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Sample records for electret condenser microphone

  1. A Fully On-Chip Gm-Opamp-RC Based Preamplifier for Electret Condenser Microphones

    Science.gov (United States)

    Le, Huy-Binh; Ryu, Seung-Tak; Lee, Sang-Gug

    An on-chip CMOS preamplifier for direct signal readout from an electret capacitor microphone has been designed with high immunity to common-mode and supply noise. The Gm-Opamp-RC based high impedance preamplifier helps to remove all disadvantages of the conventional JFET based amplifier and can drive a following switched-capacitor sigma-delta modulator in order to realize a compact digital electret microphone. The proposed chip is designed based on 0.18µm CMOS technology, and the simulation results show 86dB of dynamic range with 4.5µVrms of input-referred noise for an audio bandwidth of 20kHz and a total harmonic distortion (THD) of 1% at 90mVrms input. Power supply rejection ratio (PSRR) and common-mode rejection ration (CMRR) are more than 95dB at 1kHz. The proposed design dissipates 125µA and can operate over a wide supply voltage range of 1.6V to 3.3V.

  2. A Micro-Machined Microphone Based on a Combination of Electret and Field-Effect Transistor.

    Science.gov (United States)

    Shin, Kumjae; Jeon, Junsik; West, James Edward; Moon, Wonkyu

    2015-08-18

    Capacitive-type transduction is now widely used in MEMS microphones. However, its sensitivity decreases with reducing size, due to decreasing air gap capacitance. In the present study, we proposed and developed the Electret Gate of Field Effect Transistor (ElGoFET) transduction based on an electret and FET (field-effect-transistor) as a novel mechanism of MEMS microphone transduction. The ElGoFET transduction has the advantage that the sensitivity is dependent on the ratio of capacitance components in the transduction structure. Hence, ElGoFET transduction has high sensitivity even with a smaller air gap capacitance, due to a miniaturization of the transducer. A FET with a floating-gate electrode embedded on a membrane was designed and fabricated and an electret was fabricated by ion implantation with Ga(+) ions. During the assembly process between the FET and the electret, the operating point of the FET was characterized using the static response of the FET induced by the electric field due to the trapped positive charge at the electret. Additionally, we evaluated the microphone performance of the ElGoFET by measuring the acoustic response in air using a semi-anechoic room. The results confirmed that the proposed transduction mechanism has potential for microphone applications.

  3. A Micro-Machined Microphone Based on a Combination of Electret and Field-Effect Transistor

    Directory of Open Access Journals (Sweden)

    Kumjae Shin

    2015-08-01

    Full Text Available Capacitive-type transduction is now widely used in MEMS microphones. However, its sensitivity decreases with reducing size, due to decreasing air gap capacitance. In the present study, we proposed and developed the Electret Gate of Field Effect Transistor (ElGoFET transduction based on an electret and FET (field-effect-transistor as a novel mechanism of MEMS microphone transduction. The ElGoFET transduction has the advantage that the sensitivity is dependent on the ratio of capacitance components in the transduction structure. Hence, ElGoFET transduction has high sensitivity even with a smaller air gap capacitance, due to a miniaturization of the transducer. A FET with a floating-gate electrode embedded on a membrane was designed and fabricated and an electret was fabricated by ion implantation with Ga+ ions. During the assembly process between the FET and the electret, the operating point of the FET was characterized using the static response of the FET induced by the electric field due to the trapped positive charge at the electret. Additionally, we evaluated the microphone performance of the ElGoFET by measuring the acoustic response in air using a semi-anechoic room. The results confirmed that the proposed transduction mechanism has potential for microphone applications.

  4. Sound localization in an anisotropic plate using electret microphones.

    Science.gov (United States)

    Hoseini Sabzevari, S Amir; Moavenian, Majid

    2017-01-01

    Acoustic source localization without knowing the velocity profile in anisotropic plates is still one of the most challenging areas in this field. The current time-of-flight based approaches for localization in anisotropic media, are based on using six high sampling sensors. The number of sensors and the corresponding large amount of data, would make those methods inefficient in practical applications. Although there are many different non-time-of-flight based approaches such as machine learning, or soft computing based methods that can be used for localization with a less number of sensors, they are not as accurate as time-of-flight based techniques. In this article, a new approach which requires only four low sampling rate sensors to localize acoustic source in an anisotropic plate is proposed. In this technique, four electret low sampling rate sensors in two clusters are installed on the plate surface. The presented method uses attenuation analysis in a suitable frequency band to decrease the number of sensors. The approach is experimentally tested and verified on an airplane composite nose by applying artificially generated acoustic emissions (Hsu-Nielsen source). The results reveal that the accuracy of proposed technique depends on distinction of dominant frequency band. A stethoscope as a physical filter is employed to reduce the sensitivity of the technique and delineation of frequency band. The suggested technique improves the accuracy of localization prediction. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. PECVD silicon nitride diaphragms for condenser microphones

    NARCIS (Netherlands)

    Scheeper, P.R.; Scheeper, P.R.; Voorthuyzen, J.A.; Voorthuyzen, J.A.; Bergveld, Piet

    1991-01-01

    The application of plasma-enhanced chemical vapour deposited (PECVD) silicon nitride as a diaphragm material for condenser microphones has been investigated. By means of adjusting the SiH4/NH3 gas-flow composition, silicon-rich silicon nitride films have been obtained with a relatively low tensile

  6. Fabrication of silicon condenser microphones using single wafer technology

    NARCIS (Netherlands)

    Scheeper, P.R.; van der Donk, A.G.H.; Olthuis, Wouter; Bergveld, Piet

    1992-01-01

    A condenser microphone design that can be fabricated using the sacrificial layer technique is proposed and tested. The microphone backplate is a 1-¿m plasma-enhanced chemical-vapor-deposited (PECVD) silicon nitride film with a high density of acoustic holes (120-525 holes/mm2), covered with a thin

  7. Ultra-low-noise preamplifier for condenser microphones.

    Science.gov (United States)

    Starecki, Tomasz

    2010-12-01

    The paper presents the design of a low-noise preamplifier dedicated for condenser measurement microphones used in high sensitivity applications, in which amplifier noise is the main factor limiting sensitivity of the measurements. In measurement microphone preamplifiers, the dominant source of noise at lower frequencies is the bias resistance of the input stage. In the presented solution, resistors were connected to the input stage by means of switches. The switches are opened during measurements, which disconnects the resistors from the input stage and results in noise reduction. Closing the switches allows for fast charging of the microphone capacitance. At low frequencies the noise of the designed preamplifier is a few times lower in comparison to similar, commercially available instruments.

  8. Benefits of the Fiber Optic versus the Electret Microphone in Voice Amplification

    Science.gov (United States)

    Kyriakou, Kyriaki; Fisher, Helene R.

    2013-01-01

    Background: Voice disorders that result in reduced loudness may cause difficulty in communicating, socializing and participating in occupational activities. Amplification is often recommended in order to facilitate functional communication, reduce vocal load and avoid developing maladaptive compensatory behaviours. The most common microphone used…

  9. Optimal design of an electret microphone metal-oxide-semiconductor field-effect transistor preamplifier.

    Science.gov (United States)

    van der Donk, A G; Bergveld, P

    1992-04-01

    A theoretical noise analysis of the combination of a capacitive microphone and a preamplifier containing a metal-oxide-semiconductor field-effect transistor (MOSFET) and a high-value resistive bias element is given. It is found that the output signal-to-noise ratio for a source follower and for a common-source circuit is almost the same. It is also shown that the output noise can be reduced by making the microphone capacitance as well as the bias resistor as large as possible, and furthermore by keeping the parasitic gate capacitances as low as possible and finally by using an optimum value for the gate area of the MOSFET. The main noise source is the thermal noise of the gate leakage resistance of the MOSFET. It is also shown that short-channel MOSFETs produce more thermal channel noise than longer channel devices.

  10. Hybrid method for determining the parameters of condenser microphones from measured membrane velocities and numerical calculations

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2009-01-01

    Typically, numerical calculations of the pressure, free-field, and random-incidence response of a condenser microphone are carried out on the basis of an assumed displacement distribution of the diaphragm of the microphone; the conventional assumption is that the displacement follows a Bessel...

  11. A MEMS Condenser Microphone-Based Intracochlear Acoustic Receiver.

    Science.gov (United States)

    Pfiffner, Flurin; Prochazka, Lukas; Peus, Dominik; Dobrev, Ivo; Dalbert, Adrian; Sim, Jae Hoon; Kesterke, Rahel; Walraevens, Joris; Harris, Francesca; Roosli, Christof; Obrist, Dominik; Huber, Alexander

    2017-10-01

    Intracochlear sound pressure (ICSP) measurements are limited by the small dimensions of the human inner ear and the requirements imposed by the liquid medium. A robust intracochlear acoustic receiver (ICAR) for repeated use with a simple data acquisition system that provides the required high sensitivity and small dimensions does not yet exist. The work described in this report aims to fill this gap and presents a new microelectromechanical systems (MEMS) condenser microphone (CMIC)-based ICAR concept suitable for ICSP measurements in human temporal bones. The ICAR head consisted of a passive protective diaphragm (PD) sealing the MEMS CMIC against the liquid medium, enabling insertion into the inner ear. The components of the MEMS CMIC-based ICAR were expressed by a lumped element model (LEM) and compared to the performance of successfully fabricated ICARs. Good agreement was achieved between the LEM and the measurements with different sizes of the PD. The ICSP measurements in a human cadaver temporal bone yielded data in agreement with the literature. Our results confirm that the presented MEMS CMIC-based ICAR is a promising technology for measuring ICSP in human temporal bones in the audible frequency range. A sensor for evaluation of the biomechanical hearing process by quantification of ICSP is presented. The concept has potential as an acoustic receiver in totally implantable cochlear implants.

  12. New Technology-Driven Approaches in the Design of Preamplifiers for Condenser Microphones

    DEFF Research Database (Denmark)

    Haas-Christensen, Jelena

    The topic of this thesis is the design of CMOS preamplifiers for condenser microphones. Increasingly popular type of condenser microphones are MEMS (micro-electro-mechanical) microphones which pose a stringent requirements to the design of interface electronics among other due to their increased...... noise. Besides that, as MEMS microphones are easy to integrate with CMOS circuitry, CMOS circuit design gains importance because it can contribute to the overall improved performance of the system by introducing extra functionalities. Possible methods of sensing a signal from the microphone...... are investigated and explained in the thesis. The method resulting in the overall best performance has been chosen for implementation. Due to the fact that the electronics noise performance is an important factor for minimization of the overall noise of the system, with 1/f noise dominant at low frequencies...

  13. Modified Skvor/Starr approach in the mechanical-thermal noise analysis of condenser microphone.

    Science.gov (United States)

    Tan, Chee Wee; Miao, Jianmin

    2009-11-01

    Simple analytical expressions of mechanical resistance, such as those formulated by Skvor/Starr, are widely used to describe the mechanical-thermal noise performance of a condenser microphone. However, the Skvor/Starr approach does not consider the location effect of acoustic holes in the backplate and overestimates the total equivalent mechanical resistance and mechanical-thermal noise. In this paper, a modified form of the Skvor/Starr approach is proposed to address this hole location dependent effect. A mode shape factor, which consists of the zero order Bessel and modified Bessel functions, is included in Skvor's mechanical resistance formulation to consider the effect of the hole location in the backplate. With reference to two B&K microphones, the theoretical results of the A-weighted mechanical-thermal noise obtained by the modified Skvor/Starr approach are in good agreements with those reported experimental ones.

  14. Characterization of condenser microphones under different environmental conditions for accurate speed of sound measurements with acoustic resonators

    Energy Technology Data Exchange (ETDEWEB)

    Guianvarc' h, Cecile; Pitre, Laurent [Laboratoire Commun de Metrologie LNE/Cnam, 61 rue du Landy, 93210 La Plaine Saint Denis (France); Gavioso, Roberto M.; Benedetto, Giuliana [Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Turin (Italy); Bruneau, Michel [Laboratoire d' Acoustique de l' Universite du Maine UMR CNRS 6613, av. Olivier Messiaen, 72085 Le Mans Cedex 9 (France)

    2009-07-15

    Condenser microphones are more commonly used and have been extensively modeled and characterized in air at ambient temperature and static pressure. However, several applications of interest for metrology and physical acoustics require to use these transducers in significantly different environmental conditions. Particularly, the extremely accurate determination of the speed of sound in monoatomic gases, which is pursued for a determination of the Boltzmann constant k by an acoustic method, entails the use of condenser microphones mounted within a spherical cavity, over a wide range of static pressures, at the temperature of the triple point of water (273.16 K). To further increase the accuracy achievable in this application, the microphone frequency response and its acoustic input impedance need to be precisely determined over the same static pressure and temperature range. Few previous works examined the influence of static pressure, temperature, and gas composition on the microphone's sensitivity. In this work, the results of relative calibrations of 1/4 in. condenser microphones obtained using an electrostatic actuator technique are presented. The calibrations are performed in pure helium and argon gas at temperatures near 273 K and in the pressure range between 10 and 600 kPa. These experimental results are compared with the predictions of a realistic model available in the literature, finding a remarkable good agreement. The model provides an estimate of the acoustic impedance of 1/4 in. condenser microphones as a function of frequency and static pressure and is used to calculate the corresponding frequency perturbations induced on the normal modes of a spherical cavity when this is filled with helium or argon gas.

  15. Detection System of Sound Noise Level (SNL) Based on Condenser Microphone Sensor

    Science.gov (United States)

    Rajagukguk, Juniastel; Eka Sari, Nurdieni

    2018-03-01

    The research aims to know the noise level by using the Arduino Uno as data processing input from sensors and called as Sound Noise Level (SNL). The working principle of the instrument is as noise detector with the show notifications the noise level on the LCD indicator and in the audiovisual form. Noise detection using the sensor is a condenser microphone and LM 567 as IC op-amps, which are assembled so that it can detect the noise, which sounds are captured by the sensor will turn the tide of sinusoida voice became sine wave energy electricity (altering sinusoida electric current) that is able to responded to complaints by the Arduino Uno. The tool is equipped with a detector consists of a set indicator LED and sound well as the notification from the text on LCD 16*2. Work setting indicators on the condition that, if the measured noise > 75 dB then sound will beep, the red LED will light up indicating the status of the danger. If the measured value on the LCD is higher than 56 dB, sound indicator will be beep and yellow LED will be on indicating noisy. If the noise measured value <55 dB, sound indicator will be quiet indicating peaceful from noisy. From the result of the research can be explained that the SNL is capable to detecting and displaying noise level with a measuring range 50-100 dB and capable to delivering the notification noise in audiovisual.

  16. A time-selective technique for free-field reciprocity calibration of condenser microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2003-01-01

    In normal practice, microphones are calibrated in a closed coupler where the sound pressure is uniformly distributed over the diaphragm. Alternatively, microphones can be placed in a free field, although in that case the distribution of sound pressure over the diaphragm will change as a result...

  17. Radiation impedance of condenser microphones and their diffuse-field responses

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2010-01-01

    The relation between the diffuse-field response and the radiation impedance of a microphone has been investigated. Such a relation can be derived from classical theory. The practical measurement of the radiation impedance requires (a) measuring the volume velocity of the membrane of the microphon...

  18. General considerations of noise in microphone preamplifiers

    NARCIS (Netherlands)

    van der Donk, A.G.H.; van der Donk, A.G.H.; Voorthuyzen, J.A.; Voorthuyzen, J.A.; Bergveld, Piet

    1991-01-01

    In this paper a study of the noise performance of electret microphone systems as a part of hearing aids is presented. The signal-to-noise ratio of the microphone-preamplifier combination, containing a field-effect transistor (FET) and a high value resistive bias element in a hybrid configuration, is

  19. A low-voltage silicon condenser microphone for hearing instrument applications

    DEFF Research Database (Denmark)

    Rombach, Pirmin; Müllenborn, Matthias; Klein, Udo

    1999-01-01

    .g., membrane and back plate, a dedicated process sequence has been developed. Therefore, circuitry and mechanical parts have to be produced separately and mounted later in a stacking process. The microphone has a 2×2 mm2, 0.4 µm-thick membrane and an air gap of 1.0 µm. Wafers with different membrane stress...... have been produced. The microphones have been acoustically, mechanically, and electrically characterized, partly on wafer-scale, and compared with an acoustical/electrical lumped element model. The sensitivity for the low-stress microphones using a 1.5 V power supply is about 7.0 mV/Pa and the input...

  20. Noise in miniature microphones.

    Science.gov (United States)

    Thompson, Stephen C; LoPresti, Janice L; Ring, Eugene M; Nepomuceno, Henry G; Beard, John J; Ballad, William J; Carlson, Elmer V

    2002-02-01

    The internal noise spectrum in miniature electret microphones of the type used in the manufacture of hearing aids is measured. An analogous circuit model of the microphone is empirically fit to the measured data and used to determine the important sources of noise within the microphone. The dominant noise source is found to depend on the frequency. Below 40 Hz and above 9 kHz, the dominant source is electrical noise from the amplifier circuit needed to buffer the electrical signal from the microphone diaphragm. Between approximately 40 Hz and 1 kHz, the dominant source is thermal noise originating in the acoustic flow resistance of the small hole pierced in the diaphragm to equalize barometric pressure. Between approximately 1 kHz and 9 kHz, the noise originates in the acoustic flow resistances of sound entering the microphone and propagating to the diaphragm. To further reduce the microphone internal noise in the audio band requires attacking these sources. A prototype microphone having reduced acoustical noise is measured and discussed.

  1. A microflown based sound presure microphone suitable for harsh environments

    NARCIS (Netherlands)

    Yntema, Doekle Reinder; de Bree, H.E.

    2005-01-01

    There are several cases where a sound field reconstruction or prediction is required under harsh conditions such as high temperature, humidity or chemical attack. A regular pressure microphone will not last long under these conditions. Electret based pressure microphones stop working well above 70

  2. The magnetoactive electret

    Science.gov (United States)

    Monkman, G. J.; Sindersberger, D.; Diermeier, A.; Prem, N.

    2017-07-01

    A magnet which adheres to every surface, not only those of ferromagnetic materials, has hitherto been the domain of science fiction. Now for the first time such a novel device exists. The fusion of a permanently magnetized magnetoactive polymer containing hard magnetic particles and an electret enhanced with ferroelectric particles has resulted in the development of a new smart device—the magnetoactive electret. Magnetoactive electrets can be made to exhibit the usual magnetic properties of permanent magnetism together with the electrostatic properties of electrets. This results in simultaneous magnetoadhesion and electroadhesion forces from the same elastomeric element. The biasing field, needed to avoid discontinuities concerned with transition through the zero point in operating curves, is normally provided by means of either a magnetic or an electric field. This novel technology provides both bias options in a single device.

  3. Solid state silicon based condenser microphone for hearing aid, has transducer chip and IC chip between intermediate chip and openings on both sides of intermediate chip, to allow sound towards diaphragm

    DEFF Research Database (Denmark)

    2000-01-01

    towards diaphragm. Surface of the chip (2) has electrical conductors (14) to connect chip with IC chip (3). USE - For use in miniature electroacoustic devices such as hearing aid. ADVANTAGE - Since sound inlet is covered by filter, dust, moisture and other impurities do not obstruct interior and sound...... inlet of microphone. External electrical connection can be made economically reliable and the thermal stress is avoided with the small size solid state silicon based condenser microphone....

  4. Electret dosemeter for beta radiation

    International Nuclear Information System (INIS)

    Campos, L.L.; Caldas, L.V.E.; Mascarenhas, S.

    The response characteristics of an electret dosemeter for beta radiation are studied. Experiments were performed using different geometries and walls, and it was verified for which geometry the dosemeter sensitivity is greater. Sources of 90 Sr - 90 Y, 204 Tl and 85 Kr were used in the experiments. (I.C.R.) [pt

  5. Condensers

    International Nuclear Information System (INIS)

    Andrieux, M.B.

    1984-01-01

    Characteristics of the condenser cooling waters of various French 900 MW nuclear power plants. Design and description of various types of condensers: condensers feeded directly with river water, condensers feeded by cooling towers, condensers feeded with sea water of brackish water. Presentation of the main problems encountered with the brass bundles (ammoniacal corrosion, erosion of the peripheral tubes, vibrations of the tubes), with the titanium bundles, with the tubular plates, the tubes-tubular plates assemblies, the coatings of the condenser water chamber (sea water), the vapor by-pass and with the air inlet. Analysis of the in service performances such as condensation pressure, oxygen content and availability [fr

  6. Response of electret dosemeter to slow neutrons

    International Nuclear Information System (INIS)

    Ghilardi, A.J.P.; Pela, C.A.; Zimmerman, R.L.

    1987-01-01

    The response of electret dosemeter to slow neutrons exposure is cited, mentioning the preparation and the irradiation of dosemeter with Am-Be source. Some theory considerations about the response of electret dosemeter to slow and fast neutrons are also presented. (C.G.C.) [pt

  7. A new electret dosemeter for radiotherapy

    International Nuclear Information System (INIS)

    Rodrigues, L.N.

    1985-01-01

    The results obtained with a new plane electret dosemeter for use in Radiotherapy are presented. The working principle of the electret dosemeter in based on the use of the electret field the ion collecting field, similarly to an ionization chamber, and as charge integrator detector. The dosemeter had, initialy, a cylindrical geometry. The results attained with it's calibration curve concerning the sensitivity, the stability and the reproducibility lead to changes in the dosemeter geometry. A plane geometry dosemeter was built in order to increase the useful exposure range. The plane dosemeter sensitivity dependence was measured versus the electret charging conditions, the chamber volume and wall material (aluminium, brass and stainless steel). The stainless steel dosemeter showed the best results. This dosemeter has the following characteristics: sensitivity 10 -13 C/R, volume 0.20 cm 3 . Compared to the Baldwin-Farmer dosemeter, this results are fairly good. A multiple electret dosemeter was developed to monitor the uniformity of the radiation beam for a Cobalt Teletherapy unit. The intercomparasion with the Baldwin-Farmer unit presented a maximum variation of 3%. (author) [pt

  8. Charge distribution and stability in electret materials

    DEFF Research Database (Denmark)

    Thyssen, Anders

    The objective of the work presented in this Ph.D. thesis is to give a broader understanding of which key parameters influence the charge stability of polymer electrets, and how the electrical charges are distributed. This has been achieved using polypropylene as an electret polymer model system......-PP and i-PP, is because the charge retention is extremely sensitive to the sample preparation. This was seen in regard to the thermal history of the samples and the influence of micron and nano size particles in the polymer electret. Through adding micron and nano size calcium carbonate and aluminium oxide....... By means of kinetic rate theory the discharge behaviour could be explained for polypropylene when thermally stimulated. This resulted in the determination of several activation energies, which could be used for describing the discharging seen at isothermal conditions. This theory is a powerful tool...

  9. Response of electret dosemeter to slow neutrons

    International Nuclear Information System (INIS)

    Ghilardi, A.J.P.; Pela, C.A.; Zimmerman, R.L.

    1987-01-01

    The response of the electret dosemeter to exposition of slow neutrons is studied. Different external coatings are used on the dosemeter (polyethylene, alminium, polyethylene + boron, aluminium + boron) and exposure curves (with and without water) are compared. (M.A.C.) [pt

  10. Invisible Surface Charge Pattern on Inorganic Electrets

    DEFF Research Database (Denmark)

    Wang, Fei; Hansen, Ole

    2013-01-01

    We propose an easy method to pattern the surface charge of ${\\rm SiO}_{2}$ electrets without patterning the dielectric layer. By eliminating the use of metal guard electrodes, both the charge efficiency and the surface charge stability in humid environments improve. We apply the concept...

  11. Charge stabilization on the electret dosemeter

    International Nuclear Information System (INIS)

    Pela, C.A.; Guilardi, A.J.P.; Ghilardi Netto, T.

    1987-01-01

    The charge stabilization and how eliminate the humidity effects in electret dosemeter are shown. The charge measure along of time, changing with the humidity is observed. The fabrication of dryness chamber with silica gel for a more adequate use of dosemeter in differents physical conditions of environment is also cited. (C.G.C.) [pt

  12. Collecting Protein Biomarkers in Breath Using Electret Filters: A Preliminary Method on New Technical Model and Human Study.

    Directory of Open Access Journals (Sweden)

    Wang Li

    Full Text Available Biomarkers in exhaled breath are useful for respiratory disease diagnosis in human volunteers. Conventional methods that collect non-volatile biomarkers, however, necessitate an extensive dilution and sanitation processes that lowers collection efficiencies and convenience of use. Electret filter emerged in recent decade to collect virus biomarkers in exhaled breath given its simplicity and effectiveness. To investigate the capability of electret filters to collect protein biomarkers, a model that consists of an atomizer that produces protein aerosol and an electret filter that collects albumin and carcinoembryonic antigen-a typical biomarker in lung cancer development- from the atomizer is developed. A device using electret filter as the collecting medium is designed to collect human albumin from exhaled breath of 6 volunteers. Comparison of the collecting ability between the electret filter method and other 2 reported methods is finally performed based on the amounts of albumin collected from human exhaled breath. In conclusion, a decreasing collection efficiency ranging from 17.6% to 2.3% for atomized albumin aerosol and 42% to 12.5% for atomized carcinoembryonic antigen particles is found; moreover, an optimum volume of sampling human exhaled breath ranging from 100 L to 200 L is also observed; finally, the self-designed collecting device shows a significantly better performance in collecting albumin from human exhaled breath than the exhaled breath condensate method (p0.05. In summary, electret filters are potential in collecting non-volatile biomarkers in human exhaled breath not only because it was simpler, cheaper and easier to use than traditional methods but also for its better collecting performance.

  13. Modelling measurement microphones using BEM with visco-thermal losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller

    2012-01-01

    For many decades, models that can explain the behaviour of measurement condenser microphones have been proposed in the literature. These devices have an apparently simple working principle, a charged capacitor whose charge varies when one of its electrodes, the diaphragm, moves as a result of sound...... waves. However, measurement microphones must be manufactured very carefully due to their sensitivity to small changes of their physical parameters. There are different elements in a microphone, the diaphragm, the gap behind it, a back cavity, a vent for pressure equalization and an external medium. All...... visco-thermal losses is used to model measurement condenser microphones. The models presented are fully coupled and include a FEM model of the diaphragm. The behaviour of the acoustic variables in the gap and the effect of the pressure equalization vent are discussed, as well as the practical difficulty...

  14. Inorganic electret with enhanced charge stability for energy harvesting

    DEFF Research Database (Denmark)

    Wang, Fei; Hansen, Ole

    2013-01-01

    We report a new surface treatment of inorganic electret materials which enhances the charge stability. Coating the surfaces with 1H, 1H, 2H, 2H - perfluorodecyltrichlorosilane (FDTS) makes the electret surface more hydrophobic which improves the surface charge stability under high humidity condit...... conditions. Thermal tests show that the thermal stability of charge in the inorganic electrets is also much better than that of polymer materials such as CYTOP. A demonstrator device with SiO2 electrets shows promising results for energy harvesting applications....

  15. Radon monitoring technique with electret collecting

    International Nuclear Information System (INIS)

    Tian Zhiheng; Zuo Fuqi; Xiao Detao; Zhao Xkiuliang

    1991-12-01

    The integrating radon monitoring technique with electret collecting is a method which collects the 218 Po + positive ions by electrostatic field produced by electret. It has greatly improved the sensitivity of radon measurement. The response factor of this method reaches to 4.7 cm -2 Bq -1 m 3 h -1 , 1000 times larger than that of common passive sampling method. The monitoring device and its principle are introduced. The measuring results of radon concentration and radon flux rate and quality assurance system by using this method in the Qinshan Nuclear Power Plant, Human Environmental Monitoring Central Station and some uranium mines are also presented. The analytical results show that the radon concentration in the Qinshan Nuclear Power Plant is affected by wind direction. When wind directs toward sea, the radon concentration is high. If the wind is to the contrary, it is low. The radon concentration ratio of both is about 2

  16. Electret Stability Related to the Crystallinity in Polypropylene

    DEFF Research Database (Denmark)

    Thyssen, Anders; Almdal, Kristoffer; Thomsen, Erik Vilain

    2015-01-01

    Through mixing isotactic-polypropylene (i-PP) and atactic-polypropylene (a-PP), we have demonstrated the importance of the crystallinity in polypropylene as an electret material. A high degree of crystallinity in polypropylene, used as an electret, gives a better charge stability towards...

  17. New DRIE-Patterned Electrets for Vibration Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Chaillout J.-J.

    2012-10-01

    Full Text Available This paper is about a new manufacturing process aimed at developing stable SiO2/Si3N4 patterned electrets using a Deep Reactive Ion Etching (DRIE step for an application in electret-based Vibration Energy Harvesters (e-VEH. This process consists in forming continuous layers of SiO2/Si3N4 electrets in order to limit surface conduction phenomena and is a new way to see the problem of electret patterning. Experimental results prove that patterned electrets charged by a positive corona discharge show excellent stability with high surface charge densities that may reach 5mC/m2 on 1.1μm-thick layers, even with fine patterning and harsh temperature conditions (up to 250°C. This paves the way to new e-VEH designs and manufacturing processes.

  18. On determination of microphone response and other parameters by a hybrid experimental and numerical method

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Jacobsen, Finn; Rasmussen, Knud

    2008-01-01

    Typically, numerical calculations of the pressure, free-field and random-incidence response of a condenser microphone are carried out on the basis of an assumed displacement distribution of the diaphragm of the microphone; the conventional assumption is that the displacement follows a Bessel...

  19. Electret Stability Related to Spherulites in Polypropylene

    DEFF Research Database (Denmark)

    Thyssen, Anders; Almdal, Kristoffer; Thomsen, Erik Vilain

    2015-01-01

    Electret charge stability has been related to the size of the spherulites in polypropylene. As the size of the spherulites is decreased the stability is increased. This is seen for isothermal conditions at 90 °C and 120 °C as well as for 90 % relative humidity at 50 °C. The charge release...... temperature is also increased in thermally stimulated voltage discharge experiments as the size of the spherulites is decreased. The size of the spherulites is controlled though the cooling rate from polypropylenes liquid state....

  20. Study on the electrostatic and piezoelectric properties of positive polypropylene electret cyclosporine A patch

    International Nuclear Information System (INIS)

    Guo, X; Liang, Y Y; Jiang, J; Liu, H Y; Cui, L L

    2013-01-01

    Corona charged electrets at voltages of +500 V, +1000 V and +1500 V were prepared for manufacturing polypropylene (PP) electret blank patches and PP electret drug patches. The stability of external electrostatic field of the electret patch and the polarization of the drug in patch under the internal electrostatic field of the electret were studied. The results indicate that all the electret drug patches had good charge storage stabilities. However, the non-electrode coated electret drug patch had better stability in the external electrostatic field than that of the electrode coated electret drug patch. The higher the charging voltage of the electret, the faster the surface potential of the electret drug patch decayed, and the worse the stability of the external electrostatic field. All the electrets used in this study could result in the polarization of the model drug in patch. The piezoelectric properties of non-electrode coated electret drug patch increased with the charging voltage of the electret. However, excessively higher charging voltage could result in the decreased polarization of the drug in patch. Both the stability of the external electrostatic field of electret and the polarization of drug were the key factors for controlled drug release and skin permeation.

  1. Photo-electret effects in homogenous semiconductors

    International Nuclear Information System (INIS)

    Nabiev, G.A.

    2004-01-01

    In the given work is shown the opportunity and created the theory of photo-electret condition in semiconductors with Dember mechanism of photo-voltage generation. Photo-electret of such type can be created, instead of traditional and without an external field as a result of only one illumination. Polar factor, in this case, is the distinction of electrons and holes mobility. Considered the multilayered structure with homogeneous photoactive micro areas shared by the layers, which are interfering to alignment of carriers concentration. We consider, that the homogeneous photoactive areas contain deep levels of stick. Because of addition of elementary photo voltage in separate micro photo cells it is formed the abnormal-large photo voltage (APV-effect). Let's notice, that Dember photo-voltage in a separate micro photo-cell ≤kT/q. From the received expressions, in practically important, special case, when quasi- balance between valent zone and stick levels established in much more smaller time, than free hole lifetime, and we received, that photo-voltage is relaxing. Comparing of the received expressions with the laws of photo voltage attenuation in p-n- junction structures shows their identity; the difference is only in absolute meanings of photo voltage. During the illumination in the semiconductor are created the superfluous concentration of charge carriers and part from them stays at deep levels. At de-energizing light there is a gradual generation of carriers located at these levels

  2. A novel vibrational energy harvester with electric double layer electrets

    Science.gov (United States)

    Ono, S.; Miwa, K.; Iori, J.; Mitsuya, H.; Ishibashi, K.; Sano, C.; Toshiyoshi, H.; Fujita, H.

    2016-11-01

    We propose a new type of vibrational energy harvester with an electric double layer (EDL) electrets. Instead of using any external bias-voltage source or dielectric layer on top of the metal electrode to sustain EDL, we succeed to anchor the ions to polymer network to form the EDL electrets. By changing contact area between the EDL electrets and the electrode, large electric current is generated in the circuit. Owing to extremely large capacitance of the EDL electret, vibrational energy harvesters have the unique capability to leverage the high- density charge accumulation to the electrode and obtained current density becomes as high as 200 μA/cm2 with output voltage of 1V even with low frequency vibrations as low as 1 Hz.

  3. Electret filters for high-efficiency and high-flow air cleaning

    NARCIS (Netherlands)

    Turnhout, J. van; Hoeneveld, W.J.; Adamse, J.W.C.; Rossen, L.M. van

    1981-01-01

    Electret filter systems are described. A method is outlined for the production of electret filters and results are presented on the performance of the filters in relation to aerosols. Applications for these filters are indicated.

  4. Comparative enhancing effects of electret with chemical enhancers on transdermal delivery of meloxicam in vitro

    International Nuclear Information System (INIS)

    Cui, L L; Hou, X M; Li, G D; Jiang, J; Liang, Y Y; Xin, X

    2008-01-01

    Electret offers enhancing effect in transdermal drug delivery for altering of the arrangement of lipid molecules in the stratum corneum, forming many transient permeable apertures and enhancing the transdermal drug delivery. In this paper, meloxicam patch formulations were developed to make the comparative study of transdermal drug delivery between electret and chemical enhancers. Patches were made into control, electret, chemical enhancer and electret with chemical enhancer ones, according to the preparation procedure. The electret combined with chemical enhancer patch was designed to probe the incorporation between electret and chemical enhancer in transdermal drug delivery. The meloxicam release from the patch was found to increase in order of blank, chemical enhancer, electret and electret with chemical enhancer patch, in general.

  5. Static pressure and temperature coefficients of laboratory standard microphones

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1996-01-01

    The sensitivity of condenser measurement microphones depends on the environmental conditions due to the changes in the acoustic properties of the enclosed air between diaphragm and back-electrode and in the cavity behind the backelectrode. A theoretical investigation has been performed based...... on an extended lumped parameter representation of the mechanical and acoustical elements of the microphone, assuming the velocity distribution of the diaphragm to follow the zero-order Bessel function. The extension involves the frequency dependency of the dynamic diaphragm mass and stiffness as well as a first...

  6. The static pressure and temperature coefficients of laboratory standard microphones

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1999-01-01

    The sensitivity of condenser measurement microphones depends on the environmental conditions due to the changes in the acoustic properties of the air enclosed between diaphragm and backelectrode and in the cavity behind the backelectrode. A theoretical investigation has been performed based...... on an extended lumped parameter representation of the mechanical and acoustic elements of the microphone. The extension involves the frequency dependency of the dynamic diaphragm mass and stiffness as well as a first-order approximation of resonances in the back cavity. It was found that each coefficient...

  7. Changing to electret by low energy radiation

    International Nuclear Information System (INIS)

    Fukuchi, Ryoichi; Nonomura, Takuo; Sekiguchi, Takashi; Tsuchiya, Mitsuaki

    1990-01-01

    The surface potential, surface charge density and thermally stimulated current of the FEP films which were changed to electrets by irradiating 170 keV electron beam were measured, and the relationship among their measured values was investigated. As the result, it was known that the mean value of surface potential was proportional to surface charge density. Besides, according to the results of measurement of surface charge density and thermally stimulated current, also positive charges seemed to exist in the samples irradiated with electron beam. The measurements of surface potential, surface charge density and thermally stimulated current are reported. There are the FEP film surfaces irradiated with electron beam on which potential distributed largely changing from positive to negative, and on which only negative potential distributed with relatively small change. Thermally stimulated current is due to the polarization in samples and the relaxation phenomena of trapped charges. As FEP is assumed to be without polarity, the latter cause is conceivable, and also positive charges seemed to exist. (K.I.)

  8. Electret Stability Related to the Crystallinity in Polypropylene

    DEFF Research Database (Denmark)

    Thyssen, Anders; Almdal, Kristoffer; Thomsen, Erik Vilain

    2017-01-01

    preparation processes and characteristics can be identical. This is important since the performance of an electret material is sensitive to its previous process history. Activation energies used for predicting the thermal potential decay are determined from thermally stimulated current and isothermal......Through mixing isotactic-polypropylene (i-PP) and atactic-polypropylene (a-PP), we have demonstrated the importance of the crystallinity in polypropylene as an electret material. Samples with crystallinities between 7 % and 47 % were used. A high degree of crystallinity in polypropylene, used...

  9. Silicon microphones - a Danish perspective

    DEFF Research Database (Denmark)

    Bouwstra, Siebe; Storgaard-Larsen, Torben; Scheeper, Patrick

    1998-01-01

    Two application areas of microphones are discussed, those for precision measurement and those for hearing instruments. Silicon microphones are under investigation for both areas, and Danish industry plays a key role in both. The opportunities of silicon, as well as the challenges and expectations......, are discussed. For precision measurement the challenge for silicon is large, while for hearing instruments silicon seems to be very promising....

  10. Flexible autonomous scavengers: the combination of dielectric polymers and electrets

    Science.gov (United States)

    Jean-Mistral, C.; Vu Cong, T.; Sylvestre, A.

    2012-04-01

    Thanks to their high energy density and their flexibility, scavenging energy with dielectric polymer is a promising alternative to ensure the autonomy of various sensors such as in e-textiles or biomedical applications. Nevertheless, they are passive materials requiring a high bias voltage source to polarize them. Thus, we present here a new design of scavenger using polymer electrets for poling the dielectric polymer. Our scavenger is composed of commercial dielectric polymer (3M VHB 4910) with Teflon electrets developing a potential of -300V, and patterned grease electrodes. The transducer works in a pure shear mode with a maximal strain of 50% at 1Hz. The typical "3D-textured" structure of the scavenger allows the electrets to follow the movement of the dielectric. A complete electromechanical analytical model has been developed thank to the combination of electrets theory and dielectric modelling. Our new autonomous structure, on an optimal resistance, can produce about 0.637mJ.g-1.

  11. Digital computerized eletrometric system for radiation dosimetry with electrets

    International Nuclear Information System (INIS)

    Cruvinel, P.E.; Mascarenhas, S.; Rodrigues, A.R.D.; Farias, M.A.C.

    1985-01-01

    A Digital Computerized Eletrometric System for radiation dosimetry with electrets is presented. The measurement of the charge on the dosimeter and corresponding dose as well as the identification of up to 1024 users are reported. The operation in automatic and manual mode such as the use of the system as 'clock register' are described. (M.A.C.) [pt

  12. Pressure reciprocity calibration of a MEMS microphone.

    Science.gov (United States)

    Wagner, Randall P; Fick, Steven E

    2017-09-01

    This article reports the first use of the pressure reciprocity technique to calibrate a micro-electromechanical system (MEMS) microphone. This standardized primary calibration method is conventionally used to calibrate laboratory standard microphones. Results for the pressure reciprocity calibration of a MEMS microphone and two laboratory standard microphones are presented for the frequency range 100-10 000 Hz. Because the amplifier in the MEMS microphone package prevents reciprocal operation, this microphone was used only as a receiver of sound. A description of the procedure is presented along with checks of the measurement results and data regarding the uncertainties of these results.

  13. Influence of porous PTFE/LDPE/PP composite electret in skin ultrastructure

    International Nuclear Information System (INIS)

    Jiang, J; Liang, Y Y; Tang, Y; Ye, X T; Yang, Y J; Song, M H; Cui, L L; Hou, X M

    2008-01-01

    Corona charging and heat melting method were used to prepare porous PTFE electret and porous PTFE/LDPE/PP composite electret, respectively. After 0.5, 1, 1.5, 3 and 4 hour's action of fluorescein sodium (FINa) and -300V porous PTFE/LDPE/PP composite electret on the excised abdominal skin of rat, the skin structure was studied by means of scanning electron microscopy, transmission electron microscopy and confocal laser scanning microscopy, respectively, to probe the mechanism of electret on transdermal drug delivery. The results indicated that negative electret could increase the transdermal delivery of FINa due to its effect on changing the organized structure of stratum corneum, enlarging the hair follicles, which may be the mechanism of electret in enhancing transdermal drug delivery.

  14. Review of Electret ion chamber technology for measuring technologically enhanced natural radioactivity

    International Nuclear Information System (INIS)

    Kotrappa, P.

    2002-01-01

    Electret ion chamber (EIC) is a passive integrating ionization chamber used extensively for measuring technologically enhanced radioactivity. Commercially available electret ion chambers called 1E-PERM (Electret-Passive Environmental Radiation Monitors) electret ion chambers are relatively new and are in use only from the past 10 years. The EIC consists of a stable electret (electrically charged Teflon disc) mounted inside an electrically conducting chamber. The electret serves both as a source of the electric field and as a sensor. The ions produced inside the chamber are collected by the electret. The reduction in charge of the electret is related to total ionization during the period of exposure. This charge reduction is measured using a battery operated electret reader. Using appropriate calibration factors and the exposure time, the desired parameters such as radon concentration in air is calculated. These low cost monitors require neither power nor battery and several hundreds of these can be used simultaneously and serviced by one reader. These monitors do not provide on line readings, but provide an average value over a period of time. The EICs have been used for measuring: (a) indoor and outdoor radon, (b) thoron, (c) dissolved radon and radium in water, (d) environmental gamma, (e) radon emanating radon concentration in soil samples and in pipes, (f) radon flux from surfaces and building materials. The purpose of this paper is to describe these methods and give selected reference to the related publications for more detailed reading. (author)

  15. Two-wire Interface for Digital Microphones

    NARCIS (Netherlands)

    Groothedde, Wouter; Klumperink, Eric A.M.; Nauta, Bram; Eschauzier, Rudolphe Gustave Hubertus; van Rijn, Nico

    2003-01-01

    A two-wire interface for a digital microphone circuit includes a power line and a ground line. The interface utilizes the ground line as a "voltage active line" to transmit both clock and data signals between the digital microphone circuit and a receiving circuit. The digital microphone circuit

  16. Two-Wire interface for digital microphones

    NARCIS (Netherlands)

    Groothedde, Wouter; Klumperink, Eric A.M.; Nauta, Bram; Eschauzier, Rudolphe Gustave Hubertus; van Rijn, Nico

    2005-01-01

    A two-wire interface for a digital microphone circuit includes a power line and a ground line. The interface utilizes the ground line as a "voltage active line" to transmit both clock and data signals between the digital microphone circuit and a receiving circuit. The digital microphone circuit

  17. Efficiency of Electret Polycarbonate Nonwovens in Respiratory Protection Against Nanoparticles

    Directory of Open Access Journals (Sweden)

    Brochocka Agnieszka

    2017-06-01

    Full Text Available Toxicological research on the influence of noxious nanoparticles on human health indicates the need to develop efficient protective devices. In particular, this concerns respiratory protective equipment employing filtration nonwovens. This paper presents a methodology for the improvement of the filtration efficiency of electret nonwovens against nanoparticles by enriching amorphous polycarbonate (PC with additives of different electrostatic potentials. We introduced perlite granules (positive charge and amber granules (negative charge to the polymer stream in melt-blown technology. Filtration efficiency was assessed by a standard method using paraffin oil and sodium chloride aerosol, as well as by a non-standard method using NaCl nanoparticles. The experiments showed that strengthening the effects of electrostatic forces by the introduction of modifiers is a promising approach to improving the efficiency of electret nonwovens against nanoparticles.

  18. A portable electronic system for radiation dosimetry using electrets

    Science.gov (United States)

    Cruvinel, P. E.; Mascarenhas, S.; Cameron, J.

    1990-02-01

    An electret dosimeter with a cylindrical active volume has been introduced by Mascarenhas and collaborators [Proc. 10th Anniversary Conf. 1969-1979, Associacâo Brasileira de Fisicos em Medicina, p. 488; Topics Appl. Phys. 33 (1987) 321] for possible use in personnel and area monitoring. The full energy response curve as well as the degree of reproducibility and accuracy of the dosimeter are reported in a previous report [O. Guerrini, Master Science Thesis, São Carlos, USP-IFQSC (1982)]. For dimensions similar to those of the common pen dosimeter, the electret has a total surface charge of the order of 10 -9 C and it has a readout sensitivity of the order of 10 -5 Gy with a useful range of 5 × 10 -2 Gy. In this paper we describe a portable electronic system to measure X and γ-rays using a cylindrical electret ionization chamber. It uses commercially available operational amplifiers, and charge measurements can also be made by connecting a suitable capacitor in the feedback loop. With this system it is possible to measure equivalent surface charges up to (19.99±0.01) on the dosimeter. The readout doses are shown on a 3 {1}/{2} digit liquid crystal display (LCD). We have used complementary metal oxide semiconductor (CMOS) and bipolar metal oxide semiconductor (BiMOS) operatonal amplifier devices in the system's design. This choice provides small power consumption and is ideal for battery powered instruments. Furthermore the instrument is ideally suited for in situ measurements of X and γ radiation using a cylindrical electret ionization chamber.

  19. Evaluation of Electrostatic Force on Bipolar Charged Electret

    International Nuclear Information System (INIS)

    Sonoda, K; Minami, K; Miwatani, N; Fujita, T; Kanda, K; Maenaka, K

    2014-01-01

    This paper presents an evaluation of an electrostatic vibration energy harvester with the bipolar charged electret. The energy harvester with the size of 13 × 12 × 1.2 mm 3 was fabricated. The output power of the bipolar charged with ±250 V harvester was 9 μW when the acceleration was 1.4 g at 352 Hz with 0.9 MΩ load resistance. The effectiveness against the velocity-damped resonant-generator (VDRG) limit was 2.5%. The electrostatic forces of the actual device with DC bias, which simulates charged electret with monopolar and bipolar were experimentally and numerically verified. We estimated the electrostatic force by measuring the vibration amplitude versus applied acceleration of the electret mass. As a result, we investigated the bipolar charged device can reduce the effect of electrostatic force as low as no bias condition. The numerical model of the energy harvester considering the electrostatic force by FEM static analysis was also established. The comparison between the numerical model and the measurement results showed a similar inclination

  20. Peculiarities of unusual electret state in porous zeolite microstructure

    Science.gov (United States)

    Bunyatova, U.; Orbukh, V. I.; Eyvazova, G. M.; Lebedeva, N. N.; Agamaliev, Z. A.; Koçum, I. C.; Ozer, M.; Salamov, B. G.

    2017-11-01

    This study explores, for the first time to our knowledge, the influence of electret state on the dielectric parameters of porous zeolite of frequencies up to 106 Hz, at room temperature and normal atmospheric pressure. The I-V characteristics with unusual hysteresis loop in the wide pressure range were measured on zeolite plates having three different material characteristics: A) plate, cut out from a monoblock natural zeolite; B) plate, modified by silver ions, and C) plate containing silver nanoparticles. Zeolite samples were exposed to an electric field (Ep = 2 kV cm-1) in an air atmosphere for 240 min. It is established, that the stability of electret state and value of the dielectric response ε‧ and ε″ for clinoptilolite Ag nanoparticles containing plates changed under influence of DC electric field. During some time the dielectric response is restored and observed unique phenomenon indicates on the electret behavior of clinoptilolite samples. These changes are observed within a few days consequently, there is long-term dynamics of the dielectric response changes. This interpretation is based on the assumption that due influence of the dc electric field part of the silver atoms in nanoparticles decays into ions and electrons.

  1. High-performance gap-closing vibrational energy harvesting using electret-polarized dielectric oscillators

    Science.gov (United States)

    Feng, Yue; Yu, Zejie; Han, Yanhui

    2018-01-01

    In conventional gap-closing electret-biased electrostatic energy harvesting (EEEH) schemes, electrets with a very low ratio of electret thickness to permittivity are in great demand to allow the attainment of high power output. However, in practice, pursuing such a low ratio introduces unwanted burdens on the electret stability and therefore the reliability of the EEEH devices. In this paper, we propose a dielectric-oscillator-based electrostatic EH (DEEH) scheme as an alternative approach to harvesting electret-biased electrostatic energy. This approach permits the fabrication of an electret-free closed EH circuit. The DEEH architecture directly collects the electrical energy exclusively through the oscillating dielectric body and thus completely circumvents the restrictions imposed by the electret parameters (thickness and permittivity) on power generation. Significantly, without considering the electret thickness and permittivity, both theoretical analysis and experiments have verified the effectiveness of this DEEH strategy, and a high figure of merit (on the order of 10-8 mW cm-2 V-2 Hz-1) was achieved for low-frequency movements.

  2. Preamplifier with ultra low frequency cutoff for infrasonic condenser microphone

    DEFF Research Database (Denmark)

    Kinnerup, Rasmus Trock; Marbjerg, Kresten; Rasmussen, Per

    2012-01-01

    B. Being able to measure down to ultra low frequencies in the infrasonic frequency range will aid actors in the debate on wind turbine noise. Sonic booms from supersonic flights include frequencies down to 10 mHz and the preamplifier proposed in this paper will aid scientists trying to modify the N......-shaped shock wave at high level which prohibits flights in land zones....

  3. Electret-based Unsteady Thermal Energy Harvester using Potassium Tantalate Niobate Crystal

    Science.gov (United States)

    Xie, Hong; Morimoto, Kenichi; Suzuki, Yuji

    2016-11-01

    An electret-based unsteady thermal energy harvester is proposed using potassium tantalate niobate (KTa1-xNbxO3, KTN) as a dielectric for the capacitor. By connecting in series the capacitor and an electret serving as a permanent voltage source, the capacitance change with temperature fluctuations alters the amount of induced charges thereby produces the external current. By using KTN having extremely-large temperature coefficient of permittivity together with the CYTOP electret, the output power of 572 nJ has been obtained from one heating cycle, which corresponds to 20 times higher output power than the previous result with BaTiO3.

  4. Physical aspects of electron emission spectra shape for ferroelectrics-electrets

    International Nuclear Information System (INIS)

    Kolesnikov, V.V.; Kozakov, A.T.

    2002-01-01

    One introduces a theoretical approach establishing a link between the peculiarities of spectrum of electron emission from ferroelectrics-electrets and the behavior of potential at a specimen surface. From these points of view one analyzes physical nature of the key peculiarities in the experimental spectra. One points out strong effect of electret charge relaxation on their shape due to bifurcation (branching) of peculiarities in a spectrum. A complex shape of spectrum of electron emission from ferroelectrics-electrets results from peculiarities of distribution of electrical field and polarization along their surface [ru

  5. Micro-fabricated Liquid Encapsulated Energy Harvester with Polymer Barrier Layer as Liquid Electret Interface

    International Nuclear Information System (INIS)

    Bu, L; Xu, H Y; Xu, B J; Song, L

    2014-01-01

    This paper addresses the electret discharge issue for liquid based electret energy harvesters. An interface structure of PDMS/PTFE polymer barrier layer between liquid and electrets is introduced, achieving 75% charge retain rate over 100h, compared with 0% without the proposed layer over 100h. Further, the PDMS/PTFE layer is introduced into liquid encapsulated energy harvester (LEEH) and is compatible with micro-fabrication process. The retain rate of device voltage is about 47%∼65% over 100h. At 100h after corona charging, the device generates maximally 3.7V, 0.55μW @1Hz rotation

  6. The acoustic center of laboratory standard microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2006-01-01

    An experimental procedure is described for obtaining the effective acoustic distance between pairs of microphones coupled by a free field, leading to the determination of the position of the acoustic center of the microphones. The procedure, which is based on measuring the modulus of the electric...

