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 in Propeller Aircraft

    OpenAIRE

    Johansson, Sven; Claesson, Ingvar

    2001-01-01

    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 addresses same design aspects for multiple-reference active noise control systems based on th...

  3. Active Noise Control in Forest Machines

    OpenAIRE

    Forsgren, Fredrik

    2011-01-01

    Achieving a low noise level is of great interest to the forest machine industry. Traditionally this is obtained by using passive noise reduction, i.e. by using materials for sound isolation and sound absorption. Especially designs to attenuate low frequency noise tend to be bulky and impractical from an installation point of view. An alternative solution to the problem is to use active noise control (ANC). The basic principle of ANC is to generate an anti-noise signal designed to destructivel...

  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. 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.

  7. 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

  8. 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.

  9. Active noise control for high frequencies

    OpenAIRE

    Kaymak, E; Atherton, MA; Rotter, KRG; Millar, B.

    2006-01-01

    There are many applications that can benefit from Active Noise Control (ANC) such as in aircraft cabins and air conditioning ducts, i.e. in situations where technology interferes with human hearing in a harmful way or disrupts communication. Headsets with analogue ANC circuits have been used in the armed forces for attenuating frequencies below 1 kHz, which when combined with passive filtering offers protection across the whole frequency range of human hearing. A dental surgery is also a nois...

  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 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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...

  19. Active Control of Aerodynamic Noise Sources

    Science.gov (United States)

    Reynolds, Gregory A.

    2001-01-01

    Aerodynamic noise sources become important when propulsion noise is relatively low, as during aircraft landing. Under these conditions, aerodynamic noise from high-lift systems can be significant. The research program and accomplishments described here are directed toward reduction of this aerodynamic noise. Progress toward this objective include correction of flow quality in the Low Turbulence Water Channel flow facility, development of a test model and traversing mechanism, and improvement of the data acquisition and flow visualization capabilities in the Aero. & Fluid Dynamics Laboratory. These developments are described in this report.

  20. Active Noise Control Experiments using Sound Energy Flu

    Science.gov (United States)

    Krause, Uli

    2015-03-01

    This paper reports on the latest results concerning the active noise control approach using net flow of acoustic energy. The test set-up consists of two loudspeakers simulating the engine noise and two smaller loudspeakers which belong to the active noise system. The system is completed by two acceleration sensors and one microphone per loudspeaker. The microphones are located in the near sound field of the loudspeakers. The control algorithm including the update equation of the feed-forward controller is introduced. Numerical simulations are performed with a comparison to a state of the art method minimising the radiated sound power. The proposed approach is experimentally validated.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Active structural acoustic control of aircraft interior flow noise via the use of active trim panels

    OpenAIRE

    Mahnken, Brian W.

    1996-01-01

    Modem jet aircraft interior noise can be categorized into two main types: tonal noise caused by engine imbalance or blade passage, and mid frequency broadband noise resulting from turbulent flow. This project addresses aircraft interior flow noise caused by a flow separation over the crown of the aircraft. The noise control approach is to mount piezoelectric actuators to the aircraft interior cockpit crown trim panel and use them to actively control aircraft interior noise with...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Active Flow Effectors for Noise and Separation Control

    Science.gov (United States)

    Turner, Travis L.

    2011-01-01

    New flow effector technology for separation control and enhanced mixing is based upon shape memory alloy hybrid composite (SMAHC) technology. The technology allows for variable shape control of aircraft structures through actively deformable surfaces. The flow effectors are made by embedding shape memory alloy actuator material in a composite structure. When thermally actuated, the flow effector def1ects into or out of the flow in a prescribed manner to enhance mixing or induce separation for a variety of applications, including aeroacoustic noise reduction, drag reduction, and f1ight control. The active flow effectors were developed for noise reduction as an alternative to fixed-configuration effectors, such as static chevrons, that cannot be optimized for airframe installation effects or variable operating conditions and cannot be retracted for off-design or fail-safe conditions. Benefits include: Increased vehicle control, overall efficiency, and reduced noise throughout all f1ight regimes, Reduced flow noise, Reduced drag, Simplicity of design and fabrication, Simplicity of control through direct current stimulation, autonomous re sponse to environmental heating, fast re sponse, and a high degree of geometric stability. The concept involves embedding prestrained SMA actuators on one side of the chevron neutral axis in order to generate a thermal moment and def1ect the structure out of plane when heated. The force developed in the host structure during def1ection and the aerodynamic load is used for returning the structure to the retracted position. The chevron design is highly scalable and versatile, and easily affords active and/or autonomous (environmental) control. The technology offers wide-ranging market applications, including aerospace, automotive, and any application that requires flow separation or noise control.

  15. The passive and active noise control strategy in the aircraft interior noise

    OpenAIRE

    Paonessa, A.

    1994-01-01

    The stringent comfort requirements that the airliners are providing to the aircraft manufacturers, also for the small regional commuter are increasing the attention of the aircraft designer to the aircraft interior noise performance. The research on the design methodologies is very much improved in the last years providing new materials and new system like the active noise control usefull to get a more comfortable interior and achieve a large competition on the market. In this paper a general...

  16. 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.

  17. 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.)

  18. 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.

  19. 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

  20. Active noise control to reduce the blade tone noise of centrifugal fans

    Science.gov (United States)

    Koopmann, G. H.; Neise, W.; Chen, W.

    1988-07-01

    An active noise control method for suppressing the blade tones of centrifugal fans is presented which uses two secondary sound sources mounted into the cutoff region of the fan casing. Experiments were conducted for centrifugal fans with impeller diameters between 280 and 710 mm using two different designs for the secondary sources. The results indicate that the sound field inside the casing is dominated by the rotor locked pressure field, and that the blade tone noise measured in the far-field is generated by the unsteady pressures at the cutoff, which in turn are produced by the flow leaving the impeller.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.)

  7. Active control of fan noise from a turbofan engine

    Science.gov (United States)

    Thomas, Russell H.; Burdisso, Ricardo A.; Fuller, Christopher R.; O'Brien, Walter F.

    1993-01-01

    A three channel active control system is applied to an operational turbofan engine in order to reduce tonal noise produced by both the fan and high pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provides blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. In order to minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three channel controller by up to 16 dB over a 60 deg angle about the engine axis. A single channel controller could produce reduction over a 30 deg angle. The experimental results show the control to be robust. Simultaneous control of two tones is done with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 dBA and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high pressure compressor fundamental tones.

  8. 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.

  9. 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.

  10. Active Control of Fan Noise-Feasibility Study. Volume 1; Flyover System Noise Studies

    Science.gov (United States)

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

    1994-01-01

    A 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. Thus, without considering the engineering details of the ANC system design, tone levels are 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 from 1.3 to 1.75. The major conclusions that can be drawn are that, for a fan pressure ratio of 1.75, ANC of tones gives about the same suppression as acoustic treatment without ANC, and for a fan pressure ratio of 1.45, ANC appears to offer less effectiveness than passive treatment. Additionally, ANC appears to be more effective at sideline and cutback conditions than at approach. Overall EPNL suppressions due to tone removal range from about 1 to 3 dB at takeoff engine speeds and from 1 to 5 db at approach speeds. Studies of economic impact of the installation of an ANC system for the four engine cases indicate increases of DOC ranging from 1 to 2 percent, favoring the lower fan pressure ratio engines. Further study is needed to confirm the results by examining additional engine data, particularly at low fan pressure ratios, and studying the details of the current results to obtain a more complete understanding. Further studies should also include determining the effects of combining passive and active treatment.

  11. 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.

  12. A study on transient enhancement for fault diagnosis based on an active noise control system

    OpenAIRE

    Tian, X.; Gu, Fengshou; Zhen, Dong; Tran, Tung; Ball, Andrew

    2012-01-01

    Active noise control (ANC) is a more effective technique used for acoustic noise cancelation in comparison with passive approaches which are difficult and expensive to implement, especially for cancelling the noise in the low frequency range. In the ANC system, an anti-noise signal is introduced to suppress the primary noise to produce a residual which is used for updating the adaptive filter coefficients. In this paper, a method of transient content enhancement for fault detection and diagno...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

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

    OpenAIRE

    N.V.K.Mahalakshmi; Sindhu, D; B. Ranjith Kumar; N.Santhisri; G. Sowjanya Rao

    2014-01-01

    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 p...

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  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 are init...

  10. 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.

  11. 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.

  12. 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.

  13. Active noise cancellation algorithms for impulsive noise

    OpenAIRE

    Li, Peng; Yu, Xun

    2012-01-01

    Impulsive noise is an important challenge for the practical implementation of active noise control (ANC) systems. The advantages and disadvantages of popular filtered-X least mean square (FXLMS) ANC algorithm and nonlinear filtered-X least mean M-estimate (FXLMM) algorithm are discussed in this paper. A new modified FXLMM algorithm is also proposed to achieve better performance in controlling impulsive noise. Computer simulations and experiments are carried out for all three algorithms and th...

  14. 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.

  15. 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.

  16. The effect of structural-acoustic coupling on the active control of noise in vehicles

    OpenAIRE

    Cheer, Jordan; Elliott, Stephen J.

    2011-01-01

    Active noise control systems offer a potential method of reducing the weight of passive acoustic treatment and, therefore, increasing vehicles’ fuel ef?ciency. These can be particularly cost-ef?cient if integrated with the entertainment system. A combined system is presented employing feedforward control of engine noise and feedback control of road noise, using a‘modal’ error signal. Due to the dependence of the feedback system on the modal response of the vehicle cabin, and the in?uence of s...

  17. 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.

  18. 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. .

  19. 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.)

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.)

  5. 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.

  6. 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

  7. 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).

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Source localization for active control of turbofan rotor-stator broadband noise

    Science.gov (United States)

    Walker, Bruce E.

    2005-09-01

    In order to identify a reference signal source for an active noise cancellation system, cross-correlation techniques were used to localize broadband noise source regions on exit guide vanes of the NASA Glenn Research Center Advance Noise Control Fan (ANCF). Arrays of surface pressure sensors were imbedded in one guide vane and in the wall of the fan. Synchronous sampling was used with a multichannel data acquisition system to allow removal of periodic components from the signals. The signals were then cross-correlated to assess radiation directivity and the relationship between vane surface pressure and in-duct acoustic noise. The results of these measurements indicated that broadband unsteady pressures near the leading edge tip of the guide vane were well enough correlated with acoustic radiation that 2-3 dB active noise cancellation could be achieved using a simple gain-delay control algorithm and actuator array. After successful simulation in a wind tunnel environment the concept was incorporated on 15 guide vanes and tested in ANCF. Cross-correlation measurements were further used to evaluate system performance and to identify competing noises from rotating and stationary sources within the fan.

  14. 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

  15. 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.

  16. 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.

  17. Active Control of Inlet Noise on the JT15D Turbofan Engine

    Science.gov (United States)

    Smith, Jerome P.; Hutcheson, Florence V.; Burdisso, Ricardo A.; Fuller, Chris R.

    1999-01-01

    This report presents the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the year from November 1997 to December 1998 on the Active Noise Control of Turbofan Engines research project funded by NASA Langley Research Center. The concept of implementing active noise control techniques with fuselage-mounted error sensors is investigated both analytically and experimentally. The analytical part of the project involves the continued development of an advanced modeling technique to provide prediction and design guidelines for application of active noise control techniques to large, realistic high bypass engines of the type on which active control methods are expected to be applied. Results from the advanced analytical model are presented that show the effectiveness of the control strategies, and the analytical results presented for fuselage error sensors show good agreement with the experimentally observed results and provide additional insight into the control phenomena. Additional analytical results are presented for active noise control used in conjunction with a wavenumber sensing technique. The experimental work is carried out on a running JT15D turbofan jet engine in a test stand at Virginia Tech. The control strategy used in these tests was the feedforward Filtered-X LMS algorithm. The control inputs were supplied by single and multiple circumferential arrays of acoustic sources equipped with neodymium iron cobalt magnets mounted upstream of the fan. The reference signal was obtained from an inlet mounted eddy current probe. The error signals were obtained from a number of pressure transducers flush-mounted in a simulated fuselage section mounted in the engine test cell. The active control methods are investigated when implemented with the control sources embedded within the acoustically absorptive material on a passively-lined inlet. The experimental results show that the combination of active control techniques with fuselage

  18. 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.

  19. 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. PMID:21568404

  20. A boundary element approach to optimization of active noise control sources on three-dimensional structures

    Science.gov (United States)

    Cunefare, K. A.; Koopmann, G. H.

    1991-01-01

    This paper presents the theoretical development of an approach to active noise control (ANC) applicable to three-dimensional radiators. The active noise control technique, termed ANC Optimization Analysis, is based on minimizing the total radiated power by adding secondary acoustic sources on the primary noise source. ANC Optimization Analysis determines the optimum magnitude and phase at which to drive the secondary control sources in order to achieve the best possible reduction in the total radiated power from the noise source/control source combination. For example, ANC Optimization Analysis predicts a 20 dB reduction in the total power radiated from a sphere of radius at a dimensionless wavenumber ka of 0.125, for a single control source representing 2.5 percent of the total area of the sphere. ANC Optimization Analysis is based on a boundary element formulation of the Helmholtz Integral Equation, and thus, the optimization analysis applies to a single frequency, while multiple frequencies can be treated through repeated analyses.

  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. 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.

  5. An active structural acoustic control approach for the reduction of the structure-borne road noise

    Science.gov (United States)

    Douville, Hugo; Berry, Alain; Masson, Patrice

    2002-11-01

    The reduction of the structure-borne road noise generated inside the cabin of an automobile is investigated using an Active Structural Acoustic Control (ASAC) approach. First, a laboratory test bench consisting of a wheel/suspension/lower suspension A-arm assembly has been developed in order to identify the vibroacoustic transfer paths (up to 250 Hz) for realistic road noise excitation of the wheel. Frequency Response Function (FRF) measurements between the excitation/control actuators and each suspension/chassis linkage are used to characterize the different transfer paths that transmit energy through the chassis of the car. Second, a FE/BE model (Finite/Boundary Elements) was developed to simulate the acoustic field of an automobile cab interior. This model is used to predict the acoustic field inside the cabin as a response to the measured forces applied on the suspension/chassis linkages. Finally, an experimental implementation of ASAC is presented. The control approach relies on the use of inertial actuators to modify the vibration behavior of the suspension and the automotive chassis such that its noise radiation efficiency is decreased. The implemented algorithm consists of a MIMO (Multiple-Input-Multiple-Output) feedforward configuration with a filtered-X LMS algorithm using an advanced reference signal (width FIR filters) using the Simulink/Dspace environment for control prototyping.

  6. 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.

  7. Active Structural Acoustic Control of Interior Noise on a Raytheon 1900D

    Science.gov (United States)

    Palumbo, Dan; Cabell, Ran; Sullivan, Brenda; Cline, John

    2000-01-01

    An active structural acoustic control system has been demonstrated on a Raytheon Aircraft Company 1900D turboprop airliner. Both single frequency and multi-frequency control of the blade passage frequency and its harmonics was accomplished. The control algorithm was a variant of the popular filtered-x LMS implemented in the principal component domain. The control system consisted of 21 inertial actuators and 32 microphones. The actuators were mounted to the aircraft's ring frames. The microphones were distributed uniformly throughout the interior at head height, both seated and standing. Actuator locations were selected using a combinatorial search optimization algorithm. The control system achieved a 14 dB noise reduction of the blade passage frequency during single frequency tests. Multi-frequency control of the first 1st, 2nd and 3rd harmonics resulted in 10.2 dB, 3.3 dB and 1.6 dB noise reductions respectively. These results fall short of the predictions which were produced by the optimization algorithm (13.5 dB, 8.6 dB and 6.3 dB). The optimization was based on actuator transfer functions taken on the ground and it is postulated that cabin pressurization at flight altitude was a factor in this discrepancy.

  8. 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

  9. 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.

  10. 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.

  11. Structural Acoustic Characteristics of Aircraft and Active Control of Interior Noise

    Science.gov (United States)

    Fuller, C. R.

    1998-01-01

    The reduction of aircraft cabin sound levels to acceptable values still remains a topic of much research. The use of conventional passive approaches has been extensively studied and implemented. However performance limits of these techniques have been reached. In this project, new techniques for understanding the structural acoustic behavior of aircraft fuselages and the use of this knowledge in developing advanced new control approaches are investigated. A central feature of the project is the Aircraft Fuselage Test Facility at Va Tech which is based around a full scale Cessna Citation III fuselage. The work is divided into two main parts; the first part investigates the use of an inverse technique for identifying dominant fuselage vibrations. The second part studies the development and implementation of active and active-passive techniques for controlling aircraft interior noise.

  12. 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.

  13. 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.

  14. 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....... Three sets of experimental results are presented and supported by results from computer simulations. Thus, a number of observations and guidelines for the design of such a control system that so far have been drawn only from theory and simulation studies are discussed based on experimental results from...... laboratory. The study of the full control system, which comprises thirty secondary sources and thirty-two error sensors, has revealed a number of new results, in particular with respect to the positioning of the sources and sensors along the length of the duct. Eventually, a reduction of the radiated power...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Chain reconfiguration in active noise

    International Nuclear Information System (INIS)

    In a typical single molecule experiment, the dynamics of an unfolded protein is studied by determining the reconfiguration time using long-range Förster resonance energy transfer, where the reconfiguration time is the characteristic decay time of the position correlation between two residues of the protein. In this paper we theoretically calculate the reconfiguration time for a single flexible polymer in the presence of active noise. The study suggests that though the mean square displacement grows faster, the chain reconfiguration is always slower in the presence of long-lived active noise with exponential temporal correlation. Similar behavior is observed for a worm-like semi-flexible chain and a Zimm chain. However it is primarily the characteristic correlation time of the active noise and not the strength that controls the increase in the reconfiguration time. In brief, such active noise makes the polymer move faster but the correlation loss between the monomers becomes slow. (paper)

  2. 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.)

  3. Active road noise reduction

    OpenAIRE

    Vraničar, Primož

    2012-01-01

    Theoretical principle of noise cancellation can be realized in the ideal studio conditions, but when the experiment is put into actual space and realized, we can see that the sound only partly cancels itself, on some frequencies more and on some less. However, in construction engineering we are not only dealing with certain frequencies but with frequency spectrums, if not with the whole frequency field. It is relatively hard to control the noise in traffic. We are dealing with a larger freque...

  4. Noise control mechanisms of inside aircraft

    Science.gov (United States)

    Zverev, A. Ya.

    2016-07-01

    World trends in the development of methods and approaches to noise reduction in aircraft cabins are reviewed. The paper discusses the mechanisms of passive and active noise and vibration control, application of "smart" and innovative materials, new approaches to creating all fuselage-design elements, and other promising directions of noise control inside aircraft.

  5. 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.

  6. Adaptive RSOV filter using the FELMS algorithm for nonlinear active noise control systems

    Science.gov (United States)

    Zhao, Haiquan; Zeng, Xiangping; He, Zhengyou; Li, Tianrui

    2013-01-01

    This paper presents a recursive second-order Volterra (RSOV) filter to solve the problems of signal saturation and other nonlinear distortions that occur in nonlinear active noise control systems (NANC) used for actual applications. Since this nonlinear filter based on an infinite impulse response (IIR) filter structure can model higher than second-order and third-order nonlinearities for systems where the nonlinearities are harmonically related, the RSOV filter is more effective in NANC systems with either a linear secondary path (LSP) or a nonlinear secondary path (NSP). Simulation results clearly show that the RSOV adaptive filter using the multichannel structure filtered-error least mean square (FELMS) algorithm can further greatly reduce the computational burdens and is more suitable to eliminate nonlinear distortions in NANC systems than a SOV filter, a bilinear filter and a third-order Volterra (TOV) filter.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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。

  12. 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.

  13. 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.)

  14. 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。

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Development of Adjustable Absorption Acoustic Liner for Active Fan Noise Control

    OpenAIRE

    小林, 紘; Kobayashi, Hiroshi

    2003-01-01

    Due to strong demands from communities adjacent to airports for the suppression aircraft noise, a new aircraft noise certification standard as set out in ICAO Chapter 4 was formulated and will come into effect in 2006 for new subsonic aircrafts. Currently, not only aircraft noise affecting communities surrounding airports but also aircraft noise at night, during climb and while cruising have become serious issues. In order to solve these issues, at NAL, new techniques and systems have been de...

  5. Active Control of Fan Noise-Feasibility Study. Volume 2: Canceling Noise Source-Design of an Acoustic Plate Radiator Using Piezoceramic Actuators

    Science.gov (United States)

    Pla, F. G.; Rajiyah, H.

    1995-01-01

    The feasibility of using acoustic plate radiators powered by piezoceramic thin sheets as canceling sources for active control of aircraft engine fan noise is demonstrated. Analytical and numerical models of actuated beams and plates are developed and validated. An optimization study is performed to identify the optimum combination of design parameters that maximizes the plate volume velocity for a given resonance frequency. Fifteen plates with various plate and actuator sizes, thicknesses, and bonding layers were fabricated and tested using results from the optimization study. A maximum equivalent piston displacement of 0.39 mm was achieved with the optimized plate samples tested with only one actuator powered, corresponding to a plate deflection at the center of over 1 millimeter. This is very close to the deflection required for a full size engine application and represents a 160-fold improvement over previous work. Experimental results further show that performance is limited by the critical stress of the piezoceramic actuator and bonding layer rather than by the maximum moment available from the actuator. Design enhancements are described in detail that will lead to a flight-worthy acoustic plate radiator by minimizing actuator tensile stresses and reducing nonlinear effects. Finally, several adaptive tuning methods designed to increase the bandwidth of acoustic plate radiators are analyzed including passive, active, and semi-active approaches. The back chamber pressurization and volume variation methods are investigated experimentally and shown to be simple and effective ways to obtain substantial control over the resonance frequency of a plate radiator. This study shows that piezoceramic-based plate radiators can be a viable acoustic source for active control of aircraft engine fan noise.

  6. Development and experimental verification of a robust active noise control system for a diesel engine in submarines

    Science.gov (United States)

    Sachau, D.; Jukkert, S.; Hövelmann, N.

    2016-08-01

    This paper presents the development and experimental validation of an ANC (active noise control)-system designed for a particular application in the exhaust line of a submarine. Thereby, tonal components of the exhaust noise in the frequency band from 75 Hz to 120 Hz are reduced by more than 30 dB. The ANC-system is based on the feedforward leaky FxLMS-algorithm. The observability of the sound pressure in standing wave field is ensured by using two error microphones. The noninvasive online plant identification method is used to increase the robustness of the controller. Online plant identification is extended by a time-varying convergence gain to improve the performance in the presence of slight error in the frequency of the reference signal.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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 .

  13. 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.

  14. 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.

