WorldWideScience

Sample records for active noise control

  1. Active noise control primer

    CERN Document Server

    Snyder, Scott D

    2000-01-01

    Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications. The aim of this book is to present all of the basic knowledge one needs for assessing how useful active noise control will be for a given problem and then to provide some guidance for designing, setting up, and tuning an active noise-control system. Written for students who have no prior knowledge of acoustics, signal processing, or noise control but who do have a reasonable grasp of basic physics and mathematics, the book is short and descriptive. It leaves for more advanced texts or research monographs all mathematical details and proofs concerning vibrations, signal processing and the like. The book can thus be used in independent study, in a classroom with laboratories, or in conjunction with a kit for experiment or demonstration. Topics covered include: basic acoustics; human perception and sound; sound intensity...

  2. Active Noise Control for Dishwasher noise

    Science.gov (United States)

    Lee, Nokhaeng; Park, Youngjin

    2016-09-01

    The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.

  3. 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.

  4. 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.

  5. 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.

  6. Developing active noise control systems for noise attenuation in ducts

    Science.gov (United States)

    Campos, Rosely V.; Ivo, Rodrigo C.; Medeiros, Eduardo B.

    2002-11-01

    The present work describes some of the research effort on Active Noise Control (ANC) being jointly developed by the Catholic University of Minas Gerais (PUC-MINAS) and the Federal University of Minas Gerais (UFMG). Considerations about the implementation of Digital Signal Processing for noise control in ducts has been presented. The objective is to establish a study on Active Noise Control in ducts combining geometry and acoustic parameters modification together with adaptive digital filtering implementation. Both algorithm and digital signal processing details are also discussed. The main results for a typical application where real attenuation has been obtained are presented and considered according to their use in developing real applications. The authors also believe that the present text should provide an interesting overview for both designers and students concerned about Active Noise Control in ducts. (To be presented in Portuguese.)

  7. Active Noise Control for Vehicle Exhaust Noise Reduction

    Institute of Scientific and Technical Information of China (English)

    李克强; 杨殿阁; 郑四发; 连小珉; 田中丈晴

    2003-01-01

    An active noise control (ANC) method was developed for exhaust noise reduction for medium-duty diesel trucks. A modified variable step size least mean squares (LMS) algorithm was used for the controller in a variable environment that considered the vehicle's acceleration characteristics. The variable step size time-based synchronized filtered-x LMS method (SFX-TB) used an adaptive algorithm that was more efficient than the conventional filtered-x LMS algorithm. The simulation and the experimental tests show that the control trackability and stability provided by the algorithm during acceleration enable the ANC system to effectively reduce the vehicle exhaust noise.

  8. Active Control of Fan Noise

    Institute of Scientific and Technical Information of China (English)

    Nobuhiko YAMASAKI; Hirotoshi TAJIMA

    2008-01-01

    In the wake-rotor interaction fan noise, a number of the interacting modes at the blade passing frequency (BPF)and its harmonics are generated which are prescribed by the number of stator and rotor blades etc. In the present study, the dominant mode is tried to be suppressed by the secondary sound from the loudspeaker actuators. One of the novel features of the present system is the adoption of the control board with the Field Programmable Gate Array (FPGA) hardware and the LabVIEW software to synchronize the circumferentially installed loudspeaker actuators with the relative location of rotational blades under arbitrary fan rotational speeds. The experiments were conducted under the conditions of three rotational speeds of 2004, 3150, and 4002 [rpm]. The reduction in the sound pressure level (SPL) was observed for all three rotational speeds. The sound pressure level at the BPF was reduced approximately 13 [dB] for 2004 [rpm] case, but not so large reduction was attained for other cases probably due to the inefficiency of the loudspeaker actuators at high frequencies

  9. The application of active noise control technology to reduce noise from air pollution control equipment

    Energy Technology Data Exchange (ETDEWEB)

    Depies, C. R.; Kapsos, D. W.

    1996-08-01

    The basic concept of active noise control, i. e. to create a noise field in a space in order to destructively interfere with an existing noise, and in the process create a quieter space, was explained. The manner in which noise control technology can be used in air pollution control equipment was described and guidelines for application were provided. A number of case studies were used to illustrate the suitability of active noise control for low frequency noise problems, especially in the area of air pollution control equipment. Impressive reduction of low frequency noise, energy efficiency, ability to retrofit into an existing duct system, and the hardware`s insensitivity to dirty exhaust environments were cited as the principal reasons for the success of active noise control technology over more traditional in-line passive silencers. 1 ref., 8 figs.

  10. Automotive active noise control (ANC) system. Jidoshayo active noise control (ANC) system

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, S. (Nissan Motor Co. Ltd., Tokyo (Japan))

    1992-11-25

    This paper introduces a successful development of an active noise control (ANC) system that selects and controls noise in an automobile compartment. This is a system that Nissan has developed for practical use for the first time in the world by using an adaptive control theory and a digital signal processor (DSP) that uses ultra-high speed operating elements. The principle for noise silencing in the ANC system utilizes interference of cyclic amplitude of sound with opposite phase. Sounds in an automobile include informative sounds, agreeable sounds, and noise, and combinations of these sounds work complexly on people in a car, of which extent varies depending on individuals. The adaptive control minimizes sounds picked up by a microphone into controlled speaker sound via an multiple error filtered algorithm (MEF-[sub X]LMS) and an adaptive digital filter. Major components of the system include a microphone, a speaker, and a control unit (comprising the adaptive algorithm and the adaptive filter), all having been developed newly. A DSP that operates on ultra-high speed operating elements was used for speedy compliance with complex algorithms, so that the controlled sound combined of engine noise with compartment sound field can be calculated. The noise was reduced by more than 10 dB at maximum. 7 figs.

  11. Active Aircraft Pylon Noise Control System

    Science.gov (United States)

    Thomas, Russell H. (Inventor); Czech, Michael J. (Inventor); Elmiligui, Alaa A. (Inventor)

    2017-01-01

    An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.

  12. Active noise control technology. Active soon seigyo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Eguchi, M.; Kokubo, F.; Tanaka, S.; Yao, K. (Sharp Corp., Osaka (Japan))

    1994-05-10

    The signal processing method of the Active Noise Control (ANC) system was studied. The principle of ANC is to output secondary sound waves having opposite phase, identical amplitude from the control point of the sound wave of the primary sound source, and eliminate the noise by interference. As application fields, there are air conditioner ducts and compressors as one dimensional noise source, and automobile and axial fan as three dimensional noise source. In order to improve the stability of coefficient renewal algorithm of Adaptive Digital Filter (ADF), for generation of opposite phase noise, DC-LMS algorithm which can control the rise in gain of specified frequency zone was proposed. Furthermore, with the purpose of reducing the amount of operation, the introduction of lattice type AR filter was tested for the stability of the filter in IIR-ADF (Infinite Impulse Response Adaptive Digital Filter) and its application process. The applicability studies of these improved methods on the noise inside of ducts were actually measured, and the effect was verified. For the multi-channel control of 3 dimensional noise source, reference scanning method to reduce the filter operation was proposed. In the partial space noise eliminating experiment, it was made clear that it possesses equivalent effect to error scanning method. 11 refs., 14 figs., 1 tab.

  13. Active Noise Control of the Heavy Truck Interior Cab

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to control the noise of the heavy truck interior cab effectively, the active noise control methods are employed. First, an interior noise field test for the heavy truck is performed, and frequencies of interior noise of this vehicle are analyzed. According to the spectrum analysis of acquired noise signal, it is found out that the main frequencies of interior noise are less than 800Hz. Then the least squares lattice (LSL) algorithm is used as signal processing algorithm of the controller and a closed-loop control DSP system, based on TMS 320VC5416, is developed. The residual signal at driver's ear is used as feedback signal. Lastly, the developed ANC system is loaded into the heavy truck cab, and controlling the noise at driver's ear for that truck at different driving speeds is attempted. The noise control test results indicate that the cab interior noise is reduced averagely by 0.9 dBA at different driving speeds.

  14. On-line Monitoring and Active Control for Transformer Noise

    Science.gov (United States)

    Liang, Jiabi; Zhao, Tong; Tian, Chun; Wang, Xia; He, Zhenhua; Duan, Lunfeng

    This paper introduces the system for on-line monitoring and active noise control towards the transformer noise based on LabVIEW and the hardware equipment including the hardware and software. For the hardware part, it is mainly focused on the composition and the role of hardware devices, as well as the mounting location in the active noise control experiment. And the software part introduces the software flow chats, the measurement and analysis module for the sound pressure level including A, B, C weighting methods, the 1/n octave spectrum and the power spectrum, active noise control module and noise data access module.

  15. Active Noise Feedback Control Using a Neural Network

    Directory of Open Access Journals (Sweden)

    Zhang Qizhi

    2001-01-01

    Full Text Available The active noise control (ANC is discussed. Many digital ANC systems often based on the filter-x algorithm for finite impulse response (FIR filter use adaptive filtering techniques. But if the primary noise path is nonlinear, the control system based on adaptive filter technology will be invalid. In this paper, an adaptive active nonlinear noise feedback control approach using a neural network is derived. The feedback control system drives a secondary signal to destructively interfere with the original noise to cut down the noise power. An on-line learning algorithm based on the error gradient descent method was proposed, and the local stability of closed loop system is proved using the discrete Lyapunov function. A nonlinear simulation example shows that the adaptive active noise feedback control method based on a neural network is very effective to the nonlinear noise control.

  16. Active noise control: A tutorial for HVAC designers

    Energy Technology Data Exchange (ETDEWEB)

    Gelin, L.J.

    1997-08-01

    This article will identify the capabilities and limitations of ANC in its application to HVAC noise control. ANC can be used in ducted HVAC systems to cancel ductborne, low-frequency fan noise by injecting sound waves of equal amplitude and opposite phase into an air duct, as close as possible to the source of the unwanted noise. Destructive interference of the fan noise and injected noise results in sound cancellation. The noise problems that it solves are typically described as rumble, roar or throb, all of which are difficult to address using traditional noise control methods. This article will also contrast the use of active against passive noise control techniques. The main differences between the two noise control measures are acoustic performance, energy consumption, and design flexibility. The article will first present the fundamentals and basic physics of ANC. The application to real HVAC systems will follow.

  17. Active Noise Feedback Control Using a Neural Network

    OpenAIRE

    Zhang Qizhi; Jia Yongle

    2001-01-01

    The active noise control (ANC) is discussed. Many digital ANC systems often based on the filter-x algorithm for finite impulse response (FIR) filter use adaptive filtering techniques. But if the primary noise path is nonlinear, the control system based on adaptive filter technology will be invalid. In this paper, an adaptive active nonlinear noise feedback control approach using a neural network is derived. The feedback control system drives a secondary signal to destructively interfere with ...

  18. Mechanisms of active control for noise inside a vibrating cylinder

    Science.gov (United States)

    Lester, Harold C.; Fuller, Chris R.

    1987-01-01

    The active control of propeller-induced noise fields inside a flexible cylinder is studied with attention given to the noise reduction mechanisms inherent in the present coupled acoustic shell model. The active noise control model consists of an infinitely long aluminum cylinder with a radius of 0.4 m and a thickness of 0.001 m. Pressure maps are shown when the two external sources are driven in-phase at a frequency corresponding to Omega = 0.22.

  19. Active noise control: a review of the field.

    Science.gov (United States)

    Gordon, R T; Vining, W D

    1992-11-01

    Active noise control (ANC) is the application of the principle of the superposition of waves to noise attenuation problems. Much progress has been made toward applying ANC to narrow-band, low-frequency noise in confined spaces. During this same period, the application of ANC to broad-band noise or noise in three-dimensional spaces has seen little progress because of the recent quantification of serious physical limitations, most importantly, noncausality, stability, spatial mismatch, and the infinite gain controller requirement. ANC employs superposition to induce destructive interference to affect the attenuation of noise. ANC was believed to utilize the mechanism of phase cancellation to achieve the desired attenuation. However, current literature points to other mechanisms that may be operating in ANC. Categories of ANC are one-dimensional field and duct noise, enclosed spaces and interior noise, noise in three-dimensional spaces, and personal hearing protection. Development of active noise control stems from potential advantages in cost, size, and effectiveness. There are two approaches to ANC. In the first, the original sound is processed and injected back into the sound field in antiphase. The second approach is to synthesize a cancelling waveform. ANC of turbulent flow in pipes and ducts is the largest area in the field. Much work into the actual mechanism involved and the causal versus noncausal aspects of system controllers has been done. Fan and propeller noise can be divided into two categories: noise generated directly as the blade passing tones and noise generated as a result of blade tip turbulence inducing vibration in structures. Three-dimensional spaces present a noise environment where physical limitations are magnified and the infinite gain controller requirement is confronted. Personal hearing protection has been shown to be best suited to the control of periodic, low-frequency noise.

  20. Numerical evaluation of the performance of active noise control systems

    Science.gov (United States)

    Mollo, C. G.; Bernhard, R. J.

    1990-01-01

    This paper presents a generalized numerical technique for evaluating the optimal performance of active noise controllers. In this technique, the indirect BEM numerical procedures are used to derive the active noise controllers for optimal control of enclosed harmonic sound fields where the strength of the noise sources or the description of the enclosure boundary may not be known. The performance prediction for a single-input single-output system is presented, together with the analysis of the stability and observability of an active noise-control system employing detectors. The numerical procedures presented can be used for the design of both the physical configuration and the electronic components of the optimal active noise controller.

  1. Novel active noise-reducing headset using earshell vibration control.

    Science.gov (United States)

    Rafaely, Boaz; Carrilho, Joao; Gardonio, Paolo

    2002-10-01

    Active noise-reducing (ANR) headsets are available commercially in applications varying from aviation communication to consumer audio. Current ANR systems use passive attenuation at high frequencies and loudspeaker-based active noise control at low frequencies to achieve broadband noise reduction. This paper presents a novel ANR headset in which the external noise transmitted to the user's ear via earshell vibration is reduced by controlling the vibration of the earshell using force actuators acting against an inertial mass or the earshell headband. Model-based theoretical analysis using velocity feedback control showed that current piezoelectric actuators provide sufficient force but require lower stiffness for improved low-frequency performance. Control simulations based on experimental data from a laboratory headset showed that good performance can potentially be achieved in practice by a robust feedback controller, while a single-frequency real-time control experiment verified that noise reduction can be achieved using earshell vibration control.

  2. Binaural Integrated Active Noise Control and Noise Reduction in Hearing Aids

    DEFF Research Database (Denmark)

    Serizel, Romain; Moonen, Marc; Wouters, Jan;

    2013-01-01

    This paper presents a binaural approach to integrated active noise control and noise reduction in hearing aids and aims at demonstrating that a binaural setup indeed provides significant advantages in terms of the number of noise sources that can be compensated for and in terms of the causality...

  3. Perception Neural Networks for Active Noise Control Systems

    Directory of Open Access Journals (Sweden)

    Wang Xiaoli

    2012-11-01

    Full Text Available In a response to a growing demand for environments of 70dB or less noise levels, many industrial sectors have focused with some form of noise control system. Active noise control (ANC has proven to be the most effective technology. This paper mainly investigates application of neural network on self-adaptation system in active noise control (ANC. An active silencing control system is made which adopts a motional feedback loudspeaker as not a noise controlling source but a detecting sensor. The working fundamentals and the characteristics of the motional feedback loudspeaker are analyzed in detail. By analyzing each acoustical path, identification based adaptive linear neural network is built. This kind of identifying method can be achieved conveniently. The estimated result of each sound channel matches well with its real sound character, respectively.

  4. Foundations of Active Control - Active Noise Reduction Helmets

    DEFF Research Database (Denmark)

    Elmkjær, Torsten Haaber Leth

    2008-01-01

    This Ph.D. thesis includes fundamental considerations about topologies, algorithms, implementations, methods etc., that can enter in the next generation of active control (AC) systems. Specifically, a new variant of feedforward control referred to as confined feedforward active control (CFFAC......-output (MIMO) system that facilitates both feedforward and feedback control. The general system is then referred to as hybrid MIMO confined-feedforward feedback (HMIMOCFFFB) active noise reduction (ANR) system. The investigation of a multi-channel ANR system with hybrid feedforward and feedback topologies...... be computational intensive takes place at an even slower sampling rate hereby relaxing the requirements on a high bandwidth. It is demonstrated that computational savings as high as 40% can be achieved in a 192, 24, 3 kHz triple-rate system as compared with a 24 kHz single-rate system without sacrificing the ANR...

  5. Active noise control in fuselage design

    NARCIS (Netherlands)

    Krakers, L.A.; Tooren, M.J.L. van; Beukers, A.; Berkhof, A.P.; Goeje, M.P. de

    2003-01-01

    To achieve comfortable noise levels inside the passenger cabin, sound damping measures have to be taken to improve the sound insulation properties of the bare airframe. Usually the sound insulation requirements of a passenger cabin are met after the mechanical design of the fuselage structure is alr

  6. Active noise control using noise source having adaptive resonant frequency tuning through stiffness variation

    Science.gov (United States)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by a plurality of force transmitting mechanisms which contact the noise radiating element. Each one of the force transmitting mechanisms includes an expandable element and a spring in contact with the noise radiating element so that excitation of the element varies the spring force applied to the noise radiating element. The elements are actuated by a controller which receives input of a signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the elements and causes the spring force applied to the noise radiating element to be varied. The force transmitting mechanisms can be arranged to either produce bending or linear stiffness variations in the noise radiating element.

  7. Development of a Voice Activity Controlled Noise Canceller

    Directory of Open Access Journals (Sweden)

    Aini Hussain

    2012-05-01

    Full Text Available In this paper, a variable threshold voice activity detector (VAD is developed to control the operation of a two-sensor adaptive noise canceller (ANC. The VAD prohibits the reference input of the ANC from containing some strength of actual speech signal during adaptation periods. The novelty of this approach resides in using the residual output from the noise canceller to control the decisions made by the VAD. Thresholds of full-band energy and zero-crossing features are adjusted according to the residual output of the adaptive filter. Performance evaluation of the proposed approach is quoted in terms of signal to noise ratio improvements as well mean square error (MSE convergence of the ANC. The new approach showed an improved noise cancellation performance when tested under several types of environmental noise. Furthermore, the computational power of the adaptive process is reduced since the output of the adaptive filter is efficiently calculated only during non-speech periods.

  8. Multichannel active noise control systems and algorithms for reduction on broadband noise

    NARCIS (Netherlands)

    Berkhoff, A.P.; Wesselink, J.M.

    2007-01-01

    Active noise contral systems for braadband noise reduction require substantial computing power, especially for multichannel systems and adaptive controllers. Furthermore, speed of convergence can be an issue as weil. In this paper, methods and techniques are described that are able to reduce the com

  9. Quelling Cabin Noise in Turboprop Aircraft via Active Control

    Science.gov (United States)

    Kincaid, Rex K.; Laba, Keith E.; Padula, Sharon L.

    1997-01-01

    Cabin noise in turboprop aircraft causes passenger discomfort, airframe fatigue, and employee scheduling constraints due to OSHA standards for exposure to high levels of noise. The noise levels in the cabins of turboprop aircraft are typically 10 to 30 decibels louder than commercial jet noise levels. However. unlike jet noise the turboprop noise spectrum is dominated by a few low frequency tones. Active structural acoustic control is a method in which the control inputs (used to reduce interior noise) are applied directly to a vibrating structural acoustic system. The control concept modeled in this work is the application of in-plane force inputs to piezoceramic patches bonded to the wall of a vibrating cylinder. The goal is to determine the force inputs and locations for the piezoceramic actuators so that: (1) the interior noise is effectively damped; (2) the level of vibration of the cylinder shell is not increased; and (3) the power requirements needed to drive the actuators are not excessive. Computational experiments for data taken from a computer generated model and from a laboratory test article at NASA Langley Research Center are provided.

  10. Active control of aerodynamic noise; Active control ni yoru furyoku soon no seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, M. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1996-10-01

    This paper introduces summary and examples of active noise control (ANC) and active flow control (AFC) as the aerodynamic noise control techniques. The ANC is a technique to generate noise of a reverse phase which cancels the original noise. Noise reduced especially effectively by the ANC is noise from fans and ducts used for engine air supply and exhaust. The ANC is effective in low frequencies, and when used with a passive method, a compact exhaust silencer can be realized, which has high noise reducing performance over the whole frequency band and has low pressure loss. Signal processing in active noise reduction system is always so adjusted that noise is discharged from a secondary noise source in which signals detected by a detection microphone is given a digital filter treatment, and output from an error microphone is minimized. The AFC has been incapable of realizing a reverse phase over a wide frequency band when depended on analog treatment. However, the authors have developed an adaptive type feedback control system, and verified that the system can be applied to any frequency variation and control it in a stable manner. 15 refs., 9 figs., 1 tab.

  11. Active noise control using noise source having adaptive resonant frequency tuning through stress variation

    Science.gov (United States)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by an expandable ring embedded in the noise radiating element. Excitation of the ring causes expansion or contraction of the ring, thereby varying the stress in the noise radiating element. The ring is actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the ring, causing the ring to expand or contract. Instead of a single ring embedded in the noise radiating panel, a first expandable ring can be bonded to one side of the noise radiating element, and a second expandable ring can be bonded to the other side.

  12. Hybrid Active Noise Control using Adjoint LMS Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Hyun Do; Hong, Sik Ki [Dankook University (Korea, Republic of)

    1998-07-01

    A multi-channel hybrid active noise control(MCHANC) is derived by combining hybrid active noise control techniques and adjoint LMS algorithms, and this algorithm is applied to an active noise control system in a three dimensional enclosure. A MCHANC system uses feed forward and feedback filters simultaneously to cancel noises in an enclosure. The adjoint LMs algorithm, in which the error is filtered through an adjoint filter of the secondary channel, is also used to reduce the computational burden of adaptive filters. The overall attenuation performance and convergence characteristics of MCHANC algorithm is better than both multiple-channel feed forward algorithms and multiple-channel feedback algorithms. In a large enclosure, the acoustic reverberation can be very long, which means a very high order feed forward filter must be used to cancel the reverberation noises. Strong reverberation noises are generally narrow band and low frequency, which can be effectively predicted and canceled by a feedback adaptive filters. So lower order feed forward filter taps can be used in MCHANC algorithm which combines advantages of fast convergence and small excess mean square error. In this paper, computer simulations and real time implementations is carried out on a TMS320C31 processor to evaluate the performance of the MCHANC systems. (author). 11 refs., 11 figs., 1 tab.

  13. Applications of active adaptive noise control to jet engines

    Science.gov (United States)

    Shoureshi, Rahmat; Brackney, Larry

    1993-01-01

    During phase 2 research on the application of active noise control to jet engines, the development of multiple-input/multiple-output (MIMO) active adaptive noise control algorithms and acoustic/controls models for turbofan engines were considered. Specific goals for this research phase included: (1) implementation of a MIMO adaptive minimum variance active noise controller; and (2) turbofan engine model development. A minimum variance control law for adaptive active noise control has been developed, simulated, and implemented for single-input/single-output (SISO) systems. Since acoustic systems tend to be distributed, multiple sensors, and actuators are more appropriate. As such, the SISO minimum variance controller was extended to the MIMO case. Simulation and experimental results are presented. A state-space model of a simplified gas turbine engine is developed using the bond graph technique. The model retains important system behavior, yet is of low enough order to be useful for controller design. Expansion of the model to include multiple stages and spools is also discussed.

  14. Active noise control using noise source having adaptive resonant frequency tuning through variable ring loading

    Science.gov (United States)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of noise radiating structure is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating structure is tuned by a plurality of drivers arranged to contact the noise radiating structure. Excitation of the drivers causes expansion or contraction of the drivers, thereby varying the edge loading applied to the noise radiating structure. The drivers are actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the drivers, causing them to expand or contract. The noise radiating structure may be either the outer shroud of the engine or a ring mounted flush with an inner wall of the shroud or disposed in the interior of the shroud.

  15. First Test of Fan Active Noise Control (ANC) Completed

    Science.gov (United States)

    2005-01-01

    With the advent of ultrahigh-bypass engines, the space available for passive acoustic treatment is becoming more limited, whereas noise regulations are becoming more stringent. Active noise control (ANC) holds promise as a solution to this problem. It uses secondary (added) noise sources to reduce or eliminate the offending noise radiation. The first active noise control test on the low-speed fan test bed was a General Electric Company system designed to control either the exhaust or inlet fan tone. This system consists of a "ring source," an induct array of error microphones, and a control computer. Fan tone noise propagates in a duct in the form of spinning waves. These waves are detected by the microphone array, and the computer identifies their spinning structure. The computer then controls the "ring source" to generate waves that have the same spinning structure and amplitude, but 180 out of phase with the fan noise. This computer generated tone cancels the fan tone before it radiates from the duct and is heard in the far field. The "ring source" used in these tests is a cylindrical array of 16 flat-plate acoustic radiators that are driven by thin piezoceramic sheets bonded to their back surfaces. The resulting source can produce spinning waves up to mode 7 at levels high enough to cancel the fan tone. The control software is flexible enough to work on spinning mode orders from -6 to 6. In this test, the fan was configured to produce a tone of order 6. The complete modal (spinning and radial) structure of the tones was measured with two builtin sets of rotating microphone rakes. These rakes provide a measurement of the system performance independent from the control system error microphones. In addition, the far-field noise was measured with a semicircular array of 28 microphones. This test represents the first in a series of tests that demonstrate different active noise control concepts, each on a progressively more complicated modal structure. The tests are

  16. A Review of Virtual Sensing Algorithms for Active Noise Control

    Directory of Open Access Journals (Sweden)

    Danielle Moreau

    2008-11-01

    Full Text Available Traditional local active noise control systems minimise the measured acoustic pressure to generate a zone of quiet at the physical error sensor location. The resulting zone of quiet is generally limited in size and this requires the physical error sensor be placed at the desired location of attenuation, which is often inconvenient. To overcome this, a number of virtual sensing algorithms have been developed for active noise control. Using the physical error signal, the control signal and knowledge of the system, these virtual sensing algorithms estimate the error signal at a location that is remote from the physical error sensor, referred to as the virtual location. Instead of minimising the physical error signal, the estimated error signal is minimised with the active noise control system to generate a zone of quiet at the virtual location. This paper will review a number of virtual sensing algorithms developed for active noise control. Additionally, the performance of these virtual sensing algorithms in numerical simulations and in experiments is discussed and compared.

  17. Concurrent mechatronic design approach for active control of cavity noise

    Science.gov (United States)

    de Oliveira, L. P. R.; da Silva, M. M.; Sas, P.; Van Brussel, H.; Desmet, W.

    2008-07-01

    Active control is a potential solution to many noise and vibration problems for improving the low-frequency performance. Cavity noise reduction as encountered for instance in aircraft cabins and vehicle interiors is a typical example. However, the conventional design of these active solutions may lead to suboptimal products, since the interaction between the vibro-acoustic plant dynamics and control dynamics is usually not considered. A proper way to design such active systems would be considering control and plant parameters concurrently. To cope with this approach, a methodology to derive a fully coupled mechatronic model that deals with both the vibro-acoustic plant dynamics as well as the control parameters is proposed. The inclusion of sensor and actuator models is investigated, since it contributes to the model accuracy as it can confer frequency, phase or amplitude limitations to the control performance. The proposed methodology provides a reduced state-space model derived from a fully coupled vibro-acoustic finite element model. Experimental data on a vibro-acoustic vehicle cabin mock-up are used to validate the model reduction procedure. Regarding noise reduction, optimization results are presented considering both vibro-acoustic plant features, such as thicknesses, and control parameters, such as sensor and actuator placement and control gains. A collocated sensor/actuator pair is considered in a velocity feedback control strategy. The benefits of a concurrent mechatronic design when dealing with active structural-acoustic control solutions are addressed, illustrated and experimentally validated.

  18. Multi-channel Kalman filters for active noise control

    NARCIS (Netherlands)

    Ophem, S. van; Berkhoff, A.P.

    2013-01-01

    By formulating the feed-forward broadband active noise control problem as a state estimation problem it is possible to achieve a faster rate of convergence than the filtered reference least mean squares algorithm and possibly also a better tracking performance. A multiple input/multiple output

  19. Multi-channel Kalman filters for active noise control

    NARCIS (Netherlands)

    van Ophem, S.; Berkhoff, Arthur P.

    By formulating the feed-forward broadband active noise control problem as a state estimation problem it is possible to achieve a faster rate of convergence than the filtered reference least mean squares algorithm and possibly also a better tracking performance. A multiple input/multiple output

  20. Active control of road booming noise in automotive interiors.

    Science.gov (United States)

    Oh, Shi-Hwan; Kim, Hyoun-suk; Park, Youngjin

    2002-01-01

    An active feedforward control system has been developed to reduce the road booming noise that has strong nonlinear characteristics. Four acceleration transducers were attached to the suspension system to detect reference vibration and two loudspeakers were used to attenuate the noise near the headrests of two front seats. A leaky constraint multiple filtered-X LMS algorithm with an IIR-based filter that has fast convergence speed and frequency selective controllability was proposed to increase the control efficiency in computing power and memory usage. During the test drive on the rough asphalt and turtle-back road at a constant speed of 60 km/h, we were able to achieve a reduction of around 6 dB of A-weighted sound pressure level in the road booming noise range with the proposed algorithm, which could not be obtained with the conventional multiple filtered-X LMS algorithm.

  1. Application of Feedforward Adaptive Active-Noise Control for Reducing Blade Passing Noise in Centrifugal Fans

    Science.gov (United States)

    WU, J.-D.; BAI, M. R.

    2001-02-01

    This paper describes two configurations of feedforward adaptive active-noise control (ANC) technique for reducing blade passing noise in centrifugal fans. In one configuration, the control speaker is installed at the cut-off region of the fan, while in the other configuration at the exit duct. The proposed ANC system is based on the filtered-x least-mean-squares (FXLMS) algorithm with multi-sine synthesized reference signal and frequency counting and is implemented by using a digital signal processor (DSP). Experiments are carried out to evaluate the proposed system for reducing the noise at the blade passing frequency (BPF) and its harmonics at various flow speeds. The results of the experiment indicated that the ANC technique is effective in reducing the blade passing noise for two configurations by using the feedforward adaptive control.

  2. Active noise control: A panacea for noise pollution. AntiGeluid: Een panacee tegen geluidsoverlast

    Energy Technology Data Exchange (ETDEWEB)

    Van den Dool, T.C. (Afdeling AntiGeluid, TNO Technisch Physische Dienst, Eindhoven (Netherlands))

    1994-09-01

    Active noise control (ANC) has a number of advantages compared to passive silencers, although it is not suitable for large noise pollution sources or large spaces, because many microphones, loudspeakers and much processing power is needed in these cases. ANC products include head sets, exhaust silencers, HVAC systems and systems for narrow enclosures with tonal noise pollution like cars and aeroplanes. The price of dedicated electronic systems is still decreasing which will positively affect the cost of ANC. 5 figs., 2 ills., 3 refs.

  3. Application of Adaptive Filters to Active Noise Control

    Institute of Scientific and Technical Information of China (English)

    PEI Bingnan; LI Chuanguang

    2001-01-01

    A modified LMS algorithm for noise-control is suggested after a mathematical model ofsound-cancellation is established, on the basis of thesound wave interference principle and the physicalmodel of progressive waves in a duct. Its applicationin controlling noise with the frequency range from 100to 800 Hz can be implemented by using the adaptivedigital signal processing technique. The experimentson a pink noise, a broadband noise and a noise takenfrom a tank were made, which show that there existsan attenuation of 11 dB at the frequency of 500 Hzor so, and that the proposed adaptive noise controltechnique is very effective and valid.

  4. Digitally controlled active noise reduction with integrated speech communication

    NARCIS (Netherlands)

    Steeneken, H.J.M.; Verhave, J.A.

    2004-01-01

    Active noise reduction is a successful addition to passive ear-defenders for improvement of the sound attenuation at low frequencies. Design and assessment methods are discussed, focused on subjective and objective attenuation measurements, stability, and high noise level applications. Active noise

  5. Digitally controlled active noise reduction with integrated speech communication

    NARCIS (Netherlands)

    Steeneken, H.J.M.; Verhave, J.A.

    2004-01-01

    Active noise reduction is a successful addition to passive ear-defenders for improvement of the sound attenuation at low frequencies. Design and assessment methods are discussed, focused on subjective and objective attenuation measurements, stability, and high noise level applications. Active noise

  6. Active vibration and noise control by hybrid active acoustic panels

    Energy Technology Data Exchange (ETDEWEB)

    Stoebener, U.; Gaul, L. [Stuttgart Univ. (Germany). Inst. A fuer Mechanik

    2001-07-01

    In the present paper a hybrid passive and active treatment for vibration and noise reduction of plate type structures is proposed. The treatment is manufactured as sandwich structure and is called hybrid active acoustic panel. The passive component is used to reduce the vibration and sound radiation for high frequencies whereas the active part of the system is designed for the low frequency range. By selecting the thickness of the passive damping layer a certain frequency limit is defined, which divides the high and low frequency range. The actuator and sensor layout of the active component is evaluated by using the mode shapes of the low frequency range. According to the evaluated layout a hybrid active acoustic panel is manufactured and experimentally tested. The experimental results validate the proposed concept. (orig.)

  7. Active vibrations and noise control for turboprop application research program activities

    Science.gov (United States)

    Paonessa, A.; Concilio, A.; Lecce, Leonardo V.

    1992-01-01

    The objectives of this work include the following: (1) development of active noise control techniques to alleviate inefficiencies and drawbacks of passive noise control approach especially at low frequencies; (2) reduction of structurally radiated noise applying external forces to the vibrating structure by means of force actuators made of piezoelectric material; and (3) reduction of fuselage vibration levels in propeller driven aircraft by means of distributed piezoelectric actuators that are actively controlled.

  8. Fundamental study of noise reduction by active noise control. Active soon seigyo ni yoru soon taisaku no kiso kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, T.; Naganawa, A. (Chubu Electric Power Co. Inc., Nagoya (Japan))

    1994-05-01

    Fundamental experiments were conducted on active noise control as sound insulation fence. This control method generates a sound source with the same amplitude and opposite phase as noise, and reduces noise through the interference of acoustic wave from the source. However, this method has too many problems with the three-dimensional sound field to be actually exploited in this environment. The following experiments were conducted to apply the active noise control to the sound insulation fence: one method of installing a geometric path along the inner side of the sound insulation fence used the acoustic delay process generated on the source side to attenuate the sound pressure level on top of the fence through interference of routing difference sound. The other method used an additional sound source attached to the bottom of the geometric path above to obtain a higher attenuation than using the simple sound insulation fence. At the second step, the active control duct model was used for the test. Then, the three-dimensional model test was conducted for active control of the sound insulation fence. The results of these fundamental experiments have indicated that each method can reduce the relative sound pressure level and the active noise control system using the acoustic phase difference can effectively reduce noise with dominant components in a low frequency band. There are still several problems with the three-dimensional mock-up model. 4 refs., 18 figs., 2 tabs.

  9. Performing Active Noise Control and Acoustic Experiments Remotely

    Directory of Open Access Journals (Sweden)

    Imran Khan

    2012-12-01

    Full Text Available This paper presents a novel and advanced remotely controlled laboratory for conducting Active Noise Control (ANC, acoustic and Digital Signal Processing (DSP experiments. The laboratory facility, recently developed by Blekinge Institute of Technology (BTH Sweden, supports remote learning through internet covering beginners level such as simple experimental measurements to advanced users and even researchers such as algorithm development and their performance evaluation on DSP. The required software development for ANC algorithms and equipment control are carried out anywhere in the world remotely from an internet-connected client PC using a standard web browser. The paper describes in detail how ANC, acoustic and DSP experiments can be performed remotely The necessary steps involved in an ANC experiment such as validity of ANC, forward path estimation and active control applied to a broad band random noise [0-200Hz] in a ventilation duct will be described in detail. The limitations and challenges such as the forward path and nonlinearities pertinent to the remote laboratory setup will be described for the guidance of the user. Based on the acoustic properties of the ventilation duct some of the possible acoustic experiments such as mode shapes analysis and standing waves analysis etc. will also be discussed in the paper.

  10. Phasor Representation for Narrowband Active Noise Control Systems

    Directory of Open Access Journals (Sweden)

    Chen Fu-Kun

    2008-01-01

    Full Text Available The phasor representation is introduced to identify the characteristic of the active noise control (ANC systems. The conventional representation, transfer function, cannot explain the fact that the performance will be degraded at some frequency for the narrowband ANC systems. This paper uses the relationship of signal phasors to illustrate geometrically the operation and the behavior of two-tap adaptive filters. In addition, the best signal basis is therefore suggested to achieve a better performance from the viewpoint of phasor synthesis. Simulation results show that the well-selected signal basis not only achieves a better convergence performance but also speeds up the convergence for narrowband ANC systems.

  11. Phasor Representation for Narrowband Active Noise Control Systems

    Directory of Open Access Journals (Sweden)

    Fu-Kun Chen

    2008-05-01

    Full Text Available The phasor representation is introduced to identify the characteristic of the active noise control (ANC systems. The conventional representation, transfer function, cannot explain the fact that the performance will be degraded at some frequency for the narrowband ANC systems. This paper uses the relationship of signal phasors to illustrate geometrically the operation and the behavior of two-tap adaptive filters. In addition, the best signal basis is therefore suggested to achieve a better performance from the viewpoint of phasor synthesis. Simulation results show that the well-selected signal basis not only achieves a better convergence performance but also speeds up the convergence for narrowband ANC systems.

  12. Active Control of Fan Noise: Feasibility Study. Volume 3; Active Fan Noise Cancellation in the NASA Lewis Active Noise Control Fan Facility

    Science.gov (United States)

    Pla, Frederic G.; Hu, Ziqiang; Sutliff, Daniel L.

    1996-01-01

    This report describes the Active Noise Cancellation (ANC) System designed by General Electric and tested in the NASA Lewis Research Center's (LERC) 48 inch Active Noise Control Fan (ANCF). The goal of this study is to assess the feasibility of using wall mounted secondary acoustic sources and sensors within the duct of a high bypass turbofan aircraft engine for global active noise cancellation of fan tones. The GE ANC system is based on a modal control approach. A known acoustic mode propagating in the fan duct is canceled using an array of flush-mounted compact sound sources. The canceling modal signal is generated by a modal controller. Inputs to the controller are signals from a shaft encoder and from a microphone array which senses the residual acoustic mode in the duct. The key results are that the (6,0) was completely eliminated at the 920 Hz design frequency and substantially reduced elsewhere. The total tone power was reduced 6.8 dB (out of a possible 9.8 dB). Farfield reductions of 15 dB (SPL) were obtained. The (4,0) and (4,1) modes were reduced simultaneously yielding a 15 dB PWL decrease. The results indicate that global attenuation of PWL at the target frequency was obtained in the aft quadrant using an ANC actuator and sensor system totally contained within the duct. The quality of the results depended on precise mode generation. High spillover into spurious modes generated by the ANC actuator array caused less than optimum levels of PWL reduction. The variation in spillover is believed to be due to calibration procedure, but must be confirmed in subsequent tests.

  13. Smart materials and active noise and vibration control in vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Doppenberg, E.J.J.; Berkhoff, A.P.; Overbeek, M. van [TNO Institute of Applied Physics, Delft (Netherlands)

    2001-07-01

    Results are presented for the reduction of sound radiated from a structure using different control methodologies. Two approaches for active structural acoustic control are mentioned to reduce sound radiated by the structure: the acoustic approach or the vibro-acoustic approach. In both cases integrated actuators in structure materials are necessary to realise feasible products. Furthermore the development of an efficient shaker for Active Isolation techniques is described. The prototype of TNO TPD can produce a force of 400 N up to 250 Hz at a good performance-volume ratio. To enhance the robustness of the active control applications, the use of the subspace identification based control methods are developed. The robustness property of subspace identification methods forms the basis of an accurate model updating mechanism, using small size data batches. The performed simulations reveal excellent robustness performance under very general noise conditions or during operation of the control system. Furthermore the development of the techniques can be exploited to realise sound comfort requirements to enhance audible communications of vehicle related applications. To anticipate to these developments in the automotive industry, TNO has set up a Sound and Vibrations Research Centre with Twente University and a research program on Smart Panels with the Delft University. To investigate the potential markets and applications for sound comfort in the means of transportation, TNO-TPD and the Institute of Sound and Vibration Research in England (ISVR) have agreed on a cooperative venture to develop and realise 'active control of electroacoustics' (ACE). (orig.)

  14. Active noise control and application; Active soon seigyo gijutsu to sono tekiyorei

    Energy Technology Data Exchange (ETDEWEB)

    Muto, M.; Hayashi, M.; Kawai, T.; Sato, F.; Kanbe, K. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan); Inoue, Y.; Takada, K.

    1995-11-01

    The recent rapid progress of electronic devices and signal processing techniques has allowed the practical application of active noise control(ANC) for reduction of noise. The principle of ANC is to cancel a noise by an anti-noise which has the same amplitude of the noise but the inverse phase. For noise reduction in gas ducts, the one dimensional ANC theory can be applied. However, there are still several technical issues particulars to individual plants to be studied and solved. This paper describes the ANC system using the hydraulically actuated speaker which has been developed at IHI, and applications to reduction of low frequency sound emitted at the exit of a stack from a large induction fan. Another application for tractor cabin is also described, indicating successful noise reduction. 6 refs., 12 figs.

  15. Method and System for Active Noise Control of Tiltrotor Aircraft

    Science.gov (United States)

    Betzina, Mark D. (Inventor); Nguyen, Khanh Q. (Inventor)

    2003-01-01

    Methods and systems for reducing noise generated by rotating blades of a tiltrotor aircraft. A rotor-blade pitch angle associated with the tiltrotor aircraft can be controlled utilizing a swashplate connected to rotating blades of the tiltrotor aircraft. One or more Higher Harmonic Control (HHC) signals can be transmitted and input to a swashplate control actuator associated with the swashplate. A particular blade pitch oscillation (e.g., four cycles per revolution) is there-after produced in a rotating frame of reference associated with the rotating blades in response to input of an HHC signal to the swashplate control actuator associated with the swashplate to thereby reduce noise associated with the rotating blades of the tiltrotor aircraft. The HHC signal can be transmitted and input to the swashplate control actuator to reduce noise of the tiltrotor aircraft in response to a user input utilizing an open-loop configuration.

  16. Study on the application of digital signal processor (DSP) to adaptive control. 2. Active noise control to noise from a duct; DSP ni yoru tekio seigyo. 2. Duct kaikotan no soon eno active noise control

    Energy Technology Data Exchange (ETDEWEB)

    Kino, N.; Kitagawa, T.; Aoki, K. [Shizuoka Industrial Research Institute of Shizuoka prefecture, Shizuoka (Japan)

    1995-09-01

    Recent developments in signal processing technology, computer and LSI technology, especially DSP technology have made it possible to process sampled and quantized sound signals in real time. So sound field processing technology and sound field control technology have been made rapid progress. Active noise control technology is one of the sound field control technologies. And it can be applied to low frequency noise reduction problems that we couldn`t cope with in usual way. So we developed an experimental device of active noise control. We report how we developed this device and refer to the experimental results about a random frequency noise in this report. 5 refs., 18 figs., 1 tab.

  17. Active structural acoustic control of helicopter interior multifrequency noise using input-output-based hybrid control

    Science.gov (United States)

    Ma, Xunjun; Lu, Yang; Wang, Fengjiao

    2017-09-01

    This paper presents the recent advances in reduction of multifrequency noise inside helicopter cabin using an active structural acoustic control system, which is based on active gearbox struts technical approach. To attenuate the multifrequency gearbox vibrations and resulting noise, a new scheme of discrete model predictive sliding mode control has been proposed based on controlled auto-regressive moving average model. Its implementation only needs input/output data, hence a broader frequency range of controlled system is modelled and the burden on the state observer design is released. Furthermore, a new iteration form of the algorithm is designed, improving the developing efficiency and run speed. To verify the algorithm's effectiveness and self-adaptability, experiments of real-time active control are performed on a newly developed helicopter model system. The helicopter model can generate gear meshing vibration/noise similar to a real helicopter with specially designed gearbox and active struts. The algorithm's control abilities are sufficiently checked by single-input single-output and multiple-input multiple-output experiments via different feedback strategies progressively: (1) control gear meshing noise through attenuating vibrations at the key points on the transmission path, (2) directly control the gear meshing noise in the cabin using the actuators. Results confirm that the active control system is practical for cancelling multifrequency helicopter interior noise, which also weakens the frequency-modulation of the tones. For many cases, the attenuations of the measured noise exceed the level of 15 dB, with maximum reduction reaching 31 dB. Also, the control process is demonstrated to be smoother and faster.

  18. 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.

  19. Active control of propeller induced noise fields inside a flexible cylinder

    Science.gov (United States)

    Lester, H. C.; Fuller, C. R.

    1986-01-01

    An active noise control model has been evaluated for reducing aircraft interior noise. The structural noise transmission properties of an aircraft fuselage were modelled as a flexible cylinder excited by external acoustic dipoles simulating the noise produced by twin propellers. The amplitudes of an internal distribution of monopole control sources were determined such that the area-weighted mean square acoustic pressure was minimized in the propeller plane. The noise control model was evaluated at low frequencies corresponding to the blade passage frequency and first few harmonics of a typical turbo-prop aircraft. Interior noise reductions of 20 25 dB were achieved, over a substantial region of the cylindrical cross-section, with just a few monopole control sources. The most favorable interior noise reductions were achieved when the active noise control model was used in combination with propeller source phasing.

  20. Study of active noise control system for a commercial HVAC unit

    Science.gov (United States)

    Devineni, Naga

    Acoustic noise is a common problem in everyday life. If the appliances that are present in the work and living areas generate noise then it's a serious problem. One such appliance is the Heating, Ventilation and Air-conditioning system (HVAC) in which blower fan and compressor units are housed together. Operation of a HVAC system creates two kinds of noise. One is the noise due to the air flow and the other is the result of the compressor. Both of them exhibit different signal properties and need different strategies to control them. There has been previous efforts in designing noise control systems that can control noise from the HVAC system. These include passive methods which use sound absorption materials to attenuate noise and active methods which cancel noise by generating anti-noise. Passive methods are effective in limiting the high frequency noise, but are inefficient in controlling low frequency noise from the compressor. Compressor noise is one of the strong low frequency components that propagate through the walls, therefore there is need for deploying active signal processing methods that consider the signal properties into consideration to cancel the noise acoustically. The quasi periodic nature of the compressor noise is exploited in noise modeling which aids in implementing an adaptive linear prediction filter in estimating the anti noise [12]. In this thesis, a multi channel architecture has been studied for a specific HVAC system in order to improve noise cancellation by creating larger quiet zone. In addition to the multi-channel architecture, a real time narrow band Active Noise Control (ANC) was employed to cancel noise under practical conditions.

  1. Development of active control technique for engine noise. Engine soon no active seigyo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, H.; Nakao, N.; Butsuen, T. (Mazda Motor Corp., Hiroshima (Japan))

    1994-03-31

    As a measure to reduce engine noise in a car, the active noise control (ANC) technique to eliminate noise by another noise of antiphase has been studied. The conventional filtered-x LMS control algorithm has been generally applied to the ANC, but a large quantity of arithmetic operation used for filtering is practically problematic. This paper proposes the new algorithm of which control effects and practicability have been improved by utilizing periodicity of engine noise and by introducing the idea of error scanning. This algorithm requires only 30-50% of the arithmetic operation of the above LMS method. Concerning the actual system structure, arrangement and the number of microphones have been examined based on the detailed measurement results of the spatial distribution of noise in a car. As a result, the suitable arrangement of only three microphones to reduce noise in the whole interior space of a car is found. Through the experiments, maximum noise reduction of 8dB (A scale) has been achieved at each seat position. 7 refs., 9 figs., 1 tab.

  2. H~ Estimation Approach to Active Noise Control: Theory, Algorithm and Real-Time Implementation

    Directory of Open Access Journals (Sweden)

    Bambang Riyanto

    2003-11-01

    Full Text Available This paper presents an H¥ estimation approach to active control of acoustic noise inside an enclosure. It is shown how H¥ filter theory and algorithm can be effectively applied to active noise control to provide important robustness property. Real-time implementation of the algorithm is performed on Digital Signal Processor. Experimental comparison to conventional FxLMS algorithm for active noise control is presented for both single channel and multichannel cases. While providing some new results, this paper also serves as a brief review on H¥ filter theory and on active noise control.

  3. Active Control of Fan Noise: Feasibility Study. Volume 4; Flyover System Noise Studies

    Science.gov (United States)

    Kraft, R. E.; Janardan, B. A.; Gliebe, P. R.; Kontos, G. C.

    1996-01-01

    An extension of a prior study has been completed to examine the potential reduction of aircraft flyover noise by the method of active noise control (ANC). It is assumed that the ANC system will be designed such that it cancels discrete tones radiating from the engine fan inlet or fan exhaust duct, at least to the extent that they no longer protrude above the surrounding broadband noise levels. Thus, without considering the engineering details of the ANC system design, tone levels am arbitrarily removed from the engine component noise spectrum and the flyover noise EPNL levels are compared with and without the presence of tones. The study was conducted for a range of engine cycles, corresponding to fan pressure ratios of 1.3, 1.45, 1.6, and 1.75. This report is an extension of an effort reported previously. The major conclusions drawn from the prior study, which was restricted to fan pressure ratios of 1.45 and 1.75, are that, for a fan pressure ratio of 1.75, ANC of tones gives about the same suppression as acoustic treatment without ANC. For a fan pressure ratio of 1.45, ANC appears to offer less effectiveness from passive treatment. In the present study, the other two fan pressure ratios are included in a more detailed examination of the benefits of the ANC suppression levels. The key results of this extended study are the following observations: (1) The maximum overall benefit obtained from suppression of BPF alone was 2.5 EPNdB at high fan speeds. The suppression benefit increases with increase in fan pressure ratio (FPR), (2) The maximum overall benefit obtained from suppression of the first three harmonics was 3 EPNdB at high speeds. Suppression benefit increases with increase in FPR, (3) At low FPR, only about 1.0 EPNdB maximum reduction was obtained. Suppression is primarily from reduction of BPF at high FPR values and from the combination of tones at low FPR, (4) The benefit from ANC is about the same as the benefit from passive treatment at fan pressure

  4. Active impulsive noise control using maximum correntropy with adaptive kernel size

    Science.gov (United States)

    Lu, Lu; Zhao, Haiquan

    2017-03-01

    The active noise control (ANC) based on the principle of superposition is an attractive method to attenuate the noise signals. However, the impulsive noise in the ANC systems will degrade the performance of the controller. In this paper, a filtered-x recursive maximum correntropy (FxRMC) algorithm is proposed based on the maximum correntropy criterion (MCC) to reduce the effect of outliers. The proposed FxRMC algorithm does not requires any priori information of the noise characteristics and outperforms the filtered-x least mean square (FxLMS) algorithm for impulsive noise. Meanwhile, in order to adjust the kernel size of FxRMC algorithm online, a recursive approach is proposed through taking into account the past estimates of error signals over a sliding window. Simulation and experimental results in the context of active impulsive noise control demonstrate that the proposed algorithms achieve much better performance than the existing algorithms in various noise environments.

  5. Simulation Study on Active Noise Control for a 4 Tesla MRI Scanner

    Science.gov (United States)

    Li, Mingfeng; Lim, Teik C.; Lee, Jing-Huei

    2008-01-01

    The purpose of this work is to study computationally the possibility of the application of a hybrid active noise control technique for MRI acoustic noise reduction. A hybrid control system combined with both feedforward and feedback loops embedded is proposed for potential application on active MRI noise reduction. A set of computational simulation studies were performed. Sets of MRI acoustic noise emissions measured at the patient's left ear location were recorded and used in the simulation study. By comparing three different control systems, namely the feedback, the feedforward and the hybrid control, our results revealed that the hybrid control system is the most effective. The hybrid control system achieved approximately a 20 dB reduction at the principal frequency component. We concluded that the proposed hybrid active control scheme could have a potential application for MRI scanner noise reduction. PMID:18060719

  6. Simulation study on active noise control for a 4-T MRI scanner.

    Science.gov (United States)

    Li, Mingfeng; Lim, Teik C; Lee, Jing-Huei

    2008-04-01

    The purpose of this work is to study computationally the possibility of the application of a hybrid active noise control technique for magnetic resonance imaging (MRI) acoustic noise reduction. A hybrid control system combined with both feedforward and feedback loops embedded is proposed for potential application on active MRI noise reduction. A set of computational simulation studies were performed. Sets of MRI acoustic noise emissions measured at the patient's left ear location were recorded and used in the simulation study. By comparing three different control systems, namely, the feedback, the feedforward and the hybrid control, our results revealed that the hybrid control system is the most effective. The hybrid control system achieved approximately a 20-dB reduction at the principal frequency component. We concluded that the proposed hybrid active control scheme could have a potential application for MRI scanner noise reduction.

  7. Sequentially Adapted Parallel Feedforward Active Noise Control of Noisy Sinusoidal Signals

    Directory of Open Access Journals (Sweden)

    Govind Kannan

    2009-01-01

    Full Text Available A large class of acoustic noise sources has an underlying periodic process that generates a periodic noise component, and thus their acoustic noise can in general be modeled as the sum of a periodic signal and a randomly fluctuating signal (usually a broadband background noise. Active control of periodic noise (i.e., for a mixture of sinusoids is more effective than that of random noise. For mixtures of sinusoids in a background broadband random noise, conventional FXLMS-based single filter method does not reach the maximum achievable Noise Attenuation Level (NALmax⁡. In this paper, an alternative approach is taken and the idea of a parallel active noise control (ANC architecture for cancelling mixtures of periodic and random signals is presented. The proposed ANC system separates the noise into periodic and random components and generates corresponding antinoises via separate noise cancelling filters, and tends to reach NALmax⁡ consistently. The derivation of NALmax⁡ is presented. Both the separation and noise cancellation are based on adaptive filtering. Experimental results verify the analytical development by showing superior performance of the proposed method, over the single-filter approach, for several cases of sinusoids in white noise.

  8. Active noise control of forced and induced draft fans in power generating plants

    Energy Technology Data Exchange (ETDEWEB)

    Eldada, M.V.

    1985-05-01

    A study was carried out into active noise reduction of forced draft fans in power generation plants. Active noise reduction involves detecting noise, inverting the phase and re-introducing the anti-phase signal into the duct to cancel the noise through destructive interference. Acoustic pressure transfer functions were meaured in-situ along a cross section of a 15 ft diameter fan inlet. A computer modal analysis program was written and used to analyze the field data. It was found that in frequencies between ca 5 Hz and 45 Hz the energy propagates mainly in the plane wave mode, while in higher frequencies the energy was carried mainly by higher order propagation modes. The project objective was to cancel noise up to a frequency of 130 Hz, but current technology restricted active cancellation to plane waves only. Three alternatives were considered: install a feed forward active noise control system to cancel noise at frequencies below 45 Hz; conduct research on active noise control of higher order propagation modes in ducts; or install a feed back active noise control system and a duct splitter in order to cancel noise between 30 and 130 Hz. It was recommended that the third option be selected as the next phase of the research project, which would comprise a 20 ft duct splitter and microphones, filters, amplifiers, loudspekers and cabinets. 6 refs., 12 figs.

  9. Active control of noise radiation from vibrating structures

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    The thesis is concerned with the active control of randomly vibrating structures by means of feedback control, with particular emphasis on reducing the sound radiation from such structures. A time domain model of the structural and radiation dynamics of an actively controlled plate has been...... optimal and robust discrete-time feedback controllers for active vibration control of multimodal structures have been compared. They have been showed to yield controllers with identical frequency response characteristics, even though they employ completely different methods of numerical solutions...... developed, based on the theory of radiation filters for estimating the sound radiation from multimodal vibrations. This model has then been used in simulations of optimal feedback control, with special emphasis of the stability margins of the optimal control scheme. Two different methods of designing...

  10. Active control of noise radiation from vibrating structures

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    The thesis is concerned with the active control of randomly vibrating structures by means of feedback control, with particular emphasis on reducing the sound radiation from such structures. A time domain model of the structural and radiation dynamics of an actively controlled plate has been...... developed, based on the theory of radiation filters for estimating the sound radiation from multimodal vibrations. This model has then been used in simulations of optimal feedback control, with special emphasis of the stability margins of the optimal control scheme. Two different methods of designing...... optimal and robust discrete-time feedback controllers for active vibration control of multimodal structures have been compared. They have been showed to yield controllers with identical frequency response characteristics, even though they employ completely different methods of numerical solutions...

  11. A new approach to control noise from entertainment facilities: Active control and measurement of amplified community noise

    Science.gov (United States)

    Peppin, Richard J.; Casamajó, Joan

    2003-04-01

    While traffic noise is perhaps the most pervasive of community noises, much of the contribution now comes from amplified sound: live music, discos, theme parks, and exercise studios. Those producing the sound or music want it loud and those not interested want to be protected against noise. Noise limits at the receiving or producing property line must be met for the minimum community acceptance. However the time-, and perhaps the spatially-, varying sound in entertainment facilities is often constantly modified (and maybe monitored) near the source of the sound. Hence it is hard to relate and to control the sound at the property line. This paper presents a unique noise control device. It is based on the octave band ``transfer function'' between the sound produced in the entertainment area and the noise received at the property line. The overall insulation can be measured and is input to the instrument. When a noise level limit is exceeded at the receiver, due to the amplified interior noise at the facility, the sound output of the device is automatically controlled to reduce the noise. The paper provides details of the design and possible abatement scenarios with examples.

