WorldWideScience

Sample records for high common-mode noise

  1. Common mode noise modeling and its suppression in ultra-high efficiency full bridge boost converter

    DEFF Research Database (Denmark)

    Makda, Ishtiyaq Ahmed; Nymand, Morten; Madawala, Udaya

    2013-01-01

    In this paper, common mode noise modeling of low-voltage high-current isolated full bridge boost dc-dc converters intended for fuel cell application is presented. Due to the tightly coupled primary and secondary windings of the transformer, such converter has inherently large capacitive coupling...... between input and output which is normally associated with high common mode noise generation. In this work, common mode noise sources in the converter are identified, and a common mode noise model is developed. Based on the established noise model, a practical CM filter is designed to comply...... with the CISPR-A requirements. Finally, a 3kW dc-dc converter including filters has been built and tested to verify the theoretical model. Experimental results confirm the theoretical analysis of the converter....

  2. Common mode noise rejection properties of amplitude and phase noise in a heterodyne interferometer

    CERN Document Server

    Hechenblaikner, Gerald

    2013-01-01

    High precision metrology systems based on heterodyne interferometry can measure position and attitude of objects to accuracies of picometer and nanorad, respectively. A frequently found feature of the general system design is the subtraction of a reference phase from the phase of the position interferometer, which suppresses low frequency common mode amplitude and phase fluctuations occurring in volatile optical path sections shared by both, the position and reference interferometer. Spectral components of the noise at frequencies around or higher than the heterodyne frequency, however, are generally transmitted into the measurement band and may limit the measurement accuracy. Detailed analytical calculations complemented with Monte Carlo simulations show that high frequency noise components may also be entirely suppressed, depending on the relative difference of measurement and reference phase, which may be exploited by corresponding design provisions. Whilst these results are applicable to any heterodyne in...

  3. Common mode noise rejection properties of amplitude and phase noise in a heterodyne interferometer.

    Science.gov (United States)

    Hechenblaikner, Gerald

    2013-05-01

    High precision metrology systems based on heterodyne interferometry can measure the position and attitude of objects to accuracies of picometer and nanorad, respectively. A frequently found feature of the general system design is the subtraction of a reference phase from the phase of the position interferometer, which suppresses low frequency common mode amplitude and phase fluctuations occurring in volatile optical path sections shared by both the position and reference interferometer. Spectral components of the noise at frequencies around or higher than the heterodyne frequency, however, are generally transmitted into the measurement band and may limit the measurement accuracy. Detailed analytical calculations complemented with Monte Carlo simulations show that high frequency noise components may also be entirely suppressed, depending on the relative difference of measurement and reference phase, which may be exploited by corresponding design provisions. While these results are applicable to any heterodyne interferometer with certain design characteristics, specific calculations and related discussions are given for the example of the optical metrology system of the LISA Pathfinder mission to space.

  4. Current barriers to confine high frequency common mode currents

    NARCIS (Netherlands)

    Moonen, Dominicus Johannes Guilielmus; Buesink, Frederik Johannes Karel; Leferink, Frank Bernardus Johannes

    2016-01-01

    A commercially produced three phase power line filter is submitted to a Current Barrier (CB) Electro-Magnetic Compatibility (EMC) zoning strategy as an attempt to confine high frequency common mode currents. The intent of the paper is not to show how to build a ’perfect’ filter, since this is known.

  5. Common-mode noise analysis, modeling and filter design for a phase-shifted full-bridge forward converter

    DEFF Research Database (Denmark)

    Makda, Ishtiyaq Ahmed; Nymand, Morten

    2015-01-01

    This paper presents the common-mode noise analysis and modeling of a phase-shifted full-bridge forward converter. The common-mode noise source due to a transformer inter-winding capacitance is considered for the case of study. The generated common-mode noise voltage-source in a converter...... is analytically determined, which then leads to a common-mode noise modeling of a phase-shifted converter. Using a proposed model, common-mode noise-current harmonics are calculated and a fully analytical filter design procedure is presented to comply with the CISPR-11 standard. Finally, a prototype phase......-shifted forward converter is built to verify the theoretical analysis. This study shows that the primary-to-secondary transformer winding capacitance creates a very significant amount of common-mode noise current in a phase-shifted forward converter....

  6. Common mode noise cancellation for electrically non-contact ECG measurement system on a chair.

    Science.gov (United States)

    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.

  7. Micropower non-contact EEG electrode with active common-mode noise suppression and input capacitance cancellation.

    Science.gov (United States)

    Chi, Yu M; Cauwenberghs, Gert

    2009-01-01

    A non-contact EEG electrode with input capacitance neutralization and common-mode noise suppression circuits is presented. The coin sized sensor capacitively couples to the scalp without direct contact to the skin. To minimize the effect of signal attenuation and channel gain mismatch, the input capacitance of each sensor is actively neutralized using positive feedback and bootstrapping. Common-mode suppression is achieved through a single conductive sheet to establish a common mode reference. Each sensor electrode provides a differential gain of 60 dB. Signals are transmitted in a digital serial daisy-chain directly from a local 16-bit ADC, minimizing the number of wires required to establish a high density EEG sensor network. The micropower electrode consumes only 600 microW from a single 3.3 V supply.

  8. Electromagnetic noise in electric circuits: Ringing and resonance phenomena in the common mode

    Directory of Open Access Journals (Sweden)

    Shuji Kitora

    2014-11-01

    Full Text Available It is generally believed that electromagnetic noise originates from the coupling of electric signals in a circuit with electric signals in surrounding materials in the environment. However, the noise phenomenon had not been quantified until now. In order to study the phenomenon of noise, we considered a standard circuit (two transmission lines, to which an additional transmission line was introduced in order to explicitly take into account the effect of conductors in the environment. We performed calculations using a newly developed multiconductor transmission-line theory for the resulting three-line circuit in order to determine the magnitude of the coupling between the circuit and the conductors in the environment under various conditions. We observed ringing and resonance phenomena in the common mode, which influenced the performance of the normal mode as electromagnetic noise. Our findings were confirmed by recent experiments in which conductor lines were arranged in various ways using a printed circuit board (PCB. The ordinary usage of electricity in the standard electric circuit was found to be worst in exciting the common mode noise.

  9. Nanocrystalline core material for high-performance common mode inductors

    NARCIS (Netherlands)

    Roc'h, Anne; Leferink, Frank

    2012-01-01

    Modern power electronic semiconductors are switching very fast to reduce heat dissipation. Due to parasitic capacitances in the system, for instance, in a motor driven by an adjustable speed electrical power drive system, common mode currents are developed creating electromagnetic interference. The

  10. Nanocrystalline core material for high-performance common mode inductors

    NARCIS (Netherlands)

    Roc'h, A.; Leferink, Frank Bernardus Johannes

    Modern power electronic semiconductors are switching very fast to reduce heat dissipation. Due to parasitic capacitances in the system, for instance, in a motor driven by an adjustable speed electrical power drive system, common mode currents are developed creating electromagnetic interference. The

  11. Common mode noise in three-level DC-DC converters

    CSIR Research Space (South Africa)

    Grobler, Inus

    2009-09-01

    Full Text Available for accurate conducted EMI simulation purposes, such as SABER® is inaccessible to the general designer due to cost. The buck converter is shown as an example. Comparison is made between common mode currents in a standard two-level converter and also three...

  12. ANALYSIS AND MITIGATION OF COMMON MODE AND DIFFERENTIAL MODE NOISE ON BOOST CONVERTERS

    Directory of Open Access Journals (Sweden)

    C.Krishna Kumar,

    2010-09-01

    Full Text Available This paper is about the study and analysis on the effects of snubber circuits such as RLD, RCD and mixed (RLD+RCD over the conducted ELECTROMAGNETIC INTERFERENCE on high frequency power MOSFET. In this paper for various duty cycles separation of conducted EMI is done with the help of LISN circuit. The analysis is done for various duty cycles as 0.5, 0.55 and 0.6 for a switching frequency of 50 KHz using ORCAD PSPICE software. The simulated results are then compared with respect to their duty cycle.

  13. Fabrication of Compact Microstrip Line-Based Balun-Bandpass Filter with High Common-Mode Suppression

    Directory of Open Access Journals (Sweden)

    Chia-Mao Chen

    2014-01-01

    Full Text Available A new type of balun-bandpass filter was proposed based on the traditional coupled-line theory and folded open-loop ring resonators (OLRRs configuration. For that, a new device with both filter-type and balun-type characteristics was investigated and fabricated. Both magnetic and electric coupling structures were implemented to provide high performance balun-bandpass responses. The fabricated balun-bandpass filters had a wide bandwidth more than 200 MHz and a low insertion loss less than 2.51 dB at a center frequency of 2.6 GHz. The differences between the two outputs were below 0.4 dB in magnitude and within 180 ± 7° in phase. Also, the balun-bandpass filter presented an excellent common-mode rejection ratio over 25 dB in the passband. An advanced design methodology had been adopted based on EM simulation for making these designed parameters of OLRRs, microstrip lines, and open stubs. The measured frequency responses agreed well with simulated ones.

  14. Reduction of Common-Mode Conducted Noise Emissions in PWM Inverter-fed AC Motor Drive Systems using Optimized Passive EMI Filter

    Science.gov (United States)

    Jettanasen, C.; Ngaopitakkul, A.

    2010-10-01

    Conducted electromagnetic interference (EMI) generated by PWM inverter-fed induction motor drive systems, which are currently widely used in many industrial and/or avionic applications, causes severe parasitic current problems, especially at high frequencies (HF). These restrict power electronic drive's evolution. In order to reduce or minimize these EMI problems, several techniques can be applied. In this paper, insertion of an optimized passive EMI filter is proposed. This filter is optimized by taking into account real impedances of each part of a considered AC motor drive system contrarily to commercial EMI filters designed by considering internal impedance of disturbance source and load, equal to 50Ω. Employing the latter EMI filter would make EMI minimization less effective. The proposed EMI filter optimization is mainly dedicated to minimize common mode (CM) currents due to its most dominant effects in this kind of system. The efficiency of the proposed optimization method using two-port network approach is deduced by comparing the minimized CM current spectra to an applied normative level (ex. DO-160D in aeronautics).

  15. A wideband high common mode rejection ratio amplifier and phase-locked loop demodulator for multifrequency impedance measurement.

    Science.gov (United States)

    Goovaerts, H G; Faes, T J; Raaijmakers, E; Heethaar, R M

    1998-11-01

    Design considerations and implementation of a multifrequency measuring channel for application in the field of bio-impedance measurement are discussed in this paper. The input amplifier has a differential configuration which is electrically isolated from the remaining circuits. Transformer coupling provides improved common mode rejection when compared to non-isolated input stages. The frequency characteristic of the section between input and demodulator is flat within +/- 0.1 dB between 4 kHz and 1024 kHz. The synchronous demodulator is based on a wideband switched video amplifier. In contrast to commonly used lock--in techniques, the carrier for demodulation is recovered from the input signal by means of a phase-locked loop. This method ensures zero phase shift with respect to the input signal and improves the accuracy of measurement. The system has been developed primarily for thoracic impedance cardiography (TIC) but has also successfully been applied in the field of total body bio-impedance analysis (BIA). At present an electrical impedance tomograph is under development based on the instrumentation described. Results regarding the measurement range and accuracy are given and some recordings of patient data are shown.

  16. 高共模输入电平的迟滞比较器设计%Design of Hysteresis Comparator with High Common Mode Input Level

    Institute of Scientific and Technical Information of China (English)

    鞠家欣; 张晋芳; 廖永波; 鲍嘉明; 杨兵

    2011-01-01

    A novel hysteresis comparator based on the bipolar technology was proposed. This comparator has the advantages of high common mode level and low power dissipation that the traditional circuit structure possesses. In comparison to the traditional circuit, an emitter follower is reduced. In addition, in order to remain the stability of the two-stage operational amplifier in this hysteresis comparator, the frequency compensation was studied. The circuit stability was simulated, and the phase margin attained 60°. This hysteresis comparator was realized by CSMC 1 u.m bipolar technology. The measured results show that the upper threshold voltage is 7. 4 V, the lower threshold voltage 6. 92 V, the hysteresis voltage is 0. 48 V, the output high level is about 0. 76 V, and the circuit works stably.%提出了一种新颖的基于双极工艺的迟滞比较器,该电路在保持了传统电路的高共模输入电平和低功耗的优点的同时,在电路结构上比传统的电路节省了一级射随器.此外,为了保证该迟滞比较器中两级运算放大器的稳定性还进行了频率补偿的研究,并对该电路的稳定性进行了仿真,其仿真结果保证了60°的相位裕度.该迟滞比较器的电路使用华润上华1 μm双极晶体管工艺实现,芯片测试结果表明,其上阈值点为7.4V,下阈值点为6.92 V,迟滞电压约为0.48 V,输出高电平约为0.76 V,电路工作稳定.

  17. Enhanced analogue front-end for the measurement of the high state of wide-band voltage pulses with 87 dB common-mode rejection ratio and ±0.65 ppm 1-day offset stability

    Science.gov (United States)

    Arpaia, Pasquale; Baccigalupi, Carlo; Martino, Michele

    2015-09-01

    An improved analogue front-end for measuring the high state of trapezoidal voltage pulses with transition duration of 3 μs is presented. A new measurement system, composed by a front-end and the state-of-the-art acquisition board NI PXI-5922, has been realized with improved Common Mode Rejection Ratio (CMRR) of more than 87 dB at DC and 3-sigma stability of ±0.65 ppm over 1 day. After highlighting the main design enhancements with respect to state-of-the-art solutions, the CMRR measurement is reported. The output drift due to temperature and humidity is assessed to be negligible. Finally, the worst-case repeatability is measured both with shorted-to-ground inputs and with an applied common-mode voltage of 10 V, which represents the nominal working condition.

  18. Enhanced analogue front-end for the measurement of the high state of wide-band voltage pulses with 87 dB common-mode rejection ratio and ±0.65 ppm 1-day offset stability

    CERN Document Server

    AUTHOR|(SzGeCERN)712364; Arpaia, Pasquale; Martino, Michele

    2015-01-01

    An improved analogue front-end for measuring the high state of trapezoidal voltage pulses with transition duration of 3 μs is presented. A new measurement system, composed by a front-end and the state-of-the-art acquisition board NI PXI-5922, has been realized with improved Common Mode Rejection Ratio (CMRR) of more than 87 dB at DC and 3-sigma stability of }0.65 ppm over 1 day. After highlighting the main design enhancements with respect to state-of-the-art solutions, the CMRR measurement is reported. The output drift due to temperature and humidity is assessed to be negligible. Finally, the worst-case repeatability is measured both with shorted-to-ground inputs and with an applied common-mode voltage of 10 V, which represents the nominal working condition.

  19. Shaping the spectra of the line-to-line voltage using signal injection in the common mode voltage

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Rasmussen, Peter Omand; Pedersen, John Kim

    2009-01-01

    A drawback of Pulse Width Modulation in electrical drives is the high harmonic content of the line to line voltages, which gives rise to Electro-Magnetic Interference and acoustic noise. By injection of a signal into the common mode voltage, the fundamental is not affected, but new frequency...... components are introduced in the line to line voltage spectrum. This paper introduces a new analytical method for estimation of the line to line voltage spectrum, where sinusoidal signal is injected into the common mode voltage. Based on the analytical calculations, also a new fixed carrier frequency quasi...

  20. OTA a wide common mode low power

    Directory of Open Access Journals (Sweden)

    Héctor Iván Gómez-Ortiz

    2016-07-01

    Full Text Available This paper presents the design of an operational transconductance amplifier OTA operating in sub-threshold region for low power consumption. Simulations were performed in SYNOPSYS tools program for a 180nm technology. The differential amplifier is supplied with a VDD of 600mV, and has a load capacitance of 15pF. Amplifier gain is 60.08dB with unity-gain frequency of 21.7kHz, and a phase margin greater than 50degrees. Wide common mode operation is achieved by using complementary input differential pairs (NMOS and PMOS showing a range of operation of 500mV.

  1. High level white noise generator

    Science.gov (United States)

    Borkowski, Casimer J.; Blalock, Theron V.

    1979-01-01

    A wide band, stable, random noise source with a high and well-defined output power spectral density is provided which may be used for accurate calibration of Johnson Noise Power Thermometers (JNPT) and other applications requiring a stable, wide band, well-defined noise power spectral density. The noise source is based on the fact that the open-circuit thermal noise voltage of a feedback resistor, connecting the output to the input of a special inverting amplifier, is available at the amplifier output from an equivalent low output impedance caused by the feedback mechanism. The noise power spectral density level at the noise source output is equivalent to the density of the open-circuit thermal noise or a 100 ohm resistor at a temperature of approximately 64,000 Kelvins. The noise source has an output power spectral density that is flat to within 0.1% (0.0043 db) in the frequency range of from 1 KHz to 100 KHz which brackets typical passbands of the signal-processing channels of JNPT's. Two embodiments, one of higher accuracy that is suitable for use as a standards instrument and another that is particularly adapted for ambient temperature operation, are illustrated in this application.

  2. Parasitic Effects of Grounding Paths on Common-Mode EMI Filter's Performance in Power Electronics Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shuo [ORNL; Maillet, Yoann [Virginia Polytechnic Institute and State University (Virginia Tech); Wang, Fei [ORNL; Lai, Rixin [General Electric; Luo, Fang [Virginia Polytechnic Institute and State University (Virginia Tech); Boroyevich, Dushan [Virginia Polytechnic Institute and State University (Virginia Tech)

    2010-01-01

    High-frequency common-mode (CM) electromagnetic-interference (EMI) noise is difficult to suppress in electronics systems. EMI filters are used to suppress CM noise, but their performance is greatly affected by the parasitic effects of the grounding paths. In this paper, the parasitic effects of the grounding paths on an EMI filter's performance are investigated in a motor-drive system. The effects of the mutual inductance between two grounding paths are explored. Guidelines for the grounding of CM EMI filters are derived. Simulations and experiments are finally carried out to verify the theoretical analysis.

  3. Common mode chokes and optimisation aspects

    Science.gov (United States)

    Kut, T.; Lücken, A.; Dickmann, S.; Schulz, D.

    2014-11-01

    Due to the increasing electrification of modern aircraft, as a result of the More Electric Aircraft concept, new strategies and approaches are required to fulfil the strict EMC aircraft standards (DO-160/ED-14-Sec. 20). Common mode chokes are a key component of electromagnetic filters and often oversized because of the unknown impedance of the surrounding power electronic system. This oversizing results in an increase of weight and volume. It has to be avoided as far as possible for mobile applications. In this context, an advanced method is presented to measure these impedances under operating conditions. Furthermore, the different parameters of the inductance design is explained and an optimisation for weight and volume is introduced.

  4. Analysis of common mode inductors and optimization aspects

    NARCIS (Netherlands)

    Roc'h, A.; Leferink, Frank Bernardus Johannes; Zare, Firuz

    2011-01-01

    The common mode inductors, or common mode chokes, are a key component of electromagnetic interference filters. Engineers usually face significant design challenges such as size, cost and weight while working with these components. To avoid the construction of several prototypes, often oversized, eng

  5. Comparison of Multilevel Inverters for the Reduction of Common Mode Voltage

    Directory of Open Access Journals (Sweden)

    Muhammad JAMIL

    2013-02-01

    Full Text Available This paper presents a comparison between NPC (neutral point clamped and H-cascaded multilevel inverters by considering the increas or decrease of harmonics in the output line to line voltages,  phase voltages and common mode voltage. Multilevel voltage source converters are getting increased importance for applications in the medium and high voltage range. A conventional two-level PWM (pulse width modulated inverter generates high frequency common mode voltage with high dv/dt. In the same way, commonly used multilevel inverter modulation schemes generate common mode voltage. Common mode voltage may cause motor shaft voltages, bearing currents and EMI (electromagnetic interference. Common mode voltage depends not only on switching method but also on earth mass. The use of earth mass on a proper place in the circuit can reduce the common mode voltage. Sinusoidal (sine-triangle PWM scheme is being used for this purpose and simulation results are being presented in this paper by using software “Simplorer” and “Post Processor Day”.

  6. EEG acquisition system based on active electrodes with common-mode interference suppression by Driving Right Leg circuit.

    Science.gov (United States)

    Guermandi, Marco; Bigucci, Alessandro; Franchi Scarselli, Eleonora; Guerrieri, Roberto

    2015-01-01

    We present a system for the acquisition of EEG signals based on active electrodes and implementing a Driving Right Leg circuit (DgRL). DgRL allows for single-ended amplification and analog-to-digital conversion, still guaranteeing a common mode rejection in excess of 110 dB. This allows the system to acquire high-quality EEG signals essentially removing network interference for both wet and dry-contact electrodes. The front-end amplification stage is integrated on the electrode, minimizing the system's sensitivity to electrode contact quality, cable movement and common mode interference. The A/D conversion stage can be either integrated in the remote back-end or placed on the head as well, allowing for an all-digital communication to the back-end. Noise integrated in the band from 0.5 to 100 Hz is comprised between 0.62 and 1.3 μV, depending on the configuration. Current consumption for the amplification and A/D conversion of one channel is 390 μA. Thanks to its low noise, the high level of interference suppression and its quick setup capabilities, the system is particularly suitable for use outside clinical environments, such as in home care, brain-computer interfaces or consumer-oriented applications.

  7. Fast High-Quality Noise

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Wyvill, Geoff

    2007-01-01

    At the moment the noise functions available in a graphics programmer's toolbox are either slow to compute or they involve grid-line artifacts making them of lower quality. In this paper we present a real-time noise computation with no grid-line artifacts or other regularity problems. In other wor...

  8. Grounding Effect on Common Mode Interference of Underground Inverter

    Directory of Open Access Journals (Sweden)

    CHENG Qiang

    2013-09-01

    Full Text Available For the neutral point not grounded characteristics of underground power supply system in coal mine, this paper studied common mode equivalent circuit of underground PWM inverter, and extracted parasitic parameters of interference propagation path. The author established a common mode and differential mode model of underground inverter. Taking into account the rise time of PWM, the simulation results of conducted interference by Matlab software is compared with measurement spectrum on the AC side and motor side of converter, the difference is consistent showing that the proposed method has some validity. After Comparison of calculation results by Matlab simulation ,it can be concluded that ungrounded neutral of transformer could redue common mode current in PWM system, but not very effective, the most efficient way is to increase grounding  impedance of  inverter and motor.

  9. Asymptotics of high order noise corrections

    CERN Document Server

    Sondergaard, N; Pálla, G; Voros, A; Sondergaard, Niels; Vattay, Gabor; Palla, Gergely; Voros, Andre

    1999-01-01

    We consider an evolution operator for a discrete Langevin equation with a strongly hyperbolic classical dynamics and noise with finite moments. Using a perturbative expansion of the evolution operator we calculate high order corrections to its trace in the case of a quartic map and Gaussian noise. The leading contributions come from the period one orbits of the map. The asymptotic behaviour is investigated and is found to be independent up to a multiplicative constant of the distribution of noise.

  10. Common mode behavior in grid connected DC and AC decoupled PV Inverter topologies

    Directory of Open Access Journals (Sweden)

    Sundar D. John

    2016-09-01

    Full Text Available The transformer-less grid connected inverters are gaining more popularity due to their high efficiency, very low ground leakage current and economic feasibility especially in photovoltaic systems. The major issue which surfaces these systems is that of common mode leakage current which arises due to the absence of an electrical transformer connected between the inverter and the utility grid. Several topologies have evolved to reduce the impact of common mode leakage current and a majority of them have succeeded in eliminating the impacts and have well kept them within the limits of grid standards. This paper compares and analyses the impact of the common mode leakage current for four popular inverter configurations through simulation of the topologies such as H5, H6, HERIC and FBZVR inverters.

  11. Common mode voltage in case of transformerless PV inverters connected to the grid

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Teodorescu, Remus; Liserre, Marco

    2008-01-01

    For safety reasons grid connected PV systems include galvanic isolation. In case of transformerless inverters, the leakage ground current through the parasitic capacitance of the PV panels, can reach very high values. A common-mode model based on analytical approach is introduced, used to predict...... the common-mode behavior, at frequencies lower than 50kHz, of the selected topologies and to explain the influence of system imbalance on the leakage current. It will be demonstrated that the neutral inductance has a crucial influence on the leakage current. Finally experimental results will be shown...

  12. Behavioral model for common mode filter and performance optimization aspects

    NARCIS (Netherlands)

    Roc'h, A.; Bergsma, H.; Bergsma, J.G.; Leferink, Frank Bernardus Johannes

    2008-01-01

    A well designed common mode filter for motor drive application can significantly improve the level of electromagnetic interference generated by the cable and the motor housing. The subsequent design of this filter is strongly dependent on the actual in situ parameters of the motor drive and often

  13. A high speed digital noise generator

    Science.gov (United States)

    Obrien, J.; Gaffney, B.; Liu, B.

    In testing of digital signal processing hardware, a high speed pseudo-random noise generator is often required to simulate an input noise source to the hardware. This allows the hardware to be exercised in a manner analogous to actual operating conditions. In certain radar and communication environments, a noise generator operating at speeds in excess of 60 MHz may be required. In this paper, a method of generating high speed pseudo-random numbers from an arbitrarily specified distribution (Gaussian, Log-Normal, etc.) using a transformation from a uniform noise source is described. A noise generator operating at 80 MHz has been constructed. Different distributions can be readily obtained by simply changing the ROM set. The hardware and test results will be described. Using this approach, the generation of pseudo-random sequences with arbitrary distributions at word rates in excess of 200 MHz can be readily achieved.

  14. Experimental investigation on the input common mode impedance of a motor and its cable up to 1GHz

    NARCIS (Netherlands)

    Roc'h, A.; Leferink, Frank Bernardus Johannes

    2014-01-01

    The purpose is to highlight the equivalence of the common mode impedance presented to the noise source of the motor drive with the impedance of an antenna. Designable parameters such as the length of the cable or the height above the ground have been taken into account. The equivalence is

  15. The High Price of Noise Exposure

    Science.gov (United States)

    ... Issues Hearing Disorders The High Price of Noise Exposure Past Issues / Fall 2008 Table of Contents For ... on both loudness and time—the longer the exposure, the more likely the damage. In addition, the ...

  16. Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter

    Directory of Open Access Journals (Sweden)

    Pradyumn Chaturvedi

    2012-01-01

    Full Text Available Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV. Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD, phase opposition disposition (POD by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.

  17. Low noise and high CMRR front-end amplifier dedicated to portable EEG acquisition system.

    Science.gov (United States)

    Chebli, Robert; Sawan, Mohamad

    2013-01-01

    This paper concerns the design and implementation of a fully integrated low noise and high CMRR rail-to-rail preamplifier dedicated to EEG acquisition channel. The preamplification technique is based on two complementary CMOS True Logarithmic Amplifier (TLA) stages connected in parallel. The TLA largely amplifies small amplitude of EEG signals, and moderately the large amplitude ones created during epileptic. A chopper stabilization technique is used to filter the 1/ƒ noise and the DC offset voltage of the input CMOS transistors and to increase the common-mode rejection ratio (CMRR). Due to the TLA structure, a high CMRR and high power supply rejection ratio are achieved and the signal-to-noise ratio (of the channel is better enhanced). To snugly fit the ADC input window to the EEG signal magnitude a new programming gain approach is implemented. Also, a chopper spike filter is used to cancel the spike voltages generated by the charge injections of modulator/demodulator switches. The proposed preamplifier is implemented in 0.18 µm CMOS technology. Post-layout simulation results exhibit 253 dB @50/60 Hz as CMRR, 500 nVrms @100 Hz as input-referred noise while consuming 55 µA from a 1.8 V supply.

  18. Noise from high speed maglev systems: Noise sources, noise criteria, preliminary design guidelines for noise control, and recommendations for acoustical test facility for maglev research

    Science.gov (United States)

    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.

  19. Noise of Embedded High Aspect Ratio Nozzles

    Science.gov (United States)

    Bridges, James E.

    2011-01-01

    A family of high aspect ratio nozzles were designed to provide a parametric database of canonical embedded propulsion concepts. Nozzle throat geometries with aspect ratios of 2:1, 4:1, and 8:1 were chosen, all with convergent nozzle areas. The transition from the typical round duct to the rectangular nozzle was designed very carefully to produce a flow at the nozzle exit that was uniform and free from swirl. Once the basic rectangular nozzles were designed, external features common to embedded propulsion systems were added: extended lower lip (a.k.a. bevel, aft deck), differing sidewalls, and chevrons. For the latter detailed Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) simulations were made to predict the thrust performance and to optimize parameters such as bevel length, and chevron penetration and azimuthal curvature. Seventeen of these nozzles were fabricated at a scale providing a 2.13 inch diameter equivalent area throat." ! The seventeen nozzles were tested for far-field noise and a few data were presented here on the effect of aspect ratio, bevel length, and chevron count and penetration. The sound field of the 2:1 aspect ratio rectangular jet was very nearly axisymmetric, but the 4:1 and 8:1 were not, the noise on their minor axes being louder than the major axes. Adding bevel length increased the noise of these nozzles, especially on their minor axes, both toward the long and short sides of the beveled nozzle. Chevrons were only added to the 2:1 rectangular jet. Adding 4 chevrons per wide side produced some decrease at aft angles, but increased the high frequency noise at right angles to the jet flow. This trend increased with increasing chevron penetration. Doubling the number of chevrons while maintaining their penetration decreased these effects. Empirical models of the parametric effect of these nozzles were constructed and quantify the trends stated above." Because it is the objective of the Supersonics Project that

  20. Common-Mode EMI Reduction in Switching Flyback Power Supply by Implementing Cancellation Method of Heat-Sink Capacitor

    Directory of Open Access Journals (Sweden)

    Mohammad Rouholah Yazdani

    2015-01-01

    Full Text Available Electromagnetic compatibility in switching power converters which are noise sources themselves, has a special importance. Electromagnetic interference (EMI in the form of conducted or radiated reaches to sensitive sections and interferes with their operation. On the other, electromagnetic compatibility (EMC standards causes another forces to reduce noise in switching converters. Major part of noise is due to the common-mode (CM current passes through parasitic elements to the circuit ground (Earth. One of the important parasitic elements from the CM noise viewpoint is the switch heat-sink capacitor (common-mode capacitor. In this paper, a cancellation method of the heat-sink capacitor via a passive circuit is proposed in a 50W isolated flyback converter and is also modeled in OrCAD software. Also, experimental measurement results of the CM electromagnetic interference in regular and proposed flyback converter prototypes are presented to examine the modeling accuracy. Based on the experimental results, significant reduction of CM-EMI is verified after applying the cancellation method of the heat-sink capacitor.

  1. A LOW NOISE, HIGH-SPEED COMPENSATED CMOS OP-AMP DESIGN TECHNIQUE

    Directory of Open Access Journals (Sweden)

    SOUMYA SHATAKSHI PANDA

    2013-01-01

    Full Text Available In this paper, we have proposed a new methodology for the design of low frequency, low noise and high speed compensated CMOS op-amp which specifies open loop circuit parameters to obtain enhanced gain, settling time and closed loop stability. The op-amp which we have designed consists of an Operational Transconductance Amplifier (OTA followed by an output buffer. The OTA design involves the use of a continuous-time Common mode feedback circuit which maintains the output common voltage at the required level while maximizing the output swing and the desired compensation is done with a capacitor connected between the input and output of the buffer. The low noise high speed Op-Amp is designed using 180nm CMOS technology and exhibits 88 dB DC gain. For a parallel combination of 2 pF and 1 kΩ load, the unity gain frequency and phase margin are found to be 251 MHz and 37o respectively. Under the same load condition, the proposed compensation method results in a roughly 1.8 times increase in unity gain frequency i.e 392 MHz and a 33o improvement in the phase marginas compared to the conventional approach.

  2. Differential microstrip lines with reduced crosstalk and common mode effect based on spoof surface plasmon polaritons.

    Science.gov (United States)

    Wu, Jin Jei; Hou, Da Jun; Liu, Kexin; Shen, Linfang; Tsai, Chi An; Wu, Chien Jang; Tsai, Dichi; Yang, Tzong-Jer

    2014-11-03

    We apply the concept of spoof surface plasmon polaritons (SPPs) to the design of differential microstrip lines by introducing periodic subwavelength corrugations on their edges. The dispersion relation and field distribution of those lines are analyzed numerically. And then through designing practical coupling circuits, we found that compared with conventional differential microstrip lines, the electromagnetic field can be strongly confined inside the grooves of the corrugated microstrip lines, so the crosstalk between the differential pair and the adjacent microstrip lines is greatly reduced, and the conversion from the differential signal to the common mode signal can also be effectively suppressed. The propagation length of those lines is also very long in a wide band. Moreover, the experimental results in time domain demonstrate those lines perform very well in high-speed circuit. Therefore, those novel kinds of spoof SPPs based differential microstrip lines can be widely utilized in high-density microwave circuits and guarantee signal integrity in high-speed systems.

  3. Analysis of external noise spectrum of high-speed railway

    Institute of Scientific and Technical Information of China (English)

    邓永权; 肖新标; 何宾; 金学松

    2014-01-01

    A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteristics considered here include identifying the exterior main sources and their locations, their frequency components including the Doppler effect due to the noise sources moving at high speed, the sound field intensity around the train in high-speed operation, the sound radiation path out of the train, and the pressure level and frequency components of the noise at the measuring points specified by the International Organization for Standardization(ISO). The characteristics of the high-speed train exterior noise of the high speed railways in operation were introduced. The advanced measuring systems and their principles for clearly indentifying the exterior noise sources were discussed in detail. Based on the concerned noise results measured at sites, a prediction model was developed to calculate the sound level and the characteristics of the exterior noise at any point where it is difficult to measure and to help to make the exterior noise spectrums. This model was also verified with the test results. The verification shows that there is a good agreement between the theoretical and experimental results.

  4. Analysis of Adaptive Interference Cancellation Using Common-Mode Information in Wireline Communications

    Directory of Open Access Journals (Sweden)

    Per Ola Börjesson

    2007-01-01

    Full Text Available Joint processing of common-mode (CM and differential-mode (DM signals in wireline transmission can yield significant improvements in terms of throughput compared to using only the DM signal. Recent work proposed the employment of an adaptive CM-reference-based interference canceller and reported performance improvements based on simulation results. This paper presents a thorough investigation of the cancellation approach. A subchannel model of the CM-aided wireline channel is presented and the Wiener solutions for different adaptation strategies are derived. It is shown that a canceller, whose coefficients are adapted while the far-end transmitter is silent, yields a signal-to-noise power ratio (SNR that is higher than the SNR at the DM channel output for a large class of practically relevant cases. Adaptation while the useful far-end signal is present yields a front-end whose output SNR is considerably lower compared to the SNR of the DM channel output. The results are illustrated by simulations based on channel measurement data.

  5. Study on low-phase-noise optoelectronic oscillator and high-sensitivity phase noise measurement system.

    Science.gov (United States)

    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.

  6. Research on Aerodynamic Noise Reduction for High-Speed Trains

    Directory of Open Access Journals (Sweden)

    Yadong Zhang

    2016-01-01

    Full Text Available A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD/Ffowcs Williams-Hawkings (FW-H acoustic analogy. An analysis of noise reduction methods based on the main noise sources was performed. An aerodynamic noise model for a full-scale high-speed train, including three coaches with six bogies, two inter-coach spacings, two windscreen wipers, and two pantographs, was established. Several low-noise design improvements for the high-speed train were identified, based primarily on the main noise sources; these improvements included the choice of the knuckle-downstream or knuckle-upstream pantograph orientation as well as different pantograph fairing structures, pantograph fairing installation positions, pantograph lifting configurations, inter-coach spacings, and bogie skirt boards. Based on the analysis, we designed a low-noise structure for a full-scale high-speed train with an average sound pressure level (SPL 3.2 dB(A lower than that of the original train. Thus, the noise reduction design goal was achieved. In addition, the accuracy of the aerodynamic noise calculation method was demonstrated via experimental wind tunnel tests.

  7. Noise of high-performance aircraft at afterburner

    Science.gov (United States)

    Tam, Christopher K. W.; Parrish, Sarah A.

    2015-09-01

    The noise from a high-performance aircraft at afterburner is investigated. The main objective is to determine whether the dominant noise components are the same or similar to those of a hot supersonic laboratory jet. For this purpose, measured noise data from F-22A Raptors are analyzed. It is found, based on both spectral and directivity data, that there is a new dominant noise component in addition to the usual turbulent mixing noise. The characteristic features of the new noise component are identified. Measured data indicates that the new noise component is observed only when the rate of fuel burn of the engine is increased significantly above that of the intermediate power setting. This suggests that the new noise component is combustion related. The possibility that it is indirect combustion noise generated by the passage of hot spots from the afterburner through the nozzle of the jet is investigated. Because flow and temperature data were not measured in the F-22A engine tests, to provide support to the proposition, numerical simulations of indirect combustion noise generation due to the passing of an entropy wave pulse (a hot spot) through a military-style nozzle are carried out. Sound generation is observed at the front and at the back of the pulse. This creates a fast and a slow acoustic wave as the sound radiates out from the nozzle exit. Quantitative estimates of the principal directions of acoustic radiation due to the emitted fast and slow acoustic waves are made. It is found that there are reasonably good agreements with measured data. To estimate the intensity level (IL) of the radiated indirect combustion noise, a time-periodic entropy wave train of 15 percent temperature fluctuation is used as a model of the hot spots coming out of the afterburner. This yields an IL of 175.5 dB. This is a fairly intense noise source, well capable of causing the radiation of the new jet noise component.

  8. Planar quadrature RF transceiver design using common-mode differential-mode (CMDM transmission line method for 7T MR imaging.

    Directory of Open Access Journals (Sweden)

    Ye Li

    Full Text Available The use of quadrature RF magnetic fields has been demonstrated to be an efficient method to reduce transmit power and to increase the signal-to-noise (SNR in magnetic resonance (MR imaging. The goal of this project was to develop a new method using the common-mode and differential-mode (CMDM technique for compact, planar, distributed-element quadrature transmit/receive resonators for MR signal excitation and detection and to investigate its performance for MR imaging, particularly, at ultrahigh magnetic fields. A prototype resonator based on CMDM method implemented by using microstrip transmission line was designed and fabricated for 7T imaging. Both the common mode (CM and the differential mode (DM of the resonator were tuned and matched at 298MHz independently. Numerical electromagnetic simulation was performed to verify the orthogonal B1 field direction of the two modes of the CMDM resonator. Both workbench tests and MR imaging experiments were carried out to evaluate the performance. The intrinsic decoupling between the two modes of the CMDM resonator was demonstrated by the bench test, showing a better than -36 dB transmission coefficient between the two modes at resonance frequency. The MR images acquired by using each mode and the images combined in quadrature showed that the CM and DM of the proposed resonator provided similar B1 coverage and achieved SNR improvement in the entire region of interest. The simulation and experimental results demonstrate that the proposed CMDM method with distributed-element transmission line technique is a feasible and efficient technique for planar quadrature RF coil design at ultrahigh fields, providing intrinsic decoupling between two quadrature channels and high frequency capability. Due to its simple and compact geometry and easy implementation of decoupling methods, the CMDM quadrature resonator can possibly be a good candidate for design blocks in multichannel RF coil arrays.

  9. Planar quadrature RF transceiver design using common-mode differential-mode (CMDM) transmission line method for 7T MR imaging.

    Science.gov (United States)

    Li, Ye; Yu, Baiying; Pang, Yong; Vigneron, Daniel B; Zhang, Xiaoliang

    2013-01-01

    The use of quadrature RF magnetic fields has been demonstrated to be an efficient method to reduce transmit power and to increase the signal-to-noise (SNR) in magnetic resonance (MR) imaging. The goal of this project was to develop a new method using the common-mode and differential-mode (CMDM) technique for compact, planar, distributed-element quadrature transmit/receive resonators for MR signal excitation and detection and to investigate its performance for MR imaging, particularly, at ultrahigh magnetic fields. A prototype resonator based on CMDM method implemented by using microstrip transmission line was designed and fabricated for 7T imaging. Both the common mode (CM) and the differential mode (DM) of the resonator were tuned and matched at 298MHz independently. Numerical electromagnetic simulation was performed to verify the orthogonal B1 field direction of the two modes of the CMDM resonator. Both workbench tests and MR imaging experiments were carried out to evaluate the performance. The intrinsic decoupling between the two modes of the CMDM resonator was demonstrated by the bench test, showing a better than -36 dB transmission coefficient between the two modes at resonance frequency. The MR images acquired by using each mode and the images combined in quadrature showed that the CM and DM of the proposed resonator provided similar B1 coverage and achieved SNR improvement in the entire region of interest. The simulation and experimental results demonstrate that the proposed CMDM method with distributed-element transmission line technique is a feasible and efficient technique for planar quadrature RF coil design at ultrahigh fields, providing intrinsic decoupling between two quadrature channels and high frequency capability. Due to its simple and compact geometry and easy implementation of decoupling methods, the CMDM quadrature resonator can possibly be a good candidate for design blocks in multichannel RF coil arrays.

  10. Research on Aerodynamic Noise Reduction for High-Speed Trains

    OpenAIRE

    Yadong Zhang; Jiye Zhang; Tian Li; Liang Zhang; Weihua Zhang

    2016-01-01

    A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H)...

  11. Research on Aerodynamic Noise Reduction for High-Speed Trains

    OpenAIRE

    Yadong Zhang; Jiye Zhang; Tian Li; Liang Zhang; Weihua Zhang

    2016-01-01

    A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H)...

  12. Method of Measuring Common-Mode Current Conversion Coefficient for Estimating Variation in Radiated Emission from Printed Circuit Board Components

    Directory of Open Access Journals (Sweden)

    C. Ho

    2014-06-01

    Full Text Available This work describes the measurement of the common-mode current conversion coefficient for a microstrip line with solid and slotted ground planes by using a VNA with a BCI probe. The radiated emissions estimated by the common-mode current conversion coefficient are further compared with those obtained by the FAC measurements. Furthermore, the proposed method was used to estimate radiated emissions from a microstrip bandpass filter. For all of the case studies, results of electromagnetic (EM simulation demonstrate the validity of the measurement results by the proposed method. Highly promising for use in EMI measurement application, the proposed method can estimate the radiated emissions by miniaturized microstrip components on a PCB when pre-tested for compliance with EMI regulations.

  13. Noise

    Science.gov (United States)

    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 ...

  14. Nongrounded Common-Mode Equivalent Circuit for Brushless DC Motor Driven by PWM Inverter

    Science.gov (United States)

    Maetani, Tatsuo; Isomura, Yoshinori; Watanabe, Akihiko; Iimori, Kenichi; Morimoto, Shigeo

    This paper describes nongrounded common-mode equivalent circuit for a motor driven by a voltage-source PWM inverter. When the capacitance of the rotor was small, the phenomenon that polarity of the common mode voltage and shaft voltage reversed was observed. In order to model this phenomenon, the bridge type equivalent circuit is proposed. It is verified with the calculation and experiment that shaft voltage values and polarity are accurately calculated with the proposed equivalent circuit.

  15. Assessment of rural soundscapes with high-speed train noise.

    Science.gov (United States)

    Lee, Pyoung Jik; Hong, Joo Young; Jeon, Jin Yong

    2014-06-01

    In the present study, rural soundscapes with high-speed train noise were assessed through laboratory experiments. A total of ten sites with varying landscape metrics were chosen for audio-visual recording. The acoustical characteristics of the high-speed train noise were analyzed using various noise level indices. Landscape metrics such as the percentage of natural features (NF) and Shannon's diversity index (SHDI) were adopted to evaluate the landscape features of the ten sites. Laboratory experiments were then performed with 20 well-trained listeners to investigate the perception of high-speed train noise in rural areas. The experiments consisted of three parts: 1) visual-only condition, 2) audio-only condition, and 3) combined audio-visual condition. The results showed that subjects' preference for visual images was significantly related to NF, the number of land types, and the A-weighted equivalent sound pressure level (LAeq). In addition, the visual images significantly influenced the noise annoyance, and LAeq and NF were the dominant factors affecting the annoyance from high-speed train noise in the combined audio-visual condition. In addition, Zwicker's loudness (N) was highly correlated with the annoyance from high-speed train noise in both the audio-only and audio-visual conditions. © 2013.

  16. A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement.

    Science.gov (United States)

    Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui

    2014-01-01

    We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO4 laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.

  17. A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui, E-mail: yhzheng@sxu.edu.cn [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)

    2014-01-15

    We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO{sub 4} laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.

  18. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

    Science.gov (United States)

    Liu, Jinzhen; Qiao, Xiaoyan; Wang, Mengjun; Zhang, Weibo; Li, Gang; Lin, Ling

    2014-05-01

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  19. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinzhen; Li, Gang; Lin, Ling, E-mail: linling@tju.edu.cn [State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People' s Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin (China); Qiao, Xiaoyan [College of Physics and Electronic Engineering, Shanxi University, Shanxi (China); Wang, Mengjun [School of Information Engineering, Hebei University of Technology, Tianjin (China); Zhang, Weibo [Institute of Acupuncture and Moxibustion China Academy of Chinese Medical Sciences, Beijing (China)

    2014-05-15

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  20. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system.

    Science.gov (United States)

    Liu, Jinzhen; Qiao, Xiaoyan; Wang, Mengjun; Zhang, Weibo; Li, Gang; Lin, Ling

    2014-05-01

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  1. High frequency microseismic noise as possible earthquake precursor

    Directory of Open Access Journals (Sweden)

    Ivica Sović

    2013-08-01

    Full Text Available Before an earthquake occurs, microseismic noise in high frequency (HF range, i.e. 2-25 Hz, is being generated during preparation process. These signals change the microseismic noise and, consequently, the spectrum of microseismic noise. Time variation of spectra recorded at the same seismological station could imply the change of the state of noise source. We propose the image moment analysis approach to objectively compare microseismic noise spectra. The result could be used for earthquake precursor identification. Expected spectra change is in HF range, so the analysis has been limited to the shallow tectonic earthquakes with epicenters close, up to 15 km, the seismological stations. The method has been tested post festum using four earthquakes in Dinarides which satisfied condition for epicentral distance. The spectra were calculated for noise recorded in time intervals of 10 days before and 6 to 10 days after the earthquakes. Affine moment invariants were calculated for noise spectra which were treated as the input objects. Spectra of the first five days in the series were referent spectra. The classification parameters were Euclidean distances between referent spectra and the spectra for all days in the series, including referent ones. The results have shown that the spectra of the microseismic noise become noticeably different than the other spectra in time intervals one or two days before an earthquake.

  2. Low Power CMOS Operational Amplifier with Integrated Common-Mode Feedback for Data Converter

    Directory of Open Access Journals (Sweden)

    Murad S.A.Z

    2017-01-01

    Full Text Available The development a high-performance design of analog circuits becomes increasingly challenging with the continuous trend towards reducing the voltage supply and low power consumption without neglecting the trade-off among other performance parameters. This paper presents the design and implementation of CMOS operational amplifier (op-amp with integrated common-mode feedback (CMFB circuit for data converter using 0.13-μm Silterra CMOS technology. The folded cascode topology is employed as a main op-amp design because it provides high gain and high bandwidth besides low power consumption. The simulation results indicate that the DC gain of 64.5 dB along 133.1 MHz unity gain bandwidth (UGB is achieved for a 1 pF load capacitor. The slew rate of 22.6 V/μs, the phase margin (PM of 68.4° with settling time of 72.4 ns are obtained. The power consumption of this op-amp is 0.3 mW through voltage supply of 1.8 V.

  3. High-resolution noise radar using slow ADC

    Science.gov (United States)

    Lukin, Konstantin; Vyplavin, Pavlo; Zemlyanyi, Oleg; Lukin, Sergiy; Palamarchuk, Volodymyr

    2011-06-01

    Conventional digital signal processing scheme in noise radars has some limitations related to combination of high resolution and high dynamic range. Those limitations are caused by a tradeoff in performance of currently available ADCs: the faster is ADC the smaller is its depth (number of bits) available. Depth of the ADC determines relation between the smallest and highest observable signals and thus limits its dynamic range. In noise radar with conventional processing the sounding and reference signals are to be digitized at intermediate frequency band and to be processed digitally. The power spectrum bandwidth of noise signal which can be digitized with ADC depends on its sampling rate. The bandwidth of radar signal defines range resolution of any radar: the wider the spectrum the better the resolution. Actually this is the main bottleneck of high resolution Noise Radars: conventional processing doesn't enable to get both high range resolution and high dynamic range. In the paper we present a way to go around this drawback by changing signal processing ideology in noise radar. We present results of our consideration and design of high resolution Noise Radar which uses slow ADCs. The design is based upon generation of both probing and reference signals digitally and realization of their cross-correlation in an analog correlator. The output of the correlator is a narrowband signal that requires rather slow ADC to be sampled which nowadays may give up to 130 dB dynamic range.

  4. Noise Measurements of High Aspect Ratio Distributed Exhaust Systems

    Science.gov (United States)

    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.

  5. Dual Z-Source Inverter With Three-Level Reduced Common-Mode Switching

    DEFF Research Database (Denmark)

    Gao, Feng; Loh, Poh Chiang; Blaabjerg, Frede;

    2007-01-01

    . Modulationwise, the dual inverter can be controlled using a carefully designed carrier-based pulsewidth-modulation (PWM) scheme that will always ensure balanced voltage boosting of the Z-source network while simultaneously achieving reduced common-mode switching. Because of the omission of dead-time delays...... in the dual-inverter PWM scheme, its switched common-mode voltage can be completely eliminated, unlike in traditional inverters, where narrow common-mode spikes are still generated. Under semiconductor failure conditions, the presented PWM schemes can easily be modified to allow the inverter to operate......This paper presents the design of a dual Z-source inverter that can be used with either a single dc source or two isolated dc sources. Unlike traditional inverters, the integration of a properly designed Z-source network and semiconductor switches to the proposed dual inverter allows buck...

  6. Common-mode Voltage Reduction in a Motor Drive System with a Power Factor Correction

    DEFF Research Database (Denmark)

    Adabi, J.; Boora, A.A.; Zare, F.;

    2012-01-01

    to reduce shaft voltage in a three-phase AC motor drive system. In this topology, the AC-DC diode rectifier influences the common-mode voltage generated by the inverter because the placement of the neutral point is changing in different rectifier circuit states. A pulse width modulation technique......Common-mode voltage generated by a power converter in combination with parasitic capacitive couplings is a potential source of shaft voltage in an AC motor drive system. In this study, a three-phase motor drive system supplied with a single-phase AC-DC diode rectifier is investigated in order...... is presented by a proper placement of the zero vectors to reduce the common-mode voltage level, which leads to a cost-effective shaft voltage reduction technique without load current distortion, while keeping the switching frequency constant. Analysis, simulations and experimental implementation have been...

  7. An Optimization System with Parallel Processing for Reducing Common-Mode Current on Electronic Control Unit

    Science.gov (United States)

    Okazaki, Yuji; Uno, Takanori; Asai, Hideki

    In this paper, we propose an optimization system with parallel processing for reducing electromagnetic interference (EMI) on electronic control unit (ECU). We adopt simulated annealing (SA), genetic algorithm (GA) and taboo search (TS) to seek optimal solutions, and a Spice-like circuit simulator to analyze common-mode current. Therefore, the proposed system can determine the adequate combinations of the parasitic inductance and capacitance values on printed circuit board (PCB) efficiently and practically, to reduce EMI caused by the common-mode current. Finally, we apply the proposed system to an example circuit to verify the validity and efficiency of the system.

  8. Common-mode radiation characteristic analysis of connections between cables and metal cases

    Institute of Scientific and Technical Information of China (English)

    Haifeng SONG; Zhiyu CHEN

    2008-01-01

    In this paper,the common-mode radiation characteristic of the connection between a cable and a conductor is analyzed by the electric field integral function(EFIF)and the method of moment(MoM).The RWG basis function is adopted as the conductor basis function,the pulse basis function as the wire basis function and the juncture employs Costa basis function.A scheme of singular region separation is proposed to overcome the integration singularity of juncture matrix elements.Some new conclusions of the common-mode radiation characteristics with the metal case are obtained by numeration.

  9. An ultra-low noise, high-voltage piezo driver

    CERN Document Server

    Pisenti, N C; Reschovsky, B J; Barker, D S; Campbell, G K

    2016-01-01

    We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total RMS noise of $\\approx 100\\mu$V (1 Hz--100 kHz). A low-voltage ($\\pm 10$V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150mA at $\\pm 15$V.

  10. Quantum dot amplifiers with high output power and low noise

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2003-01-01

    Quantum dot semiconductor optical amplifiers have been theoretically investigated and are predicted to achieve high saturated output power, large gain, and low noise figure. We discuss the device dynamics and, in particular, show that the presence of highly inverted barrier states does not limit ...

  11. Conduction Losses and Common Mode EMI Analysis on Bridgeless Power Factor Correction

    DEFF Research Database (Denmark)

    Li, Qingnan; Andersen, Michael Andreas E.; Thomsen, Ole Cornelius

    2009-01-01

    In this paper, a review of Bridgeless Boost power factor correction (PFC) converters is presented at first. Performance comparison on conduction losses and common mode electromagnetic interference (EMI) are analyzed between conventional Boost PFC converter and members of Bridgeless PFC family....... Experiment results are given to validate the efficiency analysis and EMI model building....

  12. PCB Slot Based Transformers to Avoid Common-Mode Resonances in Connected Arrays of Dipoles

    NARCIS (Netherlands)

    Cavallo, D.; Neto, A.; Gerini, G.

    2010-01-01

    The scanning performances of connected arrays are degraded by the excitation of common-mode resonances that are compatible with balanced feeding lines. Here, a strategy to avoid these resonances is outlined. The strategy involves feeding the dipoles via printed circuit board (PCB) based transformers

  13. Hearing Protection for High-Noise Environments

    Science.gov (United States)

    2009-12-31

    based on a modified form of the volumetric Lippmann- Schwinger integral equation, adapted to the treatment of high-contrast problems. It utilizes a...the reformulation of the conventional Lippmann- Schwinger (L-S) equations which we developed in the case of acoustics (Reference 2 in Section 6). By

  14. Noise of High Performance Aircraft at Afterburner

    Science.gov (United States)

    2016-05-04

    Mathematics Florida State University Email: tam@math.fsu.edu Grant Monitor Dr. John Spyropoulous Email: John.Spyropoulous@jsf.mil...of equations (1) and (2). Obviously, the computed spectrum is unacceptable. It is overwhelmed by spurious high frequency oscillations. Figure 2...reasoning suggests that we may, as a first approximation, insert a boxcar window function in the integral of equation (4). That is, equation (4) is

  15. High Capacity and Resistance to Additive Noise Audio Steganography Algorithm

    Directory of Open Access Journals (Sweden)

    Haider Ismael Shahadi

    2011-09-01

    Full Text Available Steganography is the art of message hiding in a cover signal without attracting attention. The requirements of the good steganography algorithm are security, capacity, robustness and imperceptibility, all them are contradictory, therefore, satisfying all together is not easy especially in audio cover signal because human auditory system (HAS has high sensitivity to audio modification. In this paper, we proposed a high capacity audio steganography algorithm with good resistance to additive noise. The proposed algorithm is based on wavelet packet transform and blocks matching. It has capacity above 35% of the input audio file size with acceptable signal to noise ratio. Also, it is resistance to additive Gaussian noise to about 25 db. Furthermore, the reconstruction of actual secret messages does not require the original cover audio signal.

  16. Noise of High-Performance Aircraft at Afterburner

    Science.gov (United States)

    2015-07-11

    50 ft. from the jet exit by the inverse-square law. The data was acquired at four engine power settings. But only data at 3 power settings are found...8217 ’ ’ ’ ’ 10u f/f- J I 1 I I III, 10’ Figure 10. The two similarity spectra of turbulent mixing noise of high-speed jets . In a previous work ...Vibration, Vol. 352, 103-128, 2015), it was found that when the engine was operating at intermediate power, the jet noise of the engine consisted of

  17. High dimensional matrix estimation with unknown variance of the noise

    CERN Document Server

    Klopp, Olga

    2011-01-01

    We propose a new pivotal method for estimating high-dimensional matrices. Assume that we observe a small set of entries or linear combinations of entries of an unknown matrix $A_0$ corrupted by noise. We propose a new method for estimating $A_0$ which does not rely on the knowledge or an estimation of the standard deviation of the noise $\\sigma$. Our estimator achieves, up to a logarithmic factor, optimal rates of convergence under the Frobenius risk and, thus, has the same prediction performance as previously proposed estimators which rely on the knowledge of $\\sigma$. Our method is based on the solution of a convex optimization problem which makes it computationally attractive.

  18. "EFFECTS OF HIGH-SPEED DRILL NOISE ON DENTISTS’ HEARING "

    Directory of Open Access Journals (Sweden)

    F.Akbakhanzadeh

    1978-11-01

    Full Text Available The study deals with noise problems associated with the use of air-turbine drills in dental practice. Noise level measurements were made on various types of dental handpieces, when operated free running and when used to cut tooth tissue. Hearing acuity tests were also undertaken in 12 randomly selected dental surgeons who have been using these drills for a number of years. The results indicate that although the danger to hearing from high speed drills is small, the possibility of hazardous effects-at least, for susceptible ears- is not excluded.

  19. Fast Impulse Noise Removal from Highly Corrupted Images

    CERN Document Server

    Hosseini, Hossein

    2011-01-01

    In this paper, we suggest a general model for the fixed-valued impulse noise and propose a two-stage method for high density noise suppression while preserving the image details. In the first stage, we apply an iterative impulse detector, exploiting the image entropy, to identify the corrupted pixels and then employ an Adaptive Iterative Mean filter (AIM) to restore them. The filter is adaptive in terms of the number of iterations, which is different for each noisy pixel, according to their Euclidean distance from the nearest uncorrupted pixel. Experimental results show that the AIM filter is fast and outperforms the best existing techniques in both objective and subjective performance measures.

  20. Radiation Response of Emerging High Gain, Low Noise Detectors

    Science.gov (United States)

    Becker, Heidi N.; Farr, William H; Zhu, David Q.

    2007-01-01

    Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

  1. Proceedings of the 1987 national conference on noise control engineering: High technology for noise control

    Energy Technology Data Exchange (ETDEWEB)

    Tichy, J.; Hayek, S.

    1987-01-01

    This book consists of nine sections, each containing several papers. The section titles are: Emission: Noise Sources; Physical Phenomena; Noise Control Elements; Vibration: Generation, Transmission, Isolation and Reduction; Immission: Physical Aspects of Environmental Noise; Immission: Effects of Noise; Analysis; Requirements; and Biomedical Uses of Acoustics.

  2. Common-mode rejection in Martin-Puplett spectrometers for astronomical observations at mm-wavelengths

    CERN Document Server

    D'Alessandro, Giuseppe; Masi, Silvia; Schillaci, Alessandro

    2015-01-01

    The Martin-Puplett interferometer (MPI) is a differential Fourier transform spectrometer (FTS), measuring the difference between spectral brightness at two input ports. This unique feature makes the MPI an optimal zero instrument, able to detect small brightness gradients embeddend in a large common background. In this paper we investigate experimentally the common-mode rejection achievable in the MPI at mm wavelengths, and discuss the use of the instrument to measure the spectrum of cosmic microwave background (CMB) anisotropy.

  3. Common-mode rejection in Martin-Puplett spectrometers for astronomical observations at millimeter wavelengths.

    Science.gov (United States)

    D'Alessandro, Giuseppe; de Bernardis, Paolo; Masi, Silvia; Schillaci, Alessandro

    2015-11-01

    The Martin-Puplett interferometer (MPI) is a differential Fourier transform spectrometer that measures the difference between spectral brightness at two input ports. This unique feature makes the MPI an optimal zero instrument, able to detect small brightness gradients embedded in a large common background. In this paper, we experimentally investigate the common-mode rejection achievable in the MPI at millimeter wavelengths, and discuss the use of the instrument to measure the spectrum of cosmic microwave background anisotropy.