  15. Increased noise level of purkinje cell activities minimizes impact of their modulation during sensorimotor control.

    NARCIS (Netherlands)

    Hoebeek, F.E.; Stahl, J.S.; Alphen, A.M. van; Schonewille, M.; Luo, C.; Rutteman, M.; Maagdenberg, A.M.J.M. van den; Molenaar, P.C.; Goossens, H.H.L.M.; Frens, M.A.; Zeeuw, C.I. de

    2005-01-01

    While firing rate is well established as a relevant parameter for encoding information exchanged between neurons, the significance of other parameters is more conjectural. Here, we show that regularity of neuronal spike activities affects sensorimotor processing in tottering mutants, which suffer fr

  16. 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.…

  17. 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

    Particulate air pollution increases risk of cancer and cardiopulmonary disease, partly through oxidative stress. Traffic-related noise increases risk of cardiovascular disease and may cause oxidative stress. In this controlled random sequence study, 18 healthy subjects were exposed for 3h to diesel...... exhaust (DE) at 276μg/m(3) from a passenger car or filtered air, with co-exposure to traffic noise at 48 or 75dB(A). Gene expression markers of inflammation, (interleukin-8 and tumor necrosis factor), oxidative stress (heme oxygenase (decycling-1)) and DNA repair (8-oxoguanine DNA glycosylase (OGG1)) were...... molecules in leukocyte subtypes. CONCLUSION: 3-h exposure to DE caused no genotoxicity, oxidative stress or inflammation in PBMCs, whereas exposure to noise might cause oxidatively damaged DNA....

  18. 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.

  19. Noise and Vibration Control of Combustion Engine Vehicles

    OpenAIRE

    Winberg, Mathias

    2005-01-01

    Noise and vibrations have over the last two decades been regarded as significant environmental health problems. Regulations regarding acoustic as well as vibration levels have therefore become more stringent. This thesis embraces two different techniques to reduce unwanted noise and vibrations, spectral subtraction and active noise and vibration control. The applications treated for noise and vibration problems are mainly means of transportation driven by combustion engines as for example, he...

  20. 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

  1. Condominium Design: Good and Bad Noise Control.

    Science.gov (United States)

    Hargens, C. W.; Schutz, Victor K.

    This paper discusses pitfalls in condominium design and the incorpoation of related noise control problems into classroom situations. Two case studies are provided, and a list of architectural noise problems found in many condominiums is included. (CP)

  2. Feedback Control for Noise Reduction Program

    Science.gov (United States)

    Tucker, Jerry H.

    2002-12-01

    As part of Langley Research Center's continuing noise reduction program, an active noise control system (ANC) is being developed to suppress noise inside an aircraft cabin. This interior noise reduction system consists of the following major components: 1. Several accelerometers. 2. An input amplifier. 3. A digital signal processor (DSP) system that includes an analog to digital converter (ADC) and a digital to analog converter (DAC). 4. A high voltage power amplifier. 5. PZT actuators. 6. Power supply and distribution. The accelerometers detect interior panel vibrations. The accelerometer signals are fed to the input amplifier where they are conditioned prior to being sent to the ADC. The DSP receives the digitized signals form the ADC, processes these signals, and sends the result to the DAC. The DAC's analog output is used as input to the high voltage power amplifier. The power amplifier drives the PZT actuators to cancel noise form 50 to 1,300 Hz. The specific area of concern for this work was development of a DSP system that could be used for an actual flight demonstration. It was decided to base the system on a commercially available DSP board, the Spectrum Digital eZdsp. This was complicated by the fact that the ADC and DAC capabilities available on the eZdsp board were not sufficient to meet the system specification. Designing and fabricating a special ADC and DAC daughter card for the eZdsp circumvented this problem. The DSP system hardware has been successfully tested and is currently being integrated into the complete noise reduction system. This work has been completed in collaboration with another ASEE Fellow, Dr.William Edmonson from Hampton University and was conducted under the direction of the principle investigator, Dr. Qamar A. Shams of the Instrumentation Systems Development Branch, as part of a continuing noise reduction program.

  3. 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...

  4. 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。

  5. 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。

  6. 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)

  7. 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.

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. Universal control induced by noise

    Science.gov (United States)

    Arenz, Christian; Burgarth, Daniel; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2016-06-01

    On the basis of the quantum Zeno effect, it has been recently shown [D. K. Burgarth et al., Nat. Commun. 5, 5173 (2014), 10.1038/ncomms6173] that a strong-amplitude-damping process applied locally on a part of a quantum system can have a beneficial effect on the dynamics of the remaining part of the system. Quantum operations that cannot be implemented without the dissipation become achievable by the action of the strong dissipative process. Here we generalize this idea by identifying decoherence-free subspaces (DFSs) as the subspaces in which the dynamics becomes more complex. Applying methods from quantum control theory, we characterize the set of reachable operations within the DFSs. We provide three examples that become fully controllable within the DFSs while the control over the original Hilbert space in the absence of dissipation is trivial. In particular, we show that the (classical) Ising Hamiltonian is turned into a Heisenberg Hamiltonian by strong collective decoherence, which provides universal quantum computation within the DFSs. Moreover, we perform numerical gate optimization to study how the process fidelity scales with the noise strength. As a by-product, a subsystem fidelity that can be applied in other optimization problems for open quantum systems is developed.

  13. 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.

  14. 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.

  15. 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...

  16. 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.

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

    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.

  18. 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.

  19. 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.

  20. Active Control of Fan Noise: Feasibility Study. Volume 5; Numerical Computation of Acoustic Mode Reflection Coefficients for an Unflanged Cylindrical Duct

    Science.gov (United States)

    Kraft, R. E.

    1996-01-01

    A computational method to predict modal reflection coefficients in cylindrical ducts has been developed based on the work of Homicz, Lordi, and Rehm, which uses the Wiener-Hopf method to account for the boundary conditions at the termination of a thin cylindrical pipe. The purpose of this study is to develop a computational routine to predict the reflection coefficients of higher order acoustic modes impinging on the unflanged termination of a cylindrical duct. This effort was conducted wider Task Order 5 of the NASA Lewis LET Program, Active Noise Control of aircraft Engines: Feasibility Study, and will be used as part of the development of an integrated source noise, acoustic propagation, ANC actuator coupling, and control system algorithm simulation. The reflection coefficient prediction will be incorporated into an existing cylindrical duct modal analysis to account for the reflection of modes from the duct termination. This will provide a more accurate, rapid computation design tool for evaluating the effect of reflected waves on active noise control systems mounted in the duct, as well as providing a tool for the design of acoustic treatment in inlet ducts. As an active noise control system design tool, the method can be used preliminary to more accurate but more numerically intensive acoustic propagation models such as finite element methods. The resulting computer program has been shown to give reasonable results, some examples of which are presented. Reliable data to use for comparison is scarce, so complete checkout is difficult, and further checkout is needed over a wider range of system parameters. In future efforts the method will be adapted as a subroutine to the GEAE segmented cylindrical duct modal analysis program.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. Retrofitting reciprocating compressors for noise control

    International Nuclear Information System (INIS)

    The Alberta Energy Resources Conservation Board recently enacted their noise control directive ID 88-1. The effects of this regulation on the operation of an oil and gas facility are discussed, and a specific case history is presented to provide a disciplined strategy for noise attenuation retrofits. An investigation was carried out into sound sources at a reciprocating compressor gas plant, revealing several sound sources: engine exhaust stacks, engine exhaust silencer shells, direct-drive fan cooler inlets, direct drive fan cooler outlets, aerial cooler inlets and aerial cooler outlets. Details are presented of the investigative techniques and order-ranking of sources by decibel level. When controlling engine exhaust noise, silencers or mufflers are the preferred treatment. Choice of type (reactive or absorptive) and specification of acoustical performance of a silencer are discussed. The gas plant achieved noise reductions of 6-13 dB, measured at affected residences, through the use of engine exhaust silencers. 4 figs., 2 tabs

  9. Noise control of radiological monitoring equipment

    International Nuclear Information System (INIS)

    Although vacuum pumps on continuous air monitors (CAMs) do not produce noise levels above regulatory limits, engineering controls were used to establish a safer work environment. Operations performed in areas where CAMs are located are highly specialized and require precision work when handling nuclear materials, heavy metals, and inert gases. Traditional methods for controlling noise such as enclosing or isolating the source and the use of personal protection equipment were evaluated. An innovative solution was found by retrofitting CAMs with air powered multistage ejectors pumps. By allowing the air to expand in several chambers to create a vacuum, one can eliminate the noise hazard altogether. In facilities with adequate pressurized air, use of these improved ejector pumps may be a cost-effective replacement for noisy vacuum pumps. A workplace designed or engineered with noise levels as low as possible or as close to background adds to increased concentration, attention to detail, and increased production

  10. 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.

  11. 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.

  12. A case study, noise control for a low frequency noise compliance situation

    Energy Technology Data Exchange (ETDEWEB)

    Farquharson, James; Parent, Michel [CET FDI Acoustics Inc. (Canada)], email: jamesf@fdiacoustics.com, email: mitchp@fdiacoustics.com

    2011-07-01

    The current version of the energy resources conservation board (ERCB) Directive 038: noise control, has recently been modified to include assessment and regulation of low frequency noise. This has led to additional concerns and considerations in noise control measurement. This paper examines a specific example and introduces the low frequency noise assessment and consequent development of noise control measures. Prior to the new Directive 038 regulation, noise compliance in industrial facilities was determined by demonstrating that the sound level in residential areas was beneath a certain threshold, the permissible sound level, fixed by the ERCB. Noise mitigation measures aimed to reduce noise to a point where the overall sound level was below this threshold. With the introduction of low frequency noise considerations, industrials must take into account tonal noise in the low frequency spectrum, using A and C-weighted noise measurements, and third octave band frequency tones, resulting in a new approach for noise control development.

  13. 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.

  14. Noise Control and Noise Evaluation in Aircraft Engines

    OpenAIRE

    石井, 達哉; Ishii, Tatsuya

    2002-01-01

    Aircraft engine noise emitted for example by the jet exhaust, fan, compressor, turbine and combustor is the predominant factor in total aircraft noise during take-off and landing. As a result of enormous efforts to alleviate engine noise, noise levels have been improved by more than 20 dB compared to the first generation of airliners. However, the growing volume of air transport means that further noise reduction is still required. With this background, we decided to concentrate on two techni...

  15. Active noise cancellation in hearing devices

    DEFF Research Database (Denmark)

    2013-01-01

    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...... the generated sound pressure is at least partially corrected for the hearing loss of the user; ; the at least one active noise cancellation unit being adapted to provide an active noise cancellation signal adapted to perform active noise cancellation of an acoustical signal entering the ear canal in addition......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...

  16. 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)

  17. 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.

  18. The Traffic Noise Index: A Method of Controlling Noise Nuisance.

    Science.gov (United States)

    Langdon, F. J.; Scholes, W. E.

    This building research survey is an analysis of the social nuisance caused by urban motor ways and their noise. The Traffic Noise Index is used to indicate traffic noises and their effects on architectural designs and planning, while suggesting the need for more and better window insulation and acoustical barriers. Overall concern is for--(1)…

  19. 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.

  20. 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。

  1. 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.

  2. 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...

  3. 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

  4. Structural Acoustic Prediction and Interior Noise Control Technology

    Science.gov (United States)

    Mathur, G. P.; Chin, C. L.; Simpson, M. A.; Lee, J. T.; Palumbo, Daniel L. (Technical Monitor)

    2001-01-01

    This report documents the results of Task 14, "Structural Acoustic Prediction and Interior Noise Control Technology". The task was to evaluate the performance of tuned foam elements (termed Smart Foam) both analytically and experimentally. Results taken from a three-dimensional finite element model of an active, tuned foam element are presented. Measurements of sound absorption and sound transmission loss were taken using the model. These results agree well with published data. Experimental performance data were taken in Boeing's Interior Noise Test Facility where 12 smart foam elements were applied to a 757 sidewall. Several configurations were tested. Noise reductions of 5-10 dB were achieved over the 200-800 Hz bandwidth of the controller. Accelerometers mounted on the panel provided a good reference for the controller. Configurations with far-field error microphones outperformed near-field cases.

  5. 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。

  6. Noise transmission properties and control strategies for composite structures

    Science.gov (United States)

    Silcox, Richard J.; Beyer, Todd B.; Lester, Harold C.

    1991-01-01

    A study of several component technologies required to apply active control techniques to reduce interior noise in composite aircraft structures is described. The mechanisms of noise transmission in an all composite, large-scale, fuselage model are studied in an experimental program and found similar to mechanisms found in conventional aircraft construction. Two primary conditions of structural acoustic response are found to account for the dominant interior acoustic response. A preliminary study of active noise control in cylinders used piezoceramic actuators as force inputs for a simple aluminum fuselage model. These actuators provided effective control for the same two conditions of noise transmission found in the composite fuselage structure. The use of piezoceramic actuators to apply force inputs overcomes the weight and structural requirements of conventional shaker actuators. Finally, in order to accurately simulate these types of actuators in a cylindrical shell, two analytical models are investigated that apply either in-plane forces or bending moments along the boundaries of a finite patch. It is shown that the bending model may not be as effective as the force model for exciting the low order azimuthal modes that typically dominate the structural acoustic response in these systems. This result will affect the arrangement and distribution of actuators required for effective active control systems.

  7. 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.

  8. Noise control technology for generator sets in enclosures

    Institute of Scientific and Technical Information of China (English)

    Nailong ZHANG; Wentong YANG; Renyuan FEI

    2008-01-01

    Currently, noise pollution is an environmental problem all over the world. The health and life of human beings are affected by loud noise from high power gen-erator sets. To reduce such noise, a sound-attenuated enclosure is widely used for its high performance and con-venient usage. By installing equipment in an enclosure, noise is controlled and prevented from radiating. In this paper, noise control techniques for enclosures are pre-sented. Enclosure development trends are predicted.

  9. 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。

  10. 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.

  11. [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.

  12. 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.

  13. Infinite non-causality in active cancellation of random noise

    CERN Document Server

    Friot, E

    2005-01-01

    Active cancellation of broadband random noise requires the detection of the incoming noise with some time advance. In an duct for example this advance must be larger than the delays in the secondary path from the control source to the error sensor. In this paper it is shown that, in some cases, the advance required for perfect noise cancellation is theoretically infinite because the inverse of the secondary path, which is required for control, can include an infinite non-causal response. This is shown to be the result of two mechanisms: in the single-channel case (one control source and one error sensor), this can arise because of strong echoes in the control path. In the multi-channel case this can arise even in free field simply because of an unfortunate placing of sensors and actuators. In the present paper optimal feedforward control is derived through analytical and numerical computations, in the time and frequency domains. It is shown that, in practice, the advance required for significant noise attenua...

  14. The Feasibility of Noise Control in a Soft Drink Plant

    Directory of Open Access Journals (Sweden)

    Fouladi Dehaghi

    2016-03-01

    Full Text Available Background “Noise” can be defined as any unwanted sound. Soft drink plants, which produce the raw materials used in most carbonated beverage factories, are sources of noise. Objectives This study investigated the noise pollution present in a soft drink CO2 gas injection plant, in order to present noise control measures. Materials and Methods The instructions specified by the canadian center for occupational health and safety (CCOHS were followed during the noise study, and a sound level meter, CEL.450 calibrated with CEL-110.2 based on ISO-9612 methods, was used to record the sound pressure level (SPL at each grid point. SPL was determined in weighting scales A and C. and a noise survey map of equivalent SPLs was drawn for each part. Each part of the floor area of the soft drink factory where SPL exceeded 85 dBA was identified from the noise survey map to determine the causes of high levels of noise. In order to reduce noise level in each part, the absorption coefficient, transmission loss, and noise reduction rate were calculated in the proposed control area. Results According to the study results, noise levels in a CO2 plant’s house and control room ranged from 88 to 102 dB and 79 to 82 dB (A, respectively. In order to reduce the amount of emitted noise in the CO2 plant house and control room, a noise control plan was implemented in each part of the facility; it was met with effective results. Conclusions The findings of this investigation have clearly revealed that plant workers are at risk of developing noise-induced hearing loss. However, after the implementation of a noise control plan in each part of the facility, the noise dose received by workers has significantly decreased. The need to implement a noise conservation program was established.

  15. 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.

  16. 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

  17. 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).

  18. Active compressor engine silencer reduces exhaust noise

    International Nuclear Information System (INIS)

    An active industrial silencer on a compressor engine at a Tenneco Gas station has reduced low-frequency 'rumbling' noise by 8 dB during trials while lowering backpressure about 90$. This 8 dB reduction of the piston firing frequency corresponds to a more than 80% decrease in emitted acoustic power. The silencing unit, installed on one of six engines at the station near Eden, N.Y., continues in operation. Based on the results, the manufacturer is identifying additional compressor sites for further tests. This paper reviews this project

  19. Design and Simulation of Adaptive Active Noise Control System for Aircraft Helmet%飞行头盔主动噪声控制系统的设计及仿真研究

    Institute of Scientific and Technical Information of China (English)

    唐红; 王明皓; 吴凤霞

    2011-01-01

    Aiming at solving low frequency noise existing in cockpit,a design for adaptive active noise control system of aircraft helmet is proposed. Based on it,the filtered-XLMS algoritbm is simulated and analysed using MATLAB.The result shows that the effect of reducing aircraft noise on low frequency is very satisfactory with the scheme.%针对飞机驾驶舱内存在着大量的低频噪声,提出一种应用于飞行员头盔的自适应有源噪声控制系统设计方案,并在此基础上,利用MATLAB对FXLMS算法进行了仿真和性能分析。结果表明,此方案对飞机噪声低频段具有很好的降噪效果。

  20. 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.

  1. 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.

  2. 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.

  3. Perforated fairings for landing gear noise control

    OpenAIRE

    Boorsma, K.; Zhang, X; Molin, N.

    2008-01-01

    Landing gears of commercial aircraft make an important contribution to total aircraft noise in the approach configuration. Using fairings to shield components from high speed impingement reduces noise. Furthermore, perforating these fairings has been confirmed by flight tests to further enable noise reduction. Following a more fundamental study on the application of perforated fairings, a study has been performed to investigate and optimize the benefits of bleeding air through landing gear fa...

  4. 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.

  5. 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.

  6. External noise control in inherently stochastic biological systems.

    Science.gov (United States)

    Zheng, Likun; Chen, Meng; Nie, Qing

    2012-11-01

    Biological systems are often subject to external noise from signal stimuli and environmental perturbations, as well as noises in the intracellular signal transduction pathway. Can different stochastic fluctuations interact to give rise to new emerging behaviors? How can a system reduce noise effects while still being capable of detecting changes in the input signal? Here, we study analytically and computationally the role of nonlinear feedback systems in controlling external noise with the presence of large internal noise. In addition to noise attenuation, we analyze derivatives of Fano factor to study systems' capability of differentiating signal inputs. We find effects of internal noise and external noise may be separated in one slow positive feedback loop system; in particular, the slow loop can decrease external noise and increase robustness of signaling with respect to fluctuations in rate constants, while maintaining the signal output specific to the input. For two feedback loops, we demonstrate that the influence of external noise mainly depends on how the fast loop responds to fluctuations in the input and the slow loop plays a limited role in determining the signal precision. Furthermore, in a dual loop system of one positive feedback and one negative feedback, a slower positive feedback always leads to better noise attenuation; in contrast, a slower negative feedback may not be more beneficial. Our results reveal interesting stochastic effects for systems containing both extrinsic and intrinsic noises, suggesting novel noise filtering strategies in inherently stochastic systems. PMID:23213267

  7. 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)

  8. 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.

  9. 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.

  10. 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.

  11. 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。

  12. 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.

  13. 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.

  14. 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.

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. 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 .

  20. 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.

  1. Aeroacoustics of Flight Vehicles: Theory and Practice. Volume 2: Noise Control

    Science.gov (United States)

    Hubbard, Harvey H. (Editor)

    1991-01-01

    Flight vehicles and the underlying concepts of noise generation, noise propagation, noise prediction, and noise control are studied. This volume includes those chapters that relate to flight vehicle noise control and operations: human response to aircraft noise; atmospheric propagation; theoretical models for duct acoustic propagation and radiation; design and performance of duct acoustic treatment; jet noise suppression; interior noise; flyover noise measurement and prediction; and quiet aircraft design and operational characteristics.

  2. 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.

  3. 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.

  4. 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.

  5. Microwave noise field: active radiometry principles and applications

    Science.gov (United States)

    Polivka, Jiri

    2012-06-01

    Principles of Active Radiometry are presented. Noise radiators are used to generate the low-coherence microwave noise field, and radiometers to evaluate its intensity, polarization and coherence. Several types of noise radiators are described as well as radiometers and antennas. The following applications are introduced: Material evaluation where insertion loss and reflectivity of grainy, irregular and moving objects are preferable. Microwave Coherence Tomography allowing the depth irregularity to be detected in low-loss objects. Near-Field antenna testing, field coherence evaluation, and spatial combining of noise radiators.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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...

  12. 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 (

  13. 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

  14. Process controlled data acquisition in the measurement of noise

    International Nuclear Information System (INIS)

    For the calibration of noise standards the output signal of a standard measuring system has to be recorded and averaged over large time intervals. The output signal is a low-frequency noise signal, which is recorded with a fast data acquisition system, using a Siemens on-line computer. This system is also used for data processing and for the evaluation of parameters to control the standard measuring system. (orig./RW)

  15. 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....

  16. 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

  17. Effects of Noise on Asymmetric Bidirectional Controlled Teleportation

    Science.gov (United States)

    Nie, Yi-you; Sang, Ming-huang

    2016-07-01

    We present a scheme for asymmetric bidirectional controlled teleportation via a six-qubit cluster state in noisy environments, which includes the phase-damping and amplitude-damping channels. We analytically derive the fidelities of the asymmetric bidirectional controlled teleportation process in these two noise channels. We show that the fidelities only depend on the initial state and the noisy rate.

  18. Adjoint-based sensitivity and feedback control of noise emission

    OpenAIRE

    Airiau, Christophe

    2013-01-01

    A LQR control is performed on a reduce order model built from Direct Numerical Simulation of an open cavity flow, for a 2D geometry, and in the aim of controlling noise emission. A -10 dB achievement is demonstrated

  19. 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。

  20. 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 ...