  7. Ferroelectric Dipole Electrets Prepared from Soft and Hard PZT Ceramics in Electrostatic Vibration Energy Harvesters

    International Nuclear Information System (INIS)

    Asanuma, H; Oguchi, H; Hara, M; Kuwano, H

    2013-01-01

    Aiming at longer stability of surface potential, we propose a ferroelectric dipole electret (FDE) prepared from hard ferroelectric material. We compared output power of electrostatic vibration energy harvester and surface potential stability between FDEs prepared from soft and hard PZT ceramics, as well as a CYTOP polymer electret. The hard FDE showed a seven-fold increase in output power over the soft FDE and nine-fold increase over the CYTOP polymer electret. The hard FDE also showed longer stability of surface potential than that of the soft FDE, whereas the stability of the hard FDE was not yet comparable to that of CYTOP polymer electret. A FDE prepared from harder PZT ceramic (with higher coercive electric field and Curie temperature) may provide more stability in surface potential

  8. Enhanced electromechanical performance of cellular polypropylene electrets charged at a high temperature

    International Nuclear Information System (INIS)

    Zhang, J-W; Lebrun, L; Guiffard, B; Belouadah, R; Guyomar, D; Garbuio, L; Cottinet, P-J; Liu, Q

    2011-01-01

    In order to enhance the electromechanical performance of polypropylene (PP) electrets, cellular PP electrets were heated during corona poling at a high temperature in order to accelerate its chemical structure change and increase the quantity of formed dipole within the electrets. We investigated the behaviour of surface potential decay after corona poling, and the results showed that corona poling at a high temperature can improve the charge retention of commercially used cellular PP. The results of thermally stimulated depolarization current indicated the different localized states of the electric charges in cellular PP electrets after corona poling. Then, enhanced electromechanical ability was measured by a deformation measurement system and large strain (about 5%) under a moderate applied electric field intensity (30 MV m -1 ) was obtained.

  9. Enhanced electromechanical performance of cellular polypropylene electrets charged at a high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J-W; Lebrun, L; Guiffard, B; Belouadah, R; Guyomar, D; Garbuio, L; Cottinet, P-J; Liu, Q, E-mail: jiawei.zhang@insa-lyon.fr [Laboratoire de Genie Electrique et Ferroelectricite, LGEF EA 682, INSA-Lyon, Universite de Lyon, 8 rue de la Physique, Bat. Gustave Ferrie, F-69621, Villeurbanne (France)

    2011-10-19

    In order to enhance the electromechanical performance of polypropylene (PP) electrets, cellular PP electrets were heated during corona poling at a high temperature in order to accelerate its chemical structure change and increase the quantity of formed dipole within the electrets. We investigated the behaviour of surface potential decay after corona poling, and the results showed that corona poling at a high temperature can improve the charge retention of commercially used cellular PP. The results of thermally stimulated depolarization current indicated the different localized states of the electric charges in cellular PP electrets after corona poling. Then, enhanced electromechanical ability was measured by a deformation measurement system and large strain (about 5%) under a moderate applied electric field intensity (30 MV m{sup -1}) was obtained.

  10. Non-volatile organic transistor memory devices using the poly(4-vinylpyridine)-based supramolecular electrets.

    Science.gov (United States)

    Chou, Y-H; Chiu, Y-C; Lee, W-Y; Chen, W-C

    2015-02-14

    Supramolecular electrets consisting of poly(4-vinylpyridine) (P4VP) and conjugated molecules of phenol, 2-naphthol and 2-hydroxyanthracene were investigated for non-volatile transistor memory applications. The memory windows of these supramolecular electret devices were significantly enhanced upon increasing the π-conjugation size of the molecule. A high ON/OFF current ratio of more than 10(7) over 10(4) s was achieved on the supramolecule based memory devices.

  11. Sodium immersible high temperature microphone design description

    International Nuclear Information System (INIS)

    Gavin, A.P.; Anderson, T.T.; Janicek, J.J.

    1975-02-01

    Argonne National Laboratory has developed a rugged high-temperature (HT) microphone for use as a sodium-immersed acoustic monitor in Liquid Metal Fast Breeder Reactors (LMFBRs). Microphones of this design have been extensively tested in room temperature water, in air up to 1200 0 F, and in sodium up to 1200 0 F. They have been successfully installed and employed as acoustic monitors in several operating liquid metal systems. The design, construction sequence, calibration, and testing of these microphones are described. 6 references. (U.S.)

  12. Mapping Speech Spectra from Throat Microphone to Close-Speaking Microphone: A Neural Network Approach

    Directory of Open Access Journals (Sweden)

    B. Yegnanarayana

    2007-01-01

    Full Text Available Speech recorded from a throat microphone is robust to the surrounding noise, but sounds unnatural unlike the speech recorded from a close-speaking microphone. This paper addresses the issue of improving the perceptual quality of the throat microphone speech by mapping the speech spectra from the throat microphone to the close-speaking microphone. A neural network model is used to capture the speaker-dependent functional relationship between the feature vectors (cepstral coefficients of the two speech signals. A method is proposed to ensure the stability of the all-pole synthesis filter. Objective evaluations indicate the effectiveness of the proposed mapping scheme. The advantage of this method is that the model gives a smooth estimate of the spectra of the close-speaking microphone speech. No distortions are perceived in the reconstructed speech. This mapping technique is also used for bandwidth extension of telephone speech.

  13. Mic it! microphones, microphone techniques, and their impact on the final mix

    CERN Document Server

    Corbett, Ian

    2014-01-01

    Capture great sound in the first place, and spend less time ""fixing it in the mix"" with Ian Corbett's Mic It! Microphones, Microphone Techniques, and Their Impact on the Final Mix. With his expert guidance, you'll quickly understand essential audio concepts as they relate to microphones and mic techniques, and learn how to apply them to your recording situation. Whether you only ever buy one microphone, are equipping a studio on a budget, or have a vast selection of great mics to use, you'll learn to better use whatever tools you have. Mic It! gives you the background to design and discover

  14. Study and Design of Differential Microphone Arrays

    CERN Document Server

    Benesty, Jacob

    2013-01-01

    Microphone arrays have attracted a lot of interest over the last few decades since they have the potential to solve many important problems such as noise reduction/speech enhancement, source separation, dereverberation, spatial sound recording, and source localization/tracking, to name a few. However, the design and implementation of microphone arrays with beamforming algorithms is not a trivial task when it comes to processing broadband signals such as speech. Indeed, in most sensor arrangements, the beamformer tends to have a frequency-dependent response. One exception, perhaps, is the family of differential microphone arrays (DMAs) that have the promise to form frequency-independent responses. Moreover, they have the potential to attain high directional gains with small and compact apertures. As a result, this type of microphone arrays has drawn much research and development attention recently. This book is intended to provide a systematic study of DMAs from a signal processing perspective. The primary obj...

  15. Investigation of noise radiation from a swirl stabilized diffusion flame with an array of microphones

    International Nuclear Information System (INIS)

    Singh, A.V.; Yu, M.; Gupta, A.K.; Bryden, K.M.

    2013-01-01

    Highlights: • Acoustic spectral characteristics independent of equivalence ratio and flow velocity. • Combustion noise dependent on global equivalence ratio and flow velocity. • Increased global equivalence ratio decreased the frequency of peak. • Decay and growth coefficients largely independent of different flow conditions. • Acoustic radiation coherent up to 1.5 kHz for spatially separated microphones. - Abstract: Next generation of combustors are expected to provide significant improvement on efficiency and reduced pollutants emission. In such combustors, the challenges of local flow, pressure, chemical composition and thermal signatures as well as their interactions will require detailed investigation for seeking optimum performance. Sensor networks with a large number of sensors will be employed in future smart combustors, which will allow one to obtain fast and comprehensive information on the various ongoing processes within the system. In this paper sensor networks with specific focus on an array of homogeneous microphones are used examine the spectral characteristics of combustion noise from a non-premixed combustor. A non-premixed double concentric swirl-flame burner was used. Noise spectra were determined experimentally for the non-premixed swirl flame at various fuel–air ratios using an array of homogeneous condenser microphones. Multiple microphones positioned at discrete locations around the turbulent diffusion flame, provided an understanding of the total sound power and their spectral characteristics. The growth and decay coefficients of total sound power were investigated at different test conditions. The signal coherence between different microphone pairs was also carried out to determine the acoustic behavior of a swirl stabilized turbulent diffusion flame. The localization of acoustic sources from the multiple microphones was examined using the noise spectra. The results revealed that integration of multiple sensors in combustors

  16. Growth and decay of surface charges in grafts of Teflon in electrets states

    International Nuclear Information System (INIS)

    Spinelli, I.M.M.

    1971-01-01

    The greatest problem founded in a cardiovascular implant is the thrombus formation. Teflon grafts were used in electret state for prothesis in vena cava of dogs. To put these grafts in an electret state a corona discharge in air was used and homocharge was formed predominantly. To measure the formed surface charge the oscillating capacitor technique was used. In the electret state the grafts have showed an initial density of charge of 10- 8 C/cm 2 and the charge decay and time decay of the samples were measured under many conditions. We found two activation energies, E 2 =0.17 e V and E 3 =1.12 e V, due to rapid and slow decay, respectively. The charged grafts were sterilized with ethilene gas oxide and this process apparently did not influence the charges

  17. Electret ionization chamber: a new method for detection and dosimetry of thermal neutrons

    International Nuclear Information System (INIS)

    Ghilardi, A.J.P.

    1988-01-01

    An electret ionization chamber with boron coated walls is presented as a new method for detecting thermal neutrons. The efficiency of electret ionization chambers with different wall materials for the external electrode was inferred from the results. Detection of slow neutrons with discrimination against the detection of γ-rays and energetic neutrons was shown to depend on the selection of these materials. The charge stability over a long period of time and the charge decay owing to natural radiation were also studied. Numerical analysis was developed by the use of a micro-computer PC-XT. Both the experimental and numerical results show that the sensitivity of the electret ionization chamber for detection of thermal neutrons is comparable with that of the BF 3 ionization chamber and that new technologies for deposition of the boron layer will produce higher efficiency detectors. (author). 102 refs, 32 fig, 10 tabs

  18. Electrets in soft materials: nonlinearity, size effects, and giant electromechanical coupling.

    Science.gov (United States)

    Deng, Qian; Liu, Liping; Sharma, Pradeep

    2014-07-01

    Development of soft electromechanical materials is critical for several tantalizing applications such as soft robots and stretchable electronics, among others. Soft nonpiezoelectric materials can be coaxed to behave like piezoelectrics by merely embedding charges and dipoles in their interior and assuring some elastic heterogeneity. Such so-called electret materials have been experimentally shown to exhibit very large electromechanical coupling. In this work, we derive rigorous nonlinear expressions that relate effective electromechanical coupling to the creation of electret materials. In contrast to the existing models, we are able to both qualitatively and quantitatively capture the known experimental results on the nonlinear response of electret materials. Furthermore, we show that the presence of another form of electromechanical coupling, flexoelectricity, leads to size effects that dramatically alter the electromechanical response at submicron feature sizes. One of our key conclusions is that nonlinear deformation (prevalent in soft materials) significantly enhances the flexoelectric response and hence the aforementioned size effects.

  19. Electrets in soft materials: Nonlinearity, size effects, and giant electromechanical coupling

    Science.gov (United States)

    Deng, Qian; Liu, Liping; Sharma, Pradeep

    2014-07-01

    Development of soft electromechanical materials is critical for several tantalizing applications such as soft robots and stretchable electronics, among others. Soft nonpiezoelectric materials can be coaxed to behave like piezoelectrics by merely embedding charges and dipoles in their interior and assuring some elastic heterogeneity. Such so-called electret materials have been experimentally shown to exhibit very large electromechanical coupling. In this work, we derive rigorous nonlinear expressions that relate effective electromechanical coupling to the creation of electret materials. In contrast to the existing models, we are able to both qualitatively and quantitatively capture the known experimental results on the nonlinear response of electret materials. Furthermore, we show that the presence of another form of electromechanical coupling, flexoelectricity, leads to size effects that dramatically alter the electromechanical response at submicron feature sizes. One of our key conclusions is that nonlinear deformation (prevalent in soft materials) significantly enhances the flexoelectric response and hence the aforementioned size effects.

  20. Design of circular differential microphone arrays

    CERN Document Server

    Benesty, Jacob; Cohen, Israel

    2015-01-01

    Recently, we proposed a completely novel and efficient way to design differential beamforming algorithms for linear microphone arrays. Thanks to this very flexible approach, any order of differential arrays can be designed. Moreover, they can be made robust against white noise amplification, which is the main inconvenience in these types of arrays. The other well-known problem with linear arrays is that electronic steering is not really feasible.  In this book, we extend all these fundamental ideas to circular microphone arrays and show that we can design small and compact differential arrays of any order that can be electronically steered in many different directions and offer a good degree of control of the white noise amplification problem, high directional gain, and frequency-independent response. We also present a number of practical examples, demonstrating that differential beamforming with circular microphone arrays is likely one of the best candidates for applications involving speech enhancement (i....

  1. Fiberoptic microphone using a polymeric cavity

    Science.gov (United States)

    Wang, Wei-Chih; Soetanto, William; Gu, Kebin

    2011-04-01

    The fabrication and experimental investigation of a fiberoptic microphone is described. The sensing element is a silicon diaphragm with gold thin film coating that is positioned inside a silicone rubber mold at the end of a single mode optical fiber. Thus, a Fabry-Perot interferometer is formed between the inner fiber and the diaphragm. An acoustic pressure change is detected by using the developed microphone. The polymeric cavity and silicon diaphragm-based system exhibits excellent physicochemical properties with a small, simple, low cost, and lightweight design. The system is also electromagnetic interference / radio frequency interference immunity due to the use of fiberoptics.

  2. Two-microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    2006-01-01

    In this demonstration we show the separation of 3-7 mixed speech sources based on information from two microphones. Separation with background noise is demonstrated too. The algorithms are described in 1] Michael Syskind Pedersen, DeLiang Wang, Jan Larsen and Ulrik Kjems: "Two-microphone Separation...... of Speech Mixtures," 2006, submited for journal publication. See also, [2] Michael Syskind Pedersen, DeLiang Wang, Jan Larsen and Ulrik Kjems: "Overcomplete Blind Source Separation by Combining ICA and Binary Time-Frequency Masking," in proceedings of IEEE International workshop on Machine Learning...

  3. 77 FR 64446 - Wireless Microphones Proceeding

    Science.gov (United States)

    2012-10-22

    ... to balance the needs of potential new classes of wireless microphone licensees with those of other... undercut that balance by significantly reducing the amount of spectrum available for other uses, such as by..., a space capacity-rated for 3,000 people; for sports venues, a minimum of 10,000 seats for indoors...

  4. Locating noise sources with a microphone array

    International Nuclear Information System (INIS)

    Bale, A.; Johnson, D.

    2010-01-01

    Noise pollution is one of the contributors to the public opposition of wind farms. Most of the noise produced by turbines is caused by the aerodynamic interactions between the turbine blades and the surrounding air. This poster presentation discussed a series of aeroacoustic tests conducted to account for the different in vortical structures caused by the rotation of the blades. Microphone arrays were used measure and locate the source of noise. A beam forming technique was used to measure the noise using an algorithm that identified a scanning grid on a plane where the source was thought to be located. It delayed each microphone's signal by the length of time required for the sound to travel from the scan position to each microphone, and accounted for the amplitudes according to the distance from the scan position to each microphone. Demonstration test cases were conducted using piezo buzzers attached to aluminum bars and mounted to the shaft of a DC motor that produced a rotational diameter of 0.95 meter. The buzzers were placed 1 meter from the array. Multiple sound sources at the same frequency were identified, and the moving sources were accurately measured and located. tabs., figs.

  5. Compressive sensing with a spherical microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Xenaki, Angeliki

    2016-01-01

    A wave expansion method is proposed in this work, based on measurements with a spherical microphone array, and formulated in the framework provided by Compressive Sensing. The method promotes sparse solutions via ‘1-norm minimization, so that the measured data are represented by few basis functions...

  6. Two-microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    2006-01-01

    Matlab source code for underdetermined separation of instaneous speech mixtures. The algorithm is described in [1] Michael Syskind Pedersen, DeLiang Wang, Jan Larsen and Ulrik Kjems: ''Two-microphone Separation of Speech Mixtures,'' 2006, submitted for journal publoication. See also, [2] Michael...

  7. Filtering microphonics in dark matter germanium experiments

    International Nuclear Information System (INIS)

    Morales, J.; Garcia, E.; Ortiz de Solorzano, A.; Morales, A.; Nunz-Lagos, R.; Puimedon, J.; Saenz, C.; Villar, J.A.

    1992-01-01

    A technique for reducing the microphonic noise in a germanium spectrometer used in dark matter particles searches is described. Filtered energy spectra, corresponding to 48.5 kg day of data in a running experiment in the Canfranc tunnel are presented. Improvements of this filtering procedure with respect to the method of rejecting those events not distributed evenly in time are also discussed. (orig.)

  8. APPLICATION OF MICROPHONE ARRAYS FOR DISTANT SPEECH CAPTURE

    Directory of Open Access Journals (Sweden)

    M. B. Stolbov

    2015-07-01

    Full Text Available Application of microphone arrays and beamforming techniques for speech information collection has significant advantages compared to systems operating with a single microphone. This paper presents a brief overview of microphone array systems for collecting distant speech information. The paper is based on an analysis of publications on the use of microphone arrays for speech information collection tasks, as well as on the author’s experience in the development and practical application of planar microphone arrays. The paper describes the main stages of the development of systems for remote capture of audio information. It provides a review of the main applications of microphone arrays, the basic types of microphone arrays and their features. The bulk of the paper deals with planar microphone arrays. We analyze the work of microphone arrays in different acoustic environments. The paper contains the basic equations for calculating the parameters of equidistant planar microphone arrays. Some methods of designing non-equidistant arrays are also mentioned (a list of references is included. We also provide a list of basic digital signal processing algorithms for planar microphone arrays, as well as a list of references on processing algorithms in the frequency domain. The paper includes a list of foreign companies offering systems based on microphone arrays for a wide range of tasks associated with the processing of speech and audio signals. We describe some state-of-the-art speech information collection systems based on microphone arrays. Some promising directions for the development of speech information collection systems using microphone arrays are described in conclusion. The material of the review is usable in designing of microphone arrays for specific practical applications.

  9. A flexible electrostatic kinetic energy harvester based on electret films of electrospun nanofibers

    Science.gov (United States)

    Lu, Y.; Capo-Chichi, M.; Leprince-Wang, Y.; Basset, P.

    2018-01-01

    This paper reports a paper-based electrostatic kinetic energy harvester (e-KEH) implementing multilayered electret films based on electrospun nanofibrous material. It is the first time that a fully flexible electret-based e-KEH is reported. The proposed electret, PVDF-PTFD nanofibrous covered by Parylene C, has a faster stabilization of surface potential than a planar thin film of Parylene C, and a higher stability of charge storage. With a maximum force of 0.5 N and a 3-layer electret, the device capacitance increases from 25 to 100 pF during a pressing operation. Working with the optimal resistive load of 16 MΩ, the device pressed manually delivers a peak instantaneous power up to 45.6 μW and an average energy of 54 nJ/stroke, corresponding to a peak instantaneous power density of 7.3 μW cm‑2 and an average energy density of 8.6 nJ cm‑2/stroke. Within 450 manual strokes, a 10 nF capacitor is charged up to 8.5 V by the prototype through a full-wave diode bridge. On a 1 μF capacitor, the energy delivery of 9.9 nJ/stroke has been obtained with a 10 Hz pressing movement excited by a vibrator with a maximum force of 0.5 N.

  10. Design, modeling, fabrication and characterization of an electret-based MEMS electrostatic energy harvester

    NARCIS (Netherlands)

    Altena, G.; Hohlfeld, D.; Elfrink, R.; Goedbloed, M.H.; Schaijk, R. van

    2011-01-01

    This paper reports on the design, modelling, fabrication and characterization of an electret-based MEMS electrostatic energy harvester with an elegant and robust process flow. The fabrication is based on a SOI wafer with self-aligned electrodes of the variable capacitor. The output current of the

  11. Thickness effects of electret and polymer for energy harvesting: Case of CYTOP- CTLM and polyurethane

    Science.gov (United States)

    Belhora, Fouad; Guyomar, Daniel; Mazroui, M'Hammed; Hajjaji, Abdelowahed; Boughaleb, Yahia

    2015-02-01

    The authors aimed to investigate the electrostrictive polymers for energy harvesting. These particular materials have demonstrated a great ability to convert mechanical energy into electrical energy and vice versa. This energy conversion has been exploited in an extensive range of applications, including sensors and actuators. On the other hand, the reason for using electrets in the present work was to produce the static electric field required to capture energy through electrostrictive polymers and hence to avoid the problem of high voltage power. For a good μ-generators performance the electromechanical parameters have to be optimized. Experimental results show the possibility of improving harvesting energy without power supply, by using hybridization of electrets and electrostrictive materials, which is very promising for future applications. Moreover, in order to obtain a maximum of harvested power one should choose a minimum of the thickness of the electrets and a maximum of thickness of polymer. The measured results are analyzed and compared with the theoretical model and they are consistent. These results shed light on the hybridization of electrostrictive polymer with electrets, and are useful for improving the harvesting energy.

  12. Continuous measurement of the radon concentration in water using electret ion chamber method

    International Nuclear Information System (INIS)

    Dua, S.K.; Hopke, P.K.

    1992-10-01

    A radon concentration of 300 pCi/L has been proposed by the US Environmental Protection Agency as a limit for radon dissolved in municipal drinking water supplies. There is therefore a need for a continuous monitor to insure that the daily average concentration does not exceed this limit. In order to calibrate the system, varying concentrations of radon in water have been generated by bubbling radon laden air through a dynamic flowthrough water system. The value of steady state concentration of radon in water from this system depends on the concentration of radon in air, the air bubbling rate, and the water flow rate. The measurement system has been designed and tested using a 1 L volume electret ion chamber to determine the radon in water. In this dynamic method, water flows directly through the electret ion chamber. Radon is released to the air and measured with the electret. A flow of air is maintained through the chamber to prevent the build-up of high radon concentrations and too rapid discharge of the electret. It was found that the system worked well when the air flow was induced by the application of suction. The concentration in the water was calculated from the measured concentration in air and water and air flow rates. Preliminary results suggest that the method has sufficient sensitivity to measure concentrations of radon in water with acceptable accuracy and precision

  13. MEMS microphone with a micro Helmholtz resonator

    International Nuclear Information System (INIS)

    Takahashi, Hidetoshi; Matsumoto, Kiyoshi; Shimoyama, Isao; Suzuki, Akira; Iwase, Eiji

    2012-01-01

    This paper reports on the development of a micro electro mechanical system microphone consisting of a piezoresistive cantilever and a micro HR (Helmholtz resonator) for use as an ultrasonic proximity sensor. The resonance frequency of the HR was designed to be equal to that of the cantilever. Therefore, the HR increases the sensitivity of the microphone to ultrasonic waves. The dimensions of the fabricated HR and the cantilever are 1.2 mm × 1.2 mm × 0.6 mm and 130 µm × 40 µm × 0.3 µm, respectively. At a resonance frequency of 22.6 kHz, the cantilever with the HR detected ultrasonic waves with 14 times greater sensitivity than that of the cantilever without the HR. We demonstrated that the fabricated sensor is capable of measuring distances between 0.5 and 6.0 m. (paper)

  14. Hydrogel microphones for stealthy underwater listening

    Science.gov (United States)

    Gao, Yang; Song, Jingfeng; Li, Shumin; Elowsky, Christian; Zhou, You; Ducharme, Stephen; Chen, Yong Mei; Zhou, Qin; Tan, Li

    2016-08-01

    Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or cavity-based microphones that respond to stimuli by deforming the device in thickness directions, this hydrogel device responds with a transient modulation of electric double layers, resulting in an extraordinary sensitivity (217 nF kPa-1 or 24 μC N-1 at a bias of 1.0 V) without using any signal amplification tools.

  15. Water Condensation

    DEFF Research Database (Denmark)

    Jensen, Kasper Risgaard; Fojan, Peter; Jensen, Rasmus Lund

    2014-01-01

    The condensation of water is a phenomenon occurring in multiple situations in everyday life, e.g., when fog is formed or when dew forms on the grass or on windows. This means that this phenomenon plays an important role within the different fields of science including meteorology, building physics......, and chemistry. In this review we address condensation models and simulations with the main focus on heterogeneous condensation of water. The condensation process is, at first, described from a thermodynamic viewpoint where the nucleation step is described by the classical nucleation theory. Further, we address...

  16. Proximity sensing of electrostatic induction electret nanoparticles device using separation electrode

    Directory of Open Access Journals (Sweden)

    Jianxiong Zhu

    2017-04-01

    Full Text Available We reported a two dimensional self-powered proximity sensor based on nanoparticles polytetrafluoroethylene (PTFE electrostatic induction electret using separation electrode. The structural pattern was carefully designed for identifying the specific position on the horizontal plane. When the separation electrode is motioned above the sensor, the induced charges on electrodes will change based on the coupling effect of the electret film. Experiment results showed that the proximity sensor works well with the velocity 0.05 m/s. We also found that the prototype have a good stability even with a huge uncontrolled perturbation on the Y direction. Our work could be a significant step forward in self-powered proximity sensing technology, with a wide range of potential applications in touchpad, robotics, and safety-monitoring device.

  17. Relationship of Adhesive, Contact and Electret Properties of PTFE Modified by DC Discharge

    Science.gov (United States)

    Yablokov, M.; Piskarev, M.; Gilman, A.; Kechek'yan, A.; Kuznetsov, A.

    2018-02-01

    The relationship between the contact, adhesive and electret properties of PTFE films modified by direct current glow discharge has been studied. The film samples of 40 μm thickness were placed at the anode and cathode and treated in the air as a working gas. The contact properties of polymer surface were characterized by the values of deionized water contact angle. The peel strength was determined using T-peel test for the Scotch®810/PTFE film contact. The electret potential was measured by the compensation technique using dynamic capacitor, and from the measured potential value the effective surface charge density was calculated. It has been found that there is an undoubted correlation between the change in the value of water contact angle, the peel strength of the DC discharge-treated film, and the magnitude of the effective surface charge.

  18. Interrelation of electret properties of polyethylene foam from the method of cross-linking

    Science.gov (United States)

    Gilmanov, I. R.; Galikhanov, M. F.; Gilmanova, A. R.

    2017-09-01

    The electret properties of chemically cross-linked polyethylene foam and physically cross-linked polyethylene foam have been studied. It has been shown that chemically cross-linked polyethylene foam has higher surface potential, effective surface charge density and electric field strength compared to physically bonded polyethylene foam. This is due to the presence of molecules and fragments of dicumyl peroxide, which can play the role of traps for injection charge carriers, a greater degree of cross-linking and with the oxidation of polyethylene, which occurs during irradiation during physical cross-linking. When the foam is deformed, its electret properties are reduced, and when the volume is relaxed, they are restored. This is due to the partial mutual compensation of homo- and heterocharge during compression and the return of the structure of the gas-filled polymer to its former position when the load is removed.

  19. An acoustical array combining microphones and piezoelectric devices.

    Science.gov (United States)

    Matsumoto, Mitsuharu; Hashimoto, Shuji

    2008-04-01

    This paper describes an acoustical array combining microphones and piezoelectric devices. Conventional microphone arrays have been widely utilized to realize noise reduction, sound separation and direction of arrival estimation system. However, when a conventional microphone array is mounted on a real system, such as a machine, vehicle or robot, the microphones are set extremely close to the system's actual body. In such cases, the noise from the system itself, such as motors, gears, and engines, namely internal noise, often becomes a troublesome problem. It is difficult to reduce internal noise utilizing a conventional microphone array because internal noise sources are extremely close to the microphones. As internal noise is not always stationary, statistically independent or sparse, most useful blind source separation approaches, such as independent component analysis and the sparseness approach, cannot be employed. Our aim is to reduce internal noise utilizing microphones and piezoelectric devices attached to the internal noise source. In this paper, a general description of the acoustical array is formulated and the characteristic features of microphones and piezoelectric devices in an acoustical array are given. An acoustical array combining microphones and piezoelectric devices is also described with some experimental results.

  20. Comparison of binaural microphones for externalization of sounds

    DEFF Research Database (Denmark)

    Cubick, Jens; Sánchez Rodríguez, C.; Song, Wookeun

    2015-01-01

    or with microphones placed inside the ear canals of a person. In this study, binaural room impulse responses (BRIRs) were measured with several commercially available binaural microphones, both placed inside the listeners’ ears (individual BRIR) and on a head and torso simulator (generic BRIR). The degree...... of externalization of speech and noise stimuli was tested in a listening experiment with a multi-stimulus test. No influence was found for the stimulus signal, but the externalization scores were found to be lower for 0◦ incidence. With all microphones, relatively high externalization scores were achieved......, and for all but one microphone, individual BRIRs resulted in slightly better externalization than generic ones....

  1. Promotion of the transdermal delivery of protein drugs by N-trimethyl chitosan nanoparticles combined with polypropylene electret

    Directory of Open Access Journals (Sweden)

    Tu Y

    2016-10-01

    Full Text Available Ye Tu,1,2,* Xinxia Wang,3,* Ying Lu,2,* He Zhang,2 Yuan Yu,2 Yan Chen,2 Junjie Liu,2 Zhiguo Sun,2 Lili Cui,4 Jing Gao,2 Yanqiang Zhong2 1Department of Medical Affairs, East Hospital, Tongji University School of Medicine, 2Department of Pharmaceutical Science, School of Pharmacy, Second Military Medical University, 3Department of Pharmacy, East Hospital of Hepatobiliary Surgery, 4Department of Inorganic Chemistry, School of Pharmacy, Second Military Medical University, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: We recently reported that electret, which was prepared by a corona charging system with polypropylene film, could enhance the transdermal delivery of several drugs of low molecular weight. The aim of this study was to investigate whether electret could enhance the transdermal delivery of protein drugs by N-trimethyl chitosan nanoparticles (TMC NPs prepared by an ionic gelation method. A series of experiments were performed, including in vitro skin permeation assays and anti-inflammatory effects, to evaluate the transdermal delivery of protein drugs by TMC NPs in the presence of electret. The results showed that in the presence of electret, the transdermal delivery of protein drugs in TMC NPs was significantly enhanced, as demonstrated by in vitro permeation studies and confocal laser scanning microscopy. Notably, superoxide dismutase-loaded TMC NPs combined with electret exhibited the best inhibitory effect on the edema of the mouse ear. TMC NPs combined with electret represent a novel platform for the transdermal delivery of protein drugs. Keywords: N-trimethyl chitosan nanoparticles, electret, transdermal delivery, protein drugs 

  2. New approach to improve the energy density of hybrid electret-dielectric elastomer generators

    Science.gov (United States)

    Lagomarsini, Clara; Jean-Mistral, Claire; Monfray, Stephane; Sylvestre, Alain

    2017-04-01

    Harvesting human kinetic energy to produce electricity is an attractive alternative to batteries for applications in wearable electronic devices and smart textile. Dielectric elastomers generators (DEGs) represent one of the most promising technologies for these applications. Nevertheless, one of the main disadvantages of these structures is the need of an external polarization source to perform the energetic cycle. In the present work, a hybrid electret-dielectric elastomer generator in DEG mode is presented. In this configuration, the electret material is used as polarization source of a classical DEG, i.e. an electrostatic generator based on electrical capacitance variation. The electrical energy output in this mode (1.06mJ.g-1) could be higher than the one obtained using a classical electret mode (0.55mJ.g-1), i.e. charges recombination. In this paper, the operation principle of the hybrid generator will be fully described and the design rules for the realization of the prototype will be presented. The experimental data obtained from the prototype will be compared to the results of FEM simulations.

  3. Steam condenser

    International Nuclear Information System (INIS)

    Masuda, Fujio

    1980-01-01

    Purpose: To enable safe steam condensation by providing steam condensation blades at the end of a pipe. Constitution: When high temperature high pressure steam flows into a vent pipe having an opening under water in a pool or an exhaust pipe or the like for a main steam eacape safety valve, non-condensable gas filled beforehand in the steam exhaust pipe is compressed, and discharged into the water in the pool. The non-condensable gas thus discharged from the steam exhaust pipe is introduced into the interior of the hollow steam condensing blades, is then suitably expanded, and thereafter exhausted from a number of exhaust holes into the water in the pool. In this manner, the non-condensable gas thus discharged is not directly introduced into the water in the pool, but is suitable expanded in the space of the steam condensing blades to suppress extreme over-compression and over-expansion of the gas so as to prevent unstable pressure vibration. (Yoshihara, H.)

  4. Evaluation of Performance With an Adaptive Digital Remote Microphone System and a Digital Remote Microphone Audio-Streaming Accessory System.

    Science.gov (United States)

    Wolfe, Jace; Duke, Mila Morais; Schafer, Erin; Jones, Christine; Mülder, Hans E; John, Andrew; Hudson, Mary

    2015-09-01

    One purpose of this study was to evaluate the improvement in speech recognition obtained with use of 2 different remote microphone technologies. Another purpose of this study was to determine whether a battery of audiometric measures could predict benefit from use of these technologies. Sentence recognition was evaluated while 17 adults used each of 2 different hearing aids. Performance was evaluated with and without 2 different remote microphone systems. A variety of audiologic measures were administered to determine whether prefitting assessment may predict benefit from remote microphone technology. Use of both remote microphone systems resulted in improvement in speech recognition in quiet and in noise. There were no differences in performance obtained with the 2 different remote microphone technologies in quiet and at low competing noise levels, but use of the digital adaptive remote microphone system provided better speech recognition in the presence of moderate- to high-level noise. The Listening in Spatialized Noise–Sentence Test Prescribed Gain Amplifier (Cameron & Dillon, 2010) measure served as a good predictor of benefit from remote microphone technology. Each remote microphone system improved sentence recognition in noise, but greater improvement was obtained with the digital adaptive system. The Listening in Spatialized Noise–Sentence Test Prescribed Gain Amplifier may serve as a good indicator of benefit from remote microphone technology.

  5. Advantages of directional hearing aid microphones related to room acoustics

    NARCIS (Netherlands)

    Leeuw, A. R.; Dreschler, W. A.

    1991-01-01

    In this study, two types of hearing aids were used. Both aids had the same frequency characteristics for frontal sound, but one employed an omnidirectional microphone and the other a directional microphone. The frequency characteristics of both hearing aids were measured for five azimuths on KEMAR

  6. Static pressure and temperature coefficients of working standard microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Cutanda Henriquez, Vicente; Torras Rosell, Antoni

    2016-01-01

    The sensitivity of measurement microphones is affected by changes in the environmental conditions, mainly temperature and static pressure. This rate of change has been the object of previous studies focused on Laboratory Standard microphones. The literature describes frequency dependent values fo...

  7. The ribbon microphone - an educational aid: use of a ribbon microphone to teach multi-discipline computer simulation skills

    CSIR Research Space (South Africa)

    Van Wyk, Marius

    2016-07-01

    Full Text Available on Advances in Computational Tools for Engineering Applications (ACTEA), 13-15 July 2016, Libanon The ribbon microphone — An educational aid: Use of a ribbon microphone to teach multi-discipline computer simulation skills Marius van Wyk ; Petrie Meyer...

  8. Evaluations of dielectric property and drug release profile of 5-FU patches based on plasma charged electrets

    Science.gov (United States)

    Wang, YUAN; Hejuan, LIANG; Ping, HUANG; Xiaoqiang, AN; Jian, JIANG; Lili, CUI

    2018-05-01

    In the present study, the electret 5-fluorouracil patch was developed, the effective surface potential, piezoelectric coefficient d 33, open-circuit thermally stimulated discharge (TSD) current spectra and shear adhesion of the patch were measured. The drug release profile of the patch was determined by using high performance liquid chromatography method. A stable potential difference which was positively dependent on the surface potential of the electret was generated on two sides of the patch. The measurements of d 33 coefficient, TSD current spectra and adhesion performance showed that the electrostatic field of the electret could cause polarization and cohesive strength decreasing of the matrix molecules, change the distribution and interaction of the drug molecules in patch, therefore to increase the release of drug from the transdermal patch.

  9. Virtual Microphones for Multichannel Audio Resynthesis

    Directory of Open Access Journals (Sweden)

    Athanasios Mouchtaris

    2003-09-01

    Full Text Available Multichannel audio offers significant advantages for music reproduction, including the ability to provide better localization and envelopment, as well as reduced imaging distortion. On the other hand, multichannel audio is a demanding media type in terms of transmission requirements. Often, bandwidth limitations prohibit transmission of multiple audio channels. In such cases, an alternative is to transmit only one or two reference channels and recreate the rest of the channels at the receiving end. Here, we propose a system capable of synthesizing the required signals from a smaller set of signals recorded in a particular venue. These synthesized “virtual” microphone signals can be used to produce multichannel recordings that accurately capture the acoustics of that venue. Applications of the proposed system include transmission of multichannel audio over the current Internet infrastructure and, as an extension of the methods proposed here, remastering existing monophonic and stereophonic recordings for multichannel rendering.

  10. Two-Microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Wang, DeLiang; Larsen, Jan

    2008-01-01

    Separation of speech mixtures, often referred to as the cocktail party problem, has been studied for decades. In many source separation tasks, the separation method is limited by the assumption of at least as many sensors as sources. Further, many methods require that the number of signals within...... combined, independent component analysis (ICA) and binary time–frequency (T–F) masking. By estimating binary masks from the outputs of an ICA algorithm, it is possible in an iterative way to extract basis speech signals from a convolutive mixture. The basis signals are afterwards improved by grouping...... similar signals. Using two microphones, we can separate, in principle, an arbitrary number of mixed speech signals. We show separation results for mixtures with as many as seven speech signals under instantaneous conditions. We also show that the proposed method is applicable to segregate speech signals...

  11. A high-performance micro electret power generator based on microball bearings

    International Nuclear Information System (INIS)

    Yang, Zhaohui; Wang, Jing; Zhang, Jinwen

    2011-01-01

    In this paper, a high-performance micro electret power generator fabricated by simple bulk micromachining technology is presented. It has microballs as movable bearings for harvesting changing low-frequency vibration energy from the environment. The silicon V-grooves where the microballs slide have very smooth (1 1 1) planes, and so the device is sensitive to very slight vibration and almost has no resonant frequency. A plasma-enhanced chemical vapour deposition SiO 2 /Si 3 N 4 double layer was used as the electret. The device was fabricated by simple micromachining technology suitable for mass production except for microball assembly. The influence of various frequencies and accelerations on the performance was studied in detail. The measurement results of this electret micro power generator show that the optimal load is proportional to the frequency, and inversely proportional to the acceleration. The peak-to-peak output charge and output power were 72 nC and 5.9 µW respectively at 20 Hz and 0.7 g with the optimal resistive load 626 kΩ. The work frequencies range from 100 Hz to a lower frequency (1 Hz). 112 nW can still be obtained in the minimum acceleration of 0.05 g at 10 Hz with the optimal resistive load, indicating that this device has high sensitivity. The possible application of our device in scavenging energy from low-frequency irregular movements, such as human motion, was proved by a primary experiment

  12. An electret-based energy harvesting device with a wafer-level fabrication process

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Wang, Fei; Hansen, Ole

    2013-01-01

    This paper presents a MEMS energy harvesting device which is able to generate power from two perpendicular ambient vibration directions. A CYTOP polymer is used both as the electret material for electrostatic transduction and as a bonding interface for low-temperature wafer bonding. The device...... is also discussed. With a final chip size of about 1 cm2, a power output of 32.5 nW is successfully harvested with an external load of 17 MΩ, when a harmonic vibration source with an RMS acceleration amplitude of 0.03 g (∼0.3 m s−2) and a resonant frequency of 179 Hz is applied. These results can...

  13. Air-spaced PDMS piezo-electret cantilevers for vibration energy harvesting

    Science.gov (United States)

    Kachroudi, A.; Basrour, S.; Rufer, L.; Jomni, F.

    2016-11-01

    This paper reports a design of a new prototype of air-spaced cantilevers made from a micro-structured PDMS piezo-electret material for accelerometer and energy harvesting applications. The test performed on these cantilevers in a sensor mode exhibits a stable sensitivity of 385 mV/g for a frequency ranging from 5 Hz to 200 Hz that encompass most macro-scale vibrations. In the energy harvesting mode, the cantilever generates a power of 103 nW with a load resistance of 217 MΩ.

  14. Study about the feasibility of using an electret dosemeter as a personal dosemeter

    International Nuclear Information System (INIS)

    Leitao, I.P.

    1983-01-01

    A feasibility study of the electret dosemeters as a personnel dosemeter was carried out. Preliminary tests were applied, in order to assess the dosemeter response to radiation, linearity, stability, reproductibility, direcional dependence and energy dependence in energy range from 33 to 1250 KeV. In general the results are in agreement with the recommendations of the Commision of the European Communities (CEC) for the use of this device as a personnel dosemeter with the exception of the energy dependence and the stability at medium term. (Author) [pt

  15. An investigation of methods for free-field comparison calibration of measurement microphones

    DEFF Research Database (Denmark)

    Barrera-Figueroa, Salvador; Moreno Pescador, Guillermo; Jacobsen, Finn

    2010-01-01

    Free-field comparison calibration of measurement microphones requires that a calibrated reference microphone and a test microphone are exposed to the same sound pressure in a free field. The output voltages of the microphones can be measured either sequentially or simultaneously. The sequential m...

  16. Localization of sound sources in a room with one microphone

    Science.gov (United States)

    Peić Tukuljac, Helena; Lissek, Hervé; Vandergheynst, Pierre

    2017-08-01

    Estimation of the location of sound sources is usually done using microphone arrays. Such settings provide an environment where we know the difference between the received signals among different microphones in the terms of phase or attenuation, which enables localization of the sound sources. In our solution we exploit the properties of the room transfer function in order to localize a sound source inside a room with only one microphone. The shape of the room and the position of the microphone are assumed to be known. The design guidelines and limitations of the sensing matrix are given. Implementation is based on the sparsity in the terms of voxels in a room that are occupied by a source. What is especially interesting about our solution is that we provide localization of the sound sources not only in the horizontal plane, but in the terms of the 3D coordinates inside the room.

  17. Study on a flexoelectric microphone using barium strontium titanate

    International Nuclear Information System (INIS)

    Kwon, S R; Huang, W B; Yuan, F G; Jiang, X N; Zhang, S J

    2016-01-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba 0.65 Sr 0.35 TiO 3 ) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications. (paper)

  18. Study on a flexoelectric microphone using barium strontium titanate

    Science.gov (United States)

    Kwon, S. R.; Huang, W. B.; Zhang, S. J.; Yuan, F. G.; Jiang, X. N.

    2016-04-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba0.65Sr0.35TiO3) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications.

  19. Emergency condensator

    International Nuclear Information System (INIS)

    Hamazaki, Ryoichi.

    1992-01-01

    The condensator of the present invention has a condensate return pipe for returning condensates formed by concentration of steams in a bundle of heat transfer tubes. A flow rate control valve is disposed to the return pipe, and the opening degree of the control valve is controlled by a valve opening degree control device which receives a reactor pressure signal under control. The valve opening degree control device outputs a control signal of 0% valve opening degree when reactor pressure is lower than the lowermost control value and outputs control signal of 100% value opening degree if it is greater than the uppermost control value. On the other hand, when it is between the lowermost value and the uppermost value, it outputs a control signal for demanding an opening degree in proportion to the difference between the reactor pressure and the lowermost control value. Since it is thus controlled, even if steams and condensaes are circulated as they are by natural convection, there is no worry that reactor pressure lowers excessively and no operator's manual handling is necessary. (T.M.)

  20. The practical use of electrets in a public health radon remediation campaign

    International Nuclear Information System (INIS)

    Denman, A.R.; Groves-Kirkby, C.J.; Phillips, P.S.; Crockett, R.G.M.; Woolridge, A.; Gillmore, G.K.

    2005-01-01

    As part of a long-term assessment of domestic radon in Northamptonshire, England, a batch of 50 commercially available electrets was deployed for nearly 1000 exposures, individual exposure periods ranging from one to eight weeks. Responsivity was comparable with that of recently-calibrated Durridge RAD-7 continuously-monitoring equipment. Voltage history analysis indicated mean voltage decay during manufacturers' QA assessment of 0.059 ± 0.026 V day -1 , increasing to 0.114 ± 0.073 V day -1 during storage to first use and to 0.204 ± 0.49 V day -1 during inter-deployment storage. At a representative elevated radon concentration of 500 Bq m -3 , the resulting perturbation is 3% over a 7-day deployment; at the typical mean Northamptonshire level of 80 Bq m -3 it approaches 22%. Each electret can be used for up to 25 measurements, which makes the technology attractive for organisational use. It is not suited for deployment by individual householders

  1. An effective flexible wireless energy harvester/sensor based on porous electret piezoelectric polymer

    Energy Technology Data Exchange (ETDEWEB)

    Mahanty, Biswajit [Organic Nano-Piezoelectric Device Laboratory, Department of Physics, Jadavpur University, Kolkata, 700032 (India); Department of Electronics and Communication Engineering, Saroj Mohan Institute of Technology, Hooghly, 712512 (India); Ghosh, Sujoy Kumar; Garain, Samiran [Organic Nano-Piezoelectric Device Laboratory, Department of Physics, Jadavpur University, Kolkata, 700032 (India); Mandal, Dipankar, E-mail: dipankar@phys.jdvu.ac.in [Organic Nano-Piezoelectric Device Laboratory, Department of Physics, Jadavpur University, Kolkata, 700032 (India)

    2017-01-15

    A flexible sponge-like nanogenerator (FSNG) based on ZnO nanoparticles (NPs) etched porous electret poly (vinylidene fluoride–hexafluoropropylene) (P(VDF-HFP)) film is spotlighted without any electrical poling treatment. It possesses improved dielectric and ferroelectric properties than neat P(VDF-HFP) film. The FSNG harvests an open-circuit voltage (V{sub oc}) of 9 V and short circuit current (I{sub sc}) of 1.3 μAcm{sup −2} under repeated mechanical impact of 0.36 MPa stress amplitude on the top surface. With the power density (P) of 1.21 mW/cm{sup 2} and energy conversion efficiency of 0.3% it directly operates several consumer electronics. The highly sensitive (∼1 μVPa{sup −1}) FSNG is demonstrated as a self-powered wireless sensor with 3.0% efficiency for detecting some tiny human activities including finger movements. - Highlights: • ZnO nanoparticles etched porous electret P(VDF-HFP) film is spot lighted. • Superior dielectric and ferroelectric properties without any poling are observed. • It harvests 9 V output voltage with 4.7 μA current under 0.36 MPa stress. • It shows superior power density and energy conversion efficiency of same stress. • It also acts as self-powered wireless sensor for detecting tiny human activities.

  2. Potassium ions in SiO2: electrets for silicon surface passivation

    Science.gov (United States)

    Bonilla, Ruy S.; Wilshaw, Peter R.

    2018-01-01

    This manuscript reports an experimental and theoretical study of the transport of potassium ions in thin silicon dioxide films. While alkali contamination was largely researched in the context of MOSFET instability, recent reports indicate that potassium ions can be embedded into oxide films to produce dielectric materials with permanent electric charge, also known as electrets. These electrets are integral to a number of applications, including the passivation of silicon surfaces for optoelectronic devices. In this work, electric field assisted migration of ions is used to rapidly drive K+ into SiO2 and produce effective passivation of silicon surfaces. Charge concentrations of up to ~5  ×  1012 e cm‑2 have been achieved. This charge was seen to be stable for over 1500 d, with decay time constants as high as 17 000 d, producing an effectively passivated oxide–silicon interface with SRV  <  7 cm s‑1, in 1 Ω cm n-type material. This level of charge stability and passivation effectiveness has not been previously reported. Overall, this is a new and promising methodology to enhance surface passivation for the industrial manufacture of silicon optoelectronic devices.

  3. Equivalent-circuit models for electret-based vibration energy harvesters

    Science.gov (United States)

    Phu Le, Cuong; Halvorsen, Einar

    2017-08-01

    This paper presents a complete analysis to build a tool for modelling electret-based vibration energy harvesters. The calculational approach includes all possible effects of fringing fields that may have significant impact on output power. The transducer configuration consists of two sets of metal strip electrodes on a top substrate that faces electret strips deposited on a bottom movable substrate functioning as a proof mass. Charge distribution on each metal strip is expressed by series expansion using Chebyshev polynomials multiplied by a reciprocal square-root form. The Galerkin method is then applied to extract all charge induction coefficients. The approach is validated by finite element calculations. From the analytic tool, a variety of connection schemes for power extraction in slot-effect and cross-wafer configurations can be lumped to a standard equivalent circuit with inclusion of parasitic capacitance. Fast calculation of the coefficients is also obtained by a proposed closed-form solution based on leading terms of the series expansions. The achieved analytical result is an important step for further optimisation of the transducer geometry and maximising harvester performance.

  4. Analyzing acoustic phenomena with a smartphone microphone

    Science.gov (United States)

    Kuhn, Jochen; Vogt, Patrik

    2013-02-01

    This paper describes how different sound types can be explored using the microphone of a smartphone and a suitable app. Vibrating bodies, such as strings, membranes, or bars, generate air pressure fluctuations in their immediate vicinity, which propagate through the room in the form of sound waves. Depending on the triggering mechanism, it is possible to differentiate between four types of sound waves: tone, sound, noise, and bang. In everyday language, non-experts use the terms "tone" and "sound" synonymously; however, from a physics perspective there are very clear differences between the two terms. This paper presents experiments that enable learners to explore and understand these differences. Tuning forks and musical instruments (e.g., recorders and guitars) can be used as equipment for the experiments. The data are captured using a smartphone equipped with the appropriate app (in this paper we describe the app Audio Kit for iOS systems ). The values captured by the smartphone are displayed in a screen shot and then viewed directly on the smartphone or exported to a computer graphics program for printing.

  5. Suspended polytetrafluoroethylene nanostructure electret film in dual variable cavities for self-powered micro-shock sensing

    Science.gov (United States)

    Zhu, Jianxiong; Chen, Cong; Guo, Xiaoyu

    2018-04-01

    We report a suspended polytetrafluoroethylene (PTFE) nanostructure electret film in dual variable cavities for a self-powered micro-shock sensing application. The prototype contained series variable air cavities, a suspended nanostructure PTFE electret film and independent electrode films. The charges on the suspended nanostructure PTFE electret film provided the electrostatic field around the electret film in the series variable air cavities. When the reported device was driven by a micro-shock pressure, the inducted electrostatic charges on both the top and bottom electrodes would vary as the micro-shock pressing or releasing. Experimental results showed that the maximum of a short-circuit current density (J sc ) and an open-circuit voltage (V oc ) reached 3 ± 0.1 nA cm‑2 and 3.6 ± 0.1 V, respectively. It was found that the parameter J sc was more advantageous in identifying stronger shocks (parameter acceleration a bigger than 0.1 m s‑2), whereas the parameter V oc was more sensitive for weaker shocks, such as acceleration a smaller than 0.1 m s‑2. Moreover, finger continuous micro-shock pressure taps application was used to demonstrate the mechanical energy conversion performance with 4.5 ± 0.2 V open-circuit voltages. The research on the nanostructure electret PTFE film in series dual variable air cavities not only gave us a fresh idea about the principle and design of the shocking sensor, but also provided an easy fabrication and a low cost shocking sensor for the Internet of Things (IoT) systems.