  12. Robust and fast schemes in broadband active noise and vibration control

    NARCIS (Netherlands)

    Fraanje, Petrus Rufus

    2004-01-01

    This thesis presents robust and fast active control algorithms for the suppression of broadband noise and vibration disturbances. Noise disturbances, e.g., generated by engines in airplanes and cars or by air ow, can be reduced by means of passive or active methods.

  13. Robust and fast schemes in broadband active noise and vibration control

    NARCIS (Netherlands)

    Fraanje, P.R.

    2004-01-01

    This thesis presents robust and fast active control algorithms for the suppression of broadband noise and vibration disturbances. Noise disturbances, e.g., generated by engines in airplanes and cars or by air ow, can be reduced by means of passive or active methods.

  14. Adapting active noise control headsets for the mining industry: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Vipac Engineers and Scientists Ltd., North Ryde, NSW (Australia)

    1996-02-01

    Noise induced hearing loss and its consequences with regard to occupational health and safety remain a major problem in the coal industry, especially underground. Australian Standards for exposure to noise in the occupational environment are being lowered from 8-hour equivalent continuous A-weighted sound pressure level of 90 dBA to 85 dBA. The most desirable solution is to treat the noise problem at source. Where noise control strategies are not feasible, the use of hearing protection devices remains the most widely used strategy for limiting the exposure to noise in the work place. This project aimed to demonstrate design specifications for ANC (Active Noise Control) Headsets for use in the coal mining industry, especially underground. Tests showed some devices benefit from a significantly improved noise attenuation performance at low frequencies due the ANC system. Using measured noise from continuous miner and the measured noise attenuation performance of one of the ANC headsets under evaluation as an example, it was demonstrated that with Active Noise Control, the overall Leq noise level was reduced from 90 dBA (with passive hearing protection only) to 77 dBA. The final part of the project was to establish a set of specifications for the manufacturers to use in developing ANC headsets for use underground. (author). 8 tabs., 7 figs., 20 refs.

  15. Active Control of Automotive Intake Noise under Rapid Acceleration using the Co-FXLMS Algorithm

    Science.gov (United States)

    Lee, Hae-Jin; Lee, Gyeong-Tae; Oh, Jae-Eung

    The method of reducing automotive intake noise can be classified by passive and active control techniques. However, passive control has a limited effect of noise reduction at low frequency range (below 500 Hz) and is limited by the space of the engine room. However, active control can overcome these passive control limitations. The active control technique mostly uses the Least-Mean-Square (LMS) algorithm, because the LMS algorithm can easily obtain the complex transfer function in real-time, particularly when the Filtered-X LMS (FXLMS) algorithm is applied to an active noise control (ANC) system. However, the convergence performance of the LMS algorithm decreases significantly when the FXLMS algorithm is applied to the active control of intake noise under rapidly accelerating driving conditions. Therefore, in this study, the Co-FXLMS algorithm was proposed to improve the control performance of the FXLMS algorithm during rapid acceleration. The Co-FXLMS algorithm is realized by using an estimate of the cross correlation between the adaptation error and the filtered input signal to control the step size. The performance of the Co-FXLMS algorithm is presented in comparison with that of the FXLMS algorithm. Experimental results show that active noise control using Co-FXLMS is effective in reducing automotive intake noise during rapid acceleration.

  16. Smart Materials and Active Noise and Vibration Control in Vehicles

    NARCIS (Netherlands)

    Doppenberg, E.J.J.; Berkhoff, A.P.; Overbeek, van M.

    2001-01-01

    The paper presents the results for the reduction of sound radiated from a structure using different control methodologies, and discusses two approaches for active structural acoustic control: the acoustic approach or the vibro-acoustic approach. Integrated actuators in structure material are necessa

  17. Smart Materials and Active Noise and Vibration Control in Vehicles

    NARCIS (Netherlands)

    Doppenberg, E.J.J.; Berkhoff, Arthur P.; van Overbeek, M.; Gissinger, G.L.

    2001-01-01

    The paper presents the results for the reduction of sound radiated from a structure using different control methodologies, and discusses two approaches for active structural acoustic control: the acoustic approach or the vibro-acoustic approach. Integrated actuators in structure material are

  18. Integration of Bass Enhancement and Active Noise Control System in Automobile Cabin

    Directory of Open Access Journals (Sweden)

    Liang Wang

    2008-01-01

    Full Text Available With the advancement of digital signal processing technologies, consumers are more concerned with the quality of multimedia entertainment in automobiles. In order to meet this demand, an audio enhancement system is needed to improve bass reproduction and cancel engine noise in the cabins. This paper presents an integrated active noise control system that is based on frequency-sampling filters to track and extract the bass information from the audio signal, and a multifrequency active noise equalizer to tune the low-frequency engine harmonics to enhance the bass reproduction. In the noise cancellation mode, a maximum of 3 dB bass enhancement can be achieved with significant noise suppression, while higher bass enhancement can be achieved in the bass enhance mode. The results show that the proposed system is effective for solving both the bass audio reproduction and the noise control problems in automobile cabins.

  19. An efficient feedback active noise control algorithm based on reduced-order linear predictive modeling of FMRI acoustic noise.

    Science.gov (United States)

    Kannan, Govind; Milani, Ali A; Panahi, Issa M S; Briggs, Richard W

    2011-12-01

    Functional magnetic resonance imaging (fMRI) acoustic noise exhibits an almost periodic nature (quasi-periodicity) due to the repetitive nature of currents in the gradient coils. Small changes occur in the waveform in consecutive periods due to the background noise and slow drifts in the electroacoustic transfer functions that map the gradient coil waveforms to the measured acoustic waveforms. The period depends on the number of slices per second, when echo planar imaging (EPI) sequencing is used. Linear predictability of fMRI acoustic noise has a direct effect on the performance of active noise control (ANC) systems targeted to cancel the acoustic noise. It is shown that by incorporating some samples from the previous period, very high linear prediction accuracy can be reached with a very low order predictor. This has direct implications on feedback ANC systems since their performance is governed by the predictability of the acoustic noise to be cancelled. The low complexity linear prediction of fMRI acoustic noise developed in this paper is used to derive an effective and low-cost feedback ANC system.

  20. Approaches to Adaptive Active Acoustic Noise Control at a Point Using Feedforward Techniques.

    Science.gov (United States)

    Zulch, Peter A.

    Active acoustic noise control systems have been of interest since their birth in the 1930's. The principle is to superimpose on an unwanted noise wave shape its inverse with the intention of destructive interference. This work presents two approaches to this idea. The first approach uses a direct design method to develop a controller using an auto-regressive moving-average (ARMA) model that will be used to condition the primary noise to produce the required anti-noise for cancellation. The development of this approach has shown that the stability of the controller relies heavily on a non-minimum phase model of the secondary noise path. For this reason, a second approach, using a controller consisting of two parts was developed. The first part of the controller is designed to cancel broadband noise and the second part is an adaptive controller designed to cancel periodic noise. A simple technique for identifying the parameters of the broadband controller is developed. An ARMA model is used, and it is shown that its stability is improved by prefiltering the test signal with a minimum-phase inverse of the secondary noise channel. The periodic controller uses an estimate of the fundamental frequency to cancel the first few harmonics of periodic noise. A computationally efficient adaptive technique based on least squares is developed for updating the harmonic controller gains at each time step. Experimental results are included for the broadband controller, the harmonic controller, and the combination of the two algorithms. The advantages of using both techniques in conjunction are shown using test cases involving both broadband noise and periodic noise.

  1. Experimental Investigation of Active Noise Controller for Internal Combustion Engine Exhaust System

    Science.gov (United States)

    Wu, Jian-Da; Chen, Chih-Keng; Lee, Chun-Ying; Lee, Tian-Hua

    2002-10-01

    Two active noise control (ANC) algorithms for internal combustion engine exhaust systems are developed and their performances are compared in various experiments. The first controller is based on the filtered-x least mean square (FXLMS) algorithm with feedback neutralization, while the second is a fixed controller with a gain-scheduled active control technique for broadband attenuation with thermal effects. Both control algorithms are implemented on a digital signal processing (DSP) platform. Experiments are carried out to evaluate the attenuation performance of the proposed active noise control systems for an engine exhaust system. The results of the experiments indicate that both the adaptive controller and the gain-scheduled controller effectively suppress the noise of engine exhaust systems. The experimental comparison and analysis of the proposed controllers are also described.

  2. Active control of periodic fan noise in laptops: spectral width requirements in delayed buffer implementation

    Directory of Open Access Journals (Sweden)

    H. A. Cordourier‐Maruri

    2009-08-01

    Full Text Available An active control system intended for the reduction of strictly periodic noise components in computer cooling fans is described,which is based on high‐performance digital sound device architectures found in some personal computers. The systemovercomes causality and synchronization constrains imposed by delayed buffering, as usually found in computer audioprocessing. Performance of the system is demonstrated and evaluated through measurements in a physical implementation ofactive noise control of synthetic tones combined with laptop fan noise, carried out under anechoic and slightly reverberantconditions. Tests on other types of tonal noise sources, like an electrical transformer, were also carried out. However, its widerapplicability to the cancellation of tonal noise has been proved compromised by weak periodicity issues found and reported inthis work. Also, a study of noise spectral width requirements for successful operation is presented.

  3. Active noise and vibration control for vehicular applications

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, P.S.; Ellis, S.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project investigated semi-active suspension systems based on real time nonlinear control of magneto-rheological (MR) shock absorbers. This effort was motivated by Laboratory interactions with the automobile industry and with the Defense Department. Background research and a literature search on semi-active suspensions was carried out. Numerical simulations of alternative nonlinear control algorithms were developed and adapted for use with an MR shock absorber. A benchtop demonstration system was designed, including control electronics and a mechanical demonstration fixture to hold the damper/spring assembly. A custom-made MR shock was specified and procured. Measurements were carried out at Los Alamos to characterize the performance of the device.

  4. Controlled Noise Seismology

    KAUST Repository

    Hanafy, Sherif M.

    2015-08-19

    We use controlled noise seismology (CNS) to generate surface waves, where we continuously record seismic data while generating artificial noise along the profile line. To generate the CNS data we drove a vehicle around the geophone line and continuously recorded the generated noise. The recorded data set is then correlated over different time windows and the correlograms are stacked together to generate the surface waves. The virtual shot gathers reveal surface waves with moveout velocities that closely approximate those from active source shot gathers.

  5. Filtered-X Radial Basis Function Neural Networks for Active Noise Control

    Directory of Open Access Journals (Sweden)

    Bambang Riyanto

    2004-05-01

    Full Text Available This paper presents active control of acoustic noise using radial basis function (RBF networks and its digital signal processor (DSP real-time implementation. The neural control system consists of two stages: first, identification (modeling of secondary path of the active noise control using RBF networks and its learning algorithm, and secondly neural control of primary path based on neural model obtained in the first stage. A tapped delay line is introduced in front of controller neural, and another tapped delay line is inserted between controller neural networks and model neural networks. A new algorithm referred to as Filtered X-RBF is proposed to account for secondary path effects of the control system arising in active noise control. The resulting algorithm turns out to be the filtered-X version of the standard RBF learning algorithm. We address centralized and decentralized controller configurations and their DSP implementation is carried out. Effectiveness of the neural controller is demonstrated by applying the algorithm to active noise control within a 3 dimension enclosure to generate quiet zones around error microphones. Results of the real-time experiments show that 10-23 dB noise attenuation is produced with moderate transient response.

  6. Study of active noise control in ducts. Kanrokei ni okeru nodoteki soon seigyo hoho no kento

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Yoshiatsu

    1988-08-01

    On an active control to reduce noise in ducts, the theoretical and experimental studies of the energies ratio of the noise and the cancelling sound which should be produced by a speaker, were carried out. In case the cancelling sound was produced by the speaker which was set in the branch duct, the energies ratio varied with the setting position, the length and the cross section of the branch duct and the frequency of the noise. As the non-dimensional length of the branch duct was drawing near 0.5, the energies ratio became small. But when the non-dimensional length was 0, the ratio did not become smaller than 1. The experimental test confirmed that it was possible to reduce the noise by the cancelling sound which energies ratio was as small as about one hundredth of the noise. In case the noise was the pure sound, and the wave-length was over one fourth of the duct diameter, it was possible to reduce the noise more than 40 dB. And in case the wave-length was one eighth the reduction quantity was about 20 dB. Therefore, in case the noise is the pure sound or close to the pure sound, it is possible to apply the active noise control. 5 references, 23 figures.

  7. Experimental Performance Evaluation of a Multi-Reference Algorithm for Active Control of Propeller-Induced Cabin Noise

    OpenAIRE

    Johansson, Sven; Sjösten, Per; Persson, Per; Claesson, Ingvar

    2000-01-01

    A noisy environment dominated by low frequency noise can often be improved through the use of active noise control. This situation arises naturally in propeller aircraft where the propellers induce periodic low frequency noise inside the cabin. The cabin noise is typically rather high, and the passenger flight comfort could be improved considerably if this level were significantly reduced. This paper discusses the operation and robustness of a narrowband feedforward active noise control syste...

  8. A hybrid active/passive exhaust noise control system for locomotives

    Science.gov (United States)

    Remington, Paul J.; Knight, J. Scott; Hanna, Doug; Rowley, Craig

    2005-01-01

    A prototype hybrid system consisting of active and passive components for controlling far-field locomotive exhaust noise has been designed, assembled, and tested on a locomotive. The system consisted of a resistive passive silencer for controlling high-frequency broadband noise and a feedforward multiple-input, multiple-output active control system for suppressing low-frequency tonal noise. The active system used ten roof-mounted bandpass speaker enclosures with 2-12-in. speakers per enclosure as actuators, eight roof-mounted electret microphones as residual sensors, and an optical tachometer that sensed locomotive engine speed as a reference sensor. The system was installed on a passenger locomotive and tested in an operating rail yard. Details of the system are described and the near-field and far-field noise reductions are compared against the design goal. .

  9. Multichannel active control of random noise in a small reverberant room

    DEFF Research Database (Denmark)

    Laugesen, Søren; Elliott, Stephen J.

    1993-01-01

    An algorithm for multichannel adaptive IIR (infinite impulse response) filtering is presented and applied to the active control of broadband random noise in a small reverberant room. Assuming complete knowledge of the primary noise, the theoretically optimal reductions of acoustic energy...... multichannel FIR (finite impulse response) and IIR filters are then compared for a four-secondary-source, eight-error microphone active control system, and it is found that for the present application FIR filters are sufficient when the primary noise source is a loudspeaker. Some experiments are then presented...... with the primary noise field generated by a panel excited by a loudspeaker in an adjoining room. These results show that far better performances are provided by IIR and FIR filters when the primary source has a lightly damped dynamic behavior which the active controller must model...

  10. Evaluating the performance of active noise control systems in commercial and industrial applications

    Energy Technology Data Exchange (ETDEWEB)

    Depies, C.; Deneen, S.; Lowe, M.; Wise, S.

    1995-06-01

    Active sound cancellation technology is increasingly being used to quiet commercial and industrial air-moving devices. Engineers and designers are implementing active or combination active/passive technology to control sound quality in the workplace and the acoustical environment in residential areas near industrial facilities. Sound level measurements made before and after the installation of active systems have proved that significant improvements in sound quality can be obtained even if there is little or no change in the NC/RC or dBA numbers. Noise produced by centrifugal and vane-axial fans, pumps and blowers, commonly used for ventilation and material movement in industry, are frequently dominated by high amplitude, tonal noise at low frequencies. And the low-frequency noise produced by commercial air handlers often has less tonal and more broadband characteristics, resulting in audible duct rumble noise and objectionable room spectrums. Because the A-weighting network, which is commonly used for industrial noise measurements, de-emphasizes low frequencies, its single number rating can be misleading in terms of judging the overall subjective sound quality in impacted areas and assessing the effectiveness of noise control measures. Similarly, NC values, traditionally used for commercial HVAC acoustical design criteria, can be governed by noise at any frequency and cannot accurately depict human judgment of the aural comfort level. Analyses of frequency spectrum characteristics provide the most effective means of assessing sound quality and determining mitigative measures for achieving suitable background sound levels.

  11. Improving the Effectiveness of Communication Headsets with Active Noise Reduction: Influence of Control Structure

    Science.gov (United States)

    2005-04-01

    for two circumaural communication headsets with similar passive, and active, noise reductions, one with an analog feedback control system and the...the feedback control system to maintain stability of the feedback loop, as well as the presence of communication sounds sensed by the control

  12. Analytical and experimental results for active noise control within cylindrical cavities bounded by elastic adaptive structures

    Energy Technology Data Exchange (ETDEWEB)

    Baier, H.; Dool, T. van den; Haeusler, S.; Faust, M. [Technische Univ. Muenchen (Germany)]|[TNO, Delf (Netherlands)]|[Dornier, Friedrichshafen (Germany)

    1998-10-01

    The feasibility of differnt concepts for active noise control in elastically bounded cylindrical cavities such as in launcher fairings is investigated. Analytical and experimental studies are carried out for feedforward and feedback controllers and different types of actuators and sensors. The feasibility and potential of the approach is demonstrated, but further progress on controller speed and actuator capability has to be made. (orig.)

  13. Development of an active noise control system with minimized amount of calculation; Shoenzan ryogata active soon seigyo system no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, M. [Hitachi, Ltd., Tokyo (Japan); Sasaki, M.; Hori, Y. [Gifu University, Gifu (Japan); Fujisawa, F. [Hachinohe Institute of Technology, Aomori (Japan); Sumida, I. [Chubu University, Nagoya (Japan)

    1997-12-20

    This paper proposes an active noise control system with minimized amount of calculation for periodic noise. A modified algorithm based on the filtered-x adaptive notch filter is applied on the diesel engine noise generate d in the cabin of an all-terrain vehicle. Diesel engine noise is periodic and includes some harmonic components due to engine rotation. Numerical simulation results using measured data indicated that the proposed system could be controlled by using fewer calculations compared to the conventional system. The controller was made using an eight bit microcomputer without a digital signal processor and installed in the vehicle. Results of the driving tests achieved a large noise reduction for some harmonic components, second, fourth and sixth order components. This shows that the control system is effective for noise reduction. 5 refs., 8 figs., 6 tabs.

  14. Extra-low-noise refrigerator with active noise control system, GR-W40NVI. Nodo seigyo choseiongata reizoko GR-W40NVI

    Energy Technology Data Exchange (ETDEWEB)

    Sekiguchi, Y.; Nakanishi, K.; Saruta, S. (Toshiba Corp., Tokyo (Japan))

    1991-04-20

    Aiming at lowering the noise down to a domestic background noise level, development was made of GR-W40NVI, extra-low-noise refrigerator with an active noise control system. The active control for lowering the noise is methodically to artificially generate sound, reverse in phase against the noise to be generated, silence it by acoustic wave interference, and theoretically reduce the acoustic pressure to zero. Such a technology was applied to the refrigerator morphologically as follows: In order to silence the noise, generated by the compressor and three-dimensionally diffused, by a simple structure, duct structure is applied for the noise to be diffused in one direction only, by acoustically insulating and confining the compressor with exception of its thermal exhaust opening. In order to lower the noise, generated by the compressor and amplified in zonal region, the active control is applied against the low frequency noise, while the conventional acoustic insulation/absorption technology is done against the high frequency noise. In order to quickly and accurately prepare sound, reverse in phase against the noise under fluctuation, signal processing is made by using digital signal processor (DSP), hardware exclusively for it. As a result, the noise was lowered by about 7dB (1/5) for the basic type of refrigerator. 12 figs.

  15. Secondary Path Modeling Method for Active Noise Control of Power Transformer

    Science.gov (United States)

    Zhao, Tong; Liang, Jiabi; Liang, Yuanbin; Wang, Lixin; Pei, Xiugao; Li, Peng

    The accuracy of the secondary path modeling is critical to the stability of active noise control system. On condition of knowing the input and output of the secondary path, system identification theory can be used to identify the path. Based on the experiment data, correlation analysis is adopted to eliminate the random noise and nonlinear harmonic in the output data in order to obtain the accurate frequency characteristic of the secondary path. After that, Levy's Method is applied to identify the transfer function of the path. Computer simulation results are given respectively, both showing the proposed off-line modeling method is feasible and applicable. At last, Levy's Method is used to attain an accurate secondary path model in the active control of transformer noise experiment and achieves to make the noise sound level decrease about 10dB.

  16. A Computational Study of BVI Noise Reduction Using Active Twist Control

    Science.gov (United States)

    Fogarty, David E.; Wilbur, Matthew L.; Sekula, Martin K.

    2010-01-01

    The results of a computational study examining the effects of active-twist control on blade-vortex interaction (BVI) noise using the Apache Active Twist Rotor are presented. The primary goal of this activity is to reduce BVI noise during a low-speed descent flight condition using active-twist control. Rotor aeroelastic behavior was modeled using the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics code and the rotor noise was predicted using the acoustics code PSU-WOPWOP. The accuracy of the analysis was validated through comparisons with experimental acoustic data for the first generation Active Twist Rotor at an advance ratio of mu=0.14. The application of active-twist to the main rotor blade system consisted of harmonic actuation frequencies ranging from 2P to 5P, control phase angles from 0' to 360 , and tip-twist amplitudes ranging from 0.5 to 4.0 . The acoustic analysis was conducted for a single low-speed flight condition of advance ratio =0.14 and shaft angle-of-attack, c^=+6 , with BVI noise levels predicted on a flat plane of observers located 1.1 rotor diameters beneath the rotor. The results indicated reductions of up to 11dB in BVI noise using 1.25 tip-twist amplitude with negligible effects on 4P vertical hub shear.

  17. Active structural acoustic control of noise from power transformers; Aktive Laermdaemmung von Leistungstransformatoren mit Gegenlaerm

    Energy Technology Data Exchange (ETDEWEB)

    Brungardt, K.; Vierengel, J.; Weissmann, K. [Quiet Power Systems Inc., New York, NY (United States); Schemel, G.; Lorin, P. [ABB Secheron SA, Genf (Switzerland)

    1998-04-06

    Population growth and tougher zoning regulations mean transformer noise is a growing problem for electric utilities. Transformer noise is dominanted by low frequency tones which are difficult to control by passive means, but are effectively attenuated by active noise control. This paper details a novel noise control system that actively attenuates transformer noise using a combination of structural actuators mounted on the radiating surface of the transformer tank, and specially designed resonant acoustic devices located just off the tank surface. An adaptive selfcalibrating, multi-channel controller is used to automatically respond to changes in noise level during transformer operation. Performance results have been proven at a number of field installations in utility substations, and an installation case study is provided here as an example. (orig.) [Deutsch] Beim Betrieb von Leistungstransformatoren entstehen Geraeusche, die besonders in der Naehe von Wohngebieten als stoerend empfunden werden. Zunehmend strengere Laermschutzverordnungen erfordern daher Massnahmen um die Geraeuschentwicklung von Transformatoren zu reduzieren. Die passive Daempfung dieses `Brummens` durch Bauten ist oft mit hohen Kosten verbunden und bereitet Schwierigkeiten bei der Umsetzung. Fuer Abhilfe sorgt ein neuartiges System, das den Transformatorenlaerm aktiv daempft. Dabei setzt man zur Reduktion des Transformatorenlaerms neuartige, durch adaptive Algorythmen gesteuerte Aktuatoren ein, die den stoerenden Laerm direkt am Transformator selbst daempfen. (orig.)

  18. A rapid prototyping system for broadband multichannel active noise and vibration control

    NARCIS (Netherlands)

    Wesselink, Johan Marius

    2009-01-01

    The development system presented in this thesis consists of a highly integrated controller which can be used for different active noise and vibration control (ANVC) applications. The system consists of an embedded PC and an interfacing card that can offer up to 16 analog input and output channels. T

  19. Active control of internal cabin noise in cars. Aktive Innengeraeuschreduzierung bei Kraftfahrzeugen

    Energy Technology Data Exchange (ETDEWEB)

    Felske, A.; Gawron, H.J.; Schaaf, K.

    1990-01-01

    It is an important research task to develop methods for active noise control. In addition to reviewing possible operational areas, we discuss the efficiency based on measurements of a broadband active head-set and present an experimental two-channel system for active noise control which was tested in a VW Passat with 4 cylinder engine. Having solved the problem of decoupling in multi-channel systems, a reduction of the interior noise level for 2nd order frequencies up to 20 dB could be achieved. Standard speaker systems were used. Diagrams of sound pressure levels show the efficiency of the active compensation as a function of motor speed for the co-driver's right ear, and as a function of location both in longitudinal and transversal direction within the car cabin at a fixed motor speed. (orig./HW).

  20. Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

    Science.gov (United States)

    Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

    1996-01-01

    An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

  1. Combined MIMO adaptive and decentralized controllers for broadband active noise and vibration control

    NARCIS (Netherlands)

    Berkhoff, A.P.; Wesselink, J.M.

    2009-01-01

    Recent implementations of multiple-input multiple-output adaptive controllers for reduction of broadband noise and vibrations provide considerably improved performance over traditional adaptive algorithms. The most significant performance improvements are in terms of speed of convergence, the amount

  2. Combined MIMO adaptive and decentralized controllers for broadband active noise and vibration control

    NARCIS (Netherlands)

    Berkhoff, Arthur P.; Wesselink, J.M.

    2009-01-01

    Recent implementations of multiple-input multiple-output adaptive controllers for reduction of broadband noise and vibrations provide considerably improved performance over traditional adaptive algorithms. The most significant performance improvements are in terms of speed of convergence, the amount

  3. Noise-driven activation in human intermittent control: a double-well potential model

    CERN Document Server

    Zgonnikov, Arkady

    2014-01-01

    In controlling unstable systems humans switch intermittently between the passive and active behavior instead of controlling the system in a continuous manner. The notion of noise-driven control activation provides a richer alternative to the conventional threshold-based models of intermittent motor control. The present study represents the control activation as a random walk in a continuously changing double-well potential. The match between the proposed model and the previous data on human balancing of virtual stick prompts that the double-well approach can aid in explaining complex dynamics of human behavior in control processes.

  4. Anticipated Effectiveness of Active Noise Control in Propeller Aircraft Interiors as Determined by Sound Quality Tests

    Science.gov (United States)

    Powell, Clemans A.; Sullivan, Brenda M.

    2004-01-01

    Two experiments were conducted, using sound quality engineering practices, to determine the subjective effectiveness of hypothetical active noise control systems in a range of propeller aircraft. The two tests differed by the type of judgments made by the subjects: pair comparisons in the first test and numerical category scaling in the second. Although the results of the two tests were in general agreement that the hypothetical active control measures improved the interior noise environments, the pair comparison method appears to be more sensitive to subtle changes in the characteristics of the sounds which are related to passenger preference.

  5. Toward Active Control of Noise from Hot Supersonic Jets

    Science.gov (United States)

    2013-12-31

    control valves upstream of the nozzle through the use of a proportional-integral-derivative controller ( PID ) that allows to minimize the error by...adjusting the percentage of aperture of the tuning valve. The variability of the NPR over all the tests was found to be less "Jian 1%; Figure Ha shows the...36.7 : we first open the main valve to a value of 10%, and when ;he NPR gets high enough we open manually to 35% the tuning valve, and at t = 20s we

  6. Experiments on reduction of propeller induced interior noise by active control of cylinder vibration

    Science.gov (United States)

    Fuller, C. R.; Jones, J. D.

    1987-01-01

    The feasibility of reducing interior noise caused by advanced turbo propellers by controlling the vibration of aircraft fuselages was investigated by performing experiments in an anechoic chamber with an aircraft model test rig and apparatus. It was found that active vibration control provides reasonable global attenuation of interior noise levels for the cases of resonant (at 576 Hz) and forced (at 708 Hz) system response. The controlling mechanism behind the effect is structural-acoustic coupling between the shell and the contained field, termed interface modal filtering.

  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. Combined MIMO adaptive and decentralized controllers for broadband active noise and vibration control

    NARCIS (Netherlands)

    Berkhoff, A.P.; Wesselink, J.M.

    2011-01-01

    Model errors in multiple-input multiple-output adaptive controllers for reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. In this paper, a combination of high-authority control (HAC) and low-authority control (LAC) is considered for improved perform

  9. A Modified Structure for Feed Forward Active Noise Control Systems With Improved Performa

    Directory of Open Access Journals (Sweden)

    P.Babu

    2010-09-01

    Full Text Available Several approaches have been introduced in literature for active noise control (ANC systems. SinceFxLMS algorithm appears to be the best choice as a controller filter, researchers tend to improveperformance of ANC systems by enhancing and modifying this algorithm. In this paper, the existingFxLMS algorithm is modified which provides a new structure for improving the noise reduction andconvergence rate. Here the proposed method uses two variable step sizes, one for control filter andanother for modelling filter. The control filter step size is varied based on the secondary path thresholdsignal l dˆ . The modelling filter step size is varied based on error signal f (n . It is shown that in theproposed method ANC system noise reduction rate and convergence rate are improved dynamically thanthe FxLMS variable step size methods. The computer simulations results indicate effectiveness of theproposed method.

  10. Analysis and Optimal Condition of the Rear-Sound-Aided Control Source in Active Noise Control

    Directory of Open Access Journals (Sweden)

    Karel Kreuter

    2011-01-01

    Full Text Available An active noise control scenario of simple ducts is considered. The previously suggested technique of using an single loudspeaker and its rear sound to cancel the upstream sound is further examined and compared to the bidirectional solution in order to give theoretical proof of its advantage. Firstly, a model with a new approach for taking damping effects into account is derived based on the electrical transmission line theory. By comparison with the old model, the new approach is validated, and occurring differences are discussed. Moreover, a numerical application with the consideration of damping is implemented for confirmation. The influence of the rear sound strength on the feedback-path system is investigated, and the optimal condition is determined. Finally, it is proven that the proposed source has an advantage of an extended phase lag and a time delay in the feedback-path system by both frequency-response analysis and numerical calculation of the time response.

  11. Fast affine projections and the regularized modified filtered-error algorithm in multichannel active noise control

    NARCIS (Netherlands)

    Wesselink, J.M.; Berkhoff, A.P.

    2008-01-01

    In this paper, real-time results are given for broadband multichannel active noise control using the regularized modified filtered-error algorithm. As compared to the standard filtered-error algorithm, the improved convergence rate and stability of the algorithm are obtained by using an inner-outer

  12. A numerically stable, finite memory, fast array recursive least squares algorithm for broadband active noise control

    NARCIS (Netherlands)

    van Ophem, S.; Berkhoff, Arthur P.

    2016-01-01

    For broadband active noise control applications with a rapidly changing primary path, it is desirable to find algorithms with a rapid convergence, a fast tracking performance, and a low computational cost. Recently, a promising algorithm has been presented, called the fast-array Kalman filter, which

  13. Active control of multi-modal propagation of tonal noise in

    DEFF Research Database (Denmark)

    Laugesen, Søren

    1996-01-01

    The active control of tonal noise propagating in ducts at frequencies where many modes are able to propagate is considered. The final objective of the work reported is to cancel the prominent 450-500 Hz blade passing frequency of the rotary suction fans found in chimney stacks of power stations. ...

  14. Tracking and convergence of multi-channel kalman filters for active noise control

    NARCIS (Netherlands)

    Berkhoff, A.; Ophem, S. van

    2013-01-01

    The feed-forward broadband active noise control problem can be formulated as a state estimation problem to achieve a faster rate of convergence than the filtered reference least mean squares algorithm and possibly also a better tracking performance. A multiple input/multiple output Kalman algorithm

  15. Tracking and convergence of multi-channel Kalman filters for active noise control

    NARCIS (Netherlands)

    Berkhoff, A.P.; Ophem, S. van

    2013-01-01

    The feed-forward broadband active noise control problem can be formulated as a state estimation problem to achieve a faster rate of convergence than the filtered reference least mean squares algorithm and possibly also a better tracking performance. A multiple input/multiple output Kalman algorithm

  16. Active control of multi-modal propagation of tonal noise in

    DEFF Research Database (Denmark)

    Laugesen, Søren

    1996-01-01

    The active control of tonal noise propagating in ducts at frequencies where many modes are able to propagate is considered. The final objective of the work reported is to cancel the prominent 450-500 Hz blade passing frequency of the rotary suction fans found in chimney stacks of power stations. ...

  17. Method and system to perform energy-extraction based active noise control

    Science.gov (United States)

    Kelkar, Atul (Inventor); Joshi, Suresh M. (Inventor)

    2009-01-01

    A method to provide active noise control to reduce noise and vibration in reverberant acoustic enclosures such as aircraft, vehicles, appliances, instruments, industrial equipment and the like is presented. A continuous-time multi-input multi-output (MIMO) state space mathematical model of the plant is obtained via analytical modeling and system identification. Compensation is designed to render the mathematical model passive in the sense of mathematical system theory. The compensated system is checked to ensure robustness of the passive property of the plant. The check ensures that the passivity is preserved if the mathematical model parameters are perturbed from nominal values. A passivity-based controller is designed and verified using numerical simulations and then tested. The controller is designed so that the resulting closed-loop response shows the desired noise reduction.

  18. Active control of vibrations and noise by electrorheological fluids and piezoelectric materials

    Science.gov (United States)

    Amorosi, Joseph J.

    The combination of electrorheological (ER) fluids and piezoelectric actuators into one actively controlled intelligent sandwich plate structure for either noise or vibration control is investigated in this study. The simply supported sandwich plate consists of a core of four cavities filled with ER fluid, two elastic outer face plates, bottom plate cross stiffeners and symmetrically bonded surface piezoceramic (PZT) actuator patches. Analytical and computational simulations are performed to obtain the resultant structural response to random inputs, noise transmission into a rectangular enclosure, and sound radiation into a semi-infinite acoustic half space. An equivalent, homogeneous plate model is used in the modal decomposition of the derived governing equations of motion. This equivalency is obtained by taking the modal frequencies and mode shapes, calculated by the finite element method, to be that of the sandwich plate. The effect of actively controlling the ER fluid's stiffness material properties is incorporated into the modal frequencies and mode shapes by altering the sandwich plate's core shear and elastic moduli whereas ER fluid controllable damping is directly incorporated into the governing equations of motion as equivalent modal damping. The effect of the PZT actuators is incorporated into the governing equations of motion through direct velocity feedback utilizing collocated control. A two part control strategy is developed. First, the appropriate ER fluid voltage potential and then the PZT actuator gains are selected. Numerical results obtained in this study indicate that using ER and PZT active control up to 50 dB of noise reduction is possible at certain frequency ranges. In addition, about 15 dB reduction of the overall radiated sound pressure level can be obtained. However, for the available ER and PZT materials, the reduction of overall sound pressure to random input is shown to be on the order of 5 to 8 decibels. To improve on noise

  19. Optimal and Adaptive Virtual Unidirectional Sound Source in Active Noise Control

    Directory of Open Access Journals (Sweden)

    Dariusz Bismor

    2008-01-01

    Full Text Available One of the problems concerned with active noise control is the existence of acoustical feedback between the control value (“active” loudspeaker output and the reference signal. Various experiments show that such feedback can seriously decrease effects of attenuation or even make the whole ANC system unstable. This paper presents a detailed analysis of one of possible approaches allowing to deal with acoustical feedback, namely, virtual unidirectional sound source. With this method, two loudspeakers are used together with control algorithm assuring that the combined behaviour of the pair makes virtual propagation of sound only in one direction. Two different designs are presented for the application of active noise control in an acoustic duct: analytical (leading to fixed controller and adaptive. The algorithm effectiveness in simulations and real experiments for both solutions is showed, discussed, and compared.

  20. Robust active noise control in the loadmaster area of a military transport aircraft.

    Science.gov (United States)

    Kochan, Kay; Sachau, Delf; Breitbach, Harald

    2011-05-01

    The active noise control (ANC) method is based on the superposition of a disturbance noise field with a second anti-noise field using loudspeakers and error microphones. This method can be used to reduce the noise level inside the cabin of a propeller aircraft. However, during the design process of the ANC system, extensive measurements of transfer functions are necessary to optimize the loudspeaker and microphone positions. Sometimes, the transducer positions have to be tailored according to the optimization results to achieve a sufficient noise reduction. The purpose of this paper is to introduce a controller design method for such narrow band ANC systems. The method can be seen as an extension of common transducer placement optimization procedures. In the presented method, individual weighting parameters for the loudspeakers and microphones are used. With this procedure, the tailoring of the transducer positions is replaced by adjustment of controller parameters. Moreover, the ANC system will be robust because of the fact that the uncertainties are considered during the optimization of the controller parameters. The paper describes the necessary theoretic background for the method and demonstrates the efficiency in an acoustical mock-up of a military transport aircraft.

  1. Numerical Comparison of Active Acoustic and Structural Noise Control in a Stiffened Double Wall Cylinder

    Science.gov (United States)

    Grosveld, Ferdinand W.

    1996-01-01

    The active acoustic and structural noise control characteristics of a double wall cylinder with and without ring stiffeners were numerically evaluated. An exterior monopole was assumed to acoustically excite the outside of the double wall cylinder at an acoustic cavity resonance frequency. Structural modal vibration properties of the inner and outer shells were analyzed by post-processing the results from a finite element analysis. A boundary element approach was used to calculate the acoustic cavity response and the coupled structural-acoustic interaction. In the frequency region of interest, below 500 Hz, all structural resonant modes were found to be acoustically slow and the nonresonant modal response to be dominant. Active sound transmission control was achieved by control forces applied to the inner or outer shell, or acoustic control monopoles placed just outside the inner or outer shell. A least mean square technique was used to minimize the interior sound pressures at the nodes of a data recovery mesh. Results showed that single acoustic control monopoles placed just outside the inner or outer shells resulted in better sound transmission control than six distributed point forces applied to either one of the shells. Adding stiffeners to the double wall structure constrained the modal vibrations of the shells, making the double wall stiffer with associated higher modal frequencies. Active noise control obtained for the stiffened double wall configurations was less than for the unstiffened cylinder. In all cases, the acoustic control monopoles controlled the sound transmission into the interior better than the structural control forces.

  2. Active Control of Fan Noise: Feasibility Study. Volume 6; Theoretical Analysis for Coupling of Active Noise Control Actuator Ring Sources to an Annular Duct with Flow

    Science.gov (United States)

    Kraft, R. E.

    1996-01-01

    The objective of this effort is to develop an analytical model for the coupling of active noise control (ANC) piston-type actuators that are mounted flush to the inner and outer walls of an annular duct to the modes in the duct generated by the actuator motion. The analysis will be used to couple the ANC actuators to the modal analysis propagation computer program for the annular duct, to predict the effects of active suppression of fan-generated engine noise sources. This combined program will then be available to assist in the design or evaluation of ANC systems in fan engine annular exhaust ducts. An analysis has been developed to predict the modes generated in an annular duct due to the coupling of flush-mounted ring actuators on the inner and outer walls of the duct. The analysis has been combined with a previous analysis for the coupling of modes to a cylindrical duct in a FORTRAN computer program to perform the computations. The method includes the effects of uniform mean flow in the duct. The program can be used for design or evaluation purposes for active noise control hardware for turbofan engines. Predictions for some sample cases modeled after the geometry of the NASA Lewis ANC Fan indicate very efficient coupling in both the inlet and exhaust ducts for the m = 6 spinning mode at frequencies where only a single radial mode is cut-on. Radial mode content in higher order cut-off modes at the source plane and the required actuator displacement amplitude to achieve 110 dB SPL levels in the desired mode were predicted. Equivalent cases with and without flow were examined for the cylindrical and annular geometry, and little difference was found for a duct flow Mach number of 0.1. The actuator ring coupling program will be adapted as a subroutine to the cylindrical duct modal analysis and the exhaust duct modal analysis. This will allow the fan source to be defined in terms of characteristic modes at the fan source plane and predict the propagation to the

  3. In Situ Active Control of Noise in a 4-Tesla MRI Scanner

    Science.gov (United States)

    Li, Mingfeng; Rudd, Brent; Lim, Teik C.; Lee, Jing-Huei

    2011-01-01

    Purpose To evaluate the effectiveness of the proposed active noise control (ANC) system for the reduction of the acoustic noise emission generated by a 4 T MRI scanner during operation and to assess the feasibility of developing an ANC device that can be deployed in situ. Materials and Methods Three typical scanning sequences, namely EPI (echo planar imaging), GEMS (gradient echo multi-slice) and MDEFT (Modified Driven Equilibrium Fourier Transform), were used for evaluating the performance of the ANC system, which was composed of a magnetic compatible headset and a multiple reference feedforward filtered-x least mean square controller. Results The greatest reduction, about 55 dB, was achieved at the harmonic at a frequency of 1.3 kHz in the GEMS case. Approximately 21 dB and 30 dBA overall reduction was achieved for GEMS noise across the entire audible frequency range. For the MDEFT sequence, the control system achieved 14 dB and 14 dBA overall reduction in the audible frequency range, while 13 dB and 14 dBA reduction was obtained for the EPI case. Conclusion The result is highly encouraging because it shows great potential for treating MRI noise with an ANC application during real time scanning. PMID:21751284

  4. On the stability of adaptation process in active noise control systems.

    Science.gov (United States)

    Ardekani, Iman Tabatabaei; Abdulla, Waleed H

    2011-01-01

    The stability analysis of the adaptation process, performed by the filtered-x least mean square algorithm on weights of active noise controllers, has not been fully investigated. The main contribution of this paper is conducting a theoretical stability analysis for this process without utilizing commonly used simplifying assumptions regarding the secondary electro-acoustic channel. The core of this analysis is based on the root locus theory. The general rules for constructing the root locus plot of the adaptation process are derived by obtaining root locus parameters, including start points, end points, asymptote lines, and breakaway points. The conducted analysis leads to the derivation of a general upper-bound for the adaptation step-size beyond which the mean weight vector of the active noise controller becomes unstable. Also, this analysis yields the optimum step-size for which the adaptive active noise controller has its fastest dynamic performance. The proposed upper-bound and optimum values apply to general secondary electro-acoustic channels, unlike the commonly used ones which apply to only pure delay channels. The results are found to agree very well with those obtained from numerical analyses and computer simulation experiments.

  5. Active control of time-varying broadband noise and vibrations using a sliding-window Kalman filter

    NARCIS (Netherlands)

    van Ophem, S.; Berkhoff, Arthur P.; Sas, P; Moens, D.; Denayer, H.

    2014-01-01

    Recently, a multiple-input/multiple-output Kalman filter technique was presented to control time-varying broadband noise and vibrations. By describing the feed-forward broadband active noise control problem in terms of a state estimation problem it was possible to achieve a faster rate of

  6. Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization

    Science.gov (United States)

    Mendoza, J.; Chevva, K.; Sun, F.; Blanc, A.; Kim, S. B.

    2014-01-01

    This report describes work performed by United Technologies Research Center (UTRC) for NASA Langley Research Center (LaRC) under Contract NNL11AA06C. The objective of this program is to develop technology to reduce helicopter interior noise resulting from multiple gear meshing frequencies. A novel active vibration control approach called Minimum Actuation Power (MAP) is developed. MAP is an optimal control strategy that minimizes the total input power into a structure by monitoring and varying the input power of controlling sources. MAP control was implemented without explicit knowledge of the phasing and magnitude of the excitation sources by driving the real part of the input power from the controlling sources to zero. It is shown that this occurs when the total mechanical input power from the excitation and controlling sources is a minimum. MAP theory is developed for multiple excitation sources with arbitrary relative phasing for single or multiple discrete frequencies and controlled by a single or multiple controlling sources. Simulations and experimental results demonstrate the feasibility of MAP for structural vibration reduction of a realistic rotorcraft interior structure. MAP control resulted in significant average global vibration reduction of a single frequency and multiple frequency excitations with one controlling actuator. Simulations also demonstrate the potential effectiveness of the observed vibration reductions on interior radiated noise.

  7. A rapid prototyping system for broadband multichannel active noise and vibration control

    NARCIS (Netherlands)

    Wesselink, J.M.

    2009-01-01

    In recent years the need for active and passive noise reduction methods has increased. This is due to an increase in the ambient noise caused by industrialization and the extended use of power tools. The effects of noise on a person can be quite severe and can cause illness and in severe cased lead

  8. Numerical investigation of sound transmission through double wall cylinders with respect to active noise control

    Science.gov (United States)

    Coats, T. J.; Silcox, R. J.; Lester, H. C.

    Market pressure for more fuel efficient air travel has led to increased use of turboprop and higher bypass turbofan engines. The low frequency components of propeller, jet and boundary layer noise are difficult to attenuate with conventional passive techniques. Weight and geometric restrictions for sound absorbing meterials limit the amount and type of treatment that may be applied. An active noise control (ANC) method is providing to be an attractive alternative. The approach taken in this paper uses a numerical finite/boundary element method (FEM/BEM) that may be easilty adapted to arbitrary geometries. A double walled cylinder is modeled using commercially available software. The outer shell is modeled as an aluminum cylinder, similar to that of aircraft skins. The inner shell is modeled as a composite material representative of a lightweight, stiff trim panel. Two different inner shell materials are used. The first is representative of current trim structure, the second a much stiffer composite. The primary source is generated by an exterior acoustic monopole. Control fields are generated using normal force inputs to the inner cylindrical shell. A linear least mean square (LMS) algorithm is used to determine amplitudes of control forces that minimize the interior acoustic field. Coupling of acoustic and structural modes and noise reductions are discussed for each of the inner shell materials.

  9. Structural sensing of interior sound for active control of noise in structural-acoustic cavities.

    Science.gov (United States)

    Bagha, Ashok K; Modak, S V

    2015-07-01

    This paper proposes a method for structural sensing of acoustic potential energy for active control of noise in a structural-acoustic cavity. The sensing strategy aims at global control and works with a fewer number of sensors. It is based on the established concept of radiation modes and hence does not add too many states to the order of the system. Acoustic potential energy is sensed using a combination of a Kalman filter and a frequency weighting filter with the structural response measurements as the inputs. The use of Kalman filter also makes the system robust against measurement noise. The formulation of the strategy is presented using finite element models of the system including that of sensors and actuators so that it can be easily applied to practical systems. The sensing strategy is numerically evaluated in the framework of Linear Quadratic Gaussian based feedback control of interior noise in a rectangular box cavity with a flexible plate with single and multiple pairs of piezoelectric sensor-actuator patches when broadband disturbances act on the plate. The performance is compared with an "acoustic filter" that models the complete transfer function from the structure to the acoustic domain. The sensing performance is also compared with a direct estimation strategy.

  10. Novel Algorithm for Active Noise Control Systems Based on Frequency Selective Filters

    Institute of Scientific and Technical Information of China (English)

    Hong-liang ZHAO

    2010-01-01

    A novel algorithm for active noise control systems based on frequency selective filters (FSFANC)is presented in the paper.The FSFANC aims at the m lti-tonal noise attenuation problem.One FSFANC system copes with one of the tonal components,and several FSFANC systems can nun independently in parallel to cancel the selected multiple tones.The proposed algorithm adopts a simple structrue with only two coefficients that can be explained as the real and imaginary parts of the structure to modelthesecondary path,and estimates the secondary path by injecting sinusoidal identification signals.Theoretical analysis and laboratory experiments show that the proposed algorithm possesses some advantages,such as simpler stricture,less computational burden,greater stability,and fast canverging speed.

  11. Active noise control with fast array recursive least squares filters using a parallel implementation for numerical stability

    NARCIS (Netherlands)

    Berkhoff, A.P.; Ophem, S. van

    2015-01-01

    Noise reduction in feedforward active noise control systems with a rapidly changing primary path requires rapid convergence and fast tracking. This can be accomplished with a fast-array Kalman method which uses an efficient rotation matrix technique to calculate the filter parameters. However, finit

  12. Active noise control with fast array recursive least squares filters using a parallel implementation for numerical stability

    NARCIS (Netherlands)

    Berkhoff, Arthur P.; van Ophem, S.; Glorieux, C.

    2015-01-01

    Significant noise reduction in feedforward active noise control systems with a rapidly changing primary path requires rapid convergence and fast tracking performance. This can be accomplished with a fast-array Kalman method which uses an efficient rotation matrix technique to calculate the filter

  13. Active noise control with fast array recursive least squares filters using a parallel implementation for numerical stability

    NARCIS (Netherlands)

    Berkhoff, A.P.; Ophem, S. van

    2015-01-01

    Noise reduction in feedforward active noise control systems with a rapidly changing primary path requires rapid convergence and fast tracking. This can be accomplished with a fast-array Kalman method which uses an efficient rotation matrix technique to calculate the filter parameters. However,

  14. Design of active noise and vibration control for car oil pans using numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ringwelski, S; Luft, T.; Gabbert, U. [Otto-von-Guericke Univ. of Magdeburg (Germany). Dept. of Mechanical Engineering

    2009-07-01

    Increasing attention has been paid to vibration and noise control in automotive engineering because it contributes to comfort, efficiency and safety. Since the oil pan is a major contributor to power train noise, a study was conducted to design a smart car oil pan with surface-attached piezoelectric actuators for active vibration and noise reduction. Efficient and reliable simulation tools were used along with a virtual model that predicted the performance of the smart oil pan and enabled engineers to compare different sensor-actuator configurations and control algorithms. The model included the passive oil pan, exterior sound field, sensors, actuators and a control algorithm. Due to the interactions between these subsystems the simulation was a coupled multi-field problem involving the fields of structural dynamics, electromechanics, acoustics and control theory. Numerical methods such as the finite element method (FEM) and the boundary element method (BEM) were used to accurately model the structural and acoustic response when actuator forces were applied to the structure. MATLAB software was used to model the oil pan and the piezoelectric actuators. Uncoupled structural FE simulations of the oil pan were first presented to identify the most dominant mode shapes within a frequency range of 0-1200 Hz. The definition of the actuator positions was then performed. A velocity feedback control algorithm was implemented into the electromechanical FE analysis to provide a closed loop model. With velocity feedback control, attenuations of about 24 dB in vibration level and 16 dB in sound pressure level at the resonance frequencies of the most dominant modes of the smart oil pan were achieved. Experimental results were found to be in good agreement with numerical results. 7 refs., 6 figs.

  15. Active control of interior noise within an irregular enclosure under the cooperation of point force and incident wave

    Institute of Scientific and Technical Information of China (English)

    GENG Houcai; RAO Zhushi; HAN Zushun; ZHANG Hualiang

    2002-01-01

    A new modeling method is developed for the active control of interior noise within an irregular three-dimensional cavity under the cooperation of point force and incident wave. The validity of this method is verified by a regular cuboid enclosure. With global and local per-formance functions, good results are obtained in the active control of noise within the irregular enclosure according to numerical investigations.

  16. Characterization of electro-acoustics impedance and its application to active noise control

    Institute of Scientific and Technical Information of China (English)

    HOU Hong; YANG Jianhua

    2004-01-01

    Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to Active Noise Control is demonstrated through a coil driven loudspeaker. A general formula of radiation impedance is derived for two control strategies, according to the criterion of total acoustic power output. The radiation impedances of some commonly used sound sources are calculated. We discuss in detail the relation between variation of the input electrical impedance and radiation impedance for the two control strategies. The measured data of the input electrical impedance from a loudspeaker agree fairly well with theoretical analysis. An AC- bridge circuit is designed in order to measure the weak variation of electrical impedance resulted from radiation impedance. The bridge relative output is unique for a certain control strategy, from which an impedance-based error criterion is then proposed and the implementation of its application to an active control system is analyzed.Numerical results of such criterion are presented. An analogue control system is set up and experiments are carried out in a semi-anechoic chamber to verify the new control approach.

  17. Active control of structure-borne noise. Kotaion no nodo seigyoho ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, N. (Mechanical Engineering Laboratory, Tsukuba (Japan))

    1992-06-01

    This paper describes the active control of structure-borne noise emitted from a vibrating plate. It also presents the mechanism of suppression of a rigid plate vibration from the viewpoint of a feedforward control method. First, in order to control the rigid plate vibration, two kinds of vibration control methods are proposed. One is of a progressive wave type and the other is of a standing wave type. Then, the characteristics of the sound radiated from the controlled plate are made clear. Consequently. it was shown that there existed two types in radiation efficiency, i.e., a peak type and a notch type. For the peak type, the effect of standing wave type control has higher radiation efficiency with the control than without the control, and conversely for the notch type, it has higher one without the control than with the control. Furthermore, a wave visualization system has been constructed. This system made it possible to observe progressive waves propagating on the rigid plate. 11 refs., 14 figs.

  18. Active Noise Control in a Three Dimensional Enclosure Using Multichannel Fuzzy LMS Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Hyun Do [Dankook University (Korea, Republic of); Kim, Kyun Tae [Haitai Electronics R and D Cemter (Korea, Republic of)

    1998-05-01

    In this paper, active noise control(ANC) in an enclosure using multi-channel fuzzy LMS(MCFLMS) algorithm is considered. A new model for a secondary path transfer function, which has common acoustical poles that correspond to resonance properties of an enclosure, is used. Since this model requires far fewer variable parameters to represent secondary path transfer functions than those of conventional all-zero or pole and zero models, it reduces the computational complexity for an active noise control system. A MCFLMS algorithm, where the convergence coefficients of a multi-channel LMS(MCLMS) algorithm is derived by a fuzzy inference engine, is proposed. This algorithm shows better convergence than the existing MCLMS algorithms and it does not require pre-adjustment of convergence parameters, so it could be easily applied to practical ANC systems. Computer simulations and experiments were performed to show the effectiveness of the proposed algorithm in experimental enclosure. The proposed method shows better results in both computer simulations and experiments. (author). 14 refs., 10 figs., 2 tabs.

  19. Filtered-X Affine Projection Algorithms for Active Noise Control Using Volterra Filters

    Directory of Open Access Journals (Sweden)

    Sicuranza Giovanni L

    2004-01-01

    Full Text Available We consider the use of adaptive Volterra filters, implemented in the form of multichannel filter banks, as nonlinear active noise controllers. In particular, we discuss the derivation of filtered-X affine projection algorithms for homogeneous quadratic filters. According to the multichannel approach, it is then easy to pass from these algorithms to those of a generic Volterra filter. It is shown in the paper that the AP technique offers better convergence and tracking capabilities than the classical LMS and NLMS algorithms usually applied in nonlinear active noise controllers, with a limited complexity increase. This paper extends in two ways the content of a previous contribution published in Proc. IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03, Grado, Italy, June 2003. First of all, a general adaptation algorithm valid for any order of affine projections is presented. Secondly, a more complete set of experiments is reported. In particular, the effects of using multichannel filter banks with a reduced number of channels are investigated and relevant results are shown.

  20. 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.

  1. Active vibration control on a quarter-car for cancellation of road noise disturbance

    Science.gov (United States)

    Belgacem, Walid; Berry, Alain; Masson, Patrice

    2012-07-01

    In this paper, a methodology is presented for the cancellation of road noise, from the analysis of vibration transmission paths for an automotive suspension to the design of an active control system using inertial actuators on a suspension to reduce the vibrations transmitted to the chassis. First, experiments were conducted on a Chevrolet Epica LS automobile on a concrete test track to measure accelerations induced on the suspension by the road. These measurements were combined with experimental Frequency Response Functions (FRFs) measured on a quarter-car test bench to reconstruct an equivalent three dimensional force applied on the wheel hub. Second, FRFs measured on the test bench between the three-dimensional driving force and forces at each suspension/chassis linkage were used to characterize the different transmission paths of vibration energy to the chassis. Third, an experimental model of the suspension was constructed to simulate the configuration of the active control system, using the primary (disturbance) FRFs and secondary (control) FRFs also measured on the test bench. This model was used to optimize the configuration of the control actuators and to evaluate the required forces. Finally, a prototype of an active suspension was implemented and measurements were performed in order to assess the performance of the control approach. A 4.6 dB attenuation on transmitted forces was obtained in the 50-250 Hz range.

  2. Numerical simulation and experimental validation of the control mechanism of noise and vibration active control devices by piezoceramic transducers

    Energy Technology Data Exchange (ETDEWEB)

    Miccoli, G. [National Research Council, Cassana (Italy). Earth-Moving Machinery and Off-Road Vehicles Inst.; Concilio, A. [C.I.R.A., Capua (Italy)

    1994-12-31

    The applications till now carried out by this research group in order to actively control structural noise and vibration levels by means of piezoceramic transducers refer to the use and test of simple analogic SISO control systems. These devices work each connected to a couple of sensor/actuator collocated piezoceramics and implement positive feedback control law with self-adaptive variable gain. In order to improve the performance of these control systems and get more insight into their operation, the simulation of the control mechanism itself has been carried out by means of: (a) theoretical analysis of phase and gain characteristics of these devices using finite element (FEM) code (MSC/NASTRAN); (b) experimental validation of the analytical results by means of an on purpose built SISO variable phase and gain control system. On the basis of the experimental results obtained the electronic components of this first SISO control system have been optimized in order to reduce possible instability phenomena.

