cathodic polarization curves were assessed in the water phase after 30 and 60 days of incubation with each single species Aspergillus fumigatus and Hormoconis resinae and with the consortium. The medium which proved most appropriate was Bushnell-Haas medium modified by the omission of chlorides, which allowed satisfactory microbial growth and had low aggressivity towards the steel. The performance of electrochemical tests in aerated, rather than deaerated, electrolyte solutions is suggested to be important to allow the detection of microbial influence on passive film formation and stability. (Abstract Copyright [2004], Wiley Periodicals, Inc.)
Noise-induced standing waves in oscillatory systems with time-delayed feedback
Stich, Michael
2016-01-01
In oscillatory reaction-diffusion systems, time-delay feedback can lead to the instability of uniform oscillations with respect to formation of standing waves. Here, we investigate how the presence of additive, Gaussian white noise can induce the appearance of standing waves. Combining analytical solutions of the model with spatio-temporal simulations, we find that noise can promote standing waves in regimes where the deterministic uniform oscillatory modes are stabilized. As the deterministic phase boundary is approached, the spatio-temporal correlations become stronger, such that even small noise can induce standing waves in this parameter regime. With larger noise strengths, standing waves could be induced at finite distances from the (deterministic) phase boundary. The overall dynamics is defined through the interplay of noisy forcing with the inherent reaction-diffusion dynamics.
Noise reduction and estimation in multiple micro-electro-mechanical inertial systems
Waegli, Adrian; Skaloud, Jan; Guerrier, Stéphane; Eulàlia Parés, Maria; Colomina, Ismael
2010-06-01
This research studies the reduction and the estimation of the noise level within a redundant configuration of low-cost (MEMS-type) inertial measurement units (IMUs). Firstly, independent observations between units and sensors are assumed and the theoretical decrease in the system noise level is analyzed in an experiment with four MEMS-IMU triads. Then, more complex scenarios are presented in which the noise level can vary in time and for each sensor. A statistical method employed for studying the volatility of financial markets (GARCH) is adapted and tested for the usage with inertial data. This paper demonstrates experimentally and through simulations the benefit of direct noise estimation in redundant IMU setups.
Spatiotemporal complexity of a predator-prey system with the effect of noise and external forcing
Rao Feng [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China); Wang Weiming [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China)], E-mail: weimingwang2003@163.com; Li Zhenqing [Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093 (China)
2009-08-30
In this paper, we present a spatial version of the Ivlev-type predator-prey model which contains some important factors, such as noise on predator, external periodic forcing and diffusion processes on both predator and prey. From the numerical results, we know that noise or external periodic forcing can induce instability and enhance the oscillation of the species density, and the cooperation between noise and external periodic forcing inherent to the deterministic dynamics of periodically driven models gives rise to the appearance of a rich transport phenomenology. Furthermore, we demonstrate that the spatially extended system exhibits a resonant patterns and frequency-locking phenomena. Our results show that noise and external periodic forcing play a prominent role in the predator-prey model.
Effects of a periodic drive and correlated noise on birhythmic van der Pol systems
Yonkeu, R. Mbakob; Yamapi, R.; Filatrella, G.; Tchawoua, C.
2017-01-01
This paper considers the dynamics of a van der Pol birhythmic oscillator submitted both to colored noise and harmonic excitation. Applying the quasi-harmonic assumption to the corresponding Langevin equation we derive an approximated Fokker-Planck equation, that is compared with the results of computer simulations. We thus derive both the effects of the correlation time and the harmonic excitation on the parameter space where birhythmicity appears. In this region, we find that the multi-limit-cycle van der Pol oscillator reduces to an asymmetric bistable system where the sinusoidal drive intensity plays the role of asymmetric parameter, and noise can lead to stochastic bifurcations, consisting in a qualitative change of the stationary amplitude distribution. Under both influence of noise and harmonic excitation, the dynamics can be well characterized through the concepts of pseudo-potential, that regulates the low noise Arrhenius-like behavior.
Evaluation of an Asymmetric Bistable System for Signal Detection under LévyStable Noise
HUANG Jia-Min; TAO Wei-Ming; XU Bo-Hou
2012-01-01
We evaluate the performance of a typical asymmetric bistable system for detecting aperiodic signal under Lévy stable noise.A Grünwald-Letnikov implicit finite difference method is employed to solve the fractional FokkerPlanck equation numerically.The noise-induced stochastic resonance (SR) and the parameter-induced SR both exist in the asymmetric bistable systems.The increase of the skewness parameter γ may deteriorate the system performance.However,by tuning the system parameters,the effects of asymmetry on the system performance can be reduced.%We evaluate the performance of a typical asymmetric bistable system for detecting aperiodic signal under Levy stable noise. A Griinwald-Letnikov implicit finite difference method is employed to solve the fractional Fokker-Planck equation numerically. The noise-induced stochastic resonance (SR) and the parameter-induced SR both exist in the asymmetric bistable systems. The increase of the skewness parameter 7 may deteriorate the system performance. However, by tuning the system parameters, the effects of asymmetry on the system performance can be reduced.
Raquel Caballero-Águila
2015-01-01
Full Text Available The distributed fusion state estimation problem is addressed for sensor network systems with random state transition matrix and random measurement matrices, which provide a unified framework to consider some network-induced random phenomena. The process noise and all the sensor measurement noises are assumed to be one-step autocorrelated and different sensor noises are one-step cross-correlated; also, the process noise and each sensor measurement noise are two-step cross-correlated. These correlation assumptions cover many practical situations, where the classical independence hypothesis is not realistic. Using an innovation methodology, local least-squares linear filtering estimators are recursively obtained at each sensor. The distributed fusion method is then used to form the optimal matrix-weighted sum of these local filters according to the mean squared error criterion. A numerical simulation example shows the accuracy of the proposed distributed fusion filtering algorithm and illustrates some of the network-induced stochastic uncertainties that can be dealt with in the current system model, such as sensor gain degradation, missing measurements, and multiplicative noise.
The analysis of signal-to-noise ratio of airborne LIDAR system under state of motion
Hao, Huang; Lan, Tian; Zhang, Yingchao; Ni, Guoqiang
2010-11-01
This article gives an overview of airborne LIDAR (laser light detection and ranging) system and its application. By analyzing the transmission and reception process of laser signal, the article constructs a model of echo signal of the LIDAR system, and gives some basic formulas which make up the relationship of signal-to-noise ratio, for example, the received power, the dark noise power and so on. And this article carefully studies and analyzes the impact of some important parameters in the equation on the signal-to-noise ratio, such as the atmospheric transmittance coefficient, the work distance. And the matlab software is used to simulate the detection environment, and obtains a series values of signal-to-noise (SNR) ratio under different circumstances such as sunny day, cloudy day, day, night. And the figures which describe how the SNR of LIDAR system is influenced by the critical factors are shown in the article. Finally according to the series values of signal-to-noise ratio and the figures, the SNR of LIDAR system decreases as the distance increases, and the atmospheric transmittance coefficient caused by bad weather, and also high work temperature drops the SNR. Depending on these conclusions, the LIDAR system will work even better.