  6. Improved Open-Microphone Speech Recognition

    Science.gov (United States)

    Abrash, Victor

    2002-12-01

    Many current and future NASA missions make extreme demands on mission personnel both in terms of work load and in performing under difficult environmental conditions. In situations where hands are impeded or needed for other tasks, eyes are busy attending to the environment, or tasks are sufficiently complex that ease of use of the interface becomes critical, spoken natural language dialog systems offer unique input and output modalities that can improve efficiency and safety. They also offer new capabilities that would not otherwise be available. For example, many NASA applications require astronauts to use computers in micro-gravity or while wearing space suits. Under these circumstances, command and control systems that allow users to issue commands or enter data in hands-and eyes-busy situations become critical. Speech recognition technology designed for current commercial applications limits the performance of the open-ended state-of-the-art dialog systems being developed at NASA. For example, today's recognition systems typically listen to user input only during short segments of the dialog, and user input outside of these short time windows is lost. Mistakes detecting the start and end times of user utterances can lead to mistakes in the recognition output, and the dialog system as a whole has no way to recover from this, or any other, recognition error. Systems also often require the user to signal when that user is going to speak, which is impractical in a hands-free environment, or only allow a system-initiated dialog requiring the user to speak immediately following a system prompt. In this project, SRI has developed software to enable speech recognition in a hands-free, open-microphone environment, eliminating the need for a push-to-talk button or other signaling mechanism. The software continuously captures a user's speech and makes it available to one or more recognizers. By constantly monitoring and storing the audio stream, it provides the spoken

  7. Contact microphone using optical fibre Bragg grating technology

    International Nuclear Information System (INIS)

    Bezombes, F A; Lalor, M J; Burton, D R

    2007-01-01

    A contact microphone using optical fibre Bragg grating has been developed. It enables one to listen and record a human voice and/or breathing by monitoring the vibration generated by the outer wall of the throat during speech. This system can have many applications such as detecting defects in vocal folds, measuring and monitoring the vibration and defection generated by intubations of a patient throat and other voice related problem, low level speaking recording and transmitting is also possible, the microphone can be also used to monitor breathing and the system can be used as a microphone in very harsh environments for example it would allow one to hear the patient during a cat scan

  8. Metamorphic hemispherical microphone array for three-dimensional acoustics

    Science.gov (United States)

    Biswas, Shantonu; Reiprich, Johannes; Cohrs, Thaden; Stauden, Thomas; Pezoldt, Joerg; Jacobs, Heiko O.

    2017-07-01

    This article describes the realization of a metamorphic stretchable microphone array, which can be inflated by air to morph from a planar to a hemispherical shape. The array undergoes morphological changes to adjust their receive characteristic. To realize this device, a metamorphic printed circuit board technology (m-PCB) is described. The resulting products are millimeter-thin stretchable silicone embedded and electrically interconnected electronic structures with mechanical properties, which resemble a silicone membrane. The microphone array is used to localize a sound source in a 3D space. The results of the planar orientation (resting shape), and the 3D hemispherical orientation after air inflation are compared. The inflated hemispherical microphone array proofs to be better for 3D acoustic localization and/or beam-forming.

  9. Digital Cavity Resonance Monitor, alternative method of measuring cavity microphonics

    International Nuclear Information System (INIS)

    Tomasz Plawski; G. Davis; Hai Dong; J. Hovater; John Musson; Thomas Powers

    2005-01-01

    As is well known, mechanical vibration or microphonics in a cryomodule causes the cavity resonance frequency to change at the vibration frequency. One way to measure the cavity microphonics is to drive the cavity with a Phase Locked Loop. Measurement of the instantaneous frequency or PLL error signal provides information about the cavity microphonic frequencies. Although the PLL error signal is available directly, precision frequency measurements require additional instrumentation, a Cavity Resonance Monitor (CRM). The analog version of such a device has been successfully used for several cavity tests [1]. In this paper we present a prototype of a Digital Cavity Resonance Monitor designed and built in the last year. The hardware of this instrument consists of an RF downconverter, digital quadrature demodulator and digital processor motherboard (Altera FPGA). The motherboard processes received data and computes frequency changes with a resolution of 0.2 Hz, with a 3 kHz output bandwidth

  10. Design of robust differential microphone arrays with orthogonal polynomials.

    Science.gov (United States)

    Pan, Chao; Benesty, Jacob; Chen, Jingdong

    2015-08-01

    Differential microphone arrays have the potential to be widely deployed in hands-free communication systems thanks to their frequency-invariant beampatterns, high directivity factors, and small apertures. Traditionally, they are designed and implemented in a multistage way with uniform linear geometries. This paper presents an approach to the design of differential microphone arrays with orthogonal polynomials, more specifically with Jacobi polynomials. It first shows how to express the beampatterns as a function of orthogonal polynomials. Then several differential beamformers are derived and their performance depends on the parameters of the Jacobi polynomials. Simulations show the great flexibility of the proposed method in terms of designing any order differential microphone arrays with different beampatterns and controlling white noise gain.

  11. Acoustic Source Localization in Aircraft Interiors Using Microphone Array Technologies

    Science.gov (United States)

    Sklanka, Bernard J.; Tuss, Joel R.; Buehrle, Ralph D.; Klos, Jacob; Williams, Earl G.; Valdivia, Nicolas

    2006-01-01

    Using three microphone array configurations at two aircraft body stations on a Boeing 777-300ER flight test, the acoustic radiation characteristics of the sidewall and outboard floor system are investigated by experimental measurement. Analysis of the experimental data is performed using sound intensity calculations for closely spaced microphones, PATCH Inverse Boundary Element Nearfield Acoustic Holography, and Spherical Nearfield Acoustic Holography. Each method is compared assessing strengths and weaknesses, evaluating source identification capability for both broadband and narrowband sources, evaluating sources during transient and steady-state conditions, and quantifying field reconstruction continuity using multiple array positions.

  12. Chip-size-packaged silicon microphones [for hearing instruments

    DEFF Research Database (Denmark)

    Müllenborn, Matthias; Rombach, Pirmin; Klein, Udo

    2001-01-01

    The first results of silicon microphones that are completely batch-packaged and integrated with signal conditioning circuitry in a chip stack are discussed. The chip stack is designed to be directly mounted into a system, such as a hearing instrument, without further single-chip handling or wire...... consumption of about 50 μW in the near future, thereby living up to the tight specifications of microphones for hearing instruments. Other potential applications include mobile phones, headsets, and wearable computers, in which space is constrained....

  13. Influence of a remote microphone on localization with hearing aids

    DEFF Research Database (Denmark)

    Selby, Johan G.; Weisser, Adam; MacDonald, Ewen

    2017-01-01

    When used with hearing aids (HA), the addition of a remote microphone (RM) may alter the spatial perception of the listener. First, the RM signal is presented diotically from the HAs. Second, the processing in the HA often delays the RM signal relative to the HA microphone signals. Finally......, the level of the RM signal is independent of the distance from the RM to HA. The present study investigated localization performance of 15 normal-hearing and 9 hearing-impaired listeners under conditions simulating the use of an RM with a behind the ear (BTE) HA. Minimum audible angle discrimination around...

  14. Outlier Detection for Sensor Systems (ODSS): A MATLAB Macro for Evaluating Microphone Sensor Data Quality

    OpenAIRE

    Vasta, Robert; Crandell, Ian; Millican, Anthony; House, Leanna; Smith, Eric

    2017-01-01

    Microphone sensor systems provide information that may be used for a variety of applications. Such systems generate large amounts of data. One concern is with microphone failure and unusual values that may be generated as part of the information collection process. This paper describes methods and a MATLAB graphical interface that provides rapid evaluation of microphone performance and identifies irregularities. The approach and interface are described. An application to a microphone array us...

  15. Outlier Detection for Sensor Systems (ODSS): A MATLAB Macro for Evaluating Microphone Sensor Data Quality.

    Science.gov (United States)

    Vasta, Robert; Crandell, Ian; Millican, Anthony; House, Leanna; Smith, Eric

    2017-10-13

    Microphone sensor systems provide information that may be used for a variety of applications. Such systems generate large amounts of data. One concern is with microphone failure and unusual values that may be generated as part of the information collection process. This paper describes methods and a MATLAB graphical interface that provides rapid evaluation of microphone performance and identifies irregularities. The approach and interface are described. An application to a microphone array used in a wind tunnel is used to illustrate the methodology.

  16. On experimental determination of the random-incidence response of microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2007-01-01

    The random-incidence sensitivity of a microphone is defined as the ratio of the output voltage to the sound pressure that would exist at the position of the acoustic center of the microphone in the absence of the microphone in a sound field with incident plane waves coming from all directions. Th...

  17. 78 FR 45272 - Certain Silicon Microphone Packages and Products Containing Same Institution of Investigation...

    Science.gov (United States)

    2013-07-26

    ... COMMISSION Certain Silicon Microphone Packages and Products Containing Same Institution of Investigation... importation, and the sale within the United States after importation of certain silicon microphone packages... importation, or the sale within the United States after importation of certain silicon microphone packages and...

  18. 76 FR 78042 - Certain Silicon Microphone Packages and Products Containing Same Receipt of Complaint...

    Science.gov (United States)

    2011-12-15

    ... COMMISSION Certain Silicon Microphone Packages and Products Containing Same Receipt of Complaint... complaint entitled In Re Certain Silicon Microphone Packages and Products Containing Same, DN 2864; the... importation of certain silicon microphone packages and products containing same. The complaint names Analog...

  19. 77 FR 2087 - Certain Silicon Microphone Packages and Products Containing Same; Institution of Investigation

    Science.gov (United States)

    2012-01-13

    ... COMMISSION Certain Silicon Microphone Packages and Products Containing Same; Institution of Investigation... importation, and the sale within the United States after importation of certain silicon microphone packages... after importation of certain silicon microphone packages and products containing same that infringe one...

  20. Measurement of Gravitational Acceleration Using a Computer Microphone Port

    Science.gov (United States)

    Khairurrijal; Eko Widiatmoko; Srigutomo, Wahyu; Kurniasih, Neny

    2012-01-01

    A method has been developed to measure the swing period of a simple pendulum automatically. The pendulum position is converted into a signal frequency by employing a simple electronic circuit that detects the intensity of infrared light reflected by the pendulum. The signal produced by the electronic circuit is sent to the microphone port and…

  1. Free-field calibration of measurement microphones at high frequencies

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Torras Rosell, Antoni

    2011-01-01

    Measurement microphones are typically calibrated in a free field at frequencies up to 50 kHz. This is a sufficiently high frequency for the most of sound measurement applications related with noise assessment. However, other applications such as assessment of the noise emitted by ultrasound clean...

  2. Reproducibility of Dual-Microphone Voice Range Profile Equipment

    Science.gov (United States)

    Printz, Trine; Pedersen, Ellen Raben; Juhl, Peter; Nielsen, Troels; Grøntved, Ågot Møller; Godballe, Christian

    2017-01-01

    Purpose: The aim of this study was to add further knowledge about the usefulness of the Voice Range Profile (VRP) assessment in clinical settings and research by analyzing VRP dual-microphone equipment precision, reliability, and room effect. Method: Test-retest studies were conducted in an anechoic chamber and an office: (a) comparing sound…

  3. Design and analysis of diaphragms in dynamic microphones

    Directory of Open Access Journals (Sweden)

    Zi-Gui Huang

    2015-07-01

    Full Text Available Most contemporary high-end microphones are dynamic microphones, adopting the most basic electromagnetic transduction principles. This study investigated the diaphragm structures of dynamic microphones. The diaphragms were composed of polyimide material, and the boundary settings required for actual operation were provided using finite element model analysis software. The characteristic frequencies caused by grooving variations on the three-dimensional diaphragm were analyzed for the various groove shapes and number. The groove angles and width variations were examined based on the optimal groove shape selected in the aforementioned analysis, and the effects of these shapes were determined based on the analytical results. Acoustic waves cause thin films to vibrate, forming the working principle behind dynamic microphones. The thin film drives a coil to vibrate in a magnetic field and cuts the line of magnetic force, subsequently producing a voltage on both ends of the coil. This audio-frequency-inducted voltage represents an acoustic wave message. The finite element model analysis software was used to conduct electromagnetic induction simulations; the sound source was fed to the diaphragm to drive the coil. The coil vibrations caused the line of magnetic force to be cut, and the final voltages produced were examined and compared.

  4. Remote Microphone System Use at Home: Impact on Caregiver Talk

    Science.gov (United States)

    Benítez-Barrera, Carlos R.; Angley, Gina P.; Tharpe, Anne Marie

    2018-01-01

    Purpose: The purpose of this study was to investigate the effects of home use of a remote microphone system (RMS) on the spoken language production of caregivers with young children who have hearing loss. Method: Language Environment Analysis recorders were used with 10 families during 2 consecutive weekends (RMS weekend and No-RMS weekend). The…

  5. Development of PVF2 Noise-Cancelling Microphone

    Science.gov (United States)

    1979-03-01

    the United States it Is produced under the trade name KYNAR by Pennwalt Corporation, Philadelphia, PA. An important producer in Japan is Kureha ...subsidiary of Kureha Chemical Industry Co., Ltd. )I **Data from Gulton Industries, Irp. 4 2.0 PERFORMANCE OF THE PVF 2 MICROPHONE 2.1 POWER SUPPLY

  6. MP.EXE Microphone pressure sensitivity calibration calculation program

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1999-01-01

    MP.EXE is a program which calculates the pressure sensitivity of LS1 microphones as defined in IEC 61094-1, based on measurement results performed as laid down in IEC 61094-2.A very early program was developed and written by K. Rasmussen. The code of the present heavily extended version is written...

  7. Chip-size-packaged silicon microphones [for hearing instruments

    DEFF Research Database (Denmark)

    Müllenborn, Matthias; Rombach, Pirmin; Klein, Udo

    2001-01-01

    bonding. The devices are fully encapsulated and provided with a well-determined interface to the environment. The integrated microphones operate at a bias of 1.5 V and are expected to reach a sensitivity of 5 mV/Pa, an A-weighted equivalent input noise of 24 dB sound pressure level, and a power...

  8. Near field acoustic holography with microphones on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Moreno-Pescador, Guillermo; Fernandez Grande, Efren

    2011-01-01

    Spherical near field acoustic holography (spherical NAH) is a technique that makes it possible to reconstruct the sound field inside and just outside a spherical surface on which the sound pressure is measured with an array of microphones. This is potentially very useful for source identification...

  9. Wake Vortex Detection: Phased Microphone vs. Linear Infrasonic Array

    Science.gov (United States)

    Shams, Qamar A.; Zuckerwar, Allan J.; Sullivan, Nicholas T.; Knight, Howard K.

    2014-01-01

    Sensor technologies can make a significant impact on the detection of aircraft-generated vortices in an air space of interest, typically in the approach or departure corridor. Current state-of-the art sensor technologies do not provide three-dimensional measurements needed for an operational system or even for wake vortex modeling to advance the understanding of vortex behavior. Most wake vortex sensor systems used today have been developed only for research applications and lack the reliability needed for continuous operation. The main challenges for the development of an operational sensor system are reliability, all-weather operation, and spatial coverage. Such a sensor has been sought for a period of last forty years. Acoustic sensors were first proposed and tested by National Oceanic and Atmospheric Administration (NOAA) early in 1970s for tracking wake vortices but these acoustic sensors suffered from high levels of ambient noise. Over a period of the last fifteen years, there has been renewed interest in studying noise generated by aircraft wake vortices, both numerically and experimentally. The German Aerospace Center (DLR) was the first to propose the application of a phased microphone array for the investigation of the noise sources of wake vortices. The concept was first demonstrated at Berlins Airport Schoenefeld in 2000. A second test was conducted in Tarbes, France, in 2002, where phased microphone arrays were applied to study the wake vortex noise of an Airbus 340. Similarly, microphone phased arrays and other opto-acoustic microphones were evaluated in a field test at the Denver International Airport in 2003. For the Tarbes and Denver tests, the wake trajectories of phased microphone arrays and lidar were compared as these were installed side by side. Due to a built-in pressure equalization vent these microphones were not suitable for capturing acoustic noise below 20 Hz. Our group at NASA Langley Research Center developed and installed an

  10. Feasible pickup from intact ossicular chain with floating piezoelectric microphone

    Directory of Open Access Journals (Sweden)

    Kang Hou-Yong

    2012-02-01

    Full Text Available Abstract Objectives Many microphones have been developed to meet with the implantable requirement of totally implantable cochlear implant (TICI. However, a biocompatible one without destroying the intactness of the ossicular chain still remains under investigation. Such an implantable floating piezoelectric microphone (FPM has been manufactured and shows an efficient electroacoustic performance in vitro test at our lab. We examined whether it pick up sensitively from the intact ossicular chain and postulated whether it be an optimal implantable one. Methods Animal controlled experiment: five adult cats (eight ears were sacrificed as the model to test the electroacoustic performance of the FPM. Three groups were studied: (1 the experiment group (on malleus: the FPM glued onto the handle of the malleus of the intact ossicular chains; (2 negative control group (in vivo: the FPM only hung into the tympanic cavity; (3 positive control group (Hy-M30: a HiFi commercial microphone placed close to the site of the experiment ear. The testing speaker played pure tones orderly ranged from 0.25 to 8.0 kHz. The FPM inside the ear and the HiFi microphone simultaneously picked up acoustic vibration which recorded as .wav files to analyze. Results The FPM transformed acoustic vibration sensitively and flatly as did the in vitro test across the frequencies above 2.0 kHz, whereas inefficiently below 1.0 kHz for its overloading mass. Although the HiFi microphone presented more efficiently than the FPM did, there was no significant difference at 3.0 kHz and 8.0 kHz. Conclusions It is feasible to develop such an implantable FPM for future TICIs and TIHAs system on condition that the improvement of Micro Electromechanical System and piezoelectric ceramic material technology would be applied to reduce its weight and minimize its size.

  11. Dropwise condensation originating

    International Nuclear Information System (INIS)

    Croix, J.-M.

    1975-01-01

    Both principal modes of steam condensation (film or dropwise condensation) are surveyed. Available results are exposed as for contact angle measurements, and the heat transfer mechanisms proposed. The efficiency of the dropwise condensation mode is illustrated from the excellent results obtained in the laboratory by J.M. NIEZBORALA, using an organic compound (fluorinated disulfide) for originating the condensation [fr

  12. Fabrication, Polarization of Electrospun Polyvinylidene Fluoride Electret Fibers and Effect on Capturing Nanoscale Solid Aerosols

    Directory of Open Access Journals (Sweden)

    Dinesh Lolla

    2016-08-01

    Full Text Available Electrospun polyvinylidene fluoride (PVDF fiber mats with average fiber diameters (≈200 nm, ≈2000 nm were fabricated by controlled electrospinning conditions. These fiber mats were polarized using a custom-made device to enhance the formation of the electret β-phase ferroelectric property of the fibers by simultaneous uniaxial stretching of the fiber mat and heating the mat to the Curie temperature of the PVDF polymer in a strong electric field of 2.5 kV/cm. Scanning electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry and Brunauer-Emmett-Teller (BET surface area analyses were performed to characterize both the internal and external morphologies of the fiber mat samples to study polarization-associated changes. MATLAB simulations revealed the changes in the paths of the electric fields and the magnetic flux inside the polarization field with inclusion of the ferroelectric fiber mats. Both polarized and unpolarized fiber mats were challenged as filters against NaCl particles with average particle diameters of about 150 nm using a TSI 8130 to study capture efficiencies and relative pressure drops. Twelve filter experiments were conducted on each sample at one month time intervals between experiments to evaluate the reduction of the polarization enhancement over time. The results showed negligible polarization loss for the 200-nm fiber sample. The polarized mats had the highest filter efficiencies and lowest pressure drops.

  13. Shock reliability analysis and improvement of MEMS electret-based vibration energy harvesters

    International Nuclear Information System (INIS)

    Renaud, M; Goedbloed, M; De Nooijer, C; Van Schaijk, R; Fujita, T

    2015-01-01

    Vibration energy harvesters can serve as a replacement solution to batteries for powering tire pressure monitoring systems (TPMS). Autonomous wireless TPMS powered by microelectromechanical system (MEMS) electret-based vibration energy harvester have been demonstrated. The mechanical reliability of the MEMS harvester still has to be assessed in order to bring the harvester to the requirements of the consumer market. It should survive the mechanical shocks occurring in the tire environment. A testing procedure to quantify the shock resilience of harvesters is described in this article. Our first generation of harvesters has a shock resilience of 400 g, which is far from being sufficient for the targeted application. In order to improve this aspect, the first important aspect is to understand the failure mechanism. Failure is found to occur in the form of fracture of the device’s springs. It results from impacts between the anchors of the springs when the harvester undergoes a shock. The shock resilience of the harvesters can be improved by redirecting these impacts to nonvital parts of the device. With this philosophy in mind, we design three types of shock absorbing structures and test their effect on the shock resilience of our MEMS harvesters. The solution leading to the best results consists of rigid silicon stoppers covered by a layer of Parylene. The shock resilience of the harvesters is brought above 2500 g. Results in the same range are also obtained with flexible silicon bumpers, which are simpler to manufacture. (paper)

  14. Shock reliability analysis and improvement of MEMS electret-based vibration energy harvesters

    Science.gov (United States)

    Renaud, M.; Fujita, T.; Goedbloed, M.; de Nooijer, C.; van Schaijk, R.

    2015-10-01

    Vibration energy harvesters can serve as a replacement solution to batteries for powering tire pressure monitoring systems (TPMS). Autonomous wireless TPMS powered by microelectromechanical system (MEMS) electret-based vibration energy harvester have been demonstrated. The mechanical reliability of the MEMS harvester still has to be assessed in order to bring the harvester to the requirements of the consumer market. It should survive the mechanical shocks occurring in the tire environment. A testing procedure to quantify the shock resilience of harvesters is described in this article. Our first generation of harvesters has a shock resilience of 400 g, which is far from being sufficient for the targeted application. In order to improve this aspect, the first important aspect is to understand the failure mechanism. Failure is found to occur in the form of fracture of the device’s springs. It results from impacts between the anchors of the springs when the harvester undergoes a shock. The shock resilience of the harvesters can be improved by redirecting these impacts to nonvital parts of the device. With this philosophy in mind, we design three types of shock absorbing structures and test their effect on the shock resilience of our MEMS harvesters. The solution leading to the best results consists of rigid silicon stoppers covered by a layer of Parylene. The shock resilience of the harvesters is brought above 2500 g. Results in the same range are also obtained with flexible silicon bumpers, which are simpler to manufacture.

  15. Theory and applications of spherical microphone array processing

    CERN Document Server

    Jarrett, Daniel P; Naylor, Patrick A

    2017-01-01

    This book presents the signal processing algorithms that have been developed to process the signals acquired by a spherical microphone array. Spherical microphone arrays can be used to capture the sound field in three dimensions and have received significant interest from researchers and audio engineers. Algorithms for spherical array processing are different to corresponding algorithms already known in the literature of linear and planar arrays because the spherical geometry can be exploited to great beneficial effect. The authors aim to advance the field of spherical array processing by helping those new to the field to study it efficiently and from a single source, as well as by offering a way for more experienced researchers and engineers to consolidate their understanding, adding either or both of breadth and depth. The level of the presentation corresponds to graduate studies at MSc and PhD level. This book begins with a presentation of some of the essential mathematical and physical theory relevant to ...

  16. Reconstruction of sound fields with a spherical microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Walton, Tim

    2014-01-01

    Spherical microphone arrays are very well suited for sound field measurements in enclosures or interior spaces, and generally in acoustic environments where sound waves impinge on the array from multiple directions. Because of their directional properties, they make it possible to resolve sound...... waves traveling in any direction. In particular, rigid sphere microphone arrays are robust, and have the favorable property that the scattering introduced by the array can be compensated for - making the array virtually transparent. This study examines a recently proposed sound field reconstruction...... method based on a point source expansion, i.e. equivalent source method, using a rigid spherical array. The study examines the capability of the method to distinguish between sound waves arriving from different directions (i.e., as a sound field separation method). This is representative of the potential...

  17. Condensate treatment system

    International Nuclear Information System (INIS)

    Masumitsu, Isao; Ito, Tomoaki; Kajio, Shozo; Takayama, Toshio; Ishikawa, Yasuyuki

    1992-01-01

    Condensate treatment system is installed for purifying condensate in thermal and nuclear power stations. Once-through boilers appeared, and in order to maintain the high purity water quality of condensate, condensate desalting facilities were installed in 1962 in Japan. There are the single type using condensate desalting facility only and the combined type of condensate prefilter and condensate desalting facility. The purpose of installing condensate treatment system is to remove corrosion products and ion components generated from the structural materials of plants and to remove sea water composition if it leaks. The general steam-condensate system in thermal power plants is explained. A standard JIS B 8223 'Quality of feedwater and boiler water for boilers' is instituted. The water treatment for boilers is carried out by the treatment of makeup feed, chemical treatment in boilers and blow. In the case of once-through boilers, blow cannot be done, accordingly, very high purity water is required. Condensate prefilter, condensate desalting facility, the watching of condensate treatment system and the operation in combined water treatment are reported. Also the condensate prefilters and the condensate desalting facilities for BWR and PWR plants are described. (K.I.)

  18. Microphones and Knock Sensors for Feedback Control of HCCI Engines

    OpenAIRE

    Souder, Jason S; Mack, John Hunter; Hedrick, J. Karl; Dibble, Robert W

    2004-01-01

    Homogeneous charge compression ignition (HCCI) engines lack direct in-cylinder mechanisms, such as spark plugs or direct fuel injection, for controlling the combustion timing. Many indirect methods have been used to control the combustion timing in an HCCI engine. With any indirect method, it is important to have a measure of the combustion timing so the control inputs can be adjusted for the next cycle. In this paper, it is shown that microphones and knock sensors can be used to detect combu...

  19. Micromechanical microphone using sideband modulation of nonlinear resonators

    Science.gov (United States)

    Boales, Joseph A.; Mateen, Farrukh; Mohanty, Pritiraj

    2017-08-01

    We report successful detection of an audio signal via sideband modulation of a nonlinear piezoelectric micromechanical resonator. The 270 × 96-μm resonator was shown to be reliable in audio detection for sound intensity levels as low as ambient room noise and to have an unamplified sensitivity of 23.9 μV/Pa. Such an approach may be adapted in acoustic sensors and microphones for consumer electronics or medical equipment such as hearing aids.

  20. Factors affecting the performance of large-aperture microphone arrays

    Science.gov (United States)

    Silverman, Harvey F.; Patterson, William R.; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m×8 m×3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  1. Noise Reduction with Microphone Arrays for Speaker Identification

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Z

    2011-12-22

    Reducing acoustic noise in audio recordings is an ongoing problem that plagues many applications. This noise is hard to reduce because of interfering sources and non-stationary behavior of the overall background noise. Many single channel noise reduction algorithms exist but are limited in that the more the noise is reduced; the more the signal of interest is distorted due to the fact that the signal and noise overlap in frequency. Specifically acoustic background noise causes problems in the area of speaker identification. Recording a speaker in the presence of acoustic noise ultimately limits the performance and confidence of speaker identification algorithms. In situations where it is impossible to control the environment where the speech sample is taken, noise reduction filtering algorithms need to be developed to clean the recorded speech of background noise. Because single channel noise reduction algorithms would distort the speech signal, the overall challenge of this project was to see if spatial information provided by microphone arrays could be exploited to aid in speaker identification. The goals are: (1) Test the feasibility of using microphone arrays to reduce background noise in speech recordings; (2) Characterize and compare different multichannel noise reduction algorithms; (3) Provide recommendations for using these multichannel algorithms; and (4) Ultimately answer the question - Can the use of microphone arrays aid in speaker identification?

  2. A low-noise/low-power preamplifier for capacitive microphones

    DEFF Research Database (Denmark)

    Fürst, Claus Erdmann

    1996-01-01

    A design for a microphone preamplifier for application in hearing aids is presented. The amplifier operates at a supply of 1-1.5 V, the current drain is 40 μA. The maximum sound level allowed is more than 120 dB SPL (Sound Pressure Level), with a typical noise level of 25 dB(A) SPL (A-weighted). ......A design for a microphone preamplifier for application in hearing aids is presented. The amplifier operates at a supply of 1-1.5 V, the current drain is 40 μA. The maximum sound level allowed is more than 120 dB SPL (Sound Pressure Level), with a typical noise level of 25 dB(A) SPL (A......-weighted). The amplifier is optimized for a capacitive microphone with a capacitance of 1.2 pF. The amplifier is fully integrated in a 0.7 μm n-well CMOS technology. Design details concerning noise performance are analytically described...

  3. Microphone variability and degradation: implications for monitoring programs employing autonomous recording units

    Directory of Open Access Journals (Sweden)

    Patrick J. Turgeon

    2017-06-01

    Full Text Available Autonomous recording units (ARUs are emerging as an effective tool for avian population monitoring and research. Although ARU technology is being rapidly adopted, there is a need to establish whether variation in ARU components and their degradation with use might introduce detection biases that would affect long-term monitoring and research projects. We assessed whether microphone sensitivity impacted the probability of detecting bird vocalizations by broadcasting a sequence of 12 calls toward an array of commercially available ARUs equipped with microphones of varying sensitivities under three levels (32 dBA, 42 dBA, and 50 dBA of experimentally induced noise conditions selected to reflect the range of noise levels commonly encountered during avian surveys. We used binomial regression to examine factors influencing probability of detection for each species and used these to examine the impact of microphone sensitivity on the effective detection area (ha for each species. Microphone sensitivity loss reduced detection probability for all species examined, but the magnitude of the effect varied between species and often interacted with distance. Microphone sensitivity loss reduced the effective detection area by an average of 25% for microphones just beyond manufacturer specifications (-5 dBV and by an average of 66% for severely compromised microphones (-20 dBV. Microphone sensitivity loss appeared to be more problematic for low frequency calls where reduction in the effective detection area occurred most rapidly. Microphone degradation poses a source of variation in avian surveys made with ARUs that will require regular measurement of microphone sensitivity and criteria for microphone replacement to ensure scientifically reproducible results. We recommend that research and monitoring projects employing ARUs test their microphones regularly, replace microphones with declining sensitivity, and record sensitivity as a potential covariate in

  4. Robust Speaker Recognition with Combined Use of Acoustic and Throat Microphone Speech

    DEFF Research Database (Denmark)

    Sahidullah, Md; Gonzalez Hautamäki, Rosa; Thomsen, Dennis Alexander Lehmann

    2016-01-01

    Accuracy of automatic speaker recognition (ASV) systems degrades severely in the presence of background noise. In this paper, we study the use of additional side information provided by a body-conducted sensor, throat microphone. Throat microphone signal is much less affected by background noise...... in comparison to acoustic microphone signal. This makes throat microphones potentially useful for feature extraction or speech activity detection. This paper, firstly, proposes a new prototype system for simultaneous data-acquisition of acoustic and throat microphone signals. Secondly, we study the use...... of this additional information for both speech activity detection, feature extraction and fusion of the acoustic and throat microphone signals. We collect a pilot database consisting of 38 subjects including both clean and noisy sessions. We carry out speaker verification experiments using Gaussian mixture model...

  5. An underestimated issue: unsuspected decrease of sound processor microphone sensitivity, technical, and clinical evaluation.

    Science.gov (United States)

    Razza, Sergio; Burdo, Sandro

    2011-05-01

    To describe the rate of occurrence of unsuspected decrease in sensitivity of the sound processor microphone and to evaluate its effect on the patient's audiological performance in terms of reduction in speech recognition scores. Speech processor microphones were tested by connecting the speech processor acoustic monitor circuit to a hearing aid analyzer. The response curves were compared with those obtained from fully working microphones. During a 6-month investigation period, microphone response curves were measured from a group of cochlear implant recipients who had not reported any problems. Despite the absence of any subjective problem, some microphones were found to show a loss of sensitivity. Their users, aged between 4 and 67 years, were tested both with the defective and a working microphone in order to calculate the correlation between the degree of microphone failure and the decline in audiological performance. To quantify the effect of microphone failure, patients' speech recognition skills were measured by live voice connected discourse tracking series administered in different conditions and by recorded sentences lists. A total of 120 apparently fully functioning sound processors were tested in the investigation: 33 (27.5%) were affected by a subjectively unreported sensitivity decrease. Speech-tracking scores correlated significantly with the loss of microphone sensitivity in all test conditions (r = 0.69-0.77, P processor microphone sensitivity causes a degree of hearing decline that negatively affects the cochlear recipient's clinical performance. Microphone faults are often unreported events, and their occurrence rate is underestimated. To establish that the microphone is providing correct input to the speech processor a standard control procedure, including technical and clinical checks, is needed in clinical practice.

  6. High Channel Count, High Density Microphone Arrays for Wind Tunnel Environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Interdisciplinary Consulting Corporation (IC2) proposes the development of high channel count, high density, reduced cost per channel, directional microphone...

  7. Outlier Detection for Sensor Systems (ODSS: A MATLAB Macro for Evaluating Microphone Sensor Data Quality

    Directory of Open Access Journals (Sweden)

    Robert Vasta

    2017-10-01

    Full Text Available Microphone sensor systems provide information that may be used for a variety of applications. Such systems generate large amounts of data. One concern is with microphone failure and unusual values that may be generated as part of the information collection process. This paper describes methods and a MATLAB graphical interface that provides rapid evaluation of microphone performance and identifies irregularities. The approach and interface are described. An application to a microphone array used in a wind tunnel is used to illustrate the methodology.

  8. Condensation in insulated homes

    Energy Technology Data Exchange (ETDEWEB)

    Wiley, R A

    1978-05-28

    A research proposal on condensation in insulated homes is presented. Information is provided on: justification for condensation control; previous work and present outlook (good vapor barrier, condensation and retrofit insulation, vapor barrier decreases condensation, brick-veneer walls, condensation in stress-skin panels, air-conditioned buildings, retrofitting for conservation, study on mobile homes, high indoor relative humidity, report on various homes); and procedure (after funding has been secured). Measures are briefly described on opening walls, testing measures, and retrofitting procedures. An extensive bibliography and additional informative citations are included. (MCW)

  9. Modelling of condensation phenomena

    International Nuclear Information System (INIS)

    Jeong, Jae Jun; Chang, Won Pyo

    1996-07-01

    Condensation occurs when vapor is cooled sufficiently below the saturation temperature to induce the nucleation of droplets. Such nucleation may occur homogeneously within the vapor or heterogeneously on entrained particular matter. Heterogeneous nucleation may occur on the walls of the system, where the temperature is below the saturation temperature. There are two forms of heterogeneous condensation, drop-wise and film-wise. Another form of condensation occurs when vapor directly contacts to subcooled liquid. In nuclear power plant systems, all forms of condensation may occur during normal operation or accident conditions. In this work the modelling of condensation is surveyed, including the Nusselts' laminar film condensation theory in 1916, Rohsenow's turbulent film condensation model in 1950s, and Chen's models in 1987. Major attention is paid on the film condensation models among various research results because of its importance in engineering applications. It is found that theory, experiment, and empirical correlations for film condensation are well established, but research for drop-wise and direct-contact condensation are not sufficient yet. Condensation models in the best-estimate system codes such as RELAP5/MOD3 and CATHARE2 are also investigated. 3 tabs., 11 figs., 36 refs. (Author)

  10. Llamas: Large-area microphone arrays and sensing systems

    Science.gov (United States)

    Sanz-Robinson, Josue

    Large-area electronics (LAE) provides a platform to build sensing systems, based on distributing large numbers of densely spaced sensors over a physically-expansive space. Due to their flexible, "wallpaper-like" form factor, these systems can be seamlessly deployed in everyday spaces. They go beyond just supplying sensor readings, but rather they aim to transform the wealth of data from these sensors into actionable inferences about our physical environment. This requires vertically integrated systems that span the entirety of the signal processing chain, including transducers and devices, circuits, and signal processing algorithms. To this end we develop hybrid LAE / CMOS systems, which exploit the complementary strengths of LAE, enabling spatially distributed sensors, and CMOS ICs, providing computational capacity for signal processing. To explore the development of hybrid sensing systems, based on vertical integration across the signal processing chain, we focus on two main drivers: (1) thin-film diodes, and (2) microphone arrays for blind source separation: 1) Thin-film diodes are a key building block for many applications, such as RFID tags or power transfer over non-contact inductive links, which require rectifiers for AC-to-DC conversion. We developed hybrid amorphous / nanocrystalline silicon diodes, which are fabricated at low temperatures (<200 °C) to be compatible with processing on plastic, and have high current densities (5 A/cm2 at 1 V) and high frequency operation (cutoff frequency of 110 MHz). 2) We designed a system for separating the voices of multiple simultaneous speakers, which can ultimately be fed to a voice-command recognition engine for controlling electronic systems. On a device level, we developed flexible PVDF microphones, which were used to create a large-area microphone array. On a circuit level we developed localized a-Si TFT amplifiers, and a custom CMOS IC, for system control, sensor readout and digitization. On a signal processing

  11. Patch holography using a double layer microphone array

    DEFF Research Database (Denmark)

    Gomes, Jesper Skovhus

    a closed local element mesh that surrounds the microphone array, and with a part of the mesh coinciding with a patch, the entire source is not needed in the model. Since the array has two layers, sources/reflections behind the array are also allowed. The Equivalent Source Method (ESM) is another technique...... in which the sound field is represented by a set of monopoles placed inside the source. In this paper these monopoles are distributed so that they surround the array, and the reconstruction is compared with the IBEM-based approach. The comparisons are based on computer simulations with a planar double...... layer array and sources with different shapes....

  12. Proceedings: Condenser technology conference

    International Nuclear Information System (INIS)

    Tsou, J.L.; Mussalli, Y.G.

    1991-08-01

    Seam surface condenser and associated systems performance strongly affects availability and heat rate in nuclear and fossil power plants. Thirty-six papers presented at a 1990 conference discuss research results, industry experience, and case histories of condenser problems and solutions. This report contains papers on life extension, performance improvement, corrosion and failure analysis, fouling prevention, and recommendation for future R ampersand D. The information represents recent work on condenser problems and solutions to improve the procurement, operation, and maintenance functions of power plant personnel. Several key points follow: A nuclear and a fossil power plant report show that replacing titanium tube bundles improves condenser availability and performance. One paper reports 10 years of experience with enhanced heat transfer tubes in utility condensers. The newly developed enhanced condenser tubes could further improve condensing heat transfer. A new resistance summation method improves the accuracy of condenser performance prediction, especially for stainless steel and titanium tubed condensers. Several papers describe improved condenser fouling monitoring techniques, including a review of zebra mussel issues

  13. Implementation issues of the nearfield equivalent source imaging microphone array

    Science.gov (United States)

    Bai, Mingsian R.; Lin, Jia-Hong; Tseng, Chih-Wen

    2011-01-01

    This paper revisits a nearfield microphone array technique termed nearfield equivalent source imaging (NESI) proposed previously. In particular, various issues concerning the implementation of the NESI algorithm are examined. The NESI can be implemented in both the time domain and the frequency domain. Acoustical variables including sound pressure, particle velocity, active intensity and sound power are calculated by using multichannel inverse filters. Issues concerning sensor deployment are also investigated for the nearfield array. The uniform array outperformed a random array previously optimized for far-field imaging, which contradicts the conventional wisdom in far-field arrays. For applications in which only a patch array with scarce sensors is available, a virtual microphone approach is employed to ameliorate edge effects using extrapolation and to improve imaging resolution using interpolation. To enhance the processing efficiency of the time-domain NESI, an eigensystem realization algorithm (ERA) is developed. Several filtering methods are compared in terms of computational complexity. Significant saving on computations can be achieved using ERA and the frequency-domain NESI, as compared to the traditional method. The NESI technique was also experimentally validated using practical sources including a 125 cc scooter and a wooden box model with a loudspeaker fitted inside. The NESI technique proved effective in identifying broadband and non-stationary sources produced by the sources.

  14. Condensate cleaning systems

    International Nuclear Information System (INIS)

    Yamamoto, Michiyoshi; Oosumi, Katsumi; Takashima, Yoshie; Mitani, Shinji.

    1982-01-01

    Purpose: To decrease the frequency for the backwash and regeneration operations due to the increase in the differential pressure resulted from claddings captured in a mixed floor type desalter, and decrease the amount of radioactive liquid wastes of claddings from the condensate systems by removing claddings with electromagnetic filters. Constitution: In an existent plant, a valves is disposed between a condensate pump and a mixed floor type desalter. A pipeway is branched from a condensate pipe between the condensate pipe and the valve, through which condensates are transferred by a pump to an electromagnetic filter such as of a high gradient type electromagntic filter to remove claddings, then returned to a condensate pipe between the valve and the mixed floor type desalter and, thereafter, are removed with ionic components in the mixed floor type desalter and fed to the reactor. (Yoshino, Y.)

  15. On the interference between the two microphones in free-field reciprocity calibration

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2004-01-01

    is not strictly valid. The interference has been thought to be caused by specular reflection between the parallel diaphragms of the microphones, and a solution based on tilting the axis of one of the microphones a few degrees has been proposed, but never examined in practice. In this paper a time...

  16. A note on determination of the diffuse-field sensitivity of microphones using the reciprocity technique

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Jacobsen, Finn

    2008-01-01

    The diffuse-field response of a microphone is usually obtained by adding a random-incidence correction to the pressure response of the microphone. However, the random-incidence correction is determined from a relative measurement, and its accuracy depends not only on the relative response at all ...

  17. Robustness of a Mixed-Order Ambisonics Microphone Array for Sound Field Reproduction

    DEFF Research Database (Denmark)

    Marschall, Marton; Favrot, Sylvain Emmanuel; Buchholz, Jörg

    2012-01-01

    Spherical microphone arrays can be used to capture and reproduce the spatial characteristics of acoustic scenes. A mixed-order Ambisonics (MOA) approach was recently proposed to improve the horizontal spatial resolution of microphone arrays with a given number of transducers. In this paper...

  18. Beamforming with a circular microphone array for localization of environmental noise sources

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Jacobsen, Finn; Fernandez Grande, Efren

    2010-01-01

    It is often enough to localize environmental sources of noise from different directions in a plane. This can be accomplished with a circular microphone array, which can be designed to have practically the same resolution over 360. The microphones can be suspended in free space or they can...

  19. Beamforming with a circular microphone array for localization of environmental sources of noise

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Jacobsen, Finn; Fernandez Grande, Efren

    2010-01-01

    It is often enough to localize environmental sources of noise from different directions in a plane. This can be accomplished with a circular microphone array, which can be designed to have practically the same resolution over 360. The microphones can be suspended in free space or they can...

  20. 76 FR 68207 - Certain Silicon Microphone Packages and Products Containing the Same; Determination To Rescind in...

    Science.gov (United States)

    2011-11-03

    ...] [FR Doc No: 2011-28488] INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-720] Certain Silicon... importation, or the sale within the United States after importation of certain silicon microphone packages and...'') prohibiting the unlicensed entry into the United States of MemsTech silicon microphone packages that infringe...

  1. MEMS Microphone Array Sensor for Air-Coupled Impact-Echo.

    Science.gov (United States)

    Groschup, Robin; Grosse, Christian U

    2015-06-25

    Impact-Echo (IE) is a nondestructive testing technique for plate like concrete structures. We propose a new sensor concept for air-coupled IE measurements. By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved. The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation. The proposed sensing strategy is justified with findings from numerical simulations, showing that the IE resonance in plate like structures causes coherent surface displacements on the specimen under test in an area around the impact location. Therefore, by placing several MEMS microphones on a sensor array board, the IE resonance is easier to be identified in the recorded spectra than with single point microphones or contact type transducers. A comparative measurement between the array sensor, a conventional accelerometer and a measurement microphone clearly shows the suitability of MEMS type microphones and the advantages of using these microphones in an array arrangement for IE. The MEMS microphone array will make air-coupled IE measurements faster and more reliable.

  2. Precision Measurements of Wind Turbine Noise using a Large Aperture Microphone Array

    DEFF Research Database (Denmark)

    Bradley, Stuart; Mikkelsen, Torben Krogh; Hünerbein, Sabine Von

    2016-01-01

    Experiments are described with a large microphone array (40 m scale) recording wind turbine noise. The array comprised 42 purpose-designed low-noise microphones simultaneously sampled at 20 kHz. Very high quality, fast, meteorological profile data was available from nearby 80 m masts and from the...

  3. Numerical design and testing of a sound source for secondary calibration of microphones using the Boundary Element Method

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller; Barrera Figueroa, Salvador

    2009-01-01

    Secondary calibration of microphones in free field is performed by placing the microphone under calibration in an anechoic chamber with a sound source, and exposing it to a controlled sound field. A calibrated microphone is also measured as a reference. While the two measurements are usually made...

  4. A practical implementation of microphone free-field comparison calibration according to the standard IEC 61094-8

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Torras Rosell, Antoni; Rasmussen, Knud

    2012-01-01

    An international standard concerned with the calibration of microphones in a free field by comparison has recently been published. The standard contemplates two main calibration methodologies for determining the sensitivity of a microphone under test when compared against a reference microphone. ...

  5. Systematic text condensation

    DEFF Research Database (Denmark)

    Malterud, Kirsti

    2012-01-01

    To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies.......To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies....

  6. Chromosome condensation and segmentation

    International Nuclear Information System (INIS)

    Viegas-Pequignot, E.M.

    1981-01-01

    Some aspects of chromosome condensation in mammalians -humans especially- were studied by means of cytogenetic techniques of chromosome banding. Two further approaches were adopted: a study of normal condensation as early as prophase, and an analysis of chromosome segmentation induced by physical (temperature and γ-rays) or chemical agents (base analogues, antibiotics, ...) in order to show out the factors liable to affect condensation. Here 'segmentation' means an abnormal chromosome condensation appearing systematically and being reproducible. The study of normal condensation was made possible by the development of a technique based on cell synchronization by thymidine and giving prophasic and prometaphasic cells. Besides, the possibility of inducing R-banding segmentations on these cells by BrdU (5-bromodeoxyuridine) allowed a much finer analysis of karyotypes. Another technique was developed using 5-ACR (5-azacytidine), it allowed to induce a segmentation similar to the one obtained using BrdU and identify heterochromatic areas rich in G-C bases pairs [fr

  7. Condensation in complex geometries

    International Nuclear Information System (INIS)

    Lauro, F.

    1975-01-01

    A mathematical evaluation of the condensation exchange coefficient can only succeds for well specified cases: small upright or inclined plates, horizontal tubes, small height vertical tubes. Among the main hypotheses accounted for this mathematical development in the case of the condensate, a laminar flow and uniform surface temperature are always considered. In practice certain shapes of surfaces significantly increase the heat transfer during the vapor condensation on a surface wet by the condensate. Such surfaces are rough surfaces such as the condensate is submitted to surface tension effects, negligeable for plane or large curvature surfaces, and the nature of the material may play an important role (temperature gradients). Results from tests on tubes with special shapes, performed in France or out of France, are given [fr

  8. Quartet condensation of fermions.

    Science.gov (United States)

    Talukdar, Aseem; Ma, Michael; Zhang, Fu-Chun

    2007-10-01

    We investigate quartet condensation in fermion systems with four internal states. This is the generalization of the well known BCS superconductor formed by Cooper pair (CP) condensation. Physical examples include spin-3/2 fermionic atoms, bi-layered systems with electrons and holes, quadra-layer spin polarized electron hole system, and two band electronic system. We derive the Landau Ginzberg (LG) free energy for such system in terms of the CP amplitudes. The LG free energy is found to contain attractive interactions among different types of CP's. This will allow them to form bound states of CP's called Cooper quartets (CQ). Using a variational calculation based on the Bogoliubov inequality, we find that CQ condensation may be favored over pair condensation at low temperature. We also study the pairing structures in such systems when pair condensation is preferred.

  9. Source Coding for Wireless Distributed Microphones in Reverberant Environments

    DEFF Research Database (Denmark)

    Zahedi, Adel

    2016-01-01

    's recording. This means that ignoring this correlation will be a waste of the scarce power and bandwidth resources. In this thesis, we study both information-theoretic and audio coding aspects of the coding problem in the above-mentioned framework. We formulate rate-distortion problems which take into account...... on the performance of the audio coding system. We derive explicit formulas for the rate-distortion functions, and design coding schemes that asymptotically achieve the performance bounds. We justify the Gaussianity assumption by showing that the results will still be relevant for non-Gaussian sources including audio...... for the transmitting microphone to reduce the rate by using distributed source coding. Within this framework, we apply our coding schemes to Gaussian signals as well as audio measurements and compare the rate-distortion performances for distributed and non-distributed source coding scenarios. We also compare...

  10. Regularised reconstruction of sound fields with a spherical microphone array

    DEFF Research Database (Denmark)

    Granados Corsellas, Alba; Jacobsen, Finn; Fernandez Grande, Efren

    2013-01-01

    Spherical near field acoustic holography with microphones mounted on a rigid spherical surface is used to reconstruct the incident sound field. However, reconstruction outside the sphere is an ill-posed inverse problem, and since this is very sensitive to the measurement noise, straightforward...... implementation might lead to disastrous reconstructions. A large number of regularisation tools based on singular value decomposition are available, and it has been found that the acoustic holography problem for certain geometries can be formulated in such a way that similarities to singular value decomposition...... become apparent. Hence, a number of regularisation methods, including truncated singular value decomposition, standard Tikhonov, constrained Tikhonov, iterative Tikhonov, Landweber and Rutishauser, have been adapted for spherical near field acoustic holography. The accuracy of the methods is examined...

  11. Plane-wave decomposition by spherical-convolution microphone array

    Science.gov (United States)

    Rafaely, Boaz; Park, Munhum

    2004-05-01

    Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.