  3. Active control of counter-rotating open rotor interior noise in a Dornier 728 experimental aircraft

    Science.gov (United States)

    Haase, Thomas; Unruh, Oliver; Algermissen, Stephan; Pohl, Martin

    2016-08-01

    The fuel consumption of future civil aircraft needs to be reduced because of the CO2 restrictions declared by the European Union. A consequent lightweight design and a new engine concept called counter-rotating open rotor are seen as key technologies in the attempt to reach this ambitious goals. Bearing in mind that counter-rotating open rotor engines emit very high sound pressures at low frequencies and that lightweight structures have a poor transmission loss in the lower frequency range, these key technologies raise new questions in regard to acoustic passenger comfort. One of the promising solutions for the reduction of sound pressure levels inside the aircraft cabin are active sound and vibration systems. So far, active concepts have rarely been investigated for a counter-rotating open rotor pressure excitation on complex airframe structures. Hence, the state of the art is augmented by the preliminary study presented in this paper. The study shows how an active vibration control system can influence the sound transmission of counter-rotating open rotor noise through a complex airframe structure into the cabin. Furthermore, open questions on the way towards the realisation of an active control system are addressed. In this phase, an active feedforward control system is investigated in a fully equipped Dornier 728 experimental prototype aircraft. In particular, the sound transmission through the airframe, the coupling of classical actuators (inertial and piezoelectric patch actuators) into the structure and the performance of the active vibration control system with different error sensors are investigated. It can be shown that the active control system achieves a reduction up to 5 dB at several counter-rotating open rotor frequencies but also that a better performance could be achieved through further optimisations.

  4. Vehicle engine sound design based on an active noise control system

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, M. [Siemens VDO Automotive, Auburn Hills, MI (United States)

    2002-07-01

    A study has been carried out to identify the types of vehicle engine sounds that drivers prefer while driving at different locations and under different driving conditions. An active noise control system controlled the sound at the air intake orifice of a vehicle engine's first sixteen orders and half orders. The active noise control system was used to change the engine sound to quiet, harmonic, high harmonic, spectral shaped and growl. Videos were made of the roads traversed, binaural recording of vehicle interior sounds, and vibrations of the vehicle floor pan. Jury tapes were made up for day driving, nighttime driving and driving in the rain during the day for each of the sites. Jurors used paired comparisons to evaluate the vehicle interior sounds while sitting in a vehicle simulator developed by Siemens VDO that replicated videos of the road traversed, binaural recording of the vehicle interior sounds and vibrations of the floor pan and seat. (orig.) [German] Im Rahmen einer Studie wurden Typen von Motorgeraeuschen identifiziert, die von Fahrern unter verschiedenen Fahrbedingungen als angenehm empfunden werden. Ein System zur aktiven Geraeuschbeeinflussung am Ansauglufteinlass im Bereich des Luftfilters modifizierte den Klang des Motors bis zur 16,5ten Motorordnung, und zwar durch Bedaempfung, Verstaerkung und Filterung der Signalfrequenzen. Waehrend der Fahrt wurden Videoaufnahmen der befahrenen Strassen, Stereoaufnahmen der Fahrzeuginnengeraeusche und Aufnahmen der Vibrationsamplituden des Fahrzeugbodens erstellt; dies bei Tag- und Nachtfahrten und bei Tagfahrten im Regen. Zur Beurteilung der aufgezeichneten Geraeusche durch Versuchspersonen wurde ein Fahrzeug-Laborsimulator mit Fahrersitz, Bildschirm, Lautsprecher und mechanischer Erregung der Bodenplatte aufgebaut, um die aufgenommenen Signale moeglichst wirklichkeitsgetreu wiederzugeben. (orig.)

  5. Active control of interior noise in a large scale cylinder using piezoelectric actuators

    Science.gov (United States)

    Lester, H. C.; Silcox, R. J.

    1992-07-01

    The noise reduction effectiveness of two types of control force actuator models has been analytically investigated: (1) a point actuator, and (2) an in-plane, piezoelectric actuator. The actuators were attached to the wall of a simply supported, elastic cylinder closed with rigid end caps. Control inputs to the actuators were determined such that the integrated square of the pressure over the interior of the vibrating cylinder was a minimum. Significant interior noise reductions were achieved for all actuator configurations, but especially for the structurally dominated response. Noise reduction of 9 dB to 26 dB were achieved using point force actuators, as well as localized and extended piezoelectric actuators. Control spillover was found to limit overall performance for all cases. However, the use of extended piezoelectric actuators was effective in reducing control spillover, without increasing the number of control degrees of freedom.

  6. Multiple Iteration of Weight Updates for Least Mean Square Adaptive Filter in Active Noise Control Application

    Directory of Open Access Journals (Sweden)

    Mustafa Rahimie

    2017-01-01

    Full Text Available The method of least mean square (LMS is the commonly used algorithm in Adaptive filter due to its simplicity and robustness in implementation. In Active Noise Control application, a filtered reference signal is used prior to LMS algorithm to overcome the constraint on stability and convergence performance of the system due to the existence of the auxiliary path. This is known as Filtered-X LMS algorithm. In conventional Filtered-X LMS algorithm, each filter weight is updated once on every audio sample. This paper proposes the improved version of Filtered-X LMS algorithm with the use of multiple iteration of filter weight on every sample of audio signal. The proposed work uses field programmable gate arrays to realize real-time simulation on hardware for the noise signal of 500 Hz. Results from the real-time hardware simulations have shown much faster error convergence and better adaptation performance for different selections of learning constant μ, as compared with the conventional method.

  7. Development of adaptive IIR filtered-e LMS algorithm for active noise control

    Institute of Scientific and Technical Information of China (English)

    SUN Xu; MENG Guang; TENG Pengxiao; CHEN Duanshi

    2003-01-01

    Compared to finite impulse response (FIR) filters, infinite impulse response (IIR)filters can match the system better with much fewer coefficients, and hence the computationload is saved and the performance improves. Therefore, it is attractive to use IIR filters insteadof FIR filters in active noise control (ANC). However, filtered-U LMS (FULMS) algorithm, theIIR filter-based algorithm commonly used so far cannot ensure global convergence. A new IIRfilter based adaptive algorithm, which can ensure global convergence with computation loadonly slightly increasing, is proposed in this paper. The new algorithm is called as filtered-eLMS algorithm since the error signal of which need to be filtered. Simulation results show thatthe FELMS algorithm presents better performance than the FULMS algorithm.

  8. Controlling kilometre-scale interferometric detectors for gravitational wave astronomy: Active phase noise cancellation using EOMs

    Science.gov (United States)

    Arnaud, N.; Balembois, L.; Bizouard, M. A.; Brisson, V.; Casanueva, J.; Cavalier, F.; Davier, M.; Frey, V.; Hello, P.; Huet, D.; Leroy, N.; Loriette, V.; Maksimovic, I.; Robinet, F.

    2017-02-01

    The second generation of Gravitational waves detectors are kilometric Michelson interferometers with additional recycling Fabry-Perot cavities on the arms and ​the addition of two more recycling cavities to enhance their sensitivity, with the particularity that all the mirrors are suspended. In order to control them a new technique, based on the use of auxiliary lasers, has been developed to bring the interferometer to its working point, with all the cavities on their resonance, in an adiabatic way. The implementation of this technique in Advanced Virgo is under preparation and the propagation of a stable laser through a 3-km optical fibre is one of the most problematic issues. A new technique of active phase noise cancellation based on the use of Electro Optical Modulators has been developed, and a first prototype has been successfully tested.

  9. Active Noise Control Using a Functional Link Artificial Neural Network with the Simultaneous Perturbation Learning Rule

    Directory of Open Access Journals (Sweden)

    Ya-li Zhou

    2009-01-01

    Full Text Available In practical active noise control (ANC systems, the primary path and the secondary path may be nonlinear and time-varying. It has been reported that the linear techniques used to control such ANC systems exhibit degradation in performance. In addition, the actuators of an ANC system very often have nonminimum-phase response. A linear controller under such situations yields poor performance. A novel functional link artificial neural network (FLANN-based simultaneous perturbation stochastic approximation (SPSA algorithm, which functions as a nonlinear mode-free (MF controller, is proposed in this paper. Computer simulations have been carried out to demonstrate that the proposed algorithm outperforms the standard filtered-x least mean square (FXLMS algorithm, and performs better than the recently proposed filtered-s least mean square (FSLMS algorithm when the secondary path is time-varying. This observation implies that the SPSA-based MF controller can eliminate the need of the modeling of the secondary path for the ANC system.

  10. Hybrid Active-Passive Systems for Control of Aircraft Interior Noise

    Science.gov (United States)

    Fuller, Chris R.

    1999-01-01

    Previous work has demonstrated the large potential for hybrid active-passive systems for attenuating interior noise in aircraft fuselages. The main advantage of an active-passive system is, by utilizing the natural dynamics of the actuator system, the control actuator power and weight is markedly reduced and stability/robustness is enhanced. Three different active-passive approaches were studied in the past year. The first technique utilizes multiple tunable vibration absorbers (ATVA) for reducing narrow band sound radiated from panels and transmitted through fuselage structures. The focus is on reducing interior noise due to propeller or turbo fan harmonic excitation. Two types of tunable vibration absorbers were investigated; a solid state system based upon a piezoelectric mechanical exciter and an electromechanical system based upon a Motran shaker. Both of these systems utilize a mass-spring dynamic effect to maximize tile output force near resonance of the shaker system and so can also be used as vibration absorbers. The dynamic properties of the absorbers (i.e. resonance frequency) were modified using a feedback signal from an accelerometer mounted on the active mass, passed through a compensator and fed into the drive component of the shaker system (piezoelectric element or voice coil respectively). The feedback loop consisted of a two coefficient FIR filter, implemented on a DSP, where the input is acceleration of tile ATVA mass and the output is a force acting in parallel with the stiffness of the absorber. By separating the feedback signal into real and imaginary components, the effective natural frequency and damping of the ATVA can be altered independently. This approach gave control of the resonance frequencies while also allowing the simultaneous removal of damping from the ATVA, thus increasing the ease of controllability and effectiveness. In order to obtain a "tuned" vibration absorber the chosen resonant frequency was set to the excitation

  11. Convergence analysis of the Filtered-U LMS algorithm for active noise control in case perfect cancellation is not possible

    NARCIS (Netherlands)

    Fraanje, P.R.; Verhaegen, M.; Doelman, N.J.

    2003-01-01

    The Filtered-U LMS algorithm, proposed by Eriksson for active noise control applications, adapts the coefficients of an infinite-impulse response controller. Conditions for global convergence of the Filtered-U LMS algorithm were presented by Wang and Ren (Signal Processing, 73 (1999) 3) and Mosquera

  12. Active noise control - Piezoceramic actuators in fluid/structure interaction models

    Science.gov (United States)

    Banks, H. T.; Fang, W.; Smith, R. C.

    1991-01-01

    A model for a 2-D acoustic cavity with a flexible boundary (a beam) controlled via piezoceramic patches producing bending moments in the beam is considered. The associated control problem for this fluid/structure interaction system to reduce the acoustic pressure in the cavity involves unbounded control inputs. Approximation methods in the context of an LQR state space formulation are discussed, and numerical results are presented to demonstrate the effectiveness of this approach in computing feedback controls for noise reduction.

  13. 基于DSP的有源噪声控制系统设计%Active Noise Control Based on DSP

    Institute of Scientific and Technical Information of China (English)

    马永炜; 缑新科; 杜先君; 任崇玉

    2012-01-01

    The feed-forwaid adaptive active noise control (AANC) system is presented. First, the hardware project of the system is brought forward by selecting TMS320C5509 DSP as the controller. Second, using the mixed language, the active noise real-time control system is realized, based on the FXLMS algorithm. It's proved that a good noise cancellation is achieved by the experiment%基于有源噪声控制算法,设计出一种有源噪声控制器.以TMS320C5509为核心,给出了系统的硬件解决方案,并利用混合编程在硬件系统上实现了基于LMS算法的有源噪声实时控制.实验结果表明,系统取得了良好的降噪效果.

  14. A Control Source Structure of Single Loudspeaker and Rear Sound Interference for Inexpensive Active Noise Control

    Directory of Open Access Journals (Sweden)

    Yasuhide Kobayashi

    2010-01-01

    phase-lag is imposed by the Swinbanks' source and the rear sound interference. Thirdly, effects on control performances of control source structures are examined by control experiments with robust controllers.

  15. 汽车车内制动噪声主动控制%Active Noise Control of Automotive Interior Braking Noise

    Institute of Scientific and Technical Information of China (English)

    冯天培; 孙跃东; 王岩松; 刘宁宁

    2016-01-01

    Low-frequency components of braking noise usually dominate the internal noise for some kinds of automobiles. Since the low-frequency noise has high energy, the strong interior noise will reduce the comfort for the passengers. In this paper, the braking noises at the driver’s ears in three different cars travelling at 60km/h in emergency braking were collected and analyzed in time-frequency domain. Results of analysis agreed well with the real ride-perception in a testing car. Then, the active braking noise control simulation using adaptive LMS algorithm was implemented. The results show that the low-frequency noise, especially in the range of 20 Hz-50 Hz, is greatly eliminated.%部分汽车制动时的车内噪声以低频成分占主导。低频噪声能量大,车内较强的低频制动噪声会给乘员带来不舒适的乘坐感受,降低车辆的乘坐舒适性。采集三辆轿车车内60 km/h紧急制动时司机位双耳处噪声信号并进行时-频域分析,分析结果与实车试验乘坐感受一致,接着运用低频噪声消噪效果较好的主动噪声控制方法,结合自适应LMS算法对样本信号进行消噪仿真实验,制动噪声低频部分得到较大的抑制,特别是在20 Hz~50 Hz低频带内,噪声能量衰减明显。

  16. Active Noise Control for Narrow-band and Broad-band Signals Using Q-Learning Technique

    Directory of Open Access Journals (Sweden)

    B. Raeisy

    2013-06-01

    Full Text Available The acoustic noise pollution is one of the serious disasters in the current industrialized life. Though traditional solutions based on noise absorption have many different applications, but these methods have low performance for low frequency noises. Active Noise Control (ANC has been introduced to resolve this problem. In this paper, a new active method is introduced for suppressing acoustic noises based on the reinforcement learning. To achieve this, an algorithm to control periodic noises is suggested. Then, the method is developed further to deal with multi-tonal signals with a large number of harmonics. At the next step, the broad-band signals are considered. The problem is broken into some sub-problems in frequency domain and each is solved via a reinforcement learning approach. In all of the proposed techniques no model for the environment is needed. Combining the reinforcement learning and the traditional methods in ANC for broad-band signals is a new line research considered here. This combination could increase the speed of the response, but some information of the dynamics of the environment is needed. This will cause the system to become compatible with gradual changes of the environment. Simulation results show the effectiveness of the proposed approach.

  17. 多通道有源噪声控制系统设计%Reduction of Noise in Chinese Y-7 Aircraft Using Active Noise Control (ANC)

    Institute of Scientific and Technical Information of China (English)

    吴亚锋; 黎中伟; 任辉; 李江红

    2001-01-01

    Active noise control, as applied to engineering projects, began around 1990. We designed a multi-channel active noise control (ANC) system for reducing the noise in front cabin in Chinese Y-7 propeller driven aircraft. In ANC applications, in order to reduce effectively the noise level in a large space, we have to match at any time the generated secondary sound field with the original primary sound field, so that a percentage of the entire primary noise field is effectively cancelled out by the entire secondary noise field. Via analyzing ANC time sequences, we developed a multi-channel adaptive control system that can simultaneously detect multiple error inputs and produce multiple canceling outputs. Our system consists of PC as main controller, TMS320-C30 DSP chip as slave processor, 16 A/D input channels and 8 D/A output channels. Applying our system to Chinese Y-7 aircraft appears to be successful; test results show that noise level of Y-7′s blade pass frequency (BPF) and its secondary harmonic frequency (2BPF) are attenuated by 13.4 dB and 5.5 dB respectively. Work remains to be done before our system becomes a part of Y-7 aircraft in actual flights.%基于实时数字信号处理系统理论,讨论有源噪声控制系统的电子设计方法。通过对控制时序的分析,设计了一实时多通道自适应控制系统,该系统以PC为主控机,以DSP TMS320-C30为从处理机,具有多路传感器同时输入和扬声器同时输出通道。该系统被应用于国产某型螺桨飞机的舱内噪声控制,取得了满意的降噪效果。

  18. The use of active vibration control for the reduction of ICE interior noise

    Energy Technology Data Exchange (ETDEWEB)

    Schirmacher, R. [Mueller-BBM GmbH - Beratende Ingenieure fuer Akustik, Planegg (Germany)

    2001-07-01

    First generation ICE high speed trains show a disturbing low frequency noise of about 100 Hz audible inside the coaches. It is excited by unround wheels, propagates via the bogie to the body of the coach and is finally radiated as airborne sound. A mixed concept of active suspension at the bogie in connection with adaptive residual noise minimisation inside the passenger compartment is successfully applied to the problem. A prototype system utilizing piezo ceramic actuators was installed and tested on the rolling rig of Deutsche Bahn in Munich. The noise level reductions at single harmonics were more than 12 dB averaged over the whole compartment and more than 20 dB at single seats. Measurement results and practical experiences with the system are reported. (orig.)

  19. Control strategies for aircraft airframe noise reduction

    Institute of Scientific and Technical Information of China (English)

    Li Yong; Wang Xunnian; Zhang Dejiu

    2013-01-01

    With the development of low-noise aircraft engine,airframe noise now represents a major noise source during the commercial aircraft's approach to landing phase.Noise control efforts have therefore been extensively focused on the airframe noise problems in order to further reduce aircraft overall noise.In this review,various control methods explored in the last decades for noise reduction on airframe components including high-lift devices and landing gears are summarized.We introduce recent major achievements in airframe noise reduction with passive control methods such as fairings,deceleration plates,splitter plates,acoustic liners,slat cove cover and side-edge replacements,and then discuss the potential and control mechanism of some promising active flow control strategies for airframe noise reduction,such as plasma technique and air blowing/suction devices.Based on the knowledge gained throughout the extensively noise control testing,a few design concepts on the landing gear,high-lift devices and whole aircraft are provided for advanced aircraft low-noise design.Finally,discussions and suggestions are given for future research on airframe noise reduction.

  20. Real-time Kalman filter implementation for active feedforward control of time-varying broadband noise and vibrations

    NARCIS (Netherlands)

    Ophem, S. van; Berkhoff, A.P.

    2012-01-01

    Tracking behavior and the rate of convergence are critical properties in active noise control applications with time-varying disturbance spectra. As compared to the standard filtered-reference Least Mean Square (LMS) algorithm, improved convergence can be obtained with schemes based on preconditioni

  1. Performance of a multi-channel adaptive Kalman algorithm for active noise control of non-stationary sources

    NARCIS (Netherlands)

    Ophem, S. van; Berkhoff, A.P.

    2012-01-01

    Commonly used adaptive algorithms which determine the coefficients of a finite impulse response feed-forward filter in an active noise control application, as the filtered reference least mean squares algorithm, are not performing well when the sound source is non-stationary. A multiple input and

  2. Real-time Kalman filter implementation for active feedforward control of time-varying broadband noise and vibrations

    NARCIS (Netherlands)

    Ophem, S. van; Berkhoff, A.P.

    2012-01-01

    Tracking behavior and the rate of convergence are critical properties in active noise control applications with time-varying disturbance spectra. As compared to the standard filtered-reference Least Mean Square (LMS) algorithm, improved convergence can be obtained with schemes based on

  3. A Model Predictive Algorithm for Active Control of Nonlinear Noise Processes

    Directory of Open Access Journals (Sweden)

    Qi-Zhi Zhang

    2005-01-01

    Full Text Available In this paper, an improved nonlinear Active Noise Control (ANC system is achieved by introducing an appropriate secondary source. For ANC system to be successfully implemented, the nonlinearity of the primary path and time delay of the secondary path must be overcome. A nonlinear Model Predictive Control (MPC strategy is introduced to deal with the time delay in the secondary path and the nonlinearity in the primary path of the ANC system. An overall online modeling technique is utilized for online secondary path and primary path estimation. The secondary path is estimated using an adaptive FIR filter, and the primary path is estimated using a Neural Network (NN. The two models are connected in parallel with the two paths. In this system, the mutual disturbances between the operation of the nonlinear ANC controller and modeling of the secondary can be greatly reduced. The coefficients of the adaptive FIR filter and weight vector of NN are adjusted online. Computer simulations are carried out to compare the proposed nonlinear MPC method with the nonlinear Filter-x Least Mean Square (FXLMS algorithm. The results showed that the convergence speed of the proposed nonlinear MPC algorithm is faster than that of nonlinear FXLMS algorithm. For testing the robust performance of the proposed nonlinear ANC system, the sudden changes in the secondary path and primary path of the ANC system are considered. Results indicated that the proposed nonlinear ANC system can rapidly track the sudden changes in the acoustic paths of the nonlinear ANC system, and ensure the adaptive algorithm stable when the nonlinear ANC system is time variable.

  4. Adjoint LMS (ALMS Algorithm Based Active Noise Control with Feedback Path Modeling

    Directory of Open Access Journals (Sweden)

    U Ramachandraiah,

    2010-12-01

    Full Text Available In active noise control (ANC systems, there exists an inherent feedback from the loudspeaker to the primary microphone. Adjoint least mean square (ALMS algorithm is known to be an alternative to the widely used filtered x LMS (FxLMS for reducing the computational complexity and memory requirements, especially in the case of multi-channel systems. Further FxLMS algorithm is based on the assumptionthat the order of the weighing filter and secondary path can be commuted which is not always true in practice. Though ALMS do not make such an assumption, neither FxLMS nor the ALMS algorithms onsider the feedback path effect that is inherent in ANC systems.We propose a feedback ANC system based on ALMS algorithm which is analogous to the system based on FxLMS. Detailed computational complexity analysis for addition and multiplication requirements ispresented and are compared with those of its counterpart to establish its usefulness. Simulation results show the convergence characteristics of the ALMS based ANC with feedback path modeling is on par with that based on FxLMS.

  5. 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.

  6. Optimal virtual sensing for active noise control in a rigid-walled acoustic duct

    Science.gov (United States)

    Petersen, Dick; Zander, Anthony C.; Cazzolato, Ben S.; Hansen, Colin H.

    2005-11-01

    The performance of local active noise control systems is generally limited by the small sizes of the zones of quiet created at the error sensors. This is often exacerbated by the fact that the error sensors cannot always be located close to an observer's ears. Virtual sensing is a method that can move the zone of quiet away from the physical location of the transducers to a desired location, such as an observer's ear. In this article, analytical expressions are derived for optimal virtual sensing in a rigid-walled acoustic duct with arbitrary termination conditions. The expressions are derived for tonal excitations, and are obtained by employing a traveling wave model of a rigid-walled acoustic duct. It is shown that the optimal solution for the virtual sensing microphone weights is independent of the source location and microphone locations. It is also shown that, theoretically, it is possible to obtain infinite reductions at the virtual location. The analytical expressions are compared with forward difference prediction techniques. The results demonstrate that the maximum attenuation, that theoretically can be obtained at the virtual location using forward difference prediction techniques, is expected to decrease for higher excitation frequencies and larger virtual distances.

  7. Experimental investigation of different active noise control concepts applied to a passenger car equipped with an active windshield

    Science.gov (United States)

    Misol, M.; Algermissen, S.; Monner, H. P.

    2012-05-01

    The main purpose of this work is the implementation and experimental investigation of different active structural acoustic control (ASAC) concepts for the reduction of interior noise in an automobile passenger compartment. For the control experiments, a medium-class test car was used, which had been equipped with an active windshield. The active windshield consists of the serial-production laminated glass pane augmented with piezoceramic patch-transducers applied to the blackened rim of the windshield. A multi-reference test provided measurement data for the identification of a local discrete-time state-space model (SSM). The subsequent acquisition of frequency response functions (FRF) by way of using the same actuators but measuring on a much finer grid provided the database for the formulation of a least-squares problem to derive a global system model. Based on the local and global discrete-time SSMs, different controllers were designed and experimentally realized. The comparison of the vibration levels in open- and closed-loop showed a global reduction of 5-7 dB in the acoustically relevant frequency band containing the second and third structural resonance of the windshield system. The occurrence of complex operational deflection shapes (ODS) was identified as the main limitation concerning the disturbance rejection of the active system. The acoustic performance of the ASAC system is reflected in a reduction up to 15 dB in sound pressure level (SPL).

  8. Improvement of vibration and noise by applying analysis technology. Development of active control technique of engine noise in a car cabin. Kaiseki gijutsu wo oyoshita shindo-soon no kaizen. Shashitsunai engine soon akutibu seigyo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, H.; Nakao, N.; Butsuen, T. (Matsuda Motor Corp., Hiroshima (Japan). Technology Research Inst.)

    1994-06-01

    It is difficult to reduce engine noise which is principal noise in a car cabin without producing an adverse effect on low cost production. Active noise control technique (ANC) has been developed to reduce engine noise compatible with low cost production. This paper discusses its control algorithm and the system configuration and presents experimental results. The filtered-x least mean square method is a well-known ANC algorithm, however, it often requires large amount of calculation exceeding the present capacity of a digital signal processor. An effective ANC algorithm is developed by the use of the repetitiveness of the engine noise. This paper describes the basic theory of the control algorithm, the extension to a multiple input and output system, the system configuration and experimental results. A noise control system with three microphones is designed with consideration of the spatial distribution of the noise and reduces noise in the whole cabin by 8dB(A) in the largest case. Active noise control technique is applicable to many areas and can be used for the reduction of noise and vibration other than engine noise. 5 refs., 7 figs., 1 tab.

  9. Adjusting phenotypes by noise control.

    Directory of Open Access Journals (Sweden)

    Kyung H Kim

    2012-01-01

    Full Text Available Genetically identical cells can show phenotypic variability. This is often caused by stochastic events that originate from randomness in biochemical processes involving in gene expression and other extrinsic cellular processes. From an engineering perspective, there have been efforts focused on theory and experiments to control noise levels by perturbing and replacing gene network components. However, systematic methods for noise control are lacking mainly due to the intractable mathematical structure of noise propagation through reaction networks. Here, we provide a numerical analysis method by quantifying the parametric sensitivity of noise characteristics at the level of the linear noise approximation. Our analysis is readily applicable to various types of noise control and to different types of system; for example, we can orthogonally control the mean and noise levels and can control system dynamics such as noisy oscillations. As an illustration we applied our method to HIV and yeast gene expression systems and metabolic networks. The oscillatory signal control was applied to p53 oscillations from DNA damage. Furthermore, we showed that the efficiency of orthogonal control can be enhanced by applying extrinsic noise and feedback. Our noise control analysis can be applied to any stochastic model belonging to continuous time Markovian systems such as biological and chemical reaction systems, and even computer and social networks. We anticipate the proposed analysis to be a useful tool for designing and controlling synthetic gene networks.

  10. 管道电机噪声有源控制系统研究%Experimental research of duct active noise control for motor operating noise

    Institute of Scientific and Technical Information of China (English)

    刘会灯; 邱阿瑞

    2011-01-01

    针对直流电机运行噪声的频谱特点,设计管道电机噪声有源控制的物理系统和软件硬件系统.对直流电机运行噪声,通过实验进行单通道有源噪声控制算法主要参数包括泄漏参数、迭代步长和滤波器长度的最优化设计.根据优化后的算法参数,进行管道电机噪声单通道和多通道有源控制实验.实验结果表明,电机转速为1 200r/min和1 500r/min时,对于单通道和多通道有源噪声控制系统,管道下游最大的降噪量分别为14.8dB和17.9dB以及16.42dB和19.75dB, 降噪效果也表明有源噪声控制系统能有效地降低电机运行噪声.%A duct active noise control (ANC) experimental platform including the physical system, hardware and software system was designed to control a DC motor operating noise. The parameters for the single channel ANC algorithms were optimized to achieve the maximum noise reduction when the practical DC motor operating noise was applied. With these optimized algorithm parameters, several experiments were conducted for both single channel and multi-channel duct ANC system to control the DC motor operating noise. The experimental results show that the maximum sound pressure level (SPL) reductions downstream of the duct are about 14. 8dB and 17.9dB for the single channel duct ANC system, 16. 42dB and 19. 72dB for the multi-channel duct ANC system when the DC motor operates at the speed of 1200r/min and 1500r/min respectively, which indicates that ANC can be a feasible way to reduce the motor operating noise.

  11. Modified-filtered-u LMS algorithm for active noise control and its application to a short acoustic duct

    Science.gov (United States)

    Kim, Ho-Wuk; Park, Hong-Sug; Lee, Sang-Kwon; Shin, Kihong

    2011-01-01

    This paper presents a new adaptive algorithm for active noise control (ANC) that can be effectively applicable to a short acoustic duct, such as the intake system of an automobile engine, where the stability and fast convergence of the ANC system is particularly important. The new algorithm, called the modified-filtered-u LMS algorithm (MFU-LMS), is developed based on the recursive filtered-u LMS algorithm (FU-LMS) incorporating the simple hyper-stable adaptive recursive filter (SHARF) to ensure the control stability and the variable step size to enhance the convergence rate. The MFU-LMS algorithm is implemented by purely experimental ways, and is applied to active control of noise in a short acoustic duct, and is validated using two experimental cases of which the primary noise sources are a sinusoidal signal embedded in white noise and a chirp signal. The experimental results demonstrate that the proposed MFU-LMS algorithm gives a considerably better performance than other conventional algorithms, such as the filtered-x LMS (FX-LMS) and the FU-LMS algorithms.

  12. Study on the active noise control method and the effect of noise reduction due to the multi-connected branch dusts. Gyakuiso no fukaon ni yoru soon seigyoho no kento to tarengata bunkikan ni yoru soon keigen koka

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Kiyoatsu.

    1989-04-01

    This paper reports the results of experimental studies on the utility of the active noise control method, and the effects of the multi-connected branch pipes silencer, concerning the reduction of noise. In the experiments of active noise control by using ducts, when the canceling sound was produced by the speaker set at the end of the short-length pipe corresponding to the one forth wave-length, the sound pressure of canceling noise was less one sixth as compared with setting the speaker at the wall of pipe. The noise reduction quantity to the random noise by the active noise control method was about as much as 15db. This method is not adaptable for noise with wide ranges of frequency. A branch pipe silencers, when it was used as multi-connected branch pipe, could extend the bounds of noise frequency which was able to be reduced and could increase the noise reduction quality. This silencer can deal with the fluctuation of frequency od noise and has higher practicability. 10 refs., 21 figs.

  13. Neural Control Adaptation to Motor Noise Manipulation

    Directory of Open Access Journals (Sweden)

    Christopher J Hasson

    2016-03-01

    Full Text Available Antagonistic muscular co-activation can compensate for movement variability induced by motor noise at the expense of increased energetic costs. Greater antagonistic co-activation is commonly observed in older adults, which could be an adaptation to increased motor noise. The present study tested this hypothesis by manipulating motor noise in twelve young subjects while they practiced a goal-directed task using a myoelectric virtual arm, which was controlled by their biceps and triceps muscle activity. Motor noise was increased by increasing the coefficient of variation of the myoelectric signals. As hypothesized, subjects adapted by increasing antagonistic co-activation, and this was associated with reduced noise-induced performance decrements. A second hypothesis was that a virtual decrease in motor noise, achieved by smoothing the myoelectric signals, would have the opposite effect: co-activation would decrease and motor performance would improve. However, the results showed that a decrease in noise made performance worse instead of better, with no change in co-activation. Overall, these findings suggest that the nervous system adapts to virtual increases in motor noise by increasing antagonistic co-activation, and this preserves motor performance. Reducing noise may have failed to benefit performance due to characteristics of the filtering process itself, e.g. delays are introduced and muscle activity bursts are attenuated. The observed adaptations to increased noise may explain in part why older adults and many patient populations have greater antagonistic co-activation, which could represent an adaptation to increased motor noise, along with a desire for increased joint stability.

  14. Numerical methods to predict the performance of passive and active noise control measures

    Energy Technology Data Exchange (ETDEWEB)

    Fyfe, K. R. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering

    1996-08-01

    The two major categories of acoustic modelling methods, which permit a very detailed analysis of both the current operating state and any proposed modifications to noise control equipment, were reviewed. One of the categories is based on geometrical principles which treats sound propagation as a series of rays with diffraction principles to account for edge effects. The wave-based method, on the other hand, models the true physical nature of sound, including interference and scattering. The finite element method (well suited for the study of enclosures) and the boundary element method (for finite and infinite domain analysis) which belong to this category, were emphasized in this paper, as methods of choice for predicting sound fields in enclosed and exterior domains. The theoretical basis of each method was sketched, limitations were described, and examples of their application in such areas as barrier design and furnace mufflers, were provided. 11 refs., 15 figs.

  15. Re-active Passive (RAP) Devices for Control of Noise Transmission through a Panel

    Science.gov (United States)

    Carneal, James P.; Giovanardi, Marco; Fuller, Chris R.; Palumbo, Daniel L.

    2008-01-01

    Re-Active Passive (RAP) devices have been developed to control low frequency (RAP device uses passive constrained layer damping to cover the relatively high frequency range (>200 Hz), reactive distributed vibration absorber) to cover the medium frequency range (75 to 250 Hz), and active control for controlling low frequencies (RAP devices were able to increase the overall broadband (15-1000 Hz) transmission loss by 9.4 dB. These three devices added a total of 285 grams to the panel mass of 6.0 kg, or approximately 5%, not including control electronics.

  16. Still in Womb: Intrauterine Acoustic Embedded Active Noise Control for Infant Incubators

    Directory of Open Access Journals (Sweden)

    Lichuan Liu

    2008-01-01

    effect”, that is, by using intrauterine and maternal heart sounds, proven to be beneficial to infant health, for soothing the infant and masking the residual noise. A computer model for audio-integrated noise cancellation utilizing experimentally measured transfer functions is developed for simulations using real medical equipment noise. The simulation of the audio integrated ANC system produced optimal results and the system was further validated by real-time experiments to be robust and efficient.

  17. Active Noise Control in Ventilation Duct A Prototype for Remote Laboratory

    OpenAIRE

    Muthusamy, Dineshkumar; Ahmad,Waqas

    2012-01-01

    Remote laboratories using real equipments for engineering studies is becoming popular in recent time. Blekinge Institute of Technology (BTH), Sweden has pioneered developing remote laboratories through VISIR project and its collaboration with other universities. Active control of sound and vibration is one area in which BTH has substantial research background and provides courses like adaptive signal processing, sound and vibration analysis, optimum signal processing and so on. The fact that ...

  18. 车内噪声主动控制变步长LMS算法%Active Noise Control for Vehicle Interior Noise Using Variable Incremental Step LMS Algorithm

    Institute of Scientific and Technical Information of China (English)

    余荣平; 张心光; 王岩松; 郭辉

    2015-01-01

    通过对轨道车辆车内含噪样本数据的分析,应用步长因子μ(n)与误差信号e(n)呈正弦函数关系的变步长LMS算法。分别对自适应滤波器中的权向量按照最速下降算法进行更新,并利用建立的自适应滤波器进行车内噪声主动控制。结果表明,提出的变步长LMS算法解决了LMS算法因固定步长不能同时兼顾算法收敛速度和稳态误差的固有缺陷,具有更快的算法收敛速度和较小的稳态误差。%By analyzing the noise signal sample inside the railway vehicle, the plain LMS algorithm and the LMS algo-rithm with variable-incremental-steps were applied respectively to update the weight vectors in the adaptive filtering based on the steepest descent algorithm. The relation between step factor μ(n) and error signal e(n) is a sinusoidal function in the variable-step LMS algorithm. The adaptive filter was used for active internal noise control for the vehicle. Result shows that the proposed variable-step LMS algorithm can overcome the inherent contradiction in the plain LMS algorithm between al-gorithm convergence speed and steady-state error, and has faster algorithm convergence speed and less steady-state error si-multaneously.

  19. A local active noise control system based on a virtual-microphone technique for railway sleeping vehicle applications

    Science.gov (United States)

    Diaz, J.; Egaña, J. M.; Viñolas, J.

    2006-11-01

    Low-frequency broadband noise generated on a railway vehicle by the wheel-rail interaction could be a big annoyance for passengers in sleeping cars. Low-frequency acoustic radiation is extremely difficult to attenuate by using passive devices. In this article, an active noise control (ANC) technique has been proposed for this purpose. A three-dimensional cabin was built in the laboratory to carry out the experiments. The proposed scheme is based on a Filtered-X Least Mean Square (FXLMS) control algorithm, particularised for a virtual-microphone technique. Control algorithms were designed with the Matlab-Simulink tool, and the Real Time Windows Target toolbox of Matlab was used to run in real time the ANC system. Referring to the results, different simulations and experimental performances were analysed to enlarge the silence zone around the passenger's ear zone and along the bed headboard. Attenuations of up to 20 and 15 dB(A) (re:20 μPa) were achieved at the passenger's ear in simulations and in experimental results, respectively.

  20. Multi-Objective Genetic Algorithm Optimisation Approach for the Geometrical Design of an Active Noise Control Systems

    Directory of Open Access Journals (Sweden)

    N. Jafferi

    2009-09-01

    Full Text Available This paper focuses on the geometrical design of active noise control (ANC in free- field propagation medium. The development and performance assessment uses genetic optimisation techniques to arrange system components so as to satisfy several performance requirements, such as physical extent of cancellation, controller design restriction and system stability. The ANC system design can be effectively addressed if it is considered as multi – objective optimisation problems. The multi-objective genetic algorithms (MOGAs are well suited to the design of an ANC system and the approach used for it is based on a multi - objective method, with which the physical extent of cancellation and relative stability assessment are dealt with simultaneously.

  1. 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.

  2. First investigation on the applicability of an active noise control system on a tracked tractor without cab

    Directory of Open Access Journals (Sweden)

    Daniele Pochi

    2013-09-01

    Full Text Available In last years, several research teams pointed their attention on the application of active noise control systems (ANC inside the cabs of agricultural tractor, with the purpose of reducing the driver exposition to noise, that is only partially controlled by the frame of the cab. This paper reports the results of a first experience that aimed at verifying the applicability of an ANC on a medium-high power, tracked tractor without cab. The tested tractor was a Fiat Allis 150 A, equipped with rear power take off, used in the execution of deep primary tillage in compact soils. It is a tracked tractor without cab, with maximum power of 108.8 kW at 1840 min–1 of the engine. The ANC consists of a control unit box based on a digital signal processor (DPS, two microphones, two speakers and a power amplifier. The instrumentation used in noise data collecting and processing consisted of a multichannel signal analyzer (Sinus - Soundbook, a ½” microphone capsule and an acoustic calibrator, both Bruel & Kjaer. The study aimed at evaluating the behaviour of the ANC by means of tests carried out under repeatable conditions, characterized by pre-defined engine speed values. Three replications have been made for each engine speed. The sampling time was 30 s. Two series of tests were performed in order to compare the results observed with the ANC on and off. The engine speed adopted in the study ranged from 600 min– 1, up to 2000 min–1 (maximum speed with steps of 100 min–1. The ANC proved to be effective in the interval of speed between 1400 and 1700 min–1, where the samplings have been intensified, adopting steps of 50 min–1. In such an interval, the attenuation observed with the ANC system on appeared evident both as weighed A sound pressure level (from 1.29 up to 2.46 dB(A and linear (from 4.54 up to 8.53 dB. The best performance has been observed at the engine speed of 1550 min–1, with attenuations, respectively of 2.46 dB(A and 7.67 d

  3. Substation noise intelligent prediction and active control%变电站噪声智能预测及其主动控制

    Institute of Scientific and Technical Information of China (English)

    姜鸿羽; 马宏忠; 姜宁; 李凯

    2014-01-01

    针对变电站噪声有源控制技术中存在的算法性能较差和易受周边环境影响的问题,本文利用人工神经网络、小波技术及遗传算法对该技术进行改进。首先结合小波技术和人工神经网络来预测噪声控制系统的参考输入信号,然后根据小波去噪原理滤除进入误差传感器的混合噪声中由周边环境引起的高频干扰噪声,并将剩余噪声反馈至系统控制器中,最后利用遗传算法优化控制器中小波神经网络的参数,实现变电站噪声的最佳控制。对变电站内变压器振动和噪声数据进行仿真,结果表明改进后的方法有效地提高了系统的噪声跟踪速度、降噪量及稳定性,可以使变电站降噪达到满意的效果。%In view of the deficiencies of substation noise active control technology , such as the poor performance of filtering algorithms and susceptible to the surrounding environment , this article uses artificial neural network , wave-let technology and genetic algorithm to improve the noise active control technology .First, using wavelet technology and artificial neural network algorithm the noise control system ’ s reference input signal is predicted .Then , accord-ing to the principle of wavelet de-noising high-frequency interference noise caused by the surrounding environment is removed which is included in the mixed noise into the error sensor , and the residual noise is fed back to the sys-tem controller.Finally, using genetic algorithm the parameters of wavelet neural network in the system controller are optimized , and optimal control of substation noise is achieved .Through the simulation of substation transformer vibration and noise data , the results show that the improved method can effectively improve the system noise track-ing speed , noise reduction and system stability , and has better suppression effect for substation noise .

  4. Developing situation on active control of vibration and noise%国外振动噪声有源控制技术发展现状

    Institute of Scientific and Technical Information of China (English)

    刘小玲; 王旭; 郭莹; 刘亚凤

    2011-01-01

    With the development of the economy,noise pollution is more and more realized to be a major concern in modern industrial societies. Traditionally, the reduction of structure-borne sound is achieved by means of passive methods. These methods include using damping materials, vibration isolation,and vibration absorber. Passive techniques give good performance in the mid and high frequency range.Unfortunately ,the added mass or volume required to reduce low frequency noise is often impractical. With the advances in digital computers, active control methods have emerged as practical alternatives to passive methods for reducing unwanted noise in the low frequency range. Active noise control has become a research hotspot in the field of modern vibration and noise control. This paper presents the importance of the active noise control, then analyses the development of active noise control in America, the UK and Australia.%随着经济的发展,噪声污染已成为工业社会主要关心的问题.传统的噪声控制主要采用被动的方法,如使用阻尼材料、隔振、吸振.被动控制在中高频段能起到很好的效果,但在低频段效果很不理想.随着电子技术的发展,作为用来替代被动控制以减少低频段噪声的有源控制方法出现了,并且逐渐成为现代振动噪声控制领域的研究热点.本文主要介绍了有源控制技术的重要性,以及该技术在美国、英国和澳大利亚等国家的发展现状.

  5. 自适应滤波在有源消声中的应用%Application of adaptive filter in active noise control

    Institute of Scientific and Technical Information of China (English)

    于华民; 朱海潮; 施引; 吴正国

    2001-01-01

    从分析有源消声的难点出发,综述了自适应滤波算法在有源消声中的应用,给出了相应的实例.对自适应滤波在有源消声中应用的未来发展趋势作了展望.%With focus on the difficulties of ANC(active noise control), the application of adaptive filter in active noise control is reviewed, and some practical examples are also displayed. Finally, prospect of adaptive filter in ANC is proposed.

  6. Noise in the Library: Effects and Control.

    Science.gov (United States)

    Eagan, Ann

    1991-01-01

    Describes the physiological and psychological effects of noise in libraries and suggests methods of controlling noise from telephones, computers, printers, and photocopiers. Hearing loss and stress-related problems are discussed, the effects of noise on performance are described, and planning is emphasized as a method of avoiding noise problems.…

  7. Combined Algorithm for Broadband Active Noise Control%一种复合式宽带有源噪声控制算法

    Institute of Scientific and Technical Information of China (English)

    张瑞华; 谢智波; 张秀丽

    2011-01-01

    A combined algorithm for broadband active noise control is proposed to achieve a high noise control effect. Two algorithms, namely the filtered-X LMS algorithm and the DFT-frequency sampling filter (DFT-FSF) based algorithm are combined together to form the proposed algorithm. The algorithm enables wide band and narrow band noise controls simultaneously. It can achieve the control effect up to 45 dB for sine wave noise and the average control effect up to 15 dB for band limited white noise. The performance of the algorithm is demonstrated by simulation results.%为获得更高的宽带噪声控制效果,提出了一种复合结构有源噪声控制算法.该算法将传统FXLMS算法和DFT-FSF算法并行运行,实现对宽带和窄带噪声的同时降噪.新的复合式算法对正弦波噪声实现高达45dB的降噪,而对带限白噪声的平均降噪量则达到15dB.仿真结果证明了算法的有效性.

  8. Active control of time-varying broadband noise using online system identification with parallel fast-array recursive least squares filters

    NARCIS (Netherlands)

    Berkhoff, Arthur P.; Meijer, H.J.; van Ophem, S.; Sas, P

    2016-01-01

    For broadband active noise control applications with rapidly changing transfer paths, it is desirable to find algorithms with rapid convergence, fast tracking performance, and low computational cost. Recently, a numerically stable algorithm has been presented: a convex mixing fast-array RLS filter.

  9. Genetic noise control via protein oligomerization

    Energy Technology Data Exchange (ETDEWEB)

    Ghim, C; Almaas, E

    2008-06-12

    Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamical role of protein-protein associations. We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch), integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast protein binding-unbinding kinetics, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its intrinsic switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced) state from randomly being induced (uninduced). The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of phenotypically important toggle switches, and nested positive feedback loops in

  10. Holistic control of ship noise emissions

    OpenAIRE

    Borelli Davide; Gaggero Tomaso; Rizzuto Enrico; Schenone Corrado

    2016-01-01

    The sustainability of anthropogenic activities at sea is recently gaining more and more attention. As regards shipping, emissions from ships into the environment of various nature (engine exhaust gases, anti-fouling paints leaching, ballast exchange, releases at sea of oil and other noxious liquid or solid cargoes, of sewage and of garbage) have been recognized as sources of pollution and therefore controlled and limited since a long time. The subject of noise emission...

  11. 主动噪声控制技术在工业换风扇降噪中的应用%Application of Active Noise Control Technique in Noise Reduction System of Industrial Exhaust Fan

    Institute of Scientific and Technical Information of China (English)

    吴亚锋; 姜节胜; 张森社

    2001-01-01

    The noise of exhaust fan is mainly consisted of pass frequency & low second harmonic frequency when blade is rotating. Noises on discrete frequency can be efficiently controled by using active noise control technique. A self control system which has 4 error input & 2 counteracting output is designed by the author. The satisfied result is obtained by using it on noise control system of exhaust fan.%指出了换风扇噪声主要是由风叶旋转时的通频及其低次谐频成分构成,应用主动噪声控制技术能够有效地抑制这些离散频率上的声音。笔者设计了一具有4个误差输入和两个抵消输出的自适应控制系统,并应用于换风扇噪声控制上,获得了满意的实验结果。

  12. Experimental Study for Active Control of a Diesel Exhaus t Noise%柴油机排气噪声有源控制的试验研究

    Institute of Scientific and Technical Information of China (English)

    郭文勇; 黄映云; 朴甲哲

    2001-01-01

    Adaptive active noise control technique has been used to attenuate the low-fr equency exhaust noise of a diesel (4-85) and certain attenuation has been achie ve d in this thesis.Firstly,frequency characteristics of exhaust noise of diesel (4 - 85) are analyzed,thus,the possibility of using active noise control technique on such low-frequency exhaust noise is offered.Secondly,three main difficulties o f hampering the usage of active noise control technique are discussed and the ways to solve are also found out.Then,the design and manufacture of a set of seconda ry source are finished.The coherence of exhaust noise signals and vibration sign als of different points on exhaust duct are analyzed,so,the reference input sign als is chosen.The adaptive active noise control technique which is put forward h as been expounded,and it supplies the experimental basis on which a system model is built and computer program is programmed.Finally,the experiment result has b een recorded and analyzed at last,a sum-up work has been done.%尝试利用自适应有源 噪声控制技术对4-85柴油机低频噪声进行空间消声,取得了一定的消声效果。首先对4-85 柴油 机排气噪声频谱进行了分析,然后提出了针对此低频排气噪声应用有源噪声控制技术的可能 性。其次讨论了妨碍应用有源噪声控制技术的三大困难,并找出了解决方法。引入次级声场 的理论推导并完成了引入次级声场装置的设计、制造。通过对排气噪声信号与排气管上不同 位置振动信号的相干性分析,选取参考输入信号,提出了采用自适应有源噪声控制技术,为 试验提出了依据,对系统进行了建模并编程,对试验结果进行了记录并分析。

  13. Research on active control of vibration and noise for carriage panel%车厢壁板振动噪声主动控制技术研究

    Institute of Scientific and Technical Information of China (English)

    曹友强; 邓兆祥; 廖一橙

    2013-01-01

    Taking the scale model of a car body as the object, the study tried to realize the active control of the vibration and noise in carriage panel by using a new vibration reduction technique, named the piezoelectric smart constrained layer damping ( SCLD). An experimental system for active control the vibration and noise of SCLD body structures was built based on hardware in loop. Using the adaptive technology, a model for active control of the vibration and noise for carriage panel was designed. And taking the carriage inner noise as the control target, the experiment on active control of the vibration and noise for carriage panel was carried out under different outside disturbances . The results showed that the carriage inner noise was decreased obviously by the SCLD technology for vibration reduction under the disturbances of single frequency and complex periodic signal, and the biggest noise reduction was 7. 6dB( A). The study provides the technological basis for improvement of car body NVH performance by using intelligent control strategies.%以某轿车车身结构缩尺物理模型为对象,对利用压电机敏约束层阻尼(SCLD)这一新型阻尼减振技术实现车厢壁板振动噪声的主动控制的方法进行了研究和尝试.搭建了含SCLD结构的车身结构振动噪声主动控制硬件在环实验系统,结合自适应技术设计了车厢壁板主动控制系统模型,并以车厢内部噪声为控制目标,开展了在不同外扰激励下车身壁板振动噪声主动控制实验研究.结果表明,对于单频信号和复杂周期信号激励环境,采用SCLD减振技术都能取得车厢内噪声明显降低的控制效果,且最大降噪量达到了7.6dB(A).这为采用智能控制策略改善车身NVH性能提供了有力的技术基础.

  14. Noise and vibration reduction of diesel engine vehicle making use of the active control engine mount (ACM) system; Active control engine mount (ACM) wo mochiitaa diesel engine tosaisha no seishukusei kojo

    Energy Technology Data Exchange (ETDEWEB)

    MShikata, T.; Aihara, T.; Hyodo, Y.; Aoki, K.; Hirade, T.; Kawazoe, H.; Sato, S.; Kimuraa, T.; Yonekura, K. [Nissan Motor Co. Ltd., Tokyo (Japan)

    1999-02-01

    The active control engine mount (ACM), adopted on `Presage` matched the newly developed direct-injection diesel engine called `NEO-Di YD25DDTi`, can reduce transmitted force to a body structure to almost zero in a wide variety of driving conditions by making use of an adaptive control method with synchronizes the filtered-X algorithm. The ACM system made great improvements in noise and vibration performance, so that fuel consumption, and quietness thanks to the ACM system. (author)

  15. Controlling neuronal noise using chaos control

    CERN Document Server

    Christini, D J; Christini, David J; Collins, James J

    1995-01-01

    Chaos control techniques have been applied to a wide variety of experimental systems, including magneto-elastic ribbons, lasers, chemical reactions, arrhythmic cardiac tissue, and spontaneously bursting neuronal networks. An underlying assumption in all of these studies is that the system being controlled is chaotic. However, the identification of chaos in experimental systems, particularly physiological systems, is a difficult and often misleading task. Here we demonstrate that the chaos criteria used in a recent study can falsely classify a noise-driven, non-chaotic neuronal model as being chaotic. We apply chaos control, periodic pacing, and anticontrol to the non-chaotic model and obtain results which are similar to those reported for apparently chaotic, {\\em in vitro} neuronal networks. We also obtain similar results when we apply chaos control to a simple stochastic system. These novel findings challenge the claim that the aforementioned neuronal networks were chaotic and suggest that chaos control tech...

  16. RBF网络在有源降噪系统中的应用仿真%The Application Simulation of RBF Neural Network in Active Noise Control System

    Institute of Scientific and Technical Information of China (English)

    姜丽飞

    2011-01-01

    针对车辆舱室内的噪声特点,在分析噪声系统非线性特性的基础上,将高速实时信号处理器DSP应用于有源降噪系统的硬件设计中,提出一种基于变结构RBF神经网络的噪声自适应控制方案,给出滤波-x算法并进行仿真验证.同时将该滤波算法的降噪效果和基本的滤波-x算法的进行比较.结果表明,采用该控制算法取得了良好的降噪效果.%Aiming at the characteristics of noise in vehicle cabins, and analyzing nonlinear characteristics of the system, the high-speed real-time signal processor (DSP) was used in active noise control system and an adaptive noise control project based on RBF networks was proposed.An algorithm of FX-RBF was given and simulated.Its noise reduction effect was compared with that of the basic filter-X algorithm.Simulation results showed that the noise reduction effect of the FX-RBF algorithm is good.

  17. 螺桨飞机舱内噪声的主动控制%Active control of propeller induced aircraft cabin noise

    Institute of Scientific and Technical Information of China (English)

    吴亚锋; 任辉; 李江红

    2001-01-01

    文章讨论主动噪声控制技术在螺桨飞机舱内降噪中的应用。一实用的多通道自适应控制系统被开发,并被应用于国产运七螺桨飞机的舱内噪声控制,取得了满意的降噪效果。%An experiment using active control technique to attenuate propeller aircraft cabin noise is presented in this paper. A multichannel adaptive active noise control (ANC) system is developed. A control experiment is fulfilled in chinese Y7 arcraft and satisfiedresults is obtained.

  18. 发动机排气噪声有源控制的模拟实验%A SimulatJion Investigation into Active Noise Control for Exhaust Noise of Engine

    Institute of Scientific and Technical Information of China (English)

    张今朝; 张今阳

    2005-01-01

    发动机排气噪声是宽带噪声.在能够获得参考信号的前提下,采用自适应有源消声(Adaptive active noise control,简称AANC)的前馈控制(Active feedforward control)是有效的方法.为此,在引用Filtered-MS算法的基础上,分别对参考信号的采集和系统识别进行分析,并进行了仿真实验.

  19. Multi-channel FURLS algorithm for active noise control and simulation%多通道FURLS噪声主动控制算法及仿真

    Institute of Scientific and Technical Information of China (English)

    浦玉学; 张方

    2012-01-01

    In order to improve the slow convergence speed shortcomings of LMS algorithm in active broadband noise control in space and eliminate the influence of sound feedback to the stability of the system, this paper combined RLS algorithm with adaptive filter U structure,put forward the Multichannel Filtering-URLS (MFURLS) algorithm and offered a detailed process of this algorithm. This paper designed a basic multi channel noise control system,and made control simulation with fixed frequency noise and broadband noise,comparing with the multi-channel filtering-ULMS (MFULMS) algorithm. The result shows that the MFURLS algorithm system has about 30 dB noise reduction, and the convergence speed is better than the FULMS algorithm. It proves the MFULMS algorithm has great advantage in broadband noise control.%为了改善最小均方(LMS)类算法在空间宽带噪声主动控制问题中收敛速度慢的缺点,消除声反馈对系统稳定性的影响.将快速收敛的最小二乘(RLS)类算法与自适应滤波U形结构结合,提出多通道滤波-URLS(MFURLS)算法,理论上推导该算法详细流程.本文对定频和宽带噪声进行了降噪仿真,将MFURLS算法与多通道滤波-ULMS(MFULMS)算法进行对比,仿真结果表明采用MFURLS算法的系统有30dB左右的降噪量,且收敛速度优于FULMS算法,证明该算法在宽带噪声控制方面具有很大优势.

  20. A Noise-Insensitive Semi-Active Air Suspension for Heavy-Duty Vehicles with an Integrated Fuzzy-Wheelbase Preview Control

    Directory of Open Access Journals (Sweden)

    Zhengchao Xie

    2013-01-01

    Full Text Available Semi-active air suspension is increasingly used on heavy-duty vehicles due to its capabilities of consuming less power and low cost and providing better ride quality. In this study, a new low cost but effective approach, fuzzy-wheelbase preview controller with wavelet denoising filter (FPW, is developed for semi-active air suspension system. A semi-active suspension system with a rolling lobe air spring is firstly modeled and a novel front axle vertical acceleration-based road prediction model is constructed. By adopting a sensor on the front axle, the road prediction model can predict more reliable road information for the rear wheel. After filtering useless signal noise, the proposed FPW can generate a noise-insensitive control damping force. Simulation results show that the ride quality, the road holding, the handling capability, the road friendliness, and the comprehensive performance of the semi-active air suspension with FPW outperform those with the traditional active suspension with PID-wheelbase preview controller (APP. It can also be seen that, with the addition of the wavelet filter, the impact of sensor noise on the suspension performance can be minimized.