A New Adaptive Square-Root Unscented Kalman Filter for Nonlinear Systems with Additive Noise
Yong Zhou
2015-01-01
Full Text Available The Kalman filter (KF, extended KF, and unscented KF all lack a self-adaptive capacity to deal with system noise. This paper describes a new adaptive filtering approach for nonlinear systems with additive noise. Based on the square-root unscented KF (SRUKF, traditional Maybeck’s estimator is modified and extended to nonlinear systems. The square root of the process noise covariance matrix Q or that of the measurement noise covariance matrix R is estimated straightforwardly. Because positive semidefiniteness of Q or R is guaranteed, several shortcomings of traditional Maybeck’s algorithm are overcome. Thus, the stability and accuracy of the filter are greatly improved. In addition, based on three different nonlinear systems, a new adaptive filtering technique is described in detail. Specifically, simulation results are presented, where the new filter was applied to a highly nonlinear model (i.e., the univariate nonstationary growth model (UNGM. The UNGM is compared with the standard SRUKF to demonstrate its superior filtering performance. The adaptive SRUKF (ASRUKF algorithm can complete direct recursion and calculate the square roots of the variance matrixes of the system state and noise, which ensures the symmetry and nonnegative definiteness of the matrixes and greatly improves the accuracy, stability, and self-adaptability of the filter.
Anticorrosion performance of the coating/metal system by electrochemical impedance spectra
Yinghuai Zhang; Lining Xu; Minxu Lu; Pu Zhang
2008-01-01
In order to investigate the anticorrosion performance of the organic coating/metal system, electrochemical impedance spectra (EIS) were measured in the 3.5wt% NaC1 solution, the chemical component and the formation of corrosion products scale were analyzed by laser Raman microspectroscopy, and the pattern of the organic coating/metal system was observed by scanning electron microscopy (SEM). The characteristics and the delamination process of the organic coating/metal system were investigated systematically, and the emphases were on the transportation of the corrosive medium and the changes of the coating/metal interface. The results show that the impedance decreases at the initial immersion, then increases at the middle-immersion, and again decreases at last, which is related to the corrosion products scale. The concentration of Cl-in the coating, which destroys the corrosion products scale, increases with the immersion time.
Miller, John; Sibley, Lewis, B.; Wohlgemuth, John
1999-06-01
This report describes the results of a study that investigated the synergy between electrochemical capacitors (ECs) and flywheels, in combination with each other and with batteries, as energy storage subsystems in photovoltaic (PV) systems. EC and flywheel technologies are described and the potential advantages and disadvantages of each in PV energy storage subsystems are discussed. Seven applications for PV energy storage subsystems are described along with the potential market for each of these applications. A spreadsheet model, which used the net present value method, was used to analyze and compare the costs over time of various system configurations based on flywheel models. It appears that a synergistic relationship exists between ECS and flywheels. Further investigation is recommended to quantify the performance and economic tradeoffs of this synergy and its effect on overall system costs.
K. VIJAY KUMAR
2010-06-01
Full Text Available Solid polymer electrolyte system, polyethylene oxide (PEO complexed with potassium bicarbonate (KHCO3 salt was prepared by solution-cast technique. Several experimental techniques such as infrared radiation (IR, differential scanning calorimeter (DSC, and composition dependence conductivity, temperature dependence conductivity in the temperature range of 308–368 K and transport number measurements were employed to characterize this polymer electrolyte system. The conductivity of the (PEO+KHCO3 electrolyte was found to be about 3 times larger than that of pure PEO at room temperature. The transference data indicated that the charge transport in these polymer electrolyte systems is predominantly due to K+ ions. Using this polymer electrolyte an electrochemical cell with configuration K+/(PEO+KHCO3/(I2+C+electrolyte was fabricated and its discharge characteristics are studied. A number of other cell parameters associated with the cell were evaluated and are reported in this paper.
NOISE-INDUCED CHAOTIC MOTIONS IN HAMILTONIAN SYSTEMS WITH SLOW-VARYING PARAMETERS
王双连; 郭乙木; 甘春标
2001-01-01
This paper studies chaotic motions in quasi-integrable Hamiltonian systems with slow-varying parameters under both harmonic and noise excitations.Based on the dynamic theory and some assumptions of excited noises, an extended form of the stochastic Melnikov method is presented. Using this extended method, the homoclinic bifurcations and chaotic behavior of a nonlinear Hamiltonian system with weak feed-back control under both harmonic and Gaussian white noise excitations are analyzed in detail. It is shown that the addition of stochastic excitations can make the parameter threshold value for the occurrence of chaotic motions vary in a wider region. Therefore, chaotic motions may arise easily in the system. By the Monte-Carlo method, the numerical results for the time-history and the maximum Lyapunov exponents of an example system are finally given to illustrate that the presented method is effective.
Chaotic motion of the dynamical system under both additive and multiplicative noise excitations
Li Xiu-Chun; Xu Wei; Li Rui-Hong
2008-01-01
With both additive and multiplicative noise excitations,the effect on the chaotic behaviour of the dynamical system is investigated in this paper.The random Melnikov theorem with the mean-square criterion that applies to a type of dynamical systems is analysed in order to obtain the conditions for the possible occurrence of chaos.As an example,for the Duffing system,we deduce its concrete expression for the threshold of multiplicative noise amplitude for the rising of chaos,and by combining figures,we discuss the influences of the amplitude,intensity and frequency of both bounded noises on the dynamical behaviour of the Duffing system separately.Finally,numerical simulations are.
Experimental Investigation of Active Noise Controller for Internal Combustion Engine Exhaust System
Wu, Jian-Da; Chen, Chih-Keng; Lee, Chun-Ying; Lee, Tian-Hua
2002-10-01
Two active noise control (ANC) algorithms for internal combustion engine exhaust systems are developed and their performances are compared in various experiments. The first controller is based on the filtered-x least mean square (FXLMS) algorithm with feedback neutralization, while the second is a fixed controller with a gain-scheduled active control technique for broadband attenuation with thermal effects. Both control algorithms are implemented on a digital signal processing (DSP) platform. Experiments are carried out to evaluate the attenuation performance of the proposed active noise control systems for an engine exhaust system. The results of the experiments indicate that both the adaptive controller and the gain-scheduled controller effectively suppress the noise of engine exhaust systems. The experimental comparison and analysis of the proposed controllers are also described.
Common mode noise cancellation for electrically non-contact ECG measurement system on a chair.
Keun Kim, Ko; Kyu Lim, Yong; Suk Park, Kwang
2005-01-01
Electrically non-contact ECG measurement system on a chair can be applied to a number of various fields for continuous health monitoring in daily life. However, the body is floated electrically for this system due to the capacitive electrodes and the floated body is very sensitive to the external noises or motion artifacts which affect the measurement system as the common mode noise. In this paper, the Driven-Seat-Ground circuit similar to the Driven-Right-Leg circuit is proposed to reduce the common mode noise. The analysis of this equivalent circuit is performed and the output signal waveforms are compared between with Driven-Seat-Ground and with capacitive ground. As the results, the Driven-Seat-Ground circuit improves significantly the properties of the fully capacitive ECG measurement system as the negative feedback.
Evolution of Lotka-Volterra predator-prey systems under telegraph noise.
Auger, P; Du, N H; Hieu, N T
2009-10-01
In this paper we study a Lotka-Volterra predator-prey system with prey logistic growth under the telegraph noise. The telegraph noise switches at random two prey-predator models. The aim of this work is to determine the subset of omega-limit set of the system and show out the existence of a stationary distribution. We also focus on persistence of the predator and thus we look for conditions that allow persistence of the predator and prey community. We show that the asymptotic behaviour highly depends on the value of some constant lambda which is useful to make suitable predictions about the persistence of the system.