  12. Automatic Detection of Whole Night Snoring Events Using Non-Contact Microphone

    Science.gov (United States)

    Dafna, Eliran; Tarasiuk, Ariel; Zigel, Yaniv

    2013-01-01

    Objective Although awareness of sleep disorders is increasing, limited information is available on whole night detection of snoring. Our study aimed to develop and validate a robust, high performance, and sensitive whole-night snore detector based on non-contact technology. Design Sounds during polysomnography (PSG) were recorded using a directional condenser microphone placed 1 m above the bed. An AdaBoost classifier was trained and validated on manually labeled snoring and non-snoring acoustic events. Patients Sixty-seven subjects (age 52.5±13.5 years, BMI 30.8±4.7 kg/m2, m/f 40/27) referred for PSG for obstructive sleep apnea diagnoses were prospectively and consecutively recruited. Twenty-five subjects were used for the design study; the validation study was blindly performed on the remaining forty-two subjects. Measurements and Results To train the proposed sound detector, >76,600 acoustic episodes collected in the design study were manually classified by three scorers into snore and non-snore episodes (e.g., bedding noise, coughing, environmental). A feature selection process was applied to select the most discriminative features extracted from time and spectral domains. The average snore/non-snore detection rate (accuracy) for the design group was 98.4% based on a ten-fold cross-validation technique. When tested on the validation group, the average detection rate was 98.2% with sensitivity of 98.0% (snore as a snore) and specificity of 98.3% (noise as noise). Conclusions Audio-based features extracted from time and spectral domains can accurately discriminate between snore and non-snore acoustic events. This audio analysis approach enables detection and analysis of snoring sounds from a full night in order to produce quantified measures for objective follow-up of patients. PMID:24391903

  13. Automatic detection of whole night snoring events using non-contact microphone.

    Directory of Open Access Journals (Sweden)

    Eliran Dafna

    Full Text Available OBJECTIVE: Although awareness of sleep disorders is increasing, limited information is available on whole night detection of snoring. Our study aimed to develop and validate a robust, high performance, and sensitive whole-night snore detector based on non-contact technology. DESIGN: Sounds during polysomnography (PSG were recorded using a directional condenser microphone placed 1 m above the bed. An AdaBoost classifier was trained and validated on manually labeled snoring and non-snoring acoustic events. PATIENTS: Sixty-seven subjects (age 52.5 ± 13.5 years, BMI 30.8 ± 4.7 kg/m(2, m/f 40/27 referred for PSG for obstructive sleep apnea diagnoses were prospectively and consecutively recruited. Twenty-five subjects were used for the design study; the validation study was blindly performed on the remaining forty-two subjects. MEASUREMENTS AND RESULTS: To train the proposed sound detector, >76,600 acoustic episodes collected in the design study were manually classified by three scorers into snore and non-snore episodes (e.g., bedding noise, coughing, environmental. A feature selection process was applied to select the most discriminative features extracted from time and spectral domains. The average snore/non-snore detection rate (accuracy for the design group was 98.4% based on a ten-fold cross-validation technique. When tested on the validation group, the average detection rate was 98.2% with sensitivity of 98.0% (snore as a snore and specificity of 98.3% (noise as noise. CONCLUSIONS: Audio-based features extracted from time and spectral domains can accurately discriminate between snore and non-snore acoustic events. This audio analysis approach enables detection and analysis of snoring sounds from a full night in order to produce quantified measures for objective follow-up of patients.

  14. Automatic detection of whole night snoring events using non-contact microphone.

    Science.gov (United States)

    Dafna, Eliran; Tarasiuk, Ariel; Zigel, Yaniv

    2013-01-01

    Although awareness of sleep disorders is increasing, limited information is available on whole night detection of snoring. Our study aimed to develop and validate a robust, high performance, and sensitive whole-night snore detector based on non-contact technology. Sounds during polysomnography (PSG) were recorded using a directional condenser microphone placed 1 m above the bed. An AdaBoost classifier was trained and validated on manually labeled snoring and non-snoring acoustic events. Sixty-seven subjects (age 52.5 ± 13.5 years, BMI 30.8 ± 4.7 kg/m(2), m/f 40/27) referred for PSG for obstructive sleep apnea diagnoses were prospectively and consecutively recruited. Twenty-five subjects were used for the design study; the validation study was blindly performed on the remaining forty-two subjects. To train the proposed sound detector, >76,600 acoustic episodes collected in the design study were manually classified by three scorers into snore and non-snore episodes (e.g., bedding noise, coughing, environmental). A feature selection process was applied to select the most discriminative features extracted from time and spectral domains. The average snore/non-snore detection rate (accuracy) for the design group was 98.4% based on a ten-fold cross-validation technique. When tested on the validation group, the average detection rate was 98.2% with sensitivity of 98.0% (snore as a snore) and specificity of 98.3% (noise as noise). Audio-based features extracted from time and spectral domains can accurately discriminate between snore and non-snore acoustic events. This audio analysis approach enables detection and analysis of snoring sounds from a full night in order to produce quantified measures for objective follow-up of patients.

  15. The impact of the microphone position on the frequency analysis of snoring sounds.

    Science.gov (United States)

    Herzog, Michael; Kühnel, Thomas; Bremert, Thomas; Herzog, Beatrice; Hosemann, Werner; Kaftan, Holger

    2009-08-01

    Frequency analysis of snoring sounds has been reported as a diagnostic tool to differentiate between different sources of snoring. Several studies have been published presenting diverging results of the frequency analyses of snoring sounds. Depending on the position of the used microphones, the results of the frequency analysis of snoring sounds vary. The present study investigated the influence of different microphone positions on the outcome of the frequency analysis of snoring sounds. Nocturnal snoring was recorded simultaneously at six positions (air-coupled: 30 cm middle, 100 cm middle, 30 cm lateral to both sides of the patients' head; body contact: neck and parasternal) in five patients. The used microphones had a flat frequency response and a similar frequency range (10/40 Hz-18 kHz). Frequency analysis was performed by fast Fourier transformation and frequency bands as well as peak intensities (Peaks 1-5) were detected. Air-coupled microphones presented a wider frequency range (60 Hz-10 kHz) compared to contact microphones. The contact microphone at cervical position presented a cut off at frequencies above 300 Hz, whereas the contact microphone at parasternal position revealed a cut off above 100 Hz. On an exemplary base, the study demonstrates that frequencies above 1,000 Hz do appear in complex snoring patterns, and it is emphasised that high frequencies are imported for the interpretation of snoring sounds with respect to the identification of the source of snoring. Contact microphones might be used in screening devices, but for a natural analysis of snoring sounds the use of air-coupled microphones is indispensable.

  16. Physics of condensed matter

    CERN Document Server

    Misra, Prasanta K

    2012-01-01

    Physics of Condensed Matter is designed for a two-semester graduate course on condensed matter physics for students in physics and materials science. While the book offers fundamental ideas and topic areas of condensed matter physics, it also includes many recent topics of interest on which graduate students may choose to do further research. The text can also be used as a one-semester course for advanced undergraduate majors in physics, materials science, solid state chemistry, and electrical engineering, because it offers a breadth of topics applicable to these majors. The book be

  17. Acoustic Feedback and Echo Cancellation Strategies for Multiple-Microphone and Single-Loudspeaker Systems

    DEFF Research Database (Denmark)

    Guo, Meng; Elmedyb, Thomas Bo; Jensen, Søren Holdt

    2011-01-01

    Acoustic feedback/echo cancellation in a multiple-microphone and single-loudspeaker system is often carried out using a cancellation filter for each microphone channel, and the filters are adaptively estimated, independently of each other. In this work, we consider another strategy by estimating...... all the cancellation filters jointly and in this way exploit information from all microphone channels. We determine the statistical system behavior for the joint estimation strategy in terms of the convergence rate and steady-state behavior across time and frequency. We assess if an improved...

  18. Emergent electromechanical coupling of electrets and some exact relations — The effective properties of soft materials with embedded external charges and dipoles

    Science.gov (United States)

    Liu, Liping; Sharma, Pradeep

    2018-03-01

    Soft robotics, energy harvesting, large-deformation sensing and actuation, are just some of the applications that can be enabled by soft dielectrics that demonstrate substantive electromechanical coupling. Most soft dielectrics including elastomers, however, are not piezoelectric and rely on the universally present electrostriction and the Maxwell stress effect to enable the aforementioned applications. Electrostriction is a one-way electromechanical coupling and the induced elastic strain scales as (∝E2) upon the application of an electric field, E. The quadratic dependence of electrostriction on the electric field and the one-way coupling imply that, (i) A rather high voltage is required to induce appreciable strain, (ii) reversal of an applied bias will not reverse the sign of the deformation, and (iii) since it is a one-way coupling i.e. electrical stimuli may cause mechanical deformation but electricity cannot be generated by mechanical deformation, prospects for energy harvesting are rather difficult. An interesting approach for realizing an apparent piezoelectric-like behavior is to dope soft dielectrics with immobile charges and dipoles. Such materials, called electrets, are rather unique composites where a secondary material (in principle) is not necessary. Both experiments and supporting theoretical work have shown that soft electrets can exhibit a very large electromechanical coupling including a piezoelectric-like response. In this work, we present a homogenization theory for electret materials and provide, in addition to several general results, variational bounds and closed-form expressions for specific microstructures such as laminates and ellipsoidal inclusions. While we consider the nonlinear coupled problem, to make analytical progress, we work within the small-deformation setting. The specific conditions necessary to obtain a piezoelectric-like response and enhanced electrostriction are highlighted. There are very few universal, microstructure

  19. Condensation in Microchannels

    National Research Council Canada - National Science Library

    Ameel, Timothy

    1999-01-01

    .... Evaporators and condensers for meso-scale energy systems will most likely be constructed of microchannels due to the microfabrication constraints that limit most structures to two-dimensional planar geometries...

  20. Comparison among the scintillation and electrets techniques for emission of alpha radiation; Comparacion de las tecnicas de centelleo y electretos para emision de radiacion alfa

    Energy Technology Data Exchange (ETDEWEB)

    Moreno y Moreno, A. [Deparatmento de Apoyo en Ciencias Aplicadas, BUAP, 72000 Puebla (Mexico); Gammage, R.B. [Oak Ridge National Laboratory (United States)

    2005-07-01

    A comparison of the scintillation and of electret techniques for measurement of Uranium, Plutonium and transuranic elements in low level radioactivity is presented in this work. The samples of material to measure were obtained by the Research Department of the Oak Ridge National Laboratory (ORNL) of contaminated soils by radioactive material of plutonium and other transuranic elements. The samples in both techniques were measured to infinite thickness. The electret E - PERM of Rad Elec. Inc.; it was the available selected detector in 1993 and the measures with this technique were carried out by the Dr. R. B. Gammage and the Dr. K. E. Meyer of the Health and Safety Research Division of ORNL. The scintillation technique for measurement of the samples up mentioned it was carried out by the Dr. Augusto Moreno y Moreno in the facilities of DOSAR of ORNL. The comparative results of the two techniques agree just as it is shown in this work; but the scintillation technique offers the advantage of a considerable reduction of the exposure time and reading of the samples - electret, if it is compared with the immediate measurement of the scintillation technique that is described in this work. (Author)

  1. Recognition of In-Ear Microphone Speech Data Using Multi-Layer Neural Networks

    National Research Council Canada - National Science Library

    Bulbuller, Gokhan

    2006-01-01

    .... In this study, a speech recognition system is presented, specifically an isolated word recognizer which uses speech collected from the external auditory canals of the subjects via an in-ear microphone...

  2. Design of UAV-Embedded Microphone Array System for Sound Source Localization in Outdoor Environments.

    Science.gov (United States)

    Hoshiba, Kotaro; Washizaki, Kai; Wakabayashi, Mizuho; Ishiki, Takahiro; Kumon, Makoto; Bando, Yoshiaki; Gabriel, Daniel; Nakadai, Kazuhiro; Okuno, Hiroshi G

    2017-11-03

    In search and rescue activities, unmanned aerial vehicles (UAV) should exploit sound information to compensate for poor visual information. This paper describes the design and implementation of a UAV-embedded microphone array system for sound source localization in outdoor environments. Four critical development problems included water-resistance of the microphone array, efficiency in assembling, reliability of wireless communication, and sufficiency of visualization tools for operators. To solve these problems, we developed a spherical microphone array system (SMAS) consisting of a microphone array, a stable wireless network communication system, and intuitive visualization tools. The performance of SMAS was evaluated with simulated data and a demonstration in the field. Results confirmed that the SMAS provides highly accurate localization, water resistance, prompt assembly, stable wireless communication, and intuitive information for observers and operators.

  3. Sound-field reconstruction performance of a mixed-order Ambisonics microphone array

    DEFF Research Database (Denmark)

    Marschall, Marton; Chang, Jiho

    2013-01-01

    Recently, there has been increasing interest in using spherical microphone arrays for spatial audio recordings. Accurate recordings are important for a range of applications, from virtual sound environments for hearing research through to the evaluation of communication devices, such as hearing...... instruments and mobile phones. Previously, a mixed-order Ambisonics (MOA) approach was proposed to improve the horizontal spatial resolution of spherical arrays. This was achieved by increasing the number of microphones near the horizontal plane while keeping the total number of transducers fixed...... microphone were used to simulate self-noise, sensitivity, and phase response variations between the microphones. To quantify the reconstruction error and the "sweet area" as a function of source elevation, the reconstructed sound field based on a simulated array measurement was compared to the reference...

  4. 78 FR 21977 - Certain Silicon Microphone Packages and Products Containing the Same; Commission Determination...

    Science.gov (United States)

    2013-04-12

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Silicon Microphone Packages and Products Containing the Same; Commission Determination Not To Review an Initial Determination Terminating Investigation Based on a Settlement Agreement...

  5. Design Considerations When Accelerating an FPGA-Based Digital Microphone Array for Sound-Source Localization

    Directory of Open Access Journals (Sweden)

    Bruno da Silva

    2017-01-01

    Full Text Available The use of microphone arrays for sound-source localization is a well-researched topic. The response of such sensor arrays is dependent on the quantity of microphones operating on the array. A higher number of microphones, however, increase the computational demand, making real-time response challenging. In this paper, we present a Filter-and-Sum based architecture and several acceleration techniques to provide accurate sound-source localization in real-time. Experiments demonstrate how an accurate sound-source localization is obtained in a couple of milliseconds, independently of the number of microphones. Finally, we also propose different strategies to further accelerate the sound-source localization while offering increased angular resolution.

  6. Design of UAV-Embedded Microphone Array System for Sound Source Localization in Outdoor Environments †

    Science.gov (United States)

    Hoshiba, Kotaro; Washizaki, Kai; Wakabayashi, Mizuho; Ishiki, Takahiro; Bando, Yoshiaki; Gabriel, Daniel; Nakadai, Kazuhiro; Okuno, Hiroshi G.

    2017-01-01

    In search and rescue activities, unmanned aerial vehicles (UAV) should exploit sound information to compensate for poor visual information. This paper describes the design and implementation of a UAV-embedded microphone array system for sound source localization in outdoor environments. Four critical development problems included water-resistance of the microphone array, efficiency in assembling, reliability of wireless communication, and sufficiency of visualization tools for operators. To solve these problems, we developed a spherical microphone array system (SMAS) consisting of a microphone array, a stable wireless network communication system, and intuitive visualization tools. The performance of SMAS was evaluated with simulated data and a demonstration in the field. Results confirmed that the SMAS provides highly accurate localization, water resistance, prompt assembly, stable wireless communication, and intuitive information for observers and operators. PMID:29099790

  7. Design of UAV-Embedded Microphone Array System for Sound Source Localization in Outdoor Environments

    Directory of Open Access Journals (Sweden)

    Kotaro Hoshiba

    2017-11-01

    Full Text Available In search and rescue activities, unmanned aerial vehicles (UAV should exploit sound information to compensate for poor visual information. This paper describes the design and implementation of a UAV-embedded microphone array system for sound source localization in outdoor environments. Four critical development problems included water-resistance of the microphone array, efficiency in assembling, reliability of wireless communication, and sufficiency of visualization tools for operators. To solve these problems, we developed a spherical microphone array system (SMAS consisting of a microphone array, a stable wireless network communication system, and intuitive visualization tools. The performance of SMAS was evaluated with simulated data and a demonstration in the field. Results confirmed that the SMAS provides highly accurate localization, water resistance, prompt assembly, stable wireless communication, and intuitive information for observers and operators.

  8. Speech perception comparisons using an implanted and an external microphone in existing cochlear implant users.

    Science.gov (United States)

    Jenkins, Herman A; Uhler, Kristin

    2012-01-01

    To compare the speech understanding abilities of cochlear implant listeners using 2 microphone technologies, the Otologics fully implantable Carina and the Cochlear Freedom microphones. Feasibility study using direct comparison of the 2 microphones, nonrandomized and nonblinded within case studies. Tertiary referral center hospital outpatient clinic. Four subjects with greater than 1 year of unilateral listening experience with the Freedom Cochlear Implant and a CNC word score higher than 40%. A Carina microphone coupled to a percutaneous plug was implanted on the ipsilateral side of the cochlear implant. Two months were allowed for healing before connecting to the Carina microphone. The percutaneous plug was connected to a body worn external processor with output leads inserted into the auxiliary port of the Freedom processor. Subjects were instructed to use each of the 2 microphones for half of their daily implant use. Aided pure tone thresholds, consonant-nucleus-consonant (CNC), Bamford-Kowel-Bench Speech in Noise test (BKN-SIN), and Abbreviated Profile of Hearing Aid Benefit. All subjects had sound perceptions using both microphones. The loudness and quality of the sound was judged to be poorer with the Carina in the first 2 subjects. The latter 2 demonstrated essential equivalence in the second two listeners, with the exception of the Abbreviated Profile of Hearing Aid Benefit reporting greater percentage of problems for the Carina in the background noise situation for subject 0011-003PP. CNC word scores were better with the Freedom than the Carina in all 4 subjects. The latter 2 showed improved speech perception abilities with the Carina, compared with the first 2. The BKB-SIN showed consistently better results with the Freedom in noise. Early observations indicate that it is potentially feasible to use the fully implanted Carina microphone with the Freedom Cochlear Implant. The authors would anticipate that outcomes would improve as more knowledge is gained

  9. Implementation of a Virtual Microphone Array to Obtain High Resolution Acoustic Images

    OpenAIRE

    Izquierdo, Alberto; Villacorta, Juan J.; del Val, Lara; Suárez, Luis; Suárez, David

    2017-01-01

    Using arrays with digital MEMS (Micro-Electro-Mechanical System) microphones and FPGA-based (Field Programmable Gate Array) acquisition/processing systems allows building systems with hundreds of sensors at a reduced cost. The problem arises when systems with thousands of sensors are needed. This work analyzes the implementation and performance of a virtual array with 6400 (80 × 80) MEMS microphones. This virtual array is implemented by changing the position of a physical array of 64 (8 × 8) ...

  10. Hollow core MOEMS Bragg grating microphone for distributed and remote sensing

    DEFF Research Database (Denmark)

    Reck, Kasper; Østergaard, Christian; Thomsen, Erik Vilain

    2011-01-01

    We present the design and fabrication of a completely new high sensitivity all-optical frequency modulated MOEMS microphone for distributed and remote sensing applications. Due to immunity to electromagnetic interference, no parasitic capacitances and easy wavelength division multiplexing (WDM) c...... most suitable for high stress sensing, e.g. in structural health monitoring. The MOEMS microphone presented here has a calculated static pressure sensitivity approximately 104 times larger than conventional FBGs [2,3]....

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

    Science.gov (United States)

    Manz, Johannes; Dehe, Alfons; Schrag, Gabriele

    2017-05-01

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

  12. Real-time Identification of Respiratory Movements through a Microphone

    Directory of Open Access Journals (Sweden)

    Juan CASTRO

    2015-05-01

    Full Text Available This work presents a software application to identify, in real time, the respiratory movements -inspiration and expiration- through a microphone. The application, which has been developed in Matlab and named ASBSLAB for the GUI version and ASBSLABCONSOLE for the command-line version, is the result of a research and experimentation process. A total of 48 minutes of breathing movements from four subjects was recorded and 18 acoustic features were extracted to generate the data model. A first level of identification, based on the classification of tiny audio segments, was designed using kNN supervised method. The second level of identification implements a state machine that takes the results ordered in the time from kNN as input and identifies the whole respiratory movement, achieving a level of positive identifications above 95%. As computation time is a handicap, the application let the user choose easily the sample rate, the audio segment size and the set of acoustic features to use in the identification process. In addition, based on the number of features selected, this works suggests those that achieve best results.

  13. Condensate feeding system

    International Nuclear Information System (INIS)

    Iwami, Hiroshi.

    1981-01-01

    Purpose: To control the dissolved oxygen concentration in water of a condensate feeding system to a desired level. Constitution: Coolant is fed to a nuclear reactor through a route from the steam exit of the reactor and by way of turbine, turbine condensator, condensate pump, condensate desalinator, feedwater heater and feed pump. Steam extraction lines are branched from the turbines, and pipeways are further branched from the steam extraction lines for feeding steam by way of extraction steam injection valves to steam-water mixers disposed on the upstream of the feedwater heater. On the downstream of the feedwater heater, is provided a dissolved oxygen concentration meter, the indication value of which controls the opening degree of the steam injection valves which, in turn, controls the opening degree of the steam feed valves for the feedwater heater to adjust the amount for the injection steams. Accordingly, the dissolved oxygen concentration in the water of the condensate feeding system can be controlled by the inclusion of steams with high dissolved oxygen concentration into the feedwater system from the turbine steam extraction lines by way of the mixers. (Furukawa, Y.)

  14. Filter quality of electret masks in filtering 14.6–594 nm aerosol particles: Effects of five decontamination methods

    Science.gov (United States)

    Lin, Tzu-Hsien; Chen, Chih-Chieh; Kuo, Chung-Wen

    2017-01-01

    This study investigates the effects of five decontamination methods on the filter quality (qf) of three commercially available electret masks—N95, Gauze and Spunlace nonwoven masks. Newly developed evaluation methods, the overall filter quality (qf,o) and the qf ratio were applied to evaluate the effectiveness of decontamination methods for respirators. A scanning mobility particle sizer is utilized to measure the concentration of polydispersed particles with diameter 14.6–594 nm. The penetration of particles and pressure drop (Δp) through the mask are used to determine qf and qf,o. Experimental results reveal that the most penetrating particle size (MPS) for the pre-decontaminated N95, Gauze and Spunlace masks were 118 nm, 461 nm and 279 nm, respectively, and the respective penetration rates were 2.6%, 23.2% and 70.0%. The Δp through the pretreated N95 masks was 9.2 mm H2O at the breathing flow rate of heavy-duty workers, exceeding the Δp values obtained through Gauze and Spunlace masks. Decontamination increased the sizes of the most penetrating particles, changing the qf values of all of the masks: qf fell as particle size increased because the penetration increased. Bleach increased the Δp of N95, but destroyed the Gauze mask. However, the use of an autoclave reduces the Δp values of both the N95 and the Gauze mask. Neither the rice cooker nor ethanol altered the Δp of the Gauze mask. Chemical decontamination methods reduced the qf,o values for the three electret masks. The value of qf,o for PM0.1 exceeded that for PM0.1–0.6, because particles smaller than 100 nm had lower penetration, resulting in a better qf for a given pressure drop. The values of qf,o, particularly for PM0.1, reveal that for the tested treatments and masks, physical decontamination methods are less destructive to the filter than chemical methods. Nevertheless, when purchasing new or reusing FFRs, penetration should be regarded as the priority. PMID:29023492

  15. Filter quality of electret masks in filtering 14.6-594 nm aerosol particles: Effects of five decontamination methods.

    Directory of Open Access Journals (Sweden)

    Tzu-Hsien Lin

    Full Text Available This study investigates the effects of five decontamination methods on the filter quality (qf of three commercially available electret masks-N95, Gauze and Spunlace nonwoven masks. Newly developed evaluation methods, the overall filter quality (qf,o and the qf ratio were applied to evaluate the effectiveness of decontamination methods for respirators. A scanning mobility particle sizer is utilized to measure the concentration of polydispersed particles with diameter 14.6-594 nm. The penetration of particles and pressure drop (Δp through the mask are used to determine qf and qf,o. Experimental results reveal that the most penetrating particle size (MPS for the pre-decontaminated N95, Gauze and Spunlace masks were 118 nm, 461 nm and 279 nm, respectively, and the respective penetration rates were 2.6%, 23.2% and 70.0%. The Δp through the pretreated N95 masks was 9.2 mm H2O at the breathing flow rate of heavy-duty workers, exceeding the Δp values obtained through Gauze and Spunlace masks. Decontamination increased the sizes of the most penetrating particles, changing the qf values of all of the masks: qf fell as particle size increased because the penetration increased. Bleach increased the Δp of N95, but destroyed the Gauze mask. However, the use of an autoclave reduces the Δp values of both the N95 and the Gauze mask. Neither the rice cooker nor ethanol altered the Δp of the Gauze mask. Chemical decontamination methods reduced the qf,o values for the three electret masks. The value of qf,o for PM0.1 exceeded that for PM0.1-0.6, because particles smaller than 100 nm had lower penetration, resulting in a better qf for a given pressure drop. The values of qf,o, particularly for PM0.1, reveal that for the tested treatments and masks, physical decontamination methods are less destructive to the filter than chemical methods. Nevertheless, when purchasing new or reusing FFRs, penetration should be regarded as the priority.

  16. Condensed matter physics

    CERN Document Server

    Isihara, A

    2007-01-01

    More than a graduate text and advanced research guide on condensed matter physics, this volume is useful to plasma physicists and polymer chemists, and their students. It emphasizes applications of statistical mechanics to a variety of systems in condensed matter physics rather than theoretical derivations of the principles of statistical mechanics and techniques. Isihara addresses a dozen different subjects in separate chapters, each designed to be directly accessible and used independently of previous chapters. Topics include simple liquids, electron systems and correlations, two-dimensional

  17. Characterization of microphones for snoring and breathing events analysis in mHealth.

    Science.gov (United States)

    Castillo, Yolanda; Camara, Miguel A; Blanco-Almazan, Dolores; Jane, Raimon

    2017-07-01

    Obstructive sleep apnea (OSA) is one of the most common sleep disorders, especially in elderly population. Despite its high prevalence and severe consequences, most patients remain undiagnosed due to serious limitations on the existing equipment. Efforts are being done to find cost-effective alternatives and mHealth solutions could play a key role. One promising approach in this context is the acoustic analysis of snoring. The sensor it requires is a microphone, which is widely available in different models and even integrated in smartphones. The objective of this work is to characterize and compare the responses of two commercial tracheal microphones and a mHealth-based microphone, as a proof-of-concept to evaluate their potential as sensors for OSA detection. To do that, we designed an experimental protocol to study OSA-related events (breaths, snores and apneas) simulated by 4 subjects. Test signals were simultaneously recorded with different microphones and posteriorly processed and analyzed. We accurately characterized the frequency response of the two commercial microphones, finding that one of them was too restrictive (bandwidth 50-250 Hz) and thus not suitable as snoring sensor for high-frequency acoustic analysis. Regarding smartphones, we studied the Samsung Galaxy S5 microphone. We found that, when located over the thorax, it provided quality signals comparable to those of tracheal microphones, with a broader frequency response. Further work is required, but this preliminary study suggests that acoustic analysis of snoring through mHealth solutions can be a feasible alternative to screen and monitor OSA patients at home.

  18. A comparison of the Standing Wave and Two Microphone Methods in Measuring The Sound Absorption Coefficient of Wood

    OpenAIRE

    Kang, Chunwon; Matsumura, Junji; Oda, Kazuyuki

    2006-01-01

    To compare the standing wave method with two microphone transfer function method in the measuring the sound absorption properties of wood, we measured the sound absorption coefficients of beech wood experimentally in the frequency range of 50 to 1600 Hz by the standing wave method and two-microphone method. The sound absorption coefficient under a continuous frequency range can be estimated in a shorter time by the two microphone transfer function method than the standing wave method. There...

  19. Blind source separation and localization using microphone arrays

    Science.gov (United States)

    Sun, Longji

    The blind source separation and localization problem for audio signals is studied using microphone arrays. Pure delay mixtures of source signals typically encountered in outdoor environments are considered. Our proposed approach utilizes the subspace methods, including multiple signal classification (MUSIC) and estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithms, to estimate the directions of arrival (DOAs) of the sources from the collected mixtures. Since audio signals are generally considered broadband, the DOA estimates at frequencies with the large sum of squared amplitude values are combined to obtain the final DOA estimates. Using the estimated DOAs, the corresponding mixing and demixing matrices are computed, and the source signals are recovered using the inverse short time Fourier transform. Subspace methods take advantage of the spatial covariance matrix of the collected mixtures to achieve robustness to noise. While the subspace methods have been studied for localizing radio frequency signals, audio signals have their special properties. For instance, they are nonstationary, naturally broadband and analog. All of these make the separation and localization for the audio signals more challenging. Moreover, our algorithm is essentially equivalent to the beamforming technique, which suppresses the signals in unwanted directions and only recovers the signals in the estimated DOAs. Several crucial issues related to our algorithm and their solutions have been discussed, including source number estimation, spatial aliasing, artifact filtering, different ways of mixture generation, and source coordinate estimation using multiple arrays. Additionally, comprehensive simulations and experiments have been conducted to examine various aspects of the algorithm. Unlike the existing blind source separation and localization methods, which are generally time consuming, our algorithm needs signal mixtures of only a short duration and

  20. Condensed matter physics

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    The condensed matter physics research in the Physics Department of Risoe National Laboratory is predominantly experimental utilising diffraction of neutrons and x-rays. The research topics range from studies of structure, excitations and phase transitions in model systems to studies of ion transport, texture and recrystallization kinetics with a more applied nature. (author)

  1. Modular invariant gaugino condensation

    Energy Technology Data Exchange (ETDEWEB)

    Gaillard, M.K.

    1991-05-09

    The construction of effective supergravity lagrangians for gaugino condensation is reviewed and recent results are presented that are consistent with modular invariance and yield a positive definite potential of the noscale type. Possible implications for phenomenology are briefly discussed. 29 refs.

  2. Bose-Einstein Condensation

    Indian Academy of Sciences (India)

    have quoted, London noted that at the density of liquid helium, the temperature for Bose-Einstein condensation of an ideal gas would be about three degrees above absolute zero.4 Liquid helium shows new properties below 2.1 degrees Kelvin [3]. London boldly suggested that these new properties were a consequence of ...

  3. Bose-Einstein Condensation

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 12. Bose-Einstein Condensation - Birds of a Feather Flock Together. Rajaram Nityananda. Volume 10 Issue 12 December 2005 pp 142-147. Fulltext. Click here to view fulltext PDF. Permanent link:

  4. Bose-Einstein Condensation

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 4. Bose–Einstein Condensation - Birds of a Feather Flock Together. Rajaram Nityananda. General Article Volume 5 Issue 4 April 2000 pp 46-51. Fulltext. Click here to view fulltext PDF. Permanent link:

  5. Bose-Einstein condensation

    Indian Academy of Sciences (India)

    Bose-Einstein Condensation. Vasant Natarajan is at the. Department of Physics,. Indian Institute of. Science. His current research involves trapping of atoms to carry out high precision tests of fundamental physics. He has earlier worked on high precision mass spectrom- etry and on the focussing of atomic beams by laser.

  6. Confinement contains condensates

    DEFF Research Database (Denmark)

    Brodsky, S. J.; Roberts, C. D.; Shrock, R.

    2012-01-01

    Dynamical chiral symmetry breaking and its connection to the generation of hadron masses has historically been viewed as a vacuum phenomenon. We argue that confinement makes such a position untenable. If quark-hadron duality is a reality in QCD, then condensates, those quantities that have common...... evidence and incidentally expose misconceptions in a recent Comment....

  7. Condensed matter physics

    International Nuclear Information System (INIS)

    1990-01-01

    This is a summary of condensed matter physics in Brazil. It discusses as well, the perspectives and financing evolved in this research area for the next decade. It is specially concerned with semiconductors, magnetic materials, superconductivity, polymers, glasses, crystals ceramics, statistical physics, magnetic resonance and Moessbauer spectroscopy. (A.C.A.S.)

  8. Electrons in Condensed Matter

    Indian Academy of Sciences (India)

    Electrons in Condensed Matter. T V Ramakrishnan. Introduction. A hundred years ago, J J Thomson tore light negatively charged particles out of many different kinds of atoms by subjecting them to strong electric fields in discharge tubes. He showed that the same particle (with identical charge e and charge to mass ratio ...

  9. Simple Simulations of DNA Condensation

    Energy Technology Data Exchange (ETDEWEB)

    STEVENS,MARK J.

    2000-07-12

    Molecular dynamics simulations of a simple, bead-spring model of semiflexible polyelectrolytes such as DNA are performed. All charges are explicitly treated. Starting from extended, noncondensed conformations, condensed structures form in the simulations with tetravalent or trivalent counterions. No condensates form or are stable for divalent counterions. The mechanism by which condensates form is described. Briefly, condensation occurs because electrostatic interactions dominate entropy, and the favored Coulombic structure is a charge ordered state. Condensation is a generic phenomena and occurs for a variety of polyelectrolyte parameters. Toroids and rods are the condensate structures. Toroids form preferentially when the molecular stiffness is sufficiently strong.

  10. Characteristics of Relocated Quiet Zones Using Virtual Microphone Algorithm in an Active Headrest System

    Directory of Open Access Journals (Sweden)

    Seokhoon Ryu

    2016-01-01

    Full Text Available This study displays theoretical and experimental investigation on the characteristics of the relocated zone of quiet by a virtual microphone (VM based filtered-x LMS (FxLMS algorithm which can be embedded in a real-time digital controller for an active headrest system. The attenuation changes at the relocated zones of quiet by the variation of the distance between the ear and the error microphone are mainly examined. An active headrest system was implemented for the control experiment at a chair and consists of two (left and right secondary loudspeakers, two error microphones, two observer microphones at ear positions in a HATS, and other electronics including a dSPACE 1401 controller. The VM based FxLMS algorithm achieved an attenuation of about 22 dB in the control experiment against a narrowband primary noise by the variation of the distance between the ear and the error microphone. The important factors for the algorithm are discussed as well.

  11. A nonlinear active noise control algorithm for virtual microphones controlling chaotic noise.

    Science.gov (United States)

    Das, Debi Prasad; Moreau, Danielle J; Cazzolato, Ben S

    2012-08-01

    In active noise control (ANC) systems, virtual microphones provide a means of projecting the zone of quiet away from the physical microphone to a remote location. To date, linear ANC algorithms, such as the filtered-x least mean square (FXLMS) algorithm, have been used with virtual sensing techniques. In this paper, a nonlinear ANC algorithm is developed for a virtual microphone by integrating the remote microphone technique with the filtered-s least mean square (FSLMS) algorithm. The proposed algorithm is evaluated experimentally in the cancellation of chaotic noise in a one-dimensional duct. The secondary paths evaluated experimentally exhibit non-minimum phase response and hence poor performance is obtained with the conventional FXLMS algorithm compared to the proposed FSLMS based algorithm. This is because the latter is capable of predicting the chaotic signal found in many physical processes responsible for noise. In addition, the proposed algorithm is shown to outperform the FXLMS based remote microphone technique under the causality constraint (when the propagation delay of the secondary path is greater than the primary path). A number of experimental results are presented in this paper to compare the performance of the FSLMS algorithm based virtual ANC algorithm with the FXLMS based virtual ANC algorithm.

  12. Influence of non condensable gases on condenser performance. Bibliographical study

    International Nuclear Information System (INIS)

    Phong, Vinh

    1970-09-01

    The author proposes a synthesis of a bibliographical study on condenser performance, and more particularly on the influence of non-condensables on these performance. He distinguishes experimental studies, and analytical or theoretical studies. As far as experimental studies are concerned, he discusses various factors: influence of the rate of non condensables and of scan rate, influence of condenser geometry, influence of the exchanged heat flow, influence of the operational pressure, empirical correlations. As far as analytical studies on the influence of non-condensables are concerned, the author discusses and comments diffusion laws, and some specific studies [fr

  13. Research Status of Evaporative Condenser

    Science.gov (United States)

    Wang, Feifei; Yang, Yongan

    2018-02-01

    Reducing energy consumption, saving water resources, recycling cool water are main directions of China’s development. Evaporative condenser using latent heat reduces water resources waste, with energy-saving advantages. This paper reviews the research status of evaporative condenser at home and abroad, and introduces the principle, classification, various influencing factors of evaporative condenser, and puts forward the future research direction.

  14. A study of airborne radon levels in Paarl houses (South Africa) and associated source terms, using electret ion chambers and gamma-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, R. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7537 (South Africa)], E-mail: rlindsay@uwc.ac.za; Newman, R.T. [Environmental Radioactivity Laboratory, Physics Group, iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa); Speelman, W.J. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7537 (South Africa)

    2008-11-15

    Indoor radon ({sup 222}Rn) concentrations were measured in Paarl homes by means of electret ion chambers. The concentrations varied between 28 and 465 Bq m{sup -3}. The average values (Bq m{sup -3}) found in houses on the west and east side of the Berg River, which bisects Paarl, were 132 ({+-}11) and 37 ({+-}3), respectively. Radiometric analyses of soils show that the mean {sup 226}Ra activity concentration is three times higher on the west than on the east side of the Berg River.

  15. Microphone directionality, pre-emphasis filter, and wind noise in cochlear implants.

    Science.gov (United States)

    Chung, King; McKibben, Nicholas

    2011-10-01

    Wind noise can be a nuisance or a debilitating masker for cochlear implant users in outdoor environments. Previous studies indicated that wind noise at the microphone/hearing aid output had high levels of low-frequency energy and the amount of noise generated is related to the microphone directionality. Currently, cochlear implants only offer either directional microphones or omnidirectional microphones for users at-large. As all cochlear implants utilize pre-emphasis filters to reduce low-frequency energy before the signal is encoded, effective wind noise reduction algorithms for hearing aids might not be applicable for cochlear implants. The purposes of this study were to investigate the effect of microphone directionality on speech recognition and perceived sound quality of cochlear implant users in wind noise and to derive effective wind noise reduction strategies for cochlear implants. A repeated-measure design was used to examine the effects of spectral and temporal masking created by wind noise recorded through directional and omnidirectional microphones and the effects of pre-emphasis filters on cochlear implant performance. A digital hearing aid was programmed to have linear amplification and relatively flat in-situ frequency responses for the directional and omnidirectional modes. The hearing aid output was then recorded from 0 to 360° at flow velocities of 4.5 and 13.5 m/sec in a quiet wind tunnel. Sixteen postlingually deafened adult cochlear implant listeners who reported to be able to communicate on the phone with friends and family without text messages participated in the study. Cochlear implant users listened to speech in wind noise recorded at locations that the directional and omnidirectional microphones yielded the lowest noise levels. Cochlear implant listeners repeated the sentences and rated the sound quality of the testing materials. Spectral and temporal characteristics of flow noise, as well as speech and/or noise characteristics before

  16. Recovery of condensate water quality in power generator's surface condenser

    Science.gov (United States)

    Kurniawan, Lilik Adib

    2017-03-01

    In PT Badak NGL Plant, steam turbines are used to drive major power generators, compressors, and pumps. Steam exiting the turbines is condensed in surface condensers to be returned to boilers. Therefore, surface condenser performance and quality of condensate water are very important. One of the recent problem was caused by the leak of a surface condenser of Steam Turbine Power Generator. Thesteam turbine was overhauled, leaving the surface condenser idle and exposed to air for more than 1.5 years. Sea water ingress due to tube leaks worsens the corrosionof the condenser shell. The combination of mineral scale and corrosion product resulting high conductivity condensate at outlet condenser when we restarted up, beyond the acceptable limit. After assessing several options, chemical cleaning was the best way to overcome the problem according to condenser configuration. An 8 hour circulation of 5%wt citric acid had succeed reducing water conductivity from 50 μmhos/cm to below 5 μmhos/cm. The condensate water, then meets the required quality, i.e. pH 8.3 - 9.0; conductivity ≤ 5 μmhos/cm, therefore the power generator can be operated normally without any concern until now.

  17. Condensed matter physics

    CERN Document Server

    Marder, Michael P

    2010-01-01

    This Second Edition presents an updated review of the whole field of condensed matter physics. It consolidates new and classic topics from disparate sources, teaching not only about the effective masses of electrons in semiconductor crystals and band theory, but also about quasicrystals, dynamics of phase separation, why rubber is more floppy than steel, granular materials, quantum dots, Berry phases, the quantum Hall effect, and Luttinger liquids.

  18. Asymmetric condensed dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, Anthony; Diez-Tejedor, Alberto, E-mail: aguirre@scipp.ucsc.edu, E-mail: alberto.diez@fisica.ugto.mx [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA, 95064 (United States)

    2016-04-01

    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate must be lighter than a few tens of eV so that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of decoupling to the scale of the QCD phase transition or above. This requires large dark matter-to-photon ratios and very weak interactions with standard model particles.

  19. Distributed Max-SINR Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Heusdens, Richard

    2017-01-01

    In recent years, signal processing with ad hoc microphone arrays has attracted a lot of attention. Speech enhancement in noisy, interfered, and reverberant environments is one of the problems targeted by ad hoc microphone arrays. Most of the proposed solutions require knowledge of fingerprints......-SINR) criterion is used with the primal-dual method of multipliers for distributed filtering. The paper investigates the convergence of the algorithm in both synchronous and asynchronous schemes, and also discusses some practical pros and cons. The applicability of the proposed method is demonstrated by means...

  20. DFT-Domain Based Single-Microphone Noise Reduction for Speech Enhancement

    DEFF Research Database (Denmark)

    C. Hendriks, Richard; Gerkmann, Timo; Jensen, Jesper

    As speech processing devices like mobile phones, voice controlled devices, and hearing aids have increased in popularity, people expect them to work anywhere and at any time without user intervention. However, the presence of acoustical disturbances limits the use of these applications, degrades...... their performance, or causes the user difficulties in understanding the conversation or appreciating the device. A common way to reduce the effects of such disturbances is through the use of single-microphone noise reduction algorithms for speech enhancement. The field of single-microphone noise reduction...

  1. Soft Condensed Matter

    International Nuclear Information System (INIS)

    Jones, Richard A L

    2002-01-01

    The author states in the preface of the book that the aim is '...to give a unified overview of the various aspects of the physics of soft condensed matter'. The book succeeds in fulfilling this aim in many respects. The style is fluent and concise and gives the necessary explanations to make its content understandable to people with some knowledge of the basic principles of physics. The content of the book is complete enough to give a panoramic view of the landscape of soft condensed matter. The first two chapters give, respectively, a short introduction and a presentation of forces, energies and timescales, giving a general overview and pointing out the particular importance of different aspects such as timescales, which are much more important in soft condensed matter than in traditional or 'hard' condensed matter. The next chapter, devoted to phase transition, recalls that the equilibrium between two phases is controlled by free energy considerations. Spinodal decomposition is presented as a counterpart of nucleation and growth. Again, characteristic length scales are considered and applied to a phase separation mixture of polymers in a common solvent. The following three chapters are devoted respectively to specific topics: colloidal dispersion, polymers and gelation. The stability and phase behaviour of colloids are related to the interaction between colloidal particles. Properties of colloidal crystals as well as colloidal dispersion are depicted in terms of stabilization of crystalline colloids. The flow properties of colloidal dispersion are presented in terms of free energy minimization and the structure of the dispersion. After a brief introduction to polymer chemistry and architecture, the coil-globule transition is discussed. Viscoelasticity of polymers is described and discussed by introducing the notion of entanglement. This leads to the introduction of the tube model and the theory of reptation. The sol-gel transition is presented phenomenologically

  2. Condensed Matter Nuclear Science

    Science.gov (United States)

    Biberian, Jean-Paul

    2006-02-01

    1. General. A tribute to gene Mallove - the "Genie" reactor / K. Wallace and R. Stringham. An update of LENR for ICCF-11 (short course, 10/31/04) / E. Storms. New physical effects in metal deuterides / P. L. Hagelstein ... [et al.]. Reproducibility, controllability, and optimization of LENR experiments / D. J. Nagel -- 2. Experiments. Electrochemistry. Evidence of electromagnetic radiation from Ni-H systems / S. Focardi ... [et al.]. Superwave reality / I. Dardik. Excess heat in electrolysis experiments at energetics technologies / I. Dardik ... [et al.]. "Excess heat" during electrolysis in platinum/K[symbol]CO[symbol]/nickel light water system / J. Tian ... [et al.]. Innovative procedure for the, in situ, measurement of the resistive thermal coefficient of H(D)/Pd during electrolysis; cross-comparison of new elements detected in the Th-Hg-Pd-D(H) electrolytic cells / F. Celani ... [et al.]. Emergence of a high-temperature superconductivity in hydrogen cycled Pd compounds as an evidence for superstoihiometric H/D sites / A. Lipson ... [et al.]. Plasma electrolysis. Calorimetry of energy-efficient glow discharge - apparatus design and calibration / T. B. Benson and T. O. Passell. Generation of heat and products during plasma electrolysis / T. Mizuno ... [et al.]. Glow discharge. Excess heat production in Pd/D during periodic pulse discharge current in various conditions / A. B. Karabut. Beam experiments. Accelerator experiments and theoretical models for the electron screening effect in metallic environments / A. Huke, K. Czerski, and P. Heide. Evidence for a target-material dependence of the neutron-proton branching ratio in d+d reactions for deuteron energies below 20keV / A. Huke ... [et al.]. Experiments on condensed matter nuclear events in Kobe University / T. Minari ... [et al.]. Electron screening constraints for the cold fusion / K. Czerski, P. Heide, and A. Huke. Cavitation. Low mass 1.6 MHz sonofusion reactor / R. Stringham. Particle detection. Research

  3. The condensed matter physics

    International Nuclear Information System (INIS)

    Sapoval, B.

    1988-01-01

    The 1988 progress report of the laboratory of the Condensed Matter Physics (Polytechnic School, France), is presented. The Laboratory activities are related to the physics of semiconductors and disordered phases. The electrical and optical properties of the semiconductors, mixed conductor, superionic conductors and ceramics, are studied. Moreover, the interfaces of those systems and the sol-gel inorganic polymerization phenomena, are investigated. The most important results obtained, concern the following investigations: the electrochemical field effect transistor, the cathodoluminescence, the low energy secondary electrons emission, the fluctuations of a two-dimensional diffused junction and the aerogels [fr

  4. Topology in Condensed Matter

    CERN Document Server

    Monastyrsky, M I

    2006-01-01

    This book reports new results in condensed matter physics for which topological methods and ideas are important. It considers, on the one hand, recently discovered systems such as carbon nanocrystals and, on the other hand, new topological methods used to describe more traditional systems such as the Fermi surfaces of normal metals, liquid crystals and quasicrystals. The authors of the book are renowned specialists in their fields and present the results of ongoing research, some of it obtained only very recently and not yet published in monograph form.

  5. Nonnegative signal factorization with learnt instrument models for sound source separation in close-microphone recordings

    Science.gov (United States)

    Carabias-Orti, Julio J.; Cobos, Máximo; Vera-Candeas, Pedro; Rodríguez-Serrano, Francisco J.

    2013-12-01

    Close-microphone techniques are extensively employed in many live music recordings, allowing for interference rejection and reducing the amount of reverberation in the resulting instrument tracks. However, despite the use of directional microphones, the recorded tracks are not completely free from source interference, a problem which is commonly known as microphone leakage. While source separation methods are potentially a solution to this problem, few approaches take into account the huge amount of prior information available in this scenario. In fact, besides the special properties of close-microphone tracks, the knowledge on the number and type of instruments making up the mixture can also be successfully exploited for improved separation performance. In this paper, a nonnegative matrix factorization (NMF) method making use of all the above information is proposed. To this end, a set of instrument models are learnt from a training database and incorporated into a multichannel extension of the NMF algorithm. Several options to initialize the algorithm are suggested, exploring their performance in multiple music tracks and comparing the results to other state-of-the-art approaches.

  6. Optimization of capacitive microphone and pressure sensor performance by capacitor-electrode shaping

    NARCIS (Netherlands)

    Voorthuyzen, J.A.; Voorthuyzen, J.A.; Sprenkels, A.J.; van der Donk, A.G.H.; van der Donk, A.G.H.; Scheeper, P.R.; Scheeper, P.R.; Bergveld, Piet

    1991-01-01

    In many designs of capacitive microphones or pressure sensors the electrode size is chosen to be equal to the diaphragm size. In this paper it will be discussed whether an electrode size or shape that differs from that of the diaphragm is attractive for obtaining a maximum value for the sensor

  7. Reconstruction of arbitrary sound fields with a rigid-sphere microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    2013-01-01

    Over the last few years, several studies have examined the potential of using rigid-sphere microphone arrays for reconstructing sound fields with near-field acoustic holography (NAH). The existing methods provide a reconstruction of the sound field based on a spherical harmonic expansion. However...

  8. Efficient voice activity detection in reverberant enclosures using far field microphones

    DEFF Research Database (Denmark)

    Petsatodis, Theodore; Boukis, Christos

    2009-01-01

    An algorithm suitable for voice activity detection under reverberant conditions is proposed in this paper. Due to the use of far-filed microphones the proposed solution processes speech signals of highly-varying intensity and signal to noise ratio, that are contaminated with several echoes...

  9. Field trials using a digital hearing aid with active noise reduction and dual-microphone directionality

    NARCIS (Netherlands)

    Boymans, M.; Dreschler, W. A.

    2000-01-01

    In this study, we measured the effects of a digital hearing aid on speech recognition or reception in noise for two noise reduction concepts: active noise reduction by speech-sensitive processing (SSP) and improved directionality by a dual- or so-called twin-microphone system (TMS). This was

  10. Prediction of Quadcopter State through Multi-Microphone Side-Channel Fusion

    NARCIS (Netherlands)

    Koops, Hendrik Vincent; Garg, Kashish; Kim, Munsung; Li, Jonathan; Volk, Anja; Franchetti, Franz

    Improving trust in the state of Cyber-Physical Systems becomes increasingly important as more tasks become autonomous. We present a multi-microphone machine learning fusion approach to accurately predict complex states of a quadcopter drone in flight from the sound it makes using audio content

  11. Motorcycle detection and counting using stereo camera, IR camera, and microphone array

    Science.gov (United States)

    Ling, Bo; Gibson, David R. P.; Middleton, Dan

    2013-03-01

    Detection, classification, and characterization are the key to enhancing motorcycle safety, motorcycle operations and motorcycle travel estimation. Average motorcycle fatalities per Vehicle Mile Traveled (VMT) are currently estimated at 30 times those of auto fatalities. Although it has been an active research area for many years, motorcycle detection still remains a challenging task. Working with FHWA, we have developed a hybrid motorcycle detection and counting system using a suite of sensors including stereo camera, thermal IR camera and unidirectional microphone array. The IR thermal camera can capture the unique thermal signatures associated with the motorcycle's exhaust pipes that often show bright elongated blobs in IR images. The stereo camera in the system is used to detect the motorcyclist who can be easily windowed out in the stereo disparity map. If the motorcyclist is detected through his or her 3D body recognition, motorcycle is detected. Microphones are used to detect motorcycles that often produce low frequency acoustic signals. All three microphones in the microphone array are placed in strategic locations on the sensor platform to minimize the interferences of background noises from sources such as rain and wind. Field test results show that this hybrid motorcycle detection and counting system has an excellent performance.

  12. Temperature compensated, humidity insensitive, high-Tg TOPAS FBGs for accelerometers and microphones

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, W.; Markos, C.

    2012-01-01

    In this paper we present our latest work on Fiber Bragg Gratings (FBGs) in microstructured polymer optical fibers (mPOFs) and their application as strain sensing transducers in devices, such as accelerometers and microphones. We demonstrate how the cross-sensitivity of the FBG to temperature is e...... applications requiring high sensitivity due to the low Young's Modulus of polymer....