  1. Updating working memory in aircraft noise and speech noise causes different fMRI activations.

    Science.gov (United States)

    Saetrevik, Bjørn; Sörqvist, Patrik

    2015-02-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between "substitution processes," which involve adding new items to the working memory representation and suppressing old items, and "exclusion processes," which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees. PMID:25352319

  2. Controlling low frequency noise using a passive silencer

    Energy Technology Data Exchange (ETDEWEB)

    DeGagne, D.C.; Faszer, A.C. [Noise Solutions Inc., Calgary, AB (Canada)

    2009-07-01

    Nearly 85 per cent of all the oil and natural gas recovered in Canada comes from Alberta where noise emissions from energy facilities are regulated by the Energy Resources Conservation Board (ERCB) and the Alberta Utilities Commission (AUC) through Noise Control Directive D-038. Operators of energy facilities in Alberta must meet the Permissible Sound Level (PSL) established for industrial facilities that are established for receptor locations such as nearby residences. Despite efforts to manage noise, complaints from nearby residents continue to occur even if the facility is in compliance. This is because high and mid frequency components can decay or be absorbed by air and ground conditions leaving mostly low frequency noise (LFN) at the residence. This paper explored the significance of LFN and how some facility operators are dealing with this problem. The impacts of LFN can range from creating a sensation of pressure in the ear, disturbing normal conversation, to creating secondary vibrating effects within homes. If severe enough, it can also result in potential behavioural dysfunction such as task performance deterioration, sleep disturbance and headaches. In 2006, Noise Solutions Inc. was approached by Hunt Oil Company regarding the installation of a new compressor at their Caroline site. The proposal posed a serious noise problem for the community which requested that the new compressor unit be developed without any additional noise impact on the area. Noise Solutions Inc. used a multi-phased approach to develop the most effective LFN silencer using best practical technology and materials. In an effort to fully attenuate both the high frequency noise (dBA) and the low frequency noise (dBC) of the new compressor unit, Noise Solutions and Hunt Oil agreed that a significant level of sound-suppression would be necessary. The entire noise-suppression unit was specially designed to compensate for the sheer size of the compressor building. The first step to

  3. Voice communications in the cockpit noise environment: The role of active noise reduction

    Science.gov (United States)

    Wheeler, Peter David

    The topic of voice communications in the cockpit noise environment of modern fast-jet aircraft and helicopters is addressed, and in particular, research undertaken in support of the development of a system for reducing the noise level at the operators' ear is described by acoustic cancellation within the ear defender, known as active noise reduction (ANR). The internal noise spectra of today's high performance fast-jet aircraft and military helicopters is described, and the complex interaction of acoustic noise transmission, speech, and microphone noise pick-up, which produces the total acoustic environment at the aircrews' ears, is discussed. Means of mathematically modelling the audio channel, quantifying the components identified above, and identifying areas of shortfall in performance are derived, leading to a procedure for the development of attenuation requirements, described as the communications audit. A model of the electroacoustic characteristics of the ANR ear defender assembly is presented and the sound field distribution within the ear defender/ear cavity, and its effect upon cancellation performance, is discussed. The extensive laboratory and flight testing of the ANR system that was undertaken is reviewed, paying particular attention to the measurement and analysis techniques employed in such testing. Finally, the performance characteristics of ANR are discussed and compared with the requirements previously established. Design limitations placed upon the system by the constraints of its area of application are described, and the scope for future improvements is considered.

  4. 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. PMID:27095600

  5. Erratum to "Noise-induced changes of neuronal spontaneous activity in mice inferior colliculus brain slices".

    Science.gov (United States)

    Basta, Dietmar; Ernst, Arne

    2005-02-01

    The inferior colliculus (IC) in vivo is reportedly subject to a noise-induced decrease of GABA-related inhibitory synaptic transmission accompanied by an amplitude increase of auditory evoked responses, a widening of tuning curves and a higher neuronal discharge rate at suprathreshold levels. However, other in vivo experiments which demonstrated constant neuronal auditory thresholds or unchanged spontaneous activity in the IC after noise exposure did not confirm those findings. Perhaps this can be the result of complex noise-induced interactions between different central auditory structures. It was, therefore, the aim of the present study to investigate the effects of noise exposure on the spontaneous electrical activity of single neurons in a slice preparation of the isolated mouse IC. Normal hearing mice were exposed to noise (10 kHz center frequency at 115 dB SPL for 3 h) at the age of 21 days under anesthesia (Ketamin/Rompun 10:1). After one week, auditory brainstem response (ABR) recordings and extracellular single-unit recordings from spontaneously active neurons within the IC slice were performed in noise-exposed and in normal hearing control mice. Noise-exposed animals showed a significant ABR threshold shift in the whole tested frequency range and a significant lower neuronal spontaneous activity in all investigated isofrequency laminae compared to controls. In both groups, the firing rate of 80% of IC neurons (approximately) increased significantly during the application of the GABA(A) receptor antagonist Bicucullin (10 microM). The present findings demonstrate a noise-related modulation of spontaneous activity in the IC, which possibly contribute to the generation of noise-induced tinnitus and hearing loss.

  6. Noise-induced changes of neuronal spontaneous activity in mice inferior colliculus brain slices.

    Science.gov (United States)

    Basta, Dietmar; Ernest, Arne

    2004-09-30

    The inferior colliculus (IC) in vivo is reportedly subject to a noise-induced decrease of GABA-related inhibitory synaptic transmission accompanied by an amplitude increase of auditory evoked responses, a widening of tuning curves and a higher neuronal discharge rate at suprathreshold levels. However, other in vivo experiments which demonstrated constant neuronal auditory thresholds or unchanged spontaneous activity in the IC after noise exposure did not confirm those findings. Perhaps this can be the result of complex noise-induced interactions between different central auditory structures. It was, therefore, the aim of the present study to investigate the effects of noise exposure on the spontaneous electrical activity of single neurons in a slice preparation of the isolated mouse IC. Normal hearing mice were exposed to noise (10 kHz center frequency at 115 dB SPL for 3 h) at the age of 21 days under anesthesia (Ketamin/Rompun 10:1). After one week, auditory brainstem response (ABR) recordings and extracellular single-unit recordings from spontaneously active neurons within the IC slice were performed in noise-exposed and in normal hearing control mice. Noise-exposed animals showed a significant ABR threshold shift in the whole tested frequency range and a significant lower neuronal spontaneous activity in all investigated isofrequency laminae compared to controls. In both groups, the firing rate of 80% of IC neurons (approximately) increased significantly during the application of the GABA(A) receptor antagonist Bicucullin (10 microM). The present findings demonstrate a noise-related modulation of spontaneous activity in the IC, which possibly contribute to the generation of noise-induced tinnitus and hearing loss.

  7. Neural control of helicopter blade-vortex interaction noise

    Science.gov (United States)

    Glaessel, Holger; Kloeppel, Valentin; Rudolph, Stephan

    2001-06-01

    Significant reduction of helicopter blade-vortex interaction (BVI) noise is currently one of the most advanced research topics in the helicopter industry. This is due to the complex flow, the close aerodynamic and structural coupling, and the interaction of the blades with the trailing edge vortices. Analytical and numerical modeling techniques are therefore currently still far from a sufficient degree of accuracy to obtain satisfactory results using classical model based control concepts. Neural networks with a proven potential to learn nonlinear relationships implicitly encoded in a training data set are therefore an appropriate and complementary technique for the alternative design of a nonlinear controller for BVI noise reduction. For nonlinear and adaptive control different neural control strategies have been proposed. Two possible approaches, a direct and an indirect neural controller are described. In indirect neural control, the plant has to be identified first by training a network with measured data. The plant network is then used to train the controller network. On the other hand the direct control approach does not rely on an explicit plant model, instead a specific training algorithm (like reinforcement learning) uses the information gathered from interactions with the environment. In the investigation of the BVI noise phenomena, helicopter developers have undertaken substantial efforts in full scale flight tests and wind tunnel experiments. Data obtained in these experiments have been adequately preprocessed using wavelet analysis and filtering techniques and are then used in the design of a neural controller. Neural open-loop control and neural closed-loop control concepts for the BVI noise reduction problem are conceived, simulated and compared against each other in this work in the above mentioned framework.

  8. Noise and Sound Control in Open Plan Schools.

    Science.gov (United States)

    Schellenberg, Ben

    This annotated bibliography includes summaries of 19 articles and reports dealing with noise control and acoustical design in school buildings. A brief introduction discusses the need for careful attention to acoustics in any school construction or remodeling project, with particular emphasis on the need for special acoustical measures in an open…

  9. 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.

  10. Collisional activation with random noise in ion trap mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    McLuckey, S.A.; Goeringer, D.E.; Glish, G.L. [Oak Ridge National Lab., TN (United States)

    1992-07-01

    Random noise applied to the end caps of a quadrupole ion trap is shown to be an effective means for the collisional activation of trapped ions independent of mass/charge ratio and number of ions. This technique is compared and contrasted with conventional single-frequency collisional activation for the molecular ion of N,N-dimethylaniline, protonated cocaine, the molecular anion of 2,4,6-trinitrotoluene, and doubly protonated neuromedin U-8. Collisional activation with noise tends to produce more extensive fragmentation than the conventional approach due to the fact that product ions are also kinetically excited in the noise experiment. The efficiency of the noise experiment in producing detectable product ions relative to the conventional approach ranges from being equivalent to being a factor of 3 less efficient. Furthermore, discrimination against low mass/charge product ions is apparent in the data from multiply charged biomolecules. Nevertheless, collisional activation with random noise provides a very simple means for overcoming problems associated with the dependence of single-frequency collisional activation on mass/charge ratio and the number of ions in the ion trap. 45 refs., 7 figs.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. When does noise destroy or enhance synchronous behavior in two mutually coupled light-controlled oscillators?

    Science.gov (United States)

    Ramírez Ávila, G M; Kurths, J; Guisset, J L; Deneubourg, J L

    2010-11-01

    We study the influence of white gaussian noise in a system of two mutually coupled light-controlled oscillators (LCOs). We show that under certain noise intensity conditions, noise can destroy or enhance synchronization. We build some Arnold tonguelike structures in order to explain the effects due to noise. It is remarkable that noise-enhanced synchronization is possible only when the variances of the noise acting on each of the LCOs are different.

  17. Aeroacoustic control of landing gear noise using perforated fairings

    OpenAIRE

    Boorsma, Koen

    2008-01-01

    A study was performed to investigate and optimize the application of perforated fairings for landing gear noise control. The sparse knowledge about this new subject has necessitated a more fundamental study involving a basic fairing-strut configuration, followed by wind tunnel tests on a simplified landing gear configuration incorporating perforated fairings. For the basic configuration, various exchangeable perforated half-cylindrical shells shrouding a circular cylinder we...

  18. 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.

  19. 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.

  20. 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.

  1. Noise influence on spike activation in a Hindmarsh–Rose small-world neural network

    Science.gov (United States)

    Zhe, Sun; Micheletto, Ruggero

    2016-07-01

    We studied the role of noise in neural networks, especially focusing on its relation to the propagation of spike activity in a small sized system. We set up a source of information using a single neuron that is constantly spiking. This element called initiator x o feeds spikes to the rest of the network that is initially quiescent and subsequently reacts with vigorous spiking after a transitional period of time. We found that noise quickly suppresses the initiator’s influence and favors spontaneous spike activity and, using a decibel representation of noise intensity, we established a linear relationship between noise amplitude and the interval from the initiator’s first spike and the rest of the network activation. We studied the same process with networks of different sizes (number of neurons) and found that the initiator x o has a measurable influence on small networks, but as the network grows in size, spontaneous spiking emerges disrupting its effects on networks of more than about N = 100 neurons. This suggests that the mechanism of internal noise generation allows information transmission within a small neural neighborhood, but decays for bigger network domains. We also analyzed the Fourier spectrum of the whole network membrane potential and verified that noise provokes the reduction of main θ and α peaks before transitioning into chaotic spiking. However, network size does not reproduce a similar phenomena; instead we recorded a reduction in peaks’ amplitude, a better sharpness and definition of Fourier peaks, but not the evident degeneration to chaos observed with increasing external noise. This work aims to contribute to the understanding of the fundamental mechanisms of propagation of spontaneous spiking in neural networks and gives a quantitative assessment of how noise can be used to control and modulate this phenomenon in Hindmarsh‑Rose (H‑R) neural networks.

  2. Analysis of noise characteristics for the active pixels in CMOS image sensors for X-ray imaging

    Science.gov (United States)

    Kim, Young Soo; Cho, Gyuseong; Bae, Jun-Hyung

    2006-09-01

    CMOS image sensors have poorer performance compared to conventional charge coupled devices (CCDs). Since CMOS Active Pixel Sensors (APSs) in general have higher temporal noise, higher dark current, smaller full well charge capacitance, and lower spectral response, they cannot provide the same wide dynamic range and superior signal to noise ratio as CCDs. In view of electronic noise, the main source for the CMOS APS is the pixel, along with other signal processing blocks such as row and column decoder, analog signal processor (ASP), analog-to-digital converter (ADC), and timing and control logic circuitry. Therefore, it is important and necessary to characterize noise of the active pixels in CMOS APSs, and we performed experimental measurements and comparisons with theoretical estimations. To derive noise source of the pixels, we designed and fabricated four types of CMOS active pixels, and each pixel is composed of a photodiode and three MOS transistors. The size of these pixels is 100 μm×100 μm. The test chip was fabricated using ETRI 0.8 μm (2P/2M) standard CMOS process. It was found that the dominant noise in CMOS active pixels is shot noise during integration under normal operating conditions. And, it was also seen that epitaxial type pixels have similar noise level compared to non-epitaxial type, and the noise of diffusion type pixel is larger than for a well type pixel on the same substrate type.

  3. Analysis of noise characteristics for the active pixels in CMOS image sensors for X-ray imaging

    International Nuclear Information System (INIS)

    CMOS image sensors have poorer performance compared to conventional charge coupled devices (CCDs). Since CMOS Active Pixel Sensors (APSs) in general have higher temporal noise, higher dark current, smaller full well charge capacitance, and lower spectral response, they cannot provide the same wide dynamic range and superior signal to noise ratio as CCDs. In view of electronic noise, the main source for the CMOS APS is the pixel, along with other signal processing blocks such as row and column decoder, analog signal processor (ASP), analog-to-digital converter (ADC), and timing and control logic circuitry. Therefore, it is important and necessary to characterize noise of the active pixels in CMOS APSs, and we performed experimental measurements and comparisons with theoretical estimations. To derive noise source of the pixels, we designed and fabricated four types of CMOS active pixels, and each pixel is composed of a photodiode and three MOS transistors. The size of these pixels is 100 μmx100 μm. The test chip was fabricated using ETRI 0.8 μm (2P/2M) standard CMOS process. It was found that the dominant noise in CMOS active pixels is shot noise during integration under normal operating conditions. And, it was also seen that epitaxial type pixels have similar noise level compared to non-epitaxial type, and the noise of diffusion type pixel is larger than for a well type pixel on the same substrate type

  4. 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...

  5. Noise-controlled bistability in an excitable system with positive feedback

    Science.gov (United States)

    Kromer, Justus A.; Pinto, Reynaldo D.; Lindner, Benjamin; Schimansky-Geier, Lutz

    2014-10-01

    We study the interplay between noise and a positive feedback mechanism in an excitable system that generates events. We show that such a system can exhibit a bistability in the dynamics of the event generation (states of low and high activity). The stability of the two states is determined by the strength of the noise such that a change of noise intensity permits complete control over the probabilities with which the two states are occupied. The bistability also has strong implications for the regularity of the event generation. While the irregularity of the interevent interval (short-time variability) and the asymptotic Fano factor of the event count (long-time variability) are limited if the system is only in one of the two states, we show that both measures of variability display giant values if both states are equally likely. The long-time variability is additionally amplified by long-range positive correlations of the interevent intervals.

  6. 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.

  7. 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......, measurements of the general office noise levels and the room acoustic conditions according to ISO 3382-3 have been carried out in five open plan offices. Probability density functions of the sound pressure level have been obtained, and the human activity noise has been identified. Results showed a decrease in...... 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....

  8. 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 ...

  9. Industrial wideband noise reduction for hearing aids using a headset with adaptive-feedback active noise cancellation.

    Science.gov (United States)

    Lin, J H; Li, P C; Tang, S T; Liu, P T; Young, S T

    2005-11-01

    High-intensity noises are a health hazard for industrial workers, and hearing protection is necessary to prevent hearing loss. Passive methods, such as ear muffs, are ineffective against low-frequency noise. Moreover, many hearing-impaired workers must wear hearing aids to enable communication at their workplace, and such aids can amplify ambient noise. To overcome this problem, the present study developed a headset equipped with a digital signal processing system to implement adaptive-feedback active noise cancellation (AFANC) to reduce low-frequency noise. The proposed AFANC headset was effective against wideband industrial noise, with a maximum noise spectrum power reduction of 30 dB. Furthermore, when used with a hearing aid, it improved the speech signal-to-noise ratio by up to 14 dB. These results suggest that a headset with AFANC would be useful for hearing protection in workplaces with high levels of low-frequency industrial noise, especially for hearing-impaired workers. PMID:16594300

  10. Distinct noise-controlling roles of multiple negative feedback mechanisms in a prokaryotic operon system.

    Science.gov (United States)

    Nguyen, L K; Kulasiri, D

    2011-03-01

    Molecular fluctuations are known to affect dynamics of cellular systems in important ways. Studies aimed at understanding how molecular systems of certain regulatory architectures control noise therefore become essential. The interplay between feedback regulation and noise has been previously explored for cellular networks governed by a single negative feedback loop. However, similar issues within networks consisting of more complex regulatory structures remain elusive. The authors investigate how negative feedback loops manage noise within a biochemical cascade concurrently governed by multiple negative feedback loops, using the prokaryotic tryptophan (trp) operon system in Escherechia coli as the model system. To the authors knowledge, this is the first study of noise in the trp operon system. They show that the loops in the trp operon system possess distinct, even opposing, noise-controlling effects despite their seemingly analogous feedback structures. The enzyme inhibition loop, although controlling the last reaction of the cascade, was found to suppress noise not only for the tryptophan output but also for other upstream components. In contrast, the Repression (Rep) loop enhances noise for all systems components. Attenuation (Att) poses intermediate effects by attenuating noise for the upstream components but promoting noise for components downstream of its target. Regarding noise at the output tryptophan, Rep and Att can be categorised as noise-enhancing loops whereas Enzyme Inhibition as a noise-reducing loop. These findings suggest novel implications in how cellular systems with multiple feedback mechanisms control noise. [Includes supplementary material]. PMID:21405203

  11. Amplitude noise in passively and actively operated masers

    International Nuclear Information System (INIS)

    A calculation of the power spectral density of amplitude fluctuations in masers is presented, which gives results in close agreement with others. The maximum of this power spectral density, which appears in specified conditions, for a Fourier frequency related to the Rabi frequency of atoms is observed for the first time both in a hydrogen and a rubidium maser. The given model is completed to include a coherent excitation, as required in passively operated masers. Two methods for the interrogation of the atoms are considered. In the first one, the maximum of the atomic emission line is probed and in the second one, the null of the atomic dispersion line is observed. The power spectral density of fractional frequency fluctuations of the slaved frequency generator is calculated in both cases, including the effect of thermal noise in the microwave cavity and of noise added by the microwave receiver. Optimum operating conditions are specified. The cavity pulling factor is specified for both methods of interrogation and the effect of noise in the control of the microwave cavity resonant frequency is considered. Finally a useful design criterion is given for passively operated masers

  12. 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.

  13. Active Vibration Control of Axial Piston Machine using Higher Harmonic Least Mean Square Control of Swash Plate

    OpenAIRE

    Kim, Taeho; Ivantysynova, Monika

    2016-01-01

    Noise emission is a major drawback of the positive displacement machine. The noise source can be divided into structure borne noise source (SBNS) and fluid borne noise source (FBNS). Passive techniques such as valve plate optimization have been used for noise reduction of axial piston machines. However, passive techniques are only effective for limited operating conditions or at least need compromises in design. In this paper, active vibration control of swash plate is investigated for vibrat...

  14. 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.

  15. 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...... permissible Danish noise exposure levels are based will be explained. ISO 1996, 1st edition 1971, has played a decisive part. The maximum permissible Danish noise exposure levels for external industrial noise are strict and enforced for new plants and in connection with enlargement of existing plants....... 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....

  16. Three-Party Controlled Quantum Teleportation with Six-Photon Entangled States via Collective Noise Channel

    International Nuclear Information System (INIS)

    Two three-party controlled quantum teleportation protocols using six-photon entangled states are proposed for circumventing collective noise. It can be performed in collective-dephasing noise or collective-rotation noise with unitary successful probability. Due to the symmetry of the quantum channel, each participant can act as a sender, a receiver or a controller. Moreover, it can be generalized to multiparty controlled teleportation protocols. (authors)

  17. 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.

  18. 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.

  19. A noise control package for vibrating screens1),2)

    OpenAIRE

    Lowe, M. Jenae; Yantek, David S.; Yang, Junyi; Schuster, Kevin C.; Mechling, Jessie J.

    2013-01-01

    Hearing loss was the second-most common illness reported to the Mine Safety and Health Administration (MSHA) in 2009. Furthermore, between 2000 and 2010, 30% of all noise-related injury complaints reported to MSHA were for coal preparation plant employees. Previous National Institute for Occupational Safety and Health (NIOSH) studies have shown that vibrating screens are key noise sources to address in order to reduce coal preparation plant noise. In response, NIOSH researchers have developed...

  20. '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.

  1. 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.

  2. 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.

  3. Updating working memory in aircraft noise and speech noise causes different fMRI activations

    OpenAIRE

    Sætrevik, Bjørn; Sörqvist, Patrik

    2014-01-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between “substitution processes,” which involve adding new items to the working memory representation and suppressing old items, and “exclusion processes,” which involve rejecting new items and maintaining an intact memory set. The cu...

  4. 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.

  5. Noise focusing and the emergence of coherent activity in neuronal cultures

    Science.gov (United States)

    Orlandi, Javier G.; Soriano, Jordi; Alvarez-Lacalle, Enrique; Teller, Sara; Casademunt, Jaume

    2013-09-01

    At early stages of development, neuronal cultures in vitro spontaneously reach a coherent state of collective firing in a pattern of nearly periodic global bursts. Although understanding the spontaneous activity of neuronal networks is of chief importance in neuroscience, the origin and nature of that pulsation has remained elusive. By combining high-resolution calcium imaging with modelling in silico, we show that this behaviour is controlled by the propagation of waves that nucleate randomly in a set of points that is specific to each culture and is selected by a non-trivial interplay between dynamics and topology. The phenomenon is explained by the noise focusing effect--a strong spatio-temporal localization of the noise dynamics that originates in the complex structure of avalanches of spontaneous activity. Results are relevant to neuronal tissues and to complex networks with integrate-and-fire dynamics and metric correlations, for instance, in rumour spreading on social networks.

  6. 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.

  7. 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

  8. 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.