  1. The Shortest Distance of Monopole Noise Sources in Plat Space under Active Noise Control%单极子声源平面空间有源降噪的最短距离

    Institute of Scientific and Technical Information of China (English)

    姚加飞; 郭爽

    2014-01-01

    以单极子噪声源与单极子抗噪声源组成的声场为研究对象,得出用单极子抗噪声源控制单极子噪声源,使两声源所在的平面空间内的总声功率最小时两声源本身的声强的关系。并计算空间内任意一点的径向平均有功声强。得出最小径向平均有功声强与声源的频率和两声源的距离有关,在一定频率下,两声源距离越近,控制后的径向平均有功声强越小,距离一定的情况下,频率越小,径向平均有功声强越小。通过仿真实验进行验证,并最终得到某些低频噪声达到全空间消声时噪声源与抗噪声源的最短距离。%This article studies the sound fields of the monopole noise source and monopole anti-noise source. The relationship between the sound intensity of the noise source and the sound intensity of the anti-noise source under the condition of the least sound power in the plat sound field is obtained. In addition, the radial average active sound intensity at any point in the sound field is calculated, which is found to be related to the frequency of the sound source and the distance between the two sources. For a fixed frequency, the radial average active sound intensity decreases with the distance between the two sources increasing after the control. For the fixed distance between the two sources, the radial average active sound intensity decreases with the frequency decreasing after the control. Through the MATLAB simulation, the shortest distance between the noise source and anti-noise source when the sound intensities of some low-frequency noises in the whole space vanish is obtained.

  2. A noise-controlled dynamic bifurcation

    CERN Document Server

    Lythe, G D

    1997-01-01

    We consider a slow passage through a point of loss of stability. If the passage is sufficiently slow, the dynamics are controlled by additive random disturbances, even if they are extremely small. We derive expressions for the `exit value' distribution when the parameter is explicitly a function of time and the dynamics are controlled by additive Gaussian noise. We derive a new expression for the small correction introduced if the noise is coloured (exponentially correlated). There is good agreement with results obtained from simulation of sample paths of the appropriate stochastic differential equations. Multiplicative noise does not produce noise-controlled dynamics in this fashion.

  3. Noise suppression by quantum control before and after the noise

    Science.gov (United States)

    Wakamura, Hiroaki; Kawakubo, Ryûitirô; Koike, Tatsuhiko

    2017-02-01

    We discuss the possibility of protecting the state of a quantum system that goes through noise by measurements and operations before and after the noise process. The aim is to seek the optimal protocol that makes the input and output states as close as possible and to clarify the role of the measurements therein. We consider two cases: one can perform quantum measurements and operations (i) only after the noise process and (ii) both before and after. We prove in a two-dimensional Hilbert space that, in case (i), the noise suppression is essentially impossible for all types of noise and, in case (ii), the optimal protocol for the depolarizing noise is either the "do nothing" protocol or the "discriminate and reprepare" protocol. These protocols are not "truly quantum" and can be considered as classical. They involve no measurement or only use the measurement outcomes. These results describe the fundamental limitations in quantum mechanics from the viewpoint of control theory. Finally, we conjecture that a statement similar to case (ii) holds for higher-dimensional Hilbert spaces and present some numerical evidence.

  4. 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.

  5. Discrete tone noise on two-dimensional wing. Active control for discrete tone; Nijigen seishiyoku kara hasseisuru risan shuhasu soon no kenkyu. Risan shuhasu soon no nodo seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, S. [Mitsubishi Electric Corp., Tokyo (Japan); Akishita, S. [Ritsumeikan University, Kyoto (Japan). Faculty of Science and Engineering

    1996-01-25

    The active noise control of discrete tones generated in a uniform jet flow on a two-dimensional wing was investigated. Discrete tone noise is generated by a self-excited feedback loop formed by the acoustic field and the unstable boundary layer. In this work, we conducted an active control experiment using a flap driven by piezoceramic levers, which can vibrate with a phase delayed from the velocity fluctuation signal on the suction side. When the flap motion lags the pressure fluctuation at the trailing edge with a phase angle of 180 degrees, it was found that the discrete tone noise was reduced by a maximum of about 7 dB, the flow fluctuation intensities in the boundary layer on the suction side were reduced by about half, and the correlation area of the flow fluctuation at the trailing edge decreased. This confirms that discrete tone generation is caused by the feedback loop and that the discrete tone generation is actively reduced by trailing edge control. 10 refs., 14 figs.

  6. Active noise control system based on EMD and loudness%基于EMD与响度的有源噪声控制系统

    Institute of Scientific and Technical Information of China (English)

    聂永红; 程军圣; 张亢; 陈建国

    2012-01-01

    In order to improve the noise reduction effect of the control system, an active noise control system based on EMD(empirical mode decomposition) and loudness is proposed. The noise source is decomposed adaptively using EMD at first and the loudness of all IMFs is calculated in such a system. Then a shaping filter of the error signal is designed according to the amplitudes of the IMF loudness. The filter designed with this method can restrain the components of noise source with small loudness better than A-weighting shaping filter. The noise reduction effect of the active noise control system is simulated. The results show that the control system proposed in this paper can improve the noise reduction effect compared with the system based on filtered-X LMS (filtered-X least mean square) and A-weighting shaping filter.%为了提高有源噪声控制系统的降噪效果,提出了基于经验模态分解( empirical mode decomposition,EMD)和响度的控制系统.该系统首先采用EMD方法对噪声源进行自适应分解,并对分解后的各个固有模态函数(intrinsic mode function,IMF)分量的响度进行计算,然后根据各个分量的响度大小进行残差滤波器的设计.与基于A计权曲线设计的残差滤波器相比,该方法所设计滤波器能更好地抑制响度较小的信号频率成分.对有源噪声控制系统的降噪效果进行了仿真,结果表明,所提出的控制系统比传统滤波-X LMS(filtered-X least mean square)方法和采用基于A计权残差滤波器的系统降噪效果更好.

  7. Helicopter internal noise control: Three case histories

    Science.gov (United States)

    Edwards, B. D.; Cox, C. R.

    1978-01-01

    Case histories are described in which measurable improvements in the cabin noise environments of the Bell 214B, 206B, and 222 were realized. These case histories trace the noise control efforts followed in each vehicle. Among the design approaches considered, the addition of a fluid pulsation damper in a hydraulic system and the installation of elastomeric engine mounts are highlighted. It is concluded that substantial weight savings result when the major interior noise sources are controlled by design, both in altering the noise producing mechanism and interrupting the sound transmission paths.

  8. Control of noise - systems for compact HVAC units

    DEFF Research Database (Denmark)

    Pedersen, Steffen; Møller, Henrik

    2012-01-01

    This paper discusses noise control systems for implementation in compact HVAC units. The control of low-frequency noise presents different problems than at higher frequencies. This is mainly related to the long wavelength, which means that passive solutions require a significant volume of space......, often not available in compact HVAC units. Active control can provide attenuation over a significant frequency range, including low frequencies, while requiring a more limited space. While the concept of active noise control is simple, a number of limitations in the acoustical, electrical and control...... systems affect the performance of implementations. The source pressure and the impedance of a centrifugal fan were measured, and a number of configurations for noise control were investigated. The performance of a simple analogue feedback control was tested in a physical prototype. An adaptive digital...

  9. Analysis and control of computer cooling fan noise

    Science.gov (United States)

    Wong, Kam

    This thesis is divided into three parts: the study of the source mechanisms and their separation, passive noise control, and active noise control. The mechanisms of noise radiated by a typical computer cooling fan is investigated both theoretically and experimentally focusing on the dominant rotor-stator interaction. The unsteady force generated by the aerodynamic interaction between the rotor blades and struts is phase locked with the blade rotation and radiates tonal noise. Experimentally, synchronous averaging with the rotation signal extracts the tones made by the deterministic part of the rotor-strut interaction mechanism. This averaged signal is called the rotary noise. The difference between the overall noise and rotary noise is defined as random noise which is broadband in the spectrum. The deterministic tonal peaks are certainly more annoying than the broadband, so the suppression of the tones is the focus of this study. Based on the theoretical study of point force formulation, methods are devised to separate the noise radiated by the two components of drag and thrust forces on blades and struts. The source separation is also extended to the leading and higher order modes of the spinning pressure pattern. By using the original fan rotor and installing it in various casings, the noise sources of the original fan are decomposed into elementary sources through directivity measurements. Details of the acoustical directivity for the original fan and its various modifications are interpreted. For the sample fan, two common features account for most of the tonal noise radiated. The two features are the inlet flow distortion caused by the square fan casing, and the large strut carrying the electric wires for the motor. When the inlet bellmouth is installed and the large strut is trimmed down to size, a significant reduction of 12 dB in tonal sound power is achieved. These structural corrections constitute the passive noise control. However, the end product still

  10. Noise and vibration reduction of diesel engine vehicle making use of the active control engine mount (ACM) system; Active control engine mount (ACM) wo mochiita diesel engine tosaisha no seishukusei kojo

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, K.; Hirade, T.; Hyodo, Y.; Aihara, T.; Shikata, T. [Nissan Motor Co. Ltd., Tokyo (Japan)

    1998-05-01

    An active control engine mount (ACM) system is described, which aims at reducing noise and vibration of diesel engine vehicles. ACM systems are arranged on the front and rear mounts, and reduce the noise by lowering the spring constant. The main body of an ACM system is a hydraulic mount, and is provided with a hydraulic pressure amplifier that makes use of liquid resonance, an electromagnetic actuator that converts hydraulic pressure into force, and a load sensor that detects the force that is transmitted to the vehicle body. The controller of an ACM control system feeds electric currents as needed to an actuator so as to keep the transmission of force to the minimum so that load sensor signals will be zero. The actuator employed in this report can augment the force generated there. All the parameters for the calculation model are optimized so that controllable input amplitude will increase. In the diesel engine vehicle into which ACM systems are incorporated, vibration during the idling operation is damped by approximately 10dB, the resultant vibration level as low as that of a gasoline engine vehicle. Harmonic components are also lowered in addition the second-order component. The same is true for the booming noise that is generated by a vehicle that is running, which is again damped by approximately 10dB. 2 refs., 14 figs.

  11. 基于遗传算法的有源消声系统设计%Design of active noise control system based on genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    江华丽

    2012-01-01

    It is introduced the adaptive active noise control model based on genetic algorithm, introduces the principle of active noise control system, the adaptive control system lies in its control algorithm to adjust the filter coefficients. The main factors must be considered in the muffler system error, the sound delay, sound attenuation, and the formula by adding the phase change. The system combines neural networks to improve the precision and accuracy, can be used to optimize the structure of the neural network weights. Experiment proves that adaptive active noise control system based on neural network algorithm has a good effect,the system is stable.%建立了基于遗传算法的自适应有源消声模型,介绍有源消声系统原理,自适应控制系统的关键在于其控制算法,用算法来调整滤波器的系数.在消声系统里必须考虑的因素主要有误差、声音的延迟、声音的衰减、在公式中适当的加入相位变化等.该系统结合神经网络算法,遗传算法和BP算法结合并改进提高了精度和准确性,可以用来优化神经网络的结构及其权值.实验分别从单音和复音情况进行,实验结果证明了基于神经网络算法的自适应有源消声系统有良好的消声效果,该系统稳定性较强.

  12. A before-after control-impact assessment to understand the potential impacts of highway construction noise and activity on an endangered songbird.

    Science.gov (United States)

    Long, Ashley M; Colón, Melanie R; Bosman, Jessica L; Robinson, Dianne H; Pruett, Hannah L; McFarland, Tiffany M; Mathewson, Heather A; Szewczak, Joseph M; Newnam, J Cal; Morrison, Michael L

    2017-01-01

    Anthropogenic noise associated with highway construction and operation can have individual- and population-level consequences for wildlife (e.g., reduced densities, decreased reproductive success, behavioral changes). We used a before-after control-impact study design to examine the potential impacts of highway construction and traffic noise on endangered golden-cheeked warblers (Setophaga chrysoparia; hereafter warbler) in urban Texas. We mapped and monitored warbler territories before (2009-2011), during (2012-2013), and after (2014) highway construction at three study sites: a treatment site exposed to highway construction and traffic noise, a control site exposed only to traffic noise, and a second control site exposed to neither highway construction or traffic noise. We measured noise levels at varying distances from the highway at sites exposed to construction and traffic noise. We examined how highway construction and traffic noise influenced warbler territory density, territory placement, productivity, and song characteristics. In addition, we conducted a playback experiment within study sites to evaluate acute behavioral responses to highway construction noises. Noise decreased with increasing distance from the highways. However, noise did not differ between the construction and traffic noise sites or across time. Warbler territory density increased over time at all study sites, and we found no differences in warbler territory placement, productivity, behavior, or song characteristics that we can attribute to highway construction or traffic noise. As such, we found no evidence to suggest that highway construction or traffic noise had a negative effect on warblers during our study. Because human population growth will require recurring improvements to transportation infrastructure, understanding wildlife responses to anthropogenic noise associated with the construction and operation of roads is essential for effective management and recovery of prioritized

  13. Genetic noise control via protein oligomerization

    Directory of Open Access Journals (Sweden)

    Almaas Eivind

    2008-11-01

    Full Text Available Abstract Background Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamic role of protein-protein interactions. Results We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch, integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast binding-unbinding kinetics among proteins, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its random switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced state from randomly being induced (uninduced. Conclusion The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of regulatory circuits

  14. Multi-wave active noise control system at the underground mine%矿用多波主动噪声控制系统

    Institute of Scientific and Technical Information of China (English)

    田子建; 张立亚

    2011-01-01

    为降低矿井噪声污染,提出了一个基于改进FXLMS算法的矿用多波主动噪声控制方案.针对矿井巷道较长,噪声源、次级声源间距离较远的特点,多波设计方案可以有效解决单波麦克风失匹配等带来的误差,改进FXLMS算法的矿用多波主动噪声控制方案使修正的误差信号趋于零,该设计方案能提高自适应滤波器的次级声路径权系数更新变化速度,减小权系数的变化对系统的影响,提高系统的收敛速度.采用Matlab对设计方案进行模拟仿真,仿真结果表明:设计方案的输入和扬声器输出基本上是频率、振幅相等,相位相反的信号,提出的设计方案将能有效地消除矿井三维空间内的噪声.%To reduce the noise pollution in the coal mine,presented a mining multi-wave active noise control scheme based on the improved FXLMS algorithm. For long roadway in coal mines and the far distances between the main and secondary noise sources, the multi-wave scheme can effectively solve the problems of the single microphone' s mis-matching errors. The multi-wave active noise control scheme based on the improved FXLMS algorithm can even narrow down the modified error signals to zero. This scheme can increase the refreshing rate of the weight coefficients of the adaptive filters' secondary noise path. Moreover,it can reduce the effects of the changing of weight coefficients on the system. And then it can increase the system convergence speed. The scheme is simulated by Matlab. The results illus-trated that the scheme' s input and the speaker' s output are basically the signals of the same frequency, the same am-plitude, and the inverse phrase. And the scheme is proved can effectively eliminate the noises in the 3-dimention space of the coal mine.

  15. 在线参数辨识的脉冲噪声有源控制%Active Control of Impulsive Noise Based on On-line Parameter Identification

    Institute of Scientific and Technical Information of China (English)

    杨琴; 周亚丽; 张奇志

    2013-01-01

    Active noise control is a kind of active control methods and has been widely used to attenuate the noise which yields Gaussian distribution. But for most of non-Gaussian impulsive noises, the traditional adaptive algorithms are not appropriate for controlling the impulsive noise. The main reason is that there is no finite second-order moment for the impulsive noise. In this paper, two kinds of on-line parameter identification algorithms based on the classical Filter-x LMS algorithm were presented which are appropriate for non-Gaussian impulsive noise. One is FxLMPest and FxLMADadapt algorithms based on on-line parameters identification to estimate characteristics exponent of impulsive noise with an SαS distribution, and the other is BDP algorithm based on SKM and AM algorithms presented by Sun et al, which uses a simple on-line recursive procedure to estimate amplitude thresholds. Both methods do not need prior information of characteristics exponent and amplitude thresholds of impulsive noise. And the simulation results also show that the two methods can effectively suppress the impulsive noise, and its robust performance is significantly better than Filter-x LMS algorithm.%  有源噪声控制是一种主动控制方法,目前已广泛应用于对高斯分布噪声进行衰减。但是传统的用于控制噪声的自适应算法不再适用大多数服从非高斯分布的脉冲噪声,主要原因是这种脉冲噪声没有有限的二阶统计量。在经典的Filter-x LMS算法的基础上提出两种适用于服从非高斯分布尖峰脉冲噪声情况下的在线参数辨识方法,一种是利用在线参数辨识方法对服从SαS稳定分布的脉冲噪声进行特征指数的估计,进而实现降噪目的的FxLMPest和FxLMADadapt算法;另一种是在Sun等人提出的SKM和AM算法基础上利用在线递归过程实现对幅度阈值估计的BDP算法。这两种算法均不需要获得脉冲噪声的特征指数和阈值的

  16. Noise and vibration control in aircraft: A global approach

    Science.gov (United States)

    Berhault, J.-P.; Venet, G.; Fontenot, J.

    This paper proposes an approach to noise and vibration control in new and existing aircraft, employing a global approach; that is, considering all source and effects in development of the control plan. The approach employs acoustic imaging of the engines and the cabin internal space and a vibration analysis model to describe the entire system. Completion of the global analysis leads to the treatment plan, which may include various passive mounts tecnologies and/or an active noise system.

  17. Numerical investigation of tandem-cylinder aerodynamic noise and its control with application to airframe noise

    Science.gov (United States)

    Eltaweel, Ahmed

    Prediction and reduction of airframe noise are critically important to the development of quieter civil transport aircraft. The key to noise reduction is a full understanding of the underlying noise source mechanisms. In this study, tandem cylinders in cross-flow as an idealization of a complex aircraft landing gear configuration are considered to investigate the noise generation and its reduction by flow control using single dielectric barrier discharge plasma actuators. The flow over tandem cylinders at ReD = 22, 000 with and without plasma actuation is computed using large-eddy simulation. The plasma effect is modeled as a body force obtained from a semi-empirical model. The flow statistics and surface pressure frequency spectra show excellent agreement with previous experimental measurements. For acoustic calculations, a boundary-element method is implemented to solve the convected Lighthill equation. The solution method is validated in a number of benchmark problems including flows over a cylinder, a rod-airfoil configuration, and a sphere. With validated flow field and acoustic solver, acoustic analysis is performed for the tandem-cylinder configuration to extend the experimental results and understand the mechanisms of noise generation and its control. Without flow control, the acoustic field is dominated by the interaction between the downstream cylinder and the upstream wake. Through suppression of vortex shedding from the upstream cylinder, the interaction noise is reduced drastically by the plasma flow control, and the vortex-shedding noise from the downstream cylinder becomes equally important. At a free-stream Mach number of 0.2, the peak sound pressure level is reduced by approximately 16 dB. This suggests the viability of plasma actuation for active control of airframe noise. The numerical investigation is extended to the noise from a realistic landing gear experimental model. Coarse-mesh computations are performed, and preliminary results are

  18. Arc-tangent Transformation Algorithm for Active Impulsive Noise Control%有源脉冲噪声控制的反正切变换算法

    Institute of Scientific and Technical Information of China (English)

    邵俊; 周亚丽; 张奇志

    2012-01-01

    In recent years, some effective algorithms for active impulsive noise control have been proposed. But these algorithms may not be stable due to the high-and-sharp peaks of the impulsive noise. To overcome the shortage of these algorithms, a new algorithm based on minimizing the squared arc-tangent transformation of the error signal was proposed. This algorithm doesn' t need to consider thresholds estimation and parameters selection based on priori knowledge of impulsive noise. Moreover, the algorithm is simple in structure, and easy to be realized. The simulation results show that the proposed algorithm can effectively eliminate the impulsive noise, and compared with the other algorithms, the performance of the proposed algorithm has a better convergence and stability.%近年来,针对有源脉冲噪声控制,提出一些较为有效的算法.由于脉冲噪声的高尖峰特性,给算法带来了不稳定.为克服这些算法的不足,提出一种基于反正切变换的滤波x最小均方差算法.该算法不需要根据脉冲噪声的先验知识估测阈值和选择参数,并且算法结构简单、易于实现.仿真结果表明该算法能有效地消除脉冲噪声,与其他几种算法相比表现了更好的收敛性和稳定性.

  19. Active Noise Control Using Fuzzy Neural Network%模糊神经网络在有源降噪中的仿真研究

    Institute of Scientific and Technical Information of China (English)

    姜丽飞; 李传光

    2003-01-01

    @@ 1引言 众所周知,噪声污染已成为一个世界性的问题.多年来,人们在不断探索控制噪声的有效方法.[1]传统的无源噪声控制(用吸声材料吸声、阻尼处理等)在高频段取得了较好的消声效果,但在低频段消声效果不理想;而有源噪声控制技术(Active Noise Control ANC)以其独特的优点为低频噪声控制开辟了一条崭新的途径.由于噪声是时变的,为了达到对噪声的实时控制,自适应有源降噪控制技术(Adaptive Active Noise Control AANC)应运而生,并伴随着声学理论、控制理论和电子技术的发展,高速信号处理器DSP的开发成功而蓬勃发展起来.原理示意图如图1所示.

  20. Model independent control of lightly damped noise/vibration systems.

    Science.gov (United States)

    Yuan, Jing

    2008-07-01

    Feedforward control is a popular strategy of active noise/vibration control. In well-damped noise/vibration systems, path transfer functions from actuators to sensors can be modeled by finite impulse response (FIR) filters with negligible errors. It is possible to implement noninvasive model independent feedforward control by a recently proposed method called orthogonal adaptation. In lightly damped noise/vibration systems, however, path transfer functions have infinite impulse responses (IIRs) that cause difficulties in design and implementation of broadband feedforward controllers. A major source of difficulties is model error if IIR path transfer functions are approximated by FIR filters. In general, active control performance deteriorates as model error increases. In this study, a new method is proposed to design and implement model independent feedforward controllers for broadband in lightly damped noise/vibration systems. It is shown analytically that the proposed method is able to drive the convergence of a noninvasive model independent feedforward controller to improve broadband control in lightly damped noise/vibration systems. The controller is optimized in the minimum H2 norm sense. Experiment results are presented to verify the analytical results.

  1. 空间双通道电机噪声有源控制系统研究%Dual-channel Space Active Noise Control System for Motor Operating Noise

    Institute of Scientific and Technical Information of China (English)

    刘会灯; 邱阿瑞

    2011-01-01

    A dual-channel space active noise control (ANC) system was invesitaged to control opetating noise by a combined motors with a DC motor and an inducation motor. The experiments were conducted with four dual-channel ANC algorithms including Filter-x Least Mean Square (FxLMS) , Filter-u Recursive Least Mean Square (FuRLMS) , Hybrid FxLMS (HFxLMS) and Feedback FxLMS (FBFxLMS) to control the motor operating noise, and the results show that the average sound pressure level(SPL) reductions on the horizontal and vertical planes of the noise quiet zone are larger than 10dB when the DC motor operates at the speeds of 1300r/min, 1400r/min and 1500r/min. The maximum SPL reductions on the horizontal plane are 17. 92dB, 13. 28dB and 17. 88dB, while 16. 73dB, 16. 36dB and 16. 99dB on the vertical plane, respectively. The remarkable SPL reductions in the noise quiet zone show that the proposed dual-channel space ANC system can be effective to control the motor operating noise.%针对实验室一台直流电动机-同步发电机机组运行噪声的频谱特点,提出空间双通道有源噪声控制系统降低电机运行噪声.采用四种双通道控制算法(Ⅰ) FxLMS算法, (Ⅱ)FuRLMS算法, (Ⅲ)HFxLMS算法以及(Ⅳ) FBFxLMS算法进行电机运行噪声有源控制实验,对于电机运行转速分别为1300 r/min、1400 r/min和1500 r/min时,噪声控制区域内水平平面和垂直平面上平均声压级降低量均大于10 dB,水平平面上最大声压级降低量分别为17.92 dB、13.28 dB和17.88 dB,垂直平面上最大声压级降低量分别为16.73 dB、16.36 dB和16.99 dB,降噪效果表明本文提出的空间双通道有源控制系统能有效地降低电机运行噪声.

  2. Controlled exposure to diesel exhaust and traffic noise - Effects on oxidative stress and activation in mononuclear blood cells

    DEFF Research Database (Denmark)

    Hemmingsen, Jette Gjerke; Møller, Peter; Jantzen, Kim

    2015-01-01

    unaltered in peripheral blood mononuclear cells (PBMCs). No significant differences in DNA damage levels, measured by the comet assay, were observed after DE exposure, whereas exposure to high noise levels was associated with significantly increased levels of hOGG1-sensitive sites in PBMCs. Urinary levels...

  3. Noise-control needs in the developing energy technologies

    Energy Technology Data Exchange (ETDEWEB)

    Keast, D.N.

    1978-03-01

    The noise characteristics of existing energy conversion technologies, e.g., from obtaining and processing fossil fuels to power plants operations, and of developing energy technologies (wind, geothermal sources, solar energy or fusion systems) are discussed in terms of the effects of noise on humans, animals, structures, and equipment and methods for noise control. Regulations for noise control are described. Recommendations are made for further research on noise control and noise effects. (LCL)

  4. Active control of flow noise sources in turbulent boundary layer on a flat-plate using piezoelectric bimorph film

    Energy Technology Data Exchange (ETDEWEB)

    Song, Woo Seog; Lee, Seung Bae [Inha University, Incheon (Korea, Republic of); Shin, Dong Shin [Hongik University, Seoul (Korea, Republic of); Na, Yang [Konkuk University, Seoul (Korea, Republic of)

    2006-11-15

    The piezoelectric bimorph film, which, as an actuator, can generate more effective displacement than the usual PVDF film, is used to control the turbulent boundary-layer flow. The change of wall pressures inside the turbulent boundary layer is observed by using the multi-channel microphone array flush-mounted on the surface when actuation at the non-dimensional frequency f{sub b}{sup +} =0.008 and 0.028 is applied to the turbulent boundary layer. The wall pressure characteristics by the actuation to produce local displacement are more dominantly influenced by the size of the actuator module than the actuation frequency. The movement of large-scale turbulent structures to the upper layer is found to be the main mechanism of the reduction in the wall-pressure energy spectrum when the 700{nu}/u{sub {tau}}-long bimorph film is periodically actuated at the non-dimensional frequency f{sub b}{sup +} =0.008 and 0.028. The bimorph actuator is triggered with the time delay for the active forcing at a single frequency when a 1/8' pressure-type, pin-holed microphone sensor detects the large-amplitude pressure event by the turbulent spot. The wall-pressure energy in the late-transitional boundary layer is partially reduced near the convection wavenumber by the open-loop control based on the large amplitude event.

  5. On spatial spillover in feedforward and feedback noise control

    Science.gov (United States)

    Xie, Antai; Bernstein, Dennis

    2017-03-01

    Active feedback noise control for rejecting broadband disturbances must contend with the Bode integral constraint, which implies that suppression over some frequency range gives rise to amplification over another range at the performance microphone. This is called spectral spillover. The present paper deals with spatial spillover, which refers to the amplification of noise at locations where no microphone is located. A spatial spillover function is defined, which is valid for both feedforward and feedback control with scalar and vector control inputs. This function is numerically analyzed and measured experimentally. Obstructions are introduced in the acoustic space to investigate their effect on spatial spillover.

  6. 三类有源噪声控制算法性能比较%Comparison of Performances of Three Types of Active Noise Control Algorithms

    Institute of Scientific and Technical Information of China (English)

    陈珏; 玉昊昕; 陈克安

    2013-01-01

    设计了FxLMS、GSFxAP、FsLMS等三类有源控制算法的仿真实验和消声室实验,分析了算法性能,对算法的适用条件进行深入研究。结果表明:当次级通路为线性通路时,在实际应用对收敛速度要求不高的情况下,选择FxLMS算法的性能代价比最高。如果欲控制的噪声为非平稳噪声或对算法收敛速度要求较高,GSFxAP算法是最优选择。如果参考信号与初级信号相关性差,选用FsLMS算法最为合适。上述结论为实际工程中有源控制算法的选择提供了理论依据。%In order to reasonably choose active noise control (ANC) algorithm in practical engineering, the performances of three typical ANC algorithms, FxLMS, GSFxAP and FsLMS, were investigated in different conditions by simulations and experiments. The conditions of application of the algorithms were also studied. It was concluded that if the secondary path is linear and the convergence speed does not need to be very high, FxLMS algorithm is the best choice;if the noise to be controlled (i.e. the primary noise) is non-stationary or the convergence speed needs to be very high, GSFxAP algorithm is a suitable choice;if the correlation between the primary noise and reference signal is weak, FsLMS algorithm is the reasonable choice. This conclusion provides a theoretical guide for the choice of ANC algorithm in practical engineering.

  7. Noise control considerations for patient rooms

    Science.gov (United States)

    Davenny, Benjamin

    2005-09-01

    The patient room envelope is a path between outside noise sources and the patient receiver. Within the patient room there are several sources including televisions, clinical monitor alarms, medical pumps, etc. Noise control in patient rooms relies on a combination of the sound transmission loss of the patient room envelope and the level of background sound at the patient's head. Guidelines published by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), American Institute of Architects (AIA), and the U.S. Department of Defense for background noise and sound transmission loss in patient rooms will be discussed. Appropriate levels, spectra, and temporal characteristics of background sound at the patient head location may be helpful in raising the threshold of annoying sounds. Various means of personal hearing protection for patients will be discussed. Sound-pressure levels in patient rooms reported in previous literature will also be discussed.

  8. 基于DSP的有源噪声控制系统设计%The Design of Active Noise Control System Based on DSP

    Institute of Scientific and Technical Information of China (English)

    刘姜涛

    2012-01-01

    Active noise control system based on DSP is designed.The paper gives an overall analysis of the structure of the system,and how to select components of the system.Adaptive control algorithm of control system is designed and simulated by CCS3.3.With other parameters of the system fixed,control effect of the system is analyzed by changing the filter order.As can be seen from the experimental effect,good control effect can be obtained when appropriate parameters are selected.%本文设计了基于DSP的有源消声控制系统,对系统的结构进行了整体分析,给出系统部件的选择依据,设计了控制系统的自适应控制算法,并以CCS3.3软件为仿真平台进行仿真实验,将系统中其它参数固定,改变滤波器阶数,分析系统的控制效果。从实验效果中可以看出,在选取恰当的参数时,可以取得较好的控制效果。

  9. Noise Pollution Control System in the Hospital Environment

    Science.gov (United States)

    Figueroa Gallo, LM; Olivera, JM

    2016-04-01

    Problems related to environmental noise are not a new subject, but they became a major issue to solve because of the increasing, in complexity and intensity, of human activities due technological advances. Numerous international studies had dealt with the exposure of critical patients to noisy environment such as the Neonatal Intensive Care Units; their results show that there are difficulties in the organization in the developing brain, it can damage the delicate auditory structures and can cause biorhythm disorders, specially in preterm infants. The objective of this paper is to present the development and implementation of a control system that includes technical-management-training aspects to regulate the levels of specific noise sources in the neonatal hospitalization environment. For this purpose, there were applied different tools like: observations, surveys, procedures, an electronic control device and a training program for a Neonatal Service Unit. As a result, all noise sources were identified -some of them are eliminable-; all the service stable staff categories participated voluntarily; environmental noise measurements yielded values between 62.5 and 64.6 dBA and maximum were between 86.1 and 89.7 dBA; it was designed and installed a noise control device and the staff is being trained in noise reduction best practices.

  10. 49 CFR 227.113 - Noise operational controls.

    Science.gov (United States)

    2010-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION OCCUPATIONAL NOISE EXPOSURE Occupational Noise Exposure for Railroad Operating Employees. § 227.113 Noise operational controls. (a) Railroads may use noise operational controls at any sound level to reduce exposures to levels below those required by Table A-1 of appendix A...

  11. Active control of probability amplitudes in a mesoscale system via feedback-induced suppression of dissipation and noise

    Science.gov (United States)

    Gupta, Chaitanya; Peña Perez, Aldo; Fischer, Sean R.; Weinreich, Stephen B.; Murmann, Boris; Howe, Roger T.

    2016-12-01

    We demonstrate that a three-terminal potentiostat circuit reduces the coupling between an electronic excitation transfer (EET) system and its environment, by applying a low-noise voltage to its electrical terminals. Inter-state interference is preserved in the EET system by attenuating the dissipation in the quantum system arising from coupling to the surrounding thermodynamic bath. A classical equivalent circuit is introduced to model the environment-coupled excitation transfer for a simplified, two-state system. This model provides a qualitative insight into how the electronic feedback affects the transition probabilities and selectively reduces dissipative coupling for one of the participant energy levels EET system. Furthermore, we show that the negative feedback also constrains r.m.s. fluctuations of the energy of environmental vibrational states, resulting in persistent spectral coherence between the decoupled state and vibronic levels of the complementary state. The decoupled vibronic channel therefore can serve as a probe for characterizing the vibronic structure of the complementary channel of the EET system.

  12. Rapidly converging multichannel controllers for broadband noise and vibrations

    NARCIS (Netherlands)

    Berkhoff, A.P.

    2010-01-01

    Applications are given of a preconditioned adaptive algorithm for broadband multichannel active noise control. Based on state-space descriptions of the relevant transfer functions, the algorithm uses the inverse of the minimum-phase part of the secondary path in order to improve the speed of converg

  13. 一台高强化柴油机排气噪声有源控制实验研究%Adaptive Active Exhaust Noise Control of a High Intensity Diese l Engine

    Institute of Scientific and Technical Information of China (English)

    李径定; 方卓毅; 罗永革

    2001-01-01

    Exhaust noise is the main noise source of a dieselengine,especially to a high intensity diesel engine.It worsen work environment of ope rators, and it may lead some disease in long time.An adaptive active noise control syste m is designed to control exhaust noise of a high intensity diesel engine,the experimental results manifest the system is very efficient in controlling the noise ,and it enhances the fuel economy.%柴油机噪声使操作人员工作环境恶化,长期还危害操作人员的身体健康。排气噪声对柴油机整机噪声贡献很大,本文设计了一套自适应有源噪声控制(AdaptiveActive Noise Control)系统用于控制排气噪声,实验结果表明该系统效果良好。

  14. A noise immunity controlled quantum teleportation protocol

    Science.gov (United States)

    Li, Dong-fen; Wang, Rui-jin; Zhang, Feng-li; Baagyere, Edward; Qin, Zhen; Xiong, Hu; Zhan, Huayi

    2016-08-01

    With the advent of the Internet and information and communication technology, quantum teleportation has become an important field in information security and its application areas. This is because quantum teleportation has the ability to attain a timely secret information delivery and offers unconditional security. And as such, the field of quantum teleportation has become a hot research topic in recent years. However, noise has serious effect on the safety of quantum teleportation within the aspects of information fidelity, channel capacity and information transfer. Therefore, the main purpose of this paper is to address these problems of quantum teleportation. Firstly, in order to resist collective noise, we construct a decoherence-free subspace under different noise scenarios to establish a two-dimensional fidelity quantum teleportation models. And also create quantum teleportation of multiple degree of freedom, and these models ensure the accuracy and availability of the exchange of information and in multiple degree of freedom. Secondly, for easy preparation, measurement and implementation, we use super dense coding features to build an entangled quantum secret exchange channel. To improve the channel utilization and capacity, an efficient super dense coding method based on ultra-entanglement exchange is used. Thirdly, continuous variables of the controlled quantum key distribution were designed for quantum teleportation; in addition, we perform Bell-basis measurement under the collective noise and also prepare the storage technology of quantum states to achieve one-bit key by three-photon encoding to improve its security and efficiency. We use these two methods because they conceal information, resist a third party attack and can detect eavesdropping. Our proposed methods, according to the security analysis, are able to solve the problems associated with the quantum teleportation under various noise environments.

  15. A noise immunity controlled quantum teleportation protocol

    Science.gov (United States)

    Li, Dong-fen; Wang, Rui-jin; Zhang, Feng-li; Baagyere, Edward; Qin, Zhen; Xiong, Hu; Zhan, Huayi

    2016-11-01

    With the advent of the Internet and information and communication technology, quantum teleportation has become an important field in information security and its application areas. This is because quantum teleportation has the ability to attain a timely secret information delivery and offers unconditional security. And as such, the field of quantum teleportation has become a hot research topic in recent years. However, noise has serious effect on the safety of quantum teleportation within the aspects of information fidelity, channel capacity and information transfer. Therefore, the main purpose of this paper is to address these problems of quantum teleportation. Firstly, in order to resist collective noise, we construct a decoherence-free subspace under different noise scenarios to establish a two-dimensional fidelity quantum teleportation models. And also create quantum teleportation of multiple degree of freedom, and these models ensure the accuracy and availability of the exchange of information and in multiple degree of freedom. Secondly, for easy preparation, measurement and implementation, we use super dense coding features to build an entangled quantum secret exchange channel. To improve the channel utilization and capacity, an efficient super dense coding method based on ultra-entanglement exchange is used. Thirdly, continuous variables of the controlled quantum key distribution were designed for quantum teleportation; in addition, we perform Bell-basis measurement under the collective noise and also prepare the storage technology of quantum states to achieve one-bit key by three-photon encoding to improve its security and efficiency. We use these two methods because they conceal information, resist a third party attack and can detect eavesdropping. Our proposed methods, according to the security analysis, are able to solve the problems associated with the quantum teleportation under various noise environments.

  16. Research on the application of active sound barriers for the transformer noise abatement

    Directory of Open Access Journals (Sweden)

    Hu Sheng

    2016-01-01

    Full Text Available Sound barriers are a type of measure most commonly used in the noise abatement of transformers. In the noise abatement project of substations, the design of sound barriers is restrained by the portal frames which are used to hold up outgoing lines from the main transformers, which impacts the noise reduction effect. If active sound barriers are utilized in these places, the noise diffraction of sound barriers can be effectively reduced. At a 110kV Substation, an experiment using a 15-channel active sound barrier has been carried out. The result of the experiment shows that the mean noise reduction value (MNRV of the noise measuring points at the substation boundary are 1.5 dB (A. The effect of the active noise control system is impacted by the layout of the active noise control system, the acoustic environment on site and the spectral characteristic of the target area.

  17. 机动车辆室内复合主动噪声控制系统的设计%Design of the Hybrid Active Noise Controlling in the Atuomobile Room

    Institute of Scientific and Technical Information of China (English)

    胡啸; 胡爱群; 涂有超

    2001-01-01

    This paper presents a scheme of reducing noises inside theautomobile room by means of the Hybrid Active Noise Controlling.It bases on the systematic researches on the technology of active noise controlling and the analysis of noise sources inside the automobile room.The proposed scheme can attenuate the total noise radiation from low frequency noises when a feedback controller is used,and can also attenuate the base and harmonic frequencies of the engine noises when a feed-forward controller is used.Analyses indicate that the presented scheme can reduce the automobile room noises effectively.%本文在系统研究主动噪声控制技术和机动车辆内噪声来源的基础上,提出利用复合主动噪声控制思想,改善机动车辆室内噪声环境的方案及其算法实现。具体地说,就是利用反馈主动噪声控制系统,抵消低频噪声对车室内的总噪声辐射;利用前馈主动噪声控制系统,抵消发动机噪声的基频分量及其多次谐波分量。分析表明:该方案具有较好的除噪效果和较高的实用价值。

  18. Distributed Absorber for Noise and Vibration Control

    Directory of Open Access Journals (Sweden)

    Michel Azoulay

    2011-01-01

    Full Text Available An approach to a wide-band frequency passive vibration attenuation is introduced in this paper. This aims to suppress noise and vibration of extended multimode objects like plates, panels and shells. The absorber is arranged in the form of a single-layer assembly of small inertial bodies (balls being distributed and moulded within the light visco-elastic media (e.g. silicone resin. The absorber as a whole is embedded into object face covering the critical patches of the system surface. For the purpose of characterization, the authors introduced the complex frequency response function relating the volume velocity produced by the vibrating object surface (response stimulated by a point-wise force (stimulus applied to a particular point. The simulation and optimization of the main frequency characteristics has been performed using a full scale 3-dimensional Finite Element model. These revealed some new dynamic features of absorber's structures, which can contribute to vibration attenuation. A full-scale physical experimentation with synthesised absorber's structures confirmed the main results of simulation and has shown significant noise reduction over a staggering 0–20 kHz frequency band. This was achieved with a negligible weight and volume penalty due to the addition of the absorber. The results can find multiple applications in noise and vibration control of different structures. Some examples of such applications are presented.

  19. Active noise cancellation in hearing devices

    DEFF Research Database (Denmark)

    2013-01-01

    Disclosed is a hearing device system comprising at least one hearing aid circuitry and at least one active noise cancellation unit, the at least one hearing aid circuitry comprises at least one input transducer adapted to convert a first audio signal to an electric audio signal; a signal processor...... to said generated sound pressure, wherein the hearing device system further comprises a combiner unit adapted to combine the processed electric audio signal with the active noise cancellation signal, to obtain a combined signal and to provide the combined signal to the output transducer....... connected to the at least one input transducer and adapted to process said electric audio signal by at least partially correcting for a hearing loss of a user; an output transducer adapted to generate from at least said processed electric audio signal a sound pressure in an ear canal of the user, whereby...

  20. [Optimally control urban railway noise by sound propagation path].

    Science.gov (United States)

    Di, Guo-qing; Li, Zheng-guang; Chen, Yu; Zhang, Bang-jun

    2008-08-01

    In order to control railway noise pollution in urban areas, the residential district located near the Zhegan railway in Hangzhou urban was taken for example, and some controlling measures were proposed based on the investigation in railway noise impact as well as the planning of the district, the environmental scene and the project devises. The measures included setting man-made soil slopes, noise barriers and virescence. Combining some of them could be a typical noise reduction scheme. The professional software Cadna/A was used to predict the noise reduction results of every scheme. Results show that the maximal difference of noise reduction is 19.4 dB and the noise reduction effect of the second scheme is best. However, if only railway noise influence is considered, the first scheme is best. The research results can provide reference for residential districts planning and noise control near the railway in urban areas.

  1. 管道低频噪声的自适应有源控制%Adaptive Active Control of Low-Frequency Noise in a Duct

    Institute of Scientific and Technical Information of China (English)

    李传光; 李悟; 韩秀苓

    1999-01-01

    目的针对实际的具有行波的管道模型,研究一种降噪方案.方法通过建立数学模型和用来导出降噪的自适应系统的传递函数,对RLS、LMS和LSL算法的效果进行分析和比较.结果不存在声反馈时,对0-500Hz的宽带噪声可达到平均降噪量(MNRV)27.5dB.若存在声反馈并使用气流扬声器时,MNRV只有近似4.9dB.当该扬声器具有平坦特性时,MNRV可提高10.2dB.结论这项抵消技术可用于对排气管降噪.原则上,它亦可用于三维封闭空间的降噪问题.%Aim To study a method realizing noise control for a physical model of progressive wave in a duct. Methods A mathematical model was constructed and a transfer function of the adaptive system for noise control was also worked out; moreover, the effects of some algorithms such as RLS,LMS and LSL on noise control were analyzed and compared. Results Without the feedback of sound, the mean noise reduce value(MNRV) of 27.5 dB for broadband noise from 0 to 500Hz in frequency were achieved. When acoustic feedback took place and an air-stream loudspeaker was used, the MNRV was only about 4.9dB. But if the loudspeaker had a plain frequency feature, MNRV was improved by 10.2dB. Conclusion The technique is applied to ruducing the noise from engines' exhausted gas pipes. It is, in principle, used for noise-cancelling in a closed three dimensional space.

  2. Analysis of noise control measures on outdoor machinery using EQUIP+

    NARCIS (Netherlands)

    Dittrich, M.G.

    2006-01-01

    Noise control of different types of outdoor machinery covered by EU Directive 2000/14/EC such as construction machines, generators and other equipment powered by internal combustion engines requires knowledge of the noise path model and the potential noise control measures. As there is often a

  3. Narrowband active noise control system with online secondary-path modeling%一种含次级通道在线辨识的窄带主动噪声控制系统

    Institute of Scientific and Technical Information of China (English)

    孙金玮; 孙琳; 刘剑; 于志

    2011-01-01

    The principle, importance and development status of active noise control ( ANC) technology is introduced, which is based on canceling the sinusoidal noise generated by rotating machines. This technique especially takes the lower frequency noise components less than 500 Hz or 600 Hz as the target, and the hazards of the acoustic noises are analyzed. In real-life sound field, Lhe control system usually is not stable because the system is easy to be affected by the power of primary noise, amplitude of residual noise and etc. In this paper, based on the results obtained from analyzing the convergence conditions of the control system, a scale factor is introduced to the residual noise signal and consequently the system model is improved. To verify the effectiveness of the modified system, a high-speed digital signal processor ( DSP)-based active noise controller with online secondary-path modeling is designed to suppress the narrowband noise in a one-dimensional duct. Experimental results show that the noise reduction is up to 16 dB around frequency band of 250 Hz.%分析了噪声危害设备产生的谐波噪声,特别是以500 Hz或600 Hz以下的低频成分为对象,介绍了主动噪声控制(ANC)技术的原理、意义及发展现状.在实际声学场所,由于控制系统易受初级噪声功率、残余噪声幅值等因素影响而不稳定.在分析控制系统收敛条件的基础上,通过对系统误差引入一个比例因子从而改进系统模型,并以一维管道为实验平台,基于高速数字信号处理器(DSP)设计了含次级通道在线辨识的主动噪声控制器.实验结果表明,在250 Hz左右的频段上能够达到16 dB的降噪效果.

  4. Noise Control in Propeller-Driven Aircraft

    Science.gov (United States)

    Rennison, D. C.; Wilby, J. F.

    1983-01-01

    Analytical model predicts noise levels inside propeller-driven aircraft during cruise at mach 0.8. Double wall sidewalls minimize interior noise and weight. Model applied to three aircraft with fuselages of different size (wide-body, narrow-body, and small-diameter) to determine noise reductions required to achieve A-weighted sound level not to exceed 80 dB.

  5. Active harmonic noise control in three-dimensional space and simulation%简谐噪声在三维空间的主动控制及仿真

    Institute of Scientific and Technical Information of China (English)

    张穴; 张方

    2011-01-01

    The 3D space active noise control technology is a hot spot issue in the field of noise control,which has great significance in reducing the noise of aircraft or vehicle. Put forward a method of precise control harmonic noise in 3D space.First of all,modeling and meshing for the 3D space. The quadratic sum of sound pressure of all nodes is used as an error criterion. Then,we obtain the secondary sound source strength in the case that the error criterion is minimal, Finally, we simulate the active noise cortrol system based on this method. The simulation results show that the system can get the largest noise reduction amount up to 15~30 dB,which validates the effectiveness of this method.%三维空间的噪声主动控制技术是近年来噪声控制领域研究的一个热点问题,对于降低飞机或车辆里的噪声水平有很大意义.提出了一种对于简谐噪声在三维空间进行精确控制的方法,先对三维空间建立几何模型,并且对几何模型进行网格划分,误差准则取所有节点处的声压平方和,然后在误差准则取得最小值的情况下,计算出次级声源的强度.最后对基于该方法设计的噪声主动控制系统进行仿真,仿真结果表明系统有15~30 dB的最大降噪量,从而验证了该方法的有效性.

  6. Model based monitoring for industrial and traffic noise control

    NARCIS (Netherlands)

    Eerden, F.J.M. van der; Binnerts, B.; Graafland, F.

    2015-01-01

    Noise control starts by understanding the actual noise situation. Especially for situations where the distance between industrial and traffic noise sources and a local community is in the order of one kilometer or more, it may not be clear what sources are the main contributors to annoyance. Then a

  7. Traffic noise and vehicle movement at a controlled intersection

    NARCIS (Netherlands)

    Salomons, E.M.

    2014-01-01

    Traffic noise at an intersection controlled by traffic lights shows noise level variations due to the alternating green and red lights for the different trafficstreams. Noise peaks caused by automobiles pulling up or passing by at highspeed may be quite annoying for people living near the intersecti

  8. Research on Noise Control for Ventilators with Resonance

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source was found to be the dynamic noise at the outlet of the diffuser. The frequency of its peak value was 250 Hz. A special brick with a resonant frequency of 250 Hz was designed to eliminate this noise. The diffusion of a lower frequency noise has been successfully controlled by the installation of a noise-eliminating tower above the diffuser outlet. The detection results show that the noise in the nearby residential area has been lowered to an average 55.3dB(A) in the daytime from 69.8dB(A) and to 48.4dB(A) at night from 65.8dB(A).

  9. Air injection vacuum blower noise control

    Energy Technology Data Exchange (ETDEWEB)

    Mose, Tyler L.A.; Faszer, Andrew C. [Noise Solutions Inc. (Canada)], email: tmose@noisesolutions.com, email: afaszer@noisesolutions.com

    2011-07-01

    Air injection vacuum blowers, with applications in waste removal, central vacuum systems, and aeration systems, are widely used when high vacuum levels are required. Noise generated by those blowers must be addressed for operator health and residential disturbance. This paper describes a project led by Noise Solutions Inc., to identify noise sources in a blower, and design and test a noise mitigation system. First the predominant noise sources in the blower must be determined, this is done with a sound level meter used to quantify the contribution of each individual noise source and the dominant tonal noise from the blower. Design of a noise abatement system must take into account constraints arising from blower mobile use, blower optimal performance, and the resulting overall vibration of the structure. The design was based on calculations from the sound attenuation of a reactive expansion chamber and two prototypes of custom silencers were then tested, showing a significant noise reduction both in total sound levels and tonal noise.

  10. 燃料电池汽车空辅系统噪声有源控制技术%Active Noise Control Technology of Air Auxiliary System in Fuel Cell Vehicles

    Institute of Scientific and Technical Information of China (English)

    胡佳杰; 左曙光; 何吕昌; 张孟浩

    2013-01-01

      燃料电池汽车(FCV)的动力系统及噪声特性与传统汽车相比有着很大差异,其中空气辅助系统已成为主要的噪声源。虽然有源噪声控制(ANC)是近年来的研究热点;但是,由于噪声源与环境的时变性,对空辅系统的中低频段噪声更有效的对策是使用自适应有源噪声控制技术(AANC)。在归纳总结有源噪声控制技术的发展进程及基本原理的基础上,阐述近年来有源噪声控制的研究现状,并重点分析关注自适应算法的研究进展;由此对自适应有源噪声控制在燃料电池汽车空辅系统减振降噪方面的应用前景进行预测和展望。%The power system and its noise characteristic of Fuel Cell Vehicle (FCV) are quite different from those of traditional cars. In FCV, the air auxiliary system becomes one of the main noise sources. In recent years, active noise control (ANC) has become a research focus. It has advantages for the traditional passive noise control in middle-and low-frequency range. However, because of the time-variation property of noise sources and environments, it is necessary to use adaptive active noise control (AANC) in middle-and low-frequency noise control of the air auxiliary system in FCV. In this paper, the development progress of ANC technology was summarized, and the research of ANC in recent years was expatiated. Analysis was focused on the research progress of adaptive algorithm. Finally, the prospect of the ANNC application in the field of vibration and noise reduction of the air auxiliary system in FCV was forecasted.

  11. Study on noise prediction model and control schemes for substation.

    Science.gov (United States)

    Chen, Chuanmin; Gao, Yang; Liu, Songtao

    2014-01-01

    With the government's emphasis on environmental issues of power transmission and transformation project, noise pollution has become a prominent problem now. The noise from the working transformer, reactor, and other electrical equipment in the substation will bring negative effect to the ambient environment. This paper focuses on using acoustic software for the simulation and calculation method to control substation noise. According to the characteristics of the substation noise and the techniques of noise reduction, a substation's acoustic field model was established with the SoundPLAN software to predict the scope of substation noise. On this basis, 4 reasonable noise control schemes were advanced to provide some helpful references for noise control during the new substation's design and construction process. And the feasibility and application effect of these control schemes can be verified by using the method of simulation modeling. The simulation results show that the substation always has the problem of excessive noise at boundary under the conventional measures. The excess noise can be efficiently reduced by taking the corresponding noise reduction methods.

  12. Design and Realization of Active Noise Control System Based on TMS320VC5509 DSP%基于TMS320VC5509 DSP的有源噪声控制系统设计与实现

    Institute of Scientific and Technical Information of China (English)

    张有鹏; 陈春明; 李国海

    2011-01-01

    介绍了有源噪声控制技术的理论基础和算法,以自适应有源噪声前馈控制系统为研究核心,选用TMS320VC5509 DSP作为控制器,给出了系统的硬件解决方案,并用C语言编程在硬件系统上实现了基于FX-LMS算法的有源噪声实时控制.对800 Hz单频噪声的实验结果表明系统可降低噪声幅度9 dB.%The foundational theory and algorithm of active noise control technology are introduced. The feed-forward a-daptive active noise control ( AANC) system is presented, the hardware solution of the system is proposed by selecting TMS320VC5509 DSP as the controller. Using the C language, the active noise real-time control system is realized based on the FX-LMS algorithm. It's proved that 9dB cancellation on 800 Hz is achieved by the experiment.

  13. Applications of the Piezoelectric Active Control to the Reduction of Vibration and Noise%压电主动控制在减振和降噪中的应用

    Institute of Scientific and Technical Information of China (English)

    吴昱廷; 黄华林; 徐俊; 史翔; 魏晓勇

    2011-01-01

    The piezoelectric active control has broad prospects for the reduction of vibration and noise. Three solutions of the vibration reduction of the simply-supported beam, the noise reduction of the aluminum plate and the vibration reduction of the base plate have been designed in this paper. The experimental results showed that the reductions of the vibration and noise for the single signal frequency were all up to about 90% , and it proved that the reduction of the vibration and noise for the single frequency by using the piezoelectric active control was feasible and the performance was significant.%利用压电主动控制进行减振和降噪实验具有广阔的发展前景.该文设计了3个相关的方案:简支梁的减振、铝板的降噪和基座的减振.实验结果显示,对于单频信号减振和降噪的效果均可达90%,证明了通过压电主动控制来实现单频的减振和降噪的可行性和显著性.

  14. Quality control in digital mammography: the noise components

    Energy Technology Data Exchange (ETDEWEB)

    Leyton, Fernando [Universidade de Tarapaca, Arica (Chile). Centro de Estudios en Ciencias Radiologicas; Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Nogueira, Maria do Socorro, E-mail: mnogue@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Duran, Maria Paz [Clinica Alemana, Santiago (Chile). Dept. de Radiologia; Dantas, Marcelino, E-mail: marcelino@inb.gov.b [Industrias Nucleares do Brasil (INB), Caldas, MG (Brazil). Unidade de Tratamento de Minerios; Ubeda, Carlos, E-mail: cubeda@uta.c [Universidade de Tarapaca, Arica (Chile). Fac. de Ciencias de la Salud

    2011-07-01

    To measure the linearity of the detector and determine the noise components (quantum, electronic and structural noise) that contributed to losing image quality and to determine the signal noise ratio (SNR) and contrast noise ratio (CNR). This paper describes the results of the implementation of a protocol for quality control in digital mammography performed in two direct digital mammography equipment (Hologic, Selenia) in Santiago of Chile. Shows the results of linearity and noise analysis of the images which establishes the main cause of noise in the image of the mammogram to ensure the quality and optimize procedures. The study evaluated two digital mammography's Selenia, Hologic (DR) from Santiago, Chile. We conducted the assessment of linearity of the detector, the signal noise ratio, contrast noise ratio and was determined the contribution of different noise components (quantum, electronics and structural noise). Used different thicknesses used in clinical practice according to the protocol for quality control in digital mammography of Spanish society of medical physics and NHSBSP Equipment Report 0604 Version 3. The Selenia mammography software was used for the analysis of images and Unfors Xi detector for measuring doses. The mammography detector has a linear performance, the CNR and SNR did not comply with the Protocol for the thicknesses of 60 and 70 mm. The main contribution of the noise corresponds to the quantum noise, therefore it is necessary to adjust and optimize the mammography system. (author)

  15. Noise exposure immediately activates cochlear mitogen-activated protein kinase signaling

    Directory of Open Access Journals (Sweden)

    Kumar N Alagramam

    2014-01-01

    Full Text Available Noise-induced hearing loss (NIHL is a major public health issue worldwide. Uncovering the early molecular events associated with NIHL would reveal mechanisms leading to the hearing loss. Our aim is to investigate the immediate molecular responses after different levels of noise exposure and identify the common and distinct pathways that mediate NIHL. Previous work showed mice exposed to 116 decibels sound pressure level (dB SPL broadband noise for 1 h had greater threshold shifts than the mice exposed to 110 dB SPL broadband noise, hence we used these two noise levels in this study. Groups of 4-8-week-old CBA/CaJ mice were exposed to no noise (control or to broadband noise for 1 h, followed by transcriptome analysis of total cochlear RNA isolated immediately after noise exposure. Previously identified and novel genes were found in all data sets. Following exposure to noise at 116 dB SPL, the earliest responses included up-regulation of 243 genes and down-regulation of 61 genes, while a similar exposure at 110 dB SPL up-regulated 155 genes and down-regulated 221 genes. Bioinformatics analysis indicated that mitogen-activated protein kinase (MAPK signaling was the major pathway in both levels of noise exposure. Nevertheless, both qualitative and quantitative differences were noticed in some MAPK signaling genes, after exposure to different noise levels. Cacna1b , Cacna1g , and Pla2g6 , related to calcium signaling were down-regulated after 110 dB SPL exposure, while the fold increase in the expression of Fos was relatively lower than what was observed after 116 dB SPL exposure. These subtle variations provide insight on the factors that may contribute to the differences in NIHL despite the activation of a common pathway.