  13. Diagnostic accuracy of nasal cannula versus microphone for detection of snoring.

    Science.gov (United States)

    Pérez-Warnisher, María Teresa; Gómez-García, Teresa; Giraldo-Cadavid, Luis Fernando; Troncoso Acevedo, Maria Fernanda; Rodríguez Rodríguez, Paula; Carballosa de Miguel, Pilar; González Mangado, Nicolás

    2017-12-01

    Snoring is a common reason for referral to a sleep unit. Although there are several instruments to measure snoring, there is no gold standard for this purpose. In this study, we determine the diagnostic accuracy of the cannula as compared with the microphone, which are the two most commonly used tools. We performed a cross-sectional study of 75 patients who underwent baseline home sleep apnea testing for any reason. Snore intensity and percentage were assessed during Home sleep-apnea testing via nasal cannula and microphone in all patients. We performed a complete diagnostic accuracy analysis, assuming the microphone to be the reference instrument use in order to compare it with the cannula. The intra-class correlation coefficient between the cannula and microphone for the percentage of snoring was 0.25. The Bland Bland-Altman analysis to determine the agreement regarding the percentage of snoring showed a lower limit of -57.73 and an upper limit of 20.30. A linear regression analysis of the differences produced a negative slope of -0.86. The receiver operating characteristic curve for severe snoring using the cannula produced an area under the curve of 0.67 (P = 0.019). The cannula showed a sensitivity of 57.89 and a specificity of 73.21. The nasal cannula showed poor reliability and accuracy for measuring snoring. 2b. Laryngoscope, 127:2886-2890, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

  14. Environmental coefficients of the free-field sensitivity of measurement microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Cutanda Henriquez, Vicente; Torras-Rosell, Antoni

    2017-01-01

    The sensitivity of measurement microphones, both pressure and free field, is affected by changes in the environmental conditions, mainly temperature and static pressure. Static pressure and temperature coefficients for the pressure sensitivity have been the object of previous studies focused on L...

  15. MP.EXE, a Calculation Program for Pressure Reciprocity Calibration of Microphones

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1998-01-01

    A computer program is described which calculates the pressure sensitivity of microphones based on measurements of the electrical transfer impedance in a reciprocity calibration set-up. The calculations are performed according to the International Standard IEC 6194-2. In addition a number of optio...

  16. High frequency microphone measurements for transition detection on airfoils. NACA-0015 appendix report

    DEFF Research Database (Denmark)

    Døssing, Mads

    Time series of pressure fluctuations has been obtained using high frequency microphones distributed over the surface of airfoils undergoing wind tunnel tests in the LM Windtunnel, owned by ’LM Glasfiber’, Denmark. The present report describes the dataanalysis, with special attention given to tran...

  17. Near field acoustic holography with microphones mounted on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Moreno, Guillermo; Fernandez Grande, Efren

    2008-01-01

    Spherical near field acoustic holography (spherical NAH) is a technique that makes it pos-sible to reconstruct the sound field inside and just outside an acoustically transparent spherical surface on which the sound pressure is measured with an array of microphones with negligible scattering...

  18. Spherical near field acoustic holography with microphones on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Hald, Jørgen; Fernandez Grande, Efren

    2008-01-01

    Spherical near field acoustic holography (SNAH) is a recently developed technique that makes it possible to reconstruct the sound field inside and just outside an acoustically transparent spherical surface on which the sound pressure is measured with an array of microphones with negligible...

  19. Ice condenser experimental plan

    International Nuclear Information System (INIS)

    Kannberg, L.D.; Piepel, G.F.; Owczarski, P.C.; Liebetrau, A.M.

    1986-01-01

    An experimental plan is being developed to validate the computer code ICEDF. The code was developed to estimate the extent of aerosol retention in the ice compartments of pressurized water reactor ice condenser containment systems during severe accidents. The development of the experimental plan began with review of available information on the conditions under which the code will be applied. Computer-generated estimates of thermohydraulic and aerosol conditions entering the ice condenser were evaluated and along with other information, used to generate design criteria. The design criteria have been used for preliminary test assembly design and for generation of statistical test designs. Consideration of the phenomena to be evaluated in the testing program, as well as equipment and measurement limitations, have led to changes in the design criteria and to subsequent changes in the test assembly design and statistical test design. The overall strategy in developing the experimental plan includes iterative generation and evaluation of candidate test designs using computer codes for statistical test design and ICEDF for estimation of experimental results. Estimates of experimental variability made prior to actual testing will be verified by replicate testing at preselected design points

  20. Ferminoic physics in dipolariton condensates.

    Science.gov (United States)

    Su, Jung-Jung; Kim, Na Young; Yamamoto, Yoshihisa; Macdonald, Allan H

    2014-03-21

    An exciton polariton is an extremely light bosonic quasiparticle that is composed of an exciton and a photon. We report on a theoretical study of exciton-polariton condensation in a system with tunnel-coupled quantum wells. Because their excitons can carry an electric dipole moment, these systems have been referred to as dipolariton condensates. We use a fermionic mean-field theory that can address quantum well and other internal exciton degrees of freedom to describe the new physics present in dipolariton condensates. We find that the role of underlying fermonic degrees of freedom is enhanced and predict that metallic condensates can occur at high carrier densities.

  1. Development of closed-loop interface circuits for capacitive transducers with application to a MEMS capacitive microphone

    Science.gov (United States)

    Kadirvel, Karthik

    There has been a trend towards miniaturization and batch fabrication of sensors inspired by a similar trend in the electronics industry using novel fabrication techniques used in micro electromechanical system (MEMS) fabrication. Capacitive microphones, whose common applications include aeroacoustic measurement and cell phones, is one such sensor whose dimensions are being aggressively scaled down. In measurement microphones, miniaturization will facilitate improved measurement precision, and in cell phones, miniaturization will reduce printer circuit board space and complexity. Both applications will benefit from the potential cost reduction brought by the batch fabrication of sensors. As sensor geometry is scaled down, improved circuit techniques are required to measure the sensor output. This is because at small geometries sensor capacitance is comparable to unwanted parasitic capacitance which reduces the transducer sensitivity. Also, at reduced sensor geometry, the voltage required to bias the microphone could cause the microphone plates to pull in. The goal of this work is to design and characterize interface circuits that are suitable for miniature capacitive transducers. To achieve this goal, the performance of existing open and closed-loop interface circuits are investigated. Scaling of the performance metrics of the microphone and interface circuit as sensor geometry decreases is also investigated. A proof of concept closed-loop analog controller for a MEMS capacitive microphone is designed. A test apparatus is developed to characterize the system over the audio range by operating the microphone in a helium medium which increases the bandwidth of the test apparatus. Characterization of the microphone in open and closed loop mode of operation is presented. Results show that stable closed loop operation of the microphone is feasible with increased sensitivity and the potential to address pull-in issues.

  2. Microgravity condensing heat exchanger

    Science.gov (United States)

    Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor); North, Andrew (Inventor); Weislogel, Mark M. (Inventor)

    2011-01-01

    A heat exchanger having a plurality of heat exchanging aluminum fins with hydrophilic condensing surfaces which are stacked and clamped between two cold plates. The cold plates are aligned radially along a plane extending through the axis of a cylindrical duct and hold the stacked and clamped portions of the heat exchanging fins along the axis of the cylindrical duct. The fins extend outwardly from the clamped portions along approximately radial planes. The spacing between fins is symmetric about the cold plates, and are somewhat more closely spaced as the angle they make with the cold plates approaches 90.degree.. Passageways extend through the fins between vertex spaces which provide capillary storage and communicate with passageways formed in the stacked and clamped portions of the fins, which communicate with water drains connected to a pump externally to the duct. Water with no entrained air is drawn from the capillary spaces.

  3. Bose-Einstein Condensation

    International Nuclear Information System (INIS)

    Jaksch, D

    2003-01-01

    The Gross-Pitaevskii equation, named after one of the authors of the book, and its large number of applications for describing the properties of Bose-Einstein condensation (BEC) in trapped weakly interacting atomic gases, is the main topic of this book. In total the monograph comprises 18 chapters and is divided into two parts. Part I introduces the notion of BEC and superfluidity in general terms. The most important properties of the ideal and the weakly interacting Bose gas are described and the effects of nonuniformity due to an external potential at zero temperature are studied. The first part is then concluded with a summary of the properties of superfluid He. In Part II the authors describe the theoretical aspects of BEC in harmonically trapped weakly interacting atomic gases. A short and rather rudimentary chapter on collisions and trapping of atomic gases which seems to be included for completeness only is followed by a detailed analysis of the ground state, collective excitations, thermodynamics, and vortices as well as mixtures of BECs and the Josephson effect in BEC. Finally, the last three chapters deal with topics of more recent interest like BEC in optical lattices, low dimensional systems, and cold Fermi gases. The book is well written and in fact it provides numerous useful and important relations between the different properties of a BEC and covers most of the aspects of ultracold weakly interacting atomic gases from the point of view of condensed matter physics. The book contains a comprehensive introduction to BEC for physicists new to the field as well as a lot of detail and insight for those already familiar with this area. I therefore recommend it to everyone who is interested in BEC. Very clearly however, the intention of the book is not to provide prospects for applications of BEC in atomic physics, quantum optics or quantum state engineering and therefore the more practically oriented reader might sometimes wonder why exactly an equation is

  4. Supersymmetry is afraid of condensates

    Directory of Open Access Journals (Sweden)

    G. Domokos

    1983-01-01

    Full Text Available Supersymmetry is never broken by pair condensates of chiral superfields: the supersymmetry breaking part of Green's functions satisfies an equation which always has an identically vanishing solution. Hence any phase containing pair condensates is unstable due to its positive vacuum energy.

  5. A numerical study of the random-incidence and diffuse-field sensitivity of laboratory standard microphones using BEM

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Henriquez, Vicente Cutanda; Jacobsen, Finn

    2006-01-01

    to the definition of the latter, a number of plane waves coming from random directions and having random phases impinge simultaneously upon the microphone. The random-incidence sensitivity can be estimated using measurements made in an anechoic chamber, while the diffuse-field sensitivity requires a reverberation......The difference between the random-incidence sensitivity of a microphone and the diffusefield sensitivity is that according to the definition of the former, plane waves coming from different angles of incidence impinge successively onto the microphone under free-field conditions, whereas according...... Element Method has been used to study different aspects of the two realizations, such as the influence of the number of plane waves impinging on the microphone, the required amount of spatial averaging, etc....

  6. In-situ tuning threshold voltage of field-effect transistors based on blends of poly(3-hexylthiophene) with an insulator electret

    Science.gov (United States)

    Lu, Guanghao; Koch, Norbert; Neher, Dieter

    2015-08-01

    Blending the conjugated polymer poly(3-hexylthiophene) (P3HT) with the insulating electret polystyrene (PS), we show that the threshold voltage Vt of organic field-effect transistors (OFETs) can be easily and reversely tuned by applying a gate bias stress at 130 °C. It is proposed that this phenomenon is caused by thermally activated charge injection from P3HT into PS matrix, and that this charge is immobilized within the PS matrix after cooling down to room temperature. Therefore, room-temperature hysteresis-free FETs with desired Vt can be easily achieved. The approach is applied to reversely tune the OFET mode of operation from accumulation to depletion, and to build inverters.

  7. High performance organic nonvolatile memory transistors based on HfO2 and poly(α-methylstyrene) electret hybrid charge-trapping layers

    Science.gov (United States)

    Xu, W. C.; He, H. X.; Jing, X. S.; Wu, S. J.; Zhang, Z.; Gao, J. W.; Gao, X. S.; Zhou, G. F.; Lu, X. B.; Liu, J.-M.

    2017-08-01

    In this work, we fabricated a high performance flash-type organic nonvolatile memory transistor, which adopted polymer-electret poly(α-methylstyrene) (PαMS) and HfO2 films as hybrid charge trapping layer (CTL). Compared with a single HfO2 or PαMS CTL structure, the hybrid HfO2/PαMS CTL structure can provide enhanced charge trapping efficiency to increase the device operation speed and reduce the leakage current to boost the device reliability. The fabricated nonvolatile organic memory transistors with the hybrid CTL shows excellent electrical properties, including low operation voltage (8 V), high speed (erase cycles). The present work provides useful idea for the design of future low-power consumption and highly reliable organic nonvolatile memories.

  8. Free-field reciprocity calibration of laboratory standard (LS) microphones using a time selective technique

    DEFF Research Database (Denmark)

    Rasmussen, Knud; Barrera Figueroa, Salvador

    2006-01-01

    Although the basic principle of reciprocity calibration of microphones in a free field is simple, the practical problems are complicated due to the low signal-to-noise ratio and the influence of cross talk and reflections from the surroundings. The influence of uncorrelated noise can be reduced...... by conventional narrow-band filtering and time averaging, while correlated signals like cross talk and reflections can be eliminated by using time-selective postprocessing techniques. The technique used at DPLA overcomes both these problems using a B&K Pulse analyzer in the SSR mode (steady state response......) and an FFT-based time-selective technique. The complex electrical transfer impedance is measured in linear frequency steps from a few kHz to about three times the resonance frequency of the microphones. The missing values at low frequencies are estimated from a detailed knowledge of the pressure...

  9. Reconstruction of the signal produced by a directional sound source from remote multi-microphone recordings.

    Science.gov (United States)

    Guarato, Francesco; Hallam, John; Matsuo, Ikuo

    2011-09-01

    A mathematical method for reconstructing the signal produced by a directional sound source from knowledge of the same signal in the far field, i.e., microphone recordings, is developed. The key idea is to compute inverse filters that compensate for the directional filtering of the signal by the sound source directivity, using a least-square error optimization strategy. Previous work pointed out how the method strongly depends on arrival times of signal in the microphone recordings. Two strategies are used in this paper for calculating the time shifts that are afterward taken as inputs, together with source directivity, for the reconstruction. The method has been tested in a laboratory environment, where ground truth was available, with a Polaroid transducer as source. The reconstructions are similar with both strategies. The performance of the method also depends on source orientation. © 2011 Acoustical Society of America

  10. Design of Small MEMS Microphone Array Systems for Direction Finding of Outdoors Moving Vehicles

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    2014-03-01

    Full Text Available In this paper, a MEMS microphone array system scheme is proposed which implements real-time direction of arrival (DOA estimation for moving vehicles. Wind noise is the primary source of unwanted noise on microphones outdoors. A multiple signal classification (MUSIC algorithm is used in this paper for direction finding associated with spatial coherence to discriminate between the wind noise and the acoustic signals of a vehicle. The method is implemented in a SHARC DSP processor and the real-time estimated DOA is uploaded through Bluetooth or a UART module. Experimental results in different places show the validity of the system and the deviation is no bigger than 6° in the presence of wind noise.

  11. Characteristics and measurement of supersonic projectile shock waves by a 32-microphone ring array

    Science.gov (United States)

    Chang, Ho; Wu, Yan-Chyuan; Tsung, Tsing-Tshih

    2011-08-01

    This paper discusses about the characteristics of supersonic projectile shock wave in muzzle region during firing of high explosive anti-tank (HEAT) and high explosive (HE) projectiles. HEAT projectiles are fired horizontally at a muzzle velocity of Mach 3.5 from a medium caliber tank gun equipped with a newly designed multi-perforated muzzle brake, whereas HE projectiles are fired at elevation angles at a muzzle velocity of Mach 2 from a large caliber howitzer equipped with a newly designed double-baffle muzzle brake. In the near field, pressure signatures of the N-wave generated from projectiles are measured by 32-microphone ring array wrapped by cotton sheath. Records measured by the microphone array are used to demonstrate several key characteristics of the shock wave of supersonic projectile. All measurements made in this study can be a significant reference for developing guns, tanks, or the chassis of fighting vehicles.

  12. Assessment of Operational Progress of NASA Langley Developed Windshield and Microphone for Infrasound

    Science.gov (United States)

    2013-04-01

    and Seismic Sensing, Magnetic and Electric Sensors, 2008. 7. Help Documentation, MATLAB ® R2011b, MathWorks (2011). No. of Copies Organization...using the MATLAB ,* Signal Processing Toolbox function “tfestimate” (7). This function returns a complex transfer function, from which the magnitude...between the two microphones at the same separations. * MATLAB is a registered trademark of The MathWorks

  13. Microphone Handling Noise: Measurements of Perceptual Threshold and Effects on Audio Quality.

    Science.gov (United States)

    Kendrick, Paul; Jackson, Iain R; Fazenda, Bruno M; Cox, Trevor J; Li, Francis F

    2015-01-01

    A psychoacoustic experiment was carried out to test the effects of microphone handling noise on perceived audio quality. Handling noise is a problem affecting both amateurs using their smartphones and cameras, as well as professionals using separate microphones and digital recorders. The noises used for the tests were measured from a variety of devices, including smartphones, laptops and handheld microphones. The signal features that characterise these noises are analysed and presented. The sounds include various types of transient, impact noises created by tapping or knocking devices, as well as more sustained sounds caused by rubbing. During the perceptual tests, listeners auditioned speech podcasts and were asked to rate the degradation of any unwanted sounds they heard. A representative design test methodology was developed that tried to encourage everyday rather than analytical listening. Signal-to-noise ratio (SNR) of the handling noise events was shown to be the best predictor of quality degradation. Other factors such as noise type or background noise in the listening environment did not significantly affect quality ratings. Podcast, microphone type and reproduction equipment were found to be significant but only to a small extent. A model allowing the prediction of degradation from the SNR is presented. The SNR threshold at which 50% of subjects noticed handling noise was found to be 4.2 ± 0.6 dBA. The results from this work are important for the understanding of our perception of impact sound and resonant noises in recordings, and will inform the future development of an automated predictor of quality for handling noise.

  14. Microphone Handling Noise: Measurements of Perceptual Threshold and Effects on Audio Quality.

    Directory of Open Access Journals (Sweden)

    Paul Kendrick

    Full Text Available A psychoacoustic experiment was carried out to test the effects of microphone handling noise on perceived audio quality. Handling noise is a problem affecting both amateurs using their smartphones and cameras, as well as professionals using separate microphones and digital recorders. The noises used for the tests were measured from a variety of devices, including smartphones, laptops and handheld microphones. The signal features that characterise these noises are analysed and presented. The sounds include various types of transient, impact noises created by tapping or knocking devices, as well as more sustained sounds caused by rubbing. During the perceptual tests, listeners auditioned speech podcasts and were asked to rate the degradation of any unwanted sounds they heard. A representative design test methodology was developed that tried to encourage everyday rather than analytical listening. Signal-to-noise ratio (SNR of the handling noise events was shown to be the best predictor of quality degradation. Other factors such as noise type or background noise in the listening environment did not significantly affect quality ratings. Podcast, microphone type and reproduction equipment were found to be significant but only to a small extent. A model allowing the prediction of degradation from the SNR is presented. The SNR threshold at which 50% of subjects noticed handling noise was found to be 4.2 ± 0.6 dBA. The results from this work are important for the understanding of our perception of impact sound and resonant noises in recordings, and will inform the future development of an automated predictor of quality for handling noise.

  15. Determining Sound Source Orientation from Analytical Source Directivity and Real Multi-Microphone Recordings

    DEFF Research Database (Denmark)

    Guarato, Francesco; Hallam, John; Vanderelst, Dieter

    2009-01-01

    been performed in an ordinary environment by using a Polaroid transducer as the sound source emitting a broadband signal in the ultrasonic range. Such an acoustic signal has similar structure to those used by bats to echolocate. Results show that method is precise provided that the source directivity...... ensonifies the microphone array sufficiently. Further developments of the method, and its ultimate application to the reconstruction of emitted bat calls from remote recordings, are discussed....

  16. Determining Sound Source Orientation from Source Directivity and Multi-microphone Recordings

    DEFF Research Database (Denmark)

    Guarato, Francesco; Hallam, John

    been performed in an ordinary environment by using a Polaroid transducer as the sound source emitting a broadband signal in the ultrasonic range. Such an acoustic signal has similar structure to those used by bats to echolocate. Results show that method is precise provided that the source directivity...... ensonifies the microphone array sufficiently. Further developments of the method, and its ultimate application to the reconstruction of emitted bat calls from remote recordings, are discussed....

  17. Mechanical performance of SiC based MEMS capacitive microphone for ultrasonic detection in harsh environment

    Science.gov (United States)

    Zawawi, S. A.; Hamzah, A. A.; Mohd-Yasin, F.; Majlis, B. Y.

    2017-08-01

    In this project, SiC based MEMS capacitive microphone was developed for detecting leaked gas in extremely harsh environment such as coal mines and petroleum processing plants via ultrasonic detection. The MEMS capacitive microphone consists of two parallel plates; top plate (movable diaphragm) and bottom (fixed) plate, which separated by an air gap. While, the vent holes were fabricated on the back plate to release trapped air and reduce damping. In order to withstand high temperature and pressure, a 1.0 μm thick SiC diaphragm was utilized as the top membrane. The developed SiC could withstand a temperature up to 1400°C. Moreover, the 3 μm air gap is invented between the top membrane and the bottom plate via wafer bonding. COMSOL Multiphysics simulation software was used for design optimization. Various diaphragms with sizes of 600 μm2, 700 μm2, 800 μm2, 900 μm2 and 1000 μm2 are loaded with external pressure. From this analysis, it was observed that SiC microphone with diaphragm width of 1000 μm2 produced optimal surface vibrations, with first-mode resonant frequency of approximately 36 kHz. The maximum deflection value at resonant frequency is less than the air gap thickness of 8 mu;m, thus eliminating the possibility of shortage between plates during operation. As summary, the designed SiC capacitive microphone has high potential and it is suitable to be applied in ultrasonic gas leaking detection in harsh environment.

  18. Ad Hoc Microphone Array Beamforming Using the Primal-Dual Method of Multipliers

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Heusdens, Richard

    2016-01-01

    In the recent years, there have been increasing amount of researches aiming at optimal beamforming with ad hoc microphone arrays, mostly with fusion-based schemes. However, huge amount of computational complexity and communication overhead impede many of these algorithms from being useful in prac...... the distributed linearly-constrained minimum variance beamformer using the the state of the art primal-dual method of multipliers. We study the proposed algorithm with an experiment....

  19. Microphonics detuning compensation in 3.9 GHZ superconducting RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ruben Carcagno et al.

    2003-10-20

    Mechanical vibrations can detune superconducting radio frequency (SCRF) cavities unless a tuning mechanism counteracting the vibrations is present. Due to their narrow operating bandwidth and demanding mechanical structure, the 13-cell 3.9GHz SCRF cavities for the Charged Kaons at Main Injector (CKM) experiment at Fermilab are especially susceptible to this microphonic phenomena. We present early results correlating RF frequency detuning with cavity vibration measurements for CKM cavities; initial detuning compensation results with piezoelectric actuators are also presented.

  20. Characterization of a tooth microphone coupled to an oral appliance device: A new system for monitoring OSA patients.

    Science.gov (United States)

    Castillo, Yolanda; Blanco-Almazan, Dolores; Whitney, James; Mersky, Barry; Jane, Raimon

    2017-07-01

    Obstructive sleep apnea (OSA) is a highly prevalent chronic disease, especially in elderly and obese populations. Despite constituting a serious health, social and economic problem, most patients remain undiagnosed and untreated due to limitations in current equipment. In this work, we propose a novel method to diagnose OSA and monitor therapy adherence and effectiveness at home in a non-invasive and inexpensive way: combining acoustic analysis of breathing and snoring sounds with oral appliance therapy (OA). Audiodontics has introduced a new sensor, a tooth microphone coupled to an OA device, which is the main pillar of this system. The objective of this work is to characterize the response of this sensor, comparing it with a commercial tracheal microphone (Biopac transducer). Signals containing OSA-related sounds were acquired simultaneously with the two microphones for that purpose. They were processed and analyzed in time, frequency and time-frequency domains, in a custom MATLAB interface. We carried out a single-event approach focused on breaths, snores and apnea episodes. We found that the quality of the signals obtained by both microphones was quite similar, although the tooth microphone spectrum concentrated more energy at the high-frequency band. This opens a new field of study about high-frequency components of snores and breathing sounds. These characteristics, together with its intraoral position, wireless option and combination with customizable OAs, give the tooth microphone a great potential to reduce the impact of sleep disorders, by enabling prompt detection and continuous monitoring of patients at home.

  1. Optimization of Fixed Microphone Array in High Speed Train Noises Identification Based on Far-Field Acoustic Holography

    Directory of Open Access Journals (Sweden)

    Rujia Wang

    2017-01-01

    Full Text Available Acoustical holography has been widely applied for noise sources location and sound field measurement. Performance of the microphones array directly determines the sound source recognition method. Therefore, research is very important to the performance of the microphone array, its array of applications, selection, and how to design instructive. In this paper, based on acoustic holography moving sound source identification theory, the optimization method is applied in design of the microphone array, we select the main side lobe ratio and the main lobe area as the optimization objective function and then put the optimization method use in the sound source identification based on holography, and finally we designed this paper to optimize microphone array and compare the original array of equally spaced array with optimization results; by analyzing the optimization results and objectives, we get that the array can be achieved which is optimized not only to reduce the microphone but also to change objective function results, while improving the far-field acoustic holography resolving effect. Validation experiments have showed that the optimization method is suitable for high speed trains sound source identification microphone array optimization.

  2. Multiresolution Source/Filter Model for Low Bitrate Coding of Spot Microphone Signals

    Directory of Open Access Journals (Sweden)

    Panagiotis Tsakalides

    2008-04-01

    Full Text Available A multiresolution source/filter model for coding of audio source signals (spot recordings is proposed. Spot recordings are a subset of the multimicrophone recordings of a music performance, before the mixing process is applied for producing the final multichannel audio mix. The technique enables low bitrate coding of spot signals with good audio quality (above 3.0 perceptual grade compared to the original. It is demonstrated that this particular model separates the various microphone recordings of a multimicrophone recording into a part that mainly characterizes a specific microphone signal and a part that is common to all signals of the same recording (and can thus be omitted during transmission. Our interest in low bitrate coding of spot recordings is related to applications such as remote mixing and real-time collaboration of musicians who are geographically distributed. Using the proposed approach, it is shown that it is possible to encode a multimicrophone audio recording using a single audio channel only, with additional information for each spot microphone signal in the order of 5 kbps, for good-quality resynthesis. This is verified by employing both objective and subjective measures of performance.

  3. Multiresolution Source/Filter Model for Low Bitrate Coding of Spot Microphone Signals

    Directory of Open Access Journals (Sweden)

    Mouchtaris Athanasios

    2008-01-01

    Full Text Available A multiresolution source/filter model for coding of audio source signals (spot recordings is proposed. Spot recordings are a subset of the multimicrophone recordings of a music performance, before the mixing process is applied for producing the final multichannel audio mix. The technique enables low bitrate coding of spot signals with good audio quality (above 3.0 perceptual grade compared to the original. It is demonstrated that this particular model separates the various microphone recordings of a multimicrophone recording into a part that mainly characterizes a specific microphone signal and a part that is common to all signals of the same recording (and can thus be omitted during transmission. Our interest in low bitrate coding of spot recordings is related to applications such as remote mixing and real-time collaboration of musicians who are geographically distributed. Using the proposed approach, it is shown that it is possible to encode a multimicrophone audio recording using a single audio channel only, with additional information for each spot microphone signal in the order of 5 kbps, for good-quality resynthesis. This is verified by employing both objective and subjective measures of performance.

  4. Mitigating Wind Induced Noise in Outdoor Microphone Signals Using a Singular Spectral Subspace Method

    Directory of Open Access Journals (Sweden)

    Omar Eldwaik

    2018-01-01

    Full Text Available Wind induced noise is one of the major concerns of outdoor acoustic signal acquisition. It affects many field measurement and audio recording scenarios. Filtering such noise is known to be difficult due to its broadband and time varying nature. In this paper, a new method to mitigate wind induced noise in microphone signals is developed. Instead of applying filtering techniques, wind induced noise is statistically separated from wanted signals in a singular spectral subspace. The paper is presented in the context of handling microphone signals acquired outdoor for acoustic sensing and environmental noise monitoring or soundscapes sampling. The method includes two complementary stages, namely decomposition and reconstruction. The first stage decomposes mixed signals in eigen-subspaces, selects and groups the principal components according to their contributions to wind noise and wanted signals in the singular spectrum domain. The second stage reconstructs the signals in the time domain, resulting in the separation of wind noise and wanted signals. Results show that microphone wind noise is separable in the singular spectrum domain evidenced by the weighted correlation. The new method might be generalized to other outdoor sound acquisition applications.

  5. Finite element computation of elliptical vocal tract impedances using the two-microphone transfer function method.

    Science.gov (United States)

    Arnela, Marc; Guasch, Oriol

    2013-06-01

    A two-microphone transfer function (TMTF) method is adapted to a numerical framework to compute the radiation and input impedances of three-dimensional vocal tracts of elliptical cross-section. In its simplest version, the TMTF method only requires measuring the acoustic pressure at two points in an impedance duct and the postprocessing of the corresponding transfer function. However, some considerations are to be taken into account when using the TMTF method in the numerical context, which constitute the main objective of this paper. In particular, the importance of including absorption at the impedance duct walls to avoid lengthy numerical simulations is discussed and analytical complex axial wave numbers for elliptical ducts are derived for this purpose. It is also shown how the direct impedance of plane wave propagation can be computed beyond the TMTF maximum threshold frequency by appropriate location of the virtual microphones. Virtual microphone spacing is also discussed on the basis of the so-called singularity factor. Numerical examples include the computation of the radiation impedance of vowels /a/, /i/, and /u/ and the input impedance of vowel /a/, for simplified vocal tracts of circular and elliptical cross-sections.

  6. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  7. A method for improving the drop test performance of a MEMS microphone

    Science.gov (United States)

    Winter, Matthias; Ben Aoun, Seifeddine; Feiertag, Gregor; Leidl, Anton; Scheele, Patrick; Seidel, Helmut

    2009-05-01

    Most micro electro mechanical system (MEMS) microphones are designed as capacitive microphones where a thin conductive membrane is located in front of a rigid counter electrode. The membrane is exposed to the environment to convert sound into vibrations of the membrane. The movement of the membrane causes a change in the capacitance between the membrane and the counter electrode. The resonance frequency of the membrane is designed to occur above the acoustic spectrum to achieve a linear frequency response. To obtain a good sensitivity the thickness of the membrane must be as small as possible, typically below 0.5 μm. These fragile membranes may be damaged by rapid pressure changes. For cell phones, drop tests are among the most relevant reliability tests. The extremely high acceleration during the drop impact leads to fast pressure changes in the microphone which could result in a rupture of the membrane. To overcome this problem a stable protection layer can be placed at a small distance to the membrane. The protective layer has small holes to form a low pass filter for air pressure. The low pass filter reduces pressure changes at high frequencies so that damage to the membrane by excitation in resonance will be prevented.

  8. Comparison of Computational and Experimental Microphone Array Results for an 18%-Scale Aircraft Model

    Science.gov (United States)

    Lockard, David P.; Humphreys, William M.; Khorrami, Mehdi R.; Fares, Ehab; Casalino, Damiano; Ravetta, Patricio A.

    2015-01-01

    An 18%-scale, semi-span model is used as a platform for examining the efficacy of microphone array processing using synthetic data from numerical simulations. Two hybrid RANS/LES codes coupled with Ffowcs Williams-Hawkings solvers are used to calculate 97 microphone signals at the locations of an array employed in the NASA LaRC 14x22 tunnel. Conventional, DAMAS, and CLEAN-SC array processing is applied in an identical fashion to the experimental and computational results for three different configurations involving deploying and retracting the main landing gear and a part span flap. Despite the short time records of the numerical signals, the beamform maps are able to isolate the noise sources, and the appearance of the DAMAS synthetic array maps is generally better than those from the experimental data. The experimental CLEAN-SC maps are similar in quality to those from the simulations indicating that CLEAN-SC may have less sensitivity to background noise. The spectrum obtained from DAMAS processing of synthetic array data is nearly identical to the spectrum of the center microphone of the array, indicating that for this problem array processing of synthetic data does not improve spectral comparisons with experiment. However, the beamform maps do provide an additional means of comparison that can reveal differences that cannot be ascertained from spectra alone.

  9. Speech Recognition for Environmental Control: Effect of Microphone Type, Dysarthria, and Severity on Recognition Results.

    Science.gov (United States)

    Fager, Susan Koch; Burnfield, Judith M

    2015-01-01

    This study examines the use of commercially available automatic speech recognition (ASR) across microphone options as access to environmental control for individuals with and without dysarthria. A study of two groups of speakers (typical speech and dysarthria), was conducted to understand their performance using ASR and various microphones for environmental control. Specifically, dependent variables examined included attempts per command, recognition accuracy, frequency of error type, and perceived workload. A further sub-analysis of the group of participants with dysarthria examined the impact of severity. Results indicated a significantly larger number of attempts were required (P = 0.007), and significantly lower recognition accuracies were achieved by the dysarthric participants (P = 0.010). A sub-analysis examining severity demonstrated no significant differences between the typical speakers and participants with mild dysarthria. However, significant differences were evident (P = 0.007, P = 0.008) between mild and moderate-severe dysarthric participants. No significant differences existed across microphones. A higher frequency of threshold errors occurred for typical participants and no response errors for moderate-severe dysarthrics. There were no significant differences on the NASA Task Load Index.

  10. Virtual design and optimization studies for industrial silicon microphones applying tailored system-level modeling

    Science.gov (United States)

    Kuenzig, Thomas; Dehé, Alfons; Krumbein, Ulrich; Schrag, Gabriele

    2018-05-01

    Maxing out the technological limits in order to satisfy the customers’ demands and obtain the best performance of micro-devices and-systems is a challenge of today’s manufacturers. Dedicated system simulation is key to investigate the potential of device and system concepts in order to identify the best design w.r.t. the given requirements. We present a tailored, physics-based system-level modeling approach combining lumped with distributed models that provides detailed insight into the device and system operation at low computational expense. The resulting transparent, scalable (i.e. reusable) and modularly composed models explicitly contain the physical dependency on all relevant parameters, thus being well suited for dedicated investigation and optimization of MEMS devices and systems. This is demonstrated for an industrial capacitive silicon microphone. The performance of such microphones is determined by distributed effects like viscous damping and inhomogeneous capacitance variation across the membrane as well as by system-level phenomena like package-induced acoustic effects and the impact of the electronic circuitry for biasing and read-out. The here presented model covers all relevant figures of merit and, thus, enables to evaluate the optimization potential of silicon microphones towards high fidelity applications. This work was carried out at the Technical University of Munich, Chair for Physics of Electrotechnology. Thomas Kuenzig is now with Infineon Technologies AG, Neubiberg.

  11. Condenser retubing-criteria manual

    International Nuclear Information System (INIS)

    Impagliazzo, A.M.; Bell, R.J.; Curlett, P.L.; Gordon, H.L.

    1982-05-01

    The objective of this document is to provide engineering assistance to utilities involved in retubing steam surface condensers with corrosion-resistant materials, such as titanium, and the recently developed high alloy pit-resistant steels. Field tests and recent operating experience have shown titanium and at least one of the high alloy pit-resistant steels to be virtually immune to the usual forms of corrosion occurring in steam surface condensers. This, together with the trend toward elimination of copper alloys in the circulating water system, has caused many utilities to retube their condensers with these materials

  12. Bose condensation in (random traps

    Directory of Open Access Journals (Sweden)

    V.A. Zagrebnov

    2009-01-01

    Full Text Available We study a non-interacting (perfect Bose-gas in random external potentials (traps. It is shown that a generalized Bose-Einstein condensation in the random eigenstates manifests if and only if the same occurs in the one-particle kinetic-energy eigenstates, which corresponds to the generalized condensation of the free Bose-gas. Moreover, we prove that the amounts of both condensate densities are equal. This statement is relevant for justification of the Bogoliubov approximation} in the theory of disordered boson systems.

  13. Condensation coefficient of water in a weak condensation state

    International Nuclear Information System (INIS)

    Kobayashi, Kazumichi; Watanabe, Shunsuke; Yamano, Daigo; Yano, Takeru; Fujikawa, Shigeo

    2008-01-01

    The condensation coefficient of water at a vapor-liquid interface is determined by combining shock tube experiments and numerical simulations of the Gaussian-BGK Boltzmann equation. The time evolution in thickness of a liquid film, which is formed on the shock tube endwall behind the shock wave reflected at the endwall, is measured with an optical interferometer consisting of the physical beam and the reference one. The reference beam is utilized to eliminate systematic noises from the physical beam. The growth rate of the film is evaluated from the measured time evolution and it is incorporated into the kinetic boundary condition for the Boltzmann equation. From a numerical simulation using the boundary condition, the condensation coefficient of water is uniquely deduced. The results show that, in a condition of weak condensation near a vapor-liquid equilibrium state, the condensation coefficient of water is almost equal to the evaporation coefficient estimated by molecular dynamics simulations near a vapor-liquid equilibrium state and it decreases as the system becomes a nonequilibrium state. The condensation coefficient of water is nearly identical with that of methanol [Mikami, S., Kobayashi, K., Ota, T., Fujikawa, S., Yano, T., Ichijo, M., 2006. Molecular gas dynamics approaches to interfacial phenomena accompanied with condensation. Exp. Therm. Fluid Sci. 30, 795-800].

  14. Condensation coefficient of water in a weak condensation state

    Science.gov (United States)

    Kobayashi, Kazumichi; Watanabe, Shunsuke; Yamano, Daigo; Yano, Takeru; Fujikawa, Shigeo

    2008-07-01

    The condensation coefficient of water at a vapor-liquid interface is determined by combining shock tube experiments and numerical simulations of the Gaussian-BGK Boltzmann equation. The time evolution in thickness of a liquid film, which is formed on the shock tube endwall behind the shock wave reflected at the endwall, is measured with an optical interferometer consisting of the physical beam and the reference one. The reference beam is utilized to eliminate systematic noises from the physical beam. The growth rate of the film is evaluated from the measured time evolution and it is incorporated into the kinetic boundary condition for the Boltzmann equation. From a numerical simulation using the boundary condition, the condensation coefficient of water is uniquely deduced. The results show that, in a condition of weak condensation near a vapor-liquid equilibrium state, the condensation coefficient of water is almost equal to the evaporation coefficient estimated by molecular dynamics simulations near a vapor-liquid equilibrium state and it decreases as the system becomes a nonequilibrium state. The condensation coefficient of water is nearly identical with that of methanol [Mikami, S., Kobayashi, K., Ota, T., Fujikawa, S., Yano, T., Ichijo, M., 2006. Molecular gas dynamics approaches to interfacial phenomena accompanied with condensation. Exp. Therm. Fluid Sci. 30, 795-800].

  15. Efficient, Long-Life Biocidal Condenser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Environmental control systems for manned lunar and planetary bases will require condensing heat exchangers to control humidity in manned modules. Condensing surfaces...

  16. Condenser assembly system for an appliance

    Energy Technology Data Exchange (ETDEWEB)

    Litch, Andrew David

    2017-10-17

    An appliance includes a compact condenser assembly formed with at least two separately and independently produced wire on tube condensers. Each of the at least two wire on tube condensers has a condenser inlet and a condenser outlet. The at least two wire on tube condensers are at least substantially locked and positioned in a matingly engaged configuration forming a compact condenser assembly. The at least two wire on tube condensers are configured to be operationally connected in at least one of a parallel configuration, a series configuration, a selectable configuration, and a bypass configuration.

  17. Steam generators, turbines, and condensers. Volume six

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Volume six covers steam generators (How steam is generated, steam generation in a PWR, vertical U-tube steam generators, once-through steam generators, how much steam do steam generators make?), turbines (basic turbine principles, impulse turbines, reaction turbines, turbine stages, turbine arrangements, turbine steam flow, steam admission to turbines, turbine seals and supports, turbine oil system, generators), and condensers (need for condensers, basic condenser principles, condenser arrangements, heat transfer in condensers, air removal from condensers, circulating water system, heat loss to the circulating water system, factors affecting condenser performance, condenser auxiliaries)

  18. OPTIMAL EVAPORATING AND CONDENSING TEMPERATURES ...

    African Journals Online (AJOL)

    ORC) in a hot and humid environment. A theoretical procedure is proposed for the determination of the optimal evaporation temperature (OET) and optimal condensing temperature (OCT) of a subcritical ORC plant, which is based on ...

  19. Solar engineering - a condensed course

    Energy Technology Data Exchange (ETDEWEB)

    Broman, Lars

    2011-11-15

    The document represents the material covered in a condensed two-week course focusing on the most important thermal and PV solar energy engineering topics, while also providing some theoretical background.

  20. Condensed Matter Nuclear Science

    Science.gov (United States)

    Takahashi, Akito; Ota, Ken-Ichiro; Iwamura, Yashuhiro

    Preface -- 1. General. Progress in condensed matter nuclear science / A. Takahashi. Summary of ICCF-12 / X. Z. Li. Overview of light water/hydrogen-based low-energy nuclear reactions / G. H. Miley and P. J. Shrestha -- 2. Excess heat and He detection. Development of "DS-reactor" as the practical reactor of "cold fusion" based on the "DS-cell" with "DS-cathode" / Y. Arata and Y.-C. Zhang. Progress in excess of power experiments with electrochemical loading of deuterium in palladium / V. Violante ... [et al.]. Anomalous energy generation during conventional electrolysis / T. Mizuno and Y. Toriyabe. "Excess heat" induced by deuterium flux in palladium film / B. Liu ... [et al.]. Abnormal excess heat observed during Mizuno-type experiments / J.-F. Fauvarque, P. P. Clauzon and G. J.-M. Lallevé. Seebeck envelope calorimetry with a Pd|D[symbol]O + H[symbol]SO[symbol] electrolytic cell / W.-S. Zhang, J. Dash and Q. Wang. Observation and investigation of nuclear fusion and self-induced electric discharges in liquids / A. I. Koldamasov ... [et al.]. Description of a sensitive seebeck calorimeter used for cold fusion studies / E. Storms. Some recent results at ENEA / M. Apicella ... [et al.]. Heat measurement during plasma electrolysis / K. Iizumi ... [et al.]. Effect of an additive on thermal output during electrolysis of heavy water with a palladium cathode / Q. Wang and J. Dash. Thermal analysis of calorimetric systems / L. D'Aulerio ... [et al.]. Surface plasmons and low-energy nuclear reactions triggering / E. Castagna ... [et al.]. Production method for violent TCB jet plasma from cavity / F. Amini. New results and an ongoing excess heat controversy / L. Kowalski ... [et al.] -- 3. Transmutation. Observation of surface distribution of products by X-ray fluorescence spectrometry during D[symbol] gas permeation through Pd Complexes / Y. Iwamura ... [et al.]. Discharge experiment using Pd/CaO/Pd multi-layered cathode / S. Narita ... [et al.]. Producing transmutation

  1. Implementation of Hybrid Speech Dereverberation Systems and Proposing Dual Microphone Farsi Database in Order to Evaluating Enhancement Systems

    Directory of Open Access Journals (Sweden)

    Farhad Faghani

    2013-01-01

    Full Text Available In various applications, such as speech recognition and automatic teleconferencing, the recorded speech signals may be corrupted by both noise and reverberation. Reverberation causes a noticeable change in speech intelligibility and quality. In this research, firstly reverberation is described. There are some de-reverberation enhancement algorithms that use only one microphone. They mostly use inverse filtering and spectral subtraction as their sub-systems. On the other hand, there are many multi-microphone speech enhancement systems; Delay-and-sum beam former is the most famous amongst them. Moreover, several efficient approaches have been also reported that use linear prediction (LP residual signal, inverse filtering, and phase error. Despite the improvements and benefits gained by the use of several input microphones, considering the tradeoff between these gains and the complexity and computational cost forced by the use of more microphones, many researchers have focused on dual-microphones systems. So, a review on Microphone array signal processing is explained and then an arrangement for two microphones systems is proposed. As we want to evaluate these algorithms for Farsi speech signals, the problem of speech intelligibility assessment has been explained and a Farsi word list for Diagnostic Rhyme Test (DRT is presented.The structure of presented word list is similar to that of English DRT words. In this research, after a brief study of above-mentioned methods, we propose and implement some hybrid techniques to benefit from the advantages of several methods and achieve significant improvement in output signals. It will be shown that the proposed method performs superior to the state-of-the-art dereverberation algorithms.

  2. Condensation: the new deal; Condensation: la nouvelle donne

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-06-01

    The principle of condensation boilers is based on the recovery of the latent heat of the steam generated by the combustion of natural gas. This technology was introduced in France at the end of the 80's but failed in its promise because of the complexity of the equipments available at that time. Today, constructors' offer is more mature and reliable and the context has changed. This technology can conciliate three goals: a mastery of energy consumptions, the comfort of the user and the respect of environment. This meeting organized by the research center of Gaz de France (Cegibat), was a good opportunity to makes a status of the market of individual condensation systems in France and in Europe, to present the situation of this technology today and the 10 golden rules for the fitting and maintenance of individual condensation boilers, and to present some technical references, examples and results of today's offer. (J.S.)

  3. Research progress of control of condensate depression for condenser

    Science.gov (United States)

    Liu, Ying; Liang, Run; Li, Fengyu

    2017-08-01

    It is introduced that significance and structure of the condensate depression control system. In accordance with controller devised procedure, we analyze and elaborate how to construct the lumped parameter and dynamic mathematical model which possesses distinct physics significance. Neural network model being called black-box model is also introduced. We analyze and contrast the control technique of condensate depression as conventional PI control, fuzzy PI control and fuzzy control. It is indicated that if the controller of condensate depression were devised inappropriate, while the steam discharged of turbine varying by a large margin, would result in the rotation rate of cooling water circulating pump accelerating at a great lick even to trigger the galloping danger which is less impressive for the units operating safely.

  4. Introduction. Cosmology meets condensed matter.

    Science.gov (United States)

    Kibble, T W B; Pickett, G R

    2008-08-28

    At first sight, low-temperature condensed-matter physics and early Universe cosmology seem worlds apart. Yet, in the last few years a remarkable synergy has developed between the two. It has emerged that, in terms of their mathematical description, there are surprisingly close parallels between them. This interplay has been the subject of a very successful European Science Foundation (ESF) programme entitled COSLAB ('Cosmology in the Laboratory') that ran from 2001 to 2006, itself built on an earlier ESF network called TOPDEF ('Topological Defects: Non-equilibrium Field Theory in Particle Physics, Condensed Matter and Cosmology'). The articles presented in this issue of Philosophical Transactions A are based on talks given at the Royal Society Discussion Meeting 'Cosmology meets condensed matter', held on 28 and 29 January 2008. Many of the speakers had participated earlier in the COSLAB programme, but the strength of the field is illustrated by the presence also of quite a few new participants.

  5. Condensational theory of stationary tornadoes

    International Nuclear Information System (INIS)

    Makarieva, A.M.; Gorshkov, V.G.; Nefiodov, A.V.

    2011-01-01

    Using the Bernoulli integral for air streamline with condensing water vapor a stationary axisymmetric tornado circulation is described. The obtained profiles of vertical, radial and tangential velocities are in agreement with observations for the Mulhall tornado, world's largest on record and longest-lived among the three tornadoes for which 3D velocity data are available. Maximum possible vortex velocities are estimated. -- Highlights: → Water vapor condensation causes a logarithmic drop of air pressure towards tornado center. → The first ever theoretical description of tornado velocities is obtained. → The maximum vortex velocity grows logarithmically with decreasing tornado eye radius. → Air motion with high velocities can only develop in sufficiently large condensation areas.

  6. On the influence of microphone array geometry on HRTF-based Sound Source Localization

    DEFF Research Database (Denmark)

    Farmani, Mojtaba; Pedersen, Michael Syskind; Tan, Zheng-Hua

    2015-01-01

    . Furthermore, to demonstrate the analysis results, we show the impact of HRTFs similarities and microphone array geometry on an exemplary HRTF-based SSL algorithm, called MLSSL. This algorithm is well-suited for this purpose as it allows to estimate the Direction-of-Arrival (DoA) of the target sound using any......The direction dependence of Head Related Transfer Functions (HRTFs) forms the basis for HRTF-based Sound Source Localization (SSL) algorithms. In this paper, we show how spectral similarities of the HRTFs of different directions in the horizontal plane influence performance of HRTF-based SSL...

  7. Pseudo-Coherence-Based MVDR Beamformer for Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2015-01-01

    . This paper proposes minimum variance distortionless response filtering based on multichannel pseudo-coherence for speech enhancement with ad hoc microphone arrays. This method requires neither position information nor control of the trade-off used in the distortion weighted methods. Furthermore, certain...... performance criteria are derived in terms of the pseudo-coherence vector, and the method is compared with the multichannel Wiener filter. Evaluation shows the suitability of the proposed method in terms of noise reduction with minimum distortion in ad hoc scenarios....

  8. Reducing the impact of wind noise on cochlear implant processors with two microphones.

    Science.gov (United States)

    Kokkinakis, Kostas; Cox, Casey

    2014-05-01

    Behind-the-ear (BTE) processors of cochlear implant (CI) devices offer little to almost no protection from wind noise in most incidence angles. To assess speech intelligibility, eight CI recipients were tested in 3 and 9 m/s wind. Results indicated that speech intelligibility decreased substantially when the wind velocity, and in turn the wind sound pressure level, increased. A two-microphone wind noise suppression strategy was developed. Scores obtained with this strategy indicated substantial gains in speech intelligibility over other conventional noise reduction strategies tested.

  9. A Partitioned Approach to Signal Separation with Microphone Ad Hoc Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Benesty, Jacob

    2016-01-01

    In this paper, a blind algorithm is proposed for speech enhancement in multi-speaker scenarios, in which interference rejection is the main objective. Here, the ad hoc array is broken into microphone duples which are used to partition the array into local sub-arrays. The core algorithm takes...... advantage of differences in signal structure in each duple. A geometric mean filter is then used to merge the output signals obtained with different duples, and to form a global broadband maximum signal-to-interference ratio (SIR) enhancement apparatus. The resulting filter outputs are enhanced acoustic...

  10. Determining Sound Source Orientation from Source Directivity and Multi-microphone Recordings

    DEFF Research Database (Denmark)

    Guarato, Francesco; Hallam, John

    We present a method to estimate the orientation of a directional sound source and experimental results illustrating its performances. The method requires recordings captured by an array of microphones at known positions with respect to the source as well as the source directivity. Experiments have...... been performed in an ordinary environment by using a Polaroid transducer as the sound source emitting a broadband signal in the ultrasonic range. Such an acoustic signal has similar structure to those used by bats to echolocate. Results show that method is precise provided that the source directivity...

  11. Scrutinizing the pion condensed phase

    Energy Technology Data Exchange (ETDEWEB)

    Carignano, Stefano; Mammarella, Andrea; Mannarelli, Massimo [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Lepori, Luca [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Universita dell' Aquila, Dipartimento di Scienze Fisiche e Chimiche, Coppito-L' Aquila (Italy); Pagliaroli, Giulia [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Gran Sasso Science Institute, L' Aquila (Italy)

    2017-02-15

    When the isospin chemical potential exceeds the pion mass, charged pions condense in the zero-momentum state forming a superfluid. Chiral perturbation theory provides a very powerful tool for studying this phase. However, the formalism that is usually employed in this context does not clarify various aspects of the condensation mechanism and makes the identification of the soft modes problematic. We re-examine the pion condensed phase using different approaches within the chiral perturbation theory framework. As a first step, we perform a low-density expansion of the chiral Lagrangian valid close to the onset of the Bose-Einstein condensation. We obtain an effective theory that can be mapped to a Gross-Pitaevskii Lagrangian in which, remarkably, all the coefficients depend on the isospin chemical potential. The low-density expansion becomes unreliable deep in the pion condensed phase. For this reason, we develop an alternative field expansion deriving a low-energy Lagrangian analog to that of quantum magnets. By integrating out the ''radial'' fluctuations we obtain a soft Lagrangian in terms of the Nambu-Goldstone bosons arising from the breaking of the pion number symmetry. Finally, we test the robustness of the second-order transition between the normal and the pion condensed phase when next-to-leading-order chiral corrections are included. We determine the range of parameters for turning the second-order phase transition into a first-order one, finding that the currently accepted values of these corrections are unlikely to change the order of the phase transition. (orig.)