  9. Improving postural control by applying mechanical noise to ankle muscle tendons.

    Science.gov (United States)

    Borel, Liliane; Ribot-Ciscar, Edith

    2016-08-01

    The application of subthreshold mechanical vibrations with random frequencies (white mechanical noise) to ankle muscle tendons is known to increase muscle proprioceptive information and to improve the detection of ankle movements. The aim of the present study was to analyze the effect of this mechanical noise on postural control, its possible modulation according to the sensory strategies used for postural control, and the consequences of increasing postural difficulty. The upright stance of 20 healthy young participants tested with their eyes closed was analyzed during the application of four different levels of noise and compared to that in the absence of noise (control) in three conditions: static, static on foam, and dynamic (sinusoidal translation). The quiet standing condition was conducted with the eyes open and closed to determine the subjects' visual dependency to maintain postural stability. Postural performance was assessed using posturographic and motion analysis evaluations. The results in the static condition showed that the spectral power density of body sway significantly decreased with an optimal level of noise and that the higher the spectral power density without noise, the greater the noise effect, irrespective of visual dependency. Finally, noise application was ineffective in the foam and dynamic conditions. We conclude that the application of mechanical noise to ankle muscle tendons is a means to improve quiet standing only. These results suggest that mechanical noise stimulation may be more effective in more impaired populations. PMID:27021075

  10. 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

  11. Control of linear accelerator noise in the Los Alamos free-electron laser (FEL)

    International Nuclear Information System (INIS)

    The Los Alamos FEL requires tight control of the amplitudes and phases of the fields in two linear accelerator tanks to obtain stable lasing. The accelerator control loops must establish constant, stable, repeatable amplitudes and phases of the rf fields and must have excellent bandwidth to control high-frequency noise components. A model of the feedback loops has been developed that agrees well with measurements and allows easy substitution of components and circuits, thus reducing breadboarding requirements. The model permits both frequency and time-domain analysis. This paper describes the accelerator control scheme and our model and discusses the control of noise in feedback loops, showing how low-frequency-noise components (errors) can be corrected, but high-frequency-noise components (errors) are actually amplified by the feedback circuit. Measurements of noise in both open- and closed-loop modes are shown and comparison is made with results from the model calculations

  12. 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. PMID:21196059

  13. Active control of transmitted sound in buildings

    Science.gov (United States)

    Thompsett, Russell Harvey George

    The problem of noise from neighbours has increased dramatically over the last few years. Many of the noise complaints are due to the high level, low frequency noise from modern stereo equipment, and are often described in terms of the low frequency characteristics of the music; the repetitive, booming, bass beat. The objective of this research was to establish the feasibility of applying active noise control to alleviate this problem. The initial approach was to evaluate the possibility of exploiting the dominance of individual modes in the response of rooms at low frequency to effect global control. However, initial investigations using a modal model of the sound field revealed that this would be difficult due to the contribution of many acoustic modes excited off resonance. This conclusion was supported by measurements of acoustic room responses in typical buildings, illustrating a non-resonant characteristic. Consequently, attention was turned to the feasibility of using local active control systems to create zones of quiet by concentrating control at a specific location near the observers ears, for example in a seat headrest, or near the pillows of a bed. The lack of a reference signal in either approach requires the use of a feedback control strategy. With a typically non-resonant system, the predictability in the disturbance necessary for successful feedback control must be contained in the primary excitation, namely the music. Examples of different music styles were investigated and of those with the potential to be a nuisance surprisingly few were significantly more predictable than a random disturbance. As expected the most encouraging control performance simulations were found for modern dance music, with a strong repetitive beat. A real-time, local controller was demonstrated in the laboratory with such a disturbance signal and the properties of the quiet zone were measured. The subjective response when hearing the controller in operation was found to be

  14. 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.

  15. Delayed feedback as a means of control of noise-induced motion

    OpenAIRE

    Janson, N. B.; A. G. Balanov; Schoell, E.

    2003-01-01

    Time--delayed feedback is exploited for controlling noise--induced motion in coherence resonance oscillators. Namely, under the proper choice of time delay, one can either increase or decrease the regularity of motion. It is shown that in an excitable system, delayed feedback can stabilize the frequency of oscillations against variation of noise strength. Also, for fixed noise intensity, the phenomenon of entrainment of the basic oscillation period by the delayed feedback occurs. This allows ...

  16. 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.

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

    NARCIS (Netherlands)

    Diniz, A.; Wijnants, M.L.; Torre, K.; Barreiros, J.; Crato, N.; Bosman, A.M.T.; Hasselman, F.; Cox, R.F.A.; Orden, G.C. van; Delignieres, D.

    2011-01-01

    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

  18. A theoretical and experimental study of wood planer noise and its control

    Science.gov (United States)

    Stewart, J. S.

    1972-01-01

    A combined analytical and experimental study of wood planer noise is made and the results applied to the development of practical noise control techniques. The dominant mechanisms of sound generation are identified and an analysis is presented which accurately predicts the governing levels of noise emission. Planing operations in which the length of the board is much greater than the width are considered. The dominant source of planer noise is identified as the board being surfaced, which is set into vibration by the impact of cutterhead knives. This is determined from studies made both in the laboratory and in the field concerning the effect of board width on the resulting noise, which indicate a six decibel increase in noise level for each doubling of board width. The theoretical development of a model for board vibration defines the vibrational field set up in the board and serves as a guide for cutterhead redesign.

  19. Industrial Noise

    OpenAIRE

    Mehran zolfaghari

    1996-01-01

    Various risk factors in industrial environments can affect hearing status and healthy in today’s modern society. Noise control and hearing conservation program is very crucial in preventing workers exposed to high levels of noise in the work places. In the current article we are going to discuss issues such as industrial noise control, noise characteristics and standards and techniques for noise control. Then the methods for individual hearing conservation and medical care will be described i...

  20. Active Fluid Borne Noise Reduction for Aviation Hydraulic Pumps

    OpenAIRE

    Waitschat, Arne; Thielecke, Frank; Behr, Robert M.; Heise, Ulrich

    2016-01-01

    The aviation environment holds challenging application constraints for efficient hydraulic system noise reduction devices. Besides strong limits on component weight and size, high safety and reliability standards demand simple solutions. Hence, basic silencers like inline expansion chambers and Helmholtz-Resonators are state-of-the-art aboard commercial aircrafts. Unfortunately, they do not meet today’s noise attenuation aims regarding passenger comfort and equipment durability. Significant a...

  1. Active control of smart structures : an overall approach

    OpenAIRE

    Nestorović Tamara; Trajkov Miroslav

    2010-01-01

    The paper presents active control of smart structures within a focused frame of piezoelectric applications in active vibration and noise attenuation with potentials for the use in mechanical and civil engineering. An overall approach to active control of piezoelectric structures involves subsequent steps of modeling, control, simulation, experimental verification and implementation. Each of these steps is regarded in details. Different application examples showing the feasibility of the activ...

  2. 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.

  3. 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.

  4. Foundations of Active Control - Active Noise Reduction Helmets

    DEFF Research Database (Denmark)

    Elmkjær, Torsten Haaber Leth

    2008-01-01

    includes a number of coherence analysis that are based on diffuse sound field measurements in a reverberant chamber and measurements conducted onboard a CH-47D Chinook helicopter. From these coherence analysis it can be concluded that the CFFAC system with 10 reference sensors applied to pilot helmets...... with no obvious input and output channel definition by a finite lumped-elements multi-channel system. Usually, no unique transfer function x exist as the system is not point-wise excited, but excited over an area as in the case of diffuse sound field illumination. A new method for acoustical signal processing...... on a head and torso simulator (HATS), is exposed to diffuse sound field illumination. By applying the JCRSA method the spatially-weighted-averaged acquisition lead times provided by the reference sensors relative to the performance sensors are estimated to be as much as 800-900μs. The thesis also includes...

  5. A Kalman filter for feedback control of rotating external kink instabilities in the presence of noise

    International Nuclear Information System (INIS)

    The simulation and experimental optimization of a Kalman filter feedback control algorithm for n=1 tokamak external kink modes are reported. In order to achieve the highest plasma pressure limits in ITER, resistive wall mode stabilization is required [T. C. Hender et al., Nucl. Fusion 47, S128 (2007)] and feedback algorithms will need to distinguish the mode from noise due to other magnetohydrodynamic activity. The Kalman filter contains an internal model that captures the dynamics of a rotating, growing n=1 mode. This model is actively compared with real-time measurements to produce an optimal estimate for the mode's amplitude and phase. On the High Beta Tokamak-Extended Pulse experiment [T. H. Ivers et al., Phys. Plasmas 3, 1926 (1996)], the Kalman filter algorithm is implemented using a set of digital, field-programmable gate array controllers with 10 μs latencies. Signals from an array of 20 poloidal sensor coils are used to measure the n=1 mode, and the feedback control is applied using 40 poloidally and toroidally localized control coils. The feedback system with the Kalman filter is able to suppress the external kink mode over a broad range of phase angles between the sensed mode and applied control field. Scans of filter parameters show good agreement between simulation and experiment, and feedback suppression and excitation of the kink mode are enhanced in experiments when a filter made using optimal parameters from the scans is used.

  6. THACO, a Test Facility for Characterizing the Noise Performance of Active Antenna Arrays

    CERN Document Server

    Woestenburg, E E M; Ruiter, M; Ivashina, M V; Witvers, R H

    2011-01-01

    This paper discusses an outdoor test facility for the noise characterization of active antenna arrays, using measurement results of array noise temperatures in the order of 50 K for a number of small aperture arrays. The measurement results are obtained by a Y-factor method with hot and a cold noise sources, with an absorber at room temperature as the hot load and the cold sky as the cold load. The effect of shielding the arrays by the test facility, with respect to noise and RFI from the environment, will also be discussed.

  7. A noise filtering algorithm for the MFTF-B computer based control system

    International Nuclear Information System (INIS)

    An algorithm to reduce the message traffic in the MFTF-B computer based control system is described. The algorithm filters analog inputs to the control system. Its purpose is to distinguish between changes in the inputs due to noise and changes due to significant variations in the quantity being monitored. Noise is rejected while significant changes are reported to the control system data base, thus keeping the data base updated with a minimum number of messages. The algorithm is memory efficient, requiring only four bytes of storage per analog channel, and computationally simple, requiring only subtraction and comparison. Quantitative analysis of the algorithm is presented for the case of additive Gaussian noise. It is shown that the algorithm is stable and tends toward the mean value of the monitored variable over a wide variety of additive noise distributions

  8. Noise filtering algorithm for the MFTF-B computer based control system

    International Nuclear Information System (INIS)

    An algorithm to reduce the message traffic in the MFTF-B computer based control system is described. The algorithm filters analog inputs to the control system. Its purpose is to distinguish between changes in the inputs due to noise and changes due to significant variations in the quantity being monitored. Noise is rejected while significant changes are reported to the control system data base, thus keeping the data base updated with a minimum number of messages. The algorithm is memory efficient, requiring only four bytes of storage per analog channel, and computationally simple, requiring only subtraction and comparison. Quantitative analysis of the algorithm is presented for the case of additive Gaussian noise. It is shown that the algorithm is stable and tends toward the mean value of the monitored variable over a wide variety of additive noise distributions

  9. Resonant-Like Activation in a Bistable System with Noise and Time Delay

    Institute of Scientific and Technical Information of China (English)

    NIE Lin-Ru; GONG Ai-Ling; MEI Dong-Cheng

    2009-01-01

    A bistable system with noise and time delay is investigated.Theoretical analysis and stochastic simulation show that:(i) In the case of a system driven only by multiplicative Gaussian white noise,the mean first-passage time for a particle to reach the other stable state from one stable state exhibits a minimum with respect to delay time,i.e.,a resonant-like activation (RA) phenomenon.(ii) In the action of additive and multiplicative noise,as the additive noise intensity increases,no matter whether a correlation between the two types of noise exists or not,the RA gradually disappears.(iii) The correlation strength between the two types of noise does not influence the existence of the RA.

  10. Low noise frequency synthesizer with self-calibrated voltage controlled oscillator and accurate AFC algorithm

    International Nuclear Information System (INIS)

    A low noise phase locked loop (PLL) frequency synthesizer implemented in 65 nm CMOS technology is introduced. A VCO noise reduction method suited for short channel design is proposed to minimize PLL output phase noise. A self-calibrated voltage controlled oscillator is proposed in cooperation with the automatic frequency calibration circuit, whose accurate binary search algorithm helps reduce the VCO tuning curve coverage, which reduces the VCO noise contribution at PLL output phase noise. A low noise, charge pump is also introduced to extend the tuning voltage range of the proposed VCO, which further reduces its phase noise contribution. The frequency synthesizer generates 9.75–11.5 GHz high frequency wide band local oscillator (LO) carriers. Tested 11.5 GHz LO bears a phase noise of−104 dBc/Hz at 1 MHz frequency offset. The total power dissipation of the proposed frequency synthesizer is 48 mW. The area of the proposed frequency synthesizer is 0.3 mm2, including bias circuits and buffers. (semiconductor integrated circuits)

  11. Electromyographic Activity in the EEG in Alzheimer's Disease: Noise or Signal?

    Directory of Open Access Journals (Sweden)

    Karin van der Hiele

    2011-01-01

    Full Text Available Many efforts have been directed at negating the influence of electromyographic (EMG activity on the EEG, especially in elderly demented patients. We wondered whether these “artifacts” might reflect cognitive and behavioural aspects of dementia. In this pilot study, 11 patients with probable Alzheimer's disease (AD, 13 with amnestic mild cognitive impairment (MCI and 13 controls underwent EEG registration. As EMG measures, we used frontal and temporal 50–70 Hz activity. We found that the EEGs of AD patients displayed more theta activity, less alpha reactivity, and more frontal EMG than controls. Interestingly, increased EMG activity indicated more cognitive impairment and more depressive complaints. EEG variables on the whole distinguished better between groups than EMG variables, but an EMG variable was best for the distinction between MCI and controls. Our results suggest that EMG activity in the EEG could be more than noise; it differs systematically between groups and may reflect different cerebral functions than the EEG.

  12. 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.

  13. 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.

  14. 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.

  15. Transient finite element simulations and experiments on active control of sound transmission loss through plates

    OpenAIRE

    Brink, Maarten Cornelis

    2008-01-01

    In this thesis the sound transmission loss of a plate has been investigated. It serves as an abstract model for the noise barrier between engine and passengers in a bus. A finite element simulation model has been developed to be able to predict the plate's noise reduction effect. To increase this reduction without adding too much mass, the integration of active noise control (ANC) has been investigated. The active system contained a controller, microphones and piezoelectric actuators. The inf...

  16. Real-time shot-noise-limited differential photodetection for atomic quantum control

    CERN Document Server

    Ciurana, F Martin; Sewell, Robert J; Mitchell, M W

    2016-01-01

    We demonstrate high-efficiency, shot-noise-limited differential photodetection with real-time signal conditioning, suitable for feedback-based quantum control of atomic systems. The detector system has quantum efficiency of 0.92, is shot-noise limited from 7.4 x 10^5 to 3.7 x 10^8 photons per pulse, and provides real-time voltage-encoded output at up to 2.3 Mpulses per second.

  17. Distinct noise-controlling roles of multiple negative feedback mechanisms in a prokaryotic operon system

    OpenAIRE

    Nguyen, Lan K.; D. Kulasiri

    2011-01-01

    Molecular fluctuations are known to affect dynamics of cellular systems in important ways. Studies aimed at understanding how molecular systems of certain regulatory architectures control noise therefore become essential. The interplay between feedback regulation and noise has been previously explored for cellular networks governed by a single negative feedback loop. However, similar issues within networks consisting of more complex regulatory structures remain elusive. The authors investigat...

  18. Noise-induced cooperative dynamics and its control in coupled neuron models

    OpenAIRE

    Hauschildt, B.; Janson, N. B.; Balanov, A.; Schoell, E.

    2006-01-01

    We investigate feedback control of the cooperative dynamics of two coupled neural oscillators that is induced merely by external noise. The interacting neurons are modelled as FitzHugh-Nagumo systems with parameter values at which no autonomous oscillations occur, and each unit is forced by its own source of random fluctuations. Application of delayed feedback to only one of two subsystems is shown to be able to change coherence and timescales of noise induced oscillations either in the given...

  19. The effect of human activities and their associated noise on ungulate behavior.

    Directory of Open Access Journals (Sweden)

    Casey L Brown

    Full Text Available BACKGROUND: The effect of anthropogenic noise on terrestrial wildlife is a relatively new area of study with broad ranging management implications. Noise has been identified as a disturbance that has the potential to induce behavioral responses in animals similar to those associated with predation risk. This study investigated potential impacts of a variety of human activities and their associated noise on the behavior of elk (Cervus elaphus and pronghorn (Antilocapra americana along a transportation corridor in Grand Teton National Park. METHODOLOGY/PRINCIPAL FINDINGS: We conducted roadside scan surveys and focal observations of ungulate behavior while concurrently recording human activity and anthropogenic noise. Although we expected ungulates to be more responsive with greater human activity and noise, as predicted by the risk disturbance hypothesis, they were actually less responsive (less likely to perform vigilant, flight, traveling and defensive behaviors with increasing levels of vehicle traffic, the human activity most closely associated with noise. Noise levels themselves had relatively little effect on ungulate behavior, although there was a weak negative relationship between noise and responsiveness in our scan samples. In contrast, ungulates did increase their responsiveness with other forms of anthropogenic disturbance; they reacted to the presence of pedestrians (in our scan samples and to passing motorcycles (in our focal observations. CONCLUSIONS: These findings suggest that ungulates did not consistently associate noise and human activity with an increase in predation risk or that they could not afford to maintain responsiveness to the most frequent human stimuli. Although reduced responsiveness to certain disturbances may allow for greater investment in fitness-enhancing activities, it may also decrease detections of predators and other environmental cues and increase conflict with humans.

  20. 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.

  1. Adaptive noise

    OpenAIRE

    Viney, Mark; Reece, Sarah E.

    2013-01-01

    In biology, noise implies error and disorder and is therefore something which organisms may seek to minimize and mitigate against. We argue that such noise can be adaptive. Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells. Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise ...

  2. 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.

  3. Resonant Activation in a Stochastic Hodgkin-Huxley Model: Interplay between noise and suprathreshold driving effect

    DEFF Research Database (Denmark)

    Pankratova, Evgeniya; Polovinkin, A.V.; Mosekilde, Erik

    2005-01-01

    The paper considers an excitable Hodgkin-Huxley system subjected to a strong periodic forcing in the presence of random noise. The influence of the forcing frequency on the response of the system is examined in the realm of suprathreshold amplitudes. Our results confirm that the presence of noise...... has a detrimental effect on the neuronal response. Fluctuations can induce significant delays in the detection of an external signal. We demonstrate, however, that this negative influence may be minimized by a resonant activation effect: Both the mean escape time and its standard deviation exhibit...... a minimum as functions of the forcing frequency. The destructive influence of noise on the interspike interval can also be reduced. With driving signals in a certain frequency range, the system can show stable periodic spiking even for relatively large noise intensities. Outside this frequency range, noise...

  4. 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.

  5. Screening of Potential Landing Gear Noise Control Devices at Virginia Tech For QTD II Flight Test

    Science.gov (United States)

    Ravetta, Patricio A.; Burdisso, Ricardo A.; Ng, Wing F.; Khorrami, Mehdi R.; Stoker, Robert W.

    2007-01-01

    In support of the QTD II (Quiet Technology Demonstrator) program, aeroacoustic measurements of a 26%-scale, Boeing 777 main landing gear model were conducted in the Virginia Tech Stability Tunnel. The objective of these measurements was to perform risk mitigation studies on noise control devices for a flight test performed at Glasgow, Montana in 2005. The noise control devices were designed to target the primary main gear noise sources as observed in several previous tests. To accomplish this task, devices to reduce noise were built using stereo lithography for landing gear components such as the brakes, the forward cable harness, the shock strut, the door/strut gap and the lower truck. The most promising device was down selected from test results. In subsequent stages, the initial design of the selected lower truck fairing was improved to account for all the implementation constraints encountered in the full-scale airplane. The redesigned truck fairing was then retested to assess the impact of the modifications on the noise reduction potential. From extensive acoustic measurements obtained using a 63-element microphone phased array, acoustic source maps and integrated spectra were generated in order to estimate the noise reduction achievable with each device.

  6. Controlled Dephasing of Electrons by Non-Gaussian Shot Noise

    OpenAIRE

    Neder, I.; Marquardt, F.; Heiblum, M.; Mahalu, D.; Umansky, V

    2006-01-01

    In a 'controlled dephasing' experiment [1-3], an interferometer loses its coherence due to entanglement with a controlled quantum system ('which path' detector). In experiments that were conducted thus far in mesoscopic systems only partial dephasing was achieved. This was due to weak interactions between many detector electrons and the interfering electron, resulting in a Gaussian phase randomizing process [4-10]. Here, we report the opposite extreme: a complete destruction of the interferen...

  7. 强噪声环境下有源抗噪耳罩设计%Design of active anti-noise earmuffs in heavy noise environment

    Institute of Scientific and Technical Information of China (English)

    孙科伟; 李建海; 杨海东; 宋博

    2013-01-01

    In view of problems of expensive and inconvenient to wear of existing active anti-noise earmuffs,an active anti-noise earmuff in heavy noise environment was designed.The earmuff takes TMS320VC5509 as processor,and adopts adaptive noise cancellation method and the normalized least mean square algorithm to enhance adaptive noise cancellation performance.Combined with passive noise reduction technology,the earmuff realizes purpose of noise cancellation in heavy noise environment.The experimental results show that anti-noise performance of the earmuffs is up to 30 dB.%针对现有的有源抗噪耳罩存在价格昂贵且佩戴不太方便的问题,设计了一种应用在强噪声环境下的有源抗噪耳罩.该耳罩以TMS320VC5509为主控芯片,采用自适应噪声抵消方案和归一化的最小均方算法提升耳罩的自适应噪声抵消性能,结合被动降噪技术,很好地实现了在强噪声环境下消除噪声的目的.测试结果表明,该耳罩在低频范围内抗噪性能最高可达到30 dB.

  8. 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.

  9. 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.

  10. 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.

  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. 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.

  13. Could one single dichotomous noise cause resonant activation for exit time over potential barrier?

    Institute of Scientific and Technical Information of China (English)

    Li Jing-Hui

    2008-01-01

    This paper studies the mean first passage time (or exit time, or escape time) over the non-fluctuating potential barrier for a system driven only by a dichotomous noise. It finds that the dichotomous noise can make the particles escape over the potential barrier, in some circumstances; but in other circumstances, it can not. In the case that the particles escape over the potential barrier, a resonant activation phenomenon for the mean first passage time over the potential barrier is obtained.

  14. Efficiency in Controlling Activities

    OpenAIRE

    Van Nguyen, Tuyen

    2015-01-01

    Controlling is essential for financial success of corporations. An efficient controlling system should be implemented in order to manage financial performance from income, expense to profitability. The purpose of the thesis is to provide insight knowledge towards corporate accounting management as well as to propose potential improvement for the existing controlling system of the case company, which is Bosch Rexroth Japan. The theoretical framework creates the knowledge foundation for re...

  15. 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.

  16. 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.

  17. Dynamic Programming Principle for Stochastic Control Problems driven by General L\\'{e}vy Noise

    OpenAIRE

    Goldys, Ben; Wu, Wei

    2016-01-01

    We extend the proof of the dynamic programming principle (DPP) for standard stochastic optimal control problems driven by general L\\'{e}vy noises. Under appropriate assumptions, it is shown that the DPP still holds when the state process fails to have any moments at all.

  18. Cyclic pitch for the control of wind turbine noise amplitude modulation

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Aagaard Madsen, Helge; Fischer, Andreas;

    2014-01-01

    Using experimental data acquired during a wind turbine measurement campaign, it is shown that amplitude modulation of aerodynamic noise can be generated by the rotating blades in conjunction with the atmospheric wind shear. As an attempt to alleviate this phenomenon, a control strategy is designed...

  19. 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...

  20. 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...

  1. Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

    Science.gov (United States)

    Gaponenko, I.; Gamperle, L.; Herberg, K.; Muller, S. C.; Paruch, P.

    2016-06-01

    We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variation of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.