  4. A high-resolution ambient seismic noise model for Europe

    Science.gov (United States)

    Kraft, Toni

    2014-05-01

    measurement precision (i.e. earthquake location), while considering this extremely complex boundary condition. To solve this problem I have developed a high-resolution ambient seismic noise model for Europe. The model is based on land-use data derived from satellite imagery by the EU-project CORINE in a resolution of 100x100m. The the CORINE data consists of several land-use classes, which, besides others, contain: industrial areas, mines, urban fabric, agricultural areas, permanent corps, forests and open spaces. Additionally, open GIS data for highways, and major and minor roads and railway lines were included from the OpenStreetMap project (www.openstreetmap.org). This data was divided into three classes that represent good, intermediate and bad ambient conditions of the corresponding land-use class based on expert judgment. To account for noise propagation away from its source a smoothing operator was applied to individual land-use noise-fields. Finally, the noise-fields were stacked to obtain an European map of ambient noise conditions. A calibration of this map with data of existing seismic stations Europe allowed me to estimate the expected noise level in actual ground motion units for the three ambient noise condition classes of the map. The result is a high-resolution ambient seismic noise map, that allows the network designer to make educated predictions on the expected noise level for arbitrary location in Europe. The ambient noise model was successfully tested in several network optimization projects in Switzerland and surrounding countries and will hopefully be a valuable contribution to improving the data quality of microseismic monitoring networks in Europe.

  5. High-Temperature Liners for Broadband Noise Reduction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Core noise will become a larger component of engine noise overall, as more efficient design trends of fan and jet noise reduction technologies are implemented. The...

  6. Passive control of rotorcraft high-speed impulsive noise

    Science.gov (United States)

    Szulc, O.; Doerffer, P.; Tejero, F.

    2016-10-01

    A strong, normal shock wave, terminating a local supersonic area located at the tip of a helicopter blade, not only limits the aerodynamic performance, but also constitutes an origin of the High-Speed Impulsive (HSI) noise. The application of a passive control device (a shallow cavity covered by a perforated plate) just beneath the interaction region weakens the compression level, thus reducing the main source of the HSI noise. The numerical investigation based on the URANS approach and Bohning/Doerffer (BD) transpiration law (SPARC code) confirms a large potential of the new method. Two exemplary implementations, adapted to model helicopter rotors tested at NASA Ames facility in transonic conditions: Caradonna-Tung (lifting, transonic hover) and Caradonna-Laub-Tung (non-lifting, high-speed forward flight), demonstrate the possible gains in terms of the reduction of acoustic pressure fluctuations in the near-field of the blade tip. The CFD results are validated against the experimental data obtained for the reference configurations (no control), while the analysis of the passive control arrangement is based on a purely numerical research. The normal shock wave is effectively eliminated by the wall ventilation exerting a positive impact on the generated level of the HSI noise.

  7. Design & Implementation of High Switching & Low Phase Noise Frequency Synthesizer

    Directory of Open Access Journals (Sweden)

    Ali M. N. Hassan

    2006-01-01

    Full Text Available This research describes the design & implementation of frequency synthesizer using single loop Phase lock loop with the following specifications: Frequency range (1.5 – 2.75 GHz,Step size (1 MHz, Switching time 36.4 µs, & phase noise @10 kHz = -92dBc & spurious -100 dBc The development in I.C. technology provide the simplicity in the design of frequency synthesizer because it implements the phase frequency detector(PFD , prescalar & reference divider in single chip. Therefore our system consists of a single chip contains (low phase noise PFD, charge pump, prescalar & reference divider, voltage controlled oscillator , loop filter & reference oscillator. The single chip is used to provide the following properties :•Low power consumptionSmall size, light weight.Flexibility in selecting crystal oscillator frequencies to fit into the system frequency planning.•High reliability.The application of this synthesizer in frequency hopping systems, satellite communications & radar because it has high switching speed ,low phase noise & low spurious level.

  8. High-Tc SQUIDs: Noise and applications

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hsiao-Mei [Univ. of Houston, TX (United States)

    2001-08-01

    A major challenge in the design and operation of high transition temperature (Tc ) Superconducting Quantum Interference Devices (SQUIDs) is their potential to exhibit substantially higher levels of noise at low frequency f when exposed to earth’s magnetic field. To investigate this problem, we studied the noise of high-Tc SQUIDs, directly coupled magnetometers and multilayer magnetometers in both static and changing magnetic fields. The directly coupled magnetometer consists of a dc SQUID connected to a large area pickup loop in parallel. The multilayer magnetometer involves a multiturn flux transformer inductively coupled to a dc SQUID on a separate substrate. All the devices are made of thin films of the high-Tc superconductor YBa2Cu3O7-δ, patterned into 4 μm linewidths. After cooling in a magnetic field, the devices showed no increase in 1/f noise for fields up to threshold values well above the earth’s magnetic field. The devices were also cooled in a magnetic field that was subsequently turned off. The 1/f noise of bare SQUIDs was unchanged for fields up to 12 μT. The addition of the flux transformer containing flux dams increased the sensitivity to magnetic field by a factor of 43 while reducing the threshold field only moderately, to 5 μT. This result implies that the multilayer magnetometer can be rotated in the earth’s magnetic field through an angle of up to 26o without increasing the low frequency noise. The results of these studies were incorporated into a 5-channel high-Tc magnetocardiography system involving two first-derivative SQUID gradiometers and three reference SQUIDs. Each planar gradiometer consists of a directly coupled SQUID magnetometer inductively coupled to the smaller coil of an asymmetric, two-loop flux transformer. The reference SQUIDs are patterned into 4 μm lines. The outputs of the five channels were subtracted in software to form a second-derivative gradiometer. Its

  9. An investigation of community noise in high-rise residential environments.

    Science.gov (United States)

    Alam, Sheikh Mahbub; Eang, Lee Siew; Tan, Alan; Tiong, Tan Sze

    2010-06-01

    High-rise dwellers in Singapore are often subjected to several community noise sources in close proximity. These include food center, children playground, soccer playground, basketball playground, waste disposal truck, etc. A scientific and reliable approach is required for evaluation of the community noise and its impact on high-rise dwellers. A comprehensive noise survey by a cluster sampling technique, conducted among 522 households in five residential towns in Singapore, showed that community noise was one of the prime sources of noise in a high-rise residential environment. From a subjective noise survey, undertaken concurrent with objective noise measurements, a mean outdoor noise level of 59 dBA was established as an acceptable noise level in the indoor environment. To investigate the level of noise exposure from different community noise sources, software modeling and simulations were carried out. The predicted results were validated with field measured data at five 16 story residential buildings. Analysis of noise exposure data showed that except for waste disposal truck, noise exposure due to other community noise sources (building distance of 15 m) were within the established acceptable noise level. A factor analysis of the survey data identified the key factors related to the disturbance due to community noise sources.

  10. Noise Simulations of the High-Lift Common Research Model

    Science.gov (United States)

    Lockard, David P.; Choudhari, Meelan M.; Vatsa, Veer N.; O'Connell, Matthew D.; Duda, Benjamin; Fares, Ehab

    2017-01-01

    The PowerFLOW(TradeMark) code has been used to perform numerical simulations of the high-lift version of the Common Research Model (HL-CRM) that will be used for experimental testing of airframe noise. Time-averaged surface pressure results from PowerFLOW(TradeMark) are found to be in reasonable agreement with those from steady-state computations using FUN3D. Surface pressure fluctuations are highest around the slat break and nacelle/pylon region, and synthetic array beamforming results also indicate that this region is the dominant noise source on the model. The gap between the slat and pylon on the HL-CRM is not realistic for modern aircraft, and most nacelles include a chine that is absent in the baseline model. To account for those effects, additional simulations were completed with a chine and with the slat extended into the pylon. The case with the chine was nearly identical to the baseline, and the slat extension resulted in higher surface pressure fluctuations but slightly reduced radiated noise. The full-span slat geometry without the nacelle/pylon was also simulated and found to be around 10 dB quieter than the baseline over almost the entire frequency range. The current simulations are still considered preliminary as changes in the radiated acoustics are still being observed with grid refinement, and additional simulations with finer grids are planned.

  11. High signal-to-noise ratio quantum well bolometer materials

    Science.gov (United States)

    Wissmar, Stanley; Höglund, Linda; Andersson, Jan; Vieider, Christian; Savage, Susan; Ericsson, Per

    2006-09-01

    Novel single crystalline high-performance temperature sensing materials (quantum well structures) have been developed for the manufacturing of uncooled infrared bolometers. SiGe/Si and AlGaAs/GaAs quantum wells are grown epitaxially on standard Si and GaAs substrates respectively. The former use holes as charge carriers utilizing the discontinuities in the valence band structure, whereas the latter operate in a similar manner with electrons in the conduction band. By optimizing parameters such as the barrier height (by variation of the germanium/aluminium content respectively) and the fermi level E f (by variation of the quantum well width and doping level) these materials provide the potential to engineer layer structures with a very high temperature coefficient of resistance, TCR, as compared with conventional thin film materials such as vanadium oxide and amorphous silicon. In addition, the high quality crystalline material promises very low 1/f-noise characteristics promoting an outstanding signal to noise ratio and well defined and uniform material properties, A comparison between the two (SiGe/Si and AlGaAs/GaAs) quantum well structures and their fundamental theoretical limits are discussed and compared to experimental results. A TCR of 2.0%/K and 4.5%/K have been obtained experimentally for SiGe/Si and AlGaAs/GaAs respectively. The noise level for both materials is measured as being several orders of magnitude lower than that of a-Si and VOx. These uncooled thermistor materials can be hybridized with read out circuits by using conventional flip-chip assembly or wafer level adhesion bonding. The increased bolometer performance so obtained can either be exploited for increasing the imaging system performance, i. e. obtaining a low NETD, or to reduce the vacuum packaging requirements for low cost applications (e.g. automotive).

  12. Effects of high combustion chamber pressure on rocket noise environment

    Science.gov (United States)

    Pao, S. P.

    1972-01-01

    The acoustical environment for a high combustion chamber pressure engine was examined in detail, using both conventional and advanced theoretical analysis. The influence of elevated chamber pressure on the rocket noise environment was established, based on increase in exit velocity and flame temperature, and changes in basic engine dimensions. Compared to large rocket engines, the overall sound power level is found to be 1.5 dB higher, if the thrust is the same. The peak Strouhal number shifted about one octave lower to a value near 0.01. Data on apparent sound source location and directivity patterns are also presented.

  13. Combined effect of noise and vibration produced by high-speed trains on annoyance in buildings.

    Science.gov (United States)

    Lee, Pyoung Jik; Griffin, Michael J

    2013-04-01

    The effects of noise and vibration on annoyance in buildings during the passage of a nearby high-speed train have been investigated in a laboratory experiment with recorded train noise and 20 Hz vibration. The noises included the effects of two types of façade: windows-open and windows-closed. Subjects were exposed to six levels of noise and six magnitudes of vibration, and asked to rate annoyance using an 11-point numerical scale. The experiment consisted of four sessions: (1) evaluation of noise annoyance in the absence of vibration, (2) evaluation of total annoyance from simultaneous noise and vibration, (3) evaluation of noise annoyance in the presence of vibration, and (4) evaluation of vibration annoyance in the absence of noise. The results show that vibration did not influence ratings of noise annoyance, but that total annoyance caused by combined noise and vibration was considerably greater than the annoyance caused by noise alone. The noise annoyance and the total annoyance caused by combined noise and vibration were associated with subject self-ratings of noise sensitivity. Two classical models of total annoyance due to combined noise sources (maximum of the single source annoyance or the integration of individual annoyance ratings) provided useful predictions of the total annoyance caused by simultaneous noise and vibration.

  14. Passive ultrasonics using sub-Nyquist sampling of high-frequency thermal-mechanical noise.

    Science.gov (United States)

    Sabra, Karim G; Romberg, Justin; Lani, Shane; Degertekin, F Levent

    2014-06-01

    Monolithic integration of capacitive micromachined ultrasonic transducer arrays with low noise complementary metal oxide semiconductor electronics minimizes interconnect parasitics thus allowing the measurement of thermal-mechanical (TM) noise. This enables passive ultrasonics based on cross-correlations of diffuse TM noise to extract coherent ultrasonic waves propagating between receivers. However, synchronous recording of high-frequency TM noise puts stringent requirements on the analog to digital converter's sampling rate. To alleviate this restriction, high-frequency TM noise cross-correlations (12-25 MHz) were estimated instead using compressed measurements of TM noise which could be digitized at a sampling frequency lower than the Nyquist frequency.

  15. High-Fidelity Simulation of Turbofan Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Broadband fan noise ? closely tied to turbulent flow on and around the fan blades ? represents a key challenge to the noise reduction community due to the...

  16. Similarity spectra analysis of high-performance jet aircraft noise.

    Science.gov (United States)

    Neilsen, Tracianne B; Gee, Kent L; Wall, Alan T; James, Michael M

    2013-04-01

    Noise measured in the vicinity of an F-22A Raptor has been compared to similarity spectra found previously to represent mixing noise from large-scale and fine-scale turbulent structures in laboratory-scale jet plumes. Comparisons have been made for three engine conditions using ground-based sideline microphones, which covered a large angular aperture. Even though the nozzle geometry is complex and the jet is nonideally expanded, the similarity spectra do agree with large portions of the measured spectra. Toward the sideline, the fine-scale similarity spectrum is used, while the large-scale similarity spectrum provides a good fit to the area of maximum radiation. Combinations of the two similarity spectra are shown to match the data in between those regions. Surprisingly, a combination of the two is also shown to match the data at the farthest aft angle. However, at high frequencies the degree of congruity between the similarity and the measured spectra changes with engine condition and angle. At the higher engine conditions, there is a systematically shallower measured high-frequency slope, with the largest discrepancy occurring in the regions of maximum radiation.

  17. Dual Z-Source Inverter With Three-Level Reduced Common-Mode Switching

    DEFF Research Database (Denmark)

    Gao, Feng; Loh, Poh Chiang; Blaabjerg, Frede

    2007-01-01

    This paper presents the design of a dual Z-source inverter that can be used with either a single dc source or two isolated dc sources. Unlike traditional inverters, the integration of a properly designed Z-source network and semiconductor switches to the proposed dual inverter allows buck......-boost power conversion to be performed over a wide modulation range, with three-level output waveforms generated. The connection of an additional transformer to the inverter ac output also allows all generic wye-or delta-connected loads with three-wire or four-wire configuration to be supplied by the inverter....... Modulationwise, the dual inverter can be controlled using a carefully designed carrier-based pulsewidth-modulation (PWM) scheme that will always ensure balanced voltage boosting of the Z-source network while simultaneously achieving reduced common-mode switching. Because of the omission of dead-time delays...

  18. Anomalously high noise levels in a fibre Bragg grating semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Kurnosov, V D; Kurnosov, K V [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2015-01-31

    Taking into account gain nonlinearity allows one to obtain anomalously high noise levels in a fibre Bragg grating laser diode. This paper examines the effect of the gain nonlinearity due to spectral hole burning on noise characteristics. (lasers)

  19. Noise reduction in muon tomography for detecting high density objects

    CERN Document Server

    Benettoni, M; Bonomi, G; Calvagno, G; Calvini, P; Checchia, P; Cortelazzo, G; Cossutta, L; Donzella, A; Furlan, M; Gonella, F; Pegoraro, M; Garola, A Rigoni; Ronchese, P; Squarcia, S; Subieta, M; Vanini, S; Viesti, G; Zanuttigh, P; Zenoni, A; Zumerle, G

    2013-01-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. A new and innovative method is presented in this paper to handle the density fluctuations (noise) of reconstructed images, that are a known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect in short times high density materials, such as lead, when surrounded by light or medium density material. A comparison with algorithms published in literature is also presented.

  20. Noise reduction in muon tomography for detecting high density objects

    Science.gov (United States)

    Benettoni, M.; Bettella, G.; Bonomi, G.; Calvagno, G.; Calvini, P.; Checchia, P.; Cortelazzo, G.; Cossutta, L.; Donzella, A.; Furlan, M.; Gonella, F.; Pegoraro, M.; Rigoni Garola, A.; Ronchese, P.; Squarcia, S.; Subieta, M.; Vanini, S.; Viesti, G.; Zanuttigh, P.; Zenoni, A.; Zumerle, G.

    2013-12-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented.

  1. Electromagnetic bandgap (EBG) structures common mode filters for high speed digital systems

    CERN Document Server

    Orlandi, Antonio; De Paulis, Francesco; Connor, Samuel

    2017-01-01

    Digital Services in the 21st Century provides a holistic approach to understanding telecommunications by addressing the emergence and dominance of new digital services, consumer and economic dynamics, and the creation of content by service providers. The authors cover the main products and services that are provided by telecommunications operators (in general information and communication technologies providers). Key topics discussed include enriched communications, fixed and mobile broadband, financial services for unbanked customers in emerging markets, Pay TV, data communications for machines, and digital home. As opposed to technical-driven textbooks, this book also addresses customer demand and the competitive nature between telecommunications operators and Internet providers that compete to provide compelling services.

  2. Adaptive iterated function systems filter for images highly corrupted with fixed - Value impulse noise

    Science.gov (United States)

    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.

  3. A HIGH STABILITY, LOW NOISE RF DISTRIBUTION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Noise calculation model and analysis of high-gain readout circuits for CMOS image sensors

    Science.gov (United States)

    Kawahito, Shoji; Itoh, Shinya

    2008-02-01

    A thermal noise calculation model of high-gain switched-capacitor column noise cancellers for CMOS image sensors is presented. In the high-gain noise canceller with a single noise cancelling stage, the reset noise of the readout circuits dominates the noise at high gain. Using the double-stage architecture using a switched-capacitor gain stage and a sample-and-hold stage using two sampling capacitors, the reset noise of the gain stage can be cancelled. The resulting input referred thermal noise power of high-gain double-stage switched-capacitor noise canceller is revealed to be proportional to (g_a/g_s)/GC_L where g_a, G and C_L are the transconductance, gain and output capacitance of the amplifier, respectively, and g_s is the output conductance of an in-pixel source follower. An important contribution of the proposed noise calculation formula is the inclusion of the influence of the transconductance ratio of the amplifier to that of the source follower. For low-noise design, it is important that the transconductance of the amplifier used in the noise canceller is minimized under the condition of meeting the required response time of the switched capacitor amplifier which is inversely proportional to the cutoff angular frequency.

  5. Quantum 1/f Noise in High Technology Applications Including Ultrasmall Structures and Devices

    Science.gov (United States)

    1992-07-14

    Noise in Physical Systems and III Int. Conf. on 1/f Noise, Montpellier, May 17-20, 1983, V.M. Savelli, G. Lecoy and J.P. Nougier Editors, North...Handel, ’Any Particle Represented by a Coherent State Exhibits 1/f Noise" in "Noise in Physical Systems and 1/f Noise’, edited by M. Savelli, G. Lecoy and...218-225. [491 M.B. Bloch, J.C. Ho, C.S. Stone , A. Syed and F.L Walls, "Stability of High Quality Quartz Crystal Oscillators: an Update", Proc. 43rd

  6. High Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Noise mitigation for subsonic transports is a continuing high priority, and recent work has identified successful exhaust mixing enhancement devices that have...

  7. High Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Noise mitigation for subsonic transports is a continuing high priority, and recent work has identified successful exhaust mixing enhancement devices (chevrons) that...

  8. Spatio-temporal filtering for determination of common mode error in regional GNSS networks

    Science.gov (United States)

    Bogusz, Janusz; Gruszczynski, Maciej; Figurski, Mariusz; Klos, Anna

    2015-04-01

    The spatial correlation between different stations for individual components in the regional GNSS networks seems to be significant. The mismodelling in satellite orbits, the Earth orientation parameters (EOP), largescale atmospheric effects or satellite antenna phase centre corrections can all cause the regionally correlated errors. This kind of GPS time series errors are referred to as common mode errors (CMEs). They are usually estimated with the regional spatial filtering, such as the "stacking". In this paper, we show the stacking approach for the set of ASG-EUPOS permanent stations, assuming that spatial distribution of the CME is uniform over the whole region of Poland (more than 600 km extent). The ASG-EUPOS is a multifunctional precise positioning system based on the reference network designed for Poland. We used a 5- year span time series (2008-2012) of daily solutions in the ITRF2008 from Bernese 5.0 processed by the Military University of Technology EPN Local Analysis Centre (MUT LAC). At the beginning of our analyses concerning spatial dependencies, the correlation coefficients between each pair of the stations in the GNSS network were calculated. This analysis shows that spatio-temporal behaviour of the GPS-derived time series is not purely random, but there is the evident uniform spatial response. In order to quantify the influence of filtering using CME, the norms L1 and L2 were determined. The values of these norms were calculated for the North, East and Up components twice: before performing the filtration and after stacking. The observed reduction of the L1 and L2 norms was up to 30% depending on the dimension of the network. However, the question how to define an optimal size of CME-analysed subnetwork remains unanswered in this research, due to the fact that our network is not extended enough.

  9. Study of the impact of board orientation on radiated emissions due to common-mode currents on attached cables

    DEFF Research Database (Denmark)

    Sørensen, Morten; Hubing, Todd H.; Jensen, Kim

    2016-01-01

    Common-mode current on attached cables is a typical source for radiated emission. Several models have been made for conversion of the intended differential signal to unwanted common-mode current on cables. In this paper we refine a method for identifying the radiation sources arising from a long...... microstrip. This method is used to show that the radiated emission from a PCB with attached cable(s) caused by a long trace depends on whether the trace is facing up or down with different result for voltage and current sources....

  10. Noise Reduction in High-Throughput Gene Perturbation Screens

    Science.gov (United States)

    Motivation: Accurate interpretation of perturbation screens is essential for a successful functional investigation. However, the screened phenotypes are often distorted by noise, and their analysis requires specialized statistical analysis tools. The number and scope of statistical methods available...

  11. Lung sounds auscultation technology based on ANC-ICA algorithm in high battlefield noise environment

    Institute of Scientific and Technical Information of China (English)

    牛海军; 冯安吉; 万明习; 白培瑞

    2003-01-01

    AIM:To explore the more accurate lung sounds auscultation technology in high battlefield noise environment.METHODS: In this study, we restrain high background noise using a new method-adaptive noise canceling based on independent component analysis (ANC-ICA), the method, by incorporating both second-order and higher-order statistics can remove noise components of the primary input signal based on statistical independence.RESULTS:The algorithm retained the local feature of lung sounds while eliminating high background noise, and performed more effectively than the conventional LMS algorithm.CONCLUSION:This method can cancel high battlefield noise of lung sounds effectively thus can help diagnose lung disease more accurately.

  12. Factors Affecting Noise Levels of High-Speed Handpieces

    Science.gov (United States)

    2012-06-01

    office communication and increase patient anxiety. Purpose: To determine if three noise-reducing techniques utilized in larger scale , non- dental...hearing loss may cause confusion, fear, and loneliness , and that sometimes hearing loss is accompanied by dizziness, which would be a handicap in the...employee noise exposures equal or exceed an 8- hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or

  13. Refraction of high frequency noise in an arbitrary jet flow

    Science.gov (United States)

    Khavaran, Abbas; Krejsa, Eugene A.

    1994-01-01

    Refraction of high frequency noise by mean flow gradients in a jet is studied using the ray-tracing methods of geometrical acoustics. Both the two-dimensional (2D) and three-dimensional (3D) formulations are considered. In the former case, the mean flow is assumed parallel and the governing propagation equations are described by a system of four first order ordinary differential equations. The 3D formulation, on the other hand, accounts for the jet spreading as well as the axial flow development. In this case, a system of six first order differential equations are solved to trace a ray from its source location to an observer in the far field. For subsonic jets with a small spreading angle both methods lead to similar results outside the zone of silence. However, with increasing jet speed the two prediction models diverge to the point where the parallel flow assumption is no longer justified. The Doppler factor of supersonic jets as influenced by the refraction effects is discussed and compared with the conventional modified Doppler factor.

  14. A genetically encoded, high-signal-to-noise maltose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Marvin, Jonathan S.; Schreiter, Eric R.; Echevarría, Ileabett M.; Looger, Loren L. (Puerto Rico); (HHMI)

    2012-10-23

    We describe the generation of a family of high-signal-to-noise single-wavelength genetically encoded indicators for maltose. This was achieved by insertion of circularly permuted fluorescent proteins into a bacterial periplasmic binding protein (PBP), Escherichia coli maltodextrin-binding protein, resulting in a four-color family of maltose indicators. The sensors were iteratively optimized to have sufficient brightness and maltose-dependent fluorescence increases for imaging, under both one- and two-photon illumination. We demonstrate that maltose affinity of the sensors can be tuned in a fashion largely independent of the fluorescent readout mechanism. Using literature mutations, the binding specificity could be altered to moderate sucrose preference, but with a significant loss of affinity. We use the soluble sensors in individual E. coli bacteria to observe rapid maltose transport across the plasma membrane, and membrane fusion versions of the sensors on mammalian cells to visualize the addition of maltose to extracellular media. The PBP superfamily includes scaffolds specific for a number of analytes whose visualization would be critical to the reverse engineering of complex systems such as neural networks, biosynthetic pathways, and signal transduction cascades. We expect the methodology outlined here to be useful in the development of indicators for many such analytes.

  15. Methodology for 1/f noise parameter extraction for high-voltage MOSFETs

    Science.gov (United States)

    Mavredakis, Nikolaos; Pflanzl, Walter; Seebacher, Ehrenfried; Bucher, Matthias

    2015-01-01

    This paper proposes a detailed low frequency noise (LFN) parameter extraction method for high-voltage (HV) MOSFETs at low (50 mV) and medium (3 V) drain biases. In Vd = 3 V region, noise coming from the channel is dominant while in linear region there is an extra contribution of noise from the drift region part especially for long-channel devices in strong inversion region. Flicker noise of 50 V and 20 V N- and P-channel HV-MOSFETs was measured over a large current range from weak to strong inversion, making possible the extraction of the noise parameters related to the different noise contributions, such as mobility fluctuations in low current regime, carrier number fluctuations and Coulomb scattering in medium and high current regime. In some cases, series resistance noise contribution especially at high current is apparent as well. The parameter extraction procedure is devised for a recently established charge-based flicker noise model for HV-MOSFETs. Noise parameters related to the carrier number fluctuation effect in the gate oxide extension in drift region are also extracted in high current regime of long-channel devices under low drain bias condition. The frequency exponent AF related to the slope of the measured noise spectra is also extracted. Measurements and analysis include both long as well as short N- and P-channel HV-MOSFETs.

  16. High Speed Research Noise Prediction Code (HSRNOISE) User's and Theoretical Manual

    Science.gov (United States)

    Golub, Robert (Technical Monitor); Rawls, John W., Jr.; Yeager, Jessie C.

    2004-01-01

    This report describes a computer program, HSRNOISE, that predicts noise levels for a supersonic aircraft powered by mixed flow turbofan engines with rectangular mixer-ejector nozzles. It fully documents the noise prediction algorithms, provides instructions for executing the HSRNOISE code, and provides predicted noise levels for the High Speed Research (HSR) program Technology Concept (TC) aircraft. The component source noise prediction algorithms were developed jointly by Boeing, General Electric Aircraft Engines (GEAE), NASA and Pratt & Whitney during the course of the NASA HSR program. Modern Technologies Corporation developed an alternative mixer ejector jet noise prediction method under contract to GEAE that has also been incorporated into the HSRNOISE prediction code. Algorithms for determining propagation effects and calculating noise metrics were taken from the NASA Aircraft Noise Prediction Program.

  17. Noise in a coupling electromagnetic detecting system for high frequency gravitational waves

    Institute of Scientific and Technical Information of China (English)

    Li Jin; Li Fang-Yu; Zhong Yuan-Hong

    2009-01-01

    This paper discusses the basic categories of noise in detecting high frequency gravitational waves in the microwave band (~0.1-10 GHz), which contain shot noise from the laser and the thermal radiation photons, thermal noise from statistical fluctuation of the thermal photons and fluctuation of the temperature, radiation press noise on the fractal membrane, the noise caused by the scattering of the Gaussian Beam (GB) in the detecting tube and noise in the microwave radiometers. The analysis shows that a reasonable signal-to-noise ratio may be achieved for a detecting device with the fixed power of GB (105 W), only when the temperature of the environment is no more than T=l K, and the optimal length of the microwave radiometers is about 0.3 m.

  18. CT urography in the urinary bladder: To compare excretory phase images using a low noise index and a high noise index with adaptive noise reduction filter

    Energy Technology Data Exchange (ETDEWEB)

    Takeyama, Nobuyuki; Hayashi, Takaki (Dept. of Radiology, Showa Univ. Fujigaoka Hospital, Yokohama (Japan)), email: momiji@mtc.biglobe.ne.jp; Ohgiya, Yoshimitsu (Dept. of Radiology, Showa Univ. School of Medicine, Tokyo (Japan)) (and others)

    2011-07-15

    Background: Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure. Purpose: To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF). Material and Methods: Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDI{sub vol}) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale. Results: The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDI{sub vol} demonstrated a 73% reduction in group B (4.6 +- 1.1 mGy) compared with group A (16.9 +- 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 +- 5.1) and group B (16.6 +- 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences. Conclusion: EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise

  19. Design of noise barrier inspection system for high-speed railway

    Science.gov (United States)

    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.

  20. Noise estimation Algorithms for Speech Enhancement in highly non-stationary Environments

    Directory of Open Access Journals (Sweden)

    Anuradha R Fukane

    2011-03-01

    Full Text Available A noise estimation algorithm plays an important role in speech enhancement. Speech enhancement for automatic speaker recognition system, Man-Machine communication, Voice recognition systems, speech coders, Hearing aids, Video conferencing and many applications are related to speech processing. All these systems are real world systems and input available for these systems is only the noisy speech signal, before applying to these systems we have to remove the noise component from noisy speech signal means enhanced speech signal can be applied to these systems. In most speech enhancement algorithms, it is assumed that an estimate of noise spectrum is available. Noise estimate is critical part and it is important for speech enhancement algorithms. If the noise estimate is too low then annoying residual noise will be available and if the noise estimate is too high then speech will get distorted and loss intelligibility. This paper focus on the different approaches of noise estimation. Section I introduction, Section II explains simple approach of Voice activity detector (VAD for noise estimation, Section III explains different classes of noise estimation algorithms, Section IV explains performance evaluation of noise estimation algorithms, Section V conclusion.

  1. Compact design of a planar filtering antenna array including a frequency selective common-mode rejection module

    NARCIS (Netherlands)

    Cifola, L.; Cavallo, D.; Gerini, G.; Morini, A.

    2012-01-01

    A new compact design of a planar phased-array antenna with inherent frequency selectivity properties is presented. In previous works, starting from an array of connected dipoles, the design of a filtenna structure and a strategy for the suppression of common-mode resonances have been addressed. In t

  2. Correlation of Electrical Noise with Non-radiative Current for High Power QWLs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The characteristics of low-frequency electrical noise, voltage-current (V-I) and electrical derivation for 980nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditions. The correlation of the low-frequency electrical noise with surface non-radiative current of devices is discussed. The results indicate the low-frequency electrical noise of 980nm DQWLs with high power is mainly 1/f noise and has good relation with the device surface current at low injection.

  3. Noise reduction of high-power supercontinuum sources by back seeding

    DEFF Research Database (Denmark)

    Moselund, Peter Morten; Frosz, Michael Henoch; Thomsen, Carsten L.

    2009-01-01

    We investigate noise reduction in seeded supercontinuum generation at powers above the supercontinuum generation threshold and show that seeding of supercontinuum is also beneficial at high pump powers.......We investigate noise reduction in seeded supercontinuum generation at powers above the supercontinuum generation threshold and show that seeding of supercontinuum is also beneficial at high pump powers....

  4. Evaluation and Analysis of Noise Level at High-Traffic Locations in Gusau, Nigeria

    Directory of Open Access Journals (Sweden)

    Jacob O. Ebozoje

    2013-12-01

    Full Text Available The measurement of noise levels at high-traffic intersections of Gusau town is reported in this work. Five high-traffic locations tagged LOC-A, LOC-B, LOC-C, LOC-D and LOC-E were selected and evaluated at different periods of the day using an MS6700 IEC 651, ANSI.Si.4 Type-2 Sound Level meter. Result analyses indicates that LOC-C has the highest noise level with LNP = 95 and TNI = 94, while LOC-B has the lowest noise level with LNP = 82 and TNI = 67. These noise levels imply that Gusau metropolis has an unacceptable noise level, well above the globally recommended levels of 60-65 dB(A and the national recommended level of 82 dB(A. The paper therefore makes recommendations on minimizing these intolerable noise levels with consequences for environmental and human health in the study location.

  5. High Temperature Supersonic Jet Noise - Fundamental Studies and Control using Advanced Actuation Methods

    Science.gov (United States)

    2016-08-24

    decades, however methods of measurably controlling -reducing jet noise in an efficient and robust manner remain evasive. Previous research has shown...2016 1-May-2013 30-Apr-2016 High Temperature Supersonic Jet Noise - Fundamental Studies and Control using Advanced Actuation Methods The views...and Control using Advanced Actuation Methods Report Title Understanding and controlling jet noise has been the focus of analytical, computational and

  6. Model of small-scale self-focusing and spatial noise in high power laser driver

    Institute of Scientific and Technical Information of China (English)

    HU; Wei(胡巍); FU; Xiquan(傅喜泉); YU; Song; (喻松); GUO; Hong(郭弘)

    2002-01-01

    A linearization model was used to analyze the laser beam propagation in a high power laser driver and the influence of the small-scale self-focusing and spatial phase noise on beam quality in disk amplifiers. The quantitative relations between intensities of spatial phase noise, B-integral, and beam intensity contrast in near field are given explicitly. A spectrum specification of phase noise has been obtained by setting a limit to the contrast of an output beam.

  7. High temperature sensor/microphone development for active noise control

    Science.gov (United States)

    Shrout, Thomas R.

    1993-01-01

    The industrial and scientific communities have shown genuine interest in electronic systems which can operate at high temperatures, among which are sensors to monitor noise, vibration, and acoustic emissions. Acoustic sensing can be accomplished by a wide variety of commercially available devices, including: simple piezoelectric sensors, accelerometers, strain gauges, proximity sensors, and fiber optics. Of the several sensing mechanisms investigated, piezoelectrics were found to be the most prevalent, because of their simplicity of design and application and, because of their high sensitivity over broad ranges of frequencies and temperature. Numerous piezoelectric materials are used in acoustic sensors today; but maximum use temperatures are imposed by their transition temperatures (T(sub c)) and by their resistivity. Lithium niobate, in single crystal form, has the highest operating temperature of any commercially available material, 650 C; but that is not high enough for future requirements. Only two piezoelectric materials show potential for use at 1000 C; AlN thin film reported to be piezoactive at 1150 C, and perovskite layer structure (PLS) materials, which possess among the highest T(sub c) (greater than 1500 C) reported for ferroelectrics. A ceramic PLS composition was chosen. The solid solution composition, 80% strontium niobate (SN) and 20% strontium tantalate (STa), with a T(sub c) approximately 1160 C, was hot forged, a process which concurrently sinters and renders the plate-like grains into a highly oriented configuration to enhance piezo properties. Poled samples of this composition showed coupling (k33) approximately 6 and piezoelectric strain constant (d33) approximately 3. Piezoactivity was seen at 1125 C, the highest temperature measurement reported for a ferroelectric ceramic. The high temperature piezoelectric responses of this, and similar PLS materials, opens the possibility of their use in electronic devices operating at temperatures up to

  8. Method of recognizing the high-speed railway noise barriers based on the distance image

    Science.gov (United States)

    Ma, Le; Shao, Shuangyun; Feng, Qibo; Liu, Bingqian; Kim, Chol Ryong

    2016-10-01

    The damage or lack of the noise barriers is one of the important hidden troubles endangering the safety of high-speed railway. In order to obtain the vibration information of the noise barriers, the online detection systems based on laser vision were proposed. The systems capture images of the laser stripe on the noise barriers and export data files containing distance information between the detection systems on the train and the noise barriers. The vibration status or damage of the noise barriers can be estimated depending on the distance information. In this paper, we focused on the method of separating the area of noise barrier from the background automatically. The test results showed that the proposed method is in good efficiency and accuracy.

  9. High Order Wavelet-Based Multiresolution Technology for Airframe Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a novel, high-accuracy, high-fidelity, multiresolution (MRES), wavelet-based framework for efficient prediction of airframe noise sources and...

  10. Design and evaluation of modelocked semiconductor lasers for low noise and high stability

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin;

    2005-01-01

    We present work on design of monolithic mode-locked semiconductor lasers with focus on the gain medium. The use of highly inverted quantum wells in a low-loss waveguide enables both low quantum noise, low-chirped pulses and a large stability region. Broadband noise measurements are performed...

  11. High phase noise tolerant pilot-tone-aided DP-QPSK optical communication systems

    DEFF Research Database (Denmark)

    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...

  12. Theoretical analysis of quantum dot amplifiers with high saturation power and low noise figure

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2002-01-01

    Semiconductor quantum dot amplifiers are predicted to exhibit superior characteristics such as high gain, and output power and low noise. The analysis provides criteria and design guidelines for the realization of high quality amplifiers.......Semiconductor quantum dot amplifiers are predicted to exhibit superior characteristics such as high gain, and output power and low noise. The analysis provides criteria and design guidelines for the realization of high quality amplifiers....

  13. Ground-roll noise extraction and suppression using high-resolution linear Radon transform

    Science.gov (United States)

    Hu, Yue; Wang, Limin; Cheng, Feng; Luo, Yinhe; Shen, Chao; Mi, Binbin

    2016-05-01

    Ground-roll is a main type of strong noises in petroleum seismic exploration. Suppression of this kind of noise is essential to improve the signal-to-noise ratio of seismic data. In the time-offset (t-x) domain, the ground-roll noise and the effective waves (e.g., direct waves, reflections) overlap with each other in terms of time and frequency, which make it difficult to suppress ground roll noise in exploration seismic data. However, significant different features shown in the frequency-velocity (f-v) domain make it possible to separate ground roll noise and effective waves effectively. We propose a novel method to separate them using high-resolution linear Radon transform (LRT). Amplitude and phase information is preserved during the proposed quasi-reversible transformation. The reversibility and linearity of LRT provide a foundation for ground-roll noise suppression in the f-v domain. We extract the energy of ground-roll noise in the f-v domain, and transform the extracted part back to the t-x domain to obtain the ground-roll noise shot gather. Finally, the extracted ground-roll noise is subtracted from the original data arithmetically. Theoretical tests and a real world example have been implemented to illustrate that the ground-roll noise suppression can be achieved with negligible distortion of the effective signals. When compared with the adaptive ground-roll attenuation method and the K-L transform method, the real world example shows the superiority of our method in suppressing the ground-roll noise and preserving the amplitude and phase information of effective waves.

  14. Flicker noise in high-speed p-i-n photodiodes

    CERN Document Server

    Rubiola, E; Yu, N; Maleki, L; Rubiola, Enrico; Salik, Ertan; Yu, Nan; Maleki, Lute

    2005-01-01

    The microwave signal at the output of a photodiode that detects a modulated optical beam contains the phase noise phi(t) and the amplitude noise alpha(t) of the detector. Beside the white noise, which is well understood, the spectral densities S_phi(f) and S_alpha(f) show flicker noise, proportional to 1/f. We report on the measurement of the phase and amplitude noise of high-speed p-i-n photodiodes. The main result is that the flicker coefficient of the samples is approximately 1E-12 rad^2/Hz (-120dB) for phase noise, and approximately 1E-12 Hz^-1 (-120dB) for amplitude noise. These values could be observed only after solving a number of experimental problems and in a protected environment. By contrast, in ordinary conditions insufficient EMI isolation, and also insufficient mechanical isolation, are responsible for additional noise to be taken in. This suggests that if package and EMC are revisited, applications can take the full benefit from the surprisingly low noise of the p-i-n photodiodes.

  15. High-speed helicopter rotor noise - Shock waves as a potent source of sound

    Science.gov (United States)

    Farassat, F.; Lee, Yung-Jang; Tadghighi, H.; Holz, R.

    1991-01-01

    In this paper we discuss the problem of high speed rotor noise prediction. In particular, we propose that from the point of view of the acoustic analogy, shocks around rotating blades are sources of sound. We show that, although for a wing at uniform steady rectilinear motion with shocks the volume quadrupole and shock sources cancel in the far field to the order of 1/r, this cannot happen for rotating blades. In this case, some cancellation between volume quadrupoles and shock sources occurs, yet the remaining shock noise contribution is still potent. A formula for shock noise prediction is presented based on mapping the deformable shock surface to a time independent region. The resulting equation is similar to Formulation 1A of Langley. Shock noise prediction for a hovering model rotor for which experimental noise data exist is presented. The comparison of measured and predicted acoustic data shows good agreement.

  16. Comparative Studies on Low Noise Greases Operating under High Temperature Oxidation Conditions

    Institute of Scientific and Technical Information of China (English)

    Xiong Chunhua; Mi Hongying; Feng Qiang; Wu Baojie

    2014-01-01

    Oxidation induction time (OIT) testing by differential scanning calorimetry (DSC) was used to evaluate the oxidation resistance of lubricating greases. Under the high temperature condition, bearing noise was detected when grease passed the initial stable stage of oxidation. The chemical and physical structure of grease samples before and after high tem-perature oxidation were also analyzed by FT-IR spectrometry and scanning electron microscopy (SEM), then the effects of oxidation at high temperature on bearing noise were investigated. It is found out that for lithium greases, oxidation of base oil and thickener is the main reason responsible for the increasing bearing noise. As regards the polyurea greases, the change of ifber microstructure at high temperature is the main reason for the increasing bearing noise.

  17. Very High Gain and Low Noise Near Infrared Single Photon Counting Detectors and Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Amplification Technologies Inc ("ATI") proposes to develop the enabling material and device technology for the design of ultra low noise, high gain and low...

  18. Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Voxtel Inc. proposes to optimize the design of a large area, 1.55?m sensitive HgCdTe avalanche photodiode (APD) that achieves high gain with nearly no excess noise....

  19. High Order Wavelet-Based Multiresolution Technology for Airframe Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An integrated framework is proposed for efficient prediction of rotorcraft and airframe noise. A novel wavelet-based multiresolution technique and high-order...

  20. High Pressure Air Jet in the Endoscopic Preparation Room: Risk of Noise Exposure on Occupational Health

    OpenAIRE

    King-Wah Chiu; Lung-Sheng Lu; Cheng-Kun Wu

    2015-01-01

    After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment w...

  1. 1/f noise in forward biased high voltage 4H-SiC Schottky diodes

    Science.gov (United States)

    Shabunina, Eugenia I.; Levinshtein, Michael E.; Shmidt, Natalia M.; Ivanov, Pavel A.; Palmour, John W.

    2014-06-01

    The 1/f noise has been investigated for the first time at 300 and 77 K in high-quality 4H-SiC Schottky diodes. It is shown that, at 77 K, the dependence of the spectral noise density on current, SI(I), differs fundamentally between the cases of the current flowing through the main part of the diode with a comparatively high barrier and the current flowing through the nano-sized patches with a comparatively low barrier.

  2. High Resolution Viscosity Measurement by Thermal Noise Detection

    Directory of Open Access Journals (Sweden)

    Felipe Aguilar Sandoval

    2015-11-01

    Full Text Available An interferometric method is implemented in order to accurately assess the thermal fluctuations of a micro-cantilever sensor in liquid environments. The power spectrum density (PSD of thermal fluctuations together with Sader’s model of the cantilever allow for the indirect measurement of the liquid viscosity with good accuracy. The good quality of the deflection signal and the characteristic low noise of the instrument allow for the detection and corrections of drawbacks due to both the cantilever shape irregularities and the uncertainties on the position of the laser spot at the fluctuating end of the cantilever. Variation of viscosity below 0.03 mPa·s was detected with the alternative to achieve measurements with a volume as low as 50 µL.

  3. Development of low read noise high conversion gain CMOS image sensor for photon counting level imaging

    Science.gov (United States)

    Seo, Min-Woong; Kawahito, Shoji; Kagawa, Keiichiro; Yasutomi, Keita

    2016-05-01

    A CMOS image sensor with deep sub-electron read noise and high pixel conversion gain has been developed. Its performance is recognized through image outputs from an area image sensor, confirming the capability of photoelectroncounting- level imaging. To achieve high conversion gain, the proposed pixel has special structures to reduce the parasitic capacitances around FD node. As a result, the pixel conversion gain is increased due to the optimized FD node capacitance, and the noise performance is also improved by removing two noise sources from power supply. For the first time, high contrast images from the reset-gate-less CMOS image sensor, with less than 0.3e- rms noise level, have been generated at an extremely low light level of a few electrons per pixel. In addition, the photon-counting capability of the developed CMOS imager is demonstrated by a measurement, photoelectron-counting histogram (PCH).

  4. Electro-optic comb based real time ultra-high sensitivity phase noise measurement system for high frequency microwaves.

    Science.gov (United States)

    Kuse, N; Fermann, M E

    2017-06-06

    Recent progress in ultra low phase noise microwave generation indispensably depends on ultra low phase noise characterization systems. However, achieving high sensitivity currently relies on time consuming averaging via cross correlation, which sometimes even underestimates phase noise because of residual correlations. Moreover, extending high sensitivity phase noise measurements to microwaves beyond 10 GHz is very difficult because of the lack of suitable high frequency microwave components. In this work, we introduce a delayed self-heterodyne method in conjunction with sensitivity enhancement via the use of higher order comb modes from an electro-optic comb for ultra-high sensitivity phase noise measurements. The method obviates the need for any high frequency RF components and has a frequency measurement range limited only by the bandwidth (100 GHz) of current electro-optic modulators. The estimated noise floor is as low as -133 dBc/Hz, -155 dBc/Hz, -170 dBc/Hz and -171 dBc/Hz without cross correlation at 1 kHz, 10 kHz, 100 kHz and 1 MHz Fourier offset frequency for a 10 GHz carrier, respectively. Moreover, since no cross correlation is necessary, RF oscillator phase noise can be directly suppressed via feedback up to 100 kHz frequency offset.

  5. MEMS microphone innovations towards high signal to noise ratios (Conference Presentation) (Plenary Presentation)

    Science.gov (United States)

    Dehé, Alfons

    2017-06-01

    After decades of research and more than ten years of successful production in very high volumes Silicon MEMS microphones are mature and unbeatable in form factor and robustness. Audio applications such as video, noise cancellation and speech recognition are key differentiators in smart phones. Microphones with low self-noise enable those functions. Backplate-free microphones enter the signal to noise ratios above 70dB(A). This talk will describe state of the art MEMS technology of Infineon Technologies. An outlook on future technologies such as the comb sensor microphone will be given.

  6. A new behavioural model for performance evaluation of common mode chokes

    NARCIS (Netherlands)

    Roc'h, A.; Bergsma, H.; Zhao, D.; Ferreira, B.; Leferink, F.B.J.

    2007-01-01

    A galvanically isolated three-phase AC/AC converter with a high-frequency AC-link has been analyzed from an EMC point of view. This is a special configuration because of a large number of switches, a high frequency transformer, and a fourwire output. The essential coupling paths are identified. Corr

  7. Jet noise of high aspect-ratio rectangular nozzles with application to pneumatic high-lift devices

    Science.gov (United States)

    Munro, Scott Edward

    Circulation control wings are a type of pneumatic high-lift device that have been extensively researched as to their aerodynamic benefits. However, there has been little research into the possible airframe noise reduction benefits. The key element of noise is the jet noise associated with the jet sheet emitted from the blowing slot. This jet sheet is essentially a high aspect-ratio rectangular jet. This study directly compared far-field noise emissions from a state-of-the-art circulation control wing high lift configuration, and a conventional wing also configured for high lift. Results indicated that a circulation control wing had a significant acoustic advantage over a conventional wing for identical lift performance. A high aspect-ratio nozzle was fabricated to study the general characteristics of high aspect-ratio jets with aspect ratios from 100 to 3000. The results of this study provided the basic elements in understanding how to reduce the noise from a circulation control wing. High aspect-ratio nozzle results showed that the jet noise of this type of jet was proportional to the 8th power of the jet velocity. It was also found that the jet noise was proportional to the slot height to the 3/2 power and slot width to the 1/2 power. Fluid dynamic experiments were also performed on the high aspect-ratio nozzle. Single hot-wire experiments indicated that the jet exhaust from the high aspect-ratio nozzle was similar to a 2-d turbulent jet. Two-wire space-correlation experiments were performed to attempt to find a relationship between the slot height of the jet and the length-scale of the flow noise generating turbulence structure. The turbulent eddy convection velocity was also calculated, and was found to vary with the local centerline velocity, and also as a function of the frequency of the eddy.

  8. High-order noise analysis for low dose iterative image reconstruction methods: ASIR, IRIS, and MBAI

    Science.gov (United States)

    Do, Synho; Singh, Sarabjeet; Kalra, Mannudeep K.; Karl, W. Clem; Brady, Thomas J.; Pien, Homer

    2011-03-01

    Iterative reconstruction techniques (IRTs) has been shown to suppress noise significantly in low dose CT imaging. However, medical doctors hesitate to accept this new technology because visual impression of IRT images are different from full-dose filtered back-projection (FBP) images. Most common noise measurements such as the mean and standard deviation of homogeneous region in the image that do not provide sufficient characterization of noise statistics when probability density function becomes non-Gaussian. In this study, we measure L-moments of intensity values of images acquired at 10% of normal dose and reconstructed by IRT methods of two state-of-art clinical scanners (i.e., GE HDCT and Siemens DSCT flash) by keeping dosage level identical to each other. The high- and low-dose scans (i.e., 10% of high dose) were acquired from each scanner and L-moments of noise patches were calculated for the comparison.

  9. Design and validation of the high performance and low noise CQU-DTU-LN1 airfoils

    DEFF Research Database (Denmark)

    Cheng, Jiangtao; Zhu, Wei Jun; Fischer, Andreas

    2014-01-01

    with the blade element momentum theory, the viscous-inviscid XFOIL code and an airfoil self-noise prediction model, an optimization algorithm has been developed for designing the high performance and low noise CQU-DTU-LN1 series of airfoils with targets of maximum power coefficient and low noise emission......This paper presents the design and validation of the high performance and low noise Chong Qing University and Technical University of Denmark LN1 (CQU-DTU-LN1) series of airfoils for wind turbine applications. The new design method uses target characteristics of wind turbine airfoils in the design...... emission between the CQU-DTU-LN118 airfoil and the National Advisory Committee for Aeronautics (NACA) 64618 airfoil, which is used in modern wind turbine blades, are carried out. Copyright © 2013 John Wiley & Sons, Ltd....

  10. Coherent Dual Comb Spectroscopy at High Signal to Noise

    CERN Document Server

    Coddington, I; Newbury, N R

    2010-01-01

    Two frequency combs can be used to measure the full complex response of a sample in a configuration which can be alternatively viewed as the equivalent of a dispersive Fourier transform spectrometer, infrared time domain spectrometer, or a multiheterodyne laser spectrometer. This dual comb spectrometer retains the frequency accuracy and resolution inherent to the comb sources. We discuss, in detail, the specific design of our coherent dual-comb spectrometer and demonstrate the potential of this technique by measuring the first overtone vibration of hydrogen cyanide, centered at 194 THz (1545 nm). We measure the fully normalized, complex response of the gas over a 9 THz bandwidth at 220 MHz frequency resolution yielding 41,000 resolution elements. The average spectral signal-to-noise ratio (SNR) is 2,500 for both the fractional absorption and the phase, with a peak SNR of 4,000 corresponding to a fractional absorption sensitivity of 0.025% and phase sensitivity of 250 microradians. As the spectral coverage of ...

  11. High-frequency audiometry: A means for early diagnosis of noise-induced hearing loss

    OpenAIRE

    Amir H Mehrparvar; Seyyed J Mirmohammadi; Abbas Ghoreyshi; Abolfazl Mollasadeghi; Ziba Loukzadeh

    2011-01-01

    Noise-induced hearing loss (NIHL), an irreversible disorder, is a common problem in industrial settings. Early diagnosis of NIHL can help prevent the progression of hearing loss, especially in speech frequencies. For early diagnosis of NIHL, audiometry is performed routinely in conventional frequencies. We designed this study to compare the effect of noise on high-frequency audiometry (HFA) and conventional audiometry. In a historical cohort study, we compared hearing threshold and prevalence...

  12. Component-based model to predict aerodynamic noise from high-speed train pantographs

    Science.gov (United States)

    Latorre Iglesias, E.; Thompson, D. J.; Smith, M. G.

    2017-04-01

    At typical speeds of modern high-speed trains the aerodynamic noise produced by the airflow over the pantograph is a significant source of noise. Although numerical models can be used to predict this they are still very computationally intensive. A semi-empirical component-based prediction model is proposed to predict the aerodynamic noise from train pantographs. The pantograph is approximated as an assembly of cylinders and bars with particular cross-sections. An empirical database is used to obtain the coefficients of the model to account for various factors: incident flow speed, diameter, cross-sectional shape, yaw angle, rounded edges, length-to-width ratio, incoming turbulence and directivity. The overall noise from the pantograph is obtained as the incoherent sum of the predicted noise from the different pantograph struts. The model is validated using available wind tunnel noise measurements of two full-size pantographs. The results show the potential of the semi-empirical model to be used as a rapid tool to predict aerodynamic noise from train pantographs.

  13. Minimum Climb to Cruise Noise Trajectories Modeled for the High Speed Civil Transport

    Science.gov (United States)

    Berton, Jeffrey J.

    1998-01-01

    The proposed U.S. High Speed Civil Transport (HSCT) will revolutionize commercial air travel by providing economical supersonic passenger service to destinations worldwide. Unlike the high-bypass turbofan engines that propel today's subsonic airliners, HSCT engines will have much higher jet exhaust speeds. Jet noise, caused by the turbulent mixing of high-speed exhaust with the surrounding air, poses a significant challenge for HSCT engine designers. To resolve this challenge, engineers have designed advanced mixer rejector nozzles that reduce HSCT jet noise to airport noise certification levels by entraining and mixing large quantities of ambient air with the engines' jet streams. Although this works well during the first several minutes of flight, far away from the airport, as the HSCT gains speed and climbs, poor ejector inlet recovery and ejector ram drag contribute to poor thrust, making it advantageous to turn off the ejector. Doing so prematurely, however, can cause unacceptable noise levels to propagate to the ground, even when the aircraft is many miles from the airport. This situation lends itself ideally to optimization, where the aircraft trajectory, throttle setting, and ejector setting can be varied (subject to practical aircraft constraints) to minimize the noise propagated to the ground. A method was developed at the NASA Lewis Research Center that employs a variation of the classic energy state approximation: a trajectory analysis technique historically used to minimize climb time or fuel burned in many aircraft problems. To minimize the noise on the ground at any given throttle setting, high aircraft altitudes are desirable; but the HSCT may either climb quickly to high altitudes using a high, noisy throttle setting or climb more slowly at a lower, quieter throttle setting. An optimizer has been programmed into NASA's existing aircraft and noise analysis codes to balance these options by dynamically choosing the best altitude-velocity path and

  14. A novel SWIR detector with an ultra-high internal gain and negligible excess noise

    Science.gov (United States)

    Mohseni, H.; Memis, O. G.; Kong, S. C.; Katsnelson, A.; Wu, W.

    2007-10-01

    Short wave infrared (SWIR) imaging systems have several advantages due to the spectral content of the nightglow and better discrimination against camouflage. Achieving single photon detection sensitivity can significantly improve the image quality of these systems. However, the internal noise of the detector and readout circuits are significant barriers to achieve this goal. One can prove that the noise limitations of the readout can be alleviated, if the detector exhibits sufficiently high internal gain. Unfortunately, the existing detectors with internal gain have a very high noise as well. Here we present the recent results from our novel FOcalized Carrier aUgmented Sensor (FOCUS). It utilizes very high charge compression into a nano-injector, and subsequent carrier injection to achieve high quantum efficiency and high sensitivity at short infrared at room temperature. We obtain internal gain values exceeding several thousand at bias values of less than 1 volt. The current responsivity at 1.55 μm is more than 1500 A/W, and the noise equivalent power (NEP) is less that 0.5 x10 -15 W/Hz 1/2 at room temperature. These are significantly better than the performance of the existing room temperature devices with internal gain. Also, unlike avalanche-based photodiodes, the measured excess noise factor for our device is near unity, even at very high gain values. The stable gain of the device combined with the low operating voltage are unique advantages of this technology for high-performance SWIR imaging arrays.

  15. Surrogate Based Optimization of Aerodynamic Noise for Streamlined Shape of High Speed Trains

    Directory of Open Access Journals (Sweden)

    Zhenxu Sun

    2017-02-01

    Full Text Available Aerodynamic noise increases with the sixth power of the running speed. As the speed increases, aerodynamic noise becomes predominant and begins to be the main noise source at a certain high speed. As a result, aerodynamic noise has to be focused on when designing new high-speed trains. In order to perform the aerodynamic noise optimization, the equivalent continuous sound pressure level (SPL has been used in the present paper, which could take all of the far field observation probes into consideration. The Non-Linear Acoustics Solver (NLAS approach has been utilized for acoustic calculation. With the use of Kriging surrogate model, a multi-objective optimization of the streamlined shape of high-speed trains has been performed, which takes the noise level in the far field and the drag of the whole train as the objectives. To efficiently construct the Kriging model, the cross validation approach has been adopted. Optimization results reveal that both the equivalent continuous sound pressure level and the drag of the whole train are reduced in a certain extent.

  16. Calculation Model for the Propagation of Audible Noise from High Voltage Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    LI Xuebao; CUI Xiang; LU Tiebing; HE Jiamei

    2013-01-01

    Audible noise from high voltage transmission lines' corona discharge has become one of the decisive factors affecting design of high voltage transmission lines,thus it is very important to study the spatial propagation characteristics of audible noise for its accurate prediction.A calculation model for the propagation of audible noise is presented in this paper,which is based on the basic equation of the sound wave and can involve the influences of the atmosphere absorption and ground effects.The effects of different ground impedances and the atmospheric attenuation on the distribution of sound pressure level are discussed in this paper.The results show that the atmospheric absorption may increase the attenuation of the audible noise,and the ground surface affects both the amplitude and phase of the sound.The spatial distribution fluctuates considering the ground effects.The atmospheric attenuation and the ground effect are closely related to the frequency of the noise.In the frequency range of the audible noise,the influence of atmospheric attenuation on the spatial propagation characteristics is more obvious in high frequency while ground has significant influences in low frequency.

  17. High Bypass Ratio Jet Noise Reduction and Installation Effects Including Shielding Effectiveness

    Science.gov (United States)

    Thomas, Russell H.; Czech, Michael J.; Doty, Michael J.