  12. Application of a circular 2D hard-sphere microphone array for higher-order Ambisonics auralization

    DEFF Research Database (Denmark)

    Weller, Tobias; Favrot, Sylvain Emmanuel; Buchholz, Jörg

    2011-01-01

    A circular microphone array mounted on a rigid sphere was realized and its application to higherorder Ambisonics (HOA) auralization was analysed. Besides the 2D Ambisonics application this array design provides a promising basis for the development of a mixed-order Ambisonics recording system......, in which the high spatial resolution of a high-order 2D system is efficiently combined with a periphonic sound field representation of a low-order 3D system. In order to evaluate and optimize the performance of the spherical 2D microphone array, a versatile simulation framework was developed, which...... included the entire processing path from the sound source via the (noisy) microphone signals and the loudspeaker output signals to the reproduced sound field in the centre of a loudspeaker array. This framework was then used to analyse the response of the different system stages to an ideal plane wave...

  13. Application of a circular 2D hard-sphere microphone array for higher-order Ambisonics auralization

    DEFF Research Database (Denmark)

    Weller, Tobias; Favrot, Sylvain Emmanuel; Buchholz, Jörg

    2011-01-01

    (dependent) parameters that mainly determine the balance between low frequency directionality, signal coloration and microphone noise amplification. The different stimuli were created with the framework using different values for both the array radius and the regularization coefficient lambda. It was shown......A circular microphone array mounted on a rigid sphere was realized and its application to higherorder Ambisonics (HOA) auralization was analysed. Besides the 2D Ambisonics application this array design provides a promising basis for the development of a mixed-order Ambisonics recording system......, in which the high spatial resolution of a high-order 2D system is efficiently combined with a periphonic sound field representation of a low-order 3D system. In order to evaluate and optimize the performance of the spherical 2D microphone array, a versatile simulation framework was developed, which...

  14. The chiral condensate in matter

    International Nuclear Information System (INIS)

    Brockmann, R.; Weise, W.

    1995-01-01

    The change of the chiral condensate in dense matter is discussed. Especially the higher order terms in the density of nuclear matter are evaluated (in the relativistic Brueckner-Hartree-Fock approach). Implications for nuclear physics and relativistic heavy ion collisions are discussed, such as the strong Dirac scalar mean field that results from the density dependence of . (orig.)

  15. KAON CONDENSATION IN NEUTRON STARS.

    Energy Technology Data Exchange (ETDEWEB)

    RAMOS,A.; SCHAFFNER-BIELICH,J.; WAMBACH,J.

    2001-04-24

    We discuss the kaon-nucleon interaction and its consequences for the change of the properties of the kaon in the medium. The onset of kaon condensation in neutron stars under various scenarios as well its effects for neutron star properties are reviewed.

  16. Approaching Bose-Einstein Condensation

    Science.gov (United States)

    Ferrari, Loris

    2011-01-01

    Bose-Einstein condensation (BEC) is discussed at the level of an advanced course of statistical thermodynamics, clarifying some formal and physical aspects that are usually not covered by the standard pedagogical literature. The non-conventional approach adopted starts by showing that the continuum limit, in certain cases, cancels out the crucial…

  17. Analysis and active compensation of microphonics in continuous wave narrow-bandwidth superconducting cavities

    Directory of Open Access Journals (Sweden)

    A. Neumann

    2010-08-01

    Full Text Available Many proposals for next generation light sources based on single pass free electron lasers or energy recovery linac facilities require a continuous wave (cw driven superconducting linac. The effective beam loading in such machines is very small and in principle the cavities can be operated at a bandwidth of a few Hz and with less than a few kW of rf power. However, a power reserve is required to ensure field stability. A major error source is the mechanical microphonics detuning of the niobium cavities. To understand the influence of cavity detuning on longitudinal beam stability, a measurement program has been started at the horizontal cavity test facility HoBiCaT at HZB to study TESLA-type cavities. The microphonics detuning spectral content, peak detuning values, and the driving terms for these mechanical oscillations have been analyzed. In combination with the characterization of cw-adapted fast tuning systems based on the piezoelectric effect this information has been used to design a detuning compensation algorithm. It has been shown that a compensation factor between 2–7 is achievable, reducing the typical detuning of 2–3 Hz rms to below 0.5 Hz rms. These results were included in rf-control simulations of the cavities, and it was demonstrated that a phase stability below 0.02° can be achieved.

  18. Estimation of Temporal Gait Parameters Using a Wearable Microphone-Sensor-Based System

    Directory of Open Access Journals (Sweden)

    Cheng Wang

    2016-12-01

    Full Text Available Most existing wearable gait analysis methods focus on the analysis of data obtained from inertial sensors. This paper proposes a novel, low-cost, wireless and wearable gait analysis system which uses microphone sensors to collect footstep sound signals during walking. This is the first time a microphone sensor is used as a wearable gait analysis device as far as we know. Based on this system, a gait analysis algorithm for estimating the temporal parameters of gait is presented. The algorithm fully uses the fusion of two feet footstep sound signals and includes three stages: footstep detection, heel-strike event and toe-on event detection, and calculation of gait temporal parameters. Experimental results show that with a total of 240 data sequences and 1732 steps collected using three different gait data collection strategies from 15 healthy subjects, the proposed system achieves an average 0.955 F1-measure for footstep detection, an average 94.52% accuracy rate for heel-strike detection and 94.25% accuracy rate for toe-on detection. Using these detection results, nine temporal related gait parameters are calculated and these parameters are consistent with their corresponding normal gait temporal parameters and labeled data calculation results. The results verify the effectiveness of our proposed system and algorithm for temporal gait parameter estimation.

  19. Adaptation to New Microphones Using Artificial Neural Networks With Trainable Activation Functions.

    Science.gov (United States)

    Siniscalchi, Sabato Marco; Salerno, Valerio Mario

    2017-08-01

    Model adaptation is a key technique that enables a modern automatic speech recognition (ASR) system to adjust its parameters, using a small amount of enrolment data, to the nuances in the speech spectrum due to microphone mismatch in the training and test data. In this brief, we investigate four different adaptation schemes for connectionist (also known as hybrid) ASR systems that learn microphone-specific hidden unit contributions, given some adaptation material. This solution is made possible adopting one of the following schemes: 1) the use of Hermite activation functions; 2) the introduction of bias and slope parameters in the sigmoid activation functions; 3) the injection of an amplitude parameter specific for each sigmoid unit; or 4) the combination of 2) and 3). Such a simple yet effective solution allows the adapted model to be stored in a small-sized storage space, a highly desirable property of adaptation algorithms for deep neural networks that are suitable for large-scale online deployment. Experimental results indicate that the investigated approaches reduce word error rates on the standard Spoke 6 task of the Wall Street Journal corpus compared with unadapted ASR systems. Moreover, the proposed adaptation schemes all perform better than simple multicondition training and comparable favorably against conventional linear regression-based approaches while using up to 15 orders of magnitude fewer parameters. The proposed adaptation strategies are also effective when a single adaptation sentence is available.

  20. Test-Retest Reliability of the Dual-Microphone Voice Range Profile.

    Science.gov (United States)

    Printz, Trine; Sorensen, Jesper Roed; Godballe, Christian; Grøntved, Ågot Møller

    2018-01-01

    The voice range profile (VRP) measures vocal intensity and fundamental frequency. Phonosurgical and logopedic treatment outcome studies using the VRP report voice improvements of 3-6 semitones (ST) in ST range and 4-7 decibels (dB) in sound pressure level range after treatment. These small improvements stress the importance of reliable measurements. The aim was to evaluate the test-retest reliability of the dual-microphone computerized VRP on participants with healthy voices. This is a prospective test-retest reliability study. Dual-microphone VRPs were repeated twice on healthy participants (n = 37) with an interval of 6-37 days. Voice frequency and intensity (minimum, maximum, and ranges) were assessed in combination with the area of the VRP. Correlations between VRP parameters were high (r > 0.60). However, in the retest, a statistically significant increase in voice frequency range (1.4 ST [95% confidence interval {CI}: 0.8-2.1 ST], P test and retest before the assessment is fully reliable for clinical application. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  1. DFT-domain based single-microphone noise reduction for speech enhancement a survey of the state of the art

    CERN Document Server

    Hendriks, Richard C; Jensen, Jesper

    2013-01-01

    As speech processing devices like mobile phones, voice controlled devices, and hearing aids have increased in popularity, people expect them to work anywhere and at any time without user intervention. However, the presence of acoustical disturbances limits the use of these applications, degrades their performance, or causes the user difficulties in understanding the conversation or appreciating the device. A common way to reduce the effects of such disturbances is through the use of single-microphone noise reduction algorithms for speech enhancement.The field of single-microphone noise reducti

  2. Microphone triggering circuit for elimination of mechanically induced frequency-jitter in diode laser spectrometers: implications for quantitative analysis.

    Science.gov (United States)

    Sams, R L; Fried, A

    1987-09-01

    An electronic timing circuit using a microphone triggering device has been developed for elimination of mechanically induced frequency-jitter in diode laser spectrometers employing closed-cycle refrigerators. Mechanical compressor piston shocks are detected by the microphone and actuate an electronic circuit which ultimately interrupts data acquisition until the mechanical vibrations are completely quenched. In this way, laser sweeps contaminated by compressor frequency-jitter are not co-averaged. Employing this circuit, measured linewidths were in better agreement with that calculated. The importance of eliminating this mechanically induced frequency-jitter when carrying out quantitative diode laser measurements is further discussed.

  3. Modeling of Kerena Emergency Condenser

    Science.gov (United States)

    Bryk, Rafał; Schmidt, Holger; Mull, Thomas; Wagner, Thomas; Ganzmann, Ingo; Herbst, Oliver

    2017-12-01

    KERENA is an innovative boiling water reactor concept equipped with several passive safety systems. For the experimental verification of performance of the systems and for codes validation, the Integral Test Stand Karlstein (INKA) was built in Karlstein, Germany. The emergency condenser (EC) system transfers heat from the reactor pressure vessel (RPV) to the core flooding pool in case of water level decrease in the RPV. EC is composed of a large number of slightly inclined tubes. During accident conditions, steam enters into the tubes and condenses due to the contact of the tubes with cold water at the secondary side. The condensed water flows then back to the RPV due to gravity. In this paper two approaches for modeling of condensation in slightly inclined tubes are compared and verified against experiments. The first approach is based on the flow regime map. Depending on the regime, heat transfer coefficient is calculated according to specific semi-empirical correlation. The second approach uses a general, fully-empirical correlation. The models are developed with utilization of the object-oriented Modelica language and the open-source OpenModelica environment. The results are compared with data obtained during a large scale integral test, simulating loss of coolant accident performed at Integral Test Stand Karlstein (INKA). The comparison shows a good agreement.Due to the modularity of models, both of them may be used in the future in systems incorporating condensation in horizontal or slightly inclined tubes. Depending on his preferences, the modeller may choose one-equation based approach or more sophisticated model composed of several exchangeable semi-empirical correlations.

  4. Modeling of Kerena Emergency Condenser

    Directory of Open Access Journals (Sweden)

    Bryk Rafał

    2017-12-01

    Full Text Available KERENA is an innovative boiling water reactor concept equipped with several passive safety systems. For the experimental verification of performance of the systems and for codes validation, the Integral Test Stand Karlstein (INKA was built in Karlstein, Germany. The emergency condenser (EC system transfers heat from the reactor pressure vessel (RPV to the core flooding pool in case of water level decrease in the RPV. EC is composed of a large number of slightly inclined tubes. During accident conditions, steam enters into the tubes and condenses due to the contact of the tubes with cold water at the secondary side. The condensed water flows then back to the RPV due to gravity. In this paper two approaches for modeling of condensation in slightly inclined tubes are compared and verified against experiments. The first approach is based on the flow regime map. Depending on the regime, heat transfer coefficient is calculated according to specific semi-empirical correlation. The second approach uses a general, fully-empirical correlation. The models are developed with utilization of the object-oriented Modelica language and the open-source OpenModelica environment. The results are compared with data obtained during a large scale integral test, simulating loss of coolant accident performed at Integral Test Stand Karlstein (INKA. The comparison shows a good agreement.Due to the modularity of models, both of them may be used in the future in systems incorporating condensation in horizontal or slightly inclined tubes. Depending on his preferences, the modeller may choose one-equation based approach or more sophisticated model composed of several exchangeable semi-empirical correlations.

  5. POTENTIAL DIMETHYLMERCURY CONCENTRATION IN WATER & ORGANIC CONDENSATE

    Energy Technology Data Exchange (ETDEWEB)

    MEACHAM, J.E.

    2004-12-28

    This document bounds potential dimethylmercury concentration in water or organic condensate that might form in ventilation systems or cooler tank regions. Dimethylmercury concentrations were extremely low and would be below drinking water standards in the water condensate.

  6. Some concepts in condensed phase chemical kinetics

    International Nuclear Information System (INIS)

    Adelman, S.A.

    1986-01-01

    Some concepts in condensed phase chemical kinetics which have emerged from a recent rigorous statistical mechanical treatment of condensed phase chemical reaction dynamics (S.A. Adelman, Adv. Chem. Phys.53:61 (1983)) are discussed in simple physical terms

  7. Pion condensation and neutron star dynamics

    International Nuclear Information System (INIS)

    Kaempfer, B.

    1983-01-01

    The question of formation of pion condensate via a phase transition in nuclear matter, especially in the core of neutron stars is reviewed. The possible mechanisms and the theoretical restrictions of pion condensation are summarized. The effects of ultradense equation of state and density jumps on the possible condensation phase transition are investigated. The possibilities of observation of condensation process are described. (D.Gy.)

  8. Condensed matter analogues of cosmology

    Science.gov (United States)

    Kibble, Tom; Srivastava, Ajit

    2013-10-01

    It is always exciting when developments in one branch of physics turn out to have relevance in a quite different branch. It would be hard to find two branches farther apart in terms of energy scales than early-universe cosmology and low-temperature condensed matter physics. Nevertheless ideas about the formation of topological defects during rapid phase transitions that originated in the context of the very early universe have proved remarkably fruitful when applied to a variety of condensed matter systems. The mathematical frameworks for describing these systems can be very similar. This interconnection has led to a deeper understanding of the phenomena in condensed matter systems utilizing ideas from cosmology. At the same time, one can view these condensed matter analogues as providing, at least in a limited sense, experimental access to the phenomena of the early universe for which no direct probe is possible. As this special issue well illustrates, this remains a dynamic and exciting field. The basic idea is that when a system goes through a rapid symmetry-breaking phase transition from a symmetric phase into one with spontaneously broken symmetry, the order parameter may make different choices in different regions, creating domains that when they meet can trap defects. The scale of those domains, and hence the density of defects, is constrained by the rate at which the system goes through the transition and the speed with which order parameter information propagates. This is what has come to be known as the Kibble-Zurek mechanism. The resultant scaling laws have now been tested in a considerable variety of different systems. The earliest experiments illustrating the analogy between cosmology and condensed matter were in liquid crystals, in particular on the isotropic-to-nematic transition, primarily because it is very easy to induce the phase transition (typically at room temperature) and to image precisely what is going on. This field remains one of the

  9. Charge Screening in a Charged Condensate

    International Nuclear Information System (INIS)

    Gabadadze, Gregory; Rosen, Rachel A.

    2009-01-01

    We consider a highly dense system of helium-4 nuclei and electrons in which the helium-4 nuclei have condensed. We present the condensation mechanism in the framework of low energy effective field theory and discuss the screening of electric charge in the condensate.

  10. Computations for a condenser. Experimental results

    International Nuclear Information System (INIS)

    Walden, Jean.

    1975-01-01

    Computations for condensers are presented with experimental results. The computations are concerned with the steam flux at the condenser input, and inside the tube bundle. Experimental results are given for the flux inside the condenser sleeve and the flow passing through the tube bundle [fr

  11. Direct, nondestructive observation of a Bose condensate

    NARCIS (Netherlands)

    Andrews, M.R.; Mewes, M.O.; van Druten, N.J.; Durfee, D.S.; Kurn, D.M.; Ketterle, W.

    1996-01-01

    The spatial observation of a Bose condensate is reported. Dispersive light scattering was used to observe the separation between the condensed and normal components of the Bose gas inside a magnetic trap. This technique is nondestructive, and about a hundred images of the same condensate can be

  12. Droplet size distribution in condensing flow

    NARCIS (Netherlands)

    Sidin, R.S.R.

    2009-01-01

    In this thesis, the problem of predicting the droplet size distribution in condensing ow is in- vestigated numerically and analytically. The work focuses on two types of problems: one where condensation occurs during the transonic expansion of a vapor-mixture, and a second one where condensation

  13. Modelling of film condensation in presence of non condensable gases

    International Nuclear Information System (INIS)

    Genevieve Geffraye; Dominique Bestion; Vladimir Kalitvianski

    2005-01-01

    Full text of publication follows: This paper presents recent developments in the modelling of the condensation due to heat removal from a wall with a possible presence of hydrogen, nitrogen, or air. This work is mainly concerned with nuclear reactor safety with particular reference to situations related to new reactor design, cold shutdown state and severe accident analysis. Film condensation of steam in presence of nitrogen and helium in a tube has been investigated in the COTURNE experiment in a rather large range of parameters, pressure (from 0.1 to 7 Mpa), heat flux (0.1 to 6 W/cm 2 ), mass fraction of noncondensable gas (0 to 1) and also in presence of superheated steam. The experiment represents a Steam Generator tube of a Pressurised Water Reactor and can simulate both co-current or countercurrent flow of steam and water.The models are implemented in the CATHARE code used for nuclear reactor thermal-hydraulics. The code uses two mass balance equations for liquid and gas, two momentum balance equations for liquid and gas and two energy balance equations for liquid and gas. Additional mass transport equations can be added for each non condensable gas. Heat transfers from wall to liquid film, from liquid to interface and gas to interface are modelled. The liquid film heat transfer coefficient is first investigated in pure saturated steam conditions in the pressure range from 0.1 to 7 Mpa. The CATHARE film condensation model in pure steam conditions is derived from Chen's correlation. Chen proposes a general correlation for the film condensation, covering the wavy-laminar and the turbulent film regimes and taking into account the interfacial friction effect. A large data base of laminar film regime was used including COTURNE data other available data found in the literature. The analysis of these data base suggests an influence of the liquid Reynolds number, according to the Nusselt theory, and also of the Eoetvoes number, with surface tension effects. A

  14. Fundamentals of condensed matter physics

    CERN Document Server

    Cohen, Marvin L

    2016-01-01

    Based on an established course and covering the fundamentals, central areas, and contemporary topics of this diverse field, Fundamentals of Condensed Matter Physics is a much-needed textbook for graduate students. The book begins with an introduction to the modern conceptual models of a solid from the points of view of interacting atoms and elementary excitations. It then provides students with a thorough grounding in electronic structure as a starting point to understand many properties of condensed matter systems - electronic, structural, vibrational, thermal, optical, transport, magnetic and superconductivity - and methods to calculate them. Taking readers through the concepts and techniques, the text gives both theoretically and experimentally inclined students the knowledge needed for research and teaching careers in this field. It features 200 illustrations, 40 worked examples and 150 homework problems for students to test their understanding. Solutions to the problems for instructors are available at w...

  15. LOFCON-LOFT condenser program

    International Nuclear Information System (INIS)

    Lemmon, E.C.; MacKay, D.B.

    1978-01-01

    LOFCON is a program developed for the LOFT air condenser system contained in the secondary coolant system. Although the basic theory described herein is general, the program given is not--it is specifically for the LOFT configuration. LOFCON is presented in subroutine form so that it may be easily incorporated into a larger program describing the complete secondary side. Specifically LOFCON was written to be incorporated into the detailed CSMP model of the LOFT secondary coolant system simulation

  16. LOFCON-LOFT condenser program

    Energy Technology Data Exchange (ETDEWEB)

    Lemmon, E.C.; MacKay, D.B.

    1978-05-26

    LOFCON is a program developed for the LOFT air condenser system contained in the secondary coolant system. Although the basic theory described herein is general, the program given is not--it is specifically for the LOFT configuration. LOFCON is presented in subroutine form so that it may be easily incorporated into a larger program describing the complete secondary side. Specifically LOFCON was written to be incorporated into the detailed CSMP model of the LOFT secondary coolant system simulation.

  17. Advances in condensed matter optics

    CERN Document Server

    Chen, Liangyao; Jiang, Xunya; Jin, Kuijuan; Liu, Hui; Zhao, Haibin

    2015-01-01

    This book describes some of the more recent progresses and developmentsin the study of condensed matter optics in both theoretic and experimental fields.It will help readers, especially graduate students and scientists who are studying and working in the nano-photonic field, to understand more deeply the characteristics of light waves propagated in nano-structure-based materials with potential applications in the future.

  18. Speech recognition in noise using bilateral open-fit hearing aids: the limited benefit of directional microphones and noise reduction.

    Science.gov (United States)

    Magnusson, Lennart; Claesson, Ann; Persson, Maria; Tengstrand, Tomas

    2013-01-01

    To investigate speech recognition performance in noise with bilateral open-fit hearing aids and as reference also with closed earmolds, in omnidirectional mode, directional mode, and directional mode in conjunction with noise reduction. A within-subject design with repeated measures across conditions was used. Speech recognition thresholds in noise were obtained for the different conditions. Twenty adults without prior experience with hearing aids. All had symmetric sensorineural mild hearing loss in the lower frequencies and moderate to severe hearing loss in the higher frequencies. Speech recognition performance in noise was not significantly better with an omnidirectional microphone compared to unaided, whereas performance was significantly better with a directional microphone (1.6 dB with open fitting and 4.4 dB with closed earmold) compared to unaided. With open fitting, no significant additional advantage was obtained by combining the directional microphone with a noise reduction algorithm, but with closed earmolds a significant additional advantage of 0.8 dB was obtained. The significant, though limited, advantage of directional microphones and the absence of additional significant improvement by a noise reduction algorithm should be considered when fitting open-fit hearing aids.

  19. FILTWAM - A Framework for Online Game-based Communication Skills Training - Using Webcams and Microphones for Enhancing Learner Support

    NARCIS (Netherlands)

    Bahreini, Kiavash; Nadolski, Rob; Qi, Wen; Westera, Wim

    2012-01-01

    Bahreini, K., Nadolski, R., Qi, W., & Westera, W. (2012). FILTWAM - A Framework for Online Game-based Communication Skills Training - Using Webcams and Microphones for Enhancing Learner Support. In P. Felicia (Ed.), The 6th European Conference on Games Based Learning - ECGBL 2012 (pp. 39-48). Cork,

  20. High frequency microphone measurements for transition detection on airfoils. Risø C2-18 appendix report

    DEFF Research Database (Denmark)

    Døssing, Mads

    Time series of pressure fluctuations has been obtained using high frequency microphones distributed over the surface of airfoils undergoing wind tunnel tests in the LM Windtunnel, owned by ’LM Glasfiber’, Denmark. The present report describes the dataanalysis, with special attention given to tran...

  1. High frequency microphone measurements for transition detection on airfoils. Risø B1-18 appendix report

    DEFF Research Database (Denmark)

    Døssing, Mads

    Time series of pressure fluctuations has been obtained using high frequency microphones distributed over the surface of airfoils undergoing wind tunnel tests in the LM Windtunnel, owned by ’LM Glasfiber’, Denmark. The present report describes the dataanalysis, with special attention given to tran...

  2. Accelerators for condensed matter research

    International Nuclear Information System (INIS)

    Williams, P.R.

    1990-01-01

    The requirement for high energy, high luminosity beams has stimulated the science and engineering of accelerators to a point where they open up opportunities for new areas of scientific application to benefit from the advances driven by particle physics. One area of great importance is the use of electron or positron storage rings as a source of intense VUV or X-ray synchrotron radiation. An accelerator application that has grown in prominence over the last 10 years has been spallation neutron sources. Neutrons offer an advantage over X-rays as a condensed matter probe because the neutron energy is usually of the same order as the room temperature thermal energy fluctuations in the sample being studied. Another area in which accelerators are playing an increasingly important role in condensed matter research concerns the use of Mu mesons, Muons, as a probe. This paper also presents a description of the ISIS Spallation Neutron Source. The design and status of the facility are described, and examples are given of its application to the study of condensed matter. (N.K.)

  3. Theory of laminar film condensation

    CERN Document Server

    Fujii, Tetsu

    1991-01-01

    Since the petroleum crisis in the 1970s, a lot of effort to save energy was made in industry, and remarkable achievements have been made. In the research and development concerning thermal energy, however, it was clar­ ified that one of the most important problems was manufacturing con­ densing systems with smaller size and higher performance. To solve this problem we need a method which synthesizes selections_ of the type of con­ denser, cooling tube and its arrangement, assessment of fouling on the cooling surfaces, consideration of transient characteristics of a condenser, etc. The majority of effort, however, has been to devise a surface element which enhances the heat transfer coefficient in condensation of a single or multicomponent vapor. Condensation phenomena are complexly affected by a lot of physical property values, and accordingly the results of theo­ retical research are expressed with several dimensionless parameters. On the other hand, the experimental research is limited to those with som...

  4. On the use of mobile phones and wearable microphones for noise exposure measurements: Calibration and measurement accuracy

    Science.gov (United States)

    Dumoulin, Romain

    Despite the fact that noise-induced hearing loss remains the number one occupational disease in developed countries, individual noise exposure levels are still rarely known and infrequently tracked. Indeed, efforts to standardize noise exposure levels present disadvantages such as costly instrumentation and difficulties associated with on site implementation. Given their advanced technical capabilities and widespread daily usage, mobile phones could be used to measure noise levels and make noise monitoring more accessible. However, the use of mobile phones for measuring noise exposure is currently limited due to the lack of formal procedures for their calibration and challenges regarding the measurement procedure. Our research investigated the calibration of mobile phone-based solutions for measuring noise exposure using a mobile phone's built-in microphones and wearable external microphones. The proposed calibration approach integrated corrections that took into account microphone placement error. The corrections were of two types: frequency-dependent, using a digital filter and noise level-dependent, based on the difference between the C-weighted noise level minus A-weighted noise level of the noise measured by the phone. The electro-acoustical limitations and measurement calibration procedure of the mobile phone were investigated. The study also sought to quantify the effect of noise exposure characteristics on the accuracy of calibrated mobile phone measurements. Measurements were carried out in reverberant and semi-anechoic chambers with several mobiles phone units of the same model, two types of external devices (an earpiece and a headset with an in-line microphone) and an acoustical test fixture (ATF). The proposed calibration approach significantly improved the accuracy of the noise level measurements in diffuse and free fields, with better results in the diffuse field and with ATF positions causing little or no acoustic shadowing. Several sources of errors

  5. Design of an Acoustic Target Intrusion Detection System Based on Small-Aperture Microphone Array

    Science.gov (United States)

    Zu, Xingshui; Guo, Feng; Huang, Jingchang; Zhao, Qin; Liu, Huawei; Li, Baoqing; Yuan, Xiaobing

    2017-01-01

    Automated surveillance of remote locations in a wireless sensor network is dominated by the detection algorithm because actual intrusions in such locations are a rare event. Therefore, a detection method with low power consumption is crucial for persistent surveillance to ensure longevity of the sensor networks. A simple and effective two-stage algorithm composed of energy detector (ED) and delay detector (DD) with all its operations in time-domain using small-aperture microphone array (SAMA) is proposed. The algorithm analyzes the quite different velocities between wind noise and sound waves to improve the detection capability of ED in the surveillance area. Experiments in four different fields with three types of vehicles show that the algorithm is robust to wind noise and the probability of detection and false alarm are 96.67% and 2.857%, respectively. PMID:28273838

  6. A novel vibration mode testing method for cylindrical resonators based on microphones.

    Science.gov (United States)

    Zhang, Yongmeng; Wu, Yulie; Wu, Xuezhong; Xi, Xiang; Wang, Jianqiu

    2015-01-16

    Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.

  7. Two-microphone separation of speech mixtures based on interclass variance maximization.

    Science.gov (United States)

    Cobos, Maximo; Lopez, Jose J

    2010-03-01

    Sparse methods for speech separation have become a discussed issue in acoustic signal processing. These sparse methods provide a powerful approach to the separation of several signals in the underdetermined case, i.e., when there are more sources than sensors. In this paper, a two-microphone separation method is presented. The proposed algorithm is based on grouping time-frequency points with similar direction-of-arrival (DOA) using a multi-level thresholding approach. The thresholds are calculated via the maximization of the interclass variance between DOA estimates and allow to identify angular sections, wherein the speakers are located with a strong likelihood. These sections define a set of time-frequency masks that are able to separate several sound sources in realistic scenarios and with little computational cost. Several experiments carried out under different mixing situations are discussed, showing the validity of the proposed approach.

  8. Note: Electronic damping of microphonics in superconducting resonators of a continuous wave linac

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Gopal [BARC, Mumbai 400085 (India); Sahu, Bhuban Kumar [IUAC, New Delhi 110067 (India); Agarwal, Vivek; Kumar, Girish [IITB, Mumbai 400076 (India)

    2014-02-15

    The paper presents an implementation technique to damp the microphonics in superconducting resonators utilizing the coupling between the electromagnetic and the mechanical modes of a resonator. In the technique used the resonant frequency variations are fed back to modulate the field amplitude through a suitable transfer function. Of the two transfer functions used in the experiments, one emulates a derivative action and is placed in a negative feedback configuration. The other transfer function is essentially a parallel combination of second order low pass filters and is used in a positive feedback configuration. Experiments with the Quarter Wave resonators of IUAC, New Delhi linac demonstrate that the damping of some of the modes increases significantly with the introduction of this feedback leading to a reduction in power required for field stabilization and quieter operation of the RF control system.

  9. Deconvolution for the localization of sound sources using a circular microphone array

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Jacobsen, Finn

    2013-01-01

    that the beamformer's point-spread function is shift-invariant. This makes it possible to apply computationally efficient deconvolution algorithms that consist of spectral procedures in the entire region of interest, such as the deconvolution approach for the mapping of the acoustic sources 2, the Fourier-based non......During the last decade, the aeroacoustic community has examined various methods based on deconvolution to improve the visualization of acoustic fields scanned with planar sparse arrays of microphones. These methods assume that the beamforming map in an observation plane can be approximated....... Even though these methods were originally designed for planar sparse arrays, in the present study, they are adapted to uniform circular arrays for mapping the sound over 360°. This geometry has the advantage that the beamforming output is practically independent of the focusing direction, meaning...

  10. Estimation of Road Vehicle Speed Using Two Omnidirectional Microphones: A Maximum Likelihood Approach

    Directory of Open Access Journals (Sweden)

    López-Valcarce Roberto

    2004-01-01

    Full Text Available We address the problem of estimating the speed of a road vehicle from its acoustic signature, recorded by a pair of omnidirectional microphones located next to the road. This choice of sensors is motivated by their nonintrusive nature as well as low installation and maintenance costs. A novel estimation technique is proposed, which is based on the maximum likelihood principle. It directly estimates car speed without any assumptions on the acoustic signal emitted by the vehicle. This has the advantages of bypassing troublesome intermediate delay estimation steps as well as eliminating the need for an accurate yet general enough acoustic traffic model. An analysis of the estimate for narrowband and broadband sources is provided and verified with computer simulations. The estimation algorithm uses a bank of modified crosscorrelators and therefore it is well suited to DSP implementation, performing well with preliminary field data.

  11. Design of an Acoustic Target Intrusion Detection System Based on Small-Aperture Microphone Array.

    Science.gov (United States)

    Zu, Xingshui; Guo, Feng; Huang, Jingchang; Zhao, Qin; Liu, Huawei; Li, Baoqing; Yuan, Xiaobing

    2017-03-04

    Automated surveillance of remote locations in a wireless sensor network is dominated by the detection algorithm because actual intrusions in such locations are a rare event. Therefore, a detection method with low power consumption is crucial for persistent surveillance to ensure longevity of the sensor networks. A simple and effective two-stage algorithm composed of energy detector (ED) and delay detector (DD) with all its operations in time-domain using small-aperture microphone array (SAMA) is proposed. The algorithm analyzes the quite different velocities between wind noise and sound waves to improve the detection capability of ED in the surveillance area. Experiments in four different fields with three types of vehicles show that the algorithm is robust to wind noise and the probability of detection and false alarm are 96.67% and 2.857%, respectively.

  12. A Novel Vibration Mode Testing Method for Cylindrical Resonators Based on Microphones

    Directory of Open Access Journals (Sweden)

    Yongmeng Zhang

    2015-01-01

    Full Text Available Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.

  13. In situ Probe Microphone Measurement for Testing the Direct Acoustical Cochlear Stimulator

    Directory of Open Access Journals (Sweden)

    Christof Stieger

    2017-08-01

    Full Text Available Hypothesis: Acoustical measurements can be used for functional control of a direct acoustic cochlear stimulator (DACS.Background: The DACS is a recently released active hearing implant that works on the principle of a conventional piston prosthesis driven by the rod of an electromagnetic actuator. An inherent part of the DACS actuator is a thin titanium diaphragm that allows for movement of the stimulation rod while hermetically sealing the housing. In addition to mechanical stimulation, the actuator emits sound into the mastoid cavity because of the motion of the diaphragm.Methods: We investigated the use of the sound emission of a DACS for intra-operative testing. We measured sound emission in the external auditory canal (PEAC and velocity of the actuators stimulation rod (Vact in five implanted ears of whole-head specimens. We tested the influence various positions of the loudspeaker and a probe microphone on PEAC and simulated implant malfunction in one example.Results: Sound emission of the DACS with a signal-to-noise ratio >10 dB was observed between 0.5 and 5 kHz. Simulated implant misplacement or malfunction could be detected by the absence or shift in the characteristic resonance frequency of the actuator. PEAC changed by <6 dB for variations of the microphone and loudspeaker position.Conclusion: Our data support the feasibility of acoustical measurements for in situ testing of the DACS implant in the mastoid cavity as well as for post-operative monitoring of actuator function.

  14. How to measure snoring? A comparison of the microphone, cannula and piezoelectric sensor.

    Science.gov (United States)

    Arnardottir, Erna S; Isleifsson, Bardur; Agustsson, Jon S; Sigurdsson, Gunnar A; Sigurgunnarsdottir, Magdalena O; Sigurđarson, Gudjon T; Saevarsson, Gudmundur; Sveinbjarnarson, Atli T; Hoskuldsson, Sveinbjorn; Gislason, Thorarinn

    2016-04-01

    The objective of this study was to compare to each other the methods currently recommended by the American Academy of Sleep Medicine (AASM) to measure snoring: an acoustic sensor, a piezoelectric sensor and a nasal pressure transducer (cannula). Ten subjects reporting habitual snoring were included in the study, performed at Landspitali-University Hospital, Iceland. Snoring was assessed by listening to the air medium microphone located on a patient's chest, compared to listening to two overhead air medium microphones (stereo) and manual scoring of a piezoelectric sensor and nasal cannula vibrations. The chest audio picked up the highest number of snore events of the different snore sensors. The sensitivity and positive predictive value of scoring snore events from the different sensors was compared to the chest audio: overhead audio (0.78, 0.98), cannula (0.55, 0.67) and piezoelectric sensor (0.78, 0.92), respectively. The chest audio was capable of detecting snore events with lower volume and higher fundamental frequency than the other sensors. The 200 Hz sampling rate of the cannula and piezoelectric sensor was one of their limitations for detecting snore events. The different snore sensors do not measure snore events in the same manner. This lack of consistency will affect future research on the clinical significance of snoring. Standardization of objective snore measurements is therefore needed. Based on this paper, snore measurements should be audio-based and the use of the cannula as a snore sensor be discontinued, but the piezoelectric sensor could possibly be modified for improvement. © 2015 European Sleep Research Society.

  15. Universal Themes of Bose-Einstein Condensation

    Science.gov (United States)

    Proukakis, Nick P.; Snoke, David W.; Littlewood, Peter B.

    2017-04-01

    Foreword; List of contributors; Preface; Part I. Introduction: 1. Universality and Bose-Einstein condensation: perspectives on recent work D. W. Snoke, N. P. Proukakis, T. Giamarchi and P. B. Littlewood; 2. A history of Bose-Einstein condensation of atomic hydrogen T. Greytak and D. Kleppner; 3. Twenty years of atomic quantum gases: 1995-2015 W. Ketterle; 4. Introduction to polariton condensation P. B. Littlewood and A. Edelman; Part II. General Topics: Editorial notes; 5. The question of spontaneous symmetry breaking in condensates D. W. Snoke and A. J. Daley; 6. Effects of interactions on Bose-Einstein condensation R. P. Smith; 7. Formation of Bose-Einstein condensates M. J. Davis, T. M. Wright, T. Gasenzer, S. A. Gardiner and N. P. Proukakis; 8. Quenches, relaxation and pre-thermalization in an isolated quantum system T. Langen and J. Schmiedmayer; 9. Ultracold gases with intrinsic scale invariance C. Chin; 10. Berezinskii-Kosterlitz-Thouless phase of a driven-dissipative condensate N. Y. Kim, W. H. Nitsche and Y. Yamamoto; 11. Superfluidity and phase correlations of driven dissipative condensates J. Keeling, L. M. Sieberer, E. Altman, L. Chen, S. Diehl and J. Toner; 12. BEC to BCS crossover from superconductors to polaritons A. Edelman and P. B. Littlewood; Part III. Condensates in Atomic Physics: Editorial notes; 13. Probing and controlling strongly correlated quantum many-body systems using ultracold quantum gases I. Bloch; 14. Preparing and probing chern bands with cold atoms N. Goldman, N. R. Cooper and J. Dalibard; 15. Bose-Einstein condensates in artificial gauge fields L. J. LeBlanc and I. B. Spielman; 16. Second sound in ultracold atomic gases L. Pitaevskii and S. Stringari; 17. Quantum turbulence in atomic Bose-Einstein condensates N. G. Parker, A. J. Allen, C. F. Barenghi and N. P. Proukakis; 18. Spinor-dipolar aspects of Bose-Einstein condensation M. Ueda; Part IV. Condensates in Condensed Matter Physics: Editorial notes; 19. Bose

  16. Condensation on slippery asymmetric bumps

    Science.gov (United States)

    Park, Kyoo-Chul; Kim, Philseok; Grinthal, Alison; He, Neil; Fox, David; Weaver, James C.; Aizenberg, Joanna

    2016-03-01

    Controlling dropwise condensation is fundamental to water-harvesting systems, desalination, thermal power generation, air conditioning, distillation towers, and numerous other applications. For any of these, it is essential to design surfaces that enable droplets to grow rapidly and to be shed as quickly as possible. However, approaches based on microscale, nanoscale or molecular-scale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach—based on principles derived from Namib desert beetles, cacti, and pitcher plants—that synergistically combines these aspects of condensation and substantially outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle’s bumpy surface geometry in promoting condensation, and using theoretical modelling, we show how to maximize vapour diffusion fluxat the apex of convex millimetric bumps by optimizing the radius of curvature and cross-sectional shape. Integrating this apex geometry with a widening slope, analogous to cactus spines, directly couples facilitated droplet growth with fast directional transport, by creating a free-energy profile that drives the droplet down the slope before its growth rate can decrease. This coupling is further enhanced by a slippery, pitcher-plant-inspired nanocoating that facilitates feedback between coalescence-driven growth and capillary-driven motion on the way down. Bumps that are rationally designed to integrate these mechanisms are able to grow and transport large droplets even against gravity and overcome the effect of an unfavourable temperature gradient. We further observe an unprecedented sixfold-higher exponent of growth rate, faster onset, higher steady-state turnover rate, and a greater volume of water collected compared to other surfaces. We envision that this fundamental understanding and rational design strategy can be

  17. Measurements of noise immission from wind turbines at receptor locations: Use of a vertical microphone board to improve the signal-to-noise ratio

    International Nuclear Information System (INIS)

    Fegeant, Olivier

    1999-01-01

    The growing interest in wind energy has increased the need of accuracy in wind turbine noise immission measurements and thus, the need of new measurement techniques. This paper shows that mounting the microphone on a vertical board improves the signal-to-noise ratio over the whole frequency range compared to the free microphone technique. Indeed, the wind turbine is perceived two times noisier by the microphone due to the signal reflection by the board while, in addition, the wind noise is reduced. Furthermore, the board shielding effect allows the measurements to be carried out in the presence of reflecting surfaces such as building facades

  18. Quantum tunnelling in condensed media

    CERN Document Server

    Kagan, Yu

    1992-01-01

    The essays in this book deal with of the problem of quantum tunnelling and related behavior of a microscopic or macroscopic system, which interacts strongly with an ""environment"" - this being some form of condensed matter. The ""system"" in question need not be physically distinct from its environment, but could, for example, be one particular degree of freedom on which attention is focussed, as in the case of the Josephson junction studied in several of the papers. This general problem has been studied in many hundreds, if not thousands, of articles in the literature, in contexts as diverse

  19. On scalar condensate baryogenesis model

    International Nuclear Information System (INIS)

    Kiriloval, D.P.; Valchanov, T.V.

    2004-09-01

    We discuss the scalar field condensate baryogenesis model, which is among the baryogenesis scenarios preferred today, compatible with inflation. According to that model a complex scalar field φ, carrying baryon charge B≠0 is generated at inflation. The baryon excess in the Universe results from the φ decay at later stages of Universe evolution (T 15 GeV). We updated the model's parameters range according to the current observational cosmological constraints and analyzed numerically φ evolution after the inflationary stage till its decay φ → qq-barlγ. During that period oscillated with a decreasing amplitude due to Universe expansion and particle production processes due to the coupling of the field to fermions gφf 1 f 2 . It was shown that particle creation processes play an essential role for evolution and its final value. It may lead to a considerable decrease of the field's amplitude for large g and/or large H values, which reflects finally into strong damping of the baryon charge carried by the condensate. The analysis suggests that for a natural range of the model's parameters the observed value of the baryon asymmetry can be obtained and the model can serve as a successful baryogenesis model, compatible with inflation. (author)

  20. Condensation induced water hammer safety

    Energy Technology Data Exchange (ETDEWEB)

    Gintner, M.A.

    1997-03-10

    Condensation induced water hammer events in piping systems can cause catastrophic steam system failures which can result in equipment damage, personal injury, and even death. As an industry, we have learned to become accustomed to the ''banging'' that we often hear in our steam piping systems, and complacent in our actions to prevent it. It is unfortunate that lives are lost needlessly, as this type of water hammer event is preventable if one only applies some basic principles when operating and maintaining their steam systems. At the U. S. Department of Energy's Hanford Site where I work, there was one such accident that occurred in 1993 which took the life of a former co-worker and friend of mine. Hanford was established as part of the Manhattan Project during World War II. it is a 560 square mile complex located along the banks of the Columbia River in Southeastern Washington State. For almost 45 years, hanford's mission was to produce weapons grade plutonium for our nations defense programs. Today, Hanford no longer produces plutonium, but is focused on site clean-up and economic diversification. Hanford still uses steam for heating and processing activities, utilizing over 20 miles of piping distribution systems similar to those found in industry. Although these aging systems are still sound, they cannot stand up to the extreme pressure pulses developed by a condensation induced water hammer.

  1. Muonic Chemistry in Condensed Matter

    CERN Multimedia

    2002-01-01

    When polarized muons (@m|+) stop in condensed matter, muonic atoms are formed in the final part of their range, and direct measurements of the @m|+-spin polarization are possible via the asymmetric decay into positrons. The hyperfine interaction determines the characteristic precession frequencies of the @m|+ spin in muonium, @w(Mu). Such frequencies can be altered by the interactions of the muonium's electron spin with the surrounding medium. The measurement of @w(Mu) in a condensed system is known often to provide unique information regarding the system. \\\\ \\\\ In particular, the use of muonium atoms as a light isotope of the simple reactive radical H|0 allows the investigation of fast reactions of radicals over a typical time scale 10|-|9~@$<$~t~@$<$~10|-|5~sec, which is determined by the instrumental resolution at one end and by the @m|+ lifetime at the other. \\\\ \\\\ In biological macromolecules transient radicals, such as the constituents of DNA itself, exist on a time scale of sub-microseconds, acco...

  2. Magnon condensation and spin superfluidity

    Science.gov (United States)

    Bunkov, Yury M.; Safonov, Vladimir L.

    2018-04-01

    We consider the Bose-Einstein condensation (BEC) of quasi-equilibrium magnons which leads to spin superfluidity, the coherent quantum transfer of magnetization in magnetic material. The critical conditions for excited magnon density in ferro- and antiferromagnets, bulk and thin films, are estimated and discussed. It was demonstrated that only the highly populated region of the spectrum is responsible for the emergence of any BEC. This finding substantially simplifies the BEC theoretical analysis and is surely to be used for simulations. It is shown that the conditions of magnon BEC in the perpendicular magnetized YIG thin film is fulfillied at small angle, when signals are treated as excited spin waves. We also predict that the magnon BEC should occur in the antiferromagnetic hematite at room temperature at much lower excited magnon density compared to that of ferromagnetic YIG. Bogoliubov's theory of Bose-Einstein condensate is generalized to the case of multi-particle interactions. The six-magnon repulsive interaction may be responsible for the BEC stability in ferro- and antiferromagnets where the four-magnon interaction is attractive.

  3. Condensation induced water hammer safety

    International Nuclear Information System (INIS)

    Gintner, M.A.

    1997-01-01

    Condensation induced water hammer events in piping systems can cause catastrophic steam system failures which can result in equipment damage, personal injury, and even death. As an industry, we have learned to become accustomed to the ''banging'' that we often hear in our steam piping systems, and complacent in our actions to prevent it. It is unfortunate that lives are lost needlessly, as this type of water hammer event is preventable if one only applies some basic principles when operating and maintaining their steam systems. At the U. S. Department of Energy's Hanford Site where I work, there was one such accident that occurred in 1993 which took the life of a former co-worker and friend of mine. Hanford was established as part of the Manhattan Project during World War II. it is a 560 square mile complex located along the banks of the Columbia River in Southeastern Washington State. For almost 45 years, hanford's mission was to produce weapons grade plutonium for our nations defense programs. Today, Hanford no longer produces plutonium, but is focused on site clean-up and economic diversification. Hanford still uses steam for heating and processing activities, utilizing over 20 miles of piping distribution systems similar to those found in industry. Although these aging systems are still sound, they cannot stand up to the extreme pressure pulses developed by a condensation induced water hammer

  4. Bio-oil fractionation and condensation

    Science.gov (United States)

    Brown, Robert C; Jones, Samuel T; Pollard, Anthony

    2013-07-02

    A method of fractionating bio-oil vapors which involves providing bio-oil vapors comprising bio-oil constituents is described. The bio-oil vapors are cooled in a first stage which comprises a condenser having passages for the bio-oil separated by a heat conducting wall from passages for a coolant. The coolant in the condenser of the first stage is maintained at a substantially constant temperature, set at a temperature in the range of 75 to 100.degree. C., to condense a first liquid fraction of liquefied bio-oil constituents in the condenser of the first stage. The first liquid fraction of liquified bio-oil constituents from the condenser in the first stage is collected. Also described are steps for subsequently recovering further liquid fractions of liquefied bio-oil constituents. Particular compositions of bio-oil condensation products are also described.

  5. The physics of exciton-polariton condensates

    CERN Document Server

    Lagoudakis, Konstantinos

    2013-01-01

    In 2006 researchers created the first polariton Bose-Einstein condensate at 19K in the solid state. Being inherently open quantum systems, polariton condensates open a window into the unpredictable world of physics beyond the “fifth state of matter”: the limited lifetime of polaritons renders polariton condensates out-of-equilibrium and provides a fertile test-bed for non-equilibrium physics. This book presents an experimental investigation into exciting features arising from this non-equilibrium behavior. Through careful experimentation, the author demonstrates the ability of polaritons to synchronize and create a single energy delocalized condensate. Under certain disorder and excitation conditions the complete opposite case of coexisting spatially overlapping condensates may be observed. The author provides the first demonstration of quantized vortices in polariton condensates and the first observation of fractional vortices with full phase and amplitude characterization. Finally, this book investigate...

  6. THE STABILITY OF VAPOR CONDENSATION EQUILIBRIUM

    OpenAIRE

    SHIMIN ZHANG

    2005-01-01

    The system must get across an energy peak of unstable equilibrium during the condensation of pure vapor; as the supersaturated extent of vapor increases and the temperature decreases, the energy peak shortens and vapor condensation becomes easier. The system must get across an energy peak of unstable equilibrium first, and then get into an energy valley of stable equilibrium during the condensation of impure vapor; as the partial pressure of vapor decreases, the energy peak becomes taller, th...

  7. Nonlinear behavior of the radiative condensation instability

    International Nuclear Information System (INIS)

    McCarthy, D.; Drake, J.F.

    1991-01-01

    An investigation of the nonlinear behavior of the radiative condensation instability is presented in a simple one-dimensional magnetized plasma. It is shown that the radiative condensation is typically a nonlinear instability---the growth of the instability is stronger once the disturbance reaches finite amplitude. Moreover, classical parallel thermal conduction is insufficient by itself to saturate the instability. Radiative collapse continues until the temperature in the high density condensation falls sufficiently to reduce the radiation rate

  8. Physics of hollow Bose-Einstein condensates

    OpenAIRE

    Padavić, Karmela; Sun, Kuei; Lannert, Courtney; Vishveshwara, Smitha

    2016-01-01

    Bose-Einstein condensate shells, while occurring in ultracold systems of coexisting phases and potentially within neutron stars, have yet to be realized in isolation on Earth due to the experimental challenge of overcoming gravitational sag. Motivated by the expected realization of hollow condensates by the space-based Cold Atomic Laboratory in microgravity conditions, we study a spherical condensate undergoing a topological change from a filled sphere to a hollow shell. We argue that the col...

  9. Advances in modelling of condensation phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.S.; Zaltsgendler, E. [Ontario Hydro Nuclear, Toronto (Canada); Hanna, B. [Atomic Energy of Canada Limited, Pinawa, Manitoba (Canada)

    1997-07-01

    The physical parameters in the modelling of condensation phenomena in the CANDU reactor system codes are discussed. The experimental programs used for thermal-hydraulic code validation in the Canadian nuclear industry are briefly described. The modelling of vapour generation and in particular condensation plays a key role in modelling of postulated reactor transients. The condensation models adopted in the current state-of-the-art two-fluid CANDU reactor thermal-hydraulic system codes (CATHENA and TUF) are described. As examples of the modelling challenges faced, the simulation of a cold water injection experiment by CATHENA and the simulation of a condensation induced water hammer experiment by TUF are described.

  10. Strangeness condensation and ''clearing'' of the vacuum

    International Nuclear Information System (INIS)

    Brown, G.E.; Kubodera, Kuniharu; Rho, M.; State Univ. of New York, Stony Brook

    1987-01-01

    We show that a substantial amount of strange quark-antiquark pair condensates in the nucleon required by the πN sigma term implies that kaons could condense in nuclear matter at a density about three times that of normal nuclear matter. This phenomenon can be understood as the ''cleansing'' of qanti q condensates from the QCD vacuum by a dense nuclear matter, resulting in a (partial) restoration of the chiral symmetry explicitly broken in the vacuum. It is suggested that the condensation signals a new phase distinct from that of quark plasma and that of ordinary dense hadronic matter. (orig.)