  16. Development of Corner Active Noise Control System on Simulated Cockpit of J6-Ⅲ Plane.%J6-Ⅲ模拟座舱屋角主动消声系统的研制

    Institute of Scientific and Technical Information of China (English)

    余文斌; 郭金洋; 陈晓勤; 郑学文

    2011-01-01

    目的 研制对低频噪声有较好消声作用的J6-Ⅲ模拟座舱屋角主动消声系统.方法 通过将简正振动模式分析理论应用于驾驶舱内声场分析研究中,确定消声系统的传输曲线,利用声电反馈控制系统来实现,并在歼6-Ⅲ歼击机模拟座舱进行实际测量.结果 系统对歼6-Ⅲ飞机模拟座舱内500 Hz窄带噪声主动消声效果超过8 dB;作用范围65 Hz-1000 Hz.结论 主动消声对低频噪声作用明显,本系统推广范围大,但是实际应用尚有差距.%Objective To develop the corner active noise control(ANC) system on the simulated cockpit of J6-Ⅲ plane for further eliminating low frequency noise.Methods Based on the normal mode analytic theory, the sound field of simulated cockpit was analyzed and studied.The transfer curve of active noise control system was determined.This system was realized with the acoustic-electric feedback control system.Then it was practically tested in the simulated cockpit of J6-Ⅲ plane.Results This ANC system could reduce random noise over 8dB in 500 Hz and work from 65 Hz to 1000 Hz.Conclusion The effect of this ANC system on low frequency noise is obvious.It can work well in many fields, but there is a distance to be applied in practical flight arm.

  17. Cost effective noise control in the oil and gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Meredith, Dave [Kinetics Noise Control Inc. (United States)], email: dmeredith@kineticsnoise.com

    2011-07-01

    Infrastructures in the oil and gas industry are often sources of excessive noise and vibration. This paper focuses on the work of Kinetics Noise Control, Inc. (KNC), an independent consulting firm specialized in corrective noise and vibration control products, to ensure that their clients' operations meet government and industry regulations. Using examples of different projects that KNC has been involved with in the oil and gas industry, the author presents new designs and approaches for reducing noise pollution. Noise and vibration control strategy should be integral parts of the concept design phase and aim at meeting regulatory requirements without loss of overall efficiency. To do this, specific elements, such as an extensive analysis of noise and vibration sources, site environmental conditions, the acoustics of the infrastructures, and of the materials used must be taken into account.

  18. 多通道自适应主动噪声控制系统设计及实验%Design and Experiment of Multi-Channel Adaptive Active Noise Control System

    Institute of Scientific and Technical Information of China (English)

    王春云; 吴亚锋; 杨浩; 储妮晟

    2011-01-01

    设计了一种多路自适应主动噪声控制系统,该系统具有4路误差输入和2路抵消输出,详细介绍了系统的设计方法、结构组成和控制原理.利用该系统,在一个普通封闭房间分别完成了对160 Hz单频正弦噪声,三阶谐频噪声和实际录取的某型号潜艇噪声进行了控制实验,分别取得了20 dB、10 dB和8 dB的降噪效果,验证了该系统的可行性和有效性.%A multi-channel self-adaptive active noise control system is designed. It has four error inputs and two offset outputs. Furthermore, the structure, design method and control principle are introduced in detail. Using this system, 160 Hz single-frequency sine noise, the third order harmonic sinusoidal noise and the actual noise from a certain type of submarine are experimented respectively in an ordinary closed room and the effect of 8 dB, 10 dB and 20 dB are obtained respectively. The experimental result verifies the feasibility and effectiveness of the system.

  19. 螺桨飞机舱内噪声地面模拟及其主动控制%Ground-simulation of Propeller Induced Airplane Cabin Noise and Its Active Control

    Institute of Scientific and Technical Information of China (English)

    吴亚锋; 李江红; 戴杏珍

    2001-01-01

    This paper presents the analogized methods and the active controlexperiments of the cabin noise for a propeller airplane.In a Y7 test airplane,the cabin noise is analogized by an exciter to structure-borne noise and by a loudspeaker to air-borne noise.A multi-channel adaptive control system is developed and used to attenuate the analogized noise field and satisfied results are obtained in the controlled area.%本文介绍螺桨飞机舱内噪声的地面模拟方法和主动控制实验。在一架运七试验机上,激振器和扬声器分别被用来模拟由螺桨旋转在舱内引起的结构和气动噪声。一个多通道自适应控制系统被应用于该模拟声场的主动控制实验,并在控制区域取得了满意的降噪效果。

  20. Stability of Controlled Hamilton Systems Excited by Gaussian White Noise

    Institute of Scientific and Technical Information of China (English)

    SHANG Mei; GUO Yong-xin; MEI Feng-xiang

    2008-01-01

    A new method is introduced in this paper. This method can be used to study the stability of controlled holonomic Hamilton systems under disturbance of Gaussian white noise. At first, the motion equation of controlled holonomic Hamilton systems excited by Gaussian noise is formulated. A theory to stabilize the system is provided. Finally, one example is given to illustrate the application procedures.

  1. Hybrid Active/Passive Jet Engine Noise Suppression System

    Science.gov (United States)

    Parente, C. A.; Arcas, N.; Walker, B. E.; Hersh, A. S.; Rice, E. J.

    1999-01-01

    A novel adaptive segmented liner concept has been developed that employs active control elements to modify the in-duct sound field to enhance the tone-suppressing performance of passive liner elements. This could potentially allow engine designs that inherently produce more tone noise but less broadband noise, or could allow passive liner designs to more optimally address high frequency broadband noise. A proof-of-concept validation program was undertaken, consisting of the development of an adaptive segmented liner that would maximize attenuation of two radial modes in a circular or annular duct. The liner consisted of a leading active segment with dual annuli of axially spaced active Helmholtz resonators, followed by an optimized passive liner and then an array of sensing microphones. Three successively complex versions of the adaptive liner were constructed and their performances tested relative to the performance of optimized uniform passive and segmented passive liners. The salient results of the tests were: The adaptive segmented liner performed well in a high flow speed model fan inlet environment, was successfully scaled to a high sound frequency and successfully attenuated three radial modes using sensor and active resonator arrays that were designed for a two mode, lower frequency environment.

  2. Fan Noise Control Using Herschel-quincke Resonators

    Science.gov (United States)

    Burdisso, Ricardo A.; Ng, Wing F.; Provenza, Andrew (Technical Monitor)

    2003-01-01

    The research effort proposed for this NASA NRA is mainly experimental. In addition, Virginia Tech is working in partnership with Goodrich Aerospace, Aerostructures Group for the analytical development needed to support the experimental endeavor, i.e. model development, design, and system studies. In this project, Herschel-Quincke (HQ)liner technology experiments will be performed at the NASA Glenn Active Noise Control Fan (ANCF) facility. A schematic of both inlet and aft HQ-liner systems installed in the ANCF rig as well as a picture of the Glenn facility is shown. The main goal is to simultaneously test in both the inlet and bypass duct sections. The by-pass duct will have HQ-systems in both the inner and outer duct walls. The main advantages of performing tests at the ANCF facility are that the effect of the inlet HQ-system on the by-pass HQ-system and vice versa, can be accurately determined from the in-duct modal data. Another significant advantage is that it offers the opportunity to assess (on a common basis) the proposed noise reduction concept on the ANCF rig which in the past has been used for assessing other active and passive noise reduction strategies.

  3. Adaptive Intelligent Ventilation Noise Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA need for quiet on-orbit crew quarters (CQ), Physical Optics Corporation (POC) proposes to develop a new Adaptive Intelligent Ventilation Noise...

  4. Adaptive Intelligent Ventilation Noise Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address NASA needs for quiet crew volumes in a space habitat, Physical Optics Corporation (POC) proposes to develop a new Adaptive Intelligent Ventilation Noise...

  5. Brownian Ratchets: Transport Controlled by Thermal Noise

    Science.gov (United States)

    Kula, J.; Czernik, T.; Łuczka, J.

    1998-02-01

    We analyze directed transport of overdamped Brownian particles in a 1D spatially periodic potential that are subjected to both zero-mean thermal equilibrium Nyquist noise and zero-mean exponentially correlated dichotomous fluctuations. We show that particles can reverse the direction of average motion upon a variation of noise parameters if two fundamental symmetries, namely, the reflection symmetry of the spatial periodic structure, and the statistical symmetry of dichotomous fluctuations, are broken. There is a critical thermal noise intensity Dc, or equivalently a critical temperature Tc, at which the mean velocity of particles is zero. Below Tc and above Tc particles move in opposite directions. At fixed temperature, there is a region of noise parameters in which particles of different linear size are transported in opposite directions.

  6. Controlling noise in plasmonic structures with gain

    Science.gov (United States)

    Vyshnevyy, A. A.; Fedyanin, D. Yu.

    2017-09-01

    Loss compensation by gain medium gives the possibility to exploit subwavelength confinement of light in plasmonic nanostructures and construct nanoscale plasmonic circuits. However, due to fundamentally unavoidable spontaneous emission from the gain medium, lossless waveguides suffer from strong photonic noise, which limits their practical applications. Here we demonstrate the possibility of significant decrease of the noise level while preserving physical dimensions of lossless plasmonic waveguides with gain. Our findings are aimed at extending the communication capabilities of on-chip plasmonic networks.

  7. 多路分离式PID模数混合主动噪声控制技术研究%Study on Multi-Channel Active Noise Control with Analogue-Digital Mixed PID

    Institute of Scientific and Technical Information of China (English)

    李世振; 李功宇; 母向东

    2011-01-01

    Aiming at the characteristics of multi-harmonic frequency noise that most of electromechanical products possess, a new approach called multi-channel active noise control with analogue-digital mixed PID technique is proposed in this paper.This approach combines both multi-analogue filtering and digital phase automatic tracking PID techniques.A test of noise reduction in the duct was carried out.The results show that approach performs well for reducing multi-harmonic frequency noise in the duct.Due to the difficulty in application of the active noise control technique in 3D sound field, the sound concentrator is used to transfer the sound field from 3D into 1D in order to apply the new approach.Meanwhile, the dry-type transformer is taken as an experiment object to verify this new approach.%针对机电产品具有的多谐频噪声特性,提出一种多路分离式模拟滤波与数字PID相位自动跟踪相结合的模数混合主动噪声控制方法,消声实验结果表明该方法在多谐频管道噪声消除中稳定有效.针对目前三维声场主动噪声控制工程应用难的状况,提出利用通风道或窗结构将三维声场聚声为一维声场实现主动噪声控制的工程技术并以干式变压器为对象进行探索研究.

  8. Industrial noise control: Some case histories, volume 1

    Science.gov (United States)

    Hart, F. D.; Neal, C. L.; Smetana, F. O.

    1974-01-01

    A collection of solutions to industrial noise problems is presented. Each problem is described in simple terms, with noise measurements where available, and the solution is given, often with explanatory figures. Where the solution rationale is not obvious, an explanatory paragraph is usually appended. As a preface to these solutions, a short exposition is provided of some of the guiding concepts used by noise control engineers in devising their solutions.

  9. Resonant Activation Induced by Four-Value Noise

    Institute of Scientific and Technical Information of China (English)

    LIU Hui; HAN Yin-Xia; HOU De-Fu; LI Jing-Hui; LI Jia-Rong

    2008-01-01

    The phenomenon of the resonant activation (RA) of a particle over a fluctuating potential barrier with a four-value noise is investigated. It is shown that the mean first passage time (MFPT) displays six minima as the function of the transition rates γ1, γ2, γ3, γ4,γ5, and γ6 of the four-value noise, respectively. In addition, the effect of other parameters of the system, such as the noise strength D of the additive Gaussian white noise and the parameter value a,b, c, and d of the four-value noise, on the RAs is also investigated.

  10. Hybrid Feedforward-Feedback Noise Control Using Virtual Sensors

    Science.gov (United States)

    Bean, Jacob; Fuller, Chris; Schiller, Noah

    2016-01-01

    Several approaches to active noise control using virtual sensors are evaluated for eventual use in an active headrest. Specifically, adaptive feedforward, feedback, and hybrid control structures are compared. Each controller incorporates the traditional filtered-x least mean squares algorithm. The feedback controller is arranged in an internal model configuration to draw comparisons with standard feedforward control theory results. Simulation and experimental results are presented that illustrate each controllers ability to minimize the pressure at both physical and virtual microphone locations. The remote microphone technique is used to obtain pressure estimates at the virtual locations. It is shown that a hybrid controller offers performance benefits over the traditional feedforward and feedback controllers. Stability issues associated with feedback and hybrid controllers are also addressed. Experimental results show that 15-20 dB reduction in broadband disturbances can be achieved by minimizing the measured pressure, whereas 10-15 dB reduction is obtained when minimizing the estimated pressure at a virtual location.

  11. Wavelet Adaptive Algorithm and Its Application to MRE Noise Control System

    Directory of Open Access Journals (Sweden)

    Zhang Yulin

    2015-01-01

    Full Text Available To address the limitation of conventional adaptive algorithm used for active noise control (ANC system, this paper proposed and studied two adaptive algorithms based on Wavelet. The twos are applied to a noise control system including magnetorheological elastomers (MRE, which is a smart viscoelastic material characterized by a complex modulus dependent on vibration frequency and controllable by external magnetic fields. Simulation results reveal that the Decomposition LMS algorithm (D-LMS and Decomposition and Reconstruction LMS algorithm (DR-LMS based on Wavelet can significantly improve the noise reduction performance of MRE control system compared with traditional LMS algorithm.

  12. 脉冲噪声的非线性变换有源控制算法研究%Research active control algorithm based on nonlinear transform of impulsive noise

    Institute of Scientific and Technical Information of China (English)

    李沛; 张景荣

    2016-01-01

    α稳定分布模型是描述脉冲噪声的最佳理论工具,研究了对称α稳定分布脉冲噪声的有源控制;对基于非线性变换的脉冲噪声有源控制算法进行了推导与分析,并对FXSigmod算法进行了计算机仿真,用实验证实算法消除噪声的效果。该算法无需估测阈值,容易实现,连续更新性能好,可快速有效抑制脉冲噪声。%The alpha stable distribution provides a strong theoretical tool for the analysis of the non‐Gaussian impulsive noise signals .Active control of symmetricαstable distribution impulsive noise is studied .Impulsive noise algorithm based on nonlinear transform is derived and analyzed ,the computer simulation was carried out to validate FxSigmod algorithm .Simulation results prove the effectiveness of the algorithm .It does not need the parameter selection and thresholds estimation .it is easy to implement .Continuous update performance of algorithm is good ,which can restrain impulsive noise quickly and efficiently .

  13. Noise control for rapid transit cars on elevated structures

    Science.gov (United States)

    Hanson, C. E.

    1983-03-01

    Noise control treatments for the propulsion motor noise of rapid transit cars on concrete elevated structures and the noise reduction from barrier walls were investigated by using acoustical scale models and supplemented by field measurements of noise from trains operated by the Port Authority Transportation Corporation (PATCO) in New Jersey. The results show that vehicle skirts and undercar sound absorption can provide substantial cost-effective reductions in propulsion noise at the wayside of transit systems with concrete elevated guideways. The acoustical scale model noise reductions applied to PATCO vehicles on concrete elevated structures show reductions in the A-weighted noise levels of 5 dB for undercar sound absorption, 5 dB for vehicle skirts, and 10 dB for combined undercar absorption and vehicle skirts. Acoustical scale model results for sound barrier walls lined with absorptive treatment showed reductions from 7 dB to 12 dB of noise from vehicles in the far track, depending on the height of the wall, and reductions from 12 dB to 20 dB of noise from vehicles on the near track. Transit vehicles at high speeds where propulsion system noise dominates are 7 dB(A) noisier at 50 ft on concrete elevated structures than on at-grade on tie and ballast. Of this amount, 3 dB is due to loss of ground effect, and 4 dB is due to the absence of undercar absorption provided by ballast.

  14. Noise Control in Gene Regulatory Networks with Negative Feedback.

    Science.gov (United States)

    Hinczewski, Michael; Thirumalai, D

    2016-07-01

    Genes and proteins regulate cellular functions through complex circuits of biochemical reactions. Fluctuations in the components of these regulatory networks result in noise that invariably corrupts the signal, possibly compromising function. Here, we create a practical formalism based on ideas introduced by Wiener and Kolmogorov (WK) for filtering noise in engineered communications systems to quantitatively assess the extent to which noise can be controlled in biological processes involving negative feedback. Application of the theory, which reproduces the previously proven scaling of the lower bound for noise suppression in terms of the number of signaling events, shows that a tetracycline repressor-based negative-regulatory gene circuit behaves as a WK filter. For the class of Hill-like nonlinear regulatory functions, this type of filter provides the optimal reduction in noise. Our theoretical approach can be readily combined with experimental measurements of response functions in a wide variety of genetic circuits, to elucidate the general principles by which biological networks minimize noise.

  15. AIR DISTRIBUTION NOISE CONTROL IN CRITICAL AUDITORIUMS.

    Science.gov (United States)

    HOOVER, R.M.

    THE ACHIEVEMENT OF EXTREMELY LOW AIR-CONDITIONING NOISE LEVELS REQUIRED FOR MODERN AUDITORIUMS ARE THE RESULT OF CAREFUL PLANNING AND THOROUGH DETAILING. PROBLEMS FACED AND TECHNIQUES USED IN ARRIVING AT LEVELS AS LOW AS NC-15 FOR A SINGLE SYSTEM SERVING A HALL ARE DESCRIBED. SIX CASE HISTORIES ARE EXAMINED AND THE FOLLOWING OBSERVATIONS ARE…

  16. Optimization of Resilient Wheels for Rolling Noise Control

    Science.gov (United States)

    BOUVET, PASCAL; VINCENT, NICOLAS; COBLENTZ, ARNAUD; DEMILLY, FRANÇOIS

    2000-03-01

    Resilient wheels are currently used on light rail systems such as tramways to prevent squealing noise and to reduce impact noise. On the other hand, they are rarely found on main lines (passenger rolling stock and freight rolling stock). Although manufacturers often claim that resilient wheels are favourable for rolling noise control, no extensive theoretical investigation confirming this statement has been published to date. In this paper, it is shown how resilient wheels can be effectively optimised in order to reduce rolling noise emission, compared to a conventional monobloc wheel. A preliminary analysis of the physical phenomena accounting for rolling noise generation emphasizes the key design parameters affecting both wheel and radiation. These parameters are the radial dynamic stiffness and damping loss factor of the rubber layer. The tread mass is also relevant. The influence of these design parameters is then qualified by a parametric study performed with the TWINS software. An optimum radial dynamic stiffness of the resilient layer is found which depends on operating conditions. Reductions in overall rolling noise up to 3 dB(A) are calculated for the configurations investigated. However, poor selection of the design parameters can lead to a noise increase compared to a standard monobloc wheel. It is also shown that a proper design for rolling noise control will not affect wheel efficiency with regard to squeal noise.

  17. An improved affine projection algorithm for active noise cancellation

    Science.gov (United States)

    Zhang, Congyan; Wang, Mingjiang; Han, Yufei; Sun, Yunzhuo

    2017-08-01

    Affine projection algorithm is a signal reuse algorithm, and it has a good convergence rate compared to other traditional adaptive filtering algorithm. There are two factors that affect the performance of the algorithm, which are step factor and the projection length. In the paper, we propose a new variable step size affine projection algorithm (VSS-APA). It dynamically changes the step size according to certain rules, so that it can get smaller steady-state error and faster convergence speed. Simulation results can prove that its performance is superior to the traditional affine projection algorithm and in the active noise control (ANC) applications, the new algorithm can get very good results.

  18. Evaluation of Neural Networks Performance in Active Cancellation of Acoustic Noise

    Directory of Open Access Journals (Sweden)

    Mehrshad Salmasi,

    2014-12-01

    Full Text Available Active Noise Control (ANC works on the principle of destructive interference between the primary disturbance field heard as undesired noise and the secondary field which is generated from control actuators. In the simplest system, the disturbance field can be a simple sine wave, and the secondary field is the same sine wave but 180 degrees out of phase. This research presents an investigation on the use of different types of neural networks in active noise control. Performance of the multilayer perceptron (MLP, Elman and generalized regression neural networks (GRNN in active cancellation of acoustic noise signals is investigated and compared in this paper. Acoustic noise signals are selected from a Signal Processing Information Base (SPIB database. In order to compare the networks appropriately, similar structures and similar training and test samples are deduced for neural networks. The simulation results show that MLP, GRNN, and Elman neural networks present proper performance in active cancellation of acoustic noise. It is concluded that Elman and MLP neural networks have better performance than GRNN in noise attenuation. It is demonstrated that designed ANC system achieve good noise reduction in low frequencies.

  19. Noise control zone for a periodic ducted Helmholtz resonator system.

    Science.gov (United States)

    Cai, Chenzhi; Mak, Cheuk Ming

    2016-12-01

    This paper presents a theoretical study of the dispersion characteristics of sound wave propagation in a periodic ducted Helmholtz resonator (HR) system. The predicted result fits well with a numerical simulation using a finite element method. This study indicates that for the same system, no matter how many HRs are connected or what the periodic distance is, the area under average transmission loss T L¯ curves is always the same. The broader the noise attenuation band, the lower the peak attenuation amplitude. A noise control zone compromising the attenuation bandwidth or peak amplitude is proposed for noise control optimization.

  20. Using VAPEPS for noise control on Space Station Freedom

    Science.gov (United States)

    Badilla, Gloria; Bergen, Thomas; Scharton, Terry

    1991-01-01

    Noise environmental control is an important design consideration for Space Station Freedom (SSF), both for crew safety and productivity. Acoustic noise requirements are established to eliminate fatigue and potential hearing loss by crew members from long-term exposure and to facilitate speech communication. VAPEPS (VibroAcoustic Payload Environment Prediction System) is currently being applied to SSF for prediction of the on-orbit noise and vibration environments induced in the 50 to 10,000 Hz frequency range. Various sources such as fans, pumps, centrifuges, exercise equipment, and other mechanical devices are used in the analysis. The predictions will be used in design tradeoff studies and to provide confidence that requirements will be met. Preliminary predictions show that the required levels will be exceeded unless substantial noise control measures are incorporated in the SSF design. Predicted levels for an SSF design without acoustic control treatments exceed requirements by 25 dB in some one-third octave frequency bands.

  1. Environmental noise alters gastric myoelectrical activity: Effect of age

    Institute of Scientific and Technical Information of China (English)

    James S Castle; Jin-Hong Xing; Mark R Warner; Mark A Korsten

    2007-01-01

    AIM: To evaluate the effect of age and acoustic stress on gastric myoelectrical activity (GMA) and autonomic nervous system function,METHODS: Twenty-one male subjects (age range 22-71years, mean 44 years) were recruited and exposed, in random order, to three auditory stimuli (Hospital noise,conversation babble and traffic noise) after a 20-min baseline. All periods lasted 20 min and were interspersed with a 10 min of recovery. GMA was obtained using a Synectics Microdigitrapper. Autonomic nerve function was assessed by monitoring blood pressure and heart rate using an automatic recording device.RESULTS: Dominant power tended to decrease with increase of age (P<0.05). The overall percentage of three cycle per minute (CPM) activity decreased during exposure to hospital noise (12.0%, P < 0.05), traffic noise (13.9%, P < 0.05), and conversation babble(7.1%). The subjects in the younger group (< 50 years)showed a consistent reduction in the percentage of 3CPM activity during hospital noise (22.9%, P < 0.05),traffic noise (19.0%, P < 0.05), and conversation babble(15.5%). These observations were accompanied by a significant increase in bradygastria: hospital noise (P< 0.05) and traffic noise (P < 0.05). In contrast, the subjects over 50 years of age did not exhibit a significant decrease in 3 CPM activity. Regardless of age, noise did not alter blood pressure or heart rate.CONCLUSION: GMA changes with age. Loud noise can alter GMA, especially in younger individuals. Our data indicate that even short-term exposure to noise may alter the contractility of the stomach.

  2. Noise, Worker Perception, and Worker Concentration in Timber Harvesting Activity

    Directory of Open Access Journals (Sweden)

    Efi Yuliati Yovi

    2012-01-01

    Full Text Available Timber harvesting activities are unquestionably related with high risk of work accidents and health disorders.Such activities were not only burdened the workers with heavy physical workloads due to uneasy workingenvironment, and massive work materials and tools, but also physiopsychologically burdened workers as theywere imposed with both mechanical and acoustic vibrations (noise produced by the chainsaw. However,  it is acommon practice that most of the workers still ignored the importance of the use of noise reduction devices suchas earmuff or ear plug.  This study was aimed to reveal the factual effects of noise on work concentration of theworkers to provide a scientific basis in supporting efforts in improving workers’ attitude.  The results confirmedthat chainsaw might produce noise during operation.  Noise intensities received by both right and left ears werenot significantly different, indicating that left-handed and normal workers received similar degree of noise inboth side of ears. Further, results also showed that there was a significant difference on the perception and workconcentration of chainsaw operators versus sedentary people to the noise.  These findings proved that hearingability of chainsaw operators had declined due to frequent noise exposure.Keywords: timber harvesting, physio-psychological disorder, noise, chainsaw

  3. Inter-noise 89 - Engineering for environmental noise control; Proceedings of the International Conference on Noise Control Engineering, Newport Beach, CA, Dec. 4-6, 1989. Vols. 1 & 2

    Science.gov (United States)

    Maling, George C., Jr.

    Recent advances in noise analysis and control theory and technology are discussed in reviews and reports. Topics addressed include noise generation; sound-wave propagation; noise control by external treatments; vibration and shock generation, transmission, isolation, and reduction; multiple sources and paths of environmental noise; noise perception and the physiological and psychological effects of noise; instrumentation, signal processing, and analysis techniques; and noise standards and legal aspects. Diagrams, drawings, graphs, photographs, and tables of numerical data are provided.

  4. The spatial structure of underwater noise due to shipping activities in the Celtic Sea

    Science.gov (United States)

    Chen, Feng; Shapiro, Georgy; Thain, Richard

    2014-05-01

    Underwater noise is now classed as pollution alongside chemical pollution and marine litter (MSFD, 2012). Underwater noise from man-made sources arises from a number of sources including shipping activities. There are numerous examples of sound-induced effects recorded for various marine mammals, either in controlled situations, or opportunistically (MSFD-GES, 2012). Broad or narrow band continuous sounds, as well as pulses, have been documented to cause effects ranging from slight behaviour change, to activity disruption, avoidance or abandonment of preferred habitat (see Clark et al., 2009). Underwater ambient noise generated by shipping activities has increased significantly over the past decades (e.g. Mcdonald et al., 2006). Noise from shipping is a major contributor to the ambient noise levels in ocean, particularly at low (

  5. Performance Analysis of Transfer function Based Active Noise Cancellation Method Using Evolutionary Algorithm

    Directory of Open Access Journals (Sweden)

    Prof. Vikas Gupta

    2014-01-01

    Full Text Available Due to the exponential increase of noise pollution, the demand for noise controlling system is also increases. Basically two types of techniques are used for noise cancellation active and passive. But passive techniques are inactive for low frequency noise, hence there is an increasing demand of research and developmental work on active noise cancellation techniques. In this paper we introduce a new method in the active noise cancellation system. This new method is the transfer function based method which used Genetic and Particle swarm optimization (PSO algorithm for noise cancellation. This method is very simple and efficient for low frequency noise cancellation. Here we analysis the performance of this method in the presence of white Gaussian noise and compare the results of Particle swarm optimization (PSO and Genetic algorithm. Both algorithms are suitable for different environment, so we observe their performance in different fields. In this paper a comparative study of Genetic and Particle swarm optimization (PSO is described with proper results. It will go in depth what exactly transfer function method, how it work and advantages over neural network based method

  6. Noise controlled synchronization in potassium coupled neural models

    DEFF Research Database (Denmark)

    Postnov, Dmitry E; Ryazanova, Ludmila S; Zhirin, Roman A;

    2007-01-01

    The paper applies biologically plausible models to investigate how noise input to small ensembles of neurons, coupled via the extracellular potassium concentration, can influence their firing patterns. Using the noise intensity and the volume of the extracellular space as control parameters, we...... show that potassium induced depolarization underlies the formation of noise-induced patterns such as delayed firing and synchronization. These phenomena are associated with the appearance of new time scales in the distribution of interspike intervals that may be significant for the spatio...

  7. Studying the Noise Control Engineering Protocols in Industry

    Directory of Open Access Journals (Sweden)

    Hamid Golshah

    1999-03-01

    Full Text Available Today, sound is one of the detrimental factors in the workplace and its harmful impact has been so important that scientists have named it “Noise Pollutions”. Hearing is one of the five senses of human being which is also a medium for communicating with other s and enjoying the pleasant feeling of listening to a piece of music. In spite of this, changes in the intensity and frequency of sound can make it annoying. Using Sound Level Meter to measure the dB of noise in the workplace and noise control principles will be discussed here.

  8. Design and control of noise-induced synchronization patterns

    CERN Document Server

    Kurebayashi, Wataru; Hasegawa, Mikio; Nakao, Hiroya

    2015-01-01

    We propose a method for controlling synchronization patterns of limit-cycle oscillators by common noisy inputs, i.e., by utilizing noise-induced synchronization. Various synchronization patterns, including fully synchronized and clustered states, can be realized by using linear filters that generate appropriate common noisy signals from given noise. The optimal linear filter can be determined from the linear phase response property of the oscillators and the power spectrum of the given noise. The validity of the proposed method is confirmed by numerical simulations.

  9. 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 ...

  10. Tunable Interior Rotorcraft Noise Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — CRG has recently developed a new class of shape memory polymers (SMP) that are electrically activated, as opposed to the more mature thermally activated SMPs....

  11. Tunable Interior Rotorcraft Noise Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — CRG has recently developed a new class of shape memory polymers (SMP) that are electrically activated, as opposed to the more mature thermally activated SMPs....

  12. Hybrid Fluid-borne Noise Control in Fluid-filled Pipelines

    Science.gov (United States)

    Pan, M.; Johnston, N.; Plummer, A.

    2016-09-01

    This article reports on an initial investigation of a hybrid fluid-borne noise control system in hydraulic pipelines. The hybrid system is built by integrating an active feedforward noise controller with passive tuned flexible hoses. The active attenuator is designed to cancel the dominant harmonic pressure pulsations in the fluid line, while the passive hose is tuned to attenuate the residual high frequency pulsations. The active attenuator can effectively decrease the fluid-borne noise by superimposing a secondary anti-phase control signal. Adaptive notch filters with the filtered-X least mean square algorithm were applied for the controller and a frequency-domain least mean square filter was used for the secondary path on-line identification. The transmission line model was used to model the pipeline, and a time-domain hose model which includes coupling of longitudinal wall and fluid waves was used to model the flexible hose. Simulation results show that very good noise cancellation was achieved using the proposed approach, which has several advantages over existing fluid-borne noise control systems, being effective for a wide range of frequencies without impairing the system dynamic response much. While the flexible hoses may be less effective than purpose-built passive silencers, they can form an inexpensive and practical solution in combination with active control.

  13. Parameter Optimization Analysis of the Secondary Acoustic Sources for Power Transformer Active Noise Control%电力变压器有源降噪中次级声源的参数优化分析

    Institute of Scientific and Technical Information of China (English)

    王学磊; 张黎; 李庆民; 娄杰; 孙晓阳

    2012-01-01

    为了获得较好的全局有源降噪效果,需合理布置次级声源,次级声源参数优化是电力变压器有源降噪技术研究中的核心问题。在分析有源降噪物理机制的基础上,建立了电力变压器的噪声辐射模型,得到变压器周围声场分布与噪声源、次级声源的关系。考虑实际工程需要,将次级声源参数分为2大类,并结合噪声辐射模型,从数目、位置、源强3方面对次级声源进行参数优化。鉴于位置和源强等参数间的交互影响关系,提出对固定参数和灵活参数进行交替优选,形成基于遗传算法的渐次搜索逼近策略。通过将具体算例与基于COMSOL软件的仿真结果相比较,表明该优化策略可获得较好的全局有源降噪效果。%In order to obtain a preferable global active noise reduction,thd most important thing is the reasonable arrangement of secondary source,so parameters optimization of the secondary sources is the principal issue for active noise control technology of power transformers.On the basis of the physical mechanism of active noise reduction,we established a noise radiation model for power transformers,and obtained the relationship between the sound field distribution around the transformer and the sound source including noise source and the secondary sources.With consideration of practical requirements and by combining with the noise radiation model,key parameters of the secondary sources were divided into two categories so as to realize parameter optimization in terms of source number,location,and strength.For interactive impacts resulted from secondary source location and strength,a scheme to alternately optimize the fixed parameters and the flexible parameters was proposed,and thereby agradual search approximation strategy based on genetic algorithm was further put forward.Case studies are compared with the simulation results by COMSOL software,showing that,with the proposed optimization strategy

  14. 脉冲噪声的最小均值M-估计有源控制算法%Least Mean M-estimate Algorithm for Active Control of Impulsive Noise

    Institute of Scientific and Technical Information of China (English)

    周浩; 周亚丽; 张奇志

    2013-01-01

    The classical Filter-x least mean square (Fx LMS) algorithm has been widely used in active noise control (ANC), but its performance would degrade dramatically if there were impulsive noise. In this paper, a new adaptive algorithm based on the concept of robust statistics was presented, whose objective function is the M-estimate function instead of the mean square error (MSE). Four different M-estimate functions, such as Huber function and Hampel’s three parts of re-descending M-estimate function, were used as the objective function and computer simulations were carried out to verify the efficiency of the presented algorithm for active impulsive noise control. The simulation results show that compared with the adding-windows algorithm modified by Japanese scholar Akhtar, the performance of the presented algorithm can eliminate the impulsive noise effectively and has a better convergence.%  经典的滤波―X最小均方算法(Fx LMS)已经被广泛应用于有源噪声控制(ANC)领域。但是当存在脉冲噪声时,它的性能就会严重退化。基于鲁棒统计的概念介绍了一种新型自适应算法,采用的目标函数为M-估计函数,而不是传统的最小均方误差。该算法分别采用了Huber函数、Hampel三段下降M估计函数等四种不同的M-估计函数作为目标函数,仿真结果表明所采用的算法能有效地消除脉冲噪声,并且与日本学者Akhtar改进的加窗算法相比表现了更好的收敛性。

  15. Influence of perturbative phase noise on active coherent polarization beam combining system.

    Science.gov (United States)

    Ma, Pengfei; Zhou, Pu; Wang, Xiaolin; Ma, Yanxing; Su, Rongtao; Liu, Zejin

    2013-12-02

    In this manuscript, the influence of perturbative phase noise on active coherent polarization beam combining (CPBC) system is studied theoretically and experimentally. By employing a photo-detector to obtain phase error signal for feedback loop, actively coherent polarization beam combining of two 20 W-level single mode polarization-maintained (PM) fiber amplifiers are demonstrated with more than 94% combining efficiency. Then the influence of perturbative phase noise on active CPBC system is illustrated by incorporating a simulated phase noise signal in one of the two amplifiers. Experimental results show that the combining efficiency of the CPBC system is susceptible to the frequency or amplitude of the perturbative phase noise. In order to ensure the combining efficiency of the unit of CPBC system higher than 90%, the competence of our active phase control module for high power operation is discussed, which suggests that it could be worked at 100s W power level. The relationship between residual phase noise of the active controller and the normalized voltage signal of the photo-detector is developed and validated experimentally. Experimental results correspond exactly with the theoretically analyzed combining efficiency. Our method offers a useful approach to estimate the influence of phase noise on CPBC system.

  16. Low Dimensional Methods for Jet Noise Control

    Science.gov (United States)

    2007-11-02

    and is capable of operating in temperatures of up to 26000 F (14500 C) with minimal growth. The pressure drop through a 3.2in. (8.13cm.) substrate...6, 50% to 100% Figure 10. New base SPL conditions with fan blade speeds. MUA unit at 85%, eductor fan on, T~f = 750 In accordance with ISO 3745...heater, control valve). Therefore, we do not anticipate any changes and will not wait for the facility’s ISO validation to continue further with this

  17. Coupled dynamic systems and Le Chatelier's principle in noise control

    Science.gov (United States)

    Maidanik, G.; Becker, K. J.

    2004-05-01

    Investigation of coupling an externally driven dynamic system-a master dynamic system-to a passive one-an adjunct dynamic system-reveals that the response of the adjunct dynamic system affects the precoupled response of the master dynamic system. The responses, in the two dynamic systems when coupled, are estimated by the stored energies (Es) and (E0), respectively. Since the adjunct dynamic system, prior to coupling, was with zero (0) stored energy, E0s=0, the precoupled stored energy (E00) in the master dynamic system is expected to be reduced to (E0) when coupling is instituted; i.e., one expects E0noise control of the master dynamic system would result from the coupling. It is argued that the change in the disposition of the stored energies as just described may not be the only change. The coupling may influence the external input power into the master dynamic system which may interfere with the expected noise control. Indeed, the coupling may influence the external input power such that the expected beneficial noise control may not materialize. Examples of these kinds of noise control reversals are cited.

  18. The Effect of fMRI (Noise) on Cognitive Control

    Science.gov (United States)

    Hommel, Bernhard; Fischer, Rico; Colzato, Lorenza S.; van den Wildenberg, Wery P. M.; Cellini, Cristiano

    2012-01-01

    Stressful situations, the aversiveness of events, or increases in task difficulty (e.g., conflict) have repeatedly been shown to be capable of triggering attentional control adjustments. In the present study we tested whether the particularity of an fMRI testing environment (i.e., EPI noise) might result in such increases of the cognitive control…

  19. Adaptive Feed-Forward Control of Low Frequency Interior Noise

    CERN Document Server

    Kletschkowski, Thomas

    2012-01-01

    This book presents a mechatronic approach to Active Noise Control (ANC). It describes the required elements of system theory, engineering acoustics, electroacoustics and adaptive signal processing in a comprehensive, consistent and systematic manner using a unified notation. Furthermore, it includes a design methodology for ANC-systems, explains its application and describes tools to be used for ANC-system design. From the research point of view, the book presents new approaches to sound source localization in weakly damped interiors. One is based on the inverse finite element method, the other is based on a sound intensity probe with an active free field. Furthermore, a prototype of an ANC-system able to reach the physical limits of local (feed-forward) ANC is described. This is one example for applied research in ANC-system design. Other examples are given for (i) local ANC in a semi-enclosed subspace of an aircraft cargo hold and (ii) for the combination of audio entertainment with ANC.

  20. Global Mode-Based Control of Supersonic Jet Noise

    Science.gov (United States)

    Natarajan, Mahesh; Freund, Jonathan; Bodony, Daniel

    2015-11-01

    The loudest source of high-speed jet noise appears to be describable by unsteady wavepackets that resemble instabilities. We seek to reduce their acoustic impact by developing a novel control strategy that uses global modes to model their dynamics and structural sensitivity of the linearized compressible Navier-Stokes operator to determine effective linear feedback control. Using co-located actuators and sensors we demonstrate the method on an axisymmetric Mach 1.5 fitted with a nozzle. Direct numerical simulations using this control show significant noise reduction, with additional reduction with increase in control gain. Eigenanalysis of the uncontrolled and controlled mean flows reveal fundamental changes in the spectrum at frequencies lower than that used by the control. The non-normality of the global modes is shown to enable this control to affect a wide range of frequencies. The low-frequency wavepacket components are made less acoustically efficient, which is reflected in the far-field noise spectrum. Mean flow alterations are minor near the nozzle and only become apparent further downstream. Office of Naval Research and National Science Foundation.

  1. Anthropogenic noise alters bat activity levels and echolocation calls

    Directory of Open Access Journals (Sweden)

    Jessie P. Bunkley

    2015-01-01

    Full Text Available Negative impacts from anthropogenic noise are well documented for many wildlife taxa. Investigations of the effects of noise on bats however, have not been conducted outside of the laboratory. Bats that hunt arthropods rely on auditory information to forage. Part of this acoustic information can fall within the spectrum of anthropogenic noise, which can potentially interfere with signal reception and processing. Compressor stations associated with natural gas extraction produce broadband noise 24 hours a day, 365 days a year. With over half a million producing gas wells in the U.S. this infrastructure is a major source of noise pollution across the landscape. We conducted a ‘natural experiment’ in the second largest gas extraction field in the U.S. to investigate the potential effects of gas compressor station noise on the activity levels of the local bat assemblage. We used acoustic monitoring to compare the activity level (number of minutes in a night with a bat call of the bat assemblage at sites with compressor stations to sites lacking this infrastructure. We found that activity levels for the Brazilian free-tailed bat (Tadarida brasiliensis were 40% lower at loud compressor sites compared to quieter well pads, whereas the activity levels of four other species (Myotis californicus, M. cillolabrum, M. lucifugus, Parastrellus hesperus were not affected by noise. Furthermore, our results reveal that the assemblage of bat species emitting low frequency (35 kHz echolocation did not exhibit altered activity levels in noise. Lower activity levels of Brazilian free-tailed bats at loud sites indicate a potential reduction in habitat for this species. Additionally, a comparison of echolocation search calls produced by free-tailed bats at sites with and without compressor stations reveal that this species modifies its echolocation search calls in noise—producing longer calls with a narrower bandwidth. Call alterations might affect prey

  2. A Novel Method to Predict Circulation Control Noise

    Science.gov (United States)

    2016-03-17

    dimensional motion of the flow at a moderate Reynolds number. Then , a high Reynolds number flow over a circulation control airfoil is investigated. This...of Sound and Vibration . 200 BAUR, T . & KONGETER, J . 1999 PIV with high temporal resolution for the determina- tion of local pressure reductions ...rotors utilizing circulation control . Journal of Aircraft 20, 946-952. MUNRO, S. E ., AHUJA , K. K. & ENGLAR, R. J . 2001 Noise reduction through

  3. Modeling, analysis, and validation of an active T-shaped noise barrier.

    Science.gov (United States)

    Fan, Rongping; Su, Zhongqing; Cheng, Li

    2013-09-01

    With ever-increasing land traffic, abatement of traffic noise using noise barriers remains significant, yet it is a challenging task due to spatial competition with other infrastructure. In this study, a deep insight into the diffraction characteristics of acoustic fields near noise barriers of various geometries and surface conditions was achieved using numerical simulations. A T-shaped passive noise barrier with acoustically soft upper surfaces was demonstrated to outperform other candidates in a middle- or high-frequency range. Based on attributes of the acoustic field diffracted by T-shaped barriers, an active control strategy was developed to revamp the T-shaped barrier, in which a filtered minimax algorithm was established to drive the secondary sound sources. This algorithm resulted in more uniformly distributed residual sound fields than a filtered-X least mean square algorithm. Performance of the actively controlled barrier was evaluated at different positions and spacings of secondary sound sources and error sensors, leading to a series of optimal criteria for the design of active noise barriers. A prototype was fabricated and validated experimentally, manifesting particular effectiveness in insulating low-frequency noise, supplementing well the capacity of a passive T-shaped barrier which is effective in the middle- or high-frequency range.

  4. NOISE CONTROL IN GAS STATIONS – CASE STUDY

    Directory of Open Access Journals (Sweden)

    Flávio Eduardo Amaral Herzer

    2010-01-01

    Full Text Available The high noise level in urban has changed, in the last decades, in some way of pollution that has worried the health agents. The value registered accused levels of so high discomfort that the urban sound pollution passed to be considered as a kind of pollution that hit the outnumbered people. There are efficient measures in its control, but still there are few companies that adopt measure control and auditive conservation program. This way, the objective of the work was to evaluate the noise level in which the employees and users of the gas station are daily exposed. The survey of quantitative datum was done measuring the noise level right in the emission source and making arithmetic means with the gotten sample. The average obtained revealed that the working environment isn’t appropriate, that means the noise can affect straight to communication and working production. With the prevention objective or stabilizing the auditive lost in witch the workers and the frequenters are submitted to the referred place were proposed measures to the implantation of a Auditive Conservation Program (ACP.

  5. Region-based active contour with noise and shape priors

    CERN Document Server

    Lecellier, François; Fadili, Jalal; Aubert, Gilles; Revenu, Marinette; Saloux, Eric

    2008-01-01

    In this paper, we propose to combine formally noise and shape priors in region-based active contours. On the one hand, we use the general framework of exponential family as a prior model for noise. On the other hand, translation and scale invariant Legendre moments are considered to incorporate the shape prior (e.g. fidelity to a reference shape). The combination of the two prior terms in the active contour functional yields the final evolution equation whose evolution speed is rigorously derived using shape derivative tools. Experimental results on both synthetic images and real life cardiac echography data clearly demonstrate the robustness to initialization and noise, flexibility and large potential applicability of our segmentation algorithm.

  6. Expectation-Based Control of Noise and Chaos

    Science.gov (United States)

    Zak, Michael

    2006-01-01

    A proposed approach to control of noise and chaos in dynamic systems would supplement conventional methods. The approach is based on fictitious forces composed of expectations governed by Fokker-Planck or Liouville equations that describe the evolution of the probability densities of the controlled parameters. These forces would be utilized as feedback control forces that would suppress the undesired diffusion of the controlled parameters. Examples of dynamic systems in which the approach is expected to prove beneficial include spacecraft, electronic systems, and coupled lasers.

  7. Adaptive multichannel control of time-varying broadband noise and vibrations

    NARCIS (Netherlands)

    Berkhoff, A.P.

    2010-01-01

    This paper presents results obtained from a number of applications in which a recent adaptive algorithm for broadband multichannel active noise control is used. The core of the algorithm uses the inverse of the minimum-phase part of the secondary path for improvement of the speed of convergence. A f

  8. Design of Low Noise 16-bit CMOS Digitally Controlled Oscillator

    Directory of Open Access Journals (Sweden)

    Nitin Kumar

    2012-02-01

    Full Text Available In this paper, a new differential delay cell is proposed and 16-bit Digital Controlled Oscillator (DCO based on proposed delay cell is designed. The 16-bit DCO consist of 4-stages differential delay cell in ring structure and a digital control scheme has been used to improved noise characteristics. The structure of the DCO utilizes dual delay path techniques to achieve high oscillation frequency and awide tuning range. The DCO circuit has been simulated in SPICE with 0.5μm technology operating with supply voltage of 5V. DCO achieved a controllable frequency range of [1.7324-4.8649] GHz with a tuningrange of 3.1325GHz (≈64%. The measured output noise is -161.2dB/Hz and the total harmonic distortion have been found 75.4865dB with 6666H control word. The phase noise in proposed DCO design is -179.4dB/Hz at a frequency of 1.7324GHz.

  9. Application of quality control circle activity in reducing the ward noise%品管圈活动在降低血液内科病区噪音中的应用

    Institute of Scientific and Technical Information of China (English)

    林莉; 阮文珍; 丁桂芳

    2014-01-01

    目的:探讨品管圈活动对降低血液内科病区噪音的应用效果。方法成立品管圈活动小组,对病区噪音因素进行分析,制定并采取相应措施。结果病区各种噪声下降率均达80%以上,其中各类车轮产生的噪音下降率达92.31%,家属大声谈话噪音与各仪器报警噪音也分别达88.24%和88.10%。结论品管圈方法的应用降低了病区噪音,患者满意度提高,护理质量提升。%Objective To investigate the QCC activities to reduce the effect of noise on the ward. Methods Formulate and adopt the measures by setting up QQC team to analyze the factors of the ward noise. Results Ward noise reduction rate was more than 80%, including all types of wheel noise reduction rate was up to 92.31%, the family talking loudly and the eachinstrument noise were respectively 88.24% and 88.10%. Conclusion The application of QQC reduces the ward’s noise, improves patient’s satisfaction and nursing quality.

  10. Wideband CMOS low noise amplifier including an active balun

    NARCIS (Netherlands)

    Blaakmeer, S.C.; Klumperink, Eric A.M.; Leenaerts, D.M.W.; Nauta, Bram

    2007-01-01

    An inductorless LNA with active balun is proposed for multi-standard radio applications between 100MHz and 6GHz [1]. It exploits a combination of a common-gate (CG) stage and an common-source (CS) stage with replica biasing to maximize balanced operation, while simultaneously canceling the noise and

  11. BARRIER DESIGN STRATEGIES TO CONTROL NOISE INGRESS INTO DOMESTIC BUILDINGS

    Directory of Open Access Journals (Sweden)

    Christina E. Mediastika

    2003-01-01

    Full Text Available Noise source for buildings adjacent to streets is traffic-generated predominantly. Where people are mostly spend their time indoors, it is important for buildings to have screening or blocking to control noise intrusion into living spaces. But this blocking should also permit airflow. This is important for middle to low-cost domestic buildings, which do not employ conditioned ventilation. A common feature of Indonesian buildings, fence, is studied to perform noise barrier. The fence -a barrier to be- should obey three factors: position, dimension, and material. All these three factors were studied to seek compromised design for acoustic performance and natural ventilation purpose. Domestic building situated in the urban area of Yogyakarta was studying to see the most possible design of the barrier to be. There are two calculation methods employed to investigate the proposed design. The study shows that it is possible to gain minimum of 10 dB noise reduction by placing windows within the shadow effect of approximately 1.5 height fence-barrier.

  12. Current control in inertial Brownian motors by noise recycling

    Science.gov (United States)

    Jia, Zheng-Lin; Li, Kai-Yi; Li, Chun; Yang, Chun-Yan; Mei, Dong-Cheng

    2015-03-01

    The transport properties of an inertial Brownian motor were numerically studied in the presence of recycled noise, which is obtained by re-injecting a fraction of the primary white noise after a processing time, being introduced into the system in a multiplicative way. The simulation results indicate that various parameters such as the external driving force, the friction coefficient, the mass of the particle, the recycling strength, and the delay time can induce the current reversal phenomenon when the sign of the recycling strength is in agreement with the sign of the external bias force, otherwise the current reversal cannot be observed. Additionally, the asymptotic mean velocity as a function of the delay time of the recycled noise always shows a resonance-like behavior with the presence of a maximum current. These results demonstrate that the delay time and the recycling strength of the recycled noise can be used as the feasible and flexible control parameters for the amplitude and direction of the current.

  13. 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.

  14. 一种高阻带余弦调制滤波器组的子带有源噪声控制%Subband active noise control using cosine-modulated filter banks with high-stopband attenuation

    Institute of Scientific and Technical Information of China (English)

    王海燕; 邓洪高; 刘庆华

    2012-01-01

    For wide band active noise control (ANC) system, as a result of the non-ideal characteristic and downsam-pling of the analysis filter banks, the aliasing problem between subband signals in the subband adaptive filter structure is introduced. An interpolated finite impulse response filter (IFIR) is employed to indirectly design the cosine-modulated filter banks prototype filter with high-stopband attenuation to achieve stopband energy minimization, in order to directly eliminate the aliasing problem between subband signals. It has low computational complexity. And compensation the error path delay avoids the delay of cosine-modulated filter banks. Simulation results show that this algorithm has good performance in the broadband gauss white noise and broadband color signal, especially for broadband color signal.%针对宽带有源噪声控制(ANC)系统,在采用子带自适应滤波结构时,由分析滤波器组的非理想特性及下采样原因引起的子带信号混叠问题,采用内插脉冲响应技术问接设计了一种高阻带衰减的低通原型滤波器,使得阻带能量最小化来直接消除子带信号间的混叠问题,具有较低的计算复杂度.同时,通过采用补偿误差通道延迟的方法来消除由分析滤波器组产生的延迟.仿真实验结果表明,该算法在宽带高斯白噪声和宽带有色信号下都具有较好的收敛性能,尤其对宽带有色信号.

  15. Diffusion of Active Particles Subject both to Additive and Multiplicative Noises

    Institute of Scientific and Technical Information of China (English)

    WANG Shao-Hua; YANG Ming; WU Da-Jin

    2011-01-01

    We consider a Langevin equation of active Brownian motion which contains a multiplicative as well as an additive noise term.We study the dependences of the effective diffusion coefficient Deff on both the additive and multiplicative noises.It is found that for fixed small additive noise intensity Deff varies non-monotonously with multiplicative noise intensity, with a minimum at a moderate value of multiplicative noise, and Deff increases monotonously, however, with the multiplicative noise intensity for relatively strong additive noise; for fixed multiplicative noise intensity Deff decreases with growing additive noise intensity until it approaches a constant.An explanation is also given of the different behavior of Deff as additive and multiplicative noises approach infinity,respectively.%@@ We consider a Langevin equation of active Brownian motion which contains a multiplicative as well as an additive noise term.We study the dependences of the effective diffusion coefficient Deff on both the additive and multiplicative noises.It is found that for fixed small additive noise intensity Deff varies non-monotonously with multiplicative noise intensity, with a minimum at a moderate value of multiplicative noise, and Deff increases monotonously, however, with the multiplicative noise intensity for relatively strong additive noise; for fixed multiplicative noise intensity Deff decreases with growing additive noise intensity until it approaches a constant.An explanation is also given of the different behavior of Deff as additive and multiplicative noises approach infinity, respectively.

  16. Noise, Worker Perception, and Worker Concentration in Timber Harvesting Activity

    OpenAIRE

    Efi Yuliati Yovi; Suryaningsih Suryaningsih

    2012-01-01

    Timber harvesting activities are unquestionably related with high risk of work accidents and health disorders.Such activities were not only burdened the workers with heavy physical workloads due to uneasy workingenvironment, and massive work materials and tools, but also physiopsychologically burdened workers as theywere imposed with both mechanical and acoustic vibrations (noise) produced by the chainsaw. However,  it is acommon practice that most of the workers still ignored the importance ...

  17. Pink noise: effect on complexity synchronization of brain activity and sleep consolidation.

    Science.gov (United States)

    Zhou, Junhong; Liu, Dongdong; Li, Xin; Ma, Jing; Zhang, Jue; Fang, Jing

    2012-08-07

    In this study, we hypothesized that steady pink noise is able to change the complexity of brain activities into a characteristic level and it might have significant effect on improving sleep stability. First, we carried out the brain synchronization test in which electroencephalogram (EEG) signals of 6 subjects were recorded. The whole experiment procedure was divided into 5 blocks in the alternative feeding process of 10-min quiet and 10-min noise. After the complexity analysis of fractal dimension, we found that the complexity of the EEG signals decreased with the introduction of the pink noise exposure, showing the brain waves tended to synchronize with the pink noise induction to reach a low level. For the sleep quality experiment, 40 subjects were recruited the group of nocturnal sleep experiment and 10 participants were chosen for nap test. Each subjects slept for two consecutive experimental periods, of which one is pink noise exposed and the other is quiet. For both nocturnal sleep and nap tests, the results in the noise exposure group showed significant enhancement in the percentage of stable sleep time compared to the control group based on the analysis of electrocardiography (ECG) signal with cardiopulmonary coupling approach. This study demonstrates that steady pink noise has significant effect on reducing brain wave complexity and inducing more stable sleep time to improve sleep quality of individuals.

  18. Stochastic resonance in a voltage-controlled MEMS-slider: increasing the signal-to-noise ratio with noise

    NARCIS (Netherlands)

    Droogendijk, H.; de Boer, Meint J.; Brookhuis, Robert Anton; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.

    2013-01-01

    We demonstrate that, using stochastic resonance (SR) in a voltage-controlled MEMS-slider, the signal-to-noise ratio can be increased by adding white noise. Using a Silicon-on-Insulator (SOI) based process, we realised a slider structure with periodic capacitive structures to obtain tunable unstable

  19. The effect of human activity noise on the acoustic quality in open plan office

    DEFF Research Database (Denmark)

    Dehlbæk, Tania Stenholt; Jeong, Cheol-Ho; Brunskog, Jonas

    2016-01-01

    A disadvantage of open plan offices is the noise annoyance. Noise problems in open plan offices have been dealt with in several studies, and standards have been set up. Still, what has not been taken into account is the effect of human activity noise on acoustic conditions. In this study, measure...... D2,S have an impact on the variation in the activity noise. At 1 kHz, the technical background noise influences human activity noise positively. In both octave bands, the human activity noise level varies significantly with the office type, from a call center to a lawyer’s office....

  20. Advance Noise Control Fan II: Test Rig Fan Risk Management Study

    Science.gov (United States)

    Lucero, John

    2013-01-01

    Since 1995 the Advanced Noise Control Fan (ANCF) has significantly contributed to the advancement of the understanding of the physics of fan tonal noise generation. The 9'x15' WT has successfully tested multiple high speed fan designs over the last several decades. This advanced several tone noise reduction concepts to higher TRL and the validation of fan tone noise prediction codes.

  1. Occupational noise management

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-06-15

    Occupational noise is a frequently encountered on-the-job health hazard. This guide presented the responsibilities and regulatory requirements related to business activities where noise above 80 decibels is present. The guide provided a definition of noise and discussed noise hazards, types of noise, and on-the-job noise exposure. A risk assessment to noise in the work environment was also discussed. A guide to a hearing conservation program was also included. The main purpose of a hearing conservation program is the prevention of noise induced hearing loss for employees exposed to occupational noise. The components of such a program were outlined, with particular reference to noise monitoring; noise exposure control; worker education and training; hearing (audiometric) testing; and annual program review and record keeping. It was concluded that in terms of record keeping, it can be very helpful to file noise exposure assessments, particularly personal exposure measurements, with hearing test records to facilitate for future reference. refs., appendices.