Effective drifts in dynamical systems with multiplicative noise: a review of recent progress
Volpe, Giovanni; Wehr, Jan
2016-05-01
Noisy dynamical models are employed to describe a wide range of phenomena. Since exact modeling of these phenomena requires access to their microscopic dynamics, whose time scales are typically much shorter than the observable time scales, there is often need to resort to effective mathematical models such as stochastic differential equations (SDEs). In particular, here we consider effective SDEs describing the behavior of systems in the limits when natural time scales become very small. In the presence of multiplicative noise (i.e. noise whose intensity depends upon the system’s state), an additional drift term, called noise-induced drift or effective drift, appears. The nature of this noise-induced drift has been recently the subject of a growing number of theoretical and experimental studies. Here, we provide an extensive review of the state of the art in this field. After an introduction, we discuss a minimal model of how multiplicative noise affects the evolution of a system. Next, we consider several case studies with a focus on recent experiments: the Brownian motion of a microscopic particle in thermal equilibrium with a heat bath in the presence of a diffusion gradient; the limiting behavior of a system driven by a colored noise modulated by a multiplicative feedback; and the behavior of an autonomous agent subject to sensorial delay in a noisy environment. This allows us to present the experimental results, as well as mathematical methods and numerical techniques, that can be employed to study a wide range of systems. At the end we give an application-oriented overview of future projects involving noise-induced drifts, including both theory and experiment.
Probabilistic density function method for nonlinear dynamical systems driven by colored noise.
Barajas-Solano, David A; Tartakovsky, Alexandre M
2016-05-01
We present a probability density function (PDF) method for a system of nonlinear stochastic ordinary differential equations driven by colored noise. The method provides an integrodifferential equation for the temporal evolution of the joint PDF of the system's state, which we close by means of a modified large-eddy-diffusivity (LED) closure. In contrast to the classical LED closure, the proposed closure accounts for advective transport of the PDF in the approximate temporal deconvolution of the integrodifferential equation. In addition, we introduce the generalized local linearization approximation for deriving a computable PDF equation in the form of a second-order partial differential equation. We demonstrate that the proposed closure and localization accurately describe the dynamics of the PDF in phase space for systems driven by noise with arbitrary autocorrelation time. We apply the proposed PDF method to analyze a set of Kramers equations driven by exponentially autocorrelated Gaussian colored noise to study nonlinear oscillators and the dynamics and stability of a power grid. Numerical experiments show the PDF method is accurate when the noise autocorrelation time is either much shorter or longer than the system's relaxation time, while the accuracy decreases as the ratio of the two timescales approaches unity. Similarly, the PDF method accuracy decreases with increasing standard deviation of the noise.
Phase noise analysis for OFDM systems based on hot-carrier effects in synchronization electronics
Herlekar, Sameer R.; Zhang, Chi; Wu, Hsiao-Chun; Srivastava, Ashok
2005-05-01
Phase noise may be regarded as the most severe cause of performance degradation in OFDM systems. Hot carriers (HCs), found in the CMOS synchronization circuits, are high-mobility charge carriers that degrade the MOSFET devices" performance by increasing the threshold voltage required to operate the MOSFETs. The HC effect manifests itself as the phase noise, which increases with the continued MOSFET operation and results in the performance degradation of the Voltage-Controlled Oscillator (VCO) built on the MOSFET. The HC effect is particularly evident in the short-channel MOSFET devices. The MOSFET instability will impact on the OFDM system performance. The relationship between the OFDM system performance and the hot carrier effect can be analyzed in terms of a crucial parameter, the MOSFET threshold voltage. In this paper, we derive a general phase noise model for OFDM systems based on the Hot-carrier effect and the corresponding drifted threshold voltage in differential ring oscillators. The expected OFDM performance degradation due to the hot carrier effect is provided through our simulations. We show that the OFDM BER performance evaluation using the existing phase noise models can be upto three orders of magnitude different from the results obtained by using our phase noise model.
Dimensioning BCH codes for coherent DQPSK systems with laser phase noise and cycle slips
Leong, Miu Yoong; Larsen, Knud J.; Jacobsen, Gunnar
2014-01-01
Forward error correction (FEC) plays a vital role in coherent optical systems employing multi-level modulation. However, much of coding theory assumes that additive white Gaussian noise (AWGN) is dominant, whereas coherent optical systems have significant phase noise (PN) in addition to AWGN. Thi...... approach for a target post-FEC BER of 10-5. Codes dimensioned with our bivariate binomial model meet the target within 0.2-dB signal-to-noise ratio....... these statistics to parameterize a bivariate binomial model that describes the distribution of bit errors. In this way, we relate pre-FEC statistics to post-FEC BER and BCH codes. Our method is applicable to pre-FEC BER around 10-3 and any post-FEC BER. Using numerical simulations, we evaluate the accuracy of our......Forward error correction (FEC) plays a vital role in coherent optical systems employing multi-level modulation. However, much of coding theory assumes that additive white Gaussian noise (AWGN) is dominant, whereas coherent optical systems have significant phase noise (PN) in addition to AWGN...
1992-11-01
Library Qantas Airways Limited Civil Aviation Authority Gas & Fuel Corporation of Vic., Manager Scientific Services Ampol Petroleum (Vic) Pty Ltd...Aircraft 3 2.3 Recording and Measurement System 5 2.4 Analysis Equipment 5 2.5 Test Procedure 5 3. RESULTS 7 3.1 Ambient Noise Levels in the S-70B-2 7...using spectral analysis techniques to determine the acoustic characteristics of this noise, b) measuring at-ear SPLs under the ALPHA helmet and
ON THE ANISOTROPIC NORM OF DISCRETE TIME STOCHASTIC SYSTEMS WITH STATE DEPENDENT NOISE
Isaac Yaesh
2013-01-01
Full Text Available The purpose of this paper is to determine conditions for the bound-edness of the anisotropic norm of discrete-time linear stochastic sys-tems with state dependent noise. It is proved that these conditions canbe expressed in terms of the feasibility of a specific system of matrixinequalities.
H∞ Control for Nonlinear Stochastic Systems with Time-Delay and Multiplicative Noise
Ming Gao
2015-01-01
Full Text Available This paper studies the infinite horizon H∞ control problem for a general class of nonlinear stochastic systems with time-delay and multiplicative noise. The exponential/asymptotic mean square H∞ control design of delayed nonlinear stochastic systems is presented by solving Hamilton-Jacobi inequalities. Two numerical examples are provided to show the effectiveness of the proposed design method.
A rapid prototyping system for broadband multichannel active noise and vibration control
Wesselink, Johan Marius
2009-01-01
The development system presented in this thesis consists of a highly integrated controller which can be used for different active noise and vibration control (ANVC) applications. The system consists of an embedded PC and an interfacing card that can offer up to 16 analog input and output channels. T
HAN Yin-Xia; LI Jing-Hui; ZHAO Ying-Kui; CHEN Shi-Gang
2005-01-01
In this paper, we study spatially periodic system with infinite globally coupled oscillators driven by temporal-spatial noise and subject to a constant force. The results show that the system exhibits the phenomena of the non-equilibrium phase transition, transport of particles, and the anomalous hysteresis cycle for the mean field and the probability current.
Electromagnetic Compatibility (EMC) and Noise Background Testing for Double Chooz PMT System
Cepero, J. R.; Encabo Fernandez, F. J.; Pepe, I.; Verdugo, A.
2009-05-21
The Double Chooz PMT system is a HV/signal splitter. In this report is presented an electromagnetic compatibility and background noise testing for the Double Chooz PMT system. It was possible to proceed the EMC testing on different grounding configurations of PMT splitter due to its special PCB design, endowed of jumping points and a metal box ground electrode. (Author)
Preparation and characterization of a new carbonaceous material for electrochemical systems
ZI JI LIN
2010-02-01
Full Text Available A new carbonaceous material was successfully prepared by the py-rolysis of scrap tire rubber at 600 °C under a nitrogen atmosphere. The physical characteristics of the prepared carbonaceous material were studied by scanning electron microscopy (SEM, X-ray powder diffraction (XRD and X-ray photoelectron spectroscopy (XPS. It was proved that the carbonaceous material had a disordered structure and spherical morphology with an average particle size about 100 nm. The prepared carbonaceous material was also used as electrodes in electrochemical systems to examine its electrochemical performances. It was demonstrated that it delivered a lithium insertion capacity of 658 mA h g-1 during the first cycle with a coulombic efficiency of 68 %. Cyclic voltammograms test results showed that a redox reaction occurred during the cycles. The chemical diffusion coefficient based on the impedance diagram was about 10-10 cm2 s-1. The pyrolytic carbonaceous material derived from scrap tire rubber is therefore considered to be a potential anode material in lithium secondary batteries or capacitors. Furthermore, it is advantageous for environmental protection.