  11. Compensating microphonics in SRF cavities to ensure beam stability for future free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Axel

    2008-07-21

    In seeded High-Gain-Harmonic-Generation free electron lasers or energy recovery linear accelerators the requirements for the bunch-to-bunch timing and energy jitter of the beam are in the femtosecond and per mill regime. This implies the ability to control the cavity radiofrequency (RF) field to an accuracy of 0.02 in phase and up to 1.10{sup -4} in amplitude. For the planned BESSY-FEL it is envisaged to operate 144 superconducting 1.3 GHz cavities of the 2.3 GeV driver linac in continuous wave mode and at a low beam current. The cavity resonance comprises a very narrow bandwidth of the order of tens of Hertz. Such cavities have been characterized under accelerator like conditions in the HoBiCaT test facility. It was possible to measure the error sources affecting the field stability in continuous wave (CW) operation. Microphonics, the main error source for a mechanical detuning of the cavities, lead to an average fluctuation of the cavity resonance of 1-5 Hz rms. Furthermore, the static and dynamic Lorentz force detuning and the helium pressure dependance of the cavity resonance have been measured. Single cavity RF control and linac bunch-to-bunch longitudinal phase space modeling containing the measured properties showed, that it is advisable to find means to minimize the microphonics detuning by mechanical tuning. Thus, several fast tuning systems have been tested for CW operation. These tuners consist of a motor driven lever for slow and coarse tuning and a piezo that is integrated into the tuner support for fast and fine tuning. Regarding the analysis of the detuning spectrum an adaptive feedforward method based on the least-mean-square filter algorithm has been developed for fast cavity tuning. A detuning compensation between a factor of two and up to a factor of seven has been achieved. Modeling the complete system including the fast tuning scheme, showed that the requirements of the BESSY-FEL are attainable. (orig.)

  12. Nanogenerator-based dual-functional and self-powered thin patch loudspeaker or microphone for flexible electronics

    Science.gov (United States)

    Li, Wei; Torres, David; Díaz, Ramón; Wang, Zhengjun; Wu, Changsheng; Wang, Chuan; Lin Wang, Zhong; Sepúlveda, Nelson

    2017-05-01

    Ferroelectret nanogenerators were recently introduced as a promising alternative technology for harvesting kinetic energy. Here we report the device's intrinsic properties that allow for the bidirectional conversion of energy between electrical and mechanical domains; thus extending its potential use in wearable electronics beyond the power generation realm. This electromechanical coupling, combined with their flexibility and thin film-like form, bestows dual-functional transducing capabilities to the device that are used in this work to demonstrate its use as a thin, wearable and self-powered loudspeaker or microphone patch. To determine the device's performance and applicability, sound pressure level is characterized in both space and frequency domains for three different configurations. The confirmed device's high performance is further validated through its integration in three different systems: a music-playing flag, a sound recording film and a flexible microphone for security applications.

  13. Doppler distortion correction based on microphone array and matching pursuit algorithm for a wayside train bearing monitoring system

    International Nuclear Information System (INIS)

    Liu, Xingchen; Hu, Zhiyong; He, Qingbo; Zhang, Shangbin; Zhu, Jun

    2017-01-01

    Doppler distortion and background noise can reduce the effectiveness of wayside acoustic train bearing monitoring and fault diagnosis. This paper proposes a method of combining a microphone array and matching pursuit algorithm to overcome these difficulties. First, a dictionary is constructed based on the characteristics and mechanism of a far-field assumption. Then, the angle of arrival of the train bearing is acquired when applying matching pursuit to analyze the acoustic array signals. Finally, after obtaining the resampling time series, the Doppler distortion can be corrected, which is convenient for further diagnostic work. Compared with traditional single-microphone Doppler correction methods, the advantages of the presented array method are its robustness to background noise and its barely requiring pre-measuring parameters. Simulation and experimental study show that the proposed method is effective in performing wayside acoustic bearing fault diagnosis. (paper)

  14. Interface for Barge-in Free Spoken Dialogue System Based on Sound Field Reproduction and Microphone Array

    Directory of Open Access Journals (Sweden)

    Hinamoto Yoichi

    2007-01-01

    Full Text Available A barge-in free spoken dialogue interface using sound field control and microphone array is proposed. In the conventional spoken dialogue system using an acoustic echo canceller, it is indispensable to estimate a room transfer function, especially when the transfer function is changed by various interferences. However, the estimation is difficult when the user and the system speak simultaneously. To resolve the problem, we propose a sound field control technique to prevent the response sound from being observed. Combined with a microphone array, the proposed method can achieve high elimination performance with no adaptive process. The efficacy of the proposed interface is ascertained in the experiments on the basis of sound elimination and speech recognition.

  15. A mathematical model for source separation of MMG signals recorded with a coupled microphone-accelerometer sensor pair.

    Science.gov (United States)

    Silva, Jorge; Chau, Tom

    2005-09-01

    Recent advances in sensor technology for muscle activity monitoring have resulted in the development of a coupled microphone-accelerometer sensor pair for physiological acousti signal recording. This sensor can be used to eliminate interfering sources in practical settings where the contamination of an acoustic signal by ambient noise confounds detection but cannot be easily removed [e.g., mechanomyography (MMG), swallowing sounds, respiration, and heart sounds]. This paper presents a mathematical model for the coupled microphone-accelerometer vibration sensor pair, specifically applied to muscle activity monitoring (i.e., MMG) and noise discrimination in externally powered prostheses for below-elbow amputees. While the model provides a simple and reliable source separation technique for MMG signals, it can also be easily adapted to other aplications where the recording of low-frequency (< 1 kHz) physiological vibration signals is required.

  16. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: NEW CONDENSATOR, INC.--THE CONDENSATOR DIESEL ENGINE RETROFIT CRANKCASE VENTILATION SYSTEM

    Science.gov (United States)

    EPA's Environmental Technology Verification Program has tested New Condensator Inc.'s Condensator Diesel Engine Retrofit Crankcase Ventilation System. Brake specific fuel consumption (BSFC), the ratio of engine fuel consumption to the engine power output, was evaluated for engine...

  17. Determining Sound Source Orientation from Source Directivity and Real Multi-Microphone Recordings: Experimental Comparisons using both Analytical and Measured Directivity Models

    DEFF Research Database (Denmark)

    Guarato, Francesco; Hallam, John; Vanderelst, Dieter

    2009-01-01

    This paper presents a method for estimating the orientation of a directional sound source emitting a broadband acoustic signal being recorded by a microphone array, given source directivity, microphone positions with respect to the source and recordings of the call. Such a method has been tested ....... The signal emitted by the source is broadband, like the signals many bats use while echolocating. Indeed, our intended final application of the method is to estimate the orientations a bat assumes while hunting over water....

  18. Quasiparticles in condensed matter systems

    Science.gov (United States)

    Wölfle, Peter

    2018-03-01

    Quasiparticles are a powerful concept of condensed matter quantum theory. In this review, the appearence and the properties of quasiparticles are presented in a unifying perspective. The principles behind the existence of quasiparticle excitations in both quantum disordered and ordered phases of fermionic and bosonic systems are discussed. The lifetime of quasiparticles is considered in particular near a continuous classical or quantum phase transition, when the nature of quasiparticles on both sides of a transition into an ordered state changes. A new concept of critical quasiparticles near a quantum critical point is introduced, and applied to quantum phase transitions in heavy fermion metals. Fractional quasiparticles in systems of restricted dimensionality are reviewed. Dirac quasiparticles emerging in so-called Dirac materials are discussed. The more recent discoveries of topologically protected chiral quasiparticles in topological matter and Majorana quasiparticles in topological superconductors are briefly reviewed.

  19. Possibility of removing condensate and scattered oil from gas-condensate field during bed flooding

    Energy Technology Data Exchange (ETDEWEB)

    Belkina, N.A.; Yagubov, M.S.

    1984-01-01

    The problem is set of evaluating the possible removal from the bed of scattered oil and condensate during flooding of the bed. For this purpose, an experimental study was made of the displacement by water from the porous medium of the oil and condensate saturating it. The obtained experimental results permit evaluation of the possible removal from the gas-condensate bed of scattered oil and condensate during flooding of the bed.

  20. Statistical physics and condensed matter

    International Nuclear Information System (INIS)

    2003-01-01

    This document is divided into 4 sections: 1) General aspects of statistical physics. The themes include: possible geometrical structures of thermodynamics, the thermodynamical foundation of quantum measurement, transport phenomena (kinetic theory, hydrodynamics and turbulence) and out of equilibrium systems (stochastic dynamics and turbulence). The techniques involved here are typical of applied analysis: stability criteria, mode decomposition, shocks and stochastic equations. 2) Disordered, glassy and granular systems: statics and dynamics. The complexity of the systems can be studied through the structure of their phase space. The geometry of this phase space is studied in several works: the overlap distribution can now be computed with a very high precision; the boundary energy between low lying states does not behave like in ordinary systems; and the Edward's hypothesis of equi-probability of low lying metastable states is invalidated. The phenomenon of aging, characteristic of glassy dynamics, is studied in several models. Dynamics of biological systems or of fracture is shown to bear some resemblance with that of disordered systems. 3) Quantum systems. The themes include: mesoscopic superconductors, supersymmetric approach to strongly correlated electrons, quantum criticality and heavy fermion compounds, optical sum rule violation in the cuprates, heat capacity of lattice spin models from high-temperature series expansion, Lieb-Schultz-Mattis theorem in dimension larger than one, quantum Hall effect, Bose-Einstein condensation and multiple-spin exchange model on the triangular lattice. 4) Soft condensed matter and biological systems. Path integral representations are invaluable to describe polymers, proteins and self-avoiding membranes. Using these methods, problems as diverse as the titration of a weak poly-acid by a strong base, the denaturation transition of DNA or bridge-hopping in conducting polymers have been addressed. The problems of RNA folding has

  1. SoundCompass: a distributed MEMS microphone array-based sensor for sound source localization.

    Science.gov (United States)

    Tiete, Jelmer; Domínguez, Federico; da Silva, Bruno; Segers, Laurent; Steenhaut, Kris; Touhafi, Abdellah

    2014-01-23

    Sound source localization is a well-researched subject with applications ranging from localizing sniper fire in urban battlefields to cataloging wildlife in rural areas. One critical application is the localization of noise pollution sources in urban environments, due to an increasing body of evidence linking noise pollution to adverse effects on human health. Current noise mapping techniques often fail to accurately identify noise pollution sources, because they rely on the interpolation of a limited number of scattered sound sensors. Aiming to produce accurate noise pollution maps, we developed the SoundCompass, a low-cost sound sensor capable of measuring local noise levels and sound field directionality. Our first prototype is composed of a sensor array of 52 Microelectromechanical systems (MEMS) microphones, an inertial measuring unit and a low-power field-programmable gate array (FPGA). This article presents the SoundCompass's hardware and firmware design together with a data fusion technique that exploits the sensing capabilities of the SoundCompass in a wireless sensor network to localize noise pollution sources. Live tests produced a sound source localization accuracy of a few centimeters in a 25-m2 anechoic chamber, while simulation results accurately located up to five broadband sound sources in a 10,000-m2 open field.

  2. Numerical Analysis of CNC Milling Chatter Using Embedded Miniature MEMS Microphone Array System

    Directory of Open Access Journals (Sweden)

    Pang-Li Wang

    2018-01-01

    Full Text Available With the increasingly common use of industrial automation for mass production, there are many computer numerical control (CNC machine tools that require the collection of data from intelligent sensors in order to analyze their processing quality. In general, for high speed rotating machines, an accelerometer can be attached on the spindle to collect the data from the detected vibration of the CNC. However, due to their cost, accelerometers have not been widely adopted for use with typical CNC machine tools. This study sought to develop an embedded miniature MEMS microphone array system (Radius 5.25 cm, 8 channels to discover the vibration source of the CNC from spatial phase array processing. The proposed method utilizes voice activity detection (VAD to distinguish between the presence and absence of abnormal noise in the pre-stage, and utilizes the traditional direction of arrival method (DOA via multiple signal classification (MUSIC to isolate the spatial orientation of the noise source in post-processing. In the numerical simulation, the non-interfering noise source location is calibrated in the anechoic chamber, and is tested with real milling processing in the milling machine. As this results in a high background noise level, the vibration sound source is more accurate in the presented energy gradation graphs as compared to the traditional MUSIC method.

  3. A reverberation-time-aware DNN approach leveraging spatial information for microphone array dereverberation

    Science.gov (United States)

    Wu, Bo; Yang, Minglei; Li, Kehuang; Huang, Zhen; Siniscalchi, Sabato Marco; Wang, Tong; Lee, Chin-Hui

    2017-12-01

    A reverberation-time-aware deep-neural-network (DNN)-based multi-channel speech dereverberation framework is proposed to handle a wide range of reverberation times (RT60s). There are three key steps in designing a robust system. First, to accomplish simultaneous speech dereverberation and beamforming, we propose a framework, namely DNNSpatial, by selectively concatenating log-power spectral (LPS) input features of reverberant speech from multiple microphones in an array and map them into the expected output LPS features of anechoic reference speech based on a single deep neural network (DNN). Next, the temporal auto-correlation function of received signals at different RT60s is investigated to show that RT60-dependent temporal-spatial contexts in feature selection are needed in the DNNSpatial training stage in order to optimize the system performance in diverse reverberant environments. Finally, the RT60 is estimated to select the proper temporal and spatial contexts before feeding the log-power spectrum features to the trained DNNs for speech dereverberation. The experimental evidence gathered in this study indicates that the proposed framework outperforms the state-of-the-art signal processing dereverberation algorithm weighted prediction error (WPE) and conventional DNNSpatial systems without taking the reverberation time into account, even for extremely weak and severe reverberant conditions. The proposed technique generalizes well to unseen room size, array geometry and loudspeaker position, and is robust to reverberation time estimation error.

  4. Infrastructure-Less Indoor Localization Using the Microphone, Magnetometer and Light Sensor of a Smartphone

    Directory of Open Access Journals (Sweden)

    Carlos E. Galván-Tejada

    2015-08-01

    Full Text Available In this paper, we present the development of an infrastructure-less indoor location system (ILS, which relies on the use of a microphone, a magnetometer and a light sensor of a smartphone, all three of which are essentially passive sensors, relying on signals available practically in any building in the world, no matter how developed the region is. In our work, we merge the information from those sensors to estimate the user’s location in an indoor environment. A multivariate model is applied to find the user’s location, and we evaluate the quality of the resulting model in terms of sensitivity and specificity. Our experiments were carried out in an office environment during summer and winter, to take into account changes in light patterns, as well as changes in the Earth’s magnetic field irregularities. The experimental results clearly show the benefits of using the information fusion of multiple sensors when contrasted with the use of a single source of information.

  5. Adaptive speech enhancement using directional microphone in a 4-T MRI scanner.

    Science.gov (United States)

    Sun, Guohua; Li, Mingfeng; Rudd, Brent W; Lim, Teik C; Osterhage, Jeffrey; Fugate, Elizabeth M; Lee, Jing-Huei

    2015-10-01

    To evaluate the effectiveness of the proposed adaptive speech enhancement (ASE) system for the magnetic resonance imaging (MRI) environment to reduce the loud scanning noise without disrupting the communication between patients and MRI operators. The developed system employed the idea of differential directional microphones for measuring and distinguishing the speech signals and MRI acoustic noises simultaneously. Two-stage adaptive filters with normalized least mean square algorithms were adopted. Two common MRI scanning sequences, echo planar imaging (EPI) and gradient echo multi-slice (GEMS), were tested using a 4T MRI scanner. A total of 1.4 and 3.3 dB speech enhancements quantified by the cepstral distance assessment were achieved for the speech signal contaminated with the EPI and GEMS noises, respectively. The speech signal was noticeably recovered, and a clear speech waveform was observed after treated with the ASE system. Furthermore, a non-adaptive post-processing approach [i.e. simply using spectral subtraction (SS) technique] was also adopted to process the abovementioned results. Additional reductions were achieved for the non-coherent MRI acoustic noises. The results showed that combining the proposed ASE system along with the SS approach has a great potential for treating MRI acoustic noise to guarantee an effective communication from patient to MRI operators.

  6. System identification of velocity mechanomyogram measured with a capacitor microphone for muscle stiffness estimation.

    Science.gov (United States)

    Uchiyama, Takanori; Tomoshige, Taiki

    2017-04-01

    A mechanomyogram (MMG) measured with a displacement sensor (displacement MMG) can provide a better estimation of longitudinal muscle stiffness than that measured with an acceleration sensor (acceleration MMG), but the displacement MMG cannot provide transverse muscle stiffness. We propose a method to estimate both longitudinal and transverse muscle stiffness from a velocity MMG using a system identification technique. The aims of this study are to show the advantages of the proposed method. The velocity MMG was measured using a capacitor microphone and a differential circuit, and the MMG, evoked by electrical stimulation, of the tibialis anterior muscle was measured five times in seven healthy young male volunteers. The evoked MMG system was identified using the singular value decomposition method and was approximated with a fourth-order model, which provides two undamped natural frequencies corresponding to the longitudinal and transverse muscle stiffness. The fluctuation of the undamped natural frequencies estimated from the velocity MMG was significantly smaller than that from the acceleration MMG. There was no significant difference between the fluctuations of the undamped natural frequencies estimated from the velocity MMG and that from the displacement MMG. The proposed method using the velocity MMG is thus more advantageous for muscle stiffness estimation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. SoundCompass: A Distributed MEMS Microphone Array-Based Sensor for Sound Source Localization

    Directory of Open Access Journals (Sweden)

    Jelmer Tiete

    2014-01-01

    Full Text Available Sound source localization is a well-researched subject with applications ranging from localizing sniper fire in urban battlefields to cataloging wildlife in rural areas. One critical application is the localization of noise pollution sources in urban environments, due to an increasing body of evidence linking noise pollution to adverse effects on human health. Current noise mapping techniques often fail to accurately identify noise pollution sources, because they rely on the interpolation of a limited number of scattered sound sensors. Aiming to produce accurate noise pollution maps, we developed the SoundCompass, a low-cost sound sensor capable of measuring local noise levels and sound field directionality. Our first prototype is composed of a sensor array of 52 Microelectromechanical systems (MEMS microphones, an inertial measuring unit and a low-power field-programmable gate array (FPGA. This article presents the SoundCompass’s hardware and firmware design together with a data fusion technique that exploits the sensing capabilities of the SoundCompass in a wireless sensor network to localize noise pollution sources. Live tests produced a sound source localization accuracy of a few centimeters in a 25-m2 anechoic chamber, while simulation results accurately located up to five broadband sound sources in a 10,000-m2 open field.

  8. Simultaneous Blind Separation and Recognition of Speech Mixtures Using Two Microphones to Control a Robot Cleaner

    Directory of Open Access Journals (Sweden)

    Heungkyu Lee

    2013-02-01

    Full Text Available This paper proposes a method for the simultaneous separation and recognition of speech mixtures in noisy environments using two-channel based independent vector analysis (IVA on a home-robot cleaner. The issues to be considered in our target application are speech recognition at a distance and noise removal to cope with a variety of noises, including TV sounds, air conditioners, babble, and so on, that can occur in a house, where people can utter a voice command to control a robot cleaner at any time and at any location, even while a robot cleaner is moving. Thus, the system should always be in a recognition-ready state to promptly recognize a spoken word at any time, and the false acceptance rate should be lower. To cope with these issues, the keyword spotting technique is applied. In addition, a microphone alignment method and a model-based real-time IVA approach are proposed to effectively and simultaneously process the speech and noise sources, as well as to cover 360-degree directions irrespective of distance. From the experimental evaluations, we show that the proposed method is robust in terms of speech recognition accuracy, even when the speaker location is unfixed and changes all the time. In addition, the proposed method shows good performance in severely noisy environments.

  9. Compressing Sensing Based Source Localization for Controlled Acoustic Signals Using Distributed Microphone Arrays

    Directory of Open Access Journals (Sweden)

    Wei Ke

    2017-01-01

    Full Text Available In order to enhance the accuracy of sound source localization in noisy and reverberant environments, this paper proposes an adaptive sound source localization method based on distributed microphone arrays. Since sound sources lie at a few points in the discrete spatial domain, our method can exploit this inherent sparsity to convert the localization problem into a sparse recovery problem based on the compressive sensing (CS theory. In this method, a two-step discrete cosine transform- (DCT- based feature extraction approach is utilized to cover both short-time and long-time properties of acoustic signals and reduce the dimensions of the sparse model. In addition, an online dictionary learning (DL method is used to adjust the dictionary for matching the changes of audio signals, and then the sparse solution could better represent location estimations. Moreover, we propose an improved block-sparse reconstruction algorithm using approximate l0 norm minimization to enhance reconstruction performance for sparse signals in low signal-noise ratio (SNR conditions. The effectiveness of the proposed scheme is demonstrated by simulation results and experimental results where substantial improvement for localization performance can be obtained in the noisy and reverberant conditions.

  10. SoundCompass: A Distributed MEMS Microphone Array-Based Sensor for Sound Source Localization

    Science.gov (United States)

    Tiete, Jelmer; Domínguez, Federico; da Silva, Bruno; Segers, Laurent; Steenhaut, Kris; Touhafi, Abdellah

    2014-01-01

    Sound source localization is a well-researched subject with applications ranging from localizing sniper fire in urban battlefields to cataloging wildlife in rural areas. One critical application is the localization of noise pollution sources in urban environments, due to an increasing body of evidence linking noise pollution to adverse effects on human health. Current noise mapping techniques often fail to accurately identify noise pollution sources, because they rely on the interpolation of a limited number of scattered sound sensors. Aiming to produce accurate noise pollution maps, we developed the SoundCompass, a low-cost sound sensor capable of measuring local noise levels and sound field directionality. Our first prototype is composed of a sensor array of 52 Microelectromechanical systems (MEMS) microphones, an inertial measuring unit and a low-power field-programmable gate array (FPGA). This article presents the SoundCompass’s hardware and firmware design together with a data fusion technique that exploits the sensing capabilities of the SoundCompass in a wireless sensor network to localize noise pollution sources. Live tests produced a sound source localization accuracy of a few centimeters in a 25-m2 anechoic chamber, while simulation results accurately located up to five broadband sound sources in a 10,000-m2 open field. PMID:24463431

  11. Fiber-optical microphones and accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

    2010-01-01

    Polymer optical fibers (POFs) are ideal for applications as the sensing element in fiber-optical microphones and accelerometers based on fiber Bragg gratings (FBGs) due to their reduced Young’s Modulus of 3.2GPa, compared to 72GPa of Silica. To maximize the sensitivity and the dynamic range...... of the device the outer diameter and the length of the sensing fiber segment should be as small as possible. To this end we have fabricated 3mm FBGs in single-mode step-index POFs of diameter 115 micron, using 325nm UV writing and a phase-mask technique. 6mm POF sections with FBGs in the center have been glued...... to standard Silica SMF28 fibers. These POF FBGs have been characterized in terms of temperature and strain to find operating regimes with no hysteresis. Commercial fast wavelength interrogators (KHz) are shown to be able to track the thin POF FBGs and they are finally applied in a prototype accelerometer...

  12. Connections between quantum chromodynamics and condensed ...

    Indian Academy of Sciences (India)

    Abstract. Features of QCD can be seen qualitatively in certain condensed matter systems. Recently some of the analyses that originated in condensed matter physics have found applications in QCD. Using examples we discuss some of the connections between the two fields and show how progress can be made by ...

  13. Condensate growth in trapped Bose gates

    NARCIS (Netherlands)

    Bijlsma, M.J.; Zaremba, E.; Stoof, H.T.C.

    2000-01-01

    We study the dynamics of condensate fromation in an inhomogeneous trapped Bose gas with a positive interatomic scattering length. We take into account both the nonequilibrium kinetics of the thermal cloud and the Hartree-Fock mean-field efects in the condensed and the noncondensed parts of the gas.

  14. Condensate growth in trapped Bose gases

    NARCIS (Netherlands)

    Bijlsma, M.J.; Zaremba, E.; Stoof, H.T.C.

    2000-01-01

    We study the dynamics of condensate formation in an inhomogeneous trapped Bose gas with a positive interatomic scattering length. We take into account both the nonequilibrium kinetics of the thermal cloud and the Hartree-Fock mean-field effects in the condensed and the noncondensed parts of the gas.

  15. Tunneling of trapped-atom Bose condensates

    Indian Academy of Sciences (India)

    Tunneling of trapped-atom Bose condensates. SUBODH R SHENOY. Abdus Salam International Centre for Theoretical Physics, P.O. Box 586, Trieste 34100, Italy. Abstract. We obtain the dynamics in number and phase difference, for Bose condensates that tun- nel between two wells of a double-well atomic trap, using the ...

  16. Collision of Bose Condensate Dark Matter structures

    International Nuclear Information System (INIS)

    Guzman, F. S.

    2008-01-01

    The status of the scalar field or Bose condensate dark matter model is presented. Results about the solitonic behavior in collision of structures is presented as a possible explanation to the recent-possibly-solitonic behavior in the bullet cluster merger. Some estimates about the possibility to simulate the bullet cluster under the Bose Condensate dark matter model are indicated.

  17. Soliton resonance in bose-einstein condensate

    Science.gov (United States)

    Zak, Michail; Kulikov, I.

    2002-01-01

    A new phenomenon in nonlinear dispersive systems, including a Bose-Einstein Condensate (BEC), has been described. It is based upon a resonance between an externally induced soliton and 'eigen-solitons' of the homogeneous cubic Schrodinger equation. There have been shown that a moving source of positive /negative potential induces bright /dark solitons in an attractive / repulsive Bose condensate.

  18. Effective thermal conductivity of condensed polymeric nanofluids ...

    Indian Academy of Sciences (India)

    Thermal properties of polymeric nanosolids, obtained by condensing the corresponding nanofluids, are investigated using photothermal techniques. The heat transport properties of two sets of polyvinyl alcohol (PVA) based nanosolids, TiO2/PVA and Cu/PVA, prepared by condensing the respective nanofluids, which are ...

  19. Quantum monodromy in trapped Bose condensates

    NARCIS (Netherlands)

    Waalkens, H.

    2002-01-01

    Bose-Einstein condensation of ultra cold atoms is typically realized in magnetic traps which effectively lead to an axially symmetric harmonic potential. This letter shows that the spectrum of collective vibrational modes of a repulsive condensate in a prolate potential displays a defect known as

  20. Born-Kothari Condensation for Fermions

    Directory of Open Access Journals (Sweden)

    Arnab Ghosh

    2017-09-01

    Full Text Available In the spirit of Bose–Einstein condensation, we present a detailed account of the statistical description of the condensation phenomena for a Fermi–Dirac gas following the works of Born and Kothari. For bosons, while the condensed phase below a certain critical temperature, permits macroscopic occupation at the lowest energy single particle state, for fermions, due to Pauli exclusion principle, the condensed phase occurs only in the form of a single occupancy dense modes at the highest energy state. In spite of these rudimentary differences, our recent findings [Ghosh and Ray, 2017] identify the foregoing phenomenon as condensation-like coherence among fermions in an analogous way to Bose–Einstein condensate which is collectively described by a coherent matter wave. To reach the above conclusion, we employ the close relationship between the statistical methods of bosonic and fermionic fields pioneered by Cahill and Glauber. In addition to our previous results, we described in this mini-review that the highest momentum (energy for individual fermions, prerequisite for the condensation process, can be specified in terms of the natural length and energy scales of the problem. The existence of such condensed phases, which are of obvious significance in the context of elementary particles, have also been scrutinized.

  1. Dropwise Condensation Enhancement on Geometric Features

    Science.gov (United States)

    Zhao, Yajing; Preston, Daniel J.; Lu, Zhengmao; Wang, Evelyn N.

    Dropwise condensation, which has been demonstrated to exhibit a 5-7X higher heat transfer coefficient compared with state-of-the-art filmwise condensation, contributes to energy savings in a wide range of applications such as desalination systems, steam cycles and dew harvesting. In order to enhance dropwise condensation performance, previous studies have investigated the effects of surface geometric features on droplet growth rates and found that bumps protruding from surfaces can effectively promote dropwise condensation. In this work, we show that while bumps on surfaces enable droplets to grow faster in some cases, there are also cases where bumps on surfaces actually degrade dropwise condensation. We numerically simulated and experimentally demonstrated that even the same surface geometric feature can exert completely opposite effects on dropwise condensation of water under two different working conditions (pure vapor vs. air vapor mixture). This phenomenon is explained by comparing the heat and mass transfer resistance of the surface structure to that of the vapor transport during dropwise condensation. We expect that the fundamental understanding developed in this study will provide useful guidelines for relevant condensation applications.

  2. Assessment of the controllability of condensible emissions. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Shareef, G.S.; Waddell, J.T.

    1990-10-01

    The report gives results of a study to gain insights into the condensible emissions area from an air toxics perspective, with emphasis on controllability and chemical composition of these emissions. The study: compiled existing data on condensible emissions; determined the chemical composition of condensible emissions, where possible; identified source categories that are major emitters of condensibles; evaluated the effectiveness of various control devices in reducing condensible emissions; and evaluated how the performance of currently available control technologies can be improved to better control condensible emissions. Two data bases were developed: the Condensibles Data Base contains 43 emission source categories; the Specialized Condensibles Data Base focuses on the chemical composition of condensible emissions.

  3. Capillary Condensation in 8 nm Deep Channels.

    Science.gov (United States)

    Zhong, Junjie; Riordon, Jason; Zandavi, Seyed Hadi; Xu, Yi; Persad, Aaron H; Mostowfi, Farshid; Sinton, David

    2018-02-01

    Condensation on the nanoscale is essential to understand many natural and synthetic systems relevant to water, air, and energy. Despite its importance, the underlying physics of condensation initiation and propagation remain largely unknown at sub-10 nm, mainly due to the challenges of controlling and probing such small systems. Here we study the condensation of n-propane down to 8 nm confinement in a nanofluidic system, distinct from previous studies at ∼100 nm. The condensation initiates significantly earlier in the 8 nm channels, and it initiates from the entrance, in contrast to channels just 10 times larger. The condensate propagation is observed to be governed by two liquid-vapor interfaces with an interplay between film and bridging effects. We model the experimental results using classical theories and find good agreement, demonstrating that this 8 nm nonpolar fluid system can be treated as a continuum from a thermodynamic perspective, despite having only 10-20 molecular layers.

  4. Condensing boiler applications in the process industry

    International Nuclear Information System (INIS)

    Chen, Qun; Finney, Karen; Li, Hanning; Zhang, Xiaohui; Zhou, Jue; Sharifi, Vida; Swithenbank, Jim

    2012-01-01

    Major challenging issues such as climate change, energy prices and fuel security have focussed the attention of process industries on their energy efficiency and opportunities for improvement. The main objective of this research study was to investigate technologies needed to exploit the large amount of low grade heat available from a flue gas condensing system through industrial condensing boilers. The technology and application of industrial condensing boilers in various heating systems were extensively reviewed. As the condensers require site-specific engineering design, a case study was carried out to investigate the feasibility (technically and economically) of applying condensing boilers in a large scale district heating system (40 MW). The study showed that by recovering the latent heat of water vapour in the flue gas through condensing boilers, the whole heating system could achieve significantly higher efficiency levels than conventional boilers. In addition to waste heat recovery, condensing boilers can also be optimised for emission abatement, especially for particle removal. Two technical barriers for the condensing boiler application are corrosion and return water temperatures. Highly corrosion-resistant material is required for condensing boiler manufacture. The thermal design of a 'case study' single pass shell-and-tube condensing heat exchanger/condenser showed that a considerable amount of thermal resistance was on the shell-side. Based on the case study calculations, approximately 4900 m 2 of total heat transfer area was required, if stainless steel was used as a construction material. If the heat transfer area was made of carbon steel, then polypropylene could be used as the corrosion-resistant coating material outside the tubes. The addition of polypropylene coating increased the tube wall thermal resistance, hence the required heat transfer area was approximately 5800 m 2 . Net Present Value (NPV) calculations showed that the choice of a carbon

  5. Condensing embryology teaching: alternative perspectives

    Directory of Open Access Journals (Sweden)

    Hasan M

    2018-03-01

    Full Text Available Mohammad Hasan, Syed Maaz Tariq, Syed Ali Haider Department of MBBS, Jinnah Sindh Medical University, Karachi, PakistanWe read the article “Condensing embryology teaching for medical students: can it be taught in 2 hours?” by Kazzazi and Bartlett quite attentively. The authors were successful in mentioning an effective mode of teaching embryology. Embryology is indeed an important subject that forms the base for appreciating anatomy and has immense practical implementations in different parts of medicine, for example, in pediatrics and ENT surgery. However, it is often neglected and is only taught in preclinical years.1 The authors proposed a method for teaching embryology splendidly from their perspective; therefore, we felt the need to expand the discussion from the perspective of third-year medical students who have just completed their preclinical years. Hence, we would like to mention few limitations to this study as well.Authors’ replyFawz Kazzazi, Jonathan Bartlett School of Clinical Medicine, University of Cambridge, Cambridge, UKWe read with interest the response letter by Hasan et al. We must first commend the editor and journal on their great ability to unify the medical community and extend topics for debate internationally.View the original paper by Kazzazi and Bartlett.

  6. Topology and condensed matter physics

    CERN Document Server

    Mj, Mahan; Bandyopadhyay, Abhijit

    2017-01-01

    This book introduces aspects of topology and applications to problems in condensed matter physics. Basic topics in mathematics have been introduced in a form accessible to physicists, and the use of topology in quantum, statistical and solid state physics has been developed with an emphasis on pedagogy. The aim is to bridge the language barrier between physics and mathematics, as well as the different specializations in physics. Pitched at the level of a graduate student of physics, this book does not assume any additional knowledge of mathematics or physics. It is therefore suited for advanced postgraduate students as well. A collection of selected problems will help the reader learn the topics on one's own, and the broad range of topics covered will make the text a valuable resource for practising researchers in the field.  The book consists of two parts: one corresponds to developing the necessary mathematics and the other discusses applications to physical problems. The section on mathematics is a qui...

  7. Ice-condenser aerosol tests

    International Nuclear Information System (INIS)

    Ligotke, M.W.; Eschbach, E.J.; Winegardner, W.K.

    1991-09-01

    This report presents the results of an experimental investigation of aerosol particle transport and capture using a full-scale height and reduced-scale cross section test facility based on the design of the ice compartment of a pressurized water reactor (PWR) ice-condenser containment system. Results of 38 tests included thermal-hydraulic as well as aerosol particle data. Particle retention in the test section was greatly influenced by thermal-hydraulic and aerosol test parameters. Test-average decontamination factor (DF) ranged between 1.0 and 36 (retentions between ∼0 and 97.2%). The measured test-average particle retentions for tests without and with ice and steam ranged between DF = 1.0 and 2.2 and DF = 2.4 and 36, respectively. In order to apparent importance, parameters that caused particle retention in the test section in the presence of ice were steam mole fraction (SMF), noncondensible gas flow rate (residence time), particle solubility, and inlet particle size. Ice-basket section noncondensible flows greater than 0.1 m 3 /s resulted in stable thermal stratification whereas flows less than 0.1 m 3 /s resulted in thermal behavior termed meandering with frequent temperature crossovers between flow channels. 10 refs., 66 figs., 16 tabs

  8. Ice-condenser aerosol tests

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.; Eschbach, E.J.; Winegardner, W.K. (Pacific Northwest Lab., Richland, WA (United States))

    1991-09-01

    This report presents the results of an experimental investigation of aerosol particle transport and capture using a full-scale height and reduced-scale cross section test facility based on the design of the ice compartment of a pressurized water reactor (PWR) ice-condenser containment system. Results of 38 tests included thermal-hydraulic as well as aerosol particle data. Particle retention in the test section was greatly influenced by thermal-hydraulic and aerosol test parameters. Test-average decontamination factor (DF) ranged between 1.0 and 36 (retentions between {approximately}0 and 97.2%). The measured test-average particle retentions for tests without and with ice and steam ranged between DF = 1.0 and 2.2 and DF = 2.4 and 36, respectively. In order to apparent importance, parameters that caused particle retention in the test section in the presence of ice were steam mole fraction (SMF), noncondensible gas flow rate (residence time), particle solubility, and inlet particle size. Ice-basket section noncondensible flows greater than 0.1 m{sup 3}/s resulted in stable thermal stratification whereas flows less than 0.1 m{sup 3}/s resulted in thermal behavior termed meandering with frequent temperature crossovers between flow channels. 10 refs., 66 figs., 16 tabs.

  9. Data Acquisition and Digital Filtering for Infrasonic Records on Active Volcanoes

    Directory of Open Access Journals (Sweden)

    José Chilo

    2007-03-01

    Full Text Available This paper presents the design of a digital data acquisition system for volcanic infrasound records. The system includes four electret condenser element microphones, a QF4A512 programmable signal converter from Quickfilter Technologies and a MSP430 microcontroller from Texas Instruments. The signal output of every microphone is converted to digital via a 16-bit Analog to Digital Converter (ADC. To prevent errors in the conversion process, Anti-Aliasing Filters are employed prior to the ADC. Digital filtering is performed after the ADC using a Digital Signal Processor, which is implemented on the QF4A512. The four digital signals are summed to get only one signal. Data storing and digital wireless data transmission will be described in a future paper.

  10. Direct contact condensation in packed beds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi; Klausner, James F.; Mei, Renwei; Knight, Jessica [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2006-12-15

    A diffusion driven desalination process was recently described where a very effective direct contact condenser with a packed bed is used to condense water vapor out of an air/vapor mixture. A laboratory scale direct contact condenser has been fabricated as a twin tower structure with two stages, co-current and countercurrent. Experiments have been operated in each stage with respective saturated air inlet temperatures of 36, 40 and 43{sup o}C. The temperature and humidity data have been collected at the inlet and exit of the packed bed for different water to air mass flow ratios that vary between 0 and 2.5. A one-dimensional model based on conservation principles has been developed, which predicts the variation of temperature, humidity, and condensation rate through the condenser stages. Agreement between the model and experiments is very good. It is observed that the countercurrent flow stage condensation effectiveness is significantly higher than that for the co-current stage. The condensation heat and mass transfer rates were found to decrease when water blockages occur within the packed bed. Using high-speed digital cinematography, it was observed that this problem can occur at any operating condition, and is dependent on the packing surface wetting characteristics. This observation is used to explain the requirement for two different empirical constants, depending on packing diameter, suggested by Onda for the air side mass transfer coefficient correlation. (author)

  11. Emergency condensator for BWR type reactor

    International Nuclear Information System (INIS)

    Ubakai, Yoichi; Narumi, Yuichi; Sakata, Yuji.

    1992-01-01

    An emergency condensator is constituted with heat transfer pipes, a steam chamber, an upper pipe plate, a lower pipe plate and a condensate chamber. The upper pipe plate is secured by supports, and a steam pipe is connected to the upper pipe plate. A condensate pipeline and a incondensible gas vent pipe are disposed to the condensate chamber. Taking thermal expansion of the steam pipes and thermal expansion of the heat transfer pipes into consideration, the heat transfer pipe is made as an L-shaped pipe having a vertical portion and a horizontal portion so as to absorb each of the thermal expansion smoothly. The L-shaped heat transfer pipes are constituted as a bundle of pipes having the end portions thereof secured to the upper pipe plate and the lower pipe plate. The emergency condensator is disposed in a emergency condensator pool chamber. Cooling water in contact with the outer side of the L-shaped heat transfer pipes is the pool water in the pool chamber, and the condensator chamber is disposed in concrete walls of the pool chamber. With such a constitution, stress due to thermal expansion of the heat transfer pipes is mitigated, and heat transfer performance, earth quake resistance and maintenancability are improved. (I.N.)

  12. Low-temperature Condensation of Carbon

    Science.gov (United States)

    Krasnokutski, S. A.; Goulart, M.; Gordon, E. B.; Ritsch, A.; Jäger, C.; Rastogi, M.; Salvenmoser, W.; Henning, Th.; Scheier, P.

    2017-10-01

    Two different types of experiments were performed. In the first experiment, we studied the low-temperature condensation of vaporized graphite inside bulk liquid helium, while in the second experiment, we studied the condensation of single carbon atoms together with H2, H2O, and CO molecules inside helium nanodroplets. The condensation of vaporized graphite leads to the formation of partially graphitized carbon, which indicates high temperatures, supposedly higher than 1000°C, during condensation. Possible underlying processes responsible for the instant rise in temperature during condensation are discussed. This suggests that such processes cause the presence of partially graphitized carbon dust formed by low-temperature condensation in the diffuse interstellar medium. Alternatively, in the denser regions of the ISM, the condensation of carbon atoms together with the most abundant interstellar molecules (H2, H2O, and CO), leads to the formation of complex organic molecules (COMs) and finally organic polymers. Water molecules were found not to be involved directly in the reaction network leading to the formation of COMs. It was proposed that COMs are formed via the addition of carbon atoms to H2 and CO molecules ({{C}}+{{{H}}}2\\to {HCH},{HCH}+{CO}\\to {{OCCH}}2). Due to the involvement of molecular hydrogen, the formation of COMs by carbon addition reactions should be more efficient at high extinctions compared with the previously proposed reaction scheme with atomic hydrogen.

  13. The group delay and suppression pattern of the cochlear microphonic potential recorded at the round window.

    Directory of Open Access Journals (Sweden)

    Wenxuan He

    Full Text Available BACKGROUND: It is commonly assumed that the cochlear microphonic potential (CM recorded from the round window (RW is generated at the cochlear base. Based on this assumption, the low-frequency RW CM has been measured for evaluating the integrity of mechanoelectrical transduction of outer hair cells at the cochlear base and for studying sound propagation inside the cochlea. However, the group delay and the origin of the low-frequency RW CM have not been demonstrated experimentally. METHODOLOGY/PRINCIPAL FINDINGS: This study quantified the intra-cochlear group delay of the RW CM by measuring RW CM and vibrations at the stapes and basilar membrane in gerbils. At low sound levels, the RW CM showed a significant group delay and a nonlinear growth at frequencies below 2 kHz. However, at high sound levels or at frequencies above 2 kHz, the RW CM magnitude increased proportionally with sound pressure, and the CM phase in respect to the stapes showed no significant group delay. After the local application of tetrodotoxin the RW CM below 2 kHz became linear and showed a negligible group delay. In contrast to RW CM phase, the BM vibration measured at location ∼2.5 mm from the base showed high sensitivity, sharp tuning, and nonlinearity with a frequency-dependent group delay. At low or intermediate sound levels, low-frequency RW CMs were suppressed by an additional tone near the probe-tone frequency while, at high sound levels, they were partially suppressed only at high frequencies. CONCLUSIONS/SIGNIFICANCE: We conclude that the group delay of the RW CM provides no temporal information on the wave propagation inside the cochlea, and that significant group delay of low-frequency CMs results from the auditory nerve neurophonic potential. Suppression data demonstrate that the generation site of the low-frequency RW CM shifts from apex to base as the probe-tone level increases.

  14. Active condensation of water by plants

    Directory of Open Access Journals (Sweden)

    Prokhorov Alexey Anatolievich

    2013-10-01

    Full Text Available This paper is devoted to some peculiarities of water condensation on the surface of plants . Arguments in support of the hypothesis that in decreasing temperature of leaves and shoots below the dew point, the plant can actively condense moisture from the air, increasing the duration of dewfall are presented. Evening dewfall on plant surfaces begins before starting the formation of fog. Morning condensation continues for some time after the air temperature exceeds the dew point . The phenomenon in question is found everywhere, but it is particularly important for plants in arid ecosystems.

  15. Quark virtuality and QCD vacuum condensates

    International Nuclear Information System (INIS)

    Zhou Lijuan; Ma Weixing

    2004-01-01

    Based on the Dyson-Schwinger equations (DSEs) in the 'rainbow' approximation, the authors investigate the quark virtuality in the vacuum state and quantum-chromodynamics (QCD) vacuum condensates. In particular, authors calculate the local quark vacuum condensate and quark-gluon mixed condensates, and then the virtuality of quark. The calculated quark virtualities are λ u,d 2 =0.7 GeV 2 for u, d quarks, and λ s 2 =1.6 GeV 2 for s quark. The theoretical predictions are consistent with empirical values used in QCD sum rules, and also fit to lattice QCD predictions

  16. Open string decoupling and tachyon condensation

    International Nuclear Information System (INIS)

    Chalmers, G.

    2001-01-01

    The amplitudes in perturbative open string theory are examined as functions of the tachyon condensate parameter. The boundary state formalism demonstrates the decoupling of the open string modes at the non-perturbative minima of the tachyon potential via a degeneration of open world-sheets and identifies an independence of the coupling constants g s and g YM at general values of the tachyon condensate. The closed sector is generated at the quantum level; it is also generated at the classical level through the condensation of the propagating open string modes on the D-brane degrees of freedom.

  17. Preoperational test report, primary ventilation condensate system

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, F.T.

    1997-01-29

    Preoperational test report for Primary Ventilation Condensate System, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides a collection point for condensate generated by the W-030 primary vent offgas cooling system serving tanks AYIOI, AY102, AZIOI, AZI02. The system is located inside a shielded ventilation equipment cell and consists of a condensate seal pot, sampling features, a drain line to existing Catch Tank 241-AZ-151, and a cell sump jet pump. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  18. The Dynamics of Aerosols in Condensational Scrubbers

    DEFF Research Database (Denmark)

    Johannessen, Jens Tue; Christensen, Jan A.; Simonsen, Ole

    1997-01-01

    A mathematical model for the simulation of the dynamics of aerosol change in condensational scrubbers and scrubbing condensers is proposed. The model is applicable for packed column gas/liquid contact when plug flow can be assumed. The model is compared with experimental data for particle removal...... in a pilot plant condensational scrubber. The model can satisfactorily predict particle growth and particle deposition by diffusional, convective and inertial mechanisms for a wide range of conditions. The parameters of principal importance for the model precision are identified and a procedure...

  19. Model of a chromomagnetic condensate in QCD

    International Nuclear Information System (INIS)

    Vladimirsky, V.V.

    1996-01-01

    The simplest form of the effective Lagrangian of a gluon field leads to a deep degeneracy of a magnetic condensate that arises when the stability of the standard perturbative vacuum is violated by quantum effects. The inclusion of terms in the effective Lagrangian that conserve color and Lorentz invariance enables the possible types of Abelian and non-Abelian condensate fields to be classified. The degeneracy is partially removed. One of the four types of the condensate permits the emergence of closed vortex lines that correspond to cyclic permutations of colors upon circumventions around stringlike singularities

  20. Bimodal condensation silicone elastomers as dielectric elastomers

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Skov, Anne Ladegaard

    unimodal refers to that there is one polymer only in the system. As an alternative to unimodal networks there are the bimodal networks where two polymers with significantly different molecular weights are mixed with one crosslinker. [2]Silicone rubber can be divided into condensation type and addition type...... according to the curing reaction. The advantages of condensation silicones compared to addition are the relatively low cost, the curing rate largely being independent of temperature, the excellent adhesion, and the catalyst being nontoxic. [3]In this work, a series of bimodal condensation silicone...

  1. Holography, Gravity and Condensed Matter

    Energy Technology Data Exchange (ETDEWEB)

    Hartnoll, Sean [Stanford Univ., CA (United States). Dept. of Physics

    2017-12-20

    Over the five years of funding from this grant, I produced 26 publications. These include a book-long monograph on "Holographic Quantum Matter" that is currently in press with MIT press. The remainder were mostly published in Physical Review Letters, the Journal of High Energy Physics, Nature Physics, Classical and Quantum Gravity and Physical Review B. Over this period, the field of holography applied to condensed matter physics developed from a promising theoretical approach to a mature conceptual and practical edifice, whose ideas were realized in experiments. My own work played a central role in this development. In particular, in the final year of this grant, I co-authored two experimental papers in which ideas that I had developed in earlier years were shown to usefully describe transport in strongly correlated materials — these papers were published in Science and in the Proceedings of the National Academy of Sciences (obviously my contribution to these papers was theoretical). My theoretical work in this period developed several new directions of research that have proven to be influential. These include (i) The construction of highly inhomogeneous black hole event horizons, realizing disordered fixed points and describing new regimes of classical gravity, (ii) The conjecture of a bound on diffusivities that could underpin transport in strongly interacting media — an idea which may be proven in the near future and has turned out to be intimately connected to studies of quantum chaos in black holes and strongly correlated media, (iii) The characterization of new forms of hydrodynamic transport, e.g. with phase-disordered order parameters. These studies pertain to key open questions in our understanding of how non-quasiparticle, intrinsically strongly interacting systems can behave. In addition to the interface between holography and strongly interacting condensed matter systems, I made several advances on understanding the role of entanglement in quantum

  2. Efficient, Long-Life Biocidal Condenser, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Environmental control systems for manned lunar and planetary bases will require condensing heat exchangers to control humidity. Condensing surfaces must be...

  3. Nautilus Centripetal Capillary Condenser, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A Nautilus Centripetal Capillary Condenser (NCCC) is proposed for the microgravity compatible removal of water from a saturated air stream. Successful development of...

  4. High temperature Bose-Einstein condensation

    Directory of Open Access Journals (Sweden)

    Begun Viktor

    2016-01-01

    Full Text Available The indications of a possible pion condensation at the LHC are summarized. The condensation is predicted by the non-equilibrium hadronization model for 2.76 TeV Pb+Pb collisions at the LHC. The model solves the proton/pion puzzle and reproduces the low pT enhancement of the pion spectra, as well as the spectra of protons and antiprotons, charged kaons, K0S, K*(8920 and ϕ(1020. The obtained parameters allow to estimate the amount of pion condensate on the level of 5% from the total number of pions at the LHC. The condensate is located at pT < 250 MeV.

  5. Kaon condensation in dense stellar matter

    International Nuclear Information System (INIS)

    Lee, Chang-Hwan; Rho, M.; Washington Univ., Seattle, WA

    1995-03-01

    This article combines two talks given by the authors and is based on Works done in collaboration with G.E. Brown and D.P. Min on kaon condensation in dense baryonic medium treated in chiral perturbation theory using heavy-baryon formalism. It contains, in addition to what was recently published, astrophysical backgrounds for kaon condensation discussed by Brown and Bethe, a discussion on a renormalization-group analysis to meson condensation worked out together with H.K. Lee and S.J. Sin, and the recent results of K.M. Westerberg in the bound-state approach to the Skyrme model. Negatively charged kaons are predicted to condense at a critical density 2 approx-lt ρ/ρo approx-lt 4, in the range to allow the intriguing new phenomena predicted by Brown and Bethe to take place in compact star matter

  6. Fundamentals of evaporation and condensation phenomena

    International Nuclear Information System (INIS)

    Munir, Z.A.

    1979-01-01

    Fundamental relationships governing evaporation and condensation processes are reviewed. The terrace-ledge-kink (TLK) model is discussed in terms of atomic steps comprising growth and evaporation of crystals. Recent results in the field are described

  7. Accretion of Ghost Condensate by Black Holes

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, A

    2004-06-02

    The intent of this letter is to point out that the accretion of a ghost condensate by black holes could be extremely efficient. We analyze steady-state spherically symmetric flows of the ghost fluid in the gravitational field of a Schwarzschild black hole and calculate the accretion rate. Unlike minimally coupled scalar field or quintessence, the accretion rate is set not by the cosmological energy density of the field, but by the energy scale of the ghost condensate theory. If hydrodynamical flow is established, it could be as high as tenth of a solar mass per second for 10MeV-scale ghost condensate accreting onto a stellar-sized black hole, which puts serious constraints on the parameters of the ghost condensate model.

  8. Recent developments in Bose-Einstein condensation

    Energy Technology Data Exchange (ETDEWEB)

    Kalman, G.

    1997-09-22

    This paper contains viewgraphs on developments on Bose-Einstein condensation. Some topics covered are: strongly coupled coulomb systems; standard response functions of the first and second kind; dynamical mean field theory; quasi localized charge approximation; and the main equations.

  9. Extending bioacoustic monitoring of birds aloft through flight call localization with a three-dimensional microphone array.