  2. Performance of PRD Welled Surfaces in T Shape Noise Barriers for Controlling Environmental Noise

    Directory of Open Access Journals (Sweden)

    S Momen Bellah

    2010-07-01

    Full Text Available "n "n "nBackgrounds and Objectives: There is a considerable notice in the use of noise barriers in recent years. Noise barriers as a control noise solution can increase the insertion loss to protect receivers. This paper presents the results of an investigation about the acoustic efficiency of primitive root sequence diffuser (PRD on environmental single T-shape barrier."nMaterials and Methods: A 2D boundary element method (BEM is used to predict the insertion loss of the tested barriers. The results of rigid and with quadratic residue diffuser (QRD coverage are also predicted for comparison."nResults: It is found that decreasing the design frequency of PRD shifts the frequency effects towards lower frequencies, and therefore the overall A-weighted insertion loss is improved. It is also found that using wire mesh with reasonably efficient resistivity on the top surface of PRD improves the efficiency of the reactive barriers; however utilizing wire meshes with flow resistivity higher than specific acoustic impedance of air on the PRD top of a diffuser barrier significantly reduces the performance of the barrier within the frequency bandwidth of the diffuser. The performance of PRD covered T-shape barrier at 200 Hz was found to be higher than that of its equivalent QRD barriers in both the far field and areas close to the ground. The amount of improvement compared made by PRD barrier compared with its equivalent rigid barrier at far field is about 2 to 3 dB, while this improvement relative to barrier model .QR4. can reach up to 4- 6 dB."nConclusion: Employing PRD on the top surface of T-shape barrier is found to improve the performance of barriers compared with using rigid and QRD coverage at the examined receiver locations.

  3. Evaluation of Noise Control Technology and Alternative Noise Certification Procedures for Propeller-Driven Small Airplanes.

    Science.gov (United States)

    1982-05-01

    Lower Noise Levels for Turboprop Aircraft vs Piston Engine Aircraft. .. .... .... 52 15 Carpet Plots Relating Noise Level, Propeller Diameter...and empiricized the so-called "vortex noise" which occurred at higher frequencies. It was rapidly found that these guidelines were totally inadequate...blade rotational tip Mach number. Various attempts have been made to rationalize the relationships between A- weighted noise level, propeller blade tip

  4. Effect of Acute Noise Exposure on Salivary Cortisol: A Randomized Controlled Trial.

    Science.gov (United States)

    Pouryaghoub, Gholamreza; Mehrdad, Ramin; Valipouri, Alireza

    2016-10-01

    Cardiovascular adverse effects are interesting aspects of occupational noise exposure. One possible mechanism of these effects is an alternation in hypothalamic-pituitary-adrenal axis. Our aim was to measure salivary cortisol response to relatively high-intensity noise exposure in a controlled randomized trial study. We exposed 50 male volunteers to 90 dBA noise for 20 minutes and compared their level of salivary cortisol with 50 non-exposed controls. Salivary samples obtained before and after exposure. Before intervention means (SD) salivary cortisol level were 3.24 (0.47)ng/ml and 3.25 (0.41)ng/ml for exposed and non-exposed groups respectively. Mean salivary cortisol level increased to 4.17 ng/mlafter intervention in exposure group. This increment was statistically significant (P=0.00). Mean salivary cortisol level of the non-exposed group had statistically non-significant decrement after this period (0.2 ng/ml). The difference between salivary cortisol level of non-exposed and exposed groups after the intervention was statistically significant. Noise exposure may affect the hypothalamic-pituitary-adrenal axis activity, and this may be one of the mechanisms of noise exposure cardiovascular effects.

  5. Optimal periodic disturbance reduction for active noise cancelation

    Science.gov (United States)

    Kinney, C. E.; de Callafon, R. A.; Dunens, E.; Bargerhuff, R.; Bash, C. E.

    2007-08-01

    The design of an optimal internal model-based (IMB) controller by extending standard discrete time optimal control theory for IMB controllers is described. The optimal observer and state feedback gains of the IMB controller are given via the solution of discrete time algebraic Riccati equations. The design method is applied to an acoustic system that is subjected to disturbances from a server fan. Periodic disturbances from the server fan appear as harmonics of the fundamental frequency of the fan. Parametric models for the plant and non-periodic part of the disturbance are identified from experimental data. An internal model is designed in discrete time and the internal model principle is used to design a feedback controller that rejects periodic disturbances in the acoustic system. The controller is implemented in real-time and successfully attenuates the first four harmonics of the fan noise.

  6. Control of noise and structural vibration a MATLAB-based approach

    CERN Document Server

    Mao, Qibo

    2013-01-01

    Control of Noise and Structural Vibration presents a MATLAB®-based approach to solving the problems of undesirable noise generation and transmission by structures and of undesirable vibration within structures in response to environmental or operational forces. The fundamentals of acoustics, vibration and coupling between vibrating structures and the sound fields they generate are introduced including a discussion of the finite element method for vibration analysis. Following this, the treatment of sound and vibration control begins, illustrated by example systems such as beams, plates and double plate structures. Sensor and actuator placement is explained as is the idea of modal sensor–actuators. The design of appropriate feedback systems includes consideration of basic stability criteria and robust active structural acoustic control. Single and multi-mode positive position feedback (PPF) control systems are also described in the context of loudspeaker–duct model with non-collocated loudspeaker–microp...

  7. Vortex shedding noise control in idling circular saws using air ejection at the teeth

    Science.gov (United States)

    Yanagimoto, K.; Mote, C. D.; Ichimiya, R.

    1994-04-01

    Aerodynamically induced noise from an idling circular saw can be very intense. The purpose of the present investigation is noise reduction through vortex shedding control in idling circular saws. Reduction of aerodynamic noise in idling circular saws may be possible by controlling the shed vortices and flow structures in the space between teeth, based on the earlier observations.

  8. Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

    Science.gov (United States)

    Ho, Jen-Hsuan; Berkhoff, Arthur

    2014-03-01

    This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of two panels with air in between and offers the advantages of low sound transmission at high frequencies, low heat transmission, and low weight. The double panel structure is widely used, such as in the aerospace and automotive industries. Nevertheless, the resonance of the cavity and the poor sound transmission loss at low frequencies limit the double panel's noise control performance. Applying active structural acoustic control to the panels or active noise control to the cavity has been discussed in many papers. In this paper, the resonances of the panels and the cavity are considered simultaneously to further reduce the transmitted noise through an existing double panel structure. A structural-acoustic coupled model is developed to investigate and compare various structural control and cavity control methods. Numerical analysis and real-time control results show that structural control should be applied to both panels. Three types of cavity control sources are presented and compared. The results indicate that the largest noise reduction is obtained with cavity control by loudspeakers modified to operate as incident pressure sources.

  9. Cooperating or Fighting with Control Noise in the Optimal Manipulation of Quantum Dynamics

    CERN Document Server

    Shuang, F; Shuang, Feng; Rabitz, Herschel

    2004-01-01

    This paper investigates the impact of control field noise on the optimal manipulation of quantum dynamics. Simulations are performed on several multilevel quantum systems with the goal of population transfer in the presence of significant control noise. The noise enters as run-to-run variations in the control amplitude and phase with the observation being an ensemble average over many runs as is commonly done in the laboratory. A genetic algorithm with an improved elitism operator is used to find the optimal field that either fights against or cooperates with control field noise. When seeking a high control yield it is possible to find fields that successfully fight with the noise while attaining good quality stable results. When seeking modest control yields, fields can be found which are optimally shaped to cooperate with the noise and thereby drive the dynamics more efficiently. In general, noise reduces the coherence of the dynamics, but the results indicate that population transfer objectives can be met ...

  10. 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.

  11. Effect of Poisson noise on adiabatic quantum control

    Science.gov (United States)

    Kiely, A.; Muga, J. G.; Ruschhaupt, A.

    2017-01-01

    We present a detailed derivation of the master equation describing a general time-dependent quantum system with classical Poisson white noise and outline its various properties. We discuss the limiting cases of Poisson white noise and provide approximations for the different noise strength regimes. We show that using the eigenstates of the noise superoperator as a basis can be a useful way of expressing the master equation. Using this, we simulate various settings to illustrate different effects of Poisson noise. In particular, we show a dip in the fidelity as a function of noise strength where high fidelity can occur in the strong-noise regime for some cases. We also investigate recent claims [J. Jing et al., Phys. Rev. A 89, 032110 (2014), 10.1103/PhysRevA.89.032110] that this type of noise may improve rather than destroy adiabaticity.

  12. Noise controlled pattern for- mation in subexcitable media

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The numerical simulation on a reaction-diffu- sion system indicates that different patterns can be obtained by tuning the strength of parameter noise in subexcitable media. With the increase of noise intensity, the waves sustained by noise are not broken up as usual, they evolve orderly, and the period of the waves decreases, the survival time of waves varies. The time interval of inputting noise also influences the process of pattern formation and the survival time of waves.

  13. Multiobjective Output Feedback Control of a Class of Stochastic Hybrid Systems with State-Dependent Noise

    Directory of Open Access Journals (Sweden)

    S. Aberkane

    2007-01-01

    Full Text Available This paper deals with dynamic output feedback control of continuous-time active fault tolerant control systems with Markovian parameters (AFTCSMP and state-dependent noise. The main contribution is to formulate conditions for multiperformance design, related to this class of stochastic hybrid systems, that take into account the problematic resulting from the fact that the controller only depends on the fault detection and isolation (FDI process. The specifications and objectives under consideration include stochastic stability, ℋ2 and ℋ∞ (or more generally, stochastic integral quadratic constraints performances. Results are formulated as matrix inequalities. The theoretical results are illustrated using a classical example from literature.

  14. 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

  15. A study of the prediction of cruise noise and laminar flow control noise criteria for subsonic air transports

    Science.gov (United States)

    Swift, G.; Mungur, P.

    1979-01-01

    General procedures for the prediction of component noise levels incident upon airframe surfaces during cruise are developed. Contributing noise sources are those associated with the propulsion system, the airframe and the laminar flow control (LFC) system. Transformation procedures from the best prediction base of each noise source to the transonic cruise condition are established. Two approaches to LFC/acoustic criteria are developed. The first is a semi-empirical extension of the X-21 LFC/acoustic criteria to include sensitivity to the spectrum and directionality of the sound field. In the second, the more fundamental problem of how sound excites boundary layer disturbances is analyzed by deriving and solving an inhomogeneous Orr-Sommerfeld equation in which the source terms are proportional to the production and dissipation of sound induced fluctuating vorticity. Numerical solutions are obtained and compared with corresponding measurements. Recommendations are made to improve and validate both the cruise noise prediction methods and the LFC/acoustic criteria.

  16. CONTROLLING RISK DUE TO NOISE ON FERRY BOAT

    Directory of Open Access Journals (Sweden)

    Aleksandar Nikolic

    2013-07-01

    Full Text Available Environmental and occupational noise is common nuisance that affects the health of employees. Performed health checks of employees engaged by Company “Pomorski Saobraćaj” showed that 5% of examined sailors had hearing loss. The results were a trigger for starting experiment on noise risk assessment with objective to discover possibilities of noise pollution presence, precise significant noise sources and describe solutions for eliminating negative effects. Several measurements on five positions were performed on ferry boat “KAMENARI”, according to EC Physical Agents Directive and Merchant Shipping and Fishing Vessels Regulations 2007. Noise on selected positions exceeded the limit for about 1-5dB. Noise exposure level was 84.5dB. Diesel engine, exhaust system and structural noise were main sources of excessive noise. Experiment shows noise presence as nuisance that affects sailors. Noise presents a serious threat for sailor’s health. It interferes with crew communication and jeopardizes navigation safety. Technical measures, crew health checks and noise monitoring could prevent all negative effects.

  17. Subjective annoyance caused by indoor low-level and low frequency noise and control method

    Institute of Scientific and Technical Information of China (English)

    DI Guo-qing; ZHANG Bang-jun; SHANG Qi

    2005-01-01

    The influence of low-level noise has not been widely noticed. This paper discovered that low-level and low frequency noise(Aweighted equivalent level Leq < 45 dB) causes higher probability of subjective annoyance. The fuzzy mathematic principle was applied to deal with the threshold level of subjective annoyance from noise in this study; there is preferable relationship between the indoor noise and noise annoyance at low frequency noise level. Study indicated at the same centered noise level, the change of annoyance probability is mainly caused by the change of the frequency spectrum characteristic of the indoor noise. Under low noise level environment, without change of the medium-low frequency noise, the slight increase of medium-high frequency noise level with the help of noise sheltering effect can significantly reduce the noise annoyance. This discovery brings a new resolution on how to improve the environmental quality of working or living places. A noise control model is given in this study according to the acoustic analysis.

  18. The Effect of Non-Harmonic Active Twist Actuation on BVI Noise

    Science.gov (United States)

    Fogarty, David E.; Wilbur, Matthew L.; Sekula, Martin K.

    2011-01-01

    The results of a computational study examining the effects of non-harmonic active-twist control on blade-vortex interaction (BVI) noise for the Apache Active Twist Rotor are presented. Rotor aeroelastic behavior was modeled using the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics code and the rotor noise was predicted using the acoustics code PSU-WOPWOP. The application of non-harmonic active-twist inputs to the main rotor blade system comprised three parameters: azimuthal location to start actuation, azimuthal duration of actuation, and magnitude of actuation. The acoustic analysis was conducted for a single low-speed flight condition of advance ratio mu=0.14 and shaft angle-of-attack, a(sub s)=+6deg. BVI noise levels were predicted on a flat plane of observers located 1.1 rotor diameters beneath the rotor. The results indicate significant reductions of up to 10dB in BVI noise using a starting azimuthal location for actuation of 90?, an azimuthal duration of actuation of 90deg, and an actuation magnitude of +1.5 ft-lb.

  19. Danish activities concerning noise in the environment (A)

    DEFF Research Database (Denmark)

    Ingerslev, Fritz

    1982-01-01

    the country in international collaboration. It is claimed that noise abatement will be diffuse and weak, if it is not based on a national strategy. The discussion of noise in the environment covers: external industrial noise, road traffic noise, and air traffic noise. The principles on which the maximum....... The regulations concerning road traffic noise are based on results of extensive interviews of persons living in areas with various exposure levels. The results of these interviews will be reported as well as the conclusions drawn....

  20. What kind of noise is brain noise? Anomalous scaling behavior of the resting brain activity fluctuations.

    Directory of Open Access Journals (Sweden)

    Daniel eFraiman

    2012-07-01

    Full Text Available The study of spontaneous fluctuations of brain activity, often referred as brain noise, is getting increasing attention in functional magnetic resonance imaging (fMRI studies. Despite important efforts, much of the statistical properties of such fluctuations remain largely unknown. This work scrutinize these fluctuations looking at specific statistical properties which are relevant to clarify its dynamical origins. Here, three statistical features which clearly differentiate brain data from naive expectations for random processes are uncovered: First, the variance of the fMRI mean signal as a function of the number of averaged voxels remains constant across a wide range of observed clusters sizes. Second, the anomalous behavior of the variance is originated by bursts of synchronized activity across regions, regardless of their widely different sizes. Finally, the correlation length (i.e., the length at which the correlation strength between two regions vanishes as well as mutual information diverges with the cluster's size considered, such that arbitrarily large clusters exhibit the same collective dynamics than smaller ones. These three properties are known to be exclusive of complex systems exhibiting critical dynamics, where the spatio-temporal dynamics show these peculiar type of fluctuations. Thus, these findings are fully consistent with previous reports of brain critical dynamics, and are relevant for the interpretation of the role of fluctuations and variability in brain function in health and disease.

  1. Efficient Control of Nonlinear Noise-Corrupted Systems Using a Novel Model Predictive Control Framework

    OpenAIRE

    Weissel, Florian; Huber, Marco F.; Hanebeck, Uwe D.

    2007-01-01

    Model identification and measurement acquisition is always to some degree uncertain. Therefore, a framework for Nonlinear Model Predictive Control (NMPC) is proposed that explicitly considers the noise influence on nonlinear dynamic systems with continuous state spaces and a finite set of control inputs in order to significantly increase the control quality. Integral parts of NMPC are the prediction of system states over a finite horizon as well as the problem specific modeling of reward func...

  2. Using active resonator impedance matching for shot-noise limited, cavity enhanced amplitude modulated laser absorption spectroscopy.

    Science.gov (United States)

    Chow, Jong H; Littler, Ian C M; Rabeling, David S; McClelland, David E; Gray, Malcolm B

    2008-05-26

    We introduce a closed-loop feedback technique to actively control the coupling condition of an optical cavity, by employing amplitude modulation of the interrogating laser. We show that active impedance matching of the cavity facilitates optimal shot-noise sensing performance in a cavity enhanced system, while its control error signal can be used for intra-cavity absorption or loss signal extraction. We present the first demonstration of this technique with a fiber ring cavity, and achieved shot-noise limited loss sensitivity. We also briefly discuss further use of impedance matching control as a tool for other applications.

  3. Experimental validation of tonal noise control from subsonic axial fans using flow control obstructions

    Science.gov (United States)

    Gérard, Anthony; Berry, Alain; Masson, Patrice; Gervais, Yves

    2009-03-01

    This paper presents the acoustic performance of a novel approach for the passive adaptive control of tonal noise radiated from subsonic fans. Tonal noise originates from non-uniform flow that causes circumferentially varying blade forces and gives rise to a considerably larger radiated dipolar sound at the blade passage frequency (BPF) and its harmonics compared to the tonal noise generated by a uniform flow. The approach presented in this paper uses obstructions in the flow to destructively interfere with the primary tonal noise arising from various flow conditions. The acoustic radiation of the obstructions is first demonstrated experimentally. Indirect on-axis acoustic measurements are used to validate the analytical prediction of the circumferential spectrum of the blade unsteady lift and related indicators generated by the trapezoidal and sinusoidal obstructions presented in Ref. [A. Gérard, A. Berry, P. Masson, Y. Gervais, Modelling of tonal noise control from subsonic axial fans using flow control obstructions, Journal of Sound and Vibration (2008), this issue, doi: 10.1016/j.jsv.2008.09.027.] and also by cylindrical obstructions used in the literature. The directivity and sound power attenuation are then given in free field for the control of the BPF tone generated by rotor/outlet guide vane (OGV) interaction and the control of an amplified BPF tone generated by the rotor/OGV interaction with an added triangular obstruction between two outlet guide vanes to enhance the primary non-uniform flow. Global control was demonstrated in free field, attenuation up to 8.4 dB of the acoustic power at BPF has been measured. Finally, the aerodynamic performances of the automotive fan used in this study are almost not affected by the presence of the control obstruction.

  4. Foundations for Cooperating with Control Noise in the Manipulation of Quantum Dynamics

    CERN Document Server

    Shuang, F; Rabitz, H; Dykman, Mark; Rabitz, Herschel; Shuang, Feng

    2006-01-01

    This paper develops the theoretical foundations for the ability of a control field to cooperate with noise in the manipulation of quantum dynamics. The noise enters as run-to-run variations in the control amplitudes, phases and frequencies with the observation being an ensemble average over many runs as is commonly done in the laboratory. Weak field perturbation theory is developed to show that noise in the amplitude and frequency components of the control field can enhance the process of population transfer in a multilevel ladder system. The analytical results in this paper support the point that under suitable conditions an optimal field can cooperate with noise to improve the control outcome.

  5. Active noise canceling system for mechanically cooled germanium radiation detectors

    Science.gov (United States)

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  6. Arecoline cannot alter testicular dysfunction and pineal activation caused by noise in wistar rat.

    Science.gov (United States)

    Saha, Indraneel; Chatterjee, Aniruddha; Chatterji, Urmi; Maiti, B R

    2017-07-13

    Millions of people consume betel nut for increased capacity to work and for stress reduction. The nut contains arecoline, which has multiple side effects on endocrine functions. Objective of the work is to investigate pineal-testicular responses to noise and after arecoline treatment in noise in rats. Noise exposure (100 dB, 6 h daily, 10 days) caused pineal stimulation ultrastructurally and at indoleamines level. Leydig cell dysfunction with fall of testosterone level and suppression of sex accessories were noticed. In contrast, pineal activity was inhibited and reproductive functions were stimulated after arecoline administration, confirmed from reversed changes to those of noise. Arecoline treatment in noise exposure showed same results as in noise both in pineal and in reproductive functions. It is concluded that noise causes testicular dysfunction probably by gonadotropin suppression induced by pineal melatonin in noise. Furthermore, arecoline cannot prevent it in noise in rats.

  7. Synchronization for unified chaotic systems with noise-disturbed parameters by sliding mode control

    Institute of Scientific and Technical Information of China (English)

    HEN Yuan; ZHANG Qun-jiao

    2008-01-01

    In this paper,the active sliding mode control method is utilized to study the synchronization for unified chaotic systems with noise-disturbed parameters.Some novet results about the suitable sliding mode surface and the synchronizing control law are derived,which avoid the mistake inequality sC△Ae≤‖△A‖∞ sCe in Ref.[Chaos,Solitons & Fractals 21(2004) 1249].Finally,numerical sireulations are included to show the correctness of our results and the effectiveness of the developed approach.

  8. Structural control on the directional amplification of seismic noise (Campo Imperatore, central Italy)

    Science.gov (United States)

    Pischiutta, M.; Fondriest, M.; Demurtas, M.; Magnoni, F.; Di Toro, G.; Rovelli, A.

    2017-08-01

    Seismic signals propagating across a fault may yield information on the internal structure of the fault zone. Here we have assessed the amplification of seismic noise (i.e., ambient vibrations generated by natural or anthropogenic disturbances) across the Vado di Corno Fault (Campo Imperatore, central Italy). The fault zone is considered as an exhumed analogue of the normal faults activated during the L'Aquila 2009 earthquake sequence. Detailed structural geological survey of the footwall block revealed that the fault zone is highly anisotropic and is affected by a complex network of faults and fractures with dominant WNW-ESE strike. We measured seismic noise with portable seismometers along a ∼500 m long transect perpendicular to the average fault strike. Seismic signals were processed calculating the horizontal-to-vertical spectral ratios and performing wavefield polarization analyses. We found a predominant NE-SW to NNE-SSW (i.e., ca. perpendicular to the average strike of the fault-fracture network) amplification of the horizontal component of the seismic waves. Numerical simulations of earthquake-induced ground motions ruled out the role of topography in controlling the polarization and the amplitude of the waves. Therefore, the higher seismic noise amplitude observed in the fault-perpendicular direction was related to the measured fracture network and the resulting stiffness anisotropy of the rock mass. These observations open new perspectives in using measures of ambient seismic noise, which are fast and inexpensive, to estimate the dominant orientation of fracture networks within fault zones.

  9. Improper activation of D1 and D2 receptors leads to excess noise in prefrontal cortex

    Science.gov (United States)

    Avery, Michael C.; Krichmar, Jeffrey L.

    2015-01-01

    The dopaminergic system has been shown to control the amount of noise in the prefrontal cortex (PFC) and likely plays an important role in working memory and the pathophysiology of schizophrenia. We developed a model that takes into account the known receptor distributions of D1 and D2 receptors, the changes these receptors have on neuron response properties, as well as identified circuitry involved in working memory. Our model suggests that D1 receptor under-stimulation in supragranular layers gates internal noise into the PFC leading to cognitive symptoms as has been proposed in attention disorders, while D2 over-stimulation gates noise into the PFC by over-activation of cortico-striatal projecting neurons in infragranular layers. We apply this model in the context of a memory-guided saccade paradigm and show deficits similar to those observed in schizophrenic patients. We also show set-shifting impairments similar to those observed in rodents with D1 and D2 receptor manipulations. We discuss how the introduction of noise through changes in D1 and D2 receptor activation may account for many of the symptoms of schizophrenia depending on where this dysfunction occurs in the PFC. PMID:25814948

  10. Improper activation of D1 and D2 receptors leads to excess noise in prefrontal cortex

    Directory of Open Access Journals (Sweden)

    Michael eAvery

    2015-03-01

    Full Text Available The dopaminergic system has been shown to control the amount of noise in the prefrontal cortex (PFC and likely plays an important role in working memory and the pathophysiology of schizophrenia. We developed a model that takes into account the known receptor distributions of D1 and D2 receptors, the changes these receptors have on neuron response properties, as well as identified circuitry involved in working memory. Our model suggests that D1 receptor under-stimulation in supragranular layers gates internal noise into the PFC leading to cognitive symptoms as has been proposed in attention disorders, while D2 over-stimulation gates noise into the PFC by over-activation of cortico-striatal projecting neurons in infragranular layers. We apply this model in the context of a memory-guided saccade paradigm and show deficits similar to those observed in schizophrenic patients. We also show set-shifting impairments similar to those observed in rodents with D1 and D2 receptor manipulations. We discuss how the introduction of noise through changes in D1 and D2 receptor activation may account for many of the symptoms of schizophrenia depending on where this dysfunction occurs in the PFC.

  11. 'NASA Invention of the Year' Controls Noise and Vibration

    Science.gov (United States)

    2007-01-01

    Developed at NASA's Langley Research Center, the Macro-Fiber Composite (MFC) is designed to control vibration, noise, and deflections in composite structural beams and panels. Smart Material Corporation specializes in the development of piezocomposite components, and licensed the MFC technology from Langley in 2002. To date, Smart Material Corporation has sold MFCs to over 120 customers, including such industry giants as Volkswagen, Toyota, Honda, BMW, General Electric, and the tennis company, HEAD. The company estimates that its customers have filed at least 100 patents for their various unique uses of the technology. In addition, the company's product portfolio has grown to include piezoceramic fibers and fiber composites, piezoceramic actuators and sensors, and test equipment for these products. It also offers a compact, lightweight power system for MFC testing and validation. Consumer applications already on the market include piezoelectric systems as part of audio speakers, phonograph cartridges and microphones, and recreational products requiring vibration control, such as skis, snowboards, baseball bats, hockey sticks, and tennis racquets.

  12. Electric motor noise control over the past ten years

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, J.D. (Bolt Beranek and Newman Inc., Cambridge, MA); Bruce, R.D.

    1982-01-01

    Electric motors have been recognized as a source of noise and vibration requiring solutions for almost 40 years. Noise from electric motors is not as major a source of concern today as it was 10 years ago. In this paper, the authors attempt to summarize very briefly why quiet motors are available today.

  13. Low-noise encoding of active touch by layer 4 in the somatosensory cortex.

    Science.gov (United States)

    Hires, Samuel Andrew; Gutnisky, Diego A; Yu, Jianing; O'Connor, Daniel H; Svoboda, Karel

    2015-08-06

    Cortical spike trains often appear noisy, with the timing and number of spikes varying across repetitions of stimuli. Spiking variability can arise from internal (behavioral state, unreliable neurons, or chaotic dynamics in neural circuits) and external (uncontrolled behavior or sensory stimuli) sources. The amount of irreducible internal noise in spike trains, an important constraint on models of cortical networks, has been difficult to estimate, since behavior and brain state must be precisely controlled or tracked. We recorded from excitatory barrel cortex neurons in layer 4 during active behavior, where mice control tactile input through learned whisker movements. Touch was the dominant sensorimotor feature, with >70% spikes occurring in millisecond timescale epochs after touch onset. The variance of touch responses was smaller than expected from Poisson processes, often reaching the theoretical minimum. Layer 4 spike trains thus reflect the millisecond-timescale structure of tactile input with little noise.

  14. Industrial Noise Pollution and the Need for Applying Protocols for its Control and Decrease

    Directory of Open Access Journals (Sweden)

    Parvin Nasiri

    1999-03-01

    Full Text Available Industrialization has had many complications for human beings and has been a threat to social mental and physical health. Vibration induced noises in the workplace is one of the main devastating factor in producing hearing loss in workers. Recently, several investigations on the issue of noise pollution and noise dosimetry and also Noise induced hearing loss have been developed. In the current article we will have a look and sometimes reconsideration on the results and of these studies and will discuss the findings in regard to noise control and management in details.

  15. A study of poultry processing plant noise characteristics and potential noise control techniques

    Science.gov (United States)

    Wyvill, J. C.; Jape, A. D.; Moriarity, L. J.; Atkins, R. D.

    1980-01-01

    The noise environment in a typical poultry processing plant was characterized by developing noise contours for two representative plants: Central Soya of Athens, Inc., Athens, Georgia, and Tip Top Poultry, Inc., Marietta, Georgia. Contour information was restricted to the evisceration are of both plants because nearly 60 percent of all process employees are stationed in this area during a normal work shift. Both plant evisceration areas were composed of tile walls, sheet metal ceilings, and concrete floors. Processing was performed in an assembly-line fashion in which the birds travel through the area on overhead shackles while personnel remain at fixed stations. Processing machinery was present throughout the area. In general, the poultry processing noise problem is the result of loud sources and reflective surfaces. Within the evisceration area, it can be concluded that only a few major sources (lung guns, a chiller component, and hock cutters) are responsible for essentially all direct and reverberant sound pressure levels currently observed during normal operations. Consequently, any effort to reduce the noise problem must first address the sound power output of these sources and/or the absorptive qualitities of the room.

  16. Experimental Study of Active Techniques for Blade/Vortex Interaction Noise Reduction

    Science.gov (United States)

    Kobiki, Noboru; Murashige, Atsushi; Tsuchihashi, Akihiko; Yamakawa, Eiichi

    This paper presents the experimental results of the effect of Higher Harmonic Control (HHC) and Active Flap on the Blade/Vortex Interaction (BVI) noise. Wind tunnel tests were performed with a 1-bladed rotor system to evaluate the simplified BVI phenomenon avoiding the complicated aerodynamic interference which is characteristically and inevitably caused by a multi-bladed rotor. Another merit to use this 1-bladed rotor system is that the several objective active techniques can be evaluated under the same condition installed in the same rotor system. The effects of the active techniques on the BVI noise reduction were evaluated comprehensively by the sound pressure, the blade/vortex miss distance obtained by Laser light Sheet (LLS), the blade surface pressure distribution and the tip vortex structure by Particle Image Velocimetry (PIV). The correlation among these quantities to describe the effect of the active techniques on the BVI conditions is well obtained. The experiments show that the blade/vortex miss distance is more dominant for BVI noise than the other two BVI governing factors, such as blade lift and vortex strength at the moment of BVI.

  17. Dopamine Activation Preserves Visual Motion Perception Despite Noise Interference of Human V5/MT

    Science.gov (United States)

    Yousif, Nada; Fu, Richard Z.; Abou-El-Ela Bourquin, Bilal; Bhrugubanda, Vamsee; Schultz, Simon R.

    2016-01-01

    When processing sensory signals, the brain must account for noise, both noise in the stimulus and that arising from within its own neuronal circuitry. Dopamine receptor activation is known to enhance both visual cortical signal-to-noise-ratio (SNR) and visual perceptual performance; however, it is unknown whether these two dopamine-mediated phenomena are linked. To assess this, we used single-pulse transcranial magnetic stimulation (TMS) applied to visual cortical area V5/MT to reduce the SNR focally and thus disrupt visual motion discrimination performance to visual targets located in the same retinotopic space. The hypothesis that dopamine receptor activation enhances perceptual performance by improving cortical SNR predicts that dopamine activation should antagonize TMS disruption of visual perception. We assessed this hypothesis via a double-blinded, placebo-controlled study with the dopamine receptor agonists cabergoline (a D2 agonist) and pergolide (a D1/D2 agonist) administered in separate sessions (separated by 2 weeks) in 12 healthy volunteers in a William's balance-order design. TMS degraded visual motion perception when the evoked phosphene and the visual stimulus overlapped in time and space in the placebo and cabergoline conditions, but not in the pergolide condition. This suggests that dopamine D1 or combined D1 and D2 receptor activation enhances cortical SNR to boost perceptual performance. That local visual cortical excitability was unchanged across drug conditions suggests the involvement of long-range intracortical interactions in this D1 effect. Because increased internal noise (and thus lower SNR) can impair visual perceptual learning, improving visual cortical SNR via D1/D2 agonist therapy may be useful in boosting rehabilitation programs involving visual perceptual training. SIGNIFICANCE STATEMENT In this study, we address the issue of whether dopamine activation improves visual perception despite increasing sensory noise in the visual cortex

  18. Synchronization of noise-perturbed generalized Lorenz system by sliding mode control*

    Institute of Scientific and Technical Information of China (English)

    Kong Cui-Cui; Chen Shi-Hua

    2009-01-01

    Synchronization of a noise-perturbed generalized Lorenz system by using sliding mode control method is investigated in this paper. Two sliding mode control methods are proposed to synchronize the noise-perturbed generalized Lorenz system. Numerical simulations are also provided for the illustration and verification of the methods.

  19. Use of a beat effect for the automatic positioning of flow obstructions to control tonal fan noise: Theory and experiments

    Science.gov (United States)

    Gérard, A.; Berry, A.; Masson, P.; Moreau, S.

    2013-09-01

    Tonal noise generated by axial fans at the Blade Passage Frequency and its harmonics is a source of discomfort for low-speed fans used in many cooling and ventilation applications. The noise control approach presented here is based on the interference between the unsteady aerodynamic blade loads responsible for tonal noise generation and secondary aerodynamic loads generated in the rotor plane by fixed, carefully positioned, small obstructions in the upstream flow. Although not strictly active control, the magnitude and phase of the secondary tonal noise can be adjusted by varying the axial distance between the rotor and the obstruction, and the circumferential position of the obstruction, respectively. An optimal position of the obstruction generally exists, that minimizes the total noise at a given frequency. This paper establishes a practical method for automatic positioning of such control obstructions. In a first step, the method searches for the optimal axial distance between the rotor and the obstruction using a slowly rotating control obstruction. The modulation created by the rotation of the obstruction allows for the primary and secondary noises to be distinguished in the frequency response of the sound field. The steepest descent algorithm is used to find the optimal axial distance, for which the magnitudes of the primary and secondary tonal noise are equal at the error microphone. Then, the optimal angular position of the obstruction is obtained by slowly rotating the obstruction until minimal total noise is achieved. Finally, it is shown that at the optimal axial and angular position, the BPF tone, which produced the largest area in the loudness pattern, has been greatly reduced.

  20. Noise Temperature Characteristics and Gain-control of Avalanche Photodiodes for Laser Radar

    Institute of Scientific and Technical Information of China (English)

    CAI Xi-ping; SHANG Hong-Bo; BAI Ji-yuan; YANG Shuang; WANG Li-na

    2008-01-01

    Avalanche photodiodes(APDs) are promising light sensors with high quantum efficiency and low noise. It has been extensively used in radiation detection, laser radar and other weak signal detection fields. Unlike other photodiodes, APD is a very sensitive light detector with very high internal gain. The basic theory shows that the gain of APD is related to the temperature. The internal gain fluctuates with the variation of temperature. Investigated was the influence of the variation of the gain induced by the fluctuation of temperature on the output from APD for a very weak laser pulse input in laser radar. An active reverse-biased voltage compensation method is used to stabilize the gain of APD. An APD model is setup to simulate the detection of light pulse signal. The avalanche process, various noises and temperature's effect are all included in the model. Our results show that for the detection of weak light signal such as in laser radar, even a very small fluctuation of temperature could cause a great effect on APD's gain. The results show that the signal-to-noise ratio of the APD's output could be improved effectively with the active gain-control system.

  1. Automatic exposure control systems designed to maintain constant image noise: effects on computed tomography dose and noise relative to clinically accepted technique charts.

    Science.gov (United States)

    Favazza, Christopher P; Yu, Lifeng; Leng, Shuai; Kofler, James M; McCollough, Cynthia H

    2015-01-01

    To compare computed tomography dose and noise arising from use of an automatic exposure control (AEC) system designed to maintain constant image noise as patient size varies with clinically accepted technique charts and AEC systems designed to vary image noise. A model was developed to describe tube current modulation as a function of patient thickness. Relative dose and noise values were calculated as patient width varied for AEC settings designed to yield constant or variable noise levels and were compared to empirically derived values used by our clinical practice. Phantom experiments were performed in which tube current was measured as a function of thickness using a constant-noise-based AEC system and the results were compared with clinical technique charts. For 12-, 20-, 28-, 44-, and 50-cm patient widths, the requirement of constant noise across patient size yielded relative doses of 5%, 14%, 38%, 260%, and 549% and relative noises of 435%, 267%, 163%, 61%, and 42%, respectively, as compared with our clinically used technique chart settings at each respective width. Experimental measurements showed that a constant noise-based AEC system yielded 175% relative noise for a 30-cm phantom and 206% relative dose for a 40-cm phantom compared with our clinical technique chart. Automatic exposure control systems that prescribe constant noise as patient size varies can yield excessive noise in small patients and excessive dose in obese patients compared with clinically accepted technique charts. Use of noise-level technique charts and tube current limits can mitigate these effects.

  2. Jet Engine Noise Generation, Prediction and Control. Chapter 86

    Science.gov (United States)

    Huff, Dennis L.; Envia, Edmane

    2004-01-01

    Aircraft noise has been a problem near airports for many years. It is a quality of life issue that impacts millions of people around the world. Solving this problem has been the principal goal of noise reduction research that began when commercial jet travel became a reality. While progress has been made in reducing both airframe and engine noise, historically, most of the aircraft noise reduction efforts have concentrated on the engines. This was most evident during the 1950 s and 1960 s when turbojet engines were in wide use. This type of engine produces high velocity hot exhaust jets during takeoff generating a great deal of noise. While there are fewer commercial aircraft flying today with turbojet engines, supersonic aircraft including high performance military aircraft use engines with similar exhaust flow characteristics. The Pratt & Whitney F100-PW-229, pictured in Figure la, is an example of an engine that powers the F-15 and F-16 fighter jets. The turbofan engine was developed for subsonic transports, which in addition to better fuel efficiency also helped mitigate engine noise by reducing the jet exhaust velocity. These engines were introduced in the late 1960 s and power most of the commercial fleet today. Over the years, the bypass ratio (that is the ratio of the mass flow through the fan bypass duct to the mass flow through the engine core) has increased to values approaching 9 for modern turbofans such as the General Electric s GE-90 engine (Figure lb). The benefits to noise reduction for high bypass ratio (HPBR) engines are derived from lowering the core jet velocity and temperature, and lowering the tip speed and pressure ratio of the fan, both of which are the consequences of the increase in bypass ratio. The HBPR engines are typically very large in diameter and can produce over 100,000 pounds of thrust for the largest engines. A third type of engine flying today is the turbo-shaft which is mainly used to power turboprop aircraft and helicopters

  3. Contemporary theories of 1/f noise in motor control.

    Science.gov (United States)

    Diniz, Ana; Wijnants, Maarten L; Torre, Kjerstin; Barreiros, João; Crato, Nuno; Bosman, Anna M T; Hasselman, Fred; Cox, Ralf F A; Van Orden, Guy C; Delignières, Didier

    2011-10-01

    1/f noise has been discovered in a number of time series collected in psychological and behavioral experiments. This ubiquitous phenomenon has been ignored for a long time and classical models were not designed for accounting for these long-range correlations. The aim of this paper is to present and discuss contrasted theoretical perspectives on 1/f noise, in order to provide a comprehensive overview of current debates in this domain. In a first part, we propose a formal definition of the phenomenon of 1/f noise, and we present some commonly used methods for measuring long-range correlations in time series. In a second part, we develop a theoretical position that considers 1/f noise as the hallmark of system complexity. From this point of view, 1/f noise emerges from the coordination of the many elements that compose the system. In a third part, we present a theoretical counterpoint suggesting that 1/f noise could emerge from localized sources within the system. In conclusion, we try to draw some lines of reasoning for going beyond the opposition between these two approaches.

  4. Interior noise control ground test studies for advanced turboprop aircraft applications

    Science.gov (United States)

    Simpson, Myles A.; Cannon, Mark R.; Burge, Paul L.; Boyd, Robert P.

    1989-01-01

    The measurement and analysis procedures are documented, and the results of interior noise control ground tests conducted on a DC-9 aircraft test section are summarized. The objectives of these tests were to study the fuselage response characteristics of treated and untreated aircraft with aft-mount advanced turboprop engines and to analyze the effectiveness of selected noise control treatments in reducing passenger cabin noise on these aircraft. The results of fuselage structural mode surveys, cabin cavity surveys and sound intensity surveys are presented. The performance of various structural and cabin sidewall treatments is assessed, based on measurements of the resulting interior noise levels under simulated advanced turboprop excitation.

  5. Distinct promoter activation mechanisms modulate noise-driven HIV gene expression

    Science.gov (United States)

    Chavali, Arvind K.; Wong, Victor C.; Miller-Jensen, Kathryn

    2015-12-01

    Latent human immunodeficiency virus (HIV) infections occur when the virus occupies a transcriptionally silent but reversible state, presenting a major obstacle to cure. There is experimental evidence that random fluctuations in gene expression, when coupled to the strong positive feedback encoded by the HIV genetic circuit, act as a ‘molecular switch’ controlling cell fate, i.e., viral replication versus latency. Here, we implemented a stochastic computational modeling approach to explore how different promoter activation mechanisms in the presence of positive feedback would affect noise-driven activation from latency. We modeled the HIV promoter as existing in one, two, or three states that are representative of increasingly complex mechanisms of promoter repression underlying latency. We demonstrate that two-state and three-state models are associated with greater variability in noisy activation behaviors, and we find that Fano factor (defined as variance over mean) proves to be a useful noise metric to compare variability across model structures and parameter values. Finally, we show how three-state promoter models can be used to qualitatively describe complex reactivation phenotypes in response to therapeutic perturbations that we observe experimentally. Ultimately, our analysis suggests that multi-state models more accurately reflect observed heterogeneous reactivation and may be better suited to evaluate how noise affects viral clearance.

  6. Cooperating or fighting with control noise in the optimal manipulation of quantum dynamics.

    Science.gov (United States)

    Shuang, Feng; Rabitz, Herschel

    2004-11-15

    This paper investigates the impact of control field noise on the optimal manipulation of quantum dynamics. Simulations are performed on several multilevel quantum systems with the goal of population transfer in the presence of significant control noise. The noise enters as run-to-run variations in the control amplitude and phase with the observation being an ensemble average over many runs as is commonly done in the laboratory. A genetic algorithm with an improved elitism operator is used to find the optimal field that either fights against or cooperates with control field noise. When seeking a high control yield it is possible to find fields that successfully fight with the noise while attaining good quality stable results. When seeking modest control yields, fields can be found which are optimally shaped to cooperate with the noise and thereby drive the dynamics more efficiently. In general, noise reduces the coherence of the dynamics, but the results indicate that population transfer objectives can be met by appropriately either fighting or cooperating with noise, even when it is intense.

  7. Noise control, sound, and the vehicle design process

    Science.gov (United States)

    Donavan, Paul

    2005-09-01

    For many products, noise and sound are viewed as necessary evils that need to be dealt with in order to bring the product successfully to market. They are generally not product ``exciters'' although some vehicle manufacturers do tune and advertise specific sounds to enhance the perception of their products. In this paper, influencing the design process for the ``evils,'' such as wind noise and road noise, are considered in more detail. There are three ingredients to successfully dealing with the evils in the design process. The first of these is knowing how excesses in noise effects the end customer in a tangible manner and how that effects customer satisfaction and ultimately sells. The second is having and delivering the knowledge of what is required of the design to achieve a satisfactory or even better level of noise performance. The third ingredient is having the commitment of the designers to incorporate the knowledge into their part, subsystem or system. In this paper, the elements of each of these ingredients are discussed in some detail and the attributes of a successful design process are enumerated.

  8. Identification procedures for the charge-controlled nonlinear noise model of microwave electron devices

    Science.gov (United States)

    Filicori, Fabio; Traverso, Pier Andrea; Florian, Corrado; Borgarino, Mattia

    2004-05-01

    The basic features of the recently proposed Charge-Controlled Non-linear Noise (CCNN) model for the prediction of low-to-high-frequency noise up-conversion in electron devices under large-signal RF operation are synthetically presented. It is shown that the different noise generation phenomena within the device can be described by four equivalent noise sources, which are connected at the ports of a "noiseless" device model and are non-linearly controlled by the time-varying instantaneous values of the intrinsic device voltages. For the empirical identification of the voltage-controlled equivalent noise sources, different possible characterization procedures, based not only on conventional low-frequency noise data, but also on different types of noise measurements carried out under large-signal RF operating conditions are discussed. As an example of application, the measurement-based identification of the CCNN model for a GaInP heterojunction bipolar microwave transistor is presented. Preliminary validation results show that the proposed model can describe with adequate accuracy not only the low-frequency noise of the HBT, but also its phase-noise performance in a prototype VCO implemented by using the same monolithic GaAs technology.

  9. Advanced Trailing Edge Blowing Concepts for Fan Noise Control

    Directory of Open Access Journals (Sweden)

    Cezar RIZEA

    2012-03-01

    Full Text Available This study documents trailing edge blowing research performed to reduce rotor / stator interaction noise in turbofan engines. The existing technique of filling every velocity deficit requires a large amount of air and is therefore impractical. The purpose of this research is to investigate new blowing configurations in order to achieve noise reduction with lesser amounts of air. Using the new configurations air is not injected into every fan blade, but is instead varied circumferentially. For example, blowing air may be applied to alternating fan blades. This type of blowing configuration both reduces the amount of air used and changes the spectral shape of the tonal interaction noise. The original tones at the blade passing frequency and its harmonics are reduced and new tones are introduced between them. This change in the tonal spectral shape increases the performance of acoustic liners used in conjunction with trailing edge blowing.

  10. On the investigation of voltage controlled oscillator phase noise for IoT applications

    Directory of Open Access Journals (Sweden)

    Haddad F.

    2016-01-01

    Full Text Available Voltage controlled oscillator (VCO is one of the key elements in radio frequency (RF transceivers. A VCO working at 2.4 GHz and designed in CMOS technology is presented. It is suitable for low-cost and low-noise applications using wireless standards such as ZigBee, Bluetooth, Wi-Fi and WPAN (Wireless Personal Area Network. The noise characteristics of this RF VCO are investigated. Noise measurements, especially, phase noise are achieved under different environmental conditions.

  11. Active-passive gradient shielding for MRI acoustic noise reduction.

    Science.gov (United States)

    Edelstein, William A; Kidane, Tesfaye K; Taracila, Victor; Baig, Tanvir N; Eagan, Timothy P; Cheng, Yu-Chung N; Brown, Robert W; Mallick, John A

    2005-05-01

    An important source of MRI acoustic noise-magnet cryostat warm-bore vibrations caused by eddy-current-induced forces-can be mitigated by a passive metal shield mounted on the outside of a vibration-isolated, vacuum-enclosed shielded gradient set. Finite-element (FE) calculations for a z-gradient indicate that a 2-mm-thick Cu layer wrapped on the gradient assembly can decrease mechanical power deposition in the warm bore and reduce warm-bore acoustic noise production by about 25 dB. Eliminating the conducting warm bore and other magnet parts as significant acoustic noise sources could lead to the development of truly quiet, fully functioning MRI systems with noise levels below 70 dB.

  12. Cortical activity predicts which older adults recognize speech in noise and when.

    Science.gov (United States)

    Vaden, Kenneth I; Kuchinsky, Stefanie E; Ahlstrom, Jayne B; Dubno, Judy R; Eckert, Mark A

    2015-03-04

    Speech recognition in noise can be challenging for older adults and elicits elevated activity throughout a cingulo-opercular network that is hypothesized to monitor and modify behaviors to optimize performance. A word recognition in noise experiment was used to test the hypothesis that cingulo-opercular engagement provides performance benefit for older adults. Healthy older adults (N = 31; 50-81 years of age; mean pure tone thresholds recognition in multitalker babble at 2 signal-to-noise ratios (SNR = +3 or +10 dB) during a sparse sampling fMRI experiment. Elevated cingulo-opercular activity was associated with an increased likelihood of correct recognition on the following trial independently of SNR and performance on the preceding trial. The cingulo-opercular effect increased for participants with the best overall performance. These effects were lower for older adults compared with a younger, normal-hearing adult sample (N = 18). Visual cortex activity also predicted trial-level recognition for the older adults, which resulted from discrete decreases in activity before errors and occurred for the oldest adults with the poorest recognition. Participants demonstrating larger visual cortex effects also had reduced fractional anisotropy in an anterior portion of the left inferior frontal-occipital fasciculus, which projects between frontal and occipital regions where activity predicted word recognition. Together, the results indicate that older adults experience performance benefit from elevated cingulo-opercular activity, but not to the same extent as younger adults, and that declines in attentional control can limit word recognition. Copyright © 2015 the authors 0270-6474/15/353929-09$15.00/0.

  13. Noise in brain activity engenders perception and influences discrimination sensitivity.

    Science.gov (United States)

    Bernasconi, Fosco; De Lucia, Marzia; Tzovara, Athina; Manuel, Aurelie L; Murray, Micah M; Spierer, Lucas

    2011-12-07

    Behavioral and brain responses to identical stimuli can vary with experimental and task parameters, including the context of stimulus presentation or attention. More surprisingly, computational models suggest that noise-related random fluctuations in brain responses to stimuli would alone be sufficient to engender perceptual differences between physically identical stimuli. In two experiments combining psychophysics and EEG in healthy humans, we investigated brain mechanisms whereby identical stimuli are (erroneously) perceived as different (higher vs lower in pitch or longer vs shorter in duration) in the absence of any change in the experimental context. Even though, as expected, participants' percepts to identical stimuli varied randomly, a classification algorithm based on a mixture of Gaussians model (GMM) showed that there was sufficient information in single-trial EEG to reliably predict participants' judgments of the stimulus dimension. By contrasting electrical neuroimaging analyses of auditory evoked potentials (AEPs) to the identical stimuli as a function of participants' percepts, we identified the precise timing and neural correlates (strength vs topographic modulations) as well as intracranial sources of these erroneous perceptions. In both experiments, AEP differences first occurred ~100 ms after stimulus onset and were the result of topographic modulations following from changes in the configuration of active brain networks. Source estimations localized the origin of variations in perceived pitch of identical stimuli within right temporal and left frontal areas and of variations in perceived duration within right temporoparietal areas. We discuss our results in terms of providing neurophysiologic evidence for the contribution of random fluctuations in brain activity to conscious perception.

  14. Design, Simulation and Implementation of an Active Sound-Noise Cancellation System for Use in a Cockpit Intercommunication System

    Directory of Open Access Journals (Sweden)

    O. Sharifi-Tehrani

    2012-10-01

    Full Text Available In this paper, an active noise control system for denoising the intercommunication signal of an airplane cockpit isproposed. Noise sources such as engines degrade the quality of the intercommunication signal, especially in the caseof the pilot and copilot headsets. A two-microphone active adaptive noise controller is designed by using an adaptiveFIR filter in an active structure. The designed system is simulated and also implemented in real environment usingreal speech signals, periodic noise and AWGN noise. Also, an FPGA-based hardware implementation utilizing a novelmethod is provided. The whole design is considered an FPGA hardware core with low resource utilizations which issuitable for HW/SW codesign and System-on-Programmable-Chip (SoPC applications. The codes have been writtenby using the VHDL93 hardware description language, the XilKernel embedded operating system and a finite statemachine. The obtained results showed competent functionality and performance of the proposed system. This ICSnoise removal architecture can be used on any cargo, civil or fighter platform (such as C-130, IR-AN 140 and F5-Fand also in radar and electronic warfare (EW systems (for clutter/interference compensation with minimum hardwareor software changes.

  15. Through-wall imaging and characterization of human activity using ultrawideband (UWB) random noise radar

    Science.gov (United States)

    Lai, Chieh-Ping; Narayanan, Ram M.

    2005-05-01

    Recent terrorist activities and law-enforcement situations involving hostage situations underscore the need for effective through-wall imaging. Current building interior imaging systems are based on short-pulse waveforms, which require specially designed antennas to subdue unwanted ringing. In addition, periodically transmitted pulses of energy are easily recognizable by the intelligent adversary who may employ appropriate countermeasures to confound detection. A coherent polarimetric random noise radar architecture is being developed based on UWB technology and software defined radio, which has great promise in its ability to covertly image obscured targets. The main advantages of the random noise radar lie in two aspects: first, random noise waveform has an ideal "thumbtack" ambiguity function, i.e., its down range and cross range resolution can be separately controlled, thus providing unambiguous high resolution imaging at any distance; second, random noise waveform is inherently low probability of intercept (LPI) and low probability of detection (LPD), i.e., it is immune from detection, jamming, and interference. Thus, it is an ideal candidate sensor for covert imaging of obscured regions in hostile environments. The coherency in the system can be exploited to field a fully-polarimetric system that can take advantage of polarization features in target recognition. Moving personnel can also be detected using Doppler processing. Simulation studies are used to analyze backscattered signals from the walls, and humans and other targets behind the walls. Real-time data processing shows human activity behind the wall and human target tracking. The high resolution provides excellent multipath and clutter rejection.

  16. Inexact fuzzy integer chance constraint programming approach for noise control within an urban environment

    Science.gov (United States)

    Huang, Kai; Huang, Gordon; Dai, Liming; Fan, Yurui

    2016-08-01

    This article introduces an inexact fuzzy integer chance constraint programming (IFICCP) approach for identifying noise reduction strategy under uncertainty. The IFICCP method integrates the interval programming and fuzzy chance constraint programming approaches into a framework, which is able to deal with uncertainties expressed as intervals and fuzziness. The proposed IFICCP model can be converted into two deterministic submodels corresponding to the optimistic and pessimistic conditions. The modelling approach is applied to a hypothetical control measure selection problem for noise reduction. Results of the case study indicate that useful solutions for noise control practices can be acquired. Three acceptable noise levels for two communities are considered. For each acceptable noise level, several decision alternatives have been obtained and analysed under different fuzzy confidence levels, which reflect the trade-offs between environmental and economic considerations.

  17. 40 CFR 2.303 - Special rules governing certain information obtained under the Noise Control Act of 1972.

    Science.gov (United States)

    2010-07-01

    ... information obtained under the Noise Control Act of 1972. 2.303 Section 2.303 Protection of Environment... Special rules governing certain information obtained under the Noise Control Act of 1972. (a) Definitions. For the purposes of this section: (1) Act means the Noise Control Act of 1972, 42 U.S.C. 4901 et...

  18. Phase noise analysis of voltage controlled oscillator used in cesium atomic clock

    Science.gov (United States)

    Zhi, Menghui; Tang, Liang; Qiao, Donghai

    2017-03-01

    Coherent population trapping (CPT) cesium frequency standard plays a significant role in precision guidance of missile and global positioning system (GPS). Low noise 4.596 GHz voltage controlled oscillator (VCO) is an indispensable part of microwave signal source in cesium frequency standard. Low-phase noise is also the most important and difficult performance indicator of VCO. Starting from phase noise analysis method proposed by Leeson, the formulas about the relationship between phase noise of output signal of oscillator feedback model and phase fluctuation spectrum of amplifier, phase noise of oscillator are derived in this paper. Finally, the asymptote model of microwave oscillator is proposed based on the formula derivation. The experiment shows that when the reverse bias voltage of variode is 1.8 V, the designed oscillation frequency of VCO is 4.596 GHz, the power is ‑1 dBm and the DC power consumption is 19.6 mW. The tendency of phase noise simulation curve and actual test curve conform to asymptote model. The phase noise in 1 and 10 kHz is, respectively, ‑60.86 and ‑86.58 dBc/Hz. The significance of the paper lies in determining the main factors influencing oscillator phase noise and providing guiding direction for the design of low-phase noise VCO.

  19. Control design for discrete-time state-multiplicative noise stochastic systems

    Science.gov (United States)

    Krokavec, Dušan; Filasová, Anna

    2015-11-01

    Design conditions for existence of the H∞ linear state feedback control for discretetime stochastic systems with state-multiplicative noise and polytopic uncertainties are presented in the paper. Using an enhanced form of the bounded real lemma for discrete-time stochastic systems with state-multiplicative noise, the LMI-based procedure is provided for computation of the gains of linear, as well as nonlinear, state control law. The approach is illustrated on an example demonstrating the validity of the proposed method.

  20. Multichannel control systems for the attenuation of interior road noise in vehicles

    Science.gov (United States)

    Cheer, Jordan; Elliott, Stephen J.

    2015-08-01

    This paper considers the active control of road noise in vehicles, using either multichannel feedback control, with both headrest and floor positioned microphones providing feedback error signals, or multichannel feedforward control, in which reference signals are provided by the microphones on the vehicle floor and error signals are provided by the microphones mounted on the headrests. The formulation of these control problems is shown to be similar if the constraints of robust stability, limited disturbance enhancement and open-loop stability are imposed. A novel formulation is presented for disturbance enhancement in multichannel systems, which limits the maximum enhancement of each individual error signal. The performance of these two systems is predicted using plant responses and disturbance signals measured in a small city car. The reduction in the sum of the squared pressure signals at the four error microphones for both systems is found to be up to 8 dB at low frequencies and 3 dB on average, where the sound level is particularly high from 80 to 180 Hz. The performance of both systems is found to be robust to measured variations in the plant responses. The enhancements in the disturbance at higher frequencies are smaller for the feedback controller than for the feedforward controller, although the performance of the feedback controller is more significantly reduced by the introduction of additional delay in the plant response.