  2. The Coanda effect in gas-dynamic noise control. [pressure reduction by silencers

    Science.gov (United States)

    Vasilescu, G.

    1974-01-01

    The principle types of silencers are discussed for gas dynamic noise of free steam and gas expansions, as well as the results of research in gas dynamics of jets and applied acoustics. Gas dynamic noise attenuation by means of the Coanda effect is due to fluid decompression in a Coanda ejector of the external type, where a structural change takes place in the acoustic frequency spectrum and in its direction, as well as a substantial decrease in the fluid's velocity, temperature and concentration. This process is continued in the second phase with absorption of the acoustic waves by means of an active structure.

  3. 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

  4. An Ultra-High Stability, Low-Noise Laser Current Driver with Digital Control

    CERN Document Server

    Erickson, Christopher J; Doermann, Greg; Durfee, Dallin S

    2008-01-01

    We present a low-noise, high modulation-bandwidth design for a laser current driver with excellent long term stability. The driver improves upon the commonly-used Hall-Libbrecht design. The current driver can be operated remotely by way of a micro-processing unit, which controls the current set point digitally. This allows precise repeatability and improved accuracy and stability. It also allows the driver to be placed near the laser for reduced noise and for lower phase lag when using the modulation input. We present the theory of operation for our driver in detail, and give a thorough characterization of its stability, noise, set point accuracy and repeatability, temperature dependence, transient response, and modulation bandwidth.

  5. An ultrahigh stability, low-noise laser current driver with digital control

    Science.gov (United States)

    Erickson, Christopher J.; Van Zijll, Marshall; Doermann, Greg; Durfee, Dallin S.

    2008-07-01

    We present a low-noise, high modulation-bandwidth design for a laser current driver with excellent long-term stability. The driver improves upon the commonly used Hall-Libbrecht design. The current driver can be operated remotely by way of a microprocessing unit, which controls the current set point digitally. This allows precise repeatability and improved accuracy and stability. It also allows the driver to be placed near the laser for reduced noise and for lower phase lag when using the modulation input. We present the theory of operation for our driver in detail, and give a thorough characterization of its stability, noise, set-point accuracy and repeatability, temperature dependence, transient response, and modulation bandwidth.

  6. 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.

  7. 真空泵站的噪声控制%Noise Control of Vacuum Pumps Station

    Institute of Scientific and Technical Information of China (English)

    殷宝琴; 丁梅; 王敏; 郑文明; 杜红玲; 和海军

    2000-01-01

    The paper describes the overall scheme and design principle for noise control of a pumps station on basis of measuring and analyzing of the noise pollution of Roots Vacuum Pumps with two vanes.The constructions and the features of exhaust noise silencers of the vacuum pumps and other measures for reducing the noise of the pumps station are respectively presented.Application of the design to practical production and operation showed that obvious reduction of noise had been achieved.%在对两叶罗茨真空泵噪声测试分析的基础上,给出了泵站噪声控制的总体方案及设计原则,并对真空泵排气消声器及其它降噪措施的结构和特点分别进行了介绍。经实际应用及生产运行证明,降噪效果明显。

  8. Reduced In-Plane, Low Frequency Helicopter Noise of an Active Flap Rotor

    Science.gov (United States)

    Sim, Ben W.; Janakiram, Ram D.; Barbely, Natasha L.; Solis, Eduardo

    2009-01-01

    Results from a recent joint DARPA/Boeing/NASA/Army wind tunnel test demonstrated the ability to reduce in-plane, low frequency noise of the full-scale Boeing-SMART rotor using active flaps. Test data reported in this paper illustrated that acoustic energy in the first six blade-passing harmonics could be reduced by up to 6 decibels at a moderate airspeed, level flight condition corresponding to advance ratio of 0.30. Reduced noise levels were attributed to selective active flap schedules that modified in-plane blade airloads on the advancing side of the rotor, in a manner, which generated counteracting acoustic pulses that partially offset the negative pressure peaks associated with in-plane, steady thickness noise. These favorable reduced-noise operating states are a strong function of the active flap actuation amplitude, frequency and phase. The associated noise reductions resulted in reduced aural detection distance by up to 18%, but incurred significant vibratory load penalties due to increased hub shear forces. Small reductions in rotor lift-to-drag ratios, of no more than 3%, were also measured

  9. Hybrid feedforward-feedback active noise reduction for hearing protection and communication.

    Science.gov (United States)

    Ray, Laura R; Solbeck, Jason A; Streeter, Alexander D; Collier, Robert D

    2006-10-01

    A hybrid active noise reduction (ANR) architecture is presented and validated for a circumaural earcup and a communication earplug. The hybrid system combines source-independent feedback ANR with a Lyapunov-tuned leaky LMS filter (LyLMS) improving gain stability margins over feedforward ANR alone. In flat plate testing, the earcup demonstrates an overall C-weighted total noise reduction of 40 dB and 30-32 dB, respectively, for 50-800 Hz sum-of-tones noise and for aircraft or helicopter cockpit noise, improving low frequency (cancellation path gain. A fast time-domain identification method provides a high-fidelity, computationally efficient, infinite impulse response cancellation path model, which is used for both the filtered-X implementation and communication feedthrough. Insertion loss measurements made with a manikin show overall C-weighted total noise reduction provided by the ANR earplug of 46-48 dB for sum-of-tones 80-2000 Hz and 40-41 dB from 63 to 3000 Hz for UH-60 helicopter noise, with negligible degradation in attenuation during speech communication. For both hearing protectors, a stability metric improves by a factor of 2 to several orders of magnitude through hybrid ANR. PMID:17069300

  10. Bilateral use of active middle ear implants: speech discrimination results in noise.

    Science.gov (United States)

    Wolf-Magele, Astrid; Koci, Viktor; Schnabl, Johannes; Zorowka, Patrick; Riechelmann, Herbert; Sprinzl, Georg Mathias

    2016-08-01

    Binaural sound reception has advantages over unilateral perception, including better localization and sound quality as well as speech and tone reception in both quiet and noisy environments. Up to now, most active middle ear implant (AMEI) users have been unilaterally implanted, but patient demand for an implant on the other side is increasing. Ten bilaterally-AMEI implanted native German-speaking adults were included in the study. The Oldenburg sentence test was used to measure speech reception thresholds in noise. The subject's signal-to-noise ratio (SNR) at a speech reception score of 50 % was calculated for different noise conditions. SRT was measured as a function of noise condition (nc) and listening condition (lc)-for example, SRT (lc, nc), with nc from S0N0, S0N-90, or S0N90 and lc from left, right or both. For each noise condition, the squelch effect and the binaural summation effect were calculated. Patients in this study demonstrated improvement with bilateral AMEIs compared to right or left AMEI only in all three tested listening conditions. Statistical significance was found in the S0N0 condition to favor usage of bilateral AMI versus either the right or left side only. The benefits of binaural hearing are well known, also in normal-hearing individuals. In the future every bilateral implantation should be a part of the clinical routine. Bilateral implantation can help to reduce problems in background noise and restore directional hearing. PMID:26385811

  11. 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.

  12. 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...

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

    OpenAIRE

    Alagramam, Kumar N.; Ruben Stepanyan; Samson Jamesdaniel; Daniel H.-C. Chen; Rickie R Davis

    2014-01-01

    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 m...

  14. 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.

  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. 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.

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

    NARCIS (Netherlands)

    Ho, Jen-Hsuan; 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

  18. 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

  19. The Noise Pollution of Internal Engine and Its Control%车船用内燃发动机噪声污染及其控制

    Institute of Scientific and Technical Information of China (English)

    刘燕燕; 吴杰长; 郭文勇

    2000-01-01

    In order to meet theincreasing environmental demands, it's necessary to take measures to control noise produced by the internal engine. In this paper, the noise pollution sources of internal engine and theirs conventional control methods are analyzed. Based on the author' s study, the novel active noise control method developed with morden computer technology and cybernetics theory is introdhced.%分析了内燃机的噪声源和传统的无源降噪方法,结合作者的研究工作介绍了一种随计算机技术和现代控制理论发展起来的主动消声新技术-有源降噪。

  20. 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.

  1. Localized, Non-Harmonic Active Flap Motions for Low Frequency In-Plane Rotor Noise Reduction

    Science.gov (United States)

    Sim, Ben W.; Potsdam, Mark; Kitaplioglu, Cahit; LeMasurier, Philip; Lorber, Peter; Andrews, Joseph

    2012-01-01

    A first-of-its-kind demonstration of the use of localized, non-harmonic active flap motions, for suppressing low frequency, in-plane rotor noise, is reported in this paper. Operational feasibility is verified via testing of the full-scale AATD/Sikorsky/UTRC active flap demonstration rotor in the NFAC's 40- by 80-Foot anechoic wind tunnel. Effectiveness of using localized, non-harmonic active flap motions are compared to conventional four-per-rev harmonic flap motions, and also active flap motions derived from closed-loop acoustics implementations. All three approaches resulted in approximately the same noise reductions over an in-plane three-by-three microphone array installed forward and near in-plane of the rotor in the nearfield. It is also reported that using an active flap in this localized, non-harmonic manner, resulted in no more that 2% rotor performance penalty, but had the tendency to incur higher hub vibration levels.

  2. 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.

  3. General and efficient method for calculating modulation ressponses and noise spectra of active semiconductor waveguides

    DEFF Research Database (Denmark)

    Blaaberg, Søren; Öhman, Filip; Mørk, Jesper

    2008-01-01

    We present a theoretical method for obtaining small-signal responses in a spatially resolved active semiconductor waveguide including finite end-facet reflectivities and amplified spontaneous emission. RF-modulation responses and output noise spectra of an SOA are shown....

  4. 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

  5. Carbon Nanotube Thin Films for Active Noise Cancellation, Solar Energy Harvesting, and Energy Storage in Building Windows

    Science.gov (United States)

    Hu, Shan

    This research explores the application of carbon nanotube (CNT) films for active noise cancellation, solar energy harvesting and energy storage in building windows. The CNT-based components developed herein can be integrated into a solar-powered active noise control system for a building window. First, the use of a transparent acoustic transducer as both an invisible speaker for auxiliary audio playback and for active noise cancellation is accomplished in this work. Several challenges related to active noise cancellation in the window are addressed. These include secondary path estimation and directional cancellation of noise so as to preserve auxiliary audio and internal sounds while preventing transmission of external noise into the building. Solar energy can be harvested at a low rate of power over long durations while acoustic sound cancellation requires short durations of high power. A supercapacitor based energy storage system is therefore considered for the window. Using CNTs as electrode materials, two generations of flexible, thin, and fully solid-state supercapacitors are developed that can be integrated into the window frame. Both generations consist of carbon nanotube films coated on supporting substrates as electrodes and a solid-state polymer gel layer for the electrolyte. The first generation is a single-cell parallel-plate supercapacitor with a working voltage of 3 Volts. Its energy density is competitive with commercially available supercapacitors (which use liquid electrolyte). For many applications that will require higher working voltage, the second-generation multi-cell supercapacitor is developed. A six-cell device with a working voltage as high as 12 Volts is demonstrated here. Unlike the first generation's 3D structure, the second generation has a novel planar (2D) architecture, which makes it easy to integrate multiple cells into a thin and flexible supercapacitor. The multi-cell planar supercapacitor has energy density exceeding that of

  6. 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.

  7. 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.

  8. A Low Phase Noise CMOS Quadrature Voltage Control Oscillator Using Clock Gated Technique

    OpenAIRE

    Jothi Baskar A; Kalpana R

    2015-01-01

    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 ...

  9. 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...

  10. Noise-induced effects in an active medium with periodic boundary conditions

    Science.gov (United States)

    Slepnev, A. V.; Shepelev, I. A.; Vadivasova, T. E.

    2014-01-01

    A model of an active medium with periodic boundary conditions in which the elementary cell is represented by a FitzHugh-Nagumo oscillator has been studied. Depending on the system parameters, the elementary cell can occur in either auto-oscillatory or excitable state. In both cases, an autonomous medium in the absence of noise performs sustained oscillations and exhibits the phenomenon of multistability. A method for diagnostics of the character of medium with the aid of external noise is proposed, specific features in behavior of the system near the point of transition from the excitable to auto-oscillatory state are considered, and the phenomena of coherent resonance and noise-induced switching are described.

  11. A reconfigurable CBP/LP active RC filter with noise-shaping technique for wireless receivers

    International Nuclear Information System (INIS)

    A reconfigurable complex band-pass (CBP)/low-pass (LP) active-RC filter with a noise-shaping technique for wireless receivers is presented. Its bandwidth is reconfigurable among 500 kHz, 1 MHz and 4 MHz in LP mode and 1 MHz, 2 MHz and 8 MHz in CBP mode with 3 MHz center frequency. The Op-Amps used in the filter are realized in cell arrays in order to obtain scalable power consumption among the different operation modes. Furthermore, the filter can be configured into the 1st order, 2nd order or 3rd order mode, thus achieving a flexible filtering property. The noise-shaping technique is introduced to suppress the flicker noise contribution. The filter has been implemented in 180 nm CMOS and consumes less than 3 mA in the 3rd 8 MHz-bandwidth CBP mode. The spot noise at 100 Hz can be reduced by 14.4 dB at most with the introduced noise-shaping technique. (semiconductor integrated circuits)

  12. 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.

  13. 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.

  14. 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.

  15. Adaptive control of stochastic Hammerstein-Wiener nonlinear systems with measurement noise

    Science.gov (United States)

    Zhang, Bi; Mao, Zhizhong

    2016-01-01

    This paper deals with the adaptive control of a class of stochastic Hammerstein-Wiener nonlinear systems with measurement noise. Despite the fundamental progress achieved so far, a general theory framework about adaptive control of Hammerstein-Wiener models is still absent. Such situation is mainly due to the lack of an appropriate parameterisation model. To this end, this paper presents a novel parameterisation model that is to replace unmeasurable internal variables with their estimations. Then, the adaptive control algorithm to be applied is derived on the basis of self-tuning control. In addition, due to the use of the internal variable estimations, the stability and convergence properties are different from the self-tuning control. Our aim, in theoretical analysis, is to discover what limitations are in using the estimations instead of the true values in a control algorithm. Representative numerical examples are given and the simulation results verify the theoretical analysis.

  16. Aircraft noise effects on sleep: a systematic comparison of EEG awakenings and automatically detected cardiac activations

    International Nuclear Information System (INIS)

    Polysomnography is the gold standard for investigating noise effects on sleep, but data collection and analysis are sumptuous and expensive. We recently developed an algorithm for the automatic identification of cardiac activations associated with cortical arousals, which uses heart rate information derived from a single electrocardiogram (ECG) channel. We hypothesized that cardiac activations can be used as estimates for EEG awakenings. Polysomnographic EEG awakenings and automatically detected cardiac activations were systematically compared using laboratory data of 112 subjects (47 male, mean ± SD age 37.9 ± 13 years), 985 nights and 23 855 aircraft noise events (ANEs). The probability of automatically detected cardiac activations increased monotonically with increasing maximum sound pressure levels of ANEs, exceeding the probability of EEG awakenings by up to 18.1%. If spontaneous reactions were taken into account, exposure–response curves were practically identical for EEG awakenings and cardiac activations. Automatically detected cardiac activations may be used as estimates for EEG awakenings. More investigations are needed to further validate the ECG algorithm in the field and to investigate inter-individual differences in its ability to predict EEG awakenings. This inexpensive, objective and non-invasive method facilitates large-scale field studies on the effects of traffic noise on sleep

  17. Small-noise asymptotics of Hamilton-Jacobi-Bellman equations and bifurcations of stochastic optimal control problems

    NARCIS (Netherlands)

    D. Grass; T. Kiseleva; F. Wagener

    2015-01-01

    We derive small-noise approximations of the value function of stochastic optimal control problems over an unbounded domain and use these to perform a bifurcation analysis of these problems. The corresponding zero-noise problems may feature indifference (shock, Skiba) points, that is, points of non-d

  18. 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-threshol...

  19. 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.

  20. 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.

  1. Noise performance of frequency- and phase-locked CW magnetrons operated as current-controlled oscillators.

    OpenAIRE

    Tahir, I.; Dexter, A.; Carter, Richard G.

    2005-01-01

    Low-power continuous wave ``cooker'' magnetrons driven from industrial-quality switch-mode power supplies have been frequency locked by driving them as current-controlled oscillators in a phase-lock loop (PLL). The noise performance of these frequency-locked oscillators is reported as a function of heater power. The injection of -30- to -40-dB signals derived from the reference oscillator of the PLL into the magnetron's output waveguide while the anode current is controlled by the PLL is show...

  2. 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.

  3. 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.

  4. LETTER: Self-organized pattern formation and noise-induced control based on particle computations

    Science.gov (United States)

    Rohlf, Thimo; Bornholdt, Stefan

    2005-12-01

    We propose a new non-equilibrium model for spatial pattern formation based on local information transfer. Unlike most standard models of pattern formation it is not based on the Turing instability or initially laid down morphogen gradients. Information is transmitted through the system via particle-like excitations whose collective dynamics results in pattern formation and control. Here, a simple problem of domain formation is addressed by means of this model in an implementation as stochastic cellular automata, and then generalized to a system of coupled dynamical networks. One observes stable pattern formation, even in the presence of noise and cell flow. Noise contributes through the production of quasi-particles to de novo pattern formation as well as to robust control of the domain boundary position. Pattern proportions are scale independent as regards system size. The dynamics of pattern formation is stable over large parameter ranges, with a discontinuity at vanishing noise and a second-order phase transition at increased cell flow.

  5. Predicting the Inflow Distortion Tone Noise of the NASA Glenn Advanced Noise Control Fan with a Combined Quadrupole-Dipole Model

    Science.gov (United States)

    Koch, L. Danielle

    2012-01-01

    A combined quadrupole-dipole model of fan inflow distortion tone noise has been extended to calculate tone sound power levels generated by obstructions arranged in circumferentially asymmetric locations upstream of a rotor. Trends in calculated sound power level agreed well with measurements from tests conducted in 2007 in the NASA Glenn Advanced Noise Control Fan. Calculated values of sound power levels radiated upstream were demonstrated to be sensitive to the accuracy of the modeled wakes from the cylindrical rods that were placed upstream of the fan to distort the inflow. Results indicate a continued need to obtain accurate aerodynamic predictions and measurements at the fan inlet plane as engineers work towards developing fan inflow distortion tone noise prediction tools.

  6. Effectiveness of noise in blocking electromagnetic effects on enzyme activity in the chick embryo.

    Science.gov (United States)

    Martin, A H; Moses, G C

    1995-05-01

    We have previously demonstrated that exposure of the chick embryo to a 60 Hz, 4 microT split sine wave for the first 72 hours of development causes a significant reduction in the activity of the ectoenzyme 5'-nucleotidase. This reduced activity persisted, throughout the embryonic period, despite further incubation in a field free environment. We also showed that the reduction in 5'NT activity can be localized in the developing brain to the Cerebellum. The present study reveals that superimposition of an electromagnetic noise, of similar amplitude and frequency, can mitigate the effect of the field on 5'NT activity.

  7. 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.

  8. The Data Acquisition and Control Systems of the Jet Noise Laboratory at the NASA Langley Research Center

    Science.gov (United States)

    Jansen, B. J., Jr.

    1998-01-01

    The features of the data acquisition and control systems of the NASA Langley Research Center's Jet Noise Laboratory are presented. The Jet Noise Laboratory is a facility that simulates realistic mixed flow turbofan jet engine nozzle exhaust systems in simulated flight. The system is capable of acquiring data for a complete take-off assessment of noise and nozzle performance. This paper describes the development of an integrated system to control and measure the behavior of model jet nozzles featuring dual independent high pressure combusting air streams with wind tunnel flow. The acquisition and control system is capable of simultaneous measurement of forces, moments, static and dynamic model pressures and temperatures, and jet noise. The design concepts for the coordination of the control computers and multiple data acquisition computers and instruments are discussed. The control system design and implementation are explained, describing the features, equipment, and the experiences of using a primarily Personal Computer based system. Areas for future development are examined.

  9. Noise Response Data Reveal Novel Controllability Gramian for Nonlinear Network Dynamics

    Science.gov (United States)

    Kashima, Kenji

    2016-01-01

    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. PMID:27264780

  10. Optical control of antibacterial activity

    Science.gov (United States)

    Velema, Willem A.; van der Berg, Jan Pieter; Hansen, Mickel J.; Szymanski, Wiktor; Driessen, Arnold J. M.; Feringa, Ben L.

    2013-11-01

    Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment. Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desirable. Here we report a responsive, broad-spectrum, antibacterial agent that can be temporally activated with light, whereupon it auto-inactivates on the scale of hours. The use of such a ‘smart’ antibiotic might prevent the build-up of active antimicrobial material in the environment. Reversible optical control over active drug concentration enables us to obtain pharmacodynamic information. Precisely localized control of activity is achieved, allowing the growth of bacteria to be confined to defined patterns, which has potential for the development of treatments that avoid interference with the endogenous microbial population in other parts of the organism.

  11. 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.

  12. NOISE REGULATION

    OpenAIRE

    Cristina Voican; Constantin Stanescu

    2012-01-01

    Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After the watershed passage of the United States Noise Control Act of 1972, other local and state governments passed further regulations. Although the UK and Japan enacted national laws in 1960 and 1967 respectively, these laws were not at all comprehensive or fully enforceable as to address generally rising ambient noise, enforceable...

  13. 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

  14. ABOUT CONTROLLING OF SCIENTIFIC ACTIVITY

    Directory of Open Access Journals (Sweden)

    Mukhin V. V.

    2014-06-01

    Full Text Available We have selected the new area of controlling - scientific activity controlling. We consider some problems of development in this field, primarily the problem of selection of key performance indicators. It’s been founded that administrative measures stimulated the pursuit of a number of articles published in scientific journals hinders the development of science. Methodological errors - emphasis on citation indexes, impact factors, etc. - lead to wrong management decisions. As the experience of the UK, an expertise should be applied in the management of science. The article briefly discusses some of the drawbacks of the system of scientific specialties. It is proposed to expand research on the science of science and scientific activity controlling. We have also discussed the problems of controlling in applied research organizations

  15. 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.

  16. 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.

  17. Activation barrier scaling and crossover for noise-induced switching in a micromechanical parametric oscillator

    OpenAIRE

    Chan, H. B.; Stambaugh, C.

    2006-01-01

    We explore fluctuation-induced switching in a parametrically-driven micromechanical torsional oscillator. The oscillator possesses 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, w...

  18. Noise characterization of a pulse train generated by actively mode-locked lasers

    OpenAIRE

    Eliyahu, Danny; Salvatore, Randal A.; Yariv, Amnon

    1996-01-01

    We analyze the entire power spectrum of pulse trains generated by a continuously operating actively mode-locked laser in the presence of noise. We consider the effect of amplitude, pulse-shape, and timing-jitter fluctuations that are characterized by stationary processes. Effects of correlations between different parameters of these fluctuations are studied also. The nonstationary timing-jitter fluctuations of passively mode-locked lasers and their influence on the power spectrum is discussed...

  19. 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.