Application of thermal electrochemical equation to metal-hydride half-cell system
LIU Kai-yu; HUANG Bai-yun; ZHANG Ping-min; HE Yue-hui; ZHOU Ke-chao; SU Geng
2006-01-01
Application of thermal electrochemical equation to metal-hydride half-cell system was investigated, and the influence of state of charge on the thermal electrochemical performance of hydrogen storage materials was studied. The results show that both the absolute value of the molar enthalpy change and the internal resistance of evolution hydrogen reaction are less than that of absorption hydrogen reaction at the same state of charge. The molar reaction enthalpy change of absorption and evolution of hydride electrode change contrarily with the enhancement of filling degree of hydrogen in hydride electrode. The relation curve of molar reaction enthalpy change to state of charge, both absorption and evolution hydrogen reaction, is close to a constant when the state of charge is 10%-60%, and during state of charge below 10% or state of charge above 60%, the molar reaction enthalpy change varies sharply. Meanwhile, the internal resistance of electrode reaction has an ascending trend with the enhancement on filling degree of hydrogen in hydride electrode in both absorption and evolution hydrogen reaction.
WANG Mei-jia; BAI Yu-bai; LI Tie-jin; YUAN Hang; JI Xiao-hui; LIU Zhao-yue; JIA Ruo-kun; WANG Lian-ying; LIU Yan-mei; MA Lan; LI Jing-hong
2003-01-01
A novel sensitive electrochemical immunoassay with colloidal gold as the antibody labeling tag and subsequent signal amplification by silver enhancement is described. Colloidal gold was treated by a light-sensitive silver enhancement system which made silver deposit on the surface of colloidal gold(form Au/Ag core-shell structure), followed by the release of the metallic silver atoms anchored on the antibody by oxidative dissolution of them in an acidic solution and the indirect determination of the dissolved Ag+ ions by anodic stripping voltammetry(ASV) at a carbon fiber microelectrode. The electrochemical signal is directly proportional to the amount of analyte(goat IgG) in the standard or a sample. The method was evaluated by means of a noncompetitive heterogeneous immunoassay of immunoglobulin G(IgG) with a concentration as low as 0.2 ng/mL. The high performance of the method is related to the sensitive ASV determination of silver(Ⅰ) at a carbon fiber microelectrode and to the release of a large number of Ag+ ions from each silver shell anchored on the analyte(goat IgG).
Natural flavonoids interact with dinitrobenzene system in aprotic media: an electrochemical probing.
Arshad, Nasima; Janjua, Naveed K; Khan, Athar Y; Yaqub, Azra; Burkholz, Torsten; Jacob, Claus
2012-03-01
Three structurally related natural flavonoids (FlOH), quercetin (Q), rutin (R) and morin (M), were investigated by cyclic voltammetry to probe their interactions with hazardous 1,4-dinitrobenzene (1,4-DNB) using a glassy carbon electrode. Scavenging of 1,4-DNB by FlOH was inferred from a positive shift in reduction potential, decrease in anodic peak current, and irreversible electrochemical behavior of 1,4-DNB on increasing the flavonoid concentration. The homogeneous bi-molecular rate constant (k2) was determined using the Nicholson-Shain equation and found to be higher for the dianion. Morin posed a comparatively higher k2 value for its interaction with the 1,4-DNB electrochemical system owing to its more acidic nature and least intramolecular hydrogen bonding. The cyclic voltammetric (CV) results were further supported by HyperchemPM3 quantum mechanical semi-empirical calculations, which point towards E(r)C(i) interactions between flavonoids and 1,4-DNB. The present investigation is biologically significant in terms of natural flavonoidal scavenging activity toward toxins such as dinitroaromatics.
Calle, Luz
1990-01-01
AC impedance measurements were performed to investigate the corrosion resistance of 18 alloys under conditions similar to the Space Transportation System (STS) launch environment. The alloys were: (1) zirconium 702; (2) Hastelloy C-22, C-276, C-4, and B-2; (3) Inconel 600 and 825; (4) Ferralium 255; (5) Inco Alloy G-3; (6) 20Cb-3; (7) SS 904L, 304LN, 316L, 317L, and 304L; (8) ES 2205; and (9) Monel 400. AC impedance data were gathered for each alloy at various immersion times in 3.55 percent NaCl-0.1N HCl. Polarization resistance values were obtained for the Nyguist plots at each immersion time using the EQUIVALENT CIRCUIT software package available with the 388 electrochemical impedance software. Hastelloy C-22 showed the highest overall values for polarization resistance while Monel 400 and Inconel 600 had the lowest overall values. There was good general correlation between the corrosion performance of the alloys at the beach corrosion testing site, and the expected rate of corrosion as predicted based on the polarization resistance values obtained. The data indicate that electrochemical impedance spectroscopy can be used to predict the corrosion performance of metal alloys.
Method and system to perform energy-extraction based active noise control
Kelkar, Atul (Inventor); Joshi, Suresh M. (Inventor)
2009-01-01
A method to provide active noise control to reduce noise and vibration in reverberant acoustic enclosures such as aircraft, vehicles, appliances, instruments, industrial equipment and the like is presented. A continuous-time multi-input multi-output (MIMO) state space mathematical model of the plant is obtained via analytical modeling and system identification. Compensation is designed to render the mathematical model passive in the sense of mathematical system theory. The compensated system is checked to ensure robustness of the passive property of the plant. The check ensures that the passivity is preserved if the mathematical model parameters are perturbed from nominal values. A passivity-based controller is designed and verified using numerical simulations and then tested. The controller is designed so that the resulting closed-loop response shows the desired noise reduction.
A New Subband Adaptive Filtering Algorithm for Sparse System Identification with Impulsive Noise
Young-Seok Choi
2014-01-01
Full Text Available This paper presents a novel subband adaptive filter (SAF for system identification where an impulse response is sparse and disturbed with an impulsive noise. Benefiting from the uses of l1-norm optimization and l0-norm penalty of the weight vector in the cost function, the proposed l0-norm sign SAF (l0-SSAF achieves both robustness against impulsive noise and remarkably improved convergence behavior more than the classical adaptive filters. Simulation results in the system identification scenario confirm that the proposed l0-norm SSAF is not only more robust but also faster and more accurate than its counterparts in the sparse system identification in the presence of impulsive noise.
A Modified Structure for Feed Forward Active Noise Control Systems With Improved Performa
P.Babu
2010-09-01
Full Text Available Several approaches have been introduced in literature for active noise control (ANC systems. SinceFxLMS algorithm appears to be the best choice as a controller filter, researchers tend to improveperformance of ANC systems by enhancing and modifying this algorithm. In this paper, the existingFxLMS algorithm is modified which provides a new structure for improving the noise reduction andconvergence rate. Here the proposed method uses two variable step sizes, one for control filter andanother for modelling filter. The control filter step size is varied based on the secondary path thresholdsignal l dˆ . The modelling filter step size is varied based on error signal f (n . It is shown that in theproposed method ANC system noise reduction rate and convergence rate are improved dynamically thanthe FxLMS variable step size methods. The computer simulations results indicate effectiveness of theproposed method.