    2013-01-01

    An experimental investigation was performed to study the propulsion airframe aeroacoustic installation effects of a separate flow jet nozzle with a Hybrid Wing Body aircraft configuration where the engine is installed above the wing. Prior understanding of the jet noise shielding effectiveness was extended to a bypass ratio ten application as a function of nozzle configuration, chevron type, axial spacing, and installation effects from additional airframe components. Chevron types included fan chevrons that are uniform circumferentially around the fan nozzle and T-fan type chevrons that are asymmetrical circumferentially. In isolated testing without a pylon, uniform chevrons compared to T-fan chevrons showed slightly more low frequency reduction offset by more high frequency increase. Phased array localization shows that at this bypass ratio chevrons still move peak jet noise source locations upstream but not to nearly the extent, as a function of frequency, as for lower bypass ratio jets. For baseline nozzles without chevrons, the basic pylon effect has been greatly reduced compared to that seen for lower bypass ratio jets. Compared to Tfan chevrons without a pylon, the combination with a standard pylon results in more high frequency noise increase and an overall higher noise level. Shielded by an airframe surface 2.17 fan diameters from nozzle to airframe trailing edge, the T-fan chevron nozzle can produce reductions in jet noise of as much as 8 dB at high frequencies and upstream angles. Noise reduction from shielding decreases with decreasing frequency and with increasing angle from the jet inlet. Beyond an angle of 130 degrees there is almost no noise reduction from shielding. Increasing chevron immersion more than what is already an aggressive design is not advantageous for noise reduction. The addition of airframe control surfaces, including vertical stabilizers and elevon deflection, showed only a small overall impact. Based on the test results, the best

  18. The current-voltage and noise properties of high temperature superconductor SNS and grain boundary junctions

    CERN Document Server

    McGordon, A

    1999-01-01

    transport that was dominated by the interlayer material, but supercurrent transport that could be due to pinhole shorts. In addition, both geometries, especially the sandwich junction, showed large amounts of normal state noise making these junctions unsuitable for device applications. The effect of shining laser light onto a junction was investigated. The effects on the I-V characteristic were unobservable with the experimental resolution available. The effect of the light on the critical current noise of the junction was to reduce the noise peak slightly when compared to the unilluminated case- the reduction was of the order of 10%, comparable with experimental resolution. The study of the noise from Josephson Junctions is an intense field of research. Despite this, no clear picture of the current transport in these devices has emerged. Without the detailed understanding of the mechanisms of current transport in High Temperature Superconductor junctions, the design of superconducting electronics will not mo...

  19. Optimum Climb to Cruise Noise Trajectories for the High Speed Civil Transport

    Science.gov (United States)

    Berton, Jeffrey J.

    2003-01-01

    By entraining large quantities of ambient air into advanced ejector nozzles, the jet noise of the proposed High Speed Civil Transport (HSCT) is expected to be reduced to levels acceptable for airport-vicinity noise certification. Away from the airport, however, this entrained air is shut off and the engines are powered up from their cutback levels to provide better thrust for the climb to cruise altitude. Unsuppressed jet noise levels propagating to the ground far from the airport are expected to be high. Complicating this problem is the HSCT's relative noise level with respect to the subsonic commercial fleet of 2010, which is expected to be much quieter than it is today after the retirement of older, louder, domestic stage II aircraft by the year 2000. In this study, the classic energy state approximation theory is extended to calculate trajectories that minimize the climb to cruise noise of the HSCT. The optimizer dynamically chooses the optimal altitude velocity trajectory, the engine power setting, and whether the ejector should be stowed or deployed with respect to practical aircraft climb constraints and noise limits.

  20. High Density Impulse Noise Detection using Fuzzy C-means Algorithm

    Directory of Open Access Journals (Sweden)

    Isha Singh

    2016-01-01

    Full Text Available A new technique for detecting the high density impulse noise from corrupted images using Fuzzy C-means algorithm is proposed. The algorithm is iterative in nature and preserves more image details in high noise environment. Fuzzy C-means is initially used to cluster the image data. The application of Fuzzy C-means algorithm in the detection phase provides an optimum classification of noisy data and uncorrupted image data so that the pictorial information remains well preserved. Experimental results show that the proposed algorithm significantly outperforms existing well-known techniques. Results show that with the increase in percentage of noise density, the performance of the algorithm is not degraded. Furthermore, the varying window size in the two detection stages provides more efficient results in terms of low false alarm rate and miss detection rate. The simple structure of the algorithm to detect impulse noise makes it useful for various applications like satellite imaging, remote sensing, medical imaging diagnosis and military survillance. After the efficient detection of noise, the existing filtering techniques can be used for the removal of noise.Defence Science Journal, Vol. 66, No. 1, January 2016, pp. 30-36, DOI: http://dx.doi.org/10.14429/dsj.66.8722

  1. Behavioral and plasma monoamine responses to high-speed railway noise stress in mice

    Directory of Open Access Journals (Sweden)

    Guoqing Di

    2013-01-01

    Full Text Available Studies have reported that railway noise causes stress responses. To evaluate the effects of high-speed railway (HSR noise on behaviors and plasma monoamines. Institute of cancer research mice were exposed to previously recorded HSR noise for 53 days. The noise was arranged according to the HSR′s 24-h traffic number and adjusted to a day-night equivalent continuous A-weighted sound pressure level (Ldn of 70 dB (A. The open field test (OFT and the light/dark box test were applied to observe mice behaviors. High performance liquid chromatography-fluorimetric detection was performed to determine the concentrations of plasma norepinephrine (NE, dopamine (DA, serotonin (5-hydroxytryptamine, 5-HT. Data were analyzed by two-way analysis of variance using SPSS 16.0. After 53 days of noise exposure, center time and the frequency of line crossing of the exposed mice decreased significantly in the OFT compared with the control group. Meanwhile, transitions and the time spent in the lit compartment of the exposed group decreased significantly in the light/dark box test. After 40 days of HSR noise exposure, the concentrations of plasma DA of the exposed group were significantly higher than those of the control group, while the plasma NE and 5-HT concentrations showed no significant difference between the two groups. The behavioral tests indicate that 70 dB (A HSR noise can result in anxiety-like behaviors in mice. The physiological results show that plasma DA is more sensitive to HSR noise compared with NE and 5-HT.

  2. Measured and calculated noise reduction of rail dampers and absorption plates on a high speed slab track

    NARCIS (Netherlands)

    Dittrich, M.G.; Graafland, F.; Eisses, A.R.; Nijhof, M.J.J.

    2015-01-01

    Rail dampers and sound absorbing plates have been tested on a high speed railway slab track in a walled cutting at a noise sensitive location. Their noise reduction has been determined from pass-by measurements during service and predicted using BEM calculations. The cutting depth, noise barrier hei

  3. A DFB Fiber Laser Sensor System with Ultra-High Resolution and Its Noise Analysis

    Institute of Scientific and Technical Information of China (English)

    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.

  4. Single phase bi-directional AC-DC converter with reduced passive components size and common mode electro-magnetic interference

    Energy Technology Data Exchange (ETDEWEB)

    Mi, Chris; Li, Siqi

    2017-01-31

    A bidirectional AC-DC converter is presented with reduced passive component size and common mode electro-magnetic interference. The converter includes an improved input stage formed by two coupled differential inductors, two coupled common and differential inductors, one differential capacitor and two common mode capacitors. With this input structure, the volume, weight and cost of the input stage can be reduced greatly. Additionally, the input current ripple and common mode electro-magnetic interference can be greatly attenuated, so lower switching frequency can be adopted to achieve higher efficiency.

  5. Dynamical response of the Galileo Galilei on the ground rotor to test the equivalence principle: Theory, simulation, and experiment. II. The rejection of common mode forces

    Science.gov (United States)

    Comandi, G. L.; Toncelli, R.; Chiofalo, M. L.; Bramanti, D.; Nobili, A. M.

    2006-03-01

    "Galileo Galilei on the ground" (GGG) is a fast rotating differential accelerometer designed to test the equivalence principle (EP). Its sensitivity to differential effects, such as the effect of an EP violation, depends crucially on the capability of the accelerometer to reject all effects acting in common mode. By applying the theoretical and simulation methods reported in Part I of this work, and tested therein against experimental data, we predict the occurrence of an enhanced common mode rejection of the GGG accelerometer. We demonstrate that the best rejection of common mode disturbances can be tuned in a controlled way by varying the spin frequency of the GGG rotor.

  6. Background Noise Distribution before and afterHigh-Resolution Processing in Ship-borne Radar

    Institute of Scientific and Technical Information of China (English)

    ZHANGZhong

    2005-01-01

    When high-resolution algorithm is applied in ship-borne radar~ high-resolution algorithm's nonlinearity and distributional characteristics before highresolution processing determine background clutter's distributional characteristics after high-resolution and detector design afterwards. Because background noise before high-resolution has physical significance, the statistical model of first-order Bragg lines and second order components of sea clutter is put forward. Then by using higher-order cumulative quantity's statistical verification of actually measured data, it is concluded that background noise before high-resolution conforms to normal distribution in ship-borne radar. The non-linearity of high-resolution algorithm determines that background noise after high-resolution processing conforms to non-normal distribution. Non-normal distributed clutter mainly include Weibull, Lognormal and K clutter. Rayleigh clutter can be seen as special case of Weibull clutter. These clutter have differently statistical characteristics and can be discriminated by clutter characteristics recognition. The numerical domain's distribution after high-resolution processing is determined by improved minimum entropy clutter characteristics recognition method based on rule AIC, namely two-parameter domain scanning method. This identification method has higher recognition rate. It is verified that background noise after high-resolution by pre-whitenedMUSIC conforms to lognormal distribution.

  7. Shot-noise-limited optical Faraday polarimetry with enhanced laser noise cancelling

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiaming [School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States); Luo, Le, E-mail: leluo@iupui.edu; Carvell, Jeff; Cheng, Ruihua [Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States); Lai, Tianshu, E-mail: stslts@mail.sysu.edu.cn; Wang, Zixin, E-mail: wangzix@mail.sysu.edu.cn [School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2014-03-14

    We present a shot-noise-limited measurement of optical Faraday rotations with sub-ten-nanoradian angular sensitivity. This extremely high sensitivity is achieved by using electronic laser noise cancelling and phase sensitive detection. Specially, an electronic laser noise canceller with a common mode rejection ratio of over 100 dB was designed and built for enhanced laser noise cancelling. By measuring the Faraday rotation of ambient air, we demonstrate an angular sensitivity of up to 9.0×10{sup −9} rad/√(Hz), which is limited only by the shot-noise of the photocurrent of the detector. To date, this is the highest angular sensitivity ever reported for Faraday polarimeters in the absence of cavity enhancement. The measured Verdet constant of ambient air, 1.93(3)×10{sup −9}rad/(G cm) at 633 nm wavelength, agrees extremely well with the earlier experiments using high finesse optical cavities. Further, we demonstrate the applications of this sensitive technique in materials science by measuring the Faraday effect of an ultrathin iron film.

  8. High Dynamic Range RF Front End with Noise Cancellation and Linearization for WiMAX Receivers

    Directory of Open Access Journals (Sweden)

    J.-M. Wu

    2012-06-01

    Full Text Available This research deals with verification of the high dynamic range for a heterodyne radio frequency (RF front end. A 2.6 GHz RF front end is designed and implemented in a hybrid microwave integrated circuit (HMIC for worldwide interoperability for microwave access (WiMAX receivers. The heterodyne RF front end consists of a low-noise amplifier (LNA with noise cancellation, an RF bandpass filter (BPF, a downconverter with linearization, and an intermediate frequency (IF BPF. A noise canceling technique used in the low-noise amplifier eliminates a thermal noise and then reduces the noise figure (NF of the RF front end by 0.9 dB. Use of a downconverter with diode linearizer also compensates for gain compression, which increases the input-referred third-order intercept point (IIP3 of the RF front end by 4.3 dB. The proposed method substantially increases the spurious-free dynamic range (DRf of the RF front end by 3.5 dB.

  9. Measurement of high-power microwave pulse under intense electromagnetic noise

    Indian Academy of Sciences (India)

    Amitava Roy; S K Singh; R Menon; D Senthil Kumar; R Venkateswaran; M R Kulkarni; P C Saroj; K V Nagesh; K C Mittal; D P Chakravarthy

    2010-01-01

    KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator (VIRCATOR) device. HPM power measurements were carried out using a transmitting–receiving system in the presence of intense high frequency (a few MHz) electromagnetic noise. Initially, the diode detector output signal could not be recorded due to the high noise level persisting in the ambiance. It was found that the HPM pulse can be successfully detected using wide band antenna, RF cable and diode detector set-up in the presence of significant electromagnetic noise. Estimated microwave peak power was ∼ 59.8 dBm (∼ 1 kW) at 7 m distance from the VIRCATOR window. Peak amplitude of the HPM signal varies on shot-to-shot basis. Duration of the HPM pulse (FWHM) also varies from 52 ns to 94 ns for different shots.

  10. An ultra-low noise, high-voltage piezo-driver.

    Science.gov (United States)

    Pisenti, N C; Restelli, A; Reschovsky, B J; Barker, D S; Campbell, G K

    2016-12-01

    We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250 V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total root-mean-square noise of ≈100 μV (1 Hz-100 kHz). A low-voltage (±10 V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150 mA at ±15 V.

  11. An ultra-low noise, high-voltage piezo-driver

    Science.gov (United States)

    Pisenti, N. C.; Restelli, A.; Reschovsky, B. J.; Barker, D. S.; Campbell, G. K.

    2016-12-01

    We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250 V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total root-mean-square noise of ≈100 μV (1 Hz-100 kHz). A low-voltage (±10 V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150 mA at ±15 V.

  12. Automotive Interior Noise Reduction in High Frequency Using Statistical Energy Analysis

    Institute of Scientific and Technical Information of China (English)

    CHEN Xin; WANG Deng-feng; ZHU Lei; MA Zheng-dong

    2009-01-01

    Statistical energy analysis (SEA) is an effective method for predicting high frequency vibro-acoustic performance of automobiles. A full vehicle SEA model is presented for interior noise reduction. It is composed of a number of subsystems based on a 3D model with all parameters for each subsystem. The excitation inputs are measured through road tests in different conditions, including inputs from the engine vibration and the sound pressure of the engine bay. The accuracy in high frequency of SEA model is validated, by comparing the analysis results with the testing pressure level data at driver's right ear. Noise contribution and sensitivity of key subsystems are analyzed. Finally, the effectiveness of noise reduction is verified. Based on the SEA model, an approach combining test and simulation is proposed for the noise vibration and harshness (NVH) design in vehicle development. It contains building the SEA model, testing for subsystem parameter identification, validating the simulation model, identifying subsystem power inputs, analyzing the design sensitivity. An example is given to demonstrate the interior noise reduction in high frequency.

  13. Corona noise model of high-voltage AC transmission lines and engineering applications

    Institute of Scientific and Technical Information of China (English)

    Wu Jiuhui; Di Zelong

    2013-01-01

    In order to predict the levels of corona noise from high-voltage alternating current (AC) transmission lines,the mechanism of corona noise and the corresponding theoretical prediction model are investigated.On the basis of Drude model,the motion of positive and negative ions produced by high-voltage corona is analyzed,and the mechanism of corona noise is discovered.The theoretical prediction model is put forward by using Kirchhoff formula,which is verified by the well agreement between our result and others',considering the case of three-phase single lines.Moreover,the calculation results show that for both single and bundled lines,the sound pressure level of the typical frequency,i.e.twice the power frequency,attenuates slowly and leads to an obviously interferential phenomenon near the transmission lines,but the level of the bundled lines is smaller than that of the single ones under the same transmission voltage.Based on the mechanism of corona noise and the prediction model,it is obvious that bundled lines and/or increased line radius can be adopted to reduce corona noise in the practical engineering applications effectively.This model can also provide a theoretical guidance for the high-volt-age AC transmission line design.

  14. Phase noise measurement of high-power fiber amplifiers

    Institute of Scientific and Technical Information of China (English)

    Hu Xiao; Xiaolin Wang; Yanxing Ma; Bing He; Pu Zhou; Jun Zhou; Xiaojun Xu

    2011-01-01

    We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique. Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an amplifier, whereas the high frequency components related to laser power affect the control bandwidth. The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9 kHz under the output power of 25,55, 125, and 180W, respectively. The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.%@@ We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique.Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an am-plifier, whereas the high frequency components related to laser power affect the control bandwidth.The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9kHz under the output power of 25, 55, 125, and 180 W, respectively.The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.

  15. High-frequency hearing thresholds: effects of age, occupational ultrasound and noise exposure.

    Science.gov (United States)

    Maccà, Isabella; Scapellato, Maria Luisa; Carrieri, Mariella; Maso, Stefano; Trevisan, Andrea; Bartolucci, Giovanni Battista

    2015-02-01

    It has been suggested that high-frequency audiometry (HFA) could represent a useful preventive measure in exposed workers. The aim was to investigate the effects of age, ultrasound and noise on high-frequency hearing thresholds. We tested 24 industrial ultrasound-exposed subjects, 113 industrial noise-exposed subjects and 148 non-exposed subjects. Each subject was tested with both conventional-frequency (0.125-8 kHz) and high-frequency (9-18 kHz) audiometry. The hearing threshold at high frequency deteriorated as a function of age, especially in subjects more than 30 years old. The ultrasound-exposed subjects had significantly higher hearing thresholds than the non-exposed ones at the high frequencies, being greatest from 10 to 14 kHz. This hearing loss was already significantly evident in subjects with exposure frequencies 4 and 6 kHz and at the high frequency of 14 kHz. After stratification for age, there was a significant difference between the two groups at 9-10 and 14-15 kHz only for those under 30 years of age. Multivariate analysis indicated that age was the primary predictor, and noise and ultrasound exposure the secondary predictors of hearing thresholds in the high-frequency range. The results suggest that HFA could be useful in the early diagnosis of noise-induced hearing loss in younger groups of workers (under 30 years of age).

  16. Required changes in emission standards for high-frequency noise in power systems

    Energy Technology Data Exchange (ETDEWEB)

    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)

  17. Low-frequency suppression of random-telegraph-noise spectra in high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ashkenazy, V.D. (Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)); Jung, G. (Department of Physics, Ben Gurion University of the Negev, 84105 Beer-Sheva (Israel) Instytut Fizuki, Polish Academy of Sciences, 02668 Warszawa (Poland)); Khalfin, I.B. (Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)); Shapiro, B.Y. (Jack and Pearl Resnik Institute of Advanced Technology, Bar-Ilan University, 52100, Ramat Gan (Israel) Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel))

    1995-01-01

    Interaction of the random-telegraph-noise signals with pinned Abrikosov vortices in granular high-temperature superconductors is investigated. It is shown that the low-frequency part of random-noise spectra is suppressed due to interaction of Abrikosov vortices with pinning centers at low magnetic fields and/or due to mutual interactions of vortices in an Abrikosov lattice at high magnetic fields. Values of characteristic frequencies below which spectra are suppressed are evaluated for various experimental configurations including a typical experimental thin-film strip geometry. It is shown that characteristic frequencies and the functional dependence of the low-frequency part of the noise spectra strongly depend on the external magnetic field.

  18. High-power and low-intensity noise laser at 1064  nm.

    Science.gov (United States)

    Guiraud, Germain; Traynor, Nicholas; Santarelli, Giorgio

    2016-09-01

    We have developed a single-frequency, narrow-linewidth (Δνlaser operating at 1064 nm with a high output power (50 W). The laser is based on an ytterbium-doped fiber master oscillator power amplifier architecture with an output beam at the diffraction limit. An output power of 50 W is obtained with two amplification stages using a 50 mW diode laser seeder. We have carefully studied the relative intensity noise at each amplification stage. The detrimental effect due to stimulated Brillouin scattering on residual amplitude noise has been observed on the high-power booster stage. After careful optimization, this laser exhibits low intensity noise with a RMS value equal to 0.012% (1 kHz/10 MHz) at 50 W.

  19. Intelligibility of speech in noise at high presentation levels: effects of hearing loss and frequency region.

    Science.gov (United States)

    Summers, Van; Cord, Mary T

    2007-08-01

    These experiments examined how high presentation levels influence speech recognition for high- and low-frequency stimuli in noise. Normally hearing (NH) and hearing-impaired (HI) listeners were tested. In Experiment 1, high- and low-frequency bandwidths yielding 70%-correct word recognition in quiet were determined at levels associated with broadband speech at 75 dB SPL. In Experiment 2, broadband and band-limited sentences (based on passbands measured in Experiment 1) were presented at this level in speech-shaped noise filtered to the same frequency bandwidths as targets. Noise levels were adjusted to produce approximately 30%-correct word recognition. Frequency bandwidths and signal-to-noise ratios supporting criterion performance in Experiment 2 were tested at 75, 87.5, and 100 dB SPL in Experiment 3. Performance tended to decrease as levels increased. For NH listeners, this "rollover" effect was greater for high-frequency and broadband materials than for low-frequency stimuli. For HI listeners, the 75- to 87.5-dB increase improved signal audibility for high-frequency stimuli and rollover was not observed. However, the 87.5- to 100-dB increase produced qualitatively similar results for both groups: scores decreased most for high-frequency stimuli and least for low-frequency materials. Predictions of speech intelligibility by quantitative methods such as the Speech Intelligibility Index may be improved if rollover effects are modeled as frequency dependent.

  20. High pressure air jet in the endoscopic preparation room: risk of noise exposure on occupational health.

    Science.gov (United States)

    Chiu, King-Wah; Lu, Lung-Sheng; Wu, Cheng-Kun

    2015-01-01

    After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment was taken during 7 automatic endoscopic reprocessors (AERs) and combined with/without HPAJ use over an 8-hour time-weighted average (TWA). Analytical procedures of the NIOSH and the ISO for noise-induced hearing loss were estimated to develop analytic models. The peak of the noise spectrum of combined HPAJ and 7 AERs was significantly higher than that of the 7 AERs alone (108.3 ± 1.36 versus 69.3 ± 3.93 dBA, P risk of hearing loss (HL > 2.5 dB) was 2.15% at 90 dBA, 11.6% at 95 dBA, and 51.3% at 100 dBA. The odds ratio was 49.1 (95% CI: 11.9 to 203.6). The noise generated by the HPAJ to work over TWA seriously affected the occupational health and safety of those working in an endoscopic preparation room.

  1. Effects of high-frequency emphasis and compression time constants on speech intelligibility in noise.

    Science.gov (United States)

    van Toor, Thijs; Verschuure, Hans

    2002-10-01

    The objectives of the study were to evaluate the effect of different settings with regard to speech intelligibility in noise both objectively and subjectively and thus determine a favoured setting of compression time parameters, pre-set program (high-frequency emphasis) or combination for each individual user in a prospective study. Another objective was to evaluate the relationship between patient characteristics (e.g. slope of hearing loss) and favoured settings. In total, 38 subjects divided over five audiological centres were fitted with the Philips Spaceline D71-40 BTE digital hearing aid. Subjects were asked to compare three predefined compression algorithms with different time constants, slow (indicated by the manufacturer as AVC), intermediate (NORMAL) and fast (SYLLABIC) over two 4-week periods using the intermediate setting in both comparisons and randomizing over the fast and slow conditions. A randomization determined whether a subject started with the comfort-oriented pre-set program (AUTO) or the speech intelligibility-oriented setting with high-frequency emphasis (SPIN). In a third 4-week period, the pre-sets AUTO and SPIN were compared using the setting of the compression time constants that gave the best results during the first two periods. Comparisons were made using a standard speech-in-noise test with three types of noise: continuous speaker noise, modulated ICRA-4 noise, and car noise. The patients were also asked to fill in a Dutch translation and adaptation of the APHAB questionnaire to indicate their impression of performance. The results indicate that no compression algorithm, pre-set or combination is favoured overall. The largest improvement in speech-in-noise scores was found with syllabic compression. The advantageous effect of high-frequency emphasis after optimization of compression timing is small. The APHAB showed that users tend to prefer the SPIN setting. We found no relationship between favoured compression or pre-set and the

  2. Design of low noise airfoil with high aerodynamic performance for use on small wind turbines

    Institute of Scientific and Technical Information of China (English)

    Taehyung; KIM; Seungmin; LEE; Hogeon; KIM; Soogab; LEE

    2010-01-01

    Wind power is one of the most reliable renewable energy sources and internationally installed capacity is increasing radically every year.Although wind power has been favored by the public in general,the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased.Low noise wind turbine design is becoming more and more important as noise is spreading more adverse effect of wind turbine to public.This paper demonstrates the design of 10 kW class wind turbines,each of three blades,a rotor diameter 6.4 m,a rated rotating speed 200 r/min and a rated wind speed 10 m/s.The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade is trailing edge noise from the outer 25% of the blade.Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at 1.02×106 with a lift performance,which is resistant to surface contamination and turbulence intensity.The objectives in the design process are to reduce noise emission,while sustaining high aerodynamic efficiency.Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al.and Lowson associated with typical wind turbine operation conditions.During the airfoil redesign process,the aerodynamic performance is analyzed to reduce the wind turbine power loss.The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis.Therefore,the new optimized airfoil showing 2.9 dB reductions of total sound pressure level(SPL) and higher aerodynamic performance are achieved.

  3. Designing high-impedance/low-noise superinductances for quantum electronics

    Science.gov (United States)

    Pop, Ioan; Minev, Zlatko; Masluk, Nicholas; Kamal, Archana; Devoret, Michel

    2012-02-01

    Superinductances are essential circuit elements which enable the suppression of charge fluctuations in superconducting fluxonium qubits [1] and in other Josephson junction devices [2]. Commonly implemented as an array of Josephson junctions, superinductances have two main limitations. Firstly, the spurious capacitive coupling of the chain islands to ground lowers the plasma frequency of the chain, and consequently limits the operational bandwidth. Secondly, coherent quantum phase-slips (CQPS) [3] in the Josephson junction chain induce time dependent inductance fluctuations via the Aharonov-Casher effect [4]. We present the application of a novel lithographic technique [5] which enables the fabrication of arrays with optimal junction-capacitance to ground-capacitance ratio. We also present new superinductance designs which topologically suppress the CQPS, allowing the implementation of practically phase-slip free high inductance Josephson junction.[4pt] [1] Manucharyan et al., Science, 326 (2009)[0pt] [2] Guichard and Hekking, PRB, 81 (2010)[0pt] [3] Matveev et al. PRL, 89 (2002)[0pt] [4] Pop et al., arXiv:1105.6204 and Manucharyan et al., arXiv:1012.1928[0pt] [5] Lecocq et al., Nanotechnology, 22 (2011)

  4. High-Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement

    Science.gov (United States)

    Quackenbush, Todd R.; McKillip, Robert M., Jr.

    2011-01-01

    One of key NASA goals is to develop and integrate noise reduction technology to enable unrestricted air transportation service to all communities. One of the technical priorities of this activity has been to account for and reduce noise via propulsion/airframe interactions, identifying advanced concepts to be integrated with the airframe to mitigate these noise-producing mechanisms. An adaptive geometry chevron using embedded smart structures technology offers the possibility of maximizing engine performance while retaining and possibly enhancing the favorable noise characteristics of current designs. New high-temperature shape memory alloy (HTSMA) materials technology enables the devices to operate in both low-temperature (fan) and high-temperature (core) exhaust flows. Chevron-equipped engines have demonstrated reduced noise in testing and operational use. It is desirable to have the noise benefits of chevrons in takeoff/landing conditions, but have them deployed into a minimum drag position for cruise flight. The central feature of the innovation was building on rapidly maturing HTSMA technology to implement a next-generation aircraft noise mitigation system centered on adaptive chevron flow control surfaces. In general, SMA-actuated devices have the potential to enhance the demonstrated noise reduction effectiveness of chevron systems while eliminating the associated performance penalty. The use of structurally integrated smart devices will minimize the mechanical and subsystem complexity of this implementation. The central innovations of the effort entail the modification of prior chevron designs to include a small cut that relaxes structural stiffness without compromising the desired flow characteristics over the surface; the reorientation of SMA actuation devices to apply forces to deflect the chevron tip, exploiting this relaxed stiffness; and the use of high-temperature SMA (HTSMA) materials to enable operation in the demanding core chevron environment

  5. Turbulent Flow Physics and Noise in High Reynolds Number Compressible Jets

    Science.gov (United States)

    Glauser, Mark

    2016-11-01

    In this talk I will present a snapshot of our ongoing research in high Reynolds number turbulent compressible jets. The high speed axisymmetric jet work (Mach 0.6 - 1.1) has been jointly performed with Spectral Energies LLC through AFRL support and involves 10 kHz and large window PIV data extracted from the near field jet plume, simultaneously sampled with near field pressure and far field noise. We have learned from the simultaneously sampled 10 kHz PIV near field plume and far field noise data, using POD/OID and Wavelet filtering, that there are certain "loud" velocity modes that have low averaged turbulent kinetic energy content but strongly correlate with the far field noise. From the large window PIV data obtained at Mach 1.0 and 1.1, specific POD modes were found to contain important physics of the problem. For example, the large-scale structure of the jet, shock-related fluctuations, and turbulent mixing regions of the flow were isolated through POD. By computing cross correlations, particular POD modes were found to be related to particular noise spectra. I will conclude with a description of our complex nozzle work which uses the multi-stream supersonic single expansion rectangular nozzle (SERN) recently installed in our large anechoic chamber at SU. This work is funded from both AFOSR (joint with OSU with a primary focus on flow physics) and Spectral Energies LLC (via AFRL funds with a focus on noise). Particular emphasis will be on insight gained into this complex 3D flow field (and its relationship to the far field noise) from applications of POD, Wavelet filtering and DMD to various numerical (LES) and experimental (PIV, high speed schlieren, near and far field pressure) data sets, at a core nozzle Mach number of 1.6 and a second stream Mach number of 1.0.

  6. The Capacity of Finite-State Channels in the High-Noise Regime

    CERN Document Server

    Pfister, Henry D

    2010-01-01

    This paper considers the derivative of the entropy rate of a hidden Markov process with respect to the observation probabilities. The main result is a compact formula for the derivative that can be evaluated easily using Monte Carlo methods. It is applied to the problem of computing the capacity of a finite-state channel (FSC) and, in the high-noise regime, the formula has a simple closed-form expression that enables series expansion of the capacity of a FSC. This expansion is evaluated for a binary-symmetric channel under a (0,1) run-length limited constraint and an intersymbol-interference channel with Gaussian noise.

  7. High levels of sound pressure: acoustic reflex thresholds and auditory complaints of workers with noise exposure

    Directory of Open Access Journals (Sweden)

    Alexandre Scalli Mathias Duarte

    2015-08-01

    Full Text Available INTRODUCTION: The clinical evaluation of subjects with occupational noise exposure has been difficult due to the discrepancy between auditory complaints and auditory test results. This study aimed to evaluate the contralateral acoustic reflex thresholds of workers exposed to high levels of noise, and to compare these results to the subjects' auditory complaints.METHODS: This clinical retrospective study evaluated 364 workers between 1998 and 2005; their contralateral acoustic reflexes were compared to auditory complaints, age, and noise exposure time by chi-squared, Fisher's, and Spearman's tests.RESULTS: The workers' age ranged from 18 to 50 years (mean = 39.6, and noise exposure time from one to 38 years (mean = 17.3. We found that 15.1% (55 of the workers had bilateral hearing loss, 38.5% (140 had bilateral tinnitus, 52.8% (192 had abnormal sensitivity to loud sounds, and 47.2% (172 had speech recognition impairment. The variables hearing loss, speech recognition impairment, tinnitus, age group, and noise exposure time did not show relationship with acoustic reflex thresholds; however, all complaints demonstrated a statistically significant relationship with Metz recruitment at 3000 and 4000 Hz bilaterally.CONCLUSION: There was no significance relationship between auditory complaints and acoustic reflexes.

  8. High Degree Cubature Federated Filter for Multisensor Information Fusion with Correlated Noises

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2016-01-01

    Full Text Available This paper proposes an improved high degree cubature federated filter for the nonlinear fusion system with cross-correlation between process and measurement noises at the same time using the fifth-degree cubature rule and the decorrelated principle in its local filters. The master filter of the federated filter adopts the no-reset mode to fuse local estimates of local filters to generate a global estimate according to the scalar weighted rule. The air-traffic maneuvering target tracking simulations are performed between the proposed filter and the fifth-degree cubature federated filter. Simulations results demonstrate that the proposed filter not only can achieve almost the same accuracy as the fifth-degree cubature federated filter with independent white noises, but also has superior performance to the fifth-degree cubature federated filter while the noises are cross-correlated at the same time.

  9. An integrated low 1/f noise and high-sensitivity CMOS instrumentation amplifier for TMR sensors

    Science.gov (United States)

    Gao, Zhiqiang; Luan, Bo; Zhao, Jincai; Liu, Xiaowei

    2017-03-01

    In this paper, a very low 1/f noise integrated Wheatstone bridge magnetoresistive sensor ASIC based on magnetic tunnel junction (MTJ) technology is presented for high sensitivity measurements. The present CMOS instrumentation amplifier employs the gain-boost folded-cascode structure based on the capacitive-feedback chopper-stabilized technique. By chopping both the input and the output of the amplifier, combined with MTJ magnetoresistive sensitive elements, a noise equivalent magnetoresistance 1 nT/Hz1/2 at 2 Hz, the equivalent input noise spectral density 17 nV/Hz1/2(@2Hz) is achieved. The chip-scale package of the TMR sensor and the instrumentation amplifier is only about 5 mm × 5 mm × 1 mm, while the whole DC current dissipates only 2 mA.

  10. Low-frequency noise in high-{Tc} superconductor Josephson junctions, SQUIDs, and magnetometers

    Energy Technology Data Exchange (ETDEWEB)

    Miklich, A.H.

    1994-05-01

    Design and performance of high-T{sub c} dc superconducting quantum interference devices (SQUEDs), junctions that comprise them, and magnetometers made from them are described, with attention to sources of 1/f noise. Biepitaxial junctions are found to have large levels of critical current fluctuations which make them unsuitable for low-noise SQUIDS; this suggests a poorly connected interface at the grain boundary junction. SQUIDs from bicrystal junctions have levels of critical current noise controllable using bias current reversal techniques which leave the noise white down to frequencies of a few Hz. A SQUID with an energy resolution of 1.5{times}10{sup {minus}30} J Hz{sup {minus}1} at 1 Hz is reported. Magnetometers in which a (9 mm){sup 2} pickup loop is directly coupled to a SQUID body have achieved field resolutions of 93 fT Hz{sup {minus}1/2} down to frequencies below I Hz, improving to 39 fT Hz{sup {minus}1/2} at 1 Hz with the addition of a 50mm-diameter single-turn flux transformer. Poor coupling to pickup loop makes it difficult to satisfy competing goals of high field resolution and small detector size necessary for multichannel biomagnetic imaging. Improved coupling is demonstrated by the use of multiturn-input-coil flux transformers, and a resolution of 35 fT Hz{sup {minus}1/2} in the white noise region is reported with a (10 mm){sup 2} pickup loop. However, additional 1/f noise from processed multilayer structures in the transformer limits the resolution at 1 Hz to 114 fT Hz{sup {minus}1/2}. High-T{sub c} SQUIDs exhibit additional 1/f noise when cooled in a nonzero static magnetic field because of additional flux vortices trapped in the film, with the noise power at 1 Hz typically increasing by a factor of 10--20 in a field of 0.05mT (0.5 G). Finally, a SQUID-based voltmeter with a resolution of 9.2 pV.Hz{sup {minus}1/2} at 10 Hz (24 pV Hz{sup {minus}1/2} at 1 Hz) is described.

  11. Highly-efficient noise-assisted energy transport in classical oscillator systems

    CERN Document Server

    León-Montiel, R de J

    2013-01-01

    Photosynthesis is a biological process that involves the highly-efficient transport of energy captured from the sun to a reaction center, where conversion into useful biochemical energy takes place. Even though one can always use a quantum perspective to describe any physical process, since everything follows the laws of Quantum Mechanics, is the use of quantum theory imperative to explain this high efficiency? Several theoretical studies suggest that the high efficiency can only be understood as a result of the interplay between the quantum coherent evolution of the photosynthetic system, and noise introduced by its surrounding environment. Notwithstanding, we show here that noise-assisted highly-efficient energy transport can be found as well in purely classical systems; therefore, we might conclude that high efficiency energy transfer in photosynthetic systems could also be anticipated by classical models, without the need to resorting to quantum effects. Strikingly, the wider scope of applicability of the...

  12. Development of Low-Noise High Value Chromium Silicide Resistors for Cryogenic Detector Applications

    Science.gov (United States)

    Jhabvala, Murzy; Babu, Sachi; Monroy, Carlos; Darren, C.; Krebs, Carolyn A. (Technical Monitor)

    2001-01-01

    Extremely high sensitivity detectors, such as silicon bolometers are required in many NASA missions for detection of photons from the x-ray to the far infrared regions. Typically, these detectors are cooled to well below the liquid helium (LHe) temperature (4.2 K) to achieve the maximum detection performance. As photoconductors, they are generally operated with a load resistor and a pre-set bias voltage, which is then coupled to the input gate of a source-follower Field Effect Transistor (FET) circuit. It is imperative that the detector system signal to noise performance be limited by the noise of the detector and not by the noise of the external components. The load resistor value is selected to optimize the detector performance. These two criteria tend to be contradictory in that these detectors require load resistors in the hundreds of megaohms, which leads to a higher Johnson noise. Additionally, the physical size of the resistor must be small for device integration as required by such missions as the NASA High Resolution Airborne Wide-Band Camera (HAWC) instrument and the Submillimeter High Angular Resolution Camera (SHARC) for the Caltech Submillimeter Observatory (CSO). We have designed, fabricated and characterized thin film resistors using a CrSi/TiW/Al metal system on optical quality quartz substrates. The resistor values range from 100 megaohms to over 650 megaohms and are Johnson noise limited at LHe temperatures. The resistor film is sputtered with a sheet resistance ranging from 300 ohms to 1600 ohms and the processing sequence developed for these devices allows for chemically fine tuning the sheet resistance in-situ. The wafer fabrication process was of sufficiently high yield (>80%) providing clusters of good resistors for integrated multiple detector channels, a very important feature in the assembly of these two instruments.

  13. High temporal resolution mapping of seismic noise sources using heterogeneous supercomputers

    Science.gov (United States)

    Gokhberg, Alexey; Ermert, Laura; Paitz, Patrick; Fichtner, Andreas

    2017-04-01

    Time- and space-dependent distribution of seismic noise sources is becoming a key ingredient of modern real-time monitoring of various geo-systems. Significant interest in seismic noise source maps with high temporal resolution (days) is expected to come from a number of domains, including natural resources exploration, analysis of active earthquake fault zones and volcanoes, as well as geothermal and hydrocarbon reservoir monitoring. Currently, knowledge of noise sources is insufficient for high-resolution subsurface monitoring applications. Near-real-time seismic data, as well as advanced imaging methods to constrain seismic noise sources have recently become available. These methods are based on the massive cross-correlation of seismic noise records from all available seismic stations in the region of interest and are therefore very computationally intensive. Heterogeneous massively parallel supercomputing systems introduced in the recent years combine conventional multi-core CPU with GPU accelerators and provide an opportunity for manifold increase and computing performance. Therefore, these systems represent an efficient platform for implementation of a noise source mapping solution. We present the first results of an ongoing research project conducted in collaboration with the Swiss National Supercomputing Centre (CSCS). The project aims at building a service that provides seismic noise source maps for Central Europe with high temporal resolution (days to few weeks depending on frequency and data availability). The service is hosted on the CSCS computing infrastructure; all computationally intensive processing is performed on the massively parallel heterogeneous supercomputer "Piz Daint". The solution architecture is based on the Application-as-a-Service concept in order to provide the interested external researchers the regular access to the noise source maps. The solution architecture includes the following sub-systems: (1) data acquisition responsible for

  14. Correction of phase velocity bias caused by strong directional noise sources in high-frequency ambient noise tomography: a case study in Karamay, China

    Science.gov (United States)

    Wang, K.; Luo, Y.; Yang, Y.

    2016-12-01

    with results from geology surveys than those based on uncorrected ones. As ambient noise in high frequency band (>1Hz) is mostly related to human activities or climate events, both of which have strong directivity, the iterative approach demonstrated here helps improve the accuracy and resolution of ANT in imaging shallow earth structures.

  15. Correction of phase velocity bias caused by strong directional noise sources in high-frequency ambient noise tomography: a case study in Karamay, China

    Science.gov (United States)

    Wang, Kai; Luo, Yinhe; Yang, Yingjie

    2016-05-01

    corrected interstation dispersion measurements are more consistent with results from geology surveys than those based on uncorrected data. As ambient noise in high-frequency band (>1 Hz) is mostly related to human activities or climate events, both of which have strong directivity, the iterative approach demonstrated here helps improve the accuracy and resolution of ANT in imaging shallow earth structures.

  16. High finesse external cavity VCSELs: from very low noise lasers to dual frequency lasers

    Science.gov (United States)

    Baili, Ghaya; Alouini, Medhi; Morvan, Loic; Bretenaker, Fabien; Sagnes, Isabelle; Garnache, Arnaud; Dolfi, Daniel

    2011-01-01

    Low noise-level optical sources are required for numerous applications such as microwave photonics, fiber-optic sensing and time/frequency references distribution. In this paper, we demonstrate how inserting a SC active medium into a centimetric high-Q external cavity is a simple way to obtain a shot-noise-limited laser source over a very wide frequency bandwidth. This approach ensures, with a compact design, a sufficiently long photon lifetime to reach the oscillation-relaxation- free class-A regime. This concept has been illustrated by inserting a 1/2-VCSEL in an external cavity including an etalon filter. A -156dB/Hz relative intensity noise level is obtained over the 100 MHz to 18 GHz bandwidth of interest. This is several orders of magnitude better than the noise, previously observed in VCSELs, belonging to the class-B regime. The optimization, in terms of noise, is shown to be a trade-off between the cavity length and the laser mode filtering. The transition between the class-B and class-A dynamical behaviors is directly observed by continuously controlling the photon lifetime is a sub-millimetric to a centimetric cavity length. It's proven that the transition occurs progressively, without any discontinuity. Based on the same laser architecture, tunable dual-frequency oscillation is demonstrated by reducing the polarized eigenstates overlap in the gain medium. The class-A dynamics of such a laser, free of relaxation oscillations, enables to suppress the electrical phase noise in excess, usually observed in the vicinity of the beat note. An original technique for jitter reduction in mode-locked VECSELs is also investigated. Such lasers are needed for photonic analog to digital converters.

  17. High-frequency audiometry: a means for early diagnosis of noise-induced hearing loss.

    Science.gov (United States)

    Mehrparvar, Amir H; Mirmohammadi, Seyyed J; Ghoreyshi, Abbas; Mollasadeghi, Abolfazl; Loukzadeh, Ziba

    2011-01-01

    Noise-induced hearing loss (NIHL), an irreversible disorder, is a common problem in industrial settings. Early diagnosis of NIHL can help prevent the progression of hearing loss, especially in speech frequencies. For early diagnosis of NIHL, audiometry is performed routinely in conventional frequencies. We designed this study to compare the effect of noise on high-frequency audiometry (HFA) and conventional audiometry. In a historical cohort study, we compared hearing threshold and prevalence of hearing loss in conventional and high frequencies of audiometry among textile workers divided into two groups: With and without exposure to noise more than 85 dB. The highest hearing threshold was observed at 4000 Hz, 6000 Hz and 16000 Hz in conventional right ear audiometry, conventional left ear audiometry and HFA in each ear, respectively. The hearing threshold was significantly higher at 16000 Hz compared to 4000. Hearing loss was more common in HFA than conventional audiometry. HFA is more sensitive to detect NIHL than conventional audiometry. It can be useful for early diagnosis of hearing sensitivity to noise, and thus preventing hearing loss in lower frequencies especially speech frequencies.

  18. High Resolution DOA Estimation Using Unwrapped Phase Information of MUSIC-Based Noise Subspace

    Science.gov (United States)

    Ichige, Koichi; Saito, Kazuhiko; Arai, Hiroyuki

    This paper presents a high resolution Direction-Of-Arrival (DOA) estimation method using unwrapped phase information of MUSIC-based noise subspace. Superresolution DOA estimation methods such as MUSIC, Root-MUSIC and ESPRIT methods are paid great attention because of their brilliant properties in estimating DOAs of incident signals. Those methods achieve high accuracy in estimating DOAs in a good propagation environment, but would fail to estimate DOAs in severe environments like low Signal-to-Noise Ratio (SNR), small number of snapshots, or when incident waves are coming from close angles. In MUSIC method, its spectrum is calculated based on the absolute value of the inner product between array response and noise eigenvectors, means that MUSIC employs only the amplitude characteristics and does not use any phase characteristics. Recalling that phase characteristics plays an important role in signal and image processing, we expect that DOA estimation accuracy could be further improved using phase information in addition to MUSIC spectrum. This paper develops a procedure to obtain an accurate spectrum for DOA estimation using unwrapped and differentiated phase information of MUSIC-based noise subspace. Performance of the proposed method is evaluated through computer simulation in comparison with some conventional estimation methods.

  19. Application of sound intensity and partial coherence to identify interior noise sources on the high speed train

    Science.gov (United States)

    Fan, Rongping; Su, Zhongqing; Meng, Guang; He, Caichun

    2014-06-01

    In order to provide a quieter riding environment for passengers, sound quality refinement of rail vehicle is a hot issue. Identification of interior noise sources is the prerequisite condition to reduce the interior noise on high speed train. By considering contribution of noise sources such as rolling noise, mechanical equipment noise, structure-borne noise radiated by car body vibration to the interior noise, the synthesized measurement of sound intensity, sound pressure levels and vibration have been carried out in four different carriages on high speed train. The sound intensity and partial coherence methods have been used to identify the most significant interior noise sources. The statistical analysis results of sound intensity near window and floor on four carriages indicate that sound intensity near floor is higher than that near window at three traveling speeds. Ordinary and partial coherent analysis of vibro-acoustical signals show that the major internal noise source is structural-borne sound radiated by floor vibration. These findings can be utilized to facilitate the reduction of interior noise in the future.

  20. 高速列车透射噪声与结构噪声的分离%High speed train transmission noise and structural noise separation

    Institute of Scientific and Technical Information of China (English)

    纳跃跃; 谢翀

    2013-01-01

    高速列车噪声是影响车内旅客舒适度和铁路沿线居民生活质量的重要因素,如何有效的降低噪声是高速列车设计者们所关心的问题之一.研究表明,高速列车的车内噪声由透射噪声与结构噪声组成,如何有效的从车内噪声中分离出这两种噪声成分将为列车的减振降噪设计提供一定的指导作用.本文以高速列车实车噪声数据为研究对象,首先运用多种数字信号处理的方法对高速列车噪声数据进行了分析,总结了高速列车噪声的主要特点;然后通过对列车静止时和运行时的噪声透射情形分别进行建模和分析,指出可以利用车体的频响特性作为反映车体隔声性能的声学参数,并提出了一种计算频响特性的简便算法;最后,利用该算法从实车噪声数据中计算出了车体的频响特性,并在此基础上实现了透射噪声与结构噪声的分离.%High speed train noise level is an important factor with respect to passenger comfort and life quality of residents along the railway.How to attenuate the noise level is an important research direction that train designers care about.Studies show that train interior noise is consist of transmission noise and structural noise.Separating these two kinds of components from their overall observations will provide further guide to high speed train noise reduction design.The research is based on the real-world high speed train noise data.First,data are analyzed by different digital signal processing methods and some basic properties of the train noise signal are concluded.Then,by modeling and analyzing the noise transmission circumstances when train is stationary and moving,train body frequency response is used to measure the noise insulation quality,and an algorithm is proposed to calculate the frequency response conveniently.At last,train body frequency response is calculated according to the real-world train noise data via the proposed algorithm

  1. High critical temperature superconducting quantum interference device magnetometer with feedforward active noise control system for magnetocardiographic measurement in unshielded circumstances

    Energy Technology Data Exchange (ETDEWEB)

    Mizukami, A.; Nishiura, H.; Sakuta, K.; Kobayashi, T

    2003-10-15

    Magnetocardiographic (MCG) measurement in unshielded environment for practical use requires to suppress the environmental magnetic noise. We have designed the high critical temperature superconducting quantum interference device (High-T{sub c} SQUID) magnetometer with feedforward active noise control (ANC) system to suppress the environmental magnetic noise. The compensatory system consisted of two SQUID magnetometers, a digital signal processor (DSP) and the coil wound around the input magnetometer. The DSP calculated the output data to minimize the environmental noise from the input and reference date and then the coil generated the magnetic field to cancel the environmental noise. This method achieved the effective noise attenuation below 100 Hz about 40 dB. MCG measurement in unshielded environment was also performed.

  2. Effect of high energy electron irradiation on low frequency noise in 4H-SiC Schottky diodes

    Science.gov (United States)

    Kozlovski, V. V.; Lebedev, A. A.; Levinshtein, M. E.; Rumyantsev, S. L.; Palmour, J. W.

    2017-03-01

    The low-frequency noise in high voltage Ni/4H-SiC Schottky diodes irradiated with high energy (0.9 MeV) electrons was studied in the frequency range from 1 Hz to 50 kHz, temperature interval 295-410 K, and irradiation dose Φ from 0.2 × 1016 cm-2 to 7 × 1016 cm-2. The noise amplitude was found monotonically increasing with the irradiation dose. With the irradiation dose increase, the noise spectra on the linear part of the current voltage characteristic transform from the 1/f noise to the generation recombination noise of at least two trap levels. One of these levels can be classified as Z1/2 with the capture cross section determined from the noise measurements to be ˜10-15 cm2.

  3. Highly Efficient Noise-Assisted Energy Transport in Classical Oscillator Systems

    Science.gov (United States)

    León-Montiel, R. de J.; Torres, Juan P.

    2013-05-01

    Photosynthesis is a biological process that involves the highly efficient transport of energy captured from the Sun to a reaction center, where conversion into useful biochemical energy takes place. Using a quantum description, Rebentrost et al. [New J. Phys. 11, 033003 (2009)] and Plenio and Huelga [New J. Phys. 10, 113019 (2008)] have explained this high efficiency as the result of the interplay between the quantum coherent evolution of the photosynthetic system and noise introduced by its surrounding environment. Even though one can always use a quantum perspective to describe any physical process, since everything follows the laws of quantum mechanics, is the use of quantum theory imperative to explain this high efficiency? Recently, it has been shown by Eisfeld and Briggs [Phys. Rev. E 85, 046118 (2012)] that a purely classical model can be used to explain main aspects of the energy transfer in photosynthetic systems. Using this approach, we demonstrate explicitly here that highly efficient noise-assisted energy transport can be found as well in purely classical systems. The wider scope of applicability of the enhancement of energy transfer assisted by noise might open new ways for developing new technologies aimed at enhancing the efficiency of a myriad of energy transfer systems, from information channels in microelectronic circuits to long-distance high-voltage electrical lines.

  4. The high speed low noise multi-data processing signal process circuit research of remote sensing

    Science.gov (United States)

    Su, Lei; Jiang, Haibin; Dong, Wang

    2013-08-01

    The high speed, low noise and integration characteristic are the main technology and the main development directions on the signal process circuit of the image sensor, especially in high resolution remote sensing. With these developments, the high noise limiting circuits, high speed data transfer system and the integrated design of the signal process circuit become more and more important. Therefore the requirement of the circuit system simulation is more and more important during the system design and PCB board design process. A CCD signal process circuit system which has the high speed, low noise and several selectable operate modes function was designed and certificated in this paper, during the CCD signal process circuit system design, simulation was made which include the signal integrity and the power integrity. The important devices such as FPGA and the DDR2 device were simulated, using the power integrity simulation the sensitive power planes of the FPGA on the PCB was modified to make the circuit operate more stabilize on a higher frequency. The main clock path and the high speed data path of the PCB board were simulated with the signal integrity. All the simulation works make the signal process circuit system's image's SNR value get higher and make the circuit system could operate well on higher frequency. In the board testing process, the PCB time diagrams were listed on the testing chapter and the wave's parameter meets the request. The real time diagram and the simulated result of the PCB board was listed respectively. The CCD signal process circuit system's images' SNR (Signal Noise Ratio) value, the 14bit AFE slew rate and the data transfer frequency is listed in the paper respective.

  5. Development of a high-fidelity noise prediction and propagation model for noise generated from wind turbines

    DEFF Research Database (Denmark)

    Debertshäuser, Harald; Shen, Wen Zhong; Zhu, Wei Jun

    2015-01-01

    technique for any kind of flow conditions. We investigated laminar/ turbulent inflow, as well as wind shear and yaw of the 2.3 MW NM80 wind turbine. The turbulent case shows higher noise levels than the laminar one. Yaw changes the directivity from a dipole characteristic to an oval shape, inclined...

  6. Low Complexity DFT-Domain Noise PSD Tracking Using High-Resolution Periodograms

    NARCIS (Netherlands)

    Heusdens, R.; Hendriks, R.C.; Jensen, J.; Kjems, U.

    2009-01-01

    Although most noise reduction algorithms are critically dependent on the noise power spectral density (PSD), most procedures for noise PSD estimation fail to obtain good estimates in nonstationary noise conditions. Recently, a DFT-subspace-based method was proposed which improves noise PSD estimatio

  7. Low Complexity DFT-Domain Noise PSD Tracking Using High-Resolution Periodograms

    NARCIS (Netherlands)

    Heusdens, R.; Hendriks, R.C.; Jensen, J.; Kjems, U.

    2009-01-01

    Although most noise reduction algorithms are critically dependent on the noise power spectral density (PSD), most procedures for noise PSD estimation fail to obtain good estimates in nonstationary noise conditions. Recently, a DFT-subspace-based method was proposed which improves noise PSD

  8. Noise caused by semiconductor lasers in high-speed fiber-optic links

    DEFF Research Database (Denmark)

    Olsen, C. M.; Stubkjær, Kristian; Olesen, H.

    1989-01-01

    Theoretical and experimental results are presented for the signal-to-noise (S/N) ratio caused by mode partition noise, intensity noise, and reflection-induced noise in optical data links. Under given conditions an additional noise source with a S /N ratio of 20 dB will cause a power penalty of 1 d...

  9. Modeling high signal-to-noise ratio in a novel silicon MEMS microphone with comb readout

    Science.gov (United States)

    Manz, Johannes; Dehe, Alfons; Schrag, Gabriele

    2017-05-01

    Strong competition within the consumer market urges the companies to constantly improve the quality of their devices. For silicon microphones excellent sound quality is the key feature in this respect which means that improving the signal-to-noise ratio (SNR), being strongly correlated with the sound quality is a major task to fulfill the growing demands of the market. MEMS microphones with conventional capacitive readout suffer from noise caused by viscous damping losses arising from perforations in the backplate [1]. Therefore, we conceived a novel microphone design based on capacitive read-out via comb structures, which is supposed to show a reduction in fluidic damping compared to conventional MEMS microphones. In order to evaluate the potential of the proposed design, we developed a fully energy-coupled, modular system-level model taking into account the mechanical motion, the slide film damping between the comb fingers, the acoustic impact of the package and the capacitive read-out. All submodels are physically based scaling with all relevant design parameters. We carried out noise analyses and due to the modular and physics-based character of the model, were able to discriminate the noise contributions of different parts of the microphone. This enables us to identify design variants of this concept which exhibit a SNR of up to 73 dB (A). This is superior to conventional and at least comparable to high-performance variants of the current state-of-the art MEMS microphones [2].

  10. Dynamic Adaptive Median Filter (DAMF for Removal of High Density Impulse Noise

    Directory of Open Access Journals (Sweden)

    Punyaban Patel

    2012-10-01

    Full Text Available This paper proposes a novel adaptive filtering scheme to remove impulse noise from images. The scheme replaces the corrupted test pixel with the median value of non-corrupted neighboring pixels selected from a window dynamically. If the number of non-corrupted pixels in the selected window is not sufficient, a window of next higher size is chosen. Thus window size is automatically adapted based on the density of noise in the image as well as the density of corruption local to a window. As a result window size may vary pixel to pixel while filtering. The scheme is simple to implement and do not require multiple iterations. The efficacy of the proposed scheme is evaluated with respect to subjective as well as objective parameters on standard images on various noise densities. Comparative analysis reveals that the proposed scheme has improved performance over other schemes, preferably in high density impulse noise cases. Further, the computational overhead is also less as compared its competent scheme.

  11. High intensity interior aircraft noise increases the risk of high diastolic blood pressure in Indonesian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Minarma Siagian

    2009-12-01

    Full Text Available Aim: To analyze the effects of aircraft noise, resting pulse rate, and other factors on the risk of high diastolic blood pressure (DBP in Indonesian Air Force pilots.Methods: A nested case-control study was conducted using data extracted from annual medical check-ups indoctrination aerophysiologic training records at the Saryanto Aviation and Aerospace Health Institute (LAKESPRA in Jakarta from January 2003 – September 2008. For analysis of DBP: the case group with DBP ≥ 90 mmHg were compared with contral group with DBP < 79 mmHG. One case matched to 12 controls.Results: Out of 567 pilots, 544 (95.9% had complete medical records. For this analysis there were 40 cases of high DBP and 480 controls for DBP. Pilots exposed to aircraft noise 90-95 dB rather than 70-80 dB had a 2.7-fold increase for high DBP [adjusted odds ratio (ORa = 2.70; 95% confi dence interval (CI = 1.05-6.97]. Pilots with resting pulse rates of ≥ 81/minute rather than ≤ 80/minute had a 2.7-fold increase for high DBP (ORa = 2.66; 95% CI = 1.26-5.61. In terms of total fl ight hours, pilots who had 1401-11125 hours rather than 147-1400 hours had a 3.2-fold increase for high DBP (ORa = 3.18; 95% CI = 1.01-10.03.Conclusion: High interior aircraft noise, high total flight hours,  and high resting pulse rate, increased risk for high DBP. Self assessment of resting pulse rate can be used to control the risk of high DBP. (Med J Indones 2009; 276: 276-82Keywords: diastolic blood pressure, aircraft noise, resting pulse rate, military pilots

  12. High-frequency Audiometry Hearing on Monitoring of Individuals Exposed to Occupational Noise: A Systematic Review.

    Science.gov (United States)

    Antonioli, Cleonice Aparecida Silva; Momensohn-Santos, Teresa Maria; Benaglia, Tatiana Aparecida Silva

    2016-07-01

    The literature reports on high-frequency audiometry as one of the exams used on hearing monitoring of individuals exposed to high sound pressure in their work environment, due to the method́s greater sensitivity in early identification of hearing loss caused by noise. The frequencies that compose the exam are generally between 9 KHz and 20KHz, depending on the equipment. This study aims to perform a retrospective and secondary systematic revision of publications on high-frequency audiometry on hearing monitoring of individuals exposed to occupational noise. This systematic revision followed the methodology proposed in the Cochrane Handbook, focusing on the question: "Is High-frequency Audiometry more sensitive than Conventional Audiometry in the screening of early hearing loss individuals exposed to occupational noise?" The search was based on PubMed data, Base, Web of Science (Capes), Biblioteca Virtual em Saúde (BVS), and in the references cited in identified and selected articles. The search resulted in 6059 articles in total. Of these, only six studies were compatible with the criteria proposed in this study. The performed meta-analysis does not definitively answer the study's proposed question. It indicates that the 16 KHz high frequency audiometry (HFA) frequency is sensitive in early identification of hearing loss in the control group (medium difference (MD = 8.33)), as well as the 4 KHz frequency (CA), this one being a little less expressive (MD = 5.72). Thus, others studies are necessary to confirm the HFA importance for the early screening of hearing loss on individuals exposed to noise at the workplace.