  20. Architecture for the real-time monitoring of noise pollution and marine mammal activity

    OpenAIRE

    Schaar, Mike van der; Zaugg, Serge Alain; Houegnigan, Ludwig; Castell Balaguer, Joan Vicent; André, Michel

    2010-01-01

    As acoustic pollution in the oceans is increasing, it is becoming more important to monitor it, with special attention on its effects on the behaviour of cetaceans. In the near future governments may require constant monitoring during sea construction projects or operations. One major construction activity in the coming years will be the construction of wind farms. Not only will these farms produce a constant low level noise in their direct environment while operating, but the ...

  1. Active control: Wind turbine model

    DEFF Research Database (Denmark)

    Bindner, H.

    1999-01-01

    validation as well as parameter estimation. The model includes a simple model of the structure of the turbine including tower and flapwise blade bending,a detailed model of the gear box and induction generator, a linearized aerodynamic model including modelling of induction lag and actuator and sensor models......This report is a part of the reporting of the work done in the project 'Active Control of Wind Turbines'. This project aim is to develop a simulation model for design of control systems for turbines with pitch control and to use that model to designcontrollers. This report describes the model...... developed for controller design and analysis. Emphasis has been put on establishment of simple models describing the dynamic behavior of the wind turbine in adequate details for controller design. This hasbeen done with extensive use of measurements as the basis for selection of model complexity and model...

  2. Electrical Maxwell demon and Szilard engine utilizing Johnson noise, measurement, logic and control.

    Science.gov (United States)

    Kish, Laszlo Bela; Granqvist, Claes-Göran

    2012-01-01

    We introduce a purely electrical version of Maxwell's demon which does not involve mechanically moving parts such as trapdoors, etc. It consists of a capacitor, resistors, amplifiers, logic circuitry and electronically controlled switches and uses thermal noise in resistors (Johnson noise) to pump heat. The only types of energy of importance in this demon are electrical energy and heat. We also demonstrate an entirely electrical version of Szilard's engine, i.e., an information-controlled device that can produce work by employing thermal fluctuations. The only moving part is a piston that executes work, and the engine has purely electronic controls and it is free of the major weakness of the original Szilard engine in not requiring removal and repositioning the piston at the end of the cycle. For both devices, the energy dissipation in the memory and other binary informatics components are insignificant compared to the exponentially large energy dissipation in the analog part responsible for creating new information by measurement and decision. This result contradicts the view that the energy dissipation in the memory during erasure is the most essential dissipation process in a demon. Nevertheless the dissipation in the memory and information processing parts is sufficient to secure the Second Law of Thermodynamics. PMID:23077525

  3. Dependence of regular background noise of VLF radiation and thunder-storm activity on solar wind proton density

    International Nuclear Information System (INIS)

    Correlation of the intensity of slowly changing regular background noise within 9.7 kHz frequency in Yakutsk (L = 3) and of the solar wind density protons was determined. This result explains the reverse dependence of the intensity of the regular background noise on the solar activity, 27-day frequency, increase before and following geomagnetic storms, absence of relation with Kp index of geomagnetic activity. Conclusion is made that growth of density of the solar wind protons results in increase of the regular background noise and thunderstorm activity

  4. Using noise to control heterogeneity of isogenic populations in homogenous environments

    Science.gov (United States)

    Szymańska, Paulina; Gritti, Nicola; Keegstra, Johannes M.; Soltani, Mohammad; Munsky, Brian

    2015-07-01

    We explore the extent to which the phenotypes of individual, genetically identical cells can be controlled independently from each other using only a single homogeneous environmental input. We show that such control is theoretically impossible if restricted to a deterministic setting, but it can be achieved readily if one exploits heterogeneities introduced at the single-cell level due to stochastic fluctuations in gene regulation. Using stochastic analyses of a bistable genetic toggle switch, we develop a control strategy that maximizes the chances that a chosen cell will express one phenotype, while the rest express another. The control mechanism uses UV radiation to enhance identically protein degradation in all cells. Control of individual cells is made possible only by monitoring stochastic protein fluctuations and applying UV control at favorable times and levels. For two identical cells, our stochastic control law can drive protein expression of a chosen cell above its neighbor with a better than 99% success rate. In a population of 30 identical cells, we can drive a given cell to remain consistently within the top 20%. Although cellular noise typically impairs predictability for biological responses, our results show that it can also simultaneously improve controllability for those same responses.

  5. Long-term transportation noise annoyance is associated with subsequent lower levels of physical activity.

    Science.gov (United States)

    Foraster, Maria; Eze, Ikenna C; Vienneau, Danielle; Brink, Mark; Cajochen, Christian; Caviezel, Seraina; Héritier, Harris; Schaffner, Emmanuel; Schindler, Christian; Wanner, Miriam; Wunderli, Jean-Marc; Röösli, Martin; Probst-Hensch, Nicole

    2016-05-01

    Noise annoyance (NA) might lead to behavioral patterns not captured by noise levels, which could reduce physical activity (PA) either directly or through impaired sleep and constitute a noise pathway towards cardiometabolic diseases. We investigated the association of long-term transportation NA and its main sources (aircraft, road, and railway) at home with PA levels. We assessed 3842 participants (aged 37-81) that attended the three examinations (SAP 1, 2, and 3 in years 1991, 2001 and 2011, respectively) of the population-based Swiss cohort on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA). Participants reported general 24-h transportation NA (in all examinations) and source-specific NA at night (only SAP 3) on an ICBEN-type 11-point scale. We assessed moderate, vigorous, and total PA from a short-questionnaire (SAP 3). The main outcome was moderate PA (active/inactive: cut-off≥150min/week). We used logistic regression including random effects by area and adjusting for age, sex, socioeconomic status, and lifestyles (main model) and evaluated potential effect modifiers. We analyzed associations with PA at SAP 3 a) cross-sectionally: for source-specific and transportation NA in the last year (SAP 3), and b) longitudinally: for 10-y transportation NA (mean of SAP 1+2), adjusting for prior PA (SAP 2) and changes in NA (SAP 3-2). Reported NA (score≥5) was 16.4%, 7.5%, 3%, and 1.1% for 1-year transportation, road, aircraft, and railway at SAP 3, respectively. NA was greater in the past, reaching 28.5% for 10-y transportation NA (SAP 1+2). The 10-y transportation NA was associated with a 3.2% (95% CI: 6%-0.2%) decrease in moderate PA per 1-NA rating point and was related to road and aircraft NA at night in cross-sectional analyses. The longitudinal association was stronger for women, reported daytime sleepiness or chronic diseases and it was not explained by objectively modeled levels of road traffic noise at SAP 3. In conclusion, long-term NA

  6. 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

  7. Reduction of current chopping noise with DSP controller in switched reluctance motor drive system

    Institute of Scientific and Technical Information of China (English)

    郭伟; 詹琼华; 马志源

    2002-01-01

    A novel current chopping mode was used in a switched reluctance motor drive system to make full use of the characteristics of digital signal processor (DSP) TMS320F240. The necessity of this 180° phase-shift current control (PSCC) mode is introduced first and then the principle of PSCC covering both hardware requirement and software programming is described in detail. The analysis made indicated that with this mode, the chopping frequency in winding can reach 20 kHz with 10 kHz power switches and the control frequency can reach 40 kHz at the same time. Subsequently, based on the linear and nonlinear mathematical models of the switched reluctance motor ( SRM), some simulation work has been done. The simulation results show that when this mode is applied to SRM drive (SRD) system, the current waveform becomes better. So the ripple of the torque is reduced simultaneously and the vibration and acoustic noise are reduced involuntarily. Stationary tests show that the acoustic noise is greatly diminished. Finally, some experiments were made using a 50 kW SRD system for electric vehicle (EV). Experimental results indicate that this mode can be implemented feasibly and it has a good action on the SRD system.

  8. Panels Manufactured from Vegetable Fibers: An Alternative Approach for Controlling Noises in Indoor Environments

    Directory of Open Access Journals (Sweden)

    Leopoldo Pacheco Bastos

    2012-01-01

    Full Text Available Noise control devices such as panels and barriers, when of high efficiency, generally are of difficult acquisition due to high costs turning in many cases their use impracticable, mainly for limited budget small-sized companies. There is a huge requirement for new acoustic materials that have satisfactory performance, not only under acoustic aspect but also other relevant ones and are of low cost. Vegetable fibers are an alternative solution when used as panels since they promise satisfactory acoustic absorption, according to previous researches, exist in abundance, and derive from renewable sources. This paper, therefore, reports on the development of panels made from vegetable fibers (coconut, palm, sisal, and açaí, assesses their applicability by various experimental (flammability, odor, fungal growth, and ageing tests, and characterize them acoustically in terms of their sound absorption coefficients on a scale model reverberant chamber. Acoustic results point out that the aforementioned fiber panels play pretty well the role of a noise control device since they have compatible, and in some cases, higher performance when compared to commercially available conventional materials.

  9. Open-loop control of noise amplification in a separated boundary layer flow

    CERN Document Server

    Boujo, Edouard; Gallaire, François

    2014-01-01

    Linear optimal gains are computed for the subcritical two-dimensional separated boundary-layer flow past a bump. Very large optimal gain values are found, making it possible for small-amplitude noise to be strongly amplified and to destabilize the flow. The optimal forcing is located close to the summit of the bump, while the optimal response is the largest in the shear layer. The largest amplification occurs at frequencies corresponding to eigenvalues which first become unstable at higher Reynolds number. Nonlinear direct numerical simulations show that a low level of noise is indeed sufficient to trigger random flow unsteadiness, characterized here by large-scale vortex shedding. Next, a variational technique is used to compute efficiently the sensitivity of optimal gains to steady control (through source of momentum in the flow, or blowing/suction at the wall). A systematic analysis at several frequencies identifies the bump summit as the most sensitive region for control with wall actuation. Based on thes...

  10. A flexible and high-performance bidirectional optical amplifier with all optical gain control using ASE noise path through multi-port circulators

    Institute of Scientific and Technical Information of China (English)

    An Vu Tran; Chang-Joon Chae; Rodney S. Tucker

    2003-01-01

    We report a flexible all-optical gain controlled bidirectional optical amplifier. The device achieves constant gain and low noise figure over a large input power range. Moreover, the device removes Rayleigh backscattered light and amplifier noise.

  11. A flexible and high-performance bidirectional optical amplifier with all-optical gain control using ASE noise path through multi-port circulators

    Institute of Scientific and Technical Information of China (English)

    An; Vu; Tran; Chang-Joon; Chae; Rodney; S.; Tucker

    2003-01-01

    We report a flexible all-optical gain controlled bidirectional optical amplifier. The device achieves constant gain and low noise figure over a large input power range. Moreover, the device removes Rayleigh backscattered light and amplifier noise.

  12. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  13. The Gain Stability and Output Signal-to-noise Ratio Analysis of the Negative Feedback Control in Genetic Circuits

    OpenAIRE

    Liu, S; Chen, C.

    2012-01-01

    Negative feedback genetic circuits (NFGC) are key regulatory motif of cellular robustness with the capability of reducing noise in genetic interaction network. NFGC have the same control theory frame as negative feedback amplifier circuits (NFAC). NFAC can enhance gain stability and output signal-to-noise ratio (OSNR) of output signal (voltage). Whether NFGC possess these two advantages or not is still unclear. We have investigated the advantages of NFGC through using feedback depth analysis ...

  14. Methods for addressing noise and error in controlled source electromagnetic data

    Science.gov (United States)

    MacLennan, Kristopher

    Controlled source electromagnetic geophysical surveys are excellent ways to obtain information about the conductivity structure of the earth, with applications including hydrocarbon and mining prospecting, hydrogeophysical detection and monitoring, and civil and archaeological studies. Invariably, however, various types of noise and errors obscure signal for desired targets, making interpretation difficult. In the case of time-lapse surveys, the magnitude of the measured difference is often on the order of the noise. Complex conductivity effects distort the measurements, leading to incorrect inversion results. This work develops a method for extracting signal from noisy electromagnetic data sets from both time- and frequency-domain surveys using a novel application of the equivalent source technique. It improves data contaminated by uncorrelated random noise, such as that due to receiver coil misalignment and location errors in time-domain EM surveys, and can remove static shifts in the observed electric field amplitude data due to near-surface geologic features in frequency-domain EM surveys. The equivalent source method can either be applied individually to data from each measured time-gate or frequency, or simultaneously to data from all times or frequencies measured. The method can be used in addition to traditional processing techniques and requires little user input. The effectiveness of the method is demonstrated through application to single-survey and time-lapsed noisy time- and frequency-domain EM data, both synthetically generated and collected in the field. The presence of low-frequency (≤ 1 kHz) polarization effects in earth porous materials noticeably increases the amplitude and decreases the phase of measured electromagnetic fields in frequency-domain surveys. By analyzing the sensitivity of cross-well EM measurements to the in-phase and quadrature conductivities, the contribution of the quadrature conductivity (directly associated with the low

  15. A Digital Controller for Active Aeroelastic Controls

    OpenAIRE

    Ueda, Tetsuhiko; MUROTA, Katsuichi; 上田, 哲彦; 室田, 勝一

    1989-01-01

    A high-speed digital controller for aeroelastic controls was designed and made. The purpose was to minimize adverse phase lag which is inevitably produced by the CPU time of digital processing. The delay deteriorates control performances on rather rapid phenomena like aircraft flutter. With fix-point operation the controller realized 417 microseconds of throughput time including the A/D and D/A conversion. This corresponds to a high sampling rate of 2.4kHz. The controller furnishes two channe...

  16. Active load control using microtabs

    Science.gov (United States)

    Yen, Dora Te-Lun

    2001-11-01

    Micro-electro-mechanical (MEM) translational tabs are introduced for enhancing and controlling the aerodynamic loading on lifting surfaces. These microtabs are mounted near the trailing edge of lifting surfaces, retract and extend approximately normal to the surface and have a maximum deployment height on the order of the boundary-layer thickness. Deployment of the device effectively modifies the camber distribution of the lifting surface and hence, the lift generated. The effect of the microtabs on lift is shown to be as powerful as conventional control surfaces with lift changes of 30%--50% in the linear range of the lift curve using a tab with a height of 1% of airfoil chord placed at 5% of chord upstream of the trailing edge on the lower surface. A multi-disciplinary approach incorporating aspects of experimental and computational aerodynamics, mechanical design and microfabrication techniques has been taken to develop and test a "proof of concept" model. Flow simulations, using a Reynolds-averaged Navier Stokes solver, have been conducted to optimize the size and placement of the devices based on trailing edge volume constraints. Numerical and experimental wind tunnel results are in good agreement, and both confirm that these micro-scale devices create macro-scale changes in aerodynamic loading. Application of this rather simple but innovative lift control system based on microfabrication techniques introduces a robust, dynamic control device and will allow for the miniaturization of conventional high lift and control systems. The result is a significant reduction in typical control system weight, complexity and cost. Also due to the minute size of these tabs, their activation and response times are much faster than that of conventional trailing edge devices. The "proof of concept" tab design, fabrication techniques, computational and experimental setup, and test results using a representative airfoil are presented in this research. (For more information, see

  17. Technology approach to aero engine noise reduction

    Energy Technology Data Exchange (ETDEWEB)

    Neise, W.; Enghardt, L. [Deutsches Zentrum fur Luft-und Raumfahrt -DLR, Institute of Propulsion Technology, Turbulence Research Div., Berlin (Germany)

    2003-07-01

    Transportation noise is one of the most pressing environmental problems of modern societies. Aircraft noise is second only to road traffic noise in drawing complaints from the public about noise pollution. Therefore intensive research efforts are necessary on the national levels as well as the European level to reduce the noise load around airports. The most effective and economical way to reach this goal is noise reduction at the source. The aero engines of today's transport aircraft are the dominant noise sources for most flight conditions, although air-frame noise does play an important role for landing aircraft. In this paper noise reduction studies for aero engines are described in which DLR are involved. The topics discussed are low noise fan design, active noise control using wall-flush loudspeakers as secondary sources, ANC using active stators as secondary sources, ANC using flow induced secondary sources at the rotor tips, reduction of low-pressure turbine noise, and flight tests for validation of add-on noise reduction devices. (authors)

  18. Activation process in excitable systems with multiple noise sources: Large number of units

    CERN Document Server

    Franović, Igor; Todorović, Kristina; Kostić, Srđan; Burić, Nikola

    2015-01-01

    We study the activation process in large assemblies of type II excitable units whose dynamics is influenced by two independent noise terms. The mean-field approach is applied to explicitly demonstrate that the assembly of excitable units can itself exhibit macroscopic excitable behavior. In order to facilitate the comparison between the excitable dynamics of a single unit and an assembly, we introduce three distinct formulations of the assembly activation event. Each formulation treats different aspects of the relevant phenomena, including the threshold-like behavior and the role of coherence of individual spikes. Statistical properties of the assembly activation process, such as the mean time-to-first pulse and the associated coefficient of variation, are found to be qualitatively analogous for all three formulations, as well as to resemble the results for a single unit. These analogies are shown to derive from the fact that global variables undergo a stochastic bifurcation from the stochastically stable fix...

  19. A low noise charge sensitive preamplifier with switch control feedback resistance

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper,the design and analysis of a new low noise charge sensitive preamplifier for silicon strip,Si(Li),CdZnTe and CsI detectors etc.with switch control feedback resistance were described,the entire system to be built using the CMOS transistors.The circuit configuration of the CSP proposed in this paper can be adopted to develop CMOS-based Application Specific Integrated Circuit further for Front End Electronics of read-out system of nuclear physits,particle physics and astrophysics research,etc.This work is an implemented design that we succeed after a simulation to obtain a rise time less than 3ns.the output resistance less than94Ω and the linearity almost good.

  20. Long-distance continuous-variable quantum key distribution by controlling excess noise

    Science.gov (United States)

    Huang, Duan; Huang, Peng; Lin, Dakai; Zeng, Guihua

    2016-01-01

    Quantum cryptography founded on the laws of physics could revolutionize the way in which communication information is protected. Significant progresses in long-distance quantum key distribution based on discrete variables have led to the secure quantum communication in real-world conditions being available. However, the alternative approach implemented with continuous variables has not yet reached the secure distance beyond 100 km. Here, we overcome the previous range limitation by controlling system excess noise and report such a long distance continuous-variable quantum key distribution experiment. Our result paves the road to the large-scale secure quantum communication with continuous variables and serves as a stepping stone in the quest for quantum network.

  1. Controllable single accumulated state-sequential acquisition with low signal noise ratio

    Institute of Scientific and Technical Information of China (English)

    JI Jiang; HUANG KaiZhi; JIN Liang; ZHANG LiZhi; ZHANG Meng

    2009-01-01

    The sequential estimation (SE) algorithm has a poor performance in the environment with a low signal-to-noise ratio (SNR) and a high bit error rate (BER), especially for unknown initial acquisition sequence. This paper summarizes the conventional sequence acquisition model, and discovers its several prob-persedly. To solve these problems, the paper presents a new algorithm, CSAS-SA (controllable single accumulated state-sequential acquisition). This algorithm accumulates the sequence innovation to a single appointed sequence state and makes the useful information accumulated effectively. Through simulation, CSAS-SA has a higher probability of success acquisition. When SNR equals -3 dB, the performance can be improved by 70%.

  2. Increasing LIGO sensitivity by feedforward subtraction of auxiliary length control noise

    CERN Document Server

    Meadors, Grant David; Riles, Keith

    2013-01-01

    LIGO, the Laser Interferometer Gravitational-wave Observatory, has been designed and constructed to measure gravitational wave strain via differential arm length. The LIGO 4-km Michelson arms with Fabry-Perot cavities have auxiliary length control servos for suppressing Michelson motion of the beam-splitter and arm cavity input mirrors, which degrades interferometer sensitivity. We demonstrate how a post-facto pipeline called AMPS improves a data sample from LIGO Science Run~6 with feedforward subtraction. Dividing data into 1024-second windows, AMPS numerically fits filter functions representing the frequency-domain transfer functions from Michelson length channels into the gravitational-wave strain data channel for each window, then subtracts the filtered Michelson channel noise (witness) from the strain channel (target). In this paper we describe the algorithm, assess achievable improvements in sensitivity to astrophysical sources, and consider relevance to future interferometry.

  3. Noise suppression by noise

    OpenAIRE

    Vilar, J. M. G.; Rubí Capaceti, José Miguel

    2001-01-01

    We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.

  4. Sensitivity and open-loop control of stochastic response in a noise amplifier flow: the backward-facing step

    CERN Document Server

    Boujo, Edouard

    2014-01-01

    The two-dimensional backward-facing step flow is a canonical example of noise amplifier flow: global linear stability analysis predicts that it is stable, but perturbations can undergo large amplification in space and time as a result of non-normal effects. This amplification potential is best captured by optimal transient growth analysis, optimal harmonic forcing, or the response to sustained noise. In view of reducing disturbance amplification in these globally stable open flows, a variational technique is proposed to evaluate the sensitivity of stochastic amplification to steady control. Existing sensitivity methods are extended in two ways to achieve a realistic representation of incoming noise: (i) perturbations are time-stochastic rather than time-harmonic, (ii) perturbations are localised at the inlet rather than distributed in space. This allows for the identification of regions where small-amplitude control is the most effective, without actually computing any controlled flows. In particular, passive...

  5. Does exposure to noise from human activities compromise sensory information from cephalopod statocysts?

    Science.gov (United States)

    Solé, Marta; Lenoir, Marc; Durfort, Mercè; López-Bejar, Manel; Lombarte, Antoni; van der Schaar, Mike; André, Michel

    2013-10-01

    Many anthropogenic noise sources are nowadays contributing to the general noise budget of the oceans. The extent to which sound in the sea impacts and affects marine life is a topic of considerable current interest both to the scientific community and to the general public. Cepaholopods potentially represent a group of species whose ecology may be influenced by artificial noise that would have a direct consequence on the functionality and sensitivity of their sensory organs, the statocysts. These are responsible for their equilibrium and movements in the water column. Controlled Exposure Experiments, including the use of a 50-400Hz sweep (RL=157±5dB re 1μPa with peak levels up to SPL=175dB re 1μPa) revealed lesions in the statocysts of four cephalopod species of the Mediterranean Sea, when exposed to low frequency sounds: (n=76) of Sepia officinalis, (n=4) Octopus vulgaris, (n=5) Loligo vulgaris and (n=2) Illex condietii. The analysis was performed through scanning (SEM) and transmission (TEM) electron microscopical techniques of the whole inner structure of the cephalopods' statocyst, especially on the macula and crista. All exposed individuals presented the same lesions and the same incremental effects over time, consistent with a massive acoustic trauma observed in other species that have been exposed to much higher intensities of sound: Immediately after exposure, the damage was observed in the macula statica princeps (msp) and in the crista sensory epithelium. Kinocilia on hair cells were either missing or were bent or flaccid. A number of hair cells showed protruding apical poles and ruptured lateral plasma membranes, most probably resulting from the extrusion of cytoplasmic material. Hair cells were also partially ejected from the sensory epithelium, and spherical holes corresponding to missing hair cells were visible in the epithelium. The cytoplasmic content of the damaged hair cells showed obvious changes, including the presence of numerous vacuoles

  6. Spectral characterisation and noise performance of Vanilla—an active pixel sensor

    Science.gov (United States)

    Blue, Andrew; Bates, R.; Bohndiek, S. E.; Clark, A.; Arvanitis, Costas D.; Greenshaw, T.; Laing, A.; Maneuski, D.; Turchetta, R.; O'Shea, V.