    Science.gov (United States)

    Stepanian, Phillip M; Horton, Kyle G; Hille, David C; Wainwright, Charlotte E; Chilson, Phillip B; Kelly, Jeffrey F

    2016-10-01

    Bioacoustic localization of bird vocalizations provides unattended observations of the location of calling individuals in many field applications. While this technique has been successful in monitoring terrestrial distributions of calling birds, no published study has applied these methods to migrating birds in flight. The value of nocturnal flight call recordings can increase with the addition of three-dimensional position retrievals, which can be achieved with adjustments to existing localization techniques. Using the time difference of arrival method, we have developed a proof-of-concept acoustic microphone array that allows the three-dimensional positioning of calls within the airspace. Our array consists of six microphones, mounted in pairs at the top and bottom of three 10-m poles, arranged in an equilateral triangle with sides of 20 m. The microphone array was designed using readily available components and costs less than $2,000 USD to build and deploy. We validate this technique using a kite-lofted GPS and speaker package, and obtain 60.1% of vertical retrievals within the accuracy of the GPS measurements (±5 m) and 80.4% of vertical retrievals within ±10 m. The mean Euclidian distance between the acoustic retrievals of flight calls and the GPS truth was 9.6 m. Identification and localization of nocturnal flight calls have the potential to provide species-specific spatial characterizations of bird migration within the airspace. Even with the inexpensive equipment used in this trial, low-altitude applications such as surveillance around wind farms or oil platforms can benefit from the three-dimensional retrievals provided by this technique.

  10. Conditions for maximum isolation of stable condensate during separation in gas-condensate systems

    Energy Technology Data Exchange (ETDEWEB)

    Trivus, N.A.; Belkina, N.A.

    1969-02-01

    A thermodynamic analysis is made of the gas-liquid separation process in order to determine the relationship between conditions of maximum stable condensate separation and physico-chemical nature and composition of condensate. The analysis was made by considering the multicomponent gas-condensate fluid produced from Zyrya field as a ternary system, composed of methane, an intermediate component (propane and butane) and a heavy residue, C/sub 6+/. Composition of 5 ternary systems was calculated for a wide variation in separator conditions. At each separator pressure there is maximum condensate production at a certain temperature. This occurs because solubility of condensate components changes with temperature. Results of all calculations are shown graphically. The graphs show conditions of maximum stable condensate separation.

  11. Stabilization flyuorytopodibnoyi structure in oxide vacuum condensate

    Directory of Open Access Journals (Sweden)

    О.М. Заславський

    2006-01-01

    Full Text Available  The influence of the oxide-stabilizer content, M'-cation radius and film deposition temperature on the stabilization of the fluorite-like solid solutions in the zirconium and hafnium oxides-based vacuum condensates, obtained by Laser-evaporating method, was investigated. The optimum parameters of the coatication of the isotropic thermostable coverings was determined. This results were explained by using of the high-speed condensation in vacuum theory.

  12. Gauge independence of the Ao-condensate

    International Nuclear Information System (INIS)

    Skalozub, V.V.

    1992-01-01

    The problem of gauge dependence of the zero gauge field component condensate. A o =const, in the framework of finite temperature SU(2) gluodynamics is investigated. In straight-forward calculations it is shown that the two-loop effective action W(A o ,ζ) satisfies the generalized Nielsen identity. Thus, the gauge invariance of the A o -condensation is proved. 12 refs. (author)

  13. Condenser cooling water quality at Kaiga

    International Nuclear Information System (INIS)

    Namboodiri, E.G.A.

    1995-01-01

    Once-through circulation of river water is envisaged in Kaiga for cooling the condenser and other related equipment. Water drawn from Kali river will be used for this purpose. After cooling the condenser, the water is let into the river through the outfall system. The materials used in the cooling water system consist mainly of SS 316 and carbon steel. Chlorination is the treatment proposed to the cooling water. The cooling water quality is found to be satisfactory. (author). 2 refs

  14. Condensate of massive graviton and dark matter

    OpenAIRE

    Aoki, Katsuki; Maeda, Kei-ichi

    2018-01-01

    We study coherently oscillating massive gravitons in the ghost-free bigravity theory. This coherent field can be interpreted as a condensate of the massive gravitons. We first define the effective energy-momentum tensor of the coherent massive gravitons in a curved spacetime. We then study the background dynamics of the universe and the cosmic structure formation including the effects of the coherent massive gravitons. We find that the condensate of the massive graviton behaves as a dark matt...

  15. Vector condensate model of electroweak interactions

    International Nuclear Information System (INIS)

    Cynolter, G.; Pocsik, G.

    1997-01-01

    Motivated by the fact that the Higgs is not seen, a new version of the standard model is proposed where the scalar doublet is replaced by a vector doublet and its neutral member forms a nonvanishing condensate. Gauge fields are coupled to the new vector fields B in a gauge invariant way leading to mass terms for the gauge fields by condensation. The model is presented and some implications are discussed. (K.A.)

  16. Fermion condensation and gapped domain walls in topological orders

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Yidun [Department of Physics and Center for Field Theory and Particle Physics, Fudan University,Shanghai 200433 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University,Nanjing 210093 (China); Perimeter Institute for Theoretical Physics,Waterloo N2L 2Y5, Ontario (Canada); Wang, Chenjie [Perimeter Institute for Theoretical Physics,Waterloo N2L 2Y5, Ontario (Canada)

    2017-03-31

    We study fermion condensation in bosonic topological orders in two spatial dimensions. Fermion condensation may be realized as gapped domain walls between bosonic and fermionic topological orders, which may be thought of as real-space phase transitions from bosonic to fermionic topological orders. This picture generalizes the previous idea of understanding boson condensation as gapped domain walls between bosonic topological orders. While simple-current fermion condensation was considered before, we systematically study general fermion condensation and show that it obeys a Hierarchy Principle: a general fermion condensation can always be decomposed into a boson condensation followed by a minimal fermion condensation. The latter involves only a single self-fermion that is its own anti-particle and that has unit quantum dimension. We develop the rules of minimal fermion condensation, which together with the known rules of boson condensation, provides a full set of rules for general fermion condensation.

  17. Analysis of Adaptive Feedback and Echo Cancelation Algorithms in A General Multiple-Microphone and Single-Loudspeaker System

    DEFF Research Database (Denmark)

    Guo, Meng; Elmedyb, Thomas Bo; Jensen, Søren Holdt

    2011-01-01

    In this paper, we analyze a general multiple-microphone and single-loudspeaker system, where an adaptive algorithm is used to cancel acoustic feedback/echo and a beamformer processes the feedback/echo canceled signals. This system can be viewed as part of a typical hearing aid system and....../or a traditional acoustic echo cancelation system. We introduce and derive an approximation of a useful frequency domain measure - the power transfer function - and show how to predict the system stability bound, convergence rate and the steady-state behavior across time and frequency. Furthermore, we show how...

  18. The Effects of Hearing Aid Directional Microphone and Noise Reduction Processing on Listening Effort in Older Adults with Hearing Loss.

    Science.gov (United States)

    Desjardins, Jamie L

    2016-01-01

    Older listeners with hearing loss may exert more cognitive resources to maintain a level of listening performance similar to that of younger listeners with normal hearing. Unfortunately, this increase in cognitive load, which is often conceptualized as increased listening effort, may come at the cost of cognitive processing resources that might otherwise be available for other tasks. The purpose of this study was to evaluate the independent and combined effects of a hearing aid directional microphone and a noise reduction (NR) algorithm on reducing the listening effort older listeners with hearing loss expend on a speech-in-noise task. Participants were fitted with study worn commercially available behind-the-ear hearing aids. Listening effort on a sentence recognition in noise task was measured using an objective auditory-visual dual-task paradigm. The primary task required participants to repeat sentences presented in quiet and in a four-talker babble. The secondary task was a digital visual pursuit rotor-tracking test, for which participants were instructed to use a computer mouse to track a moving target around an ellipse that was displayed on a computer screen. Each of the two tasks was presented separately and concurrently at a fixed overall speech recognition performance level of 50% correct with and without the directional microphone and/or the NR algorithm activated in the hearing aids. In addition, participants reported how effortful it was to listen to the sentences in quiet and in background noise in the different hearing aid listening conditions. Fifteen older listeners with mild sloping to severe sensorineural hearing loss participated in this study. Listening effort in background noise was significantly reduced with the directional microphones activated in the hearing aids. However, there was no significant change in listening effort with the hearing aid NR algorithm compared to no noise processing. Correlation analysis between objective and self

  19. Improvement of the estimate of the speaker-error microphone transfer function in an active noise controller

    Science.gov (United States)

    Minguez, Antonio; Recuero, M.

    A new method is proposed to improve the estimate of the transfer function between the loudspeaker and the error microphone (H(z)) with the help of an auxiliary white noise. This method made the plant acoustic noise level independent from the auxiliary random noise, and thus, the amplitude of this noise can be reduced improving the total system performance. The idea is to remove the acoustic noise from the error signal with adaptive schemes, thus, the plant acoustic noise will not affect the convergence of the LMS FIR algorithm used in a direct scheme of identification of H(z).

  20. Sound Source Localization through 8 MEMS Microphones Array Using a Sand-Scorpion-Inspired Spiking Neural Network.

    Science.gov (United States)

    Beck, Christoph; Garreau, Guillaume; Georgiou, Julius

    2016-01-01

    Sand-scorpions and many other arachnids perceive their environment by using their feet to sense ground waves. They are able to determine amplitudes the size of an atom and locate the acoustic stimuli with an accuracy of within 13° based on their neuronal anatomy. We present here a prototype sound source localization system, inspired from this impressive performance. The system presented utilizes custom-built hardware with eight MEMS microphones, one for each foot, to acquire the acoustic scene, and a spiking neural model to localize the sound source. The current implementation shows smaller localization error than those observed in nature.

  1. Sound Source Localization Through 8 MEMS Microphones Array Using a Sand-Scorpion-Inspired Spiking Neural Network

    Directory of Open Access Journals (Sweden)

    Christoph Beck

    2016-10-01

    Full Text Available Sand-scorpions and many other arachnids perceive their environment by using their feet to sense ground waves. They are able to determine amplitudes the size of an atom and locate the acoustic stimuli with an accuracy of within 13° based on their neuronal anatomy. We present here a prototype sound source localization system, inspired from this impressive performance. The system presented utilizes custom-built hardware with eight MEMS microphones, one for each foot, to acquire the acoustic scene, and a spiking neural model to localize the sound source. The current implementation shows smaller localization error than those observed in nature.

  2. Spatial Control of Condensation using Chemical Micropatterns

    Science.gov (United States)

    Murphy, Kevin; Hansen, Ryan; Nath, Saurabh; Retterer, Scott; Collier, Patrick; Boreyko, Jonathan; Nature-Inspired Fluids; Interfaces Team; CenterNanophase Materials Sciences Team

    2015-11-01

    Surfaces exhibiting wettability patterns can spatially control the nucleation of condensation to enable enhanced fog harvesting and phase-change heat transfer. To date, studies of patterned condensation have utilized a combination of chemical and topographical features, making it difficult to isolate the effects of intrinsic wettability versus surface roughness on spatially controlling the condensate. Here, we fabricate chemical micropatterns consisting of hydrophilic silicon oxide and a smooth hydrophobic silane monolayer to isolate the effects of changes in intrinsic wettability on the spatial control of condensation. Complete spatial control, defined as every nucleation and growth event occurring exclusively on the hydrophilic features, was observed even for supercooled droplets at high water vapor supersaturation. However, this complete spatial control was found to break down beyond a critical spacing that depended upon the extent of supersaturation. The average diameter of condensate was found to be smaller for the chemically micropatterned surfaces compared to a uniformly hydrophobic surface. Control of inter-droplet spacing between supercooled condensate through chemical patterning can be employed to minimize the growth of inter-droplet frost on cold surfaces.

  3. Primes, Geometry and Condensed Matter

    Directory of Open Access Journals (Sweden)

    Al Rabeh R. H.

    2009-07-01

    Full Text Available Fascination with primes dates back to the Greeks and before. Primes are named by some “the elementary particles of arithmetic” as every nonprime integer is made of a unique set of primes. In this article we point to new connections between primes, geometry and physics which show that primes could be called “the elementary particles of physics” too. This study considers the problem of closely packing similar circles / spheres in 2D / 3D space. This is in effect a discretization process of space and the allowable num- ber in a pack is found to lead to some unexpected cases of prime configurations which is independent of the size of the constituents. We next suggest that a non-prime can be considered geometrically as a symmetric collection that is separable (factorable into similar parts- six is two threes or three twos for example. A collection that has no such symmetry is a prime. As a result, a physical prime aggregate is more difficult to split symmetrically resulting in an inherent stability. This “number / physical” stability idea applies to bigger collections made from smaller (prime units leading to larger sta- ble prime structures in a limitless scaling up process. The distribution of primes among numbers can be understood better using the packing ideas described here and we further suggest that differing numbers (and values of distinct prime factors making a nonprime collection is an important factor in determining the probability and method of possible and subsequent disintegration. Disintegration is bound by energy conservation and is closely related to symmetry by Noether theorems. Thinking of condensed matter as the packing of identical elements, we examine plots of the masses of chemical elements of the periodic table, and also those of the elementary particles of physics, and show that prime packing rules seem to play a role in the make up of matter. The plots show con- vincingly that the growth of prime numbers and that

  4. Primes, Geometry and Condensed Matter

    Directory of Open Access Journals (Sweden)

    Al Rabeh R. H.

    2009-07-01

    Full Text Available Fascination with primes dates back to the Greeks and before. Primes are named by some "the elementary particles of arithmetic" as every nonprime integer is made of a unique set of primes. In this article we point to new connections between primes, geometry and physics which show that primes could be called "the elementary particles of physics" too. This study considers the problem of closely packing similar circles/spheres in 2D/3D space. This is in effect a discretization process of space and the allowable number in a pack is found to lead to some unexpected cases of prime configurations which is independent of the size of the constituents. We next suggest that a non-prime can be considered geometrically as a symmetric collection that is separable (factorable into similar parts- six is two threes or three twos for example. A collection that has no such symmetry is a prime. As a result, a physical prime aggregate is more difficult to split symmetrically resulting in an inherent stability. This "number/physical" stability idea applies to bigger collections made from smaller (prime units leading to larger stable prime structures in a limitless scaling up process. The distribution of primes among numbers can be understood better using the packing ideas described here and we further suggest that differing numbers (and values of distinct prime factors making a nonprime collection is an important factor in determining the probability and method of possible and subsequent disintegration. Disintegration is bound by energy conservation and is closely related to symmetry by Noether theorems. Thinking of condensed matter as the packing of identical elements, we examine plots of the masses of chemical elements of the periodic table, and also those of the elementary particles of physics, and show that prime packing rules seem to play a role in the make up of matter. The plots show convincingly that the growth of prime numbers and that of the masses of

  5. Mitotic chromosome condensation in vertebrates

    Energy Technology Data Exchange (ETDEWEB)

    Vagnarelli, Paola, E-mail: P.Vagnarelli@ed.ac.uk

    2012-07-15

    Work from several laboratories over the past 10-15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292-301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories-a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307-316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119-1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579-589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different classes

  6. Mitotic chromosome condensation in vertebrates

    International Nuclear Information System (INIS)

    Vagnarelli, Paola

    2012-01-01

    Work from several laboratories over the past 10–15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292–301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories—a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307–316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119–1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579–589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different

  7. Implementation of non-condensable gases condensation suppression model into the WCOBRA/TRAC-TF2 LOCA safety evaluation code

    International Nuclear Information System (INIS)

    Liao, J.; Cao, L.; Ohkawa, K.; Frepoli, C.

    2012-01-01

    The non-condensable gases condensation suppression model is important for a realistic LOCA safety analysis code. A condensation suppression model for direct contact condensation was previously developed by Westinghouse using first principles. The model is believed to be an accurate description of the direct contact condensation process in the presence of non-condensable gases. The Westinghouse condensation suppression model is further revised by applying a more physical model. The revised condensation suppression model is thus implemented into the WCOBRA/TRAC-TF2 LOCA safety evaluation code for both 3-D module (COBRA-TF) and 1-D module (TRAC-PF1). Parametric study using the revised Westinghouse condensation suppression model is conducted. Additionally, the performance of non-condensable gases condensation suppression model is examined in the ACHILLES (ISP-25) separate effects test and LOFT L2-5 (ISP-13) integral effects test. (authors)

  8. Cold Vacuum Drying facility condensate collection system design description

    International Nuclear Information System (INIS)

    PITKOFF, C.C.

    1999-01-01

    This document describes the Cold Vacuum Drying Facility (CVDF) condensate collection system (CCS). The function of the CCS is to collect cooling coil condensate from air-handling units in the CVDF and to isolate the condensate in collection tanks until the condensate is determined to be acceptable to drain to the effluent drain collection basin

  9. Improved condenser design and condenser-fan operation for air-cooled chillers

    International Nuclear Information System (INIS)

    Yu, F.W.; Chan, K.T.

    2006-01-01

    Air-cooled chillers traditionally operate under head pressure control via staging constant-speed condenser fans. This causes a significant drop in their coefficient of performance (COP) at part load or low outdoor temperatures. This paper describes how the COP of these chillers can be improved by a new condenser design, using evaporative pre-coolers and variable-speed fans. A thermodynamic model for an air-cooled screw-chiller was developed, within which the condenser component considers empirical equations showing the effectiveness of an evaporative pre-cooler in lowering the outdoor temperature in the heat-rejection process. The condenser component also contains an algorithm to determine the number and speed of the condenser fans staged at any given set point of condensing temperature. It is found that the chiller's COP can be maximized by adjusting the set point based on any given chiller load and wet-bulb temperature of the outdoor air. A 5.6-113.4% increase in chiller COP can be achieved from the new condenser design and condenser fan operation. This provides important insights into how to develop more energy-efficient air-cooled chillers

  10. GENOTOXICITY OF TEN CIGARETTE SMOKE CONDENSATES IN FOUR TEST SYSTEMS: COMPARISONS BETWEEN ASSAYS AND CONDENSATES

    Science.gov (United States)

    What is the study? This the first assessment of a set of cigarette smoke condensates from a range of cigarette types in a variety (4) of short-term genotoxicity assays. Why was it done? No such comparative study of cigarette smoke condensates has been reported. H...

  11. Steam condensation modelling in aerosol codes

    International Nuclear Information System (INIS)

    Dunbar, I.H.

    1986-01-01

    The principal subject of this study is the modelling of the condensation of steam into and evaporation of water from aerosol particles. These processes introduce a new type of term into the equation for the development of the aerosol particle size distribution. This new term faces the code developer with three major problems: the physical modelling of the condensation/evaporation process, the discretisation of the new term and the separate accounting for the masses of the water and of the other components. This study has considered four codes which model the condensation of steam into and its evaporation from aerosol particles: AEROSYM-M (UK), AEROSOLS/B1 (France), NAUA (Federal Republic of Germany) and CONTAIN (USA). The modelling in the codes has been addressed under three headings. These are the physical modelling of condensation, the mathematics of the discretisation of the equations, and the methods for modelling the separate behaviour of different chemical components of the aerosol. The codes are least advanced in area of solute effect modelling. At present only AEROSOLS/B1 includes the effect. The effect is greater for more concentrated solutions. Codes without the effect will be more in error (underestimating the total airborne mass) the less condensation they predict. Data are needed on the water vapour pressure above concentrated solutions of the substances of interest (especially CsOH and CsI) if the extent to which aerosols retain water under superheated conditions is to be modelled. 15 refs

  12. Increasing the efficiency of the condensing boiler

    Science.gov (United States)

    Zaytsev, ON; Lapina, EA

    2017-11-01

    Analysis of existing designs of boilers with low power consumption showed that the low efficiency of the latter is due to the fact that they work in most cases when the heating period in the power range is significantly less than the nominal power. At the same time, condensing boilers do not work in the most optimal mode (in condensing mode) in the central part of Russia, a significant part of their total operating time during the heating season. This is due to existing methods of equipment selection and joint operation with heating systems with quantitative control of the coolant. It was also revealed that for the efficient operation of the heating system, it is necessary to reduce the inertia of the heat generating equipment. Theoretical patterns of thermal processes in the furnace during combustion gas at different radiating surfaces location schemes considering the influence of the very furnace configuration, characterized in that to reduce the work condensing boiler in conventional gas boiler operation is necessary to maintain a higher temperature in the furnace (in the part where spiral heat exchangers are disposed), which is possible when redistributing heat flow - increase the proportion of radiant heat from the secondary burner emitter allow Perey For the operation of the condensing boiler in the design (condensation) mode practically the entire heating period.

  13. Laser Isotope Separation Employing Condensation Repression

    Energy Technology Data Exchange (ETDEWEB)

    Eerkens, Jeff W.; Miller, William H.

    2004-09-15

    Molecular laser isotope separation (MLIS) techniques using condensation repression (CR) harvesting are reviewed and compared with atomic vapor laser isotope separation (AVLIS), gaseous diffusion (DIF), ultracentrifuges (UCF), and electromagnetic separations (EMS). Two different CR-MLIS or CRISLA (Condensation Repression Isotope Separation by Laser Activation) approaches have been under investigation at the University of Missouri (MU), one involving supersonic super-cooled free jets and dimer formation, and the other subsonic cold-wall condensation. Both employ mixtures of an isotopomer (e.g. {sup i}QF{sub 6}) and a carrier gas, operated at low temperatures and pressures. Present theories of VT relaxation, dimerization, and condensation are found to be unsatisfactory to explain/predict experimental CRISLA results. They were replaced by fundamentally new models that allow ab-initio calculation of isotope enrichments and predictions of condensation parameters for laser-excited and non-excited vapors which are in good agreement with experiment. Because of supersonic speeds, throughputs for free-jet CRISLA are a thousand times higher than cold-wall CRISLA schemes, and thus preferred for large-quantity Uranium enrichments. For small-quantity separations of (radioactive) medical isotopes, the simpler coldwall CRISLA method may be adequate.

  14. The NSF Condensed Matter Physics Program

    Science.gov (United States)

    Sokol, Paul

    The Condensed Matter Physics (CMP) program in the NSF Division of Materials Research (DMR) supports experimental, as well as combined experiment and theory projects investigating the fundamental physics behind phenomena exhibited by condensed matter systems. CMP is the largest Individual Investigator Award program in DMR and supports a broad portfolio of research spanning both hard and soft condensed matter. Representative research areas include: 1) phenomena at the nano- to macro-scale including: transport, magnetic, and optical phenomena; classical and quantum phase transitions; localization; electronic, magnetic, and lattice structure or excitations; superconductivity; topological insulators; and nonlinear dynamics. 2) low-temperature physics: quantum fluids and solids; 1D & 2D electron systems. 3) soft condensed matter: partially ordered fluids, granular and colloid physics, liquid crystals, and 4) understanding the fundamental physics of new states of matter as well as the physical behavior of condensed matter under extreme conditions e.g., low temperatures, high pressures, and high magnetic fields. In this talk I will review the current CMP portfolio and discuss future funding trends for the program. I will also describe recent activities in the program aimed at addressing the challenges facing current and future principal investigators.

  15. Condensate and feedwater systems, pumps, and water chemistry. Volume seven

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Subject matter includes condensate and feedwater systems (general features of condensate and feedwater systems, condenser hotwell level control, condensate flow, feedwater flow), pumps (principles of fluid flow, types of pumps, centrifugal pumps, positive displacement pumps, jet pumps, pump operating characteristics) and water chemistry (water chemistry fundamentals, corrosion, scaling, radiochemistry, water chemistry control processes, water pretreatment, PWR water chemistry, BWR water chemistry, condenser circulating water chemistry

  16. Heavy-quark expansion, factorization and 8-dimensional gluon condensates

    International Nuclear Information System (INIS)

    Bagan, E.; Latorre, J.I.; Pascual, P.; Tarrach, R.

    1985-01-01

    We analyze the phenomenon of heavy-quark condensation within the framework of the QCD sum rule approach, and apply the consequences of this analysis to the heavy-quark expansion. This technique allows one to relate 6-dimensional quark condensates with quartic 8-dimensional gluon condensates. Factorization of the quark condensates together with the specific feature of 3 condensates, which we believe to be well-founded. (orig.)

  17. Preoperational test report, recirculation condenser cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, F.T.

    1997-11-04

    This represents a preoperational test report for Recirculation Condenser Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The four system provide condenser cooling water for vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102. Each system consists of a valved piping loop, a pair of redundant recirculation pumps, a closed-loop evaporative cooling tower, and supporting instrumentation; equipment is located outside the farm on concrete slabs. Piping is routed to the each ventilation condenser inside the farm via below-grade concrete trenches. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  18. Preoperational test report, recirculation condenser cooling systems

    International Nuclear Information System (INIS)

    Clifton, F.T.

    1997-01-01

    This represents a preoperational test report for Recirculation Condenser Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The four system provide condenser cooling water for vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102. Each system consists of a valved piping loop, a pair of redundant recirculation pumps, a closed-loop evaporative cooling tower, and supporting instrumentation; equipment is located outside the farm on concrete slabs. Piping is routed to the each ventilation condenser inside the farm via below-grade concrete trenches. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System

  19. Bose-Einstein condensation of atomic gases

    International Nuclear Information System (INIS)

    Anglin, J. R.; Ketterle, W.

    2003-01-01

    The early experiments on Bose-Einstein condensation in dilute atomic gases accomplished three longstanding goals. First, cooling of neutral atoms into their motional state, thus subjecting them to ultimate control, limited only by Heisenberg uncertainty relation. Second, creation of a coherent sample of atoms, in which all occupy the same quantum states, and the realization of atom lasers - devices that output coherent matter waves. And third, creation of gaseous quantum fluid, with properties that are different from the quantum liquids helium-3 and helium-4. The field of Bose-Einstein condensation of atomic gases has continued to progress rapidly, driven by the combination of new experimental techniques and theoretical advances. The family of quantum degenerate gases has grown, and now includes metastable and fermionic atoms. condensates have become an ultralow-temperature laboratory for atom optics, collisional physics and many-body physics, encompassing phonons, superfluidity, quantized vortices, Josephson junctions and quantum phase transitions. (author)

  20. From particle condensation to polymer aggregation

    Science.gov (United States)

    Janke, Wolfhard; Zierenberg, Johannes

    2018-01-01

    We draw an analogy between droplet formation in dilute particle and polymer systems. Our arguments are based on finite-size scaling results from studies of a two-dimensional lattice gas to three-dimensional bead-spring polymers. To set the results in perspective, we compare with in part rigorous theoretical scaling laws for canonical condensation in a supersaturated gas at fixed temperature, and derive corresponding scaling predictions for an undercooled gas at fixed density. The latter allows one to efficiently employ parallel multicanonical simulations and to reach previously not accessible scaling regimes. While the asymptotic scaling can not be observed for the comparably small polymer system sizes, they demonstrate an intermediate scaling regime also observable for particle condensation. Altogether, our extensive results from computer simulations provide clear evidence for the close analogy between particle condensation and polymer aggregation in dilute systems.

  1. Dropwise condensation on inclined textured surfaces

    CERN Document Server

    Khandekar, Sameer

    2014-01-01

    Dropwise Condensation on Textured Surfaces presents a holistic framework for understanding dropwise condensation through mathematical modeling and meaningful experiments. The book presents a review of the subject required to build up models as well as to design experiments. Emphasis is placed on the effect of physical and chemical texturing and their effect on the bulk transport phenomena. Application of the model to metal vapor condensation is of special interest. The unique behavior of liquid metals, with their low Prandtl number and high surface tension, is also discussed. The model predicts instantaneous drop size distribution for a given level of substrate subcooling and derives local as well as spatio-temporally averaged heat transfer rates and wall shear stress.

  2. Condensate of massive graviton and dark matter

    Science.gov (United States)

    Aoki, Katsuki; Maeda, Kei-ichi

    2018-02-01

    We study coherently oscillating massive gravitons in the ghost-free bigravity theory. This coherent field can be interpreted as a condensate of the massive gravitons. We first define the effective energy-momentum tensor of the coherent massive gravitons in a curved spacetime. We then study the background dynamics of the Universe and the cosmic structure formation including the effects of the coherent massive gravitons. We find that the condensate of the massive graviton behaves as a dark matter component of the Universe. From the geometrical point of view the condensate is regarded as a spacetime anisotropy. Hence, in our scenario, dark matter is originated from the tiny deformation of the spacetime. We also discuss a production of the spacetime anisotropy and find that the extragalactic magnetic field of a primordial origin can yield a sufficient amount for dark matter.

  3. Temporal dynamics of Bose-condensed gases

    Energy Technology Data Exchange (ETDEWEB)

    Trujillo Martinez, Mauricio

    2014-03-19

    We perform a detailed quantum dynamical study of non-equilibrium trapped, interacting Bose-condensed gases. We investigate Josephson oscillations between interacting Bose-Einstein condensates confined in a finite size double-well trap and the non-trivial time evolution of a coherent state placed at the center of a two dimensional optical lattice. For the Josephson oscillations three time scales appear. We find that Josephson junction can sustain multiple undamped oscillations up to a characteristic time scale τ{sub c} without exciting atoms out of the condensates. Beyond the characteristic time scale τ{sub c} the dynamics of the junction are governed by fast, non-condensed particles assisted Josephson tunnelling as well as the collisions between non-condensed particles. In the non-condensed particles dominated regime we observe strong damping of the oscillations due to inelastic collisions, equilibrating the system leading to an effective loss of details of the initial conditions. In addition, we predict that an initially self-trapped BEC state will be destroyed by these fast dynamics. The time evolution of a coherent state released at the center of a two dimensional optical lattice shows a ballistic expansion with a decreasing expansion velocity for increasing two-body interactions strength and particle number. Additionally, we predict that if the two-body interactions strength exceeds a certain value, a forerunner splits up from the expanding coherent state. We also observe that this system, which is prepared far from equilibrium, can evolve to a quasistationary non-equilibrium state.

  4. Composition of gases vented from a condenser

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, R.N.

    1980-08-01

    Designers of systems that involve condensers often need to predict the amount of process vapor that accompanies the noncondensable gases that are vented from the condensers. An approximation is given that appears to provide, in many cases, reasonably accurate values for the mole ratio of process vapor to noncondensable gases in the vented mixture. The approximation is particularly applicable to flash and direct-contact power systems for geothermal brines and ocean thermal energy conversion (OTEC). More regorous relationships are available for exceptional cases.

  5. Bose-condensation through resonance decay

    International Nuclear Information System (INIS)

    Ornik, U.; Pluemer, M.; Strottman, D.

    1993-04-01

    We show that a system described by an equation of state which contains a high number of degrees of freedom (resonances) can create a considerable amount of superfluid (condensed) pions through the decay of short-lived resonances, if baryon number and entropy are large and the dense matter decouples from chemical equilibrium earlier than from thermal equilibrium. The system cools down faster in the presence of a condensate, an effect that may partially compensate the enhancement of the lifetime expected in the case of quark-gluon-plasma formation. (orig.). 3 figs

  6. Tunneling problems between Bose-Einstein condensates

    International Nuclear Information System (INIS)

    Watabe, Shohei; Kato, Yusuke

    2009-01-01

    We investigate transmission and reflection of Bose-Einstein condensate excitations in the low-energy limit across a potential barrier separating two condensates with different densities. Bogoliubov excitation in the low-energy limit has an incident angle where perfect transmission occurs. This condition corresponds to the Brewster's law for the electromagnetic wave. There also exists the total internal reflection of the Bogoliubov excitation in the low-energy limit. In the case of the normal incidence, our result in the low-energy limit is consistent with a result for weakly interacting one-dimensional Bose gases treated as Tomonaga-Luttinger liquids.

  7. Tunneling problems between Bose-Einstein condensates

    Energy Technology Data Exchange (ETDEWEB)

    Watabe, Shohei [Department of Physics, University of Tokyo, Tokyo, Tokyo, 113-0033 (Japan); Kato, Yusuke [Department of Basic Science, University of Tokyo, Tokyo, 153-8902 (Japan)], E-mail: watabe@vortex.c.u-tokyo.ac.jp

    2009-02-01

    We investigate transmission and reflection of Bose-Einstein condensate excitations in the low-energy limit across a potential barrier separating two condensates with different densities. Bogoliubov excitation in the low-energy limit has an incident angle where perfect transmission occurs. This condition corresponds to the Brewster's law for the electromagnetic wave. There also exists the total internal reflection of the Bogoliubov excitation in the low-energy limit. In the case of the normal incidence, our result in the low-energy limit is consistent with a result for weakly interacting one-dimensional Bose gases treated as Tomonaga-Luttinger liquids.

  8. Turbulent meson condensation in quark deconfinement

    Directory of Open Access Journals (Sweden)

    Koji Hashimoto

    2015-06-01

    Full Text Available In a QCD-like strongly coupled gauge theory at large Nc, using the AdS/CFT correspondence, we find that heavy quark deconfinement is accompanied by a coherent condensation of higher meson resonances. This is revealed in non-equilibrium deconfinement transitions triggered by static, as well as quenched electric fields even below the Schwinger limit. There, we observe a “turbulent” energy flow to higher meson modes, which finally results in the quark deconfinement. Our observation is consistent with seeing deconfinement as a condensation of long QCD strings.

  9. Colored condensates deep inside neutron stars

    Directory of Open Access Journals (Sweden)

    Blaschke David

    2014-01-01

    Full Text Available It is demonstrated how in the absence of solutions for QCD under conditions deep inside compact stars an equation of state can be obtained within a model that is built on the basic symmetries of the QCD Lagrangian, in particular chiral symmetry and color symmetry. While in the vacuum the chiral symmetry is spontaneously broken, it gets restored at high densities. Color symmetry, however, gets broken simultaneously by the formation of colorful diquark condensates. It is shown that a strong diquark condensate in cold dense quark matter is essential for supporting the possibility that such states could exist in the recently observed pulsars with masses of 2 Mʘ.

  10. Analysis of Acoustic Feedback/Echo Cancellation in Multiple-Microphone and Single-Loudspeaker Systems Using a Power Transfer Function Method

    DEFF Research Database (Denmark)

    Guo, Meng; Bo Elmedyb, Thomas; Jensen, Søren Holdt

    2011-01-01

    In this work, we analyze a general multiple-microphone and single-loudspeaker audio processing system, where a multichannel adaptive system is used to cancel the effect of acoustic feedback/echo, and a beamformer processes the feedback/echo canceled signals. We introduce and derive an accurate...

  11. Extending the frequency range of free-field reciprocity calibration of measurement microphones to frequencies up to 150 kHz

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Torras Rosell, Antoni; Jacobsen, Finn

    2013-01-01

    Measurement microphones are typically calibrated in a free field at frequencies up to 50 kHz. This is a sufficiently high frequency for the most sound measurement applications related with noise assessment. However, other applications such as the measurement of noise emitted by ultrasound cleanin...

  12. A Portable Infrasonic Detection System

    Science.gov (United States)

    Shams, Qamar A.; Burkett, Cecil G.; Zuckerwar, Allan J.; Lawrenson, Christopher C.; Masterman, Michael

    2008-01-01

    During last couple of years, NASA Langley has designed and developed a portable infrasonic detection system which can be used to make useful infrasound measurements at a location where it was not possible previously. The system comprises an electret condenser microphone, having a 3-inch membrane diameter, and a small, compact windscreen. Electret-based technology offers the lowest possible background noise, because Johnson noise generated in the supporting electronics (preamplifier) is minimized. The microphone features a high membrane compliance with a large backchamber volume, a prepolarized backplane and a high impedance preamplifier located inside the backchamber. The windscreen, based on the high transmission coefficient of infrasound through matter, is made of a material having a low acoustic impedance and sufficiently thick wall to insure structural stability. Close-cell polyurethane foam has been found to serve the purpose well. In the proposed test, test parameters will be sensitivity, background noise, signal fidelity (harmonic distortion), and temporal stability. The design and results of the compact system, based upon laboratory and field experiments, will be presented.

  13. Pollen grains are efficient cloud condensation nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pope, F D, E-mail: fdp21@cam.ac.uk [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2010-10-15

    This letter presents a laboratory study investigating the ability of pollen grains to act as cloud condensation nuclei. The hygroscopicity of pollen is measured under subsaturated relative humidities using an electrodynamic balance. It is found, along with other results, that pollen exhibits bulk uptake of water under subsaturated conditions. Through the use of an environmental scanning electron microscope it was observed that the surface of pollen is wettable at high subsaturated humidities. The hygroscopic response of the pollen to subsaturated relative humidities is parametrized using {kappa}-Koehler theory and values of the parameter {kappa} for pollen are between 0.05 and 0.1. It is found that while pollen grains are only moderately hygroscopic, they can activate at critical supersaturations of 0.001% and lower, and thus pollen grains will readily act as cloud condensation nuclei. While the number density of pollen grains is too low for them to represent a significant global source of cloud condensation nuclei, the large sizes of pollen grains suggest that they will be an important source of giant cloud condensation nuclei. Low temperature work using the environmental scanning electron microscope indicated that pollen grains do not act as deposition ice nuclei at temperatures warmer than - 15 deg. C.

  14. The quark condensate in a nuclear environment

    Energy Technology Data Exchange (ETDEWEB)

    Weise, W. [Regensburg Univ. (Germany). Inst. of Theoretical Physics

    1995-12-31

    A summary and survey on the change of the chiral condensate in dense (and hot) matter is presented. Implications for nuclear physics and relativistic heavy ion collisions are discussed, such as the strong Dirac scalar mean field that results from the density dependence of , and possible consequences for decreasing hadron masses in matter. (author). 22 refs., 4 figs.

  15. Condensation energy of the superconducting bilayer cuprates

    Indian Academy of Sciences (India)

    May & June 2002 physics pp. 861–866. Condensation energy of the superconducting bilayer cuprates. GOVIND1, AJAY2 and S K JOSHI1,3,∗. 1Theory Group, National Physical Laboratory, Dr. K.S. ... 2Department of Physics, G.B. Pant University of Agriculture and Technology, ..... [1] B Batlogg, Physics Today 44, 45 (1991).

  16. Cloud condensation nuclei from biomass burning

    International Nuclear Information System (INIS)

    Rogers, C.F.; Hudson, J.G.; Zielinska, B.; Tanner, R.L.; Hallett, J.; Watson, J.G.

    1991-01-01

    In this work, the authors have analyzed biomass and crude oil smoke samples for ionic and organic species. The cloud condensation nuclei activities of the smoke particles are discussed in terms of the measured chemical compositions of the smoke samples. The implications of biomass burning to global climatic change are discussed

  17. Free convective condensation in a vertical enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Fox, R.J.; Peterson, P.F. [Univ. of California, Berkeley, CA (United States); Corradini, M.L.; Pernsteiner, A.P. [Univ. of Wisconsin, Madison, WI (United States)

    1995-09-01

    Free convective condensation in a vertical enclosure was studied numerically and the results were compared with experiments. In both the numerical and experimental investigations, mist formation was observed to occur near the cooling wall, with significant droplet concentrations in the bulk. Large recirculation cells near the end of the condensing section were generated as the heavy noncondensing gas collecting near the cooling wall was accelerated downward. Near the top of the enclosure the recirculation cells became weaker and smaller than those below, ultimately disappearing near the top of the condenser. In the experiment the mist density was seen to be highest near the wall and at the bottom of the condensing section, whereas the numerical model predicted a much more uniform distribution. The model used to describe the formation of mist was based on a Modified Critical Saturation Model (MCSM), which allows mist to be generated once the vapor pressure exceeds a critical value. Equilibrium, nonequilibrium, and MCSM calculations were preformed, showing the experimental results to lie somewhere in between the equilibrium and nonequilibrium predictions of the numerical model. A single adjustable constant (indicating the degree to which equilibrium is achieved) is used in the model in order to match the experimental results.

  18. Mathematical modelling of dropwise condensation on textured ...

    Indian Academy of Sciences (India)

    Abstract. Vapor-to-liquid phase change in the form of discrete drops on or under- neath a substrate is called dropwise condensation. The process is hierarchical in the sense that it occurs over a wide range of length and timescales. As the associated heat transfer coefficient is much higher than the film and mixed mode of ...

  19. Fractional condensation of biomass pyrolysis vapors

    NARCIS (Netherlands)

    Westerhof, Roel Johannes Maria; Brilman, Derk Willem Frederik; Garcia Perez, M.; Wang, Zhouhong; Oudenhoven, Stijn; van Swaaij, Willibrordus Petrus Maria; Kersten, Sascha R.A.

    2011-01-01

    In this paper, we have investigated the possibilities to steer the composition and, thus, the quality of pyrolysis liquids by the reactor temperature and the pyrolysis vapor condenser temperature. Pine wood was pyrolyzed in a 1 kg/h fluidized-bed pyrolysis reactor operated at 330 or 480 °C. The

  20. Production of clean gasoline from the condensate

    Directory of Open Access Journals (Sweden)

    Noureddin Bentahar

    2013-12-01

    Full Text Available The locally available Algerian bentonite is explored to prepare catalysts for the isomerization of the light fractions of Algerian condensate to produce high quality gasoline of high octane number. Satisfying results are obtained which render these catalysts applicable for a large scale production.

  1. Scalar Condensation of Holographic Superconductors using ...

    Indian Academy of Sciences (India)

    2016-01-27

    Landau action with the -quartic term |Ψ|4. Our results show that -term plays a role in the scalar condensation. It is found that the system displays two kinds of critical temperatures. One is independent of . But the other increases ...

  2. Thermal condensation mode in a dusty plasma

    Indian Academy of Sciences (India)

    Abstract. In the present work, the radiative condensation instability is investigated in the presence of dust charge fluctuations. We find that the charge variability of the grain reduces the growth rate of radiative mode only for fluctuation wavelength smaller or of the order of the Debye length and this reduction is not very large.

  3. optimal evaporating and condensing temperatures of organic

    African Journals Online (AJOL)

    user

    36, No. 1, January, 2017 111. The heat input to the ORCplants is dependent on a wide range of heat sources ‒ namely waste heat from the condenser of a conventional or a nuclear power plant, waste heat from industrial processes, solar radiation, and geothermal energy. The solar power plant has a well-.

  4. Factorised steady states and condensation transitions in ...

    Indian Academy of Sciences (India)

    I will then consider a more general class of mass trans- port models, encompassing continuous mass variables and discrete time updating, and present a necessary and sufficient condition for the steady state to factorise. The prop- erty of factorisation again allows an analysis of the condensation transitions which may occur.

  5. CONVECTION IN CONDENSIBLE-RICH ATMOSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Ding, F. [Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637 (United States); Pierrehumbert, R. T., E-mail: fding@uchicago.edu [Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom)

    2016-05-01

    Condensible substances are nearly ubiquitous in planetary atmospheres. For the most familiar case—water vapor in Earth’s present climate—the condensible gas is dilute, in the sense that its concentration is everywhere small relative to the noncondensible background gases. A wide variety of important planetary climate problems involve nondilute condensible substances. These include planets near or undergoing a water vapor runaway and planets near the outer edge of the conventional habitable zone, for which CO{sub 2} is the condensible. Standard representations of convection in climate models rely on several approximations appropriate only to the dilute limit, while nondilute convection differs in fundamental ways from dilute convection. In this paper, a simple parameterization of convection valid in the nondilute as well as dilute limits is derived and used to discuss the basic character of nondilute convection. The energy conservation properties of the scheme are discussed in detail and are verified in radiative-convective simulations. As a further illustration of the behavior of the scheme, results for a runaway greenhouse atmosphere for both steady instellation and seasonally varying instellation corresponding to a highly eccentric orbit are presented. The latter case illustrates that the high thermal inertia associated with latent heat in nondilute atmospheres can damp out the effects of even extreme seasonal forcing.

  6. Tunneling of trapped-atom Bose condensates

    Indian Academy of Sciences (India)

    Abstract. We obtain the dynamics in number and phase difference, for Bose condensates that tun- nel between two wells of a double-well atomic trap, using the (nonlinear) Gross–Pitaevskii equation. The dynamical equations are of the canonical form for the two conjugate variables, and the Hamil- tonian corresponds to that ...

  7. Condensate formation in a Bose gas

    NARCIS (Netherlands)

    Stoof, H.T.C.

    1995-01-01

    Using magnetically trapped atomic hydrogen as an example, we investigate the prospects of achieving Bose-Einstein condensation in a dilute Bose gas. We show that, if gas is quenched sufficiently far into the critical region of the phase transition, the typical time scale for the nucleation of the

  8. A transport-based condensed history algorithm

    International Nuclear Information System (INIS)

    Tolar, D. R. Jr.

    1999-01-01

    Condensed history algorithms are approximate electron transport Monte Carlo methods in which the cumulative effects of multiple collisions are modeled in a single step of (user-specified) path length s 0 . This path length is the distance each Monte Carlo electron travels between collisions. Current condensed history techniques utilize a splitting routine over the range 0 le s le s 0 . For example, the PEnELOPE method splits each step into two substeps; one with length ξs 0 and one with length (1 minusξ)s 0 , where ξ is a random number from 0 0 is fixed (not sampled from an exponential distribution), conventional condensed history schemes are not transport processes. Here the authors describe a new condensed history algorithm that is a transport process. The method simulates a transport equation that approximates the exact Boltzmann equation. The new transport equation has a larger mean free path than, and preserves two angular moments of, the Boltzmann equation. Thus, the new process is solved more efficiently by Monte Carlo, and it conserves both particles and scattering power

  9. ISOSPIN BREAKING AND THE CHIRAL CONDENSATE.

    Energy Technology Data Exchange (ETDEWEB)

    CREUTZ, M.

    2005-07-25

    With two degenerate quarks, the chiral condensate exhibits a jump as the quark masses pass through zero. I discuss how this single transition splits into two Ising like transitions when the quarks are made non-degenerate. The order parameter is the expectation of the neutral pion field. The transitions represent long distance coherent phenomena occurring without the Dirac operator having vanishingly small eigenvalues.

  10. Orientifold Planar Equivalence: The Chiral Condensate

    DEFF Research Database (Denmark)

    Armoni, Adi; Lucini, Biagio; Patella, Agostino

    2008-01-01

    ) representation and $N_f$ flavours of Majorana fermions in the adjoint representation have the same large $N$ value for any value of the mass of the (degenerate) fermions. Assuming the invariance of the theory under charge conjugation, we prove this statement on the lattice for staggered quenched condensates...

  11. Connections between quantum chromodynamics and condensed ...

    Indian Academy of Sciences (India)

    Recently some of the analyses that originated in condensed matter physics have found applications in QCD. Using examples we discuss some of the connections between the two fields and show how progress can be made by exploiting this connection. Some of the challenges that remain in the two fields are quite similar.

  12. Tachyon condensation and black hole entropy.

    Science.gov (United States)

    Dabholkar, Atish

    2002-03-04

    String propagation on a cone with deficit angle 2pi(1-1 / N) is considered for the purpose of computing the entropy of a large mass black hole. The entropy computed using the recent results on condensation of twisted-sector tachyons in this theory is found to be in precise agreement with the Bekenstein-Hawking entropy.

  13. Tunneling of trapped-atom Bose condensates

    Indian Academy of Sciences (India)

    We obtain the dynamics in number and phase difference, for Bose condensates that tunnel between two wells of a double-well atomic trap, using the (nonlinear) Gross–Pitaevskii equation. The dynamical equations are of the canonical form for the two conjugate variables, and the Hamiltonian corresponds to that of a ...

  14. Condensation in a two-phase pool

    International Nuclear Information System (INIS)

    Duffey, R.B.; Hughes, E.D.

    1991-01-01

    We consider the case of vapor condensation in a liquid pool, when the heat transfer is controlled by heat losses through the walls. The analysis is based on drift flux theory for phase separation in the pool, and determines the two-phase mixture height for the pool. To our knowledge this is the first analytical treatment of this classic problem that gives an explicit result, previous work having established the result for the evaporative case. From conservation of mass and energy in a one-dimensional steady flow, together with a void relation between the liquid and vapor fluxes, we determine the increase in the mixture level from the base level of the pool. It can be seen that the thermal and hydrodynamic influences are separable. Thus, the thermal influence of the wall heat transfer appears through its effect on the condensing length L*, so that at high condensation rates the pool is all liquid, and at low rates overflows (the level swell or foaming effect). Similarly, the phase separation effect hydrodynamically determines the height via the relative velocity of the mixture to the entering flux. We examine some practical applications of this result to level swell in condensing flows, and also examine some limits in ideal cases

  15. Vast Antimatter Regions and Scalar Condensate Baryogenesis

    OpenAIRE

    Kirilova, D P; Panayotova, M P; Valchanov, T

    2002-01-01

    The possibility of natural and abundant creation of antimatter in the Universe in a SUSY-baryogenesis model with a scalar field condensate is described. This scenario predicts vast quantities of antimatter, corresponding to galaxy and galaxy cluster scales today, separated from the matter ones by baryonically empty voids. Theoretical and observational constraints on such antimatter regions are discussed.

  16. Activity, purification, and analysis of condensed tannins

    Science.gov (United States)

    As a class of plant polyphenolic compounds contained in some forages (i.e., sanfoin, big trefoil, birdfoot trefoil), condensed tannins (CTs), also referred to as proanthocyanidins (PAs), exhibit a variety of biological effects on ruminants and on the dairy farm nitrogen cycle. Interest in CTs stems ...

  17. Condensed matter studies by nuclear methods

    International Nuclear Information System (INIS)

    Krolas, K.; Tomala, K.

    1988-01-01

    The separate abstract was prepared for 1 of the papers in this volume. The remaining 13 papers dealing with the use but not with advances in the use of nuclear methods in studies of condensed matter, were considered outside the subject scope of INIS. (M.F.W.)

  18. Fundamentals of neutron scattering by condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Scherm, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1996-12-31

    The purpose of this introductory lecture is to give the basic facts about the scattering of neutrons by condensed matter. This lecture is restricted to nuclear scattering, whereas magnetic scattering will be dealt with in an other course. Most of the formalism, however, can also be easily extended to magnetic scattering. (author) 17 figs., 3 tabs., 10 refs.

  19. A simple analytic solution for Tachyon condensation

    Czech Academy of Sciences Publication Activity Database

    Erler, T.; Schnabl, Martin

    -, č. 10 (2009), 066/1-066/35 ISSN 1126-6708 Grant - others:EUROHORC and ESF(XE) EYI/07/E010 Institutional research plan: CEZ:AV0Z10100502 Keywords : string field theory * Tachyon condensation Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 6.019, year: 2009 http://arxiv.org/abs/0906.0979

  20. Spermine Condenses DNA, but Not RNA Duplexes

    Energy Technology Data Exchange (ETDEWEB)

    Katz, Andrea M.; Tolokh, Igor S.; Pabit, Suzette A.; Baker, Nathan; Onufriev, Alexey V.; Pollack, Lois

    2017-01-01

    Interactions between the polyamine spermine and nucleic acids drive important cellular processes. Spermine condenses DNA, and some RNAs such as poly(rA):poly(rU). A large fraction of the spermine present in cells is bound to RNA, but apparently does not condense it. Here, we study the effect of spermine binding to short duplex RNA and DNA and compare our findings with predictions of molecular dynamics simulations. When small numbers of spermine are introduced, RNA with a designed sequence, containing a mixture of 14 GC pairs and 11 AU pairs, resists condensation relative to DNA of an equivalent sequence or to 25 base pair poly(rA):poly(rU) RNA. Comparison of wide-angle x-ray scattering profiles with simulation suggests that spermine is sequestered deep within the major groove of mixed sequence RNA, preventing condensation by limiting opportunities to bridge to other molecules as well as stabilizing the RNA by locking it into a particular conformation. In contrast, for DNA, simulations suggest that spermine binds external to the duplex, offering opportunities for intermolecular interaction. The goal of this study is to explain how RNA can remain soluble, and available for interaction with other molecules in the cell, despite the presence of spermine at concentrations high enough to precipitate DNA.