  13. Passenger comfort on high-speed trains: effect of tunnel noise on the subjective assessment of pressure variations.

    Science.gov (United States)

    Sanok, Sandra; Mendolia, Franco; Wittkowski, Martin; Rooney, Daniel; Putzke, Matthias; Aeschbach, Daniel

    2015-01-01

    When passing through a tunnel, aerodynamic effects on high-speed trains may impair passenger comfort. These variations in atmospheric pressure are accompanied by transient increases in sound pressure level. To date, it is unclear whether the latter influences the perceived discomfort associated with the variations in atmospheric pressure. In a pressure chamber of the DLR-Institute of Aerospace Medicine, 71 participants (M = 28.3 years ± 8.1 SD) rated randomised pressure changes during two conditions according to a crossover design. The pressure changes were presented together with tunnel noise such that the sound pressure level was transiently elevated by either +6 dB (low noise condition) or +12 dB (high noise condition) above background noise level (65 dB(A)). Data were combined with those of a recent study, in which identical pressure changes were presented without tunnel noise (Schwanitz et al., 2013, 'Pressure Variations on a Train - Where is the Threshold to Railway Passenger Discomfort?' Applied Ergonomics 44 (2): 200-209). Exposure-response relationships for the combined data set comprising all three noise conditions show that pressure discomfort increases with the magnitude and speed of the pressure changes but decreases with increasing tunnel noise. Practitioner Summary: In a pressure chamber, we systematically examined how pressure discomfort, as it may be experienced by railway passengers, is affected by the presence of tunnel noise during pressure changes. It is shown that across three conditions (no noise, low noise (+6 dB), high noise (+12 dB)) pressure discomfort decreases with increasing tunnel noise.

  14. High-fidelity Simulation of Jet Noise from Rectangular Nozzles . [Large Eddy Simulation (LES) Model for Noise Reduction in Advanced Jet Engines and Automobiles

    Science.gov (United States)

    Sinha, Neeraj

    2014-01-01

    This Phase II project validated a state-of-the-art LES model, coupled with a Ffowcs Williams-Hawkings (FW-H) far-field acoustic solver, to support the development of advanced engine concepts. These concepts include innovative flow control strategies to attenuate jet noise emissions. The end-to-end LES/ FW-H noise prediction model was demonstrated and validated by applying it to rectangular nozzle designs with a high aspect ratio. The model also was validated against acoustic and flow-field data from a realistic jet-pylon experiment, thereby significantly advancing the state of the art for LES.

  15. High-frequency noise in FDSOI MOSFETs: a Monte Carlo investigation

    Science.gov (United States)

    Rengel, Raul; Mateos, Javier; Pardo, Daniel; Gonzalez, Tomas; Martin, Maria Jesus; Dambrine, Gilles; Danneville, Francois; Raskin, Jean-Pierre

    2003-05-01

    Due to the enormous industrial interest of the SOI MOSFET technology, a proper understanding of the physics underlying the behavior of these devices is necessary in order to optimize their high frequency performance. In this work, we study the static, dynamic and noise characteristics of FDSOI MOSFET"s by means of numerical simulations validated by comparison with experimental data. For this purpose, we use a 2D Ensemble Monte Carlo simulator, taking into account, in an appropriate manner, the physical topology of a fabricated 0.25 μm gate-length FDSOI transistor. Important effects appearing in real transistors, such as surface charges, contact resistances, impact ionization phenomena and extrinsic parasitics are included in the simulation. This allows to accurately reproduce the experimental behavior of static and dynamic parameters (output and transference characteristics, gm/ID ratio, capacitances, etc.). Moreover, results are explained by means of internal quantities such as concentration, velocity or energy of carriers. The results of the Monte Carlo simulations for the typical four noise parameters (NFmin, Gass, Rn, Gamma opt) of the 0.25 μm FDSOI MOSFET also show an exceptional agreement with experimental data. Once the reliability of the simulator has been confirmed, a full study of the noise characteristics of the device (noise sources, drain spectral densities, α, β and C parameters, etc.) is performed. Taking advantage of the possibilities of the Monte Carlo method as a pseudo-experimental approach, the influence on these noise characteristics of the variation of some geometry parameters (i.e., downscaling the gate length, thickness of the active layer or inclusion of HALO regions) is evaluated an interpreted in terms of microscopic transport processes.

  16. A method for improving the signal-to-noise ratio in IUE high-dispersion spectra

    Science.gov (United States)

    Welty, Daniel E.

    1988-01-01

    The flat-fielding technique was used to reduce fixed pattern noise in high dispersion IUE spectra, producing improvements in S/N of typically 40 percent compared with un-flat-fielded summed spectra. Weak spectral features may be more reliably identified. Such improvements are noted for specially obtained multiply-exposed images and for singly-exposed images taken from the IUE archives. However it is unclear if the technique is usable or as effective for all spectra.

  17. The Influence of High-Frequency Envelope Information on Low-Frequency Vowel Identification in Noise.

    Directory of Open Access Journals (Sweden)

    Wiebke Schubotz

    Full Text Available Vowel identification in noise using consonant-vowel-consonant (CVC logatomes was used to investigate a possible interplay of speech information from different frequency regions. It was hypothesized that the periodicity conveyed by the temporal envelope of a high frequency stimulus can enhance the use of the information carried by auditory channels in the low-frequency region that share the same periodicity. It was further hypothesized that this acts as a strobe-like mechanism and would increase the signal-to-noise ratio for the voiced parts of the CVCs. In a first experiment, different high-frequency cues were provided to test this hypothesis, whereas a second experiment examined more closely the role of amplitude modulations and intact phase information within the high-frequency region (4-8 kHz. CVCs were either natural or vocoded speech (both limited to a low-pass cutoff-frequency of 2.5 kHz and were presented in stationary 3-kHz low-pass filtered masking noise. The experimental results did not support the hypothesized use of periodicity information for aiding low-frequency perception.

  18. Air flow patterns and noise analysis inside high speed angular contact ball bearings

    Institute of Scientific and Technical Information of China (English)

    翟强; 闫柯; 张优云; 朱永生; 王亚泰

    2015-01-01

    The vortex formed around the rolling ball and the high pressure region formed around the ball−raceway contact zone are the principle factors that barricades the lubricant entering the bearing cavity, and further causes improper lubrication. The investigation of the air phase flow inside the bearing cavity is essential for the optimization of the oil−air two-phase lubrication method. With the revolutionary reference frame describing the bearing motion, a highly precise air phase flow model inside the angular contact ball bearing cavity was build up. Comprehensive factors such as bearing revolution, ball rotation, and cage structure were considered to investigate the influences on the air phase flow and heat transfer efficiency. The aerodynamic noise was also analyzed. The result shows that the ball spinning leads to the pressure rise and uneven pressure distribution. The air phase velocity, pressure and cage heat transfer efficiency increase as the revolving speed increases. The operating noise is largely due to the impact of the high speed external flow on the bearing. When the center of the oil−air outlet fixes near the inner ring, the aerodynamic noise is reduced. The position near the inner ring on the bigger axial side is the ideal position to fix the lubricating device for the angular contact ball bearing.

  19. Noise control of a flow around a cylinder using high-frequency dielectric barrier discharge plasma actuators

    Science.gov (United States)

    Kopiev, V. F.; Belyaev, I. V.; Zaytsev, M. Yu.; Kazansky, P. N.; Kopiev, V. A.; Moralev, I. A.

    2015-03-01

    The effect of high-frequency dielectric barrier discharge plasma actuators on the noise of a flow around a circular cylinder is experimentally studied. It is shown that the plasma actuators are able to reduce the vortex noise of a cylinder within the range of velocities typical for aeroacoustic applications.

  20. Annoyance and activity disturbance induced by high-speed railway and conventional railway noise: a contrastive case study.

    Science.gov (United States)

    Di, Guo-Qing; Lin, Qi-Li; Li, Zheng-Guang; Kang, Jian

    2014-03-07

    High-speed railway (HR, Electrified railway with service speed above 200 km/h.) noise and conventional railway (CR, Electrified railway with service speed under 200 km/h.) noise are different in both time and frequency domain. There is an urgent need to study the influence of HR noise and consequently, develop appropriate noise evaluation index and limits for the total railway noise including HR and CR noise. Based on binaural recording of HR and CR noises in a approximate semi-free field, noise annoyance and activity disturbance induced by maximal train pass-by events in China were investigated through laboratory subjective evaluation. 80 students within recruited 102 students, 40 males and 40 females, 23.9 ± 2.1 years old, were finally selected as the subjects. After receiving noise stimulus via headphone of a binaural audio playback system, subjects were asked to express the annoyance or activity disturbance due to railway noise at a 0-100 numerical scale. The results show that with the same annoyance rating (A) or activity disturbance rating (D), the A-weighted equivalent sound pressure level (LAeq) of CR noise is approximately 7 dB higher than that of HR noise. Linear regression analysis between some acoustical parameters and A (or D) suggests that the coefficient of determination (R2) is higher with the instantaneous fast A-weighted sound pressure level (LAFmax) than that with LAeq. A combined acoustical parameter, LHC = 1.74LAFmax + 0.008LAFmax(Lp-LAeq), where Lp is the sound pressure level, was derived consequently, which could better evaluate the total railway noise, including HR and CR noise. More importantly, with a given LHC, the noise annoyance of HR and CR noise is the same. Among various acoustical parameters including LHC and LAeq, A and D have the highest correlation with LHC. LHC has been proved to be an appropriate index to evaluate the total railway noise, including both HR and CR. However, it should be pointed out that this study provides

  1. Signal and noise of Diamond Pixel Detectors at High Radiation Fluences

    CERN Document Server

    Tsung, Jieh-Wen; Hügging, Fabian; Kagan, Harris; Krüger, Hans; Wermes, Norbert

    2012-01-01

    CVD diamond is an attractive material option for LHC vertex detectors because of its strong radiation-hardness causal to its large band gap and strong lattice. In particular, pixel detectors operating close to the interaction point profit from tiny leakage currents and small pixel capacitances of diamond resulting in low noise figures when compared to silicon. On the other hand, the charge signal from traversing high energy particles is smaller in diamond than in silicon by a factor of about 2.2. Therefore, a quantitative determination of the signal-to-noise ratio (S/N) of diamond in comparison with silicon at fluences in excess of 10$^{15}$ n$_{eq}$ cm$^{-2}$, which are expected for the LHC upgrade, is important. Based on measurements of irradiated diamond sensors and the FE-I4 pixel readout chip design, we determine the signal and the noise of diamond pixel detectors irradiated with high particle fluences. To characterize the effect of the radiation damage on the materials and the signal decrease, the chang...

  2. Quantum limited noise figure operation of high gain erbium doped fiber amplifiers

    DEFF Research Database (Denmark)

    Lumholt, Ole; Povlsen, Jørn Hedegaard; Schüsler, Kim;

    1993-01-01

    powers below -5 dBm, and an improvement of 2.0 dB with a simultaneous gain increase of 4.1 dB is measured relative to a gain-optimized fiber. The optimum isolator location is evaluated for different pump and signal wavelengths in both an Al/Er-doped and a Ge/Er-doped fiber, for pump and signal power......Performance improvements obtained by using an isolator as an amplified-spontaneous-emission-suppressing component within erbium-doped fibers are evaluated. Simultaneous high-gain and near-quantum-limited noise figures can be obtained by such a scheme. The noise figure improves for input signal...... variations and different pump configurations. In all cases the optimum isolator position lies within 10-37% of the total fiber length for small signal operation...

  3. Longitudinal type-line optimization of high-speed train for low aerodynamic noise

    Institute of Scientific and Technical Information of China (English)

    肖友刚; 杨群; 孙亮; 时彧

    2014-01-01

    The basic head shape of high-speed train is determined by its longitudinal type-line (LTL), so it is crucial to optimize its aerodynamic performance. Based on the parametric modeling of LTL constructed by non-uniform relational B-spline (NURBS) and the fluctuation pressure obtained by large eddy simulation (LES), the Kriging surrogate model (KSM) of LTL was constructed for low aerodynamic noise, and the accuracy of the KSM was improved gradually by adding the sample point with maximum expected improvement (EI) and the optimal point from optimization. The optimal objective was searched with genetic algorithm (GA). The results show that the total fluctuation pressure level (FPL) of the optimal LTL can be 8.7 dB less than that of original one, and the shape optimization method is feasible for low aerodynamic noise design.

  4. Effects of Noise and Absorption on High Frequency Measurements of Acoustic-Backscatter from Fish

    Directory of Open Access Journals (Sweden)

    Masahiko Furusawa

    2015-01-01

    Full Text Available Quantitative echosounders operating at multiple frequencies (e.g., 18, 38, 70, 120, 200, 333, and 710 kHz are often used to observe fish and zooplankton and identify their species. At frequencies above 100 kHz, the absorption attenuation increases rapidly and decreases the signal-to-noise ratio (SNR. Also, incomplete compensation for the attenuation may result in measurement error. This paper addresses the effects of the attenuation and noise on high frequency measurements of acoustic backscatter from fish. It is shown that measurements of a fish with target strength of −40 dB at 200 m depth are limited by SNR to frequencies up to about 100 kHz. Above 100 kHz, absorption coefficients must be matched to local environmental conditions.

  5. Depict noise-driven nonlinear dynamic networks from output data by using high-order correlations

    CERN Document Server

    Chen, Yang; Chen, Tianyu; Wang, Shihong; Hu, Gang

    2016-01-01

    Many practical systems can be described by dynamic networks, for which modern technique can measure their output signals, and accumulate extremely rich data. Nevertheless, the network structures producing these data are often deeply hidden in these data. Depicting network structures by analysing the available data turns to be significant inverse problems. On one hand, dynamics are often driven by various unknown facts, called noises. On the other hand, network structures of practical systems are commonly nonlinear, and different nonlinearities can provide rich dynamic features and meaningful functions of realistic networks. So far, no method, both theoretically or numerically, has been found to systematically treat the both difficulties together. Here we propose to use high-order correlation computations (HOCC) to treat nonlinear dynamics; use two-time correlations to treat noise effects; and use suitable basis and correlator vectors to unifiedly depict all dynamic nonlinearities and topological interaction l...

  6. A High Input Impedance Low Noise Integrated Front-End Amplifier for Neural Monitoring.

    Science.gov (United States)

    Zhou, Zhijun; Warr, Paul A

    2016-12-01

    Within neural monitoring systems, the front-end amplifier forms the critical element for signal detection and pre-processing, which determines not only the fidelity of the biosignal, but also impacts power consumption and detector size. In this paper, a novel combined feedback loop-controlled approach is proposed to compensate for input leakage currents generated by low noise amplifiers when in integrated circuit form alongside signal leakage into the input bias network. This loop topology ensures the Front-End Amplifier (FEA) maintains a high input impedance across all manufacturing and operational variations. Measured results from a prototype manufactured on the AMS 0.35 [Formula: see text] CMOS technology is provided. This FEA consumes 3.1 [Formula: see text] in 0.042 [Formula: see text], achieves input impedance of 42 [Formula: see text], and 18.2 [Formula: see text] input-referred noise.

  7. Thermal Analysis of Multi-MW Two-Level Generator Side Converters with Reduced Common-Mode-Voltage Modulation Methods for Wind Turbines

    DEFF Research Database (Denmark)

    Qin, Zian; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    Thermal performance is one of the main indicators of power converter, since it is related to both the cost of cooling system and the reliability of the power converter. Moreover, the common-mode voltage in motor driver may damage the bearing of the motor and also cause failure. Therefore, both...

  8. Low-noise multichannel ASIC for high count rate X-ray diffractometry applications

    Energy Technology Data Exchange (ETDEWEB)

    Szczygiel, R. [AGH University of Science and Technology, Department of Measurement and Instrumentation, al. Mickiewicza 30, Krakow (Poland)], E-mail: robert.szczygiel@agh.edu.pl; Grybos, P.; Maj, P. [AGH University of Science and Technology, Department of Measurement and Instrumentation, al. Mickiewicza 30, Krakow (Poland); Tsukiyama, A.; Matsushita, K.; Taguchi, T. [Rigaku Corporation, 3-9-12 Matsubara-cho, Akishima-shi, Tokyo (Japan)

    2009-08-01

    RG64 is a 64-channel ASIC designed for the silicon strip detector readout and optimized for high count rate X-ray imaging applications. In this paper we report on the test results referring to the RG64 noise level, channel uniformity and the operation with a high rate of input signals. The parameters of the RG64-based diffractometry system are compared with the ones based on the scintillation counter. Diffractometry measurement results with silicon strip detectors of different strip lengths and strip pitch are also presented.

  9. Fast cavity-enhanced atom detection with low noise and high fidelity

    Science.gov (United States)

    Goldwin, J.; Trupke, M.; Kenner, J.; Ratnapala, A.; Hinds, E.A.

    2011-01-01

    Cavity quantum electrodynamics describes the fundamental interactions between light and matter, and how they can be controlled by shaping the local environment. For example, optical microcavities allow high-efficiency detection and manipulation of single atoms. In this regime, fluctuations of atom number are on the order of the mean number, which can lead to signal fluctuations in excess of the noise on the incident probe field. Here we demonstrate, however, that nonlinearities and multi-atom statistics can together serve to suppress the effects of atomic fluctuations when making local density measurements on clouds of cold atoms. We measure atom densities below 1 per cavity mode volume near the photon shot-noise limit. This is in direct contrast to previous experiments where fluctuations in atom number contribute significantly to the noise. Atom detection is shown to be fast and efficient, reaching fidelities in excess of 97% after 10 μs and 99.9% after 30 μs. PMID:21829180

  10. Validation and application of an high-order spectral difference method for flow induced noise simulation

    KAUST Repository

    Parsani, Matteo

    2011-09-01

    The main goal of this paper is to develop an efficient numerical algorithm to compute the radiated far field noise provided by an unsteady flow field from bodies in arbitrary motion. The method computes a turbulent flow field in the near fields using a high-order spectral difference method coupled with large-eddy simulation approach. The unsteady equations are solved by advancing in time using a second-order backward difference formulae scheme. The nonlinear algebraic system arising from the time discretization is solved with the nonlinear lowerupper symmetric GaussSeidel algorithm. In the second step, the method calculates the far field sound pressure based on the acoustic source information provided by the first step simulation. The method is based on the Ffowcs WilliamsHawkings approach, which provides noise contributions for monopole, dipole and quadrupole acoustic sources. This paper will focus on the validation and assessment of this hybrid approach using different test cases. The test cases used are: a laminar flow over a two-dimensional (2D) open cavity at Re = 1.5 × 10 3 and M = 0.15 and a laminar flow past a 2D square cylinder at Re = 200 and M = 0.5. In order to show the application of the numerical method in industrial cases and to assess its capability for sound field simulation, a three-dimensional turbulent flow in a muffler at Re = 4.665 × 10 4 and M = 0.05 has been chosen as a third test case. The flow results show good agreement with numerical and experimental reference solutions. Comparison of the computed noise results with those of reference solutions also shows that the numerical approach predicts noise accurately. © 2011 IMACS.

  11. Noise suppression by noise

    OpenAIRE

    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.

  12. High-Lift Propeller Noise Prediction for a Distributed Electric Propulsion Flight Demonstrator

    Science.gov (United States)

    Nark, Douglas M.; Buning, Pieter G.; Jones, William T.; Derlaga, Joseph M.

    2017-01-01

    Over the past several years, the use of electric propulsion technologies within aircraft design has received increased attention. The characteristics of electric propulsion systems open up new areas of the aircraft design space, such as the use of distributed electric propulsion (DEP). In this approach, electric motors are placed in many different locations to achieve increased efficiency through integration of the propulsion system with the airframe. Under a project called Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR), NASA is designing a flight demonstrator aircraft that employs many "high-lift propellers" distributed upstream of the wing leading edge and two cruise propellers (one at each wingtip). As the high-lift propellers are operational at low flight speeds (take-off/approach flight conditions), the impact of the DEP configuration on the aircraft noise signature is also an important design consideration. This paper describes efforts toward the development of a mulit-fidelity aerodynamic and acoustic methodology for DEP high-lift propeller aeroacoustic modeling. Specifically, the PAS, OVERFLOW 2, and FUN3D codes are used to predict the aerodynamic performance of a baseline high-lift propeller blade set. Blade surface pressure results from the aerodynamic predictions are then used with PSU-WOPWOP and the F1A module of the NASA second generation Aircraft NOise Prediction Program to predict the isolated high-lift propeller noise source. Comparisons of predictions indicate that general trends related to angle of attack effects at the blade passage frequency are captured well with the various codes. Results for higher harmonics of the blade passage frequency appear consistent for the CFD based methods. Conversely, evidence of the need for a study of the effects of increased azimuthal grid resolution on the PAS based results is indicated and will be pursued in future work. Overall, the results indicate that the computational

  13. Observation of the Fundamental Nyquist Noise Limit in an Ultra-High $Q$-Factor Cryogenic Bulk Acoustic Wave Cavity

    CERN Document Server

    Goryachev, Maxim; van Kann, Frank; Galliou, Serge; Tobar, Michael E

    2014-01-01

    Thermal Nyquist noise fluctuations of high-$Q$ Bulk Acoustic Wave (BAW) cavities have been observed at cryogenic temperatures with a DC Superconducting Quantum Interference Device (SQUID) amplifier. High $Q$ modes with bandwidths of few tens of milliHz produce thermal fluctuations with a Signal-To-Noise ratio of up to 23dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high ($Q>10^8$ at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.

  14. High Intensity Pressure Noise Transmission in Human Ear: A Three Dimensional Simulation Study

    Science.gov (United States)

    Hawa, Takumi; Gan, Rong; Leckness, Kegan

    2015-03-01

    High intensity pressure noise generated by explosions and jet engines causes auditory damage and hearing loss of the military service personals, which are the most common disabilities in the veterans. Authors have investigated the high intensity pressure noise transmission from the ear canal to middle ear cavity. A fluid-structure interaction with a viscoelastic model for the tympanic membrane (TM) as well as the ossicular chain has been considered in the study. For the high intensity pressure simulation the geometry of the ear was based on a 3D finite element (FE) model of the human ear reported by Gan et al. (Ann Biomed Eng 2004). The model consists of the ear canal, TM, ossicular chain, and the middle ear cavity. The numerical approach includes two steps: 1) FE based finite-volume method simulation to compute pressure distributions in the ear canal and the middle ear cavity using CFX; and 2) FE modeling of TM and middle ear ossicles in response to high intensity sound using multi-physics analysis in ANSYS. The simulations provide the displacement of the TM/ossicular chain and the pressure fields in the ear canal and the middle ear cavity. These results are compared with human temporal bone experimental data obtained in our group. This work was supported by DOD W81XWH-14-1-0228.

  15. Ambient Seismic Noise Tomography of a Loess High Bank at Dunaszekcső (Hungary)

    Science.gov (United States)

    Szanyi, Gyöngyvér; Gráczer, Zoltán; Győri, Erzsébet; Kaláb, Zdeněk; Lednická, Markéta

    2016-08-01

    Loess high banks along the right side of the Danube in Hungary are potential subjects of landslides. Small scale ambient seismic noise tomography was used at the Dunaszekcső high bank. The aim of the study was to map near surface velocity anomalies since we assume that the formation of tension cracks—which precede landslides—are represented by low velocities. Mapping Rayleigh wave group velocity distribution can help to image intact and creviced areas and identify the most vulnerable sections. The study area lies at the top of the Castle Hill of Dunaszekcső, which was named after Castellum Lugio, a fortress of Roman origin. The presently active head scarp was formed in April 2011, and our study area was chosen to be at its surroundings. Cross-correlation functions of ambient noise recordings were used to retrieve the dispersion curves, which served as the input of the group velocity tomography. Phase cross-correlation and time-frequency phase weighted stacking was applied to calculate the cross-correlation functions. The average Rayleigh wave group velocity at the loess high bank was found to be 171 ms^{-1}. The group velocity map at a 0.1 s period revealed a low-velocity region, whose location coincides with a highly creviced area, where slope failure takes place along a several meter wide territory. Another low velocity region was found, which might indicate a previously unknown loosened domain. The highest velocities were observed at the supposed remnants of Castellum Lugio.

  16. A low noise and high precision linear power supply with thermal foldback protection

    Science.gov (United States)

    Carniti, P.; Cassina, L.; Gotti, C.; Maino, M.; Pessina, G.

    2016-05-01

    A low noise and high precision linear power supply was designed for use in rare event search experiments with macrobolometers. The circuit accepts at the input a "noisy" dual supply voltage up to ±15 V and gives at the output precise, low noise, and stable voltages that can be set between ±3.75 V and ±12.5 V in eight 1.25 V steps. Particular care in circuit design, component selection, and proper filtering results in a noise spectral density of 50 nV / √{ Hz } at 1 Hz and 20 nV / √{ Hz } white when the output is set to ±5 V. This corresponds to 125 nV RMS (0.8 μV peak to peak) between 0.1 Hz and 10 Hz, and 240 nV RMS (1.6 μV peak to peak) between 0.1 Hz and 100 Hz. The power supply rejection ratio (PSRR) of the circuit is 100 dB at low frequency, and larger than 40 dB up to high frequency, thanks to a proper compensation design. Calibration allows to reach a precision in the absolute value of the output voltage of ±70 ppm, or ±350 μV at ±5 V, and to reduce thermal drifts below ±1 ppm/∘C in the expected operating range. The maximum peak output current is about 6 A from each output. An original foldback protection scheme was developed that dynamically limits the maximum output current to keep the temperature of the output transistors within their safe operating range. An add-on card based on an ARM Cortex-M3 microcontroller is devoted to the monitoring and control of all circuit functionalities and provides remote communication via CAN bus.

  17. Low-noise moisture meter with high-speed LED techniques

    Science.gov (United States)

    Aikio, Rami; Lindström, Hannu; Suopajärvi, Pekka; Malinen, Jouko; Mäntylä, Markku

    2010-04-01

    Near infrared (NIR) spectroscopy can provide inexpensive, rapid and contact-free chemical content measurements for on-line, hand-held and laboratory applications. Traditionally multiwavelength NIR analyzers are based on incandescent lamp light sources with rotating filter wheels, even though designs relying on lamp technology and moving parts mean larger size, require frequent maintenance and eventually limit measurement speed of the system. Today, optical power and available wavelength range of LEDs enable their use in chemical content analyzers. In this publication, a paper moisture meter with high speed LED techniques is presented. A prototype developed at VTT utilizes an extended InGaAs detector to measure diffuse reflection at four NIR wavelengths ranging from 1.2 to 2.1 μm. Source LED currents are amplitude modulated with fixed sinusoidal frequencies. Optical signals at each wavelength are demodulated from the detector signal using real-time digital lock-in detection method on an FPGA. Moisture content is calculated and displayed on the embedded platform. The design allows very high speed operation, where the result is updated every 1 ms. Performance of the prototype system was studied by measuring a set of known sealed paper samples. Paper moisture measurement accuracy was 0.14, repeatability 0.01 and 2σ noise 0.04 moisture percent. Laboratory tests showed that channel crosstalk after detection is below background noise level. The measured signal-to-noise ratios per channel were 70 - 85 dB when all LEDs were on. The overall performance equals the level of incandescent lamp based on-line moisture meters currently in use in paper mill and process automation. The developed system forms a good basis also for other content measurements.

  18. Imaging the lithospheric structure of the High Lava Plains, Oregon with ambient noise tomography

    Science.gov (United States)

    Hanson-Hedgecock, S.; Wagner, L. S.; Fouch, M. J.

    2010-12-01

    We use ambient noise tomography (ANT) to image the 3-D structure of the crust and uppermost mantle beneath the High Lava Plains, Oregon using data from ~300 broadband stations of the High Lava Plains seismic experiment and the EarthScope/USArray Transportable Array (TA). The High Lava Plains consists of WNW progressive silicic volcanism, beginning ~14.5 Ma near the Owyhee Plateau and continuing to ~1.5 Ma in outpourings near the Newberry caldera. Superimposed basaltic volcanism has occurred along the hotspot since ~10.5 Ma. The Snake River Plain’s volcanism has been associated with a Yellowstone hot spot due to its alignment with North American plate motion, but the High Lava Plains volcanism does not have a comparably straightforward explanation. Recent results from a surface wave tomographic study of the Yellowstone/Snake River Plains (YSRP) reveal a discrete low velocity anomaly in the upper mantle that shallows to the northeast, consistent with plate motion over a stationary heat source. The same study shows a discontinuous low velocity anomaly beneath the High Lava Plains, indicating a less continuous east to west heat source along the HLP volcanic track. To better resolve the shallow velocity structure beneath the High Lava Plains, ANT is used to determine phase velocity maps at periods of <8s to 40s. At periods between 20 and 40s the ambient noise phase velocity maps complement the surface wave tomographic results and provide additional constraints on velocity structure. ANT has improved lateral resolution, compared to traditional surface wave tomography, because of the more homogenous azimuthal content of ambient noise. Vertical resolution of shallower crustal structures is also improved; ANT is able to resolve velocity structures at periods below 20s. Lastly, the dense station spacing of the combined HLP and TA dataset allows the shallow structure of the High Lava Plains to be imaged in more detail than previous ANT studies that focused on the entire

  19. Application of High Order X-LMS Filter for Active Noise Control

    Directory of Open Access Journals (Sweden)

    N.V.K.Mahalakshmi

    2014-06-01

    Full Text Available In this paper active noise is controlled by using higher order X-LMS (least mean square filter. This technique is based on X-NLMS (normalized least mean square, also known as traditional acoustic noise cancellation (ANC scheme. It cancels the wideband noise from the corrupted speech signal. The active noise reducing headphone is probably the most successful application of active control of sound – the technology of cancelling sound with sound i.e., by using anti-noise signal. This report presents an outlined technical review of noise cancellation in headphones. The principles of passive noise attenuation are presented after which active attenuation is introduced showing how the two complement the attenuation performance. In real-time environment, the number of different applications in which adaptive techniques are being successfully used that are echo cancellation, equalization of dispersive channels, system identification, signal enhancement, noise cancelling and control.

  20. Design and noise analysis of a fully-differential charge pump for phase-locked loops

    Institute of Scientific and Technical Information of China (English)

    Gong Zhichao; Lu Lei; Liao Youchun; Tang Zhangwen

    2009-01-01

    A fully-differential charge pump (FDCP) with perfect current matching and low output current noise is realized for phase-locked loops (PLLs). An easily stable common-mode feedback (CMFB) circuit which can handle high input voltage swing is proposed. Current mismatch and current noise contribution from the CMFB circuit is minimized. In order to optimize PLL phase noise, the output current noise of the FDCP is analyzed in detail and calculated with the sampling principle. The calculation result agrees well with the simulation. Based on the noise analysis, many methods to lower output current noise of the FDCP are discussed. The fully-differential charge pump is integrated into a 1-2 GHz frequency synthesizer and fabricated in an SMIC CMOS 0.18 μm process. The measured output reference spur is -64 dBc to -69 dBc. The in-band and out-band phase noise is -95 dBc/Hz at 3 kHz frequency offset and -123 dBc/Hz at 1 MHz frequency offset respectively.

  1. Improved energy resolution of highly segmented HPGe detectors by noise reduction

    Energy Technology Data Exchange (ETDEWEB)

    Wiens, A.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Hess, H.; Pascovici, Gh.; Reiter, P. [Institut fuer Kernpyhsik, Koeln (Germany); Bazzacco, D.; Farnea, E.; Michelagnoli, C.; Recchia, F. [INFN, Sezione di Padova, Padova (Italy); Collaboration: for the AGATA Collaboration

    2013-04-15

    Built-in redundancies in highly segmented high-purity Ge detectors are exploited to increase the energy resolution of these semiconductor devices for detection of electromagnetic radiation in the X-ray and {gamma}-ray regime. The information of the two electronically decoupled independent measurements, the cathode and the anode electrodes, provides an improved signal-to-noise ratio through a combination of the individually measured signals performed on an event-by-event basis. The average energy resolution values of the AGATA triple cluster detector for an energy deposition of 60keV was measured to be 1.1 keV (FWHM) for the 36 segments and 1.2 keV for the core. The averaged signals of the core and the segments show an improved resolution value of 0.87 keV which is close to the expected theoretical limit. At higher {gamma}-ray energy the averaging technique allows for an enhanced energy resolution with a FWHM of 2.15keV at 1.3MeV. By means of the position sensitive operation of AGATA a new value for the Fano factor was determined and the noise contributions to the FWHM of a {gamma}-ray peak separated. (orig.)

  2. Detecting Free-Mass Common-Mode Motion Induced by Incident Gravitational Waves: Testing General Relativity and Source Direction via Fox-Smith and Michelson Interferometers

    CERN Document Server

    Tobar, Michael Edmund; Kuroda, Kazuaki

    2009-01-01

    In this paper we show that information on both the differential and common mode free-mass response to a gravitational wave can provide important information on discriminating the direction of the gravitational wave source and between different theories of gravitation. The conventional Michelson interferometer scheme only measures the differential free-mass response. By changing the orientation of the beam splitter, it is possible to configure the detector so it is sensitive to the common-mode of the free-mass motion. The proposed interferometer is an adaptation of the Fox-Smith interferometer. A major limitation to the new scheme is its enhanced sensitivity to laser frequency fluctuations over the conventional, and we propose a method of canceling these fluctuations. The configuration could be used in parallel to the conventional differential detection scheme with a significant sensitivity and bandwidth.

  3. Approaches to Suppressing Shaft Voltage in Brushless DC Motor Driven by PWM Inverter Based on Ungrounded Common-Mode Equivalent Circuit

    Science.gov (United States)

    Maetani, Tatsuo; Isomura, Yoshinori; Watanabe, Akihiko; Iimori, Kenichi; Morimoto, Shigeo

    This paper describes an ungrounded common-mode equivalent circuit for a motor driven by a voltage-source PWM inverter. When the capacitance of the rotor was is small, the reversal of the polarities of the common-mode voltage and shaft voltage is observed. In order to model this reversal, a bridge-type equivalent circuit is proposed. On the basis of calculations and experiment, it is found the values and polarity of the shaft voltage can be are accurately determined with the proposed equivalent circuit. Furthermore, the capacitance value of the insulated rotor required to make the shaft voltage equal to or less than the dielectric breakdown voltage of the bearing grease is obtained.

  4. Switched-capacitor multiply-by-two amplifier with reduced capacitor mismatches sensitivity and full swing sample signal common-mode voltage

    Institute of Scientific and Technical Information of China (English)

    Xu Xinnan; Yao Suying; Xu Jiangtao; Nie Kaiming

    2012-01-01

    A switched-capacitor amplifier with an accurate gain of two that is insensitive to component mismatch is proposed.This structure is based on associating two sets of two capacitors in cross series during the amplification phase.This circuit permits the common-mode voltage of the sample signal to reach full swing.Using the chargecomplement technique,the proposed amplifier can reduce the impact of parasitic capacitors on the gain accuracy effectively.Simulation results show that as sample signal common-mode voltage changes,the difference between the minimum and maximum gain error is less than 0.03%.When the capacitor mismatch is increased from 0 to 0.2%,the gain error is deteriorated by 0.00015 %.In all simulations,the gain of amplifier is 69 dB.

  5. Harmonic Retrieval Embedded in Hybrid Colored Noise: a Novel Pisarenko Method Based on Cross-high-order Cumulant

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Spectral estimation method is an effective method in the case of parameter estimation of sinusoid signal in noises.It always applies cross-spectral estimation theory and high-order self-spectral estimation methods up to now.Yule-Walker equation based on cross-fourth-order cumulant is developed and Pisarenko method is provided in this paper.Simulation results show that the method is effective to retrieve sinusoid signal frequencies from hybrid colored noises and has good performance.

  6. Comparison of Two Dose-response Relationship of Noise Exposure Evaluation Results with High Frequency Hearing Loss

    Institute of Scientific and Technical Information of China (English)

    Hua Zhang; Nan Li; Qiu-Ling Yang; Wei Qiu; Liang-Liang Zhu; Li-Yuan Tao; Robert I Davis

    2015-01-01

    Background:Complex noise and its relation to hearing loss are difficult to measure and evaluate.In complex noise measurement,individual exposure results may not accurately represent lifetime noise exposure.Thus,the mean LAeq,8 h values of individuals in the same workgroup were also used to represent LAeq,8h in our study.Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did.Methods:A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE) and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China.We used a personal noise dosimeter and a questionnaire to determine the workers' occupational noise exposure levels and exposure times,respectively.A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance.Results:We observed that 88.3% of workers were exposed to more than 85 dB(A) of occupational noise (mean:89.3 ± 4.2 dB(A)).The personal CNE (CNEp) and workgroup CNE (CNEg) were 100.5 ± 4.7 dB(A) and 100.5 ± 2.9 dB(A),respectively.In the binary logistic regression analysis,we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable.The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable.Furthermore,we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was.The CNEg model was better than the CNEp model.In this circumstance,we can measure some subjects instead of the whole workgroup and save manpower.Conclusions:In a complex noise environment,the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.

  7. Comparison of Two Dose-response Relationship of Noise Exposure Evaluation Results with High Frequency Hearing Loss

    Directory of Open Access Journals (Sweden)

    Hua Zhang

    2015-01-01

    Full Text Available Background: Complex noise and its relation to hearing loss are difficult to measure and evaluate. In complex noise measurement, individual exposure results may not accurately represent lifetime noise exposure. Thus, the mean L Aeq,8 h values of individuals in the same workgroup were also used to represent L Aeq,8 h in our study. Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did. Methods: A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China. We used a personal noise dosimeter and a questionnaire to determine the workers′ occupational noise exposure levels and exposure times, respectively. A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance. Results: We observed that 88.3% of workers were exposed to more than 85 dB(A of occupational noise (mean: 89.3 ± 4.2 dB(A. The personal CNE (CNEp and workgroup CNE (CNEg were 100.5 ± 4.7 dB(A and 100.5 ± 2.9 dB(A, respectively. In the binary logistic regression analysis, we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable. The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable. Furthermore, we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was. The CNEg model was better than the CNEp model. In this circumstance, we can measure some subjects instead of the whole workgroup and save manpower. Conclusions: In a complex noise environment, the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.

  8. Development of a shock noise prediction code for high-speed helicopters - The subsonically moving shock

    Science.gov (United States)

    Tadghighi, H.; Holz, R.; Farassat, F.; Lee, Yung-Jang

    1991-01-01

    A previously defined airfoil subsonic shock-noise prediction formula whose result depends on a mapping of the time-dependent shock surface to a time-independent computational domain is presently coded and incorporated in the NASA-Langley rotor-noise prediction code, WOPWOP. The structure and algorithms used in the shock-noise prediction code are presented; special care has been taken to reduce computation time while maintaining accuracy. Numerical examples of shock-noise prediction are presented for hover and forward flight. It is confirmed that shock noise is an important component of the quadrupole source.

  9. 空空导弹冗余系统共模失效%Approach of Common Mode Failure Analysis in Redundant System of Air-to-Air Missile

    Institute of Scientific and Technical Information of China (English)

    王丽丽; 周光巍; 王俊华

    2011-01-01

    为避免空空导弹冗余系统产生共模失效,提高产品可靠性和安全性。在研究共模失效分析方法的基础上,结合空空导弹的研制特点,对某型空空导弹电源组件点火电路冗余系统共模故障进行了定性分析,识别了点火电路中的共模故障,分析了故障原因和耦合因素,并提出了相应的改进措施。%In order to avoiding common mode failure of the air-to-air missile, and improving the reliability and safety of the product, combine the developing character of the air-to-air missile, made a qualitative a- nalysis of the common mode failure in the redundant system of a type air-to-air missile power supply module igniting circuit based on the study of the method of common mode failure analysis, identified the com- mon mode failure of the equipment, analyzed the cause of failure and the coupling factor, put forward improvement measures.

  10. Reducing Magnetic Noise of an Unmanned Aerial Vehicle for High-Quality Magnetic Surveys

    Directory of Open Access Journals (Sweden)

    Boris Sterligov

    2016-01-01

    Full Text Available The use of light and ultralight unmanned aerial vehicles (UAVs for magnetic data acquisition can be efficient for resolving multiple geological and engineering tasks including geological mapping, ore deposits’ prospecting, and pipelines’ monitoring. The accuracy of the aeromagnetic data acquired using UAV depends mainly on deviation noise of electric devices (engine, servos, etc.. The goal of this research is to develop a nonmagnetic unmanned aerial platform (NUAP for high-quality magnetic surveys. Considering parameters of regional and local magnetic survey, a fixed-wing UAV suits geological tasks better for plain area and copter type for hills and mountains. Analysis of the experimental magnetic anomalies produced by a serial light fixed-wing UAV and subsequent magnetic and aerodynamic modeling demonstrates a capacity of NUAP with internal combustion engine carrying an atomic magnetic sensor mounted on the UAV wings to facilitate a high-quality magnetic survey.

  11. Method to Produce Flexible Ceramic Thermal Protection System Resistant to High Aeroacoustic Noise

    Science.gov (United States)

    Sawko, Paul M. (Inventor); Calamito, Dominic P. (Inventor); Jong, Anthony (Inventor)

    1997-01-01

    A method of producing a three dimensional angle interlock ceramic fiber which is stable to high aeroacoustic noise of about 170 decibels and to high temperatures of about 2500 F is disclosed. The method uses multiple separate strands of a ceramic fiber or ceramic tow suitable for weaving having multiple warp fibers and multiple fill fibers woven with a modified fly-shuttle loom or rapier shuttleless loom which has nip rolls, a modified fabric advancement mechanism and at least eight harnesses in connection with a Dobby pattern chain utilizing sufficient heddles for each warp fiber and a reed which accommodates at least 168 ends per inch. The method produces a multilayered top fabric, rib fabric and single-layered bottom fabric.

  12. High-fidelity two-qubit gates via dynamical decoupling of local 1 /f noise at the optimal point

    Science.gov (United States)

    D'Arrigo, A.; Falci, G.; Paladino, E.

    2016-08-01

    We investigate the possibility of achieving high-fidelity universal two-qubit gates by supplementing optimal tuning of individual qubits with dynamical decoupling (DD) of local 1 /f noise. We consider simultaneous local pulse sequences applied during the gate operation and compare the efficiencies of periodic, Carr-Purcell, and Uhrig DD with hard π pulses along two directions (πz /y pulses). We present analytical perturbative results (Magnus expansion) in the quasistatic noise approximation combined with numerical simulations for realistic 1 /f noise spectra. The gate efficiency is studied as a function of the gate duration, of the number n of pulses, and of the high-frequency roll-off. We find that the gate error is nonmonotonic in n , decreasing as n-α in the asymptotic limit, α ≥2 , depending on the DD sequence. In this limit πz-Urhig is the most efficient scheme for quasistatic 1 /f noise, but it is highly sensitive to the soft UV cutoff. For small number of pulses, πz control yields anti-Zeno behavior, whereas πy pulses minimize the error for a finite n . For the current noise figures in superconducting qubits, two-qubit gate errors ˜10-6 , meeting the requirements for fault-tolerant quantum computation, can be achieved. The Carr-Purcell-Meiboom-Gill sequence is the most efficient procedure, stable for 1 /f noise with UV cutoff up to gigahertz.

  13. In situ electrochemical impedance and noise measurements of corroding stainless steel in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Effect of low light and high noise on behavioural activity, physiological indicators of stress and production in laying hens.

    Science.gov (United States)

    O'connor, E A; Parker, M O; Davey, E L; Grist, H; Owen, R C; Szladovits, B; Demmers, T G M; Wathes, C M; Abeyesinghe, S M

    2011-12-01

    1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively little is known about whether these conditions, particularly in combination, have any effect on welfare or egg production. 2. The study was designed to investigate whether chronic exposure to continuous noise (60 dB(A) vs. 80 dB(A)) and/or light intensity (150 lux vs. 5 lux) during the critical period of coming into lay (16-24 weeks of age) influenced behaviour (activity, resting and feather maintenance), physiological stress (plasma corticosterone and heterophil to lymphocyte ratio) and production (number and weight of eggs laid) in laying hens. 3. Hens in the low light pens were less active and preened and dust-bathed more than those housed in 150 lux; hens in the high noise pens rested more frequently than those in quieter pens. 4. There was no evidence that chronic exposure to low light or high noise caused appreciable physiological stress but egg production was affected by these conditions. Hens kept in pens with low light or high noise laid fewer eggs per day than those kept in high light or low noise pens. These effects were additive, so that the fewest eggs were laid by hens subject to both low light and high noise. 5. These results show that low light intensity and continual high background noise have a detrimental effect on egg production in the early laying phase as well as influencing the time allocated to different behaviours. However there was no strong evidence for a physiological stress response to either of these conditions or their combination.

  15. Eliminating common-mode voltage of NPC/H inverter based on modified SVPWM strategy%基于改进型SVPWM的五电平NPC/H变流器共模电压抑制技术研究

    Institute of Scientific and Technical Information of China (English)

    章勇高; 龙立中; 陈长龙; 邝光健

    2012-01-01

    reference voltage. Therefore, a five-level SVPWM control strategy with high complexity can be accomplished briefly by two separated three-level SVPWM control strategy. Besides, one equivalent inverter always operates with zero common mode voltage for suppressing CMV and the other one operates with conventional three-level SVPWM control. Theoretical analysis on DC supply voltage utilization and maximum amplitude of CMV( common-mode voltage) was carried out, and it was compared with the traditional SVPWM and zero CMV. Theoretical analysis and simulation results show that the common-mode voltage of five-level inverter decreases about 60% comparing with traditional SVPWM, and the DC voltage utilization ratio increases about 4% comparing with zero common mode voltage strategy. The results validate the proposed SVPWM strategy can suppress the common mode voltage of inverter and maintain the better character of DC voltage utilization ratio.

  16. High-Frequency Transcranial Random Noise Stimulation Enhances Perception of Facial Identity.

    Science.gov (United States)

    Romanska, Aleksandra; Rezlescu, Constantin; Susilo, Tirta; Duchaine, Bradley; Banissy, Michael J

    2015-11-01

    Recently, a number of studies have demonstrated the utility of transcranial current stimulation as a tool to facilitate a variety of cognitive and perceptual abilities. Few studies, though, have examined the utility of this approach for the processing of social information. Here, we conducted 2 experiments to explore whether a single session of high-frequency transcranial random noise stimulation (tRNS) targeted at lateral occipitotemporal cortices would enhance facial identity perception. In Experiment 1, participants received 20 min of active high-frequency tRNS or sham stimulation prior to completing the tasks examining facial identity perception or trustworthiness perception. Active high-frequency tRNS facilitated facial identity perception, but not trustworthiness perception. Experiment 2 assessed the spatial specificity of this effect by delivering 20 min of active high-frequency tRNS to lateral occipitotemporal cortices or sensorimotor cortices prior to participants completing the same facial identity perception task used in Experiment 1. High-frequency tRNS targeted at lateral occipitotemporal cortices enhanced performance relative to motor cortex stimulation. These findings show that high-frequency tRNS to lateral occipitotemporal cortices produces task-specific and site-specific enhancements in face perception.

  17. Noise-free high-efficiency photon-number-resolving detectors

    CERN Document Server

    Rosenberg, D; Miller, A J; Nam, S W; Rosenberg, Danna; Lita, Adriana E.; Miller, Aaron J.; Nam, Sae Woo

    2005-01-01

    High-efficiency optical detectors that can determine the number of photons in a pulse of monochromatic light have applications in a variety of physics studies, including post-selection-based entanglement protocols for linear optics quantum computing and experiments that simultaneously close the detection and communication loopholes of Bell's inequalities. Here we report on our demonstration of fiber-coupled, noise-free, photon-number-resolving transition-edge sensors with 88% efficiency at 1550 nm. The efficiency of these sensors could be made even higher at any wavelength in the visible and near-infrared spectrum without resulting in a higher dark-count rate or degraded photon-number resolution.

  18. Annoyance to Noise Produced by a Distributed Electric Propulsion High-Lift System

    Science.gov (United States)

    Rizzi, Stephen A.; Palumbo, Daniel L.; Rathsam, Jonathan; Christian, Andrew; Rafaelof, Menachem

    2017-01-01

    A psychoacoustic test was performed using simulated sounds from a distributed electric propulsion aircraft concept to help understand factors associated with human annoyance. A design space spanning the number of high-lift leading edge propellers and their relative operating speeds, inclusive of time varying effects associated with motor controller error and atmospheric turbulence, was considered. It was found that the mean annoyance response varies in a statistically significant manner with the number of propellers and with the inclusion of time varying effects, but does not differ significantly with the relative RPM between propellers. An annoyance model was developed, inclusive of confidence intervals, using the noise metrics of loudness, roughness, and tonality as predictors.

  19. Modeling of low- and high-frequency noise by slow and fast fluctuators

    Science.gov (United States)

    Nesterov, Alexander I.; Berman, Gennady P.

    2012-05-01

    We study the dynamics of dephasing in a quantum two-level system by modeling both 1/f and high-frequency noise by random telegraph processes. Our approach is based on a so-called spin-fluctuator model in which a noisy environment is modeled by a large number of fluctuators. In the continuous limit we obtain an effective random process (ERP) that is described by a distribution function of the fluctuators. In a simplified model, we reduce the ERP to the two (slow and fast) ensembles of fluctuators. Using this model, we study decoherence in a superconducting flux qubit and we compare our theoretical results with the available experimental data. We demonstrate good agreement of our theoretical predictions with the experiments. Our approach can be applied to many quantum systems, such as biological complexes, semiconductors, superconducting, and spin qubits, where the effects of interaction with the environment are essential.

  20. Microstructures and Crackling Noise of AlxNbTiMoV High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Shu Ying Chen

    2014-02-01

    Full Text Available A series of high entropy alloys (HEAs, AlxNbTiMoV, was produced by a vacuum arc-melting method. Their microstructures and compressive mechanical behavior at room temperature were investigated. It has been found that a single solid-solution phase with a body-centered cubic (BCC crystal structure forms in these alloys. Among these alloys, Al0.5NbTiMoV reaches the highest yield strength (1,625 MPa, which should be attributed to the considerable solid-solution strengthening behavior. Furthermore, serration and crackling noises near the yielding point was observed in the NbTiMoV alloy, which represents the first such reported phenomenon at room temperature in HEAs.

  1. Modeling of Low and High Frequency Noise by Slow and Fast Fluctuators

    CERN Document Server

    Nesterov, Alexander I

    2012-01-01

    We study the dynamics of dephasing in a quantum two-level system by modeling both $1/f$ and high-frequency noise by random telegraph processes. Our approach is based on a so-called spin-fluctuator model in which a noisy environment is modelled by a large number of fluctuators. In the continuous limit we obtain an effective random process (ERP) that is described by a distribution function of the fluctuators. In a simplified model, we reduce the ERP to the two (slow and fast) effective fluctuators. Using this model, we study decoherence in a superconducting flux qubit and we compare our theoretical results with the available experimental data. We demonstrate good agreement of our theoretical predictions with the experiments. Our approach can be applied to many quantum systems, such as photosynthetic complexes, semiconductors, and superconducting and spin qubits, where the effects of interaction with the environment are essential.

  2. A full-spectrum analysis of high-speed train interior noise under multi-physical-field coupling excitations

    Science.gov (United States)

    Zheng, Xu; Hao, Zhiyong; Wang, Xu; Mao, Jie

    2016-06-01

    High-speed-railway-train interior noise at low, medium, and high frequencies could be simulated by finite element analysis (FEA) or boundary element analysis (BEA), hybrid finite element analysis-statistical energy analysis (FEA-SEA) and statistical energy analysis (SEA), respectively. First, a new method named statistical acoustic energy flow (SAEF) is proposed, which can be applied to the full-spectrum HST interior noise simulation (including low, medium, and high frequencies) with only one model. In an SAEF model, the corresponding multi-physical-field coupling excitations are firstly fully considered and coupled to excite the interior noise. The interior noise attenuated by sound insulation panels of carriage is simulated through modeling the inflow acoustic energy from the exterior excitations into the interior acoustic cavities. Rigid multi-body dynamics, fast multi-pole BEA, and large-eddy simulation with indirect boundary element analysis are first employed to extract the multi-physical-field excitations, which include the wheel-rail interaction forces/secondary suspension forces, the wheel-rail rolling noise, and aerodynamic noise, respectively. All the peak values and their frequency bands of the simulated acoustic excitations are validated with those from the noise source identification test. Besides, the measured equipment noise inside equipment compartment is used as one of the excitation sources which contribute to the interior noise. Second, a full-trimmed FE carriage model is firstly constructed, and the simulated modal shapes and frequencies agree well with the measured ones, which has validated the global FE carriage model as well as the local FE models of the aluminum alloy-trim composite panel. Thus, the sound transmission loss model of any composite panel has indirectly been validated. Finally, the SAEF model of the carriage is constructed based on the accurate FE model and stimulated by the multi-physical-field excitations. The results show

  3. Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Jannis Lübbe

    2013-01-01

    Full Text Available The noise of the frequency-shift signal Δf in noncontact atomic force microscopy (NC-AFM consists of cantilever thermal noise, tip–surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density dz at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density dΔf at the demodulator output in dependence of cantilever properties and settings of the signal processing electronics in the limit of a negligible tip–surface interaction and a measurement under ultrahigh-vacuum conditions. For a quantification of the noise figures, we calibrate the cantilever displacement signal and determine the transfer function of the signal-processing electronics. From the transfer function and the measured dz, we predict dΔf for specific filter settings, a given level of detection-system noise spectral density dzds and the cantilever-thermal-noise spectral density dzth. We find an excellent agreement between the calculated and measured values for dΔf. Furthermore, we demonstrate that thermal noise in dΔf, defining the ultimate limit in NC-AFM signal detection, can be kept low by a proper choice of the cantilever whereby its Q-factor should be given most attention. A system with a low-noise signal detection and a suitable cantilever, operated with appropriate filter and feedback-loop settings allows room temperature NC-AFM measurements at a low thermal-noise limit with a significant bandwidth.

  4. Characterization of High-Power Rocket and Jet Noise Using Near-Field Acoustical Holography

    OpenAIRE

    2010-01-01

    Structural fatigue, hearing damage, and community disturbances are all consequences of rocket and jet noise, especially as they become more powerful. Noise-reduction schemes require accurate characterization of the noise sources within rocket plumes and jets. Nearfield acoustical holography (NAH) measurements were made to visualize the sound field in the jet exhaust region of an F-22 Raptor. This is one of the largest-scale applications of NAH since its development in the 1980s. A scan-based ...

  5. Visual recovery in cortical blindness is limited by high internal noise.

    Science.gov (United States)

    Cavanaugh, Matthew R; Zhang, Ruyuan; Melnick, Michael D; Das, Anasuya; Roberts, Mariel; Tadin, Duje; Carrasco, Marisa; Huxlin, Krystel R

    2015-01-01

    Damage to the primary visual cortex typically causes cortical blindness (CB) in the hemifield contralateral to the damaged hemisphere. Recent evidence indicates that visual training can partially reverse CB at trained locations. Whereas training induces near-complete recovery of coarse direction and orientation discriminations, deficits in fine motion processing remain. Here, we systematically disentangle components of the perceptual inefficiencies present in CB fields before and after coarse direction discrimination training. In seven human CB subjects, we measured threshold versus noise functions before and after coarse direction discrimination training in the blind field and at corresponding intact field locations. Threshold versus noise functions were analyzed within the framework of the linear amplifier model and the perceptual template model. Linear amplifier model analysis identified internal noise as a key factor differentiating motion processing across the tested areas, with visual training reducing internal noise in the blind field. Differences in internal noise also explained residual perceptual deficits at retrained locations. These findings were confirmed with perceptual template model analysis, which further revealed that the major residual deficits between retrained and intact field locations could be explained by differences in internal additive noise. There were no significant differences in multiplicative noise or the ability to process external noise. Together, these results highlight the critical role of altered internal noise processing in mediating training-induced visual recovery in CB fields, and may explain residual perceptual deficits relative to intact regions of the visual field.

  6. Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of an Ultra High Bypass Ratio Fan

    Science.gov (United States)

    Hughes, Christoper E.; Gazzaniga, John A.

    2013-01-01

    A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

  7. New decision-based trimmed median filter for high-density salt-and-pepper noise removal in images

    Science.gov (United States)

    Vijaykumar, Vaithiyam Rengarajan; Santhanamari, Guru

    2014-05-01

    A new switching-based trimmed median filter to remove high-density salt-and-pepper noise in digital images is proposed. Initially, a 3×3 sliding window is applied on each pixel in the noisy image. The minimum- and maximum-intensity values are trimmed, and the noisy pixels are detected based on the predefined threshold value. In the filtering stage, the noisy pixels are replaced by median value of uncorrupted pixels in the trimmed array. At very high noise density, if all the pixels in the sliding window are corrupted, then the proposed algorithm replaces noisy pixels by the midpoint of recently processed pixels. The experimental results for various test images show that the performance of the proposed algorithm is superior to the existing algorithms, namely SMF, WMF, CWMF, AMF, DBA, and MDBUTMF in terms of visual quality and edge preservation, even at noise levels as high as 95%.

  8. Combined Effects of High-Speed Railway Noise and Ground Vibrations on Annoyance.

    Science.gov (United States)

    Yokoshima, Shigenori; Morihara, Takashi; Sato, Tetsumi; Yano, Takashi

    2017-07-27

    The Shinkansen super-express railway system in Japan has greatly increased its capacity and has expanded nationwide. However, many inhabitants in areas along the railways have been disturbed by noise and ground vibration from the trains. Additionally, the Shinkansen railway emits a higher level of ground vibration than conventional railways at the same noise level. These findings imply that building vibrations affect living environments as significantly as the associated noise. Therefore, it is imperative to quantify the effects of noise and vibration exposures on each annoyance under simultaneous exposure. We performed a secondary analysis using individual datasets of exposure and community response associated with Shinkansen railway noise and vibration. The data consisted of six socio-acoustic surveys, which were conducted separately over the last 20 years in Japan. Applying a logistic regression analysis to the datasets, we confirmed the combined effects of vibration/noise exposure on noise/vibration annoyance. Moreover, we proposed a representative relationship between noise and vibration exposures, and the prevalence of each annoyance associated with the Shinkansen railway.

  9. High-frequency noise modeling of Si(Ge) bipolar transistors

    NARCIS (Netherlands)

    Vitale, F.

    2014-01-01

    The design and the optimization of electronic systems often requires a detailed knowledge of the inherent noise generated within semiconductor active devices, constituting the core of such systems. Examples of applications in which noise is a key issue include receiver front-ends in radiofrequency (

  10. Integrated covariance estimation using high-frequency data in the presence of noise

    DEFF Research Database (Denmark)

    Voev, Valeri; Lunde, Asger

    2007-01-01

    We analyze the effects of nonsynchronicity and market microstructure noise on realized covariance type estimators. Hayashi and Yoshida (2005) propose a simple estimator that resolves the problem of nonsynchronicity and is unbiased and consistent for the integrated covariance in the absence of noise...

  11. Reflection seismic imaging of a hydraulically conductive fracture zone in a high noise area, Forsmark, Sweden

    Science.gov (United States)

    Juhlin, C.; Stephens, M. B.; Cosma, C.