    2008-06-01

    This work will report on the characterisation of a new active pixel sensor, Vanilla. The Vanilla comprises of 512×512 (25μm 2) pixels. The sensor has a 12 bit digital output for full-frame mode, although it can also be readout in analogue mode, whereby it can also be read in a fully programmable region-of-interest (ROI) mode. In full frame, the sensor can operate at a readout rate of more than 100 frames per second (fps), while in ROI mode, the speed depends on the size, shape and number of ROIs. For example, an ROI of 6×6 pixels can be read at 20,000 fps in analogue mode. Using photon transfer curve (PTC) measurements allowed for the calculation of the read noise, shot noise, full-well capacity and camera gain constant of the sensor. Spectral response measurements detailed the quantum efficiency (QE) of the detector through the UV and visible region. Analysis of the ROI readout mode was also performed. Such measurements suggest that the Vanilla APS (active pixel sensor) will be suitable for a wide range of applications including particle physics and medical imaging.

  7. Contralateral parahippocampal gamma-band activity determines noise-like tinnitus laterality: a region of interest analysis.

    Science.gov (United States)

    Vanneste, S; Heyning, P Van de; Ridder, D De

    2011-12-29

    Tinnitus is described as an auditory perception in the absence of any external sound source. Tinnitus loudness has been correlated to sustained high frequency gamma-band activity in auditory cortex. It remains unknown whether unilateral tinnitus is always generated in the left auditory cortex, irrespective of the side on which the tinnitus is perceived, or in the contralateral auditory cortex. In order to solve this enigma source localized electroencephalographic (EEG) recordings of a homogenous group of unilateral left and right-sided tinnitus patients presenting with noise-like tinnitus was analyzed. Based on a region of interest analysis, the most important result of this study is that tinnitus lateralization depended on the gamma-band activity of the contralateral parahippocampal area. As for the auditory cortex no differences were found between left-sided and right-sided tinnitus patients. However, in comparison to a control group both left and right-sided tinnitus patients had an increased gamma-band activity in both the left and right primary and secondary auditory cortex. Thus whereas in tinnitus the primary and secondary auditory cortices of both sides are characterized by increased gamma-band activity, the side on which the tinnitus is perceived relates to gamma-band activity in the contralateral parahippocampal area. PMID:21920411

  8. 风电冷却系统噪声控制%Noise Control of Windmill Cooling System

    Institute of Scientific and Technical Information of China (English)

    彭若龙; 夏博雯; 谢凌志; 林胜

    2013-01-01

    针对国内某风电机组冷却系统噪声扰民问题,进行噪声控制。通过振动噪声测试分析确定主要声源,研究设计相应的减隔振方案、消声器声屏障降噪方案以及塔桶内部吸声降噪等方案和相应的减振降噪器件,并开展整体噪声控制方案的实施和评价。最终关键点噪声降低达到22 dB,有效解决了噪声扰民问题,并有效提升该机型海外市场的竞争力。%The noise control of a typical windmill turbine cooling system was studied, including the measurement of noise sources, design of noise control strategy, effects of sound barrier and silencer, materials and devices for sound absorption and reduction etc. The global noise control strategy was implemented and evaluated. As a consequence, the sound level in the key position of the system was reduced to 22 dB, and the noise problem was solved, which can effectively improve the windmill competitiveness in the overseas markets.

  9. Nonlinear Stochastic H∞ Control with Markov Jumps and (x,u,v-Dependent Noise: Finite and Infinite Horizon Cases

    Directory of Open Access Journals (Sweden)

    Li Sheng

    2014-01-01

    Full Text Available This paper is concerned with the H∞ control problem for nonlinear stochastic Markov jump systems with state, control, and external disturbance-dependent noise. By means of inequality techniques and coupled Hamilton-Jacobi inequalities, both finite and infinite horizon H∞ control designs of such systems are developed. Two numerical examples are provided to illustrate the effectiveness of the proposed design method.

  10. Effects of solar activity and geomagnetic field on noise in CALIOP profiles above the South Atlantic Anomaly

    Directory of Open Access Journals (Sweden)

    V. Noel

    2013-09-01

    Full Text Available By documenting noise levels in 6.5 yr of nighttime measurements by the spaceborne lidar CALIOP above the South Atlantic Anomaly (SAA, we show they contain information about the evolution of upwelling high-energy radiation levels in the area. We find the amount of noisy profiles is influenced by the 11 yr cycle of solar activity, fluctuates by ±5% between 2006 and 2013, and is anticorrelated with solar activity with a 1 yr lag. The size of the SAA grows as solar activity decreases, and an overall westward shift of the SAA region is detectable. We predict SAA noise levels will increase anew after 2014, and will affect future spaceborne lidar missions most near 2020. In other areas, supposedly unaffected by incoming sunlight, nighttime noise levels are much weaker but follow the same 11 yr cycle, superimposed with a one-year cycle that affects both hemispheres similarly and could be attributed to geomagnetic activity.

  11. Comparison of Gap in Noise Test Results in Musicians and Non-Musician Controls

    Directory of Open Access Journals (Sweden)

    Ghassem Mohamadkhani

    2011-12-01

    Full Text Available 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 hearing non-musician controls with mean age of 24.5 years, in Faculty of Rehabilitation of Tehran University of Medical Sciences. GIN test results (approximate threshold and percent of corrected answers obtained and analyzed by Mann-Whitney non-parametric statistical test.Results: There was significant difference between approximate threshold and percent of corrected answers between musicians and non-musician group (p0.05.Conclusion: the lower approximate threshold and the more corrected answers in GIN test by musician group indicate rapid auditory temporal processing ability of this group rather than non-musicians group. This might be related to effects of musical training on central auditory processing.

  12. Adaptive Helmholtz resonators and passive vibration absorbers for cylinder interior noise control

    Science.gov (United States)

    Estève, Simon J.; Johnson, Marty E.

    2005-12-01

    This paper presents an adaptive-passive solution to control the broadband sound transmission into rocket payload fairings. The treatment is composed of passive distributed vibration absorbers (DVAs) and adaptive Helmholtz resonators (HR). Both the frequency domain and time-domain model of a simply supported cylinder excited by an external plane wave are developed. To tune vibration absorbers to tonal excitation, a tuning strategy, based on the phase information between the velocity of the absorber mass and the velocity of the host structure is used here in a new fashion to tune resonators to peaks in the broadband acoustic spectrum of a cavity. This tuning law, called the dot-product method, only uses two microphone signals local to each HR, which allows the adaptive Helmholtz resonator (AHR) to be manufactured as an autonomous device with power supply, sensor, actuator and controller integrated. Numerical simulations corresponding to a 2.8 m long 2.5 m diameter composite cylinder prototype demonstrate that, as long as the structure modes, which strongly couple to the acoustic cavity, are damped with a DVA treatment, the dot-product method tune multiple HRs to a near-optimal solution over a broad frequency range (40-160 Hz). An adaptive HR prototype with variable opening is built and characterized. Experiments conducted on the cylinder prototype with eight AHRs demonstrate the ability of resonators adapted with the dot-product method to converge to near-optimal noise attenuation in a frequency band including multiple resonances.

  13. Anti-noise Technique of Control System%控制系统的抗噪声技术

    Institute of Scientific and Technical Information of China (English)

    罗耀东; 徐义亨

    2001-01-01

    The anti-noise technique in industrial process control system is introduced.The reasons caused noise such as electric coupling,magnetic coupling,electric-magnetic noise and resistance coupling are presented.The anti-noise technique such as cable selection, grounding,digital filter and watchdog are presented too.If the anti-noise problems are solved properly,it will be significant help for debugging and running of control system.%叙述工业过程控制系统的抗噪声技术;阐述形成噪声的原因,包括电容性耦合、电感性耦合、电磁辐射耦合和公共阻抗耦合;还阐述了抑制噪声的各种方法,包括噪声源的抑制、电缆的选型、接地、数字滤波和看门狗技术。正确地解决噪声问题,将大大有助于控制系统的调整和运行。

  14. A Real-time Auto-detection Method for Random Telegraph Signal (RTS) Noise Detection in CMOS Active pixel sensors

    International Nuclear Information System (INIS)

    CMOS Active pixel sensors (CMOS APS) are attractive for use in the innermost layers of charged particle trackers, due to their good tradeoffs among the key performances. However, CMOS APS can be greatly influenced by random telegraph signal (RTS) noise, which can cause particle tracking or energy calculation failures. In-depth research of pixels' RTS behavior stimulates the interest of the methods for RTS noise detection, reconstruction and parameters extraction. In this paper, a real-time auto-detection method is proposed, using real-time Gaussian noise standard deviation as the detection threshold. Experimental results show that, compared with current methods using signal standard deviation as the thresholds, the proposed method is more sensitive in multi-level RTS detection and more effective in the case of RTS noise degradation

  15. Active inference and robot control: a case study

    Science.gov (United States)

    Nizard, Ange; Friston, Karl; Pezzulo, Giovanni

    2016-01-01

    Active inference is a general framework for perception and action that is gaining prominence in computational and systems neuroscience but is less known outside these fields. Here, we discuss a proof-of-principle implementation of the active inference scheme for the control or the 7-DoF arm of a (simulated) PR2 robot. By manipulating visual and proprioceptive noise levels, we show under which conditions robot control under the active inference scheme is accurate. Besides accurate control, our analysis of the internal system dynamics (e.g. the dynamics of the hidden states that are inferred during the inference) sheds light on key aspects of the framework such as the quintessentially multimodal nature of control and the differential roles of proprioception and vision. In the discussion, we consider the potential importance of being able to implement active inference in robots. In particular, we briefly review the opportunities for modelling psychophysiological phenomena such as sensory attenuation and related failures of gain control, of the sort seen in Parkinson's disease. We also consider the fundamental difference between active inference and optimal control formulations, showing that in the former the heavy lifting shifts from solving a dynamical inverse problem to creating deep forward or generative models with dynamics, whose attracting sets prescribe desired behaviours. PMID:27683002

  16. Development of a Pseudo-Uniform Structural Quantity for the Active Control of Structural Radiation

    OpenAIRE

    Fisher, Jeffrey; Blotter, Jon

    2010-01-01

    Active noise control has been a highly researched field over the past few decades but the active control of the radiating structures has recently excited interest. Multiple structural quantities and their relationships to acoustic radiation are investigated. This paper also looks at the control of a new structural quantity developed taking advantage of the principle of Rayleigh’s integral and radiated power being strongly dependent on volume velocity. The benefit of this new quantity is that ...

  17. An alternative method for noise analysis using pixel variance as part of quality control procedures on digital mammography systems.

    NARCIS (Netherlands)

    Bouwman, R.; Young, K.; Lazzari, B.; Ravaglia, V.; Broeders, M.J.M.; Engen, R. van

    2009-01-01

    According to the European Guidelines for quality assured breast cancer screening and diagnosis, noise analysis is one of the measurements that needs to be performed as part of quality control procedures on digital mammography systems. However, the method recommended in the European Guidelines does n

  18. Numerical Investigation of Jet Noise Prediction in Exhaust Nozzle by Passive Control Techniques

    Directory of Open Access Journals (Sweden)

    Alagu sundaram.A

    2015-05-01

    Full Text Available The project mainly focuses on the reduction of jet noise emission in the exhaust nozzle of TURBOFAN ENGINES. Reduction of noise in the exhaust system is done by attaching chevrons with particular parameters in the nozzle exit. Numerical investigations have been carried out on chevron nozzles to assess the importance of chevron parameters such as the number of chevrons like (chevron count, chevron penetration and the mixing characteristics of co flow jet. Chevron count is the pertinent parameter for noise reduction at low nozzle pressure ratios, whereas at high nozzle pressure ratios, chevron penetration is crucial. The results illustrate that by careful selection of chevron parameters substantial noise reduction can be achieved. The sound pressure level (SPL can be calculated from that we determined the noise level at nozzle exit section. After assessing the chevron parameters we are going to modify the chevron shapes in order to get maximum noise reduction along with very negligible thrust loss. Modification of chevron is based on aspect of increasing the mixing of cold jet and the hot jet in order to decrease the noise emission. ANSYS-Fluent is a commercial CFD code which will be used for performing the simulation and the simulation configuration contains three different velocities (100,150,200 with two different nozzle model(plain & chevron nozzle. The simulation results are evaluated to find out nozzle noise level in the engine exhaust system.

  19. Experimental Investigations of Noise Control in Planetary Gear Set by Phasing

    Directory of Open Access Journals (Sweden)

    S. H. Gawande

    2014-01-01

    Full Text Available Now a days reduction of gear noise and resulting vibrations has received much attention of the researchers. The internal excitation caused by the variation in tooth mesh stiffness is a key factor in causing vibration. Therefore to reduce gear noise and vibrations several techniques have been proposed in recent years. In this research the experimental work is carried out to study the effect of planet phasing on noise and subsequent resulting vibrations of Nylon-6 planetary gear drive. For this purpose experimental set-up was built and trials were conducted for two different arrangements (i.e., with phasing and without phasing and it is observed that the noise level and resulting vibrations were reduced by planet phasing arrangement. So from the experimental results it is observed that by applying the meshing phase difference one can reduce planetary gear set noise and vibrations.

  20. Active Vibration Control of the Smart Plate Using Artificial Neural Network Controller

    Directory of Open Access Journals (Sweden)

    Mohit

    2015-01-01

    Full Text Available The active vibration control (AVC of a rectangular plate with single input and single output approach is investigated using artificial neural network. The cantilever plate of finite length, breadth, and thickness having piezoelectric patches as sensors/actuators fixed at the upper and lower surface of the metal plate is considered for examination. The finite element model of the cantilever plate is utilized to formulate the whole strategy. The compact RIO and MATLAB simulation software are exercised to get the appropriate results. The cantilever plate is subjected to impulse input and uniform white noise disturbance. The neural network is trained offline and tuned with LQR controller. The various training algorithms to tune the neural network are exercised. The best efficient algorithm is finally considered to tune the neural network controller designed for active vibration control of the smart plate.

  1. 数控冲床噪声控制研究%Noise Research on Numerical Control Punch

    Institute of Scientific and Technical Information of China (English)

    许颖颖

    2012-01-01

    Numerical control punch inevitably makes a noise in the work by vibration of working components. It not only interferes with working environment and affects working efficiency and qualiyt but also it harms to human health. This paper obtains the main source of the noise by field tests and adopts measures to reduce the noise.%数控冲床在运行过程中不可避免会产生由振动以及其零部件工作时引起的噪声,干扰工作环境,影响工作效率,降低工作品质,甚至危害人体健康.论文通过对数控冲床的现场噪声测试,分析了噪声的主要来源,并采用了相应的措施,取得了一定的降噪效果.

  2. Temperature Control and Noise Reduction in our Compact ADR System for TES Microcalorimeter Operation

    Science.gov (United States)

    Hishi, U.; Fujimoto, R.; Kamiya, K.; Kotake, M.; Ito, H.; Kaido, T.; Tanaka, K.; Hattori, K.

    2016-08-01

    We have been developing a compact adiabatic demagnetization refrigerator, keeping ground application and future missions in mind. A salt pill fabricated in-house, a superconducting magnet with a passive magnetic shield around it, and a mechanical heat switch are mounted in a dedicated helium cryostat. The detector stage temperature is regulated by PID control of the magnet current, with a dI/dt term added to compensate the temperature rise due to parasitic heat. The temperature fluctuation of the detector stage is 1-2 \\upmu Krms, and the hold time was extended by about 15 % thanks to the dI/dt term. Bundle shields of the harnesses between the cryostat and the analog electronics boxes were connected to the chassis at both ends, and the analog electronics boxes were grounded to the cryostat through the bundle shields. This reduced the readout noise to 16 pA/√{Hz} in the 10-60 kHz range. Using this system, an energy resolution of 3.8 ± 0.2 eV (FWHM) was achieved at 5.9 keV.

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

    Science.gov (United States)

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

    1980-01-01

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

  4. A controllable noise-like operation regime in a Yb-doped dispersion-mapped fiber ring laser

    Science.gov (United States)

    Zaytsev, A. K.; Lin, C. H.; You, Y. J.; Tsai, F. H.; Wang, C. L.; Pan, C. L.

    2013-04-01

    We report the generation of tunable high-energy noise-like pulses with a super-broadband spectrum from a Yb-doped dispersion-mapped fiber ring laser. Self-starting noise-like operation can be maintained over a relatively large range of pumping powers (4-13 W). The corresponding output power varies from 0.1 to 1.45 W. The maximum 3 dB spectral bandwidth of the noise-like pulses is about 48.2 nm while the output energy is as high as 47 nJ, limited by optical damage of the components. The central wavelength of the noise-like pulses can be tuned easily over ˜12 nm. The bandwidth and duration of the generated wave packets can also be controlled. The use of a negative dispersion-delay line and spectral filter are found to be important for generating such high-power noise-like operation. Experimental results are in good agreement with theoretical simulations.

  5. Effects of scanner acoustic noise on intrinsic brain activity during auditory stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Yakunina, Natalia [Kangwon National University, Institute of Medical Science, School of Medicine, Chuncheon (Korea, Republic of); Kangwon National University Hospital, Neuroscience Research Institute, Chuncheon (Korea, Republic of); Kang, Eun Kyoung [Kangwon National University Hospital, Department of Rehabilitation Medicine, Chuncheon (Korea, Republic of); Kim, Tae Su [Kangwon National University Hospital, Department of Otolaryngology, Chuncheon (Korea, Republic of); Kangwon National University, School of Medicine, Department of Otolaryngology, Chuncheon (Korea, Republic of); Min, Ji-Hoon [University of Michigan, Department of Biopsychology, Cognition, and Neuroscience, Ann Arbor, MI (United States); Kim, Sam Soo [Kangwon National University Hospital, Neuroscience Research Institute, Chuncheon (Korea, Republic of); Kangwon National University, School of Medicine, Department of Radiology, Chuncheon (Korea, Republic of); Nam, Eui-Cheol [Kangwon National University Hospital, Neuroscience Research Institute, Chuncheon (Korea, Republic of); Kangwon National University, School of Medicine, Department of Otolaryngology, Chuncheon (Korea, Republic of)

    2015-10-15

    Although the effects of scanner background noise (SBN) during functional magnetic resonance imaging (fMRI) have been extensively investigated for the brain regions involved in auditory processing, its impact on other types of intrinsic brain activity has largely been neglected. The present study evaluated the influence of SBN on a number of intrinsic connectivity networks (ICNs) during auditory stimulation by comparing the results obtained using sparse temporal acquisition (STA) with those using continuous acquisition (CA). Fourteen healthy subjects were presented with classical music pieces in a block paradigm during two sessions of STA and CA. A volume-matched CA dataset (CAm) was generated by subsampling the CA dataset to temporally match it with the STA data. Independent component analysis was performed on the concatenated STA-CAm datasets, and voxel data, time courses, power spectra, and functional connectivity were compared. The ICA revealed 19 ICNs; the auditory, default mode, salience, and frontoparietal networks showed greater activity in the STA. The spectral peaks in 17 networks corresponded to the stimulation cycles in the STA, while only five networks displayed this correspondence in the CA. The dorsal default mode and salience networks exhibited stronger correlations with the stimulus waveform in the STA. SBN appeared to influence not only the areas of auditory response but also the majority of other ICNs, including attention and sensory networks. Therefore, SBN should be regarded as a serious nuisance factor during fMRI studies investigating intrinsic brain activity under external stimulation or task loads. (orig.)

  6. Resistive wall mode active control physics design for KSTAR

    Science.gov (United States)

    Park, Y. S.; Sabbagh, S. A.; Bak, J. G.; Bialek, J. M.; Berkery, J. W.; Lee, S. G.; Oh, Y. K.

    2014-01-01

    As KSTAR H-mode operation approaches the region where the resistive wall mode (RWM) can be unstable, an important issue for future long pulse, high beta plasma operation is to evaluate RWM active feedback control performance using a planned active/passive RWM stabilization system on the device. In particular, an optimal design of feedback sensors allows mode stabilization up to the highest achievable βN close to the ideal with-wall limit, βNwall, with reduced control power requirements. The computed ideal n = 1 mode structure from the DCON code has been input to the VALEN-3D code to calculate the projected performance of an active RWM control system in the KSTAR three-dimensional conducting structure device geometry. Control performance with the midplane locked mode detection sensors, off-midplane saddle loops, and magnetic pickup coils is examined. The midplane sensors measuring the radial component of the mode perturbation is found to be strongly affected by the wall eddy current. The off-axis saddle loops with proper compensation of the prompt applied field are computed to provide stabilization at βN up to 86% of βNwall but the low RWM amplitude computed in the off-axis regions near the sensors can produce a low signal-to-noise ratio. The required control power and bandwidth are also estimated with varied noise levels in the feedback sensors. Further improvements have been explored by examining a new RWM sensor design motivated by the off-midplane poloidal magnetic field sensors in NSTX. The new sensors mounted off of the copper passive stabilizer plates near the device midplane show a clear advantage in control performance corresponding to achieving 99% of βNwall without the need of compensation of the prompt field. The result shows a significant improvement of RWM feedback stabilization using the new sensor set which motivates a future feedback sensor upgrade.

  7. Optimizing Noise Attenuation in Aircraft Exhaust Ducts Employing Passive and Active Absorbing Splitters and Struts Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA requires accurate numerical simulation of high bypass nacelle acoustics and the development of advanced nacelle absorption techniques to reduce engine noise...

  8. STUDY ON NOISE LEVEL GENERATED BY HUMAN ACTIVITIES IN SIBIU CITY, ROMANIA

    Directory of Open Access Journals (Sweden)

    Cristina STANCA-MOISE

    2014-10-01

    Full Text Available In this paper I have proposed an analysis and monitoring of the noise sources in the open spaces of air traffic, rail and car in Sibiu. From centralizing data obtained from the analysis of the measurements performed with equipment noise levels, we concluded that the noise and vibration produced by means of Transportation (air, road, rail can affect human health if they exceed limits. Noise is present and part of our lives and always a source of pollution as any of modern man is not conscious.

  9. Active interaction control for civil structures

    OpenAIRE

    Wang, Luo-Jia

    1997-01-01

    This thesis presents a civil engineering approach to active control for civil structures. The proposed control technique, termed Active Interaction Control (AIC), utilizes dynamic interactions between different structures, or components of the same structure, to reduce the resonance response of the controlled or primary structure under earthquake excitations. The primary control objective of AIC is to minimize the maximum story drift of the primary structure. This is accomplished by timing th...

  10. METHODS OF PROVIDING NOISE IMMUNITY IN AUTOMOBILE ANTI-THEFT SYSTEM CONTROL

    OpenAIRE

    Frolov, V.; Kovtunov, J.; Kubata, V.