Probabilistic density function method for nonlinear dynamical systems driven by colored noise
Barajas-Solano, David A.; Tartakovsky, Alexandre M.
2016-05-01
We present a probability density function (PDF) method for a system of nonlinear stochastic ordinary differential equations driven by colored noise. The method provides an integro-differential equation for the temporal evolution of the joint PDF of the system's state, which we close by means of a modified Large-Eddy-Diffusivity-type closure. Additionally, we introduce the generalized local linearization (LL) approximation for deriving a computable PDF equation in the form of the second-order partial differential equation (PDE). We demonstrate the proposed closure and localization accurately describe the dynamics of the PDF in phase space for systems driven by noise with arbitrary auto-correlation time. We apply the proposed PDF method to the analysis of a set of Kramers equations driven by exponentially auto-correlated Gaussian colored noise to study the dynamics and stability of a power grid.
Li, Henan; Tian, Yan; Qu, Youpeng; Qiu, Ye; Liu, Jia; Feng, Yujie
2017-01-01
A benthic microbial electrochemical systems (BMES) of 195 L (120 cm long, 25 cm wide and 65 cm height) was constructed for sediment organic removal. Sediment from a natural river (Ashi River) was used as test sediments in the present research. Three-dimensional anode (Tri-DSA) with honeycomb structure composed of carbon cloth and supporting skeleton was employed in this research for the first time. The results demonstrated that BMES performed good in organic-matter degradation and energy generation from sediment and could be considered for river sediments in situ restoration as novel method. Community analysis from the soil and anode using 16S rDNA gene sequencing showed that more electrogenic functional bacteria was accumulated in anode area when circuit connected than control system.
Caballero-Águila, R.; Hermoso-Carazo, A.; Linares-Pérez, J.
2015-02-01
In this paper, the optimal least-squares state estimation problem is addressed for a class of discrete-time multisensor linear stochastic systems with state transition and measurement random parameter matrices and correlated noises. It is assumed that at any sampling time, as a consequence of possible failures during the transmission process, one-step delays with different delay characteristics may occur randomly in the received measurements. The random delay phenomenon is modelled by using a different sequence of Bernoulli random variables in each sensor. The process noise and all the sensor measurement noises are one-step autocorrelated and different sensor noises are one-step cross-correlated. Also, the process noise and each sensor measurement noise are two-step cross-correlated. Based on the proposed model and using an innovation approach, the optimal linear filter is designed by a recursive algorithm which is very simple computationally and suitable for online applications. A numerical simulation is exploited to illustrate the feasibility of the proposed filtering algorithm.
Improvement of the noise figure of the CEBAF switched electrode electronics BPM system
Powers, Tom
1998-12-01
The Continuous Electron Beam Accelerator Facility (CEBAF) is a high-intensity continuous wave electron accelerator for nuclear physics located at Thomas Jefferson National Accelerator Facility. A beam energy of 4 GeV is achieved by recirculating the electron beam five times through two anti-parallel 400 MeV linacs. In the linacs, where there is recirculated beam, the BPM specifications must be met for beam intensities between 1 and 100 μA. In the transport lines the BPM specifications must be met for beam intensities between 100 nA and 200 μA. To avoid a complete redesign of the existing electronics, we investigated ways to improve the noise figure of the linac BPM switched-electrode electronics (SEE) so that they could be used in the transport lines. We found that the out-of-band noise contributed significantly to the overall system noise figure. This paper will focus on the source of the excessive out-of-band noise and how it was reduced. The development, commissioning and operational results of this low noise variant of the linac style SEE BPMs as well as techniques for determining the noise figure of the rf chain will also be presented.
Application of photothermal deflection spectroscopy to electrochemical interfaces
Rudnicki, J.D.; McLarnon, F.R.; Cairns, E.J.
1992-03-01
This dissertation discusses the theory and practice of Photothermal Deflection Spectroscopy (PDS, which is also known as probe beam deflection spectroscopy, PBDS, probe deflection technique, and mirage effect spectroscopy) with respect to electrochemical systems. Much of the discussion is also relevant to non-electrochemical systems. PDS can measure the optical absorption spectrum of interfaces and concentration gradients in the electrolyte adjacent to the electrode. These measurements can be made on a wide variety of electrode surfaces and can be performed under dynamic conditions. The first three chapters discuss the theory of the phenomena that can be detected by PDS, and the equipment used in a PDS system. A ``secondary gradient technique`` is proposed, which places the probe beam on the back of an electrode. The results of a numerical model yield a method for determining the offset of the probe beam from the electrode surface based on the frequency response of the PDS signal. The origin and control of noise in the PDS signal are discussed. A majority of the signal noise appears to be acoustic in origin. The electrochemical oxidation of platinum is used to demonstrate that PDS has sub-monolayer sensitivity necessary to study interfacial chemistry. The results allow us to propose a two-reaction oxidation mechanism: the platinum is electrochemically oxidized to form platinum dihydroxide and dehydrated by a non-electrochemical second-order reaction. The final chapter discusses the relation of PDS to similar and competing techniques, and considers possibilities for the future of the technique.
Required changes in emission standards for high-frequency noise in power systems
Lundmark, C.M.; Larsson, E.O.A. [Lulea Univ. of Technology, Skelleftea (Sweden); Bollen, M.H.J. [STRI AB, Ludvika (Sweden)
2006-07-01
This paper discusses some recent developments that make the existing standards on the emission of high-frequency noise in power systems due for reconsideration. It is shown that it is possible for an equipment to remain below the emission limits while at the same time the disturbance level increases beyond what was intended by the standard document. Further, the change from analog to digital communication and the use of communication via the power system, make that the permitted disturbance levels need to be reconsidered. This paper also contains an example of measured high-frequency noise and proposes a framework for re-coordination of emission and immunity levels. (Author)
Numerical Investigation of Noise Enhanced Stability Phenomenon in a Time-Delayed Metastable System
JIA Zheng-Lin
2008-01-01
@@ The transient properties of a time-delayed metastable system subjected to the additive white noise are investigated by means of the stochastic simulation method. The noise enhanced stability phenomenon (NES) can be observed in this system and the effect of the delay time on the NES shows a critical behaviour, i.e., there is a critical value of the delay time Tc ≈ 1, above which the time delay enhances the NES effect with the delay time increasing and below which the time delay weakens the NES effect as the delay time increases.
Simulation Model of the ANC System for Noise Reduction in the Real Ambient
STOJANOVIC, V. O.
2013-08-01
Full Text Available The simulation model of ANC system for noise reduction caused by rotating machines in a room was described in the first part of this paper. This simulation model was presented in an acoustic-electrical diagram. The detailed mathematical analysis of the adaptive algorithm was performed. The second part of the paper presents the simulation results of the application of the ANC system for the noise reduction of fans in a room intended for a classroom. Simulation was performed for sine and real aroused signal. The results are presented both numerically and graphically and the comparative analysis was also done.
Signal and noise analysis of a-Si:H radiation detector-amplifier system
Cho, Gyuseong.
1992-03-01
Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was {approximately}400 MHz and the noise charge {approximately}1000 electrons at a 1 {mu}sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of {approximately}0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.
Covert communications using random noise signals: overall system simulation and modulation analysis
Chuang, Jack; Narayanan, Ram M.