    2007-05-01

    High resolution reflection seismic methods have proven to be useful tools for locating fracture zones in crystalline rock. Siting of potential high-level nuclear waste repositories is a particularly important application of these methods. By using small explosive sources (15-75 grams), high resolution images of the sub-surface have been obtained in the depth range 100 m to 2 km in Sweden, Canada and elsewhere. Although ambient noise conditions in areas such as the Fennoscandian and Canadian shields are generally low, industrial noise can be high in some areas, particularly at potential sites suitable for repositories, since these are often close to existing infrastructure. In addition, the presence of this infrastructure limits the choice of sources available to the geophysicist. Forsmark, located about 140 km north of Stockholm, is one such potential site where reflection seismics have been carried out. Existing infrastructure includes nuclear reactors for power generation and a low- level waste repository. In the vicinity of the reactors, it was not possible to use an explosive source due to permitting restrictions. Instead, a VIBSIST system consisting of a tractor mounted hydraulic hammer was used in the vicinity of the reactors. By repeatedly hitting the pavement, without breaking it, at predefined sweeps and then stacking the signals, shot records comparable to explosive data could be generated. These shot records were then processed using standard methods to produce stacked sections along 3 profiles within the reactor area. Clear reflections are seen in the uppermost 600 m along 3 of these profiles. Correlation of crossing profiles shows that the strongest reflection (B8) is generated by a gently east-southeast dipping interface. Prior to construction of the reactors, several boreholes were drilled to investigate the bedrock in the area. One of these boreholes was located close to where two of the profiles cross. Projection of the B8 reflection into the

  12. Lineshape spectroscopy with a very high resolution, very high signal-to-noise crystal spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Beiersdorfer, P.; Magee, E. W.; Brown, G. V.; Chen, H.; Emig, J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte & ECAP, Universität Erlangen-Nürnberg, 96049 Bamberg (Germany); Bitter, M.; Hill, K. W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Allan, P.; Brown, C. R. D.; Hill, M. P.; Hoarty, D. J.; Hobbs, L. M. R.; James, S. F. [Directorate of Research and Applied Science, AWE plc, Reading RG7 4PR (United Kingdom)

    2016-06-15

    We have developed a high-resolution x-ray spectrometer for measuring the shapes of spectral lines produced from laser-irradiated targets on the Orion laser facility. The instrument utilizes a spherically bent crystal geometry to spatially focus and spectrally analyze photons from foil or microdot targets. The high photon collection efficiency resulting from its imaging properties allows the instrument to be mounted outside the Orion chamber, where it is far less sensitive to particles, hard x-rays, or electromagnetic pulses than instruments housed close to the target chamber center in ten-inch manipulators. Moreover, Bragg angles above 50° are possible, which provide greatly improved spectral resolution compared to radially viewing, near grazing-incidence crystal spectrometers. These properties make the new instrument an ideal lineshape diagnostic for determining plasma temperature and density. We describe its calibration on the Livermore electron beam ion trap facility and present spectral data of the K-shell emission from highly charged sulfur produced by long-pulse as well as short-pulse beams on the Orion laser in the United Kingdom.

  13. High-speed imaging, acoustic features, and aeroacoustic computations of jet noise from Strombolian (and Vulcanian) explosions

    Science.gov (United States)

    Taddeucci, J.; Sesterhenn, J.; Scarlato, P.; Stampka, K.; Del Bello, E.; Pena Fernandez, J. J.; Gaudin, D.

    2014-05-01

    High-speed imaging of explosive eruptions at Stromboli (Italy), Fuego (Guatemala), and Yasur (Vanuatu) volcanoes allowed visualization of pressure waves from seconds-long explosions. From the explosion jets, waves radiate with variable geometry, timing, and apparent direction and velocity. Both the explosion jets and their wave fields are replicated well by numerical simulations of supersonic jets impulsively released from a pressurized vessel. The scaled acoustic signal from one explosion at Stromboli displays a frequency pattern with an excellent match to those from the simulated jets. We conclude that both the observed waves and the audible sound from the explosions are jet noise, i.e., the typical acoustic field radiating from high-velocity jets. Volcanic jet noise was previously quantified only in the infrasonic emissions from large, sub-Plinian to Plinian eruptions. Our combined approach allows us to define the spatial and temporal evolution of audible jet noise from supersonic jets in small-scale volcanic eruptions.

  14. Full-scale tests of reflective noise-reducing devices for balconies on high-rise buildings.

    Science.gov (United States)

    Ishizuka, Takashi; Fujiwara, Kyoji

    2013-08-01

    In the present report, the noise-shielding efficiency of balconies with ceiling-mounted reflectors on the façades of high-rise buildings is examined through full-scale field measurements. The reflectors are designed to reflect direct and diffracted waves incident on the balcony ceiling outside the balcony. Field measurements are conducted to investigate the performance of the reflectors on intermediate floors of a high-rise dwelling adjacent to a railway. The reflectors reduce railway noise by approximately 5 dB, in A-weighted sound pressure level, compared to an ordinary balcony. The noise-shielding efficiency of a balcony equipped with reflectors is greater than that of an absorbing balcony.

  15. Statistical-noise reduction in correlation analysis of high-energy nuclear collisions with event-mixing

    CERN Document Server

    Ray, R L

    2016-01-01

    The error propagation and statistical-noise reduction method of Reid and Trainor for two-point correlation applications in high-energy collisions is extended to include particle-pair references constructed by mixing two particles from all event-pair combinations within event subsets of arbitrary size. The Reid-Trainor method is also applied to other particle-pair mixing algorithms commonly used in correlation analysis of particle production from high-energy nuclear collisions. The statistical-noise reduction, inherent in the Reid-Trainor event-mixing procedure, is shown to occur for these other event-mixing algorithms as well. Monte Carlo simulation results are presented which verify the predicted degree of noise reduction. In each case the final errors are determined by the bin-wise particle-pair number, rather than by the bin-wise single-particle count.

  16. Aerodynamic noise characterization of a full-scale wind turbine through high-frequency surface pressure measurements

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Aagaard Madsen, Helge; Bak, Christian;

    2015-01-01

    The aim of this work is to investigate and characterize the high-frequency surface pressure fluctuations on a full-scale wind turbine blade and in particular the influence of the atmospheric turbulence. As these fluctuations are highly correlated to the sources of both turbulent inflow noise...... wind turbine with a 80 m diameter rotor as well as measurements of an airfoil section tested in a wind tunnel. The turbine was extensively equipped in order to monitor the local inflow onto the rotating blades. Further a section of the 38 m long blade was instrumented with 50 microphones flush......-mounted relative to the blade surface. The measurements of surface pressure spectra are compared with the results of two engineering models for trailing edge noise and for turbulent inflow noise. The measured pressure fluctuations are related to the local inflow angle and are also compared to measurements...

  17. Statistical-noise reduction in correlation analysis of high-energy nuclear collisions with event-mixing

    Energy Technology Data Exchange (ETDEWEB)

    Ray, R.L., E-mail: ray@physics.utexas.edu; Bhattarai, P.

    2016-06-11

    The error propagation and statistical-noise reduction method of Reid and Trainor for two-point correlation applications in high-energy collisions is extended to include particle-pair references constructed by mixing two particles from all event-pair combinations within event subsets of arbitrary size. The Reid–Trainor method is also applied to other particle-pair mixing algorithms commonly used in correlation analysis of particle production from high-energy nuclear collisions. The statistical-noise reduction, inherent in the Reid–Trainor event-mixing procedure, is shown to occur for these other event-mixing algorithms as well. Monte Carlo simulation results are presented which verify the predicted degree of noise reduction. In each case the final errors are determined by the bin-wise particle-pair number, rather than by the bin-wise single-particle count.

  18. Research of reduced common-mode voltage technique with nonzero vector pulse width modulation for three-phase inverters%三相逆变器的无零矢量共模电压抑制技术研究

    Institute of Scientific and Technical Information of China (English)

    章勇高; 邝光健; 龙立中

    2013-01-01

    The common-mode suppression techniques with nonzero vector pulse width modulation (NZPWM) for three-phase inverters are studied. They are random state pulse width modulation (RSPWM), active zero state PWM1 (AZSPWM1), active zero state PWM3 (AZSPWM3) and near state PWM (NSPWM). Firstly, the operation areas of modulation factor and reference voltage vector with different modulation strategies are analyzed. The results show that RSPWM has a smaller operation area than other three NZPWM and is suitable for the application with lower modulation ratio. Secondly, the DC voltage utilization rate and output harmonic of different NZPWM are researched and compared with that of traditional space vector modulation (SVM) by using theoretical analysis and simulation. The results show that AZPWM1, AZPWM3 and NSPWM can not only suppress the common mode voltage of three-phase inverters efficiently, but also maintain high DC voltage utilization rate. However, three-phase inverters with NSPWM have the higher output harmonic comparing with the traditional SVM. The research results provide theoretical basis and instruction for the selection of common mode voltage suppression technique with NZPWM for three-phase inverters and its further study.%  研究了三相逆变器的 RSPWM、AZSPWM1、AZSPWM3和 NSPWM 无零矢量共模电压抑制技术。首先,分析了不同调制策略的调制因数和参考电压矢量的工作区间,说明了 RSPWM 的工作区间较小,适用于低调制比工作场合。再次,利用理论分析和仿真方法,研究了无零矢量调制策略的直流电压利用率和输出谐波特性,并与传统 SVM 调制策略比较。结果表明,AZSPWM1、AZSPWM3和 NSPWM 调制策略能够有效地抑制三相逆变器共模电压,同时保持了较高的直流电压利用率。但相对 SVM 调制策略,三相逆变器的输出谐波含量有所增大。研究结果为三相逆变器的无零矢量共模电压抑制技术的选用及进一步研究提供了理论依据和指导。

  19. High power and ultra-low-noise photodetector for squeezed-light enhanced gravitational wave detectors.

    Science.gov (United States)

    Grote, Hartmut; Weinert, Michael; Adhikari, Rana X; Affeldt, Christoph; Kringel, Volker; Leong, Jonathan; Lough, James; Lück, Harald; Schreiber, Emil; Strain, Kenneth A; Vahlbruch, Henning; Wittel, Holger

    2016-09-05

    Current laser-interferometric gravitational wave detectors employ a self-homodyne readout scheme where a comparatively large light power (5-50 mW) is detected per photosensitive element. For best sensitivity to gravitational waves, signal levels as low as the quantum shot noise have to be measured as accurately as possible. The electronic noise of the detection circuit can produce a relevant limit to this accuracy, in particular when squeezed states of light are used to reduce the quantum noise. We present a new electronic circuit design reducing the electronic noise of the photodetection circuit in the audio band. In the application of this circuit at the gravitational-wave detector GEO 600 the shot-noise to electronic noise ratio was permanently improved by a factor of more than 4 above 1 kHz, while the dynamic range was improved by a factor of 7. The noise equivalent photocurrent of the implemented photodetector and circuit is about 5μA/Hz above 1 kHz with a maximum detectable photocurrent of 20 mA. With the new circuit, the observed squeezing level in GEO 600 increased by 0.2 dB. The new circuit also creates headroom for higher laser power and more squeezing to be observed in the future in GEO 600 and is applicable to other optics experiments.

  20. Instrumentation for high accuracy noise characterisation of front-end devices in detector applications

    Energy Technology Data Exchange (ETDEWEB)

    Re, V. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy); Svelto, F. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy)

    1995-11-01

    The paper describes the instrumentation that was developed for the noise characterisation of field-effect and bipolar transistors. Very accurate measurements of the series noise spectral density in the frequency range 100mHz-100MHz and of the equivalent noise charge at processing times ranging from 10ns to 10{mu}s are made possible. A review of results on various device types shows how these data are used in view of applications to a broad range of experimental conditions in elementary particle and nuclear physics. (orig.).

  1. Integrated covariance estimation using high-frequency data in the presence of noise

    DEFF Research Database (Denmark)

    Voev, Valeri; Lunde, Asger

    2007-01-01

    . When noise is present, however, we find that this estimator is biased, and show how the bias can be corrected for. Ultimately, we propose a subsampling version of the bias-corrected estimator which improves its efficiency. Empirically, we find that the usual assumption of a martingale price process...... plus an independently and identically distributed (i.i.d.) noise does not describe the dynamics of the observed price process across stocks, which confirms the practical relevance of our general noise specification and the estimation techniques we propose.Finally, a simulation experiment is carried out...

  2. Design of a high performance low aerodynamic noise axial flow fan

    OpenAIRE

    2007-01-01

    The project starts with a description of the main sources of noise in an axial flow fan for concluding that the thing we should avoid is the trailing edge noise. After that the formulas for designing a fan and an aerodynamics background are presented. Once we get the results of these formulas a low noise optimization is carried on for leading us to a table of results where the main characteristics of design for our fan are obtained. After these tables the design of the fan is obtained with Pr...

  3. Dynamics of Bloch oscillating transistor near bifurcation threshold and its applicability for common mode rejection capability of a differential pair BOT

    Science.gov (United States)

    Sarkar, Jayanta; Puska, Antti; Hassel, Juha; Hakonen, Pertti

    2014-03-01

    Bloch oscillating transistor (BOT) is mesoscopic current amplier based on a combination of a Josephson junction or a squid connected with a large resistor and a NIS junction. We have studied the dynamics of BOT near the bifurcation threshold. This is an important feature for an amplifier as this can be utilized to improve its performance characteristics. We have measured the I - V characteristics of the BOT with different base currents (IB) over a wide range of Josephson coupling energies (EJ) . The current gain (β) is found to be increasing with increasing IB and eventually diverging. We have found a record large β = 50 in our experiment. In order to determine the common mode rejection ratio (CMRR) of a differential pair BOT we have used two BOTs fabricated on the same chip. The common mode port is connected to the bases of the two BOTs and fed with varying voltages; simultaneously emitter currents of the two BOTs are recorded. In our experiment we found a 20dB of CMRR.

  4. Turbulent-PSO-Based Fuzzy Image Filter With No-Reference Measures for High-Density Impulse Noise.

    Science.gov (United States)

    Chou, Hsien-Hsin; Hsu, Ling-Yuan; Hu, Hwai-Tsu

    2013-02-01

    Digital images are often corrupted by impulsive noise during data acquisition, transmission, and processing. This paper presents a turbulent particle swarm optimization (PSO) (TPSO)-based fuzzy filtering (or TPFF for short) approach to remove impulse noise from highly corrupted images. The proposed fuzzy filter contains a parallel fuzzy inference mechanism, a fuzzy mean process, and a fuzzy composition process. To a certain extent, the TPFF is an improved and online version of those genetic-based algorithms which had attracted a number of works during the past years. As the PSO is renowned for its ability of achieving success rate and solution quality, the superiority of the TPFF is almost for sure. In particular, by using a no-reference Q metric, the TPSO learning is sufficient to optimize the parameters necessitated by the TPFF. Therefore, the proposed fuzzy filter can cope with practical situations where the assumption of the existence of the "ground-truth" reference does not hold. The experimental results confirm that the TPFF attains an excellent quality of restored images in terms of peak signal-to-noise ratio, mean square error, and mean absolute error even when the noise rate is above 0.5 and without the aid of noise-free images.

  5. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock.

    Science.gov (United States)

    François, B; Calosso, C E; Danet, J M; Boudot, R

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad(2)/Hz and -129 dB rad(2)/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10(-14) at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  6. A 6 GHz high power and low phase noise VCO using an InGaP/GaAs HBT

    Institute of Scientific and Technical Information of China (English)

    王显泰; 申华军; 金智; 陈延湖; 刘新宇

    2009-01-01

    A 6 GHz voltage controlled oscillator (VCO) optimized for power and noise performance was designed and characterized. This VCO was designed with the negative-resistance (Neg-R) method, utilizing an InGaP/GaAs hetero-junction bipolar transistor in the negative-resistance block. A proper output matching network and a high Q stripe line resonator were used to enhance output power and depress phase noise. Measured central frequency of the VCO was 6.008 GHz. The tuning range was more than 200 MHz. At the central frequency, an output power of 9.8 dBm and phase noise of -122.33 dBc/Hz at 1 MHz offset were achieved, the calculated RF to DC efficiency was about 14%, and the figure of merit was -179.2 dBc/Hz.

  7. High accuracy measurement of low-frequency noise in front-end p-channel FETs

    Energy Technology Data Exchange (ETDEWEB)

    Re, V. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy); Svelto, F. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy)

    1995-11-01

    The paper describes the instrumentation that was developed to allow series noise spectral analysis on field effect transistors. Analog interfaces between the device under test and commercial available analysers, working in the frequency range 100mHz-100kHz, have been designed and realised. The intrinsic noise contribution of the interface is estimated to be 1nV/{radical}(Hz) at 100mHz and 50pV/{radical}(Hz) beyond 1kHz. The basic idea is to amplify the noise of the device under test through a capacitive feedback loop, which is theoretically noiseless. The paper is focused on the design and the performances of the interface for the noise characterisation of p-channel FETs. (orig.).

  8. A High Performance Approach to Local Active Noise Reduction in Noisy Cabins Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft cabin is noisy and uncomfortable. Sometimes, the noise level can exceed 80 dBA. There are 2 challenges to meet the above needs. One is to generate an...

  9. Unstructured, High-Order Scheme Module with Low Dissipation Flux Difference Splitting for Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorough understanding of aircraft airframe and engine noise mechanisms and the subsequent acoustic propagation to the farfield is necessary to develop and evaluate...

  10. Non-Linear Noise Contributions in Highly Dispersive Optical Transmission Systems

    Science.gov (United States)

    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.

  11. High Sensitivity Pulsed Laser Vibrometer for Aircraft Interior Noise Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an innovative pulsed laser vibrometer technology for the monitoring of interior noise inside an aircraft. The optical speckle-tolerant nature of the...

  12. Spectral characteristics of high-latitude raw 40 MHz cosmic noise signals

    Science.gov (United States)

    Hall, Chris M.

    2016-08-01

    Cosmic noise at 40 MHz is measured at Ny-Ålesund (79° N, 12° E) using a relative ionospheric opacity meter ("riometer"). A riometer is normally used to determine the degree to which cosmic noise is absorbed by the intervening ionosphere, giving an indication of ionisation of the atmosphere at altitudes lower than generally monitored by other instruments. The usual course is to determine a "quiet-day" variation, this representing the galactic noise signal itself in the absence of absorption; the current signal is then subtracted from this to arrive at absorption expressed in decibels (dB). By a variety of means and assumptions, it is thereafter possible to estimate electron density profiles in the very lowest reaches of the ionosphere. Here however, the entire signal, i.e. including the cosmic noise itself, will be examined and spectral characteristics identified. It will be seen that distinct spectral subranges are evident which can, in turn, be identified with non-Gaussian processes characterised by generalised Hurst exponents, α. Considering all periods greater than 1 h, α ≈ 24, an indication of fractional Brownian motion, whereas for periods greater than 1 day α ≈ 0.9 - approximately pink noise and just in the domain of fractional Gaussian noise. The results are compared with other physical processes, suggesting that absorption of cosmic noise is characterised by a generalised Hurst exponent ≈ 1.24 and thus non-persistent fractional Brownian motion, whereas generation of cosmic noise is characterised by a generalised Hurst exponent ≈ 1. The technique unfortunately did not result in clear physical understanding of the ionospheric phenomena, and thus, in this respect, the application was not successful; the analysis could, however, be used as a tool for instrument validation.

  13. Numerical prediction of flow induced noise in free jets of high Mach numbers

    OpenAIRE

    Schönrock, Olaf

    2009-01-01

    A direct aeroacoustic simulation methodology is developed on the basis of the numerical schemes implemented in the commercial tool ANSYS CFX. The focus lies upon the efficient and direct numerical prediction of the flow-induced noise generated by natural gas and pneumatic applications. The respective compressed gas related components are characterized by tiny supersonic gas jets, strong noise emissions, poor accessibility by measurement techniques and excessive simulation costs in particular...

  14. Computationally efficient algorithm for high sampling-frequency operation of active noise control

    Science.gov (United States)

    Rout, Nirmal Kumar; Das, Debi Prasad; Panda, Ganapati

    2015-05-01

    In high sampling-frequency operation of active noise control (ANC) system the length of the secondary path estimate and the ANC filter are very long. This increases the computational complexity of the conventional filtered-x least mean square (FXLMS) algorithm. To reduce the computational complexity of long order ANC system using FXLMS algorithm, frequency domain block ANC algorithms have been proposed in past. These full block frequency domain ANC algorithms are associated with some disadvantages such as large block delay, quantization error due to computation of large size transforms and implementation difficulties in existing low-end DSP hardware. To overcome these shortcomings, the partitioned block ANC algorithm is newly proposed where the long length filters in ANC are divided into a number of equal partitions and suitably assembled to perform the FXLMS algorithm in the frequency domain. The complexity of this proposed frequency domain partitioned block FXLMS (FPBFXLMS) algorithm is quite reduced compared to the conventional FXLMS algorithm. It is further reduced by merging one fast Fourier transform (FFT)-inverse fast Fourier transform (IFFT) combination to derive the reduced structure FPBFXLMS (RFPBFXLMS) algorithm. Computational complexity analysis for different orders of filter and partition size are presented. Systematic computer simulations are carried out for both the proposed partitioned block ANC algorithms to show its accuracy compared to the time domain FXLMS algorithm.

  15. High Spatial Density Ambient Noise Tomography at the El Jefe Geyser, Chile

    Science.gov (United States)

    Hakso, A. W.; Seats, K.

    2015-12-01

    The El Jefe geyser in the Atacama Desert, Chile has been the subject of study to better understand processes of heat transport and eruption mechanisms in geyser systems (Munoz-Saez et al., 2015). Existing seismological literature on geyser and volcanic systems is predominantly focused on seismicity generated in the eruptive process (Benoit and McNutt, 1997; O'Brien et al., 2011). In contrast, this study leverages seismic noise in the repose period to generate an approximation to the Green's function for each receiver pair, known as noise correlation functions (NCFs). A dense seismic array of 51 geophones spaced at 2-10 meter intervals recorded several days of data at a spatial scale and frequency range approximately two orders of magnitude removed from prior seismic interferometry studies. While eruptions of the El Jefe geyser impose a transient signal on a diffuse background noise, a regular eruption interval of 132.52.5 seconds (Munoz-Saez et al., 2015) allows for reliable removal of seismic energy associated with the eruption, improving the azimuthal distribution of noise across the array. The approach to generating noise correlation functions closely follows the methodology of Seats and Lawrence (2014). Moveout of at least two phases of energy is apparent in the calculated NCFs, suggesting that multiple phases of seismic energy may be present in the noise, moving coherently across the array.

  16. Hybrid CFD/FEM-BEM simulation of cabin aerodynamic noise for vehicles traveling at high speed

    Institute of Scientific and Technical Information of China (English)

    WANG; YiPing; ZHEN; Xin; WU; Jing; GU; ZhengQi; XIAO; ZhenYi; YANG; Xue

    2013-01-01

    Flow passing a vehicle may lead to the increase of the cabin interior noise level through a variety of mechanisms. These mechanisms include vibrations caused by aerodynamic excitations and reradiation from the glass panels, exterior noise trans-mitted and leaked through door seals including gaps and glass edge, and transmission of airborne noise generated by the interaction of flow with body panels. It is of vital importance to predict both the flow fields and the acoustic sources around the ve-hicle to accurately assess the impact of wind induced noise inside the cabin. In the present study, an unstructured segregated finite volume model was used to calculate the flow fields in which a hexahedron grid is used to simplify the vehicle geometry.A large eddy simulation coupled with a wall function model was applied to predict the exterior transient flow fields. The mean flow quantities were thus calculated along the symmetry plane and the vehicle’s side windows. A coupled FEM/BEM method was used to compute the vehicle’s interior noise level. The total contribution of the interior noise level due to the body panels of the vehicle was subsequently analyzed.

  17. Jet-Surface Interaction Noise from High-Aspect Ratio Nozzles: Test Summary

    Science.gov (United States)

    Brown, Clifford; Podboy, Gary

    2017-01-01

    Noise and flow data have been acquired for a 16:1 aspect ratio rectangular nozzle exhausting near a simple surface at the NASA Glenn Research Center as part of an ongoing effort to understand, model, and predict the noise produced by current and future concept aircraft employing a tightly integrated engine airframe designs. The particular concept under consideration in this experiment is a blended-wing-body airframe powered by a series of electric fans exhausting through slot nozzle over an aft deck. The exhaust Mach number and surface length were parametrically varied during the test. Far-field noise data were acquired for all nozzle surface geometries and exhaust flow conditions. Phased-array noise source localization data and in-flow pressure data were also acquired for a subset of the isolated (no surface) and surface configurations; these measurements provide data that have proven useful for modeling the jet-surface interaction noise source and the surface effect on the jet-mixing noise in round jets. A summary of the nozzle surface geometry, flow conditions tested, and data collected are presented.

  18. Large Eddy Simulation of Airfoil Self-Noise at High Reynolds Number

    Science.gov (United States)

    Kocheemoolayil, Joseph; Lele, Sanjiva

    2015-11-01

    The trailing edge noise section (Category 1) of the Benchmark Problems for Airframe Noise Computations (BANC) workshop features five canonical problems. No first-principles based approach free of empiricism and tunable coefficients has successfully predicted trailing edge noise for the five configurations to date. Our simulations predict trailing edge noise accurately for all five configurations. The simulation database is described in detail, highlighting efforts undertaken to validate the results through systematic comparison with dedicated experiments and establish insensitivity to grid resolution, domain size, alleatory uncertainties such as the tripping mechanism used to force transition to turbulence and epistemic uncertainties such as models for unresolved near-wall turbulence. Ongoing efforts to extend the predictive capability to non-canonical configurations featuring flow separation are summarized. A novel, large-span calculation that predicts the flow past a wind turbine airfoil in deep stall with unprecedented accuracy is presented. The simulations predict airfoil noise in the near-stall regime accurately. While the post-stall noise predictions leave room for improvement, significant uncertainties in the experiment might preclude a fair comparison in this regime. We thank Cascade Technologies Inc. for providing access to the CharLES toolkit - a massively-parallel, unstructured large eddy simulation framework.

  19. Inhibition of voltage-gated calcium channels as common mode of action for (mixtures of) distinct classes of insecticides.

    Science.gov (United States)

    Meijer, Marieke; Dingemans, Milou M L; van den Berg, Martin; Westerink, Remco H S

    2014-09-01

    Humans are exposed to distinct structural classes of insecticides with different neurotoxic modes of action. Because calcium homeostasis is essential for proper neuronal function and development, we investigated the effects of insecticides from different classes (pyrethroid: (α-)cypermethrin; organophosphate: chlorpyrifos; organochlorine: endosulfan; neonicotinoid: imidacloprid) and mixtures thereof on the intracellular calcium concentration ([Ca(2+)]i). Effects of acute (20 min) exposure to (mixtures of) insecticides on basal and depolarization-evoked [Ca(2+)]i were studied in vitro with Fura-2-loaded PC12 cells and high resolution single-cell fluorescence microscopy. The data demonstrate that cypermethrin, α-cypermethrin, endosulfan, and chlorpyrifos concentration-dependently decreased depolarization-evoked [Ca(2+)]i, with 50% (IC50) at 78nM, 239nM, 250nM, and 899nM, respectively. Additionally, acute exposure to chlorpyrifos or endosulfan (10μM) induced a modest increase in basal [Ca(2+)]i, amounting to 68 ± 8nM and 53 ± 8nM, respectively. Imidacloprid did not disturb basal or depolarization-evoked [Ca(2+)]i at 10μM. Following exposure to binary mixtures, effects on depolarization-evoked [Ca(2+)]i were within the expected effect additivity range, whereas the effect of the tertiary mixture was less than this expected additivity effect range. These results demonstrate that different types of insecticides inhibit depolarization-evoked [Ca(2+)]i in PC12 cells by inhibiting voltage-gated calcium channels (VGCCs) in vitro at concentrations comparable with human occupational exposure levels. Moreover, the effective concentrations in this study are below those for earlier described modes of action. Because inhibition of VGCCs appears to be a common and potentially additive mode of action of several classes of insecticides, this target should be considered in neurotoxicity risk assessment studies. © The Author 2014. Published by Oxford University Press on behalf

  20. High-Resolution Dual-Comb Spectroscopy with Ultra-Low Noise Frequency Combs

    Science.gov (United States)

    Hänsel, Wolfgang; Giunta, Michele; Beha, Katja; Perry, Adam J.; Holzwarth, R.

    2017-06-01

    Dual-comb spectroscopy is a powerful tool for fast broad-band spectroscopy due to the parallel interrogation of thousands of spectral lines. Here we report on the spectroscopic analysis of acetylene vapor in a pressurized gas cell using two ultra-low noise frequency combs with a repetition rate around 250 MHz. Optical referencing to a high-finesse cavity yields a sub-Hertz stability of all individual comb lines (including the virtual comb lines between 0 Hz and the carrier) and permits one to pick a small difference of repetition rate for the two frequency combs on the order of 300 Hz, thus representing an optical spectrum of 100 THz (˜3300 \\wn) within half the free spectral range (125 MHz). The transmission signal is derived straight from a photodetector and recorded with a high-resolution spectrum analyzer or digitized with a computer-controlled AD converter. The figure to the right shows a schematic of the experimental setup which is all fiber-coupled with polarization-maintaining fiber except for the spectroscopic cell. The graph on the lower right reveals a portion of the recorded radio-frequency spectrum which has been scaled to the optical domain. The location of the measured absorption coincides well with data taken from the HITRAN data base. Due to the intrinsic linewidth of all contributing comb lines, each sampling point in the transmission graph corresponds to the probing at an optical frequency with sub-Hertz resolution. This resolution is maintained in coherent wavelength conversion processes such as difference-frequency generation (DFG), sum-frequency generation (SFG) or non-linear broadening (self-phase modulation), and is therefore easily transferred to a wide spectral range from the mid infrared up to the visible spectrum.

  1. SVPWM Technique with Varying DC-Link Voltage for Common Mode Voltage Reduction in a Matrix Converter and Analytical Estimation of its Output Voltage Distortion

    Science.gov (United States)

    Padhee, Varsha

    Common Mode Voltage (CMV) in any power converter has been the major contributor to premature motor failures, bearing deterioration, shaft voltage build up and electromagnetic interference. Intelligent control methods like Space Vector Pulse Width Modulation (SVPWM) techniques provide immense potential and flexibility to reduce CMV, thereby targeting all the afore mentioned problems. Other solutions like passive filters, shielded cables and EMI filters add to the volume and cost metrics of the entire system. Smart SVPWM techniques therefore, come with a very important advantage of being an economical solution. This thesis discusses a modified space vector technique applied to an Indirect Matrix Converter (IMC) which results in the reduction of common mode voltages and other advanced features. The conventional indirect space vector pulse-width modulation (SVPWM) method of controlling matrix converters involves the usage of two adjacent active vectors and one zero vector for both rectifying and inverting stages of the converter. By suitable selection of space vectors, the rectifying stage of the matrix converter can generate different levels of virtual DC-link voltage. This capability can be exploited for operation of the converter in different ranges of modulation indices for varying machine speeds. This results in lower common mode voltage and improves the harmonic spectrum of the output voltage, without increasing the number of switching transitions as compared to conventional modulation. To summarize it can be said that the responsibility of formulating output voltages with a particular magnitude and frequency has been transferred solely to the rectifying stage of the IMC. Estimation of degree of distortion in the three phase output voltage is another facet discussed in this thesis. An understanding of the SVPWM technique and the switching sequence of the space vectors in detail gives the potential to estimate the RMS value of the switched output voltage of any

  2. Lip-reading aids word recognition most in moderate noise: a Bayesian explanation using high-dimensional feature space.

    Directory of Open Access Journals (Sweden)

    Wei Ji Ma

    Full Text Available Watching a speaker's facial movements can dramatically enhance our ability to comprehend words, especially in noisy environments. From a general doctrine of combining information from different sensory modalities (the principle of inverse effectiveness, one would expect that the visual signals would be most effective at the highest levels of auditory noise. In contrast, we find, in accord with a recent paper, that visual information improves performance more at intermediate levels of auditory noise than at the highest levels, and we show that a novel visual stimulus containing only temporal information does the same. We present a Bayesian model of optimal cue integration that can explain these conflicts. In this model, words are regarded as points in a multidimensional space and word recognition is a probabilistic inference process. When the dimensionality of the feature space is low, the Bayesian model predicts inverse effectiveness; when the dimensionality is high, the enhancement is maximal at intermediate auditory noise levels. When the auditory and visual stimuli differ slightly in high noise, the model makes a counterintuitive prediction: as sound quality increases, the proportion of reported words corresponding to the visual stimulus should first increase and then decrease. We confirm this prediction in a behavioral experiment. We conclude that auditory-visual speech perception obeys the same notion of optimality previously observed only for simple multisensory stimuli.

  3. Extracting Near-Field Structures Related to Noise Production in High Speed Jet

    Science.gov (United States)

    Kan, Pinqing; Lewalle, Jacques; Syracuse University Team

    2015-11-01

    Jet noise research started with Lighthill's seminal work on aerodynamic sound in 1952. The current consensus is that jet noise has two main kinds of sources, the large turbulent structures and the fine-scale turbulence. Coherent structures and the noise they produce are the focus of this paper because they offer better odds for control and they are associated with the most energetic part of the acoustic spectrum. We develop an algorithm using cross-correlation, continuous wavelet and pattern recognition techniques to search for near-field (NF) structures associated with far-field (FF) acoustic noise at aft angles. An experimental data is analyzed which measured a cold circular jet of Mach 0.6 (Low et al. 2013). The events identified are short wave packets in the time-frequency domain, distorted by ambient perturbations. The statistics of the event properties, including intermittency, frequency and magnitude are consistent with observations from other researchers. We investigate the localization and time sequencing of the events and use ensemble average to bring out the distinct structures associated to noise production. The filtered signals including / excluding the events are compared and the results are further tested using synthetic and randomized signals. This work has been funded by Spectral Energies LLC through an Air Force Research Lab SBIR, an AFOSR Grant and Syracuse University.

  4. High Resolution Flicker-Noise-Free Frequency Measurements of Weak Microwave Signals

    CERN Document Server

    Creedon, Daniel L; Ivanov, Eugene N; Hartnett, John G

    2011-01-01

    Amplification is usually necessary when measuring the frequency instability of microwave signals. In this work, we develop a flicker noise free frequency measurement system based on a common or shared amplifier. First, we show that correlated flicker phase noise can be cancelled in such a system. Then we compare the new system with the conventional by simultaneously measuring the beat frequency from two cryogenic sapphire oscillators with parts in 10^15 fractional frequency instability. We determine for low power, below -80 dBm, the measurements were not limited by correlated noise processes but by thermal noise of the readout amplifier. In this regime, we show that the new readout system performs as expected and at the same level as the standard system but with only half the number of amplifiers. We also show that, using a standard readout system, the next generation of cryogenic sapphire oscillators could be flicker phase noise limited when instability reaches parts in 10^16 or better

  5. Nonlinear modeling of low-to-high-frequency noise up-conversion in microwave electron devices

    Science.gov (United States)

    Filicori, Fabio; Traverso, Pier A.; Florian, Corrado

    2003-05-01

    Measurement-based, circuit-oriented non-linear noise modeling of microwave electron devices is still an open field of research, since existing approaches are not always suitable for the accurate prediction of low-frequency noise up-conversion to RF, which represents an essential information for the non-linear circuit analyses performed in the CAD of low phase-noise oscillators. In this paper a technology-independent, empirical approach to the modeling of noise contributions at the ports of electron devices, operating under strongly non-linear conditions, is proposed. Details concerning the analytical formulation of the model, which is derived by considering randomly time-varying perturbations in the basic equations of an otherwise conventional charge-controlled non-linear model, are presented, along with a discussion about the measurement techniques devoted to its experimental characterization. An example of application of the proposed Charge-Controlled Non-linear Noise (CCNN) model is considered in the case of a HBT transistor. Techniques devoted to the implementation of the obtained model in the framework of commercial CAD tools for circuit analysis and design are provided as well.

  6. Animation of natural scene by virtual eye-movements evokes high precision and low noise in V1 neurons.

    Science.gov (United States)

    Baudot, Pierre; Levy, Manuel; Marre, Olivier; Monier, Cyril; Pananceau, Marc; Frégnac, Yves

    2013-01-01

    Synaptic noise is thought to be a limiting factor for computational efficiency in the brain. In visual cortex (V1), ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating) or higher dimensionality statistics (dense noise). In most cells, natural scene animation was the only condition where high temporal precision (in the 10-20 ms range) was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms) "spike-less" periods. We showed that both the spatial structure of natural scenes and the temporal dynamics of eye-movements increase the signal-to-noise ratio by a non-linear amplification of the signal combined with a reduction of the subthreshold contextual noise. These data support the view that the sparsening and the time precision of the neural code in V1 may depend primarily on three factors: (1) broadband input spectrum: the bandwidth must be rich enough for recruiting optimally the diversity of spatial and time constants during recurrent processing; (2) tight temporal interplay of excitation and inhibition: conductance measurements demonstrate that natural scene statistics narrow selectively the duration of the spiking opportunity window during which the balance between excitation and inhibition changes transiently and reversibly; (3) signal energy in the lower frequency band: a minimal level of power is needed below 10 Hz to reach consistently the spiking threshold, a situation rarely reached with visual dense

  7. Animation of natural scene by virtual eye-movements evokes high precision and low noise in V1 neurons

    Directory of Open Access Journals (Sweden)

    Pierre eBaudot

    2013-12-01

    Full Text Available Synaptic Noise is thought to be a limiting factor for computational efficiency in the Brain. In visual cortex (V1, ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating or higher dimensionality statistics (dense noise. In most cells, natural scene animation was the only condition where high temporal precision (in the 10-20 ms range was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms spike-less periods. We showed that both the spatial structure of natural scenes and the temporal dynamics of eye-movements increase the signal-to-noise ratio by a non linear amplification of the signal combined with a reduction of the subthreshold contextual noise. These data support the view that the sparsening and the time precision of the neural code in V1 may depend primarily on three factors: 1 broadband input spectrum: the bandwidth must be rich enough for recruiting optimally the diversity of spatial and time constants during recurrent processing; 2 tight temporal interplay of excitation and inhibition: conductance measurements demonstrate that natural scene statistics narrow selectively the duration of the spiking opportunity window during which the balance between excitation and inhibition changes transiently and reversibly; 3 signal energy in the lower frequency band: a minimal level of power is needed below 10 Hz to reach consistently the spiking threshold, a situation rarely reached with visual

  8. Sources of high frequency seismic noise: insights from a dense network of ~250 stations in northern Alsace (France)

    Science.gov (United States)

    Vergne, Jerome; Blachet, Antoine; Lehujeur, Maximilien

    2015-04-01

    Monitoring local or regional seismic activity requires stations having a low level of background seismic noise at frequencies higher than few tenths of Hertz. Network operators are well aware that the seismic quality of a site depends on several aspects, among them its geological setting and the proximity of roads, railways, industries or trees. Often, the impact of each noise source is only qualitatively known which precludes estimating the quality of potential future sites before they are tested or installed. Here, we want to take advantage of a very dense temporary network deployed in Northern Alsace (France) to assess the effect of various kinds of potential sources on the level of seismic noise observed in the frequency range 0.2-50 Hz. In September 2014, more than 250 seismic stations (FairfieldNodal@ Zland nodes with 10Hz vertical geophone) have been installed every 1.5 km over a ~25km diameter disc centred on the deep geothermal sites of Soultz-sous-Forêts and Rittershoffen. This region exhibits variable degrees of human imprints from quite remote areas to sectors with high traffic roads and big villages. It also encompasses both the deep sedimentary basin of the Rhine graben and the piedmont of the Vosges massif with exposed bedrock. For each site we processed the continuous data to estimate probability density functions of the power spectral densities. At frequencies higher than 1 Hz most sites show a clear temporal modulation of seismic noise related to human activity with the well-known variations between day and night and between weekdays and weekends. Moreover we observe a clear evolution of the spatial distribution of seismic noise levels with frequency. Basically, between 0.5 and 4 Hz the geological setting modulates the level of seismic noise. At higher frequencies, the amplitude of seismic noise appears mostly related to the distance to nearby roads. Based on road maps and traffic estimation, a forward approach is performed to model the induced

  9. The prediction of noise and installation effects of high-subsonic dual-stream jets in flight

    Science.gov (United States)

    Saxena, Swati

    Both military and civil aircraft in service generate high levels of noise. One of the major contributors to this noise generated from the aircraft is the jet engine exhaust. This makes the study of jet noise and methods to reduce jet noise an active research area with the aim of designing quieter military and commercial aircraft. The current stringent aircraft noise regulations imposed by the Federal Aviation Administration (FAA) and other international agencies, have further raised the need to perform accurate jet noise calculations for more reliable estimation of the jet noise sources. The main aim of the present research is to perform jet noise simulations of single and dual-stream jets with engineering accuracy and assess forward flight effects on the jet noise. Installation effects such as caused by the pylon are also studied using a simplified pylon nozzle configuration. Due to advances in computational power, it has become possible to perform turbulent flow simulations of high speed jets, which leads to more accurate noise predictions. In the present research, a hybrid unsteady RANS-LES parallel multi-block structured grid solver called EAGLEJet is written to perform the nozzle flow calculations. The far-field noise calculation is performed using solutions to the Ffowcs Williams and Hawkings equation. The present calculations use meshes with 5 to 11 million grid points and require about three weeks of computing time with about 100 processors. A baseline single stream convergent nozzle and a dual-stream coaxial convergent nozzle are used for the flow and noise analysis. Calculations for the convergent nozzle are performed at a high subsonic jet Mach number of Mj = 0.9, which is similar to the operating conditions for commercial aircraft engines. A parallel flow gives the flight effect, which is simulated with a co-flow Mach number, Mcf varying from 0.0 to 0.28. The grid resolution effects, statistical properties of the turbulence and the heated jet effects

  10. Modelling and measurement of high switching frequency conducted EMI

    CSIR Research Space (South Africa)

    Grobler, Inus

    2013-11-01

    Full Text Available to perform the analyses of the model, presented as a very easy and reliable tool. The common mode effect of electrically non-conductive polymer heatsinks was presented and tested as a remedy to reduce the increased common mode noise levels due to higher...

  11. Nighttime aircraft noise impairs endothelial function and increases blood pressure in patients with or at high risk for coronary artery disease.

    Science.gov (United States)

    Schmidt, Frank; Kolle, Kristoffer; Kreuder, Katharina; Schnorbus, Boris; Wild, Philip; Hechtner, Marlene; Binder, Harald; Gori, Tommaso; Münzel, Thomas

    2015-01-01

    Epidemiological studies suggest the existence of a relationship between aircraft noise exposure and increased risk for myocardial infarction and stroke. Patients with established coronary artery disease and endothelial dysfunction are known to have more future cardiovascular events. We therefore tested the effects of nocturnal aircraft noise on endothelial function in patients with or at high risk for coronary artery disease. 60 Patients (50p 1-3 vessels disease; 10p with a high Framingham Score of 23%) were exposed in random and blinded order to aircraft noise and no noise conditions. Noise was simulated in the patients' bedroom and consisted of 60 events during one night. Polygraphy was recorded during study nights, endothelial function (flow-mediated dilation of the brachial artery), questionnaires and blood sampling were performed on the morning after each study night. The mean sound pressure levels L eq(3) measured were 46.9 ± 2.0 dB(A) in the Noise 60 nights and 39.2 ± 3.1 dB(A) in the control nights. Subjective sleep quality was markedly reduced by noise from 5.8 ± 2.0 to 3.7 ± 2.2 (p aircraft noise markedly impairs endothelial function in patients with or at risk for cardiovascular disease. These vascular effects appear to be independent from annoyance and attitude towards noise and may explain in part the cardiovascular side effects of nighttime aircraft noise.

  12. Double-pass ytterbium-doped fiber amplifier with high gain coefficient and low noise figure

    Institute of Scientific and Technical Information of China (English)

    Anting Wang(王安廷); Meishu Xing(邢美术); Guanghui Chen(陈光辉); Wenkui Yang(杨文奎); Hai Ming(明海); Jianping Xie(谢建平); Yunxia Wu(吴云霞)

    2003-01-01

    We have proposed and demonstrated a double-pass ytterbium-doped fiber amplifier using an optical circulator and a fiber Bragg grating as reflector. When the signal has passed through the ytterbium-doped fiber once, it reflects off a 0.2-nm passive fiber Bragg grating filter. This reduces amplified spontaneous emission (ASE) noise from the first pass. The input signal light is amplified both forward and backward through ytterbium-doped fiber. With this double-pass configuration, 1053.15-nm unsaturated signal gain of 28 dB, gain coefficient of 1.1 dB/mW, and noise figure of less than 4 dB are achieved at 977-nm pump power of 68 mW. It is also found that this double-pass configure provides enhancing gain coefficient and improving noise figure by comparison with single-pass configuration.

  13. A Modified Decision Based Mean Median Algorithm for Removal of High Density Salt and Pepper Noise

    Directory of Open Access Journals (Sweden)

    Jitender Kumar

    2014-03-01

    Full Text Available This paper presents a modified decision based mean median filter for removal of salt and pepper noise in gray scale images. This is a computationally efficient filtering technique. It is implemented in two steps: In the first step, noisy pixels are identified and in the second step, the proposed algorithm is applied only on noisy pixels. The noise free pixels are not modified, which helps in retaining the image features. Experimental results show that the proposed algorithm performs better than various recent denoising methods in terms of PSNR, IEF and MSE.

  14. System test and noise performance studies at the ATLAS pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Weingarten, J.

    2007-09-15

    The central component of the ATLAS Inner Tracker is the pixel detector. It consists of three barrel layers and three disk-layers in the end-caps in both forward directions. The innermost barrel layer is mounted at a distance of about 5 cm from the interaction region. With its very high granularity, truly two-dimensional hit information, and fast readout it is well suited to cope with the high densities of charged tracks, expected this close to the interaction region. The huge number of readout channels necessitates a very complex services infrastructure for powering, readout and safety. After a description of the pixel detector and its services infrastructure, key results from the system test at CERN are presented. Furthermore the noise performance of the pixel detector, crucial for high tracking and vertexing efficiencies, is studied. Measurements of the single-channel random noise are presented together with studies of common mode noise and measurements of the noise occupancy using a random trigger generator. (orig.)

  15. Analytical study of interior noise control by fuselage design techniques on high-speed, propeller-driven aircraft

    Science.gov (United States)

    Revell, J. D.; Balena, F. J.; Koval, L. R.

    1980-01-01

    The acoustical treatment mass penalties required to achieve an interior noise level of 80 dBA for high speed, fuel efficient propfan-powered aircraft are determined. The prediction method used is based on theory developed for the outer shell dynamics, and a modified approach for add-on noise control element performance. The present synthesis of these methods is supported by experimental data. Three different sized aircraft are studied, including a widebody, a narrowbody and a business sized aircraft. Noise control penalties are calculated for each aircraft for two kinds of noise control designs: add-on designs, where the outer wall structure cannot be changed, and advanced designs where the outer wall stiffness level and the materials usage can be altered. For the add-on designs, the mass penalties range from 1.7 to 2.4 percent of the takeoff gross weight (TOGW) of the various aircraft, similar to preliminary estimates. Results for advanced designs show significant reductions of the mass penalties. For the advanced aluminum designs the penalties are 1.5% of TOGW, and for an all composite aircraft the penalties range from 0.74 to 1.4% of TOGW.

  16. Investigating optimal technique in the presence of motor system noise: application to the double layout somersault dismount on high bar.

    Science.gov (United States)

    Hiley, Michael J; Yeadon, Maurice R

    2016-01-01

    Minimising joint torque is often used as an optimisation criterion when investigating human movement. Alternatively, an aspect of performance may be chosen to be maximised when investigating sporting movements. The aim of the study was to optimise the technique in the backward giant circle prior to a double layout somersault dismount from the high bar using various criteria to determine which best characterised the technique adopted by a gymnast. Ten recorded gymnast trials were used to determine bar release parameters and the level of noise in the gymnast's movements. A computer simulation model of a gymnast and bar was used to optimise giant circle technique under three criteria: minimising joint torques, maximising the release window and maximising success in the presence of motor system noise. Local and global optimisations of technique were performed using the three criteria starting from the average technique of the 10 recorded trials. All global optimum solutions diverged from the gymnast's technique. The local optimum for maximising success in the presence of noise had a success rate comparable with the global optimum (98% vs. 100%, respectively). It is concluded that the gymnast's technique is characterised by maximising success despite operating with motor system noise.

  17. Dual-frequency Brillouin fiber laser for optical generation of tunable low-noise radio frequency/microwave frequency.

    Science.gov (United States)

    Geng, Jihong; Staines, Sean; Jiang, Shibin

    2008-01-01

    We demonstrate a new approach, i.e., a cw dual-frequency Brillouin fiber laser pumped by two independent single-frequency Er-doped fiber lasers, for the generation of tunable low-noise rf/microwave optical signals. Its inherent features of both linewidth narrowing effect in a Brillouin fiber cavity and common mode noise cancellation between two laser modes sharing a common cavity allow us to achieve high frequency stability without using a supercavity. Beat frequency of the dual-frequency Brillouin fiber laser can be tuned from tens of megahertz up to 100 GHz by thermally tuning the wavelengths of the two pump lasers with tuning sensitivity of approximately 1.4 GHz/ degrees C. Allan variance measurements show the beat signals have the hertz-level frequency stability.

  18. Non-Linear Dynamical Classification of Short Time Series of the Rössler System in High Noise Regimes

    Science.gov (United States)

    Lainscsek, Claudia; Weyhenmeyer, Jonathan; Hernandez, Manuel E.; Poizner, Howard; Sejnowski, Terrence J.

    2013-01-01

    Time series analysis with delay differential equations (DDEs) reveals non-linear properties of the underlying dynamical system and can serve as a non-linear time-domain classification tool. Here global DDE models were used to analyze short segments of simulated time series from a known dynamical system, the Rössler system, in high noise regimes. In a companion paper, we apply the DDE model developed here to classify short segments of encephalographic (EEG) data recorded from patients with Parkinson’s disease and healthy subjects. Nine simulated subjects in each of two distinct classes were generated by varying the bifurcation parameter b and keeping the other two parameters (a and c) of the Rössler system fixed. All choices of b were in the chaotic parameter range. We diluted the simulated data using white noise ranging from 10 to −30 dB signal-to-noise ratios (SNR). Structure selection was supervised by selecting the number of terms, delays, and order of non-linearity of the model DDE model that best linearly separated the two classes of data. The distances d from the linear dividing hyperplane was then used to assess the classification performance by computing the area A′ under the ROC curve. The selected model was tested on untrained data using repeated random sub-sampling validation. DDEs were able to accurately distinguish the two dynamical conditions, and moreover, to quantify the changes in the dynamics. There was a significant correlation between the dynamical bifurcation parameter b of the simulated data and the classification parameter d from our analysis. This correlation still held for new simulated subjects with new dynamical parameters selected from each of the two dynamical regimes. Furthermore, the correlation was robust to added noise, being significant even when the noise was greater than the signal. We conclude that DDE models may be used as a generalizable and reliable classification tool for even small segments of noisy data. PMID

  19. Non-linear Dynamical Classification of Short Time Series of the Rössler System in High Noise Regimes

    Directory of Open Access Journals (Sweden)

    Claudia eLainscsek

    2013-11-01

    Full Text Available Time series analysis with delay differential equations (DDEs reveals nonlinear properties of the underlying dynamical system and can serve as a non-linear time-domain classification tool. Here global DDE models were used to analyze short segments of simulated time series from a known dynamical system, the Rössler system, in high noise regimes. In a companion paper, we apply the DDE model developed here to classify short segments of encephalographic (EEG data recorded from patients with Parkinson's disease and healthy subjects. Nine simulated subjects in each of two distinct classes were generated by varying the bifurcation parameter b and keeping the other two parameters (a and c of the Rössler system fixed. All choices of b were in the chaotic parameter range. We diluted the simulated data using white noise ranging from 10dB to -30dB signal-to-noise ratios (SNR. Structure selection was supervised by selecting the number of terms, delays, and order of nonlinearity of the model DDE model that best linearly separated the two classes of data. The distances d from the linear dividing hyperplane was then used to assess the classification performance by computing the area A' under the ROC curve. The selected model was tested on untrained data using repeated random sub-sampling validation. DDEs were able to accurately distinguish the two dynamical conditions, and moreover, to quantify the changes in the dynamics. There was a significant correlation between the dynamical bifurcation parameter b of the simulated data and the classification parameter d from our analysis. This correlation still held for new simulated subjects with new dynamical parameters selected from each of the two dynamical regimes. Furthermore, the correlation was robust to added noise, being significant even when the noise was greater than the signal. We conclude that DDE models may be used as a generalizable and reliable classification tool for even small segments of noisy data.

  20. Investigations for low noise cooling by means of a pulse tube cooler for highly sensitive SQUID magnetometers from high temperature superconductors

    CERN Document Server

    Lienerth, C

    2000-01-01

    110fT/[Root]Hz at 10 Hz. For the discret peaks at the working frequency the vibration compensation is capable of reducing the cooler-generated peaks in the field noise spectrum by a factor of the order of 4. This noise level is low enough for applications such as nondestructive evaluation of materials. For identifying the origin of the remaining disturbances, one has to consider in addition to the residual vibrations also temperature oscillations and oscillating fields from eddy current at the SQUID location. The commercial acceptance of superconducting applications is closely associated with the availability of appropriate cryocoolers that enable continuous operation without the need to re-fill liquid cryogens. For cooling of highly-sensitive HT-SQUID sensors the cryocooler has to meet rather severe demands concerning interference from the cooler itself. In particular, cooler-generated noise from electromagnetic interference (EMI), mechanical vibrations and temperature fluctuations should be below the intrin...

  1. A high-efficiency, low-noise power solution for a dual-channel GNSS RF receiver

    Science.gov (United States)

    Jian, Shi; Taishan, Mo; Jianlian, Le; Yebing, Gan; Chengyan, Ma; Tianchun, Ye

    2012-08-01

    A high-efficiency low-noise power solution for a dual-channel GNSS RF receiver is presented. The power solution involves a DC—DC buck converter and a followed low-dropout regulator (LDO). The pulse-width-modulation (PWM) control method is adopted for better noise performance. An improved low-power high-frequency PWM control circuit is proposed, which halves the average quiescent current of the buck converter to 80 μA by periodically shutting down the OTA. The size of the output stage has also been optimized to achieve high efficiency under a light load condition. In addition, a novel soft-start circuit based on a current limiter has been implemented to avoid inrush current. Fabricated with commercial 180-nm CMOS technology, the DC—DC converter achieves a peak efficiency of 93.1% under a 2 MHz working frequency. The whole receiver consumes only 20.2 mA from a 3.3 V power supply and has a noise figure of 2.5 dB.

  2. Multiple testing issues in discriminating compound-related peaks and chromatograms from high frequency noise, spikes and solvent-based nois in LC-MS data sets

    NARCIS (Netherlands)

    Nyangoma, S.O.; Van Kampen, A.A.; Reijmers, T.H.; Govorukhina, N.I; van der Zee, A.G.; Billingham, I.J; Bischoff, Rainer; Jansen, R.C.

    2007-01-01

    Multiple testing issues in discriminating compound-related peaks and chromatograms from high frequency noise, spikes and solvent-based noise in LC-MS data sets.Nyangoma SO, van Kampen AA, Reijmers TH, Govorukhina NI, van der Zee AG, Billingham LJ, Bischoff R, Jansen RC. University of Birmingham. Liq

  3. Users' manual for the Langley high speed propeller noise prediction program (DFP-ATP)

    Science.gov (United States)

    Dunn, M. H.; Tarkenton, G. M.

    1989-01-01

    The use of the Dunn-Farassat-Padula Advanced Technology Propeller (DFP-ATP) noise prediction program which computes the periodic acoustic pressure signature and spectrum generated by propellers moving with supersonic helical tip speeds is described. The program has the capacity of predicting noise produced by a single-rotation propeller (SRP) or a counter-rotation propeller (CRP) system with steady or unsteady blade loading. The computational method is based on two theoretical formulations developed by Farassat. One formulation is appropriate for subsonic sources, and the other for transonic or supersonic sources. Detailed descriptions of user input, program output, and two test cases are presented, as well as brief discussions of the theoretical formulations and computational algorithms employed.

  4. FROST: a low-noise high-rate photon counting ASIC for X-ray applications

    Energy Technology Data Exchange (ETDEWEB)

    Prest, M. E-mail: prest@ts.infn.it; Vallazza, E.; Chiavacci, M.; Mariani, R.; Motto, S.; Neri, M.; Scantamburlo, N.; Arfelli, F.; Conighi, A.; Longo, R.; Olivo, A.; Pani, S.; Poropat, P.; Rashevsky, A.; Rigon, L.; Tromba, G.; Castelli, E

    2001-04-01

    FRONTier RADiography is an R and D project to assess the feasibility of digital mammography with Synchrotron Radiation at the ELETTRA Light Source in Trieste. In order to reach an acceptable time duration of the exam, a fast- and low-noise photon counting ASIC has been developed in collaboration with Aurelia Microelettronica, called Frontrad ReadOut SysTem. It is a multichannel counting system, each channel being made of a low-noise charge-sensitive preamplifier optimized for X-ray energy range (10-100 keV), a CR-RC{sup 2} shaper, a discriminator and a 16-bit counter. In order to set the discriminator threshold, a set of a global 6-bit DAC and a local (per channel) 3-bit DAC has been implemented within the ASIC. We report on the measurements done with the 8-channel prototype chip and the comparison with the simulation results.

  5. Noise properties of high-quality step-edge YBCO Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Foley, C.P.; Lam, S.; Sloggett, J.; Savvides, N; Katsaros, A. [CSIRO, Lindfield, NSW (Australia). Division of Applied Physics; Hao, L.; Macfarlane, J.C.; Pegrum, C.M. [University of Strathclyde, Glasgow (United Kingdom). Department of Physics and Applied Physics; Kuznik, J. [Czech Academy of Science, Prague (Czech Republic).

    1996-12-31

    Full text: We report the results of noise and other measurements on YBCO step-edge Josephson junctions whose morphology closely approaches the ideal of a homogeneous tilt angle grain boundary. The junctions exhibit near-perfect resistively-shunted-junction (RSJ) current voltage characteristics and magnetic field dependence. Excess noise in the junctions was comparable to the best bicrystal types previously measured, the normalised amplitude of the critical current fluctuations, S{sub i}{sup 1/2}, being less than 1x10{sub -4} Hz{sub -}1{sub /2} at 1 Hz and 77 K. S{sub i}{sup 1/2} was found to be independent of temperature and also independent of magnetic field provided the zero-field critical current was used for normalisation

  6. Effect of Heating on Turbulent Density Fluctuations and Noise Generation From High Speed Jets

    Science.gov (United States)

    Panda, Jayanta; Seasholtz, Richard G.; Elam, Kristie A.; Mielke, Amy F.; Eck, Dennis G.

    2004-01-01

    Heated jets in a wide range of temperature ratios (TR), and acoustic Mach numbers (Ma) were investigated experimentally using far field microphones and a molecular Rayleigh scattering technique. The latter provided density fluctuations measurements. Two sets of operating conditions were considered: (1) TR was varied between 0.84 and 2.7 while Ma was fixed at 0.9; (2) Ma was varied between 0.6 and 1.48, while TR was fixed at 2.27. The implementation of the molecular Rayleigh scattering technique required dust removal and usage of a hydrogen combustor to avoid soot particles. Time averaged density measurements in the first set of data showed differences in the peripheral density shear layers between the unheated and heated jets. The nozzle exit shear layer showed increased turbulence level with increased plume temperature. Nevertheless, further downstream the density fluctuations spectra are found to be nearly identical for all Mach number and temperature ratio conditions. To determine noise sources a correlation study between plume density fluctuations and far field sound pressure fluctuations was conducted. For all jets the core region beyond the end of the potential flow was found to be the strongest noise source. Except for an isothermal jet, the correlations did not differ significantly with increasing temperature ratio. The isothermal jet created little density fluctuations. Although the far field noise from this jet did not show any exceptional trend, the flow-sound correlations were very low. This indicated that the density fluctuations only acted as a "tracer parameter" for the noise sources.

  7. High-resolution shallow structure revealed with ambient noise tomography on a dense array

    Science.gov (United States)

    Zeng, X.; Thurber, C. H.; Luo, Y.; Matzel, E.; Team, P.