    2013-01-01

    In modern ani-theft systems they use frequency and phase modulation. Since the width of the signal is limited, it is possible to intercept the signal and then switch off the alarm at the right time.To ensure the noise immunity and secrecy manufacturers use more sophisticated codes using the methods of cryptography. Significant increase in noise immunity in modern ani-theft systems is possible using broadband signals.

  11. Cooperative Control Method of Active and Semiactive Control: New Framework for Vibration Control

    OpenAIRE

    Kazuhiko Hiramoto

    2014-01-01

    A new control design framework for vibration control, the cooperative control of active and semiactive control, is proposed in the paper. In the cooperative control, a structural system having both of an actuator and a semiactive control device, for example, MR damper and so forth, is defined as the control object. In the proposed control approach, the higher control performance is aimed by the cooperative control between the active control with the actuator and the semiactive control with th...

  12. A model for signal processing and predictive control of semi-active structural control system

    Indian Academy of Sciences (India)

    M-H Shih; W-P Sung; Ching-Jong Wang

    2009-06-01

    The theory for structural control has been well developed and applied to perform excellent energy dissipation using dampers. Both active and semi-active control systems may be used to decide on the optimal switch point of the damper based on the current and past structural responses to the excitation of external forces. However, numerous noises may occur when the control signals are accessed and transported thus causing a delay of the damper. Therefore, a predictive control technique that integrates an improved method of detecting the control signal based on the direction of the structural motion, and a calculator for detecting the velocity using the least-square polynomial regression is proposed in this research. Comparisons of the analytical data and experimental results show that this predictor is effective in switching the moving direction of the semi-active damper. This conclusion is further verified using the component and shaking table test with constant amplitude but various frequencies, and the El Centro earthquake test. All tests confirm that this predictive control technique is effective to alleviate the time delay problem of semi-active dampers. This predictive control technique promotes about 30% to 40% reduction of the structural displacement response and about 35% to 45% reduction of the structural acceleration response.

  13. Curve Squeal of Train Wheels, Part 3: Active Control

    Science.gov (United States)

    HECKL, MARIA A.; HUANG, X. Y.

    2000-01-01

    This paper presents a new method to annul the squeal noise that is produced by trains traversing a curve. The method is a special form of active control, applied to suppress the bending oscillations of a squealing wheel. It is essentially a feedback system with the following components: sensor, narrowband filter, phase-shifter, amplifier and actuator. The control signal driving the actuator has only a single frequency (set at the filter), and that frequency typically corresponds to one of the bending modes of the wheel. Two versions of the feedback system are considered. In the first version, the actuator exerts a control force on the wheel, and in the second version, the actuator imposes a velocity on the rail. A mathematical model is presented and predictions are made for the performance of both versions. The coupling of the different wheel modes by the control system is discussed. A model rig is described which was used for a practical demonstration of this form of active control. Differences from more conventional forms of active control are pointed out.

  14. Microglial control of neuronal activity

    Directory of Open Access Journals (Sweden)

    Catherine eBéchade

    2013-03-01

    Full Text Available Fine-tuning of neuronal activity was thought to be a neuron-autonomous mechanism until the discovery that astrocytes are active players of synaptic transmission. The involvement of astrocytes has changed our understanding of the roles of non-neuronal cells and shed new light on the regulation of neuronal activity. Microglial cells are the macrophages of the brain and they have been mostly investigated as immune cells. However recent data discussed in this review support the notion that, similarly to astrocytes, microglia are involved in the regulation of neuronal activity. For instance, in most, if not all, brain pathologies a strong temporal correlation has long been known to exist between the pathological activation of microglia and dysfunction of neuronal activity. Recent studies have convincingly shown that alteration of microglial function is responsible for pathological neuronal activity. This causal relationship has also been demonstrated in mice bearing loss-of-function mutations in genes specifically expressed by microglia. In addition to these long-term regulations of neuronal activity, recent data show that microglia can also rapidly regulate neuronal activity, thereby acting as partners of neurotransmission.

  15. Dynamics and Synchronization of Noise Perturbed Ensembles of Periodically Activated neuron Cells

    DEFF Research Database (Denmark)

    Belykh, V. N.; Pankratova, Evgeniya; Mosekilde, Erik

    2008-01-01

    The role of noise for a single neuron and for an ensemble of mutually coupled neurons is investigated. For a single element we show that an increase in noise intensity in the regime of irregular. ring enhances the coherence of the neuronal response. For this regime of spiking a study...

  16. Flow and Noise Control in High Speed and High Reynolds Number Jets Using Plasma Actuators

    Science.gov (United States)

    Samimy, M.; Kastner, J.; Kim, J.-H.; Utkin, Y.; Adamovich, I.; Brown, C. A.

    2006-01-01

    The idea of manipulating flow to change its characteristics is over a century old. Manipulating instabilities of a jet to increase its mixing and to reduce its radiated noise started in the 1970s. While the effort has been successful in low-speed and low Reynolds number jets, available actuators capabilities in terms of their amplitude, bandwidth, and phasing have fallen short in control of high-speed and high Reynolds number jets of practical interest. Localized arc filament plasma actuators have recently been developed and extensively used at Gas Dynamics and Turbulence Laboratory (GDTL) for control of highspeed and high Reynolds number jets. While the technique has been quite successful and is very promising, all the work up to this point had been carried out using small high subsonic and low supersonic jets from a 2.54 cm diameter nozzle exit with a Reynolds number of about a million. The preliminary work reported in this paper is a first attempt to evaluate the scalability of the technique. The power supply/plasma generator was designed and built in-house at GDTL to operate 8 actuators simultaneously over a large frequency range (0 to 200 kHz) with independent control over phase and duty cycle of each actuator. This allowed forcing the small jet at GDTL with azimuthal modes m = 0, 1, 2, 3, plus or minus 1, plus or minus 2, and plus or minus 4 over a large range of frequencies. This power supply was taken to and used, with minor modifications, at the NASA Nozzle Acoustic Test Rig (NATR). At NATR, 32 actuators were distributed around the 7.5 in. nozzle (a linear increase with nozzle exit diameter would require 60 actuators). With this arrangement only 8 actuators could operate simultaneously, thus limiting the forcing of the jet at NATR to only three azimuthal modes m = plus or minus 1, 4, and 8. Very preliminary results at NATR indicate that the trends observed in the larger NASA facility in terms of the effects of actuation frequency and azimuthal modes are

  17. General Method for Calculating the Response and Noise Spectra of Active Fabry-Perot Semiconductor Waveguides With External Optical Injection

    DEFF Research Database (Denmark)

    Blaaberg, Søren; Mørk, Jesper

    2009-01-01

    We present a theoretical method for calculating small-signal modulation responses and noise spectra of active Fabry-Perot semiconductor waveguides with external light injection. Small-signal responses due to either a modulation of the pump current or due to an optical amplitude or phase modulation...

  18. Developing Internal Controls through Activities

    Science.gov (United States)

    Barnes, F. Herbert

    2009-01-01

    Life events can include the Tuesday afternoon cooking class with the group worker or the Saturday afternoon football game, but in the sense that Fritz Redl thought of them, these activities are only threads in a fabric of living that includes all the elements of daily life: playing, working, school-based learning, learning through activities,…

  19. 乘用车怠速车内噪声源识别及控制措施研究%Investigation on Noise Sources Identification and Control of Idling Noise inside Car

    Institute of Scientific and Technical Information of China (English)

    陈达亮; 李洪亮; 高辉; 车云龙

    2014-01-01

    In this paper, a car model of domestic brand is taken as research object to investigate the interior noise control in idling. The vibration isolation test of engine mounts and interior noises separation test, etc., are carried out to quantify contribution of different interior noise sources. Measures to improve interior noise control in idling are presented in this paper including control of noise source at exhaust outlet, control of suspension cushion structure transfer path, and control of air transfer path of firewall and sound-proof pad. With such modifications, the test car reduces its interior noise by 3.5 dB (A) in idling, which enables its noise level in line with that the noise level of Sino-foreign joint venture car products.%以某自主品牌乘用车怠速车内噪声为研究对象,通过动力总成悬置系统隔振率试验、车内噪声分离试验等方法定量确定车内各噪声源的贡献量大小,并从排气管口噪声源控制、悬置垫结构传递路径控制及防火墙隔音垫空气传递路径控制等方面分别提出怠速车内噪声控制的改进措施。采取改进措施后的试验样车怠速工况下车内噪声降低3.5dB(A),达到国内合资品牌水平。

  20. Vibration control of active structures an introduction

    CERN Document Server

    Preumont, Andre

    2002-01-01

    This text is an introduction to the dynamics of active structures and to the feedback control of lightly damped flexible structures. The emphasis is placed on basic issues and simple control strategies that work.

  1. The interference characteristics of platform and towed body noise in shallow water for active/passive towed array sonar

    Institute of Scientific and Technical Information of China (English)

    LI Qihu; LI Shuqiu; SUN Changyu; YU Huabing

    2007-01-01

    The interference characteristics of towed platform noise resulted from propeller and towed body for active/passive towed array is analyzed. It is shown that, in shallow water environment, the direct wave and bottom/sea surface reflected wave will seriously affect the performance of sonar system. The formula for calculating the direction of arrival (DOA) of interference in terms of various parameters, such as array depth, length of tow cable, is derived.The effect of interference noise for the detection performance of sonar system is described.The results of system simulation provide the method for reducing the effect of these kind of interferences.

  2. Sounds and Noises. A Position Paper on Noise Pollution.

    Science.gov (United States)

    Chapman, Thomas L.

    This position paper focuses on noise pollution and the problems and solutions associated with this form of pollution. The paper is divided into the following five sections: Noise and the Ear, Noise Measurement, III Effects of Noise, Acoustics and Action, and Programs and Activities. The first section identifies noise and sound, the beginnings of…

  3. 城市噪声污染及其治理研究%Study on the Urban Noise Pollution and Its Control

    Institute of Scientific and Technical Information of China (English)

    李建武

    2015-01-01

    分析了噪声污染的主要来源,阐述了城市噪声污染对人类的影响,提出了治理城市噪声污染问题的措施。%This paper analyzes the main sources of noise pollution, expounds the effects of urban noise pollution on humans, and puts forward some measures for controlling the urban noise pollution.

  4. Urban Environment Noise Analyzing and Control Countermeasure of Nanning City%南宁市环境噪声分析及污染防治对策

    Institute of Scientific and Technical Information of China (English)

    刘宝庆

    2011-01-01

    介绍了2009年南宁市环境噪声污染现状,分析了环境噪声污染的原因,最后提出了环境噪声污染防治对策.%Discussing urban environment noise state of Nanning city in 2009, the article analyzes the reasons of noise pollution and puts forward control countermeasure of noise pollution.

  5. 小型发电机的噪声治理%Noise control of portable genrtator set

    Institute of Scientific and Technical Information of China (English)

    侯美丽; 朱培恭; 侯丽

    2001-01-01

    In this paper,major noise sources in a portable generator set have been controlled.Constrained layer damping treatment and stiffening of the cooling fan cover had a combined effect of reducing the sound pressure level by about 3dB.Rigid clamping of the silencer also reduced the noise level.A partial enclosure reduced the sound pressure and power levels by about 4 and 3.7dB respectively.An overall noise reduction by 8.5dB was obtained on side 4 of the generator set as a result of the implementation of all the noise control measures.The noise reduction on the other sides of the generator set was also substantial.%本文对便携式发电机的噪声源进行了控制处理.约束阻尼层处理和冷却风扇盖硬化处理,可有效减小噪声级达3dB.紧固消音器也可减小噪声级.为发电机设计局部包围,局部包围分别减小声压级和声强级为4dB和3.7dB.同时使用上述噪声控制,第四面上噪声可减小8.5dB.其他面上的噪声也有相应的减小.

  6. Flow Field Simulation and Noise Control of a Twin-Screw Engine-Driven Supercharger

    Directory of Open Access Journals (Sweden)

    Tao Wang

    2016-01-01

    Full Text Available With the advantages of good low-speed torque capability and excellent instant response performance, twin-screw superchargers have great potential in the automobile market, but the noise of these superchargers is the main factor that discourages their use. Therefore, it is important to study their noise mechanism and methods of reducing it. This study included a transient numerical simulation of a twin-screw supercharger flow field with computational fluid dynamics software and an analysis of the pressure field of the running rotor. The results showed that overcompression was significant in the compression end stage of the supercharger, resulting in a surge in airflow to a supersonic speed and the production of shock waves that resulted in loud noise. On the basis of these findings, optimization of the supercharger is proposed, including expansion of the supercharger exhaust orifice and creation of a slot along the direction of the rotor spiral normal line at the exhaust port, so as to reduce the compression end pressure, improve the exhaust flow channel, and weaken the source of the noise. Experimental results showed that the noise level value of the improved twin-screw supercharger was significantly lower at the same speed than the original model, with an average decrease of about 5 dB (A.

  7. Optimal Bounded Control for Stationary Response of Strongly Nonlinear Oscillators under Combined Harmonic and Wide-Band Noise Excitations

    Directory of Open Access Journals (Sweden)

    Yongjun Wu

    2011-01-01

    Full Text Available We study the stochastic optimal bounded control for minimizing the stationary response of strongly nonlinear oscillators under combined harmonic and wide-band noise excitations. The stochastic averaging method and the dynamical programming principle are combined to obtain the fully averaged Itô stochastic differential equations which describe the original controlled strongly nonlinear system approximately. The stationary joint probability density of the amplitude and phase difference of the optimally controlled systems is obtained from solving the corresponding reduced Fokker-Planck-Kolmogorov (FPK equation. An example is given to illustrate the proposed procedure, and the theoretical results are verified by Monte Carlo simulation.

  8. Design of a 1 _s real-time low-noise data acquisition for power converters control loop

    CERN Document Server

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

    2015-01-01

    The proof of principle of a real-time data acquisition system to be integrated into a digital control loop for controlling the power converters of the Compact LInear Collider is presented. The system is based on an ultra low noise analogue front-end with 1:1 ppm RMS noise (referred to input), and about 1 _s of real-time delay. After the analogue conditioning, a fully-differential analogue-todigital converter is foreseen. The requirements of this system, directly derived from the accelerator performance, are discussed and translated into design specification. The results obtained by means of Pspice simulations are reported in order to prove that the design is feasible with the proposed architecture. Finally, the results of the experimental validation of the prototype, currently under design, will be included in the final paper.

  9. Wavelet filter based de-noising of weak neutron flux signal for dynamic control rod reactivity measurement

    Energy Technology Data Exchange (ETDEWEB)

    Park, Moon Ghu; Bae Sung Man; Lee, Chang Sup [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    2002-10-01

    The measurement and validation of control rod bank (group) worths are typically required by the start-up physics test standard programs for Pressurized Water Reactors (PWR). Recently, the method of DCRM{sup TM} (Dynamic Control rod Reactivity Measurement) technique is developed by KEPRI and will be implemented in near future. The method is based on the fast and complete bank insertion within the short period of time which makes the range of the reactivity variation very large from the below of the background gamma level to the vicinity of nuclear heating point. The weak flux signal below background gamma level is highly noise contaminated, which invokes the large reactivity fluctuation. This paper describes the efficient noise filtering method with wavelet filters. The performance of developed method is demonstrated with the measurement data at YGN-3 cycle 7.

  10. Efficient laser noise reduction by locking to an actively stabilized fiber interferometer with 10 km arm imbalance

    CERN Document Server

    Li, Dawei; Li, Shanglin; Li, Zhengbin; Zhao, Jianye

    2016-01-01

    We report a laser noise reduction method by locking it to an actively stabilized fiber-based Mach Zehnder interferometer with 10 km optical fiber to achieve large arm imbalance. An acousto optic modulator is used for interferometer stabilization and heterodyne detection. The out-of-loop frequency noise is reduced by more than 90 dB for Fourier frequency at 1 Hz. This structure presents an efficient laser noise reduction method both at high Fourier frequency and low Fourier frequency. The signal of stabilized laser is transferred via a 10 km fiber link with a fractional frequency stability of 1.12 times 10-16 at 1 s. Compared with the fractional frequency stability of that when the interferometer is not stabilized, more than one order of magnitude is improved.

  11. Use of noise attenuation modeling in managing missile motor detonation activities.

    Science.gov (United States)

    McFarland, Michael J; Watkins, Jeffrey W; Kordich, Micheal M; Pollet, Dean A; Palmer, Glenn R

    2004-03-01

    The Sound Intensity Prediction System (SIPS) and Blast Operation Overpressure Model (BOOM) are semiempirical sound models that are employed by the Utah Test and Training Range (UTTR) to predict whether noise levels from the detonation of large missile motors will exceed regulatory thresholds. Field validation of SIPS confirmed that the model was effective in limiting the number of detonations of large missile motors that could potentially result in a regulatory noise exceedance. Although the SIPS accurately predicted the impact of weather on detonation noise propagation, regulators have required that the more conservative BOOM model be employed in conjunction with SIPS in evaluating peak noise levels in populated areas. By simultaneously considering the output of both models, in 2001, UTTR detonated 104 missile motors having net explosive weights (NEW) that ranged between 14,960 and 38,938 lb without a recorded public noise complaint. Based on the encouraging results, the U.S. Department of Defense is considering expanding the application of these noise models to support the detonation of missile motors having a NEW of 81,000 lb. Recent modeling results suggest that, under appropriate weather conditions, missile motors containing up to 96,000 lb NEW can be detonated at the UTTR without exceeding the regulatory noise limit of 134 decibels (dB).

  12. Noise levels in the learning-teaching activities in a dental medicine school

    Science.gov (United States)

    Matos, Andreia; Carvalho, Antonio P. O.; Fernandes, Joao C. S.

    2002-11-01

    The noise levels made by different clinical handpieces and laboratory engines are considered to be the main descriptors of acoustical comfort in learning spaces in a dental medicine school. Sound levels were measured in five types of classrooms and teaching laboratories at the University of Porto Dental Medicine School. Handpiece noise measurements were made while instruments were running free and during operations with cutting tools (tooth, metal, and acrylic). Noise levels were determined using a precision sound level meter, which was positioned at ear level and also at one-meter distance from the operator. Some of the handpieces were brand new and the others had a few years of use. The sound levels encountered were between 60 and 99 dB(A) and were compared with the noise limits in A-weighted sound pressure level for mechanical equipments installed in educational buildings included in the Portuguese Noise Code and in other European countries codes. The daily personal noise exposure levels (LEP,d) of the students and professors were calculated to be between 85 and 90 dB(A) and were compared with the European legal limits. Some noise limits for this type of environment are proposed and suggestions for the improvement of the acoustical environment are given.

  13. A Mode Propagation Database Suitable for Code Validation Utilizing the NASA Glenn Advanced Noise Control Fan and Artificial Sources

    Science.gov (United States)

    Sutliff, Daniel L.

    2014-01-01

    The NASA Glenn Research Center's Advanced Noise Control Fan (ANCF) was developed in the early 1990s to provide a convenient test bed to measure and understand fan-generated acoustics, duct propagation, and radiation to the farfield. A series of tests were performed primarily for the use of code validation and tool validation. Rotating Rake mode measurements were acquired for parametric sets of: (i) mode blockage, (ii) liner insertion loss, (iii) short ducts, and (iv) mode reflection.

  14. 饲料厂噪声危害及治理%Noise Harm in Feed Mills and Its Control

    Institute of Scientific and Technical Information of China (English)

    刘建平

    2001-01-01

    The noise resources in feed mills and their harmfulness to human health were analyzed, and the controlling measures were approached so as to reduce environmental pollution.%通过对饲料厂噪声来源及对人体危害的分析,探讨其治理控制措施,减少对环境的污染。

  15. Fluids and Combustion Facility Acoustic Emissions Controlled by Aggressive Low-Noise Design Process

    Science.gov (United States)

    Cooper, Beth A.; Young, Judith A.

    2004-01-01

    The Fluids and Combustion Facility (FCF) is a dual-rack microgravity research facility that is being developed by Northrop Grumman Information Technology (NGIT) for the International Space Station (ISS) at the NASA Glenn Research Center. As an on-orbit test bed, FCF will host a succession of experiments in fluid and combustion physics. The Fluids Integrated Rack (FIR) and the Combustion Integrated Rack (CIR) must meet ISS acoustic emission requirements (ref. 1), which support speech communication and hearing-loss-prevention goals for ISS crew. To meet these requirements, the NGIT acoustics team implemented an aggressive low-noise design effort that incorporated frequent acoustic emission testing for all internal noise sources, larger-scale systems, and fully integrated racks (ref. 2). Glenn's Acoustical Testing Laboratory (ref. 3) provided acoustical testing services (see the following photograph) as well as specialized acoustical engineering support as part of the low-noise design process (ref. 4).

  16. An Improved Production Activity Control Architecture for Shop Floor Control

    Institute of Scientific and Technical Information of China (English)

    SHAHIDIkramullahButt; SUNHou-fang; HAMIDUllahKhanNiazi

    2005-01-01

    This paper presents a further improved Production Activity Control Architecture to deal with the complexity of information by creating Sub-Producers and Sub-Movers which will not only give a better control at workstation level but also reduce load on the Dispatcher. It also makes an analysis of the basic and improved PAC (Production Activity Control) Architecture in the Control System for Integrated Manufacturing. The PAC Architecture and the improvement will further enhance the flexibility and adaptability of the architecture in the ever changing environment of the Shop Floor Control (SFC) Systems.

  17. Estimate of ULF electromagnetic noise caused by a fluid flow during seismic or volcano activity

    Directory of Open Access Journals (Sweden)

    V. V. Surkov

    2014-10-01

    Full Text Available The elaboration of theoretical models, even oversimplified, capable to estimate an expected electromagnetic effect during earthquake preparation process is not less important than the advancement of observational technique to detect seismic-related electromagnetic emission. Here possible mechanisms of ULF electromagnetic noise associated with seismic or volcanic activity are discussed. The electrokinetic (EK and magnetohydrodynamic (MHD effects due to an irregular flow of conducting rock fluid or magma flow are being revised. The conventional theory of EK effect in a water-saturated rocks has been advanced by consideration of elliptic-shaped channels. A contribution of both mechanisms to observed ULF signal on the ground is shown to be dependent on the pore channel size/rock permeability. Estimates of magnetic and telluric perturbations caused by magma motion along a volcano throat indicate on the important role of the surrounding rock conductivity. These estimates have proven that the mechanisms under consideration are able to generate ULF electromagnetic emission which could be detected by modern magnetometers under favorable conditions.

  18. Optical control of antibacterial activity

    NARCIS (Netherlands)

    Velema, Willem A.; van der Berg, Jan Pieter; Hansen, Mickel J.; Szymanski, Wiktor; Driessen, Arnold J. M.; Feringa, Ben L.

    2013-01-01

    Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment. Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desir

  19. Noise Pollution

    Science.gov (United States)

    ... Overview » Title IV - Noise Pollution Title IV - Noise Pollution The 1990 Clean Air Act Amendments added a ... abatement 7642 Authorization of appropriations What is Noise Pollution? The traditional definition of noise is “unwanted or ...

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

    Data.gov (United States)

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