2005-06-01
In military communications, there exist numerous potential threats to message security. Ultra-wideband (UWB) signals provide secure communications because they cannot, in general, be detected using conventional receivers and they can be made relatively immune from jamming. The security of an UWB signal can be further improved by mixing it with random noise. By using a random noise signal, the user can conceal the message signal within the noise waveform and thwart detection by hostile forces. This paper describes a novel spread spectrum technique that can be used for secure and covert communications. The technique is based on the use of heterodyne correlation techniques to inject coherence in a random noise signal. The modulated signal to be transmitted containing the coherent carrier is mixed with a sample of an ultrawideband random noise signal. The frequency range of the ultra-wideband noise signal is appropriately chosen so that the lower sideband of the mixing process falls over the same frequency range. Both the frequency-converted noise-like signal and the original random noise signal are simultaneously transmitted on orthogonally polarized channels through a dual-polarized transmitting antenna. The receiver consists of a similar dual-polarized antenna that simultaneously receives the two orthogonally polarized transmitted signals, amplifies each in a minimum phase limiting amplifier, and mixes these signals in a double sideband up-converter. The upper sideband of the mixing process recovers the modulated signal, which can then be demodulated. The advantage of this technique lies in the relative immunity of the random noise-like un-polarized transmit signal from detection and jamming. Since the transmit signal "appears" totally un-polarized and noise-like, linearly polarized receivers are unable to identify, decode, or otherwise extract useful information from the signal. The system is immune from interference caused by high power linearly polarized signal
Noise management to achieve superiority in quantum information systems
Nemoto, Kae; Devitt, Simon; Munro, William J.
2017-06-01
Quantum information systems are expected to exhibit superiority compared with their classical counterparts. This superiority arises from the quantum coherences present in these quantum systems, which are obviously absent in classical ones. To exploit such quantum coherences, it is essential to control the phase information in the quantum state. The phase is analogue in nature, rather than binary. This makes quantum information technology fundamentally different from our classical digital information technology. In this paper, we analyse error sources and illustrate how these errors must be managed for the system to achieve the required fidelity and a quantum superiority. This article is part of the themed issue 'Quantum technology for the 21st century'.
Jianxin Feng
2014-01-01
Full Text Available The recursive estimation problem is studied for a class of uncertain dynamical systems with different delay rates sensor network and autocorrelated process noises. The process noises are assumed to be autocorrelated across time and the autocorrelation property is described by the covariances between different time instants. The system model under consideration is subject to multiplicative noises or stochastic uncertainties. The sensor delay phenomenon occurs in a random way and each sensor in the sensor network has an individual delay rate which is characterized by a binary switching sequence obeying a conditional probability distribution. By using the orthogonal projection theorem and an innovation analysis approach, the desired recursive robust estimators including recursive robust filter, predictor, and smoother are obtained. Simulation results are provided to demonstrate the effectiveness of the proposed approaches.
Bashkirtseva, Irina; Ryashko, Lev; Ryazanova, Tatyana
2017-09-01
A problem of the analysis of the noise-induced extinction in multidimensional population systems is considered. For the investigation of conditions of the extinction caused by random disturbances, a new approach based on the stochastic sensitivity function technique and confidence domains is suggested, and applied to tritrophic population model of interacting prey, predator and top predator. This approach allows us to analyze constructively the probabilistic mechanisms of the transition to the noise-induced extinction from both equilibrium and oscillatory regimes of coexistence. In this analysis, a method of principal directions for the reducing of the dimension of confidence domains is suggested. In the dispersion of random states, the principal subspace is defined by the ratio of eigenvalues of the stochastic sensitivity matrix. A detailed analysis of two scenarios of the noise-induced extinction in dependence on parameters of considered tritrophic system is carried out.
Noise-induced memory in extended excitable systems
Chialvo, D R; Magnasco, M O; Chialvo, Dante R.; Cecchi, Guillermo A.; Magnasco, Marcelo O.
1999-01-01
We describe a form of memory exhibited by extended excitable systems driven by stochastic fluctuations. Under such conditions, the system self-organizes into a state characterized by power-law correlations thus retaining long-term memory of previous states. The exponents are robust and model-independent. We discuss novel implications of these results for the functioning of cortical neurons as well as for networks of neurons.
O. Sharifi-Tehrani
2012-10-01
Full Text Available In this paper, an active noise control system for denoising the intercommunication signal of an airplane cockpit isproposed. Noise sources such as engines degrade the quality of the intercommunication signal, especially in the caseof the pilot and copilot headsets. A two-microphone active adaptive noise controller is designed by using an adaptiveFIR filter in an active structure. The designed system is simulated and also implemented in real environment usingreal speech signals, periodic noise and AWGN noise. Also, an FPGA-based hardware implementation utilizing a novelmethod is provided. The whole design is considered an FPGA hardware core with low resource utilizations which issuitable for HW/SW codesign and System-on-Programmable-Chip (SoPC applications. The codes have been writtenby using the VHDL93 hardware description language, the XilKernel embedded operating system and a finite statemachine. The obtained results showed competent functionality and performance of the proposed system. This ICSnoise removal architecture can be used on any cargo, civil or fighter platform (such as C-130, IR-AN 140 and F5-Fand also in radar and electronic warfare (EW systems (for clutter/interference compensation with minimum hardwareor software changes.
Electrochemical nitridation of metal surfaces
Wang, Heli; Turner, John A.
2015-06-30
Electrochemical nitridation of metals and the produced metals are disclosed. An exemplary method of electrochemical nitridation of metals comprises providing an electrochemical solution at low temperature. The method also comprises providing a three-electrode potentiostat system. The method also comprises stabilizing the three-electrode potentiostat system at open circuit potential. The method also comprises applying a cathodic potential to a metal.
Contento, Nicholas M.
Chemical analysis is being performed in devices operated at ever decreasing length scales in order to harness the fundamental benefits of micro and nanoscale phenomena while minimizing operating footprint and sample size. The advantages of moving traditional sample or chemical processing steps (e.g. separation, detection, and reaction) into micro- and nanofluidic devices have been demonstrated, and they arise from the relatively rapid rates of heat and mass transport at small length scales. The use of electrochemical methods in micro/nanoscale systems to control and improve these processes holds great promise. Unfortunately, much is still not understood about the coupling of multiple electrode driven processes in a confined environment nor about the fundamental changes in device performance that occur as geometries approach the nanoscale regime. At the nanoscale a significant fraction of the sample volume is in close contact with the device surface, i.e. most of the sample is contained within electronic or diffusion layers associated with surface charge or surface reactions, respectively. The work presented in this thesis aims to understand some fundamental different behaviors observed in micro/nanofluidic structures, particularly those containing one or more embedded, metallic electrode structures. First, a quantitative method is devised to describe the impact of electric fields on electrochemistry in multi-electrode micro/nanofluidic systems. Next the chemical manipulation of small volumes (≤ 10-13 L) in micro/nanofluidic structures is explored by creating regions of high pH and high dissolved gas (H 2) concentration through the electrolysis of H2O. Massively parallel arrays of nanochannel electrodes, or embedded annular nanoband electrodes (EANEs), are then studied with a focus on achieving enhanced signals due to coupled electrokinetic and electrochemical effects. In EANE devices, electroosmotic flow results from the electric field generated between the
The accurate use of impedance analysis for the study of microbial electrochemical systems.