    2016-12-01

    A dense seismic array was deployed by the PoroTomo research team at Brady Hot Springs, Nevada in March 2016. The array consisted of 238 short-period three-component geophones (5-Hz corner frequency) with about 60 m spacing. Over the 15 day deployment, the array recorded over 6,000 active source signals (vibroseis sweeps) and ambient noise that was dominated by traffic noise.We adopted the one-bit method to better reduce the effect of the active source. Spectral whitening was performed between 0.5 and 2 Hz. The continuous record was chopped into 1 minute segments. The 1-minute cross-correlation functions were initially stacked linearly, and then the phase-weighted stacking method was applied to improve signal quality. More than two million noise correlation functions (NCFs) have been obtained.The Rayleigh wave group velocity was measured on the symmetric component of the NCFs with the frequency-time analysis method. The average group velocity is about 400 m/s at 4 Hz, which is consistent with preliminary active source result. To avoid mis-picking possible precursors, the arrival time was picked at the peak in a two-second time window predicted with the average group velocity of the fundamental mode. The quality of the arrival measurements is defined by the signal-to-noise ratio. We were able to pick reliable arrivals at about 35% of the station-pairs. Since the straight-ray assumption may not be valid in a strongly heterogeneous medium, the wave path was traced with a finite difference scheme and the LSQR method was utilized to invert group velocity. The heterogeneous features of the group velocity map are consistent with a local geologic map. The PoroTomo project is funded by a grant from the U.S. Department of Energy.

  8. High background noise shapes selective auditory filters in a tropical cricket.

    Science.gov (United States)

    Schmidt, Arne K D; Riede, Klaus; Römer, Heiner

    2011-05-15

    Because of call frequency overlap and masking interference, the airborne sound channel represents a limited resource for communication in a species-rich cricket community like the tropical rainforest. Here we studied the frequency tuning of an auditory neuron mediating phonotaxis in the rainforest cricket Paroecanthus podagrosus, suffering from strong competition, in comparison with the same homologous neuron in two species of European field crickets, where such competition does not exist. As predicted, the rainforest species exhibited a more selective tuning compared with the European counterparts. The filter reduced background nocturnal noise levels by 26 dB, compared with only 16 and 10 dB in the two European species. We also quantified the performance of the sensory filter under the different filter regimes by examining the representation of the species-specific amplitude modulation of the male calling song, when embedded in background noise. Again, the filter of the rainforest cricket performed significantly better in terms of representing this important signal parameter. The neuronal representation of the calling song pattern within receivers was maintained for a wide range of signal-to-noise ratios because of the more sharply tuned sensory system and selective attention mechanisms. Finally, the rainforest cricket also showed an almost perfect match between the filter for sensitivity and the peripheral filter for directional hearing, in contrast to its European counterparts. We discuss the consequences of these adaptations for intraspecific acoustic communication and reproductive isolation between species.

  9. Cogging Torque and Acoustic Noise Reduction in High Torque BLDC Motors by Teeth Pairings

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Min [Halla Climate Control Co. (Korea, Republic of); Hwang, Sang Moon [Pusan National University (Korea, Republic of)

    1999-03-01

    This paper investigates reduction of acoustic noise and cogging torque in a BLDC motor with larger stator slot open width. Using energy method, cogging torque is analytically determined with airgap MMF function and airgap permeance function and confirmed by FEM analysis. It show that the cogging torque is firstly governed by N{sub L} G{sub NL} B{sub NL} with the fundamental period of N{sub L}, where N{sub L} is the least common multiple of the number of slots and the number of poles, G{sub NL}, airgap permeance function and B{sub NL}, airgap MMF function. It also shows that there exist several tooth width which minimizes the cogging torque, for the motors that smaller slot open width or stator teeth notching is not available. And it proposes a teeth pairing with two different tooth width which can effectively eliminate the cogging torque and thus the acoustic noise. Experimental results show that the proposed teeth pairing reduces the cogging torque by 85% and the acoustic noise by 3.1 dB. (author). 9 refs., 13 figs., 1 tab.

  10. A 2.4 GHz high-linearity low-phase-noise CMOS LC-VCO based on capacitance compensation

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhenrong; Zhuang Yiqi; Li Bing; Jin Gang; Jin Zhao, E-mail: allen_lzr@126.co [Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2010-07-15

    A 2.4 GHz high-linearity low-phase-noise cross-coupled CMOS LC voltage-controlled oscillator (VCO) is implemented in standard 0.18-{mu}m CMOS technology. An equalization structure for tuning sensitivity base on the three-stage distributed biased switched-varactor bank and the differential switched-capacitor bank is adopted to reduce the variations of the VCO gain, achieve high linearity, and optimize the phase-noise performance. Compared to the conventional VCO, the proposed VCO has more constant gain over the entire tuning range. The tuning range is about 18.7% from 2.23 to 2.69 GHz, and the phase noise is -95 dBc/Hz at 100-kHz offset and -117 dBc/Hz at 1-MHz offset from the carrier frequency of 2.42 GHz. The power dissipation is 2.1 mW from a 1.8 V power supply. The active area of this VCO is 500 x 810 {mu}m{sup 2}.

  11. HIGH-THROUGHPUT TECHNOLOGIES FOR GENE EXPRESSION ANALYSES:WHAT WE HAVE LEARNED FOR NOISE-INDUCED COCHLEAR DEGENERATION

    Institute of Scientific and Technical Information of China (English)

    Hu Bo Hua

    2013-01-01

    Noise-induced hearing loss is a common cause of acquired hearing loss in the adult population. Acoustic overstimulation causes cochlear damage through mechanical stress to the tissue. Consequently, complex molec-ular changes are initiated, and these changes lead to morphological and biological alterations in the cochlea, which in turn compromise the cochlear function and cause hearing loss. In the past 10 years, there have been significant advances in our understanding of the molecular mechanisms of noise-induced hearing loss. These advances are attributed, in part, to the development of high-throughput technologies for the global analyses of molecular changes. In this review, we briefly describe the newly developed methods for investigating the mo-lecular responses of the cochlea to acoustic trauma and the knowledge generated from these studies. We also discuss the strengths and limitations of each technique and the major challenges to investigate cochlear degen-eration following acoustic injury.

  12. A Review on Natural Ventilation-enabling Façade Noise Control Devices for Congested High-Rise Cities

    Directory of Open Access Journals (Sweden)

    Shiu-Keung Tang

    2017-02-01

    Full Text Available This review summarizes the current status of the research and development of natural ventilation-enabling noise control devices for use on the façades of high-rise residential buildings in congested cities. These devices are important for a sustainable urbanized city, as they are supposed to offer good acoustical protection to citizens, allowing for an acceptable level of natural ventilation inside residential units; energy for mechanical ventilation can then be saved. From the information presented in the existing literature, it is concluded that protrusive devices, such as lintels and balconies, are not effective noise screening devices, even if they are installed with sound absorbers and/or reflectors, under the effect of city reverberation. On the contrary, plenum windows and similar structures, which are plenum structures with a staggered air inlet and outlet, are interesting alternatives that are worth rigorous considerations.

  13. Noise Gating Solar Images

    Science.gov (United States)

    DeForest, Craig; Seaton, Daniel B.; Darnell, John A.

    2017-08-01

    I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO

  14. TIPS bilateral noise reduction in 4D CT perfusion scans produces high-quality cerebral blood flow maps

    Energy Technology Data Exchange (ETDEWEB)

    Mendrik, Adrienne M; Van Ginneken, Bram; Viergever, Max A [Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Vonken, Evert-jan; De Jong, Hugo W; Riordan, Alan; Van Seeters, Tom; Smit, Ewoud J; Prokop, Mathias, E-mail: a.m.mendrik@gmail.com [Radiology Department, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)

    2011-07-07

    Cerebral computed tomography perfusion (CTP) scans are acquired to detect areas of abnormal perfusion in patients with cerebrovascular diseases. These 4D CTP scans consist of multiple sequential 3D CT scans over time. Therefore, to reduce radiation exposure to the patient, the amount of x-ray radiation that can be used per sequential scan is limited, which results in a high level of noise. To detect areas of abnormal perfusion, perfusion parameters are derived from the CTP data, such as the cerebral blood flow (CBF). Algorithms to determine perfusion parameters, especially singular value decomposition, are very sensitive to noise. Therefore, noise reduction is an important preprocessing step for CTP analysis. In this paper, we propose a time-intensity profile similarity (TIPS) bilateral filter to reduce noise in 4D CTP scans, while preserving the time-intensity profiles (fourth dimension) that are essential for determining the perfusion parameters. The proposed TIPS bilateral filter is compared to standard Gaussian filtering, and 4D and 3D (applied separately to each sequential scan) bilateral filtering on both phantom and patient data. Results on the phantom data show that the TIPS bilateral filter is best able to approach the ground truth (noise-free phantom), compared to the other filtering methods (lowest root mean square error). An observer study is performed using CBF maps derived from fifteen CTP scans of acute stroke patients filtered with standard Gaussian, 3D, 4D and TIPS bilateral filtering. These CBF maps were blindly presented to two observers that indicated which map they preferred for (1) gray/white matter differentiation, (2) detectability of infarcted area and (3) overall image quality. Based on these results, the TIPS bilateral filter ranked best and its CBF maps were scored to have the best overall image quality in 100% of the cases by both observers. Furthermore, quantitative CBF and cerebral blood volume values in both the phantom and the

  15. TIPS bilateral noise reduction in 4D CT perfusion scans produces high-quality cerebral blood flow maps

    Science.gov (United States)

    Mendrik, Adriënne M.; Vonken, Evert-jan; van Ginneken, Bram; de Jong, Hugo W.; Riordan, Alan; van Seeters, Tom; Smit, Ewoud J.; Viergever, Max A.; Prokop, Mathias

    2011-07-01

    Cerebral computed tomography perfusion (CTP) scans are acquired to detect areas of abnormal perfusion in patients with cerebrovascular diseases. These 4D CTP scans consist of multiple sequential 3D CT scans over time. Therefore, to reduce radiation exposure to the patient, the amount of x-ray radiation that can be used per sequential scan is limited, which results in a high level of noise. To detect areas of abnormal perfusion, perfusion parameters are derived from the CTP data, such as the cerebral blood flow (CBF). Algorithms to determine perfusion parameters, especially singular value decomposition, are very sensitive to noise. Therefore, noise reduction is an important preprocessing step for CTP analysis. In this paper, we propose a time-intensity profile similarity (TIPS) bilateral filter to reduce noise in 4D CTP scans, while preserving the time-intensity profiles (fourth dimension) that are essential for determining the perfusion parameters. The proposed TIPS bilateral filter is compared to standard Gaussian filtering, and 4D and 3D (applied separately to each sequential scan) bilateral filtering on both phantom and patient data. Results on the phantom data show that the TIPS bilateral filter is best able to approach the ground truth (noise-free phantom), compared to the other filtering methods (lowest root mean square error). An observer study is performed using CBF maps derived from fifteen CTP scans of acute stroke patients filtered with standard Gaussian, 3D, 4D and TIPS bilateral filtering. These CBF maps were blindly presented to two observers that indicated which map they preferred for (1) gray/white matter differentiation, (2) detectability of infarcted area and (3) overall image quality. Based on these results, the TIPS bilateral filter ranked best and its CBF maps were scored to have the best overall image quality in 100% of the cases by both observers. Furthermore, quantitative CBF and cerebral blood volume values in both the phantom and the

  16. A comparative study of noise in supercontinuum light sources for ultra-high resolution optical coherence tomography

    DEFF Research Database (Denmark)

    Maria J., Sanjuan-Ferrer,; Bravo Gonzalo, Ivan; Bondu, Magalie

    2017-01-01

    Supercontinuum (SC) light is a well-established technology, which finds applications in several domains ranging from chemistry to material science and imaging systems [1-2]. More specifically, its ultra-wide optical bandwidth and high average power make it an ideal tool for Optical Coherence...... Tomography (OCT). Over the last 5 years, numerous examples have demonstrated its high potential [3-4] in this context. However, SC light sources present pulse-to-pulse intensity variation that can limit the performance of any OCT system [5] by degrading their signal to noise ratio (SNR). To this goal, we...

  17. Comparative Analysis of Different PWM Techniques to Reduce the Common Mode Voltage in Three-Level Neutral-Point-Clamped Inverters for Variable Speed Induction Drives

    Directory of Open Access Journals (Sweden)

    Bharati Raja

    2012-12-01

    Full Text Available This work presents the comparative study of the different PWM techniques to reduce the common-mode voltage (CMV at the output of neutral point diode clamped inverter for variable speed drives. Here the comparative study is done by the phase opposition disposed (POD, sinusoidal pulse width modulation (SPWM, phase disposition (PD, phase shift (PS space vector modulation (SVM techniques are proposed. A good trade-off between the quality of the output voltage and the partial magnitude of the CMV is achieved in this work. The scheme is proposed for three-level inverter. This work realizes the implementation of Three-level diode clamped MLI for three-phase (Y-Δ induction motor with the implementation of a space vector modulation technique without any additional control algorithm to reduce CMV within the range + Vdc/6. The Simulation with a 1HP induction motor drive system is setup in Matlab-2011b  and the same results validated effectively by hardware – FPGA-SPARTEN III processor and its shows that the CM voltage is effectively reduced and the maximum output voltage is not affected.  

  18. Low Noise and Highly Linear Wideband CMOS RF Front-End for DVB-H Direct-Conversion Receiver

    Science.gov (United States)

    Nam, Ilku; Moon, Hyunwon; Woo, Doo Hyung

    In this paper, a wideband CMOS radio frequency (RF) front-end for digital video broadcasting-handheld (DVB-H) receiver is proposed. The RF front-end circuit is composed of a single-ended resistive feedback low noise amplifier (LNA), a single-to-differential amplifier, an I/Q down-conversion mixer with linearized transconductors employing third order intermodulation distortion cancellation, and a divide-by-two circuit with LO buffers. By employing a third order intermodulation (IMD3) cancellation technique and vertical NPN bipolar junction transistor (BJT) switching pair for an I/Q down-conversion mixer, the proposed RF front-end circuit has high linearity and low low-frequency noise performance. It is fabricated in a 0.18µm deep n-well CMOS technology and draws 12mA from a 1.8V supply voltage. It shows a voltage gain of 31dB, a noise figure (NF) lower than 2.6dB, and an IIP3 of -8dBm from 470MHz to 862MHz.

  19. Noise reduction methods in analysis of near infrared lunar occultation light curves for high angular resolution measurements

    CERN Document Server

    Baug, Tapas

    2013-01-01

    Lunar occultation (LO) technique in the near-infrared provides angular resolution down to milliarcseconds on the occulted source even with ground-based 1m class telescopes. LO observations are limited to brighter objects because they require high signal to noise ratio (S/N ~ 40) for proper extraction of angular diameter values. Hence, methods to improve the S/N ratio by reducing noise using Fourier and Wavelet transforms have been explored in this study. A sample of 54 near-infrared LO light curves observed with IR Camera at Mt Abu observatory has been used. It is seen that both Fourier and Wavelet methods have shown improvement in S/N, compared to the original data. However, the application of wavelet transforms results in slight smoothening of the fringes resulting in a higher angular diameter value. Fourier transforms which reduce discrete noise frequencies do not distort the fringe. Fourier transform method seems to be effective in S/N improvement, as well as improved model fit particularly in the fainter...

  20. Very High Current Density Nb/AlN/Nb Tunnel Junctions for Low-Noise Submillimeter Mixers

    Science.gov (United States)

    Kawamura, Jonathan; Miller, David; Chen, Jian; Zmuidzinas, Jonas; Bumble, Bruce; LeDuc, Henry G.; Stern, Jeff A.

    2000-01-01

    We have fabricated and tested submillimeter-wave superconductor-insulator-superconductor (SIS) mixers using very high current density Nb/AlN/Nb tunnel junctions (J(sub c) approximately equal 30 kA/sq cm) . The junctions have low resistance-area products (R(sub N)A approximately 5.6 Omega.sq micron), good subgap to normal resistance ratios R(sub sg)/R(sub N) approximately equal 10, and good run-to-run reproducibility. From Fourier transform spectrometer measurements, we infer that omega.R(sub N)C = 1 at 270 GHz. This is a factor of 2.5 improvement over what is generally available with Nb/AlO(x)/Nb junctions suitable for low-noise mixers. The AlN-barrier junctions are indeed capable of low-noise operation: we measure an uncorrected receiver noise temperature of T(sub RX) = 110 K (DSB) at 533 GHz for an unoptimized device. In addition to providing wider bandwidth operation at lower frequencies, the AlN-barrier junctions will considerably improve the performance of THz SIS mixers by reducing RF loss in the tuning circuits.

  1. New high resolution Random Telegraph Noise (RTN) characterization method for resistive RAM

    Science.gov (United States)

    Maestro, M.; Diaz, J.; Crespo-Yepes, A.; Gonzalez, M. B.; Martin-Martinez, J.; Rodriguez, R.; Nafria, M.; Campabadal, F.; Aymerich, X.

    2016-01-01

    Random Telegraph Noise (RTN) is one of the main reliability problems of resistive switching-based memories. To understand the physics behind RTN, a complete and accurate RTN characterization is required. The standard equipment used to analyse RTN has a typical time resolution of ∼2 ms which prevents evaluating fast phenomena. In this work, a new RTN measurement procedure, which increases the measurement time resolution to 2 μs, is proposed. The experimental set-up, together with the recently proposed Weighted Time Lag (W-LT) method for the analysis of RTN signals, allows obtaining a more detailed and precise information about the RTN phenomenon.

  2. Microwave noise emission from high /ital T//sub /ital c// thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jung, G.; Konopka, J.; Gierlowski, P.; Kula, W.

    1989-06-05

    A pronounced /ital X/-band microwave noise emission from Y-Ba-Cu-O thin filmshas been observed. Emission depends strongly on temperture, bias current, andmagnetic field. Two types of emission lines can be distinguished in the powerversus dc bias spectra. The lines which remain at stable current positionsagainst temperature we tentatively ascribe to the interaction of depinned fluxflow with a two-dimensional Josephson junction array. The lines that appear atfixed voltage positions may be attributed to the Josephson radiation of adistributed network of junctions. No significant emission was detected fromBi-Ca-Sr-Cu-O films.

  3. A simple technique for high resolution time domain phase noise measurement

    Science.gov (United States)

    Reinhardt, V. S.; Donahoe, T.

    1977-01-01

    A new time domain phase comparator is described. The device uses a novel technique to allow time domain phase measurements to be made with period and time interval counters without the use of offset reference oscillators. The device uses a single reference oscillator and allows measurements with a phase resolution greater than the noise floor of the reference. Data is presented showing a phase resolution of 0.02ps at 5 MHz with a crystal reference. The device has application in measuring the phase stability of systems where approximate phase quadrature can be maintained.

  4. 基于航空噪声指标的高速列车观光区噪声评价%Noise Evaluation in the Tourist Cabin of High-speed Train by Using Aircraft Noise Criterion

    Institute of Scientific and Technical Information of China (English)

    张捷; 肖新标; 张玉梅; 王瑞乾; 王谛; 金学松

    2013-01-01

    Based on field measurements,the noise characteristics in the tourist cabin of a high-speed train are analyzed at a high running speed between 300 to 400 km/h.So far,there is still no a unified criterion in the word to evaluate the noise level in the carriage of high-speed train reasonably,while A-weighted sound level has a shortcoming in the noise evaluation.In order to further clear the shortcoming,A-weighted sound level is discussed through the detailed contrast to white noise combined with increasing sound level in different frequency bands.An aircraft noise evaluation index is used to evaluate the interior noise of the high-speed train.The obtained results indicate that:the noise in the tourist cabin of the high-speed train is dominated by the components of low and middle frequencies.Such a noise would be underestimated when A-weighted sound level is used.There is high similarity of frequency characteristics between interior noise of high-speed train and it of aircraft.The aircraft noise evaluation index is more suitable for the characteristic evaluation of interior noise of high-speed train.This paper could provide evidence for framing new proper noise evaluation criterion for high-speed train.%基于现场测试结果,对300~400 km/h速度下高速列车观光区噪声进行分析,明确车内噪声动态特性.由于国内外还没有统一的高速列车车内噪声评价标准,传统的A计权声压级又在噪声评价中存在不足之处.为研究A计权声压级是否适合高速列车车内噪声评价,通过白噪声对比、分频段声压级比例增加等方法,讨论使用A计权声压级评价车内噪声时的不足之处.运用航空噪声评价指标对高速列车车内噪声进行评价研究.研究结果表明,300 km/h以上高速列车车内噪声具有显著的中低频特性,使用A计权声压级评价会低估车内噪声水平.高速列车观光区噪声频谱特性和飞机舱内噪声频谱特性具有很高的相似性,选择

  5. A Carrier-Phase Control Suitable for Conducted EMI Noise Reduction in a Multiple-Converter System

    Science.gov (United States)

    Tamate, Michio; Toba, Akio; Matsumoto, Yasushi; Wada, Keiji; Shimizu, Toshihisa

    Conducted EMI noise flowing from the power converters to AC utility line is regulated by international commissions such as International Electrotechnical Commission (IEC). For adherence to the IEC regulations, EMI filters should be used in power electronics equipment. This paper proposes a method for analyzing the conducted EMI noise in multiple power converters connected to the same power line. In this method, the phase difference between sub-harmonic modulated carrier signals at each power converter is taken into account. The phase difference among the power converters determines the EMI noise level in a multiple-converter system, as is evident from the analysis of the waveform of the common-mode current. In addition, EMI noise suppression using a carrier-phase control is a proposed. In order to reduce volume of the EMI filter effectively, the phase difference θ should be set to 360/nN° here, n is a high-order harmonic component at around 150kHz, and N is the number of power converters. Therefore, the conducted EMI noise can be reduced effectively with the help of the proposed phase control.

  6. Low noise high-speed X-ray readout IC for imaging applications

    CERN Document Server

    Tsakas, E F; Manthos, N; Kloukinas, K; Evangelou, I; Triantis, F A; Stelt, P F V D; Speller, R D

    2001-01-01

    We present a mixed-signal, continuously sensitive, self-triggered IC designed for X-ray imaging applications. Both bipolar and CMOS devices were employed in order to achieve the speed and noise requirements associated with the particular application. Phenomena related to the submicron nature of the devices used have been also taken into consideration. The circuit is optimized to operate with a 3 pF Si-microstrip detector and it exhibits an equivalent noise charge of 225e sup - rms with a slope of 45e sup - /pF. The peaking time of the pulse at the output of the analog part is 28 ns and the circuit recovers to the baseline within 600 ns. Moreover, it has the ability of handling either positive or negative current pulses originating from the detector. The IC power consumption is 4.5 mW per channel and the chip was fabricated using a 0.8 mu m BiCMOS technology.

  7. Separation of rolling noise and aerodynamic noise by in-service measurement of combined roughness and transfer functions on a high speed slab track

    NARCIS (Netherlands)

    Jansen, H.W.; Dittrich, M.G.

    2012-01-01

    Combined sound and vibration measurements during train pass-bys can be used to quantify contributions from the excitation and transmission of rolling noise. This is useful for the identification of sound sources and the assessment of the track contribution. In this paper, a practical application on

  8. Separation of rolling noise and aerodynamic noise by in-service measurement of combined roughness and transfer functions on a high speed slab track

    NARCIS (Netherlands)

    Jansen, H.W.; Dittrich, M.G.

    2012-01-01

    Combined sound and vibration measurements during train pass-bys can be used to quantify contributions from the excitation and transmission of rolling noise. This is useful for the identification of sound sources and the assessment of the track contribution. In this paper, a practical application on

  9. X-ray imaging with ePix100a: a high-speed, high-resolution, low-noise camera

    Science.gov (United States)

    Blaj, G.; Caragiulo, P.; Dragone, A.; Haller, G.; Hasi, J.; Kenney, C. J.; Kwiatkowski, M.; Markovic, B.; Segal, J.; Tomada, A.

    2016-09-01

    The ePix100A camera is a 0.5 megapixel (704 x 768 pixels) camera for low noise x-ray detection applications requiring high spatial and spectral resolution. The camera is built around a hybrid pixel detector consisting of 4 ePix100a ASICs ip-chip bonded to one sensor. The pixels are 50 μm x 50 μm (active sensor size 35:4mm x 38:6 mm), with a noise of 180 eV rms, a range of 100 8 keV photons, and a current frame rate of 240 Hz (with an upgrade path towards 10 kHz). This performance leads to a camera combining a high dynamic range, high signal to noise ratio, high speed and excellent linearity and spectroscopic performance. While the ePix100A ASIC has been developed for pulsed source applications (e.g., free-electron lasers), it performs well with more common sources (e.g., x-ray tubes, synchrotron radiation). Several cameras have been produced and characterized and the results are reported here, along with x-ray imaging applications demonstrating the camera performance.

  10. Data for The flow and flow-induced noise behaviour of a simplified high-speed train bogie in a cavity and including a fairing

    OpenAIRE

    Zhu, Jianyue; Hu, Zhiwei; Thompson, David

    2017-01-01

    Dataset for the main results of paper entitled 'The flow and flow-induced noise behaviour of a simplified high-speed train bogie in a cavity and including a fairing' published in Journal of Rail and Rapid Transit.

  11. MIMO Radar Transceiver Design for High Signal-to-Interference-Plus-Noise Ratio

    KAUST Repository

    Lipor, John

    2013-05-12

    Multiple-input multiple-output (MIMO) radar employs orthogonal or partially correlated transmit signals to achieve performance benefits over its phased-array counterpart. It has been shown that MIMO radar can achieve greater spatial resolution, improved signal-to-noise ratio (SNR) and target localization, and greater clutter resolution using space-time adaptive processing (STAP). This thesis explores various methods to improve the signal-to-interference-plus-noise ratio (SINR) via transmit and receive beamforming. In MIMO radar settings, it is often desirable to transmit power only to a given location or set of locations defined by a beampattern. Current methods involve a two- step process of designing the transmit covariance matrix R via iterative solutions and then using R to generate waveforms that fulfill practical constraints such as having a constant-envelope or drawing from a finite alphabet. In this document, a closed- form method to design R is proposed that utilizes the discrete Fourier transform (DFT) coefficients and Toeplitz matrices. The resulting covariance matrix fulfills the practical constraints such as positive semidefiniteness and the uniform elemental power constraint and provides performance similar to that of iterative methods, which require a much greater computation time. Next, a transmit architecture is presented 
that exploits the orthogonality of frequencies at discrete DFT values to transmit a sum of orthogonal signals from each antenna. The resulting waveforms provide a lower mean-square error than current methods at a much lower computational cost, and a simulated detection scenario demonstrates the performance advantages achieved. It is also desirable to receive signal power only from a given set of directions defined by a beampattern. In a later chapter of this document, the problem of receive beampattern matching is formulated and three solutions to this problem are demonstrated. We show that partitioning the received data vector

  12. A low noise high efficiency buck DC-DC converter with sigma-delta modulation

    Energy Technology Data Exchange (ETDEWEB)

    Cai Shujiang; Pi Changming; Yan Wei; Li Wenhong, E-mail: wenhongli@fudan.edu.cn [State Key Laboratory of ASIC and Systems, Fudan University, Shanghai 201203 (China)

    2011-07-15

    Some research efforts to improve the efficiency and noise performance of buck DC-DC converters are explored. A carefully designed power MOSFET driver, including a dead time controller, discontinuous current mode (DCM) controller and gate width controller, is proposed to improve efficiency. Instead of PWM modulation, sigma-delta modulation is introduced into the feedback loop of the converter to move out the clock-referred harmonic spike. The proposed converter has been designed and fabricated by a 0.35 {mu}m CMOS process. Measured results show that the peak efficiency of the converter can reach 93% and sigma-delta modulation suppresses the harmonic spike by 30 dB over PWM modulation. (semiconductor integrated circuits)

  13. Prediction of high-speed rotor noise with a Kirchhoff formula

    Science.gov (United States)

    Purcell, Timothy W.; Strawn, Roger C.; Yu, Yung H.

    1987-01-01

    A new methodology has been developed to predict the impulsive noise generated by a transonic rotor blade. The formulation uses a full-potential finite-difference method to obtain the pressure field close to the blade. A Kirchhoff integral formulation is then used to extend these finite-difference results into the far-field. This Kirchhoff formula is written in a blade-fixed coordinate system. It requires initial data across a plane at the sonic radius. This data is provided by the finite-difference solution. Acoustic pressure predictions show excellent agreement with hover experimental data for two hover cases of 0.88 and 0.90 tip Mach number, the latter of which has delocalized transonic flow. These results represent the first successful prediction technique for peak pressure amplitudes using a computational code.

  14. Noise from wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Fegeant, Olivier [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Building Sciences

    2002-02-01

    A rapid growth of installed wind power capacity is expected in the next few years. However, the siting of wind turbines on a large scale raises concerns about their environmental impact, notably with respect to noise. To this end, variable speed wind turbines offer a promising solution for applications in densely populated areas like the European countries, as this design would enable an efficient utilisation of the masking effect due to ambient noise. In rural and recreational areas where wind turbines are sited, the ambient noise originates from the action of wind on the vegetation and about the listener's ear (pseudo-noise). It shows a wind speed dependence similar to that of the noise from a variable speed wind turbine and can therefore mask the latter for a wide range of conditions. However, a problem inherent to the design of these machines is their proclivity to pure tone generation, because of the enhanced difficulty of avoiding structural resonances in the mechanical parts. Pure tones are deemed highly annoying and are severely regulated by most noise policies. In relation to this problem, the vibration transmission of structure-borne sound to the tower of the turbine is investigated, in particular when the tower is stiffened at its upper end. Furthermore, since noise annoyance due to wind turbine is mostly a masking issue, the wind-related sources of ambient noise are studied and their masking potentials assessed. With this aim, prediction models for wind-induced vegetation noise and pseudo-noise have been developed. Finally, closely related to the effect of masking, is the difficulty, regularly encountered by local authorities and wind farm developers, to measure noise immission from wind turbines. A new measurement technique has thus been developed in the course of this work. Through improving the signal-to-noise ratio between wind turbine noise and ambient noise, the new technique yields more accurate measurement results.

  15. High-Sensitivity Low-Noise Miniature Fluxgate Magnetometers Using a Flip Chip Conceptual Design

    Directory of Open Access Journals (Sweden)

    Chih-Cheng Lu

    2014-07-01

    Full Text Available This paper presents a novel class of miniature fluxgate magnetometers fabricated on a print circuit board (PCB substrate and electrically connected to each other similar to the current “flip chip” concept in semiconductor package. This sensor is soldered together by reversely flipping a 5 cm × 3 cm PCB substrate to the other identical one which includes dual magnetic cores, planar pick-up coils, and 3-D excitation coils constructed by planar Cu interconnections patterned on PCB substrates. Principles and analysis of the fluxgate sensor are introduced first, and followed by FEA electromagnetic modeling and simulation for the proposed sensor. Comprehensive characteristic experiments of the miniature fluxgate device exhibit favorable results in terms of sensitivity (or “responsivity” for magnetometers and field noise spectrum. The sensor is driven and characterized by employing the improved second-harmonic detection technique that enables linear V-B correlation and responsivity verification. In addition, the double magnitude of responsivity measured under very low frequency (1 Hz magnetic fields is experimentally demonstrated. As a result, the maximum responsivity of 593 V/T occurs at 50 kHz of excitation frequency with the second harmonic wave of excitation; however, the minimum magnetic field noise is found to be 0.05 nT/Hz1/2 at 1 Hz under the same excitation. In comparison with other miniature planar fluxgates published to date, the fluxgate magnetic sensor with flip chip configuration offers advances in both device functionality and fabrication simplicity. More importantly, the novel design can be further extended to a silicon-based micro-fluxgate chip manufactured by emerging CMOS-MEMS technologies, thus enriching its potential range of applications in modern engineering and the consumer electronics market.

  16. Unified Aeroacoustics Analysis for High Speed Turboprop Aerodynamics and Noise. Volume 1; Development of Theory for Blade Loading, Wakes, and Noise

    Science.gov (United States)

    Hanson, D. B.

    1991-01-01

    A unified theory for the aerodynamics and noise of advanced turboprops are presented. Aerodynamic topics include calculation of performance, blade load distribution, and non-uniform wake flow fields. Blade loading can be steady or unsteady due to fixed distortion, counter-rotating wakes, or blade vibration. The aerodynamic theory is based on the pressure potential method and is therefore basically linear. However, nonlinear effects associated with finite axial induction and blade vortex flow are included via approximate methods. Acoustic topics include radiation of noise caused by blade thickness, steady loading (including vortex lift), and unsteady loading. Shielding of the fuselage by its boundary layer and the wing are treated in separate analyses that are compatible but not integrated with the aeroacoustic theory for rotating blades.

  17. 高速列车运行产生的轮轨噪声预测%Prediction of Wheel - rail Noise by Operating High Speed Train

    Institute of Scientific and Technical Information of China (English)

    杨新文; 翟婉明; 和振兴

    2011-01-01

    With the rising of train operation speed, wheel/rail noises are significantly increased. Based on vehicle-track coupled dynamics, random vibration theory and acoustics theory, a model is produced to predict wheel/rail noises by high speed hain operating due to wheel and rail surface roughness, geometric discontinuity in contact, and so on. And the corresponding software WRNOISE (Wheel/Rail Noise)is developed. Compared with existing prediction model TWINS (Track-Wheel Interaction Noise Software), the result shows that the main frequency ranges and trends of the noise of TWINS software simulation values and the present model computation values are consistent. Compared with the model STTIN (Simulation of Train-Track Interaction Noise), the present prediction model can be more fully taken into account the vibration and noise contribution in the axial direction of wheels and the lateral direction of rails. Compared with the noise test values of the high-speed train running on ballasted track and slab track, there are some differences between prediction values of the present model WRNOISE and noise test values, but both trends are in agreement mutually from the viewpoint of wheel-rail noise radiation dominant frequencies.%轮轨噪声随着列车运营速度的提高而显著增大,综合应用车辆-轨道耦合动力学、随机振动理论和声辐射理论,预测由轮轨表面粗糙度、接触不连续几何缺陷等激起的高速列车轮轨噪声,建立轮轨噪声预测模型,并开发相应软件WRNOISE(Wheel/rail Noise).与已有的轮轨噪声预测模型TWINS(Track-Wheel Interaction Noise Software)比较,预测的噪声主频和变化趋势与TWINS的预测结果一致;与STTIN(Simulation ofTrain-TrackInteraction Noise)模型相比,预测模型考虑车轮辐板和钢轨轨腰横向振动噪声的贡献;与有砟和无砟轨道路基区段噪声实测结果的对比表明,WRNOISE模型计算结果与实测结果仍存在一定差异,但

  18. Probing the behaviour of high brightness bunches in collision at 6.5 TeV and the interplay with an external source of noise (MD1433)

    CERN Document Server

    Buffat, Xavier; Furuseth, Sondre Vik; Jacquet, Delphine; Metral, Elias; Pellegrini, Dario; Pojer, Mirko; Trad, Georges; Valuch, Daniel; Barranco Garcia, Javier; Pieloni, Tatiana; Tambasco, Claudia; Li, Qiang; CERN. Geneva. ATS Department

    2017-01-01

    The results of an experiment aiming at colliding high brightness bunches at 6.5 TeV in the LHC and probing the interplay between external noise and head on beam-beam interaction are presented. The colliding bunches are shown to have a burn off dominated lifetime, but they experience a significant emittance growth, possibly resulting from the transverse feedback noise with non standard settings. While several features remain to be understood, the effect of noise on colliding beams seems compatible with the so-called weak-strong model.

  19. Conducted noise analysis and protection of 45 kJ/s, ±50 kV capacitor charging power supply when interfaced with repetitive Marx based pulse power system

    Science.gov (United States)

    Naresh, P.; Patel, Ankur; Sharma, Archana

    2015-09-01

    Pulse power systems with highly dynamic loads like klystron, backward wave oscillator (BWO), and magnetron generate highly dynamic noise. This noise leads to frequent failure of controlled switches in the inverter stage of charging power supply. Designing a reliable and compatible power supply for pulse power applications is always a tricky job when charging rate is in multiples of 10 kJ/s. A ±50 kV and 45 kJ/s capacitor charging power supply based on 4th order LCLC resonant topology has been developed for a 10 Hz repetitive Marx based system. Conditions for load independent constant current and zero current switching (ZCS) are derived mathematically. Noise generated at load end due to dynamic load is tackled effectively and reduction in magnitude noise voltage is achieved by providing shielding between primary and secondary of high voltage high frequency transformer and with LCLC low pass filter. Shielding scales down the ratio between coupling capacitance (Cc) and the collector-emitter capacitance of insulated gate bi-polar transistor switch, which in turn reduces the common mode noise voltage magnitude. The proposed 4th order LCLC resonant network acts as a low pass filter for differential mode noise in the reverse direction (from load to source). Power supply has been tested repeatedly with 5 Hz repetition rate with repetitive Marx based system connected with BWO load working fine without failure of single switch in the inverter stage.

  20. Low-Noise Free-Running High-Rate Photon-Counting for Space Communication and Ranging

    Science.gov (United States)

    Lu, Wei; Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Merritt, Scott

    2016-01-01

    We present performance data for low-noise free-running high-rate photon counting method for space optical communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (50) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their performances using both the 2 detected photon threshold and coincidence methods.

  1. Noise-immune cavity-enhanced optical frequency comb spectroscopy: A sensitive technique for high-resolution broadband molecular detection

    CERN Document Server

    Khodabakhsh, Amir; Foltynowicz, Aleksandra

    2014-01-01

    Noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS) is a recently developed technique that utilizes phase modulation to obtain immunity to frequency-to-amplitude noise conversion by the cavity modes and yields high absorption sensitivity over a broad spectral range. We describe the principles of the technique and discuss possible comb-cavity matching solutions. We present a theoretical description of NICE-OFCS signals detected with a Fourier transform spectrometer (FTS), and validate the model by comparing it to experimental CO2 spectra around 1575 nm. Our system is based on an Er:fiber femtosecond laser locked to a cavity and phase-modulated at a frequency equal to a multiple of the cavity free spectral range (FSR). The NICE-OFCS signal is detected by a fast-scanning FTS equipped with a high-bandwidth commercial detector. We demonstrate a simple method of passive locking of the modulation frequency to the cavity FSR that significantly improves the long term stability of the system, a...

  2. Unified aeroacoustics analysis for high speed turboprop aerodynamics and noise. Volume 3: Application of theory for blade loading, wakes, noise, and wing shielding

    Science.gov (United States)

    Hanson, D. B.; Mccolgan, C. J.; Ladden, R. M.; Klatte, R. J.

    1991-01-01

    Results of the program for the generation of a computer prediction code for noise of advanced single rotation, turboprops (prop-fans) such as the SR3 model are presented. The code is based on a linearized theory developed at Hamilton Standard in which aerodynamics and acoustics are treated as a unified process. Both steady and unsteady blade loading are treated. Capabilities include prediction of steady airload distributions and associated aerodynamic performance, unsteady blade pressure response to gust interaction or blade vibration, noise fields associated with thickness and steady and unsteady loading, and wake velocity fields associated with steady loading. The code was developed on the Hamilton Standard IBM computer and has now been installed on the Cray XMP at NASA-Lewis. The work had its genesis in the frequency domain acoustic theory developed at Hamilton Standard in the late 1970s. It was found that the method used for near field noise predictions could be adapted as a lifting surface theory for aerodynamic work via the pressure potential technique that was used for both wings and ducted turbomachinery. In the first realization of the theory for propellers, the blade loading was represented in a quasi-vortex lattice form. This was upgraded to true lifting surface loading. Originally, it was believed that a purely linear approach for both aerodynamics and noise would be adequate. However, two sources of nonlinearity in the steady aerodynamics became apparent and were found to be a significant factor at takeoff conditions. The first is related to the fact that the steady axial induced velocity may be of the same order of magnitude as the flight speed and the second is the formation of leading edge vortices which increases lift and redistribute loading. Discovery and properties of prop-fan leading edge vortices were reported in two papers. The Unified AeroAcoustic Program (UAAP) capabilites are demonstrated and the theory verified by comparison with the

  3. A high-speed low-noise transimpedance amplifier in a 025 mum CMOS technology

    CERN Document Server

    Anelli, G; Casagrande, L; Despeisse, Matthieu; Jarron, Pierre; Pelloux, Nicolas; Saramad, Shahyar

    2003-01-01

    We present the simulated and measured performance of a transimpedance amplifier designed in a quarter micron CMOS process. Containing only NMOS and PMOS devices, this amplifier can be integrated in any submicron CMOS process. The main feature of this design is the use of a transistor in the feedback path instead of a resistor. The circuit has been optimized for reading signals coming from silicon strip detectors with few pF input capacitance. For an input charge of 4fC, an input capacitance of 4pF and a transresistance of 135kOmega, we have measured an output pulse fall time of 3ns and an Equivalent Noise Charge (ENC) of around 350 electrons rms. In view of the operation of the chip at cryogenic temperatures, measurements at 130K have also been carried out, showing an overall improvement in the performance of the chip. Fall times down to 1.5ns have been measured. An integrated circuit containing 32 channels has been designed and wire bonded to a silicon strip detector and successfully used for the constructio...

  4. Beyond noise: using temporal ICA to extract meaningful information from high-frequency fMRI signal fluctuations during rest

    Directory of Open Access Journals (Sweden)

    Roland Norbert Boubela

    2013-05-01

    Full Text Available Analysis of resting-state networks using fMRI usually ignores high-frequencyfluctuations in the BOLD signal – be it because of low TR prohibiting the analysis offluctuations with frequencies higher than 0.25 Hz (for a typical TR of 2 s, or becauseof the application of a bandpass filter (commonly restricting the signal to frequencieslower than 0.1 Hz. While the standard model of convolving neuronal activity with ahemodynamic response function suggests that the signal of interest in fMRI is characterized by slow fluctuation, it is in fact unclear whether the high-frequency dynamics of the signal consists of noise only. In this study, 10 subjects were scanned at 3 T during 6 minutes of rest using a multiband EPI sequence with a TR of 354 ms to critically sample fluctuations of up to 1.4 Hz. Preprocessed data were high-pass filtered to include only frequencies above 0.25 Hz, and voxelwise whole-brain temporal ICA (tICA was used to identify consistent high-frequency signals. The resulting components include physiological background signal sources, most notably pulsation and heartbeat components, that can be specifically identified and localized with the method presented here. Perhaps more surprisingly, common resting-state networks like the default-mode network also emerge as separate tICA components. This means that high frequency oscillations sampled with a rather T1-weighted contrast still contain specific information on these resting-state networks to consistently identify them, not consistent with the commonly held view that these networks operate on low-frequency fluctuations alone. Consequently, the use of bandpass filters in resting-state data analysis should be reconsidered, since this step eliminates potentially relevant information. Instead, more specific methods for the elimination of physiological background signals, for example by regression of physiological noise components, might prove to be viable alternatives.

  5. Review of active noise control technology in high speed train%高速列车车厢内噪声主动控制技术综述

    Institute of Scientific and Technical Information of China (English)

    靳光磊; 刘永明

    2011-01-01

    传统的高速列车噪声控制多采用隔音、减振等被动的降噪方法,仅对中高频噪声的控制有效,无法满足时速300 km以上高速列车的噪声控制要求.而主动噪声控制技术通过有目的地产生一个次级声信号来消弭低频噪声,适于高速列车车厢内噪声控制.无论次级声源控制还是次级力源控制,都要增强系统的可靠性和鲁棒性,而宽带噪声控制的多通道自适应噪声主动控制技术将会成为该领域的研究热点.%The traditional method of high-speed train noise control use passive noise reduction methods, such as sound insulation,vibration reduction and so on,but only the high-frequency noise control effective, which can't meet the requirements of more than 300 km/h high-speed train noise control. In order to eliminate low-frequency noise purposely, the active noise control for high-speed trains generate the secondary acoustic signal. Whether the secondary sound source control or secondary force source of control,the noise control methods should enhance system reliability and robustness, and the broadband multi-channel adaptive active noise control technology will become the research focus.

  6. Centimeter-deep tissue fluorescence microscopic imaging with high signal-to-noise ratio and picomole sensitivity

    CERN Document Server

    Cheng, Bingbing; Wei, Ming-Yuan; Pei, Yanbo; DSouza, Francis; Nguyen, Kytai T; Hong, Yi; Tang, Liping; Yuan, Baohong

    2015-01-01

    Fluorescence microscopic imaging in centimeter-deep tissue has been highly sought-after for many years because much interesting in vivo micro-information, such as microcirculation, tumor angiogenesis, and metastasis, may deeply locate in tissue. In this study, for the first time this goal has been achieved in 3-centimeter deep tissue with high signal-to-noise ratio (SNR) and picomole sensitivity under radiation safety thresholds. These results are demonstrated not only in tissue-mimic phantoms but also in actual tissues, such as porcine muscle, ex vivo mouse liver, ex vivo spleen, and in vivo mouse tissue. These results are achieved based on three unique technologies: excellent near infrared ultrasound-switchable fluorescence (USF) contrast agents, a sensitive USF imaging system, and an effective correlation method. Multiplex USF fluorescence imaging is also achieved. It is useful to simultaneously image multiple targets and observe their interactions. This work opens the door for future studies of centimeter...

  7. 'Modal-noise' in single-mode fibers: A cautionary note for high precision radial velocity instruments

    CERN Document Server

    Halverson, Samuel; Mahadevan, Suvrath; Schwab, Christian

    2015-01-01

    Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical 'seeing-limited' instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as 'modal noise', are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, these fibers do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading il...

  8. A low noise, high thermal stability, 0.1 K test facility for the Planck HFI bolometers

    Science.gov (United States)

    Paine, C. G.; Bock, J. J.; Hristov, V. V.; Lange, A. E.

    2002-05-01

    We are developing a facility which will be used to characterize the bolometric detectors for Planck, an ESA mission to investigate the Cosmic Microwave Background. The bolometers operate at 0.1 K, employing neutron-transmutation doped (NTD) Ge thermistors with resistances of several megohms to achieve NEPs˜1×10-17 W Hz-1/2. Characterization of the intrinsic noise of the bolometers at frequencies as low as 0.010 Hz dictates a test apparatus thermal stability of 40 nK Hz-1/2 to that frequency. This temperature stability is achieved via a multi-stage isolation and control geometry with high resolution thermometry implemented with NTD Ge thermistors, JFET source followers, and dedicated lock-in amplifiers. The test facility accommodates 24 channels of differential signal readout, for measurement of bolometer V(I) characteristics and intrinsic noise. The test facility also provides for modulated radiation in the submillimeter band incident on the bolometers, for measurement of the optical speed-of-response; this illumination can be reduced below detectable limits without interrupting cryogenic operation. A commercial Oxford Instruments dilution refrigerator provides the cryogenic environment for the test facility.

  9. Experimental investigation of high energy noise-like pulses from a long cavity erbium-doped fiber laser

    Science.gov (United States)

    Li, Kexuan; Guoyu, Heyang; Tian, Jinrong; Song, Yanrong

    2016-11-01

    The high energy noise-like pulses (NLPs) were experimentally investigated in a passively mode-locked erbium-doped fiber laser with a long ring cavity by using nonlinear polarization rotation technique. Large net normal group-velocity dispersion of the cavity is estimated as high as 6.46 ps2, which is beneficial to formation of high-energy pulses. With the total pump power of 970 mW (the pump powers of forward pump and backward pump are set at the value of 455 mW and 515 mW, respectively), a stable ultrahigh energy rectangular-shape pulse emission with the pulse duration of 35 ns was observed. The energy of square packet with a fundamental repetition rate of 141.6 kHz is as high as 840 nJ. The signal-to-noise is higher than 60 dB in RF spectrum. The feature of NLPs is confirmed by the coherent spike of autocorrelation trace. When the pump power is beyond 970 mW, the mode locking operation with fundamental repetition rate cannot be achieved despite of the large range variation of polarization controller (PC) settings. However, the forthorder harmonic mode locking can be observed, the square pulse packet duration still remains at ˜ 35 ns. The experimental results demonstrated that the ultrahigh energy NLPs is only realized at the condition of special physical parameters and it is restricted by the number and intensity of ultra short pulses within the envelope to some extent.

  10. Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To meet the demands of future high-capacity free space optical communications links, a high bandwidth, near infrared (NIR), single photon sensitive optoelectronic...

  11. Influence of wheel polygonal wear on interior noise of high-speed trains%高速列车车轮多边形对车内噪声的影响

    Institute of Scientific and Technical Information of China (English)

    Jie ZHANG; Guang-xu HAN; Xin-biao XIAO; Rui-qian WANG; Yue ZHAO; Xue-song JIN

    2014-01-01

    This work presents a detailed investigation conducted into the relationships between wheel polygonal wear and wheel/rail noise, and the interior noise of high-speed trains through extensive experiments and numerical simulations. The field experiments include roundness measurement and characteristics analysis of the high-speed wheels in service, and analysis on the effect of re-profiling on the interior noise of the high-speed coach. The experimental analysis shows that wheel polygonal wear has a great impact on wheel/rail noise and interior noise. In the numerical simulation, the model of high-speed wheel/rail noise caused by the uneven wheel wear is developed by means of the high-speed wheel-track noise software (HWTNS). The calculation model of the interior noise of a high-speed coach is developed based on the hybrid of the finite element method and the statistic energy analysis (FE-SEA). The numerical simulation analyses the effect of the polygonal wear characteristics, such as roughness level, polygon order (or wavelength), and polygon phase, on wheel/rail noise and interior noise of a high-speed coach. The numerical results show that different polygon order with nearly the same roughness levels can cause different wheel/rail noises and interior noises. The polygon with a higher roughness level can cause a larger wheel/rail noise and a larger interior noise. The combination of different polygon phases can make a different wheel circle diameter difference due to wear, but its effect on the interior noise level is not great. This study can provide a basis for improving the criteria for high-speed wheel re-profiling of China’s high-speed trains.

  12. Influence of inductance induced noise in an YBa2Cu3O7 dc-SQUID at high operation temperatures

    DEFF Research Database (Denmark)

    Nilsson, P. Å.; Claeson, T.; Hansen, J. B.;

    1994-01-01

    The voltage modulation depth of a high T(c) dc-SQUID was measured at temperatures close to T(c) and compared to a model by Enpuku et al. where the flux noise from the SQUID inductance is taken into account. The device was an YBa2Cu3O7 dc-SQUID made on a bicrystal substrate of SrTiO3. The design...... was of the Ketchen square-washer type with an inductance of 67 pH. Measurements were made in a temperature interval from 75 to 87 K, where the voltage modulation depth changed from 4.5 to 1.4 muV in close agreement with the model....

  13. Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flights Conditions

    Science.gov (United States)

    Elliott, David M.; Woodward, Richard P.; Podboy, Gary G.

    2010-01-01

    Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept.

  14. Low noise high-Tc superconducting bolometers on silicon nitride membranes for far-infrared detection

    NARCIS (Netherlands)

    Nivelle, de M.J.M.E.; Bruijn, M.P.; Vries, de R.; Wijnbergen, J.J.; Korte, de P.A.J.; Sanchez, S.; Elwenspoek, M.; Heidenblut, T.; Schwierzi, B.; Michalke, W.; Steinbeiss, E.

    1997-01-01

    High-Tc GdBa2Cu3O7 – delta superconductor bolometers with operation temperatures near 89 K, large receiving areas of 0.95 mm2 and very high detectivity have been made. The bolometers are supported by 0.62 µm thick silicon nitride membranes. A specially developed silicon-on-nitride layer was used to

  15. Synthesis of multi-wavelength temporal phase-shifting algorithms optimized for high signal-to-noise ratio and high detuning robustness using the frequency transfer function

    CERN Document Server

    Servin, Manuel; Garnica, Guillermo

    2016-01-01

    Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for interferometry is well-known and firmly based on the frequency transfer function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors are present. The FTF-based synthesis for dual-wavelength PSA (DW-PSA) is optimized for high signal-to-noise ratio and minimum number of temporal phase-shifted interferograms. The DW-PSA synthesis herein presented may be used for interferometric contouring of discontinuous industrial objects. Also DW-PSA may be useful for DW shop-testing of deep free-form aspheres. As shown here, using the FTF-based synthesis one may easily find explicit DW-PSA formulae optimized for high signal-to-noise and high detuning robustness. To this date, no general synthesis and analysis for temporal DW-PSAs has been given; only had-hoc DW-PSAs formulas have been reported. Consequently, no explicit formulae for their spectra, their sign...

  16. Neuropathic pain: transcranial electric motor cortex stimulation using high frequency random noise. Case report of a novel treatment

    Directory of Open Access Journals (Sweden)

    Alm PA

    2013-06-01

    Full Text Available Per A Alm, Karolina DreimanisDepartment of Neuroscience, Uppsala University, Uppsala, SwedenObjectives: Electric motor cortex stimulation has been reported to be effective for many cases of neuropathic pain, in the form of epidural stimulation or transcranial direct current stimulation (tDCS. A novel technique is transcranial random noise stimulation (tRNS, which increases the cortical excitability irrespective of the orientation of the current. The aim of this study was to investigate the effect of tRNS on neuropathic pain in a small number of subjects, and in a case study explore the effects of different stimulation parameters and the long-term stability of treatment effects.Methods: The study was divided into three phases: (1 a double-blind 100–600 Hz, varying from 0.5 to 10 minutes and from 50 to 1500 µA, at intervals ranging from daily to fortnightly.crossover study, with four subjects; (2 a double-blind extended case study with one responder; and (3 open continued treatment. The motor cortex stimulation consisted of alternating current random noise (100–600 Hz, varying from 0.5 to 10 minutes and from 50 to 1500 μA, at intervals ranging from daily to fortnightly.Results: One out of four participants showed a strong positive effect (also compared with direct-current-sham, P = 0.006. Unexpectedly, this effect was shown to occur also for very weak (100 µA, P = 0.048 and brief (0.5 minutes, P = 0.028 stimulation. The effect was largest during the first month, but remained at a highly motivating level for the patient after 6 months.Discussion: The study suggests that tRNS may be an effective treatment for some cases of neuropathic pain. An important result was the indication that even low levels of stimulation may have substantial effects.Keywords: neuropathic pain, central pain, transcranial direct current stimulation, motor cortex stimulation, random noise stimulation

  17. Low Frequency Noise Degradation in 45 nm High-k nMOSFETs due to Hot Carrier and Constant Voltage Stress

    Science.gov (United States)

    Rahman, M. Shahriar; ćelik-Butler, Zeynep; Quevedo-Lopez, M. A.; Shanware, Ajit; Colombo, Luigi

    2009-04-01

    Hafnium based materials are the leading candidates to replace conventional SiON as the gate dielectric in complementary metal-oxide-semiconductor devices. Hot carrier and constant voltage stress induced 1/f noise behavior is presented for HfSiON nMOSFETs. The additional low-frequency noise introduced through stressing was evaluated on nMOSFETs with TiN metal gate and HfSiON gate dielectric. Nitridation of HfSiO was achieved either by high temperature thermal nitridation or by relatively lower temperature plasma nitridation. The difference in stress induced noise behavior is attributed to the nitrogen profile across high-k/Si interface and bulk of high-k gate oxide caused by different nitridation techniques.

  18. A study on the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise

    Directory of Open Access Journals (Sweden)

    Yukio Takahashi

    2011-01-01

    Full Text Available To investigate the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise, we conducted two experiments. In Experiment 1, eight male subjects were exposed to seven types of low-frequency noise stimuli: two pure tones [a 31.5-Hz, 100-dB(SPL tone and a 50-Hz, 100-dB(SPL tone] and five complex noises composed of the pure tones. For the complex noise stimuli, the sound pressure level of one tonal component was 100 dB(SPL and that of another one was either 90, 95, or 100 dB(SPL. Vibration induced on the body surface was measured at five locations, and the correlation with the subjective rating of the vibratory sensation at each site of measurement was examined. In Experiment 2, the correlation between the body surface vibration and the vibratory sensation was similarly examined using seven types of noise stimuli composed of a 25-Hz tone and a 50-Hz tone. In both the experiments, we found that at the chest and the abdomen, the rating of the vibratory sensation was in close correlation with the vibration acceleration level (VAL of the body surface vibration measured at each corresponding location. This was consistent with our previous results and suggested that at the trunk of the body (the chest and the abdomen, the mechanoreception of body vibrations plays an important role in the experience of the vibratory sensation in persons exposed to high-level low-frequency noise. At the head, however, no close correlation was found between the rating of the vibratory sensation and the VAL of body surface vibration. This suggested that at the head, the perceptual mechanisms of vibration induced by high-level low-frequency noise were different from those in the trunk of the body.

  19. High resolution 1H NMR-based metabonomic study of the auditory cortex analogue of developing chick (Gallus gallus domesticus) following prenatal chronic loud music and noise exposure.

    Science.gov (United States)

    Kumar, Vivek; Nag, Tapas Chandra; Sharma, Uma; Mewar, Sujeet; Jagannathan, Naranamangalam R; Wadhwa, Shashi

    2014-10-01

    Proper functional development of the auditory cortex (ACx) critically depends on early relevant sensory experiences. Exposure to high intensity noise (industrial/traffic) and music, a current public health concern, may disrupt the proper development of the ACx and associated behavior. The biochemical mechanisms associated with such activity dependent changes during development are poorly understood. Here we report the effects of prenatal chronic (last 10 days of incubation), 110dB sound pressure level (SPL) music and noise exposure on metabolic profile of the auditory cortex analogue/field L (AuL) in domestic chicks. Perchloric acid extracts of AuL of post hatch day 1 chicks from control, music and noise groups were subjected to high resolution (700MHz) (1)H NMR spectroscopy. Multivariate regression analysis of the concentration data of 18 metabolites revealed a significant class separation between control and loud sound exposed groups, indicating a metabolic perturbation. Comparison of absolute concentration of metabolites showed that overstimulation with loud sound, independent of spectral characteristics (music or noise) led to extensive usage of major energy metabolites, e.g., glucose, β-hydroxybutyrate and ATP. On the other hand, high glutamine levels and sustained levels of neuromodulators and alternate energy sources, e.g., creatine, ascorbate and lactate indicated a systems restorative measure in a condition of neuronal hyperactivity. At the same time, decreased aspartate and taurine levels in the noise group suggested a differential impact of prenatal chronic loud noise over music exposure. Thus prenatal exposure to loud sound especially noise alters the metabolic activity in the AuL which in turn can affect the functional development and later auditory associated behaviour.

  20. Inhibitory noise

    Directory of Open Access Journals (Sweden)

    Alain Destexhe

    2010-03-01

    Full Text Available Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron's input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory noise. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.

  1. Dissecting the frog inner ear with Gaussian noise .1. Application of high-order Wiener-kernel analysis

    NARCIS (Netherlands)

    vanDijk, P; Wit, HP; Segenhout, JM

    1997-01-01

    Wiener kernel analysis was used to characterize the auditory pathway from tympanic membrane to single primary auditory nerve fibers in the European edible frog, Rana esculenta. Nerve fiber signals were recorded in response to white Gaussian noise. By cross-correlating the noise stimulus and the nerv

  2. The free energy cost of reducing noise while maintaining a high sensitivity

    Science.gov (United States)

    Sartori, Pablo; Tu, Yuhai

    2016-01-01

    Living systems need to be highly responsive, and also to keep fluctuations low. These goals are incompatible in equilibrium systems due to the Fluctuation Dissipation Theorem (FDT). Here, we show that biological sensory systems, driven far from equilibrium by free energy consumption, can reduce their intrinsic fluctuations while maintaining high responsiveness. By developing a continuum theory of the E. coli chemotaxis pathway, we demonstrate that adaptation can be understood as a non-equilibrium phase transition controlled by free energy dissipation, and it is characterized by a breaking of the FDT. We show that the maximum response at short time is enhanced by free energy dissipation. At the same time, the low frequency fluctuations and the adaptation error decrease with the free energy dissipation algebraically and exponentially, respectively. PMID:26406857

  3. The free energy cost of reducing noise while maintaining a high sensitivity

    CERN Document Server

    Sartori, Pablo

    2015-01-01

    Living systems need to be highly responsive, and also to keep fluctuations low. These goals are incompatible in equilibrium systems due to the Fluctuation Dissipation Theorem (FDT). Here, we show that biological sensory systems, driven far from equilibrium by free energy consumption, can reduce their intrinsic fluctuations while maintaining high responsiveness. By developing a continuum theory of the E. coli chemotaxis pathway, we demonstrate that adaptation can be understood as a non-equilibrium phase transition controlled by free energy dissipation, and it is characterized by a breaking of the FDT. We show that the maximum response at short time is enhanced by free energy dissipation. At the same time, the low frequency fluctuations and the adaptation error decrease with the free energy dissipation algebraically and exponentially, respectively.