  1. Air Traffic Controllers’ Long-Term Speech-in-Noise Training Effects: A Control Group Study

    Science.gov (United States)

    Zaballos, María T.P.; Plasencia, Daniel P.; González, María L.Z.; de Miguel, Angel R.; Macías, Ángel R.

    2016-01-01

    Introduction: Speech perception in noise relies on the capacity of the auditory system to process complex sounds using sensory and cognitive skills. The possibility that these can be trained during adulthood is of special interest in auditory disorders, where speech in noise perception becomes compromised. Air traffic controllers (ATC) are constantly exposed to radio communication, a situation that seems to produce auditory learning. The objective of this study has been to quantify this effect. Subjects and Methods: 19 ATC and 19 normal hearing individuals underwent a speech in noise test with three signal to noise ratios: 5, 0 and −5 dB. Noise and speech were presented through two different loudspeakers in azimuth position. Speech tokes were presented at 65 dB SPL, while white noise files were at 60, 65 and 70 dB respectively. Results: Air traffic controllers outperform the control group in all conditions [Pcontrol group in all conditions. Thus, this study provides evidence that long-term auditory training is indeed useful in achieving better speech-in-noise understanding even in adverse conditions. PMID:27991470

  2. Reactive control of subsonic axial fan noise in a duct.

    Science.gov (United States)

    Liu, Y; Choy, Y S; Huang, L; Cheng, L

    2014-10-01

    Suppressing the ducted fan noise at low frequencies without varying the flow capacity is still a technical challenge. This study examines a conceived device consisting of two tensioned membranes backed with cavities housing the axial fan for suppression of the sound radiation from the axial fan directly. The noise suppression is achieved by destructive interference between the sound fields from the axial fan of a dipole nature and sound radiation from the membrane via vibroacoustics coupling. A two-dimensional model with the flow effect is presented which allows the performance of the device to be explored analytically. The air flow influences the symmetrical behavior and excites the odd in vacuo mode response of the membrane due to kinematic coupling. Such an asymmetrical effect can be compromised with off-center alignment of the axial fan. Tension plays an important role to sustain the performance to revoke the deformation of the membrane during the axial fan operation. With the design of four appropriately tensioned membranes covered by a cylindrical cavity, the first and second blade passage frequencies of the axial fan can be reduced by at least 20 dB. The satisfactory agreement between experiment and theory demonstrates that its feasibility is practical.

  3. [Actuator placement for active sound and vibration control

    Science.gov (United States)

    1997-01-01

    Two refereed journal publications and ten talks given at conferences, seminars, and colloquia resulted from research supported by NASA. They are itemized in this report. The two publications were entitled "Reactive Tabu and Search Sensor Selection in Active Structural Acoustic Control Problems" and "Quelling Cabin Noise in Turboprop Aircraft via Active Control." The conference presentations covered various aspects of actuator placement, including location problems, for active sound and vibration control of cylinders, of commuter jets, of propeller driven or turboprop aircraft, and for quelling aircraft cabin or interior noise.

  4. Environmental noise levels affect the activity budget of the Florida manatee

    Science.gov (United States)

    Miksis-Olds, Jennifer L.; Donaghay, Percy L.; Miller, James H.; Tyack, Peter L.

    2005-09-01

    Manatees inhabit coastal bays, lagoons, and estuaries because they are dependent on the aquatic vegetation that grows in shallow waters. Food requirements force manatees to occupy the same areas in which human activities are the greatest. Noise produced from human activities has the potential to affect these animals by eliciting responses ranging from mild behavioral changes to extreme aversion. This study quantifies the behavioral responses of manatees to both changing levels of ambient noise and transient noise sources. Results indicate that elevated environmental noise levels do affect the overall activity budget of this species. The proportion of time manatees spend feeding, milling, and traveling in critical habitats changed as a function of noise level. More time was spent in the directed, goal-oriented behaviors of feeding and traveling, while less time was spent milling when noise levels were highest. The animals also responded to the transient noise of approaching vessels with changes in behavioral state and movements out of the geographical area. This suggests that manatees detect and respond to changes in environmental noise levels. Whether these changes legally constitute harassment and produce biologically significant effects need to be addressed with hypothesis-driven experiments and long-term monitoring. [For Animal Bioacoustics Best Student Paper Award.

  5. Modelling of tonal noise control from subsonic axial fans using flow control obstructions

    Science.gov (United States)

    Gérard, Anthony; Berry, Alain; Masson, Patrice; Gervais, Yves

    2009-03-01

    This paper investigates the analytical calculation of blade unsteady lift spectrum when interacting with a neighboring obstruction, designed to control tonal noise. The approach used in this paper is to add a secondary unsteady lift mode, of equal intensity but opposite in phase with the primary unsteady lift mode which radiates most of tonal noise, so that the resultant of both primary and secondary modes is null. To control one unsteady lift mode (consequently an acoustic tone) without affecting the harmonics of the controlled mode (consequently the harmonics of the acoustic tone to be controlled), it is important for the secondary unsteady lift to be harmonically selective. We have therefore evaluated the harmonic content of the blade unsteady lift generated by the proposed control obstructions. To this purpose, an original equation is derived using the infinitesimal radial strips theory coupled with the one-dimensional Sears gust analysis. The spectrum of the blade unsteady lift is then analyzed for three types of obstructions: a series of B-trapezoidal obstructions, a B-periodic sinusoidal obstruction and a series of B-rectangular obstructions (where B is the number of blades). The use of salient obstructions leads to a large unsteady lift harmonic content. An optimized wake width of the trapezoidal obstruction leads to a low harmonic content rate of 5.5%. A Gaussian approximation of the measured inflow velocity profile generated by a sinusoidal obstruction leads to a relatively low harmonic content rate of 18.8%, which indicates that most of the energy is contained in the fundamental mode of the blade unsteady lift. Finally, a rotor/rectangular interaction shows that the use of small-width rectangular obstructions leads to a higher harmonic content rate of 58.6%.

  6. Arbitrary quantum control of qubits in the presence of universal noise

    CSIR Research Space (South Africa)

    Green, TJ

    2013-09-01

    Full Text Available be expressed in terms of experimentally relevant spectral characteristics of the noise and of the control, over all Cartesian directions. We formulate control matrices in the time domain to capture the effects of piecewise-constant control, and convert them...

  7. Entanglement dynamics in the presence of controlled unital noise.

    Science.gov (United States)

    Shaham, A; Halevy, A; Dovrat, L; Megidish, E; Eisenberg, H S

    2015-06-10

    Quantum entanglement is notorious for being a very fragile resource. Significant efforts have been put into the study of entanglement degradation in the presence of a realistic noisy environment. Here, we present a theoretical and an experimental study of the decoherence properties of entangled pairs of qubits. The entanglement dynamics of maximally entangled qubit pairs is shown to be related in a simple way to the noise representation in the Bloch sphere picture. We derive the entanglement level in the case when both qubits of a Bell state are transmitted through any arbitrary unital Pauli channel, and compare it to the case when the channel is applied only to one of the qubits. The dynamics of both cases was verified experimentally using an all-optical setup. We further investigated the evolution of partially entangled initial states. Different dynamics was observed for initial mixed and pure states of the same entanglement level.

  8. Calcium-activated potassium conductance noise in snail neurons.

    Science.gov (United States)

    Westerfield, M; Lux, H D

    1982-11-01

    Current fluctuations were measured in small, 3-6 micrometers-diameter patches of soma membrane in bursting neurons of the snail, Helix pomatia. The fluctuations dramatically increased in magnitude with depolarization of the membrane potential under voltage clamp conditions. Two components of conductance noise were identified in the power spectra calculated from the membrane currents. One component had a corner frequency which increased with depolarization. This component was blocked by intracellular injection of TEA and was relatively insensitive to extracellular calcium levels (as long as the total number of effective divalent cations remained constant). It was identified as fluctuations of the voltage-dependent component of delayed outward current. The second component of conductance noise had a corner frequency which decreased with depolarization. It was relatively unaffected by TEA injection and was reversibly blocked by substitution of extracellular calcium with magnesium, cobalt, or nickel. This second component of noise was identified as fluctuations of the calcium-dependent potassium current. The results suggest that the two components of delayed outward current are conducted through physically distinct channels.

  9. Noise power associated with decreased task-induced variability of brain electrical activity in schizophrenia.

    Science.gov (United States)

    Molina, Vicente; Bachiller, Alejandro; Suazo, Vanessa; Lubeiro, Alba; Poza, Jesús; Hornero, Roberto

    2016-02-01

    In schizophrenia, both increased baseline metabolic and electroencephalographic (EEG) activities as well as decreased task-related modulation of neural dynamics have been reported. Noise power (NP) can measure the background EEG activity during task performance, and Shannon entropy (SE) is useful for quantifying the global modulation of EEG activity with a high temporal resolution. In this study, we have assessed the possible relationship between increased NP in theta and gamma bands and decreased SE modulation in 24 patients with schizophrenia and 26 controls over the parietal and central regions during a P300 task. SE modulation was calculated as the change from baseline to the active epoch (i.e., 150-550 ms following the target stimulus onset). Patients with schizophrenia displayed statistically significant higher NP values and lower SE modulation than healthy controls. We found a significant association between gamma NP and SE in all of the participants. Specifically, a NP increase in the gamma band was followed by a decrease in SE change. These results support the notion that an excess of gamma activity, unlocked to the task being performed, is accompanied by a decreased modulation of EEG activity in schizophrenia.

  10. Design of multi-modal obstruction to control tonal fan noise using modulation principles

    Science.gov (United States)

    Gérard, Anthony; Moreau, Stéphane; Berry, Alain; Masson, Patrice

    2015-11-01

    The approach presented in this paper uses a combination of obstructions in the upstream flow of subsonic axial fans with B blades to destructively interfere with the primary tonal noise at the blade passage frequency. The first step of the proposed experimental method consists in identifying the independent radiation of B - 1 and B lobed obstructions at the control microphones. During this identification step, rotating obstructions allow for the frequencies of primary and secondary tonal noise to be slightly shifted in the spectrum due to modulation principles. The magnitude of the secondary tonal noise generated by each obstruction can be adjusted by varying the size of the lobes of the obstruction, and the phase of the secondary tonal noise is related to the angular position of the obstruction. The control obstructions are then optimized by combining the B - 1 and B lobed obstructions to significantly reduce the acoustic power at blade passage frequency.

  11. Speech Waveform Compression Using Robust Adaptive Voice Activity Detection for Nonstationary Noise

    Directory of Open Access Journals (Sweden)

    Hsiao-Chun Wu

    2008-03-01

    Full Text Available The voice activity detection (VAD is crucial in all kinds of speech applications. However, almost all existing VAD algorithms suffer from the nonstationarity of both speech and noise. To combat this difficulty, we propose a new voice activity detector, which is based on the Mel-energy features and an adaptive threshold related to the signal-to-noise ratio (SNR estimates. In this paper, we first justify the robustness of the Bayes classifier using the Mel-energy features over that using the Fourier spectral features in various noise environments. Then, we design an algorithm using the dynamic Mel-energy estimator and the adaptive threshold, which depends on the SNR estimates. In addition, a realignment scheme is incorporated to correct the sparse-and-spurious noise estimates. Numerous simulations are carried out to evaluate the performance of our proposed VAD method and the comparisons are made with a couple of existing representative schemes, namely, the VAD using the likelihood ratio test with Fourier spectral energy features and that based on the enhanced time-frequency parameters. Three types of noises, namely, white noise (stationary, babble noise (nonstationary, and vehicular noise (nonstationary were artificially added by the computer for our experiments. As a result, our proposed VAD algorithm significantly outperforms other existing methods as illustrated by the corresponding receiver operating characteristics (ROC curves. Finally, we demonstrate one of the major applications, namely, speech waveform compression associated with our new robust VAD scheme and quantify the effectiveness in terms of compression efficiency.

  12. Temporal pattern of acoustic imaging noise asymmetrically modulates activation in the auditory cortex.

    Science.gov (United States)

    Ranaweera, Ruwan D; Kwon, Minseok; Hu, Shuowen; Tamer, Gregory G; Luh, Wen-Ming; Talavage, Thomas M

    2016-01-01

    This study investigated the hemisphere-specific effects of the temporal pattern of imaging related acoustic noise on auditory cortex activation. Hemodynamic responses (HDRs) to five temporal patterns of imaging noise corresponding to noise generated by unique combinations of imaging volume and effective repetition time (TR), were obtained using a stroboscopic event-related paradigm with extra-long (≥27.5 s) TR to minimize inter-acquisition effects. In addition to confirmation that fMRI responses in auditory cortex do not behave in a linear manner, temporal patterns of imaging noise were found to modulate both the shape and spatial extent of hemodynamic responses, with classically non-auditory areas exhibiting responses to longer duration noise conditions. Hemispheric analysis revealed the right primary auditory cortex to be more sensitive than the left to the presence of imaging related acoustic noise. Right primary auditory cortex responses were significantly larger during all the conditions. This asymmetry of response to imaging related acoustic noise could lead to different baseline activation levels during acquisition schemes using short TR, inducing an observed asymmetry in the responses to an intended acoustic stimulus through limitations of dynamic range, rather than due to differences in neuronal processing of the stimulus. These results emphasize the importance of accounting for the temporal pattern of the acoustic noise when comparing findings across different fMRI studies, especially those involving acoustic stimulation.

  13. Guaranteed control performance robust LQG regulator for discrete-time Markovian jump systems with uncertain noise

    Institute of Scientific and Technical Information of China (English)

    Zhu Jin; Xi Hongsheng; Xiao Xiaobo; Ji Haibo

    2007-01-01

    Robust LQG problems of discrete-time Markovian jump systems with uncertain noises are investigated.The problem addressed is the construction of perturbation upper bounds on the uncertain noise covariances so as to guarantee that the deviation of the control performance remains within the precision prescribed in actual problems.Furthermore, this regulator is capable of minimizing the worst performance in an uncertain case. A numerical example is exploited to show the validity of the method.

  14. Signal-Noise Ratio Control Subsystem of Digital Equipment for Transmission of "Strela" Relay Protection Commands

    Directory of Open Access Journals (Sweden)

    I. Zabenkov

    2012-01-01

    Full Text Available Continuous measurement function of relative noise and interference level in the information transmission channel is considered as an important one for controlling parameters of high-frequency signal. The present paper simulates an algorithm for measuring signal-noise ratio in the transmission channel of high-voltage lines which is used in the digital equipment for transmission of relay protection and emergency automation commands of "Strela" complex.

  15. Suppression of charge noise using barrier control of a singlet-triplet qubit

    Science.gov (United States)

    Yang, Xu-Chen; Wang, Xin

    2017-07-01

    It has been recently demonstrated that a singlet-triplet spin qubit in semiconductor double quantum dots can be controlled by changing the height of the potential barrier between the two dots ("barrier control"), which has led to a considerable reduction of charge noises as compared with the traditional tilt control method. In this paper we show, through a molecular-orbital-theoretic calculation of double quantum dots influenced by a charged impurity, that the relative charge noise for a system under the barrier control not only is smaller than that for the tilt control but actually decreases as a function of an increasing exchange interaction. This is understood as a combined consequence of the greatly suppressed detuning noise when the two dots are symmetrically operated, as well as an enhancement of the interdot hopping energy of an electron when the barrier is lowered which in turn reduces the relative charge noise at large exchange interaction values. We have also studied the response of the qubit to charged impurities at different locations and found that the improvement of barrier control is least for impurities equidistant from the two dots due to the small detuning noise they cause but is otherwise significant along other directions.

  16. Lead-Lag Control for Helicopter Vibration and Noise Reduction

    Science.gov (United States)

    Gandhi, Farhan

    1995-01-01

    As a helicopter transitions from hover to forward flight, the main rotor blades experience an asymmetry in flow field around the azimuth, with the blade section tangential velocities increasing on the advancing side and decreasing on the retreating side. To compensate for the reduced dynamic pressure on the retreating side, the blade pitch angles over this part of the rotor disk are increased. Eventually, a high enough forward speed is attained to produce compressibility effects on the advancing side of the rotor disk and stall on the retreating side. The onset of these two phenomena drastically increases the rotor vibratory loads and power requirements, thereby effectively establishing a limit on the maximum achievable forward speed. The alleviation of compressibility and stall (and the associated decrease in vibratory loads and power) would potentially result in an increased maximum forward speed. In the past, several methods have been examined and implemented to reduce the vibratory hub loads. Some of these methods are aimed specifically at alleviating vibration at very high flight speeds and increasing the maximum flight speed, while others focus on vibration reduction within the conventional flight envelope. Among the later are several types passive as well as active schemes. Passive schemes include a variety of vibration absorbers such as mechanical springs, pendulums, and bifilar absorbers. These mechanism are easy to design and maintain, but incur significant weight and drag penalties. Among the popular active control schemes in consideration are Higher Harmonic Control (HHC) and Individual Blade Control (IBC). HHC uses a conventional swash plate to generate a multi-cyclic pitch input to the blade. This requires actuators capable of sufficiently high power and bandwidth, increasing the cost and weight of the aircraft. IBC places actuators in the rotating reference frame, requiring the use of slip rings capable of transferring enough power to the actuators

  17. Lévy noise improves the electrical activity in a neuron under electromagnetic radiation.

    Science.gov (United States)

    Wu, Juan; Xu, Yong; Ma, Jun

    2017-01-01

    As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

  18. PDE-based random-valued impulse noise removal based on new class of controlling functions.

    Science.gov (United States)

    Wu, Jian; Tang, Chen

    2011-09-01

    This paper is concerned with partial differential equation (PDE)-based image denoising for random-valued impulse noise. We introduce the notion of ENI (the abbreviation for "edge pixels, noisy pixels, and interior pixels") that denotes the number of homogeneous pixels in a local neighborhood and is significantly different for edge pixels, noisy pixels, and interior pixels. We redefine the controlling speed function and the controlling fidelity function to depend on ENI. According to our two controlling functions, the diffusion and fidelity process at edge pixels, noisy pixels, and interior pixels can be selectively carried out. Furthermore, a class of second-order improved and edge-preserving PDE denoising models is proposed based on the two new controlling functions in order to deal with random-valued impulse noise reliably. We demonstrate the performance of the proposed PDEs via application to five standard test images, corrupted by random-valued impulse noise with various noise levels and comparison with the related second-order PDE models and the other special filtering methods for random-valued impulse noise. Our two controlling functions are extended to automatically other PDE models.

  19. Diffusion of active particles with stochastic torques modeled as α-stable noise

    Science.gov (United States)

    Nötel, Jörg; Sokolov, Igor M.; Schimansky-Geier, Lutz

    2017-01-01

    We investigate the stochastic dynamics of an active particle moving at a constant speed under the influence of a fluctuating torque. In our model the angular velocity is generated by a constant torque and random fluctuations described as a Lévy-stable noise. Two situations are investigated. First, we study white Lévy noise where the constant speed and the angular noise generate a persistent motion characterized by the persistence time {τ }D. At this time scale the crossover from ballistic to normal diffusive behavior is observed. The corresponding diffusion coefficient can be obtained analytically for the whole class of symmetric α-stable noises. As typical for models with noise-driven angular dynamics, the diffusion coefficient depends non-monotonously on the angular noise intensity. As second example, we study angular noise as described by an Ornstein–Uhlenbeck process with correlation time {τ }c driven by the Cauchy white noise. We discuss the asymptotic diffusive properties of this model and obtain the same analytical expression for the diffusion coefficient as in the first case which is thus independent on {τ }c. Remarkably, for {τ }c\\gt {τ }D the crossover from a non-Gaussian to a Gaussian distribution of displacements takes place at a time {τ }G which can be considerably larger than the persistence time {τ }D.

  20. Diffusion of Active Particles With Stochastic Torques Modeled as $\\alpha$-Stable Noise

    CERN Document Server

    Noetel, Joerg; Schimansky-Geier, Lutz

    2016-01-01

    We investigate the stochastic dynamics of an active particle moving at a constant speed under the influence of a fluctuating torque. In our model the angular velocity is generated by a constant torque and random fluctuations described as a L\\'evy-stable noise. Two situations are investigated. First, we study white L\\'evy noise where the constant speed and the angular noise generate a persistent motion characterized by the persistence time $\\tau_D$. At this time scale the crossover from ballistic to normal diffusive behavior is observed. The corresponding diffusion coefficient can be obtained analytically for the whole class of symmetric $\\alpha$-stable noises. As typical for models with noise-driven angular dynamics, the diffusion coefficient depends non-monotonously on the angular noise intensity. As second example, we study angular noise as described by an Ornstein-Uhlenbeck process with correlation time $\\tau_c$ driven by the Cauchy white noise. We discuss the asymptotic diffusive properties of this model ...

  1. A bulk-controlled ring-VCO with 1/f-noise reduction for frequency ΔΣ modulator

    DEFF Research Database (Denmark)

    Tuan Vu, CAO; Wisland, Dag T.; Lande, Tor Sverre

    The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub......-threshold to saturation. By using the 1/f-noise reduction circuit which is based on the switched bias technique, the simulations indicate that less noise is transferred to the output when the 1/f-noise reduction circuit is used. The phase noise of the proposed VCO is improved by 7.6% while maintaining tuning...

  2. Innovative Control of Noise and Vibration of Industrial Equipments and Machines

    Directory of Open Access Journals (Sweden)

    Owhor, Sampson Chisa,

    2015-05-01

    Full Text Available Noise and Vibration of industrial equipment is the grave factor influencing its production state, working conditions of staff and job safety. In course of technology development the more potent machines are used, it is quite often accompanied by an increase of vibration and noise level. This is experienced by equipment as it is transmitted to building structures, environment and through staffs. The system of equation advocated in this research work has been permitted to evaluate reduction of machine vibrations caused by unbalance movement of its members, thereby transmitting it onto the floor and the environment. A noise problem generally consists of three inter-related elements- the source, the receiver and the transmission path. This transmission path is usually the atmosphere through which the sound is propagated, but can include structural materials of any building containing the receiver. The development of innovative noise control treatments provides opportunities for applying basic physics and engineering procedures.

  3. H∞ Control for Nonlinear Stochastic Systems with Time-Delay and Multiplicative Noise

    Directory of Open Access Journals (Sweden)

    Ming Gao

    2015-01-01

    Full Text Available This paper studies the infinite horizon H∞ control problem for a general class of nonlinear stochastic systems with time-delay and multiplicative noise. The exponential/asymptotic mean square H∞ control design of delayed nonlinear stochastic systems is presented by solving Hamilton-Jacobi inequalities. Two numerical examples are provided to show the effectiveness of the proposed design method.

  4. From bounded-noise data to robust PI-controller design

    NARCIS (Netherlands)

    Steinbuch, Luc; Keesman, K.J.

    2015-01-01

    An approach is presented to design a robust PI-controller from bounded noise measurement data of a first order process with and without time delay. This controller guarantees a known robust performance. It is shown that in the case without time delay, the conservatism of the robust approach can b

  5. Assessing Measurement Noise Effect in Run-to-Run Process Control: Extends EWMA Controller by Kalman Filter

    Directory of Open Access Journals (Sweden)

    Tzu-Wei Kuo

    2011-09-01

    Full Text Available Recently, the Exponentially Weighted Moving Average (EWMA controller has become a popular control method in Run-to-Run (RtR process control, but the issue of measurement noise from metrology tools has not been addressed in RtR EWMA controllers yet. This paper utilizes a Kalman Filter (KF controller to deal with measurement noise in RtR process control and investigates the output properties for steady-state mean and variance, and for closed-loop stability. Five disturbance models modeling semiconductor process disturbances are investigated. These disturbance models consist of Deterministic Trend (DT, Random Walk with Drift (RWD, Integrated Moving Average process (IMA(1,1, AutoRegressive Moving Average (ARMA(1,1, and Autoregressive Integrated Moving Average (ARIMA(1,1,1.  Analytical results show that a KF controller can be considered as an extended version of a RtR EWMA controller. In particular, the EWMA controller is a special case of KF in a filtering form without the capability of measuring noise. Simulation results also show that the KF has a better ability to deal with measurement noise than the EWMA controller.

  6. ON THE APPLICATION OF PARTIAL BARRIERS FOR SPINNING MACHINE NOISE CONTROL: A THEORETICAL AND EXPERIMENTAL APPROACH

    Directory of Open Access Journals (Sweden)

    M. R. Monazzam, A. Nezafat

    2007-04-01

    Full Text Available Noise is one of the most serious challenges in modern community. In some specific industries, according to the nature of process, this challenge is more threatening. This paper describes a means of noise control for spinning machine based on experimental measurements. Also advantages and disadvantages of the control procedure are added. Different factors which may affect the performance of the barrier in this situation are also mentioned. To provide a good estimation of the control measure, a theoretical formula is also described and it is compared with the field data. Good agreement between the results of filed measurements and theoretical presented model was achieved. No obvious noise reduction was seen by partial indoor barriers in low absorbent enclosed spaces, since the reflection from multiple hard surfaces is the main dominated factor in the tested environment. At the end, the situation of the environment and standards, which are necessary in attaining the ideal results, are explained.

  7. Cross-Cutting Activities 2016 on Wind Turbine Noise, Summary Report

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Aagaard Madsen, Helge; Fischer, Andreas

    2017-01-01

    The goal of this report is to summarize activities that took place in year 2016 as part of the Cross-Cutting Activity on Wind Turbine Noise, self-financed by DTU Wind Energy. A short description of the background behind this project (in particular Cross-Cutting Activities conducted in year 2015...

  8. Entropy as a measure of the noise extent in a two-level quantum feedback controlled system

    Institute of Scientific and Technical Information of China (English)

    Wang Tao-Bo; Fang Mao-Fa; Hu Yao-Hua

    2007-01-01

    By introducing the von Neumann entropy as a measure of the extent of noise, this paper discusses the entropy evolution in a two-level quantum feedback controlled system. The results show that the feedback control can induce the reduction of the degree of noise, and different control schemes exhibit different noise controlling ability, the extent of the reduction also related with the position of the target state on the Bloch sphere. It is shown that the evolution of entropy can provide a real time noise observation and a systematic guideline to make reasonable choice of control strategy.

  9. Noise control of counterflow cooling towers%逆流式冷却塔的噪声治理

    Institute of Scientific and Technical Information of China (English)

    费朝阳; 陈长征; 周勃

    2011-01-01

    根据逆流式冷却塔辐射噪声的实测频谱图,分析了冷却塔的主要噪声来源和频谱特征.分别从吸声、消声和隔声等方面制定了降噪方案,取得了良好的降噪效果.%Based on the measured radiation noise frequency spectrogram, analyses the main noise source and noise spectrum characteristics of cooling tower.Makes a noise control scheme from the aspects of sound absorption, attenuation and insulation.The effect of the noise control is satisfactory.

  10. Output feedback control for a class of nonlinear systems with actuator degradation and sensor noise.

    Science.gov (United States)

    Ai, Weiqing; Lu, Zhenli; Li, Bin; Fei, Shumin

    2016-11-01

    This paper investigates the output feedback control problem of a class of nonlinear systems with sensor noise and actuator degradation. Firstly, by using the descriptor observer approach, the origin system is transformed into a descriptor system. On the basis of the descriptor system, a novel Proportional Derivative (PD) observer is developed to asymptotically estimate sensor noise and system state simultaneously. Then, by designing an adaptive law to estimate the effectiveness of actuator, an adaptive observer-based controller is constructed to ensure that system state can be regulated to the origin asymptotically. Finally, the design scheme is applied to address a flexible joint robot link problem.

  11. Optimal control of light propagation through multiple-scattering media in the presence of noise

    CERN Document Server

    Yilmaz, Hasan; Mosk, Allard P

    2013-01-01

    We study the control of coherent light propagation through multiple-scattering media in the presence of measurement noise. In our experiments, we use a two-step optimization procedure to find the optimal incident wavefront. We conclude that the degree of optimal control of coherent light propagation through a multiple-scattering medium is only determined by the number of photoelectrons detected per single speckle spot. The prediction of our model agrees well with the experimental results. Our results offer opportunities for imaging applications through scattering media such as biological tissue in the shot noise limit.

  12. A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yong, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn; Tao, Gang, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn [School of Energy and Power Engineering, Nanjing University of Science and Technology, 200 XiaoLingwei Street, Nanjing 210094 (China)

    2014-09-01

    The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.

  13. Active Flow Control

    Science.gov (United States)

    FFOWCS WILLIAMS, J. E.

    2001-01-01

    This paper considers the two-dimensional problem of a plane vortex sheet disturbed by an impulsive line source. A previous incorrect treatment of this problem is examined in detail. Instabilities of the vortex sheet are triggered by the source and grow exponentially in space and time. The Green function is constructed for the problem and it is shown that a point source properly positioned and delayed will induce a field that cancels the unstable growing modes. The resulting displacement of the vortex sheet is expressed in simple terms. The instabilities are checked by the anti-source which combines with the field of the primary source into a vortex sheet response which decays with time at large time. This paper is a contribution to the study of active control of shear layer instabilities, the main contribution being to clear up a previous paper with peculiar results that are, in fact, wrong.

  14. Algorithms to Solve Stochastic H2/H∞ Control with State-Dependent Noise

    Directory of Open Access Journals (Sweden)

    Ming Gao

    2014-01-01

    Full Text Available This paper is concerned with the algorithms which solve H2/H∞ control problems of stochastic systems with state-dependent noise. Firstly, the algorithms for the finite and infinite horizon H2/H∞ control of discrete-time stochastic systems are reviewed and studied. Secondly, two algorithms are proposed for the finite and infinite horizon H2/H∞ control of continuous-time stochastic systems, respectively. Finally, several numerical examples are presented to show the effectiveness of the algorithms.

  15. Room acoustic analysis of blower unit and noise control plan in the typical steel industry

    Directory of Open Access Journals (Sweden)

    2013-02-01

    Full Text Available Introduction: In the steel industry,air blowers used to supply compressed air are considered as sources of annoying noise. This study aims to acoustics analysis of theairblower workroomand sound source characteristics in order to present noise controlmeasuresinthe steel industry. .Material and Method: Measurement of noiselevel and its frequency analysis was performed usingsound levelmetermodelof CASELLA-Cell.450. Distribution of noise level in the investigated workroom in form of noise map was provided using Surfer software. In addition, acoustic analysis of workroom and control room was performed in view point of soundabsorption andinsulation. Redesignofdoor and window of controlroom and installation of soundabsorbing materialson theceiling of the workroom were proposed and the efficiency of these interventionswasestimated. .Result: The totalsound pressurelevelin the blower workroom was 95.4 dB(L and the dominant frequency was 2000Hz. Sound pressure level inside the room control was 80.1dB(A. The average absorption coefficient and reverberation time in the blower workroom was estimated equal to 0.082 Sab.m2 and 3.9 seconds respectively. These value in control room was 0.04 Sab.m2 and 3/4 seconds respectively. In control room, sound transmission loss between the two parts of the wall dividing was 13.7 dB(A. The average of noise dose in blower operators was 230%. With the installation of sound absorber on ceiling of workroom, average of absorption coefficient can increase to 0.33 Sab.m2 and sound transmission loss of the new designed door and window was estimated equal to 20dB. . Conclusion: The main cause of noise leakage in the control room was insufficient insulation properties of door and windows. By replacing the door and window and installation of sound absorbing on ceiling of workroom, the noise dose can reduce to 49.6%. New Improved door and window of control room can reduce noise dose to 69.65% solely.

  16. Reward Pays the Cost of Noise Reduction in Motor and Cognitive Control

    Science.gov (United States)

    Manohar, Sanjay G.; Chong, Trevor T.-J.; Apps, Matthew A.J.; Batla, Amit; Stamelou, Maria; Jarman, Paul R.; Bhatia, Kailash P.; Husain, Masud

    2015-01-01

    Summary Speed-accuracy trade-off is an intensively studied law governing almost all behavioral tasks across species. Here we show that motivation by reward breaks this law, by simultaneously invigorating movement and improving response precision. We devised a model to explain this paradoxical effect of reward by considering a new factor: the cost of control. Exerting control to improve response precision might itself come at a cost—a cost to attenuate a proportion of intrinsic neural noise. Applying a noise-reduction cost to optimal motor control predicted that reward can increase both velocity and accuracy. Similarly, application to decision-making predicted that reward reduces reaction times and errors in cognitive control. We used a novel saccadic distraction task to quantify the speed and accuracy of both movements and decisions under varying reward. Both faster speeds and smaller errors were observed with higher incentives, with the results best fitted by a model including a precision cost. Recent theories consider dopamine to be a key neuromodulator in mediating motivational effects of reward. We therefore examined how Parkinson’s disease (PD), a condition associated with dopamine depletion, alters the effects of reward. Individuals with PD showed reduced reward sensitivity in their speed and accuracy, consistent in our model with higher noise-control costs. Including a cost of control over noise explains how reward may allow apparent performance limits to be surpassed. On this view, the pattern of reduced reward sensitivity in PD patients can specifically be accounted for by a higher cost for controlling noise. PMID:26096975

  17. Association between aircraft, road and railway traffic noise and depression in a large case-control study based on secondary data.

    Science.gov (United States)

    Seidler, Andreas; Hegewald, Janice; Seidler, Anna Lene; Schubert, Melanie; Wagner, Mandy; Dröge, Patrik; Haufe, Eva; Schmitt, Jochen; Swart, Enno; Zeeb, Hajo

    2017-01-01

    Few studies have examined the relationship between traffic noise and depression providing inconclusive results. This large case-control study is the first to assess and directly compare depression risks by aircraft, road traffic and railway noise. The study population included individuals aged ≥40 years that were insured by three large statutory health insurance funds and were living in the region of Frankfurt international airport. Address-specific exposure to aircraft, road and railway traffic noise in 2005 was estimated. Based on insurance claims and prescription data, 77,295 cases with a new clinical depression diagnosis between 2006 and 2010 were compared with 578,246 control subjects. For road traffic noise, a linear exposure-risk relationship was found with an odds ratio (OR) of 1.17 (95% CI=1.10-1.25) for 24-h continuous sound levels ≥70dB. For aircraft noise, the risk estimates reached a maximum OR of 1.23 (95% CI=1.19-1.28) at 50-55dB and decreased at higher exposure categories. For railway noise, risk estimates peaked at 60-65dB (OR=1.15, 95% CI=1.08-1.22). The highest OR of 1.42 (95% CI=1.33-1.52) was found for a combined exposure to noise above 50dB from all three sources. This study indicates that traffic noise exposure might lead to depression. As a potential explanation for the decreasing risks at high traffic noise levels, vulnerable people might actively cope with noise (e.g. insulate or move away). Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Cortisol level decreases natural killer cell activity among women with aircraft noise

    Directory of Open Access Journals (Sweden)

    Hartono Hartono

    2016-02-01

    Full Text Available One of the impacts of exposure to noise is stress. Natural killer (NK cells are one of the leukocyte subsets that are responsive to physiological and psychological stress. The objective of the present research was to determine the relationship between cortisol levels and NK cell activity among women with aircraft noise stress in the area of Adi Sumarmo Airport, Solo. This study was an analytical survey with a cross sectional design. The number of subjects was 39, who were divided into 3 groups of 13 subjects each. Groups 1 to 3 were exposed to noise levels of 92.29 dB, 71.79 dB and 52.17 dB, respectively. The sample was taken using simple random sampling. The data were analyzed by Pearson correlation test and Anova followed by post hoc test using LSD test. The Anova test showed that there were significant differences in circulating cortisol levels among all groups (p = 0.018. The Pearson correlation test showed that there was a positive association between circulating cortisol levels and the number of NK cells (r = 0.547; p< 0.05 and a negative association between circulating cortisol levels and NK cell activity (r = - 0.578; p < 0.05. This study indicated that cortisol levels decreased NK cell activity among women with exposure to aircraft noise. Women who experienced aircraft noise stress showed increased cortisol levels and decreased NK cells activity.

  19. Active control of transmission loss with smart foams.

    Science.gov (United States)

    Kundu, Abhishek; Berry, Alain

    2011-02-01

    Smart foams combine the complimentary advantages of passive foam material and spatially distributed piezoelectric actuator embedded in it for active noise control applications. In this paper, the problem of improving the transmission loss of smart foams using active control strategies has been investigated both numerically and experimentally inside a waveguide under the condition of plane wave propagation. The finite element simulation of a coupled noise control system has been undertaken with three different smart foam designs and their effectiveness in cancelling the transmitted wave downstream of the smart foam have been studied. The simulation results provide insight into the physical phenomenon of active noise cancellation and explain the impact of the smart foam designs on the optimal active control results. Experimental studies aimed at implementing the real-time control for transmission loss optimization have been performed using the classical single input/single output filtered-reference least mean squares algorithm. The active control results with broadband and single frequency primary source inputs demonstrate a good improvement in the transmission loss of the smart foams. The study gives a comparative description of the transmission and absorption control problems in light of the modification of the vibration response of the piezoelectric actuator under active control.

  20. Noise-induced ectopic activity in a simple cardiac cell model

    Science.gov (United States)

    Hastings, Harold

    2005-03-01

    Ectopic activity in the form of premature ventricular contractions (PVCs) is relatively common in the normal heart. Although PVCs are normally harmless, sometimes but rarely PVCs can generate spiral waves of activation through interaction with other waves of activation, potentially progressing to ventricular tachycardia, followed by ventricular fibrillation and sudden cardiac death. Clusters of PVCs have been found to be significantly more dangerous than isolated PVCs. We model PVC generation by applying triggers (noise) to the generic FitzHugh-Nagumo model as substrate, and study the effects the noise level and excitability. We find: exponential waiting time behavior at fixed parameter levels; no evidence of clustering at fixed parameter levels; and a sharp increase in PVCs as excitability approaches the auto-oscillatory threshold or noise increases beyond a similar threshold. This produces sharp increases in theoretical rates of PVC-induced fibrillation, consistent with results of A Gelzer et al. in animal models. Partially supported by the NSF and NIH.

  1. Simulation studies for multichannel active vibration control

    Science.gov (United States)

    Prakash, Shashikala; Balasubramaniam, R.; Praseetha, K. K.

    2003-10-01

    Traditional approach to vibration control uses passive techniques, which are relatively large, costly and ineffective at low frequencies. Active Vibration Control (AVC) is used to overcome these problems & in AVC additional sources (secondary) are used to cancel vibration from primary source based on the principle of superposition theorem Since the characteristics of the vibration source and environment are time varying, the AVC system must be adaptive. Adaptive systems have the ability to track time varying disturbances and provide optimal control over a much broader range of conditions than conventional fixed control systems. In multi channel AVC vibration fields in large dimensions are controlled & is more complicated. Therefore to actively control low frequency vibrations on large structures, multi channel AVC requires a control system that uses multiple secondary sources to control the vibration field simultaneously at multiple error sensor locations. The error criterion that can be directly measured is the sum of squares of outputs of number of sensors. The adaptive algorithm is designed to minimize this & the algorithm implemented is the "Multiple error LMS algorithm." The best known applications of multiple channel FXLMS algorithm is in real time AVC and system identification. More wider applications are in the control of propeller induced noise in flight cabin interiors. In the present paper the results of simulation studies carried out in MATLAB as well as on TMS320C32 DSP processor will be brought out for a two-channel case.

  2. Assessment of the need for noise control research on electric power transformers and reactors. Report No. 4289

    Energy Technology Data Exchange (ETDEWEB)

    Keast, D. N.; Gordon, C. G.

    1980-08-01

    This study was conducted to identify and quantify the needs (if any) for noise control research applicable to electric utility transformers and reactors to comply with quantitative state noise regulations. The study was accomplished by analyzing available published data, by studying a sample of utility substation drawings, and by assessing various noise-control design approaches. No experimental work was done. The study was restricted to outdoor substations. A model was prepared to predict noise from existing US substations. A sample of 658 substation designs from five utilities was analyzed to refine the above model and to provide a detailed analysis of the configurations, capacities, and noise-control features of present US substations. A typical substation was defined. Advanced transformer designs (low-loss core, amorphous core, SF/sub 6/-cooled, vapor-cooled, superconducting) for future substations were reviewed to estimate their noise impacts. Noise abatement options were assessed to define where future noise-control research would be appropriate. It was concluded that: at present, about 5% of the electric utility substations in the US, require an average of 14 dBA of noise reduction to comply with existing noise regulations; estimated cost of compliance is about $200 million; and transformer noise is the dominant problem; current technology can provide the necessary noise control, but it is very costly. Additional research and demonstration programs are recommended to reduce the cost of retrofit noise control treatments for existing substations. It is essential that the electric utility industry be involved in guiding this research.

  3. Noise tolerant selection by gaze-controlled pan and zoom in 3D

    DEFF Research Database (Denmark)

    Hansen, Dan Witzner; Jensen, Henrik Skovsgaard; Hansen, John Paulin;

    2008-01-01

    ) the subjects were able to type at acceptable rates. In a second test, seven subjects were allowed to adjust the zooming speed themselves. They achieved typing rates of more than eight words per minute without using language modeling. We conclude that the StarGazer application is an intuitive 3D interface...... tested three different display sizes (down to PDA-sized displays) and found that large screens are faster to navigate than small displays and that the error rate is higher for the smallest display. Half of the subjects were exposed to severe noise deliberately added on the cursor positions. We found...... that this had a negative impact on efficiency. However, the user remained in control and the noise did not seem to effect the error rate. Additionally, three subjects tested the effects of temporally adding noise to simulate latency in the gaze tracker. Even with a significant latency (about 200 ms...

  4. A Low Phase Noise CMOS Quadrature Voltage Control Oscillator Using Clock Gated Technique

    Directory of Open Access Journals (Sweden)

    Jothi Baskar A

    2015-06-01

    Full Text Available This project presents the low phase noise cmos quadrature voltage control oscillator using clock gating technique. Here the colpitts vco is used to split the capacitance in the Qvco circuit producing quadrature output. The startup condition in the oscillator is improved by using enhancement [12].This QVCO performs the operation anti phase injection locking fordevice reuse [8]. The new clock gating technique is used to reduce the power with thepower supply 1.5v. The QVCO uses a 0.5mwith phase error of 0.4 and exhibits a phase noise of -118dBc/HZ at 1MHZ offset at the centre frequency of 500MHZ. Index terms: current switching, clock gating, phase noise, Qvco

  5. Thin broadband noise absorption through acoustic reactance control by electro-mechanical coupling without sensor.

    Science.gov (United States)

    Zhang, Yumin; Chan, Yum-Ji; Huang, Lixi

    2014-05-01

    Broadband noise with profound low-frequency profile is prevalent and difficult to be controlled mechanically. This study demonstrates effective broadband sound absorption by reducing the mechanical reactance of a loudspeaker using a shunt circuit through electro-mechanical coupling, which induces reactance with different signs from that of loudspeaker. An RLC shunt circuit is connected to the moving coil to provide an electrically induced mechanical impedance which counters the cavity stiffness at low frequencies and reduces the system inertia above the resonance frequency. A sound absorption coefficient well above 0.5 is demonstrated across frequencies between 150 and 1200 Hz. The performance of the proposed device is superior to existing passive absorbers of the same depth (60 mm), which has lower frequency limits of around 300 Hz. A passive noise absorber is further proposed by paralleling a micro-perforated panel with shunted loudspeaker which shows potentials in absorbing band-limit impulse noise.

  6. Nonequilibrium dynamics of active matter with correlated noise: A dynamical renormalization group study

    Science.gov (United States)

    Kachan, Devin; Levine, Alex; Bruinsma, Robijn

    2014-03-01

    Biology is rife with examples of active materials - soft matter systems driven into nonequilibrium steady states by energy input at the micro scale. For example, solutions of active micron scale swimmers produce active fluids showing phenomena reminiscent of turbulent convection at low Reynolds number; cytoskeletal networks driven by endogenous molecular motors produce active solids whose mechanics and low frequency strain fluctuations depend sensitively on motor activity. One hallmark of these systems is that they are driven at the micro scale by temporally correlated forces. In this talk, we study how correlated noise at the micro scale leads to novel long wavelength and long time scale dynamics at the macro scale in a simple model system. Specifically, we study the fluctuations of a ϕ4 scalar field obeying model A dynamics and driven by noise with a finite correlation time τ. We show that the effective dynamical system at long length and time scales is driven by white noise with a renormalized amplitude and renormalized transport coefficients. We discuss the implications of this result for a broad class of active matter systems driven at the micro scale by colored noise.

  7. AN ADAPTIVE OPTIMAL KALMAN FILTER FOR STOCHASTIC VIBRATION CONTROL SYSTEM WITH UNKNOWN NOISE VARIANCES

    Institute of Scientific and Technical Information of China (English)

    Li Shu; Zhuo Jiashou; Ren Qingwen

    2000-01-01

    In this paper, an optimal criterion is presented for adaptive Kalman filter in a control sys tem with unknown variances of stochastic vibration by constructing a function of noise variances and minimizing the function. We solve the model and measure variances by using DFP optimal method to guarantee the results of Kalman filter to be optimized. Finally, the control of vibration can be implemented by LQG method.

  8. The Effect of Background Noise on the Word Activation Process in Nonnative Spoken-Word Recognition.

    Science.gov (United States)

    Scharenborg, Odette; Coumans, Juul M J; van Hout, Roeland

    2017-08-07

    This article investigates 2 questions: (1) does the presence of background noise lead to a differential increase in the number of simultaneously activated candidate words in native and nonnative listening? And (2) do individual differences in listeners' cognitive and linguistic abilities explain the differential effect of background noise on (non-)native speech recognition? English and Dutch students participated in an English word recognition experiment, in which either a word's onset or offset was masked by noise. The native listeners outperformed the nonnative listeners in all listening conditions. Importantly, however, the effect of noise on the multiple activation process was found to be remarkably similar in native and nonnative listening. The presence of noise increased the set of candidate words considered for recognition in both native and nonnative listening. The results indicate that the observed performance differences between the English and Dutch listeners should not be primarily attributed to a differential effect of noise, but rather to the difference between native and nonnative listening. Additional analyses showed that word-initial information was found to be more important than word-final information during spoken-word recognition. When word-initial information was no longer reliably available word recognition accuracy dropped and word frequency information could no longer be used suggesting that word frequency information is strongly tied to the onset of words and the earliest moments of lexical access. Proficiency and inhibition ability were found to influence nonnative spoken-word recognition in noise, with a higher proficiency in the nonnative language and worse inhibition ability leading to improved recognition performance. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  9. A low-phase-noise digitally controlled crystal oscillator for DVB TV tuners

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Wei; Lu Lei; Tang Zhangwen, E-mail: zwtang@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2010-07-15

    This paper presents a 25-MHz fully-integrated digitally controlled crystal oscillator (DCXO) with automatic amplitude control (AAC). The DCXO is based on Colpitts topology for one-pin solution. The AAC circuit is introduced to optimize the phase noise performance. The automatic frequency control is realized by a 10-bit thermometer-code segmental tapered MOS capacitor array, ensuring a {approx} 35 ppm tuning range and {approx} 0.04 ppm frequency step. The measured phase noise results are -139 dBc/Hz at 1 kHz and -151 dBc/Hz at 10 kHz frequency offset, respectively. The chip consumes 1 mA at 1.8V supply and occupies 0.4 mm{sup 2} in a 0.18-{mu}m CMOS process.

  10. A low-phase-noise digitally controlled crystal oscillator for DVB TV tuners

    Science.gov (United States)

    Wei, Zhao; Lei, Lu; Zhangwen, Tang

    2010-07-01

    This paper presents a 25-MHz fully-integrated digitally controlled crystal oscillator (DCXO) with automatic amplitude control (AAC). The DCXO is based on Colpitts topology for one-pin solution. The AAC circuit is introduced to optimize the phase noise performance. The automatic frequency control is realized by a 10-bit thermometer-code segmental tapered MOS capacitor array, ensuring a ~ 35 ppm tuning range and ~ 0.04 ppm frequency step. The measured phase noise results are -139 dBc/Hz at 1 kHz and -151 dBc/Hz at 10 kHz frequency offset, respectively. The chip consumes 1 mA at 1.8V supply and occupies 0.4 mm2 in a 0.18-μm CMOS process.

  11. Numerical simulation of tandem-cylinder noise-reduction using plasma-based flow control

    Science.gov (United States)

    Wang, Meng; Eltaweel, Ahmed; Thomas, Flint; Kozlov, Alexey; Kim, Dongjoo

    2011-11-01

    The noise of low-Mach-number flow over tandem cylinders at ReD = 22 , 000 and its reduction using plasma actuators are simulated numerically to confirm and extend earlier experimental results. The numerical approach is based on large-eddy simulation for the turbulent flow field, a semi-empirical plasma actuation model, and Lighthill's theory for acoustic calculation. Excellent agreement between LES and experimental results is obtained for both the baseline flow and flow with plasma control in terms of wake velocity profiles, turbulence intensity, and frequency spectra of pressure fluctuations on the downstream cylinder. The validated flow-field results allow an accurate acoustic analysis based on Lighthill's equation, which is solved using a boundary-element method. The effectiveness of plasma actuators for reducing noise is demonstrated. In the baseline flow, the acoustic field is dominated by the interaction of the downstream cylinder with the upstream wake. With flow control the interaction noise is reduced drastically through suppression of vortex shedding from the upstream cylinder, and the vortex-shedding noise from the downstream cylinder becomes dominant. The peak sound pressure level is reduced by approximately 15 dB. Supported by NASA Cooperative Agreement NNX07AO09A.

  12. Noise-based body-wave seismic tomography in an active underground mine.

    Science.gov (United States)

    Olivier, G.; Brenguier, F.; Campillo, M.; Lynch, R.; Roux, P.

    2014-12-01

    Over the last decade, ambient noise tomography has become increasingly popular to image the earth's upper crust. The seismic noise recorded in the earth's crust is dominated by surface waves emanating from the interaction of the ocean with the solid earth. These surface waves are low frequency in nature ( noise recorded at higher frequencies are typically from anthropogenic sources, which are short lived, spatially unstable and not well suited for constructing seismic Green's functions between sensors with conventional cross-correlation methods. To examine the use of ambient noise tomography for smaller scale applications, continuous data were recorded for 5 months in an active underground mine in Sweden located more than 1km below surface with 18 high frequency seismic sensors. A wide variety of broadband (10 - 3000 Hz) seismic noise sources are present in an active underground mine ranging from drilling, scraping, trucks, ore crushers and ventilation fans. Some of these sources generate favorable seismic noise, while others are peaked in frequency and not usable. In this presentation, I will show that the noise generated by mining activity can be useful if periods of seismic noise are carefully selected. Although noise sources are not temporally stable and not evenly distributed around the sensor array, good estimates of the seismic Green's functions between sensors can be retrieved for a broad frequency range (20 - 400 Hz) when a selective stacking scheme is used. For frequencies below 100 Hz, the reconstructed Green's functions show clear body-wave arrivals for almost all of the 153 sensor pairs. The arrival times of these body-waves are picked and used to image the local velocity structure. The resulting 3-dimensional image shows a high velocity structure that overlaps with a known ore-body. The material properties of the ore-body differ from the host rock and is likely the cause of the observed high velocity structure. For frequencies above 200 Hz, the

  13. Synchronization of uncertain chaotic systems using active sliding mode control

    Energy Technology Data Exchange (ETDEWEB)

    Haeri, Mohammad [Advanced Control System Lab, Electrical Engineering Department, Sharif University of Technology, Azadi Avenue, 11365-9363 Tehran (Iran, Islamic Republic of)]. E-mail: haeri@sina.sharif.edu; Tavazoei, Mohammad Saleh [Advanced Control System Lab, Electrical Engineering Department, Sharif University of Technology, Azadi Avenue, 11365-9363 Tehran (Iran, Islamic Republic of); Naseh, Majid Reza [Electrical Engineering Department, Islamic Azad University of Birjand, Birjand (Iran, Islamic Republic of)

    2007-08-15

    We apply the active sliding mode controller to synchronize two uncertain chaotic systems. Uncertainties are considered both in linear and nonlinear parts of the system dynamics. We have also studied the case that the signals are contaminated by measuring channel noise. It is shown that having some conditions on the uncertainties and noise magnitude, the closed loop stability can be guaranteed. The synchronization errors are shown to be confined into some bounded value. Numerical simulations are presented to evaluate the analysis and effectiveness of the controller.

  14. Control and Synchronization of Chaos in RCL-Shunted Josephson Junction with Noise Disturbance Using Only One Controller Term

    Directory of Open Access Journals (Sweden)

    Di-Yi Chen

    2012-01-01

    Full Text Available This paper investigates the control and synchronization of the shunted nonlinear resistive-capacitive-inductance junction (RCLSJ model under the condition of noise disturbance with only one single controller. Based on the sliding mode control method, the controller is designed to eliminate the chaotic behavior of Josephson junctions and realize the achievement of global asymptotic synchronization of coupled system. Numerical simulation results are presented to demonstrate the validity of the proposed method. The approach is simple and easy to implement and provides reference for chaos control and synchronization in relevant systems.

  15. Improved PHIP polarization using a precision, low noise, voltage controlled current source

    Science.gov (United States)

    Agraz, Jose; Grunfeld, Alexander; Cunningham, Karl; Li, Debiao; Wagner, Shawn

    2013-10-01

    Existing para-hydrogen induced polarization (PHIP) instrumentation relies on magnetic fields to hyperpolarize substances. These hyperpolarized substances have enhanced magnetic resonance imaging (MRI) signals over 10,000 fold, allowing for MRI at the molecular level. Required magnetic fields are generated by energizing a solenoid coil with current produced by a voltage controlled voltage source (VCVS), also known as a power supply. A VCVS lacks the current regulation necessary to keep magnetic field fluctuations to a minimum, which results in low PHIP polarization. A voltage controlled current source (VCCS) is an electric circuit that generates a steady flow of electrons proportional to an input voltage. A low noise VCCS provides the solenoid current flow regulation necessary to generate a stable static magnetic field (Bo). We discuss the design and implementation of a low noise, high stability, VCCS for magnetic field generation with minimum variations. We show that a precision, low noise, voltage reference driving a metal oxide semiconductor field effect transistor (MOSFET) based current sink, results in the current flow control necessary for generating a low noise and high stability Bo. In addition, this work: (1) compares current stability for ideal VCVS and VCCS models using transfer functions (TF), (2) develops our VCCS design's TF, (3) measures our VCCS design's thermal & 1/f noise, and (4) measures and compares hydroxyethyl-propionate (HEP) polarization obtained using a VCVS and our VCCS. The hyperpolarization of HEP was done using a PHIP instrument developed in our lab. Using our VCCS design, HEP polarization magnitude data show a statistically significant increase in polarization over using a VCVS. Circuit schematic, bill of materials, board layout, TF derivation, and Matlab simulations code are included as supplemental files.

  16. Improved PHIP polarization using a precision, low noise, voltage controlled current source.

    Science.gov (United States)

    Agraz, Jose; Grunfeld, Alexander; Cunningham, Karl; Li, Debiao; Wagner, Shawn

    2013-10-01

    Existing para-hydrogen induced polarization (PHIP) instrumentation relies on magnetic fields to hyperpolarize substances. These hyperpolarized substances have enhanced magnetic resonance imaging (MRI) signals over 10,000 fold, allowing for MRI at the molecular level. Required magnetic fields are generated by energizing a solenoid coil with current produced by a voltage controlled voltage source (VCVS), also known as a power supply. A VCVS lacks the current regulation necessary to keep magnetic field fluctuations to a minimum, which results in low PHIP polarization. A voltage controlled current source (VCCS) is an electric circuit that generates a steady flow of electrons proportional to an input voltage. A low noise VCCS provides the solenoid current flow regulation necessary to generate a stable static magnetic field (Bo). We discuss the design and implementation of a low noise, high stability, VCCS for magnetic field generation with minimum variations. We show that a precision, low noise, voltage reference driving a metal oxide semiconductor field effect transistor (MOSFET) based current sink, results in the current flow control necessary for generating a low noise and high stability Bo. In addition, this work: (1) compares current stability for ideal VCVS and VCCS models using transfer functions (TF), (2) develops our VCCS design's TF, (3) measures our VCCS design's thermal & 1/f noise, and (4) measures and compares hydroxyethyl-propionate (HEP) polarization obtained using a VCVS and our VCCS. The hyperpolarization of HEP was done using a PHIP instrument developed in our lab. Using our VCCS design, HEP polarization magnitude data show a statistically significant increase in polarization over using a VCVS. Circuit schematic, bill of materials, board layout, TF derivation, and Matlab simulations code are included as supplemental files.

  17. Feedforward control of sound transmission using an active acoustic metamaterial

    Science.gov (United States)

    Cheer, Jordan; Daley, Stephen; McCormick, Cameron

    2017-02-01

    Metamaterials have received significant interest in recent years due to their potential ability to exhibit behaviour not found in naturally occurring materials. This includes the generation of band gaps, which are frequency regions with high levels of wave attenuation. In the context of acoustics, these band gaps can be tuned to occur at low frequencies where the acoustic wavelength is large compared to the material, and where the performance of traditional passive noise control treatments is limited. Therefore, such acoustic metamaterials have been shown to offer a significant performance advantage compared to traditional passive control treatments, however, due to their resonant behaviour, the band gaps tend to occur over a relatively narrow frequency range. A similar long wavelength performance advantage can be achieved using active noise control, but the systems in this case do not rely on resonant behaviour. This paper demonstrates how the performance of an acoustic metamaterial, consisting of an array of Helmholtz resonators, can be significantly enhanced by the integration of an active control mechanism that is facilitated by embedding loudspeakers into the resonators. Crucially, it is then also shown how the active acoustic metamaterial significantly outperforms an equivalent traditional active noise control system. In both cases a broadband feedforward control strategy is employed to minimise the transmitted pressure in a one-dimensional acoustic control problem and a new method of weighting the control effort over a targeted frequency range is described.