Dominguez-Benetton, Xochitl; Sevda, Surajbhan; Vanbroekhoven, Karolien; Pant, Deepak
2012-11-07
The present critical review aims to portray the principles and theoretical foundations that have been used for the application of electrochemical impedance spectroscopy (EIS) to study electron-transfer mechanisms, mass transfer phenomena and distribution of the heterogeneous properties of microbial electrochemical systems (MXCs). Over the past eight years, the application of this method has allowed major breakthroughs, especially in the field of microbial fuel cells (MFCs); however, it is still most widely extended only to the calculation of internal resistances. The use and interpretation of EIS should greatly improve since the intrinsic knowledge of this field, and efforts and current trends in this field have already allowed its understanding based on rather meaningful physical properties and not only on fitting electrical analogues. From this perspective, the use, analysis and interpretation of EIS applied to the study of MXCs are critically examined. Together with the revision of more than 150 articles directly devoted to this topic, two examples of the correct and improved analysis of EIS data are extensively presented. The first one focuses on the use of graphical methods for improving EIS analysis and the other one concentrates on the elucidation of the constant phase element (CPE) parameters. CPEs have been introduced in equivalent circuit models, sometimes without solid justification or analysis; the effective capacitance has been obtained from CPE parameters, following an unsuitable theory for the case of microbial-electrochemical interfaces. The use of CPE is reviewed in terms of meaningful physical parameters, such as biofilm thickness. The use of a finite-diffusion element is reviewed throughout estimation of accurate values for obtaining the dimensionless numbers, Schmidt and Sherwood, in the context of a dioxygen-reducing-biocathode, under different flow-rate conditions. The use and analysis of EIS in this context are still emerging, but because of
Barranco, E. (Dept. de Quimica Organica y Analitica, Facultad de C. Quimicas, Univ. Complutense, Madrid (Spain)); Gonzalez, A. (Dept. de Quimica Organica y Analitica, Facultad de C. Quimicas, Univ. Complutense, Madrid (Spain)); Martin, N. (Dept. de Quimica Organica y Analitica, Facultad de C. Quimicas, Univ. Complutense, Madrid (Spain)); Pingarron, J.M. (Dept. de Quimica Organica y Analitica, Facultad de C. Quimicas, Univ. Complutense, Madrid (Spain)); Segura, J.L. (Dept. de Quimica Organica y Analitica, Facultad de C. Quimicas, Univ. Complutense, Madrid (Spain)); Seoane, C. (Dept. de Quimica Organica y Analitica, Facultad de C. Quimicas, Univ. Complutense, Madrid (Spain)); Cruz, P. de la (Dept. de Quimica Organica, Inorganica y Bioquimica, Facultad de C. Quimicas, Univ. de Castilla-La Mancha, Toledo (Spain)); Langa, F. (Dept. de Quimica Organica, Inorganica y Bioquimica, Facultad de C. Quimicas, Univ. de Castilla-La Mancha, Toledo (Spain))
1993-03-29
The synthesis of novel [pi]-extended TCNQ and DCNQI derivatives from the corresponding 1,4-anthraquinones is described. The cyclic voltammetric data reveal that both TCNQ-type and DCNQI-type acceptors present two one-electron reduction waves to the corresponding anion-radical and dianion. These novel 2,3-fused TCNQ and DCNQI [pi]-extended systems are, according to the electrochemical values, better acceptors than the previously reported 2,3-5,6-fused TCNQ and DCNQI molecules. A good linear correlation between the first reduction potential of the substituted DCNQI-type derivatives versus the Hammett's [sigma][sub 3] constant has been found. (orig.)
Development of solid supports for electrochemical study of biomimetic membrane systems
Mech-Dorosz, Agnieszka
recording of a steady-state photocurrent while only a transient photocurrent peak was recorded on the polyelectrolyte cushion without a PES membrane. This PhD thesis also comprises the design and fabrication process of a modular microfluidic system with automated fluid delivery (micropumps and valves...... with reconstituted membrane spanning proteins, are attractive tools. However, BLMs suffer from intrinsic fragility, therefore, requiring techniques to increase their robustness and stability. This PhD thesis presents strategies to construct solid supports for electrochemical studies of two biomimetic membrane...... transporter valinomycin. The presented work also includes a comprehensive EIS analysis and cryological scanning electron microscopic (cryo-SEM) imaging of hydrogels formulated in various molar ratios (1:100; 1:200; 1:400) of the cross-linker poly(ethylene glycol)dimethacrylate (PEGDMA) and 2-hydroxyethylene...
The reversibility of the vitamin C redox system: electrochemical reasons and biological aspects.
Sapper, H; Kang, S O; Paul, H H; Lohmann, W
1982-10-01
The biological efficacy of vitamin C depends on its redox abilities as given by the relations between ascorbic acid, semidehydroascorbic acid, and dehydroascorbic acid. It is shown by means of proton magnetic resonance spectroscopy that the enzymatic (by ascorbate oxidase) as well as non-enzymatic (by iodine) oxidation of ascorbic acid is, in principle, reversible despite the hydration and structural changes during the formation of dehydroascorbic acid. The strong redox activity of semidehydroascorbic acid which results in a fast disproportionation to ascorbic acid and dehydroascorbic acid is inferred from an inversion of the electrochemical potentials of the vitamin C redox system. The capacity of this is maintained by a fast reduction of dehydroascorbic acid e.g. by reduced glutathione, preventing its delactonization and further degradation.
Development of electrochemical impedance spectroscopy based sensing system for DEHP detection
Zia, Asif I.
2011-11-01
This research work presents a real time and non invasive technique to detect Di(2-ethylhexyl) phthalate (DEHP)content in purified water and quantify its concentration by Electrochemical Impedance Spectroscopy(E.I.S.). Planar Inter-digital capacitive sensor is employed to evaluate conductivity, permeability and dielectric properties of material under test. This sensor, consisting of inter-digitated microelectrodes, is fabricated on silicon substrate using thin-film Microelectromechanical system (MEMS) based semiconductor device fabrication technology. Impedance spectrums are obtained with various concentrations of DEHP in purified water by using an electric circuit in order to extract sample conductance. Relationship of sample conductance with DEHP concentration is studied in this research work which enables us to show the ability of E.I.S. to detect DEHP concentration in water and hence can be applied in water treatment process for contamination quantification. © 2011 IEEE.
Tesfalidet, Solomon; Geladi, Paul; Shimizu, Kenichi; Lindholm-Sethson, Britta
2016-03-31
Methotrexate (MTX), a common pharmaceutical drug in cancer therapy and treatment of rheumatic diseases, is known to cause severe adverse side effects at high dose. As the side effect may be life threatening, there is an urgent need for a continuous, bed-side monitoring of the nominal MTX serum level in a patient while the chemical is being administered. This article describes a detection of MTX using a flow system that consists two modified gold electrodes. Interaction of MTX with the antibodies fixed on the electrode surface is detected by electrochemical impedance spectroscopy and evaluated using singular value decomposition (SVD). The key finding of this work is that the change in the electrode capacitance is found to be quantitative with respect to the concentration of MTX. Moreover a calibration curve constructed using the principal component regression method has a linear range of six orders of magnitude and a detection limit of 1.65 × 10(-10) M.
Testing for chaos in deterministic systems with noise
Gottwald, Georg A.; Melbourne, Ian
2005-12-01
Recently, we introduced a new test for distinguishing regular from chaotic dynamics in deterministic dynamical systems and argued that the test had certain advantages over the traditional test for chaos using the maximal Lyapunov exponent. In this paper, we investigate the capability of the test to cope with moderate amounts of noisy data. Comparisons are made between an improved version of our test and both the “tangent space method” and “direct method” for computing the maximal Lyapunov exponent. The evidence of numerical experiments, ranging from the logistic map to an eight-dimensional Lorenz system of differential equations (the Lorenz 96 system), suggests that our method is superior to tangent space methods and that it compares very favourably with direct methods.
Noise management to achieve superiority in quantum information systems.
Nemoto, Kae; Devitt, Simon; Munro, William J
2017-08-06
Quantum information systems are expected to exhibit superiority compared with their classical counterparts. This superiority arises from the quantum coherences present in these quantum systems, which are obviously absent in classical ones. To exploit such quantum coherences, it is essential to control the phase information in the quantum state. The phase is analogue in nature, rather than binary. This makes quantum information technology fundamentally different from our classical digital information technology. In this paper, we analyse error sources and illustrate how these errors must be managed for the system to achieve the required fidelity and a quantum superiority.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).