  4. High signal-to-noise ratio observations and the ultimate limits of precision pulsar timing

    CERN Document Server

    Oslowski, Stefan; Hobbs, George; Bailes, Matthew; Demorest, Paul

    2011-01-01

    We demonstrate that the sensitivity of high-precision pulsar timing experiments will be ultimately limited by the broadband intensity modulation that is intrinsic to the pulsar's stochastic radio signal. That is, as the peak flux of the pulsar approaches that of the system equivalent flux density, neither greater antenna gain nor increased instrumental bandwidth will improve timing precision. These conclusions proceed from an analysis of the covariance matrix used to characterise residual pulse profile fluctuations following the template matching procedure for arrival time estimation. We perform such an analysis on 25 hours of high-precision timing observations of the closest and brightest millisecond pulsar, PSR J0437-4715. In these data, the standard deviation of the post-fit arrival time residuals is approximately four times greater than that predicted by considering the system equivalent flux density, mean pulsar flux and the effective width of the pulsed emission. We develop a technique based on principa...

  5. Ultra High Bypass Ratio Engine Research for Reducing Noise, Emissions, and Fuel Consumption

    Science.gov (United States)

    Hughes, Christopher E.; Schweitzer, Jeff

    2007-01-01

    A pictorial history of NASA development of advanced engine technologies for reducing environmental emissions and increasing performance from the 1970s to 2000s is presented. The goals of the Subsonic Fixed Wing Program portion of the NASA Fundamental Aeronautics Program are discussed, along with the areas of investigation currently being pursued by the Ultra High Bypass Partnership Element of the Subsonic Fixed Wing Program.

  6. Estimation of (near) low-rank matrices with noise and high-dimensional scaling

    CERN Document Server

    Negahban, Sahand

    2009-01-01

    High-dimensional inference refers to problems of statistical estimation in which the ambient dimension of the data may be comparable to or possibly even larger than the sample size. We study an instance of high-dimensional inference in which the goal is to estimate a matrix $\\Theta^* \\in \\real^{k \\times p}$ on the basis of $N$ noisy observations, and the unknown matrix $\\Theta^*$ is assumed to be either exactly low rank, or ``near'' low-rank, meaning that it can be well-approximated by a matrix with low rank. We consider an $M$-estimator based on regularization by the trace or nuclear norm over matrices, and analyze its performance under high-dimensional scaling. We provide non-asymptotic bounds on the Frobenius norm error that hold for a general class of noisy observation models, and then illustrate their consequences for a number of specific matrix models, including low-rank multivariate or multi-task regression, system identification in vector autoregressive processes, and recovery of low-rank matrices fro...

  7. Noise sources and noise suppression in CMOS imagers

    Science.gov (United States)

    Pain, Bedabrata; Cunningham, Thomas J.; Hancock, Bruce R.

    2004-01-01

    Mechanisms for noise coupling in CMOS imagers are complex, since unlike a CCD, a CMOS imager has to be considered as a full digital-system-on-a-chip, with a highly sensitive front-end. In this paper, we analyze the noise sources in a photodiode CMOS imager, and model their propagation through the signal chain to determine the nature and magnitude of noise coupling. We present methods for reduction of noise, and present measured data to show their viability. For temporal read noise reduction, we present pixel signal chain design techniques to achieve near 2 electrons read noise. We model the front-end reset noise both for conventional photodiode and CTIA type of pixels. For the suppression of reset noise, we present a column feedback-reset method to reduce reset noise below 6 electrons. For spatial noise reduction, we present the design of column signal chain that suppresses both spatial noise and power supply coupling noise. We conclude by identifying problems in low-noise design caused by dark current spatial distribution.

  8. Analysis on Common Mode Current of Single-Phase Grid-Connected PV System%单相光伏并网系统共模电流分析

    Institute of Scientific and Technical Information of China (English)

    杨秋霞; 高金玲; 荣雅君; 任玉艳

    2011-01-01

    Common mode current problem is very important to grid-connected photovoltaic (PV) system and in German standard DIN VDE 0126-1-1, the stipulations related to the common mode current are specified. When common mode current exceeds specified value, the connected PV generation system should be cut off within the stipulated time.Considering the importance of common mode current to the connection of photovoltaic generation to power grid, a common mode current is built. It is known throuth the analysis that common mode current is related to modulation technology and the position where the inductance locates. In allusion to above-mentioned features, a new single-phase grid-connected PV system that can suppress common mode current is designed.The designed system is a full-bridge single-phase gridconnected PV system with AC bypass circuit and in which inductances are symmetically arranged at both phase line and neutral line. Comparing with traditional full-bridge inverter systems adopting unipolar or bi-polar modulation technology,the structure of the proposed single-phase grid-connected PV system not only can eliminate common mode current produced in the grid-connected PV system, but also improve system efficiency and quality of current sent into power grid, thus the overall performance of the grid-connected PV system is improved. Results from theoretical analysis and simulation show that the proposed model and system are correct and available.%共模电流问题是光伏并网系统中的一个重要问题,德国DIN VDE 0126-1-1对共模电流做出了相关规定.当共模电流超过规定值时,系统必须在规定的时间内断开.考虑到共模电流在光伏并网系统中的重要性,建立了共模模型.通过分析可知,共模电流与调制技术和电感的安放位置相关.针对上述特点,设计了能够抑制共模电流的新型单相光伏并网系统,即带有交流旁路且电感对称分布在相线和中线上的全桥光伏并网系统.与传

  9. A review of crustacean sensitivity to high amplitude underwater noise: Data needs for effective risk assessment in relation to UK commercial species.

    Science.gov (United States)

    Edmonds, Nathan J; Firmin, Christopher J; Goldsmith, Denise; Faulkner, Rebecca C; Wood, Daniel T

    2016-07-15

    High amplitude anthropogenic noise is associated with adverse impacts among a variety of organisms but detailed species-specific knowledge is lacking in relation to effects upon crustaceans. Brown crab (Cancer pagurus), European lobster (Homarus gammarus) and Norway lobster (Nephrops norvegicus) together represent the most valuable commercial fishery in the UK (Defra, 2014). Critical evaluation of literature reveals physiological sensitivity to underwater noise among N. norvegicus and closely related crustacean species, including juvenile stages. Current evidence supports physiological sensitivity to local, particle motion effects of sound production in particular. Derivation of correlative relationships between the introduction of high amplitude impulsive noise and crustacean distribution/abundance is hindered by the coarse resolution of available data at the present time. Future priorities for research are identified and argument for enhanced monitoring under current legislative frameworks outlined. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  10. Very high-gain and low-excess noise near-infrared single-photon avalanche detector: an NIR solid state photomultiplier

    Science.gov (United States)

    Linga, Krishna; Yevtukhov, Yuriy; Liang, Bing

    2009-05-01

    A new family of photodetectors with a Discrete Amplification (DA) mechanism allows the realization of very high gain and low excess noise factor in the visible and near infrared spectral regions and offers an alternative to conventional photomultiplier tubes and Geiger mode avalanche photodetectors. These photodetectors can operate in linear detection mode with gain-bandwidth product in excess of 4X1014 and in photon counting mode with count rates up to 108 counts/sec. Potential benefits of this technology over conventional avalanche photodetectors include ultra low excess noise factor, very high gain, and lower reset time (photodetectors in the near infrared wavelength range. The measured devices have the following performance characteristics: gain > 2X105, excess noise factor Lidar, quantum cryptography, night vision and other military, defence and aerospace applications.

  11. Observation of phase noise reduction in photonically synthesized sub-THz signals using a passively mode-locked laser diode and highly selective optical filtering

    DEFF Research Database (Denmark)

    Criado, A. R.; Acedo, P.; Carpintero, G.

    2012-01-01

    A Continuous Wave (CW) sub-THz photonic synthesis setup based on a single Passively Mode-Locked Laser Diode (PMLLD) acting as a monolithic Optical Frequency Comb Generator (OFCG) and highly selective optical filtering has been implemented to evaluate the phase noise performance of the generated sub......-THz signals. The analysis of the synthesized sub-THz signals up to 120 GHz gives as a result an effective reduction of the electrical linewidth when compared to direct harmonic generation that begins at 50 GHz and becomes greater as the frequency increases. The phase noise reduction offered by the setup......, along with its integration potential, cost and bandwidth, make it a promising candidate to the development of an integrated and high performance low phase noise local oscillator in the sub-THz range....

  12. Amplifier removes common-mode noise on RGB differential-video-transmission line%能消除RGB差分视频传输线上共模噪声的放大器

    Institute of Scientific and Technical Information of China (English)

    Tamara Papalias; Mike Wong

    2006-01-01

    5类网络电缆由四对双绞线组成.并有耐用的外套.这种电缆能为分量视频信号的传输提供一种通用而有良好性价比的选择。三个线对可以承载RGB视频信号.而第四对线可以承载音频信号、同步信号和其它传输信号。不幸的是.5类电缆缺乏屏蔽.因此容易遭受共模噪声耦合干扰.共模噪声会在每根电缆导体上产生相等的电压。针对共模问题的第一个防护方法是将RGB信号配置成差分电压.但双绞线的驱动器与接收器的两个地基准之间的任何电压差都会在每根接收线上产生一个共模信号。

  13. Influence Factors of Audible Noise Caused by Corona Discharge on UHVDC Transmission Lines Under High Altitude Condition

    Institute of Scientific and Technical Information of China (English)

    TIAN Feng; YU Zhanqing; ZENG Rong; LIU Lei; LI Min; LI Ruihai

    2012-01-01

    Audible noises (AN) generated by corona discharges on ultra high voltage direct current (UHVDC) transmission lines is one of the key issues of UHVDC power projects. Experimental results were obtained synchronously by 10 Briiel & Kjeer outdoor AN instruments under the full-scale test lines in National Laboratory for UHV Technology in Kunming at an altitude of 2 100 m. Long-term statistical measurements of the AN level were performed almost 24 hours a day and 5 ~ 6 days a week in 2 years. Influences of voltage, line configurations, temperature and humidity on the characteristics of AN levels were analysed. The measurement results show that the AN level rises with increasing line voltage, decreasing minimum conductor height and increasing bundle radius. The pole spacing has no significant influence on the peak value of the AN level. The AN level varies about _+ 1 dB in the temperature range of 15~22℃, and no more than ±2 dB within 6.8~24.4 ℃. The results also indicate that in a relative low range of absolute humidity, about 5 ~ 7. 99 g/ma, the AN level fluctuates slightly at different measurement points. However, in a relative high absolute humidity range, about 8 ~ 11. 5 g/ma, the AN level decreases with the increase of absolute humidity.

  14. Optical noise-free image encryption based on quick response code and high dimension chaotic system in gyrator transform domain

    Science.gov (United States)

    Sui, Liansheng; Xu, Minjie; Tian, Ailing

    2017-04-01

    A novel optical image encryption scheme is proposed based on quick response code and high dimension chaotic system, where only the intensity distribution of encoded information is recorded as ciphertext. Initially, the quick response code is engendered from the plain image and placed in the input plane of the double random phase encoding architecture. Then, the code is encrypted to the ciphertext with noise-like distribution by using two cascaded gyrator transforms. In the process of encryption, the parameters such as rotation angles and random phase masks are generated as interim variables and functions based on Chen system. A new phase retrieval algorithm is designed to reconstruct the initial quick response code in the process of decryption, in which a priori information such as three position detection patterns is used as the support constraint. The original image can be obtained without any energy loss by scanning the decrypted code with mobile devices. The ciphertext image is the real-valued function which is more convenient for storing and transmitting. Meanwhile, the security of the proposed scheme is enhanced greatly due to high sensitivity of initial values of Chen system. Extensive cryptanalysis and simulation have performed to demonstrate the feasibility and effectiveness of the proposed scheme.

  15. Noise of a model high speed counterrotation propeller at simulated takeoff/approach conditions (F7/A7)

    Science.gov (United States)

    Woodward, Richard P.

    1987-01-01

    A high speed advanced counterrotation propeller, was tested in the NASA-Lewis 9 x 15 foot Anechoic Wind Tunnel at simulated takeoff/approach conditions of 0.2 Mach number. Acoustic measurements were taken with fixed floor microphones, an axially translating microphone probe, and with a polar microphone probe which was fixed to the propeller nacelle and could take both sideline and circumferential acoustic surveys. Aerodynamic measurements were also made to establish the propeller operating conditions. The propeller was run over a range of blade setting angles from 36.4/36.5 to 41.1/39.4 deg, tip speeds from 165 to 259 m/sec, rotor spacings from 1.56 to 3.63 based on forward rotor tip chord to aerodynamic separation, and angles of attack to + or - 16 deg. First order rotor alone tones showed highest directivity levels near the propeller plane, while interaction tone showed high levels throughout sideline directivity, especially toward the propeller rotation axis. Interaction tone levels were sensitive to propeller row spacing while rotor alone tones showed little spacing effect. There is a decreased noise level associated with higher propeller blade numbers for the same overall propeller thrust.

  16. Functionalized Nano-Film Microchannel Plate: A Single High Aspect Ratio Device for High Resolution, Low Noise Astronomical Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Atomic layer deposited functional nano-film technology is used to manufacture Microchannel plate (MCP) devices capable of high gain / low ion feedback operation, on...

  17. Speech enhancement algorithm for high noise environment%一种新的强噪声环境下的语音增强算法

    Institute of Scientific and Technical Information of China (English)

    蒋建中; 张东方; 张连海

    2013-01-01

    针对强噪声环境下语音增强中噪声估计和先验信噪比估计算法导致的语音失真和音乐噪声的问题,利用语音和噪声的统计模型的对称性得到一种噪声幅度的估计值为参考,提出了一种噪声估计算法,改进了先验信噪比估计算法,形成了一种新的增强算法,适用于强噪声环境下的语音增强。由仿真实验给出的客观评分看出,在0 dB乃至-5 dB条件下,给出信噪比估计算法能够有效减小信号失真,基本上没有残留音乐噪声。%The trade-off among amount of noise reduction, the level of musical residual noise and the speech distortion in high noise environment has to be solved. This study focuses on noise estimation to boost the performance of speech enhancement algorithms by combining statistical estimators of the spectral magnitude of the speech and noise. The noise spectral magnitude estimator is derived from the speech magnitude estimator, with which a modified a priori SNR estimation is given. The simulated experiments indicate that significant improvement could be achieved. For the speech enhancement, the algorithm obtains an ob-vious improvement in reducing speech distortion, with little musical noise retained.

  18. Impedance spectroscopy on ceramic materials at high temperatures, considering stray fields and electromagnetic noise

    Science.gov (United States)

    Müller, T. M.; Meinhardt, J.; Raether, F.

    2013-01-01

    Impedance spectroscopy of many ceramics is a challenge due to their high electrical resistance. Small disturbances can significantly alter the measuring results. In the present paper, it is shown how impedance measurements can be performed in an electromagnetically noisy ac furnace, using consequent Faraday shielding of the sample and the electrical connections. As example, the conductivity data of alumina was measured between room temperature and 1000 °C and compared to literature data. In addition, a correction method for the calculation of permittivity was developed to consider the stray fields in the sample-electrode setup. The distribution of the electrical field was simulated by finite element (FE) methods for different sample geometries and electrode arrangements. The deviations from the behavior of an ideal plate capacitor follow a linear trend and are in the order of 5% to 20% for an experimentally reasonable range of sample thicknesses. To check the theoretical results experimentally, alumina samples of varying thickness were measured. The customary calculation of permittivity leads to a clear trend with sample thickness, whereas the correction from the FE-simulation produces almost constant values of the relative permittivity.

  19. High-Frequency EMI Noise Suppression by Polymer-Based Composite Magnetic Materials

    Directory of Open Access Journals (Sweden)

    Rastislav Dosoudil

    2008-01-01

    Full Text Available The complex permeability and EM-wave absorption properties of hybrid polymer-based composite magneticmaterials (with MnZn and LiZn ferrite fillers and PVC matrix prepared with constant total filler content (65 vol% andparticle size (0-250 mm have been investigated in the 1-1000 MHz frequency range. Within this filler concentrationthe permeability of composites changed continuously with the change of ferrite filler content ratio between two types offerrite fillers. The observed relaxation type of permeability dispersion was due to the domain wall and natural ferromagneticresonance phenomena and was also attributed to the high damping of spin motion. Measured values of permeability wereused to determine the EM-wave absorption properties (return loss RL, matching frequency fm, matching thickness dm andbandwidth Df for RL £ -20 dB. The calculation of these properties was based on a model of single-layered absorber backedby a perfect conductor using transmission-line and EM-field theory. The composite with the volume fraction ratio of hybridMnZn:LiZn ferrite filler set to 0.5:0.5 has shown a return loss of -57 dB (> 99 % power absorption at fm = 714 MHz with the-20 dB bandwidth of Df = 232 MHz for an absorber thickness of 7.79 mm.

  20. Shot noise effect on noise source and noise parameter of 10-nm-scale quasi-ballistic n-/p-type MOS devices

    Science.gov (United States)

    Jeon, Jongwook; Kang, Myounggon

    2016-05-01

    In this work, we investigated the noise source and noise parameters of a quasi-ballistic MOSFET at the high-frequency regime. We presented the shot noise properties in the measured drain current noise and its impact on the induced gate noise and the noise parameters of 10-nm-scale n-/p-type MOS (N/PMOS) devices for the first time. The measured noise sources and noise parameters were carefully analyzed with the shot and thermal noise models in all operation regions. On the basis of the results, new noise parameter models are proposed and the noise performance improvement in the quasi-ballistic regime is shown.

  1. Phase Noise Enhancement of the GaAs High Electron Mobility Transistors Using Micromachined Cavity Resonators at Ka-band

    Science.gov (United States)

    Song, Insang; Kim, Chungwoo; Kwon, Youngwoo; Cheon, Changyul; Song, Cimoo

    1999-06-01

    We introduce a new structure of the micromachined cavity resonator coupled GaAs-based oscillator to enhance the phase noise and the frequency stability. The oscillator and the cavity are designed for Ka-band applications. Compared to the free running oscillator, the cavity resonator coupled oscillator showed the phase noise enhancement of about 20 dB. The phase noises of about -110 and -85 dBc/Hz are obtained at 1 MHz and 100 kHz offset frequency, respectively. The frequency pushing for the gate bias of the cavity coupled oscillator is about two order of magnitude less than that of the free running oscillator.

  2. Design Optimization and Fabrication of High-Sensitivity SOI Pressure Sensors with High Signal-to-Noise Ratios Based on Silicon Nanowire Piezoresistors

    Directory of Open Access Journals (Sweden)

    Jiahong Zhang

    2016-10-01

    Full Text Available In order to meet the requirement of high sensitivity and signal-to-noise ratios (SNR, this study develops and optimizes a piezoresistive pressure sensor by using double silicon nanowire (SiNW as the piezoresistive sensing element. First of all, ANSYS finite element method and voltage noise models are adopted to optimize the sensor size and the sensor output (such as sensitivity, voltage noise and SNR. As a result, the sensor of the released double SiNW has 1.2 times more sensitivity than that of single SiNW sensor, which is consistent with the experimental result. Our result also displays that both the sensitivity and SNR are closely related to the geometry parameters of SiNW and its doping concentration. To achieve high performance, a p-type implantation of 5 × 1018 cm−3 and geometry of 10 µm long SiNW piezoresistor of 1400 nm × 100 nm cross area and 6 µm thick diaphragm of 200 µm × 200 µm are required. Then, the proposed SiNW pressure sensor is fabricated by using the standard complementary metal-oxide-semiconductor (CMOS lithography process as well as wet-etch release process. This SiNW pressure sensor produces a change in the voltage output when the external pressure is applied. The involved experimental results show that the pressure sensor has a high sensitivity of 495 mV/V·MPa in the range of 0–100 kPa. Nevertheless, the performance of the pressure sensor is influenced by the temperature drift. Finally, for the sake of obtaining accurate and complete information over wide temperature and pressure ranges, the data fusion technique is proposed based on the back-propagation (BP neural network, which is improved by the particle swarm optimization (PSO algorithm. The particle swarm optimization–back-propagation (PSO–BP model is implemented in hardware using a 32-bit STMicroelectronics (STM32 microcontroller. The results of calibration and test experiments clearly prove that the PSO–BP neural network can be effectively applied

  3. Noise Pollution

    Science.gov (United States)

    ... Search Clean Air Act Overview Share Facebook Twitter Google+ Pinterest Contact Us Clean Air Act Title IV - ... noises in the community (from your neighbor, boom cars, lawn equipment, etc.) and from commercial businesses (factory, ...

  4. A novel match-line selective charging scheme for high-speed, low-power and noise-tolerant content-addressable memory

    KAUST Repository

    Hasan, Muhammad Mubashwar

    2010-06-01

    Content-addressable memory (CAM) is an essential component for high-speed lookup intensive applications. This paper presents a match-line selective charging technique to increase speed and reduce the energy per bit per search while increasing the noise-tolerance. Simulation in TSMC 0.18 μm technology with 64×72 Ternary CAM shows the match-line energy reduction of 45% compared to the conventional currentsaving scheme with the reduction of minimum cycle time by 68% and the improvement of noise-tolerance by 96%.

  5. AlGaN/GaN High Electron Mobility Transistors for High-Power and Low-Noise Applications

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaoguang; Dabiran Amir M; Hartmann Ralf; Chow Peter P

    2004-01-01

    The paper different aspects of MBE growth of nitride-based high electron mobility transistor (HEMT) and dilute-nitride, AlGaAsN-based, heterostructures were discussed. New growth and monitoring techniques developed at SVT were described and recent device results were presented.

  6. 箱式大功率电机的噪声控制%Noise Control of a High Power Electric Motor

    Institute of Scientific and Technical Information of China (English)

    彭若龙; 夏博雯; 杨涛

    2014-01-01

    针对国内某箱式大功率电机的噪声问题,开展了整体系统的噪声控制。通过噪声测试分析确定声源的性质和传递路径;在现有电机结构的基础上,研究设计了减振降噪方案和开发相应的声学材料,由此实施和评价噪声控制的方案。相比原有消声处理后的电机最终总体噪声从89 dB降低到81 dB,优于现有要求的85 dB的指标。%Noise control of a domestic typical high-power electric motor is studied. Based on the measurement and analysis of the noise of the motor, the contribution and transfer path of the noise sources are determined. The noise reduction scheme is designed and the corresponding acoustic material is developed and applied to the electric motor. The results show that in comparison with the original motor, the overall sound level of the noise can be decreased by 8 dB, which effectively improves the compatibility of this type of motors.

  7. Noise evaluation of silicon strip super-module with ABCN250 readout chips for the ATLAS detector upgrade at the High Luminosity LHC

    Energy Technology Data Exchange (ETDEWEB)

    Todome, K., E-mail: todome@hep.phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8551 (Japan); Solid State Div., Hamamatsu Photonics K.K., 1126-1, Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); Jinnouchi, O. [Department of Physics, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8551 (Japan); Solid State Div., Hamamatsu Photonics K.K., 1126-1, Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); Clark, A.; Barbier, G.; Cadoux, F.; Favre, Y.; Ferrere, D.; Gonzalez-Sevilla, S.; Iacobucci, G.; La Marra, D.; Perrin, E.; Weber, M. [DPNC, University of Geneva, CH-1211 Geneva 4 (Switzerland); Solid State Div., Hamamatsu Photonics K.K., 1126-1, Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); Ikegami, Y.; Nakamura, K.; Takubo, Y.; Unno, Y. [Institute of Particle and Nuclear Study, KEK, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Solid State Div., Hamamatsu Photonics K.K., 1126-1, Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); Takashima, R. [Department of Science Education, Kyoto University of Education, Kyoto 612-8522 (Japan); Solid State Div., Hamamatsu Photonics K.K., 1126-1, Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); Tojo, J. [Department of Physics, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Solid State Div., Hamamatsu Photonics K.K., 1126-1, Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); Kono, T. [Ochadai Academic Production, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo 112-8610 (Japan); Solid State Div., Hamamatsu Photonics K.K., 1126-1, Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); and others

    2016-09-21

    Toward High Luminosity LHC (HL-LHC), the whole ATLAS inner tracker will be replaced, including the semiconductor tracker (SCT) which is the silicon micro strip detector for tracking charged particles. In development of the SCT, integration of the detector is the important issue. One of the concepts of integration is the “super-module” in which individual modules are assembled to produce the SCT ladder. A super-module prototype has been developed to demonstrate its functionality. One of the concerns in integrating the super-modules is the electrical coupling between each module, because it may increase intrinsic noise of the system. To investigate the electrical performance of the prototype, the new Data Acquisition (DAQ) system has been developed by using SEABAS. The electric performance of the super-module prototype, especially the input noise and random noise hit rate, was investigated by using SEABAS system.

  8. Cross-spectrum Measurement of Thermal-noise Limited Oscillators

    CERN Document Server

    Hati, Archita; Howe, David A

    2015-01-01

    Cross-spectrum analysis is a commonly-used technique for the detection of phase and amplitude noise of a signal in the presence of interfering noise. It extracts the desired correlated noise from two time series in the presence of uncorrelated interfering noise. Recently, we demonstrated that the phase-inversion (anti-correlation) effect due to AM noise leakage can cause complete or partial collapse of the cross-spectral function. In this paper, we discuss the newly discovered effect of anti-correlated thermal noise that originates from the common-mode power divider (splitter), an essential component in a cross-spectrum noise measurement system. We studied this effect for different power splitters and discuss its influence on the measurement of thermal-noise limited oscillators. An oscillator whose thermal noise is primarily set by the 50 ohm source resistance is referred to as a thermally-limited oscillator. We provide theory, simulation and experimental results. In addition, we expand this study to reveal h...

  9. A low noise all-fiber interferometer for high resolution frequency modulated atomic force microscopy imaging in liquids.

    Science.gov (United States)

    Rasool, Haider I; Wilkinson, Paul R; Stieg, Adam Z; Gimzewski, James K

    2010-02-01

    We have developed a low noise all-fiber interferometer for use as the deflection sensor in liquid environment frequency modulated atomic force microscopy (FM-AFM). A detailed description and rationale for the choice of the critical components are provided along with the design of a simple alignment assembly. The optimization of the deflection sensor toward achieving the highest possible sensitivity and lowest deflection noise density is discussed in the context of an ideal interference cavity. Based on the provided analysis we have achieved deflection noise densities of 2 fm/square root(Hz) on commercially available cantilevers in both ambient and liquid environments. The low noise interferometer works without the need for differential detection, special focusing lenses, or polarization sensitive optics, dramatically simplifying measurements. True atomic resolution imaging of muscovite mica by FM-AFM in water is demonstrated using the developed deflection sensor.

  10. The sound of high winds : The effect of atmospheric stability on wind turbine sound and microphone noise

    NARCIS (Netherlands)

    van den Berg, G.P.

    2006-01-01

    This is the story of the discovery of a new phenomenon: why wind turbines sound different at night time. This discovery was related to a problem in society, namely that of perceived noise by residents living close to such turbines.

  11. Investigation into external noise of a high-speed train at different speeds%不同速度高速列车车外噪声的调查研究

    Institute of Scientific and Technical Information of China (English)

    Bin HE; Xin-biao XIAO; Qiang ZHOU; Zhi-hui LI; Xue-song JIN‡

    2014-01-01

    This paper presents a detailed discussion of the experimental analysis of the external noise produced by a Chinese high-speed train traveling at different speeds. Based on the delay and sum beam-forming method, a microphone array with 78 microphones was used to measure the external noise produced by the train moving at speeds of up to 390 km/h. The experiment and its analysis showed that the main noise produced by the train originates in three areas: the wheel/rail system (or bogies), the pantograph, and the inter-coach gaps of the train. The frequency characteristics and sound exposure level (SEL) of these main sources were analyzed for different speeds. In the range of 5000 Hz, the SELs of the three main noise sources are clearly identified. Along the vertical height of the train, as seen from the rail head, the maximum noise levels always occur in the wheel/rail area. At different measurement field points, the predominant noise components of the total noise have different frequencies that vary with the train speed. Furthermore, at the measurement points, the rolling noise has a greater contribution to the total noise than the aerodynamic noise. The experimental results and their corresponding analysis are very useful for the control and reduction of the external noise produced by high-speed trains.

  12. High-resolution terahertz spectroscopy with a noise radiation source based on high-T c superconductors

    Science.gov (United States)

    Sobakinskaya, E.; Vaks, V. L.; Kinev, N.; Ji, M.; Li, M. Y.; Wang, H. B.; Koshelets, V. P.

    2017-01-01

    Stochastic fields can play a ‘constructive’ role in their interaction with quantum systems. In this paper, we demonstrate that the phase-diffusion field (PDF) in the terahertz range (THz) induces macroscopic polarization in molecular gas. We explain the observed effect using a simple model in which the PDF is treated as a series of ultrashort pulses of a regular signal, resulting in transient absorption in molecular gas. The experimental investigation of this effect is carried out using ammonia, and the PDF is generated by an oscillator based on stacks of Bi2Sr2CaCu2O8 intrinsic Josephson junctions. These radiation sources do not require a phase-lock loop system to provide high resolution, which simplifies the spectrometer considerably. The PDF radiation sources open up new horizons for the development of compact high-resolution THz spectrometers and applications thereof.

  13. A High Signal-to-Noise UV Spectrum of NGC 7469 New Support for Reprocessing of Continuum Radiation

    CERN Document Server

    Kriss, G A; Crenshaw, D M; Zheng, W; Kriss, Gerard A.; Peterson, Bradley M.; Zheng, Wei

    2000-01-01

    From 1996 June 10 to 1996 July 29 the International AGN Watch monitored the Seyfert 1 galaxy NGC 7469 using IUE, RXTE, and a network of ground-based observatories. On 1996 June 18, in the midst of this intensive monitoring period, we obtained a high signal-to-noise snapshot of the UV spectrum from 1150-3300 A using the FOS on HST. This spectrum allows us to disentangle the UV continuum more accurately from the broad wings of the emission lines, to identify clean continuum windows free of contaminating emission and absorption, and to deblend line complexes such as Lya+NV, CIV+HeII+OIII], SiIII]+CIII], and MgII+FeII. Using the FOS spectrum as a template, we have fit and extracted line and continuum fluxes from the IUE monitoring data. The cleaner continuum extractions confirm the discovery of time delays between the different UV continuum bands by Wanders et al. Our new measurements show delays increasing with wavelength for continuum bands centered at 1485 A, 1740 A and 1825 A relative to 1315 A with delays of...

  14. The Ultraviolet Emission Properties of Five Low-Redshift Active Galactic Nuclei at High Signal to Noise and Spectral Resolution

    CERN Document Server

    Laor, A; Jannuzi, B T; Schneider, D P; Green, R F; Hartig, G F; Laor, Ari; Bahcall, John N.; Jannuzi, Buell T.; Schneider, Donald P.; Green, IAS; Richard F.; Hartig, NOAO; George F.; ScI, ST

    1994-01-01

    We analyze the ultraviolet (UV) emission line and continuum properties of five low-redshift active galactic nuclei (four luminous quasars: PKS~0405$-$123, H1821+643, PG~0953+414, and 3C273, and one bright Seyfert 1 galaxy: Mrk~205). The HST spectra have higher signal-to-noise ratios (typically $\\sim 60$ per resolution element) and spectral resolution ($R = 1300$) than all previously- published UV spectra used to study the emission characteristics of active galactic nuclei. We include in the analysis ground-based optical spectra covering \\hb\\ and the narrow [O~III]~$\\lambda\\lambda$4959,5007 doublet. The following new results are obtained: \\lyb/\\lya=0.03$-$0.12 for the four quasars, which is the first accurate measurement of the long-predicted \\lyb\\ intensity in QSOs. The cores of \\lya\\ and C~IV are symmetric to an accuracy of better than 2.5\\% within about 2000~km~s$^{-1}$ of the line peak. This high degree of symmetry of \\lya\\ argues against models in which the broad line cloud velocity field has a significan...

  15. Nano-domains of high viscosity and stiffness mapped in the cell membrane by thermal noise imaging

    Science.gov (United States)

    Hsu, Yunhsiang; Pralle, Arnd

    2012-02-01

    The cell membrane is thought to contain spatial domains, created by cholesterol-lipid clusters and by interactions with the membrane cytoskeleton. The influence of these domains on membrane protein mobility and cell signaling has clearly been demonstrate. Yet, due to their small size and transient nature, the cholesterol stabilized domains cannot be visualized directly. We show here that thermal noise imaging (TNI) which tracks the diffusion of a colloid labeled membrane protein with microsecond and nanometer precision, can visualize cholesterol stabilized domains, also know as lipid raft, in intact cells. Using TNI to confine a single membrane protein to diffuse for seconds in an area of 300nm x 300nm provides sufficient data for high resolutions maps of the local diffusion, local attraction potentials and membrane stiffness. Using a GPI-anchored GFP molecule to probe the membrane of PtK2 cells we detect domains of increased membrane stiffness, which also show increase viscosity and are the preferred location for the GPI-anchored protein. These domains are further stabilized by addition of ganglioside cross linking toxins and disappear after removal of the cholesterol.

  16. Unified aeroacoustics analysis for high speed turboprop aerodynamics and noise. Volume 4: Computer user's manual for UAAP turboprop aeroacoustic code

    Science.gov (United States)

    Menthe, R. W.; Mccolgan, C. J.; Ladden, R. M.

    1991-01-01

    The Unified AeroAcoustic Program (UAAP) code calculates the airloads on a single rotation prop-fan, or propeller, and couples these airloads with an acoustic radiation theory, to provide estimates of near-field or far-field noise levels. The steady airloads can also be used to calculate the nonuniform velocity components in the propeller wake. The airloads are calculated using a three dimensional compressible panel method which considers the effects of thin, cambered, multiple blades which may be highly swept. These airloads may be either steady or unsteady. The acoustic model uses the blade thickness distribution and the steady or unsteady aerodynamic loads to calculate the acoustic radiation. The users manual for the UAAP code is divided into five sections: general code description; input description; output description; system description; and error codes. The user must have access to IMSL10 libraries (MATH and SFUN) for numerous calls made for Bessel functions and matrix inversion. For plotted output users must modify the dummy calls to plotting routines included in the code to system-specific calls appropriate to the user's installation.

  17. Optimization of Fixed Microphone Array in High Speed Train Noises Identification Based on Far-Field Acoustic Holography

    Directory of Open Access Journals (Sweden)

    Rujia Wang

    2017-01-01

    Full Text Available Acoustical holography has been widely applied for noise sources location and sound field measurement. Performance of the microphones array directly determines the sound source recognition method. Therefore, research is very important to the performance of the microphone array, its array of applications, selection, and how to design instructive. In this paper, based on acoustic holography moving sound source identification theory, the optimization method is applied in design of the microphone array, we select the main side lobe ratio and the main lobe area as the optimization objective function and then put the optimization method use in the sound source identification based on holography, and finally we designed this paper to optimize microphone array and compare the original array of equally spaced array with optimization results; by analyzing the optimization results and objectives, we get that the array can be achieved which is optimized not only to reduce the microphone but also to change objective function results, while improving the far-field acoustic holography resolving effect. Validation experiments have showed that the optimization method is suitable for high speed trains sound source identification microphone array optimization.

  18. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    Energy Technology Data Exchange (ETDEWEB)

    François, B. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France); INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Calosso, C. E.; Micalizio, S. [INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Abdel Hafiz, M.; Boudot, R. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France)

    2015-09-15

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  19. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks.

    Science.gov (United States)

    François, B; Calosso, C E; Abdel Hafiz, M; Micalizio, S; Boudot, R

    2015-09-01

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad(2)/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad(2)/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10(-14) for the Cs cell clock and 2 × 10(-14) for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10(-15) level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  20. Combining Simulated and Experimental Data to Simulate Ultrasonic Array Data From Defects in Materials With High Structural Noise.

    Science.gov (United States)

    Bloxham, Harry A; Velichko, Alexander; Wilcox, Paul David

    2016-12-01

    Ultrasonic nondestructive testing inspections using phased arrays are performed on a wide range of components and materials. All real inspections suffer, to varying extents, from coherent noise, including image artifacts and speckle caused by complex geometries and grain scatter, respectively. By its nature, this noise is not reduced by averaging; however, it degrades the signal-to-noise ratio of defects and ultimately limits their detectability. When evaluating the effectiveness of an inspection, a large pool of data from samples containing a range of different defects are important to estimate the probability of detection of defects and to help characterize them. For a given inspection, coherent noise is easy to measure experimentally but hard to model realistically. Conversely, the ultrasonic response of defects can be simulated relatively easily. This paper proposes a novel method of simulating realistic array data by combining noise-free simulations of defect responses with coherent noise taken from experimental data. This removes the need for costly physical samples with known defects to be made and allows for large data sets to be created easily.

  1. Model of flicker noise effects on phase noise in oscillators

    Science.gov (United States)

    Centurelli, Francesco; Ercolani, Alessandro; Tommasino, Pasquale; Trifiletti, Alessandro

    2003-05-01

    Phase noise models that describe the near-carrier spectrum in an accurate but insightful way are needed, to better optimize the oscillator design. In this paper we present a model to describe the effect of flicker noise sources on the phase noise of an oscillator, that can be applied both to linear oscillators and to nonlinear structures like relaxation and ring oscillators, so extending previous works that considered only the effect of the flicker noise superimposed to the control voltage of a VCO. In the phase noise of an oscillator we can separate the effect of high frequency noise sources, that can be described by a short-time-constant system, and the effect of low frequency noises (mostly flicker sources), described by a system with time constants much slower than the oscillation period. Flicker noise has been considered to cause a change in the circuit bias point; this bias point change can be mapped in a shift of the oscillation frequency by exploiting Barkhausen conditions (for linear oscillators) or obtaining this link by simulations. The power spectral density of the oscillator can then be obtained as the probability distribution of the oscillation frequency, starting from the flicker noise probability distribution. If the effect of high frequency noise sources is also taken into account, the overall oscillator spectrum can be obtained as a convolution of the spectrum due to flicker sources with the Lorentzian-shaped spectrum due to white noise sources, in analogy with the description of inhomogeneous broadening of laser linewidth.

  2. A Low-Noise CMOS THz Imager Based on Source Modulation and an In-Pixel High-Q Passive Switched-Capacitor N-Path Filter

    Directory of Open Access Journals (Sweden)

    Assim Boukhayma

    2016-03-01

    Full Text Available This paper presents the first low noise complementary metal oxide semiconductor (CMOS terahertz (THz imager based on source modulation and in-pixel high-Q filtering. The 31 × 31 focal plane array has been fully integrated in a 0 . 13 μ m standard CMOS process. The sensitivity has been improved significantly by modulating the active THz source that lights the scene and performing on-chip high-Q filtering. Each pixel encompass a broadband bow tie antenna coupled to an N-type metal-oxide-semiconductor (NMOS detector that shifts the THz radiation, a low noise adjustable gain amplifier and a high-Q filter centered at the modulation frequency. The filter is based on a passive switched-capacitor (SC N-path filter combined with a continuous-time broad-band Gm-C filter. A simplified analysis that helps in designing and tuning the passive SC N-path filter is provided. The characterization of the readout chain shows that a Q factor of 100 has been achieved for the filter with a good matching between the analytical calculation and the measurement results. An input-referred noise of 0 . 2 μ V RMS has been measured. Characterization of the chip with different THz wavelengths confirms the broadband feature of the antenna and shows that this THz imager reaches a total noise equivalent power of 0 . 6 nW at 270 GHz and 0 . 8 nW at 600 GHz.

  3. A Low-Noise CMOS THz Imager Based on Source Modulation and an In-Pixel High-Q Passive Switched-Capacitor N-Path Filter.

    Science.gov (United States)

    Boukhayma, Assim; Dupret, Antoine; Rostaing, Jean-Pierre; Enz, Christian

    2016-03-03

    This paper presents the first low noise complementary metal oxide semiconductor (CMOS) deletedCMOS terahertz (THz) imager based on source modulation and in-pixel high-Q filtering. The 31 × 31 focal plane array has been fully integrated in a 0 . 13 μ m standard CMOS process. The sensitivity has been improved significantly by modulating the active THz source that lights the scene and performing on-chip high-Q filtering. Each pixel encompass a broadband bow tie antenna coupled to an N-type metal-oxide-semiconductor (NMOS) detector that shifts the THz radiation, a low noise adjustable gain amplifier and a high-Q filter centered at the modulation frequency. The filter is based on a passive switched-capacitor (SC) N-path filter combined with a continuous-time broad-band Gm-C filter. A simplified analysis that helps in designing and tuning the passive SC N-path filter is provided. The characterization of the readout chain shows that a Q factor of 100 has been achieved for the filter with a good matching between the analytical calculation and the measurement results. An input-referred noise of 0 . 2 μ V RMS has been measured. Characterization of the chip with different THz wavelengths confirms the broadband feature of the antenna and shows that this THz imager reaches a total noise equivalent power of 0 . 6 nW at 270 GHz and 0 . 8 nW at 600 GHz.

  4. Estudo do espectro sonoro nos limiares de altas frequências em trabalhadores expostos ao ruído Study of the noise spectrum on high frequency thresholds in workers exposed to noise

    Directory of Open Access Journals (Sweden)

    Aurea Oliveira Canha Ottoni

    2012-08-01

    between the various industries, with a greater prevalence of the metallurgical. CONCLUSION: The use of noise pressure measuring device, coupled to a frequency analyzer and high frequency audiometric assessment yielded an early detection of hearing damage, helping better organize preventive measures.

  5. FET noise studies

    Science.gov (United States)

    Pucel, R. A.

    1981-03-01

    The GaAs FET oscillator is an alternative device for voltage-controlled oscillator (VCO) applications because of its inherent wide-band electronic tunability, the variety of operating modes possible such as common source, common gate, etc., and the ease of circuit design. However, it has one major drawback, namely, its high near-carrier 1/f noise which makes it unsuitable for many applications, such as radar systems. This report describes the progress made during the report period in understanding the physical mechanisms responsible for this noise. During this period, an extensive experimental study was made of the 1/f noise properties of a variety of oscillators constructed of FET chips fabricated under controlled conditions. Using in-house grown epitaxial wafers, FET's were fabricated from both buffered and unbuffered active layers, with and without epitaxially grown contact layers, and with and without surface passivation. The experimental results show a good correlation between the trap-generated 1/f baseband noise and the near-carrier 1/f FM noise. The primary sources of the noise are presumed to be either deep traps within the depletion layer under the gate or surface states at the gate-semiconductor interface, probably the latter. An improvement of the order of 10 dB in the near carrier FM noise level is obtained when a buffer layer separates the active layer from the substrate. Optical experiments indicated an electron trap level approximately 0.41 eV below the conduction band. A noise model was devised to explain the modulation process for upconverting baseband 1/f noise to the carrier band by depletion layer modulation.

  6. Ambiguity functions and noise floor suppression in random noise radar

    Science.gov (United States)

    Axelsson, Sune R. J.

    2006-09-01

    Noise radar can be used in a great number of applications including SAR. The non-periodic waveform suppresses the range ambiguity and reduces the probability of intercept and interference. Due to the randomness of the waveform, a noise floor limiting the possible side lobe suppression accompanies the correlation integral involved. In strong clutter scenes with dominant reflectors, the induced noise floor can be too high and further suppression is needed. In this paper, the ambiguity function of random noise waveforms is first analyzed, and an improved formulation is introduced to include the noise floor effect. The use of mismatched filtering for improved sidelobe suppression is then discussed. Finally, an iterative subtraction algorithm is analyzed for noise floor cancellation in the presence of dominating reflectors. This method is successfully tested on random step frequency radar data and noise sodar data.

  7. Intensity noise reduction of a high-power nonlinear femtosecond fiber amplifier based on spectral-breathing self-similar parabolic pulse evolution

    Science.gov (United States)

    Wang, Sijia; Liu, Bowen; Song, Youjian; Hu, Minglie

    2016-04-01

    We report on a simple passive scheme to reduce the intensity noise of high-power nonlinear fiber amplifiers by use of the spectral-breathing parabolic evolution of the pulse amplification with an optimized negative initial chirp. In this way, the influences of amplified spontaneous emission (ASE) on the amplifier intensity noise can be efficiently suppressed, owing to the lower overall pulse chirp, shorter spectral broadening distance, as well as the asymptotic attractive nature of self-similar pulse amplification. Systematic characterizations of the relative intensity noise (RIN) of a free-running nonlinear Yb-doped fiber amplifier are performed over a series of initial pulse parameters. Experiments show that the measured amplifier RIN increases respect to the decreased input pulse energy, due to the increased amount of ASE noise. For pulse amplification with a proper negative initial chirp, the increase of RIN is found to be smaller than with a positive initial chirp, confirming the ASE noise tolerance of the proposed spectral-breathing parabolic amplification scheme. At the maximum output average power of 27W (25-dB amplification gain), the incorporation of an optimum negative initial chirp (-0.84 chirp parameter) leads to a considerable amplifier root-mean-square (rms) RIN reduction of ~20.5% (integrated from 10 Hz to 10 MHz Fourier frequency). The minimum amplifier rms RIN of 0.025% (integrated from 1 kHz to 5 MHz Fourier frequency) is obtained along with the transform-limited compressed pulse duration of 55fs. To our knowledge, the demonstrated intensity noise performance is the lowest RIN level measured from highpower free-running femtosecond fiber amplifiers.

  8. Aerodynamic noise numerical simulation and noise reduction of high-speed train bogie section%高速列车转向架部位气动噪声数值模拟及降噪研究

    Institute of Scientific and Technical Information of China (English)

    黄莎; 杨明智; 李志伟; 徐刚

    2011-01-01

    In order to decrease the aerodynamic noise of train bogie section, three-dimensional, large eddy simulation and FW-H acoustic model were adopted to simulate the aerodynamic noise outside high-speed train bogie section based on Lighthill acoustic theory, and noise reduction advice was proposed. The results show that the aerodynamic noise is a kind of wide frequency noise which exits in wide frequency band without obvious main frequency. The acoustic pressure amplitude of every test point is great at low frequency, decreasing with the increase of frequency, and the acoustic pressure level within 1/3 octave band frequency ranges from 315 Hz to 1 250 Hz. Given a certain incoming wind speed, the total acoustic pressure level is lower when the test point is farther from the noise source. Once aprons are set in bogie sections, acoustic pressure amplitude and total acoustic pressure level of each point reduce compared with that without apron, respectively with an average reduction of about 8% and 1.3 dBA at the speed of 300 km/h. Besides, the average reduction will come to 12% and 2.08 dBA when the apron area increases properly, making noise reduction more effective apparently.%基于Lighthill声学理论,采用三维、LES大涡模拟和FW-H声学模型对高速列车转向架部位气动噪声进行数值模拟,并提出降噪改进意见.研究结果表明:转向架部位气动噪声在很宽的频带内存在,无明显的主频率,是一种宽频噪声;各监测点气动噪声频谱在低频时幅值较大,随着频率的升高,幅值下降,1/3倍频程A声压级主要集中在315~1 250 Hz频率范围内;当来流速度一定时,距离气动噪声源越远,声压级幅值和总声压级越小;在列车转向架部位设置裙板后,运行速度为300 km/h时,车外声压级幅值较无裙板时有所减小,平均降幅约为8%,总声压级平均降幅1.3 dBA;适当增加裙板面积后,声压级幅值平均降幅达到12%,总声压级平均降幅2.08dBA,降噪效果较明显.

  9. Versatile quantitative phase imaging system applied to high-speed, low noise and multimodal imaging (Conference Presentation)

    Science.gov (United States)

    Federici, Antoine; Aknoun, Sherazade; Savatier, Julien; Wattellier, Benoit F.

    2017-02-01

    Quadriwave lateral shearing interferometry (QWLSI) is a well-established quantitative phase imaging (QPI) technique based on the analysis of interference patterns of four diffraction orders by an optical grating set in front of an array detector [1]. As a QPI modality, this is a non-invasive imaging technique which allow to measure the optical path difference (OPD) of semi-transparent samples. We present a system enabling QWLSI with high-performance sCMOS cameras [2] and apply it to perform high-speed imaging, low noise as well as multimodal imaging. This modified QWLSI system contains a versatile optomechanical device which images the optical grating near the detector plane. Such a device is coupled with any kind of camera by varying its magnification. In this paper, we study the use of a sCMOS Zyla5.5 camera from Andor along with our modified QWLSI system. We will present high-speed live cell imaging, up to 200Hz frame rate, in order to follow intracellular fast motions while measuring the quantitative phase information. The structural and density information extracted from the OPD signal is complementary to the specific and localized fluorescence signal [2]. In addition, QPI detects cells even when the fluorophore is not expressed. This is very useful to follow a protein expression with time. The 10 µm spatial pixel resolution of our modified QWLSI associated to the high sensitivity of the Zyla5.5 enabling to perform high quality fluorescence imaging, we have carried out multimodal imaging revealing fine structures cells, like actin filaments, merged with the morphological information of the phase. References [1]. P. Bon, G. Maucort, B. Wattellier, and S. Monneret, "Quadriwave lateral shearing interferometry for quantitative phase microscopy of living cells," Opt. Express, vol. 17, pp. 13080-13094, 2009. [2] P. Bon, S. Lécart, E. Fort and S. Lévêque-Fort, "Fast label-free cytoskeletal network imaging in living mammalian cells," Biophysical journal, 106

  10. Development of a portable low-cost and low-noise DC/DC high voltage switching power supply for optics application

    Energy Technology Data Exchange (ETDEWEB)

    Hung, K.-Y.; Chen, Y.-C. [Mingchi Univ. of Technology, Taishan, Taipei, Taiwan (China). Inst. of Mechanical and Electrical Engineering, Dept. of Mechanical Engineering

    2007-07-01

    A commercial power supply is bulky in size, very expensive and produces extremely noisy voltage, carrying approximately 45 mV of surge at the maximum. An avalanche photo diode (APD) is used to detect weak fluorescent signals, making it easy to generate extremely intensified noise, and degrading the S/N ratio. In order to resolve this problem, this paper discussed the development of a portable high voltage transformer-free direct current (DC) drive circuit module with low cost, noise, and power for photoelectric components. The module can be used on photoelectric components requiring high reverse voltage, such as APDs, piezo transformers, vacuum florescent displays, and micro electric machines. The low-noise module effectively reduced the thermal noise of photodiodes, leading to an improvement in the S/N ratio of photoelectric components by approximately 37 per cent. The module was described in detail. Several graphs and tables were presented, including a comparison between various types of converters; the design structure of the control unit circuit; and diagram of converted circuit diagram. It was concluded that the module was efficient, compact, and portable and designed with a transformer-free circuitry. In addition, the power supply module was successfully developed and would be much more feasible to use in developing portable products, such as digital cameras, and other advanced products. 1 tab., 4 figs.

  11. Computational and Experimental Fluid-Structure Interaction Analysis of a High-Lift Wing with a Slat-Cove Filler for Noise Reduction

    Science.gov (United States)

    Scholten, William D.; Patterson, Ryan D.; Hartl, Darren J.; Strganac, Thomas W.; Chapelon, Quentin H. C.; Turner, Travis

    2017-01-01

    Airframe noise is a significant component of overall noise produced by transport aircraft during landing and approach (low speed maneuvers). A significant source for this noise is the cove of the leading-edge slat. The slat-cove filler (SCF) has been shown to be effective at mitigating slat noise. The objective of this work is to understand the fluid-structure interaction (FSI) behavior of a superelastic shape memory alloy (SMA) SCF in flow using both computational and physical models of a high-lift wing. Initial understanding of flow around the SCF and wing is obtained using computational fluid dynamics (CFD) analysis at various angles of attack. A framework compatible with an SMA constitutive model (implemented as a user material subroutine) is used to perform FSI analysis for multiple flow and configuration cases. A scaled physical model of the high-lift wing is constructed and tested in the Texas A&M 3 ft-by-4-foot wind tunnel. Initial validation of both CFD and FSI analysis is conducted by comparing lift, drag and pressure distributions with experimental results.

  12. 高速列车车辆连接部位气动噪声数值模拟及降噪研究%Numerical simulation of aerodynamic noise and noise reduction of high-speed train connection section

    Institute of Scientific and Technical Information of China (English)

    黄莎; 梁习锋; 杨明智

    2012-01-01

    采用大涡模拟与声类比相结合的方法,对高速列车车辆连接部位不同尺寸参数时的气动噪声进行了数值模拟,并提出降噪改进方案.研究得到了高速列车以300km/h速度运行时车辆连接部位的气动噪声分布,结果表明:车辆连接部位气动噪声在很宽的频带内存在,是宽频噪声;各监测点气动噪声频谱在低频时幅值较大,随着频率的增大先增大后减小,1/3倍频程A声压级主要集中在315~1000Hz频率范围内;车辆连接部位不同尺寸参数中,气动噪声声压级幅值随着凹槽长度L和高度H的增大而有所增加;采用全风挡方案较无风挡时,有效避免气流在凹槽内剧烈扰动,气动噪声显著改善,声压级平均降幅约为9.4%,总声压级平均降幅4.27dBA;研究结果为低噪高速列车的初期研制设计提供科学依据.%Aerodynamic noise of high-speed train connection section with different parameters were simulated numerically adopting LES model companied with acoustic analogy and reducion improvement project was proposed. The aerodynamic noise distribution of high-speed train connection section at speed of 300km/h was obtained from the research, the results show that aerodynamic noise is a kind of wide frequency noise which exits in wide frequency band. The acoustic pressure amplitude of every test point is bigger at low frequency, increasing firstly then decreasing with the increase of frequency, and acoustic pressure level within 1/3 octave band frequency concentrates in the rage of 315~1000Hz; Among different parameters of train connection section, the acoustic pressure level amplitude increases with the increase of groove length and height; Compared with the project without windshield, the noise reduction effect of full windshield project is apparent, avoiding severe disturbance flow effectively, the average acoustic pressure level reductive amplitude is 9. 4% and the average total acoustic pressure level

  13. An adaptive algorithm for noise rejection.

    Science.gov (United States)

    Lovelace, D E; Knoebel, S B

    1978-01-01

    An adaptive algorithm for the rejection of noise artifact in 24-hour ambulatory electrocardiographic recordings is described. The algorithm is based on increased amplitude distortion or increased frequency of fluctuations associated with an episode of noise artifact. The results of application of the noise rejection algorithm on a high noise population of test tapes are discussed.

  14. A New Method for Estimating the Number of Harmonic Components in Noise with Application in High Resolution Radar

    Directory of Open Access Journals (Sweden)

    Radoi Emanuel

    2004-01-01

    Full Text Available In order to operate properly, the superresolution methods based on orthogonal subspace decomposition, such as multiple signal classification (MUSIC or estimation of signal parameters by rotational invariance techniques (ESPRIT, need accurate estimation of the signal subspace dimension, that is, of the number of harmonic components that are superimposed and corrupted by noise. This estimation is particularly difficult when the S/N ratio is low and the statistical properties of the noise are unknown. Moreover, in some applications such as radar imagery, it is very important to avoid underestimation of the number of harmonic components which are associated to the target scattering centers. In this paper, we propose an effective method for the estimation of the signal subspace dimension which is able to operate against colored noise with performances superior to those exhibited by the classical information theoretic criteria of Akaike and Rissanen. The capabilities of the new method are demonstrated through computer simulations and it is proved that compared to three other methods it carries out the best trade-off from four points of view, S/N ratio in white noise, frequency band of colored noise, dynamic range of the harmonic component amplitudes, and computing time.

  15. Extremely Metal-Poor Stars. VIII. High-Resolution, High-Signal-To-Noise Analysis of Five Stars with [Fe/H] < -3.5

    CERN Document Server

    Norris, J E; Beers, T C; Norris, John E.; Ryan, Sean G.; Beers, Timothy C.

    2001-01-01

    High-resolution, high-signal-to-noise ( = 85) spectra have been obtained for five stars -- CD-24:17504, CD-38:245, CS 22172-002, CS 22885-096, and CS 22949-037 -- having [Fe/H] < -3.5 according to previous lower S/N material. LTE model-atmosphere techniques are used to determine [Fe/H] and relative abundances, or their limits, for some 18 elements, and to constrain more tightly the early enrichment history of the Galaxy than is possible based on previous analyses. We compare our results with high-quality higher-abundance literature data for other metal-poor stars and with the canonical Galactic chemical enrichment results of Timmes et al. (1995) and obtain the following basic results: (1) Large supersolar values of [C/Fe] and [N/Fe], not predicted by the canonical models, exist at lowest abundance. For C at least, the result is difficult to attribute to internal mixing effects; (2) We confirm that there is {\\it no upward trend} in [$\\alpha$/Fe] as a function of [Fe/H], in contradistinction to some reports ...

  16. Theory of thermal phase noise in Michelson and Sagnac fiber interferometers

    Science.gov (United States)

    Wanser, Keith H.

    1994-09-01

    The intrinsic thermal phase noise spectra of the Michelson, Michelson with phase conjugate mirrors, and Sagnac fiber optic interferometers are presented. The thermal phase noise is maximum at dc and zero at the loop frequency for the Michelson with ordinary mirrors. Thermal phase noise eliminates the factor of two transducer phase sensitivity advantage of the Michelson over a comparable length Mach Zehnder. The Michelson with two phase conjugate mirrors exhibits identical noise to a Sagnac interferometer with the same total fiber length. The Sagnac exhibits common mode phase noise rejection at low frequencies and a broad maximum in the phase noise at the loop frequency of approximately 1 (mu) rad rms/(root)Hz for a 1 km fiber loop at 1319 nm.

  17. Low-noise low-power design for phase-locked loops multi-phase high-performance oscillators

    CERN Document Server

    Zhao, Feng

    2015-01-01

    This book introduces low-noise and low-power design techniques for phase-locked loops and their building blocks. It summarizes the noise reduction techniques for fractional-N PLL design and introduces a novel capacitive-quadrature coupling technique for multi-phase signal generation.  The capacitive-coupling technique has been validated through silicon implementation and can provide low phase-noise and accurate I-Q phase matching, with low power consumption from a super low supply voltage.  Readers will be enabled to pick one of the most suitable QVCO circuit structures for their own designs, without additional effort to look for the optimal circuit structure and device parameters. 

  18. Development of high-performance and low-noise axial-flow fan units in their local operating region

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Seung; Ha, Min Ho; Cheong, Cheol Ung [Pusan National University, Busan (Korea, Republic of); Kim, Tae Hoon [LG Electronics Inc., Changwon (Korea, Republic of)

    2015-09-15

    Aerodynamic and aeroacoustic performances of an axial-flow fan unit are improved by modifying its housing structure without changing the fan blade. The target axial-flow fan system is used to lower temperature of a compressor and a condenser in the machine room of a household refrigerator which has relatively high system resistance due to complex layout of structures inside it. First, the performance of the fan system is experimentally characterized by measuring its volume flow rate versus static pressure using a fan performance tester satisfying the AMCA (Air Movement and Control Association) regulation, AMCA 210-07. The detailed structure of flow driven by the fan is numerically investigated using a virtual fan performance tester based on computational fluid dynamics techniques. The prediction result reveals possible loss due to radial and tangential velocity components in the wake flow downstream of the fan. The length of the fan housing is chosen as a design parameter for improving the aerodynamic and aeroacoustic performances of the fan unit by reducing the identified radial and tangential velocity components. Three fan units with different housing lengths longer than the original are analyzed using the virtual fan performance tester. The results confirm the improved aerodynamic performance of the proposed three designs. The flow field driven by the proposed fan unit is closely examined to find the causes for the observed performance improvements, which ensures that the radial and tangential velocity components in the wake flow are reduced. Finally, the improved performance of the proposed fan systems is validated by comparing the P-Q and efficiency curves measured using the fan performance tester. The noise emission from the household refrigerator is also found to be lessened when the new fan units are installed.