  18. Active control of convection

    Energy Technology Data Exchange (ETDEWEB)

    Bau, H.H. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    1995-12-31

    Using stability theory, numerical simulations, and in some instances experiments, it is demonstrated that the critical Rayleigh number for the bifurcation (1) from the no-motion (conduction) state to the motion state and (2) from time-independent convection to time-dependent, oscillatory convection in the thermal convection loop and Rayleigh-Benard problems can be significantly increased or decreased. This is accomplished through the use of a feedback controller effectuating small perturbations in the boundary data. The controller consists of sensors which detect deviations in the fluid`s temperature from the motionless, conductive values and then direct actuators to respond to these deviations in such a way as to suppress the naturally occurring flow instabilities. Actuators which modify the boundary`s temperature/heat flux are considered. The feedback controller can also be used to control flow patterns and generate complex dynamic behavior at relatively low Rayleigh numbers.

  19. Applied acoustics concepts, absorbers, and silencers for acoustical comfort and noise control alternative solutions, innovative tools, practical examples

    CERN Document Server

    Fuchs, Helmut V

    2013-01-01

    The author gives a comprehensive overview of materials and components for noise control and acoustical comfort. Sound absorbers must meet acoustical and architectural requirements, which fibrous or porous material alone can meet. Basics and applications are demonstrated, with representative examples for spatial acoustics, free-field test facilities and canal linings. Acoustic engineers and construction professionals will find some new basic concepts and tools for developments in order to improve acoustical comfort. Interference absorbers, active resonators and micro-perforated absorbers of different materials and designs complete the list of applications.

  20. Speech recognition in noise with active and passive hearing protectors: a comparative study.

    Science.gov (United States)

    Bockstael, Annelies; De Coensel, Bert; Botteldooren, Dick; D'Haenens, Wendy; Keppler, Hannah; Maes, Leen; Philips, Birgit; Swinnen, Freya; Bart, Vinck

    2011-06-01

    The perceived negative influence of standard hearing protectors on communication is a common argument for not wearing them. Thus, "augmented" protectors have been developed to improve speech intelligibility. Nevertheless, their actual benefit remains a point of concern. In this paper, speech perception with active earplugs is compared to standard passive custom-made earplugs. The two types of active protectors included amplify the incoming sound with a fixed level or to a user selected fraction of the maximum safe level. For the latter type, minimal and maximal amplification are selected. To compare speech intelligibility, 20 different speech-in-noise fragments are presented to 60 normal-hearing subjects and speech recognition is scored. The background noise is selected from realistic industrial noise samples with different intensity, frequency, and temporal characteristics. Statistical analyses suggest that the protectors' performance strongly depends on the noise condition. The active protectors with minimal amplification outclass the others for the most difficult and the easiest situations, but they also limit binaural listening. In other conditions, the passive protectors clearly surpass their active counterparts. Subsequently, test fragments are analyzed acoustically to clarify the results. This provides useful information for developing prototypes, but also indicates that tests with human subjects remain essential. © 2011 Acoustical Society of America

  1. Subjective Listening Effort and Electrodermal Activity in Listening Situations with Reverberation and Noise

    Science.gov (United States)

    Haeder, Kristina; Imbery, Christina; Weber, Reinhard

    2016-01-01

    Disturbing factors like reverberation or ambient noise can impair speech recognition and raise the listening effort needed for successful communication in daily life. Situations with high listening effort are thought to result in increased stress for the listener. The aim of this study was to explore possible measures to determine listening effort in situations with varying background noise and reverberation. For this purpose, subjective ratings of listening effort, speech recognition, and stress level, together with the electrodermal activity as a measure of the autonomic stress reaction, were investigated. It was expected that the electrodermal activity would show different stress levels in different acoustic situations and might serve as an alternative to subjective ratings. Ten young normal-hearing and 17 elderly hearing-impaired subjects listened to sentences from the Oldenburg sentence test either with stationary background noise or with reverberation. Four listening situations were generated, an easy and a hard one for each of the two disturbing factors, which were related to each other by the Speech Transmission Index. The easy situation resulted in 100% and the hard situation resulted in 30 to 80% speech recognition. The results of the subjective ratings showed significant differences between the easy and the hard listening situations in both subject groups. Two methods of analyzing the electrodermal activity values revealed similar, but nonsignificant trends. Significant correlations between subjective ratings and physiological electrodermal activity data were observed for normal-hearing subjects in the noise situation. PMID:27698257

  2. Sound Control in the Physic Lab in the Polyacryl Company and Studying the Noise Reduction by Means of Different Absorbents

    Directory of Open Access Journals (Sweden)

    Harandi

    1999-03-01

    Full Text Available Studying noise effect at the workplace has more various aspects than other factors. So it is not surprising that its adverse impact on the physical and mental state of the society has been detected to some extent. There is a significant correlation between the hearing loss and the noise pollution of the workplaces. The most important ways to lessen and control the impact of noise are: substituting the noisy equipments with ones that produce less noise, correcting noise sources and isolating the sound source. In the current study we tried to control the noise level by using various sound absorbents and measured sound level by using these different substances. The results of these measurements have reported in the current article in details.

  3. Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

    NARCIS (Netherlands)

    Ho, J.H.; Berkhoff, A.P.

    2014-01-01

    This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of

  4. Active Combustion Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past decade, research into active combustion control has yielded impressive results in suppressing thermoacoustic instabilities and widening the...

  5. Active Combustion Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past decade, research into active combustion control has yielded impressive results in suppressing thermoacoustic instabilities and widening the operational...

  6. Experimental active control of sound in the ATR 42

    Science.gov (United States)

    Paonessa, A.; Sollo, A.; Paxton, M.; Purver, M.; Ross, C. F.

    Passenger comfort is becoming day by day an important issue for the market of the regional turboprop aircraft and also for the future high speed propeller driven aircraft. In these aircraft the main contribution to the passenger annoyance is due to the propeller noise blade passing frequency (BPF) and its harmonics. In the recent past a detailed theoretical and experimental work has been done by Alenia Aeronautica in order to reduce the noise level in the ATR aircraft passenger cabin by means of conventional passive treatments: synchrophasing of propellers, dynamic vibration absorbers, structural reinforcements, damping materials. The application of these treatments has been introduced on production aircraft with a remarkable improvement of noise comfort but with a significant weight increase. For these reasons, a major technology step is required for reaching passenger comfort comparable to that of jet aircraft with the minimum weight increase. The most suitable approach to this problem has been envisaged in the active noise control which consists in generating an anti-sound field in the passenger cabin to reduce the noise at propeller BPF and its harmonics. The attenuation is reached by means of a control system which acquires information about the cabin noise distribution and the propeller speed during flight and simultaneously generates the signals to drive the speakers.

  7. Reduction of Helicopter BVI Noise, Vibration, and Power Consumption Through Individual Blade Control

    Science.gov (United States)

    Jacklin, Stephen A.; Blaas, Achim; Teves, Dietrich; Kube, Roland; Warmbrodt, William (Technical Monitor)

    1994-01-01

    A wind tunnel test was conducted with a full-scale BO 105 helicopter rotor to evaluate the potential of open-loop individual blade control (IBC) to improve rotor performance, to reduce blade vortex interaction (BVI) noise, and to alleviate helicopter vibrations. The wind tunnel test was an international collaborative effort between NASA/U.S. Army AFDD, ZF Luftfahrttechnik, Eurocopter Deutschland, and the German Aerospace Laboratory (DLR) and was conducted under the auspices of the U.S./German MOU on Rotorcraft Aeromechanics. In this test the normal blade pitch links of the rotor were replaced by servo-actuators so that the pitch of each blade could be controlled independently of the other blades. The specially designed servoactuators and IBC control system were designed and manufactured by ZF Luftfahrttechnik, GmbH. The wind tunnel test was conducted in the 40- by 80-Foot Wind Tunnel at the NASA Ames Research Center. An extensive amount of measurement information was acquired for each IBC data point. These data include rotor performance, static and dynamic hub forces and moments, rotor loads, control loads, inboard and outboard blade pitch motion, and BVI noise data. The data indicated very significant (80 percent) simultaneous reductions in both BVI noise and hub vibrations could be obtained using multi-harmonic input at the critical descent (terminal approach) condition. The data also showed that performance improvements of up to 7 percent could be obtained using 2P input at high-speed forward flight conditions.

  8. Stochastic optimal control and estimation methods adapted to the noise characteristics of the sensorimotor system.

    Science.gov (United States)

    Todorov, Emanuel

    2005-05-01

    Optimality principles of biological movement are conceptually appealing and straightforward to formulate. Testing them empirically, however, requires the solution to stochastic optimal control and estimation problems for reasonably realistic models of the motor task and the sensorimotor periphery. Recent studies have highlighted the importance of incorporating biologically plausible noise into such models. Here we extend the linear-quadratic-gaussian framework--currently the only framework where such problems can be solved efficiently--to include control-dependent, state-dependent, and internal noise. Under this extended noise model, we derive a coordinate-descent algorithm guaranteed to converge to a feedback control law and a nonadaptive linear estimator optimal with respect to each other. Numerical simulations indicate that convergence is exponential, local minima do not exist, and the restriction to nonadaptive linear estimators has negligible effects in the control problems of interest. The application of the algorithm is illustrated in the context of reaching movements. A Matlab implementation is available at www.cogsci.ucsd.edu/~todorov.

  9. Reduction of Helicopter BVI Noise, Vibration, and Power Consumption Through Individual Blade Control

    Science.gov (United States)

    Jacklin, Stephen A.; Blaas, Achim; Teves, Dietrich; Kube, Roland; Warmbrodt, William (Technical Monitor)

    1994-01-01

    A wind tunnel test was conducted with a full-scale BO 105 helicopter rotor to evaluate the potential of open-loop individual blade control (IBC) to improve rotor performance, to reduce blade vortex interaction (BVI) noise, and to alleviate helicopter vibrations. The wind tunnel test was an international collaborative effort between NASA/U.S. Army AFDD, ZF Luftfahrttechnik, Eurocopter Deutschland, and the German Aerospace Laboratory (DLR) and was conducted under the auspices of the U.S./German MOU on Rotorcraft Aeromechanics. In this test the normal blade pitch links of the rotor were replaced by servo-actuators so that the pitch of each blade could be controlled independently of the other blades. The specially designed servoactuators and IBC control system were designed and manufactured by ZF Luftfahrttechnik, GmbH. The wind tunnel test was conducted in the 40- by 80-Foot Wind Tunnel at the NASA Ames Research Center. An extensive amount of measurement information was acquired for each IBC data point. These data include rotor performance, static and dynamic hub forces and moments, rotor loads, control loads, inboard and outboard blade pitch motion, and BVI noise data. The data indicated very significant (80 percent) simultaneous reductions in both BVI noise and hub vibrations could be obtained using multi-harmonic input at the critical descent (terminal approach) condition. The data also showed that performance improvements of up to 7 percent could be obtained using 2P input at high-speed forward flight conditions.

  10. Initial results of a model rotor higher harmonic control (HHC) wind tunnel experiment on BVI impulsive noise reduction

    Science.gov (United States)

    Splettstoesser, W. R.; Lehmann, G.; van der Wall, B.

    1989-09-01

    Initial acoustic results are presented from a higher harmonic control (HHC) wind tunnel pilot experiment on helicopter rotor blade-vortex interaction (BVI) impulsive noise reduction, making use of the DFVLR 40-percent-scaled BO-105 research rotor in the DNW 6m by 8m closed test section. Considerable noise reduction (of several decibels) has been measured for particular HHC control settings, however, at the cost of increased vibration levels and vice versa. The apparently adverse results for noise and vibration reduction by HHC are explained. At optimum pitch control settings for BVI noise reduction, rotor simulation results demonstrate that blade loading at the outer tip region is decreased, vortex strength and blade vortex miss-distance are increased, resulting altogether in reduced BVI noise generation. At optimum pitch control settings for vibration reduction adverse effects on blade loading, vortex strength and blade vortex miss-distance are found.

  11. Hot carrier effects on jitter and phase noise in CMOS voltage-controlled oscillators

    Science.gov (United States)

    Zhang, Chi; Srivastava, Ashok

    2005-05-01

    The effects of hot carrier stress on CMOS voltage-controlled oscillators (VCO) are investigated. A model of the threshold voltage degradation in MOSFETs due to hot carrier stress has been used to model jitter and phase noise in voltage-controlled oscillators. The relation between the stress time which induces the hot carrier effects and the degradation of the VCO performance is presented. The VCO performance degradation takes into consideration decrease in operation frequency, increase in jitter and phase noise and decrease in tuning range. The experimental circuits have been designed in 0.5 μm n-well CMOS technology for operation at 3 V. It is shown that when the MOSFET threshold voltage, increases from 0.4 V to 0.9 V due to the hot carrier effect, for the single-ended ring oscillator, the oscillation frequency changes from 538 MHz to 360 MHz, and the phase noise changes from -104 dBc to -105 dBc at 1 MHz frequency offset with a power dissipation of 0.37 mW. For the current-starved VCO, the tuning range changes from 72 MHz - 287 MHz to 65.4 MHz - 201 MHz, and the phase noise changes from -109 dBc to -107 dBc at 1 MHz offset from the center frequency, 200 MHz; for the double-ended differential VCO, the tuning range changes from 32 MHz - 983 MHz to 26 MHz - 698 MHz, and phase noise changes from -86 dBc to -87 dBc at 1 MHz offset from the center frequency, 700 MHz.

  12. Active self-testing noise measurement sensors for large-scale environmental sensor networks.

    Science.gov (United States)

    Domínguez, Federico; Cuong, Nguyen The; Reinoso, Felipe; Touhafi, Abdellah; Steenhaut, Kris

    2013-12-13

    Large-scale noise pollution sensor networks consist of hundreds of spatially distributed microphones that measure environmental noise. These networks provide historical and real-time environmental data to citizens and decision makers and are therefore a key technology to steer environmental policy. However, the high cost of certified environmental microphone sensors render large-scale environmental networks prohibitively expensive. Several environmental network projects have started using off-the-shelf low-cost microphone sensors to reduce their costs, but these sensors have higher failure rates and produce lower quality data. To offset this disadvantage, we developed a low-cost noise sensor that actively checks its condition and indirectly the integrity of the data it produces. The main design concept is to embed a 13 mm speaker in the noise sensor casing and, by regularly scheduling a frequency sweep, estimate the evolution of the microphone's frequency response over time. This paper presents our noise sensor's hardware and software design together with the results of a test deployment in a large-scale environmental network in Belgium. Our middle-range-value sensor (around €50) effectively detected all experienced malfunctions, in laboratory tests and outdoor deployments, with a few false positives. Future improvements could further lower the cost of our sensor below €10.

  13. Active Self-Testing Noise Measurement Sensors for Large-Scale Environmental Sensor Networks

    Directory of Open Access Journals (Sweden)

    Federico Domínguez

    2013-12-01

    Full Text Available Large-scale noise pollution sensor networks consist of hundreds of spatially distributed microphones that measure environmental noise. These networks provide historical and real-time environmental data to citizens and decision makers and are therefore a key technology to steer environmental policy. However, the high cost of certified environmental microphone sensors render large-scale environmental networks prohibitively expensive. Several environmental network projects have started using off-the-shelf low-cost microphone sensors to reduce their costs, but these sensors have higher failure rates and produce lower quality data. To offset this disadvantage, we developed a low-cost noise sensor that actively checks its condition and indirectly the integrity of the data it produces. The main design concept is to embed a 13 mm speaker in the noise sensor casing and, by regularly scheduling a frequency sweep, estimate the evolution of the microphone’s frequency response over time. This paper presents our noise sensor’s hardware and software design together with the results of a test deployment in a large-scale environmental network in Belgium. Our middle-range-value sensor (around €50 effectively detected all experienced malfunctions, in laboratory tests and outdoor deployments, with a few false positives. Future improvements could further lower the cost of our sensor below €10.

  14. Observer-Based Controller Design for Singular Stochastic Markov Jump Systems with State Dependent Noise

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yong; ZHANG Weihai

    2016-01-01

    This paper is concerned with the problem of observer-based controller design for singular stochastic Markov jump systems with state-dependent noise.Two concepts called "non-impulsiveness" and "mean square admissibility" are introduced,which are different from previous ones.Sufficient conditions for the open-and closed-loop singular stochastic Markov jump systems with state-dependent noise to be mean square admissible are provided in terms of strict LMIs.The controller gain and the observer gain which guarantee the resulting closed-loop error system to be mean square admissible are obtained in turn by solving the strict LMIs.A numerical example is presented to show the efficiency of the design approach.

  15. Odeon, a design tool for auditorium acoustics, noise control and loudspeaker systems

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge

    2001-01-01

    The ODEON software was originally developed for prediction of auditorium acoustics. However current editions of the software are not limited to these fields, but also allow prediction in rooms such as churches and mosques, interior noise control, design of room acoustics and sound distribution...... systems in public rooms such as foyers, underground stations and airports. Some of the features in ODEON 5.0 Combined are; two methods for global estimation of reverberation time, various point response calculations providing decay curves, reflectograms, miscellaneous parameter graphs, 3D maps, multi......-source calculations including point, line and surface sources, facilities for noise control calculations and multi-channel auralization using fully filtered BRIR’s....

  16. Acute and Long-Term Effects of Noise Exposure on the Neuronal Spontaneous Activity in Cochlear Nucleus and Inferior Colliculus Brain Slices

    Directory of Open Access Journals (Sweden)

    Moritz Gröschel

    2014-01-01

    Full Text Available Noise exposure leads to an immediate hearing loss and is followed by a long-lasting permanent threshold shift, accompanied by changes of cellular properties within the central auditory pathway. Electrophysiological recordings have demonstrated an upregulation of spontaneous neuronal activity. It is still discussed if the observed effects are related to changes of peripheral input or evoked within the central auditory system. The present study should describe the intrinsic temporal patterns of single-unit activity upon noise-induced hearing loss of the dorsal and ventral cochlear nucleus (DCN and VCN and the inferior colliculus (IC in adult mouse brain slices. Recordings showed a slight, but significant, elevation in spontaneous firing rates in DCN and VCN immediately after noise trauma, whereas no differences were found in IC. One week postexposure, neuronal responses remained unchanged compared to controls. At 14 days after noise trauma, intrinsic long-term hyperactivity in brain slices of the DCN and the IC was detected for the first time. Therefore, increase in spontaneous activity seems to develop within the period of two weeks, but not before day 7. The results give insight into the complex temporal neurophysiological alterations after noise trauma, leading to a better understanding of central mechanisms in noise-induced hearing loss.

  17. Acute and long-term effects of noise exposure on the neuronal spontaneous activity in cochlear nucleus and inferior colliculus brain slices.

    Science.gov (United States)

    Gröschel, Moritz; Ryll, Jana; Götze, Romy; Ernst, Arne; Basta, Dietmar

    2014-01-01

    Noise exposure leads to an immediate hearing loss and is followed by a long-lasting permanent threshold shift, accompanied by changes of cellular properties within the central auditory pathway. Electrophysiological recordings have demonstrated an upregulation of spontaneous neuronal activity. It is still discussed if the observed effects are related to changes of peripheral input or evoked within the central auditory system. The present study should describe the intrinsic temporal patterns of single-unit activity upon noise-induced hearing loss of the dorsal and ventral cochlear nucleus (DCN and VCN) and the inferior colliculus (IC) in adult mouse brain slices. Recordings showed a slight, but significant, elevation in spontaneous firing rates in DCN and VCN immediately after noise trauma, whereas no differences were found in IC. One week postexposure, neuronal responses remained unchanged compared to controls. At 14 days after noise trauma, intrinsic long-term hyperactivity in brain slices of the DCN and the IC was detected for the first time. Therefore, increase in spontaneous activity seems to develop within the period of two weeks, but not before day 7. The results give insight into the complex temporal neurophysiological alterations after noise trauma, leading to a better understanding of central mechanisms in noise-induced hearing loss.

  18. Stability analysis of a noise control system in a duct by using delay differential equation

    Institute of Scientific and Technical Information of China (English)

    Masakazu Haraguchi; Hai Yan Hu

    2009-01-01

    The paper deals with the criteria for the closed-loop stability of a noise control system in a duct. To study the stability of the system, the model of delay differential equation is derived from the propagation of acoustic wave governed by a partial differential equation of hyperbolic type. Then, a simple feedback controller is designed, and its closed-loop stability is analyzed on the basis of the derived model of delay differential equation. The obtained criteria reveal the influence of the controller gain and the positions of a sensor and an actuator on the closed-loop stability. Finally, numerical simulations are presented to support the theoreti-cal results.

  19. Comparison of Gap in Noise Test Results in Musicians and Non-Musician Controls

    OpenAIRE

    Ghassem Mohamadkhani; Mohammad Hossein Nilforoushkhoshk; Ali Zadeh Mohammadi; Soghrat Faghihzadeh; Mahsa Sepehrnejhad

    2011-01-01

    Background and Aim: Main feature of auditory processing abilities is temporal processing including temporal resolution, temporal ordering, temporal integration and temporal masking. Many studies have shown the superiority of musicians in temporal discrimination over non-musicians. In this study we compared temporal processing in musicians and non-musician controls via Gap in Noise (GIN) test.Methods: This cohort study was conducted on 24 musicians with mean age of 25.3 years and 24 normal hea...

  20. Noise Parameters of CW Radar Sensors Used in Active Defense Systems

    OpenAIRE

    2012-01-01

    Active defense represents an innovative way of protecting military vehicles. It is based on the employment of a set of radar sensors which detect an approaching threat missile and activate a suitable counter-measure. Since the radar sensors are supposed to detect flying missiles very fast and, at the same time, distinguish them from stationary or slow-moving objects, CW Doppler radar sensors can be employed with a benefit. The submitted article deals with a complex noise analysis of this type...

  1. Comparison of Auditory Brainstem Response in Noise Induced Tinnitus and Non-Tinnitus Control Subjects

    Directory of Open Access Journals (Sweden)

    Ghassem Mohammadkhani

    2009-12-01

    Full Text Available Background and Aim: Tinnitus is an unpleasant sound which can cause some behavioral disorders. According to evidence the origin of tinnitus is not only in peripheral but also in central auditory system. So evaluation of central auditory system function is necessary. In this study Auditory brainstem responses (ABR were compared in noise induced tinnitus and non-tinnitus control subjects.Materials and Methods: This cross-sectional, descriptive and analytic study is conducted in 60 cases in two groups including of 30 noise induced tinnitus and 30 non-tinnitus control subjects. ABRs were recorded ipsilateraly and contralateraly and their latencies and amplitudes were analyzed.Results: Mean interpeak latencies of III-V (p= 0.022, I-V (p=0.033 in ipsilatral electrode array and mean absolute latencies of IV (p=0.015 and V (p=0.048 in contralatral electrode array were significantly increased in noise induced tinnitus group relative to control group. Conclusion: It can be concluded from that there are some decrease in neural transmission time in brainstem and there are some sign of involvement of medial nuclei in olivery complex in addition to lateral lemniscus.

  2. Active Control of Suspension Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

  3. Noise Analysis and Control for Mobile Medical Compartment%机动医疗车辆舱室噪声分析及控制

    Institute of Scientific and Technical Information of China (English)

    武磊; 刘志国

    2011-01-01

    A large amount of mechanical and electrical equipment are used for improving the function of mobile medical compartment, and the complex HVAC system are designed for improving the comfortability of the compartment. So the noise level may be decreased. It may induce the efficiency decreasing and hearing loss of medical personal. It is important to control the noise level in system engineering designed for medical compartment. Active and passive noise control methods are used in device selecting, structure designing, new isolated material using and noise maintaining. Hearing protection devices are recommended for crew in high noise environment remote monitoring is used for decreasing time exposure to noise. The noise level in mobile medical comppartment reaches standard for effective noise eontrol, so hearing injury and disability payment losing decreased.[Chinese Medical Equipment Journal , 2011 , 32 ( 4) : 84-86]%以系统工程设计的思想,从设备选型、结构设计、降噪材料选用和降噪维护等环节上,采取主动、被动噪声控制方法降低舱室噪声,并用遥控等技术减少工作人员噪声暴露.建议高噪声暴露人员佩戴个人听力防护设备,指出过强的噪声降低医护人员的工作效率,损害医护人员和伤员听力,需要深入开展舱室噪声控制研究.

  4. A bulk-controlled ring-VCO with 1/f-noise reduction for frequency ΔΣ modulator

    DEFF Research Database (Denmark)

    Tuan Vu, CAO; Wisland, Dag T.; Lande, Tor Sverre

    The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub...

  5. Intrinsic Noise Profoundly Alters the Dynamics and Steady State of Morphogen-Controlled Bistable Genetic Switches.

    Directory of Open Access Journals (Sweden)

    Ruben Perez-Carrasco

    2016-10-01

    Full Text Available During tissue development, patterns of gene expression determine the spatial arrangement of cell types. In many cases, gradients of secreted signalling molecules-morphogens-guide this process by controlling downstream transcriptional networks. A mechanism commonly used in these networks to convert the continuous information provided by the gradient into discrete transitions between adjacent cell types is the genetic toggle switch, composed of cross-repressing transcriptional determinants. Previous analyses have emphasised the steady state output of these mechanisms. Here, we explore the dynamics of the toggle switch and use exact numerical simulations of the kinetic reactions, the corresponding Chemical Langevin Equation, and Minimum Action Path theory to establish a framework for studying the effect of gene expression noise on patterning time and boundary position. This provides insight into the time scale, gene expression trajectories and directionality of stochastic switching events between cell states. Taking gene expression noise into account predicts that the final boundary position of a morphogen-induced toggle switch, although robust to changes in the details of the noise, is distinct from that of the deterministic system. Moreover, the dramatic increase in patterning time close to the boundary predicted from the deterministic case is substantially reduced. The resulting stochastic switching introduces differences in patterning time along the morphogen gradient that result in a patterning wave propagating away from the morphogen source with a velocity determined by the intrinsic noise. The wave sharpens and slows as it advances and may never reach steady state in a biologically relevant time. This could explain experimentally observed dynamics of pattern formation. Together the analysis reveals the importance of dynamical transients for understanding morphogen-driven transcriptional networks and indicates that gene expression noise can

  6. Online identification of active absorbers in automotive vibration control

    Energy Technology Data Exchange (ETDEWEB)

    Buttelmann, M.; Lohmann, B.; Vinogradski, M.; Nedeljkovic, N. [Bremen Univ. (Germany). Inst. fuer Automatisierungstechnik; Marienfeld, P. [ContiTech Vibration Control GmbH, Hannover (Germany); Svaricek, F. [Continental Gummi-Werke AG, Hannover (Germany)

    2001-07-01

    In the past, engine-related noise and vibration in the vehicle cabin was exclusively reduced by passive absorption. Today, modern actuators and control systems make an active noise reduction possible by introducing counteracting vibration at 180 degrees phase lag. Within a cooperation of the Institute of Automation Systems and Continental AG, an approach using active absorbers at the engine mounts is investigated. As the dynamic behaviour of the active absorbers and other elements in the secondary path are time-variant (depending on temperature, age and other factors), an online identification is carried out. By this, the implemented feedforward control strategy is supported on a precise and frequently updated model of the secondary path. The chosen approaches to online and offline identification are presented together with first results achieved in online identification and with the overall control system. (orig.)

  7. Predicting the effect of urban noise on the active space of avian vocal signals.

    Science.gov (United States)

    Parris, Kirsten M; McCarthy, Michael A

    2013-10-01

    Urbanization changes the physical environment of nonhuman species but also markedly changes their acoustic environment. Urban noise interferes with acoustic communication in a range of animals, including birds, with potentially profound impacts on fitness. However, a mechanistic theory to predict which species of birds will be most affected by urban noise is lacking. We develop a mathematical model to predict the decrease in the active space of avian vocal signals after moving from quiet forest habitats to noisy urban habitats. We find that the magnitude of the decrease is largely a function of signal frequency. However, this relationship is not monotonic. A metaregression of observed increases in the frequency of birdsong in urban noise supports the model's predictions for signals with frequencies between 1.5 and 4 kHz. Using results of the metaregression and the model described above, we show that the expected gain in active space following observed frequency shifts is up to 12% and greatest for birds with signals at the lower end of this frequency range. Our generally applicable model, along with three predictions regarding the behavioral and population-level responses of birds to urban noise, represents an important step toward a theory of acoustic communication in urban habitats.

  8. An Engineering Approach to Management of Occupational and Community Noise Exposure at NASA Lewis Research Center

    Science.gov (United States)

    Cooper, Beth A.

    1997-01-01

    Workplace and environmental noise issues at NASA Lewis Research Center are effectively managed via a three-part program that addresses hearing conservation, community noise control, and noise control engineering. The Lewis Research Center Noise Exposure Management Program seeks to limit employee noise exposure and maintain community acceptance for critical research while actively pursuing engineered controls for noise generated by more than 100 separate research facilities and the associated services required for their operation.

  9. Diffusion dynamics in external noise-activated non-equilibrium open system-reservoir coupling environment

    Institute of Scientific and Technical Information of China (English)

    Wang Chun-Yang

    2013-01-01

    The diffusion process in an extemal noise-activated non-equilibrium open system-reservoir coupling environment is studied by analytically solving the generalized Langevin equation.The dynamical property of the system near the barrier top is investigated in detail by numerically calculating the quantities such as mean diffusion path,invariance,barrier passing probability,and so on.It is found that,comparing with the unfavorable effect of internal fluctuations,the external noise activation is sometimes beneficial to the diffusion process.An optimal strength of external activation or correlation time of the internal fluctuation is expected for the diffusing particle to have a maximal probability to escape from the potential well.

  10. Effects of image noise, respiratory motion, and motion compensation on 3D activity quantification in count-limited PET images

    Science.gov (United States)

    Siman, W.; Mawlawi, O. R.; Mikell, J. K.; Mourtada, F.; Kappadath, S. C.

    2017-01-01

    The aims of this study were to evaluate the effects of noise, motion blur, and motion compensation using quiescent-period gating (QPG) on the activity concentration (AC) distribution—quantified using the cumulative AC volume histogram (ACVH)—in count-limited studies such as 90Y-PET/CT. An International Electrotechnical Commission phantom filled with low 18F activity was used to simulate clinical 90Y-PET images. PET data were acquired using a GE-D690 when the phantom was static and subject to 1-4 cm periodic 1D motion. The static data were down-sampled into shorter durations to determine the effect of noise on ACVH. Motion-degraded PET data were sorted into multiple gates to assess the effect of motion and QPG on ACVH. Errors in ACVH at AC90 (minimum AC that covers 90% of the volume of interest (VOI)), AC80, and ACmean (average AC in the VOI) were characterized as a function of noise and amplitude before and after QPG. Scan-time reduction increased the apparent non-uniformity of sphere doses and the dispersion of ACVH. These effects were more pronounced in smaller spheres. Noise-related errors in ACVH at AC20 to AC70 were smaller (15%). The accuracy of ACmean was largely independent of the total count. Motion decreased the observed AC and skewed the ACVH toward lower values; the severity of this effect depended on motion amplitude and tumor diameter. The errors in AC20 to AC80 for the 17 mm sphere were  -25% and  -55% for motion amplitudes of 2 cm and 4 cm, respectively. With QPG, the errors in AC20 to AC80 of the 17 mm sphere were reduced to  -15% for motion amplitudes  0.5, QPG was effective at reducing errors in ACVH despite increases in image non-uniformity due to increased noise. ACVH is believed to be more relevant than mean or maximum AC to calculate tumor control and normal tissue complication probability. However, caution needs to be exercised when using ACVH in post-therapy 90Y imaging because of its susceptibility to image

  11. Automaticity or active control

    DEFF Research Database (Denmark)

    Tudoran, Ana Alina; Olsen, Svein Ottar

    This study addresses the quasi-moderating role of habit strength in explaining action loyalty. A model of loyalty behaviour is proposed that extends the traditional satisfaction–intention–action loyalty network. Habit strength is conceptualised as a cognitive construct to refer to the psychologic......, respectively, between intended loyalty and action loyalty. At high levels of habit strength, consumers are more likely to free up cognitive resources and incline the balance from controlled to routine and automatic-like responses.......This study addresses the quasi-moderating role of habit strength in explaining action loyalty. A model of loyalty behaviour is proposed that extends the traditional satisfaction–intention–action loyalty network. Habit strength is conceptualised as a cognitive construct to refer to the psychological...... aspects of the construct, such as routine, inertia, automaticity, or very little conscious deliberation. The data consist of 2962 consumers participating in a large European survey. The results show that habit strength significantly moderates the association between satisfaction and action loyalty, and...

  12. ROBUST CONSENSUS AND SOFT CONTROL OF MULTI-AGENT SYSTEMS WITH NOISES

    Institute of Scientific and Technical Information of China (English)

    Lin WANG; Lei GUO

    2008-01-01

    This paper considers the problem of robust consensus for a basic class of multi-agent systems with bounded disturbances and with directed information flow. A necessary and sufficient condition on the robust consensus is first presented, which is then applied to the analysis, control and decision making problems in the noise environments. In particular, the authors show how a soft control technique will synchronize a group of autonomous mobile agents without changing the existing local rule of interactions, and without assuming any kind of connectivity conditions on the system trajectories.

  13. Kalman filter based fault diagnosis of networked control system with white noise

    Institute of Scientific and Technical Information of China (English)

    Yanwei WANG; Ying ZHENG

    2005-01-01

    The networked control system NCS is regarded as a sampled control system with output time-variant delay.White noise is considered in the model construction of NCS.By using the Kalman filter theory to compute the filter parameters,a Kalman filter is constructed for this NCS.By comparing the output of the filter and the practical system,a residual is generated to diagnose the sensor faults and the actuator faults.Finally,an example is given to show the feasibility of the approach.

  14. Active control of radiated sound using nearfield pressure sensing

    Institute of Scientific and Technical Information of China (English)

    CHEN Ke'an; YIN Xuefei

    2004-01-01

    Based on nearfield sound pressure sensing to pick up error information, an approach for constructing active acoustic structure to effectively reduce radiated sound power at low frequency is proposed. The idea is that a nearfield pressure after active control is used as error signals and transformed into an objective function in adaptive active control process.Firstly sound power expression using near-field pressure radiated from a flexible structure is derived, and then three kind of nearfield pressure based active control strategies, I.e. Minimization of radiated sound power, minimization of sound power for dominant radiation modes and minimization of sound power for modified dominant radiation modes are respectively presented and applied to active control of radiated single and broadband noise. Finally computer simulations on sound power reduction under three strategies are conducted and it is shown that the proposed active control strategies are invalid and considerable reduction in radiated sound power can be achieved.

  15. Human ECG signal parameters estimation during controlled physical activity

    Science.gov (United States)

    Maciejewski, Marcin; Surtel, Wojciech; Dzida, Grzegorz

    2015-09-01

    ECG signal parameters are commonly used indicators of human health condition. In most cases the patient should remain stationary during the examination to decrease the influence of muscle artifacts. During physical activity, the noise level increases significantly. The ECG signals were acquired during controlled physical activity on a stationary bicycle and during rest. Afterwards, the signals were processed using a method based on Pan-Tompkins algorithms to estimate their parameters and to test the method.

  16. Design of CMOS Tunable Image-Rejection Low-Noise Amplifier with Active Inductor

    Directory of Open Access Journals (Sweden)

    Ler Chun Lee

    2008-01-01

    Full Text Available A fully integrated CMOS tunable image-rejection low-noise amplifier (IRLNA has been designed using Silterra's industry standard 0.18 μm RF CMOS process. The notch filter is designed using an active inductor. Measurement results show that the notch filter designed using active inductor contributes additional 1.19 dB to the noise figure of the low-noise amplifier (LNA. A better result is possible if the active inductor is optimized. Since active inductors require less die area, the die area occupied by the IRLNA is not significantly different from a conventional LNA, which was designed for comparison. The proposed IRLNA exhibits S21 of 11.8 dB, S11 of −17.8 dB, S22 of −10.7 dB, and input 1 dB compression point of −12 dBm at 3 GHz

  17. Noise Response Data Reveal Novel Controllability Gramian for Nonlinear Network Dynamics.

    Science.gov (United States)

    Kashima, Kenji

    2016-06-06

    Control of nonlinear large-scale dynamical networks, e.g., collective behavior of agents interacting via a scale-free connection topology, is a central problem in many scientific and engineering fields. For the linear version of this problem, the so-called controllability Gramian has played an important role to quantify how effectively the dynamical states are reachable by a suitable driving input. In this paper, we first extend the notion of the controllability Gramian to nonlinear dynamics in terms of the Gibbs distribution. Next, we show that, when the networks are open to environmental noise, the newly defined Gramian is equal to the covariance matrix associated with randomly excited, but uncontrolled, dynamical state trajectories. This fact theoretically justifies a simple Monte Carlo simulation that can extract effectively controllable subdynamics in nonlinear complex networks. In addition, the result provides a novel insight into the relationship between controllability and statistical mechanics.

  18. Global-mode based linear feedback control of a supersonic jet for noise reduction

    Science.gov (United States)

    Natarajan, Mahesh; Freund, Jonathan; Bodony, Daniel

    2016-11-01

    The loudest source of high-speed jet noise appears to be describable by unsteady wavepackets that resemble instabilities. We seek to reduce their acoustic impact with a control strategy that uses global modes to model their dynamics and structural sensitivity of the linearized compressible Navier-Stokes operator to identify an effective linear feedback control. For a case with co-located actuators and sensors adjacent the nozzle, we demonstrate the method on an axisymmetric Mach 1.5 jet. Direct numerical simulations using this control show significant noise reduction. Eigenanalysis of the controlled mean flows reveal fundamental changes in the spectrum at frequencies lower than that used by the control, with the quieter flows having unstable eigenvalues that correspond to eigenfunctions without significant support in the acoustic field. A specific trend is observed in the mean flow quantities as the flow becomes quieter, with changes in the mean flow becoming significant only further downstream of the nozzle exit. The quieter flows also have a stable shock-cell structure that extends further downstream. A phase plot of the POD coefficients for the flows show that the quieter flows are more regular in time. Funded by the Office of Naval Research.

  19. Prediction control of active power filters

    Institute of Scientific and Technical Information of China (English)

    王莉娜; 罗安

    2003-01-01

    A prediction method to obtain harmonic reference for active power filter is presented. It is a new use ofthe adaptive predictive filter based on FIR. The delay inherent in digital controller is successfully compensated by u-sing the proposed method, and the computing load is not very large compared with the conventional method. Moreo-ver, no additional hardware is needed. Its DSP-based realization is also presented, which is characterized by time-va-riant rate sampling, quasi synchronous sampling, and synchronous operation among the line frequency, PWM gener-ating and sampling in A/D unit. Synchronous operation releases the limitation on PWM modulation ratio and guar-antees that the electrical noises resulting from the switching operation of IGBTs do not interfere with the sampledcurrent. The simulation and experimental results verify the satisfactory performance of the proposed method.

  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. Activation barrier scaling and crossover for noise-induced switching in micromechanical parametric oscillators.

    Science.gov (United States)

    Chan, H B; Stambaugh, C

    2007-08-10

    We explore fluctuation-induced switching in parametrically driven micromechanical torsional oscillators. The oscillators possess one, two, or three stable attractors depending on the modulation frequency. Noise induces transitions between the coexisting attractors. Near the bifurcation points, the activation barriers are found to have a power law dependence on frequency detuning with critical exponents that are in agreement with predicted universal scaling relationships. At large detuning, we observe a crossover to a different power law dependence with an exponent that is device specific.

  2. Toward Active Control of Noise from Hot Supersonic Jets

    Science.gov (United States)

    2013-02-15

    applied a double divergence directly to the incompressible Reynolds stress giving Ö U’UI dxgJ = -£ijk(sijUJk + ryWfc). (1) This neglected...SUPERSONIC JETS | QUARTERLY RPT. 6 ^ EXPERIMENTAL FACILITY j^i;r\\’ii Mo/ P I V • Page 6 • Prev • Wart • Last • Full Screen • Close

  3. Active Noise and Vibration Control Literature Survey: Sensors and Actuators

    Science.gov (United States)

    1999-08-01

    concentree sur une vaste gamme de materiaux de capteur et d’actionneur, tels que les materiaux piezoelectriques et electrostrictifs, les materiaux ...sur le probleme du bruit des moteurs diesel, et l’on a pris en consideration les trajets de propagation du bruit, notamment le systeme de suspension ...aux capteurs et aux actionneurs sont donnees. Pour le systeme de suspension du moteur, les arbres d’entrainement et les accouplements mecaniques

  4. Reduction of the radiating sound of a submerged finite cylindrical shell structure by active vibration control.

    Science.gov (United States)

    Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

    2013-02-06

    In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

  5. Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Seung-Bok Choi

    2013-02-01

    Full Text Available In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

  6. Simulation and stability analysis of supersonic impinging jet noise with microjet control

    Science.gov (United States)

    Hildebrand, Nathaniel; Nichols, Joseph W.

    2014-11-01

    A model for an ideally expanded 1.5 Mach turbulent jet impinging on a flat plate using unstructured high-fidelity large eddy simulations (LES) and hydrodynamic stability analysis is presented. Note the LES configuration conforms exactly to experiments performed at the STOVL supersonic jet facility of the Florida Center for Advanced Aero-Propulsion allowing validation against experimental measurements. The LES are repeated for different nozzle-wall separation distances as well as with and without the addition of sixteen microjets positioned uniformly around the nozzle lip. For some nozzle-wall distances, but not all, the microjets result in substantial noise reduction. Observations of substantial noise reduction are associated with a relative absence of large-scale coherent vortices in the jet shear layer. To better understand and predict the effectiveness of microjet noise control, the application of global stability analysis about LES mean fields is used to extract axisymmetric and helical instability modes connected to the complex interplay between the coherent vortices, shocks, and acoustic feedback. We gratefully acknowledge computational resources provided by the Argonne Leadership Computing Facility.

  7. Hanbury-Brown Twiss noise correlation with time controlled quasi-particles in ballistic quantum conductors

    Science.gov (United States)

    Glattli, D. C.; Roulleau, P.

    2016-02-01

    We study the Hanbury Brown and Twiss correlation of electronic quasi-particles injected in a quantum conductor using current noise correlations and we experimentally address the effect of finite temperature. By controlling the relative time of injection of two streams of electrons it is possible to probe the fermionic antibunching, performing the electron analog of the optical Hong Ou Mandel (HOM) experiment. The electrons are injected using voltage pulses with either sine-wave or Lorentzian shape. In the latter case, we propose a set of orthogonal wavefunctions, describing periodic trains of multiply charged electron pulses, which give a simple interpretation to the HOM shot noise. The effect of temperature is then discussed and experimentally investigated. We observe a perfect electron anti-bunching for a large range of temperature, showing that, as recently predicted, thermal mixing of the states does not affect anti-bunching properties, a feature qualitatively different from dephasing. For single charge Lorentzian pulses, we provide experimental evidence of the prediction that the HOM shot noise variation versus the emission time delay is remarkably independent of the temperature.

  8. Modeling of Broadband Liners Applied to the Advanced Noise Control Fan

    Science.gov (United States)

    Nark, Douglas M.; Jones, Michael G.; Sutliff, Daniel L.

    2015-01-01

    The broadband component of fan noise has grown in relevance with an increase in bypass ratio and incorporation of advanced fan designs. Therefore, while the attenuation of fan tones remains a major factor in engine nacelle acoustic liner design, the simultaneous reduction of broadband fan noise levels has received increased interest. As such, a previous investigation focused on improvements to an established broadband acoustic liner optimization process using the Advanced Noise Control Fan (ANCF) rig as a demonstrator. Constant-depth, double-degree of freedom and variable-depth, multi-degree of freedom liner designs were carried through design, fabrication, and testing. This paper addresses a number of areas for further research identified in the initial assessment of the ANCF study. Specifically, incident source specification and uncertainty in some aspects of the predicted liner impedances are addressed. This information is incorporated in updated predictions of the liner performance and comparisons with measurement are greatly improved. Results illustrate the value of the design process in concurrently evaluating the relative costs/benefits of various liner designs. This study also provides further confidence in the integrated use of duct acoustic propagation/radiation and liner modeling tools in the design and evaluation of novel broadband liner concepts for complex engine configurations.

  9. H2 control of discrete-time periodic systems with Markovian jumps and multiplicative noise

    Science.gov (United States)

    Ma, Hongji; Jia, Yingmin

    2013-10-01

    This paper addresses the problem of optimal and robust H2 control for discrete-time periodic systems with Markov jump parameters and multiplicative noise. To analyse the system performance in the presence of exogenous random disturbance, an H2 norm is firstly established on the basis of Gramian matrices. Further, under the condition of exact observability, a necessary and sufficient condition is presented for the solvability of H2 optimal control problem by means of a generalised Riccati equation. When the transition probabilities of jump parameter are incompletely measurable, an H2-guaranteed cost norm is exploited and the robust H2 controller is designed through a linear matrix inequality (LMI) optimisation approach. An example of a networked control system is supplied to illustrate the proposed results.

  10. Likelihood-Based Hypothesis Tests for Brain Activation Detection From MRI Data Disturbed by Colored Noise: A Simulation Study

    NARCIS (Netherlands)

    Den Dekker, A.J.; Poot, D.H.J.; Bos, R.; Sijbers, J.

    2009-01-01

    Functional magnetic resonance imaging (fMRI) data that are corrupted by temporally colored noise are generally preprocessed (i.e., prewhitened or precolored) prior to functional activation detection. In this paper, we propose likelihood-based hypothesis tests that account for colored noise directly

  11. 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.

  12. Experimentation Toward the Analysis of Gear Noise Sources Controlled by Sliding Friction and Surface Roughness

    Science.gov (United States)

    Asnani, Vivake M.

    2004-01-01

    In helicopters and other rotorcraft, the gearbox is a major source of noise and vibration (N&V). The two N&V excitation mechanisms are the relative displacements between mating gears (transmission errors) and the friction associated with sliding between gear teeth. Historically, transmission errors have been minimized via improved manufacturing accuracies and tooth modifications. Yet, at high torque loads, noise levels are still relatively high though transmission errors might be somewhat minimal. This suggests that sliding friction is indeed a dominant noise source for high power density rotorcraft gearboxes. In reality, friction source mechanism is associated with surface roughness, lubrication regime properties, time-varying friction forces/torques and gear-mesh interface dynamics. Currently, the nature of these mechanisms is not well understood, while there is a definite need for analytical tools that incorporate sliding resistance and surface roughness, and predict their effects on the vibro- acoustic behavior of gears. Toward this end, an experiment was conducted to collect sound and vibration data on the NASA Glenn Gear-Noise Rig. Three iterations of the experiment were accomplished: Iteration 1 tested a baseline set of gears to establish a benchmark. Iteration 2 used a gear-set with low surface asperities to reduce the sliding friction excitation. Iteration 3 incorporated low viscosity oil with the baseline set of gears to examine the effect of lubrication. The results from this experiment will contribute to a two year project in collaboration with the Ohio State University to develop the necessary mathematical and computer models for analyzing geared systems and explain key physical phenomena seen in experiments. Given the importance of sliding friction in the gear dynamic and vibro-acoustic behavior of rotorcraft gearboxes, there is considerable potential for research & developmental activities. Better models and understanding will lead to quiet and

  13. Minimum-noise production of translation factor eIF4G maps to a mechanistically determined optimal rate control window for protein synthesis

    Science.gov (United States)

    Meng, Xiang; Firczuk, Helena; Pietroni, Paola; Westbrook, Richard; Dacheux, Estelle; Mendes, Pedro; McCarthy, John E.G.

    2017-01-01

    Gene expression noise influences organism evolution and fitness. The mechanisms determining the relationship between stochasticity and the functional role of translation machinery components are critical to viability. eIF4G is an essential translation factor that exerts strong control over protein synthesis. We observe an asymmetric, approximately bell-shaped, relationship between the average intracellular abundance of eIF4G and rates of cell population growth and global mRNA translation, with peak rates occurring at normal physiological abundance. This relationship fits a computational model in which eIF4G is at the core of a multi-component–complex assembly pathway. This model also correctly predicts a plateau-like response of translation to super-physiological increases in abundance of the other cap-complex factors, eIF4E and eIF4A. Engineered changes in eIF4G abundance amplify noise, demonstrating that minimum stochasticity coincides with physiological abundance of this factor. Noise is not increased when eIF4E is overproduced. Plasmid-mediated synthesis of eIF4G imposes increased global gene expression stochasticity and reduced viability because the intrinsic noise for this factor influences total cellular gene noise. The naturally evolved eIF4G gene expression noise minimum maps within the optimal activity zone dictated by eIF4G's mechanistic role. Rate control and noise are therefore interdependent and have co-evolved to share an optimal physiological abundance point. PMID:27928055

  14. Active-control headset protector using piezoceramic material actuator

    Science.gov (United States)

    Brissaud, Michel; Gonnard, Paul; Bera, Jean-Christophe; Sunyach, Michel

    1996-04-01

    This paper describes the achievement of active control headset protector using piezoceramic actuators leading to a noise attenuation of about 20 dB within a 1 kHz frequency span located at around 1 to 2 kHz. To this end, several types of piezoceramic transducers or actuators have been designed and tested. They are based on flexural modes of bimorphs constituted by a thin piezoelectric ceramic disk cemented on a metallic plate. The main problems encountered are the spurious frequency regenerations which mask the noise reduction in the expected frequency range. Thus only a few of them meet the above specifications and can be used for reducing the noise inside the headset protector.

  15. Proximal versus distal control of two-joint planar reaching movements in the presence of neuromuscular noise.

    Science.gov (United States)

    Nguyen, Hung P; Dingwell, Jonathan B

    2012-06-01

    Determining how the human nervous system contends with neuro-motor noise is vital to understanding how humans achieve accurate goal-directed movements. Experimentally, people learning skilled tasks tend to reduce variability in distal joint movements more than in proximal joint movements. This suggests that they might be imposing greater control over distal joints than proximal joints. However, the reasons for this remain unclear, largely because it is not experimentally possible to directly manipulate either the noise or the control at each joint independently. Therefore, this study used a 2 degree-of-freedom torque driven arm model to determine how different combinations of noise and/or control independently applied at each joint affected the reaching accuracy and the total work required to make the movement. Signal-dependent noise was simultaneously and independently added to the shoulder and elbow torques to induce endpoint errors during planar reaching. Feedback control was then applied, independently and jointly, at each joint to reduce endpoint error due to the added neuromuscular noise. Movement direction and the inertia distribution along the arm were varied to quantify how these biomechanical variations affected the system performance. Endpoint error and total net work were computed as dependent measures. When each joint was independently subjected to noise in the absence of control, endpoint errors were more sensitive to distal (elbow) noise than to proximal (shoulder) noise for nearly all combinations of reaching direction and inertia ratio. The effects of distal noise on endpoint errors were more pronounced when inertia was distributed more toward the forearm. In contrast, the total net work decreased as mass was shifted to the upper arm for reaching movements in all directions. When noise was present at both joints and joint control was implemented, controlling the distal joint alone reduced endpoint errors more than controlling the proximal joint

  16. A secondary source configuration for control of a ventilation fan noise in ducts

    OpenAIRE

    Čudina, Mirko; Prezelj, Jurij

    2015-01-01

    The main noise source in heating, ventilation, and air conditioning systems is usually a ventilating fan. Noise, generated by the ventilating fan is transmitted through the duct into the living and working environment. A typical fan noise spectrum consists of a broadband noise, which is superimposed with pure tones. Different methods are available to reduce a transmission of such noise from the ventilating fan into the living and working environment. In this article it is demonstrated how a f...

  17. Hearing an illusory vowel in noise: suppression of auditory cortical activity.

    Science.gov (United States)

    Riecke, Lars; Vanbussel, Mieke; Hausfeld, Lars; Başkent, Deniz; Formisano, Elia; Esposito, Fabrizio

    2012-06-06

    Human hearing is constructive. For example, when a voice is partially replaced by an extraneous sound (e.g., on the telephone due to a transmission problem), the auditory system may restore the missing portion so that the voice can be perceived as continuous (Miller and Licklider, 1950; for review, see Bregman, 1990; Warren, 1999). The neural mechanisms underlying this continuity illusion have been studied mostly with schematic stimuli (e.g., simple tones) and are still a matter of debate (for review, see Petkov and Sutter, 2011). The goal of the present study was to elucidate how these mechanisms operate under more natural conditions. Using psychophysics and electroencephalography (EEG), we assessed simultaneously the perceived continuity of a human vowel sound through interrupting noise and the concurrent neural activity. We found that vowel continuity illusions were accompanied by a suppression of the 4 Hz EEG power in auditory cortex (AC) that was evoked by the vowel interruption. This suppression was stronger than the suppression accompanying continuity illusions of a simple tone. Finally, continuity perception and 4 Hz power depended on the intactness of the sound that preceded the vowel (i.e., the auditory context). These findings show that a natural sound may be restored during noise due to the suppression of 4 Hz AC activity evoked early during the noise. This mechanism may attenuate sudden pitch changes, adapt the resistance of the auditory system to extraneous sounds across auditory scenes, and provide a useful model for assisted hearing devices.

  18. Noise Control Using Coconut Coir Fiber Sound Absorber with Porous Layer Backing and Perforated Panel

    Directory of Open Access Journals (Sweden)

    Rozli Zulkifli

    2010-01-01

    Full Text Available Problem statement: Noise control was one of the major requirements to improve the living environment. One of the methods to do that is provided by sound absorber. Commonly, multi-layer sound absorbers are applied to absorb broadband noise that was composed of perforated plates, air space and porous material. However, multi-layers sound absorbers effectiveness depends on their construction. This study was conducted to investigate the potential of using coconut coir fiber as sound absorber. The effects of porous layer backing and perforated plate on sound absorption coefficient of sound absorber using coconut coir fiber were studied. Approach: Car boot liners made from woven cotton cloth were used as type of porous layer in the study. This material has been used widely in automotive industry. Perforated plate used was machined with perforation ratio of 0.20, thickness of 1 mm and holed diameter of 2 mm. The samples were tested at the acoustic lab of the Faculty of Engineering and Built Environment, University Kebangsaan Malaysia, according to ASTM E 1050-98 international standards for noise absorption coefficient. Results: The experiment data indicates that porous layer backing can improve noise absorption coefficient at low and high frequencies with significant increasing. 20 mm thick layer coconut coir fiber with porous layer backing exhibit peak value at frequencies between 2750-2825 Hz with maximum value of 0.97. The experimental results also found that the coconut coir fiber with perforated plate gives higher value for lower frequencies range from 600-2400 Hz. The optimum value for coconut coir fiber with perforated panel is around 0.94-0.95 for the frequency range 2600-2700 Hz. Conclusion: Noise absorption coefficient of coconut coir fiber was increased at all frequency when they were backing with Woven Cotton Cloth (WCC. At low frequency, the NAC have significant increasing. This is because WCC have higher flow resistivity than coconut coir

  19. Demonstration of Active Combustion Control

    Science.gov (United States)

    Lovett, Jeffrey A.; Teerlinck, Karen A.; Cohen, Jeffrey M.

    2008-01-01

    The primary objective of this effort was to demonstrate active control of combustion instabilities in a direct-injection gas turbine combustor that accurately simulates engine operating conditions and reproduces an engine-type instability. This report documents the second phase of a two-phase effort. The first phase involved the analysis of an instability observed in a developmental aeroengine and the design of a single-nozzle test rig to replicate that phenomenon. This was successfully completed in 2001 and is documented in the Phase I report. This second phase was directed toward demonstration of active control strategies to mitigate this instability and thereby demonstrate the viability of active control for aircraft engine combustors. This involved development of high-speed actuator technology, testing and analysis of how the actuation system was integrated with the combustion system, control algorithm development, and demonstration testing in the single-nozzle test rig. A 30 percent reduction in the amplitude of the high-frequency (570 Hz) instability was achieved using actuation systems and control algorithms developed within this effort. Even larger reductions were shown with a low-frequency (270 Hz) instability. This represents a unique achievement in the development and practical demonstration of active combustion control systems for gas turbine applications.

  20. Control of sound radiation with active/adaptive structures

    Science.gov (United States)

    Fuller, C. R.; Rogers, C. A.; Robertshaw, H. H.

    1992-01-01

    Recent research is discussed in the area of active structural acoustic control with active/adaptive structures. Progress in the areas of structural acoustics, actuators, sensors, and control approaches is presented. Considerable effort has been given to the interaction of these areas with each other due to the coupled nature of the problem. A discussion is presented on actuators bonded to or embedded in the structure itself. The actuators discussed are piezoceramic actuators and shape memory alloy actuators. The sensors discussed are optical fiber sensors, Nitinol fiber sensors, piezoceramics, and polyvinylidene fluoride sensors. The active control techniques considered are state feedback control techniques and least mean square adaptive algorithms. Results presented show that significant progress has been made towards controlling structurally radiated noise by active/adaptive means applied directly to the structure.