Research on Aircraft Noise Evaluation System%飞机噪声评价体系研究
沈颖; 谢实海; 陈荣生
2000-01-01
The evaluation system of aircraft noise and environment noise should be integrated,because aircraft noise belongs to environment noise.At the same time,there should be some difference in the evaluation system of aircraft noise.For solving this contradiction,this article puts forward a new evaluation system of aircraft noise.This new system unifies the evaluation of aircraft noise and other environment noise effectively,and adds a new evaluation index single-event noise exposure level.The system not only considers the characteristics of aircraft noise,which is different from other traffic noise,but also adds aircraft noise to other traffic noise,which can reflect sound environment around airport really.This system has practical worthiness and theory significance.%飞机噪声的共性决定其评价体系应于环境噪声评价体系统一，而飞机噪声的个性决定其评价方法必须有别于一般环境噪声评价.本文通过对飞机噪声的共性与个性的分析，建立了一种新的飞机噪声评价体系，它不仅考虑到飞机噪声不同于其他交通噪声的特点，而且有效地统一了飞机噪声与城市区域环境噪声的评价体系.新体系可以将机场周围飞机噪声与其他交通噪声叠加，真实地反映机场周围声环境，具有一定的实用价值和理论指导意义.
Sun, Yahui; Hong, Ling; Jiang, Jun; Li, Zigang
This paper proposes an efficient but simple method to determine the approximate stationary probability distribution around periodic attractors of nonautonomous nonlinear systems under multiple time-dependent parametric noises and estimate the critical noise intensity for noise-induced explosive bifurcations under a given confidence probability. After adopting a stroboscopic map constructed by a method with higher accuracy and efficiency, nonautonomous dynamical systems around periodic attractors are transformed into mapping ones. Then the mean-square analysis method of discrete systems is used to derive the stochastic sensitivity function. Based on the confidence ellipses of stochastic attractors and the global structure of deterministic nonlinear systems, the critical noise intensity of noise-induced explosive bifurcations under a given confidence probability is estimated. A Mathieu-Duffing oscillator under both multiplicative and additive noises is studied to show the validity of the proposed method.
H. Ashassi-Sorkhabi
2016-11-01
Full Text Available Epoxy–ZnO nanocomposite coatings have been developed for corrosion protection of steel. Structural characterization of the prepared nanocomposites was performed using scanning electron microscopy (SEM. The anti-corrosive properties of the coatings were evaluated by electrochemical noise (EN. On the basis of the EN results in both time and frequency domains, the nanocomposite material with low ZnO concentration (0.1% wt.% was found to be much superior in corrosion protection when tested in aqueous NaCl electrolyte. Finally, EIS measurements were carried out and the data fitted with suitable equivalent circuit. Resistance parameters obtained by both techniques were found to be in relatively good agreement.
A dynamic auditory-cognitive system supports speech-in-noise perception in older adults.
Anderson, Samira; White-Schwoch, Travis; Parbery-Clark, Alexandra; Kraus, Nina
2013-06-01
Understanding speech in noise is one of the most complex activities encountered in everyday life, relying on peripheral hearing, central auditory processing, and cognition. These abilities decline with age, and so older adults are often frustrated by a reduced ability to communicate effectively in noisy environments. Many studies have examined these factors independently; in the last decade, however, the idea of an auditory-cognitive system has emerged, recognizing the need to consider the processing of complex sounds in the context of dynamic neural circuits. Here, we used structural equation modeling to evaluate the interacting contributions of peripheral hearing, central processing, cognitive ability, and life experiences to understanding speech in noise. We recruited 120 older adults (ages 55-79) and evaluated their peripheral hearing status, cognitive skills, and central processing. We also collected demographic measures of life experiences, such as physical activity, intellectual engagement, and musical training. In our model, central processing and cognitive function predicted a significant proportion of variance in the ability to understand speech in noise. To a lesser extent, life experience predicted hearing-in-noise ability through modulation of brainstem function. Peripheral hearing levels did not significantly contribute to the model. Previous musical experience modulated the relative contributions of cognitive ability and lifestyle factors to hearing in noise. Our models demonstrate the complex interactions required to hear in noise and the importance of targeting cognitive function, lifestyle, and central auditory processing in the management of individuals who are having difficulty hearing in noise. Copyright © 2013 Elsevier B.V. All rights reserved.
Ashwin, Peter; Vitolo, Renato; Cox, Peter
2011-01-01
Tipping points associated with bifurcations (B-tipping) or induced by noise (N-tipping) are recognized mechanisms that may potentially lead to sudden climate change. We focus here a novel class of tipping points, where a sufficiently rapid change to an input or parameter of a system may cause the system to "tip" or move away from a branch of attractors. Such rate-induced tipping, or {\\em R-tipping}, need not be associated with either bifurcations or noise. We present an example exhibiting all three types of tipping in a simple global energy balance model of the climate system, illustrating the possibility of dangerous rates of change even in the absence of noise and of bifurcations in the underlying quasistatic system.
Further results on complete synchronization for noise-perturbed chaotic systems
Zhou, Jie; Chen, Zhang
2008-08-01
In this Letter, a class of general systems which covers several famous chaotic systems is studied in complete synchronization with noise perturbation. Special nonlinear coupling techniques as well as LaSalle-type invariance principle of stochastic differential equations are employed to deduce our sufficient conditions for complete synchronization without involving the boundedness of chaotic systems. Furthermore, the correlative numerical simulations are given to illustrate the effectiveness of our theoretic results.
Further results on complete synchronization for noise-perturbed chaotic systems
Zhou Jie [Research Center and Laboratory of Mathematics for Nonlinear Science, School of Mathematical Sciences, Fudan University, Shanghai 200433 (China)], E-mail: 031018020@fudan.edu.cn; Chen Zhang [School of Mathematics, Shandong University, Jinan 250100 (China)], E-mail: chenzhangcz@163.com
2008-08-11
In this Letter, a class of general systems which covers several famous chaotic systems is studied in complete synchronization with noise perturbation. Special nonlinear coupling techniques as well as LaSalle-type invariance principle of stochastic differential equations are employed to deduce our sufficient conditions for complete synchronization without involving the boundedness of chaotic systems. Furthermore, the correlative numerical simulations are given to illustrate the effectiveness of our theoretic results.
NOISE AND HYSTERESIS IN CHARGED STRIPE, CHECKERBOARD, AND CLUMP FORMING SYSTEMS
Reichhardt, Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reichhardt, Cynthia J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bishop, Alan R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2007-05-07
We numerically examine noise fluctuations and hysteresis phenomena in charged systems that form stripe, labyrinth or clump patterns. It is believed that charge inhomogeneities of this type arise in two-dimensional (2D) quantum hall systems and in electron crystal structures in high temperature superconductors, while related patterns appear in manganites and type-I superconductors. Recent noise and transport experiments in twodimensional electron gases and high temperature superconducting samples revealed both 1/ f^{α}. noise signatures and hysteretic phenomena. Using numerical simulations we show that 1/ f^{α}. noise fluctuations and hysteresis are generic features that occur in charge systems which undergo a type of phase separation that results in stripes, clumps, checkerboards, or other inhomogeneous patterns. We find that these systems exhibit 1/ f^{α}. fluctuations with 1.2 < α < 1.8, rather than simple 1/ f or 1/ f ^{2} fluctuations. We also propose that the 2D metal insulator transition may be associated with a clump electron glass phase rather than a Wigner glass phase.