  19. Airport noise and teratogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Edmonds, L.D.; Layde, P.M.; Erickson, J.D.

    1979-07-01

    It has been suggested that exposure to high-noise levels near major airports may cause increased incidence of birth defects in the offspring of parents residing near these airports. Using data gathered in Metropolitan Atlanta during 1970 to 1972, we compared the rates of seventeen categories of defects in high- and low-noise census tracts. No significant differences were observed. However, when we subdivided the category of central nervous system defects into several subcategories of specific defects, we noted a significantly increased incidence of spina bifida without hydrocephalus in the high-noise areas. Because of the small number of cases associated with this finding we did a matched case-control study using all cases of central nervous system defects born during the years 1968 to 1976. No significantly increased risk for residents in the high-noise areas was noted in this study. It is our opinion that noise or other factors associated with residence near airports are unlikely to be important environmental teratogens.

  20. Design of Low-Noise Output Amplifiers for P-channel Charge-Coupled Devices Fabricated on High-Resistivity Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Haque, S; Frost, F Dion R.; Groulx, R; Holland, S E; Karcher, A; Kolbe, W F; Roe, N A; Wang, G; Yu, Y

    2011-12-22

    We describe the design and optimization of low-noise, single-stage output amplifiers for p-channel charge-coupled devices (CCDs) used for scientific applications in astronomy and other fields. The CCDs are fabricated on high-resistivity, 4000–5000 -cm, n-type silicon substrates. Single-stage amplifiers with different output structure designs and technologies have been characterized. The standard output amplifier is designed with an n{sup +} polysilicon gate that has a metal connection to the sense node. In an effort to lower the output amplifier readout noise by minimizing the capacitance seen at the sense node, buried-contact technology has been investigated. In this case, the output transistor has a p{sup +} polysilicon gate that connects directly to the p{sup +} sense node. Output structures with buried-contact areas as small as 2 μm × 2 μm are characterized. In addition, the geometry of the source-follower transistor was varied, and we report test results on the conversion gain and noise of the various amplifier structures. By use of buried-contact technology, better amplifier geometry, optimization of the amplifier biases and improvements in the test electronics design, we obtain a 45% reduction in noise, corresponding to 1.7 e{sup -} rms at 70 kpixels/sec.

  1. Identification and Removal of High Frequency Temporal Noise in a Nd:YAG Macro-Pulse Laser Assisted with a Diagnostic Streak Camera

    Energy Technology Data Exchange (ETDEWEB)

    Kent Marlett, Bechtel Nevada; Ke-Xun Sun Bechtel Nevada

    2004-09-23

    This paper discusses the use of a reference streak camera (SC) to diagnose laser performance and guide modifications to remove high frequency noise from Bechtel Nevada's long-pulse laser. The upgraded laser exhibits less than 0.1% high frequency noise in cumulative spectra, exceeding National Ignition Facility (NIF) calibration specifications. Inertial Confinement Fusion (ICF) experiments require full characterization of streak cameras over a wide range of sweep speeds (10 ns to 480 ns). This paradigm of metrology poses stringent spectral requirements on the laser source for streak camera calibration. Recently, Bechtel Nevada worked with a laser vendor to develop a high performance, multi-wavelength Nd:YAG laser to meet NIF calibration requirements. For a typical NIF streak camera with a 4096 x 4096 pixel CCD, the flat field calibration at 30 ns requires a smooth laser spectrum over 33 MHz to 68 GHz. Streak cameras are the appropriate instrumentation for measuring laser amplitude noise at these very high frequencies since the upper end spectral content is beyond the frequency response of typical optoelectronic detectors for a single shot pulse. The SC was used to measure a similar laser at its second harmonic wavelength (532 nm), to establish baseline spectra for testing signal analysis algorithms. The SC was then used to measure the new custom calibration laser. In both spatial-temporal measurements and cumulative spectra, 6-8 GHz oscillations were identified. The oscillations were found to be caused by inter-surface reflections between amplifiers. Additional variations in the SC spectral data were found to result from temperature instabilities in the seeding laser. Based on these findings, laser upgrades were made to remove the high frequency noise from the laser output.

  2. Schottky diode characteristics and 1/f noise of high sensitivity reduced graphene oxide/Si heterojunction photodetector

    Science.gov (United States)

    Zhu, Miao; Li, Xinming; Li, Xiao; Zang, Xiaobei; Zhen, Zhen; Xie, Dan; Fang, Ying; Zhu, Hongwei

    2016-03-01

    Reduced graphene oxide (RGO)/Si Schottky diode has been reported nowadays to show excellent performances in photodetection and other photoelectrical devices. Different from pure graphene, there are large amounts of function groups and structural defects left on the base plane of RGO, which may influence the interfacial properties of RGO/Si Schottky diode. Herein, the barrier inhomogeneity and junction characteristics were systematically investigated to help to describe the interface of RGO/Si diode. From the perspective of its applications, the influences of gas molecule and noise properties are considered to be important. Thus, the photovoltaic performance of RGO/Si devices in air and vacuum is investigated to analyze their effects. Meanwhile, 1/f noise of RGO/Si diodes is investigated under air/vacuum conditions and varied temperatures. It is found that the devices in vacuum and under higher power incident light show much lower 1/f noise. These results are meaningful to the noise control and performance improvement in the development of Schottky diode based devices.

  3. High-resolution lithospheric structure beneath Mainland China from ambient noise and earthquake surface-wave tomography

    Science.gov (United States)

    Bao, X.; Song, X.; Li, J.

    2016-12-01

    We present a new high-resolution shear-velocity model of the lithosphere (down to about 160 km) beneath China using Rayleigh-wave tomography. We combined ambient noise and earthquake data recorded at 1316 seismic stations, the largest number used for the region to date. More than 700,000 dispersion curves were measured to generate group and phase velocity maps at periods of 10-140s. The resolution of our model is significantly improved over previous models with about 1-2°in eastern China and 2-3°in western China. We also derived models of the study region for crustal thickness and averaged S velocities for upper and mid-lower crust and uppermost mantle. These models reveal important lithospheric features beneath China and provide a fundamental data set for understanding continental dynamics and evolution. Different geological units show distinct features in the Moho depth, lithospheric thickness, and shear velocity. In particular, the North China Craton (NCC) lithosphere shows strong east-west structural variations with thin and low-velocity lithosphere in eastern NCC and thick and high-velocity lithosphere beneath western NCC and the lithosphere of the Ordos Block seems to have undergone strong erosion. The results support the progressive destruction of the NCC lithosphere from east to west at least partly caused by the thermal-chemical erosion of the cratonic lithosphere from the asthenosphere. Another pronounced feature of our model is the strong lateral variations of the mantle lithosphere beneath the Tibetan Plateau (TP). The Indian lithosphere beneath the TP shows variable northward advancement with nearly flat subduction in western and eastern TP and steep subduction in central TP with evidence for the tearing of Indian lithosphere beneath central TP, which may be important for the riftings at the surface in Himalayas and southern TP. The low-velocity zone in northern TP shows strong correlation with the region of the mid-Miocene to Quaternary potassic

  4. A high resolution model of linear trend in mass variations from DMT-2: Added value of accounting for coloured noise in GRACE data

    Science.gov (United States)

    Farahani, Hassan H.; Ditmar, Pavel; Inácio, Pedro; Didova, Olga; Gunter, Brian; Klees, Roland; Guo, Xiang; Guo, Jing; Sun, Yu; Liu, Xianglin; Zhao, Qile; Riva, Riccardo

    2017-01-01

    We present a high resolution model of the linear trend in the Earth's mass variations based on DMT-2 (Delft Mass Transport model, release 2). DMT-2 was produced primarily from K-Band Ranging (KBR) data of the Gravity Recovery And Climate Experiment (GRACE). It comprises a time series of monthly solutions complete to spherical harmonic degree 120. A novel feature in its production was the accurate computation and incorporation of stochastic properties of coloured noise when processing KBR data. The unconstrained DMT-2 monthly solutions are used to estimate the linear trend together with a bias, as well as annual and semi-annual sinusoidal terms. The linear term is further processed with an anisotropic Wiener filter, which uses full noise and signal covariance matrices. Given the fact that noise in an unconstrained model of the trend is reduced substantially as compared to monthly solutions, the Wiener filter associated with the trend is much less aggressive compared to a Wiener filter applied to monthly solutions. Consequently, the trend estimate shows an enhanced spatial resolution. It allows signals in relatively small water bodies, such as Aral sea and Ladoga lake, to be detected. Over the ice sheets, it allows for a clear identification of signals associated with some outlet glaciers or their groups. We compare the obtained trend estimate with the ones from the CSR-RL05 model using (i) the same approach based on monthly noise covariance matrices and (ii) a commonly-used approach based on the DDK-filtered monthly solutions. We use satellite altimetry data as independent control data. The comparison demonstrates a high spatial resolution of the DMT-2 linear trend. We link this to the usage of high-accuracy monthly noise covariance matrices, which is due to an accurate computation and incorporation of coloured noise when processing KBR data. A preliminary comparison of the linear trend based on DMT-2 with that computed from GSFC_global_mascons_v01 reveals, among

  5. A New Switching-Based Median Filtering Scheme and Algorithm for Removal of High-Density Salt and Pepper Noise in Images

    Directory of Open Access Journals (Sweden)

    Jayaraj V

    2010-01-01

    Full Text Available A new switching-based median filtering scheme for restoration of images that are highly corrupted by salt and pepper noise is proposed. An algorithm based on the scheme is developed. The new scheme introduces the concept of substitution of noisy pixels by linear prediction prior to estimation. A novel simplified linear predictor is developed for this purpose. The objective of the scheme and algorithm is the removal of high-density salt and pepper noise in images. The new algorithm shows significantly better image quality with good PSNR, reduced MSE, good edge preservation, and reduced streaking. The good performance is achieved with reduced computational complexity. A comparison of the performance is made with several existing algorithms in terms of visual and quantitative results. The performance of the proposed scheme and algorithm is demonstrated.

  6. Experimental Demonstration of Ideal Noise Shaping in Resonant Tunneling Delta-Sigma Modulator for High Resolution, Wide Band Analog-to-Digital Converters

    Science.gov (United States)

    Maezawa, Koichi; Sakou, Mario; Matsubara, Wataru; Mizutani, Takashi; Matsuzaki, Hideaki

    2006-04-01

    A ΔΣ modulator using a frequency modulation intermediate signal was demonstrated using a resonant tunneling logic gate called a monostable bistable transition logic element (MOBILE). This ΔΣ modulator is based on the nature of an FM signal and suitable for high-speed operation. Experiments using an InP-based MOBILE demonstrate good noise shaping characteristics. Moreover, the operation with a higher FM carrier frequency than the sampling frequency was demonstrated, showing equally good noise shaping performance. This makes the design of the voltage-controlled oscillator, which is a key component of the FM ΔΣ modulator, much easier. Consequently, an FM ΔΣ modulator using MOBILE is promising for high-resolution, wide-band analog-to-digital converters (ADCs).

  7. Double-pass high-gain low-noise EDFA over S- and C+L-bands by tunable fundamental-mode leakage loss.

    Science.gov (United States)

    Hung, Chi-Ming; Chen, Nan-Kuang; Lai, Yinchieh; Chi, Sien

    2007-02-19

    We demonstrate a high-gain low-noise double-pass tunable EDFA over S- and C+L-bands by discretely introducing fundamental-mode leakage loss in a 16-m-long standard C-band Er(3+)-doped fiber. The amplified spontaneous emission at the wavelengths of longer than 1530 nm can be substantially attenuated by the ASE suppressing filters to maintain high population inversion and to squeeze out the optical gain for S-band signals. When the filters are disabled, the gain bandwidth immediately returns back to the C+L-bands. Under S-band operation, a 37 dB small signal gain and a minimum 4.84 dB noise figure at 1486.9 nm are achieved with a 980 nm pump power of 154 mW.

  8. Noise in Class AB translinear filter

    Energy Technology Data Exchange (ETDEWEB)

    Martini, G.; Svelto, V. [Pavia Univ. (Italy). Dip di Elettronica

    1998-07-01

    A specific statistical approach to describe the noise properties of non linear circuits is used. The noise properties of translinear filters operated in class AB are considered. This kind of filter has a dynamic range larger then the maximum signal to noise ratio, and exhibit signal to noise ratio saturation at high signal level. The paper shows how the noise properties depend on the circuit design parameters.

  9. A New Phase Noise Detection Method

    OpenAIRE

    Yan, Gangfeng

    2015-01-01

    Phase noise is one of the most important parameters in many oscillators. Detecting accurately phase noise for oscillators has importance significance. In this paper, based on correlation operation detection phase noise for oscillators was proposed. This method not only can save a high precision reference oscillator, but also can detect accurately the phase noise of measured oscillator in theory. Detected phase noise of oscillators using this method has very strong utility value.

  10. Iterative Algorithm for Removing Salt-pepper Noise From Highly Corrupted Images%图像高椒盐噪声的迭代滤除算法

    Institute of Scientific and Technical Information of China (English)

    李天翼; 王明辉; 袁培根; 刘新国

    2012-01-01

    为有效滤除图像中的高椒盐噪声,提出一种迭代滤波算法.首先采用极值方法检测出噪声点,然后对噪声点以迭代方式逐步滤波,直到噪声点全部清除.利用迭代方式中每一噪声点都能直接或间接利用到图像有用信息的特点,滤波输出始终采用恒定的3×3小邻域,避免了大邻域窗口的诸多弊端.基于图像相关特性,在滤波输出上采用一种基于灰度差的加权均值方式.仿真结果表明,该算法能有效滤除图像中的高椒盐噪声,性能优于其他许多同类算法.%An iterative filter algorithm is proposed to filter high density salt-pepper noise in images.It detects the noise pixel with minimum-maximum inspection,and then filters iteratively until all noise pixels are suppressed.To overcome the drawback of enlarged neighborhood,the algorithm takes a uniform 3×3 filtering window all the time,which ensures that all noise pixels be properly restored with enough information because of the trait of iterative manner.The output value is calculated using weighted mean based on each pixel's correlation with the filtering pixel.Compared with other methods,simulation results show that the proposed algorithm gives better signal-to-noise ratios(SNR) and more satisfactory images.

  11. 发动机声激励下的车内高频噪声分析%Vehicle Interior High Frequency Noise under Engine Acoustic Excitation

    Institute of Scientific and Technical Information of China (English)

    杜爱民; 邵长慧; 邵建旺; 魏娜

    2016-01-01

    In order to research the vehicle interior high frequency noise and the performance of sound package under the engine acoustic excitation ,the statistical energy analysis and sound package models were built with VA One software .Both the power-based noise reduction test and the engine noise measurement were conducted to verify the accuracy of vehicle model .The cowl panel and floor were identified to be the main noise transfer paths according to the energy contribution of driver head and leg a-coustic cavity ,which laid the foundation for the optimization of sound package and the control of vehicle interior noise in the fu-ture .%为研究发动机声激励下中高频噪声和整车声学包隔声性能,在VA One软件中建立整车统计能量分析模型和声学包模型,并进行基于能量的整车隔声量测试和发动机噪声采集试验,验证了整车模型的准确性.通过对驾驶员头部声腔和腿部声腔的输入能量贡献量分析,发现前围和地板是车内噪声的主要传播路径,为后续汽车声学包的优化设计和车内噪声控制提供了帮助.

  12. Noise factor of a high-speed cinematography system; Facteur de bruit d'une chaine de cinematographie ultrarapide: application a la fusion par confinement inertiel

    Energy Technology Data Exchange (ETDEWEB)

    Secroun, A

    2000-03-01

    Inertial confinement fusion simulates in a laboratory the thermodynamic state of the center of stars, thus leading to the determination of stellar parameters. In order to reach that aim, high-speed cinematography brings up instruments specifically adapted to picosecond measurement, for which it is necessary to know the final precision. A model of the noise factor of the instruments under study is introduced and confronted to the experimental results obtained. (authors)

  13. The subjective importance of noise spectral content

    Science.gov (United States)

    Baxter, Donald; Phillips, Jonathan; Denman, Hugh

    2014-01-01

    This paper presents secondary Standard Quality Scale (SQS2) rankings in overall quality JNDs for a subjective analysis of the 3 axes of noise, amplitude, spectral content, and noise type, based on the ISO 20462 softcopy ruler protocol. For the initial pilot study, a Python noise simulation model was created to generate the matrix of noise masks for the softcopy ruler base images with different levels of noise, different low pass filter noise bandwidths and different band pass filter center frequencies, and 3 different types of noise: luma only, chroma only, and luma and chroma combined. Based on the lessons learned, the full subjective experiment, involving 27 observers from Google, NVIDIA and STMicroelectronics was modified to incorporate a wider set of base image scenes, and the removal of band pass filtered noise masks to ease observer fatigue. Good correlation was observed with the Aptina subjective noise study. The absence of tone mapping in the noise simulation model visibly reduced the contrast at high levels of noise, due to the clipping of the high levels of noise near black and white. Under the 34-inch viewing distance, no significant difference was found between the luma only noise masks and the combined luma and chroma noise masks. This was not the intuitive expectation. Two of the base images with large uniform areas, `restaurant' and `no parking', were found to be consistently more sensitive to noise than the texture rich scenes. Two key conclusions are (1) there are fundamentally different sensitivities to noise on a flat patch versus noise in real images and (2) magnification of an image accentuates visual noise in a way that is non-representative of typical noise reduction algorithms generating the same output frequency. Analysis of our experimental noise masks applied to a synthetic Macbeth ColorChecker Chart confirmed the color-dependent nature of the visibility of luma and chroma noise.

  14. 高速列车车头的气动噪声数值分析%Numerical Analysis on Aerodynamic Noise of the High-speed Train Head

    Institute of Scientific and Technical Information of China (English)

    刘加利; 张继业; 张卫华

    2011-01-01

    Along with the raising of the train speed, aerodynamic noise of the high-speed train are generated more and more significantly and their reduction has become one of the key factors to control noises of the highspeed train. In this paper, aerodynamic noise radiated from the high-speed train head surface are analyzed numerically. The mathematical and physical models of the three dimensional flow field of the high-speed train are established and the external steady and unsteady flow fields of the high-speed train are calculated by using the standard k-e turbulence model and large eddy simulation (LES) respectively. On the basis of the steady flow field, aerodynamic noise sources on the car body surface of the high-speed train are calculated by using the broadband noise source model. On the basis of the unsteady flow field, the time domain and frequency domain characteristics of fluctuating pressures on the car body surface are analyzed. The far-field aerodynamic noise of the high-speed train are calculated by applying the Lighthill acoustic analogue theory and the time domain and frequency domain characteristics of aerodynamic noise in the far-field are analyzed. The computational research is significant to study and control of aerodynamic noise of the high-speed train.%随着列车运行速度的提高,列车气动噪声变得越来越明显,降低气动噪声已成为控制高速列车噪声的关键之一.本文对高速列车车头气动噪声进行数值分析.首先,建立高速列车三维绕流流场的数学物理模型,分别利用标准k-ε湍流模型和大涡模拟计算高速列车的外部稳态和瞬态流场.然后,基于稳态流场,利用宽频带噪声源模型计算高速列车车身表面气动噪声源;基于瞬态流场,分析车身表面脉动压力的时域及频域特性;利用Lighthill声学比拟理论,计算高速列车远场气动噪声,分析远场气动噪声的时域及频域特性.本文对研究和控制高速列车气动噪声具有一定意义.

  15. Equivalent noise level response to number of vehicles: a comparison between a high traffic flow and low traffic flow highway in Klang Valley, Malaysia

    OpenAIRE

    Halim, Herni; Abdullah, Ramdzani

    2014-01-01

    HIGHLIGHTS Highway traffic noise is a serious problem in Malaysia Heavy traffic flow highway recorded higher noise level compared to low traffic flow Noise level stabilized at certain number of vehicles on the road i.e above 500 vehicles. Although much research on road traffic noise has found that noise level increase are influenced by driver behavior and source-receiver distance, little attention has been paid to the relationship between noise level and total number of vehicles...

  16. Noise impact on population along Beij ing-Shanghai high-speed railway%京沪高铁运营对沿线人群噪声影响

    Institute of Scientific and Technical Information of China (English)

    田丰; 毕军

    2014-01-01

    为研究高速铁路噪声对沿线人群的干扰,了解主要影响时段分布特点及主要影响特征,为高铁噪声治理及沿线土地利用规划和声功能区划提供建议,以入户面对面调查的方式对高铁沿线200 m范围内的居民进行了随机不重复抽样调查,建立了高铁噪声暴露声级-影响主观感受关系模型。研究表明,高铁沿线居民受高铁噪声影响最大时段为20:00~22:00,且影响时段与睡眠关系密切,沿线居民受此影响,睡眠质量明显下降,影响程度与所处暴露声级水平呈正向相关关系。在对不同高铁噪声暴露声级下的声环境宜居性进行分析的基础上,提出了高铁沿线土地利用规划和声功能区划控制建议。%In order to study the noise impacts of high-speed railways on people living along the railway lines,to com-prehend the distribution features of the main affecting time as well as the main affecting characteristics,to offer sug-gestions on noise controlling,land utilizing and acoustic-function dividing,a face-to-face survey was randomly conducted among people within a living area of 200 meters along the railway lines.Hence a relationship model, namely noise exposure level-impact subj ective feel,was established.The results showed that residents along the high-speed railways were most affected by noises between 20:00 and 22:00,a period closely related to sleeping.Under this influence,man's sleeping quality was sharply reducing and that degree of influence has a positive correlation with the noise exposure level.Based on analysis of acoustic-environment-livability under exposure levels of different high-speed noises,proposals of land utilizing and acoustic-function dividing along railway lines were put forward.

  17. Development of Active Noise Control System for Quieting Transformer Noise

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Development of Active Noise Control System for Quieting Transformer Noise

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Prevalence of high frequency hearing loss consistent with noise exposure among people working with sound systems and general population in Brazil: A cross-sectional study

    Directory of Open Access Journals (Sweden)

    Trevisani Virgínia FM

    2008-05-01

    Full Text Available Abstract Background Music is ever present in our daily lives, establishing a link between humans and the arts through the senses and pleasure. Sound technicians are the link between musicians and audiences or consumers. Recently, general concern has arisen regarding occurrences of hearing loss induced by noise from excessively amplified sound-producing activities within leisure and professional environments. Sound technicians' activities expose them to the risk of hearing loss, and consequently put at risk their quality of life, the quality of the musical product and consumers' hearing. The aim of this study was to measure the prevalence of high frequency hearing loss consistent with noise exposure among sound technicians in Brazil and compare this with a control group without occupational noise exposure. Methods This was a cross-sectional study comparing 177 participants in two groups: 82 sound technicians and 95 controls (non-sound technicians. A questionnaire on music listening habits and associated complaints was applied, and data were gathered regarding the professionals' numbers of working hours per day and both groups' hearing complaint and presence of tinnitus. The participants' ear canals were visually inspected using an otoscope. Hearing assessments were performed (tonal and speech audiometry using a portable digital AD 229 E audiometer funded by FAPESP. Results There was no statistically significant difference between the sound technicians and controls regarding age and gender. Thus, the study sample was homogenous and would be unlikely to lead to bias in the results. A statistically significant difference in hearing loss was observed between the groups: 50% among the sound technicians and 10.5% among the controls. The difference could be addressed to high sound levels. Conclusion The sound technicians presented a higher prevalence of high frequency hearing loss consistent with noise exposure than did the general population, although

  20. Prevalence of high frequency hearing loss consistent with noise exposure among people working with sound systems and general population in Brazil: a cross-sectional study.

    Science.gov (United States)

    El Dib, Regina P; Silva, Edina M K; Morais, José F; Trevisani, Virgínia F M

    2008-05-07

    Music is ever present in our daily lives, establishing a link between humans and the arts through the senses and pleasure. Sound technicians are the link between musicians and audiences or consumers. Recently, general concern has arisen regarding occurrences of hearing loss induced by noise from excessively amplified sound-producing activities within leisure and professional environments. Sound technicians' activities expose them to the risk of hearing loss, and consequently put at risk their quality of life, the quality of the musical product and consumers' hearing. The aim of this study was to measure the prevalence of high frequency hearing loss consistent with noise exposure among sound technicians in Brazil and compare this with a control group without occupational noise exposure. This was a cross-sectional study comparing 177 participants in two groups: 82 sound technicians and 95 controls (non-sound technicians). A questionnaire on music listening habits and associated complaints was applied, and data were gathered regarding the professionals' numbers of working hours per day and both groups' hearing complaint and presence of tinnitus. The participants' ear canals were visually inspected using an otoscope. Hearing assessments were performed (tonal and speech audiometry) using a portable digital AD 229 E audiometer funded by FAPESP. There was no statistically significant difference between the sound technicians and controls regarding age and gender. Thus, the study sample was homogenous and would be unlikely to lead to bias in the results. A statistically significant difference in hearing loss was observed between the groups: 50% among the sound technicians and 10.5% among the controls. The difference could be addressed to high sound levels. The sound technicians presented a higher prevalence of high frequency hearing loss consistent with noise exposure than did the general population, although the possibility of residual confounding due to unmeasured factors

  1. Monitoring of Noise During Ganeshotsav

    Directory of Open Access Journals (Sweden)

    Mrs. P. Saler

    2011-09-01

    Full Text Available Sound is a form of energy emitted by a vibrating body causing change in pressure of the surrounding elastic medium through which energy is transmitted. Noise has been defined as unwanted sound. Noise is a disturbance to the human environment which is escalating at a high rate. There are numerous effects of noise on human and environment due to the increase in noise pollution slowly, insensibly; we seem to accept noise and the physiological and psychological deterioration that accompanies it as an inevitable part of our lives. Althoughattempts have been made to regulate noise pollution by setting standards for some of the major sources of noise, we often are unable to monitor them. One such source of noise in India is celebration of festival and especially in Maharashtra, the biggest festival- Ganeshostav. The way noise levels are increasing year by year during this festival, it seems we enjoy these sounds, though it has harmful effects on Human Health and Environment. This paper focuses on study of noise pollution during Ganesh Festival and also its other causes and effects.

  2. Switching bilateral filter with a texture/noise detector for universal noise removal.

    Science.gov (United States)

    Lin, Chih-Hsing; Tsai, Jia-Shiuan; Chiu, Ching-Te

    2010-09-01

    In this paper, we propose a switching bilateral filter (SBF) with a texture and noise detector for universal noise removal. Operation was carried out in two stages: detection followed by filtering. For detection, we propose the sorted quadrant median vector (SQMV) scheme, which includes important features such as edge or texture information. This information is utilized to allocate a reference median from SQMV, which is in turn compared with a current pixel to classify it as impulse noise, Gaussian noise, or noise-free. The SBF removes both Gaussian and impulse noise without adding another weighting function. The range filter inside the bilateral filter switches between the Gaussian and impulse modes depending upon the noise classification result. Simulation results show that our noise detector has a high noise detection rate as well as a high classification rate for salt-and-pepper, uniform impulse noise and mixed impulse noise. Unlike most other impulse noise filters, the proposed SBF achieves high peak signal-to-noise ratio and great image quality by efficiently removing both types of mixed noise, salt-and-pepper with uniform noise and salt-and-pepper with Gaussian noise. In addition, the computational complexity of SBF is significantly less than that of other mixed noise filters.

  3. Characterization of a Low-phase-noise, High-power (370 mW), External-Cavity Semiconductor Laser

    Science.gov (United States)

    2010-07-21

    oise (H z/H z 1/2) 1/f noise white noise (a...P ha se n oi se (μ ra d- 1 m /r t(H z) ) S 1/2 ν (f):Frequency N oise (H z/H z 1/2) 100 101 102 103 104 105 106 107 10-3 10-2 10-1 100 101 102...n oi se (μ ra d- 1 m /r t(H z) ) Frequency (Hz) S 1/2 ν (f):Frequency N oise (H z/H z 1/2) (b) P ha se n oi se (μ ra d- 1 m /r t(H z) ) S

  4. A low-noise high dynamic-range time-domain EMI measurement system for CISPR Band E

    Science.gov (United States)

    Hoffmann, C.; Russer, P.

    2011-08-01

    In this paper, a broadband time-domain EMI measurement system for measurements from 9 kHz to 18 GHz is presented that allows for compliant EMI measurements in CISPR Band E. Combining ultra-fast analog-to-digital-conversion and real-time digital signal processing on a field-programmable-gate-array (FPGA) with ultra-broadband multi-stage down-conversion, scan times can be reduced by several orders of magnitude in comparison to a traditional heterodyne EMI-receiver. The ultra-low system noise floor of 6-8 dB and the real-time spectrogram allow for the characterisation of the time-behaviour of EMI near the noise floor. EMI measurements of electronic consumer devices and electric household appliances are presented.

  5. Evaluation of a Cubature Kalman Filtering-Based Phase Unwrapping Method for Differential Interferograms with High Noise in Coal Mining Areas

    Directory of Open Access Journals (Sweden)

    Wanli Liu

    2015-07-01

    Full Text Available Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced to unwrap differential interferograms with high noise in mining areas. It can perform simultaneous noise filtering and phase unwrapping so that the pre-filtering steps can be omitted, thus usually retaining more details and improving the detectable deformation. For the method, the nonlinear measurement model of phase unwrapping is processed using a simplified Cubature Kalman filtering, which is an effective and efficient tool used in many nonlinear fields. Three case studies are designed to evaluate the performance of the method. In Case 1, two tests are designed to evaluate the performance of the method under different factors including the number of multi-looks and path-guiding indexes. The result demonstrates that the unwrapped results are sensitive to the number of multi-looks and that the Fisher Distance is the most suitable path-guiding index for our study. Two case studies are then designed to evaluate the feasibility of the proposed phase unwrapping method based on Cubature Kalman filtering. The results indicate that, compared with the popular Minimum Cost Flow method, the Cubature Kalman filtering-based phase unwrapping can achieve promising results without pre-filtering and is an appropriate method for coal mining areas with high noise.

  6. Evaluation of a Cubature Kalman Filtering-Based Phase Unwrapping Method for Differential Interferograms with High Noise in Coal Mining Areas.

    Science.gov (United States)

    Liu, Wanli; Bian, Zhengfu; Liu, Zhenguo; Zhang, Qiuzhao

    2015-07-06

    Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced to unwrap differential interferograms with high noise in mining areas. It can perform simultaneous noise filtering and phase unwrapping so that the pre-filtering steps can be omitted, thus usually retaining more details and improving the detectable deformation. For the method, the nonlinear measurement model of phase unwrapping is processed using a simplified Cubature Kalman filtering, which is an effective and efficient tool used in many nonlinear fields. Three case studies are designed to evaluate the performance of the method. In Case 1, two tests are designed to evaluate the performance of the method under different factors including the number of multi-looks and path-guiding indexes. The result demonstrates that the unwrapped results are sensitive to the number of multi-looks and that the Fisher Distance is the most suitable path-guiding index for our study. Two case studies are then designed to evaluate the feasibility of the proposed phase unwrapping method based on Cubature Kalman filtering. The results indicate that, compared with the popular Minimum Cost Flow method, the Cubature Kalman filtering-based phase unwrapping can achieve promising results without pre-filtering and is an appropriate method for coal mining areas with high noise.

  7. Low noise road surfaces

    OpenAIRE

    Bolčina, Matjaž

    2014-01-01

    Noise is everywhere. Noise is a sound that makes people stressful and irritate. It often couses sleep disorders and also health problems like different cardiovascular disorders, hearing loss…In most cases traffic noise is the most disturbing. There are different ways to prevent people from traffic noise like building noise barriers and insulation of facades. However noise barriers and insulation of facades do not prevent noise formation, but are lowering existing noise. Another disadvantage i...

  8. Road Traffic Noise

    Science.gov (United States)

    Beckenbauer, Thomas

    Road traffic is the most interfering noise source in developed countries. According to a publication of the European Union (EU) at the end of the twentieth century [1], about 40% of the population in 15 EU member states is exposed to road traffic noise at mean levels exceeding 55 dB(A). Nearly 80 million people, 20% of the population, are exposed to levels exceeding 65 dB(A) during daytime and more than 30% of the population is exposed to levels exceeding 55 dB(A) during night time. Such high noise levels cause health risks and social disorders (aggressiveness, protest, and helplessness), interference of communication and disturbance of sleep; the long- and short-term consequences cause adverse cardiovascular effects, detrimental hormonal responses (stress hormones), and possible disturbance of the human metabolism (nutrition) and the immune system. Even performance at work and school could be impaired.

  9. Noise and Tinnitus

    Directory of Open Access Journals (Sweden)

    Mansoureh Adel Ghahraman

    1999-03-01

    Full Text Available Tinnitus from the Latin word tinnire meaning ringing is the perception of sound within the human ear in the absence of corresponding external sound. The most common cause is noise induced hearing loss. Tinnitus may be induced by an acoustic trauma or a permanent noise in the workplace. In case that Tinnitus is induced by acoustic trauma the site of lesion is commonly the base of the cochlea. Tinnitus in the senile population is mostly accompanying presbycusis. Although the incidence of permanent tinnitus following noise exposure is high, little is published about this issue. In the current article we are aimed at studying the prevalence of tinnitus in Minoo and other manufactures.

  10. Using rapid assessment to evaluate noise on an in-patient unit.

    Science.gov (United States)

    Deitrick, Lynn M; Kennedy, Paulette; Cyriax, Carol; Davies-Hathen, Nancy

    2009-01-01

    Rapid assessment was used to evaluate a noise problem on a busy, high-traffic, high-acuity medical/surgical telemetry unit over a 4-week period. Six sources of environmental noise were identified including conversational noise, noise from doors, noise from housekeeping activities, noise from the pneumatic message tube station, hallway noise, and miscellaneous noise. Our study also demonstrates the value of rapid-assessment methodology for the evaluation of clinical problems such as noise.

  11. Design of high-resolution and multilevel reference pattern for improvement of both light utilization efficiency and signal-to-noise ratio in coaxial holographic data storage.

    Science.gov (United States)

    Nobukawa, Teruyoshi; Nomura, Takanori

    2014-06-10

    A high-resolution and multilevel designed reference pattern (DRP) is presented for improvement of both light utilization efficiency and the signal-to-noise ratio (SNR) of reconstructed images in coaxial holographic data storage. With a DRP, the desired Fourier power spectrum of a reference beam is obtained. Numerical and experimental results show that the DRP increases the SNR compared with that of a random phase mask (RPM). Moreover, the light utilization efficiency of the DRP is higher than that of a high-resolution RPM. In addition, the effect of the phase level and the pixel pitch of DRPs on the SNR and the light utilization efficiency are investigated.

  12. Divide and conquer spot noise

    NARCIS (Netherlands)

    Leeuw, W.C. de; Liere, R. van

    1997-01-01

    The design and implementation of an interactive spot noise algorithm is presented. Spot noise is a technique which utilizes texture for the visualization of flow fields. Various design tradeoffs are discussed that allow an optimal implementation on a range of high end graphical workstations. Two app

  13. Identification and Reduction of Turbomachinery Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Communities near airports are often exposed to high noise levels due to low flying aircraft in the takeoff and landing phases of flight. Propulsion source noise is...

  14. Behavioural Models for Common Mode EMI Filters

    NARCIS (Netherlands)

    Roc'h, A.

    2012-01-01

    EMC is defined as the “ability of an equipment or system to function satisfactorily in its electromagnetic environment without producing intolerable electromagnetic disturbances to anything in that environment‿. EMC means that equipment shall be designed and manufactured, in such way that: - The

  15. Improved stochastic resonance algorithm for enhancement of signal-to-noise ratio of high-performance liquid chromatographic signal

    Energy Technology Data Exchange (ETDEWEB)

    Xie Shaofei [Center for Instrumental Analysis, China Pharmaceutical University, Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China); Xiang Bingren [Center for Instrumental Analysis, China Pharmaceutical University, Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China)]. E-mail: cpuxsf@hotmail.com; Deng Haishan [Center for Instrumental Analysis, China Pharmaceutical University, Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China); Xiang Suyun [Center for Instrumental Analysis, China Pharmaceutical University, Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China); Lu Jun [Center for Instrumental Analysis, China Pharmaceutical University, Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China)

    2007-02-28

    Based on the theory of stochastic resonance, an improved stochastic resonance algorithm with a new criterion for optimizing system parameters to enhance signal-to-noise ratio (SNR) of HPLC/UV chromatographic signal for trace analysis was presented in this study. Compared with the conventional criterion in stochastic resonance, the proposed one can ensure satisfactory SNR as well as good peak shape of chromatographic peak in output signal. Application of the criterion to experimental weak signals of HPLC/UV was investigated and the results showed an excellent quantitative relationship between different concentrations and responses.

  16. A low noise, high thermal stability, 0.1 K test facility for the Planck HFI bolometers

    OpenAIRE

    2002-01-01

    We are developing a facility which will be used to characterize the bolometric detectors for Planck, an ESA mission to investigate the Cosmic Microwave Background. The bolometers operate at 0.1 K, employing neutron-transmutation doped (NTD) Ge thermistors with resistances of several megohms to achieve NEPs~1×10^(–17) W Hz^(–1/2). Characterization of the intrinsic noise of the bolometers at frequencies as low as 0.010 Hz dictates a test apparatus thermal stability of 40 nK Hz^(–1/2) to that fr...

  17. High Velocity Jet Noise Source Location and Reduction. Task 3 - Experimental Investigation of Suppression Principles. Volume I. Suppressor Concepts Optimization

    Science.gov (United States)

    1978-12-01

    noise to the far field. This is shown by the work of Eldred (26); Middleton and Clark (27); Gray, Gutierrez , and Walker (28); the Boeing Company (2, 5...coo * . . ,.0 0 0 00 __ __ _ -4 Z cc 0 0 e4 co* 4) 0-4 u fa V)~- 960 Ix 0 -4) 0 -0 14 0 x t • .0,04 0 , _ __ o- 0 CID - 97 L. 0’. •;" 0".:- ] .• •-4...Engines, March 1974. 16. Olsen, W.A., Gutierrez , O.A., and Dorsch, R.G., "The Effect of Nozzle Inlet Shape, Lip Thickness, and Exit Shape and Size on

  18. A low-noise wide-dynamic-range event-driven detector using SOI pixel technology for high-energy particle imaging

    Science.gov (United States)

    Shrestha, Sumeet; Kamehama, Hiroki; Kawahito, Shoji; Yasutomi, Keita; Kagawa, Keiichiro; Takeda, Ayaki; Tsuru, Takeshi Go; Arai, Yasuo

    2015-08-01

    This paper presents a low-noise wide-dynamic-range pixel design for a high-energy particle detector in astronomical applications. A silicon on insulator (SOI) based detector is used for the detection of wide energy range of high energy particles (mainly for X-ray). The sensor has a thin layer of SOI CMOS readout circuitry and a thick layer of high-resistivity detector vertically stacked in a single chip. Pixel circuits are divided into two parts; signal sensing circuit and event detection circuit. The event detection circuit consisting of a comparator and logic circuits which detect the incidence of high energy particle categorizes the incident photon it into two energy groups using an appropriate energy threshold and generate a two-bit code for an event and energy level. The code for energy level is then used for selection of the gain of the in-pixel amplifier for the detected signal, providing a function of high-dynamic-range signal measurement. The two-bit code for the event and energy level is scanned in the event scanning block and the signals from the hit pixels only are read out. The variable-gain in-pixel amplifier uses a continuous integrator and integration-time control for the variable gain. The proposed design allows the small signal detection and wide dynamic range due to the adaptive gain technique and capability of correlated double sampling (CDS) technique of kTC noise canceling of the charge detector.

  19. Noise Pollution and Health Effects

    Directory of Open Access Journals (Sweden)

    Geravandi

    2015-01-01

    Full Text Available Background Noise pollution is of particular importance due to the physical and psychological effects on humans. Noise is a stressor that affects the autonomic nervous system and the endocrine system. Noise is also a threat to marine and terrestrial ecosystems. Health risks from noise are correlated with road traffic. In other words, noise health effects are the health consequences of elevated sound levels. Objectives This study aims to determine the effect of noise pollution (near roadways on health issues in Ahvaz, Iran. Materials and Methods In this cross-sectional study, equivalent sound pressure level were measured by sound level meters TES-1353 in 75 locations around 4 roadways, which had a high load of traffic in Ahvaz City during day time. During the study, 820 measurements were recorded at measuring stations, for 7 days per week with 1-hour interval between each measurement. Statistical analysis was carried out by SPSS software. Results According to the research findings, the equivalent sound pressure levels in all stations were 76.28 ± 3.12 dB (Mean ± SD. According to sound measurements and the survey questionnaire, noise pollution is higher than EPA (US Environmental Protection Agency and Iran standard level. Based on result of this study the worst noise health effects were the nervousness and sleep quality during 2012. Conclusions According to the results of this study, with increasing load of traffic, there is an increasing need for proper consideration plans to control noise pollution and prevent its effects.

  20. Noise Effects in the Mode-Locked External Cavity Lasers

    Institute of Scientific and Technical Information of China (English)

    Nuran Dogru; M. Sadettin Ozyazici

    2003-01-01

    Effect of high level of spontaneous and carrier noise on mode-locked hybrid soliton pulse source and relative intensity noise is described. Transform limited pulses are not generated over a wide frequency range because of these noises.

  1. A high signal-to-noise ratio passive near-field microscope equipped with a helium-free cryostat

    Science.gov (United States)

    Lin, Kuan-Ting; Komiyama, Susumu; Kim, Sunmi; Kawamura, Ken-ichi; Kajihara, Yusuke

    2017-01-01

    We have developed a passive long-wavelength infrared (LWIR) scattering-type scanning near-field optical microscope (s-SNOM) installed in a helium-free mechanically cooled cryostat, which facilitates cooling of an LWIR detector and optical elements to 4.5 K. To reduce mechanical vibration propagation from a compressor unit, we have introduced a metal bellows damper and a helium gas damper. These dampers ensure the performance of the s-SNOM to be free from mechanical vibration. Furthermore, we have introduced a solid immersion lens to improve the confocal microscope performance. To demonstrate the passive s-SNOM capability, we measured thermally excited surface evanescent waves on Au/SiO2 gratings. A near-field signal-to-noise ratio is 4.5 times the improvement with an acquisition time of 1 s/pixel. These improvements have made the passive s-SNOM a more convenient and higher-performance experimental tool with a higher signal-to-noise ratio for a shorter acquisition time of 0.1 s.

  2. Unified aeroacoustics analysis for high speed turboprop aerodynamics and noise. Volume 2: Development of theory for wing shielding

    Science.gov (United States)

    Amiet, R. K.

    1991-01-01

    A unified theory for aerodynamics and noise of advanced turboprops is presented. The theory and a computer code developed for evaluation at the shielding benefits that might be expected by an aircraft wing in a wing-mounted propeller installation are presented. Several computed directivity patterns are presented to demonstrate the theory. Recently with the advent of the concept of using the wing of an aircraft for noise shielding, the case of diffraction by a surface in a flow has been given attention. The present analysis is based on the case of diffraction of no flow. By combining a Galilean and a Lorentz transform, the wave equation with a mean flow can be reduced to the ordinary equation. Allowance is also made in the analysis for the case of a swept wing. The same combination of Galilean and Lorentz transforms lead to a problem with no flow but a different sweep. The solution procedures for the cases of leading and trailing edges are basically the same. Two normalizations of the solution are given by the computer program. FORTRAN computer programs are presented with detailed documentation. The output from these programs compares favorably with the results of other investigators.

  3. A high signal-to-noise ratio passive near-field microscope equipped with a helium-free cryostat.

    Science.gov (United States)

    Lin, Kuan-Ting; Komiyama, Susumu; Kim, Sunmi; Kawamura, Ken-Ichi; Kajihara, Yusuke

    2017-01-01

    We have developed a passive long-wavelength infrared (LWIR) scattering-type scanning near-field optical microscope (s-SNOM) installed in a helium-free mechanically cooled cryostat, which facilitates cooling of an LWIR detector and optical elements to 4.5 K. To reduce mechanical vibration propagation from a compressor unit, we have introduced a metal bellows damper and a helium gas damper. These dampers ensure the performance of the s-SNOM to be free from mechanical vibration. Furthermore, we have introduced a solid immersion lens to improve the confocal microscope performance. To demonstrate the passive s-SNOM capability, we measured thermally excited surface evanescent waves on Au/SiO2 gratings. A near-field signal-to-noise ratio is 4.5 times the improvement with an acquisition time of 1 s/pixel. These improvements have made the passive s-SNOM a more convenient and higher-performance experimental tool with a higher signal-to-noise ratio for a shorter acquisition time of 0.1 s.

  4. A high-resolution tunneling magneto-resistance sensor interface circuit

    Science.gov (United States)

    Li, Xiangyu; Yin, Liang; Chen, Weiping; Gao, Zhiqiang; Liu, Xiaowei

    2017-02-01

    In this paper, a chopper instrumentation amplifier and a high-precision and low-noise CMOS band gap reference in a standard 0.5 μm CMOS technology for a tunneling magneto-resistance (TMR) sensor is presented. The noise characteristic of TMR sensor is an important factor in determining the performance of the sensor. In order to obtain a larger signal to noise ratio (SNR), the analog front-end chip ASIC weak signal readout circuit of the sensor includes the chopper instrumentation amplifier; the high-precision and low-noise CMOS band gap reference. In order to achieve the low noise, the chopping technique is applied in the first stage amplifier. The low-frequency flicker noise is modulated to high-frequency by chopping switch, so that the modulator has a better noise suppression performance at the low frequency. The test results of interface circuit are shown as below: At a single 5 V supply, the power dissipation is 40 mW; the equivalent offset voltage is less than 10 uV; the equivalent input noise spectral density 30 nV/Hz1/2(@10 Hz), the equivalent input noise density of magnetic is 0.03 nTHz1/2(@10 Hz); the scale factor temperature coefficient is less than 10 ppm/∘C, the equivalent input offset temperature coefficient is less than 70 nV/∘C; the gain error is less than 0.05%, the common mode rejection ratio is greater than 120 dB, the power supply rejection ratio is greater than 115 dB; the nonlinear is 0.1% FS.

  5. Road-Traffic Noise: Annoyance, Risk Perception, and Noise Sensitivity in the Finnish Adult Population

    Science.gov (United States)

    Okokon, Enembe Oku; Turunen, Anu W.; Ung-Lanki, Sari; Vartiainen, Anna-Kaisa; Tiittanen, Pekka; Lanki, Timo

    2015-01-01

    Exposure to road-traffic noise commonly engenders annoyance, the extent of which is determined by factors not fully understood. Our aim was to estimate the prevalence and determinants of road-traffic noise annoyance and noise sensitivity in the Finnish adult population, while comparing the perceptions of road-traffic noise to exhausts as environmental health problems. Using a questionnaire that yielded responses from 1112 randomly selected adult Finnish respondents, we estimated road-traffic noise- and exhausts-related perceived exposures, health-risk perceptions, and self-reported annoyance on five-point scales, while noise sensitivity estimates were based on four questions. Determinants of noise annoyance and sensitivity were investigated using multivariate binary logistic regression and linear regression models, respectively. High or extreme noise annoyance was reported by 17% of respondents. Noise sensitivity scores approximated a Gaussian distribution. Road-traffic noise and exhausts were, respectively, considered high or extreme population-health risks by 22% and 27% of respondents. Knowledge of health risks from traffic noise, OR: 2.04 (1.09–3.82) and noise sensitivity, OR: 1.07 (1.00–1.14) were positively associated with annoyance. Knowledge of health risks (p traffic noise, and perceive it to be a significant health risk, almost comparable to traffic exhausts. There is no distinct noise-sensitive population subgroup. Knowledge of health risks of road-traffic noise, and attitudinal variables are associated with noise annoyance and sensitivity. PMID:26016432

  6. Adaptive Noise Reduction Scheme for Salt and Pepper

    CERN Document Server

    Gebreyohannes, Tina

    2012-01-01

    In this paper, a new adaptive noise reduction scheme for images corrupted by impulse noise is presented. The proposed scheme efficiently identifies and reduces salt and pepper noise. MAG (Mean Absolute Gradient) is used to identify pixels which are most likely corrupted by salt and pepper noise that are candidates for further median based noise reduction processing. Directional filtering is then applied after noise reduction to achieve a good tradeoff between detail preservation and noise removal. The proposed scheme can remove salt and pepper noise with noise density as high as 90% and produce better result in terms of qualitative and quantitative measures of images.

  7. Experimental study of a high speed quantum random number generation scheme based on measuring phase noise of a single mode laser

    CERN Document Server

    Qi, Bing; Lo, Hoi-Kwong; Qian, Li

    2009-01-01

    In this paper, we present a high speed random number generation scheme based on measuring the quantum phase noise of a single mode diode laser operating at a low intensity level near the lasing threshold. A delayed self-heterodyning system has been developed to measure the random phase fluctuation. We experimentally investigate this random number generation scheme under two different operating conditions: with or without active phase stabilization of the fiber interferometer in the self-heterodyning system. The achieved random number generation rates are 500Mbit/s and 50Mbit/s, respectively. The generated random numbers have passed all the DIEHARD tests.

  8. Active Noise Control of Radiated Noise from Jets Originating NASA

    Science.gov (United States)

    Doty, Michael J.; Fuller, Christopher R.; Schiller, Noah H.; Turner, Travis L.

    2013-01-01

    The reduction of jet noise using a closed-loop active noise control system with highbandwidth active chevrons was investigated. The high frequency energy introduced by piezoelectrically-driven chevrons was demonstrated to achieve a broadband reduction of jet noise, presumably due to the suppression of large-scale turbulence. For a nozzle with one active chevron, benefits of up to 0.8 dB overall sound pressure level (OASPL) were observed compared to a static chevron nozzle near the maximum noise emission angle, and benefits of up to 1.9 dB OASPL were observed compared to a baseline nozzle with no chevrons. The closed-loop actuation system was able to effectively reduce noise at select frequencies by 1-3 dB. However, integrated OASPL did not indicate further reduction beyond the open-loop benefits, most likely due to the preliminary controller design, which was focused on narrowband performance.

  9. Measures Study and Effect Analysis of Noise Reduction for High Speed Inspection Train%高速综合检测列车降噪措施研究与效果分析

    Institute of Scientific and Technical Information of China (English)

    张丽荣; 张志军; 王东川

    2011-01-01

    This paper shows the example of noise control measures for 400 km/h high speed inspection train and presents the measures study and effect analysis of noise reduction for high speed inspection train. Based on analyzing the source noise of high speed inspection train, aiming at reduce the source noise and noise path controlling technique, we used such noising reduction method as high damping on car body, sound insulation and absorbing material in equipment cabin, damping treatment in air condition tube and noise absorbing material in brake unit to reduce the sound pressure level in the train. The static and dynamic test results of the train shows that the noise reduction measures have reached the noise reduction target well. The sound pressure has been controlled bellow 68dB successfully.%以400 km/h高速综合检测列车噪声控制措施为例,在分析高速检测车的噪声来源的基础上,针对噪声产生的根源和有关噪声控制技术,分别采取车体高阻尼减震、设备舱隔音吸音、空调管路阻尼处理、制动单元吸音处理等降噪措施来降低车内噪声.从高速综合检测列车在静止状态和运行状态下的测试结果分析,针对车内采取的降噪措施,达到了预期的隔音降噪效果,整车声压值水平控制在68 dB以内.

  10. Interior High Frequency Noise Analysis of Heavy Vehicle Cab and Multi-Objective Optimization with Statistical Energy Analysis Method

    Science.gov (United States)

    Chen, Shuming; Wang, Lianhui; Song, Jiqang; Wang, Dengfeng; Chen, Jing

    The interior sound pressure levels of a commercial vehicle cab at the driver’s right ear position and head rest position are determined as evaluation indices of vehicle acoustic performances. A statistical energy analysis model of the commercial vehicle cab was created by using statistical energy analysis method. The simulated interior acoustic performance of the cab has a significant coincidence with the experimental results. A response surface model was presented to determine the relationship between sound package parameters and evaluation indices of the interior acoustic performance for the vehicle cab. A multi-objective optimization was performed by using NSGA II algorithm with weighting coefficient method. The presented method provides a new idea for the multi-objective optimization design of the acoustic performances in vehicle noise analysis and control field.

  11. High-Speed Vessel Noises in West Hong Kong Waters and Their Contributions Relative to Indo-Pacific Humpback Dolphins (Sousa chinensis

    Directory of Open Access Journals (Sweden)

    Paul Q. Sims

    2012-01-01

    Full Text Available The waters of West Hong Kong are home to a population of Indo-Pacific humpback dolphins (Sousa chinensis that use a variety of sounds to communicate. This area is also dominated by intense vessel traffic that is believed to be behaviorally and acoustically disruptive to dolphins. While behavioral changes have been documented, acoustic disturbance has yet to be shown. We compared the relative sound contributions of various high-speed vessels to nearby ambient noise and dolphin social sounds. Ambient noise levels were also compared between areas of high and low traffic. We found large differences in sound pressure levels between high traffic and no traffic areas, suggesting that vessels are the main contributors to these discrepancies. Vessel sounds were well within the audible range of dolphins, with sounds from 315–45,000 Hz. Additionally, vessel sounds at distances ≥100 m exceeded those of dolphin sounds at closer distances. Our results reaffirm earlier studies that vessels have large sound contributions to dolphin habitats, and we suspect that they may be inducing masking effects of dolphin sounds at close distances. Further research on dolphin behavior and acoustics in relation to vessels is needed to clarify impacts.

  12. 一种高电源抑制比低噪声的带隙基准源%A High Power Supply Rejection Ratio Low Noise Voltage Reference

    Institute of Scientific and Technical Information of China (English)

    张涛; 陈远龙; 王影; 张国俊

    2016-01-01

    基于SMIC 0.18μm CMOS工艺,设计了一种高电源抑制比低噪声的带隙基准源。此电路在3.3V电源电压下具有较好的温度系数,-40℃~125℃范围内的温度系数为8.6 ppm/℃,带隙基准电路输出电压约为1.195V。通过在基准中运放加入电源抑制比增强级电路提高中低频范围PSRR性能,在电路输出端再引入低通滤波器电路以提高中高频范围PSRR性能,并且低通滤波器有助于降低整个电路的噪声。采用Spectre软件进行仿真,结果显示,电源抑制比为-130.4@dc,-77.6@100KHz,输出噪声为24.8nV@100KHz。该带隙基准源电路非常适合于应用在高电源电压抑制比、低噪声的LDO电路中。%Based on SMIC 0.18μm CMOS process, a high power supply rejection ratio (PSRR) low noise bandgap voltage reference was designed. The temperature coefficient of this circuit achieved 8.6ppm/℃ in the -40℃~125℃ temperature range when the input voltage was 3.3V, and the output voltage of the bandgap reference circuit wad 1.195V. A PSRR enhance stage was inserted into op-amp to enhance PSRR in low frequency range, and low pass filter was inserted in voltage reference to improve PSRR performance in high frequency range, besides the low pass filter was helpful to reduce noise of the whole circuit. The circuit was simulated with Spectre software. Simulation results showed that the PSRR was -130.4dB at dc and -77.6dB at 100KHz respectively, and output noise at 100KHz was 24.8nV. The bandgap voltage reference circuit was suitable for the high PSRR and low noise LDO.

  13. Urban background noise mapping: the general model

    NARCIS (Netherlands)

    Wei, W.; Botteldooren, D.; Renterghem, T. van; Hornikx, M.; Forssen, J.; Salomons, E.; Ogren, M.

    2014-01-01

    Surveys show that inhabitants of dwellings exposed to high noise levels benefit from having access to a quiet side. However, current practice in noise prediction often underestimates the noise levels at a shielded façade. Multiple reflections between façades in street canyons and inner yards are com

  14. Noise Analysis of Switched-Current Circuits

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur

    1999-01-01

    The understanding of noise in analog sampled data systems is vital for the design of high resolution circuitry in the discrete time domain. In this paper a general description of sampled and held noise is presened. The noise calculations are verified by measurements on an analog delay line implem...

  15. Noise Analysis of Switched-Current Circuits

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur

    1998-01-01

    The understanding of noise in analog sampled data systems is vital for the design of high resolution circuitry. In this paper a general description of sampled and held noise is presented. The noise calculations are verified by measurements on an analog delay line implemented using switched-curren...

  16. Sampled Noise in Switched Current Circuits

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Herald Holger; Bogason, Gudmundur

    1997-01-01

    The understanding of noise in analog sampled data systems is vital for the design of high resolution circuitry. In this paper a general description of sampled and held noise is presented. The noise calculations are verified by measurements on an analog delay line implemented using switched-current...

  17. Urban background noise mapping: the general model

    NARCIS (Netherlands)

    Wei, W.; Botteldooren, D.; Renterghem, T. van; Hornikx, M.; Forssen, J.; Salomons, E.; Ogren, M.

    2014-01-01

    Surveys show that inhabitants of dwellings exposed to high noise levels benefit from having access to a quiet side. However, current practice in noise prediction often underestimates the noise levels at a shielded façade. Multiple reflections between façades in street canyons and inner yards are com

  18. A flexible and high-performance bidirectional optical amplifier with all optical gain control using ASE noise path through multi-port circulators

    Institute of Scientific and Technical Information of China (English)

    An Vu Tran; Chang-Joon Chae; Rodney S. Tucker

    2003-01-01

    We report a flexible all-optical gain controlled bidirectional optical amplifier. The device achieves constant gain and low noise figure over a large input power range. Moreover, the device removes Rayleigh backscattered light and amplifier noise.

  19. Bipartite output consensus in networked multi-agent systems of high-order power integrators with signed digraph and input noises

    Science.gov (United States)

    Ma, Hongwen; Liu, Derong; Wang, Ding; Luo, Biao

    2016-10-01

    In this paper, we concentrate on investigating bipartite output consensus in networked multi-agent systems of high-order power integrators. Systems with power integrator are ubiquitous among weakly coupled, unstable and underactuated mechanical systems. In the presence of input noises, an adaptive disturbance compensator and a technique of adding power integrator are introduced to the complex nonlinear multi-agent systems to reduce the deterioration of system performance. Additionally, due to the existence of negative communication weights among agents, whether bipartite output consensus of high-order power integrators can be achieved remains unknown. Therefore, it is of great importance to study this issue. The underlying idea of designing the distributed controller is to combine the output information of each agent itself and its neighbours, the state feedback within its internal system and input adaptive noise compensator all together. When the signed digraph is structurally balanced, bipartite output consensus can be reached. Finally, numerical simulations are provided to verify the validity of the developed criteria.

  20. Signal to Noise Ratio Characterization of Coherent Doppler Lidar Backscattered Signals

    Directory of Open Access Journals (Sweden)

    Abdelazim Sameh

    2016-01-01

    Full Text Available An eye-safe coherent Doppler Lidar (CDL system for wind measurement was developed and tested at the Remote Sensing Laboratory of the City College of New York (CCNY. The system employs a 1542 nm fiber laser to leverage components’ availability and affordability of the telecommunication industry. A balanced detector with a bandwidth extending from dc to 125 MHz is used to eliminate the common mode relative intensity noise (RIN. The system is shot noise limited i.e., the dominant component of received signals’ noise is the shot noise. Wind velocity can be measured under nominal aerosol loading and atmospheric turbulence conditions for ranges up to 3 km while pointing vertically with 0.08 m/s precision.